lib/Transforms/Instrumentation/SanitizerCoverage.cpp

   1 //===-- SanitizerCoverage.cpp - coverage instrumentation for sanitizers ---===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // Coverage instrumentation done on LLVM IR level, works with Sanitizers.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/ADT/ArrayRef.h"
  15 #include "llvm/ADT/SmallVector.h"
  16 #include "llvm/Analysis/EHPersonalities.h"
  17 #include "llvm/Analysis/PostDominators.h"
  18 #include "llvm/IR/CFG.h"
  19 #include "llvm/IR/CallSite.h"
  20 #include "llvm/IR/Constant.h"
  21 #include "llvm/IR/DataLayout.h"
  22 #include "llvm/IR/DebugInfo.h"
  23 #include "llvm/IR/Dominators.h"
  24 #include "llvm/IR/Function.h"
  25 #include "llvm/IR/GlobalVariable.h"
  26 #include "llvm/IR/IRBuilder.h"
  27 #include "llvm/IR/InlineAsm.h"
  28 #include "llvm/IR/IntrinsicInst.h"
  29 #include "llvm/IR/Intrinsics.h"
  30 #include "llvm/IR/LLVMContext.h"
  31 #include "llvm/IR/MDBuilder.h"
  32 #include "llvm/IR/Module.h"
  33 #include "llvm/IR/Type.h"
  34 #include "llvm/Support/CommandLine.h"
  35 #include "llvm/Support/Debug.h"
  36 #include "llvm/Support/raw_ostream.h"
  37 #include "llvm/Transforms/Instrumentation.h"
  38 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
  39 #include "llvm/Transforms/Utils/ModuleUtils.h"
  40
  41 using namespace llvm;
  42
  43 #define DEBUG_TYPE "sancov"
  44
  45 static const char *const SanCovTracePCIndirName =
  46     "__sanitizer_cov_trace_pc_indir";
  47 static const char *const SanCovTracePCName = "__sanitizer_cov_trace_pc";
  48 static const char *const SanCovTraceCmp1 = "__sanitizer_cov_trace_cmp1";
  49 static const char *const SanCovTraceCmp2 = "__sanitizer_cov_trace_cmp2";
  50 static const char *const SanCovTraceCmp4 = "__sanitizer_cov_trace_cmp4";
  51 static const char *const SanCovTraceCmp8 = "__sanitizer_cov_trace_cmp8";
  52 static const char *const SanCovTraceConstCmp1 =
  53     "__sanitizer_cov_trace_const_cmp1";
  54 static const char *const SanCovTraceConstCmp2 =
  55     "__sanitizer_cov_trace_const_cmp2";
  56 static const char *const SanCovTraceConstCmp4 =
  57     "__sanitizer_cov_trace_const_cmp4";
  58 static const char *const SanCovTraceConstCmp8 =
  59     "__sanitizer_cov_trace_const_cmp8";
  60 static const char *const SanCovTraceDiv4 = "__sanitizer_cov_trace_div4";
  61 static const char *const SanCovTraceDiv8 = "__sanitizer_cov_trace_div8";
  62 static const char *const SanCovTraceGep = "__sanitizer_cov_trace_gep";
  63 static const char *const SanCovTraceSwitchName = "__sanitizer_cov_trace_switch";
  64 static const char *const SanCovModuleCtorName = "sancov.module_ctor";
  65 static const uint64_t SanCtorAndDtorPriority = 2;
  66
  67 static const char *const SanCovTracePCGuardName =
  68     "__sanitizer_cov_trace_pc_guard";
  69 static const char *const SanCovTracePCGuardInitName =
  70     "__sanitizer_cov_trace_pc_guard_init";
  71 static const char *const SanCov8bitCountersInitName =
  72     "__sanitizer_cov_8bit_counters_init";
  73 static const char *const SanCovPCsInitName = "__sanitizer_cov_pcs_init";
  74
  75 static const char *const SanCovGuardsSectionName = "sancov_guards";
  76 static const char *const SanCovCountersSectionName = "sancov_cntrs";
  77 static const char *const SanCovPCsSectionName = "sancov_pcs";
  78
  79 static const char *const SanCovLowestStackName = "__sancov_lowest_stack";
  80
  81 static cl::opt<int> ClCoverageLevel(
  82     "sanitizer-coverage-level",
  83     cl::desc("Sanitizer Coverage. 0: none, 1: entry block, 2: all blocks, "
  84              "3: all blocks and critical edges"),
  85     cl::Hidden, cl::init(0));
  86
  87 static cl::opt<bool> ClTracePC("sanitizer-coverage-trace-pc",
  88                                cl::desc("Experimental pc tracing"), cl::Hidden,
  89                                cl::init(false));
  90
  91 static cl::opt<bool> ClTracePCGuard("sanitizer-coverage-trace-pc-guard",
  92                                     cl::desc("pc tracing with a guard"),
  93                                     cl::Hidden, cl::init(false));
  94
  95 // If true, we create a global variable that contains PCs of all instrumented
  96 // BBs, put this global into a named section, and pass this section's bounds
  97 // to __sanitizer_cov_pcs_init.
