1 files changed, 32 insertions, 15 deletions

diff --git a/libsanitizer/sanitizer_common/sanitizer_stacktrace.cc b/libsanitizer/sanitizer_common/sanitizer_stacktrace.cc
index 0ce5ae475f6..9b99b5bb201 100644
--- a/libsanitizer/sanitizer_common/sanitizer_stacktrace.cc
+++ b/libsanitizer/sanitizer_common/sanitizer_stacktrace.cc
@@ -23,7 +23,7 @@ uptr StackTrace::GetPreviousInstructionPc(uptr pc) {
 #if defined(__powerpc__) || defined(__powerpc64__)
   // PCs are always 4 byte aligned.
   return pc - 4;
-#elif defined(__sparc__)
+#elif defined(__sparc__) || defined(__mips__)
   return pc - 8;
 #else
   return pc - 1;
@@ -34,6 +34,15 @@ uptr StackTrace::GetCurrentPc() {
   return GET_CALLER_PC();
 }
 
+void BufferedStackTrace::Init(const uptr *pcs, uptr cnt, uptr extra_top_pc) {
+  size = cnt + !!extra_top_pc;
+  CHECK_LE(size, kStackTraceMax);
+  internal_memcpy(trace_buffer, pcs, cnt * sizeof(trace_buffer[0]));
+  if (extra_top_pc)
+    trace_buffer[cnt] = extra_top_pc;
+  top_frame_bp = 0;
+}
+
 // Check if given pointer points into allocated stack area.
 static inline bool IsValidFrame(uptr frame, uptr stack_top, uptr stack_bottom) {
   return frame > stack_bottom && frame < stack_top - 2 * sizeof (uhwptr);
@@ -49,32 +58,40 @@ static inline uhwptr *GetCanonicFrame(uptr bp,
   if (!IsValidFrame(bp, stack_top, stack_bottom)) return 0;
   uhwptr *bp_prev = (uhwptr *)bp;
   if (IsValidFrame((uptr)bp_prev[0], stack_top, stack_bottom)) return bp_prev;
-  return bp_prev - 1;
+  // The next frame pointer does not look right. This could be a GCC frame, step
+  // back by 1 word and try again.
+  if (IsValidFrame((uptr)bp_prev[-1], stack_top, stack_bottom))
+    return bp_prev - 1;
+  // Nope, this does not look right either. This means the frame after next does
+  // not have a valid frame pointer, but we can still extract the caller PC.
+  // Unfortunately, there is no way to decide between GCC and LLVM frame
+  // layouts. Assume LLVM.
+  return bp_prev;
 #else
   return (uhwptr*)bp;
 #endif
 }
 
-void StackTrace::FastUnwindStack(uptr pc, uptr bp,
-                                 uptr stack_top, uptr stack_bottom,
-                                 uptr max_depth) {
+void BufferedStackTrace::FastUnwindStack(uptr pc, uptr bp, uptr stack_top,
+                                         uptr stack_bottom, uptr max_depth) {
   CHECK_GE(max_depth, 2);
-  trace[0] = pc;
+  trace_buffer[0] = pc;
   size = 1;
   if (stack_top < 4096) return;  // Sanity check for stack top.
   uhwptr *frame = GetCanonicFrame(bp, stack_top, stack_bottom);
-  uhwptr *prev_frame = 0;
+  // Lowest possible address that makes sense as the next frame pointer.
+  // Goes up as we walk the stack.
+  uptr bottom = stack_bottom;
   // Avoid infinite loop when frame == frame[0] by using frame > prev_frame.
-  while (frame > prev_frame &&
-         IsValidFrame((uptr)frame, stack_top, stack_bottom) &&
+  while (IsValidFrame((uptr)frame, stack_top, bottom) &&
          IsAligned((uptr)frame, sizeof(*frame)) &&
          size < max_depth) {
     uhwptr pc1 = frame[1];
     if (pc1 != pc) {
-      trace[size++] = (uptr) pc1;
+      trace_buffer[size++] = (uptr) pc1;
     }
-    prev_frame = frame;
-    frame = GetCanonicFrame((uptr)frame[0], stack_top, stack_bottom);
+    bottom = (uptr)frame;
+    frame = GetCanonicFrame((uptr)frame[0], stack_top, bottom);
   }
 }
 
@@ -82,15 +99,15 @@ static bool MatchPc(uptr cur_pc, uptr trace_pc, uptr threshold) {
   return cur_pc - trace_pc <= threshold || trace_pc - cur_pc <= threshold;
 }
 
-void StackTrace::PopStackFrames(uptr count) {
+void BufferedStackTrace::PopStackFrames(uptr count) {
   CHECK_LT(count, size);
   size -= count;
   for (uptr i = 0; i < size; ++i) {
-    trace[i] = trace[i + count];
+    trace_buffer[i] = trace_buffer[i + count];
   }
 }
 
-uptr StackTrace::LocatePcInTrace(uptr pc) {
+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 = 288;