From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757716Ab0IGPhh (ORCPT ); Tue, 7 Sep 2010 11:37:37 -0400 Received: from earthlight.etchedpixels.co.uk ([81.2.110.250]:59875 "EHLO www.etchedpixels.co.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757593Ab0IGPhc (ORCPT ); Tue, 7 Sep 2010 11:37:32 -0400 Date: Tue, 7 Sep 2010 16:55:38 +0100 From: Alan Cox To: Ingo Molnar Cc: Avi Kivity , Pekka Enberg , Tom Zanussi , =?ISO-8859-14?B?RnLpZOlyaWM=?= Weisbecker , Steven Rostedt , Arnaldo Carvalho de Melo , Peter Zijlstra , linux-perf-users@vger.kernel.org, linux-kernel Subject: Re: disabling group leader perf_event Message-ID: <20100907165538.295db171@lxorguk.ukuu.org.uk> In-Reply-To: <20100907034417.GA14046@elte.hu> References: <1283772256.1930.303.camel@laptop> <4C84D1CE.3070205@redhat.com> <1283774045.1930.341.camel@laptop> <4C84D77B.6040600@redhat.com> <20100906124330.GA22314@elte.hu> <4C84E265.1020402@redhat.com> <20100906125905.GA25414@elte.hu> <4C850147.8010908@redhat.com> <20100906154737.GA4332@elte.hu> <4C852B2A.2030103@redhat.com> <20100907034417.GA14046@elte.hu> X-Mailer: Claws Mail 3.7.6 (GTK+ 2.18.9; x86_64-redhat-linux-gnu) Face: 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 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Safety of #1 (x86 bytecode passed in by untrusted user-space, verified > and saved by the kernel and executed natively as an x86 function if it > passes the security checks) is trivial but obviously needs quite a bit > of work. Hardly trivial - and it will always be buggy. As well as the fact your interpreter is going to have bugs its also no longer portable. If you have a sane input code and verify that then compile it you get portability and verifiability. > > Can you point me to any research? > > Nope, havent seen this 'safe native x86 bytecode' idea > mentioned/researched anywhere yet. Its been done as a linux arch experiment using a trusted assembler. > I think some Java-like bytecode is roughly the same amount of conceptual > work as an x86 bytecode verifier, with the big disadvantage that even > with a JIT it's much slower [and a JIT is far from simple] - not to > mention the non-technical complications of Java. The Java JIT is horrible. A better intermediate with compiler available looks more promising. How about the qemu or valgrind intermediates ? > > > I have a truly marvellous patch that fixes the bug which this > > signature is too narrow to contain. > > Make sure you write down a short but buggy version of the patch on the > margin of a book. Pass on the book to your heirs and enjoy the centuries > long confusion from the heavens. I'm sure the perl version will fit ;) Alan