//===-- 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). /// /// Origin tracking. /// /// MemorySanitizer can track origins (allocation points) of all uninitialized /// values. This behavior is controlled with a flag (msan-track-origins) and is /// disabled by default. /// /// Origins are 4-byte values created and interpreted by the runtime library. /// They are stored in a second shadow mapping, one 4-byte value for 4 bytes /// of application memory. Propagation of origins is basically a bunch of /// "select" instructions that pick the origin of a dirty argument, if an /// instruction has one. /// /// Every 4 aligned, consecutive bytes of application memory have one origin /// value associated with them. If these bytes contain uninitialized data /// coming from 2 different allocations, the last store wins. Because of this, /// MemorySanitizer reports can show unrelated origins, but this is unlikely in /// practice. /// /// Origins are meaningless for fully initialized values, so MemorySanitizer /// avoids storing origin to memory when a fully initialized value is stored. /// This way it avoids needless overwritting origin of the 4-byte region on /// a short (i.e. 1 byte) clean store, and it is also good for performance. /// /// Atomic handling. /// /// Ideally, every atomic store of application value should update the /// corresponding shadow location in an atomic way. Unfortunately, atomic store /// of two disjoint locations can not be done without severe slowdown. /// /// Therefore, we implement an approximation that may err on the safe side. /// In this implementation, every atomically accessed location in the program /// may only change from (partially) uninitialized to fully initialized, but /// not the other way around. We load the shadow _after_ the application load, /// and we store the shadow _before_ the app store. Also, we always store clean /// shadow (if the application store is atomic). This way, if the store-load /// pair constitutes a happens-before arc, shadow store and load are correctly /// ordered such that the load will get either the value that was stored, or /// some later value (which is always clean). /// /// This does not work very well with Compare-And-Swap (CAS) and /// Read-Modify-Write (RMW) operations. To follow the above logic, CAS and RMW /// must store the new shadow before the app operation, and load the shadow /// after the app operation. Computers don't work this way. Current /// implementation ignores the load aspect of CAS/RMW, always returning a clean /// value. It implements the store part as a simple atomic store by storing a /// clean shadow. //===----------------------------------------------------------------------===// #define DEBUG_TYPE "msan" #include "llvm/Transforms/Instrumentation.h" #include "llvm/ADT/DepthFirstIterator.h" #include "llvm/ADT/SmallString.h" #include "llvm/ADT/SmallVector.h" #include "llvm/ADT/Triple.h" #include "llvm/ADT/ValueMap.h" #include "llvm/IR/DataLayout.h" #include "llvm/IR/Function.h" #include "llvm/IR/IRBuilder.h" #include "llvm/IR/InlineAsm.h" #include "llvm/IR/IntrinsicInst.h" #include "llvm/IR/LLVMContext.h" #include "llvm/IR/MDBuilder.h" #include "llvm/IR/Module.h" #include "llvm/IR/Type.h" #include "llvm/InstVisitor.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/Local.h" #include "llvm/Transforms/Utils/ModuleUtils.h" #include "llvm/Transforms/Utils/SpecialCaseList.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 unsigned kMinOriginAlignment = 4; static const unsigned kShadowTLSAlignment = 8; /// \brief Track origins of uninitialized values. /// /// Adds a section to MemorySanitizer report that points to the allocation /// (stack or heap) the uninitialized bits came from originally. static cl::opt ClTrackOrigins("msan-track-origins", cl::desc("Track origins (allocation sites) of poisoned memory"), cl::Hidden, cl::init(false)); static cl::opt ClKeepGoing("msan-keep-going", cl::desc("keep going after reporting a UMR"), cl::Hidden, cl::init(false)); static cl::opt ClPoisonStack("msan-poison-stack", cl::desc("poison uninitialized stack variables"), cl::Hidden, cl::init(true)); static cl::opt ClPoisonStackWithCall("msan-poison-stack-with-call", cl::desc("poison uninitialized stack variables with a call"), cl::Hidden, cl::init(false)); static cl::opt ClPoisonStackPattern("msan-poison-stack-pattern", cl::desc("poison uninitialized stack variables with the given patter"), cl::Hidden, cl::init(0xff)); static cl::opt ClPoisonUndef("msan-poison-undef", cl::desc("poison undef temps"), cl::Hidden, cl::init(true)); static cl::opt ClHandleICmp("msan-handle-icmp", cl::desc("propagate shadow through ICmpEQ and ICmpNE"), cl::Hidden, cl::init(true)); static cl::opt ClHandleICmpExact("msan-handle-icmp-exact", cl::desc("exact handling of relational integer ICmp"), cl::Hidden, cl::init(false)); static cl::opt 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 ClCheckAccessAddress("msan-check-access-address", cl::desc("report accesses through a pointer which has poisoned shadow"), cl::Hidden, cl::init(true)); static cl::opt ClDumpStrictInstructions("msan-dump-strict-instructions", cl::desc("print out instructions with default strict semantics"), cl::Hidden, cl::init(false)); static cl::opt ClBlacklistFile("msan-blacklist", cl::desc("File containing the list of functions where