1 //===-- SanitizerCoverage.cpp - coverage instrumentation for sanitizers ---===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // Coverage instrumentation done on LLVM IR level, works with Sanitizers. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "llvm/Transforms/Instrumentation/SanitizerCoverage.h" 14 #include "llvm/ADT/ArrayRef.h" 15 #include "llvm/ADT/SmallVector.h" 16 #include "llvm/Analysis/EHPersonalities.h" 17 #include "llvm/Analysis/PostDominators.h" 18 #include "llvm/IR/CFG.h" 19 #include "llvm/IR/CallSite.h" 20 #include "llvm/IR/Constant.h" 21 #include "llvm/IR/DataLayout.h" 22 #include "llvm/IR/DebugInfo.h" 23 #include "llvm/IR/Dominators.h" 24 #include "llvm/IR/Function.h" 25 #include "llvm/IR/GlobalVariable.h" 26 #include "llvm/IR/IRBuilder.h" 27 #include "llvm/IR/InlineAsm.h" 28 #include "llvm/IR/IntrinsicInst.h" 29 #include "llvm/IR/Intrinsics.h" 30 #include "llvm/IR/LLVMContext.h" 31 #include "llvm/IR/MDBuilder.h" 32 #include "llvm/IR/Mangler.h" 33 #include "llvm/IR/Module.h" 34 #include "llvm/IR/Type.h" 35 #include "llvm/Support/CommandLine.h" 36 #include "llvm/Support/Debug.h" 37 #include "llvm/Support/raw_ostream.h" 38 #include "llvm/Transforms/Instrumentation.h" 39 #include "llvm/Transforms/Utils/BasicBlockUtils.h" 40 #include "llvm/Transforms/Utils/ModuleUtils.h" 41 42 using namespace llvm; 43 44 #define DEBUG_TYPE "sancov" 45 46 static const char *const SanCovTracePCIndirName = 47 "__sanitizer_cov_trace_pc_indir"; 48 static const char *const SanCovTracePCName = "__sanitizer_cov_trace_pc"; 49 static const char *const SanCovTraceCmp1 = "__sanitizer_cov_trace_cmp1"; 50 static const char *const SanCovTraceCmp2 = "__sanitizer_cov_trace_cmp2"; 51 static const char *const SanCovTraceCmp4 = "__sanitizer_cov_trace_cmp4"; 52 static const char *const SanCovTraceCmp8 = "__sanitizer_cov_trace_cmp8"; 53 static const char *const SanCovTraceConstCmp1 = 54 "__sanitizer_cov_trace_const_cmp1"; 55 static const char *const SanCovTraceConstCmp2 = 56 "__sanitizer_cov_trace_const_cmp2"; 57 static const char *const SanCovTraceConstCmp4 = 58 "__sanitizer_cov_trace_const_cmp4"; 59 static const char *const SanCovTraceConstCmp8 = 60 "__sanitizer_cov_trace_const_cmp8"; 61 static const char *const SanCovTraceDiv4 = "__sanitizer_cov_trace_div4"; 62 static const char *const SanCovTraceDiv8 = "__sanitizer_cov_trace_div8"; 63 static const char *const SanCovTraceGep = "__sanitizer_cov_trace_gep"; 64 static const char *const SanCovTraceSwitchName = "__sanitizer_cov_trace_switch"; 65 static const char *const SanCovModuleCtorTracePcGuardName = 66 "sancov.module_ctor_trace_pc_guard"; 67 static const char *const SanCovModuleCtor8bitCountersName = 68 "sancov.module_ctor_8bit_counters"; 69 static const uint64_t SanCtorAndDtorPriority = 2; 70 71 static const char *const SanCovTracePCGuardName = 72 "__sanitizer_cov_trace_pc_guard"; 73 static const char *const SanCovTracePCGuardInitName = 74 "__sanitizer_cov_trace_pc_guard_init"; 75 static const char *const SanCov8bitCountersInitName = 76 "__sanitizer_cov_8bit_counters_init"; 77 static const char *const SanCovPCsInitName = "__sanitizer_cov_pcs_init"; 78 79 static const char *const SanCovGuardsSectionName = "sancov_guards"; 80 static const char *const SanCovCountersSectionName = "sancov_cntrs"; 81 static const char *const SanCovPCsSectionName = "sancov_pcs"; 82 83 static const char *const SanCovLowestStackName = "__sancov_lowest_stack"; 84 85 static cl::opt<int> ClCoverageLevel( 86 "sanitizer-coverage-level", 87 cl::desc("Sanitizer Coverage. 0: none, 1: entry block, 2: all blocks, " 88 "3: all blocks and critical edges"), 89 cl::Hidden, cl::init(0)); 90 91 static cl::opt<bool> ClTracePC("sanitizer-coverage-trace-pc", 92 cl::desc("Experimental pc tracing"), cl::Hidden, 93 cl::init(false)); 94 95 static cl::opt<bool> ClTracePCGuard("sanitizer-coverage-trace-pc-guard", 96 cl::desc("pc tracing with a guard"), 97 cl::Hidden, cl::init(false)); 98 99 // If true, we create a global variable that contains PCs of all instrumented 100 // BBs, put this global into a named section, and pass this section's bounds 101 // to __sanitizer_cov_pcs_init. 102 // This way the coverage instrumentation does not need to acquire the PCs 103 // at run-time. Works with trace-pc-guard and inline-8bit-counters. 