1 //===-- SanitizerCoverage.cpp - coverage instrumentation for sanitizers ---===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // Coverage instrumentation done on LLVM IR level, works with Sanitizers. 11 // 12 //===----------------------------------------------------------------------===// 13 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 SanCovModuleCtorName = "sancov.module_ctor"; 66 static const uint64_t SanCtorAndDtorPriority = 2; 67 68 static const char *const SanCovTracePCGuardName = 69 "__sanitizer_cov_trace_pc_guard"; 70 static const char *const SanCovTracePCGuardInitName = 71 "__sanitizer_cov_trace_pc_guard_init"; 72 static const char *const SanCov8bitCountersInitName = 73 "__sanitizer_cov_8bit_counters_init"; 74 static const char *const SanCovPCsInitName = "__sanitizer_cov_pcs_init"; 75 76 static const char *const SanCovGuardsSectionName = "sancov_guards"; 77 static const char *const SanCovCountersSectionName = "sancov_cntrs"; 78 static const char *const SanCovPCsSectionName = "sancov_pcs"; 79 80 static const char *const SanCovLowestStackName = "__sancov_lowest_stack"; 81 82 static cl::opt<int> ClCoverageLevel( 83 "sanitizer-coverage-level", 84 cl::desc("Sanitizer Coverage. 0: none, 1: entry block, 2: all blocks, " 85 "3: all blocks and critical edges"), 86 cl::Hidden, cl::init(0)); 87 88 static cl::opt<bool> ClTracePC("sanitizer-coverage-trace-pc", 89 cl::desc("Experimental pc tracing"), cl::Hidden, 90 cl::init(false)); 91 92 static cl::opt<bool> ClTracePCGuard("sanitizer-coverage-trace-pc-guard", 93 cl::desc("pc tracing with a guard"), 94 cl::Hidden, cl::init(false)); 95 96 // If true, we create a global variable that contains PCs of all instrumented 97 // BBs, put this global into a named section, and pass this section's bounds 98 // to __sanitizer_cov_pcs_init. 99 // This way the coverage instrumentation does not need to acquire the PCs 100 // at run-time. Works with trace-pc-guard and inline-8bit-counters. 101 static cl::opt<bool> ClCreatePCTable("sanitizer-coverage-pc-table", 102 cl::desc("create a static PC table"), 103 cl::Hidden, cl::init(false)); 104 105 static cl::opt<bool> 106 ClInline8bitCounters("sanitizer-coverage-inline-8bit-counters", 107 cl::desc("increments 8-bit counter for every edge"), 108 cl::Hidden, cl::init(false)); 109 110 static cl::opt<bool> 111 ClCMPTracing("sanitizer-coverage-trace-compares", 112 cl::desc("Tracing of CMP and similar instructions"), 113 cl::Hidden, cl::init(false)); 114 115 static cl::opt<bool> ClDIVTracing("sanitizer-coverage-trace-divs", 116 cl::desc("Tracing of DIV instructions"), 117 cl::Hidden, cl::init(false)); 118 119 static cl::opt<bool> ClGEPTracing("sanitizer-coverage-trace-geps", 120 cl::desc("Tracing of GEP instructions"), 121 cl::Hidden, cl::init(false)); 122 123 static cl::opt<bool> 124 ClPruneBlocks("sanitizer-coverage-prune-blocks", 125 cl::desc("Reduce the number of instrumented blocks"), 126 cl::Hidden, cl::init(true)); 127 128 static cl::opt<bool> ClStackDepth("sanitizer-coverage-stack-depth", 129 cl::desc("max stack depth tracing"), 130 cl::Hidden, cl::init(false)); 131 132 namespace { 133 134 SanitizerCoverageOptions getOptions(int LegacyCoverageLevel) { 135 SanitizerCoverageOptions Res; 136 switch (LegacyCoverageLevel) { 137 case 0: 138 Res.CoverageType = SanitizerCoverageOptions::SCK_None; 139 break; 140 case 1: 141 Res.CoverageType = SanitizerCoverageOptions::SCK_Function; 142 break; 143 case 2: 144 Res.CoverageType = SanitizerCoverageOptions::SCK_BB; 145 break; 146 case 3: 147 Res.CoverageType = SanitizerCoverageOptions::SCK_Edge; 148 break; 149 case 4: 150 Res.CoverageType = SanitizerCoverageOptions::SCK_Edge; 151 Res.IndirectCalls = true; 152 break; 153 } 154 return Res; 155 } 156 157 SanitizerCoverageOptions OverrideFromCL(SanitizerCoverageOptions Options) { 158 // Sets CoverageType and IndirectCalls. 