Re: segfault using _Unwind_ForcedUnwind()

[Oliver Kowalke <oliver dot kowalke at gmx dot de>]

Am 30.03.2012 17:08, schrieb Ian Lance Taylor:
> "Oliver Kowalke"<oliver.kowalke@gmx.de>  writes:
>
> > I get a segfault with following app - could you verify this?
> This program works fine for me (gcc 4.4.3, glibc 2.11.1, Ubuntu Lucid)
> in 64-bit mode.  But now I see that you are using 32-bit mode.  I can
> confirm that the program crashes for me in that mode.
>
> Looking at the 32-bit implementation of makecontext in glibc, I can see
> that the problem is that it doesn't set up correct unwind information
> for the parameters pushed on the stack.  The effect is that the first
> parameter on the stack appears to be a PC value.  I think this is a bug
> in glibc.  It should be possible to arrange for unwind information which
> skips %ebx words on the stack.
>
> Ian

I think the test app is not correct - on ppc32/linux it never returns.

Could you give me some hint how the stack unwind  information is usally 
writen on the stack/else where (some architectures do not save the 
return address on the stack).
I believe the code is somewhere in the gcc sources - unfortunately I 
don't know where (for what to grep for?)!

regards,
Oliver