Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754727AbbKMP0R (ORCPT ); Fri, 13 Nov 2015 10:26:17 -0500 Received: from mail-wm0-f44.google.com ([74.125.82.44]:36448 "EHLO mail-wm0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754225AbbKMP0Q (ORCPT ); Fri, 13 Nov 2015 10:26:16 -0500 Date: Fri, 13 Nov 2015 16:26:13 +0100 From: Frederic Weisbecker To: Andy Lutomirski Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Brian Gerst , Linus Torvalds , Borislav Petkov , Peter Zijlstra Subject: Re: [PATCH v3 5/5] x86/entry/64: Bypass enter_from_user_mode on non-context-tracking boots Message-ID: <20151113152612.GA14397@lerouge> References: <73ee804fff48cd8c66b65b724f9f728a11a8c686.1447361906.git.luto@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <73ee804fff48cd8c66b65b724f9f728a11a8c686.1447361906.git.luto@kernel.org> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 719 Lines: 17 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. -- 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/