Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752495Ab1EMGYT (ORCPT ); Fri, 13 May 2011 02:24:19 -0400 Received: from mail-gy0-f174.google.com ([209.85.160.174]:35168 "EHLO mail-gy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751148Ab1EMGYS convert rfc822-to-8bit (ORCPT ); Fri, 13 May 2011 02:24:18 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=YQKBGCYCnEpOSQZCpgLYj+UY1HxDopc4Juvmew25FcxbZ6dBxBpN59srt+kEN0Nvmz Wun71PMWLxo4rrL3DK5Ipp7DVLIfLzAHmfDf4G4Dr/Nk/Iz+uadiInfJlNvneTUlWtKw E4ie3SfQ/NEP3BsKrlAzHJ0rRdUAMbHRPKbkk= MIME-Version: 1.0 In-Reply-To: <20110513061252.GV28888@outflux.net> References: <20110512.140630.1779004012724490077.davem@davemloft.net> <20110512183741.GA22269@redhat.com> <20110512.150132.1679483014638599288.davem@davemloft.net> <20110513061252.GV28888@outflux.net> Date: Fri, 13 May 2011 09:24:17 +0300 X-Google-Sender-Auth: 4MWrxHoR27fHZZ6dA0ziJZHkm_Y Message-ID: Subject: Re: [BUG] perf: bogus correlation of kernel symbols From: Pekka Enberg To: Kees Cook Cc: David Miller , davej@redhat.com, eranian@google.com, acme@redhat.com, linux-kernel@vger.kernel.org, Linus Torvalds , Ingo Molnar Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1935 Lines: 46 Hi Kees, On Fri, May 13, 2011 at 9:12 AM, Kees Cook wrote: > Hi Pekka, > > On Thu, May 12, 2011 at 10:58:53PM +0300, Pekka Enberg wrote: >> On Thu, May 12, 2011 at 10:01 PM, David Miller wrote: >> > From: Dave Jones >> > Date: Thu, 12 May 2011 14:37:41 -0400 >> > >> >> On Thu, May 12, 2011 at 02:06:30PM -0400, David Miller wrote: >> >> ?> I hate this too, and I think it's absolutely rediculous. >> >> ?> >> >> ?> Also, like you, I lost an entire afternoon trying to figure out why >> >> ?> this started happening. >> >> ?> >> >> ?> I wish we could revert this change. >> >> >> >> At least it can be permanently disabled.. >> >> >> >> echo kernel.kptr_restrict = 0 >> /etc/sysctl.conf >> > >> > Regardless, what to do about all of the "perf is broken" reports? >> >> Lets revert the commit 9f36e2c448007b54851e7e4fa48da97d1477a175 >> ("printk: use %pK for /proc/kallsyms and /proc/modules"), please! I >> too have been wondering what's going on with perf reporting insane >> symbols and this should definitely not be enabled by default. > > No, reverting that is not the answer. If perf has a problem with the > kptr_restrict feature, it should just disable it in /proc/sys when it > runs and restore it when finished. Since our defaults should be secure > for the average user (who does not use perf), it's fine the way it > is. Anyone using perf can adjust this for their use-case (that is why > there is a /proc/sys tunable). No, it's the other way around. See commit 411f05f123cbd7f8aa1edcae86970755a6e2a9d9 ("vsprintf: Turn kptr_restrict off by default") in Linus' tree for details. Pekka -- 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/