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llvm-project/llvm/lib/Target/X86/AsmParser/X86AsmInstrumentation.cpp

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//===-- X86AsmInstrumentation.cpp - Instrument X86 inline assembly --------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "X86AsmInstrumentation.h"
#include "MCTargetDesc/X86MCTargetDesc.h"
#include "X86Operand.h"
#include "llvm/ADT/Triple.h"
#include "llvm/ADT/Twine.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCDwarf.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCInstBuilder.h"
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/MC/MCParser/MCParsedAsmOperand.h"
#include "llvm/MC/MCParser/MCTargetAsmParser.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/MCTargetOptions.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/SMLoc.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <limits>
#include <memory>
#include <vector>
// Following comment describes how assembly instrumentation works.
// Currently we have only AddressSanitizer instrumentation, but we're
// planning to implement MemorySanitizer for inline assembly too. If
// you're not familiar with AddressSanitizer algorithm, please, read
// https://github.com/google/sanitizers/wiki/AddressSanitizerAlgorithm
//
// When inline assembly is parsed by an instance of X86AsmParser, all
// instructions are emitted via EmitInstruction method. That's the
// place where X86AsmInstrumentation analyzes an instruction and
// decides, whether the instruction should be emitted as is or
// instrumentation is required. The latter case happens when an
// instruction reads from or writes to memory. Now instruction opcode
// is explicitly checked, and if an instruction has a memory operand
// (for instance, movq (%rsi, %rcx, 8), %rax) - it should be
// instrumented. There're also exist instructions that modify
// memory but don't have an explicit memory operands, for instance,
// movs.
//
// Let's consider at first 8-byte memory accesses when an instruction
// has an explicit memory operand. In this case we need two registers -
// AddressReg to compute address of a memory cells which are accessed
// and ShadowReg to compute corresponding shadow address. So, we need
// to spill both registers before instrumentation code and restore them
// after instrumentation. Thus, in general, instrumentation code will
// look like this:
// PUSHF # Store flags, otherwise they will be overwritten
// PUSH AddressReg # spill AddressReg
// PUSH ShadowReg # spill ShadowReg
// LEA MemOp, AddressReg # compute address of the memory operand
// MOV AddressReg, ShadowReg
// SHR ShadowReg, 3
// # ShadowOffset(AddressReg >> 3) contains address of a shadow
// # corresponding to MemOp.
// CMP ShadowOffset(ShadowReg), 0 # test shadow value
// JZ .Done # when shadow equals to zero, everything is fine
// MOV AddressReg, RDI
// # Call __asan_report function with AddressReg as an argument
// CALL __asan_report
// .Done:
// POP ShadowReg # Restore ShadowReg
// POP AddressReg # Restore AddressReg
// POPF # Restore flags
//
// Memory accesses with different size (1-, 2-, 4- and 16-byte) are
// handled in a similar manner, but small memory accesses (less than 8
// byte) require an additional ScratchReg, which is used for shadow value.
//
// If, suppose, we're instrumenting an instruction like movs, only
// contents of RDI, RDI + AccessSize * RCX, RSI, RSI + AccessSize *
// RCX are checked. In this case there're no need to spill and restore
// AddressReg , ShadowReg or flags four times, they're saved on stack
// just once, before instrumentation of these four addresses, and restored
// at the end of the instrumentation.
//
// There exist several things which complicate this simple algorithm.
// * Instrumented memory operand can have RSP as a base or an index
// register. So we need to add a constant offset before computation
// of memory address, since flags, AddressReg, ShadowReg, etc. were
// already stored on stack and RSP was modified.
// * Debug info (usually, DWARF) should be adjusted, because sometimes
// RSP is used as a frame register. So, we need to select some
// register as a frame register and temprorary override current CFA
// register.
using namespace llvm;
static cl::opt<bool> ClAsanInstrumentAssembly(
"asan-instrument-assembly",
cl::desc("instrument assembly with AddressSanitizer checks"), cl::Hidden,
cl::init(false));
static const int64_t MinAllowedDisplacement =
std::numeric_limits<int32_t>::min();
static const int64_t MaxAllowedDisplacement =
std::numeric_limits<int32_t>::max();
static int64_t ApplyDisplacementBounds(int64_t Displacement) {
return std::max(std::min(MaxAllowedDisplacement, Displacement),
MinAllowedDisplacement);
}
static void CheckDisplacementBounds(int64_t Displacement) {
assert(Displacement >= MinAllowedDisplacement &&
Displacement <= MaxAllowedDisplacement);
}
static bool IsStackReg(unsigned Reg) {
return Reg == X86::RSP || Reg == X86::ESP;
}
static bool IsSmallMemAccess(unsigned AccessSize) { return AccessSize < 8; }
namespace {
class X86AddressSanitizer : public X86AsmInstrumentation {
public:
struct RegisterContext {
private:
enum RegOffset {
REG_OFFSET_ADDRESS = 0,
REG_OFFSET_SHADOW,
REG_OFFSET_SCRATCH
};
public:
