On Wed, Sep 3, 2025 at 10:04 AM Leon Hwang <leon.hwang@xxxxxxxxx> wrote: > > While adding support for the BPF_F_CPU and BPF_F_ALL_CPUS flags, the data > copying logic of the following percpu map types needs to be updated: > > * percpu_array > * percpu_hash > * lru_percpu_hash > * percpu_cgroup_storage > > Following Andrii’s suggestion[0], this patch refactors the data copying > logic by introducing two helpers: > > * `bpf_percpu_copy_to_user()` > * `bpf_percpu_copy_from_user()` > > This prepares the codebase for the upcoming CPU flag support. > > [0] https://lore.kernel.org/bpf/20250827164509.7401-1-leon.hwang@xxxxxxxxx/ > > Suggested-by: Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> > Signed-off-by: Leon Hwang <leon.hwang@xxxxxxxxx> > --- > include/linux/bpf.h | 29 ++++++++++++++++++++++++++++- > kernel/bpf/arraymap.c | 14 ++------------ > kernel/bpf/hashtab.c | 20 +++----------------- > kernel/bpf/local_storage.c | 18 ++++++------------ > 4 files changed, 39 insertions(+), 42 deletions(-) > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > index 8f6e87f0f3a89..2dc0299a2da50 100644 > --- a/include/linux/bpf.h > +++ b/include/linux/bpf.h > @@ -547,6 +547,34 @@ static inline void copy_map_value_long(struct bpf_map *map, void *dst, void *src > bpf_obj_memcpy(map->record, dst, src, map->value_size, true); > } > > +#ifdef CONFIG_BPF_SYSCALL > +static inline void bpf_percpu_copy_to_user(struct bpf_map *map, void __percpu *pptr, void *value, > + u32 size) > +{ > + int cpu, off = 0; > + > + 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; > + } > +} > + > +void bpf_obj_free_fields(const struct btf_record *rec, void *obj); > + > +static inline void bpf_percpu_copy_from_user(struct bpf_map *map, void __percpu *pptr, void *value, > + u32 size) > +{ > + int cpu, off = 0; > + > + for_each_possible_cpu(cpu) { > + copy_map_value_long(map, per_cpu_ptr(pptr, cpu), value + off); > + bpf_obj_free_fields(map->record, per_cpu_ptr(pptr, cpu)); > + off += size; > + } > +} > +#endif > + > static inline void bpf_obj_swap_uptrs(const struct btf_record *rec, void *dst, void *src) > { > unsigned long *src_uptr, *dst_uptr; > @@ -2417,7 +2445,6 @@ struct btf_record *btf_record_dup(const struct btf_record *rec); > bool btf_record_equal(const struct btf_record *rec_a, const struct btf_record *rec_b); > void bpf_obj_free_timer(const struct btf_record *rec, void *obj); > void bpf_obj_free_workqueue(const struct btf_record *rec, void *obj); > -void bpf_obj_free_fields(const struct btf_record *rec, void *obj); > void __bpf_obj_drop_impl(void *p, const struct btf_record *rec, bool percpu); > > struct bpf_map *bpf_map_get(u32 ufd); > diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c > index 3d080916faf97..6be9c54604503 100644 > --- a/kernel/bpf/arraymap.c > +++ b/kernel/bpf/arraymap.c > @@ -300,7 +300,6 @@ int bpf_percpu_array_copy(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; > u32 size; > > if (unlikely(index >= array->map.max_entries)) > @@ -313,11 +312,7 @@ 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; > - } > + bpf_percpu_copy_to_user(map, pptr, value, size); > rcu_read_unlock(); > return 0; > } > @@ -387,7 +382,6 @@ 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; > u32 size; > > if (unlikely(map_flags > BPF_EXIST)) > @@ -411,11 +405,7 @@ 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); > - bpf_obj_free_fields(array->map.record, per_cpu_ptr(pptr, cpu)); > - off += size; > - } > + bpf_percpu_copy_from_user(map, pptr, value, size); > rcu_read_unlock(); > return 0; > } > diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c > index 71f9931ac64cd..5f0f3c00dbb74 100644 > --- a/kernel/bpf/hashtab.c > +++ b/kernel/bpf/hashtab.c > @@ -944,12 +944,8 @@ static void pcpu_copy_value(struct bpf_htab *htab, void __percpu *pptr, > copy_map_value(&htab->map, this_cpu_ptr(pptr), value); > } else { > u32 size = round_up(htab->map.value_size, 8); > - int off = 0, cpu; > > - for_each_possible_cpu(cpu) { > - copy_map_value_long(&htab->map, per_cpu_ptr(pptr, cpu), value + off); > - off += size; > - } > + bpf_percpu_copy_from_user(&htab->map, pptr, value, size); This is not a refactor. There is a significant change in the logic. Why is it needed? Bug fix or introducing a bug? The names to_user and from_user are wrong. There is no user space memory involved. pw-bot: cr
