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=-2.5 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, T_DKIMWL_WL_HIGH,URIBL_BLOCKED,USER_AGENT_MUTT 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 B6541C28CC4 for ; Fri, 31 May 2019 16:20:16 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 8D03626BEB for ; Fri, 31 May 2019 16:20:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="mEuvSncc" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8D03626BEB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=AkBtVyDQ+ZDQKh8wKzljkbwMRS9OJq3SDHwfZJIxc/Y=; b=mEuvSnccVlcxpR NoqYa8IR3Wgfo2ImTwAQa57oiOaDttH0Kt5kEKT8uutmkOt6fNnMstzZCqSyR5fg+ilPpuGA/pcXt gtUN+ndB8aWbbG+LaMlhWuRVaPUjqdk57URj6I0ca+l27TZUpm+8kVocFk7/o1w5oW8bMrDUEES/H nDXqsBFar4oih36h6yqpY+buXucxLQDXR5ipiaqWImNkAJWuYcTqKFl1rlzt+AGN5UrAiPatLXXwY 3olUOlQ0x1Ga4zgLkG5dLiO4jua0LulVYcmKR4W+g71AN1vu68jj4wsgKWKitYtmbby44fefl2uxg aW0EG3RWIbgG9f1SqoWg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hWkGH-0007Ra-HD; Fri, 31 May 2019 16:20:09 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hWkGD-0006gi-VR for linux-arm-kernel@lists.infradead.org; Fri, 31 May 2019 16:20:07 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9E486341; Fri, 31 May 2019 09:20:03 -0700 (PDT) Received: from arrakis.emea.arm.com (arrakis.cambridge.arm.com [10.1.196.78]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B67CE3F59C; Fri, 31 May 2019 09:19:57 -0700 (PDT) Date: Fri, 31 May 2019 17:19:55 +0100 From: Catalin Marinas To: Andrey Konovalov Subject: Re: [PATCH v15 00/17] arm64: untag user pointers passed to the kernel Message-ID: <20190531161954.GA3568@arrakis.emea.arm.com> References: <20190521182932.sm4vxweuwo5ermyd@mbp> <201905211633.6C0BF0C2@keescook> <6049844a-65f5-f513-5b58-7141588fef2b@oracle.com> <20190523201105.oifkksus4rzcwqt4@mbp> <20190524101139.36yre4af22bkvatx@mbp> <20190530171540.GD35418@arrakis.emea.arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190531_092006_028854_FD1CB9F4 X-CRM114-Status: GOOD ( 21.88 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , kvm@vger.kernel.org, Szabolcs Nagy , Will Deacon , dri-devel@lists.freedesktop.org, Linux Memory Management List , Khalid Aziz , "open list:KERNEL SELFTEST FRAMEWORK" , Vincenzo Frascino , Jacob Bramley , Leon Romanovsky , linux-rdma@vger.kernel.org, amd-gfx@lists.freedesktop.org, Dmitry Vyukov , Dave Martin , Evgenii Stepanov , linux-media@vger.kernel.org, Kevin Brodsky , Kees Cook , Ruben Ayrapetyan , Ramana Radhakrishnan , Alex Williamson , Yishai Hadas , Mauro Carvalho Chehab , Linux ARM , Kostya Serebryany , Greg Kroah-Hartman , Felix Kuehling , LKML , Jens Wiklander , Lee Smith , Alexander Deucher , Andrew Morton , Elliott Hughes , Robin Murphy , Christian Koenig , Luc Van Oostenryck Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, May 31, 2019 at 04:29:10PM +0200, Andrey Konovalov wrote: > On Thu, May 30, 2019 at 7:15 PM Catalin Marinas wrote: > > On Tue, May 28, 2019 at 04:14:45PM +0200, Andrey Konovalov wrote: > > > Thanks for a lot of valuable input! I've read through all the replies > > > and got somewhat lost. What are the changes I need to do to this > > > series? > > > > > > 1. Should I move untagging for memory syscalls back to the generic > > > code so other arches would make use of it as well, or should I keep > > > the arm64 specific memory syscalls wrappers and address the comments > > > on that patch? > > > > Keep them generic again but make sure we get agreement with Khalid on > > the actual ABI implications for sparc. > > OK, will do. I find it hard to understand what the ABI implications > are. I'll post the next version without untagging in brk, mmap, > munmap, mremap (for new_address), mmap_pgoff, remap_file_pages, shmat > and shmdt. It's more about not relaxing the ABI to accept non-zero top-byte unless we have a use-case for it. For mmap() etc., I don't think that's needed but if you think otherwise, please raise it. > > > 2. Should I make untagging opt-in and controlled by a command line argument? > > > > Opt-in, yes, but per task rather than kernel command line option. > > prctl() is a possibility of opting in. > > OK. Should I store a flag somewhere in task_struct? Should it be > inheritable on clone? A TIF flag would do but I'd say leave it out for now (default opted in) until we figure out the best way to do this (can be a patch on top of this series). Thanks. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel