xnu-7195.60.75.tar.gz

[apple/xnu.git] / osfmk / vm / vm_map.c

/*
 * Copyright (c) 2000-2020 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * @OSF_COPYRIGHT@
 */
/*
 * Mach Operating System
 * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
 * All Rights Reserved.
 *
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */
/*
 */
/*
 *      File:   vm/vm_map.c
 *      Author: Avadis Tevanian, Jr., Michael Wayne Young
 *      Date:   1985
 *
 *      Virtual memory mapping module.
 */

#include <task_swapper.h>
#include <mach_assert.h>

#include <vm/vm_options.h>

#include <libkern/OSAtomic.h>

#include <mach/kern_return.h>
#include <mach/port.h>
#include <mach/vm_attributes.h>
#include <mach/vm_param.h>
#include <mach/vm_behavior.h>
#include <mach/vm_statistics.h>
#include <mach/memory_object.h>
#include <mach/mach_vm.h>
#include <machine/cpu_capabilities.h>
#include <mach/sdt.h>

#include <kern/assert.h>
#include <kern/backtrace.h>
#include <kern/counters.h>
#include <kern/exc_guard.h>
#include <kern/kalloc.h>
#include <kern/zalloc_internal.h>

#include <vm/cpm.h>
#include <vm/vm_compressor.h>
#include <vm/vm_compressor_pager.h>
#include <vm/vm_init.h>
#include <vm/vm_fault.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/pmap.h>
#include <vm/vm_kern.h>
#include <ipc/ipc_port.h>
#include <kern/sched_prim.h>
#include <kern/misc_protos.h>

#include <mach/vm_map_server.h>
#include <mach/mach_host_server.h>
#include <vm/vm_protos.h>
#include <vm/vm_purgeable_internal.h>

#include <vm/vm_protos.h>
#include <vm/vm_shared_region.h>
#include <vm/vm_map_store.h>

#include <san/kasan.h>

#include <sys/codesign.h>
#include <sys/mman.h>

#include <libkern/section_keywords.h>
#if DEVELOPMENT || DEBUG
extern int proc_selfcsflags(void);
int panic_on_unsigned_execute = 0;
#endif /* DEVELOPMENT || DEBUG */

#if MACH_ASSERT
int debug4k_filter = 0;
char debug4k_proc_name[1024] = "";
int debug4k_proc_filter = (int)-1 & ~(1 << __DEBUG4K_FAULT);
int debug4k_panic_on_misaligned_sharing = 0;
const char *debug4k_category_name[] = {
        "error",        /* 0 */
        "life",         /* 1 */
        "load",         /* 2 */
        "fault",        /* 3 */
        "copy",         /* 4 */
        "share",        /* 5 */
        "adjust",       /* 6 */
        "pmap",         /* 7 */
        "mementry",     /* 8 */
        "iokit",        /* 9 */
        "upl",          /* 10 */
        "exc",          /* 11 */
        "vfs"           /* 12 */
};
#endif /* MACH_ASSERT */
int debug4k_no_cow_copyin = 0;


#if __arm64__
extern const int fourk_binary_compatibility_unsafe;
extern const int fourk_binary_compatibility_allow_wx;
#endif /* __arm64__ */
extern int proc_selfpid(void);
extern char *proc_name_address(void *p);

#if VM_MAP_DEBUG_APPLE_PROTECT
int vm_map_debug_apple_protect = 0;
#endif /* VM_MAP_DEBUG_APPLE_PROTECT */
#if VM_MAP_DEBUG_FOURK
int vm_map_debug_fourk = 0;
#endif /* VM_MAP_DEBUG_FOURK */

SECURITY_READ_ONLY_LATE(int) vm_map_executable_immutable = 1;
int vm_map_executable_immutable_verbose = 0;

os_refgrp_decl(static, map_refgrp, "vm_map", NULL);

extern u_int32_t random(void);  /* from <libkern/libkern.h> */
/* Internal prototypes
 */

static void vm_map_simplify_range(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end);   /* forward */

static boolean_t        vm_map_range_check(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end,
        vm_map_entry_t  *entry);

static vm_map_entry_t   _vm_map_entry_create(
        struct vm_map_header    *map_header, boolean_t map_locked);

static void             _vm_map_entry_dispose(
        struct vm_map_header    *map_header,
        vm_map_entry_t          entry);

static void             vm_map_pmap_enter(
        vm_map_t                map,
        vm_map_offset_t         addr,
        vm_map_offset_t         end_addr,
        vm_object_t             object,
        vm_object_offset_t      offset,
        vm_prot_t               protection);

static void             _vm_map_clip_end(
        struct vm_map_header    *map_header,
        vm_map_entry_t          entry,
        vm_map_offset_t         end);

static void             _vm_map_clip_start(
        struct vm_map_header    *map_header,
        vm_map_entry_t          entry,
        vm_map_offset_t         start);

static void             vm_map_entry_delete(
        vm_map_t        map,
        vm_map_entry_t  entry);

static kern_return_t    vm_map_delete(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end,
        int             flags,
        vm_map_t        zap_map);

static void             vm_map_copy_insert(
        vm_map_t        map,
        vm_map_entry_t  after_where,
        vm_map_copy_t   copy);

static kern_return_t    vm_map_copy_overwrite_unaligned(
        vm_map_t        dst_map,
        vm_map_entry_t  entry,
        vm_map_copy_t   copy,
        vm_map_address_t start,
        boolean_t       discard_on_success);

static kern_return_t    vm_map_copy_overwrite_aligned(
        vm_map_t        dst_map,
        vm_map_entry_t  tmp_entry,
        vm_map_copy_t   copy,
        vm_map_offset_t start,
        pmap_t          pmap);

static kern_return_t    vm_map_copyin_kernel_buffer(
        vm_map_t        src_map,
        vm_map_address_t src_addr,
        vm_map_size_t   len,
        boolean_t       src_destroy,
        vm_map_copy_t   *copy_result);  /* OUT */

static kern_return_t    vm_map_copyout_kernel_buffer(
        vm_map_t        map,
        vm_map_address_t *addr, /* IN/OUT */
        vm_map_copy_t   copy,
        vm_map_size_t   copy_size,
        boolean_t       overwrite,
        boolean_t       consume_on_success);

static void             vm_map_fork_share(
        vm_map_t        old_map,
        vm_map_entry_t  old_entry,
        vm_map_t        new_map);

static boolean_t        vm_map_fork_copy(
        vm_map_t        old_map,
        vm_map_entry_t  *old_entry_p,
        vm_map_t        new_map,
        int             vm_map_copyin_flags);

static kern_return_t    vm_map_wire_nested(
        vm_map_t                   map,
        vm_map_offset_t            start,
        vm_map_offset_t            end,
        vm_prot_t                  caller_prot,
        vm_tag_t                   tag,
        boolean_t                  user_wire,
        pmap_t                     map_pmap,
        vm_map_offset_t            pmap_addr,
        ppnum_t                    *physpage_p);

static kern_return_t    vm_map_unwire_nested(
        vm_map_t                   map,
        vm_map_offset_t            start,
        vm_map_offset_t            end,
        boolean_t                  user_wire,
        pmap_t                     map_pmap,
        vm_map_offset_t            pmap_addr);

static kern_return_t    vm_map_overwrite_submap_recurse(
        vm_map_t                   dst_map,
        vm_map_offset_t            dst_addr,
        vm_map_size_t              dst_size);

static kern_return_t    vm_map_copy_overwrite_nested(
        vm_map_t                   dst_map,
        vm_map_offset_t            dst_addr,
        vm_map_copy_t              copy,
        boolean_t                  interruptible,
        pmap_t                     pmap,
        boolean_t                  discard_on_success);

static kern_return_t    vm_map_remap_extract(
        vm_map_t                map,
        vm_map_offset_t         addr,
        vm_map_size_t           size,
        vm_prot_t               required_protection,
        boolean_t               copy,
        struct vm_map_header    *map_header,
        vm_prot_t               *cur_protection,
        vm_prot_t               *max_protection,
        vm_inherit_t            inheritance,
        vm_map_kernel_flags_t   vmk_flags);

static kern_return_t    vm_map_remap_range_allocate(
        vm_map_t                map,
        vm_map_address_t        *address,
        vm_map_size_t           size,
        vm_map_offset_t         mask,
        int                     flags,
        vm_map_kernel_flags_t   vmk_flags,
        vm_tag_t                tag,
        vm_map_entry_t          *map_entry);

static void             vm_map_region_look_for_page(
        vm_map_t                   map,
        vm_map_offset_t            va,
        vm_object_t                object,
        vm_object_offset_t         offset,
        int                        max_refcnt,
        unsigned short             depth,
        vm_region_extended_info_t  extended,
        mach_msg_type_number_t count);

static int              vm_map_region_count_obj_refs(
        vm_map_entry_t             entry,
        vm_object_t                object);


static kern_return_t    vm_map_willneed(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end);

static kern_return_t    vm_map_reuse_pages(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end);

static kern_return_t    vm_map_reusable_pages(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end);

static kern_return_t    vm_map_can_reuse(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end);

#if MACH_ASSERT
static kern_return_t    vm_map_pageout(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end);
#endif /* MACH_ASSERT */

kern_return_t vm_map_corpse_footprint_collect(
        vm_map_t        old_map,
        vm_map_entry_t  old_entry,
        vm_map_t        new_map);
void vm_map_corpse_footprint_collect_done(
        vm_map_t        new_map);
void vm_map_corpse_footprint_destroy(
        vm_map_t        map);
kern_return_t vm_map_corpse_footprint_query_page_info(
        vm_map_t        map,
        vm_map_offset_t va,
        int             *disposition_p);
void vm_map_footprint_query_page_info(
        vm_map_t        map,
        vm_map_entry_t  map_entry,
        vm_map_offset_t curr_s_offset,
        int             *disposition_p);

static const struct vm_map_entry vm_map_entry_template = {
        .behavior = VM_BEHAVIOR_DEFAULT,
        .inheritance = VM_INHERIT_DEFAULT,
};

pid_t find_largest_process_vm_map_entries(void);

/*
 * Macros to copy a vm_map_entry. We must be careful to correctly
 * manage the wired page count. vm_map_entry_copy() creates a new
 * map entry to the same memory - the wired count in the new entry
 * must be set to zero. vm_map_entry_copy_full() creates a new
 * entry that is identical to the old entry.  This preserves the
 * wire count; it's used for map splitting and zone changing in
 * vm_map_copyout.
 */

static inline void
vm_map_entry_copy_pmap_cs_assoc(
        vm_map_t map __unused,
        vm_map_entry_t new __unused,
        vm_map_entry_t old __unused)
{
        /* when pmap_cs is not enabled, assert as a sanity check */
        assert(new->pmap_cs_associated == FALSE);
}

/*
 * The "used_for_jit" flag was copied from OLD to NEW in vm_map_entry_copy().
 * But for security reasons on some platforms, we don't want the
 * new mapping to be "used for jit", so we reset the flag here.
 */
static inline void
vm_map_entry_copy_code_signing(
        vm_map_t map,
        vm_map_entry_t new,
        vm_map_entry_t old __unused)
{
        if (VM_MAP_POLICY_ALLOW_JIT_COPY(map)) {
                assert(new->used_for_jit == old->used_for_jit);
        } else {
                new->used_for_jit = FALSE;
        }
}

static inline void
vm_map_entry_copy(
        vm_map_t map,
        vm_map_entry_t new,
        vm_map_entry_t old)
{
        boolean_t _vmec_reserved = new->from_reserved_zone;
        *new = *old;
        new->is_shared = FALSE;
        new->needs_wakeup = FALSE;
        new->in_transition = FALSE;
        new->wired_count = 0;
        new->user_wired_count = 0;
        new->permanent = FALSE;
        vm_map_entry_copy_code_signing(map, new, old);
        vm_map_entry_copy_pmap_cs_assoc(map, new, old);
        new->from_reserved_zone = _vmec_reserved;
        if (new->iokit_acct) {
                assertf(!new->use_pmap, "old %p new %p\n", old, new);
                new->iokit_acct = FALSE;
                new->use_pmap = TRUE;
        }
        new->vme_resilient_codesign = FALSE;
        new->vme_resilient_media = FALSE;
        new->vme_atomic = FALSE;
        new->vme_no_copy_on_read = FALSE;
}

static inline void
vm_map_entry_copy_full(
        vm_map_entry_t new,
        vm_map_entry_t old)
{
        boolean_t _vmecf_reserved = new->from_reserved_zone;
        *new = *old;
        new->from_reserved_zone = _vmecf_reserved;
}

/*
 * Normal lock_read_to_write() returns FALSE/0 on failure.
 * These functions evaluate to zero on success and non-zero value on failure.
 */
__attribute__((always_inline))
int
vm_map_lock_read_to_write(vm_map_t map)
{
        if (lck_rw_lock_shared_to_exclusive(&(map)->lock)) {
                DTRACE_VM(vm_map_lock_upgrade);
                return 0;
        }
        return 1;
}

__attribute__((always_inline))
boolean_t
vm_map_try_lock(vm_map_t map)
{
        if (lck_rw_try_lock_exclusive(&(map)->lock)) {
                DTRACE_VM(vm_map_lock_w);
                return TRUE;
        }
        return FALSE;
}

__attribute__((always_inline))
boolean_t
vm_map_try_lock_read(vm_map_t map)
{
        if (lck_rw_try_lock_shared(&(map)->lock)) {
                DTRACE_VM(vm_map_lock_r);
                return TRUE;
        }
        return FALSE;
}

/*
 * Routines to get the page size the caller should
 * use while inspecting the target address space.
 * Use the "_safely" variant if the caller is dealing with a user-provided
 * array whose size depends on the page size, to avoid any overflow or
 * underflow of a user-allocated buffer.
 */
int
vm_self_region_page_shift_safely(
        vm_map_t target_map)
{
        int effective_page_shift = 0;

        if (PAGE_SIZE == (4096)) {
                /* x86_64 and 4k watches: always use 4k */
                return PAGE_SHIFT;
        }
        /* did caller provide an explicit page size for this thread to use? */
        effective_page_shift = thread_self_region_page_shift();
        if (effective_page_shift) {
                /* use the explicitly-provided page size */
                return effective_page_shift;
        }
        /* no explicit page size: use the caller's page size... */
        effective_page_shift = VM_MAP_PAGE_SHIFT(current_map());
        if (effective_page_shift == VM_MAP_PAGE_SHIFT(target_map)) {
                /* page size match: safe to use */
                return effective_page_shift;
        }
        /* page size mismatch */
        return -1;
}
int
vm_self_region_page_shift(
        vm_map_t target_map)
{
        int effective_page_shift;

        effective_page_shift = vm_self_region_page_shift_safely(target_map);
        if (effective_page_shift == -1) {
                /* no safe value but OK to guess for caller */
                effective_page_shift = MIN(VM_MAP_PAGE_SHIFT(current_map()),
                    VM_MAP_PAGE_SHIFT(target_map));
        }
        return effective_page_shift;
}


/*
 *      Decide if we want to allow processes to execute from their data or stack areas.
 *      override_nx() returns true if we do.  Data/stack execution can be enabled independently
 *      for 32 and 64 bit processes.  Set the VM_ABI_32 or VM_ABI_64 flags in allow_data_exec
 *      or allow_stack_exec to enable data execution for that type of data area for that particular
 *      ABI (or both by or'ing the flags together).  These are initialized in the architecture
 *      specific pmap files since the default behavior varies according to architecture.  The
 *      main reason it varies is because of the need to provide binary compatibility with old
 *      applications that were written before these restrictions came into being.  In the old
 *      days, an app could execute anything it could read, but this has slowly been tightened
 *      up over time.  The default behavior is:
 *
 *      32-bit PPC apps         may execute from both stack and data areas
 *      32-bit Intel apps       may exeucte from data areas but not stack
 *      64-bit PPC/Intel apps   may not execute from either data or stack
 *
 *      An application on any architecture may override these defaults by explicitly
 *      adding PROT_EXEC permission to the page in question with the mprotect(2)
 *      system call.  This code here just determines what happens when an app tries to
 *      execute from a page that lacks execute permission.
 *
 *      Note that allow_data_exec or allow_stack_exec may also be modified by sysctl to change the
 *      default behavior for both 32 and 64 bit apps on a system-wide basis. Furthermore,
 *      a Mach-O header flag bit (MH_NO_HEAP_EXECUTION) can be used to forcibly disallow
 *      execution from data areas for a particular binary even if the arch normally permits it. As
 *      a final wrinkle, a posix_spawn attribute flag can be used to negate this opt-in header bit
 *      to support some complicated use cases, notably browsers with out-of-process plugins that
 *      are not all NX-safe.
 */

extern int allow_data_exec, allow_stack_exec;

int
override_nx(vm_map_t map, uint32_t user_tag) /* map unused on arm */
{
        int current_abi;

        if (map->pmap == kernel_pmap) {
                return FALSE;
        }

        /*
         * Determine if the app is running in 32 or 64 bit mode.
         */

        if (vm_map_is_64bit(map)) {
                current_abi = VM_ABI_64;
        } else {
                current_abi = VM_ABI_32;
        }

        /*
         * Determine if we should allow the execution based on whether it's a
         * stack or data area and the current architecture.
         */

        if (user_tag == VM_MEMORY_STACK) {
                return allow_stack_exec & current_abi;
        }

        return (allow_data_exec & current_abi) && (map->map_disallow_data_exec == FALSE);
}


/*
 *      Virtual memory maps provide for the mapping, protection,
 *      and sharing of virtual memory objects.  In addition,
 *      this module provides for an efficient virtual copy of
 *      memory from one map to another.
 *
 *      Synchronization is required prior to most operations.
 *
 *      Maps consist of an ordered doubly-linked list of simple
 *      entries; a single hint is used to speed up lookups.
 *
 *      Sharing maps have been deleted from this version of Mach.
 *      All shared objects are now mapped directly into the respective
 *      maps.  This requires a change in the copy on write strategy;
 *      the asymmetric (delayed) strategy is used for shared temporary
 *      objects instead of the symmetric (shadow) strategy.  All maps
 *      are now "top level" maps (either task map, kernel map or submap
 *      of the kernel map).
 *
 *      Since portions of maps are specified by start/end addreses,
 *      which may not align with existing map entries, all
 *      routines merely "clip" entries to these start/end values.
 *      [That is, an entry is split into two, bordering at a
 *      start or end value.]  Note that these clippings may not
 *      always be necessary (as the two resulting entries are then
 *      not changed); however, the clipping is done for convenience.
 *      No attempt is currently made to "glue back together" two
 *      abutting entries.
 *
 *      The symmetric (shadow) copy strategy implements virtual copy
 *      by copying VM object references from one map to
 *      another, and then marking both regions as copy-on-write.
 *      It is important to note that only one writeable reference
 *      to a VM object region exists in any map when this strategy
 *      is used -- this means that shadow object creation can be
 *      delayed until a write operation occurs.  The symmetric (delayed)
 *      strategy allows multiple maps to have writeable references to
 *      the same region of a vm object, and hence cannot delay creating
 *      its copy objects.  See vm_object_copy_quickly() in vm_object.c.
 *      Copying of permanent objects is completely different; see
 *      vm_object_copy_strategically() in vm_object.c.
 */

static SECURITY_READ_ONLY_LATE(zone_t) vm_map_zone;       /* zone for vm_map structures */
static SECURITY_READ_ONLY_LATE(zone_t) vm_map_entry_reserved_zone; /* zone with reserve for non-blocking allocations */
static SECURITY_READ_ONLY_LATE(zone_t) vm_map_copy_zone;  /* zone for vm_map_copy structures */

SECURITY_READ_ONLY_LATE(zone_t)        vm_map_entry_zone; /* zone for vm_map_entry structures */
SECURITY_READ_ONLY_LATE(zone_t)        vm_map_holes_zone; /* zone for vm map holes (vm_map_links) structures */

#define VM_MAP_ZONE_NAME "maps"
#define VM_MAP_ZFLAGS ( \
  ZC_NOENCRYPT | \
  ZC_NOGC      | \
  ZC_NOGZALLOC | \
  ZC_ALLOW_FOREIGN)

#define VME_RESERVED_ZONE_NAME "Reserved VM map entries"
#define VM_MAP_RESERVED_ZFLAGS ( \
    ZC_NOENCRYPT          | \
    ZC_ALLOW_FOREIGN      | \
    ZC_NOCALLOUT          | \
    ZC_NOGZALLOC          | \
    ZC_KASAN_NOQUARANTINE | \
    ZC_NOGC)

#define VM_MAP_HOLES_ZONE_NAME "VM map holes"
#define VM_MAP_HOLES_ZFLAGS ( \
    ZC_NOENCRYPT | \
    ZC_NOGC      | \
    ZC_NOGZALLOC | \
    ZC_ALLOW_FOREIGN)

/*
 * Asserts that a vm_map_copy object is coming from the
 * vm_map_copy_zone to ensure that it isn't a fake constructed
 * anywhere else.
 */
static inline void
vm_map_copy_require(struct vm_map_copy *copy)
{
        zone_id_require(ZONE_ID_VM_MAP_COPY, sizeof(struct vm_map_copy), copy);
}

/*
 *      Placeholder object for submap operations.  This object is dropped
 *      into the range by a call to vm_map_find, and removed when
 *      vm_map_submap creates the submap.
 */

vm_object_t     vm_submap_object;

static __startup_data vm_offset_t      map_data;
static __startup_data vm_size_t        map_data_size;
static __startup_data vm_offset_t      kentry_data;
static __startup_data vm_size_t        kentry_data_size;
static __startup_data vm_offset_t      map_holes_data;
static __startup_data vm_size_t        map_holes_data_size;

#if XNU_TARGET_OS_OSX
#define         NO_COALESCE_LIMIT  ((1024 * 128) - 1)
#else /* XNU_TARGET_OS_OSX */
#define         NO_COALESCE_LIMIT  0
#endif /* XNU_TARGET_OS_OSX */

/* Skip acquiring locks if we're in the midst of a kernel core dump */
unsigned int not_in_kdp = 1;

unsigned int vm_map_set_cache_attr_count = 0;

kern_return_t
vm_map_set_cache_attr(
        vm_map_t        map,
        vm_map_offset_t va)
{
        vm_map_entry_t  map_entry;
        vm_object_t     object;
        kern_return_t   kr = KERN_SUCCESS;

        vm_map_lock_read(map);

        if (!vm_map_lookup_entry(map, va, &map_entry) ||
            map_entry->is_sub_map) {
                /*
                 * that memory is not properly mapped
                 */
                kr = KERN_INVALID_ARGUMENT;
                goto done;
        }
        object = VME_OBJECT(map_entry);

        if (object == VM_OBJECT_NULL) {
                /*
                 * there should be a VM object here at this point
                 */
                kr = KERN_INVALID_ARGUMENT;
                goto done;
        }
        vm_object_lock(object);
        object->set_cache_attr = TRUE;
        vm_object_unlock(object);

        vm_map_set_cache_attr_count++;
done:
        vm_map_unlock_read(map);

        return kr;
}


#if CONFIG_CODE_DECRYPTION
/*
 * vm_map_apple_protected:
 * This remaps the requested part of the object with an object backed by
 * the decrypting pager.
 * crypt_info contains entry points and session data for the crypt module.
 * The crypt_info block will be copied by vm_map_apple_protected. The data structures
 * referenced in crypt_info must remain valid until crypt_info->crypt_end() is called.
 */
kern_return_t
vm_map_apple_protected(
        vm_map_t                map,
        vm_map_offset_t         start,
        vm_map_offset_t         end,
        vm_object_offset_t      crypto_backing_offset,
        struct pager_crypt_info *crypt_info,
        uint32_t                cryptid)
{
        boolean_t       map_locked;
        kern_return_t   kr;
        vm_map_entry_t  map_entry;
        struct vm_map_entry tmp_entry;
        memory_object_t unprotected_mem_obj;
        vm_object_t     protected_object;
        vm_map_offset_t map_addr;
        vm_map_offset_t start_aligned, end_aligned;
        vm_object_offset_t      crypto_start, crypto_end;
        int             vm_flags;
        vm_map_kernel_flags_t vmk_flags;

        vm_flags = 0;
        vmk_flags = VM_MAP_KERNEL_FLAGS_NONE;

        map_locked = FALSE;
        unprotected_mem_obj = MEMORY_OBJECT_NULL;

        start_aligned = vm_map_trunc_page(start, PAGE_MASK_64);
        end_aligned = vm_map_round_page(end, PAGE_MASK_64);
        start_aligned = vm_map_trunc_page(start_aligned, VM_MAP_PAGE_MASK(map));
        end_aligned = vm_map_round_page(end_aligned, VM_MAP_PAGE_MASK(map));

#if __arm64__
        /*
         * "start" and "end" might be 4K-aligned but not 16K-aligned,
         * so we might have to loop and establish up to 3 mappings:
         *
         * + the first 16K-page, which might overlap with the previous
         *   4K-aligned mapping,
         * + the center,
         * + the last 16K-page, which might overlap with the next
         *   4K-aligned mapping.
         * Each of these mapping might be backed by a vnode pager (if
         * properly page-aligned) or a "fourk_pager", itself backed by a
         * vnode pager (if 4K-aligned but not page-aligned).
         */
#endif /* __arm64__ */

        map_addr = start_aligned;
        for (map_addr = start_aligned;
            map_addr < end;
            map_addr = tmp_entry.vme_end) {
                vm_map_lock(map);
                map_locked = TRUE;

                /* lookup the protected VM object */
                if (!vm_map_lookup_entry(map,
                    map_addr,
                    &map_entry) ||
                    map_entry->is_sub_map ||
                    VME_OBJECT(map_entry) == VM_OBJECT_NULL) {
                        /* that memory is not properly mapped */
                        kr = KERN_INVALID_ARGUMENT;
                        goto done;
                }

                /* ensure mapped memory is mapped as executable except
                 *  except for model decryption flow */
                if ((cryptid != CRYPTID_MODEL_ENCRYPTION) &&
                    !(map_entry->protection & VM_PROT_EXECUTE)) {
                        kr = KERN_INVALID_ARGUMENT;
                        goto done;
                }

                /* get the protected object to be decrypted */
                protected_object = VME_OBJECT(map_entry);
                if (protected_object == VM_OBJECT_NULL) {
                        /* there should be a VM object here at this point */
                        kr = KERN_INVALID_ARGUMENT;
                        goto done;
                }
                /* ensure protected object stays alive while map is unlocked */
                vm_object_reference(protected_object);

                /* limit the map entry to the area we want to cover */
                vm_map_clip_start(map, map_entry, start_aligned);
                vm_map_clip_end(map, map_entry, end_aligned);

                tmp_entry = *map_entry;
                map_entry = VM_MAP_ENTRY_NULL; /* not valid after unlocking map */
                vm_map_unlock(map);
                map_locked = FALSE;

                /*
                 * This map entry might be only partially encrypted
                 * (if not fully "page-aligned").
                 */
                crypto_start = 0;
                crypto_end = tmp_entry.vme_end - tmp_entry.vme_start;
                if (tmp_entry.vme_start < start) {
                        if (tmp_entry.vme_start != start_aligned) {
                                kr = KERN_INVALID_ADDRESS;
                        }
                        crypto_start += (start - tmp_entry.vme_start);
                }
                if (tmp_entry.vme_end > end) {
                        if (tmp_entry.vme_end != end_aligned) {
                                kr = KERN_INVALID_ADDRESS;
                        }
                        crypto_end -= (tmp_entry.vme_end - end);
                }

                /*
                 * This "extra backing offset" is needed to get the decryption
                 * routine to use the right key.  It adjusts for the possibly
                 * relative offset of an interposed "4K" pager...
                 */
                if (crypto_backing_offset == (vm_object_offset_t) -1) {
                        crypto_backing_offset = VME_OFFSET(&tmp_entry);
                }

                /*
                 * Lookup (and create if necessary) the protected memory object
                 * matching that VM object.
                 * If successful, this also grabs a reference on the memory object,
                 * to guarantee that it doesn't go away before we get a chance to map
                 * it.
                 */
                unprotected_mem_obj = apple_protect_pager_setup(
                        protected_object,
                        VME_OFFSET(&tmp_entry),
                        crypto_backing_offset,
                        crypt_info,
                        crypto_start,
                        crypto_end);

                /* release extra ref on protected object */
                vm_object_deallocate(protected_object);

                if (unprotected_mem_obj == NULL) {
                        kr = KERN_FAILURE;
                        goto done;
                }

                vm_flags = VM_FLAGS_FIXED | VM_FLAGS_OVERWRITE;
                /* can overwrite an immutable mapping */
                vmk_flags.vmkf_overwrite_immutable = TRUE;
#if __arm64__
                if (tmp_entry.used_for_jit &&
                    (VM_MAP_PAGE_SHIFT(map) != FOURK_PAGE_SHIFT ||
                    PAGE_SHIFT != FOURK_PAGE_SHIFT) &&
                    fourk_binary_compatibility_unsafe &&
                    fourk_binary_compatibility_allow_wx) {
                        printf("** FOURK_COMPAT [%d]: "
                            "allowing write+execute at 0x%llx\n",
                            proc_selfpid(), tmp_entry.vme_start);
                        vmk_flags.vmkf_map_jit = TRUE;
                }
#endif /* __arm64__ */

                /* map this memory object in place of the current one */
                map_addr = tmp_entry.vme_start;
                kr = vm_map_enter_mem_object(map,
                    &map_addr,
                    (tmp_entry.vme_end -
                    tmp_entry.vme_start),
                    (mach_vm_offset_t) 0,
                    vm_flags,
                    vmk_flags,
                    VM_KERN_MEMORY_NONE,
                    (ipc_port_t)(uintptr_t) unprotected_mem_obj,
                    0,
                    TRUE,
                    tmp_entry.protection,
                    tmp_entry.max_protection,
                    tmp_entry.inheritance);
                assertf(kr == KERN_SUCCESS,
                    "kr = 0x%x\n", kr);
                assertf(map_addr == tmp_entry.vme_start,
                    "map_addr=0x%llx vme_start=0x%llx tmp_entry=%p\n",
                    (uint64_t)map_addr,
                    (uint64_t) tmp_entry.vme_start,
                    &tmp_entry);

#if VM_MAP_DEBUG_APPLE_PROTECT
                if (vm_map_debug_apple_protect) {
                        printf("APPLE_PROTECT: map %p [0x%llx:0x%llx] pager %p:"
                            " backing:[object:%p,offset:0x%llx,"
                            "crypto_backing_offset:0x%llx,"
                            "crypto_start:0x%llx,crypto_end:0x%llx]\n",
                            map,
                            (uint64_t) map_addr,
                            (uint64_t) (map_addr + (tmp_entry.vme_end -
                            tmp_entry.vme_start)),
                            unprotected_mem_obj,
                            protected_object,
                            VME_OFFSET(&tmp_entry),
                            crypto_backing_offset,
                            crypto_start,
                            crypto_end);
                }
#endif /* VM_MAP_DEBUG_APPLE_PROTECT */

                /*
                 * Release the reference obtained by
                 * apple_protect_pager_setup().
                 * The mapping (if it succeeded) is now holding a reference on
                 * the memory object.
                 */
                memory_object_deallocate(unprotected_mem_obj);
                unprotected_mem_obj = MEMORY_OBJECT_NULL;

                /* continue with next map entry */
                crypto_backing_offset += (tmp_entry.vme_end -
                    tmp_entry.vme_start);
                crypto_backing_offset -= crypto_start;
        }
        kr = KERN_SUCCESS;

done:
        if (map_locked) {
                vm_map_unlock(map);
        }
        return kr;
}
#endif  /* CONFIG_CODE_DECRYPTION */


LCK_GRP_DECLARE(vm_map_lck_grp, "vm_map");
LCK_ATTR_DECLARE(vm_map_lck_attr, 0, 0);
LCK_ATTR_DECLARE(vm_map_lck_rw_attr, 0, LCK_ATTR_DEBUG);

#if XNU_TARGET_OS_OSX
int malloc_no_cow = 0;
#else /* XNU_TARGET_OS_OSX */
int malloc_no_cow = 1;
#endif /* XNU_TARGET_OS_OSX */
uint64_t vm_memory_malloc_no_cow_mask = 0ULL;
#if DEBUG
int vm_check_map_sanity = 0;
#endif

/*
 *      vm_map_init:
 *
 *      Initialize the vm_map module.  Must be called before
 *      any other vm_map routines.
 *
 *      Map and entry structures are allocated from zones -- we must
 *      initialize those zones.
 *
 *      There are three zones of interest:
 *
 *      vm_map_zone:            used to allocate maps.
 *      vm_map_entry_zone:      used to allocate map entries.
 *      vm_map_entry_reserved_zone:     fallback zone for kernel map entries
 *
 *      The kernel allocates map entries from a special zone that is initially
 *      "crammed" with memory.  It would be difficult (perhaps impossible) for
 *      the kernel to allocate more memory to a entry zone when it became
 *      empty since the very act of allocating memory implies the creation
 *      of a new entry.
 */
__startup_func
void
vm_map_init(void)
{
        const char *mez_name = "VM map entries";


#if MACH_ASSERT
        PE_parse_boot_argn("debug4k_filter", &debug4k_filter,
            sizeof(debug4k_filter));
#endif /* MACH_ASSERT */

        vm_map_zone = zone_create(VM_MAP_ZONE_NAME, sizeof(struct _vm_map),
            VM_MAP_ZFLAGS);

        vm_map_entry_zone = zone_create(mez_name, sizeof(struct vm_map_entry),
            ZC_NOENCRYPT | ZC_NOGZALLOC | ZC_NOCALLOUT);

        /*
         * Don't quarantine because we always need elements available
         * Disallow GC on this zone... to aid the GC.
         */
        vm_map_entry_reserved_zone = zone_create_ext(VME_RESERVED_ZONE_NAME,
            sizeof(struct vm_map_entry), VM_MAP_RESERVED_ZFLAGS,
            ZONE_ID_ANY, ^(zone_t z) {
                zone_set_noexpand(z, 64 * kentry_data_size);
        });

        vm_map_copy_zone = zone_create_ext("VM map copies", sizeof(struct vm_map_copy),
            ZC_NOENCRYPT | ZC_CACHING, ZONE_ID_VM_MAP_COPY, NULL);

        vm_map_holes_zone = zone_create(VM_MAP_HOLES_ZONE_NAME,
            sizeof(struct vm_map_links), VM_MAP_HOLES_ZFLAGS);

        /*
         * Add the stolen memory to zones, adjust zone size and stolen counts.
         */
        zcram(vm_map_zone, map_data, map_data_size);
        zcram(vm_map_entry_reserved_zone, kentry_data, kentry_data_size);
        zcram(vm_map_holes_zone, map_holes_data, map_holes_data_size);

        /*
         * Since these are covered by zones, remove them from stolen page accounting.
         */
        VM_PAGE_MOVE_STOLEN(atop_64(map_data_size) + atop_64(kentry_data_size) + atop_64(map_holes_data_size));

#if VM_MAP_DEBUG_APPLE_PROTECT
        PE_parse_boot_argn("vm_map_debug_apple_protect",
            &vm_map_debug_apple_protect,
            sizeof(vm_map_debug_apple_protect));
#endif /* VM_MAP_DEBUG_APPLE_PROTECT */
#if VM_MAP_DEBUG_APPLE_FOURK
        PE_parse_boot_argn("vm_map_debug_fourk",
            &vm_map_debug_fourk,
            sizeof(vm_map_debug_fourk));
#endif /* VM_MAP_DEBUG_FOURK */
        PE_parse_boot_argn("vm_map_executable_immutable",
            &vm_map_executable_immutable,
            sizeof(vm_map_executable_immutable));
        PE_parse_boot_argn("vm_map_executable_immutable_verbose",
            &vm_map_executable_immutable_verbose,
            sizeof(vm_map_executable_immutable_verbose));

        PE_parse_boot_argn("malloc_no_cow",
            &malloc_no_cow,
            sizeof(malloc_no_cow));
        if (malloc_no_cow) {
                vm_memory_malloc_no_cow_mask = 0ULL;
                vm_memory_malloc_no_cow_mask |= 1ULL << VM_MEMORY_MALLOC;
                vm_memory_malloc_no_cow_mask |= 1ULL << VM_MEMORY_MALLOC_SMALL;
                vm_memory_malloc_no_cow_mask |= 1ULL << VM_MEMORY_MALLOC_MEDIUM;
                vm_memory_malloc_no_cow_mask |= 1ULL << VM_MEMORY_MALLOC_LARGE;
//              vm_memory_malloc_no_cow_mask |= 1ULL << VM_MEMORY_MALLOC_HUGE;
//              vm_memory_malloc_no_cow_mask |= 1ULL << VM_MEMORY_REALLOC;
                vm_memory_malloc_no_cow_mask |= 1ULL << VM_MEMORY_MALLOC_TINY;
                vm_memory_malloc_no_cow_mask |= 1ULL << VM_MEMORY_MALLOC_LARGE_REUSABLE;
                vm_memory_malloc_no_cow_mask |= 1ULL << VM_MEMORY_MALLOC_LARGE_REUSED;
                vm_memory_malloc_no_cow_mask |= 1ULL << VM_MEMORY_MALLOC_NANO;
//              vm_memory_malloc_no_cow_mask |= 1ULL << VM_MEMORY_TCMALLOC;
                PE_parse_boot_argn("vm_memory_malloc_no_cow_mask",
                    &vm_memory_malloc_no_cow_mask,
                    sizeof(vm_memory_malloc_no_cow_mask));
        }

#if DEBUG
        PE_parse_boot_argn("vm_check_map_sanity", &vm_check_map_sanity, sizeof(vm_check_map_sanity));
        if (vm_check_map_sanity) {
                kprintf("VM sanity checking enabled\n");
        } else {
                kprintf("VM sanity checking disabled. Set bootarg vm_check_map_sanity=1 to enable\n");
        }
#endif /* DEBUG */

#if DEVELOPMENT || DEBUG
        PE_parse_boot_argn("panic_on_unsigned_execute",
            &panic_on_unsigned_execute,
            sizeof(panic_on_unsigned_execute));
#endif /* DEVELOPMENT || DEBUG */
}

__startup_func
static void
vm_map_steal_memory(void)
{
        uint16_t kentry_initial_pages;

        map_data_size = zone_get_foreign_alloc_size(VM_MAP_ZONE_NAME,
            sizeof(struct _vm_map), VM_MAP_ZFLAGS, 1);

        /*
         * kentry_initial_pages corresponds to the number of kernel map entries
         * required during bootstrap until the asynchronous replenishment
         * scheme is activated and/or entries are available from the general
         * map entry pool.
         */
#if     defined(__LP64__)
        kentry_initial_pages = 10;
#else
        kentry_initial_pages = 6;
#endif

#if CONFIG_GZALLOC
        /* If using the guard allocator, reserve more memory for the kernel
         * reserved map entry pool.
         */
        if (gzalloc_enabled()) {
                kentry_initial_pages *= 1024;
        }
#endif

        kentry_data_size = zone_get_foreign_alloc_size(VME_RESERVED_ZONE_NAME,
            sizeof(struct vm_map_entry), VM_MAP_RESERVED_ZFLAGS,
            kentry_initial_pages);

        map_holes_data_size = zone_get_foreign_alloc_size(VM_MAP_HOLES_ZONE_NAME,
            sizeof(struct vm_map_links), VM_MAP_HOLES_ZFLAGS,
            kentry_initial_pages);

        /*
         * Steal a contiguous range of memory so that a simple range check
         * can validate foreign addresses being freed/crammed to these
         * zones
         */
        vm_size_t total_size;
        if (os_add3_overflow(map_data_size, kentry_data_size,
            map_holes_data_size, &total_size)) {
                panic("vm_map_steal_memory: overflow in amount of memory requested");
        }
        map_data = zone_foreign_mem_init(total_size);
        kentry_data = map_data + map_data_size;
        map_holes_data = kentry_data + kentry_data_size;
}
STARTUP(PMAP_STEAL, STARTUP_RANK_FIRST, vm_map_steal_memory);

boolean_t vm_map_supports_hole_optimization = FALSE;

void
vm_kernel_reserved_entry_init(void)
{
        zone_prio_refill_configure(vm_map_entry_reserved_zone);

        /*
         * Once we have our replenish thread set up, we can start using the vm_map_holes zone.
         */
        zone_prio_refill_configure(vm_map_holes_zone);
        vm_map_supports_hole_optimization = TRUE;
}

void
vm_map_disable_hole_optimization(vm_map_t map)
{
        vm_map_entry_t  head_entry, hole_entry, next_hole_entry;

        if (map->holelistenabled) {
                head_entry = hole_entry = CAST_TO_VM_MAP_ENTRY(map->holes_list);

                while (hole_entry != NULL) {
                        next_hole_entry = hole_entry->vme_next;

                        hole_entry->vme_next = NULL;
                        hole_entry->vme_prev = NULL;
                        zfree(vm_map_holes_zone, hole_entry);

                        if (next_hole_entry == head_entry) {
                                hole_entry = NULL;
                        } else {
                                hole_entry = next_hole_entry;
                        }
                }

                map->holes_list = NULL;
                map->holelistenabled = FALSE;

                map->first_free = vm_map_first_entry(map);
                SAVE_HINT_HOLE_WRITE(map, NULL);
        }
}

boolean_t
vm_kernel_map_is_kernel(vm_map_t map)
{
        return map->pmap == kernel_pmap;
}

/*
 *      vm_map_create:
 *
 *      Creates and returns a new empty VM map with
 *      the given physical map structure, and having
 *      the given lower and upper address bounds.
 */

vm_map_t
vm_map_create(
        pmap_t          pmap,
        vm_map_offset_t min,
        vm_map_offset_t max,
        boolean_t       pageable)
{
        int options;

        options = 0;
        if (pageable) {
                options |= VM_MAP_CREATE_PAGEABLE;
        }
        return vm_map_create_options(pmap, min, max, options);
}

vm_map_t
vm_map_create_options(
        pmap_t          pmap,
        vm_map_offset_t min,
        vm_map_offset_t max,
        int             options)
{
        vm_map_t        result;
        struct vm_map_links     *hole_entry = NULL;

        if (options & ~(VM_MAP_CREATE_ALL_OPTIONS)) {
                /* unknown option */
                return VM_MAP_NULL;
        }

        result = (vm_map_t) zalloc(vm_map_zone);
        if (result == VM_MAP_NULL) {
                panic("vm_map_create");
        }

        vm_map_first_entry(result) = vm_map_to_entry(result);
        vm_map_last_entry(result)  = vm_map_to_entry(result);
        result->hdr.nentries = 0;
        if (options & VM_MAP_CREATE_PAGEABLE) {
                result->hdr.entries_pageable = TRUE;
        } else {
                result->hdr.entries_pageable = FALSE;
        }

        vm_map_store_init( &(result->hdr));

        result->hdr.page_shift = PAGE_SHIFT;

        result->size = 0;
        result->user_wire_limit = MACH_VM_MAX_ADDRESS;  /* default limit is unlimited */
        result->user_wire_size  = 0;
#if XNU_TARGET_OS_OSX
        result->vmmap_high_start = 0;
#endif
        os_ref_init_count(&result->map_refcnt, &map_refgrp, 1);
#if     TASK_SWAPPER
        result->res_count = 1;
        result->sw_state = MAP_SW_IN;
#endif  /* TASK_SWAPPER */
        result->pmap = pmap;
        result->min_offset = min;
        result->max_offset = max;
        result->wiring_required = FALSE;
        result->no_zero_fill = FALSE;
        result->mapped_in_other_pmaps = FALSE;
        result->wait_for_space = FALSE;
        result->switch_protect = FALSE;
        result->disable_vmentry_reuse = FALSE;
        result->map_disallow_data_exec = FALSE;
        result->is_nested_map = FALSE;
        result->map_disallow_new_exec = FALSE;
        result->terminated = FALSE;
        result->cs_enforcement = FALSE;
        result->highest_entry_end = 0;
        result->first_free = vm_map_to_entry(result);
        result->hint = vm_map_to_entry(result);
        result->jit_entry_exists = FALSE;
        result->is_alien = FALSE;
        result->reserved_regions = FALSE;

        /* "has_corpse_footprint" and "holelistenabled" are mutually exclusive */
        if (options & VM_MAP_CREATE_CORPSE_FOOTPRINT) {
                result->has_corpse_footprint = TRUE;
                result->holelistenabled = FALSE;
                result->vmmap_corpse_footprint = NULL;
        } else {
                result->has_corpse_footprint = FALSE;
                if (vm_map_supports_hole_optimization) {
                        hole_entry = zalloc(vm_map_holes_zone);

                        hole_entry->start = min;
#if defined(__arm__) || defined(__arm64__)
                        hole_entry->end = result->max_offset;
#else
                        hole_entry->end = (max > (vm_map_offset_t)MACH_VM_MAX_ADDRESS) ? max : (vm_map_offset_t)MACH_VM_MAX_ADDRESS;
#endif
                        result->holes_list = result->hole_hint = hole_entry;
                        hole_entry->prev = hole_entry->next = CAST_TO_VM_MAP_ENTRY(hole_entry);
                        result->holelistenabled = TRUE;
                } else {
                        result->holelistenabled = FALSE;
                }
        }

        vm_map_lock_init(result);
        lck_mtx_init_ext(&result->s_lock, &result->s_lock_ext, &vm_map_lck_grp, &vm_map_lck_attr);

        return result;
}

vm_map_size_t
vm_map_adjusted_size(vm_map_t map)
{
        struct vm_reserved_region *regions = NULL;
        size_t num_regions = 0;
        mach_vm_size_t  reserved_size = 0, map_size = 0;

        if (map == NULL || (map->size == 0)) {
                return 0;
        }

        map_size = map->size;

        if (map->reserved_regions == FALSE || !vm_map_is_exotic(map) || map->terminated) {
                /*
                 * No special reserved regions or not an exotic map or the task
                 * is terminating and these special regions might have already
                 * been deallocated.
                 */
                return map_size;
        }

        num_regions = ml_get_vm_reserved_regions(vm_map_is_64bit(map), &regions);
        assert((num_regions == 0) || (num_regions > 0 && regions != NULL));

        while (num_regions) {
                reserved_size += regions[--num_regions].vmrr_size;
        }

        /*
         * There are a few places where the map is being switched out due to
         * 'termination' without that bit being set (e.g. exec and corpse purging).
         * In those cases, we could have the map's regions being deallocated on
         * a core while some accounting process is trying to get the map's size.
         * So this assert can't be enabled till all those places are uniform in
         * their use of the 'map->terminated' bit.
         *
         * assert(map_size >= reserved_size);
         */

        return (map_size >= reserved_size) ? (map_size - reserved_size) : map_size;
}

/*
 *      vm_map_entry_create:    [ internal use only ]
 *
 *      Allocates a VM map entry for insertion in the
 *      given map (or map copy).  No fields are filled.
 */
#define vm_map_entry_create(map, map_locked)    _vm_map_entry_create(&(map)->hdr, map_locked)

#define vm_map_copy_entry_create(copy, map_locked)                                      \
        _vm_map_entry_create(&(copy)->cpy_hdr, map_locked)
unsigned reserved_zalloc_count, nonreserved_zalloc_count;

static vm_map_entry_t
_vm_map_entry_create(
        struct vm_map_header    *map_header, boolean_t __unused map_locked)
{
        zone_t  zone;
        vm_map_entry_t  entry;

        zone = vm_map_entry_zone;

        assert(map_header->entries_pageable ? !map_locked : TRUE);

        if (map_header->entries_pageable) {
                entry = (vm_map_entry_t) zalloc(zone);
        } else {
                entry = (vm_map_entry_t) zalloc_noblock(zone);

                if (entry == VM_MAP_ENTRY_NULL) {
                        zone = vm_map_entry_reserved_zone;
                        entry = (vm_map_entry_t) zalloc(zone);
                        OSAddAtomic(1, &reserved_zalloc_count);
                } else {
                        OSAddAtomic(1, &nonreserved_zalloc_count);
                }
        }

        if (entry == VM_MAP_ENTRY_NULL) {
                panic("vm_map_entry_create");
        }
        *entry = vm_map_entry_template;
        entry->from_reserved_zone = (zone == vm_map_entry_reserved_zone);

        vm_map_store_update((vm_map_t) NULL, entry, VM_MAP_ENTRY_CREATE);
#if     MAP_ENTRY_CREATION_DEBUG
        entry->vme_creation_maphdr = map_header;
        backtrace(&entry->vme_creation_bt[0],
            (sizeof(entry->vme_creation_bt) / sizeof(uintptr_t)), NULL);
#endif
        return entry;
}

/*
 *      vm_map_entry_dispose:   [ internal use only ]
 *
 *      Inverse of vm_map_entry_create.
 *
 *      write map lock held so no need to
 *      do anything special to insure correctness
 *      of the stores
 */
#define vm_map_entry_dispose(map, entry)                        \
        _vm_map_entry_dispose(&(map)->hdr, (entry))

#define vm_map_copy_entry_dispose(copy, entry) \
        _vm_map_entry_dispose(&(copy)->cpy_hdr, (entry))

static void
_vm_map_entry_dispose(
        struct vm_map_header    *map_header,
        vm_map_entry_t          entry)
{
        zone_t          zone;

        if (map_header->entries_pageable || !(entry->from_reserved_zone)) {
                zone = vm_map_entry_zone;
        } else {
                zone = vm_map_entry_reserved_zone;
        }

        if (!map_header->entries_pageable) {
                if (zone == vm_map_entry_zone) {
                        OSAddAtomic(-1, &nonreserved_zalloc_count);
                } else {
                        OSAddAtomic(-1, &reserved_zalloc_count);
                }
        }

        zfree(zone, entry);
}

#if MACH_ASSERT
static boolean_t first_free_check = FALSE;
boolean_t
first_free_is_valid(
        vm_map_t        map)
{
        if (!first_free_check) {
                return TRUE;
        }

        return first_free_is_valid_store( map );
}
#endif /* MACH_ASSERT */


#define vm_map_copy_entry_link(copy, after_where, entry)                \
        _vm_map_store_entry_link(&(copy)->cpy_hdr, after_where, (entry))

#define vm_map_copy_entry_unlink(copy, entry)                           \
        _vm_map_store_entry_unlink(&(copy)->cpy_hdr, (entry))

#if     MACH_ASSERT && TASK_SWAPPER
/*
 *      vm_map_res_reference:
 *
 *      Adds another valid residence count to the given map.
 *
 *      Map is locked so this function can be called from
 *      vm_map_swapin.
 *
 */
void
vm_map_res_reference(vm_map_t map)
{
        /* assert map is locked */
        assert(map->res_count >= 0);
        assert(os_ref_get_count(&map->map_refcnt) >= map->res_count);
        if (map->res_count == 0) {
                lck_mtx_unlock(&map->s_lock);
                vm_map_lock(map);
                vm_map_swapin(map);
                lck_mtx_lock(&map->s_lock);
                ++map->res_count;
                vm_map_unlock(map);
        } else {
                ++map->res_count;
        }
}

/*
 *      vm_map_reference_swap:
 *
 *      Adds valid reference and residence counts to the given map.
 *
 *      The map may not be in memory (i.e. zero residence count).
 *
 */
void
vm_map_reference_swap(vm_map_t map)
{
        assert(map != VM_MAP_NULL);
        lck_mtx_lock(&map->s_lock);
        assert(map->res_count >= 0);
        assert(os_ref_get_count(&map->map_refcnt) >= map->res_count);
        os_ref_retain_locked(&map->map_refcnt);
        vm_map_res_reference(map);
        lck_mtx_unlock(&map->s_lock);
}

/*
 *      vm_map_res_deallocate:
 *
 *      Decrement residence count on a map; possibly causing swapout.
 *
 *      The map must be in memory (i.e. non-zero residence count).
 *
 *      The map is locked, so this function is callable from vm_map_deallocate.
 *
 */
void
vm_map_res_deallocate(vm_map_t map)
{
        assert(map->res_count > 0);
        if (--map->res_count == 0) {
                lck_mtx_unlock(&map->s_lock);
                vm_map_lock(map);
                vm_map_swapout(map);
                vm_map_unlock(map);
                lck_mtx_lock(&map->s_lock);
        }
        assert(os_ref_get_count(&map->map_refcnt) >= map->res_count);
}
#endif  /* MACH_ASSERT && TASK_SWAPPER */

/*
 *      vm_map_destroy:
 *
 *      Actually destroy a map.
 */
void
vm_map_destroy(
        vm_map_t        map,
        int             flags)
{
        vm_map_lock(map);

        /* final cleanup: no need to unnest shared region */
        flags |= VM_MAP_REMOVE_NO_UNNESTING;
        /* final cleanup: ok to remove immutable mappings */
        flags |= VM_MAP_REMOVE_IMMUTABLE;
        /* final cleanup: allow gaps in range */
        flags |= VM_MAP_REMOVE_GAPS_OK;

        /* clean up regular map entries */
        (void) vm_map_delete(map, map->min_offset, map->max_offset,
            flags, VM_MAP_NULL);
        /* clean up leftover special mappings (commpage, GPU carveout, etc...) */
#if     !defined(__arm__)
        (void) vm_map_delete(map, 0x0, 0xFFFFFFFFFFFFF000ULL,
            flags, VM_MAP_NULL);
#endif /* !__arm__ */

        vm_map_disable_hole_optimization(map);
        vm_map_corpse_footprint_destroy(map);

        vm_map_unlock(map);

        assert(map->hdr.nentries == 0);

        if (map->pmap) {
                pmap_destroy(map->pmap);
        }

        if (vm_map_lck_attr.lck_attr_val & LCK_ATTR_DEBUG) {
                /*
                 * If lock debugging is enabled the mutexes get tagged as LCK_MTX_TAG_INDIRECT.
                 * And this is regardless of whether the lck_mtx_ext_t is embedded in the
                 * structure or kalloc'ed via lck_mtx_init.
                 * An example is s_lock_ext within struct _vm_map.
                 *
                 * A lck_mtx_destroy on such a mutex will attempt a kfree and panic. We
                 * can add another tag to detect embedded vs alloc'ed indirect external
                 * mutexes but that'll be additional checks in the lock path and require
                 * updating dependencies for the old vs new tag.
                 *
                 * Since the kfree() is for LCK_MTX_TAG_INDIRECT mutexes and that tag is applied
                 * just when lock debugging is ON, we choose to forego explicitly destroying
                 * the vm_map mutex and rw lock and, as a consequence, will overflow the reference
                 * count on vm_map_lck_grp, which has no serious side-effect.
                 */
        } else {
                lck_rw_destroy(&(map)->lock, &vm_map_lck_grp);
                lck_mtx_destroy(&(map)->s_lock, &vm_map_lck_grp);
        }

        zfree(vm_map_zone, map);
}

/*
 * Returns pid of the task with the largest number of VM map entries.
 * Used in the zone-map-exhaustion jetsam path.
 */
pid_t
find_largest_process_vm_map_entries(void)
{
        pid_t victim_pid = -1;
        int max_vm_map_entries = 0;
        task_t task = TASK_NULL;
        queue_head_t *task_list = &tasks;

        lck_mtx_lock(&tasks_threads_lock);
        queue_iterate(task_list, task, task_t, tasks) {
                if (task == kernel_task || !task->active) {
                        continue;
                }

                vm_map_t task_map = task->map;
                if (task_map != VM_MAP_NULL) {
                        int task_vm_map_entries = task_map->hdr.nentries;
                        if (task_vm_map_entries > max_vm_map_entries) {
                                max_vm_map_entries = task_vm_map_entries;
                                victim_pid = pid_from_task(task);
                        }
                }
        }
        lck_mtx_unlock(&tasks_threads_lock);

        printf("zone_map_exhaustion: victim pid %d, vm region count: %d\n", victim_pid, max_vm_map_entries);
        return victim_pid;
}

#if     TASK_SWAPPER
/*
 * vm_map_swapin/vm_map_swapout
 *
 * Swap a map in and out, either referencing or releasing its resources.
 * These functions are internal use only; however, they must be exported
 * because they may be called from macros, which are exported.
 *
 * In the case of swapout, there could be races on the residence count,
 * so if the residence count is up, we return, assuming that a
 * vm_map_deallocate() call in the near future will bring us back.
 *
 * Locking:
 *      -- We use the map write lock for synchronization among races.
 *      -- The map write lock, and not the simple s_lock, protects the
 *         swap state of the map.
 *      -- If a map entry is a share map, then we hold both locks, in
 *         hierarchical order.
 *
 * Synchronization Notes:
 *      1) If a vm_map_swapin() call happens while swapout in progress, it
 *      will block on the map lock and proceed when swapout is through.
 *      2) A vm_map_reference() call at this time is illegal, and will
 *      cause a panic.  vm_map_reference() is only allowed on resident
 *      maps, since it refuses to block.
 *      3) A vm_map_swapin() call during a swapin will block, and
 *      proceeed when the first swapin is done, turning into a nop.
 *      This is the reason the res_count is not incremented until
 *      after the swapin is complete.
 *      4) There is a timing hole after the checks of the res_count, before
 *      the map lock is taken, during which a swapin may get the lock
 *      before a swapout about to happen.  If this happens, the swapin
 *      will detect the state and increment the reference count, causing
 *      the swapout to be a nop, thereby delaying it until a later
 *      vm_map_deallocate.  If the swapout gets the lock first, then
 *      the swapin will simply block until the swapout is done, and
 *      then proceed.
 *
 * Because vm_map_swapin() is potentially an expensive operation, it
 * should be used with caution.
 *
 * Invariants:
 *      1) A map with a residence count of zero is either swapped, or
 *         being swapped.
 *      2) A map with a non-zero residence count is either resident,
 *         or being swapped in.
 */

int vm_map_swap_enable = 1;

void
vm_map_swapin(vm_map_t map)
{
        vm_map_entry_t entry;

        if (!vm_map_swap_enable) {      /* debug */
                return;
        }

        /*
         * Map is locked
         * First deal with various races.
         */
        if (map->sw_state == MAP_SW_IN) {
                /*
                 * we raced with swapout and won.  Returning will incr.
                 * the res_count, turning the swapout into a nop.
                 */
                return;
        }

        /*
         * The residence count must be zero.  If we raced with another
         * swapin, the state would have been IN; if we raced with a
         * swapout (after another competing swapin), we must have lost
         * the race to get here (see above comment), in which case
         * res_count is still 0.
         */
        assert(map->res_count == 0);

        /*
         * There are no intermediate states of a map going out or
         * coming in, since the map is locked during the transition.
         */
        assert(map->sw_state == MAP_SW_OUT);

        /*
         * We now operate upon each map entry.  If the entry is a sub-
         * or share-map, we call vm_map_res_reference upon it.
         * If the entry is an object, we call vm_object_res_reference
         * (this may iterate through the shadow chain).
         * Note that we hold the map locked the entire time,
         * even if we get back here via a recursive call in
         * vm_map_res_reference.
         */
        entry = vm_map_first_entry(map);

        while (entry != vm_map_to_entry(map)) {
                if (VME_OBJECT(entry) != VM_OBJECT_NULL) {
                        if (entry->is_sub_map) {
                                vm_map_t lmap = VME_SUBMAP(entry);
                                lck_mtx_lock(&lmap->s_lock);
                                vm_map_res_reference(lmap);
                                lck_mtx_unlock(&lmap->s_lock);
                        } else {
                                vm_object_t object = VME_OBEJCT(entry);
                                vm_object_lock(object);
                                /*
                                 * This call may iterate through the
                                 * shadow chain.
                                 */
                                vm_object_res_reference(object);
                                vm_object_unlock(object);
                        }
                }
                entry = entry->vme_next;
        }
        assert(map->sw_state == MAP_SW_OUT);
        map->sw_state = MAP_SW_IN;
}

void
vm_map_swapout(vm_map_t map)
{
        vm_map_entry_t entry;

        /*
         * Map is locked
         * First deal with various races.
         * If we raced with a swapin and lost, the residence count
         * will have been incremented to 1, and we simply return.
         */
        lck_mtx_lock(&map->s_lock);
        if (map->res_count != 0) {
                lck_mtx_unlock(&map->s_lock);
                return;
        }
        lck_mtx_unlock(&map->s_lock);

        /*
         * There are no intermediate states of a map going out or
         * coming in, since the map is locked during the transition.
         */
        assert(map->sw_state == MAP_SW_IN);

        if (!vm_map_swap_enable) {
                return;
        }

        /*
         * We now operate upon each map entry.  If the entry is a sub-
         * or share-map, we call vm_map_res_deallocate upon it.
         * If the entry is an object, we call vm_object_res_deallocate
         * (this may iterate through the shadow chain).
         * Note that we hold the map locked the entire time,
         * even if we get back here via a recursive call in
         * vm_map_res_deallocate.
         */
        entry = vm_map_first_entry(map);

        while (entry != vm_map_to_entry(map)) {
                if (VME_OBJECT(entry) != VM_OBJECT_NULL) {
                        if (entry->is_sub_map) {
                                vm_map_t lmap = VME_SUBMAP(entry);
                                lck_mtx_lock(&lmap->s_lock);
                                vm_map_res_deallocate(lmap);
                                lck_mtx_unlock(&lmap->s_lock);
                        } else {
                                vm_object_t object = VME_OBJECT(entry);
                                vm_object_lock(object);
                                /*
                                 * This call may take a long time,
                                 * since it could actively push
                                 * out pages (if we implement it
                                 * that way).
                                 */
                                vm_object_res_deallocate(object);
                                vm_object_unlock(object);
                        }
                }
                entry = entry->vme_next;
        }
        assert(map->sw_state == MAP_SW_IN);
        map->sw_state = MAP_SW_OUT;
}

#endif  /* TASK_SWAPPER */

/*
 *      vm_map_lookup_entry:    [ internal use only ]
 *
 *      Calls into the vm map store layer to find the map
 *      entry containing (or immediately preceding) the
 *      specified address in the given map; the entry is returned
 *      in the "entry" parameter.  The boolean
 *      result indicates whether the address is
 *      actually contained in the map.
 */
boolean_t
vm_map_lookup_entry(
        vm_map_t                map,
        vm_map_offset_t address,
        vm_map_entry_t          *entry)         /* OUT */
{
        return vm_map_store_lookup_entry( map, address, entry );
}

/*
 *      Routine:        vm_map_find_space
 *      Purpose:
 *              Allocate a range in the specified virtual address map,
 *              returning the entry allocated for that range.
 *              Used by kmem_alloc, etc.
 *
 *              The map must be NOT be locked. It will be returned locked
 *              on KERN_SUCCESS, unlocked on failure.
 *
 *              If an entry is allocated, the object/offset fields
 *              are initialized to zero.
 *
 *      If VM_MAP_FIND_LAST_FREE flag is set, allocate from end of map. This
 *      is currently only used for allocating memory for zones backing
 *      one of the kalloc heaps.(rdar://65832263)
 */
kern_return_t
vm_map_find_space(
        vm_map_t                map,
        vm_map_offset_t         *address,       /* OUT */
        vm_map_size_t           size,
        vm_map_offset_t         mask,
        int                     flags,
        vm_map_kernel_flags_t   vmk_flags,
        vm_tag_t                tag,
        vm_map_entry_t          *o_entry)       /* OUT */
{
        vm_map_entry_t          entry, new_entry, hole_entry;
        vm_map_offset_t         start;
        vm_map_offset_t         end;

        if (size == 0) {
                *address = 0;
                return KERN_INVALID_ARGUMENT;
        }

        new_entry = vm_map_entry_create(map, FALSE);
        vm_map_lock(map);

        if (flags & VM_MAP_FIND_LAST_FREE) {
                assert(!map->disable_vmentry_reuse);
                /* TODO: Make backward lookup generic and support guard pages */
                assert(!vmk_flags.vmkf_guard_after && !vmk_flags.vmkf_guard_before);
                assert(VM_MAP_PAGE_ALIGNED(size, VM_MAP_PAGE_MASK(map)));

                /* Allocate space from end of map */
                vm_map_store_find_last_free(map, &entry);

                if (!entry) {
                        goto noSpace;
                }

                if (entry == vm_map_to_entry(map)) {
                        end = map->max_offset;
                } else {
                        end = entry->vme_start;
                }

                while (TRUE) {
                        vm_map_entry_t prev;

                        start = end - size;

                        if ((start < map->min_offset) || end < start) {
                                goto noSpace;
                        }

                        prev = entry->vme_prev;
                        entry = prev;

                        if (prev == vm_map_to_entry(map)) {
                                break;
                        }

                        if (prev->vme_end <= start) {
                                break;
                        }

                        /*
                         *      Didn't fit -- move to the next entry.
                         */

                        end = entry->vme_start;
                }
        } else {
                if (vmk_flags.vmkf_guard_after) {
                        /* account for the back guard page in the size */
                        size += VM_MAP_PAGE_SIZE(map);
                }

                /*
                 *      Look for the first possible address; if there's already
                 *      something at this address, we have to start after it.
                 */

                if (map->disable_vmentry_reuse == TRUE) {
                        VM_MAP_HIGHEST_ENTRY(map, entry, start);
                } else {
                        if (map->holelistenabled) {
                                hole_entry = CAST_TO_VM_MAP_ENTRY(map->holes_list);

                                if (hole_entry == NULL) {
                                        /*
                                         * No more space in the map?
                                         */
                                        goto noSpace;
                                }

                                entry = hole_entry;
                                start = entry->vme_start;
                        } else {
                                assert(first_free_is_valid(map));
                                if ((entry = map->first_free) == vm_map_to_entry(map)) {
                                        start = map->min_offset;
                                } else {
                                        start = entry->vme_end;
                                }
                        }
                }

                /*
                 *      In any case, the "entry" always precedes
                 *      the proposed new region throughout the loop:
                 */

                while (TRUE) {
                        vm_map_entry_t  next;

                        /*
                         *      Find the end of the proposed new region.
                         *      Be sure we didn't go beyond the end, or
                         *      wrap around the address.
                         */

                        if (vmk_flags.vmkf_guard_before) {
                                /* reserve space for the front guard page */
                                start += VM_MAP_PAGE_SIZE(map);
                        }
                        end = ((start + mask) & ~mask);

                        if (end < start) {
                                goto noSpace;
                        }
                        start = end;
                        assert(VM_MAP_PAGE_ALIGNED(start, VM_MAP_PAGE_MASK(map)));
                        end += size;
                        assert(VM_MAP_PAGE_ALIGNED(end, VM_MAP_PAGE_MASK(map)));

                        if ((end > map->max_offset) || (end < start)) {
                                goto noSpace;
                        }

                        next = entry->vme_next;

                        if (map->holelistenabled) {
                                if (entry->vme_end >= end) {
                                        break;
                                }
                        } else {
                                /*
                                 *      If there are no more entries, we must win.
                                 *
                                 *      OR
                                 *
                                 *      If there is another entry, it must be
                                 *      after the end of the potential new region.
                                 */

                                if (next == vm_map_to_entry(map)) {
                                        break;
                                }

                                if (next->vme_start >= end) {
                                        break;
                                }
                        }

                        /*
                         *      Didn't fit -- move to the next entry.
                         */

                        entry = next;

                        if (map->holelistenabled) {
                                if (entry == CAST_TO_VM_MAP_ENTRY(map->holes_list)) {
                                        /*
                                         * Wrapped around
                                         */
                                        goto noSpace;
                                }
                                start = entry->vme_start;
                        } else {
                                start = entry->vme_end;
                        }
                }

                if (vmk_flags.vmkf_guard_before) {
                        /* go back for the front guard page */
                        start -= VM_MAP_PAGE_SIZE(map);
                }
        }

        if (map->holelistenabled) {
                if (vm_map_lookup_entry(map, entry->vme_start, &entry)) {
                        panic("Found an existing entry (%p) instead of potential hole at address: 0x%llx.\n", entry, (unsigned long long)entry->vme_start);
                }
        }

        /*
         *      At this point,
         *              "start" and "end" should define the endpoints of the
         *                      available new range, and
         *              "entry" should refer to the region before the new
         *                      range, and
         *
         *              the map should be locked.
         */

        *address = start;

        assert(start < end);
        new_entry->vme_start = start;
        new_entry->vme_end = end;
        assert(page_aligned(new_entry->vme_start));
        assert(page_aligned(new_entry->vme_end));
        assert(VM_MAP_PAGE_ALIGNED(new_entry->vme_start,
            VM_MAP_PAGE_MASK(map)));
        assert(VM_MAP_PAGE_ALIGNED(new_entry->vme_end,
            VM_MAP_PAGE_MASK(map)));

        new_entry->is_shared = FALSE;
        new_entry->is_sub_map = FALSE;
        new_entry->use_pmap = TRUE;
        VME_OBJECT_SET(new_entry, VM_OBJECT_NULL);
        VME_OFFSET_SET(new_entry, (vm_object_offset_t) 0);

        new_entry->needs_copy = FALSE;

        new_entry->inheritance = VM_INHERIT_DEFAULT;
        new_entry->protection = VM_PROT_DEFAULT;
        new_entry->max_protection = VM_PROT_ALL;
        new_entry->behavior = VM_BEHAVIOR_DEFAULT;
        new_entry->wired_count = 0;
        new_entry->user_wired_count = 0;

        new_entry->in_transition = FALSE;
        new_entry->needs_wakeup = FALSE;
        new_entry->no_cache = FALSE;
        new_entry->permanent = FALSE;
        new_entry->superpage_size = FALSE;
        if (VM_MAP_PAGE_SHIFT(map) != PAGE_SHIFT) {
                new_entry->map_aligned = TRUE;
        } else {
                new_entry->map_aligned = FALSE;
        }

        new_entry->used_for_jit = FALSE;
        new_entry->pmap_cs_associated = FALSE;
        new_entry->zero_wired_pages = FALSE;
        new_entry->iokit_acct = FALSE;
        new_entry->vme_resilient_codesign = FALSE;
        new_entry->vme_resilient_media = FALSE;
        if (vmk_flags.vmkf_atomic_entry) {
                new_entry->vme_atomic = TRUE;
        } else {
                new_entry->vme_atomic = FALSE;
        }

        VME_ALIAS_SET(new_entry, tag);

        /*
         *      Insert the new entry into the list
         */

        vm_map_store_entry_link(map, entry, new_entry, VM_MAP_KERNEL_FLAGS_NONE);

        map->size += size;

        /*
         *      Update the lookup hint
         */
        SAVE_HINT_MAP_WRITE(map, new_entry);

        *o_entry = new_entry;
        return KERN_SUCCESS;

noSpace:

        vm_map_entry_dispose(map, new_entry);
        vm_map_unlock(map);
        return KERN_NO_SPACE;
}

int vm_map_pmap_enter_print = FALSE;
int vm_map_pmap_enter_enable = FALSE;

/*
 *      Routine:        vm_map_pmap_enter [internal only]
 *
 *      Description:
 *              Force pages from the specified object to be entered into
 *              the pmap at the specified address if they are present.
 *              As soon as a page not found in the object the scan ends.
 *
 *      Returns:
 *              Nothing.
 *
 *      In/out conditions:
 *              The source map should not be locked on entry.
 */
__unused static void
vm_map_pmap_enter(
        vm_map_t                map,
        vm_map_offset_t         addr,
        vm_map_offset_t         end_addr,
        vm_object_t             object,
        vm_object_offset_t      offset,
        vm_prot_t               protection)
{
        int                     type_of_fault;
        kern_return_t           kr;
        struct vm_object_fault_info fault_info = {};

        if (map->pmap == 0) {
                return;
        }

        assert(VM_MAP_PAGE_SHIFT(map) == PAGE_SHIFT);

        while (addr < end_addr) {
                vm_page_t       m;


                /*
                 * TODO:
                 * From vm_map_enter(), we come into this function without the map
                 * lock held or the object lock held.
                 * We haven't taken a reference on the object either.
                 * We should do a proper lookup on the map to make sure
                 * that things are sane before we go locking objects that
                 * could have been deallocated from under us.
                 */

                vm_object_lock(object);

                m = vm_page_lookup(object, offset);

                if (m == VM_PAGE_NULL || m->vmp_busy || m->vmp_fictitious ||
                    (m->vmp_unusual && (m->vmp_error || m->vmp_restart || m->vmp_absent))) {
                        vm_object_unlock(object);
                        return;
                }

                if (vm_map_pmap_enter_print) {
                        printf("vm_map_pmap_enter:");
                        printf("map: %p, addr: %llx, object: %p, offset: %llx\n",
                            map, (unsigned long long)addr, object, (unsigned long long)offset);
                }
                type_of_fault = DBG_CACHE_HIT_FAULT;
                kr = vm_fault_enter(m, map->pmap,
                    addr,
                    PAGE_SIZE, 0,
                    protection, protection,
                    VM_PAGE_WIRED(m),
                    FALSE,                 /* change_wiring */
                    VM_KERN_MEMORY_NONE,                 /* tag - not wiring */
                    &fault_info,
                    NULL,                  /* need_retry */
                    &type_of_fault);

                vm_object_unlock(object);

                offset += PAGE_SIZE_64;
                addr += PAGE_SIZE;
        }
}

boolean_t vm_map_pmap_is_empty(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end);
boolean_t
vm_map_pmap_is_empty(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end)
{
#ifdef MACHINE_PMAP_IS_EMPTY
        return pmap_is_empty(map->pmap, start, end);
#else   /* MACHINE_PMAP_IS_EMPTY */
        vm_map_offset_t offset;
        ppnum_t         phys_page;

        if (map->pmap == NULL) {
                return TRUE;
        }

        for (offset = start;
            offset < end;
            offset += PAGE_SIZE) {
                phys_page = pmap_find_phys(map->pmap, offset);
                if (phys_page) {
                        kprintf("vm_map_pmap_is_empty(%p,0x%llx,0x%llx): "
                            "page %d at 0x%llx\n",
                            map, (long long)start, (long long)end,
                            phys_page, (long long)offset);
                        return FALSE;
                }
        }
        return TRUE;
#endif  /* MACHINE_PMAP_IS_EMPTY */
}

#define MAX_TRIES_TO_GET_RANDOM_ADDRESS 1000
kern_return_t
vm_map_random_address_for_size(
        vm_map_t        map,
        vm_map_offset_t *address,
        vm_map_size_t   size)
{
        kern_return_t   kr = KERN_SUCCESS;
        int             tries = 0;
        vm_map_offset_t random_addr = 0;
        vm_map_offset_t hole_end;

        vm_map_entry_t  next_entry = VM_MAP_ENTRY_NULL;
        vm_map_entry_t  prev_entry = VM_MAP_ENTRY_NULL;
        vm_map_size_t   vm_hole_size = 0;
        vm_map_size_t   addr_space_size;

        addr_space_size = vm_map_max(map) - vm_map_min(map);

        assert(VM_MAP_PAGE_ALIGNED(size, VM_MAP_PAGE_MASK(map)));

        while (tries < MAX_TRIES_TO_GET_RANDOM_ADDRESS) {
                random_addr = ((vm_map_offset_t)random()) << VM_MAP_PAGE_SHIFT(map);
                random_addr = vm_map_trunc_page(
                        vm_map_min(map) + (random_addr % addr_space_size),
                        VM_MAP_PAGE_MASK(map));

                if (vm_map_lookup_entry(map, random_addr, &prev_entry) == FALSE) {
                        if (prev_entry == vm_map_to_entry(map)) {
                                next_entry = vm_map_first_entry(map);
                        } else {
                                next_entry = prev_entry->vme_next;
                        }
                        if (next_entry == vm_map_to_entry(map)) {
                                hole_end = vm_map_max(map);
                        } else {
                                hole_end = next_entry->vme_start;
                        }
                        vm_hole_size = hole_end - random_addr;
                        if (vm_hole_size >= size) {
                                *address = random_addr;
                                break;
                        }
                }
                tries++;
        }

        if (tries == MAX_TRIES_TO_GET_RANDOM_ADDRESS) {
                kr = KERN_NO_SPACE;
        }
        return kr;
}

static boolean_t
vm_memory_malloc_no_cow(
        int alias)
{
        uint64_t alias_mask;

        if (alias > 63) {
                return FALSE;
        }

        alias_mask = 1ULL << alias;
        if (alias_mask & vm_memory_malloc_no_cow_mask) {
                return TRUE;
        }
        return FALSE;
}

/*
 *      Routine:        vm_map_enter
 *
 *      Description:
 *              Allocate a range in the specified virtual address map.
 *              The resulting range will refer to memory defined by
 *              the given memory object and offset into that object.
 *
 *              Arguments are as defined in the vm_map call.
 */
static unsigned int vm_map_enter_restore_successes = 0;
static unsigned int vm_map_enter_restore_failures = 0;
kern_return_t
vm_map_enter(
        vm_map_t                map,
        vm_map_offset_t         *address,       /* IN/OUT */
        vm_map_size_t           size,
        vm_map_offset_t         mask,
        int                     flags,
        vm_map_kernel_flags_t   vmk_flags,
        vm_tag_t                alias,
        vm_object_t             object,
        vm_object_offset_t      offset,
        boolean_t               needs_copy,
        vm_prot_t               cur_protection,
        vm_prot_t               max_protection,
        vm_inherit_t            inheritance)
{
        vm_map_entry_t          entry, new_entry;
        vm_map_offset_t         start, tmp_start, tmp_offset;
        vm_map_offset_t         end, tmp_end;
        vm_map_offset_t         tmp2_start, tmp2_end;
        vm_map_offset_t         desired_empty_end;
        vm_map_offset_t         step;
        kern_return_t           result = KERN_SUCCESS;
        vm_map_t                zap_old_map = VM_MAP_NULL;
        vm_map_t                zap_new_map = VM_MAP_NULL;
        boolean_t               map_locked = FALSE;
        boolean_t               pmap_empty = TRUE;
        boolean_t               new_mapping_established = FALSE;
        boolean_t               keep_map_locked = vmk_flags.vmkf_keep_map_locked;
        boolean_t               anywhere = ((flags & VM_FLAGS_ANYWHERE) != 0);
        boolean_t               purgable = ((flags & VM_FLAGS_PURGABLE) != 0);
        boolean_t               overwrite = ((flags & VM_FLAGS_OVERWRITE) != 0);
        boolean_t               no_cache = ((flags & VM_FLAGS_NO_CACHE) != 0);
        boolean_t               is_submap = vmk_flags.vmkf_submap;
        boolean_t               permanent = vmk_flags.vmkf_permanent;
        boolean_t               no_copy_on_read = vmk_flags.vmkf_no_copy_on_read;
        boolean_t               entry_for_jit = vmk_flags.vmkf_map_jit;
        boolean_t               iokit_acct = vmk_flags.vmkf_iokit_acct;
        boolean_t               translated_allow_execute = vmk_flags.vmkf_translated_allow_execute;
        boolean_t               resilient_codesign = ((flags & VM_FLAGS_RESILIENT_CODESIGN) != 0);
        boolean_t               resilient_media = ((flags & VM_FLAGS_RESILIENT_MEDIA) != 0);
        boolean_t               random_address = ((flags & VM_FLAGS_RANDOM_ADDR) != 0);
        unsigned int            superpage_size = ((flags & VM_FLAGS_SUPERPAGE_MASK) >> VM_FLAGS_SUPERPAGE_SHIFT);
        vm_tag_t                user_alias;
        vm_map_offset_t         effective_min_offset, effective_max_offset;
        kern_return_t           kr;
        boolean_t               clear_map_aligned = FALSE;
        vm_map_entry_t          hole_entry;
        vm_map_size_t           chunk_size = 0;

        assertf(vmk_flags.__vmkf_unused == 0, "vmk_flags unused=0x%x\n", vmk_flags.__vmkf_unused);

        if (flags & VM_FLAGS_4GB_CHUNK) {
#if defined(__LP64__)
                chunk_size = (4ULL * 1024 * 1024 * 1024); /* max. 4GB chunks for the new allocation */
#else /* __LP64__ */
                chunk_size = ANON_CHUNK_SIZE;
#endif /* __LP64__ */
        } else {
                chunk_size = ANON_CHUNK_SIZE;
        }

        if (superpage_size) {
                switch (superpage_size) {
                        /*
                         * Note that the current implementation only supports
                         * a single size for superpages, SUPERPAGE_SIZE, per
                         * architecture. As soon as more sizes are supposed
                         * to be supported, SUPERPAGE_SIZE has to be replaced
                         * with a lookup of the size depending on superpage_size.
                         */
#ifdef __x86_64__
                case SUPERPAGE_SIZE_ANY:
                        /* handle it like 2 MB and round up to page size */
                        size = (size + 2 * 1024 * 1024 - 1) & ~(2 * 1024 * 1024 - 1);
                        OS_FALLTHROUGH;
                case SUPERPAGE_SIZE_2MB:
                        break;
#endif
                default:
                        return KERN_INVALID_ARGUMENT;
                }
                mask = SUPERPAGE_SIZE - 1;
                if (size & (SUPERPAGE_SIZE - 1)) {
                        return KERN_INVALID_ARGUMENT;
                }
                inheritance = VM_INHERIT_NONE;  /* fork() children won't inherit superpages */
        }


        if ((cur_protection & VM_PROT_WRITE) &&
            (cur_protection & VM_PROT_EXECUTE) &&
#if XNU_TARGET_OS_OSX
            map->pmap != kernel_pmap &&
            (cs_process_global_enforcement() ||
            (vmk_flags.vmkf_cs_enforcement_override
            ? vmk_flags.vmkf_cs_enforcement
            : (vm_map_cs_enforcement(map)
#if __arm64__
            || !VM_MAP_IS_EXOTIC(map)
#endif /* __arm64__ */
            ))) &&
#endif /* XNU_TARGET_OS_OSX */
            (VM_MAP_POLICY_WX_FAIL(map) ||
            VM_MAP_POLICY_WX_STRIP_X(map)) &&
            !entry_for_jit) {
                boolean_t vm_protect_wx_fail = VM_MAP_POLICY_WX_FAIL(map);

                DTRACE_VM3(cs_wx,
                    uint64_t, 0,
                    uint64_t, 0,
                    vm_prot_t, cur_protection);
                printf("CODE SIGNING: %d[%s] %s: curprot cannot be write+execute. %s\n",
                    proc_selfpid(),
                    (current_task()->bsd_info
                    ? proc_name_address(current_task()->bsd_info)
                    : "?"),
                    __FUNCTION__,
                    (vm_protect_wx_fail ? "failing" : "turning off execute"));
                cur_protection &= ~VM_PROT_EXECUTE;
                if (vm_protect_wx_fail) {
                        return KERN_PROTECTION_FAILURE;
                }
        }

        /*
         * If the task has requested executable lockdown,
         * deny any new executable mapping.
         */
        if (map->map_disallow_new_exec == TRUE) {
                if (cur_protection & VM_PROT_EXECUTE) {
                        return KERN_PROTECTION_FAILURE;
                }
        }

        if (resilient_codesign) {
                assert(!is_submap);
                int reject_prot = (needs_copy ? VM_PROT_EXECUTE : (VM_PROT_WRITE | VM_PROT_EXECUTE));
                if ((cur_protection | max_protection) & reject_prot) {
                        return KERN_PROTECTION_FAILURE;
                }
        }

        if (resilient_media) {
                assert(!is_submap);
//              assert(!needs_copy);
                if (object != VM_OBJECT_NULL &&
                    !object->internal) {
                        /*
                         * This mapping is directly backed by an external
                         * memory manager (e.g. a vnode pager for a file):
                         * we would not have any safe place to inject
                         * a zero-filled page if an actual page is not
                         * available, without possibly impacting the actual
                         * contents of the mapped object (e.g. the file),
                         * so we can't provide any media resiliency here.
                         */
                        return KERN_INVALID_ARGUMENT;
                }
        }

        if (is_submap) {
                if (purgable) {
                        /* submaps can not be purgeable */
                        return KERN_INVALID_ARGUMENT;
                }
                if (object == VM_OBJECT_NULL) {
                        /* submaps can not be created lazily */
                        return KERN_INVALID_ARGUMENT;
                }
        }
        if (vmk_flags.vmkf_already) {
                /*
                 * VM_FLAGS_ALREADY says that it's OK if the same mapping
                 * is already present.  For it to be meaningul, the requested
                 * mapping has to be at a fixed address (!VM_FLAGS_ANYWHERE) and
                 * we shouldn't try and remove what was mapped there first
                 * (!VM_FLAGS_OVERWRITE).
                 */
                if ((flags & VM_FLAGS_ANYWHERE) ||
                    (flags & VM_FLAGS_OVERWRITE)) {
                        return KERN_INVALID_ARGUMENT;
                }
        }

        effective_min_offset = map->min_offset;

        if (vmk_flags.vmkf_beyond_max) {
                /*
                 * Allow an insertion beyond the map's max offset.
                 */
#if     !defined(__arm__)
                if (vm_map_is_64bit(map)) {
                        effective_max_offset = 0xFFFFFFFFFFFFF000ULL;
                } else
#endif  /* __arm__ */
                effective_max_offset = 0x00000000FFFFF000ULL;
        } else {
#if XNU_TARGET_OS_OSX
                if (__improbable(vmk_flags.vmkf_32bit_map_va)) {
                        effective_max_offset = MIN(map->max_offset, 0x00000000FFFFF000ULL);
                } else {
                        effective_max_offset = map->max_offset;
                }
#else /* XNU_TARGET_OS_OSX */
                effective_max_offset = map->max_offset;
#endif /* XNU_TARGET_OS_OSX */
        }

        if (size == 0 ||
            (offset & MIN(VM_MAP_PAGE_MASK(map), PAGE_MASK_64)) != 0) {
                *address = 0;
                return KERN_INVALID_ARGUMENT;
        }

        if (map->pmap == kernel_pmap) {
                user_alias = VM_KERN_MEMORY_NONE;
        } else {
                user_alias = alias;
        }

        if (user_alias == VM_MEMORY_MALLOC_MEDIUM) {
                chunk_size = MALLOC_MEDIUM_CHUNK_SIZE;
        }

#define RETURN(value)   { result = value; goto BailOut; }

        assertf(VM_MAP_PAGE_ALIGNED(*address, FOURK_PAGE_MASK), "0x%llx", (uint64_t)*address);
        assertf(VM_MAP_PAGE_ALIGNED(size, FOURK_PAGE_MASK), "0x%llx", (uint64_t)size);
        if (VM_MAP_PAGE_MASK(map) >= PAGE_MASK) {
                assertf(page_aligned(*address), "0x%llx", (uint64_t)*address);
                assertf(page_aligned(size), "0x%llx", (uint64_t)size);
        }

        if (VM_MAP_PAGE_MASK(map) >= PAGE_MASK &&
            !VM_MAP_PAGE_ALIGNED(size, VM_MAP_PAGE_MASK(map))) {
                /*
                 * In most cases, the caller rounds the size up to the
                 * map's page size.
                 * If we get a size that is explicitly not map-aligned here,
                 * we'll have to respect the caller's wish and mark the
                 * mapping as "not map-aligned" to avoid tripping the
                 * map alignment checks later.
                 */
                clear_map_aligned = TRUE;
        }
        if (!anywhere &&
            VM_MAP_PAGE_MASK(map) >= PAGE_MASK &&
            !VM_MAP_PAGE_ALIGNED(*address, VM_MAP_PAGE_MASK(map))) {
                /*
                 * We've been asked to map at a fixed address and that
                 * address is not aligned to the map's specific alignment.
                 * The caller should know what it's doing (i.e. most likely
                 * mapping some fragmented copy map, transferring memory from
                 * a VM map with a different alignment), so clear map_aligned
                 * for this new VM map entry and proceed.
                 */
                clear_map_aligned = TRUE;
        }

        /*
         * Only zero-fill objects are allowed to be purgable.
         * LP64todo - limit purgable objects to 32-bits for now
         */
        if (purgable &&
            (offset != 0 ||
            (object != VM_OBJECT_NULL &&
            (object->vo_size != size ||
            object->purgable == VM_PURGABLE_DENY))
            || size > ANON_MAX_SIZE)) { /* LP64todo: remove when dp capable */
                return KERN_INVALID_ARGUMENT;
        }

        if (!anywhere && overwrite) {
                /*
                 * Create a temporary VM map to hold the old mappings in the
                 * affected area while we create the new one.
                 * This avoids releasing the VM map lock in
                 * vm_map_entry_delete() and allows atomicity
                 * when we want to replace some mappings with a new one.
                 * It also allows us to restore the old VM mappings if the
                 * new mapping fails.
                 */
                zap_old_map = vm_map_create(PMAP_NULL,
                    *address,
                    *address + size,
                    map->hdr.entries_pageable);
                vm_map_set_page_shift(zap_old_map, VM_MAP_PAGE_SHIFT(map));
                vm_map_disable_hole_optimization(zap_old_map);
        }

StartAgain:;

        start = *address;

        if (anywhere) {
                vm_map_lock(map);
                map_locked = TRUE;

                if (entry_for_jit) {
                        if (map->jit_entry_exists &&
                            !VM_MAP_POLICY_ALLOW_MULTIPLE_JIT(map)) {
                                result = KERN_INVALID_ARGUMENT;
                                goto BailOut;
                        }
                        if (VM_MAP_POLICY_ALLOW_JIT_RANDOM_ADDRESS(map)) {
                                random_address = TRUE;
                        }
                }

                if (random_address) {
                        /*
                         * Get a random start address.
                         */
                        result = vm_map_random_address_for_size(map, address, size);
                        if (result != KERN_SUCCESS) {
                                goto BailOut;
                        }
                        start = *address;
                }
#if XNU_TARGET_OS_OSX
                else if ((start == 0 || start == vm_map_min(map)) &&
                    !map->disable_vmentry_reuse &&
                    map->vmmap_high_start != 0) {
                        start = map->vmmap_high_start;
                }
#endif /* XNU_TARGET_OS_OSX */


                /*
                 *      Calculate the first possible address.
                 */

                if (start < effective_min_offset) {
                        start = effective_min_offset;
                }
                if (start > effective_max_offset) {
                        RETURN(KERN_NO_SPACE);
                }

                /*
                 *      Look for the first possible address;
                 *      if there's already something at this
                 *      address, we have to start after it.
                 */

                if (map->disable_vmentry_reuse == TRUE) {
                        VM_MAP_HIGHEST_ENTRY(map, entry, start);
                } else {
                        if (map->holelistenabled) {
                                hole_entry = CAST_TO_VM_MAP_ENTRY(map->holes_list);

                                if (hole_entry == NULL) {
                                        /*
                                         * No more space in the map?
                                         */
                                        result = KERN_NO_SPACE;
                                        goto BailOut;
                                } else {
                                        boolean_t found_hole = FALSE;

                                        do {
                                                if (hole_entry->vme_start >= start) {
                                                        start = hole_entry->vme_start;
                                                        found_hole = TRUE;
                                                        break;
                                                }

                                                if (hole_entry->vme_end > start) {
                                                        found_hole = TRUE;
                                                        break;
                                                }
                                                hole_entry = hole_entry->vme_next;
                                        } while (hole_entry != CAST_TO_VM_MAP_ENTRY(map->holes_list));