RegisterContext(unsigned AddressReg, unsigned ShadowReg,
unsigned ScratchReg) {
BusyRegs.push_back(convReg(AddressReg, 64));
BusyRegs.push_back(convReg(ShadowReg, 64));
BusyRegs.push_back(convReg(ScratchReg, 64));
}
unsigned AddressReg(unsigned Size) const {
return convReg(BusyRegs[REG_OFFSET_ADDRESS], Size);
}
unsigned ShadowReg(unsigned Size) const {
return convReg(BusyRegs[REG_OFFSET_SHADOW], Size);
}
unsigned ScratchReg(unsigned Size) const {
return convReg(BusyRegs[REG_OFFSET_SCRATCH], Size);
}
void AddBusyReg(unsigned Reg) {
if (Reg != X86::NoRegister)
BusyRegs.push_back(convReg(Reg, 64));
}
void AddBusyRegs(const X86Operand &Op) {
AddBusyReg(Op.getMemBaseReg());
AddBusyReg(Op.getMemIndexReg());
}
unsigned ChooseFrameReg(unsigned Size) const {
static const MCPhysReg Candidates[] = { X86::RBP, X86::RAX, X86::RBX,
X86::RCX, X86::RDX, X86::RDI,
X86::RSI };
for (unsigned Reg : Candidates) {
if (!std::count(BusyRegs.begin(), BusyRegs.end(), Reg))
return convReg(Reg, Size);
}
return X86::NoRegister;
}
private:
unsigned convReg(unsigned Reg, unsigned Size) const {
return Reg == X86::NoRegister ? Reg : getX86SubSuperRegister(Reg, Size);
}
std::vector<unsigned> BusyRegs;
};
X86AddressSanitizer(const MCSubtargetInfo *&STI)
: X86AsmInstrumentation(STI), RepPrefix(false), OrigSPOffset(0) {}
~X86AddressSanitizer() override = default;
// X86AsmInstrumentation implementation:
void InstrumentAndEmitInstruction(const MCInst &Inst, OperandVector &Operands,
MCContext &Ctx, const MCInstrInfo &MII,
MCStreamer &Out,
/* unused */ bool) override {
InstrumentMOVS(Inst, Operands, Ctx, MII, Out);
if (RepPrefix)
EmitInstruction(Out, MCInstBuilder(X86::REP_PREFIX));
InstrumentMOV(Inst, Operands, Ctx, MII, Out);
RepPrefix = (Inst.getOpcode() == X86::REP_PREFIX);
if (!RepPrefix)
EmitInstruction(Out, Inst);
}
// Adjusts up stack and saves all registers used in instrumentation.
virtual void InstrumentMemOperandPrologue(const RegisterContext &RegCtx,
MCContext &Ctx,
MCStreamer &Out) = 0;
// Restores all registers used in instrumentation and adjusts stack.
virtual void InstrumentMemOperandEpilogue(const RegisterContext &RegCtx,
MCContext &Ctx,
MCStreamer &Out) = 0;
virtual void InstrumentMemOperandSmall(X86Operand &Op, unsigned AccessSize,
bool IsWrite,
const RegisterContext &RegCtx,
MCContext &Ctx, MCStreamer &Out) = 0;
virtual void InstrumentMemOperandLarge(X86Operand &Op, unsigned AccessSize,
bool IsWrite,
const RegisterContext &RegCtx,
MCContext &Ctx, MCStreamer &Out) = 0;
virtual void InstrumentMOVSImpl(unsigned AccessSize, MCContext &Ctx,
MCStreamer &Out) = 0;
void InstrumentMemOperand(X86Operand &Op, unsigned AccessSize, bool IsWrite,
const RegisterContext &RegCtx, MCContext &Ctx,
MCStreamer &Out);
void InstrumentMOVSBase(unsigned DstReg, unsigned SrcReg, unsigned CntReg,
unsigned AccessSize, MCContext &Ctx, MCStreamer &Out);
void InstrumentMOVS(const MCInst &Inst, OperandVector &Operands,
MCContext &Ctx, const MCInstrInfo &MII, MCStreamer &Out);
void InstrumentMOV(const MCInst &Inst, OperandVector &Operands,
MCContext &Ctx, const MCInstrInfo &MII, MCStreamer &Out);
protected:
void EmitLabel(MCStreamer &Out, MCSymbol *Label) { Out.EmitLabel(Label); }
void EmitLEA(X86Operand &Op, unsigned Size, unsigned Reg, MCStreamer &Out) {
assert(Size == 32 || Size == 64);
MCInst Inst;
Inst.setOpcode(Size == 32 ? X86::LEA32r : X86::LEA64r);
Inst.addOperand(MCOperand::createReg(getX86SubSuperRegister(Reg, Size)));
Op.addMemOperands(Inst, 5);
EmitInstruction(Out, Inst);
}
void ComputeMemOperandAddress(X86Operand &Op, unsigned Size,
unsigned Reg, MCContext &Ctx, MCStreamer &Out);
// Creates new memory operand with Displacement added to an original
// displacement. Residue will contain a residue which could happen when the
// total displacement exceeds 32-bit limitation.
std::unique_ptr<X86Operand> AddDisplacement(X86Operand &Op,
int64_t Displacement,
MCContext &Ctx, int64_t *Residue);
bool is64BitMode() const {
return STI->getFeatureBits()[X86::Mode64Bit];
}
bool is32BitMode() const {
return STI->getFeatureBits()[X86::Mode32Bit];
}
bool is16BitMode() const {
return STI->getFeatureBits()[X86::Mode16Bit];
}
unsigned getPointerWidth() {
if (is16BitMode()) return 16;
if (is32BitMode()) return 32;
if (is64BitMode()) return 64;
llvm_unreachable("invalid mode");
}
// True when previous instruction was actually REP prefix.
bool RepPrefix;
// Offset from the original SP register.
int64_t OrigSPOffset;
};
void X86AddressSanitizer::InstrumentMemOperand(
X86Operand &Op, unsigned AccessSize, bool IsWrite,
const RegisterContext &RegCtx, MCContext &Ctx, MCStreamer &Out) {
assert(Op.isMem() && "Op should be a memory operand.");
assert((AccessSize & (AccessSize - 1)) == 0 && AccessSize <= 16 &&
"AccessSize should be a power of two, less or equal than 16.");
// FIXME: take into account load/store alignment.
if (IsSmallMemAccess(AccessSize))
InstrumentMemOperandSmall(Op, AccessSize, IsWrite, RegCtx, Ctx, Out);
else
InstrumentMemOperandLarge(Op, AccessSize, IsWrite, RegCtx, Ctx, Out);
}
void X86AddressSanitizer::InstrumentMOVSBase(unsigned DstReg, unsigned SrcReg,
unsigned CntReg,
unsigned AccessSize,
MCContext &Ctx, MCStreamer &Out) {
// FIXME: check whole ranges [DstReg .. DstReg + AccessSize * (CntReg - 1)]
// and [SrcReg .. SrcReg + AccessSize * (CntReg - 1)].
