xnu-517.12.7.tar.gz

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

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This 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 OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_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_kern.c
 *      Author: Avadis Tevanian, Jr., Michael Wayne Young
 *      Date:   1985
 *
 *      Kernel memory management.
 */

#include <cpus.h>
#include <mach/kern_return.h>
#include <mach/vm_param.h>
#include <kern/assert.h>
#include <kern/lock.h>
#include <kern/thread.h>
#include <vm/vm_kern.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <kern/misc_protos.h>
#include <vm/cpm.h>

#include <string.h>
/*
 *      Variables exported by this module.
 */

vm_map_t        kernel_map;
vm_map_t        kernel_pageable_map;

/*
 * Forward declarations for internal functions.
 */
extern kern_return_t kmem_alloc_pages(
        register vm_object_t            object,
        register vm_object_offset_t     offset,
        register vm_size_t              size);

extern void kmem_remap_pages(
        register vm_object_t            object,
        register vm_object_offset_t     offset,
        register vm_offset_t            start,
        register vm_offset_t            end,
        vm_prot_t                       protection);

kern_return_t
kmem_alloc_contig(
        vm_map_t        map,
        vm_offset_t     *addrp,
        vm_size_t       size,
        vm_offset_t     mask,
        int             flags)
{
        vm_object_t             object;
        vm_page_t               m, pages;
        kern_return_t           kr;
        vm_offset_t             addr, i; 
        vm_object_offset_t      offset;
        vm_map_entry_t          entry;

        if (map == VM_MAP_NULL || (flags && (flags ^ KMA_KOBJECT))) 
                return KERN_INVALID_ARGUMENT;
        
        if (size == 0) {
                *addrp = 0;
                return KERN_INVALID_ARGUMENT;
        }

        size = round_page_32(size);
        if ((flags & KMA_KOBJECT) == 0) {
                object = vm_object_allocate(size);
                kr = vm_map_find_space(map, &addr, size, mask, &entry);
        }
        else {
                object = kernel_object;
                kr = vm_map_find_space(map, &addr, size, mask, &entry);
        }

        if ((flags & KMA_KOBJECT) == 0) {
                entry->object.vm_object = object;
                entry->offset = offset = 0;
        } else {
                offset = addr - VM_MIN_KERNEL_ADDRESS;

                if (entry->object.vm_object == VM_OBJECT_NULL) {
                        vm_object_reference(object);
                        entry->object.vm_object = object;
                        entry->offset = offset;
                }
        }

        if (kr != KERN_SUCCESS) {
                if ((flags & KMA_KOBJECT) == 0)
                        vm_object_deallocate(object);
                return kr;
        }

        vm_map_unlock(map);

        kr = cpm_allocate(size, &pages, FALSE);

        if (kr != KERN_SUCCESS) {
                vm_map_remove(map, addr, addr + size, 0);
                *addrp = 0;
                return kr;
        }

        vm_object_lock(object);
        for (i = 0; i < size; i += PAGE_SIZE) {
                m = pages;
                pages = NEXT_PAGE(m);
                m->busy = FALSE;
                vm_page_insert(m, object, offset + i);
        }
        vm_object_unlock(object);

        if ((kr = vm_map_wire(map, addr, addr + size, VM_PROT_DEFAULT, FALSE)) 
                != KERN_SUCCESS) {
                if (object == kernel_object) {
                        vm_object_lock(object);
                        vm_object_page_remove(object, offset, offset + size);
                        vm_object_unlock(object);
                }
                vm_map_remove(map, addr, addr + size, 0);
                return kr;
        }
        if (object == kernel_object)
                vm_map_simplify(map, addr);

