Processor.c

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#include <GdbStubInternal.h>
 
//
// Array of exception types that need to be hooked by the debugger
// {EFI mapping, GDB mapping}
//
EFI_EXCEPTION_TYPE_ENTRY  gExceptionType[] = {
  { EXCEPT_IA32_DIVIDE_ERROR,    GDB_SIGFPE  },
  { EXCEPT_IA32_DEBUG,           GDB_SIGTRAP },
  { EXCEPT_IA32_NMI,             GDB_SIGEMT  },
  { EXCEPT_IA32_BREAKPOINT,      GDB_SIGTRAP },
  { EXCEPT_IA32_OVERFLOW,        GDB_SIGSEGV },
  { EXCEPT_IA32_BOUND,           GDB_SIGSEGV },
  { EXCEPT_IA32_INVALID_OPCODE,  GDB_SIGILL  },
  { EXCEPT_IA32_DOUBLE_FAULT,    GDB_SIGEMT  },
  { EXCEPT_IA32_STACK_FAULT,     GDB_SIGSEGV },
  { EXCEPT_IA32_GP_FAULT,        GDB_SIGSEGV },
  { EXCEPT_IA32_PAGE_FAULT,      GDB_SIGSEGV },
  { EXCEPT_IA32_FP_ERROR,        GDB_SIGEMT  },
  { EXCEPT_IA32_ALIGNMENT_CHECK, GDB_SIGEMT  },
  { EXCEPT_IA32_MACHINE_CHECK,   GDB_SIGEMT  }
};
 
// The offsets of registers SystemContext.
// The fields in the array are in the gdb ordering.
//
// 16 regs
UINTN  gRegisterOffsets[] = {
  OFFSET_OF (EFI_SYSTEM_CONTEXT_IA32, Eax),
  OFFSET_OF (EFI_SYSTEM_CONTEXT_IA32, Ecx),
  OFFSET_OF (EFI_SYSTEM_CONTEXT_IA32, Edx),
  OFFSET_OF (EFI_SYSTEM_CONTEXT_IA32, Ebx),
  OFFSET_OF (EFI_SYSTEM_CONTEXT_IA32, Esp),
  OFFSET_OF (EFI_SYSTEM_CONTEXT_IA32, Ebp),
  OFFSET_OF (EFI_SYSTEM_CONTEXT_IA32, Esi),
  OFFSET_OF (EFI_SYSTEM_CONTEXT_IA32, Edi),
  OFFSET_OF (EFI_SYSTEM_CONTEXT_IA32, Eip),
  OFFSET_OF (EFI_SYSTEM_CONTEXT_IA32, Eflags),
  OFFSET_OF (EFI_SYSTEM_CONTEXT_IA32, Cs),
  OFFSET_OF (EFI_SYSTEM_CONTEXT_IA32, Ss),
  OFFSET_OF (EFI_SYSTEM_CONTEXT_IA32, Ds),
  OFFSET_OF (EFI_SYSTEM_CONTEXT_IA32, Es),
  OFFSET_OF (EFI_SYSTEM_CONTEXT_IA32, Fs),
  OFFSET_OF (EFI_SYSTEM_CONTEXT_IA32, Gs)
};
 
// Debug only..
VOID
PrintReg (
  IN EFI_SYSTEM_CONTEXT  SystemContext
  )
{
  Print ((CHAR16 *)L"EAX: %x ", SystemContext.SystemContextIa32->Eax);
  Print ((CHAR16 *)L"ECX: %x ", SystemContext.SystemContextIa32->Ecx);
  Print ((CHAR16 *)L"EDX: %x ", SystemContext.SystemContextIa32->Edx);
  Print ((CHAR16 *)L"EBX: %x ", SystemContext.SystemContextIa32->Ebx);
  Print ((CHAR16 *)L"ESP: %x ", SystemContext.SystemContextIa32->Esp);
  Print ((CHAR16 *)L"EBP: %x ", SystemContext.SystemContextIa32->Ebp);
  Print ((CHAR16 *)L"ESI: %x ", SystemContext.SystemContextIa32->Esi);
  Print ((CHAR16 *)L"EDI: %x ", SystemContext.SystemContextIa32->Edi);
  Print ((CHAR16 *)L"EIP: %x\n", SystemContext.SystemContextIa32->Eip);
  Print ((CHAR16 *)L"EFlags: %x\n", SystemContext.SystemContextIa32->Eflags);
}
 
