From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH v2 3/4] input: Deprecate real timestamps beyond year 2106 Date: Fri, 28 Oct 2016 23:47:39 +0200 Message-ID: <3544660.FKrMrRAIUC@wuerfel> References: <1476761253-13450-1-git-send-email-deepa.kernel@gmail.com> <1960434.J8MW3Y2VCi@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: Received: from mout.kundenserver.de ([217.72.192.73]:63244 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756113AbcJ1Vrn (ORCPT ); Fri, 28 Oct 2016 17:47:43 -0400 In-Reply-To: Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Deepa Dinamani Cc: Dmitry Torokhov , linux-input@vger.kernel.org, Linux Kernel Mailing List , y2038 Mailman List On Friday, October 28, 2016 2:39:35 PM CEST Deepa Dinamani wrote: > >> >> @@ -55,24 +60,24 @@ struct ff_effect_compat { > >> >> > >> >> static inline size_t input_event_size(void) > >> >> { > >> >> - return (in_compat_syscall() && !COMPAT_USE_64BIT_TIME) ? > >> >> - sizeof(struct input_event_compat) : sizeof(struct input_event); > >> >> + return in_compat_syscall() ? sizeof(struct raw_input_event_compat) : > >> >> + sizeof(struct raw_input_event); > >> >> } > >> > > >> > I think the COMPAT_USE_64BIT_TIME check has to stay here, > >> > it's needed for x32 mode on x86-64. > >> > >> There is no time_t anymore in the raw_input_event structure. > >> The struct uses __kernel_ulong_t type. > >> This should take care of x32 support. > > > > I don't think it does. > > > >> From this cover letter: > >> https://www.spinics.net/lists/linux-arch/msg16356.html > >> > >> I see that that the __kernel types were introduced to address the ABI > >> issues for x32. > > > > This is a variation of the problem we are trying to solve for > > the other architectures in your patch set: > > > > On x32, the kernel uses produces a structure with the 64-bit > > layout, using __u64 tv_sec, to match the current user space > > that has 64-bit __kernel_ulong_t and 64-bit time_t, but > > in_compat_syscall() also returns 'true' here, as this is > > mostly a 32-bit ABI (time_t being one of the exceptions). > > Yes, I missed this. > > in_compat_syscall() is true for x32, this would mean we end up here > even if it is a x32 syscall. > But, wouldn't it be better to use in_x32_syscall() here since there is > no timeval any more? We have to distinguish four cases on x86: - native 32-bit, input_event with 32-bit time_t - compat 32-bit, input_event_compat with 32-bit time_t - native 64-bit, input_event with 64-bit time_t - compat x32, input_event with 64-bit time_t The first three can happen on other architectures too, the last one is x86 specific. There are probably other ways to express the condition above, but I can't think of one that is better than the one we have today. Arnd