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llvm-mirror/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
Fangrui Song b451f3588d [sanitizer] Place module_ctor/module_dtor in llvm.used 
This removes an abuse of ELF linker behaviors while keeping Mach-O/COFF linker
behaviors unchanged.

ELF: when module_ctor is in a comdat, this patch removes reliance on a linker
abuse (an SHT_INIT_ARRAY in a section group retains the whole group) by using
SHF_GNU_RETAIN. No linker behavior difference when module_ctor is not in a comdat.

Mach-O: module_ctor gets `N_NO_DEAD_STRIP`. No linker behavior difference
because module_ctor is already referenced by a `S_MOD_INIT_FUNC_POINTERS`
section (GC root).

PE/COFF: no-op. SanitizerCoverage already appends module_ctor to `llvm.used`.
Other sanitizers: llvm.used for local linkage is not implemented in
`TargetLoweringObjectFileCOFF::emitLinkerDirectives` (once implemented or
switched to a non-local linkage, COFF can use module_ctor in comdat (i.e.
generalize ELF-specific rL301586)).

There is no object file size difference.

Reviewed By: vitalybuka

Differential Revision: https://reviews.llvm.org/D106246
2021-07-21 14:03:26 -07:00

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//===-- 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/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/InitializePasses.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/SpecialCaseList.h"
#include "llvm/Support/VirtualFileSystem.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"
const char SanCovTracePCIndirName[] = "__sanitizer_cov_trace_pc_indir";
const char SanCovTracePCName[] = "__sanitizer_cov_trace_pc";
const char SanCovTraceCmp1[] = "__sanitizer_cov_trace_cmp1";
const char SanCovTraceCmp2[] = "__sanitizer_cov_trace_cmp2";
const char SanCovTraceCmp4[] = "__sanitizer_cov_trace_cmp4";
const char SanCovTraceCmp8[] = "__sanitizer_cov_trace_cmp8";
const char SanCovTraceConstCmp1[] = "__sanitizer_cov_trace_const_cmp1";
const char SanCovTraceConstCmp2[] = "__sanitizer_cov_trace_const_cmp2";
const char SanCovTraceConstCmp4[] = "__sanitizer_cov_trace_const_cmp4";
const char SanCovTraceConstCmp8[] = "__sanitizer_cov_trace_const_cmp8";
const char SanCovTraceDiv4[] = "__sanitizer_cov_trace_div4";
const char SanCovTraceDiv8[] = "__sanitizer_cov_trace_div8";
const char SanCovTraceGep[] = "__sanitizer_cov_trace_gep";
const char SanCovTraceSwitchName[] = "__sanitizer_cov_trace_switch";
const char SanCovModuleCtorTracePcGuardName[] =
"sancov.module_ctor_trace_pc_guard";
const char SanCovModuleCtor8bitCountersName[] =
"sancov.module_ctor_8bit_counters";
const char SanCovModuleCtorBoolFlagName[] = "sancov.module_ctor_bool_flag";
static const uint64_t SanCtorAndDtorPriority = 2;
const char SanCovTracePCGuardName[] = "__sanitizer_cov_trace_pc_guard";
const char SanCovTracePCGuardInitName[] = "__sanitizer_cov_trace_pc_guard_init";
const char SanCov8bitCountersInitName[] = "__sanitizer_cov_8bit_counters_init";
const char SanCovBoolFlagInitName[] = "__sanitizer_cov_bool_flag_init";
const char SanCovPCsInitName[] = "__sanitizer_cov_pcs_init";
const char SanCovGuardsSectionName[] = "sancov_guards";
const char SanCovCountersSectionName[] = "sancov_cntrs";
const char SanCovBoolFlagSectionName[] = "sancov_bools";
const char SanCovPCsSectionName[] = "sancov_pcs";
const char 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, inline-8bit-counters, and
// inline-bool-flag.
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>
ClInlineBoolFlag("sanitizer-coverage-inline-bool-flag",
cl::desc("sets a boolean flag 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.InlineBoolFlag |= ClInlineBoolFlag;
Options.PCTable |= ClCreatePCTable;
Options.NoPrune |= !ClPruneBlocks;
Options.StackDepth |= ClStackDepth;
if (!Options.TracePCGuard && !Options.TracePC &&
!Options.Inline8bitCounters && !Options.StackDepth &&
!Options.InlineBoolFlag)
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(),
const SpecialCaseList *Allowlist = nullptr,
const SpecialCaseList *Blocklist = nullptr)
: Options(OverrideFromCL(Options)), Allowlist(Allowlist),
Blocklist(Blocklist) {}
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;
Type *IntptrTy, *IntptrPtrTy, *Int64Ty, *Int64PtrTy, *Int32Ty, *Int32PtrTy,
*Int16Ty, *Int8Ty, *Int8PtrTy, *Int1Ty, *Int1PtrTy;
