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=-0.8 required=3.0 tests=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 C2DA6C47254 for ; Fri, 1 May 2020 07:46:58 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 965BF21924 for ; Fri, 1 May 2020 07:46:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 965BF21924 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=ACULAB.COM Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvdimm-bounces@lists.01.org Received: from ml01.vlan13.01.org (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 5581C10053E29; Fri, 1 May 2020 00:45:42 -0700 (PDT) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=207.82.80.151; helo=eu-smtp-delivery-151.mimecast.com; envelope-from=david.laight@aculab.com; receiver= Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [207.82.80.151]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id DDBE310053E02 for ; Fri, 1 May 2020 00:45:38 -0700 (PDT) Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-236-crWB7YfiO5yLJYsQLeM4Tg-1; Fri, 01 May 2020 08:46:50 +0100 X-MC-Unique: crWB7YfiO5yLJYsQLeM4Tg-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Fri, 1 May 2020 08:46:49 +0100 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Fri, 1 May 2020 08:46:49 +0100 From: David Laight To: 'Andy Lutomirski' , Linus Torvalds Subject: RE: [PATCH v2 0/2] Replace and improve "mcsafe" with copy_safe() Thread-Topic: [PATCH v2 0/2] Replace and improve "mcsafe" with copy_safe() Thread-Index: AQHWHx8fSK33XHL44ESHjM2jwgOtw6iS1wyw Date: Fri, 1 May 2020 07:46:48 +0000 Message-ID: <6c0ca300a3b54b86abac79d6549a0a40@AcuMS.aculab.com> References: <158823509800.2094061.9683997333958344535.stgit@dwillia2-desk3.amr.corp.intel.com>

In-Reply-To: Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Message-ID-Hash: EMKNU2CUZ44HA5ZQ7ZRNWGTEOYYS67O7 X-Message-ID-Hash: EMKNU2CUZ44HA5ZQ7ZRNWGTEOYYS67O7 X-MailFrom: david.laight@aculab.com X-Mailman-Rule-Hits: nonmember-moderation X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation CC: Thomas Gleixner , Ingo Molnar , Tony Luck , Peter Zijlstra , Borislav Petkov , stable , the arch/x86 maintainers , "H. Peter Anvin" , Paul Mackerras , Benjamin Herrenschmidt , "Erwin Tsaur , Michael Ellerman , Arnaldo Carvalho de Melo" , linux-nvdimm , Linux Kernel Mailing List X-Mailman-Version: 3.1.1 Precedence: list List-Id: "Linux-nvdimm developer list." Archived-At: List-Archive: List-Help: List-Post: List-Subscribe: List-Unsubscribe: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit From: Andy Lutomirski > Sent: 30 April 2020 19:42 ... > I suppose there could be a consistent naming like this: > > copy_from_user() > copy_to_user() > > copy_from_unchecked_kernel_address() [what probe_kernel_read() is] > copy_to_unchecked_kernel_address() [what probe_kernel_write() is] > > copy_from_fallible() [from a kernel address that can fail to a kernel > address that can't fail] > copy_to_fallible() [the opposite, but hopefully identical to memcpy() on x86] > > copy_from_fallible_to_user() > copy_from_user_to_fallible() You missed out: copy_to/from_io() copy_to_io_from_user() copy_from_io_to_user() All of which want aligned addresses on the 'io' side. It might even be worth saying that the copy_to/from_io() can fail due to bad IO accesses (rather than bad addresses). This is not entirely unexpected since all PCIe accesses can fail unexpectedly (usually without a trap and returning -1). But a system could arrange to generate a synchronous fault. If you are copying directly from io to user you need to differentiate between a user page fault and an io access error. The latter shouldn't generate SIGSEGV. Possibly return -EFAULT on user page fault and 'transfer length remaining' on io access error. Although filling the rest of the buffer with 0xff might be appropriate. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales) _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org