libsanitizer: Apply local patches

1 files changed, 12 insertions, 5 deletions

diff --git a/libsanitizer/sanitizer_common/sanitizer_stacktrace.cpp b/libsanitizer/sanitizer_common/sanitizer_stacktrace.cpp
index 37e9e6dd08d..5a12422fc6f 100644
--- a/libsanitizer/sanitizer_common/sanitizer_stacktrace.cpp
+++ b/libsanitizer/sanitizer_common/sanitizer_stacktrace.cpp
@@ -86,8 +86,8 @@ static inline uhwptr *GetCanonicFrame(uptr bp,
   // 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;
+  // layouts. Assume GCC.
+  return bp_prev - 1;
 #else
   return (uhwptr*)bp;
 #endif
@@ -110,14 +110,21 @@ void BufferedStackTrace::UnwindFast(uptr pc, uptr bp, uptr stack_top,
          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.
+    // PowerPC ABIs specify that the return address is saved on 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;
+    // For most ABIs the offset where the return address is saved is two
+    // register sizes.  The exception is the SVR4 ABI, which uses an
+    // offset of only one register size.
+#ifdef _CALL_SYSV
+    uhwptr pc1 = caller_frame[1];
+#else
     uhwptr pc1 = caller_frame[2];
+#endif
 #elif defined(__s390__)
     uhwptr pc1 = frame[14];
 #elif defined(__riscv)