[apple/xnu.git] / iokit / Kernel / IOLib.cpp

/*
 * Copyright (c) 1998-2006 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,
 * 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@
 */
/*
 * HISTORY
 *
 * 17-Apr-91   Portions from libIO.m, Doug Mitchell at NeXT.
 * 17-Nov-98   cpp
 *
 */

#include <IOKit/system.h>
#include <mach/sync_policy.h>
#include <machine/machine_routines.h>
#include <vm/vm_kern.h>
#include <libkern/c++/OSCPPDebug.h>

#include <IOKit/assert.h>

#include <IOKit/IOReturn.h>
#include <IOKit/IOLib.h> 
#include <IOKit/IOLocks.h> 
#include <IOKit/IOMapper.h>
#include <IOKit/IOBufferMemoryDescriptor.h>
#include <IOKit/IOKitDebug.h> 

#include "IOKitKernelInternal.h"

#ifdef IOALLOCDEBUG
#include <libkern/OSDebug.h>
#include <sys/sysctl.h>
#endif

#include "libkern/OSAtomic.h"
#include <libkern/c++/OSKext.h>
#include <IOKit/IOStatisticsPrivate.h>
#include <sys/msgbuf.h>

#if IOKITSTATS

#define IOStatisticsAlloc(type, size) \
do { \
        IOStatistics::countAlloc(type, size); \
} while (0)

#else

#define IOStatisticsAlloc(type, size)

#endif /* IOKITSTATS */

extern "C"
{


mach_timespec_t IOZeroTvalspec = { 0, 0 };

extern ppnum_t pmap_find_phys(pmap_t pmap, addr64_t va);

extern int
__doprnt(
        const char              *fmt,
        va_list                 argp,
        void                    (*putc)(int, void *),
        void                    *arg,
        int                     radix);

extern void cons_putc_locked(char);
extern void bsd_log_lock(void);
extern void bsd_log_unlock(void);
extern void logwakeup();


/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

lck_grp_t       *IOLockGroup;

/*
 * Global variables for use by iLogger
 * These symbols are for use only by Apple diagnostic code.
 * Binary compatibility is not guaranteed for kexts that reference these symbols.
 */

void *_giDebugLogInternal       = NULL;
void *_giDebugLogDataInternal   = NULL;
void *_giDebugReserved1         = NULL;
void *_giDebugReserved2         = NULL;

iopa_t gIOBMDPageAllocator;

/*
 * Static variables for this module.
 */

static queue_head_t gIOMallocContiguousEntries;
static lck_mtx_t *  gIOMallocContiguousEntriesLock;

#if __x86_64__
enum { kIOMaxPageableMaps    = 8 };
enum { kIOPageableMapSize    = 512 * 1024 * 1024 };
enum { kIOPageableMaxMapSize = 512 * 1024 * 1024 };
#else
enum { kIOMaxPageableMaps    = 16 };
enum { kIOPageableMapSize    = 96 * 1024 * 1024 };
enum { kIOPageableMaxMapSize = 96 * 1024 * 1024 };
#endif

typedef struct {
    vm_map_t            map;
    vm_offset_t address;
    vm_offset_t end;
} IOMapData;

static struct {
    UInt32      count;
    UInt32      hint;
    IOMapData   maps[ kIOMaxPageableMaps ];
    lck_mtx_t * lock;
} gIOKitPageableSpace;

static iopa_t gIOPageablePageAllocator;

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

void IOLibInit(void)
{
    kern_return_t ret;

    static bool libInitialized;

    if(libInitialized)
        return; 

    gIOKitPageableSpace.maps[0].address = 0;
    ret = kmem_suballoc(kernel_map,
                    &gIOKitPageableSpace.maps[0].address,
                    kIOPageableMapSize,
                    TRUE,
                    VM_FLAGS_ANYWHERE,
                    &gIOKitPageableSpace.maps[0].map);
    if (ret != KERN_SUCCESS)
        panic("failed to allocate iokit pageable map\n");