  98 // This way the coverage instrumentation does not need to acquire the PCs
  99 // at run-time. Works with trace-pc-guard and inline-8bit-counters.
 100 static cl::opt<bool> ClCreatePCTable("sanitizer-coverage-pc-table",
 101                                      cl::desc("create a static PC table"),
 102                                      cl::Hidden, cl::init(false));
 103
 104 static cl::opt<bool>
 105     ClInline8bitCounters("sanitizer-coverage-inline-8bit-counters",
 106                          cl::desc("increments 8-bit counter for every edge"),
 107                          cl::Hidden, cl::init(false));
 108
 109 static cl::opt<bool>
 110     ClCMPTracing("sanitizer-coverage-trace-compares",
 111                  cl::desc("Tracing of CMP and similar instructions"),
 112                  cl::Hidden, cl::init(false));
 113
 114 static cl::opt<bool> ClDIVTracing("sanitizer-coverage-trace-divs",
 115                                   cl::desc("Tracing of DIV instructions"),
 116                                   cl::Hidden, cl::init(false));
 117
 118 static cl::opt<bool> ClGEPTracing("sanitizer-coverage-trace-geps",
 119                                   cl::desc("Tracing of GEP instructions"),
 120                                   cl::Hidden, cl::init(false));
 121
 122 static cl::opt<bool>
 123     ClPruneBlocks("sanitizer-coverage-prune-blocks",
 124                   cl::desc("Reduce the number of instrumented blocks"),
 125                   cl::Hidden, cl::init(true));
 126
 127 static cl::opt<bool> ClStackDepth("sanitizer-coverage-stack-depth",
 128                                   cl::desc("max stack depth tracing"),
 129                                   cl::Hidden, cl::init(false));
 130
 131 namespace {
 132
 133 SanitizerCoverageOptions getOptions(int LegacyCoverageLevel) {
 134   SanitizerCoverageOptions Res;
 135   switch (LegacyCoverageLevel) {
 136   case 0:
 137     Res.CoverageType = SanitizerCoverageOptions::SCK_None;
 138     break;
 139   case 1:
 140     Res.CoverageType = SanitizerCoverageOptions::SCK_Function;
 141     break;
 142   case 2:
 143     Res.CoverageType = SanitizerCoverageOptions::SCK_BB;
 144     break;
 145   case 3:
 146     Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
 147     break;
 148   case 4:
 149     Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
 150     Res.IndirectCalls = true;
 151     break;
 152   }
 153   return Res;
 154 }
 155
 156 SanitizerCoverageOptions OverrideFromCL(SanitizerCoverageOptions Options) {
 157   // Sets CoverageType and IndirectCalls.
 158   SanitizerCoverageOptions CLOpts = getOptions(ClCoverageLevel);
 159   Options.CoverageType = std::max(Options.CoverageType, CLOpts.CoverageType);
 160   Options.IndirectCalls |= CLOpts.IndirectCalls;
 161   Options.TraceCmp |= ClCMPTracing;
 162   Options.TraceDiv |= ClDIVTracing;
 163   Options.TraceGep |= ClGEPTracing;
 164   Options.TracePC |= ClTracePC;
 165   Options.TracePCGuard |= ClTracePCGuard;
 166   Options.Inline8bitCounters |= ClInline8bitCounters;
 167   Options.PCTable |= ClCreatePCTable;
 168   Options.NoPrune |= !ClPruneBlocks;
 169   Options.StackDepth |= ClStackDepth;
 170   if (!Options.TracePCGuard && !Options.TracePC &&
 171       !Options.Inline8bitCounters && !Options.StackDepth)
 172     Options.TracePCGuard = true; // TracePCGuard is default.
 173   return Options;
 174 }
 175
 176 class SanitizerCoverageModule : public ModulePass {
 177 public:
 178   SanitizerCoverageModule(
 179       const SanitizerCoverageOptions &Options = SanitizerCoverageOptions())
 180       : ModulePass(ID), Options(OverrideFromCL(Options)) {
 181     initializeSanitizerCoverageModulePass(*PassRegistry::getPassRegistry());
 182   }
 183   bool runOnModule(Module &M) override;
 184   bool runOnFunction(Function &F);
 185   static char ID; // Pass identification, replacement for typeid
 186   StringRef getPassName() const override { return "SanitizerCoverageModule"; }
 187
 188   void getAnalysisUsage(AnalysisUsage &AU) const override {
 189     AU.addRequired<DominatorTreeWrapperPass>();
 190     AU.addRequired<PostDominatorTreeWrapperPass>();
 191   }
 192
 193 private:
 194   void InjectCoverageForIndirectCalls(Function &F,
 195                                       ArrayRef<Instruction *> IndirCalls);
 196   void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
 197   void InjectTraceForDiv(Function &F,
 198                          ArrayRef<BinaryOperator *> DivTraceTargets);
 199   void InjectTraceForGep(Function &F,
