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Diffstat (limited to 'llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp | 947 |
1 files changed, 947 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp new file mode 100644 index 000000000000..f8fa9cad03b8 --- /dev/null +++ b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp @@ -0,0 +1,947 @@ +//===-- SanitizerCoverage.cpp - coverage instrumentation for sanitizers ---===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// Coverage instrumentation done on LLVM IR level, works with Sanitizers. +// +//===----------------------------------------------------------------------===// + +#include "llvm/Transforms/Instrumentation/SanitizerCoverage.h" +#include "llvm/ADT/ArrayRef.h" +#include "llvm/ADT/SmallVector.h" +#include "llvm/Analysis/EHPersonalities.h" +#include "llvm/Analysis/PostDominators.h" +#include "llvm/IR/CFG.h" +#include "llvm/IR/CallSite.h" +#include "llvm/IR/Constant.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/IR/DebugInfo.h" +#include "llvm/IR/Dominators.h" +#include "llvm/IR/Function.h" +#include "llvm/IR/GlobalVariable.h" +#include "llvm/IR/IRBuilder.h" +#include "llvm/IR/InlineAsm.h" +#include "llvm/IR/IntrinsicInst.h" +#include "llvm/IR/Intrinsics.h" +#include "llvm/IR/LLVMContext.h" +#include "llvm/IR/MDBuilder.h" +#include "llvm/IR/Mangler.h" +#include "llvm/IR/Module.h" +#include "llvm/IR/Type.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Transforms/Instrumentation.h" +#include "llvm/Transforms/Utils/BasicBlockUtils.h" +#include "llvm/Transforms/Utils/ModuleUtils.h" + +using namespace llvm; + +#define DEBUG_TYPE "sancov" + +static const char *const SanCovTracePCIndirName = + "__sanitizer_cov_trace_pc_indir"; +static const char *const SanCovTracePCName = "__sanitizer_cov_trace_pc"; +static const char *const SanCovTraceCmp1 = "__sanitizer_cov_trace_cmp1"; +static const char *const SanCovTraceCmp2 = "__sanitizer_cov_trace_cmp2"; +static const char *const SanCovTraceCmp4 = "__sanitizer_cov_trace_cmp4"; +static const char *const SanCovTraceCmp8 = "__sanitizer_cov_trace_cmp8"; +static const char *const SanCovTraceConstCmp1 = + "__sanitizer_cov_trace_const_cmp1"; +static const char *const SanCovTraceConstCmp2 = + "__sanitizer_cov_trace_const_cmp2"; +static const char *const SanCovTraceConstCmp4 = + "__sanitizer_cov_trace_const_cmp4"; +static const char *const SanCovTraceConstCmp8 = + "__sanitizer_cov_trace_const_cmp8"; +static const char *const SanCovTraceDiv4 = "__sanitizer_cov_trace_div4"; +static const char *const SanCovTraceDiv8 = "__sanitizer_cov_trace_div8"; +static const char *const SanCovTraceGep = "__sanitizer_cov_trace_gep"; +static const char *const SanCovTraceSwitchName = "__sanitizer_cov_trace_switch"; +static const char *const SanCovModuleCtorTracePcGuardName = + "sancov.module_ctor_trace_pc_guard"; +static const char *const SanCovModuleCtor8bitCountersName = + "sancov.module_ctor_8bit_counters"; +static const uint64_t SanCtorAndDtorPriority = 2; + +static const char *const SanCovTracePCGuardName = + "__sanitizer_cov_trace_pc_guard"; +static const char *const SanCovTracePCGuardInitName = + "__sanitizer_cov_trace_pc_guard_init"; +static const char *const SanCov8bitCountersInitName = + "__sanitizer_cov_8bit_counters_init"; +static const char *const SanCovPCsInitName = "__sanitizer_cov_pcs_init"; + +static const char *const SanCovGuardsSectionName = "sancov_guards"; +static const char *const SanCovCountersSectionName = "sancov_cntrs"; +static const char *const SanCovPCsSectionName = "sancov_pcs"; + +static const char *const SanCovLowestStackName = "__sancov_lowest_stack"; + +static cl::opt<int> ClCoverageLevel( + "sanitizer-coverage-level", + cl::desc("Sanitizer Coverage. 0: none, 1: entry block, 2: all blocks, " + "3: all blocks and critical edges"), + cl::Hidden, cl::init(0)); + +static cl::opt<bool> ClTracePC("sanitizer-coverage-trace-pc", + cl::desc("Experimental pc tracing"), cl::Hidden, + cl::init(false)); + +static cl::opt<bool> ClTracePCGuard("sanitizer-coverage-trace-pc-guard", + cl::desc("pc tracing with a guard"), + cl::Hidden, cl::init(false)); + +// If true, we create a global variable that contains PCs of all instrumented +// BBs, put this global into a named section, and pass this section's bounds +// to __sanitizer_cov_pcs_init. +// This way the coverage instrumentation does not need to acquire the PCs +// at run-time. Works with trace-pc-guard and inline-8bit-counters. +static