MemorySanitizer " "should not report bugs"), cl::Hidden); // Experimental. Wraps all indirect calls in the instrumented code with // a call to the given function. This is needed to assist the dynamic // helper tool (MSanDR) to regain control on transition between instrumented and // non-instrumented code. static cl::opt ClWrapIndirectCalls("msan-wrap-indirect-calls", cl::desc("Wrap indirect calls with a given function"), cl::Hidden); static cl::opt ClWrapIndirectCallsFast("msan-wrap-indirect-calls-fast", cl::desc("Do not wrap indirect calls with target in the same module"), cl::Hidden, cl::init(true)); 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(bool TrackOrigins = false, StringRef BlacklistFile = StringRef()) : FunctionPass(ID), TrackOrigins(TrackOrigins || ClTrackOrigins), TD(0), WarningFn(0), BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile : BlacklistFile), WrapIndirectCalls(!ClWrapIndirectCalls.empty()) {} 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); /// \brief Track origins (allocation points) of uninitialized values. bool TrackOrigins; 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; GlobalVariable *MsandrModuleStart; GlobalVariable *MsandrModuleEnd; /// \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 *MsanSetAllocaOrigin4Fn; /// \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 Path to blacklist file. SmallString<64> BlacklistFile; /// \brief The blacklist. OwningPtr BL; /// \brief An empty volatile inline asm that prevents callback merge. InlineAsm *EmptyAsm; bool WrapIndirectCalls; /// \brief Run-time wrapper for indirect calls. Value *IndirectCallWrapperFn; // Argument and return type of IndirectCallWrapperFn: void (*f)(void). Type *AnyFunctionPtrTy; friend struct MemorySanitizerVisitor; friend struct VarArgAMD64Helper; }; } // namespace char MemorySanitizer::ID = 0; INITIALIZE_PASS(MemorySanitizer, "msan", "MemorySanitizer: detects uninitialized reads.", false, false) FunctionPass *llvm::createMemorySanitizerPass(bool TrackOrigins, StringRef BlacklistFile) { return new MemorySanitizer(TrackOrigins, BlacklistFile); } /// \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); MsanSetAllocaOrigin4Fn = M.getOrInsertFunction( "__msan_set_alloca_origin4", IRB.getVoidTy(), IRB.getInt8PtrTy(), IntptrTy, IRB.getInt8PtrTy(), IntptrTy, 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::InitialExecTLSModel); RetvalOriginTLS = new GlobalVariable( M, OriginTy, false, GlobalVariable::ExternalLinkage, 0, "__msan_retval_origin_tls", 0, GlobalVariable::InitialExecTLSModel); ParamTLS = new GlobalVariable( M, ArrayType::get(IRB.getInt64Ty(), 1000), false, GlobalVariable::ExternalLinkage, 0, "__msan_param_tls", 0, GlobalVariable::InitialExecTLSModel); ParamOriginTLS = new GlobalVariable( M, ArrayType::get(OriginTy, 1000), false, GlobalVariable::ExternalLinkage, 0, "__msan_param_origin_tls", 0, GlobalVariable::InitialExecTLSModel); VAArgTLS = new GlobalVariable( M, ArrayType::get(IRB.getInt64Ty(), 1000), false, GlobalVariable::ExternalLinkage, 0, "__msan_va_arg_tls", 0, GlobalVariable::InitialExecTLSModel); VAArgOverflowSizeTLS = new GlobalVariable( M, IRB.getInt64Ty(), false, GlobalVariable::ExternalLinkage, 0, "__msan_va_arg_overflow_size_tls", 0, GlobalVariable::InitialExecTLSModel); OriginTLS = new GlobalVariable( M, IRB.getInt32Ty(), false, GlobalVariable::ExternalLinkage, 0, "__msan_origin_tls", 0, GlobalVariable::InitialExecTLSModel); // 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); if (WrapIndirectCalls) { AnyFunctionPtrTy = PointerType::getUnqual(FunctionType::get(IRB.getVoidTy(), false)); IndirectCallWrapperFn = M.getOrInsertFunction( ClWrapIndirectCalls, AnyFunctionPtrTy, AnyFunctionPtrTy, NULL); } if (ClWrapIndirectCallsFast) { MsandrModuleStart = new GlobalVariable( M, IRB.getInt32Ty(), false, GlobalValue::ExternalLinkage, 0, "__executable_start"); MsandrModuleStart->setVisibility(GlobalVariable::HiddenVisibility); MsandrModuleEnd = new GlobalVariable( M, IRB.getInt32Ty(), false, GlobalValue::ExternalLinkage, 0, "_end"); MsandrModuleEnd->setVisibility(GlobalVariable::HiddenVisibility); } } /// \brief Module-level initialization. /// /// inserts a call to __msan_init to the module's constructor list. bool MemorySanitizer::doInitialization(Module &M) { TD = getAnalysisIfAvailable(); if (!TD) return false; BL.reset(SpecialCaseList::createOrDie(BlacklistFile)); 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(M.getOrInsertFunction( "__msan_init", IRB.getVoidTy(), NULL)), 0); if (TrackOrigins) new GlobalVariable(M, IRB.getInt32Ty(), true, GlobalValue::WeakODRLinkage, IRB.getInt32(TrackOrigins), "__msan_track_origins"); if (ClKeepGoing) new GlobalVariable(M, IRB.getInt32Ty(), true, GlobalValue::WeakODRLinkage, IRB.getInt32(ClKeepGoing), "__msan_keep_going"); 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 { Function &F; MemorySanitizer &MS; SmallVector ShadowPHINodes, OriginPHINodes; ValueMap ShadowMap, OriginMap; OwningPtr VAHelper; // The following flags disable parts of MSan instrumentation based on // blacklist contents and command-line options. bool InsertChecks; bool LoadShadow; bool PoisonStack; bool PoisonUndef; bool CheckReturnValue; struct ShadowOriginAndInsertPoint { Value *Shadow; Value *Origin; Instruction *OrigIns; ShadowOriginAndInsertPoint(Value *S, Value *O, Instruction *I) : Shadow(S), Origin(O), OrigIns(I) { } ShadowOriginAndInsertPoint() : Shadow(0), Origin(0), OrigIns(0) { } }; SmallVector InstrumentationList; SmallVector StoreList; SmallVector IndirectCallList; MemorySanitizerVisitor(Function &F, MemorySanitizer &MS) : F(F), MS(MS), VAHelper(CreateVarArgHelper(F, MS, *this)) { bool SanitizeFunction = !MS.BL->isIn(F) && F.getAttributes().hasAttribute( AttributeSet::FunctionIndex, Attribute::SanitizeMemory); InsertChecks = SanitizeFunction; LoadShadow = SanitizeFunction; PoisonStack = SanitizeFunction && ClPoisonStack; PoisonUndef = SanitizeFunction && ClPoisonUndef; // FIXME: Consider using SpecialCaseList to specify a list of functions that // must always return fully initialized values. For now, we hardcode "main". CheckReturnValue = SanitizeFunction && (F.getName() == "main"); 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(StoreList[i]); IRBuilder<> IRB(&I); Value *Val = I.getValueOperand(); Value *Addr = I.getPointerOperand(); Value *Shadow = I.isAtomic() ? getCleanShadow(Val) : 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 (ClCheckAccessAddress) insertShadowCheck(Addr, &I); if (I.isAtomic()) I.setOrdering(addReleaseOrdering(I.getOrdering())); if (MS.TrackOrigins) { unsigned Alignment = std::max(kMinOriginAlignment, I.getAlignment()); if (ClStoreCleanOrigin || isa(Shadow->getType())) { IRB.CreateAlignedStore(getOrigin(Val), getOriginPtr(Addr, IRB), Alignment); } else { Value *ConvertedShadow = convertToShadowTyNoVec(Shadow, IRB); // 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 (isa(ConvertedShadow)) continue; Value *Cmp = IRB.CreateICmpNE(ConvertedShadow, getCleanShadow(ConvertedShadow), "_mscmp"); Instruction *CheckTerm = SplitBlockAndInsertIfThen(Cmp, &I, false, MS.OriginStoreWeights); IRBuilder<> IRBNew(CheckTerm); IRBNew.CreateAlignedStore(getOrigin(Val), getOriginPtr(Addr, IRBNew), Alignment); } } } } void materializeChecks() { for (size_t i = 0, n = InstrumentationList.size(); i < n; i++) { Value *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"); // See the comment in materializeStores(). if (isa(ConvertedShadow)) continue; Value *Cmp = IRB.CreateICmpNE(ConvertedShadow, getCleanShadow(ConvertedShadow), "_mscmp"); Instruction *CheckTerm = SplitBlockAndInsertIfThen( Cmp, OrigIns, /* Unreachable */ !ClKeepGoing, MS.ColdCallWeights); IRB.SetInsertPoint(CheckTerm); if (MS.TrackOrigins) { Value *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); } void materializeIndirectCalls() { for (size_t i = 0, n = IndirectCallList.size(); i < n; i++) { CallSite CS = IndirectCallList[i]; Instruction *I = CS.getInstruction(); BasicBlock *B = I->getParent(); IRBuilder<> IRB(I); Value *Fn0 = CS.getCalledValue(); Value *Fn = IRB.CreateBitCast(Fn0, MS.AnyFunctionPtrTy); if (ClWrapIndirectCallsFast) { // Check that call target is inside this module limits. Value *Start = IRB.CreateBitCast(MS.MsandrModuleStart, MS.AnyFunctionPtrTy); Value *End = IRB.CreateBitCast(MS.MsandrModuleEnd, MS.AnyFunctionPtrTy); Value *NotInThisModule = IRB.CreateOr(IRB.CreateICmpULT(Fn, Start), IRB.CreateICmpUGE(Fn, End)); PHINode *NewFnPhi = IRB.CreatePHI(Fn0->getType(), 2, "msandr.indirect_target"); Instruction *CheckTerm = SplitBlockAndInsertIfThen( NotInThisModule, NewFnPhi, /* Unreachable */ false, MS.ColdCallWeights); IRB.SetInsertPoint(CheckTerm); // Slow path: call wrapper function to possibly transform the call // target. Value *NewFn = IRB.CreateBitCast( IRB.CreateCall(MS.IndirectCallWrapperFn, Fn), Fn0->getType()); NewFnPhi->addIncoming(Fn0, B); NewFnPhi->addIncoming(NewFn, dyn_cast(NewFn)->getParent()); CS.setCalledFunction(NewFnPhi); } else { Value *NewFn = IRB.CreateBitCast( IRB.CreateCall(MS.IndirectCallWrapperFn, Fn), Fn0->getType()); CS.setCalledFunction(NewFn); } } } /// \brief Add MemorySanitizer instrumentation to a function. bool runOnFunction() { MS.initializeCallbacks(*F.getParent()); if (!MS.TD) return false; // In the presence of unreachable blocks, we may see Phi nodes with // incoming nodes from such blocks. Since InstVisitor skips unreachable // blocks, such nodes will not have any shadow value associated with them. // It's easier to remove unreachable blocks than deal with missing shadow. removeUnreachableBlocks(F); // 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 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(getShadow(PN)); PHINode *PNO = MS.TrackOrigins ? cast(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(); // Wrap indirect calls. materializeIndirectCalls(); 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(OrigTy)) return IT; if (VectorType *VT = dyn_cast(OrigTy)) { uint32_t EltSize = MS.TD->getTypeSizeInBits(VT->getElementType()); return VectorType::get(IntegerType::get(*MS.C, EltSize), VT->getNumElements()); } if (StructType *ST = dyn_cast(OrigTy)) { SmallVector 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->getTypeSizeInBits(OrigTy); return IntegerType::get(*MS.C, TypeSize); } /// \brief Flatten a vector type. Type *getShadowTyNoVec(Type *ty) { if (VectorType *vt = dyn_cast(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 (!MS.TrackOrigins) 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 (!MS.TrackOrigins) 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). Constant *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(ShadowTy) || isa(ShadowTy)) return