Re: [PATCH v3 5/5] x86/entry/64: Bypass enter_from_user_mode on non-context-tracking boots

From	Frederic Weisbecker <fweisbec@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v3 5/5] x86/entry/64: Bypass enter_from_user_mode on non-context-tracking boots
Date	2015-11-13 16:30 +0100
Message-ID	<quosy-88l-9@gated-at.bofh.it> (permalink)
References	<qu78l-5oc-3@gated-at.bofh.it> <qu78l-5oc-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Thu, Nov 12, 2015 at 12:59:04PM -0800, Andy Lutomirski wrote:
> On CONFIG_CONTEXT_TRACKING kernels that have context tracking
> disabled at runtime (which includes most distro kernels), we still
> have the overhead of a call to enter_from_user_mode in interrupt and
> exception entries.
> 
> If jump labels are available, this uses the jump label
> infrastructure to skip the call.

Looks good. But why are we still calling context tracking code on IRQs at all?

Thanks.
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[PATCH v3 5/5] x86/entry/64: Bypass enter_from_user_mode on non-context-tracking boots Andy Lutomirski <luto@kernel.org> - 2015-11-12 22:00 +0100
  Re: [PATCH v3 5/5] x86/entry/64: Bypass enter_from_user_mode on  non-context-tracking boots Thomas Gleixner <tglx@linutronix.de> - 2015-11-13 15:30 +0100
  Re: [PATCH v3 5/5] x86/entry/64: Bypass enter_from_user_mode on  non-context-tracking boots Frederic Weisbecker <fweisbec@gmail.com> - 2015-11-13 16:30 +0100

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