system76-edk2/MdeModulePkg/Universal/Acpi/BootScriptExecutorDxe/X64/SetIdtEntry.c

/** @file
  Set a IDT entry for debug purpose

  Set a IDT entry for interrupt vector 3 for debug purpose for x64 platform

Copyright (c) 2006 - 2019, Intel Corporation. All rights reserved.<BR>
Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>


SPDX-License-Identifier: BSD-2-Clause-Patent

**/
#include "ScriptExecute.h"

//
// 8 extra pages for PF handler.
//
#define EXTRA_PAGE_TABLE_PAGES      8

#define IA32_PG_P                   BIT0
#define IA32_PG_RW                  BIT1
#define IA32_PG_PS                  BIT7

UINT64                              mPhyMask;
VOID                                *mOriginalHandler;
UINTN                               mPageFaultBuffer;
UINTN                               mPageFaultIndex = 0;
//
// Store the uplink information for each page being used.
//
UINT64                              *mPageFaultUplink[EXTRA_PAGE_TABLE_PAGES];

/**
  Page fault handler.

**/
VOID
EFIAPI
PageFaultHandlerHook (
  VOID
  );

/**
  Hook IDT with our page fault handler so that the on-demand paging works on page fault.

  @param  IdtEntry  a pointer to IDT entry

**/
VOID
HookPageFaultHandler (
  IN IA32_IDT_GATE_DESCRIPTOR                   *IdtEntry
  )
{
  UINT32         RegEax;
  UINT8          PhysicalAddressBits;
  UINTN          PageFaultHandlerHookAddress;

  AsmCpuid (0x80000000, &RegEax, NULL, NULL, NULL);
  if (RegEax >= 0x80000008) {
    AsmCpuid (0x80000008, &RegEax, NULL, NULL, NULL);
    PhysicalAddressBits = (UINT8) RegEax;
  } else {
    PhysicalAddressBits = 36;
  }
  mPhyMask = LShiftU64 (1, PhysicalAddressBits) - 1;
  mPhyMask &= (1ull << 48) - SIZE_4KB;

  //
  // Set Page Fault entry to catch >4G access
  //
  PageFaultHandlerHookAddress = (UINTN)PageFaultHandlerHook;
  mOriginalHandler = (VOID *)(UINTN)(LShiftU64 (IdtEntry->Bits.OffsetUpper, 32) + IdtEntry->Bits.OffsetLow + (IdtEntry->Bits.OffsetHigh << 16));
  IdtEntry->Bits.OffsetLow      = (UINT16)PageFaultHandlerHookAddress;
  IdtEntry->Bits.Selector       = (UINT16)AsmReadCs ();
  IdtEntry->Bits.Reserved_0     = 0;
  IdtEntry->Bits.GateType       = IA32_IDT_GATE_TYPE_INTERRUPT_32;
  IdtEntry->Bits.OffsetHigh     = (UINT16)(PageFaultHandlerHookAddress >> 16);
  IdtEntry->Bits.OffsetUpper    = (UINT32)(PageFaultHandlerHookAddress >> 32);
  IdtEntry->Bits.Reserved_1     = 0;

  if (mPage1GSupport) {
    mPageFaultBuffer = (UINTN)(AsmReadCr3 () & mPhyMask) + EFI_PAGES_TO_SIZE(2);
  }else {
    mPageFaultBuffer = (UINTN)(AsmReadCr3 () & mPhyMask) + EFI_PAGES_TO_SIZE(6);
  }
  ZeroMem (mPageFaultUplink, sizeof (mPageFaultUplink));
}

/**
  The function will check if current waking vector is long mode.

  @param  AcpiS3Context                 a pointer to a structure of ACPI_S3_CONTEXT

  @retval TRUE   Current context need long mode waking vector.
  @retval FALSE  Current context need not long mode waking vector.
**/
BOOLEAN
IsLongModeWakingVector (
  IN ACPI_S3_CONTEXT                *AcpiS3Context
  )
{
  EFI_ACPI_4_0_FIRMWARE_ACPI_CONTROL_STRUCTURE  *Facs;

  Facs = (EFI_ACPI_4_0_FIRMWARE_ACPI_CONTROL_STRUCTURE *) ((UINTN) (AcpiS3Context->AcpiFacsTable));
  if ((Facs == NULL) ||
      (Facs->Signature != EFI_ACPI_4_0_FIRMWARE_ACPI_CONTROL_STRUCTURE_SIGNATURE) ||
      ((Facs->FirmwareWakingVector == 0) && (Facs->XFirmwareWakingVector == 0)) ) {
    // Something wrong with FACS
    return FALSE;
  }
  if (Facs->XFirmwareWakingVector != 0) {
    if ((Facs->Version == EFI_ACPI_4_0_FIRMWARE_ACPI_CONTROL_STRUCTURE_VERSION) &&
        ((Facs->Flags & EFI_ACPI_4_0_64BIT_WAKE_SUPPORTED_F) != 0) &&
        ((Facs->OspmFlags & EFI_ACPI_4_0_OSPM_64BIT_WAKE__F) != 0)) {
      // Both BIOS and OS wants 64bit vector
      if (FeaturePcdGet (PcdDxeIplSwitchToLongMode)) {
        return TRUE;
      }
    }
  }
  return FALSE;
}

/**
  Set a IDT entry for interrupt vector 3 for debug purpose.

