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From: Frederic Weisbecker <fweisbec@gmail.com>
To: Andy Lutomirski <luto@kernel.org>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
	Brian Gerst <brgerst@gmail.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Borislav Petkov <bp@alien8.de>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v3 5/5] x86/entry/64: Bypass enter_from_user_mode on non-context-tracking boots
Date: Fri, 13 Nov 2015 16:26:13 +0100	[thread overview]
Message-ID: <20151113152612.GA14397@lerouge> (raw)
In-Reply-To: <73ee804fff48cd8c66b65b724f9f728a11a8c686.1447361906.git.luto@kernel.org>

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.

  parent reply	other threads:[~2015-11-13 15:26 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-12 20:58 [PATCH v3 0/5] x86 entry stuff, maybe for 4.4 Andy Lutomirski
2015-11-12 20:59 ` [PATCH v3 1/5] x86/entry/64: Fix irqflag tracing wrt context tracking Andy Lutomirski
2015-11-24  9:35   ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2015-11-12 20:59 ` [PATCH v3 2/5] context_tracking: Switch to new static_branch API Andy Lutomirski
2015-11-24  9:35   ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2015-11-12 20:59 ` [PATCH v3 3/5] x86/asm: Error out if asm/jump_label.h is included inappropriately Andy Lutomirski
2015-11-13 14:13   ` Thomas Gleixner
2015-11-24  9:35   ` [tip:x86/asm] x86/asm: Error out if asm/ jump_label.h " tip-bot for Andy Lutomirski
2015-11-12 20:59 ` [PATCH v3 4/5] x86/asm: Add asm macros for static keys/jump labels Andy Lutomirski
2015-11-13 14:22   ` Thomas Gleixner
2015-11-24  9:36   ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2015-11-12 20:59 ` [PATCH v3 5/5] x86/entry/64: Bypass enter_from_user_mode on non-context-tracking boots Andy Lutomirski
2015-11-13 14:23   ` Thomas Gleixner
2015-11-13 15:26   ` Frederic Weisbecker [this message]
2015-11-16 19:10     ` Andy Lutomirski
2015-11-16 22:50       ` Frederic Weisbecker
2015-11-16 23:57         ` Andy Lutomirski
2015-11-19  0:57           ` Frederic Weisbecker
2015-11-24  9:36   ` [tip:x86/asm] " tip-bot for Andy Lutomirski

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