path: root/MdeModulePkg/Core/Dxe/Mem/Page.c

/** @file
  UEFI Memory page management functions.

Copyright (c) 2007 - 2008, Intel Corporation. <BR>
All rights reserved. This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution.  The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php

THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

**/

#include "DxeMain.h"
#include "Imem.h"

#define EFI_DEFAULT_PAGE_ALLOCATION_ALIGNMENT  (EFI_PAGE_SIZE)

//
// Entry for tracking the memory regions for each memory type to coalesce similar memory types
//
typedef struct {
  EFI_PHYSICAL_ADDRESS  BaseAddress;
  EFI_PHYSICAL_ADDRESS  MaximumAddress;
  UINT64                CurrentNumberOfPages;
  UINT64                NumberOfPages;
  UINTN                 InformationIndex;
  BOOLEAN               Special;
  BOOLEAN               Runtime;
} EFI_MEMORY_TYPE_STAISTICS;

//
// MemoryMap - The current memory map
//
UINTN     mMemoryMapKey = 0;

#define MAX_MAP_DEPTH 6

///
/// mMapDepth - depth of new descriptor stack
///
UINTN         mMapDepth = 0;
///
/// mMapStack - space to use as temp storage to build new map descriptors
///
MEMORY_MAP    mMapStack[MAX_MAP_DEPTH];
UINTN         mFreeMapStack = 0;
///
/// This list maintain the free memory map list
///
LIST_ENTRY   mFreeMemoryMapEntryList = INITIALIZE_LIST_HEAD_VARIABLE (mFreeMemoryMapEntryList);
BOOLEAN      mMemoryTypeInformationInitialized = FALSE;

EFI_MEMORY_TYPE_STAISTICS mMemoryTypeStatistics[EfiMaxMemoryType + 1] = {
  { 0, EFI_MAX_ADDRESS, 0, 0, EfiMaxMemoryType, TRUE,  FALSE },  // EfiReservedMemoryType
  { 0, EFI_MAX_ADDRESS, 0, 0, EfiMaxMemoryType, FALSE, FALSE },  // EfiLoaderCode
  { 0, EFI_MAX_ADDRESS, 0, 0, EfiMaxMemoryType, FALSE, FALSE },  // EfiLoaderData
  { 0, EFI_MAX_ADDRESS, 0, 0, EfiMaxMemoryType, FALSE, FALSE },  // EfiBootServicesCode
  { 0, EFI_MAX_ADDRESS, 0, 0, EfiMaxMemoryType, FALSE, FALSE },  // EfiBootServicesData
  { 0, EFI_MAX_ADDRESS, 0, 0, EfiMaxMemoryType, TRUE,  TRUE  },  // EfiRuntimeServicesCode
  { 0, EFI_MAX_ADDRESS, 0, 0, EfiMaxMemoryType, TRUE,  TRUE  },  // EfiRuntimeServicesData
  { 0, EFI_MAX_ADDRESS, 0, 0, EfiMaxMemoryType, FALSE, FALSE },  // EfiConventionalMemory
  { 0, EFI_MAX_ADDRESS, 0, 0, EfiMaxMemoryType, FALSE, FALSE },  // EfiUnusableMemory
  { 0, EFI_MAX_ADDRESS, 0, 0, EfiMaxMemoryType, TRUE,  FALSE },  // EfiACPIReclaimMemory
  { 0, EFI_MAX_ADDRESS, 0, 0, EfiMaxMemoryType, TRUE,  FALSE },  // EfiACPIMemoryNVS
  { 0, EFI_MAX_ADDRESS, 0, 0, EfiMaxMemoryType, FALSE, FALSE },  // EfiMemoryMappedIO
  { 0, EFI_MAX_ADDRESS, 0, 0, EfiMaxMemoryType, FALSE, FALSE },  // EfiMemoryMappedIOPortSpace
  { 0, EFI_MAX_ADDRESS, 0, 0, EfiMaxMemoryType, TRUE,  TRUE  },  // EfiPalCode
  { 0, EFI_MAX_ADDRESS, 0, 0, EfiMaxMemoryType, FALSE, FALSE }   // EfiMaxMemoryType
};

EFI_PHYSICAL_ADDRESS mDefaultMaximumAddress = EFI_MAX_ADDRESS;

EFI_MEMORY_TYPE_INFORMATION gMemoryTypeInformation[EfiMaxMemoryType + 1] = {
  { EfiReservedMemoryType,      0 },
  { EfiLoaderCode,              0 },
  { EfiLoaderData,              0 },
  { EfiBootServicesCode,        0 },
  { EfiBootServicesData,        0 },
  { EfiRuntimeServicesCode,     0 },
  { EfiRuntimeServicesData,     0 },
  { EfiConventionalMemory,      0 },
  { EfiUnusableMemory,          0 },
  { EfiACPIReclaimMemory,       0 },
  { EfiACPIMemoryNVS,           0 },
  { EfiMemoryMappedIO,          0 },
  { EfiMemoryMappedIOPortSpace, 0 },
  { EfiPalCode,                 0 },
  { EfiMaxMemoryType,           0 }
};


/**
  Enter critical section by gaining lock on gMemoryLock.

**/
VOID
CoreAcquireMemoryLock (
  VOID
  )
{
  CoreAcquireLock (&gMemoryLock);
}



/**
  Exit critical section by releasing lock on gMemoryLock.

**/
VOID
CoreReleaseMemoryLock (
  VOID
  )
{
  CoreReleaseLock (&gMemoryLock);
}




/**
  Internal function.  Removes a descriptor entry.

  @param  Entry                  The entry to remove

**/
VOID
RemoveMemoryMapEntry (
  IN OUT MEMORY_MAP      *Entry
  )
{
  RemoveEntryList (&Entry->Link);
  Entry->Link.ForwardLink = NULL;

  if (Entry->FromPages) {
    //
    // Insert the free memory map descriptor to the end of mFreeMemoryMapEntryList
    //
    InsertTailList (&mFreeMemoryMapEntryList, &Entry->Link);
  }
}

/**
  Internal function.  Adds a ranges to the memory map.
  The range must not already exist in the map.

