Re: [Libunwind-devel] [RFC][patch] Fix crash in _ULx86_64_tdep_trace when sigaltstack is too far away

[Paul Pluzhnikov]

On Fri, Nov 11, 2011 at 5:06 AM, Lassi Tuura <address@hidden> wrote:

>> I don't see any major disadvantages for fix 3.
>
> Hum... In principle I agree. I do have the concern about 3 that the layout
> (and dwarf info) change depending on registers in use, specifically things
> like whether process is saving expensive (AVX etc.) registers or not.

I am not sure I understand.

The sigcontext_addr points to 'ucontext_t', and in the patch we fetch
the register state from there. Surely you are not suggesting that ucontext_t
layout changes depending on AVX use?

> I'm ok with the patch, but will try to check if my concerns matter at all.

Thanks.

> I think there's currently just one layout in use for the signal trampoline

The code in src/x86_64/Gos-linux.c certainly suggests that's the case.

> - and if there's more than one I am not sure we're ok to cache the delta
> in fast trace anyway, so fix 3 may be just as good a choice in the end.
>
> In any case, I won't have time to look at this before mid next week or so,
> and it's fine with me to include the patch into libunwind now.

No rush.

Thanks!
-- 
Paul Pluzhnikov