From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752459AbbATHM1 (ORCPT ); Tue, 20 Jan 2015 02:12:27 -0500 Received: from mail9.hitachi.co.jp ([133.145.228.44]:50428 "EHLO mail9.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752274AbbATHMW (ORCPT ); Tue, 20 Jan 2015 02:12:22 -0500 Message-ID: <54BDFFCD.6070303@hitachi.com> Date: Tue, 20 Jan 2015 16:12:13 +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: Wang Nan , Ingo Molnar Cc: tixy@linaro.org, linux@arm.linux.org.uk, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, lizefan@huawei.com Subject: Re: [PATCH] kprobes: bugfix: makes kprobes/enabled works correctly for optimized kprobes. References: <54BCFC6E.1080007@hitachi.com> <1421722311-30455-1-git-send-email-wangnan0@huawei.com> In-Reply-To: <1421722311-30455-1-git-send-email-wangnan0@huawei.com> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2015/01/20 11:51), Wang Nan wrote: > debugfs/kprobes/enabled doesn't work correctly on optimized kprobes. > Masami Hiramatsu has a test report on x86_64 platform: > > https://lkml.org/lkml/2015/1/19/274 > > This patch forces it to unoptimize kprobe if kprobes_all_disarmed > is set. It also checks the flag in unregistering path for skipping > unneeded disarming process when kprobes globally disarmed. > OK, here is the test result. ---- [root@localhost tracing]# echo p do_fork+5 > kprobe_events [root@localhost tracing]# echo $$ > set_ftrace_pid [root@localhost tracing]# echo 1 > events/kprobes/p_do_fork_5/enable [root@localhost tracing]# cat trace # tracer: nop # # entries-in-buffer/entries-written: 1/1 #P:8 # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / delay # TASK-PID CPU# |||| TIMESTAMP FUNCTION # | | | |||| | | bash-11466 [004] d... 4548.420463: p_do_fork_5: (do_fork+0x5/0x360) [root@localhost tracing]# cat ../kprobes/list ffffffff810bc1c5 k do_fork+0x5 [OPTIMIZED] [root@localhost tracing]# echo 0 > ../kprobes/enabled # kprobes globally disabled [root@localhost tracing]# echo > trace # clear trace buffer [root@localhost tracing]# cat trace # tracer: nop # # entries-in-buffer/entries-written: 0/0 #P:8 # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / delay # TASK-PID CPU# |||| TIMESTAMP FUNCTION # | | | |||| | | # No event traced! [root@localhost tracing]# echo 0 > events/kprobes/p_do_fork_5/enable [root@localhost tracing]# echo > kprobe_events [root@localhost tracing]# cat ../kprobes/list [root@localhost tracing]# # And we can safely remove the probe ----- Now it looks good to me :) Acked-by: Masami Hiramatsu Tested-by: Masami Hiramatsu Ingo, Could you pull this patch to your -tip tree? Thank you, > Signed-off-by: Wang Nan > --- > kernel/kprobes.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index 9471710..fb995ef 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -869,7 +869,8 @@ static void __disarm_kprobe(struct kprobe *p, bool reopt) > { > struct kprobe *_p; > > - unoptimize_kprobe(p, false); /* Try to unoptimize */ > + /* Try to unoptimize */ > + unoptimize_kprobe(p, kprobes_all_disarmed); > > if (!kprobe_queued(p)) { > arch_disarm_kprobe(p); > @@ -1571,7 +1572,13 @@ static struct kprobe *__disable_kprobe(struct kprobe *p) > > /* Try to disarm and disable this/parent probe */ > if (p == orig_p || aggr_kprobe_disabled(orig_p)) { > - disarm_kprobe(orig_p, true); > + /* > + * If kprobes_all_disarmed is set, orig_p > + * should have already been disarmed, so > + * skip unneed disarming process. > + */ > + if (!kprobes_all_disarmed) > + disarm_kprobe(orig_p, true); > orig_p->flags |= KPROBE_FLAG_DISABLED; > } > } > -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com