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Subject[PATCH v4 bpf-next 1/9] bpf: add bpf_map_{value_size,update_value,map_copy_value} functions
From
This commit moves reusable code from map_lookup_elem and map_update_elem
to avoid code duplication in kernel/bpf/syscall.c.

Signed-off-by: Brian Vazquez <brianvv@google.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
---
kernel/bpf/syscall.c | 280 +++++++++++++++++++++++--------------------
1 file changed, 152 insertions(+), 128 deletions(-)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index f9db72a96ec04..08b0b6e40454b 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -129,6 +129,154 @@ static struct bpf_map *find_and_alloc_map(union bpf_attr *attr)
return map;
}

+static u32 bpf_map_value_size(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)
+ return round_up(map->value_size, 8) * num_possible_cpus();
+ else if (IS_FD_MAP(map))
+ return sizeof(u32);
+ else
+ return map->value_size;
+}
+
+static void maybe_wait_bpf_programs(struct bpf_map *map)
+{
+ /* Wait for any running BPF programs to complete so that
+ * userspace, when we return to it, knows that all programs
+ * that could be running use the new map value.
+ */
+ if (map->map_type == BPF_MAP_TYPE_HASH_OF_MAPS ||
+ map->map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS)
+ synchronize_rcu();
+}
+
+static int bpf_map_update_value(struct bpf_map *map, struct fd f, void *key,
+ void *value, __u64 flags)
+{
+ int err;
+
+ /* Need to create a kthread, thus must support schedule */
+ if (bpf_map_is_dev_bound(map)) {
+ return bpf_map_offload_update_elem(map, key, value, flags);
+ } else if (map->map_type == BPF_MAP_TYPE_CPUMAP ||
+ map->map_type == BPF_MAP_TYPE_SOCKHASH ||
+ map->map_type == BPF_MAP_TYPE_SOCKMAP ||
+ map->map_type == BPF_MAP_TYPE_STRUCT_OPS) {
+ return map->ops->map_update_elem(map, key, value, flags);
+ } else if (IS_FD_PROG_ARRAY(map)) {
+ return bpf_fd_array_map_update_elem(map, f.file, key, value,
+ flags);
+ }
+
+ /* must increment bpf_prog_active to avoid kprobe+bpf triggering from
+ * inside bpf map update or delete otherwise deadlocks are possible
+ */
+ preempt_disable();
+ __this_cpu_inc(bpf_prog_active);
+ if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
+ map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH) {
+ err = bpf_percpu_hash_update(map, key, value, flags);
+ } else if (map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY) {
+ err = bpf_percpu_array_update(map, key, value, flags);
+ } else if (map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE) {
+ err = bpf_percpu_cgroup_storage_update(map, key, value,
+ flags);
+ } else if (IS_FD_ARRAY(map)) {
+ rcu_read_lock();
+ err = bpf_fd_array_map_update_elem(map, f.file, key, value,
+ flags);
+ rcu_read_unlock();
+ } else if (map->map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
+ rcu_read_lock();
+ err = bpf_fd_htab_map_update_elem(map, f.file, key, value,
+ flags);
+ rcu_read_unlock();
+ } else if (map->map_type == BPF_MAP_TYPE_REUSEPORT_SOCKARRAY) {
+ /* rcu_read_lock() is not needed */
+ err = bpf_fd_reuseport_array_update_elem(map, key, value,
+ flags);
+ } else if (map->map_type == BPF_MAP_TYPE_QUEUE ||
+ map->map_type == BPF_MAP_TYPE_STACK) {
+ err = map->ops->map_push_elem(map, value, flags);
+ } else {
+ rcu_read_lock();
+ err = map->ops->map_update_elem(map, key, value, flags);
+ rcu_read_unlock();
+ }
+ __this_cpu_dec(bpf_prog_active);
+ preempt_enable();
+ maybe_wait_bpf_programs(map);
+
+ return err;
+}
+
+static int bpf_map_copy_value(struct bpf_map *map, void *key, void *value,
+ __u64 flags)
+{
+ void *ptr;
+ int err;
+
+ if (bpf_map_is_dev_bound(map)) {
+ err = bpf_map_offload_lookup_elem(map, key, value);
+ return err;
+ }
+
+ preempt_disable();
+ this_cpu_inc(bpf_prog_active);
+ if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
+ 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);
+ } 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) {
+ err = bpf_stackmap_copy(map, key, value);
+ } else if (IS_FD_ARRAY(map) || IS_FD_PROG_ARRAY(map)) {
+ err = bpf_fd_array_map_lookup_elem(map, key, value);
+ } else if (IS_FD_HASH(map)) {
+ err = bpf_fd_htab_map_lookup_elem(map, key, value);
+ } else if (map->map_type == BPF_MAP_TYPE_REUSEPORT_SOCKARRAY) {
+ err = bpf_fd_reuseport_array_lookup_elem(map, key, value);
+ } else if (map->map_type == BPF_MAP_TYPE_QUEUE ||
+ map->map_type == BPF_MAP_TYPE_STACK) {
+ err = map->ops->map_peek_elem(map, value);
+ } else if (map->map_type == BPF_MAP_TYPE_STRUCT_OPS) {
+ /* struct_ops map requires directly updating "value" */
+ err = bpf_struct_ops_map_sys_lookup_elem(map, key, value);
+ } else {
+ rcu_read_lock();
+ if (map->ops->map_lookup_elem_sys_only)
+ ptr = map->ops->map_lookup_elem_sys_only(map, key);
+ else
+ ptr = map->ops->map_lookup_elem(map, key);
+ if (IS_ERR(ptr)) {
+ err = PTR_ERR(ptr);
+ } else if (!ptr) {
+ err = -ENOENT;
+ } else {
+ err = 0;
+ if (flags & BPF_F_LOCK)
+ /* lock 'ptr' and copy everything but lock */
+ copy_map_value_locked(map, value, ptr, true);
+ else
+ copy_map_value(map, value, ptr);
+ /* mask lock, since value wasn't zero inited */
+ check_and_init_map_lock(map, value);
+ }
+ rcu_read_unlock();
+ }
+
+ this_cpu_dec(bpf_prog_active);
+ preempt_enable();
+ maybe_wait_bpf_programs(map);
+
+ return err;
+}
+
static void *__bpf_map_area_alloc(u64 size, int numa_node, bool mmapable)
{
/* We really just want to fail instead of triggering OOM killer
@@ -827,7 +975,7 @@ static int map_lookup_elem(union bpf_attr *attr)
void __user *uvalue = u64_to_user_ptr(attr->value);
int ufd = attr->map_fd;
struct bpf_map *map;
- void *key, *value, *ptr;
+ void *key, *value;
u32 value_size;
struct fd f;
int err;
@@ -859,75 +1007,14 @@ static int map_lookup_elem(union bpf_attr *attr)
goto err_put;
}

