CreatePageTable.c

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#include <Library/CpuPageTableLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Base.h>
#include <Library/BaseMemoryLib.h>
#include <Library/DebugLib.h>
#include <Library/BaseLib.h>
 
UINTN
CreatePageTable (
  IN UINTN  Address,
  IN UINTN  Length
  )
{
  EFI_STATUS   Status;
  VOID         *PageTableBuffer;
  UINTN        PageTableBufferSize;
  UINTN        PageTable;
  PAGING_MODE  PagingMode;
  IA32_CR4     Cr4;
 
  IA32_MAP_ATTRIBUTE  MapAttribute;
  IA32_MAP_ATTRIBUTE  MapMask;
 
  MapAttribute.Uint64         = Address;
  MapAttribute.Bits.Present   = 1;
  MapAttribute.Bits.ReadWrite = 1;
  MapMask.Uint64              = MAX_UINT64;
 
  PageTable           = 0;
  PageTableBufferSize = 0;
 
  Cr4.UintN = AsmReadCr4 ();
 
  if (Cr4.Bits.LA57 == 1) {
    PagingMode = Paging5Level;
  } else {
    PagingMode = Paging4Level;
  }
 
  Status = PageTableMap (
             &PageTable,
             PagingMode,
             NULL,
             &PageTableBufferSize,
             Address,
             Length,
             &MapAttribute,
             &MapMask,
             NULL
             );
  ASSERT (Status == EFI_BUFFER_TOO_SMALL);
  DEBUG ((DEBUG_INFO, "AP Page Table Buffer Size = %x\n", PageTableBufferSize));
 
  PageTableBuffer = AllocateReservedPages (EFI_SIZE_TO_PAGES (PageTableBufferSize));
  ASSERT (PageTableBuffer != NULL);
  Status = PageTableMap (
             &PageTable,
             PagingMode,
             PageTableBuffer,
             &PageTableBufferSize,
             Address,
             Length,
             &MapAttribute,
             &MapMask,
             NULL
             );
  ASSERT_EFI_ERROR (Status);
  return PageTable;
}