159 SanitizerCoverageOptions CLOpts = getOptions(ClCoverageLevel); 160 Options.CoverageType = std::max(Options.CoverageType, CLOpts.CoverageType); 161 Options.IndirectCalls |= CLOpts.IndirectCalls; 162 Options.TraceCmp |= ClCMPTracing; 163 Options.TraceDiv |= ClDIVTracing; 164 Options.TraceGep |= ClGEPTracing; 165 Options.TracePC |= ClTracePC; 166 Options.TracePCGuard |= ClTracePCGuard; 167 Options.Inline8bitCounters |= ClInline8bitCounters; 168 Options.PCTable |= ClCreatePCTable; 169 Options.NoPrune |= !ClPruneBlocks; 170 Options.StackDepth |= ClStackDepth; 171 if (!Options.TracePCGuard && !Options.TracePC && 172 !Options.Inline8bitCounters && !Options.StackDepth) 173 Options.TracePCGuard = true; // TracePCGuard is default. 174 return Options; 175 } 176 177 class SanitizerCoverageModule : public ModulePass { 178 public: 179 SanitizerCoverageModule( 180 const SanitizerCoverageOptions &Options = SanitizerCoverageOptions()) 181 : ModulePass(ID), Options(OverrideFromCL(Options)) { 182 initializeSanitizerCoverageModulePass(*PassRegistry::getPassRegistry()); 183 } 184 bool runOnModule(Module &M) override; 185 bool runOnFunction(Function &F); 186 static char ID; // Pass identification, replacement for typeid 187 StringRef getPassName() const override { return "SanitizerCoverageModule"; } 188 189 void getAnalysisUsage(AnalysisUsage &AU) const override { 190 AU.addRequired<DominatorTreeWrapperPass>(); 191 AU.addRequired<PostDominatorTreeWrapperPass>(); 192 } 193 194 private: 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 *InitFunctionName, 214 Type *Ty, const char *Section); 215 std::pair<Value *, Value *> CreateSecStartEnd(Module &M, const char *Section, 216 Type *Ty); 217 218 void SetNoSanitizeMetadata(Instruction *I) { 219 I->setMetadata(I->getModule()->getMDKindID("nosanitize"), 220 MDNode::get(*C, None)); 221 } 222 223 std::string getSectionName(const std::string &Section) const; 224 std::string getSectionStart(const std::string &Section) const; 225 std::string getSectionEnd(const std::string &Section) const; 226 Function *SanCovTracePCIndir; 227 Function *SanCovTracePC, *SanCovTracePCGuard; 228 Function *SanCovTraceCmpFunction[4]; 229 Function *SanCovTraceConstCmpFunction[4]; 230 Function *SanCovTraceDivFunction[2]; 231 Function *SanCovTraceGepFunction; 232 Function *SanCovTraceSwitchFunction; 233 GlobalVariable *SanCovLowestStack; 234 InlineAsm *EmptyAsm; 235 Type *IntptrTy, *IntptrPtrTy, *Int64Ty, *Int64PtrTy, *Int32Ty, *Int32PtrTy, 236 *Int16Ty, *Int8Ty, *Int8PtrTy; 237 Module *CurModule; 238 std::string CurModuleUniqueId; 239 Triple TargetTriple; 240 LLVMContext *C; 241 const DataLayout *DL; 242 243 GlobalVariable *FunctionGuardArray; // for trace-pc-guard. 244 GlobalVariable *Function8bitCounterArray; // for inline-8bit-counters. 245 GlobalVariable *FunctionPCsArray; // for pc-table. 246 SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed; 247 SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed; 248 249 SanitizerCoverageOptions Options; 250 }; 251 252 } // namespace 253 254 std::pair<Value *, Value *> 255 SanitizerCoverageModule::CreateSecStartEnd(Module &M, const char *Section, 256 Type *Ty) { 257 GlobalVariable *SecStart = 258 new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage, nullptr, 259 getSectionStart(Section)); 260 SecStart->setVisibility(GlobalValue::HiddenVisibility); 261 GlobalVariable *SecEnd = 262 new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage, 263 nullptr, getSectionEnd(Section)); 264 SecEnd->setVisibility(GlobalValue::HiddenVisibility); 265 IRBuilder<> IRB(M.getContext()); 266 Value *SecEndPtr = IRB.CreatePointerCast(SecEnd, Ty); 267 if (TargetTriple.getObjectFormat() != Triple::COFF) 268 return std::make_pair(IRB.CreatePointerCast(SecStart, Ty), SecEndPtr); 269 270 // Account for the fact that on windows-msvc __start_* symbols actually 271 // point to a uint64_t before the start of the array. 