[PATCH] D14724: [compiler-rt] [dfsan] Unify aarch64 mapping

[Adhemerval Zanella via llvm-commits]

zatrazz created this revision.
zatrazz added reviewers: aemerson, pcc, rengolin, kcc, samsonov, eugenis.
zatrazz added a subscriber: llvm-commits.
Herald added subscribers: rengolin, aemerson.

This patch reorganize the platform specific mapping information to
export the application mask on a external variable. This exported
variable will be used by intrumentation phase to create code to be
used on architecture with multiple VMA range.

The patch creates a new header, dfsan_platform.h, and move all the
mapping information and also create function accessors to the
mapping value. Also for aarch64 it initialize application exported
mask to the value based on runtime VMA detection.

http://reviews.llvm.org/D14724

Files:
  lib/Transforms/Instrumentation/DataFlowSanitizer.cpp

Index: lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
===================================================================
--- lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
+++ lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
@@ -72,15 +72,10 @@
 
 using namespace llvm;
 
-// VMA size definition for architecture that support multiple sizes.
-// AArch64 has 3 VMA sizes: 39, 42 and 48.
-#ifndef SANITIZER_AARCH64_VMA
-# define SANITIZER_AARCH64_VMA 39
-#else
-# if SANITIZER_AARCH64_VMA != 39 && SANITIZER_AARCH64_VMA != 42
-#  error "invalid SANITIZER_AARCH64_VMA size"
-# endif
-#endif
+// External symbol to be used when generating the shadow address for
+// architectures with multiple VMAs. Instead of using a constant integer
+// the runtime will set the external mask based on the VMA range.
+static const char *const kDFSanExternShadoPtrMask = "__dfsan_shadow_ptr_mask";
 
 // The -dfsan-preserve-alignment flag controls whether this pass assumes that
 // alignment requirements provided by the input IR are correct.  For example,
@@ -134,6 +129,15 @@
              "load or return with a nonzero label"),
     cl::Hidden);
 
+// Controls whether the instrumentation will use constant application mask
+// mask or read its value from a external variable to generate the shadow
+// address.
+static cl::opt<bool> ClRuntimeShadowMaskValue(
+    "dfsan-runtime-shadow-mask-value",
+    cl::desc("Use an external shadow mask value provided by the runtime "
+             "library."),
+    cl::Hidden, cl::init(false));
+
 namespace {
 
 StringRef GetGlobalTypeString(const GlobalValue &G) {
@@ -232,6 +236,7 @@
   IntegerType *ShadowTy;
   PointerType *ShadowPtrTy;
   IntegerType *IntptrTy;
+  IntegerType *IntTy;
   ConstantInt *ZeroShadow;
   ConstantInt *ShadowPtrMask;
   ConstantInt *ShadowPtrMul;
@@ -439,18 +444,16 @@
   ShadowTy = IntegerType::get(*Ctx, ShadowWidth);
   ShadowPtrTy = PointerType::getUnqual(ShadowTy);
   IntptrTy = DL.getIntPtrType(*Ctx);
+  IntTy = IntegerType::get(*Ctx, IntptrTy->getBitWidth());
   ZeroShadow = ConstantInt::getSigned(ShadowTy, 0);
   ShadowPtrMul = ConstantInt::getSigned(IntptrTy, ShadowWidth / 8);
   if (IsX86_64)
     ShadowPtrMask = ConstantInt::getSigned(IntptrTy, ~0x700000000000LL);
   else if (IsMIPS64)
     ShadowPtrMask = ConstantInt::getSigned(IntptrTy, ~0xF000000000LL);
+  // AArch64 supports multiple VMAs and the shadow mask is set at runtime.
   else if (IsAArch64)
-#if SANITIZER_AARCH64_VMA == 39
-    ShadowPtrMask = ConstantInt::getSigned(IntptrTy, ~0x7800000000LL);
-#else
-    ShadowPtrMask = ConstantInt::getSigned(IntptrTy, ~0x3c000000000LL);
-#endif
+    ClRuntimeShadowMaskValue = true;
   else
     report_fatal_error("unsupported triple");
 
@@ -938,9 +941,18 @@
 Value *DataFlowSanitizer::getShadowAddress(Value *Addr, Instruction *Pos) {
   assert(Addr != RetvalTLS && "Reinstrumenting?");
   IRBuilder<> IRB(Pos);
+  Value *ShadowPtrMaskValue;
+  if (ClRuntimeShadowMaskValue) {
+    Value *ExternalShadowMask =
+      Mod->getOrInsertGlobal(kDFSanExternShadoPtrMask, IntTy);
+    ShadowPtrMaskValue = IRB.CreateLoad(IntTy, ExternalShadowMask);
+  } else {
+    ShadowPtrMaskValue = ShadowPtrMask;
+  }
   return IRB.CreateIntToPtr(
       IRB.CreateMul(
-          IRB.CreateAnd(IRB.CreatePtrToInt(Addr, IntptrTy), ShadowPtrMask),
+          IRB.CreateAnd(IRB.CreatePtrToInt(Addr, IntptrTy),
+                        ShadowPtrMaskValue),
           ShadowPtrMul),
       ShadowPtrTy);
 }


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