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.isOSBinFormatCOFF()) 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.isOSBinFormatCOFF()) { 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 ensure the linker knows 301 // to include the sancov constructor. This way the linker can deduplicate 302 // the constructors but always leave one copy. 303 CtorFunc->setLinkage(GlobalValue::WeakODRLinkage); 304 appendToUsed(M, CtorFunc); 305 } 306 return CtorFunc; 307 } 308 309 bool SanitizerCoverageModule::runOnModule(Module &M) { 310 if (Options.CoverageType == SanitizerCoverageOptions::SCK_None) 311 return false; 312 C = &(M.getContext()); 313 DL = &M.getDataLayout(); 314 CurModule = &M; 315 CurModuleUniqueId = getUniqueModuleId(CurModule); 316 TargetTriple = Triple(M.getTargetTriple()); 317 FunctionGuardArray = nullptr; 318 Function8bitCounterArray = nullptr; 319 FunctionPCsArray = nullptr; 320 IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits()); 321 IntptrPtrTy = PointerType::getUnqual(IntptrTy); 322 Type *VoidTy = Type::getVoidTy(*C); 323 IRBuilder<> IRB(*C); 324 Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty()); 325 Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty()); 326 Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty()); 327 Int64Ty = IRB.getInt64Ty(); 328 Int32Ty = IRB.getInt32Ty(); 329 Int16Ty = IRB.getInt16Ty(); 330 Int8Ty = IRB.getInt8Ty(); 331 332 SanCovTracePCIndir = checkSanitizerInterfaceFunction( 333 M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy)); 334 SanCovTraceCmpFunction[0] = 335 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 336 SanCovTraceCmp1, VoidTy, IRB.getInt8Ty(), IRB.getInt8Ty())); 337 SanCovTraceCmpFunction[1] = checkSanitizerInterfaceFunction( 338 M.getOrInsertFunction(SanCovTraceCmp2, VoidTy, IRB.getInt16Ty(), 339 IRB.getInt16Ty())); 340 SanCovTraceCmpFunction[2] = checkSanitizerInterfaceFunction( 341 M.getOrInsertFunction(SanCovTraceCmp4, VoidTy, IRB.getInt32Ty(), 342 IRB.getInt32Ty())); 343 SanCovTraceCmpFunction[3] = 344 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 345 SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty)); 346 347 SanCovTraceConstCmpFunction[0] = 348 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 349 SanCovTraceConstCmp1, VoidTy, Int8Ty, Int8Ty)); 350 SanCovTraceConstCmpFunction[1] = 351 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 352 SanCovTraceConstCmp2, VoidTy, Int16Ty, Int16Ty)); 353 SanCovTraceConstCmpFunction[2] = 354 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 355 SanCovTraceConstCmp4, VoidTy, Int32Ty, Int32Ty)); 356 SanCovTraceConstCmpFunction[3] = 357 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 358 SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty)); 359 360 SanCovTraceDivFunction[0] = 361 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 362 SanCovTraceDiv4, VoidTy, IRB.getInt32Ty())); 363 SanCovTraceDivFunction[1] = 364 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 365 SanCovTraceDiv8, VoidTy, Int64Ty)); 366 SanCovTraceGepFunction = 367 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 368 SanCovTraceGep, VoidTy, IntptrTy)); 369 SanCovTraceSwitchFunction = 370 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 371 SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy)); 372 373 Constant *SanCovLowestStackConstant = 374 M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy); 375 SanCovLowestStack = cast<GlobalVariable>(SanCovLowestStackConstant); 376 SanCovLowestStack->setThreadLocalMode( 377 GlobalValue::ThreadLocalMode::InitialExecTLSModel); 378 if (Options.StackDepth && !SanCovLowestStack->isDeclaration()) 379 SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy)); 