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 *FunctionBoolArray; // for inline-bool-flag.
GlobalVariable *FunctionPCsArray; // for pc-table.
SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed;
SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed;
SanitizerCoverageOptions Options;
const SpecialCaseList *Allowlist;
const SpecialCaseList *Blocklist;
};
class ModuleSanitizerCoverageLegacyPass : public ModulePass {
public:
ModuleSanitizerCoverageLegacyPass(
const SanitizerCoverageOptions &Options = SanitizerCoverageOptions(),
const std::vector<std::string> &AllowlistFiles =
std::vector<std::string>(),
const std::vector<std::string> &BlocklistFiles =
std::vector<std::string>())
: ModulePass(ID), Options(Options) {
if (AllowlistFiles.size() > 0)
Allowlist = SpecialCaseList::createOrDie(AllowlistFiles,
*vfs::getRealFileSystem());
if (BlocklistFiles.size() > 0)
Blocklist = SpecialCaseList::createOrDie(BlocklistFiles,
*vfs::getRealFileSystem());
initializeModuleSanitizerCoverageLegacyPassPass(
*PassRegistry::getPassRegistry());
}
bool runOnModule(Module &M) override {
ModuleSanitizerCoverage ModuleSancov(Options, Allowlist.get(),
Blocklist.get());
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;
std::unique_ptr<SpecialCaseList> Allowlist;
std::unique_ptr<SpecialCaseList> Blocklist;
};
} // namespace
PreservedAnalyses ModuleSanitizerCoveragePass::run(Module &M,
ModuleAnalysisManager &MAM) {
ModuleSanitizerCoverage ModuleSancov(Options, Allowlist.get(),
Blocklist.get());
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) {
// Use ExternalWeak so that if all sections are discarded due to section
// garbage collection, the linker will not report undefined symbol errors.
// Windows defines the start/stop symbols in compiler-rt so no need for
// ExternalWeak.
GlobalValue::LinkageTypes Linkage = TargetTriple.isOSBinFormatCOFF()
? GlobalVariable::ExternalLinkage
: GlobalVariable::ExternalWeakLinkage;
GlobalVariable *SecStart =
new GlobalVariable(M, Ty, false, Linkage, nullptr,
getSectionStart(Section));
SecStart->setVisibility(GlobalValue::HiddenVisibility);
GlobalVariable *SecEnd =
new GlobalVariable(M, Ty, false, Linkage, nullptr,
getSectionEnd(Section));
SecEnd->setVisibility(GlobalValue::HiddenVisibility);
IRBuilder<> IRB(M.getContext());
if (!TargetTriple.isOSBinFormatCOFF())
return std::make_pair(SecStart, SecEnd);
// 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, PointerType::getUnqual(Ty)),
SecEnd);
}
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;
Type *PtrTy = PointerType::getUnqual(Ty);
std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
M, CtorName, InitFunctionName, {PtrTy, PtrTy}, {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);
}
return CtorFunc;
}
bool ModuleSanitizerCoverage::instrumentModule(
Module &M, DomTreeCallback DTCallback, PostDomTreeCallback PDTCallback) {
if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
return false;
if (Allowlist &&
!Allowlist->inSection("coverage", "src", M.getSourceFileName()))
return false;
if (Blocklist &&
Blocklist->inSection("coverage", "src", M.getSourceFileName()))
return false;
C = &(M.getContext());
DL = &M.getDataLayout();
CurModule = &M;
CurModuleUniqueId = getUniqueModuleId(CurModule);
TargetTriple = Triple(M.getTargetTriple());
FunctionGuardArray = nullptr;
Function8bitCounterArray = nullptr;
FunctionBoolArray = 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());
Int1PtrTy = PointerType::getUnqual(IRB.getInt1Ty());
Int64Ty = IRB.getInt64Ty();
Int32Ty = IRB.getInt32Ty();
Int16Ty = IRB.getInt16Ty();
Int8Ty = IRB.getInt8Ty();
Int1Ty = IRB.getInt1Ty();
SanCovTracePCIndir =
M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy);
// Make sure smaller parameters are zero-extended to i64 if required by the
// target ABI.
AttributeList SanCovTraceCmpZeroExtAL;
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;
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 || SanCovLowestStack->getValueType() != IntptrTy) {
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));
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, Int32Ty,
SanCovGuardsSectionName);
if (Function8bitCounterArray)
Ctor = CreateInitCallsForSections(M, SanCovModuleCtor8bitCountersName,
SanCov8bitCountersInitName, Int8Ty,
SanCovCountersSectionName);
if (FunctionBoolArray) {
Ctor = CreateInitCallsForSections(M, SanCovModuleCtorBoolFlagName,
