From bcc6b1b7ebf857a9fe56202e2be3361131588c15 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Wed, 22 Mar 2017 10:00:34 -0700 Subject: 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 Acked-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- include/linux/bpf.h | 2 ++ include/uapi/linux/bpf.h | 1 + 2 files changed, 3 insertions(+) (limited to 'include') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 3f3cdf9b15e8..2ae39a3e9ead 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -277,6 +277,8 @@ int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value); int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file, void *key, void *value, u64 map_flags); void bpf_fd_array_map_clear(struct bpf_map *map); +int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file, + void *key, void *value, u64 map_flags); /* memcpy that is used with 8-byte aligned pointers, power-of-8 size and * forced to use 'long' read/writes to try to atomically copy long counters. diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 1701ec1e7de3..ce6f029ac368 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -97,6 +97,7 @@ enum bpf_map_type { 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 { -- cgit v1.2.3