 200                          ArrayRef<GetElementPtrInst *> GepTraceTargets);
 201   void InjectTraceForSwitch(Function &F,
 202                             ArrayRef<Instruction *> SwitchTraceTargets);
 203   bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks,
 204                       bool IsLeafFunc = true);
 205   GlobalVariable *CreateFunctionLocalArrayInSection(size_t NumElements,
 206                                                     Function &F, Type *Ty,
 207                                                     const char *Section);
 208   GlobalVariable *CreatePCArray(Function &F, ArrayRef<BasicBlock *> AllBlocks);
 209   void CreateFunctionLocalArrays(Function &F, ArrayRef<BasicBlock *> AllBlocks);
 210   void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx,
 211                              bool IsLeafFunc = true);
 212   Function *CreateInitCallsForSections(Module &M, const char *InitFunctionName,
 213                                        Type *Ty, const char *Section);
 214   std::pair<GlobalVariable *, GlobalVariable *>
 215   CreateSecStartEnd(Module &M, const char *Section, Type *Ty);
 216
 217   void SetNoSanitizeMetadata(Instruction *I) {
 218     I->setMetadata(I->getModule()->getMDKindID("nosanitize"),
 219                    MDNode::get(*C, None));
 220   }
 221
 222   Comdat *GetOrCreateFunctionComdat(Function &F);
 223
 224   std::string getSectionName(const std::string &Section) const;
 225   std::string getSectionStart(const std::string &Section) const;
 226   std::string getSectionEnd(const std::string &Section) const;
 227   Function *SanCovTracePCIndir;
 228   Function *SanCovTracePC, *SanCovTracePCGuard;
 229   Function *SanCovTraceCmpFunction[4];
 230   Function *SanCovTraceConstCmpFunction[4];
 231   Function *SanCovTraceDivFunction[2];
 232   Function *SanCovTraceGepFunction;
 233   Function *SanCovTraceSwitchFunction;
 234   GlobalVariable *SanCovLowestStack;
 235   InlineAsm *EmptyAsm;
 236   Type *IntptrTy, *IntptrPtrTy, *Int64Ty, *Int64PtrTy, *Int32Ty, *Int32PtrTy,
 237       *Int16Ty, *Int8Ty, *Int8PtrTy;
 238   Module *CurModule;
 239   std::string CurModuleUniqueId;
 240   Triple TargetTriple;
 241   LLVMContext *C;
 242   const DataLayout *DL;
 243
 244   GlobalVariable *FunctionGuardArray;  // for trace-pc-guard.
 245   GlobalVariable *Function8bitCounterArray;  // for inline-8bit-counters.
 246   GlobalVariable *FunctionPCsArray;  // for pc-table.
 247   SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed;
 248   SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed;
 249
 250   SanitizerCoverageOptions Options;
 251 };
 252
 253 } // namespace
 254
 255 std::pair<GlobalVariable *, GlobalVariable *>
 256 SanitizerCoverageModule::CreateSecStartEnd(Module &M, const char *Section,
 257                                            Type *Ty) {
 258   GlobalVariable *SecStart =
 259       new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage, nullptr,
 260                          getSectionStart(Section));
 261   SecStart->setVisibility(GlobalValue::HiddenVisibility);
 262   GlobalVariable *SecEnd =
 263       new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage,
 264                          nullptr, getSectionEnd(Section));
 265   SecEnd->setVisibility(GlobalValue::HiddenVisibility);
 266
 267   return std::make_pair(SecStart, SecEnd);
 268 }
 269
 270
 271 Function *SanitizerCoverageModule::CreateInitCallsForSections(
 272     Module &M, const char *InitFunctionName, Type *Ty,
 273     const char *Section) {
 274   IRBuilder<> IRB(M.getContext());
 275   auto SecStartEnd = CreateSecStartEnd(M, Section, Ty);
 276   auto SecStart = SecStartEnd.first;
 277   auto SecEnd = SecStartEnd.second;
 278   Function *CtorFunc;
 279   Value *SecStartPtr = nullptr;
 280   // Account for the fact that on windows-msvc __start_* symbols actually
 281   // point to a uint64_t before the start of the array.
 282   if (TargetTriple.getObjectFormat() == Triple::COFF) {
 283     auto SecStartI8Ptr = IRB.CreatePointerCast(SecStart, Int8PtrTy);
 284     auto GEP = IRB.CreateGEP(SecStartI8Ptr,
 285                              ConstantInt::get(IntptrTy, sizeof(uint64_t)));
 286     SecStartPtr = IRB.CreatePointerCast(GEP, Ty);
 287   } else {
 288     SecStartPtr = IRB.CreatePointerCast(SecStart, Ty);
 289   }
 290   std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
 291       M, SanCovModuleCtorName, InitFunctionName, {Ty, Ty},
 292       {SecStartPtr, IRB.CreatePointerCast(SecEnd, Ty)});
 293
 294   if (TargetTriple.supportsCOMDAT()) {
 295     // Use comdat to dedup CtorFunc.