// Debug only..
VOID
PrintDRreg (
  IN EFI_SYSTEM_CONTEXT  SystemContext
  )
{
  Print ((CHAR16 *)L"DR0: %x ", SystemContext.SystemContextIa32->Dr0);
  Print ((CHAR16 *)L"DR1: %x ", SystemContext.SystemContextIa32->Dr1);
  Print ((CHAR16 *)L"DR2: %x ", SystemContext.SystemContextIa32->Dr2);
  Print ((CHAR16 *)L"DR3: %x ", SystemContext.SystemContextIa32->Dr3);
  Print ((CHAR16 *)L"DR6: %x ", SystemContext.SystemContextIa32->Dr6);
  Print ((CHAR16 *)L"DR7: %x\n", SystemContext.SystemContextIa32->Dr7);
}
 
UINTN
MaxEfiException (
  VOID
  )
{
  return sizeof (gExceptionType)/sizeof (EFI_EXCEPTION_TYPE_ENTRY);
}
 
UINTN
MaxRegisterCount (
  VOID
  )
{
  return sizeof (gRegisterOffsets)/sizeof (UINTN);
}
 
BOOLEAN
CheckIsa (
  IN  EFI_INSTRUCTION_SET_ARCHITECTURE  Isa
  )
{
  return (BOOLEAN)(Isa == IsaIa32);
}
 
UINTN *
FindPointerToRegister (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN  UINTN               RegNumber
  )
{
  UINT8  *TempPtr;
 
  TempPtr = ((UINT8 *)SystemContext.SystemContextIa32) + gRegisterOffsets[RegNumber];
  return (UINTN *)TempPtr;
}
 
CHAR8 *
BasicReadRegister (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN  UINTN               RegNumber,
  IN  CHAR8               *OutBufPtr
  )
{
  UINTN  RegSize;
 
  RegSize = 0;
  while (RegSize < REG_SIZE) {
    *OutBufPtr++ = mHexToStr[((*FindPointerToRegister (SystemContext, RegNumber) >> (RegSize+4)) & 0xf)];
    *OutBufPtr++ = mHexToStr[((*FindPointerToRegister (SystemContext, RegNumber) >> RegSize) & 0xf)];
    RegSize      = RegSize + 8;
  }
 
  return OutBufPtr;
}
 
VOID
EFIAPI
ReadNthRegister (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN  CHAR8               *InBuffer
  )
{
  UINTN  RegNumber;
  CHAR8  OutBuffer[9]; // 1 reg=8 hex chars, and the end '\0' (escape seq)
  CHAR8  *OutBufPtr;   // pointer to the output buffer
 
  RegNumber = AsciiStrHexToUintn (&InBuffer[1]);
 
  if ((RegNumber < 0) || (RegNumber >= MaxRegisterCount ())) {
    SendError (GDB_EINVALIDREGNUM);
    return;
  }
 
  OutBufPtr = OutBuffer;
  OutBufPtr = BasicReadRegister (SystemContext, RegNumber, OutBufPtr);
 
  *OutBufPtr = '\0';  // the end of the buffer
  SendPacket (OutBuffer);
}
 
VOID
EFIAPI
ReadGeneralRegisters (
  IN  EFI_SYSTEM_CONTEXT  SystemContext
  )
{
  UINTN  i;
  CHAR8  OutBuffer[129]; // 16 regs, 8 hex chars each, and the end '\0' (escape seq)
  CHAR8  *OutBufPtr;     // pointer to the output buffer
 
  OutBufPtr = OutBuffer;
  for (i = 0; i < MaxRegisterCount (); i++) {
    // there are only 16 registers to read
    OutBufPtr = BasicReadRegister (SystemContext, i, OutBufPtr);
  }
 
  *OutBufPtr = '\0';  // the end of the buffer
  SendPacket (OutBuffer);
}
 
CHAR8 *
BasicWriteRegister (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN  UINTN               RegNumber,
  IN  CHAR8               *InBufPtr
  )
{
  UINTN   RegSize;
  UINTN   TempValue; // the value transferred from a hex char
  UINT32  NewValue;  // the new value of the RegNumber-th Register
 
