[NFC] [HWASan] make getAndroidSlotPtr function generic

[fmayer]

This is so we can use a different slot for stack MTE.

[llvmbot]

@llvm/pr-subscribers-compiler-rt-sanitizer

@llvm/pr-subscribers-llvm-transforms

Author: Florian Mayer (fmayer)

Changes

This is so we can use a different slot for stack MTE.

---

Full diff: https://github.com/llvm/llvm-project/pull/86200.diff

3 Files Affected:

• (modified) llvm/include/llvm/Transforms/Utils/MemoryTaggingSupport.h (+1-1)
• (modified) llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp (+4-1)
• (modified) llvm/lib/Transforms/Utils/MemoryTaggingSupport.cpp (+2-2)

diff --git a/llvm/include/llvm/Transforms/Utils/MemoryTaggingSupport.h b/llvm/include/llvm/Transforms/Utils/MemoryTaggingSupport.h
index 158c358a9e4618..fb3ab33a0629da 100644
--- a/llvm/include/llvm/Transforms/Utils/MemoryTaggingSupport.h
+++ b/llvm/include/llvm/Transforms/Utils/MemoryTaggingSupport.h
@@ -84,7 +84,7 @@ bool isLifetimeIntrinsic(Value *V);
 Value *readRegister(IRBuilder<> &IRB, StringRef Name);
 Value *getFP(IRBuilder<> &IRB);
 Value *getPC(const Triple &TargetTriple, IRBuilder<> &IRB);
-Value *getAndroidSanitizerSlotPtr(IRBuilder<> &IRB);
+Value *getAndroidSlotPtr(IRBuilder<> &IRB, int Slot);
 
 } // namespace memtag
 } // namespace llvm
diff --git a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
index 3c95610fa3e80b..3b0d99abd0cd0c 100644
--- a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
@@ -1220,8 +1220,11 @@ Value *HWAddressSanitizer::untagPointer(IRBuilder<> &IRB, Value *PtrLong) {
 }
 
 Value *HWAddressSanitizer::getHwasanThreadSlotPtr(IRBuilder<> &IRB) {
+  // Android provides a fixed TLS slot for sanitizers. See TLS_SLOT_SANITIZER
+  // in Bionic's libc/platform/bionic/tls_defines.h.
+  constexpr int SanitizerSlot = 6;
   if (TargetTriple.isAArch64() && TargetTriple.isAndroid())
-    return memtag::getAndroidSanitizerSlotPtr(IRB);
+    return memtag::getAndroidSlotPtr(IRB, SanitizerSlot);
   return ThreadPtrGlobal;
 }
 
diff --git a/llvm/lib/Transforms/Utils/MemoryTaggingSupport.cpp b/llvm/lib/Transforms/Utils/MemoryTaggingSupport.cpp
index fd94a120bc6655..7b1eb70168d894 100644
--- a/llvm/lib/Transforms/Utils/MemoryTaggingSupport.cpp
+++ b/llvm/lib/Transforms/Utils/MemoryTaggingSupport.cpp
@@ -273,14 +273,14 @@ Value *getFP(IRBuilder<> &IRB) {
       IRB.getIntPtrTy(M->getDataLayout()));
 }
 
-Value *getAndroidSanitizerSlotPtr(IRBuilder<> &IRB) {
+Value *getAndroidSlotPtr(IRBuilder<> &IRB, int Slot) {
   Module *M = IRB.GetInsertBlock()->getParent()->getParent();
   // 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);
   return IRB.CreateConstGEP1_32(IRB.getInt8Ty(),
-                                IRB.CreateCall(ThreadPointerFunc), 0x30);
+                                IRB.CreateCall(ThreadPointerFunc), 8 * Slot);
 }
 
 } // namespace memtag

[vitalybuka]

would be better to use IRB.getIntPtrTy() and avoid 8* ?

[fmayer]

Hmm, in which case getPtrTy is probably more correct, because that's what it is in AOSP https://cs.android.com/android/platform/superproject/main/+/main:bionic/libc/private/bionic_tls.h;l=60;drc=f5f04b19fe59f6ac3f0b94fc890d0ccff6821fa8

[fmayer]

That changes tests, which makes this non-NFC. Let's not do in this patch.