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, 22 insertions, 0 deletions

diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
new file mode 100644
index 000000000000..74bb344035bb
--- /dev/null
+++ b/tools/lib/bpf/btf.h
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2018 Facebook */
+
+#ifndef __BPF_BTF_H
+#define __BPF_BTF_H
+
+#include <stdint.h>
+
+#define BTF_ELF_SEC ".BTF"
+
+struct btf;
+
+typedef int (*btf_print_fn_t)(const char *, ...)
+	__attribute__((format(printf, 1, 2)));
+
+void btf__free(struct btf *btf);
+struct btf *btf__new(uint8_t *data, uint32_t size, btf_print_fn_t err_log);
+int32_t btf__find_by_name(const struct btf *btf, const char *type_name);
+int64_t btf__resolve_size(const struct btf *btf, uint32_t type_id);
+int btf__fd(const struct btf *btf);
+
+#endif