272 auto SecStartI8Ptr = IRB.CreatePointerCast(SecStart, Int8PtrTy); 273 auto GEP = IRB.CreateGEP(SecStartI8Ptr, 274 ConstantInt::get(IntptrTy, sizeof(uint64_t))); 275 return std::make_pair(IRB.CreatePointerCast(GEP, Ty), SecEndPtr); 276 } 277 278 Function *SanitizerCoverageModule::CreateInitCallsForSections( 279 Module &M, const char *InitFunctionName, Type *Ty, 280 const char *Section) { 281 auto SecStartEnd = CreateSecStartEnd(M, Section, Ty); 282 auto SecStart = SecStartEnd.first; 283 auto SecEnd = SecStartEnd.second; 284 Function *CtorFunc; 285 std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions( 286 M, SanCovModuleCtorName, InitFunctionName, {Ty, Ty}, {SecStart, SecEnd}); 287 288 if (TargetTriple.supportsCOMDAT()) { 289 // Use comdat to dedup CtorFunc. 290 CtorFunc->setComdat(M.getOrInsertComdat(SanCovModuleCtorName)); 291 appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc); 292 } else { 293 appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority); 294 } 295 296 if (TargetTriple.getObjectFormat() == Triple::COFF) { 297 // In COFF files, if the contructors are set as COMDAT (they are because 298 // COFF supports COMDAT) and the linker flag /OPT:REF (strip unreferenced 299 // functions and data) is used, the constructors get stripped. To prevent 300 // this, give the constructors weak ODR linkage and tell the linker to 301 // always include the sancov constructor. This way the linker can 302 // deduplicate the constructors but always leave one copy. 303 CtorFunc->setLinkage(GlobalValue::WeakODRLinkage); 304 SmallString<20> PartialIncDirective("/include:"); 305 // Get constructor's mangled name in order to support i386. 306 SmallString<40> MangledName; 307 Mangler().getNameWithPrefix(MangledName, CtorFunc, true); 308 Twine IncDirective = PartialIncDirective + MangledName; 309 Metadata *Args[1] = {MDString::get(*C, IncDirective.str())}; 310 MDNode *MetadataNode = MDNode::get(*C, Args); 311 NamedMDNode *NamedMetadata = 312 M.getOrInsertNamedMetadata("llvm.linker.options"); 313 NamedMetadata->addOperand(MetadataNode); 314 } 315 return CtorFunc; 316 } 317 318 bool SanitizerCoverageModule::runOnModule(Module &M) { 319 if (Options.CoverageType == SanitizerCoverageOptions::SCK_None) 320 return false; 321 C = &(M.getContext()); 322 DL = &M.getDataLayout(); 323 CurModule = &M; 324 CurModuleUniqueId = getUniqueModuleId(CurModule); 325 TargetTriple = Triple(M.getTargetTriple()); 326 FunctionGuardArray = nullptr; 327 Function8bitCounterArray = nullptr; 328 FunctionPCsArray = nullptr; 329 IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits()); 330 IntptrPtrTy = PointerType::getUnqual(IntptrTy); 331 Type *VoidTy = Type::getVoidTy(*C); 332 IRBuilder<> IRB(*C); 333 Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty()); 334 Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty()); 335 Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty()); 336 Int64Ty = IRB.getInt64Ty(); 337 Int32Ty = IRB.getInt32Ty(); 338 Int16Ty = IRB.getInt16Ty(); 339 Int8Ty = IRB.getInt8Ty(); 340 341 SanCovTracePCIndir = checkSanitizerInterfaceFunction( 342 M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy)); 343 SanCovTraceCmpFunction[0] = 344 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 345 SanCovTraceCmp1, VoidTy, IRB.getInt8Ty(), IRB.getInt8Ty())); 346 SanCovTraceCmpFunction[1] = checkSanitizerInterfaceFunction( 347 M.getOrInsertFunction(SanCovTraceCmp2, VoidTy, IRB.getInt16Ty(), 348 IRB.getInt16Ty())); 349 SanCovTraceCmpFunction[2] = checkSanitizerInterfaceFunction( 350 M.getOrInsertFunction(SanCovTraceCmp4, VoidTy, IRB.getInt32Ty(), 351 IRB.getInt32Ty())); 352 SanCovTraceCmpFunction[3] = 353 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 354 SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty)); 355 356 SanCovTraceConstCmpFunction[0] = 357 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 358 SanCovTraceConstCmp1, VoidTy, Int8Ty, Int8Ty)); 359 SanCovTraceConstCmpFunction[1] = 360 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 361 SanCovTraceConstCmp2, VoidTy, Int16Ty, Int16Ty)); 362 SanCovTraceConstCmpFunction[2] = 363 