llvm/llvm/lib/Target/X86/X86LoadValueInjectionRetHardening.cpp

//===-- X86LoadValueInjectionRetHardening.cpp - LVI RET hardening for x86 --==//
//
// 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
//
//===----------------------------------------------------------------------===//
///
/// Description: Replaces every `ret` instruction with the sequence:
/// ```
/// pop <scratch-reg>
/// lfence
/// jmp *<scratch-reg>
/// ```
/// where `<scratch-reg>` is some available scratch register, according to the
/// calling convention of the function being mitigated.
///
//===----------------------------------------------------------------------===//

#include "X86.h"
#include "X86InstrBuilder.h"
#include "X86Subtarget.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/IR/Function.h"
#include "llvm/Support/Debug.h"

usingnamespacellvm;

#define PASS_KEY …
#define DEBUG_TYPE …

STATISTIC(NumFences, "Number of LFENCEs inserted for LVI mitigation");
STATISTIC(NumFunctionsConsidered, "Number of functions analyzed");
STATISTIC(NumFunctionsMitigated, "Number of functions for which mitigations "
                                 "were deployed");

namespace {

class X86LoadValueInjectionRetHardeningPass : public MachineFunctionPass { … };

} // end anonymous namespace

char X86LoadValueInjectionRetHardeningPass::ID = …;

bool X86LoadValueInjectionRetHardeningPass::runOnMachineFunction(
    MachineFunction &MF) { … }

INITIALIZE_PASS(…)

FunctionPass *llvm::createX86LoadValueInjectionRetHardeningPass() { … }