        *addrp = addr;
        return KERN_SUCCESS;
}

/*
 * Master entry point for allocating kernel memory.
 * NOTE: this routine is _never_ interrupt safe.
 *
 * map          : map to allocate into
 * addrp        : pointer to start address of new memory
 * size         : size of memory requested
 * flags        : options
 *                KMA_HERE              *addrp is base address, else "anywhere"
 *                KMA_NOPAGEWAIT        don't wait for pages if unavailable
 *                KMA_KOBJECT           use kernel_object
 */

kern_return_t
kernel_memory_allocate(
        register vm_map_t       map,
        register vm_offset_t    *addrp,
        register vm_size_t      size,
        register vm_offset_t    mask,
        int                     flags)
{
        vm_object_t             object = VM_OBJECT_NULL;
        vm_map_entry_t          entry;
        vm_object_offset_t              offset;
        vm_offset_t             addr;
        vm_offset_t             i;
        kern_return_t           kr;

        size = round_page_32(size);
        if ((flags & KMA_KOBJECT) == 0) {
                /*
                 *      Allocate a new object.  We must do this before locking
                 *      the map, or risk deadlock with the default pager:
                 *              device_read_alloc uses kmem_alloc,
                 *              which tries to allocate an object,
                 *              which uses kmem_alloc_wired to get memory,
                 *              which blocks for pages.
                 *              then the default pager needs to read a block
                 *              to process a memory_object_data_write,
                 *              and device_read_alloc calls kmem_alloc
                 *              and deadlocks on the map lock.
                 */
                object = vm_object_allocate(size);
                kr = vm_map_find_space(map, &addr, size, mask, &entry);
        }
        else {
                object = kernel_object;
                kr = vm_map_find_space(map, &addr, size, mask, &entry);
        }
        if (kr != KERN_SUCCESS) {
                if ((flags & KMA_KOBJECT) == 0)
                        vm_object_deallocate(object);
                return kr;
        }

        if ((flags & KMA_KOBJECT) == 0) {
                entry->object.vm_object = object;
                entry->offset = offset = 0;
        } else {
                offset = addr - VM_MIN_KERNEL_ADDRESS;

                if (entry->object.vm_object == VM_OBJECT_NULL) {
                        vm_object_reference(object);
                        entry->object.vm_object = object;
                        entry->offset = offset;
                }
        }

        /*
         *      Since we have not given out this address yet,
         *      it is safe to unlock the map. Except of course
         *      we must make certain no one coalesces our address
         *      or does a blind vm_deallocate and removes the object
         *      an extra object reference will suffice to protect
         *      against both contingencies.
         */
        vm_object_reference(object);
        vm_map_unlock(map);

        vm_object_lock(object);
        for (i = 0; i < size; i += PAGE_SIZE) {
                vm_page_t       mem;

                while ((mem = vm_page_alloc(object, 
                                        offset + (vm_object_offset_t)i))
                            == VM_PAGE_NULL) {
                        if (flags & KMA_NOPAGEWAIT) {
                                if (object == kernel_object)
                                        vm_object_page_remove(object, offset,
                                                offset + (vm_object_offset_t)i);
                                vm_object_unlock(object);
                                vm_map_remove(map, addr, addr + size, 0);
                                vm_object_deallocate(object);
                                return KERN_RESOURCE_SHORTAGE;
                        }
                        vm_object_unlock(object);
                        VM_PAGE_WAIT();
                        vm_object_lock(object);
                }
                mem->busy = FALSE;
        }
        vm_object_unlock(object);

        if ((kr = vm_map_wire(map, addr, addr + size, VM_PROT_DEFAULT, FALSE)) 
                != KERN_SUCCESS) {
                if (object == kernel_object) {
                        vm_object_lock(object);
                        vm_object_page_remove(object, offset, offset + size);
                        vm_object_unlock(object);
                }
                vm_map_remove(map, addr, addr + size, 0);
                vm_object_deallocate(object);
                return (kr);
        }
        /* now that the page is wired, we no longer have to fear coalesce */
        vm_object_deallocate(object);
        if (object == kernel_object)
                vm_map_simplify(map, addr);

        /*
         *      Return the memory, not zeroed.
         */
#if     (NCPUS > 1)  &&  i860
        bzero( addr, size );
#endif                                  /* #if (NCPUS > 1)  &&  i860 */
        *addrp = addr;
        return KERN_SUCCESS;
}

