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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FROM,MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 C18CDC43387 for ; Fri, 21 Dec 2018 18:46:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8CDF521927 for ; Fri, 21 Dec 2018 18:46:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="WNItTatU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387636AbeLUSqz (ORCPT ); Fri, 21 Dec 2018 13:46:55 -0500 Received: from mail-lj1-f195.google.com ([209.85.208.195]:41442 "EHLO mail-lj1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730799AbeLUSqy (ORCPT ); Fri, 21 Dec 2018 13:46:54 -0500 Received: by mail-lj1-f195.google.com with SMTP id k15-v6so5598873ljc.8; Fri, 21 Dec 2018 10:46:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=9SN8LImLyDjwxI7cdHrCSZgKb9HBIBdcYlEOiHmK7PE=; b=WNItTatUbUjMWZLEJMMSg0/NRVug8/MNTSdPXEK9cohyLfkFrWkLV+J1+EA9ZSwWZR pL+zFN/R5toY+yIyorGQh8arn64pmvaVHUr1GPLLepfFief4pwZbUPm8KpqBBlFA8/ei TltGCNeZz+mY25hIcZjIkIbjzBhH1JRt/xuBVya24svLR+dxlw5JDz9zXpqGKbUuXRMV fom7J6vWysKI3ynEACs6aO6QJ1i5atpeXzeP6ru2kR90Xs8W70IgCXIPIwwdeGNMfe55 FI6YYe1J62ndW4Up3Np4x6t7iPXXQBZvvtYqToRDCDV+0sT2Jphcq3iDJZe+q/g4uuTq EeyA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=9SN8LImLyDjwxI7cdHrCSZgKb9HBIBdcYlEOiHmK7PE=; b=QcLECearp9Pl1xASsEebR3AHXKhxjTWCbIVyP8LG4f7e7l/ezVpoarcFXSSka4TYLS DpJlY+l/YwBdROIJQdG1Q4npwKFPFRCHzh5js3/HKOaAWLvm/XphBVORgDuM2+Gs8oEC cRHyMQcq32P09E41OiR+Beig5h3OIcG0sye54xHC6iQBoPXyNYQ5KTm3w2seDnVQyh/5 AmU8fBp4a4DIEV+yizIDP9bBU0R3elMBn/MZ9GSwq3Yi783FAT2GbEfhEhBc9ljwsQEn i/UbWdaWLLCCcOHQOVsmc8OOlQXhDAIRbYi3XweSSBNMvfTjQtes9XqANsqC3ekdC6qP y/sA== X-Gm-Message-State: AJcUukeNz1fckaT0qOpPS7oe67agFW91gwHNQ/P6718K4clNsTYtoYO0 dL112M6EexUfhK979/eURz9zDf/JHCs= X-Google-Smtp-Source: ALg8bN5A7ixJIaEhK+HJ1WGLkJa9Mb4Im59RfMZDB3PQ0GgyBMakdY9zgvZFwFwnBVwrExsYnyCnjA== X-Received: by 2002:a2e:81a:: with SMTP id 26-v6mr2530570lji.14.1545418012645; Fri, 21 Dec 2018 10:46:52 -0800 (PST) Received: from ?IPv6:2001:14bb:51:a4c8:5c24:24d7:ca5f:e7d2? (dmhwpt3bffxn8z3-j6k-4.rev.dnainternet.fi. [2001:14bb:51:a4c8:5c24:24d7:ca5f:e7d2]) by smtp.gmail.com with ESMTPSA id v5-v6sm4847827lje.78.2018.12.21.10.46.50 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 21 Dec 2018 10:46:51 -0800 (PST) Subject: Re: [PATCH 01/12] x86_64: memset_user() To: Matthew Wilcox Cc: Andy Lutomirski , Peter Zijlstra , Dave Hansen , Mimi Zohar , Thiago Jung Bauermann , igor.stoppa@huawei.com, Nadav Amit , Kees Cook , Ahmed Soliman , linux-integrity@vger.kernel.org, kernel-hardening@lists.openwall.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20181221181423.20455-1-igor.stoppa@huawei.com> <20181221181423.20455-2-igor.stoppa@huawei.com> <20181221182515.GF10600@bombadil.infradead.org> From: Igor Stoppa Message-ID: Date: Fri, 21 Dec 2018 20:46:48 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20181221182515.GF10600@bombadil.infradead.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On 21/12/2018 20:25, Matthew Wilcox wrote: > On Fri, Dec 21, 2018 at 08:14:12PM +0200, Igor Stoppa wrote: >> +unsigned long __memset_user(void __user *addr, int c, unsigned long size) >> +{ >> + long __d0; >> + unsigned long pattern = 0; >> + int i; >> + >> + for (i = 0; i < 8; i++) >> + pattern = (pattern << 8) | (0xFF & c); > > That's inefficient. > > pattern = (unsigned char)c; > pattern |= pattern << 8; > pattern |= pattern << 16; > pattern |= pattern << 32; ok, thank you -- igor