Re: Stepping out of signal handler problem

[Mark Kettenis <mark.kettenis@xs4all.nl>]

> Date: Fri, 16 May 2008 14:48:36 -0400
> From: Aleksandar Ristovski <aristovski@qnx.com>
> 
> Mark Kettenis wrote:
> >> From: Aleksandar Ristovski <aristovski@qnx.com>
> >> Date:  Fri, 16 May 2008 12:26:43 -0400
> >>
> >> This makes question 2: Is the only way to implement this similar to
> >> linux-nat (scanning for sigreturn kernel call)? Is there anything
> >> 'cleaner'?
> > 
> > The clean way of doing this is provide proper unwind info for the
> > signal trampoline.  This shouldn't be too difficult if your signal
> > trampolines live in libc, and quite a bit harder if they are in the
> > kernel.
> > 
> 
> What is the preferred way: frame_unwind_append_sniffer or
> tramp_frame_prepend_unwinder?

Neither.  I was referring to the possibility to generate DWARF2 frame
info for the signal trampoline.  This is what is done in glibc, the
Linux C library.  We also have a test for this in the GDB testsuite
(gdb.arch/i386-signal.c).

The nice thing about this approach is that it avoids hardcoding the
signal frame layout in GDB, making it possible to change the
implementation without having to adjust GDB.