(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
810bc1c5 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...@hitachi.com
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