Commit 1713e33b authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

Merge branch 'libbpf: deprecate legacy BPF map definitions' 



Andrii Nakryiko says:

====================

Officially deprecate legacy BPF map definitions in libbpf. They've been slated
for deprecation for a while in favor of more powerful BTF-defined map
definitions and this patch set adds warnings and a way to enforce this in
libbpf through LIBBPF_STRICT_MAP_DEFINITIONS strict mode flag.

Selftests are fixed up and updated, BPF documentation is updated, bpftool's
strict mode usage is adjusted to avoid breaking users unnecessarily.

v1->v2:
  - replace missed bpf_map_def case in Documentation/bpf/btf.rst (Alexei).
====================

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents 1058b6a7 96c85308

Documentation/bpf/btf.rst

+14 −18
Original line number Diff line number Diff line
@@ -565,18 +565,15 @@ A map can be created with ``btf_fd`` and specified key/value type id.:: 
In libbpf, the map can be defined with extra annotation like below:

::



    struct bpf_map_def SEC("maps") btf_map = {

        .type = BPF_MAP_TYPE_ARRAY,

        .key_size = sizeof(int),

        .value_size = sizeof(struct ipv_counts),

        .max_entries = 4,

    };

    BPF_ANNOTATE_KV_PAIR(btf_map, int, struct ipv_counts);

    struct {

        __uint(type, BPF_MAP_TYPE_ARRAY);

        __type(key, int);

        __type(value, struct ipv_counts);

        __uint(max_entries, 4);

    } btf_map SEC(".maps");



Here, the parameters for macro BPF_ANNOTATE_KV_PAIR are map name, key and

value types for the map. During ELF parsing, libbpf is able to extract

key/value type_id's and assign them to BPF_MAP_CREATE attributes

automatically.

During ELF parsing, libbpf is able to extract key/value type_id's and assign

them to BPF_MAP_CREATE attributes automatically.



.. _BPF_Prog_Load:
@@ -824,13 +821,12 @@ structure has bitfields. For example, for the following map,:: 
           ___A b1:4;

           enum A b2:4;

      };

      struct bpf_map_def SEC("maps") tmpmap = {

           .type = BPF_MAP_TYPE_ARRAY,

           .key_size = sizeof(__u32),

           .value_size = sizeof(struct tmp_t),

           .max_entries = 1,

      };

      BPF_ANNOTATE_KV_PAIR(tmpmap, int, struct tmp_t);

      struct {

           __uint(type, BPF_MAP_TYPE_ARRAY);

           __type(key, int);

           __type(value, struct tmp_t);

           __uint(max_entries, 1);

      } tmpmap SEC(".maps");



bpftool is able to pretty print like below:

::

tools/bpf/bpftool/main.c

+8 −1
Original line number Diff line number Diff line
@@ -478,7 +478,14 @@ int main(int argc, char **argv) 
	}



	if (!legacy_libbpf) {

		ret = libbpf_set_strict_mode(LIBBPF_STRICT_ALL);

		enum libbpf_strict_mode mode;



		/* Allow legacy map definitions for skeleton generation.

		 * It will still be rejected if users use LIBBPF_STRICT_ALL

		 * mode for loading generated skeleton.

		 */

		mode = (__LIBBPF_STRICT_LAST - 1) & ~LIBBPF_STRICT_MAP_DEFINITIONS;

		ret = libbpf_set_strict_mode(mode);

		if (ret)

			p_err("failed to enable libbpf strict mode: %d", ret);

	}

tools/lib/bpf/bpf_helpers.h

+1 −1
Original line number Diff line number Diff line
@@ -133,7 +133,7 @@ struct bpf_map_def { 
	unsigned int value_size;

	unsigned int max_entries;

	unsigned int map_flags;

};

} __attribute__((deprecated("use BTF-defined maps in .maps section")));



enum libbpf_pin_type {

	LIBBPF_PIN_NONE,

tools/lib/bpf/libbpf.c

+8 −0
Original line number Diff line number Diff line
@@ -1937,6 +1937,11 @@ static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict) 
	if (obj->efile.maps_shndx < 0)

		return 0;



	if (libbpf_mode & LIBBPF_STRICT_MAP_DEFINITIONS) {

		pr_warn("legacy map definitions in SEC(\"maps\") are not supported\n");

		return -EOPNOTSUPP;

	}



	if (!symbols)

		return -EINVAL;
@@ -1999,6 +2004,8 @@ static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict) 
			return -LIBBPF_ERRNO__FORMAT;

		}



		pr_warn("map '%s' (legacy): legacy map definitions are deprecated, use BTF-defined maps instead\n", map_name);



		if (ELF64_ST_BIND(sym->st_info) == STB_LOCAL) {

			pr_warn("map '%s' (legacy): static maps are not supported\n", map_name);

			return -ENOTSUP;
@@ -4190,6 +4197,7 @@ static int bpf_map_find_btf_info(struct bpf_object *obj, struct bpf_map *map) 
		return 0;



	if (!bpf_map__is_internal(map)) {

		pr_warn("Use of BPF_ANNOTATE_KV_PAIR is deprecated, use BTF-defined maps in .maps section instead\n");

		ret = btf__get_map_kv_tids(obj->btf, map->name, def->key_size,

					   def->value_size, &key_type_id,

					   &value_type_id);

tools/lib/bpf/libbpf_legacy.h

+5 −0
Original line number Diff line number Diff line
@@ -73,6 +73,11 @@ enum libbpf_strict_mode { 
	 * operation.

	 */

	LIBBPF_STRICT_AUTO_RLIMIT_MEMLOCK = 0x10,

	/*

	 * Error out on any SEC("maps") map definition, which are deprecated

	 * in favor of BTF-defined map definitions in SEC(".maps").

	 */

	LIBBPF_STRICT_MAP_DEFINITIONS = 0x20,



	__LIBBPF_STRICT_LAST,

};