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<GlobalVariable *, GlobalVariable *> 216 CreateSecStartEnd(Module &M, const char *Section, Type *Ty); 217 218 void SetNoSanitizeMetadata(Instruction *I) { 219 I->setMetadata(I->getModule()->getMDKindID("nosanitize"), 220 MDNode::get(*C, None)); 221 } 222 223 Comdat *GetOrCreateFunctionComdat(Function &F); 224 225 std::string getSectionName(const std::string &Section) const; 226 std::string getSectionStart(const std::string &Section) const; 227 std::string getSectionEnd(const std::string &Section) const; 228 Function *SanCovTracePCIndir; 229 Function *SanCovTracePC, *SanCovTracePCGuard; 230 Function *SanCovTraceCmpFunction[4]; 231 Function *SanCovTraceConstCmpFunction[4]; 232 Function *SanCovTraceDivFunction[2]; 233 Function *SanCovTraceGepFunction; 234 Function *SanCovTraceSwitchFunction; 235 GlobalVariable *SanCovLowestStack; 236 InlineAsm *EmptyAsm; 237 Type *IntptrTy, *IntptrPtrTy, *Int64Ty, *Int64PtrTy, *Int32Ty, *Int32PtrTy, 238 *Int16Ty, *Int8Ty, *Int8PtrTy; 239 Module *CurModule; 240 std::string CurModuleUniqueId; 241 Triple TargetTriple; 242 LLVMContext *C; 243 const DataLayout *DL; 244 245 GlobalVariable *FunctionGuardArray; // for trace-pc-guard. 246 GlobalVariable *Function8bitCounterArray; // for inline-8bit-counters. 247 GlobalVariable *FunctionPCsArray; // for pc-table. 248 SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed; 249 SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed; 250 251 SanitizerCoverageOptions Options; 252 }; 253 254 } // namespace 255 256 std::pair<GlobalVariable *, GlobalVariable *> 257 SanitizerCoverageModule::CreateSecStartEnd(Module &M, const char *Section, 258 Type *Ty) { 259 GlobalVariable *SecStart = 260 new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage, nullptr, 261 getSectionStart(Section)); 262 SecStart->setVisibility(GlobalValue::HiddenVisibility); 263 GlobalVariable *SecEnd = 264 new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage, 265 nullptr, getSectionEnd(Section)); 266 SecEnd->setVisibility(GlobalValue::HiddenVisibility); 267 268 return std::make_pair(SecStart, SecEnd); 269 } 270 271 272 Function *SanitizerCoverageModule::CreateInitCallsForSections( 273 Module &M, const char *InitFunctionName, Type *Ty, 274 const char *Section) { 275 IRBuilder<> IRB(M.getContext()); 276 auto SecStartEnd = CreateSecStartEnd(M, Section, Ty); 277 auto SecStart = SecStartEnd.first; 278 auto SecEnd = SecStartEnd.second; 279 Function *CtorFunc; 280 Value *SecStartPtr = nullptr; 281 // Account for the fact that on windows-msvc __start_* symbols actually 282 // point to a uint64_t before the start of the array. 283 if (TargetTriple.getObjectFormat() == Triple::COFF) { 284 auto SecStartI8Ptr = IRB.CreatePointerCast(SecStart, Int8PtrTy); 285 auto GEP = IRB.CreateGEP(SecStartI8Ptr, 286 ConstantInt::get(IntptrTy, sizeof(uint64_t))); 287 SecStartPtr = IRB.CreatePointerCast(GEP, Ty); 288 } else { 289 SecStartPtr = IRB.CreatePointerCast(SecStart, Ty); 290 } 291 std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions( 292 M, SanCovModuleCtorName, InitFunctionName, {Ty, Ty}, 293 {SecStartPtr, IRB.CreatePointerCast(SecEnd, Ty)}); 294 295 if (TargetTriple.supportsCOMDAT()) { 296 // Use comdat to dedup CtorFunc. 297 CtorFunc->setComdat(M.getOrInsertComdat(SanCovModuleCtorName)); 298 appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc); 299 } else { 300 appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority); 301 } 302 303 if (TargetTriple.getObjectFormat() == Triple::COFF) { 304 // In COFF files, if the contructors are set as COMDAT (they are because 305 // COFF supports COMDAT) and the linker flag /OPT:REF (strip unreferenced 306 // functions and data) is used, the constructors get stripped. To prevent 307 // this, give the constructors weak ODR linkage and tell the linker to 308 // always include the sancov constructor. This way the linker can 309 // deduplicate the constructors but always leave one copy. 310 CtorFunc->setLinkage(GlobalValue::WeakODRLinkage); 311 SmallString<20> PartialIncDirective("/include:"); 312 // Get constructor's mangled name in order to support i386. 