CpuPageTable.c

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#include <Base.h>
#include <Uefi.h>
#include <Library/PeCoffGetEntryPointLib.h>
#include <Library/SerialPortLib.h>
#include <Library/SynchronizationLib.h>
#include <Library/PrintLib.h>
#include <Protocol/SmmBase2.h>
#include <Register/Intel/Cpuid.h>
#include <Register/Intel/Msr.h>
 
#include "CpuDxe.h"
#include "CpuPageTable.h"
 
#define IA32_PG_P       BIT0
#define IA32_PG_RW      BIT1
#define IA32_PG_U       BIT2
#define IA32_PG_WT      BIT3
#define IA32_PG_CD      BIT4
#define IA32_PG_A       BIT5
#define IA32_PG_D       BIT6
#define IA32_PG_PS      BIT7
#define IA32_PG_PAT_2M  BIT12
#define IA32_PG_PAT_4K  IA32_PG_PS
#define IA32_PG_PMNT    BIT62
#define IA32_PG_NX      BIT63
 
#define PAGE_ATTRIBUTE_BITS  (IA32_PG_D | IA32_PG_A | IA32_PG_U | IA32_PG_RW | IA32_PG_P)
//
// Bits 1, 2, 5, 6 are reserved in the IA32 PAE PDPTE
// X64 PAE PDPTE does not have such restriction
//
#define IA32_PAE_PDPTE_ATTRIBUTE_BITS  (IA32_PG_P)
 
#define PAGE_PROGATE_BITS  (IA32_PG_NX | PAGE_ATTRIBUTE_BITS)
 
#define PAGING_4K_MASK  0xFFF
#define PAGING_2M_MASK  0x1FFFFF
#define PAGING_1G_MASK  0x3FFFFFFF
 
#define PAGING_PAE_INDEX_MASK  0x1FF
 
#define PAGING_4K_ADDRESS_MASK_64  0x000FFFFFFFFFF000ull
#define PAGING_2M_ADDRESS_MASK_64  0x000FFFFFFFE00000ull
#define PAGING_1G_ADDRESS_MASK_64  0x000FFFFFC0000000ull
 
#define MAX_PF_ENTRY_COUNT        10
#define MAX_DEBUG_MESSAGE_LENGTH  0x100
#define IA32_PF_EC_ID             BIT4
 
typedef enum {
  PageNone,
  Page4K,
  Page2M,
  Page1G,
} PAGE_ATTRIBUTE;
 
typedef struct {
  PAGE_ATTRIBUTE    Attribute;
  UINT64            Length;
  UINT64            AddressMask;
} PAGE_ATTRIBUTE_TABLE;
 
typedef enum {
  PageActionAssign,
  PageActionSet,
  PageActionClear,
} PAGE_ACTION;
 
PAGE_ATTRIBUTE_TABLE  mPageAttributeTable[] = {
  { Page4K, SIZE_4KB, PAGING_4K_ADDRESS_MASK_64 },
  { Page2M, SIZE_2MB, PAGING_2M_ADDRESS_MASK_64 },
  { Page1G, SIZE_1GB, PAGING_1G_ADDRESS_MASK_64 },
};
 
PAGE_TABLE_POOL                *mPageTablePool    = NULL;
BOOLEAN                        mPageTablePoolLock = FALSE;
PAGE_TABLE_LIB_PAGING_CONTEXT  mPagingContext;
EFI_SMM_BASE2_PROTOCOL         *mSmmBase2 = NULL;
 
//
// Record the page fault exception count for one instruction execution.
//
UINTN  *mPFEntryCount;
UINT64                    *(*mLastPFEntryPointer)[MAX_PF_ENTRY_COUNT];
 
BOOLEAN
IsInSmm (
  VOID
  )
{
  BOOLEAN  InSmm;
 
  InSmm = FALSE;
  if (mSmmBase2 == NULL) {
    gBS->LocateProtocol (&gEfiSmmBase2ProtocolGuid, NULL, (VOID **)&mSmmBase2);
  }
 
  if (mSmmBase2 != NULL) {
    mSmmBase2->InSmm (mSmmBase2, &InSmm);
  }
 
  //
  // mSmmBase2->InSmm() can only detect if the caller is running in SMRAM
  // or from SMM driver. It cannot tell if the caller is running in SMM mode.
  // Check page table base address to guarantee that because SMM mode willl
  // load its own page table.
  //
  return (InSmm &&
          mPagingContext.ContextData.X64.PageTableBase != (UINT64)AsmReadCr3 ());
}
 
VOID
GetCurrentPagingContext (
  IN OUT PAGE_TABLE_LIB_PAGING_CONTEXT  *PagingContext
  )
{
  UINT32                      RegEax;
  CPUID_EXTENDED_CPU_SIG_EDX  RegEdx;
  MSR_IA32_EFER_REGISTER      MsrEfer;
  IA32_CR4                    Cr4;
  IA32_CR0                    Cr0;
  UINT32                      *Attributes;
  UINTN                       *PageTableBase;
 
  //
  // Don't retrieve current paging context from processor if in SMM mode.
  //
  if (!IsInSmm ()) {
    ZeroMem (&mPagingContext, sizeof (mPagingContext));
    if (sizeof (UINTN) == sizeof (UINT64)) {
      mPagingContext.MachineType = IMAGE_FILE_MACHINE_X64;
    } else {
      mPagingContext.MachineType = IMAGE_FILE_MACHINE_I386;
    }
 
    GetPagingDetails (&mPagingContext.ContextData, &PageTableBase, &Attributes);
 
