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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DF15FC43334 for ; Thu, 14 Jul 2022 08:46:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237407AbiGNIqR (ORCPT ); Thu, 14 Jul 2022 04:46:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42612 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237486AbiGNIqH (ORCPT ); Thu, 14 Jul 2022 04:46:07 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5FF8A402FA; Thu, 14 Jul 2022 01:46:04 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id D28DCB823C0; Thu, 14 Jul 2022 08:46:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 887C1C34114; Thu, 14 Jul 2022 08:46:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1657788361; bh=YvDXaxqtI1ZaBSWpwefeqgjLcPs3Jqvc4sIJBv80ws8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=RBlFHN9Mkp0dnvOPW0m8j+KUxMrvjgdrcd7Y8kOhQBEa+5PBoJ9F7gsLXixpwyrSl 032eMu3WtEC35FgcQu6tlKYhSeLPLU5f+dOAbz6tQHNkG7XaBWIAdOvYbtPvQF2Ids AmhfrzMs27LV4x6qnmxvFJMVVKVB6D/a0FjPyyWc= Date: Thu, 14 Jul 2022 10:45:57 +0200 From: Greg Kroah-Hartman To: Ben Hutchings Cc: kernel test robot , Peter Zijlstra , kbuild-all@lists.01.org, linux-kernel@vger.kernel.org, Borislav Petkov , Josh Poimboeuf , Thadeu Lima de Souza Cascardo , stable@vger.kernel.org Subject: Re: [linux-stable-rc:linux-5.10.y 7082/7120] arch/x86/kernel/head_64.o: warning: objtool: xen_hypercall_mmu_update(): can't find starting instruction Message-ID: References: <202207130531.SkRjrrn8-lkp@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 14, 2022 at 10:28:54AM +0200, Greg Kroah-Hartman wrote: > On Thu, Jul 14, 2022 at 08:49:09AM +0200, Greg Kroah-Hartman wrote: > > On Thu, Jul 14, 2022 at 12:50:16AM +0200, Ben Hutchings wrote: > > > On Wed, Jul 13, 2022 at 05:38:47AM +0800, kernel test robot wrote: > > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-5.10.y > > > > head: 53b881e19526bcc3e51d9668cab955c80dcf584c > > > > commit: 7575d3f3bbd1c68d6833b45d1b98ed182832bd44 [7082/7120] x86: Use return-thunk in asm code > > > > config: x86_64-rhel-8.3-syz (https://download.01.org/0day-ci/archive/20220713/202207130531.SkRjrrn8-lkp@intel.com/config) > > > > compiler: gcc-11 (Debian 11.3.0-3) 11.3.0 > > > > reproduce (this is a W=1 build): > > > > # https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/commit/?id=7575d3f3bbd1c68d6833b45d1b98ed182832bd44 > > > > git remote add linux-stable-rc https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git > > > > git fetch --no-tags linux-stable-rc linux-5.10.y > > > > git checkout 7575d3f3bbd1c68d6833b45d1b98ed182832bd44 > > > > # save the config file > > > > mkdir build_dir && cp config build_dir/.config > > > > make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash arch/x86/ > > > > > > > > If you fix the issue, kindly add following tag where applicable > > > > Reported-by: kernel test robot > > > > > > > > All warnings (new ones prefixed by >>): > > > > > > > > >> arch/x86/kernel/head_64.o: warning: objtool: xen_hypercall_mmu_update(): can't find starting instruction > > > > > > > > -- > > > > 0-DAY CI Kernel Test Service > > > > https://01.org/lkp > > > > > > Please add the following patch to fix this. This would also be > > > needed for 5.15-stable. > > > > > > Ben. > > > > > > From: Ben Hutchings > > > Date: Thu, 14 Jul 2022 00:39:33 +0200 > > > Subject: [PATCH] x86/xen: Fix initialisation in hypercall_page after rethunk > > > > > > The hypercall_page is special and the RETs there should not be changed > > > into rethunk calls (but can have SLS mitigation). Change the initial > > > instructions to ret + int3 padding, as was done in upstream commit > > > 5b2fc51576ef "x86/ibt,xen: Sprinkle the ENDBR". > > > > > > Signed-off-by: Ben Hutchings > > > --- > > > arch/x86/xen/xen-head.S | 4 ++-- > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S > > > index 38b73e7e54ba..2a3ef5fcba34 100644 > > > --- a/arch/x86/xen/xen-head.S > > > +++ b/arch/x86/xen/xen-head.S > > > @@ -69,9 +69,9 @@ SYM_CODE_END(asm_cpu_bringup_and_idle) > > > SYM_CODE_START(hypercall_page) > > > .rept (PAGE_SIZE / 32) > > > UNWIND_HINT_FUNC > > > - .skip 31, 0x90 > > > ANNOTATE_UNRET_SAFE > > > - RET > > > + ret > > > + .skip 31, 0xcc > > > .endr > > > > > > #define HYPERCALL(n) \ > > > > > > > > > > That's really odd, I swear I tried this myself: > > https://lore.kernel.org/r/Ys2jlGMqAe6+h1SX@kroah.com > > > > I'll go queue this up and see if that solves the issue on my side. But > > see Boris's comment about how this shouldn't be an issue in the end. > > Ah, yes, it does fix that warning, but causes this new one: > arch/x86/kernel/head_64.o: warning: objtool: .text+0x5: unreachable instruction > > I'll keep your patch here, as it makes sense, but it does just exchange > one warning for another one... Odd, I get the build warning when I build locally, but on my build server, that does this as a clean build, no warnings at all. Let's see what the build systems say... greg k-h