RegisterContext RegCtx(X86::RDX /* AddressReg */, X86::RAX /* ShadowReg */,
IsSmallMemAccess(AccessSize)
? X86::RBX
: X86::NoRegister /* ScratchReg */);
RegCtx.AddBusyReg(DstReg);
RegCtx.AddBusyReg(SrcReg);
RegCtx.AddBusyReg(CntReg);
InstrumentMemOperandPrologue(RegCtx, Ctx, Out);
// Test (%SrcReg)
{
const MCExpr *Disp = MCConstantExpr::create(0, Ctx);
std::unique_ptr<X86Operand> Op(X86Operand::CreateMem(
getPointerWidth(), 0, Disp, SrcReg, 0, AccessSize, SMLoc(), SMLoc()));
InstrumentMemOperand(*Op, AccessSize, false /* IsWrite */, RegCtx, Ctx,
Out);
}
// Test -1(%SrcReg, %CntReg, AccessSize)
{
const MCExpr *Disp = MCConstantExpr::create(-1, Ctx);
std::unique_ptr<X86Operand> Op(X86Operand::CreateMem(
getPointerWidth(), 0, Disp, SrcReg, CntReg, AccessSize, SMLoc(),
SMLoc()));
InstrumentMemOperand(*Op, AccessSize, false /* IsWrite */, RegCtx, Ctx,
Out);
}
// Test (%DstReg)
{
const MCExpr *Disp = MCConstantExpr::create(0, Ctx);
std::unique_ptr<X86Operand> Op(X86Operand::CreateMem(
getPointerWidth(), 0, Disp, DstReg, 0, AccessSize, SMLoc(), SMLoc()));
InstrumentMemOperand(*Op, AccessSize, true /* IsWrite */, RegCtx, Ctx, Out);
}
// Test -1(%DstReg, %CntReg, AccessSize)
{
const MCExpr *Disp = MCConstantExpr::create(-1, Ctx);
std::unique_ptr<X86Operand> Op(X86Operand::CreateMem(
getPointerWidth(), 0, Disp, DstReg, CntReg, AccessSize, SMLoc(),
SMLoc()));
InstrumentMemOperand(*Op, AccessSize, true /* IsWrite */, RegCtx, Ctx, Out);
}
InstrumentMemOperandEpilogue(RegCtx, Ctx, Out);
}
void X86AddressSanitizer::InstrumentMOVS(const MCInst &Inst,
OperandVector &Operands,
MCContext &Ctx, const MCInstrInfo &MII,
MCStreamer &Out) {
// Access size in bytes.
unsigned AccessSize = 0;
switch (Inst.getOpcode()) {
case X86::MOVSB:
AccessSize = 1;
break;
case X86::MOVSW:
AccessSize = 2;
break;
case X86::MOVSL:
AccessSize = 4;
break;
case X86::MOVSQ:
AccessSize = 8;
break;
default:
return;
}
InstrumentMOVSImpl(AccessSize, Ctx, Out);
}
void X86AddressSanitizer::InstrumentMOV(const MCInst &Inst,
OperandVector &Operands, MCContext &Ctx,
const MCInstrInfo &MII,
MCStreamer &Out) {
// Access size in bytes.
unsigned AccessSize = 0;
switch (Inst.getOpcode()) {
case X86::MOV8mi:
case X86::MOV8mr:
case X86::MOV8rm:
AccessSize = 1;
break;
case X86::MOV16mi:
case X86::MOV16mr:
case X86::MOV16rm:
AccessSize = 2;
break;
case X86::MOV32mi:
case X86::MOV32mr:
case X86::MOV32rm:
AccessSize = 4;
break;
case X86::MOV64mi32:
case X86::MOV64mr:
case X86::MOV64rm:
AccessSize = 8;
break;
case X86::MOVAPDmr:
case X86::MOVAPSmr:
case X86::MOVAPDrm:
case X86::MOVAPSrm:
AccessSize = 16;
break;
default:
return;
}
const bool IsWrite = MII.get(Inst.getOpcode()).mayStore();
for (unsigned Ix = 0; Ix < Operands.size(); ++Ix) {
assert(Operands[Ix]);
MCParsedAsmOperand &Op = *Operands[Ix];
if (Op.isMem()) {
X86Operand &MemOp = static_cast<X86Operand &>(Op);
RegisterContext RegCtx(
X86::RDI /* AddressReg */, X86::RAX /* ShadowReg */,
IsSmallMemAccess(AccessSize) ? X86::RCX
: X86::NoRegister /* ScratchReg */);
RegCtx.AddBusyRegs(MemOp);
InstrumentMemOperandPrologue(RegCtx, Ctx, Out);
InstrumentMemOperand(MemOp, AccessSize, IsWrite, RegCtx, Ctx, Out);
InstrumentMemOperandEpilogue(RegCtx, Ctx, Out);
}
}
}
void X86AddressSanitizer::ComputeMemOperandAddress(X86Operand &Op,
unsigned Size,
unsigned Reg, MCContext &Ctx,
MCStreamer &Out) {
int64_t Displacement = 0;
if (IsStackReg(Op.getMemBaseReg()))
Displacement -= OrigSPOffset;
if (IsStackReg(Op.getMemIndexReg()))
Displacement -= OrigSPOffset * Op.getMemScale();
assert(Displacement >= 0);
// Emit Op as is.
