GdbStub/Arm/Processor.c

/** @file
  Processor specific parts of the GDB stub

  Copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>

  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 <GdbStubInternal.h>
#include <Library/CacheMaintenanceLib.h>
#include <Library/PrintLib.h>

//
// Array of exception types that need to be hooked by the debugger
// (efi, gdb) //efi number
//
EFI_EXCEPTION_TYPE_ENTRY gExceptionType[] = {
  { EXCEPT_ARM_SOFTWARE_INTERRUPT,  GDB_SIGTRAP }
//  { EXCEPT_ARM_UNDEFINED_INSTRUCTION, GDB_SIGTRAP },
//  { EXCEPT_ARM_PREFETCH_ABORT,        GDB_SIGTRAP },
//  { EXCEPT_ARM_DATA_ABORT,            GDB_SIGEMT  },
//  { EXCEPT_ARM_RESERVED,              GDB_SIGILL  }
};

// Shut up some annoying RVCT warnings
#ifdef __CC_ARM
#pragma diag_suppress 1296
#endif

UINTN gRegisterOffsets[] = {
  OFFSET_OF(EFI_SYSTEM_CONTEXT_ARM, R0),
  OFFSET_OF(EFI_SYSTEM_CONTEXT_ARM, R1),
  OFFSET_OF(EFI_SYSTEM_CONTEXT_ARM, R2),
  OFFSET_OF(EFI_SYSTEM_CONTEXT_ARM, R3),
  OFFSET_OF(EFI_SYSTEM_CONTEXT_ARM, R4),
  OFFSET_OF(EFI_SYSTEM_CONTEXT_ARM, R5),
  OFFSET_OF(EFI_SYSTEM_CONTEXT_ARM, R6),
  OFFSET_OF(EFI_SYSTEM_CONTEXT_ARM, R7),
  OFFSET_OF(EFI_SYSTEM_CONTEXT_ARM, R8),
  OFFSET_OF(EFI_SYSTEM_CONTEXT_ARM, R9),
  OFFSET_OF(EFI_SYSTEM_CONTEXT_ARM, R10),
  OFFSET_OF(EFI_SYSTEM_CONTEXT_ARM, R11),
  OFFSET_OF(EFI_SYSTEM_CONTEXT_ARM, R12),
  OFFSET_OF(EFI_SYSTEM_CONTEXT_ARM, SP),
  OFFSET_OF(EFI_SYSTEM_CONTEXT_ARM, LR),
  OFFSET_OF(EFI_SYSTEM_CONTEXT_ARM, PC),
  0x00000F01,                               // f0
  0x00000F02,
  0x00000F03,
  0x00000F11,                               // f1
  0x00000F12,
  0x00000F13,
  0x00000F21,                               // f2
  0x00000F22,
  0x00000F23,
  0x00000F31,                               // f3
  0x00000F32,
  0x00000F33,
  0x00000F41,                               // f4
  0x00000F42,
  0x00000F43,
  0x00000F51,                               // f5
  0x00000F52,
  0x00000F53,
  0x00000F61,                               // f6
  0x00000F62,
  0x00000F63,
  0x00000F71,                               // f7
  0x00000F72,
  0x00000F73,
  0x00000FFF,                               // fps
  OFFSET_OF(EFI_SYSTEM_CONTEXT_ARM, CPSR)
};

// restore warnings for RVCT
#ifdef __CC_ARM
#pragma diag_default 1296
#endif

/**
 Return the number of entries in the gExceptionType[]

 @retval  UINTN, the number of entries in the gExceptionType[] array.
 **/
UINTN
MaxEfiException (
  VOID
  )
{
  return sizeof (gExceptionType) / sizeof (EFI_EXCEPTION_TYPE_ENTRY);
}


/**
 Return the number of entries in the gRegisters[]

 @retval  UINTN, the number of entries (registers) in the gRegisters[] array.
 **/
UINTN
MaxRegisterCount (
  VOID
  )
{
  return sizeof (gRegisterOffsets) / sizeof (UINTN);
}