380 381 // Make sure smaller parameters are zero-extended to i64 as required by the 382 // x86_64 ABI. 383 if (TargetTriple.getArch() == Triple::x86_64) { 384 for (int i = 0; i < 3; i++) { 385 SanCovTraceCmpFunction[i]->addParamAttr(0, Attribute::ZExt); 386 SanCovTraceCmpFunction[i]->addParamAttr(1, Attribute::ZExt); 387 SanCovTraceConstCmpFunction[i]->addParamAttr(0, Attribute::ZExt); 388 SanCovTraceConstCmpFunction[i]->addParamAttr(1, Attribute::ZExt); 389 } 390 SanCovTraceDivFunction[0]->addParamAttr(0, Attribute::ZExt); 391 } 392 393 394 // We insert an empty inline asm after cov callbacks to avoid callback merge. 395 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false), 396 StringRef(""), StringRef(""), 397 /*hasSideEffects=*/true); 398 399 SanCovTracePC = checkSanitizerInterfaceFunction( 400 M.getOrInsertFunction(SanCovTracePCName, VoidTy)); 401 SanCovTracePCGuard = checkSanitizerInterfaceFunction(M.getOrInsertFunction( 402 SanCovTracePCGuardName, VoidTy, Int32PtrTy)); 403 404 for (auto &F : M) 405 runOnFunction(F); 406 407 Function *Ctor = nullptr; 408 409 if (FunctionGuardArray) 410 Ctor = CreateInitCallsForSections(M, SanCovTracePCGuardInitName, Int32PtrTy, 411 SanCovGuardsSectionName); 412 if (Function8bitCounterArray) 413 Ctor = CreateInitCallsForSections(M, SanCov8bitCountersInitName, Int8PtrTy, 414 SanCovCountersSectionName); 415 if (Ctor && Options.PCTable) { 416 auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrPtrTy); 417 Function *InitFunction = declareSanitizerInitFunction( 418 M, SanCovPCsInitName, {IntptrPtrTy, IntptrPtrTy}); 419 IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator()); 420 IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second}); 421 } 422 // We don't reference these arrays directly in any of our runtime functions, 423 // so we need to prevent them from being dead stripped. 424 if (TargetTriple.isOSBinFormatMachO()) 425 appendToUsed(M, GlobalsToAppendToUsed); 426 appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed); 427 return true; 428 } 429 430 // True if block has successors and it dominates all of them. 431 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) { 432 if (succ_begin(BB) == succ_end(BB)) 433 return false; 434 435 for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) { 436 if (!DT->dominates(BB, SUCC)) 437 return false; 438 } 439 440 return true; 441 } 442 443 // True if block has predecessors and it postdominates all of them. 444 static bool isFullPostDominator(const BasicBlock *BB, 445 const PostDominatorTree *PDT) { 446 if (pred_begin(BB) == pred_end(BB)) 447 return false; 448 449 for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) { 450 if (!PDT->dominates(BB, PRED)) 451 return false; 452 } 453 454 return true; 455 } 456 457 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB, 458 const DominatorTree *DT, 459 const PostDominatorTree *PDT, 460 const SanitizerCoverageOptions &Options) { 461 // Don't insert coverage for unreachable blocks: we will never call 462 // __sanitizer_cov() for them, so counting them in 463 // NumberOfInstrumentedBlocks() might complicate calculation of code coverage 464 // percentage. Also, unreachable instructions frequently have no debug 465 // locations. 466 if (isa<UnreachableInst>(BB->getTerminator())) 467 return false; 468 469 // Don't insert coverage into blocks without a valid insertion point 470 // (catchswitch blocks). 471 if (BB->getFirstInsertionPt() == BB->end()) 472 return false; 473 474 if (Options.NoPrune || &F.getEntryBlock() == BB) 475 return true; 476 477 if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function && 478 &F.getEntryBlock() != BB) 479 return false; 480 481 // Do not instrument full dominators, or full post-dominators with multiple 482 // predecessors. 