Constant::getAllOnesValue(ShadowTy); StructType *ST = cast(ShadowTy); SmallVector 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 dirty shadow for a given value. Constant *getPoisonedShadow(Value *V) { Type *ShadowTy = getShadowTy(V); if (!ShadowTy) return 0; return getPoisonedShadow(ShadowTy); } /// \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(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(V)) { Value *AllOnes = PoisonUndef ? getPoisonedShadow(V) : getCleanShadow(V); DEBUG(dbgs() << "Undef: " << *U << " ==> " << *AllOnes << "\n"); (void)U; return AllOnes; } if (Argument *A = dyn_cast(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. // Figure out maximal valid memcpy alignment. unsigned ArgAlign = AI->getParamAlignment(); if (ArgAlign == 0) { Type *EltType = A->getType()->getPointerElementType(); ArgAlign = MS.TD->getABITypeAlignment(EltType); } unsigned CopyAlign = std::min(ArgAlign, kShadowTLSAlignment); Value *Cpy = EntryIRB.CreateMemCpy( getShadowPtr(V, EntryIRB.getInt8Ty(), EntryIRB), Base, Size, CopyAlign); DEBUG(dbgs() << " ByValCpy: " << *Cpy << "\n"); (void)Cpy; *ShadowPtr = getCleanShadow(V); } else { *ShadowPtr = EntryIRB.CreateAlignedLoad(Base, kShadowTLSAlignment); } DEBUG(dbgs() << " ARG: " << *AI << " ==> " << **ShadowPtr << "\n"); if (MS.TrackOrigins) { Value* OriginPtr = getOriginPtrForArgument(AI, EntryIRB, ArgOffset); setOrigin(A, EntryIRB.CreateLoad(OriginPtr)); } } ArgOffset += DataLayout::RoundUpAlignment(Size, kShadowTLSAlignment); } 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 (!MS.TrackOrigins) return 0; if (isa(V) || isa(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 shadow value is not 0. void insertShadowCheck(Value *Shadow, Value *Origin, Instruction *OrigIns) { assert(Shadow); if (!InsertChecks) return; #ifndef NDEBUG Type *ShadowTy = Shadow->getType(); assert((isa(ShadowTy) || isa(ShadowTy)) && "Can only insert checks for integer and vector shadow types"); #endif InstrumentationList.push_back( ShadowOriginAndInsertPoint(Shadow, Origin, OrigIns)); } /// \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 insertShadowCheck(Value *Val, Instruction *OrigIns) { assert(Val); Instruction *Shadow = dyn_cast_or_null(getShadow(Val)); if (!Shadow) return; Instruction *Origin = dyn_cast_or_null(getOrigin(Val)); insertShadowCheck(Shadow, Origin, OrigIns); } AtomicOrdering addReleaseOrdering(AtomicOrdering a) { switch (a) { case NotAtomic: return NotAtomic; case Unordered: case Monotonic: case Release: return Release; case Acquire: case AcquireRelease: return AcquireRelease; case SequentiallyConsistent: return SequentiallyConsistent; } llvm_unreachable("Unknown ordering"); } AtomicOrdering addAcquireOrdering(AtomicOrdering a) { switch (a) { case NotAtomic: return NotAtomic; case Unordered: case Monotonic: case Acquire: return Acquire; case Release: case AcquireRelease: return AcquireRelease; case SequentiallyConsistent: return SequentiallyConsistent; } llvm_unreachable("Unknown ordering"); } // ------------------- 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.getNextNode()); Type *ShadowTy = getShadowTy(&I); Value *Addr = I.getPointerOperand(); if (LoadShadow) { Value *ShadowPtr = getShadowPtr(Addr, ShadowTy, IRB); setShadow(&I, IRB.CreateAlignedLoad(ShadowPtr, I.getAlignment(), "_msld")); } else { setShadow(&I, getCleanShadow(&I)); } if (ClCheckAccessAddress) insertShadowCheck(I.getPointerOperand(), &I); if (I.isAtomic()) I.setOrdering(addAcquireOrdering(I.getOrdering())); if (MS.TrackOrigins) { if (LoadShadow) { unsigned Alignment = std::max(kMinOriginAlignment, I.getAlignment()); setOrigin(&I, IRB.CreateAlignedLoad(getOriginPtr(Addr, IRB), Alignment)); } else { setOrigin(&I, getCleanOrigin()); } } } /// \brief Instrument StoreInst /// /// Stores the corresponding shadow and (optionally) origin. /// Optionally, checks that the store address is fully defined. void visitStoreInst(StoreInst &I) { StoreList.push_back(&I); } void handleCASOrRMW(Instruction &I) { assert(isa(I) || isa(I)); IRBuilder<> IRB(&I); Value *Addr = I.getOperand(0); Value *ShadowPtr = getShadowPtr(Addr, I.getType(), IRB); if (ClCheckAccessAddress) insertShadowCheck(Addr, &I); // Only test the conditional argument of cmpxchg instruction. // The other argument can potentially be uninitialized, but we can not // detect this situation reliably without possible false positives. if (isa(I)) insertShadowCheck(I.getOperand(1), &I); IRB.CreateStore(getCleanShadow(&I), ShadowPtr); setShadow(&I, getCleanShadow(&I)); } void visitAtomicRMWInst(AtomicRMWInst &I) { handleCASOrRMW(I); I.setOrdering(addReleaseOrdering(I.getOrdering())); } void visitAtomicCmpXchgInst(AtomicCmpXchgInst &I) { handleCASOrRMW(I); I.setOrdering(addReleaseOrdering(I.getOrdering())); } // Vector manipulation. void visitExtractElementInst(ExtractElementInst &I) { insertShadowCheck(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) { insertShadowCheck(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) { insertShadowCheck(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 Default propagation of shadow and/or origin. /// /// This class implements the general case of shadow propagation, used in all /// cases where we don't know and/or don't 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. /// /// This class also implements