From: Leon Hwang <leon.hwang@linux.dev>
To: bpf@vger.kernel.org
Cc: ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net,
jolsa@kernel.org, yonghong.song@linux.dev, song@kernel.org,
eddyz87@gmail.com, dxu@dxuuu.xyz, deso@posteo.net,
leon.hwang@linux.dev, kernel-patches-bot@fb.com
Subject: [PATCH bpf-next v6 2/7] bpf: Introduce BPF_F_CPU and BPF_F_ALL_CPUS flags
Date: Tue, 9 Sep 2025 22:14:16 +0800 [thread overview]
Message-ID: <20250909141422.45450-3-leon.hwang@linux.dev> (raw)
In-Reply-To: <20250909141422.45450-1-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.
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
---
include/linux/bpf.h | 22 ++++++++++++++++++
include/uapi/linux/bpf.h | 2 ++
kernel/bpf/syscall.c | 42 ++++++++++++++++++++++------------
tools/include/uapi/linux/bpf.h | 2 ++
4 files changed, 54 insertions(+), 14 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 8f6e87f0f3a89..60c235836987d 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -3709,4 +3709,26 @@ int bpf_prog_get_file_line(struct bpf_prog *prog, unsigned long ip, const char *
const char **linep, int *nump);
struct bpf_prog *bpf_prog_find_from_stack(void);
+static inline int bpf_map_check_cpu_flags(u64 flags, bool check_all_cpus_flag)
+{
+ const u64 cpu_flags = BPF_F_CPU | BPF_F_ALL_CPUS;
+ u32 cpu;
+
+ if (check_all_cpus_flag) {
+ if (unlikely((u32)flags > BPF_F_ALL_CPUS))
+ return -EINVAL;
+ if (unlikely((flags & cpu_flags) == cpu_flags))
+ return -EINVAL;
+ } else {
+ if (unlikely((u32)flags & ~BPF_F_CPU))
+ return -EINVAL;
+ }
+
+ cpu = flags >> 32;
+ if (unlikely((flags & BPF_F_CPU) && cpu >= num_possible_cpus()))
+ return -ERANGE;
+
+ return 0;
+}
+
#endif /* _LINUX_BPF_H */
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/syscall.c b/kernel/bpf/syscall.c
index f5448e00a2e8f..db841b38f0c22 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -131,23 +131,36 @@ bool bpf_map_write_active(const struct bpf_map *map)
return atomic64_read(&map->writecnt) != 0;
}
+static bool bpf_map_supports_cpu_flags(enum bpf_map_type map_type)
+{
+ return false;
+}
+
static int bpf_map_check_op_flags(struct bpf_map *map, u64 flags, u64 allowed_flags)
{
- if (flags & ~allowed_flags)
+ 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)) && !bpf_map_supports_cpu_flags(map->map_type))
+ return -EINVAL;
+
return 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 ||
- 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)
+ if (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();
else if (IS_FD_MAP(map))
return sizeof(u32);
@@ -1687,7 +1700,7 @@ 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;
@@ -1695,7 +1708,7 @@ 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 +1775,7 @@ 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);
@@ -1958,11 +1971,12 @@ 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)
@@ -2017,11 +2031,11 @@ 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)
@@ -2143,7 +2157,7 @@ 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
next prev parent reply other threads:[~2025-09-09 14:14 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-09 14:14 [PATCH bpf-next v6 0/7] bpf: Introduce BPF_F_CPU and BPF_F_ALL_CPUS flags for percpu maps Leon Hwang
2025-09-09 14:14 ` [PATCH bpf-next v6 1/7] bpf: Introduce internal bpf_map_check_op_flags helper function Leon Hwang
2025-09-09 14:14 ` Leon Hwang [this message]
2025-09-09 23:07 ` [PATCH bpf-next v6 2/7] bpf: Introduce BPF_F_CPU and BPF_F_ALL_CPUS flags Alexei Starovoitov
2025-09-10 2:20 ` Leon Hwang
2025-09-09 14:14 ` [PATCH bpf-next v6 3/7] bpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu_array maps Leon Hwang
2025-09-09 14:14 ` [PATCH bpf-next v6 4/7] bpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu_hash and lru_percpu_hash maps Leon Hwang
2025-09-09 14:14 ` [PATCH bpf-next v6 5/7] bpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu_cgroup_storage maps Leon Hwang
2025-09-09 14:14 ` [PATCH bpf-next v6 6/7] libbpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu maps Leon Hwang
2025-09-09 14:14 ` [PATCH bpf-next v6 7/7] selftests/bpf: Add cases to test BPF_F_CPU and BPF_F_ALL_CPUS flags Leon Hwang
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