1. 29 Jun, 2017 1 commit
  2. 22 Mar, 2017 1 commit
    • Martin KaFai Lau's avatar
      bpf: Add array of maps support · 56f668df
      Martin KaFai Lau authored
      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: 's avatarMartin KaFai Lau <kafai@fb.com>
      Acked-by: 's avatarAlexei Starovoitov <ast@kernel.org>
      Acked-by: 's avatarDaniel Borkmann <daniel@iogearbox.net>
      Signed-off-by: 's avatarDavid S. Miller <davem@davemloft.net>
      56f668df