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llvm-mirror/lib/Transforms/Instrumentation/MemorySanitizer.cpp
Evgeniy Stepanov fee15f88f9 [msan] Use explicitely aligned stores and loads with function argument shadow. 
Use explicitely aligned store and load instructions to deal with argument and
retval shadow. This matters when an argument's alignment is higher than
__msan_param_tls alignment (which is the case with __m128i).

llvm-svn: 169859
2012-12-11 12:34:09 +00:00

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//===-- MemorySanitizer.cpp - detector of uninitialized reads -------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
/// \file
/// This file is a part of MemorySanitizer, a detector of uninitialized
/// reads.
///
/// Status: early prototype.
///
/// The algorithm of the tool is similar to Memcheck
/// (http://goo.gl/QKbem). We associate a few shadow bits with every
/// byte of the application memory, poison the shadow of the malloc-ed
/// or alloca-ed memory, load the shadow bits on every memory read,
/// propagate the shadow bits through some of the arithmetic
/// instruction (including MOV), store the shadow bits on every memory
/// write, report a bug on some other instructions (e.g. JMP) if the
/// associated shadow is poisoned.
///
/// But there are differences too. The first and the major one:
/// compiler instrumentation instead of binary instrumentation. This
/// gives us much better register allocation, possible compiler
/// optimizations and a fast start-up. But this brings the major issue
/// as well: msan needs to see all program events, including system
/// calls and reads/writes in system libraries, so we either need to
/// compile *everything* with msan or use a binary translation
/// component (e.g. DynamoRIO) to instrument pre-built libraries.
/// Another difference from Memcheck is that we use 8 shadow bits per
/// byte of application memory and use a direct shadow mapping. This
/// greatly simplifies the instrumentation code and avoids races on
/// shadow updates (Memcheck is single-threaded so races are not a
/// concern there. Memcheck uses 2 shadow bits per byte with a slow
/// path storage that uses 8 bits per byte).
///
/// The default value of shadow is 0, which means "clean" (not poisoned).
///
/// Every module initializer should call __msan_init to ensure that the
/// shadow memory is ready. On error, __msan_warning is called. Since
/// parameters and return values may be passed via registers, we have a
/// specialized thread-local shadow for return values
/// (__msan_retval_tls) and parameters (__msan_param_tls).
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "msan"
#include "llvm/Transforms/Instrumentation.h"
#include "BlackList.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/ValueMap.h"
#include "llvm/DataLayout.h"
#include "llvm/Function.h"
#include "llvm/IRBuilder.h"
#include "llvm/InlineAsm.h"
#include "llvm/InstVisitor.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/LLVMContext.h"
#include "llvm/MDBuilder.h"
#include "llvm/Module.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"
#include "llvm/Type.h"
using namespace llvm;
static const uint64_t kShadowMask32 = 1ULL << 31;
static const uint64_t kShadowMask64 = 1ULL << 46;
static const uint64_t kOriginOffset32 = 1ULL << 30;
static const uint64_t kOriginOffset64 = 1ULL << 45;
static const uint64_t kShadowTLSAlignment = 8;
// This is an important flag that makes the reports much more
// informative at the cost of greater slowdown. Not fully implemented
// yet.
// FIXME: this should be a top-level clang flag, e.g.
// -fmemory-sanitizer-full.
static cl::opt<bool> ClTrackOrigins("msan-track-origins",
cl::desc("Track origins (allocation sites) of poisoned memory"),
cl::Hidden, cl::init(false));
static cl::opt<bool> ClKeepGoing("msan-keep-going",
cl::desc("keep going after reporting a UMR"),
cl::Hidden, cl::init(false));
static cl::opt<bool> ClPoisonStack("msan-poison-stack",
cl::desc("poison uninitialized stack variables"),
cl::Hidden, cl::init(true));
static cl::opt<bool> ClPoisonStackWithCall("msan-poison-stack-with-call",
cl::desc("poison uninitialized stack variables with a call"),
cl::Hidden, cl::init(false));
static cl::opt<int> ClPoisonStackPattern("msan-poison-stack-pattern",
cl::desc("poison uninitialized stack variables with the given patter"),
cl::Hidden, cl::init(0xff));
static cl::opt<bool> ClHandleICmp("msan-handle-icmp",
cl::desc("propagate shadow through ICmpEQ and ICmpNE"),
cl::Hidden, cl::init(true));
static cl::opt<bool> ClStoreCleanOrigin("msan-store-clean-origin",
cl::desc("store origin for clean (fully initialized) values"),
cl::Hidden, cl::init(false));
// This flag controls whether we check the shadow of the address
// operand of load or store. Such bugs are very rare, since load from
// a garbage address typically results in SEGV, but still happen
// (e.g. only lower bits of address are garbage, or the access happens
// early at program startup where malloc-ed memory is more likely to
// be zeroed. As of 2012-08-28 this flag adds 20% slowdown.
static cl::opt<bool> ClCheckAccessAddress("msan-check-access-address",
cl::desc("report accesses through a pointer which has poisoned shadow"),
cl::Hidden, cl::init(true));
static cl::opt<bool> ClDumpStrictInstructions("msan-dump-strict-instructions",
cl::desc("print out instructions with default strict semantics"),
cl::Hidden, cl::init(false));
static cl::opt<std::string> ClBlackListFile("msan-blacklist",
cl::desc("File containing the list of functions where MemorySanitizer "
"should not report bugs"), cl::Hidden);
namespace {
/// \brief An instrumentation pass implementing detection of uninitialized
/// reads.
///
/// MemorySanitizer: instrument the code in module to find
/// uninitialized reads.
class MemorySanitizer : public FunctionPass {
public:
MemorySanitizer() : FunctionPass(ID), TD(0), WarningFn(0) { }
const char *getPassName() const { return "MemorySanitizer"; }
bool runOnFunction(Function &F);
bool doInitialization(Module &M);
static char ID; // Pass identification, replacement for typeid.
private:
void initializeCallbacks(Module &M);
DataLayout *TD;
LLVMContext *C;
Type *IntptrTy;
Type *OriginTy;
/// \brief Thread-local shadow storage for function parameters.
GlobalVariable *ParamTLS;
/// \brief Thread-local origin storage for function parameters.
GlobalVariable *ParamOriginTLS;
/// \brief Thread-local shadow storage for function return value.
GlobalVariable *RetvalTLS;
/// \brief Thread-local origin storage for function return value.
GlobalVariable *RetvalOriginTLS;
/// \brief Thread-local shadow storage for in-register va_arg function
/// parameters (x86_64-specific).
GlobalVariable *VAArgTLS;
/// \brief Thread-local shadow storage for va_arg overflow area
/// (x86_64-specific).
GlobalVariable *VAArgOverflowSizeTLS;
/// \brief Thread-local space used to pass origin value to the UMR reporting
/// function.
GlobalVariable *OriginTLS;
/// \brief The run-time callback to print a warning.
Value *WarningFn;
/// \brief Run-time helper that copies origin info for a memory range.
Value *MsanCopyOriginFn;
/// \brief Run-time helper that generates a new origin value for a stack
/// allocation.
Value *MsanSetAllocaOriginFn;
/// \brief Run-time helper that poisons stack on function entry.
Value *MsanPoisonStackFn;
/// \brief MSan runtime replacements for memmove, memcpy and memset.
Value *MemmoveFn, *MemcpyFn, *MemsetFn;
/// \brief Address mask used in application-to-shadow address calculation.
/// ShadowAddr is computed as ApplicationAddr & ~ShadowMask.
uint64_t ShadowMask;
/// \brief Offset of the origin shadow from the "normal" shadow.
/// OriginAddr is computed as (ShadowAddr + OriginOffset) & ~3ULL
uint64_t OriginOffset;
/// \brief Branch weights for error reporting.
MDNode *ColdCallWeights;
/// \brief Branch weights for origin store.
MDNode *OriginStoreWeights;
/// \brief The blacklist.
OwningPtr<BlackList> BL;
/// \brief An empty volatile inline asm that prevents callback merge.
InlineAsm *EmptyAsm;
friend struct MemorySanitizerVisitor;
friend struct VarArgAMD64Helper;
};
} // namespace
char MemorySanitizer::ID = 0;
INITIALIZE_PASS(MemorySanitizer, "msan",
"MemorySanitizer: detects uninitialized reads.",
false, false)
FunctionPass *llvm::createMemorySanitizerPass() {
return new MemorySanitizer();
}
/// \brief Create a non-const global initialized with the given string.
