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 FunctionCallee SanCovTracePCIndir; 226 FunctionCallee SanCovTracePC, SanCovTracePCGuard; 227 FunctionCallee SanCovTraceCmpFunction[4]; 228 FunctionCallee SanCovTraceConstCmpFunction[4]; 229 FunctionCallee SanCovTraceDivFunction[2]; 230 FunctionCallee SanCovTraceGepFunction; 231 FunctionCallee 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(Int8Ty, 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 = 332 M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy); 333 // Make sure smaller parameters are zero-extended to i64 as required by the 334 // x86_64 ABI. 335 AttributeList SanCovTraceCmpZeroExtAL; 336 if (TargetTriple.getArch() == Triple::x86_64) { 337 SanCovTraceCmpZeroExtAL = 338 SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 0, Attribute::ZExt); 339 SanCovTraceCmpZeroExtAL = 340 SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 1, Attribute::ZExt); 341 } 342 343 SanCovTraceCmpFunction[0] = 344 M.getOrInsertFunction(SanCovTraceCmp1, SanCovTraceCmpZeroExtAL, VoidTy, 345 IRB.getInt8Ty(), IRB.getInt8Ty()); 346 SanCovTraceCmpFunction[1] = 347 M.getOrInsertFunction(SanCovTraceCmp2, SanCovTraceCmpZeroExtAL, VoidTy, 348 IRB.getInt16Ty(), IRB.getInt16Ty()); 349 SanCovTraceCmpFunction[2] = 350 M.getOrInsertFunction(SanCovTraceCmp4, SanCovTraceCmpZeroExtAL, VoidTy, 351 IRB.getInt32Ty(), IRB.getInt32Ty()); 352 SanCovTraceCmpFunction[3] = 353 M.getOrInsertFunction(SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty); 354 355 SanCovTraceConstCmpFunction[0] = M.getOrInsertFunction( 356 SanCovTraceConstCmp1, SanCovTraceCmpZeroExtAL, VoidTy, Int8Ty, Int8Ty); 357 SanCovTraceConstCmpFunction[1] = M.getOrInsertFunction( 358 SanCovTraceConstCmp2, SanCovTraceCmpZeroExtAL, VoidTy, Int16Ty, Int16Ty); 359 SanCovTraceConstCmpFunction[2] = M.getOrInsertFunction( 360 SanCovTraceConstCmp4, SanCovTraceCmpZeroExtAL, VoidTy, Int32Ty, Int32Ty); 361 SanCovTraceConstCmpFunction[3] = 362 M.getOrInsertFunction(SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty); 363 364 { 365 AttributeList AL; 366 if (TargetTriple.getArch() == Triple::x86_64) 367 AL = AL.addParamAttribute(*C, 0, Attribute::ZExt); 368 SanCovTraceDivFunction[0] = 369 M.getOrInsertFunction(SanCovTraceDiv4, AL, VoidTy, IRB.getInt32Ty()); 370 } 371 SanCovTraceDivFunction[1] = 372 M.getOrInsertFunction(SanCovTraceDiv8, VoidTy, Int64Ty); 373 SanCovTraceGepFunction = 374 M.getOrInsertFunction(SanCovTraceGep, VoidTy, IntptrTy); 375 SanCovTraceSwitchFunction = 376 M.getOrInsertFunction(SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy); 377 378 Constant *SanCovLowestStackConstant = 379 M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy); 380 SanCovLowestStack = dyn_cast<GlobalVariable>(SanCovLowestStackConstant); 381 if (!SanCovLowestStack) { 382 C->emitError(StringRef("'") + SanCovLowestStackName + 383 "' should not be declared by the user"); 384 return true; 385 } 386 SanCovLowestStack->setThreadLocalMode( 387 GlobalValue::ThreadLocalMode::InitialExecTLSModel); 388 if (Options.StackDepth && !SanCovLowestStack->isDeclaration()) 389 SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy)); 390 391 // We insert an empty inline asm after cov callbacks to avoid callback merge. 