[hwasan] Android: Switch from TLS_SLOT_TSAN(8) to TLS_SLOT_SANITIZER(6)

Summary:
The change is needed to support ELF TLS in Android. See D55581 for the
same change in compiler-rt.

Reviewers: srhines, eugenis

Reviewed By: eugenis

Subscribers: srhines, llvm-commits

Differential Revision: https://reviews.llvm.org/D55592

llvm-svn: 348983

llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp

@@ -703,10 +703,12 @@ Value *HWAddressSanitizer::untagPointer(IRBuilder<> &IRB, Value *PtrLong) {
 Value *HWAddressSanitizer::getHwasanThreadSlotPtr(IRBuilder<> &IRB, Type *Ty) {
   Module *M = IRB.GetInsertBlock()->getParent()->getParent();
   if (TargetTriple.isAArch64() && TargetTriple.isAndroid()) {
+    // Android provides a fixed TLS slot for sanitizers. See TLS_SLOT_SANITIZER
+    // in Bionic's libc/private/bionic_tls.h.
     Function *ThreadPointerFunc =
         Intrinsic::getDeclaration(M, Intrinsic::thread_pointer);
     Value *SlotPtr = IRB.CreatePointerCast(
-        IRB.CreateConstGEP1_32(IRB.CreateCall(ThreadPointerFunc), 0x40),
+        IRB.CreateConstGEP1_32(IRB.CreateCall(ThreadPointerFunc), 0x30),
         Ty->getPointerTo(0));
     return SlotPtr;
   }

llvm/test/Instrumentation/HWAddressSanitizer/prologue.ll

@@ -29,7 +29,7 @@ define i32 @test_load(i32* %a) sanitize_hwaddress {
 ; CHECK-GLOBAL: load i64, i64* @__hwasan_shadow_memory_dynamic_address
 
 ; CHECK-TLS:   %[[A:[^ ]*]] = call i8* @llvm.thread.pointer()
-; CHECK-TLS:   %[[B:[^ ]*]] = getelementptr i8, i8* %[[A]], i32 64
+; CHECK-TLS:   %[[B:[^ ]*]] = getelementptr i8, i8* %[[A]], i32 48
 ; CHECK-TLS:   %[[C:[^ ]*]] = bitcast i8* %[[B]] to i64*
 ; CHECK-TLS:   %[[D:[^ ]*]] = load i64, i64* %[[C]]
 ; CHECK-TLS:   %[[E:[^ ]*]] = or i64 %[[D]], 4294967295
@@ -60,7 +60,7 @@ define void @test_alloca() sanitize_hwaddress {
 ; CHECK-GLOBAL: load i64, i64* @__hwasan_shadow_memory_dynamic_address
 
 ; CHECK-TLS:   %[[A:[^ ]*]] = call i8* @llvm.thread.pointer()
-; CHECK-TLS:   %[[B:[^ ]*]] = getelementptr i8, i8* %[[A]], i32 64
+; CHECK-TLS:   %[[B:[^ ]*]] = getelementptr i8, i8* %[[A]], i32 48
 ; CHECK-TLS:   %[[C:[^ ]*]] = bitcast i8* %[[B]] to i64*
 ; CHECK-TLS:   %[[D:[^ ]*]] = load i64, i64* %[[C]]