xref: /openbmc/linux/kernel/bpf/hashtab.c (revision e639c869)
1 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
2  * Copyright (c) 2016 Facebook
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of version 2 of the GNU General Public
6  * License as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful, but
9  * WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11  * General Public License for more details.
12  */
13 #include <linux/bpf.h>
14 #include <linux/jhash.h>
15 #include <linux/filter.h>
16 #include <linux/rculist_nulls.h>
17 #include "percpu_freelist.h"
18 #include "bpf_lru_list.h"
19 #include "map_in_map.h"
20 
21 #define HTAB_CREATE_FLAG_MASK						\
22 	(BPF_F_NO_PREALLOC | BPF_F_NO_COMMON_LRU | BPF_F_NUMA_NODE |	\
23 	 BPF_F_RDONLY | BPF_F_WRONLY)
24 
25 struct bucket {
26 	struct hlist_nulls_head head;
27 	raw_spinlock_t lock;
28 };
29 
30 struct bpf_htab {
31 	struct bpf_map map;
32 	struct bucket *buckets;
33 	void *elems;
34 	union {
35 		struct pcpu_freelist freelist;
36 		struct bpf_lru lru;
37 	};
38 	struct htab_elem *__percpu *extra_elems;
39 	atomic_t count;	/* number of elements in this hashtable */
40 	u32 n_buckets;	/* number of hash buckets */
41 	u32 elem_size;	/* size of each element in bytes */
42 };
43 
44 /* each htab element is struct htab_elem + key + value */
45 struct htab_elem {
46 	union {
47 		struct hlist_nulls_node hash_node;
48 		struct {
49 			void *padding;
50 			union {
51 				struct bpf_htab *htab;
52 				struct pcpu_freelist_node fnode;
53 			};
54 		};
55 	};
56 	union {
57 		struct rcu_head rcu;
58 		struct bpf_lru_node lru_node;
59 	};
60 	u32 hash;
61 	char key[0] __aligned(8);
62 };
63 
64 static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node);
65 
66 static bool htab_is_lru(const struct bpf_htab *htab)
67 {
68 	return htab->map.map_type == BPF_MAP_TYPE_LRU_HASH ||
69 		htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;
70 }
71 
72 static bool htab_is_percpu(const struct bpf_htab *htab)
73 {
74 	return htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH ||
75 		htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;
76 }
77 
78 static bool htab_is_prealloc(const struct bpf_htab *htab)
79 {
80 	return !(htab->map.map_flags & BPF_F_NO_PREALLOC);
81 }
82 
83 static inline void htab_elem_set_ptr(struct htab_elem *l, u32 key_size,
84 				     void __percpu *pptr)
85 {
86 	*(void __percpu **)(l->key + key_size) = pptr;
87 }
88 
89 static inline void __percpu *htab_elem_get_ptr(struct htab_elem *l, u32 key_size)
90 {
91 	return *(void __percpu **)(l->key + key_size);
92 }
93 
94 static void *fd_htab_map_get_ptr(const struct bpf_map *map, struct htab_elem *l)
95 {
96 	return *(void **)(l->key + roundup(map->key_size, 8));
97 }
98 
99 static struct htab_elem *get_htab_elem(struct bpf_htab *htab, int i)
100 {
101 	return (struct htab_elem *) (htab->elems + i * htab->elem_size);
102 }
103 
104 static void htab_free_elems(struct bpf_htab *htab)
105 {
106 	int i;
107 
108 	if (!htab_is_percpu(htab))
109 		goto free_elems;
110 
111 	for (i = 0; i < htab->map.max_entries; i++) {
112 		void __percpu *pptr;
113 
114 		pptr = htab_elem_get_ptr(get_htab_elem(htab, i),
115 					 htab->map.key_size);
116 		free_percpu(pptr);
117 	}
118 free_elems:
119 	bpf_map_area_free(htab->elems);
120 }
121 
122 static struct htab_elem *prealloc_lru_pop(struct bpf_htab *htab, void *key,