392 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false), 393 StringRef(""), StringRef(""), 394 /*hasSideEffects=*/true); 395 396 SanCovTracePC = M.getOrInsertFunction(SanCovTracePCName, VoidTy); 397 SanCovTracePCGuard = 398 M.getOrInsertFunction(SanCovTracePCGuardName, VoidTy, Int32PtrTy); 399 400 for (auto &F : M) 401 runOnFunction(F); 402 403 Function *Ctor = nullptr; 404 405 if (FunctionGuardArray) 406 Ctor = CreateInitCallsForSections(M, SanCovTracePCGuardInitName, Int32PtrTy, 407 SanCovGuardsSectionName); 408 if (Function8bitCounterArray) 409 Ctor = CreateInitCallsForSections(M, SanCov8bitCountersInitName, Int8PtrTy, 410 SanCovCountersSectionName); 411 if (Ctor && Options.PCTable) { 412 auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrPtrTy); 413 FunctionCallee InitFunction = declareSanitizerInitFunction( 414 M, SanCovPCsInitName, {IntptrPtrTy, IntptrPtrTy}); 415 IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator()); 416 IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second}); 417 } 418 // We don't reference these arrays directly in any of our runtime functions, 419 // so we need to prevent them from being dead stripped. 420 if (TargetTriple.isOSBinFormatMachO()) 421 appendToUsed(M, GlobalsToAppendToUsed); 422 appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed); 423 return true; 424 } 425 426 // True if block has successors and it dominates all of them. 427 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) { 428 if (succ_begin(BB) == succ_end(BB)) 429 return false; 430 431 for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) { 432 if (!DT->dominates(BB, SUCC)) 433 return false; 434 } 435 436 return true; 437 } 438 439 // True if block has predecessors and it postdominates all of them. 440 static bool isFullPostDominator(const BasicBlock *BB, 441 const PostDominatorTree *PDT) { 442 if (pred_begin(BB) == pred_end(BB)) 443 return false; 444 445 for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) { 446 if (!PDT->dominates(BB, PRED)) 447 return false; 448 } 449 450 return true; 451 } 452 453 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB, 454 const DominatorTree *DT, 455 const PostDominatorTree *PDT, 456 const SanitizerCoverageOptions &Options) { 457 // Don't insert coverage for blocks containing nothing but unreachable: we 458 // will never call __sanitizer_cov() for them, so counting them in 459 // NumberOfInstrumentedBlocks() might complicate calculation of code coverage 460 // percentage. Also, unreachable instructions frequently have no debug 461 // locations. 462 if (isa<UnreachableInst>(BB->getFirstNonPHIOrDbgOrLifetime())) 463 return false; 464 465 // Don't insert coverage into blocks without a valid insertion point 466 // (catchswitch blocks). 467 if (BB->getFirstInsertionPt() == BB->end()) 468 return false; 469 470 if (Options.NoPrune || &F.getEntryBlock() == BB) 471 return true; 472 473 if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function && 474 &F.getEntryBlock() != BB) 475 return false; 476 477 // Do not instrument full dominators, or full post-dominators with multiple 478 // predecessors. 479 return !isFullDominator(BB, DT) 480 && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor()); 481 } 482 483 484 // Returns true iff From->To is a backedge. 485 // A twist here is that we treat From->To as a backedge if 486 // * To dominates From or 487 // * To->UniqueSuccessor dominates From 488 static bool IsBackEdge(BasicBlock *From, BasicBlock *To, 489 const DominatorTree *DT) { 490 if (DT->dominates(To, From)) 491 return true; 492 if (auto Next = To->getUniqueSuccessor()) 493 if (DT->dominates(Next, From)) 494 return true; 495 return false; 496 } 497 498 // Prunes uninteresting Cmp instrumentation: 499 // * CMP instructions that feed into loop backedge branch. 500 // 501 // Note that Cmp pruning is controlled by the same flag as the 502 // BB pruning. 503 static bool IsInterestingCmp(ICmpInst *CMP, const DominatorTree *DT, 504 const SanitizerCoverageOptions &Options) { 505 if (!Options.NoPrune) 506 if (CMP->hasOneUse()) 507 if (auto BR = dyn_cast<BranchInst>(CMP->user_back())) 508 for (BasicBlock *B : BR->successors()) 509 if (IsBackEdge(BR->getParent(), B, DT)) 510 return false; 511 return true; 512 } 513 514 bool SanitizerCoverageModule::runOnFunction(Function &F) { 515 if (F.empty()) 516 return false; 517 if (F.getName().find(".module_ctor") != std::string::npos) 518 return false; // Should not instrument sanitizer init functions. 