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From: Wang Nan <wangnan0@huawei.com>
To: <masami.hiramatsu.pt@hitachi.com>, <tixy@linaro.org>,
	<linux@arm.linux.org.uk>
Cc: <linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>, <lizefan@huawei.com>
Subject: [PATCH] kprobes: bugfix: force unoptimize when disable kprobes.
Date: Mon, 5 Jan 2015 20:32:20 +0800	[thread overview]
Message-ID: <1420461140-27153-1-git-send-email-wangnan0@huawei.com> (raw)

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.

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);
-- 
1.8.4


WARNING: multiple messages have this Message-ID (diff)
From: wangnan0@huawei.com (Wang Nan)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] kprobes: bugfix: force unoptimize when disable kprobes.
Date: Mon, 5 Jan 2015 20:32:20 +0800	[thread overview]
Message-ID: <1420461140-27153-1-git-send-email-wangnan0@huawei.com> (raw)

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.

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);
-- 
1.8.4

             reply	other threads:[~2015-01-05 12:38 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-05 12:32 Wang Nan [this message]
2015-01-05 12:32 ` [PATCH] kprobes: bugfix: force unoptimize when disable kprobes Wang Nan
2015-01-12 11:42 ` Masami Hiramatsu
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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