  NewValue = 0;
  RegSize  = 0;
  while (RegSize < REG_SIZE) {
    TempValue = HexCharToInt (*InBufPtr++);
 
    if (TempValue < 0) {
      SendError (GDB_EBADMEMDATA);
      return NULL;
    }
 
    NewValue += (TempValue << (RegSize+4));
    TempValue = HexCharToInt (*InBufPtr++);
 
    if (TempValue < 0) {
      SendError (GDB_EBADMEMDATA);
      return NULL;
    }
 
    NewValue += (TempValue << RegSize);
    RegSize   = RegSize + 8;
  }
 
  *(FindPointerToRegister (SystemContext, RegNumber)) = NewValue;
  return InBufPtr;
}
 
VOID
EFIAPI
WriteNthRegister (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN  CHAR8               *InBuffer
  )
{
  UINTN  RegNumber;
  CHAR8  RegNumBuffer[MAX_REG_NUM_BUF_SIZE]; // put the 'n..' part of the message into this array
  CHAR8  *RegNumBufPtr;
  CHAR8  *InBufPtr; // pointer to the input buffer
 
  // find the register number to write
  InBufPtr     = &InBuffer[1];
  RegNumBufPtr = RegNumBuffer;
  while (*InBufPtr != '=') {
    *RegNumBufPtr++ = *InBufPtr++;
  }
 
  *RegNumBufPtr = '\0';
  RegNumber     = AsciiStrHexToUintn (RegNumBuffer);
 
  // check if this is a valid Register Number
  if ((RegNumber < 0) || (RegNumber >= MaxRegisterCount ())) {
    SendError (GDB_EINVALIDREGNUM);
    return;
  }
 
  InBufPtr++;  // skips the '=' character
  BasicWriteRegister (SystemContext, RegNumber, InBufPtr);
  SendSuccess ();
}
 
VOID
EFIAPI
WriteGeneralRegisters (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN  CHAR8               *InBuffer
  )
{
  UINTN  i;
  CHAR8  *InBufPtr; 
 
  // check to see if the buffer is the right size which is
  // 1 (for 'G') + 16 (for 16 registers) * 8 ( for 8 hex chars each) = 129
  if (AsciiStrLen (InBuffer) != 129) {
    // 16 regs, 8 hex chars each, and the end '\0' (escape seq)
    // Bad message. Message is not the right length
    SendError (GDB_EBADBUFSIZE);
    return;
  }
 
  InBufPtr = &InBuffer[1];
 
  // Read the new values for the registers from the input buffer to an array, NewValueArray.
  // The values in the array are in the gdb ordering
  for (i = 0; i < MaxRegisterCount (); i++) {
    // there are only 16 registers to write
    InBufPtr = BasicWriteRegister (SystemContext, i, InBufPtr);
  }
 
  SendSuccess ();
}
 
VOID
AddSingleStep (
  IN  EFI_SYSTEM_CONTEXT  SystemContext
  )
{
  SystemContext.SystemContextIa32->Eflags |= TF_BIT; // Setting the TF bit.
}
 
VOID
RemoveSingleStep (
  IN  EFI_SYSTEM_CONTEXT  SystemContext
  )
{
  SystemContext.SystemContextIa32->Eflags &= ~TF_BIT;  // clearing the TF bit.
}
 
VOID
EFIAPI
ContinueAtAddress (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN    CHAR8             *PacketData
  )
{
  if (PacketData[1] != '\0') {
    SystemContext.SystemContextIa32->Eip = AsciiStrHexToUintn (&PacketData[1]);
  }
}
 
VOID
EFIAPI
SingleStep (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN    CHAR8             *PacketData
  )
{
  if (PacketData[1] != '\0') {
    SystemContext.SystemContextIa32->Eip = AsciiStrHexToUintn (&PacketData[1]);
  }
 
  AddSingleStep (SystemContext);
}
 
UINTN
GetBreakpointDataAddress (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN  UINTN               BreakpointNumber
  )
{
  UINTN  Address;
 
  if (BreakpointNumber == 1) {
    Address = SystemContext.SystemContextIa32->Dr0;
  } else if (BreakpointNumber == 2) {
    Address = SystemContext.SystemContextIa32->Dr1;
  } else if (BreakpointNumber == 3) {
    Address = SystemContext.SystemContextIa32->Dr2;
  } else if (BreakpointNumber == 4) {
    Address = SystemContext.SystemContextIa32->Dr3;
  } else {
    Address = 0;
  }
 
  return Address;
}
 
UINTN
GetBreakpointDetected (
  IN  EFI_SYSTEM_CONTEXT  SystemContext
  )
{
  IA32_DR6  Dr6;
  UINTN     BreakpointNumber;
 