104 static cl::opt<bool> ClCreatePCTable("sanitizer-coverage-pc-table", 105 cl::desc("create a static PC table"), 106 cl::Hidden, cl::init(false)); 107 108 static cl::opt<bool> 109 ClInline8bitCounters("sanitizer-coverage-inline-8bit-counters", 110 cl::desc("increments 8-bit counter for every edge"), 111 cl::Hidden, cl::init(false)); 112 113 static cl::opt<bool> 114 ClCMPTracing("sanitizer-coverage-trace-compares", 115 cl::desc("Tracing of CMP and similar instructions"), 116 cl::Hidden, cl::init(false)); 117 118 static cl::opt<bool> ClDIVTracing("sanitizer-coverage-trace-divs", 119 cl::desc("Tracing of DIV instructions"), 120 cl::Hidden, cl::init(false)); 121 122 static cl::opt<bool> ClGEPTracing("sanitizer-coverage-trace-geps", 123 cl::desc("Tracing of GEP instructions"), 124 cl::Hidden, cl::init(false)); 125 126 static cl::opt<bool> 127 ClPruneBlocks("sanitizer-coverage-prune-blocks", 128 cl::desc("Reduce the number of instrumented blocks"), 129 cl::Hidden, cl::init(true)); 130 131 static cl::opt<bool> ClStackDepth("sanitizer-coverage-stack-depth", 132 cl::desc("max stack depth tracing"), 133 cl::Hidden, cl::init(false)); 134 135 namespace { 136 137 SanitizerCoverageOptions getOptions(int LegacyCoverageLevel) { 138 SanitizerCoverageOptions Res; 139 switch (LegacyCoverageLevel) { 140 case 0: 141 Res.CoverageType = SanitizerCoverageOptions::SCK_None; 142 break; 143 case 1: 144 Res.CoverageType = SanitizerCoverageOptions::SCK_Function; 145 break; 146 case 2: 147 Res.CoverageType = SanitizerCoverageOptions::SCK_BB; 148 break; 149 case 3: 150 Res.CoverageType = SanitizerCoverageOptions::SCK_Edge; 151 break; 152 case 4: 153 Res.CoverageType = SanitizerCoverageOptions::SCK_Edge; 154 Res.IndirectCalls = true; 155 break; 156 } 157 return Res; 158 } 159 160 SanitizerCoverageOptions OverrideFromCL(SanitizerCoverageOptions Options) { 161 // Sets CoverageType and IndirectCalls. 162 SanitizerCoverageOptions CLOpts = getOptions(ClCoverageLevel); 163 Options.CoverageType = std::max(Options.CoverageType, CLOpts.CoverageType); 164 Options.IndirectCalls |= CLOpts.IndirectCalls; 165 Options.TraceCmp |= ClCMPTracing; 166 Options.TraceDiv |= ClDIVTracing; 167 Options.TraceGep |= ClGEPTracing; 168 Options.TracePC |= ClTracePC; 169 Options.TracePCGuard |= ClTracePCGuard; 170 Options.Inline8bitCounters |= ClInline8bitCounters; 171 Options.PCTable |= ClCreatePCTable; 172 Options.NoPrune |= !ClPruneBlocks; 173 Options.StackDepth |= ClStackDepth; 174 if (!Options.TracePCGuard && !Options.TracePC && 175 !Options.Inline8bitCounters && !Options.StackDepth) 176 Options.TracePCGuard = true; // TracePCGuard is default. 177 return Options; 178 } 179 180 using DomTreeCallback = function_ref<const DominatorTree *(Function &F)>; 181 using PostDomTreeCallback = 182 function_ref<const PostDominatorTree *(Function &F)>; 183 184 class ModuleSanitizerCoverage { 185 public: 186 ModuleSanitizerCoverage( 187 const SanitizerCoverageOptions &Options = SanitizerCoverageOptions()) 188 : Options(OverrideFromCL(Options)) {} 189 bool instrumentModule(Module &M, DomTreeCallback DTCallback, 190 PostDomTreeCallback PDTCallback); 191 192 private: 193 void instrumentFunction(Function &F, DomTreeCallback DTCallback, 194 PostDomTreeCallback PDTCallback); 195 void InjectCoverageForIndirectCalls(Function &F, 196 ArrayRef<Instruction *> IndirCalls); 197 void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets); 198 void InjectTraceForDiv(Function &F, 199 ArrayRef<BinaryOperator *> DivTraceTargets); 200 void InjectTraceForGep(Function &F, 201 ArrayRef<GetElementPtrInst *> GepTraceTargets); 202 void InjectTraceForSwitch(Function &F, 203 ArrayRef<Instruction *> SwitchTraceTargets); 204 bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks, 205 bool IsLeafFunc = true); 206 GlobalVariable *CreateFunctionLocalArrayInSection(size_t NumElements, 207 Function &F, Type *Ty, 208 const char *Section); 209 GlobalVariable *CreatePCArray(Function &F, ArrayRef<BasicBlock *> AllBlocks); 210 void CreateFunctionLocalArrays(Function &F, ArrayRef<BasicBlock *> AllBlocks); 211 void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx, 212 bool IsLeafFunc = true); 213 Function *CreateInitCallsForSections(Module &M, const char *CtorName, 214 const char *InitFunctionName, Type *Ty, 215 const char *Section); 216 std::pair<Value *, Value *> CreateSecStartEnd(Module &M, const char *Section, 217 Type *Ty); 218 219 void SetNoSanitizeMetadata(Instruction *I) { 220 I->setMetadata(I->getModule()->getMDKindID("nosanitize"), 221 MDNode::get(*C, None)); 222 } 223 224 std::string getSectionName(const std::string &Section) const; 225 std::string getSectionStart(const std::string &Section) const; 226 std::string getSectionEnd(const std::string &Section) const; 227 FunctionCallee SanCovTracePCIndir; 228 FunctionCallee SanCovTracePC, SanCovTracePCGuard; 229 FunctionCallee SanCovTraceCmpFunction[4]; 230 FunctionCallee SanCovTraceConstCmpFunction[4]; 231 FunctionCallee SanCovTraceDivFunction[2]; 232 FunctionCallee SanCovTraceGepFunction; 233 FunctionCallee SanCovTraceSwitchFunction; 234 GlobalVariable *SanCovLowestStack; 235 InlineAsm *EmptyAsm; 236 Type *IntptrTy, *IntptrPtrTy, *Int64Ty, *Int64PtrTy, *Int32Ty, *Int32PtrTy, 237 *Int16Ty, *Int8Ty, *Int8PtrTy; 238 Module *CurModule; 239 std::string CurModuleUniqueId; 240 Triple TargetTriple; 241 LLVMContext *C; 242 const DataLayout *DL; 243 244 GlobalVariable *FunctionGuardArray; // for trace-pc-guard. 