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llvm-project/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp

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//===-- SanitizerCoverage.cpp - coverage instrumentation for sanitizers ---===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Coverage instrumentation that works with AddressSanitizer
// and potentially with other Sanitizers.
//
// We create a Guard variable with the same linkage
// as the function and inject this code into the entry block (SCK_Function)
// or all blocks (SCK_BB):
// if (Guard < 0) {
// __sanitizer_cov(&Guard);
// }
// The accesses to Guard are atomic. The rest of the logic is
// in __sanitizer_cov (it's fine to call it more than once).
//
// With SCK_Edge we also split critical edges this effectively
// instrumenting all edges.
//
// This coverage implementation provides very limited data:
// it only tells if a given function (block) was ever executed. No counters.
// But for many use cases this is what we need and the added slowdown small.
//
//===----------------------------------------------------------------------===//
#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/DataLayout.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InlineAsm.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/MDBuilder.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/Scalar.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"
using namespace llvm;
#define DEBUG_TYPE "sancov"
static const char *const SanCovModuleInitName = "__sanitizer_cov_module_init";
static const char *const SanCovName = "__sanitizer_cov";
static const char *const SanCovWithCheckName = "__sanitizer_cov_with_check";
static const char *const SanCovIndirCallName = "__sanitizer_cov_indir_call16";
static const char *const SanCovTracePCIndirName =
"__sanitizer_cov_trace_pc_indir";
static const char *const SanCovTraceEnterName =
"__sanitizer_cov_trace_func_enter";
static const char *const SanCovTraceBBName =
"__sanitizer_cov_trace_basic_block";
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 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 SanCovModuleCtorName = "sancov.module_ctor";
static const uint64_t SanCtorAndDtorPriority = 2;
static const char *const SanCovTracePCGuardSection = "__sancov_guards";
static const char *const SanCovTracePCGuardName =
"__sanitizer_cov_trace_pc_guard";
static const char *const SanCovTracePCGuardInitName =
"__sanitizer_cov_trace_pc_guard_init";
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, "
"4: above plus indirect calls"),
cl::Hidden, cl::init(0));
static cl::opt<unsigned> ClCoverageBlockThreshold(
"sanitizer-coverage-block-threshold",
cl::desc("Use a callback with a guard check inside it if there are"
" more than this number of blocks."),
cl::Hidden, cl::init(0));
static cl::opt<bool>
ClExperimentalTracing("sanitizer-coverage-experimental-tracing",
cl::desc("Experimental basic-block tracing: insert "
"callbacks at every basic block"),
cl::Hidden, cl::init(false));
static cl::opt<bool> ClExperimentalTracePC("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));
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));
// Experimental 8-bit counters used as an additional search heuristic during
// coverage-guided fuzzing.
// The counters are not thread-friendly:
// - contention on these counters may cause significant slowdown;
// - the counter updates are racy and the results may be inaccurate.
// They are also inaccurate due to 8-bit integer overflow.
