bpf: Allows per-cpu maps and map-in-map in sleepable programs

mainline inclusion
from mainline-5.12-rc1
commit 638e4b82
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=638e4b825d523bed7a55e776c153049fb7716466

-------------------------------------------------

Since sleepable programs are now executing under migrate_disable
the per-cpu maps are safe to use.
The map-in-map were ok to use in sleepable from the time sleepable
progs were introduced.

Note that non-preallocated maps are still not safe, since there is
no rcu_read_lock yet in sleepable programs and dynamically allocated
map elements are relying on rcu protection. The sleepable programs
have rcu_read_lock_trace instead. That limitation will be addresses
in the future.
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAndrii Nakryiko <andrii@kernel.org>
Acked-by: NKP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/bpf/20210210033634.62081-9-alexei.starovoitov@gmail.com
(cherry picked from commit 638e4b82)
Signed-off-by: NWang Yufen <wangyufen@huawei.com>

kernel/bpf/hashtab.c

@@ -1122,7 +1122,7 @@ static int __htab_percpu_map_update_elem(struct bpf_map *map, void *key,
 		/* unknown flags */
 		return -EINVAL;
 
-	WARN_ON_ONCE(!rcu_read_lock_held());
+	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held());
 
 	key_size = map->key_size;
 
@@ -1174,7 +1174,7 @@ static int __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
 		/* unknown flags */
 		return -EINVAL;
 
-	WARN_ON_ONCE(!rcu_read_lock_held());
+	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held());
 
 	key_size = map->key_size;
 

kernel/bpf/verifier.c

@@ -10462,9 +10462,14 @@ static int check_map_prog_compatibility(struct bpf_verifier_env *env,
 		case BPF_MAP_TYPE_HASH:
 		case BPF_MAP_TYPE_LRU_HASH:
 		case BPF_MAP_TYPE_ARRAY:
+		case BPF_MAP_TYPE_PERCPU_HASH:
+		case BPF_MAP_TYPE_PERCPU_ARRAY:
+		case BPF_MAP_TYPE_LRU_PERCPU_HASH:
+		case BPF_MAP_TYPE_ARRAY_OF_MAPS:
+		case BPF_MAP_TYPE_HASH_OF_MAPS:
 			if (!is_preallocated_map(map)) {
 				verbose(env,
-					"Sleepable programs can only use preallocated hash maps\n");
+					"Sleepable programs can only use preallocated maps\n");
 				return -EINVAL;
 			}
 			break;