Merge "Modify ip to get the instr being executed."
diff --git a/libc/bionic/debug_stacktrace.cpp b/libc/bionic/debug_stacktrace.cpp
index 71e876b..4100911 100644
--- a/libc/bionic/debug_stacktrace.cpp
+++ b/libc/bionic/debug_stacktrace.cpp
@@ -85,14 +85,14 @@
return _URC_NO_REASON;
}
-#if defined(__arm__)
- /*
- * The instruction pointer is pointing at the instruction after the bl(x), and
- * the _Unwind_Backtrace routine already masks the Thumb mode indicator (LSB
- * in PC). So we need to do a quick check here to find out if the previous
- * instruction is a Thumb-mode BLX(2). If so subtract 2 otherwise 4 from PC.
- */
+ // The instruction pointer is pointing at the instruction after the return
+ // call on all architectures.
+ // Modify the pc to point at the real function.
if (ip != 0) {
+#if defined(__arm__)
+ // We need to do a quick check here to find out if the previous
+ // instruction is a Thumb-mode BLX(2). If so subtract 2 otherwise
+ // 4 from PC.
short* ptr = reinterpret_cast<short*>(ip);
// Thumb BLX(2)
if ((*(ptr-1) & 0xff80) == 0x4780) {
@@ -100,8 +100,15 @@
} else {
ip -= 4;
}
- }
+#elif defined(__aarch64__)
+ // All instructions are 4 bytes long, skip back one instruction.
+ ip -= 4;
+#elif defined(__i386__) || defined(__x86_64__)
+ // It's difficult to decode exactly where the previous instruction is,
+ // so subtract 1 to estimate where the instruction lives.
+ ip--;
#endif
+ }
state->frames[state->frame_count++] = ip;
return (state->frame_count >= state->max_depth) ? _URC_END_OF_STACK : _URC_NO_REASON;