From: Julien Grall <julien.grall@arm.com>
To: Dave Martin <Dave.Martin@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: Mon, 24 Jun 2019 17:44:53 +0100 [thread overview]
Message-ID: <54e5e484-0268-0593-e5e7-16d7451cc849@arm.com> (raw)
In-Reply-To: <20190621153316.GC2790@e103592.cambridge.arm.com>
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,
--
Julien Grall
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next prev parent reply other threads:[~2019-06-24 16:45 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 [this message]
2019-06-25 9:41 ` Dave Martin
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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