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 C15BEC433DB for ; Sat, 19 Sep 2020 23:24:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 92FE02311B for ; Sat, 19 Sep 2020 23:24:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726759AbgISXYU (ORCPT ); Sat, 19 Sep 2020 19:24:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49962 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726680AbgISXYU (ORCPT ); Sat, 19 Sep 2020 19:24:20 -0400 Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [IPv6:2002:c35c:fd02::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AFFE7C0613CE; Sat, 19 Sep 2020 16:24:19 -0700 (PDT) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kJmDD-0020kM-6N; Sat, 19 Sep 2020 23:24:11 +0000 Date: Sun, 20 Sep 2020 00:24:11 +0100 From: Al Viro To: Andy Lutomirski Cc: Christoph Hellwig , Andrew Morton , Jens Axboe , Arnd Bergmann , David Howells , linux-arm-kernel@lists.infradead.org, x86@kernel.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, io-uring@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, keyrings@vger.kernel.org, linux-security-module@vger.kernel.org Subject: Re: [PATCH 1/9] kernel: add a PF_FORCE_COMPAT flag Message-ID: <20200919232411.GK3421308@ZenIV.linux.org.uk> References: <20200919224122.GJ3421308@ZenIV.linux.org.uk> <36CF3DE7-7B4B-41FD-9818-FDF8A5B440FB@amacapital.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <36CF3DE7-7B4B-41FD-9818-FDF8A5B440FB@amacapital.net> Sender: Al Viro Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Sat, Sep 19, 2020 at 03:53:40PM -0700, Andy Lutomirski wrote: > > It would not be a win - most of the syscalls don't give a damn > > about 32bit vs. 64bit... > > Any reasonable implementation would optimize it out for syscalls that don’t care. Or it could be explicit: > > DEFINE_MULTIARCH_SYSCALL(...) 1) what would that look like? 2) have you counted the syscalls that do and do not need that? 3) how many of those realistically *can* be unified with their compat counterparts? [hint: ioctl(2) cannot]