 296     CtorFunc->setComdat(M.getOrInsertComdat(SanCovModuleCtorName));
 297     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc);
 298   } else {
 299     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
 300   }
 301   return CtorFunc;
 302 }
 303
 304 bool SanitizerCoverageModule::runOnModule(Module &M) {
 305   if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
 306     return false;
 307   C = &(M.getContext());
 308   DL = &M.getDataLayout();
 309   CurModule = &M;
 310   CurModuleUniqueId = getUniqueModuleId(CurModule);
 311   TargetTriple = Triple(M.getTargetTriple());
 312   FunctionGuardArray = nullptr;
 313   Function8bitCounterArray = nullptr;
 314   FunctionPCsArray = nullptr;
 315   IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
 316   IntptrPtrTy = PointerType::getUnqual(IntptrTy);
 317   Type *VoidTy = Type::getVoidTy(*C);
 318   IRBuilder<> IRB(*C);
 319   Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty());
 320   Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
 321   Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
 322   Int64Ty = IRB.getInt64Ty();
 323   Int32Ty = IRB.getInt32Ty();
 324   Int16Ty = IRB.getInt16Ty();
 325   Int8Ty = IRB.getInt8Ty();
 326
 327   SanCovTracePCIndir = checkSanitizerInterfaceFunction(
 328       M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy));
 329   SanCovTraceCmpFunction[0] =
 330       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 331           SanCovTraceCmp1, VoidTy, IRB.getInt8Ty(), IRB.getInt8Ty()));
 332   SanCovTraceCmpFunction[1] = checkSanitizerInterfaceFunction(
 333       M.getOrInsertFunction(SanCovTraceCmp2, VoidTy, IRB.getInt16Ty(),
 334                             IRB.getInt16Ty()));
 335   SanCovTraceCmpFunction[2] = checkSanitizerInterfaceFunction(
 336       M.getOrInsertFunction(SanCovTraceCmp4, VoidTy, IRB.getInt32Ty(),
 337                             IRB.getInt32Ty()));
 338   SanCovTraceCmpFunction[3] =
 339       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 340           SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty));
 341
 342   SanCovTraceConstCmpFunction[0] =
 343       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 344           SanCovTraceConstCmp1, VoidTy, Int8Ty, Int8Ty));
 345   SanCovTraceConstCmpFunction[1] =
 346       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 347           SanCovTraceConstCmp2, VoidTy, Int16Ty, Int16Ty));
 348   SanCovTraceConstCmpFunction[2] =
 349       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 350           SanCovTraceConstCmp4, VoidTy, Int32Ty, Int32Ty));
 351   SanCovTraceConstCmpFunction[3] =
 352       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 353           SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty));
 354
 355   SanCovTraceDivFunction[0] =
 356       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 357           SanCovTraceDiv4, VoidTy, IRB.getInt32Ty()));
 358   SanCovTraceDivFunction[1] =
 359       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 360           SanCovTraceDiv8, VoidTy, Int64Ty));
 361   SanCovTraceGepFunction =
 362       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 363           SanCovTraceGep, VoidTy, IntptrTy));
 364   SanCovTraceSwitchFunction =
 365       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 366           SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy));
 367
 368   Constant *SanCovLowestStackConstant =
 369       M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy);
 370   SanCovLowestStack = cast<GlobalVariable>(SanCovLowestStackConstant);
 371   SanCovLowestStack->setThreadLocalMode(
 372       GlobalValue::ThreadLocalMode::InitialExecTLSModel);
 373   if (Options.StackDepth && !SanCovLowestStack->isDeclaration())
 374     SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy));
 375
 376   // Make sure smaller parameters are zero-extended to i64 as required by the
 377   // x86_64 ABI.
 378   if (TargetTriple.getArch() == Triple::x86_64) {
 379     for (int i = 0; i < 3; i++) {
 380       SanCovTraceCmpFunction[i]->addParamAttr(0, Attribute::ZExt);
 381       SanCovTraceCmpFunction[i]->addParamAttr(1, Attribute::ZExt);
 382       SanCovTraceConstCmpFunction[i]->addParamAttr(0, Attribute::ZExt);
 383       SanCovTraceConstCmpFunction[i]->addParamAttr(1, Attribute::ZExt);
 384     }
 385     SanCovTraceDivFunction[0]->addParamAttr(0, Attribute::ZExt);
 386   }
 387
 388
 389   // We insert an empty inline asm after cov callbacks to avoid callback merge.
 390   EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
 391                             StringRef(""), StringRef(""),
 392                             /*hasSideEffects=*/true);
 393
 394   SanCovTracePC = checkSanitizerInterfaceFunction(
 395       M.getOrInsertFunction(SanCovTracePCName, VoidTy));
 396   SanCovTracePCGuard = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 397       SanCovTracePCGuardName, VoidTy, Int32PtrTy));
 398
 399   for (auto &F : M)
 400     runOnFunction(F);
 401
 402   Function *Ctor = nullptr;
 403
 404   if (FunctionGuardArray)
 405     Ctor = CreateInitCallsForSections(M, SanCovTracePCGuardInitName, Int32PtrTy,
 406                                       SanCovGuardsSectionName);
 407   if (Function8bitCounterArray)
 408     Ctor = CreateInitCallsForSections(M, SanCov8bitCountersInitName, Int8PtrTy,
 409                                       SanCovCountersSectionName);
 410   if (Ctor && Options.PCTable) {
 411     auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrPtrTy);
 412     Function *InitFunction = declareSanitizerInitFunction(
 413         M, SanCovPCsInitName, {IntptrPtrTy, IntptrPtrTy});
 414     IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator());
 415     Value *SecStartPtr = nullptr;
 416     // Account for the fact that on windows-msvc __start_pc_table actually
 417     // points to a uint64_t before the start of the PC table.
