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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 10EFEC48BDF for ; Tue, 15 Jun 2021 07:11:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E597761417 for ; Tue, 15 Jun 2021 07:11:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230236AbhFOHNL (ORCPT ); Tue, 15 Jun 2021 03:13:11 -0400 Received: from pegase1.c-s.fr ([93.17.236.30]:45422 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229781AbhFOHNE (ORCPT ); Tue, 15 Jun 2021 03:13:04 -0400 Received: from localhost (mailhub3.si.c-s.fr [192.168.12.233]) by localhost (Postfix) with ESMTP id 4G3zxZ6l8PzB9cj; Tue, 15 Jun 2021 09:10:58 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id xd2TKTQK8ov2; Tue, 15 Jun 2021 09:10:58 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 4G3zxZ5qcLzB9VY; Tue, 15 Jun 2021 09:10:58 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 9B8BD8B7A5; Tue, 15 Jun 2021 09:10:58 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id Tr_kw5KW1-Uj; Tue, 15 Jun 2021 09:10:58 +0200 (CEST) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 1C5F38B7A3; Tue, 15 Jun 2021 09:10:58 +0200 (CEST) Subject: Re: [PATCH 6/7] powerpc/uaccess: Add unsafe_clear_user() To: Christoph Hellwig Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org References: <67eedb69ca81e5a4b16459a4c61f99e64cb42675.1623739212.git.christophe.leroy@csgroup.eu> From: Christophe Leroy Message-ID: <1940d0cc-1aea-07d0-95e6-8d63047e4d9e@csgroup.eu> Date: Tue, 15 Jun 2021 09:10:53 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 15/06/2021 à 08:53, Christoph Hellwig a écrit : > On Tue, Jun 15, 2021 at 06:41:02AM +0000, Christophe Leroy wrote: >> Implement unsafe_clear_user() for powerpc. >> It's a copy/paste of unsafe_copy_to_user() with value 0 as source. >> >> It may be improved in a later patch by using 'dcbz' instruction >> to zeroize full cache lines at once. > > Please add this to common code insted of making it powerpc specific. > A common version is added in previous patch. Just like unsafe_copy_to_user(), unsafe_clear_user() needs to be arch defined. unsafe_copy_to_user() has both an x86 implementation and a powerpc implementation, why do different ? I can't see how it could be not powerpc specific. At the end we want to use 'dcbz' to zeroize full cachelines at once, even if at the time being that's a simple write of 0.