313 SmallString<40> MangledName; 314 Mangler().getNameWithPrefix(MangledName, CtorFunc, true); 315 Twine IncDirective = PartialIncDirective + MangledName; 316 Metadata *Args[1] = {MDString::get(*C, IncDirective.str())}; 317 MDNode *MetadataNode = MDNode::get(*C, Args); 318 NamedMDNode *NamedMetadata = 319 M.getOrInsertNamedMetadata("llvm.linker.options"); 320 NamedMetadata->addOperand(MetadataNode); 321 } 322 return CtorFunc; 323 } 324 325 bool SanitizerCoverageModule::runOnModule(Module &M) { 326 if (Options.CoverageType == SanitizerCoverageOptions::SCK_None) 327 return false; 328 C = &(M.getContext()); 329 DL = &M.getDataLayout(); 330 CurModule = &M; 331 CurModuleUniqueId = getUniqueModuleId(CurModule); 332 TargetTriple = Triple(M.getTargetTriple()); 333 FunctionGuardArray = nullptr; 334 Function8bitCounterArray = nullptr; 335 FunctionPCsArray = nullptr; 336 IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits()); 337 IntptrPtrTy = PointerType::getUnqual(IntptrTy); 338 Type *VoidTy = Type::getVoidTy(*C); 339 IRBuilder<> IRB(*C); 340 Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty()); 341 Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty()); 342 Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty()); 343 Int64Ty = IRB.getInt64Ty(); 344 Int32Ty = IRB.getInt32Ty(); 345 Int16Ty = IRB.getInt16Ty(); 346 Int8Ty = IRB.getInt8Ty(); 347 348 SanCovTracePCIndir = checkSanitizerInterfaceFunction( 349 M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy)); 350 SanCovTraceCmpFunction[0] = 351 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 352 SanCovTraceCmp1, VoidTy, IRB.getInt8Ty(), IRB.getInt8Ty())); 353 SanCovTraceCmpFunction[1] = checkSanitizerInterfaceFunction( 354 M.getOrInsertFunction(SanCovTraceCmp2, VoidTy, IRB.getInt16Ty(), 355 IRB.getInt16Ty())); 356 SanCovTraceCmpFunction[2] = checkSanitizerInterfaceFunction( 357 M.getOrInsertFunction(SanCovTraceCmp4, VoidTy, IRB.getInt32Ty(), 358 IRB.getInt32Ty())); 359 SanCovTraceCmpFunction[3] = 360 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 361 SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty)); 362 363 SanCovTraceConstCmpFunction[0] = 364 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 365 SanCovTraceConstCmp1, VoidTy, Int8Ty, Int8Ty)); 366 SanCovTraceConstCmpFunction[1] = 367 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 368 SanCovTraceConstCmp2, VoidTy, Int16Ty, Int16Ty)); 369 SanCovTraceConstCmpFunction[2] = 370 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 371 SanCovTraceConstCmp4, VoidTy, Int32Ty, Int32Ty)); 372 SanCovTraceConstCmpFunction[3] = 373 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 374 SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty)); 375 376 SanCovTraceDivFunction[0] = 377 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 378 SanCovTraceDiv4, VoidTy, IRB.getInt32Ty())); 379 SanCovTraceDivFunction[1] = 380 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 381 SanCovTraceDiv8, VoidTy, Int64Ty)); 382 SanCovTraceGepFunction = 383 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 384 SanCovTraceGep, VoidTy, IntptrTy)); 385 SanCovTraceSwitchFunction = 386 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 387 SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy)); 388 389 Constant *SanCovLowestStackConstant = 390 M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy); 391 SanCovLowestStack = cast<GlobalVariable>(SanCovLowestStackConstant); 392 SanCovLowestStack->setThreadLocalMode( 393 GlobalValue::ThreadLocalMode::InitialExecTLSModel); 394 if (Options.StackDepth && !SanCovLowestStack->isDeclaration()) 395 SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy)); 