[apple/xnu.git] / osfmk / kern / kalloc.c

/*
 * Copyright (c) 2000-2011 Apple Computer, 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,
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 * 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:   kern/kalloc.c
 *      Author: Avadis Tevanian, Jr.
 *      Date:   1985
 *
 *      General kernel memory allocator.  This allocator is designed
 *      to be used by the kernel to manage dynamic memory fast.
 */

#include <zone_debug.h>

#include <mach/boolean.h>
#include <mach/sdt.h>
#include <mach/machine/vm_types.h>
#include <mach/vm_param.h>
#include <kern/misc_protos.h>
#include <kern/zalloc.h>
#include <kern/kalloc.h>
#include <kern/ledger.h>
#include <vm/vm_kern.h>
#include <vm/vm_object.h>
#include <vm/vm_map.h>
#include <libkern/OSMalloc.h>
#include <sys/kdebug.h>

#include <san/kasan.h>

#ifdef MACH_BSD
zone_t kalloc_zone(vm_size_t);
#endif

#define KALLOC_MAP_SIZE_MIN  (16 * 1024 * 1024)
#define KALLOC_MAP_SIZE_MAX  (128 * 1024 * 1024)
vm_map_t kalloc_map;
vm_size_t kalloc_max;
vm_size_t kalloc_max_prerounded;
vm_size_t kalloc_kernmap_size;  /* size of kallocs that can come from kernel map */

/* how many times we couldn't allocate out of kalloc_map and fell back to kernel_map */
unsigned long kalloc_fallback_count;

unsigned int kalloc_large_inuse;
vm_size_t    kalloc_large_total;
vm_size_t    kalloc_large_max;
vm_size_t    kalloc_largest_allocated = 0;
uint64_t    kalloc_large_sum;

int     kalloc_fake_zone_index = -1; /* index of our fake zone in statistics arrays */

vm_offset_t     kalloc_map_min;
vm_offset_t     kalloc_map_max;

#ifdef  MUTEX_ZONE
/*
 * Diagnostic code to track mutexes separately rather than via the 2^ zones
 */
zone_t          lck_mtx_zone;
#endif

static void
KALLOC_ZINFO_SALLOC(vm_size_t bytes)
{
        thread_t thr = current_thread();
        ledger_debit(thr->t_ledger, task_ledgers.tkm_shared, bytes);
}

static void
KALLOC_ZINFO_SFREE(vm_size_t bytes)
{
        thread_t thr = current_thread();
        ledger_credit(thr->t_ledger, task_ledgers.tkm_shared, bytes);
}

/*
 * All allocations of size less than kalloc_max are rounded to the next nearest
 * sized zone.  This allocator is built on top of the zone allocator.  A zone
 * is created for each potential size that we are willing to get in small
 * blocks.
 *
 * We assume that kalloc_max is not greater than 64K;
 *
 * Note that kalloc_max is somewhat confusingly named.  It represents the first
 * power of two for which no zone exists.  kalloc_max_prerounded is the
 * smallest allocation size, before rounding, for which no zone exists.
 *
 * Also if the allocation size is more than kalloc_kernmap_size then allocate
 * from kernel map rather than kalloc_map.
 */

#define KALLOC_MINALIGN (1 << KALLOC_LOG2_MINALIGN)
#define KiB(x) (1024 * (x))

/*
 * The k_zone_config table defines the configuration of zones on various platforms.
 * The currently defined list of zones and their per-CPU caching behavior are as
 * follows (X:zone not present; N:zone present no cpu-caching; Y:zone present with cpu-caching):
 *
 * Size       macOS(64-bit)       embedded(32-bit)    embedded(64-bit)
 *--------    ----------------    ----------------    ----------------
 *
 * 8          X                    Y                   X
 * 16         Y                    Y                   Y
 * 24         X                    Y                   X
 * 32         Y                    Y                   Y
 * 40         X                    Y                   X
 * 48         Y                    Y                   Y
 * 64         Y                    Y                   Y
 * 72         X                    Y                   X
 * 80         Y                    X                   Y
 * 88         X                    Y                   X
 * 96         Y                    X                   Y
 * 112        X                    Y                   X
 * 128        Y                    Y                   Y
 * 160        Y                    X                   Y
 * 192        Y                    Y                   Y
 * 224        Y                    X                   Y
 * 256        Y                    Y                   Y
 * 288        Y                    Y                   Y
 * 368        Y                    X                   Y
 * 384        X                    Y                   X
 * 400        Y                    X                   Y
 * 440        X                    Y                   X
 * 512        Y                    Y                   Y
 * 576        Y                    N                   N
 * 768        Y                    N                   N
 * 1024       Y                    Y                   Y
 * 1152       N                    N                   N
 * 1280       N                    N                   N
 * 1536       X                    N                   X
 * 1664       N                    X                   N
 * 2048       Y                    N                   N
 * 2128       X                    N                   X
 * 3072       X                    N                   X
 * 4096       Y                    N                   N
 * 6144       N                    N                   N
 * 8192       Y                    N                   N
 * 16384      N                    N                   N
 * 32768      N                    N                   N
 *
 */
static const struct kalloc_zone_config {
        bool kzc_caching;
        int kzc_size;
        const char *kzc_name;
} k_zone_config[] = {
#define KZC_ENTRY(SIZE, caching) { .kzc_caching = (caching), .kzc_size = (SIZE), .kzc_name = "kalloc." #SIZE }

#if CONFIG_EMBEDDED

#if KALLOC_MINSIZE == 16 && KALLOC_LOG2_MINALIGN == 4
        /* Zone config for embedded 64-bit platforms */
        KZC_ENTRY(16, true),
        KZC_ENTRY(32, true),
        KZC_ENTRY(48, true),
        KZC_ENTRY(64, true),
        KZC_ENTRY(80, true),
        KZC_ENTRY(96, true),
        KZC_ENTRY(128, true),
        KZC_ENTRY(160, true),
        KZC_ENTRY(192, true),
        KZC_ENTRY(224, true),
        KZC_ENTRY(256, true),
        KZC_ENTRY(288, true),
        KZC_ENTRY(368, true),
        KZC_ENTRY(400, true),
        KZC_ENTRY(512, true),
        KZC_ENTRY(576, false),
        KZC_ENTRY(768, false),
        KZC_ENTRY(1024, true),
        KZC_ENTRY(1152, false),
        KZC_ENTRY(1280, false),
        KZC_ENTRY(1664, false),
        KZC_ENTRY(2048, false),
        KZC_ENTRY(4096, false),
        KZC_ENTRY(6144, false),
        KZC_ENTRY(8192, false),
        KZC_ENTRY(16384, false),
        KZC_ENTRY(32768, false),

#elif KALLOC_MINSIZE == 8 && KALLOC_LOG2_MINALIGN == 3
        /* Zone config for embedded 32-bit platforms */
        KZC_ENTRY(8, true),
        KZC_ENTRY(16, true),
        KZC_ENTRY(24, true),
        KZC_ENTRY(32, true),
        KZC_ENTRY(40, true),
        KZC_ENTRY(48, true),
        KZC_ENTRY(64, true),
        KZC_ENTRY(72, true),
        KZC_ENTRY(88, true),
        KZC_ENTRY(112, true),
        KZC_ENTRY(128, true),
        KZC_ENTRY(192, true),
        KZC_ENTRY(256, true),
        KZC_ENTRY(288, true),
        KZC_ENTRY(384, true),
        KZC_ENTRY(440, true),
        KZC_ENTRY(512, true),
        KZC_ENTRY(576, false),
        KZC_ENTRY(768, false),
        KZC_ENTRY(1024, true),
        KZC_ENTRY(1152, false),
        KZC_ENTRY(1280, false),
        KZC_ENTRY(1536, false),
        KZC_ENTRY(2048, false),
        KZC_ENTRY(2128, false),
        KZC_ENTRY(3072, false),
        KZC_ENTRY(4096, false),
        KZC_ENTRY(6144, false),
        KZC_ENTRY(8192, false),
        KZC_ENTRY(16384, false),
        KZC_ENTRY(32768, false),

