From 56f668dfe00dcf086734f1c42ea999398fad6572 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Wed, 22 Mar 2017 10:00:33 -0700 Subject: bpf: Add array of maps support This patch adds a few helper funcs to enable map-in-map support (i.e. outer_map->inner_map). The first outer_map type BPF_MAP_TYPE_ARRAY_OF_MAPS is also added in this patch. The next patch will introduce a hash of maps type. Any bpf map type can be acted as an inner_map. The exception is BPF_MAP_TYPE_PROG_ARRAY because the extra level of indirection makes it harder to verify the owner_prog_type and owner_jited. Multi-level map-in-map is not supported (i.e. map->map is ok but not map->map->map). When adding an inner_map to an outer_map, it currently checks the map_type, key_size, value_size, map_flags, max_entries and ops. The verifier also uses those map's properties to do static analysis. map_flags is needed because we need to ensure BPF_PROG_TYPE_PERF_EVENT is using a preallocated hashtab for the inner_hash also. ops and max_entries are needed to generate inlined map-lookup instructions. For simplicity reason, a simple '==' test is used for both map_flags and max_entries. The equality of ops is implied by the equality of map_type. During outer_map creation time, an inner_map_fd is needed to create an outer_map. However, the inner_map_fd's life time does not depend on the outer_map. The inner_map_fd is merely used to initialize the inner_map_meta of the outer_map. Also, for the outer_map: * It allows element update and delete from syscall * It allows element lookup from bpf_prog The above is similar to the current fd_array pattern. Signed-off-by: Martin KaFai Lau Acked-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- include/uapi/linux/bpf.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/uapi/linux/bpf.h') diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 0539a0ceef38..1701ec1e7de3 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -96,6 +96,7 @@ 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, }; enum bpf_prog_type { @@ -152,6 +153,7 @@ 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 */ -- cgit v1.2.3-55-g7522