if (Displacement == 0) {
EmitLEA(Op, Size, Reg, Out);
return;
}
int64_t Residue;
std::unique_ptr<X86Operand> NewOp =
AddDisplacement(Op, Displacement, Ctx, &Residue);
EmitLEA(*NewOp, Size, Reg, Out);
while (Residue != 0) {
const MCConstantExpr *Disp =
MCConstantExpr::create(ApplyDisplacementBounds(Residue), Ctx);
std::unique_ptr<X86Operand> DispOp =
X86Operand::CreateMem(getPointerWidth(), 0, Disp, Reg, 0, 1, SMLoc(),
SMLoc());
EmitLEA(*DispOp, Size, Reg, Out);
Residue -= Disp->getValue();
}
}
std::unique_ptr<X86Operand>
X86AddressSanitizer::AddDisplacement(X86Operand &Op, int64_t Displacement,
MCContext &Ctx, int64_t *Residue) {
assert(Displacement >= 0);
if (Displacement == 0 ||
(Op.getMemDisp() && Op.getMemDisp()->getKind() != MCExpr::Constant)) {
*Residue = Displacement;
return X86Operand::CreateMem(Op.getMemModeSize(), Op.getMemSegReg(),
Op.getMemDisp(), Op.getMemBaseReg(),
Op.getMemIndexReg(), Op.getMemScale(),
SMLoc(), SMLoc());
}
int64_t OrigDisplacement =
static_cast<const MCConstantExpr *>(Op.getMemDisp())->getValue();
CheckDisplacementBounds(OrigDisplacement);
Displacement += OrigDisplacement;
int64_t NewDisplacement = ApplyDisplacementBounds(Displacement);
CheckDisplacementBounds(NewDisplacement);
*Residue = Displacement - NewDisplacement;
const MCExpr *Disp = MCConstantExpr::create(NewDisplacement, Ctx);
return X86Operand::CreateMem(Op.getMemModeSize(), Op.getMemSegReg(), Disp,
Op.getMemBaseReg(), Op.getMemIndexReg(),
Op.getMemScale(), SMLoc(), SMLoc());
}
class X86AddressSanitizer32 : public X86AddressSanitizer {
public:
static const long kShadowOffset = 0x20000000;
X86AddressSanitizer32(const MCSubtargetInfo *&STI)
: X86AddressSanitizer(STI) {}
~X86AddressSanitizer32() override = default;
unsigned GetFrameReg(const MCContext &Ctx, MCStreamer &Out) {
unsigned FrameReg = GetFrameRegGeneric(Ctx, Out);
if (FrameReg == X86::NoRegister)
return FrameReg;
return getX86SubSuperRegister(FrameReg, 32);
}
void SpillReg(MCStreamer &Out, unsigned Reg) {
EmitInstruction(Out, MCInstBuilder(X86::PUSH32r).addReg(Reg));
OrigSPOffset -= 4;
}
void RestoreReg(MCStreamer &Out, unsigned Reg) {
EmitInstruction(Out, MCInstBuilder(X86::POP32r).addReg(Reg));
OrigSPOffset += 4;
}
void StoreFlags(MCStreamer &Out) {
EmitInstruction(Out, MCInstBuilder(X86::PUSHF32));
OrigSPOffset -= 4;
}
void RestoreFlags(MCStreamer &Out) {
EmitInstruction(Out, MCInstBuilder(X86::POPF32));
OrigSPOffset += 4;
}
void InstrumentMemOperandPrologue(const RegisterContext &RegCtx,
MCContext &Ctx,
MCStreamer &Out) override {
unsigned LocalFrameReg = RegCtx.ChooseFrameReg(32);
assert(LocalFrameReg != X86::NoRegister);
const MCRegisterInfo *MRI = Ctx.getRegisterInfo();
unsigned FrameReg = GetFrameReg(Ctx, Out);
if (MRI && FrameReg != X86::NoRegister) {
SpillReg(Out, LocalFrameReg);
if (FrameReg == X86::ESP) {
Out.EmitCFIAdjustCfaOffset(4 /* byte size of the LocalFrameReg */);
Out.EmitCFIRelOffset(
MRI->getDwarfRegNum(LocalFrameReg, true /* IsEH */), 0);
}
EmitInstruction(
Out,
MCInstBuilder(X86::MOV32rr).addReg(LocalFrameReg).addReg(FrameReg));
Out.EmitCFIRememberState();
Out.EmitCFIDefCfaRegister(
MRI->getDwarfRegNum(LocalFrameReg, true /* IsEH */));
}
SpillReg(Out, RegCtx.AddressReg(32));
SpillReg(Out, RegCtx.ShadowReg(32));
if (RegCtx.ScratchReg(32) != X86::NoRegister)
SpillReg(Out, RegCtx.ScratchReg(32));
StoreFlags(Out);
}
void InstrumentMemOperandEpilogue(const RegisterContext &RegCtx,
MCContext &Ctx,
MCStreamer &Out) override {
unsigned LocalFrameReg = RegCtx.ChooseFrameReg(32);
assert(LocalFrameReg != X86::NoRegister);
RestoreFlags(Out);
if (RegCtx.ScratchReg(32) != X86::NoRegister)
RestoreReg(Out, RegCtx.ScratchReg(32));
RestoreReg(Out, RegCtx.ShadowReg(32));
RestoreReg(Out, RegCtx.AddressReg(32));
unsigned FrameReg = GetFrameReg(Ctx, Out);
if (Ctx.getRegisterInfo() && FrameReg != X86::NoRegister) {
RestoreReg(Out, LocalFrameReg);