483 return !isFullDominator(BB, DT) 484 && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor()); 485 } 486 487 bool SanitizerCoverageModule::runOnFunction(Function &F) { 488 if (F.empty()) 489 return false; 490 if (F.getName().find(".module_ctor") != std::string::npos) 491 return false; // Should not instrument sanitizer init functions. 492 if (F.getName().startswith("__sanitizer_")) 493 return false; // Don't instrument __sanitizer_* callbacks. 494 // Don't touch available_externally functions, their actual body is elewhere. 495 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) 496 return false; 497 // Don't instrument MSVC CRT configuration helpers. They may run before normal 498 // initialization. 499 if (F.getName() == "__local_stdio_printf_options" || 500 F.getName() == "__local_stdio_scanf_options") 501 return false; 502 if (isa<UnreachableInst>(F.getEntryBlock().getTerminator())) 503 return false; 504 // Don't instrument functions using SEH for now. Splitting basic blocks like 505 // we do for coverage breaks WinEHPrepare. 506 // FIXME: Remove this when SEH no longer uses landingpad pattern matching. 507 if (F.hasPersonalityFn() && 508 isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn()))) 509 return false; 510 if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge) 511 SplitAllCriticalEdges(F); 512 SmallVector<Instruction *, 8> IndirCalls; 513 SmallVector<BasicBlock *, 16> BlocksToInstrument; 514 SmallVector<Instruction *, 8> CmpTraceTargets; 515 SmallVector<Instruction *, 8> SwitchTraceTargets; 516 SmallVector<BinaryOperator *, 8> DivTraceTargets; 517 SmallVector<GetElementPtrInst *, 8> GepTraceTargets; 518 519 const DominatorTree *DT = 520 &getAnalysis<DominatorTreeWrapperPass>(F).getDomTree(); 521 const PostDominatorTree *PDT = 522 &getAnalysis<PostDominatorTreeWrapperPass>(F).getPostDomTree(); 523 bool IsLeafFunc = true; 524 525 for (auto &BB : F) { 526 if (shouldInstrumentBlock(F, &BB, DT, PDT, Options)) 527 BlocksToInstrument.push_back(&BB); 528 for (auto &Inst : BB) { 529 if (Options.IndirectCalls) { 530 CallSite CS(&Inst); 531 if (CS && !CS.getCalledFunction()) 532 IndirCalls.push_back(&Inst); 533 } 534 if (Options.TraceCmp) { 535 if (isa<ICmpInst>(&Inst)) 536 CmpTraceTargets.push_back(&Inst); 537 if (isa<SwitchInst>(&Inst)) 538 SwitchTraceTargets.push_back(&Inst); 539 } 540 if (Options.TraceDiv) 541 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst)) 542 if (BO->getOpcode() == Instruction::SDiv || 543 BO->getOpcode() == Instruction::UDiv) 544 DivTraceTargets.push_back(BO); 545 if (Options.TraceGep) 546 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst)) 547 GepTraceTargets.push_back(GEP); 548 if (Options.StackDepth) 549 if (isa<InvokeInst>(Inst) || 550 (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst))) 551 IsLeafFunc = false; 552 } 553 } 554 555 InjectCoverage(F, BlocksToInstrument, IsLeafFunc); 556 InjectCoverageForIndirectCalls(F, IndirCalls); 557 InjectTraceForCmp(F, CmpTraceTargets); 558 InjectTraceForSwitch(F, SwitchTraceTargets); 559 InjectTraceForDiv(F, DivTraceTargets); 560 InjectTraceForGep(F, GepTraceTargets); 561 return true; 562 } 563 564 GlobalVariable *SanitizerCoverageModule::CreateFunctionLocalArrayInSection( 565 size_t NumElements, Function &F, Type *Ty, const char *Section) { 566 ArrayType *ArrayTy = ArrayType::get(Ty, NumElements); 567 auto Array = new GlobalVariable( 568 *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage, 569 Constant::getNullValue(ArrayTy), "__sancov_gen_"); 570 571 if (TargetTriple.supportsCOMDAT()) 572 if (auto Comdat = 573 GetOrCreateFunctionComdat(F, TargetTriple, CurModuleUniqueId)) 574 