///
/// Creates a writable global for Str so that we can pass it to the
/// run-time lib. Runtime uses first 4 bytes of the string to store the
/// frame ID, so the string needs to be mutable.
static GlobalVariable *createPrivateNonConstGlobalForString(Module &M,
StringRef Str) {
Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
return new GlobalVariable(M, StrConst->getType(), /*isConstant=*/false,
GlobalValue::PrivateLinkage, StrConst, "");
}
/// \brief Insert extern declaration of runtime-provided functions and globals.
void MemorySanitizer::initializeCallbacks(Module &M) {
// Only do this once.
if (WarningFn)
return;
IRBuilder<> IRB(*C);
// Create the callback.
// FIXME: this function should have "Cold" calling conv,
// which is not yet implemented.
StringRef WarningFnName = ClKeepGoing ? "__msan_warning"
: "__msan_warning_noreturn";
WarningFn = M.getOrInsertFunction(WarningFnName, IRB.getVoidTy(), NULL);
MsanCopyOriginFn = M.getOrInsertFunction(
"__msan_copy_origin", IRB.getVoidTy(), IRB.getInt8PtrTy(),
IRB.getInt8PtrTy(), IntptrTy, NULL);
MsanSetAllocaOriginFn = M.getOrInsertFunction(
"__msan_set_alloca_origin", IRB.getVoidTy(), IRB.getInt8PtrTy(), IntptrTy,
IRB.getInt8PtrTy(), NULL);
MsanPoisonStackFn = M.getOrInsertFunction(
"__msan_poison_stack", IRB.getVoidTy(), IRB.getInt8PtrTy(), IntptrTy, NULL);
MemmoveFn = M.getOrInsertFunction(
"__msan_memmove", IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
IntptrTy, NULL);
MemcpyFn = M.getOrInsertFunction(
"__msan_memcpy", IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
IntptrTy, NULL);
MemsetFn = M.getOrInsertFunction(
"__msan_memset", IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IRB.getInt32Ty(),
IntptrTy, NULL);
// Create globals.
RetvalTLS = new GlobalVariable(
M, ArrayType::get(IRB.getInt64Ty(), 8), false,
GlobalVariable::ExternalLinkage, 0, "__msan_retval_tls", 0,
GlobalVariable::GeneralDynamicTLSModel);
RetvalOriginTLS = new GlobalVariable(
M, OriginTy, false, GlobalVariable::ExternalLinkage, 0,
"__msan_retval_origin_tls", 0, GlobalVariable::GeneralDynamicTLSModel);
ParamTLS = new GlobalVariable(
M, ArrayType::get(IRB.getInt64Ty(), 1000), false,
GlobalVariable::ExternalLinkage, 0, "__msan_param_tls", 0,
GlobalVariable::GeneralDynamicTLSModel);
ParamOriginTLS = new GlobalVariable(
M, ArrayType::get(OriginTy, 1000), false, GlobalVariable::ExternalLinkage,
0, "__msan_param_origin_tls", 0, GlobalVariable::GeneralDynamicTLSModel);
VAArgTLS = new GlobalVariable(
M, ArrayType::get(IRB.getInt64Ty(), 1000), false,
GlobalVariable::ExternalLinkage, 0, "__msan_va_arg_tls", 0,
GlobalVariable::GeneralDynamicTLSModel);
VAArgOverflowSizeTLS = new GlobalVariable(
M, IRB.getInt64Ty(), false, GlobalVariable::ExternalLinkage, 0,
"__msan_va_arg_overflow_size_tls", 0,
GlobalVariable::GeneralDynamicTLSModel);
OriginTLS = new GlobalVariable(
M, IRB.getInt32Ty(), false, GlobalVariable::ExternalLinkage, 0,
"__msan_origin_tls", 0, GlobalVariable::GeneralDynamicTLSModel);
// We insert an empty inline asm after __msan_report* to avoid callback merge.
EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
StringRef(""), StringRef(""),
/*hasSideEffects=*/true);
}
/// \brief Module-level initialization.
///
/// inserts a call to __msan_init to the module's constructor list.
bool MemorySanitizer::doInitialization(Module &M) {
TD = getAnalysisIfAvailable<DataLayout>();
if (!TD)
return false;
BL.reset(new BlackList(ClBlackListFile));
C = &(M.getContext());
unsigned PtrSize = TD->getPointerSizeInBits(/* AddressSpace */0);
switch (PtrSize) {
case 64:
ShadowMask = kShadowMask64;
OriginOffset = kOriginOffset64;
break;
case 32:
ShadowMask = kShadowMask32;
OriginOffset = kOriginOffset32;
break;
default:
report_fatal_error("unsupported pointer size");
break;
}
IRBuilder<> IRB(*C);
IntptrTy = IRB.getIntPtrTy(TD);
OriginTy = IRB.getInt32Ty();
ColdCallWeights = MDBuilder(*C).createBranchWeights(1, 1000);
OriginStoreWeights = MDBuilder(*C).createBranchWeights(1, 1000);
// Insert a call to __msan_init/__msan_track_origins into the module's CTORs.
appendToGlobalCtors(M, cast<Function>(M.getOrInsertFunction(
"__msan_init", IRB.getVoidTy(), NULL)), 0);
new GlobalVariable(M, IRB.getInt32Ty(), true, GlobalValue::WeakODRLinkage,
IRB.getInt32(ClTrackOrigins), "__msan_track_origins");
return true;
}
namespace {
/// \brief A helper class that handles instrumentation of VarArg
/// functions on a particular platform.
///
/// Implementations are expected to insert the instrumentation
/// necessary to propagate argument shadow through VarArg function
/// calls. Visit* methods are called during an InstVisitor pass over
/// the function, and should avoid creating new basic blocks. A new
/// instance of this class is created for each instrumented function.
struct VarArgHelper {
/// \brief Visit a CallSite.
virtual void visitCallSite(CallSite &CS, IRBuilder<> &IRB) = 0;
/// \brief Visit a va_start call.
virtual void visitVAStartInst(VAStartInst &I) = 0;
/// \brief Visit a va_copy call.
virtual void visitVACopyInst(VACopyInst &I) = 0;
/// \brief Finalize function instrumentation.
///
/// This method is called after visiting all interesting (see above)
/// instructions in a function.
virtual void finalizeInstrumentation() = 0;
virtual ~VarArgHelper() {}
};
struct MemorySanitizerVisitor;
VarArgHelper*
CreateVarArgHelper(Function &Func, MemorySanitizer &Msan,
MemorySanitizerVisitor &Visitor);
/// This class does all the work for a given function. Store and Load
/// instructions store and load corresponding shadow and origin
/// values. Most instructions propagate shadow from arguments to their
/// return values. Certain instructions (most importantly, BranchInst)
/// test their argument shadow and print reports (with a runtime call) if it's
/// non-zero.
struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
Function &F;
MemorySanitizer &MS;
SmallVector<PHINode *, 16> ShadowPHINodes, OriginPHINodes;
ValueMap<Value*, Value*> ShadowMap, OriginMap;
bool InsertChecks;
OwningPtr<VarArgHelper> VAHelper;
// An unfortunate workaround for asymmetric lowering of va_arg stuff.
// See a comment in visitCallSite for more details.
static const unsigned AMD64GpEndOffset = 48; // AMD64 ABI Draft 0.99.6 p3.5.7
static const unsigned AMD64FpEndOffset = 176;
struct ShadowOriginAndInsertPoint {
Instruction *Shadow;
Instruction *Origin;
Instruction *OrigIns;
ShadowOriginAndInsertPoint(Instruction *S, Instruction *O, Instruction *I)
: Shadow(S), Origin(O), OrigIns(I) { }
ShadowOriginAndInsertPoint() : Shadow(0), Origin(0), OrigIns(0) { }
};
SmallVector<ShadowOriginAndInsertPoint, 16> InstrumentationList;
SmallVector<Instruction*, 16> StoreList;
MemorySanitizerVisitor(Function &F, MemorySanitizer &MS)
: F(F), MS(MS), VAHelper(CreateVarArgHelper(F, MS, *this)) {
InsertChecks = !MS.BL->isIn(F);
DEBUG(if (!InsertChecks)
dbgs() << "MemorySanitizer is not inserting checks into '"
<< F.getName() << "'\n");
}
void materializeStores() {
for (size_t i = 0, n = StoreList.size(); i < n; i++) {
StoreInst& I = *dyn_cast<StoreInst>(StoreList[i]);
IRBuilder<> IRB(&I);
Value *Val = I.getValueOperand();
Value *Addr = I.getPointerOperand();
Value *Shadow = getShadow(Val);
Value *ShadowPtr = getShadowPtr(Addr, Shadow->getType(), IRB);
StoreInst *NewSI = IRB.CreateAlignedStore(Shadow, ShadowPtr, I.getAlignment());
DEBUG(dbgs() << " STORE: " << *NewSI << "\n");
(void)NewSI;
// If the store is volatile, add a check.