                                        if (found_hole == FALSE) {
                                                result = KERN_NO_SPACE;
                                                goto BailOut;
                                        }

                                        entry = hole_entry;

                                        if (start == 0) {
                                                start += PAGE_SIZE_64;
                                        }
                                }
                        } else {
                                assert(first_free_is_valid(map));

                                entry = map->first_free;

                                if (entry == vm_map_to_entry(map)) {
                                        entry = NULL;
                                } else {
                                        if (entry->vme_next == vm_map_to_entry(map)) {
                                                /*
                                                 * Hole at the end of the map.
                                                 */
                                                entry = NULL;
                                        } else {
                                                if (start < (entry->vme_next)->vme_start) {
                                                        start = entry->vme_end;
                                                        start = vm_map_round_page(start,
                                                            VM_MAP_PAGE_MASK(map));
                                                } else {
                                                        /*
                                                         * Need to do a lookup.
                                                         */
                                                        entry = NULL;
                                                }
                                        }
                                }

                                if (entry == NULL) {
                                        vm_map_entry_t  tmp_entry;
                                        if (vm_map_lookup_entry(map, start, &tmp_entry)) {
                                                assert(!entry_for_jit);
                                                start = tmp_entry->vme_end;
                                                start = vm_map_round_page(start,
                                                    VM_MAP_PAGE_MASK(map));
                                        }
                                        entry = tmp_entry;
                                }
                        }
                }

                /*
                 *      In any case, the "entry" always precedes
                 *      the proposed new region throughout the
                 *      loop:
                 */

                while (TRUE) {
                        vm_map_entry_t  next;

                        /*
                         *      Find the end of the proposed new region.
                         *      Be sure we didn't go beyond the end, or
                         *      wrap around the address.
                         */

                        end = ((start + mask) & ~mask);
                        end = vm_map_round_page(end,
                            VM_MAP_PAGE_MASK(map));
                        if (end < start) {
                                RETURN(KERN_NO_SPACE);
                        }
                        start = end;
                        assert(VM_MAP_PAGE_ALIGNED(start,
                            VM_MAP_PAGE_MASK(map)));
                        end += size;

                        /* We want an entire page of empty space, but don't increase the allocation size. */
                        desired_empty_end = vm_map_round_page(end, VM_MAP_PAGE_MASK(map));

                        if ((desired_empty_end > effective_max_offset) || (desired_empty_end < start)) {
                                if (map->wait_for_space) {
                                        assert(!keep_map_locked);
                                        if (size <= (effective_max_offset -
                                            effective_min_offset)) {
                                                assert_wait((event_t)map,
                                                    THREAD_ABORTSAFE);
                                                vm_map_unlock(map);
                                                map_locked = FALSE;
                                                thread_block(THREAD_CONTINUE_NULL);
                                                goto StartAgain;
                                        }
                                }
                                RETURN(KERN_NO_SPACE);
                        }

                        next = entry->vme_next;

                        if (map->holelistenabled) {
                                if (entry->vme_end >= desired_empty_end) {
                                        break;
                                }
                        } else {
                                /*
                                 *      If there are no more entries, we must win.
                                 *
                                 *      OR
                                 *
                                 *      If there is another entry, it must be
                                 *      after the end of the potential new region.
                                 */

                                if (next == vm_map_to_entry(map)) {
                                        break;
                                }

                                if (next->vme_start >= desired_empty_end) {
                                        break;
                                }
                        }

                        /*
                         *      Didn't fit -- move to the next entry.
                         */

                        entry = next;

                        if (map->holelistenabled) {
                                if (entry == CAST_TO_VM_MAP_ENTRY(map->holes_list)) {
                                        /*
                                         * Wrapped around
                                         */
                                        result = KERN_NO_SPACE;
                                        goto BailOut;
                                }
                                start = entry->vme_start;
                        } else {
                                start = entry->vme_end;
                        }

                        start = vm_map_round_page(start,
                            VM_MAP_PAGE_MASK(map));
                }

                if (map->holelistenabled) {
                        if (vm_map_lookup_entry(map, entry->vme_start, &entry)) {
                                panic("Found an existing entry (%p) instead of potential hole at address: 0x%llx.\n", entry, (unsigned long long)entry->vme_start);
                        }
                }

                *address = start;
                assert(VM_MAP_PAGE_ALIGNED(*address,
                    VM_MAP_PAGE_MASK(map)));
        } else {
                if (VM_MAP_PAGE_SHIFT(map) < PAGE_SHIFT &&
                    !overwrite &&
                    user_alias == VM_MEMORY_REALLOC) {
                        /*
                         * Force realloc() to switch to a new allocation,
                         * to prevent 4k-fragmented virtual ranges.
                         */
//                      DEBUG4K_ERROR("no realloc in place");
                        return KERN_NO_SPACE;
                }

                /*
                 *      Verify that:
                 *              the address doesn't itself violate
                 *              the mask requirement.
                 */

                vm_map_lock(map);
                map_locked = TRUE;
                if ((start & mask) != 0) {
                        RETURN(KERN_NO_SPACE);
                }

                /*
                 *      ...     the address is within bounds
                 */

                end = start + size;

                if ((start < effective_min_offset) ||
                    (end > effective_max_offset) ||
                    (start >= end)) {
                        RETURN(KERN_INVALID_ADDRESS);
                }

                if (overwrite && zap_old_map != VM_MAP_NULL) {
                        int remove_flags;
                        /*
                         * Fixed mapping and "overwrite" flag: attempt to
                         * remove all existing mappings in the specified
                         * address range, saving them in our "zap_old_map".
                         */
                        remove_flags = VM_MAP_REMOVE_SAVE_ENTRIES;
                        remove_flags |= VM_MAP_REMOVE_NO_MAP_ALIGN;
                        if (vmk_flags.vmkf_overwrite_immutable) {
                                /* we can overwrite immutable mappings */
                                remove_flags |= VM_MAP_REMOVE_IMMUTABLE;
                        }
                        (void) vm_map_delete(map, start, end,
                            remove_flags,
                            zap_old_map);
                }

                /*
                 *      ...     the starting address isn't allocated
                 */

                if (vm_map_lookup_entry(map, start, &entry)) {
                        if (!(vmk_flags.vmkf_already)) {
                                RETURN(KERN_NO_SPACE);
                        }
                        /*
                         * Check if what's already there is what we want.
                         */
                        tmp_start = start;
                        tmp_offset = offset;
                        if (entry->vme_start < start) {
                                tmp_start -= start - entry->vme_start;
                                tmp_offset -= start - entry->vme_start;
                        }
                        for (; entry->vme_start < end;
                            entry = entry->vme_next) {
                                /*
                                 * Check if the mapping's attributes
                                 * match the existing map entry.
                                 */
                                if (entry == vm_map_to_entry(map) ||
                                    entry->vme_start != tmp_start ||
                                    entry->is_sub_map != is_submap ||
                                    VME_OFFSET(entry) != tmp_offset ||
                                    entry->needs_copy != needs_copy ||
                                    entry->protection != cur_protection ||
                                    entry->max_protection != max_protection ||
                                    entry->inheritance != inheritance ||
                                    entry->iokit_acct != iokit_acct ||
                                    VME_ALIAS(entry) != alias) {
                                        /* not the same mapping ! */
                                        RETURN(KERN_NO_SPACE);
                                }
                                /*
                                 * Check if the same object is being mapped.
                                 */
                                if (is_submap) {
                                        if (VME_SUBMAP(entry) !=
                                            (vm_map_t) object) {
                                                /* not the same submap */
                                                RETURN(KERN_NO_SPACE);
                                        }
                                } else {
                                        if (VME_OBJECT(entry) != object) {
                                                /* not the same VM object... */
                                                vm_object_t obj2;

                                                obj2 = VME_OBJECT(entry);
                                                if ((obj2 == VM_OBJECT_NULL ||
                                                    obj2->internal) &&
                                                    (object == VM_OBJECT_NULL ||
                                                    object->internal)) {
                                                        /*
                                                         * ... but both are
                                                         * anonymous memory,
                                                         * so equivalent.
                                                         */
                                                } else {
                                                        RETURN(KERN_NO_SPACE);
                                                }
                                        }
                                }

                                tmp_offset += entry->vme_end - entry->vme_start;
                                tmp_start += entry->vme_end - entry->vme_start;
                                if (entry->vme_end >= end) {
                                        /* reached the end of our mapping */
                                        break;
                                }
                        }
                        /* it all matches:  let's use what's already there ! */
                        RETURN(KERN_MEMORY_PRESENT);
                }

                /*
                 *      ...     the next region doesn't overlap the
                 *              end point.
                 */

                if ((entry->vme_next != vm_map_to_entry(map)) &&
                    (entry->vme_next->vme_start < end)) {
                        RETURN(KERN_NO_SPACE);
                }
        }

        /*
         *      At this point,
         *              "start" and "end" should define the endpoints of the
         *                      available new range, and
         *              "entry" should refer to the region before the new
         *                      range, and
         *
         *              the map should be locked.
         */

        /*
         *      See whether we can avoid creating a new entry (and object) by
         *      extending one of our neighbors.  [So far, we only attempt to
         *      extend from below.]  Note that we can never extend/join
         *      purgable objects because they need to remain distinct
         *      entities in order to implement their "volatile object"
         *      semantics.
         */

        if (purgable ||
            entry_for_jit ||
            vm_memory_malloc_no_cow(user_alias)) {
                if (object == VM_OBJECT_NULL) {
                        object = vm_object_allocate(size);
                        object->copy_strategy = MEMORY_OBJECT_COPY_NONE;
                        object->true_share = FALSE;
                        if (purgable) {
                                task_t owner;
                                object->purgable = VM_PURGABLE_NONVOLATILE;
                                if (map->pmap == kernel_pmap) {
                                        /*
                                         * Purgeable mappings made in a kernel
                                         * map are "owned" by the kernel itself
                                         * rather than the current user task
                                         * because they're likely to be used by
                                         * more than this user task (see
                                         * execargs_purgeable_allocate(), for
                                         * example).
                                         */
                                        owner = kernel_task;
                                } else {
                                        owner = current_task();
                                }
                                assert(object->vo_owner == NULL);
                                assert(object->resident_page_count == 0);
                                assert(object->wired_page_count == 0);
                                vm_object_lock(object);
                                vm_purgeable_nonvolatile_enqueue(object, owner);
                                vm_object_unlock(object);
                        }
                        offset = (vm_object_offset_t)0;
                }
        } else if (VM_MAP_PAGE_SHIFT(map) < PAGE_SHIFT) {
                /* no coalescing if address space uses sub-pages */
        } else if ((is_submap == FALSE) &&
            (object == VM_OBJECT_NULL) &&
            (entry != vm_map_to_entry(map)) &&
            (entry->vme_end == start) &&
            (!entry->is_shared) &&
            (!entry->is_sub_map) &&
            (!entry->in_transition) &&
            (!entry->needs_wakeup) &&
            (entry->behavior == VM_BEHAVIOR_DEFAULT) &&
            (entry->protection == cur_protection) &&
            (entry->max_protection == max_protection) &&
            (entry->inheritance == inheritance) &&
            ((user_alias == VM_MEMORY_REALLOC) ||
            (VME_ALIAS(entry) == alias)) &&
            (entry->no_cache == no_cache) &&
            (entry->permanent == permanent) &&
            /* no coalescing for immutable executable mappings */
            !((entry->protection & VM_PROT_EXECUTE) &&
            entry->permanent) &&
            (!entry->superpage_size && !superpage_size) &&
            /*
             * No coalescing if not map-aligned, to avoid propagating
             * that condition any further than needed:
             */
            (!entry->map_aligned || !clear_map_aligned) &&
            (!entry->zero_wired_pages) &&
            (!entry->used_for_jit && !entry_for_jit) &&
            (!entry->pmap_cs_associated) &&
            (entry->iokit_acct == iokit_acct) &&
            (!entry->vme_resilient_codesign) &&
            (!entry->vme_resilient_media) &&
            (!entry->vme_atomic) &&
            (entry->vme_no_copy_on_read == no_copy_on_read) &&

            ((entry->vme_end - entry->vme_start) + size <=
            (user_alias == VM_MEMORY_REALLOC ?
            ANON_CHUNK_SIZE :
            NO_COALESCE_LIMIT)) &&

            (entry->wired_count == 0)) {        /* implies user_wired_count == 0 */
                if (vm_object_coalesce(VME_OBJECT(entry),
                    VM_OBJECT_NULL,
                    VME_OFFSET(entry),
                    (vm_object_offset_t) 0,
                    (vm_map_size_t)(entry->vme_end - entry->vme_start),
                    (vm_map_size_t)(end - entry->vme_end))) {
                        /*
                         *      Coalesced the two objects - can extend
                         *      the previous map entry to include the
                         *      new range.
                         */
                        map->size += (end - entry->vme_end);
                        assert(entry->vme_start < end);
                        assert(VM_MAP_PAGE_ALIGNED(end,
                            VM_MAP_PAGE_MASK(map)));
                        if (__improbable(vm_debug_events)) {
                                DTRACE_VM5(map_entry_extend, vm_map_t, map, vm_map_entry_t, entry, vm_address_t, entry->vme_start, vm_address_t, entry->vme_end, vm_address_t, end);
                        }
                        entry->vme_end = end;
                        if (map->holelistenabled) {
                                vm_map_store_update_first_free(map, entry, TRUE);
                        } else {
                                vm_map_store_update_first_free(map, map->first_free, TRUE);
                        }
                        new_mapping_established = TRUE;
                        RETURN(KERN_SUCCESS);
                }
        }

        step = superpage_size ? SUPERPAGE_SIZE : (end - start);
        new_entry = NULL;

        for (tmp2_start = start; tmp2_start < end; tmp2_start += step) {
                tmp2_end = tmp2_start + step;
                /*
                 *      Create a new entry
                 *
                 * XXX FBDP
                 * The reserved "page zero" in each process's address space can
                 * be arbitrarily large.  Splitting it into separate objects and
                 * therefore different VM map entries serves no purpose and just
                 * slows down operations on the VM map, so let's not split the
                 * allocation into chunks if the max protection is NONE.  That
                 * memory should never be accessible, so it will never get to the
                 * default pager.
                 */
                tmp_start = tmp2_start;
                if (object == VM_OBJECT_NULL &&
                    size > chunk_size &&
                    max_protection != VM_PROT_NONE &&
                    superpage_size == 0) {
                        tmp_end = tmp_start + chunk_size;
                } else {
                        tmp_end = tmp2_end;
                }
                do {
                        new_entry = vm_map_entry_insert(map,
                            entry, tmp_start, tmp_end,
                            object, offset, needs_copy,
                            FALSE, FALSE,
                            cur_protection, max_protection,
                            VM_BEHAVIOR_DEFAULT,
                            (entry_for_jit && !VM_MAP_POLICY_ALLOW_JIT_INHERIT(map) ?
                            VM_INHERIT_NONE : inheritance),
                            0,
                            no_cache,
                            permanent,
                            no_copy_on_read,
                            superpage_size,
                            clear_map_aligned,
                            is_submap,
                            entry_for_jit,
                            alias,
                            translated_allow_execute);

                        assert((object != kernel_object) || (VM_KERN_MEMORY_NONE != alias));

                        if (resilient_codesign) {
                                int reject_prot = (needs_copy ? VM_PROT_EXECUTE : (VM_PROT_WRITE | VM_PROT_EXECUTE));
                                if (!((cur_protection | max_protection) & reject_prot)) {
                                        new_entry->vme_resilient_codesign = TRUE;
                                }
                        }

                        if (resilient_media &&
                            (object == VM_OBJECT_NULL ||
                            object->internal)) {
                                new_entry->vme_resilient_media = TRUE;
                        }

                        assert(!new_entry->iokit_acct);
                        if (!is_submap &&
                            object != VM_OBJECT_NULL &&
                            (object->purgable != VM_PURGABLE_DENY ||
                            object->vo_ledger_tag)) {
                                assert(new_entry->use_pmap);
                                assert(!new_entry->iokit_acct);
                                /*
                                 * Turn off pmap accounting since
                                 * purgeable (or tagged) objects have their
                                 * own ledgers.
                                 */
                                new_entry->use_pmap = FALSE;
                        } else if (!is_submap &&
                            iokit_acct &&
                            object != VM_OBJECT_NULL &&
                            object->internal) {
                                /* alternate accounting */
                                assert(!new_entry->iokit_acct);
                                assert(new_entry->use_pmap);
                                new_entry->iokit_acct = TRUE;
                                new_entry->use_pmap = FALSE;
                                DTRACE_VM4(
                                        vm_map_iokit_mapped_region,
                                        vm_map_t, map,
                                        vm_map_offset_t, new_entry->vme_start,
                                        vm_map_offset_t, new_entry->vme_end,
                                        int, VME_ALIAS(new_entry));
                                vm_map_iokit_mapped_region(
                                        map,
                                        (new_entry->vme_end -
                                        new_entry->vme_start));
                        } else if (!is_submap) {
                                assert(!new_entry->iokit_acct);
                                assert(new_entry->use_pmap);
                        }

                        if (is_submap) {
                                vm_map_t        submap;
                                boolean_t       submap_is_64bit;
                                boolean_t       use_pmap;

                                assert(new_entry->is_sub_map);
                                assert(!new_entry->use_pmap);
                                assert(!new_entry->iokit_acct);
                                submap = (vm_map_t) object;
                                submap_is_64bit = vm_map_is_64bit(submap);
                                use_pmap = vmk_flags.vmkf_nested_pmap;
#ifndef NO_NESTED_PMAP
                                if (use_pmap && submap->pmap == NULL) {
                                        ledger_t ledger = map->pmap->ledger;
                                        /* we need a sub pmap to nest... */
                                        submap->pmap = pmap_create_options(ledger, 0,
                                            submap_is_64bit ? PMAP_CREATE_64BIT : 0);
                                        if (submap->pmap == NULL) {
                                                /* let's proceed without nesting... */
                                        }
#if     defined(__arm__) || defined(__arm64__)
                                        else {
                                                pmap_set_nested(submap->pmap);
                                        }
#endif
                                }
                                if (use_pmap && submap->pmap != NULL) {
                                        if (VM_MAP_PAGE_SHIFT(map) != VM_MAP_PAGE_SHIFT(submap)) {
                                                DEBUG4K_ERROR("map %p (%d) submap %p (%d): incompatible page sizes\n", map, VM_MAP_PAGE_SHIFT(map), submap, VM_MAP_PAGE_SHIFT(submap));
                                                kr = KERN_FAILURE;
                                        } else {
                                                kr = pmap_nest(map->pmap,
                                                    submap->pmap,
                                                    tmp_start,
                                                    tmp_end - tmp_start);
                                        }
                                        if (kr != KERN_SUCCESS) {
                                                printf("vm_map_enter: "
                                                    "pmap_nest(0x%llx,0x%llx) "
                                                    "error 0x%x\n",
                                                    (long long)tmp_start,
                                                    (long long)tmp_end,
                                                    kr);
                                        } else {
                                                /* we're now nested ! */
                                                new_entry->use_pmap = TRUE;
                                                pmap_empty = FALSE;
                                        }
                                }
#endif /* NO_NESTED_PMAP */
                        }
                        entry = new_entry;

                        if (superpage_size) {
                                vm_page_t pages, m;
                                vm_object_t sp_object;
                                vm_object_offset_t sp_offset;

                                VME_OFFSET_SET(entry, 0);

                                /* allocate one superpage */
                                kr = cpm_allocate(SUPERPAGE_SIZE, &pages, 0, SUPERPAGE_NBASEPAGES - 1, TRUE, 0);
                                if (kr != KERN_SUCCESS) {
                                        /* deallocate whole range... */
                                        new_mapping_established = TRUE;
                                        /* ... but only up to "tmp_end" */
                                        size -= end - tmp_end;
                                        RETURN(kr);
                                }

                                /* create one vm_object per superpage */
                                sp_object = vm_object_allocate((vm_map_size_t)(entry->vme_end - entry->vme_start));
                                sp_object->phys_contiguous = TRUE;
                                sp_object->vo_shadow_offset = (vm_object_offset_t)VM_PAGE_GET_PHYS_PAGE(pages) * PAGE_SIZE;
                                VME_OBJECT_SET(entry, sp_object);
                                assert(entry->use_pmap);

                                /* enter the base pages into the object */
                                vm_object_lock(sp_object);
                                for (sp_offset = 0;
                                    sp_offset < SUPERPAGE_SIZE;
                                    sp_offset += PAGE_SIZE) {
                                        m = pages;
                                        pmap_zero_page(VM_PAGE_GET_PHYS_PAGE(m));
                                        pages = NEXT_PAGE(m);
                                        *(NEXT_PAGE_PTR(m)) = VM_PAGE_NULL;
                                        vm_page_insert_wired(m, sp_object, sp_offset, VM_KERN_MEMORY_OSFMK);
                                }
                                vm_object_unlock(sp_object);
                        }
                } while (tmp_end != tmp2_end &&
                    (tmp_start = tmp_end) &&
                    (tmp_end = (tmp2_end - tmp_end > chunk_size) ?
                    tmp_end + chunk_size : tmp2_end));
        }

        new_mapping_established = TRUE;

BailOut:
        assert(map_locked == TRUE);

        if (result == KERN_SUCCESS) {
                vm_prot_t pager_prot;
                memory_object_t pager;

#if DEBUG
                if (pmap_empty &&
                    !(vmk_flags.vmkf_no_pmap_check)) {
                        assert(vm_map_pmap_is_empty(map,
                            *address,
                            *address + size));
                }
#endif /* DEBUG */

                /*
                 * For "named" VM objects, let the pager know that the
                 * memory object is being mapped.  Some pagers need to keep
                 * track of this, to know when they can reclaim the memory
                 * object, for example.
                 * VM calls memory_object_map() for each mapping (specifying
                 * the protection of each mapping) and calls
                 * memory_object_last_unmap() when all the mappings are gone.
                 */
                pager_prot = max_protection;
                if (needs_copy) {
                        /*
                         * Copy-On-Write mapping: won't modify
                         * the memory object.
                         */
                        pager_prot &= ~VM_PROT_WRITE;
                }
                if (!is_submap &&
                    object != VM_OBJECT_NULL &&
                    object->named &&
                    object->pager != MEMORY_OBJECT_NULL) {
                        vm_object_lock(object);
                        pager = object->pager;
                        if (object->named &&
                            pager != MEMORY_OBJECT_NULL) {
                                assert(object->pager_ready);
                                vm_object_mapping_wait(object, THREAD_UNINT);
                                vm_object_mapping_begin(object);
                                vm_object_unlock(object);

                                kr = memory_object_map(pager, pager_prot);
                                assert(kr == KERN_SUCCESS);

                                vm_object_lock(object);
                                vm_object_mapping_end(object);
                        }
                        vm_object_unlock(object);
                }
        }

        assert(map_locked == TRUE);

        if (!keep_map_locked) {
                vm_map_unlock(map);
                map_locked = FALSE;
        }

        /*
         * We can't hold the map lock if we enter this block.
         */

        if (result == KERN_SUCCESS) {
                /*      Wire down the new entry if the user
                 *      requested all new map entries be wired.
                 */
                if ((map->wiring_required) || (superpage_size)) {
                        assert(!keep_map_locked);
                        pmap_empty = FALSE; /* pmap won't be empty */
                        kr = vm_map_wire_kernel(map, start, end,
                            new_entry->protection, VM_KERN_MEMORY_MLOCK,
                            TRUE);
                        result = kr;
                }

        }

        if (result != KERN_SUCCESS) {
                if (new_mapping_established) {
                        /*
                         * We have to get rid of the new mappings since we
                         * won't make them available to the user.
                         * Try and do that atomically, to minimize the risk
                         * that someone else create new mappings that range.
                         */
                        zap_new_map = vm_map_create(PMAP_NULL,
                            *address,
                            *address + size,
                            map->hdr.entries_pageable);
                        vm_map_set_page_shift(zap_new_map,
                            VM_MAP_PAGE_SHIFT(map));
                        vm_map_disable_hole_optimization(zap_new_map);

                        if (!map_locked) {
                                vm_map_lock(map);
                                map_locked = TRUE;
                        }
                        (void) vm_map_delete(map, *address, *address + size,
                            (VM_MAP_REMOVE_SAVE_ENTRIES |
                            VM_MAP_REMOVE_NO_MAP_ALIGN),
                            zap_new_map);
                }
                if (zap_old_map != VM_MAP_NULL &&
                    zap_old_map->hdr.nentries != 0) {
                        vm_map_entry_t  entry1, entry2;

                        /*
                         * The new mapping failed.  Attempt to restore
                         * the old mappings, saved in the "zap_old_map".
                         */
                        if (!map_locked) {
                                vm_map_lock(map);
                                map_locked = TRUE;
                        }

                        /* first check if the coast is still clear */
                        start = vm_map_first_entry(zap_old_map)->vme_start;
                        end = vm_map_last_entry(zap_old_map)->vme_end;
                        if (vm_map_lookup_entry(map, start, &entry1) ||
                            vm_map_lookup_entry(map, end, &entry2) ||
                            entry1 != entry2) {
                                /*
                                 * Part of that range has already been
                                 * re-mapped:  we can't restore the old
                                 * mappings...
                                 */
                                vm_map_enter_restore_failures++;
                        } else {
                                /*
                                 * Transfer the saved map entries from
                                 * "zap_old_map" to the original "map",
                                 * inserting them all after "entry1".
                                 */
                                for (entry2 = vm_map_first_entry(zap_old_map);
                                    entry2 != vm_map_to_entry(zap_old_map);
                                    entry2 = vm_map_first_entry(zap_old_map)) {
                                        vm_map_size_t entry_size;

                                        entry_size = (entry2->vme_end -
                                            entry2->vme_start);
                                        vm_map_store_entry_unlink(zap_old_map,
                                            entry2);
                                        zap_old_map->size -= entry_size;
                                        vm_map_store_entry_link(map, entry1, entry2,
                                            VM_MAP_KERNEL_FLAGS_NONE);
                                        map->size += entry_size;
                                        entry1 = entry2;
                                }
                                if (map->wiring_required) {
                                        /*
                                         * XXX TODO: we should rewire the
                                         * old pages here...
                                         */
                                }
                                vm_map_enter_restore_successes++;
                        }
                }
        }

        /*
         * The caller is responsible for releasing the lock if it requested to
         * keep the map locked.
         */
        if (map_locked && !keep_map_locked) {
                vm_map_unlock(map);
        }

        /*
         * Get rid of the "zap_maps" and all the map entries that
         * they may still contain.
         */
        if (zap_old_map != VM_MAP_NULL) {
                vm_map_destroy(zap_old_map, VM_MAP_REMOVE_NO_PMAP_CLEANUP);
                zap_old_map = VM_MAP_NULL;
        }
        if (zap_new_map != VM_MAP_NULL) {
                vm_map_destroy(zap_new_map, VM_MAP_REMOVE_NO_PMAP_CLEANUP);
                zap_new_map = VM_MAP_NULL;
        }

        return result;

#undef  RETURN
}

#if __arm64__
extern const struct memory_object_pager_ops fourk_pager_ops;
kern_return_t
vm_map_enter_fourk(
        vm_map_t                map,
        vm_map_offset_t         *address,       /* IN/OUT */
        vm_map_size_t           size,
        vm_map_offset_t         mask,
        int                     flags,
        vm_map_kernel_flags_t   vmk_flags,
        vm_tag_t                alias,
        vm_object_t             object,
        vm_object_offset_t      offset,
        boolean_t               needs_copy,
        vm_prot_t               cur_protection,
        vm_prot_t               max_protection,
        vm_inherit_t            inheritance)
{
        vm_map_entry_t          entry, new_entry;
        vm_map_offset_t         start, fourk_start;
        vm_map_offset_t         end, fourk_end;
        vm_map_size_t           fourk_size;
        kern_return_t           result = KERN_SUCCESS;
        vm_map_t                zap_old_map = VM_MAP_NULL;
        vm_map_t                zap_new_map = VM_MAP_NULL;
        boolean_t               map_locked = FALSE;
        boolean_t               pmap_empty = TRUE;
        boolean_t               new_mapping_established = FALSE;
        boolean_t               keep_map_locked = vmk_flags.vmkf_keep_map_locked;
        boolean_t               anywhere = ((flags & VM_FLAGS_ANYWHERE) != 0);
        boolean_t               purgable = ((flags & VM_FLAGS_PURGABLE) != 0);
        boolean_t               overwrite = ((flags & VM_FLAGS_OVERWRITE) != 0);
        boolean_t               no_cache = ((flags & VM_FLAGS_NO_CACHE) != 0);
        boolean_t               is_submap = vmk_flags.vmkf_submap;
        boolean_t               permanent = vmk_flags.vmkf_permanent;
        boolean_t               no_copy_on_read = vmk_flags.vmkf_permanent;
        boolean_t               entry_for_jit = vmk_flags.vmkf_map_jit;
//      boolean_t               iokit_acct = vmk_flags.vmkf_iokit_acct;
        boolean_t               translated_allow_execute = vmk_flags.vmkf_translated_allow_execute;
        unsigned int            superpage_size = ((flags & VM_FLAGS_SUPERPAGE_MASK) >> VM_FLAGS_SUPERPAGE_SHIFT);
        vm_map_offset_t         effective_min_offset, effective_max_offset;
        kern_return_t           kr;
        boolean_t               clear_map_aligned = FALSE;
        memory_object_t         fourk_mem_obj;
        vm_object_t             fourk_object;
        vm_map_offset_t         fourk_pager_offset;
        int                     fourk_pager_index_start, fourk_pager_index_num;
        int                     cur_idx;
        boolean_t               fourk_copy;
        vm_object_t             copy_object;
        vm_object_offset_t      copy_offset;

        if (VM_MAP_PAGE_MASK(map) < PAGE_MASK) {
                panic("%s:%d\n", __FUNCTION__, __LINE__);
        }
        fourk_mem_obj = MEMORY_OBJECT_NULL;
        fourk_object = VM_OBJECT_NULL;

        if (superpage_size) {
                return KERN_NOT_SUPPORTED;
        }

        if ((cur_protection & VM_PROT_WRITE) &&
            (cur_protection & VM_PROT_EXECUTE) &&
#if XNU_TARGET_OS_OSX
            map->pmap != kernel_pmap &&
            (vm_map_cs_enforcement(map)
#if __arm64__
            || !VM_MAP_IS_EXOTIC(map)
#endif /* __arm64__ */
            ) &&
#endif /* XNU_TARGET_OS_OSX */
            !entry_for_jit) {
                DTRACE_VM3(cs_wx,
                    uint64_t, 0,
                    uint64_t, 0,
                    vm_prot_t, cur_protection);
                printf("CODE SIGNING: %d[%s] %s: curprot cannot be write+execute. "
                    "turning off execute\n",
                    proc_selfpid(),
                    (current_task()->bsd_info
                    ? proc_name_address(current_task()->bsd_info)
                    : "?"),
                    __FUNCTION__);
                cur_protection &= ~VM_PROT_EXECUTE;
        }

        /*
         * If the task has requested executable lockdown,
         * deny any new executable mapping.
         */
        if (map->map_disallow_new_exec == TRUE) {
                if (cur_protection & VM_PROT_EXECUTE) {
                        return KERN_PROTECTION_FAILURE;
                }
        }

        if (is_submap) {
                return KERN_NOT_SUPPORTED;
        }
        if (vmk_flags.vmkf_already) {
                return KERN_NOT_SUPPORTED;
        }
        if (purgable || entry_for_jit) {
                return KERN_NOT_SUPPORTED;
        }

        effective_min_offset = map->min_offset;

        if (vmk_flags.vmkf_beyond_max) {
                return KERN_NOT_SUPPORTED;
        } else {
                effective_max_offset = map->max_offset;
        }

        if (size == 0 ||
            (offset & FOURK_PAGE_MASK) != 0) {
                *address = 0;
                return KERN_INVALID_ARGUMENT;
        }

#define RETURN(value)   { result = value; goto BailOut; }

        assert(VM_MAP_PAGE_ALIGNED(*address, FOURK_PAGE_MASK));
        assert(VM_MAP_PAGE_ALIGNED(size, FOURK_PAGE_MASK));

        if (!anywhere && overwrite) {
                return KERN_NOT_SUPPORTED;
        }
        if (!anywhere && overwrite) {
                /*
                 * Create a temporary VM map to hold the old mappings in the
                 * affected area while we create the new one.
                 * This avoids releasing the VM map lock in
                 * vm_map_entry_delete() and allows atomicity
                 * when we want to replace some mappings with a new one.
                 * It also allows us to restore the old VM mappings if the
                 * new mapping fails.
                 */
                zap_old_map = vm_map_create(PMAP_NULL,
                    *address,
                    *address + size,
                    map->hdr.entries_pageable);
                vm_map_set_page_shift(zap_old_map, VM_MAP_PAGE_SHIFT(map));
                vm_map_disable_hole_optimization(zap_old_map);
        }

        fourk_start = *address;
        fourk_size = size;
        fourk_end = fourk_start + fourk_size;

        start = vm_map_trunc_page(*address, VM_MAP_PAGE_MASK(map));
        end = vm_map_round_page(fourk_end, VM_MAP_PAGE_MASK(map));
        size = end - start;

        if (anywhere) {
                return KERN_NOT_SUPPORTED;
        } else {
                /*
                 *      Verify that:
                 *              the address doesn't itself violate
                 *              the mask requirement.
                 */

                vm_map_lock(map);
                map_locked = TRUE;
                if ((start & mask) != 0) {
                        RETURN(KERN_NO_SPACE);
                }

                /*
                 *      ...     the address is within bounds
                 */

                end = start + size;

                if ((start < effective_min_offset) ||
                    (end > effective_max_offset) ||
                    (start >= end)) {
                        RETURN(KERN_INVALID_ADDRESS);
                }

                if (overwrite && zap_old_map != VM_MAP_NULL) {
                        /*
                         * Fixed mapping and "overwrite" flag: attempt to
                         * remove all existing mappings in the specified
                         * address range, saving them in our "zap_old_map".
                         */
                        (void) vm_map_delete(map, start, end,
                            (VM_MAP_REMOVE_SAVE_ENTRIES |
                            VM_MAP_REMOVE_NO_MAP_ALIGN),
                            zap_old_map);
                }

                /*
                 *      ...     the starting address isn't allocated
                 */
                if (vm_map_lookup_entry(map, start, &entry)) {
                        vm_object_t cur_object, shadow_object;

                        /*
                         * We might already some 4K mappings
                         * in a 16K page here.
                         */

                        if (entry->vme_end - entry->vme_start
                            != SIXTEENK_PAGE_SIZE) {
                                RETURN(KERN_NO_SPACE);
                        }
                        if (entry->is_sub_map) {
                                RETURN(KERN_NO_SPACE);
                        }
                        if (VME_OBJECT(entry) == VM_OBJECT_NULL) {
                                RETURN(KERN_NO_SPACE);
                        }

                        /* go all the way down the shadow chain */
                        cur_object = VME_OBJECT(entry);
                        vm_object_lock(cur_object);
                        while (cur_object->shadow != VM_OBJECT_NULL) {
                                shadow_object = cur_object->shadow;
                                vm_object_lock(shadow_object);
                                vm_object_unlock(cur_object);
                                cur_object = shadow_object;
                                shadow_object = VM_OBJECT_NULL;
                        }
                        if (cur_object->internal ||
                            cur_object->pager == NULL) {
                                vm_object_unlock(cur_object);
                                RETURN(KERN_NO_SPACE);
                        }
                        if (cur_object->pager->mo_pager_ops
                            != &fourk_pager_ops) {
                                vm_object_unlock(cur_object);
                                RETURN(KERN_NO_SPACE);
                        }
                        fourk_object = cur_object;
                        fourk_mem_obj = fourk_object->pager;

                        /* keep the "4K" object alive */
                        vm_object_reference_locked(fourk_object);
                        memory_object_reference(fourk_mem_obj);
                        vm_object_unlock(fourk_object);

                        /* merge permissions */
                        entry->protection |= cur_protection;
                        entry->max_protection |= max_protection;
                        if ((entry->protection & (VM_PROT_WRITE |
                            VM_PROT_EXECUTE)) ==
                            (VM_PROT_WRITE | VM_PROT_EXECUTE) &&
                            fourk_binary_compatibility_unsafe &&
                            fourk_binary_compatibility_allow_wx) {
                                /* write+execute: need to be "jit" */
                                entry->used_for_jit = TRUE;
                        }
                        goto map_in_fourk_pager;
                }

                /*
                 *      ...     the next region doesn't overlap the
                 *              end point.
                 */

                if ((entry->vme_next != vm_map_to_entry(map)) &&
                    (entry->vme_next->vme_start < end)) {
                        RETURN(KERN_NO_SPACE);
                }
        }

        /*
         *      At this point,
         *              "start" and "end" should define the endpoints of the
         *                      available new range, and
         *              "entry" should refer to the region before the new
         *                      range, and
         *
         *              the map should be locked.
         */

        /* create a new "4K" pager */
        fourk_mem_obj = fourk_pager_create();
        fourk_object = fourk_pager_to_vm_object(fourk_mem_obj);
        assert(fourk_object);

        /* keep the "4" object alive */
        vm_object_reference(fourk_object);

        /* create a "copy" object, to map the "4K" object copy-on-write */
        fourk_copy = TRUE;
        result = vm_object_copy_strategically(fourk_object,
            0,
            end - start,
            &copy_object,
            &copy_offset,
            &fourk_copy);
        assert(result == KERN_SUCCESS);
        assert(copy_object != VM_OBJECT_NULL);
        assert(copy_offset == 0);

        /* map the "4K" pager's copy object */
        new_entry =
            vm_map_entry_insert(map, entry,
            vm_map_trunc_page(start,
            VM_MAP_PAGE_MASK(map)),
            vm_map_round_page(end,
            VM_MAP_PAGE_MASK(map)),
            copy_object,
            0,                         /* offset */
            FALSE,                         /* needs_copy */
            FALSE,
            FALSE,
            cur_protection, max_protection,
            VM_BEHAVIOR_DEFAULT,
            (entry_for_jit && !VM_MAP_POLICY_ALLOW_JIT_INHERIT(map) ?
            VM_INHERIT_NONE : inheritance),
            0,
            no_cache,
            permanent,
            no_copy_on_read,
            superpage_size,
            clear_map_aligned,
            is_submap,
            FALSE,                         /* jit */
            alias,
            translated_allow_execute);
        entry = new_entry;

#if VM_MAP_DEBUG_FOURK
        if (vm_map_debug_fourk) {
                printf("FOURK_PAGER: map %p [0x%llx:0x%llx] new pager %p\n",
                    map,
                    (uint64_t) entry->vme_start,
                    (uint64_t) entry->vme_end,
                    fourk_mem_obj);
        }
#endif /* VM_MAP_DEBUG_FOURK */

        new_mapping_established = TRUE;

map_in_fourk_pager:
        /* "map" the original "object" where it belongs in the "4K" pager */
        fourk_pager_offset = (fourk_start & SIXTEENK_PAGE_MASK);
        fourk_pager_index_start = (int) (fourk_pager_offset / FOURK_PAGE_SIZE);
        if (fourk_size > SIXTEENK_PAGE_SIZE) {
                fourk_pager_index_num = 4;
        } else {
                fourk_pager_index_num = (int) (fourk_size / FOURK_PAGE_SIZE);
        }
        if (fourk_pager_index_start + fourk_pager_index_num > 4) {
                fourk_pager_index_num = 4 - fourk_pager_index_start;
        }
        for (cur_idx = 0;
            cur_idx < fourk_pager_index_num;
            cur_idx++) {
                vm_object_t             old_object;
                vm_object_offset_t      old_offset;

                kr = fourk_pager_populate(fourk_mem_obj,
                    TRUE,                       /* overwrite */
                    fourk_pager_index_start + cur_idx,
                    object,
                    (object
                    ? (offset +
                    (cur_idx * FOURK_PAGE_SIZE))
                    : 0),
                    &old_object,
                    &old_offset);
#if VM_MAP_DEBUG_FOURK
                if (vm_map_debug_fourk) {
                        if (old_object == (vm_object_t) -1 &&
                            old_offset == (vm_object_offset_t) -1) {
                                printf("FOURK_PAGER: map %p [0x%llx:0x%llx] "
                                    "pager [%p:0x%llx] "
                                    "populate[%d] "
                                    "[object:%p,offset:0x%llx]\n",
                                    map,
                                    (uint64_t) entry->vme_start,
                                    (uint64_t) entry->vme_end,
                                    fourk_mem_obj,
                                    VME_OFFSET(entry),
                                    fourk_pager_index_start + cur_idx,
                                    object,
                                    (object
                                    ? (offset + (cur_idx * FOURK_PAGE_SIZE))
                                    : 0));
                        } else {
                                printf("FOURK_PAGER: map %p [0x%llx:0x%llx] "
                                    "pager [%p:0x%llx] "
                                    "populate[%d] [object:%p,offset:0x%llx] "
                                    "old [%p:0x%llx]\n",
                                    map,
                                    (uint64_t) entry->vme_start,
                                    (uint64_t) entry->vme_end,
                                    fourk_mem_obj,
                                    VME_OFFSET(entry),
                                    fourk_pager_index_start + cur_idx,
                                    object,
                                    (object
                                    ? (offset + (cur_idx * FOURK_PAGE_SIZE))
                                    : 0),
                                    old_object,
                                    old_offset);
                        }
                }
#endif /* VM_MAP_DEBUG_FOURK */

                assert(kr == KERN_SUCCESS);
                if (object != old_object &&
                    object != VM_OBJECT_NULL &&
                    object != (vm_object_t) -1) {
                        vm_object_reference(object);
                }
                if (object != old_object &&
                    old_object != VM_OBJECT_NULL &&
                    old_object != (vm_object_t) -1) {
                        vm_object_deallocate(old_object);
                }
        }

BailOut:
        assert(map_locked == TRUE);

        if (result == KERN_SUCCESS) {
                vm_prot_t pager_prot;
                memory_object_t pager;

#if DEBUG
                if (pmap_empty &&
                    !(vmk_flags.vmkf_no_pmap_check)) {
                        assert(vm_map_pmap_is_empty(map,
                            *address,
                            *address + size));
                }
#endif /* DEBUG */

                /*
                 * For "named" VM objects, let the pager know that the
                 * memory object is being mapped.  Some pagers need to keep
                 * track of this, to know when they can reclaim the memory
                 * object, for example.
                 * VM calls memory_object_map() for each mapping (specifying
                 * the protection of each mapping) and calls
                 * memory_object_last_unmap() when all the mappings are gone.
                 */
                pager_prot = max_protection;
                if (needs_copy) {
                        /*
                         * Copy-On-Write mapping: won't modify
                         * the memory object.
                         */
                        pager_prot &= ~VM_PROT_WRITE;
                }
                if (!is_submap &&
                    object != VM_OBJECT_NULL &&
                    object->named &&
                    object->pager != MEMORY_OBJECT_NULL) {
                        vm_object_lock(object);
                        pager = object->pager;
                        if (object->named &&
                            pager != MEMORY_OBJECT_NULL) {
                                assert(object->pager_ready);
                                vm_object_mapping_wait(object, THREAD_UNINT);
                                vm_object_mapping_begin(object);
                                vm_object_unlock(object);

                                kr = memory_object_map(pager, pager_prot);
                                assert(kr == KERN_SUCCESS);

                                vm_object_lock(object);
                                vm_object_mapping_end(object);
                        }
                        vm_object_unlock(object);
                }
                if (!is_submap &&
                    fourk_object != VM_OBJECT_NULL &&
                    fourk_object->named &&
                    fourk_object->pager != MEMORY_OBJECT_NULL) {
                        vm_object_lock(fourk_object);
                        pager = fourk_object->pager;
                        if (fourk_object->named &&
                            pager != MEMORY_OBJECT_NULL) {
                                assert(fourk_object->pager_ready);
                                vm_object_mapping_wait(fourk_object,
                                    THREAD_UNINT);
                                vm_object_mapping_begin(fourk_object);
                                vm_object_unlock(fourk_object);

                                kr = memory_object_map(pager, VM_PROT_READ);
                                assert(kr == KERN_SUCCESS);

                                vm_object_lock(fourk_object);
                                vm_object_mapping_end(fourk_object);
                        }
                        vm_object_unlock(fourk_object);
                }
        }

        if (fourk_object != VM_OBJECT_NULL) {
                vm_object_deallocate(fourk_object);
                fourk_object = VM_OBJECT_NULL;
                memory_object_deallocate(fourk_mem_obj);
                fourk_mem_obj = MEMORY_OBJECT_NULL;
        }

        assert(map_locked == TRUE);

        if (!keep_map_locked) {
                vm_map_unlock(map);
                map_locked = FALSE;
        }

        /*
         * We can't hold the map lock if we enter this block.
         */

        if (result == KERN_SUCCESS) {
                /*      Wire down the new entry if the user
                 *      requested all new map entries be wired.
                 */
                if ((map->wiring_required) || (superpage_size)) {
                        assert(!keep_map_locked);
                        pmap_empty = FALSE; /* pmap won't be empty */
                        kr = vm_map_wire_kernel(map, start, end,
                            new_entry->protection, VM_KERN_MEMORY_MLOCK,
                            TRUE);
                        result = kr;
                }

        }

        if (result != KERN_SUCCESS) {
                if (new_mapping_established) {
                        /*
                         * We have to get rid of the new mappings since we
                         * won't make them available to the user.
                         * Try and do that atomically, to minimize the risk
                         * that someone else create new mappings that range.
                         */
                        zap_new_map = vm_map_create(PMAP_NULL,
                            *address,
                            *address + size,
                            map->hdr.entries_pageable);
                        vm_map_set_page_shift(zap_new_map,
                            VM_MAP_PAGE_SHIFT(map));
                        vm_map_disable_hole_optimization(zap_new_map);

                        if (!map_locked) {
                                vm_map_lock(map);
                                map_locked = TRUE;
                        }
                        (void) vm_map_delete(map, *address, *address + size,
                            (VM_MAP_REMOVE_SAVE_ENTRIES |
                            VM_MAP_REMOVE_NO_MAP_ALIGN),
                            zap_new_map);
                }
                if (zap_old_map != VM_MAP_NULL &&
                    zap_old_map->hdr.nentries != 0) {
                        vm_map_entry_t  entry1, entry2;

                        /*
                         * The new mapping failed.  Attempt to restore
                         * the old mappings, saved in the "zap_old_map".
                         */
                        if (!map_locked) {
                                vm_map_lock(map);
                                map_locked = TRUE;
                        }

                        /* first check if the coast is still clear */
                        start = vm_map_first_entry(zap_old_map)->vme_start;
                        end = vm_map_last_entry(zap_old_map)->vme_end;
                        if (vm_map_lookup_entry(map, start, &entry1) ||
                            vm_map_lookup_entry(map, end, &entry2) ||
                            entry1 != entry2) {
                                /*
                                 * Part of that range has already been
                                 * re-mapped:  we can't restore the old
                                 * mappings...
                                 */
                                vm_map_enter_restore_failures++;
                        } else {
                                /*
                                 * Transfer the saved map entries from
                                 * "zap_old_map" to the original "map",
                                 * inserting them all after "entry1".
                                 */
                                for (entry2 = vm_map_first_entry(zap_old_map);
                                    entry2 != vm_map_to_entry(zap_old_map);
                                    entry2 = vm_map_first_entry(zap_old_map)) {
                                        vm_map_size_t entry_size;

                                        entry_size = (entry2->vme_end -
                                            entry2->vme_start);
                                        vm_map_store_entry_unlink(zap_old_map,
                                            entry2);
                                        zap_old_map->size -= entry_size;
                                        vm_map_store_entry_link(map, entry1, entry2,
                                            VM_MAP_KERNEL_FLAGS_NONE);
                                        map->size += entry_size;
                                        entry1 = entry2;
                                }
                                if (map->wiring_required) {
                                        /*
                                         * XXX TODO: we should rewire the
                                         * old pages here...
                                         */
                                }
                                vm_map_enter_restore_successes++;
                        }
                }
        }

        /*
         * The caller is responsible for releasing the lock if it requested to
         * keep the map locked.
         */
        if (map_locked && !keep_map_locked) {
                vm_map_unlock(map);
        }

        /*
         * Get rid of the "zap_maps" and all the map entries that
         * they may still contain.
         */
        if (zap_old_map != VM_MAP_NULL) {
                vm_map_destroy(zap_old_map, VM_MAP_REMOVE_NO_PMAP_CLEANUP);
                zap_old_map = VM_MAP_NULL;
        }
        if (zap_new_map != VM_MAP_NULL) {
                vm_map_destroy(zap_new_map, VM_MAP_REMOVE_NO_PMAP_CLEANUP);
                zap_new_map = VM_MAP_NULL;
        }

        return result;

#undef  RETURN
}
#endif /* __arm64__ */

/*
 * Counters for the prefault optimization.
 */
int64_t vm_prefault_nb_pages = 0;
int64_t vm_prefault_nb_bailout = 0;

static kern_return_t
vm_map_enter_mem_object_helper(
        vm_map_t                target_map,
        vm_map_offset_t         *address,
        vm_map_size_t           initial_size,
        vm_map_offset_t         mask,
        int                     flags,
        vm_map_kernel_flags_t   vmk_flags,
        vm_tag_t                tag,
        ipc_port_t              port,
        vm_object_offset_t      offset,
        boolean_t               copy,
        vm_prot_t               cur_protection,
        vm_prot_t               max_protection,
        vm_inherit_t            inheritance,
        upl_page_list_ptr_t     page_list,
        unsigned int            page_list_count)
{
        vm_map_address_t        map_addr;
        vm_map_size_t           map_size;
        vm_object_t             object;
        vm_object_size_t        size;
        kern_return_t           result;
        boolean_t               mask_cur_protection, mask_max_protection;
        boolean_t               kernel_prefault, try_prefault = (page_list_count != 0);
        vm_map_offset_t         offset_in_mapping = 0;
#if __arm64__
        boolean_t               fourk = vmk_flags.vmkf_fourk;
#endif /* __arm64__ */

        if (VM_MAP_PAGE_SHIFT(target_map) < PAGE_SHIFT) {
                /* XXX TODO4K prefaulting depends on page size... */
                try_prefault = FALSE;
        }

        assertf(vmk_flags.__vmkf_unused == 0, "vmk_flags unused=0x%x\n", vmk_flags.__vmkf_unused);

        mask_cur_protection = cur_protection & VM_PROT_IS_MASK;
        mask_max_protection = max_protection & VM_PROT_IS_MASK;
        cur_protection &= ~VM_PROT_IS_MASK;
        max_protection &= ~VM_PROT_IS_MASK;

        /*
         * Check arguments for validity
         */
        if ((target_map == VM_MAP_NULL) ||
            (cur_protection & ~VM_PROT_ALL) ||
            (max_protection & ~VM_PROT_ALL) ||
            (inheritance > VM_INHERIT_LAST_VALID) ||
            (try_prefault && (copy || !page_list)) ||
            initial_size == 0) {
                return KERN_INVALID_ARGUMENT;
        }

#if __arm64__
        if (fourk && VM_MAP_PAGE_SHIFT(target_map) < PAGE_SHIFT) {
                /* no "fourk" if map is using a sub-page page size */
                fourk = FALSE;
        }
        if (fourk) {
                map_addr = vm_map_trunc_page(*address, FOURK_PAGE_MASK);
                map_size = vm_map_round_page(initial_size, FOURK_PAGE_MASK);
        } else
#endif /* __arm64__ */
        {
                map_addr = vm_map_trunc_page(*address,
                    VM_MAP_PAGE_MASK(target_map));
                map_size = vm_map_round_page(initial_size,
                    VM_MAP_PAGE_MASK(target_map));
        }
        size = vm_object_round_page(initial_size);

        /*
         * Find the vm object (if any) corresponding to this port.
         */
        if (!IP_VALID(port)) {
                object = VM_OBJECT_NULL;
                offset = 0;
                copy = FALSE;
        } else if (ip_kotype(port) == IKOT_NAMED_ENTRY) {
                vm_named_entry_t        named_entry;
                vm_object_offset_t      data_offset;

                named_entry = (vm_named_entry_t) ip_get_kobject(port);

                if (flags & (VM_FLAGS_RETURN_DATA_ADDR |
                    VM_FLAGS_RETURN_4K_DATA_ADDR)) {
                        data_offset = named_entry->data_offset;
                        offset += named_entry->data_offset;
                } else {
                        data_offset = 0;
                }

                /* a few checks to make sure user is obeying rules */
                if (size == 0) {
                        if (offset >= named_entry->size) {
                                return KERN_INVALID_RIGHT;
                        }
                        size = named_entry->size - offset;
                }
                if (mask_max_protection) {
                        max_protection &= named_entry->protection;
                }
                if (mask_cur_protection) {
                        cur_protection &= named_entry->protection;
                }
                if ((named_entry->protection & max_protection) !=
                    max_protection) {
                        return KERN_INVALID_RIGHT;
                }
                if ((named_entry->protection & cur_protection) !=
                    cur_protection) {
                        return KERN_INVALID_RIGHT;
                }
                if (offset + size < offset) {
                        /* overflow */
                        return KERN_INVALID_ARGUMENT;
                }
                if (named_entry->size < (offset + initial_size)) {
                        return KERN_INVALID_ARGUMENT;
                }

                if (named_entry->is_copy) {
                        /* for a vm_map_copy, we can only map it whole */
                        if ((size != named_entry->size) &&
                            (vm_map_round_page(size,
                            VM_MAP_PAGE_MASK(target_map)) ==
                            named_entry->size)) {
                                /* XXX FBDP use the rounded size... */
                                size = vm_map_round_page(
                                        size,
                                        VM_MAP_PAGE_MASK(target_map));
                        }
                }

                /* the callers parameter offset is defined to be the */
                /* offset from beginning of named entry offset in object */
                offset = offset + named_entry->offset;

                if (!VM_MAP_PAGE_ALIGNED(size,
                    VM_MAP_PAGE_MASK(target_map))) {
                        /*
                         * Let's not map more than requested;
                         * vm_map_enter() will handle this "not map-aligned"
                         * case.
                         */
                        map_size = size;
                }

                named_entry_lock(named_entry);
                if (named_entry->is_sub_map) {
                        vm_map_t                submap;

                        if (flags & (VM_FLAGS_RETURN_DATA_ADDR |
                            VM_FLAGS_RETURN_4K_DATA_ADDR)) {
                                panic("VM_FLAGS_RETURN_DATA_ADDR not expected for submap.");
                        }

                        submap = named_entry->backing.map;
                        vm_map_reference(submap);
                        named_entry_unlock(named_entry);

                        vmk_flags.vmkf_submap = TRUE;

                        result = vm_map_enter(target_map,
                            &map_addr,
                            map_size,
                            mask,
                            flags,
                            vmk_flags,
                            tag,
                            (vm_object_t)(uintptr_t) submap,
                            offset,
                            copy,
                            cur_protection,
                            max_protection,
                            inheritance);
                        if (result != KERN_SUCCESS) {
                                vm_map_deallocate(submap);
                        } else {
                                /*
                                 * No need to lock "submap" just to check its
                                 * "mapped" flag: that flag is never reset
                                 * once it's been set and if we race, we'll
                                 * just end up setting it twice, which is OK.
                                 */
                                if (submap->mapped_in_other_pmaps == FALSE &&
                                    vm_map_pmap(submap) != PMAP_NULL &&
                                    vm_map_pmap(submap) !=
                                    vm_map_pmap(target_map)) {
                                        /*
                                         * This submap is being mapped in a map
                                         * that uses a different pmap.
                                         * Set its "mapped_in_other_pmaps" flag
                                         * to indicate that we now need to
                                         * remove mappings from all pmaps rather
                                         * than just the submap's pmap.
                                         */
                                        vm_map_lock(submap);
                                        submap->mapped_in_other_pmaps = TRUE;
                                        vm_map_unlock(submap);
                                }
                                *address = map_addr;
                        }
                        return result;
                } else if (named_entry->is_copy) {
                        kern_return_t   kr;
                        vm_map_copy_t   copy_map;
                        vm_map_entry_t  copy_entry;
                        vm_map_offset_t copy_addr;
                        vm_map_copy_t   target_copy_map;
                        vm_map_offset_t overmap_start, overmap_end;
                        vm_map_offset_t trimmed_start;
                        vm_map_size_t   target_size;

                        if (flags & ~(VM_FLAGS_FIXED |
                            VM_FLAGS_ANYWHERE |
                            VM_FLAGS_OVERWRITE |
                            VM_FLAGS_RETURN_4K_DATA_ADDR |
                            VM_FLAGS_RETURN_DATA_ADDR |
                            VM_FLAGS_ALIAS_MASK)) {
                                named_entry_unlock(named_entry);
                                return KERN_INVALID_ARGUMENT;
                        }

                        copy_map = named_entry->backing.copy;
                        assert(copy_map->type == VM_MAP_COPY_ENTRY_LIST);
                        if (copy_map->type != VM_MAP_COPY_ENTRY_LIST) {
                                /* unsupported type; should not happen */
                                printf("vm_map_enter_mem_object: "
                                    "memory_entry->backing.copy "
                                    "unsupported type 0x%x\n",
                                    copy_map->type);
                                named_entry_unlock(named_entry);
                                return KERN_INVALID_ARGUMENT;
                        }

                        if (VM_MAP_PAGE_SHIFT(target_map) != copy_map->cpy_hdr.page_shift) {
                                DEBUG4K_SHARE("copy_map %p offset %llx size 0x%llx pgshift %d -> target_map %p pgshift %d\n", copy_map, offset, (uint64_t)map_size, copy_map->cpy_hdr.page_shift, target_map, VM_MAP_PAGE_SHIFT(target_map));
                        }

                        if (flags & (VM_FLAGS_RETURN_DATA_ADDR |
                            VM_FLAGS_RETURN_4K_DATA_ADDR)) {
                                offset_in_mapping = offset & VM_MAP_PAGE_MASK(target_map);
                                if (flags & VM_FLAGS_RETURN_4K_DATA_ADDR) {
                                        offset_in_mapping &= ~((signed)(0xFFF));
                                }
                        }

                        target_copy_map = VM_MAP_COPY_NULL;
                        target_size = copy_map->size;
                        overmap_start = 0;
                        overmap_end = 0;
                        trimmed_start = 0;
                        if (copy_map->cpy_hdr.page_shift != VM_MAP_PAGE_SHIFT(target_map)) {
                                DEBUG4K_ADJUST("adjusting...\n");
                                kr = vm_map_copy_adjust_to_target(
                                        copy_map,
                                        offset /* includes data_offset */,
                                        initial_size,
                                        target_map,
                                        copy,
                                        &target_copy_map,
                                        &overmap_start,
                                        &overmap_end,
                                        &trimmed_start);
                                if (kr != KERN_SUCCESS) {
                                        named_entry_unlock(named_entry);
                                        return kr;
                                }
                                target_size = target_copy_map->size;
                                if (trimmed_start >= data_offset) {
                                        data_offset = offset & VM_MAP_PAGE_MASK(target_map);
                                } else {
                                        data_offset -= trimmed_start;
                                }
                        } else {
                                target_copy_map = copy_map;
                        }

                        /* reserve a contiguous range */
                        kr = vm_map_enter(target_map,
                            &map_addr,
                            vm_map_round_page(target_size, VM_MAP_PAGE_MASK(target_map)),
                            mask,
                            flags & (VM_FLAGS_ANYWHERE |
                            VM_FLAGS_OVERWRITE |
                            VM_FLAGS_RETURN_4K_DATA_ADDR |
                            VM_FLAGS_RETURN_DATA_ADDR),
                            vmk_flags,
                            tag,
                            VM_OBJECT_NULL,
                            0,
                            FALSE,               /* copy */
                            cur_protection,
                            max_protection,
                            inheritance);
                        if (kr != KERN_SUCCESS) {
                                DEBUG4K_ERROR("kr 0x%x\n", kr);
                                if (target_copy_map != copy_map) {
                                        vm_map_copy_discard(target_copy_map);
                                        target_copy_map = VM_MAP_COPY_NULL;
                                }
                                named_entry_unlock(named_entry);
                                return kr;
                        }

                        copy_addr = map_addr;

                        for (copy_entry = vm_map_copy_first_entry(target_copy_map);
                            copy_entry != vm_map_copy_to_entry(target_copy_map);
                            copy_entry = copy_entry->vme_next) {
                                int                     remap_flags;
                                vm_map_kernel_flags_t   vmk_remap_flags;
                                vm_map_t                copy_submap;
                                vm_object_t             copy_object;
                                vm_map_size_t           copy_size;
                                vm_object_offset_t      copy_offset;
                                int                     copy_vm_alias;

                                remap_flags = 0;
                                vmk_remap_flags = VM_MAP_KERNEL_FLAGS_NONE;

                                copy_object = VME_OBJECT(copy_entry);
                                copy_offset = VME_OFFSET(copy_entry);
                                copy_size = (copy_entry->vme_end -
                                    copy_entry->vme_start);
                                VM_GET_FLAGS_ALIAS(flags, copy_vm_alias);
                                if (copy_vm_alias == 0) {
                                        /*
                                         * Caller does not want a specific
                                         * alias for this new mapping:  use
                                         * the alias of the original mapping.
                                         */
                                        copy_vm_alias = VME_ALIAS(copy_entry);
                                }

                                /* sanity check */
                                if ((copy_addr + copy_size) >
                                    (map_addr +
                                    overmap_start + overmap_end +
                                    named_entry->size /* XXX full size */)) {
                                        /* over-mapping too much !? */
                                        kr = KERN_INVALID_ARGUMENT;
                                        DEBUG4K_ERROR("kr 0x%x\n", kr);
                                        /* abort */
                                        break;
                                }

                                /* take a reference on the object */
                                if (copy_entry->is_sub_map) {
                                        vmk_remap_flags.vmkf_submap = TRUE;
                                        copy_submap = VME_SUBMAP(copy_entry);
                                        vm_map_lock(copy_submap);
                                        vm_map_reference(copy_submap);
                                        vm_map_unlock(copy_submap);
                                        copy_object = (vm_object_t)(uintptr_t) copy_submap;
                                } else if (!copy &&
                                    copy_object != VM_OBJECT_NULL &&
                                    (copy_entry->needs_copy ||
                                    copy_object->shadowed ||
                                    (!copy_object->true_share &&
                                    !copy_entry->is_shared &&
                                    copy_object->vo_size > copy_size))) {
                                        /*
                                         * We need to resolve our side of this
                                         * "symmetric" copy-on-write now; we
                                         * need a new object to map and share,
                                         * instead of the current one which
                                         * might still be shared with the
                                         * original mapping.
                                         *
                                         * Note: A "vm_map_copy_t" does not
                                         * have a lock but we're protected by
                                         * the named entry's lock here.
                                         */
                                        // assert(copy_object->copy_strategy == MEMORY_OBJECT_COPY_SYMMETRIC);
                                        VME_OBJECT_SHADOW(copy_entry, copy_size);
                                        if (!copy_entry->needs_copy &&
                                            copy_entry->protection & VM_PROT_WRITE) {
                                                vm_prot_t prot;

                                                prot = copy_entry->protection & ~VM_PROT_WRITE;
                                                vm_object_pmap_protect(copy_object,
                                                    copy_offset,
                                                    copy_size,
                                                    PMAP_NULL,
                                                    PAGE_SIZE,
                                                    0,
                                                    prot);
                                        }

                                        copy_entry->needs_copy = FALSE;
                                        copy_entry->is_shared = TRUE;
                                        copy_object = VME_OBJECT(copy_entry);
                                        copy_offset = VME_OFFSET(copy_entry);
                                        vm_object_lock(copy_object);
                                        vm_object_reference_locked(copy_object);
                                        if (copy_object->copy_strategy == MEMORY_OBJECT_COPY_SYMMETRIC) {
                                                /* we're about to make a shared mapping of this object */
                                                copy_object->copy_strategy = MEMORY_OBJECT_COPY_DELAY;
                                                copy_object->true_share = TRUE;
                                        }
                                        vm_object_unlock(copy_object);
                                } else {
                                        /*
                                         * We already have the right object
                                         * to map.
                                         */
                                        copy_object = VME_OBJECT(copy_entry);
                                        vm_object_reference(copy_object);
                                }

                                /* over-map the object into destination */
                                remap_flags |= flags;
                                remap_flags |= VM_FLAGS_FIXED;
                                remap_flags |= VM_FLAGS_OVERWRITE;
                                remap_flags &= ~VM_FLAGS_ANYWHERE;
                                if (!copy && !copy_entry->is_sub_map) {
                                        /*
                                         * copy-on-write should have been
                                         * resolved at this point, or we would
                                         * end up sharing instead of copying.
                                         */
                                        assert(!copy_entry->needs_copy);
                                }
#if XNU_TARGET_OS_OSX
                                if (copy_entry->used_for_jit) {
                                        vmk_remap_flags.vmkf_map_jit = TRUE;
                                }
#endif /* XNU_TARGET_OS_OSX */

                                assertf((copy_vm_alias & VME_ALIAS_MASK) == copy_vm_alias,
                                    "VM Tag truncated from 0x%x to 0x%x\n", copy_vm_alias, (copy_vm_alias & VME_ALIAS_MASK));
                                kr = vm_map_enter(target_map,
                                    &copy_addr,
                                    copy_size,
                                    (vm_map_offset_t) 0,
                                    remap_flags,
                                    vmk_remap_flags,
                                    (vm_tag_t) copy_vm_alias, /* see comment at end of vm_fault_unwire re. cast*/
                                    copy_object,
                                    copy_offset,
                                    ((copy_object == NULL) ? FALSE : copy),
                                    cur_protection,
                                    max_protection,
                                    inheritance);
                                if (kr != KERN_SUCCESS) {
                                        DEBUG4K_SHARE("failed kr 0x%x\n", kr);
                                        if (copy_entry->is_sub_map) {
                                                vm_map_deallocate(copy_submap);
                                        } else {
                                                vm_object_deallocate(copy_object);
                                        }
                                        /* abort */
                                        break;
                                }

                                /* next mapping */
                                copy_addr += copy_size;
                        }

                        if (kr == KERN_SUCCESS) {
                                if (flags & (VM_FLAGS_RETURN_DATA_ADDR |
                                    VM_FLAGS_RETURN_4K_DATA_ADDR)) {
                                        *address = map_addr + offset_in_mapping;
                                } else {
                                        *address = map_addr;
                                }
                                if (overmap_start) {
                                        *address += overmap_start;
                                        DEBUG4K_SHARE("map %p map_addr 0x%llx offset_in_mapping 0x%llx overmap_start 0x%llx -> *address 0x%llx\n", target_map, (uint64_t)map_addr, (uint64_t) offset_in_mapping, (uint64_t)overmap_start, (uint64_t)*address);
                                }
                        }
                        named_entry_unlock(named_entry);
                        if (target_copy_map != copy_map) {
                                vm_map_copy_discard(target_copy_map);
                                target_copy_map = VM_MAP_COPY_NULL;
                        }

                        if (kr != KERN_SUCCESS) {
                                if (!(flags & VM_FLAGS_OVERWRITE)) {
                                        /* deallocate the contiguous range */
                                        (void) vm_deallocate(target_map,
                                            map_addr,
                                            map_size);
                                }
                        }

                        return kr;
                }

                if (named_entry->is_object) {
                        unsigned int    access;
                        vm_prot_t       protections;
                        unsigned int    wimg_mode;

                        /* we are mapping a VM object */

                        protections = named_entry->protection & VM_PROT_ALL;
                        access = GET_MAP_MEM(named_entry->protection);

                        if (flags & (VM_FLAGS_RETURN_DATA_ADDR |
                            VM_FLAGS_RETURN_4K_DATA_ADDR)) {
                                offset_in_mapping = offset - VM_MAP_TRUNC_PAGE(offset, VM_MAP_PAGE_MASK(target_map));
                                if (flags & VM_FLAGS_RETURN_4K_DATA_ADDR) {
                                        offset_in_mapping &= ~((signed)(0xFFF));
                                }
                                offset = VM_MAP_TRUNC_PAGE(offset, VM_MAP_PAGE_MASK(target_map));
                                map_size = VM_MAP_ROUND_PAGE((offset + offset_in_mapping + initial_size) - offset, VM_MAP_PAGE_MASK(target_map));
                        }

                        object = vm_named_entry_to_vm_object(named_entry);
                        assert(object != VM_OBJECT_NULL);
                        vm_object_lock(object);
                        named_entry_unlock(named_entry);

                        vm_object_reference_locked(object);

                        wimg_mode = object->wimg_bits;
                        vm_prot_to_wimg(access, &wimg_mode);
                        if (object->wimg_bits != wimg_mode) {
                                vm_object_change_wimg_mode(object, wimg_mode);
                        }

                        vm_object_unlock(object);
                } else {
                        panic("invalid VM named entry %p", named_entry);
                }
        } else if (ip_kotype(port) == IKOT_MEMORY_OBJECT) {
                /*
                 * JMM - This is temporary until we unify named entries
                 * and raw memory objects.
                 *
                 * Detected fake ip_kotype for a memory object.  In
                 * this case, the port isn't really a port at all, but
                 * instead is just a raw memory object.
                 */
                if (flags & (VM_FLAGS_RETURN_DATA_ADDR |
                    VM_FLAGS_RETURN_4K_DATA_ADDR)) {
                        panic("VM_FLAGS_RETURN_DATA_ADDR not expected for raw memory object.");
                }

                object = memory_object_to_vm_object((memory_object_t)port);
                if (object == VM_OBJECT_NULL) {
                        return KERN_INVALID_OBJECT;
                }
                vm_object_reference(object);

                /* wait for object (if any) to be ready */
                if (object != VM_OBJECT_NULL) {
                        if (object == kernel_object) {
                                printf("Warning: Attempt to map kernel object"
                                    " by a non-private kernel entity\n");
                                return KERN_INVALID_OBJECT;
                        }
                        if (!object->pager_ready) {
                                vm_object_lock(object);

                                while (!object->pager_ready) {
                                        vm_object_wait(object,
                                            VM_OBJECT_EVENT_PAGER_READY,
                                            THREAD_UNINT);
                                        vm_object_lock(object);
                                }
                                vm_object_unlock(object);
                        }
                }
        } else {
                return KERN_INVALID_OBJECT;
        }

        if (object != VM_OBJECT_NULL &&
            object->named &&
            object->pager != MEMORY_OBJECT_NULL &&
            object->copy_strategy != MEMORY_OBJECT_COPY_NONE) {
                memory_object_t pager;
                vm_prot_t       pager_prot;
                kern_return_t   kr;

                /*
                 * For "named" VM objects, let the pager know that the
                 * memory object is being mapped.  Some pagers need to keep
                 * track of this, to know when they can reclaim the memory
                 * object, for example.
                 * VM calls memory_object_map() for each mapping (specifying
                 * the protection of each mapping) and calls
                 * memory_object_last_unmap() when all the mappings are gone.
                 */
                pager_prot = max_protection;
                if (copy) {
                        /*
                         * Copy-On-Write mapping: won't modify the
                         * memory object.
                         */
                        pager_prot &= ~VM_PROT_WRITE;
                }
                vm_object_lock(object);
                pager = object->pager;
                if (object->named &&
                    pager != MEMORY_OBJECT_NULL &&
                    object->copy_strategy != MEMORY_OBJECT_COPY_NONE) {
                        assert(object->pager_ready);
                        vm_object_mapping_wait(object, THREAD_UNINT);
                        vm_object_mapping_begin(object);
                        vm_object_unlock(object);

                        kr = memory_object_map(pager, pager_prot);
                        assert(kr == KERN_SUCCESS);

                        vm_object_lock(object);
                        vm_object_mapping_end(object);
                }
                vm_object_unlock(object);
        }

        /*
         *      Perform the copy if requested
         */

        if (copy) {
                vm_object_t             new_object;
                vm_object_offset_t      new_offset;

                result = vm_object_copy_strategically(object, offset,
                    map_size,
                    &new_object, &new_offset,
                    &copy);


                if (result == KERN_MEMORY_RESTART_COPY) {
                        boolean_t success;
                        boolean_t src_needs_copy;

                        /*
                         * XXX
                         * We currently ignore src_needs_copy.
                         * This really is the issue of how to make
                         * MEMORY_OBJECT_COPY_SYMMETRIC safe for
                         * non-kernel users to use. Solution forthcoming.
                         * In the meantime, since we don't allow non-kernel
                         * memory managers to specify symmetric copy,
                         * we won't run into problems here.
                         */
                        new_object = object;
                        new_offset = offset;
                        success = vm_object_copy_quickly(&new_object,
                            new_offset,
                            map_size,
                            &src_needs_copy,
                            &copy);
                        assert(success);
                        result = KERN_SUCCESS;
                }
                /*
                 *      Throw away the reference to the
                 *      original object, as it won't be mapped.
                 */

                vm_object_deallocate(object);

                if (result != KERN_SUCCESS) {
                        return result;
                }

                object = new_object;
                offset = new_offset;
        }

        /*
         * If non-kernel users want to try to prefault pages, the mapping and prefault
         * needs to be atomic.
         */
        kernel_prefault = (try_prefault && vm_kernel_map_is_kernel(target_map));
        vmk_flags.vmkf_keep_map_locked = (try_prefault && !kernel_prefault);

#if __arm64__
        if (fourk) {
                /* map this object in a "4K" pager */
                result = vm_map_enter_fourk(target_map,
                    &map_addr,
                    map_size,
                    (vm_map_offset_t) mask,
                    flags,
                    vmk_flags,
                    tag,
                    object,
                    offset,
                    copy,
                    cur_protection,
                    max_protection,
                    inheritance);
        } else
#endif /* __arm64__ */
        {
                result = vm_map_enter(target_map,
                    &map_addr, map_size,
                    (vm_map_offset_t)mask,
                    flags,
                    vmk_flags,
                    tag,
                    object, offset,
                    copy,
                    cur_protection, max_protection,
                    inheritance);
        }
        if (result != KERN_SUCCESS) {
                vm_object_deallocate(object);
        }

        /*
         * Try to prefault, and do not forget to release the vm map lock.
         */
        if (result == KERN_SUCCESS && try_prefault) {
                mach_vm_address_t va = map_addr;
                kern_return_t kr = KERN_SUCCESS;
                unsigned int i = 0;
                int pmap_options;

                pmap_options = kernel_prefault ? 0 : PMAP_OPTIONS_NOWAIT;
                if (object->internal) {
                        pmap_options |= PMAP_OPTIONS_INTERNAL;
                }

                for (i = 0; i < page_list_count; ++i) {
                        if (!UPL_VALID_PAGE(page_list, i)) {
                                if (kernel_prefault) {
                                        assertf(FALSE, "kernel_prefault && !UPL_VALID_PAGE");
                                        result = KERN_MEMORY_ERROR;
                                        break;
                                }
                        } else {
                                /*
                                 * If this function call failed, we should stop
                                 * trying to optimize, other calls are likely
                                 * going to fail too.
                                 *
                                 * We are not gonna report an error for such
                                 * failure though. That's an optimization, not
                                 * something critical.
                                 */
                                kr = pmap_enter_options(target_map->pmap,
                                    va, UPL_PHYS_PAGE(page_list, i),
                                    cur_protection, VM_PROT_NONE,
                                    0, TRUE, pmap_options, NULL);
                                if (kr != KERN_SUCCESS) {
                                        OSIncrementAtomic64(&vm_prefault_nb_bailout);
                                        if (kernel_prefault) {
                                                result = kr;
                                        }
                                        break;
                                }
                                OSIncrementAtomic64(&vm_prefault_nb_pages);
                        }

                        /* Next virtual address */
                        va += PAGE_SIZE;
                }
                if (vmk_flags.vmkf_keep_map_locked) {
                        vm_map_unlock(target_map);
                }
        }

        if (flags & (VM_FLAGS_RETURN_DATA_ADDR |
            VM_FLAGS_RETURN_4K_DATA_ADDR)) {
                *address = map_addr + offset_in_mapping;
        } else {
                *address = map_addr;
        }
        return result;
}

kern_return_t
vm_map_enter_mem_object(
        vm_map_t                target_map,
        vm_map_offset_t         *address,
        vm_map_size_t           initial_size,
        vm_map_offset_t         mask,
        int                     flags,
        vm_map_kernel_flags_t   vmk_flags,
        vm_tag_t                tag,
        ipc_port_t              port,
        vm_object_offset_t      offset,
        boolean_t               copy,
        vm_prot_t               cur_protection,
        vm_prot_t               max_protection,
        vm_inherit_t            inheritance)
{
        kern_return_t ret;

        ret = vm_map_enter_mem_object_helper(target_map,
            address,
            initial_size,
            mask,
            flags,
            vmk_flags,
            tag,
            port,
            offset,
            copy,
            cur_protection,
            max_protection,
            inheritance,
            NULL,
            0);

#if KASAN
        if (ret == KERN_SUCCESS && address && target_map->pmap == kernel_pmap) {
                kasan_notify_address(*address, initial_size);
        }
#endif

        return ret;
}

kern_return_t
vm_map_enter_mem_object_prefault(
        vm_map_t                target_map,
        vm_map_offset_t         *address,
        vm_map_size_t           initial_size,
        vm_map_offset_t         mask,
        int                     flags,
        vm_map_kernel_flags_t   vmk_flags,
        vm_tag_t                tag,
        ipc_port_t              port,
        vm_object_offset_t      offset,
        vm_prot_t               cur_protection,
        vm_prot_t               max_protection,
        upl_page_list_ptr_t     page_list,
        unsigned int            page_list_count)
{
        kern_return_t ret;

        ret = vm_map_enter_mem_object_helper(target_map,
            address,
            initial_size,
            mask,
            flags,
            vmk_flags,
            tag,
            port,
            offset,
            FALSE,
            cur_protection,
            max_protection,
            VM_INHERIT_DEFAULT,
            page_list,
            page_list_count);

#if KASAN
        if (ret == KERN_SUCCESS && address && target_map->pmap == kernel_pmap) {
                kasan_notify_address(*address, initial_size);
        }
#endif

        return ret;
}


kern_return_t
vm_map_enter_mem_object_control(
        vm_map_t                target_map,
        vm_map_offset_t         *address,
        vm_map_size_t           initial_size,
        vm_map_offset_t         mask,
        int                     flags,
        vm_map_kernel_flags_t   vmk_flags,
        vm_tag_t                tag,
        memory_object_control_t control,
        vm_object_offset_t      offset,
        boolean_t               copy,
        vm_prot_t               cur_protection,
        vm_prot_t               max_protection,
        vm_inherit_t            inheritance)
{
        vm_map_address_t        map_addr;
        vm_map_size_t           map_size;
        vm_object_t             object;
        vm_object_size_t        size;
        kern_return_t           result;
        memory_object_t         pager;
        vm_prot_t               pager_prot;
        kern_return_t           kr;
#if __arm64__
        boolean_t               fourk = vmk_flags.vmkf_fourk;
#endif /* __arm64__ */

        /*
         * Check arguments for validity
         */
        if ((target_map == VM_MAP_NULL) ||
            (cur_protection & ~VM_PROT_ALL) ||
            (max_protection & ~VM_PROT_ALL) ||
            (inheritance > VM_INHERIT_LAST_VALID) ||
            initial_size == 0) {
                return KERN_INVALID_ARGUMENT;
        }

#if __arm64__
        if (fourk && VM_MAP_PAGE_MASK(target_map) < PAGE_MASK) {
                fourk = FALSE;
        }

        if (fourk) {
                map_addr = vm_map_trunc_page(*address,
                    FOURK_PAGE_MASK);
                map_size = vm_map_round_page(initial_size,
                    FOURK_PAGE_MASK);
        } else
#endif /* __arm64__ */
        {
                map_addr = vm_map_trunc_page(*address,
                    VM_MAP_PAGE_MASK(target_map));
                map_size = vm_map_round_page(initial_size,
                    VM_MAP_PAGE_MASK(target_map));
        }
        size = vm_object_round_page(initial_size);

        object = memory_object_control_to_vm_object(control);

        if (object == VM_OBJECT_NULL) {
                return KERN_INVALID_OBJECT;
        }

        if (object == kernel_object) {
                printf("Warning: Attempt to map kernel object"
                    " by a non-private kernel entity\n");
                return KERN_INVALID_OBJECT;
        }

        vm_object_lock(object);
        object->ref_count++;
        vm_object_res_reference(object);

        /*
         * For "named" VM objects, let the pager know that the
         * memory object is being mapped.  Some pagers need to keep
         * track of this, to know when they can reclaim the memory
         * object, for example.
         * VM calls memory_object_map() for each mapping (specifying
         * the protection of each mapping) and calls
         * memory_object_last_unmap() when all the mappings are gone.
         */
        pager_prot = max_protection;
        if (copy) {
                pager_prot &= ~VM_PROT_WRITE;
        }
        pager = object->pager;
        if (object->named &&
            pager != MEMORY_OBJECT_NULL &&
            object->copy_strategy != MEMORY_OBJECT_COPY_NONE) {
                assert(object->pager_ready);
                vm_object_mapping_wait(object, THREAD_UNINT);
                vm_object_mapping_begin(object);
                vm_object_unlock(object);

                kr = memory_object_map(pager, pager_prot);
                assert(kr == KERN_SUCCESS);

                vm_object_lock(object);
                vm_object_mapping_end(object);
        }
        vm_object_unlock(object);

        /*
         *      Perform the copy if requested
         */

        if (copy) {
                vm_object_t             new_object;
                vm_object_offset_t      new_offset;

                result = vm_object_copy_strategically(object, offset, size,
                    &new_object, &new_offset,
                    &copy);


                if (result == KERN_MEMORY_RESTART_COPY) {
                        boolean_t success;
                        boolean_t src_needs_copy;

                        /*
                         * XXX
                         * We currently ignore src_needs_copy.
                         * This really is the issue of how to make
                         * MEMORY_OBJECT_COPY_SYMMETRIC safe for
                         * non-kernel users to use. Solution forthcoming.
                         * In the meantime, since we don't allow non-kernel
                         * memory managers to specify symmetric copy,
                         * we won't run into problems here.
                         */
                        new_object = object;
                        new_offset = offset;
                        success = vm_object_copy_quickly(&new_object,
                            new_offset, size,
                            &src_needs_copy,
                            &copy);
                        assert(success);
                        result = KERN_SUCCESS;
                }
                /*
                 *      Throw away the reference to the
                 *      original object, as it won't be mapped.
                 */

                vm_object_deallocate(object);

                if (result != KERN_SUCCESS) {
                        return result;
                }

                object = new_object;
                offset = new_offset;
        }

#if __arm64__
        if (fourk) {
                result = vm_map_enter_fourk(target_map,
                    &map_addr,
                    map_size,
                    (vm_map_offset_t)mask,
                    flags,
                    vmk_flags,
                    tag,
                    object, offset,
                    copy,
                    cur_protection, max_protection,
                    inheritance);
        } else
#endif /* __arm64__ */
        {
                result = vm_map_enter(target_map,
                    &map_addr, map_size,
                    (vm_map_offset_t)mask,
                    flags,
                    vmk_flags,
                    tag,
                    object, offset,
                    copy,
                    cur_protection, max_protection,
                    inheritance);
        }
        if (result != KERN_SUCCESS) {
                vm_object_deallocate(object);
        }
        *address = map_addr;

        return result;
}


#if     VM_CPM

#ifdef MACH_ASSERT
extern pmap_paddr_t     avail_start, avail_end;
#endif

/*
 *      Allocate memory in the specified map, with the caveat that
 *      the memory is physically contiguous.  This call may fail
 *      if the system can't find sufficient contiguous memory.
 *      This call may cause or lead to heart-stopping amounts of
 *      paging activity.
 *
 *      Memory obtained from this call should be freed in the
 *      normal way, viz., via vm_deallocate.
 */
kern_return_t
vm_map_enter_cpm(
        vm_map_t                map,
        vm_map_offset_t *addr,
        vm_map_size_t           size,
        int                     flags)
{
        vm_object_t             cpm_obj;
        pmap_t                  pmap;
        vm_page_t               m, pages;
        kern_return_t           kr;
        vm_map_offset_t         va, start, end, offset;
#if     MACH_ASSERT
        vm_map_offset_t         prev_addr = 0;
#endif  /* MACH_ASSERT */

        boolean_t               anywhere = ((VM_FLAGS_ANYWHERE & flags) != 0);
        vm_tag_t tag;

        if (VM_MAP_PAGE_SHIFT(map) != PAGE_SHIFT) {
                /* XXX TODO4K do we need to support this? */
                *addr = 0;
                return KERN_NOT_SUPPORTED;
        }

        VM_GET_FLAGS_ALIAS(flags, tag);

        if (size == 0) {
                *addr = 0;
                return KERN_SUCCESS;
        }
        if (anywhere) {
                *addr = vm_map_min(map);
        } else {
                *addr = vm_map_trunc_page(*addr,
                    VM_MAP_PAGE_MASK(map));
        }
        size = vm_map_round_page(size,
            VM_MAP_PAGE_MASK(map));

        /*
         * LP64todo - cpm_allocate should probably allow
         * allocations of >4GB, but not with the current
         * algorithm, so just cast down the size for now.
         */
        if (size > VM_MAX_ADDRESS) {
                return KERN_RESOURCE_SHORTAGE;
        }
        if ((kr = cpm_allocate(CAST_DOWN(vm_size_t, size),
            &pages, 0, 0, TRUE, flags)) != KERN_SUCCESS) {
                return kr;
        }

        cpm_obj = vm_object_allocate((vm_object_size_t)size);
        assert(cpm_obj != VM_OBJECT_NULL);
        assert(cpm_obj->internal);
        assert(cpm_obj->vo_size == (vm_object_size_t)size);
        assert(cpm_obj->can_persist == FALSE);
        assert(cpm_obj->pager_created == FALSE);
        assert(cpm_obj->pageout == FALSE);
        assert(cpm_obj->shadow == VM_OBJECT_NULL);

        /*
         *      Insert pages into object.
         */

        vm_object_lock(cpm_obj);
        for (offset = 0; offset < size; offset += PAGE_SIZE) {
                m = pages;
                pages = NEXT_PAGE(m);
                *(NEXT_PAGE_PTR(m)) = VM_PAGE_NULL;

                assert(!m->vmp_gobbled);
                assert(!m->vmp_wanted);
                assert(!m->vmp_pageout);
                assert(!m->vmp_tabled);
                assert(VM_PAGE_WIRED(m));
                assert(m->vmp_busy);
                assert(VM_PAGE_GET_PHYS_PAGE(m) >= (avail_start >> PAGE_SHIFT) && VM_PAGE_GET_PHYS_PAGE(m) <= (avail_end >> PAGE_SHIFT));

                m->vmp_busy = FALSE;
                vm_page_insert(m, cpm_obj, offset);
        }
        assert(cpm_obj->resident_page_count == size / PAGE_SIZE);
        vm_object_unlock(cpm_obj);

        /*
         *      Hang onto a reference on the object in case a
         *      multi-threaded application for some reason decides
         *      to deallocate the portion of the address space into
         *      which we will insert this object.
         *
         *      Unfortunately, we must insert the object now before
         *      we can talk to the pmap module about which addresses
         *      must be wired down.  Hence, the race with a multi-
         *      threaded app.
         */
        vm_object_reference(cpm_obj);

        /*
         *      Insert object into map.
         */

        kr = vm_map_enter(
                map,
                addr,
                size,
                (vm_map_offset_t)0,
                flags,
                VM_MAP_KERNEL_FLAGS_NONE,
                cpm_obj,
                (vm_object_offset_t)0,
                FALSE,
                VM_PROT_ALL,
                VM_PROT_ALL,
                VM_INHERIT_DEFAULT);

        if (kr != KERN_SUCCESS) {
                /*
                 *      A CPM object doesn't have can_persist set,
                 *      so all we have to do is deallocate it to
                 *      free up these pages.
                 */
                assert(cpm_obj->pager_created == FALSE);
                assert(cpm_obj->can_persist == FALSE);
                assert(cpm_obj->pageout == FALSE);
                assert(cpm_obj->shadow == VM_OBJECT_NULL);
                vm_object_deallocate(cpm_obj); /* kill acquired ref */
                vm_object_deallocate(cpm_obj); /* kill creation ref */
        }

        /*
         *      Inform the physical mapping system that the
         *      range of addresses may not fault, so that
         *      page tables and such can be locked down as well.
         */
        start = *addr;
        end = start + size;
        pmap = vm_map_pmap(map);
        pmap_pageable(pmap, start, end, FALSE);

        /*
         *      Enter each page into the pmap, to avoid faults.
         *      Note that this loop could be coded more efficiently,
         *      if the need arose, rather than looking up each page
         *      again.
         */
        for (offset = 0, va = start; offset < size;
            va += PAGE_SIZE, offset += PAGE_SIZE) {
                int type_of_fault;

                vm_object_lock(cpm_obj);
                m = vm_page_lookup(cpm_obj, (vm_object_offset_t)offset);
                assert(m != VM_PAGE_NULL);

                vm_page_zero_fill(m);

                type_of_fault = DBG_ZERO_FILL_FAULT;

                vm_fault_enter(m, pmap, va,
                    PAGE_SIZE, 0,
                    VM_PROT_ALL, VM_PROT_WRITE,
                    VM_PAGE_WIRED(m),
                    FALSE,                             /* change_wiring */
                    VM_KERN_MEMORY_NONE,                             /* tag - not wiring */
                    FALSE,                             /* no_cache */
                    FALSE,                             /* cs_bypass */
                    0,                                 /* user_tag */
                    0,                             /* pmap_options */
                    NULL,                              /* need_retry */
                    &type_of_fault);

                vm_object_unlock(cpm_obj);
        }

#if     MACH_ASSERT
        /*
         *      Verify ordering in address space.
         */
        for (offset = 0; offset < size; offset += PAGE_SIZE) {
                vm_object_lock(cpm_obj);
                m = vm_page_lookup(cpm_obj, (vm_object_offset_t)offset);
                vm_object_unlock(cpm_obj);
                if (m == VM_PAGE_NULL) {
                        panic("vm_allocate_cpm:  obj %p off 0x%llx no page",
                            cpm_obj, (uint64_t)offset);
                }
                assert(m->vmp_tabled);
                assert(!m->vmp_busy);
                assert(!m->vmp_wanted);
                assert(!m->vmp_fictitious);
                assert(!m->vmp_private);
                assert(!m->vmp_absent);
                assert(!m->vmp_error);
                assert(!m->vmp_cleaning);
                assert(!m->vmp_laundry);
                assert(!m->vmp_precious);
                assert(!m->vmp_clustered);
                if (offset != 0) {
                        if (VM_PAGE_GET_PHYS_PAGE(m) != prev_addr + 1) {
                                printf("start 0x%llx end 0x%llx va 0x%llx\n",
                                    (uint64_t)start, (uint64_t)end, (uint64_t)va);
                                printf("obj %p off 0x%llx\n", cpm_obj, (uint64_t)offset);
                                printf("m %p prev_address 0x%llx\n", m, (uint64_t)prev_addr);
                                panic("vm_allocate_cpm:  pages not contig!");
                        }
                }
                prev_addr = VM_PAGE_GET_PHYS_PAGE(m);
        }
#endif  /* MACH_ASSERT */

        vm_object_deallocate(cpm_obj); /* kill extra ref */

        return kr;
}


#else   /* VM_CPM */

/*
 *      Interface is defined in all cases, but unless the kernel
 *      is built explicitly for this option, the interface does
 *      nothing.
 */

kern_return_t
vm_map_enter_cpm(
        __unused vm_map_t       map,
        __unused vm_map_offset_t        *addr,
        __unused vm_map_size_t  size,
        __unused int            flags)
{
        return KERN_FAILURE;
}
#endif /* VM_CPM */

