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


>  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.


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