|
| 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 access 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 aother 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 | + |
| 131 | +int bpf_local_storage_map_check_btf(const struct bpf_map *map, |
| 132 | + const struct btf *btf, |
| 133 | + const struct btf_type *key_type, |
| 134 | + const struct btf_type *value_type); |
| 135 | + |
| 136 | +void bpf_selem_link_storage_nolock(struct bpf_local_storage *local_storage, |
| 137 | + struct bpf_local_storage_elem *selem); |
| 138 | + |
| 139 | +bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_storage, |
| 140 | + struct bpf_local_storage_elem *selem, |
| 141 | + bool uncharge_omem); |
| 142 | + |
| 143 | +void bpf_selem_unlink(struct bpf_local_storage_elem *selem); |
| 144 | + |
| 145 | +void bpf_selem_link_map(struct bpf_local_storage_map *smap, |
| 146 | + struct bpf_local_storage_elem *selem); |
| 147 | + |
| 148 | +void bpf_selem_unlink_map(struct bpf_local_storage_elem *selem); |
| 149 | + |
| 150 | +struct bpf_local_storage_elem * |
| 151 | +bpf_selem_alloc(struct bpf_local_storage_map *smap, void *owner, void *value, |
| 152 | + bool charge_mem); |
| 153 | + |
| 154 | +int |
| 155 | +bpf_local_storage_alloc(void *owner, |
| 156 | + struct bpf_local_storage_map *smap, |
| 157 | + struct bpf_local_storage_elem *first_selem); |
| 158 | + |
| 159 | +struct bpf_local_storage_data * |
| 160 | +bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap, |
| 161 | + void *value, u64 map_flags); |
| 162 | + |
| 163 | +#endif /* _BPF_LOCAL_STORAGE_H */ |
0 commit comments