/**
 Check to see if the ISA is supported.
 ISA = Instruction Set Architecture

 @retval TRUE if Isa is supported

**/
BOOLEAN
CheckIsa (
  IN  EFI_INSTRUCTION_SET_ARCHITECTURE  Isa
  )
{
  if (Isa == IsaArm) {
    return TRUE;
  } else {
    return FALSE;
  }
}


/**
 This takes in the register number and the System Context, and returns a pointer to the RegNumber-th register in gdb ordering
 It is, by default, set to find the register pointer of the ARM member
 @param   SystemContext     Register content at time of the exception
 @param   RegNumber       The register to which we want to find a pointer
 @retval  the pointer to the RegNumber-th pointer
 **/
UINTN *
FindPointerToRegister (
  IN  EFI_SYSTEM_CONTEXT      SystemContext,
  IN  UINTN           RegNumber
  )
{
  UINT8 *TempPtr;
  ASSERT(gRegisterOffsets[RegNumber] < 0xF00);
  TempPtr = ((UINT8 *)SystemContext.SystemContextArm) + gRegisterOffsets[RegNumber];
  return (UINT32 *)TempPtr;
}


/**
 Adds the RegNumber-th register's value to the output buffer, starting at the given OutBufPtr
 @param SystemContext     Register content at time of the exception
 @param   RegNumber       the number of the register that we want to read
 @param   OutBufPtr       pointer to the output buffer's end. the new data will be added from this point on.
 @retval  the pointer to the next character of the output buffer that is available to be written on.
 **/
CHAR8 *
BasicReadRegister (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN  UINTN               RegNumber,
  IN  CHAR8               *OutBufPtr
  )
{
  UINTN RegSize;
  CHAR8 Char;

  if (gRegisterOffsets[RegNumber] > 0xF00) {
    AsciiSPrint (OutBufPtr, 9, "00000000");
    OutBufPtr += 8;
    return OutBufPtr;
  }

  RegSize = 0;
  while (RegSize < 32) {
    Char = mHexToStr[(UINT8)((*FindPointerToRegister (SystemContext, RegNumber) >> (RegSize+4)) & 0xf)];
    if ((Char >= 'A') && (Char <= 'F')) {
      Char = Char - 'A' + 'a';
    }
    *OutBufPtr++ = Char;

    Char = mHexToStr[(UINT8)((*FindPointerToRegister (SystemContext, RegNumber) >> RegSize) & 0xf)];
    if ((Char >= 'A') && (Char <= 'F')) {
      Char = Char - 'A' + 'a';
    }
    *OutBufPtr++ = Char;

    RegSize = RegSize + 8;
  }
  return OutBufPtr;
}


/**
 Reads the n-th register's value into an output buffer and sends it as a packet
 @param   SystemContext   Register content at time of the exception
 @param   InBuffer      Pointer to the input buffer received from gdb server
 **/
VOID
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 >= MaxRegisterCount ()) {
    SendError (GDB_EINVALIDREGNUM);
    return;
  }

  OutBufPtr = OutBuffer;
  OutBufPtr = BasicReadRegister (SystemContext, RegNumber, OutBufPtr);

  *OutBufPtr = '\0';  // the end of the buffer
  SendPacket (OutBuffer);
}


/**
 Reads the general registers into an output buffer  and sends it as a packet
 @param   SystemContext     Register content at time of the exception
 **/
VOID
EFIAPI
ReadGeneralRegisters (
  IN  EFI_SYSTEM_CONTEXT      SystemContext
  )
{
  UINTN   Index;
  CHAR8   *OutBuffer;
  CHAR8   *OutBufPtr;
  UINTN   RegisterCount = MaxRegisterCount ();

  // It is not safe to allocate pool here....
  OutBuffer = AllocatePool ((RegisterCount * 8) + 1); // 8 bytes per register in string format plus a null to terminate
  OutBufPtr = OutBuffer;
  for (Index = 0; Index < RegisterCount; Index++) {
    OutBufPtr = BasicReadRegister (SystemContext, Index, OutBufPtr);
  }

