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