cl::opt<bool> ClCreatePCTable("sanitizer-coverage-pc-table", + cl::desc("create a static PC table"), + cl::Hidden, cl::init(false)); + +static cl::opt<bool> + ClInline8bitCounters("sanitizer-coverage-inline-8bit-counters", + cl::desc("increments 8-bit counter for every edge"), + cl::Hidden, cl::init(false)); + +static cl::opt<bool> + ClCMPTracing("sanitizer-coverage-trace-compares", + cl::desc("Tracing of CMP and similar instructions"), + cl::Hidden, cl::init(false)); + +static cl::opt<bool> ClDIVTracing("sanitizer-coverage-trace-divs", + cl::desc("Tracing of DIV instructions"), + cl::Hidden, cl::init(false)); + +static cl::opt<bool> ClGEPTracing("sanitizer-coverage-trace-geps", + cl::desc("Tracing of GEP instructions"), + cl::Hidden, cl::init(false)); + +static cl::opt<bool> + ClPruneBlocks("sanitizer-coverage-prune-blocks", + cl::desc("Reduce the number of instrumented blocks"), + cl::Hidden, cl::init(true)); + +static cl::opt<bool> ClStackDepth("sanitizer-coverage-stack-depth", + cl::desc("max stack depth tracing"), + cl::Hidden, cl::init(false)); + +namespace { + +SanitizerCoverageOptions getOptions(int LegacyCoverageLevel) { + SanitizerCoverageOptions Res; + switch (LegacyCoverageLevel) { + case 0: + Res.CoverageType = SanitizerCoverageOptions::SCK_None; + break; + case 1: + Res.CoverageType = SanitizerCoverageOptions::SCK_Function; + break; + case 2: + Res.CoverageType = SanitizerCoverageOptions::SCK_BB; + break; + case 3: + Res.CoverageType = SanitizerCoverageOptions::SCK_Edge; + break; + case 4: + Res.CoverageType = SanitizerCoverageOptions::SCK_Edge; + Res.IndirectCalls = true; + break; + } + return Res; +} + +SanitizerCoverageOptions OverrideFromCL(SanitizerCoverageOptions Options) { + // Sets CoverageType and IndirectCalls. + SanitizerCoverageOptions CLOpts = getOptions(ClCoverageLevel); + Options.CoverageType = std::max(Options.CoverageType, CLOpts.CoverageType); + Options.IndirectCalls |= CLOpts.IndirectCalls; + Options.TraceCmp |= ClCMPTracing; + Options.TraceDiv |= ClDIVTracing; + Options.TraceGep |= ClGEPTracing; + Options.TracePC |= ClTracePC; + Options.TracePCGuard |= ClTracePCGuard; + Options.Inline8bitCounters |= ClInline8bitCounters; + Options.PCTable |= ClCreatePCTable; + Options.NoPrune |= !ClPruneBlocks; + Options.StackDepth |= ClStackDepth; + if (!Options.TracePCGuard && !Options.TracePC && + !Options.Inline8bitCounters && !Options.StackDepth) + Options.TracePCGuard = true; // TracePCGuard is default. + return Options; +} + +using DomTreeCallback = function_ref<const DominatorTree *(Function &F)>; +using PostDomTreeCallback = + function_ref<const PostDominatorTree *(Function &F)>; + +class ModuleSanitizerCoverage { +public: + ModuleSanitizerCoverage( + const SanitizerCoverageOptions &Options = SanitizerCoverageOptions()) + : Options(OverrideFromCL(Options)) {} + bool instrumentModule(Module &M, DomTreeCallback DTCallback, + PostDomTreeCallback PDTCallback); + +private: + void instrumentFunction(Function &F, DomTreeCallback DTCallback, + PostDomTreeCallback PDTCallback); + void InjectCoverageForIndirectCalls(Function &F, + ArrayRef<Instruction *> IndirCalls); + void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets); + void InjectTraceForDiv(Function &F, + ArrayRef<BinaryOperator *> DivTraceTargets); + void InjectTraceForGep(Function &F, + ArrayRef<GetElementPtrInst *> GepTraceTargets); + void InjectTraceForSwitch(Function &F, + ArrayRef<Instruction *> SwitchTraceTargets); + bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks, + bool IsLeafFunc = true); + GlobalVariable *CreateFunctionLocalArrayInSection(size_t NumElements, + Function &F, Type *Ty, + const char *Section); + GlobalVariable *CreatePCArray(Function &F, ArrayRef<BasicBlock *> AllBlocks); + void CreateFunctionLocalArrays(Function &F, ArrayRef<BasicBlock *> AllBlocks); + void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx, + bool IsLeafFunc = true); + Function *CreateInitCallsForSections(Module &M, const char *CtorName, + const char *InitFunctionName, Type *Ty, + const char *Section); + std::pair<Value *, Value *> CreateSecStartEnd(Module &M, const char *Section, + Type *Ty); + + void SetNoSanitizeMetadata(Instruction *I) { + I->setMetadata(I->getModule()->getMDKindID("nosanitize"), + MDNode::get(*C, None)); + } + + std::string getSectionName(const std::string &Section) const; + std::string getSectionStart(const std::string &Section) const; + std::string getSectionEnd(const std::string &Section) const; + FunctionCallee SanCovTracePCIndir; + FunctionCallee