Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933053Ab1EMQYT (ORCPT ); Fri, 13 May 2011 12:24:19 -0400 Received: from mga09.intel.com ([134.134.136.24]:28670 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932618Ab1EMQYS (ORCPT ); Fri, 13 May 2011 12:24:18 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.64,365,1301900400"; d="scan'208";a="746885609" From: Andi Kleen To: Ingo Molnar Cc: Dave Jones , Stephane Eranian , Linus Torvalds , Arnaldo Carvalho de Melo , LKML , "H. Peter Anvin" , Thomas Gleixner , Arjan van de Ven Subject: Re: [BUG] perf: bogus correlation of kernel symbols References: <20110512213542.GB17596@elte.hu> <20110512215023.GA20939@elte.hu> <20110512220715.GA7451@redhat.com> <20110513085752.GF13647@elte.hu> Date: Fri, 13 May 2011 09:23:52 -0700 In-Reply-To: <20110513085752.GF13647@elte.hu> (Ingo Molnar's message of "Fri, 13 May 2011 10:57:52 +0200") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1338 Lines: 35 Ingo Molnar writes: I agree that the current %kP default is really a catastrophe, clearly on the trajectory of "the system is only secure when nothing works anymore" > The x86 kernel is relocatable, so slightly randomizing the position of the > kernel would be feasible with no overhead on the vast majority of exising > distro installs, with just an updated kernel. Problem is that we don't have a source of secure randomness early on when the relocation would need to happen. You could either pass it as an option, but that option would be right now too exposed, or just use kexec and boot twice. But all of this has drawbacks. > When exposing randomized RIPs to user-space we could recalculate all RIPs back > to the 0xffffffff80000000 base, so oopses would have the usual non-randomized > form: This would be very confusing because the register and stack contents would have the non relocated addresses. I bet it would cause a lot of similar problems as the current %kP madness, just more subtle ones. -Andi -- ak@linux.intel.com -- Speaking for myself only -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/