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 X-Spam-Level: X-Spam-Status: No, score=-7.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5CF56C10F27 for ; Mon, 9 Mar 2020 08:37:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3C9112072A for ; Mon, 9 Mar 2020 08:37:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726820AbgCIIhj (ORCPT ); Mon, 9 Mar 2020 04:37:39 -0400 Received: from mga18.intel.com ([134.134.136.126]:59851 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726071AbgCIIhi (ORCPT ); Mon, 9 Mar 2020 04:37:38 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 09 Mar 2020 01:37:37 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,532,1574150400"; d="scan'208";a="230853650" Received: from shao2-debian.sh.intel.com (HELO [10.239.13.3]) ([10.239.13.3]) by orsmga007.jf.intel.com with ESMTP; 09 Mar 2020 01:37:36 -0700 Subject: Re: [kbuild-all] Re: arch/x86/mm/fault.o: warning: objtool: do_page_fault()+0x4fb: unreachable instruction To: Frederic Weisbecker , kbuild test robot Cc: kbuild-all@lists.01.org, linux-kernel@vger.kernel.org, Ingo Molnar References: <202003061843.YVzsDc3A%lkp@intel.com> <20200306142732.GA8590@lenoir> From: Rong Chen Message-ID: Date: Mon, 9 Mar 2020 16:37:24 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20200306142732.GA8590@lenoir> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/6/20 10:27 PM, Frederic Weisbecker wrote: > On Fri, Mar 06, 2020 at 06:48:47PM +0800, kbuild test robot wrote: >> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master >> head: 9f65ed5fe41ce08ed1cb1f6a950f9ec694c142ad >> commit: ee6352b2c47a24234398e06381edd93a8e965976 x86/context-tracking: Remove exception_enter/exit() from do_page_fault() >> date: 8 weeks ago >> config: x86_64-randconfig-a002-20200306 (attached as .config) >> compiler: gcc-4.9 (Debian 4.9.2-10+deb8u1) 4.9.2 >> reproduce: >> git checkout ee6352b2c47a24234398e06381edd93a8e965976 >> # save the attached .config to linux build tree >> make ARCH=x86_64 >> >> If you fix the issue, kindly add following tag >> Reported-by: kbuild test robot >> >> All warnings (new ones prefixed by >>): >> >>>> arch/x86/mm/fault.o: warning: objtool: do_page_fault()+0x4fb: unreachable instruction > I tried several versions of gcc and I can't reproduce the warning. Also looking > at the code I fail to find an actual unreachable path. Do you still have the vmlinux around? > > Hi Frederic, Sorry for the inconvenience, we checked again and only found this issue on gcc-4.9.2, and there's no issue on gcc-4.9.3 or other new versions. Best Regards, Rong Chen