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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 7BB96C2D0DB for ; Thu, 23 Jan 2020 13:30:45 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 358E021835 for ; Thu, 23 Jan 2020 13:30:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 358E021835 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 483NSf4d2WzDqPM for ; Fri, 24 Jan 2020 00:30:42 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=intel.com (client-ip=134.134.136.24; helo=mga09.intel.com; envelope-from=jani.nikula@intel.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.intel.com Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 483N2Q1Zy2zDqP0 for ; Fri, 24 Jan 2020 00:11:18 +1100 (AEDT) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 23 Jan 2020 05:11:13 -0800 X-IronPort-AV: E=Sophos;i="5.70,354,1574150400"; d="scan'208";a="220660992" Received: from jnikula-mobl3.fi.intel.com (HELO localhost) ([10.237.66.161]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 23 Jan 2020 05:11:08 -0800 From: Jani Nikula To: Christophe Leroy , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Linus Torvalds , Alexander Viro , Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" Subject: Re: [PATCH v3 2/7] uaccess: Tell user_access_begin() if it's for a write or not In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: Date: Thu, 23 Jan 2020 15:11:05 +0200 Message-ID: <8736c6e2s6.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: x86@kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, 23 Jan 2020, Christophe Leroy wrote: > On 32 bits powerPC (book3s/32), only write accesses to user are > protected and there is no point spending time on unlocking for reads. > > On 64 bits powerpc (book3s/64 at least), access can be granted > read only, write only or read/write. > > Add an argument to user_access_begin() to tell when it's for write and > return an opaque key that will be used by user_access_end() to know > what was done by user_access_begin(). IMHO an opaque key is a prime example of a case where the use of an opaque typedef is warranted. Nobody needs to know or care it's specifically an unsigned long. BR, Jani. -- Jani Nikula, Intel Open Source Graphics Center