  Dr6.UintN = SystemContext.SystemContextIa32->Dr6;
 
  if (Dr6.Bits.B0 == 1) {
    BreakpointNumber = 1;
  } else if (Dr6.Bits.B1 == 1) {
    BreakpointNumber = 2;
  } else if (Dr6.Bits.B2 == 1) {
    BreakpointNumber = 3;
  } else if (Dr6.Bits.B3 == 1) {
    BreakpointNumber = 4;
  } else {
    BreakpointNumber = 0;  // No breakpoint detected
  }
 
  return BreakpointNumber;
}
 
BREAK_TYPE
GetBreakpointType (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN  UINTN               BreakpointNumber
  )
{
  IA32_DR7    Dr7;
  BREAK_TYPE  Type = NotSupported; // Default is NotSupported type
 
  Dr7.UintN = SystemContext.SystemContextIa32->Dr7;
 
  if (BreakpointNumber == 1) {
    Type = (BREAK_TYPE)Dr7.Bits.RW0;
  } else if (BreakpointNumber == 2) {
    Type = (BREAK_TYPE)Dr7.Bits.RW1;
  } else if (BreakpointNumber == 3) {
    Type = (BREAK_TYPE)Dr7.Bits.RW2;
  } else if (BreakpointNumber == 4) {
    Type = (BREAK_TYPE)Dr7.Bits.RW3;
  }
 
  return Type;
}
 
UINTN
ConvertLengthData (
  IN     UINTN  Length
  )
{
  if (Length == 1) {
    // 1-Byte length
    return 0;
  } else if (Length == 2) {
    // 2-Byte length
    return 1;
  } else if (Length == 4) {
    // 4-Byte length
    return 3;
  } else {
    // Undefined or 8-byte length
    return 2;
  }
}
 
EFI_STATUS
FindNextFreeDebugRegister (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  OUT UINTN               *Register
  )
{
  IA32_DR7  Dr7;
 
  Dr7.UintN = SystemContext.SystemContextIa32->Dr7;
 
  if (Dr7.Bits.G0 == 0) {
    *Register = 0;
  } else if (Dr7.Bits.G1 == 0) {
    *Register = 1;
  } else if (Dr7.Bits.G2 == 0) {
    *Register = 2;
  } else if (Dr7.Bits.G3 == 0) {
    *Register = 3;
  } else {
    return EFI_OUT_OF_RESOURCES;
  }
 
  return EFI_SUCCESS;
}
 
EFI_STATUS
EnableDebugRegister (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN  UINTN               Register,
  IN  UINTN               Address,
  IN  UINTN               Length,
  IN  UINTN               Type
  )
{
  IA32_DR7  Dr7;
 
  // Convert length data
  Length = ConvertLengthData (Length);
 
  // For Instruction execution, length should be 0
  // (Ref. Intel reference manual 18.2.4)
  if ((Type == 0) && (Length != 0)) {
    return EFI_INVALID_PARAMETER;
  }
 
  // Hardware doesn't support ReadWatch (z3 packet) type. GDB can handle
  // software breakpoint. We should send empty packet in both these cases.
  if ((Type == (BREAK_TYPE)DataRead) ||
      (Type == (BREAK_TYPE)SoftwareBreakpoint))
  {
    return EFI_UNSUPPORTED;
  }
 
  // Read DR7 so appropriate Gn, RWn and LENn bits can be modified.
  Dr7.UintN = SystemContext.SystemContextIa32->Dr7;
 
  if (Register == 0) {
    SystemContext.SystemContextIa32->Dr0 = Address;
    Dr7.Bits.G0                          = 1;
    Dr7.Bits.RW0                         = Type;
    Dr7.Bits.LEN0                        = Length;
  } else if (Register == 1) {
    SystemContext.SystemContextIa32->Dr1 = Address;
    Dr7.Bits.G1                          = 1;
    Dr7.Bits.RW1                         = Type;
    Dr7.Bits.LEN1                        = Length;
  } else if (Register == 2) {
    SystemContext.SystemContextIa32->Dr2 = Address;
    Dr7.Bits.G2                          = 1;
    Dr7.Bits.RW2                         = Type;
    Dr7.Bits.LEN2                        = Length;
  } else if (Register == 3) {
    SystemContext.SystemContextIa32->Dr3 = Address;
    Dr7.Bits.G3                          = 1;
    Dr7.Bits.RW3                         = Type;
    Dr7.Bits.LEN3                        = Length;
  } else {
    return EFI_INVALID_PARAMETER;
  }
 