  @param  Type                   The type of memory range to add
  @param  Start                  The starting address in the memory range Must be
                                 paged aligned
  @param  End                    The last address in the range Must be the last
                                 byte of a page
  @param  Attribute              The attributes of the memory range to add

**/
VOID
CoreAddRange (
  IN EFI_MEMORY_TYPE          Type,
  IN EFI_PHYSICAL_ADDRESS     Start,
  IN EFI_PHYSICAL_ADDRESS     End,
  IN UINT64                   Attribute
  )
{
  LIST_ENTRY        *Link;
  MEMORY_MAP        *Entry;

  ASSERT ((Start & EFI_PAGE_MASK) == 0);
  ASSERT (End > Start) ;

  ASSERT_LOCKED (&gMemoryLock);

  DEBUG ((DEBUG_PAGE, "AddRange: %lx-%lx to %d\n", Start, End, Type));

  //
  // Memory map being altered so updated key
  //
  mMemoryMapKey += 1;

  //
  // UEFI 2.0 added an event group for notificaiton on memory map changes.
  // So we need to signal this Event Group every time the memory map changes.
  // If we are in EFI 1.10 compatability mode no event groups will be
  // found and nothing will happen we we call this function. These events
  // will get signaled but since a lock is held around the call to this
  // function the notificaiton events will only be called after this funciton
  // returns and the lock is released.
  //
  CoreNotifySignalList (&gEfiEventMemoryMapChangeGuid);

  //
  // Look for adjoining memory descriptor
  //

  // Two memory descriptors can only be merged if they have the same Type
  // and the same Attribute
  //

  Link = gMemoryMap.ForwardLink;
  while (Link != &gMemoryMap) {
    Entry = CR (Link, MEMORY_MAP, Link, MEMORY_MAP_SIGNATURE);
    Link  = Link->ForwardLink;

    if (Entry->Type != Type) {
      continue;
    }

    if (Entry->Attribute != Attribute) {
      continue;
    }

    if (Entry->End + 1 == Start) {

      Start = Entry->Start;
      RemoveMemoryMapEntry (Entry);

    } else if (Entry->Start == End + 1) {

      End = Entry->End;
      RemoveMemoryMapEntry (Entry);
    }
  }

  //
  // Add descriptor
  //

  mMapStack[mMapDepth].Signature     = MEMORY_MAP_SIGNATURE;
  mMapStack[mMapDepth].FromPages      = FALSE;
  mMapStack[mMapDepth].Type          = Type;
  mMapStack[mMapDepth].Start         = Start;
  mMapStack[mMapDepth].End           = End;
  mMapStack[mMapDepth].VirtualStart  = 0;
  mMapStack[mMapDepth].Attribute     = Attribute;
  InsertTailList (&gMemoryMap, &mMapStack[mMapDepth].Link);

  mMapDepth += 1;
  ASSERT (mMapDepth < MAX_MAP_DEPTH);

  return ;
}

/**
  Internal function.  Deque a descriptor entry from the mFreeMemoryMapEntryList.
  If the list is emtry, then allocate a new page to refuel the list.
  Please Note this algorithm to allocate the memory map descriptor has a property
  that the memory allocated for memory entries always grows, and will never really be freed
  For example, if the current boot uses 2000 memory map entries at the maximum point, but
  ends up with only 50 at the time the OS is booted, then the memory associated with the 1950
  memory map entries is still allocated from EfiBootServicesMemory.


  @return The Memory map descriptor dequed from the mFreeMemoryMapEntryList

**/
MEMORY_MAP *
AllocateMemoryMapEntry (
  VOID
  )
{
  MEMORY_MAP*            FreeDescriptorEntries;
  MEMORY_MAP*            Entry;
  UINTN                  Index;

  if (IsListEmpty (&mFreeMemoryMapEntryList)) {
    //
    // The list is empty, to allocate one page to refuel the list
    //
    FreeDescriptorEntries = CoreAllocatePoolPages (EfiBootServicesData, EFI_SIZE_TO_PAGES(DEFAULT_PAGE_ALLOCATION), DEFAULT_PAGE_ALLOCATION);
    if(FreeDescriptorEntries != NULL) {
      //
      // Enque the free memmory map entries into the list
      //
      for (Index = 0; Index< DEFAULT_PAGE_ALLOCATION / sizeof(MEMORY_MAP); Index++) {
        FreeDescriptorEntries[Index].Signature = MEMORY_MAP_SIGNATURE;
        InsertTailList (&mFreeMemoryMapEntryList, &FreeDescriptorEntries[Index].Link);
      }
    } else {
      return NULL;
    }
  }
  //
  // dequeue the first descriptor from the list
  //
  Entry = CR (mFreeMemoryMapEntryList.ForwardLink, MEMORY_MAP, Link, MEMORY_MAP_SIGNATURE);
  RemoveEntryList (&Entry->Link);

  return Entry;
}


/**
  Internal function.  Moves any memory descriptors that are on the
  temporary descriptor stack to heap.

**/
VOID
CoreFreeMemoryMapStack (
  VOID
  )
{
  MEMORY_MAP      *Entry;
  MEMORY_MAP      *Entry2;
  LIST_ENTRY      *Link2;

  ASSERT_LOCKED (&gMemoryLock);

  //
  // If already freeing the map stack, then return
  //
  if (mFreeMapStack != 0) {
    return ;
  }

  //
  // Move the temporary memory descriptor stack into pool
  //
  mFreeMapStack += 1;

  while (mMapDepth != 0) {
    //
    // Deque an memory map entry from mFreeMemoryMapEntryList
    //
    Entry = AllocateMemoryMapEntry ();

    ASSERT (Entry);

    //
    // Update to proper entry
    //
    mMapDepth -= 1;

    if (mMapStack[mMapDepth].Link.ForwardLink != NULL) {

      //
      // Move this entry to general memory
      //
      RemoveEntryList (&mMapStack[mMapDepth].Link);
      mMapStack[mMapDepth].Link.ForwardLink = NULL;

      CopyMem (Entry , &mMapStack[mMapDepth], sizeof (MEMORY_MAP));
      Entry->FromPages = TRUE;

      //
      // Find insertion location
      //
      for (Link2 = gMemoryMap.ForwardLink; Link2 != &gMemoryMap; Link2 = Link2->ForwardLink) {
        Entry2 = CR (Link2, MEMORY_MAP, Link, MEMORY_MAP_SIGNATURE);
        if (Entry2->FromPages && Entry2->Start > Entry->Start) {
          break;
        }
      }

      InsertTailList (Link2, &Entry->Link);

    } else {
      //
      // This item of mMapStack[mMapDepth] has already been dequeued from gMemoryMap list,
      // so here no need to move it to memory.
      //
      InsertTailList (&mFreeMemoryMapEntryList, &Entry->Link);
    }
  }

  mFreeMapStack -= 1;
}

/**
  Find untested but initialized memory regions in GCD map and convert them to be DXE allocatable.

