Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932561AbaFTCN0 (ORCPT ); Thu, 19 Jun 2014 22:13:26 -0400 Received: from mail4.hitachi.co.jp ([133.145.228.5]:35600 "EHLO mail4.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757338AbaFTCNY (ORCPT ); Thu, 19 Jun 2014 22:13:24 -0400 Message-ID: <53A398BB.2010909@hitachi.com> Date: Fri, 20 Jun 2014 11:13:15 +0900 From: Masami Hiramatsu Organization: Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Michael Ellerman 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" Subject: Re: [RFT PATCH -next v3] [BUGFIX] kprobes: Fix "Failed to find blacklist" error on ia64 and ppc64 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> <1403224646.18509.1.camel@concordia> In-Reply-To: <1403224646.18509.1.camel@concordia> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2014/06/20 9:37), Michael Ellerman wrote: > 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". Hmm, I misunderstood that. Anyway, we can verify it by kernel_text_address(). > > On 64-bit, ABIv2, "foo" points to the text in ".text". There are no dot > symbols. OK, in that case, kernel_text_address() check is still available. :) Thank you, -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com -- 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/