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bpf: Introduce BPF_F_CPU and BPF_F_ALL_CPUS flags

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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>
Link: https://lore.kernel.org/r/20260107022022.12843-2-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Leon Hwang
2026-01-07 10:20:16 +08:00
committed by Alexei Starovoitov
parent a8d5067592
commit 2b421662c7
4 changed files with 42 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
include/linux/bpf.h
View File

@@ -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;
}

2
include/uapi/linux/bpf.h
View File

@@ -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 */

29
kernel/bpf/syscall.c
View File

@@ -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)
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 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);

2
tools/include/uapi/linux/bpf.h
View File

@@ -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 */