**/
VOID
PromoteMemoryResource (
  VOID
  )
{
  LIST_ENTRY                       *Link;
  EFI_GCD_MAP_ENTRY                *Entry;

  DEBUG ((DEBUG_PAGE, "Promote the memory resource\n"));

  CoreAcquireGcdMemoryLock ();

  Link = mGcdMemorySpaceMap.ForwardLink;
  while (Link != &mGcdMemorySpaceMap) {

    Entry = CR (Link, EFI_GCD_MAP_ENTRY, Link, EFI_GCD_MAP_SIGNATURE);

    if (Entry->GcdMemoryType == EfiGcdMemoryTypeReserved &&
        Entry->EndAddress < EFI_MAX_ADDRESS &&
        (Entry->Capabilities & (EFI_MEMORY_PRESENT | EFI_MEMORY_INITIALIZED | EFI_MEMORY_TESTED)) ==
          (EFI_MEMORY_PRESENT | EFI_MEMORY_INITIALIZED)) {
      //
      // Update the GCD map
      //
      Entry->GcdMemoryType = EfiGcdMemoryTypeSystemMemory;
      Entry->Capabilities |= EFI_MEMORY_TESTED;
      Entry->ImageHandle  = gDxeCoreImageHandle;
      Entry->DeviceHandle = NULL;

      //
      // Add to allocable system memory resource
      //

      CoreAddRange (
        EfiConventionalMemory,
        Entry->BaseAddress,
        Entry->EndAddress,
        Entry->Capabilities & ~(EFI_MEMORY_PRESENT | EFI_MEMORY_INITIALIZED | EFI_MEMORY_TESTED | EFI_MEMORY_RUNTIME)
        );
      CoreFreeMemoryMapStack ();

    }

    Link = Link->ForwardLink;
  }

  CoreReleaseGcdMemoryLock ();

  return;
}


/**
  Called to initialize the memory map and add descriptors to
  the current descriptor list.
  The first descriptor that is added must be general usable
  memory as the addition allocates heap.

  @param  Type                   The type of memory to add
  @param  Start                  The starting address in the memory range Must be
                                 page aligned
  @param  NumberOfPages          The number of pages in the range
  @param  Attribute              Attributes of the memory to add

  @return None.  The range is added to the memory map

**/
VOID
CoreAddMemoryDescriptor (
  IN EFI_MEMORY_TYPE       Type,
  IN EFI_PHYSICAL_ADDRESS  Start,
  IN UINT64                NumberOfPages,
  IN UINT64                Attribute
  )
{
  EFI_PHYSICAL_ADDRESS        End;
  EFI_STATUS                  Status;
  UINTN                       Index;
  UINTN                       FreeIndex;

  if ((Start & EFI_PAGE_MASK) != 0) {
    return;
  }

  if (Type >= EfiMaxMemoryType && Type <= 0x7fffffff) {
    return;
  }

  CoreAcquireMemoryLock ();
  End = Start + LShiftU64 (NumberOfPages, EFI_PAGE_SHIFT) - 1;
  CoreAddRange (Type, Start, End, Attribute);
  CoreFreeMemoryMapStack ();
  CoreReleaseMemoryLock ();

  //
  // Check to see if the statistics for the different memory types have already been established
  //
  if (mMemoryTypeInformationInitialized) {
    return;
  }

  //
  // Loop through each memory type in the order specified by the gMemoryTypeInformation[] array
  //
  for (Index = 0; gMemoryTypeInformation[Index].Type != EfiMaxMemoryType; Index++) {
    //
    // Make sure the memory type in the gMemoryTypeInformation[] array is valid
    //
    Type = (EFI_MEMORY_TYPE) (gMemoryTypeInformation[Index].Type);
    if (Type < 0 || Type > EfiMaxMemoryType) {
      continue;
    }

    if (gMemoryTypeInformation[Index].NumberOfPages != 0) {
      //
      // Allocate pages for the current memory type from the top of available memory
      //
      Status = CoreAllocatePages (
                 AllocateAnyPages,
                 Type,
                 gMemoryTypeInformation[Index].NumberOfPages,
                 &mMemoryTypeStatistics[Type].BaseAddress
                 );
      if (EFI_ERROR (Status)) {
        //
        // If an error occurs allocating the pages for the current memory type, then
        // free all the pages allocates for the previous memory types and return.  This
        // operation with be retied when/if more memory is added to the system
        //
        for (FreeIndex = 0; FreeIndex < Index; FreeIndex++) {
          //
          // Make sure the memory type in the gMemoryTypeInformation[] array is valid
          //
          Type = (EFI_MEMORY_TYPE) (gMemoryTypeInformation[FreeIndex].Type);
          if (Type < 0 || Type > EfiMaxMemoryType) {
            continue;
          }

          if (gMemoryTypeInformation[FreeIndex].NumberOfPages != 0) {
            CoreFreePages (
              mMemoryTypeStatistics[Type].BaseAddress,
              gMemoryTypeInformation[FreeIndex].NumberOfPages
              );
            mMemoryTypeStatistics[Type].BaseAddress    = 0;
            mMemoryTypeStatistics[Type].MaximumAddress = EFI_MAX_ADDRESS;
          }
        }
        return;
      }

      //
      // Compute the address at the top of the current statistics
      //
      mMemoryTypeStatistics[Type].MaximumAddress =
        mMemoryTypeStatistics[Type].BaseAddress +
        LShiftU64 (gMemoryTypeInformation[Index].NumberOfPages, EFI_PAGE_SHIFT) - 1;

      //
      // If the current base address is the lowest address so far, then update the default
      // maximum address
      //
      if (mMemoryTypeStatistics[Type].BaseAddress < mDefaultMaximumAddress) {
        mDefaultMaximumAddress = mMemoryTypeStatistics[Type].BaseAddress - 1;
      }
    }
  }

