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 0E48BC18E5B for ; Mon, 16 Mar 2020 22:55:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E2F67205ED for ; Mon, 16 Mar 2020 22:55:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732881AbgCPWzf (ORCPT ); Mon, 16 Mar 2020 18:55:35 -0400 Received: from mga04.intel.com ([192.55.52.120]:11589 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732846AbgCPWzf (ORCPT ); Mon, 16 Mar 2020 18:55:35 -0400 IronPort-SDR: 7WkIFmFQF6Bml4R2d5RXaEdz3L9peyCD/CXyAoOIb59qfznmoAzz+biS7hlzTlWWWXQ0aPuBzJ K40W8rDf6Vqw== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Mar 2020 15:55:34 -0700 IronPort-SDR: L2UZYp09IyTg9lHguWJOyfhxMETseoQhwxC5xJdF+NWb9h4rfOEvdD0BM+3RuV3M9BjueC4pVG TqG09vv7uGLA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,561,1574150400"; d="scan'208";a="267744344" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.202]) by fmsmga004.fm.intel.com with ESMTP; 16 Mar 2020 15:55:34 -0700 Date: Mon, 16 Mar 2020 15:55:34 -0700 From: Sean Christopherson To: Jethro Beekman Cc: Nathaniel McCallum , Jarkko Sakkinen , linux-kernel@vger.kernel.org, x86@kernel.org, linux-sgx@vger.kernel.org, akpm@linux-foundation.org, dave.hansen@intel.com, Neil Horman , "Huang, Haitao" , andriy.shevchenko@linux.intel.com, tglx@linutronix.de, "Svahn, Kai" , bp@alien8.de, Josh Triplett , luto@kernel.org, kai.huang@intel.com, David Rientjes , cedric.xing@intel.com, Patrick Uiterwijk , Andy Lutomirski , Connor Kuehl , Harald Hoyer , Lily Sturmann Subject: Re: [PATCH v28 21/22] x86/vdso: Implement a vDSO for Intel SGX enclave call Message-ID: <20200316225534.GK24267@linux.intel.com> References: <20200303233609.713348-1-jarkko.sakkinen@linux.intel.com> <20200303233609.713348-22-jarkko.sakkinen@linux.intel.com> <20200315012523.GC208715@linux.intel.com> <7f9f2efe-e9af-44da-6719-040600f5b351@fortanix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7f9f2efe-e9af-44da-6719-040600f5b351@fortanix.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 16, 2020 at 02:31:36PM +0100, Jethro Beekman wrote: > Can someone remind me why we're not passing TCS in RBX but on the stack? I finally remembered why. It's pulled off the stack and passed into the exit handler. I'm pretty sure the vDSO could take it in %rbx and manually save it on the stack, but I'd rather keep the current behavior so that the vDSO is callable from C (assuming @leaf is changed to be passed via %rcx).