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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 B0A23C43460 for ; Wed, 19 May 2021 01:48:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9372961361 for ; Wed, 19 May 2021 01:48:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234065AbhESBt1 (ORCPT ); Tue, 18 May 2021 21:49:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38544 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233971AbhESBt1 (ORCPT ); Tue, 18 May 2021 21:49:27 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 72B5CC06175F; Tue, 18 May 2021 18:48:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: Content-Type:In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To: Subject:Sender:Reply-To:Content-ID:Content-Description; bh=2NwcBNostJy1Ke+4ILrE7WCRyqgaMhj8wvJw1tgBdXo=; b=laSVCrf7d+Qxh5EkMKjosGES0G pwteEKfSfPf+boXbf11edzGJsdOfTgLX975fIPlODt3QbaMum89GsXNakjQ/jIspflPU+xnqoCcJj u9FU/dZDAkBzcxDYcVqAapXTLoR1yeCyFavP287XE7qxcCVKQGEFTuzaQFG1BA2oJTfnBE2l+ke/+ fp8q0zMCYDSQfoCpqQY4RNSMWx7iBRM54kXgSjithDpNHEKTqAL2QAO0V+wu6TvlNwkDSM8rQSpFx yC/gv0FqcOn4aap92aUSrZbmQg1k4z9saOprvsBxhdj4mzPkHpyRXy9qze/5k1ZoxgcY81Ab7zO/p 8CR1x5wQ==; Received: from [2601:1c0:6280:3f0::7376] by bombadil.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1ljBJf-00F4IC-92; Wed, 19 May 2021 01:48:07 +0000 Subject: Re: Fwd: [EXTERNAL] Re: ioctl.c:undefined reference to `__get_user_bad' To: "Russell King (Oracle)" Cc: Steve French , CIFS , linux-fsdevel , LAK References: <202105110829.MHq04tJz-lkp@intel.com> <5b29fe73-7c95-0b9f-3154-c053fa94cb67@infradead.org> <20210518100306.GS12395@shell.armlinux.org.uk> From: Randy Dunlap Message-ID: Date: Tue, 18 May 2021 18:48:04 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 MIME-Version: 1.0 In-Reply-To: <20210518100306.GS12395@shell.armlinux.org.uk> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 5/18/21 3:03 AM, Russell King (Oracle) wrote: > On Mon, May 17, 2021 at 02:06:33PM -0700, Randy Dunlap wrote: >> [adding back linux-arm-kernel; what happened to it? ] That was about what I thought was Steve F. dropping LAK on his response email. > Nothing. I'm not interested in trying to do major disgusting > contortions to make get_user() work for 8-byte values. If someone > else wants to put the effort in and come up with an elegant solution > that doesn't add warnings over the rest of the kernel, that's fine. > > As far as I remember, everything in __get_user_err() relies on > __gu_val _not_ being 64-bit. If we use the same trick that we do > in __get_user_check(): > > __inttype(x) __gu_val = (x); > > then if get_user() is called with a 64-bit integer value and a > pointer-to-32-bit location to fetch from, we'd end up passing a > 64-bit integer into the __get_user_asm() which could access the > wrong 32-bit half of the value in BE mode. Similar issue with > 64-bit vs pointer-to-16-bit. Yes, trying to handle get_user() of size 8 bytes is quite messy. I have a few versions and they are all ugly and cause build warnings. So we are down to what bugzilla calls WONTFIX. I'm OK with that. Thanks. -- ~Randy