if (I.isVolatile())
insertCheck(Val, &I);
if (ClCheckAccessAddress)
insertCheck(Addr, &I);
if (ClTrackOrigins) {
if (ClStoreCleanOrigin || isa<StructType>(Shadow->getType())) {
IRB.CreateAlignedStore(getOrigin(Val), getOriginPtr(Addr, IRB), I.getAlignment());
} else {
Value *ConvertedShadow = convertToShadowTyNoVec(Shadow, IRB);
Constant *Cst = dyn_cast_or_null<Constant>(ConvertedShadow);
// TODO(eugenis): handle non-zero constant shadow by inserting an
// unconditional check (can not simply fail compilation as this could
// be in the dead code).
if (Cst)
continue;
Value *Cmp = IRB.CreateICmpNE(ConvertedShadow,
getCleanShadow(ConvertedShadow), "_mscmp");
Instruction *CheckTerm =
SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false, MS.OriginStoreWeights);
IRBuilder<> IRBNewBlock(CheckTerm);
IRBNewBlock.CreateAlignedStore(getOrigin(Val),
getOriginPtr(Addr, IRBNewBlock), I.getAlignment());
}
}
}
}
void materializeChecks() {
for (size_t i = 0, n = InstrumentationList.size(); i < n; i++) {
Instruction *Shadow = InstrumentationList[i].Shadow;
Instruction *OrigIns = InstrumentationList[i].OrigIns;
IRBuilder<> IRB(OrigIns);
DEBUG(dbgs() << " SHAD0 : " << *Shadow << "\n");
Value *ConvertedShadow = convertToShadowTyNoVec(Shadow, IRB);
DEBUG(dbgs() << " SHAD1 : " << *ConvertedShadow << "\n");
Value *Cmp = IRB.CreateICmpNE(ConvertedShadow,
getCleanShadow(ConvertedShadow), "_mscmp");
Instruction *CheckTerm =
SplitBlockAndInsertIfThen(cast<Instruction>(Cmp),
/* Unreachable */ !ClKeepGoing,
MS.ColdCallWeights);
IRB.SetInsertPoint(CheckTerm);
if (ClTrackOrigins) {
Instruction *Origin = InstrumentationList[i].Origin;
IRB.CreateStore(Origin ? (Value*)Origin : (Value*)IRB.getInt32(0),
MS.OriginTLS);
}
CallInst *Call = IRB.CreateCall(MS.WarningFn);
Call->setDebugLoc(OrigIns->getDebugLoc());
IRB.CreateCall(MS.EmptyAsm);
DEBUG(dbgs() << " CHECK: " << *Cmp << "\n");
}
DEBUG(dbgs() << "DONE:\n" << F);
}
/// \brief Add MemorySanitizer instrumentation to a function.
bool runOnFunction() {
MS.initializeCallbacks(*F.getParent());
if (!MS.TD) return false;
// Iterate all BBs in depth-first order and create shadow instructions
// for all instructions (where applicable).
// For PHI nodes we create dummy shadow PHIs which will be finalized later.
for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
BasicBlock *BB = *DI;
visit(*BB);
}
// Finalize PHI nodes.
for (size_t i = 0, n = ShadowPHINodes.size(); i < n; i++) {
PHINode *PN = ShadowPHINodes[i];
PHINode *PNS = cast<PHINode>(getShadow(PN));
PHINode *PNO = ClTrackOrigins ? cast<PHINode>(getOrigin(PN)) : 0;
size_t NumValues = PN->getNumIncomingValues();
for (size_t v = 0; v < NumValues; v++) {
PNS->addIncoming(getShadow(PN, v), PN->getIncomingBlock(v));
if (PNO)
PNO->addIncoming(getOrigin(PN, v), PN->getIncomingBlock(v));
}
}
VAHelper->finalizeInstrumentation();
// Delayed instrumentation of StoreInst.
// This may add new checks to be inserted later.
materializeStores();
// Insert shadow value checks.
materializeChecks();
return true;
}
/// \brief Compute the shadow type that corresponds to a given Value.
Type *getShadowTy(Value *V) {
return getShadowTy(V->getType());
}
/// \brief Compute the shadow type that corresponds to a given Type.
Type *getShadowTy(Type *OrigTy) {
if (!OrigTy->isSized()) {
return 0;
}
// For integer type, shadow is the same as the original type.
// This may return weird-sized types like i1.
if (IntegerType *IT = dyn_cast<IntegerType>(OrigTy))
return IT;
if (VectorType *VT = dyn_cast<VectorType>(OrigTy))
return VectorType::getInteger(VT);
if (StructType *ST = dyn_cast<StructType>(OrigTy)) {
SmallVector<Type*, 4> Elements;
for (unsigned i = 0, n = ST->getNumElements(); i < n; i++)
Elements.push_back(getShadowTy(ST->getElementType(i)));
StructType *Res = StructType::get(*MS.C, Elements, ST->isPacked());
DEBUG(dbgs() << "getShadowTy: " << *ST << " ===> " << *Res << "\n");
return Res;
}
uint32_t TypeSize = MS.TD->getTypeStoreSizeInBits(OrigTy);
return IntegerType::get(*MS.C, TypeSize);
}
/// \brief Flatten a vector type.
Type *getShadowTyNoVec(Type *ty) {
if (VectorType *vt = dyn_cast<VectorType>(ty))
return IntegerType::get(*MS.C, vt->getBitWidth());
return ty;
}
/// \brief Convert a shadow value to it's flattened variant.
Value *convertToShadowTyNoVec(Value *V, IRBuilder<> &IRB) {
Type *Ty = V->getType();
Type *NoVecTy = getShadowTyNoVec(Ty);
if (Ty == NoVecTy) return V;
return IRB.CreateBitCast(V, NoVecTy);
}
/// \brief Compute the shadow address that corresponds to a given application
/// address.
///
/// Shadow = Addr & ~ShadowMask.
Value *getShadowPtr(Value *Addr, Type *ShadowTy,
IRBuilder<> &IRB) {
Value *ShadowLong =
IRB.CreateAnd(IRB.CreatePointerCast(Addr, MS.IntptrTy),
ConstantInt::get(MS.IntptrTy, ~MS.ShadowMask));
return IRB.CreateIntToPtr(ShadowLong, PointerType::get(ShadowTy, 0));
}
/// \brief Compute the origin address that corresponds to a given application
/// address.
///
/// OriginAddr = (ShadowAddr + OriginOffset) & ~3ULL
Value *getOriginPtr(Value *Addr, IRBuilder<> &IRB) {
Value *ShadowLong =
IRB.CreateAnd(IRB.CreatePointerCast(Addr, MS.IntptrTy),
ConstantInt::get(MS.IntptrTy, ~MS.ShadowMask));
Value *Add =
IRB.CreateAdd(ShadowLong,
ConstantInt::get(MS.IntptrTy, MS.OriginOffset));
Value *SecondAnd =
IRB.CreateAnd(Add, ConstantInt::get(MS.IntptrTy, ~3ULL));
return IRB.CreateIntToPtr(SecondAnd, PointerType::get(IRB.getInt32Ty(), 0));
}
/// \brief Compute the shadow address for a given function argument.
///
/// Shadow = ParamTLS+ArgOffset.
Value *getShadowPtrForArgument(Value *A, IRBuilder<> &IRB,
int ArgOffset) {
Value *Base = IRB.CreatePointerCast(MS.ParamTLS, MS.IntptrTy);
Base = IRB.CreateAdd(Base, ConstantInt::get(MS.IntptrTy, ArgOffset));
return IRB.CreateIntToPtr(Base, PointerType::get(getShadowTy(A), 0),
"_msarg");
}
/// \brief Compute the origin address for a given function argument.
Value *getOriginPtrForArgument(Value *A, IRBuilder<> &IRB,
int ArgOffset) {
if (!ClTrackOrigins) return 0;
Value *Base = IRB.CreatePointerCast(MS.ParamOriginTLS, MS.IntptrTy);
Base = IRB.CreateAdd(Base, ConstantInt::get(MS.IntptrTy, ArgOffset));
return IRB.CreateIntToPtr(Base, PointerType::get(MS.OriginTy, 0),
"_msarg_o");
}
/// \brief Compute the shadow address for a retval.
Value *getShadowPtrForRetval(Value *A, IRBuilder<> &IRB) {
Value *Base = IRB.CreatePointerCast(MS.RetvalTLS, MS.IntptrTy);
return IRB.CreateIntToPtr(Base, PointerType::get(getShadowTy(A), 0),
"_msret");
}
/// \brief Compute the origin address for a retval.
