Re: 32bit binaries on x86_64/Xen segfaults in syscall-vdso

From: Jeremy Fitzhardinge
Date: Fri Sep 04 2009 - 12:57:04 EST


On 09/04/09 09:20, Bastian Blank wrote:
> On Fri, Sep 04, 2009 at 09:07:39AM -0700, Jeremy Fitzhardinge wrote:
>
>> But for some reason that's triggering a failsafe callback, which invokes
>> a GP.
>>
> Hmm, not in my tests. It always returned to userspace correctly and died
> some operations later, usually the "ret". This then produced either a
> segfault (unreadable address), sigill (if it managed to reach the ELF
> header of the ld.so) or a GPF.

Hm, I may have misdiagnosed it then. Your symptoms are odd; either its
landing back in userspace in the right place but then stumbles on for a
while before crashing (wrong processor mode?) or the eip is wrong and
its just landing in the wrong place and crashing immediately.

How non-deterministic is it? Does it differ every time, or from boot to
boot, build to build?

J

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