[llvm] [hwasan] Allow stack traces even when fixed shadow is used (PR #109344)

[Thurston Dang via llvm-commits]

https://github.com/thurstond created https://github.com/llvm/llvm-project/pull/109344

Previously, fixed shadow implied !InTls, and !InTls implied no stack traces, but InTls implied it would not use a fixed shadow. This patch changes fixed shadow to be compatible with stack traces.

It maintains the legacy behavior for KHWAsan || InstrumentWithCalls.

>From 934770dc4d978e57620ac539d473ca422b3a501a Mon Sep 17 00:00:00 2001
From: Thurston Dang <thurston at google.com>
Date: Thu, 19 Sep 2024 22:39:11 +0000
Subject: [PATCH] [hwasan] Allow stack traces even when fixed shadow is used

Previously, fixed shadow implied !InTls, and !InTls implied no stack traces, but InTls implied it would not use a fixed shadow.
This patch changes fixed shadow to be compatible with stack traces.

It maintains the legacy behavior for KHWAsan || InstrumentWithCalls.
---
 .../Instrumentation/HWAddressSanitizer.cpp      | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
index 7a5c690c7ea512..4bdf5b97aeb704 100644
--- a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
@@ -1340,7 +1340,7 @@ Value *HWAddressSanitizer::getFrameRecordInfo(IRBuilder<> &IRB) {
 }
 
 void HWAddressSanitizer::emitPrologue(IRBuilder<> &IRB, bool WithFrameRecord) {
-  if (!Mapping.InTls)
+  if (!Mapping.InTls || (Mapping.Offset != 0 && Mapping.Offset != kDynamicShadowSentinel))
     ShadowBase = getShadowNonTls(IRB);
   else if (!WithFrameRecord && TargetTriple.isAndroid())
     ShadowBase = getDynamicShadowIfunc(IRB);
@@ -1897,16 +1897,19 @@ void HWAddressSanitizer::ShadowMapping::init(Triple &TargetTriple,
     InTls = false;
     Offset = 0;
     WithFrameRecord = true;
-  } else if (ClMappingOffset.getNumOccurrences() > 0) {
-    InGlobal = false;
-    InTls = false;
-    Offset = ClMappingOffset;
-    WithFrameRecord = false;
   } else if (ClEnableKhwasan || InstrumentWithCalls) {
     InGlobal = false;
     InTls = false;
-    Offset = 0;
+    if (ClMappingOffset.getNumOccurrences() > 0)
+      Offset = ClMappingOffset;
+    else
+      Offset = 0;
     WithFrameRecord = false;
+  } else if (ClMappingOffset.getNumOccurrences() > 0) {
+    InGlobal = false;
+    InTls = true;
+    Offset = ClMappingOffset;
+    WithFrameRecord = true;
   } else if (ClWithIfunc) {
     InGlobal = true;
     InTls = false;