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_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, 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 C96AEC43610 for ; Thu, 29 Nov 2018 18:17:14 +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 A0F51213A2 for ; Thu, 29 Nov 2018 18:17:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="oiUJWfoB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A0F51213A2 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=t1CfEfLMsiZ4Tt+W58fVockJYA8PutjSAtSCEPiE5fc=; b=oiUJWfoBpg/ekc 3lg7Mf5eyW1s2rVOF5tfE1aSTOwf4zte3CzbBlWg+WXz9Z60eyXgU0jiiNCVbzmoApxPdl3mkh4cy +uHAvk+orWfxbYVlURn7pn/OudNQu3tt10lJglOaypWC/NI79tDfVFYzDTMDngY5oF4V40x2DUfqy Sg0BR1SeWL4XU3dwBsUo6L6sR1UJeGhmM+37kxbtM9e2RmHqnA0DFT4kRrNwq9tB4BEKil60f0DRV HpGlNCG9jxSZoTvdLRSbGgF78KNE3vTBbQdtsbpyIHL/4c/KcdUyLQs8P5HIBWQu2Twh8QwcznLkc amP+vQN+AwOnTLVFPrLg==; 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 1gSQsC-0004yl-NQ; Thu, 29 Nov 2018 18:17:12 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gSQsA-0004ri-CJ for linux-arm-kernel@lists.infradead.org; Thu, 29 Nov 2018 18:17:11 +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 A3E0980D; Thu, 29 Nov 2018 10:16:57 -0800 (PST) Received: from arrakis.emea.arm.com (arrakis.cambridge.arm.com [10.1.196.113]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 88E2A3F575; Thu, 29 Nov 2018 10:16:53 -0800 (PST) Date: Thu, 29 Nov 2018 18:16:51 +0000 From: Catalin Marinas To: Andrey Konovalov Subject: Re: [PATCH v8 0/8] arm64: untag user pointers passed to the kernel Message-ID: <20181129181650.GG22027@arrakis.emea.arm.com> References: 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-20181129_101710_453260_6E69A26E X-CRM114-Status: GOOD ( 21.28 ) 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 , Kate Stewart , "open list:DOCUMENTATION" , Will Deacon , Linux Memory Management List , "open list:KERNEL SELFTEST FRAMEWORK" , Chintan Pandya , Shuah Khan , Ingo Molnar , linux-arch , Jacob Bramley , Dmitry Vyukov , Evgeniy Stepanov , Kees Cook , Ruben Ayrapetyan , Ramana Radhakrishnan , Linux ARM , Kostya Serebryany , Greg Kroah-Hartman , LKML , "Kirill A . Shutemov" , Lee Smith , Andrew Morton , Robin Murphy , 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 Hi Andrey, On Thu, Nov 08, 2018 at 03:48:10PM +0100, Andrey Konovalov wrote: > On Thu, Nov 8, 2018 at 3:36 PM, Andrey Konovalov wrote: > > Changes in v8: > > - Rebased onto 65102238 (4.20-rc1). > > - Added a note to the cover letter on why syscall wrappers/shims that untag > > user pointers won't work. > > - Added a note to the cover letter that this patchset has been merged into > > the Pixel 2 kernel tree. > > - Documentation fixes, in particular added a list of syscalls that don't > > support tagged user pointers. > > I've changed the documentation to be more specific, please take a look. > > I haven't done anything about adding a way for the user to find out > that the kernel supports this ABI extension. I don't know what would > the the preferred way to do this, and we haven't received any comments > on that from anybody else. Probing "on some innocuous syscall > currently returning -EFAULT on tagged pointer arguments" works though, > as you mentioned. We've had some internal discussions and also talked to some people at Plumbers. I think the best option is to introduce an AT_FLAGS bit to describe the ABI relaxation on tagged pointers. Vincenzo is going to propose a patch on top of this series. > As mentioned in the cover letter, this patchset has been merged into > the Pixel 2 kernel tree. I just hope it's not enabled on production kernels, it would introduce a user ABI that may differ from what ends up upstream. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel