bpftool: Display cookie for tracing link probe

Display cookie for tracing link probe, in plain mode:

 #bpftool link
5: tracing  prog 34
	prog_type tracing  attach_type trace_fentry
	target_obj_id 1  target_btf_id 60355
	cookie 4503599627370496
	pids test_progs(176)

And in json mode:

 #bpftool link -j | jq
{
    "id": 5,
    "type": "tracing",
    "prog_id": 34,
    "prog_type": "tracing",
    "attach_type": "trace_fentry",
    "target_obj_id": 1,
    "target_btf_id": 60355,
    "cookie": 4503599627370496,
    "pids": [
      {
        "pid": 176,
        "comm": "test_progs"
      }
    ]
 }

Signed-off-by: Tao Chen <chen.dylane@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250606165818.3394397-3-chen.dylane@linux.dev

diff --git a/tools/bpf/bpftool/link.c b/tools/bpf/bpftool/link.c
index cb67ce4eba241894fb5b47fd771fa149878bfae3..03513ffffb79b0232fb4cd5a0b9de8a0845cfa07 100644 (file)
--- a/tools/bpf/bpftool/link.c
+++ b/tools/bpf/bpftool/link.c
@@ -503,6 +503,7 @@ static int show_link_close_json(int fd, struct bpf_link_info *info)
                                           json_wtr);
                jsonw_uint_field(json_wtr, "target_obj_id", info->tracing.target_obj_id);
                jsonw_uint_field(json_wtr, "target_btf_id", info->tracing.target_btf_id);
+               jsonw_uint_field(json_wtr, "cookie", info->tracing.cookie);
                break;
        case BPF_LINK_TYPE_CGROUP:
                jsonw_lluint_field(json_wtr, "cgroup_id",
@@ -900,6 +901,8 @@ static int show_link_close_plain(int fd, struct bpf_link_info *info)
                        printf("\n\ttarget_obj_id %u  target_btf_id %u  ",
                               info->tracing.target_obj_id,
                               info->tracing.target_btf_id);
+               if (info->tracing.cookie)
+                       printf("\n\tcookie %llu  ", info->tracing.cookie);
                break;
        case BPF_LINK_TYPE_CGROUP:
                printf("\n\tcgroup_id %zu  ", (size_t)info->cgroup.cgroup_id);