Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932680AbbKMOXp (ORCPT ); Fri, 13 Nov 2015 09:23:45 -0500 Received: from www.linutronix.de ([62.245.132.108]:60070 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932115AbbKMOXn (ORCPT ); Fri, 13 Nov 2015 09:23:43 -0500 Date: Fri, 13 Nov 2015 09:22:57 -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 4/5] x86/asm: Add asm macros for static keys/jump labels In-Reply-To: <63aa45c4b692e8469e1876d6ccbb5da707972990.1447361906.git.luto@kernel.org> Message-ID: References: <63aa45c4b692e8469e1876d6ccbb5da707972990.1447361906.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: 987 Lines: 25 On Thu, 12 Nov 2015, Andy Lutomirski wrote: > Unfortunately, we can only do this if HAVE_JUMP_LABEL. In principle, we > could do some serious surgery on the core jump label infrastructure > to keep the patch infrastructure available on x86 on all builds, but > that's probably not worth it. > > Implementing the macros using a conditional branch as a fallback > seems like a bad idea: we'd have to clobber flags. > > This limitation can't cause silent failures -- trying to include > asm/jump_label.h at all on a non-HAVE_JUMP_LABEL kernel will error > out. The macro's users are responsible for handling this issue > themselves. > > 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/