static cl::opt<bool> ClUse8bitCounters("sanitizer-coverage-8bit-counters",
cl::desc("Experimental 8-bit counters"),
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.TraceBB |= ClExperimentalTracing;
Options.TraceCmp |= ClCMPTracing;
Options.TraceDiv |= ClDIVTracing;
Options.TraceGep |= ClGEPTracing;
Options.Use8bitCounters |= ClUse8bitCounters;
Options.TracePC |= ClExperimentalTracePC;
Options.TracePCGuard |= ClTracePCGuard;
return Options;
}
class SanitizerCoverageModule : public ModulePass {
public:
SanitizerCoverageModule(
const SanitizerCoverageOptions &Options = SanitizerCoverageOptions())
: ModulePass(ID), Options(OverrideFromCL(Options)) {
initializeSanitizerCoverageModulePass(*PassRegistry::getPassRegistry());
}
bool runOnModule(Module &M) override;
bool runOnFunction(Function &F);
static char ID; // Pass identification, replacement for typeid
StringRef getPassName() const override { return "SanitizerCoverageModule"; }
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<PostDominatorTreeWrapperPass>();
}
private:
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);
void CreateFunctionGuardArray(size_t NumGuards, Function &F);
void SetNoSanitizeMetadata(Instruction *I);
void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx,
bool UseCalls);
unsigned NumberOfInstrumentedBlocks() {
return SanCovFunction->getNumUses() +
SanCovWithCheckFunction->getNumUses() + SanCovTraceBB->getNumUses() +
SanCovTraceEnter->getNumUses();
}
Function *SanCovFunction;
Function *SanCovWithCheckFunction;
Function *SanCovIndirCallFunction, *SanCovTracePCIndir;
Function *SanCovTraceEnter, *SanCovTraceBB, *SanCovTracePC, *SanCovTracePCGuard;
Function *SanCovTraceCmpFunction[4];
Function *SanCovTraceDivFunction[2];
Function *SanCovTraceGepFunction;
Function *SanCovTraceSwitchFunction;
InlineAsm *EmptyAsm;
Type *IntptrTy, *IntptrPtrTy, *Int64Ty, *Int64PtrTy, *Int32Ty, *Int32PtrTy;
Module *CurModule;
LLVMContext *C;
const DataLayout *DL;
GlobalVariable *GuardArray;
GlobalVariable *FunctionGuardArray; // for trace-pc-guard.
GlobalVariable *EightBitCounterArray;
bool HasSancovGuardsSection;
SanitizerCoverageOptions Options;
};
} // namespace
bool SanitizerCoverageModule::runOnModule(Module &M) {
if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
return false;
C = &(M.getContext());
DL = &M.getDataLayout();
CurModule = &M;
HasSancovGuardsSection = false;
IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
IntptrPtrTy = PointerType::getUnqual(IntptrTy);
Type *VoidTy = Type::getVoidTy(*C);
IRBuilder<> IRB(*C);
Type *Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty());
Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
Int64Ty = IRB.getInt64Ty();
Int32Ty = IRB.getInt32Ty();
SanCovFunction = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(SanCovName, VoidTy, Int32PtrTy, nullptr));
SanCovWithCheckFunction = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(SanCovWithCheckName, VoidTy, Int32PtrTy, nullptr));
SanCovTracePCIndir = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy, nullptr));
SanCovIndirCallFunction =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
SanCovIndirCallName, VoidTy, IntptrTy, IntptrTy, nullptr));
SanCovTraceCmpFunction[0] =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
SanCovTraceCmp1, VoidTy, IRB.getInt8Ty(), IRB.getInt8Ty(), nullptr));
SanCovTraceCmpFunction[1] = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(SanCovTraceCmp2, VoidTy, IRB.getInt16Ty(),
IRB.getInt16Ty(), nullptr));
SanCovTraceCmpFunction[2] = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(SanCovTraceCmp4, VoidTy, IRB.getInt32Ty(),
IRB.getInt32Ty(), nullptr));
SanCovTraceCmpFunction[3] =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty, nullptr));
SanCovTraceDivFunction[0] =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
SanCovTraceDiv4, VoidTy, IRB.getInt32Ty(), nullptr));
SanCovTraceDivFunction[1] =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
SanCovTraceDiv8, VoidTy, Int64Ty, nullptr));
SanCovTraceGepFunction =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
SanCovTraceGep, VoidTy, IntptrTy, nullptr));
SanCovTraceSwitchFunction =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy, nullptr));
// 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 = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(SanCovTracePCName, VoidTy, nullptr));
SanCovTracePCGuard = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
SanCovTracePCGuardName, VoidTy, Int32PtrTy, nullptr));
SanCovTraceEnter = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(SanCovTraceEnterName, VoidTy, Int32PtrTy, nullptr));
SanCovTraceBB = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(SanCovTraceBBName, VoidTy, Int32PtrTy, nullptr));
// At this point we create a dummy array of guards because we don't
// know how many elements we will need.