  // Update Dr7 with appropriate Gn, RWn and LENn bits
  SystemContext.SystemContextIa32->Dr7 = Dr7.UintN;
 
  return EFI_SUCCESS;
}
 
EFI_STATUS
FindMatchingDebugRegister (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN  UINTN               Address,
  IN  UINTN               Length,
  IN  UINTN               Type,
  OUT UINTN               *Register
  )
{
  IA32_DR7  Dr7;
 
  // Hardware doesn't support ReadWatch (z3 packet) type. GDB can handle
  // software breakpoint. We should send empty packet in both these cases.
  if ((Type == (BREAK_TYPE)DataRead) ||
      (Type == (BREAK_TYPE)SoftwareBreakpoint))
  {
    return EFI_UNSUPPORTED;
  }
 
  // Convert length data
  Length = ConvertLengthData (Length);
 
  Dr7.UintN = SystemContext.SystemContextIa32->Dr7;
 
  if ((Dr7.Bits.G0 == 1) &&
      (Dr7.Bits.LEN0 == Length) &&
      (Dr7.Bits.RW0 == Type) &&
      (Address == SystemContext.SystemContextIa32->Dr0))
  {
    *Register = 0;
  } else if ((Dr7.Bits.G1 == 1) &&
             (Dr7.Bits.LEN1 == Length) &&
             (Dr7.Bits.RW1 == Type) &&
             (Address == SystemContext.SystemContextIa32->Dr1))
  {
    *Register = 1;
  } else if ((Dr7.Bits.G2 == 1) &&
             (Dr7.Bits.LEN2 == Length) &&
             (Dr7.Bits.RW2 == Type) &&
             (Address == SystemContext.SystemContextIa32->Dr2))
  {
    *Register = 2;
  } else if ((Dr7.Bits.G3 == 1) &&
             (Dr7.Bits.LEN3 == Length) &&
             (Dr7.Bits.RW3 == Type) &&
             (Address == SystemContext.SystemContextIa32->Dr3))
  {
    *Register = 3;
  } else {
    Print ((CHAR16 *)L"No match found..\n");
    return EFI_NOT_FOUND;
  }
 
  return EFI_SUCCESS;
}
 
EFI_STATUS
DisableDebugRegister (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN  UINTN               Register
  )
{
  IA32_DR7  Dr7;
  UINTN     Address = 0;
 
  // Read DR7 register so appropriate Gn, RWn and LENn bits can be turned off.
  Dr7.UintN = SystemContext.SystemContextIa32->Dr7;
 
  if (Register == 0) {
    SystemContext.SystemContextIa32->Dr0 = Address;
    Dr7.Bits.G0                          = 0;
    Dr7.Bits.RW0                         = 0;
    Dr7.Bits.LEN0                        = 0;
  } else if (Register == 1) {
    SystemContext.SystemContextIa32->Dr1 = Address;
    Dr7.Bits.G1                          = 0;
    Dr7.Bits.RW1                         = 0;
    Dr7.Bits.LEN1                        = 0;
  } else if (Register == 2) {
    SystemContext.SystemContextIa32->Dr2 = Address;
    Dr7.Bits.G2                          = 0;
    Dr7.Bits.RW2                         = 0;
    Dr7.Bits.LEN2                        = 0;
  } else if (Register == 3) {
    SystemContext.SystemContextIa32->Dr3 = Address;
    Dr7.Bits.G3                          = 0;
    Dr7.Bits.RW3                         = 0;
    Dr7.Bits.LEN3                        = 0;
  } else {
    return EFI_INVALID_PARAMETER;
  }
 
