1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * queue_stack_maps.c: BPF queue and stack maps 4 * 5 * Copyright (c) 2018 Politecnico di Torino 6 */ 7 #include <linux/bpf.h> 8 #include <linux/list.h> 9 #include <linux/slab.h> 10 #include <linux/btf_ids.h> 11 #include "percpu_freelist.h" 12 13 #define QUEUE_STACK_CREATE_FLAG_MASK \ 14 (BPF_F_NUMA_NODE | BPF_F_ACCESS_MASK) 15 16 struct bpf_queue_stack { 17 struct bpf_map map; 18 raw_spinlock_t lock; 19 u32 head, tail; 20 u32 size; /* max_entries + 1 */ 21 22 char elements[] __aligned(8); 23 }; 24 25 static struct bpf_queue_stack *bpf_queue_stack(struct bpf_map *map) 26 { 27 return container_of(map, struct bpf_queue_stack, map); 28 } 29 30 static bool queue_stack_map_is_empty(struct bpf_queue_stack *qs) 31 { 32 return qs->head == qs->tail; 33 } 34 35 static bool queue_stack_map_is_full(struct bpf_queue_stack *qs) 36 { 37 u32 head = qs->head + 1; 38 39 if (unlikely(head >= qs->size)) 40 head = 0; 41 42 return head == qs->tail; 43 } 44 45 /* Called from syscall */ 46 static int queue_stack_map_alloc_check(union bpf_attr *attr) 47 { 48 /* check sanity of attributes */ 49 if (attr->max_entries == 0 || attr->key_size != 0 || 50 attr->value_size == 0 || 51 attr->map_flags & ~QUEUE_STACK_CREATE_FLAG_MASK || 52 !bpf_map_flags_access_ok(attr->map_flags)) 53 return -EINVAL; 54 55 if (attr->value_size > KMALLOC_MAX_SIZE) 56 /* if value_size is bigger, the user space won't be able to 57 * access the elements. 58 */ 59 return -E2BIG; 60 61 return 0; 62 } 63 64 static struct bpf_map *queue_stack_map_alloc(union bpf_attr *attr) 65 { 66 int numa_node = bpf_map_attr_numa_node(attr); 67 struct bpf_queue_stack *qs; 68 u64 size, queue_size; 69 70 size = (u64) attr->max_entries + 1; 71 queue_size = sizeof(*qs) + size * attr->value_size; 72 73 qs = bpf_map_area_alloc(queue_size, numa_node); 74 if (!qs) 75 return ERR_PTR(-ENOMEM); 76 77 bpf_map_init_from_attr(&qs->map, attr); 78 79 qs->size = size; 80 81 raw_spin_lock_init(&qs->lock); 82 83 return &qs->map; 84 } 85 86 /* Called when map->refcnt goes to zero, either from workqueue or from syscall */ 87 static void queue_stack_map_free(struct bpf_map *map) 88 { 89 struct bpf_queue_stack *qs = bpf_queue_stack(map); 90 91 bpf_map_area_free(qs); 92 } 93 94 static long __queue_map_get(struct bpf_map *map, void *value, bool delete) 95 { 96 struct bpf_queue_stack *qs = bpf_queue_stack(map); 97 unsigned long flags; 98 int err = 0; 99 void *ptr; 100 101 raw_spin_lock_irqsave(&qs->lock, flags); 102 103 if (queue_stack_map_is_empty(qs)) { 104 memset(value, 0, qs->map.value_size); 105 err = -ENOENT; 106 goto out; 107 } 108 109 ptr = &qs->elements[qs->tail * qs->map.value_size]; 110 memcpy(value, ptr, qs->map.value_size); 111 112 if (delete) { 113 if (unlikely(++qs->tail >= qs->size)) 114 qs->tail = 0; 115 } 116 117 out: 118 raw_spin_unlock_irqrestore(&qs->lock, flags); 119 return err; 120 } 121 122 123 static long __stack_map_get(struct bpf_map *map, void *value, bool delete) 124 { 125 struct bpf_queue_stack *qs = bpf_queue_stack(map); 126 unsigned long flags; 127 int err = 0; 128 void *ptr; 129 u32 index; 130 131 raw_spin_lock_irqsave(&qs->lock, flags); 132 133 if (queue_stack_map_is_empty(qs)) { 134 memset(value, 0, qs->map.value_size); 135 err = -ENOENT; 136 goto out; 137 } 138 139 index = qs->head - 1; 140 if (unlikely(index >= qs->size)) 141 index = qs->size - 1; 142 143 ptr = &qs->elements[index * qs->map.value_size]; 144 memcpy(value, ptr, qs->map.value_size); 145 146 if (delete) 147 qs->head = index; 148 149 out: 150 raw_spin_unlock_irqrestore(&qs->lock, flags); 151 return err; 152 } 153 154 /* Called from syscall or from eBPF program */ 155 static long queue_map_peek_elem(struct bpf_map *map, void *value) 156 { 157 return __queue_map_get(map, value, false); 158 } 159 160 /* Called from syscall or from eBPF program */ 161 static long stack_map_peek_elem(struct bpf_map *map, void *value) 162 { 163 return __stack_map_get(map, value, false); 164 } 165 166 /* Called from syscall or from eBPF program */ 167 static long queue_map_pop_elem(struct bpf_map *map, void *value) 168 { 169 return __queue_map_get(map, value, true); 170 } 171 172 /* Called from syscall or from eBPF program */ 173 static long stack_map_pop_elem(struct bpf_map *map, void *value) 174 { 175 return __stack_map_get(map, value, true); 176 } 177 178 /* Called from syscall or from eBPF program */ 179 static long queue_stack_map_push_elem(struct bpf_map *map, void *value, 180 u64 flags) 181 { 182 struct bpf_queue_stack *qs = bpf_queue_stack(map); 183 unsigned long irq_flags; 184 int err = 0; 185 void *dst; 186 187 /* BPF_EXIST is used to force making room for a new element in case the 188 * map is full 189 */ 190 bool replace = (flags & BPF_EXIST); 191 192 /* Check supported flags for queue and stack maps */ 193 if (flags & BPF_NOEXIST || flags > BPF_EXIST) 194 return -EINVAL; 195 196 raw_spin_lock_irqsave(&qs->lock, irq_flags); 197 198 if (queue_stack_map_is_full(qs)) { 199 if (!replace) { 200 err = -E2BIG; 201 goto out; 202 } 203 /* advance tail pointer to overwrite oldest element */ 204 if (unlikely(++qs->tail >= qs->size)) 205 qs->tail = 0; 206 } 207 208 dst = &qs->elements[qs->head * qs->map.value_size]; 209 memcpy(dst, value, qs->map.value_size); 210 211 if (unlikely(++qs->head >= qs->size)) 212 qs->head = 0; 213 214 out: 215 raw_spin_unlock_irqrestore(&qs->lock, irq_flags); 216 return err; 217 } 218 219 /* Called from syscall or from eBPF program */ 220 static void *queue_stack_map_lookup_elem(struct bpf_map *map, void *key) 221 { 222 return NULL; 223 } 224 225 /* Called from syscall or from eBPF program */ 226 static long queue_stack_map_update_elem(struct bpf_map *map, void *key, 227 void *value, u64 flags) 228 { 229 return -EINVAL; 230 } 231 232 /* Called from syscall or from eBPF program */ 233 static long queue_stack_map_delete_elem(struct bpf_map *map, void *key) 234 { 235 return -EINVAL; 236 } 237 238 /* Called from syscall */ 239 static int queue_stack_map_get_next_key(struct bpf_map *map, void *key, 240 void *next_key) 241 { 242 return -EINVAL; 243 } 244 245 static u64 queue_stack_map_mem_usage(const struct bpf_map *map) 246 { 247 u64 usage = sizeof(struct bpf_queue_stack); 248 249 usage += ((u64)map->max_entries + 1) * map->value_size; 250 return usage; 251 } 252 253 BTF_ID_LIST_SINGLE(queue_map_btf_ids, struct, bpf_queue_stack) 254 const struct bpf_map_ops queue_map_ops = { 255 .map_meta_equal = bpf_map_meta_equal, 256 .map_alloc_check = queue_stack_map_alloc_check, 257 .map_alloc = queue_stack_map_alloc, 258 .map_free = queue_stack_map_free, 259 .map_lookup_elem = queue_stack_map_lookup_elem, 260 .map_update_elem = queue_stack_map_update_elem, 261 .map_delete_elem = queue_stack_map_delete_elem, 262 .map_push_elem = queue_stack_map_push_elem, 263 .map_pop_elem = queue_map_pop_elem, 264 .map_peek_elem = queue_map_peek_elem, 265 .map_get_next_key = queue_stack_map_get_next_key, 266 .map_mem_usage = queue_stack_map_mem_usage, 267 .map_btf_id = &queue_map_btf_ids[0], 268 }; 269 270 const struct bpf_map_ops stack_map_ops = { 271 .map_meta_equal = bpf_map_meta_equal, 272 .map_alloc_check = queue_stack_map_alloc_check, 273 .map_alloc = queue_stack_map_alloc, 274 .map_free = queue_stack_map_free, 275 .map_lookup_elem = queue_stack_map_lookup_elem, 276 .map_update_elem = queue_stack_map_update_elem, 277 .map_delete_elem = queue_stack_map_delete_elem, 278 .map_push_elem = queue_stack_map_push_elem, 279 .map_pop_elem = stack_map_pop_elem, 280 .map_peek_elem = stack_map_peek_elem, 281 .map_get_next_key = queue_stack_map_get_next_key, 282 .map_mem_usage = queue_stack_map_mem_usage, 283 .map_btf_id = &queue_map_btf_ids[0], 284 }; 285