123 					  u32 hash)
124 {
125 	struct bpf_lru_node *node = bpf_lru_pop_free(&htab->lru, hash);
126 	struct htab_elem *l;
127 
128 	if (node) {
129 		l = container_of(node, struct htab_elem, lru_node);
130 		memcpy(l->key, key, htab->map.key_size);
131 		return l;
132 	}
133 
134 	return NULL;
135 }
136 
137 static int prealloc_init(struct bpf_htab *htab)
138 {
139 	u32 num_entries = htab->map.max_entries;
140 	int err = -ENOMEM, i;
141 
142 	if (!htab_is_percpu(htab) && !htab_is_lru(htab))
143 		num_entries += num_possible_cpus();
144 
145 	htab->elems = bpf_map_area_alloc(htab->elem_size * num_entries,
146 					 htab->map.numa_node);
147 	if (!htab->elems)
148 		return -ENOMEM;
149 
150 	if (!htab_is_percpu(htab))
151 		goto skip_percpu_elems;
152 
153 	for (i = 0; i < num_entries; i++) {
154 		u32 size = round_up(htab->map.value_size, 8);
155 		void __percpu *pptr;
156 
157 		pptr = __alloc_percpu_gfp(size, 8, GFP_USER | __GFP_NOWARN);
158 		if (!pptr)
159 			goto free_elems;
160 		htab_elem_set_ptr(get_htab_elem(htab, i), htab->map.key_size,
161 				  pptr);
162 	}
163 
164 skip_percpu_elems:
165 	if (htab_is_lru(htab))
166 		err = bpf_lru_init(&htab->lru,
167 				   htab->map.map_flags & BPF_F_NO_COMMON_LRU,
168 				   offsetof(struct htab_elem, hash) -
169 				   offsetof(struct htab_elem, lru_node),
170 				   htab_lru_map_delete_node,
171 				   htab);
172 	else
173 		err = pcpu_freelist_init(&htab->freelist);
174 
175 	if (err)
176 		goto free_elems;
177 
178 	if (htab_is_lru(htab))
179 		bpf_lru_populate(&htab->lru, htab->elems,
180 				 offsetof(struct htab_elem, lru_node),
181 				 htab->elem_size, num_entries);
182 	else
183 		pcpu_freelist_populate(&htab->freelist,
184 				       htab->elems + offsetof(struct htab_elem, fnode),
185 				       htab->elem_size, num_entries);
186 
187 	return 0;
188 
189 free_elems:
190 	htab_free_elems(htab);
191 	return err;
192 }
193 
194 static void prealloc_destroy(struct bpf_htab *htab)
195 {
196 	htab_free_elems(htab);
197 
198 	if (htab_is_lru(htab))
199 		bpf_lru_destroy(&htab->lru);
200 	else
201 		pcpu_freelist_destroy(&htab->freelist);
202 }
203 
204 static int alloc_extra_elems(struct bpf_htab *htab)
205 {
206 	struct htab_elem *__percpu *pptr, *l_new;
207 	struct pcpu_freelist_node *l;
208 	int cpu;
209 
210 	pptr = __alloc_percpu_gfp(sizeof(struct htab_elem *), 8,
211 				  GFP_USER | __GFP_NOWARN);
212 	if (!pptr)
213 		return -ENOMEM;
214 
215 	for_each_possible_cpu(cpu) {
216 		l = pcpu_freelist_pop(&htab->freelist);
217 		/* pop will succeed, since prealloc_init()
218 		 * preallocated extra num_possible_cpus elements
219 		 */
220 		l_new = container_of(l, struct htab_elem, fnode);
221 		*per_cpu_ptr(pptr, cpu) = l_new;
222 	}
223 	htab->extra_elems = pptr;
224 	return 0;
225 }
226 
227 /* Called from syscall */
228 static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
229 {
230 	bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
231 		       attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
232 	bool lru = (attr->map_type == BPF_MAP_TYPE_LRU_HASH ||
233 		    attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
234 	/* percpu_lru means each cpu has its own LRU list.
235 	 * it is different from BPF_MAP_TYPE_PERCPU_HASH where
236 	 * the map's value itself is percpu.  percpu_lru has
237 	 * nothing to do with the map's value.
