From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> To: Wang Nan <wangnan0@huawei.com> 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: force unoptimize when disable kprobes. Date: Mon, 12 Jan 2015 20:42:38 +0900 [thread overview] Message-ID: <54B3B32E.7070709@hitachi.com> (raw) In-Reply-To: <1420461140-27153-1-git-send-email-wangnan0@huawei.com> (2015/01/05 21:32), Wang Nan wrote: > Original code failed to disarm the probed instruction after > > echo 0 > /sys/kernel/debug/kprobes/enabled > > if OPTPROBE is enabled. > > This is caused by a piece of logically inconsistent code: > > unoptimize_kprobe(p, false); > if (!kprobe_queued(p)) { > ... > } > > unoptimize_kprobe() with 'force' == false queues p onto > unoptimizing_list, so following kprobe_queued() check always fail unless > another core schedules optimizer and does the unoptimization very soon. > This logic causes arch_disarm_kprobe() failed to get execute, lefts a > breakpoint at the probed address, instead of restoring it. No, the root cause of this failure comes from the lack of checking kprobes_all_disarmed in unoptimized_kprobe(). It should check the flag and return soon if it is set. So, I Nak this patch. > > This patch uses force unoptimize instead. > > Signed-off-by: Wang Nan <wangnan0@huawei.com> > --- > kernel/kprobes.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index b185464..9fbe0c3 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -869,7 +869,7 @@ static void __disarm_kprobe(struct kprobe *p, bool reopt) > { > struct kprobe *_p; > > - unoptimize_kprobe(p, false); /* Try to unoptimize */ > + unoptimize_kprobe(p, true); /* Try to unoptimize */ > > if (!kprobe_queued(p)) { > arch_disarm_kprobe(p); > -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com
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From: masami.hiramatsu.pt@hitachi.com (Masami Hiramatsu) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH] kprobes: bugfix: force unoptimize when disable kprobes. Date: Mon, 12 Jan 2015 20:42:38 +0900 [thread overview] Message-ID: <54B3B32E.7070709@hitachi.com> (raw) In-Reply-To: <1420461140-27153-1-git-send-email-wangnan0@huawei.com> (2015/01/05 21:32), Wang Nan wrote: > Original code failed to disarm the probed instruction after > > echo 0 > /sys/kernel/debug/kprobes/enabled > > if OPTPROBE is enabled. > > This is caused by a piece of logically inconsistent code: > > unoptimize_kprobe(p, false); > if (!kprobe_queued(p)) { > ... > } > > unoptimize_kprobe() with 'force' == false queues p onto > unoptimizing_list, so following kprobe_queued() check always fail unless > another core schedules optimizer and does the unoptimization very soon. > This logic causes arch_disarm_kprobe() failed to get execute, lefts a > breakpoint at the probed address, instead of restoring it. No, the root cause of this failure comes from the lack of checking kprobes_all_disarmed in unoptimized_kprobe(). It should check the flag and return soon if it is set. So, I Nak this patch. > > This patch uses force unoptimize instead. > > Signed-off-by: Wang Nan <wangnan0@huawei.com> > --- > kernel/kprobes.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index b185464..9fbe0c3 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -869,7 +869,7 @@ static void __disarm_kprobe(struct kprobe *p, bool reopt) > { > struct kprobe *_p; > > - unoptimize_kprobe(p, false); /* Try to unoptimize */ > + unoptimize_kprobe(p, true); /* Try to unoptimize */ > > if (!kprobe_queued(p)) { > arch_disarm_kprobe(p); > -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt at hitachi.com
next prev parent reply other threads:[~2015-01-12 11:42 UTC|newest] Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-01-05 12:32 [PATCH] kprobes: bugfix: force unoptimize when disable kprobes Wang Nan 2015-01-05 12:32 ` Wang Nan 2015-01-12 11:42 ` Masami Hiramatsu [this message] 2015-01-12 11:42 ` Masami Hiramatsu 2015-01-12 12:09 ` [PATCH] kprobes: bugfix: checks kprobes_all_disarmed in unoptimized_kprobe() Wang Nan 2015-01-12 12:09 ` Wang Nan 2015-01-12 12:52 ` Masami Hiramatsu 2015-01-12 12:52 ` Masami Hiramatsu 2015-01-19 3:04 ` Wang Nan 2015-01-19 3:04 ` Wang Nan 2015-01-19 9:05 ` Masami Hiramatsu 2015-01-19 9:05 ` Masami Hiramatsu 2015-01-19 11:21 ` Wang Nan 2015-01-19 11:21 ` Wang Nan 2015-01-19 12:45 ` Masami Hiramatsu 2015-01-19 12:45 ` Masami Hiramatsu 2015-01-19 12:59 ` Wang Nan 2015-01-19 12:59 ` Wang Nan 2015-01-20 2:51 ` [PATCH] kprobes: bugfix: makes kprobes/enabled works correctly for optimized kprobes Wang Nan 2015-01-20 2:51 ` Wang Nan 2015-01-20 7:12 ` Masami Hiramatsu 2015-01-20 7:12 ` Masami Hiramatsu
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