btf_dump_func
static int btf_dump_func(const struct btf *btf, char *func_sig,
func_sig_len = btf_dump_func(d->btf, prog_str, func_proto, NULL, 0,
pos = btf_dump_func(btf, func_sig, t, NULL, pos, size);
pos = btf_dump_func(btf, func_sig, proto_type, t, pos, size);