1 //===-- SanitizerCoverage.cpp - coverage instrumentation for sanitizers ---===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // Coverage instrumentation done on LLVM IR level, works with Sanitizers. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "llvm/ADT/ArrayRef.h" 14 #include "llvm/ADT/SmallVector.h" 15 #include "llvm/Analysis/EHPersonalities.h" 16 #include "llvm/Analysis/PostDominators.h" 17 #include "llvm/IR/CFG.h" 18 #include "llvm/IR/CallSite.h" 19 #include "llvm/IR/Constant.h" 20 #include "llvm/IR/DataLayout.h" 21 #include "llvm/IR/DebugInfo.h" 22 #include "llvm/IR/Dominators.h" 23 #include "llvm/IR/Function.h" 24 #include "llvm/IR/GlobalVariable.h" 25 #include "llvm/IR/IRBuilder.h" 26 #include "llvm/IR/InlineAsm.h" 27 #include "llvm/IR/IntrinsicInst.h" 28 #include "llvm/IR/Intrinsics.h" 29 #include "llvm/IR/LLVMContext.h" 30 #include "llvm/IR/MDBuilder.h" 31 #include "llvm/IR/Mangler.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<Value *, Value *> CreateSecStartEnd(Module &M, const char *Section, 215 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 std::string CurModuleUniqueId; 238 Triple TargetTriple; 239 LLVMContext *C; 240 const DataLayout *DL; 241 242 GlobalVariable *FunctionGuardArray; // for trace-pc-guard. 243 GlobalVariable *Function8bitCounterArray; // for inline-8bit-counters. 244 GlobalVariable *FunctionPCsArray; // for pc-table. 245 SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed; 246 SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed; 247 248 SanitizerCoverageOptions Options; 249 }; 250 251 } // namespace 252 253 std::pair<Value *, Value *> 254 SanitizerCoverageModule::CreateSecStartEnd(Module &M, const char *Section, 255 Type *Ty) { 256 GlobalVariable *SecStart = 257 new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage, nullptr, 258 getSectionStart(Section)); 259 SecStart->setVisibility(GlobalValue::HiddenVisibility); 260 GlobalVariable *SecEnd = 261 new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage, 262 nullptr, getSectionEnd(Section)); 263 SecEnd->setVisibility(GlobalValue::HiddenVisibility); 264 IRBuilder<> IRB(M.getContext()); 265 Value *SecEndPtr = IRB.CreatePointerCast(SecEnd, Ty); 266 if (!TargetTriple.isOSBinFormatCOFF()) 267 return std::make_pair(IRB.CreatePointerCast(SecStart, Ty), SecEndPtr); 268 269 // Account for the fact that on windows-msvc __start_* symbols actually 270 // point to a uint64_t before the start of the array. 271 auto SecStartI8Ptr = IRB.CreatePointerCast(SecStart, Int8PtrTy); 272 auto GEP = IRB.CreateGEP(SecStartI8Ptr, 273 ConstantInt::get(IntptrTy, sizeof(uint64_t))); 274 return std::make_pair(IRB.CreatePointerCast(GEP, Ty), SecEndPtr); 275 } 276 277 Function *SanitizerCoverageModule::CreateInitCallsForSections( 278 Module &M, const char *InitFunctionName, Type *Ty, 279 const char *Section) { 280 auto SecStartEnd = CreateSecStartEnd(M, Section, Ty); 281 auto SecStart = SecStartEnd.first; 282 auto SecEnd = SecStartEnd.second; 283 Function *CtorFunc; 284 std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions( 285 M, SanCovModuleCtorName, InitFunctionName, {Ty, Ty}, {SecStart, SecEnd}); 286 287 if (TargetTriple.supportsCOMDAT()) { 288 // Use comdat to dedup CtorFunc. 