The target_btf_id can help us understand which kernel function is
linked by a tracing prog. The target_btf_id and target_obj_id have
already been exposed to userspace, so we just need to show them.
The result as follows,
$ tools/bpf/bpftool/bpftool link show
2: tracing prog 13
prog_type tracing attach_type trace_fentry
target_obj_id 1 target_btf_id 13964
pids trace(10673)
$ tools/bpf/bpftool/bpftool link show -j
[{"id":2,"type":"tracing","prog_id":13,"prog_type":"tracing","attach_type":"trace_fentry","target_obj_id":1,"target_btf_id":13964,"pids":[{"pid":10673,"comm":"trace"}]}]
Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
Acked-by: Song Liu <song@xxxxxxxxxx>
---
tools/bpf/bpftool/link.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/tools/bpf/bpftool/link.c b/tools/bpf/bpftool/link.c
index 243b74e..cfe896f 100644
--- a/tools/bpf/bpftool/link.c
+++ b/tools/bpf/bpftool/link.c
@@ -195,6 +195,8 @@ static int show_link_close_json(int fd, struct bpf_link_info *info)
show_link_attach_type_json(info->tracing.attach_type,
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);
break;
case BPF_LINK_TYPE_CGROUP:
jsonw_lluint_field(json_wtr, "cgroup_id",
@@ -375,6 +377,8 @@ static int show_link_close_plain(int fd, struct bpf_link_info *info)
printf("\n\tprog_type %u ", prog_info.type);
show_link_attach_type_plain(info->tracing.attach_type);
+ printf("\n\ttarget_obj_id %u target_btf_id %u ",
+ info->tracing.target_obj_id, info->tracing.target_btf_id);
break;
case BPF_LINK_TYPE_CGROUP:
printf("\n\tcgroup_id %zu ", (size_t)info->cgroup.cgroup_id);
--
1.8.3.1