    IOLockGroup = lck_grp_alloc_init("IOKit", LCK_GRP_ATTR_NULL);

    gIOKitPageableSpace.lock            = lck_mtx_alloc_init(IOLockGroup, LCK_ATTR_NULL);
    gIOKitPageableSpace.maps[0].end     = gIOKitPageableSpace.maps[0].address + kIOPageableMapSize;
    gIOKitPageableSpace.hint            = 0;
    gIOKitPageableSpace.count           = 1;

    gIOMallocContiguousEntriesLock      = lck_mtx_alloc_init(IOLockGroup, LCK_ATTR_NULL);
    queue_init( &gIOMallocContiguousEntries );

    iopa_init(&gIOBMDPageAllocator);
    iopa_init(&gIOPageablePageAllocator);

    libInitialized = true;
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

IOThread IOCreateThread(IOThreadFunc fcn, void *arg)
{
        kern_return_t   result;
        thread_t                thread;

        result = kernel_thread_start((thread_continue_t)fcn, arg, &thread);
        if (result != KERN_SUCCESS)
                return (NULL);

        thread_deallocate(thread);

        return (thread);
}


void IOExitThread(void)
{
    (void) thread_terminate(current_thread());
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */


void * IOMalloc(vm_size_t size)
{
    void * address;

    address = (void *)kalloc(size);
    if ( address ) {
#if IOALLOCDEBUG
                debug_iomalloc_size += size;
#endif
                IOStatisticsAlloc(kIOStatisticsMalloc, size);
    }

    return address;
}

void IOFree(void * address, vm_size_t size)
{
    if (address) {
                kfree(address, size);
#if IOALLOCDEBUG
                debug_iomalloc_size -= size;
#endif
                IOStatisticsAlloc(kIOStatisticsFree, size);
    }
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

void * IOMallocAligned(vm_size_t size, vm_size_t alignment)
{
    kern_return_t       kr;
    vm_offset_t         address;
    vm_offset_t         allocationAddress;
    vm_size_t           adjustedSize;
    uintptr_t           alignMask;

    if (size == 0)
        return 0;
    if (alignment == 0) 
        alignment = 1;

    alignMask = alignment - 1;
    adjustedSize = size + sizeof(vm_size_t) + sizeof(vm_address_t);

    if (size > adjustedSize) {
            address = 0;    /* overflow detected */
    }
    else if (adjustedSize >= page_size) {

        kr = kernel_memory_allocate(kernel_map, &address,
                                        size, alignMask, 0);
        if (KERN_SUCCESS != kr)
            address = 0;

    } else {

        adjustedSize += alignMask;

        if (adjustedSize >= page_size) {

            kr = kernel_memory_allocate(kernel_map, &allocationAddress,
                                            adjustedSize, 0, 0);
            if (KERN_SUCCESS != kr)
                allocationAddress = 0;

        } else
            allocationAddress = (vm_address_t) kalloc(adjustedSize);

        if (allocationAddress) {
            address = (allocationAddress + alignMask
                    + (sizeof(vm_size_t) + sizeof(vm_address_t)))
                    & (~alignMask);

            *((vm_size_t *)(address - sizeof(vm_size_t) - sizeof(vm_address_t))) 
                            = adjustedSize;
            *((vm_address_t *)(address - sizeof(vm_address_t)))
                            = allocationAddress;
        } else
            address = 0;
    }

    assert(0 == (address & alignMask));

    if( address) {
#if IOALLOCDEBUG
                debug_iomalloc_size += size;
#endif
        IOStatisticsAlloc(kIOStatisticsMallocAligned, size);
        }

    return (void *) address;
}

void IOFreeAligned(void * address, vm_size_t size)
{
    vm_address_t        allocationAddress;
    vm_size_t   adjustedSize;

    if( !address)
        return;

    assert(size);

    adjustedSize = size + sizeof(vm_size_t) + sizeof(vm_address_t);
    if (adjustedSize >= page_size) {

        kmem_free( kernel_map, (vm_offset_t) address, size);

    } else {
        adjustedSize = *((vm_size_t *)( (vm_address_t) address
                                - sizeof(vm_address_t) - sizeof(vm_size_t)));
        allocationAddress = *((vm_address_t *)( (vm_address_t) address
                                - sizeof(vm_address_t) ));

        if (adjustedSize >= page_size)
            kmem_free( kernel_map, allocationAddress, adjustedSize);
        else
          kfree((void *)allocationAddress, adjustedSize);
    }