519 if (F.getName().startswith("__sanitizer_")) 520 return false; // Don't instrument __sanitizer_* callbacks. 521 // Don't touch available_externally functions, their actual body is elewhere. 522 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) 523 return false; 524 // Don't instrument MSVC CRT configuration helpers. They may run before normal 525 // initialization. 526 if (F.getName() == "__local_stdio_printf_options" || 527 F.getName() == "__local_stdio_scanf_options") 528 return false; 529 if (isa<UnreachableInst>(F.getEntryBlock().getTerminator())) 530 return false; 531 // Don't instrument functions using SEH for now. Splitting basic blocks like 532 // we do for coverage breaks WinEHPrepare. 533 // FIXME: Remove this when SEH no longer uses landingpad pattern matching. 534 if (F.hasPersonalityFn() && 535 isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn()))) 536 return false; 537 if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge) 538 SplitAllCriticalEdges(F); 539 SmallVector<Instruction *, 8> IndirCalls; 540 SmallVector<BasicBlock *, 16> BlocksToInstrument; 541 SmallVector<Instruction *, 8> CmpTraceTargets; 542 SmallVector<Instruction *, 8> SwitchTraceTargets; 543 SmallVector<BinaryOperator *, 8> DivTraceTargets; 544 SmallVector<GetElementPtrInst *, 8> GepTraceTargets; 545 546 const DominatorTree *DT = 547 &getAnalysis<DominatorTreeWrapperPass>(F).getDomTree(); 548 const PostDominatorTree *PDT = 549 &getAnalysis<PostDominatorTreeWrapperPass>(F).getPostDomTree(); 550 bool IsLeafFunc = true; 551 552 for (auto &BB : F) { 553 if (shouldInstrumentBlock(F, &BB, DT, PDT, Options)) 554 BlocksToInstrument.push_back(&BB); 555 for (auto &Inst : BB) { 556 if (Options.IndirectCalls) { 557 CallSite CS(&Inst); 558 if (CS && !CS.getCalledFunction()) 559 IndirCalls.push_back(&Inst); 560 } 561 if (Options.TraceCmp) { 562 if (ICmpInst *CMP = dyn_cast<ICmpInst>(&Inst)) 563 if (IsInterestingCmp(CMP, DT, Options)) 564 CmpTraceTargets.push_back(&Inst); 565 if (isa<SwitchInst>(&Inst)) 566 SwitchTraceTargets.push_back(&Inst); 567 } 568 if (Options.TraceDiv) 569 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst)) 570 if (BO->getOpcode() == Instruction::SDiv || 571 BO->getOpcode() == Instruction::UDiv) 572 DivTraceTargets.push_back(BO); 573 if (Options.TraceGep) 574 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst)) 575 GepTraceTargets.push_back(GEP); 576 if (Options.StackDepth) 577 if (isa<InvokeInst>(Inst) || 578 (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst))) 579 IsLeafFunc = false; 580 } 581 } 582 583 InjectCoverage(F, BlocksToInstrument, IsLeafFunc); 584 InjectCoverageForIndirectCalls(F, IndirCalls); 585 InjectTraceForCmp(F, CmpTraceTargets); 586 InjectTraceForSwitch(F, SwitchTraceTargets); 587 InjectTraceForDiv(F, DivTraceTargets); 588 InjectTraceForGep(F, GepTraceTargets); 589 return true; 590 } 591 592 GlobalVariable *SanitizerCoverageModule::CreateFunctionLocalArrayInSection( 593 size_t NumElements, Function &F, Type *Ty, const char *Section) { 594 ArrayType *ArrayTy = ArrayType::get(Ty, NumElements); 595 auto Array = new GlobalVariable( 596 *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage, 597 Constant::getNullValue(ArrayTy), "__sancov_gen_"); 598 599 if (TargetTriple.supportsCOMDAT() && !F.isInterposable()) 600 if (auto Comdat = 601 GetOrCreateFunctionComdat(F, TargetTriple, CurModuleUniqueId)) 602 Array->setComdat(Comdat); 603 Array->setSection(getSectionName(Section)); 604 Array->setAlignment(Ty->isPointerTy() ? DL->getPointerSize() 605 : Ty->getPrimitiveSizeInBits() / 8); 606 GlobalsToAppendToUsed.push_back(Array); 607 GlobalsToAppendToCompilerUsed.push_back(Array); 608 MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F)); 609 Array->addMetadata(LLVMContext::MD_associated, *MD); 610 611 return Array; 612 } 613 614 GlobalVariable * 615 SanitizerCoverageModule::CreatePCArray(Function &F, 616 ArrayRef<BasicBlock *> AllBlocks) { 617 size_t N = AllBlocks.size(); 618 assert(N); 619 SmallVector<Constant *, 32> PCs; 620 IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt()); 621 for (size_t i = 0; i < N; i++) { 622 if (&F.getEntryBlock() == AllBlocks[i]) { 623 PCs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy)); 624 PCs.push_back((Constant *)IRB.CreateIntToPtr( 625 ConstantInt::get(IntptrTy, 1), IntptrPtrTy)); 626 } else { 627 PCs.push_back((Constant *)IRB.CreatePointerCast( 628 BlockAddress::get(AllBlocks[i]), IntptrPtrTy)); 629 PCs.push_back((Constant *)IRB.CreateIntToPtr( 630 ConstantInt::get(IntptrTy, 0), IntptrPtrTy)); 631 } 632 } 633 auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, IntptrPtrTy, 634 SanCovPCsSectionName); 635 PCArray->setInitializer( 636 ConstantArray::get(ArrayType::get(IntptrPtrTy, N * 2), PCs)); 637 PCArray->setConstant(true); 638 639 return PCArray; 640 } 641 642 void SanitizerCoverageModule::CreateFunctionLocalArrays( 643 Function &F, ArrayRef<BasicBlock *> AllBlocks) { 644 if (Options.TracePCGuard) 645 FunctionGuardArray = CreateFunctionLocalArrayInSection( 646 AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName); 647 648 if (Options.Inline8bitCounters) 649 Function8bitCounterArray = CreateFunctionLocalArrayInSection( 650 AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName); 651 652 if (Options.PCTable) 653 FunctionPCsArray = CreatePCArray(F, AllBlocks); 654 } 655 656 bool SanitizerCoverageModule::InjectCoverage(Function &F, 657 ArrayRef<BasicBlock *> AllBlocks, 658 bool IsLeafFunc) { 659 if (AllBlocks.empty()) return false; 660 CreateFunctionLocalArrays(F, AllBlocks); 661 for (size_t i = 0, N = AllBlocks.size(); i < N; i++) 662 InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc); 663 return true; 664 } 665 666 // On every indirect call we call a run-time function 667 // __sanitizer_cov_indir_call* with two parameters: 668 // - callee address, 669 // - global cache array that contains CacheSize pointers (zero-initialized). 670 // The cache is used to speed up recording the caller-callee pairs. 671 // The address of the caller is passed implicitly via caller PC. 672 // CacheSize is encoded in the name of the run-time function. 673 void SanitizerCoverageModule::InjectCoverageForIndirectCalls( 674 Function &F, ArrayRef<Instruction *> IndirCalls) { 675 if (IndirCalls.empty()) 676 return; 677 assert(Options.TracePC || Options.TracePCGuard || Options.Inline8bitCounters); 678 for (auto I : IndirCalls) { 679 IRBuilder<> IRB(I); 680 CallSite CS(I); 681 Value *Callee = CS.getCalledValue(); 682 if (isa<InlineAsm>(Callee)) 683 continue; 684 IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy)); 685 } 686 } 687 688 // For every switch statement we insert a call: 689 // __sanitizer_cov_trace_switch(CondValue, 690 // {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... }) 691 692 void SanitizerCoverageModule::InjectTraceForSwitch( 693 Function &, ArrayRef<Instruction *> SwitchTraceTargets) { 694 for (auto I : SwitchTraceTargets) { 695 if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) { 696 IRBuilder<> IRB(I); 697 SmallVector<Constant *, 16> Initializers; 698 Value *Cond = SI->getCondition(); 699 if (Cond->getType()->getScalarSizeInBits() > 700 Int64Ty->getScalarSizeInBits()) 701 continue; 702 Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases())); 703 Initializers.push_back( 704 ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits())); 705 if (Cond->getType()->getScalarSizeInBits() < 706 Int64Ty->getScalarSizeInBits()) 707 Cond = IRB.CreateIntCast(Cond, Int64Ty, false); 708 for (auto It : SI->cases()) { 709 Constant *C = It.getCaseValue(); 710 if (C->getType()->getScalarSizeInBits() < 711 Int64Ty->getScalarSizeInBits()) 712 C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty); 713 Initializers.push_back(C); 714 } 715 llvm::sort(Initializers.begin() + 2, Initializers.end(), 716 [](const Constant *A, const Constant *B) { 717 return cast<ConstantInt>(A)->getLimitedValue() < 718 cast<ConstantInt>(B)->getLimitedValue(); 719 }); 720 ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size()); 721 GlobalVariable *GV = new GlobalVariable( 722 *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage, 723 ConstantArray::get(ArrayOfInt64Ty, Initializers), 724 "__sancov_gen_cov_switch_values"); 725 IRB.CreateCall(SanCovTraceSwitchFunction, 726 {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)}); 727 } 728 } 729 } 730 731 void SanitizerCoverageModule::InjectTraceForDiv( 732 Function &, ArrayRef<BinaryOperator *> DivTraceTargets) { 733 for (auto BO : DivTraceTargets) { 734 IRBuilder<> IRB(BO); 735 Value *A1 = BO->getOperand(1); 736 if (isa<ConstantInt>(A1)) continue; 737 if (!A1->getType()->isIntegerTy()) 738 continue; 739 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType()); 740 int CallbackIdx = TypeSize == 32 ? 0 : 741 TypeSize == 64 ? 1 : -1; 742 if (CallbackIdx < 0) continue; 743 auto Ty = Type::getIntNTy(*C, TypeSize); 744 IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx], 745 {IRB.CreateIntCast(A1, Ty, true)}); 746 } 747 } 748 749 void SanitizerCoverageModule::InjectTraceForGep( 750 Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) { 751 for (auto GEP : GepTraceTargets) { 752 IRBuilder<> IRB(GEP); 753 for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I) 754 if (!isa<ConstantInt>(*I) && (*I)->getType()->isIntegerTy()) 755 IRB.CreateCall(SanCovTraceGepFunction, 756 {IRB.CreateIntCast(*I, IntptrTy, true)}); 757 } 758 } 759 760 void SanitizerCoverageModule::InjectTraceForCmp( 761 Function &, ArrayRef<Instruction *> CmpTraceTargets) { 762 for (auto I : CmpTraceTargets) { 763 if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) { 764 IRBuilder<> IRB(ICMP); 765 Value *A0 = ICMP->getOperand(0); 766 Value *A1 = ICMP->getOperand(1); 767 if (!A0->getType()->isIntegerTy()) 768 continue; 769 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType()); 770 int CallbackIdx = TypeSize == 8 ? 0 : 771 TypeSize == 16 ? 1 : 772 TypeSize == 32 ? 2 : 773 TypeSize == 64 ? 3 : -1; 774 if (CallbackIdx < 0) continue; 775 // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1); 776 auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx]; 777 bool FirstIsConst = isa<ConstantInt>(A0); 778 bool SecondIsConst = isa<ConstantInt>(A1); 779 // If both are const, then we don't need such a comparison. 780 if (FirstIsConst && SecondIsConst) continue; 781 // If only one is const, then make it the first callback argument. 782 if (FirstIsConst || SecondIsConst) { 783 CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx]; 784 if (SecondIsConst) 785 std::swap(A0, A1); 786 } 787 788 auto Ty = Type::getIntNTy(*C, TypeSize); 789 IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true), 790 IRB.CreateIntCast(A1, Ty, true)}); 791 } 792 } 793 } 794 795 void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB, 796 size_t Idx, 797 bool IsLeafFunc) { 798 BasicBlock::iterator IP = BB.getFirstInsertionPt(); 799 bool IsEntryBB = &BB == &F.getEntryBlock(); 800 DebugLoc EntryLoc; 801 if (IsEntryBB) { 802 if (auto SP = F.getSubprogram()) 803 EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP); 804 // Keep static allocas and llvm.localescape calls in the entry block. Even 805 // if we aren't splitting the block, it's nice for allocas to be before 806 // calls. 