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 86229C742A4 for ; Thu, 11 Jul 2019 19:49:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6163E20863 for ; Thu, 11 Jul 2019 19:49:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728975AbfGKTtH (ORCPT ); Thu, 11 Jul 2019 15:49:07 -0400 Received: from mga11.intel.com ([192.55.52.93]:39776 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726116AbfGKTtG (ORCPT ); Thu, 11 Jul 2019 15:49:06 -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 fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Jul 2019 12:49:06 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.63,479,1557212400"; d="scan'208";a="168730721" 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 12:49:06 -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> <20190711093621.4wstj7bc7w6wxxj2@linux.intel.com> From: "Xing, Cedric" Message-ID: Date: Thu, 11 Jul 2019 12:49:04 -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: <20190711093621.4wstj7bc7w6wxxj2@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 2:36 AM, Jarkko Sakkinen wrote: > On Wed, Jul 10, 2019 at 03:54:20PM -0700, Xing, Cedric wrote: >> On 7/10/2019 3:46 PM, 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? >> >> There is a lengthy discussion on its usefulness so I don't want to repeat. >> In short, it allows using untrusted stack as a convenient method to exchange >> data with the enclave. It is currently being used by Intel's SGX SDK for >> e/o-calls parameters. >> >>>> 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. >> >> Sure. >> >> Any other questions I can help with? > > I dissected my concerns in other email. We can merge this feature after > v21 if it makes sense. Sent out v3 of vDSO changes last night. I hope your concerns have been properly addressed. The new vDSO API is a community consensus. I can help on whatever technical problems you may have but I don't see a reason you should reject it. > /Jarkko >