289 CtorFunc->setComdat(M.getOrInsertComdat(SanCovModuleCtorName)); 290 appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc); 291 } else { 292 appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority); 293 } 294 295 if (TargetTriple.isOSBinFormatCOFF()) { 296 // In COFF files, if the contructors are set as COMDAT (they are because 297 // COFF supports COMDAT) and the linker flag /OPT:REF (strip unreferenced 298 // functions and data) is used, the constructors get stripped. To prevent 299 // this, give the constructors weak ODR linkage and ensure the linker knows 300 // to include the sancov constructor. This way the linker can deduplicate 301 // the constructors but always leave one copy. 302 CtorFunc->setLinkage(GlobalValue::WeakODRLinkage); 303 appendToUsed(M, CtorFunc); 304 } 305 return CtorFunc; 306 } 307 308 bool SanitizerCoverageModule::runOnModule(Module &M) { 309 if (Options.CoverageType == SanitizerCoverageOptions::SCK_None) 310 return false; 311 C = &(M.getContext()); 312 DL = &M.getDataLayout(); 313 CurModule = &M; 314 CurModuleUniqueId = getUniqueModuleId(CurModule); 315 TargetTriple = Triple(M.getTargetTriple()); 316 FunctionGuardArray = nullptr; 317 Function8bitCounterArray = nullptr; 318 FunctionPCsArray = nullptr; 319 IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits()); 320 IntptrPtrTy = PointerType::getUnqual(IntptrTy); 321 Type *VoidTy = Type::getVoidTy(*C); 322 IRBuilder<> IRB(*C); 323 Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty()); 324 Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty()); 325 Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty()); 326 Int64Ty = IRB.getInt64Ty(); 327 Int32Ty = IRB.getInt32Ty(); 328 Int16Ty = IRB.getInt16Ty(); 329 Int8Ty = IRB.getInt8Ty(); 330 331 SanCovTracePCIndir = checkSanitizerInterfaceFunction( 332 M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy)); 333 SanCovTraceCmpFunction[0] = 334 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 335 SanCovTraceCmp1, VoidTy, IRB.getInt8Ty(), IRB.getInt8Ty())); 336 SanCovTraceCmpFunction[1] = checkSanitizerInterfaceFunction( 337 M.getOrInsertFunction(SanCovTraceCmp2, VoidTy, IRB.getInt16Ty(), 338 IRB.getInt16Ty())); 339 SanCovTraceCmpFunction[2] = checkSanitizerInterfaceFunction( 340 M.getOrInsertFunction(SanCovTraceCmp4, VoidTy, IRB.getInt32Ty(), 341 IRB.getInt32Ty())); 342 SanCovTraceCmpFunction[3] = 343 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 344 SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty)); 345 346 SanCovTraceConstCmpFunction[0] = 347 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 348 SanCovTraceConstCmp1, VoidTy, Int8Ty, Int8Ty)); 349 SanCovTraceConstCmpFunction[1] = 350 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 351 SanCovTraceConstCmp2, VoidTy, Int16Ty, Int16Ty)); 352 SanCovTraceConstCmpFunction[2] = 353 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 354 SanCovTraceConstCmp4, VoidTy, Int32Ty, Int32Ty)); 355 SanCovTraceConstCmpFunction[3] = 356 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 357 SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty)); 358 359 SanCovTraceDivFunction[0] = 360 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 361 SanCovTraceDiv4, VoidTy, IRB.getInt32Ty())); 362 SanCovTraceDivFunction[1] = 363 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 364 SanCovTraceDiv8, VoidTy, Int64Ty)); 365 SanCovTraceGepFunction = 366 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 367 SanCovTraceGep, VoidTy, IntptrTy)); 368 SanCovTraceSwitchFunction = 369 checkSanitizerInterfaceFunction(M.getOrInsertFunction( 370 SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy)); 371 372 Constant *SanCovLowestStackConstant = 373 M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy); 374 SanCovLowestStack = cast<GlobalVariable>(SanCovLowestStackConstant); 375 SanCovLowestStack->setThreadLocalMode( 376 GlobalValue::ThreadLocalMode::InitialExecTLSModel); 377 if (Options.StackDepth && !SanCovLowestStack->isDeclaration()) 378 SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy)); 379 380 // Make sure smaller parameters are zero-extended to i64 as required by the 381 // x86_64 ABI. 382 if (TargetTriple.getArch() == Triple::x86_64) { 383 for (int i = 0; i < 3; i++) { 384 SanCovTraceCmpFunction[i]->addParamAttr(0, Attribute::ZExt); 385 SanCovTraceCmpFunction[i]->addParamAttr(1, Attribute::ZExt); 386 SanCovTraceConstCmpFunction[i]->addParamAttr(0, Attribute::ZExt); 387 SanCovTraceConstCmpFunction[i]->addParamAttr(1, Attribute::ZExt); 388 } 389 SanCovTraceDivFunction[0]->addParamAttr(0, Attribute::ZExt); 390 } 391 392 393 // We insert an empty inline asm after cov callbacks to avoid callback merge. 