396 397 // Make sure smaller parameters are zero-extended to i64 as required by the 398 // x86_64 ABI. 399 if (TargetTriple.getArch() == Triple::x86_64) { 400 for (int i = 0; i < 3; i++) { 401 SanCovTraceCmpFunction[i]->addParamAttr(0, Attribute::ZExt); 402 SanCovTraceCmpFunction[i]->addParamAttr(1, Attribute::ZExt); 403 SanCovTraceConstCmpFunction[i]->addParamAttr(0, Attribute::ZExt); 404 SanCovTraceConstCmpFunction[i]->addParamAttr(1, Attribute::ZExt); 405 } 406 SanCovTraceDivFunction[0]->addParamAttr(0, Attribute::ZExt); 407 } 408 409 410 // We insert an empty inline asm after cov callbacks to avoid callback merge. 411 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false), 412 StringRef(""), StringRef(""), 413 /*hasSideEffects=*/true); 414 415 SanCovTracePC = checkSanitizerInterfaceFunction( 416 M.getOrInsertFunction(SanCovTracePCName, VoidTy)); 417 SanCovTracePCGuard = checkSanitizerInterfaceFunction(M.getOrInsertFunction( 418 SanCovTracePCGuardName, VoidTy, Int32PtrTy)); 419 420 for (auto &F : M) 421 runOnFunction(F); 422 423 Function *Ctor = nullptr; 424 425 if (FunctionGuardArray) 426 Ctor = CreateInitCallsForSections(M, SanCovTracePCGuardInitName, Int32PtrTy, 427 SanCovGuardsSectionName); 428 if (Function8bitCounterArray) 429 Ctor = CreateInitCallsForSections(M, SanCov8bitCountersInitName, Int8PtrTy, 430 SanCovCountersSectionName); 431 if (Ctor && Options.PCTable) { 432 auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrPtrTy); 433 Function *InitFunction = declareSanitizerInitFunction( 434 M, SanCovPCsInitName, {IntptrPtrTy, IntptrPtrTy}); 435 IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator()); 436 Value *SecStartPtr = nullptr; 437 // Account for the fact that on windows-msvc __start_pc_table actually 438 // points to a uint64_t before the start of the PC table. 439 if (TargetTriple.getObjectFormat() == Triple::COFF) { 440 auto SecStartI8Ptr = IRB.CreatePointerCast(SecStartEnd.first, Int8PtrTy); 441 auto GEP = IRB.CreateGEP(SecStartI8Ptr, 442 ConstantInt::get(IntptrTy, sizeof(uint64_t))); 443 SecStartPtr = IRB.CreatePointerCast(GEP, IntptrPtrTy); 444 } else { 445 SecStartPtr = IRB.CreatePointerCast(SecStartEnd.first, IntptrPtrTy); 446 } 447 IRBCtor.CreateCall( 448 InitFunction, 449 {SecStartPtr, IRB.CreatePointerCast(SecStartEnd.second, IntptrPtrTy)}); 450 } 451 // We don't reference these arrays directly in any of our runtime functions, 452 // so we need to prevent them from being dead stripped. 453 if (TargetTriple.isOSBinFormatMachO()) 454 appendToUsed(M, GlobalsToAppendToUsed); 455 appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed); 456 return true; 457 } 458 459 // True if block has successors and it dominates all of them. 460 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) { 461 if (succ_begin(BB) == succ_end(BB)) 462 return false; 463 464 for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) { 465 if (!DT->dominates(BB, SUCC)) 466 return false; 467 } 468 469 return true; 470 } 471 472 // True if block has predecessors and it postdominates all of them. 473 static bool isFullPostDominator(const BasicBlock *BB, 474 const PostDominatorTree *PDT) { 475 if (pred_begin(BB) == pred_end(BB)) 476 return false; 477 478 for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) { 479 if (!PDT->dominates(BB, PRED)) 480 return false; 481 } 482 483 return true; 484 } 485 486 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB, 487 const DominatorTree *DT, 488 const PostDominatorTree *PDT, 489 const SanitizerCoverageOptions &Options) { 490 // Don't insert coverage for unreachable blocks: we will never call 491 // __sanitizer_cov() for them, so counting them in 492 // NumberOfInstrumentedBlocks() might complicate calculation of code coverage 493 // percentage. Also, unreachable instructions frequently have no debug 494 // locations. 495 if (isa<UnreachableInst>(BB->getTerminator())) 496 return false; 497 498 // Don't insert coverage into blocks without a valid insertion point 499 // (catchswitch blocks). 500 if (BB->getFirstInsertionPt() == BB->end()) 501 return false; 502 503 if (Options.NoPrune || &F.getEntryBlock() == BB) 504 return true; 505 506 if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function && 507 &F.getEntryBlock() != BB) 508 return false; 509 510 // Do not instrument full dominators, or full post-dominators with multiple 511 // predecessors. 512 return !isFullDominator(BB, DT) 513 && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor()); 514 } 515 516 bool SanitizerCoverageModule::runOnFunction(Function &F) { 517 if (F.empty()) 518 return false; 519 if (F.getName().find(".module_ctor") != std::string::npos) 520 return false; // Should not instrument sanitizer init functions. 521 if (F.getName().startswith("__sanitizer_")) 522 return false; // Don't instrument __sanitizer_* callbacks. 523 // Don't touch available_externally functions, their actual body is elewhere. 524 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) 525 return false; 526 // Don't instrument MSVC CRT configuration helpers. They may run before normal 527 // initialization. 528 if (F.getName() == "__local_stdio_printf_options" || 529 F.getName() == "__local_stdio_scanf_options") 530 return false; 531 if (isa<UnreachableInst>(F.getEntryBlock().getTerminator())) 532 return false; 533 // Don't instrument functions using SEH for now. Splitting basic blocks like 534 // we do for coverage breaks WinEHPrepare. 535 // FIXME: Remove this when SEH no longer uses landingpad pattern matching. 536 if (F.hasPersonalityFn() && 537 isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn()))) 538 return false; 539 if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge) 540 SplitAllCriticalEdges(F); 541 SmallVector<Instruction *, 8> IndirCalls; 542 SmallVector<BasicBlock *, 16> BlocksToInstrument; 543 SmallVector<Instruction *, 8> CmpTraceTargets; 544 SmallVector<Instruction *, 8> SwitchTraceTargets; 545 SmallVector<BinaryOperator *, 8> DivTraceTargets; 546 SmallVector<GetElementPtrInst *, 8> GepTraceTargets; 547 548 const DominatorTree *DT = 549 &getAnalysis<DominatorTreeWrapperPass>(F).getDomTree(); 550 const PostDominatorTree *PDT = 551 &getAnalysis<PostDominatorTreeWrapperPass>(F).getPostDomTree(); 552 bool IsLeafFunc = true; 553 554 for (auto &BB : F) { 555 if (shouldInstrumentBlock(F, &BB, DT, PDT, Options)) 556 BlocksToInstrument.push_back(&BB); 557 for (auto &Inst : BB) { 558 if (Options.IndirectCalls) { 559 CallSite CS(&Inst); 560 if (CS && !CS.getCalledFunction()) 561 IndirCalls.push_back(&Inst); 562 } 563 if (Options.TraceCmp) { 564 if (isa<ICmpInst>(&Inst)) 565 CmpTraceTargets.push_back(&Inst); 566 if (isa<SwitchInst>(&Inst)) 567 SwitchTraceTargets.push_back(&Inst); 568 } 569 if (Options.TraceDiv) 570 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst)) 571 if (BO->getOpcode() == Instruction::SDiv || 572 BO->getOpcode() == Instruction::UDiv) 573 DivTraceTargets.push_back(BO); 574 if (Options.TraceGep) 575 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst)) 576 GepTraceTargets.push_back(GEP); 577 if (Options.StackDepth) 578 if (isa<InvokeInst>(Inst) || 579 (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst))) 580 IsLeafFunc = false; 581 } 582 } 583 584 InjectCoverage(F, BlocksToInstrument, IsLeafFunc); 585 InjectCoverageForIndirectCalls(F, IndirCalls); 586 InjectTraceForCmp(F, CmpTraceTargets); 587 InjectTraceForSwitch(F, SwitchTraceTargets); 588 InjectTraceForDiv(F, DivTraceTargets); 589 InjectTraceForGep(F, GepTraceTargets); 590 return true; 591 } 592 593 Comdat *SanitizerCoverageModule::GetOrCreateFunctionComdat(Function &F) { 594 if (auto Comdat = F.getComdat()) return Comdat; 595 if (!TargetTriple.isOSBinFormatELF()) return nullptr; 596 assert(F.hasName()); 597 std::string Name = F.getName(); 598 if (F.hasLocalLinkage()) { 599 if (CurModuleUniqueId.empty()) return