238 	 */
239 	bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU);
240 	bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC);
241 	int numa_node = bpf_map_attr_numa_node(attr);
242 	struct bpf_htab *htab;
243 	int err, i;
244 	u64 cost;
245 
246 	BUILD_BUG_ON(offsetof(struct htab_elem, htab) !=
247 		     offsetof(struct htab_elem, hash_node.pprev));
248 	BUILD_BUG_ON(offsetof(struct htab_elem, fnode.next) !=
249 		     offsetof(struct htab_elem, hash_node.pprev));
250 
251 	if (lru && !capable(CAP_SYS_ADMIN))
252 		/* LRU implementation is much complicated than other
253 		 * maps.  Hence, limit to CAP_SYS_ADMIN for now.
254 		 */
255 		return ERR_PTR(-EPERM);
256 
257 	if (attr->map_flags & ~HTAB_CREATE_FLAG_MASK)
258 		/* reserved bits should not be used */
259 		return ERR_PTR(-EINVAL);
260 
261 	if (!lru && percpu_lru)
262 		return ERR_PTR(-EINVAL);
263 
264 	if (lru && !prealloc)
265 		return ERR_PTR(-ENOTSUPP);
266 
267 	if (numa_node != NUMA_NO_NODE && (percpu || percpu_lru))
268 		return ERR_PTR(-EINVAL);
269 
270 	htab = kzalloc(sizeof(*htab), GFP_USER);
271 	if (!htab)
272 		return ERR_PTR(-ENOMEM);
273 
274 	/* mandatory map attributes */
275 	htab->map.map_type = attr->map_type;
276 	htab->map.key_size = attr->key_size;
277 	htab->map.value_size = attr->value_size;
278 	htab->map.max_entries = attr->max_entries;
279 	htab->map.map_flags = attr->map_flags;
280 	htab->map.numa_node = numa_node;
281 
282 	/* check sanity of attributes.
283 	 * value_size == 0 may be allowed in the future to use map as a set
284 	 */
285 	err = -EINVAL;
286 	if (htab->map.max_entries == 0 || htab->map.key_size == 0 ||
287 	    htab->map.value_size == 0)
288 		goto free_htab;
289 
290 	if (percpu_lru) {
291 		/* ensure each CPU's lru list has >=1 elements.
292 		 * since we are at it, make each lru list has the same
293 		 * number of elements.
294 		 */
295 		htab->map.max_entries = roundup(attr->max_entries,
296 						num_possible_cpus());
297 		if (htab->map.max_entries < attr->max_entries)
298 			htab->map.max_entries = rounddown(attr->max_entries,
299 							  num_possible_cpus());
300 	}
301 
302 	/* hash table size must be power of 2 */
303 	htab->n_buckets = roundup_pow_of_two(htab->map.max_entries);
304 
305 	err = -E2BIG;
306 	if (htab->map.key_size > MAX_BPF_STACK)
307 		/* eBPF programs initialize keys on stack, so they cannot be
308 		 * larger than max stack size
309 		 */
310 		goto free_htab;
311 
312 	if (htab->map.value_size >= KMALLOC_MAX_SIZE -
313 	    MAX_BPF_STACK - sizeof(struct htab_elem))
314 		/* if value_size is bigger, the user space won't be able to
315 		 * access the elements via bpf syscall. This check also makes
316 		 * sure that the elem_size doesn't overflow and it's
317 		 * kmalloc-able later in htab_map_update_elem()
318 		 */
319 		goto free_htab;
320 
321 	htab->elem_size = sizeof(struct htab_elem) +
322 			  round_up(htab->map.key_size, 8);
323 	if (percpu)
324 		htab->elem_size += sizeof(void *);
325 	else
326 		htab->elem_size += round_up(htab->map.value_size, 8);
327 
328 	/* prevent zero size kmalloc and check for u32 overflow */
329 	if (htab->n_buckets == 0 ||
330 	    htab->n_buckets > U32_MAX / sizeof(struct bucket))
331 		goto free_htab;
332 
333 	cost = (u64) htab->n_buckets * sizeof(struct bucket) +
334 	       (u64) htab->elem_size * htab->map.max_entries;
335 
336 	if (percpu)
337 		cost += (u64) round_up(htab->map.value_size, 8) *
338 			num_possible_cpus() * htab->map.max_entries;
339 	else
340 	       cost += (u64) htab->elem_size * num_possible_cpus();
341 
342 	if (cost >= U32_MAX - PAGE_SIZE)
343 		/* make sure page count doesn't overflow */
344 		goto free_htab;
345 
346 	htab->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT;
347 
348 	/* if map size is larger than memlock limit, reject it early */
349 	err = bpf_map_precharge_memlock(htab->map.pages);
350 	if (err)
351 		goto free_htab;
352 
353 	err = -ENOMEM;
354 	htab->buckets = bpf_map_area_alloc(htab->n_buckets *
355 					   sizeof(struct bucket),
356 					   htab->map.numa_node);
357 	if (!htab->buckets)
358 		goto free_htab;
359 
360 	for (i = 0; i < htab->n_buckets; i++) {
361 		INIT_HLIST_NULLS_HEAD(&htab->buckets[i].head, i);
362 		raw_spin_lock_init(&htab->buckets[i].lock);
363 	}
364 
365 	if (prealloc) {
366 		err = prealloc_init(htab);
367 		if (err)
368 			goto free_buckets;
369 
370 		if (!percpu && !lru) {
371 			/* lru itself can remove the least used element, so
372 			 * there is no need for an extra elem during map_update.
