bpf: Introduce BPF_F_CPU and BPF_F_ALL_CPUS flags for percpu_cgroup_storage maps

Introduce BPF_F_ALL_CPUS flag support for percpu_cgroup_storage maps to
allow updating values for all CPUs with a single value for update_elem
API.

Introduce BPF_F_CPU flag support for percpu_cgroup_storage maps to
allow:

* update value for specified CPU for update_elem API.
* lookup value for specified CPU for lookup_elem API.

The BPF_F_CPU flag is passed via map_flags along with embedded cpu info.

Signed-off-by: Leon Hwang <[email protected]>

Author: Asphaltt

include/linux/bpf-cgroup.h

@@ -172,7 +172,8 @@ void bpf_cgroup_storage_link(struct bpf_cgroup_storage *storage,
 void bpf_cgroup_storage_unlink(struct bpf_cgroup_storage *storage);
 int bpf_cgroup_storage_assign(struct bpf_prog_aux *aux, struct bpf_map *map);
 
-int bpf_percpu_cgroup_storage_copy(struct bpf_map *map, void *key, void *value);
+int bpf_percpu_cgroup_storage_copy(struct bpf_map *map, void *key, void *value,
+				   u64 flags);
 int bpf_percpu_cgroup_storage_update(struct bpf_map *map, void *key,
 				     void *value, u64 flags);
 
@@ -467,7 +468,7 @@ static inline struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(
 static inline void bpf_cgroup_storage_free(
 	struct bpf_cgroup_storage *storage) {}
 static inline int bpf_percpu_cgroup_storage_copy(struct bpf_map *map, void *key,
-						 void *value) {
+						 void *value, u64 flags) {
 	return 0;
 }
 static inline int bpf_percpu_cgroup_storage_update(struct bpf_map *map,

include/linux/bpf.h

@@ -3765,6 +3765,7 @@ static inline bool bpf_map_supports_cpu_flags(enum bpf_map_type map_type)
 	case BPF_MAP_TYPE_PERCPU_ARRAY:
 	case BPF_MAP_TYPE_PERCPU_HASH:
 	case BPF_MAP_TYPE_LRU_PERCPU_HASH:
+	case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
 		return true;
 	default:
 		return false;

kernel/bpf/local_storage.c

@@ -180,50 +180,55 @@ static long cgroup_storage_update_elem(struct bpf_map *map, void *key,
 }
 
 int bpf_percpu_cgroup_storage_copy(struct bpf_map *_map, void *key,
-				   void *value)
+				   void *value, u64 map_flags)
 {
 	struct bpf_cgroup_storage_map *map = map_to_storage(_map);
 	struct bpf_cgroup_storage *storage;
-	int cpu, off = 0;
 	u32 size;
+	int err;
+
+	err = bpf_map_check_cpu_flags(map_flags, false);
+	if (err)
+		return err;
 
 	rcu_read_lock();
 	storage = cgroup_storage_lookup(map, key, false);
 	if (!storage) {
-		rcu_read_unlock();
-		return -ENOENT;
+		err = -ENOENT;
+		goto unlock;
 	}
 
 	/* per_cpu areas are zero-filled and bpf programs can only
 	 * access 'value_size' of them, so copying rounded areas
 	 * will not leak any kernel data
 	 */
 	size = round_up(_map->value_size, 8);
-	for_each_possible_cpu(cpu) {
-		bpf_long_memcpy(value + off,
-				per_cpu_ptr(storage->percpu_buf, cpu), size);
-		off += size;
-	}
+	bpf_percpu_copy_to_user(_map, storage->percpu_buf, value, size, map_flags);
+unlock:
 	rcu_read_unlock();
-	return 0;
+	return err;
 }
 
 int bpf_percpu_cgroup_storage_update(struct bpf_map *_map, void *key,
 				     void *value, u64 map_flags)
 {
 	struct bpf_cgroup_storage_map *map = map_to_storage(_map);
 	struct bpf_cgroup_storage *storage;
-	int cpu, off = 0;
 	u32 size;
+	int err;
 
-	if (map_flags != BPF_ANY && map_flags != BPF_EXIST)
+	if ((u32)map_flags & ~(BPF_ANY | BPF_EXIST | BPF_F_CPU | BPF_F_ALL_CPUS))
 		return -EINVAL;
 
+	err = bpf_map_check_cpu_flags(map_flags, true);
+	if (err)
+		return err;
+
 	rcu_read_lock();
 	storage = cgroup_storage_lookup(map, key, false);
 	if (!storage) {
-		rcu_read_unlock();
-		return -ENOENT;
+		err = -ENOENT;
+		goto unlock;
 	}
 
 	/* the user space will provide round_up(value_size, 8) bytes that
@@ -233,13 +238,10 @@ int bpf_percpu_cgroup_storage_update(struct bpf_map *_map, void *key,
 	 * so no kernel data leaks possible
 	 */
 	size = round_up(_map->value_size, 8);
-	for_each_possible_cpu(cpu) {
-		bpf_long_memcpy(per_cpu_ptr(storage->percpu_buf, cpu),
-				value + off, size);
-		off += size;
-	}
+	bpf_percpu_copy_from_user(_map, storage->percpu_buf, value, size, map_flags);
+unlock:
 	rcu_read_unlock();
-	return 0;
+	return err;
 }
 
 static int cgroup_storage_get_next_key(struct bpf_map *_map, void *key,

kernel/bpf/syscall.c

@@ -318,7 +318,7 @@ static int bpf_map_copy_value(struct bpf_map *map, void *key, void *value,
 	} else if (map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY) {
 		err = bpf_percpu_array_copy(map, key, value, flags);
 	} else if (map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE) {
-		err = bpf_percpu_cgroup_storage_copy(map, key, value);
+		err = bpf_percpu_cgroup_storage_copy(map, key, value, flags);
 	} else if (map->map_type == BPF_MAP_TYPE_STACK_TRACE) {
 		err = bpf_stackmap_copy(map, key, value);
 	} else if (IS_FD_ARRAY(map) || IS_FD_PROG_ARRAY(map)) {