/* Not used without nested pmaps */
#ifndef NO_NESTED_PMAP
/*
 * Clip and unnest a portion of a nested submap mapping.
 */


static void
vm_map_clip_unnest(
        vm_map_t        map,
        vm_map_entry_t  entry,
        vm_map_offset_t start_unnest,
        vm_map_offset_t end_unnest)
{
        vm_map_offset_t old_start_unnest = start_unnest;
        vm_map_offset_t old_end_unnest = end_unnest;

        assert(entry->is_sub_map);
        assert(VME_SUBMAP(entry) != NULL);
        assert(entry->use_pmap);

        /*
         * Query the platform for the optimal unnest range.
         * DRK: There's some duplication of effort here, since
         * callers may have adjusted the range to some extent. This
         * routine was introduced to support 1GiB subtree nesting
         * for x86 platforms, which can also nest on 2MiB boundaries
         * depending on size/alignment.
         */
        if (pmap_adjust_unnest_parameters(map->pmap, &start_unnest, &end_unnest)) {
                assert(VME_SUBMAP(entry)->is_nested_map);
                assert(!VME_SUBMAP(entry)->disable_vmentry_reuse);
                log_unnest_badness(map,
                    old_start_unnest,
                    old_end_unnest,
                    VME_SUBMAP(entry)->is_nested_map,
                    (entry->vme_start +
                    VME_SUBMAP(entry)->lowest_unnestable_start -
                    VME_OFFSET(entry)));
        }

        if (entry->vme_start > start_unnest ||
            entry->vme_end < end_unnest) {
                panic("vm_map_clip_unnest(0x%llx,0x%llx): "
                    "bad nested entry: start=0x%llx end=0x%llx\n",
                    (long long)start_unnest, (long long)end_unnest,
                    (long long)entry->vme_start, (long long)entry->vme_end);
        }

        if (start_unnest > entry->vme_start) {
                _vm_map_clip_start(&map->hdr,
                    entry,
                    start_unnest);
                if (map->holelistenabled) {
                        vm_map_store_update_first_free(map, NULL, FALSE);
                } else {
                        vm_map_store_update_first_free(map, map->first_free, FALSE);
                }
        }
        if (entry->vme_end > end_unnest) {
                _vm_map_clip_end(&map->hdr,
                    entry,
                    end_unnest);
                if (map->holelistenabled) {
                        vm_map_store_update_first_free(map, NULL, FALSE);
                } else {
                        vm_map_store_update_first_free(map, map->first_free, FALSE);
                }
        }

        pmap_unnest(map->pmap,
            entry->vme_start,
            entry->vme_end - entry->vme_start);
        if ((map->mapped_in_other_pmaps) && os_ref_get_count(&map->map_refcnt) != 0) {
                /* clean up parent map/maps */
                vm_map_submap_pmap_clean(
                        map, entry->vme_start,
                        entry->vme_end,
                        VME_SUBMAP(entry),
                        VME_OFFSET(entry));
        }
        entry->use_pmap = FALSE;
        if ((map->pmap != kernel_pmap) &&
            (VME_ALIAS(entry) == VM_MEMORY_SHARED_PMAP)) {
                VME_ALIAS_SET(entry, VM_MEMORY_UNSHARED_PMAP);
        }
}
#endif  /* NO_NESTED_PMAP */

/*
 *      vm_map_clip_start:      [ internal use only ]
 *
 *      Asserts that the given entry begins at or after
 *      the specified address; if necessary,
 *      it splits the entry into two.
 */
void
vm_map_clip_start(
        vm_map_t        map,
        vm_map_entry_t  entry,
        vm_map_offset_t startaddr)
{
#ifndef NO_NESTED_PMAP
        if (entry->is_sub_map &&
            entry->use_pmap &&
            startaddr >= entry->vme_start) {
                vm_map_offset_t start_unnest, end_unnest;

                /*
                 * Make sure "startaddr" is no longer in a nested range
                 * before we clip.  Unnest only the minimum range the platform
                 * can handle.
                 * vm_map_clip_unnest may perform additional adjustments to
                 * the unnest range.
                 */
                start_unnest = startaddr & ~(pmap_shared_region_size_min(map->pmap) - 1);
                end_unnest = start_unnest + pmap_shared_region_size_min(map->pmap);
                vm_map_clip_unnest(map, entry, start_unnest, end_unnest);
        }
#endif /* NO_NESTED_PMAP */
        if (startaddr > entry->vme_start) {
                if (VME_OBJECT(entry) &&
                    !entry->is_sub_map &&
                    VME_OBJECT(entry)->phys_contiguous) {
                        pmap_remove(map->pmap,
                            (addr64_t)(entry->vme_start),
                            (addr64_t)(entry->vme_end));
                }
                if (entry->vme_atomic) {
                        panic("Attempting to clip an atomic VM entry! (map: %p, entry: %p)\n", map, entry);
                }

                DTRACE_VM5(
                        vm_map_clip_start,
                        vm_map_t, map,
                        vm_map_offset_t, entry->vme_start,
                        vm_map_offset_t, entry->vme_end,
                        vm_map_offset_t, startaddr,
                        int, VME_ALIAS(entry));

                _vm_map_clip_start(&map->hdr, entry, startaddr);
                if (map->holelistenabled) {
                        vm_map_store_update_first_free(map, NULL, FALSE);
                } else {
                        vm_map_store_update_first_free(map, map->first_free, FALSE);
                }
        }
}


#define vm_map_copy_clip_start(copy, entry, startaddr) \
        MACRO_BEGIN \
        if ((startaddr) > (entry)->vme_start) \
                _vm_map_clip_start(&(copy)->cpy_hdr,(entry),(startaddr)); \
        MACRO_END

/*
 *      This routine is called only when it is known that
 *      the entry must be split.
 */
static void
_vm_map_clip_start(
        struct vm_map_header    *map_header,
        vm_map_entry_t          entry,
        vm_map_offset_t         start)
{
        vm_map_entry_t  new_entry;

        /*
         *      Split off the front portion --
         *      note that we must insert the new
         *      entry BEFORE this one, so that
         *      this entry has the specified starting
         *      address.
         */

        if (entry->map_aligned) {
                assert(VM_MAP_PAGE_ALIGNED(start,
                    VM_MAP_HDR_PAGE_MASK(map_header)));
        }

        new_entry = _vm_map_entry_create(map_header, !map_header->entries_pageable);
        vm_map_entry_copy_full(new_entry, entry);

        new_entry->vme_end = start;
        assert(new_entry->vme_start < new_entry->vme_end);
        VME_OFFSET_SET(entry, VME_OFFSET(entry) + (start - entry->vme_start));
        assert(start < entry->vme_end);
        entry->vme_start = start;

        _vm_map_store_entry_link(map_header, entry->vme_prev, new_entry);

        if (entry->is_sub_map) {
                vm_map_reference(VME_SUBMAP(new_entry));
        } else {
                vm_object_reference(VME_OBJECT(new_entry));
        }
}


/*
 *      vm_map_clip_end:        [ internal use only ]
 *
 *      Asserts that the given entry ends at or before
 *      the specified address; if necessary,
 *      it splits the entry into two.
 */
void
vm_map_clip_end(
        vm_map_t        map,
        vm_map_entry_t  entry,
        vm_map_offset_t endaddr)
{
        if (endaddr > entry->vme_end) {
                /*
                 * Within the scope of this clipping, limit "endaddr" to
                 * the end of this map entry...
                 */
                endaddr = entry->vme_end;
        }
#ifndef NO_NESTED_PMAP
        if (entry->is_sub_map && entry->use_pmap) {
                vm_map_offset_t start_unnest, end_unnest;

                /*
                 * Make sure the range between the start of this entry and
                 * the new "endaddr" is no longer nested before we clip.
                 * Unnest only the minimum range the platform can handle.
                 * vm_map_clip_unnest may perform additional adjustments to
                 * the unnest range.
                 */
                start_unnest = entry->vme_start;
                end_unnest =
                    (endaddr + pmap_shared_region_size_min(map->pmap) - 1) &
                    ~(pmap_shared_region_size_min(map->pmap) - 1);
                vm_map_clip_unnest(map, entry, start_unnest, end_unnest);
        }
#endif /* NO_NESTED_PMAP */
        if (endaddr < entry->vme_end) {
                if (VME_OBJECT(entry) &&
                    !entry->is_sub_map &&
                    VME_OBJECT(entry)->phys_contiguous) {
                        pmap_remove(map->pmap,
                            (addr64_t)(entry->vme_start),
                            (addr64_t)(entry->vme_end));
                }
                if (entry->vme_atomic) {
                        panic("Attempting to clip an atomic VM entry! (map: %p, entry: %p)\n", map, entry);
                }
                DTRACE_VM5(
                        vm_map_clip_end,
                        vm_map_t, map,
                        vm_map_offset_t, entry->vme_start,
                        vm_map_offset_t, entry->vme_end,
                        vm_map_offset_t, endaddr,
                        int, VME_ALIAS(entry));

                _vm_map_clip_end(&map->hdr, entry, endaddr);
                if (map->holelistenabled) {
                        vm_map_store_update_first_free(map, NULL, FALSE);
                } else {
                        vm_map_store_update_first_free(map, map->first_free, FALSE);
                }
        }
}


#define vm_map_copy_clip_end(copy, entry, endaddr) \
        MACRO_BEGIN \
        if ((endaddr) < (entry)->vme_end) \
                _vm_map_clip_end(&(copy)->cpy_hdr,(entry),(endaddr)); \
        MACRO_END

/*
 *      This routine is called only when it is known that
 *      the entry must be split.
 */
static void
_vm_map_clip_end(
        struct vm_map_header    *map_header,
        vm_map_entry_t          entry,
        vm_map_offset_t         end)
{
        vm_map_entry_t  new_entry;

        /*
         *      Create a new entry and insert it
         *      AFTER the specified entry
         */

        if (entry->map_aligned) {
                assert(VM_MAP_PAGE_ALIGNED(end,
                    VM_MAP_HDR_PAGE_MASK(map_header)));
        }

        new_entry = _vm_map_entry_create(map_header, !map_header->entries_pageable);
        vm_map_entry_copy_full(new_entry, entry);

        assert(entry->vme_start < end);
        new_entry->vme_start = entry->vme_end = end;
        VME_OFFSET_SET(new_entry,
            VME_OFFSET(new_entry) + (end - entry->vme_start));
        assert(new_entry->vme_start < new_entry->vme_end);

        _vm_map_store_entry_link(map_header, entry, new_entry);

        if (entry->is_sub_map) {
                vm_map_reference(VME_SUBMAP(new_entry));
        } else {
                vm_object_reference(VME_OBJECT(new_entry));
        }
}


/*
 *      VM_MAP_RANGE_CHECK:     [ internal use only ]
 *
 *      Asserts that the starting and ending region
 *      addresses fall within the valid range of the map.
 */
#define VM_MAP_RANGE_CHECK(map, start, end)     \
        MACRO_BEGIN                             \
        if (start < vm_map_min(map))            \
                start = vm_map_min(map);        \
        if (end > vm_map_max(map))              \
                end = vm_map_max(map);          \
        if (start > end)                        \
                start = end;                    \
        MACRO_END

/*
 *      vm_map_range_check:     [ internal use only ]
 *
 *      Check that the region defined by the specified start and
 *      end addresses are wholly contained within a single map
 *      entry or set of adjacent map entries of the spacified map,
 *      i.e. the specified region contains no unmapped space.
 *      If any or all of the region is unmapped, FALSE is returned.
 *      Otherwise, TRUE is returned and if the output argument 'entry'
 *      is not NULL it points to the map entry containing the start
 *      of the region.
 *
 *      The map is locked for reading on entry and is left locked.
 */
static boolean_t
vm_map_range_check(
        vm_map_t                map,
        vm_map_offset_t         start,
        vm_map_offset_t         end,
        vm_map_entry_t          *entry)
{
        vm_map_entry_t          cur;
        vm_map_offset_t         prev;

        /*
         *      Basic sanity checks first
         */
        if (start < vm_map_min(map) || end > vm_map_max(map) || start > end) {
                return FALSE;
        }

        /*
         *      Check first if the region starts within a valid
         *      mapping for the map.
         */
        if (!vm_map_lookup_entry(map, start, &cur)) {
                return FALSE;
        }

        /*
         *      Optimize for the case that the region is contained
         *      in a single map entry.
         */
        if (entry != (vm_map_entry_t *) NULL) {
                *entry = cur;
        }
        if (end <= cur->vme_end) {
                return TRUE;
        }

        /*
         *      If the region is not wholly contained within a
         *      single entry, walk the entries looking for holes.
         */
        prev = cur->vme_end;
        cur = cur->vme_next;
        while ((cur != vm_map_to_entry(map)) && (prev == cur->vme_start)) {
                if (end <= cur->vme_end) {
                        return TRUE;
                }
                prev = cur->vme_end;
                cur = cur->vme_next;
        }
        return FALSE;
}

/*
 *      vm_map_submap:          [ kernel use only ]
 *
 *      Mark the given range as handled by a subordinate map.
 *
 *      This range must have been created with vm_map_find using
 *      the vm_submap_object, and no other operations may have been
 *      performed on this range prior to calling vm_map_submap.
 *
 *      Only a limited number of operations can be performed
 *      within this rage after calling vm_map_submap:
 *              vm_fault
 *      [Don't try vm_map_copyin!]
 *
 *      To remove a submapping, one must first remove the
 *      range from the superior map, and then destroy the
 *      submap (if desired).  [Better yet, don't try it.]
 */
kern_return_t
vm_map_submap(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end,
        vm_map_t        submap,
        vm_map_offset_t offset,
#ifdef NO_NESTED_PMAP
        __unused
#endif  /* NO_NESTED_PMAP */
        boolean_t       use_pmap)
{
        vm_map_entry_t          entry;
        kern_return_t           result = KERN_INVALID_ARGUMENT;
        vm_object_t             object;

        vm_map_lock(map);

        if (!vm_map_lookup_entry(map, start, &entry)) {
                entry = entry->vme_next;
        }

        if (entry == vm_map_to_entry(map) ||
            entry->is_sub_map) {
                vm_map_unlock(map);
                return KERN_INVALID_ARGUMENT;
        }

        vm_map_clip_start(map, entry, start);
        vm_map_clip_end(map, entry, end);

        if ((entry->vme_start == start) && (entry->vme_end == end) &&
            (!entry->is_sub_map) &&
            ((object = VME_OBJECT(entry)) == vm_submap_object) &&
            (object->resident_page_count == 0) &&
            (object->copy == VM_OBJECT_NULL) &&
            (object->shadow == VM_OBJECT_NULL) &&
            (!object->pager_created)) {
                VME_OFFSET_SET(entry, (vm_object_offset_t)offset);
                VME_OBJECT_SET(entry, VM_OBJECT_NULL);
                vm_object_deallocate(object);
                entry->is_sub_map = TRUE;
                entry->use_pmap = FALSE;
                VME_SUBMAP_SET(entry, submap);
                vm_map_reference(submap);
                if (submap->mapped_in_other_pmaps == FALSE &&
                    vm_map_pmap(submap) != PMAP_NULL &&
                    vm_map_pmap(submap) != vm_map_pmap(map)) {
                        /*
                         * This submap is being mapped in a map
                         * that uses a different pmap.
                         * Set its "mapped_in_other_pmaps" flag
                         * to indicate that we now need to
                         * remove mappings from all pmaps rather
                         * than just the submap's pmap.
                         */
                        submap->mapped_in_other_pmaps = TRUE;
                }

#ifndef NO_NESTED_PMAP
                if (use_pmap) {
                        /* nest if platform code will allow */
                        if (submap->pmap == NULL) {
                                ledger_t ledger = map->pmap->ledger;
                                submap->pmap = pmap_create_options(ledger,
                                    (vm_map_size_t) 0, 0);
                                if (submap->pmap == PMAP_NULL) {
                                        vm_map_unlock(map);
                                        return KERN_NO_SPACE;
                                }
#if     defined(__arm__) || defined(__arm64__)
                                pmap_set_nested(submap->pmap);
#endif
                        }
                        result = pmap_nest(map->pmap,
                            (VME_SUBMAP(entry))->pmap,
                            (addr64_t)start,
                            (uint64_t)(end - start));
                        if (result) {
                                panic("vm_map_submap: pmap_nest failed, rc = %08X\n", result);
                        }
                        entry->use_pmap = TRUE;
                }
#else   /* NO_NESTED_PMAP */
                pmap_remove(map->pmap, (addr64_t)start, (addr64_t)end);
#endif  /* NO_NESTED_PMAP */
                result = KERN_SUCCESS;
        }
        vm_map_unlock(map);

        return result;
}

/*
 *      vm_map_protect:
 *
 *      Sets the protection of the specified address
 *      region in the target map.  If "set_max" is
 *      specified, the maximum protection is to be set;
 *      otherwise, only the current protection is affected.
 */
kern_return_t
vm_map_protect(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end,
        vm_prot_t       new_prot,
        boolean_t       set_max)
{
        vm_map_entry_t                  current;
        vm_map_offset_t                 prev;
        vm_map_entry_t                  entry;
        vm_prot_t                       new_max;
        int                             pmap_options = 0;
        kern_return_t                   kr;

        if (new_prot & VM_PROT_COPY) {
                vm_map_offset_t         new_start;
                vm_prot_t               cur_prot, max_prot;
                vm_map_kernel_flags_t   kflags;

                /* LP64todo - see below */
                if (start >= map->max_offset) {
                        return KERN_INVALID_ADDRESS;
                }

                if ((new_prot & VM_PROT_EXECUTE) &&
                    map->pmap != kernel_pmap &&
                    (vm_map_cs_enforcement(map)
#if XNU_TARGET_OS_OSX && __arm64__
                    || !VM_MAP_IS_EXOTIC(map)
#endif /* XNU_TARGET_OS_OSX && __arm64__ */
                    ) &&
                    VM_MAP_POLICY_WX_FAIL(map)) {
                        DTRACE_VM3(cs_wx,
                            uint64_t, (uint64_t) start,
                            uint64_t, (uint64_t) end,
                            vm_prot_t, new_prot);
                        printf("CODE SIGNING: %d[%s] %s can't have both write and exec at the same time\n",
                            proc_selfpid(),
                            (current_task()->bsd_info
                            ? proc_name_address(current_task()->bsd_info)
                            : "?"),
                            __FUNCTION__);
                        return KERN_PROTECTION_FAILURE;
                }

                /*
                 * Let vm_map_remap_extract() know that it will need to:
                 * + make a copy of the mapping
                 * + add VM_PROT_WRITE to the max protections
                 * + remove any protections that are no longer allowed from the
                 *   max protections (to avoid any WRITE/EXECUTE conflict, for
                 *   example).
                 * Note that "max_prot" is an IN/OUT parameter only for this
                 * specific (VM_PROT_COPY) case.  It's usually an OUT parameter
                 * only.
                 */
                max_prot = new_prot & VM_PROT_ALL;
                kflags = VM_MAP_KERNEL_FLAGS_NONE;
                kflags.vmkf_remap_prot_copy = TRUE;
                kflags.vmkf_overwrite_immutable = TRUE;
                new_start = start;
                kr = vm_map_remap(map,
                    &new_start,
                    end - start,
                    0,               /* mask */
                    VM_FLAGS_FIXED | VM_FLAGS_OVERWRITE,
                    kflags,
                    0,
                    map,
                    start,
                    TRUE,               /* copy-on-write remapping! */
                    &cur_prot,
                    &max_prot,
                    VM_INHERIT_DEFAULT);
                if (kr != KERN_SUCCESS) {
                        return kr;
                }
                new_prot &= ~VM_PROT_COPY;
        }

        vm_map_lock(map);

        /* LP64todo - remove this check when vm_map_commpage64()
         * no longer has to stuff in a map_entry for the commpage
         * above the map's max_offset.
         */
        if (start >= map->max_offset) {
                vm_map_unlock(map);
                return KERN_INVALID_ADDRESS;
        }

        while (1) {
                /*
                 *      Lookup the entry.  If it doesn't start in a valid
                 *      entry, return an error.
                 */
                if (!vm_map_lookup_entry(map, start, &entry)) {
                        vm_map_unlock(map);
                        return KERN_INVALID_ADDRESS;
                }

                if (entry->superpage_size && (start & (SUPERPAGE_SIZE - 1))) { /* extend request to whole entry */
                        start = SUPERPAGE_ROUND_DOWN(start);
                        continue;
                }
                break;
        }
        if (entry->superpage_size) {
                end = SUPERPAGE_ROUND_UP(end);
        }

        /*
         *      Make a first pass to check for protection and address
         *      violations.
         */

        current = entry;
        prev = current->vme_start;
        while ((current != vm_map_to_entry(map)) &&
            (current->vme_start < end)) {
                /*
                 * If there is a hole, return an error.
                 */
                if (current->vme_start != prev) {
                        vm_map_unlock(map);
                        return KERN_INVALID_ADDRESS;
                }

                new_max = current->max_protection;
                if ((new_prot & new_max) != new_prot) {
                        vm_map_unlock(map);
                        return KERN_PROTECTION_FAILURE;
                }

                if ((new_prot & VM_PROT_WRITE) &&
                    (new_prot & VM_PROT_EXECUTE) &&
#if XNU_TARGET_OS_OSX
                    map->pmap != kernel_pmap &&
                    (vm_map_cs_enforcement(map)
#if __arm64__
                    || !VM_MAP_IS_EXOTIC(map)
#endif /* __arm64__ */
                    ) &&
#endif /* XNU_TARGET_OS_OSX */
                    !(current->used_for_jit)) {
                        DTRACE_VM3(cs_wx,
                            uint64_t, (uint64_t) current->vme_start,
                            uint64_t, (uint64_t) current->vme_end,
                            vm_prot_t, new_prot);
                        printf("CODE SIGNING: %d[%s] %s can't have both write and exec at the same time\n",
                            proc_selfpid(),
                            (current_task()->bsd_info
                            ? proc_name_address(current_task()->bsd_info)
                            : "?"),
                            __FUNCTION__);
                        new_prot &= ~VM_PROT_EXECUTE;
                        if (VM_MAP_POLICY_WX_FAIL(map)) {
                                vm_map_unlock(map);
                                return KERN_PROTECTION_FAILURE;
                        }
                }

                /*
                 * If the task has requested executable lockdown,
                 * deny both:
                 * - adding executable protections OR
                 * - adding write protections to an existing executable mapping.
                 */
                if (map->map_disallow_new_exec == TRUE) {
                        if ((new_prot & VM_PROT_EXECUTE) ||
                            ((current->protection & VM_PROT_EXECUTE) && (new_prot & VM_PROT_WRITE))) {
                                vm_map_unlock(map);
                                return KERN_PROTECTION_FAILURE;
                        }
                }

                prev = current->vme_end;
                current = current->vme_next;
        }

#if __arm64__
        if (end > prev &&
            end == vm_map_round_page(prev, VM_MAP_PAGE_MASK(map))) {
                vm_map_entry_t prev_entry;

                prev_entry = current->vme_prev;
                if (prev_entry != vm_map_to_entry(map) &&
                    !prev_entry->map_aligned &&
                    (vm_map_round_page(prev_entry->vme_end,
                    VM_MAP_PAGE_MASK(map))
                    == end)) {
                        /*
                         * The last entry in our range is not "map-aligned"
                         * but it would have reached all the way to "end"
                         * if it had been map-aligned, so this is not really
                         * a hole in the range and we can proceed.
                         */
                        prev = end;
                }
        }
#endif /* __arm64__ */

        if (end > prev) {
                vm_map_unlock(map);
                return KERN_INVALID_ADDRESS;
        }

        /*
         *      Go back and fix up protections.
         *      Clip to start here if the range starts within
         *      the entry.
         */

        current = entry;
        if (current != vm_map_to_entry(map)) {
                /* clip and unnest if necessary */
                vm_map_clip_start(map, current, start);
        }

        while ((current != vm_map_to_entry(map)) &&
            (current->vme_start < end)) {
                vm_prot_t       old_prot;

                vm_map_clip_end(map, current, end);

                if (current->is_sub_map) {
                        /* clipping did unnest if needed */
                        assert(!current->use_pmap);
                }

                old_prot = current->protection;

                if (set_max) {
                        current->max_protection = new_prot;
                        current->protection = new_prot & old_prot;
                } else {
                        current->protection = new_prot;
                }

                /*
                 *      Update physical map if necessary.
                 *      If the request is to turn off write protection,
                 *      we won't do it for real (in pmap). This is because
                 *      it would cause copy-on-write to fail.  We've already
                 *      set, the new protection in the map, so if a
                 *      write-protect fault occurred, it will be fixed up
                 *      properly, COW or not.
                 */
                if (current->protection != old_prot) {
                        /* Look one level in we support nested pmaps */
                        /* from mapped submaps which are direct entries */
                        /* in our map */

                        vm_prot_t prot;

                        prot = current->protection;
                        if (current->is_sub_map || (VME_OBJECT(current) == NULL) || (VME_OBJECT(current) != compressor_object)) {
                                prot &= ~VM_PROT_WRITE;
                        } else {
                                assert(!VME_OBJECT(current)->code_signed);
                                assert(VME_OBJECT(current)->copy_strategy == MEMORY_OBJECT_COPY_NONE);
                        }

                        if (override_nx(map, VME_ALIAS(current)) && prot) {
                                prot |= VM_PROT_EXECUTE;
                        }

#if DEVELOPMENT || DEBUG
                        if (!(old_prot & VM_PROT_EXECUTE) &&
                            (prot & VM_PROT_EXECUTE) &&
                            panic_on_unsigned_execute &&
                            (proc_selfcsflags() & CS_KILL)) {
                                panic("vm_map_protect(%p,0x%llx,0x%llx) old=0x%x new=0x%x - <rdar://23770418> code-signing bypass?\n", map, (uint64_t)current->vme_start, (uint64_t)current->vme_end, old_prot, prot);
                        }
#endif /* DEVELOPMENT || DEBUG */

                        if (pmap_has_prot_policy(map->pmap, current->translated_allow_execute, prot)) {
                                if (current->wired_count) {
                                        panic("vm_map_protect(%p,0x%llx,0x%llx) new=0x%x wired=%x\n",
                                            map, (uint64_t)current->vme_start, (uint64_t)current->vme_end, prot, current->wired_count);
                                }

                                /* If the pmap layer cares about this
                                 * protection type, force a fault for
                                 * each page so that vm_fault will
                                 * repopulate the page with the full
                                 * set of protections.
                                 */
                                /*
                                 * TODO: We don't seem to need this,
                                 * but this is due to an internal
                                 * implementation detail of
                                 * pmap_protect.  Do we want to rely
                                 * on this?
                                 */
                                prot = VM_PROT_NONE;
                        }

                        if (current->is_sub_map && current->use_pmap) {
                                pmap_protect(VME_SUBMAP(current)->pmap,
                                    current->vme_start,
                                    current->vme_end,
                                    prot);
                        } else {
                                if (prot & VM_PROT_WRITE) {
                                        if (VME_OBJECT(current) == compressor_object) {
                                                /*
                                                 * For write requests on the
                                                 * compressor, we wil ask the
                                                 * pmap layer to prevent us from
                                                 * taking a write fault when we
                                                 * attempt to access the mapping
                                                 * next.
                                                 */
                                                pmap_options |= PMAP_OPTIONS_PROTECT_IMMEDIATE;
                                        }
                                }

                                pmap_protect_options(map->pmap,
                                    current->vme_start,
                                    current->vme_end,
                                    prot,
                                    pmap_options,
                                    NULL);
                        }
                }
                current = current->vme_next;
        }

        current = entry;
        while ((current != vm_map_to_entry(map)) &&
            (current->vme_start <= end)) {
                vm_map_simplify_entry(map, current);
                current = current->vme_next;
        }

        vm_map_unlock(map);
        return KERN_SUCCESS;
}

/*
 *      vm_map_inherit:
 *
 *      Sets the inheritance of the specified address
 *      range in the target map.  Inheritance
 *      affects how the map will be shared with
 *      child maps at the time of vm_map_fork.
 */
kern_return_t
vm_map_inherit(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end,
        vm_inherit_t    new_inheritance)
{
        vm_map_entry_t  entry;
        vm_map_entry_t  temp_entry;

        vm_map_lock(map);

        VM_MAP_RANGE_CHECK(map, start, end);

        if (vm_map_lookup_entry(map, start, &temp_entry)) {
                entry = temp_entry;
        } else {
                temp_entry = temp_entry->vme_next;
                entry = temp_entry;
        }

        /* first check entire range for submaps which can't support the */
        /* given inheritance. */
        while ((entry != vm_map_to_entry(map)) && (entry->vme_start < end)) {
                if (entry->is_sub_map) {
                        if (new_inheritance == VM_INHERIT_COPY) {
                                vm_map_unlock(map);
                                return KERN_INVALID_ARGUMENT;
                        }
                }

                entry = entry->vme_next;
        }

        entry = temp_entry;
        if (entry != vm_map_to_entry(map)) {
                /* clip and unnest if necessary */
                vm_map_clip_start(map, entry, start);
        }

        while ((entry != vm_map_to_entry(map)) && (entry->vme_start < end)) {
                vm_map_clip_end(map, entry, end);
                if (entry->is_sub_map) {
                        /* clip did unnest if needed */
                        assert(!entry->use_pmap);
                }

                entry->inheritance = new_inheritance;

                entry = entry->vme_next;
        }

        vm_map_unlock(map);
        return KERN_SUCCESS;
}

/*
 * Update the accounting for the amount of wired memory in this map.  If the user has
 * exceeded the defined limits, then we fail.  Wiring on behalf of the kernel never fails.
 */

static kern_return_t
add_wire_counts(
        vm_map_t        map,
        vm_map_entry_t  entry,
        boolean_t       user_wire)
{
        vm_map_size_t   size;

        if (user_wire) {
                unsigned int total_wire_count =  vm_page_wire_count + vm_lopage_free_count;

                /*
                 * We're wiring memory at the request of the user.  Check if this is the first time the user is wiring
                 * this map entry.
                 */

                if (entry->user_wired_count == 0) {
                        size = entry->vme_end - entry->vme_start;

                        /*
                         * Since this is the first time the user is wiring this map entry, check to see if we're
                         * exceeding the user wire limits.  There is a per map limit which is the smaller of either
                         * the process's rlimit or the global vm_per_task_user_wire_limit which caps this value.  There is also
                         * a system-wide limit on the amount of memory all users can wire.  If the user is over either
                         * limit, then we fail.
                         */

                        if (size + map->user_wire_size > MIN(map->user_wire_limit, vm_per_task_user_wire_limit) ||
                            size + ptoa_64(total_wire_count) > vm_global_user_wire_limit) {
                                if (size + ptoa_64(total_wire_count) > vm_global_user_wire_limit) {
                                        os_atomic_inc(&vm_add_wire_count_over_global_limit, relaxed);
                                } else {
                                        os_atomic_inc(&vm_add_wire_count_over_user_limit, relaxed);
                                }
                                return KERN_RESOURCE_SHORTAGE;
                        }

                        /*
                         * The first time the user wires an entry, we also increment the wired_count and add this to
                         * the total that has been wired in the map.
                         */

                        if (entry->wired_count >= MAX_WIRE_COUNT) {
                                return KERN_FAILURE;
                        }

                        entry->wired_count++;
                        map->user_wire_size += size;
                }

                if (entry->user_wired_count >= MAX_WIRE_COUNT) {
                        return KERN_FAILURE;
                }

                entry->user_wired_count++;
        } else {
                /*
                 * The kernel's wiring the memory.  Just bump the count and continue.
                 */

                if (entry->wired_count >= MAX_WIRE_COUNT) {
                        panic("vm_map_wire: too many wirings");
                }

                entry->wired_count++;
        }

        return KERN_SUCCESS;
}

/*
 * Update the memory wiring accounting now that the given map entry is being unwired.
 */

static void
subtract_wire_counts(
        vm_map_t        map,
        vm_map_entry_t  entry,
        boolean_t       user_wire)
{
        if (user_wire) {
                /*
                 * We're unwiring memory at the request of the user.  See if we're removing the last user wire reference.
                 */

                if (entry->user_wired_count == 1) {
                        /*
                         * We're removing the last user wire reference.  Decrement the wired_count and the total
                         * user wired memory for this map.
                         */

                        assert(entry->wired_count >= 1);
                        entry->wired_count--;
                        map->user_wire_size -= entry->vme_end - entry->vme_start;
                }

                assert(entry->user_wired_count >= 1);
                entry->user_wired_count--;
        } else {
                /*
                 * The kernel is unwiring the memory.   Just update the count.
                 */

                assert(entry->wired_count >= 1);
                entry->wired_count--;
        }
}

int cs_executable_wire = 0;

/*
 *      vm_map_wire:
 *
 *      Sets the pageability of the specified address range in the
 *      target map as wired.  Regions specified as not pageable require
 *      locked-down physical memory and physical page maps.  The
 *      access_type variable indicates types of accesses that must not
 *      generate page faults.  This is checked against protection of
 *      memory being locked-down.
 *
 *      The map must not be locked, but a reference must remain to the
 *      map throughout the call.
 */
static kern_return_t
vm_map_wire_nested(
        vm_map_t                map,
        vm_map_offset_t         start,
        vm_map_offset_t         end,
        vm_prot_t               caller_prot,
        vm_tag_t                tag,
        boolean_t               user_wire,
        pmap_t                  map_pmap,
        vm_map_offset_t         pmap_addr,
        ppnum_t                 *physpage_p)
{
        vm_map_entry_t          entry;
        vm_prot_t               access_type;
        struct vm_map_entry     *first_entry, tmp_entry;
        vm_map_t                real_map;
        vm_map_offset_t         s, e;
        kern_return_t           rc;
        boolean_t               need_wakeup;
        boolean_t               main_map = FALSE;
        wait_interrupt_t        interruptible_state;
        thread_t                cur_thread;
        unsigned int            last_timestamp;
        vm_map_size_t           size;
        boolean_t               wire_and_extract;
        vm_prot_t               extra_prots;

        extra_prots = VM_PROT_COPY;
        extra_prots |= VM_PROT_COPY_FAIL_IF_EXECUTABLE;
#if XNU_TARGET_OS_OSX
        if (map->pmap == kernel_pmap ||
            !vm_map_cs_enforcement(map)) {
                extra_prots &= ~VM_PROT_COPY_FAIL_IF_EXECUTABLE;
        }
#endif /* XNU_TARGET_OS_OSX */

        access_type = (caller_prot & VM_PROT_ALL);

        wire_and_extract = FALSE;
        if (physpage_p != NULL) {
                /*
                 * The caller wants the physical page number of the
                 * wired page.  We return only one physical page number
                 * so this works for only one page at a time.
                 */
                if ((end - start) != PAGE_SIZE) {
                        return KERN_INVALID_ARGUMENT;
                }
                wire_and_extract = TRUE;
                *physpage_p = 0;
        }

        vm_map_lock(map);
        if (map_pmap == NULL) {
                main_map = TRUE;
        }
        last_timestamp = map->timestamp;

        VM_MAP_RANGE_CHECK(map, start, end);
        assert(VM_MAP_PAGE_ALIGNED(start, VM_MAP_PAGE_MASK(map)));
        assert(VM_MAP_PAGE_ALIGNED(end, VM_MAP_PAGE_MASK(map)));

        if (start == end) {
                /* We wired what the caller asked for, zero pages */
                vm_map_unlock(map);
                return KERN_SUCCESS;
        }

        need_wakeup = FALSE;
        cur_thread = current_thread();

        s = start;
        rc = KERN_SUCCESS;

        if (vm_map_lookup_entry(map, s, &first_entry)) {
                entry = first_entry;
                /*
                 * vm_map_clip_start will be done later.
                 * We don't want to unnest any nested submaps here !
                 */
        } else {
                /* Start address is not in map */
                rc = KERN_INVALID_ADDRESS;
                goto done;
        }

        while ((entry != vm_map_to_entry(map)) && (s < end)) {
                /*
                 * At this point, we have wired from "start" to "s".
                 * We still need to wire from "s" to "end".
                 *
                 * "entry" hasn't been clipped, so it could start before "s"
                 * and/or end after "end".
                 */

                /* "e" is how far we want to wire in this entry */
                e = entry->vme_end;
                if (e > end) {
                        e = end;
                }

                /*
                 * If another thread is wiring/unwiring this entry then
                 * block after informing other thread to wake us up.
                 */
                if (entry->in_transition) {
                        wait_result_t wait_result;

                        /*
                         * We have not clipped the entry.  Make sure that
                         * the start address is in range so that the lookup
                         * below will succeed.
                         * "s" is the current starting point: we've already
                         * wired from "start" to "s" and we still have
                         * to wire from "s" to "end".
                         */

                        entry->needs_wakeup = TRUE;

                        /*
                         * wake up anybody waiting on entries that we have
                         * already wired.
                         */
                        if (need_wakeup) {
                                vm_map_entry_wakeup(map);
                                need_wakeup = FALSE;
                        }
                        /*
                         * User wiring is interruptible
                         */
                        wait_result = vm_map_entry_wait(map,
                            (user_wire) ? THREAD_ABORTSAFE :
                            THREAD_UNINT);
                        if (user_wire && wait_result == THREAD_INTERRUPTED) {
                                /*
                                 * undo the wirings we have done so far
                                 * We do not clear the needs_wakeup flag,
                                 * because we cannot tell if we were the
                                 * only one waiting.
                                 */
                                rc = KERN_FAILURE;
                                goto done;
                        }

                        /*
                         * Cannot avoid a lookup here. reset timestamp.
                         */
                        last_timestamp = map->timestamp;

                        /*
                         * The entry could have been clipped, look it up again.
                         * Worse that can happen is, it may not exist anymore.
                         */
                        if (!vm_map_lookup_entry(map, s, &first_entry)) {
                                /*
                                 * User: undo everything upto the previous
                                 * entry.  let vm_map_unwire worry about
                                 * checking the validity of the range.
                                 */
                                rc = KERN_FAILURE;
                                goto done;
                        }
                        entry = first_entry;
                        continue;
                }

                if (entry->is_sub_map) {
                        vm_map_offset_t sub_start;
                        vm_map_offset_t sub_end;
                        vm_map_offset_t local_start;
                        vm_map_offset_t local_end;
                        pmap_t          pmap;

                        if (wire_and_extract) {
                                /*
                                 * Wiring would result in copy-on-write
                                 * which would not be compatible with
                                 * the sharing we have with the original
                                 * provider of this memory.
                                 */
                                rc = KERN_INVALID_ARGUMENT;
                                goto done;
                        }

                        vm_map_clip_start(map, entry, s);
                        vm_map_clip_end(map, entry, end);

                        sub_start = VME_OFFSET(entry);
                        sub_end = entry->vme_end;
                        sub_end += VME_OFFSET(entry) - entry->vme_start;

                        local_end = entry->vme_end;
                        if (map_pmap == NULL) {
                                vm_object_t             object;
                                vm_object_offset_t      offset;
                                vm_prot_t               prot;
                                boolean_t               wired;
                                vm_map_entry_t          local_entry;
                                vm_map_version_t         version;
                                vm_map_t                lookup_map;

                                if (entry->use_pmap) {
                                        pmap = VME_SUBMAP(entry)->pmap;
                                        /* ppc implementation requires that */
                                        /* submaps pmap address ranges line */
                                        /* up with parent map */
#ifdef notdef
                                        pmap_addr = sub_start;
#endif
                                        pmap_addr = s;
                                } else {
                                        pmap = map->pmap;
                                        pmap_addr = s;
                                }

                                if (entry->wired_count) {
                                        if ((rc = add_wire_counts(map, entry, user_wire)) != KERN_SUCCESS) {
                                                goto done;
                                        }

                                        /*
                                         * The map was not unlocked:
                                         * no need to goto re-lookup.
                                         * Just go directly to next entry.
                                         */
                                        entry = entry->vme_next;
                                        s = entry->vme_start;
                                        continue;
                                }

                                /* call vm_map_lookup_locked to */
                                /* cause any needs copy to be   */
                                /* evaluated */
                                local_start = entry->vme_start;
                                lookup_map = map;
                                vm_map_lock_write_to_read(map);
                                rc = vm_map_lookup_locked(
                                        &lookup_map, local_start,
                                        (access_type | extra_prots),
                                        OBJECT_LOCK_EXCLUSIVE,
                                        &version, &object,
                                        &offset, &prot, &wired,
                                        NULL,
                                        &real_map, NULL);
                                if (rc != KERN_SUCCESS) {
                                        vm_map_unlock_read(lookup_map);
                                        assert(map_pmap == NULL);
                                        vm_map_unwire(map, start,
                                            s, user_wire);
                                        return rc;
                                }
                                vm_object_unlock(object);
                                if (real_map != lookup_map) {
                                        vm_map_unlock(real_map);
                                }
                                vm_map_unlock_read(lookup_map);
                                vm_map_lock(map);

                                /* we unlocked, so must re-lookup */
                                if (!vm_map_lookup_entry(map,
                                    local_start,
                                    &local_entry)) {
                                        rc = KERN_FAILURE;
                                        goto done;
                                }

                                /*
                                 * entry could have been "simplified",
                                 * so re-clip
                                 */
                                entry = local_entry;
                                assert(s == local_start);
                                vm_map_clip_start(map, entry, s);
                                vm_map_clip_end(map, entry, end);
                                /* re-compute "e" */
                                e = entry->vme_end;
                                if (e > end) {
                                        e = end;
                                }

                                /* did we have a change of type? */
                                if (!entry->is_sub_map) {
                                        last_timestamp = map->timestamp;
                                        continue;
                                }
                        } else {
                                local_start = entry->vme_start;
                                pmap = map_pmap;
                        }

                        if ((rc = add_wire_counts(map, entry, user_wire)) != KERN_SUCCESS) {
                                goto done;
                        }

                        entry->in_transition = TRUE;

                        vm_map_unlock(map);
                        rc = vm_map_wire_nested(VME_SUBMAP(entry),
                            sub_start, sub_end,
                            caller_prot, tag,
                            user_wire, pmap, pmap_addr,
                            NULL);
                        vm_map_lock(map);

                        /*
                         * Find the entry again.  It could have been clipped
                         * after we unlocked the map.
                         */
                        if (!vm_map_lookup_entry(map, local_start,
                            &first_entry)) {
                                panic("vm_map_wire: re-lookup failed");
                        }
                        entry = first_entry;

                        assert(local_start == s);
                        /* re-compute "e" */
                        e = entry->vme_end;
                        if (e > end) {
                                e = end;
                        }

                        last_timestamp = map->timestamp;
                        while ((entry != vm_map_to_entry(map)) &&
                            (entry->vme_start < e)) {
                                assert(entry->in_transition);
                                entry->in_transition = FALSE;
                                if (entry->needs_wakeup) {
                                        entry->needs_wakeup = FALSE;
                                        need_wakeup = TRUE;
                                }
                                if (rc != KERN_SUCCESS) {/* from vm_*_wire */
                                        subtract_wire_counts(map, entry, user_wire);
                                }
                                entry = entry->vme_next;
                        }
                        if (rc != KERN_SUCCESS) {       /* from vm_*_wire */
                                goto done;
                        }

                        /* no need to relookup again */
                        s = entry->vme_start;
                        continue;
                }

                /*
                 * If this entry is already wired then increment
                 * the appropriate wire reference count.
                 */
                if (entry->wired_count) {
                        if ((entry->protection & access_type) != access_type) {
                                /* found a protection problem */

                                /*
                                 * XXX FBDP
                                 * We should always return an error
                                 * in this case but since we didn't
                                 * enforce it before, let's do
                                 * it only for the new "wire_and_extract"
                                 * code path for now...
                                 */
                                if (wire_and_extract) {
                                        rc = KERN_PROTECTION_FAILURE;
                                        goto done;
                                }
                        }

                        /*
                         * entry is already wired down, get our reference
                         * after clipping to our range.
                         */
                        vm_map_clip_start(map, entry, s);
                        vm_map_clip_end(map, entry, end);

                        if ((rc = add_wire_counts(map, entry, user_wire)) != KERN_SUCCESS) {
                                goto done;
                        }

                        if (wire_and_extract) {
                                vm_object_t             object;
                                vm_object_offset_t      offset;
                                vm_page_t               m;

                                /*
                                 * We don't have to "wire" the page again
                                 * bit we still have to "extract" its
                                 * physical page number, after some sanity
                                 * checks.
                                 */
                                assert((entry->vme_end - entry->vme_start)
                                    == PAGE_SIZE);
                                assert(!entry->needs_copy);
                                assert(!entry->is_sub_map);
                                assert(VME_OBJECT(entry));
                                if (((entry->vme_end - entry->vme_start)
                                    != PAGE_SIZE) ||
                                    entry->needs_copy ||
                                    entry->is_sub_map ||
                                    VME_OBJECT(entry) == VM_OBJECT_NULL) {
                                        rc = KERN_INVALID_ARGUMENT;
                                        goto done;
                                }

                                object = VME_OBJECT(entry);
                                offset = VME_OFFSET(entry);
                                /* need exclusive lock to update m->dirty */
                                if (entry->protection & VM_PROT_WRITE) {
                                        vm_object_lock(object);
                                } else {
                                        vm_object_lock_shared(object);
                                }
                                m = vm_page_lookup(object, offset);
                                assert(m != VM_PAGE_NULL);
                                assert(VM_PAGE_WIRED(m));
                                if (m != VM_PAGE_NULL && VM_PAGE_WIRED(m)) {
                                        *physpage_p = VM_PAGE_GET_PHYS_PAGE(m);
                                        if (entry->protection & VM_PROT_WRITE) {
                                                vm_object_lock_assert_exclusive(
                                                        object);
                                                m->vmp_dirty = TRUE;
                                        }
                                } else {
                                        /* not already wired !? */
                                        *physpage_p = 0;
                                }
                                vm_object_unlock(object);
                        }

                        /* map was not unlocked: no need to relookup */
                        entry = entry->vme_next;
                        s = entry->vme_start;
                        continue;
                }

                /*
                 * Unwired entry or wire request transmitted via submap
                 */

                /*
                 * Wiring would copy the pages to the shadow object.
                 * The shadow object would not be code-signed so
                 * attempting to execute code from these copied pages
                 * would trigger a code-signing violation.
                 */

                if ((entry->protection & VM_PROT_EXECUTE)
#if XNU_TARGET_OS_OSX
                    &&
                    map->pmap != kernel_pmap &&
                    (vm_map_cs_enforcement(map)
#if __arm64__
                    || !VM_MAP_IS_EXOTIC(map)
#endif /* __arm64__ */
                    )
#endif /* XNU_TARGET_OS_OSX */
                    ) {
#if MACH_ASSERT
                        printf("pid %d[%s] wiring executable range from "
                            "0x%llx to 0x%llx: rejected to preserve "
                            "code-signing\n",
                            proc_selfpid(),
                            (current_task()->bsd_info
                            ? proc_name_address(current_task()->bsd_info)
                            : "?"),
                            (uint64_t) entry->vme_start,
                            (uint64_t) entry->vme_end);
#endif /* MACH_ASSERT */
                        DTRACE_VM2(cs_executable_wire,
                            uint64_t, (uint64_t)entry->vme_start,
                            uint64_t, (uint64_t)entry->vme_end);
                        cs_executable_wire++;
                        rc = KERN_PROTECTION_FAILURE;
                        goto done;
                }

                /*
                 * Perform actions of vm_map_lookup that need the write
                 * lock on the map: create a shadow object for a
                 * copy-on-write region, or an object for a zero-fill
                 * region.
                 */
                size = entry->vme_end - entry->vme_start;
                /*
                 * If wiring a copy-on-write page, we need to copy it now
                 * even if we're only (currently) requesting read access.
                 * This is aggressive, but once it's wired we can't move it.
                 */
                if (entry->needs_copy) {
                        if (wire_and_extract) {
                                /*
                                 * We're supposed to share with the original
                                 * provider so should not be "needs_copy"
                                 */
                                rc = KERN_INVALID_ARGUMENT;
                                goto done;
                        }

                        VME_OBJECT_SHADOW(entry, size);
                        entry->needs_copy = FALSE;
                } else if (VME_OBJECT(entry) == VM_OBJECT_NULL) {
                        if (wire_and_extract) {
                                /*
                                 * We're supposed to share with the original
                                 * provider so should already have an object.
                                 */
                                rc = KERN_INVALID_ARGUMENT;
                                goto done;
                        }
                        VME_OBJECT_SET(entry, vm_object_allocate(size));
                        VME_OFFSET_SET(entry, (vm_object_offset_t)0);
                        assert(entry->use_pmap);
                }

                vm_map_clip_start(map, entry, s);
                vm_map_clip_end(map, entry, end);

                /* re-compute "e" */
                e = entry->vme_end;
                if (e > end) {
                        e = end;
                }

                /*
                 * Check for holes and protection mismatch.
                 * Holes: Next entry should be contiguous unless this
                 *        is the end of the region.
                 * Protection: Access requested must be allowed, unless
                 *      wiring is by protection class
                 */
                if ((entry->vme_end < end) &&
                    ((entry->vme_next == vm_map_to_entry(map)) ||
                    (entry->vme_next->vme_start > entry->vme_end))) {
                        /* found a hole */
                        rc = KERN_INVALID_ADDRESS;
                        goto done;
                }
                if ((entry->protection & access_type) != access_type) {
                        /* found a protection problem */
                        rc = KERN_PROTECTION_FAILURE;
                        goto done;
                }

                assert(entry->wired_count == 0 && entry->user_wired_count == 0);

                if ((rc = add_wire_counts(map, entry, user_wire)) != KERN_SUCCESS) {
                        goto done;
                }

                entry->in_transition = TRUE;

                /*
                 * This entry might get split once we unlock the map.
                 * In vm_fault_wire(), we need the current range as
                 * defined by this entry.  In order for this to work
                 * along with a simultaneous clip operation, we make a
                 * temporary copy of this entry and use that for the
                 * wiring.  Note that the underlying objects do not
                 * change during a clip.
                 */
                tmp_entry = *entry;

                /*
                 * The in_transition state guarentees that the entry
                 * (or entries for this range, if split occured) will be
                 * there when the map lock is acquired for the second time.
                 */
                vm_map_unlock(map);

                if (!user_wire && cur_thread != THREAD_NULL) {
                        interruptible_state = thread_interrupt_level(THREAD_UNINT);
                } else {
                        interruptible_state = THREAD_UNINT;
                }

                if (map_pmap) {
                        rc = vm_fault_wire(map,
                            &tmp_entry, caller_prot, tag, map_pmap, pmap_addr,
                            physpage_p);
                } else {
                        rc = vm_fault_wire(map,
                            &tmp_entry, caller_prot, tag, map->pmap,
                            tmp_entry.vme_start,
                            physpage_p);
                }

                if (!user_wire && cur_thread != THREAD_NULL) {
                        thread_interrupt_level(interruptible_state);
                }

                vm_map_lock(map);

                if (last_timestamp + 1 != map->timestamp) {
                        /*
                         * Find the entry again.  It could have been clipped
                         * after we unlocked the map.
                         */
                        if (!vm_map_lookup_entry(map, tmp_entry.vme_start,
                            &first_entry)) {
                                panic("vm_map_wire: re-lookup failed");
                        }

                        entry = first_entry;
                }

                last_timestamp = map->timestamp;

                while ((entry != vm_map_to_entry(map)) &&
                    (entry->vme_start < tmp_entry.vme_end)) {
                        assert(entry->in_transition);
                        entry->in_transition = FALSE;
                        if (entry->needs_wakeup) {
                                entry->needs_wakeup = FALSE;
                                need_wakeup = TRUE;
                        }
                        if (rc != KERN_SUCCESS) {       /* from vm_*_wire */
                                subtract_wire_counts(map, entry, user_wire);
                        }
                        entry = entry->vme_next;
                }

                if (rc != KERN_SUCCESS) {               /* from vm_*_wire */
                        goto done;
                }

                if ((entry != vm_map_to_entry(map)) && /* we still have entries in the map */
                    (tmp_entry.vme_end != end) &&    /* AND, we are not at the end of the requested range */
                    (entry->vme_start != tmp_entry.vme_end)) { /* AND, the next entry is not contiguous. */
                        /* found a "new" hole */
                        s = tmp_entry.vme_end;
                        rc = KERN_INVALID_ADDRESS;
                        goto done;
                }

                s = entry->vme_start;
        } /* end while loop through map entries */

done:
        if (rc == KERN_SUCCESS) {
                /* repair any damage we may have made to the VM map */
                vm_map_simplify_range(map, start, end);
        }

        vm_map_unlock(map);

        /*
         * wake up anybody waiting on entries we wired.
         */
        if (need_wakeup) {
                vm_map_entry_wakeup(map);
        }

        if (rc != KERN_SUCCESS) {
                /* undo what has been wired so far */
                vm_map_unwire_nested(map, start, s, user_wire,
                    map_pmap, pmap_addr);
                if (physpage_p) {
                        *physpage_p = 0;
                }
        }

        return rc;
}

kern_return_t
vm_map_wire_external(
        vm_map_t                map,
        vm_map_offset_t         start,
        vm_map_offset_t         end,
        vm_prot_t               caller_prot,
        boolean_t               user_wire)
{
        kern_return_t   kret;

        kret = vm_map_wire_nested(map, start, end, caller_prot, vm_tag_bt(),
            user_wire, (pmap_t)NULL, 0, NULL);
        return kret;
}

kern_return_t
vm_map_wire_kernel(
        vm_map_t                map,
        vm_map_offset_t         start,
        vm_map_offset_t         end,
        vm_prot_t               caller_prot,
        vm_tag_t                tag,
        boolean_t               user_wire)
{
        kern_return_t   kret;

        kret = vm_map_wire_nested(map, start, end, caller_prot, tag,
            user_wire, (pmap_t)NULL, 0, NULL);
        return kret;
}

kern_return_t
vm_map_wire_and_extract_external(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_prot_t       caller_prot,
        boolean_t       user_wire,
        ppnum_t         *physpage_p)
{
        kern_return_t   kret;

        kret = vm_map_wire_nested(map,
            start,
            start + VM_MAP_PAGE_SIZE(map),
            caller_prot,
            vm_tag_bt(),
            user_wire,
            (pmap_t)NULL,
            0,
            physpage_p);
        if (kret != KERN_SUCCESS &&
            physpage_p != NULL) {
                *physpage_p = 0;
        }
        return kret;
}

kern_return_t
vm_map_wire_and_extract_kernel(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_prot_t       caller_prot,
        vm_tag_t        tag,
        boolean_t       user_wire,
        ppnum_t         *physpage_p)
{
        kern_return_t   kret;

        kret = vm_map_wire_nested(map,
            start,
            start + VM_MAP_PAGE_SIZE(map),
            caller_prot,
            tag,
            user_wire,
            (pmap_t)NULL,
            0,
            physpage_p);
        if (kret != KERN_SUCCESS &&
            physpage_p != NULL) {
                *physpage_p = 0;
        }
        return kret;
}

/*
 *      vm_map_unwire:
 *
 *      Sets the pageability of the specified address range in the target
 *      as pageable.  Regions specified must have been wired previously.
 *
 *      The map must not be locked, but a reference must remain to the map
 *      throughout the call.
 *
 *      Kernel will panic on failures.  User unwire ignores holes and
 *      unwired and intransition entries to avoid losing memory by leaving
 *      it unwired.
 */
static kern_return_t
vm_map_unwire_nested(
        vm_map_t                map,
        vm_map_offset_t         start,
        vm_map_offset_t         end,
        boolean_t               user_wire,
        pmap_t                  map_pmap,
        vm_map_offset_t         pmap_addr)
{
        vm_map_entry_t          entry;
        struct vm_map_entry     *first_entry, tmp_entry;
        boolean_t               need_wakeup;
        boolean_t               main_map = FALSE;
        unsigned int            last_timestamp;

        vm_map_lock(map);
        if (map_pmap == NULL) {
                main_map = TRUE;
        }
        last_timestamp = map->timestamp;

        VM_MAP_RANGE_CHECK(map, start, end);
        assert(VM_MAP_PAGE_ALIGNED(start, VM_MAP_PAGE_MASK(map)));
        assert(VM_MAP_PAGE_ALIGNED(end, VM_MAP_PAGE_MASK(map)));

        if (start == end) {
                /* We unwired what the caller asked for: zero pages */
                vm_map_unlock(map);
                return KERN_SUCCESS;
        }

        if (vm_map_lookup_entry(map, start, &first_entry)) {
                entry = first_entry;
                /*
                 * vm_map_clip_start will be done later.
                 * We don't want to unnest any nested sub maps here !
                 */
        } else {
                if (!user_wire) {
                        panic("vm_map_unwire: start not found");
                }
                /*      Start address is not in map. */
                vm_map_unlock(map);
                return KERN_INVALID_ADDRESS;
        }

        if (entry->superpage_size) {
                /* superpages are always wired */
                vm_map_unlock(map);
                return KERN_INVALID_ADDRESS;
        }

        need_wakeup = FALSE;
        while ((entry != vm_map_to_entry(map)) && (entry->vme_start < end)) {
                if (entry->in_transition) {
                        /*
                         * 1)
                         * Another thread is wiring down this entry. Note
                         * that if it is not for the other thread we would
                         * be unwiring an unwired entry.  This is not
                         * permitted.  If we wait, we will be unwiring memory
                         * we did not wire.
                         *
                         * 2)
                         * Another thread is unwiring this entry.  We did not
                         * have a reference to it, because if we did, this
                         * entry will not be getting unwired now.
                         */
                        if (!user_wire) {
                                /*
                                 * XXX FBDP
                                 * This could happen:  there could be some
                                 * overlapping vslock/vsunlock operations
                                 * going on.
                                 * We should probably just wait and retry,
                                 * but then we have to be careful that this
                                 * entry could get "simplified" after
                                 * "in_transition" gets unset and before
                                 * we re-lookup the entry, so we would
                                 * have to re-clip the entry to avoid
                                 * re-unwiring what we have already unwired...
                                 * See vm_map_wire_nested().
                                 *
                                 * Or we could just ignore "in_transition"
                                 * here and proceed to decement the wired
                                 * count(s) on this entry.  That should be fine
                                 * as long as "wired_count" doesn't drop all
                                 * the way to 0 (and we should panic if THAT
                                 * happens).
                                 */
                                panic("vm_map_unwire: in_transition entry");
                        }

                        entry = entry->vme_next;
                        continue;
                }

                if (entry->is_sub_map) {
                        vm_map_offset_t sub_start;
                        vm_map_offset_t sub_end;
                        vm_map_offset_t local_end;
                        pmap_t          pmap;

                        vm_map_clip_start(map, entry, start);
                        vm_map_clip_end(map, entry, end);

                        sub_start = VME_OFFSET(entry);
                        sub_end = entry->vme_end - entry->vme_start;
                        sub_end += VME_OFFSET(entry);
                        local_end = entry->vme_end;
                        if (map_pmap == NULL) {
                                if (entry->use_pmap) {
                                        pmap = VME_SUBMAP(entry)->pmap;
                                        pmap_addr = sub_start;
                                } else {
                                        pmap = map->pmap;
                                        pmap_addr = start;
                                }
                                if (entry->wired_count == 0 ||
                                    (user_wire && entry->user_wired_count == 0)) {
                                        if (!user_wire) {
                                                panic("vm_map_unwire: entry is unwired");
                                        }
                                        entry = entry->vme_next;
                                        continue;
                                }

                                /*
                                 * Check for holes
                                 * Holes: Next entry should be contiguous unless
                                 * this is the end of the region.
                                 */
                                if (((entry->vme_end < end) &&
                                    ((entry->vme_next == vm_map_to_entry(map)) ||
                                    (entry->vme_next->vme_start
                                    > entry->vme_end)))) {
                                        if (!user_wire) {
                                                panic("vm_map_unwire: non-contiguous region");
                                        }
/*
 *                                       entry = entry->vme_next;
 *                                       continue;
 */
                                }

                                subtract_wire_counts(map, entry, user_wire);

                                if (entry->wired_count != 0) {
                                        entry = entry->vme_next;
                                        continue;
                                }

                                entry->in_transition = TRUE;
                                tmp_entry = *entry;/* see comment in vm_map_wire() */

                                /*
                                 * We can unlock the map now. The in_transition state
                                 * guarantees existance of the entry.
                                 */
                                vm_map_unlock(map);
                                vm_map_unwire_nested(VME_SUBMAP(entry),
                                    sub_start, sub_end, user_wire, pmap, pmap_addr);
                                vm_map_lock(map);

                                if (last_timestamp + 1 != map->timestamp) {
                                        /*
                                         * Find the entry again.  It could have been
                                         * clipped or deleted after we unlocked the map.
                                         */
                                        if (!vm_map_lookup_entry(map,
                                            tmp_entry.vme_start,
                                            &first_entry)) {
                                                if (!user_wire) {
                                                        panic("vm_map_unwire: re-lookup failed");
                                                }
                                                entry = first_entry->vme_next;
                                        } else {
                                                entry = first_entry;
                                        }
                                }
                                last_timestamp = map->timestamp;

                                /*
                                 * clear transition bit for all constituent entries
                                 * that were in the original entry (saved in
                                 * tmp_entry).  Also check for waiters.
                                 */
                                while ((entry != vm_map_to_entry(map)) &&
                                    (entry->vme_start < tmp_entry.vme_end)) {
                                        assert(entry->in_transition);
                                        entry->in_transition = FALSE;
                                        if (entry->needs_wakeup) {
                                                entry->needs_wakeup = FALSE;
                                                need_wakeup = TRUE;
                                        }
                                        entry = entry->vme_next;
                                }
                                continue;
                        } else {
                                vm_map_unlock(map);
                                vm_map_unwire_nested(VME_SUBMAP(entry),
                                    sub_start, sub_end, user_wire, map_pmap,
                                    pmap_addr);
                                vm_map_lock(map);

                                if (last_timestamp + 1 != map->timestamp) {
                                        /*
                                         * Find the entry again.  It could have been
                                         * clipped or deleted after we unlocked the map.
                                         */
                                        if (!vm_map_lookup_entry(map,
                                            tmp_entry.vme_start,
                                            &first_entry)) {
                                                if (!user_wire) {
                                                        panic("vm_map_unwire: re-lookup failed");
                                                }
                                                entry = first_entry->vme_next;
                                        } else {
                                                entry = first_entry;
                                        }
                                }
                                last_timestamp = map->timestamp;
                        }
                }


                if ((entry->wired_count == 0) ||
                    (user_wire && entry->user_wired_count == 0)) {
                        if (!user_wire) {
                                panic("vm_map_unwire: entry is unwired");
                        }

                        entry = entry->vme_next;
                        continue;
                }

                assert(entry->wired_count > 0 &&
                    (!user_wire || entry->user_wired_count > 0));

                vm_map_clip_start(map, entry, start);
                vm_map_clip_end(map, entry, end);

                /*
                 * Check for holes
                 * Holes: Next entry should be contiguous unless
                 *        this is the end of the region.
                 */
                if (((entry->vme_end < end) &&
                    ((entry->vme_next == vm_map_to_entry(map)) ||
                    (entry->vme_next->vme_start > entry->vme_end)))) {
                        if (!user_wire) {
                                panic("vm_map_unwire: non-contiguous region");
                        }
                        entry = entry->vme_next;
                        continue;
                }

                subtract_wire_counts(map, entry, user_wire);

                if (entry->wired_count != 0) {
                        entry = entry->vme_next;
                        continue;
                }

                if (entry->zero_wired_pages) {
                        entry->zero_wired_pages = FALSE;
                }

                entry->in_transition = TRUE;
                tmp_entry = *entry;     /* see comment in vm_map_wire() */

                /*
                 * We can unlock the map now. The in_transition state
                 * guarantees existance of the entry.
                 */
                vm_map_unlock(map);
                if (map_pmap) {
                        vm_fault_unwire(map,
                            &tmp_entry, FALSE, map_pmap, pmap_addr);
                } else {
                        vm_fault_unwire(map,
                            &tmp_entry, FALSE, map->pmap,
                            tmp_entry.vme_start);
                }
                vm_map_lock(map);

                if (last_timestamp + 1 != map->timestamp) {
                        /*
                         * Find the entry again.  It could have been clipped
                         * or deleted after we unlocked the map.
                         */
                        if (!vm_map_lookup_entry(map, tmp_entry.vme_start,
                            &first_entry)) {
                                if (!user_wire) {
                                        panic("vm_map_unwire: re-lookup failed");
                                }
                                entry = first_entry->vme_next;
                        } else {
                                entry = first_entry;
                        }
                }
                last_timestamp = map->timestamp;

                /*
                 * clear transition bit for all constituent entries that
                 * were in the original entry (saved in tmp_entry).  Also
                 * check for waiters.
                 */
                while ((entry != vm_map_to_entry(map)) &&
                    (entry->vme_start < tmp_entry.vme_end)) {
                        assert(entry->in_transition);
                        entry->in_transition = FALSE;
                        if (entry->needs_wakeup) {
                                entry->needs_wakeup = FALSE;
                                need_wakeup = TRUE;
                        }
                        entry = entry->vme_next;
                }
        }

        /*
         * We might have fragmented the address space when we wired this
         * range of addresses.  Attempt to re-coalesce these VM map entries
         * with their neighbors now that they're no longer wired.
         * Under some circumstances, address space fragmentation can
         * prevent VM object shadow chain collapsing, which can cause
         * swap space leaks.
         */
        vm_map_simplify_range(map, start, end);

        vm_map_unlock(map);
        /*
         * wake up anybody waiting on entries that we have unwired.
         */
        if (need_wakeup) {
                vm_map_entry_wakeup(map);
        }
        return KERN_SUCCESS;
}

kern_return_t
vm_map_unwire(
        vm_map_t                map,
        vm_map_offset_t         start,
        vm_map_offset_t         end,
        boolean_t               user_wire)
{
        return vm_map_unwire_nested(map, start, end,
                   user_wire, (pmap_t)NULL, 0);
}


/*
 *      vm_map_entry_delete:    [ internal use only ]
 *
 *      Deallocate the given entry from the target map.
 */
static void
vm_map_entry_delete(
        vm_map_t        map,
        vm_map_entry_t  entry)
{
        vm_map_offset_t s, e;
        vm_object_t     object;
        vm_map_t        submap;

        s = entry->vme_start;
        e = entry->vme_end;
        assert(VM_MAP_PAGE_ALIGNED(s, FOURK_PAGE_MASK));
        assert(VM_MAP_PAGE_ALIGNED(e, FOURK_PAGE_MASK));
        if (VM_MAP_PAGE_MASK(map) >= PAGE_MASK) {
                assert(page_aligned(s));
                assert(page_aligned(e));
        }
        if (entry->map_aligned == TRUE) {
                assert(VM_MAP_PAGE_ALIGNED(s, VM_MAP_PAGE_MASK(map)));
                assert(VM_MAP_PAGE_ALIGNED(e, VM_MAP_PAGE_MASK(map)));
        }
        assert(entry->wired_count == 0);
        assert(entry->user_wired_count == 0);
        assert(!entry->permanent);

        if (entry->is_sub_map) {
                object = NULL;
                submap = VME_SUBMAP(entry);
        } else {
                submap = NULL;
                object = VME_OBJECT(entry);
        }

        vm_map_store_entry_unlink(map, entry);
        map->size -= e - s;

        vm_map_entry_dispose(map, entry);

        vm_map_unlock(map);
        /*
         *      Deallocate the object only after removing all
         *      pmap entries pointing to its pages.
         */
        if (submap) {
                vm_map_deallocate(submap);
        } else {
                vm_object_deallocate(object);
        }
}

void
vm_map_submap_pmap_clean(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end,
        vm_map_t        sub_map,
        vm_map_offset_t offset)
{
        vm_map_offset_t submap_start;
        vm_map_offset_t submap_end;
        vm_map_size_t   remove_size;
        vm_map_entry_t  entry;

        submap_end = offset + (end - start);
        submap_start = offset;

        vm_map_lock_read(sub_map);
        if (vm_map_lookup_entry(sub_map, offset, &entry)) {
                remove_size = (entry->vme_end - entry->vme_start);
                if (offset > entry->vme_start) {
                        remove_size -= offset - entry->vme_start;
                }


                if (submap_end < entry->vme_end) {
                        remove_size -=
                            entry->vme_end - submap_end;
                }
                if (entry->is_sub_map) {
                        vm_map_submap_pmap_clean(
                                sub_map,
                                start,
                                start + remove_size,
                                VME_SUBMAP(entry),
                                VME_OFFSET(entry));
                } else {
                        if (map->mapped_in_other_pmaps &&
                            os_ref_get_count(&map->map_refcnt) != 0 &&
                            VME_OBJECT(entry) != NULL) {
                                vm_object_pmap_protect_options(
                                        VME_OBJECT(entry),
                                        (VME_OFFSET(entry) +
                                        offset -
                                        entry->vme_start),
                                        remove_size,
                                        PMAP_NULL,
                                        PAGE_SIZE,
                                        entry->vme_start,
                                        VM_PROT_NONE,
                                        PMAP_OPTIONS_REMOVE);
                        } else {
                                pmap_remove(map->pmap,
                                    (addr64_t)start,
                                    (addr64_t)(start + remove_size));
                        }
                }
        }

        entry = entry->vme_next;

        while ((entry != vm_map_to_entry(sub_map))
            && (entry->vme_start < submap_end)) {
                remove_size = (entry->vme_end - entry->vme_start);
                if (submap_end < entry->vme_end) {
                        remove_size -= entry->vme_end - submap_end;
                }
                if (entry->is_sub_map) {
                        vm_map_submap_pmap_clean(
                                sub_map,
                                (start + entry->vme_start) - offset,
                                ((start + entry->vme_start) - offset) + remove_size,
                                VME_SUBMAP(entry),
                                VME_OFFSET(entry));
                } else {
                        if (map->mapped_in_other_pmaps &&
                            os_ref_get_count(&map->map_refcnt) != 0 &&
                            VME_OBJECT(entry) != NULL) {
                                vm_object_pmap_protect_options(
                                        VME_OBJECT(entry),
                                        VME_OFFSET(entry),
                                        remove_size,
                                        PMAP_NULL,
                                        PAGE_SIZE,
                                        entry->vme_start,
                                        VM_PROT_NONE,
                                        PMAP_OPTIONS_REMOVE);
                        } else {
                                pmap_remove(map->pmap,
                                    (addr64_t)((start + entry->vme_start)
                                    - offset),
                                    (addr64_t)(((start + entry->vme_start)
                                    - offset) + remove_size));
                        }
                }
                entry = entry->vme_next;
        }
        vm_map_unlock_read(sub_map);
        return;
}

/*
 *     virt_memory_guard_ast:
 *
 *     Handle the AST callout for a virtual memory guard.
 *         raise an EXC_GUARD exception and terminate the task
 *     if configured to do so.
 */
void
virt_memory_guard_ast(
        thread_t thread,
        mach_exception_data_type_t code,
        mach_exception_data_type_t subcode)
{
        task_t task = thread->task;
        assert(task != kernel_task);
        assert(task == current_task());
        uint32_t behavior;

        behavior = task->task_exc_guard;

        /* Is delivery enabled */
        if ((behavior & TASK_EXC_GUARD_VM_DELIVER) == 0) {
                return;
        }

        /* If only once, make sure we're that once */
        while (behavior & TASK_EXC_GUARD_VM_ONCE) {
                uint32_t new_behavior = behavior & ~TASK_EXC_GUARD_VM_DELIVER;

                if (OSCompareAndSwap(behavior, new_behavior, &task->task_exc_guard)) {
                        break;
                }
                behavior = task->task_exc_guard;
                if ((behavior & TASK_EXC_GUARD_VM_DELIVER) == 0) {
                        return;
                }
        }

        /* Raise exception via corpse fork or synchronously */
        if ((task->task_exc_guard & TASK_EXC_GUARD_VM_CORPSE) &&
            (task->task_exc_guard & TASK_EXC_GUARD_VM_FATAL) == 0) {
                task_violated_guard(code, subcode, NULL);
        } else {
                task_exception_notify(EXC_GUARD, code, subcode);
        }

        /* Terminate the task if desired */
        if (task->task_exc_guard & TASK_EXC_GUARD_VM_FATAL) {
                task_bsdtask_kill(current_task());
        }
}

/*
 *     vm_map_guard_exception:
 *
 *     Generate a GUARD_TYPE_VIRTUAL_MEMORY EXC_GUARD exception.
 *
 *     Right now, we do this when we find nothing mapped, or a
 *     gap in the mapping when a user address space deallocate
 *     was requested. We report the address of the first gap found.
 */
static void
vm_map_guard_exception(
        vm_map_offset_t gap_start,
        unsigned reason)
{
        mach_exception_code_t code = 0;
        unsigned int guard_type = GUARD_TYPE_VIRT_MEMORY;
        unsigned int target = 0; /* should we pass in pid associated with map? */
        mach_exception_data_type_t subcode = (uint64_t)gap_start;
        boolean_t fatal = FALSE;

        task_t task = current_task();

        /* Can't deliver exceptions to kernel task */
        if (task == kernel_task) {
                return;
        }

        EXC_GUARD_ENCODE_TYPE(code, guard_type);
        EXC_GUARD_ENCODE_FLAVOR(code, reason);
        EXC_GUARD_ENCODE_TARGET(code, target);

        if (task->task_exc_guard & TASK_EXC_GUARD_VM_FATAL) {
                fatal = TRUE;
        }
        thread_guard_violation(current_thread(), code, subcode, fatal);
}

/*
 *      vm_map_delete:  [ internal use only ]
 *
 *      Deallocates the given address range from the target map.
 *      Removes all user wirings. Unwires one kernel wiring if
 *      VM_MAP_REMOVE_KUNWIRE is set.  Waits for kernel wirings to go
 *      away if VM_MAP_REMOVE_WAIT_FOR_KWIRE is set.  Sleeps
 *      interruptibly if VM_MAP_REMOVE_INTERRUPTIBLE is set.
 *
 *      This routine is called with map locked and leaves map locked.
 */
static kern_return_t
vm_map_delete(
        vm_map_t                map,
        vm_map_offset_t         start,
        vm_map_offset_t         end,
        int                     flags,
        vm_map_t                zap_map)
{
        vm_map_entry_t          entry, next;
        struct   vm_map_entry   *first_entry, tmp_entry;
        vm_map_offset_t         s;
        vm_object_t             object;
        boolean_t               need_wakeup;
        unsigned int            last_timestamp = ~0; /* unlikely value */
        int                     interruptible;
        vm_map_offset_t         gap_start;
        __unused vm_map_offset_t save_start = start;
        __unused vm_map_offset_t save_end = end;
        const vm_map_offset_t   FIND_GAP = 1;   /* a not page aligned value */
        const vm_map_offset_t   GAPS_OK = 2;    /* a different not page aligned value */

        if (map != kernel_map && !(flags & VM_MAP_REMOVE_GAPS_OK) && !map->terminated) {
                gap_start = FIND_GAP;
        } else {
                gap_start = GAPS_OK;
        }

        interruptible = (flags & VM_MAP_REMOVE_INTERRUPTIBLE) ?
            THREAD_ABORTSAFE : THREAD_UNINT;

        /*
         * All our DMA I/O operations in IOKit are currently done by
         * wiring through the map entries of the task requesting the I/O.
         * Because of this, we must always wait for kernel wirings
         * to go away on the entries before deleting them.
         *
         * Any caller who wants to actually remove a kernel wiring
         * should explicitly set the VM_MAP_REMOVE_KUNWIRE flag to
         * properly remove one wiring instead of blasting through
         * them all.
         */
        flags |= VM_MAP_REMOVE_WAIT_FOR_KWIRE;

        while (1) {
                /*
                 *      Find the start of the region, and clip it
                 */
                if (vm_map_lookup_entry(map, start, &first_entry)) {
                        entry = first_entry;
                        if (map == kalloc_map &&
                            (entry->vme_start != start ||
                            entry->vme_end != end)) {
                                panic("vm_map_delete(%p,0x%llx,0x%llx): "
                                    "mismatched entry %p [0x%llx:0x%llx]\n",
                                    map,
                                    (uint64_t)start,
                                    (uint64_t)end,
                                    entry,
                                    (uint64_t)entry->vme_start,
                                    (uint64_t)entry->vme_end);
                        }

                        /*
                         * If in a superpage, extend the range to include the start of the mapping.
                         */
                        if (entry->superpage_size && (start & ~SUPERPAGE_MASK)) {
                                start = SUPERPAGE_ROUND_DOWN(start);
                                continue;
                        }

                        if (start == entry->vme_start) {
                                /*
                                 * No need to clip.  We don't want to cause
                                 * any unnecessary unnesting in this case...
                                 */
                        } else {
                                if ((flags & VM_MAP_REMOVE_NO_MAP_ALIGN) &&
                                    entry->map_aligned &&
                                    !VM_MAP_PAGE_ALIGNED(
                                            start,
                                            VM_MAP_PAGE_MASK(map))) {
                                        /*
                                         * The entry will no longer be
                                         * map-aligned after clipping
                                         * and the caller said it's OK.
                                         */
                                        entry->map_aligned = FALSE;
                                }
                                if (map == kalloc_map) {
                                        panic("vm_map_delete(%p,0x%llx,0x%llx):"
                                            " clipping %p at 0x%llx\n",
                                            map,
                                            (uint64_t)start,
                                            (uint64_t)end,
                                            entry,
                                            (uint64_t)start);
                                }
                                vm_map_clip_start(map, entry, start);
                        }

                        /*
                         *      Fix the lookup hint now, rather than each
                         *      time through the loop.
                         */
                        SAVE_HINT_MAP_WRITE(map, entry->vme_prev);
                } else {
                        if (map->pmap == kernel_pmap &&
                            os_ref_get_count(&map->map_refcnt) != 0) {
                                panic("vm_map_delete(%p,0x%llx,0x%llx): "
                                    "no map entry at 0x%llx\n",
                                    map,
                                    (uint64_t)start,
                                    (uint64_t)end,
                                    (uint64_t)start);
                        }
                        entry = first_entry->vme_next;
                        if (gap_start == FIND_GAP) {
                                gap_start = start;
                        }
                }
                break;
        }
        if (entry->superpage_size) {
                end = SUPERPAGE_ROUND_UP(end);
        }

        need_wakeup = FALSE;
        /*
         *      Step through all entries in this region
         */
        s = entry->vme_start;
        while ((entry != vm_map_to_entry(map)) && (s < end)) {
                /*
                 * At this point, we have deleted all the memory entries
                 * between "start" and "s".  We still need to delete
                 * all memory entries between "s" and "end".
                 * While we were blocked and the map was unlocked, some
                 * new memory entries could have been re-allocated between
                 * "start" and "s" and we don't want to mess with those.
                 * Some of those entries could even have been re-assembled
                 * with an entry after "s" (in vm_map_simplify_entry()), so
                 * we may have to vm_map_clip_start() again.
                 */

                if (entry->vme_start >= s) {
                        /*
                         * This entry starts on or after "s"
                         * so no need to clip its start.
                         */
                } else {
                        /*
                         * This entry has been re-assembled by a
                         * vm_map_simplify_entry().  We need to
                         * re-clip its start.
                         */
                        if ((flags & VM_MAP_REMOVE_NO_MAP_ALIGN) &&
                            entry->map_aligned &&
                            !VM_MAP_PAGE_ALIGNED(s,
                            VM_MAP_PAGE_MASK(map))) {
                                /*
                                 * The entry will no longer be map-aligned
                                 * after clipping and the caller said it's OK.
                                 */
                                entry->map_aligned = FALSE;
                        }
                        if (map == kalloc_map) {
                                panic("vm_map_delete(%p,0x%llx,0x%llx): "
                                    "clipping %p at 0x%llx\n",
                                    map,
                                    (uint64_t)start,
                                    (uint64_t)end,
                                    entry,
                                    (uint64_t)s);
                        }
                        vm_map_clip_start(map, entry, s);
                }
                if (entry->vme_end <= end) {
                        /*
                         * This entry is going away completely, so no need
                         * to clip and possibly cause an unnecessary unnesting.
                         */
                } else {
                        if ((flags & VM_MAP_REMOVE_NO_MAP_ALIGN) &&
                            entry->map_aligned &&
                            !VM_MAP_PAGE_ALIGNED(end,
                            VM_MAP_PAGE_MASK(map))) {
                                /*
                                 * The entry will no longer be map-aligned
                                 * after clipping and the caller said it's OK.
                                 */
                                entry->map_aligned = FALSE;
                        }
                        if (map == kalloc_map) {
                                panic("vm_map_delete(%p,0x%llx,0x%llx): "
                                    "clipping %p at 0x%llx\n",
                                    map,
                                    (uint64_t)start,
                                    (uint64_t)end,
                                    entry,
                                    (uint64_t)end);
                        }
                        vm_map_clip_end(map, entry, end);
                }

                if (entry->permanent) {
                        if (map->pmap == kernel_pmap) {
                                panic("%s(%p,0x%llx,0x%llx): "
                                    "attempt to remove permanent "
                                    "VM map entry "
                                    "%p [0x%llx:0x%llx]\n",
                                    __FUNCTION__,
                                    map,
                                    (uint64_t) start,
                                    (uint64_t) end,
                                    entry,
                                    (uint64_t) entry->vme_start,
                                    (uint64_t) entry->vme_end);
                        } else if (flags & VM_MAP_REMOVE_IMMUTABLE) {
//                              printf("FBDP %d[%s] removing permanent entry %p [0x%llx:0x%llx] prot 0x%x/0x%x\n", proc_selfpid(), (current_task()->bsd_info ? proc_name_address(current_task()->bsd_info) : "?"), entry, (uint64_t)entry->vme_start, (uint64_t)entry->vme_end, entry->protection, entry->max_protection);
                                entry->permanent = FALSE;
                        } else {
                                if (vm_map_executable_immutable_verbose) {
                                        printf("%d[%s] %s(0x%llx,0x%llx): "
                                            "permanent entry [0x%llx:0x%llx] "
                                            "prot 0x%x/0x%x\n",
                                            proc_selfpid(),
                                            (current_task()->bsd_info
                                            ? proc_name_address(current_task()->bsd_info)
                                            : "?"),
                                            __FUNCTION__,
                                            (uint64_t) start,
                                            (uint64_t) end,
                                            (uint64_t)entry->vme_start,
                                            (uint64_t)entry->vme_end,
                                            entry->protection,
                                            entry->max_protection);
                                }
                                /*
                                 * dtrace -n 'vm_map_delete_permanent { print("start=0x%llx end=0x%llx prot=0x%x/0x%x\n", arg0, arg1, arg2, arg3); stack(); ustack(); }'
                                 */
                                DTRACE_VM5(vm_map_delete_permanent,
                                    vm_map_offset_t, entry->vme_start,
                                    vm_map_offset_t, entry->vme_end,
                                    vm_prot_t, entry->protection,
                                    vm_prot_t, entry->max_protection,
                                    int, VME_ALIAS(entry));
                        }
                }


                if (entry->in_transition) {
                        wait_result_t wait_result;

                        /*
                         * Another thread is wiring/unwiring this entry.
                         * Let the other thread know we are waiting.
                         */
                        assert(s == entry->vme_start);
                        entry->needs_wakeup = TRUE;

                        /*
                         * wake up anybody waiting on entries that we have
                         * already unwired/deleted.
                         */
                        if (need_wakeup) {
                                vm_map_entry_wakeup(map);
                                need_wakeup = FALSE;
                        }

                        wait_result = vm_map_entry_wait(map, interruptible);

                        if (interruptible &&
                            wait_result == THREAD_INTERRUPTED) {
                                /*
                                 * We do not clear the needs_wakeup flag,
                                 * since we cannot tell if we were the only one.
                                 */
                                return KERN_ABORTED;
                        }

                        /*
                         * The entry could have been clipped or it
                         * may not exist anymore.  Look it up again.
                         */
                        if (!vm_map_lookup_entry(map, s, &first_entry)) {
                                /*
                                 * User: use the next entry
                                 */
                                if (gap_start == FIND_GAP) {
                                        gap_start = s;
                                }
                                entry = first_entry->vme_next;
                                s = entry->vme_start;
                        } else {
                                entry = first_entry;
                                SAVE_HINT_MAP_WRITE(map, entry->vme_prev);
                        }
                        last_timestamp = map->timestamp;
                        continue;
                } /* end in_transition */

                if (entry->wired_count) {
                        boolean_t       user_wire;

                        user_wire = entry->user_wired_count > 0;

                        /*
                         *      Remove a kernel wiring if requested
                         */
                        if (flags & VM_MAP_REMOVE_KUNWIRE) {
                                entry->wired_count--;
                        }

                        /*
                         *      Remove all user wirings for proper accounting
                         */
                        if (entry->user_wired_count > 0) {
                                while (entry->user_wired_count) {
                                        subtract_wire_counts(map, entry, user_wire);
                                }
                        }

                        if (entry->wired_count != 0) {
                                assert(map != kernel_map);
                                /*
                                 * Cannot continue.  Typical case is when
                                 * a user thread has physical io pending on
                                 * on this page.  Either wait for the
                                 * kernel wiring to go away or return an
                                 * error.
                                 */
                                if (flags & VM_MAP_REMOVE_WAIT_FOR_KWIRE) {
                                        wait_result_t wait_result;

                                        assert(s == entry->vme_start);
                                        entry->needs_wakeup = TRUE;
                                        wait_result = vm_map_entry_wait(map,
                                            interruptible);

                                        if (interruptible &&
                                            wait_result == THREAD_INTERRUPTED) {
                                                /*
                                                 * We do not clear the
                                                 * needs_wakeup flag, since we
                                                 * cannot tell if we were the
                                                 * only one.
                                                 */
                                                return KERN_ABORTED;
                                        }

                                        /*
                                         * The entry could have been clipped or
                                         * it may not exist anymore.  Look it
                                         * up again.
                                         */
                                        if (!vm_map_lookup_entry(map, s,
                                            &first_entry)) {
                                                assert(map != kernel_map);
                                                /*
                                                 * User: use the next entry
                                                 */
                                                if (gap_start == FIND_GAP) {
                                                        gap_start = s;
                                                }
                                                entry = first_entry->vme_next;
                                                s = entry->vme_start;
                                        } else {
                                                entry = first_entry;
                                                SAVE_HINT_MAP_WRITE(map, entry->vme_prev);
                                        }
                                        last_timestamp = map->timestamp;
                                        continue;
                                } else {
                                        return KERN_FAILURE;
                                }
                        }

                        entry->in_transition = TRUE;
                        /*
                         * copy current entry.  see comment in vm_map_wire()
                         */
                        tmp_entry = *entry;
                        assert(s == entry->vme_start);

                        /*
                         * We can unlock the map now. The in_transition
                         * state guarentees existance of the entry.
                         */
                        vm_map_unlock(map);

                        if (tmp_entry.is_sub_map) {
                                vm_map_t sub_map;
                                vm_map_offset_t sub_start, sub_end;
                                pmap_t pmap;
                                vm_map_offset_t pmap_addr;


                                sub_map = VME_SUBMAP(&tmp_entry);
                                sub_start = VME_OFFSET(&tmp_entry);
                                sub_end = sub_start + (tmp_entry.vme_end -
                                    tmp_entry.vme_start);
                                if (tmp_entry.use_pmap) {
                                        pmap = sub_map->pmap;
                                        pmap_addr = tmp_entry.vme_start;
                                } else {
                                        pmap = map->pmap;
                                        pmap_addr = tmp_entry.vme_start;
                                }
                                (void) vm_map_unwire_nested(sub_map,
                                    sub_start, sub_end,
                                    user_wire,
                                    pmap, pmap_addr);
                        } else {
                                if (VME_OBJECT(&tmp_entry) == kernel_object) {
                                        pmap_protect_options(
                                                map->pmap,
                                                tmp_entry.vme_start,
                                                tmp_entry.vme_end,
                                                VM_PROT_NONE,
                                                PMAP_OPTIONS_REMOVE,
                                                NULL);
                                }
                                vm_fault_unwire(map, &tmp_entry,
                                    VME_OBJECT(&tmp_entry) == kernel_object,
                                    map->pmap, tmp_entry.vme_start);
                        }

                        vm_map_lock(map);

                        if (last_timestamp + 1 != map->timestamp) {
                                /*
                                 * Find the entry again.  It could have
                                 * been clipped after we unlocked the map.
                                 */
                                if (!vm_map_lookup_entry(map, s, &first_entry)) {
                                        assert((map != kernel_map) &&
                                            (!entry->is_sub_map));
                                        if (gap_start == FIND_GAP) {
                                                gap_start = s;
                                        }
                                        first_entry = first_entry->vme_next;
                                        s = first_entry->vme_start;
                                } else {
                                        SAVE_HINT_MAP_WRITE(map, entry->vme_prev);
                                }
                        } else {
                                SAVE_HINT_MAP_WRITE(map, entry->vme_prev);
                                first_entry = entry;
                        }

                        last_timestamp = map->timestamp;

                        entry = first_entry;
                        while ((entry != vm_map_to_entry(map)) &&
                            (entry->vme_start < tmp_entry.vme_end)) {
                                assert(entry->in_transition);
                                entry->in_transition = FALSE;
                                if (entry->needs_wakeup) {
                                        entry->needs_wakeup = FALSE;
                                        need_wakeup = TRUE;
                                }
                                entry = entry->vme_next;
                        }
                        /*
                         * We have unwired the entry(s).  Go back and
                         * delete them.
                         */
                        entry = first_entry;
                        continue;
                }

