Introduce support for the BPF_F_ALL_CPUS flag in percpu_array maps to allow updating values for all CPUs with a single value. Introduce support for the BPF_F_CPU flag in percpu_array maps to allow updating value for specified CPU. This enhancement enables: * Efficient update values across all CPUs with a single value when BPF_F_ALL_CPUS is set for update_elem and update_batch APIs. * Targeted update or lookup for a specified CPU when BPF_F_CPU is set. The BPF_F_CPU flag is passed via: * map_flags of lookup_elem and update_elem APIs along with embedded cpu field. * elem_flags of lookup_batch and update_batch APIs along with embedded cpu field. Signed-off-by: Leon Hwang --- include/linux/bpf.h | 3 +- include/uapi/linux/bpf.h | 2 ++ kernel/bpf/arraymap.c | 56 ++++++++++++++++++++++++++-------- kernel/bpf/syscall.c | 27 ++++++++++------ tools/include/uapi/linux/bpf.h | 2 ++ 5 files changed, 67 insertions(+), 23 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 8f6e87f0f3a89..b2191b1e455a6 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2697,7 +2697,8 @@ 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, 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/arraymap.c b/kernel/bpf/arraymap.c index 3d080916faf97..1efa730105e24 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -295,17 +295,24 @@ 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 flags) { struct bpf_array *array = container_of(map, struct bpf_array, map); u32 index = *(u32 *)key; void __percpu *pptr; - int cpu, off = 0; - u32 size; + u32 size, cpu; + int off = 0; if (unlikely(index >= array->map.max_entries)) return -ENOENT; + if (unlikely((u32)flags & ~BPF_F_CPU)) + return -EINVAL; + + cpu = flags >> 32; + if (unlikely((flags & BPF_F_CPU) && cpu >= num_possible_cpus())) + return -ERANGE; + /* per_cpu areas are zero-filled and bpf programs can only * access 'value_size' of them, so copying rounded areas * will not leak any kernel data @@ -313,10 +320,15 @@ 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; + if (flags & BPF_F_CPU) { + copy_map_value_long(map, value, per_cpu_ptr(pptr, cpu)); + check_and_init_map_value(map, value); + } else { + 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; + } } rcu_read_unlock(); return 0; @@ -385,14 +397,22 @@ int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value, u64 map_flags) { struct bpf_array *array = container_of(map, struct bpf_array, map); + const u64 cpu_flags = BPF_F_CPU | BPF_F_ALL_CPUS; u32 index = *(u32 *)key; void __percpu *pptr; - int cpu, off = 0; - u32 size; + u32 size, cpu; + int off = 0; - if (unlikely(map_flags > BPF_EXIST)) + if (unlikely((u32)map_flags > BPF_F_ALL_CPUS)) /* unknown flags */ return -EINVAL; + if (unlikely((map_flags & cpu_flags) == cpu_flags)) + return -EINVAL; + + cpu = map_flags >> 32; + if (unlikely((map_flags & BPF_F_CPU) && cpu >= num_possible_cpus())) + /* invalid cpu */ + return -ERANGE; if (unlikely(index >= array->map.max_entries)) /* all elements were pre-allocated, cannot insert a new one */ @@ -411,10 +431,20 @@ 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]; - for_each_possible_cpu(cpu) { - copy_map_value_long(map, per_cpu_ptr(pptr, cpu), value + off); + if (map_flags & BPF_F_CPU) { + copy_map_value_long(map, per_cpu_ptr(pptr, cpu), value); bpf_obj_free_fields(array->map.record, per_cpu_ptr(pptr, cpu)); - off += size; + } else { + for_each_possible_cpu(cpu) { + copy_map_value_long(map, per_cpu_ptr(pptr, cpu), value + off); + /* same user-provided value is used if + * BPF_F_ALL_CPUS is specified, otherwise value is + * an array of per-cpu values. + */ + if (!(map_flags & BPF_F_ALL_CPUS)) + off += size; + bpf_obj_free_fields(array->map.record, per_cpu_ptr(pptr, cpu)); + } } rcu_read_unlock(); return 0; diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 19f7f5de5e7dc..6251ac9bc7e42 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -131,9 +131,11 @@ 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 || + if (map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY && (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) @@ -314,7 +316,7 @@ 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) { @@ -1656,12 +1658,19 @@ static void *___bpf_copy_key(bpfptr_t ukey, u64 key_size) static int check_map_flags(struct bpf_map *map, u64 flags, bool check_flag) { - if (check_flag && (flags & ~BPF_F_LOCK)) + if (check_flag && ((u32)flags & ~(BPF_F_LOCK | BPF_F_CPU | BPF_F_ALL_CPUS))) 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)) && + map->map_type != BPF_MAP_TYPE_PERCPU_ARRAY) + return -EINVAL; + return 0; } @@ -1695,7 +1704,7 @@ 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 +1771,7 @@ 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); @@ -1962,7 +1971,7 @@ int generic_map_update_batch(struct bpf_map *map, struct file *map_file, 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) @@ -2021,7 +2030,7 @@ int generic_map_lookup_batch(struct bpf_map *map, 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 +2152,7 @@ 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