From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755481Ab3KVLqW (ORCPT ); Fri, 22 Nov 2013 06:46:22 -0500 Received: from mail7.hitachi.co.jp ([133.145.228.42]:47705 "EHLO mail7.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752565Ab3KVLqU (ORCPT ); Fri, 22 Nov 2013 06:46:20 -0500 Message-ID: <528F4406.3090309@hitachi.com> Date: Fri, 22 Nov 2013 20:46:14 +0900 From: Masami Hiramatsu Organization: Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows NT 5.2; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Ingo Molnar Cc: "Frank Ch. Eigler" , linux-arch@vger.kernel.org, Ananth N Mavinakayanahalli , Sandeepa Prabhu , x86@kernel.org, lkml , "Steven Rostedt (Red Hat)" , virtualization@lists.linux-foundation.org, systemtap@sourceware.org, "David S. Miller" Subject: Re: Re: Re: [PATCH -tip v3 00/23] kprobes: introduce NOKPROBE_SYMBOL() and general cleaning of kprobe blacklist References: <20131120042148.15296.88360.stgit@kbuild-fedora.novalocal> <20131120153801.GA9743@gmail.com> <20131120173600.GK8993@redhat.com> <528D6C9F.8050809@hitachi.com> <20131121072938.GA16912@gmail.com> <528EC2FF.30301@hitachi.com> In-Reply-To: <528EC2FF.30301@hitachi.com> 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 (2013/11/22 11:35), Masami Hiramatsu wrote: > (2013/11/21 16:29), Ingo Molnar wrote: >> >> * Masami Hiramatsu wrote: >> >>> (2013/11/21 2:36), Frank Ch. Eigler wrote: >> >> [ ... ] >>>> one needs to resort to something like: >>>> >>>> # cat /proc/kallsyms | grep ' [tT] ' | while read addr type symbol; do >>>> perf probe $symbol >>>> done >>>> >>>> then wait for a few hours for that to finish. Then, or while the loop >>>> is still running, run >>>> >>>> # perf record -e 'probe:*' -aR sleep 1 >>>> >>>> to take a kernel down. >>> >>> Um, indeed, current blacklist is not perfect. [...] >> >> Then it needs to be fixed ASAP! > > OK, I see. At least the two patches included this series > should be fixed. :) > > And more, I need to test all symbols and drills down. OK, what I've found was; - The functions which can be ftraced look good. (see tracing/available_filter_functions) - following functions should not be able to be probed. - memcpy, memset - native_load_sp0 and some other native functions (need to be clear) - restore - trace_graph_return - trace_hardirqs_off_thunk, trace_hardirqs_on_thunk - This list still be not perfect. I just enabled/disabled kprobes one by one. There might be combined bugs (combination of several kprobes). - Some of them are hard to specify by NOKPROBE_SYMBOL because they are defined in assembly file. Anyway, to fix all of them, I think we need file-based blacklist especially for assembler symbols. For example, we can get all text symbols by below command; nm some-file.o | grep -i " t " | cut -f3 -d" " so that we can make a blacklisted-symbol list for the file. I need to look the Kbuild for how I can do that in Makefile. Thank you, -- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com