bpf: Add tests for map-in-map

Test cases for array of maps and hash of maps.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/include/uapi/linux/bpf.h

@@ -96,6 +96,8 @@ enum bpf_map_type {
 	BPF_MAP_TYPE_LRU_HASH,
 	BPF_MAP_TYPE_LRU_PERCPU_HASH,
 	BPF_MAP_TYPE_LPM_TRIE,
+	BPF_MAP_TYPE_ARRAY_OF_MAPS,
+	BPF_MAP_TYPE_HASH_OF_MAPS,
 };
 
 enum bpf_prog_type {
@@ -152,6 +154,7 @@ union bpf_attr {
 		__u32	value_size;	/* size of value in bytes */
 		__u32	max_entries;	/* max number of entries in a map */
 		__u32	map_flags;	/* prealloc or not */
+		__u32	inner_map_fd;	/* fd pointing to the inner map */
 	};
 
 	struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */