1 files changed, 12 insertions, 1 deletions
diff --git a/contrib/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.cc b/contrib/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.cc
index 84ff9d9d9e3b..7862575b37bb 100644
--- a/contrib/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.cc
+++ b/contrib/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.cc
@@ -83,7 +83,18 @@ void BufferedStackTrace::FastUnwindStack(uptr pc, uptr bp, uptr stack_top,
   while (IsValidFrame((uptr)frame, stack_top, bottom) &&
          IsAligned((uptr)frame, sizeof(*frame)) &&
          size < max_depth) {
+#ifdef __powerpc__
+    // PowerPC ABIs specify that the return address is saved at offset
+    // 16 of the *caller's* stack frame.  Thus we must dereference the
+    // back chain to find the caller frame before extracting it.
+    uhwptr *caller_frame = (uhwptr*)frame[0];
+    if (!IsValidFrame((uptr)caller_frame, stack_top, bottom) ||
+        !IsAligned((uptr)caller_frame, sizeof(uhwptr)))
+      break;
+    uhwptr pc1 = caller_frame[2];
+#else
     uhwptr pc1 = frame[1];
+#endif
     if (pc1 != pc) {
       trace_buffer[size++] = (uptr) pc1;
     }
@@ -107,7 +118,7 @@ void BufferedStackTrace::PopStackFrames(uptr count) {
 uptr BufferedStackTrace::LocatePcInTrace(uptr pc) {
   // Use threshold to find PC in stack trace, as PC we want to unwind from may
   // slightly differ from return address in the actual unwinded stack trace.
-  const int kPcThreshold = 304;
+  const int kPcThreshold = 320;
   for (uptr i = 0; i < size; ++i) {
     if (MatchPc(pc, trace[i], kPcThreshold))
       return i;