Messages in this thread | | | Date | Wed, 1 Feb 2023 19:18:22 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH v5 06/39] x86/fpu: Add helper for modifying xstate |
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On Wed, Feb 01, 2023 at 05:31:50PM +0000, Edgecombe, Rick P wrote: > On Wed, 2023-02-01 at 12:01 +0100, Borislav Petkov wrote: > > On Thu, Jan 19, 2023 at 01:22:44PM -0800, Rick Edgecombe wrote: > > > +void fpregs_lock_and_load(void) > > > +{ > > > + /* > > > + * fpregs_lock() only disables preemption (mostly). So > > > modifying state > > > + * in an interrupt could screw up some in progress fpregs > > > operation, > > > + * but appear to work. Warn about it. > > > > I don't like comments where it sounds like we don't know what we're > > doing. "Appear to work"? > > I can change it. This patch started with the observation that modifying > xstate from the kernel had been gotten wrong a couple times in the > past, so that is what this is referencing. Since then, the fancy > automatic solution got boiled down to this helper and a couple > warnings.
Yeah, but that comment right now reads like: modifying in interrupt context can corrupt fpregs and you should not do it but it kinda works, by chance. Thus encouraging people to keep doing that.
I guess "but appear to work" can go and then it is fine.
Thx.
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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