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Re: [rfc] Handle broken CFI for signal trampolines in libc on amd64-linux
- From: "Ulrich Weigand" <uweigand at de dot ibm dot com>
- To: drow at false dot org (Daniel Jacobowitz)
- Cc: gdb-patches at sourceware dot org
- Date: Fri, 21 Nov 2008 02:33:29 +0100 (CET)
- Subject: Re: [rfc] Handle broken CFI for signal trampolines in libc on amd64-linux
Daniel Jacobowitz wrote:
> On Fri, Nov 21, 2008 at 12:38:11AM +0100, Ulrich Weigand wrote:
> > Unfortunately even if I use the dwarf_signal_frame_p hook to have the
> > DWARF-2 sniffer recognize a SIGTRAMP_FRAME, it still doesn't work as
> > the __restore_rt CFI (at least in my glibc) only describes the unwind
> > effects as if it were a regular function, without taking into account
> > the restoring of registers by the sigreturn system call.
>
> What version of glibc is this? It was fixed two years ago this month:
Well, it's the system glibc of my openSUSE 10.2 install (based on
a 2006-10-12 glibc-2.5 snapshot), which is indeed somewhat over two
years old. I guess I could update to a more recent distro one of
these days ...
Anyway, while it is certainly good that this is fixed, I'm still
wondering why we should rely on that when we have a hard-coded
sigtramp detector that should be working just fine under any
circumstances.
Bye,
Ulrich
--
Dr. Ulrich Weigand
GNU Toolchain for Linux on System z and Cell BE
Ulrich.Weigand@de.ibm.com