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 364 SanCovTraceConstCmp4, VoidTy, Int32Ty, Int32Ty)); 365 SanCovTraceConstCmpFunction[3] = 366 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 367 SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty)); 368 369 SanCovTraceDivFunction[0] = 370 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 371 SanCovTraceDiv4, VoidTy, IRB.getInt32Ty())); 372 SanCovTraceDivFunction[1] = 373 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 374 SanCovTraceDiv8, VoidTy, Int64Ty)); 375 SanCovTraceGepFunction = 376 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 377 SanCovTraceGep, VoidTy, IntptrTy)); 378 SanCovTraceSwitchFunction = 379 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 380 SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy)); 381 382 Constant *SanCovLowestStackConstant = 383 M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy); 384 SanCovLowestStack = cast<GlobalVariable>(SanCovLowestStackConstant); 385 SanCovLowestStack->setThreadLocalMode( 386 GlobalValue::ThreadLocalMode::InitialExecTLSModel); 387 if (Options.StackDepth && !SanCovLowestStack->isDeclaration()) 388 SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy)); 389 390 // Make sure smaller parameters are zero-extended to i64 as required by the 391 // x86_64 ABI. 392 if (TargetTriple.getArch() == Triple::x86_64) { 393 for (int i = 0; i < 3; i++) { 394 SanCovTraceCmpFunction[i]->addParamAttr(0, Attribute::ZExt); 395 SanCovTraceCmpFunction[i]->addParamAttr(1, Attribute::ZExt); 396 SanCovTraceConstCmpFunction[i]->addParamAttr(0, Attribute::ZExt); 397 SanCovTraceConstCmpFunction[i]->addParamAttr(1, Attribute::ZExt); 398 } 399 SanCovTraceDivFunction[0]->addParamAttr(0, Attribute::ZExt); 400 } 401 402 403 // We insert an empty inline asm after cov callbacks to avoid callback merge. 404 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false), 405 StringRef(""), StringRef(""), 406 /*hasSideEffects=*/true); 407 408 SanCovTracePC = checkSanitizerInterfaceFunction( 409 M.getOrInsertFunction(SanCovTracePCName, VoidTy)); 410 SanCovTracePCGuard = checkSanitizerInterfaceFunction(M.getOrInsertFunction( 411 SanCovTracePCGuardName, VoidTy, Int32PtrTy)); 412 413 for (auto &F : M) 414 runOnFunction(F); 415 416 Function *Ctor = nullptr; 417 418 if (FunctionGuardArray) 419 Ctor = CreateInitCallsForSections(M, SanCovTracePCGuardInitName, Int32PtrTy, 420 SanCovGuardsSectionName); 421 if (Function8bitCounterArray) 422 Ctor = CreateInitCallsForSections(M, SanCov8bitCountersInitName, Int8PtrTy, 423 SanCovCountersSectionName); 424 if (Ctor && Options.PCTable) { 425 auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrPtrTy); 426 Function *InitFunction = declareSanitizerInitFunction( 427 M, SanCovPCsInitName, {IntptrPtrTy, IntptrPtrTy}); 428 IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator()); 429 IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second}); 430 } 431 // We don't reference these arrays directly in any of our runtime functions, 432 // so we need to prevent them from being dead stripped. 433 if (TargetTriple.isOSBinFormatMachO()) 434 appendToUsed(M, GlobalsToAppendToUsed); 435 appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed); 436 return true; 437 } 438 439 // True if block has successors and it dominates all of them. 440 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) { 441 if (succ_begin(BB) == succ_end(BB)) 442 return false; 443 444 for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) { 445 if (!DT->dominates(BB, SUCC)) 446 return false; 447 } 448 449 return true; 450 } 451 452 // True if block has predecessors and it postdominates all of them. 453 static bool isFullPostDominator(const BasicBlock *BB, 454 const PostDominatorTree *PDT) { 455 if (pred_begin(BB) == pred_end(BB)) 456 return false; 457 458 for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) { 459 if (!PDT->dominates(BB, PRED)) 460 return false; 461 } 462 463 return true; 464 } 465 466 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB, 467 const DominatorTree *DT, 468 const PostDominatorTree *PDT, 469 const SanitizerCoverageOptions &Options) { 470 // Don't insert coverage for unreachable blocks: we will never call 471 // __sanitizer_cov() for them, so counting them in 472 // NumberOfInstrumentedBlocks() might complicate calculation of code coverage 473 // percentage. Also, unreachable instructions frequently have no debug 474 // locations. 