373 			 */
374 			err = alloc_extra_elems(htab);
375 			if (err)
376 				goto free_prealloc;
377 		}
378 	}
379 
380 	return &htab->map;
381 
382 free_prealloc:
383 	prealloc_destroy(htab);
384 free_buckets:
385 	bpf_map_area_free(htab->buckets);
386 free_htab:
387 	kfree(htab);
388 	return ERR_PTR(err);
389 }
390 
391 static inline u32 htab_map_hash(const void *key, u32 key_len)
392 {
393 	return jhash(key, key_len, 0);
394 }
395 
396 static inline struct bucket *__select_bucket(struct bpf_htab *htab, u32 hash)
397 {
398 	return &htab->buckets[hash & (htab->n_buckets - 1)];
399 }
400 
401 static inline struct hlist_nulls_head *select_bucket(struct bpf_htab *htab, u32 hash)
402 {
403 	return &__select_bucket(htab, hash)->head;
404 }
405 
406 /* this lookup function can only be called with bucket lock taken */
407 static struct htab_elem *lookup_elem_raw(struct hlist_nulls_head *head, u32 hash,
408 					 void *key, u32 key_size)
409 {
410 	struct hlist_nulls_node *n;
411 	struct htab_elem *l;
412 
413 	hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
414 		if (l->hash == hash && !memcmp(&l->key, key, key_size))
415 			return l;
416 
417 	return NULL;
418 }
419 
420 /* can be called without bucket lock. it will repeat the loop in
421  * the unlikely event when elements moved from one bucket into another
422  * while link list is being walked
423  */
424 static struct htab_elem *lookup_nulls_elem_raw(struct hlist_nulls_head *head,
425 					       u32 hash, void *key,
426 					       u32 key_size, u32 n_buckets)
427 {
428 	struct hlist_nulls_node *n;
429 	struct htab_elem *l;
430 
431 again:
432 	hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
433 		if (l->hash == hash && !memcmp(&l->key, key, key_size))
434 			return l;
435 
436 	if (unlikely(get_nulls_value(n) != (hash & (n_buckets - 1))))
437 		goto again;
438 
439 	return NULL;
440 }
441 
442 /* Called from syscall or from eBPF program directly, so
443  * arguments have to match bpf_map_lookup_elem() exactly.
444  * The return value is adjusted by BPF instructions
445  * in htab_map_gen_lookup().
446  */
447 static void *__htab_map_lookup_elem(struct bpf_map *map, void *key)
448 {
449 	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
450 	struct hlist_nulls_head *head;
451 	struct htab_elem *l;
452 	u32 hash, key_size;
453 
454 	/* Must be called with rcu_read_lock. */
455 	WARN_ON_ONCE(!rcu_read_lock_held());
456 
457 	key_size = map->key_size;
458 
459 	hash = htab_map_hash(key, key_size);
460 
461 	head = select_bucket(htab, hash);
462 
463 	l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);
464 
465 	return l;
466 }
467 
468 static void *htab_map_lookup_elem(struct bpf_map *map, void *key)
469 {
470 	struct htab_elem *l = __htab_map_lookup_elem(map, key);
471 
472 	if (l)
473 		return l->key + round_up(map->key_size, 8);
474 
475 	return NULL;
476 }
477 
478 /* inline bpf_map_lookup_elem() call.
