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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 8A95EC742A4 for ; Thu, 11 Jul 2019 19:51:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 677B820863 for ; Thu, 11 Jul 2019 19:51:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728992AbfGKTvQ (ORCPT ); Thu, 11 Jul 2019 15:51:16 -0400 Received: from mga02.intel.com ([134.134.136.20]:43133 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726116AbfGKTvP (ORCPT ); Thu, 11 Jul 2019 15:51:15 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Jul 2019 12:51:15 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.63,479,1557212400"; d="scan'208";a="168731247" Received: from bxing-desk.ccr.corp.intel.com (HELO [134.134.148.187]) ([134.134.148.187]) by orsmga003.jf.intel.com with ESMTP; 11 Jul 2019 12:51:15 -0700 Subject: Re: [RFC PATCH v2 0/3] An alternative __vdso_sgx_enter_enclave() to allow enclave/host parameter passing using untrusted stack To: Jarkko Sakkinen Cc: linux-kernel@vger.kernel.org, linux-sgx@vger.kernel.org, akpm@linux-foundation.org, dave.hansen@intel.com, sean.j.christopherson@intel.com, serge.ayoun@intel.com, shay.katz-zamir@intel.com, haitao.huang@intel.com, kai.svahn@intel.com, kai.huang@intel.com References: <20190424062623.4345-1-cedric.xing@intel.com> <20190710111719.nnoedfo4wvbfghq7@linux.intel.com> <686e47d2-f45c-6828-39d1-48374925de6c@intel.com> <20190710224628.epjxwlpqqxdurmzo@linux.intel.com> <20190710231538.dkc7tyeyvns53737@linux.intel.com> <27cf0fc7-71c6-7dc1-f031-86bf887f1fe1@intel.com> <20190711093809.4ogxe25laeoyp4ve@linux.intel.com> From: "Xing, Cedric" Message-ID: <7774fb16-7e41-f504-f3c8-d2588859be48@intel.com> Date: Thu, 11 Jul 2019 12:51:13 -0700 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190711093809.4ogxe25laeoyp4ve@linux.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/11/2019 2:38 AM, Jarkko Sakkinen wrote: > On Wed, Jul 10, 2019 at 04:37:41PM -0700, Xing, Cedric wrote: >> On 7/10/2019 4:15 PM, Jarkko Sakkinen wrote: >>> On Thu, Jul 11, 2019 at 01:46:28AM +0300, Jarkko Sakkinen wrote: >>>> On Wed, Jul 10, 2019 at 11:08:37AM -0700, Xing, Cedric wrote: >>>>>> With these conclusions I think the current vDSO API is sufficient for >>>>>> Linux. >>>>> >>>>> The new vDSO API is to support data exchange on stack. It has nothing to do >>>>> with debugging. BTW, the community has closed on this. >>>> >>>> And how that is useful? >>>> >>>>> The CFI directives are for stack unwinding. They don't affect what the code >>>>> does so you can just treat them as NOPs if you don't understand what they >>>>> do. However, they are useful to not only debuggers but also exception >>>>> handling code. libunwind also has a setjmp()/longjmp() implementation based >>>>> on CFI directives. >>>> >>>> Of course I won't merge code of which usefulness I don't understand. >>> >>> I re-read the cover letter [1] because it usually is the place >>> to "pitch" a feature. >>> >>> It fails to address two things: >>> >>> 1. How and in what circumstances is an untrusted stack is a better >>> vessel for handling exceptions than the register based approach >>> that we already have? >> >> We are not judging which vessel is better (or the best) among all possible >> vessels. We are trying to enable more vessels. Every vessel has its pros and >> cons so there's *no* single best vessel. > > I think reasonable metric is actually the coverage of the Intel SDK > based enclaves. How widely are they in the wild? If the user base is > large, it should be reasonable to support this just based on that. I don't know how many existing enclaves out there, but definitely larger than 0 (zero), while user base for the old API is definitely 0. What are you worrying, really? > /Jarkko >