    Cr0.UintN = AsmReadCr0 ();
    Cr4.UintN = AsmReadCr4 ();
 
    if (Cr0.Bits.PG != 0) {
      *PageTableBase = (AsmReadCr3 () & PAGING_4K_ADDRESS_MASK_64);
    } else {
      *PageTableBase = 0;
    }
 
    if (Cr0.Bits.WP  != 0) {
      *Attributes |= PAGE_TABLE_LIB_PAGING_CONTEXT_IA32_X64_ATTRIBUTES_WP_ENABLE;
    }
 
    if (Cr4.Bits.PSE != 0) {
      *Attributes |= PAGE_TABLE_LIB_PAGING_CONTEXT_IA32_X64_ATTRIBUTES_PSE;
    }
 
    if (Cr4.Bits.PAE != 0) {
      *Attributes |= PAGE_TABLE_LIB_PAGING_CONTEXT_IA32_X64_ATTRIBUTES_PAE;
    }
 
    if (Cr4.Bits.LA57 != 0) {
      *Attributes |= PAGE_TABLE_LIB_PAGING_CONTEXT_IA32_X64_ATTRIBUTES_5_LEVEL;
    }
 
    AsmCpuid (CPUID_EXTENDED_FUNCTION, &RegEax, NULL, NULL, NULL);
    if (RegEax >= CPUID_EXTENDED_CPU_SIG) {
      AsmCpuid (CPUID_EXTENDED_CPU_SIG, NULL, NULL, NULL, &RegEdx.Uint32);
 
      if (RegEdx.Bits.NX != 0) {
        // XD supported
        MsrEfer.Uint64 = AsmReadMsr64 (MSR_CORE_IA32_EFER);
        if (MsrEfer.Bits.NXE != 0) {
          // XD activated
          *Attributes |= PAGE_TABLE_LIB_PAGING_CONTEXT_IA32_X64_ATTRIBUTES_XD_ACTIVATED;
        }
      }
 
      if (RegEdx.Bits.Page1GB != 0) {
        *Attributes |= PAGE_TABLE_LIB_PAGING_CONTEXT_IA32_X64_ATTRIBUTES_PAGE_1G_SUPPORT;
      }
    }
  }
 
  //
  // This can avoid getting SMM paging context if in SMM mode. We cannot assume
  // SMM mode shares the same paging context as DXE.
  //
  CopyMem (PagingContext, &mPagingContext, sizeof (mPagingContext));
}
 
UINTN
PageAttributeToLength (
  IN PAGE_ATTRIBUTE  PageAttribute
  )
{
  UINTN  Index;
 
  for (Index = 0; Index < sizeof (mPageAttributeTable)/sizeof (mPageAttributeTable[0]); Index++) {
    if (PageAttribute == mPageAttributeTable[Index].Attribute) {
      return (UINTN)mPageAttributeTable[Index].Length;
    }
  }
 
  return 0;
}
 
UINTN
PageAttributeToMask (
  IN PAGE_ATTRIBUTE  PageAttribute
  )
{
  UINTN  Index;
 
  for (Index = 0; Index < sizeof (mPageAttributeTable)/sizeof (mPageAttributeTable[0]); Index++) {
    if (PageAttribute == mPageAttributeTable[Index].Attribute) {
      return (UINTN)mPageAttributeTable[Index].AddressMask;
    }
  }
 
  return 0;
}
 
VOID *
GetPageTableEntry (
  IN  PAGE_TABLE_LIB_PAGING_CONTEXT  *PagingContext,
  IN  PHYSICAL_ADDRESS               Address,
  OUT PAGE_ATTRIBUTE                 *PageAttribute
  )
{
  UINTN   Index1;
  UINTN   Index2;
  UINTN   Index3;
  UINTN   Index4;
  UINTN   Index5;
  UINT64  *L1PageTable;
  UINT64  *L2PageTable;
  UINT64  *L3PageTable;
  UINT64  *L4PageTable;
  UINT64  *L5PageTable;
  UINT64  AddressEncMask;
 
  ASSERT (PagingContext != NULL);
 
  Index5 = ((UINTN)RShiftU64 (Address, 48)) & PAGING_PAE_INDEX_MASK;
  Index4 = ((UINTN)RShiftU64 (Address, 39)) & PAGING_PAE_INDEX_MASK;
  Index3 = ((UINTN)Address >> 30) & PAGING_PAE_INDEX_MASK;
  Index2 = ((UINTN)Address >> 21) & PAGING_PAE_INDEX_MASK;
  Index1 = ((UINTN)Address >> 12) & PAGING_PAE_INDEX_MASK;
 
  // Make sure AddressEncMask is contained to smallest supported address field.
  //
  AddressEncMask = PcdGet64 (PcdPteMemoryEncryptionAddressOrMask) & PAGING_1G_ADDRESS_MASK_64;
  if (AddressEncMask == 0) {
    AddressEncMask = PcdGet64 (PcdTdxSharedBitMask) & PAGING_1G_ADDRESS_MASK_64;
  }
 
  if (PagingContext->MachineType == IMAGE_FILE_MACHINE_X64) {
    if ((PagingContext->ContextData.X64.Attributes & PAGE_TABLE_LIB_PAGING_CONTEXT_IA32_X64_ATTRIBUTES_5_LEVEL) != 0) {
      L5PageTable = (UINT64 *)(UINTN)PagingContext->ContextData.X64.PageTableBase;
      if (L5PageTable[Index5] == 0) {
        *PageAttribute = PageNone;
        return NULL;
      }
 