479  * Instead of:
480  * bpf_prog
481  *   bpf_map_lookup_elem
482  *     map->ops->map_lookup_elem
483  *       htab_map_lookup_elem
484  *         __htab_map_lookup_elem
485  * do:
486  * bpf_prog
487  *   __htab_map_lookup_elem
488  */
489 static u32 htab_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
490 {
491 	struct bpf_insn *insn = insn_buf;
492 	const int ret = BPF_REG_0;
493 
494 	*insn++ = BPF_EMIT_CALL((u64 (*)(u64, u64, u64, u64, u64))__htab_map_lookup_elem);
495 	*insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 1);
496 	*insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
497 				offsetof(struct htab_elem, key) +
498 				round_up(map->key_size, 8));
499 	return insn - insn_buf;
500 }
501 
502 static void *htab_lru_map_lookup_elem(struct bpf_map *map, void *key)
503 {
504 	struct htab_elem *l = __htab_map_lookup_elem(map, key);
505 
506 	if (l) {
507 		bpf_lru_node_set_ref(&l->lru_node);
508 		return l->key + round_up(map->key_size, 8);
509 	}
510 
511 	return NULL;
512 }
513 
514 static u32 htab_lru_map_gen_lookup(struct bpf_map *map,
515 				   struct bpf_insn *insn_buf)
516 {
517 	struct bpf_insn *insn = insn_buf;
518 	const int ret = BPF_REG_0;
519 	const int ref_reg = BPF_REG_1;
520 
521 	*insn++ = BPF_EMIT_CALL((u64 (*)(u64, u64, u64, u64, u64))__htab_map_lookup_elem);
522 	*insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 4);
523 	*insn++ = BPF_LDX_MEM(BPF_B, ref_reg, ret,
524 			      offsetof(struct htab_elem, lru_node) +
525 			      offsetof(struct bpf_lru_node, ref));
526 	*insn++ = BPF_JMP_IMM(BPF_JNE, ref_reg, 0, 1);
527 	*insn++ = BPF_ST_MEM(BPF_B, ret,
528 			     offsetof(struct htab_elem, lru_node) +
529 			     offsetof(struct bpf_lru_node, ref),
530 			     1);
531 	*insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
532 				offsetof(struct htab_elem, key) +
533 				round_up(map->key_size, 8));
534 	return insn - insn_buf;
535 }
536 
537 /* It is called from the bpf_lru_list when the LRU needs to delete
538  * older elements from the htab.
539  */
540 static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node)
541 {
542 	struct bpf_htab *htab = (struct bpf_htab *)arg;
543 	struct htab_elem *l = NULL, *tgt_l;
544 	struct hlist_nulls_head *head;
545 	struct hlist_nulls_node *n;
546 	unsigned long flags;
547 	struct bucket *b;
548 
549 	tgt_l = container_of(node, struct htab_elem, lru_node);
550 	b = __select_bucket(htab, tgt_l->hash);
551 	head = &b->head;
552 
553 	raw_spin_lock_irqsave(&b->lock, flags);
554 
555 	hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
556 		if (l == tgt_l) {
557 			hlist_nulls_del_rcu(&l->hash_node);
558 			break;
559 		}
560 
561 	raw_spin_unlock_irqrestore(&b->lock, flags);
562 
563 	return l == tgt_l;
564 }
565 
566 /* Called from syscall */
567 static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
568 {
569 	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
570 	struct hlist_nulls_head *head;
571 	struct htab_elem *l, *next_l;
572 	u32 hash, key_size;
573 	int i = 0;
574 
575 	WARN_ON_ONCE(!rcu_read_lock_held());
576 
577 	key_size = map->key_size;
578 
579 	if (!key)
580 		goto find_first_elem;
581 
582 	hash = htab_map_hash(key, key_size);
583 
584 	head = select_bucket(htab, hash);
585 
586 	/* lookup the key */
587 	l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);
588 
589 	if (!l)
590 		goto find_first_elem;
591 
592 	/* key was found, get next key in the same bucket */
