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=-3.8 required=3.0 tests=BAYES_00, 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 8841BC433E2 for ; Fri, 11 Sep 2020 08:57:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 53113221EB for ; Fri, 11 Sep 2020 08:57:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725613AbgIKI5e (ORCPT ); Fri, 11 Sep 2020 04:57:34 -0400 Received: from mga12.intel.com ([192.55.52.136]:6078 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725778AbgIKI51 (ORCPT ); Fri, 11 Sep 2020 04:57:27 -0400 IronPort-SDR: 03vgo1ud2kOf+HTtbV5CtEhCoLi5RubfyfL64dnhczHNA5P0ehqcn4TCJhBtp000bXXFSGBQhJ xUNR0Fkfiq1w== X-IronPort-AV: E=McAfee;i="6000,8403,9740"; a="138237407" X-IronPort-AV: E=Sophos;i="5.76,414,1592895600"; d="scan'208";a="138237407" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Sep 2020 01:57:26 -0700 IronPort-SDR: STzB4Z1f5k2Y17Kt6dqGvJ1/8TEUcasYpfdzYzf78CBHv0EzFQOGXNqFSOLaS/nQPn7BbHUO0I r35mZQkMgRHQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.76,414,1592895600"; d="scan'208";a="334451946" Received: from smile.fi.intel.com (HELO smile) ([10.237.68.40]) by orsmga008.jf.intel.com with ESMTP; 11 Sep 2020 01:57:24 -0700 Received: from andy by smile with local (Exim 4.94) (envelope-from ) id 1kGeSc-00Fu75-04; Fri, 11 Sep 2020 11:31:10 +0300 Date: Fri, 11 Sep 2020 11:31:09 +0300 From: Andy Shevchenko To: Kent Gibson Cc: Linus Walleij , Bartosz Golaszewski , linux-gpio@vger.kernel.org, Arnd Bergmann Subject: Re: [PATCH v1 1/2] gpiolib: Fix line event handling in syscall compatible mode Message-ID: <20200911083109.GF1891694@smile.fi.intel.com> References: <20200910101935.47140-1-andriy.shevchenko@linux.intel.com> <20200911030539.GA574097@sol> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200911030539.GA574097@sol> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Sender: linux-gpio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org On Fri, Sep 11, 2020 at 11:05:39AM +0800, Kent Gibson wrote: > On Thu, Sep 10, 2020 at 01:19:34PM +0300, Andy Shevchenko wrote: > > The introduced line even handling ABI in the commit > > > > s/even/event/ > > > 61f922db7221 ("gpio: userspace ABI for reading GPIO line events") > > > > missed the fact that 64-bit kernel may serve for 32-bit applications. > > In such case the very first check in the lineevent_read() will fail > > due to alignment differences. > > > > To workaround this introduce lineeven_to_user() helper which returns actual > > size of the structure and copies its content to user if asked. > > > > And again here. Thanks! ... > > +#ifdef __x86_64__ > > + /* i386 has no padding after 'id' */ > > + if (in_ia32_syscall()) { > > + struct compat_ge { > > + compat_u64 timestamp __packed; > > + u32 id; > > + } cge; > > + > > + if (buf && ge) { > > + cge = (struct compat_ge){ ge->timestamp, ge->id }; > > + if (copy_to_user(buf, &cge, sizeof(cge))) > > + return -EFAULT; > > + } > > + > > + return sizeof(cge); > > + } > > +#endif > > + > > + if (buf && ge) { > > + if (copy_to_user(buf, ge, sizeof(*ge))) > > + return -EFAULT; > > + } > > + > > + return sizeof(*ge); > > +} > > > > The dual-purpose nature of this function makes it more complicated than > it needs to be. > I was going to suggest splitting it into separate functions, but... > > Given that struct compat_ge is a strict truncation of struct > gpioevent_data, how about reducing this function to just determining the > size of the event for user space, say lineevent_user_size(), and > replacing sizeof(ge) with that calculcated size throughout > lineevent_read()? So you mean something like struct compat_gpioeevent_data { compat_u64 timestamp; u32 id; } __packed; #ifdef __x86_64__ /* i386 has no padding after 'id' */ size_t ge_size = in_ia32_syscall() ? sizeof(struct compat_gpioevent_data) : sizeof(struct gpioevent_data); #else size_t ge_size = sizeof(struct gpioevent_data) ; #endif ? ... > Is patch 2 in any way related to this patch? No. It can be applied separately. -- With Best Regards, Andy Shevchenko