      L4PageTable = (UINT64 *)(UINTN)(L5PageTable[Index5] & ~AddressEncMask & PAGING_4K_ADDRESS_MASK_64);
    } else {
      L4PageTable = (UINT64 *)(UINTN)PagingContext->ContextData.X64.PageTableBase;
    }
 
    if (L4PageTable[Index4] == 0) {
      *PageAttribute = PageNone;
      return NULL;
    }
 
    L3PageTable = (UINT64 *)(UINTN)(L4PageTable[Index4] & ~AddressEncMask & PAGING_4K_ADDRESS_MASK_64);
  } else {
    ASSERT ((PagingContext->ContextData.Ia32.Attributes & PAGE_TABLE_LIB_PAGING_CONTEXT_IA32_X64_ATTRIBUTES_PAE) != 0);
    L3PageTable = (UINT64 *)(UINTN)PagingContext->ContextData.Ia32.PageTableBase;
  }
 
  if (L3PageTable[Index3] == 0) {
    *PageAttribute = PageNone;
    return NULL;
  }
 
  if ((L3PageTable[Index3] & IA32_PG_PS) != 0) {
    // 1G
    *PageAttribute = Page1G;
    return &L3PageTable[Index3];
  }
 
  L2PageTable = (UINT64 *)(UINTN)(L3PageTable[Index3] & ~AddressEncMask & PAGING_4K_ADDRESS_MASK_64);
  if (L2PageTable[Index2] == 0) {
    *PageAttribute = PageNone;
    return NULL;
  }
 
  if ((L2PageTable[Index2] & IA32_PG_PS) != 0) {
    // 2M
    *PageAttribute = Page2M;
    return &L2PageTable[Index2];
  }
 
  // 4k
  L1PageTable = (UINT64 *)(UINTN)(L2PageTable[Index2] & ~AddressEncMask & PAGING_4K_ADDRESS_MASK_64);
  if ((L1PageTable[Index1] == 0) && (Address != 0)) {
    *PageAttribute = PageNone;
    return NULL;
  }
 
  *PageAttribute = Page4K;
  return &L1PageTable[Index1];
}
 
UINT64
GetAttributesFromPageEntry (
  IN  UINT64  *PageEntry
  )
{
  UINT64  Attributes;
 
  Attributes = 0;
  if ((*PageEntry & IA32_PG_P) == 0) {
    Attributes |= EFI_MEMORY_RP;
  }
 
  if ((*PageEntry & IA32_PG_RW) == 0) {
    Attributes |= EFI_MEMORY_RO;
  }
 
  if ((*PageEntry & IA32_PG_NX) != 0) {
    Attributes |= EFI_MEMORY_XP;
  }
 
  return Attributes;
}
 
VOID
ConvertPageEntryAttribute (
  IN  PAGE_TABLE_LIB_PAGING_CONTEXT  *PagingContext,
  IN  UINT64                         *PageEntry,
  IN  UINT64                         Attributes,
  IN  PAGE_ACTION                    PageAction,
  OUT BOOLEAN                        *IsModified
  )
{
  UINT64  CurrentPageEntry;
  UINT64  NewPageEntry;
  UINT32  *PageAttributes;
 
  CurrentPageEntry = *PageEntry;
  NewPageEntry     = CurrentPageEntry;
  if ((Attributes & EFI_MEMORY_RP) != 0) {
    switch (PageAction) {
      case PageActionAssign:
      case PageActionSet:
        NewPageEntry &= ~(UINT64)IA32_PG_P;
        break;
      case PageActionClear:
        NewPageEntry |= IA32_PG_P;
        break;
    }
  } else {
    switch (PageAction) {
      case PageActionAssign:
        NewPageEntry |= IA32_PG_P;
        break;
      case PageActionSet:
      case PageActionClear:
        break;
    }
  }
 
  if ((Attributes & EFI_MEMORY_RO) != 0) {
    switch (PageAction) {
      case PageActionAssign:
      case PageActionSet:
        NewPageEntry &= ~(UINT64)IA32_PG_RW;
        break;
      case PageActionClear:
        NewPageEntry |= IA32_PG_RW;
        break;
    }
  } else {
    switch (PageAction) {
      case PageActionAssign:
        NewPageEntry |= IA32_PG_RW;
        break;
      case PageActionSet:
      case PageActionClear:
        break;
    }
  }
 
  GetPagingDetails (&PagingContext->ContextData, NULL, &PageAttributes);
 
  if ((*PageAttributes & PAGE_TABLE_LIB_PAGING_CONTEXT_IA32_X64_ATTRIBUTES_XD_ACTIVATED) != 0) {
    if ((Attributes & EFI_MEMORY_XP) != 0) {
      switch (PageAction) {
        case PageActionAssign:
        case PageActionSet:
          NewPageEntry |= IA32_PG_NX;
          break;
        case PageActionClear:
          NewPageEntry &= ~IA32_PG_NX;
          break;
      }
    } else {
      switch (PageAction) {
        case PageActionAssign:
          NewPageEntry &= ~IA32_PG_NX;
          break;
        case PageActionSet:
        case PageActionClear:
          break;
      }
    }
  }
 
  *PageEntry = NewPageEntry;
  if (CurrentPageEntry != NewPageEntry) {
    *IsModified = TRUE;
    DEBUG ((DEBUG_VERBOSE, "ConvertPageEntryAttribute 0x%lx", CurrentPageEntry));
    DEBUG ((DEBUG_VERBOSE, "->0x%lx\n", NewPageEntry));
  } else {
    *IsModified = FALSE;
  }
}
 