  //
  // There was enough system memory for all the the memory types were allocated.  So,
  // those memory areas can be freed for future allocations, and all future memory
  // allocations can occur within their respective bins
  //
  for (Index = 0; gMemoryTypeInformation[Index].Type != EfiMaxMemoryType; Index++) {
    //
    // Make sure the memory type in the gMemoryTypeInformation[] array is valid
    //
    Type = (EFI_MEMORY_TYPE) (gMemoryTypeInformation[Index].Type);
    if (Type < 0 || Type > EfiMaxMemoryType) {
      continue;
    }

    if (gMemoryTypeInformation[Index].NumberOfPages != 0) {
      CoreFreePages (
        mMemoryTypeStatistics[Type].BaseAddress,
        gMemoryTypeInformation[Index].NumberOfPages
        );
      mMemoryTypeStatistics[Type].NumberOfPages   = gMemoryTypeInformation[Index].NumberOfPages;
      gMemoryTypeInformation[Index].NumberOfPages = 0;
    }
  }

  //
  // If the number of pages reserved for a memory type is 0, then all allocations for that type
  // should be in the default range.
  //
  for (Type = (EFI_MEMORY_TYPE) 0; Type < EfiMaxMemoryType; Type++) {
    for (Index = 0; gMemoryTypeInformation[Index].Type != EfiMaxMemoryType; Index++) {
      if (Type == (EFI_MEMORY_TYPE)gMemoryTypeInformation[Index].Type) {
        mMemoryTypeStatistics[Type].InformationIndex = Index;
      }
    }
    mMemoryTypeStatistics[Type].CurrentNumberOfPages = 0;
    if (mMemoryTypeStatistics[Type].MaximumAddress == EFI_MAX_ADDRESS) {
      mMemoryTypeStatistics[Type].MaximumAddress = mDefaultMaximumAddress;
    }
  }

  mMemoryTypeInformationInitialized = TRUE;
}


/**
  Internal function.  Converts a memory range to the specified type.
  The range must exist in the memory map.

  @param  Start                  The first address of the range Must be page
                                 aligned
  @param  NumberOfPages          The number of pages to convert
  @param  NewType                The new type for the memory range

  @retval EFI_INVALID_PARAMETER  Invalid parameter
  @retval EFI_NOT_FOUND          Could not find a descriptor cover the specified
                                 range  or convertion not allowed.
  @retval EFI_SUCCESS            Successfully converts the memory range to the
                                 specified type.

**/
EFI_STATUS
CoreConvertPages (
  IN UINT64           Start,
  IN UINT64           NumberOfPages,
  IN EFI_MEMORY_TYPE  NewType
  )
{

  UINT64          NumberOfBytes;
  UINT64          End;
  UINT64          RangeEnd;
  UINT64          Attribute;
  LIST_ENTRY      *Link;
  MEMORY_MAP      *Entry;

  Entry = NULL;
  NumberOfBytes = LShiftU64 (NumberOfPages, EFI_PAGE_SHIFT);
  End = Start + NumberOfBytes - 1;

  ASSERT (NumberOfPages);
  ASSERT ((Start & EFI_PAGE_MASK) == 0);
  ASSERT (End > Start) ;
  ASSERT_LOCKED (&gMemoryLock);

  if (NumberOfPages == 0 || ((Start & EFI_PAGE_MASK) != 0) || (Start > (Start + NumberOfBytes))) {
    return EFI_INVALID_PARAMETER;
  }

  //
  // Convert the entire range
  //

  while (Start < End) {

    //
    // Find the entry that the covers the range
    //
    for (Link = gMemoryMap.ForwardLink; Link != &gMemoryMap; Link = Link->ForwardLink) {
      Entry = CR (Link, MEMORY_MAP, Link, MEMORY_MAP_SIGNATURE);

      if (Entry->Start <= Start && Entry->End > Start) {
        break;
      }
    }

    if (Link == &gMemoryMap) {
      DEBUG ((DEBUG_ERROR | DEBUG_PAGE, "ConvertPages: failed to find range %lx - %lx\n", Start, End));
      return EFI_NOT_FOUND;
    }

    //
    // Convert range to the end, or to the end of the descriptor
    // if that's all we've got
    //
    RangeEnd = End;
    if (Entry->End < End) {
      RangeEnd = Entry->End;
    }

    DEBUG ((DEBUG_PAGE, "ConvertRange: %lx-%lx to %d\n", Start, RangeEnd, NewType));

    //
    // Debug code - verify conversion is allowed
    //
    if (!(NewType == EfiConventionalMemory ? 1 : 0) ^ (Entry->Type == EfiConventionalMemory ? 1 : 0)) {
      DEBUG ((DEBUG_ERROR | DEBUG_PAGE, "ConvertPages: Incompatible memory types\n"));
      return EFI_NOT_FOUND;
    }

    //
    // Update counters for the number of pages allocated to each memory type
    //
    if (Entry->Type >= 0 && Entry->Type < EfiMaxMemoryType) {
      if (Start >= mMemoryTypeStatistics[Entry->Type].BaseAddress &&
          Start <= mMemoryTypeStatistics[Entry->Type].MaximumAddress) {
        if (NumberOfPages > mMemoryTypeStatistics[Entry->Type].CurrentNumberOfPages) {
          mMemoryTypeStatistics[Entry->Type].CurrentNumberOfPages = 0;
        } else {
          mMemoryTypeStatistics[Entry->Type].CurrentNumberOfPages -= NumberOfPages;
        }
      }
    }

    if (NewType >= 0 && NewType < EfiMaxMemoryType) {
      if (Start >= mMemoryTypeStatistics[NewType].BaseAddress && Start <= mMemoryTypeStatistics[NewType].MaximumAddress) {
        mMemoryTypeStatistics[NewType].CurrentNumberOfPages += NumberOfPages;
        if (mMemoryTypeStatistics[NewType].CurrentNumberOfPages >
            gMemoryTypeInformation[mMemoryTypeStatistics[NewType].InformationIndex].NumberOfPages) {
          gMemoryTypeInformation[mMemoryTypeStatistics[NewType].InformationIndex].NumberOfPages = (UINT32)mMemoryTypeStatistics[NewType].CurrentNumberOfPages;
        }
      }
    }

    //
    // Pull range out of descriptor
    //
    if (Entry->Start == Start) {

      //
      // Clip start
      //
      Entry->Start = RangeEnd + 1;

    } else if (Entry->End == RangeEnd) {

      //
      // Clip end
      //
      Entry->End = Start - 1;

    } else {

      //
      // Pull it out of the center, clip current
      //

      //
      // Add a new one
      //
      mMapStack[mMapDepth].Signature = MEMORY_MAP_SIGNATURE;
      mMapStack[mMapDepth].FromPages  = FALSE;
      mMapStack[mMapDepth].Type      = Entry->Type;
      mMapStack[mMapDepth].Start     = RangeEnd+1;
      mMapStack[mMapDepth].End       = Entry->End;

      //
      // Inherit Attribute from the Memory Descriptor that is being clipped
      //
      mMapStack[mMapDepth].Attribute = Entry->Attribute;

      Entry->End = Start - 1;
      ASSERT (Entry->Start < Entry->End);

      Entry = &mMapStack[mMapDepth];
      InsertTailList (&gMemoryMap, &Entry->Link);

      mMapDepth += 1;
      ASSERT (mMapDepth < MAX_MAP_DEPTH);
    }

    //
    // The new range inherits the same Attribute as the Entry
    //it is being cut out of
    //
    Attribute = Entry->Attribute;

    //
    // If the descriptor is empty, then remove it from the map
    //
    if (Entry->Start == Entry->End + 1) {
      RemoveMemoryMapEntry (Entry);
      Entry = NULL;
    }

    //
    // Add our new range in
    //
    CoreAddRange (NewType, Start, RangeEnd, Attribute);

    //
    // Move any map descriptor stack to general pool
    //
    CoreFreeMemoryMapStack ();

    //
    // Bump the starting address, and convert the next range
    //
    Start = RangeEnd + 1;
  }

  //
  // Converted the whole range, done
  //

  return EFI_SUCCESS;
}



/**
  Internal function. Finds a consecutive free page range below
  the requested address.

  @param  MaxAddress             The address that the range must be below
  @param  NumberOfPages          Number of pages needed
  @param  NewType                The type of memory the range is going to be
                                 turned into
  @param  Alignment              Bits to align with

  @return The base address of the range, or 0 if the range was not found

**/
UINT64
CoreFindFreePagesI (
  IN UINT64           MaxAddress,
  IN UINT64           NumberOfPages,
  IN EFI_MEMORY_TYPE  NewType,
  IN UINTN            Alignment
  )
{
  UINT64          NumberOfBytes;
  UINT64          Target;
  UINT64          DescStart;
  UINT64          DescEnd;
  UINT64          DescNumberOfBytes;
  LIST_ENTRY      *Link;
  MEMORY_MAP      *Entry;

  if ((MaxAddress < EFI_PAGE_MASK) ||(NumberOfPages == 0)) {
    return 0;
  }

  if ((MaxAddress & EFI_PAGE_MASK) != EFI_PAGE_MASK) {

    //
    // If MaxAddress is not aligned to the end of a page
    //

    //
    // Change MaxAddress to be 1 page lower
    //
    MaxAddress -= (EFI_PAGE_MASK + 1);

    //
    // Set MaxAddress to a page boundary
    //
    MaxAddress &= ~EFI_PAGE_MASK;

    //
    // Set MaxAddress to end of the page
    //
    MaxAddress |= EFI_PAGE_MASK;
  }

  NumberOfBytes = LShiftU64 (NumberOfPages, EFI_PAGE_SHIFT);
  Target = 0;

  for (Link = gMemoryMap.ForwardLink; Link != &gMemoryMap; Link = Link->ForwardLink) {
    Entry = CR (Link, MEMORY_MAP, Link, MEMORY_MAP_SIGNATURE);

    //
    // If it's not a free entry, don't bother with it
    //
    if (Entry->Type != EfiConventionalMemory) {
      continue;
    }

    DescStart = Entry->Start;
    DescEnd = Entry->End;

    //
    // If desc is past max allowed address, skip it
    //
    if (DescStart >= MaxAddress) {
      continue;
    }

    //
    // If desc ends past max allowed address, clip the end
    //
    if (DescEnd >= MaxAddress) {
      DescEnd = MaxAddress;
    }

    DescEnd = ((DescEnd + 1) & (~(Alignment - 1))) - 1;

    //
    // Compute the number of bytes we can used from this
    // descriptor, and see it's enough to satisfy the request
    //
    DescNumberOfBytes = DescEnd - DescStart + 1;

    if (DescNumberOfBytes >= NumberOfBytes) {

      //
      // If this is the best match so far remember it
      //
      if (DescEnd > Target) {
        Target = DescEnd;
      }
    }
  }

  //
  // If this is a grow down, adjust target to be the allocation base
  //
  Target -= NumberOfBytes - 1;

  //
  // If we didn't find a match, return 0
  //
  if ((Target & EFI_PAGE_MASK) != 0) {
    return 0;
  }

  return Target;
}


/**
  Internal function.  Finds a consecutive free page range below
  the requested address

  @param  MaxAddress             The address that the range must be below
  @param  NoPages                Number of pages needed
  @param  NewType                The type of memory the range is going to be
                                 turned into
  @param  Alignment              Bits to align with

  @return The base address of the range, or 0 if the range was not found.

**/
UINT64
FindFreePages (
    IN UINT64           MaxAddress,
    IN UINT64           NoPages,
    IN EFI_MEMORY_TYPE  NewType,
    IN UINTN            Alignment
    )
{
  UINT64  NewMaxAddress;
  UINT64  Start;

  NewMaxAddress = MaxAddress;

  if (NewType >= 0 && NewType < EfiMaxMemoryType && NewMaxAddress >= mMemoryTypeStatistics[NewType].MaximumAddress) {
    NewMaxAddress  = mMemoryTypeStatistics[NewType].MaximumAddress;
  } else {
    if (NewMaxAddress > mDefaultMaximumAddress) {
      NewMaxAddress  = mDefaultMaximumAddress;
    }
  }

  Start = CoreFindFreePagesI (NewMaxAddress, NoPages, NewType, Alignment);
  if (Start == 0) {
    Start = CoreFindFreePagesI (MaxAddress, NoPages, NewType, Alignment);
    if (Start == 0) {
      //
      // Here means there may be no enough memory to use, so try to go through
      // all the memory descript to promote the untested memory directly
      //
      PromoteMemoryResource ();

      //
      // Allocate memory again after the memory resource re-arranged
      //
      Start = CoreFindFreePagesI (MaxAddress, NoPages, NewType, Alignment);
    }
  }

  return Start;
}



/**
  Allocates pages from the memory map.

