[llvm] [HWASan] personality-thunk should inherit BTI/GCS/PAC flags via createWithDefaultAttr (PR #139216)

Fri May 9 00:17:52 PDT 2025

llvmbot wrote:




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

Author: None (zenshan)

<details>
<summary>Changes</summary>

Replace the Function::Create + manual BTI attribute logic(a76cf06) in instrumentPersonalityFunctions with Function::createWithDefaultAttr. This ensures that all module-level default attributes are automatically inherited by every __hwasan_personality_thunk.

Update personality-bti.ll to only verify that the branch protection flags are correctly propagated from module.flags into the thunk's attribute group.

---
Full diff: https://github.com/llvm/llvm-project/pull/139216.diff


2 Files Affected:

- (modified) llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp (+2-8) 
- (modified) llvm/test/Instrumentation/HWAddressSanitizer/personality-bti.ll (+15-11) 


``````````diff

diff --git a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
index 2f7712171bab2..b78fc114d45ca 100644
--- a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
@@ -1843,16 +1843,10 @@ void HWAddressSanitizer::instrumentPersonalityFunctions() {
         Int32Ty, {Int32Ty, Int32Ty, Int64Ty, PtrTy, PtrTy}, false);
     bool IsLocal = P.first && (!isa<GlobalValue>(P.first) ||
                                cast<GlobalValue>(P.first)->hasLocalLinkage());
-    auto *ThunkFn = Function::Create(ThunkFnTy,
+    auto *ThunkFn = Function::createWithDefaultAttr(ThunkFnTy,
                                      IsLocal ? GlobalValue::InternalLinkage
                                              : GlobalValue::LinkOnceODRLinkage,
-                                     ThunkName, &M);
-    // TODO: think about other attributes as well.
-    if (any_of(P.second, [](const Function *F) {
-          return F->hasFnAttribute("branch-target-enforcement");
-        })) {
-      ThunkFn->addFnAttr("branch-target-enforcement");
-    }
+                                     /*AddrSpace=*/0, ThunkName, &M);
     if (!IsLocal) {
       ThunkFn->setVisibility(GlobalValue::HiddenVisibility);
       ThunkFn->setComdat(M.getOrInsertComdat(ThunkName));
diff --git a/llvm/test/Instrumentation/HWAddressSanitizer/personality-bti.ll b/llvm/test/Instrumentation/HWAddressSanitizer/personality-bti.ll
index 3183a184c9d0d..4f7df1de6daf9 100644
--- a/llvm/test/Instrumentation/HWAddressSanitizer/personality-bti.ll
+++ b/llvm/test/Instrumentation/HWAddressSanitizer/personality-bti.ll
@@ -1,15 +1,22 @@
+; Test that HWASan personality-thunks correctly inherit branch protection attributes from module flags.
+
 ; RUN: opt < %s -mtriple aarch64-linux-android29 -passes=hwasan -S | FileCheck %s --check-prefix=NOPERS
 ; RUN: opt < %s -mtriple aarch64-linux-android30 -passes=hwasan -S | FileCheck %s --check-prefix=PERS
 
+!llvm.module.flags = !{!0, !1, !2}
+!0 = !{i32 8, !"branch-target-enforcement", i32 1}
+!1 = !{i32 8, !"guarded-control-stack",     i32 1}
+!2 = !{i32 8, !"sign-return-address",       i32 1}
+
 ; NOPERS: define void @nostack() #{{[0-9]+}} {
 ; PERS: define void @nostack() #{{[0-9]+}} {
-define void @nostack() sanitize_hwaddress "branch-target-enforcement" {
+define void @nostack() sanitize_hwaddress {
   ret void
 }
 
 ; NOPERS: define void @stack1() #{{[0-9]+}} {
 ; PERS: personality {{.*}} @__hwasan_personality_thunk
-define void @stack1() sanitize_hwaddress "branch-target-enforcement" {
+define void @stack1() sanitize_hwaddress {
   %p = alloca i8
   call void @sink(ptr %p)
   ret void
@@ -18,7 +25,7 @@ define void @stack1() sanitize_hwaddress "branch-target-enforcement" {
 
 ; NOPERS: personality ptr @global
 ; PERS: personality {{.*}} @__hwasan_personality_thunk.global
-define void @stack2() sanitize_hwaddress "branch-target-enforcement" personality ptr @global {
+define void @stack2() sanitize_hwaddress personality ptr @global {
   %p = alloca i8
   call void @sink(ptr %p)
   ret void
@@ -32,7 +39,7 @@ define internal void @local() {
 
 ; NOPERS: personality ptr @local
 ; PERS: personality {{.*}} @__hwasan_personality_thunk.local
-define void @stack3() sanitize_hwaddress "branch-target-enforcement" personality ptr @local {
+define void @stack3() sanitize_hwaddress personality ptr @local {
   %p = alloca i8
   call void @sink(ptr %p)
   ret void
@@ -40,7 +47,7 @@ define void @stack3() sanitize_hwaddress "branch-target-enforcement" personality
 
 ; NOPERS: personality ptr @local_alias
 ; PERS: personality {{.*}} @__hwasan_personality_thunk.local_alias
-define void @stack4() sanitize_hwaddress "branch-target-enforcement" personality ptr @local_alias {
+define void @stack4() sanitize_hwaddress personality ptr @local_alias {
   %p = alloca i8
   call void @sink(ptr %p)
   ret void
@@ -48,7 +55,7 @@ define void @stack4() sanitize_hwaddress "branch-target-enforcement" personality
 
 ; NOPERS: personality ptr inttoptr (i64 1 to ptr)
 ; PERS: personality ptr @__hwasan_personality_thunk.
-define void @stack5() sanitize_hwaddress "branch-target-enforcement" personality ptr inttoptr (i64 1 to ptr) {
+define void @stack5() sanitize_hwaddress personality ptr inttoptr (i64 1 to ptr) {
   %p = alloca i8
   call void @sink(ptr %p)
   ret void
@@ -56,7 +63,7 @@ define void @stack5() sanitize_hwaddress "branch-target-enforcement" personality
 
 ; NOPERS: personality ptr inttoptr (i64 2 to ptr)
 ; PERS: personality ptr @__hwasan_personality_thunk..1
-define void @stack6() sanitize_hwaddress "branch-target-enforcement" personality ptr inttoptr (i64 2 to ptr) {
+define void @stack6() sanitize_hwaddress personality ptr inttoptr (i64 2 to ptr) {
   %p = alloca i8
   call void @sink(ptr %p)
   ret void
@@ -65,9 +72,6 @@ define void @stack6() sanitize_hwaddress "branch-target-enforcement" personality
 declare void @global()
 declare void @sink(ptr)
 
-!llvm.module.flags = !{!0}
-!0 = !{i32 8, !"branch-target-enforcement", i32 1}
-
 ; PERS: define linkonce_odr hidden i32 @__hwasan_personality_thunk(i32 %0, i32 %1, i64 %2, ptr %3, ptr %4) [[ATTRS:#[0-9]+]] comdat
 ; PERS: %5 = tail call i32 @__hwasan_personality_wrapper(i32 %0, i32 %1, i64 %2, ptr %3, ptr %4, ptr null, ptr @_Unwind_GetGR, ptr @_Unwind_GetCFA)
 ; PERS: ret i32 %5
@@ -92,4 +96,4 @@ declare void @sink(ptr)
 ; PERS: %5 = tail call i32 @__hwasan_personality_wrapper(i32 %0, i32 %1, i64 %2, ptr %3, ptr %4, ptr inttoptr (i64 2 to ptr), ptr @_Unwind_GetGR, ptr @_Unwind_GetCFA)
 ; PERS: ret i32 %5
 
-; PERS: {{.*}}[[ATTRS]] = {{.*}}branch-target-enforcement
+; PERS: {{.*}}[[ATTRS]] = {{.*branch-target-enforcement.*guarded-control-stack.*sign-return-address}}

``````````

</details>


https://github.com/llvm/llvm-project/pull/139216