                /* entry is unwired */
                assert(entry->wired_count == 0);
                assert(entry->user_wired_count == 0);

                assert(s == entry->vme_start);

                if (flags & VM_MAP_REMOVE_NO_PMAP_CLEANUP) {
                        /*
                         * XXX with the VM_MAP_REMOVE_SAVE_ENTRIES flag to
                         * vm_map_delete(), some map entries might have been
                         * transferred to a "zap_map", which doesn't have a
                         * pmap.  The original pmap has already been flushed
                         * in the vm_map_delete() call targeting the original
                         * map, but when we get to destroying the "zap_map",
                         * we don't have any pmap to flush, so let's just skip
                         * all this.
                         */
                } else if (entry->is_sub_map) {
                        assertf(VM_MAP_PAGE_SHIFT(VME_SUBMAP(entry)) >= VM_MAP_PAGE_SHIFT(map),
                            "map %p (%d) entry %p submap %p (%d)\n",
                            map, VM_MAP_PAGE_SHIFT(map), entry,
                            VME_SUBMAP(entry),
                            VM_MAP_PAGE_SHIFT(VME_SUBMAP(entry)));
                        if (entry->use_pmap) {
                                assertf(VM_MAP_PAGE_SHIFT(VME_SUBMAP(entry)) == VM_MAP_PAGE_SHIFT(map),
                                    "map %p (%d) entry %p submap %p (%d)\n",
                                    map, VM_MAP_PAGE_SHIFT(map), entry,
                                    VME_SUBMAP(entry),
                                    VM_MAP_PAGE_SHIFT(VME_SUBMAP(entry)));
#ifndef NO_NESTED_PMAP
                                int pmap_flags;

                                if (flags & VM_MAP_REMOVE_NO_UNNESTING) {
                                        /*
                                         * This is the final cleanup of the
                                         * address space being terminated.
                                         * No new mappings are expected and
                                         * we don't really need to unnest the
                                         * shared region (and lose the "global"
                                         * pmap mappings, if applicable).
                                         *
                                         * Tell the pmap layer that we're
                                         * "clean" wrt nesting.
                                         */
                                        pmap_flags = PMAP_UNNEST_CLEAN;
                                } else {
                                        /*
                                         * We're unmapping part of the nested
                                         * shared region, so we can't keep the
                                         * nested pmap.
                                         */
                                        pmap_flags = 0;
                                }
                                pmap_unnest_options(
                                        map->pmap,
                                        (addr64_t)entry->vme_start,
                                        entry->vme_end - entry->vme_start,
                                        pmap_flags);
#endif  /* NO_NESTED_PMAP */
                                if (map->mapped_in_other_pmaps &&
                                    os_ref_get_count(&map->map_refcnt) != 0) {
                                        /* clean up parent map/maps */
                                        vm_map_submap_pmap_clean(
                                                map, entry->vme_start,
                                                entry->vme_end,
                                                VME_SUBMAP(entry),
                                                VME_OFFSET(entry));
                                }
                        } else {
                                vm_map_submap_pmap_clean(
                                        map, entry->vme_start, entry->vme_end,
                                        VME_SUBMAP(entry),
                                        VME_OFFSET(entry));
                        }
                } else if (VME_OBJECT(entry) != kernel_object &&
                    VME_OBJECT(entry) != compressor_object) {
                        object = VME_OBJECT(entry);
                        if (map->mapped_in_other_pmaps &&
                            os_ref_get_count(&map->map_refcnt) != 0) {
                                vm_object_pmap_protect_options(
                                        object, VME_OFFSET(entry),
                                        entry->vme_end - entry->vme_start,
                                        PMAP_NULL,
                                        PAGE_SIZE,
                                        entry->vme_start,
                                        VM_PROT_NONE,
                                        PMAP_OPTIONS_REMOVE);
                        } else if ((VME_OBJECT(entry) != VM_OBJECT_NULL) ||
                            (map->pmap == kernel_pmap)) {
                                /* Remove translations associated
                                 * with this range unless the entry
                                 * does not have an object, or
                                 * it's the kernel map or a descendant
                                 * since the platform could potentially
                                 * create "backdoor" mappings invisible
                                 * to the VM. It is expected that
                                 * objectless, non-kernel ranges
                                 * do not have such VM invisible
                                 * translations.
                                 */
                                pmap_remove_options(map->pmap,
                                    (addr64_t)entry->vme_start,
                                    (addr64_t)entry->vme_end,
                                    PMAP_OPTIONS_REMOVE);
                        }
                }

                if (entry->iokit_acct) {
                        /* alternate accounting */
                        DTRACE_VM4(vm_map_iokit_unmapped_region,
                            vm_map_t, map,
                            vm_map_offset_t, entry->vme_start,
                            vm_map_offset_t, entry->vme_end,
                            int, VME_ALIAS(entry));
                        vm_map_iokit_unmapped_region(map,
                            (entry->vme_end -
                            entry->vme_start));
                        entry->iokit_acct = FALSE;
                        entry->use_pmap = FALSE;
                }

                /*
                 * All pmap mappings for this map entry must have been
                 * cleared by now.
                 */
#if DEBUG
                assert(vm_map_pmap_is_empty(map,
                    entry->vme_start,
                    entry->vme_end));
#endif /* DEBUG */

                next = entry->vme_next;

                if (map->pmap == kernel_pmap &&
                    os_ref_get_count(&map->map_refcnt) != 0 &&
                    entry->vme_end < end &&
                    (next == vm_map_to_entry(map) ||
                    next->vme_start != entry->vme_end)) {
                        panic("vm_map_delete(%p,0x%llx,0x%llx): "
                            "hole after %p at 0x%llx\n",
                            map,
                            (uint64_t)start,
                            (uint64_t)end,
                            entry,
                            (uint64_t)entry->vme_end);
                }

                /*
                 * If the desired range didn't end with "entry", then there is a gap if
                 * we wrapped around to the start of the map or if "entry" and "next"
                 * aren't contiguous.
                 *
                 * The vm_map_round_page() is needed since an entry can be less than VM_MAP_PAGE_MASK() sized.
                 * For example, devices which have h/w 4K pages, but entry sizes are all now 16K.
                 */
                if (gap_start == FIND_GAP &&
                    vm_map_round_page(entry->vme_end, VM_MAP_PAGE_MASK(map)) < end &&
                    (next == vm_map_to_entry(map) || entry->vme_end != next->vme_start)) {
                        gap_start = entry->vme_end;
                }
                s = next->vme_start;
                last_timestamp = map->timestamp;

                if (entry->permanent) {
                        /*
                         * A permanent entry can not be removed, so leave it
                         * in place but remove all access permissions.
                         */
                        entry->protection = VM_PROT_NONE;
                        entry->max_protection = VM_PROT_NONE;
                } else if ((flags & VM_MAP_REMOVE_SAVE_ENTRIES) &&
                    zap_map != VM_MAP_NULL) {
                        vm_map_size_t entry_size;
                        /*
                         * The caller wants to save the affected VM map entries
                         * into the "zap_map".  The caller will take care of
                         * these entries.
                         */
                        /* unlink the entry from "map" ... */
                        vm_map_store_entry_unlink(map, entry);
                        /* ... and add it to the end of the "zap_map" */
                        vm_map_store_entry_link(zap_map,
                            vm_map_last_entry(zap_map),
                            entry,
                            VM_MAP_KERNEL_FLAGS_NONE);
                        entry_size = entry->vme_end - entry->vme_start;
                        map->size -= entry_size;
                        zap_map->size += entry_size;
                        /* we didn't unlock the map, so no timestamp increase */
                        last_timestamp--;
                } else {
                        vm_map_entry_delete(map, entry);
                        /* vm_map_entry_delete unlocks the map */
                        vm_map_lock(map);
                }

                entry = next;

                if (entry == vm_map_to_entry(map)) {
                        break;
                }
                if (last_timestamp + 1 != map->timestamp) {
                        /*
                         * We are responsible for deleting everything
                         * from the given space. If someone has interfered,
                         * we pick up where we left off. Back fills should
                         * be all right for anyone, except map_delete, and
                         * we have to assume that the task has been fully
                         * disabled before we get here
                         */
                        if (!vm_map_lookup_entry(map, s, &entry)) {
                                entry = entry->vme_next;

                                /*
                                 * Nothing found for s. If we weren't already done, then there is a gap.
                                 */
                                if (gap_start == FIND_GAP && s < end) {
                                        gap_start = s;
                                }
                                s = entry->vme_start;
                        } else {
                                SAVE_HINT_MAP_WRITE(map, entry->vme_prev);
                        }
                        /*
                         * others can not only allocate behind us, we can
                         * also see coalesce while we don't have the map lock
                         */
                        if (entry == vm_map_to_entry(map)) {
                                break;
                        }
                }
                last_timestamp = map->timestamp;
        }

        if (map->wait_for_space) {
                thread_wakeup((event_t) map);
        }
        /*
         * wake up anybody waiting on entries that we have already deleted.
         */
        if (need_wakeup) {
                vm_map_entry_wakeup(map);
        }

        if (gap_start != FIND_GAP && gap_start != GAPS_OK) {
                DTRACE_VM3(kern_vm_deallocate_gap,
                    vm_map_offset_t, gap_start,
                    vm_map_offset_t, save_start,
                    vm_map_offset_t, save_end);
                if (!(flags & VM_MAP_REMOVE_GAPS_OK)) {
                        vm_map_guard_exception(gap_start, kGUARD_EXC_DEALLOC_GAP);
                }
        }

        return KERN_SUCCESS;
}


/*
 *      vm_map_terminate:
 *
 *      Clean out a task's map.
 */
kern_return_t
vm_map_terminate(
        vm_map_t        map)
{
        vm_map_lock(map);
        map->terminated = TRUE;
        vm_map_unlock(map);

        return vm_map_remove(map,
                   map->min_offset,
                   map->max_offset,
                   /*
                    * Final cleanup:
                    * + no unnesting
                    * + remove immutable mappings
                    * + allow gaps in range
                    */
                   (VM_MAP_REMOVE_NO_UNNESTING |
                   VM_MAP_REMOVE_IMMUTABLE |
                   VM_MAP_REMOVE_GAPS_OK));
}

/*
 *      vm_map_remove:
 *
 *      Remove the given address range from the target map.
 *      This is the exported form of vm_map_delete.
 */
kern_return_t
vm_map_remove(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end,
        boolean_t      flags)
{
        kern_return_t   result;

        vm_map_lock(map);
        VM_MAP_RANGE_CHECK(map, start, end);
        /*
         * For the zone maps, the kernel controls the allocation/freeing of memory.
         * Any free to the zone maps should be within the bounds of the map and
         * should free up memory. If the VM_MAP_RANGE_CHECK() silently converts a
         * free to the zone maps into a no-op, there is a problem and we should
         * panic.
         */
        if ((start == end) && zone_maps_owned(start, 1)) {
                panic("Nothing being freed to a zone map. start = end = %p\n", (void *)start);
        }
        result = vm_map_delete(map, start, end, flags, VM_MAP_NULL);
        vm_map_unlock(map);

        return result;
}

/*
 *      vm_map_remove_locked:
 *
 *      Remove the given address range from the target locked map.
 *      This is the exported form of vm_map_delete.
 */
kern_return_t
vm_map_remove_locked(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end,
        boolean_t       flags)
{
        kern_return_t   result;

        VM_MAP_RANGE_CHECK(map, start, end);
        result = vm_map_delete(map, start, end, flags, VM_MAP_NULL);
        return result;
}


/*
 *      Routine:        vm_map_copy_allocate
 *
 *      Description:
 *              Allocates and initializes a map copy object.
 */
static vm_map_copy_t
vm_map_copy_allocate(void)
{
        vm_map_copy_t new_copy;

        new_copy = zalloc(vm_map_copy_zone);
        bzero(new_copy, sizeof(*new_copy));
        new_copy->c_u.hdr.rb_head_store.rbh_root = (void*)(int)SKIP_RB_TREE;
        vm_map_copy_first_entry(new_copy) = vm_map_copy_to_entry(new_copy);
        vm_map_copy_last_entry(new_copy) = vm_map_copy_to_entry(new_copy);
        return new_copy;
}

/*
 *      Routine:        vm_map_copy_discard
 *
 *      Description:
 *              Dispose of a map copy object (returned by
 *              vm_map_copyin).
 */
void
vm_map_copy_discard(
        vm_map_copy_t   copy)
{
        if (copy == VM_MAP_COPY_NULL) {
                return;
        }

        switch (copy->type) {
        case VM_MAP_COPY_ENTRY_LIST:
                while (vm_map_copy_first_entry(copy) !=
                    vm_map_copy_to_entry(copy)) {
                        vm_map_entry_t  entry = vm_map_copy_first_entry(copy);

                        vm_map_copy_entry_unlink(copy, entry);
                        if (entry->is_sub_map) {
                                vm_map_deallocate(VME_SUBMAP(entry));
                        } else {
                                vm_object_deallocate(VME_OBJECT(entry));
                        }
                        vm_map_copy_entry_dispose(copy, entry);
                }
                break;
        case VM_MAP_COPY_OBJECT:
                vm_object_deallocate(copy->cpy_object);
                break;
        case VM_MAP_COPY_KERNEL_BUFFER:

                /*
                 * The vm_map_copy_t and possibly the data buffer were
                 * allocated by a single call to kheap_alloc(), i.e. the
                 * vm_map_copy_t was not allocated out of the zone.
                 */
                if (copy->size > msg_ool_size_small || copy->offset) {
                        panic("Invalid vm_map_copy_t sz:%lld, ofst:%lld",
                            (long long)copy->size, (long long)copy->offset);
                }
                kheap_free(KHEAP_DATA_BUFFERS, copy->cpy_kdata, copy->size);
        }
        zfree(vm_map_copy_zone, copy);
}

/*
 *      Routine:        vm_map_copy_copy
 *
 *      Description:
 *                      Move the information in a map copy object to
 *                      a new map copy object, leaving the old one
 *                      empty.
 *
 *                      This is used by kernel routines that need
 *                      to look at out-of-line data (in copyin form)
 *                      before deciding whether to return SUCCESS.
 *                      If the routine returns FAILURE, the original
 *                      copy object will be deallocated; therefore,
 *                      these routines must make a copy of the copy
 *                      object and leave the original empty so that
 *                      deallocation will not fail.
 */
vm_map_copy_t
vm_map_copy_copy(
        vm_map_copy_t   copy)
{
        vm_map_copy_t   new_copy;

        if (copy == VM_MAP_COPY_NULL) {
                return VM_MAP_COPY_NULL;
        }

        /*
         * Allocate a new copy object, and copy the information
         * from the old one into it.
         */

        new_copy = (vm_map_copy_t) zalloc(vm_map_copy_zone);
        memcpy((void *) new_copy, (void *) copy, sizeof(struct vm_map_copy));
#if __has_feature(ptrauth_calls)
        if (copy->type == VM_MAP_COPY_KERNEL_BUFFER) {
                new_copy->cpy_kdata = copy->cpy_kdata;
        }
#endif

        if (copy->type == VM_MAP_COPY_ENTRY_LIST) {
                /*
                 * The links in the entry chain must be
                 * changed to point to the new copy object.
                 */
                vm_map_copy_first_entry(copy)->vme_prev
                        = vm_map_copy_to_entry(new_copy);
                vm_map_copy_last_entry(copy)->vme_next
                        = vm_map_copy_to_entry(new_copy);
        }

        /*
         * Change the old copy object into one that contains
         * nothing to be deallocated.
         */
        copy->type = VM_MAP_COPY_OBJECT;
        copy->cpy_object = VM_OBJECT_NULL;

        /*
         * Return the new object.
         */
        return new_copy;
}

static kern_return_t
vm_map_overwrite_submap_recurse(
        vm_map_t        dst_map,
        vm_map_offset_t dst_addr,
        vm_map_size_t   dst_size)
{
        vm_map_offset_t dst_end;
        vm_map_entry_t  tmp_entry;
        vm_map_entry_t  entry;
        kern_return_t   result;
        boolean_t       encountered_sub_map = FALSE;



        /*
         *      Verify that the destination is all writeable
         *      initially.  We have to trunc the destination
         *      address and round the copy size or we'll end up
         *      splitting entries in strange ways.
         */

        dst_end = vm_map_round_page(dst_addr + dst_size,
            VM_MAP_PAGE_MASK(dst_map));
        vm_map_lock(dst_map);

start_pass_1:
        if (!vm_map_lookup_entry(dst_map, dst_addr, &tmp_entry)) {
                vm_map_unlock(dst_map);
                return KERN_INVALID_ADDRESS;
        }

        vm_map_clip_start(dst_map,
            tmp_entry,
            vm_map_trunc_page(dst_addr,
            VM_MAP_PAGE_MASK(dst_map)));
        if (tmp_entry->is_sub_map) {
                /* clipping did unnest if needed */
                assert(!tmp_entry->use_pmap);
        }

        for (entry = tmp_entry;;) {
                vm_map_entry_t  next;

                next = entry->vme_next;
                while (entry->is_sub_map) {
                        vm_map_offset_t sub_start;
                        vm_map_offset_t sub_end;
                        vm_map_offset_t local_end;

                        if (entry->in_transition) {
                                /*
                                 * Say that we are waiting, and wait for entry.
                                 */
                                entry->needs_wakeup = TRUE;
                                vm_map_entry_wait(dst_map, THREAD_UNINT);

                                goto start_pass_1;
                        }

                        encountered_sub_map = TRUE;
                        sub_start = VME_OFFSET(entry);

                        if (entry->vme_end < dst_end) {
                                sub_end = entry->vme_end;
                        } else {
                                sub_end = dst_end;
                        }
                        sub_end -= entry->vme_start;
                        sub_end += VME_OFFSET(entry);
                        local_end = entry->vme_end;
                        vm_map_unlock(dst_map);

                        result = vm_map_overwrite_submap_recurse(
                                VME_SUBMAP(entry),
                                sub_start,
                                sub_end - sub_start);

                        if (result != KERN_SUCCESS) {
                                return result;
                        }
                        if (dst_end <= entry->vme_end) {
                                return KERN_SUCCESS;
                        }
                        vm_map_lock(dst_map);
                        if (!vm_map_lookup_entry(dst_map, local_end,
                            &tmp_entry)) {
                                vm_map_unlock(dst_map);
                                return KERN_INVALID_ADDRESS;
                        }
                        entry = tmp_entry;
                        next = entry->vme_next;
                }

                if (!(entry->protection & VM_PROT_WRITE)) {
                        vm_map_unlock(dst_map);
                        return KERN_PROTECTION_FAILURE;
                }

                /*
                 *      If the entry is in transition, we must wait
                 *      for it to exit that state.  Anything could happen
                 *      when we unlock the map, so start over.
                 */
                if (entry->in_transition) {
                        /*
                         * Say that we are waiting, and wait for entry.
                         */
                        entry->needs_wakeup = TRUE;
                        vm_map_entry_wait(dst_map, THREAD_UNINT);

                        goto start_pass_1;
                }

/*
 *              our range is contained completely within this map entry
 */
                if (dst_end <= entry->vme_end) {
                        vm_map_unlock(dst_map);
                        return KERN_SUCCESS;
                }
/*
 *              check that range specified is contiguous region
 */
                if ((next == vm_map_to_entry(dst_map)) ||
                    (next->vme_start != entry->vme_end)) {
                        vm_map_unlock(dst_map);
                        return KERN_INVALID_ADDRESS;
                }

                /*
                 *      Check for permanent objects in the destination.
                 */
                if ((VME_OBJECT(entry) != VM_OBJECT_NULL) &&
                    ((!VME_OBJECT(entry)->internal) ||
                    (VME_OBJECT(entry)->true_share))) {
                        if (encountered_sub_map) {
                                vm_map_unlock(dst_map);
                                return KERN_FAILURE;
                        }
                }


                entry = next;
        }/* for */
        vm_map_unlock(dst_map);
        return KERN_SUCCESS;
}

/*
 *      Routine:        vm_map_copy_overwrite
 *
 *      Description:
 *              Copy the memory described by the map copy
 *              object (copy; returned by vm_map_copyin) onto
 *              the specified destination region (dst_map, dst_addr).
 *              The destination must be writeable.
 *
 *              Unlike vm_map_copyout, this routine actually
 *              writes over previously-mapped memory.  If the
 *              previous mapping was to a permanent (user-supplied)
 *              memory object, it is preserved.
 *
 *              The attributes (protection and inheritance) of the
 *              destination region are preserved.
 *
 *              If successful, consumes the copy object.
 *              Otherwise, the caller is responsible for it.
 *
 *      Implementation notes:
 *              To overwrite aligned temporary virtual memory, it is
 *              sufficient to remove the previous mapping and insert
 *              the new copy.  This replacement is done either on
 *              the whole region (if no permanent virtual memory
 *              objects are embedded in the destination region) or
 *              in individual map entries.
 *
 *              To overwrite permanent virtual memory , it is necessary
 *              to copy each page, as the external memory management
 *              interface currently does not provide any optimizations.
 *
 *              Unaligned memory also has to be copied.  It is possible
 *              to use 'vm_trickery' to copy the aligned data.  This is
 *              not done but not hard to implement.
 *
 *              Once a page of permanent memory has been overwritten,
 *              it is impossible to interrupt this function; otherwise,
 *              the call would be neither atomic nor location-independent.
 *              The kernel-state portion of a user thread must be
 *              interruptible.
 *
 *              It may be expensive to forward all requests that might
 *              overwrite permanent memory (vm_write, vm_copy) to
 *              uninterruptible kernel threads.  This routine may be
 *              called by interruptible threads; however, success is
 *              not guaranteed -- if the request cannot be performed
 *              atomically and interruptibly, an error indication is
 *              returned.
 */

static kern_return_t
vm_map_copy_overwrite_nested(
        vm_map_t                dst_map,
        vm_map_address_t        dst_addr,
        vm_map_copy_t           copy,
        boolean_t               interruptible,
        pmap_t                  pmap,
        boolean_t               discard_on_success)
{
        vm_map_offset_t         dst_end;
        vm_map_entry_t          tmp_entry;
        vm_map_entry_t          entry;
        kern_return_t           kr;
        boolean_t               aligned = TRUE;
        boolean_t               contains_permanent_objects = FALSE;
        boolean_t               encountered_sub_map = FALSE;
        vm_map_offset_t         base_addr;
        vm_map_size_t           copy_size;
        vm_map_size_t           total_size;
        int                     copy_page_shift;


        /*
         *      Check for null copy object.
         */

        if (copy == VM_MAP_COPY_NULL) {
                return KERN_SUCCESS;
        }

        /*
         * Assert that the vm_map_copy is coming from the right
         * zone and hasn't been forged
         */
        vm_map_copy_require(copy);

        /*
         *      Check for special kernel buffer allocated
         *      by new_ipc_kmsg_copyin.
         */

        if (copy->type == VM_MAP_COPY_KERNEL_BUFFER) {
                return vm_map_copyout_kernel_buffer(
                        dst_map, &dst_addr,
                        copy, copy->size, TRUE, discard_on_success);
        }

        /*
         *      Only works for entry lists at the moment.  Will
         *      support page lists later.
         */

        assert(copy->type == VM_MAP_COPY_ENTRY_LIST);

        if (copy->size == 0) {
                if (discard_on_success) {
                        vm_map_copy_discard(copy);
                }
                return KERN_SUCCESS;
        }

        copy_page_shift = copy->cpy_hdr.page_shift;

        /*
         *      Verify that the destination is all writeable
         *      initially.  We have to trunc the destination
         *      address and round the copy size or we'll end up
         *      splitting entries in strange ways.
         */

        if (!VM_MAP_PAGE_ALIGNED(copy->size,
            VM_MAP_PAGE_MASK(dst_map)) ||
            !VM_MAP_PAGE_ALIGNED(copy->offset,
            VM_MAP_PAGE_MASK(dst_map)) ||
            !VM_MAP_PAGE_ALIGNED(dst_addr,
            VM_MAP_PAGE_MASK(dst_map)) ||
            copy_page_shift != VM_MAP_PAGE_SHIFT(dst_map)) {
                aligned = FALSE;
                dst_end = vm_map_round_page(dst_addr + copy->size,
                    VM_MAP_PAGE_MASK(dst_map));
        } else {
                dst_end = dst_addr + copy->size;
        }

        vm_map_lock(dst_map);

        /* LP64todo - remove this check when vm_map_commpage64()
         * no longer has to stuff in a map_entry for the commpage
         * above the map's max_offset.
         */
        if (dst_addr >= dst_map->max_offset) {
                vm_map_unlock(dst_map);
                return KERN_INVALID_ADDRESS;
        }

start_pass_1:
        if (!vm_map_lookup_entry(dst_map, dst_addr, &tmp_entry)) {
                vm_map_unlock(dst_map);
                return KERN_INVALID_ADDRESS;
        }
        vm_map_clip_start(dst_map,
            tmp_entry,
            vm_map_trunc_page(dst_addr,
            VM_MAP_PAGE_MASK(dst_map)));
        for (entry = tmp_entry;;) {
                vm_map_entry_t  next = entry->vme_next;

                while (entry->is_sub_map) {
                        vm_map_offset_t sub_start;
                        vm_map_offset_t sub_end;
                        vm_map_offset_t local_end;

                        if (entry->in_transition) {
                                /*
                                 * Say that we are waiting, and wait for entry.
                                 */
                                entry->needs_wakeup = TRUE;
                                vm_map_entry_wait(dst_map, THREAD_UNINT);

                                goto start_pass_1;
                        }

                        local_end = entry->vme_end;
                        if (!(entry->needs_copy)) {
                                /* if needs_copy we are a COW submap */
                                /* in such a case we just replace so */
                                /* there is no need for the follow-  */
                                /* ing check.                        */
                                encountered_sub_map = TRUE;
                                sub_start = VME_OFFSET(entry);

                                if (entry->vme_end < dst_end) {
                                        sub_end = entry->vme_end;
                                } else {
                                        sub_end = dst_end;
                                }
                                sub_end -= entry->vme_start;
                                sub_end += VME_OFFSET(entry);
                                vm_map_unlock(dst_map);

                                kr = vm_map_overwrite_submap_recurse(
                                        VME_SUBMAP(entry),
                                        sub_start,
                                        sub_end - sub_start);
                                if (kr != KERN_SUCCESS) {
                                        return kr;
                                }
                                vm_map_lock(dst_map);
                        }

                        if (dst_end <= entry->vme_end) {
                                goto start_overwrite;
                        }
                        if (!vm_map_lookup_entry(dst_map, local_end,
                            &entry)) {
                                vm_map_unlock(dst_map);
                                return KERN_INVALID_ADDRESS;
                        }
                        next = entry->vme_next;
                }

                if (!(entry->protection & VM_PROT_WRITE)) {
                        vm_map_unlock(dst_map);
                        return KERN_PROTECTION_FAILURE;
                }

                /*
                 *      If the entry is in transition, we must wait
                 *      for it to exit that state.  Anything could happen
                 *      when we unlock the map, so start over.
                 */
                if (entry->in_transition) {
                        /*
                         * Say that we are waiting, and wait for entry.
                         */
                        entry->needs_wakeup = TRUE;
                        vm_map_entry_wait(dst_map, THREAD_UNINT);

                        goto start_pass_1;
                }

/*
 *              our range is contained completely within this map entry
 */
                if (dst_end <= entry->vme_end) {
                        break;
                }
/*
 *              check that range specified is contiguous region
 */
                if ((next == vm_map_to_entry(dst_map)) ||
                    (next->vme_start != entry->vme_end)) {
                        vm_map_unlock(dst_map);
                        return KERN_INVALID_ADDRESS;
                }


                /*
                 *      Check for permanent objects in the destination.
                 */
                if ((VME_OBJECT(entry) != VM_OBJECT_NULL) &&
                    ((!VME_OBJECT(entry)->internal) ||
                    (VME_OBJECT(entry)->true_share))) {
                        contains_permanent_objects = TRUE;
                }

                entry = next;
        }/* for */

start_overwrite:
        /*
         *      If there are permanent objects in the destination, then
         *      the copy cannot be interrupted.
         */

        if (interruptible && contains_permanent_objects) {
                vm_map_unlock(dst_map);
                return KERN_FAILURE;   /* XXX */
        }

        /*
         *
         *      Make a second pass, overwriting the data
         *      At the beginning of each loop iteration,
         *      the next entry to be overwritten is "tmp_entry"
         *      (initially, the value returned from the lookup above),
         *      and the starting address expected in that entry
         *      is "start".
         */

        total_size = copy->size;
        if (encountered_sub_map) {
                copy_size = 0;
                /* re-calculate tmp_entry since we've had the map */
                /* unlocked */
                if (!vm_map_lookup_entry( dst_map, dst_addr, &tmp_entry)) {
                        vm_map_unlock(dst_map);
                        return KERN_INVALID_ADDRESS;
                }
        } else {
                copy_size = copy->size;
        }

        base_addr = dst_addr;
        while (TRUE) {
                /* deconstruct the copy object and do in parts */
                /* only in sub_map, interruptable case */
                vm_map_entry_t  copy_entry;
                vm_map_entry_t  previous_prev = VM_MAP_ENTRY_NULL;
                vm_map_entry_t  next_copy = VM_MAP_ENTRY_NULL;
                int             nentries;
                int             remaining_entries = 0;
                vm_map_offset_t new_offset = 0;

                for (entry = tmp_entry; copy_size == 0;) {
                        vm_map_entry_t  next;

                        next = entry->vme_next;

                        /* tmp_entry and base address are moved along */
                        /* each time we encounter a sub-map.  Otherwise */
                        /* entry can outpase tmp_entry, and the copy_size */
                        /* may reflect the distance between them */
                        /* if the current entry is found to be in transition */
                        /* we will start over at the beginning or the last */
                        /* encounter of a submap as dictated by base_addr */
                        /* we will zero copy_size accordingly. */
                        if (entry->in_transition) {
                                /*
                                 * Say that we are waiting, and wait for entry.
                                 */
                                entry->needs_wakeup = TRUE;
                                vm_map_entry_wait(dst_map, THREAD_UNINT);

                                if (!vm_map_lookup_entry(dst_map, base_addr,
                                    &tmp_entry)) {
                                        vm_map_unlock(dst_map);
                                        return KERN_INVALID_ADDRESS;
                                }
                                copy_size = 0;
                                entry = tmp_entry;
                                continue;
                        }
                        if (entry->is_sub_map) {
                                vm_map_offset_t sub_start;
                                vm_map_offset_t sub_end;
                                vm_map_offset_t local_end;

                                if (entry->needs_copy) {
                                        /* if this is a COW submap */
                                        /* just back the range with a */
                                        /* anonymous entry */
                                        if (entry->vme_end < dst_end) {
                                                sub_end = entry->vme_end;
                                        } else {
                                                sub_end = dst_end;
                                        }
                                        if (entry->vme_start < base_addr) {
                                                sub_start = base_addr;
                                        } else {
                                                sub_start = entry->vme_start;
                                        }
                                        vm_map_clip_end(
                                                dst_map, entry, sub_end);
                                        vm_map_clip_start(
                                                dst_map, entry, sub_start);
                                        assert(!entry->use_pmap);
                                        assert(!entry->iokit_acct);
                                        entry->use_pmap = TRUE;
                                        entry->is_sub_map = FALSE;
                                        vm_map_deallocate(
                                                VME_SUBMAP(entry));
                                        VME_OBJECT_SET(entry, VM_OBJECT_NULL);
                                        VME_OFFSET_SET(entry, 0);
                                        entry->is_shared = FALSE;
                                        entry->needs_copy = FALSE;
                                        entry->protection = VM_PROT_DEFAULT;
                                        entry->max_protection = VM_PROT_ALL;
                                        entry->wired_count = 0;
                                        entry->user_wired_count = 0;
                                        if (entry->inheritance
                                            == VM_INHERIT_SHARE) {
                                                entry->inheritance = VM_INHERIT_COPY;
                                        }
                                        continue;
                                }
                                /* first take care of any non-sub_map */
                                /* entries to send */
                                if (base_addr < entry->vme_start) {
                                        /* stuff to send */
                                        copy_size =
                                            entry->vme_start - base_addr;
                                        break;
                                }
                                sub_start = VME_OFFSET(entry);

                                if (entry->vme_end < dst_end) {
                                        sub_end = entry->vme_end;
                                } else {
                                        sub_end = dst_end;
                                }
                                sub_end -= entry->vme_start;
                                sub_end += VME_OFFSET(entry);
                                local_end = entry->vme_end;
                                vm_map_unlock(dst_map);
                                copy_size = sub_end - sub_start;

                                /* adjust the copy object */
                                if (total_size > copy_size) {
                                        vm_map_size_t   local_size = 0;
                                        vm_map_size_t   entry_size;

                                        nentries = 1;
                                        new_offset = copy->offset;
                                        copy_entry = vm_map_copy_first_entry(copy);
                                        while (copy_entry !=
                                            vm_map_copy_to_entry(copy)) {
                                                entry_size = copy_entry->vme_end -
                                                    copy_entry->vme_start;
                                                if ((local_size < copy_size) &&
                                                    ((local_size + entry_size)
                                                    >= copy_size)) {
                                                        vm_map_copy_clip_end(copy,
                                                            copy_entry,
                                                            copy_entry->vme_start +
                                                            (copy_size - local_size));
                                                        entry_size = copy_entry->vme_end -
                                                            copy_entry->vme_start;
                                                        local_size += entry_size;
                                                        new_offset += entry_size;
                                                }
                                                if (local_size >= copy_size) {
                                                        next_copy = copy_entry->vme_next;
                                                        copy_entry->vme_next =
                                                            vm_map_copy_to_entry(copy);
                                                        previous_prev =
                                                            copy->cpy_hdr.links.prev;
                                                        copy->cpy_hdr.links.prev = copy_entry;
                                                        copy->size = copy_size;
                                                        remaining_entries =
                                                            copy->cpy_hdr.nentries;
                                                        remaining_entries -= nentries;
                                                        copy->cpy_hdr.nentries = nentries;
                                                        break;
                                                } else {
                                                        local_size += entry_size;
                                                        new_offset += entry_size;
                                                        nentries++;
                                                }
                                                copy_entry = copy_entry->vme_next;
                                        }
                                }

                                if ((entry->use_pmap) && (pmap == NULL)) {
                                        kr = vm_map_copy_overwrite_nested(
                                                VME_SUBMAP(entry),
                                                sub_start,
                                                copy,
                                                interruptible,
                                                VME_SUBMAP(entry)->pmap,
                                                TRUE);
                                } else if (pmap != NULL) {
                                        kr = vm_map_copy_overwrite_nested(
                                                VME_SUBMAP(entry),
                                                sub_start,
                                                copy,
                                                interruptible, pmap,
                                                TRUE);
                                } else {
                                        kr = vm_map_copy_overwrite_nested(
                                                VME_SUBMAP(entry),
                                                sub_start,
                                                copy,
                                                interruptible,
                                                dst_map->pmap,
                                                TRUE);
                                }
                                if (kr != KERN_SUCCESS) {
                                        if (next_copy != NULL) {
                                                copy->cpy_hdr.nentries +=
                                                    remaining_entries;
                                                copy->cpy_hdr.links.prev->vme_next =
                                                    next_copy;
                                                copy->cpy_hdr.links.prev
                                                        = previous_prev;
                                                copy->size = total_size;
                                        }
                                        return kr;
                                }
                                if (dst_end <= local_end) {
                                        return KERN_SUCCESS;
                                }
                                /* otherwise copy no longer exists, it was */
                                /* destroyed after successful copy_overwrite */
                                copy = vm_map_copy_allocate();
                                copy->type = VM_MAP_COPY_ENTRY_LIST;
                                copy->offset = new_offset;
                                copy->cpy_hdr.page_shift = copy_page_shift;

                                /*
                                 * XXX FBDP
                                 * this does not seem to deal with
                                 * the VM map store (R&B tree)
                                 */

                                total_size -= copy_size;
                                copy_size = 0;
                                /* put back remainder of copy in container */
                                if (next_copy != NULL) {
                                        copy->cpy_hdr.nentries = remaining_entries;
                                        copy->cpy_hdr.links.next = next_copy;
                                        copy->cpy_hdr.links.prev = previous_prev;
                                        copy->size = total_size;
                                        next_copy->vme_prev =
                                            vm_map_copy_to_entry(copy);
                                        next_copy = NULL;
                                }
                                base_addr = local_end;
                                vm_map_lock(dst_map);
                                if (!vm_map_lookup_entry(dst_map,
                                    local_end, &tmp_entry)) {
                                        vm_map_unlock(dst_map);
                                        return KERN_INVALID_ADDRESS;
                                }
                                entry = tmp_entry;
                                continue;
                        }
                        if (dst_end <= entry->vme_end) {
                                copy_size = dst_end - base_addr;
                                break;
                        }

                        if ((next == vm_map_to_entry(dst_map)) ||
                            (next->vme_start != entry->vme_end)) {
                                vm_map_unlock(dst_map);
                                return KERN_INVALID_ADDRESS;
                        }

                        entry = next;
                }/* for */

                next_copy = NULL;
                nentries = 1;

                /* adjust the copy object */
                if (total_size > copy_size) {
                        vm_map_size_t   local_size = 0;
                        vm_map_size_t   entry_size;

                        new_offset = copy->offset;
                        copy_entry = vm_map_copy_first_entry(copy);
                        while (copy_entry != vm_map_copy_to_entry(copy)) {
                                entry_size = copy_entry->vme_end -
                                    copy_entry->vme_start;
                                if ((local_size < copy_size) &&
                                    ((local_size + entry_size)
                                    >= copy_size)) {
                                        vm_map_copy_clip_end(copy, copy_entry,
                                            copy_entry->vme_start +
                                            (copy_size - local_size));
                                        entry_size = copy_entry->vme_end -
                                            copy_entry->vme_start;
                                        local_size += entry_size;
                                        new_offset += entry_size;
                                }
                                if (local_size >= copy_size) {
                                        next_copy = copy_entry->vme_next;
                                        copy_entry->vme_next =
                                            vm_map_copy_to_entry(copy);
                                        previous_prev =
                                            copy->cpy_hdr.links.prev;
                                        copy->cpy_hdr.links.prev = copy_entry;
                                        copy->size = copy_size;
                                        remaining_entries =
                                            copy->cpy_hdr.nentries;
                                        remaining_entries -= nentries;
                                        copy->cpy_hdr.nentries = nentries;
                                        break;
                                } else {
                                        local_size += entry_size;
                                        new_offset += entry_size;
                                        nentries++;
                                }
                                copy_entry = copy_entry->vme_next;
                        }
                }

                if (aligned) {
                        pmap_t  local_pmap;

                        if (pmap) {
                                local_pmap = pmap;
                        } else {
                                local_pmap = dst_map->pmap;
                        }

                        if ((kr =  vm_map_copy_overwrite_aligned(
                                    dst_map, tmp_entry, copy,
                                    base_addr, local_pmap)) != KERN_SUCCESS) {
                                if (next_copy != NULL) {
                                        copy->cpy_hdr.nentries +=
                                            remaining_entries;
                                        copy->cpy_hdr.links.prev->vme_next =
                                            next_copy;
                                        copy->cpy_hdr.links.prev =
                                            previous_prev;
                                        copy->size += copy_size;
                                }
                                return kr;
                        }
                        vm_map_unlock(dst_map);
                } else {
                        /*
                         * Performance gain:
                         *
                         * if the copy and dst address are misaligned but the same
                         * offset within the page we can copy_not_aligned the
                         * misaligned parts and copy aligned the rest.  If they are
                         * aligned but len is unaligned we simply need to copy
                         * the end bit unaligned.  We'll need to split the misaligned
                         * bits of the region in this case !
                         */
                        /* ALWAYS UNLOCKS THE dst_map MAP */
                        kr = vm_map_copy_overwrite_unaligned(
                                dst_map,
                                tmp_entry,
                                copy,
                                base_addr,
                                discard_on_success);
                        if (kr != KERN_SUCCESS) {
                                if (next_copy != NULL) {
                                        copy->cpy_hdr.nentries +=
                                            remaining_entries;
                                        copy->cpy_hdr.links.prev->vme_next =
                                            next_copy;
                                        copy->cpy_hdr.links.prev =
                                            previous_prev;
                                        copy->size += copy_size;
                                }
                                return kr;
                        }
                }
                total_size -= copy_size;
                if (total_size == 0) {
                        break;
                }
                base_addr += copy_size;
                copy_size = 0;
                copy->offset = new_offset;
                if (next_copy != NULL) {
                        copy->cpy_hdr.nentries = remaining_entries;
                        copy->cpy_hdr.links.next = next_copy;
                        copy->cpy_hdr.links.prev = previous_prev;
                        next_copy->vme_prev = vm_map_copy_to_entry(copy);
                        copy->size = total_size;
                }
                vm_map_lock(dst_map);
                while (TRUE) {
                        if (!vm_map_lookup_entry(dst_map,
                            base_addr, &tmp_entry)) {
                                vm_map_unlock(dst_map);
                                return KERN_INVALID_ADDRESS;
                        }
                        if (tmp_entry->in_transition) {
                                entry->needs_wakeup = TRUE;
                                vm_map_entry_wait(dst_map, THREAD_UNINT);
                        } else {
                                break;
                        }
                }
                vm_map_clip_start(dst_map,
                    tmp_entry,
                    vm_map_trunc_page(base_addr,
                    VM_MAP_PAGE_MASK(dst_map)));

                entry = tmp_entry;
        } /* while */

        /*
         *      Throw away the vm_map_copy object
         */
        if (discard_on_success) {
                vm_map_copy_discard(copy);
        }

        return KERN_SUCCESS;
}/* vm_map_copy_overwrite */

kern_return_t
vm_map_copy_overwrite(
        vm_map_t        dst_map,
        vm_map_offset_t dst_addr,
        vm_map_copy_t   copy,
        vm_map_size_t   copy_size,
        boolean_t       interruptible)
{
        vm_map_size_t   head_size, tail_size;
        vm_map_copy_t   head_copy, tail_copy;
        vm_map_offset_t head_addr, tail_addr;
        vm_map_entry_t  entry;
        kern_return_t   kr;
        vm_map_offset_t effective_page_mask, effective_page_size;
        int             copy_page_shift;

        head_size = 0;
        tail_size = 0;
        head_copy = NULL;
        tail_copy = NULL;
        head_addr = 0;
        tail_addr = 0;

        if (interruptible ||
            copy == VM_MAP_COPY_NULL ||
            copy->type != VM_MAP_COPY_ENTRY_LIST) {
                /*
                 * We can't split the "copy" map if we're interruptible
                 * or if we don't have a "copy" map...
                 */
blunt_copy:
                return vm_map_copy_overwrite_nested(dst_map,
                           dst_addr,
                           copy,
                           interruptible,
                           (pmap_t) NULL,
                           TRUE);
        }

        copy_page_shift = VM_MAP_COPY_PAGE_SHIFT(copy);
        if (copy_page_shift < PAGE_SHIFT ||
            VM_MAP_PAGE_SHIFT(dst_map) < PAGE_SHIFT) {
                goto blunt_copy;
        }

        if (VM_MAP_PAGE_SHIFT(dst_map) < PAGE_SHIFT) {
                effective_page_mask = VM_MAP_PAGE_MASK(dst_map);
        } else {
                effective_page_mask = MAX(VM_MAP_PAGE_MASK(dst_map), PAGE_MASK);
                effective_page_mask = MAX(VM_MAP_COPY_PAGE_MASK(copy),
                    effective_page_mask);
        }
        effective_page_size = effective_page_mask + 1;

        if (copy_size < VM_MAP_COPY_OVERWRITE_OPTIMIZATION_THRESHOLD_PAGES * effective_page_size) {
                /*
                 * Too small to bother with optimizing...
                 */
                goto blunt_copy;
        }

        if ((dst_addr & effective_page_mask) !=
            (copy->offset & effective_page_mask)) {
                /*
                 * Incompatible mis-alignment of source and destination...
                 */
                goto blunt_copy;
        }

        /*
         * Proper alignment or identical mis-alignment at the beginning.
         * Let's try and do a small unaligned copy first (if needed)
         * and then an aligned copy for the rest.
         */
        if (!vm_map_page_aligned(dst_addr, effective_page_mask)) {
                head_addr = dst_addr;
                head_size = (effective_page_size -
                    (copy->offset & effective_page_mask));
                head_size = MIN(head_size, copy_size);
        }
        if (!vm_map_page_aligned(copy->offset + copy_size,
            effective_page_mask)) {
                /*
                 * Mis-alignment at the end.
                 * Do an aligned copy up to the last page and
                 * then an unaligned copy for the remaining bytes.
                 */
                tail_size = ((copy->offset + copy_size) &
                    effective_page_mask);
                tail_size = MIN(tail_size, copy_size);
                tail_addr = dst_addr + copy_size - tail_size;
                assert(tail_addr >= head_addr + head_size);
        }
        assert(head_size + tail_size <= copy_size);

        if (head_size + tail_size == copy_size) {
                /*
                 * It's all unaligned, no optimization possible...
                 */
                goto blunt_copy;
        }

        /*
         * Can't optimize if there are any submaps in the
         * destination due to the way we free the "copy" map
         * progressively in vm_map_copy_overwrite_nested()
         * in that case.
         */
        vm_map_lock_read(dst_map);
        if (!vm_map_lookup_entry(dst_map, dst_addr, &entry)) {
                vm_map_unlock_read(dst_map);
                goto blunt_copy;
        }
        for (;
            (entry != vm_map_copy_to_entry(copy) &&
            entry->vme_start < dst_addr + copy_size);
            entry = entry->vme_next) {
                if (entry->is_sub_map) {
                        vm_map_unlock_read(dst_map);
                        goto blunt_copy;
                }
        }
        vm_map_unlock_read(dst_map);

        if (head_size) {
                /*
                 * Unaligned copy of the first "head_size" bytes, to reach
                 * a page boundary.
                 */

                /*
                 * Extract "head_copy" out of "copy".
                 */
                head_copy = vm_map_copy_allocate();
                head_copy->type = VM_MAP_COPY_ENTRY_LIST;
                head_copy->cpy_hdr.entries_pageable =
                    copy->cpy_hdr.entries_pageable;
                vm_map_store_init(&head_copy->cpy_hdr);
                head_copy->cpy_hdr.page_shift = copy_page_shift;

                entry = vm_map_copy_first_entry(copy);
                if (entry->vme_end < copy->offset + head_size) {
                        head_size = entry->vme_end - copy->offset;
                }

                head_copy->offset = copy->offset;
                head_copy->size = head_size;
                copy->offset += head_size;
                copy->size -= head_size;
                copy_size -= head_size;
                assert(copy_size > 0);

                vm_map_copy_clip_end(copy, entry, copy->offset);
                vm_map_copy_entry_unlink(copy, entry);
                vm_map_copy_entry_link(head_copy,
                    vm_map_copy_to_entry(head_copy),
                    entry);

                /*
                 * Do the unaligned copy.
                 */
                kr = vm_map_copy_overwrite_nested(dst_map,
                    head_addr,
                    head_copy,
                    interruptible,
                    (pmap_t) NULL,
                    FALSE);
                if (kr != KERN_SUCCESS) {
                        goto done;
                }
        }

        if (tail_size) {
                /*
                 * Extract "tail_copy" out of "copy".
                 */
                tail_copy = vm_map_copy_allocate();
                tail_copy->type = VM_MAP_COPY_ENTRY_LIST;
                tail_copy->cpy_hdr.entries_pageable =
                    copy->cpy_hdr.entries_pageable;
                vm_map_store_init(&tail_copy->cpy_hdr);
                tail_copy->cpy_hdr.page_shift = copy_page_shift;

                tail_copy->offset = copy->offset + copy_size - tail_size;
                tail_copy->size = tail_size;

                copy->size -= tail_size;
                copy_size -= tail_size;
                assert(copy_size > 0);

                entry = vm_map_copy_last_entry(copy);
                vm_map_copy_clip_start(copy, entry, tail_copy->offset);
                entry = vm_map_copy_last_entry(copy);
                vm_map_copy_entry_unlink(copy, entry);
                vm_map_copy_entry_link(tail_copy,
                    vm_map_copy_last_entry(tail_copy),
                    entry);
        }

        /*
         * If we are here from ipc_kmsg_copyout_ool_descriptor(),
         * we want to avoid TOCTOU issues w.r.t copy->size but
         * we don't need to change vm_map_copy_overwrite_nested()
         * and all other vm_map_copy_overwrite variants.
         *
         * So we assign the original copy_size that was passed into
         * this routine back to copy.
         *
         * This use of local 'copy_size' passed into this routine is
         * to try and protect against TOCTOU attacks where the kernel
         * has been exploited. We don't expect this to be an issue
         * during normal system operation.
         */
        assertf(copy->size == copy_size,
            "Mismatch of copy sizes. Expected 0x%llx, Got 0x%llx\n", (uint64_t) copy_size, (uint64_t) copy->size);
        copy->size = copy_size;

        /*
         * Copy most (or possibly all) of the data.
         */
        kr = vm_map_copy_overwrite_nested(dst_map,
            dst_addr + head_size,
            copy,
            interruptible,
            (pmap_t) NULL,
            FALSE);
        if (kr != KERN_SUCCESS) {
                goto done;
        }

        if (tail_size) {
                kr = vm_map_copy_overwrite_nested(dst_map,
                    tail_addr,
                    tail_copy,
                    interruptible,
                    (pmap_t) NULL,
                    FALSE);
        }

done:
        assert(copy->type == VM_MAP_COPY_ENTRY_LIST);
        if (kr == KERN_SUCCESS) {
                /*
                 * Discard all the copy maps.
                 */
                if (head_copy) {
                        vm_map_copy_discard(head_copy);
                        head_copy = NULL;
                }
                vm_map_copy_discard(copy);
                if (tail_copy) {
                        vm_map_copy_discard(tail_copy);
                        tail_copy = NULL;
                }
        } else {
                /*
                 * Re-assemble the original copy map.
                 */
                if (head_copy) {
                        entry = vm_map_copy_first_entry(head_copy);
                        vm_map_copy_entry_unlink(head_copy, entry);
                        vm_map_copy_entry_link(copy,
                            vm_map_copy_to_entry(copy),
                            entry);
                        copy->offset -= head_size;
                        copy->size += head_size;
                        vm_map_copy_discard(head_copy);
                        head_copy = NULL;
                }
                if (tail_copy) {
                        entry = vm_map_copy_last_entry(tail_copy);
                        vm_map_copy_entry_unlink(tail_copy, entry);
                        vm_map_copy_entry_link(copy,
                            vm_map_copy_last_entry(copy),
                            entry);
                        copy->size += tail_size;
                        vm_map_copy_discard(tail_copy);
                        tail_copy = NULL;
                }
        }
        return kr;
}


/*
 *      Routine: vm_map_copy_overwrite_unaligned        [internal use only]
 *
 *      Decription:
 *      Physically copy unaligned data
 *
 *      Implementation:
 *      Unaligned parts of pages have to be physically copied.  We use
 *      a modified form of vm_fault_copy (which understands none-aligned
 *      page offsets and sizes) to do the copy.  We attempt to copy as
 *      much memory in one go as possibly, however vm_fault_copy copies
 *      within 1 memory object so we have to find the smaller of "amount left"
 *      "source object data size" and "target object data size".  With
 *      unaligned data we don't need to split regions, therefore the source
 *      (copy) object should be one map entry, the target range may be split
 *      over multiple map entries however.  In any event we are pessimistic
 *      about these assumptions.
 *
 *      Assumptions:
 *      dst_map is locked on entry and is return locked on success,
 *      unlocked on error.
 */

static kern_return_t
vm_map_copy_overwrite_unaligned(
        vm_map_t        dst_map,
        vm_map_entry_t  entry,
        vm_map_copy_t   copy,
        vm_map_offset_t start,
        boolean_t       discard_on_success)
{
        vm_map_entry_t          copy_entry;
        vm_map_entry_t          copy_entry_next;
        vm_map_version_t        version;
        vm_object_t             dst_object;
        vm_object_offset_t      dst_offset;
        vm_object_offset_t      src_offset;
        vm_object_offset_t      entry_offset;
        vm_map_offset_t         entry_end;
        vm_map_size_t           src_size,
            dst_size,
            copy_size,
            amount_left;
        kern_return_t           kr = KERN_SUCCESS;


        copy_entry = vm_map_copy_first_entry(copy);

        vm_map_lock_write_to_read(dst_map);

        src_offset = copy->offset - trunc_page_mask_64(copy->offset, VM_MAP_COPY_PAGE_MASK(copy));
        amount_left = copy->size;
/*
 *      unaligned so we never clipped this entry, we need the offset into
 *      the vm_object not just the data.
 */
        while (amount_left > 0) {
                if (entry == vm_map_to_entry(dst_map)) {
                        vm_map_unlock_read(dst_map);
                        return KERN_INVALID_ADDRESS;
                }

                /* "start" must be within the current map entry */
                assert((start >= entry->vme_start) && (start < entry->vme_end));

                dst_offset = start - entry->vme_start;

                dst_size = entry->vme_end - start;

                src_size = copy_entry->vme_end -
                    (copy_entry->vme_start + src_offset);

                if (dst_size < src_size) {
/*
 *                      we can only copy dst_size bytes before
 *                      we have to get the next destination entry
 */
                        copy_size = dst_size;
                } else {
/*
 *                      we can only copy src_size bytes before
 *                      we have to get the next source copy entry
 */
                        copy_size = src_size;
                }

                if (copy_size > amount_left) {
                        copy_size = amount_left;
                }
/*
 *              Entry needs copy, create a shadow shadow object for
 *              Copy on write region.
 */
                if (entry->needs_copy &&
                    ((entry->protection & VM_PROT_WRITE) != 0)) {
                        if (vm_map_lock_read_to_write(dst_map)) {
                                vm_map_lock_read(dst_map);
                                goto RetryLookup;
                        }
                        VME_OBJECT_SHADOW(entry,
                            (vm_map_size_t)(entry->vme_end
                            - entry->vme_start));
                        entry->needs_copy = FALSE;
                        vm_map_lock_write_to_read(dst_map);
                }
                dst_object = VME_OBJECT(entry);
/*
 *              unlike with the virtual (aligned) copy we're going
 *              to fault on it therefore we need a target object.
 */
                if (dst_object == VM_OBJECT_NULL) {
                        if (vm_map_lock_read_to_write(dst_map)) {
                                vm_map_lock_read(dst_map);
                                goto RetryLookup;
                        }
                        dst_object = vm_object_allocate((vm_map_size_t)
                            entry->vme_end - entry->vme_start);
                        VME_OBJECT_SET(entry, dst_object);
                        VME_OFFSET_SET(entry, 0);
                        assert(entry->use_pmap);
                        vm_map_lock_write_to_read(dst_map);
                }
/*
 *              Take an object reference and unlock map. The "entry" may
 *              disappear or change when the map is unlocked.
 */
                vm_object_reference(dst_object);
                version.main_timestamp = dst_map->timestamp;
                entry_offset = VME_OFFSET(entry);
                entry_end = entry->vme_end;
                vm_map_unlock_read(dst_map);
/*
 *              Copy as much as possible in one pass
 */
                kr = vm_fault_copy(
                        VME_OBJECT(copy_entry),
                        VME_OFFSET(copy_entry) + src_offset,
                        &copy_size,
                        dst_object,
                        entry_offset + dst_offset,
                        dst_map,
                        &version,
                        THREAD_UNINT );

                start += copy_size;
                src_offset += copy_size;
                amount_left -= copy_size;
/*
 *              Release the object reference
 */
                vm_object_deallocate(dst_object);
/*
 *              If a hard error occurred, return it now
 */
                if (kr != KERN_SUCCESS) {
                        return kr;
                }

                if ((copy_entry->vme_start + src_offset) == copy_entry->vme_end
                    || amount_left == 0) {
/*
 *                      all done with this copy entry, dispose.
 */
                        copy_entry_next = copy_entry->vme_next;

                        if (discard_on_success) {
                                vm_map_copy_entry_unlink(copy, copy_entry);
                                assert(!copy_entry->is_sub_map);
                                vm_object_deallocate(VME_OBJECT(copy_entry));
                                vm_map_copy_entry_dispose(copy, copy_entry);
                        }

                        if (copy_entry_next == vm_map_copy_to_entry(copy) &&
                            amount_left) {
/*
 *                              not finished copying but run out of source
 */
                                return KERN_INVALID_ADDRESS;
                        }

                        copy_entry = copy_entry_next;

                        src_offset = 0;
                }

                if (amount_left == 0) {
                        return KERN_SUCCESS;
                }

                vm_map_lock_read(dst_map);
                if (version.main_timestamp == dst_map->timestamp) {
                        if (start == entry_end) {
/*
 *                              destination region is split.  Use the version
 *                              information to avoid a lookup in the normal
 *                              case.
 */
                                entry = entry->vme_next;
/*
 *                              should be contiguous. Fail if we encounter
 *                              a hole in the destination.
 */
                                if (start != entry->vme_start) {
                                        vm_map_unlock_read(dst_map);
                                        return KERN_INVALID_ADDRESS;
                                }
                        }
                } else {
/*
 *                      Map version check failed.
 *                      we must lookup the entry because somebody
 *                      might have changed the map behind our backs.
 */
RetryLookup:
                        if (!vm_map_lookup_entry(dst_map, start, &entry)) {
                                vm_map_unlock_read(dst_map);
                                return KERN_INVALID_ADDRESS;
                        }
                }
        }/* while */

        return KERN_SUCCESS;
}/* vm_map_copy_overwrite_unaligned */

/*
 *      Routine: vm_map_copy_overwrite_aligned  [internal use only]
 *
 *      Description:
 *      Does all the vm_trickery possible for whole pages.
 *
 *      Implementation:
 *
 *      If there are no permanent objects in the destination,
 *      and the source and destination map entry zones match,
 *      and the destination map entry is not shared,
 *      then the map entries can be deleted and replaced
 *      with those from the copy.  The following code is the
 *      basic idea of what to do, but there are lots of annoying
 *      little details about getting protection and inheritance
 *      right.  Should add protection, inheritance, and sharing checks
 *      to the above pass and make sure that no wiring is involved.
 */

int vm_map_copy_overwrite_aligned_src_not_internal = 0;
int vm_map_copy_overwrite_aligned_src_not_symmetric = 0;
int vm_map_copy_overwrite_aligned_src_large = 0;

static kern_return_t
vm_map_copy_overwrite_aligned(
        vm_map_t        dst_map,
        vm_map_entry_t  tmp_entry,
        vm_map_copy_t   copy,
        vm_map_offset_t start,
        __unused pmap_t pmap)
{
        vm_object_t     object;
        vm_map_entry_t  copy_entry;
        vm_map_size_t   copy_size;
        vm_map_size_t   size;
        vm_map_entry_t  entry;

        while ((copy_entry = vm_map_copy_first_entry(copy))
            != vm_map_copy_to_entry(copy)) {
                copy_size = (copy_entry->vme_end - copy_entry->vme_start);

                entry = tmp_entry;
                if (entry->is_sub_map) {
                        /* unnested when clipped earlier */
                        assert(!entry->use_pmap);
                }
                if (entry == vm_map_to_entry(dst_map)) {
                        vm_map_unlock(dst_map);
                        return KERN_INVALID_ADDRESS;
                }
                size = (entry->vme_end - entry->vme_start);
                /*
                 *      Make sure that no holes popped up in the
                 *      address map, and that the protection is
                 *      still valid, in case the map was unlocked
                 *      earlier.
                 */

                if ((entry->vme_start != start) || ((entry->is_sub_map)
                    && !entry->needs_copy)) {
                        vm_map_unlock(dst_map);
                        return KERN_INVALID_ADDRESS;
                }
                assert(entry != vm_map_to_entry(dst_map));

                /*
                 *      Check protection again
                 */

                if (!(entry->protection & VM_PROT_WRITE)) {
                        vm_map_unlock(dst_map);
                        return KERN_PROTECTION_FAILURE;
                }

                /*
                 *      Adjust to source size first
                 */

                if (copy_size < size) {
                        if (entry->map_aligned &&
                            !VM_MAP_PAGE_ALIGNED(entry->vme_start + copy_size,
                            VM_MAP_PAGE_MASK(dst_map))) {
                                /* no longer map-aligned */
                                entry->map_aligned = FALSE;
                        }
                        vm_map_clip_end(dst_map, entry, entry->vme_start + copy_size);
                        size = copy_size;
                }

                /*
                 *      Adjust to destination size
                 */

                if (size < copy_size) {
                        vm_map_copy_clip_end(copy, copy_entry,
                            copy_entry->vme_start + size);
                        copy_size = size;
                }

                assert((entry->vme_end - entry->vme_start) == size);
                assert((tmp_entry->vme_end - tmp_entry->vme_start) == size);
                assert((copy_entry->vme_end - copy_entry->vme_start) == size);

                /*
                 *      If the destination contains temporary unshared memory,
                 *      we can perform the copy by throwing it away and
                 *      installing the source data.
                 */

                object = VME_OBJECT(entry);
                if ((!entry->is_shared &&
                    ((object == VM_OBJECT_NULL) ||
                    (object->internal && !object->true_share))) ||
                    entry->needs_copy) {
                        vm_object_t     old_object = VME_OBJECT(entry);
                        vm_object_offset_t      old_offset = VME_OFFSET(entry);
                        vm_object_offset_t      offset;

                        /*
                         * Ensure that the source and destination aren't
                         * identical
                         */
                        if (old_object == VME_OBJECT(copy_entry) &&
                            old_offset == VME_OFFSET(copy_entry)) {
                                vm_map_copy_entry_unlink(copy, copy_entry);
                                vm_map_copy_entry_dispose(copy, copy_entry);

                                if (old_object != VM_OBJECT_NULL) {
                                        vm_object_deallocate(old_object);
                                }

                                start = tmp_entry->vme_end;
                                tmp_entry = tmp_entry->vme_next;
                                continue;
                        }

#if XNU_TARGET_OS_OSX
#define __TRADEOFF1_OBJ_SIZE (64 * 1024 * 1024) /* 64 MB */
#define __TRADEOFF1_COPY_SIZE (128 * 1024)      /* 128 KB */
                        if (VME_OBJECT(copy_entry) != VM_OBJECT_NULL &&
                            VME_OBJECT(copy_entry)->vo_size >= __TRADEOFF1_OBJ_SIZE &&
                            copy_size <= __TRADEOFF1_COPY_SIZE) {
                                /*
                                 * Virtual vs. Physical copy tradeoff #1.
                                 *
                                 * Copying only a few pages out of a large
                                 * object:  do a physical copy instead of
                                 * a virtual copy, to avoid possibly keeping
                                 * the entire large object alive because of
                                 * those few copy-on-write pages.
                                 */
                                vm_map_copy_overwrite_aligned_src_large++;
                                goto slow_copy;
                        }
#endif /* XNU_TARGET_OS_OSX */

                        if ((dst_map->pmap != kernel_pmap) &&
                            (VME_ALIAS(entry) >= VM_MEMORY_MALLOC) &&
                            (VME_ALIAS(entry) <= VM_MEMORY_MALLOC_MEDIUM)) {
                                vm_object_t new_object, new_shadow;

                                /*
                                 * We're about to map something over a mapping
                                 * established by malloc()...
                                 */
                                new_object = VME_OBJECT(copy_entry);
                                if (new_object != VM_OBJECT_NULL) {
                                        vm_object_lock_shared(new_object);
                                }
                                while (new_object != VM_OBJECT_NULL &&
#if XNU_TARGET_OS_OSX
                                    !new_object->true_share &&
                                    new_object->copy_strategy == MEMORY_OBJECT_COPY_SYMMETRIC &&
#endif /* XNU_TARGET_OS_OSX */
                                    new_object->internal) {
                                        new_shadow = new_object->shadow;
                                        if (new_shadow == VM_OBJECT_NULL) {
                                                break;
                                        }
                                        vm_object_lock_shared(new_shadow);
                                        vm_object_unlock(new_object);
                                        new_object = new_shadow;
                                }
                                if (new_object != VM_OBJECT_NULL) {
                                        if (!new_object->internal) {
                                                /*
                                                 * The new mapping is backed
                                                 * by an external object.  We
                                                 * don't want malloc'ed memory
                                                 * to be replaced with such a
                                                 * non-anonymous mapping, so
                                                 * let's go off the optimized
                                                 * path...
                                                 */
                                                vm_map_copy_overwrite_aligned_src_not_internal++;
                                                vm_object_unlock(new_object);
                                                goto slow_copy;
                                        }
#if XNU_TARGET_OS_OSX
                                        if (new_object->true_share ||
                                            new_object->copy_strategy != MEMORY_OBJECT_COPY_SYMMETRIC) {
                                                /*
                                                 * Same if there's a "true_share"
                                                 * object in the shadow chain, or
                                                 * an object with a non-default
                                                 * (SYMMETRIC) copy strategy.
                                                 */
                                                vm_map_copy_overwrite_aligned_src_not_symmetric++;
                                                vm_object_unlock(new_object);
                                                goto slow_copy;
                                        }
#endif /* XNU_TARGET_OS_OSX */
                                        vm_object_unlock(new_object);
                                }
                                /*
                                 * The new mapping is still backed by
                                 * anonymous (internal) memory, so it's
                                 * OK to substitute it for the original
                                 * malloc() mapping.
                                 */
                        }

                        if (old_object != VM_OBJECT_NULL) {
                                if (entry->is_sub_map) {
                                        if (entry->use_pmap) {
#ifndef NO_NESTED_PMAP
                                                pmap_unnest(dst_map->pmap,
                                                    (addr64_t)entry->vme_start,
                                                    entry->vme_end - entry->vme_start);
#endif  /* NO_NESTED_PMAP */
                                                if (dst_map->mapped_in_other_pmaps) {
                                                        /* clean up parent */
                                                        /* map/maps */
                                                        vm_map_submap_pmap_clean(
                                                                dst_map, entry->vme_start,
                                                                entry->vme_end,
                                                                VME_SUBMAP(entry),
                                                                VME_OFFSET(entry));
                                                }
                                        } else {
                                                vm_map_submap_pmap_clean(
                                                        dst_map, entry->vme_start,
                                                        entry->vme_end,
                                                        VME_SUBMAP(entry),
                                                        VME_OFFSET(entry));
                                        }
                                        vm_map_deallocate(VME_SUBMAP(entry));
                                } else {
                                        if (dst_map->mapped_in_other_pmaps) {
                                                vm_object_pmap_protect_options(
                                                        VME_OBJECT(entry),
                                                        VME_OFFSET(entry),
                                                        entry->vme_end
                                                        - entry->vme_start,
                                                        PMAP_NULL,
                                                        PAGE_SIZE,
                                                        entry->vme_start,
                                                        VM_PROT_NONE,
                                                        PMAP_OPTIONS_REMOVE);
                                        } else {
                                                pmap_remove_options(
                                                        dst_map->pmap,
                                                        (addr64_t)(entry->vme_start),
                                                        (addr64_t)(entry->vme_end),
                                                        PMAP_OPTIONS_REMOVE);
                                        }
                                        vm_object_deallocate(old_object);
                                }
                        }

                        if (entry->iokit_acct) {
                                /* keep using iokit accounting */
                                entry->use_pmap = FALSE;
                        } else {
                                /* use pmap accounting */
                                entry->use_pmap = TRUE;
                        }
                        entry->is_sub_map = FALSE;
                        VME_OBJECT_SET(entry, VME_OBJECT(copy_entry));
                        object = VME_OBJECT(entry);
                        entry->needs_copy = copy_entry->needs_copy;
                        entry->wired_count = 0;
                        entry->user_wired_count = 0;
                        offset = VME_OFFSET(copy_entry);
                        VME_OFFSET_SET(entry, offset);

                        vm_map_copy_entry_unlink(copy, copy_entry);
                        vm_map_copy_entry_dispose(copy, copy_entry);

                        /*
                         * we could try to push pages into the pmap at this point, BUT
                         * this optimization only saved on average 2 us per page if ALL
                         * the pages in the source were currently mapped
                         * and ALL the pages in the dest were touched, if there were fewer
                         * than 2/3 of the pages touched, this optimization actually cost more cycles
                         * it also puts a lot of pressure on the pmap layer w/r to mapping structures
                         */

                        /*
                         *      Set up for the next iteration.  The map
                         *      has not been unlocked, so the next
                         *      address should be at the end of this
                         *      entry, and the next map entry should be
                         *      the one following it.
                         */

                        start = tmp_entry->vme_end;
                        tmp_entry = tmp_entry->vme_next;
                } else {
                        vm_map_version_t        version;
                        vm_object_t             dst_object;
                        vm_object_offset_t      dst_offset;
                        kern_return_t           r;

slow_copy:
                        if (entry->needs_copy) {
                                VME_OBJECT_SHADOW(entry,
                                    (entry->vme_end -
                                    entry->vme_start));
                                entry->needs_copy = FALSE;
                        }

                        dst_object = VME_OBJECT(entry);
                        dst_offset = VME_OFFSET(entry);

                        /*
                         *      Take an object reference, and record
                         *      the map version information so that the
                         *      map can be safely unlocked.
                         */

                        if (dst_object == VM_OBJECT_NULL) {
                                /*
                                 * We would usually have just taken the
                                 * optimized path above if the destination
                                 * object has not been allocated yet.  But we
                                 * now disable that optimization if the copy
                                 * entry's object is not backed by anonymous
                                 * memory to avoid replacing malloc'ed
                                 * (i.e. re-usable) anonymous memory with a
                                 * not-so-anonymous mapping.
                                 * So we have to handle this case here and
                                 * allocate a new VM object for this map entry.
                                 */
                                dst_object = vm_object_allocate(
                                        entry->vme_end - entry->vme_start);
                                dst_offset = 0;
                                VME_OBJECT_SET(entry, dst_object);
                                VME_OFFSET_SET(entry, dst_offset);
                                assert(entry->use_pmap);
                        }

                        vm_object_reference(dst_object);

                        /* account for unlock bumping up timestamp */
                        version.main_timestamp = dst_map->timestamp + 1;

                        vm_map_unlock(dst_map);

                        /*
                         *      Copy as much as possible in one pass
                         */

                        copy_size = size;
                        r = vm_fault_copy(
                                VME_OBJECT(copy_entry),
                                VME_OFFSET(copy_entry),
                                &copy_size,
                                dst_object,
                                dst_offset,
                                dst_map,
                                &version,
                                THREAD_UNINT );

                        /*
                         *      Release the object reference
                         */

                        vm_object_deallocate(dst_object);

                        /*
                         *      If a hard error occurred, return it now
                         */

                        if (r != KERN_SUCCESS) {
                                return r;
                        }

                        if (copy_size != 0) {
                                /*
                                 *      Dispose of the copied region
                                 */

                                vm_map_copy_clip_end(copy, copy_entry,
                                    copy_entry->vme_start + copy_size);
                                vm_map_copy_entry_unlink(copy, copy_entry);
                                vm_object_deallocate(VME_OBJECT(copy_entry));
                                vm_map_copy_entry_dispose(copy, copy_entry);
                        }

                        /*
                         *      Pick up in the destination map where we left off.
                         *
                         *      Use the version information to avoid a lookup
                         *      in the normal case.
                         */

                        start += copy_size;
                        vm_map_lock(dst_map);
                        if (version.main_timestamp == dst_map->timestamp &&
                            copy_size != 0) {
                                /* We can safely use saved tmp_entry value */

                                if (tmp_entry->map_aligned &&
                                    !VM_MAP_PAGE_ALIGNED(
                                            start,
                                            VM_MAP_PAGE_MASK(dst_map))) {
                                        /* no longer map-aligned */
                                        tmp_entry->map_aligned = FALSE;
                                }
                                vm_map_clip_end(dst_map, tmp_entry, start);
                                tmp_entry = tmp_entry->vme_next;
                        } else {
                                /* Must do lookup of tmp_entry */

                                if (!vm_map_lookup_entry(dst_map, start, &tmp_entry)) {
                                        vm_map_unlock(dst_map);
                                        return KERN_INVALID_ADDRESS;
                                }
                                if (tmp_entry->map_aligned &&
                                    !VM_MAP_PAGE_ALIGNED(
                                            start,
                                            VM_MAP_PAGE_MASK(dst_map))) {
                                        /* no longer map-aligned */
                                        tmp_entry->map_aligned = FALSE;
                                }
                                vm_map_clip_start(dst_map, tmp_entry, start);
                        }
                }
        }/* while */

        return KERN_SUCCESS;
}/* vm_map_copy_overwrite_aligned */

/*
 *      Routine: vm_map_copyin_kernel_buffer [internal use only]
 *
 *      Description:
 *              Copy in data to a kernel buffer from space in the
 *              source map. The original space may be optionally
 *              deallocated.
 *
 *              If successful, returns a new copy object.
 */
static kern_return_t
vm_map_copyin_kernel_buffer(
        vm_map_t        src_map,
        vm_map_offset_t src_addr,
        vm_map_size_t   len,
        boolean_t       src_destroy,
        vm_map_copy_t   *copy_result)
{
        kern_return_t kr;
        vm_map_copy_t copy;

        if (len > msg_ool_size_small) {
                return KERN_INVALID_ARGUMENT;
        }

        copy = zalloc_flags(vm_map_copy_zone, Z_WAITOK | Z_ZERO);
        if (copy == VM_MAP_COPY_NULL) {
                return KERN_RESOURCE_SHORTAGE;
        }
        copy->cpy_kdata = kheap_alloc(KHEAP_DATA_BUFFERS, len, Z_WAITOK);
        if (copy->cpy_kdata == NULL) {
                zfree(vm_map_copy_zone, copy);
                return KERN_RESOURCE_SHORTAGE;
        }

        copy->type = VM_MAP_COPY_KERNEL_BUFFER;
        copy->size = len;
        copy->offset = 0;

        kr = copyinmap(src_map, src_addr, copy->cpy_kdata, (vm_size_t)len);
        if (kr != KERN_SUCCESS) {
                kheap_free(KHEAP_DATA_BUFFERS, copy->cpy_kdata, len);
                zfree(vm_map_copy_zone, copy);
                return kr;
        }
        if (src_destroy) {
                (void) vm_map_remove(
                        src_map,
                        vm_map_trunc_page(src_addr,
                        VM_MAP_PAGE_MASK(src_map)),
                        vm_map_round_page(src_addr + len,
                        VM_MAP_PAGE_MASK(src_map)),
                        (VM_MAP_REMOVE_INTERRUPTIBLE |
                        VM_MAP_REMOVE_WAIT_FOR_KWIRE |
                        ((src_map == kernel_map) ? VM_MAP_REMOVE_KUNWIRE : VM_MAP_REMOVE_NO_FLAGS)));
        }
        *copy_result = copy;
        return KERN_SUCCESS;
}

/*
 *      Routine: vm_map_copyout_kernel_buffer   [internal use only]
 *
 *      Description:
 *              Copy out data from a kernel buffer into space in the
 *              destination map. The space may be otpionally dynamically
 *              allocated.
 *
 *              If successful, consumes the copy object.
 *              Otherwise, the caller is responsible for it.
 */
static int vm_map_copyout_kernel_buffer_failures = 0;
static kern_return_t
vm_map_copyout_kernel_buffer(
        vm_map_t                map,
        vm_map_address_t        *addr,  /* IN/OUT */
        vm_map_copy_t           copy,
        vm_map_size_t           copy_size,
        boolean_t               overwrite,
        boolean_t               consume_on_success)
{
        kern_return_t kr = KERN_SUCCESS;
        thread_t thread = current_thread();

        assert(copy->size == copy_size);

        /*
         * check for corrupted vm_map_copy structure
         */
        if (copy_size > msg_ool_size_small || copy->offset) {
                panic("Invalid vm_map_copy_t sz:%lld, ofst:%lld",
                    (long long)copy->size, (long long)copy->offset);
        }

        if (!overwrite) {
                /*
                 * Allocate space in the target map for the data
                 */
                *addr = 0;
                kr = vm_map_enter(map,
                    addr,
                    vm_map_round_page(copy_size,
                    VM_MAP_PAGE_MASK(map)),
                    (vm_map_offset_t) 0,
                    VM_FLAGS_ANYWHERE,
                    VM_MAP_KERNEL_FLAGS_NONE,
                    VM_KERN_MEMORY_NONE,
                    VM_OBJECT_NULL,
                    (vm_object_offset_t) 0,
                    FALSE,
                    VM_PROT_DEFAULT,
                    VM_PROT_ALL,
                    VM_INHERIT_DEFAULT);
                if (kr != KERN_SUCCESS) {
                        return kr;
                }
#if KASAN
                if (map->pmap == kernel_pmap) {
                        kasan_notify_address(*addr, copy->size);
                }
#endif
        }

        /*
         * Copyout the data from the kernel buffer to the target map.
         */
        if (thread->map == map) {
                /*
                 * If the target map is the current map, just do
                 * the copy.
                 */
                assert((vm_size_t)copy_size == copy_size);
                if (copyout(copy->cpy_kdata, *addr, (vm_size_t)copy_size)) {
                        kr = KERN_INVALID_ADDRESS;
                }
        } else {
                vm_map_t oldmap;

                /*
                 * If the target map is another map, assume the
                 * target's address space identity for the duration
                 * of the copy.
                 */
                vm_map_reference(map);
                oldmap = vm_map_switch(map);

                assert((vm_size_t)copy_size == copy_size);
                if (copyout(copy->cpy_kdata, *addr, (vm_size_t)copy_size)) {
                        vm_map_copyout_kernel_buffer_failures++;
                        kr = KERN_INVALID_ADDRESS;
                }

                (void) vm_map_switch(oldmap);
                vm_map_deallocate(map);
        }

        if (kr != KERN_SUCCESS) {
                /* the copy failed, clean up */
                if (!overwrite) {
                        /*
                         * Deallocate the space we allocated in the target map.
                         */
                        (void) vm_map_remove(
                                map,
                                vm_map_trunc_page(*addr,
                                VM_MAP_PAGE_MASK(map)),
                                vm_map_round_page((*addr +
                                vm_map_round_page(copy_size,
                                VM_MAP_PAGE_MASK(map))),
                                VM_MAP_PAGE_MASK(map)),
                                VM_MAP_REMOVE_NO_FLAGS);
                        *addr = 0;
                }
        } else {
                /* copy was successful, dicard the copy structure */
                if (consume_on_success) {
                        kheap_free(KHEAP_DATA_BUFFERS, copy->cpy_kdata, copy_size);
                        zfree(vm_map_copy_zone, copy);
                }
        }

        return kr;
}

/*
 *      Routine:        vm_map_copy_insert      [internal use only]
 *
 *      Description:
 *              Link a copy chain ("copy") into a map at the
 *              specified location (after "where").
 *      Side effects:
 *              The copy chain is destroyed.
 */
static void
vm_map_copy_insert(
        vm_map_t        map,
        vm_map_entry_t  after_where,
        vm_map_copy_t   copy)
{
        vm_map_entry_t  entry;

        while (vm_map_copy_first_entry(copy) != vm_map_copy_to_entry(copy)) {
                entry = vm_map_copy_first_entry(copy);
                vm_map_copy_entry_unlink(copy, entry);
                vm_map_store_entry_link(map, after_where, entry,
                    VM_MAP_KERNEL_FLAGS_NONE);
                after_where = entry;
        }
        zfree(vm_map_copy_zone, copy);
}

void
vm_map_copy_remap(
        vm_map_t        map,
        vm_map_entry_t  where,
        vm_map_copy_t   copy,
        vm_map_offset_t adjustment,
        vm_prot_t       cur_prot,
        vm_prot_t       max_prot,
        vm_inherit_t    inheritance)
{
        vm_map_entry_t  copy_entry, new_entry;

        for (copy_entry = vm_map_copy_first_entry(copy);
            copy_entry != vm_map_copy_to_entry(copy);
            copy_entry = copy_entry->vme_next) {
                /* get a new VM map entry for the map */
                new_entry = vm_map_entry_create(map,
                    !map->hdr.entries_pageable);
                /* copy the "copy entry" to the new entry */
                vm_map_entry_copy(map, new_entry, copy_entry);
                /* adjust "start" and "end" */
                new_entry->vme_start += adjustment;
                new_entry->vme_end += adjustment;
                /* clear some attributes */
                new_entry->inheritance = inheritance;
                new_entry->protection = cur_prot;
                new_entry->max_protection = max_prot;
                new_entry->behavior = VM_BEHAVIOR_DEFAULT;
                /* take an extra reference on the entry's "object" */
                if (new_entry->is_sub_map) {
                        assert(!new_entry->use_pmap); /* not nested */
                        vm_map_lock(VME_SUBMAP(new_entry));
                        vm_map_reference(VME_SUBMAP(new_entry));
                        vm_map_unlock(VME_SUBMAP(new_entry));
                } else {
                        vm_object_reference(VME_OBJECT(new_entry));
                }
                /* insert the new entry in the map */
                vm_map_store_entry_link(map, where, new_entry,
                    VM_MAP_KERNEL_FLAGS_NONE);
                /* continue inserting the "copy entries" after the new entry */
                where = new_entry;
        }
}


/*
 * Returns true if *size matches (or is in the range of) copy->size.
 * Upon returning true, the *size field is updated with the actual size of the
 * copy object (may be different for VM_MAP_COPY_ENTRY_LIST types)
 */
boolean_t
vm_map_copy_validate_size(
        vm_map_t                dst_map,
        vm_map_copy_t           copy,
        vm_map_size_t           *size)
{
        if (copy == VM_MAP_COPY_NULL) {
                return FALSE;
        }
        vm_map_size_t copy_sz = copy->size;
        vm_map_size_t sz = *size;
        switch (copy->type) {
        case VM_MAP_COPY_OBJECT:
        case VM_MAP_COPY_KERNEL_BUFFER:
                if (sz == copy_sz) {
                        return TRUE;
                }
                break;
        case VM_MAP_COPY_ENTRY_LIST:
                /*
                 * potential page-size rounding prevents us from exactly
                 * validating this flavor of vm_map_copy, but we can at least
                 * assert that it's within a range.
                 */
                if (copy_sz >= sz &&
                    copy_sz <= vm_map_round_page(sz, VM_MAP_PAGE_MASK(dst_map))) {
                        *size = copy_sz;
                        return TRUE;
                }
                break;
        default:
                break;
        }
        return FALSE;
}

/*
 *      Routine:        vm_map_copyout_size
 *
 *      Description:
 *              Copy out a copy chain ("copy") into newly-allocated
 *              space in the destination map. Uses a prevalidated
 *              size for the copy object (vm_map_copy_validate_size).
 *
 *              If successful, consumes the copy object.
 *              Otherwise, the caller is responsible for it.
 */
kern_return_t
vm_map_copyout_size(
        vm_map_t                dst_map,
        vm_map_address_t        *dst_addr,      /* OUT */
        vm_map_copy_t           copy,
        vm_map_size_t           copy_size)
{
        return vm_map_copyout_internal(dst_map, dst_addr, copy, copy_size,
                   TRUE,                     /* consume_on_success */
                   VM_PROT_DEFAULT,
                   VM_PROT_ALL,
                   VM_INHERIT_DEFAULT);
}

/*
 *      Routine:        vm_map_copyout
 *
 *      Description:
 *              Copy out a copy chain ("copy") into newly-allocated
 *              space in the destination map.
 *
 *              If successful, consumes the copy object.
 *              Otherwise, the caller is responsible for it.
 */
kern_return_t
vm_map_copyout(
        vm_map_t                dst_map,
        vm_map_address_t        *dst_addr,      /* OUT */
        vm_map_copy_t           copy)
{
        return vm_map_copyout_internal(dst_map, dst_addr, copy, copy ? copy->size : 0,
                   TRUE,                     /* consume_on_success */
                   VM_PROT_DEFAULT,
                   VM_PROT_ALL,
                   VM_INHERIT_DEFAULT);
}

kern_return_t
vm_map_copyout_internal(
        vm_map_t                dst_map,
        vm_map_address_t        *dst_addr,      /* OUT */
        vm_map_copy_t           copy,
        vm_map_size_t           copy_size,
        boolean_t               consume_on_success,
        vm_prot_t               cur_protection,
        vm_prot_t               max_protection,
        vm_inherit_t            inheritance)
{
        vm_map_size_t           size;
        vm_map_size_t           adjustment;
        vm_map_offset_t         start;
        vm_object_offset_t      vm_copy_start;
        vm_map_entry_t          last;
        vm_map_entry_t          entry;
        vm_map_entry_t          hole_entry;
        vm_map_copy_t           original_copy;

        /*
         *      Check for null copy object.
         */

        if (copy == VM_MAP_COPY_NULL) {
                *dst_addr = 0;
                return KERN_SUCCESS;
        }

        /*
         * Assert that the vm_map_copy is coming from the right
         * zone and hasn't been forged
         */
        vm_map_copy_require(copy);

        if (copy->size != copy_size) {
                *dst_addr = 0;
                return KERN_FAILURE;
        }

        /*
         *      Check for special copy object, created
         *      by vm_map_copyin_object.
         */

        if (copy->type == VM_MAP_COPY_OBJECT) {
                vm_object_t             object = copy->cpy_object;
                kern_return_t           kr;
                vm_object_offset_t      offset;

                offset = vm_object_trunc_page(copy->offset);
                size = vm_map_round_page((copy_size +
                    (vm_map_size_t)(copy->offset -
                    offset)),
                    VM_MAP_PAGE_MASK(dst_map));
                *dst_addr = 0;
                kr = vm_map_enter(dst_map, dst_addr, size,
                    (vm_map_offset_t) 0, VM_FLAGS_ANYWHERE,
                    VM_MAP_KERNEL_FLAGS_NONE,
                    VM_KERN_MEMORY_NONE,
                    object, offset, FALSE,
                    VM_PROT_DEFAULT, VM_PROT_ALL,
                    VM_INHERIT_DEFAULT);
                if (kr != KERN_SUCCESS) {
                        return kr;
                }
                /* Account for non-pagealigned copy object */
                *dst_addr += (vm_map_offset_t)(copy->offset - offset);
                if (consume_on_success) {
                        zfree(vm_map_copy_zone, copy);
                }
                return KERN_SUCCESS;
        }

        /*
         *      Check for special kernel buffer allocated
         *      by new_ipc_kmsg_copyin.
         */

        if (copy->type == VM_MAP_COPY_KERNEL_BUFFER) {
                return vm_map_copyout_kernel_buffer(dst_map, dst_addr,
                           copy, copy_size, FALSE,
                           consume_on_success);
        }

        original_copy = copy;
        if (copy->cpy_hdr.page_shift != VM_MAP_PAGE_SHIFT(dst_map)) {
                kern_return_t kr;
                vm_map_copy_t target_copy;
                vm_map_offset_t overmap_start, overmap_end, trimmed_start;

                target_copy = VM_MAP_COPY_NULL;
                DEBUG4K_ADJUST("adjusting...\n");
                kr = vm_map_copy_adjust_to_target(
                        copy,
                        0, /* offset */
                        copy->size, /* size */
                        dst_map,
                        TRUE, /* copy */
                        &target_copy,
                        &overmap_start,
                        &overmap_end,
                        &trimmed_start);
                if (kr != KERN_SUCCESS) {
                        DEBUG4K_COPY("adjust failed 0x%x\n", kr);
                        return kr;
                }
                DEBUG4K_COPY("copy %p (%d 0x%llx 0x%llx) dst_map %p (%d) target_copy %p (%d 0x%llx 0x%llx) overmap_start 0x%llx overmap_end 0x%llx trimmed_start 0x%llx\n", copy, copy->cpy_hdr.page_shift, copy->offset, (uint64_t)copy->size, dst_map, VM_MAP_PAGE_SHIFT(dst_map), target_copy, target_copy->cpy_hdr.page_shift, target_copy->offset, (uint64_t)target_copy->size, (uint64_t)overmap_start, (uint64_t)overmap_end, (uint64_t)trimmed_start);
                if (target_copy != copy) {
                        copy = target_copy;
                }
                copy_size = copy->size;
        }

        /*
         *      Find space for the data
         */

        vm_copy_start = vm_map_trunc_page((vm_map_size_t)copy->offset,
            VM_MAP_COPY_PAGE_MASK(copy));
        size = vm_map_round_page((vm_map_size_t)copy->offset + copy_size,
            VM_MAP_COPY_PAGE_MASK(copy))
            - vm_copy_start;


StartAgain:;

        vm_map_lock(dst_map);
        if (dst_map->disable_vmentry_reuse == TRUE) {
                VM_MAP_HIGHEST_ENTRY(dst_map, entry, start);
                last = entry;
        } else {
                if (dst_map->holelistenabled) {
                        hole_entry = CAST_TO_VM_MAP_ENTRY(dst_map->holes_list);

                        if (hole_entry == NULL) {
                                /*
                                 * No more space in the map?
                                 */
                                vm_map_unlock(dst_map);
                                return KERN_NO_SPACE;
                        }

                        last = hole_entry;
                        start = last->vme_start;
                } else {
                        assert(first_free_is_valid(dst_map));
                        start = ((last = dst_map->first_free) == vm_map_to_entry(dst_map)) ?
                            vm_map_min(dst_map) : last->vme_end;
                }
                start = vm_map_round_page(start,
                    VM_MAP_PAGE_MASK(dst_map));
        }

        while (TRUE) {
                vm_map_entry_t  next = last->vme_next;
                vm_map_offset_t end = start + size;

                if ((end > dst_map->max_offset) || (end < start)) {
                        if (dst_map->wait_for_space) {
                                if (size <= (dst_map->max_offset - dst_map->min_offset)) {
                                        assert_wait((event_t) dst_map,
                                            THREAD_INTERRUPTIBLE);
                                        vm_map_unlock(dst_map);
                                        thread_block(THREAD_CONTINUE_NULL);
                                        goto StartAgain;
                                }
                        }
                        vm_map_unlock(dst_map);
                        return KERN_NO_SPACE;
                }

                if (dst_map->holelistenabled) {
                        if (last->vme_end >= end) {
                                break;
                        }
                } else {
                        /*
                         *      If there are no more entries, we must win.
                         *
                         *      OR
                         *
                         *      If there is another entry, it must be
                         *      after the end of the potential new region.
                         */

                        if (next == vm_map_to_entry(dst_map)) {
                                break;
                        }

                        if (next->vme_start >= end) {
                                break;
                        }
                }

                last = next;

                if (dst_map->holelistenabled) {
                        if (last == CAST_TO_VM_MAP_ENTRY(dst_map->holes_list)) {
                                /*
                                 * Wrapped around
                                 */
                                vm_map_unlock(dst_map);
                                return KERN_NO_SPACE;
                        }
                        start = last->vme_start;
                } else {
                        start = last->vme_end;
                }
                start = vm_map_round_page(start,
                    VM_MAP_PAGE_MASK(dst_map));
        }

        if (dst_map->holelistenabled) {
                if (vm_map_lookup_entry(dst_map, last->vme_start, &last)) {
                        panic("Found an existing entry (%p) instead of potential hole at address: 0x%llx.\n", last, (unsigned long long)last->vme_start);
                }
        }


        adjustment = start - vm_copy_start;
        if (!consume_on_success) {
                /*
                 * We're not allowed to consume "copy", so we'll have to
                 * copy its map entries into the destination map below.
                 * No need to re-allocate map entries from the correct
                 * (pageable or not) zone, since we'll get new map entries
                 * during the transfer.
                 * We'll also adjust the map entries's "start" and "end"
                 * during the transfer, to keep "copy"'s entries consistent
                 * with its "offset".
                 */
                goto after_adjustments;
        }