SanCovBoolFlagInitName, Int1Ty,
SanCovBoolFlagSectionName);
}
if (Ctor && Options.PCTable) {
auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrTy);
FunctionCallee InitFunction = declareSanitizerInitFunction(
M, SanCovPCsInitName, {IntptrPtrTy, IntptrPtrTy});
IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator());
IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second});
}
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_empty(BB))
return false;
return llvm::all_of(successors(BB), [&](const BasicBlock *SUCC) {
return DT->dominates(BB, SUCC);
});
}
// True if block has predecessors and it postdominates all of them.
static bool isFullPostDominator(const BasicBlock *BB,
const PostDominatorTree *PDT) {
if (pred_empty(BB))
return false;
return llvm::all_of(predecessors(BB), [&](const BasicBlock *PRED) {
return PDT->dominates(BB, PRED);
});
}
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 (Allowlist && !Allowlist->inSection("coverage", "fun", F.getName()))
return;
if (Blocklist && Blocklist->inSection("coverage", "fun", F.getName()))
return;
if (F.hasFnAttribute(Attribute::NoSanitizeCoverage))
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) {
CallBase *CB = dyn_cast<CallBase>(&Inst);
if (CB && !CB->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() &&
(TargetTriple.isOSBinFormatELF() || !F.isInterposable()))
if (auto Comdat = getOrCreateFunctionComdat(F, TargetTriple))
Array->setComdat(Comdat);
Array->setSection(getSectionName(Section));
Array->setAlignment(Align(DL->getTypeStoreSize(Ty).getFixedSize()));
// sancov_pcs parallels the other metadata section(s). Optimizers (e.g.
// GlobalOpt/ConstantMerge) may not discard sancov_pcs and the other
// section(s) as a unit, so we conservatively retain all unconditionally in
// the compiler.
//
// With comdat (COFF/ELF), the linker can guarantee the associated sections
// will be retained or discarded as a unit, so llvm.compiler.used is
// sufficient. Otherwise, conservatively make all of them retained by the
// linker.
if (Array->hasComdat())
GlobalsToAppendToCompilerUsed.push_back(Array);
else
GlobalsToAppendToUsed.push_back(Array);
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.InlineBoolFlag)
FunctionBoolArray = CreateFunctionLocalArrayInSection(
AllBlocks.size(), F, Int1Ty, SanCovBoolFlagSectionName);
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 || Options.InlineBoolFlag);
for (auto I : IndirCalls) {
IRBuilder<> IRB(I);
CallBase &CB = cast<CallBase>(*I);
Value *Callee = CB.getCalledOperand();
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(drop_begin(Initializers, 2),
[](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 (Use &Idx : GEP->indices())
if (!isa<ConstantInt>(Idx) && Idx->getType()->isIntegerTy())
IRB.CreateCall(SanCovTraceGepFunction,
{IRB.CreateIntCast(Idx, 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 = DILocation::get(SP->getContext(), 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();
if (!EntryLoc)
if (auto *SP = F.getSubprogram())
EntryLoc = DILocation::get(SP->getContext(), 0, 0, SP);
}
IRBuilder<> IRB(&*IP);
IRB.SetCurrentDebugLocation(EntryLoc);
if (Options.TracePC) {
IRB.CreateCall(SanCovTracePC)
->setCannotMerge(); // gets the PC using GET_CALLER_PC.
}
if (Options.TracePCGuard) {
auto GuardPtr = IRB.CreateIntToPtr(
IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
ConstantInt::get(IntptrTy, Idx * 4)),
Int32PtrTy);
IRB.CreateCall(SanCovTracePCGuard, GuardPtr)->setCannotMerge();
}
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.InlineBoolFlag) {
auto FlagPtr = IRB.CreateGEP(
FunctionBoolArray->getValueType(), FunctionBoolArray,
{ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
auto Load = IRB.CreateLoad(Int1Ty, FlagPtr);
auto ThenTerm =
SplitBlockAndInsertIfThen(IRB.CreateIsNull(Load), &*IP, false);
IRBuilder<> ThenIRB(ThenTerm);
auto Store = ThenIRB.CreateStore(ConstantInt::getTrue(Int1Ty), FlagPtr);
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$CM";
if (Section == SanCovBoolFlagSectionName)
return ".SCOV$BM";
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,
const std::vector<std::string> &AllowlistFiles,
const std::vector<std::string> &BlocklistFiles) {
return new ModuleSanitizerCoverageLegacyPass(Options, AllowlistFiles,
BlocklistFiles);
}
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