include/linux/bpf_local_storage.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Copyright (c) 2019 Facebook
   4  * Copyright 2020 Google LLC.
   5  */
   6
   7 #ifndef _BPF_LOCAL_STORAGE_H
   8 #define _BPF_LOCAL_STORAGE_H
   9
  10 #include <linux/bpf.h>
  11 #include <linux/rculist.h>
  12 #include <linux/list.h>
  13 #include <linux/hash.h>
  14 #include <linux/types.h>
  15 #include <uapi/linux/btf.h>
  16
  17 #define BPF_LOCAL_STORAGE_CACHE_SIZE    16
  18
  19 struct bpf_local_storage_map_bucket {
  20         struct hlist_head list;
  21         raw_spinlock_t lock;
  22 };
  23
  24 /* Thp map is not the primary owner of a bpf_local_storage_elem.
  25  * Instead, the container object (eg. sk->sk_bpf_storage) is.
  26  *
  27  * The map (bpf_local_storage_map) is for two purposes
  28  * 1. Define the size of the "local storage".  It is
  29  *    the map's value_size.
  30  *
  31  * 2. Maintain a list to keep track of all elems such
  32  *    that they can be cleaned up during the map destruction.
  33  *
  34  * When a bpf local storage is being looked up for a
  35  * particular object,  the "bpf_map" pointer is actually used
  36  * as the "key" to search in the list of elem in
  37  * the respective bpf_local_storage owned by the object.
  38  *
  39  * e.g. sk->sk_bpf_storage is the mini-map with the "bpf_map" pointer
  40  * as the searching key.
  41  */
  42 struct bpf_local_storage_map {
  43         struct bpf_map map;
  44         /* Lookup elem does not require accessing the map.
  45          *
  46          * Updating/Deleting requires a bucket lock to
  47          * link/unlink the elem from the map.  Having
  48          * multiple buckets to improve contention.
  49          */
  50         struct bpf_local_storage_map_bucket *buckets;
  51         u32 bucket_log;
  52         u16 elem_size;
  53         u16 cache_idx;
  54 };
  55
  56 struct bpf_local_storage_data {
  57         /* smap is used as the searching key when looking up
  58          * from the object's bpf_local_storage.
  59          *
  60          * Put it in the same cacheline as the data to minimize
  61          * the number of cachelines accessed during the cache hit case.
  62          */
  63         struct bpf_local_storage_map __rcu *smap;
  64         u8 data[] __aligned(8);
  65 };
  66
  67 /* Linked to bpf_local_storage and bpf_local_storage_map */
  68 struct bpf_local_storage_elem {
  69         struct hlist_node map_node;     /* Linked to bpf_local_storage_map */
  70         struct hlist_node snode;        /* Linked to bpf_local_storage */
  71         struct bpf_local_storage __rcu *local_storage;
  72         struct rcu_head rcu;
  73         /* 8 bytes hole */
  74         /* The data is stored in another cacheline to minimize
  75          * the number of cachelines access during a cache hit.
  76          */
  77         struct bpf_local_storage_data sdata ____cacheline_aligned;
  78 };
  79
  80 struct bpf_local_storage {
  81         struct bpf_local_storage_data __rcu *cache[BPF_LOCAL_STORAGE_CACHE_SIZE];
  82         struct hlist_head list; /* List of bpf_local_storage_elem */
  83         void *owner;            /* The object that owns the above "list" of
  84                                  * bpf_local_storage_elem.
  85                                  */
  86         struct rcu_head rcu;
  87         raw_spinlock_t lock;    /* Protect adding/removing from the "list" */
  88 };
  89
  90 /* U16_MAX is much more than enough for sk local storage
  91  * considering a tcp_sock is ~2k.
  92  */
  93 #define BPF_LOCAL_STORAGE_MAX_VALUE_SIZE                                       \
  94         min_t(u32,                                                             \
  95               (KMALLOC_MAX_SIZE - MAX_BPF_STACK -                              \
  96                sizeof(struct bpf_local_storage_elem)),                         \
  97               (U16_MAX - sizeof(struct bpf_local_storage_elem)))
  98
  99 #define SELEM(_SDATA)                                                          \
 100         container_of((_SDATA), struct bpf_local_storage_elem, sdata)
 101 #define SDATA(_SELEM) (&(_SELEM)->sdata)
 102
 103 #define BPF_LOCAL_STORAGE_CACHE_SIZE    16
 104
 105 struct bpf_local_storage_cache {
 106         spinlock_t idx_lock;
 107         u64 idx_usage_counts[BPF_LOCAL_STORAGE_CACHE_SIZE];
 108 };
 109
 110 #define DEFINE_BPF_STORAGE_CACHE(name)                          \
 111 static struct bpf_local_storage_cache name = {                  \
 112         .idx_lock = __SPIN_LOCK_UNLOCKED(name.idx_lock),        \
 113 }
 114
 115 u16 bpf_local_storage_cache_idx_get(struct bpf_local_storage_cache *cache);
 116 void bpf_local_storage_cache_idx_free(struct bpf_local_storage_cache *cache,
 117                                       u16 idx);
 118
 119 /* Helper functions for bpf_local_storage */
 120 int bpf_local_storage_map_alloc_check(union bpf_attr *attr);
 121
 122 struct bpf_local_storage_map *bpf_local_storage_map_alloc(union bpf_attr *attr);
 123
 124 struct bpf_local_storage_data *
 125 bpf_local_storage_lookup(struct bpf_local_storage *local_storage,
 126                          struct bpf_local_storage_map *smap,
 127                          bool cacheit_lockit);
 128
 129 void bpf_local_storage_map_free(struct bpf_local_storage_map *smap,
 130                                 int __percpu *busy_counter);
 131
 132 int bpf_local_storage_map_check_btf(const struct bpf_map *map,
 133                                     const struct btf *btf,
 134                                     const struct btf_type *key_type,
 135                                     const struct btf_type *value_type);
 136
 137 void bpf_selem_link_storage_nolock(struct bpf_local_storage *local_storage,
 138                                    struct bpf_local_storage_elem *selem);
 139
 140 bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_storage,
 141                                      struct bpf_local_storage_elem *selem,
 142                                      bool uncharge_omem);
 143
 144 void bpf_selem_unlink(struct bpf_local_storage_elem *selem);
 145
 146 void bpf_selem_link_map(struct bpf_local_storage_map *smap,
 147                         struct bpf_local_storage_elem *selem);
 148
 149 void bpf_selem_unlink_map(struct bpf_local_storage_elem *selem);
 150
 151 struct bpf_local_storage_elem *
 152 bpf_selem_alloc(struct bpf_local_storage_map *smap, void *owner, void *value,
 153                 bool charge_mem);
 154
 155 int
 156 bpf_local_storage_alloc(void *owner,
 157                         struct bpf_local_storage_map *smap,
 158                         struct bpf_local_storage_elem *first_selem);
 159
 160 struct bpf_local_storage_data *
 161 bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap,
 162                          void *value, u64 map_flags);
 163
 164 #endif /* _BPF_LOCAL_STORAGE_H */