Commit 9343184c authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

Merge branch 'bpf: Show target_{obj,btf}_id for tracing link' 



Yafang Shao says:

====================
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.

For some other link types like perf_event and kprobe_multi, it is not
easy to find which functions are attached either. We may support
->fill_link_info for them in the future.

v1->v2:
- Skip showing them in the plain output for the old kernels. (Quentin)
- Coding improvement. (Andrii)
====================

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents effcf624 d7e45eb4

kernel/bpf/syscall.c

+9 −2
Original line number Diff line number Diff line
@@ -2968,10 +2968,17 @@ static void bpf_tracing_link_show_fdinfo(const struct bpf_link *link, 
{

	struct bpf_tracing_link *tr_link =

		container_of(link, struct bpf_tracing_link, link.link);

	u32 target_btf_id, target_obj_id;



	bpf_trampoline_unpack_key(tr_link->trampoline->key,

				  &target_obj_id, &target_btf_id);

	seq_printf(seq,

		   "attach_type:\t%d\n",

		   tr_link->attach_type);

		   "attach_type:\t%d\n"

		   "target_obj_id:\t%u\n"

		   "target_btf_id:\t%u\n",

		   tr_link->attach_type,

		   target_obj_id,

		   target_btf_id);

}



static int bpf_tracing_link_fill_link_info(const struct bpf_link *link,

tools/bpf/bpftool/link.c

+6 −0
Original line number Diff line number Diff line
@@ -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 +377,10 @@ 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);

		if (info->tracing.target_obj_id || info->tracing.target_btf_id)

			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);