  *OutBufPtr = '\0';
  SendPacket (OutBuffer);
  FreePool (OutBuffer);
}


/**
 Adds the RegNumber-th register's value to the output buffer, starting at the given OutBufPtr
 @param   SystemContext       Register content at time of the exception
 @param   RegNumber         the number of the register that we want to write
 @param   InBufPtr          pointer to the output buffer. the new data will be extracted from the input buffer from this point on.
 @retval  the pointer to the next character of the input buffer that can be used
 **/
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

  if (gRegisterOffsets[RegNumber] > 0xF00) {
    return InBufPtr + 8;
  }

  NewValue = 0;
  RegSize = 0;
  while (RegSize < 32) {
    TempValue = HexCharToInt (*InBufPtr++);

    if ((INTN)TempValue < 0) {
      SendError (GDB_EBADMEMDATA);
      return NULL;
    }

    NewValue += (TempValue << (RegSize+4));
    TempValue = HexCharToInt (*InBufPtr++);

    if ((INTN)TempValue < 0) {
      SendError (GDB_EBADMEMDATA);
      return NULL;
    }

    NewValue += (TempValue << RegSize);
    RegSize = RegSize + 8;
  }
  *(FindPointerToRegister (SystemContext, RegNumber)) = NewValue;
  return InBufPtr;
}


/** ‘P n...=r...’
 Writes the new value of n-th register received into the input buffer to the n-th register
 @param   SystemContext   Register content at time of the exception
 @param   InBuffer      Ponter to the input buffer received from gdb server
 **/
VOID
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 >= MaxRegisterCount ()) {
    SendError (GDB_EINVALIDREGNUM);
    return;
  }
  InBufPtr++;  // skips the '=' character
  BasicWriteRegister (SystemContext, RegNumber, InBufPtr);
  SendSuccess();
}


/** ‘G XX...’
 Writes the new values received into the input buffer to the general registers
 @param   SystemContext       Register content at time of the exception
 @param   InBuffer          Pointer to the input buffer received from gdb server
 **/

VOID
EFIAPI
WriteGeneralRegisters (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN  CHAR8               *InBuffer
  )
{
  UINTN  i;
  CHAR8  *InBufPtr; /// pointer to the input buffer
  UINTN  MinLength;
  UINTN  RegisterCount = MaxRegisterCount ();

  MinLength = (RegisterCount * 8) + 1;  // 'G' plus the registers in ASCII format

  if (AsciiStrLen (InBuffer) < MinLength) {
    //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 < RegisterCount; i++) {
    InBufPtr = BasicWriteRegister (SystemContext, i, InBufPtr);
  }

  SendSuccess ();
}

// What about Thumb?
// Use SWI 0xdbdbdb as the debug instruction
#define GDB_ARM_BKPT    0xefdbdbdb

BOOLEAN mSingleStepActive = FALSE;
UINT32  mSingleStepPC;
UINT32  mSingleStepData;
UINTN   mSingleStepDataSize;

typedef struct {
  LIST_ENTRY  Link;
  UINT64      Signature;
  UINT32      Address;
  UINT32      Instruction;
} ARM_SOFTWARE_BREAKPOINT;

#define ARM_SOFTWARE_BREAKPOINT_SIGNATURE     SIGNATURE_64('A', 'R', 'M', 'B', 'R', 'K', 'P', 'T')
#define ARM_SOFTWARE_BREAKPOINT_FROM_LINK(a)  CR(a, ARM_SOFTWARE_BREAKPOINT, Link, ARM_SOFTWARE_BREAKPOINT_SIGNATURE)

LIST_ENTRY  BreakpointList;

