From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0AC34C433EF for ; Mon, 4 Jul 2022 12:06:21 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4Lc4K75QrNz3f5V for ; Mon, 4 Jul 2022 22:06:19 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; secure) header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=casper.20170209 header.b=JLISIeys; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=infradead.org (client-ip=2001:8b0:10b:1236::1; helo=casper.infradead.org; envelope-from=peterz@infradead.org; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; secure) header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=casper.20170209 header.b=JLISIeys; dkim-atps=neutral Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4Lc4JS5kjZz302N for ; Mon, 4 Jul 2022 22:05:44 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=kIdu/42GiilHlXUS78N+LpZH4GE+kn27IfgICi3avuI=; b=JLISIeyssHb/kRbwBuaUKrdqYH G5DdMBv/BqSqZncpjaTbVoX38L7oDa11sj4yAPxb2R3yr+njxADtoXOt4Uan/9yV4pliVrM0ngTtf ojxNY8UJjAf+GKRq949ZvqIGE/kNuoXvZyub3BIGErUkR23tQVqyMOq9eVmcrp0qzQVQEtdRgy5Dk 8Gvx/WEn2J5yzDXRFUiBj7E8XV2COecDNWybtI9RILDTkFitzC2Mljhth9BvwA4/brUyCf514b1W3 0gmGaxFLtfix0Uia0G6HszjE0wODeG9AdiaRW6ymEKK8OXE6CQtEMEbLFyAqFqAIk9ZRp4oxkzpJX wZRtXUoQ==; Received: from dhcp-077-249-017-003.chello.nl ([77.249.17.3] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1o8Kpd-00HEp3-3O; Mon, 04 Jul 2022 12:05:37 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 9C83830033D; Mon, 4 Jul 2022 14:05:36 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 85D292028F029; Mon, 4 Jul 2022 14:05:36 +0200 (CEST) Date: Mon, 4 Jul 2022 14:05:36 +0200 From: Peter Zijlstra To: Christophe Leroy Subject: Re: [RFC PATCH v3 11/12] powerpc: Remove unreachable() from WARN_ON() Message-ID: References: <20220624183238.388144-1-sv@linux.ibm.com> <20220624183238.388144-12-sv@linux.ibm.com> <70b6d08d-aced-7f4e-b958-a3c7ae1a9319@csgroup.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <70b6d08d-aced-7f4e-b958-a3c7ae1a9319@csgroup.eu> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "aik@ozlabs.ru" , "linux-kernel@vger.kernel.org" , "rostedt@goodmis.org" , "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" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Sat, Jun 25, 2022 at 06:46:54AM +0000, Christophe Leroy wrote: > > > Le 24/06/2022 à 20:32, Sathvika Vasireddy a écrit : > > objtool is throwing *unannotated intra-function call* > > warnings with a few instructions that are marked > > unreachable. Remove unreachable() from WARN_ON() > > to fix these warnings, as the codegen remains same > > with and without unreachable() in WARN_ON(). > > Did you try the two exemples described in commit 1e688dd2a3d6 > ("powerpc/bug: Provide better flexibility to WARN_ON/__WARN_FLAGS() with > asm goto") ? > > Without your patch: > > 00000640 : > 640: 81 23 00 84 lwz r9,132(r3) > 644: 71 29 40 00 andi. r9,r9,16384 > 648: 40 82 00 0c bne 654 > 64c: 80 63 00 0c lwz r3,12(r3) > 650: 4e 80 00 20 blr > 654: 0f e0 00 00 twui r0,0 > > 00000658 : > 658: 2c 04 00 00 cmpwi r4,0 > 65c: 41 82 00 0c beq 668 > 660: 7c 63 23 96 divwu r3,r3,r4 > 664: 4e 80 00 20 blr > 668: 0f e0 00 00 twui r0,0 > 66c: 38 60 00 00 li r3,0 > 670: 4e 80 00 20 blr Per this construct you should do as x86 does and assume twui terminates control flow and explicitly annotate the WARN case. That is, given the fact that BUG as no instructions following it, you can't very well annotate that. Alternatively, you can teach objtool to look at __bug_table to distinguish these cases.