BACKPORT: bpf: Use char in prog and map name

Instead of u8, use char for prog and map name.  It can avoid the
userspace tool getting compiler's signess warning.  The
bpf_prog_aux, bpf_map, bpf_attr, bpf_prog_info and
bpf_map_info are changed.

Change-Id: I599a8f1eccb0d63aa8d680b771fff1580c69cf75
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Cc: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/bpf.h

@@ -70,7 +70,7 @@ struct bpf_map {
 	atomic_t refcnt;
 	atomic_t usercnt;
 	struct work_struct work;
-	u8 name[BPF_OBJ_NAME_LEN];
+	char name[BPF_OBJ_NAME_LEN];
 };
 
 /* function argument constraints */
@@ -205,7 +205,7 @@ struct bpf_prog_aux {
 	void *security;
 #endif
 	u64 load_time; /* ns since boottime */
-	u8 name[BPF_OBJ_NAME_LEN];
+	char name[BPF_OBJ_NAME_LEN];
 	union {
 		struct work_struct work;
 		struct rcu_head	rcu;

include/uapi/linux/bpf.h

@@ -195,7 +195,7 @@ union bpf_attr {
 		__u32	numa_node;	/* numa node (effective only if
 					 * BPF_F_NUMA_NODE is set).
 					 */
-		__u8	map_name[BPF_OBJ_NAME_LEN];
+		char	map_name[BPF_OBJ_NAME_LEN];
 	};
 
 	struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */
@@ -218,7 +218,7 @@ union bpf_attr {
 		__aligned_u64	log_buf;	/* user supplied buffer */
 		__u32		kern_version;	/* checked when prog_type=kprobe */
 		__u32		prog_flags;
-		__u8		prog_name[BPF_OBJ_NAME_LEN];
+		char		prog_name[BPF_OBJ_NAME_LEN];
 	};
 
 	struct { /* anonymous struct used by BPF_OBJ_* commands */
@@ -887,7 +887,7 @@ struct bpf_prog_info {
 	__u32 created_by_uid;
 	__u32 nr_map_ids;
 	__aligned_u64 map_ids;
-	__u8  name[BPF_OBJ_NAME_LEN];
+	char name[BPF_OBJ_NAME_LEN];
 } __attribute__((aligned(8)));
 
 struct bpf_map_info {
@@ -897,7 +897,7 @@ struct bpf_map_info {
 	__u32 value_size;
 	__u32 max_entries;
 	__u32 map_flags;
-	__u8  name[BPF_OBJ_NAME_LEN];
+	char  name[BPF_OBJ_NAME_LEN];
 } __attribute__((aligned(8)));
 
 /* User bpf_sock_ops struct to access socket values and specify request ops