nullptr; 600 Name += CurModuleUniqueId; 601 } 602 auto Comdat = CurModule->getOrInsertComdat(Name); 603 F.setComdat(Comdat); 604 return Comdat; 605 } 606 607 GlobalVariable *SanitizerCoverageModule::CreateFunctionLocalArrayInSection( 608 size_t NumElements, Function &F, Type *Ty, const char *Section) { 609 ArrayType *ArrayTy = ArrayType::get(Ty, NumElements); 610 auto Array = new GlobalVariable( 611 *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage, 612 Constant::getNullValue(ArrayTy), "__sancov_gen_"); 613 if (auto Comdat = GetOrCreateFunctionComdat(F)) 614 Array->setComdat(Comdat); 615 Array->setSection(getSectionName(Section)); 616 Array->setAlignment(Ty->isPointerTy() ? DL->getPointerSize() 617 : Ty->getPrimitiveSizeInBits() / 8); 618 GlobalsToAppendToUsed.push_back(Array); 619 GlobalsToAppendToCompilerUsed.push_back(Array); 620 MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F)); 621 Array->addMetadata(LLVMContext::MD_associated, *MD); 622 623 return Array; 624 } 625 626 GlobalVariable * 627 SanitizerCoverageModule::CreatePCArray(Function &F, 628 ArrayRef<BasicBlock *> AllBlocks) { 629 size_t N = AllBlocks.size(); 630 assert(N); 631 SmallVector<Constant *, 32> PCs; 632 IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt()); 633 for (size_t i = 0; i < N; i++) { 634 if (&F.getEntryBlock() == AllBlocks[i]) { 635 PCs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy)); 636 PCs.push_back((Constant *)IRB.CreateIntToPtr( 637 ConstantInt::get(IntptrTy, 1), IntptrPtrTy)); 638 } else { 639 PCs.push_back((Constant *)IRB.CreatePointerCast( 640 BlockAddress::get(AllBlocks[i]), IntptrPtrTy)); 641 PCs.push_back((Constant *)IRB.CreateIntToPtr( 642 ConstantInt::get(IntptrTy, 0), IntptrPtrTy)); 643 } 644 } 645 auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, IntptrPtrTy, 646 SanCovPCsSectionName); 647 PCArray->setInitializer( 648 ConstantArray::get(ArrayType::get(IntptrPtrTy, N * 2), PCs)); 649 PCArray->setConstant(true); 650 651 return PCArray; 652 } 653 654 void SanitizerCoverageModule::CreateFunctionLocalArrays( 655 Function &F, ArrayRef<BasicBlock *> AllBlocks) { 656 if (Options.TracePCGuard) 657 FunctionGuardArray = CreateFunctionLocalArrayInSection( 658 AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName); 659 660 if (Options.Inline8bitCounters) 661 Function8bitCounterArray = CreateFunctionLocalArrayInSection( 662 AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName); 663 664 if (Options.PCTable) 665 FunctionPCsArray = CreatePCArray(F, AllBlocks); 666 } 667 668 bool SanitizerCoverageModule::InjectCoverage(Function &F, 669 ArrayRef<BasicBlock *> AllBlocks, 670 bool IsLeafFunc) { 671 if (AllBlocks.empty()) return false; 672 CreateFunctionLocalArrays(F, AllBlocks); 673 for (size_t i = 0, N = AllBlocks.size(); i < N; i++) 674 InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc); 675 return true; 676 } 677 678 // On every indirect call we call a run-time function 679 // __sanitizer_cov_indir_call* with two parameters: 680 // - callee address, 681 // - global cache array that contains CacheSize pointers (zero-initialized). 682 // The cache is used to speed up recording the caller-callee pairs. 683 // The address of the caller is passed implicitly via caller PC. 684 // CacheSize is encoded in the name of the run-time function. 685 void SanitizerCoverageModule::InjectCoverageForIndirectCalls( 686 Function &F, ArrayRef<Instruction *> IndirCalls) { 687 if (IndirCalls.empty()) 688 return; 689 assert(Options.TracePC || Options.TracePCGuard || Options.Inline8bitCounters); 690 for (auto I : IndirCalls) { 691 IRBuilder<> IRB(I); 692 CallSite CS(I); 693 Value *Callee = CS.getCalledValue(); 694 if (isa<InlineAsm>(Callee)) 695 continue; 696 IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy)); 697 } 698 } 699 700 // For every switch statement we insert a call: 701 // __sanitizer_cov_trace_switch(CondValue, 702 // {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... }) 703 704 void SanitizerCoverageModule::InjectTraceForSwitch( 705 Function &, ArrayRef<Instruction *> SwitchTraceTargets) { 706 for (auto I : SwitchTraceTargets) { 707 if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) { 708 IRBuilder<> IRB(I); 709 SmallVector<Constant *, 16> Initializers; 710 Value *Cond = SI->getCondition(); 711 if (Cond->getType()->getScalarSizeInBits() > 712 Int64Ty->getScalarSizeInBits()) 713 continue; 714 Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases())); 715 Initializers.push_back( 716 ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits())); 717 if (Cond->getType()->getScalarSizeInBits() < 718 Int64Ty->getScalarSizeInBits()) 719 Cond = IRB.CreateIntCast(Cond, Int64Ty, false); 720 for (auto It : SI->cases()) { 721 Constant *C = It.getCaseValue(); 722 if (C->getType()->getScalarSizeInBits() < 723 Int64Ty->getScalarSizeInBits()) 724 C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty); 725 Initializers.push_back(C); 726 } 727 llvm::sort(Initializers.begin() + 2, Initializers.end(), 728 [](const Constant *A, const Constant *B) { 729 return cast<ConstantInt>(A)->getLimitedValue() < 730 cast<ConstantInt>(B)->getLimitedValue(); 731 }); 732 ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size()); 733 GlobalVariable *GV = new GlobalVariable( 734 *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage, 735 ConstantArray::get(ArrayOfInt64Ty, Initializers), 736 "__sancov_gen_cov_switch_values"); 737 IRB.CreateCall(SanCovTraceSwitchFunction, 738 {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)}); 739 } 740 } 741 } 742 743 void SanitizerCoverageModule::InjectTraceForDiv( 744 Function &, ArrayRef<BinaryOperator *> DivTraceTargets) { 745 for (auto BO : DivTraceTargets) { 746 IRBuilder<> IRB(BO); 747 Value *A1 = BO->getOperand(1); 748 if (isa<ConstantInt>(A1)) continue; 749 if (!A1->getType()->isIntegerTy()) 750 continue; 751 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType()); 752 int CallbackIdx = TypeSize == 32 ? 0 : 753 TypeSize == 64 ? 1 : -1; 754 if (CallbackIdx < 0) continue; 755 auto Ty = Type::getIntNTy(*C, TypeSize); 756 IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx], 757 {IRB.CreateIntCast(A1, Ty, true)}); 758 } 759 } 760 761 void SanitizerCoverageModule::InjectTraceForGep( 762 Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) { 763 for (auto GEP : GepTraceTargets) { 764 IRBuilder<> IRB(GEP); 765 for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I) 766 if (!isa<ConstantInt>(*I) && (*I)->getType()->isIntegerTy()) 767 IRB.CreateCall(SanCovTraceGepFunction, 768 {IRB.CreateIntCast(*I, IntptrTy, true)}); 769 } 770 } 771 772 void SanitizerCoverageModule::InjectTraceForCmp( 773 Function &, ArrayRef<Instruction *> CmpTraceTargets) { 774 for (auto I : CmpTraceTargets) { 775 if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) { 776 IRBuilder<> IRB(ICMP); 777 Value *A0 = ICMP->getOperand(0); 778 Value *A1 = ICMP->getOperand(1); 779 if (!A0->getType()->isIntegerTy()) 780 continue; 781 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType()); 782 int CallbackIdx = TypeSize == 8 ? 0 : 783 TypeSize == 16 ? 1 : 784 TypeSize == 32 ? 2 : 785 TypeSize == 64 ? 3 : -1; 786 if (CallbackIdx < 0) continue; 787 // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1); 788 auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx]; 789 bool FirstIsConst = isa<ConstantInt>(A0); 790 bool SecondIsConst = isa<ConstantInt>(A1); 791 // If both are const, then we don't need such a comparison. 792 if (FirstIsConst && SecondIsConst) continue; 793 // If only one is const, then make it the first callback argument. 