#else
#error missing or invalid zone size parameters for kalloc
#endif

#else /* CONFIG_EMBEDDED */

        /* Zone config for macOS 64-bit platforms */
        KZC_ENTRY(16, true),
        KZC_ENTRY(32, true),
        KZC_ENTRY(48, true),
        KZC_ENTRY(64, true),
        KZC_ENTRY(80, true),
        KZC_ENTRY(96, true),
        KZC_ENTRY(128, true),
        KZC_ENTRY(160, true),
        KZC_ENTRY(192, true),
        KZC_ENTRY(224, true),
        KZC_ENTRY(256, true),
        KZC_ENTRY(288, true),
        KZC_ENTRY(368, true),
        KZC_ENTRY(400, true),
        KZC_ENTRY(512, true),
        KZC_ENTRY(576, true),
        KZC_ENTRY(768, true),
        KZC_ENTRY(1024, true),
        KZC_ENTRY(1152, false),
        KZC_ENTRY(1280, false),
        KZC_ENTRY(1664, false),
        KZC_ENTRY(2048, true),
        KZC_ENTRY(4096, true),
        KZC_ENTRY(6144, false),
        KZC_ENTRY(8192, true),
        KZC_ENTRY(16384, false),
        KZC_ENTRY(32768, false),

#endif /* CONFIG_EMBEDDED */

#undef KZC_ENTRY
};

#define MAX_K_ZONE (int)(sizeof(k_zone_config) / sizeof(k_zone_config[0]))

/*
 * Many kalloc() allocations are for small structures containing a few
 * pointers and longs - the k_zone_dlut[] direct lookup table, indexed by
 * size normalized to the minimum alignment, finds the right zone index
 * for them in one dereference.
 */

#define INDEX_ZDLUT(size)       \
                        (((size) + KALLOC_MINALIGN - 1) / KALLOC_MINALIGN)
#define N_K_ZDLUT       (2048 / KALLOC_MINALIGN)
/* covers sizes [0 .. 2048 - KALLOC_MINALIGN] */
#define MAX_SIZE_ZDLUT  ((N_K_ZDLUT - 1) * KALLOC_MINALIGN)

static int8_t k_zone_dlut[N_K_ZDLUT];   /* table of indices into k_zone[] */

/*
 * If there's no hit in the DLUT, then start searching from k_zindex_start.
 */
static int k_zindex_start;

static zone_t k_zone[MAX_K_ZONE];

/* #define KALLOC_DEBUG         1 */

/* forward declarations */

lck_grp_t kalloc_lck_grp;
lck_mtx_t kalloc_lock;

#define kalloc_spin_lock()      lck_mtx_lock_spin(&kalloc_lock)
#define kalloc_unlock()         lck_mtx_unlock(&kalloc_lock)


/* OSMalloc local data declarations */
static
queue_head_t    OSMalloc_tag_list;

lck_grp_t *OSMalloc_tag_lck_grp;
lck_mtx_t OSMalloc_tag_lock;

#define OSMalloc_tag_spin_lock()        lck_mtx_lock_spin(&OSMalloc_tag_lock)
#define OSMalloc_tag_unlock()           lck_mtx_unlock(&OSMalloc_tag_lock)


/* OSMalloc forward declarations */
void OSMalloc_init(void);
void OSMalloc_Tagref(OSMallocTag        tag);
void OSMalloc_Tagrele(OSMallocTag       tag);

/*
 *      Initialize the memory allocator.  This should be called only
 *      once on a system wide basis (i.e. first processor to get here
 *      does the initialization).
 *
 *      This initializes all of the zones.
 */

void
kalloc_init(
        void)
{
        kern_return_t retval;
        vm_offset_t min;
        vm_size_t size, kalloc_map_size;
        vm_map_kernel_flags_t vmk_flags;

        /*
         * Scale the kalloc_map_size to physical memory size: stay below
         * 1/8th the total zone map size, or 128 MB (for a 32-bit kernel).
         */
        kalloc_map_size = (vm_size_t)(sane_size >> 5);
#if !__LP64__
        if (kalloc_map_size > KALLOC_MAP_SIZE_MAX) {
                kalloc_map_size = KALLOC_MAP_SIZE_MAX;
        }
#endif /* !__LP64__ */
        if (kalloc_map_size < KALLOC_MAP_SIZE_MIN) {
                kalloc_map_size = KALLOC_MAP_SIZE_MIN;
        }

        vmk_flags = VM_MAP_KERNEL_FLAGS_NONE;
        vmk_flags.vmkf_permanent = TRUE;

        retval = kmem_suballoc(kernel_map, &min, kalloc_map_size,
            FALSE,
            (VM_FLAGS_ANYWHERE),
            vmk_flags,
            VM_KERN_MEMORY_KALLOC,
            &kalloc_map);

        if (retval != KERN_SUCCESS) {
                panic("kalloc_init: kmem_suballoc failed");
        }

        kalloc_map_min = min;
        kalloc_map_max = min + kalloc_map_size - 1;