245 GlobalVariable *Function8bitCounterArray; // for inline-8bit-counters. 246 GlobalVariable *FunctionPCsArray; // for pc-table. 247 SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed; 248 SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed; 249 250 SanitizerCoverageOptions Options; 251 }; 252 253 class ModuleSanitizerCoverageLegacyPass : public ModulePass { 254 public: 255 ModuleSanitizerCoverageLegacyPass( 256 const SanitizerCoverageOptions &Options = SanitizerCoverageOptions()) 257 : ModulePass(ID), Options(Options) { 258 initializeModuleSanitizerCoverageLegacyPassPass( 259 *PassRegistry::getPassRegistry()); 260 } 261 bool runOnModule(Module &M) override { 262 ModuleSanitizerCoverage ModuleSancov(Options); 263 auto DTCallback = [this](Function &F) -> const DominatorTree * { 264 return &this->getAnalysis<DominatorTreeWrapperPass>(F).getDomTree(); 265 }; 266 auto PDTCallback = [this](Function &F) -> const PostDominatorTree * { 267 return &this->getAnalysis<PostDominatorTreeWrapperPass>(F) 268 .getPostDomTree(); 269 }; 270 return ModuleSancov.instrumentModule(M, DTCallback, PDTCallback); 271 } 272 273 static char ID; // Pass identification, replacement for typeid 274 StringRef getPassName() const override { return "ModuleSanitizerCoverage"; } 275 276 void getAnalysisUsage(AnalysisUsage &AU) const override { 277 AU.addRequired<DominatorTreeWrapperPass>(); 278 AU.addRequired<PostDominatorTreeWrapperPass>(); 279 } 280 281 private: 282 SanitizerCoverageOptions Options; 283 }; 284 285 } // namespace 286 287 PreservedAnalyses ModuleSanitizerCoveragePass::run(Module &M, 288 ModuleAnalysisManager &MAM) { 289 ModuleSanitizerCoverage ModuleSancov(Options); 290 auto &FAM = MAM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager(); 291 auto DTCallback = [&FAM](Function &F) -> const DominatorTree * { 292 return &FAM.getResult<DominatorTreeAnalysis>(F); 293 }; 294 auto PDTCallback = [&FAM](Function &F) -> const PostDominatorTree * { 295 return &FAM.getResult<PostDominatorTreeAnalysis>(F); 296 }; 297 if (ModuleSancov.instrumentModule(M, DTCallback, PDTCallback)) 298 return PreservedAnalyses::none(); 299 return PreservedAnalyses::all(); 300 } 301 302 std::pair<Value *, Value *> 303 ModuleSanitizerCoverage::CreateSecStartEnd(Module &M, const char *Section, 304 Type *Ty) { 305 GlobalVariable *SecStart = 306 new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage, nullptr, 307 getSectionStart(Section)); 308 SecStart->setVisibility(GlobalValue::HiddenVisibility); 309 GlobalVariable *SecEnd = 310 new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage, 311 nullptr, getSectionEnd(Section)); 312 SecEnd->setVisibility(GlobalValue::HiddenVisibility); 313 IRBuilder<> IRB(M.getContext()); 314 Value *SecEndPtr = IRB.CreatePointerCast(SecEnd, Ty); 315 if (!TargetTriple.isOSBinFormatCOFF()) 316 return std::make_pair(IRB.CreatePointerCast(SecStart, Ty), SecEndPtr); 317 318 // Account for the fact that on windows-msvc __start_* symbols actually 319 // point to a uint64_t before the start of the array. 320 auto SecStartI8Ptr = IRB.CreatePointerCast(SecStart, Int8PtrTy); 321 auto GEP = IRB.CreateGEP(Int8Ty, SecStartI8Ptr, 322 ConstantInt::get(IntptrTy, sizeof(uint64_t))); 323 return std::make_pair(IRB.CreatePointerCast(GEP, Ty), SecEndPtr); 324 } 325 326 Function *ModuleSanitizerCoverage::CreateInitCallsForSections( 327 Module &M, const char *CtorName, const char *InitFunctionName, Type *Ty, 328 const char *Section) { 329 auto SecStartEnd = CreateSecStartEnd(M, Section, Ty); 330 auto SecStart = SecStartEnd.first; 331 auto SecEnd = SecStartEnd.second; 332 Function *CtorFunc; 333 std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions( 334 M, CtorName, InitFunctionName, {Ty, Ty}, {SecStart, SecEnd}); 335 assert(CtorFunc->getName() == CtorName); 336 337 if (TargetTriple.supportsCOMDAT()) { 338 // Use comdat to dedup CtorFunc. 