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/filter.h>
  12 #include <linux/rculist.h>
  13 #include <linux/list.h>
  14 #include <linux/hash.h>
  15 #include <linux/types.h>
  16 #include <linux/bpf_mem_alloc.h>
  17 #include <uapi/linux/btf.h>
  18
  19 #define BPF_LOCAL_STORAGE_CACHE_SIZE    16
  20
  21 #define bpf_rcu_lock_held()                                                    \
  22         (rcu_read_lock_held() || rcu_read_lock_trace_held() ||                 \
  23          rcu_read_lock_bh_held())
  24 struct bpf_local_storage_map_bucket {
  25         struct hlist_head list;
  26         raw_spinlock_t lock;
  27 };
  28
  29 /* Thp map is not the primary owner of a bpf_local_storage_elem.
  30  * Instead, the container object (eg. sk->sk_bpf_storage) is.
  31  *
  32  * The map (bpf_local_storage_map) is for two purposes
  33  * 1. Define the size of the "local storage".  It is
  34  *    the map's value_size.
  35  *
  36  * 2. Maintain a list to keep track of all elems such
  37  *    that they can be cleaned up during the map destruction.
  38  *
  39  * When a bpf local storage is being looked up for a
  40  * particular object,  the "bpf_map" pointer is actually used
  41  * as the "key" to search in the list of elem in
  42  * the respective bpf_local_storage owned by the object.
  43  *
  44  * e.g. sk->sk_bpf_storage is the mini-map with the "bpf_map" pointer
  45  * as the searching key.
  46  */
  47 struct bpf_local_storage_map {
  48         struct bpf_map map;
  49         /* Lookup elem does not require accessing the map.
  50          *
  51          * Updating/Deleting requires a bucket lock to
  52          * link/unlink the elem from the map.  Having
  53          * multiple buckets to improve contention.
  54          */
  55         struct bpf_local_storage_map_bucket *buckets;
  56         u32 bucket_log;
  57         u16 elem_size;
  58         u16 cache_idx;
  59         struct bpf_mem_alloc selem_ma;
  60         struct bpf_mem_alloc storage_ma;
  61         bool bpf_ma;
  62 };
  63
  64 struct bpf_local_storage_data {
  65         /* smap is used as the searching key when looking up
  66          * from the object's bpf_local_storage.
  67          *
  68          * Put it in the same cacheline as the data to minimize
  69          * the number of cachelines accessed during the cache hit case.
  70          */
  71         struct bpf_local_storage_map __rcu *smap;
  72         u8 data[] __aligned(8);
  73 };
  74
  75 /* Linked to bpf_local_storage and bpf_local_storage_map */
  76 struct bpf_local_storage_elem {
  77         struct hlist_node map_node;     /* Linked to bpf_local_storage_map */
  78         struct hlist_node snode;        /* Linked to bpf_local_storage */
  79         struct bpf_local_storage __rcu *local_storage;
  80         struct rcu_head rcu;
  81         /* 8 bytes hole */
  82         /* The data is stored in another cacheline to minimize
  83          * the number of cachelines access during a cache hit.
  84          */
  85         struct bpf_local_storage_data sdata ____cacheline_aligned;
  86 };
  87
  88 struct bpf_local_storage {
  89         struct bpf_local_storage_data __rcu *cache[BPF_LOCAL_STORAGE_CACHE_SIZE];
  90         struct bpf_local_storage_map __rcu *smap;
  91         struct hlist_head list; /* List of bpf_local_storage_elem */
  92         void *owner;            /* The object that owns the above "list" of
  93                                  * bpf_local_storage_elem.
  94                                  */
  95         struct rcu_head rcu;
  96         raw_spinlock_t lock;    /* Protect adding/removing from the "list" */
  97 };
  98
  99 /* U16_MAX is much more than enough for sk local storage
 100  * considering a tcp_sock is ~2k.
 101  */
 102 #define BPF_LOCAL_STORAGE_MAX_VALUE_SIZE                                       \
 103         min_t(u32,                                                             \
 104               (KMALLOC_MAX_SIZE - MAX_BPF_STACK -                              \
 105                sizeof(struct bpf_local_storage_elem)),                         \
 106               (U16_MAX - sizeof(struct bpf_local_storage_elem)))
 107
 108 #define SELEM(_SDATA)                                                          \
 109         container_of((_SDATA), struct bpf_local_storage_elem, sdata)
 110 #define SDATA(_SELEM) (&(_SELEM)->sdata)
 111
 112 #define BPF_LOCAL_STORAGE_CACHE_SIZE    16
 113
 114 struct bpf_local_storage_cache {
 115         spinlock_t idx_lock;
 116         u64 idx_usage_counts[BPF_LOCAL_STORAGE_CACHE_SIZE];
 117 };
 118
 119 #define DEFINE_BPF_STORAGE_CACHE(name)                          \
 120 static struct bpf_local_storage_cache name = {                  \
 121         .idx_lock = __SPIN_LOCK_UNLOCKED(name.idx_lock),        \
 122 }
 123
 124 /* Helper functions for bpf_local_storage */
 125 int bpf_local_storage_map_alloc_check(union bpf_attr *attr);
 126
 127 struct bpf_map *
 128 bpf_local_storage_map_alloc(union bpf_attr *attr,
 129                             struct bpf_local_storage_cache *cache,
 130                             bool bpf_ma);
 131
 132 struct bpf_local_storage_data *
 133 bpf_local_storage_lookup(struct bpf_local_storage *local_storage,
 134                          struct bpf_local_storage_map *smap,
 135                          bool cacheit_lockit);
 136
 137 void bpf_local_storage_destroy(struct bpf_local_storage *local_storage);
 138
 139 void bpf_local_storage_map_free(struct bpf_map *map,
 140                                 struct bpf_local_storage_cache *cache,
 141                                 int __percpu *busy_counter);
 142
 143 int bpf_local_storage_map_check_btf(const struct bpf_map *map,
 144                                     const struct btf *btf,
 145                                     const struct btf_type *key_type,
 146                                     const struct btf_type *value_type);
 147
 148 void bpf_selem_link_storage_nolock(struct bpf_local_storage *local_storage,
 149                                    struct bpf_local_storage_elem *selem);
 150
 151 void bpf_selem_unlink(struct bpf_local_storage_elem *selem, bool reuse_now);
 152
 153 void bpf_selem_link_map(struct bpf_local_storage_map *smap,
 154                         struct bpf_local_storage_elem *selem);
 155
 156 struct bpf_local_storage_elem *
 157 bpf_selem_alloc(struct bpf_local_storage_map *smap, void *owner, void *value,
 158                 bool charge_mem, gfp_t gfp_flags);
 159
 160 void bpf_selem_free(struct bpf_local_storage_elem *selem,
 161                     struct bpf_local_storage_map *smap,
 162                     bool reuse_now);
 163
 164 int
 165 bpf_local_storage_alloc(void *owner,
 166                         struct bpf_local_storage_map *smap,
 167                         struct bpf_local_storage_elem *first_selem,
 168                         gfp_t gfp_flags);
 169
 170 struct bpf_local_storage_data *
 171 bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap,
 172                          void *value, u64 map_flags, gfp_t gfp_flags);
 173
 174 u64 bpf_local_storage_map_mem_usage(const struct bpf_map *map);
 175
 176 #endif /* _BPF_LOCAL_STORAGE_H */