From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752448Ab1JJGLO (ORCPT ); Mon, 10 Oct 2011 02:11:14 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:42516 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751725Ab1JJGLN (ORCPT ); Mon, 10 Oct 2011 02:11:13 -0400 Date: Mon, 10 Oct 2011 08:09:27 +0200 From: Ingo Molnar To: Masami Hiramatsu Cc: Peter Zijlstra , Stephane Eranian , Andi Kleen , linux-kernel@vger.kernel.org, acme@redhat.com, ming.m.lin@intel.com, robert.richter@amd.com, ravitillo@lbl.gov Subject: Re: [PATCH 07/12] perf_events: add LBR software filter support for Intel X86 Message-ID: <20111010060927.GG32173@elte.hu> References: <1317912555-9559-1-git-send-email-eranian@google.com> <1317912555-9559-8-git-send-email-eranian@google.com> <20111006153229.GJ14482@one.firstfloor.org> <1317984122.31132.6.camel@twins> <1317986519.31132.13.camel@twins> <4E8EE885.9040703@hitachi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4E8EE885.9040703@hitachi.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.3.1 -2.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Masami Hiramatsu wrote: > (2011/10/07 20:21), Peter Zijlstra wrote: > > On Fri, 2011-10-07 at 13:18 +0200, Peter Zijlstra wrote: > >>> Yeah, depending on the depth of the LBR. But then what happens, you > >>> decode an instruction that is not what was executed. > >> > >> Right, and Andi's concern is that this might cause our instruction > >> decoder to blow up, or worse. > > > > That is, we have a fair confidence that its capable of correctly > > decoding correct streams, but I understood from Masami that they haven't > > actually tried feeding it crap. > > OK, I'll do hardening it. Yes, that's a good idea. Could you perhaps add it to the existing build time sanity test we do for the instruction decoder, to feed it a sequence of /dev/urandom input or such? Thanks, Ingo