PAGE_ATTRIBUTE
NeedSplitPage (
  IN  PHYSICAL_ADDRESS  BaseAddress,
  IN  UINT64            Length,
  IN  UINT64            *PageEntry,
  IN  PAGE_ATTRIBUTE    PageAttribute
  )
{
  UINT64  PageEntryLength;
 
  PageEntryLength = PageAttributeToLength (PageAttribute);
 
  if (((BaseAddress & (PageEntryLength - 1)) == 0) && (Length >= PageEntryLength)) {
    return PageNone;
  }
 
  if (((BaseAddress & PAGING_2M_MASK) != 0) || (Length < SIZE_2MB)) {
    return Page4K;
  }
 
  return Page2M;
}
 
RETURN_STATUS
SplitPage (
  IN  UINT64                         *PageEntry,
  IN  PAGE_ATTRIBUTE                 PageAttribute,
  IN  PAGE_ATTRIBUTE                 SplitAttribute,
  IN  PAGE_TABLE_LIB_ALLOCATE_PAGES  AllocatePagesFunc
  )
{
  UINT64  BaseAddress;
  UINT64  *NewPageEntry;
  UINTN   Index;
  UINT64  AddressEncMask;
 
  ASSERT (PageAttribute == Page2M || PageAttribute == Page1G);
 
  ASSERT (AllocatePagesFunc != NULL);
 
  // Make sure AddressEncMask is contained to smallest supported address field.
  //
  AddressEncMask = PcdGet64 (PcdPteMemoryEncryptionAddressOrMask) & PAGING_1G_ADDRESS_MASK_64;
 
  if (PageAttribute == Page2M) {
    //
    // Split 2M to 4K
    //
    ASSERT (SplitAttribute == Page4K);
    if (SplitAttribute == Page4K) {
      NewPageEntry = AllocatePagesFunc (1);
      DEBUG ((DEBUG_VERBOSE, "Split - 0x%x\n", NewPageEntry));
      if (NewPageEntry == NULL) {
        return RETURN_OUT_OF_RESOURCES;
      }
 
      BaseAddress = *PageEntry & ~AddressEncMask & PAGING_2M_ADDRESS_MASK_64;
      for (Index = 0; Index < SIZE_4KB / sizeof (UINT64); Index++) {
        NewPageEntry[Index] = (BaseAddress + SIZE_4KB * Index) | AddressEncMask | ((*PageEntry) & PAGE_PROGATE_BITS);
      }
 
      (*PageEntry) = (UINT64)(UINTN)NewPageEntry | AddressEncMask | ((*PageEntry) & PAGE_ATTRIBUTE_BITS);
      return RETURN_SUCCESS;
    } else {
      return RETURN_UNSUPPORTED;
    }
  } else if (PageAttribute == Page1G) {
    //
    // Split 1G to 2M
    // No need support 1G->4K directly, we should use 1G->2M, then 2M->4K to get more compact page table.
    //
    ASSERT (SplitAttribute == Page2M || SplitAttribute == Page4K);
    if (((SplitAttribute == Page2M) || (SplitAttribute == Page4K))) {
      NewPageEntry = AllocatePagesFunc (1);
      DEBUG ((DEBUG_VERBOSE, "Split - 0x%x\n", NewPageEntry));
      if (NewPageEntry == NULL) {
        return RETURN_OUT_OF_RESOURCES;
      }
 
      BaseAddress = *PageEntry & ~AddressEncMask  & PAGING_1G_ADDRESS_MASK_64;
      for (Index = 0; Index < SIZE_4KB / sizeof (UINT64); Index++) {
        NewPageEntry[Index] = (BaseAddress + SIZE_2MB * Index) | AddressEncMask | IA32_PG_PS | ((*PageEntry) & PAGE_PROGATE_BITS);
      }
 
      (*PageEntry) = (UINT64)(UINTN)NewPageEntry | AddressEncMask | ((*PageEntry) & PAGE_ATTRIBUTE_BITS);
      return RETURN_SUCCESS;
    } else {
      return RETURN_UNSUPPORTED;
    }
  } else {
    return RETURN_UNSUPPORTED;
  }
}
 
BOOLEAN
IsReadOnlyPageWriteProtected (
  VOID
  )
{
  IA32_CR0  Cr0;
 
  //
  // To avoid unforseen consequences, don't touch paging settings in SMM mode
  // in this driver.
  //
  if (!IsInSmm ()) {
    Cr0.UintN = AsmReadCr0 ();
    return (BOOLEAN)(Cr0.Bits.WP != 0);
  }
 
  return FALSE;
}
 
VOID
DisableReadOnlyPageWriteProtect (
  VOID
  )
{
  IA32_CR0  Cr0;
 
  //
  // To avoid unforseen consequences, don't touch paging settings in SMM mode
  // in this driver.
  //
  if (!IsInSmm ()) {
    Cr0.UintN   = AsmReadCr0 ();
    Cr0.Bits.WP = 0;
    AsmWriteCr0 (Cr0.UintN);
  }
}
 
VOID
EnableReadOnlyPageWriteProtect (
  VOID
  )
{
  IA32_CR0  Cr0;
 
  //
  // To avoid unforseen consequences, don't touch paging settings in SMM mode
  // in this driver.
  //
  if (!IsInSmm ()) {
    Cr0.UintN   = AsmReadCr0 ();
    Cr0.Bits.WP = 1;
    AsmWriteCr0 (Cr0.UintN);
  }
}
 