339 CtorFunc->setComdat(M.getOrInsertComdat(CtorName)); 340 appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc); 341 } else { 342 appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority); 343 } 344 345 if (TargetTriple.isOSBinFormatCOFF()) { 346 // In COFF files, if the contructors are set as COMDAT (they are because 347 // COFF supports COMDAT) and the linker flag /OPT:REF (strip unreferenced 348 // functions and data) is used, the constructors get stripped. To prevent 349 // this, give the constructors weak ODR linkage and ensure the linker knows 350 // to include the sancov constructor. This way the linker can deduplicate 351 // the constructors but always leave one copy. 352 CtorFunc->setLinkage(GlobalValue::WeakODRLinkage); 353 appendToUsed(M, CtorFunc); 354 } 355 return CtorFunc; 356 } 357 358 bool ModuleSanitizerCoverage::instrumentModule( 359 Module &M, DomTreeCallback DTCallback, PostDomTreeCallback PDTCallback) { 360 if (Options.CoverageType == SanitizerCoverageOptions::SCK_None) 361 return false; 362 C = &(M.getContext()); 363 DL = &M.getDataLayout(); 364 CurModule = &M; 365 CurModuleUniqueId = getUniqueModuleId(CurModule); 366 TargetTriple = Triple(M.getTargetTriple()); 367 FunctionGuardArray = nullptr; 368 Function8bitCounterArray = nullptr; 369 FunctionPCsArray = nullptr; 370 IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits()); 371 IntptrPtrTy = PointerType::getUnqual(IntptrTy); 372 Type *VoidTy = Type::getVoidTy(*C); 373 IRBuilder<> IRB(*C); 374 Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty()); 375 Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty()); 376 Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty()); 377 Int64Ty = IRB.getInt64Ty(); 378 Int32Ty = IRB.getInt32Ty(); 379 Int16Ty = IRB.getInt16Ty(); 380 Int8Ty = IRB.getInt8Ty(); 381 382 SanCovTracePCIndir = 383 M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy); 384 // Make sure smaller parameters are zero-extended to i64 as required by the 385 // x86_64 ABI. 386 AttributeList SanCovTraceCmpZeroExtAL; 387 if (TargetTriple.getArch() == Triple::x86_64) { 388 SanCovTraceCmpZeroExtAL = 389 SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 0, Attribute::ZExt); 390 SanCovTraceCmpZeroExtAL = 391 SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 1, Attribute::ZExt); 392 } 393 394 SanCovTraceCmpFunction[0] = 395 M.getOrInsertFunction(SanCovTraceCmp1, SanCovTraceCmpZeroExtAL, VoidTy, 396 IRB.getInt8Ty(), IRB.getInt8Ty()); 397 SanCovTraceCmpFunction[1] = 398 M.getOrInsertFunction(SanCovTraceCmp2, SanCovTraceCmpZeroExtAL, VoidTy, 399 IRB.getInt16Ty(), IRB.getInt16Ty()); 400 SanCovTraceCmpFunction[2] = 401 M.getOrInsertFunction(SanCovTraceCmp4, SanCovTraceCmpZeroExtAL, VoidTy, 402 IRB.getInt32Ty(), IRB.getInt32Ty()); 403 SanCovTraceCmpFunction[3] = 404 M.getOrInsertFunction(SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty); 405 406 SanCovTraceConstCmpFunction[0] = M.getOrInsertFunction( 407 SanCovTraceConstCmp1, SanCovTraceCmpZeroExtAL, VoidTy, Int8Ty, Int8Ty); 408 SanCovTraceConstCmpFunction[1] = M.getOrInsertFunction( 409 SanCovTraceConstCmp2, SanCovTraceCmpZeroExtAL, VoidTy, Int16Ty, Int16Ty); 410 SanCovTraceConstCmpFunction[2] = M.getOrInsertFunction( 411 SanCovTraceConstCmp4, SanCovTraceCmpZeroExtAL, VoidTy, Int32Ty, Int32Ty); 412 SanCovTraceConstCmpFunction[3] = 413 M.getOrInsertFunction(SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty); 414 415 { 416 AttributeList AL; 417 if (TargetTriple.getArch() == Triple::x86_64) 418 AL = AL.addParamAttribute(*C, 0, Attribute::ZExt); 419 SanCovTraceDivFunction[0] = 420 M.getOrInsertFunction(SanCovTraceDiv4, AL, VoidTy, IRB.getInt32Ty()); 421 } 422 SanCovTraceDivFunction[1] = 423 M.getOrInsertFunction(SanCovTraceDiv8, VoidTy, Int64Ty); 424 SanCovTraceGepFunction = 425 M.getOrInsertFunction(SanCovTraceGep, VoidTy, IntptrTy); 426 SanCovTraceSwitchFunction = 427 M.getOrInsertFunction(SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy); 428 429 Constant *SanCovLowestStackConstant = 430 M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy); 431 SanCovLowestStack = dyn_cast<GlobalVariable>(SanCovLowestStackConstant); 432 if (!SanCovLowestStack) { 433 C->emitError(StringRef("'") + SanCovLowestStackName + 434 "' should not be declared by the user"); 435 return true; 436 } 437 SanCovLowestStack->setThreadLocalMode( 438 GlobalValue::ThreadLocalMode::InitialExecTLSModel); 439 if (Options.StackDepth && !SanCovLowestStack->isDeclaration()) 440 SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy)); 441 442 // We insert an empty inline asm after cov callbacks to avoid callback merge. 