queue_stack_maps.c

  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
 17struct 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
 26static struct bpf_queue_stack *bpf_queue_stack(struct bpf_map *map)
 27{
 28	return container_of(map, struct bpf_queue_stack, map);
 29}
 30
 31static bool queue_stack_map_is_empty(struct bpf_queue_stack *qs)
 32{
 33	return qs->head == qs->tail;
 34}
 35
 36static 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 */
 47static 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
 65static 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 */
 88static 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
 95static 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
119out:
120	raw_res_spin_unlock_irqrestore(&qs->lock, flags);
121	return err;
122}
123
124
125static 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
152out:
153	raw_res_spin_unlock_irqrestore(&qs->lock, flags);
154	return err;
155}
156
157/* Called from syscall or from eBPF program */
158static 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 */
164static 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 */
170static 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 */
176static 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 */
182static 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
218out:
219	raw_res_spin_unlock_irqrestore(&qs->lock, irq_flags);
220	return err;
221}
222
223/* Called from syscall or from eBPF program */
224static 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 */
230static 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 */
237static long queue_stack_map_delete_elem(struct bpf_map *map, void *key)
238{
239	return -EINVAL;
240}
241
242/* Called from syscall */
243static int queue_stack_map_get_next_key(struct bpf_map *map, void *key,
244					void *next_key)
245{
246	return -EINVAL;
247}
248
249static 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
257BTF_ID_LIST_SINGLE(queue_map_btf_ids, struct, bpf_queue_stack)
258const 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
274const 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};