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=-2.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT autolearn=unavailable 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 3DC3CC61CE8 for ; Sat, 19 Jan 2019 14:29:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F03D121738 for ; Sat, 19 Jan 2019 14:29:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="NR2Et1dr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728211AbfASO30 (ORCPT ); Sat, 19 Jan 2019 09:29:26 -0500 Received: from pandora.armlinux.org.uk ([78.32.30.218]:46256 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728154AbfASO3Z (ORCPT ); Sat, 19 Jan 2019 09:29:25 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2014; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=d63QEDmnrldHslsD9mf7nQ3yGthqTGS5pzxH/xWmhF0=; b=NR2Et1druix8/4pNwnuT+RILu 9d1Rxv6XWz1TN+9FqQ/p/P7acLs7c7trws/Jg8fG3MPHsJWvYLs9TlllAhF873aPPG/2SMtV0ge2K NorzWF9puUKyS/b5Aid7zX6nzfqByLov3FnZBmN2/p8vSFlBK8+rFnheOM8d1SGvO/EXM=; Received: from e5254000004ec.dyn.armlinux.org.uk ([2002:4e20:1eda:1:5054:ff:fe00:4ec]:35354 helo=shell.armlinux.org.uk) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1gkrcD-0006gO-Mk; Sat, 19 Jan 2019 14:28:53 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.89) (envelope-from ) id 1gkrcC-0002s2-N7; Sat, 19 Jan 2019 14:28:52 +0000 Date: Sat, 19 Jan 2019 14:28:52 +0000 From: Russell King - ARM Linux admin To: Andy Lutomirski Cc: Arnd Bergmann , y2038 Mailman List , Linux API , LKML , linux-arch , Matt Turner , Catalin Marinas , Will Deacon , Tony Luck , Fenghua Yu , Geert Uytterhoeven , Michal Simek , Paul Burton , Helge Deller , Benjamin Herrenschmidt , Michael Ellerman , Martin Schwidefsky , Heiko Carstens , Rich Felker , "David S. Miller" , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , X86 ML , Max Filippov , Andrew Morton , Deepa Dinamani , "Eric W. Biederman" , Firoz Khan , alpha , linux-arm-kernel , linux-ia64@vger.kernel.org, linux-m68k , linux-mips@vger.kernel.org, Parisc List , linuxppc-dev , linux-s390 , Linux-sh list , sparclinux , Network Development , Linux FS Devel Subject: Re: [PATCH v2 29/29] y2038: add 64-bit time_t syscalls to all 32-bit architectures Message-ID: <20190119142852.cntdihah4mpa3lgx@e5254000004ec.dyn.armlinux.org.uk> References: <20190118161835.2259170-1-arnd@arndb.de> <20190118161835.2259170-30-arnd@arndb.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org On Fri, Jan 18, 2019 at 11:53:25AM -0800, Andy Lutomirski wrote: > On Fri, Jan 18, 2019 at 11:33 AM Arnd Bergmann wrote: > > > > On Fri, Jan 18, 2019 at 7:50 PM Andy Lutomirski wrote: > > > On Fri, Jan 18, 2019 at 8:25 AM Arnd Bergmann wrote: > > > > - Once we get to 512, we clash with the x32 numbers (unless > > > > we remove x32 support first), and probably have to skip > > > > a few more. I also considered using the 512..547 space > > > > for 32-bit-only calls (which never clash with x32), but > > > > that also seems to add a bit of complexity. > > > > > > I have a patch that I'll send soon to make x32 use its own table. As > > > far as I'm concerned, 547 is *it*. 548 is just a normal number and is > > > not special. But let's please not reuse 512..547 for other purposes > > > on x86 variants -- that way lies even more confusion, IMO. > > > > Fair enough, the space for those numbers is cheap enough here. > > I take it you mean we also should not reuse that number space if > > we were to decide to remove x32 soon, but you are not worried > > about clashing with arch/alpha when everything else uses consistent > > numbers? > > > > I think we have two issues if we reuse those numbers for new syscalls. > First, I'd really like to see new syscalls be numbered consistently > everywhere, or at least on all x86 variants, and we can't on x32 > because they mean something else. Perhaps more importantly, due to > what is arguably a rather severe bug, issuing a native x86_64 syscall > (x32 bit clear) with nr in the range 512..547 does *not* return > -ENOSYS on a kernel with x32 enabled. Instead it does something that > is somewhat arbitrary. With my patch applied, it will return -ENOSYS, > but old kernels will still exist, and this will break syscall probing. > > Can we perhaps just start the consistent numbers above 547 or maybe > block out 512..547 in the new regime? I don't think you gain much with that kind of scheme - it won't take very long before an architecture misses having a syscall added, and then someone else adds their own. Been there with ARM - I was keeping the syscall table in the same order as x86 for new syscalls, but now that others have been adding syscalls to the table since I converted ARM to the tabular form, that's now gone out the window. So, I think it's completely pointless to do what you're suggesting. We'll just end up with a big hole in the middle of the syscall table and then revert back to random numbering of syscalls thereafter again. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up