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