Array->setComdat(Comdat); 575 Array->setSection(getSectionName(Section)); 576 Array->setAlignment(Ty->isPointerTy() ? DL->getPointerSize() 577 : Ty->getPrimitiveSizeInBits() / 8); 578 GlobalsToAppendToUsed.push_back(Array); 579 GlobalsToAppendToCompilerUsed.push_back(Array); 580 MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F)); 581 Array->addMetadata(LLVMContext::MD_associated, *MD); 582 583 return Array; 584 } 585 586 GlobalVariable * 587 SanitizerCoverageModule::CreatePCArray(Function &F, 588 ArrayRef<BasicBlock *> AllBlocks) { 589 size_t N = AllBlocks.size(); 590 assert(N); 591 SmallVector<Constant *, 32> PCs; 592 IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt()); 593 for (size_t i = 0; i < N; i++) { 594 if (&F.getEntryBlock() == AllBlocks[i]) { 595 PCs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy)); 596 PCs.push_back((Constant *)IRB.CreateIntToPtr( 597 ConstantInt::get(IntptrTy, 1), IntptrPtrTy)); 598 } else { 599 PCs.push_back((Constant *)IRB.CreatePointerCast( 600 BlockAddress::get(AllBlocks[i]), IntptrPtrTy)); 601 PCs.push_back((Constant *)IRB.CreateIntToPtr( 602 ConstantInt::get(IntptrTy, 0), IntptrPtrTy)); 603 } 604 } 605 auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, IntptrPtrTy, 606 SanCovPCsSectionName); 607 PCArray->setInitializer( 608 ConstantArray::get(ArrayType::get(IntptrPtrTy, N * 2), PCs)); 609 PCArray->setConstant(true); 610 611 return PCArray; 612 } 613 614 void SanitizerCoverageModule::CreateFunctionLocalArrays( 615 Function &F, ArrayRef<BasicBlock *> AllBlocks) { 616 if (Options.TracePCGuard) 617 FunctionGuardArray = CreateFunctionLocalArrayInSection( 618 AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName); 619 620 if (Options.Inline8bitCounters) 621 Function8bitCounterArray = CreateFunctionLocalArrayInSection( 622 AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName); 623 624 if (Options.PCTable) 625 FunctionPCsArray = CreatePCArray(F, AllBlocks); 626 } 627 628 bool SanitizerCoverageModule::InjectCoverage(Function &F, 629 ArrayRef<BasicBlock *> AllBlocks, 630 bool IsLeafFunc) { 631 if (AllBlocks.empty()) return false; 632 CreateFunctionLocalArrays(F, AllBlocks); 633 for (size_t i = 0, N = AllBlocks.size(); i < N; i++) 634 InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc); 635 return true; 636 } 637 638 // On every indirect call we call a run-time function 639 // __sanitizer_cov_indir_call* with two parameters: 640 // - callee address, 641 // - global cache array that contains CacheSize pointers (zero-initialized). 642 // The cache is used to speed up recording the caller-callee pairs. 643 // The address of the caller is passed implicitly via caller PC. 644 // CacheSize is encoded in the name of the run-time function. 645 void SanitizerCoverageModule::InjectCoverageForIndirectCalls( 646 Function &F, ArrayRef<Instruction *> IndirCalls) { 647 if (IndirCalls.empty()) 648 return; 649 assert(Options.TracePC || Options.TracePCGuard || Options.Inline8bitCounters); 650 for (auto I : IndirCalls) { 651 IRBuilder<> IRB(I); 652 CallSite CS(I); 653 Value *Callee = CS.getCalledValue(); 654 if (isa<InlineAsm>(Callee)) 655 continue; 656 IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy)); 657 } 658 } 659 660 // For every switch statement we insert a call: 661 // __sanitizer_cov_trace_switch(CondValue, 662 // {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... }) 663 664 void SanitizerCoverageModule::InjectTraceForSwitch( 665 Function &, ArrayRef<Instruction *> SwitchTraceTargets) { 666 for (auto I : SwitchTraceTargets) { 667 if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) { 668 IRBuilder<> IRB(I); 669 SmallVector<Constant *, 16> Initializers; 670 Value *Cond = SI->getCondition(); 