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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 F3708C43219 for ; Fri, 3 May 2019 13:55:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C57142087F for ; Fri, 3 May 2019 13:55:18 +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="rSOqH7Y7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727843AbfECNzO (ORCPT ); Fri, 3 May 2019 09:55:14 -0400 Received: from merlin.infradead.org ([205.233.59.134]:37666 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726047AbfECNzO (ORCPT ); Fri, 3 May 2019 09:55:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=ALgcqCtqCqOGvegvBJbnoppT5gDBB9wFVtxlPQfWxJ4=; b=rSOqH7Y7dB0q+WGGArvuwubx2 xfwvuCL173N0TCzBY+atLybyrLySXjcFgnAuDB8FDkwz4P83zwvfLEkfttt19qPsUaWk5BhfDDiZi fwMATyBMZIZlT7lGLCH4dQUagQ1e0fofItj807gvtD9qhAIg7T5COxrdTkex45Rl/8wR4o+bxZHBr L5vye6VwsVHFezQ4IAAkyAjxOp3Wev/avoiLulN2JVhOpNyubPm7SwSRpzdiC6BbT9PwzkVrfW+2I cbxla5CLXbdTIL9z3iQtQuWGZkybFsRssW+yWrR41P9r6XKD5NHS/ztQeHc1Qo6fnYI6u+kUPj5Xr DGW79aGQg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hMYdw-0007F7-1b; Fri, 03 May 2019 13:54:28 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 39C93214242EB; Fri, 3 May 2019 15:54:26 +0200 (CEST) Date: Fri, 3 May 2019 15:54:26 +0200 From: Peter Zijlstra To: Joel Fernandes Cc: Qais Yousef , linux-kernel@vger.kernel.org, Michal Gregorczyk , Adrian Ratiu , Mohammad Husain , Srinivas Ramana , duyuchao , Manjo Raja Rao , Karim Yaghmour , Tamir Carmeli , Yonghong Song , Alexei Starovoitov , Brendan Gregg , Masami Hiramatsu , Steven Rostedt , Kees Cook , kernel-team@android.com, Daniel Borkmann , Ingo Molnar , netdev@vger.kernel.org Subject: Re: [PATCH RFC] bpf: Add support for reading user pointers Message-ID: <20190503135426.GA2606@hirez.programming.kicks-ass.net> References: <20190502204958.7868-1-joel@joelfernandes.org> <20190503121234.6don256zuvfjtdg6@e107158-lin.cambridge.arm.com> <20190503134935.GA253329@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190503134935.GA253329@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, May 03, 2019 at 09:49:35AM -0400, Joel Fernandes wrote: > In > particular, we learnt with extensive discussions that user/kernel pointers > are not necessarily distinguishable purely based on their address. This is correct; a number of architectures have a completely separate user and kernel address space. Much like how the old i386 4G:4G patches worked.