        /*
         * Create zones up to a least 4 pages because small page-multiples are
         * common allocations.  Also ensure that zones up to size 16KB bytes exist.
         * This is desirable because messages are allocated with kalloc(), and
         * messages up through size 8192 are common.
         */
        kalloc_max = PAGE_SIZE << 2;
        if (kalloc_max < KiB(16)) {
                kalloc_max = KiB(16);
        }
        assert(kalloc_max <= KiB(64)); /* assumption made in size arrays */

        kalloc_max_prerounded = kalloc_max / 2 + 1;
        /* allocations larger than 16 times kalloc_max go directly to kernel map */
        kalloc_kernmap_size = (kalloc_max * 16) + 1;
        kalloc_largest_allocated = kalloc_kernmap_size;

        /*
         * Allocate a zone for each size we are going to handle.
         */
        for (int i = 0; i < MAX_K_ZONE && (size = k_zone_config[i].kzc_size) < kalloc_max; i++) {
                k_zone[i] = zinit(size, size, size, k_zone_config[i].kzc_name);

                /*
                 * Don't charge the caller for the allocation, as we aren't sure how
                 * the memory will be handled.
                 */
                zone_change(k_zone[i], Z_CALLERACCT, FALSE);
#if VM_MAX_TAG_ZONES
                if (zone_tagging_on) {
                        zone_change(k_zone[i], Z_TAGS_ENABLED, TRUE);
                }
#endif
                zone_change(k_zone[i], Z_KASAN_QUARANTINE, FALSE);
                if (k_zone_config[i].kzc_caching) {
                        zone_change(k_zone[i], Z_CACHING_ENABLED, TRUE);
                }
        }

        /*
         * Build the Direct LookUp Table for small allocations
         */
        size = 0;
        for (int i = 0; i <= N_K_ZDLUT; i++, size += KALLOC_MINALIGN) {
                int zindex = 0;

                while ((vm_size_t)k_zone_config[zindex].kzc_size < size) {
                        zindex++;
                }

                if (i == N_K_ZDLUT) {
                        k_zindex_start = zindex;
                        break;
                }
                k_zone_dlut[i] = (int8_t)zindex;
        }

#ifdef KALLOC_DEBUG
        printf("kalloc_init: k_zindex_start %d\n", k_zindex_start);

        /*
         * Do a quick synthesis to see how well/badly we can
         * find-a-zone for a given size.
         * Useful when debugging/tweaking the array of zone sizes.
         * Cache misses probably more critical than compare-branches!
         */
        for (int i = 0; i < MAX_K_ZONE; i++) {
                vm_size_t testsize = (vm_size_t)k_zone_config[i].kzc_size - 1;
                int compare = 0;
                int zindex;

                if (testsize < MAX_SIZE_ZDLUT) {
                        compare += 1;   /* 'if' (T) */

                        long dindex = INDEX_ZDLUT(testsize);
                        zindex = (int)k_zone_dlut[dindex];
                } else if (testsize < kalloc_max_prerounded) {
                        compare += 2;   /* 'if' (F), 'if' (T) */

                        zindex = k_zindex_start;
                        while ((vm_size_t)k_zone_config[zindex].kzc_size < testsize) {
                                zindex++;
                                compare++;      /* 'while' (T) */
                        }
                        compare++;      /* 'while' (F) */
                } else {
                        break;  /* not zone-backed */
                }
                zone_t z = k_zone[zindex];
                printf("kalloc_init: req size %4lu: %11s took %d compare%s\n",
                    (unsigned long)testsize, z->zone_name, compare,
                    compare == 1 ? "" : "s");
        }
#endif

        lck_grp_init(&kalloc_lck_grp, "kalloc.large", LCK_GRP_ATTR_NULL);
        lck_mtx_init(&kalloc_lock, &kalloc_lck_grp, LCK_ATTR_NULL);
        OSMalloc_init();
#ifdef  MUTEX_ZONE
        lck_mtx_zone = zinit(sizeof(struct _lck_mtx_), 1024 * 256, 4096, "lck_mtx");
#endif
}

/*
 * Given an allocation size, return the kalloc zone it belongs to.
 * Direct LookUp Table variant.
 */
static __inline zone_t
get_zone_dlut(vm_size_t size)
{
        long dindex = INDEX_ZDLUT(size);
        int zindex = (int)k_zone_dlut[dindex];
        return k_zone[zindex];
}