  // Update DR7 register so appropriate Gn, RWn and LENn bits can be turned off.
  SystemContext.SystemContextIa32->Dr7 = Dr7.UintN;
 
  return EFI_SUCCESS;
}
 
VOID
EFIAPI
InsertBreakPoint (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN  CHAR8               *PacketData
  )
{
  UINTN       Type;
  UINTN       Address;
  UINTN       Length;
  UINTN       Register;
  EFI_STATUS  Status;
  BREAK_TYPE  BreakType = NotSupported;
  UINTN       ErrorCode;
 
  ErrorCode = ParseBreakpointPacket (PacketData, &Type, &Address, &Length);
  if (ErrorCode > 0) {
    SendError ((UINT8)ErrorCode);
    return;
  }
 
  switch (Type) {
    case 0:      // Software breakpoint
      BreakType = SoftwareBreakpoint;
      break;
 
    case 1:      // Hardware breakpoint
      BreakType = InstructionExecution;
      break;
 
    case 2:      // Write watchpoint
      BreakType = DataWrite;
      break;
 
    case 3:      // Read watchpoint
      BreakType = DataRead;
      break;
 
    case 4:      // Access watchpoint
      BreakType = DataReadWrite;
      break;
 
    default:
      Print ((CHAR16 *)L"Insert breakpoint default: %x\n", Type);
      SendError (GDB_EINVALIDBRKPOINTTYPE);
      return;
  }
 
  // Find next free debug register
  Status = FindNextFreeDebugRegister (SystemContext, &Register);
  if (EFI_ERROR (Status)) {
    Print ((CHAR16 *)L"No space left on device\n");
    SendError (GDB_ENOSPACE);
    return;
  }
 
  // Write Address, length data at particular DR register
  Status = EnableDebugRegister (SystemContext, Register, Address, Length, (UINTN)BreakType);
  if (EFI_ERROR (Status)) {
    if (Status == EFI_UNSUPPORTED) {
      Print ((CHAR16 *)L"Not supported\n");
      SendNotSupported ();
      return;
    }
 
    Print ((CHAR16 *)L"Invalid argument\n");
    SendError (GDB_EINVALIDARG);
    return;
  }
 
  SendSuccess ();
}
 
VOID
EFIAPI
RemoveBreakPoint (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN  CHAR8               *PacketData
  )
{
  UINTN       Type;
  UINTN       Address;
  UINTN       Length;
  UINTN       Register;
  BREAK_TYPE  BreakType = NotSupported;
  EFI_STATUS  Status;
  UINTN       ErrorCode;
 
  // Parse breakpoint packet data
  ErrorCode = ParseBreakpointPacket (PacketData, &Type, &Address, &Length);
  if (ErrorCode > 0) {
    SendError ((UINT8)ErrorCode);
    return;
  }
 
  switch (Type) {
    case 0:      // Software breakpoint
      BreakType = SoftwareBreakpoint;
      break;
 
    case 1:      // Hardware breakpoint
      BreakType = InstructionExecution;
      break;
 
    case 2:      // Write watchpoint
      BreakType = DataWrite;
      break;
 
    case 3:      // Read watchpoint
      BreakType = DataRead;
      break;
 
    case 4:      // Access watchpoint
      BreakType = DataReadWrite;
      break;
 
    default:
      SendError (GDB_EINVALIDBRKPOINTTYPE);
      return;
  }
 
  // Find matching debug register
  Status = FindMatchingDebugRegister (SystemContext, Address, Length, (UINTN)BreakType, &Register);
  if (EFI_ERROR (Status)) {
    if (Status == EFI_UNSUPPORTED) {
      Print ((CHAR16 *)L"Not supported.\n");
      SendNotSupported ();
      return;
    }
 
    Print ((CHAR16 *)L"No matching register found.\n");
    SendError (GDB_ENOSPACE);
    return;
  }
 
  // Remove breakpoint
  Status = DisableDebugRegister (SystemContext, Register);
  if (EFI_ERROR (Status)) {
    Print ((CHAR16 *)L"Invalid argument.\n");
    SendError (GDB_EINVALIDARG);
    return;
  }
 
  SendSuccess ();
}
 
VOID
InitializeProcessor (
  VOID
  )
{
}
 
BOOLEAN
ValidateAddress (
  IN  VOID  *Address
  )
{
  return TRUE;
}
 
BOOLEAN
ValidateException (
  IN  EFI_EXCEPTION_TYPE     ExceptionType,
  IN OUT EFI_SYSTEM_CONTEXT  SystemContext
  )
{
  return TRUE;
}