Value *getOriginPtrForRetval(IRBuilder<> &IRB) {
// We keep a single origin for the entire retval. Might be too optimistic.
return MS.RetvalOriginTLS;
}
/// \brief Set SV to be the shadow value for V.
void setShadow(Value *V, Value *SV) {
assert(!ShadowMap.count(V) && "Values may only have one shadow");
ShadowMap[V] = SV;
}
/// \brief Set Origin to be the origin value for V.
void setOrigin(Value *V, Value *Origin) {
if (!ClTrackOrigins) return;
assert(!OriginMap.count(V) && "Values may only have one origin");
DEBUG(dbgs() << "ORIGIN: " << *V << " ==> " << *Origin << "\n");
OriginMap[V] = Origin;
}
/// \brief Create a clean shadow value for a given value.
///
/// Clean shadow (all zeroes) means all bits of the value are defined
/// (initialized).
Value *getCleanShadow(Value *V) {
Type *ShadowTy = getShadowTy(V);
if (!ShadowTy)
return 0;
return Constant::getNullValue(ShadowTy);
}
/// \brief Create a dirty shadow of a given shadow type.
Constant *getPoisonedShadow(Type *ShadowTy) {
assert(ShadowTy);
if (isa<IntegerType>(ShadowTy) || isa<VectorType>(ShadowTy))
return Constant::getAllOnesValue(ShadowTy);
StructType *ST = cast<StructType>(ShadowTy);
SmallVector<Constant *, 4> Vals;
for (unsigned i = 0, n = ST->getNumElements(); i < n; i++)
Vals.push_back(getPoisonedShadow(ST->getElementType(i)));
return ConstantStruct::get(ST, Vals);
}
/// \brief Create a clean (zero) origin.
Value *getCleanOrigin() {
return Constant::getNullValue(MS.OriginTy);
}
/// \brief Get the shadow value for a given Value.
///
/// This function either returns the value set earlier with setShadow,
/// or extracts if from ParamTLS (for function arguments).
Value *getShadow(Value *V) {
if (Instruction *I = dyn_cast<Instruction>(V)) {
// For instructions the shadow is already stored in the map.
Value *Shadow = ShadowMap[V];
if (!Shadow) {
DEBUG(dbgs() << "No shadow: " << *V << "\n" << *(I->getParent()));
(void)I;
assert(Shadow && "No shadow for a value");
}
return Shadow;
}
if (UndefValue *U = dyn_cast<UndefValue>(V)) {
Value *AllOnes = getPoisonedShadow(getShadowTy(V));
DEBUG(dbgs() << "Undef: " << *U << " ==> " << *AllOnes << "\n");
(void)U;
return AllOnes;
}
if (Argument *A = dyn_cast<Argument>(V)) {
// For arguments we compute the shadow on demand and store it in the map.
Value **ShadowPtr = &ShadowMap[V];
if (*ShadowPtr)
return *ShadowPtr;
Function *F = A->getParent();
IRBuilder<> EntryIRB(F->getEntryBlock().getFirstNonPHI());
unsigned ArgOffset = 0;
for (Function::arg_iterator AI = F->arg_begin(), AE = F->arg_end();
AI != AE; ++AI) {
if (!AI->getType()->isSized()) {
DEBUG(dbgs() << "Arg is not sized\n");
continue;
}
unsigned Size = AI->hasByValAttr()
? MS.TD->getTypeAllocSize(AI->getType()->getPointerElementType())
: MS.TD->getTypeAllocSize(AI->getType());
if (A == AI) {
Value *Base = getShadowPtrForArgument(AI, EntryIRB, ArgOffset);
if (AI->hasByValAttr()) {
// ByVal pointer itself has clean shadow. We copy the actual
// argument shadow to the underlying memory.
Value *Cpy = EntryIRB.CreateMemCpy(
getShadowPtr(V, EntryIRB.getInt8Ty(), EntryIRB),
Base, Size, AI->getParamAlignment());
DEBUG(dbgs() << " ByValCpy: " << *Cpy << "\n");
(void)Cpy;
*ShadowPtr = getCleanShadow(V);
} else {
*ShadowPtr = EntryIRB.CreateLoad(Base);
}
DEBUG(dbgs() << " ARG: " << *AI << " ==> " <<
**ShadowPtr << "\n");
if (ClTrackOrigins) {
Value* OriginPtr = getOriginPtrForArgument(AI, EntryIRB, ArgOffset);
setOrigin(A, EntryIRB.CreateLoad(OriginPtr));
}
}
ArgOffset += DataLayout::RoundUpAlignment(Size, 8);
}
assert(*ShadowPtr && "Could not find shadow for an argument");
return *ShadowPtr;
}
// For everything else the shadow is zero.
return getCleanShadow(V);
}
/// \brief Get the shadow for i-th argument of the instruction I.
Value *getShadow(Instruction *I, int i) {
return getShadow(I->getOperand(i));
}
/// \brief Get the origin for a value.
Value *getOrigin(Value *V) {
if (!ClTrackOrigins) return 0;
if (isa<Instruction>(V) || isa<Argument>(V)) {
Value *Origin = OriginMap[V];
if (!Origin) {
DEBUG(dbgs() << "NO ORIGIN: " << *V << "\n");
Origin = getCleanOrigin();
}
return Origin;
}
return getCleanOrigin();
}
/// \brief Get the origin for i-th argument of the instruction I.
Value *getOrigin(Instruction *I, int i) {
return getOrigin(I->getOperand(i));
}
/// \brief Remember the place where a shadow check should be inserted.
///
/// This location will be later instrumented with a check that will print a
/// UMR warning in runtime if the value is not fully defined.
void insertCheck(Value *Val, Instruction *OrigIns) {
assert(Val);
if (!InsertChecks) return;
Instruction *Shadow = dyn_cast_or_null<Instruction>(getShadow(Val));
if (!Shadow) return;
#ifndef NDEBUG
Type *ShadowTy = Shadow->getType();
assert((isa<IntegerType>(ShadowTy) || isa<VectorType>(ShadowTy)) &&
"Can only insert checks for integer and vector shadow types");
#endif
Instruction *Origin = dyn_cast_or_null<Instruction>(getOrigin(Val));
InstrumentationList.push_back(
ShadowOriginAndInsertPoint(Shadow, Origin, OrigIns));
}
//------------------- Visitors.
/// \brief Instrument LoadInst
///
/// Loads the corresponding shadow and (optionally) origin.
/// Optionally, checks that the load address is fully defined.
void visitLoadInst(LoadInst &I) {
assert(I.getType()->isSized() && "Load type must have size");
IRBuilder<> IRB(&I);
Type *ShadowTy = getShadowTy(&I);
Value *Addr = I.getPointerOperand();
Value *ShadowPtr = getShadowPtr(Addr, ShadowTy, IRB);
setShadow(&I, IRB.CreateAlignedLoad(ShadowPtr, I.getAlignment(), "_msld"));
if (ClCheckAccessAddress)
insertCheck(I.getPointerOperand(), &I);
if (ClTrackOrigins)
setOrigin(&I, IRB.CreateAlignedLoad(getOriginPtr(Addr, IRB), I.getAlignment()));
}
/// \brief Instrument StoreInst
///
/// Stores the corresponding shadow and (optionally) origin.
/// Optionally, checks that the store address is fully defined.