Out.EmitCFIRestoreState();
if (FrameReg == X86::ESP)
Out.EmitCFIAdjustCfaOffset(-4 /* byte size of the LocalFrameReg */);
}
}
void InstrumentMemOperandSmall(X86Operand &Op, unsigned AccessSize,
bool IsWrite,
const RegisterContext &RegCtx,
MCContext &Ctx,
MCStreamer &Out) override;
void InstrumentMemOperandLarge(X86Operand &Op, unsigned AccessSize,
bool IsWrite,
const RegisterContext &RegCtx,
MCContext &Ctx,
MCStreamer &Out) override;
void InstrumentMOVSImpl(unsigned AccessSize, MCContext &Ctx,
MCStreamer &Out) override;
private:
void EmitCallAsanReport(unsigned AccessSize, bool IsWrite, MCContext &Ctx,
MCStreamer &Out, const RegisterContext &RegCtx) {
EmitInstruction(Out, MCInstBuilder(X86::CLD));
EmitInstruction(Out, MCInstBuilder(X86::MMX_EMMS));
EmitInstruction(Out, MCInstBuilder(X86::AND32ri8)
.addReg(X86::ESP)
.addReg(X86::ESP)
.addImm(-16));
EmitInstruction(
Out, MCInstBuilder(X86::PUSH32r).addReg(RegCtx.AddressReg(32)));
MCSymbol *FnSym = Ctx.getOrCreateSymbol(Twine("__asan_report_") +
(IsWrite ? "store" : "load") +
Twine(AccessSize));
const MCSymbolRefExpr *FnExpr =
MCSymbolRefExpr::create(FnSym, MCSymbolRefExpr::VK_PLT, Ctx);
EmitInstruction(Out, MCInstBuilder(X86::CALLpcrel32).addExpr(FnExpr));
}
};
void X86AddressSanitizer32::InstrumentMemOperandSmall(
X86Operand &Op, unsigned AccessSize, bool IsWrite,
const RegisterContext &RegCtx, MCContext &Ctx, MCStreamer &Out) {
unsigned AddressRegI32 = RegCtx.AddressReg(32);
unsigned ShadowRegI32 = RegCtx.ShadowReg(32);
unsigned ShadowRegI8 = RegCtx.ShadowReg(8);
assert(RegCtx.ScratchReg(32) != X86::NoRegister);
unsigned ScratchRegI32 = RegCtx.ScratchReg(32);
ComputeMemOperandAddress(Op, 32, AddressRegI32, Ctx, Out);
EmitInstruction(Out, MCInstBuilder(X86::MOV32rr).addReg(ShadowRegI32).addReg(
AddressRegI32));
EmitInstruction(Out, MCInstBuilder(X86::SHR32ri)
.addReg(ShadowRegI32)
.addReg(ShadowRegI32)
.addImm(3));
{
MCInst Inst;
Inst.setOpcode(X86::MOV8rm);
Inst.addOperand(MCOperand::createReg(ShadowRegI8));
const MCExpr *Disp = MCConstantExpr::create(kShadowOffset, Ctx);
std::unique_ptr<X86Operand> Op(
X86Operand::CreateMem(getPointerWidth(), 0, Disp, ShadowRegI32, 0, 1,
SMLoc(), SMLoc()));
Op->addMemOperands(Inst, 5);
EmitInstruction(Out, Inst);
}
EmitInstruction(
Out, MCInstBuilder(X86::TEST8rr).addReg(ShadowRegI8).addReg(ShadowRegI8));
MCSymbol *DoneSym = Ctx.createTempSymbol();
const MCExpr *DoneExpr = MCSymbolRefExpr::create(DoneSym, Ctx);
EmitInstruction(Out, MCInstBuilder(X86::JE_1).addExpr(DoneExpr));
EmitInstruction(Out, MCInstBuilder(X86::MOV32rr).addReg(ScratchRegI32).addReg(
AddressRegI32));
EmitInstruction(Out, MCInstBuilder(X86::AND32ri)
.addReg(ScratchRegI32)
.addReg(ScratchRegI32)
.addImm(7));
switch (AccessSize) {
default: llvm_unreachable("Incorrect access size");
case 1:
break;
case 2: {
const MCExpr *Disp = MCConstantExpr::create(1, Ctx);
std::unique_ptr<X86Operand> Op(
X86Operand::CreateMem(getPointerWidth(), 0, Disp, ScratchRegI32, 0, 1,
SMLoc(), SMLoc()));
EmitLEA(*Op, 32, ScratchRegI32, Out);
break;
}
case 4:
EmitInstruction(Out, MCInstBuilder(X86::ADD32ri8)
.addReg(ScratchRegI32)
.addReg(ScratchRegI32)
.addImm(3));
break;
}
EmitInstruction(
Out,
MCInstBuilder(X86::MOVSX32rr8).addReg(ShadowRegI32).addReg(ShadowRegI8));
EmitInstruction(Out, MCInstBuilder(X86::CMP32rr).addReg(ScratchRegI32).addReg(
ShadowRegI32));
EmitInstruction(Out, MCInstBuilder(X86::JL_1).addExpr(DoneExpr));
EmitCallAsanReport(AccessSize, IsWrite, Ctx, Out, RegCtx);
EmitLabel(Out, DoneSym);
}
void X86AddressSanitizer32::InstrumentMemOperandLarge(
X86Operand &Op, unsigned AccessSize, bool IsWrite,
const RegisterContext &RegCtx, MCContext &Ctx, MCStreamer &Out) {
unsigned AddressRegI32 = RegCtx.AddressReg(32);
unsigned ShadowRegI32 = RegCtx.ShadowReg(32);
ComputeMemOperandAddress(Op, 32, AddressRegI32, Ctx, Out);