443 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false), 444 StringRef(""), StringRef(""), 445 /*hasSideEffects=*/true); 446 447 SanCovTracePC = M.getOrInsertFunction(SanCovTracePCName, VoidTy); 448 SanCovTracePCGuard = 449 M.getOrInsertFunction(SanCovTracePCGuardName, VoidTy, Int32PtrTy); 450 451 for (auto &F : M) 452 instrumentFunction(F, DTCallback, PDTCallback); 453 454 Function *Ctor = nullptr; 455 456 if (FunctionGuardArray) 457 Ctor = CreateInitCallsForSections(M, SanCovModuleCtorTracePcGuardName, 458 SanCovTracePCGuardInitName, Int32PtrTy, 459 SanCovGuardsSectionName); 460 if (Function8bitCounterArray) 461 Ctor = CreateInitCallsForSections(M, SanCovModuleCtor8bitCountersName, 462 SanCov8bitCountersInitName, Int8PtrTy, 463 SanCovCountersSectionName); 464 if (Ctor && Options.PCTable) { 465 auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrPtrTy); 466 FunctionCallee InitFunction = declareSanitizerInitFunction( 467 M, SanCovPCsInitName, {IntptrPtrTy, IntptrPtrTy}); 468 IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator()); 469 IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second}); 470 } 471 // We don't reference these arrays directly in any of our runtime functions, 472 // so we need to prevent them from being dead stripped. 473 if (TargetTriple.isOSBinFormatMachO()) 474 appendToUsed(M, GlobalsToAppendToUsed); 475 appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed); 476 return true; 477 } 478 479 // True if block has successors and it dominates all of them. 480 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) { 481 if (succ_begin(BB) == succ_end(BB)) 482 return false; 483 484 for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) { 485 if (!DT->dominates(BB, SUCC)) 486 return false; 487 } 488 489 return true; 490 } 491 492 // True if block has predecessors and it postdominates all of them. 493 static bool isFullPostDominator(const BasicBlock *BB, 494 const PostDominatorTree *PDT) { 495 if (pred_begin(BB) == pred_end(BB)) 496 return false; 497 498 for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) { 499 if (!PDT->dominates(BB, PRED)) 500 return false; 501 } 502 503 return true; 504 } 505 506 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB, 507 const DominatorTree *DT, 508 const PostDominatorTree *PDT, 509 const SanitizerCoverageOptions &Options) { 510 // Don't insert coverage for blocks containing nothing but unreachable: we 511 // will never call __sanitizer_cov() for them, so counting them in 512 // NumberOfInstrumentedBlocks() might complicate calculation of code coverage 513 // percentage. Also, unreachable instructions frequently have no debug 514 // locations. 515 if (isa<UnreachableInst>(BB->getFirstNonPHIOrDbgOrLifetime())) 516 return false; 517 518 // Don't insert coverage into blocks without a valid insertion point 519 // (catchswitch blocks). 520 if (BB->getFirstInsertionPt() == BB->end()) 521 return false; 522 523 if (Options.NoPrune || &F.getEntryBlock() == BB) 524 return true; 525 526 if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function && 527 &F.getEntryBlock() != BB) 528 return false; 529 530 // Do not instrument full dominators, or full post-dominators with multiple 531 // predecessors. 532 return !isFullDominator(BB, DT) 533 && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor()); 534 } 535 536 537 // Returns true iff From->To is a backedge. 538 // A twist here is that we treat From->To as a backedge if 539 // * To dominates From or 540 // * To->UniqueSuccessor dominates From 541 static bool IsBackEdge(BasicBlock *From, BasicBlock *To, 542 const DominatorTree *DT) { 543 if (DT->dominates(To, From)) 544 return true; 545 if (auto Next = To->getUniqueSuccessor()) 546 if (DT->dominates(Next, From)) 547 return true; 548 return false; 549 } 550 551 // Prunes uninteresting Cmp instrumentation: 552 // * CMP instructions that feed into loop backedge branch. 553 // 554 // Note that Cmp pruning is controlled by the same flag as the 555 // BB pruning. 556 static bool IsInterestingCmp(ICmpInst *CMP, const DominatorTree *DT, 557 const SanitizerCoverageOptions &Options) { 558 if (!Options.NoPrune) 559 if (CMP->hasOneUse()) 560 if (auto BR = dyn_cast<BranchInst>(CMP->user_back())) 561 for (BasicBlock *B : BR->successors()) 562 if (IsBackEdge(BR->getParent(), B, DT)) 563 return false; 564 return true; 565 } 566 567 void ModuleSanitizerCoverage::instrumentFunction( 568 Function &F, DomTreeCallback DTCallback, PostDomTreeCallback PDTCallback) { 569 if (F.empty()) 570 return; 571 if (F.getName().find(".module_ctor") != std::string::npos) 572 return; // Should not instrument sanitizer init functions. 573 if (F.getName().startswith("__sanitizer_")) 574 return; // Don't instrument __sanitizer_* callbacks. 575 // Don't touch available_externally functions, their actual body is elewhere. 576 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) 577 return; 578 // Don't instrument MSVC CRT configuration helpers. They may run before normal 579 // initialization. 580 if (F.getName() == "__local_stdio_printf_options" || 581 F.getName() == "__local_stdio_scanf_options") 582 return; 583 if (isa<UnreachableInst>(F.getEntryBlock().getTerminator())) 584 return; 585 // Don't instrument functions using SEH for now. Splitting basic blocks like 586 // we do for coverage breaks WinEHPrepare. 