/// Volatile stores check that the value being stored is fully defined.
void visitStoreInst(StoreInst &I) {
StoreList.push_back(&I);
}
// Vector manipulation.
void visitExtractElementInst(ExtractElementInst &I) {
insertCheck(I.getOperand(1), &I);
IRBuilder<> IRB(&I);
setShadow(&I, IRB.CreateExtractElement(getShadow(&I, 0), I.getOperand(1),
"_msprop"));
setOrigin(&I, getOrigin(&I, 0));
}
void visitInsertElementInst(InsertElementInst &I) {
insertCheck(I.getOperand(2), &I);
IRBuilder<> IRB(&I);
setShadow(&I, IRB.CreateInsertElement(getShadow(&I, 0), getShadow(&I, 1),
I.getOperand(2), "_msprop"));
setOriginForNaryOp(I);
}
void visitShuffleVectorInst(ShuffleVectorInst &I) {
insertCheck(I.getOperand(2), &I);
IRBuilder<> IRB(&I);
setShadow(&I, IRB.CreateShuffleVector(getShadow(&I, 0), getShadow(&I, 1),
I.getOperand(2), "_msprop"));
setOriginForNaryOp(I);
}
// Casts.
void visitSExtInst(SExtInst &I) {
IRBuilder<> IRB(&I);
setShadow(&I, IRB.CreateSExt(getShadow(&I, 0), I.getType(), "_msprop"));
setOrigin(&I, getOrigin(&I, 0));
}
void visitZExtInst(ZExtInst &I) {
IRBuilder<> IRB(&I);
setShadow(&I, IRB.CreateZExt(getShadow(&I, 0), I.getType(), "_msprop"));
setOrigin(&I, getOrigin(&I, 0));
}
void visitTruncInst(TruncInst &I) {
IRBuilder<> IRB(&I);
setShadow(&I, IRB.CreateTrunc(getShadow(&I, 0), I.getType(), "_msprop"));
setOrigin(&I, getOrigin(&I, 0));
}
void visitBitCastInst(BitCastInst &I) {
IRBuilder<> IRB(&I);
setShadow(&I, IRB.CreateBitCast(getShadow(&I, 0), getShadowTy(&I)));
setOrigin(&I, getOrigin(&I, 0));
}
void visitPtrToIntInst(PtrToIntInst &I) {
IRBuilder<> IRB(&I);
setShadow(&I, IRB.CreateIntCast(getShadow(&I, 0), getShadowTy(&I), false,
"_msprop_ptrtoint"));
setOrigin(&I, getOrigin(&I, 0));
}
void visitIntToPtrInst(IntToPtrInst &I) {
IRBuilder<> IRB(&I);
setShadow(&I, IRB.CreateIntCast(getShadow(&I, 0), getShadowTy(&I), false,
"_msprop_inttoptr"));
setOrigin(&I, getOrigin(&I, 0));
}
void visitFPToSIInst(CastInst& I) { handleShadowOr(I); }
void visitFPToUIInst(CastInst& I) { handleShadowOr(I); }
void visitSIToFPInst(CastInst& I) { handleShadowOr(I); }
void visitUIToFPInst(CastInst& I) { handleShadowOr(I); }
void visitFPExtInst(CastInst& I) { handleShadowOr(I); }
void visitFPTruncInst(CastInst& I) { handleShadowOr(I); }
/// \brief Propagate shadow for bitwise AND.
///
/// This code is exact, i.e. if, for example, a bit in the left argument
/// is defined and 0, then neither the value not definedness of the
/// corresponding bit in B don't affect the resulting shadow.
void visitAnd(BinaryOperator &I) {
IRBuilder<> IRB(&I);
// "And" of 0 and a poisoned value results in unpoisoned value.
// 1&1 => 1; 0&1 => 0; p&1 => p;
// 1&0 => 0; 0&0 => 0; p&0 => 0;
// 1&p => p; 0&p => 0; p&p => p;
// S = (S1 & S2) | (V1 & S2) | (S1 & V2)
Value *S1 = getShadow(&I, 0);
Value *S2 = getShadow(&I, 1);
Value *V1 = I.getOperand(0);
Value *V2 = I.getOperand(1);
if (V1->getType() != S1->getType()) {
V1 = IRB.CreateIntCast(V1, S1->getType(), false);
V2 = IRB.CreateIntCast(V2, S2->getType(), false);
}
Value *S1S2 = IRB.CreateAnd(S1, S2);
Value *V1S2 = IRB.CreateAnd(V1, S2);
Value *S1V2 = IRB.CreateAnd(S1, V2);
setShadow(&I, IRB.CreateOr(S1S2, IRB.CreateOr(V1S2, S1V2)));
setOriginForNaryOp(I);
}
void visitOr(BinaryOperator &I) {
IRBuilder<> IRB(&I);
// "Or" of 1 and a poisoned value results in unpoisoned value.
// 1|1 => 1; 0|1 => 1; p|1 => 1;
// 1|0 => 1; 0|0 => 0; p|0 => p;
// 1|p => 1; 0|p => p; p|p => p;
// S = (S1 & S2) | (~V1 & S2) | (S1 & ~V2)
Value *S1 = getShadow(&I, 0);
Value *S2 = getShadow(&I, 1);
Value *V1 = IRB.CreateNot(I.getOperand(0));
Value *V2 = IRB.CreateNot(I.getOperand(1));
if (V1->getType() != S1->getType()) {
V1 = IRB.CreateIntCast(V1, S1->getType(), false);
V2 = IRB.CreateIntCast(V2, S2->getType(), false);
}
Value *S1S2 = IRB.CreateAnd(S1, S2);
Value *V1S2 = IRB.CreateAnd(V1, S2);
Value *S1V2 = IRB.CreateAnd(S1, V2);
setShadow(&I, IRB.CreateOr(S1S2, IRB.CreateOr(V1S2, S1V2)));
setOriginForNaryOp(I);
}
/// \brief Propagate origin for an instruction.
///
/// This is a general case of origin propagation. For an Nary operation,
/// is set to the origin of an argument that is not entirely initialized.
/// If there is more than one such arguments, the rightmost of them is picked.
/// It does not matter which one is picked if all arguments are initialized.
void setOriginForNaryOp(Instruction &I) {
if (!ClTrackOrigins) return;
IRBuilder<> IRB(&I);
Value *Origin = getOrigin(&I, 0);
for (unsigned Op = 1, n = I.getNumOperands(); Op < n; ++Op) {
Value *S = convertToShadowTyNoVec(getShadow(&I, Op), IRB);
Origin = IRB.CreateSelect(IRB.CreateICmpNE(S, getCleanShadow(S)),
getOrigin(&I, Op), Origin);
}
setOrigin(&I, Origin);
}
/// \brief Propagate shadow for a binary operation.
///
/// Shadow = Shadow0 | Shadow1, all 3 must have the same type.
/// Bitwise OR is selected as an operation that will never lose even a bit of
/// poison.
void handleShadowOrBinary(Instruction &I) {
IRBuilder<> IRB(&I);
Value *Shadow0 = getShadow(&I, 0);
Value *Shadow1 = getShadow(&I, 1);
setShadow(&I, IRB.CreateOr(Shadow0, Shadow1, "_msprop"));
setOriginForNaryOp(I);
}
/// \brief Propagate shadow for arbitrary operation.
///
/// This is a general case of shadow propagation, used in all cases where we
/// don't know and/or care about what the operation actually does.
/// It converts all input shadow values to a common type (extending or
/// truncating as necessary), and bitwise OR's them.
///
/// This is much cheaper than inserting checks (i.e. requiring inputs to be
/// fully initialized), and less prone to false positives.
// FIXME: is the casting actually correct?
// FIXME: merge this with handleShadowOrBinary.
void handleShadowOr(Instruction &I) {
IRBuilder<> IRB(&I);
Value *Shadow = getShadow(&I, 0);
for (unsigned Op = 1, n = I.getNumOperands(); Op < n; ++Op)
Shadow = IRB.CreateOr(
Shadow, IRB.CreateIntCast(getShadow(&I, Op), Shadow->getType(), false),
"_msprop");
Shadow = IRB.CreateIntCast(Shadow, getShadowTy(&I), false);
setShadow(&I, Shadow);
setOriginForNaryOp(I);
}
void visitFAdd(BinaryOperator &I) { handleShadowOrBinary(I); }
void visitFSub(BinaryOperator &I) { handleShadowOrBinary(I); }
void visitFMul(BinaryOperator &I) { handleShadowOrBinary(I); }
void visitAdd(BinaryOperator &I) { handleShadowOrBinary(I); }
void visitSub(BinaryOperator &I) { handleShadowOrBinary(I); }
void visitXor(BinaryOperator &I) { handleShadowOrBinary(I); }
void visitMul(BinaryOperator &I) { handleShadowOrBinary(I); }
void handleDiv(Instruction &I) {
IRBuilder<> IRB(&I);
// Strict on the second argument.
insertCheck(I.getOperand(1), &I);
setShadow(&I, getShadow(&I, 0));
setOrigin(&I, getOrigin(&I, 0));
}
void visitUDiv(BinaryOperator &I) { handleDiv(I); }
void visitSDiv(BinaryOperator &I) { handleDiv(I); }
void visitFDiv(BinaryOperator &I) { handleDiv(I); }
void visitURem(BinaryOperator &I) { handleDiv(I); }
void visitSRem(BinaryOperator &I) { handleDiv(I); }
void visitFRem(BinaryOperator &I) { handleDiv(I); }
/// \brief Instrument == and != comparisons.
