bpf: btf: Add BTF support to libbpf

If the ".BTF" elf section exists, libbpf will try to create
a btf_fd (through BPF_BTF_LOAD).  If that fails, it will still
continue loading the bpf prog/map without the BTF.

If the bpf_object has a BTF loaded, it will create a map with the btf_fd.
libbpf will try to figure out the btf_key_id and btf_value_id of a map by
finding the BTF type with name "<map_name>_key" and "<map_name>_value".
If they cannot be found, it will continue without using the BTF.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 8b242486b464..d6ac4fa6f472 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -78,6 +78,7 @@ int bpf_object__load(struct bpf_object *obj);
 int bpf_object__unload(struct bpf_object *obj);
 const char *bpf_object__name(struct bpf_object *obj);
 unsigned int bpf_object__kversion(struct bpf_object *obj);
+int bpf_object__btf_fd(const struct bpf_object *obj);
 
 struct bpf_object *bpf_object__next(struct bpf_object *prev);
 #define bpf_object__for_each_safe(pos, tmp)                     \
@@ -241,6 +242,8 @@ bpf_map__next(struct bpf_map *map, struct bpf_object *obj);
 int bpf_map__fd(struct bpf_map *map);
 const struct bpf_map_def *bpf_map__def(struct bpf_map *map);
 const char *bpf_map__name(struct bpf_map *map);
+uint32_t bpf_map__btf_key_id(const struct bpf_map *map);
+uint32_t bpf_map__btf_value_id(const struct bpf_map *map);
 
 typedef void (*bpf_map_clear_priv_t)(struct bpf_map *, void *);
 int bpf_map__set_priv(struct bpf_map *map, void *priv,