From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756117AbZB1WRY (ORCPT ); Sat, 28 Feb 2009 17:17:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754671AbZB1WRQ (ORCPT ); Sat, 28 Feb 2009 17:17:16 -0500 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:37690 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754526AbZB1WRP (ORCPT ); Sat, 28 Feb 2009 17:17:15 -0500 Date: Sat, 28 Feb 2009 23:19:44 +0100 From: Pavel Machek To: Andi Kleen Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/6] ftrace, x86: make kernel text writable only for conversions Message-ID: <20090228221944.GG21230@elf.ucw.cz> References: <20090220011316.379904625@goodmis.org> <20090220011521.003556651@goodmis.org> <87y6vyuzsn.fsf@basil.nowhere.org> <20090227210856.GB1476@ucw.cz> <20090228165624.GC26292@one.firstfloor.org> <20090228220829.GE21230@elf.ucw.cz> <87wsba1a9f.fsf@basil.nowhere.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87wsba1a9f.fsf@basil.nowhere.org> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat 2009-02-28 23:12:28, Andi Kleen wrote: > Pavel Machek writes: > > [trimmed cc list] > > >> If you mean other attributes like large page vs small page: it's normally legal, > >> with a few exceptions. > > > > ...but is it okay on other architectures, like sparc, with funky cache > > setups? > > I don't know for sure (how about you look it up in a sparc manual?), but > I would assume it's also not safe there. I know it's not allowed in IA64 > at least, with even some stricter rules than on x86. So using aliases for kernel text rewriting is bad idea because it would break ia64? That was what the thread was about. (Sorry, no ia64 or sparc manuals nearby). Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html