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=-4.0 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_PASS autolearn=ham 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 948D5C43387 for ; Wed, 16 Jan 2019 15:25:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 63144205C9 for ; Wed, 16 Jan 2019 15:25:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="wHYQXziJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730958AbfAPPZ0 (ORCPT ); Wed, 16 Jan 2019 10:25:26 -0500 Received: from mail-it1-f196.google.com ([209.85.166.196]:55663 "EHLO mail-it1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390553AbfAPPZ0 (ORCPT ); Wed, 16 Jan 2019 10:25:26 -0500 Received: by mail-it1-f196.google.com with SMTP id m62so3510255ith.5 for ; Wed, 16 Jan 2019 07:25:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=D0E22Hby5Pao2cSGvZHIa8ii3artikW4blfeIIldMd0=; b=wHYQXziJUiAppRoIEXCWKPL7IlXBnex+9yVagODZ04l3qT8fRO/9BiwFa4sGCAH39G 4jJCc9chKodwfVxMRDFgzdshnpcP4HDmRZBPDzg15S84U2KfH5sIVNDxmwLXHDENlH25 dPd6BxDgDoguueyFDbWNzTkCCKZ/zOvbCagRXv3o691w1OUQG42SUUkhU5pUvBgqiZqQ yFhi6UG+9IzkSLN5o/ZTjC866PaaXHfrJ99MeZQT6fjNJa7czJm6PC7RbuVBdlJwQQAm lSjIHf3+UxStQWg2ySizCiILXtkVuME1Kb8B2VrC3ehkdKvPrs+ardjqbQyZW/HRgXqT JpFg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=D0E22Hby5Pao2cSGvZHIa8ii3artikW4blfeIIldMd0=; b=VAMBJO11xNobhy/hXXXbHnoPLXjkEX1PzEWr/DWiLz3yn5q9rLIJygIwxWmuCyN17S P1zRCzc8KlhMOHwkMlPDFoOiaUW2hYqrtGElDL9ZFtlknBz8ZTiQu60vQ9AwYwCLpynu Yc9WusKTrPGDM21SbmZBj3HKjYYDXS1aH/3y09sDhoSKjGyUBKbUr8zNj5/XCfd8gElx AyQmHzFad65t6w23IoIOwgp/Uhv+xIsZsl7SYyrAY88KFFJ02uOHy7W8p+YiswJmnEFy qtmsRICz1Kk4BrhmPRu3OxjoAJrVLpAdjQ7vkKpqkVytFQC389faM1Bc2XLE+ilm/8DE CbQQ== X-Gm-Message-State: AJcUukexYnSahgMGzbClcM5sG7ICEkhR1fs74VJ5L/Oddv9szL+WrnoF 3GLs1me8dXRtHVq2M1KCj506rg== X-Google-Smtp-Source: ALg8bN4S08UUWqbIrMre1jsuHPOP5jNs8ak9lpP/eDaOnHnI10UDLs/RR0y5MsIL8pV6zwa/X63ZzA== X-Received: by 2002:a24:89:: with SMTP id 131mr5479335ita.105.1547652324969; Wed, 16 Jan 2019 07:25:24 -0800 (PST) Received: from [192.168.1.56] ([216.160.245.98]) by smtp.gmail.com with ESMTPSA id r16sm2561959ioa.16.2019.01.16.07.25.22 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 16 Jan 2019 07:25:23 -0800 (PST) Subject: Re: [PATCH 05/16] Add io_uring IO interface To: Arnd Bergmann Cc: Linux FS-devel Mailing List , linux-aio , linux-block , linux-arch , Christoph Hellwig , Jeff Moyer , Avi Kivity References: <20190115025531.13985-1-axboe@kernel.dk> <20190115025531.13985-6-axboe@kernel.dk> <15b06ccb-4501-f104-9a3a-f028218a0d70@kernel.dk> From: Jens Axboe Message-ID: <6713aff7-115b-bb94-fb8c-b4fac86247f1@kernel.dk> Date: Wed, 16 Jan 2019 08:25:21 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 1/16/19 8:16 AM, Arnd Bergmann wrote: > On Wed, Jan 16, 2019 at 4:12 PM Jens Axboe wrote: >> On 1/16/19 3:41 AM, Arnd Bergmann wrote: >>> On Tue, Jan 15, 2019 at 3:55 AM Jens Axboe wrote: >>>> diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl >>>> index 3cf7b533b3d1..194e79c0032e 100644 >>>> --- a/arch/x86/entry/syscalls/syscall_32.tbl >>>> +++ b/arch/x86/entry/syscalls/syscall_32.tbl >>>> +SYSCALL_DEFINE2(io_uring_setup, u32, entries, >>>> + struct io_uring_params __user *, params) >>>> +{ >>>> + return io_uring_setup(entries, params, false); >>>> +} >>>> + >>>> +#ifdef CONFIG_COMPAT >>>> +COMPAT_SYSCALL_DEFINE2(io_uring_setup, u32, entries, >>>> + struct io_uring_params __user *, params) >>>> +{ >>>> + return io_uring_setup(entries, params, true); >>>> +} >>>> +#endif >>> >>> The compat syscall has the same calling conventions as the >>> native one here, so I think you can just use that directly. >> >> Not sure I understand what you mean here. I need to know if it's the >> compat one, hence 'true' vs 'false', so I know what the size of the user >> pointers/structs are. > > My mistake, I missed the true/false difference between the two > functions. > >>>> +/* >>>> + * IO submission data structure (Submission Queue Entry) >>>> + */ >>>> +struct io_uring_sqe { >>>> + __u8 opcode; /* type of operation for this sqe */ >>>> + __u8 flags; /* as of now unused */ >>>> + __u16 ioprio; /* ioprio for the request */ >>>> + __s32 fd; /* file descriptor to do IO on */ >>>> + __u64 off; /* offset into file */ >>>> + union { >>>> + void *addr; /* buffer or iovecs */ >>>> + __u64 __pad; >>>> + }; >>> >>> It seems a bit unfortunate to keep the pointer field only >>> almost compatible between 32-bit and 64-bit big-endian >>> architectures, as that requires an in_compat_syscall() >>> check whenever we access the pointer from the kernel. >>> >>> Could you use a __u64 field to store the pointer itself >>> instead? >> >> I feel like I'm missing something here, we'll still need the compat code >> on the kernel side for 32-bit app on 64-bit kernel, so what would we >> solve by making this an __u64? > > It means you don't have to define a compat_io_uring_sqe > structure with a compat_uptr_t member in it. Yeah, I finally got it, I'm making the change. Thanks! -- Jens Axboe