 418     if (TargetTriple.getObjectFormat() == Triple::COFF) {
 419       auto SecStartI8Ptr = IRB.CreatePointerCast(SecStartEnd.first, Int8PtrTy);
 420       auto GEP = IRB.CreateGEP(SecStartI8Ptr,
 421                                ConstantInt::get(IntptrTy, sizeof(uint64_t)));
 422       SecStartPtr = IRB.CreatePointerCast(GEP, IntptrPtrTy);
 423     } else {
 424       SecStartPtr = IRB.CreatePointerCast(SecStartEnd.first, IntptrPtrTy);
 425     }
 426     IRBCtor.CreateCall(
 427         InitFunction,
 428         {SecStartPtr, IRB.CreatePointerCast(SecStartEnd.second, IntptrPtrTy)});
 429   }
 430   // We don't reference these arrays directly in any of our runtime functions,
 431   // so we need to prevent them from being dead stripped.
 432   if (TargetTriple.isOSBinFormatMachO())
 433     appendToUsed(M, GlobalsToAppendToUsed);
 434   appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed);
 435   return true;
 436 }
 437
 438 // True if block has successors and it dominates all of them.
 439 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) {
 440   if (succ_begin(BB) == succ_end(BB))
 441     return false;
 442
 443   for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) {
 444     if (!DT->dominates(BB, SUCC))
 445       return false;
 446   }
 447
 448   return true;
 449 }
 450
 451 // True if block has predecessors and it postdominates all of them.
 452 static bool isFullPostDominator(const BasicBlock *BB,
 453                                 const PostDominatorTree *PDT) {
 454   if (pred_begin(BB) == pred_end(BB))
 455     return false;
 456
 457   for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) {
 458     if (!PDT->dominates(BB, PRED))
 459       return false;
 460   }
 461
 462   return true;
 463 }
 464
 465 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB,
 466                                   const DominatorTree *DT,
 467                                   const PostDominatorTree *PDT,
 468                                   const SanitizerCoverageOptions &Options) {
 469   // Don't insert coverage for unreachable blocks: we will never call
 470   // __sanitizer_cov() for them, so counting them in
 471   // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
 472   // percentage. Also, unreachable instructions frequently have no debug
 473   // locations.
 474   if (isa<UnreachableInst>(BB->getTerminator()))
 475     return false;
 476
 477   // Don't insert coverage into blocks without a valid insertion point
 478   // (catchswitch blocks).
 479   if (BB->getFirstInsertionPt() == BB->end())
 480     return false;
 481
 482   if (Options.NoPrune || &F.getEntryBlock() == BB)
 483     return true;
 484
 485   if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function &&
 486       &F.getEntryBlock() != BB)
 487     return false;
 488
 489   // Do not instrument full dominators, or full post-dominators with multiple
 490   // predecessors.
 491   return !isFullDominator(BB, DT)
 492     && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor());
 493 }
 494
 495 bool SanitizerCoverageModule::runOnFunction(Function &F) {
 496   if (F.empty())
 497     return false;
 498   if (F.getName().find(".module_ctor") != std::string::npos)
 499     return false; // Should not instrument sanitizer init functions.
 500   if (F.getName().startswith("__sanitizer_"))
 501     return false;  // Don't instrument __sanitizer_* callbacks.
 502   // Don't touch available_externally functions, their actual body is elewhere.
 503   if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage)
 504     return false;
 505   // Don't instrument MSVC CRT configuration helpers. They may run before normal
 506   // initialization.
 507   if (F.getName() == "__local_stdio_printf_options" ||
 508       F.getName() == "__local_stdio_scanf_options")
 509     return false;
 510   if (isa<UnreachableInst>(F.getEntryBlock().getTerminator()))
 511     return false;
 512   // Don't instrument functions using SEH for now. Splitting basic blocks like
 513   // we do for coverage breaks WinEHPrepare.
 514   // FIXME: Remove this when SEH no longer uses landingpad pattern matching.
