Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932699AbbKMOYQ (ORCPT ); Fri, 13 Nov 2015 09:24:16 -0500 Received: from www.linutronix.de ([62.245.132.108]:60083 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932330AbbKMOYN (ORCPT ); Fri, 13 Nov 2015 09:24:13 -0500 Date: Fri, 13 Nov 2015 09:23:25 -0500 (EST) From: Thomas Gleixner To: Andy Lutomirski cc: x86@kernel.org, linux-kernel@vger.kernel.org, Brian Gerst , Linus Torvalds , Borislav Petkov , =?ISO-8859-15?Q?Fr=E9d=E9ric_Weisbecker?= , Peter Zijlstra Subject: Re: [PATCH v3 5/5] x86/entry/64: Bypass enter_from_user_mode on non-context-tracking boots In-Reply-To: <73ee804fff48cd8c66b65b724f9f728a11a8c686.1447361906.git.luto@kernel.org> Message-ID: References: <73ee804fff48cd8c66b65b724f9f728a11a8c686.1447361906.git.luto@kernel.org> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001,URIBL_BLOCKED=0.001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 714 Lines: 17 On Thu, 12 Nov 2015, 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. > > Signed-off-by: Andy Lutomirski Reviewed-by: Thomas Gleixner -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/