/*
 *      kmem_alloc:
 *
 *      Allocate wired-down memory in the kernel's address map
 *      or a submap.  The memory is not zero-filled.
 */

kern_return_t
kmem_alloc(
        vm_map_t        map,
        vm_offset_t     *addrp,
        vm_size_t       size)
{
        return kernel_memory_allocate(map, addrp, size, 0, 0);
}

/*
 *      kmem_realloc:
 *
 *      Reallocate wired-down memory in the kernel's address map
 *      or a submap.  Newly allocated pages are not zeroed.
 *      This can only be used on regions allocated with kmem_alloc.
 *
 *      If successful, the pages in the old region are mapped twice.
 *      The old region is unchanged.  Use kmem_free to get rid of it.
 */
kern_return_t
kmem_realloc(
        vm_map_t        map,
        vm_offset_t     oldaddr,
        vm_size_t       oldsize,
        vm_offset_t     *newaddrp,
        vm_size_t       newsize)
{
        vm_offset_t     oldmin, oldmax;
        vm_offset_t     newaddr;
        vm_offset_t     offset;
        vm_object_t     object;
        vm_map_entry_t  oldentry, newentry;
        vm_page_t       mem;
        kern_return_t   kr;

        oldmin = trunc_page_32(oldaddr);
        oldmax = round_page_32(oldaddr + oldsize);
        oldsize = oldmax - oldmin;
        newsize = round_page_32(newsize);


        /*
         *      Find the VM object backing the old region.
         */

        vm_map_lock(map);

        if (!vm_map_lookup_entry(map, oldmin, &oldentry))
                panic("kmem_realloc");
        object = oldentry->object.vm_object;

        /*
         *      Increase the size of the object and
         *      fill in the new region.
         */

        vm_object_reference(object);
        /* by grabbing the object lock before unlocking the map */
        /* we guarantee that we will panic if more than one     */
        /* attempt is made to realloc a kmem_alloc'd area       */
        vm_object_lock(object);
        vm_map_unlock(map);
        if (object->size != oldsize)
                panic("kmem_realloc");
        object->size = newsize;
        vm_object_unlock(object);

        /* allocate the new pages while expanded portion of the */
        /* object is still not mapped */
        kmem_alloc_pages(object, oldsize, newsize-oldsize);


        /*
         *      Find space for the new region.
         */

        kr = vm_map_find_space(map, &newaddr, newsize, (vm_offset_t) 0,
                               &newentry);
        if (kr != KERN_SUCCESS) {
                vm_object_lock(object);
                for(offset = oldsize; 
                                offset<newsize; offset+=PAGE_SIZE) {
                        if ((mem = vm_page_lookup(object, offset)) != VM_PAGE_NULL) {
                                vm_page_lock_queues();
                                vm_page_free(mem);
                                vm_page_unlock_queues();
                        }
                }
                object->size = oldsize;
                vm_object_unlock(object);
                vm_object_deallocate(object);
                return kr;
        }
        newentry->object.vm_object = object;
        newentry->offset = 0;
        assert (newentry->wired_count == 0);

        
        /* add an extra reference in case we have someone doing an */
        /* unexpected deallocate */
        vm_object_reference(object);
        vm_map_unlock(map);

        if ((kr = vm_map_wire(map, newaddr, newaddr + newsize, 
                                VM_PROT_DEFAULT, FALSE)) != KERN_SUCCESS) {
                vm_map_remove(map, newaddr, newaddr + newsize, 0);
                vm_object_lock(object);
                for(offset = oldsize; 
                                offset<newsize; offset+=PAGE_SIZE) {
                        if ((mem = vm_page_lookup(object, offset)) != VM_PAGE_NULL) {
                                vm_page_lock_queues();
                                vm_page_free(mem);
                                vm_page_unlock_queues();
                        }
                }
                object->size = oldsize;
                vm_object_unlock(object);
                vm_object_deallocate(object);
                return (kr);
        }
        vm_object_deallocate(object);