the general case of origin propagation. For a /// Nary operation, result origin 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. template class Combiner { Value *Shadow; Value *Origin; IRBuilder<> &IRB; MemorySanitizerVisitor *MSV; public: Combiner(MemorySanitizerVisitor *MSV, IRBuilder<> &IRB) : Shadow(0), Origin(0), IRB(IRB), MSV(MSV) {} /// \brief Add a pair of shadow and origin values to the mix. Combiner &Add(Value *OpShadow, Value *OpOrigin) { if (CombineShadow) { assert(OpShadow); if (!Shadow) Shadow = OpShadow; else { OpShadow = MSV->CreateShadowCast(IRB, OpShadow, Shadow->getType()); Shadow = IRB.CreateOr(Shadow, OpShadow, "_msprop"); } } if (MSV->MS.TrackOrigins) { assert(OpOrigin); if (!Origin) { Origin = OpOrigin; } else { Value *FlatShadow = MSV->convertToShadowTyNoVec(OpShadow, IRB); Value *Cond = IRB.CreateICmpNE(FlatShadow, MSV->getCleanShadow(FlatShadow)); Origin = IRB.CreateSelect(Cond, OpOrigin, Origin); } } return *this; } /// \brief Add an application value to the mix. Combiner &Add(Value *V) { Value *OpShadow = MSV->getShadow(V); Value *OpOrigin = MSV->MS.TrackOrigins ? MSV->getOrigin(V) : 0; return Add(OpShadow, OpOrigin); } /// \brief Set the current combined values as the given instruction's shadow /// and origin. void Done(Instruction *I) { if (CombineShadow) { assert(Shadow); Shadow = MSV->CreateShadowCast(IRB, Shadow, MSV->getShadowTy(I)); MSV->setShadow(I, Shadow); } if (MSV->MS.TrackOrigins) { assert(Origin); MSV->setOrigin(I, Origin); } } }; typedef Combiner ShadowAndOriginCombiner; typedef Combiner OriginCombiner; /// \brief Propagate origin for arbitrary operation. void setOriginForNaryOp(Instruction &I) { if (!MS.TrackOrigins) return; IRBuilder<> IRB(&I); OriginCombiner OC(this, IRB); for (Instruction::op_iterator OI = I.op_begin(); OI != I.op_end(); ++OI) OC.Add(OI->get()); OC.Done(&I); } size_t VectorOrPrimitiveTypeSizeInBits(Type *Ty) { assert(!(Ty->isVectorTy() && Ty->getScalarType()->isPointerTy()) && "Vector of pointers is not a valid shadow type"); return Ty->isVectorTy() ? Ty->getVectorNumElements() * Ty->getScalarSizeInBits() : Ty->getPrimitiveSizeInBits(); } /// \brief Cast between two shadow types, extending or truncating as /// necessary. Value *CreateShadowCast(IRBuilder<> &IRB, Value *V, Type *dstTy, bool Signed = false) { Type *srcTy = V->getType(); if (dstTy->isIntegerTy() && srcTy->isIntegerTy()) return IRB.CreateIntCast(V, dstTy, Signed); if (dstTy->isVectorTy() && srcTy->isVectorTy() && dstTy->getVectorNumElements() == srcTy->getVectorNumElements()) return IRB.CreateIntCast(V, dstTy, Signed); size_t srcSizeInBits = VectorOrPrimitiveTypeSizeInBits(srcTy); size_t dstSizeInBits = VectorOrPrimitiveTypeSizeInBits(dstTy); Value *V1 = IRB.CreateBitCast(V, Type::getIntNTy(*MS.C, srcSizeInBits)); Value *V2 = IRB.CreateIntCast(V1, Type::getIntNTy(*MS.C, dstSizeInBits), Signed); return IRB.CreateBitCast(V2, dstTy); // TODO: handle struct types. } /// \brief Propagate shadow for arbitrary operation. void handleShadowOr(Instruction &I) { IRBuilder<> IRB(&I); ShadowAndOriginCombiner SC(this, IRB); for (Instruction::op_iterator OI = I.op_begin(); OI != I.op_end(); ++OI) SC.Add(OI->get()); SC.Done(&I); } void visitFAdd(BinaryOperator &I) { handleShadowOr(I); } void visitFSub(BinaryOperator &I) { handleShadowOr(I); } void visitFMul(BinaryOperator &I) { handleShadowOr(I); } void visitAdd(BinaryOperator &I) { handleShadowOr(I); } void visitSub(BinaryOperator &I) { handleShadowOr(I); } void visitXor(BinaryOperator &I) { handleShadowOr(I); } void visitMul(BinaryOperator &I) { handleShadowOr(I); } void handleDiv(Instruction &I) { IRBuilder<> IRB(&I); // Strict on the second argument. insertShadowCheck(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); // Get rid of pointers and vectors of pointers. // For ints (and vectors of ints), types of A and Sa match, // and this is a no-op. A = IRB.CreatePointerCast(A, Sa->getType()); B = IRB.CreatePointerCast(B, Sb->getType()); // 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 Build the lowest possible value of V, taking into account V's /// uninitialized bits. Value *getLowestPossibleValue(IRBuilder<> &IRB, Value *A, Value *Sa, bool isSigned) { if (isSigned) { // Split shadow into sign bit and other bits. Value *SaOtherBits = IRB.CreateLShr(IRB.CreateShl(Sa, 1), 1); Value *SaSignBit = IRB.CreateXor(Sa, SaOtherBits); // Maximise the undefined shadow bit, minimize other undefined bits. return IRB.CreateOr(IRB.CreateAnd(A, IRB.CreateNot(SaOtherBits)), SaSignBit); } else { // Minimize undefined bits. return IRB.CreateAnd(A, IRB.CreateNot(Sa)); } } /// \brief Build the highest possible value of V, taking into account V's /// uninitialized bits. Value *getHighestPossibleValue(IRBuilder<> &IRB, Value *A, Value *Sa, bool isSigned) { if (isSigned) { // Split shadow into sign bit and other bits. Value *SaOtherBits = IRB.CreateLShr(IRB.CreateShl(Sa, 1), 1); Value *SaSignBit = IRB.CreateXor(Sa, SaOtherBits); // Minimise the undefined shadow bit, maximise other undefined bits. return IRB.CreateOr(IRB.CreateAnd(A, IRB.CreateNot(SaSignBit)), SaOtherBits); } else { // Maximize undefined bits. return IRB.CreateOr(A, Sa); } } /// \brief Instrument relational comparisons. /// /// This function does exact shadow propagation for all relational /// comparisons of integers, pointers