/* == Patch Function ==
*
* First a function stub is generated containing:
* 1. Opcodes between Instruction.PC and "newAddress"
* 2. a jmp to "newAddress".
*
* Then these functions look at the original JMP target and look for jumps back to
* the end of the instruction.
*
* Patches are then generated that convert those jumps back to jumps to the location of
* function stub.
*
* Patches are added to patch.Patches.
*/
private void PatchReturnAddresses(JumpDetails jumpDetails, FunctionPatch patch, long newAddress)
{
long originalJmpTarget = jumpDetails.JumpOpcodeTarget;
GetSearchRange(ref originalJmpTarget, out long searchLength);
/* Get original opcodes after original JMP instruction. */
IntPtr startRemainingOpcodes = (IntPtr)jumpDetails.JumpOpcodeEnd;
int lengthRemainingOpcodes = (int)(newAddress - (long)startRemainingOpcodes);
CurrentProcess.ReadRaw(startRemainingOpcodes, out byte[] remainingInstructions, lengthRemainingOpcodes);
/* Build function stub + patches. */
// Must guarantee relative jumps to be patches can reach our new prologue
// as such must get range of search first before creating stub.
long maxDisplacement = Int32.MaxValue - searchLength;
IntPtr newOriginalPrologue = Utilities.InsertJump(remainingInstructions, Is64Bit(), newAddress, originalJmpTarget, maxDisplacement);
var patches = PatchJumpTargets(new AddressRange(originalJmpTarget, originalJmpTarget + searchLength),
new AddressRange((long)startRemainingOpcodes, newAddress), (long)newOriginalPrologue);
patch.Patches.AddRange(patches);
}
/* == Patch Function ==
*
* First a function stub is generated containing:
* 1. Opcodes between Instruction.PC and "newAddress"
* 2. a jmp to "newAddress".
*
* Then these functions look at the original JMP target and look for jumps back to
* the end of the instruction.
*
* Patches are then generated that convert those jumps back to jumps to the location of
* function stub.
*
* Patches are added to patch.Patches.
*/
private void PatchReturnAddresses(JumpDetails jumpDetails, FunctionPatch patch, long newAddress)
{
long originalJmpTarget = jumpDetails.JumpOpcodeTarget;
long initialSearchPointer = originalJmpTarget;
GetSearchRange(ref initialSearchPointer, out long searchLength);
/* Get original opcodes after original JMP instruction. */
IntPtr startRemainingOpcodes = (IntPtr)jumpDetails.JumpOpcodeEnd;
int lengthRemainingOpcodes = (int)(newAddress - (long)startRemainingOpcodes);
var remainingInstructions = TryReadFromMemory(startRemainingOpcodes, lengthRemainingOpcodes);
/* Build function stub + patches. */
// Must guarantee relative jumps to be patches can reach our new prologue
// as such must get range of search first before creating stub.
long maxDisplacement = Int32.MaxValue - searchLength;
IntPtr newOriginalPrologue = Utilities.InsertJump(remainingInstructions, Is64Bit(), newAddress, originalJmpTarget, maxDisplacement);
// Catch all return addresses in page range.
var pageRange = new AddressRange(initialSearchPointer, initialSearchPointer + searchLength);
var jumpTargetRange = new AddressRange((long)startRemainingOpcodes, newAddress);
patch.Patches = PatchJumpTargets(pageRange, originalJmpTarget, jumpTargetRange, newOriginalPrologue);
}
