Commit e60495ea authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov
Browse files

bpftool: Implement link_query for bpf iterators 



The link query for bpf iterators is implemented.
Besides being shown to the user what bpf iterator
the link represents, the target_name is also used
to filter out what additional information should be
printed out, e.g., whether map_id should be shown or not.
The following is an example of bpf_iter link dump,
plain output or pretty output.

  $ bpftool link show
  11: iter  prog 59  target_name task
          pids test_progs(1749)
  34: iter  prog 173  target_name bpf_map_elem  map_id 127
          pids test_progs_1(1753)
  $ bpftool -p link show
  [{
          "id": 11,
          "type": "iter",
          "prog_id": 59,
          "target_name": "task",
          "pids": [{
                  "pid": 1749,
                  "comm": "test_progs"
              }
          ]
      },{
          "id": 34,
          "type": "iter",
          "prog_id": 173,
          "target_name": "bpf_map_elem",
          "map_id": 127,
          "pids": [{
                  "pid": 1753,
                  "comm": "test_progs_1"
              }
          ]
      }
  ]

Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200821184420.574430-1-yhs@fb.com
parent b76f2226

tools/bpf/bpftool/link.c

+41 −3
Original line number Diff line number Diff line
@@ -77,6 +77,22 @@ static void show_link_attach_type_json(__u32 attach_type, json_writer_t *wtr) 
		jsonw_uint_field(wtr, "attach_type", attach_type);

}



static bool is_iter_map_target(const char *target_name)

{

	return strcmp(target_name, "bpf_map_elem") == 0 ||

	       strcmp(target_name, "bpf_sk_storage_map") == 0;

}



static void show_iter_json(struct bpf_link_info *info, json_writer_t *wtr)

{

	const char *target_name = u64_to_ptr(info->iter.target_name);



	jsonw_string_field(wtr, "target_name", target_name);



	if (is_iter_map_target(target_name))

		jsonw_uint_field(wtr, "map_id", info->iter.map.map_id);

}



static int get_prog_info(int prog_id, struct bpf_prog_info *info)

{

	__u32 len = sizeof(*info);
@@ -128,6 +144,9 @@ static int show_link_close_json(int fd, struct bpf_link_info *info) 
				   info->cgroup.cgroup_id);

		show_link_attach_type_json(info->cgroup.attach_type, json_wtr);

		break;

	case BPF_LINK_TYPE_ITER:

		show_iter_json(info, json_wtr);

		break;

	case BPF_LINK_TYPE_NETNS:

		jsonw_uint_field(json_wtr, "netns_ino",

				 info->netns.netns_ino);
@@ -175,6 +194,16 @@ static void show_link_attach_type_plain(__u32 attach_type) 
		printf("attach_type %u  ", attach_type);

}



static void show_iter_plain(struct bpf_link_info *info)

{

	const char *target_name = u64_to_ptr(info->iter.target_name);



	printf("target_name %s  ", target_name);



	if (is_iter_map_target(target_name))

		printf("map_id %u  ", info->iter.map.map_id);

}



static int show_link_close_plain(int fd, struct bpf_link_info *info)

{

	struct bpf_prog_info prog_info;
@@ -204,6 +233,9 @@ static int show_link_close_plain(int fd, struct bpf_link_info *info) 
		printf("\n\tcgroup_id %zu  ", (size_t)info->cgroup.cgroup_id);

		show_link_attach_type_plain(info->cgroup.attach_type);

		break;

	case BPF_LINK_TYPE_ITER:

		show_iter_plain(info);

		break;

	case BPF_LINK_TYPE_NETNS:

		printf("\n\tnetns_ino %u  ", info->netns.netns_ino);

		show_link_attach_type_plain(info->netns.attach_type);
@@ -231,7 +263,7 @@ static int do_show_link(int fd) 
{

	struct bpf_link_info info;

	__u32 len = sizeof(info);

	char raw_tp_name[256];

	char buf[256];

	int err;



	memset(&info, 0, sizeof(info));
@@ -245,8 +277,14 @@ again: 
	}

	if (info.type == BPF_LINK_TYPE_RAW_TRACEPOINT &&

	    !info.raw_tracepoint.tp_name) {

		info.raw_tracepoint.tp_name = (unsigned long)&raw_tp_name;

		info.raw_tracepoint.tp_name_len = sizeof(raw_tp_name);

		info.raw_tracepoint.tp_name = (unsigned long)&buf;

		info.raw_tracepoint.tp_name_len = sizeof(buf);

		goto again;

	}

	if (info.type == BPF_LINK_TYPE_ITER &&

	    !info.iter.target_name) {

		info.iter.target_name = (unsigned long)&buf;

		info.iter.target_name_len = sizeof(buf);

		goto again;

	}

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