[asan] Fix size/alignment issues with non-default shadow scale

Fix a couple places where the minimum alignment/size should be a
function of the shadow granularity:
- alignment of AllGlobals
- the minimum left redzone size on the stack

Added a test to verify that the metadata_array is properly aligned
for shadow scale of 5, to be enabled when we add build support
for testing shadow scale of 5.

Differential Revision: https://reviews.llvm.org/D39470

llvm-svn: 318395

2 files changed, 7 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 967464f989f..190efce225a 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -1978,6 +1978,8 @@ void AddressSanitizerModule::InstrumentGlobalsWithMetadataArray(
   auto AllGlobals = new GlobalVariable(
       M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
       ConstantArray::get(ArrayOfGlobalStructTy, MetadataInitializers), "");
+  if (Mapping.Scale > 3)
+    AllGlobals->setAlignment(1ULL << Mapping.Scale);
 
   IRB.CreateCall(AsanRegisterGlobals,
                  {IRB.CreatePointerCast(AllGlobals, IntptrTy),
@@ -2817,9 +2819,10 @@ void FunctionStackPoisoner::processStaticAllocas() {
 
   // Minimal header size (left redzone) is 4 pointers,
   // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
-  size_t MinHeaderSize = ASan.LongSize / 2;
+  size_t Granularity = 1ULL << Mapping.Scale;
+  size_t MinHeaderSize = std::max((size_t)ASan.LongSize / 2, Granularity);
   const ASanStackFrameLayout &L =
-      ComputeASanStackFrameLayout(SVD, 1ULL << Mapping.Scale, MinHeaderSize);
+      ComputeASanStackFrameLayout(SVD, Granularity, MinHeaderSize);
 
   // Build AllocaToSVDMap for ASanStackVariableDescription lookup.
   DenseMap<const AllocaInst *, ASanStackVariableDescription *> AllocaToSVDMap;
diff --git a/llvm/test/Instrumentation/AddressSanitizer/global_metadata_array.ll b/llvm/test/Instrumentation/AddressSanitizer/global_metadata_array.ll
index 8b70fa29880..9d2d5e50e5a 100644
--- a/llvm/test/Instrumentation/AddressSanitizer/global_metadata_array.ll
+++ b/llvm/test/Instrumentation/AddressSanitizer/global_metadata_array.ll
@@ -24,6 +24,8 @@ target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 ; Check that location descriptors and global names were passed into __asan_register_globals:
 ; CHECK: i64 ptrtoint ([7 x i8]* [[VARNAME]] to i64)
 ; CHECK: i64 ptrtoint ({ [22 x i8]*, i32, i32 }* [[LOCDESCR]] to i64)
+; Check alignment of metadata_array.
+; CHECK-S5-SAME: {{align 32$}}
 
 ; Function Attrs: nounwind sanitize_address
 define internal void @__cxx_global_var_init() #0 section ".text.startup" {