(2015/01/20 12:02), Wang Nan wrote:
> On 2015/1/12 19:24, Masami Hiramatsu wrote:
>> (2015/01/05 21:31), Wang Nan wrote:
>>> In original code, the probed instruction doesn't get optimized after
>>>
>>> echo 0 > /sys/kernel/debug/kprobes/enabled
>>> echo 1 > /sys/kernel/debug/kprobes/enabled
>>>
>>> This is because original code checks kprobes_all_disarmed in
>>> optimize_kprobe(), but this flag is turned off after calling that
>>> function. Therefore, optimize_kprobe() will see
>>> kprobes_all_disarmed == true and doesn't do the optimization.
>>
>> OK, a workaround is to disable/enable optimizing via sysctl.
>>
>>>
>>> This patch simply turns off kprobes_all_disarmed earlier to enable
>>> optimization.
>>>
>>
>> Anyway, thank you for finding that! :)
>>
>> Acked-by: Masami Hiramatsu <masami.hiramatsu...@hitachi.com>
>>
>
> Hi Masami Hiramatsu,
>
> What about this patch? Are you still thinking on it like
> '[PATCH] kprobes: bugfix: checks kprobes_all_disarmed in
> unoptimized_kprobe()' ?
Without this patch.
-----
[root@localhost tracing]# echo p do_fork+5 > kprobe_events
[root@localhost tracing]# echo 1 > events/kprobes/p_do_fork_5/enable
[root@localhost tracing]# cat ../kprobes/list
ffffffff810bd055 k do_fork+0x5 [OPTIMIZED]
[root@localhost tracing]# echo 0 > /sys/kernel/debug/kprobes/enabled
[root@localhost tracing]# cat ../kprobes/list
ffffffff810bd055 k do_fork+0x5
[root@localhost tracing]# echo 1 > /sys/kernel/debug/kprobes/enabled
[root@localhost tracing]# cat ../kprobes/list
ffffffff810bd055 k do_fork+0x5
------
With this patch.
------
[root@localhost tracing]# echo p do_fork+5 > kprobe_events
[root@localhost tracing]# echo 1 > events/kprobes/enable
[root@localhost tracing]# cat ../kprobes/list
ffffffff810bc1c5 k do_fork+0x5 [OPTIMIZED]
[root@localhost tracing]# echo 0 > ../kprobes/enabled
[root@localhost tracing]# cat ../kprobes/list
ffffffff810bc1c5 k do_fork+0x5
[root@localhost tracing]# echo 1 > ../kprobes/enabled
[root@localhost tracing]# cat ../kprobes/list
ffffffff810bc1c5 k do_fork+0x5 [OPTIMIZED]
------
So, looks OK to me too ;)
Acked-by: Masami Hiramatsu <masami.hiramatsu...@hitachi.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu...@hitachi.com>
Ingo,
Could you also pull this patch to your -tip tree?
Thank you,
>
> Thank you.
>
>>
>>> Signed-off-by: Wang Nan <wangn...@huawei.com>
>>> ---
>>> kernel/kprobes.c | 7 ++++++-
>>> 1 file changed, 6 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
>>> index bad4e95..b185464 100644
>>> --- a/kernel/kprobes.c
>>> +++ b/kernel/kprobes.c
>>> @@ -2320,6 +2320,12 @@ static void arm_all_kprobes(void)
>>> if (!kprobes_all_disarmed)
>>> goto already_enabled;
>>>
>>> + /*
>>> + * optimize_kprobe() called by arm_kprobe() checks
>>> + * kprobes_all_disarmed, so set kprobes_all_disarmed before
>>> + * arm_kprobe.
>>> + */
>>> + kprobes_all_disarmed = false;
>>> /* Arming kprobes doesn't optimize kprobe itself */
>>> for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
>>> head = &kprobe_table[i];
>>> @@ -2328,7 +2334,6 @@ static void arm_all_kprobes(void)
>>> arm_kprobe(p);
>>> }
>>>
>>> - kprobes_all_disarmed = false;
>>> printk(KERN_INFO "Kprobes globally enabled\n");
>>>
>>> already_enabled:
>>>
>>
>>
>
>
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--
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu...@hitachi.com
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