475 if (isa<UnreachableInst>(BB->getTerminator())) 476 return false; 477 478 // Don't insert coverage into blocks without a valid insertion point 479 // (catchswitch blocks). 480 if (BB->getFirstInsertionPt() == BB->end()) 481 return false; 482 483 if (Options.NoPrune || &F.getEntryBlock() == BB) 484 return true; 485 486 if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function && 487 &F.getEntryBlock() != BB) 488 return false; 489 490 // Do not instrument full dominators, or full post-dominators with multiple 491 // predecessors. 492 return !isFullDominator(BB, DT) 493 && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor()); 494 } 495 496 bool SanitizerCoverageModule::runOnFunction(Function &F) { 497 if (F.empty()) 498 return false; 499 if (F.getName().find(".module_ctor") != std::string::npos) 500 return false; // Should not instrument sanitizer init functions. 501 if (F.getName().startswith("__sanitizer_")) 502 return false; // Don't instrument __sanitizer_* callbacks. 503 // Don't touch available_externally functions, their actual body is elewhere. 504 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) 505 return false; 506 // Don't instrument MSVC CRT configuration helpers. They may run before normal 507 // initialization. 508 if (F.getName() == "__local_stdio_printf_options" || 509 F.getName() == "__local_stdio_scanf_options") 510 return false; 511 if (isa<UnreachableInst>(F.getEntryBlock().getTerminator())) 512 return false; 513 // Don't instrument functions using SEH for now. Splitting basic blocks like 514 // we do for coverage breaks WinEHPrepare. 515 // FIXME: Remove this when SEH no longer uses landingpad pattern matching. 516 if (F.hasPersonalityFn() && 517 isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn()))) 518 return false; 519 if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge) 520 SplitAllCriticalEdges(F); 521 SmallVector<Instruction *, 8> IndirCalls; 522 SmallVector<BasicBlock *, 16> BlocksToInstrument; 523 SmallVector<Instruction *, 8> CmpTraceTargets; 524 SmallVector<Instruction *, 8> SwitchTraceTargets; 525 SmallVector<BinaryOperator *, 8> DivTraceTargets; 526 SmallVector<GetElementPtrInst *, 8> GepTraceTargets; 527 528 const DominatorTree *DT = 529 &getAnalysis<DominatorTreeWrapperPass>(F).getDomTree(); 530 const PostDominatorTree *PDT = 531 &getAnalysis<PostDominatorTreeWrapperPass>(F).getPostDomTree(); 532 bool IsLeafFunc = true; 533 534 for (auto &BB : F) { 535 if (shouldInstrumentBlock(F, &BB, DT, PDT, Options)) 536 BlocksToInstrument.push_back(&BB); 537 for (auto &Inst : BB) { 538 if (Options.IndirectCalls) { 539 CallSite CS(&Inst); 540 if (CS && !CS.getCalledFunction()) 541 IndirCalls.push_back(&Inst); 542 } 543 if (Options.TraceCmp) { 544 if (isa<ICmpInst>(&Inst)) 545 CmpTraceTargets.push_back(&Inst); 546 if (isa<SwitchInst>(&Inst)) 547 SwitchTraceTargets.push_back(&Inst); 548 } 549 if (Options.TraceDiv) 550 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst)) 551 if (BO->getOpcode() == Instruction::SDiv || 552 BO->getOpcode() == Instruction::UDiv) 553 DivTraceTargets.push_back(BO); 554 if (Options.TraceGep) 555 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst)) 556 GepTraceTargets.push_back(GEP); 557 if (Options.StackDepth) 558 if (isa<InvokeInst>(Inst) || 559 (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst))) 560 IsLeafFunc = false; 561 } 562 } 563 564 InjectCoverage(F, BlocksToInstrument, IsLeafFunc); 565 