#if IOALLOCDEBUG
    debug_iomalloc_size -= size;
#endif

    IOStatisticsAlloc(kIOStatisticsFreeAligned, size);
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

void
IOKernelFreePhysical(mach_vm_address_t address, mach_vm_size_t size)
{
    mach_vm_address_t allocationAddress;
    mach_vm_size_t    adjustedSize;

    if (!address)
        return;

    assert(size);

    adjustedSize = (2 * size) + sizeof(mach_vm_size_t) + sizeof(mach_vm_address_t);
    if (adjustedSize >= page_size) {

        kmem_free( kernel_map, (vm_offset_t) address, size);

    } else {

        adjustedSize = *((mach_vm_size_t *)
                        (address - sizeof(mach_vm_address_t) - sizeof(mach_vm_size_t)));
        allocationAddress = *((mach_vm_address_t *)
                        (address - sizeof(mach_vm_address_t) ));
        kfree((void *)allocationAddress, adjustedSize);
    }

    IOStatisticsAlloc(kIOStatisticsFreeContiguous, size);
#if IOALLOCDEBUG
    debug_iomalloc_size -= size;
#endif
}

mach_vm_address_t
IOKernelAllocateWithPhysicalRestrict(mach_vm_size_t size, mach_vm_address_t maxPhys, 
                                        mach_vm_size_t alignment, bool contiguous)
{
    kern_return_t       kr;
    mach_vm_address_t   address;
    mach_vm_address_t   allocationAddress;
    mach_vm_size_t      adjustedSize;
    mach_vm_address_t   alignMask;

    if (size == 0)
        return (0);
    if (alignment == 0) 
        alignment = 1;

    alignMask = alignment - 1;
    adjustedSize = (2 * size) + sizeof(mach_vm_size_t) + sizeof(mach_vm_address_t);

    contiguous = (contiguous && (adjustedSize > page_size))
                   || (alignment > page_size);

    if (contiguous || maxPhys)
    {
        int options = 0;
        vm_offset_t virt;

        adjustedSize = size;
        contiguous = (contiguous && (adjustedSize > page_size))
                           || (alignment > page_size);

        if (!contiguous)
        {
            if (maxPhys <= 0xFFFFFFFF)
            {
                maxPhys = 0;
                options |= KMA_LOMEM;
            }
            else if (gIOLastPage && (atop_64(maxPhys) > gIOLastPage))
            {
                maxPhys = 0;
            }
        }
        if (contiguous || maxPhys)
        {
            kr = kmem_alloc_contig(kernel_map, &virt, size,
                                   alignMask, atop(maxPhys), atop(alignMask), 0);
        }
        else
        {
            kr = kernel_memory_allocate(kernel_map, &virt,
                                        size, alignMask, options);
        }
        if (KERN_SUCCESS == kr)
            address = virt;
        else
            address = 0;
    }
    else
    {
        adjustedSize += alignMask;
        allocationAddress = (mach_vm_address_t) kalloc(adjustedSize);

        if (allocationAddress) {

            address = (allocationAddress + alignMask
                    + (sizeof(mach_vm_size_t) + sizeof(mach_vm_address_t)))
                    & (~alignMask);

            if (atop_32(address) != atop_32(address + size - 1))
                address = round_page(address);

            *((mach_vm_size_t *)(address - sizeof(mach_vm_size_t)
                            - sizeof(mach_vm_address_t))) = adjustedSize;
            *((mach_vm_address_t *)(address - sizeof(mach_vm_address_t)))
                            = allocationAddress;
        } else
            address = 0;
    }

    if (address) {
    IOStatisticsAlloc(kIOStatisticsMallocContiguous, size);
#if IOALLOCDEBUG
        debug_iomalloc_size += size;
#endif
    }

    return (address);
}


/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

struct _IOMallocContiguousEntry
{
    mach_vm_address_t          virtualAddr;
    IOBufferMemoryDescriptor * md;
    queue_chain_t              link;
};
typedef struct _IOMallocContiguousEntry _IOMallocContiguousEntry;

void * IOMallocContiguous(vm_size_t size, vm_size_t alignment,
                           IOPhysicalAddress * physicalAddress)
{
    mach_vm_address_t   address = 0;

    if (size == 0)
        return 0;
    if (alignment == 0) 
        alignment = 1;