RETURN_STATUS
ConvertMemoryPageAttributes (
  IN  PAGE_TABLE_LIB_PAGING_CONTEXT  *PagingContext OPTIONAL,
  IN  PHYSICAL_ADDRESS               BaseAddress,
  IN  UINT64                         Length,
  IN  UINT64                         Attributes,
  IN  PAGE_ACTION                    PageAction,
  IN  PAGE_TABLE_LIB_ALLOCATE_PAGES  AllocatePagesFunc OPTIONAL,
  OUT BOOLEAN                        *IsSplitted   OPTIONAL,
  OUT BOOLEAN                        *IsModified   OPTIONAL
  )
{
  PAGE_TABLE_LIB_PAGING_CONTEXT  CurrentPagingContext;
  UINT64                         *PageEntry;
  PAGE_ATTRIBUTE                 PageAttribute;
  UINTN                          PageEntryLength;
  PAGE_ATTRIBUTE                 SplitAttribute;
  RETURN_STATUS                  Status;
  BOOLEAN                        IsEntryModified;
  BOOLEAN                        IsWpEnabled;
 
  if ((BaseAddress & (SIZE_4KB - 1)) != 0) {
    DEBUG ((DEBUG_ERROR, "BaseAddress(0x%lx) is not aligned!\n", BaseAddress));
    return EFI_UNSUPPORTED;
  }
 
  if ((Length & (SIZE_4KB - 1)) != 0) {
    DEBUG ((DEBUG_ERROR, "Length(0x%lx) is not aligned!\n", Length));
    return EFI_UNSUPPORTED;
  }
 
  if (Length == 0) {
    DEBUG ((DEBUG_ERROR, "Length is 0!\n"));
    return RETURN_INVALID_PARAMETER;
  }
 
  if ((Attributes & ~EFI_MEMORY_ATTRIBUTE_MASK) != 0) {
    DEBUG ((DEBUG_ERROR, "Attributes(0x%lx) has unsupported bit\n", Attributes));
    return EFI_UNSUPPORTED;
  }
 
  if (PagingContext == NULL) {
    GetCurrentPagingContext (&CurrentPagingContext);
  } else {
    CopyMem (&CurrentPagingContext, PagingContext, sizeof (CurrentPagingContext));
  }
 
  switch (CurrentPagingContext.MachineType) {
    case IMAGE_FILE_MACHINE_I386:
      if (CurrentPagingContext.ContextData.Ia32.PageTableBase == 0) {
        if (Attributes == 0) {
          return EFI_SUCCESS;
        } else {
          DEBUG ((DEBUG_ERROR, "PageTable is 0!\n"));
          return EFI_UNSUPPORTED;
        }
      }
 
      if ((CurrentPagingContext.ContextData.Ia32.Attributes & PAGE_TABLE_LIB_PAGING_CONTEXT_IA32_X64_ATTRIBUTES_PAE) == 0) {
        DEBUG ((DEBUG_ERROR, "Non-PAE Paging!\n"));
        return EFI_UNSUPPORTED;
      }
 
      if ((BaseAddress + Length) > BASE_4GB) {
        DEBUG ((DEBUG_ERROR, "Beyond 4GB memory in 32-bit mode!\n"));
        return EFI_UNSUPPORTED;
      }
 
      break;
    case IMAGE_FILE_MACHINE_X64:
      ASSERT (CurrentPagingContext.ContextData.X64.PageTableBase != 0);
      break;
    default:
      ASSERT (FALSE);
      return EFI_UNSUPPORTED;
      break;
  }
 
  //  DEBUG ((DEBUG_ERROR, "ConvertMemoryPageAttributes(%x) - %016lx, %016lx, %02lx\n", IsSet, BaseAddress, Length, Attributes));
 
  if (IsSplitted != NULL) {
    *IsSplitted = FALSE;
  }
 
  if (IsModified != NULL) {
    *IsModified = FALSE;
  }
 
  if (AllocatePagesFunc == NULL) {
    AllocatePagesFunc = AllocatePageTableMemory;
  }
 
  //
  // Make sure that the page table is changeable.
  //
  IsWpEnabled = IsReadOnlyPageWriteProtected ();
  if (IsWpEnabled) {
    DisableReadOnlyPageWriteProtect ();
  }
 
  //
  // Below logic is to check 2M/4K page to make sure we do not waste memory.
  //
  Status = EFI_SUCCESS;
  while (Length != 0) {
    PageEntry = GetPageTableEntry (&CurrentPagingContext, BaseAddress, &PageAttribute);
    if (PageEntry == NULL) {
      Status = RETURN_UNSUPPORTED;
      goto Done;
    }
 
    PageEntryLength = PageAttributeToLength (PageAttribute);
    SplitAttribute  = NeedSplitPage (BaseAddress, Length, PageEntry, PageAttribute);
    if (SplitAttribute == PageNone) {
      ConvertPageEntryAttribute (&CurrentPagingContext, PageEntry, Attributes, PageAction, &IsEntryModified);
      if (IsEntryModified) {
        if (IsModified != NULL) {
          *IsModified = TRUE;
        }
      }
 
      //
      // Convert success, move to next
      //
      BaseAddress += PageEntryLength;
      Length      -= PageEntryLength;
    } else {
      if (AllocatePagesFunc == NULL) {
        Status = RETURN_UNSUPPORTED;
        goto Done;
      }
 
      Status = SplitPage (PageEntry, PageAttribute, SplitAttribute, AllocatePagesFunc);
      if (RETURN_ERROR (Status)) {
        Status = RETURN_UNSUPPORTED;
        goto Done;
      }
 
      if (IsSplitted != NULL) {
        *IsSplitted = TRUE;
      }
 
      if (IsModified != NULL) {
        *IsModified = TRUE;
      }
 
      //
      // Just split current page
      // Convert success in next around
      //
    }
  }
 
