Re: [PATCH bpf-next 1/2] bpf: Add show_fdinfo for uprobe_multi

[Tao Chen]

在 2025/6/13 05:27, Andrii Nakryiko 写道:
> On Thu, Jun 12, 2025 at 4:56 AM Tao Chen <chen.dylane@xxxxxxxxx> wrote:
> > Show uprobe_multi link info with fdinfo, the info as follows:
> >
> > link_type:      uprobe_multi
> > link_id:        9
> > prog_tag:       e729f789e34a8eca
> > prog_id:        39
> > type:   uprobe_multi
> > func_cnt:       3
> > pid:    0
> > path:   /home/dylane/bpf/tools/testing/selftests/bpf/test_progs
> > offset: 0xa69ed7
> > ref_ctr_offset: 0x0
> > cookie: 3
> > offset: 0xa69ee2
> > ref_ctr_offset: 0x0
> > cookie: 1
> > offset: 0xa69eed
> > ref_ctr_offset: 0x0
> > cookie: 2
> >
> > Signed-off-by: Tao Chen <chen.dylane@xxxxxxxxx>
> > ---
> >   kernel/trace/bpf_trace.c | 48 ++++++++++++++++++++++++++++++++++++++++
> >   1 file changed, 48 insertions(+)
> >
> > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> > index 24b94870b50..c4ad82b8fd8 100644
> > --- a/kernel/trace/bpf_trace.c
> > +++ b/kernel/trace/bpf_trace.c
> > @@ -3157,10 +3157,58 @@ static int bpf_uprobe_multi_link_fill_link_info(const struct bpf_link *link,
> >          return err;
> >   }
> >
> > +#ifdef CONFIG_PROC_FS
> > +static void bpf_uprobe_multi_show_fdinfo(const struct bpf_link *link,
> > +                                        struct seq_file *seq)
> > +{
> > +       struct bpf_uprobe_multi_link *umulti_link;
> > +       char *p, *buf;
> > +
> > +       umulti_link = container_of(link, struct bpf_uprobe_multi_link, link);
> > +
> > +       buf = kmalloc(PATH_MAX, GFP_KERNEL);
> > +       if (!buf)
> > +               return;
> > +
> > +       p = d_path(&umulti_link->path, buf, PATH_MAX);
> > +       if (IS_ERR(p)) {
> > +               kfree(buf);
> > +               return;
> > +       }
> > +
> > +       seq_printf(seq,
> > +                  "type:\t%s\n"
> > +                  "func_cnt:\t%u\n"
>
> it's not really *func* (e.g., for USDTs it's basically guaranteed to
> be somewhere inside the function, potentially in many places within
> the same function), I'd use generic "uprobe_{cnt,count}"

will change it in v2, thanks for the advice.

> > +                  "pid:\t%u\n"
> > +                  "path:\t%s\n",
> > +                  umulti_link->flags == BPF_F_UPROBE_MULTI_RETURN ?
> > +                                        "uretprobe_multi" : "uprobe_multi",
> > +                  umulti_link->cnt,
> > +                  umulti_link->task ? task_pid_nr_ns(umulti_link->task,
> > +                          task_active_pid_ns(current)) : 0,
> > +                  p);
> > +
> > +       for (int i = 0; i < umulti_link->cnt; i++) {
> > +               seq_printf(seq,
> > +                          "offset:\t%#llx\n"
> > +                          "ref_ctr_offset:\t%#lx\n"
> > +                          "cookie:\t%llu\n",
> > +                          umulti_link->uprobes[i].offset,
> > +                          umulti_link->uprobes[i].ref_ctr_offset,
> > +                          umulti_link->uprobes[i].cookie);
> > +       }
> > +
> > +       kfree(buf);
> > +}
> > +#endif
> > +
> >   static const struct bpf_link_ops bpf_uprobe_multi_link_lops = {
> >          .release = bpf_uprobe_multi_link_release,
> >          .dealloc_deferred = bpf_uprobe_multi_link_dealloc,
> >          .fill_link_info = bpf_uprobe_multi_link_fill_link_info,
> > +#ifdef CONFIG_PROC_FS
> > +       .show_fdinfo = bpf_uprobe_multi_show_fdinfo,
> > +#endif
> >   };
> >
> >   static int uprobe_prog_run(struct bpf_uprobe *uprobe,
> > --
> > 2.48.1


--
Best Regards
Tao Chen