Re: Oops with tip/x86/fpu

Borislav Petkov
2015-03-04T20:07:28Z

On Wed, Mar 04, 2015 at 08:06:51PM +0100, Oleg Nesterov wrote:
> Thanks. I'll try to investigate tomorrow.
>
> Well, the kernel crashes because xrstor_state() is buggy, Quentin already
> has a fix.
>
> But #GP should be explained...

Could it be one of those conditions for which XRSTORS #GPs, like

"If XRSTORS attempts to load MXCSR with an illegal value, a
general-protection exception (#GP) occurs."

for example? I'm looking at the SDM section for XRSTORS.

I mean, math_state_restore() does init_fpu() and down that road we're
allocating an FPU state ... but we did init_fpu() before too, in
eager_fpu_init(). So what changed?

Maybe I'm looking in a totally wrong direction, it is too late here to
stare at FPU code anyway...

Thanks.

--
Regards/Gruss,
Boris.

ECO tip #101: Trim your mails when you reply.
--