and vectors of those. /// FIXME: output seems suboptimal when one of the operands is a constant void handleRelationalComparisonExact(ICmpInst &I) { IRBuilder<> IRB(&I); Value *A = I.getOperand(0); Value *B = I.getOperand(1); Value *Sa = getShadow(A); Value *Sb = getShadow(B); // Get rid of pointers and vectors of pointers. // For ints (and vectors of ints), types of A and Sa match, // and this is a no-op. A = IRB.CreatePointerCast(A, Sa->getType()); B = IRB.CreatePointerCast(B, Sb->getType()); // Let [a0, a1] be the interval of possible values of A, taking into account // its undefined bits. Let [b0, b1] be the interval of possible values of B. // Then (A cmp B) is defined iff (a0 cmp b1) == (a1 cmp b0). bool IsSigned = I.isSigned(); Value *S1 = IRB.CreateICmp(I.getPredicate(), getLowestPossibleValue(IRB, A, Sa, IsSigned), getHighestPossibleValue(IRB, B, Sb, IsSigned)); Value *S2 = IRB.CreateICmp(I.getPredicate(), getHighestPossibleValue(IRB, A, Sa, IsSigned), getLowestPossibleValue(IRB, B, Sb, IsSigned)); Value *Si = IRB.CreateXor(S1, S2); 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(I.getOperand(0)); Constant *constOp1 = dyn_cast(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) { handleShadowOr(I); return; } if (I.isEquality()) { handleEqualityComparison(I); return; } assert(I.isRelational()); if (ClHandleICmpExact) { handleRelationalComparisonExact(I); return; } if (I.isSigned()) { handleSignedRelationalComparison(I); return; } assert(I.isUnsigned()); if ((isa(I.getOperand(0)) || isa(I.getOperand(1)))) { handleRelationalComparisonExact(I); return; } 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); } enum IntrinsicKind { IK_DoesNotAccessMemory, IK_OnlyReadsMemory, IK_WritesMemory }; static IntrinsicKind getIntrinsicKind(Intrinsic::ID iid) { const int DoesNotAccessMemory = IK_DoesNotAccessMemory; const int OnlyReadsArgumentPointees = IK_OnlyReadsMemory; const int OnlyReadsMemory = IK_OnlyReadsMemory; const int OnlyAccessesArgumentPointees = IK_WritesMemory; const int UnknownModRefBehavior = IK_WritesMemory; #define GET_INTRINSIC_MODREF_BEHAVIOR #define ModRefBehavior IntrinsicKind #include "llvm/IR/Intrinsics.gen" #undef ModRefBehavior #undef GET_INTRINSIC_MODREF_BEHAVIOR } /// \brief Handle vector store-like intrinsics. /// /// Instrument intrinsics that look like a simple SIMD store: writes memory, /// has 1 pointer argument and 1 vector argument, returns void. bool handleVectorStoreIntrinsic(IntrinsicInst &I) { IRBuilder<> IRB(&I); Value* Addr = I.getArgOperand(0); Value *Shadow = getShadow(&I, 1); Value *ShadowPtr = getShadowPtr(Addr, Shadow->getType(), IRB); // We don't know the pointer alignment (could be unaligned SSE store!). // Have to assume to worst case. IRB.CreateAlignedStore(Shadow, ShadowPtr, 1); if (ClCheckAccessAddress) insertShadowCheck(Addr, &I); // FIXME: use ClStoreCleanOrigin // FIXME: factor out common code from materializeStores if (MS.TrackOrigins) IRB.CreateStore(getOrigin(&I, 1), getOriginPtr(Addr, IRB)); return true; } /// \brief Handle vector load-like intrinsics. /// /// Instrument intrinsics that look like a simple SIMD load: reads memory, /// has 1 pointer argument, returns a vector. bool handleVectorLoadIntrinsic(IntrinsicInst &I) { IRBuilder<> IRB(&I); Value *Addr = I.getArgOperand(0); Type *ShadowTy = getShadowTy(&I); if (LoadShadow) { Value *ShadowPtr = getShadowPtr(Addr, ShadowTy, IRB); // We don't know the pointer alignment (could be unaligned SSE load!). // Have to assume to worst case. setShadow(&I, IRB.CreateAlignedLoad(ShadowPtr, 1, "_msld")); } else { setShadow(&I, getCleanShadow(&I)); } if (ClCheckAccessAddress) insertShadowCheck(Addr, &I); if (MS.TrackOrigins) { if (LoadShadow) setOrigin(&I, IRB.CreateLoad(getOriginPtr(Addr, IRB))); else setOrigin(&I, getCleanOrigin()); } return true; } /// \brief Handle (SIMD arithmetic)-like intrinsics. /// /// Instrument intrinsics with any number of arguments of the same type, /// equal to the return type. The type should be simple (no aggregates or /// pointers; vectors are fine). /// Caller guarantees that this intrinsic does not access memory. bool maybeHandleSimpleNomemIntrinsic(IntrinsicInst &I) { Type *RetTy = I.getType(); if (!(RetTy->isIntOrIntVectorTy() || RetTy->isFPOrFPVectorTy() || RetTy->isX86_MMXTy())) return false; unsigned NumArgOperands = I.getNumArgOperands(); for (unsigned i = 0; i < NumArgOperands; ++i) { Type *Ty = I.getArgOperand(i)->getType(); if (Ty != RetTy) return false; } IRBuilder<> IRB(&I); ShadowAndOriginCombiner SC(this, IRB); for (unsigned i = 0; i < NumArgOperands; ++i) SC.Add(I.getArgOperand(i)); SC.Done(&I); return true; } /// \brief Heuristically instrument unknown intrinsics. /// /// The main purpose of this code is to do something reasonable with all /// random intrinsics we might encounter, most importantly - SIMD intrinsics. /// We recognize several classes of intrinsics by their argument types and /// ModRefBehaviour and apply special intrumentation when we are reasonably /// sure that we know what the intrinsic does. /// /// We special-case intrinsics where this approach fails. See llvm.bswap /// handling as an example of that. bool handleUnknownIntrinsic(IntrinsicInst &I) { unsigned NumArgOperands = I.getNumArgOperands(); if (NumArgOperands == 0) return false; Intrinsic::ID iid = I.getIntrinsicID(); IntrinsicKind IK = getIntrinsicKind(iid); bool OnlyReadsMemory = IK == IK_OnlyReadsMemory; bool WritesMemory = IK == IK_WritesMemory; assert(!