///
/// Sometimes the comparison result is known even if some of the bits of the
/// arguments are not.
void handleEqualityComparison(ICmpInst &I) {
IRBuilder<> IRB(&I);
Value *A = I.getOperand(0);
Value *B = I.getOperand(1);
Value *Sa = getShadow(A);
Value *Sb = getShadow(B);
if (A->getType()->isPointerTy())
A = IRB.CreatePointerCast(A, MS.IntptrTy);
if (B->getType()->isPointerTy())
B = IRB.CreatePointerCast(B, MS.IntptrTy);
// A == B <==> (C = A^B) == 0
// A != B <==> (C = A^B) != 0
// Sc = Sa | Sb
Value *C = IRB.CreateXor(A, B);
Value *Sc = IRB.CreateOr(Sa, Sb);
// Now dealing with i = (C == 0) comparison (or C != 0, does not matter now)
// Result is defined if one of the following is true
// * there is a defined 1 bit in C
// * C is fully defined
// Si = !(C & ~Sc) && Sc
Value *Zero = Constant::getNullValue(Sc->getType());
Value *MinusOne = Constant::getAllOnesValue(Sc->getType());
Value *Si =
IRB.CreateAnd(IRB.CreateICmpNE(Sc, Zero),
IRB.CreateICmpEQ(
IRB.CreateAnd(IRB.CreateXor(Sc, MinusOne), C), Zero));
Si->setName("_msprop_icmp");
setShadow(&I, Si);
setOriginForNaryOp(I);
}
/// \brief Instrument signed relational comparisons.
///
/// Handle (x<0) and (x>=0) comparisons (essentially, sign bit tests) by
/// propagating the highest bit of the shadow. Everything else is delegated
/// to handleShadowOr().
void handleSignedRelationalComparison(ICmpInst &I) {
Constant *constOp0 = dyn_cast<Constant>(I.getOperand(0));
Constant *constOp1 = dyn_cast<Constant>(I.getOperand(1));
Value* op = NULL;
CmpInst::Predicate pre = I.getPredicate();
if (constOp0 && constOp0->isNullValue() &&
(pre == CmpInst::ICMP_SGT || pre == CmpInst::ICMP_SLE)) {
op = I.getOperand(1);
} else if (constOp1 && constOp1->isNullValue() &&
(pre == CmpInst::ICMP_SLT || pre == CmpInst::ICMP_SGE)) {
op = I.getOperand(0);
}
if (op) {
IRBuilder<> IRB(&I);
Value* Shadow =
IRB.CreateICmpSLT(getShadow(op), getCleanShadow(op), "_msprop_icmpslt");
setShadow(&I, Shadow);
setOrigin(&I, getOrigin(op));
} else {
handleShadowOr(I);
}
}
void visitICmpInst(ICmpInst &I) {
if (ClHandleICmp && I.isEquality())
handleEqualityComparison(I);
else if (ClHandleICmp && I.isSigned() && I.isRelational())
handleSignedRelationalComparison(I);
else
handleShadowOr(I);
}
void visitFCmpInst(FCmpInst &I) {
handleShadowOr(I);
}
void handleShift(BinaryOperator &I) {
IRBuilder<> IRB(&I);
// If any of the S2 bits are poisoned, the whole thing is poisoned.
// Otherwise perform the same shift on S1.
Value *S1 = getShadow(&I, 0);
Value *S2 = getShadow(&I, 1);
Value *S2Conv = IRB.CreateSExt(IRB.CreateICmpNE(S2, getCleanShadow(S2)),
S2->getType());
Value *V2 = I.getOperand(1);
Value *Shift = IRB.CreateBinOp(I.getOpcode(), S1, V2);
setShadow(&I, IRB.CreateOr(Shift, S2Conv));
setOriginForNaryOp(I);
}
void visitShl(BinaryOperator &I) { handleShift(I); }
void visitAShr(BinaryOperator &I) { handleShift(I); }
void visitLShr(BinaryOperator &I) { handleShift(I); }
/// \brief Instrument llvm.memmove
///
/// At this point we don't know if llvm.memmove will be inlined or not.
/// If we don't instrument it and it gets inlined,
/// our interceptor will not kick in and we will lose the memmove.
/// If we instrument the call here, but it does not get inlined,
/// we will memove the shadow twice: which is bad in case
/// of overlapping regions. So, we simply lower the intrinsic to a call.
///
/// Similar situation exists for memcpy and memset.
void visitMemMoveInst(MemMoveInst &I) {
IRBuilder<> IRB(&I);
IRB.CreateCall3(
MS.MemmoveFn,
IRB.CreatePointerCast(I.getArgOperand(0), IRB.getInt8PtrTy()),
IRB.CreatePointerCast(I.getArgOperand(1), IRB.getInt8PtrTy()),
IRB.CreateIntCast(I.getArgOperand(2), MS.IntptrTy, false));
I.eraseFromParent();
}
// Similar to memmove: avoid copying shadow twice.
// This is somewhat unfortunate as it may slowdown small constant memcpys.
// FIXME: consider doing manual inline for small constant sizes and proper
// alignment.
void visitMemCpyInst(MemCpyInst &I) {
IRBuilder<> IRB(&I);
IRB.CreateCall3(
MS.MemcpyFn,
IRB.CreatePointerCast(I.getArgOperand(0), IRB.getInt8PtrTy()),
IRB.CreatePointerCast(I.getArgOperand(1), IRB.getInt8PtrTy()),
IRB.CreateIntCast(I.getArgOperand(2), MS.IntptrTy, false));
I.eraseFromParent();
}
// Same as memcpy.
void visitMemSetInst(MemSetInst &I) {
IRBuilder<> IRB(&I);
IRB.CreateCall3(
MS.MemsetFn,
IRB.CreatePointerCast(I.getArgOperand(0), IRB.getInt8PtrTy()),
IRB.CreateIntCast(I.getArgOperand(1), IRB.getInt32Ty(), false),
IRB.CreateIntCast(I.getArgOperand(2), MS.IntptrTy, false));
I.eraseFromParent();
}
void visitVAStartInst(VAStartInst &I) {
VAHelper->visitVAStartInst(I);
}
void visitVACopyInst(VACopyInst &I) {
VAHelper->visitVACopyInst(I);
}
void handleBswap(IntrinsicInst &I) {
IRBuilder<> IRB(&I);
Value *Op = I.getArgOperand(0);
Type *OpType = Op->getType();
Function *BswapFunc = Intrinsic::getDeclaration(
F.getParent(), Intrinsic::bswap, ArrayRef<Type*>(&OpType, 1));
setShadow(&I, IRB.CreateCall(BswapFunc, getShadow(Op)));
setOrigin(&I, getOrigin(Op));
}
void visitIntrinsicInst(IntrinsicInst &I) {
switch (I.getIntrinsicID()) {
case llvm::Intrinsic::bswap:
handleBswap(I); break;
default:
visitInstruction(I); break;
}
}
void visitCallSite(CallSite CS) {
Instruction &I = *CS.getInstruction();
assert((CS.isCall() || CS.isInvoke()) && "Unknown type of CallSite");
if (CS.isCall()) {
CallInst *Call = cast<CallInst>(&I);
// For inline asm, do the usual thing: check argument shadow and mark all
// outputs as clean. Note that any side effects of the inline asm that are
// not immediately visible in its constraints are not handled.
if (Call->isInlineAsm()) {
visitInstruction(I);
return;
}
// Allow only tail calls with the same types, otherwise
// we may have a false positive: shadow for a non-void RetVal
// will get propagated to a void RetVal.
if (Call->isTailCall() && Call->getType() != Call->getParent()->getType())
Call->setTailCall(false);
assert(!isa<IntrinsicInst>(&I) && "intrinsics are handled elsewhere");
// We are going to insert code that relies on the fact that the callee
// will become a non-readonly function after it is instrumented by us. To
// prevent this code from being optimized out, mark that function
// non-readonly in advance.
if (Function *Func = Call->getCalledFunction()) {
// Clear out readonly/readnone attributes.
AttrBuilder B;
B.addAttribute(Attributes::ReadOnly)
.addAttribute(Attributes::ReadNone);
Func->removeAttribute(AttributeSet::FunctionIndex,
Attributes::get(Func->getContext(), B));
}
}
IRBuilder<> IRB(&I);
unsigned ArgOffset = 0;
DEBUG(dbgs() << " CallSite: " << I << "\n");
for (CallSite::arg_iterator ArgIt = CS.arg_begin(), End = CS.arg_end();
ArgIt != End; ++ArgIt) {
Value *A = *ArgIt;
unsigned i = ArgIt - CS.arg_begin();
if (!A->getType()->isSized()) {
DEBUG(dbgs() << "Arg " << i << " is not sized: " << I << "\n");
continue;
}
unsigned Size = 0;
Value *Store = 0;
// Compute the Shadow for arg even if it is ByVal, because
// in that case getShadow() will copy the actual arg shadow to
// __msan_param_tls.
