[ASan] Enable optional ASan recovery (LLVM core part)

[ygribov]

Summary

This patch adds support for recoverable ASan in LLVM. This is an addition to http://reviews.llvm.org/D12318

[eugenis]

Please add an IR test for the _noabort calls.

lib/Transforms/Instrumentation/AddressSanitizer.cpp

143

I'd remove these WARNINGS here and in the compiler-rt patch too. The whole "ASan" thing is use-at-your-own-risk, and this feature is not that much scarier than the rest.

1099

{}
I think we never do "if" w/o {} followed by "else" with {}.

[ygribov]

lib/Transforms/Instrumentation/AddressSanitizer.cpp

143

Ok, although Kostya may disagree here)

1099

Sorry, I remember you mentioning this last time.

[ygribov]

Minor fixes after review.

[ygribov]

Guys, is this one ok?

[eugenis]

Needs a test.

[ygribov]

Added a test.

[eugenis]

LGTM

test/Instrumentation/AddressSanitizer/keep_going.ll

9 ↗

(On Diff #39714)

Maybe also check that it is followed by a branch to the exit block, or that the basic block does not end with unreachable.

include/llvm/Transforms/Instrumentation.h

struct InstrProfOptions {
   std::string InstrProfileOutput;
 };
 
 /// Insert frontend instrumentation based profiling.
 ModulePass *createInstrProfilingPass(
     const InstrProfOptions &Options = InstrProfOptions());
 
 // Insert AddressSanitizer (address sanity checking) instrumentation
-FunctionPass *createAddressSanitizerFunctionPass(bool CompileKernel = false);
-ModulePass *createAddressSanitizerModulePass(bool CompileKernel = false);
+FunctionPass *createAddressSanitizerFunctionPass(bool CompileKernel = false,
+                                                 bool Recover = false);
+ModulePass *createAddressSanitizerModulePass(bool CompileKernel = false,
+                                             bool Recover = false);
 
 // Insert MemorySanitizer instrumentation (detection of uninitialized reads)
 FunctionPass *createMemorySanitizerPass(int TrackOrigins = 0);
 
 // Insert ThreadSanitizer (race detection) instrumentation
 FunctionPass *createThreadSanitizerPass();
 
 // Insert DataFlowSanitizer (dynamic data flow analysis) instrumentation

lib/Transforms/Instrumentation/AddressSanitizer.cpp

 static const size_t kNumberOfAccessSizes = 5;
 
 static const unsigned kAllocaRzSize = 32;
 
 // Command-line flags.
 static cl::opt<bool> ClEnableKasan(
     "asan-kernel", cl::desc("Enable KernelAddressSanitizer instrumentation"),
     cl::Hidden, cl::init(false));
+static cl::opt<bool> ClRecover(
+    "asan-recover",
+    cl::desc(
+        "Enable recovery mode (continue-after-error). "
+        "WARNING: USE AT YOUR OWN RISK!"),
+    cl::Hidden, cl::init(false));
 
 // This flag may need to be replaced with -f[no-]asan-reads.
 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
                                        cl::desc("instrument read instructions"),
                                        cl::Hidden, cl::init(true));
 static cl::opt<bool> ClInstrumentWrites(
     "asan-instrument-writes", cl::desc("instrument write instructions"),
     cl::Hidden, cl::init(true));

 static size_t RedzoneSizeForScale(int MappingScale) {
   // Redzone used for stack and globals is at least 32 bytes.
   // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
   return std::max(32U, 1U << MappingScale);
 }
 
 /// AddressSanitizer: instrument the code in module to find memory bugs.
 struct AddressSanitizer : public FunctionPass {
-  explicit AddressSanitizer(bool CompileKernel = false)
-      : FunctionPass(ID), CompileKernel(CompileKernel || ClEnableKasan) {
+  explicit AddressSanitizer(bool CompileKernel = false, bool Recover = false)
+      : FunctionPass(ID), CompileKernel(CompileKernel || ClEnableKasan),
+        Recover(Recover || ClRecover) {
     initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
   }
   const char *getPassName() const override {
     return "AddressSanitizerFunctionPass";
   }
   void getAnalysisUsage(AnalysisUsage &AU) const override {
     AU.addRequired<DominatorTreeWrapperPass>();
     AU.addRequired<TargetLibraryInfoWrapperPass>();
struct FunctionStateRAII {
     }
     ~FunctionStateRAII() { Pass->ProcessedAllocas.clear(); }
   };
 
   LLVMContext *C;
   Triple TargetTriple;
   int LongSize;
   bool CompileKernel;
+  bool Recover;
   Type *IntptrTy;
   ShadowMapping Mapping;
   DominatorTree *DT;
   Function *AsanCtorFunction = nullptr;
   Function *AsanInitFunction = nullptr;
   Function *AsanHandleNoReturnFunc;
   Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
   // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize).
   Function *AsanErrorCallback[2][2][kNumberOfAccessSizes];
   Function *AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
   // This array is indexed by AccessIsWrite and Experiment.
   Function *AsanErrorCallbackSized[2][2];
   Function *AsanMemoryAccessCallbackSized[2][2];
   Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
   InlineAsm *EmptyAsm;
   GlobalsMetadata GlobalsMD;
   DenseMap<AllocaInst *, bool> ProcessedAllocas;
 
