247 lines
6.1 KiB
C
247 lines
6.1 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
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*/
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#include <linux/types.h>
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#include <linux/bpf.h>
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#include <linux/bpf_local_storage.h>
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#include <uapi/linux/btf.h>
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#include <linux/btf_ids.h>
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DEFINE_BPF_STORAGE_CACHE(cgroup_cache);
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static DEFINE_PER_CPU(int, bpf_cgrp_storage_busy);
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static void bpf_cgrp_storage_lock(void)
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{
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migrate_disable();
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this_cpu_inc(bpf_cgrp_storage_busy);
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}
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static void bpf_cgrp_storage_unlock(void)
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{
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this_cpu_dec(bpf_cgrp_storage_busy);
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migrate_enable();
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}
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static bool bpf_cgrp_storage_trylock(void)
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{
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migrate_disable();
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if (unlikely(this_cpu_inc_return(bpf_cgrp_storage_busy) != 1)) {
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this_cpu_dec(bpf_cgrp_storage_busy);
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migrate_enable();
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return false;
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}
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return true;
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}
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static struct bpf_local_storage __rcu **cgroup_storage_ptr(void *owner)
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{
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struct cgroup *cg = owner;
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return &cg->bpf_cgrp_storage;
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}
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void bpf_cgrp_storage_free(struct cgroup *cgroup)
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{
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struct bpf_local_storage *local_storage;
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bool free_cgroup_storage = false;
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unsigned long flags;
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rcu_read_lock();
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local_storage = rcu_dereference(cgroup->bpf_cgrp_storage);
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if (!local_storage) {
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rcu_read_unlock();
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return;
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}
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bpf_cgrp_storage_lock();
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raw_spin_lock_irqsave(&local_storage->lock, flags);
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free_cgroup_storage = bpf_local_storage_unlink_nolock(local_storage);
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raw_spin_unlock_irqrestore(&local_storage->lock, flags);
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bpf_cgrp_storage_unlock();
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rcu_read_unlock();
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if (free_cgroup_storage)
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kfree_rcu(local_storage, rcu);
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}
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static struct bpf_local_storage_data *
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cgroup_storage_lookup(struct cgroup *cgroup, struct bpf_map *map, bool cacheit_lockit)
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{
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struct bpf_local_storage *cgroup_storage;
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struct bpf_local_storage_map *smap;
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cgroup_storage = rcu_dereference_check(cgroup->bpf_cgrp_storage,
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bpf_rcu_lock_held());
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if (!cgroup_storage)
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return NULL;
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smap = (struct bpf_local_storage_map *)map;
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return bpf_local_storage_lookup(cgroup_storage, smap, cacheit_lockit);
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}
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static void *bpf_cgrp_storage_lookup_elem(struct bpf_map *map, void *key)
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{
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struct bpf_local_storage_data *sdata;
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struct cgroup *cgroup;
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int fd;
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fd = *(int *)key;
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cgroup = cgroup_get_from_fd(fd);
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if (IS_ERR(cgroup))
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return ERR_CAST(cgroup);
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bpf_cgrp_storage_lock();
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sdata = cgroup_storage_lookup(cgroup, map, true);
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bpf_cgrp_storage_unlock();
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cgroup_put(cgroup);
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return sdata ? sdata->data : NULL;
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}
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static long bpf_cgrp_storage_update_elem(struct bpf_map *map, void *key,
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void *value, u64 map_flags)
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{
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struct bpf_local_storage_data *sdata;
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struct cgroup *cgroup;
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int fd;
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fd = *(int *)key;
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cgroup = cgroup_get_from_fd(fd);
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if (IS_ERR(cgroup))
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return PTR_ERR(cgroup);
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bpf_cgrp_storage_lock();
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sdata = bpf_local_storage_update(cgroup, (struct bpf_local_storage_map *)map,
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value, map_flags, GFP_ATOMIC);
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bpf_cgrp_storage_unlock();
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cgroup_put(cgroup);
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return PTR_ERR_OR_ZERO(sdata);
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}
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static int cgroup_storage_delete(struct cgroup *cgroup, struct bpf_map *map)
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{
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struct bpf_local_storage_data *sdata;
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sdata = cgroup_storage_lookup(cgroup, map, false);