394 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false), 395 StringRef(""), StringRef(""), 396 /*hasSideEffects=*/true); 397 398 SanCovTracePC = checkSanitizerInterfaceFunction( 399 M.getOrInsertFunction(SanCovTracePCName, VoidTy)); 400 SanCovTracePCGuard = checkSanitizerInterfaceFunction(M.getOrInsertFunction( 401 SanCovTracePCGuardName, VoidTy, Int32PtrTy)); 402 403 for (auto &F : M) 404 runOnFunction(F); 405 406 Function *Ctor = nullptr; 407 408 if (FunctionGuardArray) 409 Ctor = CreateInitCallsForSections(M, SanCovTracePCGuardInitName, Int32PtrTy, 410 SanCovGuardsSectionName); 411 if (Function8bitCounterArray) 412 Ctor = CreateInitCallsForSections(M, SanCov8bitCountersInitName, Int8PtrTy, 413 SanCovCountersSectionName); 414 if (Ctor && Options.PCTable) { 415 auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrPtrTy); 416 Function *InitFunction = declareSanitizerInitFunction( 417 M, SanCovPCsInitName, {IntptrPtrTy, IntptrPtrTy}); 418 IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator()); 419 IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second}); 420 } 421 // We don't reference these arrays directly in any of our runtime functions, 422 // so we need to prevent them from being dead stripped. 423 if (TargetTriple.isOSBinFormatMachO()) 424 appendToUsed(M, GlobalsToAppendToUsed); 425 appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed); 426 return true; 427 } 428 429 // True if block has successors and it dominates all of them. 430 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) { 431 if (succ_begin(BB) == succ_end(BB)) 432 return false; 433 434 for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) { 435 if (!DT->dominates(BB, SUCC)) 436 return false; 437 } 438 439 return true; 440 } 441 442 // True if block has predecessors and it postdominates all of them. 443 static bool isFullPostDominator(const BasicBlock *BB, 444 const PostDominatorTree *PDT) { 445 if (pred_begin(BB) == pred_end(BB)) 446 return false; 447 448 for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) { 449 if (!PDT->dominates(BB, PRED)) 450 return false; 451 } 452 453 return true; 454 } 455 456 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB, 457 const DominatorTree *DT, 458 const PostDominatorTree *PDT, 459 const SanitizerCoverageOptions &Options) { 460 // Don't insert coverage for unreachable blocks: we will never call 461 // __sanitizer_cov() for them, so counting them in 462 // NumberOfInstrumentedBlocks() might complicate calculation of code coverage 463 // percentage. Also, unreachable instructions frequently have no debug 464 // locations. 465 if (isa<UnreachableInst>(BB->getTerminator())) 466 return false; 467 468 // Don't insert coverage into blocks without a valid insertion point 469 // (catchswitch blocks). 470 if (BB->getFirstInsertionPt() == BB->end()) 471 return false; 472 473 if (Options.NoPrune || &F.getEntryBlock() == BB) 474 return true; 475 476 if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function && 477 &F.getEntryBlock() != BB) 478 return false; 479 480 // Do not instrument full dominators, or full post-dominators with multiple 481 // predecessors. 482 return !isFullDominator(BB, DT) 483 && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor()); 484 } 485 486 bool SanitizerCoverageModule::runOnFunction(Function &F) { 487 if (F.empty()) 488 return false; 489 if (F.getName().find(".module_ctor") != std::string::npos) 490 return false; // Should not instrument sanitizer init functions. 491 if (F.getName().startswith("__sanitizer_")) 492 return false; // Don't instrument __sanitizer_* callbacks. 493 // Don't touch available_externally functions, their actual body is elewhere. 494 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) 495 return false; 496 // Don't instrument MSVC CRT configuration helpers. They may run before normal 497 // initialization. 498 if (F.getName() == "__local_stdio_printf_options" || 499 F.getName() == "__local_stdio_scanf_options") 500 return false; 501 if (isa<UnreachableInst>(F.getEntryBlock().getTerminator())) 502 return false; 503 // Don't instrument functions using SEH for now. Splitting basic blocks like 504 // we do for coverage breaks WinEHPrepare. 505 // FIXME: Remove this when SEH no longer uses landingpad pattern matching. 506 if (F.hasPersonalityFn() && 507 isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn()))) 508 return false; 509 if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge) 510 SplitAllCriticalEdges(F); 511 SmallVector<Instruction *, 8> IndirCalls; 512 SmallVector<BasicBlock *, 16> BlocksToInstrument; 513 SmallVector<Instruction *, 8> CmpTraceTargets; 514 SmallVector<Instruction *, 8> SwitchTraceTargets; 515 SmallVector<BinaryOperator *, 8> DivTraceTargets; 516 SmallVector<GetElementPtrInst *, 8> GepTraceTargets; 517 518 const DominatorTree *DT = 519 &getAnalysis<DominatorTreeWrapperPass>(F).getDomTree(); 520 const PostDominatorTree *PDT = 521 &getAnalysis<PostDominatorTreeWrapperPass>(F).getPostDomTree(); 522 bool IsLeafFunc = true; 523 524 for (auto &BB : F) { 525 if (shouldInstrumentBlock(F, &BB, DT, PDT, Options)) 526 BlocksToInstrument.push_back(&BB); 527 for (auto &Inst : BB) { 528 if (Options.IndirectCalls) { 529 CallSite CS(&Inst); 530 if (CS && !CS.getCalledFunction()) 531 IndirCalls.push_back(&Inst); 532 } 533 if (Options.TraceCmp) { 534 if (isa<ICmpInst>(&Inst)) 535 CmpTraceTargets.push_back(&Inst); 536 if (isa<SwitchInst>(&Inst)) 537 SwitchTraceTargets.push_back(&Inst); 538 } 539 if (Options.TraceDiv) 540 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst)) 541 if (BO->getOpcode() == Instruction::SDiv || 542 BO->getOpcode() == Instruction::UDiv) 543 DivTraceTargets.push_back(BO); 544 if (Options.TraceGep) 545 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst)) 546 GepTraceTargets.push_back(GEP); 547 if (Options.StackDepth) 548 if (isa<InvokeInst>(Inst) || 549 (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst))) 550 IsLeafFunc = false; 551 } 552 } 553 554 InjectCoverage(F, BlocksToInstrument, IsLeafFunc); 555 InjectCoverageForIndirectCalls(F, IndirCalls); 556 InjectTraceForCmp(F, CmpTraceTargets); 557 InjectTraceForSwitch(F, SwitchTraceTargets); 558 InjectTraceForDiv(F, DivTraceTargets); 559 InjectTraceForGep(F, GepTraceTargets); 560 return true; 561 } 562 563 GlobalVariable *SanitizerCoverageModule::CreateFunctionLocalArrayInSection( 564 size_t NumElements, Function &F, Type *Ty, const char *Section) { 565 ArrayType *ArrayTy = ArrayType::get(Ty, NumElements); 566 auto Array = new GlobalVariable( 567 *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage, 568 Constant::getNullValue(ArrayTy), "__sancov_gen_"); 569 570 if (TargetTriple.supportsCOMDAT() && !F.isInterposable()) 571 if (auto Comdat = 572 GetOrCreateFunctionComdat(F, TargetTriple, CurModuleUniqueId)) 573 Array->setComdat(Comdat); 574 