Value *ArgShadow = getShadow(A);
Value *ArgShadowBase = getShadowPtrForArgument(A, IRB, ArgOffset);
DEBUG(dbgs() << " Arg#" << i << ": " << *A <<
" Shadow: " << *ArgShadow << "\n");
if (CS.paramHasAttr(i + 1, Attributes::ByVal)) {
assert(A->getType()->isPointerTy() &&
"ByVal argument is not a pointer!");
Size = MS.TD->getTypeAllocSize(A->getType()->getPointerElementType());
unsigned Alignment = CS.getParamAlignment(i + 1);
Store = IRB.CreateMemCpy(ArgShadowBase,
getShadowPtr(A, Type::getInt8Ty(*MS.C), IRB),
Size, Alignment);
} else {
Size = MS.TD->getTypeAllocSize(A->getType());
Store = IRB.CreateAlignedStore(ArgShadow, ArgShadowBase,
kShadowTLSAlignment);
}
if (ClTrackOrigins)
IRB.CreateAlignedStore(getOrigin(A),
getOriginPtrForArgument(A, IRB, ArgOffset),
kShadowTLSAlignment);
assert(Size != 0 && Store != 0);
DEBUG(dbgs() << " Param:" << *Store << "\n");
ArgOffset += DataLayout::RoundUpAlignment(Size, 8);
}
DEBUG(dbgs() << " done with call args\n");
FunctionType *FT =
cast<FunctionType>(CS.getCalledValue()->getType()-> getContainedType(0));
if (FT->isVarArg()) {
VAHelper->visitCallSite(CS, IRB);
}
// Now, get the shadow for the RetVal.
if (!I.getType()->isSized()) return;
IRBuilder<> IRBBefore(&I);
// Untill we have full dynamic coverage, make sure the retval shadow is 0.
Value *Base = getShadowPtrForRetval(&I, IRBBefore);
IRBBefore.CreateAlignedStore(getCleanShadow(&I), Base, kShadowTLSAlignment);
Instruction *NextInsn = 0;
if (CS.isCall()) {
NextInsn = I.getNextNode();
} else {
BasicBlock *NormalDest = cast<InvokeInst>(&I)->getNormalDest();
if (!NormalDest->getSinglePredecessor()) {
// FIXME: this case is tricky, so we are just conservative here.
// Perhaps we need to split the edge between this BB and NormalDest,
// but a naive attempt to use SplitEdge leads to a crash.
setShadow(&I, getCleanShadow(&I));
setOrigin(&I, getCleanOrigin());
return;
}
NextInsn = NormalDest->getFirstInsertionPt();
assert(NextInsn &&
"Could not find insertion point for retval shadow load");
}
IRBuilder<> IRBAfter(NextInsn);
Value *RetvalShadow =
IRBAfter.CreateAlignedLoad(getShadowPtrForRetval(&I, IRBAfter),
kShadowTLSAlignment, "_msret");
setShadow(&I, RetvalShadow);
if (ClTrackOrigins)
setOrigin(&I, IRBAfter.CreateLoad(getOriginPtrForRetval(IRBAfter)));
}
void visitReturnInst(ReturnInst &I) {
IRBuilder<> IRB(&I);
if (Value *RetVal = I.getReturnValue()) {
// Set the shadow for the RetVal.
Value *Shadow = getShadow(RetVal);
Value *ShadowPtr = getShadowPtrForRetval(RetVal, IRB);
DEBUG(dbgs() << "Return: " << *Shadow << "\n" << *ShadowPtr << "\n");
IRB.CreateAlignedStore(Shadow, ShadowPtr, kShadowTLSAlignment);
if (ClTrackOrigins)
IRB.CreateStore(getOrigin(RetVal), getOriginPtrForRetval(IRB));
}
}
void visitPHINode(PHINode &I) {
IRBuilder<> IRB(&I);
ShadowPHINodes.push_back(&I);
setShadow(&I, IRB.CreatePHI(getShadowTy(&I), I.getNumIncomingValues(),
"_msphi_s"));
if (ClTrackOrigins)
setOrigin(&I, IRB.CreatePHI(MS.OriginTy, I.getNumIncomingValues(),
"_msphi_o"));
}
void visitAllocaInst(AllocaInst &I) {
setShadow(&I, getCleanShadow(&I));
if (!ClPoisonStack) return;
IRBuilder<> IRB(I.getNextNode());
uint64_t Size = MS.TD->getTypeAllocSize(I.getAllocatedType());
if (ClPoisonStackWithCall) {
IRB.CreateCall2(MS.MsanPoisonStackFn,
IRB.CreatePointerCast(&I, IRB.getInt8PtrTy()),
ConstantInt::get(MS.IntptrTy, Size));
} else {
Value *ShadowBase = getShadowPtr(&I, Type::getInt8PtrTy(*MS.C), IRB);
IRB.CreateMemSet(ShadowBase, IRB.getInt8(ClPoisonStackPattern),
Size, I.getAlignment());
}
if (ClTrackOrigins) {
setOrigin(&I, getCleanOrigin());
SmallString<2048> StackDescriptionStorage;
raw_svector_ostream StackDescription(StackDescriptionStorage);
// We create a string with a description of the stack allocation and
// pass it into __msan_set_alloca_origin.
// It will be printed by the run-time if stack-originated UMR is found.
// The first 4 bytes of the string are set to '----' and will be replaced
// by __msan_va_arg_overflow_size_tls at the first call.
StackDescription << "----" << I.getName() << "@" << F.getName();
Value *Descr =
createPrivateNonConstGlobalForString(*F.getParent(),
StackDescription.str());
IRB.CreateCall3(MS.MsanSetAllocaOriginFn,
IRB.CreatePointerCast(&I, IRB.getInt8PtrTy()),
ConstantInt::get(MS.IntptrTy, Size),
IRB.CreatePointerCast(Descr, IRB.getInt8PtrTy()));
}
}
void visitSelectInst(SelectInst& I) {
IRBuilder<> IRB(&I);
setShadow(&I, IRB.CreateSelect(I.getCondition(),
getShadow(I.getTrueValue()), getShadow(I.getFalseValue()),
"_msprop"));
if (ClTrackOrigins)
setOrigin(&I, IRB.CreateSelect(I.getCondition(),
getOrigin(I.getTrueValue()), getOrigin(I.getFalseValue())));
}
void visitLandingPadInst(LandingPadInst &I) {
// Do nothing.
// See http://code.google.com/p/memory-sanitizer/issues/detail?id=1
setShadow(&I, getCleanShadow(&I));
setOrigin(&I, getCleanOrigin());
}
void visitGetElementPtrInst(GetElementPtrInst &I) {
handleShadowOr(I);
}
void visitExtractValueInst(ExtractValueInst &I) {
IRBuilder<> IRB(&I);
Value *Agg = I.getAggregateOperand();
DEBUG(dbgs() << "ExtractValue: " << I << "\n");
Value *AggShadow = getShadow(Agg);
DEBUG(dbgs() << " AggShadow: " << *AggShadow << "\n");
Value *ResShadow = IRB.CreateExtractValue(AggShadow, I.getIndices());
DEBUG(dbgs() << " ResShadow: " << *ResShadow << "\n");
setShadow(&I, ResShadow);
setOrigin(&I, getCleanOrigin());
}
void visitInsertValueInst(InsertValueInst &I) {
IRBuilder<> IRB(&I);
DEBUG(dbgs() << "InsertValue: " << I << "\n");
Value *AggShadow = getShadow(I.getAggregateOperand());
Value *InsShadow = getShadow(I.getInsertedValueOperand());
DEBUG(dbgs() << " AggShadow: " << *AggShadow << "\n");
DEBUG(dbgs() << " InsShadow: " << *InsShadow << "\n");
Value *Res = IRB.CreateInsertValue(AggShadow, InsShadow, I.getIndices());
DEBUG(dbgs() << " Res: " << *Res << "\n");
setShadow(&I, Res);
setOrigin(&I, getCleanOrigin());
}
void dumpInst(Instruction &I) {
if (CallInst *CI = dyn_cast<CallInst>(&I)) {
errs() << "ZZZ call " << CI->getCalledFunction()->getName() << "\n";
} else {
errs() << "ZZZ " << I.getOpcodeName() << "\n";
}
errs() << "QQQ " << I << "\n";
}
void visitResumeInst(ResumeInst &I) {
DEBUG(dbgs() << "Resume: " << I << "\n");
// Nothing to do here.