/**
 Insert Single Step in the SystemContext

 @param SystemContext  Register content at time of the exception
 **/
VOID
AddSingleStep (
  IN EFI_SYSTEM_CONTEXT SystemContext
  )
{
  if (mSingleStepActive) {
    // Currently don't support nesting
    return;
  }
  mSingleStepActive = TRUE;

  mSingleStepPC = SystemContext.SystemContextArm->PC;

  mSingleStepDataSize = sizeof (UINT32);
  mSingleStepData = (*(UINT32 *)mSingleStepPC);
  *(UINT32 *)mSingleStepPC = GDB_ARM_BKPT;
  if (*(UINT32 *)mSingleStepPC != GDB_ARM_BKPT) {
    // For some reason our breakpoint did not take
    mSingleStepActive = FALSE;
  }

  InvalidateInstructionCacheRange ((VOID *)mSingleStepPC, mSingleStepDataSize);
  //DEBUG((EFI_D_ERROR, "AddSingleStep at 0x%08x (was: 0x%08x is:0x%08x)\n", SystemContext.SystemContextArm->PC, mSingleStepData, *(UINT32 *)mSingleStepPC));
}


/**
 Remove Single Step in the SystemContext

 @param SystemContext  Register content at time of the exception
 **/
VOID
RemoveSingleStep (
  IN  EFI_SYSTEM_CONTEXT  SystemContext
  )
{
  if (!mSingleStepActive) {
    return;
  }

  if (mSingleStepDataSize == sizeof (UINT16)) {
    *(UINT16 *)mSingleStepPC = (UINT16)mSingleStepData;
  } else {
    //DEBUG((EFI_D_ERROR, "RemoveSingleStep at 0x%08x (was: 0x%08x is:0x%08x)\n", SystemContext.SystemContextArm->PC, *(UINT32 *)mSingleStepPC, mSingleStepData));
    *(UINT32 *)mSingleStepPC = mSingleStepData;
  }
  InvalidateInstructionCacheRange ((VOID *)mSingleStepPC, mSingleStepDataSize);
  mSingleStepActive = FALSE;
}


/**
 Continue. addr is Address to resume. If addr is omitted, resume at current
 Address.

 @param   SystemContext     Register content at time of the exception
 **/
VOID
EFIAPI
ContinueAtAddress (
  IN  EFI_SYSTEM_CONTEXT      SystemContext,
  IN    CHAR8                 *PacketData
  )
{
  if (PacketData[1] != '\0') {
    SystemContext.SystemContextArm->PC = AsciiStrHexToUintn (&PacketData[1]);
  }
}


/** ‘s [addr ]’
 Single step. addr is the Address at which to resume. If addr is omitted, resume
 at same Address.

 @param   SystemContext     Register content at time of the exception
 **/
VOID
EFIAPI
SingleStep (
  IN  EFI_SYSTEM_CONTEXT      SystemContext,
  IN    CHAR8                       *PacketData
  )
{
  SendNotSupported ();
}

UINTN
GetBreakpointDataAddress (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN  UINTN               BreakpointNumber
  )
{
  return 0;
}

UINTN
GetBreakpointDetected (
  IN  EFI_SYSTEM_CONTEXT  SystemContext
  )
{
  return 0;
}

BREAK_TYPE
GetBreakpointType (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN  UINTN               BreakpointNumber
  )
{
  return NotSupported;
}

ARM_SOFTWARE_BREAKPOINT *
SearchBreakpointList (
  IN  UINT32  Address
  )
{
  LIST_ENTRY              *Current;
  ARM_SOFTWARE_BREAKPOINT *Breakpoint;

  Current = GetFirstNode (&BreakpointList);
  while (!IsNull (&BreakpointList, Current)) {
    Breakpoint = ARM_SOFTWARE_BREAKPOINT_FROM_LINK(Current);

    if (Address == Breakpoint->Address) {
      return Breakpoint;
    }

    Current = GetNextNode (&BreakpointList, Current);
  }

  return NULL;
}

VOID
SetBreakpoint (
  IN UINT32 Address
  )
{
  ARM_SOFTWARE_BREAKPOINT *Breakpoint;

