[PATCH] D132691: [clang] Do not instrument the rtti_proxies under hwasan

[Leonard Chan via Phabricator via cfe-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rGcdb30f7a2635: [clang] Do not instrument the rtti_proxies under hwasan (authored by leonardchan).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D132691/new/

https://reviews.llvm.org/D132691

Files:
  clang/lib/CodeGen/CGVTables.cpp
  clang/lib/CodeGen/CGVTables.h
  clang/test/CodeGenCXX/RelativeVTablesABI/relative-vtables-hwasan.cpp


Index: clang/test/CodeGenCXX/RelativeVTablesABI/relative-vtables-hwasan.cpp
===================================================================
--- clang/test/CodeGenCXX/RelativeVTablesABI/relative-vtables-hwasan.cpp
+++ clang/test/CodeGenCXX/RelativeVTablesABI/relative-vtables-hwasan.cpp
@@ -6,6 +6,7 @@
 /// hwasan-instrumented.
 // CHECK-DAG: @_ZTV1A.local = private unnamed_addr constant { [3 x i32] } { [3 x i32] [i32 0, i32 trunc (i64 sub (i64 ptrtoint (ptr @_ZTI1A.rtti_proxy to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [3 x i32] }, ptr @_ZTV1A.local, i32 0, i32 0, i32 2) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr dso_local_equivalent @_ZN1A3fooEv to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [3 x i32] }, ptr @_ZTV1A.local, i32 0, i32 0, i32 2) to i64)) to i32)] }, no_sanitize_hwaddress, align 4
 // CHECK-DAG: @_ZTV1A = unnamed_addr alias { [3 x i32] }, ptr @_ZTV1A.local
+// CHECK-DAG: @_ZTI1A.rtti_proxy = hidden unnamed_addr constant ptr @_ZTI1A, no_sanitize_hwaddress, comdat
 
 class A {
 public:
@@ -21,6 +22,7 @@
 /// If the vtable happens to be hidden, then the alias is not needed. In this
 /// case, the original vtable struct itself should be unsanitized.
 // CHECK-DAG: @_ZTV1B = hidden unnamed_addr constant { [3 x i32] } { [3 x i32] [i32 0, i32 trunc (i64 sub (i64 ptrtoint (ptr @_ZTI1B.rtti_proxy to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [3 x i32] }, ptr @_ZTV1B, i32 0, i32 0, i32 2) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr dso_local_equivalent @_ZN1B3fooEv to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [3 x i32] }, ptr @_ZTV1B, i32 0, i32 0, i32 2) to i64)) to i32)] }, no_sanitize_hwaddress, align 4
+// CHECK-DAG: @_ZTI1B.rtti_proxy = hidden unnamed_addr constant ptr @_ZTI1B, no_sanitize_hwaddress, comdat
 
 class __attribute__((visibility("hidden"))) B {
 public:
Index: clang/lib/CodeGen/CGVTables.h
===================================================================
--- clang/lib/CodeGen/CGVTables.h
+++ clang/lib/CodeGen/CGVTables.h
@@ -155,8 +155,8 @@
   void GenerateRelativeVTableAlias(llvm::GlobalVariable *VTable,
                                    llvm::StringRef AliasNameRef);
 
-  /// Specify a vtable should not be instrumented with hwasan.
-  void RemoveHwasanMetadata(llvm::GlobalValue *VTable);
+  /// Specify a global should not be instrumented with hwasan.
+  void RemoveHwasanMetadata(llvm::GlobalValue *GV) const;
 };
 
 } // end namespace CodeGen
Index: clang/lib/CodeGen/CGVTables.cpp
===================================================================
--- clang/lib/CodeGen/CGVTables.cpp
+++ clang/lib/CodeGen/CGVTables.cpp
@@ -664,6 +664,12 @@
         proxy->setVisibility(llvm::GlobalValue::HiddenVisibility);
         proxy->setComdat(module.getOrInsertComdat(rttiProxyName));
       }
+      // Do not instrument the rtti proxies with hwasan to avoid a duplicate
+      // symbol error. Aliases generated by hwasan will retain the same namebut
+      // the addresses they are set to may have different tags from different
+      // compilation units. We don't run into this without hwasan because the
+      // proxies are in comdat groups, but those aren't propagated to the alias.
+      RemoveHwasanMetadata(proxy);
     }
     target = proxy;
   }
@@ -938,13 +944,13 @@
 // relocations. A future alternative for this would be finding which usages of
 // the vtable can continue to use the untagged hwasan value without any loss of
 // value in hwasan.
-void CodeGenVTables::RemoveHwasanMetadata(llvm::GlobalValue *VTable) {
+void CodeGenVTables::RemoveHwasanMetadata(llvm::GlobalValue *GV) const {
   if (CGM.getLangOpts().Sanitize.has(SanitizerKind::HWAddress)) {
     llvm::GlobalValue::SanitizerMetadata Meta;
-    if (VTable->hasSanitizerMetadata())
-      Meta = VTable->getSanitizerMetadata();
+    if (GV->hasSanitizerMetadata())
+      Meta = GV->getSanitizerMetadata();
     Meta.NoHWAddress = true;
-    VTable->setSanitizerMetadata(Meta);
+    GV->setSanitizerMetadata(Meta);
   }
 }
 


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