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