On Sun, Apr 23, 2023 at 10:37:40PM +0900, Masami Hiramatsu wrote:
> On Sun, 23 Apr 2023 09:41:54 +0200
> Jiri Olsa <olsajiri@xxxxxxxxx> wrote:
>
> > On Thu, Apr 20, 2023 at 08:26:10PM +0900, Masami Hiramatsu (Google) wrote:
> > > From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
> > >
> > > Allow fprobe_event to trace raw tracepoints so that user can trace
> > > tracepoints which don't have traceevent wrappers. This new event is
> > > always available if fprobe event is enabled since the tracepoint is
> > > disabled, trace-event and dynamic event is also not available.
> >
> > I thought of ftrace tracepoints wrappers as standard in distros,
> > could you specify which config options that involves?
>
> Ah, sorry, I'm completely confused you.
>
> ----
> This new event is always available if fprobe event is enabled. If the
> tracepoint is disabled, trace-event and dynamic event including
> fprobe is also not available.
> ----
so this basically adds another way of attaching to tracepoint through ftrace
dynamic_events file interface.. but we can already attach to tracepoints
through ftrace via /sys/kernel/debug/tracing/events/* right?
I'm trying to find out what's the config for which this new way of attaching
tracepoints is useful
thanks,
jirka
>
> >
> > > + if (trace_fprobe_is_tracepoint(tf)) {
> > > + struct tracepoint *tpoint = tf->tpoint;
> > > + unsigned long ip = (unsigned long)tpoint->probestub;
> > > + /*
> > > + * Here, we do 2 steps to enable fprobe on a tracepoint.
> > > + * At first, put __probestub_##TP function on the tracepoint
> > > + * and put a fprobe on the stub function.
> > > + */
> > > + ret = tracepoint_probe_register_prio_may_exist(tpoint,
> > > + tpoint->probestub, NULL, 0);
> > > + if (ret < 0)
> > > + return ret;
> > > + return register_fprobe_ips(&tf->fp, &ip, 1);
> >
> > nice idea
>
> Thanks!
>
>
> >
> > jirka
> >
> > > + }
> > > +
> > > /* TODO: handle filter, nofilter or symbol list */
> > > return register_fprobe(&tf->fp, tf->symbol, NULL);
> > > }
> > > @@ -699,6 +723,12 @@ static void __unregister_trace_fprobe(struct trace_fprobe *tf)
> > > if (trace_fprobe_is_registered(tf)) {
> > > unregister_fprobe(&tf->fp);
> > > memset(&tf->fp, 0, sizeof(tf->fp));
> > > + if (trace_fprobe_is_tracepoint(tf)) {
> > > + tracepoint_probe_unregister(tf->tpoint,
> > > + tf->tpoint->probestub, NULL);
> > > + tf->tpoint = NULL;
> > > + tf->mod = NULL;
> > > + }
> > > }
> > > }
> >
> > SNIP
>
>
> --
> Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