        /*
         *      Since we're going to just drop the map
         *      entries from the copy into the destination
         *      map, they must come from the same pool.
         */

        if (copy->cpy_hdr.entries_pageable != dst_map->hdr.entries_pageable) {
                /*
                 * Mismatches occur when dealing with the default
                 * pager.
                 */
                zone_t          old_zone;
                vm_map_entry_t  next, new;

                /*
                 * Find the zone that the copies were allocated from
                 */

                entry = vm_map_copy_first_entry(copy);

                /*
                 * Reinitialize the copy so that vm_map_copy_entry_link
                 * will work.
                 */
                vm_map_store_copy_reset(copy, entry);
                copy->cpy_hdr.entries_pageable = dst_map->hdr.entries_pageable;

                /*
                 * Copy each entry.
                 */
                while (entry != vm_map_copy_to_entry(copy)) {
                        new = vm_map_copy_entry_create(copy, !copy->cpy_hdr.entries_pageable);
                        vm_map_entry_copy_full(new, entry);
                        new->vme_no_copy_on_read = FALSE;
                        assert(!new->iokit_acct);
                        if (new->is_sub_map) {
                                /* clr address space specifics */
                                new->use_pmap = FALSE;
                        }
                        vm_map_copy_entry_link(copy,
                            vm_map_copy_last_entry(copy),
                            new);
                        next = entry->vme_next;
                        old_zone = entry->from_reserved_zone ? vm_map_entry_reserved_zone : vm_map_entry_zone;
                        zfree(old_zone, entry);
                        entry = next;
                }
        }

        /*
         *      Adjust the addresses in the copy chain, and
         *      reset the region attributes.
         */

        for (entry = vm_map_copy_first_entry(copy);
            entry != vm_map_copy_to_entry(copy);
            entry = entry->vme_next) {
                if (VM_MAP_PAGE_SHIFT(dst_map) == PAGE_SHIFT) {
                        /*
                         * We're injecting this copy entry into a map that
                         * has the standard page alignment, so clear
                         * "map_aligned" (which might have been inherited
                         * from the original map entry).
                         */
                        entry->map_aligned = FALSE;
                }

                entry->vme_start += adjustment;
                entry->vme_end += adjustment;

                if (entry->map_aligned) {
                        assert(VM_MAP_PAGE_ALIGNED(entry->vme_start,
                            VM_MAP_PAGE_MASK(dst_map)));
                        assert(VM_MAP_PAGE_ALIGNED(entry->vme_end,
                            VM_MAP_PAGE_MASK(dst_map)));
                }

                entry->inheritance = VM_INHERIT_DEFAULT;
                entry->protection = VM_PROT_DEFAULT;
                entry->max_protection = VM_PROT_ALL;
                entry->behavior = VM_BEHAVIOR_DEFAULT;

                /*
                 * If the entry is now wired,
                 * map the pages into the destination map.
                 */
                if (entry->wired_count != 0) {
                        vm_map_offset_t va;
                        vm_object_offset_t       offset;
                        vm_object_t object;
                        vm_prot_t prot;
                        int     type_of_fault;

                        /* TODO4K would need to use actual page size */
                        assert(VM_MAP_PAGE_SHIFT(dst_map) == PAGE_SHIFT);

                        object = VME_OBJECT(entry);
                        offset = VME_OFFSET(entry);
                        va = entry->vme_start;

                        pmap_pageable(dst_map->pmap,
                            entry->vme_start,
                            entry->vme_end,
                            TRUE);

                        while (va < entry->vme_end) {
                                vm_page_t       m;
                                struct vm_object_fault_info fault_info = {};

                                /*
                                 * Look up the page in the object.
                                 * Assert that the page will be found in the
                                 * top object:
                                 * either
                                 *      the object was newly created by
                                 *      vm_object_copy_slowly, and has
                                 *      copies of all of the pages from
                                 *      the source object
                                 * or
                                 *      the object was moved from the old
                                 *      map entry; because the old map
                                 *      entry was wired, all of the pages
                                 *      were in the top-level object.
                                 *      (XXX not true if we wire pages for
                                 *       reading)
                                 */
                                vm_object_lock(object);

                                m = vm_page_lookup(object, offset);
                                if (m == VM_PAGE_NULL || !VM_PAGE_WIRED(m) ||
                                    m->vmp_absent) {
                                        panic("vm_map_copyout: wiring %p", m);
                                }

                                prot = entry->protection;

                                if (override_nx(dst_map, VME_ALIAS(entry)) &&
                                    prot) {
                                        prot |= VM_PROT_EXECUTE;
                                }

                                type_of_fault = DBG_CACHE_HIT_FAULT;

                                fault_info.user_tag = VME_ALIAS(entry);
                                fault_info.pmap_options = 0;
                                if (entry->iokit_acct ||
                                    (!entry->is_sub_map && !entry->use_pmap)) {
                                        fault_info.pmap_options |= PMAP_OPTIONS_ALT_ACCT;
                                }

                                vm_fault_enter(m,
                                    dst_map->pmap,
                                    va,
                                    PAGE_SIZE, 0,
                                    prot,
                                    prot,
                                    VM_PAGE_WIRED(m),
                                    FALSE,            /* change_wiring */
                                    VM_KERN_MEMORY_NONE,            /* tag - not wiring */
                                    &fault_info,
                                    NULL,             /* need_retry */
                                    &type_of_fault);

                                vm_object_unlock(object);

                                offset += PAGE_SIZE_64;
                                va += PAGE_SIZE;
                        }
                }
        }

after_adjustments:

        /*
         *      Correct the page alignment for the result
         */

        *dst_addr = start + (copy->offset - vm_copy_start);

#if KASAN
        kasan_notify_address(*dst_addr, size);
#endif

        /*
         *      Update the hints and the map size
         */

        if (consume_on_success) {
                SAVE_HINT_MAP_WRITE(dst_map, vm_map_copy_last_entry(copy));
        } else {
                SAVE_HINT_MAP_WRITE(dst_map, last);
        }

        dst_map->size += size;

        /*
         *      Link in the copy
         */

        if (consume_on_success) {
                vm_map_copy_insert(dst_map, last, copy);
                if (copy != original_copy) {
                        vm_map_copy_discard(original_copy);
                        original_copy = VM_MAP_COPY_NULL;
                }
        } else {
                vm_map_copy_remap(dst_map, last, copy, adjustment,
                    cur_protection, max_protection,
                    inheritance);
                if (copy != original_copy && original_copy != VM_MAP_COPY_NULL) {
                        vm_map_copy_discard(copy);
                        copy = original_copy;
                }
        }


        vm_map_unlock(dst_map);

        /*
         * XXX  If wiring_required, call vm_map_pageable
         */

        return KERN_SUCCESS;
}

/*
 *      Routine:        vm_map_copyin
 *
 *      Description:
 *              see vm_map_copyin_common.  Exported via Unsupported.exports.
 *
 */

#undef vm_map_copyin

kern_return_t
vm_map_copyin(
        vm_map_t                        src_map,
        vm_map_address_t        src_addr,
        vm_map_size_t           len,
        boolean_t                       src_destroy,
        vm_map_copy_t           *copy_result)   /* OUT */
{
        return vm_map_copyin_common(src_map, src_addr, len, src_destroy,
                   FALSE, copy_result, FALSE);
}

/*
 *      Routine:        vm_map_copyin_common
 *
 *      Description:
 *              Copy the specified region (src_addr, len) from the
 *              source address space (src_map), possibly removing
 *              the region from the source address space (src_destroy).
 *
 *      Returns:
 *              A vm_map_copy_t object (copy_result), suitable for
 *              insertion into another address space (using vm_map_copyout),
 *              copying over another address space region (using
 *              vm_map_copy_overwrite).  If the copy is unused, it
 *              should be destroyed (using vm_map_copy_discard).
 *
 *      In/out conditions:
 *              The source map should not be locked on entry.
 */

typedef struct submap_map {
        vm_map_t        parent_map;
        vm_map_offset_t base_start;
        vm_map_offset_t base_end;
        vm_map_size_t   base_len;
        struct submap_map *next;
} submap_map_t;

kern_return_t
vm_map_copyin_common(
        vm_map_t        src_map,
        vm_map_address_t src_addr,
        vm_map_size_t   len,
        boolean_t       src_destroy,
        __unused boolean_t      src_volatile,
        vm_map_copy_t   *copy_result,   /* OUT */
        boolean_t       use_maxprot)
{
        int flags;

        flags = 0;
        if (src_destroy) {
                flags |= VM_MAP_COPYIN_SRC_DESTROY;
        }
        if (use_maxprot) {
                flags |= VM_MAP_COPYIN_USE_MAXPROT;
        }
        return vm_map_copyin_internal(src_map,
                   src_addr,
                   len,
                   flags,
                   copy_result);
}
kern_return_t
vm_map_copyin_internal(
        vm_map_t        src_map,
        vm_map_address_t src_addr,
        vm_map_size_t   len,
        int             flags,
        vm_map_copy_t   *copy_result)   /* OUT */
{
        vm_map_entry_t  tmp_entry;      /* Result of last map lookup --
                                         * in multi-level lookup, this
                                         * entry contains the actual
                                         * vm_object/offset.
                                         */
        vm_map_entry_t  new_entry = VM_MAP_ENTRY_NULL;  /* Map entry for copy */

        vm_map_offset_t src_start;      /* Start of current entry --
                                         * where copy is taking place now
                                         */
        vm_map_offset_t src_end;        /* End of entire region to be
                                         * copied */
        vm_map_offset_t src_base;
        vm_map_t        base_map = src_map;
        boolean_t       map_share = FALSE;
        submap_map_t    *parent_maps = NULL;

        vm_map_copy_t   copy;           /* Resulting copy */
        vm_map_address_t copy_addr;
        vm_map_size_t   copy_size;
        boolean_t       src_destroy;
        boolean_t       use_maxprot;
        boolean_t       preserve_purgeable;
        boolean_t       entry_was_shared;
        vm_map_entry_t  saved_src_entry;

        if (flags & ~VM_MAP_COPYIN_ALL_FLAGS) {
                return KERN_INVALID_ARGUMENT;
        }

        src_destroy = (flags & VM_MAP_COPYIN_SRC_DESTROY) ? TRUE : FALSE;
        use_maxprot = (flags & VM_MAP_COPYIN_USE_MAXPROT) ? TRUE : FALSE;
        preserve_purgeable =
            (flags & VM_MAP_COPYIN_PRESERVE_PURGEABLE) ? TRUE : FALSE;

        /*
         *      Check for copies of zero bytes.
         */

        if (len == 0) {
                *copy_result = VM_MAP_COPY_NULL;
                return KERN_SUCCESS;
        }

        /*
         *      Check that the end address doesn't overflow
         */
        src_end = src_addr + len;
        if (src_end < src_addr) {
                return KERN_INVALID_ADDRESS;
        }

        /*
         *      Compute (page aligned) start and end of region
         */
        src_start = vm_map_trunc_page(src_addr,
            VM_MAP_PAGE_MASK(src_map));
        src_end = vm_map_round_page(src_end,
            VM_MAP_PAGE_MASK(src_map));

        /*
         * If the copy is sufficiently small, use a kernel buffer instead
         * of making a virtual copy.  The theory being that the cost of
         * setting up VM (and taking C-O-W faults) dominates the copy costs
         * for small regions.
         */
        if ((len < msg_ool_size_small) &&
            !use_maxprot &&
            !preserve_purgeable &&
            !(flags & VM_MAP_COPYIN_ENTRY_LIST) &&
            /*
             * Since the "msg_ool_size_small" threshold was increased and
             * vm_map_copyin_kernel_buffer() doesn't handle accesses beyond the
             * address space limits, we revert to doing a virtual copy if the
             * copied range goes beyond those limits.  Otherwise, mach_vm_read()
             * of the commpage would now fail when it used to work.
             */
            (src_start >= vm_map_min(src_map) &&
            src_start < vm_map_max(src_map) &&
            src_end >= vm_map_min(src_map) &&
            src_end < vm_map_max(src_map))) {
                return vm_map_copyin_kernel_buffer(src_map, src_addr, len,
                           src_destroy, copy_result);
        }

        /*
         *      Allocate a header element for the list.
         *
         *      Use the start and end in the header to
         *      remember the endpoints prior to rounding.
         */

        copy = vm_map_copy_allocate();
        copy->type = VM_MAP_COPY_ENTRY_LIST;
        copy->cpy_hdr.entries_pageable = TRUE;
        copy->cpy_hdr.page_shift = VM_MAP_PAGE_SHIFT(src_map);

        vm_map_store_init( &(copy->cpy_hdr));

        copy->offset = src_addr;
        copy->size = len;

        new_entry = vm_map_copy_entry_create(copy, !copy->cpy_hdr.entries_pageable);

#define RETURN(x)                                               \
        MACRO_BEGIN                                             \
        vm_map_unlock(src_map);                                 \
        if(src_map != base_map)                                 \
                vm_map_deallocate(src_map);                     \
        if (new_entry != VM_MAP_ENTRY_NULL)                     \
                vm_map_copy_entry_dispose(copy,new_entry);      \
        vm_map_copy_discard(copy);                              \
        {                                                       \
                submap_map_t    *_ptr;                          \
                                                                \
                for(_ptr = parent_maps; _ptr != NULL; _ptr = parent_maps) { \
                        parent_maps=parent_maps->next;          \
                        if (_ptr->parent_map != base_map)       \
                                vm_map_deallocate(_ptr->parent_map);    \
                        kfree(_ptr, sizeof(submap_map_t));      \
                }                                               \
        }                                                       \
        MACRO_RETURN(x);                                        \
        MACRO_END

        /*
         *      Find the beginning of the region.
         */

        vm_map_lock(src_map);

        /*
         * Lookup the original "src_addr" rather than the truncated
         * "src_start", in case "src_start" falls in a non-map-aligned
         * map entry *before* the map entry that contains "src_addr"...
         */
        if (!vm_map_lookup_entry(src_map, src_addr, &tmp_entry)) {
                RETURN(KERN_INVALID_ADDRESS);
        }
        if (!tmp_entry->is_sub_map) {
                /*
                 * ... but clip to the map-rounded "src_start" rather than
                 * "src_addr" to preserve map-alignment.  We'll adjust the
                 * first copy entry at the end, if needed.
                 */
                vm_map_clip_start(src_map, tmp_entry, src_start);
        }
        if (src_start < tmp_entry->vme_start) {
                /*
                 * Move "src_start" up to the start of the
                 * first map entry to copy.
                 */
                src_start = tmp_entry->vme_start;
        }
        /* set for later submap fix-up */
        copy_addr = src_start;

        /*
         *      Go through entries until we get to the end.
         */

        while (TRUE) {
                vm_map_entry_t  src_entry = tmp_entry;  /* Top-level entry */
                vm_map_size_t   src_size;               /* Size of source
                                                         * map entry (in both
                                                         * maps)
                                                         */

                vm_object_t             src_object;     /* Object to copy */
                vm_object_offset_t      src_offset;

                boolean_t       src_needs_copy;         /* Should source map
                                                         * be made read-only
                                                         * for copy-on-write?
                                                         */

                boolean_t       new_entry_needs_copy;   /* Will new entry be COW? */

                boolean_t       was_wired;              /* Was source wired? */
                vm_map_version_t version;               /* Version before locks
                                                         * dropped to make copy
                                                         */
                kern_return_t   result;                 /* Return value from
                                                         * copy_strategically.
                                                         */
                while (tmp_entry->is_sub_map) {
                        vm_map_size_t submap_len;
                        submap_map_t *ptr;

                        ptr = (submap_map_t *)kalloc(sizeof(submap_map_t));
                        ptr->next = parent_maps;
                        parent_maps = ptr;
                        ptr->parent_map = src_map;
                        ptr->base_start = src_start;
                        ptr->base_end = src_end;
                        submap_len = tmp_entry->vme_end - src_start;
                        if (submap_len > (src_end - src_start)) {
                                submap_len = src_end - src_start;
                        }
                        ptr->base_len = submap_len;

                        src_start -= tmp_entry->vme_start;
                        src_start += VME_OFFSET(tmp_entry);
                        src_end = src_start + submap_len;
                        src_map = VME_SUBMAP(tmp_entry);
                        vm_map_lock(src_map);
                        /* keep an outstanding reference for all maps in */
                        /* the parents tree except the base map */
                        vm_map_reference(src_map);
                        vm_map_unlock(ptr->parent_map);
                        if (!vm_map_lookup_entry(
                                    src_map, src_start, &tmp_entry)) {
                                RETURN(KERN_INVALID_ADDRESS);
                        }
                        map_share = TRUE;
                        if (!tmp_entry->is_sub_map) {
                                vm_map_clip_start(src_map, tmp_entry, src_start);
                        }
                        src_entry = tmp_entry;
                }
                /* we are now in the lowest level submap... */

                if ((VME_OBJECT(tmp_entry) != VM_OBJECT_NULL) &&
                    (VME_OBJECT(tmp_entry)->phys_contiguous)) {
                        /* This is not, supported for now.In future */
                        /* we will need to detect the phys_contig   */
                        /* condition and then upgrade copy_slowly   */
                        /* to do physical copy from the device mem  */
                        /* based object. We can piggy-back off of   */
                        /* the was wired boolean to set-up the      */
                        /* proper handling */
                        RETURN(KERN_PROTECTION_FAILURE);
                }
                /*
                 *      Create a new address map entry to hold the result.
                 *      Fill in the fields from the appropriate source entries.
                 *      We must unlock the source map to do this if we need
                 *      to allocate a map entry.
                 */
                if (new_entry == VM_MAP_ENTRY_NULL) {
                        version.main_timestamp = src_map->timestamp;
                        vm_map_unlock(src_map);

                        new_entry = vm_map_copy_entry_create(copy, !copy->cpy_hdr.entries_pageable);

                        vm_map_lock(src_map);
                        if ((version.main_timestamp + 1) != src_map->timestamp) {
                                if (!vm_map_lookup_entry(src_map, src_start,
                                    &tmp_entry)) {
                                        RETURN(KERN_INVALID_ADDRESS);
                                }
                                if (!tmp_entry->is_sub_map) {
                                        vm_map_clip_start(src_map, tmp_entry, src_start);
                                }
                                continue; /* restart w/ new tmp_entry */
                        }
                }

                /*
                 *      Verify that the region can be read.
                 */
                if (((src_entry->protection & VM_PROT_READ) == VM_PROT_NONE &&
                    !use_maxprot) ||
                    (src_entry->max_protection & VM_PROT_READ) == 0) {
                        RETURN(KERN_PROTECTION_FAILURE);
                }

                /*
                 *      Clip against the endpoints of the entire region.
                 */

                vm_map_clip_end(src_map, src_entry, src_end);

                src_size = src_entry->vme_end - src_start;
                src_object = VME_OBJECT(src_entry);
                src_offset = VME_OFFSET(src_entry);
                was_wired = (src_entry->wired_count != 0);

                vm_map_entry_copy(src_map, new_entry, src_entry);
                if (new_entry->is_sub_map) {
                        /* clr address space specifics */
                        new_entry->use_pmap = FALSE;
                } else {
                        /*
                         * We're dealing with a copy-on-write operation,
                         * so the resulting mapping should not inherit the
                         * original mapping's accounting settings.
                         * "iokit_acct" should have been cleared in
                         * vm_map_entry_copy().
                         * "use_pmap" should be reset to its default (TRUE)
                         * so that the new mapping gets accounted for in
                         * the task's memory footprint.
                         */
                        assert(!new_entry->iokit_acct);
                        new_entry->use_pmap = TRUE;
                }

                /*
                 *      Attempt non-blocking copy-on-write optimizations.
                 */

                /*
                 * If we are destroying the source, and the object
                 * is internal, we could move the object reference
                 * from the source to the copy.  The copy is
                 * copy-on-write only if the source is.
                 * We make another reference to the object, because
                 * destroying the source entry will deallocate it.
                 *
                 * This memory transfer has to be atomic, (to prevent
                 * the VM object from being shared or copied while
                 * it's being moved here), so we could only do this
                 * if we won't have to unlock the VM map until the
                 * original mapping has been fully removed.
                 */

RestartCopy:
                if ((src_object == VM_OBJECT_NULL ||
                    (!was_wired && !map_share && !tmp_entry->is_shared
                    && !(debug4k_no_cow_copyin && VM_MAP_PAGE_SHIFT(src_map) < PAGE_SHIFT))) &&
                    vm_object_copy_quickly(
                            VME_OBJECT_PTR(new_entry),
                            src_offset,
                            src_size,
                            &src_needs_copy,
                            &new_entry_needs_copy)) {
                        new_entry->needs_copy = new_entry_needs_copy;

                        /*
                         *      Handle copy-on-write obligations
                         */

                        if (src_needs_copy && !tmp_entry->needs_copy) {
                                vm_prot_t prot;

                                prot = src_entry->protection & ~VM_PROT_WRITE;

                                if (override_nx(src_map, VME_ALIAS(src_entry))
                                    && prot) {
                                        prot |= VM_PROT_EXECUTE;
                                }

                                vm_object_pmap_protect(
                                        src_object,
                                        src_offset,
                                        src_size,
                                        (src_entry->is_shared ?
                                        PMAP_NULL
                                        : src_map->pmap),
                                        VM_MAP_PAGE_SIZE(src_map),
                                        src_entry->vme_start,
                                        prot);

                                assert(tmp_entry->wired_count == 0);
                                tmp_entry->needs_copy = TRUE;
                        }

                        /*
                         *      The map has never been unlocked, so it's safe
                         *      to move to the next entry rather than doing
                         *      another lookup.
                         */

                        goto CopySuccessful;
                }

                entry_was_shared = tmp_entry->is_shared;

                /*
                 *      Take an object reference, so that we may
                 *      release the map lock(s).
                 */

                assert(src_object != VM_OBJECT_NULL);
                vm_object_reference(src_object);

                /*
                 *      Record the timestamp for later verification.
                 *      Unlock the map.
                 */

                version.main_timestamp = src_map->timestamp;
                vm_map_unlock(src_map); /* Increments timestamp once! */
                saved_src_entry = src_entry;
                tmp_entry = VM_MAP_ENTRY_NULL;
                src_entry = VM_MAP_ENTRY_NULL;

                /*
                 *      Perform the copy
                 */

                if (was_wired ||
                    (debug4k_no_cow_copyin &&
                    VM_MAP_PAGE_SHIFT(src_map) < PAGE_SHIFT)) {
CopySlowly:
                        vm_object_lock(src_object);
                        result = vm_object_copy_slowly(
                                src_object,
                                src_offset,
                                src_size,
                                THREAD_UNINT,
                                VME_OBJECT_PTR(new_entry));
                        VME_OFFSET_SET(new_entry,
                            src_offset - vm_object_trunc_page(src_offset));
                        new_entry->needs_copy = FALSE;
                } else if (src_object->copy_strategy == MEMORY_OBJECT_COPY_SYMMETRIC &&
                    (entry_was_shared || map_share)) {
                        vm_object_t new_object;

                        vm_object_lock_shared(src_object);
                        new_object = vm_object_copy_delayed(
                                src_object,
                                src_offset,
                                src_size,
                                TRUE);
                        if (new_object == VM_OBJECT_NULL) {
                                goto CopySlowly;
                        }

                        VME_OBJECT_SET(new_entry, new_object);
                        assert(new_entry->wired_count == 0);
                        new_entry->needs_copy = TRUE;
                        assert(!new_entry->iokit_acct);
                        assert(new_object->purgable == VM_PURGABLE_DENY);
                        assertf(new_entry->use_pmap, "src_map %p new_entry %p\n", src_map, new_entry);
                        result = KERN_SUCCESS;
                } else {
                        vm_object_offset_t new_offset;
                        new_offset = VME_OFFSET(new_entry);
                        result = vm_object_copy_strategically(src_object,
                            src_offset,
                            src_size,
                            VME_OBJECT_PTR(new_entry),
                            &new_offset,
                            &new_entry_needs_copy);
                        if (new_offset != VME_OFFSET(new_entry)) {
                                VME_OFFSET_SET(new_entry, new_offset);
                        }

                        new_entry->needs_copy = new_entry_needs_copy;
                }

                if (result == KERN_SUCCESS &&
                    ((preserve_purgeable &&
                    src_object->purgable != VM_PURGABLE_DENY) ||
                    new_entry->used_for_jit)) {
                        /*
                         * Purgeable objects should be COPY_NONE, true share;
                         * this should be propogated to the copy.
                         *
                         * Also force mappings the pmap specially protects to
                         * be COPY_NONE; trying to COW these mappings would
                         * change the effective protections, which could have
                         * side effects if the pmap layer relies on the
                         * specified protections.
                         */

                        vm_object_t     new_object;

                        new_object = VME_OBJECT(new_entry);
                        assert(new_object != src_object);
                        vm_object_lock(new_object);
                        assert(new_object->ref_count == 1);
                        assert(new_object->shadow == VM_OBJECT_NULL);
                        assert(new_object->copy == VM_OBJECT_NULL);
                        assert(new_object->vo_owner == NULL);

                        new_object->copy_strategy = MEMORY_OBJECT_COPY_NONE;

                        if (preserve_purgeable &&
                            src_object->purgable != VM_PURGABLE_DENY) {
                                new_object->true_share = TRUE;

                                /* start as non-volatile with no owner... */
                                new_object->purgable = VM_PURGABLE_NONVOLATILE;
                                vm_purgeable_nonvolatile_enqueue(new_object, NULL);
                                /* ... and move to src_object's purgeable state */
                                if (src_object->purgable != VM_PURGABLE_NONVOLATILE) {
                                        int state;
                                        state = src_object->purgable;
                                        vm_object_purgable_control(
                                                new_object,
                                                VM_PURGABLE_SET_STATE_FROM_KERNEL,
                                                &state);
                                }
                                /* no pmap accounting for purgeable objects */
                                new_entry->use_pmap = FALSE;
                        }

                        vm_object_unlock(new_object);
                        new_object = VM_OBJECT_NULL;
                }

                if (result != KERN_SUCCESS &&
                    result != KERN_MEMORY_RESTART_COPY) {
                        vm_map_lock(src_map);
                        RETURN(result);
                }

                /*
                 *      Throw away the extra reference
                 */

                vm_object_deallocate(src_object);

                /*
                 *      Verify that the map has not substantially
                 *      changed while the copy was being made.
                 */

                vm_map_lock(src_map);

                if ((version.main_timestamp + 1) == src_map->timestamp) {
                        /* src_map hasn't changed: src_entry is still valid */
                        src_entry = saved_src_entry;
                        goto VerificationSuccessful;
                }

                /*
                 *      Simple version comparison failed.
                 *
                 *      Retry the lookup and verify that the
                 *      same object/offset are still present.
                 *
                 *      [Note: a memory manager that colludes with
                 *      the calling task can detect that we have
                 *      cheated.  While the map was unlocked, the
                 *      mapping could have been changed and restored.]
                 */

                if (!vm_map_lookup_entry(src_map, src_start, &tmp_entry)) {
                        if (result != KERN_MEMORY_RESTART_COPY) {
                                vm_object_deallocate(VME_OBJECT(new_entry));
                                VME_OBJECT_SET(new_entry, VM_OBJECT_NULL);
                                /* reset accounting state */
                                new_entry->iokit_acct = FALSE;
                                new_entry->use_pmap = TRUE;
                        }
                        RETURN(KERN_INVALID_ADDRESS);
                }

                src_entry = tmp_entry;
                vm_map_clip_start(src_map, src_entry, src_start);

                if ((((src_entry->protection & VM_PROT_READ) == VM_PROT_NONE) &&
                    !use_maxprot) ||
                    ((src_entry->max_protection & VM_PROT_READ) == 0)) {
                        goto VerificationFailed;
                }

                if (src_entry->vme_end < new_entry->vme_end) {
                        /*
                         * This entry might have been shortened
                         * (vm_map_clip_end) or been replaced with
                         * an entry that ends closer to "src_start"
                         * than before.
                         * Adjust "new_entry" accordingly; copying
                         * less memory would be correct but we also
                         * redo the copy (see below) if the new entry
                         * no longer points at the same object/offset.
                         */
                        assert(VM_MAP_PAGE_ALIGNED(src_entry->vme_end,
                            VM_MAP_COPY_PAGE_MASK(copy)));
                        new_entry->vme_end = src_entry->vme_end;
                        src_size = new_entry->vme_end - src_start;
                } else if (src_entry->vme_end > new_entry->vme_end) {
                        /*
                         * This entry might have been extended
                         * (vm_map_entry_simplify() or coalesce)
                         * or been replaced with an entry that ends farther
                         * from "src_start" than before.
                         *
                         * We've called vm_object_copy_*() only on
                         * the previous <start:end> range, so we can't
                         * just extend new_entry.  We have to re-do
                         * the copy based on the new entry as if it was
                         * pointing at a different object/offset (see
                         * "Verification failed" below).
                         */
                }

                if ((VME_OBJECT(src_entry) != src_object) ||
                    (VME_OFFSET(src_entry) != src_offset) ||
                    (src_entry->vme_end > new_entry->vme_end)) {
                        /*
                         *      Verification failed.
                         *
                         *      Start over with this top-level entry.
                         */

VerificationFailed:     ;

                        vm_object_deallocate(VME_OBJECT(new_entry));
                        tmp_entry = src_entry;
                        continue;
                }

                /*
                 *      Verification succeeded.
                 */

VerificationSuccessful:;

                if (result == KERN_MEMORY_RESTART_COPY) {
                        goto RestartCopy;
                }

                /*
                 *      Copy succeeded.
                 */

CopySuccessful: ;

                /*
                 *      Link in the new copy entry.
                 */

                vm_map_copy_entry_link(copy, vm_map_copy_last_entry(copy),
                    new_entry);

                /*
                 *      Determine whether the entire region
                 *      has been copied.
                 */
                src_base = src_start;
                src_start = new_entry->vme_end;
                new_entry = VM_MAP_ENTRY_NULL;
                while ((src_start >= src_end) && (src_end != 0)) {
                        submap_map_t    *ptr;

                        if (src_map == base_map) {
                                /* back to the top */
                                break;
                        }

                        ptr = parent_maps;
                        assert(ptr != NULL);
                        parent_maps = parent_maps->next;

                        /* fix up the damage we did in that submap */
                        vm_map_simplify_range(src_map,
                            src_base,
                            src_end);

                        vm_map_unlock(src_map);
                        vm_map_deallocate(src_map);
                        vm_map_lock(ptr->parent_map);
                        src_map = ptr->parent_map;
                        src_base = ptr->base_start;
                        src_start = ptr->base_start + ptr->base_len;
                        src_end = ptr->base_end;
                        if (!vm_map_lookup_entry(src_map,
                            src_start,
                            &tmp_entry) &&
                            (src_end > src_start)) {
                                RETURN(KERN_INVALID_ADDRESS);
                        }
                        kfree(ptr, sizeof(submap_map_t));
                        if (parent_maps == NULL) {
                                map_share = FALSE;
                        }
                        src_entry = tmp_entry->vme_prev;
                }

                if ((VM_MAP_PAGE_SHIFT(src_map) != PAGE_SHIFT) &&
                    (src_start >= src_addr + len) &&
                    (src_addr + len != 0)) {
                        /*
                         * Stop copying now, even though we haven't reached
                         * "src_end".  We'll adjust the end of the last copy
                         * entry at the end, if needed.
                         *
                         * If src_map's aligment is different from the
                         * system's page-alignment, there could be
                         * extra non-map-aligned map entries between
                         * the original (non-rounded) "src_addr + len"
                         * and the rounded "src_end".
                         * We do not want to copy those map entries since
                         * they're not part of the copied range.
                         */
                        break;
                }

                if ((src_start >= src_end) && (src_end != 0)) {
                        break;
                }

                /*
                 *      Verify that there are no gaps in the region
                 */

                tmp_entry = src_entry->vme_next;
                if ((tmp_entry->vme_start != src_start) ||
                    (tmp_entry == vm_map_to_entry(src_map))) {
                        RETURN(KERN_INVALID_ADDRESS);
                }
        }

        /*
         * If the source should be destroyed, do it now, since the
         * copy was successful.
         */
        if (src_destroy) {
                (void) vm_map_delete(
                        src_map,
                        vm_map_trunc_page(src_addr,
                        VM_MAP_PAGE_MASK(src_map)),
                        src_end,
                        ((src_map == kernel_map) ?
                        VM_MAP_REMOVE_KUNWIRE :
                        VM_MAP_REMOVE_NO_FLAGS),
                        VM_MAP_NULL);
        } else {
                /* fix up the damage we did in the base map */
                vm_map_simplify_range(
                        src_map,
                        vm_map_trunc_page(src_addr,
                        VM_MAP_PAGE_MASK(src_map)),
                        vm_map_round_page(src_end,
                        VM_MAP_PAGE_MASK(src_map)));
        }

        vm_map_unlock(src_map);
        tmp_entry = VM_MAP_ENTRY_NULL;

        if (VM_MAP_PAGE_SHIFT(src_map) > PAGE_SHIFT &&
            VM_MAP_PAGE_SHIFT(src_map) != VM_MAP_COPY_PAGE_SHIFT(copy)) {
                vm_map_offset_t original_start, original_offset, original_end;

                assert(VM_MAP_COPY_PAGE_MASK(copy) == PAGE_MASK);

                /* adjust alignment of first copy_entry's "vme_start" */
                tmp_entry = vm_map_copy_first_entry(copy);
                if (tmp_entry != vm_map_copy_to_entry(copy)) {
                        vm_map_offset_t adjustment;

                        original_start = tmp_entry->vme_start;
                        original_offset = VME_OFFSET(tmp_entry);

                        /* map-align the start of the first copy entry... */
                        adjustment = (tmp_entry->vme_start -
                            vm_map_trunc_page(
                                    tmp_entry->vme_start,
                                    VM_MAP_PAGE_MASK(src_map)));
                        tmp_entry->vme_start -= adjustment;
                        VME_OFFSET_SET(tmp_entry,
                            VME_OFFSET(tmp_entry) - adjustment);
                        copy_addr -= adjustment;
                        assert(tmp_entry->vme_start < tmp_entry->vme_end);
                        /* ... adjust for mis-aligned start of copy range */
                        adjustment =
                            (vm_map_trunc_page(copy->offset,
                            PAGE_MASK) -
                            vm_map_trunc_page(copy->offset,
                            VM_MAP_PAGE_MASK(src_map)));
                        if (adjustment) {
                                assert(page_aligned(adjustment));
                                assert(adjustment < VM_MAP_PAGE_SIZE(src_map));
                                tmp_entry->vme_start += adjustment;
                                VME_OFFSET_SET(tmp_entry,
                                    (VME_OFFSET(tmp_entry) +
                                    adjustment));
                                copy_addr += adjustment;
                                assert(tmp_entry->vme_start < tmp_entry->vme_end);
                        }

                        /*
                         * Assert that the adjustments haven't exposed
                         * more than was originally copied...
                         */
                        assert(tmp_entry->vme_start >= original_start);
                        assert(VME_OFFSET(tmp_entry) >= original_offset);
                        /*
                         * ... and that it did not adjust outside of a
                         * a single 16K page.
                         */
                        assert(vm_map_trunc_page(tmp_entry->vme_start,
                            VM_MAP_PAGE_MASK(src_map)) ==
                            vm_map_trunc_page(original_start,
                            VM_MAP_PAGE_MASK(src_map)));
                }

                /* adjust alignment of last copy_entry's "vme_end" */
                tmp_entry = vm_map_copy_last_entry(copy);
                if (tmp_entry != vm_map_copy_to_entry(copy)) {
                        vm_map_offset_t adjustment;

                        original_end = tmp_entry->vme_end;

                        /* map-align the end of the last copy entry... */
                        tmp_entry->vme_end =
                            vm_map_round_page(tmp_entry->vme_end,
                            VM_MAP_PAGE_MASK(src_map));
                        /* ... adjust for mis-aligned end of copy range */
                        adjustment =
                            (vm_map_round_page((copy->offset +
                            copy->size),
                            VM_MAP_PAGE_MASK(src_map)) -
                            vm_map_round_page((copy->offset +
                            copy->size),
                            PAGE_MASK));
                        if (adjustment) {
                                assert(page_aligned(adjustment));
                                assert(adjustment < VM_MAP_PAGE_SIZE(src_map));
                                tmp_entry->vme_end -= adjustment;
                                assert(tmp_entry->vme_start < tmp_entry->vme_end);
                        }

                        /*
                         * Assert that the adjustments haven't exposed
                         * more than was originally copied...
                         */
                        assert(tmp_entry->vme_end <= original_end);
                        /*
                         * ... and that it did not adjust outside of a
                         * a single 16K page.
                         */
                        assert(vm_map_round_page(tmp_entry->vme_end,
                            VM_MAP_PAGE_MASK(src_map)) ==
                            vm_map_round_page(original_end,
                            VM_MAP_PAGE_MASK(src_map)));
                }
        }

        /* Fix-up start and end points in copy.  This is necessary */
        /* when the various entries in the copy object were picked */
        /* up from different sub-maps */

        tmp_entry = vm_map_copy_first_entry(copy);
        copy_size = 0; /* compute actual size */
        while (tmp_entry != vm_map_copy_to_entry(copy)) {
                assert(VM_MAP_PAGE_ALIGNED(
                            copy_addr + (tmp_entry->vme_end -
                            tmp_entry->vme_start),
                            MIN(VM_MAP_COPY_PAGE_MASK(copy), PAGE_MASK)));
                assert(VM_MAP_PAGE_ALIGNED(
                            copy_addr,
                            MIN(VM_MAP_COPY_PAGE_MASK(copy), PAGE_MASK)));

                /*
                 * The copy_entries will be injected directly into the
                 * destination map and might not be "map aligned" there...
                 */
                tmp_entry->map_aligned = FALSE;

                tmp_entry->vme_end = copy_addr +
                    (tmp_entry->vme_end - tmp_entry->vme_start);
                tmp_entry->vme_start = copy_addr;
                assert(tmp_entry->vme_start < tmp_entry->vme_end);
                copy_addr += tmp_entry->vme_end - tmp_entry->vme_start;
                copy_size += tmp_entry->vme_end - tmp_entry->vme_start;
                tmp_entry = (struct vm_map_entry *)tmp_entry->vme_next;
        }

        if (VM_MAP_PAGE_SHIFT(src_map) != PAGE_SHIFT &&
            copy_size < copy->size) {
                /*
                 * The actual size of the VM map copy is smaller than what
                 * was requested by the caller.  This must be because some
                 * PAGE_SIZE-sized pages are missing at the end of the last
                 * VM_MAP_PAGE_SIZE(src_map)-sized chunk of the range.
                 * The caller might not have been aware of those missing
                 * pages and might not want to be aware of it, which is
                 * fine as long as they don't try to access (and crash on)
                 * those missing pages.
                 * Let's adjust the size of the "copy", to avoid failing
                 * in vm_map_copyout() or vm_map_copy_overwrite().
                 */
                assert(vm_map_round_page(copy_size,
                    VM_MAP_PAGE_MASK(src_map)) ==
                    vm_map_round_page(copy->size,
                    VM_MAP_PAGE_MASK(src_map)));
                copy->size = copy_size;
        }

        *copy_result = copy;
        return KERN_SUCCESS;

#undef  RETURN
}

kern_return_t
vm_map_copy_extract(
        vm_map_t                src_map,
        vm_map_address_t        src_addr,
        vm_map_size_t           len,
        vm_prot_t               required_prot,
        boolean_t               do_copy,
        vm_map_copy_t           *copy_result,   /* OUT */
        vm_prot_t               *cur_prot,      /* OUT */
        vm_prot_t               *max_prot,      /* OUT */
        vm_inherit_t            inheritance,
        vm_map_kernel_flags_t   vmk_flags)
{
        vm_map_copy_t   copy;
        kern_return_t   kr;

        /*
         *      Check for copies of zero bytes.
         */

        if (len == 0) {
                *copy_result = VM_MAP_COPY_NULL;
                return KERN_SUCCESS;
        }

        /*
         *      Check that the end address doesn't overflow
         */
        if (src_addr + len < src_addr) {
                return KERN_INVALID_ADDRESS;
        }

        if (VM_MAP_PAGE_SIZE(src_map) < PAGE_SIZE) {
                DEBUG4K_SHARE("src_map %p src_addr 0x%llx src_end 0x%llx\n", src_map, (uint64_t)src_addr, (uint64_t)(src_addr + len));
        }

        /*
         *      Allocate a header element for the list.
         *
         *      Use the start and end in the header to
         *      remember the endpoints prior to rounding.
         */

        copy = vm_map_copy_allocate();
        copy->type = VM_MAP_COPY_ENTRY_LIST;
        copy->cpy_hdr.entries_pageable = vmk_flags.vmkf_copy_pageable;

        vm_map_store_init(&copy->cpy_hdr);

        copy->offset = 0;
        copy->size = len;

        kr = vm_map_remap_extract(src_map,
            src_addr,
            len,
            required_prot,
            do_copy,                       /* copy */
            &copy->cpy_hdr,
            cur_prot,
            max_prot,
            inheritance,
            vmk_flags);
        if (kr != KERN_SUCCESS) {
                vm_map_copy_discard(copy);
                return kr;
        }
        assert((*cur_prot & required_prot) == required_prot);
        assert((*max_prot & required_prot) == required_prot);

        *copy_result = copy;
        return KERN_SUCCESS;
}

/*
 *      vm_map_copyin_object:
 *
 *      Create a copy object from an object.
 *      Our caller donates an object reference.
 */

kern_return_t
vm_map_copyin_object(
        vm_object_t             object,
        vm_object_offset_t      offset, /* offset of region in object */
        vm_object_size_t        size,   /* size of region in object */
        vm_map_copy_t   *copy_result)   /* OUT */
{
        vm_map_copy_t   copy;           /* Resulting copy */

        /*
         *      We drop the object into a special copy object
         *      that contains the object directly.
         */

        copy = vm_map_copy_allocate();
        copy->type = VM_MAP_COPY_OBJECT;
        copy->cpy_object = object;
        copy->offset = offset;
        copy->size = size;

        *copy_result = copy;
        return KERN_SUCCESS;
}

static void
vm_map_fork_share(
        vm_map_t        old_map,
        vm_map_entry_t  old_entry,
        vm_map_t        new_map)
{
        vm_object_t     object;
        vm_map_entry_t  new_entry;

        /*
         *      New sharing code.  New map entry
         *      references original object.  Internal
         *      objects use asynchronous copy algorithm for
         *      future copies.  First make sure we have
         *      the right object.  If we need a shadow,
         *      or someone else already has one, then
         *      make a new shadow and share it.
         */

        object = VME_OBJECT(old_entry);
        if (old_entry->is_sub_map) {
                assert(old_entry->wired_count == 0);
#ifndef NO_NESTED_PMAP
                if (old_entry->use_pmap) {
                        kern_return_t   result;

                        result = pmap_nest(new_map->pmap,
                            (VME_SUBMAP(old_entry))->pmap,
                            (addr64_t)old_entry->vme_start,
                            (uint64_t)(old_entry->vme_end - old_entry->vme_start));
                        if (result) {
                                panic("vm_map_fork_share: pmap_nest failed!");
                        }
                }
#endif  /* NO_NESTED_PMAP */
        } else if (object == VM_OBJECT_NULL) {
                object = vm_object_allocate((vm_map_size_t)(old_entry->vme_end -
                    old_entry->vme_start));
                VME_OFFSET_SET(old_entry, 0);
                VME_OBJECT_SET(old_entry, object);
                old_entry->use_pmap = TRUE;
//              assert(!old_entry->needs_copy);
        } else if (object->copy_strategy !=
            MEMORY_OBJECT_COPY_SYMMETRIC) {
                /*
                 *      We are already using an asymmetric
                 *      copy, and therefore we already have
                 *      the right object.
                 */

                assert(!old_entry->needs_copy);
        } else if (old_entry->needs_copy ||       /* case 1 */
            object->shadowed ||                 /* case 2 */
            (!object->true_share &&             /* case 3 */
            !old_entry->is_shared &&
            (object->vo_size >
            (vm_map_size_t)(old_entry->vme_end -
            old_entry->vme_start)))) {
                /*
                 *      We need to create a shadow.
                 *      There are three cases here.
                 *      In the first case, we need to
                 *      complete a deferred symmetrical
                 *      copy that we participated in.
                 *      In the second and third cases,
                 *      we need to create the shadow so
                 *      that changes that we make to the
                 *      object do not interfere with
                 *      any symmetrical copies which
                 *      have occured (case 2) or which
                 *      might occur (case 3).
                 *
                 *      The first case is when we had
                 *      deferred shadow object creation
                 *      via the entry->needs_copy mechanism.
                 *      This mechanism only works when
                 *      only one entry points to the source
                 *      object, and we are about to create
                 *      a second entry pointing to the
                 *      same object. The problem is that
                 *      there is no way of mapping from
                 *      an object to the entries pointing
                 *      to it. (Deferred shadow creation
                 *      works with one entry because occurs
                 *      at fault time, and we walk from the
                 *      entry to the object when handling
                 *      the fault.)
                 *
                 *      The second case is when the object
                 *      to be shared has already been copied
                 *      with a symmetric copy, but we point
                 *      directly to the object without
                 *      needs_copy set in our entry. (This
                 *      can happen because different ranges
                 *      of an object can be pointed to by
                 *      different entries. In particular,
                 *      a single entry pointing to an object
                 *      can be split by a call to vm_inherit,
                 *      which, combined with task_create, can
                 *      result in the different entries
                 *      having different needs_copy values.)
                 *      The shadowed flag in the object allows
                 *      us to detect this case. The problem
                 *      with this case is that if this object
                 *      has or will have shadows, then we
                 *      must not perform an asymmetric copy
                 *      of this object, since such a copy
                 *      allows the object to be changed, which
                 *      will break the previous symmetrical
                 *      copies (which rely upon the object
                 *      not changing). In a sense, the shadowed
                 *      flag says "don't change this object".
                 *      We fix this by creating a shadow
                 *      object for this object, and sharing
                 *      that. This works because we are free
                 *      to change the shadow object (and thus
                 *      to use an asymmetric copy strategy);
                 *      this is also semantically correct,
                 *      since this object is temporary, and
                 *      therefore a copy of the object is
                 *      as good as the object itself. (This
                 *      is not true for permanent objects,
                 *      since the pager needs to see changes,
                 *      which won't happen if the changes
                 *      are made to a copy.)
                 *
                 *      The third case is when the object
                 *      to be shared has parts sticking
                 *      outside of the entry we're working
                 *      with, and thus may in the future
                 *      be subject to a symmetrical copy.
                 *      (This is a preemptive version of
                 *      case 2.)
                 */
                VME_OBJECT_SHADOW(old_entry,
                    (vm_map_size_t) (old_entry->vme_end -
                    old_entry->vme_start));

                /*
                 *      If we're making a shadow for other than
                 *      copy on write reasons, then we have
                 *      to remove write permission.
                 */

                if (!old_entry->needs_copy &&
                    (old_entry->protection & VM_PROT_WRITE)) {
                        vm_prot_t prot;

                        assert(!pmap_has_prot_policy(old_map->pmap, old_entry->translated_allow_execute, old_entry->protection));

                        prot = old_entry->protection & ~VM_PROT_WRITE;

                        assert(!pmap_has_prot_policy(old_map->pmap, old_entry->translated_allow_execute, prot));

                        if (override_nx(old_map, VME_ALIAS(old_entry)) && prot) {
                                prot |= VM_PROT_EXECUTE;
                        }


                        if (old_map->mapped_in_other_pmaps) {
                                vm_object_pmap_protect(
                                        VME_OBJECT(old_entry),
                                        VME_OFFSET(old_entry),
                                        (old_entry->vme_end -
                                        old_entry->vme_start),
                                        PMAP_NULL,
                                        PAGE_SIZE,
                                        old_entry->vme_start,
                                        prot);
                        } else {
                                pmap_protect(old_map->pmap,
                                    old_entry->vme_start,
                                    old_entry->vme_end,
                                    prot);
                        }
                }

                old_entry->needs_copy = FALSE;
                object = VME_OBJECT(old_entry);
        }


        /*
         *      If object was using a symmetric copy strategy,
         *      change its copy strategy to the default
         *      asymmetric copy strategy, which is copy_delay
         *      in the non-norma case and copy_call in the
         *      norma case. Bump the reference count for the
         *      new entry.
         */

        if (old_entry->is_sub_map) {
                vm_map_lock(VME_SUBMAP(old_entry));
                vm_map_reference(VME_SUBMAP(old_entry));
                vm_map_unlock(VME_SUBMAP(old_entry));
        } else {
                vm_object_lock(object);
                vm_object_reference_locked(object);
                if (object->copy_strategy == MEMORY_OBJECT_COPY_SYMMETRIC) {
                        object->copy_strategy = MEMORY_OBJECT_COPY_DELAY;
                }
                vm_object_unlock(object);
        }

        /*
         *      Clone the entry, using object ref from above.
         *      Mark both entries as shared.
         */

        new_entry = vm_map_entry_create(new_map, FALSE); /* Never the kernel
                                                          * map or descendants */
        vm_map_entry_copy(old_map, new_entry, old_entry);
        old_entry->is_shared = TRUE;
        new_entry->is_shared = TRUE;

        /*
         * We're dealing with a shared mapping, so the resulting mapping
         * should inherit some of the original mapping's accounting settings.
         * "iokit_acct" should have been cleared in vm_map_entry_copy().
         * "use_pmap" should stay the same as before (if it hasn't been reset
         * to TRUE when we cleared "iokit_acct").
         */
        assert(!new_entry->iokit_acct);

        /*
         *      If old entry's inheritence is VM_INHERIT_NONE,
         *      the new entry is for corpse fork, remove the
         *      write permission from the new entry.
         */
        if (old_entry->inheritance == VM_INHERIT_NONE) {
                new_entry->protection &= ~VM_PROT_WRITE;
                new_entry->max_protection &= ~VM_PROT_WRITE;
        }

        /*
         *      Insert the entry into the new map -- we
         *      know we're inserting at the end of the new
         *      map.
         */

        vm_map_store_entry_link(new_map, vm_map_last_entry(new_map), new_entry,
            VM_MAP_KERNEL_FLAGS_NONE);

        /*
         *      Update the physical map
         */

        if (old_entry->is_sub_map) {
                /* Bill Angell pmap support goes here */
        } else {
                pmap_copy(new_map->pmap, old_map->pmap, new_entry->vme_start,
                    old_entry->vme_end - old_entry->vme_start,
                    old_entry->vme_start);
        }
}

static boolean_t
vm_map_fork_copy(
        vm_map_t        old_map,
        vm_map_entry_t  *old_entry_p,
        vm_map_t        new_map,
        int             vm_map_copyin_flags)
{
        vm_map_entry_t old_entry = *old_entry_p;
        vm_map_size_t entry_size = old_entry->vme_end - old_entry->vme_start;
        vm_map_offset_t start = old_entry->vme_start;
        vm_map_copy_t copy;
        vm_map_entry_t last = vm_map_last_entry(new_map);

        vm_map_unlock(old_map);
        /*
         *      Use maxprot version of copyin because we
         *      care about whether this memory can ever
         *      be accessed, not just whether it's accessible
         *      right now.
         */
        vm_map_copyin_flags |= VM_MAP_COPYIN_USE_MAXPROT;
        if (vm_map_copyin_internal(old_map, start, entry_size,
            vm_map_copyin_flags, &copy)
            != KERN_SUCCESS) {
                /*
                 *      The map might have changed while it
                 *      was unlocked, check it again.  Skip
                 *      any blank space or permanently
                 *      unreadable region.
                 */
                vm_map_lock(old_map);
                if (!vm_map_lookup_entry(old_map, start, &last) ||
                    (last->max_protection & VM_PROT_READ) == VM_PROT_NONE) {
                        last = last->vme_next;
                }
                *old_entry_p = last;

                /*
                 * XXX  For some error returns, want to
                 * XXX  skip to the next element.  Note
                 *      that INVALID_ADDRESS and
                 *      PROTECTION_FAILURE are handled above.
                 */

                return FALSE;
        }

        /*
         * Assert that the vm_map_copy is coming from the right
         * zone and hasn't been forged
         */
        vm_map_copy_require(copy);

        /*
         *      Insert the copy into the new map
         */
        vm_map_copy_insert(new_map, last, copy);

        /*
         *      Pick up the traversal at the end of
         *      the copied region.
         */

        vm_map_lock(old_map);
        start += entry_size;
        if (!vm_map_lookup_entry(old_map, start, &last)) {
                last = last->vme_next;
        } else {
                if (last->vme_start == start) {
                        /*
                         * No need to clip here and we don't
                         * want to cause any unnecessary
                         * unnesting...
                         */
                } else {
                        vm_map_clip_start(old_map, last, start);
                }
        }
        *old_entry_p = last;

        return TRUE;
}

/*
 *      vm_map_fork:
 *
 *      Create and return a new map based on the old
 *      map, according to the inheritance values on the
 *      regions in that map and the options.
 *
 *      The source map must not be locked.
 */
vm_map_t
vm_map_fork(
        ledger_t        ledger,
        vm_map_t        old_map,
        int             options)
{
        pmap_t          new_pmap;
        vm_map_t        new_map;
        vm_map_entry_t  old_entry;
        vm_map_size_t   new_size = 0, entry_size;
        vm_map_entry_t  new_entry;
        boolean_t       src_needs_copy;
        boolean_t       new_entry_needs_copy;
        boolean_t       pmap_is64bit;
        int             vm_map_copyin_flags;
        vm_inherit_t    old_entry_inheritance;
        int             map_create_options;
        kern_return_t   footprint_collect_kr;

        if (options & ~(VM_MAP_FORK_SHARE_IF_INHERIT_NONE |
            VM_MAP_FORK_PRESERVE_PURGEABLE |
            VM_MAP_FORK_CORPSE_FOOTPRINT)) {
                /* unsupported option */
                return VM_MAP_NULL;
        }

        pmap_is64bit =
#if defined(__i386__) || defined(__x86_64__)
            old_map->pmap->pm_task_map != TASK_MAP_32BIT;
#elif defined(__arm64__)
            old_map->pmap->max == MACH_VM_MAX_ADDRESS;
#elif defined(__arm__)
            FALSE;
#else
#error Unknown architecture.
#endif

        unsigned int pmap_flags = 0;
        pmap_flags |= pmap_is64bit ? PMAP_CREATE_64BIT : 0;
#if defined(HAS_APPLE_PAC)
        pmap_flags |= old_map->pmap->disable_jop ? PMAP_CREATE_DISABLE_JOP : 0;
#endif
#if PMAP_CREATE_FORCE_4K_PAGES
        if (VM_MAP_PAGE_SIZE(old_map) == FOURK_PAGE_SIZE &&
            PAGE_SIZE != FOURK_PAGE_SIZE) {
                pmap_flags |= PMAP_CREATE_FORCE_4K_PAGES;
        }
#endif /* PMAP_CREATE_FORCE_4K_PAGES */
        new_pmap = pmap_create_options(ledger, (vm_map_size_t) 0, pmap_flags);

        vm_map_reference_swap(old_map);
        vm_map_lock(old_map);

        map_create_options = 0;
        if (old_map->hdr.entries_pageable) {
                map_create_options |= VM_MAP_CREATE_PAGEABLE;
        }
        if (options & VM_MAP_FORK_CORPSE_FOOTPRINT) {
                map_create_options |= VM_MAP_CREATE_CORPSE_FOOTPRINT;
                footprint_collect_kr = KERN_SUCCESS;
        }
        new_map = vm_map_create_options(new_pmap,
            old_map->min_offset,
            old_map->max_offset,
            map_create_options);
        /* inherit cs_enforcement */
        vm_map_cs_enforcement_set(new_map, old_map->cs_enforcement);
        vm_map_lock(new_map);
        vm_commit_pagezero_status(new_map);
        /* inherit the parent map's page size */
        vm_map_set_page_shift(new_map, VM_MAP_PAGE_SHIFT(old_map));
        for (
                old_entry = vm_map_first_entry(old_map);
                old_entry != vm_map_to_entry(old_map);
                ) {
                entry_size = old_entry->vme_end - old_entry->vme_start;

                old_entry_inheritance = old_entry->inheritance;
                /*
                 * If caller used the VM_MAP_FORK_SHARE_IF_INHERIT_NONE option
                 * share VM_INHERIT_NONE entries that are not backed by a
                 * device pager.
                 */
                if (old_entry_inheritance == VM_INHERIT_NONE &&
                    (options & VM_MAP_FORK_SHARE_IF_INHERIT_NONE) &&
                    (old_entry->protection & VM_PROT_READ) &&
                    !(!old_entry->is_sub_map &&
                    VME_OBJECT(old_entry) != NULL &&
                    VME_OBJECT(old_entry)->pager != NULL &&
                    is_device_pager_ops(
                            VME_OBJECT(old_entry)->pager->mo_pager_ops))) {
                        old_entry_inheritance = VM_INHERIT_SHARE;
                }

                if (old_entry_inheritance != VM_INHERIT_NONE &&
                    (options & VM_MAP_FORK_CORPSE_FOOTPRINT) &&
                    footprint_collect_kr == KERN_SUCCESS) {
                        /*
                         * The corpse won't have old_map->pmap to query
                         * footprint information, so collect that data now
                         * and store it in new_map->vmmap_corpse_footprint
                         * for later autopsy.
                         */
                        footprint_collect_kr =
                            vm_map_corpse_footprint_collect(old_map,
                            old_entry,
                            new_map);
                }

                switch (old_entry_inheritance) {
                case VM_INHERIT_NONE:
                        break;

                case VM_INHERIT_SHARE:
                        vm_map_fork_share(old_map, old_entry, new_map);
                        new_size += entry_size;
                        break;

                case VM_INHERIT_COPY:

                        /*
                         *      Inline the copy_quickly case;
                         *      upon failure, fall back on call
                         *      to vm_map_fork_copy.
                         */

                        if (old_entry->is_sub_map) {
                                break;
                        }
                        if ((old_entry->wired_count != 0) ||
                            ((VME_OBJECT(old_entry) != NULL) &&
                            (VME_OBJECT(old_entry)->true_share))) {
                                goto slow_vm_map_fork_copy;
                        }

                        new_entry = vm_map_entry_create(new_map, FALSE); /* never the kernel map or descendants */
                        vm_map_entry_copy(old_map, new_entry, old_entry);

                        if (new_entry->used_for_jit == TRUE && new_map->jit_entry_exists == FALSE) {
                                new_map->jit_entry_exists = TRUE;
                        }

                        if (new_entry->is_sub_map) {
                                /* clear address space specifics */
                                new_entry->use_pmap = FALSE;
                        } else {
                                /*
                                 * We're dealing with a copy-on-write operation,
                                 * so the resulting mapping should not inherit
                                 * the original mapping's accounting settings.
                                 * "iokit_acct" should have been cleared in
                                 * vm_map_entry_copy().
                                 * "use_pmap" should be reset to its default
                                 * (TRUE) so that the new mapping gets
                                 * accounted for in the task's memory footprint.
                                 */
                                assert(!new_entry->iokit_acct);
                                new_entry->use_pmap = TRUE;
                        }

                        if (!vm_object_copy_quickly(
                                    VME_OBJECT_PTR(new_entry),
                                    VME_OFFSET(old_entry),
                                    (old_entry->vme_end -
                                    old_entry->vme_start),
                                    &src_needs_copy,
                                    &new_entry_needs_copy)) {
                                vm_map_entry_dispose(new_map, new_entry);
                                goto slow_vm_map_fork_copy;
                        }

                        /*
                         *      Handle copy-on-write obligations
                         */

                        if (src_needs_copy && !old_entry->needs_copy) {
                                vm_prot_t prot;

                                assert(!pmap_has_prot_policy(old_map->pmap, old_entry->translated_allow_execute, old_entry->protection));

                                prot = old_entry->protection & ~VM_PROT_WRITE;

                                if (override_nx(old_map, VME_ALIAS(old_entry))
                                    && prot) {
                                        prot |= VM_PROT_EXECUTE;
                                }

                                assert(!pmap_has_prot_policy(old_map->pmap, old_entry->translated_allow_execute, prot));

                                vm_object_pmap_protect(
                                        VME_OBJECT(old_entry),
                                        VME_OFFSET(old_entry),
                                        (old_entry->vme_end -
                                        old_entry->vme_start),
                                        ((old_entry->is_shared
                                        || old_map->mapped_in_other_pmaps)
                                        ? PMAP_NULL :
                                        old_map->pmap),
                                        VM_MAP_PAGE_SIZE(old_map),
                                        old_entry->vme_start,
                                        prot);

                                assert(old_entry->wired_count == 0);
                                old_entry->needs_copy = TRUE;
                        }
                        new_entry->needs_copy = new_entry_needs_copy;

                        /*
                         *      Insert the entry at the end
                         *      of the map.
                         */

                        vm_map_store_entry_link(new_map,
                            vm_map_last_entry(new_map),
                            new_entry,
                            VM_MAP_KERNEL_FLAGS_NONE);
                        new_size += entry_size;
                        break;

slow_vm_map_fork_copy:
                        vm_map_copyin_flags = 0;
                        if (options & VM_MAP_FORK_PRESERVE_PURGEABLE) {
                                vm_map_copyin_flags |=
                                    VM_MAP_COPYIN_PRESERVE_PURGEABLE;
                        }
                        if (vm_map_fork_copy(old_map,
                            &old_entry,
                            new_map,
                            vm_map_copyin_flags)) {
                                new_size += entry_size;
                        }
                        continue;
                }
                old_entry = old_entry->vme_next;
        }

#if defined(__arm64__)
        pmap_insert_sharedpage(new_map->pmap);
#endif /* __arm64__ */

        new_map->size = new_size;

        if (options & VM_MAP_FORK_CORPSE_FOOTPRINT) {
                vm_map_corpse_footprint_collect_done(new_map);
        }

        /* Propagate JIT entitlement for the pmap layer. */
        if (pmap_get_jit_entitled(old_map->pmap)) {
                /* Tell the pmap that it supports JIT. */
                pmap_set_jit_entitled(new_map->pmap);
        }

        vm_map_unlock(new_map);
        vm_map_unlock(old_map);
        vm_map_deallocate(old_map);

        return new_map;
}

/*
 * vm_map_exec:
 *
 *      Setup the "new_map" with the proper execution environment according
 *      to the type of executable (platform, 64bit, chroot environment).
 *      Map the comm page and shared region, etc...
 */
kern_return_t
vm_map_exec(
        vm_map_t        new_map,
        task_t          task,
        boolean_t       is64bit,
        void            *fsroot,
        cpu_type_t      cpu,
        cpu_subtype_t   cpu_subtype,
        boolean_t       reslide)
{
        SHARED_REGION_TRACE_DEBUG(
                ("shared_region: task %p: vm_map_exec(%p,%p,%p,0x%x,0x%x): ->\n",
                (void *)VM_KERNEL_ADDRPERM(current_task()),
                (void *)VM_KERNEL_ADDRPERM(new_map),
                (void *)VM_KERNEL_ADDRPERM(task),
                (void *)VM_KERNEL_ADDRPERM(fsroot),
                cpu,
                cpu_subtype));
        (void) vm_commpage_enter(new_map, task, is64bit);

        (void) vm_shared_region_enter(new_map, task, is64bit, fsroot, cpu, cpu_subtype, reslide);

        SHARED_REGION_TRACE_DEBUG(
                ("shared_region: task %p: vm_map_exec(%p,%p,%p,0x%x,0x%x): <-\n",
                (void *)VM_KERNEL_ADDRPERM(current_task()),
                (void *)VM_KERNEL_ADDRPERM(new_map),
                (void *)VM_KERNEL_ADDRPERM(task),
                (void *)VM_KERNEL_ADDRPERM(fsroot),
                cpu,
                cpu_subtype));

        /*
         * Some devices have region(s) of memory that shouldn't get allocated by
         * user processes. The following code creates dummy vm_map_entry_t's for each
         * of the regions that needs to be reserved to prevent any allocations in
         * those regions.
         */
        kern_return_t kr = KERN_FAILURE;
        vm_map_kernel_flags_t vmk_flags = VM_MAP_KERNEL_FLAGS_NONE;
        vmk_flags.vmkf_permanent = TRUE;
        vmk_flags.vmkf_beyond_max = TRUE;

        struct vm_reserved_region *regions = NULL;
        size_t num_regions = ml_get_vm_reserved_regions(is64bit, &regions);
        assert((num_regions == 0) || (num_regions > 0 && regions != NULL));

        for (size_t i = 0; i < num_regions; ++i) {
                kr = vm_map_enter(
                        new_map,
                        &regions[i].vmrr_addr,
                        regions[i].vmrr_size,
                        (vm_map_offset_t)0,
                        VM_FLAGS_FIXED,
                        vmk_flags,
                        VM_KERN_MEMORY_NONE,
                        VM_OBJECT_NULL,
                        (vm_object_offset_t)0,
                        FALSE,
                        VM_PROT_NONE,
                        VM_PROT_NONE,
                        VM_INHERIT_NONE);

                if (kr != KERN_SUCCESS) {
                        panic("Failed to reserve %s region in user map %p %d", regions[i].vmrr_name, new_map, kr);
                }
        }

        new_map->reserved_regions = (num_regions ? TRUE : FALSE);

        return KERN_SUCCESS;
}

/*
 *      vm_map_lookup_locked:
 *
 *      Finds the VM object, offset, and
 *      protection for a given virtual address in the
 *      specified map, assuming a page fault of the
 *      type specified.
 *
 *      Returns the (object, offset, protection) for
 *      this address, whether it is wired down, and whether
 *      this map has the only reference to the data in question.
 *      In order to later verify this lookup, a "version"
 *      is returned.
 *      If contended != NULL, *contended will be set to
 *      true iff the thread had to spin or block to acquire
 *      an exclusive lock.
 *
 *      The map MUST be locked by the caller and WILL be
 *      locked on exit.  In order to guarantee the
 *      existence of the returned object, it is returned
 *      locked.
 *
 *      If a lookup is requested with "write protection"
 *      specified, the map may be changed to perform virtual
 *      copying operations, although the data referenced will
 *      remain the same.
 */
kern_return_t
vm_map_lookup_locked(
        vm_map_t                *var_map,       /* IN/OUT */
        vm_map_offset_t         vaddr,
        vm_prot_t               fault_type,
        int                     object_lock_type,
        vm_map_version_t        *out_version,   /* OUT */
        vm_object_t             *object,        /* OUT */
        vm_object_offset_t      *offset,        /* OUT */
        vm_prot_t               *out_prot,      /* OUT */
        boolean_t               *wired,         /* OUT */
        vm_object_fault_info_t  fault_info,     /* OUT */
        vm_map_t                *real_map,      /* OUT */
        bool                    *contended)     /* OUT */
{
        vm_map_entry_t                  entry;
        vm_map_t                        map = *var_map;
        vm_map_t                        old_map = *var_map;
        vm_map_t                        cow_sub_map_parent = VM_MAP_NULL;
        vm_map_offset_t                 cow_parent_vaddr = 0;
        vm_map_offset_t                 old_start = 0;
        vm_map_offset_t                 old_end = 0;
        vm_prot_t                       prot;
        boolean_t                       mask_protections;
        boolean_t                       force_copy;
        boolean_t                       no_force_copy_if_executable;
        vm_prot_t                       original_fault_type;
        vm_map_size_t                   fault_page_mask;

        /*
         * VM_PROT_MASK means that the caller wants us to use "fault_type"
         * as a mask against the mapping's actual protections, not as an
         * absolute value.
         */
        mask_protections = (fault_type & VM_PROT_IS_MASK) ? TRUE : FALSE;
        force_copy = (fault_type & VM_PROT_COPY) ? TRUE : FALSE;
        no_force_copy_if_executable = (fault_type & VM_PROT_COPY_FAIL_IF_EXECUTABLE) ? TRUE : FALSE;
        fault_type &= VM_PROT_ALL;
        original_fault_type = fault_type;
        if (contended) {
                *contended = false;
        }

        *real_map = map;

        fault_page_mask = MIN(VM_MAP_PAGE_MASK(map), PAGE_MASK);
        vaddr = VM_MAP_TRUNC_PAGE(vaddr, fault_page_mask);

RetryLookup:
        fault_type = original_fault_type;

        /*
         *      If the map has an interesting hint, try it before calling
         *      full blown lookup routine.
         */
        entry = map->hint;

        if ((entry == vm_map_to_entry(map)) ||
            (vaddr < entry->vme_start) || (vaddr >= entry->vme_end)) {
                vm_map_entry_t  tmp_entry;

                /*
                 *      Entry was either not a valid hint, or the vaddr
                 *      was not contained in the entry, so do a full lookup.
                 */
                if (!vm_map_lookup_entry(map, vaddr, &tmp_entry)) {
                        if ((cow_sub_map_parent) && (cow_sub_map_parent != map)) {
                                vm_map_unlock(cow_sub_map_parent);
                        }
                        if ((*real_map != map)
                            && (*real_map != cow_sub_map_parent)) {
                                vm_map_unlock(*real_map);
                        }
                        return KERN_INVALID_ADDRESS;
                }

                entry = tmp_entry;
        }
        if (map == old_map) {
                old_start = entry->vme_start;
                old_end = entry->vme_end;
        }

        /*
         *      Handle submaps.  Drop lock on upper map, submap is
         *      returned locked.
         */

submap_recurse:
        if (entry->is_sub_map) {
                vm_map_offset_t         local_vaddr;
                vm_map_offset_t         end_delta;
                vm_map_offset_t         start_delta;
                vm_map_entry_t          submap_entry, saved_submap_entry;
                vm_object_offset_t      submap_entry_offset;
                vm_object_size_t        submap_entry_size;
                vm_prot_t               subentry_protection;
                vm_prot_t               subentry_max_protection;
                boolean_t               subentry_no_copy_on_read;
                boolean_t               mapped_needs_copy = FALSE;
                vm_map_version_t        version;

                assertf(VM_MAP_PAGE_SHIFT(VME_SUBMAP(entry)) >= VM_MAP_PAGE_SHIFT(map),
                    "map %p (%d) entry %p submap %p (%d)\n",
                    map, VM_MAP_PAGE_SHIFT(map), entry,
                    VME_SUBMAP(entry), VM_MAP_PAGE_SHIFT(VME_SUBMAP(entry)));

                local_vaddr = vaddr;

                if ((entry->use_pmap &&
                    !((fault_type & VM_PROT_WRITE) ||
                    force_copy))) {
                        /* if real_map equals map we unlock below */
                        if ((*real_map != map) &&
                            (*real_map != cow_sub_map_parent)) {
                                vm_map_unlock(*real_map);
                        }
                        *real_map = VME_SUBMAP(entry);
                }

                if (entry->needs_copy &&
                    ((fault_type & VM_PROT_WRITE) ||
                    force_copy)) {
                        if (!mapped_needs_copy) {
                                if (vm_map_lock_read_to_write(map)) {
                                        vm_map_lock_read(map);
                                        *real_map = map;
                                        goto RetryLookup;
                                }
                                vm_map_lock_read(VME_SUBMAP(entry));
                                *var_map = VME_SUBMAP(entry);
                                cow_sub_map_parent = map;
                                /* reset base to map before cow object */
                                /* this is the map which will accept   */
                                /* the new cow object */
                                old_start = entry->vme_start;
                                old_end = entry->vme_end;
                                cow_parent_vaddr = vaddr;
                                mapped_needs_copy = TRUE;
                        } else {
                                vm_map_lock_read(VME_SUBMAP(entry));
                                *var_map = VME_SUBMAP(entry);
                                if ((cow_sub_map_parent != map) &&
                                    (*real_map != map)) {
                                        vm_map_unlock(map);
                                }
                        }
                } else {
                        vm_map_lock_read(VME_SUBMAP(entry));
                        *var_map = VME_SUBMAP(entry);
                        /* leave map locked if it is a target */
                        /* cow sub_map above otherwise, just  */
                        /* follow the maps down to the object */
                        /* here we unlock knowing we are not  */
                        /* revisiting the map.  */
                        if ((*real_map != map) && (map != cow_sub_map_parent)) {
                                vm_map_unlock_read(map);
                        }
                }

                map = *var_map;

                /* calculate the offset in the submap for vaddr */
                local_vaddr = (local_vaddr - entry->vme_start) + VME_OFFSET(entry);
                assertf(VM_MAP_PAGE_ALIGNED(local_vaddr, fault_page_mask),
                    "local_vaddr 0x%llx entry->vme_start 0x%llx fault_page_mask 0x%llx\n",
                    (uint64_t)local_vaddr, (uint64_t)entry->vme_start, (uint64_t)fault_page_mask);

RetrySubMap:
                if (!vm_map_lookup_entry(map, local_vaddr, &submap_entry)) {
                        if ((cow_sub_map_parent) && (cow_sub_map_parent != map)) {
                                vm_map_unlock(cow_sub_map_parent);
                        }
                        if ((*real_map != map)
                            && (*real_map != cow_sub_map_parent)) {
                                vm_map_unlock(*real_map);
                        }
                        *real_map = map;
                        return KERN_INVALID_ADDRESS;
                }

                /* find the attenuated shadow of the underlying object */
                /* on our target map */

                /* in english the submap object may extend beyond the     */
                /* region mapped by the entry or, may only fill a portion */
                /* of it.  For our purposes, we only care if the object   */
                /* doesn't fill.  In this case the area which will        */
                /* ultimately be clipped in the top map will only need    */
                /* to be as big as the portion of the underlying entry    */
                /* which is mapped */
                start_delta = submap_entry->vme_start > VME_OFFSET(entry) ?
                    submap_entry->vme_start - VME_OFFSET(entry) : 0;

                end_delta =
                    (VME_OFFSET(entry) + start_delta + (old_end - old_start)) <=
                    submap_entry->vme_end ?
                    0 : (VME_OFFSET(entry) +
                    (old_end - old_start))
                    - submap_entry->vme_end;

                old_start += start_delta;
                old_end -= end_delta;

                if (submap_entry->is_sub_map) {
                        entry = submap_entry;
                        vaddr = local_vaddr;
                        goto submap_recurse;
                }

                if (((fault_type & VM_PROT_WRITE) ||
                    force_copy)
                    && cow_sub_map_parent) {
                        vm_object_t     sub_object, copy_object;
                        vm_object_offset_t copy_offset;
                        vm_map_offset_t local_start;
                        vm_map_offset_t local_end;
                        boolean_t       copied_slowly = FALSE;
                        vm_object_offset_t copied_slowly_phys_offset = 0;
                        kern_return_t   kr = KERN_SUCCESS;

                        if (vm_map_lock_read_to_write(map)) {
                                vm_map_lock_read(map);
                                old_start -= start_delta;
                                old_end += end_delta;
                                goto RetrySubMap;
                        }


                        sub_object = VME_OBJECT(submap_entry);
                        if (sub_object == VM_OBJECT_NULL) {
                                sub_object =
                                    vm_object_allocate(
                                        (vm_map_size_t)
                                        (submap_entry->vme_end -
                                        submap_entry->vme_start));
                                VME_OBJECT_SET(submap_entry, sub_object);
                                VME_OFFSET_SET(submap_entry, 0);
                                assert(!submap_entry->is_sub_map);
                                assert(submap_entry->use_pmap);
                        }
                        local_start =  local_vaddr -
                            (cow_parent_vaddr - old_start);
                        local_end = local_vaddr +
                            (old_end - cow_parent_vaddr);
                        vm_map_clip_start(map, submap_entry, local_start);
                        vm_map_clip_end(map, submap_entry, local_end);
                        if (submap_entry->is_sub_map) {
                                /* unnesting was done when clipping */
                                assert(!submap_entry->use_pmap);
                        }

                        /* This is the COW case, lets connect */
                        /* an entry in our space to the underlying */
                        /* object in the submap, bypassing the  */
                        /* submap. */

                        if (submap_entry->wired_count != 0 ||
                            (sub_object->copy_strategy !=
                            MEMORY_OBJECT_COPY_SYMMETRIC)) {
                                if ((submap_entry->protection & VM_PROT_EXECUTE) &&
                                    no_force_copy_if_executable) {
//                                      printf("FBDP map %p entry %p start 0x%llx end 0x%llx wired %d strat %d\n", map, submap_entry, (uint64_t)local_start, (uint64_t)local_end, submap_entry->wired_count, sub_object->copy_strategy);
                                        if ((cow_sub_map_parent) && (cow_sub_map_parent != map)) {
                                                vm_map_unlock(cow_sub_map_parent);
                                        }
                                        if ((*real_map != map)
                                            && (*real_map != cow_sub_map_parent)) {
                                                vm_map_unlock(*real_map);
                                        }
                                        *real_map = map;
                                        vm_map_lock_write_to_read(map);
                                        kr = KERN_PROTECTION_FAILURE;
                                        DTRACE_VM4(submap_no_copy_executable,
                                            vm_map_t, map,
                                            vm_object_offset_t, submap_entry_offset,
                                            vm_object_size_t, submap_entry_size,
                                            int, kr);
                                        return kr;
                                }

                                vm_object_reference(sub_object);

                                assertf(VM_MAP_PAGE_ALIGNED(VME_OFFSET(submap_entry), VM_MAP_PAGE_MASK(map)),
                                    "submap_entry %p offset 0x%llx\n",
                                    submap_entry, VME_OFFSET(submap_entry));
                                submap_entry_offset = VME_OFFSET(submap_entry);
                                submap_entry_size = submap_entry->vme_end - submap_entry->vme_start;

                                DTRACE_VM6(submap_copy_slowly,
                                    vm_map_t, cow_sub_map_parent,
                                    vm_map_offset_t, vaddr,
                                    vm_map_t, map,
                                    vm_object_size_t, submap_entry_size,
                                    int, submap_entry->wired_count,
                                    int, sub_object->copy_strategy);

                                saved_submap_entry = submap_entry;
                                version.main_timestamp = map->timestamp;
                                vm_map_unlock(map); /* Increments timestamp by 1 */
                                submap_entry = VM_MAP_ENTRY_NULL;

                                vm_object_lock(sub_object);
                                kr = vm_object_copy_slowly(sub_object,
                                    submap_entry_offset,
                                    submap_entry_size,
                                    FALSE,
                                    &copy_object);
                                copied_slowly = TRUE;
                                /* 4k: account for extra offset in physical page */
                                copied_slowly_phys_offset = submap_entry_offset - vm_object_trunc_page(submap_entry_offset);
                                vm_object_deallocate(sub_object);

                                vm_map_lock(map);

                                if (kr != KERN_SUCCESS &&
                                    kr != KERN_MEMORY_RESTART_COPY) {
                                        if ((cow_sub_map_parent) && (cow_sub_map_parent != map)) {
                                                vm_map_unlock(cow_sub_map_parent);
                                        }
                                        if ((*real_map != map)
                                            && (*real_map != cow_sub_map_parent)) {
                                                vm_map_unlock(*real_map);
                                        }
                                        *real_map = map;
                                        vm_object_deallocate(copy_object);
                                        copy_object = VM_OBJECT_NULL;
                                        vm_map_lock_write_to_read(map);
                                        DTRACE_VM4(submap_copy_slowly,
                                            vm_object_t, sub_object,
                                            vm_object_offset_t, submap_entry_offset,
                                            vm_object_size_t, submap_entry_size,
                                            int, kr);
                                        return kr;
                                }

                                if ((kr == KERN_SUCCESS) &&
                                    (version.main_timestamp + 1) == map->timestamp) {
                                        submap_entry = saved_submap_entry;
                                } else {
                                        saved_submap_entry = NULL;
                                        old_start -= start_delta;
                                        old_end += end_delta;
                                        vm_object_deallocate(copy_object);
                                        copy_object = VM_OBJECT_NULL;
                                        vm_map_lock_write_to_read(map);
                                        goto RetrySubMap;
                                }
                        } else {
                                /* set up shadow object */
                                copy_object = sub_object;
                                vm_object_lock(sub_object);
                                vm_object_reference_locked(sub_object);
                                sub_object->shadowed = TRUE;
                                vm_object_unlock(sub_object);

                                assert(submap_entry->wired_count == 0);
                                submap_entry->needs_copy = TRUE;

                                prot = submap_entry->protection;
                                assert(!pmap_has_prot_policy(map->pmap, submap_entry->translated_allow_execute, prot));
                                prot = prot & ~VM_PROT_WRITE;
                                assert(!pmap_has_prot_policy(map->pmap, submap_entry->translated_allow_execute, prot));

                                if (override_nx(old_map,
                                    VME_ALIAS(submap_entry))
                                    && prot) {
                                        prot |= VM_PROT_EXECUTE;
                                }

                                vm_object_pmap_protect(
                                        sub_object,
                                        VME_OFFSET(submap_entry),
                                        submap_entry->vme_end -
                                        submap_entry->vme_start,
                                        (submap_entry->is_shared
                                        || map->mapped_in_other_pmaps) ?
                                        PMAP_NULL : map->pmap,
                                        VM_MAP_PAGE_SIZE(map),
                                        submap_entry->vme_start,
                                        prot);
                        }

                        /*
                         * Adjust the fault offset to the submap entry.
                         */
                        copy_offset = (local_vaddr -
                            submap_entry->vme_start +
                            VME_OFFSET(submap_entry));

                        /* This works diffently than the   */
                        /* normal submap case. We go back  */
                        /* to the parent of the cow map and*/
                        /* clip out the target portion of  */
                        /* the sub_map, substituting the   */
                        /* new copy object,                */

                        subentry_protection = submap_entry->protection;
                        subentry_max_protection = submap_entry->max_protection;
                        subentry_no_copy_on_read = submap_entry->vme_no_copy_on_read;
                        vm_map_unlock(map);
                        submap_entry = NULL; /* not valid after map unlock */

                        local_start = old_start;
                        local_end = old_end;
                        map = cow_sub_map_parent;
                        *var_map = cow_sub_map_parent;
                        vaddr = cow_parent_vaddr;
                        cow_sub_map_parent = NULL;

                        if (!vm_map_lookup_entry(map,
                            vaddr, &entry)) {
                                if ((cow_sub_map_parent) && (cow_sub_map_parent != map)) {
                                        vm_map_unlock(cow_sub_map_parent);
                                }
                                if ((*real_map != map)
                                    && (*real_map != cow_sub_map_parent)) {
                                        vm_map_unlock(*real_map);
                                }
                                *real_map = map;
                                vm_object_deallocate(
                                        copy_object);
                                copy_object = VM_OBJECT_NULL;
                                vm_map_lock_write_to_read(map);
                                DTRACE_VM4(submap_lookup_post_unlock,
                                    uint64_t, (uint64_t)entry->vme_start,
                                    uint64_t, (uint64_t)entry->vme_end,
                                    vm_map_offset_t, vaddr,
                                    int, copied_slowly);
                                return KERN_INVALID_ADDRESS;
                        }

                        /* clip out the portion of space */
                        /* mapped by the sub map which   */
                        /* corresponds to the underlying */
                        /* object */

                        /*
                         * Clip (and unnest) the smallest nested chunk
                         * possible around the faulting address...
                         */
                        local_start = vaddr & ~(pmap_shared_region_size_min(map->pmap) - 1);
                        local_end = local_start + pmap_shared_region_size_min(map->pmap);
                        /*
                         * ... but don't go beyond the "old_start" to "old_end"
                         * range, to avoid spanning over another VM region
                         * with a possibly different VM object and/or offset.
                         */
                        if (local_start < old_start) {
                                local_start = old_start;
                        }
                        if (local_end > old_end) {
                                local_end = old_end;
                        }
                        /*
                         * Adjust copy_offset to the start of the range.
                         */
                        copy_offset -= (vaddr - local_start);

                        vm_map_clip_start(map, entry, local_start);
                        vm_map_clip_end(map, entry, local_end);
                        if (entry->is_sub_map) {
                                /* unnesting was done when clipping */
                                assert(!entry->use_pmap);
                        }

                        /* substitute copy object for */
                        /* shared map entry           */
                        vm_map_deallocate(VME_SUBMAP(entry));
                        assert(!entry->iokit_acct);
                        entry->is_sub_map = FALSE;
                        entry->use_pmap = TRUE;
                        VME_OBJECT_SET(entry, copy_object);

                        /* propagate the submap entry's protections */
                        if (entry->protection != VM_PROT_READ) {
                                /*
                                 * Someone has already altered the top entry's
                                 * protections via vm_protect(VM_PROT_COPY).
                                 * Respect these new values and ignore the
                                 * submap entry's protections.
                                 */
                        } else {
                                /*
                                 * Regular copy-on-write: propagate the submap
                                 * entry's protections to the top map entry.
                                 */
                                entry->protection |= subentry_protection;
                        }
                        entry->max_protection |= subentry_max_protection;
                        /* propagate no_copy_on_read */
                        entry->vme_no_copy_on_read = subentry_no_copy_on_read;

                        if ((entry->protection & VM_PROT_WRITE) &&
                            (entry->protection & VM_PROT_EXECUTE) &&
#if XNU_TARGET_OS_OSX
                            map->pmap != kernel_pmap &&
                            (vm_map_cs_enforcement(map)
#if __arm64__
                            || !VM_MAP_IS_EXOTIC(map)
#endif /* __arm64__ */
                            ) &&
#endif /* XNU_TARGET_OS_OSX */
                            !(entry->used_for_jit) &&
                            VM_MAP_POLICY_WX_STRIP_X(map)) {
                                DTRACE_VM3(cs_wx,
                                    uint64_t, (uint64_t)entry->vme_start,
                                    uint64_t, (uint64_t)entry->vme_end,
                                    vm_prot_t, entry->protection);
                                printf("CODE SIGNING: %d[%s] %s can't have both write and exec at the same time\n",
                                    proc_selfpid(),
                                    (current_task()->bsd_info
                                    ? proc_name_address(current_task()->bsd_info)
                                    : "?"),
                                    __FUNCTION__);
                                entry->protection &= ~VM_PROT_EXECUTE;
                        }

                        if (copied_slowly) {
                                VME_OFFSET_SET(entry, local_start - old_start + copied_slowly_phys_offset);
                                entry->needs_copy = FALSE;
                                entry->is_shared = FALSE;
                        } else {
                                VME_OFFSET_SET(entry, copy_offset);
                                assert(entry->wired_count == 0);
                                entry->needs_copy = TRUE;
                                if (entry->inheritance == VM_INHERIT_SHARE) {
                                        entry->inheritance = VM_INHERIT_COPY;
                                }
                                if (map != old_map) {
                                        entry->is_shared = TRUE;
                                }
                        }
                        if (entry->inheritance == VM_INHERIT_SHARE) {
                                entry->inheritance = VM_INHERIT_COPY;
                        }

                        vm_map_lock_write_to_read(map);
                } else {
                        if ((cow_sub_map_parent)
                            && (cow_sub_map_parent != *real_map)
                            && (cow_sub_map_parent != map)) {
                                vm_map_unlock(cow_sub_map_parent);
                        }
                        entry = submap_entry;
                        vaddr = local_vaddr;
                }
        }

        /*
         *      Check whether this task is allowed to have
         *      this page.
         */

        prot = entry->protection;

        if (override_nx(old_map, VME_ALIAS(entry)) && prot) {
                /*
                 * HACK -- if not a stack, then allow execution
                 */
                prot |= VM_PROT_EXECUTE;
        }

        if (mask_protections) {
                fault_type &= prot;
                if (fault_type == VM_PROT_NONE) {
                        goto protection_failure;
                }
        }
        if (((fault_type & prot) != fault_type)
#if __arm64__
            /* prefetch abort in execute-only page */
            && !(prot == VM_PROT_EXECUTE && fault_type == (VM_PROT_READ | VM_PROT_EXECUTE))
#endif
            ) {
protection_failure:
                if (*real_map != map) {
                        vm_map_unlock(*real_map);
                }
                *real_map = map;

                if ((fault_type & VM_PROT_EXECUTE) && prot) {
                        log_stack_execution_failure((addr64_t)vaddr, prot);
                }

                DTRACE_VM2(prot_fault, int, 1, (uint64_t *), NULL);
                return KERN_PROTECTION_FAILURE;
        }

        /*
         *      If this page is not pageable, we have to get
         *      it for all possible accesses.
         */

        *wired = (entry->wired_count != 0);
        if (*wired) {
                fault_type = prot;
        }

        /*
         *      If the entry was copy-on-write, we either ...
         */

        if (entry->needs_copy) {
                /*
                 *      If we want to write the page, we may as well
                 *      handle that now since we've got the map locked.
                 *
                 *      If we don't need to write the page, we just
                 *      demote the permissions allowed.
                 */

                if ((fault_type & VM_PROT_WRITE) || *wired || force_copy) {
                        /*
                         *      Make a new object, and place it in the
                         *      object chain.  Note that no new references
                         *      have appeared -- one just moved from the
                         *      map to the new object.
                         */

                        if (vm_map_lock_read_to_write(map)) {
                                vm_map_lock_read(map);
                                goto RetryLookup;
                        }

                        if (VME_OBJECT(entry)->shadowed == FALSE) {
                                vm_object_lock(VME_OBJECT(entry));
                                VME_OBJECT(entry)->shadowed = TRUE;
                                vm_object_unlock(VME_OBJECT(entry));
                        }
                        VME_OBJECT_SHADOW(entry,
                            (vm_map_size_t) (entry->vme_end -
                            entry->vme_start));
                        entry->needs_copy = FALSE;

                        vm_map_lock_write_to_read(map);
                }
                if ((fault_type & VM_PROT_WRITE) == 0 && *wired == 0) {
                        /*
                         *      We're attempting to read a copy-on-write
                         *      page -- don't allow writes.
                         */

                        prot &= (~VM_PROT_WRITE);
                }
        }

        /*
         *      Create an object if necessary.
         */
        if (VME_OBJECT(entry) == VM_OBJECT_NULL) {
                if (vm_map_lock_read_to_write(map)) {
                        vm_map_lock_read(map);
                        goto RetryLookup;
                }

                VME_OBJECT_SET(entry,
                    vm_object_allocate(
                            (vm_map_size_t)(entry->vme_end -
                            entry->vme_start)));
                VME_OFFSET_SET(entry, 0);
                assert(entry->use_pmap);
                vm_map_lock_write_to_read(map);
        }

        /*
         *      Return the object/offset from this entry.  If the entry
         *      was copy-on-write or empty, it has been fixed up.  Also
         *      return the protection.
         */