}
void visitInstruction(Instruction &I) {
// Everything else: stop propagating and check for poisoned shadow.
if (ClDumpStrictInstructions)
dumpInst(I);
DEBUG(dbgs() << "DEFAULT: " << I << "\n");
for (size_t i = 0, n = I.getNumOperands(); i < n; i++)
insertCheck(I.getOperand(i), &I);
setShadow(&I, getCleanShadow(&I));
setOrigin(&I, getCleanOrigin());
}
};
/// \brief AMD64-specific implementation of VarArgHelper.
struct VarArgAMD64Helper : public VarArgHelper {
// An unfortunate workaround for asymmetric lowering of va_arg stuff.
// See a comment in visitCallSite for more details.
static const unsigned AMD64GpEndOffset = 48; // AMD64 ABI Draft 0.99.6 p3.5.7
static const unsigned AMD64FpEndOffset = 176;
Function &F;
MemorySanitizer &MS;
MemorySanitizerVisitor &MSV;
Value *VAArgTLSCopy;
Value *VAArgOverflowSize;
SmallVector<CallInst*, 16> VAStartInstrumentationList;
VarArgAMD64Helper(Function &F, MemorySanitizer &MS,
MemorySanitizerVisitor &MSV)
: F(F), MS(MS), MSV(MSV), VAArgTLSCopy(0), VAArgOverflowSize(0) { }
enum ArgKind { AK_GeneralPurpose, AK_FloatingPoint, AK_Memory };
ArgKind classifyArgument(Value* arg) {
// A very rough approximation of X86_64 argument classification rules.
Type *T = arg->getType();
if (T->isFPOrFPVectorTy() || T->isX86_MMXTy())
return AK_FloatingPoint;
if (T->isIntegerTy() && T->getPrimitiveSizeInBits() <= 64)
return AK_GeneralPurpose;
if (T->isPointerTy())
return AK_GeneralPurpose;
return AK_Memory;
}
// For VarArg functions, store the argument shadow in an ABI-specific format
// that corresponds to va_list layout.
// We do this because Clang lowers va_arg in the frontend, and this pass
// only sees the low level code that deals with va_list internals.
// A much easier alternative (provided that Clang emits va_arg instructions)
// would have been to associate each live instance of va_list with a copy of
// MSanParamTLS, and extract shadow on va_arg() call in the argument list
// order.
void visitCallSite(CallSite &CS, IRBuilder<> &IRB) {
unsigned GpOffset = 0;
unsigned FpOffset = AMD64GpEndOffset;
unsigned OverflowOffset = AMD64FpEndOffset;
for (CallSite::arg_iterator ArgIt = CS.arg_begin(), End = CS.arg_end();
ArgIt != End; ++ArgIt) {
Value *A = *ArgIt;
ArgKind AK = classifyArgument(A);
if (AK == AK_GeneralPurpose && GpOffset >= AMD64GpEndOffset)
AK = AK_Memory;
if (AK == AK_FloatingPoint && FpOffset >= AMD64FpEndOffset)
AK = AK_Memory;
Value *Base;
switch (AK) {
case AK_GeneralPurpose:
Base = getShadowPtrForVAArgument(A, IRB, GpOffset);
GpOffset += 8;
break;
case AK_FloatingPoint:
Base = getShadowPtrForVAArgument(A, IRB, FpOffset);
FpOffset += 16;
break;
case AK_Memory:
uint64_t ArgSize = MS.TD->getTypeAllocSize(A->getType());
Base = getShadowPtrForVAArgument(A, IRB, OverflowOffset);
OverflowOffset += DataLayout::RoundUpAlignment(ArgSize, 8);
}
IRB.CreateAlignedStore(MSV.getShadow(A), Base, kShadowTLSAlignment);
}
Constant *OverflowSize =
ConstantInt::get(IRB.getInt64Ty(), OverflowOffset - AMD64FpEndOffset);
IRB.CreateStore(OverflowSize, MS.VAArgOverflowSizeTLS);
}
/// \brief Compute the shadow address for a given va_arg.
Value *getShadowPtrForVAArgument(Value *A, IRBuilder<> &IRB,
int ArgOffset) {
Value *Base = IRB.CreatePointerCast(MS.VAArgTLS, MS.IntptrTy);
Base = IRB.CreateAdd(Base, ConstantInt::get(MS.IntptrTy, ArgOffset));
return IRB.CreateIntToPtr(Base, PointerType::get(MSV.getShadowTy(A), 0),
"_msarg");
}
void visitVAStartInst(VAStartInst &I) {
IRBuilder<> IRB(&I);
VAStartInstrumentationList.push_back(&I);
Value *VAListTag = I.getArgOperand(0);
Value *ShadowPtr = MSV.getShadowPtr(VAListTag, IRB.getInt8Ty(), IRB);
// Unpoison the whole __va_list_tag.
// FIXME: magic ABI constants.
IRB.CreateMemSet(ShadowPtr, Constant::getNullValue(IRB.getInt8Ty()),
/* size */24, /* alignment */16, false);
}
void visitVACopyInst(VACopyInst &I) {
IRBuilder<> IRB(&I);
Value *VAListTag = I.getArgOperand(0);
Value *ShadowPtr = MSV.getShadowPtr(VAListTag, IRB.getInt8Ty(), IRB);
// Unpoison the whole __va_list_tag.
// FIXME: magic ABI constants.
IRB.CreateMemSet(ShadowPtr, Constant::getNullValue(IRB.getInt8Ty()),
/* size */ 24, /* alignment */ 16, false);
}
void finalizeInstrumentation() {
assert(!VAArgOverflowSize && !VAArgTLSCopy &&
"finalizeInstrumentation called twice");
if (!VAStartInstrumentationList.empty()) {
// If there is a va_start in this function, make a backup copy of
// va_arg_tls somewhere in the function entry block.
IRBuilder<> IRB(F.getEntryBlock().getFirstNonPHI());
VAArgOverflowSize = IRB.CreateLoad(MS.VAArgOverflowSizeTLS);
Value *CopySize =
IRB.CreateAdd(ConstantInt::get(MS.IntptrTy, AMD64FpEndOffset),
VAArgOverflowSize);
VAArgTLSCopy = IRB.CreateAlloca(Type::getInt8Ty(*MS.C), CopySize);
IRB.CreateMemCpy(VAArgTLSCopy, MS.VAArgTLS, CopySize, 8);
}
// Instrument va_start.
// Copy va_list shadow from the backup copy of the TLS contents.
for (size_t i = 0, n = VAStartInstrumentationList.size(); i < n; i++) {
CallInst *OrigInst = VAStartInstrumentationList[i];
IRBuilder<> IRB(OrigInst->getNextNode());
Value *VAListTag = OrigInst->getArgOperand(0);
Value *RegSaveAreaPtrPtr =
IRB.CreateIntToPtr(
IRB.CreateAdd(IRB.CreatePtrToInt(VAListTag, MS.IntptrTy),
ConstantInt::get(MS.IntptrTy, 16)),
Type::getInt64PtrTy(*MS.C));
Value *RegSaveAreaPtr = IRB.CreateLoad(RegSaveAreaPtrPtr);
Value *RegSaveAreaShadowPtr =
MSV.getShadowPtr(RegSaveAreaPtr, IRB.getInt8Ty(), IRB);
IRB.CreateMemCpy(RegSaveAreaShadowPtr, VAArgTLSCopy,
AMD64FpEndOffset, 16);
Value *OverflowArgAreaPtrPtr =
IRB.CreateIntToPtr(
IRB.CreateAdd(IRB.CreatePtrToInt(VAListTag, MS.IntptrTy),
ConstantInt::get(MS.IntptrTy, 8)),
Type::getInt64PtrTy(*MS.C));
Value *OverflowArgAreaPtr = IRB.CreateLoad(OverflowArgAreaPtrPtr);
Value *OverflowArgAreaShadowPtr =
MSV.getShadowPtr(OverflowArgAreaPtr, IRB.getInt8Ty(), IRB);
Value *SrcPtr =
getShadowPtrForVAArgument(VAArgTLSCopy, IRB, AMD64FpEndOffset);
IRB.CreateMemCpy(OverflowArgAreaShadowPtr, SrcPtr, VAArgOverflowSize, 16);
}
}
};
VarArgHelper* CreateVarArgHelper(Function &Func, MemorySanitizer &Msan,
MemorySanitizerVisitor &Visitor) {
return new VarArgAMD64Helper(Func, Msan, Visitor);
}
} // namespace
bool MemorySanitizer::runOnFunction(Function &F) {
MemorySanitizerVisitor Visitor(F, *this);
// Clear out readonly/readnone attributes.
AttrBuilder B;
B.addAttribute(Attributes::ReadOnly)
.addAttribute(Attributes::ReadNone);
F.removeAttribute(AttributeSet::FunctionIndex,
Attributes::get(F.getContext(), B));
return Visitor.runOnFunction();
}
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