        *newaddrp = newaddr;
        return KERN_SUCCESS;
}

/*
 *      kmem_alloc_wired:
 *
 *      Allocate wired-down memory in the kernel's address map
 *      or a submap.  The memory is not zero-filled.
 *
 *      The memory is allocated in the kernel_object.
 *      It may not be copied with vm_map_copy, and
 *      it may not be reallocated with kmem_realloc.
 */

kern_return_t
kmem_alloc_wired(
        vm_map_t        map,
        vm_offset_t     *addrp,
        vm_size_t       size)
{
        return kernel_memory_allocate(map, addrp, size, 0, KMA_KOBJECT);
}

/*
 *      kmem_alloc_aligned:
 *
 *      Like kmem_alloc_wired, except that the memory is aligned.
 *      The size should be a power-of-2.
 */

kern_return_t
kmem_alloc_aligned(
        vm_map_t        map,
        vm_offset_t     *addrp,
        vm_size_t       size)
{
        if ((size & (size - 1)) != 0)
                panic("kmem_alloc_aligned: size not aligned");
        return kernel_memory_allocate(map, addrp, size, size - 1, KMA_KOBJECT);
}

/*
 *      kmem_alloc_pageable:
 *
 *      Allocate pageable memory in the kernel's address map.
 */

kern_return_t
kmem_alloc_pageable(
        vm_map_t        map,
        vm_offset_t     *addrp,
        vm_size_t       size)
{
        vm_offset_t addr;
        kern_return_t kr;

#ifndef normal
        addr = (vm_map_min(map)) + 0x1000;
#else
        addr = vm_map_min(map);
#endif
        kr = vm_map_enter(map, &addr, round_page_32(size),
                          (vm_offset_t) 0, TRUE,
                          VM_OBJECT_NULL, (vm_object_offset_t) 0, FALSE,
                          VM_PROT_DEFAULT, VM_PROT_ALL, VM_INHERIT_DEFAULT);
        if (kr != KERN_SUCCESS)
                return kr;

        *addrp = addr;
        return KERN_SUCCESS;
}

/*
 *      kmem_free:
 *
 *      Release a region of kernel virtual memory allocated
 *      with kmem_alloc, kmem_alloc_wired, or kmem_alloc_pageable,
 *      and return the physical pages associated with that region.
 */

void
kmem_free(
        vm_map_t        map,
        vm_offset_t     addr,
        vm_size_t       size)
{
        kern_return_t kr;

        kr = vm_map_remove(map, trunc_page_32(addr),
                                round_page_32(addr + size), 
                                VM_MAP_REMOVE_KUNWIRE);
        if (kr != KERN_SUCCESS)
                panic("kmem_free");
}

/*
 *      Allocate new pages in an object.
 */

kern_return_t
kmem_alloc_pages(
        register vm_object_t            object,
        register vm_object_offset_t     offset,
        register vm_size_t              size)
{

        size = round_page_32(size);
        vm_object_lock(object);
        while (size) {
            register vm_page_t  mem;


            /*
             *  Allocate a page
             */
            while ((mem = vm_page_alloc(object, offset))
                         == VM_PAGE_NULL) {
                vm_object_unlock(object);
                VM_PAGE_WAIT();
                vm_object_lock(object);
            }


            offset += PAGE_SIZE;
            size -= PAGE_SIZE;
            mem->busy = FALSE;
        }
        vm_object_unlock(object);
        return KERN_SUCCESS;
}

/*
 *      Remap wired pages in an object into a new region.
 *      The object is assumed to be mapped into the kernel map or
 *      a submap.
 */
void
kmem_remap_pages(
        register vm_object_t            object,
        register vm_object_offset_t     offset,
        register vm_offset_t            start,
        register vm_offset_t            end,
        vm_prot_t                       protection)
{
        /*
         *      Mark the pmap region as not pageable.
         */
        pmap_pageable(kernel_pmap, start, end, FALSE);

        while (start < end) {
            register vm_page_t  mem;

            vm_object_lock(object);

            /*
             *  Find a page
             */
            if ((mem = vm_page_lookup(object, offset)) == VM_PAGE_NULL)
                panic("kmem_remap_pages");

            /*
             *  Wire it down (again)
             */
            vm_page_lock_queues();
            vm_page_wire(mem);
            vm_page_unlock_queues();
            vm_object_unlock(object);

            /*
             *  Enter it in the kernel pmap.  The page isn't busy,
             *  but this shouldn't be a problem because it is wired.
             */
            PMAP_ENTER(kernel_pmap, start, mem, protection, 
                        ((unsigned int)(mem->object->wimg_bits))
                                        & VM_WIMG_MASK,
                        TRUE);

            start += PAGE_SIZE;
            offset += PAGE_SIZE;
        }
}

/*
 *      kmem_suballoc:
 *
 *      Allocates a map to manage a subrange
 *      of the kernel virtual address space.
 *
 *      Arguments are as follows:
 *
 *      parent          Map to take range from
 *      addr            Address of start of range (IN/OUT)
 *      size            Size of range to find
 *      pageable        Can region be paged
 *      anywhere        Can region be located anywhere in map
 *      new_map         Pointer to new submap
 */
kern_return_t
kmem_suballoc(
        vm_map_t        parent,
        vm_offset_t     *addr,
        vm_size_t       size,
        boolean_t       pageable,
        boolean_t       anywhere,
        vm_map_t        *new_map)
{
        vm_map_t map;
        kern_return_t kr;

        size = round_page_32(size);

        /*
         *      Need reference on submap object because it is internal
         *      to the vm_system.  vm_object_enter will never be called
         *      on it (usual source of reference for vm_map_enter).
         */
        vm_object_reference(vm_submap_object);

        if (anywhere == TRUE)
                *addr = (vm_offset_t)vm_map_min(parent);
        kr = vm_map_enter(parent, addr, size,
                          (vm_offset_t) 0, anywhere,
                          vm_submap_object, (vm_object_offset_t) 0, FALSE,
                          VM_PROT_DEFAULT, VM_PROT_ALL, VM_INHERIT_DEFAULT);
        if (kr != KERN_SUCCESS) {
                vm_object_deallocate(vm_submap_object);
                return (kr);
        }

        pmap_reference(vm_map_pmap(parent));
        map = vm_map_create(vm_map_pmap(parent), *addr, *addr + size, pageable);
        if (map == VM_MAP_NULL)
                panic("kmem_suballoc: vm_map_create failed");   /* "can't happen" */

        kr = vm_map_submap(parent, *addr, *addr + size, map, *addr, FALSE);
        if (kr != KERN_SUCCESS) {
                /*
                 * See comment preceding vm_map_submap().
                 */
                vm_map_remove(parent, *addr, *addr + size, VM_MAP_NO_FLAGS);
                vm_map_deallocate(map); /* also removes ref to pmap */
                vm_object_deallocate(vm_submap_object);
                return (kr);
        }
        *new_map = map;
        return (KERN_SUCCESS);
}

/*
 *      kmem_init:
 *
 *      Initialize the kernel's virtual memory map, taking
 *      into account all memory allocated up to this time.
 */
void
kmem_init(
        vm_offset_t     start,
        vm_offset_t     end)
{
        kernel_map = vm_map_create(pmap_kernel(),
                                   VM_MIN_KERNEL_ADDRESS, end,
                                   FALSE);

        /*
         *      Reserve virtual memory allocated up to this time.
         */

        if (start != VM_MIN_KERNEL_ADDRESS) {
                vm_offset_t addr = VM_MIN_KERNEL_ADDRESS;
                (void) vm_map_enter(kernel_map,
                                    &addr, start - VM_MIN_KERNEL_ADDRESS,
                                    (vm_offset_t) 0, TRUE,
                                    VM_OBJECT_NULL, 
                                    (vm_object_offset_t) 0, FALSE,
                                    VM_PROT_DEFAULT, VM_PROT_ALL,
                                    VM_INHERIT_DEFAULT);
        }

        /*
         * Account for kernel memory (text, data, bss, vm shenanigans).
         * This may include inaccessible "holes" as determined by what
         * the machine-dependent init code includes in max_mem.
         */
        vm_page_wire_count = (atop_64(max_mem) - (vm_page_free_count
                                                + vm_page_active_count
                                                + vm_page_inactive_count));
}


/*
 *      kmem_io_object_trunc:
 *
 *      Truncate an object vm_map_copy_t.
 *      Called by the scatter/gather list network code to remove pages from
 *      the tail end of a packet. Also unwires the objects pages.
 */

kern_return_t
kmem_io_object_trunc(copy, new_size)
     vm_map_copy_t      copy;           /* IN/OUT copy object */
     register vm_size_t new_size;       /* IN new object size */
{
        register vm_size_t      offset, old_size;

        assert(copy->type == VM_MAP_COPY_OBJECT);

        old_size = (vm_size_t)round_page_64(copy->size);
        copy->size = new_size;
        new_size = round_page_32(new_size);

        vm_object_lock(copy->cpy_object);
        vm_object_page_remove(copy->cpy_object,
                (vm_object_offset_t)new_size, (vm_object_offset_t)old_size);
        for (offset = 0; offset < new_size; offset += PAGE_SIZE) {
                register vm_page_t      mem;

                if ((mem = vm_page_lookup(copy->cpy_object, 
                                (vm_object_offset_t)offset)) == VM_PAGE_NULL)
                    panic("kmem_io_object_trunc: unable to find object page");

                /*
                 * Make sure these pages are marked dirty
                 */
                mem->dirty = TRUE;
                vm_page_lock_queues();
                vm_page_unwire(mem);
                vm_page_unlock_queues();
        }
        copy->cpy_object->size = new_size;      /*  adjust size of object */
        vm_object_unlock(copy->cpy_object);
        return(KERN_SUCCESS);
}

/*
 *      kmem_io_object_deallocate:
 *
 *      Free an vm_map_copy_t.
 *      Called by the scatter/gather list network code to free a packet.
 */

void
kmem_io_object_deallocate(
     vm_map_copy_t      copy)           /* IN/OUT copy object */
{
        kern_return_t   ret;

        /*
         * Clear out all the object pages (this will leave an empty object).
         */
        ret = kmem_io_object_trunc(copy, 0);
        if (ret != KERN_SUCCESS)
                panic("kmem_io_object_deallocate: unable to truncate object");
        /*
         * ...and discard the copy object.
         */
        vm_map_copy_discard(copy);
}

/*
 *      Routine:        copyinmap
 *      Purpose:
 *              Like copyin, except that fromaddr is an address
 *              in the specified VM map.  This implementation
 *              is incomplete; it handles the current user map
 *              and the kernel map/submaps.
 */
boolean_t
copyinmap(
        vm_map_t        map,
        vm_offset_t     fromaddr,
        vm_offset_t     toaddr,
        vm_size_t       length)
{
        if (vm_map_pmap(map) == pmap_kernel()) {
                /* assume a correct copy */
                memcpy((void *)toaddr, (void *)fromaddr, length);
                return FALSE;
        }

        if (current_map() == map)
                return copyin((char *)fromaddr, (char *)toaddr, length);

        return TRUE;
}

/*
 *      Routine:        copyoutmap
 *      Purpose:
 *              Like copyout, except that toaddr is an address
 *              in the specified VM map.  This implementation
 *              is incomplete; it handles the current user map
 *              and the kernel map/submaps.
 */
boolean_t
copyoutmap(
        vm_map_t        map,
        vm_offset_t     fromaddr,
        vm_offset_t     toaddr,
        vm_size_t       length)
{
        if (vm_map_pmap(map) == pmap_kernel()) {
                /* assume a correct copy */
                memcpy((void *)toaddr, (void *)fromaddr, length);
                return FALSE;
        }