Array->setSection(getSectionName(Section)); 575 Array->setAlignment(Ty->isPointerTy() ? DL->getPointerSize() 576 : Ty->getPrimitiveSizeInBits() / 8); 577 GlobalsToAppendToUsed.push_back(Array); 578 GlobalsToAppendToCompilerUsed.push_back(Array); 579 MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F)); 580 Array->addMetadata(LLVMContext::MD_associated, *MD); 581 582 return Array; 583 } 584 585 GlobalVariable * 586 SanitizerCoverageModule::CreatePCArray(Function &F, 587 ArrayRef<BasicBlock *> AllBlocks) { 588 size_t N = AllBlocks.size(); 589 assert(N); 590 SmallVector<Constant *, 32> PCs; 591 IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt()); 592 for (size_t i = 0; i < N; i++) { 593 if (&F.getEntryBlock() == AllBlocks[i]) { 594 PCs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy)); 595 PCs.push_back((Constant *)IRB.CreateIntToPtr( 596 ConstantInt::get(IntptrTy, 1), IntptrPtrTy)); 597 } else { 598 PCs.push_back((Constant *)IRB.CreatePointerCast( 599 BlockAddress::get(AllBlocks[i]), IntptrPtrTy)); 600 PCs.push_back((Constant *)IRB.CreateIntToPtr( 601 ConstantInt::get(IntptrTy, 0), IntptrPtrTy)); 602 } 603 } 604 auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, IntptrPtrTy, 605 SanCovPCsSectionName); 606 PCArray->setInitializer( 607 ConstantArray::get(ArrayType::get(IntptrPtrTy, N * 2), PCs)); 608 PCArray->setConstant(true); 609 610 return PCArray; 611 } 612 613 void SanitizerCoverageModule::CreateFunctionLocalArrays( 614 Function &F, ArrayRef<BasicBlock *> AllBlocks) { 615 if (Options.TracePCGuard) 616 FunctionGuardArray = CreateFunctionLocalArrayInSection( 617 AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName); 618 619 if (Options.Inline8bitCounters) 620 Function8bitCounterArray = CreateFunctionLocalArrayInSection( 621 AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName); 622 623 if (Options.PCTable) 624 FunctionPCsArray = CreatePCArray(F, AllBlocks); 625 } 626 627 bool SanitizerCoverageModule::InjectCoverage(Function &F, 628 ArrayRef<BasicBlock *> AllBlocks, 629 bool IsLeafFunc) { 630 if (AllBlocks.empty()) return false; 631 CreateFunctionLocalArrays(F, AllBlocks); 632 for (size_t i = 0, N = AllBlocks.size(); i < N; i++) 633 InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc); 634 return true; 635 } 636 637 // On every indirect call we call a run-time function 638 // __sanitizer_cov_indir_call* with two parameters: 639 // - callee address, 640 // - global cache array that contains CacheSize pointers (zero-initialized). 641 // The cache is used to speed up recording the caller-callee pairs. 642 // The address of the caller is passed implicitly via caller PC. 643 // CacheSize is encoded in the name of the run-time function. 644 void SanitizerCoverageModule::InjectCoverageForIndirectCalls( 645 Function &F, ArrayRef<Instruction *> IndirCalls) { 646 if (IndirCalls.empty()) 647 return; 648 assert(Options.TracePC || Options.TracePCGuard || Options.Inline8bitCounters); 649 for (auto I : IndirCalls) { 650 IRBuilder<> IRB(I); 651 CallSite CS(I); 652 Value *Callee = CS.getCalledValue(); 653 if (isa<InlineAsm>(Callee)) 654 continue; 655 IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy)); 656 } 657 } 658 659 // For every switch statement we insert a call: 660 // __sanitizer_cov_trace_switch(CondValue, 661 // {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... }) 662 663 void SanitizerCoverageModule::InjectTraceForSwitch( 664 Function &, ArrayRef<Instruction *> SwitchTraceTargets) { 665 for (auto I : SwitchTraceTargets) { 666 if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) { 667 IRBuilder<> IRB(I); 668 SmallVector<Constant *, 16> Initializers; 669 Value *Cond = SI->getCondition(); 670 if (Cond->getType()->getScalarSizeInBits() > 671 Int64Ty->getScalarSizeInBits()) 672 continue; 673 Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases())); 674 Initializers.push_back( 675 ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits())); 676 if (Cond->getType()->getScalarSizeInBits() < 677 Int64Ty->getScalarSizeInBits()) 678 Cond = IRB.CreateIntCast(Cond, Int64Ty, false); 679 for (auto It : SI->cases()) { 680 Constant *C = It.getCaseValue(); 681 if (C->getType()->getScalarSizeInBits() < 682 Int64Ty->getScalarSizeInBits()) 683 C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty); 684 Initializers.push_back(C); 685 } 686 llvm::sort(Initializers.begin() + 2, Initializers.end(), 687 [](const Constant *A, const Constant *B) { 688 return cast<ConstantInt>(A)->getLimitedValue() < 689 cast<ConstantInt>(B)->getLimitedValue(); 690 }); 691 ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size()); 692 GlobalVariable *GV = new GlobalVariable( 693 *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage, 694 ConstantArray::get(ArrayOfInt64Ty, Initializers), 695 "__sancov_gen_cov_switch_values"); 696 IRB.CreateCall(SanCovTraceSwitchFunction, 697 {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)}); 698 } 699 } 700 } 701 702 void SanitizerCoverageModule::InjectTraceForDiv( 703 Function &, ArrayRef<BinaryOperator *> DivTraceTargets) { 704 for (auto BO : DivTraceTargets) { 705 IRBuilder<> IRB(BO); 706 Value *A1 = BO->getOperand(1); 707 if (isa<ConstantInt>(A1)) continue; 708 if (!A1->getType()->isIntegerTy()) 709 continue; 710 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType()); 711 int CallbackIdx = TypeSize == 32 ? 0 : 712 TypeSize == 64 ? 1 : -1; 713 if (CallbackIdx < 0) continue; 714 auto Ty = Type::getIntNTy(*C, TypeSize); 715 IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx], 716 {IRB.CreateIntCast(A1, Ty, true)}); 717 } 718 } 719 720 void SanitizerCoverageModule::InjectTraceForGep( 721 Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) { 722 for (auto GEP : GepTraceTargets) { 723 IRBuilder<> IRB(GEP); 724 for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I) 725 if (!isa<ConstantInt>(*I) && (*I)->getType()->isIntegerTy()) 726 IRB.CreateCall(SanCovTraceGepFunction, 727 {IRB.CreateIntCast(*I, IntptrTy, true)}); 728 } 729 } 730 731 void SanitizerCoverageModule::InjectTraceForCmp( 732 Function &, ArrayRef<Instruction *> CmpTraceTargets) { 733 for (auto I : CmpTraceTargets) { 734 if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) { 735 IRBuilder<> IRB(ICMP); 736 Value *A0 = ICMP->getOperand(0); 737 Value *A1 = ICMP->getOperand(1); 738 if (!A0->getType()->isIntegerTy()) 739 continue; 740 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType()); 741 int CallbackIdx = TypeSize == 8 ? 0 : 742 TypeSize == 16 ? 1 : 743 TypeSize == 32 ? 2 : 744 TypeSize == 64 ? 3 : -1; 745 if (CallbackIdx < 0) continue; 746 // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1); 747 auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx]; 748 bool FirstIsConst = isa<ConstantInt>(A0); 749 bool SecondIsConst = isa<ConstantInt>(A1); 750 // If both are const, then we don't need such a comparison. 751 if (FirstIsConst && SecondIsConst) continue; 752 // If only one is const, then make it the first callback argument. 753 if (FirstIsConst || SecondIsConst) { 754 CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx]; 755 if (SecondIsConst) 756 std::swap(A0, A1); 757 } 758 759 auto Ty = Type::getIntNTy(*C, TypeSize); 760 IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true), 761 IRB.CreateIntCast(A1, Ty, true)}); 762 } 763 } 764 } 765 766 void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB, 767 size_t Idx, 768 bool IsLeafFunc) { 769 BasicBlock::iterator IP = BB.getFirstInsertionPt(); 770 bool IsEntryBB = &BB == &F.getEntryBlock(); 771 DebugLoc EntryLoc; 772 if (IsEntryBB) { 773 if (auto SP = F.getSubprogram()) 774 EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP); 775 // Keep static allocas and llvm.localescape calls in the entry block. Even 776 // if we aren't splitting the block, it's nice for allocas to be before 777 // calls. 