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SubjectRe: [PATCH v3 05/10] x86/fpu/xstate: Define new functions for clearing fpregs and xstates
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On Wed, 2020-04-29 at 18:39 +0200, Borislav Petkov wrote:
> On Wed, Apr 29, 2020 at 09:06:44AM -0700, Yu-cheng Yu wrote:
> > From: Fenghua Yu <fenghua.yu@intel.com>
> >
> > Currently, fpu__clear() clears all fpregs and xstates. Once XSAVES
> > supervisor states are introduced, supervisor settings (e.g. CET xstates)
> > must remain active for signals; 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.
> >
> > Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
> > Co-developed-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
> > Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
> > Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
> > Reviewed-by: Tony Luck <tony.luck@intel.com>
> >
> > v3:
> > - Put common code into a static function fpu__clear(), with a parameter
> > user_only.
> >
> > v2:
> > - Fixed an issue where fpu__clear_user_states() drops supervisor xstates.
> > - Revise commit log.
>
> Try applying that patch from this mail yourself and see whether the
> patch changelog will remain in the commit message or it will get
> discarded.

My mistake! I will fix it.

>
> > @@ -318,18 +313,40 @@ static inline void copy_init_fpstate_to_fpregs(void)
> > * Called by sys_execve(), by the signal handler code and by various
> > * error paths.
> > */
> > -void fpu__clear(struct fpu *fpu)
> > +static void fpu__clear(struct fpu *fpu, int user_only)
> > {
> > - WARN_ON_FPU(fpu != &current->thread.fpu); /* Almost certainly an anomaly */
> > + WARN_ON_FPU(fpu != &current->thread.fpu);
>
> Why did you remove the side comment?
>
> Is it wrong?
>
> Why do you do such arbitrary changes which are not needed instead of
> concentrating on only the changes the patch should do?

It has been some time since Thomas commented on this tail comment.
https://lore.kernel.org/lkml/alpine.DEB.2.21.1908161703010.1923@nanos.tec.linutronix.de/

I think why not fixing it while at it.

Yu-cheng

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