EmitInstruction(Out, MCInstBuilder(X86::MOV32rr).addReg(ShadowRegI32).addReg(
AddressRegI32));
EmitInstruction(Out, MCInstBuilder(X86::SHR32ri)
.addReg(ShadowRegI32)
.addReg(ShadowRegI32)
.addImm(3));
{
MCInst Inst;
switch (AccessSize) {
default: llvm_unreachable("Incorrect access size");
case 8:
Inst.setOpcode(X86::CMP8mi);
break;
case 16:
Inst.setOpcode(X86::CMP16mi);
break;
}
const MCExpr *Disp = MCConstantExpr::create(kShadowOffset, Ctx);
std::unique_ptr<X86Operand> Op(
X86Operand::CreateMem(getPointerWidth(), 0, Disp, ShadowRegI32, 0, 1,
SMLoc(), SMLoc()));
Op->addMemOperands(Inst, 5);
Inst.addOperand(MCOperand::createImm(0));
EmitInstruction(Out, Inst);
}
MCSymbol *DoneSym = Ctx.createTempSymbol();
const MCExpr *DoneExpr = MCSymbolRefExpr::create(DoneSym, Ctx);
EmitInstruction(Out, MCInstBuilder(X86::JE_1).addExpr(DoneExpr));
EmitCallAsanReport(AccessSize, IsWrite, Ctx, Out, RegCtx);
EmitLabel(Out, DoneSym);
}
void X86AddressSanitizer32::InstrumentMOVSImpl(unsigned AccessSize,
MCContext &Ctx,
MCStreamer &Out) {
StoreFlags(Out);
// No need to test when ECX is equals to zero.
MCSymbol *DoneSym = Ctx.createTempSymbol();
const MCExpr *DoneExpr = MCSymbolRefExpr::create(DoneSym, Ctx);
EmitInstruction(
Out, MCInstBuilder(X86::TEST32rr).addReg(X86::ECX).addReg(X86::ECX));
EmitInstruction(Out, MCInstBuilder(X86::JE_1).addExpr(DoneExpr));
// Instrument first and last elements in src and dst range.
InstrumentMOVSBase(X86::EDI /* DstReg */, X86::ESI /* SrcReg */,
X86::ECX /* CntReg */, AccessSize, Ctx, Out);
EmitLabel(Out, DoneSym);
RestoreFlags(Out);
}
class X86AddressSanitizer64 : public X86AddressSanitizer {
public:
static const long kShadowOffset = 0x7fff8000;
X86AddressSanitizer64(const MCSubtargetInfo *&STI)
: X86AddressSanitizer(STI) {}
~X86AddressSanitizer64() override = default;
unsigned GetFrameReg(const MCContext &Ctx, MCStreamer &Out) {
unsigned FrameReg = GetFrameRegGeneric(Ctx, Out);
if (FrameReg == X86::NoRegister)
return FrameReg;
return getX86SubSuperRegister(FrameReg, 64);
}
void SpillReg(MCStreamer &Out, unsigned Reg) {
EmitInstruction(Out, MCInstBuilder(X86::PUSH64r).addReg(Reg));
OrigSPOffset -= 8;
}
void RestoreReg(MCStreamer &Out, unsigned Reg) {
EmitInstruction(Out, MCInstBuilder(X86::POP64r).addReg(Reg));
OrigSPOffset += 8;
}
void StoreFlags(MCStreamer &Out) {
EmitInstruction(Out, MCInstBuilder(X86::PUSHF64));
OrigSPOffset -= 8;
}
void RestoreFlags(MCStreamer &Out) {
EmitInstruction(Out, MCInstBuilder(X86::POPF64));
OrigSPOffset += 8;
}
void InstrumentMemOperandPrologue(const RegisterContext &RegCtx,
MCContext &Ctx,
MCStreamer &Out) override {
unsigned LocalFrameReg = RegCtx.ChooseFrameReg(64);
assert(LocalFrameReg != X86::NoRegister);
const MCRegisterInfo *MRI = Ctx.getRegisterInfo();
unsigned FrameReg = GetFrameReg(Ctx, Out);
if (MRI && FrameReg != X86::NoRegister) {
SpillReg(Out, X86::RBP);
if (FrameReg == X86::RSP) {
Out.EmitCFIAdjustCfaOffset(8 /* byte size of the LocalFrameReg */);
Out.EmitCFIRelOffset(
MRI->getDwarfRegNum(LocalFrameReg, true /* IsEH */), 0);
}
EmitInstruction(
Out,
MCInstBuilder(X86::MOV64rr).addReg(LocalFrameReg).addReg(FrameReg));
Out.EmitCFIRememberState();
Out.EmitCFIDefCfaRegister(
MRI->getDwarfRegNum(LocalFrameReg, true /* IsEH */));
}
EmitAdjustRSP(Ctx, Out, -128);
SpillReg(Out, RegCtx.ShadowReg(64));
SpillReg(Out, RegCtx.AddressReg(64));
if (RegCtx.ScratchReg(64) != X86::NoRegister)
SpillReg(Out, RegCtx.ScratchReg(64));
StoreFlags(Out);
}
void InstrumentMemOperandEpilogue(const RegisterContext &RegCtx,
MCContext &Ctx,
MCStreamer &Out) override {
unsigned LocalFrameReg = RegCtx.ChooseFrameReg(64);
assert(LocalFrameReg != X86::NoRegister);
RestoreFlags(Out);
if (RegCtx.ScratchReg(64) != X86::NoRegister)
RestoreReg(Out, RegCtx.ScratchReg(64));
RestoreReg(Out, RegCtx.AddressReg(64));
RestoreReg(Out, RegCtx.ShadowReg(64));
EmitAdjustRSP(Ctx, Out, 128);
unsigned FrameReg = GetFrameReg(Ctx, Out);
