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 #include <asm/rqspinlock.h> 13 14 #define QUEUE_STACK_CREATE_FLAG_MASK \ 15 (BPF_F_NUMA_NODE | BPF_F_ACCESS_MASK) 16 17 struct bpf_queue_stack { 18 struct bpf_map map; 19 rqspinlock_t lock; 20 u32 head, tail; 21 u32 size; /* max_entries + 1 */ 22 23 char elements[] __aligned(8); 24 }; 25 26 static struct bpf_queue_stack *bpf_queue_stack(struct bpf_map *map) 27 { 28 return container_of(map, struct bpf_queue_stack, map); 29 } 30 31 static bool queue_stack_map_is_empty(struct bpf_queue_stack *qs) 32 { 33 return qs->head == qs->tail; 34 } 35 36 static bool queue_stack_map_is_full(struct bpf_queue_stack *qs) 37 { 38 u32 head = qs->head + 1; 39 40 if (unlikely(head >= qs->size)) 41 head = 0; 42 43 return head == qs->tail; 44 } 45 46 /* Called from syscall */ 47 static int queue_stack_map_alloc_check(union bpf_attr *attr) 48 { 49 /* check sanity of attributes */ 50 if (attr->max_entries == 0 || attr->key_size != 0 || 51 attr->value_size == 0 || 52 attr->map_flags & ~QUEUE_STACK_CREATE_FLAG_MASK || 53 !bpf_map_flags_access_ok(attr->map_flags)) 54 return -EINVAL; 55 56 if (attr->value_size > KMALLOC_MAX_SIZE) 57 /* if value_size is bigger, the user space won't be able to 58 * access the elements. 59 */ 60 return -E2BIG; 61 62 return 0; 63 } 64 65 static struct bpf_map *queue_stack_map_alloc(union bpf_attr *attr) 66 { 67 int numa_node = bpf_map_attr_numa_node(attr); 68 struct bpf_queue_stack *qs; 69 u64 size, queue_size; 70 71 size = (u64) attr->max_entries + 1; 72 queue_size = sizeof(*qs) + size * attr->value_size; 73 74 qs = bpf_map_area_alloc(queue_size, numa_node); 75 if (!qs) 76 return ERR_PTR(-ENOMEM); 77 78 bpf_map_init_from_attr(&qs->map, attr); 79 80 qs->size = size; 81 82 raw_res_spin_lock_init(&qs->lock); 83 84 return &qs->map; 85 } 86 87 /* Called when map->refcnt goes to zero, either from workqueue or from syscall */ 88 static void queue_stack_map_free(struct bpf_map *map) 89 { 90 struct bpf_queue_stack *qs = bpf_queue_stack(map); 91 92 bpf_map_area_free(qs); 93 } 94 95 static long __queue_map_get(struct bpf_map *map, void *value, bool delete) 96 { 97 struct bpf_queue_stack *qs = bpf_queue_stack(map); 98 unsigned long flags; 99 int err = 0; 100 void *ptr; 101 102 if (raw_res_spin_lock_irqsave(&qs->lock, flags)) 103 return -EBUSY; 104 105 if (queue_stack_map_is_empty(qs)) { 106 memset(value, 0, qs->map.value_size); 107 err = -ENOENT; 108 goto out; 109 } 110 111 ptr = &qs->elements[qs->tail * qs->map.value_size]; 112 memcpy(value, ptr, qs->map.value_size); 113 114 if (delete) { 115 if (unlikely(++qs->tail >= qs->size)) 116 qs->tail = 0; 117 } 118 119 out: 120 raw_res_spin_unlock_irqrestore(&qs->lock, flags); 121 return err; 122 } 123 124 125 static long __stack_map_get(struct bpf_map *map, void *value, bool delete) 126 { 127 struct bpf_queue_stack *qs = bpf_queue_stack(map); 128 unsigned long flags; 129 int err = 0; 130 void *ptr; 131 u32 index; 132 133 if (raw_res_spin_lock_irqsave(&qs->lock, flags)) 134 return -EBUSY; 135 136 if (queue_stack_map_is_empty(qs)) { 137 memset(value, 0, qs->map.value_size); 138 err = -ENOENT; 139 goto out; 140 } 141 142 index = qs->head - 1; 143 if (unlikely(index >= qs->size)) 144 index = qs->size - 1; 145 146 ptr = &qs->elements[index * qs->map.value_size]; 147 memcpy(value, ptr, qs->map.value_size); 148 149 if (delete) 150 qs->head = index; 151 152 out: 153 raw_res_spin_unlock_irqrestore(&qs->lock, flags); 154 return err; 155 } 156 157 /* Called from syscall or from eBPF program */ 158 static long queue_map_peek_elem(struct bpf_map *map, void *value) 159 { 160 return __queue_map_get(map, value, false); 161 } 162 163 /* Called from syscall or from eBPF program */ 164 static long stack_map_peek_elem(struct bpf_map *map, void *value) 165 { 166 return __stack_map_get(map, value, false); 