  @param  Type                   The type of allocation to perform
  @param  MemoryType             The type of memory to turn the allocated pages
                                 into
  @param  NumberOfPages          The number of pages to allocate
  @param  Memory                 A pointer to receive the base allocated memory
                                 address

  @return Status. On success, Memory is filled in with the base address allocated
  @retval EFI_INVALID_PARAMETER  Parameters violate checking rules defined in
                                 spec.
  @retval EFI_NOT_FOUND          Could not allocate pages match the requirement.
  @retval EFI_OUT_OF_RESOURCES   No enough pages to allocate.
  @retval EFI_SUCCESS            Pages successfully allocated.

**/
EFI_STATUS
EFIAPI
CoreAllocatePages (
  IN EFI_ALLOCATE_TYPE      Type,
  IN EFI_MEMORY_TYPE        MemoryType,
  IN UINTN                  NumberOfPages,
  IN OUT EFI_PHYSICAL_ADDRESS  *Memory
  )
{
  EFI_STATUS      Status;
  UINT64          Start;
  UINT64          MaxAddress;
  UINTN           Alignment;

  if (Type < AllocateAnyPages || Type >= (UINTN) MaxAllocateType) {
    return EFI_INVALID_PARAMETER;
  }

  if ((MemoryType >= EfiMaxMemoryType && MemoryType <= 0x7fffffff) ||
       MemoryType == EfiConventionalMemory) {
    return EFI_INVALID_PARAMETER;
  }

  Alignment = EFI_DEFAULT_PAGE_ALLOCATION_ALIGNMENT;

  if  (MemoryType == EfiACPIReclaimMemory   ||
       MemoryType == EfiACPIMemoryNVS       ||
       MemoryType == EfiRuntimeServicesCode ||
       MemoryType == EfiRuntimeServicesData) {

    Alignment = EFI_ACPI_RUNTIME_PAGE_ALLOCATION_ALIGNMENT;
  }

  if (Type == AllocateAddress) {
    if ((*Memory & (Alignment - 1)) != 0) {
      return EFI_NOT_FOUND;
    }
  }

  NumberOfPages += EFI_SIZE_TO_PAGES (Alignment) - 1;
  NumberOfPages &= ~(EFI_SIZE_TO_PAGES (Alignment) - 1);

  //
  // If this is for below a particular address, then
  //
  Start = *Memory;

  //
  // The max address is the max natively addressable address for the processor
  //
  MaxAddress = EFI_MAX_ADDRESS;

  if (Type == AllocateMaxAddress) {
    MaxAddress = Start;
  }

  CoreAcquireMemoryLock ();

  //
  // If not a specific address, then find an address to allocate
  //
  if (Type != AllocateAddress) {
    Start = FindFreePages (MaxAddress, NumberOfPages, MemoryType, Alignment);
    if (Start == 0) {
      Status = EFI_OUT_OF_RESOURCES;
      goto Done;
    }
  }

  //
  // Convert pages from FreeMemory to the requested type
  //
  Status = CoreConvertPages (Start, NumberOfPages, MemoryType);

Done:
  CoreReleaseMemoryLock ();

  if (!EFI_ERROR (Status)) {
    *Memory = Start;
  }

  return Status;
}


/**
  Frees previous allocated pages.

  @param  Memory                 Base address of memory being freed
  @param  NumberOfPages          The number of pages to free

  @retval EFI_NOT_FOUND          Could not find the entry that covers the range
  @retval EFI_INVALID_PARAMETER  Address not aligned
  @return EFI_SUCCESS         -Pages successfully freed.

**/
EFI_STATUS
EFIAPI
CoreFreePages (
  IN EFI_PHYSICAL_ADDRESS   Memory,
  IN UINTN                  NumberOfPages
  )
{
  EFI_STATUS      Status;
  LIST_ENTRY      *Link;
  MEMORY_MAP      *Entry;
  UINTN           Alignment;

  //
  // Free the range
  //
  CoreAcquireMemoryLock ();

  //
  // Find the entry that the covers the range
  //
  Entry = NULL;
  for (Link = gMemoryMap.ForwardLink; Link != &gMemoryMap; Link = Link->ForwardLink) {
    Entry = CR(Link, MEMORY_MAP, Link, MEMORY_MAP_SIGNATURE);
    if (Entry->Start <= Memory && Entry->End > Memory) {
        break;
    }
  }
  if (Link == &gMemoryMap) {
    CoreReleaseMemoryLock ();
    return EFI_NOT_FOUND;
  }

  Alignment = EFI_DEFAULT_PAGE_ALLOCATION_ALIGNMENT;

  if  (Entry->Type == EfiACPIReclaimMemory   ||
       Entry->Type == EfiACPIMemoryNVS       ||
       Entry->Type == EfiRuntimeServicesCode ||
       Entry->Type == EfiRuntimeServicesData) {

    Alignment = EFI_ACPI_RUNTIME_PAGE_ALLOCATION_ALIGNMENT;

  }

  if ((Memory & (Alignment - 1)) != 0) {
    CoreReleaseMemoryLock ();
    return EFI_INVALID_PARAMETER;
  }

  NumberOfPages += EFI_SIZE_TO_PAGES (Alignment) - 1;
  NumberOfPages &= ~(EFI_SIZE_TO_PAGES (Alignment) - 1);

  Status = CoreConvertPages (Memory, NumberOfPages, EfiConventionalMemory);

  CoreReleaseMemoryLock ();

  if (EFI_ERROR (Status)) {
    return Status;
  }

  //
  // Destroy the contents
  //
  if (Memory < EFI_MAX_ADDRESS) {
    DEBUG_CLEAR_MEMORY ((VOID *)(UINTN)Memory, NumberOfPages << EFI_PAGE_SHIFT);
  }

  return Status;
}


/**
  This function returns a copy of the current memory map. The map is an array of
  memory descriptors, each of which describes a contiguous block of memory.

