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[2620:137:e000::1:20]) by mx.google.com with ESMTP id mh9-20020a17090b4ac900b001e68b44501esi19248106pjb.5.2022.07.05.09.30.35; Tue, 05 Jul 2022 09:31:13 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232493AbiGEP5r (ORCPT + 99 others); Tue, 5 Jul 2022 11:57:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56200 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232288AbiGEP5p (ORCPT ); Tue, 5 Jul 2022 11:57:45 -0400 Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 0872E1164 for ; Tue, 5 Jul 2022 08:57:44 -0700 (PDT) Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 265Fmsn6029167; Tue, 5 Jul 2022 10:48:55 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 265FmqXx029161; Tue, 5 Jul 2022 10:48:52 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Tue, 5 Jul 2022 10:48:52 -0500 From: Segher Boessenkool To: Christophe Leroy Cc: Peter Zijlstra , Marc Zyngier , "aik@ozlabs.ru" , Sathvika Vasireddy , "linux-kernel@vger.kernel.org" , "rostedt@goodmis.org" , Chen Zhongjin , "mingo@redhat.com" , Sathvika Vasireddy , "jpoimboe@redhat.com" , "paulus@samba.org" , "naveen.n.rao@linux.vnet.ibm.com" , "mbenes@suse.cz" , "linuxppc-dev@lists.ozlabs.org" , Linux ARM Subject: Re: [RFC PATCH v3 11/12] powerpc: Remove unreachable() from WARN_ON() Message-ID: <20220705154852.GR25951@gate.crashing.org> References: <20220624183238.388144-1-sv@linux.ibm.com> <20220624183238.388144-12-sv@linux.ibm.com> <70b6d08d-aced-7f4e-b958-a3c7ae1a9319@csgroup.eu> <92eae2ef-f9b6-019a-5a8e-728cdd9bbbc0@linux.vnet.ibm.com> <6ab46ef2-6bbd-e758-a7ff-5f62fdf1ca96@csgroup.eu> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <6ab46ef2-6bbd-e758-a7ff-5f62fdf1ca96@csgroup.eu> User-Agent: Mutt/1.4.2.3i X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,SPF_HELO_PASS, SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 04, 2022 at 12:34:08PM +0000, Christophe Leroy wrote: > Le 04/07/2022 ? 13:45, Peter Zijlstra a ?crit?: > > I'm somewhat confused; how is an empty STT_FUNC a valid construct on > > Power? > > So am I. It is likely not a valid construct, but that's what GCC seems > to generate when you call annotate_unreachable(). It is a valid construct on (almost) all targets. If the user chooses to have executable code terminate in limbo, that is what the compiler will do (and this can result in a code symbol with size 0). Compare this to data symbols with no size, the situation is quite similar. Segher