(OnlyReadsMemory && WritesMemory)); if (NumArgOperands == 2 && I.getArgOperand(0)->getType()->isPointerTy() && I.getArgOperand(1)->getType()->isVectorTy() && I.getType()->isVoidTy() && WritesMemory) { // This looks like a vector store. return handleVectorStoreIntrinsic(I); } if (NumArgOperands == 1 && I.getArgOperand(0)->getType()->isPointerTy() && I.getType()->isVectorTy() && OnlyReadsMemory) { // This looks like a vector load. return handleVectorLoadIntrinsic(I); } if (!OnlyReadsMemory && !WritesMemory) if (maybeHandleSimpleNomemIntrinsic(I)) return true; // FIXME: detect and handle SSE maskstore/maskload return false; } 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(&OpType, 1)); setShadow(&I, IRB.CreateCall(BswapFunc, getShadow(Op))); setOrigin(&I, getOrigin(Op)); } // \brief Instrument vector convert instrinsic. // // This function instruments intrinsics like cvtsi2ss: // %Out = int_xxx_cvtyyy(%ConvertOp) // or // %Out = int_xxx_cvtyyy(%CopyOp, %ConvertOp) // Intrinsic converts \p NumUsedElements elements of \p ConvertOp to the same // number \p Out elements, and (if has 2 arguments) copies the rest of the // elements from \p CopyOp. // In most cases conversion involves floating-point value which may trigger a // hardware exception when not fully initialized. For this reason we require // \p ConvertOp[0:NumUsedElements] to be fully initialized and trap otherwise. // We copy the shadow of \p CopyOp[NumUsedElements:] to \p // Out[NumUsedElements:]. This means that intrinsics without \p CopyOp always // return a fully initialized value. void handleVectorConvertIntrinsic(IntrinsicInst &I, int NumUsedElements) { IRBuilder<> IRB(&I); Value *CopyOp, *ConvertOp; switch (I.getNumArgOperands()) { case 2: CopyOp = I.getArgOperand(0); ConvertOp = I.getArgOperand(1); break; case 1: ConvertOp = I.getArgOperand(0); CopyOp = NULL; break; default: llvm_unreachable("Cvt intrinsic with unsupported number of arguments."); } // The first *NumUsedElements* elements of ConvertOp are converted to the // same number of output elements. The rest of the output is copied from // CopyOp, or (if not available) filled with zeroes. // Combine shadow for elements of ConvertOp that are used in this operation, // and insert a check. // FIXME: consider propagating shadow of ConvertOp, at least in the case of // int->any conversion. Value *ConvertShadow = getShadow(ConvertOp); Value *AggShadow = 0; if (ConvertOp->getType()->isVectorTy()) { AggShadow = IRB.CreateExtractElement( ConvertShadow, ConstantInt::get(IRB.getInt32Ty(), 0)); for (int i = 1; i < NumUsedElements; ++i) { Value *MoreShadow = IRB.CreateExtractElement( ConvertShadow, ConstantInt::get(IRB.getInt32Ty(), i)); AggShadow = IRB.CreateOr(AggShadow, MoreShadow); } } else { AggShadow = ConvertShadow; } assert(AggShadow->getType()->isIntegerTy()); insertShadowCheck(AggShadow, getOrigin(ConvertOp), &I); // Build result shadow by zero-filling parts of CopyOp shadow that come from // ConvertOp. if (CopyOp) { assert(CopyOp->getType() == I.getType()); assert(CopyOp->getType()->isVectorTy()); Value *ResultShadow = getShadow(CopyOp); Type *EltTy = ResultShadow->getType()->getVectorElementType(); for (int i = 0; i < NumUsedElements; ++i) { ResultShadow = IRB.CreateInsertElement( ResultShadow, ConstantInt::getNullValue(EltTy), ConstantInt::get(IRB.getInt32Ty(), i)); } setShadow(&I, ResultShadow); setOrigin(&I, getOrigin(CopyOp)); } else { setShadow(&I, getCleanShadow(&I)); } } void visitIntrinsicInst(IntrinsicInst &I) { switch (I.getIntrinsicID()) { case llvm::Intrinsic::bswap: handleBswap(I); break; case llvm::Intrinsic::x86_avx512_cvtsd2usi64: case llvm::Intrinsic::x86_avx512_cvtsd2usi: case llvm::Intrinsic::x86_avx512_cvtss2usi64: case llvm::Intrinsic::x86_avx512_cvtss2usi: case llvm::Intrinsic::x86_avx512_cvttss2usi64: case llvm::Intrinsic::x86_avx512_cvttss2usi: case llvm::Intrinsic::x86_avx512_cvttsd2usi64: case llvm::Intrinsic::x86_avx512_cvttsd2usi: case llvm::Intrinsic::x86_avx512_cvtusi2sd: case llvm::Intrinsic::x86_avx512_cvtusi2ss: case llvm::Intrinsic::x86_avx512_cvtusi642sd: case llvm::Intrinsic::x86_avx512_cvtusi642ss: case llvm::Intrinsic::x86_sse2_cvtsd2si64: case llvm::Intrinsic::x86_sse2_cvtsd2si: case llvm::Intrinsic::x86_sse2_cvtsd2ss: case llvm::Intrinsic::x86_sse2_cvtsi2sd: case llvm::Intrinsic::x86_sse2_cvtsi642sd: case llvm::Intrinsic::x86_sse2_cvtss2sd: case llvm::Intrinsic::x86_sse2_cvttsd2si64: case llvm::Intrinsic::x86_sse2_cvttsd2si: case llvm::Intrinsic::x86_sse_cvtsi2ss: case llvm::Intrinsic::x86_sse_cvtsi642ss: case llvm::Intrinsic::x86_sse_cvtss2si64: case llvm::Intrinsic::x86_sse_cvtss2si: case llvm::Intrinsic::x86_sse_cvttss2si64: case llvm::Intrinsic::x86_sse_cvttss2si: handleVectorConvertIntrinsic(I, 1); break; case llvm::Intrinsic::x86_sse2_cvtdq2pd: case llvm::Intrinsic::x86_sse2_cvtps2pd: case llvm::Intrinsic::x86_sse_cvtps2pi: case llvm::Intrinsic::x86_sse_cvttps2pi: handleVectorConvertIntrinsic(I, 2); break; default: if (!handleUnknownIntrinsic(I)) 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(&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(&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(Attribute::ReadOnly) .addAttribute(Attribute::ReadNone); Func->removeAttributes(AttributeSet::FunctionIndex, AttributeSet::get(Func->getContext(), AttributeSet::FunctionIndex, B)); } } IRBuilder<> IRB(&I); if (MS.WrapIndirectCalls && !CS.getCalledFunction()) IndirectCallList.push_back(CS); 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, Attribute::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 (MS.TrackOrigins) IRB.CreateStore(getOrigin(A), getOriginPtrForArgument(A, IRB, ArgOffset)); (void)Store; 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(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); // Until 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(&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 (MS.TrackOrigins) setOrigin(&I, IRBAfter.CreateLoad(getOriginPtrForRetval(IRBAfter))); } void visitReturnInst(ReturnInst &I) { IRBuilder<> IRB(&I); Value *RetVal = I.getReturnValue(); if (!RetVal) return; Value *ShadowPtr = getShadowPtrForRetval(RetVal, IRB); if (CheckReturnValue) { insertShadowCheck(RetVal, &I); Value *Shadow = getCleanShadow(RetVal); IRB.CreateAlignedStore(Shadow, ShadowPtr, kShadowTLSAlignment); } else { Value *Shadow = getShadow(RetVal); IRB.CreateAlignedStore(Shadow, ShadowPtr, kShadowTLSAlignment); // FIXME: make it conditional if ClStoreCleanOrigin==0 if (MS.TrackOrigins) 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 (MS.TrackOrigins) setOrigin(&I, IRB.CreatePHI(MS.OriginTy, I.getNumIncomingValues(), "_msphi_o")); } void visitAllocaInst(AllocaInst &I) { setShadow(&I, getCleanShadow(&I)); IRBuilder<> IRB(I.getNextNode()); uint64_t Size = MS.TD->getTypeAllocSize(I.getAllocatedType()); if (PoisonStack && 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); Value *PoisonValue = IRB.getInt8(PoisonStack ? ClPoisonStackPattern : 0); IRB.CreateMemSet(ShadowBase, PoisonValue, Size, I.getAlignment()); } if (PoisonStack && MS.TrackOrigins) { 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.CreateCall4(MS.MsanSetAllocaOrigin4Fn, IRB.CreatePointerCast(&I, IRB.getInt8PtrTy()), ConstantInt::get(MS.IntptrTy, Size), IRB.CreatePointerCast(Descr, IRB.getInt8PtrTy()), IRB.CreatePointerCast(&F, MS.IntptrTy)); } } void visitSelectInst(SelectInst& I) { IRBuilder<> IRB(&I); // a = select b, c, d Value *S = IRB.CreateSelect(I.getCondition(), getShadow(I.getTrueValue()), getShadow(I.getFalseValue())); if (I.getType()->isAggregateType()) { // To avoid "sign extending" i1 to an arbitrary aggregate type, we just do // an extra "select". This results in much more compact IR. // Sa = select Sb, poisoned, (select b, Sc, Sd) S = IRB.CreateSelect(getShadow(I.getCondition()), getPoisonedShadow(getShadowTy(I.getType())), S, "_msprop_select_agg"); } else { // Sa = (sext Sb) | (select b, Sc, Sd) S = IRB.CreateOr(S, CreateShadowCast(IRB, getShadow(I.getCondition()), S->getType(), true), "_msprop_select"); } setShadow(&I, S); if (MS.TrackOrigins) { // Origins are always i32, so any vector conditions must be flattened. // FIXME: consider tracking vector origins for app vectors? Value *Cond = I.getCondition(); Value *CondShadow = getShadow(Cond); if (Cond->getType()->isVectorTy()) { Type *FlatTy = getShadowTyNoVec(Cond->getType()); Cond = IRB.CreateICmpNE(IRB.CreateBitCast(Cond, FlatTy), ConstantInt::getNullValue(FlatTy)); CondShadow = IRB.CreateICmpNE(IRB.CreateBitCast(CondShadow, FlatTy), ConstantInt::getNullValue(FlatTy)); } // a = select b, c, d // Oa = Sb ? Ob : (b ? Oc : Od) setOrigin(&I, IRB.CreateSelect( CondShadow, getOrigin(I.getCondition()), IRB.CreateSelect(Cond, 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); setOriginForNaryOp(I); } 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); setOriginForNaryOp(I); } void dumpInst(Instruction &I) { if (CallInst *CI = dyn_cast(&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++) insertShadowCheck(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 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 */8, 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 */8, 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 = IRB.CreateConstGEP1_32(VAArgTLSCopy, AMD64FpEndOffset); IRB.CreateMemCpy(OverflowArgAreaShadowPtr, SrcPtr, VAArgOverflowSize, 16); } } }; /// \brief A no-op implementation of VarArgHelper. struct VarArgNoOpHelper : public VarArgHelper { VarArgNoOpHelper(Function &F, MemorySanitizer &MS, MemorySanitizerVisitor &MSV) {} void visitCallSite(CallSite &CS, IRBuilder<> &IRB) {} void visitVAStartInst(VAStartInst &I) {} void visitVACopyInst(VACopyInst &I) {} void finalizeInstrumentation() {} }; VarArgHelper *CreateVarArgHelper(Function &Func, MemorySanitizer &Msan, MemorySanitizerVisitor &Visitor) { // VarArg handling is only implemented on AMD64. False positives are possible // on other platforms. llvm::Triple TargetTriple(Func.getParent()->getTargetTriple()); if (TargetTriple.getArch() == llvm::Triple::x86_64) return new VarArgAMD64Helper(Func, Msan, Visitor); else return new VarArgNoOpHelper(Func, Msan, Visitor); } } // namespace bool MemorySanitizer::runOnFunction(Function &F) { MemorySanitizerVisitor Visitor(F, *this); // Clear out readonly/readnone attributes. AttrBuilder B; B.addAttribute(Attribute::ReadOnly) .addAttribute(Attribute::ReadNone); F.removeAttributes(AttributeSet::FunctionIndex, AttributeSet::get(F.getContext(), AttributeSet::FunctionIndex, B)); return Visitor.runOnFunction(); }