From owner-freebsd-current@FreeBSD.ORG Thu Jun 16 00:44:18 2011 Return-Path: Delivered-To: current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 417811065674 for ; Thu, 16 Jun 2011 00:44:18 +0000 (UTC) (envelope-from julian@freebsd.org) Received: from vps1.elischer.org (vps1.elischer.org [204.109.63.16]) by mx1.freebsd.org (Postfix) with ESMTP id 136138FC1E for ; Thu, 16 Jun 2011 00:44:17 +0000 (UTC) Received: from julian-mac.elischer.org (home-nat.elischer.org [67.100.89.137]) (authenticated bits=0) by vps1.elischer.org (8.14.4/8.14.4) with ESMTP id p5G0iB5j072193 (version=TLSv1/SSLv3 cipher=DHE-RSA-CAMELLIA256-SHA bits=256 verify=NO); Wed, 15 Jun 2011 17:44:14 -0700 (PDT) (envelope-from julian@freebsd.org) Message-ID: <4DF951E3.7010209@freebsd.org> Date: Wed, 15 Jun 2011 17:44:19 -0700 From: Julian Elischer User-Agent: Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10.4; en-US; rv:1.9.2.17) Gecko/20110414 Thunderbird/3.1.10 MIME-Version: 1.0 To: Scott Long References: <20110614161105.GA17306@onelab2.iet.unipi.it> <4A46AC77-BEE5-4401-8896-4E4F1A5304B0@samsco.org> In-Reply-To: <4A46AC77-BEE5-4401-8896-4E4F1A5304B0@samsco.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Luigi Rizzo , "K. Macy" , current@freebsd.org Subject: Re: fast/syscall-free gettimeofday ? X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 16 Jun 2011 00:44:18 -0000 > If this was to be extended with cached global syscall information like gettimeofday, would we want that to be in a separate page that is marked non-executable? Is there any way to trick the kernel into leaking arbitrary (and thus executable) code? Also, would it matter for jails? Per-process info like getpid would obviously have to be a separate per-process page. > > Scott > In the talk about this sort of topic I have seen mention at various times of a page per system, a page per jail, a page per process and a page per thread. I'm not saying we want this all just that I've seen it mentionned.. The per-thread one is the most intersting to do challenge wise.