    /* Do we want a physical address? */
    if (!physicalAddress)
    {
        address = IOKernelAllocateWithPhysicalRestrict(size, 0 /*maxPhys*/, alignment, true);
    }
    else do
    {
        IOBufferMemoryDescriptor * bmd;
        mach_vm_address_t          physicalMask;
        vm_offset_t                alignMask;

        alignMask = alignment - 1;
        physicalMask = (0xFFFFFFFF ^ alignMask);

        bmd = IOBufferMemoryDescriptor::inTaskWithPhysicalMask(
                kernel_task, kIOMemoryPhysicallyContiguous, size, physicalMask);
        if (!bmd)
            break;
        
        _IOMallocContiguousEntry *
        entry = IONew(_IOMallocContiguousEntry, 1);
        if (!entry)
        {
            bmd->release();
            break;
        }
        entry->virtualAddr = (mach_vm_address_t) bmd->getBytesNoCopy();
        entry->md          = bmd;
        lck_mtx_lock(gIOMallocContiguousEntriesLock);
        queue_enter( &gIOMallocContiguousEntries, entry, 
                    _IOMallocContiguousEntry *, link );
        lck_mtx_unlock(gIOMallocContiguousEntriesLock);

        address          = (mach_vm_address_t) entry->virtualAddr;
        *physicalAddress = bmd->getPhysicalAddress();
    }
    while (false);

    return (void *) address;
}

void IOFreeContiguous(void * _address, vm_size_t size)
{
    _IOMallocContiguousEntry * entry;
    IOMemoryDescriptor *       md = NULL;

    mach_vm_address_t address = (mach_vm_address_t) _address;

    if( !address)
        return;

    assert(size);

    lck_mtx_lock(gIOMallocContiguousEntriesLock);
    queue_iterate( &gIOMallocContiguousEntries, entry,
                    _IOMallocContiguousEntry *, link )
    {
        if( entry->virtualAddr == address ) {
            md   = entry->md;
            queue_remove( &gIOMallocContiguousEntries, entry,
                            _IOMallocContiguousEntry *, link );
            break;
        }
    }
    lck_mtx_unlock(gIOMallocContiguousEntriesLock);

    if (md)
    {
        md->release();
        IODelete(entry, _IOMallocContiguousEntry, 1);
    }
    else
    {
        IOKernelFreePhysical((mach_vm_address_t) address, size);
    }
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

kern_return_t IOIteratePageableMaps(vm_size_t size,
                    IOIteratePageableMapsCallback callback, void * ref)
{
    kern_return_t       kr = kIOReturnNotReady;
    vm_size_t           segSize;
    UInt32              attempts;
    UInt32              index;
    vm_offset_t         min;
    vm_map_t            map;

    if (size > kIOPageableMaxMapSize)
        return( kIOReturnBadArgument );

    do {
        index = gIOKitPageableSpace.hint;
        attempts = gIOKitPageableSpace.count;
        while( attempts--) {
            kr = (*callback)(gIOKitPageableSpace.maps[index].map, ref);
            if( KERN_SUCCESS == kr) {
                gIOKitPageableSpace.hint = index;
                break;
            }
            if( index)
                index--;
            else
                index = gIOKitPageableSpace.count - 1;
        }
        if( KERN_SUCCESS == kr)
            break;

        lck_mtx_lock( gIOKitPageableSpace.lock );

        index = gIOKitPageableSpace.count;
        if( index >= (kIOMaxPageableMaps - 1)) {
            lck_mtx_unlock( gIOKitPageableSpace.lock );
            break;
        }

        if( size < kIOPageableMapSize)
            segSize = kIOPageableMapSize;
        else
            segSize = size;

        min = 0;
        kr = kmem_suballoc(kernel_map,
                    &min,
                    segSize,
                    TRUE,
                    VM_FLAGS_ANYWHERE,
                    &map);
        if( KERN_SUCCESS != kr) {
            lck_mtx_unlock( gIOKitPageableSpace.lock );
            break;
        }

        gIOKitPageableSpace.maps[index].map     = map;
        gIOKitPageableSpace.maps[index].address = min;
        gIOKitPageableSpace.maps[index].end     = min + segSize;
        gIOKitPageableSpace.hint                = index;
        gIOKitPageableSpace.count               = index + 1;

        lck_mtx_unlock( gIOKitPageableSpace.lock );

