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authorMartin KaFai Lau <kafai@fb.com>2017-03-22 10:00:34 -0700
committerDavid S. Miller <davem@davemloft.net>2017-03-22 15:45:45 -0700
commitbcc6b1b7ebf857a9fe56202e2be3361131588c15 (patch)
treebc23c28ffe4866226ca8d768f67e74ddd9721076 /kernel/bpf/syscall.c
parent56f668dfe00dcf086734f1c42ea999398fad6572 (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/syscall.c')
-rw-r--r--kernel/bpf/syscall.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 6e24fdf1f373..c35ebfe6d84d 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -352,7 +352,8 @@ static int map_lookup_elem(union bpf_attr *attr)
err = bpf_percpu_array_copy(map, key, value);
} else if (map->map_type == BPF_MAP_TYPE_STACK_TRACE) {
err = bpf_stackmap_copy(map, key, value);
- } else if (map->map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS) {
+ } else if (map->map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
+ map->map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
err = -ENOTSUPP;
} else {
rcu_read_lock();
@@ -446,6 +447,11 @@ static int map_update_elem(union bpf_attr *attr)
err = bpf_fd_array_map_update_elem(map, f.file, key, value,
attr->flags);
rcu_read_unlock();
+ } else if (map->map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
+ rcu_read_lock();
+ err = bpf_fd_htab_map_update_elem(map, f.file, key, value,
+ attr->flags);
+ rcu_read_unlock();
} else {
rcu_read_lock();
err = map->ops->map_update_elem(map, key, value, attr->flags);