Done:
  //
  // Restore page table write protection, if any.
  //
  if (IsWpEnabled) {
    EnableReadOnlyPageWriteProtect ();
  }
 
  return Status;
}
 
RETURN_STATUS
EFIAPI
AssignMemoryPageAttributes (
  IN  PAGE_TABLE_LIB_PAGING_CONTEXT  *PagingContext OPTIONAL,
  IN  PHYSICAL_ADDRESS               BaseAddress,
  IN  UINT64                         Length,
  IN  UINT64                         Attributes,
  IN  PAGE_TABLE_LIB_ALLOCATE_PAGES  AllocatePagesFunc OPTIONAL
  )
{
  RETURN_STATUS  Status;
  BOOLEAN        IsModified;
  BOOLEAN        IsSplitted;
 
  //  DEBUG((DEBUG_INFO, "AssignMemoryPageAttributes: 0x%lx - 0x%lx (0x%lx)\n", BaseAddress, Length, Attributes));
  Status = ConvertMemoryPageAttributes (PagingContext, BaseAddress, Length, Attributes, PageActionAssign, AllocatePagesFunc, &IsSplitted, &IsModified);
  if (!EFI_ERROR (Status)) {
    if ((PagingContext == NULL) && IsModified) {
      //
      // Flush TLB as last step.
      //
      // Note: Since APs will always init CR3 register in HLT loop mode or do
      // TLB flush in MWAIT loop mode, there's no need to flush TLB for them
      // here.
      //
      CpuFlushTlb ();
    }
  }
 
  return Status;
}
 
BOOLEAN
IsExecuteDisableEnabled (
  VOID
  )
{
  MSR_CORE_IA32_EFER_REGISTER  MsrEfer;
 
  MsrEfer.Uint64 = AsmReadMsr64 (MSR_IA32_EFER);
  return (MsrEfer.Bits.NXE == 1);
}
 
VOID
RefreshGcdMemoryAttributesFromPaging (
  VOID
  )
{
  EFI_STATUS                       Status;
  UINTN                            NumberOfDescriptors;
  EFI_GCD_MEMORY_SPACE_DESCRIPTOR  *MemorySpaceMap;
  PAGE_TABLE_LIB_PAGING_CONTEXT    PagingContext;
  PAGE_ATTRIBUTE                   PageAttribute;
  UINT64                           *PageEntry;
  UINT64                           PageLength;
  UINT64                           MemorySpaceLength;
  UINT64                           Length;
  UINT64                           BaseAddress;
  UINT64                           PageStartAddress;
  UINT64                           Attributes;
  UINT64                           Capabilities;
  UINT64                           NewAttributes;
  UINTN                            Index;
 
  //
  // Assuming that memory space map returned is sorted already; otherwise sort
  // them in the order of lowest address to highest address.
  //
  Status = gDS->GetMemorySpaceMap (&NumberOfDescriptors, &MemorySpaceMap);
  ASSERT_EFI_ERROR (Status);
 
  GetCurrentPagingContext (&PagingContext);
 
  Attributes    = 0;
  NewAttributes = 0;
  BaseAddress   = 0;
  PageLength    = 0;
 
  if (IsExecuteDisableEnabled ()) {
    Capabilities = EFI_MEMORY_RO | EFI_MEMORY_RP | EFI_MEMORY_XP;
  } else {
    Capabilities = EFI_MEMORY_RO | EFI_MEMORY_RP;
  }
 
  for (Index = 0; Index < NumberOfDescriptors; Index++) {
    if (MemorySpaceMap[Index].GcdMemoryType == EfiGcdMemoryTypeNonExistent) {
      continue;
    }
 
    //
    // Sync the actual paging related capabilities back to GCD service first.
    // As a side effect (good one), this can also help to avoid unnecessary
    // memory map entries due to the different capabilities of the same type
    // memory, such as multiple RT_CODE and RT_DATA entries in memory map,
    // which could cause boot failure of some old Linux distro (before v4.3).
    //
    Status = gDS->SetMemorySpaceCapabilities (
                    MemorySpaceMap[Index].BaseAddress,
                    MemorySpaceMap[Index].Length,
                    MemorySpaceMap[Index].Capabilities | Capabilities
                    );
    if (EFI_ERROR (Status)) {
      //
      // If we cannot update the capabilities, we cannot update its
      // attributes either. So just simply skip current block of memory.
      //
      DEBUG ((
        DEBUG_WARN,
        "Failed to update capability: [%lu] %016lx - %016lx (%016lx -> %016lx)\r\n",
        (UINT64)Index,
        MemorySpaceMap[Index].BaseAddress,
        MemorySpaceMap[Index].BaseAddress + MemorySpaceMap[Index].Length - 1,
        MemorySpaceMap[Index].Capabilities,
        MemorySpaceMap[Index].Capabilities | Capabilities
        ));
      continue;
    }
 
    if (MemorySpaceMap[Index].BaseAddress >= (BaseAddress + PageLength)) {
      //
      // Current memory space starts at a new page. Resetting PageLength will
      // trigger a retrieval of page attributes at new address.
      //
      PageLength = 0;
    } else {
      //
      // In case current memory space is not adjacent to last one
      //
      PageLength -= (MemorySpaceMap[Index].BaseAddress - BaseAddress);
    }
 
    //
    // Sync actual page attributes to GCD
    //
    BaseAddress       = MemorySpaceMap[Index].BaseAddress;
    MemorySpaceLength = MemorySpaceMap[Index].Length;
    while (MemorySpaceLength > 0) {
      if (PageLength == 0) {
        PageEntry = GetPageTableEntry (&PagingContext, BaseAddress, &PageAttribute);
        if (PageEntry == NULL) {
          break;
        }
 