Type *Int32Ty = IRB.getInt32Ty();
Type *Int8Ty = IRB.getInt8Ty();
if (!Options.TracePCGuard)
GuardArray =
new GlobalVariable(M, Int32Ty, false, GlobalValue::ExternalLinkage,
nullptr, "__sancov_gen_cov_tmp");
if (Options.Use8bitCounters)
EightBitCounterArray =
new GlobalVariable(M, Int8Ty, false, GlobalVariable::ExternalLinkage,
nullptr, "__sancov_gen_cov_tmp");
for (auto &F : M)
runOnFunction(F);
auto N = NumberOfInstrumentedBlocks();
GlobalVariable *RealGuardArray = nullptr;
if (!Options.TracePCGuard) {
// Now we know how many elements we need. Create an array of guards
// with one extra element at the beginning for the size.
Type *Int32ArrayNTy = ArrayType::get(Int32Ty, N + 1);
RealGuardArray = new GlobalVariable(
M, Int32ArrayNTy, false, GlobalValue::PrivateLinkage,
Constant::getNullValue(Int32ArrayNTy), "__sancov_gen_cov");
// Replace the dummy array with the real one.
GuardArray->replaceAllUsesWith(
IRB.CreatePointerCast(RealGuardArray, Int32PtrTy));
GuardArray->eraseFromParent();
}
GlobalVariable *RealEightBitCounterArray;
if (Options.Use8bitCounters) {
// Make sure the array is 16-aligned.
static const int CounterAlignment = 16;
Type *Int8ArrayNTy = ArrayType::get(Int8Ty, alignTo(N, CounterAlignment));
RealEightBitCounterArray = new GlobalVariable(
M, Int8ArrayNTy, false, GlobalValue::PrivateLinkage,
Constant::getNullValue(Int8ArrayNTy), "__sancov_gen_cov_counter");
RealEightBitCounterArray->setAlignment(CounterAlignment);
EightBitCounterArray->replaceAllUsesWith(
IRB.CreatePointerCast(RealEightBitCounterArray, Int8PtrTy));
EightBitCounterArray->eraseFromParent();
}
// Create variable for module (compilation unit) name
Constant *ModNameStrConst =
ConstantDataArray::getString(M.getContext(), M.getName(), true);
GlobalVariable *ModuleName = new GlobalVariable(
M, ModNameStrConst->getType(), true, GlobalValue::PrivateLinkage,
ModNameStrConst, "__sancov_gen_modname");
if (Options.TracePCGuard) {
if (HasSancovGuardsSection) {
Function *CtorFunc;
std::string SectionName(SanCovTracePCGuardSection);
GlobalVariable *Bounds[2];
const char *Prefix[2] = {"__start_", "__stop_"};
for (int i = 0; i < 2; i++) {
Bounds[i] = new GlobalVariable(M, Int32PtrTy, false,
GlobalVariable::ExternalLinkage, nullptr,
Prefix[i] + SectionName);
Bounds[i]->setVisibility(GlobalValue::HiddenVisibility);
}
std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
M, SanCovModuleCtorName, SanCovTracePCGuardInitName,
{Int32PtrTy, Int32PtrTy},
{IRB.CreatePointerCast(Bounds[0], Int32PtrTy),
IRB.CreatePointerCast(Bounds[1], Int32PtrTy)});
appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
}
} else if (!Options.TracePC) {
Function *CtorFunc;
std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
M, SanCovModuleCtorName, SanCovModuleInitName,
{Int32PtrTy, IntptrTy, Int8PtrTy, Int8PtrTy},
{IRB.CreatePointerCast(RealGuardArray, Int32PtrTy),
ConstantInt::get(IntptrTy, N),
Options.Use8bitCounters
? IRB.CreatePointerCast(RealEightBitCounterArray, Int8PtrTy)
: Constant::getNullValue(Int8PtrTy),
IRB.CreatePointerCast(ModuleName, Int8PtrTy)});
appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
}
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) {
// Don't insert coverage for unreachable blocks: 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->getTerminator()))
return false;
if (!ClPruneBlocks || &F.getEntryBlock() == BB)
return true;
return !(isFullDominator(BB, DT) || isFullPostDominator(BB, PDT));
}
bool SanitizerCoverageModule::runOnFunction(Function &F) {
if (F.empty())
return false;
if (F.getName().find(".module_ctor") != std::string::npos)
return false; // Should not instrument sanitizer init functions.
if (F.getName().startswith("__sanitizer_"))
return false; // Don't instrument __sanitizer_* callbacks.