/* As above, but linear search k_zone_config[] for the next zone that fits. */

static __inline zone_t
get_zone_search(vm_size_t size, int zindex)
{
        assert(size < kalloc_max_prerounded);

        while ((vm_size_t)k_zone_config[zindex].kzc_size < size) {
                zindex++;
        }

        assert(zindex < MAX_K_ZONE &&
            (vm_size_t)k_zone_config[zindex].kzc_size < kalloc_max);

        return k_zone[zindex];
}

static vm_size_t
vm_map_lookup_kalloc_entry_locked(
        vm_map_t        map,
        void            *addr)
{
        boolean_t       ret;
        vm_map_entry_t  vm_entry = NULL;

        ret = vm_map_lookup_entry(map, (vm_map_offset_t)addr, &vm_entry);
        if (!ret) {
                panic("Attempting to lookup/free an address not allocated via kalloc! (vm_map_lookup_entry() failed map: %p, addr: %p)\n",
                    map, addr);
        }
        if (vm_entry->vme_start != (vm_map_offset_t)addr) {
                panic("Attempting to lookup/free the middle of a kalloc'ed element! (map: %p, addr: %p, entry: %p)\n",
                    map, addr, vm_entry);
        }
        if (!vm_entry->vme_atomic) {
                panic("Attempting to lookup/free an address not managed by kalloc! (map: %p, addr: %p, entry: %p)\n",
                    map, addr, vm_entry);
        }
        return vm_entry->vme_end - vm_entry->vme_start;
}

#if KASAN_KALLOC
/*
 * KASAN kalloc stashes the original user-requested size away in the poisoned
 * area. Return that directly.
 */
vm_size_t
kalloc_size(void *addr)
{
        (void)vm_map_lookup_kalloc_entry_locked; /* silence warning */
        return kasan_user_size((vm_offset_t)addr);
}
#else
vm_size_t
kalloc_size(
        void            *addr)
{
        vm_map_t                map;
        vm_size_t               size;

        size = zone_element_size(addr, NULL);
        if (size) {
                return size;
        }
        if (((vm_offset_t)addr >= kalloc_map_min) && ((vm_offset_t)addr < kalloc_map_max)) {
                map = kalloc_map;
        } else {
                map = kernel_map;
        }
        vm_map_lock_read(map);
        size = vm_map_lookup_kalloc_entry_locked(map, addr);
        vm_map_unlock_read(map);
        return size;
}
#endif

vm_size_t
kalloc_bucket_size(
        vm_size_t       size)
{
        zone_t          z;
        vm_map_t        map;

        if (size < MAX_SIZE_ZDLUT) {
                z = get_zone_dlut(size);
                return z->elem_size;
        }

        if (size < kalloc_max_prerounded) {
                z = get_zone_search(size, k_zindex_start);
                return z->elem_size;
        }

        if (size >= kalloc_kernmap_size) {
                map = kernel_map;
        } else {
                map = kalloc_map;
        }

        return vm_map_round_page(size, VM_MAP_PAGE_MASK(map));
}

#if KASAN_KALLOC
vm_size_t
(kfree_addr)(void *addr)
{
        vm_size_t origsz = kalloc_size(addr);
        kfree(addr, origsz);
        return origsz;
}
#else
vm_size_t
(kfree_addr)(
        void            *addr)
{
        vm_map_t        map;
        vm_size_t       size = 0;
        kern_return_t   ret;
        zone_t                  z;

        size = zone_element_size(addr, &z);
        if (size) {
                DTRACE_VM3(kfree, vm_size_t, -1, vm_size_t, z->elem_size, void*, addr);
                zfree(z, addr);
                return size;
        }

        if (((vm_offset_t)addr >= kalloc_map_min) && ((vm_offset_t)addr < kalloc_map_max)) {
                map = kalloc_map;
        } else {
                map = kernel_map;
        }
        if ((vm_offset_t)addr < VM_MIN_KERNEL_AND_KEXT_ADDRESS) {
                panic("kfree on an address not in the kernel & kext address range! addr: %p\n", addr);
        }

        vm_map_lock(map);
        size = vm_map_lookup_kalloc_entry_locked(map, addr);
        ret = vm_map_remove_locked(map,
            vm_map_trunc_page((vm_map_offset_t)addr,
            VM_MAP_PAGE_MASK(map)),
            vm_map_round_page((vm_map_offset_t)addr + size,
            VM_MAP_PAGE_MASK(map)),
            VM_MAP_REMOVE_KUNWIRE);
        if (ret != KERN_SUCCESS) {
                panic("vm_map_remove_locked() failed for kalloc vm_entry! addr: %p, map: %p ret: %d\n",
                    addr, map, ret);
        }
        vm_map_unlock(map);
        DTRACE_VM3(kfree, vm_size_t, -1, vm_size_t, size, void*, addr);

        kalloc_spin_lock();
        kalloc_large_total -= size;
        kalloc_large_inuse--;
        kalloc_unlock();

