Re: [uml-devel] Re: Uml showstopper bugs for 2.6.14

From: Blaisorblade
Date: Wed Sep 28 2005 - 11:41:36 EST


On Wednesday 28 September 2005 16:52, Jeff Dike wrote:
> On Wed, Sep 28, 2005 at 02:15:18PM +0200, Blaisorblade wrote:
> > Do you know when this was introduced, and the last working UML version?

> It's always been broken, I think.
Ah, but you're talking of SKAS0.

In this case (which seems strange, given the number of people using x86_64 and
not complaining - or maybe it's just me who didn't say "enable frame
pointers" to any of the various bug reports), if the patch is not trivial
enough (it seems to be), make sure to at least force frame pointers.

Even if I think, if I understood the thing correctly, that this workaround is
not even guaranteed to work.

> It results from the stub having to
> sigreturn by hand because it has no access to the libc restorer, and thus
> needing to restore the stack pointer to where it was on entry. I did this
> by popping the requisite number of times.

> Bodo fixed this for i386,
By restoring in sp the address of first param (or something like that), right?
> and
> I need to do something similar for x86_64.

The bug killing almost everybody testing 2.6.12-bb? In this case, it's SKAS0
specific.

But especially, couldn't this be triggered by another GCC version, changing
the stack layout?
> Jeff

--
Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!".
Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894)
http://www.user-mode-linux.org/~blaisorblade


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