794 if (FirstIsConst || SecondIsConst) { 795 CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx]; 796 if (SecondIsConst) 797 std::swap(A0, A1); 798 } 799 800 auto Ty = Type::getIntNTy(*C, TypeSize); 801 IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true), 802 IRB.CreateIntCast(A1, Ty, true)}); 803 } 804 } 805 } 806 807 void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB, 808 size_t Idx, 809 bool IsLeafFunc) { 810 BasicBlock::iterator IP = BB.getFirstInsertionPt(); 811 bool IsEntryBB = &BB == &F.getEntryBlock(); 812 DebugLoc EntryLoc; 813 if (IsEntryBB) { 814 if (auto SP = F.getSubprogram()) 815 EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP); 816 // Keep static allocas and llvm.localescape calls in the entry block. Even 817 // if we aren't splitting the block, it's nice for allocas to be before 818 // calls. 819 IP = PrepareToSplitEntryBlock(BB, IP); 820 } else { 821 EntryLoc = IP->getDebugLoc(); 822 } 823 824 IRBuilder<> IRB(&*IP); 825 IRB.SetCurrentDebugLocation(EntryLoc); 826 if (Options.TracePC) { 827 IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC. 828 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge. 829 } 830 if (Options.TracePCGuard) { 831 auto GuardPtr = IRB.CreateIntToPtr( 832 IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy), 833 ConstantInt::get(IntptrTy, Idx * 4)), 834 Int32PtrTy); 835 IRB.CreateCall(SanCovTracePCGuard, GuardPtr); 836 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge. 837 } 838 if (Options.Inline8bitCounters) { 839 auto CounterPtr = IRB.CreateGEP( 840 Function8bitCounterArray, 841 {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)}); 842 auto Load = IRB.CreateLoad(CounterPtr); 843 auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1)); 844 auto Store = IRB.CreateStore(Inc, CounterPtr); 845 SetNoSanitizeMetadata(Load); 846 SetNoSanitizeMetadata(Store); 847 } 848 if (Options.StackDepth && IsEntryBB && !IsLeafFunc) { 849 // Check stack depth. If it's the deepest so far, record it. 850 Function *GetFrameAddr = 851 Intrinsic::getDeclaration(F.getParent(), Intrinsic::frameaddress); 852 auto FrameAddrPtr = 853 IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)}); 854 auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy); 855 auto LowestStack = IRB.CreateLoad(SanCovLowestStack); 856 auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack); 857 auto ThenTerm = SplitBlockAndInsertIfThen(IsStackLower, &*IP, false); 858 IRBuilder<> ThenIRB(ThenTerm); 859 auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack); 860 SetNoSanitizeMetadata(LowestStack); 861 SetNoSanitizeMetadata(Store); 862 } 863 } 864 865 std::string 866 SanitizerCoverageModule::getSectionName(const std::string &Section) const { 867 if (TargetTriple.getObjectFormat() == Triple::COFF) { 868 if (Section == SanCovCountersSectionName) 869 return ".SCOV$CM"; 870 if (Section == SanCovPCsSectionName) 871 return ".SCOVP$M"; 872 return ".SCOV$GM"; // For SanCovGuardsSectionName. 873 } 874 if (TargetTriple.isOSBinFormatMachO()) 875 return "__DATA,__" + Section; 876 return "__" + Section; 877 } 878 879 std::string 880 SanitizerCoverageModule::getSectionStart(const std::string &Section) const { 881 if (TargetTriple.isOSBinFormatMachO()) 882 return "\1section$start$__DATA$__" + Section; 883 return "__start___" + Section; 884 } 885 886 std::string 887 SanitizerCoverageModule::getSectionEnd(const std::string &Section) const { 888 if (TargetTriple.isOSBinFormatMachO()) 889 return "\1section$end$__DATA$__" + Section; 890 return "__stop___" + Section; 891 } 892 893 894 char SanitizerCoverageModule::ID = 0; 895 INITIALIZE_PASS_BEGIN(SanitizerCoverageModule, "sancov", 896 "SanitizerCoverage: TODO." 897 "ModulePass", 898 false, false) 899 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) 900 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass) 901 INITIALIZE_PASS_END(SanitizerCoverageModule, "sancov", 902 "SanitizerCoverage: TODO." 903 "ModulePass", 904 false, false) 905 ModulePass *llvm::createSanitizerCoverageModulePass( 906 const SanitizerCoverageOptions &Options) { 907 return new SanitizerCoverageModule(Options); 908 } 909