        //
        // Note current memory space might start in the middle of a page
        //
        PageStartAddress = (*PageEntry) & (UINT64)PageAttributeToMask (PageAttribute);
        PageLength       = PageAttributeToLength (PageAttribute) - (BaseAddress - PageStartAddress);
        Attributes       = GetAttributesFromPageEntry (PageEntry);
      }
 
      Length = MIN (PageLength, MemorySpaceLength);
      if (Attributes != (MemorySpaceMap[Index].Attributes &
                         EFI_MEMORY_ATTRIBUTE_MASK))
      {
        NewAttributes = (MemorySpaceMap[Index].Attributes &
                         ~EFI_MEMORY_ATTRIBUTE_MASK) | Attributes;
        Status = gDS->SetMemorySpaceAttributes (
                        BaseAddress,
                        Length,
                        NewAttributes
                        );
        ASSERT_EFI_ERROR (Status);
        DEBUG ((
          DEBUG_VERBOSE,
          "Updated memory space attribute: [%lu] %016lx - %016lx (%016lx -> %016lx)\r\n",
          (UINT64)Index,
          BaseAddress,
          BaseAddress + Length - 1,
          MemorySpaceMap[Index].Attributes,
          NewAttributes
          ));
      }
 
      PageLength        -= Length;
      MemorySpaceLength -= Length;
      BaseAddress       += Length;
    }
  }
 
  FreePool (MemorySpaceMap);
}
 
BOOLEAN
InitializePageTablePool (
  IN  UINTN  PoolPages
  )
{
  VOID     *Buffer;
  BOOLEAN  IsModified;
 
  //
  // Do not allow re-entrance.
  //
  if (mPageTablePoolLock) {
    return FALSE;
  }
 
  mPageTablePoolLock = TRUE;
  IsModified         = FALSE;
 
  //
  // Always reserve at least PAGE_TABLE_POOL_UNIT_PAGES, including one page for
  // header.
  //
  PoolPages += 1;   // Add one page for header.
  PoolPages  = ((PoolPages - 1) / PAGE_TABLE_POOL_UNIT_PAGES + 1) *
               PAGE_TABLE_POOL_UNIT_PAGES;
  Buffer = AllocateAlignedPages (PoolPages, PAGE_TABLE_POOL_ALIGNMENT);
  if (Buffer == NULL) {
    DEBUG ((DEBUG_ERROR, "ERROR: Out of aligned pages\r\n"));
    goto Done;
  }
 
  DEBUG ((
    DEBUG_INFO,
    "Paging: added %lu pages to page table pool\r\n",
    (UINT64)PoolPages
    ));
 
  //
  // Link all pools into a list for easier track later.
  //
  if (mPageTablePool == NULL) {
    mPageTablePool           = Buffer;
    mPageTablePool->NextPool = mPageTablePool;
  } else {
    ((PAGE_TABLE_POOL *)Buffer)->NextPool = mPageTablePool->NextPool;
    mPageTablePool->NextPool              = Buffer;
    mPageTablePool                        = Buffer;
  }
 
  //
  // Reserve one page for pool header.
  //
  mPageTablePool->FreePages = PoolPages - 1;
  mPageTablePool->Offset    = EFI_PAGES_TO_SIZE (1);
 
  //
  // Mark the whole pool pages as read-only.
  //
  ConvertMemoryPageAttributes (
    NULL,
    (PHYSICAL_ADDRESS)(UINTN)Buffer,
    EFI_PAGES_TO_SIZE (PoolPages),
    EFI_MEMORY_RO,
    PageActionSet,
    AllocatePageTableMemory,
    NULL,
    &IsModified
    );
  ASSERT (IsModified == TRUE);
 
Done:
  mPageTablePoolLock = FALSE;
  return IsModified;
}
 
VOID *
EFIAPI
AllocatePageTableMemory (
  IN UINTN  Pages
  )
{
  VOID  *Buffer;
 
  if (Pages == 0) {
    return NULL;
  }
 
  //
  // Renew the pool if necessary.
  //
  if ((mPageTablePool == NULL) ||
      (Pages > mPageTablePool->FreePages))
  {
    if (!InitializePageTablePool (Pages)) {
      return NULL;
    }
  }
 
  Buffer = (UINT8 *)mPageTablePool + mPageTablePool->Offset;
 
  mPageTablePool->Offset    += EFI_PAGES_TO_SIZE (Pages);
  mPageTablePool->FreePages -= Pages;
 
  return Buffer;
}
 
VOID
EFIAPI
DebugExceptionHandler (
  IN EFI_EXCEPTION_TYPE  ExceptionType,
  IN EFI_SYSTEM_CONTEXT  SystemContext
  )
{
  UINTN    CpuIndex;
  UINTN    PFEntry;
  BOOLEAN  IsWpEnabled;
 
  MpInitLibWhoAmI (&CpuIndex);
 
  //
  // Clear last PF entries
  //
  IsWpEnabled = IsReadOnlyPageWriteProtected ();
  if (IsWpEnabled) {
    DisableReadOnlyPageWriteProtect ();
  }
 
  for (PFEntry = 0; PFEntry < mPFEntryCount[CpuIndex]; PFEntry++) {
    if (mLastPFEntryPointer[CpuIndex][PFEntry] != NULL) {
      *mLastPFEntryPointer[CpuIndex][PFEntry] &= ~(UINT64)IA32_PG_P;
    }
  }
 
  if (IsWpEnabled) {
    EnableReadOnlyPageWriteProtect ();
  }
 
  //
  // Reset page fault exception count for next page fault.
  //
  mPFEntryCount[CpuIndex] = 0;
 