807 IP = PrepareToSplitEntryBlock(BB, IP); 808 } else { 809 EntryLoc = IP->getDebugLoc(); 810 } 811 812 IRBuilder<> IRB(&*IP); 813 IRB.SetCurrentDebugLocation(EntryLoc); 814 if (Options.TracePC) { 815 IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC. 816 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge. 817 } 818 if (Options.TracePCGuard) { 819 auto GuardPtr = IRB.CreateIntToPtr( 820 IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy), 821 ConstantInt::get(IntptrTy, Idx * 4)), 822 Int32PtrTy); 823 IRB.CreateCall(SanCovTracePCGuard, GuardPtr); 824 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge. 825 } 826 if (Options.Inline8bitCounters) { 827 auto CounterPtr = IRB.CreateGEP( 828 Function8bitCounterArray->getValueType(), Function8bitCounterArray, 829 {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)}); 830 auto Load = IRB.CreateLoad(Int8Ty, CounterPtr); 831 auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1)); 832 auto Store = IRB.CreateStore(Inc, CounterPtr); 833 SetNoSanitizeMetadata(Load); 834 SetNoSanitizeMetadata(Store); 835 } 836 if (Options.StackDepth && IsEntryBB && !IsLeafFunc) { 837 // Check stack depth. If it's the deepest so far, record it. 838 Function *GetFrameAddr = 839 Intrinsic::getDeclaration(F.getParent(), Intrinsic::frameaddress); 840 auto FrameAddrPtr = 841 IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)}); 842 auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy); 843 auto LowestStack = IRB.CreateLoad(IntptrTy, SanCovLowestStack); 844 auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack); 845 auto ThenTerm = SplitBlockAndInsertIfThen(IsStackLower, &*IP, false); 846 IRBuilder<> ThenIRB(ThenTerm); 847 auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack); 848 SetNoSanitizeMetadata(LowestStack); 849 SetNoSanitizeMetadata(Store); 850 } 851 } 852 853 std::string 854 SanitizerCoverageModule::getSectionName(const std::string &Section) const { 855 if (TargetTriple.isOSBinFormatCOFF()) { 856 if (Section == SanCovCountersSectionName) 857 return ".SCOV$CM"; 858 if (Section == SanCovPCsSectionName) 859 return ".SCOVP$M"; 860 return ".SCOV$GM"; // For SanCovGuardsSectionName. 861 } 862 if (TargetTriple.isOSBinFormatMachO()) 863 return "__DATA,__" + Section; 864 return "__" + Section; 865 } 866 867 std::string 868 SanitizerCoverageModule::getSectionStart(const std::string &Section) const { 869 if (TargetTriple.isOSBinFormatMachO()) 870 return "\1section$start$__DATA$__" + Section; 871 return "__start___" + Section; 872 } 873 874 std::string 875 SanitizerCoverageModule::getSectionEnd(const std::string &Section) const { 876 if (TargetTriple.isOSBinFormatMachO()) 877 return "\1section$end$__DATA$__" + Section; 878 return "__stop___" + Section; 879 } 880 881 882 char SanitizerCoverageModule::ID = 0; 883 INITIALIZE_PASS_BEGIN(SanitizerCoverageModule, "sancov", 884 "SanitizerCoverage: TODO." 885 "ModulePass", 886 false, false) 887 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) 888 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass) 889 INITIALIZE_PASS_END(SanitizerCoverageModule, "sancov", 890 "SanitizerCoverage: TODO." 891 "ModulePass", 892 false, false) 893 ModulePass *llvm::createSanitizerCoverageModulePass( 894 const SanitizerCoverageOptions &Options) { 895 return new SanitizerCoverageModule(Options); 896 } 897