[llvm-commits] [PATCH] ASan: support for zero-based shadow for PIE binaries (LLVM part).

[Alexey Samsonov]

Hi kcc,

1) Add one more option to ASan passes that tells if sources
will be linked with -pie, and ASan may use different shadow mapping
to increase performance.
2) Always tell shadow mapping and offset to the runtime.

http://llvm-reviews.chandlerc.com/D302

Files:
  include/llvm/Transforms/Instrumentation.h
  lib/Transforms/Instrumentation/AddressSanitizer.cpp

Index: include/llvm/Transforms/Instrumentation.h
===================================================================
--- include/llvm/Transforms/Instrumentation.h
+++ include/llvm/Transforms/Instrumentation.h
@@ -39,9 +39,11 @@
 // Insert AddressSanitizer (address sanity checking) instrumentation
 FunctionPass *createAddressSanitizerFunctionPass(
     bool CheckInitOrder = false, bool CheckUseAfterReturn = false,
-    bool CheckLifetime = false, StringRef BlacklistFile = StringRef());
+    bool CheckLifetime = false, StringRef BlacklistFile = StringRef(),
+    bool AssumePie = false);
 ModulePass *createAddressSanitizerModulePass(
-    bool CheckInitOrder = false, StringRef BlacklistFile = StringRef());
+    bool CheckInitOrder = false, StringRef BlacklistFile = StringRef(),
+    bool AssumePie = false);
 
 // Insert MemorySanitizer instrumentation (detection of uninitialized reads)
 FunctionPass *createMemorySanitizerPass(bool TrackOrigins = false,
Index: lib/Transforms/Instrumentation/AddressSanitizer.cpp
===================================================================
--- lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -193,13 +193,14 @@
   uint64_t Offset;
 };
 
-static ShadowMapping getShadowMapping(const Module &M, int LongSize) {
-  llvm::Triple targetTriple(M.getTargetTriple());
-  bool isAndroid = targetTriple.getEnvironment() == llvm::Triple::Android;
+static ShadowMapping getShadowMapping(const Module &M, int LongSize,
+                                      bool AssumePie) {
+  llvm::Triple TargetTriple(M.getTargetTriple());
+  bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
 
   ShadowMapping Mapping;
 
-  Mapping.Offset = isAndroid ? kDefaultShadowOffsetPie :
+  Mapping.Offset = (IsAndroid || AssumePie) ? kDefaultShadowOffsetPie :
       (LongSize == 32 ? kDefaultShadowOffset32 : kDefaultShadowOffset64);
   if (ClMappingOffsetLog >= 0) {
     // Zero offset log is the special case.
@@ -225,13 +226,15 @@
   AddressSanitizer(bool CheckInitOrder = false,
                    bool CheckUseAfterReturn = false,
                    bool CheckLifetime = false,
-                   StringRef BlacklistFile = StringRef())
+                   StringRef BlacklistFile = StringRef(),
+                   bool AssumePie = false)
       : FunctionPass(ID),
         CheckInitOrder(CheckInitOrder || ClInitializers),
         CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
         CheckLifetime(CheckLifetime || ClCheckLifetime),
         BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
-                                            : BlacklistFile) {}
+                                            : BlacklistFile),
+        AssumePie(AssumePie) {}
   virtual const char *getPassName() const {
     return "AddressSanitizerFunctionPass";
   }
@@ -265,15 +268,17 @@
   bool CheckInitOrder;
   bool CheckUseAfterReturn;
   bool CheckLifetime;
+  SmallString<64> BlacklistFile;
+  bool AssumePie;
+
   LLVMContext *C;
   DataLayout *TD;
   int LongSize;
   Type *IntptrTy;
   ShadowMapping Mapping;
   Function *AsanCtorFunction;
   Function *AsanInitFunction;
   Function *AsanHandleNoReturnFunc;
-  SmallString<64> BlacklistFile;
   OwningPtr<BlackList> BL;
   // This array is indexed by AccessIsWrite and log2(AccessSize).
   Function *AsanErrorCallback[2][kNumberOfAccessSizes];
@@ -286,11 +291,13 @@
 class AddressSanitizerModule : public ModulePass {
  public:
   AddressSanitizerModule(bool CheckInitOrder = false,
-                         StringRef BlacklistFile = StringRef())
+                         StringRef BlacklistFile = StringRef(),
+                         bool AssumePie = false)
       : ModulePass(ID),
         CheckInitOrder(CheckInitOrder || ClInitializers),
         BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
-                                            : BlacklistFile) {}
+                                            : BlacklistFile),
+        AssumePie(AssumePie) {}
   bool runOnModule(Module &M);
   static char ID;  // Pass identification, replacement for typeid
   virtual const char *getPassName() const {
@@ -309,6 +316,8 @@
 
