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Date: Tue, 6 Sep 2022 11:12:14 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Jianlin Lv <iecedge@...il.com>
Cc: corbet@....net, mingo@...hat.com, jianlv@...y.com,
linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
Masami Hiramatsu <mhiramat@...nel.org>,
Tom Zanussi <zanussi@...nel.org>
Subject: Re: [PATCH v2] tracing/kprobes: Add method to display private
kprobes in tracefs
[ Adding Masami and Tom ]
On Mon, 25 Jul 2022 06:23:34 +0000
Jianlin Lv <iecedge@...il.com> wrote:
> The private kprobes are not added to the global list dyn_event_list,
> so there is a missing interface to show probe hit and probe miss.
> This patch adds a profiling interface to check the number of hits or
> misses for private kprobes.
Masami, what do you think of this patch?
-- Steve
>
> Signed-off-by: Jianlin Lv <iecedge@...il.com>
> ---
> v2: update commit message
> ---
> Documentation/trace/kprobetrace.rst | 6 +++-
> kernel/trace/trace_dynevent.c | 20 +++++++++++
> kernel/trace/trace_dynevent.h | 37 ++++++++++++++++++++
> kernel/trace/trace_kprobe.c | 54 +++++++++++++++++++++++++++++
> 4 files changed, 116 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/trace/kprobetrace.rst b/Documentation/trace/kprobetrace.rst
> index b175d88f31eb..8815d64dd8a6 100644
> --- a/Documentation/trace/kprobetrace.rst
> +++ b/Documentation/trace/kprobetrace.rst
> @@ -146,7 +146,11 @@ trigger:
> Event Profiling
> ---------------
> You can check the total number of probe hits and probe miss-hits via
> -/sys/kernel/debug/tracing/kprobe_profile.
> +/sys/kernel/debug/tracing/kprobe_profile or
> +/sys/kernel/debug/tracing/kprobe_local_profile.
> +All kprobe events created by kprobe_events will be added to the global
> +list, you can get their profiling via kprobe_profile; kprobe_local_profile
> +shows profiling for private kprobe events created by perf_kprobe pmu.
> The first column is event name, the second is the number of probe hits,
> the third is the number of probe miss-hits.
>
> diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
> index 076b447a1b88..70ec99cd9c53 100644
> --- a/kernel/trace/trace_dynevent.c
> +++ b/kernel/trace/trace_dynevent.c
> @@ -181,6 +181,26 @@ static const struct seq_operations dyn_event_seq_op = {
> .show = dyn_event_seq_show
> };
>
> +#ifdef CONFIG_KPROBE_EVENTS
> +LIST_HEAD(local_event_list);
> +
> +void *local_event_seq_start(struct seq_file *m, loff_t *pos)
> +{
> + mutex_lock(&event_mutex);
> + return seq_list_start(&local_event_list, *pos);
> +}
> +
> +void *local_event_seq_next(struct seq_file *m, void *v, loff_t *pos)
> +{
> + return seq_list_next(v, &local_event_list, pos);
> +}
> +
> +void local_event_seq_stop(struct seq_file *m, void *v)
> +{
> + mutex_unlock(&event_mutex);
> +}
> +#endif /* CONFIG_KPROBE_EVENTS */
> +
> /*
> * dyn_events_release_all - Release all specific events
> * @type: the dyn_event_operations * which filters releasing events
> diff --git a/kernel/trace/trace_dynevent.h b/kernel/trace/trace_dynevent.h
> index 936477a111d3..e30193470295 100644
> --- a/kernel/trace/trace_dynevent.h
> +++ b/kernel/trace/trace_dynevent.h
> @@ -101,6 +101,43 @@ void dyn_event_seq_stop(struct seq_file *m, void *v);
> int dyn_events_release_all(struct dyn_event_operations *type);
> int dyn_event_release(const char *raw_command, struct dyn_event_operations *type);
>
> +#ifdef CONFIG_KPROBE_EVENTS