if (Ctx.getRegisterInfo() && FrameReg != X86::NoRegister) {
RestoreReg(Out, LocalFrameReg);
Out.EmitCFIRestoreState();
if (FrameReg == X86::RSP)
Out.EmitCFIAdjustCfaOffset(-8 /* byte size of the LocalFrameReg */);
}
}
void InstrumentMemOperandSmall(X86Operand &Op, unsigned AccessSize,
bool IsWrite,
const RegisterContext &RegCtx,
MCContext &Ctx,
MCStreamer &Out) override;
void InstrumentMemOperandLarge(X86Operand &Op, unsigned AccessSize,
bool IsWrite,
const RegisterContext &RegCtx,
MCContext &Ctx,
MCStreamer &Out) override;
void InstrumentMOVSImpl(unsigned AccessSize, MCContext &Ctx,
MCStreamer &Out) override;
private:
void EmitAdjustRSP(MCContext &Ctx, MCStreamer &Out, long Offset) {
const MCExpr *Disp = MCConstantExpr::create(Offset, Ctx);
std::unique_ptr<X86Operand> Op(
X86Operand::CreateMem(getPointerWidth(), 0, Disp, X86::RSP, 0, 1,
SMLoc(), SMLoc()));
EmitLEA(*Op, 64, X86::RSP, Out);
OrigSPOffset += Offset;
}
void EmitCallAsanReport(unsigned AccessSize, bool IsWrite, MCContext &Ctx,
MCStreamer &Out, const RegisterContext &RegCtx) {
EmitInstruction(Out, MCInstBuilder(X86::CLD));
EmitInstruction(Out, MCInstBuilder(X86::MMX_EMMS));
EmitInstruction(Out, MCInstBuilder(X86::AND64ri8)
.addReg(X86::RSP)
.addReg(X86::RSP)
.addImm(-16));
if (RegCtx.AddressReg(64) != X86::RDI) {
EmitInstruction(Out, MCInstBuilder(X86::MOV64rr).addReg(X86::RDI).addReg(
RegCtx.AddressReg(64)));
}
MCSymbol *FnSym = Ctx.getOrCreateSymbol(Twine("__asan_report_") +
(IsWrite ? "store" : "load") +
Twine(AccessSize));
const MCSymbolRefExpr *FnExpr =
MCSymbolRefExpr::create(FnSym, MCSymbolRefExpr::VK_PLT, Ctx);
EmitInstruction(Out, MCInstBuilder(X86::CALL64pcrel32).addExpr(FnExpr));
}
};
} // end anonymous namespace
void X86AddressSanitizer64::InstrumentMemOperandSmall(
X86Operand &Op, unsigned AccessSize, bool IsWrite,
const RegisterContext &RegCtx, MCContext &Ctx, MCStreamer &Out) {
unsigned AddressRegI64 = RegCtx.AddressReg(64);
unsigned AddressRegI32 = RegCtx.AddressReg(32);
unsigned ShadowRegI64 = RegCtx.ShadowReg(64);
unsigned ShadowRegI32 = RegCtx.ShadowReg(32);
unsigned ShadowRegI8 = RegCtx.ShadowReg(8);
assert(RegCtx.ScratchReg(32) != X86::NoRegister);
unsigned ScratchRegI32 = RegCtx.ScratchReg(32);
ComputeMemOperandAddress(Op, 64, AddressRegI64, Ctx, Out);
EmitInstruction(Out, MCInstBuilder(X86::MOV64rr).addReg(ShadowRegI64).addReg(
AddressRegI64));
EmitInstruction(Out, MCInstBuilder(X86::SHR64ri)
.addReg(ShadowRegI64)
.addReg(ShadowRegI64)
.addImm(3));
{
MCInst Inst;
Inst.setOpcode(X86::MOV8rm);
Inst.addOperand(MCOperand::createReg(ShadowRegI8));
const MCExpr *Disp = MCConstantExpr::create(kShadowOffset, Ctx);
std::unique_ptr<X86Operand> Op(
X86Operand::CreateMem(getPointerWidth(), 0, Disp, ShadowRegI64, 0, 1,
SMLoc(), SMLoc()));
Op->addMemOperands(Inst, 5);
EmitInstruction(Out, Inst);
}
EmitInstruction(
Out, MCInstBuilder(X86::TEST8rr).addReg(ShadowRegI8).addReg(ShadowRegI8));
MCSymbol *DoneSym = Ctx.createTempSymbol();
const MCExpr *DoneExpr = MCSymbolRefExpr::create(DoneSym, Ctx);
EmitInstruction(Out, MCInstBuilder(X86::JE_1).addExpr(DoneExpr));
EmitInstruction(Out, MCInstBuilder(X86::MOV32rr).addReg(ScratchRegI32).addReg(
AddressRegI32));
EmitInstruction(Out, MCInstBuilder(X86::AND32ri)
.addReg(ScratchRegI32)
.addReg(ScratchRegI32)
.addImm(7));
switch (AccessSize) {
default: llvm_unreachable("Incorrect access size");
case 1:
break;
case 2: {
const MCExpr *Disp = MCConstantExpr::create(1, Ctx);
std::unique_ptr<X86Operand> Op(
X86Operand::CreateMem(getPointerWidth(), 0, Disp, ScratchRegI32, 0, 1,
SMLoc(), SMLoc()));
EmitLEA(*Op, 32, ScratchRegI32, Out);
break;
}
case 4:
EmitInstruction(Out, MCInstBuilder(X86::ADD32ri8)
.addReg(ScratchRegI32)
.addReg(ScratchRegI32)
.addImm(3));
break;
}
EmitInstruction(
Out,
MCInstBuilder(X86::MOVSX32rr8).addReg(ShadowRegI32).addReg(ShadowRegI8));