    } while( true );

    return kr;
}

struct IOMallocPageableRef
{
    vm_offset_t address;
    vm_size_t    size;
};

static kern_return_t IOMallocPageableCallback(vm_map_t map, void * _ref)
{
    struct IOMallocPageableRef * ref = (struct IOMallocPageableRef *) _ref;
    kern_return_t                kr;

    kr = kmem_alloc_pageable( map, &ref->address, ref->size );

    return( kr );
}

static void * IOMallocPageablePages(vm_size_t size, vm_size_t alignment)
{
    kern_return_t              kr = kIOReturnNotReady;
    struct IOMallocPageableRef ref;

    if (alignment > page_size)
        return( 0 );
    if (size > kIOPageableMaxMapSize)
        return( 0 );

    ref.size = size;
    kr = IOIteratePageableMaps( size, &IOMallocPageableCallback, &ref );
    if( kIOReturnSuccess != kr)
        ref.address = 0;

    return( (void *) ref.address );
}

vm_map_t IOPageableMapForAddress( uintptr_t address )
{
    vm_map_t    map = 0;
    UInt32      index;
    
    for( index = 0; index < gIOKitPageableSpace.count; index++) {
        if( (address >= gIOKitPageableSpace.maps[index].address)
         && (address < gIOKitPageableSpace.maps[index].end) ) {
            map = gIOKitPageableSpace.maps[index].map;
            break;
        }
    }
    if( !map)
        panic("IOPageableMapForAddress: null");

    return( map );
}

static void IOFreePageablePages(void * address, vm_size_t size)
{
    vm_map_t map;
    
    map = IOPageableMapForAddress( (vm_address_t) address);
    if( map)
        kmem_free( map, (vm_offset_t) address, size);
}

static uintptr_t IOMallocOnePageablePage(iopa_t * a)
{
    return ((uintptr_t) IOMallocPageablePages(page_size, page_size));
}

void * IOMallocPageable(vm_size_t size, vm_size_t alignment)
{
    void * addr;

    if (size >= (page_size - 4*kIOPageAllocChunkBytes)) addr = IOMallocPageablePages(size, alignment);
    else                   addr = ((void * ) iopa_alloc(&gIOPageablePageAllocator, &IOMallocOnePageablePage, size, alignment));

    if (addr) {
#if IOALLOCDEBUG
       debug_iomallocpageable_size += size;
#endif
       IOStatisticsAlloc(kIOStatisticsMallocPageable, size);
    }

    return (addr);
}

void IOFreePageable(void * address, vm_size_t size)
{
#if IOALLOCDEBUG
    debug_iomallocpageable_size -= size;
#endif
    IOStatisticsAlloc(kIOStatisticsFreePageable, size);

    if (size < (page_size - 4*kIOPageAllocChunkBytes))
    {
        address = (void *) iopa_free(&gIOPageablePageAllocator, (uintptr_t) address, size);
        size = page_size;
    }
    if (address) IOFreePageablePages(address, size);
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

#if 0
#undef assert
#define assert(ex)  \
        ((ex) ? (void)0 : Assert(__FILE__, __LINE__, # ex))
#endif

typedef char iopa_page_t_assert[(sizeof(iopa_page_t) <= kIOPageAllocChunkBytes) ? 1 : -1];

extern "C" void 
iopa_init(iopa_t * a)
{
    bzero(a, sizeof(*a));
    a->lock = IOLockAlloc();
    queue_init(&a->list);
}

static uintptr_t
iopa_allocinpage(iopa_page_t * pa, uint32_t count, uint64_t align)
{
    uint32_t n, s;
    uint64_t avail = pa->avail;

    assert(avail);