> +extern struct list_head local_event_list;
> +
> +static inline
> +int local_event_init(struct dyn_event *ev, struct dyn_event_operations *ops)
> +{
> + if (!ev || !ops)
> + return -EINVAL;
> +
> + INIT_LIST_HEAD(&ev->list);
> + ev->ops = ops;
> + return 0;
> +}
> +
> +static inline int local_event_add(struct dyn_event *ev)
> +{
> + lockdep_assert_held(&event_mutex);
> +
> + if (!ev || !ev->ops)
> + return -EINVAL;
> +
> + list_add_tail(&ev->list, &local_event_list);
> + return 0;
> +}
> +
> +static inline void local_event_remove(struct dyn_event *ev)
> +{
> + lockdep_assert_held(&event_mutex);
> + list_del_init(&ev->list);
> +}
> +
> +void *local_event_seq_start(struct seq_file *m, loff_t *pos);
> +void *local_event_seq_next(struct seq_file *m, void *v, loff_t *pos);
> +void local_event_seq_stop(struct seq_file *m, void *v);
> +
> +#endif /* CONFIG_KPROBE_EVENTS */
> +
> /*
> * for_each_dyn_event - iterate over the dyn_event list
> * @pos: the struct dyn_event * to use as a loop cursor
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index a245ea673715..76f500b17b46 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -1213,6 +1213,52 @@ static const struct file_operations kprobe_profile_ops = {
> .release = seq_release,
> };
>
> +#ifdef CONFIG_KPROBE_EVENTS
> +/* kprobe Local profile */
> +static int local_probes_profile_seq_show(struct seq_file *m, void *v)
> +{
> + struct dyn_event *ev = v;
> + struct trace_kprobe *tk;
> +
> + if (!is_trace_kprobe(ev))
> + return 0;
> +
> + tk = to_trace_kprobe(ev);
> + seq_printf(m, " %-44s %15lu %15lu\n",
> + trace_probe_name(&tk->tp),
> + trace_kprobe_nhit(tk),
> + tk->rp.kp.nmissed);
> +
> + return 0;
> +}
> +
> +static const struct seq_operations local_profile_seq_op = {
> + .start = local_event_seq_start,
> + .next = local_event_seq_next,
> + .stop = local_event_seq_stop,
> + .show = local_probes_profile_seq_show
> +};
> +
> +static int local_profile_open(struct inode *inode, struct file *file)
> +{
> + int ret;
> +
> + ret = security_locked_down(LOCKDOWN_TRACEFS);
> + if (ret)
> + return ret;
> +
> + return seq_open(file, &local_profile_seq_op);
> +}
> +
> +static const struct file_operations kprobe_local_profile_ops = {
> + .owner = THIS_MODULE,
> + .open = local_profile_open,
> + .read = seq_read,
> + .llseek = seq_lseek,
> + .release = seq_release,
> +};
> +#endif /* CONFIG_KPROBE_EVENTS */
> +
> /* Kprobe specific fetch functions */
>
> /* Return the length of string -- including null terminal byte */
> @@ -1830,6 +1876,7 @@ create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
> if (ret < 0)
> goto error;
>
> + local_event_add(&tk->devent);
> return trace_probe_event_call(&tk->tp);
> error:
> free_trace_kprobe(tk);
> @@ -1849,6 +1896,7 @@ void destroy_local_trace_kprobe(struct trace_event_call *event_call)
> return;
> }
>
> + local_event_remove(&tk->devent);
> __unregister_trace_kprobe(tk);
>
> free_trace_kprobe(tk);
> @@ -1929,6 +1977,12 @@ static __init int init_kprobe_trace(void)
> trace_create_file("kprobe_profile", TRACE_MODE_READ,
> NULL, NULL, &kprobe_profile_ops);
>
> +#ifdef CONFIG_KPROBE_EVENTS
> + /* kprobe Local profile */
> + tracefs_create_file("kprobe_local_profile", TRACE_MODE_READ,
> + NULL, NULL, &kprobe_local_profile_ops);
> +#endif /* CONFIG_KPROBE_EVENTS */
> +
> setup_boot_kprobe_events();
>
> return 0;
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