[hwasan] Allow stack traces even when fixed shadow is used

[thurstond]

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.

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

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

Author: Thurston Dang (thurstond)

Changes

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.

---

Full diff: https://github.com/llvm/llvm-project/pull/109344.diff

1 Files Affected:

• (modified) llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp (+10-7)

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;

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[fmayer]

advance copy of nit, will think about the PR tomorrow

[fmayer]

Tests are failing

[vitalybuka]

Alternative set of patches:
#109616
#109617
#109618
#109619
#109620
#109621