Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933183AbaFTAhc (ORCPT ); Thu, 19 Jun 2014 20:37:32 -0400 Received: from ozlabs.org ([103.22.144.67]:51445 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754038AbaFTAha (ORCPT ); Thu, 19 Jun 2014 20:37:30 -0400 Message-ID: <1403224646.18509.1.camel@concordia> Subject: Re: Re: Re: [RFT PATCH -next v3] [BUGFIX] kprobes: Fix "Failed to find blacklist" error on ia64 and ppc64 From: Michael Ellerman To: Masami Hiramatsu Cc: "Suzuki K. Poulose" , Benjamin Herrenschmidt , Tony Luck , Paul Mackerras , Jeremy Fitzhardinge , linux-ia64@vger.kernel.org, sparse@chrisli.org, "H. Peter Anvin" , Thomas Gleixner , linux-tip-commits@vger.kernel.org, anil.s.keshavamurthy@intel.com, Ingo Molnar , Fenghua Yu , Arnd Bergmann , Rusty Russell , Chris Wright , yrl.pp-manager.tt@hitachi.com, akataria@vmware.com, Tony Luck , Kevin Hao , Linus Torvalds , rdunlap@infradead.org, Linux Kernel Mailing List , dl9pf@gmx.de, Andrew Morton , linuxppc-dev@lists.ozlabs.org, "David S. Miller" Date: Fri, 20 Jun 2014 10:37:26 +1000 In-Reply-To: <53A2C78D.9060708@hitachi.com> References: <5387F150.5000307@hitachi.com> <20140530031838.17427.75896.stgit@ltc230.yrl.intra.hitachi.co.jp> <539161D6.7020508@hitachi.com> <1403078179.32307.7.camel@concordia> <53A15201.7060404@hitachi.com> <1403141433.4768.1.camel@concordia> <53A26C99.6060000@hitachi.com> <53A285D0.1030106@in.ibm.com> <53A2908E.2000806@hitachi.com> <53A2B136.108@in.ibm.com> <53A2C315.9030006@hitachi.com> <53A2C78D.9060708@hitachi.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4-0ubuntu1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2014-06-19 at 20:20 +0900, Masami Hiramatsu wrote: > (2014/06/19 20:01), Masami Hiramatsu wrote: > > >>>>> Ah, those messages should be shown in dmesg when booting if it doesn't work, > >>>>> because the messages are printed by initialization process of kprobe blacklist. > >>>>> So, reproducing it is just enabling CONFIG_KPROBES and boot it. > >>>> Well, we don't get those messages on Power, since the kallsyms has the > >>>> entries for ".function_name". The correct way to verify is, either : > >>> > >>> Hmm, that seems another issue on powerpc. Is that expected(and designed) > >>> behavior? > >> AFAIK, yes, it is. > >> To be more precise : > >> > >> we have 'foo' and '.foo' for a function foo(), where 'foo' points to the > >> function_entry and '.foo' points to the actual function. > > > > Ah, I see. So if we run > > > > func_ptr p = foo; > > return p == kallsyms_lookup_name(".foo"); > > > > it returns true. > > One more thing I should know, is the address of ".function_name" within the > kernel text? In other words, does kernel_text_address() return true for that > address? If not, it's easy to verify the address. Yes. That is the text address, kernel_text_address() should definitely return true. On 64-bit, ABIv1, "foo" points to the function descriptor, in the ".opd" section. ".foo" points to the actual text of the function, in ".text". On 64-bit, ABIv2, "foo" points to the text in ".text". There are no dot symbols. cheers -- 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/