SanCovTracePC, SanCovTracePCGuard; + FunctionCallee SanCovTraceCmpFunction[4]; + FunctionCallee SanCovTraceConstCmpFunction[4]; + FunctionCallee SanCovTraceDivFunction[2]; + FunctionCallee SanCovTraceGepFunction; + FunctionCallee SanCovTraceSwitchFunction; + GlobalVariable *SanCovLowestStack; + InlineAsm *EmptyAsm; + Type *IntptrTy, *IntptrPtrTy, *Int64Ty, *Int64PtrTy, *Int32Ty, *Int32PtrTy, + *Int16Ty, *Int8Ty, *Int8PtrTy; + Module *CurModule; + std::string CurModuleUniqueId; + Triple TargetTriple; + LLVMContext *C; + const DataLayout *DL; + + GlobalVariable *FunctionGuardArray; // for trace-pc-guard. + GlobalVariable *Function8bitCounterArray; // for inline-8bit-counters. + GlobalVariable *FunctionPCsArray; // for pc-table. + SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed; + SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed; + + SanitizerCoverageOptions Options; +}; + +class ModuleSanitizerCoverageLegacyPass : public ModulePass { +public: + ModuleSanitizerCoverageLegacyPass( + const SanitizerCoverageOptions &Options = SanitizerCoverageOptions()) + : ModulePass(ID), Options(Options) { + initializeModuleSanitizerCoverageLegacyPassPass( + *PassRegistry::getPassRegistry()); + } + bool runOnModule(Module &M) override { + ModuleSanitizerCoverage ModuleSancov(Options); + auto DTCallback = [this](Function &F) -> const DominatorTree * { + return &this->getAnalysis<DominatorTreeWrapperPass>(F).getDomTree(); + }; + auto PDTCallback = [this](Function &F) -> const PostDominatorTree * { + return &this->getAnalysis<PostDominatorTreeWrapperPass>(F) + .getPostDomTree(); + }; + return ModuleSancov.instrumentModule(M, DTCallback, PDTCallback); + } + + static char ID; // Pass identification, replacement for typeid + StringRef getPassName() const override { return "ModuleSanitizerCoverage"; } + + void getAnalysisUsage(AnalysisUsage &AU) const override { + AU.addRequired<DominatorTreeWrapperPass>(); + AU.addRequired<PostDominatorTreeWrapperPass>(); + } + +private: + SanitizerCoverageOptions Options; +}; + +} // namespace + +PreservedAnalyses ModuleSanitizerCoveragePass::run(Module &M, + ModuleAnalysisManager &MAM) { + ModuleSanitizerCoverage ModuleSancov(Options); + auto &FAM = MAM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager(); + auto DTCallback = [&FAM](Function &F) -> const DominatorTree * { + return &FAM.getResult<DominatorTreeAnalysis>(F); + }; + auto PDTCallback = [&FAM](Function &F) -> const PostDominatorTree * { + return &FAM.getResult<PostDominatorTreeAnalysis>(F); + }; + if (ModuleSancov.instrumentModule(M, DTCallback, PDTCallback)) + return PreservedAnalyses::none(); + return PreservedAnalyses::all(); +} + +std::pair<Value *, Value *> +ModuleSanitizerCoverage::CreateSecStartEnd(Module &M, const char *Section, + Type *Ty) { + GlobalVariable *SecStart = + new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage, nullptr, + getSectionStart(Section)); + SecStart->setVisibility(GlobalValue::HiddenVisibility); + GlobalVariable *SecEnd = + new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage, + nullptr, getSectionEnd(Section)); + SecEnd->setVisibility(GlobalValue::HiddenVisibility); + IRBuilder<> IRB(M.getContext()); + Value *SecEndPtr = IRB.CreatePointerCast(SecEnd, Ty); + if (!TargetTriple.isOSBinFormatCOFF()) + return std::make_pair(IRB.CreatePointerCast(SecStart, Ty), SecEndPtr); + + // Account for the fact that on windows-msvc __start_* symbols actually + // point to a uint64_t before the start of the array. + auto SecStartI8Ptr = IRB.CreatePointerCast(SecStart, Int8PtrTy); + auto GEP = IRB.CreateGEP(Int8Ty, SecStartI8Ptr, + ConstantInt::get(IntptrTy, sizeof(uint64_t))); + return std::make_pair(IRB.CreatePointerCast(GEP, Ty), SecEndPtr); +} + +Function *ModuleSanitizerCoverage::CreateInitCallsForSections( + Module &M, const char *CtorName, const char *InitFunctionName, Type *Ty, + const char *Section) { + auto SecStartEnd = CreateSecStartEnd(M, Section, Ty); + auto SecStart = SecStartEnd.first; + auto SecEnd = SecStartEnd.second; + Function *CtorFunc; + std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions( + M, CtorName, InitFunctionName, {Ty, Ty}, {SecStart, SecEnd}); + assert(CtorFunc->getName() == CtorName); + + if (TargetTriple.supportsCOMDAT()) { + // Use comdat to dedup CtorFunc. + CtorFunc->setComdat(M.getOrInsertComdat(CtorName)); + appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc); + } else { + appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority); + } + + if (TargetTriple.isOSBinFormatCOFF()) { + // In COFF files, if the contructors are set as COMDAT (they are because + // COFF supports COMDAT) and the linker flag /OPT:REF (strip unreferenced + // functions and data) is used, the constructors get stripped. To prevent + // this, give the constructors weak ODR linkage and ensure the linker knows + // to include the sancov constructor. This way the linker can deduplicate + // the constructors but always leave one copy. + CtorFunc->setLinkage(GlobalValue::WeakODRLinkage); + appendToUsed(M, CtorFunc); + } + return CtorFunc; +} + +bool ModuleSanitizerCoverage::instrumentModule( + Module &M, DomTreeCallback DTCallback, PostDomTreeCallback PDTCallback) { + if (Options.CoverageType == SanitizerCoverageOptions::SCK_None) + return false; + C = &(M.getContext()); + DL = &M.getDataLayout(); + CurModule = &M; + CurModuleUniqueId = getUniqueModuleId(CurModule); + TargetTriple = Triple(M.getTargetTriple()); + FunctionGuardArray = nullptr; + Function8bitCounterArray = nullptr; + FunctionPCsArray = nullptr; + IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits()); + IntptrPtrTy = PointerType::getUnqual(IntptrTy); + Type *VoidTy = Type::getVoidTy(*C); + IRBuilder<> IRB(*C); + Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty()); + Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty()); + Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty()); + Int64Ty = IRB.getInt64Ty(); + Int32Ty = IRB.getInt32Ty(); + Int16Ty = IRB.getInt16Ty(); + Int8Ty = IRB.getInt8Ty(); + + SanCovTracePCIndir = + M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy); + // Make sure smaller parameters are zero-extended to i64 as required by the + // x86_64 ABI. + AttributeList SanCovTraceCmpZeroExtAL; + if (TargetTriple.getArch() == Triple::x86_64) { + SanCovTraceCmpZeroExtAL = + SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 0, Attribute::ZExt); + SanCovTraceCmpZeroExtAL = + SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 1, Attribute::ZExt); + } + + SanCovTraceCmpFunction[0] = + M.getOrInsertFunction(SanCovTraceCmp1, SanCovTraceCmpZeroExtAL, VoidTy, + IRB.getInt8Ty(), IRB.getInt8Ty()); + SanCovTraceCmpFunction[1] = + M.getOrInsertFunction(SanCovTraceCmp2, SanCovTraceCmpZeroExtAL, VoidTy, + IRB.getInt16Ty(), IRB.getInt16Ty()); + SanCovTraceCmpFunction[2] = + M.getOrInsertFunction(SanCovTraceCmp4, SanCovTraceCmpZeroExtAL, VoidTy, + IRB.getInt32Ty(), IRB.getInt32Ty()); + SanCovTraceCmpFunction[3] = + M.getOrInsertFunction(SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty); + + SanCovTraceConstCmpFunction[0] = M.getOrInsertFunction( + SanCovTraceConstCmp1, SanCovTraceCmpZeroExtAL, VoidTy, Int8Ty, Int8Ty); + SanCovTraceConstCmpFunction[1] = M.getOrInsertFunction( + SanCovTraceConstCmp2, SanCovTraceCmpZeroExtAL, VoidTy, Int16Ty, Int16Ty); + SanCovTraceConstCmpFunction[2] = M.getOrInsertFunction( + SanCovTraceConstCmp4, SanCovTraceCmpZeroExtAL, VoidTy, Int32Ty, Int32Ty); + SanCovTraceConstCmpFunction[3] = + M.getOrInsertFunction(SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty); + + { + AttributeList AL; + if (TargetTriple.getArch() == Triple::x86_64) + AL = AL.addParamAttribute(*C, 0, Attribute::ZExt); + SanCovTraceDivFunction[0] = + M.getOrInsertFunction(SanCovTraceDiv4, AL, VoidTy, IRB.getInt32Ty()); + } + SanCovTraceDivFunction[1] = + M.getOrInsertFunction(SanCovTraceDiv8, VoidTy, Int64Ty); + SanCovTraceGepFunction = + M.getOrInsertFunction(SanCovTraceGep, VoidTy, IntptrTy); + SanCovTraceSwitchFunction = + M.getOrInsertFunction(SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy); + + Constant *SanCovLowestStackConstant = + M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy); + SanCovLowestStack = dyn_cast<GlobalVariable>(SanCovLowestStackConstant); + if (!SanCovLowestStack) { + C->emitError(StringRef("'") + SanCovLowestStackName + + "' should not be declared by the user"); + return true; + } + SanCovLowestStack->setThreadLocalMode( + GlobalValue::ThreadLocalMode::InitialExecTLSModel); + if (Options.StackDepth && !SanCovLowestStack->isDeclaration()) + SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy)); + + // We insert an empty inline asm after cov callbacks to avoid callback merge. + EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false), + StringRef(""), StringRef(""), + /*hasSideEffects=*/true); + + SanCovTracePC = M.getOrInsertFunction(SanCovTracePCName, VoidTy); + SanCovTracePCGuard = + M.getOrInsertFunction(SanCovTracePCGuardName, VoidTy, Int32PtrTy); + + for (auto &F : M) + instrumentFunction(F, DTCallback, PDTCallback); + + Function *Ctor = nullptr; + + if (FunctionGuardArray) + Ctor = CreateInitCallsForSections(M, SanCovModuleCtorTracePcGuardName, + SanCovTracePCGuardInitName, Int32PtrTy, + SanCovGuardsSectionName); + if (Function8bitCounterArray) + Ctor = CreateInitCallsForSections(M, SanCovModuleCtor8bitCountersName, + SanCov8bitCountersInitName, Int8PtrTy, + SanCovCountersSectionName); + if (Ctor && Options.PCTable) { + auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrPtrTy); + FunctionCallee InitFunction = declareSanitizerInitFunction( + M, SanCovPCsInitName, {IntptrPtrTy, IntptrPtrTy}); + IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator()); + IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second}); + } + // We don't reference these arrays directly in any of our runtime functions, + // so we need to prevent them from being dead stripped. + if (TargetTriple.isOSBinFormatMachO()) + appendToUsed(M, GlobalsToAppendToUsed); + appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed); + return true; +} + +// True if block has successors and it dominates all of them. +static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) { + if (succ_begin(BB) == succ_end(BB)) + return false; + + for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) { + if (!DT->dominates(BB, SUCC)) + return false; + } + + return true; +} + +// True if block has predecessors and it postdominates all of them. +static bool isFullPostDominator(const BasicBlock *BB, + const PostDominatorTree *PDT) { + if (pred_begin(BB) == pred_end(BB)) + return false; + + for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) { + if (!PDT->dominates(BB, PRED)) + return false; + } + + return true; +} + +static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB, + const DominatorTree *DT, + const PostDominatorTree *PDT, + const SanitizerCoverageOptions &Options) { + // Don't insert coverage for blocks containing nothing but unreachable: we + // will never call __sanitizer_cov() for them, so counting them in + // NumberOfInstrumentedBlocks() might complicate calculation of code coverage + // percentage. Also, unreachable instructions frequently have no debug + // locations. + if (isa<UnreachableInst>(BB->getFirstNonPHIOrDbgOrLifetime())) + return false; + + // Don't insert coverage into blocks without a valid insertion point + // (catchswitch blocks). + if (BB->getFirstInsertionPt() == BB->end()) + return false; + + if (Options.NoPrune || &F.getEntryBlock() == BB) + return true; + + if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function && + &F.getEntryBlock() != BB) + return false; + + // Do not instrument full dominators, or full post-dominators with multiple + // predecessors. + return !isFullDominator(BB, DT) + && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor()); +} + + +// Returns true iff From->To is a backedge. +// A twist here is that we treat From->To as a backedge if +// * To dominates From or +// * To->UniqueSuccessor dominates From +static bool IsBackEdge(BasicBlock *From, BasicBlock *To, + const DominatorTree *DT) { + if (DT->dominates(To, From)) + return true; + if (auto Next = To->getUniqueSuccessor()) + if (DT->dominates(Next, From)) + return true; + return false; +} + +// Prunes uninteresting Cmp instrumentation: +// * CMP instructions that feed into loop backedge branch. +// +// Note that Cmp pruning is controlled by the same flag as the +// BB pruning. +static bool IsInterestingCmp(ICmpInst *CMP, const DominatorTree *DT, + const SanitizerCoverageOptions &Options) { + if (!Options.NoPrune) + if (CMP->hasOneUse()) + if (auto BR = dyn_cast<BranchInst>(CMP->user_back())) + for (BasicBlock *B : BR->successors()) + if (IsBackEdge(BR->getParent(), B, DT)) + return false; + return true; +} + +void ModuleSanitizerCoverage::instrumentFunction( + Function &F, DomTreeCallback DTCallback, PostDomTreeCallback PDTCallback) { + if (F.empty()) + return; + if (F.getName().find(".module_ctor") != std::string::npos) + return; // Should not instrument sanitizer init functions. + if (F.getName().startswith("__sanitizer_")) + return; // Don't instrument __sanitizer_* callbacks. + // Don't touch available_externally functions, their actual body is elewhere. + if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) + return; + // Don't instrument MSVC CRT configuration helpers. They may run before normal + // initialization. + if (F.getName() == "__local_stdio_printf_options" || + F.getName() == "__local_stdio_scanf_options") + return; + if (isa<UnreachableInst>(F.getEntryBlock().getTerminator())) + return; + // Don't instrument functions using SEH for now. Splitting basic blocks like + // we do for coverage breaks WinEHPrepare. + // FIXME: Remove this when SEH no longer uses landingpad pattern matching. + if (F.hasPersonalityFn() && + isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn()))) + return; + if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge) + SplitAllCriticalEdges(F, CriticalEdgeSplittingOptions().setIgnoreUnreachableDests()); + SmallVector<Instruction *, 8> IndirCalls; + SmallVector<BasicBlock *, 16> BlocksToInstrument; + SmallVector<Instruction *, 8> CmpTraceTargets; + SmallVector<Instruction *, 8> SwitchTraceTargets; + SmallVector<BinaryOperator *, 8> DivTraceTargets; + SmallVector<GetElementPtrInst *, 8> GepTraceTargets; + + const DominatorTree *DT = DTCallback(F); + const PostDominatorTree *PDT = PDTCallback(F); + bool IsLeafFunc = true; + + for (auto &BB : F) { + if (shouldInstrumentBlock(F, &BB, DT, PDT, Options)) + BlocksToInstrument.push_back(&BB); + for (auto &Inst : BB) { + if (Options.IndirectCalls) { + CallSite CS(&Inst); + if (CS && !CS.getCalledFunction()) + IndirCalls.push_back(&Inst); + } + if (Options.TraceCmp) { + if (ICmpInst *CMP = dyn_cast<ICmpInst>(&Inst)) + if (IsInterestingCmp(CMP, DT, Options)) + CmpTraceTargets.push_back(&Inst); + if (isa<SwitchInst>(&Inst)) + SwitchTraceTargets.push_back(&Inst); + } + if (Options.TraceDiv) + if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst)) + if (BO->getOpcode() == Instruction::SDiv || + BO->getOpcode() == Instruction::UDiv) + DivTraceTargets.push_back(BO); + if (Options.TraceGep) + if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst)) + GepTraceTargets.push_back(GEP); + if (Options.StackDepth) + if (isa<InvokeInst>(Inst) || + (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst))) + IsLeafFunc = false; + } + } + + InjectCoverage(F, BlocksToInstrument, IsLeafFunc); + InjectCoverageForIndirectCalls(F, IndirCalls); + InjectTraceForCmp(F, CmpTraceTargets); + InjectTraceForSwitch(F, SwitchTraceTargets); + InjectTraceForDiv(F, DivTraceTargets); + InjectTraceForGep(F, GepTraceTargets); +} + +GlobalVariable *ModuleSanitizerCoverage::CreateFunctionLocalArrayInSection( + size_t NumElements, Function &F, Type *Ty, const char *Section) { + ArrayType *ArrayTy = ArrayType::get(Ty, NumElements); + auto Array = new GlobalVariable( + *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage, + Constant::getNullValue(ArrayTy), "__sancov_gen_"); + + if (TargetTriple.supportsCOMDAT() && !F.isInterposable()) + if (auto Comdat = + GetOrCreateFunctionComdat(F, TargetTriple, CurModuleUniqueId)) + Array->setComdat(Comdat); + Array->setSection(getSectionName(Section)); + Array->setAlignment(Align(Ty->isPointerTy() + ? DL->getPointerSize() + : Ty->getPrimitiveSizeInBits() / 8)); + GlobalsToAppendToUsed.push_back(Array); + GlobalsToAppendToCompilerUsed.push_back(Array); + MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F)); + Array->addMetadata(LLVMContext::MD_associated, *MD); + + return Array; +} + +GlobalVariable * +ModuleSanitizerCoverage::CreatePCArray(Function &F, + ArrayRef<BasicBlock *> AllBlocks) { + size_t N = AllBlocks.size(); + assert(N); + SmallVector<Constant *, 32> PCs; + IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt()); + for (size_t i = 0; i < N; i++) { + if (&F.getEntryBlock() == AllBlocks[i]) { + PCs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy)); + PCs.push_back((Constant *)IRB.CreateIntToPtr( + ConstantInt::get(IntptrTy, 1), IntptrPtrTy)); + } else { + PCs.push_back((Constant *)IRB.CreatePointerCast( + BlockAddress::get(AllBlocks[i]), IntptrPtrTy)); + PCs.push_back((Constant *)IRB.CreateIntToPtr( + ConstantInt::get(IntptrTy, 0), IntptrPtrTy)); + } + } + auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, IntptrPtrTy, + SanCovPCsSectionName); + PCArray->setInitializer( + ConstantArray::get(ArrayType::get(IntptrPtrTy, N * 2), PCs)); + PCArray->setConstant(true); + + return PCArray; +} + +void ModuleSanitizerCoverage::CreateFunctionLocalArrays( + Function &F, ArrayRef<BasicBlock *> AllBlocks) { + if (Options.TracePCGuard) + FunctionGuardArray = CreateFunctionLocalArrayInSection( + AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName); + + if (Options.Inline8bitCounters) + Function8bitCounterArray = CreateFunctionLocalArrayInSection( + AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName); + + if (Options.PCTable) + FunctionPCsArray = CreatePCArray(F, AllBlocks); +} + +bool ModuleSanitizerCoverage::InjectCoverage(Function &F, + ArrayRef<BasicBlock *> AllBlocks, + bool IsLeafFunc) { + if (AllBlocks.empty()) return false; + CreateFunctionLocalArrays(F, AllBlocks); + for (size_t i = 0, N = AllBlocks.size(); i < N; i++) + InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc); + return true; +} + +// On every indirect call we call a run-time function +// __sanitizer_cov_indir_call* with two parameters: +// - callee address, +// - global cache array that contains CacheSize pointers (zero-initialized). +// The cache is used to speed up recording the caller-callee pairs. +// The address of the caller is passed implicitly via caller PC. +// CacheSize is encoded in the name of the run-time function. +void ModuleSanitizerCoverage::InjectCoverageForIndirectCalls( + Function &F, ArrayRef<Instruction *> IndirCalls) { + if (IndirCalls.empty()) + return; + assert(Options.TracePC || Options.TracePCGuard || Options.Inline8bitCounters); + for (auto I : IndirCalls) { + IRBuilder<> IRB(I); + CallSite CS(I); + Value *Callee = CS.getCalledValue(); + if (isa<InlineAsm>(Callee)) + continue; + IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy)); + } +} + +// For every switch statement we insert a call: +// __sanitizer_cov_trace_switch(CondValue, +// {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... }) + +void ModuleSanitizerCoverage::InjectTraceForSwitch( + Function &, ArrayRef<Instruction *> SwitchTraceTargets) { + for (auto I : SwitchTraceTargets) { + if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) { + IRBuilder<> IRB(I); + SmallVector<Constant *, 16> Initializers; + Value *Cond = SI->getCondition(); + if (Cond->getType()->getScalarSizeInBits() > + Int64Ty->getScalarSizeInBits()) + continue; + Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases())); + Initializers.push_back( + ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits())); + if (Cond->getType()->getScalarSizeInBits() < + Int64Ty->getScalarSizeInBits()) + Cond = IRB.CreateIntCast(Cond, Int64Ty, false); + for (auto It : SI->cases()) { + Constant *C = It.getCaseValue(); + if (C->getType()->getScalarSizeInBits() < + Int64Ty->getScalarSizeInBits()) + C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty); + Initializers.push_back(C); + } + llvm::sort(Initializers.begin() + 2, Initializers.end(), + [](const Constant *A, const Constant *B) { + return cast<ConstantInt>(A)->getLimitedValue() < + cast<ConstantInt>(B)->getLimitedValue(); + }); + ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size()); + GlobalVariable *GV = new GlobalVariable( + *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage, + ConstantArray::get(ArrayOfInt64Ty, Initializers), + "__sancov_gen_cov_switch_values"); + IRB.CreateCall(SanCovTraceSwitchFunction, + {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)}); + } + } +} + +void ModuleSanitizerCoverage::InjectTraceForDiv( + Function &, ArrayRef<BinaryOperator *> DivTraceTargets) { + for (auto BO : DivTraceTargets) { + IRBuilder<> IRB(BO); + Value *A1 = BO->getOperand(1); + if (isa<ConstantInt>(A1)) continue; + if (!A1->getType()->isIntegerTy()) + continue; + uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType()); + int CallbackIdx = TypeSize == 32 ? 0 : + TypeSize == 64 ? 1 : -1; + if (CallbackIdx < 0) continue; + auto Ty = Type::getIntNTy(*C, TypeSize); + IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx], + {IRB.CreateIntCast(A1, Ty, true)}); + } +} + +void ModuleSanitizerCoverage::InjectTraceForGep( + Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) { + for (auto GEP : GepTraceTargets) { + IRBuilder<> IRB(GEP); + for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I) + if (!isa<ConstantInt>(*I) && (*I)->getType()->isIntegerTy()) + IRB.CreateCall(SanCovTraceGepFunction, + {IRB.CreateIntCast(*I, IntptrTy, true)}); + } +} + +void ModuleSanitizerCoverage::InjectTraceForCmp( + Function &, ArrayRef<Instruction *> CmpTraceTargets) { + for (auto I : CmpTraceTargets) { + if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) { + IRBuilder<> IRB(ICMP); + Value *A0 = ICMP->getOperand(0); + Value *A1 = ICMP->getOperand(1); + if (!A0->getType()->isIntegerTy()) + continue; + uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType()); + int CallbackIdx = TypeSize == 8 ? 0 : + TypeSize == 16 ? 1 : + TypeSize == 32 ? 2 : + TypeSize == 64 ? 