        *offset = (vaddr - entry->vme_start) + VME_OFFSET(entry);
        *object = VME_OBJECT(entry);
        *out_prot = prot;
        KDBG_FILTERED(MACHDBG_CODE(DBG_MACH_WORKINGSET, VM_MAP_LOOKUP_OBJECT), VM_KERNEL_UNSLIDE_OR_PERM(*object), (unsigned long) VME_ALIAS(entry), 0, 0);

        if (fault_info) {
                fault_info->interruptible = THREAD_UNINT; /* for now... */
                /* ... the caller will change "interruptible" if needed */
                fault_info->cluster_size = 0;
                fault_info->user_tag = VME_ALIAS(entry);
                fault_info->pmap_options = 0;
                if (entry->iokit_acct ||
                    (!entry->is_sub_map && !entry->use_pmap)) {
                        fault_info->pmap_options |= PMAP_OPTIONS_ALT_ACCT;
                }
                fault_info->behavior = entry->behavior;
                fault_info->lo_offset = VME_OFFSET(entry);
                fault_info->hi_offset =
                    (entry->vme_end - entry->vme_start) + VME_OFFSET(entry);
                fault_info->no_cache  = entry->no_cache;
                fault_info->stealth = FALSE;
                fault_info->io_sync = FALSE;
                if (entry->used_for_jit ||
                    entry->vme_resilient_codesign) {
                        fault_info->cs_bypass = TRUE;
                } else {
                        fault_info->cs_bypass = FALSE;
                }
                fault_info->pmap_cs_associated = FALSE;
#if CONFIG_PMAP_CS
                if (entry->pmap_cs_associated) {
                        /*
                         * The pmap layer will validate this page
                         * before allowing it to be executed from.
                         */
                        fault_info->pmap_cs_associated = TRUE;
                }
#endif /* CONFIG_PMAP_CS */
                fault_info->mark_zf_absent = FALSE;
                fault_info->batch_pmap_op = FALSE;
                fault_info->resilient_media = entry->vme_resilient_media;
                fault_info->no_copy_on_read = entry->vme_no_copy_on_read;
                if (entry->translated_allow_execute) {
                        fault_info->pmap_options |= PMAP_OPTIONS_TRANSLATED_ALLOW_EXECUTE;
                }
        }

        /*
         *      Lock the object to prevent it from disappearing
         */
        if (object_lock_type == OBJECT_LOCK_EXCLUSIVE) {
                if (contended == NULL) {
                        vm_object_lock(*object);
                } else {
                        *contended = vm_object_lock_check_contended(*object);
                }
        } else {
                vm_object_lock_shared(*object);
        }

        /*
         *      Save the version number
         */

        out_version->main_timestamp = map->timestamp;

        return KERN_SUCCESS;
}


/*
 *      vm_map_verify:
 *
 *      Verifies that the map in question has not changed
 *      since the given version. The map has to be locked
 *      ("shared" mode is fine) before calling this function
 *      and it will be returned locked too.
 */
boolean_t
vm_map_verify(
        vm_map_t                map,
        vm_map_version_t        *version)       /* REF */
{
        boolean_t       result;

        vm_map_lock_assert_held(map);
        result = (map->timestamp == version->main_timestamp);

        return result;
}

/*
 *      TEMPORARYTEMPORARYTEMPORARYTEMPORARYTEMPORARYTEMPORARY
 *      Goes away after regular vm_region_recurse function migrates to
 *      64 bits
 *      vm_region_recurse: A form of vm_region which follows the
 *      submaps in a target map
 *
 */

kern_return_t
vm_map_region_recurse_64(
        vm_map_t                 map,
        vm_map_offset_t *address,               /* IN/OUT */
        vm_map_size_t           *size,                  /* OUT */
        natural_t               *nesting_depth, /* IN/OUT */
        vm_region_submap_info_64_t      submap_info,    /* IN/OUT */
        mach_msg_type_number_t  *count) /* IN/OUT */
{
        mach_msg_type_number_t  original_count;
        vm_region_extended_info_data_t  extended;
        vm_map_entry_t                  tmp_entry;
        vm_map_offset_t                 user_address;
        unsigned int                    user_max_depth;

        /*
         * "curr_entry" is the VM map entry preceding or including the
         * address we're looking for.
         * "curr_map" is the map or sub-map containing "curr_entry".
         * "curr_address" is the equivalent of the top map's "user_address"
         * in the current map.
         * "curr_offset" is the cumulated offset of "curr_map" in the
         * target task's address space.
         * "curr_depth" is the depth of "curr_map" in the chain of
         * sub-maps.
         *
         * "curr_max_below" and "curr_max_above" limit the range (around
         * "curr_address") we should take into account in the current (sub)map.
         * They limit the range to what's visible through the map entries
         * we've traversed from the top map to the current map.
         *
         */
        vm_map_entry_t                  curr_entry;
        vm_map_address_t                curr_address;
        vm_map_offset_t                 curr_offset;
        vm_map_t                        curr_map;
        unsigned int                    curr_depth;
        vm_map_offset_t                 curr_max_below, curr_max_above;
        vm_map_offset_t                 curr_skip;

        /*
         * "next_" is the same as "curr_" but for the VM region immediately
         * after the address we're looking for.  We need to keep track of this
         * too because we want to return info about that region if the
         * address we're looking for is not mapped.
         */
        vm_map_entry_t                  next_entry;
        vm_map_offset_t                 next_offset;
        vm_map_offset_t                 next_address;
        vm_map_t                        next_map;
        unsigned int                    next_depth;
        vm_map_offset_t                 next_max_below, next_max_above;
        vm_map_offset_t                 next_skip;

        boolean_t                       look_for_pages;
        vm_region_submap_short_info_64_t short_info;
        boolean_t                       do_region_footprint;
        int                             effective_page_size, effective_page_shift;

        if (map == VM_MAP_NULL) {
                /* no address space to work on */
                return KERN_INVALID_ARGUMENT;
        }

        effective_page_shift = vm_self_region_page_shift(map);
        effective_page_size = (1 << effective_page_shift);

        if (*count < VM_REGION_SUBMAP_SHORT_INFO_COUNT_64) {
                /*
                 * "info" structure is not big enough and
                 * would overflow
                 */
                return KERN_INVALID_ARGUMENT;
        }

        do_region_footprint = task_self_region_footprint();
        original_count = *count;

        if (original_count < VM_REGION_SUBMAP_INFO_V0_COUNT_64) {
                *count = VM_REGION_SUBMAP_SHORT_INFO_COUNT_64;
                look_for_pages = FALSE;
                short_info = (vm_region_submap_short_info_64_t) submap_info;
                submap_info = NULL;
        } else {
                look_for_pages = TRUE;
                *count = VM_REGION_SUBMAP_INFO_V0_COUNT_64;
                short_info = NULL;

                if (original_count >= VM_REGION_SUBMAP_INFO_V1_COUNT_64) {
                        *count = VM_REGION_SUBMAP_INFO_V1_COUNT_64;
                }
                if (original_count >= VM_REGION_SUBMAP_INFO_V2_COUNT_64) {
                        *count = VM_REGION_SUBMAP_INFO_V2_COUNT_64;
                }
        }

        user_address = *address;
        user_max_depth = *nesting_depth;

        if (not_in_kdp) {
                vm_map_lock_read(map);
        }

recurse_again:
        curr_entry = NULL;
        curr_map = map;
        curr_address = user_address;
        curr_offset = 0;
        curr_skip = 0;
        curr_depth = 0;
        curr_max_above = ((vm_map_offset_t) -1) - curr_address;
        curr_max_below = curr_address;

        next_entry = NULL;
        next_map = NULL;
        next_address = 0;
        next_offset = 0;
        next_skip = 0;
        next_depth = 0;
        next_max_above = (vm_map_offset_t) -1;
        next_max_below = (vm_map_offset_t) -1;

        for (;;) {
                if (vm_map_lookup_entry(curr_map,
                    curr_address,
                    &tmp_entry)) {
                        /* tmp_entry contains the address we're looking for */
                        curr_entry = tmp_entry;
                } else {
                        vm_map_offset_t skip;
                        /*
                         * The address is not mapped.  "tmp_entry" is the
                         * map entry preceding the address.  We want the next
                         * one, if it exists.
                         */
                        curr_entry = tmp_entry->vme_next;

                        if (curr_entry == vm_map_to_entry(curr_map) ||
                            (curr_entry->vme_start >=
                            curr_address + curr_max_above)) {
                                /* no next entry at this level: stop looking */
                                if (not_in_kdp) {
                                        vm_map_unlock_read(curr_map);
                                }
                                curr_entry = NULL;
                                curr_map = NULL;
                                curr_skip = 0;
                                curr_offset = 0;
                                curr_depth = 0;
                                curr_max_above = 0;
                                curr_max_below = 0;
                                break;
                        }

                        /* adjust current address and offset */
                        skip = curr_entry->vme_start - curr_address;
                        curr_address = curr_entry->vme_start;
                        curr_skip += skip;
                        curr_offset += skip;
                        curr_max_above -= skip;
                        curr_max_below = 0;
                }

                /*
                 * Is the next entry at this level closer to the address (or
                 * deeper in the submap chain) than the one we had
                 * so far ?
                 */
                tmp_entry = curr_entry->vme_next;
                if (tmp_entry == vm_map_to_entry(curr_map)) {
                        /* no next entry at this level */
                } else if (tmp_entry->vme_start >=
                    curr_address + curr_max_above) {
                        /*
                         * tmp_entry is beyond the scope of what we mapped of
                         * this submap in the upper level: ignore it.
                         */
                } else if ((next_entry == NULL) ||
                    (tmp_entry->vme_start + curr_offset <=
                    next_entry->vme_start + next_offset)) {
                        /*
                         * We didn't have a "next_entry" or this one is
                         * closer to the address we're looking for:
                         * use this "tmp_entry" as the new "next_entry".
                         */
                        if (next_entry != NULL) {
                                /* unlock the last "next_map" */
                                if (next_map != curr_map && not_in_kdp) {
                                        vm_map_unlock_read(next_map);
                                }
                        }
                        next_entry = tmp_entry;
                        next_map = curr_map;
                        next_depth = curr_depth;
                        next_address = next_entry->vme_start;
                        next_skip = curr_skip;
                        next_skip += (next_address - curr_address);
                        next_offset = curr_offset;
                        next_offset += (next_address - curr_address);
                        next_max_above = MIN(next_max_above, curr_max_above);
                        next_max_above = MIN(next_max_above,
                            next_entry->vme_end - next_address);
                        next_max_below = MIN(next_max_below, curr_max_below);
                        next_max_below = MIN(next_max_below,
                            next_address - next_entry->vme_start);
                }

                /*
                 * "curr_max_{above,below}" allow us to keep track of the
                 * portion of the submap that is actually mapped at this level:
                 * the rest of that submap is irrelevant to us, since it's not
                 * mapped here.
                 * The relevant portion of the map starts at
                 * "VME_OFFSET(curr_entry)" up to the size of "curr_entry".
                 */
                curr_max_above = MIN(curr_max_above,
                    curr_entry->vme_end - curr_address);
                curr_max_below = MIN(curr_max_below,
                    curr_address - curr_entry->vme_start);

                if (!curr_entry->is_sub_map ||
                    curr_depth >= user_max_depth) {
                        /*
                         * We hit a leaf map or we reached the maximum depth
                         * we could, so stop looking.  Keep the current map
                         * locked.
                         */
                        break;
                }

                /*
                 * Get down to the next submap level.
                 */

                /*
                 * Lock the next level and unlock the current level,
                 * unless we need to keep it locked to access the "next_entry"
                 * later.
                 */
                if (not_in_kdp) {
                        vm_map_lock_read(VME_SUBMAP(curr_entry));
                }
                if (curr_map == next_map) {
                        /* keep "next_map" locked in case we need it */
                } else {
                        /* release this map */
                        if (not_in_kdp) {
                                vm_map_unlock_read(curr_map);
                        }
                }

                /*
                 * Adjust the offset.  "curr_entry" maps the submap
                 * at relative address "curr_entry->vme_start" in the
                 * curr_map but skips the first "VME_OFFSET(curr_entry)"
                 * bytes of the submap.
                 * "curr_offset" always represents the offset of a virtual
                 * address in the curr_map relative to the absolute address
                 * space (i.e. the top-level VM map).
                 */
                curr_offset +=
                    (VME_OFFSET(curr_entry) - curr_entry->vme_start);
                curr_address = user_address + curr_offset;
                /* switch to the submap */
                curr_map = VME_SUBMAP(curr_entry);
                curr_depth++;
                curr_entry = NULL;
        }

// LP64todo: all the current tools are 32bit, obviously never worked for 64b
// so probably should be a real 32b ID vs. ptr.
// Current users just check for equality

        if (curr_entry == NULL) {
                /* no VM region contains the address... */

                if (do_region_footprint && /* we want footprint numbers */
                    next_entry == NULL && /* & there are no more regions */
                    /* & we haven't already provided our fake region: */
                    user_address <= vm_map_last_entry(map)->vme_end) {
                        ledger_amount_t ledger_resident, ledger_compressed;

                        /*
                         * Add a fake memory region to account for
                         * purgeable and/or ledger-tagged memory that
                         * counts towards this task's memory footprint,
                         * i.e. the resident/compressed pages of non-volatile
                         * objects owned by that task.
                         */
                        task_ledgers_footprint(map->pmap->ledger,
                            &ledger_resident,
                            &ledger_compressed);
                        if (ledger_resident + ledger_compressed == 0) {
                                /* no purgeable memory usage to report */
                                return KERN_INVALID_ADDRESS;
                        }
                        /* fake region to show nonvolatile footprint */
                        if (look_for_pages) {
                                submap_info->protection = VM_PROT_DEFAULT;
                                submap_info->max_protection = VM_PROT_DEFAULT;
                                submap_info->inheritance = VM_INHERIT_DEFAULT;
                                submap_info->offset = 0;
                                submap_info->user_tag = -1;
                                submap_info->pages_resident = (unsigned int) (ledger_resident / effective_page_size);
                                submap_info->pages_shared_now_private = 0;
                                submap_info->pages_swapped_out = (unsigned int) (ledger_compressed / effective_page_size);
                                submap_info->pages_dirtied = submap_info->pages_resident;
                                submap_info->ref_count = 1;
                                submap_info->shadow_depth = 0;
                                submap_info->external_pager = 0;
                                submap_info->share_mode = SM_PRIVATE;
                                submap_info->is_submap = 0;
                                submap_info->behavior = VM_BEHAVIOR_DEFAULT;
                                submap_info->object_id = VM_OBJECT_ID_FAKE(map, task_ledgers.purgeable_nonvolatile);
                                submap_info->user_wired_count = 0;
                                submap_info->pages_reusable = 0;
                        } else {
                                short_info->user_tag = -1;
                                short_info->offset = 0;
                                short_info->protection = VM_PROT_DEFAULT;
                                short_info->inheritance = VM_INHERIT_DEFAULT;
                                short_info->max_protection = VM_PROT_DEFAULT;
                                short_info->behavior = VM_BEHAVIOR_DEFAULT;
                                short_info->user_wired_count = 0;
                                short_info->is_submap = 0;
                                short_info->object_id = VM_OBJECT_ID_FAKE(map, task_ledgers.purgeable_nonvolatile);
                                short_info->external_pager = 0;
                                short_info->shadow_depth = 0;
                                short_info->share_mode = SM_PRIVATE;
                                short_info->ref_count = 1;
                        }
                        *nesting_depth = 0;
                        *size = (vm_map_size_t) (ledger_resident + ledger_compressed);
//                      *address = user_address;
                        *address = vm_map_last_entry(map)->vme_end;
                        return KERN_SUCCESS;
                }

                if (next_entry == NULL) {
                        /* ... and no VM region follows it either */
                        return KERN_INVALID_ADDRESS;
                }
                /* ... gather info about the next VM region */
                curr_entry = next_entry;
                curr_map = next_map;    /* still locked ... */
                curr_address = next_address;
                curr_skip = next_skip;
                curr_offset = next_offset;
                curr_depth = next_depth;
                curr_max_above = next_max_above;
                curr_max_below = next_max_below;
        } else {
                /* we won't need "next_entry" after all */
                if (next_entry != NULL) {
                        /* release "next_map" */
                        if (next_map != curr_map && not_in_kdp) {
                                vm_map_unlock_read(next_map);
                        }
                }
        }
        next_entry = NULL;
        next_map = NULL;
        next_offset = 0;
        next_skip = 0;
        next_depth = 0;
        next_max_below = -1;
        next_max_above = -1;

        if (curr_entry->is_sub_map &&
            curr_depth < user_max_depth) {
                /*
                 * We're not as deep as we could be:  we must have
                 * gone back up after not finding anything mapped
                 * below the original top-level map entry's.
                 * Let's move "curr_address" forward and recurse again.
                 */
                user_address = curr_address;
                goto recurse_again;
        }

        *nesting_depth = curr_depth;
        *size = curr_max_above + curr_max_below;
        *address = user_address + curr_skip - curr_max_below;

        if (look_for_pages) {
                submap_info->user_tag = VME_ALIAS(curr_entry);
                submap_info->offset = VME_OFFSET(curr_entry);
                submap_info->protection = curr_entry->protection;
                submap_info->inheritance = curr_entry->inheritance;
                submap_info->max_protection = curr_entry->max_protection;
                submap_info->behavior = curr_entry->behavior;
                submap_info->user_wired_count = curr_entry->user_wired_count;
                submap_info->is_submap = curr_entry->is_sub_map;
                submap_info->object_id = VM_OBJECT_ID(VME_OBJECT(curr_entry));
        } else {
                short_info->user_tag = VME_ALIAS(curr_entry);
                short_info->offset = VME_OFFSET(curr_entry);
                short_info->protection = curr_entry->protection;
                short_info->inheritance = curr_entry->inheritance;
                short_info->max_protection = curr_entry->max_protection;
                short_info->behavior = curr_entry->behavior;
                short_info->user_wired_count = curr_entry->user_wired_count;
                short_info->is_submap = curr_entry->is_sub_map;
                short_info->object_id = VM_OBJECT_ID(VME_OBJECT(curr_entry));
        }

        extended.pages_resident = 0;
        extended.pages_swapped_out = 0;
        extended.pages_shared_now_private = 0;
        extended.pages_dirtied = 0;
        extended.pages_reusable = 0;
        extended.external_pager = 0;
        extended.shadow_depth = 0;
        extended.share_mode = SM_EMPTY;
        extended.ref_count = 0;

        if (not_in_kdp) {
                if (!curr_entry->is_sub_map) {
                        vm_map_offset_t range_start, range_end;
                        range_start = MAX((curr_address - curr_max_below),
                            curr_entry->vme_start);
                        range_end = MIN((curr_address + curr_max_above),
                            curr_entry->vme_end);
                        vm_map_region_walk(curr_map,
                            range_start,
                            curr_entry,
                            (VME_OFFSET(curr_entry) +
                            (range_start -
                            curr_entry->vme_start)),
                            range_end - range_start,
                            &extended,
                            look_for_pages, VM_REGION_EXTENDED_INFO_COUNT);
                        if (extended.external_pager &&
                            extended.ref_count == 2 &&
                            extended.share_mode == SM_SHARED) {
                                extended.share_mode = SM_PRIVATE;
                        }
                } else {
                        if (curr_entry->use_pmap) {
                                extended.share_mode = SM_TRUESHARED;
                        } else {
                                extended.share_mode = SM_PRIVATE;
                        }
                        extended.ref_count = os_ref_get_count(&VME_SUBMAP(curr_entry)->map_refcnt);
                }
        }

        if (look_for_pages) {
                submap_info->pages_resident = extended.pages_resident;
                submap_info->pages_swapped_out = extended.pages_swapped_out;
                submap_info->pages_shared_now_private =
                    extended.pages_shared_now_private;
                submap_info->pages_dirtied = extended.pages_dirtied;
                submap_info->external_pager = extended.external_pager;
                submap_info->shadow_depth = extended.shadow_depth;
                submap_info->share_mode = extended.share_mode;
                submap_info->ref_count = extended.ref_count;

                if (original_count >= VM_REGION_SUBMAP_INFO_V1_COUNT_64) {
                        submap_info->pages_reusable = extended.pages_reusable;
                }
                if (original_count >= VM_REGION_SUBMAP_INFO_V2_COUNT_64) {
                        submap_info->object_id_full = (vm_object_id_t) (VME_OBJECT(curr_entry) != NULL) ? VM_KERNEL_ADDRPERM(VME_OBJECT(curr_entry)) : 0ULL;
                }
        } else {
                short_info->external_pager = extended.external_pager;
                short_info->shadow_depth = extended.shadow_depth;
                short_info->share_mode = extended.share_mode;
                short_info->ref_count = extended.ref_count;
        }

        if (not_in_kdp) {
                vm_map_unlock_read(curr_map);
        }

        return KERN_SUCCESS;
}

/*
 *      vm_region:
 *
 *      User call to obtain information about a region in
 *      a task's address map. Currently, only one flavor is
 *      supported.
 *
 *      XXX The reserved and behavior fields cannot be filled
 *          in until the vm merge from the IK is completed, and
 *          vm_reserve is implemented.
 */

kern_return_t
vm_map_region(
        vm_map_t                 map,
        vm_map_offset_t *address,               /* IN/OUT */
        vm_map_size_t           *size,                  /* OUT */
        vm_region_flavor_t       flavor,                /* IN */
        vm_region_info_t         info,                  /* OUT */
        mach_msg_type_number_t  *count, /* IN/OUT */
        mach_port_t             *object_name)           /* OUT */
{
        vm_map_entry_t          tmp_entry;
        vm_map_entry_t          entry;
        vm_map_offset_t         start;

        if (map == VM_MAP_NULL) {
                return KERN_INVALID_ARGUMENT;
        }

        switch (flavor) {
        case VM_REGION_BASIC_INFO:
                /* legacy for old 32-bit objects info */
        {
                vm_region_basic_info_t  basic;

                if (*count < VM_REGION_BASIC_INFO_COUNT) {
                        return KERN_INVALID_ARGUMENT;
                }

                basic = (vm_region_basic_info_t) info;
                *count = VM_REGION_BASIC_INFO_COUNT;

                vm_map_lock_read(map);

                start = *address;
                if (!vm_map_lookup_entry(map, start, &tmp_entry)) {
                        if ((entry = tmp_entry->vme_next) == vm_map_to_entry(map)) {
                                vm_map_unlock_read(map);
                                return KERN_INVALID_ADDRESS;
                        }
                } else {
                        entry = tmp_entry;
                }

                start = entry->vme_start;

                basic->offset = (uint32_t)VME_OFFSET(entry);
                basic->protection = entry->protection;
                basic->inheritance = entry->inheritance;
                basic->max_protection = entry->max_protection;
                basic->behavior = entry->behavior;
                basic->user_wired_count = entry->user_wired_count;
                basic->reserved = entry->is_sub_map;
                *address = start;
                *size = (entry->vme_end - start);

                if (object_name) {
                        *object_name = IP_NULL;
                }
                if (entry->is_sub_map) {
                        basic->shared = FALSE;
                } else {
                        basic->shared = entry->is_shared;
                }

                vm_map_unlock_read(map);
                return KERN_SUCCESS;
        }

        case VM_REGION_BASIC_INFO_64:
        {
                vm_region_basic_info_64_t       basic;

                if (*count < VM_REGION_BASIC_INFO_COUNT_64) {
                        return KERN_INVALID_ARGUMENT;
                }

                basic = (vm_region_basic_info_64_t) info;
                *count = VM_REGION_BASIC_INFO_COUNT_64;

                vm_map_lock_read(map);

                start = *address;
                if (!vm_map_lookup_entry(map, start, &tmp_entry)) {
                        if ((entry = tmp_entry->vme_next) == vm_map_to_entry(map)) {
                                vm_map_unlock_read(map);
                                return KERN_INVALID_ADDRESS;
                        }
                } else {
                        entry = tmp_entry;
                }

                start = entry->vme_start;

                basic->offset = VME_OFFSET(entry);
                basic->protection = entry->protection;
                basic->inheritance = entry->inheritance;
                basic->max_protection = entry->max_protection;
                basic->behavior = entry->behavior;
                basic->user_wired_count = entry->user_wired_count;
                basic->reserved = entry->is_sub_map;
                *address = start;
                *size = (entry->vme_end - start);

                if (object_name) {
                        *object_name = IP_NULL;
                }
                if (entry->is_sub_map) {
                        basic->shared = FALSE;
                } else {
                        basic->shared = entry->is_shared;
                }

                vm_map_unlock_read(map);
                return KERN_SUCCESS;
        }
        case VM_REGION_EXTENDED_INFO:
                if (*count < VM_REGION_EXTENDED_INFO_COUNT) {
                        return KERN_INVALID_ARGUMENT;
                }
                OS_FALLTHROUGH;
        case VM_REGION_EXTENDED_INFO__legacy:
                if (*count < VM_REGION_EXTENDED_INFO_COUNT__legacy) {
                        return KERN_INVALID_ARGUMENT;
                }

                {
                        vm_region_extended_info_t       extended;
                        mach_msg_type_number_t original_count;
                        int effective_page_size, effective_page_shift;

                        extended = (vm_region_extended_info_t) info;

                        effective_page_shift = vm_self_region_page_shift(map);
                        effective_page_size = (1 << effective_page_shift);

                        vm_map_lock_read(map);

                        start = *address;
                        if (!vm_map_lookup_entry(map, start, &tmp_entry)) {
                                if ((entry = tmp_entry->vme_next) == vm_map_to_entry(map)) {
                                        vm_map_unlock_read(map);
                                        return KERN_INVALID_ADDRESS;
                                }
                        } else {
                                entry = tmp_entry;
                        }
                        start = entry->vme_start;

                        extended->protection = entry->protection;
                        extended->user_tag = VME_ALIAS(entry);
                        extended->pages_resident = 0;
                        extended->pages_swapped_out = 0;
                        extended->pages_shared_now_private = 0;
                        extended->pages_dirtied = 0;
                        extended->external_pager = 0;
                        extended->shadow_depth = 0;

                        original_count = *count;
                        if (flavor == VM_REGION_EXTENDED_INFO__legacy) {
                                *count = VM_REGION_EXTENDED_INFO_COUNT__legacy;
                        } else {
                                extended->pages_reusable = 0;
                                *count = VM_REGION_EXTENDED_INFO_COUNT;
                        }

                        vm_map_region_walk(map, start, entry, VME_OFFSET(entry), entry->vme_end - start, extended, TRUE, *count);

                        if (extended->external_pager && extended->ref_count == 2 && extended->share_mode == SM_SHARED) {
                                extended->share_mode = SM_PRIVATE;
                        }

                        if (object_name) {
                                *object_name = IP_NULL;
                        }
                        *address = start;
                        *size = (entry->vme_end - start);

                        vm_map_unlock_read(map);
                        return KERN_SUCCESS;
                }
        case VM_REGION_TOP_INFO:
        {
                vm_region_top_info_t    top;

                if (*count < VM_REGION_TOP_INFO_COUNT) {
                        return KERN_INVALID_ARGUMENT;
                }

                top = (vm_region_top_info_t) info;
                *count = VM_REGION_TOP_INFO_COUNT;

                vm_map_lock_read(map);

                start = *address;
                if (!vm_map_lookup_entry(map, start, &tmp_entry)) {
                        if ((entry = tmp_entry->vme_next) == vm_map_to_entry(map)) {
                                vm_map_unlock_read(map);
                                return KERN_INVALID_ADDRESS;
                        }
                } else {
                        entry = tmp_entry;
                }
                start = entry->vme_start;

                top->private_pages_resident = 0;
                top->shared_pages_resident = 0;

                vm_map_region_top_walk(entry, top);

                if (object_name) {
                        *object_name = IP_NULL;
                }
                *address = start;
                *size = (entry->vme_end - start);

                vm_map_unlock_read(map);
                return KERN_SUCCESS;
        }
        default:
                return KERN_INVALID_ARGUMENT;
        }
}

#define OBJ_RESIDENT_COUNT(obj, entry_size)                             \
        MIN((entry_size),                                               \
            ((obj)->all_reusable ?                                      \
             (obj)->wired_page_count :                                  \
             (obj)->resident_page_count - (obj)->reusable_page_count))

void
vm_map_region_top_walk(
        vm_map_entry_t             entry,
        vm_region_top_info_t       top)
{
        if (VME_OBJECT(entry) == 0 || entry->is_sub_map) {
                top->share_mode = SM_EMPTY;
                top->ref_count = 0;
                top->obj_id = 0;
                return;
        }

        {
                struct  vm_object *obj, *tmp_obj;
                int             ref_count;
                uint32_t        entry_size;

                entry_size = (uint32_t) ((entry->vme_end - entry->vme_start) / PAGE_SIZE_64);

                obj = VME_OBJECT(entry);

                vm_object_lock(obj);

                if ((ref_count = obj->ref_count) > 1 && obj->paging_in_progress) {
                        ref_count--;
                }

                assert(obj->reusable_page_count <= obj->resident_page_count);
                if (obj->shadow) {
                        if (ref_count == 1) {
                                top->private_pages_resident =
                                    OBJ_RESIDENT_COUNT(obj, entry_size);
                        } else {
                                top->shared_pages_resident =
                                    OBJ_RESIDENT_COUNT(obj, entry_size);
                        }
                        top->ref_count  = ref_count;
                        top->share_mode = SM_COW;

                        while ((tmp_obj = obj->shadow)) {
                                vm_object_lock(tmp_obj);
                                vm_object_unlock(obj);
                                obj = tmp_obj;

                                if ((ref_count = obj->ref_count) > 1 && obj->paging_in_progress) {
                                        ref_count--;
                                }

                                assert(obj->reusable_page_count <= obj->resident_page_count);
                                top->shared_pages_resident +=
                                    OBJ_RESIDENT_COUNT(obj, entry_size);
                                top->ref_count += ref_count - 1;
                        }
                } else {
                        if (entry->superpage_size) {
                                top->share_mode = SM_LARGE_PAGE;
                                top->shared_pages_resident = 0;
                                top->private_pages_resident = entry_size;
                        } else if (entry->needs_copy) {
                                top->share_mode = SM_COW;
                                top->shared_pages_resident =
                                    OBJ_RESIDENT_COUNT(obj, entry_size);
                        } else {
                                if (ref_count == 1 ||
                                    (ref_count == 2 && obj->named)) {
                                        top->share_mode = SM_PRIVATE;
                                        top->private_pages_resident =
                                            OBJ_RESIDENT_COUNT(obj,
                                            entry_size);
                                } else {
                                        top->share_mode = SM_SHARED;
                                        top->shared_pages_resident =
                                            OBJ_RESIDENT_COUNT(obj,
                                            entry_size);
                                }
                        }
                        top->ref_count = ref_count;
                }
                /* XXX K64: obj_id will be truncated */
                top->obj_id = (unsigned int) (uintptr_t)VM_KERNEL_ADDRPERM(obj);

                vm_object_unlock(obj);
        }
}

void
vm_map_region_walk(
        vm_map_t                        map,
        vm_map_offset_t                 va,
        vm_map_entry_t                  entry,
        vm_object_offset_t              offset,
        vm_object_size_t                range,
        vm_region_extended_info_t       extended,
        boolean_t                       look_for_pages,
        mach_msg_type_number_t count)
{
        struct vm_object *obj, *tmp_obj;
        vm_map_offset_t       last_offset;
        int               i;
        int               ref_count;
        struct vm_object        *shadow_object;
        unsigned short          shadow_depth;
        boolean_t         do_region_footprint;
        int                     effective_page_size, effective_page_shift;
        vm_map_offset_t         effective_page_mask;

        do_region_footprint = task_self_region_footprint();

        if ((VME_OBJECT(entry) == 0) ||
            (entry->is_sub_map) ||
            (VME_OBJECT(entry)->phys_contiguous &&
            !entry->superpage_size)) {
                extended->share_mode = SM_EMPTY;
                extended->ref_count = 0;
                return;
        }

        if (entry->superpage_size) {
                extended->shadow_depth = 0;
                extended->share_mode = SM_LARGE_PAGE;
                extended->ref_count = 1;
                extended->external_pager = 0;

                /* TODO4K: Superpage in 4k mode? */
                extended->pages_resident = (unsigned int)(range >> PAGE_SHIFT);
                extended->shadow_depth = 0;
                return;
        }

        effective_page_shift = vm_self_region_page_shift(map);
        effective_page_size = (1 << effective_page_shift);
        effective_page_mask = effective_page_size - 1;

        offset = vm_map_trunc_page(offset, effective_page_mask);

        obj = VME_OBJECT(entry);

        vm_object_lock(obj);

        if ((ref_count = obj->ref_count) > 1 && obj->paging_in_progress) {
                ref_count--;
        }

        if (look_for_pages) {
                for (last_offset = offset + range;
                    offset < last_offset;
                    offset += effective_page_size, va += effective_page_size) {
                        if (do_region_footprint) {
                                int disp;

                                disp = 0;
                                if (map->has_corpse_footprint) {
                                        /*
                                         * Query the page info data we saved
                                         * while forking the corpse.
                                         */
                                        vm_map_corpse_footprint_query_page_info(
                                                map,
                                                va,
                                                &disp);
                                } else {
                                        /*
                                         * Query the pmap.
                                         */
                                        vm_map_footprint_query_page_info(
                                                map,
                                                entry,
                                                va,
                                                &disp);
                                }
                                if (disp & VM_PAGE_QUERY_PAGE_PRESENT) {
                                        extended->pages_resident++;
                                }
                                if (disp & VM_PAGE_QUERY_PAGE_REUSABLE) {
                                        extended->pages_reusable++;
                                }
                                if (disp & VM_PAGE_QUERY_PAGE_DIRTY) {
                                        extended->pages_dirtied++;
                                }
                                if (disp & PMAP_QUERY_PAGE_COMPRESSED) {
                                        extended->pages_swapped_out++;
                                }
                                continue;
                        }

                        vm_map_region_look_for_page(map, va, obj,
                            vm_object_trunc_page(offset), ref_count,
                            0, extended, count);
                }

                if (do_region_footprint) {
                        goto collect_object_info;
                }
        } else {
collect_object_info:
                shadow_object = obj->shadow;
                shadow_depth = 0;

                if (!(obj->internal)) {
                        extended->external_pager = 1;
                }

                if (shadow_object != VM_OBJECT_NULL) {
                        vm_object_lock(shadow_object);
                        for (;
                            shadow_object != VM_OBJECT_NULL;
                            shadow_depth++) {
                                vm_object_t     next_shadow;

                                if (!(shadow_object->internal)) {
                                        extended->external_pager = 1;
                                }

                                next_shadow = shadow_object->shadow;
                                if (next_shadow) {
                                        vm_object_lock(next_shadow);
                                }
                                vm_object_unlock(shadow_object);
                                shadow_object = next_shadow;
                        }
                }
                extended->shadow_depth = shadow_depth;
        }

        if (extended->shadow_depth || entry->needs_copy) {
                extended->share_mode = SM_COW;
        } else {
                if (ref_count == 1) {
                        extended->share_mode = SM_PRIVATE;
                } else {
                        if (obj->true_share) {
                                extended->share_mode = SM_TRUESHARED;
                        } else {
                                extended->share_mode = SM_SHARED;
                        }
                }
        }
        extended->ref_count = ref_count - extended->shadow_depth;

        for (i = 0; i < extended->shadow_depth; i++) {
                if ((tmp_obj = obj->shadow) == 0) {
                        break;
                }
                vm_object_lock(tmp_obj);
                vm_object_unlock(obj);

                if ((ref_count = tmp_obj->ref_count) > 1 && tmp_obj->paging_in_progress) {
                        ref_count--;
                }

                extended->ref_count += ref_count;
                obj = tmp_obj;
        }
        vm_object_unlock(obj);

        if (extended->share_mode == SM_SHARED) {
                vm_map_entry_t       cur;
                vm_map_entry_t       last;
                int      my_refs;

                obj = VME_OBJECT(entry);
                last = vm_map_to_entry(map);
                my_refs = 0;

                if ((ref_count = obj->ref_count) > 1 && obj->paging_in_progress) {
                        ref_count--;
                }
                for (cur = vm_map_first_entry(map); cur != last; cur = cur->vme_next) {
                        my_refs += vm_map_region_count_obj_refs(cur, obj);
                }

                if (my_refs == ref_count) {
                        extended->share_mode = SM_PRIVATE_ALIASED;
                } else if (my_refs > 1) {
                        extended->share_mode = SM_SHARED_ALIASED;
                }
        }
}


/* object is locked on entry and locked on return */


static void
vm_map_region_look_for_page(
        __unused vm_map_t               map,
        __unused vm_map_offset_t        va,
        vm_object_t                     object,
        vm_object_offset_t              offset,
        int                             max_refcnt,
        unsigned short                  depth,
        vm_region_extended_info_t       extended,
        mach_msg_type_number_t count)
{
        vm_page_t       p;
        vm_object_t     shadow;
        int             ref_count;
        vm_object_t     caller_object;

        shadow = object->shadow;
        caller_object = object;


        while (TRUE) {
                if (!(object->internal)) {
                        extended->external_pager = 1;
                }

                if ((p = vm_page_lookup(object, offset)) != VM_PAGE_NULL) {
                        if (shadow && (max_refcnt == 1)) {
                                extended->pages_shared_now_private++;
                        }

                        if (!p->vmp_fictitious &&
                            (p->vmp_dirty || pmap_is_modified(VM_PAGE_GET_PHYS_PAGE(p)))) {
                                extended->pages_dirtied++;
                        } else if (count >= VM_REGION_EXTENDED_INFO_COUNT) {
                                if (p->vmp_reusable || object->all_reusable) {
                                        extended->pages_reusable++;
                                }
                        }

                        extended->pages_resident++;

                        if (object != caller_object) {
                                vm_object_unlock(object);
                        }

                        return;
                }
                if (object->internal &&
                    object->alive &&
                    !object->terminating &&
                    object->pager_ready) {
                        if (VM_COMPRESSOR_PAGER_STATE_GET(object, offset)
                            == VM_EXTERNAL_STATE_EXISTS) {
                                /* the pager has that page */
                                extended->pages_swapped_out++;
                                if (object != caller_object) {
                                        vm_object_unlock(object);
                                }
                                return;
                        }
                }

                if (shadow) {
                        vm_object_lock(shadow);

                        if ((ref_count = shadow->ref_count) > 1 && shadow->paging_in_progress) {
                                ref_count--;
                        }

                        if (++depth > extended->shadow_depth) {
                                extended->shadow_depth = depth;
                        }

                        if (ref_count > max_refcnt) {
                                max_refcnt = ref_count;
                        }

                        if (object != caller_object) {
                                vm_object_unlock(object);
                        }

                        offset = offset + object->vo_shadow_offset;
                        object = shadow;
                        shadow = object->shadow;
                        continue;
                }
                if (object != caller_object) {
                        vm_object_unlock(object);
                }
                break;
        }
}

static int
vm_map_region_count_obj_refs(
        vm_map_entry_t    entry,
        vm_object_t       object)
{
        int ref_count;
        vm_object_t chk_obj;
        vm_object_t tmp_obj;

        if (VME_OBJECT(entry) == 0) {
                return 0;
        }

        if (entry->is_sub_map) {
                return 0;
        } else {
                ref_count = 0;

                chk_obj = VME_OBJECT(entry);
                vm_object_lock(chk_obj);

                while (chk_obj) {
                        if (chk_obj == object) {
                                ref_count++;
                        }
                        tmp_obj = chk_obj->shadow;
                        if (tmp_obj) {
                                vm_object_lock(tmp_obj);
                        }
                        vm_object_unlock(chk_obj);

                        chk_obj = tmp_obj;
                }
        }
        return ref_count;
}


/*
 *      Routine:        vm_map_simplify
 *
 *      Description:
 *              Attempt to simplify the map representation in
 *              the vicinity of the given starting address.
 *      Note:
 *              This routine is intended primarily to keep the
 *              kernel maps more compact -- they generally don't
 *              benefit from the "expand a map entry" technology
 *              at allocation time because the adjacent entry
 *              is often wired down.
 */
void
vm_map_simplify_entry(
        vm_map_t        map,
        vm_map_entry_t  this_entry)
{
        vm_map_entry_t  prev_entry;

        counter(c_vm_map_simplify_entry_called++);

        prev_entry = this_entry->vme_prev;

        if ((this_entry != vm_map_to_entry(map)) &&
            (prev_entry != vm_map_to_entry(map)) &&

            (prev_entry->vme_end == this_entry->vme_start) &&

            (prev_entry->is_sub_map == this_entry->is_sub_map) &&
            (VME_OBJECT(prev_entry) == VME_OBJECT(this_entry)) &&
            ((VME_OFFSET(prev_entry) + (prev_entry->vme_end -
            prev_entry->vme_start))
            == VME_OFFSET(this_entry)) &&

            (prev_entry->behavior == this_entry->behavior) &&
            (prev_entry->needs_copy == this_entry->needs_copy) &&
            (prev_entry->protection == this_entry->protection) &&
            (prev_entry->max_protection == this_entry->max_protection) &&
            (prev_entry->inheritance == this_entry->inheritance) &&
            (prev_entry->use_pmap == this_entry->use_pmap) &&
            (VME_ALIAS(prev_entry) == VME_ALIAS(this_entry)) &&
            (prev_entry->no_cache == this_entry->no_cache) &&
            (prev_entry->permanent == this_entry->permanent) &&
            (prev_entry->map_aligned == this_entry->map_aligned) &&
            (prev_entry->zero_wired_pages == this_entry->zero_wired_pages) &&
            (prev_entry->used_for_jit == this_entry->used_for_jit) &&
            (prev_entry->pmap_cs_associated == this_entry->pmap_cs_associated) &&
            /* from_reserved_zone: OK if that field doesn't match */
            (prev_entry->iokit_acct == this_entry->iokit_acct) &&
            (prev_entry->vme_resilient_codesign ==
            this_entry->vme_resilient_codesign) &&
            (prev_entry->vme_resilient_media ==
            this_entry->vme_resilient_media) &&
            (prev_entry->vme_no_copy_on_read == this_entry->vme_no_copy_on_read) &&

            (prev_entry->wired_count == this_entry->wired_count) &&
            (prev_entry->user_wired_count == this_entry->user_wired_count) &&

            ((prev_entry->vme_atomic == FALSE) && (this_entry->vme_atomic == FALSE)) &&
            (prev_entry->in_transition == FALSE) &&
            (this_entry->in_transition == FALSE) &&
            (prev_entry->needs_wakeup == FALSE) &&
            (this_entry->needs_wakeup == FALSE) &&
            (prev_entry->is_shared == this_entry->is_shared) &&
            (prev_entry->superpage_size == FALSE) &&
            (this_entry->superpage_size == FALSE)
            ) {
                vm_map_store_entry_unlink(map, prev_entry);
                assert(prev_entry->vme_start < this_entry->vme_end);
                if (prev_entry->map_aligned) {
                        assert(VM_MAP_PAGE_ALIGNED(prev_entry->vme_start,
                            VM_MAP_PAGE_MASK(map)));
                }
                this_entry->vme_start = prev_entry->vme_start;
                VME_OFFSET_SET(this_entry, VME_OFFSET(prev_entry));

                if (map->holelistenabled) {
                        vm_map_store_update_first_free(map, this_entry, TRUE);
                }

                if (prev_entry->is_sub_map) {
                        vm_map_deallocate(VME_SUBMAP(prev_entry));
                } else {
                        vm_object_deallocate(VME_OBJECT(prev_entry));
                }
                vm_map_entry_dispose(map, prev_entry);
                SAVE_HINT_MAP_WRITE(map, this_entry);
                counter(c_vm_map_simplified++);
        }
}

void
vm_map_simplify(
        vm_map_t        map,
        vm_map_offset_t start)
{
        vm_map_entry_t  this_entry;

        vm_map_lock(map);
        if (vm_map_lookup_entry(map, start, &this_entry)) {
                vm_map_simplify_entry(map, this_entry);
                vm_map_simplify_entry(map, this_entry->vme_next);
        }
        counter(c_vm_map_simplify_called++);
        vm_map_unlock(map);
}

static void
vm_map_simplify_range(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end)
{
        vm_map_entry_t  entry;

        /*
         * The map should be locked (for "write") by the caller.
         */

        if (start >= end) {
                /* invalid address range */
                return;
        }

        start = vm_map_trunc_page(start,
            VM_MAP_PAGE_MASK(map));
        end = vm_map_round_page(end,
            VM_MAP_PAGE_MASK(map));

        if (!vm_map_lookup_entry(map, start, &entry)) {
                /* "start" is not mapped and "entry" ends before "start" */
                if (entry == vm_map_to_entry(map)) {
                        /* start with first entry in the map */
                        entry = vm_map_first_entry(map);
                } else {
                        /* start with next entry */
                        entry = entry->vme_next;
                }
        }

        while (entry != vm_map_to_entry(map) &&
            entry->vme_start <= end) {
                /* try and coalesce "entry" with its previous entry */
                vm_map_simplify_entry(map, entry);
                entry = entry->vme_next;
        }
}


/*
 *      Routine:        vm_map_machine_attribute
 *      Purpose:
 *              Provide machine-specific attributes to mappings,
 *              such as cachability etc. for machines that provide
 *              them.  NUMA architectures and machines with big/strange
 *              caches will use this.
 *      Note:
 *              Responsibilities for locking and checking are handled here,
 *              everything else in the pmap module. If any non-volatile
 *              information must be kept, the pmap module should handle
 *              it itself. [This assumes that attributes do not
 *              need to be inherited, which seems ok to me]
 */
kern_return_t
vm_map_machine_attribute(
        vm_map_t                        map,
        vm_map_offset_t         start,
        vm_map_offset_t         end,
        vm_machine_attribute_t  attribute,
        vm_machine_attribute_val_t* value)              /* IN/OUT */
{
        kern_return_t   ret;
        vm_map_size_t sync_size;
        vm_map_entry_t entry;

        if (start < vm_map_min(map) || end > vm_map_max(map)) {
                return KERN_INVALID_ADDRESS;
        }

        /* Figure how much memory we need to flush (in page increments) */
        sync_size = end - start;

        vm_map_lock(map);

        if (attribute != MATTR_CACHE) {
                /* If we don't have to find physical addresses, we */
                /* don't have to do an explicit traversal here.    */
                ret = pmap_attribute(map->pmap, start, end - start,
                    attribute, value);
                vm_map_unlock(map);
                return ret;
        }

        ret = KERN_SUCCESS;                                                                             /* Assume it all worked */

        while (sync_size) {
                if (vm_map_lookup_entry(map, start, &entry)) {
                        vm_map_size_t   sub_size;
                        if ((entry->vme_end - start) > sync_size) {
                                sub_size = sync_size;
                                sync_size = 0;
                        } else {
                                sub_size = entry->vme_end - start;
                                sync_size -= sub_size;
                        }
                        if (entry->is_sub_map) {
                                vm_map_offset_t sub_start;
                                vm_map_offset_t sub_end;

                                sub_start = (start - entry->vme_start)
                                    + VME_OFFSET(entry);
                                sub_end = sub_start + sub_size;
                                vm_map_machine_attribute(
                                        VME_SUBMAP(entry),
                                        sub_start,
                                        sub_end,
                                        attribute, value);
                        } else {
                                if (VME_OBJECT(entry)) {
                                        vm_page_t               m;
                                        vm_object_t             object;
                                        vm_object_t             base_object;
                                        vm_object_t             last_object;
                                        vm_object_offset_t      offset;
                                        vm_object_offset_t      base_offset;
                                        vm_map_size_t           range;
                                        range = sub_size;
                                        offset = (start - entry->vme_start)
                                            + VME_OFFSET(entry);
                                        offset = vm_object_trunc_page(offset);
                                        base_offset = offset;
                                        object = VME_OBJECT(entry);
                                        base_object = object;
                                        last_object = NULL;

                                        vm_object_lock(object);

                                        while (range) {
                                                m = vm_page_lookup(
                                                        object, offset);

                                                if (m && !m->vmp_fictitious) {
                                                        ret =
                                                            pmap_attribute_cache_sync(
                                                                VM_PAGE_GET_PHYS_PAGE(m),
                                                                PAGE_SIZE,
                                                                attribute, value);
                                                } else if (object->shadow) {
                                                        offset = offset + object->vo_shadow_offset;
                                                        last_object = object;
                                                        object = object->shadow;
                                                        vm_object_lock(last_object->shadow);
                                                        vm_object_unlock(last_object);
                                                        continue;
                                                }
                                                if (range < PAGE_SIZE) {
                                                        range = 0;
                                                } else {
                                                        range -= PAGE_SIZE;
                                                }

                                                if (base_object != object) {
                                                        vm_object_unlock(object);
                                                        vm_object_lock(base_object);
                                                        object = base_object;
                                                }
                                                /* Bump to the next page */
                                                base_offset += PAGE_SIZE;
                                                offset = base_offset;
                                        }
                                        vm_object_unlock(object);
                                }
                        }
                        start += sub_size;
                } else {
                        vm_map_unlock(map);
                        return KERN_FAILURE;
                }
        }

        vm_map_unlock(map);

        return ret;
}

/*
 *      vm_map_behavior_set:
 *
 *      Sets the paging reference behavior of the specified address
 *      range in the target map.  Paging reference behavior affects
 *      how pagein operations resulting from faults on the map will be
 *      clustered.
 */
kern_return_t
vm_map_behavior_set(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end,
        vm_behavior_t   new_behavior)
{
        vm_map_entry_t  entry;
        vm_map_entry_t  temp_entry;

        if (start > end ||
            start < vm_map_min(map) ||
            end > vm_map_max(map)) {
                return KERN_NO_SPACE;
        }

        switch (new_behavior) {
        /*
         * This first block of behaviors all set a persistent state on the specified
         * memory range.  All we have to do here is to record the desired behavior
         * in the vm_map_entry_t's.
         */

        case VM_BEHAVIOR_DEFAULT:
        case VM_BEHAVIOR_RANDOM:
        case VM_BEHAVIOR_SEQUENTIAL:
        case VM_BEHAVIOR_RSEQNTL:
        case VM_BEHAVIOR_ZERO_WIRED_PAGES:
                vm_map_lock(map);

                /*
                 *      The entire address range must be valid for the map.
                 *      Note that vm_map_range_check() does a
                 *      vm_map_lookup_entry() internally and returns the
                 *      entry containing the start of the address range if
                 *      the entire range is valid.
                 */
                if (vm_map_range_check(map, start, end, &temp_entry)) {
                        entry = temp_entry;
                        vm_map_clip_start(map, entry, start);
                } else {
                        vm_map_unlock(map);
                        return KERN_INVALID_ADDRESS;
                }

                while ((entry != vm_map_to_entry(map)) && (entry->vme_start < end)) {
                        vm_map_clip_end(map, entry, end);
                        if (entry->is_sub_map) {
                                assert(!entry->use_pmap);
                        }

                        if (new_behavior == VM_BEHAVIOR_ZERO_WIRED_PAGES) {
                                entry->zero_wired_pages = TRUE;
                        } else {
                                entry->behavior = new_behavior;
                        }
                        entry = entry->vme_next;
                }

                vm_map_unlock(map);
                break;

        /*
         * The rest of these are different from the above in that they cause
         * an immediate action to take place as opposed to setting a behavior that
         * affects future actions.
         */

        case VM_BEHAVIOR_WILLNEED:
                return vm_map_willneed(map, start, end);

        case VM_BEHAVIOR_DONTNEED:
                return vm_map_msync(map, start, end - start, VM_SYNC_DEACTIVATE | VM_SYNC_CONTIGUOUS);

        case VM_BEHAVIOR_FREE:
                return vm_map_msync(map, start, end - start, VM_SYNC_KILLPAGES | VM_SYNC_CONTIGUOUS);

        case VM_BEHAVIOR_REUSABLE:
                return vm_map_reusable_pages(map, start, end);

        case VM_BEHAVIOR_REUSE:
                return vm_map_reuse_pages(map, start, end);

        case VM_BEHAVIOR_CAN_REUSE:
                return vm_map_can_reuse(map, start, end);

#if MACH_ASSERT
        case VM_BEHAVIOR_PAGEOUT:
                return vm_map_pageout(map, start, end);
#endif /* MACH_ASSERT */

        default:
                return KERN_INVALID_ARGUMENT;
        }

        return KERN_SUCCESS;
}


/*
 * Internals for madvise(MADV_WILLNEED) system call.
 *
 * The implementation is to do:-
 * a) read-ahead if the mapping corresponds to a mapped regular file
 * b) or, fault in the pages (zero-fill, decompress etc) if it's an anonymous mapping
 */


static kern_return_t
vm_map_willneed(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end
        )
{
        vm_map_entry_t                  entry;
        vm_object_t                     object;
        memory_object_t                 pager;
        struct vm_object_fault_info     fault_info = {};
        kern_return_t                   kr;
        vm_object_size_t                len;
        vm_object_offset_t              offset;

        fault_info.interruptible = THREAD_UNINT;        /* ignored value */
        fault_info.behavior      = VM_BEHAVIOR_SEQUENTIAL;
        fault_info.stealth       = TRUE;

        /*
         * The MADV_WILLNEED operation doesn't require any changes to the
         * vm_map_entry_t's, so the read lock is sufficient.
         */

        vm_map_lock_read(map);

        /*
         * The madvise semantics require that the address range be fully
         * allocated with no holes.  Otherwise, we're required to return
         * an error.
         */

        if (!vm_map_range_check(map, start, end, &entry)) {
                vm_map_unlock_read(map);
                return KERN_INVALID_ADDRESS;
        }

        /*
         * Examine each vm_map_entry_t in the range.
         */
        for (; entry != vm_map_to_entry(map) && start < end;) {
                /*
                 * The first time through, the start address could be anywhere
                 * within the vm_map_entry we found.  So adjust the offset to
                 * correspond.  After that, the offset will always be zero to
                 * correspond to the beginning of the current vm_map_entry.
                 */
                offset = (start - entry->vme_start) + VME_OFFSET(entry);

                /*
                 * Set the length so we don't go beyond the end of the
                 * map_entry or beyond the end of the range we were given.
                 * This range could span also multiple map entries all of which
                 * map different files, so make sure we only do the right amount
                 * of I/O for each object.  Note that it's possible for there
                 * to be multiple map entries all referring to the same object
                 * but with different page permissions, but it's not worth
                 * trying to optimize that case.
                 */
                len = MIN(entry->vme_end - start, end - start);

                if ((vm_size_t) len != len) {
                        /* 32-bit overflow */
                        len = (vm_size_t) (0 - PAGE_SIZE);
                }
                fault_info.cluster_size = (vm_size_t) len;
                fault_info.lo_offset    = offset;
                fault_info.hi_offset    = offset + len;
                fault_info.user_tag     = VME_ALIAS(entry);
                fault_info.pmap_options = 0;
                if (entry->iokit_acct ||
                    (!entry->is_sub_map && !entry->use_pmap)) {
                        fault_info.pmap_options |= PMAP_OPTIONS_ALT_ACCT;
                }

                /*
                 * If the entry is a submap OR there's no read permission
                 * to this mapping, then just skip it.
                 */
                if ((entry->is_sub_map) || (entry->protection & VM_PROT_READ) == 0) {
                        entry = entry->vme_next;
                        start = entry->vme_start;
                        continue;
                }

                object = VME_OBJECT(entry);

                if (object == NULL ||
                    (object && object->internal)) {
                        /*
                         * Memory range backed by anonymous memory.
                         */
                        vm_size_t region_size = 0, effective_page_size = 0;
                        vm_map_offset_t addr = 0, effective_page_mask = 0;

                        region_size = len;
                        addr = start;

                        effective_page_mask = MIN(vm_map_page_mask(current_map()), PAGE_MASK);
                        effective_page_size = effective_page_mask + 1;

                        vm_map_unlock_read(map);

                        while (region_size) {
                                vm_pre_fault(
                                        vm_map_trunc_page(addr, effective_page_mask),
                                        VM_PROT_READ | VM_PROT_WRITE);

                                region_size -= effective_page_size;
                                addr += effective_page_size;
                        }
                } else {
                        /*
                         * Find the file object backing this map entry.  If there is
                         * none, then we simply ignore the "will need" advice for this
                         * entry and go on to the next one.
                         */
                        if ((object = find_vnode_object(entry)) == VM_OBJECT_NULL) {
                                entry = entry->vme_next;
                                start = entry->vme_start;
                                continue;
                        }

                        vm_object_paging_begin(object);
                        pager = object->pager;
                        vm_object_unlock(object);

                        /*
                         * The data_request() could take a long time, so let's
                         * release the map lock to avoid blocking other threads.
                         */
                        vm_map_unlock_read(map);

                        /*
                         * Get the data from the object asynchronously.
                         *
                         * Note that memory_object_data_request() places limits on the
                         * amount of I/O it will do.  Regardless of the len we
                         * specified, it won't do more than MAX_UPL_TRANSFER_BYTES and it
                         * silently truncates the len to that size.  This isn't
                         * necessarily bad since madvise shouldn't really be used to
                         * page in unlimited amounts of data.  Other Unix variants
                         * limit the willneed case as well.  If this turns out to be an
                         * issue for developers, then we can always adjust the policy
                         * here and still be backwards compatible since this is all
                         * just "advice".
                         */
                        kr = memory_object_data_request(
                                pager,
                                vm_object_trunc_page(offset) + object->paging_offset,
                                0,      /* ignored */
                                VM_PROT_READ,
                                (memory_object_fault_info_t)&fault_info);

                        vm_object_lock(object);
                        vm_object_paging_end(object);
                        vm_object_unlock(object);

                        /*
                         * If we couldn't do the I/O for some reason, just give up on
                         * the madvise.  We still return success to the user since
                         * madvise isn't supposed to fail when the advice can't be
                         * taken.
                         */

                        if (kr != KERN_SUCCESS) {
                                return KERN_SUCCESS;
                        }
                }

                start += len;
                if (start >= end) {
                        /* done */
                        return KERN_SUCCESS;
                }

                /* look up next entry */
                vm_map_lock_read(map);
                if (!vm_map_lookup_entry(map, start, &entry)) {
                        /*
                         * There's a new hole in the address range.
                         */
                        vm_map_unlock_read(map);
                        return KERN_INVALID_ADDRESS;
                }
        }

        vm_map_unlock_read(map);
        return KERN_SUCCESS;
}

static boolean_t
vm_map_entry_is_reusable(
        vm_map_entry_t entry)
{
        /* Only user map entries */

        vm_object_t object;

        if (entry->is_sub_map) {
                return FALSE;
        }

        switch (VME_ALIAS(entry)) {
        case VM_MEMORY_MALLOC:
        case VM_MEMORY_MALLOC_SMALL:
        case VM_MEMORY_MALLOC_LARGE:
        case VM_MEMORY_REALLOC:
        case VM_MEMORY_MALLOC_TINY:
        case VM_MEMORY_MALLOC_LARGE_REUSABLE:
        case VM_MEMORY_MALLOC_LARGE_REUSED:
                /*
                 * This is a malloc() memory region: check if it's still
                 * in its original state and can be re-used for more
                 * malloc() allocations.
                 */
                break;
        default:
                /*
                 * Not a malloc() memory region: let the caller decide if
                 * it's re-usable.
                 */
                return TRUE;
        }

        if (/*entry->is_shared ||*/
                entry->is_sub_map ||
                entry->in_transition ||
                entry->protection != VM_PROT_DEFAULT ||
                entry->max_protection != VM_PROT_ALL ||
                entry->inheritance != VM_INHERIT_DEFAULT ||
                entry->no_cache ||
                entry->permanent ||
                entry->superpage_size != FALSE ||
                entry->zero_wired_pages ||
                entry->wired_count != 0 ||
                entry->user_wired_count != 0) {
                return FALSE;
        }

        object = VME_OBJECT(entry);
        if (object == VM_OBJECT_NULL) {
                return TRUE;
        }
        if (
#if 0
                /*
                 * Let's proceed even if the VM object is potentially
                 * shared.
                 * We check for this later when processing the actual
                 * VM pages, so the contents will be safe if shared.
                 *
                 * But we can still mark this memory region as "reusable" to
                 * acknowledge that the caller did let us know that the memory
                 * could be re-used and should not be penalized for holding
                 * on to it.  This allows its "resident size" to not include
                 * the reusable range.
                 */
                object->ref_count == 1 &&
#endif
                object->wired_page_count == 0 &&
                object->copy == VM_OBJECT_NULL &&
                object->shadow == VM_OBJECT_NULL &&
                object->internal &&
                object->purgable == VM_PURGABLE_DENY &&
                object->copy_strategy != MEMORY_OBJECT_COPY_DELAY &&
                !object->true_share &&
                object->wimg_bits == VM_WIMG_USE_DEFAULT &&
                !object->code_signed) {
                return TRUE;
        }
        return FALSE;
}

static kern_return_t
vm_map_reuse_pages(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end)
{
        vm_map_entry_t                  entry;
        vm_object_t                     object;
        vm_object_offset_t              start_offset, end_offset;

        /*
         * The MADV_REUSE operation doesn't require any changes to the
         * vm_map_entry_t's, so the read lock is sufficient.
         */

        if (VM_MAP_PAGE_SHIFT(map) < PAGE_SHIFT) {
                /*
                 * XXX TODO4K
                 * need to figure out what reusable means for a
                 * portion of a native page.
                 */
                return KERN_SUCCESS;
        }

        vm_map_lock_read(map);
        assert(map->pmap != kernel_pmap);       /* protect alias access */

        /*
         * The madvise semantics require that the address range be fully
         * allocated with no holes.  Otherwise, we're required to return
         * an error.
         */

        if (!vm_map_range_check(map, start, end, &entry)) {
                vm_map_unlock_read(map);
                vm_page_stats_reusable.reuse_pages_failure++;
                return KERN_INVALID_ADDRESS;
        }

        /*
         * Examine each vm_map_entry_t in the range.
         */
        for (; entry != vm_map_to_entry(map) && entry->vme_start < end;
            entry = entry->vme_next) {
                /*
                 * Sanity check on the VM map entry.
                 */
                if (!vm_map_entry_is_reusable(entry)) {
                        vm_map_unlock_read(map);
                        vm_page_stats_reusable.reuse_pages_failure++;
                        return KERN_INVALID_ADDRESS;
                }

                /*
                 * The first time through, the start address could be anywhere
                 * within the vm_map_entry we found.  So adjust the offset to
                 * correspond.
                 */
                if (entry->vme_start < start) {
                        start_offset = start - entry->vme_start;
                } else {
                        start_offset = 0;
                }
                end_offset = MIN(end, entry->vme_end) - entry->vme_start;
                start_offset += VME_OFFSET(entry);
                end_offset += VME_OFFSET(entry);

                assert(!entry->is_sub_map);
                object = VME_OBJECT(entry);
                if (object != VM_OBJECT_NULL) {
                        vm_object_lock(object);
                        vm_object_reuse_pages(object, start_offset, end_offset,
                            TRUE);
                        vm_object_unlock(object);
                }

                if (VME_ALIAS(entry) == VM_MEMORY_MALLOC_LARGE_REUSABLE) {
                        /*
                         * XXX
                         * We do not hold the VM map exclusively here.
                         * The "alias" field is not that critical, so it's
                         * safe to update it here, as long as it is the only
                         * one that can be modified while holding the VM map
                         * "shared".
                         */
                        VME_ALIAS_SET(entry, VM_MEMORY_MALLOC_LARGE_REUSED);
                }
        }

        vm_map_unlock_read(map);
        vm_page_stats_reusable.reuse_pages_success++;
        return KERN_SUCCESS;
}


static kern_return_t
vm_map_reusable_pages(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end)
{
        vm_map_entry_t                  entry;
        vm_object_t                     object;
        vm_object_offset_t              start_offset, end_offset;
        vm_map_offset_t                 pmap_offset;

        if (VM_MAP_PAGE_SHIFT(map) < PAGE_SHIFT) {
                /*
                 * XXX TODO4K
                 * need to figure out what reusable means for a portion
                 * of a native page.
                 */
                return KERN_SUCCESS;
        }

        /*
         * The MADV_REUSABLE operation doesn't require any changes to the
         * vm_map_entry_t's, so the read lock is sufficient.
         */

        vm_map_lock_read(map);
        assert(map->pmap != kernel_pmap);       /* protect alias access */

        /*
         * The madvise semantics require that the address range be fully
         * allocated with no holes.  Otherwise, we're required to return
         * an error.
         */

        if (!vm_map_range_check(map, start, end, &entry)) {
                vm_map_unlock_read(map);
                vm_page_stats_reusable.reusable_pages_failure++;
                return KERN_INVALID_ADDRESS;
        }

        /*
         * Examine each vm_map_entry_t in the range.
         */
        for (; entry != vm_map_to_entry(map) && entry->vme_start < end;
            entry = entry->vme_next) {
                int kill_pages = 0;

                /*
                 * Sanity check on the VM map entry.
                 */
                if (!vm_map_entry_is_reusable(entry)) {
                        vm_map_unlock_read(map);
                        vm_page_stats_reusable.reusable_pages_failure++;
                        return KERN_INVALID_ADDRESS;
                }

                if (!(entry->protection & VM_PROT_WRITE) && !entry->used_for_jit) {
                        /* not writable: can't discard contents */
                        vm_map_unlock_read(map);
                        vm_page_stats_reusable.reusable_nonwritable++;
                        vm_page_stats_reusable.reusable_pages_failure++;
                        return KERN_PROTECTION_FAILURE;
                }

                /*
                 * The first time through, the start address could be anywhere
                 * within the vm_map_entry we found.  So adjust the offset to
                 * correspond.
                 */
                if (entry->vme_start < start) {
                        start_offset = start - entry->vme_start;
                        pmap_offset = start;
                } else {
                        start_offset = 0;
                        pmap_offset = entry->vme_start;
                }
                end_offset = MIN(end, entry->vme_end) - entry->vme_start;
                start_offset += VME_OFFSET(entry);
                end_offset += VME_OFFSET(entry);

                assert(!entry->is_sub_map);
                object = VME_OBJECT(entry);
                if (object == VM_OBJECT_NULL) {
                        continue;
                }


                vm_object_lock(object);
                if (((object->ref_count == 1) ||
                    (object->copy_strategy != MEMORY_OBJECT_COPY_SYMMETRIC &&
                    object->copy == VM_OBJECT_NULL)) &&
                    object->shadow == VM_OBJECT_NULL &&
                    /*
                     * "iokit_acct" entries are billed for their virtual size
                     * (rather than for their resident pages only), so they
                     * wouldn't benefit from making pages reusable, and it
                     * would be hard to keep track of pages that are both
                     * "iokit_acct" and "reusable" in the pmap stats and
                     * ledgers.
                     */
                    !(entry->iokit_acct ||
                    (!entry->is_sub_map && !entry->use_pmap))) {
                        if (object->ref_count != 1) {
                                vm_page_stats_reusable.reusable_shared++;
                        }
                        kill_pages = 1;
                } else {
                        kill_pages = -1;
                }
                if (kill_pages != -1) {
                        vm_object_deactivate_pages(object,
                            start_offset,
                            end_offset - start_offset,
                            kill_pages,
                            TRUE /*reusable_pages*/,
                            map->pmap,
                            pmap_offset);
                } else {
                        vm_page_stats_reusable.reusable_pages_shared++;
                }
                vm_object_unlock(object);

                if (VME_ALIAS(entry) == VM_MEMORY_MALLOC_LARGE ||
                    VME_ALIAS(entry) == VM_MEMORY_MALLOC_LARGE_REUSED) {
                        /*
                         * XXX
                         * We do not hold the VM map exclusively here.
                         * The "alias" field is not that critical, so it's
                         * safe to update it here, as long as it is the only
                         * one that can be modified while holding the VM map
                         * "shared".
                         */
                        VME_ALIAS_SET(entry, VM_MEMORY_MALLOC_LARGE_REUSABLE);
                }
        }

        vm_map_unlock_read(map);
        vm_page_stats_reusable.reusable_pages_success++;
        return KERN_SUCCESS;
}


static kern_return_t
vm_map_can_reuse(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end)
{
        vm_map_entry_t                  entry;

        /*
         * The MADV_REUSABLE operation doesn't require any changes to the
         * vm_map_entry_t's, so the read lock is sufficient.
         */

        vm_map_lock_read(map);
        assert(map->pmap != kernel_pmap);       /* protect alias access */

        /*
         * The madvise semantics require that the address range be fully
         * allocated with no holes.  Otherwise, we're required to return
         * an error.
         */

        if (!vm_map_range_check(map, start, end, &entry)) {
                vm_map_unlock_read(map);
                vm_page_stats_reusable.can_reuse_failure++;
                return KERN_INVALID_ADDRESS;
        }

        /*
         * Examine each vm_map_entry_t in the range.
         */
        for (; entry != vm_map_to_entry(map) && entry->vme_start < end;
            entry = entry->vme_next) {
                /*
                 * Sanity check on the VM map entry.
                 */
                if (!vm_map_entry_is_reusable(entry)) {
                        vm_map_unlock_read(map);
                        vm_page_stats_reusable.can_reuse_failure++;
                        return KERN_INVALID_ADDRESS;
                }
        }

        vm_map_unlock_read(map);
        vm_page_stats_reusable.can_reuse_success++;
        return KERN_SUCCESS;
}


#if MACH_ASSERT
static kern_return_t
vm_map_pageout(
        vm_map_t        map,
        vm_map_offset_t start,
        vm_map_offset_t end)
{
        vm_map_entry_t                  entry;

        /*
         * The MADV_PAGEOUT operation doesn't require any changes to the
         * vm_map_entry_t's, so the read lock is sufficient.
         */

        vm_map_lock_read(map);

        /*
         * The madvise semantics require that the address range be fully
         * allocated with no holes.  Otherwise, we're required to return
         * an error.
         */

        if (!vm_map_range_check(map, start, end, &entry)) {
                vm_map_unlock_read(map);
                return KERN_INVALID_ADDRESS;
        }

        /*
         * Examine each vm_map_entry_t in the range.
         */
        for (; entry != vm_map_to_entry(map) && entry->vme_start < end;
            entry = entry->vme_next) {
                vm_object_t     object;

                /*
                 * Sanity check on the VM map entry.
                 */
                if (entry->is_sub_map) {
                        vm_map_t submap;
                        vm_map_offset_t submap_start;
                        vm_map_offset_t submap_end;
                        vm_map_entry_t submap_entry;

                        submap = VME_SUBMAP(entry);
                        submap_start = VME_OFFSET(entry);
                        submap_end = submap_start + (entry->vme_end -
                            entry->vme_start);

                        vm_map_lock_read(submap);

                        if (!vm_map_range_check(submap,
                            submap_start,
                            submap_end,
                            &submap_entry)) {
                                vm_map_unlock_read(submap);
                                vm_map_unlock_read(map);
                                return KERN_INVALID_ADDRESS;
                        }

                        object = VME_OBJECT(submap_entry);
                        if (submap_entry->is_sub_map ||
                            object == VM_OBJECT_NULL ||
                            !object->internal) {
                                vm_map_unlock_read(submap);
                                continue;
                        }

                        vm_object_pageout(object);

                        vm_map_unlock_read(submap);
                        submap = VM_MAP_NULL;
                        submap_entry = VM_MAP_ENTRY_NULL;
                        continue;
                }

                object = VME_OBJECT(entry);
                if (entry->is_sub_map ||
                    object == VM_OBJECT_NULL ||
                    !object->internal) {
                        continue;
                }

                vm_object_pageout(object);
        }

        vm_map_unlock_read(map);
        return KERN_SUCCESS;
}
#endif /* MACH_ASSERT */


/*
 *      Routine:        vm_map_entry_insert
 *
 *      Description:    This routine inserts a new vm_entry in a locked map.
 */
vm_map_entry_t
vm_map_entry_insert(
        vm_map_t                map,
        vm_map_entry_t          insp_entry,
        vm_map_offset_t         start,
        vm_map_offset_t         end,
        vm_object_t             object,
        vm_object_offset_t      offset,
        boolean_t               needs_copy,
        boolean_t               is_shared,
        boolean_t               in_transition,
        vm_prot_t               cur_protection,
        vm_prot_t               max_protection,
        vm_behavior_t           behavior,
        vm_inherit_t            inheritance,
        unsigned short          wired_count,
        boolean_t               no_cache,
        boolean_t               permanent,
        boolean_t               no_copy_on_read,
        unsigned int            superpage_size,
        boolean_t               clear_map_aligned,
        boolean_t               is_submap,
        boolean_t               used_for_jit,
        int                     alias,
        boolean_t               translated_allow_execute)
{
        vm_map_entry_t  new_entry;

        assert(insp_entry != (vm_map_entry_t)0);
        vm_map_lock_assert_exclusive(map);

#if DEVELOPMENT || DEBUG
        vm_object_offset_t      end_offset = 0;
        assertf(!os_add_overflow(end - start, offset, &end_offset), "size 0x%llx, offset 0x%llx caused overflow", (uint64_t)(end - start), offset);
#endif /* DEVELOPMENT || DEBUG */

        new_entry = vm_map_entry_create(map, !map->hdr.entries_pageable);

        if (VM_MAP_PAGE_SHIFT(map) != PAGE_SHIFT) {
                new_entry->map_aligned = TRUE;
        } else {
                new_entry->map_aligned = FALSE;
        }
        if (clear_map_aligned &&
            (!VM_MAP_PAGE_ALIGNED(start, VM_MAP_PAGE_MASK(map)) ||
            !VM_MAP_PAGE_ALIGNED(end, VM_MAP_PAGE_MASK(map)))) {
                new_entry->map_aligned = FALSE;
        }

        new_entry->vme_start = start;
        new_entry->vme_end = end;
        if (new_entry->map_aligned) {
                assert(VM_MAP_PAGE_ALIGNED(new_entry->vme_start,
                    VM_MAP_PAGE_MASK(map)));
                assert(VM_MAP_PAGE_ALIGNED(new_entry->vme_end,
                    VM_MAP_PAGE_MASK(map)));
        } else {
                assert(page_aligned(new_entry->vme_start));
                assert(page_aligned(new_entry->vme_end));
        }
        assert(new_entry->vme_start < new_entry->vme_end);

        VME_OBJECT_SET(new_entry, object);
        VME_OFFSET_SET(new_entry, offset);
        new_entry->is_shared = is_shared;
        new_entry->is_sub_map = is_submap;
        new_entry->needs_copy = needs_copy;
        new_entry->in_transition = in_transition;
        new_entry->needs_wakeup = FALSE;
        new_entry->inheritance = inheritance;
        new_entry->protection = cur_protection;
        new_entry->max_protection = max_protection;
        new_entry->behavior = behavior;
        new_entry->wired_count = wired_count;
        new_entry->user_wired_count = 0;
        if (is_submap) {
                /*
                 * submap: "use_pmap" means "nested".
                 * default: false.
                 */
                new_entry->use_pmap = FALSE;
        } else {
                /*
                 * object: "use_pmap" means "use pmap accounting" for footprint.
                 * default: true.
                 */
                new_entry->use_pmap = TRUE;
        }
        VME_ALIAS_SET(new_entry, alias);
        new_entry->zero_wired_pages = FALSE;
        new_entry->no_cache = no_cache;
        new_entry->permanent = permanent;
        if (superpage_size) {
                new_entry->superpage_size = TRUE;
        } else {
                new_entry->superpage_size = FALSE;
        }
        if (used_for_jit) {
                if (!(map->jit_entry_exists) ||
                    VM_MAP_POLICY_ALLOW_MULTIPLE_JIT(map)) {
                        new_entry->used_for_jit = TRUE;
                        map->jit_entry_exists = TRUE;
                }
        } else {
                new_entry->used_for_jit = FALSE;
        }
        if (translated_allow_execute) {
                new_entry->translated_allow_execute = TRUE;
        } else {
                new_entry->translated_allow_execute = FALSE;
        }
        new_entry->pmap_cs_associated = FALSE;
        new_entry->iokit_acct = FALSE;
        new_entry->vme_resilient_codesign = FALSE;
        new_entry->vme_resilient_media = FALSE;
        new_entry->vme_atomic = FALSE;
        new_entry->vme_no_copy_on_read = no_copy_on_read;

        /*
         *      Insert the new entry into the list.
         */

        vm_map_store_entry_link(map, insp_entry, new_entry,
            VM_MAP_KERNEL_FLAGS_NONE);
        map->size += end - start;

        /*
         *      Update the free space hint and the lookup hint.
         */

        SAVE_HINT_MAP_WRITE(map, new_entry);
        return new_entry;
}

int vm_remap_old_path = 0;
int vm_remap_new_path = 0;
/*
 *      Routine:        vm_map_remap_extract
 *
 *      Description:    This routine returns a vm_entry list from a map.
 */
static kern_return_t
vm_map_remap_extract(
        vm_map_t                map,
        vm_map_offset_t         addr,
        vm_map_size_t           size,
        vm_prot_t               required_protection,
        boolean_t               copy,
        struct vm_map_header    *map_header,
        vm_prot_t               *cur_protection,
        vm_prot_t               *max_protection,
        /* What, no behavior? */
        vm_inherit_t            inheritance,
        vm_map_kernel_flags_t   vmk_flags)
{
        kern_return_t           result;
        vm_map_size_t           mapped_size;
        vm_map_size_t           tmp_size;
        vm_map_entry_t          src_entry;     /* result of last map lookup */
        vm_map_entry_t          new_entry;
        vm_object_offset_t      offset;
        vm_map_offset_t         map_address;
        vm_map_offset_t         src_start;     /* start of entry to map */
        vm_map_offset_t         src_end;       /* end of region to be mapped */
        vm_object_t             object;
        vm_map_version_t        version;
        boolean_t               src_needs_copy;
        boolean_t               new_entry_needs_copy;
        vm_map_entry_t          saved_src_entry;
        boolean_t               src_entry_was_wired;
        vm_prot_t               max_prot_for_prot_copy;
        vm_map_offset_t         effective_page_mask;
        boolean_t               pageable, same_map;

        pageable = vmk_flags.vmkf_copy_pageable;
        same_map = vmk_flags.vmkf_copy_same_map;

        effective_page_mask = MIN(PAGE_MASK, VM_MAP_PAGE_MASK(map));

        assert(map != VM_MAP_NULL);
        assert(size != 0);
        assert(size == vm_map_round_page(size, effective_page_mask));
        assert(inheritance == VM_INHERIT_NONE ||
            inheritance == VM_INHERIT_COPY ||
            inheritance == VM_INHERIT_SHARE);
        assert(!(required_protection & ~VM_PROT_ALL));

        /*
         *      Compute start and end of region.
         */
        src_start = vm_map_trunc_page(addr, effective_page_mask);
        src_end = vm_map_round_page(src_start + size, effective_page_mask);

        /*
         *      Initialize map_header.
         */
        map_header->links.next = CAST_TO_VM_MAP_ENTRY(&map_header->links);
        map_header->links.prev = CAST_TO_VM_MAP_ENTRY(&map_header->links);
        map_header->nentries = 0;
        map_header->entries_pageable = pageable;
//      map_header->page_shift = MIN(VM_MAP_PAGE_SHIFT(map), PAGE_SHIFT);
        map_header->page_shift = VM_MAP_PAGE_SHIFT(map);
        map_header->rb_head_store.rbh_root = (void *)(int)SKIP_RB_TREE;

        vm_map_store_init( map_header );

        if (copy && vmk_flags.vmkf_remap_prot_copy) {
                max_prot_for_prot_copy = *max_protection & VM_PROT_ALL;
        } else {
                max_prot_for_prot_copy = VM_PROT_NONE;
        }
        *cur_protection = VM_PROT_ALL;
        *max_protection = VM_PROT_ALL;

        map_address = 0;
        mapped_size = 0;
        result = KERN_SUCCESS;

        /*
         *      The specified source virtual space might correspond to
         *      multiple map entries, need to loop on them.
         */
        vm_map_lock(map);
        if (VM_MAP_PAGE_SHIFT(map) < PAGE_SHIFT) {
                /*
                 * This address space uses sub-pages so the range might
                 * not be re-mappable in an address space with larger
                 * pages. Re-assemble any broken-up VM map entries to
                 * improve our chances of making it work.
                 */
                vm_map_simplify_range(map, src_start, src_end);
        }
        while (mapped_size != size) {
                vm_map_size_t   entry_size;

                /*
                 *      Find the beginning of the region.
                 */
                if (!vm_map_lookup_entry(map, src_start, &src_entry)) {
                        result = KERN_INVALID_ADDRESS;
                        break;
                }

                if (src_start < src_entry->vme_start ||
                    (mapped_size && src_start != src_entry->vme_start)) {
                        result = KERN_INVALID_ADDRESS;
                        break;
                }

                tmp_size = size - mapped_size;
                if (src_end > src_entry->vme_end) {
                        tmp_size -= (src_end - src_entry->vme_end);
                }

                entry_size = (vm_map_size_t)(src_entry->vme_end -
                    src_entry->vme_start);

                if (src_entry->is_sub_map &&
                    vmk_flags.vmkf_copy_single_object) {
                        vm_map_t submap;
                        vm_map_offset_t submap_start;
                        vm_map_size_t submap_size;

                        /*
                         * No check for "required_protection" on "src_entry"
                         * because the protections that matter are the ones
                         * on the submap's VM map entry, which will be checked
                         * during the call to vm_map_remap_extract() below.
                         */
                        submap_size = src_entry->vme_end - src_start;
                        if (submap_size > size) {
                                submap_size = size;
                        }
                        submap_start = VME_OFFSET(src_entry) + src_start - src_entry->vme_start;
                        submap = VME_SUBMAP(src_entry);
                        vm_map_reference(submap);
                        vm_map_unlock(map);
                        src_entry = NULL;
                        result = vm_map_remap_extract(submap,
                            submap_start,
                            submap_size,
                            required_protection,
                            copy,
                            map_header,
                            cur_protection,
                            max_protection,
                            inheritance,
                            vmk_flags);
                        vm_map_deallocate(submap);
                        return result;
                }

                if ((src_entry->protection & required_protection)
                    != required_protection) {
                        if (vmk_flags.vmkf_copy_single_object &&
                            mapped_size != 0) {
                                /*
                                 * Single object extraction.
                                 * We can't extract more with the required
                                 * protection but we've extracted some, so
                                 * stop there and declare success.
                                 * The caller should check the size of
                                 * the copy entry we've extracted.
                                 */
                                result = KERN_SUCCESS;
                        } else {
                                /*
                                 * VM range extraction.
                                 * Required proctection is not available
                                 * for this part of the range: fail.
                                 */
                                result = KERN_PROTECTION_FAILURE;
                        }
                        break;
                }

                if (src_entry->is_sub_map &&
                    VM_MAP_PAGE_SHIFT(VME_SUBMAP(src_entry)) < PAGE_SHIFT) {
                        vm_map_t submap;
                        vm_map_offset_t submap_start;
                        vm_map_size_t submap_size;
                        vm_map_copy_t submap_copy;
                        vm_prot_t submap_curprot, submap_maxprot;

                        vm_remap_new_path++;

                        /*
                         * No check for "required_protection" on "src_entry"
                         * because the protections that matter are the ones
                         * on the submap's VM map entry, which will be checked
                         * during the call to vm_map_copy_extract() below.
                         */
                        object = VM_OBJECT_NULL;
                        submap_copy = VM_MAP_COPY_NULL;

                        /* find equivalent range in the submap */
                        submap = VME_SUBMAP(src_entry);
                        submap_start = VME_OFFSET(src_entry) + src_start - src_entry->vme_start;
                        submap_size = tmp_size;
                        /* extra ref to keep submap alive */
                        vm_map_reference(submap);

                        DTRACE_VM6(remap_submap_recurse,
                            vm_map_t, map,
                            vm_map_offset_t, addr,
                            vm_map_size_t, size,
                            boolean_t, copy,
                            vm_map_offset_t, submap_start,
                            vm_map_size_t, submap_size);

                        /*
                         * The map can be safely unlocked since we
                         * already hold a reference on the submap.
                         *
                         * No timestamp since we don't care if the map
                         * gets modified while we're down in the submap.
                         * We'll resume the extraction at src_start + tmp_size
                         * anyway.
                         */
                        vm_map_unlock(map);
                        src_entry = NULL; /* not valid once map is unlocked */

                        result = vm_map_copy_extract(submap,
                            submap_start,
                            submap_size,
                            required_protection,
                            copy,
                            &submap_copy,
                            &submap_curprot,
                            &submap_maxprot,
                            inheritance,
                            vmk_flags);

                        /* release extra ref on submap */
                        vm_map_deallocate(submap);
                        submap = VM_MAP_NULL;

                        if (result != KERN_SUCCESS) {
                                vm_map_lock(map);
                                break;
                        }

                        /* transfer submap_copy entries to map_header */
                        while (vm_map_copy_first_entry(submap_copy) !=
                            vm_map_copy_to_entry(submap_copy)) {
                                vm_map_entry_t copy_entry;
                                vm_map_size_t copy_entry_size;

                                copy_entry = vm_map_copy_first_entry(submap_copy);
                                assert(!copy_entry->is_sub_map);
                                vm_map_copy_entry_unlink(submap_copy, copy_entry);
                                copy_entry_size = copy_entry->vme_end - copy_entry->vme_start;
                                copy_entry->vme_start = map_address;
                                copy_entry->vme_end = map_address + copy_entry_size;
                                map_address += copy_entry_size;
                                mapped_size += copy_entry_size;
                                src_start += copy_entry_size;
                                assert(src_start <= src_end);
                                _vm_map_store_entry_link(map_header,
                                    map_header->links.prev,
                                    copy_entry);
                        }
                        /* done with submap_copy */
                        vm_map_copy_discard(submap_copy);

                        *cur_protection &= submap_curprot;
                        *max_protection &= submap_maxprot;

                        /* re-acquire the map lock and continue to next entry */
                        vm_map_lock(map);
                        continue;
                } else if (src_entry->is_sub_map) {
                        vm_remap_old_path++;
                        DTRACE_VM4(remap_submap,
                            vm_map_t, map,
                            vm_map_offset_t, addr,
                            vm_map_size_t, size,
                            boolean_t, copy);

                        vm_map_reference(VME_SUBMAP(src_entry));
                        object = VM_OBJECT_NULL;
                } else {
                        object = VME_OBJECT(src_entry);
                        if (src_entry->iokit_acct) {
                                /*
                                 * This entry uses "IOKit accounting".
                                 */
                        } else if (object != VM_OBJECT_NULL &&
                            (object->purgable != VM_PURGABLE_DENY ||
                            object->vo_ledger_tag != VM_LEDGER_TAG_NONE)) {
                                /*
                                 * Purgeable objects have their own accounting:
                                 * no pmap accounting for them.
                                 */
                                assertf(!src_entry->use_pmap,
                                    "map=%p src_entry=%p [0x%llx:0x%llx] 0x%x/0x%x %d",
                                    map,
                                    src_entry,
                                    (uint64_t)src_entry->vme_start,
                                    (uint64_t)src_entry->vme_end,
                                    src_entry->protection,
                                    src_entry->max_protection,
                                    VME_ALIAS(src_entry));
                        } else {
                                /*
                                 * Not IOKit or purgeable:
                                 * must be accounted by pmap stats.
                                 */
                                assertf(src_entry->use_pmap,
                                    "map=%p src_entry=%p [0x%llx:0x%llx] 0x%x/0x%x %d",
                                    map,
                                    src_entry,
                                    (uint64_t)src_entry->vme_start,
                                    (uint64_t)src_entry->vme_end,
                                    src_entry->protection,
                                    src_entry->max_protection,
                                    VME_ALIAS(src_entry));
                        }

                        if (object == VM_OBJECT_NULL) {
                                assert(!src_entry->needs_copy);
                                object = vm_object_allocate(entry_size);
                                VME_OFFSET_SET(src_entry, 0);
                                VME_OBJECT_SET(src_entry, object);
                                assert(src_entry->use_pmap);
                        } else if (src_entry->wired_count ||
                            object->copy_strategy != MEMORY_OBJECT_COPY_SYMMETRIC) {
                                /*
                                 * A wired memory region should not have
                                 * any pending copy-on-write and needs to
                                 * keep pointing at the VM object that
                                 * contains the wired pages.
                                 * If we're sharing this memory (copy=false),
                                 * we'll share this VM object.
                                 * If we're copying this memory (copy=true),
                                 * we'll call vm_object_copy_slowly() below
                                 * and use the new VM object for the remapping.
                                 *
                                 * Or, we are already using an asymmetric
                                 * copy, and therefore we already have
                                 * the right object.
                                 */
                                assert(!src_entry->needs_copy);
                        } else if (src_entry->needs_copy || object->shadowed ||
                            (object->internal && !object->true_share &&
                            !src_entry->is_shared &&
                            object->vo_size > entry_size)) {
                                VME_OBJECT_SHADOW(src_entry, entry_size);
                                assert(src_entry->use_pmap);

                                if (!src_entry->needs_copy &&
                                    (src_entry->protection & VM_PROT_WRITE)) {
                                        vm_prot_t prot;

                                        assert(!pmap_has_prot_policy(map->pmap, src_entry->translated_allow_execute, src_entry->protection));

                                        prot = src_entry->protection & ~VM_PROT_WRITE;

                                        if (override_nx(map,
                                            VME_ALIAS(src_entry))
                                            && prot) {
                                                prot |= VM_PROT_EXECUTE;
                                        }

                                        assert(!pmap_has_prot_policy(map->pmap, src_entry->translated_allow_execute, prot));

                                        if (map->mapped_in_other_pmaps) {
                                                vm_object_pmap_protect(
                                                        VME_OBJECT(src_entry),
                                                        VME_OFFSET(src_entry),
                                                        entry_size,
                                                        PMAP_NULL,
                                                        PAGE_SIZE,
                                                        src_entry->vme_start,
                                                        prot);
#if MACH_ASSERT
                                        } else if (__improbable(map->pmap == PMAP_NULL)) {
                                                extern boolean_t vm_tests_in_progress;
                                                assert(vm_tests_in_progress);
                                                /*
                                                 * Some VM tests (in vm_tests.c)
                                                 * sometimes want to use a VM
                                                 * map without a pmap.
                                                 * Otherwise, this should never
                                                 * happen.
                                                 */
#endif /* MACH_ASSERT */
                                        } else {
                                                pmap_protect(vm_map_pmap(map),
                                                    src_entry->vme_start,
                                                    src_entry->vme_end,
                                                    prot);
                                        }
                                }

                                object = VME_OBJECT(src_entry);
                                src_entry->needs_copy = FALSE;
                        }