    // find strings of count 1 bits in avail
    for (n = count; n > 1; n -= s)
    {
        s = n >> 1;
        avail = avail & (avail << s);
    }
    // and aligned
    avail &= align;

    if (avail)
    {
        n = __builtin_clzll(avail);
        pa->avail &= ~((-1ULL << (64 - count)) >> n);
        if (!pa->avail && pa->link.next)
        {
            remque(&pa->link);
            pa->link.next = 0;
        }
        return (n * kIOPageAllocChunkBytes + trunc_page((uintptr_t) pa));
    }

    return (0);
}

static uint32_t 
log2up(uint32_t size)
{
    if (size <= 1) size = 0;
    else size = 32 - __builtin_clz(size - 1);
    return (size);
}

uintptr_t 
iopa_alloc(iopa_t * a, iopa_proc_t alloc, vm_size_t bytes, uint32_t balign)
{
    static const uint64_t align_masks[] = {
        0xFFFFFFFFFFFFFFFF,
        0xAAAAAAAAAAAAAAAA,
        0x8888888888888888,
        0x8080808080808080,
        0x8000800080008000,
        0x8000000080000000,
        0x8000000000000000,
    };
    iopa_page_t * pa;
    uintptr_t     addr = 0;
    uint32_t      count;
    uint64_t      align;

    if (!bytes) bytes = 1;
    count = (bytes + kIOPageAllocChunkBytes - 1) / kIOPageAllocChunkBytes;
    align = align_masks[log2up((balign + kIOPageAllocChunkBytes - 1) / kIOPageAllocChunkBytes)];

    IOLockLock(a->lock);
    pa = (typeof(pa)) queue_first(&a->list);
    while (!queue_end(&a->list, &pa->link))
    {
        addr = iopa_allocinpage(pa, count, align);
        if (addr)
        {
            a->bytecount += bytes;
            break;
        }
        pa = (typeof(pa)) queue_next(&pa->link);
    }
    IOLockUnlock(a->lock);

    if (!addr)
    {
        addr = alloc(a);
        if (addr)
        {
            pa = (typeof(pa)) (addr + page_size - kIOPageAllocChunkBytes);
            pa->signature = kIOPageAllocSignature;
            pa->avail     = -2ULL;

            addr = iopa_allocinpage(pa, count, align);
            IOLockLock(a->lock);
            if (pa->avail) enqueue_head(&a->list, &pa->link);
            a->pagecount++;
            if (addr) a->bytecount += bytes;
            IOLockUnlock(a->lock);
        }
    }

    assert((addr & ((1 << log2up(balign)) - 1)) == 0);
    return (addr);
}

uintptr_t 
iopa_free(iopa_t * a, uintptr_t addr, vm_size_t bytes)
{
    iopa_page_t * pa;
    uint32_t      count;
    uintptr_t     chunk;

    if (!bytes) bytes = 1;

    chunk = (addr & page_mask);
    assert(0 == (chunk & (kIOPageAllocChunkBytes - 1)));

    pa = (typeof(pa)) (addr | (page_size - kIOPageAllocChunkBytes));
    assert(kIOPageAllocSignature == pa->signature);

    count = (bytes + kIOPageAllocChunkBytes - 1) / kIOPageAllocChunkBytes;
    chunk /= kIOPageAllocChunkBytes;

    IOLockLock(a->lock);
    if (!pa->avail)
    {
        assert(!pa->link.next);
        enqueue_tail(&a->list, &pa->link);
    }
    pa->avail |= ((-1ULL << (64 - count)) >> chunk);
    if (pa->avail != -2ULL) pa = 0;
    else
    {
        remque(&pa->link);
        pa->link.next = 0;
        pa->signature = 0;
        a->pagecount--;
        // page to free
        pa = (typeof(pa)) trunc_page(pa);
    }
    a->bytecount -= bytes;
    IOLockUnlock(a->lock);

    return ((uintptr_t) pa);
}
    
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

IOReturn IOSetProcessorCacheMode( task_t task, IOVirtualAddress address,
                                  IOByteCount length, IOOptionBits cacheMode )
{
    IOReturn    ret = kIOReturnSuccess;
    ppnum_t     pagenum;

    if( task != kernel_task)
        return( kIOReturnUnsupported );
    if ((address | length) & PAGE_MASK)
    {
//      OSReportWithBacktrace("IOSetProcessorCacheMode(0x%x, 0x%x, 0x%x) fails\n", address, length, cacheMode);
        return( kIOReturnUnsupported );
    }
    length = round_page(address + length) - trunc_page( address );
    address = trunc_page( address );