InjectCoverageForIndirectCalls(F, IndirCalls); 566 InjectTraceForCmp(F, CmpTraceTargets); 567 InjectTraceForSwitch(F, SwitchTraceTargets); 568 InjectTraceForDiv(F, DivTraceTargets); 569 InjectTraceForGep(F, GepTraceTargets); 570 return true; 571 } 572 573 GlobalVariable *SanitizerCoverageModule::CreateFunctionLocalArrayInSection( 574 size_t NumElements, Function &F, Type *Ty, const char *Section) { 575 ArrayType *ArrayTy = ArrayType::get(Ty, NumElements); 576 auto Array = new GlobalVariable( 577 *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage, 578 Constant::getNullValue(ArrayTy), "__sancov_gen_"); 579 580 if (TargetTriple.supportsCOMDAT()) 581 if (auto Comdat = 582 GetOrCreateFunctionComdat(F, TargetTriple, CurModuleUniqueId)) 583 Array->setComdat(Comdat); 584 Array->setSection(getSectionName(Section)); 585 Array->setAlignment(Ty->isPointerTy() ? DL->getPointerSize() 586 : Ty->getPrimitiveSizeInBits() / 8); 587 GlobalsToAppendToUsed.push_back(Array); 588 GlobalsToAppendToCompilerUsed.push_back(Array); 589 MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F)); 590 Array->addMetadata(LLVMContext::MD_associated, *MD); 591 592 return Array; 593 } 594 595 GlobalVariable * 596 SanitizerCoverageModule::CreatePCArray(Function &F, 597 ArrayRef<BasicBlock *> AllBlocks) { 598 size_t N = AllBlocks.size(); 599 assert(N); 600 SmallVector<Constant *, 32> PCs; 601 IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt()); 602 for (size_t i = 0; i < N; i++) { 603 if (&F.getEntryBlock() == AllBlocks[i]) { 604 PCs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy)); 605 PCs.push_back((Constant *)IRB.CreateIntToPtr( 606 ConstantInt::get(IntptrTy, 1), IntptrPtrTy)); 607 } else { 608 PCs.push_back((Constant *)IRB.CreatePointerCast( 609 BlockAddress::get(AllBlocks[i]), IntptrPtrTy)); 610 PCs.push_back((Constant *)IRB.CreateIntToPtr( 611 ConstantInt::get(IntptrTy, 0), IntptrPtrTy)); 612 } 613 } 614 auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, IntptrPtrTy, 615 SanCovPCsSectionName); 616 PCArray->setInitializer( 617 ConstantArray::get(ArrayType::get(IntptrPtrTy, N * 2), PCs)); 618 PCArray->setConstant(true); 619 620 return PCArray; 621 } 622 623 void SanitizerCoverageModule::CreateFunctionLocalArrays( 624 Function &F, ArrayRef<BasicBlock *> AllBlocks) { 625 if (Options.TracePCGuard) 626 FunctionGuardArray = CreateFunctionLocalArrayInSection( 627 AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName); 628 629 if (Options.Inline8bitCounters) 630 Function8bitCounterArray = CreateFunctionLocalArrayInSection( 631 AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName); 632 633 if (Options.PCTable) 634 FunctionPCsArray = CreatePCArray(F, AllBlocks); 635 } 636 637 bool SanitizerCoverageModule::InjectCoverage(Function &F, 638 ArrayRef<BasicBlock *> AllBlocks, 639 bool IsLeafFunc) { 640 if (AllBlocks.empty()) return false; 641 CreateFunctionLocalArrays(F, AllBlocks); 642 for (size_t i = 0, N = AllBlocks.size(); i < N; i++) 643 InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc); 644 return true; 645 } 646 647 // On every indirect call we call a run-time function 648 // __sanitizer_cov_indir_call* with two parameters: 649 // - callee address, 650 // - global cache array that contains CacheSize pointers (zero-initialized). 651 // The cache is used to speed up recording the caller-callee pairs. 652 // The address of the caller is passed implicitly via caller PC. 653 // CacheSize is encoded in the name of the run-time function. 