Re: [PATCH 1/1] x86/fpu: x86/fpu: avoid math_state_restore() without used_math() in __restore_xstate_sig()

From: Borislav Petkov
Date: Mon Mar 09 2015 - 12:55:08 EST

On Mon, Mar 09, 2015 at 05:24:04PM +0100, Oleg Nesterov wrote:
> Well, this is the same thinhg reported by Dave ;)

Am I the only one in thinking that this FPU thing went completely nuts?!
Just kill it all and let's start from scratch. :-P

> It is not fixed by Quentin's patch.
> This patch "fixes" the problem in a sense that the kernel won't crash
> after restore_fpu_checking() triggers #GP. Before this patch
> do_general_protection()->fixup_exception() does not work in this case
> and the kernel panics.
> But restore_fpu_checking() should not trigger #GP (and fail).



> But this too doesn't fix the problem: fpu_finit() is buggy on Dave's
> machine.

In talking about fpu_finit() - I still have two cleanup patches queued
from you:



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