// 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 false;
// 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 false;
if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge)
SplitAllCriticalEdges(F);
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 =
&getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
const PostDominatorTree *PDT =
&getAnalysis<PostDominatorTreeWrapperPass>(F).getPostDomTree();
for (auto &BB : F) {
if (shouldInstrumentBlock(F, &BB, DT, PDT))
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 (isa<ICmpInst>(&Inst))
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);
}
}
InjectCoverage(F, BlocksToInstrument);
InjectCoverageForIndirectCalls(F, IndirCalls);
InjectTraceForCmp(F, CmpTraceTargets);
InjectTraceForSwitch(F, SwitchTraceTargets);
InjectTraceForDiv(F, DivTraceTargets);
InjectTraceForGep(F, GepTraceTargets);
return true;
}
void SanitizerCoverageModule::CreateFunctionGuardArray(size_t NumGuards,
Function &F) {
if (!Options.TracePCGuard) return;
HasSancovGuardsSection = true;
ArrayType *ArrayOfInt32Ty = ArrayType::get(Int32Ty, NumGuards);
FunctionGuardArray = new GlobalVariable(
*CurModule, ArrayOfInt32Ty, false, GlobalVariable::PrivateLinkage,
Constant::getNullValue(ArrayOfInt32Ty), "__sancov_gen_");
if (auto Comdat = F.getComdat())
FunctionGuardArray->setComdat(Comdat);
FunctionGuardArray->setSection(SanCovTracePCGuardSection);
}
bool SanitizerCoverageModule::InjectCoverage(Function &F,
ArrayRef<BasicBlock *> AllBlocks) {
if (AllBlocks.empty()) return false;
switch (Options.CoverageType) {
case SanitizerCoverageOptions::SCK_None:
return false;
case SanitizerCoverageOptions::SCK_Function:
CreateFunctionGuardArray(1, F);
InjectCoverageAtBlock(F, F.getEntryBlock(), 0, false);
return true;
default: {
bool UseCalls = ClCoverageBlockThreshold < AllBlocks.size();
CreateFunctionGuardArray(AllBlocks.size(), F);
for (size_t i = 0, N = AllBlocks.size(); i < N; i++)
InjectCoverageAtBlock(F, *AllBlocks[i], i, UseCalls);
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 SanitizerCoverageModule::InjectCoverageForIndirectCalls(
Function &F, ArrayRef<Instruction *> IndirCalls) {
if (IndirCalls.empty())
return;
const int CacheSize = 16;
const int CacheAlignment = 64; // Align for better performance.
Type *Ty = ArrayType::get(IntptrTy, CacheSize);
for (auto I : IndirCalls) {
IRBuilder<> IRB(I);
CallSite CS(I);
Value *Callee = CS.getCalledValue();
if (isa<InlineAsm>(Callee))
continue;
GlobalVariable *CalleeCache = new GlobalVariable(
*F.getParent(), Ty, false, GlobalValue::PrivateLinkage,
Constant::getNullValue(Ty), "__sancov_gen_callee_cache");
CalleeCache->setAlignment(CacheAlignment);
if (Options.TracePC || Options.TracePCGuard)
IRB.CreateCall(SanCovTracePCIndir,
IRB.CreatePointerCast(Callee, IntptrTy));
else
IRB.CreateCall(SanCovIndirCallFunction,
{IRB.CreatePointerCast(Callee, IntptrTy),
IRB.CreatePointerCast(CalleeCache, IntptrTy)});
}
}
// For every switch statement we insert a call:
// __sanitizer_cov_trace_switch(CondValue,
// {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
void SanitizerCoverageModule::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);
}
std::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 SanitizerCoverageModule::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 SanitizerCoverageModule::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 SanitizerCoverageModule::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 Ty = Type::getIntNTy(*C, TypeSize);
IRB.CreateCall(
SanCovTraceCmpFunction[CallbackIdx],
{IRB.CreateIntCast(A0, Ty, true), IRB.CreateIntCast(A1, Ty, true)});
}
}
}
void SanitizerCoverageModule::SetNoSanitizeMetadata(Instruction *I) {
I->setMetadata(I->getModule()->getMDKindID("nosanitize"),
MDNode::get(*C, None));
}
void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
size_t Idx, bool UseCalls) {
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.