671 if (Cond->getType()->getScalarSizeInBits() > 672 Int64Ty->getScalarSizeInBits()) 673 continue; 674 Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases())); 675 Initializers.push_back( 676 ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits())); 677 if (Cond->getType()->getScalarSizeInBits() < 678 Int64Ty->getScalarSizeInBits()) 679 Cond = IRB.CreateIntCast(Cond, Int64Ty, false); 680 for (auto It : SI->cases()) { 681 Constant *C = It.getCaseValue(); 682 if (C->getType()->getScalarSizeInBits() < 683 Int64Ty->getScalarSizeInBits()) 684 C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty); 685 Initializers.push_back(C); 686 } 687 llvm::sort(Initializers.begin() + 2, Initializers.end(), 688 [](const Constant *A, const Constant *B) { 689 return cast<ConstantInt>(A)->getLimitedValue() < 690 cast<ConstantInt>(B)->getLimitedValue(); 691 }); 692 ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size()); 693 GlobalVariable *GV = new GlobalVariable( 694 *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage, 695 ConstantArray::get(ArrayOfInt64Ty, Initializers), 696 "__sancov_gen_cov_switch_values"); 697 IRB.CreateCall(SanCovTraceSwitchFunction, 698 {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)}); 699 } 700 } 701 } 702 703 void SanitizerCoverageModule::InjectTraceForDiv( 704 Function &, ArrayRef<BinaryOperator *> DivTraceTargets) { 705 for (auto BO : DivTraceTargets) { 706 IRBuilder<> IRB(BO); 707 Value *A1 = BO->getOperand(1); 708 if (isa<ConstantInt>(A1)) continue; 709 if (!A1->getType()->isIntegerTy()) 710 continue; 711 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType()); 712 int CallbackIdx = TypeSize == 32 ? 0 : 713 TypeSize == 64 ? 1 : -1; 714 if (CallbackIdx < 0) continue; 715 auto Ty = Type::getIntNTy(*C, TypeSize); 716 IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx], 717 {IRB.CreateIntCast(A1, Ty, true)}); 718 } 719 } 720 721 void SanitizerCoverageModule::InjectTraceForGep( 722 Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) { 723 for (auto GEP : GepTraceTargets) { 724 IRBuilder<> IRB(GEP); 725 for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I) 726 if (!isa<ConstantInt>(*I) && (*I)->getType()->isIntegerTy()) 727 IRB.CreateCall(SanCovTraceGepFunction, 728 {IRB.CreateIntCast(*I, IntptrTy, true)}); 729 } 730 } 731 732 void SanitizerCoverageModule::InjectTraceForCmp( 733 Function &, ArrayRef<Instruction *> CmpTraceTargets) { 734 for (auto I : CmpTraceTargets) { 735 if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) { 736 IRBuilder<> IRB(ICMP); 737 Value *A0 = ICMP->getOperand(0); 738 Value *A1 = ICMP->getOperand(1); 739 if (!A0->getType()->isIntegerTy()) 740 continue; 741 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType()); 742 int CallbackIdx = TypeSize == 8 ? 0 : 743 TypeSize == 16 ? 1 : 744 TypeSize == 32 ? 2 : 745 TypeSize == 64 ? 3 : -1; 746 if (CallbackIdx < 0) continue; 747 // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1); 748 auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx]; 749 bool FirstIsConst = isa<ConstantInt>(A0); 750 bool SecondIsConst = isa<ConstantInt>(A1); 751 // If both are const, then we don't need such a comparison. 752 if (FirstIsConst && SecondIsConst) continue; 753 // If only one is const, then make it the first callback argument. 