X86ReturnThunks.cpp File Reference

Pass that replaces ret instructions with a jmp to __x86_return_thunk. More...

#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"

Go to the source code of this file.

Macros
#define	PASS_KEY   "x86-return-thunks"
#define	DEBUG_TYPE   PASS_KEY

Functions
static bool	runX86ReturnThunks (MachineFunction &MF)
	INITIALIZE_PASS (X86ReturnThunksLegacy, PASS_KEY, "X86 Return Thunks", false, false) FunctionPass *llvm

Variables
constexpr StringRef	X86ReturnThunksPassName = "X86 Return Thunks"

Detailed Description

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.

Definition in file X86ReturnThunks.cpp.

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   PASS_KEY

Definition at line 45 of file X86ReturnThunks.cpp.

PASS_KEY

#define PASS_KEY   "x86-return-thunks"

Definition at line 44 of file X86ReturnThunks.cpp.

Function Documentation

INITIALIZE_PASS()

INITIALIZE_PASS	(	X86ReturnThunksLegacy	,
		PASS_KEY	,
		"X86 Return Thunks"	,
		false	,
		false	)

Definition at line 111 of file X86ReturnThunks.cpp.

References llvm::createX86ReturnThunksLegacyPass(), and PASS_KEY.

runX86ReturnThunks()

bool runX86ReturnThunks ( MachineFunction & MF )

static

Definition at line 60 of file X86ReturnThunks.cpp.

References llvm::MachineInstrBuilder::addExternalSymbol(), llvm::BuildMI(), llvm::StringRef::data(), llvm::dbgs(), llvm::MachineInstr::eraseFromParent(), llvm::MachineFunction::getFunction(), llvm::Module::getModuleFlag(), llvm::Value::getName(), llvm::GlobalValue::getParent(), llvm::MachineFunction::getSubtarget(), llvm::Function::hasFnAttribute(), LLVM_DEBUG, MBB, Modified, llvm::SmallVectorTemplateBase< T, bool >::push_back(), and X86ReturnThunksPassName.

Referenced by llvm::X86ReturnThunksPass::run().

Variable Documentation

X86ReturnThunksPassName

StringRef X86ReturnThunksPassName = "X86 Return Thunks"

constexpr

Definition at line 47 of file X86ReturnThunks.cpp.

Referenced by runX86ReturnThunks().