        KALLOC_ZINFO_SFREE(size);
        return size;
}
#endif

void *
kalloc_canblock(
        vm_size_t              * psize,
        boolean_t              canblock,
        vm_allocation_site_t * site)
{
        zone_t z;
        vm_size_t size;
        void *addr;
        vm_tag_t tag;

        tag = VM_KERN_MEMORY_KALLOC;
        size = *psize;

#if KASAN_KALLOC
        /* expand the allocation to accomodate redzones */
        vm_size_t req_size = size;
        size = kasan_alloc_resize(req_size);
#endif

        if (size < MAX_SIZE_ZDLUT) {
                z = get_zone_dlut(size);
        } else if (size < kalloc_max_prerounded) {
                z = get_zone_search(size, k_zindex_start);
        } else {
                /*
                 * If size is too large for a zone, then use kmem_alloc.
                 * (We use kmem_alloc instead of kmem_alloc_kobject so that
                 * krealloc can use kmem_realloc.)
                 */
                vm_map_t alloc_map;

                /* kmem_alloc could block so we return if noblock */
                if (!canblock) {
                        return NULL;
                }

#if KASAN_KALLOC
                /* large allocation - use guard pages instead of small redzones */
                size = round_page(req_size + 2 * PAGE_SIZE);
                assert(size >= MAX_SIZE_ZDLUT && size >= kalloc_max_prerounded);
#endif

                if (size >= kalloc_kernmap_size) {
                        alloc_map = kernel_map;
                } else {
                        alloc_map = kalloc_map;
                }

                if (site) {
                        tag = vm_tag_alloc(site);
                }

                if (kmem_alloc_flags(alloc_map, (vm_offset_t *)&addr, size, tag, KMA_ATOMIC) != KERN_SUCCESS) {
                        if (alloc_map != kernel_map) {
                                if (kalloc_fallback_count++ == 0) {
                                        printf("%s: falling back to kernel_map\n", __func__);
                                }
                                if (kmem_alloc_flags(kernel_map, (vm_offset_t *)&addr, size, tag, KMA_ATOMIC) != KERN_SUCCESS) {
                                        addr = NULL;
                                }
                        } else {
                                addr = NULL;
                        }
                }

                if (addr != NULL) {
                        kalloc_spin_lock();
                        /*
                         * Thread-safe version of the workaround for 4740071
                         * (a double FREE())
                         */
                        if (size > kalloc_largest_allocated) {
                                kalloc_largest_allocated = size;
                        }

                        kalloc_large_inuse++;
                        kalloc_large_total += size;
                        kalloc_large_sum += size;

                        if (kalloc_large_total > kalloc_large_max) {
                                kalloc_large_max = kalloc_large_total;
                        }

                        kalloc_unlock();

                        KALLOC_ZINFO_SALLOC(size);
                }
#if KASAN_KALLOC
                /* fixup the return address to skip the redzone */
                addr = (void *)kasan_alloc((vm_offset_t)addr, size, req_size, PAGE_SIZE);
#else
                *psize = round_page(size);
#endif
                DTRACE_VM3(kalloc, vm_size_t, size, vm_size_t, *psize, void*, addr);
                return addr;
        }
#ifdef KALLOC_DEBUG
        if (size > z->elem_size) {
                panic("%s: z %p (%s) but requested size %lu", __func__,
                    z, z->zone_name, (unsigned long)size);
        }
#endif

        assert(size <= z->elem_size);

#if VM_MAX_TAG_ZONES
        if (z->tags && site) {
                tag = vm_tag_alloc(site);
                if (!canblock && !vm_allocation_zone_totals[tag]) {
                        tag = VM_KERN_MEMORY_KALLOC;
                }
        }
#endif

        addr =  zalloc_canblock_tag(z, canblock, size, tag);

