diff options
| author | Martin KaFai Lau <kafai@fb.com> | 2017-03-22 10:00:34 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-03-22 15:45:45 -0700 |
| commit | bcc6b1b7ebf857a9fe56202e2be3361131588c15 (patch) | |
| tree | bc23c28ffe4866226ca8d768f67e74ddd9721076 /kernel/bpf/verifier.c | |
| parent | 56f668dfe00dcf086734f1c42ea999398fad6572 (diff) | |
bpf: Add hash of maps support
This patch adds hash of maps support (hashmap->bpf_map).
BPF_MAP_TYPE_HASH_OF_MAPS is added.
A map-in-map contains a pointer to another map and lets call
this pointer 'inner_map_ptr'.
Notes on deleting inner_map_ptr from a hash map:
1. For BPF_F_NO_PREALLOC map-in-map, when deleting
an inner_map_ptr, the htab_elem itself will go through
a rcu grace period and the inner_map_ptr resides
in the htab_elem.
2. For pre-allocated htab_elem (!BPF_F_NO_PREALLOC),
when deleting an inner_map_ptr, the htab_elem may
get reused immediately. This situation is similar
to the existing prealloc-ated use cases.
However, the bpf_map_fd_put_ptr() calls bpf_map_put() which calls
inner_map->ops->map_free(inner_map) which will go
through a rcu grace period (i.e. all bpf_map's map_free
currently goes through a rcu grace period). Hence,
the inner_map_ptr is still safe for the rcu reader side.
This patch also includes BPF_MAP_TYPE_HASH_OF_MAPS to the
check_map_prealloc() in the verifier. preallocation is a
must for BPF_PROG_TYPE_PERF_EVENT. Hence, even we don't expect
heavy updates to map-in-map, enforcing BPF_F_NO_PREALLOC for map-in-map
is impossible without disallowing BPF_PROG_TYPE_PERF_EVENT from using
map-in-map first.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf/verifier.c')
| -rw-r--r-- | kernel/bpf/verifier.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 3b8f528c5473..09923cc5c7c7 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1200,6 +1200,7 @@ static int check_map_func_compatibility(struct bpf_map *map, int func_id) goto error; break; case BPF_MAP_TYPE_ARRAY_OF_MAPS: + case BPF_MAP_TYPE_HASH_OF_MAPS: if (func_id != BPF_FUNC_map_lookup_elem) goto error; default: @@ -3044,7 +3045,8 @@ process_bpf_exit: static int check_map_prealloc(struct bpf_map *map) { return (map->map_type != BPF_MAP_TYPE_HASH && - map->map_type != BPF_MAP_TYPE_PERCPU_HASH) || + map->map_type != BPF_MAP_TYPE_PERCPU_HASH && + map->map_type != BPF_MAP_TYPE_HASH_OF_MAPS) || !(map->map_flags & BPF_F_NO_PREALLOC); } |