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 49A6EC4332F for ; Wed, 30 Mar 2022 14:58:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347631AbiC3O7s (ORCPT ); Wed, 30 Mar 2022 10:59:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53230 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347217AbiC3O7m (ORCPT ); Wed, 30 Mar 2022 10:59:42 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E0F466406; Wed, 30 Mar 2022 07:57:53 -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 1C719615E7; Wed, 30 Mar 2022 14:57:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2F800C340EC; Wed, 30 Mar 2022 14:57:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1648652272; bh=0ohAXybc8U6+eIxqZN8sbhR7Ie+atDMwd4Z+q/8cZrQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qOdNWakpz/tB38GgP8O5A5OkgxV+edpaqvyeXZJRKovfi9gcnM/Sfq2ktTdITpTa/ AQKIdOXnQZW1SDESCygsZIEf86+xzsvfPN8GyAV5xPw70T1r8bTccgC2f9coijHJKr ZxvejzJKpznFwR+YPK/1Z24OvNTjZR1AAqsTfG2iQTTqt9Wzgyj5PP8Be4NbcSwGS4 yNqunFW8MvG9dFtpXpe3TY1IurDIV78e9EL5ULfPbAGGyWRRCfHgJrZf9KWVqDUgCf 7gVgHwd/LiXwi8gQsKHP+d8hePHK9ZAiDZpMcG/c5+8QZTqh/DT6QKd8PtNU6/H3tY jqHyp9RIRiEbg== Date: Wed, 30 Mar 2022 17:56:51 +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: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 30, 2022 at 05:54:18PM +0300, Jarkko Sakkinen wrote: > 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. How you organize TCS and stack is completely unrelated topic. BR, Jarkko