Introduce BPF_F_ALL_CPUS flag support for percpu_cgroup_storage maps to
allow updating values for all CPUs with a single value.
Introduce BPF_F_CPU flag support for percpu_cgroup_storage maps to allow
updating value for specified CPU.
This enhancement enables:
* Efficient update values across all CPUs with a single value when
BPF_F_ALL_CPUS is set for update_elem API.
* Targeted update or lookup for a specified CPU when BPF_F_CPU is set.
The BPF_F_CPU flag is passed via map_flags of lookup_elem and update_elem
APIs along with embedded cpu field.
Signed-off-by: Leon Hwang <leon.hwang@xxxxxxxxx>
---
include/linux/bpf-cgroup.h | 5 ++--
include/linux/bpf.h | 5 ++--
kernel/bpf/local_storage.c | 47 +++++++++++++++++++++++++++++---------
kernel/bpf/syscall.c | 12 ++++------
4 files changed, 46 insertions(+), 23 deletions(-)
diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index aedf573bdb426..1cb28660aa866 100644
--- a/include/linux/bpf-cgroup.h
+++ b/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,
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index dc715eef9cbf4..2684ba32bba0a 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -3733,12 +3733,13 @@ static inline int bpf_map_check_cpu_flags(u64 flags, bool check_all_cpus)
return 0;
}
-static inline bool bpf_map_support_cpu_flags(enum bpf_map_type map_type)
+static inline bool bpf_map_is_percpu(enum bpf_map_type map_type)
{
switch (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;
@@ -3756,7 +3757,7 @@ static inline int bpf_map_check_flags(struct bpf_map *map, u64 flags, bool check
if (!(flags & BPF_F_CPU) && flags >> 32)
return -EINVAL;
- if ((flags & (BPF_F_CPU | BPF_F_ALL_CPUS)) && !bpf_map_support_cpu_flags(map->map_type))
+ if ((flags & (BPF_F_CPU | BPF_F_ALL_CPUS)) && !bpf_map_is_percpu(map->map_type))
return -EINVAL;
return 0;
diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
index c93a756e035c0..ee60b8cee4e90 100644
--- a/kernel/bpf/local_storage.c
+++ b/kernel/bpf/local_storage.c
@@ -180,18 +180,22 @@ 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;
+ int cpu, off = 0, err;
u32 size;
+ 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
@@ -199,13 +203,19 @@ int bpf_percpu_cgroup_storage_copy(struct bpf_map *_map, void *key,
* will not leak any kernel data
*/
size = round_up(_map->value_size, 8);
+ if (map_flags & BPF_F_CPU) {
+ cpu = map_flags >> 32;
+ bpf_long_memcpy(value, per_cpu_ptr(storage->percpu_buf, cpu), size);
+ goto unlock;
+ }
for_each_possible_cpu(cpu) {
bpf_long_memcpy(value + off,
per_cpu_ptr(storage->percpu_buf, cpu), size);
off += size;
}
+unlock:
rcu_read_unlock();
- return 0;
+ return err;
}
int bpf_percpu_cgroup_storage_update(struct bpf_map *_map, void *key,
@@ -213,17 +223,21 @@ int bpf_percpu_cgroup_storage_update(struct bpf_map *_map, void *key,
{
struct bpf_cgroup_storage_map *map = map_to_storage(_map);
struct bpf_cgroup_storage *storage;
- int cpu, off = 0;
+ int cpu, off = 0, err;
u32 size;
- 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 +247,24 @@ 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);
+ if (map_flags & BPF_F_CPU) {
+ cpu = map_flags >> 32;
+ bpf_long_memcpy(per_cpu_ptr(storage->percpu_buf, cpu), value, size);
+ goto unlock;
+ }
for_each_possible_cpu(cpu) {
bpf_long_memcpy(per_cpu_ptr(storage->percpu_buf, cpu),
value + off, size);
- off += size;
+ /* same user-provided value is used if
+ * BPF_F_ALL_CPUS is specified, otherwise value is
+ * an array of per-cpu values.
+ */
+ if (!(map_flags & BPF_F_ALL_CPUS))
+ off += size;
}
+unlock:
rcu_read_unlock();
- return 0;
+ return err;
}
static int cgroup_storage_get_next_key(struct bpf_map *_map, void *key,
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 430f013f38f06..3fc52cd0c12de 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -133,13 +133,9 @@ bool bpf_map_write_active(const struct bpf_map *map)
static u32 bpf_map_value_size(const struct bpf_map *map, u64 flags)
{
- if (bpf_map_support_cpu_flags(map->map_type) && (flags & (BPF_F_CPU | BPF_F_ALL_CPUS)))
- return round_up(map->value_size, 8);
- else if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
- map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH ||
- map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY ||
- map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE)
- return round_up(map->value_size, 8) * num_possible_cpus();
+ if (bpf_map_is_percpu(map->map_type))
+ return flags & (BPF_F_CPU | BPF_F_ALL_CPUS) ? round_up(map->value_size, 8) :
+ round_up(map->value_size, 8) * num_possible_cpus();
else if (IS_FD_MAP(map))
return sizeof(u32);
else
@@ -318,7 +314,7 @@ 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)) {
--
2.50.1