} else if (Options.TracePCGuard) {
auto GuardPtr = IRB.CreateIntToPtr(
IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
ConstantInt::get(IntptrTy, Idx * 4)),
Int32PtrTy);
if (!UseCalls) {
auto GuardLoad = IRB.CreateLoad(GuardPtr);
GuardLoad->setAtomic(AtomicOrdering::Monotonic);
GuardLoad->setAlignment(8);
SetNoSanitizeMetadata(GuardLoad); // Don't instrument with e.g. asan.
auto Cmp = IRB.CreateICmpNE(
GuardLoad, Constant::getNullValue(GuardLoad->getType()));
auto Ins = SplitBlockAndInsertIfThen(
Cmp, &*IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
IRB.SetInsertPoint(Ins);
IRB.SetCurrentDebugLocation(EntryLoc);
}
IRB.CreateCall(SanCovTracePCGuard, GuardPtr);
IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
} else {
Value *GuardP = IRB.CreateAdd(
IRB.CreatePointerCast(GuardArray, IntptrTy),
ConstantInt::get(IntptrTy, (1 + NumberOfInstrumentedBlocks()) * 4));
GuardP = IRB.CreateIntToPtr(GuardP, Int32PtrTy);
if (Options.TraceBB) {
IRB.CreateCall(IsEntryBB ? SanCovTraceEnter : SanCovTraceBB, GuardP);
} else if (UseCalls) {
IRB.CreateCall(SanCovWithCheckFunction, GuardP);
} else {
LoadInst *Load = IRB.CreateLoad(GuardP);
Load->setAtomic(AtomicOrdering::Monotonic);
Load->setAlignment(4);
SetNoSanitizeMetadata(Load);
Value *Cmp =
IRB.CreateICmpSGE(Constant::getNullValue(Load->getType()), Load);
Instruction *Ins = SplitBlockAndInsertIfThen(
Cmp, &*IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
IRB.SetInsertPoint(Ins);
IRB.SetCurrentDebugLocation(EntryLoc);
// __sanitizer_cov gets the PC of the instruction using GET_CALLER_PC.
IRB.CreateCall(SanCovFunction, GuardP);
IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
}
}
if (Options.Use8bitCounters) {
IRB.SetInsertPoint(&*IP);
Value *P = IRB.CreateAdd(
IRB.CreatePointerCast(EightBitCounterArray, IntptrTy),
ConstantInt::get(IntptrTy, NumberOfInstrumentedBlocks() - 1));
P = IRB.CreateIntToPtr(P, IRB.getInt8PtrTy());
LoadInst *LI = IRB.CreateLoad(P);
Value *Inc = IRB.CreateAdd(LI, ConstantInt::get(IRB.getInt8Ty(), 1));
StoreInst *SI = IRB.CreateStore(Inc, P);
SetNoSanitizeMetadata(LI);
SetNoSanitizeMetadata(SI);
}
}
char SanitizerCoverageModule::ID = 0;
INITIALIZE_PASS_BEGIN(SanitizerCoverageModule, "sancov",
"SanitizerCoverage: TODO."
"ModulePass",
false, false)
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
INITIALIZE_PASS_END(SanitizerCoverageModule, "sancov",
"SanitizerCoverage: TODO."
"ModulePass",
false, false)
ModulePass *llvm::createSanitizerCoverageModulePass(
const SanitizerCoverageOptions &Options) {
return new SanitizerCoverageModule(Options);
}
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