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=-5.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,TVD_SUBJ_WIPE_DEBT,USER_AGENT_GIT 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 165D9C433E2 for ; Thu, 3 Sep 2020 14:48:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E0F5320DD4 for ; Thu, 3 Sep 2020 14:48:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="H1ysAq3n" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729207AbgICOr7 (ORCPT ); Thu, 3 Sep 2020 10:47:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35162 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729156AbgICOX1 (ORCPT ); Thu, 3 Sep 2020 10:23:27 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6D00CC06124F; Thu, 3 Sep 2020 07:22:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:In-Reply-To:References; bh=Nmt3gQrXHRpJsq5nosMrsljZettvm0yOX7zhocjtN3o=; b=H1ysAq3n3J6+FAOCcSXFaaRG8D fuHtZL4njNSPBAI3AAdu+2NhFbCA0M/aFer+STq20lof8lzzLkcHwR+4mUTX+D0OnGGRKirmYoTjG EdnkecbKc4QL1WDsCKuG9gjFRHY4W+kA3NaiFvzHmE7krKfzPxtpP//6nMpTok5F3qQKEfpKv2Wk+ B/I87rPNxRr3SGs9cjQH2lP62Am3AmAkrgJHUCDx6nxKWYJ9IGmyL8OPQ/S5+kXwOaGOIk6OHjy+D vtZSYF0uJln0Jn1YMjj1NEYT4k/z9t438BC2mqYo5NUFChlAdhDU8L6mp+Ue0DSSntfuCiP05e1qW Ddh3SSAg==; Received: from [2001:4bb8:184:af1:c70:4a89:bc61:2] (helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kDq8R-0004a3-Rf; Thu, 03 Sep 2020 14:22:44 +0000 From: Christoph Hellwig To: Linus Torvalds , Al Viro , Michael Ellerman , x86@kernel.org Cc: Alexey Dobriyan , Luis Chamberlain , Kees Cook , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: remove the last set_fs() in common code, and remove it for x86 and powerpc v3 Date: Thu, 3 Sep 2020 16:22:28 +0200 Message-Id: <20200903142242.925828-1-hch@lst.de> X-Mailer: git-send-email 2.28.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-arch-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org Hi all, this series removes the last set_fs() used to force a kernel address space for the uaccess code in the kernel read/write/splice code, and then stops implementing the address space overrides entirely for x86 and powerpc. [Note to Linus: I'd like to get this into linux-next rather earlier than later. Do you think it is ok to add this tree to linux-next?] The file system part has been posted a few times, and the read/write side has been pretty much unchanced. For splice this series drops the conversion of the seq_file and sysctl code to the iter ops, and thus loses the splice support for them. The reasons for that is that it caused a lot of churn for not much use - splice for these small files really isn't much of a win, even if existing userspace uses it. All callers I found do the proper fallback, but if this turns out to be an issue the conversion can be resurrected. Besides x86 and powerpc I plan to eventually convert all other architectures, although this will be a slow process, starting with the easier ones once the infrastructure is merged. The process to convert architectures is roughtly: (1) ensure there is no set_fs(KERNEL_DS) left in arch specific code (2) implement __get_kernel_nofault and __put_kernel_nofault (3) remove the arch specific address limitation functionality Changes since v2: - add back the patch to support splice through read_iter/write iter on /proc/sys/* - entirely remove the tests that depend on set_fs. Note that for lkdtm the maintainer (Kees) disagrees with this request from Linus - fix a wrong check in the powerpc access_ok, and drop a few spurious cleanups there Changes since v1: - drop the patch to remove the non-iter ops for /dev/zero and /dev/null as they caused a performance regression - don't enable user access in __get_kernel on powerpc - xfail the set_fs() based lkdtm tests Diffstat: