llvm/llvm/lib/Target/X86/X86ReturnThunks.cpp

//==- X86ReturnThunks.cpp - Replace rets with thunks or inline thunks --=//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
/// \file
///
/// Pass that replaces ret instructions with a jmp to __x86_return_thunk.
///
/// This corresponds to -mfunction-return=thunk-extern or
/// __attribute__((function_return("thunk-extern").
///
/// This pass is a minimal implementation necessary to help mitigate
/// RetBleed for the Linux kernel.
///
/// Should support for thunk or thunk-inline be necessary in the future, then
/// this pass should be combined with x86-retpoline-thunks which already has
/// machinery to emit thunks. Until then, YAGNI.
///
/// This pass is very similar to x86-lvi-ret.
///
//===----------------------------------------------------------------------===//

#include "X86.h"
#include "X86InstrInfo.h"
#include "X86Subtarget.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/MCInstrDesc.h"
#include "llvm/Support/Debug.h"
#include "llvm/TargetParser/Triple.h"

usingnamespacellvm;

#define PASS_KEY …
#define DEBUG_TYPE …

namespace {
struct X86ReturnThunks final : public MachineFunctionPass { … };
} // namespace

char X86ReturnThunks::ID = …;

bool X86ReturnThunks::runOnMachineFunction(MachineFunction &MF) { … }

INITIALIZE_PASS(…)

FunctionPass *llvm::createX86ReturnThunksPass() { … }