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Message-ID: <20251117162033.6296-4-leon.hwang@linux.dev>
Date: Tue, 18 Nov 2025 00:20:28 +0800
From: Leon Hwang <leon.hwang@...ux.dev>
To: bpf@...r.kernel.org
Cc: ast@...nel.org,
andrii@...nel.org,
daniel@...earbox.net,
jolsa@...nel.org,
yonghong.song@...ux.dev,
song@...nel.org,
eddyz87@...il.com,
dxu@...uu.xyz,
deso@...teo.net,
martin.lau@...ux.dev,
john.fastabend@...il.com,
kpsingh@...nel.org,
sdf@...ichev.me,
haoluo@...gle.com,
shuah@...nel.org,
kerneljasonxing@...il.com,
chen.dylane@...ux.dev,
willemb@...gle.com,
paul.chaignon@...il.com,
a.s.protopopov@...il.com,
memxor@...il.com,
yatsenko@...a.com,
tklauser@...tanz.ch,
leon.hwang@...ux.dev,
kernel-patches-bot@...com,
linux-kernel@...r.kernel.org,
linux-kselftest@...r.kernel.org
Subject: [PATCH bpf-next v10 3/8] bpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu_array maps
Introduce support for the BPF_F_ALL_CPUS flag in percpu_array maps to
allow updating values for all CPUs with a single value for both
update_elem and update_batch APIs.
Introduce support for the BPF_F_CPU flag in percpu_array maps to allow:
* update value for specified CPU for both update_elem and update_batch
APIs.
* lookup value for specified CPU for both lookup_elem and lookup_batch
APIs.
The BPF_F_CPU flag is passed via:
* map_flags of lookup_elem and update_elem APIs along with embedded cpu
info.
* elem_flags of lookup_batch and update_batch APIs along with embedded
cpu info.
Signed-off-by: Leon Hwang <leon.hwang@...ux.dev>
---
include/linux/bpf.h | 9 +++++++--
kernel/bpf/arraymap.c | 29 +++++++++++++++++++++++------
kernel/bpf/syscall.c | 2 +-
3 files changed, 31 insertions(+), 9 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 65737870f2ea6..c43cdd90bfb12 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2748,7 +2748,7 @@ 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,
@@ -3815,7 +3815,12 @@ bpf_prog_update_insn_ptrs(struct bpf_prog *prog, u32 *offsets, void *image)
static inline bool bpf_map_supports_cpu_flags(enum bpf_map_type map_type)
{
- return false;
+ switch (map_type) {
+ case BPF_MAP_TYPE_PERCPU_ARRAY:
+ return true;
+ default:
+ return false;
+ }
}
static inline int bpf_map_check_op_flags(struct bpf_map *map, u64 flags, u64 allowed_flags)
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 1eeb31c5b317d..67e9e811de3a7 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -307,7 +307,7 @@ 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 map_flags)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
u32 index = *(u32 *)key;
@@ -325,11 +325,18 @@ 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];
+ if (map_flags & BPF_F_CPU) {
+ cpu = map_flags >> 32;
+ copy_map_value(map, value, per_cpu_ptr(pptr, cpu));
+ check_and_init_map_value(map, value);
+ goto unlock;
+ }
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;
}
+unlock:
rcu_read_unlock();
return 0;
}
@@ -398,10 +405,11 @@ int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
struct bpf_array *array = container_of(map, struct bpf_array, map);
u32 index = *(u32 *)key;
void __percpu *pptr;
- int cpu, off = 0;
+ void *ptr, *val;
u32 size;
+ int cpu;
- if (unlikely(map_flags > BPF_EXIST))
+ if (unlikely((map_flags & BPF_F_LOCK) || (u32)map_flags > BPF_F_ALL_CPUS))
/* unknown flags */
return -EINVAL;
@@ -422,11 +430,20 @@ 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];
+ if (map_flags & BPF_F_CPU) {
+ cpu = map_flags >> 32;
+ ptr = per_cpu_ptr(pptr, cpu);
+ copy_map_value(map, ptr, value);
+ bpf_obj_free_fields(array->map.record, ptr);
+ goto unlock;
+ }
for_each_possible_cpu(cpu) {
- copy_map_value_long(map, per_cpu_ptr(pptr, cpu), value + off);
- bpf_obj_free_fields(array->map.record, per_cpu_ptr(pptr, cpu));
- off += size;
+ ptr = per_cpu_ptr(pptr, cpu);
+ val = (map_flags & BPF_F_ALL_CPUS) ? value : value + size * cpu;
+ copy_map_value(map, ptr, val);
+ bpf_obj_free_fields(array->map.record, ptr);
}
+unlock:
rcu_read_unlock();
return 0;
}
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 6edaab858b326..edb7462a34f13 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -318,7 +318,7 @@ 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) {
--
2.51.2
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