From: Dave Martin <Dave.Martin@arm.com>
To: Julien Grall <julien.grall@arm.com>
Cc: Anton.Kirilov@arm.com, catalin.marinas@arm.com,
will.deacon@arm.com, oleg@redhat.com, zhang.lei@jp.fujitsu.com,
alex.bennee@linaro.org, linux-arm-kernel@lists.infradead.org,
Daniel.Kiss@arm.com
Subject: Re: [RFC PATCH v2 7/8] arm64/sve: Don't disable SVE on syscalls return
Date: Tue, 25 Jun 2019 10:41:51 +0100 [thread overview]
Message-ID: <20190625094150.GY2790@e103592.cambridge.arm.com> (raw)
In-Reply-To: <54e5e484-0268-0593-e5e7-16d7451cc849@arm.com>
On Mon, Jun 24, 2019 at 05:44:53PM +0100, Julien Grall wrote:
> Hi Dave,
>
> I will answer the rest of the e-mail separately.
>
> On 6/21/19 4:33 PM, Dave Martin wrote:
> >On Thu, Jun 13, 2019 at 05:16:55PM +0100, Julien Grall wrote:
> >>+ * state on context switch. The bit will be set again while
> >>+ * restoring/zeroing the registers.
> >> */
> >>- sve_user_disable();
> >>+ if (test_and_clear_thread_flag(TIF_SVE))
> >>+ set_thread_flag(TIF_SVE_NEEDS_FLUSH);
> >
> >Do we need to do this under local_bh_disable()? Does it matter?
> >
> >It looks to me like this is called when we still have interrupts
> >disabled, which is probably worth fixing. This may actually be a bug:
> >if kzalloc() causes us to sleep, we have the potential to trigger
> >sleeping-while-atomic splats.
>
> I am not sure to understand this. Which kzalloc do you refer to? Is it the
> one in sve_alloc?
>
> >
> >If you agree that's a bug, try to come up with a preliminary patch
> >that's suitable for stable.
> >
> >(I may have just misunderstood / misremembered something here.)
>
> Cheers,
It looks like I completely confused myself here.
For some reason I though this was part of the do_sve_acc() path, which
is nonsense. So please ignore that comment!
do_sve_acc() is indeed called with interrupts enabled.
Cheers
---Dave
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next prev parent reply other threads:[~2019-06-25 9:44 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-13 16:16 [RFC PATCH v2 0/8] arm64/sve: First steps towards optimizing syscalls Julien Grall
2019-06-13 16:16 ` [RFC PATCH v2 1/8] arm64/fpsimd: Update documentation of do_sve_acc Julien Grall
2019-06-13 16:19 ` Julien Grall
2019-06-21 15:32 ` Dave Martin
2019-06-13 16:16 ` [RFC PATCH v2 2/8] arm64/signal: Update the comment in preserve_sve_context Julien Grall
2019-06-21 15:32 ` Dave Martin
2019-06-13 16:16 ` [RFC PATCH v2 3/8] arm64/fpsimdmacros: Allow the macro "for" to be used in more cases Julien Grall
2019-06-21 15:32 ` Dave Martin
2019-06-24 16:10 ` Julien Grall
2019-06-25 9:35 ` Dave Martin
2019-06-13 16:16 ` [RFC PATCH v2 4/8] arm64/fpsimdmacros: Introduce a macro to update ZCR_EL1.LEN Julien Grall
2019-06-21 15:32 ` Dave Martin
2019-06-13 16:16 ` [RFC PATCH v2 5/8] arm64/sve: Implement an helper to flush SVE registers Julien Grall
2019-06-21 15:33 ` Dave Martin
2019-06-24 16:28 ` Julien Grall
2019-06-25 9:37 ` Dave Martin
2019-06-13 16:16 ` [RFC PATCH v2 6/8] arm64/sve: Implement an helper to load SVE registers from FPSIMD state Julien Grall
2019-06-21 15:33 ` Dave Martin
2019-06-24 16:29 ` Julien Grall
2019-06-13 16:16 ` [RFC PATCH v2 7/8] arm64/sve: Don't disable SVE on syscalls return Julien Grall
2019-06-21 15:33 ` Dave Martin
2019-06-24 16:44 ` Julien Grall
2019-06-25 9:41 ` Dave Martin [this message]
2019-07-04 14:15 ` Catalin Marinas
2019-08-02 11:06 ` Julien Grall
2019-06-13 16:16 ` [RFC PATCH v2 8/8] arm64/sve: Rework SVE trap access to use TIF_SVE_NEEDS_FLUSH Julien Grall
2019-06-21 15:33 ` Dave Martin
2019-06-21 15:32 ` [RFC PATCH v2 0/8] arm64/sve: First steps towards optimizing syscalls Dave Martin
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