Received: by 2002:ac0:a5a7:0:0:0:0:0 with SMTP id m36-v6csp5756426imm; Mon, 23 Jul 2018 05:39:47 -0700 (PDT) X-Google-Smtp-Source: AAOMgpdW0ioHDAroMGDas/xzjWJUcmAhLIAQJ8fHAX8D/ZpQvsw0L63cqLi9ZUBNiFypaP/G86YO X-Received: by 2002:a17:902:8c84:: with SMTP id t4-v6mr12995767plo.100.1532349587104; Mon, 23 Jul 2018 05:39:47 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1532349587; cv=none; d=google.com; s=arc-20160816; b=jy3KHan0UU+NUpioj2p2dJRYvLQP5F976vurk1mxg38DYrVFu194EIku6QI4YBBbZs C6zrTKhmN2Gerjwb4GNPkNHwCUsT1KWFUN8cYO2gCfZ1s4bCBVj5RL2ZM9UBlcT2cGqL S5yEfnI05lb/Z1mX868+n0MzAYCAkWomzqsgbozZBEdVDfLgGTrZBMR3vH6PjPqQXo7M k1E8d8VzILqLEco2vXeNDShppQjlO9ZVPZhG5AK3Xld4VtAiWdkK3u15FCYmfL7uXhKt t0r0JpAfcCDDkv/SpvYMnFZY4475c32LAXp+9Y2ypxcs41xq53BDOX1RSooD2fcNGTIW huZg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding :content-language:in-reply-to:mime-version:user-agent:date :message-id:autocrypt:openpgp:from:cc:references:to:subject :arc-authentication-results; bh=ppGdtn8kP5H6VIteM3hDj2QclPG8UKFJ9JruRjWKWhM=; b=t5loqZqdoR4ucDv2cZYbHAmry0zgSXr5ul0cU5tYsFvoIvnYs9LP7KcdTRCrGHGAUA hnwgile3CbNrrebx10jmDvEgfOfXHDqRw3jf8ZpV3DYvNbnstiQtYIzdzfemp5GI3nWD zWqy+k+58Jnp3RjGzFdR54VqOhN/Gvz0sWgaeER6jfRNq4u9qL/hPb4ju8MdqEi0k0tf 4gVyxTP50ahOozLbhiGaDsmO4jWgmrrUoXrvJwh2j5CQaBAqRH9c+LglMpCp/noPGRk+ yOMHYJ+57fPypc8jyOi4f9jj5SSsf68c2J7Fu2TO1LAevoh5j+OHZvUPOHj15jSjhpcO Lviw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id 65-v6si7662012pgi.195.2018.07.23.05.39.32; Mon, 23 Jul 2018 05:39:47 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388545AbeGWNjb (ORCPT + 99 others); Mon, 23 Jul 2018 09:39:31 -0400 Received: from mga02.intel.com ([134.134.136.20]:37026 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388022AbeGWNjb (ORCPT ); Mon, 23 Jul 2018 09:39:31 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 23 Jul 2018 05:38:29 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,393,1526367600"; d="scan'208";a="218295837" Received: from sssawant-mobl1.amr.corp.intel.com (HELO [10.252.132.170]) ([10.252.132.170]) by orsmga004.jf.intel.com with ESMTP; 23 Jul 2018 05:38:29 -0700 Subject: Re: [RFC 1/2] x86/entry/64: Use the TSS sp2 slot for rsp_scratch To: Andy Lutomirski , x86@kernel.org, LKML References: <38b5a24f3c9f519dd7dc98171eb3a3c669fff48c.1532281180.git.luto@kernel.org> Cc: Borislav Petkov , Linus Torvalds From: Dave Hansen Openpgp: preference=signencrypt Autocrypt: addr=dave.hansen@linux.intel.com; keydata= xsFNBE6HMP0BEADIMA3XYkQfF3dwHlj58Yjsc4E5y5G67cfbt8dvaUq2fx1lR0K9h1bOI6fC oAiUXvGAOxPDsB/P6UEOISPpLl5IuYsSwAeZGkdQ5g6m1xq7AlDJQZddhr/1DC/nMVa/2BoY 2UnKuZuSBu7lgOE193+7Uks3416N2hTkyKUSNkduyoZ9F5twiBhxPJwPtn/wnch6n5RsoXsb ygOEDxLEsSk/7eyFycjE+btUtAWZtx+HseyaGfqkZK0Z9bT1lsaHecmB203xShwCPT49Blxz VOab8668QpaEOdLGhtvrVYVK7x4skyT3nGWcgDCl5/Vp3TWA4K+IofwvXzX2ON/Mj7aQwf5W iC+3nWC7q0uxKwwsddJ0Nu+dpA/UORQWa1NiAftEoSpk5+nUUi0WE+5DRm0H+TXKBWMGNCFn c6+EKg5zQaa8KqymHcOrSXNPmzJuXvDQ8uj2J8XuzCZfK4uy1+YdIr0yyEMI7mdh4KX50LO1 pmowEqDh7dLShTOif/7UtQYrzYq9cPnjU2ZW4qd5Qz2joSGTG9eCXLz5PRe5SqHxv6ljk8mb ApNuY7bOXO/A7T2j5RwXIlcmssqIjBcxsRRoIbpCwWWGjkYjzYCjgsNFL6rt4OL11OUF37wL QcTl7fbCGv53KfKPdYD5hcbguLKi/aCccJK18ZwNjFhqr4MliQARAQABzShEYXZpZCBDaHJp c3RvcGhlciBIYW5zZW4gPGRhdmVAc3I3MS5uZXQ+wsF7BBMBAgAlAhsDBgsJCAcDAgYVCAIJ CgsEFgIDAQIeAQIXgAUCTo3k0QIZAQAKCRBoNZUwcMmSsMO2D/421Xg8pimb9mPzM5N7khT0 2MCnaGssU1T59YPE25kYdx2HntwdO0JA27Wn9xx5zYijOe6B21ufrvsyv42auCO85+oFJWfE K2R/IpLle09GDx5tcEmMAHX6KSxpHmGuJmUPibHVbfep2aCh9lKaDqQR07gXXWK5/yU1Dx0r VVFRaHTasp9fZ9AmY4K9/BSA3VkQ8v3OrxNty3OdsrmTTzO91YszpdbjjEFZK53zXy6tUD2d e1i0kBBS6NLAAsqEtneplz88T/v7MpLmpY30N9gQU3QyRC50jJ7LU9RazMjUQY1WohVsR56d ORqFxS8ChhyJs7BI34vQusYHDTp6PnZHUppb9WIzjeWlC7Jc8lSBDlEWodmqQQgp5+6AfhTD kDv1a+W5+ncq+Uo63WHRiCPuyt4di4/0zo28RVcjtzlGBZtmz2EIC3vUfmoZbO/Gn6EKbYAn rzz3iU/JWV8DwQ+sZSGu0HmvYMt6t5SmqWQo/hyHtA7uF5Wxtu1lCgolSQw4t49ZuOyOnQi5 f8R3nE7lpVCSF1TT+h8kMvFPv3VG7KunyjHr3sEptYxQs4VRxqeirSuyBv1TyxT+LdTm6j4a mulOWf+YtFRAgIYyyN5YOepDEBv4LUM8Tz98lZiNMlFyRMNrsLV6Pv6SxhrMxbT6TNVS5D+6 UorTLotDZKp5+M7BTQRUY85qARAAsgMW71BIXRgxjYNCYQ3Xs8k3TfAvQRbHccky50h99TUY sqdULbsb3KhmY29raw1bgmyM0a4DGS1YKN7qazCDsdQlxIJp9t2YYdBKXVRzPCCsfWe1dK/q 66UVhRPP8EGZ4CmFYuPTxqGY+dGRInxCeap/xzbKdvmPm01Iw3YFjAE4PQ4hTMr/H76KoDbD cq62U50oKC83ca/PRRh2QqEqACvIH4BR7jueAZSPEDnzwxvVgzyeuhwqHY05QRK/wsKuhq7s