   bool CheckInitOrder;
   SmallString<64> BlacklistFile;
+  bool AssumePie;
+
   OwningPtr<BlackList> BL;
   SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
   Type *IntptrTy;
@@ -473,18 +482,18 @@
     false, false)
 FunctionPass *llvm::createAddressSanitizerFunctionPass(
     bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
-    StringRef BlacklistFile) {
+    StringRef BlacklistFile, bool AssumePie) {
   return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
-                              CheckLifetime, BlacklistFile);
+                              CheckLifetime, BlacklistFile, AssumePie);
 }
 
 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 CheckInitOrder, StringRef BlacklistFile) {
-  return new AddressSanitizerModule(CheckInitOrder, BlacklistFile);
+    bool CheckInitOrder, StringRef BlacklistFile, bool AssumePie) {
+  return new AddressSanitizerModule(CheckInitOrder, BlacklistFile, AssumePie);
 }
 
 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
@@ -818,7 +827,7 @@
   C = &(M.getContext());
   int LongSize = TD->getPointerSizeInBits();
   IntptrTy = Type::getIntNTy(*C, LongSize);
-  Mapping = getShadowMapping(M, LongSize);
+  Mapping = getShadowMapping(M, LongSize, AssumePie);
   initializeCallbacks(M);
   DynamicallyInitializedGlobals.Init(M);
 
@@ -967,25 +976,20 @@
 }
 
 void AddressSanitizer::emitShadowMapping(Module &M, IRBuilder<> &IRB) const {
-  // Tell the values of mapping offset and scale to the run-time if they are
-  // specified by command-line flags.
-  if (ClMappingOffsetLog >= 0) {
-    GlobalValue *asan_mapping_offset =
-        new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
-                       ConstantInt::get(IntptrTy, Mapping.Offset),
-                       kAsanMappingOffsetName);
-    // Read the global, otherwise it may be optimized away.
-    IRB.CreateLoad(asan_mapping_offset, true);
-  }
-
-  if (ClMappingScale) {
-    GlobalValue *asan_mapping_scale =
-        new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
-                           ConstantInt::get(IntptrTy, Mapping.Scale),
-                           kAsanMappingScaleName);
-    // Read the global, otherwise it may be optimized away.
-    IRB.CreateLoad(asan_mapping_scale, true);
-  }
+  // Tell the values of mapping offset and scale to the run-time.
+  GlobalValue *asan_mapping_offset =
+      new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
+                     ConstantInt::get(IntptrTy, Mapping.Offset),
+                     kAsanMappingOffsetName);
+  // Read the global, otherwise it may be optimized away.
+  IRB.CreateLoad(asan_mapping_offset, true);
+
+  GlobalValue *asan_mapping_scale =
+      new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
+                         ConstantInt::get(IntptrTy, Mapping.Scale),
+                         kAsanMappingScaleName);
+  // Read the global, otherwise it may be optimized away.
+  IRB.CreateLoad(asan_mapping_scale, true);
 }
 
 // virtual
@@ -1013,7 +1017,7 @@
   AsanInitFunction->setLinkage(Function::ExternalLinkage);
   IRB.CreateCall(AsanInitFunction);
 
-  Mapping = getShadowMapping(M, LongSize);
+  Mapping = getShadowMapping(M, LongSize, AssumePie);
   emitShadowMapping(M, IRB);
 
   appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
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