587 // FIXME: Remove this when SEH no longer uses landingpad pattern matching. 588 if (F.hasPersonalityFn() && 589 isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn()))) 590 return; 591 if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge) 592 SplitAllCriticalEdges(F, CriticalEdgeSplittingOptions().setIgnoreUnreachableDests()); 593 SmallVector<Instruction *, 8> IndirCalls; 594 SmallVector<BasicBlock *, 16> BlocksToInstrument; 595 SmallVector<Instruction *, 8> CmpTraceTargets; 596 SmallVector<Instruction *, 8> SwitchTraceTargets; 597 SmallVector<BinaryOperator *, 8> DivTraceTargets; 598 SmallVector<GetElementPtrInst *, 8> GepTraceTargets; 599 600 const DominatorTree *DT = DTCallback(F); 601 const PostDominatorTree *PDT = PDTCallback(F); 602 bool IsLeafFunc = true; 603 604 for (auto &BB : F) { 605 if (shouldInstrumentBlock(F, &BB, DT, PDT, Options)) 606 BlocksToInstrument.push_back(&BB); 607 for (auto &Inst : BB) { 608 if (Options.IndirectCalls) { 609 CallSite CS(&Inst); 610 if (CS && !CS.getCalledFunction()) 611 IndirCalls.push_back(&Inst); 612 } 613 if (Options.TraceCmp) { 614 if (ICmpInst *CMP = dyn_cast<ICmpInst>(&Inst)) 615 if (IsInterestingCmp(CMP, DT, Options)) 616 CmpTraceTargets.push_back(&Inst); 617 if (isa<SwitchInst>(&Inst)) 618 SwitchTraceTargets.push_back(&Inst); 619 } 620 if (Options.TraceDiv) 621 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst)) 622 if (BO->getOpcode() == Instruction::SDiv || 623 BO->getOpcode() == Instruction::UDiv) 624 DivTraceTargets.push_back(BO); 625 if (Options.TraceGep) 626 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst)) 627 GepTraceTargets.push_back(GEP); 628 if (Options.StackDepth) 629 if (isa<InvokeInst>(Inst) || 630 (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst))) 631 IsLeafFunc = false; 632 } 633 } 634 635 InjectCoverage(F, BlocksToInstrument, IsLeafFunc); 636 InjectCoverageForIndirectCalls(F, IndirCalls); 637 InjectTraceForCmp(F, CmpTraceTargets); 638 InjectTraceForSwitch(F, SwitchTraceTargets); 639 InjectTraceForDiv(F, DivTraceTargets); 640 InjectTraceForGep(F, GepTraceTargets); 641 } 642 643 GlobalVariable *ModuleSanitizerCoverage::CreateFunctionLocalArrayInSection( 644 size_t NumElements, Function &F, Type *Ty, const char *Section) { 645 ArrayType *ArrayTy = ArrayType::get(Ty, NumElements); 646 auto Array = new GlobalVariable( 647 *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage, 648 Constant::getNullValue(ArrayTy), "__sancov_gen_"); 649 650 if (TargetTriple.supportsCOMDAT() && !F.isInterposable()) 651 if (auto Comdat = 652 GetOrCreateFunctionComdat(F, TargetTriple, CurModuleUniqueId)) 653 Array->setComdat(Comdat); 654 Array->setSection(getSectionName(Section)); 655 Array->setAlignment(Ty->isPointerTy() ? DL->getPointerSize() 656 : Ty->getPrimitiveSizeInBits() / 8); 657 GlobalsToAppendToUsed.push_back(Array); 658 GlobalsToAppendToCompilerUsed.push_back(Array); 659 MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F)); 660 Array->addMetadata(LLVMContext::MD_associated, *MD); 661 662 return Array; 663 } 664 665 GlobalVariable * 666 ModuleSanitizerCoverage::CreatePCArray(Function &F, 667 ArrayRef<BasicBlock *> AllBlocks) { 668 size_t N = AllBlocks.size(); 669 assert(N); 670 SmallVector<Constant *, 32> PCs; 671 IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt()); 672 for (size_t i = 0; i < N; i++) { 673 if (&F.getEntryBlock() == AllBlocks[i]) { 674 PCs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy)); 675 PCs.push_back((Constant *)IRB.CreateIntToPtr( 676 ConstantInt::get(IntptrTy, 1), IntptrPtrTy)); 677 } else { 678 PCs.push_back((Constant *)IRB.CreatePointerCast( 679 BlockAddress::get(AllBlocks[i]), IntptrPtrTy)); 680 PCs.push_back((Constant *)IRB.CreateIntToPtr( 681 ConstantInt::get(IntptrTy, 0), IntptrPtrTy)); 682 } 683 } 684 auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, IntptrPtrTy, 685 SanCovPCsSectionName); 686 PCArray->setInitializer( 687 ConstantArray::get(ArrayType::get(IntptrPtrTy, N * 2), PCs)); 688 PCArray->setConstant(true); 689 690 return PCArray; 691 } 692 693 void ModuleSanitizerCoverage::CreateFunctionLocalArrays( 694 Function &F, ArrayRef<BasicBlock *> AllBlocks) { 695 if (Options.TracePCGuard) 696 FunctionGuardArray = CreateFunctionLocalArrayInSection( 697 AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName); 698 699 if (Options.Inline8bitCounters) 700 Function8bitCounterArray = CreateFunctionLocalArrayInSection( 701 AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName); 702 703 if (Options.PCTable) 704 FunctionPCsArray = CreatePCArray(F, AllBlocks); 705 } 706 707 bool ModuleSanitizerCoverage::InjectCoverage(Function &F, 708 ArrayRef<BasicBlock *> AllBlocks, 709 bool IsLeafFunc) { 710 if (AllBlocks.empty()) return false; 711 CreateFunctionLocalArrays(F, AllBlocks); 712 for (size_t i = 0, N = AllBlocks.size(); i < N; i++) 713 InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc); 714 return true; 715 } 716 717 // On every indirect call we call a run-time function 718 // __sanitizer_cov_indir_call* with two parameters: 719 // - callee address, 720 // - global cache array that contains CacheSize pointers (zero-initialized). 