Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [patch 0/8] x86/fpu: Mop up XSAVES and related damage | Date | Fri, 04 Jun 2021 16:05:18 +0200 |
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On Wed, Jun 02 2021 at 14:28, Yu-cheng Yu wrote: > On 6/2/2021 2:55 AM, Thomas Gleixner wrote: > > With the series applied, glibc pkey test fails sometimes. I will try to > find out the cause.
That fails not sometimes. It fails always due to patch 7/8. The reason is that before that patch fpu__clear_all() reinitialized the hardware which includes writing the initial PKRU value.
But fpu__initialize() does not store the initial PKRU value in the task's xstate which breaks PKRU. As that patch is not urgent we can postpone it for not.
But looking at the above, it's not clear to me why that PKRU stuff works at all (upstream), but I'll figure it out eventually. I'm quite sure that it does work by pure chance not by design.
Thanks,
tglx
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