From: Leon Hwang <leon.hwang@linux.dev>
To: bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Jiri Olsa <jolsa@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
Song Liu <song@kernel.org>, Eduard Zingerman <eddyz87@gmail.com>,
Martin KaFai Lau <martin.lau@linux.dev>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@fomichev.me>, Hao Luo <haoluo@google.com>,
Shuah Khan <shuah@kernel.org>,
Jason Xing <kerneljasonxing@gmail.com>,
Willem de Bruijn <willemb@google.com>,
Mykyta Yatsenko <yatsenko@meta.com>,
Tao Chen <chen.dylane@linux.dev>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Anton Protopopov <a.s.protopopov@gmail.com>,
Amery Hung <ameryhung@gmail.com>,
Tobias Klauser <tklauser@distanz.ch>, Rong Tao <rongtao@cestc.cn>,
dxu@dxuuu.xyz, deso@posteo.net, Leon Hwang <leon.hwang@linux.dev>,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
kernel-patches-bot@fb.com
Subject: [PATCH bpf-next v13 1/7] bpf: Introduce BPF_F_CPU and BPF_F_ALL_CPUS flags
Date: Wed, 7 Jan 2026 10:20:16 +0800 [thread overview]
Message-ID: <20260107022022.12843-2-leon.hwang@linux.dev> (raw)
In-Reply-To: <20260107022022.12843-1-leon.hwang@linux.dev>
Introduce BPF_F_CPU and BPF_F_ALL_CPUS flags and check them for
following APIs:
* 'map_lookup_elem()'
* 'map_update_elem()'
* 'generic_map_lookup_batch()'
* 'generic_map_update_batch()'
And, get the correct value size for these APIs.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
---
include/linux/bpf.h | 23 ++++++++++++++++++++++-
include/uapi/linux/bpf.h | 2 ++
kernel/bpf/syscall.c | 31 +++++++++++++++++--------------
tools/include/uapi/linux/bpf.h | 2 ++
4 files changed, 43 insertions(+), 15 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index a63e47d2109c..108bab1bda9d 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -3915,14 +3915,35 @@ bpf_prog_update_insn_ptrs(struct bpf_prog *prog, u32 *offsets, void *image)
}
#endif
+static inline bool bpf_map_supports_cpu_flags(enum bpf_map_type map_type)
+{
+ return false;
+}
+
static inline int bpf_map_check_op_flags(struct bpf_map *map, u64 flags, u64 allowed_flags)
{
- if (flags & ~allowed_flags)
+ u32 cpu;
+
+ if ((u32)flags & ~allowed_flags)
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)) {
+ if (!bpf_map_supports_cpu_flags(map->map_type))
+ return -EINVAL;
+ if ((flags & BPF_F_CPU) && (flags & BPF_F_ALL_CPUS))
+ return -EINVAL;
+
+ cpu = flags >> 32;
+ if ((flags & BPF_F_CPU) && cpu >= num_possible_cpus())
+ return -ERANGE;
+ }
+
return 0;
}
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 84ced3ed2d21..2a2ade4be60f 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1384,6 +1384,8 @@ 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/syscall.c b/kernel/bpf/syscall.c
index 6dd2ad2f9e81..e8cfe9d67e64 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -133,12 +133,14 @@ 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)
-{
- 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)
+static u32 bpf_map_value_size(const struct bpf_map *map, u64 flags)
+{
+ if (flags & (BPF_F_CPU | BPF_F_ALL_CPUS))
+ return map->value_size;
+ 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();
else if (IS_FD_MAP(map))
return sizeof(u32);
@@ -1729,7 +1731,7 @@ static int map_lookup_elem(union bpf_attr *attr)
if (!(map_get_sys_perms(map, f) & FMODE_CAN_READ))
return -EPERM;
- err = bpf_map_check_op_flags(map, attr->flags, BPF_F_LOCK);
+ err = bpf_map_check_op_flags(map, attr->flags, BPF_F_LOCK | BPF_F_CPU);
if (err)
return err;
@@ -1737,7 +1739,7 @@ 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);
@@ -1804,7 +1806,7 @@ 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);
@@ -2000,11 +2002,12 @@ int generic_map_update_batch(struct bpf_map *map, struct file *map_file,
void *key, *value;
int err = 0;
- err = bpf_map_check_op_flags(map, attr->batch.elem_flags, BPF_F_LOCK);
+ err = bpf_map_check_op_flags(map, attr->batch.elem_flags,
+ BPF_F_LOCK | BPF_F_CPU | BPF_F_ALL_CPUS);
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)
@@ -2059,11 +2062,11 @@ int generic_map_lookup_batch(struct bpf_map *map,
u32 value_size, cp, max_count;
int err;
- err = bpf_map_check_op_flags(map, attr->batch.elem_flags, BPF_F_LOCK);
+ err = bpf_map_check_op_flags(map, attr->batch.elem_flags, BPF_F_LOCK | BPF_F_CPU);
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)
@@ -2185,7 +2188,7 @@ 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 6b92b0847ec2..b816bc53d2e1 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1384,6 +1384,8 @@ 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 */
--
2.52.0
next prev parent reply other threads:[~2026-01-07 2:25 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-07 2:20 [PATCH bpf-next v13 0/7] bpf: Introduce BPF_F_CPU and BPF_F_ALL_CPUS flags for percpu maps Leon Hwang
2026-01-07 2:20 ` Leon Hwang [this message]
2026-01-07 2:20 ` [PATCH bpf-next v13 2/7] bpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu_array maps Leon Hwang
2026-01-07 2:20 ` [PATCH bpf-next v13 3/7] bpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu_hash and lru_percpu_hash maps Leon Hwang
2026-01-07 2:20 ` [PATCH bpf-next v13 4/7] bpf: Copy map value using copy_map_value_long for percpu_cgroup_storage maps Leon Hwang
2026-01-07 2:20 ` [PATCH bpf-next v13 5/7] bpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support " Leon Hwang
2026-01-07 2:20 ` [PATCH bpf-next v13 6/7] libbpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu maps Leon Hwang
2026-01-07 2:20 ` [PATCH bpf-next v13 7/7] selftests/bpf: Add cases to test BPF_F_CPU and BPF_F_ALL_CPUS flags Leon Hwang
2026-01-07 5:00 ` [PATCH bpf-next v13 0/7] bpf: Introduce BPF_F_CPU and BPF_F_ALL_CPUS flags for percpu maps patchwork-bot+netdevbpf
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