On Thu, Jun 12, 2025 at 4:56 AM Tao Chen <chen.dyl...@linux.dev> 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.dyl...@linux.dev>
> ---
> 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}"
> + "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
>