EmitInstruction(Out, MCInstBuilder(X86::CMP32rr).addReg(ScratchRegI32).addReg(
ShadowRegI32));
EmitInstruction(Out, MCInstBuilder(X86::JL_1).addExpr(DoneExpr));
EmitCallAsanReport(AccessSize, IsWrite, Ctx, Out, RegCtx);
EmitLabel(Out, DoneSym);
}
void X86AddressSanitizer64::InstrumentMemOperandLarge(
X86Operand &Op, unsigned AccessSize, bool IsWrite,
const RegisterContext &RegCtx, MCContext &Ctx, MCStreamer &Out) {
unsigned AddressRegI64 = RegCtx.AddressReg(64);
unsigned ShadowRegI64 = RegCtx.ShadowReg(64);
ComputeMemOperandAddress(Op, 64, AddressRegI64, Ctx, Out);
EmitInstruction(Out, MCInstBuilder(X86::MOV64rr).addReg(ShadowRegI64).addReg(
AddressRegI64));
EmitInstruction(Out, MCInstBuilder(X86::SHR64ri)
.addReg(ShadowRegI64)
.addReg(ShadowRegI64)
.addImm(3));
{
MCInst Inst;
switch (AccessSize) {
default: llvm_unreachable("Incorrect access size");
case 8:
Inst.setOpcode(X86::CMP8mi);
break;
case 16:
Inst.setOpcode(X86::CMP16mi);
break;
}
const MCExpr *Disp = MCConstantExpr::create(kShadowOffset, Ctx);
std::unique_ptr<X86Operand> Op(
X86Operand::CreateMem(getPointerWidth(), 0, Disp, ShadowRegI64, 0, 1,
SMLoc(), SMLoc()));
Op->addMemOperands(Inst, 5);
Inst.addOperand(MCOperand::createImm(0));
EmitInstruction(Out, Inst);
}
MCSymbol *DoneSym = Ctx.createTempSymbol();
const MCExpr *DoneExpr = MCSymbolRefExpr::create(DoneSym, Ctx);
EmitInstruction(Out, MCInstBuilder(X86::JE_1).addExpr(DoneExpr));
EmitCallAsanReport(AccessSize, IsWrite, Ctx, Out, RegCtx);
EmitLabel(Out, DoneSym);
}
void X86AddressSanitizer64::InstrumentMOVSImpl(unsigned AccessSize,
MCContext &Ctx,
MCStreamer &Out) {
StoreFlags(Out);
// No need to test when RCX is equals to zero.
MCSymbol *DoneSym = Ctx.createTempSymbol();
const MCExpr *DoneExpr = MCSymbolRefExpr::create(DoneSym, Ctx);
EmitInstruction(
Out, MCInstBuilder(X86::TEST64rr).addReg(X86::RCX).addReg(X86::RCX));
EmitInstruction(Out, MCInstBuilder(X86::JE_1).addExpr(DoneExpr));
// Instrument first and last elements in src and dst range.
InstrumentMOVSBase(X86::RDI /* DstReg */, X86::RSI /* SrcReg */,
X86::RCX /* CntReg */, AccessSize, Ctx, Out);
EmitLabel(Out, DoneSym);
RestoreFlags(Out);
}
X86AsmInstrumentation::X86AsmInstrumentation(const MCSubtargetInfo *&STI)
: STI(STI) {}
X86AsmInstrumentation::~X86AsmInstrumentation() = default;
void X86AsmInstrumentation::InstrumentAndEmitInstruction(
const MCInst &Inst, OperandVector &Operands, MCContext &Ctx,
const MCInstrInfo &MII, MCStreamer &Out, bool PrintSchedInfoEnabled) {
EmitInstruction(Out, Inst, PrintSchedInfoEnabled);
}
void X86AsmInstrumentation::EmitInstruction(MCStreamer &Out, const MCInst &Inst,
bool PrintSchedInfoEnabled) {
Out.EmitInstruction(Inst, *STI, PrintSchedInfoEnabled);
}
unsigned X86AsmInstrumentation::GetFrameRegGeneric(const MCContext &Ctx,
MCStreamer &Out) {
if (!Out.getNumFrameInfos()) // No active dwarf frame
return X86::NoRegister;
const MCDwarfFrameInfo &Frame = Out.getDwarfFrameInfos().back();
if (Frame.End) // Active dwarf frame is closed
return X86::NoRegister;
const MCRegisterInfo *MRI = Ctx.getRegisterInfo();
if (!MRI) // No register info
return X86::NoRegister;
if (InitialFrameReg) {
// FrameReg is set explicitly, we're instrumenting a MachineFunction.
return InitialFrameReg;
}
return MRI->getLLVMRegNum(Frame.CurrentCfaRegister, true /* IsEH */);
}
X86AsmInstrumentation *
llvm::CreateX86AsmInstrumentation(const MCTargetOptions &MCOptions,
const MCContext &Ctx,
const MCSubtargetInfo *&STI) {
Triple T(STI->getTargetTriple());
const bool hasCompilerRTSupport = T.isOSLinux();
if (ClAsanInstrumentAssembly && hasCompilerRTSupport &&
MCOptions.SanitizeAddress) {
if (STI->getFeatureBits()[X86::Mode32Bit] != 0)
return new X86AddressSanitizer32(STI);
if (STI->getFeatureBits()[X86::Mode64Bit] != 0)
return new X86AddressSanitizer64(STI);
}
return new X86AsmInstrumentation(STI);
}
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