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 14D04C433EF for ; Wed, 30 Mar 2022 14:55:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347600AbiC3O5L (ORCPT ); Wed, 30 Mar 2022 10:57:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42778 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347567AbiC3O5E (ORCPT ); Wed, 30 Mar 2022 10:57:04 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E01124925A; Wed, 30 Mar 2022 07:55:16 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 774E96097C; Wed, 30 Mar 2022 14:55:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 63E91C340EC; Wed, 30 Mar 2022 14:55:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1648652115; bh=I+yJk0OAWbSGqwnxt70vNBRoJxFYe+GVrXI+LY7+JQ8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=XHDr0Bv1y+gtIMF36FJE/RlvVVR3GpNLnf4Te7RHach2xV6WCgDhZjupJ9bCFwSHj NJXMax2wgDt2Evna03tIBlaqDvT44j219GN9+5mEIqOnBsVjabCH0JLOC9vk6nObnY ifAkXfPYZT8cU6veasvCWt6pAntlMRKCJKNTtvu//nUaHvZR8YhG8pOw5Bh7/4NQma e6b0uwyluHx0DqfFjQtjaHn4P11uc+DI9QpBM0SR2ks7Vp+HWlQkI+1ahf2/SFpjXh /qQDmYkQrbozmATqqOygKTJJ+wM4mifYVCspp+9Yhohz3SEHk0HHbWtt+tNT079we7 HCtzLz5b1571w== Date: Wed, 30 Mar 2022 17:54:14 +0300 From: Jarkko Sakkinen To: Reinette Chatre Cc: Shuah Khan , Dave Hansen , Shuah Khan , "open list:INTEL SGX" , "open list:KERNEL SELFTEST FRAMEWORK" , open list Subject: Re: [PATCH v2 1/2] selftests/sgx: Use rip relative addressing for encl_stack Message-ID: References: <20220322074313.7444-1-jarkko@kernel.org> <7b7732ec-c7ff-cf92-510f-64c83ed985cd@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7b7732ec-c7ff-cf92-510f-64c83ed985cd@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 28, 2022 at 02:49:04PM -0700, Reinette Chatre wrote: > Hi Jarkko, > > On 3/22/2022 12:43 AM, Jarkko Sakkinen wrote: > > Simplify the test_encl_bootstrap.S flow by using rip-relative addressing. > > Compiler does the right thing here, and this removes dependency on where > > TCS entries need to be located in the binary, i.e. allows the binary layout > > changed freely in the future. > > > > Cc: Reinette Chatre > > Cc: Dave Hansen > > Signed-off-by: Jarkko Sakkinen > > --- > > tools/testing/selftests/sgx/test_encl_bootstrap.S | 6 +----- > > 1 file changed, 1 insertion(+), 5 deletions(-) > > > > diff --git a/tools/testing/selftests/sgx/test_encl_bootstrap.S b/tools/testing/selftests/sgx/test_encl_bootstrap.S > > index 82fb0dfcbd23..1c1b5c6c4ffe 100644 > > --- a/tools/testing/selftests/sgx/test_encl_bootstrap.S > > +++ b/tools/testing/selftests/sgx/test_encl_bootstrap.S > > @@ -40,11 +40,7 @@ > > .text > > > > encl_entry: > > - # RBX contains the base address for TCS, which is the first address > > - # inside the enclave for TCS #1 and one page into the enclave for > > - # TCS #2. By adding the value of encl_stack to it, we get > > - # the absolute address for the stack. > > - lea (encl_stack)(%rbx), %rax > > + lea (encl_stack)(%rip), %rax > > xchg %rsp, %rax > > push %rax > > > > The goal of the above snippet is to set RSP to ensure that each thread has its own stack. > > Since EENTER computes RIP as EnclaveBase + TCS.OENTRY, by using offset from RIP this > would result in all TCS with OENTRY of encl_entry to use the same stack, no? > > Could you please consider the following as an alternative: > https://lore.kernel.org/lkml/65c137c875bd4da675eaba35316ff43d7cfd52f8.1644274683.git.reinette.chatre@intel.com/ > > The idea in that patch is that a new TCS would always need to be accompanied by a > dedicated stack so, at least for testing purposes, the TCS and stack can be dynamically > allocated together with the TCS page following its stack. This seems much simpler > to me and also makes the following patch unnecessary. There's no better alternative than use rip. Compiler will fix it up. So, no, I won't consider that. This a dead obvious change. BR, Jarkko