Introduce support for the BPF_F_ALL_CPUS flag in percpu_array maps to
allow updating values for all CPUs with a single value.
Introduce support for the BPF_F_CPU flag in percpu_array 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 and update_batch APIs.
* 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.
* elem_flags of lookup_batch and update_batch APIs along with embedded
cpu field.
Signed-off-by: Leon Hwang <leon.hwang@xxxxxxxxx>
---
include/linux/bpf.h | 3 +-
include/uapi/linux/bpf.h | 2 ++
kernel/bpf/arraymap.c | 56 ++++++++++++++++++++++++++--------
kernel/bpf/syscall.c | 27 ++++++++++------
tools/include/uapi/linux/bpf.h | 2 ++
5 files changed, 67 insertions(+), 23 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 8f6e87f0f3a89..b2191b1e455a6 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2697,7 +2697,8 @@ int map_set_for_each_callback_args(struct bpf_verifier_env *env,
struct bpf_func_state *callee);
int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value);
-int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value);
+int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value,
+ u64 flags);
int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value,
u64 flags);
int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 233de8677382e..be1fdc5042744 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1372,6 +1372,8 @@ enum {
BPF_NOEXIST = 1, /* create new element if it didn't exist */
BPF_EXIST = 2, /* update existing element */
BPF_F_LOCK = 4, /* spin_lock-ed map_lookup/map_update */
+ BPF_F_CPU = 8, /* cpu flag for percpu maps, upper 32-bit of flags is a cpu number */
+ BPF_F_ALL_CPUS = 16, /* update value across all CPUs for percpu maps */
};
/* flags for BPF_MAP_CREATE command */
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 3d080916faf97..1efa730105e24 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -295,17 +295,24 @@ static void *percpu_array_map_lookup_percpu_elem(struct bpf_map *map, void *key,
return per_cpu_ptr(array->pptrs[index & array->index_mask], cpu);
}
-int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value)
+int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value, u64 flags)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
u32 index = *(u32 *)key;
void __percpu *pptr;
- int cpu, off = 0;
- u32 size;
+ u32 size, cpu;
+ int off = 0;
if (unlikely(index >= array->map.max_entries))
return -ENOENT;
+ if (unlikely((u32)flags & ~BPF_F_CPU))
+ return -EINVAL;
+
+ cpu = flags >> 32;
+ if (unlikely((flags & BPF_F_CPU) && cpu >= num_possible_cpus()))
+ return -ERANGE;
+
/* 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
@@ -313,10 +320,15 @@ int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value)
size = array->elem_size;
rcu_read_lock();
pptr = array->pptrs[index & array->index_mask];
- for_each_possible_cpu(cpu) {
- copy_map_value_long(map, value + off, per_cpu_ptr(pptr, cpu));
- check_and_init_map_value(map, value + off);
- off += size;
+ if (flags & BPF_F_CPU) {
+ copy_map_value_long(map, value, per_cpu_ptr(pptr, cpu));
+ check_and_init_map_value(map, value);
+ } else {
+ for_each_possible_cpu(cpu) {
+ copy_map_value_long(map, value + off, per_cpu_ptr(pptr, cpu));
+ check_and_init_map_value(map, value + off);
+ off += size;
+ }
}
rcu_read_unlock();
return 0;
@@ -385,14 +397,22 @@ int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
u64 map_flags)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
+ const u64 cpu_flags = BPF_F_CPU | BPF_F_ALL_CPUS;
u32 index = *(u32 *)key;
void __percpu *pptr;
- int cpu, off = 0;
- u32 size;
+ u32 size, cpu;
+ int off = 0;
- if (unlikely(map_flags > BPF_EXIST))
+ if (unlikely((u32)map_flags > BPF_F_ALL_CPUS))
/* unknown flags */
return -EINVAL;
+ if (unlikely((map_flags & cpu_flags) == cpu_flags))
+ return -EINVAL;
+
+ cpu = map_flags >> 32;
+ if (unlikely((map_flags & BPF_F_CPU) && cpu >= num_possible_cpus()))
+ /* invalid cpu */
+ return -ERANGE;
if (unlikely(index >= array->map.max_entries))
/* all elements were pre-allocated, cannot insert a new one */