 515   if (F.hasPersonalityFn() &&
 516       isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn())))
 517     return false;
 518   if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge)
 519     SplitAllCriticalEdges(F);
 520   SmallVector<Instruction *, 8> IndirCalls;
 521   SmallVector<BasicBlock *, 16> BlocksToInstrument;
 522   SmallVector<Instruction *, 8> CmpTraceTargets;
 523   SmallVector<Instruction *, 8> SwitchTraceTargets;
 524   SmallVector<BinaryOperator *, 8> DivTraceTargets;
 525   SmallVector<GetElementPtrInst *, 8> GepTraceTargets;
 526
 527   const DominatorTree *DT =
 528       &getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
 529   const PostDominatorTree *PDT =
 530       &getAnalysis<PostDominatorTreeWrapperPass>(F).getPostDomTree();
 531   bool IsLeafFunc = true;
 532
 533   for (auto &BB : F) {
 534     if (shouldInstrumentBlock(F, &BB, DT, PDT, Options))
 535       BlocksToInstrument.push_back(&BB);
 536     for (auto &Inst : BB) {
 537       if (Options.IndirectCalls) {
 538         CallSite CS(&Inst);
 539         if (CS && !CS.getCalledFunction())
 540           IndirCalls.push_back(&Inst);
 541       }
 542       if (Options.TraceCmp) {
 543         if (isa<ICmpInst>(&Inst))
 544           CmpTraceTargets.push_back(&Inst);
 545         if (isa<SwitchInst>(&Inst))
 546           SwitchTraceTargets.push_back(&Inst);
 547       }
 548       if (Options.TraceDiv)
 549         if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst))
 550           if (BO->getOpcode() == Instruction::SDiv ||
 551               BO->getOpcode() == Instruction::UDiv)
 552             DivTraceTargets.push_back(BO);
 553       if (Options.TraceGep)
 554         if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst))
 555           GepTraceTargets.push_back(GEP);
 556       if (Options.StackDepth)
 557         if (isa<InvokeInst>(Inst) ||
 558             (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst)))
 559           IsLeafFunc = false;
 560     }
 561   }
 562
 563   InjectCoverage(F, BlocksToInstrument, IsLeafFunc);
 564   InjectCoverageForIndirectCalls(F, IndirCalls);
 565   InjectTraceForCmp(F, CmpTraceTargets);
 566   InjectTraceForSwitch(F, SwitchTraceTargets);
 567   InjectTraceForDiv(F, DivTraceTargets);
 568   InjectTraceForGep(F, GepTraceTargets);
 569   return true;
 570 }
 571
 572 Comdat *SanitizerCoverageModule::GetOrCreateFunctionComdat(Function &F) {
 573   if (auto Comdat = F.getComdat()) return Comdat;
 574   if (!TargetTriple.isOSBinFormatELF()) return nullptr;
 575   assert(F.hasName());
 576   std::string Name = F.getName();
 577   if (F.hasLocalLinkage()) {
 578     if (CurModuleUniqueId.empty()) return nullptr;
 579     Name += CurModuleUniqueId;
 580   }
 581   auto Comdat = CurModule->getOrInsertComdat(Name);
 582   F.setComdat(Comdat);
 583   return Comdat;
 584 }
 585
 586 GlobalVariable *SanitizerCoverageModule::CreateFunctionLocalArrayInSection(
 587     size_t NumElements, Function &F, Type *Ty, const char *Section) {
 588   ArrayType *ArrayTy = ArrayType::get(Ty, NumElements);
 589   auto Array = new GlobalVariable(
 590       *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage,
 591       Constant::getNullValue(ArrayTy), "__sancov_gen_");
 592   if (auto Comdat = GetOrCreateFunctionComdat(F))
 593     Array->setComdat(Comdat);
 594   Array->setSection(getSectionName(Section));
 595   Array->setAlignment(Ty->isPointerTy() ? DL->getPointerSize()
 596                                         : Ty->getPrimitiveSizeInBits() / 8);
 597   GlobalsToAppendToCompilerUsed.push_back(Array);
 598   MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F));
 599   Array->addMetadata(LLVMContext::MD_associated, *MD);
 600
 601   return Array;
 602 }
 603
 604 GlobalVariable *
 605 SanitizerCoverageModule::CreatePCArray(Function &F,
 606                                        ArrayRef<BasicBlock *> AllBlocks) {
 607   size_t N = AllBlocks.size();
 608   assert(N);
 609   SmallVector<Constant *, 32> PCs;
 610   IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt());
 611   for (size_t i = 0; i < N; i++) {
 612     if (&F.getEntryBlock() == AllBlocks[i]) {
 613       PCs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy));
 614       PCs.push_back((Constant *)IRB.CreateIntToPtr(
 615           ConstantInt::get(IntptrTy, 1), IntptrPtrTy));
 616     } else {
 617       PCs.push_back((Constant *)IRB.CreatePointerCast(
 618           BlockAddress::get(AllBlocks[i]), IntptrPtrTy));
 619       PCs.push_back((Constant *)IRB.CreateIntToPtr(
 620           ConstantInt::get(IntptrTy, 0), IntptrPtrTy));
 621     }
 622   }
 623   auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, IntptrPtrTy,
 624                                                     SanCovPCsSectionName);
 625   PCArray->setInitializer(
 626       ConstantArray::get(ArrayType::get(IntptrPtrTy, N * 2), PCs));
 627   PCArray->setConstant(true);
 628
 629   return PCArray;
 630 }
 631
 632 void SanitizerCoverageModule::CreateFunctionLocalArrays(
 633     Function &F, ArrayRef<BasicBlock *> AllBlocks) {
 634   if (Options.TracePCGuard) {
 635     FunctionGuardArray = CreateFunctionLocalArrayInSection(
 636         AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName);
 637     GlobalsToAppendToUsed.push_back(FunctionGuardArray);
 638   }
 639   if (Options.Inline8bitCounters)
 640     Function8bitCounterArray = CreateFunctionLocalArrayInSection(
 641         AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName);
 642   if (Options.PCTable)
 643     FunctionPCsArray = CreatePCArray(F, AllBlocks);
 644 }
 645
 646 bool SanitizerCoverageModule::InjectCoverage(Function &F,
 647                                              ArrayRef<BasicBlock *> AllBlocks,
 648                                              bool IsLeafFunc) {
 649   if (AllBlocks.empty()) return false;
 650   CreateFunctionLocalArrays(F, AllBlocks);
 651   for (size_t i = 0, N = AllBlocks.size(); i < N; i++)
 652     InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc);
 653   return true;
 654 }
 655
 656 // On every indirect call we call a run-time function
 657 // __sanitizer_cov_indir_call* with two parameters:
 658 //   - callee address,
 659 //   - global cache array that contains CacheSize pointers (zero-initialized).
