gdb: Fix single-stepping of branch instructions

This commit is contained in:
Coxxs 2025-06-23 07:05:45 +08:00
parent c4abaa6cf2
commit b1c1ad54e8

View file

@ -195,6 +195,22 @@ namespace ARMeilleure.Translation
private ulong Step(State.ExecutionContext context, ulong address) private ulong Step(State.ExecutionContext context, ulong address)
{ {
try
{
OpCode opCode = Decoder.DecodeOpCode(Memory, address, context.ExecutionMode);
// For branch instructions during single-stepping, we handle them manually
// func.Execute() will sometimes execute the entire function call, which is not what we want
if (opCode.Instruction.Name is InstName.Bl or InstName.Blr or InstName.Blx or InstName.Br)
{
return ExecuteBranchInstructionForStepping(context, address, opCode);
}
}
catch
{
// ignore
}
TranslatedFunction func = Translate(address, context.ExecutionMode, highCq: false, singleStep: true); TranslatedFunction func = Translate(address, context.ExecutionMode, highCq: false, singleStep: true);
address = func.Execute(Stubs.ContextWrapper, context); address = func.Execute(Stubs.ContextWrapper, context);
@ -204,6 +220,94 @@ namespace ARMeilleure.Translation
return address; return address;
} }
private static ulong ExecuteBranchInstructionForStepping(State.ExecutionContext context, ulong address, OpCode opCode)
{
switch (opCode.Instruction.Name)
{
case InstName.Bl:
if (opCode is IOpCodeBImm opBImm)
{
// Set link register
if (context.ExecutionMode == ExecutionMode.Aarch64)
{
context.SetX(30, address + (ulong)opCode.OpCodeSizeInBytes); // LR = X30
}
else
{
// For ARM32, need to set the appropriate return address
uint returnAddr = opCode is OpCode32 op32 && op32.IsThumb
? (uint)address + (uint)opCode.OpCodeSizeInBytes | 1u // Thumb bit set
: (uint)address + (uint)opCode.OpCodeSizeInBytes;
context.SetX(14, returnAddr); // LR = R14
}
return (ulong)opBImm.Immediate;
}
break;
case InstName.Blr:
if (opCode is OpCodeBReg opBReg)
{
// Set link register
if (context.ExecutionMode == ExecutionMode.Aarch64)
{
context.SetX(30, address + (ulong)opCode.OpCodeSizeInBytes); // LR = X30
}
else
{
uint returnAddr = opCode is OpCode32 op32 && op32.IsThumb
? (uint)address + (uint)opCode.OpCodeSizeInBytes | 1u // Thumb bit set
: (uint)address + (uint)opCode.OpCodeSizeInBytes;
context.SetX(14, returnAddr); // LR = R14
}
return context.GetX(opBReg.Rn);
}
break;
case InstName.Blx:
if (opCode is IOpCodeBImm opBlxImm)
{
// Handle mode switching for BLX
if (opCode is OpCode32 op32)
{
uint returnAddr = op32.IsThumb
? (uint)address + (uint)opCode.OpCodeSizeInBytes | 1u
: (uint)address + (uint)opCode.OpCodeSizeInBytes;
context.SetX(14, returnAddr);
// BLX switches between ARM and Thumb modes
context.SetPstateFlag(PState.TFlag, !op32.IsThumb);
}
return (ulong)opBlxImm.Immediate;
}
else if (opCode is IOpCode32BReg opBlxReg)
{
if (opCode is OpCode32 op32)
{
uint returnAddr = op32.IsThumb
? (uint)address + (uint)opCode.OpCodeSizeInBytes | 1u
: (uint)address + (uint)opCode.OpCodeSizeInBytes;
context.SetX(14, returnAddr);
// For BLX register, the target address determines the mode
ulong targetAddr = context.GetX(opBlxReg.Rm);
context.SetPstateFlag(PState.TFlag, (targetAddr & 1) != 0);
return targetAddr & ~1UL; // Clear the Thumb bit for the actual address
}
}
break;
case InstName.Br:
if (opCode is OpCodeBReg opBr)
{
// BR doesn't set link register, just branches to the target
return context.GetX(opBr.Rn);
}
break;
}
throw new InvalidOperationException($"Unhandled branch instruction: {opCode.Instruction.Name}");
}
internal TranslatedFunction GetOrTranslate(ulong address, ExecutionMode mode) internal TranslatedFunction GetOrTranslate(ulong address, ExecutionMode mode)
{ {
if (!Functions.TryGetValue(address, out TranslatedFunction func)) if (!Functions.TryGetValue(address, out TranslatedFunction func))