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 EBE80C433F5 for ; Fri, 7 Oct 2022 18:50:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229506AbiJGSuY (ORCPT ); Fri, 7 Oct 2022 14:50:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57138 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229470AbiJGSuU (ORCPT ); Fri, 7 Oct 2022 14:50:20 -0400 Received: from mail.zytor.com (unknown [IPv6:2607:7c80:54:3::138]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B1687ABD60 for ; Fri, 7 Oct 2022 11:50:19 -0700 (PDT) Received: from [127.0.0.1] ([73.223.250.219]) (authenticated bits=0) by mail.zytor.com (8.17.1/8.17.1) with ESMTPSA id 297InvYN3880193 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Fri, 7 Oct 2022 11:49:57 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 297InvYN3880193 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2022090501; t=1665168598; bh=ebbXAFUQTJ5N3J/tbr1SoNx5sHiGAoFoQG3WsBx76IY=; h=Date:From:To:CC:Subject:In-Reply-To:References:From; b=M3kjoZp0i0uCERjjUEzlsByOKuCR0blDY3/kObrsY1y1+QiyogKmaF48oiGuoPMMM N5M1ppY9YackhvRvtXhgx/bT5h80YLUeq90w/V58QnIs+j/UEknc0NP++3dqlaTO+Q s6/cs8FSwxU17aFb8zHmSK5RFfbhFOtCwrKc5s2ZeORtDQW68cgazXv6NOH639fudm w3hzJ24nETePB2Hbc1plqCN5vU/bW5dALCkFyzXJAD/H0DkDAjQ7cIkyFgpCVjxIW/ vEtdJUa6//w/0iW6RhqzYJfhY/i34qFPd6GGXWJVxGz3FU1oY2nVLRVVWKlFUyyCyB 7eSAjxPIUC3RQ== Date: Fri, 07 Oct 2022 11:49:54 -0700 From: "H. Peter Anvin" To: "Li, Xin3" , Peter Zijlstra CC: "linux-kernel@vger.kernel.org" , "x86@kernel.org" , "tglx@linutronix.de" , "mingo@redhat.com" , "bp@alien8.de" , "dave.hansen@linux.intel.com" Subject: =?US-ASCII?Q?RE=3A_=5BPATCH_6/6=5D_x86/gsseg=3A_use_the_LKGS_in?= =?US-ASCII?Q?struction_if_available_for_load=5Fgs=5Findex=28=29?= User-Agent: K-9 Mail for Android In-Reply-To: References: <20221006154041.13001-1-xin3.li@intel.com> <20221006154041.13001-7-xin3.li@intel.com> <5E3D5429-33BC-4924-B82C-C731507C0F06@zytor.com> Message-ID: <3F0DCCD0-2179-47E2-BC57-A948C0C91098@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On October 7, 2022 11:07:34 AM PDT, "Li, Xin3" wrot= e: >> >> + alternative_io("1: call asm_load_gs_index\n" >> >> + "=2Epushsection \"=2Efixup\",\"ax\"\n" >> >> + "2: xorl %k[sel], %k[sel]\n" >> >> + " jmp 1b\n" >> >> + "=2Epopsection\n" >> >> + _ASM_EXTABLE(1b, 2b), >> >> + _ASM_BYTES(0x3e) LKGS_DI, >> >> + X86_FEATURE_LKGS, >> >> + ASM_OUTPUT2([sel] "+D" (sel), ASM_CALL_CONSTRAINT), >> >> + ASM_NO_INPUT_CLOBBER(_ASM_AX)); >> >> } >> > >> >I'm very sure none of this was tested=2E=2E=2E the =2Efixup section ha= sn't >> >existed for almost a year now=2E >> > >> > e5eefda5aa51 ("x86: Remove =2Efixup section") >>=20 >> Xin, what did you use as the forward-porting baseline? > >6=2E0 release, and my kernel dump shows me a fixup section is there, and = a fixup section is created anyway if we do "pushsection "\=2Efixup\""=2E > > > Yeah=2E =2Efixup is really Just Another Text Section =E2=84=A2, so it is p= robably not surprising if it has crept back in=2E