167 } 168 169 /* Called from syscall or from eBPF program */ 170 static long queue_map_pop_elem(struct bpf_map *map, void *value) 171 { 172 return __queue_map_get(map, value, true); 173 } 174 175 /* Called from syscall or from eBPF program */ 176 static long stack_map_pop_elem(struct bpf_map *map, void *value) 177 { 178 return __stack_map_get(map, value, true); 179 } 180 181 /* Called from syscall or from eBPF program */ 182 static long queue_stack_map_push_elem(struct bpf_map *map, void *value, 183 u64 flags) 184 { 185 struct bpf_queue_stack *qs = bpf_queue_stack(map); 186 unsigned long irq_flags; 187 int err = 0; 188 void *dst; 189 190 /* BPF_EXIST is used to force making room for a new element in case the 191 * map is full 192 */ 193 bool replace = (flags & BPF_EXIST); 194 195 /* Check supported flags for queue and stack maps */ 196 if (flags & BPF_NOEXIST || flags > BPF_EXIST) 197 return -EINVAL; 198 199 if (raw_res_spin_lock_irqsave(&qs->lock, irq_flags)) 200 return -EBUSY; 201 202 if (queue_stack_map_is_full(qs)) { 203 if (!replace) { 204 err = -E2BIG; 205 goto out; 206 } 207 /* advance tail pointer to overwrite oldest element */ 208 if (unlikely(++qs->tail >= qs->size)) 209 qs->tail = 0; 210 } 211 212 dst = &qs->elements[qs->head * qs->map.value_size]; 213 memcpy(dst, value, qs->map.value_size); 214 215 if (unlikely(++qs->head >= qs->size)) 216 qs->head = 0; 217 218 out: 219 raw_res_spin_unlock_irqrestore(&qs->lock, irq_flags); 220 return err; 221 } 222 223 /* Called from syscall or from eBPF program */ 224 static void *queue_stack_map_lookup_elem(struct bpf_map *map, void *key) 225 { 226 return NULL; 227 } 228 229 /* Called from syscall or from eBPF program */ 230 static long queue_stack_map_update_elem(struct bpf_map *map, void *key, 231 void *value, u64 flags) 232 { 233 return -EINVAL; 234 } 235 236 /* Called from syscall or from eBPF program */ 237 static long queue_stack_map_delete_elem(struct bpf_map *map, void *key) 238 { 239 return -EINVAL; 240 } 241 242 /* Called from syscall */ 243 static int queue_stack_map_get_next_key(struct bpf_map *map, void *key, 244 void *next_key) 245 { 246 return -EINVAL; 247 } 248 249 static u64 queue_stack_map_mem_usage(const struct bpf_map *map) 250 { 251 u64 usage = sizeof(struct bpf_queue_stack); 252 253 usage += ((u64)map->max_entries + 1) * map->value_size; 254 return usage; 255 } 256 257 BTF_ID_LIST_SINGLE(queue_map_btf_ids, struct, bpf_queue_stack) 258 const struct bpf_map_ops queue_map_ops = { 259 .map_meta_equal = bpf_map_meta_equal, 260 .map_alloc_check = queue_stack_map_alloc_check, 261 .map_alloc = queue_stack_map_alloc, 262 .map_free = queue_stack_map_free, 263 .map_lookup_elem = queue_stack_map_lookup_elem, 264 .map_update_elem = queue_stack_map_update_elem, 265 .map_delete_elem = queue_stack_map_delete_elem, 266 .map_push_elem = queue_stack_map_push_elem, 267 .map_pop_elem = queue_map_pop_elem, 268 .map_peek_elem = queue_map_peek_elem, 269 .map_get_next_key = queue_stack_map_get_next_key, 270 .map_mem_usage = queue_stack_map_mem_usage, 271 .map_btf_id = &queue_map_btf_ids[0], 272 }; 273 274 const struct bpf_map_ops stack_map_ops = { 275 .map_meta_equal = bpf_map_meta_equal, 276 .map_alloc_check = queue_stack_map_alloc_check, 277 .map_alloc = queue_stack_map_alloc, 278 .map_free = queue_stack_map_free, 279 .map_lookup_elem = queue_stack_map_lookup_elem, 280 .map_update_elem = queue_stack_map_update_elem, 281 .map_delete_elem = queue_stack_map_delete_elem, 282 .map_push_elem = queue_stack_map_push_elem, 283 .map_pop_elem = stack_map_pop_elem, 284 .map_peek_elem = stack_map_peek_elem, 285 .map_get_next_key = queue_stack_map_get_next_key, 286 .map_mem_usage = queue_stack_map_mem_usage, 287 .map_btf_id = &queue_map_btf_ids[0], 288 }; 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