   friend struct FunctionStackPoisoner;
 };
 
 class AddressSanitizerModule : public ModulePass {
  public:
-  explicit AddressSanitizerModule(bool CompileKernel = false)
-      : ModulePass(ID), CompileKernel(CompileKernel || ClEnableKasan) {}
+  explicit AddressSanitizerModule(bool CompileKernel = false,
+                                  bool Recover = false)
+      : ModulePass(ID), CompileKernel(CompileKernel || ClEnableKasan),
+        Recover(Recover || ClRecover) {}
   bool runOnModule(Module &M) override;
   static char ID;  // Pass identification, replacement for typeid
   const char *getPassName() const override { return "AddressSanitizerModule"; }
 
  private:
   void initializeCallbacks(Module &M);
 
   bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
   bool ShouldInstrumentGlobal(GlobalVariable *G);
   void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
   void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
   size_t MinRedzoneSizeForGlobal() const {
     return RedzoneSizeForScale(Mapping.Scale);
   }
 
   GlobalsMetadata GlobalsMD;
   bool CompileKernel;
+  bool Recover;
   Type *IntptrTy;
   LLVMContext *C;
   Triple TargetTriple;
   ShadowMapping Mapping;
   Function *AsanPoisonGlobals;
   Function *AsanUnpoisonGlobals;
   Function *AsanRegisterGlobals;
   Function *AsanUnregisterGlobals;
INITIALIZE_PASS_BEGIN(
     AddressSanitizer, "asan",
     "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
     false)
 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 INITIALIZE_PASS_END(
     AddressSanitizer, "asan",
     "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
     false)
-FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel) {
-  return new AddressSanitizer(CompileKernel);
+FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel,
+                                                       bool Recover) {
+  assert(!CompileKernel || Recover);
+  return new AddressSanitizer(CompileKernel, Recover);
 }
 
 char AddressSanitizerModule::ID = 0;
 INITIALIZE_PASS(
     AddressSanitizerModule, "asan-module",
     "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
     "ModulePass",
     false, false)
-ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel) {
-  return new AddressSanitizerModule(CompileKernel);
+ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel,
+                                                   bool Recover) {
+  assert(!CompileKernel || Recover);
+  return new AddressSanitizerModule(CompileKernel, Recover);
 }
 
 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
   size_t Res = countTrailingZeros(TypeSize / 8);
   assert(Res < kNumberOfAccessSizes);
   return Res;
 }
 
if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
     // We use branch weights for the slow path check, to indicate that the slow
     // path is rarely taken. This seems to be the case for SPEC benchmarks.
     TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
         Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
     assert(cast<BranchInst>(CheckTerm)->isUnconditional());
     BasicBlock *NextBB = CheckTerm->getSuccessor(0);
     IRB.SetInsertPoint(CheckTerm);
     Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
+    if (Recover)
+      CrashTerm = SplitBlockAndInsertIfThen(Cmp2, CheckTerm, false);
+    else {
       BasicBlock *CrashBlock =
         BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
       CrashTerm = new UnreachableInst(*C, CrashBlock);
       BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
       ReplaceInstWithInst(CheckTerm, NewTerm);
+    }
   } else {
-    CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
+    CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, !Recover);
   }
 
   Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
                                          AccessSizeIndex, SizeArgument, Exp);
   Crash->setDebugLoc(OrigIns->getDebugLoc());
 }
 
 // Instrument unusual size or unusual alignment.
void AddressSanitizer::initializeCallbacks(Module &M) {
   IRBuilder<> IRB(*C);
   // Create __asan_report* callbacks.
   // IsWrite, TypeSize and Exp are encoded in the function name.
   for (int Exp = 0; Exp < 2; Exp++) {
     for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
       const std::string TypeStr = AccessIsWrite ? "store" : "load";
       const std::string ExpStr = Exp ? "exp_" : "";
       const std::string SuffixStr = CompileKernel ? "N" : "_n";
-      const std::string EndingStr = CompileKernel ? "_noabort" : "";
+      const std::string EndingStr = Recover ? "_noabort" : "";
       Type *ExpType = Exp ? Type::getInt32Ty(*C) : nullptr;
-      // TODO(glider): for KASan builds add _noabort to error reporting
-      // functions and make them actually noabort (remove the UnreachableInst).
       AsanErrorCallbackSized[AccessIsWrite][Exp] =
           checkSanitizerInterfaceFunction(M.getOrInsertFunction(
-              kAsanReportErrorTemplate + ExpStr + TypeStr + SuffixStr,
+              kAsanReportErrorTemplate + ExpStr + TypeStr + SuffixStr + EndingStr,
               IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
       AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
           checkSanitizerInterfaceFunction(M.getOrInsertFunction(
               ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr,
               IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
       for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
            AccessSizeIndex++) {
         const std::string Suffix = TypeStr + itostr(1 << AccessSizeIndex);
         AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
             checkSanitizerInterfaceFunction(M.getOrInsertFunction(
-                kAsanReportErrorTemplate + ExpStr + Suffix,
+                kAsanReportErrorTemplate + ExpStr + Suffix + EndingStr,
                 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
         AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
             checkSanitizerInterfaceFunction(M.getOrInsertFunction(
                 ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr,
                 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
       }
     }
   }