Messages in this thread | | | Subject | Re: [patch 0/8] x86/fpu: Mop up XSAVES and related damage | From | "Yu, Yu-cheng" <> | Date | Fri, 4 Jun 2021 09:27:22 -0700 |
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On 6/4/2021 7:05 AM, Thomas Gleixner wrote: > 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 for the update. I will continue looking at it.
Yu-cheng
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