maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity
llvm-project/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp

515 lines
20 KiB
C++
Raw Blame History

//===-- 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/Transforms/Instrumentation.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Analysis/LibCallSemantics.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DebugInfo.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/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 kSanCovModuleInitName = "__sanitizer_cov_module_init";
static const char *const kSanCovName = "__sanitizer_cov";
static const char *const kSanCovWithCheckName = "__sanitizer_cov_with_check";
static const char *const kSanCovIndirCallName = "__sanitizer_cov_indir_call16";
static const char *const kSanCovTraceEnter = "__sanitizer_cov_trace_func_enter";
static const char *const kSanCovTraceBB = "__sanitizer_cov_trace_basic_block";
static const char *const kSanCovTraceCmp = "__sanitizer_cov_trace_cmp";
static const char *const kSanCovTraceSwitch = "__sanitizer_cov_trace_switch";
static const char *const kSanCovModuleCtorName = "sancov.module_ctor";
static const uint64_t kSanCtorAndDtorPriority = 2;
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(500));
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>
ClExperimentalCMPTracing("sanitizer-coverage-experimental-trace-compares",
cl::desc("Experimental tracing of CMP and similar "
"instructions"),
cl::Hidden, cl::init(false));
// 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 |= ClExperimentalCMPTracing;
Options.Use8bitCounters |= ClUse8bitCounters;
return Options;
}
class SanitizerCoverageModule : public ModulePass {
public:
SanitizerCoverageModule(
const SanitizerCoverageOptions &Options = SanitizerCoverageOptions())
: ModulePass(ID), Options(OverrideFromCL(Options)) {}
bool runOnModule(Module &M) override;
bool runOnFunction(Function &F);
static char ID; // Pass identification, replacement for typeid
const char *getPassName() const override {
return "SanitizerCoverageModule";
}
private:
void InjectCoverageForIndirectCalls(Function &F,
ArrayRef<Instruction *> IndirCalls);
void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
void InjectTraceForSwitch(Function &F,
ArrayRef<Instruction *> SwitchTraceTargets);
bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks);
void SetNoSanitizeMetadata(Instruction *I);
void InjectCoverageAtBlock(Function &F, BasicBlock &BB, bool UseCalls);
unsigned NumberOfInstrumentedBlocks() {
return SanCovFunction->getNumUses() + SanCovWithCheckFunction->getNumUses();
}
Function *SanCovFunction;
Function *SanCovWithCheckFunction;
Function *SanCovIndirCallFunction;
Function *SanCovTraceEnter, *SanCovTraceBB;
Function *SanCovTraceCmpFunction;
Function *SanCovTraceSwitchFunction;
InlineAsm *EmptyAsm;
Type *IntptrTy, *Int64Ty, *Int64PtrTy;
Module *CurModule;
LLVMContext *C;
const DataLayout *DL;
GlobalVariable *GuardArray;
GlobalVariable *EightBitCounterArray;
SanitizerCoverageOptions Options;
};
} // namespace
bool SanitizerCoverageModule::runOnModule(Module &M) {
if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
return false;
C = &(M.getContext());
DL = &M.getDataLayout();
CurModule = &M;
IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
Type *VoidTy = Type::getVoidTy(*C);
IRBuilder<> IRB(*C);
Type *Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
Type *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty());
Int64Ty = IRB.getInt64Ty();
SanCovFunction = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(kSanCovName, VoidTy, Int32PtrTy, nullptr));
SanCovWithCheckFunction = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(kSanCovWithCheckName, VoidTy, Int32PtrTy, nullptr));
SanCovIndirCallFunction =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
kSanCovIndirCallName, VoidTy, IntptrTy, IntptrTy, nullptr));
SanCovTraceCmpFunction =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
kSanCovTraceCmp, VoidTy, Int64Ty, Int64Ty, Int64Ty, nullptr));
SanCovTraceSwitchFunction =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
kSanCovTraceSwitch, 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);
if (Options.TraceBB) {
SanCovTraceEnter = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(kSanCovTraceEnter, VoidTy, Int32PtrTy, nullptr));
SanCovTraceBB = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(kSanCovTraceBB, 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();
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();
// 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);
GlobalVariable *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 kCounterAlignment = 16;
Type *Int8ArrayNTy =
ArrayType::get(Int8Ty, RoundUpToAlignment(N, kCounterAlignment));
RealEightBitCounterArray = new GlobalVariable(
M, Int8ArrayNTy, false, GlobalValue::PrivateLinkage,
Constant::getNullValue(Int8ArrayNTy), "__sancov_gen_cov_counter");
RealEightBitCounterArray->setAlignment(kCounterAlignment);
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);
Function *CtorFunc;
std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
M, kSanCovModuleCtorName, kSanCovModuleInitName,
{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, kSanCtorAndDtorPriority);
return true;
}
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.
