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cpu_patches: Simplify and remove some restrictions on macOS. (#2591)

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squidbus 2025-03-04 03:25:51 -08:00 • committed by GitHub
parent 7bef4a5c70
commit 3a9633f553
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1 changed files with 24 additions and 26 deletions
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50
src/core/cpu_patches.cpp
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@ -180,22 +180,36 @@ static void RestoreStack(Xbyak::CodeGenerator& c) {
c.mov(rsp, qword[reinterpret_cast<void*>(stack_pointer_slot * sizeof(void*))]);
}
/// Validates that the dst register is supported given the SaveStack/RestoreStack implementation.
static void ValidateDst(const Xbyak::Reg& dst) {
// No restrictions.
}
#else
// These utilities are not implemented as we can't save anything to thread local storage without
// temporary registers.
void InitializeThreadPatchStack() {
// No-op
}
// NOTE: Since stack pointer here is subtracted through safe zone and not saved anywhere,
// it must not be modified during the instruction. Otherwise, we will not be able to find
// and load registers back from where they were saved. Thus, a limitation is placed on
// instructions, that they must not use the stack pointer register as a destination.
/// Saves the stack pointer to thread local storage and loads the patch stack.
static void SaveStack(Xbyak::CodeGenerator& c) {
UNIMPLEMENTED();
c.lea(rsp, ptr[rsp - 128]); // red zone
}
/// Restores the stack pointer from thread local storage.
static void RestoreStack(Xbyak::CodeGenerator& c) {
UNIMPLEMENTED();
c.lea(rsp, ptr[rsp + 128]); // red zone
}
/// Validates that the dst register is supported given the SaveStack/RestoreStack implementation.
static void ValidateDst(const Xbyak::Reg& dst) {
// Stack pointer is not preserved, so it can't be used as a dst.
ASSERT_MSG(dst.getIdx() != rsp.getIdx(), "Stack pointer not supported as destination.");
}
#endif
@ -204,37 +218,21 @@ static void RestoreStack(Xbyak::CodeGenerator& c) {
static void SaveRegisters(Xbyak::CodeGenerator& c, const std::initializer_list<Xbyak::Reg> regs) {
// Uses a more robust solution for saving registers on MacOS to avoid potential stack corruption
// if games decide to not follow the ABI and use the red zone.
#ifdef __APPLE__
SaveStack(c);
#else
c.lea(rsp, ptr[rsp - 128]); // red zone
#endif
for (const auto& reg : regs) {
c.push(reg.cvt64());
}
#ifdef __APPLE__
RestoreStack(c);
#else
c.lea(rsp, ptr[rsp + 128]);
#endif
}
/// Switches to the patch stack, restores registers, and restores the original stack.
static void RestoreRegisters(Xbyak::CodeGenerator& c,
const std::initializer_list<Xbyak::Reg> regs) {
#ifdef __APPLE__
SaveStack(c);
#else
c.lea(rsp, ptr[rsp - 128]); // red zone
#endif
for (const auto& reg : regs) {
c.pop(reg.cvt64());
}
#ifdef __APPLE__
RestoreStack(c);
#else
c.lea(rsp, ptr[rsp + 128]);
#endif
}
/// Switches to the patch stack and stores all registers.
@ -279,7 +277,7 @@ static void GenerateANDN(const ZydisDecodedOperand* operands, Xbyak::CodeGenerat
const auto dst = ZydisToXbyakRegisterOperand(operands[0]);
const auto src1 = ZydisToXbyakRegisterOperand(operands[1]);
const auto src2 = ZydisToXbyakOperand(operands[2]);
ASSERT_MSG(dst.getIdx() != rsp.getIdx(), "ANDN overwriting the stack pointer");
ValidateDst(dst);
// Check if src2 is a memory operand or a register different to dst.
// In those cases, we don't need to use a temporary register and are free to modify dst.
@ -318,7 +316,7 @@ static void GenerateBEXTR(const ZydisDecodedOperand* operands, Xbyak::CodeGenera
const auto dst = ZydisToXbyakRegisterOperand(operands[0]);
const auto src = ZydisToXbyakOperand(operands[1]);
const auto start_len = ZydisToXbyakRegisterOperand(operands[2]);
ASSERT_MSG(dst.getIdx() != rsp.getIdx(), "BEXTR overwriting the stack pointer");
ValidateDst(dst);
const Xbyak::Reg32e shift(Xbyak::Operand::RCX, static_cast<int>(start_len.getBit()));
const auto scratch1 =
@ -356,7 +354,7 @@ static void GenerateBEXTR(const ZydisDecodedOperand* operands, Xbyak::CodeGenera
static void GenerateBLSI(const ZydisDecodedOperand* operands, Xbyak::CodeGenerator& c) {
const auto dst = ZydisToXbyakRegisterOperand(operands[0]);
const auto src = ZydisToXbyakOperand(operands[1]);
ASSERT_MSG(dst.getIdx() != rsp.getIdx(), "BLSI overwriting the stack pointer");
ValidateDst(dst);
const auto scratch = AllocateScratchRegister({&dst, src.get()}, dst.getBit());
@ -386,7 +384,7 @@ static void GenerateBLSI(const ZydisDecodedOperand* operands, Xbyak::CodeGenerat
static void GenerateBLSMSK(const ZydisDecodedOperand* operands, Xbyak::CodeGenerator& c) {
const auto dst = ZydisToXbyakRegisterOperand(operands[0]);
const auto src = ZydisToXbyakOperand(operands[1]);
ASSERT_MSG(dst.getIdx() != rsp.getIdx(), "BLSMSK overwriting the stack pointer");
ValidateDst(dst);
const auto scratch = AllocateScratchRegister({&dst, src.get()}, dst.getBit());
@ -418,7 +416,7 @@ static void GenerateBLSMSK(const ZydisDecodedOperand* operands, Xbyak::CodeGener
static void GenerateTZCNT(const ZydisDecodedOperand* operands, Xbyak::CodeGenerator& c) {
const auto dst = ZydisToXbyakRegisterOperand(operands[0]);
const auto src = ZydisToXbyakOperand(operands[1]);
ASSERT_MSG(dst.getIdx() != rsp.getIdx(), "TZCNT overwriting the stack pointer");
ValidateDst(dst);
Xbyak::Label src_zero, end;
@ -445,7 +443,7 @@ static void GenerateTZCNT(const ZydisDecodedOperand* operands, Xbyak::CodeGenera
static void GenerateBLSR(const ZydisDecodedOperand* operands, Xbyak::CodeGenerator& c) {
const auto dst = ZydisToXbyakRegisterOperand(operands[0]);
const auto src = ZydisToXbyakOperand(operands[1]);
ASSERT_MSG(dst.getIdx() != rsp.getIdx(), "BLSR overwriting the stack pointer");
ValidateDst(dst);
const auto scratch = AllocateScratchRegister({&dst, src.get()}, dst.getBit());