[PATCH 1/3] libc/x86: add dwarf-2 cfi unwinding information to syscalls

[Mike Frysinger]

On Sunday 20 November 2011 03:50:46 Timo Teräs wrote:
> Fixes unwinding of stack traces across system calls. Thus debuggers can
> show proper backtrace when inside a syscall.
> 
> Additionally, this fixes a race condition: if a signal happens while inside
> syscall, and the signal handler aborts the thread, we would have been
> unable to unwind the stack and run the proper error handler.
> 
> This patch also removes the "xchg ebx, register" trickery - it's very hard
> to add proper CFI info within macroes.  It apparently never worked 100%
> reliably, and the speed gain is probably insignificant on modern
> processors.

we should import the sysdeps/unix/sysv/linux/i386/sysdep.h logic from glibc to 
fix this.  they have the optimizations we want, and have cfi handling.
-mike
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 836 bytes
Desc: This is a digitally signed message part.
URL: <http://lists.busybox.net/pipermail/uclibc/attachments/20111120/3e815610/attachment.asc>