654 void SanitizerCoverageModule::InjectCoverageForIndirectCalls( 655 Function &F, ArrayRef<Instruction *> IndirCalls) { 656 if (IndirCalls.empty()) 657 return; 658 assert(Options.TracePC || Options.TracePCGuard || Options.Inline8bitCounters); 659 for (auto I : IndirCalls) { 660 IRBuilder<> IRB(I); 661 CallSite CS(I); 662 Value *Callee = CS.getCalledValue(); 663 if (isa<InlineAsm>(Callee)) 664 continue; 665 IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy)); 666 } 667 } 668 669 // For every switch statement we insert a call: 670 // __sanitizer_cov_trace_switch(CondValue, 671 // {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... }) 672 673 void SanitizerCoverageModule::InjectTraceForSwitch( 674 Function &, ArrayRef<Instruction *> SwitchTraceTargets) { 675 for (auto I : SwitchTraceTargets) { 676 if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) { 677 IRBuilder<> IRB(I); 678 SmallVector<Constant *, 16> Initializers; 679 Value *Cond = SI->getCondition(); 680 if (Cond->getType()->getScalarSizeInBits() > 681 Int64Ty->getScalarSizeInBits()) 682 continue; 683 Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases())); 684 Initializers.push_back( 685 ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits())); 686 if (Cond->getType()->getScalarSizeInBits() < 687 Int64Ty->getScalarSizeInBits()) 688 Cond = IRB.CreateIntCast(Cond, Int64Ty, false); 689 for (auto It : SI->cases()) { 690 Constant *C = It.getCaseValue(); 691 if (C->getType()->getScalarSizeInBits() < 692 Int64Ty->getScalarSizeInBits()) 693 C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty); 694 Initializers.push_back(C); 695 } 696 llvm::sort(Initializers.begin() + 2, Initializers.end(), 697 [](const Constant *A, const Constant *B) { 698 return cast<ConstantInt>(A)->getLimitedValue() < 699 cast<ConstantInt>(B)->getLimitedValue(); 700 }); 701 ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size()); 702 GlobalVariable *GV = new GlobalVariable( 703 *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage, 704 ConstantArray::get(ArrayOfInt64Ty, Initializers), 705 "__sancov_gen_cov_switch_values"); 706 IRB.CreateCall(SanCovTraceSwitchFunction, 707 {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)}); 708 } 709 } 710 } 711 712 void SanitizerCoverageModule::InjectTraceForDiv( 713 Function &, ArrayRef<BinaryOperator *> DivTraceTargets) { 714 for (auto BO : DivTraceTargets) { 715 IRBuilder<> IRB(BO); 716 Value *A1 = BO->getOperand(1); 717 if (isa<ConstantInt>(A1)) continue; 718 if (!A1->getType()->isIntegerTy()) 719 continue; 720 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType()); 721 int CallbackIdx = TypeSize == 32 ? 0 : 722 TypeSize == 64 ? 1 : -1; 723 if (CallbackIdx < 0) continue; 724 auto Ty = Type::getIntNTy(*C, TypeSize); 725 IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx], 726 {IRB.CreateIntCast(A1, Ty, true)}); 727 } 728 } 729 730 void SanitizerCoverageModule::InjectTraceForGep( 731 Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) { 732 for (auto GEP : GepTraceTargets) { 733 IRBuilder<> IRB(GEP); 734 for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I) 735 if (!isa<ConstantInt>(*I) && (*I)->getType()->isIntegerTy()) 736 IRB.CreateCall(SanCovTraceGepFunction, 737 {IRB.CreateIntCast(*I, IntptrTy, true)}); 738 } 739 } 740 741 void SanitizerCoverageModule::InjectTraceForCmp( 742 Function &, ArrayRef<Instruction *> CmpTraceTargets) { 743 for (auto I : CmpTraceTargets) { 744 if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) { 745 IRBuilder<> IRB(ICMP); 746 Value *A0 = ICMP->getOperand(0); 747 Value *A1 = ICMP->getOperand(1); 748 if (!A0->getType()->isIntegerTy()) 749 continue; 750 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType()); 751 int CallbackIdx = TypeSize == 8 ? 0 : 752 TypeSize == 16 ? 1 : 753 TypeSize == 32 ? 2 : 754 TypeSize == 64 ? 3 : -1; 755 if (CallbackIdx < 0) continue; 756 // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1); 757 auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx]; 758 bool FirstIsConst = isa<ConstantInt>(A0); 759 bool SecondIsConst = isa<ConstantInt>(A1); 760 // If both are const, then we don't need such a comparison. 761 if (FirstIsConst && SecondIsConst) continue; 762 // If only one is const, then make it the first callback argument. 