  //
  // Flush TLB
  //
  CpuFlushTlb ();
 
  //
  // Clear TF in EFLAGS
  //
  if (mPagingContext.MachineType == IMAGE_FILE_MACHINE_I386) {
    SystemContext.SystemContextIa32->Eflags &= (UINT32) ~BIT8;
  } else {
    SystemContext.SystemContextX64->Rflags &= (UINT64) ~BIT8;
  }
}
 
VOID
EFIAPI
PageFaultExceptionHandler (
  IN EFI_EXCEPTION_TYPE  ExceptionType,
  IN EFI_SYSTEM_CONTEXT  SystemContext
  )
{
  EFI_STATUS                     Status;
  UINT64                         PFAddress;
  PAGE_TABLE_LIB_PAGING_CONTEXT  PagingContext;
  PAGE_ATTRIBUTE                 PageAttribute;
  UINT64                         Attributes;
  UINT64                         *PageEntry;
  UINTN                          Index;
  UINTN                          CpuIndex;
  UINTN                          PageNumber;
  BOOLEAN                        NonStopMode;
 
  PFAddress = AsmReadCr2 () & ~EFI_PAGE_MASK;
  if (PFAddress < BASE_4KB) {
    NonStopMode = NULL_DETECTION_NONSTOP_MODE ? TRUE : FALSE;
  } else {
    NonStopMode = HEAP_GUARD_NONSTOP_MODE ? TRUE : FALSE;
  }
 
  if (NonStopMode) {
    MpInitLibWhoAmI (&CpuIndex);
    GetCurrentPagingContext (&PagingContext);
    //
    // Memory operation cross page boundary, like "rep mov" instruction, will
    // cause infinite loop between this and Debug Trap handler. We have to make
    // sure that current page and the page followed are both in PRESENT state.
    //
    PageNumber = 2;
    while (PageNumber > 0) {
      PageEntry = GetPageTableEntry (&PagingContext, PFAddress, &PageAttribute);
      ASSERT (PageEntry != NULL);
 
      if (PageEntry != NULL) {
        Attributes = GetAttributesFromPageEntry (PageEntry);
        if ((Attributes & EFI_MEMORY_RP) != 0) {
          Attributes &= ~EFI_MEMORY_RP;
          Status      = AssignMemoryPageAttributes (
                          &PagingContext,
                          PFAddress,
                          EFI_PAGE_SIZE,
                          Attributes,
                          NULL
                          );
          if (!EFI_ERROR (Status)) {
            Index = mPFEntryCount[CpuIndex];
            //
            // Re-retrieve page entry because above calling might update page
            // table due to table split.
            //
            PageEntry                              = GetPageTableEntry (&PagingContext, PFAddress, &PageAttribute);
            mLastPFEntryPointer[CpuIndex][Index++] = PageEntry;
            mPFEntryCount[CpuIndex]                = Index;
          }
        }
      }
 
      PFAddress += EFI_PAGE_SIZE;
      --PageNumber;
    }
  }
 
  //
  // Initialize the serial port before dumping.
  //
  SerialPortInitialize ();
  //
  // Display ExceptionType, CPU information and Image information
  //
  DumpCpuContext (ExceptionType, SystemContext);
  if (NonStopMode) {
    //
    // Set TF in EFLAGS
    //
    if (mPagingContext.MachineType == IMAGE_FILE_MACHINE_I386) {
      SystemContext.SystemContextIa32->Eflags |= (UINT32)BIT8;
    } else {
      SystemContext.SystemContextX64->Rflags |= (UINT64)BIT8;
    }
  } else {
    CpuDeadLoop ();
  }
}
 
VOID
InitializePageTableLib (
  VOID
  )
{
  PAGE_TABLE_LIB_PAGING_CONTEXT  CurrentPagingContext;
  UINT32                         *Attributes;
  UINTN                          *PageTableBase;
 
  GetCurrentPagingContext (&CurrentPagingContext);
 
  GetPagingDetails (&CurrentPagingContext.ContextData, &PageTableBase, &Attributes);
 
  //
  // Reserve memory of page tables for future uses, if paging is enabled.
  //
  if ((*PageTableBase != 0) &&
      ((*Attributes & PAGE_TABLE_LIB_PAGING_CONTEXT_IA32_X64_ATTRIBUTES_PAE) != 0))
  {
    DisableReadOnlyPageWriteProtect ();
    InitializePageTablePool (1);
    EnableReadOnlyPageWriteProtect ();
  }
 
  if (HEAP_GUARD_NONSTOP_MODE || NULL_DETECTION_NONSTOP_MODE) {
    mPFEntryCount = (UINTN *)AllocateZeroPool (sizeof (UINTN) * mNumberOfProcessors);
    ASSERT (mPFEntryCount != NULL);
 
    mLastPFEntryPointer = (UINT64 *(*)[MAX_PF_ENTRY_COUNT])
                          AllocateZeroPool (sizeof (mLastPFEntryPointer[0]) * mNumberOfProcessors);
    ASSERT (mLastPFEntryPointer != NULL);
  }
 
  DEBUG ((DEBUG_INFO, "CurrentPagingContext:\n"));
  DEBUG ((DEBUG_INFO, "  MachineType   - 0x%x\n", CurrentPagingContext.MachineType));
  DEBUG ((DEBUG_INFO, "  PageTableBase - 0x%Lx\n", (UINT64)*PageTableBase));
  DEBUG ((DEBUG_INFO, "  Attributes    - 0x%x\n", *Attributes));
 
  return;
}