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if (!sdata)
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return -ENOENT;
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bpf_selem_unlink(SELEM(sdata), true);
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return 0;
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}
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static long bpf_cgrp_storage_delete_elem(struct bpf_map *map, void *key)
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{
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struct cgroup *cgroup;
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int err, fd;
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fd = *(int *)key;
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cgroup = cgroup_get_from_fd(fd);
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if (IS_ERR(cgroup))
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return PTR_ERR(cgroup);
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bpf_cgrp_storage_lock();
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err = cgroup_storage_delete(cgroup, map);
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bpf_cgrp_storage_unlock();
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cgroup_put(cgroup);
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return err;
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}
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static int notsupp_get_next_key(struct bpf_map *map, void *key, void *next_key)
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{
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return -ENOTSUPP;
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}
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static struct bpf_map *cgroup_storage_map_alloc(union bpf_attr *attr)
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{
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return bpf_local_storage_map_alloc(attr, &cgroup_cache);
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}
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static void cgroup_storage_map_free(struct bpf_map *map)
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{
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bpf_local_storage_map_free(map, &cgroup_cache, NULL);
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}
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/* *gfp_flags* is a hidden argument provided by the verifier */
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BPF_CALL_5(bpf_cgrp_storage_get, struct bpf_map *, map, struct cgroup *, cgroup,
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void *, value, u64, flags, gfp_t, gfp_flags)
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{
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struct bpf_local_storage_data *sdata;
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WARN_ON_ONCE(!bpf_rcu_lock_held());
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if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE))
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return (unsigned long)NULL;
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if (!cgroup)
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return (unsigned long)NULL;
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if (!bpf_cgrp_storage_trylock())
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return (unsigned long)NULL;
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sdata = cgroup_storage_lookup(cgroup, map, true);
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if (sdata)
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goto unlock;
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/* only allocate new storage, when the cgroup is refcounted */
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if (!percpu_ref_is_dying(&cgroup->self.refcnt) &&
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(flags & BPF_LOCAL_STORAGE_GET_F_CREATE))
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sdata = bpf_local_storage_update(cgroup, (struct bpf_local_storage_map *)map,
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value, BPF_NOEXIST, gfp_flags);
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unlock:
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bpf_cgrp_storage_unlock();
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return IS_ERR_OR_NULL(sdata) ? (unsigned long)NULL : (unsigned long)sdata->data;
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}
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BPF_CALL_2(bpf_cgrp_storage_delete, struct bpf_map *, map, struct cgroup *, cgroup)
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{
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int ret;
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WARN_ON_ONCE(!bpf_rcu_lock_held());
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if (!cgroup)
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return -EINVAL;
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if (!bpf_cgrp_storage_trylock())
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return -EBUSY;
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ret = cgroup_storage_delete(cgroup, map);
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bpf_cgrp_storage_unlock();
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return ret;
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}
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const struct bpf_map_ops cgrp_storage_map_ops = {
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.map_meta_equal = bpf_map_meta_equal,
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.map_alloc_check = bpf_local_storage_map_alloc_check,
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.map_alloc = cgroup_storage_map_alloc,
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.map_free = cgroup_storage_map_free,
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.map_get_next_key = notsupp_get_next_key,
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.map_lookup_elem = bpf_cgrp_storage_lookup_elem,
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.map_update_elem = bpf_cgrp_storage_update_elem,
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.map_delete_elem = bpf_cgrp_storage_delete_elem,
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.map_check_btf = bpf_local_storage_map_check_btf,
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.map_btf_id = &bpf_local_storage_map_btf_id[0],
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.map_owner_storage_ptr = cgroup_storage_ptr,
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};
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const struct bpf_func_proto bpf_cgrp_storage_get_proto = {
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.func = bpf_cgrp_storage_get,
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.gpl_only = false,
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.ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
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.arg1_type = ARG_CONST_MAP_PTR,
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.arg2_type = ARG_PTR_TO_BTF_ID,
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.arg2_btf_id = &bpf_cgroup_btf_id[0],
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.arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL,
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.arg4_type = ARG_ANYTHING,
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};
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const struct bpf_func_proto bpf_cgrp_storage_delete_proto = {
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.func = bpf_cgrp_storage_delete,
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.gpl_only = false,
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_CONST_MAP_PTR,
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.arg2_type = ARG_PTR_TO_BTF_ID,
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.arg2_btf_id = &bpf_cgroup_btf_id[0],
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};
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