 660 //     The cache is used to speed up recording the caller-callee pairs.
 661 // The address of the caller is passed implicitly via caller PC.
 662 // CacheSize is encoded in the name of the run-time function.
 663 void SanitizerCoverageModule::InjectCoverageForIndirectCalls(
 664     Function &F, ArrayRef<Instruction *> IndirCalls) {
 665   if (IndirCalls.empty())
 666     return;
 667   assert(Options.TracePC || Options.TracePCGuard || Options.Inline8bitCounters);
 668   for (auto I : IndirCalls) {
 669     IRBuilder<> IRB(I);
 670     CallSite CS(I);
 671     Value *Callee = CS.getCalledValue();
 672     if (isa<InlineAsm>(Callee))
 673       continue;
 674     IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy));
 675   }
 676 }
 677
 678 // For every switch statement we insert a call:
 679 // __sanitizer_cov_trace_switch(CondValue,
 680 //      {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
 681
 682 void SanitizerCoverageModule::InjectTraceForSwitch(
 683     Function &, ArrayRef<Instruction *> SwitchTraceTargets) {
 684   for (auto I : SwitchTraceTargets) {
 685     if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
 686       IRBuilder<> IRB(I);
 687       SmallVector<Constant *, 16> Initializers;
 688       Value *Cond = SI->getCondition();
 689       if (Cond->getType()->getScalarSizeInBits() >
 690           Int64Ty->getScalarSizeInBits())
 691         continue;
 692       Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases()));
 693       Initializers.push_back(
 694           ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits()));
 695       if (Cond->getType()->getScalarSizeInBits() <
 696           Int64Ty->getScalarSizeInBits())
 697         Cond = IRB.CreateIntCast(Cond, Int64Ty, false);
 698       for (auto It : SI->cases()) {
 699         Constant *C = It.getCaseValue();
 700         if (C->getType()->getScalarSizeInBits() <
 701             Int64Ty->getScalarSizeInBits())
 702           C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty);
 703         Initializers.push_back(C);
 704       }
 705       llvm::sort(Initializers.begin() + 2, Initializers.end(),
 706                  [](const Constant *A, const Constant *B) {
 707                    return cast<ConstantInt>(A)->getLimitedValue() <
 708                           cast<ConstantInt>(B)->getLimitedValue();
 709                  });
 710       ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size());
 711       GlobalVariable *GV = new GlobalVariable(
 712           *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage,
 713           ConstantArray::get(ArrayOfInt64Ty, Initializers),
 714           "__sancov_gen_cov_switch_values");
 715       IRB.CreateCall(SanCovTraceSwitchFunction,
 716                      {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)});
 717     }
 718   }
 719 }
 720
 721 void SanitizerCoverageModule::InjectTraceForDiv(
 722     Function &, ArrayRef<BinaryOperator *> DivTraceTargets) {
 723   for (auto BO : DivTraceTargets) {
 724     IRBuilder<> IRB(BO);
 725     Value *A1 = BO->getOperand(1);
 726     if (isa<ConstantInt>(A1)) continue;
 727     if (!A1->getType()->isIntegerTy())
 728       continue;
 729     uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType());
 730     int CallbackIdx = TypeSize == 32 ? 0 :
 731         TypeSize == 64 ? 1 : -1;
 732     if (CallbackIdx < 0) continue;
 733     auto Ty = Type::getIntNTy(*C, TypeSize);
 734     IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx],
 735                    {IRB.CreateIntCast(A1, Ty, true)});
 736   }
 737 }
 738
 739 void SanitizerCoverageModule::InjectTraceForGep(
 740     Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) {
 741   for (auto GEP : GepTraceTargets) {
 742     IRBuilder<> IRB(GEP);
 743     for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I)
 744       if (!isa<ConstantInt>(*I) && (*I)->getType()->isIntegerTy())
 745         IRB.CreateCall(SanCovTraceGepFunction,
 746                        {IRB.CreateIntCast(*I, IntptrTy, true)});
 747   }
 748 }
 749
 750 void SanitizerCoverageModule::InjectTraceForCmp(
 751     Function &, ArrayRef<Instruction *> CmpTraceTargets) {
 752   for (auto I : CmpTraceTargets) {
 753     if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
 754       IRBuilder<> IRB(ICMP);
 755       Value *A0 = ICMP->getOperand(0);
 756       Value *A1 = ICMP->getOperand(1);
 757       if (!A0->getType()->isIntegerTy())
 758         continue;
 759       uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
 760       int CallbackIdx = TypeSize == 8 ? 0 :
 761                         TypeSize == 16 ? 1 :
 762                         TypeSize == 32 ? 2 :
 763                         TypeSize == 64 ? 3 : -1;
 764       if (CallbackIdx < 0) continue;
 765       // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
 766       auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx];
 767       bool FirstIsConst = isa<ConstantInt>(A0);
 768       bool SecondIsConst = isa<ConstantInt>(A1);
 769       // If both are const, then we don't need such a comparison.
