Re: [rfc] Handle broken CFI for signal trampolines in libc on amd64-linux

["Ulrich Weigand" <uweigand@de.ibm.com>]

Mark Kettenis wrote:
> >  On Fri, Nov 21, 2008 at 02:33:29AM +0100, Ulrich Weigand wrote:
> > > 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.
> >
> >  I think that one reason was the extra work of the signal handler
> >  sniffer.  The amd64 one doesn't do much for named functions, though,
> >  and functions with CFI are likely to be named.  I suggest asking
> >  Mark Kettenis's opinion.
> 
> My memory is a bit hazy on this, but I think the idea was that the signal
> frame unwinder would only be used for older versions of linux/glibc that
> don't provide the necessary CFI, and that newer versions would provide
> correct CFI which would give the kernel/glibc people complete freedom on
> how to implement signal frames.  As such, I'm inclined to say "no" to your
> diff.

OK, fair enough.  As the bug is really in my copy of glibc anyway, I'll
withdraw my patch.

Bye,
Ulrich

-- 
  Dr. Ulrich Weigand
  GNU Toolchain for Linux on System z and Cell BE
  Ulrich.Weigand@de.ibm.com