                        vm_object_lock(object);
                        vm_object_reference_locked(object); /* object ref. for new entry */
                        assert(!src_entry->needs_copy);
                        if (object->copy_strategy ==
                            MEMORY_OBJECT_COPY_SYMMETRIC) {
                                /*
                                 * If we want to share this object (copy==0),
                                 * it needs to be COPY_DELAY.
                                 * If we want to copy this object (copy==1),
                                 * we can't just set "needs_copy" on our side
                                 * and expect the other side to do the same
                                 * (symmetrically), so we can't let the object
                                 * stay COPY_SYMMETRIC.
                                 * So we always switch from COPY_SYMMETRIC to
                                 * COPY_DELAY.
                                 */
                                object->copy_strategy =
                                    MEMORY_OBJECT_COPY_DELAY;
                        }
                        vm_object_unlock(object);
                }

                offset = (VME_OFFSET(src_entry) +
                    (src_start - src_entry->vme_start));

                new_entry = _vm_map_entry_create(map_header, !map_header->entries_pageable);
                vm_map_entry_copy(map, new_entry, src_entry);
                if (new_entry->is_sub_map) {
                        /* clr address space specifics */
                        new_entry->use_pmap = FALSE;
                } else if (copy) {
                        /*
                         * We're dealing with a copy-on-write operation,
                         * so the resulting mapping should not inherit the
                         * original mapping's accounting settings.
                         * "use_pmap" should be reset to its default (TRUE)
                         * so that the new mapping gets accounted for in
                         * the task's memory footprint.
                         */
                        new_entry->use_pmap = TRUE;
                }
                /* "iokit_acct" was cleared in vm_map_entry_copy() */
                assert(!new_entry->iokit_acct);

                new_entry->map_aligned = FALSE;

                new_entry->vme_start = map_address;
                new_entry->vme_end = map_address + tmp_size;
                assert(new_entry->vme_start < new_entry->vme_end);
                if (copy && vmk_flags.vmkf_remap_prot_copy) {
                        /*
                         * Remapping for vm_map_protect(VM_PROT_COPY)
                         * to convert a read-only mapping into a
                         * copy-on-write version of itself but
                         * with write access:
                         * keep the original inheritance and add
                         * VM_PROT_WRITE to the max protection.
                         */
                        new_entry->inheritance = src_entry->inheritance;
                        new_entry->protection &= max_prot_for_prot_copy;
                        new_entry->max_protection |= VM_PROT_WRITE;
                } else {
                        new_entry->inheritance = inheritance;
                }
                VME_OFFSET_SET(new_entry, offset);

                /*
                 * The new region has to be copied now if required.
                 */
RestartCopy:
                if (!copy) {
                        if (src_entry->used_for_jit == TRUE) {
                                if (same_map) {
#if __APRR_SUPPORTED__
                                        /*
                                         * Disallow re-mapping of any JIT regions on APRR devices.
                                         */
                                        result = KERN_PROTECTION_FAILURE;
                                        break;
#endif /* __APRR_SUPPORTED__*/
                                } else if (!VM_MAP_POLICY_ALLOW_JIT_SHARING(map)) {
                                        /*
                                         * Cannot allow an entry describing a JIT
                                         * region to be shared across address spaces.
                                         */
                                        result = KERN_INVALID_ARGUMENT;
                                        break;
                                }
                        }

                        src_entry->is_shared = TRUE;
                        new_entry->is_shared = TRUE;
                        if (!(new_entry->is_sub_map)) {
                                new_entry->needs_copy = FALSE;
                        }
                } else if (src_entry->is_sub_map) {
                        /* make this a COW sub_map if not already */
                        assert(new_entry->wired_count == 0);
                        new_entry->needs_copy = TRUE;
                        object = VM_OBJECT_NULL;
                } else if (src_entry->wired_count == 0 &&
                    !(debug4k_no_cow_copyin && VM_MAP_PAGE_SHIFT(map) < PAGE_SHIFT) &&
                    vm_object_copy_quickly(VME_OBJECT_PTR(new_entry),
                    VME_OFFSET(new_entry),
                    (new_entry->vme_end -
                    new_entry->vme_start),
                    &src_needs_copy,
                    &new_entry_needs_copy)) {
                        new_entry->needs_copy = new_entry_needs_copy;
                        new_entry->is_shared = FALSE;
                        assertf(new_entry->use_pmap, "map %p new_entry %p\n", map, new_entry);

                        /*
                         * Handle copy_on_write semantics.
                         */
                        if (src_needs_copy && !src_entry->needs_copy) {
                                vm_prot_t prot;

                                assert(!pmap_has_prot_policy(map->pmap, src_entry->translated_allow_execute, src_entry->protection));

                                prot = src_entry->protection & ~VM_PROT_WRITE;

                                if (override_nx(map,
                                    VME_ALIAS(src_entry))
                                    && prot) {
                                        prot |= VM_PROT_EXECUTE;
                                }

                                assert(!pmap_has_prot_policy(map->pmap, src_entry->translated_allow_execute, prot));

                                vm_object_pmap_protect(object,
                                    offset,
                                    entry_size,
                                    ((src_entry->is_shared
                                    || map->mapped_in_other_pmaps) ?
                                    PMAP_NULL : map->pmap),
                                    VM_MAP_PAGE_SIZE(map),
                                    src_entry->vme_start,
                                    prot);

                                assert(src_entry->wired_count == 0);
                                src_entry->needs_copy = TRUE;
                        }
                        /*
                         * Throw away the old object reference of the new entry.
                         */
                        vm_object_deallocate(object);
                } else {
                        new_entry->is_shared = FALSE;
                        assertf(new_entry->use_pmap, "map %p new_entry %p\n", map, new_entry);

                        src_entry_was_wired = (src_entry->wired_count > 0);
                        saved_src_entry = src_entry;
                        src_entry = VM_MAP_ENTRY_NULL;

                        /*
                         * The map can be safely unlocked since we
                         * already hold a reference on the object.
                         *
                         * Record the timestamp of the map for later
                         * verification, and unlock the map.
                         */
                        version.main_timestamp = map->timestamp;
                        vm_map_unlock(map);     /* Increments timestamp once! */

                        /*
                         * Perform the copy.
                         */
                        if (src_entry_was_wired > 0 ||
                            (debug4k_no_cow_copyin &&
                            VM_MAP_PAGE_SHIFT(map) < PAGE_SHIFT)) {
                                vm_object_lock(object);
                                result = vm_object_copy_slowly(
                                        object,
                                        offset,
                                        (new_entry->vme_end -
                                        new_entry->vme_start),
                                        THREAD_UNINT,
                                        VME_OBJECT_PTR(new_entry));

                                VME_OFFSET_SET(new_entry, offset - vm_object_trunc_page(offset));
                                new_entry->needs_copy = FALSE;
                        } else {
                                vm_object_offset_t new_offset;

                                new_offset = VME_OFFSET(new_entry);
                                result = vm_object_copy_strategically(
                                        object,
                                        offset,
                                        (new_entry->vme_end -
                                        new_entry->vme_start),
                                        VME_OBJECT_PTR(new_entry),
                                        &new_offset,
                                        &new_entry_needs_copy);
                                if (new_offset != VME_OFFSET(new_entry)) {
                                        VME_OFFSET_SET(new_entry, new_offset);
                                }

                                new_entry->needs_copy = new_entry_needs_copy;
                        }

                        /*
                         * Throw away the old object reference of the new entry.
                         */
                        vm_object_deallocate(object);

                        if (result != KERN_SUCCESS &&
                            result != KERN_MEMORY_RESTART_COPY) {
                                _vm_map_entry_dispose(map_header, new_entry);
                                vm_map_lock(map);
                                break;
                        }

                        /*
                         * Verify that the map has not substantially
                         * changed while the copy was being made.
                         */

                        vm_map_lock(map);
                        if (version.main_timestamp + 1 != map->timestamp) {
                                /*
                                 * Simple version comparison failed.
                                 *
                                 * Retry the lookup and verify that the
                                 * same object/offset are still present.
                                 */
                                saved_src_entry = VM_MAP_ENTRY_NULL;
                                vm_object_deallocate(VME_OBJECT(new_entry));
                                _vm_map_entry_dispose(map_header, new_entry);
                                if (result == KERN_MEMORY_RESTART_COPY) {
                                        result = KERN_SUCCESS;
                                }
                                continue;
                        }
                        /* map hasn't changed: src_entry is still valid */
                        src_entry = saved_src_entry;
                        saved_src_entry = VM_MAP_ENTRY_NULL;

                        if (result == KERN_MEMORY_RESTART_COPY) {
                                vm_object_reference(object);
                                goto RestartCopy;
                        }
                }

                _vm_map_store_entry_link(map_header,
                    map_header->links.prev, new_entry);

                /*Protections for submap mapping are irrelevant here*/
                if (!src_entry->is_sub_map) {
                        *cur_protection &= src_entry->protection;
                        *max_protection &= src_entry->max_protection;
                }

                map_address += tmp_size;
                mapped_size += tmp_size;
                src_start += tmp_size;

                if (vmk_flags.vmkf_copy_single_object) {
                        if (mapped_size != size) {
                                DEBUG4K_SHARE("map %p addr 0x%llx size 0x%llx clipped copy at mapped_size 0x%llx\n", map, (uint64_t)addr, (uint64_t)size, (uint64_t)mapped_size);
                                if (src_entry->vme_next != vm_map_to_entry(map) &&
                                    VME_OBJECT(src_entry->vme_next) == VME_OBJECT(src_entry)) {
                                        /* XXX TODO4K */
                                        DEBUG4K_ERROR("could have extended copy to next entry...\n");
                                }
                        }
                        break;
                }
        } /* end while */

        vm_map_unlock(map);
        if (result != KERN_SUCCESS) {
                /*
                 * Free all allocated elements.
                 */
                for (src_entry = map_header->links.next;
                    src_entry != CAST_TO_VM_MAP_ENTRY(&map_header->links);
                    src_entry = new_entry) {
                        new_entry = src_entry->vme_next;
                        _vm_map_store_entry_unlink(map_header, src_entry);
                        if (src_entry->is_sub_map) {
                                vm_map_deallocate(VME_SUBMAP(src_entry));
                        } else {
                                vm_object_deallocate(VME_OBJECT(src_entry));
                        }
                        _vm_map_entry_dispose(map_header, src_entry);
                }
        }
        return result;
}

bool
vm_map_is_exotic(
        vm_map_t map)
{
        return VM_MAP_IS_EXOTIC(map);
}

bool
vm_map_is_alien(
        vm_map_t map)
{
        return VM_MAP_IS_ALIEN(map);
}

#if XNU_TARGET_OS_OSX
void
vm_map_mark_alien(
        vm_map_t map)
{
        vm_map_lock(map);
        map->is_alien = true;
        vm_map_unlock(map);
}
#endif /* XNU_TARGET_OS_OSX */

void vm_map_copy_to_physcopy(vm_map_copy_t copy_map, vm_map_t target_map);
void
vm_map_copy_to_physcopy(
        vm_map_copy_t   copy_map,
        vm_map_t        target_map)
{
        vm_map_size_t           size;
        vm_map_entry_t          entry;
        vm_map_entry_t          new_entry;
        vm_object_t             new_object;
        unsigned int            pmap_flags;
        pmap_t                  new_pmap;
        vm_map_t                new_map;
        vm_map_address_t        src_start, src_end, src_cur;
        vm_map_address_t        dst_start, dst_end, dst_cur;
        kern_return_t           kr;
        void                    *kbuf;

        /*
         * Perform the equivalent of vm_allocate() and memcpy().
         * Replace the mappings in "copy_map" with the newly allocated mapping.
         */
        DEBUG4K_COPY("copy_map %p (%d %d 0x%llx 0x%llx) BEFORE\n", copy_map, copy_map->cpy_hdr.page_shift, copy_map->cpy_hdr.nentries, copy_map->offset, (uint64_t)copy_map->size);

        assert(copy_map->cpy_hdr.page_shift != VM_MAP_PAGE_MASK(target_map));

        /* allocate new VM object */
        size = VM_MAP_ROUND_PAGE(copy_map->size, PAGE_MASK);
        new_object = vm_object_allocate(size);
        assert(new_object);

        /* allocate new VM map entry */
        new_entry = vm_map_copy_entry_create(copy_map, FALSE);
        assert(new_entry);

        /* finish initializing new VM map entry */
        new_entry->protection = VM_PROT_DEFAULT;
        new_entry->max_protection = VM_PROT_DEFAULT;
        new_entry->use_pmap = TRUE;

        /* make new VM map entry point to new VM object */
        new_entry->vme_start = 0;
        new_entry->vme_end = size;
        VME_OBJECT_SET(new_entry, new_object);
        VME_OFFSET_SET(new_entry, 0);

        /* create a new pmap to map "copy_map" */
        pmap_flags = 0;
        assert(copy_map->cpy_hdr.page_shift == FOURK_PAGE_SHIFT);
#if PMAP_CREATE_FORCE_4K_PAGES
        pmap_flags |= PMAP_CREATE_FORCE_4K_PAGES;
#endif /* PMAP_CREATE_FORCE_4K_PAGES */
        pmap_flags |= PMAP_CREATE_64BIT;
        new_pmap = pmap_create_options(NULL, (vm_map_size_t)0, pmap_flags);
        assert(new_pmap);

        /* create a new pageable VM map to map "copy_map" */
        new_map = vm_map_create(new_pmap, 0, MACH_VM_MAX_ADDRESS, TRUE);
        assert(new_map);
        vm_map_set_page_shift(new_map, copy_map->cpy_hdr.page_shift);

        /* map "copy_map" in the new VM map */
        src_start = 0;
        kr = vm_map_copyout_internal(
                new_map,
                &src_start,
                copy_map,
                copy_map->size,
                FALSE, /* consume_on_success */
                VM_PROT_DEFAULT,
                VM_PROT_DEFAULT,
                VM_INHERIT_DEFAULT);
        assert(kr == KERN_SUCCESS);
        src_end = src_start + copy_map->size;

        /* map "new_object" in the new VM map */
        vm_object_reference(new_object);
        dst_start = 0;
        kr = vm_map_enter(new_map,
            &dst_start,
            size,
            0,               /* mask */
            VM_FLAGS_ANYWHERE,
            VM_MAP_KERNEL_FLAGS_NONE,
            VM_KERN_MEMORY_OSFMK,
            new_object,
            0,               /* offset */
            FALSE,               /* needs copy */
            VM_PROT_DEFAULT,
            VM_PROT_DEFAULT,
            VM_INHERIT_DEFAULT);
        assert(kr == KERN_SUCCESS);
        dst_end = dst_start + size;

        /* get a kernel buffer */
        kbuf = kheap_alloc(KHEAP_TEMP, PAGE_SIZE, Z_WAITOK);
        assert(kbuf);

        /* physically copy "copy_map" mappings to new VM object */
        for (src_cur = src_start, dst_cur = dst_start;
            src_cur < src_end;
            src_cur += PAGE_SIZE, dst_cur += PAGE_SIZE) {
                vm_size_t bytes;

                bytes = PAGE_SIZE;
                if (src_cur + PAGE_SIZE > src_end) {
                        /* partial copy for last page */
                        bytes = src_end - src_cur;
                        assert(bytes > 0 && bytes < PAGE_SIZE);
                        /* rest of dst page should be zero-filled */
                }
                /* get bytes from src mapping */
                kr = copyinmap(new_map, src_cur, kbuf, bytes);
                if (kr != KERN_SUCCESS) {
                        DEBUG4K_COPY("copyinmap(%p, 0x%llx, %p, 0x%llx) kr 0x%x\n", new_map, (uint64_t)src_cur, kbuf, (uint64_t)bytes, kr);
                }
                /* put bytes in dst mapping */
                assert(dst_cur < dst_end);
                assert(dst_cur + bytes <= dst_end);
                kr = copyoutmap(new_map, kbuf, dst_cur, bytes);
                if (kr != KERN_SUCCESS) {
                        DEBUG4K_COPY("copyoutmap(%p, %p, 0x%llx, 0x%llx) kr 0x%x\n", new_map, kbuf, (uint64_t)dst_cur, (uint64_t)bytes, kr);
                }
        }

        /* free kernel buffer */
        kheap_free(KHEAP_TEMP, kbuf, PAGE_SIZE);
        kbuf = NULL;

        /* destroy new map */
        vm_map_destroy(new_map, VM_MAP_REMOVE_NO_FLAGS);
        new_map = VM_MAP_NULL;

        /* dispose of the old map entries in "copy_map" */
        while (vm_map_copy_first_entry(copy_map) !=
            vm_map_copy_to_entry(copy_map)) {
                entry = vm_map_copy_first_entry(copy_map);
                vm_map_copy_entry_unlink(copy_map, entry);
                if (entry->is_sub_map) {
                        vm_map_deallocate(VME_SUBMAP(entry));
                } else {
                        vm_object_deallocate(VME_OBJECT(entry));
                }
                vm_map_copy_entry_dispose(copy_map, entry);
        }

        /* change "copy_map"'s page_size to match "target_map" */
        copy_map->cpy_hdr.page_shift = VM_MAP_PAGE_SHIFT(target_map);
        copy_map->offset = 0;
        copy_map->size = size;

        /* insert new map entry in "copy_map" */
        assert(vm_map_copy_last_entry(copy_map) == vm_map_copy_to_entry(copy_map));
        vm_map_copy_entry_link(copy_map, vm_map_copy_last_entry(copy_map), new_entry);

        DEBUG4K_COPY("copy_map %p (%d %d 0x%llx 0x%llx) AFTER\n", copy_map, copy_map->cpy_hdr.page_shift, copy_map->cpy_hdr.nentries, copy_map->offset, (uint64_t)copy_map->size);
}

void
vm_map_copy_adjust_get_target_copy_map(
        vm_map_copy_t   copy_map,
        vm_map_copy_t   *target_copy_map_p);
void
vm_map_copy_adjust_get_target_copy_map(
        vm_map_copy_t   copy_map,
        vm_map_copy_t   *target_copy_map_p)
{
        vm_map_copy_t   target_copy_map;
        vm_map_entry_t  entry, target_entry;

        if (*target_copy_map_p != VM_MAP_COPY_NULL) {
                /* the caller already has a "target_copy_map": use it */
                return;
        }

        /* the caller wants us to create a new copy of "copy_map" */
        target_copy_map = vm_map_copy_allocate();
        target_copy_map->type = copy_map->type;
        assert(target_copy_map->type == VM_MAP_COPY_ENTRY_LIST);
        target_copy_map->offset = copy_map->offset;
        target_copy_map->size = copy_map->size;
        target_copy_map->cpy_hdr.page_shift = copy_map->cpy_hdr.page_shift;
        vm_map_store_init(&target_copy_map->cpy_hdr);
        for (entry = vm_map_copy_first_entry(copy_map);
            entry != vm_map_copy_to_entry(copy_map);
            entry = entry->vme_next) {
                target_entry = vm_map_copy_entry_create(target_copy_map, FALSE);
                vm_map_entry_copy_full(target_entry, entry);
                if (target_entry->is_sub_map) {
                        vm_map_reference(VME_SUBMAP(target_entry));
                } else {
                        vm_object_reference(VME_OBJECT(target_entry));
                }
                vm_map_copy_entry_link(
                        target_copy_map,
                        vm_map_copy_last_entry(target_copy_map),
                        target_entry);
        }
        entry = VM_MAP_ENTRY_NULL;
        *target_copy_map_p = target_copy_map;
}

void
vm_map_copy_trim(
        vm_map_copy_t   copy_map,
        int             new_page_shift,
        vm_map_offset_t trim_start,
        vm_map_offset_t trim_end);
void
vm_map_copy_trim(
        vm_map_copy_t   copy_map,
        int             new_page_shift,
        vm_map_offset_t trim_start,
        vm_map_offset_t trim_end)
{
        int             copy_page_shift;
        vm_map_entry_t  entry, next_entry;

        assert(copy_map->type == VM_MAP_COPY_ENTRY_LIST);
        assert(copy_map->cpy_hdr.nentries > 0);

        trim_start += vm_map_copy_first_entry(copy_map)->vme_start;
        trim_end += vm_map_copy_first_entry(copy_map)->vme_start;

        /* use the new page_shift to do the clipping */
        copy_page_shift = VM_MAP_COPY_PAGE_SHIFT(copy_map);
        copy_map->cpy_hdr.page_shift = new_page_shift;

        for (entry = vm_map_copy_first_entry(copy_map);
            entry != vm_map_copy_to_entry(copy_map);
            entry = next_entry) {
                next_entry = entry->vme_next;
                if (entry->vme_end <= trim_start) {
                        /* entry fully before trim range: skip */
                        continue;
                }
                if (entry->vme_start >= trim_end) {
                        /* entry fully after trim range: done */
                        break;
                }
                /* clip entry if needed */
                vm_map_copy_clip_start(copy_map, entry, trim_start);
                vm_map_copy_clip_end(copy_map, entry, trim_end);
                /* dispose of entry */
                copy_map->size -= entry->vme_end - entry->vme_start;
                vm_map_copy_entry_unlink(copy_map, entry);
                if (entry->is_sub_map) {
                        vm_map_deallocate(VME_SUBMAP(entry));
                } else {
                        vm_object_deallocate(VME_OBJECT(entry));
                }
                vm_map_copy_entry_dispose(copy_map, entry);
                entry = VM_MAP_ENTRY_NULL;
        }

        /* restore copy_map's original page_shift */
        copy_map->cpy_hdr.page_shift = copy_page_shift;
}

/*
 * Make any necessary adjustments to "copy_map" to allow it to be
 * mapped into "target_map".
 * If no changes were necessary, "target_copy_map" points to the
 * untouched "copy_map".
 * If changes are necessary, changes will be made to "target_copy_map".
 * If "target_copy_map" was NULL, we create a new "vm_map_copy_t" and
 * copy the original "copy_map" to it before applying the changes.
 * The caller should discard "target_copy_map" if it's not the same as
 * the original "copy_map".
 */
/* TODO4K: also adjust to sub-range in the copy_map -> add start&end? */
kern_return_t
vm_map_copy_adjust_to_target(
        vm_map_copy_t           src_copy_map,
        vm_map_offset_t         offset,
        vm_map_size_t           size,
        vm_map_t                target_map,
        boolean_t               copy,
        vm_map_copy_t           *target_copy_map_p,
        vm_map_offset_t         *overmap_start_p,
        vm_map_offset_t         *overmap_end_p,
        vm_map_offset_t         *trimmed_start_p)
{
        vm_map_copy_t           copy_map, target_copy_map;
        vm_map_size_t           target_size;
        vm_map_size_t           src_copy_map_size;
        vm_map_size_t           overmap_start, overmap_end;
        int                     misalignments;
        vm_map_entry_t          entry, target_entry;
        vm_map_offset_t         addr_adjustment;
        vm_map_offset_t         new_start, new_end;
        int                     copy_page_mask, target_page_mask;
        int                     copy_page_shift, target_page_shift;
        vm_map_offset_t         trimmed_end;

        /*
         * Assert that the vm_map_copy is coming from the right
         * zone and hasn't been forged
         */
        vm_map_copy_require(src_copy_map);
        assert(src_copy_map->type == VM_MAP_COPY_ENTRY_LIST);

        /*
         * Start working with "src_copy_map" but we'll switch
         * to "target_copy_map" as soon as we start making adjustments.
         */
        copy_map = src_copy_map;
        src_copy_map_size = src_copy_map->size;

        copy_page_shift = VM_MAP_COPY_PAGE_SHIFT(copy_map);
        copy_page_mask = VM_MAP_COPY_PAGE_MASK(copy_map);
        target_page_shift = VM_MAP_PAGE_SHIFT(target_map);
        target_page_mask = VM_MAP_PAGE_MASK(target_map);

        DEBUG4K_ADJUST("copy_map %p (%d offset 0x%llx size 0x%llx) target_map %p (%d) copy %d offset 0x%llx size 0x%llx target_copy_map %p...\n", copy_map, copy_page_shift, (uint64_t)copy_map->offset, (uint64_t)copy_map->size, target_map, target_page_shift, copy, (uint64_t)offset, (uint64_t)size, *target_copy_map_p);

        target_copy_map = *target_copy_map_p;
        if (target_copy_map != VM_MAP_COPY_NULL) {
                vm_map_copy_require(target_copy_map);
        }

        if (offset + size > copy_map->size) {
                DEBUG4K_ERROR("copy_map %p (%d->%d) copy_map->size 0x%llx offset 0x%llx size 0x%llx KERN_INVALID_ARGUMENT\n", copy_map, copy_page_shift, target_page_shift, (uint64_t)copy_map->size, (uint64_t)offset, (uint64_t)size);
                return KERN_INVALID_ARGUMENT;
        }

        /* trim the end */
        trimmed_end = 0;
        new_end = VM_MAP_ROUND_PAGE(offset + size, target_page_mask);
        if (new_end < copy_map->size) {
                trimmed_end = src_copy_map_size - new_end;
                DEBUG4K_ADJUST("copy_map %p (%d->%d) copy %d offset 0x%llx size 0x%llx target_copy_map %p... trim end from 0x%llx to 0x%llx\n", copy_map, copy_page_shift, target_page_shift, copy, (uint64_t)offset, (uint64_t)size, target_copy_map, (uint64_t)new_end, (uint64_t)copy_map->size);
                /* get "target_copy_map" if needed and adjust it */
                vm_map_copy_adjust_get_target_copy_map(copy_map,
                    &target_copy_map);
                copy_map = target_copy_map;
                vm_map_copy_trim(target_copy_map, target_page_shift,
                    new_end, copy_map->size);
        }

        /* trim the start */
        new_start = VM_MAP_TRUNC_PAGE(offset, target_page_mask);
        if (new_start != 0) {
                DEBUG4K_ADJUST("copy_map %p (%d->%d) copy %d offset 0x%llx size 0x%llx target_copy_map %p... trim start from 0x%llx to 0x%llx\n", copy_map, copy_page_shift, target_page_shift, copy, (uint64_t)offset, (uint64_t)size, target_copy_map, (uint64_t)0, (uint64_t)new_start);
                /* get "target_copy_map" if needed and adjust it */
                vm_map_copy_adjust_get_target_copy_map(copy_map,
                    &target_copy_map);
                copy_map = target_copy_map;
                vm_map_copy_trim(target_copy_map, target_page_shift,
                    0, new_start);
        }
        *trimmed_start_p = new_start;

        /* target_size starts with what's left after trimming */
        target_size = copy_map->size;
        assertf(target_size == src_copy_map_size - *trimmed_start_p - trimmed_end,
            "target_size 0x%llx src_copy_map_size 0x%llx trimmed_start 0x%llx trimmed_end 0x%llx\n",
            (uint64_t)target_size, (uint64_t)src_copy_map_size,
            (uint64_t)*trimmed_start_p, (uint64_t)trimmed_end);

        /* check for misalignments but don't adjust yet */
        misalignments = 0;
        overmap_start = 0;
        overmap_end = 0;
        if (copy_page_shift < target_page_shift) {
                /*
                 * Remapping from 4K to 16K: check the VM object alignments
                 * throughout the range.
                 * If the start and end of the range are mis-aligned, we can
                 * over-map to re-align, and adjust the "overmap" start/end
                 * and "target_size" of the range accordingly.
                 * If there is any mis-alignment within the range:
                 *     if "copy":
                 *         we can do immediate-copy instead of copy-on-write,
                 *     else:
                 *         no way to remap and share; fail.
                 */
                for (entry = vm_map_copy_first_entry(copy_map);
                    entry != vm_map_copy_to_entry(copy_map);
                    entry = entry->vme_next) {
                        vm_object_offset_t object_offset_start, object_offset_end;

                        object_offset_start = VME_OFFSET(entry);
                        object_offset_end = object_offset_start;
                        object_offset_end += entry->vme_end - entry->vme_start;
                        if (object_offset_start & target_page_mask) {
                                if (entry == vm_map_copy_first_entry(copy_map) && !copy) {
                                        overmap_start++;
                                } else {
                                        misalignments++;
                                }
                        }
                        if (object_offset_end & target_page_mask) {
                                if (entry->vme_next == vm_map_copy_to_entry(copy_map) && !copy) {
                                        overmap_end++;
                                } else {
                                        misalignments++;
                                }
                        }
                }
        }
        entry = VM_MAP_ENTRY_NULL;

        /* decide how to deal with misalignments */
        assert(overmap_start <= 1);
        assert(overmap_end <= 1);
        if (!overmap_start && !overmap_end && !misalignments) {
                /* copy_map is properly aligned for target_map ... */
                if (*trimmed_start_p) {
                        /* ... but we trimmed it, so still need to adjust */
                } else {
                        /* ... and we didn't trim anything: we're done */
                        if (target_copy_map == VM_MAP_COPY_NULL) {
                                target_copy_map = copy_map;
                        }
                        *target_copy_map_p = target_copy_map;
                        *overmap_start_p = 0;
                        *overmap_end_p = 0;
                        DEBUG4K_ADJUST("copy_map %p (%d offset 0x%llx size 0x%llx) target_map %p (%d) copy %d target_copy_map %p (%d offset 0x%llx size 0x%llx) -> trimmed 0x%llx overmap start 0x%llx end 0x%llx KERN_SUCCESS\n", copy_map, copy_page_shift, (uint64_t)copy_map->offset, (uint64_t)copy_map->size, target_map, target_page_shift, copy, *target_copy_map_p, VM_MAP_COPY_PAGE_SHIFT(*target_copy_map_p), (uint64_t)(*target_copy_map_p)->offset, (uint64_t)(*target_copy_map_p)->size, (uint64_t)*trimmed_start_p, (uint64_t)*overmap_start_p, (uint64_t)*overmap_end_p);
                        return KERN_SUCCESS;
                }
        } else if (misalignments && !copy) {
                /* can't "share" if misaligned */
                DEBUG4K_ADJUST("unsupported sharing\n");
#if MACH_ASSERT
                if (debug4k_panic_on_misaligned_sharing) {
                        panic("DEBUG4k %s:%d unsupported sharing\n", __FUNCTION__, __LINE__);
                }
#endif /* MACH_ASSERT */
                DEBUG4K_ADJUST("copy_map %p (%d) target_map %p (%d) copy %d target_copy_map %p -> KERN_NOT_SUPPORTED\n", copy_map, copy_page_shift, target_map, target_page_shift, copy, *target_copy_map_p);
                return KERN_NOT_SUPPORTED;
        } else {
                /* can't virtual-copy if misaligned (but can physical-copy) */
                DEBUG4K_ADJUST("mis-aligned copying\n");
        }

        /* get a "target_copy_map" if needed and switch to it */
        vm_map_copy_adjust_get_target_copy_map(copy_map, &target_copy_map);
        copy_map = target_copy_map;

        if (misalignments && copy) {
                vm_map_size_t target_copy_map_size;

                /*
                 * Can't do copy-on-write with misaligned mappings.
                 * Replace the mappings with a physical copy of the original
                 * mappings' contents.
                 */
                target_copy_map_size = target_copy_map->size;
                vm_map_copy_to_physcopy(target_copy_map, target_map);
                *target_copy_map_p = target_copy_map;
                *overmap_start_p = 0;
                *overmap_end_p = target_copy_map->size - target_copy_map_size;
                DEBUG4K_ADJUST("copy_map %p (%d offset 0x%llx size 0x%llx) target_map %p (%d) copy %d target_copy_map %p (%d offset 0x%llx size 0x%llx)-> trimmed 0x%llx overmap start 0x%llx end 0x%llx PHYSCOPY\n", copy_map, copy_page_shift, (uint64_t)copy_map->offset, (uint64_t)copy_map->size, target_map, target_page_shift, copy, *target_copy_map_p, VM_MAP_COPY_PAGE_SHIFT(*target_copy_map_p), (uint64_t)(*target_copy_map_p)->offset, (uint64_t)(*target_copy_map_p)->size, (uint64_t)*trimmed_start_p, (uint64_t)*overmap_start_p, (uint64_t)*overmap_end_p);
                return KERN_SUCCESS;
        }

        /* apply the adjustments */
        misalignments = 0;
        overmap_start = 0;
        overmap_end = 0;
        /* remove copy_map->offset, so that everything starts at offset 0 */
        addr_adjustment = copy_map->offset;
        /* also remove whatever we trimmed from the start */
        addr_adjustment += *trimmed_start_p;
        for (target_entry = vm_map_copy_first_entry(target_copy_map);
            target_entry != vm_map_copy_to_entry(target_copy_map);
            target_entry = target_entry->vme_next) {
                vm_object_offset_t object_offset_start, object_offset_end;

                DEBUG4K_ADJUST("copy %p (%d 0x%llx 0x%llx) entry %p [ 0x%llx 0x%llx ] object %p offset 0x%llx BEFORE\n", target_copy_map, VM_MAP_COPY_PAGE_SHIFT(target_copy_map), target_copy_map->offset, (uint64_t)target_copy_map->size, target_entry, (uint64_t)target_entry->vme_start, (uint64_t)target_entry->vme_end, VME_OBJECT(target_entry), VME_OFFSET(target_entry));
                object_offset_start = VME_OFFSET(target_entry);
                if (object_offset_start & target_page_mask) {
                        DEBUG4K_ADJUST("copy %p (%d 0x%llx 0x%llx) entry %p [ 0x%llx 0x%llx ] object %p offset 0x%llx misaligned at start\n", target_copy_map, VM_MAP_COPY_PAGE_SHIFT(target_copy_map), target_copy_map->offset, (uint64_t)target_copy_map->size, target_entry, (uint64_t)target_entry->vme_start, (uint64_t)target_entry->vme_end, VME_OBJECT(target_entry), VME_OFFSET(target_entry));
                        if (target_entry == vm_map_copy_first_entry(target_copy_map)) {
                                /*
                                 * start of 1st entry is mis-aligned:
                                 * re-adjust by over-mapping.
                                 */
                                overmap_start = object_offset_start - trunc_page_mask_64(object_offset_start, target_page_mask);
                                DEBUG4K_ADJUST("entry %p offset 0x%llx copy %d -> overmap_start 0x%llx\n", target_entry, VME_OFFSET(target_entry), copy, (uint64_t)overmap_start);
                                VME_OFFSET_SET(target_entry, VME_OFFSET(target_entry) - overmap_start);
                        } else {
                                misalignments++;
                                DEBUG4K_ADJUST("entry %p offset 0x%llx copy %d -> misalignments %d\n", target_entry, VME_OFFSET(target_entry), copy, misalignments);
                                assert(copy);
                        }
                }

                if (target_entry == vm_map_copy_first_entry(target_copy_map)) {
                        target_size += overmap_start;
                } else {
                        target_entry->vme_start += overmap_start;
                }
                target_entry->vme_end += overmap_start;

                object_offset_end = VME_OFFSET(target_entry) + target_entry->vme_end - target_entry->vme_start;
                if (object_offset_end & target_page_mask) {
                        DEBUG4K_ADJUST("copy %p (%d 0x%llx 0x%llx) entry %p [ 0x%llx 0x%llx ] object %p offset 0x%llx misaligned at end\n", target_copy_map, VM_MAP_COPY_PAGE_SHIFT(target_copy_map), target_copy_map->offset, (uint64_t)target_copy_map->size, target_entry, (uint64_t)target_entry->vme_start, (uint64_t)target_entry->vme_end, VME_OBJECT(target_entry), VME_OFFSET(target_entry));
                        if (target_entry->vme_next == vm_map_copy_to_entry(target_copy_map)) {
                                /*
                                 * end of last entry is mis-aligned: re-adjust by over-mapping.
                                 */
                                overmap_end = round_page_mask_64(object_offset_end, target_page_mask) - object_offset_end;
                                DEBUG4K_ADJUST("entry %p offset 0x%llx copy %d -> overmap_end 0x%llx\n", target_entry, VME_OFFSET(target_entry), copy, (uint64_t)overmap_end);
                                target_entry->vme_end += overmap_end;
                                target_size += overmap_end;
                        } else {
                                misalignments++;
                                DEBUG4K_ADJUST("entry %p offset 0x%llx copy %d -> misalignments %d\n", target_entry, VME_OFFSET(target_entry), copy, misalignments);
                                assert(copy);
                        }
                }
                target_entry->vme_start -= addr_adjustment;
                target_entry->vme_end -= addr_adjustment;
                DEBUG4K_ADJUST("copy %p (%d 0x%llx 0x%llx) entry %p [ 0x%llx 0x%llx ] object %p offset 0x%llx AFTER\n", target_copy_map, VM_MAP_COPY_PAGE_SHIFT(target_copy_map), target_copy_map->offset, (uint64_t)target_copy_map->size, target_entry, (uint64_t)target_entry->vme_start, (uint64_t)target_entry->vme_end, VME_OBJECT(target_entry), VME_OFFSET(target_entry));
        }

        target_copy_map->size = target_size;
        target_copy_map->offset += overmap_start;
        target_copy_map->offset -= addr_adjustment;
        target_copy_map->cpy_hdr.page_shift = target_page_shift;

//      assert(VM_MAP_PAGE_ALIGNED(target_copy_map->size, target_page_mask));
//      assert(VM_MAP_PAGE_ALIGNED(target_copy_map->offset, FOURK_PAGE_MASK));
        assert(overmap_start < VM_MAP_PAGE_SIZE(target_map));
        assert(overmap_end < VM_MAP_PAGE_SIZE(target_map));

        *target_copy_map_p = target_copy_map;
        *overmap_start_p = overmap_start;
        *overmap_end_p = overmap_end;

        DEBUG4K_ADJUST("copy_map %p (%d offset 0x%llx size 0x%llx) target_map %p (%d) copy %d target_copy_map %p (%d offset 0x%llx size 0x%llx) -> trimmed 0x%llx overmap start 0x%llx end 0x%llx KERN_SUCCESS\n", copy_map, copy_page_shift, (uint64_t)copy_map->offset, (uint64_t)copy_map->size, target_map, target_page_shift, copy, *target_copy_map_p, VM_MAP_COPY_PAGE_SHIFT(*target_copy_map_p), (uint64_t)(*target_copy_map_p)->offset, (uint64_t)(*target_copy_map_p)->size, (uint64_t)*trimmed_start_p, (uint64_t)*overmap_start_p, (uint64_t)*overmap_end_p);
        return KERN_SUCCESS;
}

kern_return_t
vm_map_range_physical_size(
        vm_map_t         map,
        vm_map_address_t start,
        mach_vm_size_t   size,
        mach_vm_size_t * phys_size)
{
        kern_return_t   kr;
        vm_map_copy_t   copy_map, target_copy_map;
        vm_map_offset_t adjusted_start, adjusted_end;
        vm_map_size_t   adjusted_size;
        vm_prot_t       cur_prot, max_prot;
        vm_map_offset_t overmap_start, overmap_end, trimmed_start;
        vm_map_kernel_flags_t vmk_flags;

        adjusted_start = vm_map_trunc_page(start, VM_MAP_PAGE_MASK(map));
        adjusted_end = vm_map_round_page(start + size, VM_MAP_PAGE_MASK(map));
        adjusted_size = adjusted_end - adjusted_start;
        *phys_size = adjusted_size;
        if (VM_MAP_PAGE_SIZE(map) == PAGE_SIZE) {
                return KERN_SUCCESS;
        }
        if (start == 0) {
                adjusted_start = vm_map_trunc_page(start, PAGE_MASK);
                adjusted_end = vm_map_round_page(start + size, PAGE_MASK);
                adjusted_size = adjusted_end - adjusted_start;
                *phys_size = adjusted_size;
                return KERN_SUCCESS;
        }
        if (adjusted_size == 0) {
                DEBUG4K_SHARE("map %p start 0x%llx size 0x%llx adjusted 0x%llx -> phys_size 0!\n", map, (uint64_t)start, (uint64_t)size, (uint64_t)adjusted_size);
                *phys_size = 0;
                return KERN_SUCCESS;
        }

        vmk_flags = VM_MAP_KERNEL_FLAGS_NONE;
        vmk_flags.vmkf_copy_pageable = TRUE;
        vmk_flags.vmkf_copy_same_map = TRUE;
        assert(adjusted_size != 0);
        kr = vm_map_copy_extract(map, adjusted_start, adjusted_size,
            VM_PROT_NONE, /* required_protection: no check here */
            FALSE /* copy */,
            &copy_map,
            &cur_prot, &max_prot, VM_INHERIT_DEFAULT,
            vmk_flags);
        if (kr != KERN_SUCCESS) {
                DEBUG4K_ERROR("map %p start 0x%llx 0x%llx size 0x%llx 0x%llx kr 0x%x\n", map, (uint64_t)start, (uint64_t)adjusted_start, size, (uint64_t)adjusted_size, kr);
                //assert(0);
                *phys_size = 0;
                return kr;
        }
        assert(copy_map != VM_MAP_COPY_NULL);
        target_copy_map = copy_map;
        DEBUG4K_ADJUST("adjusting...\n");
        kr = vm_map_copy_adjust_to_target(
                copy_map,
                start - adjusted_start, /* offset */
                size, /* size */
                kernel_map,
                FALSE,                          /* copy */
                &target_copy_map,
                &overmap_start,
                &overmap_end,
                &trimmed_start);
        if (kr == KERN_SUCCESS) {
                if (target_copy_map->size != *phys_size) {
                        DEBUG4K_ADJUST("map %p (%d) start 0x%llx size 0x%llx adjusted_start 0x%llx adjusted_end 0x%llx overmap_start 0x%llx overmap_end 0x%llx trimmed_start 0x%llx phys_size 0x%llx -> 0x%llx\n", map, VM_MAP_PAGE_SHIFT(map), (uint64_t)start, (uint64_t)size, (uint64_t)adjusted_start, (uint64_t)adjusted_end, (uint64_t)overmap_start, (uint64_t)overmap_end, (uint64_t)trimmed_start, (uint64_t)*phys_size, (uint64_t)target_copy_map->size);
                }
                *phys_size = target_copy_map->size;
        } else {
                DEBUG4K_ERROR("map %p start 0x%llx 0x%llx size 0x%llx 0x%llx kr 0x%x\n", map, (uint64_t)start, (uint64_t)adjusted_start, size, (uint64_t)adjusted_size, kr);
                //assert(0);
                *phys_size = 0;
        }
        vm_map_copy_discard(copy_map);
        copy_map = VM_MAP_COPY_NULL;

        return kr;
}


kern_return_t
memory_entry_check_for_adjustment(
        vm_map_t                        src_map,
        ipc_port_t                      port,
        vm_map_offset_t         *overmap_start,
        vm_map_offset_t         *overmap_end)
{
        kern_return_t kr = KERN_SUCCESS;
        vm_map_copy_t copy_map = VM_MAP_COPY_NULL, target_copy_map = VM_MAP_COPY_NULL;

        assert(port);
        assertf(ip_kotype(port) == IKOT_NAMED_ENTRY, "Port Type expected: %d...received:%d\n", IKOT_NAMED_ENTRY, ip_kotype(port));

        vm_named_entry_t        named_entry;

        named_entry = (vm_named_entry_t) port->ip_kobject;
        named_entry_lock(named_entry);
        copy_map = named_entry->backing.copy;
        target_copy_map = copy_map;

        if (src_map && VM_MAP_PAGE_SHIFT(src_map) < PAGE_SHIFT) {
                vm_map_offset_t trimmed_start;

                trimmed_start = 0;
                DEBUG4K_ADJUST("adjusting...\n");
                kr = vm_map_copy_adjust_to_target(
                        copy_map,
                        0, /* offset */
                        copy_map->size, /* size */
                        src_map,
                        FALSE, /* copy */
                        &target_copy_map,
                        overmap_start,
                        overmap_end,
                        &trimmed_start);
                assert(trimmed_start == 0);
        }
        named_entry_unlock(named_entry);

        return kr;
}


/*
 *      Routine:        vm_remap
 *
 *                      Map portion of a task's address space.
 *                      Mapped region must not overlap more than
 *                      one vm memory object. Protections and
 *                      inheritance attributes remain the same
 *                      as in the original task and are out parameters.
 *                      Source and Target task can be identical
 *                      Other attributes are identical as for vm_map()
 */
kern_return_t
vm_map_remap(
        vm_map_t                target_map,
        vm_map_address_t        *address,
        vm_map_size_t           size,
        vm_map_offset_t         mask,
        int                     flags,
        vm_map_kernel_flags_t   vmk_flags,
        vm_tag_t                tag,
        vm_map_t                src_map,
        vm_map_offset_t         memory_address,
        boolean_t               copy,
        vm_prot_t               *cur_protection,
        vm_prot_t               *max_protection,
        vm_inherit_t            inheritance)
{
        kern_return_t           result;
        vm_map_entry_t          entry;
        vm_map_entry_t          insp_entry = VM_MAP_ENTRY_NULL;
        vm_map_entry_t          new_entry;
        vm_map_copy_t           copy_map;
        vm_map_offset_t         offset_in_mapping;
        vm_map_size_t           target_size = 0;
        vm_map_size_t           src_page_mask, target_page_mask;
        vm_map_offset_t         overmap_start, overmap_end, trimmed_start;
        vm_map_offset_t         initial_memory_address;
        vm_map_size_t           initial_size;

        if (target_map == VM_MAP_NULL) {
                return KERN_INVALID_ARGUMENT;
        }

        initial_memory_address = memory_address;
        initial_size = size;
        src_page_mask = VM_MAP_PAGE_MASK(src_map);
        target_page_mask = VM_MAP_PAGE_MASK(target_map);

        switch (inheritance) {
        case VM_INHERIT_NONE:
        case VM_INHERIT_COPY:
        case VM_INHERIT_SHARE:
                if (size != 0 && src_map != VM_MAP_NULL) {
                        break;
                }
                OS_FALLTHROUGH;
        default:
                return KERN_INVALID_ARGUMENT;
        }

        if (src_page_mask != target_page_mask) {
                if (copy) {
                        DEBUG4K_COPY("src_map %p pgsz 0x%x addr 0x%llx size 0x%llx copy %d -> target_map %p pgsz 0x%x\n", src_map, VM_MAP_PAGE_SIZE(src_map), (uint64_t)memory_address, (uint64_t)size, copy, target_map, VM_MAP_PAGE_SIZE(target_map));
                } else {
                        DEBUG4K_SHARE("src_map %p pgsz 0x%x addr 0x%llx size 0x%llx copy %d -> target_map %p pgsz 0x%x\n", src_map, VM_MAP_PAGE_SIZE(src_map), (uint64_t)memory_address, (uint64_t)size, copy, target_map, VM_MAP_PAGE_SIZE(target_map));
                }
        }

        /*
         * If the user is requesting that we return the address of the
         * first byte of the data (rather than the base of the page),
         * then we use different rounding semantics: specifically,
         * we assume that (memory_address, size) describes a region
         * all of whose pages we must cover, rather than a base to be truncated
         * down and a size to be added to that base.  So we figure out
         * the highest page that the requested region includes and make
         * sure that the size will cover it.
         *
         * The key example we're worried about it is of the form:
         *
         *              memory_address = 0x1ff0, size = 0x20
         *
         * With the old semantics, we round down the memory_address to 0x1000
         * and round up the size to 0x1000, resulting in our covering *only*
         * page 0x1000.  With the new semantics, we'd realize that the region covers
         * 0x1ff0-0x2010, and compute a size of 0x2000.  Thus, we cover both page
         * 0x1000 and page 0x2000 in the region we remap.
         */
        if ((flags & VM_FLAGS_RETURN_DATA_ADDR) != 0) {
                vm_map_offset_t range_start, range_end;

                range_start = vm_map_trunc_page(memory_address, src_page_mask);
                range_end = vm_map_round_page(memory_address + size, src_page_mask);
                memory_address = range_start;
                size = range_end - range_start;
                offset_in_mapping = initial_memory_address - memory_address;
        } else {
                /*
                 * IMPORTANT:
                 * This legacy code path is broken: for the range mentioned
                 * above [ memory_address = 0x1ff0,size = 0x20 ], which spans
                 * two 4k pages, it yields [ memory_address = 0x1000,
                 * size = 0x1000 ], which covers only the first 4k page.
                 * BUT some code unfortunately depends on this bug, so we
                 * can't fix it without breaking something.
                 * New code should get automatically opted in the new
                 * behavior with the new VM_FLAGS_RETURN_DATA_ADDR flags.
                 */
                offset_in_mapping = 0;
                memory_address = vm_map_trunc_page(memory_address, src_page_mask);
                size = vm_map_round_page(size, src_page_mask);
                initial_memory_address = memory_address;
                initial_size = size;
        }


        if (size == 0) {
                return KERN_INVALID_ARGUMENT;
        }

        if (flags & VM_FLAGS_RESILIENT_MEDIA) {
                /* must be copy-on-write to be "media resilient" */
                if (!copy) {
                        return KERN_INVALID_ARGUMENT;
                }
        }

        vmk_flags.vmkf_copy_pageable = target_map->hdr.entries_pageable;
        vmk_flags.vmkf_copy_same_map = (src_map == target_map);

        assert(size != 0);
        result = vm_map_copy_extract(src_map,
            memory_address,
            size,
            VM_PROT_NONE, /* required_protection: no check here */
            copy, &copy_map,
            cur_protection,
            max_protection,
            inheritance,
            vmk_flags);
        if (result != KERN_SUCCESS) {
                return result;
        }
        assert(copy_map != VM_MAP_COPY_NULL);

        overmap_start = 0;
        overmap_end = 0;
        trimmed_start = 0;
        target_size = size;
        if (src_page_mask != target_page_mask) {
                vm_map_copy_t target_copy_map;

                target_copy_map = copy_map; /* can modify "copy_map" itself */
                DEBUG4K_ADJUST("adjusting...\n");
                result = vm_map_copy_adjust_to_target(
                        copy_map,
                        offset_in_mapping, /* offset */
                        initial_size,
                        target_map,
                        copy,
                        &target_copy_map,
                        &overmap_start,
                        &overmap_end,
                        &trimmed_start);
                if (result != KERN_SUCCESS) {
                        DEBUG4K_COPY("failed to adjust 0x%x\n", result);
                        vm_map_copy_discard(copy_map);
                        return result;
                }
                if (trimmed_start == 0) {
                        /* nothing trimmed: no adjustment needed */
                } else if (trimmed_start >= offset_in_mapping) {
                        /* trimmed more than offset_in_mapping: nothing left */
                        assert(overmap_start == 0);
                        assert(overmap_end == 0);
                        offset_in_mapping = 0;
                } else {
                        /* trimmed some of offset_in_mapping: adjust */
                        assert(overmap_start == 0);
                        assert(overmap_end == 0);
                        offset_in_mapping -= trimmed_start;
                }
                offset_in_mapping += overmap_start;
                target_size = target_copy_map->size;
        }

        /*
         * Allocate/check a range of free virtual address
         * space for the target
         */
        *address = vm_map_trunc_page(*address, target_page_mask);
        vm_map_lock(target_map);
        target_size = vm_map_round_page(target_size, target_page_mask);
        result = vm_map_remap_range_allocate(target_map, address,
            target_size,
            mask, flags, vmk_flags, tag,
            &insp_entry);

        for (entry = vm_map_copy_first_entry(copy_map);
            entry != vm_map_copy_to_entry(copy_map);
            entry = new_entry) {
                new_entry = entry->vme_next;
                vm_map_copy_entry_unlink(copy_map, entry);
                if (result == KERN_SUCCESS) {
                        if (flags & VM_FLAGS_RESILIENT_CODESIGN) {
                                /* no codesigning -> read-only access */
                                entry->max_protection = VM_PROT_READ;
                                entry->protection = VM_PROT_READ;
                                entry->vme_resilient_codesign = TRUE;
                        }
                        entry->vme_start += *address;
                        entry->vme_end += *address;
                        assert(!entry->map_aligned);
                        if ((flags & VM_FLAGS_RESILIENT_MEDIA) &&
                            !entry->is_sub_map &&
                            (VME_OBJECT(entry) == VM_OBJECT_NULL ||
                            VME_OBJECT(entry)->internal)) {
                                entry->vme_resilient_media = TRUE;
                        }
                        assert(VM_MAP_PAGE_ALIGNED(entry->vme_start, MIN(target_page_mask, PAGE_MASK)));
                        assert(VM_MAP_PAGE_ALIGNED(entry->vme_end, MIN(target_page_mask, PAGE_MASK)));
                        assert(VM_MAP_PAGE_ALIGNED(VME_OFFSET(entry), MIN(target_page_mask, PAGE_MASK)));
                        vm_map_store_entry_link(target_map, insp_entry, entry,
                            vmk_flags);
                        insp_entry = entry;
                } else {
                        if (!entry->is_sub_map) {
                                vm_object_deallocate(VME_OBJECT(entry));
                        } else {
                                vm_map_deallocate(VME_SUBMAP(entry));
                        }
                        vm_map_copy_entry_dispose(copy_map, entry);
                }
        }

        if (flags & VM_FLAGS_RESILIENT_CODESIGN) {
                *cur_protection = VM_PROT_READ;
                *max_protection = VM_PROT_READ;
        }

        if (target_map->disable_vmentry_reuse == TRUE) {
                assert(!target_map->is_nested_map);
                if (target_map->highest_entry_end < insp_entry->vme_end) {
                        target_map->highest_entry_end = insp_entry->vme_end;
                }
        }

        if (result == KERN_SUCCESS) {
                target_map->size += target_size;
                SAVE_HINT_MAP_WRITE(target_map, insp_entry);

        }
        vm_map_unlock(target_map);

        if (result == KERN_SUCCESS && target_map->wiring_required) {
                result = vm_map_wire_kernel(target_map, *address,
                    *address + size, *cur_protection, VM_KERN_MEMORY_MLOCK,
                    TRUE);
        }

        /*
         * If requested, return the address of the data pointed to by the
         * request, rather than the base of the resulting page.
         */
        if ((flags & VM_FLAGS_RETURN_DATA_ADDR) != 0) {
                *address += offset_in_mapping;
        }

        if (src_page_mask != target_page_mask) {
                DEBUG4K_SHARE("vm_remap(%p 0x%llx 0x%llx copy=%d-> %p 0x%llx 0x%llx  result=0x%x\n", src_map, (uint64_t)memory_address, (uint64_t)size, copy, target_map, (uint64_t)*address, (uint64_t)offset_in_mapping, result);
        }
        vm_map_copy_discard(copy_map);
        copy_map = VM_MAP_COPY_NULL;

        return result;
}

/*
 *      Routine:        vm_map_remap_range_allocate
 *
 *      Description:
 *              Allocate a range in the specified virtual address map.
 *              returns the address and the map entry just before the allocated
 *              range
 *
 *      Map must be locked.
 */

static kern_return_t
vm_map_remap_range_allocate(
        vm_map_t                map,
        vm_map_address_t        *address,       /* IN/OUT */
        vm_map_size_t           size,
        vm_map_offset_t         mask,
        int                     flags,
        vm_map_kernel_flags_t   vmk_flags,
        __unused vm_tag_t       tag,
        vm_map_entry_t          *map_entry)     /* OUT */
{
        vm_map_entry_t  entry;
        vm_map_offset_t start;
        vm_map_offset_t end;
        vm_map_offset_t desired_empty_end;
        kern_return_t   kr;
        vm_map_entry_t          hole_entry;

StartAgain:;

        start = *address;

        if (flags & VM_FLAGS_ANYWHERE) {
                if (flags & VM_FLAGS_RANDOM_ADDR) {
                        /*
                         * Get a random start address.
                         */
                        kr = vm_map_random_address_for_size(map, address, size);
                        if (kr != KERN_SUCCESS) {
                                return kr;
                        }
                        start = *address;
                }

                /*
                 *      Calculate the first possible address.
                 */

                if (start < map->min_offset) {
                        start = map->min_offset;
                }
                if (start > map->max_offset) {
                        return KERN_NO_SPACE;
                }

                /*
                 *      Look for the first possible address;
                 *      if there's already something at this
                 *      address, we have to start after it.
                 */

                if (map->disable_vmentry_reuse == TRUE) {
                        VM_MAP_HIGHEST_ENTRY(map, entry, start);
                } else {
                        if (map->holelistenabled) {
                                hole_entry = CAST_TO_VM_MAP_ENTRY(map->holes_list);

                                if (hole_entry == NULL) {
                                        /*
                                         * No more space in the map?
                                         */
                                        return KERN_NO_SPACE;
                                } else {
                                        boolean_t found_hole = FALSE;

                                        do {
                                                if (hole_entry->vme_start >= start) {
                                                        start = hole_entry->vme_start;
                                                        found_hole = TRUE;
                                                        break;
                                                }

                                                if (hole_entry->vme_end > start) {
                                                        found_hole = TRUE;
                                                        break;
                                                }
                                                hole_entry = hole_entry->vme_next;
                                        } while (hole_entry != CAST_TO_VM_MAP_ENTRY(map->holes_list));

                                        if (found_hole == FALSE) {
                                                return KERN_NO_SPACE;
                                        }

                                        entry = hole_entry;
                                }
                        } else {
                                assert(first_free_is_valid(map));
                                if (start == map->min_offset) {
                                        if ((entry = map->first_free) != vm_map_to_entry(map)) {
                                                start = entry->vme_end;
                                        }
                                } else {
                                        vm_map_entry_t  tmp_entry;
                                        if (vm_map_lookup_entry(map, start, &tmp_entry)) {
                                                start = tmp_entry->vme_end;
                                        }
                                        entry = tmp_entry;
                                }
                        }
                        start = vm_map_round_page(start,
                            VM_MAP_PAGE_MASK(map));
                }

                /*
                 *      In any case, the "entry" always precedes
                 *      the proposed new region throughout the
                 *      loop:
                 */

                while (TRUE) {
                        vm_map_entry_t  next;

                        /*
                         *      Find the end of the proposed new region.
                         *      Be sure we didn't go beyond the end, or
                         *      wrap around the address.
                         */

                        end = ((start + mask) & ~mask);
                        end = vm_map_round_page(end,
                            VM_MAP_PAGE_MASK(map));
                        if (end < start) {
                                return KERN_NO_SPACE;
                        }
                        start = end;
                        end += size;

                        /* We want an entire page of empty space, but don't increase the allocation size. */
                        desired_empty_end = vm_map_round_page(end, VM_MAP_PAGE_MASK(map));

                        if ((desired_empty_end > map->max_offset) || (desired_empty_end < start)) {
                                if (map->wait_for_space) {
                                        if (size <= (map->max_offset -
                                            map->min_offset)) {
                                                assert_wait((event_t) map, THREAD_INTERRUPTIBLE);
                                                vm_map_unlock(map);
                                                thread_block(THREAD_CONTINUE_NULL);
                                                vm_map_lock(map);
                                                goto StartAgain;
                                        }
                                }

                                return KERN_NO_SPACE;
                        }

                        next = entry->vme_next;

                        if (map->holelistenabled) {
                                if (entry->vme_end >= desired_empty_end) {
                                        break;
                                }
                        } else {
                                /*
                                 *      If there are no more entries, we must win.
                                 *
                                 *      OR
                                 *
                                 *      If there is another entry, it must be
                                 *      after the end of the potential new region.
                                 */

                                if (next == vm_map_to_entry(map)) {
                                        break;
                                }

                                if (next->vme_start >= desired_empty_end) {
                                        break;
                                }
                        }

                        /*
                         *      Didn't fit -- move to the next entry.
                         */

                        entry = next;

                        if (map->holelistenabled) {
                                if (entry == CAST_TO_VM_MAP_ENTRY(map->holes_list)) {
                                        /*
                                         * Wrapped around
                                         */
                                        return KERN_NO_SPACE;
                                }
                                start = entry->vme_start;
                        } else {
                                start = entry->vme_end;
                        }
                }

                if (map->holelistenabled) {
                        if (vm_map_lookup_entry(map, entry->vme_start, &entry)) {
                                panic("Found an existing entry (%p) instead of potential hole at address: 0x%llx.\n", entry, (unsigned long long)entry->vme_start);
                        }
                }

                *address = start;
        } else {
                vm_map_entry_t          temp_entry;

                /*
                 *      Verify that:
                 *              the address doesn't itself violate
                 *              the mask requirement.
                 */

                if ((start & mask) != 0) {
                        return KERN_NO_SPACE;
                }


                /*
                 *      ...     the address is within bounds
                 */

                end = start + size;

                if ((start < map->min_offset) ||
                    (end > map->max_offset) ||
                    (start >= end)) {
                        return KERN_INVALID_ADDRESS;
                }

                /*
                 * If we're asked to overwrite whatever was mapped in that
                 * range, first deallocate that range.
                 */
                if (flags & VM_FLAGS_OVERWRITE) {
                        vm_map_t zap_map;
                        int remove_flags = VM_MAP_REMOVE_SAVE_ENTRIES | VM_MAP_REMOVE_NO_MAP_ALIGN;

                        /*
                         * We use a "zap_map" to avoid having to unlock
                         * the "map" in vm_map_delete(), which would compromise
                         * the atomicity of the "deallocate" and then "remap"
                         * combination.
                         */
                        zap_map = vm_map_create(PMAP_NULL,
                            start,
                            end,
                            map->hdr.entries_pageable);
                        if (zap_map == VM_MAP_NULL) {
                                return KERN_RESOURCE_SHORTAGE;
                        }
                        vm_map_set_page_shift(zap_map, VM_MAP_PAGE_SHIFT(map));
                        vm_map_disable_hole_optimization(zap_map);

                        if (vmk_flags.vmkf_overwrite_immutable) {
                                remove_flags |= VM_MAP_REMOVE_IMMUTABLE;
                        }
                        kr = vm_map_delete(map, start, end,
                            remove_flags,
                            zap_map);
                        if (kr == KERN_SUCCESS) {
                                vm_map_destroy(zap_map,
                                    VM_MAP_REMOVE_NO_PMAP_CLEANUP);
                                zap_map = VM_MAP_NULL;
                        }
                }

                /*
                 *      ...     the starting address isn't allocated
                 */

                if (vm_map_lookup_entry(map, start, &temp_entry)) {
                        return KERN_NO_SPACE;
                }

                entry = temp_entry;

                /*
                 *      ...     the next region doesn't overlap the
                 *              end point.
                 */

                if ((entry->vme_next != vm_map_to_entry(map)) &&
                    (entry->vme_next->vme_start < end)) {
                        return KERN_NO_SPACE;
                }
        }
        *map_entry = entry;
        return KERN_SUCCESS;
}

/*
 *      vm_map_switch:
 *
 *      Set the address map for the current thread to the specified map
 */

vm_map_t
vm_map_switch(
        vm_map_t        map)
{
        int             mycpu;
        thread_t        thread = current_thread();
        vm_map_t        oldmap = thread->map;

        mp_disable_preemption();
        mycpu = cpu_number();

        /*
         *      Deactivate the current map and activate the requested map
         */
        PMAP_SWITCH_USER(thread, map, mycpu);

        mp_enable_preemption();
        return oldmap;
}


/*
 *      Routine:        vm_map_write_user
 *
 *      Description:
 *              Copy out data from a kernel space into space in the
 *              destination map. The space must already exist in the
 *              destination map.
 *              NOTE:  This routine should only be called by threads
 *              which can block on a page fault. i.e. kernel mode user
 *              threads.
 *
 */
kern_return_t
vm_map_write_user(
        vm_map_t                map,
        void                    *src_p,
        vm_map_address_t        dst_addr,
        vm_size_t               size)
{
        kern_return_t   kr = KERN_SUCCESS;

        if (current_map() == map) {
                if (copyout(src_p, dst_addr, size)) {
                        kr = KERN_INVALID_ADDRESS;
                }
        } else {
                vm_map_t        oldmap;

                /* take on the identity of the target map while doing */
                /* the transfer */

                vm_map_reference(map);
                oldmap = vm_map_switch(map);
                if (copyout(src_p, dst_addr, size)) {
                        kr = KERN_INVALID_ADDRESS;
                }
                vm_map_switch(oldmap);
                vm_map_deallocate(map);
        }
        return kr;
}

/*
 *      Routine:        vm_map_read_user
 *
 *      Description:
 *              Copy in data from a user space source map into the
 *              kernel map. The space must already exist in the
 *              kernel map.
 *              NOTE:  This routine should only be called by threads
 *              which can block on a page fault. i.e. kernel mode user
 *              threads.
 *
 */
kern_return_t
vm_map_read_user(
        vm_map_t                map,
        vm_map_address_t        src_addr,
        void                    *dst_p,
        vm_size_t               size)
{
        kern_return_t   kr = KERN_SUCCESS;

        if (current_map() == map) {
                if (copyin(src_addr, dst_p, size)) {
                        kr = KERN_INVALID_ADDRESS;
                }
        } else {
                vm_map_t        oldmap;

                /* take on the identity of the target map while doing */
                /* the transfer */

                vm_map_reference(map);
                oldmap = vm_map_switch(map);
                if (copyin(src_addr, dst_p, size)) {
                        kr = KERN_INVALID_ADDRESS;
                }
                vm_map_switch(oldmap);
                vm_map_deallocate(map);
        }
        return kr;
}


/*
 *      vm_map_check_protection:
 *
 *      Assert that the target map allows the specified
 *      privilege on the entire address region given.
 *      The entire region must be allocated.
 */
boolean_t
vm_map_check_protection(vm_map_t map, vm_map_offset_t start,
    vm_map_offset_t end, vm_prot_t protection)
{
        vm_map_entry_t entry;
        vm_map_entry_t tmp_entry;

        vm_map_lock(map);

        if (start < vm_map_min(map) || end > vm_map_max(map) || start > end) {
                vm_map_unlock(map);
                return FALSE;
        }

        if (!vm_map_lookup_entry(map, start, &tmp_entry)) {
                vm_map_unlock(map);
                return FALSE;
        }

        entry = tmp_entry;

        while (start < end) {
                if (entry == vm_map_to_entry(map)) {
                        vm_map_unlock(map);
                        return FALSE;
                }

                /*
                 *      No holes allowed!
                 */

                if (start < entry->vme_start) {
                        vm_map_unlock(map);
                        return FALSE;
                }

                /*
                 * Check protection associated with entry.
                 */

                if ((entry->protection & protection) != protection) {
                        vm_map_unlock(map);
                        return FALSE;
                }

                /* go to next entry */

                start = entry->vme_end;
                entry = entry->vme_next;
        }
        vm_map_unlock(map);
        return TRUE;
}

kern_return_t
vm_map_purgable_control(
        vm_map_t                map,
        vm_map_offset_t         address,
        vm_purgable_t           control,
        int                     *state)
{
        vm_map_entry_t          entry;
        vm_object_t             object;
        kern_return_t           kr;
        boolean_t               was_nonvolatile;

        /*
         * Vet all the input parameters and current type and state of the
         * underlaying object.  Return with an error if anything is amiss.
         */
        if (map == VM_MAP_NULL) {
                return KERN_INVALID_ARGUMENT;
        }

        if (control != VM_PURGABLE_SET_STATE &&
            control != VM_PURGABLE_GET_STATE &&
            control != VM_PURGABLE_PURGE_ALL &&
            control != VM_PURGABLE_SET_STATE_FROM_KERNEL) {
                return KERN_INVALID_ARGUMENT;
        }

        if (control == VM_PURGABLE_PURGE_ALL) {
                vm_purgeable_object_purge_all();
                return KERN_SUCCESS;
        }

        if ((control == VM_PURGABLE_SET_STATE ||
            control == VM_PURGABLE_SET_STATE_FROM_KERNEL) &&
            (((*state & ~(VM_PURGABLE_ALL_MASKS)) != 0) ||
            ((*state & VM_PURGABLE_STATE_MASK) > VM_PURGABLE_STATE_MASK))) {
                return KERN_INVALID_ARGUMENT;
        }

        vm_map_lock_read(map);

        if (!vm_map_lookup_entry(map, address, &entry) || entry->is_sub_map) {
                /*
                 * Must pass a valid non-submap address.
                 */
                vm_map_unlock_read(map);
                return KERN_INVALID_ADDRESS;
        }

        if ((entry->protection & VM_PROT_WRITE) == 0) {
                /*
                 * Can't apply purgable controls to something you can't write.
                 */
                vm_map_unlock_read(map);
                return KERN_PROTECTION_FAILURE;
        }

        object = VME_OBJECT(entry);
        if (object == VM_OBJECT_NULL ||
            object->purgable == VM_PURGABLE_DENY) {
                /*
                 * Object must already be present and be purgeable.
                 */
                vm_map_unlock_read(map);
                return KERN_INVALID_ARGUMENT;
        }

        vm_object_lock(object);

#if 00
        if (VME_OFFSET(entry) != 0 ||
            entry->vme_end - entry->vme_start != object->vo_size) {
                /*
                 * Can only apply purgable controls to the whole (existing)
                 * object at once.
                 */
                vm_map_unlock_read(map);
                vm_object_unlock(object);
                return KERN_INVALID_ARGUMENT;
        }
#endif

        assert(!entry->is_sub_map);
        assert(!entry->use_pmap); /* purgeable has its own accounting */

        vm_map_unlock_read(map);

        was_nonvolatile = (object->purgable == VM_PURGABLE_NONVOLATILE);

        kr = vm_object_purgable_control(object, control, state);

        if (was_nonvolatile &&
            object->purgable != VM_PURGABLE_NONVOLATILE &&
            map->pmap == kernel_pmap) {
#if DEBUG
                object->vo_purgeable_volatilizer = kernel_task;
#endif /* DEBUG */
        }

        vm_object_unlock(object);

        return kr;
}

void
vm_map_footprint_query_page_info(
        vm_map_t        map,
        vm_map_entry_t  map_entry,
        vm_map_offset_t curr_s_offset,
        int             *disposition_p)
{
        int             pmap_disp;
        vm_object_t     object;
        int             disposition;
        int             effective_page_size;

        vm_map_lock_assert_held(map);
        assert(!map->has_corpse_footprint);
        assert(curr_s_offset >= map_entry->vme_start);
        assert(curr_s_offset < map_entry->vme_end);

        object = VME_OBJECT(map_entry);
        if (object == VM_OBJECT_NULL) {
                *disposition_p = 0;
                return;
        }

        effective_page_size = MIN(PAGE_SIZE, VM_MAP_PAGE_SIZE(map));

        pmap_disp = 0;
        if (object == VM_OBJECT_NULL) {
                /* nothing mapped here: no need to ask */
                *disposition_p = 0;
                return;
        } else if (map_entry->is_sub_map &&
            !map_entry->use_pmap) {
                /* nested pmap: no footprint */
                *disposition_p = 0;
                return;
        }

        /*
         * Query the pmap.
         */
        pmap_query_page_info(map->pmap, curr_s_offset, &pmap_disp);

        /*
         * Compute this page's disposition.
         */
        disposition = 0;

        /* deal with "alternate accounting" first */
        if (!map_entry->is_sub_map &&
            object->vo_no_footprint) {
                /* does not count in footprint */
                assertf(!map_entry->use_pmap, "offset 0x%llx map_entry %p", (uint64_t) curr_s_offset, map_entry);
        } else if (!map_entry->is_sub_map &&
            (object->purgable == VM_PURGABLE_NONVOLATILE ||
            (object->purgable == VM_PURGABLE_DENY &&
            object->vo_ledger_tag)) &&
            VM_OBJECT_OWNER(object) != NULL &&
            VM_OBJECT_OWNER(object)->map == map) {
                assertf(!map_entry->use_pmap, "offset 0x%llx map_entry %p", (uint64_t) curr_s_offset, map_entry);
                if ((((curr_s_offset
                    - map_entry->vme_start
                    + VME_OFFSET(map_entry))
                    / effective_page_size) <
                    (object->resident_page_count +
                    vm_compressor_pager_get_count(object->pager)))) {
                        /*
                         * Non-volatile purgeable object owned
                         * by this task: report the first
                         * "#resident + #compressed" pages as
                         * "resident" (to show that they
                         * contribute to the footprint) but not
                         * "dirty" (to avoid double-counting
                         * with the fake "non-volatile" region
                         * we'll report at the end of the
                         * address space to account for all
                         * (mapped or not) non-volatile memory
                         * owned by this task.
                         */
                        disposition |= VM_PAGE_QUERY_PAGE_PRESENT;
                }
        } else if (!map_entry->is_sub_map &&
            (object->purgable == VM_PURGABLE_VOLATILE ||
            object->purgable == VM_PURGABLE_EMPTY) &&
            VM_OBJECT_OWNER(object) != NULL &&
            VM_OBJECT_OWNER(object)->map == map) {
                assertf(!map_entry->use_pmap, "offset 0x%llx map_entry %p", (uint64_t) curr_s_offset, map_entry);
                if ((((curr_s_offset
                    - map_entry->vme_start
                    + VME_OFFSET(map_entry))
                    / effective_page_size) <
                    object->wired_page_count)) {
                        /*
                         * Volatile|empty purgeable object owned
                         * by this task: report the first
                         * "#wired" pages as "resident" (to
                         * show that they contribute to the
                         * footprint) but not "dirty" (to avoid
                         * double-counting with the fake
                         * "non-volatile" region we'll report
                         * at the end of the address space to
                         * account for all (mapped or not)
                         * non-volatile memory owned by this
                         * task.
                         */
                        disposition |= VM_PAGE_QUERY_PAGE_PRESENT;
                }
        } else if (!map_entry->is_sub_map &&
            map_entry->iokit_acct &&
            object->internal &&
            object->purgable == VM_PURGABLE_DENY) {
                /*
                 * Non-purgeable IOKit memory: phys_footprint
                 * includes the entire virtual mapping.
                 */
                assertf(!map_entry->use_pmap, "offset 0x%llx map_entry %p", (uint64_t) curr_s_offset, map_entry);
                disposition |= VM_PAGE_QUERY_PAGE_PRESENT;
                disposition |= VM_PAGE_QUERY_PAGE_DIRTY;
        } else if (pmap_disp & (PMAP_QUERY_PAGE_ALTACCT |
            PMAP_QUERY_PAGE_COMPRESSED_ALTACCT)) {
                /* alternate accounting */
#if (__arm__ || __arm64__) && (DEVELOPMENT || DEBUG)
                if (map->pmap->footprint_was_suspended) {
                        /*
                         * The assertion below can fail if dyld
                         * suspended footprint accounting
                         * while doing some adjustments to
                         * this page;  the mapping would say
                         * "use pmap accounting" but the page
                         * would be marked "alternate
                         * accounting".
                         */
                } else
#endif /* (__arm__ || __arm64__) && (DEVELOPMENT || DEBUG) */
                {
                        assertf(!map_entry->use_pmap, "offset 0x%llx map_entry %p", (uint64_t) curr_s_offset, map_entry);
                }
                disposition = 0;
        } else {
                if (pmap_disp & PMAP_QUERY_PAGE_PRESENT) {
                        assertf(map_entry->use_pmap, "offset 0x%llx map_entry %p", (uint64_t) curr_s_offset, map_entry);
                        disposition |= VM_PAGE_QUERY_PAGE_PRESENT;
                        disposition |= VM_PAGE_QUERY_PAGE_REF;
                        if (pmap_disp & PMAP_QUERY_PAGE_INTERNAL) {
                                disposition |= VM_PAGE_QUERY_PAGE_DIRTY;
                        } else {
                                disposition |= VM_PAGE_QUERY_PAGE_EXTERNAL;
                        }
                        if (pmap_disp & PMAP_QUERY_PAGE_REUSABLE) {
                                disposition |= VM_PAGE_QUERY_PAGE_REUSABLE;
                        }
                } else if (pmap_disp & PMAP_QUERY_PAGE_COMPRESSED) {
                        assertf(map_entry->use_pmap, "offset 0x%llx map_entry %p", (uint64_t) curr_s_offset, map_entry);
                        disposition |= VM_PAGE_QUERY_PAGE_PAGED_OUT;
                }
        }

        *disposition_p = disposition;
}

kern_return_t
vm_map_page_query_internal(
        vm_map_t        target_map,
        vm_map_offset_t offset,
        int             *disposition,
        int             *ref_count)
{
        kern_return_t                   kr;
        vm_page_info_basic_data_t       info;
        mach_msg_type_number_t          count;

        count = VM_PAGE_INFO_BASIC_COUNT;
        kr = vm_map_page_info(target_map,
            offset,
            VM_PAGE_INFO_BASIC,
            (vm_page_info_t) &info,
            &count);
        if (kr == KERN_SUCCESS) {
                *disposition = info.disposition;
                *ref_count = info.ref_count;
        } else {
                *disposition = 0;
                *ref_count = 0;
        }

        return kr;
}

kern_return_t
vm_map_page_info(
        vm_map_t                map,
        vm_map_offset_t         offset,
        vm_page_info_flavor_t   flavor,
        vm_page_info_t          info,
        mach_msg_type_number_t  *count)
{
        return vm_map_page_range_info_internal(map,
                   offset, /* start of range */
                   (offset + 1), /* this will get rounded in the call to the page boundary */
                   (int)-1, /* effective_page_shift: unspecified */
                   flavor,
                   info,
                   count);
}

kern_return_t
vm_map_page_range_info_internal(
        vm_map_t                map,
        vm_map_offset_t         start_offset,
        vm_map_offset_t         end_offset,
        int                     effective_page_shift,
        vm_page_info_flavor_t   flavor,
        vm_page_info_t          info,
        mach_msg_type_number_t  *count)
{
        vm_map_entry_t          map_entry = VM_MAP_ENTRY_NULL;
        vm_object_t             object = VM_OBJECT_NULL, curr_object = VM_OBJECT_NULL;
        vm_page_t               m = VM_PAGE_NULL;
        kern_return_t           retval = KERN_SUCCESS;
        int                     disposition = 0;
        int                     ref_count = 0;
        int                     depth = 0, info_idx = 0;
        vm_page_info_basic_t    basic_info = 0;
        vm_map_offset_t         offset_in_page = 0, offset_in_object = 0, curr_offset_in_object = 0;
        vm_map_offset_t         start = 0, end = 0, curr_s_offset = 0, curr_e_offset = 0;
        boolean_t               do_region_footprint;
        ledger_amount_t         ledger_resident, ledger_compressed;
        int                     effective_page_size;
        vm_map_offset_t         effective_page_mask;

        switch (flavor) {
        case VM_PAGE_INFO_BASIC:
                if (*count != VM_PAGE_INFO_BASIC_COUNT) {
                        /*
                         * The "vm_page_info_basic_data" structure was not
                         * properly padded, so allow the size to be off by
                         * one to maintain backwards binary compatibility...
                         */
                        if (*count != VM_PAGE_INFO_BASIC_COUNT - 1) {
                                return KERN_INVALID_ARGUMENT;
                        }
                }
                break;
        default:
                return KERN_INVALID_ARGUMENT;
        }

        if (effective_page_shift == -1) {
                effective_page_shift = vm_self_region_page_shift_safely(map);
                if (effective_page_shift == -1) {
                        return KERN_INVALID_ARGUMENT;
                }
        }
        effective_page_size = (1 << effective_page_shift);
        effective_page_mask = effective_page_size - 1;

        do_region_footprint = task_self_region_footprint();
        disposition = 0;
        ref_count = 0;
        depth = 0;
        info_idx = 0; /* Tracks the next index within the info structure to be filled.*/
        retval = KERN_SUCCESS;

        offset_in_page = start_offset & effective_page_mask;
        start = vm_map_trunc_page(start_offset, effective_page_mask);
        end = vm_map_round_page(end_offset, effective_page_mask);

        if (end < start) {
                return KERN_INVALID_ARGUMENT;
        }

        assert((end - start) <= MAX_PAGE_RANGE_QUERY);

        vm_map_lock_read(map);

        task_ledgers_footprint(map->pmap->ledger, &ledger_resident, &ledger_compressed);

        for (curr_s_offset = start; curr_s_offset < end;) {
                /*
                 * New lookup needs reset of these variables.
                 */
                curr_object = object = VM_OBJECT_NULL;
                offset_in_object = 0;
                ref_count = 0;
                depth = 0;

                if (do_region_footprint &&
                    curr_s_offset >= vm_map_last_entry(map)->vme_end) {
                        /*
                         * Request for "footprint" info about a page beyond
                         * the end of address space: this must be for
                         * the fake region vm_map_region_recurse_64()
                         * reported to account for non-volatile purgeable
                         * memory owned by this task.
                         */
                        disposition = 0;

                        if (curr_s_offset - vm_map_last_entry(map)->vme_end <=
                            (unsigned) ledger_compressed) {
                                /*
                                 * We haven't reported all the "non-volatile
                                 * compressed" pages yet, so report this fake
                                 * page as "compressed".
                                 */
                                disposition |= VM_PAGE_QUERY_PAGE_PAGED_OUT;
                        } else {
                                /*
                                 * We've reported all the non-volatile
                                 * compressed page but not all the non-volatile
                                 * pages , so report this fake page as
                                 * "resident dirty".
                                 */
                                disposition |= VM_PAGE_QUERY_PAGE_PRESENT;
                                disposition |= VM_PAGE_QUERY_PAGE_DIRTY;
                                disposition |= VM_PAGE_QUERY_PAGE_REF;
                        }
                        switch (flavor) {
                        case VM_PAGE_INFO_BASIC:
                                basic_info = (vm_page_info_basic_t) (((uintptr_t) info) + (info_idx * sizeof(struct vm_page_info_basic)));
                                basic_info->disposition = disposition;
                                basic_info->ref_count = 1;
                                basic_info->object_id = VM_OBJECT_ID_FAKE(map, task_ledgers.purgeable_nonvolatile);
                                basic_info->offset = 0;
                                basic_info->depth = 0;

                                info_idx++;
                                break;
                        }
                        curr_s_offset += effective_page_size;
                        continue;
                }

                /*
                 * First, find the map entry covering "curr_s_offset", going down
                 * submaps if necessary.
                 */
                if (!vm_map_lookup_entry(map, curr_s_offset, &map_entry)) {
                        /* no entry -> no object -> no page */

                        if (curr_s_offset < vm_map_min(map)) {
                                /*
                                 * Illegal address that falls below map min.
                                 */
                                curr_e_offset = MIN(end, vm_map_min(map));
                        } else if (curr_s_offset >= vm_map_max(map)) {
                                /*
                                 * Illegal address that falls on/after map max.
                                 */
                                curr_e_offset = end;
                        } else if (map_entry == vm_map_to_entry(map)) {
                                /*
                                 * Hit a hole.
                                 */
                                if (map_entry->vme_next == vm_map_to_entry(map)) {
                                        /*
                                         * Empty map.
                                         */
                                        curr_e_offset = MIN(map->max_offset, end);
                                } else {
                                        /*
                                         * Hole at start of the map.
                                         */
                                        curr_e_offset = MIN(map_entry->vme_next->vme_start, end);
                                }
                        } else {
                                if (map_entry->vme_next == vm_map_to_entry(map)) {
                                        /*
                                         * Hole at the end of the map.
                                         */
                                        curr_e_offset = MIN(map->max_offset, end);
                                } else {
                                        curr_e_offset = MIN(map_entry->vme_next->vme_start, end);
                                }
                        }

                        assert(curr_e_offset >= curr_s_offset);

                        uint64_t num_pages = (curr_e_offset - curr_s_offset) >> effective_page_shift;

                        void *info_ptr = (void*) (((uintptr_t) info) + (info_idx * sizeof(struct vm_page_info_basic)));

                        bzero(info_ptr, num_pages * sizeof(struct vm_page_info_basic));

                        curr_s_offset = curr_e_offset;

                        info_idx += num_pages;

                        continue;
                }

                /* compute offset from this map entry's start */
                offset_in_object = curr_s_offset - map_entry->vme_start;

                /* compute offset into this map entry's object (or submap) */
                offset_in_object += VME_OFFSET(map_entry);

                if (map_entry->is_sub_map) {
                        vm_map_t sub_map = VM_MAP_NULL;
                        vm_page_info_t submap_info = 0;
                        vm_map_offset_t submap_s_offset = 0, submap_e_offset = 0, range_len = 0;

                        range_len = MIN(map_entry->vme_end, end) - curr_s_offset;

                        submap_s_offset = offset_in_object;
                        submap_e_offset = submap_s_offset + range_len;

                        sub_map = VME_SUBMAP(map_entry);

                        vm_map_reference(sub_map);
                        vm_map_unlock_read(map);

                        submap_info = (vm_page_info_t) (((uintptr_t) info) + (info_idx * sizeof(struct vm_page_info_basic)));

                        assertf(VM_MAP_PAGE_SHIFT(sub_map) >= VM_MAP_PAGE_SHIFT(map),
                            "Submap page size (%d) differs from current map (%d)\n", VM_MAP_PAGE_SIZE(sub_map), VM_MAP_PAGE_SIZE(map));

                        retval = vm_map_page_range_info_internal(sub_map,
                            submap_s_offset,
                            submap_e_offset,
                            effective_page_shift,
                            VM_PAGE_INFO_BASIC,
                            (vm_page_info_t) submap_info,
                            count);

                        assert(retval == KERN_SUCCESS);

                        vm_map_lock_read(map);
                        vm_map_deallocate(sub_map);

                        /* Move the "info" index by the number of pages we inspected.*/
                        info_idx += range_len >> effective_page_shift;

                        /* Move our current offset by the size of the range we inspected.*/
                        curr_s_offset += range_len;

                        continue;
                }

                object = VME_OBJECT(map_entry);

                if (object == VM_OBJECT_NULL) {
                        /*
                         * We don't have an object here and, hence,
                         * no pages to inspect. We'll fill up the
                         * info structure appropriately.
                         */

                        curr_e_offset = MIN(map_entry->vme_end, end);

                        uint64_t num_pages = (curr_e_offset - curr_s_offset) >> effective_page_shift;

                        void *info_ptr = (void*) (((uintptr_t) info) + (info_idx * sizeof(struct vm_page_info_basic)));

                        bzero(info_ptr, num_pages * sizeof(struct vm_page_info_basic));

                        curr_s_offset = curr_e_offset;

                        info_idx += num_pages;

                        continue;
                }

                if (do_region_footprint) {
                        disposition = 0;
                        if (map->has_corpse_footprint) {
                                /*
                                 * Query the page info data we saved
                                 * while forking the corpse.
                                 */
                                vm_map_corpse_footprint_query_page_info(
                                        map,
                                        curr_s_offset,
                                        &disposition);
                        } else {
                                /*
                                 * Query the live pmap for footprint info
                                 * about this page.
                                 */
                                vm_map_footprint_query_page_info(
                                        map,
                                        map_entry,
                                        curr_s_offset,
                                        &disposition);
                        }
                        switch (flavor) {
                        case VM_PAGE_INFO_BASIC:
                                basic_info = (vm_page_info_basic_t) (((uintptr_t) info) + (info_idx * sizeof(struct vm_page_info_basic)));
                                basic_info->disposition = disposition;
                                basic_info->ref_count = 1;
                                basic_info->object_id = VM_OBJECT_ID_FAKE(map, task_ledgers.purgeable_nonvolatile);
                                basic_info->offset = 0;
                                basic_info->depth = 0;

                                info_idx++;
                                break;
                        }
                        curr_s_offset += effective_page_size;
                        continue;
                }

                vm_object_reference(object);
                /*
                 * Shared mode -- so we can allow other readers
                 * to grab the lock too.
                 */
                vm_object_lock_shared(object);

                curr_e_offset = MIN(map_entry->vme_end, end);

                vm_map_unlock_read(map);

                map_entry = NULL; /* map is unlocked, the entry is no longer valid. */

                curr_object = object;

                for (; curr_s_offset < curr_e_offset;) {
                        if (object == curr_object) {
                                ref_count = curr_object->ref_count - 1; /* account for our object reference above. */
                        } else {
                                ref_count = curr_object->ref_count;
                        }

                        curr_offset_in_object = offset_in_object;

                        for (;;) {
                                m = vm_page_lookup(curr_object, vm_object_trunc_page(curr_offset_in_object));

                                if (m != VM_PAGE_NULL) {
                                        disposition |= VM_PAGE_QUERY_PAGE_PRESENT;
                                        break;
                                } else {
                                        if (curr_object->internal &&
                                            curr_object->alive &&
                                            !curr_object->terminating &&
                                            curr_object->pager_ready) {
                                                if (VM_COMPRESSOR_PAGER_STATE_GET(curr_object, vm_object_trunc_page(curr_offset_in_object))
                                                    == VM_EXTERNAL_STATE_EXISTS) {
                                                        /* the pager has that page */
                                                        disposition |= VM_PAGE_QUERY_PAGE_PAGED_OUT;
                                                        break;
                                                }
                                        }

                                        /*
                                         * Go down the VM object shadow chain until we find the page
                                         * we're looking for.
                                         */

                                        if (curr_object->shadow != VM_OBJECT_NULL) {
                                                vm_object_t shadow = VM_OBJECT_NULL;

                                                curr_offset_in_object += curr_object->vo_shadow_offset;
                                                shadow = curr_object->shadow;

                                                vm_object_lock_shared(shadow);
                                                vm_object_unlock(curr_object);

                                                curr_object = shadow;
                                                depth++;
                                                continue;
                                        } else {
                                                break;
                                        }
                                }
                        }

                        /* The ref_count is not strictly accurate, it measures the number   */
                        /* of entities holding a ref on the object, they may not be mapping */
                        /* the object or may not be mapping the section holding the         */
                        /* target page but its still a ball park number and though an over- */
                        /* count, it picks up the copy-on-write cases                       */

                        /* We could also get a picture of page sharing from pmap_attributes */
                        /* but this would under count as only faulted-in mappings would     */
                        /* show up.                                                         */

                        if ((curr_object == object) && curr_object->shadow) {
                                disposition |= VM_PAGE_QUERY_PAGE_COPIED;
                        }

                        if (!curr_object->internal) {
                                disposition |= VM_PAGE_QUERY_PAGE_EXTERNAL;
                        }

                        if (m != VM_PAGE_NULL) {
                                if (m->vmp_fictitious) {
                                        disposition |= VM_PAGE_QUERY_PAGE_FICTITIOUS;
                                } else {
                                        if (m->vmp_dirty || pmap_is_modified(VM_PAGE_GET_PHYS_PAGE(m))) {
                                                disposition |= VM_PAGE_QUERY_PAGE_DIRTY;
                                        }

                                        if (m->vmp_reference || pmap_is_referenced(VM_PAGE_GET_PHYS_PAGE(m))) {
                                                disposition |= VM_PAGE_QUERY_PAGE_REF;
                                        }

                                        if (m->vmp_q_state == VM_PAGE_ON_SPECULATIVE_Q) {
                                                disposition |= VM_PAGE_QUERY_PAGE_SPECULATIVE;
                                        }

                                        /*
                                         * XXX TODO4K:
                                         * when this routine deals with 4k
                                         * pages, check the appropriate CS bit
                                         * here.
                                         */
                                        if (m->vmp_cs_validated) {
                                                disposition |= VM_PAGE_QUERY_PAGE_CS_VALIDATED;
                                        }
                                        if (m->vmp_cs_tainted) {
                                                disposition |= VM_PAGE_QUERY_PAGE_CS_TAINTED;
                                        }
                                        if (m->vmp_cs_nx) {
                                                disposition |= VM_PAGE_QUERY_PAGE_CS_NX;
                                        }
                                        if (m->vmp_reusable || curr_object->all_reusable) {
                                                disposition |= VM_PAGE_QUERY_PAGE_REUSABLE;
                                        }
                                }
                        }

                        switch (flavor) {
                        case VM_PAGE_INFO_BASIC:
                                basic_info = (vm_page_info_basic_t) (((uintptr_t) info) + (info_idx * sizeof(struct vm_page_info_basic)));
                                basic_info->disposition = disposition;
                                basic_info->ref_count = ref_count;
                                basic_info->object_id = (vm_object_id_t) (uintptr_t)
                                    VM_KERNEL_ADDRPERM(curr_object);
                                basic_info->offset =
                                    (memory_object_offset_t) curr_offset_in_object + offset_in_page;
                                basic_info->depth = depth;

                                info_idx++;
                                break;
                        }

                        disposition = 0;
                        offset_in_page = 0; // This doesn't really make sense for any offset other than the starting offset.