763 if (FirstIsConst || SecondIsConst) { 764 CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx]; 765 if (SecondIsConst) 766 std::swap(A0, A1); 767 } 768 769 auto Ty = Type::getIntNTy(*C, TypeSize); 770 IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true), 771 IRB.CreateIntCast(A1, Ty, true)}); 772 } 773 } 774 } 775 776 void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB, 777 size_t Idx, 778 bool IsLeafFunc) { 779 BasicBlock::iterator IP = BB.getFirstInsertionPt(); 780 bool IsEntryBB = &BB == &F.getEntryBlock(); 781 DebugLoc EntryLoc; 782 if (IsEntryBB) { 783 if (auto SP = F.getSubprogram()) 784 EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP); 785 // Keep static allocas and llvm.localescape calls in the entry block. Even 786 // if we aren't splitting the block, it's nice for allocas to be before 787 // calls. 788 IP = PrepareToSplitEntryBlock(BB, IP); 789 } else { 790 EntryLoc = IP->getDebugLoc(); 791 } 792 793 IRBuilder<> IRB(&*IP); 794 IRB.SetCurrentDebugLocation(EntryLoc); 795 if (Options.TracePC) { 796 IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC. 797 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge. 798 } 799 if (Options.TracePCGuard) { 800 auto GuardPtr = IRB.CreateIntToPtr( 801 IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy), 802 ConstantInt::get(IntptrTy, Idx * 4)), 803 Int32PtrTy); 804 IRB.CreateCall(SanCovTracePCGuard, GuardPtr); 805 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge. 806 } 807 if (Options.Inline8bitCounters) { 808 auto CounterPtr = IRB.CreateGEP( 809 Function8bitCounterArray, 810 {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)}); 811 auto Load = IRB.CreateLoad(CounterPtr); 812 auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1)); 813 auto Store = IRB.CreateStore(Inc, CounterPtr); 814 SetNoSanitizeMetadata(Load); 815 SetNoSanitizeMetadata(Store); 816 } 817 if (Options.StackDepth && IsEntryBB && !IsLeafFunc) { 818 // Check stack depth. If it's the deepest so far, record it. 819 Function *GetFrameAddr = 820 Intrinsic::getDeclaration(F.getParent(), Intrinsic::frameaddress); 821 auto FrameAddrPtr = 822 IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)}); 823 auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy); 824 auto LowestStack = IRB.CreateLoad(SanCovLowestStack); 825 auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack); 826 auto ThenTerm = SplitBlockAndInsertIfThen(IsStackLower, &*IP, false); 827 IRBuilder<> ThenIRB(ThenTerm); 828 auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack); 829 SetNoSanitizeMetadata(LowestStack); 830 SetNoSanitizeMetadata(Store); 831 } 832 } 833 834 std::string 835 SanitizerCoverageModule::getSectionName(const std::string &Section) const { 836 if (TargetTriple.getObjectFormat() == Triple::COFF) { 837 if (Section == SanCovCountersSectionName) 838 return ".SCOV$CM"; 839 if (Section == SanCovPCsSectionName) 840 return ".SCOVP$M"; 841 return ".SCOV$GM"; // For SanCovGuardsSectionName. 842 } 843 if (TargetTriple.isOSBinFormatMachO()) 844 return "__DATA,__" + Section; 845 return "__" + Section; 846 } 847 848 std::string 849 SanitizerCoverageModule::getSectionStart(const std::string &Section) const { 850 if (TargetTriple.isOSBinFormatMachO()) 851 return "\1section$start$__DATA$__" + Section; 852 return "__start___" + Section; 853 } 854 855 std::string 856 SanitizerCoverageModule::getSectionEnd(const std::string &Section) const { 857 if (TargetTriple.isOSBinFormatMachO()) 858 return "\1section$end$__DATA$__" + Section; 859 return "__stop___" + Section; 860 } 861 862 863 char SanitizerCoverageModule::ID = 0; 864 INITIALIZE_PASS_BEGIN(SanitizerCoverageModule, "sancov", 865 "SanitizerCoverage: TODO." 866 "ModulePass", 867 false, false) 868 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) 869 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass) 870 INITIALIZE_PASS_END(SanitizerCoverageModule, "sancov", 871 "SanitizerCoverage: TODO." 872 "ModulePass", 873 false, false) 874 ModulePass *llvm::createSanitizerCoverageModulePass( 875 const SanitizerCoverageOptions &Options) { 876 return new SanitizerCoverageModule(Options); 877 } 878