Re: [PATCH 5/6] x86/fpu/xstate: Define new functions for clearing fpregs and xstates

[Borislav Petkov]

On Wed, Sep 25, 2019 at 08:10:21AM -0700, Yu-cheng Yu wrote:
> From: Fenghua Yu <fenghua.yu@xxxxxxxxx>
> 
> Currently, fpu__clear() clears all fpregs and xstates.  Once XSAVES
> supervisor states are introduced, supervisor settings must remain active
> for signals;

I could very well use an example here: for signal handling supervisor
states, I'm guessing this would be something CET-related so some text
about a usage scenario would be very helpful here.

> it is necessary to have separate functions:
> 
>  - Create fpu__clear_user_states(): clear only user settings for signals;
>  - Create fpu__clear_all(): clear both user and supervisor settings in
>    flush_thread().
> 
> Also modify copy_init_fpstate_to_fpregs() to take a mask from above two
> functions.
> 
> Co-developed-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
> Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>

As before...

-- 
Regards/Gruss,
    Boris.

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