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 7230FC4332F for ; Tue, 18 Oct 2022 22:41:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229926AbiJRWlw (ORCPT ); Tue, 18 Oct 2022 18:41:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49636 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229889AbiJRWlu (ORCPT ); Tue, 18 Oct 2022 18:41:50 -0400 Received: from mga06.intel.com (mga06b.intel.com [134.134.136.31]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 71D27AF1BE for ; Tue, 18 Oct 2022 15:41:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1666132907; x=1697668907; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=43nga7sHlYGp/WXO1HBW7Mr8hHzUz0ck5JawD+SCfMg=; b=IAG9nqqi7IRLDZeCA/Fsl6+rMaMVVdxCDrbOxmvvNzGzyu+Kzv1kk5KA 01L0lbqAaJJGMcvD8kjGrL8TqMuHdnWe+4KBisj+MxJ8k5ROyFq854Ptd hLe/dndv1FZ37KqHmId8u/Sqf9vSh+0MWtGtb60DqWPkgTrUqM9Yhtqqz nTGUSM8rUCkUJX/zkwSU7+DkqkLdXc8uFiHnhxNk3sld6pjOpihDywaU4 TeE/EdxN0B0hg7C6OaFqtOIZRwNm9mgd+Ooi749JnTzWIqkV+cRCir1hG 1qVv9MOFBJ2vUClakpDLrY7eZjMkwnjlZECdlH2JFMxlBlAepyhRW8tj6 g==; X-IronPort-AV: E=McAfee;i="6500,9779,10504"; a="368305154" X-IronPort-AV: E=Sophos;i="5.95,194,1661842800"; d="scan'208";a="368305154" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Oct 2022 15:41:46 -0700 X-IronPort-AV: E=McAfee;i="6500,9779,10504"; a="660032778" X-IronPort-AV: E=Sophos;i="5.95,194,1661842800"; d="scan'208";a="660032778" Received: from jjsopko-mobl.amr.corp.intel.com (HELO [10.213.163.40]) ([10.213.163.40]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Oct 2022 15:41:44 -0700 Message-ID: <35961c2f-08ab-9036-bc0c-6ede269ad3ec@intel.com> Date: Tue, 18 Oct 2022 15:41:43 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.2 Subject: Re: [PATCHv10 09/15] x86: Expose untagging mask in /proc/$PID/arch_status Content-Language: en-US To: "Kirill A. Shutemov" Cc: Dave Hansen , Andy Lutomirski , Peter Zijlstra , x86@kernel.org, Kostya Serebryany , Andrey Ryabinin , Andrey Konovalov , Alexander Potapenko , Taras Madan , Dmitry Vyukov , "H . J . Lu" , Andi Kleen , Rick Edgecombe , Bharata B Rao , Jacob Pan , Ashok Raj , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20221018113358.7833-1-kirill.shutemov@linux.intel.com> <20221018113358.7833-10-kirill.shutemov@linux.intel.com> <20221018222419.oy2z2wanvwp2pnrm@box.shutemov.name> From: Dave Hansen In-Reply-To: <20221018222419.oy2z2wanvwp2pnrm@box.shutemov.name> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/18/22 15:24, Kirill A. Shutemov wrote: > On Tue, Oct 18, 2022 at 02:02:43PM -0700, Dave Hansen wrote: >> On 10/18/22 04:33, Kirill A. Shutemov wrote: >>> Add a line in /proc/$PID/arch_status to report untag_mask. It can be >>> used to find out LAM status of the process from the outside. It is >>> useful for debuggers. >> Considering that address masking is not x86-specific, it seems like this >> needs a better home (another file in /proc). > In generic /proc/$PID/status? Seems like a sane place to me. > And I'm not sure if it is a good idea at this stage. Semantics around tags > is not settled across architectures: somewhere it is per-thread, somewhere > per-process, somewhere it is global. > > Maybe keep it arch-specific? Yeah, but all of those things could be served by a thread-specific ABI. The per-thread ABI won't enumerate the scope of the thing, of course. But, it _can_ precisely communicate what semantics the thread has.