1 // SPDX-License-Identifier: GPL-2.0
3 * queue_stack_maps.c: BPF queue and stack maps
5 * Copyright (c) 2018 Politecnico di Torino
8 #include <linux/list.h>
9 #include <linux/slab.h>
10 #include <linux/capability.h>
11 #include <linux/btf_ids.h>
12 #include "percpu_freelist.h"
14 #define QUEUE_STACK_CREATE_FLAG_MASK \
15 (BPF_F_NUMA_NODE | BPF_F_ACCESS_MASK)
17 struct bpf_queue_stack {
21 u32 size; /* max_entries + 1 */
23 char elements[] __aligned(8);
26 static struct bpf_queue_stack *bpf_queue_stack(struct bpf_map *map)
28 return container_of(map, struct bpf_queue_stack, map);
31 static bool queue_stack_map_is_empty(struct bpf_queue_stack *qs)
33 return qs->head == qs->tail;
36 static bool queue_stack_map_is_full(struct bpf_queue_stack *qs)
38 u32 head = qs->head + 1;
40 if (unlikely(head >= qs->size))
43 return head == qs->tail;
46 /* Called from syscall */
47 static int queue_stack_map_alloc_check(union bpf_attr *attr)
52 /* check sanity of attributes */
53 if (attr->max_entries == 0 || attr->key_size != 0 ||
54 attr->value_size == 0 ||
55 attr->map_flags & ~QUEUE_STACK_CREATE_FLAG_MASK ||
56 !bpf_map_flags_access_ok(attr->map_flags))
59 if (attr->value_size > KMALLOC_MAX_SIZE)
60 /* if value_size is bigger, the user space won't be able to
61 * access the elements.
68 static struct bpf_map *queue_stack_map_alloc(union bpf_attr *attr)
70 int numa_node = bpf_map_attr_numa_node(attr);
71 struct bpf_queue_stack *qs;
74 size = (u64) attr->max_entries + 1;
75 queue_size = sizeof(*qs) + size * attr->value_size;
77 qs = bpf_map_area_alloc(queue_size, numa_node);
79 return ERR_PTR(-ENOMEM);
81 memset(qs, 0, sizeof(*qs));
83 bpf_map_init_from_attr(&qs->map, attr);
87 raw_spin_lock_init(&qs->lock);
92 /* Called when map->refcnt goes to zero, either from workqueue or from syscall */
93 static void queue_stack_map_free(struct bpf_map *map)
95 struct bpf_queue_stack *qs = bpf_queue_stack(map);
97 bpf_map_area_free(qs);
100 static int __queue_map_get(struct bpf_map *map, void *value, bool delete)
102 struct bpf_queue_stack *qs = bpf_queue_stack(map);
107 raw_spin_lock_irqsave(&qs->lock, flags);
109 if (queue_stack_map_is_empty(qs)) {
110 memset(value, 0, qs->map.value_size);
115 ptr = &qs->elements[qs->tail * qs->map.value_size];
116 memcpy(value, ptr, qs->map.value_size);
119 if (unlikely(++qs->tail >= qs->size))
124 raw_spin_unlock_irqrestore(&qs->lock, flags);
129 static int __stack_map_get(struct bpf_map *map, void *value, bool delete)
131 struct bpf_queue_stack *qs = bpf_queue_stack(map);
137 raw_spin_lock_irqsave(&qs->lock, flags);
139 if (queue_stack_map_is_empty(qs)) {
140 memset(value, 0, qs->map.value_size);
145 index = qs->head - 1;
146 if (unlikely(index >= qs->size))
147 index = qs->size - 1;
149 ptr = &qs->elements[index * qs->map.value_size];
150 memcpy(value, ptr, qs->map.value_size);
156 raw_spin_unlock_irqrestore(&qs->lock, flags);
160 /* Called from syscall or from eBPF program */
161 static int queue_map_peek_elem(struct bpf_map *map, void *value)
163 return __queue_map_get(map, value, false);
166 /* Called from syscall or from eBPF program */
167 static int stack_map_peek_elem(struct bpf_map *map, void *value)
169 return __stack_map_get(map, value, false);
172 /* Called from syscall or from eBPF program */
173 static int queue_map_pop_elem(struct bpf_map *map, void *value)
175 return __queue_map_get(map, value, true);
178 /* Called from syscall or from eBPF program */
179 static int stack_map_pop_elem(struct bpf_map *map, void *value)
181 return __stack_map_get(map, value, true);
184 /* Called from syscall or from eBPF program */
185 static int queue_stack_map_push_elem(struct bpf_map *map, void *value,
188 struct bpf_queue_stack *qs = bpf_queue_stack(map);
189 unsigned long irq_flags;
193 /* BPF_EXIST is used to force making room for a new element in case the
196 bool replace = (flags & BPF_EXIST);
198 /* Check supported flags for queue and stack maps */
199 if (flags & BPF_NOEXIST || flags > BPF_EXIST)
202 raw_spin_lock_irqsave(&qs->lock, irq_flags);
204 if (queue_stack_map_is_full(qs)) {
209 /* advance tail pointer to overwrite oldest element */
210 if (unlikely(++qs->tail >= qs->size))
214 dst = &qs->elements[qs->head * qs->map.value_size];
215 memcpy(dst, value, qs->map.value_size);
217 if (unlikely(++qs->head >= qs->size))
221 raw_spin_unlock_irqrestore(&qs->lock, irq_flags);
225 /* Called from syscall or from eBPF program */
226 static void *queue_stack_map_lookup_elem(struct bpf_map *map, void *key)
231 /* Called from syscall or from eBPF program */
232 static int queue_stack_map_update_elem(struct bpf_map *map, void *key,
233 void *value, u64 flags)
238 /* Called from syscall or from eBPF program */
239 static int queue_stack_map_delete_elem(struct bpf_map *map, void *key)
244 /* Called from syscall */
245 static int queue_stack_map_get_next_key(struct bpf_map *map, void *key,
251 BTF_ID_LIST_SINGLE(queue_map_btf_ids, struct, bpf_queue_stack)
252 const struct bpf_map_ops queue_map_ops = {
253 .map_meta_equal = bpf_map_meta_equal,
254 .map_alloc_check = queue_stack_map_alloc_check,
255 .map_alloc = queue_stack_map_alloc,
256 .map_free = queue_stack_map_free,
257 .map_lookup_elem = queue_stack_map_lookup_elem,
258 .map_update_elem = queue_stack_map_update_elem,
259 .map_delete_elem = queue_stack_map_delete_elem,
260 .map_push_elem = queue_stack_map_push_elem,
261 .map_pop_elem = queue_map_pop_elem,
262 .map_peek_elem = queue_map_peek_elem,
263 .map_get_next_key = queue_stack_map_get_next_key,
264 .map_btf_id = &queue_map_btf_ids[0],
267 const struct bpf_map_ops stack_map_ops = {
268 .map_meta_equal = bpf_map_meta_equal,
269 .map_alloc_check = queue_stack_map_alloc_check,
270 .map_alloc = queue_stack_map_alloc,
271 .map_free = queue_stack_map_free,
272 .map_lookup_elem = queue_stack_map_lookup_elem,
273 .map_update_elem = queue_stack_map_update_elem,
274 .map_delete_elem = queue_stack_map_delete_elem,
275 .map_push_elem = queue_stack_map_push_elem,
276 .map_pop_elem = stack_map_pop_elem,
277 .map_peek_elem = stack_map_peek_elem,
278 .map_get_next_key = queue_stack_map_get_next_key,
279 .map_btf_id = &queue_map_btf_ids[0],