Messages in this thread | | | Date | Mon, 2 May 2022 15:16:16 +0200 | From | Borislav Petkov <> | Subject | Re: [patch 1/3] x86/fpu: Prevent FPU state corruption |
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On Sun, May 01, 2022 at 09:31:43PM +0200, Thomas Gleixner wrote: > The latter is checking whether some other context already uses FPU in the > kernel, but if that's not the case then it allows FPU to be used > unconditionally even if the calling context interupted a fpregs_lock()
Unknown word [interupted] in commit message. Suggestions: ['interrupted', ...
> /* > * Can we use the FPU in kernel mode with the > * whole "kernel_fpu_begin/end()" sequence?
While at it, drop the "we": "Can the FPU be used in kernel mode... "
> - * > - * It's always ok in process context (ie "not interrupt") > - * but it is sometimes ok even from an irq. > */ > bool irq_fpu_usable(void) > { > - return !in_interrupt() || > - interrupted_user_mode() || > - interrupted_kernel_fpu_idle(); > + if (WARN_ON_ONCE(in_nmi())) > + return false; > + > + /* In kernel FPU usage already active? */ > + if (this_cpu_read(in_kernel_fpu)) > + return false; > + > + /* > + * When not in NMI or hard interrupt context, FPU can be used:
"... can be used in:"
> + * > + * - Task context is safe except from within fpregs_lock()'ed > + * critical regions. > + * > + * - Soft interrupt processing context which cannot happen > + * while in a fpregs_lock()'ed critical region.
But those are only nitpicks. With those fixed:
Reviewed-by: Borislav Petkov <bp@suse.de>
Thx.
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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