[sanitizer] Use system unwinder in signal handlers on Android.

Because of the way Bionic sets up signal stack frames, libc unwinder is unable
to step through it, resulting in broken SEGV stack traces.

Luckily, libcorkscrew.so on Android implements an unwinder that can start with
a signal context, thus sidestepping the issue.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@201151 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 10 insertions, 5 deletions

diff --git a/lib/sanitizer_common/sanitizer_stacktrace_libcdep.cc b/lib/sanitizer_common/sanitizer_stacktrace_libcdep.cc
index ffc4f2ede..1b16c4dac 100644
--- a/lib/sanitizer_common/sanitizer_stacktrace_libcdep.cc
+++ b/lib/sanitizer_common/sanitizer_stacktrace_libcdep.cc
@@ -63,12 +63,17 @@ void StackTrace::PrintStack(const uptr *addr, uptr size) {
   Printf("\n");
 }
 
-void StackTrace::Unwind(uptr max_depth, uptr pc, uptr bp, uptr stack_top,
-                        uptr stack_bottom, bool request_fast_unwind) {
-  if (!WillUseFastUnwind(request_fast_unwind))
-    SlowUnwindStack(pc, max_depth);
-  else
+void StackTrace::Unwind(uptr max_depth, uptr pc, uptr bp, void *context,
+                        uptr stack_top, uptr stack_bottom,
+                        bool request_fast_unwind) {
+  if (!WillUseFastUnwind(request_fast_unwind)) {
+    if (context)
+      SlowUnwindStackWithContext(pc, context, max_depth);
+    else
+      SlowUnwindStack(pc, max_depth);
+  } else { 
     FastUnwindStack(pc, bp, stack_top, stack_bottom, max_depth);
+  }
 
   top_frame_bp = size ? bp : 0;
 }