From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752155AbdBYUaG (ORCPT ); Sat, 25 Feb 2017 15:30:06 -0500 Received: from mail.skyhub.de ([5.9.137.197]:46892 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751968AbdBYUaF (ORCPT ); Sat, 25 Feb 2017 15:30:05 -0500 Date: Sat, 25 Feb 2017 21:29:02 +0100 From: Borislav Petkov To: hpa@zytor.com Cc: Peter Zijlstra , Ingo Molnar , Arjan van de Ven , Thomas Gleixner , linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, jpoimboe@redhat.com, richard.weinberger@gmail.com, Andrew Morton Subject: Re: [PATCH] x86: Implement __WARN using UD0 Message-ID: <20170225202902.roif2sxdvronwbsl@pd.tnic> References: <20170224074325.GA4095@gmail.com> <20170224083115.GK6515@twins.programming.kicks-ass.net> <20170224091537.GA18182@gmail.com> <21ac6e53-2fcd-52e9-e72d-9faf7da14d1e@zytor.com> <20170224104133.GO6515@twins.programming.kicks-ass.net> <20170225103808.wufwhne3aozqi2nd@pd.tnic> <20170225193844.bwmumbtvlfdgmm67@pd.tnic> <95C4FAB6-FB6B-4985-9844-7A9E58D69843@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <95C4FAB6-FB6B-4985-9844-7A9E58D69843@zytor.com> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Feb 25, 2017 at 12:04:18PM -0800, hpa@zytor.com wrote: > Note that once you have a trap you can create an immediate yourself, > the CPU doesn't need to do it for you, unless you really care about > latency (reading the instruction steam can be kind of expensive, > although it is quite a bit simpler if we know we come from kernel > space.) You mean, put it after the INT 9 opcode? CD 09 immed8 Yeah, that could be one way to pass callsite-specific info, if needed. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.