 770       if (FirstIsConst && SecondIsConst) continue;
 771       // If only one is const, then make it the first callback argument.
 772       if (FirstIsConst || SecondIsConst) {
 773         CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx];
 774         if (SecondIsConst)
 775           std::swap(A0, A1);
 776       }
 777
 778       auto Ty = Type::getIntNTy(*C, TypeSize);
 779       IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true),
 780               IRB.CreateIntCast(A1, Ty, true)});
 781     }
 782   }
 783 }
 784
 785 void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
 786                                                     size_t Idx,
 787                                                     bool IsLeafFunc) {
 788   BasicBlock::iterator IP = BB.getFirstInsertionPt();
 789   bool IsEntryBB = &BB == &F.getEntryBlock();
 790   DebugLoc EntryLoc;
 791   if (IsEntryBB) {
 792     if (auto SP = F.getSubprogram())
 793       EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP);
 794     // Keep static allocas and llvm.localescape calls in the entry block.  Even
 795     // if we aren't splitting the block, it's nice for allocas to be before
 796     // calls.
 797     IP = PrepareToSplitEntryBlock(BB, IP);
 798   } else {
 799     EntryLoc = IP->getDebugLoc();
 800   }
 801
 802   IRBuilder<> IRB(&*IP);
 803   IRB.SetCurrentDebugLocation(EntryLoc);
 804   if (Options.TracePC) {
 805     IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC.
 806     IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
 807   }
 808   if (Options.TracePCGuard) {
 809     auto GuardPtr = IRB.CreateIntToPtr(
 810         IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
 811                       ConstantInt::get(IntptrTy, Idx * 4)),
 812         Int32PtrTy);
 813     IRB.CreateCall(SanCovTracePCGuard, GuardPtr);
 814     IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
 815   }
 816   if (Options.Inline8bitCounters) {
 817     auto CounterPtr = IRB.CreateGEP(
 818         Function8bitCounterArray,
 819         {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
 820     auto Load = IRB.CreateLoad(CounterPtr);
 821     auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1));
 822     auto Store = IRB.CreateStore(Inc, CounterPtr);
 823     SetNoSanitizeMetadata(Load);
 824     SetNoSanitizeMetadata(Store);
 825   }
 826   if (Options.StackDepth && IsEntryBB && !IsLeafFunc) {
 827     // Check stack depth.  If it's the deepest so far, record it.
 828     Function *GetFrameAddr =
 829         Intrinsic::getDeclaration(F.getParent(), Intrinsic::frameaddress);
 830     auto FrameAddrPtr =
 831         IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)});
 832     auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy);
 833     auto LowestStack = IRB.CreateLoad(SanCovLowestStack);
 834     auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack);
 835     auto ThenTerm = SplitBlockAndInsertIfThen(IsStackLower, &*IP, false);
 836     IRBuilder<> ThenIRB(ThenTerm);
 837     auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack);
 838     SetNoSanitizeMetadata(LowestStack);
 839     SetNoSanitizeMetadata(Store);
 840   }
 841 }
 842
 843 std::string
 844 SanitizerCoverageModule::getSectionName(const std::string &Section) const {
 845   if (TargetTriple.getObjectFormat() == Triple::COFF) {
 846     if (Section == SanCovCountersSectionName)
 847       return ".SCOV$CM";
 848     if (Section == SanCovPCsSectionName)
 849       return ".SCOVP$M";
 850     return ".SCOV$GM"; // For SanCovGuardsSectionName.
 851   }
 852   if (TargetTriple.isOSBinFormatMachO())
 853     return "__DATA,__" + Section;
 854   return "__" + Section;
 855 }
 856
 857 std::string
 858 SanitizerCoverageModule::getSectionStart(const std::string &Section) const {
 859   if (TargetTriple.isOSBinFormatMachO())
 860     return "\1section$start$__DATA$__" + Section;
 861   return "__start___" + Section;
 862 }
 863
 864 std::string
 865 SanitizerCoverageModule::getSectionEnd(const std::string &Section) const {
 866   if (TargetTriple.isOSBinFormatMachO())
 867     return "\1section$end$__DATA$__" + Section;
 868   return "__stop___" + Section;
 869 }
 870
 871
 872 char SanitizerCoverageModule::ID = 0;
 873 INITIALIZE_PASS_BEGIN(SanitizerCoverageModule, "sancov",
 874                       "SanitizerCoverage: TODO."
 875                       "ModulePass",
 876                       false, false)
 877 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 878 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
 879 INITIALIZE_PASS_END(SanitizerCoverageModule, "sancov",
 880                     "SanitizerCoverage: TODO."
 881                     "ModulePass",
 882                     false, false)
 883 ModulePass *llvm::createSanitizerCoverageModulePass(
 884     const SanitizerCoverageOptions &Options) {
 885   return new SanitizerCoverageModule(Options);
 886 }