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=-4.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 9B0FFC4727C for ; Wed, 30 Sep 2020 15:28:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5A21C2071E for ; Wed, 30 Sep 2020 15:28:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728232AbgI3P2P (ORCPT ); Wed, 30 Sep 2020 11:28:15 -0400 Received: from mga01.intel.com ([192.55.52.88]:56321 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728340AbgI3P2N (ORCPT ); Wed, 30 Sep 2020 11:28:13 -0400 IronPort-SDR: k9Hm1PcNCtCfg9m6MNxH31ArA38/mxaCkbc2BI5JjO0yW7kh6pZDrLjQCuGSy3W77Trhr7EGhe Sn6z713fscjQ== X-IronPort-AV: E=McAfee;i="6000,8403,9759"; a="180634704" X-IronPort-AV: E=Sophos;i="5.77,322,1596524400"; d="scan'208";a="180634704" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Sep 2020 08:28:11 -0700 IronPort-SDR: g+ftN8bg2AVIKSLrGl3QFGDC3k5p3Hse+SVFX9tE9Koi7BB+lVgEzEk8Fov7MFslm2TALtLEPC X9QcYRbFOgzg== X-IronPort-AV: E=Sophos;i="5.77,322,1596524400"; d="scan'208";a="498009790" Received: from geigerri-mobl.ger.corp.intel.com (HELO localhost) ([10.249.35.47]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Sep 2020 08:28:08 -0700 Date: Wed, 30 Sep 2020 18:28:06 +0300 From: Jarkko Sakkinen To: Dave Hansen Cc: linux-sgx@vger.kernel.org, x86@kernel.org, Haitao Huang , Sean Christopherson , Andrew Cooper , Borislav Petkov , Dave Hansen , Andy Lutomirski , Cedric Xing Subject: Re: [PATCH] x86/vdso: Remove retpoline from SGX vDSO call Message-ID: <20200930152806.GA52739@linux.intel.com> References: <20200930140108.48075-1-jarkko.sakkinen@linux.intel.com> <92578646-83a4-606c-b251-4d80cb62399c@intel.com> <20200930142017.GA49393@linux.intel.com> <112ad81e-16ab-d6e0-09e7-3658874434f7@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <112ad81e-16ab-d6e0-09e7-3658874434f7@intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org On Wed, Sep 30, 2020 at 07:33:38AM -0700, Dave Hansen wrote: > On 9/30/20 7:20 AM, Jarkko Sakkinen wrote: > > I'm not expert on Spectre, or any sort of security researcher, but I've > > read a few papers about and understand the general concept. With the > > constraints how the callback is used in practice, I'd *guess* it is > > fine to drop retpoline but I really need some feedback on this from > > people who understand these attacks better. > > Do you recall why you added it in the first place? What was the > motivation for it? Were you responding to a review comment? Absolutely cannot recall it :-) I even cannot recall the exact time when we landed the vDSO in the first place. Too much stuff has happend during the long three year upstreaming cycle. I will try to backtrack this info. /Jarkko