754 if (FirstIsConst || SecondIsConst) { 755 CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx]; 756 if (SecondIsConst) 757 std::swap(A0, A1); 758 } 759 760 auto Ty = Type::getIntNTy(*C, TypeSize); 761 IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true), 762 IRB.CreateIntCast(A1, Ty, true)}); 763 } 764 } 765 } 766 767 void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB, 768 size_t Idx, 769 bool IsLeafFunc) { 770 BasicBlock::iterator IP = BB.getFirstInsertionPt(); 771 bool IsEntryBB = &BB == &F.getEntryBlock(); 772 DebugLoc EntryLoc; 773 if (IsEntryBB) { 774 if (auto SP = F.getSubprogram()) 775 EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP); 776 // Keep static allocas and llvm.localescape calls in the entry block. Even 777 // if we aren't splitting the block, it's nice for allocas to be before 778 // calls. 779 IP = PrepareToSplitEntryBlock(BB, IP); 780 } else { 781 EntryLoc = IP->getDebugLoc(); 782 } 783 784 IRBuilder<> IRB(&*IP); 785 IRB.SetCurrentDebugLocation(EntryLoc); 786 if (Options.TracePC) { 787 IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC. 788 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge. 789 } 790 if (Options.TracePCGuard) { 791 auto GuardPtr = IRB.CreateIntToPtr( 792 IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy), 793 ConstantInt::get(IntptrTy, Idx * 4)), 794 Int32PtrTy); 795 IRB.CreateCall(SanCovTracePCGuard, GuardPtr); 796 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge. 797 } 798 if (Options.Inline8bitCounters) { 799 auto CounterPtr = IRB.CreateGEP( 800 Function8bitCounterArray, 801 {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)}); 802 auto Load = IRB.CreateLoad(CounterPtr); 803 auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1)); 804 auto Store = IRB.CreateStore(Inc, CounterPtr); 805 SetNoSanitizeMetadata(Load); 806 SetNoSanitizeMetadata(Store); 807 } 808 if (Options.StackDepth && IsEntryBB && !IsLeafFunc) { 809 // Check stack depth. If it's the deepest so far, record it. 810 Function *GetFrameAddr = 811 Intrinsic::getDeclaration(F.getParent(), Intrinsic::frameaddress); 812 auto FrameAddrPtr = 813 IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)}); 814 auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy); 815 auto LowestStack = IRB.CreateLoad(SanCovLowestStack); 816 auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack); 817 auto ThenTerm = SplitBlockAndInsertIfThen(IsStackLower, &*IP, false); 818 IRBuilder<> ThenIRB(ThenTerm); 819 auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack); 820 SetNoSanitizeMetadata(LowestStack); 821 SetNoSanitizeMetadata(Store); 822 } 823 } 824 825 std::string 826 SanitizerCoverageModule::getSectionName(const std::string &Section) const { 827 if (TargetTriple.isOSBinFormatCOFF()) { 828 if (Section == SanCovCountersSectionName) 829 return ".SCOV$CM"; 830 if (Section == SanCovPCsSectionName) 831 return ".SCOVP$M"; 832 return ".SCOV$GM"; // For SanCovGuardsSectionName. 833 } 834 if (TargetTriple.isOSBinFormatMachO()) 835 return "__DATA,__" + Section; 836 return "__" + Section; 837 } 838 839 std::string 840 SanitizerCoverageModule::getSectionStart(const std::string &Section) const { 841 if (TargetTriple.isOSBinFormatMachO()) 842 return "\1section$start$__DATA$__" + Section; 843 return "__start___" + Section; 844 } 845 846 std::string 847 SanitizerCoverageModule::getSectionEnd(const std::string &Section) const { 848 if (TargetTriple.isOSBinFormatMachO()) 849 return "\1section$end$__DATA$__" + Section; 850 return "__stop___" + Section; 851 } 852 853 854 char SanitizerCoverageModule::ID = 0; 855 INITIALIZE_PASS_BEGIN(SanitizerCoverageModule, "sancov", 856 "SanitizerCoverage: TODO." 857 "ModulePass", 858 false, false) 859 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) 860 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass) 861 INITIALIZE_PASS_END(SanitizerCoverageModule, "sancov", 862 "SanitizerCoverage: TODO." 863 "ModulePass", 864 false, false) 865 ModulePass *llvm::createSanitizerCoverageModulePass( 866 const SanitizerCoverageOptions &Options) { 867 return new SanitizerCoverageModule(Options); 868 } 869