libbpf: Add support for command BPF_ENABLE_STATS

bpf_enable_stats() is added to enable given stats.
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200430071506.1408910-3-songliubraving@fb.com

tools/lib/bpf/bpf.c

@@ -841,3 +841,13 @@ int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf, __u32 *buf_len,
 
 	return err;
 }
+
+int bpf_enable_stats(enum bpf_stats_type type)
+{
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.enable_stats.type = type;
+
+	return sys_bpf(BPF_ENABLE_STATS, &attr, sizeof(attr));
+}

tools/lib/bpf/bpf.h

@@ -231,6 +231,7 @@ LIBBPF_API int bpf_load_btf(void *btf, __u32 btf_size, char *log_buf,
 LIBBPF_API int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf,
 				 __u32 *buf_len, __u32 *prog_id, __u32 *fd_type,
 				 __u64 *probe_offset, __u64 *probe_addr);
+LIBBPF_API int bpf_enable_stats(enum bpf_stats_type type);
 
 #ifdef __cplusplus
 } /* extern "C" */

tools/lib/bpf/libbpf.map

@@ -257,6 +257,7 @@ LIBBPF_0.0.8 {
 
 LIBBPF_0.0.9 {
 	global:
+		bpf_enable_stats;
 		bpf_link_get_fd_by_id;
 		bpf_link_get_next_id;
 } LIBBPF_0.0.8;