From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751290AbdBWOhS (ORCPT ); Thu, 23 Feb 2017 09:37:18 -0500 Received: from merlin.infradead.org ([205.233.59.134]:46524 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751098AbdBWOhR (ORCPT ); Thu, 23 Feb 2017 09:37:17 -0500 Date: Thu, 23 Feb 2017 15:36:44 +0100 From: Peter Zijlstra To: Josh Poimboeuf Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, arjan@linux.intel.com, bp@alien8.de, richard.weinberger@gmail.com Subject: Re: [PATCH] x86: Implement __WARN using UD0 Message-ID: <20170223143644.GD6515@twins.programming.kicks-ass.net> References: <20170223132813.GB6515@twins.programming.kicks-ass.net> <20170223141232.nr6fahyhcljravbn@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170223141232.nr6fahyhcljravbn@treble> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 23, 2017 at 08:12:32AM -0600, Josh Poimboeuf wrote: > On Thu, Feb 23, 2017 at 02:28:13PM +0100, Peter Zijlstra wrote: > > +/* > > + * Only UD2 is defined in the Intel SDM and AMD64 docs, > > + * but the interweb provided UD0 and UD1: > > + * > > + * https://groups.google.com/forum/#!topic/alt.os.assembly/_rS4L0fnqGE > > FYI, the latest Intel SDM does have UD0 and UD1. Ooh, shiny, a new one. > > + * Since various instruction decoders disagree on the length of UD1, > > + * we cannot use it either. So use UD0 for WARN. > > It shows up as "(bad)" in objtool and gdb, though it still gets the > length right: > > 8b9: 0f ff (bad) > > It would be nice if the tools knew about it... Now that the SDM lists them, I suppose that's going to be any day now :-)