From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934760AbaEFKEH (ORCPT ); Tue, 6 May 2014 06:04:07 -0400 Received: from mail9.hitachi.co.jp ([133.145.228.44]:53670 "EHLO mail9.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934558AbaEFKEE (ORCPT ); Tue, 6 May 2014 06:04:04 -0400 Message-ID: <5368B38B.5080908@hitachi.com> Date: Tue, 06 May 2014 19:03:55 +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: Tony Luck Cc: Ingo Molnar , Linus Torvalds , Rusty Russell , rdunlap@infradead.org, Jeremy Fitzhardinge , Arnd Bergmann , dl9pf@gmx.de, Andrew Morton , sparse@chrisli.org, Thomas Gleixner , "H. Peter Anvin" , Linux Kernel Mailing List , anil.s.keshavamurthy@intel.com, "David S. Miller" , "ananth@in.ibm.com" , Chris Wright , akataria@vmware.com, linux-tip-commits@vger.kernel.org, "yrl.pp-manager.tt@hitachi.com" Subject: Re: [tip:perf/kprobes] kprobes: Introduce NOKPROBE_SYMBOL() macro to maintain kprobes blacklist References: <20140417081705.26341.96719.stgit@ltc230.yrl.intra.hitachi.co.jp> In-Reply-To: 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 (2014/05/06 5:48), Tony Luck wrote: > This patch is in linux-next ("next-20140505") and I see a > bunch of "Failed to find blacklist" messages when booting > on ia64: > > Failed to find blacklist 0001013168300000 > Failed to find blacklist 0001013000f0a000 > Failed to find blacklist 000101315f70a000 > Failed to find blacklist 000101324c80a000 > Failed to find blacklist 0001013063f0a000 > Failed to find blacklist 000101327800a000 > Failed to find blacklist 0001013277f0a000 > Failed to find blacklist 000101315a70a000 > Failed to find blacklist 0001013277e0a000 > Failed to find blacklist 000101305a20a000 > Failed to find blacklist 0001013277d0a000 > Failed to find blacklist 00010130bdc0a000 > Failed to find blacklist 00010130dc20a000 > Failed to find blacklist 000101309a00a000 > Failed to find blacklist 0001013277c0a000 > Failed to find blacklist 0001013277b0a000 > Failed to find blacklist 0001013277a0a000 > Failed to find blacklist 000101327790a000 > Failed to find blacklist 000101303140a000 > Failed to find blacklist 0001013a3280a000 > > What do these mean? Ah, I forgot that ia64 has function descriptor :( That means kprobes initial code has failed to get correct entry address of the blacklisted functions. In include/linux/kprobes.h, I defined NOKPROBE_SYMBOL to store the addresses of blacklisted functions as below, #define __NOKPROBE_SYMBOL(fname) \ static unsigned long __used \ __attribute__((section("_kprobe_blacklist"))) \ _kbl_addr_##fname = (unsigned long)fname; #define NOKPROBE_SYMBOL(fname) __NOKPROBE_SYMBOL(fname) _kbl_addr_XX stores the address of the function, but on IA64, it stores the address of function descriptor. Since those addresses are only used with kallsyms to lookup function size, I think I should use a macro to store correct function address instead of the address of function descriptor on ia64 (and similar arch). But I'm not sure which macro I should use... Is there any good way to get the address of function, instead of function descriptor? Thank you, -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com