Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756906AbaFSGl5 (ORCPT ); Thu, 19 Jun 2014 02:41:57 -0400 Received: from e23smtp03.au.ibm.com ([202.81.31.145]:60263 "EHLO e23smtp03.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753082AbaFSGlz (ORCPT ); Thu, 19 Jun 2014 02:41:55 -0400 Message-ID: <53A285D0.1030106@in.ibm.com> Date: Thu, 19 Jun 2014 12:10:16 +0530 From: "Suzuki K. Poulose" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Masami Hiramatsu , Michael Ellerman CC: 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> In-Reply-To: <53A26C99.6060000@hitachi.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14061906-6102-0000-0000-000005CFE870 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/19/2014 10:22 AM, Masami Hiramatsu wrote: > (2014/06/19 10:30), Michael Ellerman wrote: >> On Wed, 2014-06-18 at 17:46 +0900, Masami Hiramatsu wrote: >>> (2014/06/18 16:56), Michael Ellerman wrote: >>>> On Fri, 2014-06-06 at 15:38 +0900, Masami Hiramatsu wrote: >>>>> Ping? >>>>> >>>>> I guess this should go to 3.16 branch, shouldn't it? >>>> >>>>>> diff --git a/arch/powerpc/include/asm/types.h b/arch/powerpc/include/asm/types.h >>>>>> index bfb6ded..8b89d65 100644 >>>>>> --- a/arch/powerpc/include/asm/types.h >>>>>> +++ b/arch/powerpc/include/asm/types.h >>>>>> @@ -25,6 +25,17 @@ typedef struct { >>>>>> unsigned long env; >>>>>> } func_descr_t; >>>>>> >>>>>> +#if defined(CONFIG_PPC64) && (!defined(_CALL_ELF) || _CALL_ELF == 1) >>>>>> +/* >>>>>> + * On PPC64 ABIv1 the function pointer actually points to the >>>>>> + * function's descriptor. The first entry in the descriptor is the >>>>>> + * address of the function text. >>>>>> + */ >>>>>> +#define function_entry(fn) (((func_descr_t *)(fn))->entry) >>>>>> +#else >>>>>> +#define function_entry(fn) ((unsigned long)(fn)) >>>>>> +#endif >>>> >>>> We already have ppc_function_entry(), can't you use that? >>> >>> I'd like to ask you whether the address which ppc_function_entry() returns on >>> PPC ABIv2 is really same address in kallsyms or not. >>> As you can see, kprobes uses function_entry() to get the actual entry address >>> where kallsyms knows. I have not much information about that, but it seems that >>> the "global entry point" is the address which kallsyms knows, isn't it? >> >> OK. I'm not sure off the top of my head which address kallsyms knows about, but >> yes it's likely that it is the global entry point. >> >> I recently sent a patch to add ppc_global_function_entry(), because we need it >> in the ftrace code. Once that is merged you could use that. > > Yeah, I could use that. But since this is used in arch-independent code (e.g. IA64 > needs similar macro), I think we'd better define function_entry() in asm/types.h for > general use (for kallsyms), and rename ppc_function_entry to local_function_entry() > in asm/code-patching.h. > > >> How do you hit the original problem, you don't actually specify in your commit >> message? Something with kprobes obviously, but what exactly? I'll try and >> reproduce it here. > > 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 : 1) Dump the black_list via xmon ( see : https://lkml.org/lkml/2014/5/29/893 ) and verify the entries. or 2) Issue a kprobe on a black listed entry and hit a success,(which we will, since we don't check the actual function address). Thanks Suzuki > > Thank you, > -- 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/