                        /*
                         * Move to next offset in the range and in our object.
                         */
                        curr_s_offset += effective_page_size;
                        offset_in_object += effective_page_size;
                        curr_offset_in_object = offset_in_object;

                        if (curr_object != object) {
                                vm_object_unlock(curr_object);

                                curr_object = object;

                                vm_object_lock_shared(curr_object);
                        } else {
                                vm_object_lock_yield_shared(curr_object);
                        }
                }

                vm_object_unlock(curr_object);
                vm_object_deallocate(curr_object);

                vm_map_lock_read(map);
        }

        vm_map_unlock_read(map);
        return retval;
}

/*
 *      vm_map_msync
 *
 *      Synchronises the memory range specified with its backing store
 *      image by either flushing or cleaning the contents to the appropriate
 *      memory manager engaging in a memory object synchronize dialog with
 *      the manager.  The client doesn't return until the manager issues
 *      m_o_s_completed message.  MIG Magically converts user task parameter
 *      to the task's address map.
 *
 *      interpretation of sync_flags
 *      VM_SYNC_INVALIDATE      - discard pages, only return precious
 *                                pages to manager.
 *
 *      VM_SYNC_INVALIDATE & (VM_SYNC_SYNCHRONOUS | VM_SYNC_ASYNCHRONOUS)
 *                              - discard pages, write dirty or precious
 *                                pages back to memory manager.
 *
 *      VM_SYNC_SYNCHRONOUS | VM_SYNC_ASYNCHRONOUS
 *                              - write dirty or precious pages back to
 *                                the memory manager.
 *
 *      VM_SYNC_CONTIGUOUS      - does everything normally, but if there
 *                                is a hole in the region, and we would
 *                                have returned KERN_SUCCESS, return
 *                                KERN_INVALID_ADDRESS instead.
 *
 *      NOTE
 *      The memory object attributes have not yet been implemented, this
 *      function will have to deal with the invalidate attribute
 *
 *      RETURNS
 *      KERN_INVALID_TASK               Bad task parameter
 *      KERN_INVALID_ARGUMENT           both sync and async were specified.
 *      KERN_SUCCESS                    The usual.
 *      KERN_INVALID_ADDRESS            There was a hole in the region.
 */

kern_return_t
vm_map_msync(
        vm_map_t                map,
        vm_map_address_t        address,
        vm_map_size_t           size,
        vm_sync_t               sync_flags)
{
        vm_map_entry_t          entry;
        vm_map_size_t           amount_left;
        vm_object_offset_t      offset;
        vm_object_offset_t      start_offset, end_offset;
        boolean_t               do_sync_req;
        boolean_t               had_hole = FALSE;
        vm_map_offset_t         pmap_offset;

        if ((sync_flags & VM_SYNC_ASYNCHRONOUS) &&
            (sync_flags & VM_SYNC_SYNCHRONOUS)) {
                return KERN_INVALID_ARGUMENT;
        }

        if (VM_MAP_PAGE_MASK(map) < PAGE_MASK) {
                DEBUG4K_SHARE("map %p address 0x%llx size 0x%llx flags 0x%x\n", map, (uint64_t)address, (uint64_t)size, sync_flags);
        }

        /*
         * align address and size on page boundaries
         */
        size = (vm_map_round_page(address + size,
            VM_MAP_PAGE_MASK(map)) -
            vm_map_trunc_page(address,
            VM_MAP_PAGE_MASK(map)));
        address = vm_map_trunc_page(address,
            VM_MAP_PAGE_MASK(map));

        if (map == VM_MAP_NULL) {
                return KERN_INVALID_TASK;
        }

        if (size == 0) {
                return KERN_SUCCESS;
        }

        amount_left = size;

        while (amount_left > 0) {
                vm_object_size_t        flush_size;
                vm_object_t             object;

                vm_map_lock(map);
                if (!vm_map_lookup_entry(map,
                    address,
                    &entry)) {
                        vm_map_size_t   skip;

                        /*
                         * hole in the address map.
                         */
                        had_hole = TRUE;

                        if (sync_flags & VM_SYNC_KILLPAGES) {
                                /*
                                 * For VM_SYNC_KILLPAGES, there should be
                                 * no holes in the range, since we couldn't
                                 * prevent someone else from allocating in
                                 * that hole and we wouldn't want to "kill"
                                 * their pages.
                                 */
                                vm_map_unlock(map);
                                break;
                        }

                        /*
                         * Check for empty map.
                         */
                        if (entry == vm_map_to_entry(map) &&
                            entry->vme_next == entry) {
                                vm_map_unlock(map);
                                break;
                        }
                        /*
                         * Check that we don't wrap and that
                         * we have at least one real map entry.
                         */
                        if ((map->hdr.nentries == 0) ||
                            (entry->vme_next->vme_start < address)) {
                                vm_map_unlock(map);
                                break;
                        }
                        /*
                         * Move up to the next entry if needed
                         */
                        skip = (entry->vme_next->vme_start - address);
                        if (skip >= amount_left) {
                                amount_left = 0;
                        } else {
                                amount_left -= skip;
                        }
                        address = entry->vme_next->vme_start;
                        vm_map_unlock(map);
                        continue;
                }

                offset = address - entry->vme_start;
                pmap_offset = address;

                /*
                 * do we have more to flush than is contained in this
                 * entry ?
                 */
                if (amount_left + entry->vme_start + offset > entry->vme_end) {
                        flush_size = entry->vme_end -
                            (entry->vme_start + offset);
                } else {
                        flush_size = amount_left;
                }
                amount_left -= flush_size;
                address += flush_size;

                if (entry->is_sub_map == TRUE) {
                        vm_map_t        local_map;
                        vm_map_offset_t local_offset;

                        local_map = VME_SUBMAP(entry);
                        local_offset = VME_OFFSET(entry);
                        vm_map_reference(local_map);
                        vm_map_unlock(map);
                        if (vm_map_msync(
                                    local_map,
                                    local_offset,
                                    flush_size,
                                    sync_flags) == KERN_INVALID_ADDRESS) {
                                had_hole = TRUE;
                        }
                        vm_map_deallocate(local_map);
                        continue;
                }
                object = VME_OBJECT(entry);

                /*
                 * We can't sync this object if the object has not been
                 * created yet
                 */
                if (object == VM_OBJECT_NULL) {
                        vm_map_unlock(map);
                        continue;
                }
                offset += VME_OFFSET(entry);

                vm_object_lock(object);

                if (sync_flags & (VM_SYNC_KILLPAGES | VM_SYNC_DEACTIVATE)) {
                        int kill_pages = 0;
                        boolean_t reusable_pages = FALSE;

                        if (VM_MAP_PAGE_MASK(map) < PAGE_MASK) {
                                /*
                                 * This is a destructive operation and so we
                                 * err on the side of limiting the range of
                                 * the operation.
                                 */
                                start_offset = vm_object_round_page(offset);
                                end_offset = vm_object_trunc_page(offset + flush_size);

                                if (end_offset <= start_offset) {
                                        vm_object_unlock(object);
                                        vm_map_unlock(map);
                                        continue;
                                }

                                pmap_offset += start_offset - offset;;
                        } else {
                                start_offset = offset;
                                end_offset = offset + flush_size;
                        }

                        if (sync_flags & VM_SYNC_KILLPAGES) {
                                if (((object->ref_count == 1) ||
                                    ((object->copy_strategy !=
                                    MEMORY_OBJECT_COPY_SYMMETRIC) &&
                                    (object->copy == VM_OBJECT_NULL))) &&
                                    (object->shadow == VM_OBJECT_NULL)) {
                                        if (object->ref_count != 1) {
                                                vm_page_stats_reusable.free_shared++;
                                        }
                                        kill_pages = 1;
                                } else {
                                        kill_pages = -1;
                                }
                        }
                        if (kill_pages != -1) {
                                vm_object_deactivate_pages(
                                        object,
                                        start_offset,
                                        (vm_object_size_t) (end_offset - start_offset),
                                        kill_pages,
                                        reusable_pages,
                                        map->pmap,
                                        pmap_offset);
                        }
                        vm_object_unlock(object);
                        vm_map_unlock(map);
                        continue;
                }
                /*
                 * We can't sync this object if there isn't a pager.
                 * Don't bother to sync internal objects, since there can't
                 * be any "permanent" storage for these objects anyway.
                 */
                if ((object->pager == MEMORY_OBJECT_NULL) ||
                    (object->internal) || (object->private)) {
                        vm_object_unlock(object);
                        vm_map_unlock(map);
                        continue;
                }
                /*
                 * keep reference on the object until syncing is done
                 */
                vm_object_reference_locked(object);
                vm_object_unlock(object);

                vm_map_unlock(map);

                if (VM_MAP_PAGE_MASK(map) < PAGE_MASK) {
                        start_offset = vm_object_trunc_page(offset);
                        end_offset = vm_object_round_page(offset + flush_size);
                } else {
                        start_offset = offset;
                        end_offset = offset + flush_size;
                }

                do_sync_req = vm_object_sync(object,
                    start_offset,
                    (end_offset - start_offset),
                    sync_flags & VM_SYNC_INVALIDATE,
                    ((sync_flags & VM_SYNC_SYNCHRONOUS) ||
                    (sync_flags & VM_SYNC_ASYNCHRONOUS)),
                    sync_flags & VM_SYNC_SYNCHRONOUS);

                if ((sync_flags & VM_SYNC_INVALIDATE) && object->resident_page_count == 0) {
                        /*
                         * clear out the clustering and read-ahead hints
                         */
                        vm_object_lock(object);

                        object->pages_created = 0;
                        object->pages_used = 0;
                        object->sequential = 0;
                        object->last_alloc = 0;

                        vm_object_unlock(object);
                }
                vm_object_deallocate(object);
        } /* while */

        /* for proper msync() behaviour */
        if (had_hole == TRUE && (sync_flags & VM_SYNC_CONTIGUOUS)) {
                return KERN_INVALID_ADDRESS;
        }

        return KERN_SUCCESS;
}/* vm_msync */

kern_return_t
vm_named_entry_from_vm_object(
        vm_named_entry_t        named_entry,
        vm_object_t             object,
        vm_object_offset_t      offset,
        vm_object_size_t        size,
        vm_prot_t               prot)
{
        vm_map_copy_t copy;
        vm_map_entry_t copy_entry;

        assert(!named_entry->is_sub_map);
        assert(!named_entry->is_copy);
        assert(!named_entry->is_object);
        assert(!named_entry->internal);
        assert(named_entry->backing.copy == VM_MAP_COPY_NULL);

        copy = vm_map_copy_allocate();
        copy->type = VM_MAP_COPY_ENTRY_LIST;
        copy->offset = offset;
        copy->size = size;
        copy->cpy_hdr.page_shift = PAGE_SHIFT;
        vm_map_store_init(&copy->cpy_hdr);

        copy_entry = vm_map_copy_entry_create(copy, FALSE);
        copy_entry->protection = prot;
        copy_entry->max_protection = prot;
        copy_entry->use_pmap = TRUE;
        copy_entry->vme_start = VM_MAP_TRUNC_PAGE(offset, PAGE_MASK);
        copy_entry->vme_end = VM_MAP_ROUND_PAGE(offset + size, PAGE_MASK);
        VME_OBJECT_SET(copy_entry, object);
        VME_OFFSET_SET(copy_entry, vm_object_trunc_page(offset));
        vm_map_copy_entry_link(copy, vm_map_copy_last_entry(copy), copy_entry);

        named_entry->backing.copy = copy;
        named_entry->is_object = TRUE;
        if (object->internal) {
                named_entry->internal = TRUE;
        }

        DEBUG4K_MEMENTRY("named_entry %p copy %p object %p offset 0x%llx size 0x%llx prot 0x%x\n", named_entry, copy, object, offset, size, prot);

        return KERN_SUCCESS;
}

vm_object_t
vm_named_entry_to_vm_object(
        vm_named_entry_t named_entry)
{
        vm_map_copy_t   copy;
        vm_map_entry_t  copy_entry;
        vm_object_t     object;

        assert(!named_entry->is_sub_map);
        assert(!named_entry->is_copy);
        assert(named_entry->is_object);
        copy = named_entry->backing.copy;
        assert(copy != VM_MAP_COPY_NULL);
        assert(copy->cpy_hdr.nentries == 1);
        copy_entry = vm_map_copy_first_entry(copy);
        assert(!copy_entry->is_sub_map);
        object = VME_OBJECT(copy_entry);

        DEBUG4K_MEMENTRY("%p -> %p -> %p [0x%llx 0x%llx 0x%llx 0x%x/0x%x ] -> %p offset 0x%llx size 0x%llx prot 0x%x\n", named_entry, copy, copy_entry, (uint64_t)copy_entry->vme_start, (uint64_t)copy_entry->vme_end, copy_entry->vme_offset, copy_entry->protection, copy_entry->max_protection, object, named_entry->offset, named_entry->size, named_entry->protection);

        return object;
}

/*
 *      Routine:        convert_port_entry_to_map
 *      Purpose:
 *              Convert from a port specifying an entry or a task
 *              to a map. Doesn't consume the port ref; produces a map ref,
 *              which may be null.  Unlike convert_port_to_map, the
 *              port may be task or a named entry backed.
 *      Conditions:
 *              Nothing locked.
 */


vm_map_t
convert_port_entry_to_map(
        ipc_port_t      port)
{
        vm_map_t map;
        vm_named_entry_t        named_entry;
        uint32_t        try_failed_count = 0;

        if (IP_VALID(port) && (ip_kotype(port) == IKOT_NAMED_ENTRY)) {
                while (TRUE) {
                        ip_lock(port);
                        if (ip_active(port) && (ip_kotype(port)
                            == IKOT_NAMED_ENTRY)) {
                                named_entry =
                                    (vm_named_entry_t) ip_get_kobject(port);
                                if (!(lck_mtx_try_lock(&(named_entry)->Lock))) {
                                        ip_unlock(port);

                                        try_failed_count++;
                                        mutex_pause(try_failed_count);
                                        continue;
                                }
                                named_entry->ref_count++;
                                lck_mtx_unlock(&(named_entry)->Lock);
                                ip_unlock(port);
                                if ((named_entry->is_sub_map) &&
                                    (named_entry->protection
                                    & VM_PROT_WRITE)) {
                                        map = named_entry->backing.map;
                                        if (map->pmap != PMAP_NULL) {
                                                if (map->pmap == kernel_pmap) {
                                                        panic("userspace has access "
                                                            "to a kernel map %p", map);
                                                }
                                                pmap_require(map->pmap);
                                        }
                                } else {
                                        mach_destroy_memory_entry(port);
                                        return VM_MAP_NULL;
                                }
                                vm_map_reference_swap(map);
                                mach_destroy_memory_entry(port);
                                break;
                        } else {
                                return VM_MAP_NULL;
                        }
                }
        } else {
                map = convert_port_to_map(port);
        }

        return map;
}

/*
 *      Routine:        convert_port_entry_to_object
 *      Purpose:
 *              Convert from a port specifying a named entry to an
 *              object. Doesn't consume the port ref; produces a map ref,
 *              which may be null.
 *      Conditions:
 *              Nothing locked.
 */


vm_object_t
convert_port_entry_to_object(
        ipc_port_t      port)
{
        vm_object_t             object = VM_OBJECT_NULL;
        vm_named_entry_t        named_entry;
        uint32_t                try_failed_count = 0;

        if (IP_VALID(port) &&
            (ip_kotype(port) == IKOT_NAMED_ENTRY)) {
try_again:
                ip_lock(port);
                if (ip_active(port) &&
                    (ip_kotype(port) == IKOT_NAMED_ENTRY)) {
                        named_entry = (vm_named_entry_t) ip_get_kobject(port);
                        if (!(lck_mtx_try_lock(&(named_entry)->Lock))) {
                                ip_unlock(port);
                                try_failed_count++;
                                mutex_pause(try_failed_count);
                                goto try_again;
                        }
                        named_entry->ref_count++;
                        lck_mtx_unlock(&(named_entry)->Lock);
                        ip_unlock(port);
                        if (!(named_entry->is_sub_map) &&
                            !(named_entry->is_copy) &&
                            (named_entry->is_object) &&
                            (named_entry->protection & VM_PROT_WRITE)) {
                                vm_map_copy_t copy;
                                vm_map_entry_t copy_entry;

                                copy = named_entry->backing.copy;
                                assert(copy->cpy_hdr.nentries == 1);
                                copy_entry = vm_map_copy_first_entry(copy);
                                assert(!copy_entry->is_sub_map);
                                object = VME_OBJECT(copy_entry);
                                assert(object != VM_OBJECT_NULL);
                                vm_object_reference(object);
                        }
                        mach_destroy_memory_entry(port);
                }
        }

        return object;
}

/*
 * Export routines to other components for the things we access locally through
 * macros.
 */
#undef current_map
vm_map_t
current_map(void)
{
        return current_map_fast();
}

/*
 *      vm_map_reference:
 *
 *      Most code internal to the osfmk will go through a
 *      macro defining this.  This is always here for the
 *      use of other kernel components.
 */
#undef vm_map_reference
void
vm_map_reference(
        vm_map_t        map)
{
        if (map == VM_MAP_NULL) {
                return;
        }

        lck_mtx_lock(&map->s_lock);
#if     TASK_SWAPPER
        assert(map->res_count > 0);
        assert(os_ref_get_count(&map->map_refcnt) >= map->res_count);
        map->res_count++;
#endif
        os_ref_retain_locked(&map->map_refcnt);
        lck_mtx_unlock(&map->s_lock);
}

/*
 *      vm_map_deallocate:
 *
 *      Removes a reference from the specified map,
 *      destroying it if no references remain.
 *      The map should not be locked.
 */
void
vm_map_deallocate(
        vm_map_t        map)
{
        unsigned int            ref;

        if (map == VM_MAP_NULL) {
                return;
        }

        lck_mtx_lock(&map->s_lock);
        ref = os_ref_release_locked(&map->map_refcnt);
        if (ref > 0) {
                vm_map_res_deallocate(map);
                lck_mtx_unlock(&map->s_lock);
                return;
        }
        assert(os_ref_get_count(&map->map_refcnt) == 0);
        lck_mtx_unlock(&map->s_lock);

#if     TASK_SWAPPER
        /*
         * The map residence count isn't decremented here because
         * the vm_map_delete below will traverse the entire map,
         * deleting entries, and the residence counts on objects
         * and sharing maps will go away then.
         */
#endif

        vm_map_destroy(map, VM_MAP_REMOVE_NO_FLAGS);
}

void
vm_map_inspect_deallocate(
        vm_map_inspect_t      map)
{
        vm_map_deallocate((vm_map_t)map);
}

void
vm_map_read_deallocate(
        vm_map_read_t      map)
{
        vm_map_deallocate((vm_map_t)map);
}


void
vm_map_disable_NX(vm_map_t map)
{
        if (map == NULL) {
                return;
        }
        if (map->pmap == NULL) {
                return;
        }

        pmap_disable_NX(map->pmap);
}

void
vm_map_disallow_data_exec(vm_map_t map)
{
        if (map == NULL) {
                return;
        }

        map->map_disallow_data_exec = TRUE;
}

/* XXX Consider making these constants (VM_MAX_ADDRESS and MACH_VM_MAX_ADDRESS)
 * more descriptive.
 */
void
vm_map_set_32bit(vm_map_t map)
{
#if defined(__arm__) || defined(__arm64__)
        map->max_offset = pmap_max_offset(FALSE, ARM_PMAP_MAX_OFFSET_DEVICE);
#else
        map->max_offset = (vm_map_offset_t)VM_MAX_ADDRESS;
#endif
}


void
vm_map_set_64bit(vm_map_t map)
{
#if defined(__arm__) || defined(__arm64__)
        map->max_offset = pmap_max_offset(TRUE, ARM_PMAP_MAX_OFFSET_DEVICE);
#else
        map->max_offset = (vm_map_offset_t)MACH_VM_MAX_ADDRESS;
#endif
}

/*
 * Expand the maximum size of an existing map to the maximum supported.
 */
void
vm_map_set_jumbo(vm_map_t map)
{
#if defined (__arm64__) && !defined(CONFIG_ARROW)
        vm_map_set_max_addr(map, ~0);
#else /* arm64 */
        (void) map;
#endif
}

/*
 * This map has a JIT entitlement
 */
void
vm_map_set_jit_entitled(vm_map_t map)
{
#if defined (__arm64__)
        pmap_set_jit_entitled(map->pmap);
#else /* arm64 */
        (void) map;
#endif
}

/*
 * Expand the maximum size of an existing map.
 */
void
vm_map_set_max_addr(vm_map_t map, vm_map_offset_t new_max_offset)
{
#if defined(__arm64__)
        vm_map_offset_t max_supported_offset = 0;
        vm_map_offset_t old_max_offset = map->max_offset;
        max_supported_offset = pmap_max_offset(vm_map_is_64bit(map), ARM_PMAP_MAX_OFFSET_JUMBO);

        new_max_offset = trunc_page(new_max_offset);

        /* The address space cannot be shrunk using this routine. */
        if (old_max_offset >= new_max_offset) {
                return;
        }

        if (max_supported_offset < new_max_offset) {
                new_max_offset = max_supported_offset;
        }

        map->max_offset = new_max_offset;

        if (map->holes_list->prev->vme_end == old_max_offset) {
                /*
                 * There is already a hole at the end of the map; simply make it bigger.
                 */
                map->holes_list->prev->vme_end = map->max_offset;
        } else {
                /*
                 * There is no hole at the end, so we need to create a new hole
                 * for the new empty space we're creating.
                 */
                struct vm_map_links *new_hole = zalloc(vm_map_holes_zone);
                new_hole->start = old_max_offset;
                new_hole->end = map->max_offset;
                new_hole->prev = map->holes_list->prev;
                new_hole->next = (struct vm_map_entry *)map->holes_list;
                map->holes_list->prev->links.next = (struct vm_map_entry *)new_hole;
                map->holes_list->prev = (struct vm_map_entry *)new_hole;
        }
#else
        (void)map;
        (void)new_max_offset;
#endif
}

vm_map_offset_t
vm_compute_max_offset(boolean_t is64)
{
#if defined(__arm__) || defined(__arm64__)
        return pmap_max_offset(is64, ARM_PMAP_MAX_OFFSET_DEVICE);
#else
        return is64 ? (vm_map_offset_t)MACH_VM_MAX_ADDRESS : (vm_map_offset_t)VM_MAX_ADDRESS;
#endif
}

void
vm_map_get_max_aslr_slide_section(
        vm_map_t                map __unused,
        int64_t                 *max_sections,
        int64_t                 *section_size)
{
#if defined(__arm64__)
        *max_sections = 3;
        *section_size = ARM_TT_TWIG_SIZE;
#else
        *max_sections = 1;
        *section_size = 0;
#endif
}

uint64_t
vm_map_get_max_aslr_slide_pages(vm_map_t map)
{
#if defined(__arm64__)
        /* Limit arm64 slide to 16MB to conserve contiguous VA space in the more
         * limited embedded address space; this is also meant to minimize pmap
         * memory usage on 16KB page systems.
         */
        return 1 << (24 - VM_MAP_PAGE_SHIFT(map));
#else
        return 1 << (vm_map_is_64bit(map) ? 16 : 8);
#endif
}

uint64_t
vm_map_get_max_loader_aslr_slide_pages(vm_map_t map)
{
#if defined(__arm64__)
        /* We limit the loader slide to 4MB, in order to ensure at least 8 bits
         * of independent entropy on 16KB page systems.
         */
        return 1 << (22 - VM_MAP_PAGE_SHIFT(map));
#else
        return 1 << (vm_map_is_64bit(map) ? 16 : 8);
#endif
}

#ifndef __arm__
boolean_t
vm_map_is_64bit(
        vm_map_t map)
{
        return map->max_offset > ((vm_map_offset_t)VM_MAX_ADDRESS);
}
#endif

boolean_t
vm_map_has_hard_pagezero(
        vm_map_t        map,
        vm_map_offset_t pagezero_size)
{
        /*
         * XXX FBDP
         * We should lock the VM map (for read) here but we can get away
         * with it for now because there can't really be any race condition:
         * the VM map's min_offset is changed only when the VM map is created
         * and when the zero page is established (when the binary gets loaded),
         * and this routine gets called only when the task terminates and the
         * VM map is being torn down, and when a new map is created via
         * load_machfile()/execve().
         */
        return map->min_offset >= pagezero_size;
}

/*
 * Raise a VM map's maximun offset.
 */
kern_return_t
vm_map_raise_max_offset(
        vm_map_t        map,
        vm_map_offset_t new_max_offset)
{
        kern_return_t   ret;

        vm_map_lock(map);
        ret = KERN_INVALID_ADDRESS;

        if (new_max_offset >= map->max_offset) {
                if (!vm_map_is_64bit(map)) {
                        if (new_max_offset <= (vm_map_offset_t)VM_MAX_ADDRESS) {
                                map->max_offset = new_max_offset;
                                ret = KERN_SUCCESS;
                        }
                } else {
                        if (new_max_offset <= (vm_map_offset_t)MACH_VM_MAX_ADDRESS) {
                                map->max_offset = new_max_offset;
                                ret = KERN_SUCCESS;
                        }
                }
        }

        vm_map_unlock(map);
        return ret;
}


/*
 * Raise a VM map's minimum offset.
 * To strictly enforce "page zero" reservation.
 */
kern_return_t
vm_map_raise_min_offset(
        vm_map_t        map,
        vm_map_offset_t new_min_offset)
{
        vm_map_entry_t  first_entry;

        new_min_offset = vm_map_round_page(new_min_offset,
            VM_MAP_PAGE_MASK(map));

        vm_map_lock(map);

        if (new_min_offset < map->min_offset) {
                /*
                 * Can't move min_offset backwards, as that would expose
                 * a part of the address space that was previously, and for
                 * possibly good reasons, inaccessible.
                 */
                vm_map_unlock(map);
                return KERN_INVALID_ADDRESS;
        }
        if (new_min_offset >= map->max_offset) {
                /* can't go beyond the end of the address space */
                vm_map_unlock(map);
                return KERN_INVALID_ADDRESS;
        }

        first_entry = vm_map_first_entry(map);
        if (first_entry != vm_map_to_entry(map) &&
            first_entry->vme_start < new_min_offset) {
                /*
                 * Some memory was already allocated below the new
                 * minimun offset.  It's too late to change it now...
                 */
                vm_map_unlock(map);
                return KERN_NO_SPACE;
        }

        map->min_offset = new_min_offset;

        assert(map->holes_list);
        map->holes_list->start = new_min_offset;
        assert(new_min_offset < map->holes_list->end);

        vm_map_unlock(map);

        return KERN_SUCCESS;
}

/*
 * Set the limit on the maximum amount of user wired memory allowed for this map.
 * This is basically a copy of the MEMLOCK rlimit value maintained by the BSD side of
 * the kernel.  The limits are checked in the mach VM side, so we keep a copy so we
 * don't have to reach over to the BSD data structures.
 */

void
vm_map_set_user_wire_limit(vm_map_t     map,
    vm_size_t    limit)
{
        map->user_wire_limit = limit;
}


void
vm_map_switch_protect(vm_map_t     map,
    boolean_t    val)
{
        vm_map_lock(map);
        map->switch_protect = val;
        vm_map_unlock(map);
}

extern int cs_process_enforcement_enable;
boolean_t
vm_map_cs_enforcement(
        vm_map_t map)
{
        if (cs_process_enforcement_enable) {
                return TRUE;
        }
        return map->cs_enforcement;
}

void
vm_map_cs_enforcement_set(
        vm_map_t map,
        boolean_t val)
{
        vm_map_lock(map);
        map->cs_enforcement = val;
        pmap_set_vm_map_cs_enforced(map->pmap, val);
        vm_map_unlock(map);
}

/*
 * IOKit has mapped a region into this map; adjust the pmap's ledgers appropriately.
 * phys_footprint is a composite limit consisting of iokit + physmem, so we need to
 * bump both counters.
 */
void
vm_map_iokit_mapped_region(vm_map_t map, vm_size_t bytes)
{
        pmap_t pmap = vm_map_pmap(map);

        ledger_credit(pmap->ledger, task_ledgers.iokit_mapped, bytes);
        ledger_credit(pmap->ledger, task_ledgers.phys_footprint, bytes);
}

void
vm_map_iokit_unmapped_region(vm_map_t map, vm_size_t bytes)
{
        pmap_t pmap = vm_map_pmap(map);

        ledger_debit(pmap->ledger, task_ledgers.iokit_mapped, bytes);
        ledger_debit(pmap->ledger, task_ledgers.phys_footprint, bytes);
}

/* Add (generate) code signature for memory range */
#if CONFIG_DYNAMIC_CODE_SIGNING
kern_return_t
vm_map_sign(vm_map_t map,
    vm_map_offset_t start,
    vm_map_offset_t end)
{
        vm_map_entry_t entry;
        vm_page_t m;
        vm_object_t object;

        /*
         * Vet all the input parameters and current type and state of the
         * underlaying object.  Return with an error if anything is amiss.
         */
        if (map == VM_MAP_NULL) {
                return KERN_INVALID_ARGUMENT;
        }

        vm_map_lock_read(map);

        if (!vm_map_lookup_entry(map, start, &entry) || entry->is_sub_map) {
                /*
                 * Must pass a valid non-submap address.
                 */
                vm_map_unlock_read(map);
                return KERN_INVALID_ADDRESS;
        }

        if ((entry->vme_start > start) || (entry->vme_end < end)) {
                /*
                 * Map entry doesn't cover the requested range. Not handling
                 * this situation currently.
                 */
                vm_map_unlock_read(map);
                return KERN_INVALID_ARGUMENT;
        }

        object = VME_OBJECT(entry);
        if (object == VM_OBJECT_NULL) {
                /*
                 * Object must already be present or we can't sign.
                 */
                vm_map_unlock_read(map);
                return KERN_INVALID_ARGUMENT;
        }

        vm_object_lock(object);
        vm_map_unlock_read(map);

        while (start < end) {
                uint32_t refmod;

                m = vm_page_lookup(object,
                    start - entry->vme_start + VME_OFFSET(entry));
                if (m == VM_PAGE_NULL) {
                        /* shoud we try to fault a page here? we can probably
                         * demand it exists and is locked for this request */
                        vm_object_unlock(object);
                        return KERN_FAILURE;
                }
                /* deal with special page status */
                if (m->vmp_busy ||
                    (m->vmp_unusual && (m->vmp_error || m->vmp_restart || m->vmp_private || m->vmp_absent))) {
                        vm_object_unlock(object);
                        return KERN_FAILURE;
                }

                /* Page is OK... now "validate" it */
                /* This is the place where we'll call out to create a code
                 * directory, later */
                /* XXX TODO4K: deal with 4k subpages individually? */
                m->vmp_cs_validated = VMP_CS_ALL_TRUE;

                /* The page is now "clean" for codesigning purposes. That means
                 * we don't consider it as modified (wpmapped) anymore. But
                 * we'll disconnect the page so we note any future modification
                 * attempts. */
                m->vmp_wpmapped = FALSE;
                refmod = pmap_disconnect(VM_PAGE_GET_PHYS_PAGE(m));

                /* Pull the dirty status from the pmap, since we cleared the
                 * wpmapped bit */
                if ((refmod & VM_MEM_MODIFIED) && !m->vmp_dirty) {
                        SET_PAGE_DIRTY(m, FALSE);
                }

                /* On to the next page */
                start += PAGE_SIZE;
        }
        vm_object_unlock(object);

        return KERN_SUCCESS;
}
#endif

kern_return_t
vm_map_partial_reap(vm_map_t map, unsigned int *reclaimed_resident, unsigned int *reclaimed_compressed)
{
        vm_map_entry_t  entry = VM_MAP_ENTRY_NULL;
        vm_map_entry_t next_entry;
        kern_return_t   kr = KERN_SUCCESS;
        vm_map_t        zap_map;

        vm_map_lock(map);

        /*
         * We use a "zap_map" to avoid having to unlock
         * the "map" in vm_map_delete().
         */
        zap_map = vm_map_create(PMAP_NULL,
            map->min_offset,
            map->max_offset,
            map->hdr.entries_pageable);

        if (zap_map == VM_MAP_NULL) {
                return KERN_RESOURCE_SHORTAGE;
        }

        vm_map_set_page_shift(zap_map,
            VM_MAP_PAGE_SHIFT(map));
        vm_map_disable_hole_optimization(zap_map);

        for (entry = vm_map_first_entry(map);
            entry != vm_map_to_entry(map);
            entry = next_entry) {
                next_entry = entry->vme_next;

                if (VME_OBJECT(entry) &&
                    !entry->is_sub_map &&
                    (VME_OBJECT(entry)->internal == TRUE) &&
                    (VME_OBJECT(entry)->ref_count == 1)) {
                        *reclaimed_resident += VME_OBJECT(entry)->resident_page_count;
                        *reclaimed_compressed += vm_compressor_pager_get_count(VME_OBJECT(entry)->pager);

                        (void)vm_map_delete(map,
                            entry->vme_start,
                            entry->vme_end,
                            VM_MAP_REMOVE_SAVE_ENTRIES,
                            zap_map);
                }
        }

        vm_map_unlock(map);

        /*
         * Get rid of the "zap_maps" and all the map entries that
         * they may still contain.
         */
        if (zap_map != VM_MAP_NULL) {
                vm_map_destroy(zap_map, VM_MAP_REMOVE_NO_PMAP_CLEANUP);
                zap_map = VM_MAP_NULL;
        }

        return kr;
}


#if DEVELOPMENT || DEBUG

int
vm_map_disconnect_page_mappings(
        vm_map_t map,
        boolean_t do_unnest)
{
        vm_map_entry_t entry;
        int     page_count = 0;

        if (do_unnest == TRUE) {
#ifndef NO_NESTED_PMAP
                vm_map_lock(map);

                for (entry = vm_map_first_entry(map);
                    entry != vm_map_to_entry(map);
                    entry = entry->vme_next) {
                        if (entry->is_sub_map && entry->use_pmap) {
                                /*
                                 * Make sure the range between the start of this entry and
                                 * the end of this entry is no longer nested, so that
                                 * we will only remove mappings from the pmap in use by this
                                 * this task
                                 */
                                vm_map_clip_unnest(map, entry, entry->vme_start, entry->vme_end);
                        }
                }
                vm_map_unlock(map);
#endif
        }
        vm_map_lock_read(map);

        page_count = map->pmap->stats.resident_count;

        for (entry = vm_map_first_entry(map);
            entry != vm_map_to_entry(map);
            entry = entry->vme_next) {
                if (!entry->is_sub_map && ((VME_OBJECT(entry) == 0) ||
                    (VME_OBJECT(entry)->phys_contiguous))) {
                        continue;
                }
                if (entry->is_sub_map) {
                        assert(!entry->use_pmap);
                }

                pmap_remove_options(map->pmap, entry->vme_start, entry->vme_end, 0);
        }
        vm_map_unlock_read(map);

        return page_count;
}

kern_return_t
vm_map_inject_error(vm_map_t map, vm_map_offset_t vaddr)
{
        vm_object_t object = NULL;
        vm_object_offset_t offset;
        vm_prot_t prot;
        boolean_t wired;
        vm_map_version_t version;
        vm_map_t real_map;
        int result = KERN_FAILURE;

        vaddr = vm_map_trunc_page(vaddr, PAGE_MASK);
        vm_map_lock(map);

        result = vm_map_lookup_locked(&map, vaddr, VM_PROT_READ,
            OBJECT_LOCK_EXCLUSIVE, &version, &object, &offset, &prot, &wired,
            NULL, &real_map, NULL);
        if (object == NULL) {
                result = KERN_MEMORY_ERROR;
        } else if (object->pager) {
                result = vm_compressor_pager_inject_error(object->pager,
                    offset);
        } else {
                result = KERN_MEMORY_PRESENT;
        }

        if (object != NULL) {
                vm_object_unlock(object);
        }

        if (real_map != map) {
                vm_map_unlock(real_map);
        }
        vm_map_unlock(map);

        return result;
}

#endif


#if CONFIG_FREEZE


extern struct freezer_context freezer_context_global;
AbsoluteTime c_freezer_last_yield_ts = 0;

extern unsigned int memorystatus_freeze_private_shared_pages_ratio;
extern unsigned int memorystatus_freeze_shared_mb_per_process_max;

kern_return_t
vm_map_freeze(
        task_t       task,
        unsigned int *purgeable_count,
        unsigned int *wired_count,
        unsigned int *clean_count,
        unsigned int *dirty_count,
        unsigned int dirty_budget,
        unsigned int *shared_count,
        int          *freezer_error_code,
        boolean_t    eval_only)
{
        vm_map_entry_t  entry2 = VM_MAP_ENTRY_NULL;
        kern_return_t   kr = KERN_SUCCESS;
        boolean_t       evaluation_phase = TRUE;
        vm_object_t     cur_shared_object = NULL;
        int             cur_shared_obj_ref_cnt = 0;
        unsigned int    dirty_private_count = 0, dirty_shared_count = 0, obj_pages_snapshot = 0;

        *purgeable_count = *wired_count = *clean_count = *dirty_count = *shared_count = 0;

        /*
         * We need the exclusive lock here so that we can
         * block any page faults or lookups while we are
         * in the middle of freezing this vm map.
         */
        vm_map_t map = task->map;

        vm_map_lock(map);

        assert(VM_CONFIG_COMPRESSOR_IS_PRESENT);

        if (vm_compressor_low_on_space() || vm_swap_low_on_space()) {
                if (vm_compressor_low_on_space()) {
                        *freezer_error_code = FREEZER_ERROR_NO_COMPRESSOR_SPACE;
                }

                if (vm_swap_low_on_space()) {
                        *freezer_error_code = FREEZER_ERROR_NO_SWAP_SPACE;
                }

                kr = KERN_NO_SPACE;
                goto done;
        }

        if (VM_CONFIG_FREEZER_SWAP_IS_ACTIVE == FALSE) {
                /*
                 * In-memory compressor backing the freezer. No disk.
                 * So no need to do the evaluation phase.
                 */
                evaluation_phase = FALSE;

                if (eval_only == TRUE) {
                        /*
                         * We don't support 'eval_only' mode
                         * in this non-swap config.
                         */
                        *freezer_error_code = FREEZER_ERROR_GENERIC;
                        kr = KERN_INVALID_ARGUMENT;
                        goto done;
                }

                freezer_context_global.freezer_ctx_uncompressed_pages = 0;
                clock_get_uptime(&c_freezer_last_yield_ts);
        }
again:

        for (entry2 = vm_map_first_entry(map);
            entry2 != vm_map_to_entry(map);
            entry2 = entry2->vme_next) {
                vm_object_t     src_object = VME_OBJECT(entry2);

                if (src_object &&
                    !entry2->is_sub_map &&
                    !src_object->phys_contiguous) {
                        /* If eligible, scan the entry, moving eligible pages over to our parent object */

                        if (src_object->internal == TRUE) {
                                if (VM_CONFIG_FREEZER_SWAP_IS_ACTIVE) {
                                        /*
                                         * We skip purgeable objects during evaluation phase only.
                                         * If we decide to freeze this process, we'll explicitly
                                         * purge these objects before we go around again with
                                         * 'evaluation_phase' set to FALSE.
                                         */

                                        if ((src_object->purgable == VM_PURGABLE_EMPTY) || (src_object->purgable == VM_PURGABLE_VOLATILE)) {
                                                /*
                                                 * We want to purge objects that may not belong to this task but are mapped
                                                 * in this task alone. Since we already purged this task's purgeable memory
                                                 * at the end of a successful evaluation phase, we want to avoid doing no-op calls
                                                 * on this task's purgeable objects. Hence the check for only volatile objects.
                                                 */
                                                if (evaluation_phase == FALSE &&
                                                    (src_object->purgable == VM_PURGABLE_VOLATILE) &&
                                                    (src_object->ref_count == 1)) {
                                                        vm_object_lock(src_object);
                                                        vm_object_purge(src_object, 0);
                                                        vm_object_unlock(src_object);
                                                }
                                                continue;
                                        }

                                        /*
                                         * Pages belonging to this object could be swapped to disk.
                                         * Make sure it's not a shared object because we could end
                                         * up just bringing it back in again.
                                         *
                                         * We try to optimize somewhat by checking for objects that are mapped
                                         * more than once within our own map. But we don't do full searches,
                                         * we just look at the entries following our current entry.
                                         */

                                        if (src_object->ref_count > 1) {
                                                if (src_object != cur_shared_object) {
                                                        obj_pages_snapshot = (src_object->resident_page_count - src_object->wired_page_count) + vm_compressor_pager_get_count(src_object->pager);
                                                        dirty_shared_count += obj_pages_snapshot;

                                                        cur_shared_object = src_object;
                                                        cur_shared_obj_ref_cnt = 1;
                                                        continue;
                                                } else {
                                                        cur_shared_obj_ref_cnt++;
                                                        if (src_object->ref_count == cur_shared_obj_ref_cnt) {
                                                                /*
                                                                 * Fall through to below and treat this object as private.
                                                                 * So deduct its pages from our shared total and add it to the
                                                                 * private total.
                                                                 */

                                                                dirty_shared_count -= obj_pages_snapshot;
                                                                dirty_private_count += obj_pages_snapshot;
                                                        } else {
                                                                continue;
                                                        }
                                                }
                                        }


                                        if (src_object->ref_count == 1) {
                                                dirty_private_count += (src_object->resident_page_count - src_object->wired_page_count) + vm_compressor_pager_get_count(src_object->pager);
                                        }

                                        if (evaluation_phase == TRUE) {
                                                continue;
                                        }
                                }

                                uint32_t paged_out_count = vm_object_compressed_freezer_pageout(src_object, dirty_budget);
                                *wired_count += src_object->wired_page_count;

                                if (vm_compressor_low_on_space() || vm_swap_low_on_space()) {
                                        if (vm_compressor_low_on_space()) {
                                                *freezer_error_code = FREEZER_ERROR_NO_COMPRESSOR_SPACE;
                                        }

                                        if (vm_swap_low_on_space()) {
                                                *freezer_error_code = FREEZER_ERROR_NO_SWAP_SPACE;
                                        }

                                        kr = KERN_NO_SPACE;
                                        break;
                                }
                                if (paged_out_count >= dirty_budget) {
                                        break;
                                }
                                dirty_budget -= paged_out_count;
                        }
                }
        }

        *shared_count = (unsigned int) ((dirty_shared_count * PAGE_SIZE_64) / (1024 * 1024ULL));
        if (evaluation_phase) {
                unsigned int shared_pages_threshold = (memorystatus_freeze_shared_mb_per_process_max * 1024 * 1024ULL) / PAGE_SIZE_64;

                if (dirty_shared_count > shared_pages_threshold) {
                        *freezer_error_code = FREEZER_ERROR_EXCESS_SHARED_MEMORY;
                        kr = KERN_FAILURE;
                        goto done;
                }

                if (dirty_shared_count &&
                    ((dirty_private_count / dirty_shared_count) < memorystatus_freeze_private_shared_pages_ratio)) {
                        *freezer_error_code = FREEZER_ERROR_LOW_PRIVATE_SHARED_RATIO;
                        kr = KERN_FAILURE;
                        goto done;
                }

                evaluation_phase = FALSE;
                dirty_shared_count = dirty_private_count = 0;

                freezer_context_global.freezer_ctx_uncompressed_pages = 0;
                clock_get_uptime(&c_freezer_last_yield_ts);

                if (eval_only) {
                        kr = KERN_SUCCESS;
                        goto done;
                }

                vm_purgeable_purge_task_owned(task);

                goto again;
        } else {
                kr = KERN_SUCCESS;
        }

done:
        vm_map_unlock(map);

        if ((eval_only == FALSE) && (kr == KERN_SUCCESS)) {
                vm_object_compressed_freezer_done();
        }
        return kr;
}

#endif

/*
 * vm_map_entry_should_cow_for_true_share:
 *
 * Determines if the map entry should be clipped and setup for copy-on-write
 * to avoid applying "true_share" to a large VM object when only a subset is
 * targeted.
 *
 * For now, we target only the map entries created for the Objective C
 * Garbage Collector, which initially have the following properties:
 *      - alias == VM_MEMORY_MALLOC
 *      - wired_count == 0
 *      - !needs_copy
 * and a VM object with:
 *      - internal
 *      - copy_strategy == MEMORY_OBJECT_COPY_SYMMETRIC
 *      - !true_share
 *      - vo_size == ANON_CHUNK_SIZE
 *
 * Only non-kernel map entries.
 */
boolean_t
vm_map_entry_should_cow_for_true_share(
        vm_map_entry_t  entry)
{
        vm_object_t     object;

        if (entry->is_sub_map) {
                /* entry does not point at a VM object */
                return FALSE;
        }

        if (entry->needs_copy) {
                /* already set for copy_on_write: done! */
                return FALSE;
        }

        if (VME_ALIAS(entry) != VM_MEMORY_MALLOC &&
            VME_ALIAS(entry) != VM_MEMORY_MALLOC_SMALL) {
                /* not a malloc heap or Obj-C Garbage Collector heap */
                return FALSE;
        }

        if (entry->wired_count) {
                /* wired: can't change the map entry... */
                vm_counters.should_cow_but_wired++;
                return FALSE;
        }

        object = VME_OBJECT(entry);

        if (object == VM_OBJECT_NULL) {
                /* no object yet... */
                return FALSE;
        }

        if (!object->internal) {
                /* not an internal object */
                return FALSE;
        }

        if (object->copy_strategy != MEMORY_OBJECT_COPY_SYMMETRIC) {
                /* not the default copy strategy */
                return FALSE;
        }

        if (object->true_share) {
                /* already true_share: too late to avoid it */
                return FALSE;
        }

        if (VME_ALIAS(entry) == VM_MEMORY_MALLOC &&
            object->vo_size != ANON_CHUNK_SIZE) {
                /* ... not an object created for the ObjC Garbage Collector */
                return FALSE;
        }

        if (VME_ALIAS(entry) == VM_MEMORY_MALLOC_SMALL &&
            object->vo_size != 2048 * 4096) {
                /* ... not a "MALLOC_SMALL" heap */
                return FALSE;
        }

        /*
         * All the criteria match: we have a large object being targeted for "true_share".
         * To limit the adverse side-effects linked with "true_share", tell the caller to
         * try and avoid setting up the entire object for "true_share" by clipping the
         * targeted range and setting it up for copy-on-write.
         */
        return TRUE;
}

vm_map_offset_t
vm_map_round_page_mask(
        vm_map_offset_t offset,
        vm_map_offset_t mask)
{
        return VM_MAP_ROUND_PAGE(offset, mask);
}

vm_map_offset_t
vm_map_trunc_page_mask(
        vm_map_offset_t offset,
        vm_map_offset_t mask)
{
        return VM_MAP_TRUNC_PAGE(offset, mask);
}

boolean_t
vm_map_page_aligned(
        vm_map_offset_t offset,
        vm_map_offset_t mask)
{
        return ((offset) & mask) == 0;
}

int
vm_map_page_shift(
        vm_map_t map)
{
        return VM_MAP_PAGE_SHIFT(map);
}

int
vm_map_page_size(
        vm_map_t map)
{
        return VM_MAP_PAGE_SIZE(map);
}

vm_map_offset_t
vm_map_page_mask(
        vm_map_t map)
{
        return VM_MAP_PAGE_MASK(map);
}

kern_return_t
vm_map_set_page_shift(
        vm_map_t        map,
        int             pageshift)
{
        if (map->hdr.nentries != 0) {
                /* too late to change page size */
                return KERN_FAILURE;
        }

        map->hdr.page_shift = pageshift;

        return KERN_SUCCESS;
}

kern_return_t
vm_map_query_volatile(
        vm_map_t        map,
        mach_vm_size_t  *volatile_virtual_size_p,
        mach_vm_size_t  *volatile_resident_size_p,
        mach_vm_size_t  *volatile_compressed_size_p,
        mach_vm_size_t  *volatile_pmap_size_p,
        mach_vm_size_t  *volatile_compressed_pmap_size_p)
{
        mach_vm_size_t  volatile_virtual_size;
        mach_vm_size_t  volatile_resident_count;
        mach_vm_size_t  volatile_compressed_count;
        mach_vm_size_t  volatile_pmap_count;
        mach_vm_size_t  volatile_compressed_pmap_count;
        mach_vm_size_t  resident_count;
        vm_map_entry_t  entry;
        vm_object_t     object;

        /* map should be locked by caller */

        volatile_virtual_size = 0;
        volatile_resident_count = 0;
        volatile_compressed_count = 0;
        volatile_pmap_count = 0;
        volatile_compressed_pmap_count = 0;

        for (entry = vm_map_first_entry(map);
            entry != vm_map_to_entry(map);
            entry = entry->vme_next) {
                mach_vm_size_t  pmap_resident_bytes, pmap_compressed_bytes;

                if (entry->is_sub_map) {
                        continue;
                }
                if (!(entry->protection & VM_PROT_WRITE)) {
                        continue;
                }
                object = VME_OBJECT(entry);
                if (object == VM_OBJECT_NULL) {
                        continue;
                }
                if (object->purgable != VM_PURGABLE_VOLATILE &&
                    object->purgable != VM_PURGABLE_EMPTY) {
                        continue;
                }
                if (VME_OFFSET(entry)) {
                        /*
                         * If the map entry has been split and the object now
                         * appears several times in the VM map, we don't want
                         * to count the object's resident_page_count more than
                         * once.  We count it only for the first one, starting
                         * at offset 0 and ignore the other VM map entries.
                         */
                        continue;
                }
                resident_count = object->resident_page_count;
                if ((VME_OFFSET(entry) / PAGE_SIZE) >= resident_count) {
                        resident_count = 0;
                } else {
                        resident_count -= (VME_OFFSET(entry) / PAGE_SIZE);
                }

                volatile_virtual_size += entry->vme_end - entry->vme_start;
                volatile_resident_count += resident_count;
                if (object->pager) {
                        volatile_compressed_count +=
                            vm_compressor_pager_get_count(object->pager);
                }
                pmap_compressed_bytes = 0;
                pmap_resident_bytes =
                    pmap_query_resident(map->pmap,
                    entry->vme_start,
                    entry->vme_end,
                    &pmap_compressed_bytes);
                volatile_pmap_count += (pmap_resident_bytes / PAGE_SIZE);
                volatile_compressed_pmap_count += (pmap_compressed_bytes
                    / PAGE_SIZE);
        }

        /* map is still locked on return */

        *volatile_virtual_size_p = volatile_virtual_size;
        *volatile_resident_size_p = volatile_resident_count * PAGE_SIZE;
        *volatile_compressed_size_p = volatile_compressed_count * PAGE_SIZE;
        *volatile_pmap_size_p = volatile_pmap_count * PAGE_SIZE;
        *volatile_compressed_pmap_size_p = volatile_compressed_pmap_count * PAGE_SIZE;

        return KERN_SUCCESS;
}

void
vm_map_sizes(vm_map_t map,
    vm_map_size_t * psize,
    vm_map_size_t * pfree,
    vm_map_size_t * plargest_free)
{
        vm_map_entry_t  entry;
        vm_map_offset_t prev;
        vm_map_size_t   free, total_free, largest_free;
        boolean_t       end;

        if (!map) {
                *psize = *pfree = *plargest_free = 0;
                return;
        }
        total_free = largest_free = 0;

        vm_map_lock_read(map);
        if (psize) {
                *psize = map->max_offset - map->min_offset;
        }

        prev = map->min_offset;
        for (entry = vm_map_first_entry(map);; entry = entry->vme_next) {
                end = (entry == vm_map_to_entry(map));

                if (end) {
                        free = entry->vme_end   - prev;
                } else {
                        free = entry->vme_start - prev;
                }

                total_free += free;
                if (free > largest_free) {
                        largest_free = free;
                }

                if (end) {
                        break;
                }
                prev = entry->vme_end;
        }
        vm_map_unlock_read(map);
        if (pfree) {
                *pfree = total_free;
        }
        if (plargest_free) {
                *plargest_free = largest_free;
        }
}

#if VM_SCAN_FOR_SHADOW_CHAIN
int vm_map_shadow_max(vm_map_t map);
int
vm_map_shadow_max(
        vm_map_t map)
{
        int             shadows, shadows_max;
        vm_map_entry_t  entry;
        vm_object_t     object, next_object;

        if (map == NULL) {
                return 0;
        }

        shadows_max = 0;

        vm_map_lock_read(map);

        for (entry = vm_map_first_entry(map);
            entry != vm_map_to_entry(map);
            entry = entry->vme_next) {
                if (entry->is_sub_map) {
                        continue;
                }
                object = VME_OBJECT(entry);
                if (object == NULL) {
                        continue;
                }
                vm_object_lock_shared(object);
                for (shadows = 0;
                    object->shadow != NULL;
                    shadows++, object = next_object) {
                        next_object = object->shadow;
                        vm_object_lock_shared(next_object);
                        vm_object_unlock(object);
                }
                vm_object_unlock(object);
                if (shadows > shadows_max) {
                        shadows_max = shadows;
                }
        }

        vm_map_unlock_read(map);

        return shadows_max;
}
#endif /* VM_SCAN_FOR_SHADOW_CHAIN */

void
vm_commit_pagezero_status(vm_map_t lmap)
{
        pmap_advise_pagezero_range(lmap->pmap, lmap->min_offset);
}

#if XNU_TARGET_OS_OSX
void
vm_map_set_high_start(
        vm_map_t        map,
        vm_map_offset_t high_start)
{
        map->vmmap_high_start = high_start;
}
#endif /* XNU_TARGET_OS_OSX */


/*
 * FORKED CORPSE FOOTPRINT
 *
 * A forked corpse gets a copy of the original VM map but its pmap is mostly
 * empty since it never ran and never got to fault in any pages.
 * Collecting footprint info (via "sysctl vm.self_region_footprint") for
 * a forked corpse would therefore return very little information.
 *
 * When forking a corpse, we can pass the VM_MAP_FORK_CORPSE_FOOTPRINT option
 * to vm_map_fork() to collect footprint information from the original VM map
 * and its pmap, and store it in the forked corpse's VM map.  That information
 * is stored in place of the VM map's "hole list" since we'll never need to
 * lookup for holes in the corpse's map.
 *
 * The corpse's footprint info looks like this:
 *
 * vm_map->vmmap_corpse_footprint points to pageable kernel memory laid out
 * as follows:
 *                     +---------------------------------------+
 *            header-> | cf_size                               |
 *                     +-------------------+-------------------+
 *                     | cf_last_region    | cf_last_zeroes    |
 *                     +-------------------+-------------------+
 *           region1-> | cfr_vaddr                             |
 *                     +-------------------+-------------------+
 *                     | cfr_num_pages     | d0 | d1 | d2 | d3 |
 *                     +---------------------------------------+
 *                     | d4 | d5 | ...                         |
 *                     +---------------------------------------+
 *                     | ...                                   |
 *                     +-------------------+-------------------+
 *                     | dy | dz | na | na | cfr_vaddr...      | <-region2
 *                     +-------------------+-------------------+
 *                     | cfr_vaddr (ctd)   | cfr_num_pages     |
 *                     +---------------------------------------+
 *                     | d0 | d1 ...                           |
 *                     +---------------------------------------+
 *                       ...
 *                     +---------------------------------------+
 *       last region-> | cfr_vaddr                             |
 *                     +---------------------------------------+
 *                     + cfr_num_pages     | d0 | d1 | d2 | d3 |
 *                     +---------------------------------------+
 *                       ...
 *                     +---------------------------------------+
 *                     | dx | dy | dz | na | na | na | na | na |
 *                     +---------------------------------------+
 *
 * where:
 *      cf_size:        total size of the buffer (rounded to page size)
 *      cf_last_region: offset in the buffer of the last "region" sub-header
 *      cf_last_zeroes: number of trailing "zero" dispositions at the end
 *                      of last region
 *      cfr_vaddr:      virtual address of the start of the covered "region"
 *      cfr_num_pages:  number of pages in the covered "region"
 *      d*:             disposition of the page at that virtual address
 * Regions in the buffer are word-aligned.
 *
 * We estimate the size of the buffer based on the number of memory regions
 * and the virtual size of the address space.  While copying each memory region
 * during vm_map_fork(), we also collect the footprint info for that region
 * and store it in the buffer, packing it as much as possible (coalescing
 * contiguous memory regions to avoid having too many region headers and
 * avoiding long streaks of "zero" page dispositions by splitting footprint
 * "regions", so the number of regions in the footprint buffer might not match
 * the number of memory regions in the address space.
 *
 * We also have to copy the original task's "nonvolatile" ledgers since that's
 * part of the footprint and will need to be reported to any tool asking for
 * the footprint information of the forked corpse.
 */

uint64_t vm_map_corpse_footprint_count = 0;
uint64_t vm_map_corpse_footprint_size_avg = 0;
uint64_t vm_map_corpse_footprint_size_max = 0;
uint64_t vm_map_corpse_footprint_full = 0;
uint64_t vm_map_corpse_footprint_no_buf = 0;

struct vm_map_corpse_footprint_header {
        vm_size_t       cf_size;        /* allocated buffer size */
        uint32_t        cf_last_region; /* offset of last region in buffer */
        union {
                uint32_t cfu_last_zeroes; /* during creation:
                                           * number of "zero" dispositions at
                                           * end of last region */
                uint32_t cfu_hint_region; /* during lookup:
                                           * offset of last looked up region */
#define cf_last_zeroes cfu.cfu_last_zeroes
#define cf_hint_region cfu.cfu_hint_region
        } cfu;
};
typedef uint8_t cf_disp_t;
struct vm_map_corpse_footprint_region {
        vm_map_offset_t cfr_vaddr;      /* region start virtual address */
        uint32_t        cfr_num_pages;  /* number of pages in this "region" */
        cf_disp_t   cfr_disposition[0]; /* disposition of each page */
} __attribute__((packed));

static cf_disp_t
vm_page_disposition_to_cf_disp(
        int disposition)
{
        assert(sizeof(cf_disp_t) == 1);
        /* relocate bits that don't fit in a "uint8_t" */
        if (disposition & VM_PAGE_QUERY_PAGE_REUSABLE) {
                disposition |= VM_PAGE_QUERY_PAGE_FICTITIOUS;
        }
        /* cast gets rid of extra bits */
        return (cf_disp_t) disposition;
}

static int
vm_page_cf_disp_to_disposition(
        cf_disp_t cf_disp)
{
        int disposition;

        assert(sizeof(cf_disp_t) == 1);
        disposition = (int) cf_disp;
        /* move relocated bits back in place */
        if (cf_disp & VM_PAGE_QUERY_PAGE_FICTITIOUS) {
                disposition |= VM_PAGE_QUERY_PAGE_REUSABLE;
                disposition &= ~VM_PAGE_QUERY_PAGE_FICTITIOUS;
        }
        return disposition;
}

/*
 * vm_map_corpse_footprint_new_region:
 *      closes the current footprint "region" and creates a new one
 *
 * Returns NULL if there's not enough space in the buffer for a new region.
 */
static struct vm_map_corpse_footprint_region *
vm_map_corpse_footprint_new_region(
        struct vm_map_corpse_footprint_header *footprint_header)
{
        uintptr_t       footprint_edge;
        uint32_t        new_region_offset;
        struct vm_map_corpse_footprint_region *footprint_region;
        struct vm_map_corpse_footprint_region *new_footprint_region;

        footprint_edge = ((uintptr_t)footprint_header +
            footprint_header->cf_size);
        footprint_region = ((struct vm_map_corpse_footprint_region *)
            ((char *)footprint_header +
            footprint_header->cf_last_region));
        assert((uintptr_t)footprint_region + sizeof(*footprint_region) <=
            footprint_edge);

        /* get rid of trailing zeroes in the last region */
        assert(footprint_region->cfr_num_pages >=
            footprint_header->cf_last_zeroes);
        footprint_region->cfr_num_pages -=
            footprint_header->cf_last_zeroes;
        footprint_header->cf_last_zeroes = 0;

        /* reuse this region if it's now empty */
        if (footprint_region->cfr_num_pages == 0) {
                return footprint_region;
        }

        /* compute offset of new region */
        new_region_offset = footprint_header->cf_last_region;
        new_region_offset += sizeof(*footprint_region);
        new_region_offset += (footprint_region->cfr_num_pages * sizeof(cf_disp_t));
        new_region_offset = roundup(new_region_offset, sizeof(int));

        /* check if we're going over the edge */
        if (((uintptr_t)footprint_header +
            new_region_offset +
            sizeof(*footprint_region)) >=
            footprint_edge) {
                /* over the edge: no new region */
                return NULL;
        }

        /* adjust offset of last region in header */
        footprint_header->cf_last_region = new_region_offset;

        new_footprint_region = (struct vm_map_corpse_footprint_region *)
            ((char *)footprint_header +
            footprint_header->cf_last_region);
        new_footprint_region->cfr_vaddr = 0;
        new_footprint_region->cfr_num_pages = 0;
        /* caller needs to initialize new region */

        return new_footprint_region;
}

/*
 * vm_map_corpse_footprint_collect:
 *      collect footprint information for "old_entry" in "old_map" and
 *      stores it in "new_map"'s vmmap_footprint_info.
 */
kern_return_t
vm_map_corpse_footprint_collect(
        vm_map_t        old_map,
        vm_map_entry_t  old_entry,
        vm_map_t        new_map)
{
        vm_map_offset_t va;
        kern_return_t   kr;
        struct vm_map_corpse_footprint_header *footprint_header;
        struct vm_map_corpse_footprint_region *footprint_region;
        struct vm_map_corpse_footprint_region *new_footprint_region;
        cf_disp_t       *next_disp_p;
        uintptr_t       footprint_edge;
        uint32_t        num_pages_tmp;
        int             effective_page_size;

        effective_page_size = MIN(PAGE_SIZE, VM_MAP_PAGE_SIZE(old_map));

        va = old_entry->vme_start;

        vm_map_lock_assert_exclusive(old_map);
        vm_map_lock_assert_exclusive(new_map);

        assert(new_map->has_corpse_footprint);
        assert(!old_map->has_corpse_footprint);
        if (!new_map->has_corpse_footprint ||
            old_map->has_corpse_footprint) {
                /*
                 * This can only transfer footprint info from a
                 * map with a live pmap to a map with a corpse footprint.
                 */
                return KERN_NOT_SUPPORTED;
        }

        if (new_map->vmmap_corpse_footprint == NULL) {
                vm_offset_t     buf;
                vm_size_t       buf_size;

                buf = 0;
                buf_size = (sizeof(*footprint_header) +
                    (old_map->hdr.nentries
                    *
                    (sizeof(*footprint_region) +
                    +3))            /* potential alignment for each region */
                    +
                    ((old_map->size / effective_page_size)
                    *
                    sizeof(cf_disp_t)));      /* disposition for each page */
//              printf("FBDP corpse map %p guestimate footprint size 0x%llx\n", new_map, (uint64_t) buf_size);
                buf_size = round_page(buf_size);

                /* limit buffer to 1 page to validate overflow detection */
//              buf_size = PAGE_SIZE;

                /* limit size to a somewhat sane amount */
#if XNU_TARGET_OS_OSX
#define VM_MAP_CORPSE_FOOTPRINT_INFO_MAX_SIZE   (8*1024*1024)   /* 8MB */
#else /* XNU_TARGET_OS_OSX */
#define VM_MAP_CORPSE_FOOTPRINT_INFO_MAX_SIZE   (256*1024)      /* 256KB */
#endif /* XNU_TARGET_OS_OSX */
                if (buf_size > VM_MAP_CORPSE_FOOTPRINT_INFO_MAX_SIZE) {
                        buf_size = VM_MAP_CORPSE_FOOTPRINT_INFO_MAX_SIZE;
                }

                /*
                 * Allocate the pageable buffer (with a trailing guard page).
                 * It will be zero-filled on demand.
                 */
                kr = kernel_memory_allocate(kernel_map,
                    &buf,
                    (buf_size
                    + PAGE_SIZE),                          /* trailing guard page */
                    0,                         /* mask */
                    KMA_PAGEABLE | KMA_GUARD_LAST,
                    VM_KERN_MEMORY_DIAG);
                if (kr != KERN_SUCCESS) {
                        vm_map_corpse_footprint_no_buf++;
                        return kr;
                }

                /* initialize header and 1st region */
                footprint_header = (struct vm_map_corpse_footprint_header *)buf;
                new_map->vmmap_corpse_footprint = footprint_header;

                footprint_header->cf_size = buf_size;
                footprint_header->cf_last_region =
                    sizeof(*footprint_header);
                footprint_header->cf_last_zeroes = 0;

                footprint_region = (struct vm_map_corpse_footprint_region *)
                    ((char *)footprint_header +
                    footprint_header->cf_last_region);
                footprint_region->cfr_vaddr = 0;
                footprint_region->cfr_num_pages = 0;
        } else {
                /* retrieve header and last region */
                footprint_header = (struct vm_map_corpse_footprint_header *)
                    new_map->vmmap_corpse_footprint;
                footprint_region = (struct vm_map_corpse_footprint_region *)
                    ((char *)footprint_header +
                    footprint_header->cf_last_region);
        }
        footprint_edge = ((uintptr_t)footprint_header +
            footprint_header->cf_size);

        if ((footprint_region->cfr_vaddr +
            (((vm_map_offset_t)footprint_region->cfr_num_pages) *
            effective_page_size))
            != old_entry->vme_start) {
                uint64_t num_pages_delta, num_pages_delta_size;
                uint32_t region_offset_delta_size;

                /*
                 * Not the next contiguous virtual address:
                 * start a new region or store "zero" dispositions for
                 * the missing pages?
                 */
                /* size of gap in actual page dispositions */
                num_pages_delta = ((old_entry->vme_start -
                    footprint_region->cfr_vaddr) / effective_page_size)
                    - footprint_region->cfr_num_pages;
                num_pages_delta_size = num_pages_delta * sizeof(cf_disp_t);
                /* size of gap as a new footprint region header */
                region_offset_delta_size =
                    (sizeof(*footprint_region) +
                    roundup(((footprint_region->cfr_num_pages -
                    footprint_header->cf_last_zeroes) * sizeof(cf_disp_t)),
                    sizeof(int)) -
                    ((footprint_region->cfr_num_pages -
                    footprint_header->cf_last_zeroes) * sizeof(cf_disp_t)));
//              printf("FBDP %s:%d region 0x%x 0x%llx 0x%x vme_start 0x%llx pages_delta 0x%llx region_delta 0x%x\n", __FUNCTION__, __LINE__, footprint_header->cf_last_region, footprint_region->cfr_vaddr, footprint_region->cfr_num_pages, old_entry->vme_start, num_pages_delta, region_offset_delta);
                if (region_offset_delta_size < num_pages_delta_size ||
                    os_add3_overflow(footprint_region->cfr_num_pages,
                    (uint32_t) num_pages_delta,
                    1,
                    &num_pages_tmp)) {
                        /*
                         * Storing data for this gap would take more space
                         * than inserting a new footprint region header:
                         * let's start a new region and save space. If it's a
                         * tie, let's avoid using a new region, since that
                         * would require more region hops to find the right
                         * range during lookups.
                         *
                         * If the current region's cfr_num_pages would overflow
                         * if we added "zero" page dispositions for the gap,
                         * no choice but to start a new region.
                         */
//                      printf("FBDP %s:%d new region\n", __FUNCTION__, __LINE__);
                        new_footprint_region =
                            vm_map_corpse_footprint_new_region(footprint_header);
                        /* check that we're not going over the edge */
                        if (new_footprint_region == NULL) {
                                goto over_the_edge;
                        }
                        footprint_region = new_footprint_region;
                        /* initialize new region as empty */
                        footprint_region->cfr_vaddr = old_entry->vme_start;
                        footprint_region->cfr_num_pages = 0;
                } else {
                        /*
                         * Store "zero" page dispositions for the missing
                         * pages.
                         */
//                      printf("FBDP %s:%d zero gap\n", __FUNCTION__, __LINE__);
                        for (; num_pages_delta > 0; num_pages_delta--) {
                                next_disp_p = (cf_disp_t *)
                                    ((uintptr_t) footprint_region +
                                    sizeof(*footprint_region));
                                next_disp_p += footprint_region->cfr_num_pages;
                                /* check that we're not going over the edge */
                                if ((uintptr_t)next_disp_p >= footprint_edge) {
                                        goto over_the_edge;
                                }
                                /* store "zero" disposition for this gap page */
                                footprint_region->cfr_num_pages++;
                                *next_disp_p = (cf_disp_t) 0;
                                footprint_header->cf_last_zeroes++;
                        }
                }
        }

        for (va = old_entry->vme_start;
            va < old_entry->vme_end;
            va += effective_page_size) {
                int             disposition;
                cf_disp_t       cf_disp;

                vm_map_footprint_query_page_info(old_map,
                    old_entry,
                    va,
                    &disposition);
                cf_disp = vm_page_disposition_to_cf_disp(disposition);

//              if (va < SHARED_REGION_BASE_ARM64) printf("FBDP collect map %p va 0x%llx disp 0x%x\n", new_map, va, disp);

                if (cf_disp == 0 && footprint_region->cfr_num_pages == 0) {
                        /*
                         * Ignore "zero" dispositions at start of
                         * region: just move start of region.
                         */
                        footprint_region->cfr_vaddr += effective_page_size;
                        continue;
                }

                /* would region's cfr_num_pages overflow? */
                if (os_add_overflow(footprint_region->cfr_num_pages, 1,
                    &num_pages_tmp)) {
                        /* overflow: create a new region */
                        new_footprint_region =
                            vm_map_corpse_footprint_new_region(
                                footprint_header);
                        if (new_footprint_region == NULL) {
                                goto over_the_edge;
                        }
                        footprint_region = new_footprint_region;
                        footprint_region->cfr_vaddr = va;
                        footprint_region->cfr_num_pages = 0;
                }

                next_disp_p = (cf_disp_t *) ((uintptr_t) footprint_region +
                    sizeof(*footprint_region));
                next_disp_p += footprint_region->cfr_num_pages;
                /* check that we're not going over the edge */
                if ((uintptr_t)next_disp_p >= footprint_edge) {
                        goto over_the_edge;
                }
                /* store this dispostion */
                *next_disp_p = cf_disp;
                footprint_region->cfr_num_pages++;

                if (cf_disp != 0) {
                        /* non-zero disp: break the current zero streak */
                        footprint_header->cf_last_zeroes = 0;
                        /* done */
                        continue;
                }

                /* zero disp: add to the current streak of zeroes */
                footprint_header->cf_last_zeroes++;
                if ((footprint_header->cf_last_zeroes +
                    roundup(((footprint_region->cfr_num_pages -
                    footprint_header->cf_last_zeroes) * sizeof(cf_disp_t)) &
                    (sizeof(int) - 1),
                    sizeof(int))) <
                    (sizeof(*footprint_header))) {
                        /*
                         * There are not enough trailing "zero" dispositions
                         * (+ the extra padding we would need for the previous
                         * region); creating a new region would not save space
                         * at this point, so let's keep this "zero" disposition
                         * in this region and reconsider later.
                         */
                        continue;
                }
                /*
                 * Create a new region to avoid having too many consecutive
                 * "zero" dispositions.
                 */
                new_footprint_region =
                    vm_map_corpse_footprint_new_region(footprint_header);
                if (new_footprint_region == NULL) {
                        goto over_the_edge;
                }
                footprint_region = new_footprint_region;
                /* initialize the new region as empty ... */
                footprint_region->cfr_num_pages = 0;
                /* ... and skip this "zero" disp */
                footprint_region->cfr_vaddr = va + effective_page_size;
        }

        return KERN_SUCCESS;

over_the_edge:
//      printf("FBDP map %p footprint was full for va 0x%llx\n", new_map, va);
        vm_map_corpse_footprint_full++;
        return KERN_RESOURCE_SHORTAGE;
}

/*
 * vm_map_corpse_footprint_collect_done:
 *      completes the footprint collection by getting rid of any remaining
 *      trailing "zero" dispositions and trimming the unused part of the
 *      kernel buffer
 */
void
vm_map_corpse_footprint_collect_done(
        vm_map_t        new_map)
{
        struct vm_map_corpse_footprint_header *footprint_header;
        struct vm_map_corpse_footprint_region *footprint_region;
        vm_size_t       buf_size, actual_size;
        kern_return_t   kr;

        assert(new_map->has_corpse_footprint);
        if (!new_map->has_corpse_footprint ||
            new_map->vmmap_corpse_footprint == NULL) {
                return;
        }

        footprint_header = (struct vm_map_corpse_footprint_header *)
            new_map->vmmap_corpse_footprint;
        buf_size = footprint_header->cf_size;

        footprint_region = (struct vm_map_corpse_footprint_region *)
            ((char *)footprint_header +
            footprint_header->cf_last_region);

        /* get rid of trailing zeroes in last region */
        assert(footprint_region->cfr_num_pages >= footprint_header->cf_last_zeroes);
        footprint_region->cfr_num_pages -= footprint_header->cf_last_zeroes;
        footprint_header->cf_last_zeroes = 0;

        actual_size = (vm_size_t)(footprint_header->cf_last_region +
            sizeof(*footprint_region) +
            (footprint_region->cfr_num_pages * sizeof(cf_disp_t)));

//      printf("FBDP map %p buf_size 0x%llx actual_size 0x%llx\n", new_map, (uint64_t) buf_size, (uint64_t) actual_size);
        vm_map_corpse_footprint_size_avg =
            (((vm_map_corpse_footprint_size_avg *
            vm_map_corpse_footprint_count) +
            actual_size) /
            (vm_map_corpse_footprint_count + 1));
        vm_map_corpse_footprint_count++;
        if (actual_size > vm_map_corpse_footprint_size_max) {
                vm_map_corpse_footprint_size_max = actual_size;
        }

        actual_size = round_page(actual_size);
        if (buf_size > actual_size) {
                kr = vm_deallocate(kernel_map,
                    ((vm_address_t)footprint_header +
                    actual_size +
                    PAGE_SIZE),                 /* trailing guard page */
                    (buf_size - actual_size));
                assertf(kr == KERN_SUCCESS,
                    "trim: footprint_header %p buf_size 0x%llx actual_size 0x%llx kr=0x%x\n",
                    footprint_header,
                    (uint64_t) buf_size,
                    (uint64_t) actual_size,
                    kr);
                kr = vm_protect(kernel_map,
                    ((vm_address_t)footprint_header +
                    actual_size),
                    PAGE_SIZE,
                    FALSE,             /* set_maximum */
                    VM_PROT_NONE);
                assertf(kr == KERN_SUCCESS,
                    "guard: footprint_header %p buf_size 0x%llx actual_size 0x%llx kr=0x%x\n",
                    footprint_header,
                    (uint64_t) buf_size,
                    (uint64_t) actual_size,
                    kr);
        }

        footprint_header->cf_size = actual_size;
}

/*
 * vm_map_corpse_footprint_query_page_info:
 *      retrieves the disposition of the page at virtual address "vaddr"
 *      in the forked corpse's VM map
 *
 * This is the equivalent of vm_map_footprint_query_page_info() for a forked corpse.
 */
kern_return_t
vm_map_corpse_footprint_query_page_info(
        vm_map_t        map,
        vm_map_offset_t va,
        int             *disposition_p)
{
        struct vm_map_corpse_footprint_header *footprint_header;
        struct vm_map_corpse_footprint_region *footprint_region;
        uint32_t        footprint_region_offset;
        vm_map_offset_t region_start, region_end;
        int             disp_idx;
        kern_return_t   kr;
        int             effective_page_size;
        cf_disp_t       cf_disp;

        if (!map->has_corpse_footprint) {
                *disposition_p = 0;
                kr = KERN_INVALID_ARGUMENT;
                goto done;
        }

        footprint_header = map->vmmap_corpse_footprint;
        if (footprint_header == NULL) {
                *disposition_p = 0;
//              if (va < SHARED_REGION_BASE_ARM64) printf("FBDP %d query map %p va 0x%llx disp 0x%x\n", __LINE__, map, va, *disposition_p);
                kr = KERN_INVALID_ARGUMENT;
                goto done;
        }

        /* start looking at the hint ("cf_hint_region") */
        footprint_region_offset = footprint_header->cf_hint_region;

        effective_page_size = MIN(PAGE_SIZE, VM_MAP_PAGE_SIZE(map));

lookup_again:
        if (footprint_region_offset < sizeof(*footprint_header)) {
                /* hint too low: start from 1st region */
                footprint_region_offset = sizeof(*footprint_header);
        }
        if (footprint_region_offset >= footprint_header->cf_last_region) {
                /* hint too high: re-start from 1st region */
                footprint_region_offset = sizeof(*footprint_header);
        }
        footprint_region = (struct vm_map_corpse_footprint_region *)
            ((char *)footprint_header + footprint_region_offset);
        region_start = footprint_region->cfr_vaddr;
        region_end = (region_start +
            ((vm_map_offset_t)(footprint_region->cfr_num_pages) *
            effective_page_size));
        if (va < region_start &&
            footprint_region_offset != sizeof(*footprint_header)) {
                /* our range starts before the hint region */

                /* reset the hint (in a racy way...) */
                footprint_header->cf_hint_region = sizeof(*footprint_header);
                /* lookup "va" again from 1st region */
                footprint_region_offset = sizeof(*footprint_header);
                goto lookup_again;
        }

        while (va >= region_end) {
                if (footprint_region_offset >= footprint_header->cf_last_region) {
                        break;
                }
                /* skip the region's header */
                footprint_region_offset += sizeof(*footprint_region);
                /* skip the region's page dispositions */
                footprint_region_offset += (footprint_region->cfr_num_pages * sizeof(cf_disp_t));
                /* align to next word boundary */
                footprint_region_offset =
                    roundup(footprint_region_offset,
                    sizeof(int));
                footprint_region = (struct vm_map_corpse_footprint_region *)
                    ((char *)footprint_header + footprint_region_offset);
                region_start = footprint_region->cfr_vaddr;
                region_end = (region_start +
                    ((vm_map_offset_t)(footprint_region->cfr_num_pages) *
                    effective_page_size));
        }
        if (va < region_start || va >= region_end) {
                /* page not found */
                *disposition_p = 0;
//              if (va < SHARED_REGION_BASE_ARM64) printf("FBDP %d query map %p va 0x%llx disp 0x%x\n", __LINE__, map, va, *disposition_p);
                kr = KERN_SUCCESS;
                goto done;
        }

        /* "va" found: set the lookup hint for next lookup (in a racy way...) */
        footprint_header->cf_hint_region = footprint_region_offset;

        /* get page disposition for "va" in this region */
        disp_idx = (int) ((va - footprint_region->cfr_vaddr) / effective_page_size);
        cf_disp = footprint_region->cfr_disposition[disp_idx];
        *disposition_p = vm_page_cf_disp_to_disposition(cf_disp);
        kr = KERN_SUCCESS;
done:
//      if (va < SHARED_REGION_BASE_ARM64) printf("FBDP %d query map %p va 0x%llx disp 0x%x\n", __LINE__, map, va, *disposition_p);
        /* dtrace -n 'vminfo:::footprint_query_page_info { printf("map 0x%p va 0x%llx disp 0x%x kr 0x%x", arg0, arg1, arg2, arg3); }' */
        DTRACE_VM4(footprint_query_page_info,
            vm_map_t, map,
            vm_map_offset_t, va,
            int, *disposition_p,
            kern_return_t, kr);

        return kr;
}

void
vm_map_corpse_footprint_destroy(
        vm_map_t        map)
{
        if (map->has_corpse_footprint &&
            map->vmmap_corpse_footprint != 0) {
                struct vm_map_corpse_footprint_header *footprint_header;
                vm_size_t buf_size;
                kern_return_t kr;

                footprint_header = map->vmmap_corpse_footprint;
                buf_size = footprint_header->cf_size;
                kr = vm_deallocate(kernel_map,
                    (vm_offset_t) map->vmmap_corpse_footprint,
                    ((vm_size_t) buf_size
                    + PAGE_SIZE));                 /* trailing guard page */
                assertf(kr == KERN_SUCCESS, "kr=0x%x\n", kr);
                map->vmmap_corpse_footprint = 0;
                map->has_corpse_footprint = FALSE;
        }
}

/*
 * vm_map_copy_footprint_ledgers:
 *      copies any ledger that's relevant to the memory footprint of "old_task"
 *      into the forked corpse's task ("new_task")
 */
void
vm_map_copy_footprint_ledgers(
        task_t  old_task,
        task_t  new_task)
{
        vm_map_copy_ledger(old_task, new_task, task_ledgers.phys_footprint);
        vm_map_copy_ledger(old_task, new_task, task_ledgers.purgeable_nonvolatile);
        vm_map_copy_ledger(old_task, new_task, task_ledgers.purgeable_nonvolatile_compressed);
        vm_map_copy_ledger(old_task, new_task, task_ledgers.internal);
        vm_map_copy_ledger(old_task, new_task, task_ledgers.internal_compressed);
        vm_map_copy_ledger(old_task, new_task, task_ledgers.iokit_mapped);
        vm_map_copy_ledger(old_task, new_task, task_ledgers.alternate_accounting);
        vm_map_copy_ledger(old_task, new_task, task_ledgers.alternate_accounting_compressed);
        vm_map_copy_ledger(old_task, new_task, task_ledgers.page_table);
        vm_map_copy_ledger(old_task, new_task, task_ledgers.tagged_footprint);
        vm_map_copy_ledger(old_task, new_task, task_ledgers.tagged_footprint_compressed);
        vm_map_copy_ledger(old_task, new_task, task_ledgers.network_nonvolatile);
        vm_map_copy_ledger(old_task, new_task, task_ledgers.network_nonvolatile_compressed);
        vm_map_copy_ledger(old_task, new_task, task_ledgers.media_footprint);
        vm_map_copy_ledger(old_task, new_task, task_ledgers.media_footprint_compressed);
        vm_map_copy_ledger(old_task, new_task, task_ledgers.graphics_footprint);
        vm_map_copy_ledger(old_task, new_task, task_ledgers.graphics_footprint_compressed);
        vm_map_copy_ledger(old_task, new_task, task_ledgers.neural_footprint);
        vm_map_copy_ledger(old_task, new_task, task_ledgers.neural_footprint_compressed);
        vm_map_copy_ledger(old_task, new_task, task_ledgers.wired_mem);
}

/*
 * vm_map_copy_ledger:
 *      copy a single ledger from "old_task" to "new_task"
 */
void
vm_map_copy_ledger(
        task_t  old_task,
        task_t  new_task,
        int     ledger_entry)
{
        ledger_amount_t old_balance, new_balance, delta;

        assert(new_task->map->has_corpse_footprint);
        if (!new_task->map->has_corpse_footprint) {
                return;
        }

        /* turn off sanity checks for the ledger we're about to mess with */
        ledger_disable_panic_on_negative(new_task->ledger,
            ledger_entry);

        /* adjust "new_task" to match "old_task" */
        ledger_get_balance(old_task->ledger,
            ledger_entry,
            &old_balance);
        ledger_get_balance(new_task->ledger,
            ledger_entry,
            &new_balance);
        if (new_balance == old_balance) {
                /* new == old: done */
        } else if (new_balance > old_balance) {
                /* new > old ==> new -= new - old */
                delta = new_balance - old_balance;
                ledger_debit(new_task->ledger,
                    ledger_entry,
                    delta);
        } else {
                /* new < old ==> new += old - new */
                delta = old_balance - new_balance;
                ledger_credit(new_task->ledger,
                    ledger_entry,
                    delta);
        }
}

#if MACH_ASSERT

extern int pmap_ledgers_panic;
extern int pmap_ledgers_panic_leeway;

#define LEDGER_DRIFT(__LEDGER)                    \
        int             __LEDGER##_over;          \
        ledger_amount_t __LEDGER##_over_total;    \
        ledger_amount_t __LEDGER##_over_max;      \
        int             __LEDGER##_under;         \
        ledger_amount_t __LEDGER##_under_total;   \
        ledger_amount_t __LEDGER##_under_max

struct {
        uint64_t        num_pmaps_checked;

        LEDGER_DRIFT(phys_footprint);
        LEDGER_DRIFT(internal);
        LEDGER_DRIFT(internal_compressed);
        LEDGER_DRIFT(iokit_mapped);
        LEDGER_DRIFT(alternate_accounting);
        LEDGER_DRIFT(alternate_accounting_compressed);
        LEDGER_DRIFT(page_table);
        LEDGER_DRIFT(purgeable_volatile);
        LEDGER_DRIFT(purgeable_nonvolatile);
        LEDGER_DRIFT(purgeable_volatile_compressed);
        LEDGER_DRIFT(purgeable_nonvolatile_compressed);
        LEDGER_DRIFT(tagged_nofootprint);
        LEDGER_DRIFT(tagged_footprint);
        LEDGER_DRIFT(tagged_nofootprint_compressed);
        LEDGER_DRIFT(tagged_footprint_compressed);
        LEDGER_DRIFT(network_volatile);
        LEDGER_DRIFT(network_nonvolatile);
        LEDGER_DRIFT(network_volatile_compressed);
        LEDGER_DRIFT(network_nonvolatile_compressed);
        LEDGER_DRIFT(media_nofootprint);
        LEDGER_DRIFT(media_footprint);
        LEDGER_DRIFT(media_nofootprint_compressed);
        LEDGER_DRIFT(media_footprint_compressed);
        LEDGER_DRIFT(graphics_nofootprint);
        LEDGER_DRIFT(graphics_footprint);
        LEDGER_DRIFT(graphics_nofootprint_compressed);
        LEDGER_DRIFT(graphics_footprint_compressed);
        LEDGER_DRIFT(neural_nofootprint);
        LEDGER_DRIFT(neural_footprint);
        LEDGER_DRIFT(neural_nofootprint_compressed);
        LEDGER_DRIFT(neural_footprint_compressed);
} pmap_ledgers_drift;

void
vm_map_pmap_check_ledgers(
        pmap_t          pmap,
        ledger_t        ledger,
        int             pid,
        char            *procname)
{
        ledger_amount_t bal;
        boolean_t       do_panic;

        do_panic = FALSE;

        pmap_ledgers_drift.num_pmaps_checked++;

#define LEDGER_CHECK_BALANCE(__LEDGER)                                  \
MACRO_BEGIN                                                             \
        int panic_on_negative = TRUE;                                   \
        ledger_get_balance(ledger,                                      \
                           task_ledgers.__LEDGER,                       \
                           &bal);                                       \
        ledger_get_panic_on_negative(ledger,                            \
                                     task_ledgers.__LEDGER,             \
                                     &panic_on_negative);               \
        if (bal != 0) {                                                 \
                if (panic_on_negative ||                                \
                    (pmap_ledgers_panic &&                              \
                     pmap_ledgers_panic_leeway > 0 &&                   \
                     (bal > (pmap_ledgers_panic_leeway * PAGE_SIZE) ||  \
                      bal < (-pmap_ledgers_panic_leeway * PAGE_SIZE)))) { \
                        do_panic = TRUE;                                \
                }                                                       \
                printf("LEDGER BALANCE proc %d (%s) "                   \
                       "\"%s\" = %lld\n",                               \
                       pid, procname, #__LEDGER, bal);                  \
                if (bal > 0) {                                          \
                        pmap_ledgers_drift.__LEDGER##_over++;           \
                        pmap_ledgers_drift.__LEDGER##_over_total += bal; \
                        if (bal > pmap_ledgers_drift.__LEDGER##_over_max) { \
                                pmap_ledgers_drift.__LEDGER##_over_max = bal; \
                        }                                               \
                } else if (bal < 0) {                                   \
                        pmap_ledgers_drift.__LEDGER##_under++;          \
                        pmap_ledgers_drift.__LEDGER##_under_total += bal; \
                        if (bal < pmap_ledgers_drift.__LEDGER##_under_max) { \
                                pmap_ledgers_drift.__LEDGER##_under_max = bal; \
                        }                                               \
                }                                                       \
        }                                                               \
MACRO_END

        LEDGER_CHECK_BALANCE(phys_footprint);
        LEDGER_CHECK_BALANCE(internal);
        LEDGER_CHECK_BALANCE(internal_compressed);
        LEDGER_CHECK_BALANCE(iokit_mapped);
        LEDGER_CHECK_BALANCE(alternate_accounting);
        LEDGER_CHECK_BALANCE(alternate_accounting_compressed);
        LEDGER_CHECK_BALANCE(page_table);
        LEDGER_CHECK_BALANCE(purgeable_volatile);
        LEDGER_CHECK_BALANCE(purgeable_nonvolatile);
        LEDGER_CHECK_BALANCE(purgeable_volatile_compressed);
        LEDGER_CHECK_BALANCE(purgeable_nonvolatile_compressed);
        LEDGER_CHECK_BALANCE(tagged_nofootprint);
        LEDGER_CHECK_BALANCE(tagged_footprint);
        LEDGER_CHECK_BALANCE(tagged_nofootprint_compressed);
        LEDGER_CHECK_BALANCE(tagged_footprint_compressed);
        LEDGER_CHECK_BALANCE(network_volatile);
        LEDGER_CHECK_BALANCE(network_nonvolatile);
        LEDGER_CHECK_BALANCE(network_volatile_compressed);
        LEDGER_CHECK_BALANCE(network_nonvolatile_compressed);
        LEDGER_CHECK_BALANCE(media_nofootprint);
        LEDGER_CHECK_BALANCE(media_footprint);
        LEDGER_CHECK_BALANCE(media_nofootprint_compressed);
        LEDGER_CHECK_BALANCE(media_footprint_compressed);
        LEDGER_CHECK_BALANCE(graphics_nofootprint);
        LEDGER_CHECK_BALANCE(graphics_footprint);
        LEDGER_CHECK_BALANCE(graphics_nofootprint_compressed);
        LEDGER_CHECK_BALANCE(graphics_footprint_compressed);
        LEDGER_CHECK_BALANCE(neural_nofootprint);
        LEDGER_CHECK_BALANCE(neural_footprint);
        LEDGER_CHECK_BALANCE(neural_nofootprint_compressed);
        LEDGER_CHECK_BALANCE(neural_footprint_compressed);

        if (do_panic) {
                if (pmap_ledgers_panic) {
                        panic("pmap_destroy(%p) %d[%s] has imbalanced ledgers\n",
                            pmap, pid, procname);
                } else {
                        printf("pmap_destroy(%p) %d[%s] has imbalanced ledgers\n",
                            pmap, pid, procname);
                }
        }
}
#endif /* MACH_ASSERT */