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