bpf: Introduce BPF_ANNOTATE_KV_PAIR

This patch introduces BPF_ANNOTATE_KV_PAIR to signal the
bpf loader about the btf key_type and value_type of a bpf map.
Please refer to the changes in test_btf_haskv.c for its usage.
Both iproute2 and libbpf loader will then have the same
convention to find out the map's btf_key_type_id and
btf_value_type_id from a map's name.

Fixes: 8a138aed4a80 ("bpf: btf: Add BTF support to libbpf")
Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index ed3a84370ccc..e2a09a155f84 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -9,6 +9,7 @@
 #define BTF_ELF_SEC ".BTF"
 
 struct btf;
+struct btf_type;
 
 typedef int (*btf_print_fn_t)(const char *, ...)
 	__attribute__((format(printf, 1, 2)));
@@ -16,6 +17,7 @@ typedef int (*btf_print_fn_t)(const char *, ...)
 void btf__free(struct btf *btf);
 struct btf *btf__new(__u8 *data, __u32 size, btf_print_fn_t err_log);
 __s32 btf__find_by_name(const struct btf *btf, const char *type_name);
+const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 id);
 __s64 btf__resolve_size(const struct btf *btf, __u32 type_id);
 int btf__fd(const struct btf *btf);