On Tue, Sep 05, 2023 at 10:23:27AM +0800, Hou Tao wrote:
> Hi,
>
> On 8/28/2023 3:55 PM, Jiri Olsa wrote:
> > Add missed value to kprobe attached through perf link info to
> > hold the stats of missed kprobe handler execution.
> >
> > The kprobe's missed counter gets incremented when kprobe handler
> > is not executed due to another kprobe running on the same cpu.
> >
> > Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> > ---
> > include/linux/trace_events.h | 6 ++++--
> > include/uapi/linux/bpf.h | 1 +
> > kernel/bpf/syscall.c | 14 ++++++++------
> > kernel/trace/bpf_trace.c | 5 +++--
> > kernel/trace/trace_kprobe.c | 5 ++++-
> > tools/include/uapi/linux/bpf.h | 1 +
> > 6 files changed, 21 insertions(+), 11 deletions(-)
> >
>
> SNIP
> > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> > index 17c21c0b2dd1..998c88874507 100644
> > --- a/kernel/trace/trace_kprobe.c
> > +++ b/kernel/trace/trace_kprobe.c
> > @@ -1546,7 +1546,8 @@ NOKPROBE_SYMBOL(kretprobe_perf_func);
> >
> > int bpf_get_kprobe_info(const struct perf_event *event, u32 *fd_type,
> > const char **symbol, u64 *probe_offset,
> > - u64 *probe_addr, bool perf_type_tracepoint)
> > + u64 *probe_addr, unsigned long *missed,
> > + bool perf_type_tracepoint)
> > {
> > const char *pevent = trace_event_name(event->tp_event);
> > const char *group = event->tp_event->class->system;
> > @@ -1565,6 +1566,8 @@ int bpf_get_kprobe_info(const struct perf_event *event, u32 *fd_type,
> > *probe_addr = kallsyms_show_value(current_cred()) ?
> > (unsigned long)tk->rp.kp.addr : 0;
> > *symbol = tk->symbol;
> > + if (missed)
> > + *missed = tk->rp.kp.nmissed;
>
> According to the implement of probes_profile_seq_show(), the missed
> counter for kretprobe should be tk->rp.kp.nmissed + tk->rp.nmissed. I
> think it would be a good idea to factor out a common helper to get the
> missed counter for kprobe or kretprobe.
ok, makes sense.. will check, I was also thinking to move
bpf_get_kprobe_info args into struct
jirka
> > return 0;
> > }
> > #endif /* CONFIG_PERF_EVENTS */
> > diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> > index b754edfb0cd7..5a39c7a13499 100644
> > --- a/tools/include/uapi/linux/bpf.h
> > +++ b/tools/include/uapi/linux/bpf.h
> > @@ -6539,6 +6539,7 @@ struct bpf_link_info {
> > __u32 name_len;
> > __u32 offset; /* offset from func_name */
> > __u64 addr;
> > + __u64 missed;
> > } kprobe; /* BPF_PERF_EVENT_KPROBE, BPF_PERF_EVENT_KRETPROBE */
> > struct {
> > __aligned_u64 tp_name; /* in/out */
>