// 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> AllBlocks;
SmallVector<Instruction*, 8> CmpTraceTargets;
SmallVector<Instruction*, 8> SwitchTraceTargets;
for (auto &BB : F) {
AllBlocks.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);
}
}
}
InjectCoverage(F, AllBlocks);
InjectCoverageForIndirectCalls(F, IndirCalls);
InjectTraceForCmp(F, CmpTraceTargets);
InjectTraceForSwitch(F, SwitchTraceTargets);
return true;
}
bool SanitizerCoverageModule::InjectCoverage(Function &F,
ArrayRef<BasicBlock *> AllBlocks) {
switch (Options.CoverageType) {
case SanitizerCoverageOptions::SCK_None:
return false;
case SanitizerCoverageOptions::SCK_Function:
InjectCoverageAtBlock(F, F.getEntryBlock(), false);
return true;
default: {
bool UseCalls = ClCoverageBlockThreshold < AllBlocks.size();
for (auto BB : AllBlocks)
InjectCoverageAtBlock(F, *BB, 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 kCacheSize 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.
// kCacheSize is encoded in the name of the run-time function.
void SanitizerCoverageModule::InjectCoverageForIndirectCalls(
Function &F, ArrayRef<Instruction *> IndirCalls) {
if (IndirCalls.empty()) return;
const int kCacheSize = 16;
const int kCacheAlignment = 64; // Align for better performance.
Type *Ty = ArrayType::get(IntptrTy, kCacheSize);
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(kCacheAlignment);
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 &F, 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);
}
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::InjectTraceForCmp(
Function &F, 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());
// __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
IRB.CreateCall(
SanCovTraceCmpFunction,
{ConstantInt::get(Int64Ty, (TypeSize << 32) | ICMP->getPredicate()),
IRB.CreateIntCast(A0, Int64Ty, true),
IRB.CreateIntCast(A1, Int64Ty, true)});
}
}
}
void SanitizerCoverageModule::SetNoSanitizeMetadata(Instruction *I) {
I->setMetadata(
I->getParent()->getParent()->getParent()->getMDKindID("nosanitize"),
MDNode::get(*C, None));
}
void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
bool UseCalls) {
// 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;
BasicBlock::iterator IP = BB.getFirstInsertionPt();
bool IsEntryBB = &BB == &F.getEntryBlock();
DebugLoc EntryLoc;
if (IsEntryBB) {
if (auto SP = getDISubprogram(&F))
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);
Value *GuardP = IRB.CreateAdd(
IRB.CreatePointerCast(GuardArray, IntptrTy),
ConstantInt::get(IntptrTy, (1 + NumberOfInstrumentedBlocks()) * 4));
Type *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
GuardP = IRB.CreateIntToPtr(GuardP, Int32PtrTy);
if (UseCalls) {
IRB.CreateCall(SanCovWithCheckFunction, GuardP);
} else {
LoadInst *Load = IRB.CreateLoad(GuardP);
Load->setAtomic(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);
}
if (Options.TraceBB) {
// Experimental support for tracing.
// Insert a callback with the same guard variable as used for coverage.
IRB.SetInsertPoint(IP);
IRB.CreateCall(IsEntryBB ? SanCovTraceEnter : SanCovTraceBB, GuardP);
}
}
char SanitizerCoverageModule::ID = 0;
INITIALIZE_PASS(SanitizerCoverageModule, "sancov",
"SanitizerCoverage: TODO."
"ModulePass", false, false)
ModulePass *llvm::createSanitizerCoverageModulePass(
const SanitizerCoverageOptions &Options) {
return new SanitizerCoverageModule(Options);
}
Reference in New Issue View Git Blame Copy Permalink