@@ -411,10 +431,20 @@ int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
size = array->elem_size;
rcu_read_lock();
pptr = array->pptrs[index & array->index_mask];
- for_each_possible_cpu(cpu) {
- copy_map_value_long(map, per_cpu_ptr(pptr, cpu), value + off);
+ if (map_flags & BPF_F_CPU) {
+ copy_map_value_long(map, per_cpu_ptr(pptr, cpu), value);
bpf_obj_free_fields(array->map.record, per_cpu_ptr(pptr, cpu));
- off += size;
+ } else {
+ for_each_possible_cpu(cpu) {
+ copy_map_value_long(map, per_cpu_ptr(pptr, cpu), value + off);
+ /* 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;
+ bpf_obj_free_fields(array->map.record, per_cpu_ptr(pptr, cpu));
+ }
}
rcu_read_unlock();
return 0;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 19f7f5de5e7dc..6251ac9bc7e42 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -131,9 +131,11 @@ bool bpf_map_write_active(const struct bpf_map *map)
return atomic64_read(&map->writecnt) != 0;
}
-static u32 bpf_map_value_size(const struct bpf_map *map)
+static u32 bpf_map_value_size(const struct bpf_map *map, u64 flags)
{
- if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
+ if (map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY && (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)
@@ -314,7 +316,7 @@ static int bpf_map_copy_value(struct bpf_map *map, void *key, void *value,
map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH) {
err = bpf_percpu_hash_copy(map, key, value);
} else if (map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY) {
- err = bpf_percpu_array_copy(map, key, value);
+ 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);
} else if (map->map_type == BPF_MAP_TYPE_STACK_TRACE) {
@@ -1656,12 +1658,19 @@ static void *___bpf_copy_key(bpfptr_t ukey, u64 key_size)
static int check_map_flags(struct bpf_map *map, u64 flags, bool check_flag)
{
- if (check_flag && (flags & ~BPF_F_LOCK))
+ if (check_flag && ((u32)flags & ~(BPF_F_LOCK | BPF_F_CPU | BPF_F_ALL_CPUS)))
return -EINVAL;
if ((flags & BPF_F_LOCK) && !btf_record_has_field(map->record, BPF_SPIN_LOCK))
return -EINVAL;
+ if (!(flags & BPF_F_CPU) && flags >> 32)
+ return -EINVAL;
+
+ if ((flags & (BPF_F_CPU | BPF_F_ALL_CPUS)) &&
+ map->map_type != BPF_MAP_TYPE_PERCPU_ARRAY)
+ return -EINVAL;
+
return 0;
}
@@ -1695,7 +1704,7 @@ static int map_lookup_elem(union bpf_attr *attr)
if (IS_ERR(key))
return PTR_ERR(key);
- value_size = bpf_map_value_size(map);
+ value_size = bpf_map_value_size(map, attr->flags);
err = -ENOMEM;
value = kvmalloc(value_size, GFP_USER | __GFP_NOWARN);
@@ -1762,7 +1771,7 @@ static int map_update_elem(union bpf_attr *attr, bpfptr_t uattr)
goto err_put;
}
- value_size = bpf_map_value_size(map);
+ value_size = bpf_map_value_size(map, attr->flags);
value = kvmemdup_bpfptr(uvalue, value_size);
if (IS_ERR(value)) {
err = PTR_ERR(value);
@@ -1962,7 +1971,7 @@ int generic_map_update_batch(struct bpf_map *map, struct file *map_file,
if (err)
return err;
- value_size = bpf_map_value_size(map);
+ value_size = bpf_map_value_size(map, attr->batch.elem_flags);
max_count = attr->batch.count;
if (!max_count)
@@ -2021,7 +2030,7 @@ int generic_map_lookup_batch(struct bpf_map *map,
if (err)
return err;
- value_size = bpf_map_value_size(map);
+ value_size = bpf_map_value_size(map, attr->batch.elem_flags);
max_count = attr->batch.count;
if (!max_count)
@@ -2143,7 +2152,7 @@ static int map_lookup_and_delete_elem(union bpf_attr *attr)
goto err_put;
}
- value_size = bpf_map_value_size(map);
+ value_size = bpf_map_value_size(map, 0);
err = -ENOMEM;
value = kvmalloc(value_size, GFP_USER | __GFP_NOWARN);
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 233de8677382e..be1fdc5042744 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1372,6 +1372,8 @@ enum {
BPF_NOEXIST = 1, /* create new element if it didn't exist */
BPF_EXIST = 2, /* update existing element */
BPF_F_LOCK = 4, /* spin_lock-ed map_lookup/map_update */
+ BPF_F_CPU = 8, /* cpu flag for percpu maps, upper 32-bit of flags is a cpu number */
+ BPF_F_ALL_CPUS = 16, /* update value across all CPUs for percpu maps */
};
/* flags for BPF_MAP_CREATE command */
--
2.50.1
