Re: [Crash-utility] [PATCH] Use backtrace() instead of __builtin_return_address()

When crash is compiled with gcc 4.3 and -O2, the __builtin_return_address() causes crash to crash. See also [1] for a discussion about that.

The gcc documentation [2] says __builtin_return_address() On some machines it may be impossible to determine the return address of any function other than the current one; in such cases, or when the top of the stack has been reached, this function will return 0 or a random value. In addition, __builtin_frame_address may be used to determine if the top of the stack has been reached. This function should only be used with a nonzero argument for debugging purposes. Even the __builtin_frame_address() does not work here. Instead of checking if the crash is built with -O2 and introducing new preprocessor checks here, I use the backtrace() function which is available via glibc. This works here (tested without the other patch which brought my attention to this bug). Since crash only runs on Linux (IIRC), the glibc dependency should not be a problem. Signed-off-by: Bernhard Walle <bwalle(a)suse.de&gt; [1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=165992 [2] http://gcc.gnu.org/onlinedocs/gcc/Return-Address.html --- defs.h | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) --- a/defs.h +++ b/defs.h @@ -1803,15 +1803,7 @@ struct alias_data { /* c static inline void save_return_address(ulong *retaddr) { - retaddr[0] = (ulong) __builtin_return_address(0); -#if defined(X86) || defined(PPC) || defined(X86_64) || defined(PPC64) - if (__builtin_frame_address(1)) - retaddr[1] = (ulong) __builtin_return_address(1); - if (__builtin_frame_address(2)) - retaddr[2] = (ulong) __builtin_return_address(2); - if (__builtin_frame_address(3)) - retaddr[3] = (ulong) __builtin_return_address(3); -#endif + backtrace(retaddr, 4); } #endif /* !GDB_COMMON */ -- Crash-utility mailing list Crash-utility(a)redhat.com https://www.redhat.com/mailman/listinfo/crash-utility