  @param  AcpiS3Context  a pointer to a structure of ACPI_S3_CONTEXT

**/
VOID
SetIdtEntry (
  IN ACPI_S3_CONTEXT     *AcpiS3Context
  )
{
  IA32_IDT_GATE_DESCRIPTOR                      *IdtEntry;
  IA32_DESCRIPTOR                               *IdtDescriptor;
  UINTN                                         S3DebugBuffer;
  EFI_STATUS                                    Status;

  //
  // Restore IDT for debug
  //
  IdtDescriptor = (IA32_DESCRIPTOR *) (UINTN) (AcpiS3Context->IdtrProfile);
  AsmWriteIdtr (IdtDescriptor);

  //
  // Setup the default CPU exception handlers
  //
  Status = InitializeCpuExceptionHandlers (NULL);
  ASSERT_EFI_ERROR (Status);

  DEBUG_CODE (
    //
    // Update IDT entry INT3 if the instruction is valid in it
    //
    S3DebugBuffer = (UINTN) (AcpiS3Context->S3DebugBufferAddress);
    if (*(UINTN *)S3DebugBuffer != (UINTN) -1) {
      IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *)(IdtDescriptor->Base + (3 * sizeof (IA32_IDT_GATE_DESCRIPTOR)));
      IdtEntry->Bits.OffsetLow      = (UINT16)S3DebugBuffer;
      IdtEntry->Bits.Selector       = (UINT16)AsmReadCs ();
      IdtEntry->Bits.Reserved_0     = 0;
      IdtEntry->Bits.GateType       = IA32_IDT_GATE_TYPE_INTERRUPT_32;
      IdtEntry->Bits.OffsetHigh     = (UINT16)(S3DebugBuffer >> 16);
      IdtEntry->Bits.OffsetUpper    = (UINT32)(S3DebugBuffer >> 32);
      IdtEntry->Bits.Reserved_1     = 0;
    }
  );

  //
  // If both BIOS and OS wants long mode waking vector,
  // S3ResumePei should have established 1:1 Virtual to Physical identity mapping page table,
  // no need to hook page fault handler.
  //
  if (!IsLongModeWakingVector (AcpiS3Context)) {
    IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *)(IdtDescriptor->Base + (14 * sizeof (IA32_IDT_GATE_DESCRIPTOR)));
    HookPageFaultHandler (IdtEntry);
  }
}

/**
  Acquire page for page fault.

  @param[in, out] Uplink        Pointer to up page table entry.

**/
VOID
AcquirePage (
  IN OUT UINT64                 *Uplink
  )
{
  UINTN             Address;

  Address = mPageFaultBuffer + EFI_PAGES_TO_SIZE (mPageFaultIndex);
  ZeroMem ((VOID *) Address, EFI_PAGES_TO_SIZE (1));

  //
  // Cut the previous uplink if it exists and wasn't overwritten.
  //
  if ((mPageFaultUplink[mPageFaultIndex] != NULL) &&
     ((*mPageFaultUplink[mPageFaultIndex] & ~mAddressEncMask & mPhyMask) == Address)) {
    *mPageFaultUplink[mPageFaultIndex] = 0;
  }

  //
  // Link & Record the current uplink.
  //
  *Uplink = Address | mAddressEncMask | IA32_PG_P | IA32_PG_RW;
  mPageFaultUplink[mPageFaultIndex] = Uplink;

  mPageFaultIndex = (mPageFaultIndex + 1) % EXTRA_PAGE_TABLE_PAGES;
}

/**
  The page fault handler that on-demand read >4G memory/MMIO.

  @retval TRUE     The page fault is correctly handled.
  @retval FALSE    The page fault is not handled and is passed through to original handler.

**/
BOOLEAN
EFIAPI
PageFaultHandler (
  VOID
  )
{
  UINT64         *PageTable;
  UINT64         PFAddress;
  UINTN          PTIndex;

  PFAddress = AsmReadCr2 ();
  DEBUG ((DEBUG_INFO, "BootScript - PageFaultHandler: Cr2 - %lx\n", PFAddress));

  if (PFAddress >= mPhyMask + SIZE_4KB) {
    return FALSE;
  }
  PFAddress &= mPhyMask;

  PageTable = (UINT64*)(UINTN)(AsmReadCr3 () & mPhyMask);

  PTIndex = BitFieldRead64 (PFAddress, 39, 47);
  // PML4E
  if ((PageTable[PTIndex] & IA32_PG_P) == 0) {
    AcquirePage (&PageTable[PTIndex]);
  }
  PageTable = (UINT64*)(UINTN)(PageTable[PTIndex] & ~mAddressEncMask & mPhyMask);
  PTIndex = BitFieldRead64 (PFAddress, 30, 38);
  // PDPTE
  if (mPage1GSupport) {
    PageTable[PTIndex] = ((PFAddress | mAddressEncMask) & ~((1ull << 30) - 1)) | IA32_PG_P | IA32_PG_RW | IA32_PG_PS;
  } else {
    if ((PageTable[PTIndex] & IA32_PG_P) == 0) {
      AcquirePage (&PageTable[PTIndex]);
    }
    PageTable = (UINT64*)(UINTN)(PageTable[PTIndex] & ~mAddressEncMask & mPhyMask);
    PTIndex = BitFieldRead64 (PFAddress, 21, 29);
    // PD
    PageTable[PTIndex] = ((PFAddress | mAddressEncMask) & ~((1ull << 21) - 1)) | IA32_PG_P | IA32_PG_RW | IA32_PG_PS;
  }

  return TRUE;
}