        if (current_map() == map)
                return copyout((char *)fromaddr, (char *)toaddr, length);

        return TRUE;
}


kern_return_t
vm_conflict_check(
        vm_map_t                map,
        vm_offset_t             off,
        vm_size_t               len,
        memory_object_t         pager,
        vm_object_offset_t      file_off)
{
        vm_map_entry_t          entry;
        vm_object_t             obj;
        vm_object_offset_t      obj_off;
        vm_map_t                base_map;
        vm_offset_t             base_offset;
        vm_offset_t             original_offset;
        kern_return_t           kr;
        vm_size_t               local_len;

        base_map = map;
        base_offset = off;
        original_offset = off;
        kr = KERN_SUCCESS;
        vm_map_lock(map);
        while(vm_map_lookup_entry(map, off, &entry)) {
                local_len = len;

                if (entry->object.vm_object == VM_OBJECT_NULL) {
                        vm_map_unlock(map);
                        return KERN_SUCCESS;
                }
                if (entry->is_sub_map) {
                        vm_map_t        old_map;

                        old_map = map;
                        vm_map_lock(entry->object.sub_map);
                        map = entry->object.sub_map;
                        off = entry->offset + (off - entry->vme_start);
                        vm_map_unlock(old_map);
                        continue;
                }
                obj = entry->object.vm_object;
                obj_off = (off - entry->vme_start) + entry->offset;
                while(obj->shadow) {
                        obj_off += obj->shadow_offset;
                        obj = obj->shadow;
                }
                if((obj->pager_created) && (obj->pager == pager)) {
                        if(((obj->paging_offset) + obj_off) == file_off) {
                                if(off != base_offset) {
                                        vm_map_unlock(map);
                                        return KERN_FAILURE;
                                }
                                kr = KERN_ALREADY_WAITING;
                        } else {
                                vm_object_offset_t      obj_off_aligned;
                                vm_object_offset_t      file_off_aligned;

                                obj_off_aligned = obj_off & ~PAGE_MASK;
                                file_off_aligned = file_off & ~PAGE_MASK;

                                if (file_off_aligned == (obj->paging_offset + obj_off_aligned)) {
                                        /*
                                         * the target map and the file offset start in the same page
                                         * but are not identical... 
                                         */
                                        vm_map_unlock(map);
                                        return KERN_FAILURE;
                                }
                                if ((file_off < (obj->paging_offset + obj_off_aligned)) &&
                                    ((file_off + len) > (obj->paging_offset + obj_off_aligned))) {
                                        /*
                                         * some portion of the tail of the I/O will fall
                                         * within the encompass of the target map
                                         */
                                        vm_map_unlock(map);
                                        return KERN_FAILURE;
                                }
                                if ((file_off_aligned > (obj->paging_offset + obj_off)) &&
                                    (file_off_aligned < (obj->paging_offset + obj_off) + len)) {
                                        /*
                                         * the beginning page of the file offset falls within
                                         * the target map's encompass
                                         */
                                        vm_map_unlock(map);
                                        return KERN_FAILURE;
                                }
                        }
                } else if(kr != KERN_SUCCESS) {
                        vm_map_unlock(map);
                        return KERN_FAILURE;
                }

                if(len <= ((entry->vme_end - entry->vme_start) -
                                                (off - entry->vme_start))) {
                        vm_map_unlock(map);
                        return kr;
                } else {
                        len -= (entry->vme_end - entry->vme_start) -
                                                (off - entry->vme_start);
                }
                base_offset = base_offset + (local_len - len);
                file_off = file_off + (local_len - len);
                off = base_offset;
                if(map != base_map) {
                        vm_map_unlock(map);
                        vm_map_lock(base_map);
                        map = base_map;
                }
        }

        vm_map_unlock(map);
        return kr;
}