3 : -1; + if (CallbackIdx < 0) continue; + // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1); + auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx]; + bool FirstIsConst = isa<ConstantInt>(A0); + bool SecondIsConst = isa<ConstantInt>(A1); + // If both are const, then we don't need such a comparison. + if (FirstIsConst && SecondIsConst) continue; + // If only one is const, then make it the first callback argument. + if (FirstIsConst || SecondIsConst) { + CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx]; + if (SecondIsConst) + std::swap(A0, A1); + } + + auto Ty = Type::getIntNTy(*C, TypeSize); + IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true), + IRB.CreateIntCast(A1, Ty, true)}); + } + } +} + +void ModuleSanitizerCoverage::InjectCoverageAtBlock(Function &F, BasicBlock &BB, + size_t Idx, + bool IsLeafFunc) { + BasicBlock::iterator IP = BB.getFirstInsertionPt(); + bool IsEntryBB = &BB == &F.getEntryBlock(); + DebugLoc EntryLoc; + if (IsEntryBB) { + if (auto SP = F.getSubprogram()) + EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP); + // Keep static allocas and llvm.localescape calls in the entry block. Even + // if we aren't splitting the block, it's nice for allocas to be before + // calls. + IP = PrepareToSplitEntryBlock(BB, IP); + } else { + EntryLoc = IP->getDebugLoc(); + } + + IRBuilder<> IRB(&*IP); + IRB.SetCurrentDebugLocation(EntryLoc); + if (Options.TracePC) { + IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC. + IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge. + } + if (Options.TracePCGuard) { + auto GuardPtr = IRB.CreateIntToPtr( + IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy), + ConstantInt::get(IntptrTy, Idx * 4)), + Int32PtrTy); + IRB.CreateCall(SanCovTracePCGuard, GuardPtr); + IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge. + } + if (Options.Inline8bitCounters) { + auto CounterPtr = IRB.CreateGEP( + Function8bitCounterArray->getValueType(), Function8bitCounterArray, + {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)}); + auto Load = IRB.CreateLoad(Int8Ty, CounterPtr); + auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1)); + auto Store = IRB.CreateStore(Inc, CounterPtr); + SetNoSanitizeMetadata(Load); + SetNoSanitizeMetadata(Store); + } + if (Options.StackDepth && IsEntryBB && !IsLeafFunc) { + // Check stack depth. If it's the deepest so far, record it. + Module *M = F.getParent(); + Function *GetFrameAddr = Intrinsic::getDeclaration( + M, Intrinsic::frameaddress, + IRB.getInt8PtrTy(M->getDataLayout().getAllocaAddrSpace())); + auto FrameAddrPtr = + IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)}); + auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy); + auto LowestStack = IRB.CreateLoad(IntptrTy, SanCovLowestStack); + auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack); + auto ThenTerm = SplitBlockAndInsertIfThen(IsStackLower, &*IP, false); + IRBuilder<> ThenIRB(ThenTerm); + auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack); + SetNoSanitizeMetadata(LowestStack); + SetNoSanitizeMetadata(Store); + } +} + +std::string +ModuleSanitizerCoverage::getSectionName(const std::string &Section) const { + if (TargetTriple.isOSBinFormatCOFF()) { + if (Section == SanCovCountersSectionName) + return ".SCOV$CM"; + if (Section == SanCovPCsSectionName) + return ".SCOVP$M"; + return ".SCOV$GM"; // For SanCovGuardsSectionName. + } + if (TargetTriple.isOSBinFormatMachO()) + return "__DATA,__" + Section; + return "__" + Section; +} + +std::string +ModuleSanitizerCoverage::getSectionStart(const std::string &Section) const { + if (TargetTriple.isOSBinFormatMachO()) + return "\1section$start$__DATA$__" + Section; + return "__start___" + Section; +} + +std::string +ModuleSanitizerCoverage::getSectionEnd(const std::string &Section) const { + if (TargetTriple.isOSBinFormatMachO()) + return "\1section$end$__DATA$__" + Section; + return "__stop___" + Section; +} + +char ModuleSanitizerCoverageLegacyPass::ID = 0; +INITIALIZE_PASS_BEGIN(ModuleSanitizerCoverageLegacyPass, "sancov", + "Pass for instrumenting coverage on functions", false, + false) +INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) +INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass) +INITIALIZE_PASS_END(ModuleSanitizerCoverageLegacyPass, "sancov", + "Pass for instrumenting coverage on functions", false, + false) +ModulePass *llvm::createModuleSanitizerCoverageLegacyPassPass( + const SanitizerCoverageOptions &Options) { + return new ModuleSanitizerCoverageLegacyPass(Options); +} |