778 IP = PrepareToSplitEntryBlock(BB, IP); 779 } else { 780 EntryLoc = IP->getDebugLoc(); 781 } 782 783 IRBuilder<> IRB(&*IP); 784 IRB.SetCurrentDebugLocation(EntryLoc); 785 if (Options.TracePC) { 786 IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC. 787 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge. 788 } 789 if (Options.TracePCGuard) { 790 auto GuardPtr = IRB.CreateIntToPtr( 791 IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy), 792 ConstantInt::get(IntptrTy, Idx * 4)), 793 Int32PtrTy); 794 IRB.CreateCall(SanCovTracePCGuard, GuardPtr); 795 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge. 796 } 797 if (Options.Inline8bitCounters) { 798 auto CounterPtr = IRB.CreateGEP( 799 Function8bitCounterArray, 800 {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)}); 801 auto Load = IRB.CreateLoad(CounterPtr); 802 auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1)); 803 auto Store = IRB.CreateStore(Inc, CounterPtr); 804 SetNoSanitizeMetadata(Load); 805 SetNoSanitizeMetadata(Store); 806 } 807 if (Options.StackDepth && IsEntryBB && !IsLeafFunc) { 808 // Check stack depth. If it's the deepest so far, record it. 809 Function *GetFrameAddr = 810 Intrinsic::getDeclaration(F.getParent(), Intrinsic::frameaddress); 811 auto FrameAddrPtr = 812 IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)}); 813 auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy); 814 auto LowestStack = IRB.CreateLoad(SanCovLowestStack); 815 auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack); 816 auto ThenTerm = SplitBlockAndInsertIfThen(IsStackLower, &*IP, false); 817 IRBuilder<> ThenIRB(ThenTerm); 818 auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack); 819 SetNoSanitizeMetadata(LowestStack); 820 SetNoSanitizeMetadata(Store); 821 } 822 } 823 824 std::string 825 SanitizerCoverageModule::getSectionName(const std::string &Section) const { 826 if (TargetTriple.isOSBinFormatCOFF()) { 827 if (Section == SanCovCountersSectionName) 828 return ".SCOV$CM"; 829 if (Section == SanCovPCsSectionName) 830 return ".SCOVP$M"; 831 return ".SCOV$GM"; // For SanCovGuardsSectionName. 832 } 833 if (TargetTriple.isOSBinFormatMachO()) 834 return "__DATA,__" + Section; 835 return "__" + Section; 836 } 837 838 std::string 839 SanitizerCoverageModule::getSectionStart(const std::string &Section) const { 840 if (TargetTriple.isOSBinFormatMachO()) 841 return "\1section$start$__DATA$__" + Section; 842 return "__start___" + Section; 843 } 844 845 std::string 846 SanitizerCoverageModule::getSectionEnd(const std::string &Section) const { 847 if (TargetTriple.isOSBinFormatMachO()) 848 return "\1section$end$__DATA$__" + Section; 849 return "__stop___" + Section; 850 } 851 852 853 char SanitizerCoverageModule::ID = 0; 854 INITIALIZE_PASS_BEGIN(SanitizerCoverageModule, "sancov", 855 "SanitizerCoverage: TODO." 856 "ModulePass", 857 false, false) 858 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) 859 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass) 860 INITIALIZE_PASS_END(SanitizerCoverageModule, "sancov", 861 "SanitizerCoverage: TODO." 862 "ModulePass", 863 false, false) 864 ModulePass *llvm::createSanitizerCoverageModulePass( 865 const SanitizerCoverageOptions &Options) { 866 return new SanitizerCoverageModule(Options); 867 } 868