  @param  MemoryMapSize          A pointer to the size, in bytes, of the
                                 MemoryMap buffer. On input, this is the size of
                                 the buffer allocated by the caller.  On output,
                                 it is the size of the buffer returned by the
                                 firmware  if the buffer was large enough, or the
                                 size of the buffer needed  to contain the map if
                                 the buffer was too small.
  @param  MemoryMap              A pointer to the buffer in which firmware places
                                 the current memory map.
  @param  MapKey                 A pointer to the location in which firmware
                                 returns the key for the current memory map.
  @param  DescriptorSize         A pointer to the location in which firmware
                                 returns the size, in bytes, of an individual
                                 EFI_MEMORY_DESCRIPTOR.
  @param  DescriptorVersion      A pointer to the location in which firmware
                                 returns the version number associated with the
                                 EFI_MEMORY_DESCRIPTOR.

  @retval EFI_SUCCESS            The memory map was returned in the MemoryMap
                                 buffer.
  @retval EFI_BUFFER_TOO_SMALL   The MemoryMap buffer was too small. The current
                                 buffer size needed to hold the memory map is
                                 returned in MemoryMapSize.
  @retval EFI_INVALID_PARAMETER  One of the parameters has an invalid value.

**/
EFI_STATUS
EFIAPI
CoreGetMemoryMap (
  IN OUT UINTN                  *MemoryMapSize,
  IN OUT EFI_MEMORY_DESCRIPTOR  *MemoryMap,
  OUT UINTN                     *MapKey,
  OUT UINTN                     *DescriptorSize,
  OUT UINT32                    *DescriptorVersion
  )
{
  EFI_STATUS                        Status;
  UINTN                             Size;
  UINTN                             BufferSize;
  UINTN                             NumberOfRuntimeEntries;
  LIST_ENTRY                        *Link;
  MEMORY_MAP                        *Entry;
  EFI_GCD_MAP_ENTRY                 *GcdMapEntry;
  EFI_MEMORY_TYPE                   Type;

  //
  // Make sure the parameters are valid
  //
  if (MemoryMapSize == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  CoreAcquireGcdMemoryLock ();

  //
  // Count the number of Reserved and MMIO entries that are marked for runtime use
  //
  NumberOfRuntimeEntries = 0;
  for (Link = mGcdMemorySpaceMap.ForwardLink; Link != &mGcdMemorySpaceMap; Link = Link->ForwardLink) {
    GcdMapEntry = CR (Link, EFI_GCD_MAP_ENTRY, Link, EFI_GCD_MAP_SIGNATURE);
    if ((GcdMapEntry->GcdMemoryType == EfiGcdMemoryTypeReserved) ||
        (GcdMapEntry->GcdMemoryType == EfiGcdMemoryTypeMemoryMappedIo)) {
      if ((GcdMapEntry->Attributes & EFI_MEMORY_RUNTIME) == EFI_MEMORY_RUNTIME) {
        NumberOfRuntimeEntries++;
      }
    }
  }

  Size = sizeof (EFI_MEMORY_DESCRIPTOR);

  //
  // Make sure Size != sizeof(EFI_MEMORY_DESCRIPTOR). This will
  // prevent people from having pointer math bugs in their code.
  // now you have to use *DescriptorSize to make things work.
  //
  Size += sizeof(UINT64) - (Size % sizeof (UINT64));

  if (DescriptorSize != NULL) {
    *DescriptorSize = Size;
  }

  if (DescriptorVersion != NULL) {
    *DescriptorVersion = EFI_MEMORY_DESCRIPTOR_VERSION;
  }

  CoreAcquireMemoryLock ();

  //
  // Compute the buffer size needed to fit the entire map
  //
  BufferSize = Size * NumberOfRuntimeEntries;
  for (Link = gMemoryMap.ForwardLink; Link != &gMemoryMap; Link = Link->ForwardLink) {
    BufferSize += Size;
  }

  if (*MemoryMapSize < BufferSize) {
    Status = EFI_BUFFER_TOO_SMALL;
    goto Done;
  }

  if (MemoryMap == NULL) {
    Status = EFI_INVALID_PARAMETER;
    goto Done;
  }

  //
  // Build the map
  //
  ZeroMem (MemoryMap, BufferSize);
  for (Link = gMemoryMap.ForwardLink; Link != &gMemoryMap; Link = Link->ForwardLink) {
    Entry = CR (Link, MEMORY_MAP, Link, MEMORY_MAP_SIGNATURE);
    ASSERT (Entry->VirtualStart == 0);

    //
    // Convert internal map into an EFI_MEMORY_DESCRIPTOR
    //
    MemoryMap->Type           = Entry->Type;
    MemoryMap->PhysicalStart  = Entry->Start;
    MemoryMap->VirtualStart   = Entry->VirtualStart;
    MemoryMap->NumberOfPages  = RShiftU64 (Entry->End - Entry->Start + 1, EFI_PAGE_SHIFT);
    //
    // If the memory type is EfiConventionalMemory, then determine if the range is part of a
    // memory type bin and needs to be converted to the same memory type as the rest of the
    // memory type bin in order to minimize EFI Memory Map changes across reboots.  This
    // improves the chances for a successful S4 resume in the presence of minor page allocation
    // differences across reboots.
    //
    if (MemoryMap->Type == EfiConventionalMemory) {
      for (Type = (EFI_MEMORY_TYPE) 0; Type < EfiMaxMemoryType; Type++) {
        if (mMemoryTypeStatistics[Type].Special                        &&
            mMemoryTypeStatistics[Type].NumberOfPages > 0              &&
            Entry->Start >= mMemoryTypeStatistics[Type].BaseAddress    &&
            Entry->End   <= mMemoryTypeStatistics[Type].MaximumAddress) {
          MemoryMap->Type = Type;
        }
      }
    }
    MemoryMap->Attribute = Entry->Attribute;
    if (mMemoryTypeStatistics[MemoryMap->Type].Runtime) {
      MemoryMap->Attribute |= EFI_MEMORY_RUNTIME;
    }

