/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (c) 2019 Facebook
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* Copyright 2020 Google LLC.
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*/
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#ifndef _BPF_LOCAL_STORAGE_H
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#define _BPF_LOCAL_STORAGE_H
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#include <linux/bpf.h>
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#include <linux/rculist.h>
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#include <linux/list.h>
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#include <linux/hash.h>
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#include <linux/types.h>
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#include <uapi/linux/btf.h>
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#define BPF_LOCAL_STORAGE_CACHE_SIZE 16
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struct bpf_local_storage_map_bucket {
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struct hlist_head list;
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raw_spinlock_t lock;
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};
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/* Thp map is not the primary owner of a bpf_local_storage_elem.
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* Instead, the container object (eg. sk->sk_bpf_storage) is.
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*
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* The map (bpf_local_storage_map) is for two purposes
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* 1. Define the size of the "local storage". It is
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* the map's value_size.
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*
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* 2. Maintain a list to keep track of all elems such
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* that they can be cleaned up during the map destruction.
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*
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* When a bpf local storage is being looked up for a
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* particular object, the "bpf_map" pointer is actually used
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* as the "key" to search in the list of elem in
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* the respective bpf_local_storage owned by the object.
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*
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* e.g. sk->sk_bpf_storage is the mini-map with the "bpf_map" pointer
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* as the searching key.
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*/
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struct bpf_local_storage_map {
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struct bpf_map map;
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/* Lookup elem does not require accessing the map.
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*
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* Updating/Deleting requires a bucket lock to
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* link/unlink the elem from the map. Having
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* multiple buckets to improve contention.
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*/
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struct bpf_local_storage_map_bucket *buckets;
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u32 bucket_log;
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u16 elem_size;
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u16 cache_idx;
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};
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struct bpf_local_storage_data {
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/* smap is used as the searching key when looking up
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* from the object's bpf_local_storage.
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*
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* Put it in the same cacheline as the data to minimize
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* the number of cachelines access during the cache hit case.
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*/
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struct bpf_local_storage_map __rcu *smap;
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u8 data[] __aligned(8);
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};
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/* Linked to bpf_local_storage and bpf_local_storage_map */
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struct bpf_local_storage_elem {
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struct hlist_node map_node; /* Linked to bpf_local_storage_map */
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struct hlist_node snode; /* Linked to bpf_local_storage */
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struct bpf_local_storage __rcu *local_storage;
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struct rcu_head rcu;
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/* 8 bytes hole */
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/* The data is stored in aother cacheline to minimize
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* the number of cachelines access during a cache hit.
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*/
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struct bpf_local_storage_data sdata ____cacheline_aligned;
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};
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struct bpf_local_storage {
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struct bpf_local_storage_data __rcu *cache[BPF_LOCAL_STORAGE_CACHE_SIZE];
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struct hlist_head list; /* List of bpf_local_storage_elem */
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void *owner; /* The object that owns the above "list" of
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* bpf_local_storage_elem.
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*/
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struct rcu_head rcu;
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raw_spinlock_t lock; /* Protect adding/removing from the "list" */
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};
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/* U16_MAX is much more than enough for sk local storage
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* considering a tcp_sock is ~2k.
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*/
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#define BPF_LOCAL_STORAGE_MAX_VALUE_SIZE \
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min_t(u32, \
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(KMALLOC_MAX_SIZE - MAX_BPF_STACK - \
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sizeof(struct bpf_local_storage_elem)), \
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(U16_MAX - sizeof(struct bpf_local_storage_elem)))
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#define SELEM(_SDATA) \
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container_of((_SDATA), struct bpf_local_storage_elem, sdata)
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#define SDATA(_SELEM) (&(_SELEM)->sdata)
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#define BPF_LOCAL_STORAGE_CACHE_SIZE 16
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struct bpf_local_storage_cache {
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spinlock_t idx_lock;
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u64 idx_usage_counts[BPF_LOCAL_STORAGE_CACHE_SIZE];
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};
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#define DEFINE_BPF_STORAGE_CACHE(name) \
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static struct bpf_local_storage_cache name = { \
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.idx_lock = __SPIN_LOCK_UNLOCKED(name.idx_lock), \
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}
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u16 bpf_local_storage_cache_idx_get(struct bpf_local_storage_cache *cache);
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void bpf_local_storage_cache_idx_free(struct bpf_local_storage_cache *cache,
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u16 idx);
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/* Helper functions for bpf_local_storage */
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int bpf_local_storage_map_alloc_check(union bpf_attr *attr);
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struct bpf_local_storage_map *bpf_local_storage_map_alloc(union bpf_attr *attr);
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struct bpf_local_storage_data *
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bpf_local_storage_lookup(struct bpf_local_storage *local_storage,
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struct bpf_local_storage_map *smap,
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bool cacheit_lockit);
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void bpf_local_storage_map_free(struct bpf_local_storage_map *smap);
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int bpf_local_storage_map_check_btf(const struct bpf_map *map,
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const struct btf *btf,
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const struct btf_type *key_type,
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const struct btf_type *value_type);
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void bpf_selem_link_storage_nolock(struct bpf_local_storage *local_storage,
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struct bpf_local_storage_elem *selem);
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bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_storage,
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struct bpf_local_storage_elem *selem,
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bool uncharge_omem);
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void bpf_selem_unlink(struct bpf_local_storage_elem *selem);
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void bpf_selem_link_map(struct bpf_local_storage_map *smap,
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struct bpf_local_storage_elem *selem);
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void bpf_selem_unlink_map(struct bpf_local_storage_elem *selem);
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struct bpf_local_storage_elem *
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bpf_selem_alloc(struct bpf_local_storage_map *smap, void *owner, void *value,
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bool charge_mem);
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int
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bpf_local_storage_alloc(void *owner,
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struct bpf_local_storage_map *smap,
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struct bpf_local_storage_elem *first_selem);
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struct bpf_local_storage_data *
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bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap,
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void *value, u64 map_flags);
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#endif /* _BPF_LOCAL_STORAGE_H */
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