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SubjectRe: [PATCH] kprobes: bugfix: set kprobes_all_disarmed earlier to enable re-optimization.
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.pt@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()' ?

Thank you.

>
>> Signed-off-by: Wang Nan <wangnan0@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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