From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964968AbWAXHHW (ORCPT ); Tue, 24 Jan 2006 02:07:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932426AbWAXHHW (ORCPT ); Tue, 24 Jan 2006 02:07:22 -0500 Received: from pentafluge.infradead.org ([213.146.154.40]:39583 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S932239AbWAXHHV (ORCPT ); Tue, 24 Jan 2006 02:07:21 -0500 Subject: Re: [PATCH/RFC] Shared page tables From: Arjan van de Ven To: Andi Kleen Cc: Ray Bryant , Dave McCracken , Robin Holt , Hugh Dickins , Linux Kernel , Linux Memory Management In-Reply-To: <200601240210.04337.ak@suse.de> References: <200601240139.46751.ak@suse.de> <200601231853.54948.raybry@mpdtxmail.amd.com> <200601240210.04337.ak@suse.de> Content-Type: text/plain Date: Tue, 24 Jan 2006 08:06:37 +0100 Message-Id: <1138086398.2977.19.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > The randomization is not for cache coloring, but for security purposes > (except for the old very small stack randomization that was used > to avoid conflicts on HyperThreaded CPUs). I would be surprised if the > mmap made much difference because it's page aligned and at least > on x86 the L2 and larger caches are usually PI. randomization to a large degree is more important between machines than within the same machine (except for setuid stuff but lets call that a special category for now). Imo prelink is one of the better bets to get "all code for a binary/lib on the same 2 mb page", all distros ship prelink nowadays anyway (it's too much of a win that nobody can afford to not ship it ;) and within prelink the balance between randomization for security and 2Mb sharing can be struck best. In fact it needs know about the 2Mb thing anyway to place it there properly and for all binaries... the kernel just can't do that.