#if KASAN_KALLOC
        /* fixup the return address to skip the redzone */
        addr = (void *)kasan_alloc((vm_offset_t)addr, z->elem_size, req_size, KASAN_GUARD_SIZE);

        /* For KASan, the redzone lives in any additional space, so don't
         * expand the allocation. */
#else
        *psize = z->elem_size;
#endif

        DTRACE_VM3(kalloc, vm_size_t, size, vm_size_t, *psize, void*, addr);
        return addr;
}

void *
kalloc_external(
        vm_size_t size);
void *
kalloc_external(
        vm_size_t size)
{
        return kalloc_tag_bt(size, VM_KERN_MEMORY_KALLOC);
}

void
(kfree)(
        void            *data,
        vm_size_t       size)
{
        zone_t z;

#if KASAN_KALLOC
        /*
         * Resize back to the real allocation size and hand off to the KASan
         * quarantine. `data` may then point to a different allocation.
         */
        vm_size_t user_size = size;
        kasan_check_free((vm_address_t)data, size, KASAN_HEAP_KALLOC);
        data = (void *)kasan_dealloc((vm_address_t)data, &size);
        kasan_free(&data, &size, KASAN_HEAP_KALLOC, NULL, user_size, true);
        if (!data) {
                return;
        }
#endif

        if (size < MAX_SIZE_ZDLUT) {
                z = get_zone_dlut(size);
        } else if (size < kalloc_max_prerounded) {
                z = get_zone_search(size, k_zindex_start);
        } else {
                /* if size was too large for a zone, then use kmem_free */

                vm_map_t alloc_map = kernel_map;

                if ((((vm_offset_t) data) >= kalloc_map_min) && (((vm_offset_t) data) <= kalloc_map_max)) {
                        alloc_map = kalloc_map;
                }
                if (size > kalloc_largest_allocated) {
                        panic("kfree: size %lu > kalloc_largest_allocated %lu", (unsigned long)size, (unsigned long)kalloc_largest_allocated);
                }
                kmem_free(alloc_map, (vm_offset_t)data, size);
                kalloc_spin_lock();

                kalloc_large_total -= size;
                kalloc_large_inuse--;

                kalloc_unlock();

#if !KASAN_KALLOC
                DTRACE_VM3(kfree, vm_size_t, size, vm_size_t, size, void*, data);
#endif

                KALLOC_ZINFO_SFREE(size);
                return;
        }

        /* free to the appropriate zone */
#ifdef KALLOC_DEBUG
        if (size > z->elem_size) {
                panic("%s: z %p (%s) but requested size %lu", __func__,
                    z, z->zone_name, (unsigned long)size);
        }
#endif
        assert(size <= z->elem_size);
#if !KASAN_KALLOC
        DTRACE_VM3(kfree, vm_size_t, size, vm_size_t, z->elem_size, void*, data);
#endif
        zfree(z, data);
}

#ifdef MACH_BSD
zone_t
kalloc_zone(
        vm_size_t       size)
{
        if (size < MAX_SIZE_ZDLUT) {
                return get_zone_dlut(size);
        }
        if (size <= kalloc_max) {
                return get_zone_search(size, k_zindex_start);
        }
        return ZONE_NULL;
}
#endif

void
OSMalloc_init(
        void)
{
        queue_init(&OSMalloc_tag_list);

        OSMalloc_tag_lck_grp = lck_grp_alloc_init("OSMalloc_tag", LCK_GRP_ATTR_NULL);
        lck_mtx_init(&OSMalloc_tag_lock, OSMalloc_tag_lck_grp, LCK_ATTR_NULL);
}

OSMallocTag
OSMalloc_Tagalloc(
        const char                      *str,
        uint32_t                        flags)
{
        OSMallocTag       OSMTag;

        OSMTag = (OSMallocTag)kalloc(sizeof(*OSMTag));

        bzero((void *)OSMTag, sizeof(*OSMTag));

        if (flags & OSMT_PAGEABLE) {
                OSMTag->OSMT_attr = OSMT_ATTR_PAGEABLE;
        }

        OSMTag->OSMT_refcnt = 1;

        strlcpy(OSMTag->OSMT_name, str, OSMT_MAX_NAME);

        OSMalloc_tag_spin_lock();
        enqueue_tail(&OSMalloc_tag_list, (queue_entry_t)OSMTag);
        OSMalloc_tag_unlock();
        OSMTag->OSMT_state = OSMT_VALID;
        return OSMTag;
}

void
OSMalloc_Tagref(
        OSMallocTag            tag)
{
        if (!((tag->OSMT_state & OSMT_VALID_MASK) == OSMT_VALID)) {
                panic("OSMalloc_Tagref():'%s' has bad state 0x%08X\n", tag->OSMT_name, tag->OSMT_state);
        }

        (void)hw_atomic_add(&tag->OSMT_refcnt, 1);
}

void
OSMalloc_Tagrele(
        OSMallocTag            tag)
{
        if (!((tag->OSMT_state & OSMT_VALID_MASK) == OSMT_VALID)) {
                panic("OSMalloc_Tagref():'%s' has bad state 0x%08X\n", tag->OSMT_name, tag->OSMT_state);
        }

        if (hw_atomic_sub(&tag->OSMT_refcnt, 1) == 0) {
                if (hw_compare_and_store(OSMT_VALID | OSMT_RELEASED, OSMT_VALID | OSMT_RELEASED, &tag->OSMT_state)) {
                        OSMalloc_tag_spin_lock();
                        (void)remque((queue_entry_t)tag);
                        OSMalloc_tag_unlock();
                        kfree(tag, sizeof(*tag));
                } else {
                        panic("OSMalloc_Tagrele():'%s' has refcnt 0\n", tag->OSMT_name);
                }
        }
}

void
OSMalloc_Tagfree(
        OSMallocTag            tag)
{
        if (!hw_compare_and_store(OSMT_VALID, OSMT_VALID | OSMT_RELEASED, &tag->OSMT_state)) {
                panic("OSMalloc_Tagfree():'%s' has bad state 0x%08X \n", tag->OSMT_name, tag->OSMT_state);
        }

        if (hw_atomic_sub(&tag->OSMT_refcnt, 1) == 0) {
                OSMalloc_tag_spin_lock();
                (void)remque((queue_entry_t)tag);
                OSMalloc_tag_unlock();
                kfree(tag, sizeof(*tag));
        }
}

void *
OSMalloc(
        uint32_t                        size,
        OSMallocTag                     tag)
{
        void                    *addr = NULL;
        kern_return_t   kr;

        OSMalloc_Tagref(tag);
        if ((tag->OSMT_attr & OSMT_PAGEABLE)
            && (size & ~PAGE_MASK)) {
                if ((kr = kmem_alloc_pageable_external(kernel_map, (vm_offset_t *)&addr, size)) != KERN_SUCCESS) {
                        addr = NULL;
                }
        } else {
                addr = kalloc_tag_bt((vm_size_t)size, VM_KERN_MEMORY_KALLOC);
        }

        if (!addr) {
                OSMalloc_Tagrele(tag);
        }

        return addr;
}

void *
OSMalloc_nowait(
        uint32_t                        size,
        OSMallocTag                     tag)
{
        void    *addr = NULL;

        if (tag->OSMT_attr & OSMT_PAGEABLE) {
                return NULL;
        }

        OSMalloc_Tagref(tag);
        /* XXX: use non-blocking kalloc for now */
        addr = kalloc_noblock_tag_bt((vm_size_t)size, VM_KERN_MEMORY_KALLOC);
        if (addr == NULL) {
                OSMalloc_Tagrele(tag);
        }

        return addr;
}

void *
OSMalloc_noblock(
        uint32_t                        size,
        OSMallocTag                     tag)
{
        void    *addr = NULL;

        if (tag->OSMT_attr & OSMT_PAGEABLE) {
                return NULL;
        }

        OSMalloc_Tagref(tag);
        addr = kalloc_noblock_tag_bt((vm_size_t)size, VM_KERN_MEMORY_KALLOC);
        if (addr == NULL) {
                OSMalloc_Tagrele(tag);
        }

        return addr;
}

void
OSFree(
        void                            *addr,
        uint32_t                        size,
        OSMallocTag                     tag)
{
        if ((tag->OSMT_attr & OSMT_PAGEABLE)
            && (size & ~PAGE_MASK)) {
                kmem_free(kernel_map, (vm_offset_t)addr, size);
        } else {
                kfree(addr, size);
        }

        OSMalloc_Tagrele(tag);
}

uint32_t
OSMalloc_size(
        void                            *addr)
{
        return (uint32_t)kalloc_size(addr);
}