    MemoryMap = NextMemoryDescriptor (MemoryMap, Size);
  }

  for (Link = mGcdMemorySpaceMap.ForwardLink; Link != &mGcdMemorySpaceMap; Link = Link->ForwardLink) {
    GcdMapEntry = CR (Link, EFI_GCD_MAP_ENTRY, Link, EFI_GCD_MAP_SIGNATURE);
    if ((GcdMapEntry->GcdMemoryType == EfiGcdMemoryTypeReserved) ||
        (GcdMapEntry->GcdMemoryType == EfiGcdMemoryTypeMemoryMappedIo)) {
      if ((GcdMapEntry->Attributes & EFI_MEMORY_RUNTIME) == EFI_MEMORY_RUNTIME) {
        // 
        // Create EFI_MEMORY_DESCRIPTOR for every Reserved and MMIO GCD entries
        // that are marked for runtime use
        //
        MemoryMap->PhysicalStart = GcdMapEntry->BaseAddress;
        MemoryMap->VirtualStart  = 0;
        MemoryMap->NumberOfPages = RShiftU64 ((GcdMapEntry->EndAddress - GcdMapEntry->BaseAddress + 1), EFI_PAGE_SHIFT);
        MemoryMap->Attribute     = GcdMapEntry->Attributes & ~EFI_MEMORY_PORT_IO;

        if (GcdMapEntry->GcdMemoryType == EfiGcdMemoryTypeReserved) {
          MemoryMap->Type = EfiReservedMemoryType;
        } else if (GcdMapEntry->GcdMemoryType == EfiGcdMemoryTypeMemoryMappedIo) {
          if ((GcdMapEntry->Attributes & EFI_MEMORY_PORT_IO) == EFI_MEMORY_PORT_IO) {
            MemoryMap->Type = EfiMemoryMappedIOPortSpace;
          } else {
            MemoryMap->Type = EfiMemoryMappedIO;
          }
        }

        MemoryMap = NextMemoryDescriptor (MemoryMap, Size);
      }
    }
  }

  Status = EFI_SUCCESS;

Done:

  CoreReleaseMemoryLock ();

  CoreReleaseGcdMemoryLock ();

  //
  // Update the map key finally
  //
  if (MapKey != NULL) {
    *MapKey = mMemoryMapKey;
  }

  *MemoryMapSize = BufferSize;

  return Status;
}


/**
  Internal function.  Used by the pool functions to allocate pages
  to back pool allocation requests.

  @param  PoolType               The type of memory for the new pool pages
  @param  NumberOfPages          No of pages to allocate
  @param  Alignment              Bits to align.

  @return The allocated memory, or NULL

**/
VOID *
CoreAllocatePoolPages (
  IN EFI_MEMORY_TYPE    PoolType,
  IN UINTN              NumberOfPages,
  IN UINTN              Alignment
  )
{
  UINT64            Start;

  //
  // Find the pages to convert
  //
  Start = FindFreePages (EFI_MAX_ADDRESS, NumberOfPages, PoolType, Alignment);

  //
  // Convert it to boot services data
  //
  if (Start == 0) {
    DEBUG ((DEBUG_ERROR | DEBUG_PAGE, "AllocatePoolPages: failed to allocate %d pages\n", NumberOfPages));
  } else {
    CoreConvertPages (Start, NumberOfPages, PoolType);
  }

  return (VOID *)(UINTN) Start;
}


/**
  Internal function.  Frees pool pages allocated via AllocatePoolPages ()

  @param  Memory                 The base address to free
  @param  NumberOfPages          The number of pages to free

**/
VOID
CoreFreePoolPages (
  IN EFI_PHYSICAL_ADDRESS   Memory,
  IN UINTN                  NumberOfPages
  )
{
  CoreConvertPages (Memory, NumberOfPages, EfiConventionalMemory);
}



/**
  Make sure the memory map is following all the construction rules,
  it is the last time to check memory map error before exit boot services.

  @param  MapKey                 Memory map key

  @retval EFI_INVALID_PARAMETER  Memory map not consistent with construction
                                 rules.
  @retval EFI_SUCCESS            Valid memory map.

**/
EFI_STATUS
CoreTerminateMemoryMap (
  IN UINTN          MapKey
  )
{
  EFI_STATUS        Status;
  LIST_ENTRY        *Link;
  MEMORY_MAP        *Entry;

  Status = EFI_SUCCESS;

  CoreAcquireMemoryLock ();

  if (MapKey == mMemoryMapKey) {

    //
    // Make sure the memory map is following all the construction rules
    // This is the last chance we will be able to display any messages on
    // the  console devices.
    //

    for (Link = gMemoryMap.ForwardLink; Link != &gMemoryMap; Link = Link->ForwardLink) {
      Entry = CR(Link, MEMORY_MAP, Link, MEMORY_MAP_SIGNATURE);
      if ((Entry->Attribute & EFI_MEMORY_RUNTIME) != 0) {
        if (Entry->Type == EfiACPIReclaimMemory || Entry->Type == EfiACPIMemoryNVS) {
          DEBUG((DEBUG_ERROR | DEBUG_PAGE, "ExitBootServices: ACPI memory entry has RUNTIME attribute set.\n"));
          Status =  EFI_INVALID_PARAMETER;
          goto Done;
        }
        if ((Entry->Start & (EFI_ACPI_RUNTIME_PAGE_ALLOCATION_ALIGNMENT - 1)) != 0) {
          DEBUG((DEBUG_ERROR | DEBUG_PAGE, "ExitBootServices: A RUNTIME memory entry is not on a proper alignment.\n"));
          Status =  EFI_INVALID_PARAMETER;
          goto Done;
        }
        if (((Entry->End + 1) & (EFI_ACPI_RUNTIME_PAGE_ALLOCATION_ALIGNMENT - 1)) != 0) {
          DEBUG((DEBUG_ERROR | DEBUG_PAGE, "ExitBootServices: A RUNTIME memory entry is not on a proper alignment.\n"));
          Status =  EFI_INVALID_PARAMETER;
          goto Done;
        }
      }
    }

    //
    // The map key they gave us matches what we expect. Fall through and
    // return success. In an ideal world we would clear out all of
    // EfiBootServicesCode and EfiBootServicesData. However this function
    // is not the last one called by ExitBootServices(), so we have to
    // preserve the memory contents.
    //
  } else {
    Status = EFI_INVALID_PARAMETER;
  }

Done:
  CoreReleaseMemoryLock ();

  return Status;
}