[PATCH] D18895: [sanitizer] [SystemZ] Fix stack traces.

[Marcin Kościelnicki via llvm-commits]

koriakin created this revision.
koriakin added reviewers: uweigand, samsonov, eugenis.
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koriakin added a project: Sanitizers.

On s390, the return address is in %r14, which is saved 14 words from
the frame pointer.

Unfortunately, there's no way to do a proper fast backtrace on SystemZ
with current LLVM - the saved %r15 in fixed-layout register save
area points to the containing frame itself, and not to the next one.
Likewise for %r11 - it's identical to %r15, unless alloca is used
(and even if it is, it's still useless).  There's just no way to
determine frame size / next frame pointer.  -mbackchain would fix that
(and make the current code just work), but that's not yet supported
in LLVM.  The end result is that stack traces show only 2 functions.
We will thus need to XFAIL some asan tests
(Linux/stack-trace-dlclose.cc, deep_stack_uaf.cc).


Repository:
  rL LLVM

http://reviews.llvm.org/D18895

Files:
  lib/sanitizer_common/sanitizer_stacktrace.cc

Index: lib/sanitizer_common/sanitizer_stacktrace.cc
===================================================================
--- lib/sanitizer_common/sanitizer_stacktrace.cc
+++ lib/sanitizer_common/sanitizer_stacktrace.cc
@@ -92,6 +92,8 @@
         !IsAligned((uptr)caller_frame, sizeof(uhwptr)))
       break;
     uhwptr pc1 = caller_frame[2];
+#elif defined(__s390__)
+    uhwptr pc1 = frame[14];
 #else
     uhwptr pc1 = frame[1];
 #endif


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