    // make map mode
    cacheMode = (cacheMode << kIOMapCacheShift) & kIOMapCacheMask;

    while( (kIOReturnSuccess == ret) && (length > 0) ) {

        // Get the physical page number
        pagenum = pmap_find_phys(kernel_pmap, (addr64_t)address);
        if( pagenum) {
            ret = IOUnmapPages( get_task_map(task), address, page_size );
            ret = IOMapPages( get_task_map(task), address, ptoa_64(pagenum), page_size, cacheMode );
        } else
            ret = kIOReturnVMError;

        address += page_size;
        length -= page_size;
    }

    return( ret );
}


IOReturn IOFlushProcessorCache( task_t task, IOVirtualAddress address,
                                  IOByteCount length )
{
    if( task != kernel_task)
        return( kIOReturnUnsupported );

    flush_dcache64( (addr64_t) address, (unsigned) length, false );

    return( kIOReturnSuccess );
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

vm_offset_t OSKernelStackRemaining( void )
{
    return (ml_stack_remaining());
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*
 * Spin for indicated number of milliseconds.
 */
void IOSleep(unsigned milliseconds)
{
    delay_for_interval(milliseconds, kMillisecondScale);
}

/*
 * Spin for indicated number of microseconds.
 */
void IODelay(unsigned microseconds)
{
    delay_for_interval(microseconds, kMicrosecondScale);
}

/*
 * Spin for indicated number of nanoseconds.
 */
void IOPause(unsigned nanoseconds)
{
    delay_for_interval(nanoseconds, kNanosecondScale);
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

static void _iolog_consputc(int ch, void *arg __unused)
{
    cons_putc_locked(ch);
}

static void _iolog_logputc(int ch, void *arg __unused)
{
    log_putc_locked(ch);
}

void IOLog(const char *format, ...)
{
    va_list ap;

    va_start(ap, format);
    IOLogv(format, ap);
    va_end(ap);
}

void IOLogv(const char *format, va_list ap)
{
    va_list ap2;

    va_copy(ap2, ap);

    bsd_log_lock();
    __doprnt(format, ap, _iolog_logputc, NULL, 16);
    bsd_log_unlock();
    logwakeup();

    __doprnt(format, ap2, _iolog_consputc, NULL, 16);
}

#if !__LP64__
void IOPanic(const char *reason)
{
        panic("%s", reason);
}
#endif

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*
 * Convert a integer constant (typically a #define or enum) to a string.
 */
static char noValue[80];        // that's pretty

const char *IOFindNameForValue(int value, const IONamedValue *regValueArray)
{
        for( ; regValueArray->name; regValueArray++) {
                if(regValueArray->value == value)
                        return(regValueArray->name);
        }
        snprintf(noValue, sizeof(noValue), "0x%x (UNDEFINED)", value);
        return((const char *)noValue);
}

IOReturn IOFindValueForName(const char *string, 
        const IONamedValue *regValueArray,
        int *value)
{
        for( ; regValueArray->name; regValueArray++) {
                if(!strcmp(regValueArray->name, string)) {
                        *value = regValueArray->value;
                        return kIOReturnSuccess;
                }
        }
        return kIOReturnBadArgument;
}

OSString * IOCopyLogNameForPID(int pid)
{
    char   buf[128];
    size_t len;
    snprintf(buf, sizeof(buf), "pid %d, ", pid);
    len = strlen(buf);
    proc_name(pid, buf + len, sizeof(buf) - len);
    return (OSString::withCString(buf));
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

IOAlignment IOSizeToAlignment(unsigned int size)
{
    register int shift;
    const int intsize = sizeof(unsigned int) * 8;
    
    for (shift = 1; shift < intsize; shift++) {
        if (size & 0x80000000)
            return (IOAlignment)(intsize - shift);
        size <<= 1;
    }
    return 0;
}

unsigned int IOAlignmentToSize(IOAlignment align)
{
    unsigned int size;
    
    for (size = 1; align; align--) {
        size <<= 1;
    }
    return size;
}

} /* extern "C" */