721 // The cache is used to speed up recording the caller-callee pairs. 722 // The address of the caller is passed implicitly via caller PC. 723 // CacheSize is encoded in the name of the run-time function. 724 void ModuleSanitizerCoverage::InjectCoverageForIndirectCalls( 725 Function &F, ArrayRef<Instruction *> IndirCalls) { 726 if (IndirCalls.empty()) 727 return; 728 assert(Options.TracePC || Options.TracePCGuard || Options.Inline8bitCounters); 729 for (auto I : IndirCalls) { 730 IRBuilder<> IRB(I); 731 CallSite CS(I); 732 Value *Callee = CS.getCalledValue(); 733 if (isa<InlineAsm>(Callee)) 734 continue; 735 IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy)); 736 } 737 } 738 739 // For every switch statement we insert a call: 740 // __sanitizer_cov_trace_switch(CondValue, 741 // {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... }) 742 743 void ModuleSanitizerCoverage::InjectTraceForSwitch( 744 Function &, ArrayRef<Instruction *> SwitchTraceTargets) { 745 for (auto I : SwitchTraceTargets) { 746 if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) { 747 IRBuilder<> IRB(I); 748 SmallVector<Constant *, 16> Initializers; 749 Value *Cond = SI->getCondition(); 750 if (Cond->getType()->getScalarSizeInBits() > 751 Int64Ty->getScalarSizeInBits()) 752 continue; 753 Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases())); 754 Initializers.push_back( 755 ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits())); 756 if (Cond->getType()->getScalarSizeInBits() < 757 Int64Ty->getScalarSizeInBits()) 758 Cond = IRB.CreateIntCast(Cond, Int64Ty, false); 759 for (auto It : SI->cases()) { 760 Constant *C = It.getCaseValue(); 761 if (C->getType()->getScalarSizeInBits() < 762 Int64Ty->getScalarSizeInBits()) 763 C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty); 764 Initializers.push_back(C); 765 } 766 llvm::sort(Initializers.begin() + 2, Initializers.end(), 767 [](const Constant *A, const Constant *B) { 768 return cast<ConstantInt>(A)->getLimitedValue() < 769 cast<ConstantInt>(B)->getLimitedValue(); 770 }); 771 ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size()); 772 GlobalVariable *GV = new GlobalVariable( 773 *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage, 774 ConstantArray::get(ArrayOfInt64Ty, Initializers), 775 "__sancov_gen_cov_switch_values"); 776 IRB.CreateCall(SanCovTraceSwitchFunction, 777 {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)}); 778 } 779 } 780 } 781 782 void ModuleSanitizerCoverage::InjectTraceForDiv( 783 Function &, ArrayRef<BinaryOperator *> DivTraceTargets) { 784 for (auto BO : DivTraceTargets) { 785 IRBuilder<> IRB(BO); 786 Value *A1 = BO->getOperand(1); 787 if (isa<ConstantInt>(A1)) continue; 788 if (!A1->getType()->isIntegerTy()) 789 continue; 790 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType()); 791 int CallbackIdx = TypeSize == 32 ? 0 : 792 TypeSize == 64 ? 1 : -1; 793 if (CallbackIdx < 0) continue; 794 auto Ty = Type::getIntNTy(*C, TypeSize); 795 IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx], 796 {IRB.CreateIntCast(A1, Ty, true)}); 797 } 798 } 799 800 void ModuleSanitizerCoverage::InjectTraceForGep( 801 Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) { 802 for (auto GEP : GepTraceTargets) { 803 IRBuilder<> IRB(GEP); 804 for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I) 805 if (!isa<ConstantInt>(*I) && (*I)->getType()->isIntegerTy()) 806 IRB.CreateCall(SanCovTraceGepFunction, 807 {IRB.CreateIntCast(*I, IntptrTy, true)}); 808 } 809 } 810 811 void ModuleSanitizerCoverage::InjectTraceForCmp( 812 Function &, ArrayRef<Instruction *> CmpTraceTargets) { 813 for (auto I : CmpTraceTargets) { 814 if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) { 815 IRBuilder<> IRB(ICMP); 816 Value *A0 = ICMP->getOperand(0); 817 Value *A1 = ICMP->getOperand(1); 818 if (!A0->getType()->isIntegerTy()) 819 continue; 820 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType()); 821 int CallbackIdx = TypeSize == 8 ? 0 : 822 TypeSize == 16 ? 1 : 823 TypeSize == 32 ? 2 : 824 TypeSize == 64 ? 3 : -1; 825 if (CallbackIdx < 0) continue; 826 // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1); 827 auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx]; 828 bool FirstIsConst = isa<ConstantInt>(A0); 829 bool SecondIsConst = isa<ConstantInt>(A1); 830 // If both are const, then we don't need such a comparison. 831 if (FirstIsConst && SecondIsConst) continue; 832 // If only one is const, then make it the first callback argument. 833 if (FirstIsConst || SecondIsConst) { 834 CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx]; 835 if (SecondIsConst) 836 std::swap(A0, A1); 837 } 838 839 auto Ty = Type::getIntNTy(*C, TypeSize); 840 IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true), 841 IRB.CreateIntCast(A1, Ty, true)}); 842 } 843 } 844 } 845 846 void ModuleSanitizerCoverage::InjectCoverageAtBlock(Function &F, BasicBlock &BB, 847 size_t Idx, 848 bool IsLeafFunc) { 849 BasicBlock::iterator IP = BB.getFirstInsertionPt(); 850 bool IsEntryBB = &BB == &F.getEntryBlock(); 851 DebugLoc EntryLoc; 852 if (IsEntryBB) { 853 if (auto SP = F.getSubprogram()) 854 EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP); 855 // Keep static allocas and llvm.localescape calls in the entry block. Even 856 // if we aren't splitting the block, it's nice for allocas to be before 857 // calls. 858 IP = PrepareToSplitEntryBlock(BB, IP); 859 } else { 860 EntryLoc = IP->getDebugLoc(); 861 } 862 863 IRBuilder<> IRB(&*IP); 864 IRB.SetCurrentDebugLocation(EntryLoc); 865 if (Options.TracePC) { 866 IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC. 867 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge. 868 } 869 if (Options.TracePCGuard) { 870 auto GuardPtr = IRB.CreateIntToPtr( 871 IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy), 872 ConstantInt::get(IntptrTy, Idx * 4)), 873 Int32PtrTy); 874 IRB.CreateCall(SanCovTracePCGuard, GuardPtr); 875 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge. 876 } 877 if (Options.Inline8bitCounters) { 878 auto CounterPtr = IRB.CreateGEP( 879 Function8bitCounterArray->getValueType(), Function8bitCounterArray, 880 {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)}); 881 auto Load = IRB.CreateLoad(Int8Ty, CounterPtr); 882 auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1)); 883 auto Store = IRB.CreateStore(Inc, CounterPtr); 884 SetNoSanitizeMetadata(Load); 885 SetNoSanitizeMetadata(Store); 886 } 887 if (Options.StackDepth && IsEntryBB && !IsLeafFunc) { 888 // Check stack depth. If it's the deepest so far, record it. 889 Module *M = F.getParent(); 890 Function *GetFrameAddr = Intrinsic::getDeclaration( 891 M, Intrinsic::frameaddress, 892 IRB.getInt8PtrTy(M->getDataLayout().getAllocaAddrSpace())); 893 auto FrameAddrPtr = 894 IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)}); 895 auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy); 896 auto LowestStack = IRB.CreateLoad(IntptrTy, SanCovLowestStack); 897 auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack); 898 auto ThenTerm = SplitBlockAndInsertIfThen(IsStackLower, &*IP, false); 899 IRBuilder<> ThenIRB(ThenTerm); 900 auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack); 901 SetNoSanitizeMetadata(LowestStack); 902 SetNoSanitizeMetadata(Store); 903 } 904 } 905 906 std::string 907 ModuleSanitizerCoverage::getSectionName(const std::string &Section) const { 908 if (TargetTriple.isOSBinFormatCOFF()) { 909 if (Section == SanCovCountersSectionName) 910 return ".SCOV$CM"; 911 if (Section == SanCovPCsSectionName) 912 return ".SCOVP$M"; 913 return ".SCOV$GM"; // For SanCovGuardsSectionName. 914 } 915 if (TargetTriple.isOSBinFormatMachO()) 916 return "__DATA,__" + Section; 917 return "__" + Section; 918 } 919 920 std::string 921 ModuleSanitizerCoverage::getSectionStart(const std::string &Section) const { 922 if (TargetTriple.isOSBinFormatMachO()) 923 return "\1section$start$__DATA$__" + Section; 924 return "__start___" + Section; 925 } 926 927 std::string 928 ModuleSanitizerCoverage::getSectionEnd(const std::string &Section) const { 929 if (TargetTriple.isOSBinFormatMachO()) 930 return "\1section$end$__DATA$__" + Section; 931 return "__stop___" + Section; 932 } 933 934 char ModuleSanitizerCoverageLegacyPass::ID = 0; 935 INITIALIZE_PASS_BEGIN(ModuleSanitizerCoverageLegacyPass, "sancov", 936 "Pass for instrumenting coverage on functions", false, 937 false) 938 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) 939 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass) 940 INITIALIZE_PASS_END(ModuleSanitizerCoverageLegacyPass, "sancov", 941 "Pass for instrumenting coverage on functions", false, 942 false) 943 ModulePass *llvm::createModuleSanitizerCoverageLegacyPassPass( 944 const SanitizerCoverageOptions &Options) { 945 return new ModuleSanitizerCoverageLegacyPass(Options); 946 } 947