- 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)
- value_size = round_up(map->value_size, 8) * num_possible_cpus();
- else if (IS_FD_MAP(map))
- value_size = sizeof(u32);
- else
- value_size = map->value_size;
+ value_size = bpf_map_value_size(map);

err = -ENOMEM;
value = kmalloc(value_size, GFP_USER | __GFP_NOWARN);
if (!value)
goto free_key;

- if (bpf_map_is_dev_bound(map)) {
- err = bpf_map_offload_lookup_elem(map, key, value);
- goto done;
- }
-
- preempt_disable();
- this_cpu_inc(bpf_prog_active);
- if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
- 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);
- } 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) {
- err = bpf_stackmap_copy(map, key, value);
- } else if (IS_FD_ARRAY(map) || IS_FD_PROG_ARRAY(map)) {
- err = bpf_fd_array_map_lookup_elem(map, key, value);
- } else if (IS_FD_HASH(map)) {
- err = bpf_fd_htab_map_lookup_elem(map, key, value);
- } else if (map->map_type == BPF_MAP_TYPE_REUSEPORT_SOCKARRAY) {
- err = bpf_fd_reuseport_array_lookup_elem(map, key, value);
- } else if (map->map_type == BPF_MAP_TYPE_QUEUE ||
- map->map_type == BPF_MAP_TYPE_STACK) {
- err = map->ops->map_peek_elem(map, value);
- } else if (map->map_type == BPF_MAP_TYPE_STRUCT_OPS) {
- /* struct_ops map requires directly updating "value" */
- err = bpf_struct_ops_map_sys_lookup_elem(map, key, value);
- } else {
- rcu_read_lock();
- if (map->ops->map_lookup_elem_sys_only)
- ptr = map->ops->map_lookup_elem_sys_only(map, key);
- else
- ptr = map->ops->map_lookup_elem(map, key);
- if (IS_ERR(ptr)) {
- err = PTR_ERR(ptr);
- } else if (!ptr) {
- err = -ENOENT;
- } else {
- err = 0;
- if (attr->flags & BPF_F_LOCK)
- /* lock 'ptr' and copy everything but lock */
- copy_map_value_locked(map, value, ptr, true);
- else
- copy_map_value(map, value, ptr);
- /* mask lock, since value wasn't zero inited */
- check_and_init_map_lock(map, value);
- }
- rcu_read_unlock();
- }
- this_cpu_dec(bpf_prog_active);
- preempt_enable();
-
-done:
+ err = bpf_map_copy_value(map, key, value, attr->flags);
if (err)
goto free_value;

@@ -946,16 +1033,6 @@ static int map_lookup_elem(union bpf_attr *attr)
return err;
}

-static void maybe_wait_bpf_programs(struct bpf_map *map)
-{
- /* Wait for any running BPF programs to complete so that
- * userspace, when we return to it, knows that all programs
- * that could be running use the new map value.
- */
- if (map->map_type == BPF_MAP_TYPE_HASH_OF_MAPS ||
- map->map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS)
- synchronize_rcu();
-}

#define BPF_MAP_UPDATE_ELEM_LAST_FIELD flags

@@ -1011,61 +1088,8 @@ static int map_update_elem(union bpf_attr *attr)
if (copy_from_user(value, uvalue, value_size) != 0)
goto free_value;

- /* Need to create a kthread, thus must support schedule */
- if (bpf_map_is_dev_bound(map)) {
- err = bpf_map_offload_update_elem(map, key, value, attr->flags);
- goto out;
- } else if (map->map_type == BPF_MAP_TYPE_CPUMAP ||
- map->map_type == BPF_MAP_TYPE_SOCKHASH ||
- map->map_type == BPF_MAP_TYPE_SOCKMAP ||
- map->map_type == BPF_MAP_TYPE_STRUCT_OPS) {
- err = map->ops->map_update_elem(map, key, value, attr->flags);
- goto out;
- } else if (IS_FD_PROG_ARRAY(map)) {
- err = bpf_fd_array_map_update_elem(map, f.file, key, value,
- attr->flags);
- goto out;
- }
+ err = bpf_map_update_value(map, f, key, value, attr->flags);

- /* must increment bpf_prog_active to avoid kprobe+bpf triggering from
- * inside bpf map update or delete otherwise deadlocks are possible
- */
- preempt_disable();
- __this_cpu_inc(bpf_prog_active);
- if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
- map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH) {
- err = bpf_percpu_hash_update(map, key, value, attr->flags);
- } else if (map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY) {
- err = bpf_percpu_array_update(map, key, value, attr->flags);
- } else if (map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE) {
- err = bpf_percpu_cgroup_storage_update(map, key, value,
- attr->flags);
- } else if (IS_FD_ARRAY(map)) {
- rcu_read_lock();
- err = bpf_fd_array_map_update_elem(map, f.file, key, value,
- attr->flags);
- rcu_read_unlock();
- } else if (map->map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
- rcu_read_lock();
- err = bpf_fd_htab_map_update_elem(map, f.file, key, value,
- attr->flags);
- rcu_read_unlock();
- } else if (map->map_type == BPF_MAP_TYPE_REUSEPORT_SOCKARRAY) {
- /* rcu_read_lock() is not needed */
- err = bpf_fd_reuseport_array_update_elem(map, key, value,
- attr->flags);
- } else if (map->map_type == BPF_MAP_TYPE_QUEUE ||
- map->map_type == BPF_MAP_TYPE_STACK) {
- err = map->ops->map_push_elem(map, value, attr->flags);
- } else {
- rcu_read_lock();
- err = map->ops->map_update_elem(map, key, value, attr->flags);
- rcu_read_unlock();
- }
- __this_cpu_dec(bpf_prog_active);
- preempt_enable();
- maybe_wait_bpf_programs(map);
-out:
free_value:
kfree(value);
free_key:
--
2.25.0.rc1.283.g88dfdc4193-goog
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