UuYtmN92Fasbxbw2tbVLZfoidklikvZAmotg0dwcFTjSRGEg0Gr3p/xBzJWNavFZZ95Rj7Et db0lCt0HDSY5q4GMR+SrFbH+jzUY/ZqfGdZCBqo0cdPPp58krVgtIGR+ja2Mkva6ah94/oQN lnCOw3udS+Eb/aRcM6detZr7XOngvxsWolBrhwTQFT9D2NH6ryAuvKd6yyAFt3/e7r+HHtkU kOy27D7IpjngqP+b4EumELI/NxPgIqT69PQmo9IZaI/oRaKorYnDaZrMXViqDrFdD37XELwQ gmLoSm2VfbOYY7fap/AhPOgOYOSqg3/Nxcapv71yoBzRRxOc4FxmZ65mn+q3rEM27yRztBW9 AnCKIc66T2i92HqXCw6AgoBJRjBkI3QnEkPgohQkZdAb8o9WGVKpfmZKbYBo4pEAEQEAAcLB XwQYAQIACQUCVGPOagIbDAAKCRBoNZUwcMmSsJeCEACCh7P/aaOLKWQxcnw47p4phIVR6pVL e4IEdR7Jf7ZL00s3vKSNT+nRqdl1ugJx9Ymsp8kXKMk9GSfmZpuMQB9c6io1qZc6nW/3TtvK pNGz7KPPtaDzvKA4S5tfrWPnDr7n15AU5vsIZvgMjU42gkbemkjJwP0B1RkifIK60yQqAAlT YZ14P0dIPdIPIlfEPiAWcg5BtLQU4Wg3cNQdpWrCJ1E3m/RIlXy/2Y3YOVVohfSy+4kvvYU3 lXUdPb04UPw4VWwjcVZPg7cgR7Izion61bGHqVqURgSALt2yvHl7cr68NYoFkzbNsGsye9ft M9ozM23JSgMkRylPSXTeh5JIK9pz2+etco3AfLCKtaRVysjvpysukmWMTrx8QnI5Nn5MOlJj 1Ov4/50JY9pXzgIDVSrgy6LYSMc4vKZ3QfCY7ipLRORyalFDF3j5AGCMRENJjHPD6O7bl3Xo 4DzMID+8eucbXxKiNEbs21IqBZbbKdY1GkcEGTE7AnkA3Y6YB7I/j9mQ3hCgm5muJuhM/2Fr OPsw5tV/LmQ5GXH0JQ/TZXWygyRFyyI2FqNTx4WHqUn3yFj8rwTAU1tluRUYyeLy0ayUlKBH ybj0N71vWO936MqP6haFERzuPAIpxj2ezwu0xb1GjTk4ynna6h5GjnKgdfOWoRtoWndMZxbA z5cecg== Message-ID: <854ac759-efec-3e35-59a9-8da35b2b5156@linux.intel.com> Date: Mon, 23 Jul 2018 05:38:27 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <38b5a24f3c9f519dd7dc98171eb3a3c669fff48c.1532281180.git.luto@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/22/2018 10:45 AM, Andy Lutomirski wrote: > + /* > + * sp2 is scratch space used by the SYSCALL64 handler. Linux does > + * not use rung 2, so sp2 is not otherwise needed. > + */ > u64 sp2; Could we call out the actual thing that we use this slot for, and the symbol name so folks can find the corresponding code that does this? While I know the spot in entry_64 you're talking about, it might not be patently obvious to everyone, and it's also a bit more challenging to grep for than normal C code. Maybe: /* * Since Linux does not use ring 2, the 'sp2' slot is unused. * entry_SYSCALL_64 uses this as scratch space to stash the user * %RSP value. */