projects/linux·blob f24767ca · refs

284 lines · 6.8 KiB

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
16struct 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
25static struct bpf_queue_stack *bpf_queue_stack(struct bpf_map *map)
26{
27 return container_of(map, struct bpf_queue_stack, map);
28}
29
30static bool queue_stack_map_is_empty(struct bpf_queue_stack *qs)
31{
32 return qs->head == qs->tail;
33}
34
35static 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 */
46static 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
64static 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 */
87static 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
94static 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
117out:
118 raw_spin_unlock_irqrestore(&qs->lock, flags);
119 return err;
120}
121
122
123static 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
149out:
150 raw_spin_unlock_irqrestore(&qs->lock, flags);
151 return err;
152}
153
154/* Called from syscall or from eBPF program */
155static 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 */
161static 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 */
167static 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 */
173static 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 */
179static 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
214out:
215 raw_spin_unlock_irqrestore(&qs->lock, irq_flags);
216 return err;
217}
218
219/* Called from syscall or from eBPF program */
220static 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 */
226static 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 */
233static long queue_stack_map_delete_elem(struct bpf_map *map, void *key)
234{
235 return -EINVAL;
236}
237
238/* Called from syscall */
239static int queue_stack_map_get_next_key(struct bpf_map *map, void *key,
240 void *next_key)
241{
242 return -EINVAL;
243}
244
245static 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
253BTF_ID_LIST_SINGLE(queue_map_btf_ids, struct, bpf_queue_stack)
254const 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
270const 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};