  Breakpoint = SearchBreakpointList (Address);

  if (Breakpoint != NULL) {
    return;
  }

  // create and fill breakpoint structure
  Breakpoint = AllocatePool (sizeof(ARM_SOFTWARE_BREAKPOINT));

  Breakpoint->Signature   = ARM_SOFTWARE_BREAKPOINT_SIGNATURE;
  Breakpoint->Address     = Address;
  Breakpoint->Instruction = *(UINT32 *)Address;

  // Add it to the list
  InsertTailList (&BreakpointList, &Breakpoint->Link);

  // Insert the software breakpoint
  *(UINT32 *)Address = GDB_ARM_BKPT;
  InvalidateInstructionCacheRange ((VOID *)Address, 4);

  //DEBUG((EFI_D_ERROR, "SetBreakpoint at 0x%08x (was: 0x%08x is:0x%08x)\n", Address, Breakpoint->Instruction, *(UINT32 *)Address));
}

VOID
ClearBreakpoint (
  IN UINT32 Address
  )
{
  ARM_SOFTWARE_BREAKPOINT *Breakpoint;

  Breakpoint = SearchBreakpointList (Address);

  if (Breakpoint == NULL) {
    return;
  }

  // Add it to the list
  RemoveEntryList (&Breakpoint->Link);

  // Restore the original instruction
  *(UINT32 *)Address = Breakpoint->Instruction;
  InvalidateInstructionCacheRange ((VOID *)Address, 4);

  //DEBUG((EFI_D_ERROR, "ClearBreakpoint at 0x%08x (was: 0x%08x is:0x%08x)\n", Address, GDB_ARM_BKPT, *(UINT32 *)Address));

  FreePool (Breakpoint);
}

VOID
EFIAPI
InsertBreakPoint (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN  CHAR8              *PacketData
  )
{
  UINTN Type;
  UINTN Address;
  UINTN Length;
  UINTN ErrorCode;

  ErrorCode = ParseBreakpointPacket (PacketData, &Type, &Address, &Length);
  if (ErrorCode > 0) {
    SendError ((UINT8)ErrorCode);
    return;
  }

  switch (Type) {
    case 0:   //Software breakpoint
      break;

    default  :
      DEBUG((EFI_D_ERROR, "Insert breakpoint default: %x\n", Type));
      SendError (GDB_EINVALIDBRKPOINTTYPE);
      return;
  }

  SetBreakpoint (Address);

  SendSuccess ();
}

VOID
EFIAPI
RemoveBreakPoint (
  IN  EFI_SYSTEM_CONTEXT  SystemContext,
  IN  CHAR8               *PacketData
  )
{
  UINTN      Type;
  UINTN      Address;
  UINTN      Length;
  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
      break;

    default:
      SendError (GDB_EINVALIDBRKPOINTTYPE);
      return;
  }

  ClearBreakpoint (Address);

  SendSuccess ();
}

VOID
InitializeProcessor (
  VOID
  )
{
  // Initialize breakpoint list
  InitializeListHead (&BreakpointList);
}

BOOLEAN
ValidateAddress (
  IN  VOID  *Address
  )
{
  if ((UINT32)Address < 0x80000000) {
    return FALSE;
  } else {
    return TRUE;
  }
}

BOOLEAN
ValidateException (
  IN  EFI_EXCEPTION_TYPE    ExceptionType,
  IN OUT EFI_SYSTEM_CONTEXT SystemContext
  )
{
  UINT32  ExceptionAddress;
  UINT32  Instruction;

  // Is it a debugger SWI?
  ExceptionAddress = SystemContext.SystemContextArm->PC -= 4;
  Instruction      = *(UINT32 *)ExceptionAddress;
  if (Instruction != GDB_ARM_BKPT) {
    return FALSE;
  }

  // Special for SWI-based exception handling.  SWI sets up the context
  // to return to the instruction following the SWI instruction - NOT what we want
  // for a debugger!
  SystemContext.SystemContextArm->PC = ExceptionAddress;

  return TRUE;
}