593 	next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_next_rcu(&l->hash_node)),
594 				  struct htab_elem, hash_node);
595 
596 	if (next_l) {
597 		/* if next elem in this hash list is non-zero, just return it */
598 		memcpy(next_key, next_l->key, key_size);
599 		return 0;
600 	}
601 
602 	/* no more elements in this hash list, go to the next bucket */
603 	i = hash & (htab->n_buckets - 1);
604 	i++;
605 
606 find_first_elem:
607 	/* iterate over buckets */
608 	for (; i < htab->n_buckets; i++) {
609 		head = select_bucket(htab, i);
610 
611 		/* pick first element in the bucket */
612 		next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_first_rcu(head)),
613 					  struct htab_elem, hash_node);
614 		if (next_l) {
615 			/* if it's not empty, just return it */
616 			memcpy(next_key, next_l->key, key_size);
617 			return 0;
618 		}
619 	}
620 
621 	/* iterated over all buckets and all elements */
622 	return -ENOENT;
623 }
624 
625 static void htab_elem_free(struct bpf_htab *htab, struct htab_elem *l)
626 {
627 	if (htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH)
628 		free_percpu(htab_elem_get_ptr(l, htab->map.key_size));
629 	kfree(l);
630 }
631 
632 static void htab_elem_free_rcu(struct rcu_head *head)
633 {
634 	struct htab_elem *l = container_of(head, struct htab_elem, rcu);
635 	struct bpf_htab *htab = l->htab;
636 
637 	/* must increment bpf_prog_active to avoid kprobe+bpf triggering while
638 	 * we're calling kfree, otherwise deadlock is possible if kprobes
639 	 * are placed somewhere inside of slub
640 	 */
641 	preempt_disable();
642 	__this_cpu_inc(bpf_prog_active);
643 	htab_elem_free(htab, l);
644 	__this_cpu_dec(bpf_prog_active);
645 	preempt_enable();
646 }
647 
648 static void free_htab_elem(struct bpf_htab *htab, struct htab_elem *l)
649 {
650 	struct bpf_map *map = &htab->map;
651 
652 	if (map->ops->map_fd_put_ptr) {
653 		void *ptr = fd_htab_map_get_ptr(map, l);
654 
655 		map->ops->map_fd_put_ptr(ptr);
656 	}
657 
658 	if (htab_is_prealloc(htab)) {
659 		pcpu_freelist_push(&htab->freelist, &l->fnode);
660 	} else {
661 		atomic_dec(&htab->count);
662 		l->htab = htab;
663 		call_rcu(&l->rcu, htab_elem_free_rcu);
664 	}
665 }
666 
667 static void pcpu_copy_value(struct bpf_htab *htab, void __percpu *pptr,
668 			    void *value, bool onallcpus)
669 {
670 	if (!onallcpus) {
671 		/* copy true value_size bytes */
672 		memcpy(this_cpu_ptr(pptr), value, htab->map.value_size);
673 	} else {
674 		u32 size = round_up(htab->map.value_size, 8);
675 		int off = 0, cpu;
676 
677 		for_each_possible_cpu(cpu) {
678 			bpf_long_memcpy(per_cpu_ptr(pptr, cpu),
679 					value + off, size);
680 			off += size;
681 		}
682 	}
683 }
684 
685 static bool fd_htab_map_needs_adjust(const struct bpf_htab *htab)
686 {
687 	return htab->map.map_type == BPF_MAP_TYPE_HASH_OF_MAPS &&
688 	       BITS_PER_LONG == 64;
689 }
690 
691 static u32 htab_size_value(const struct bpf_htab *htab, bool percpu)
692 {
693 	u32 size = htab->map.value_size;
694 
695 	if (percpu || fd_htab_map_needs_adjust(htab))
696 		size = round_up(size, 8);
697 	return size;
698 }
699 
700 static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
701 					 void *value, u32 key_size, u32 hash,
702 					 bool percpu, bool onallcpus,
703 					 struct htab_elem *old_elem)
704 {
705 	u32 size = htab_size_value(htab, percpu);
706 	bool prealloc = htab_is_prealloc(htab);
707 	struct htab_elem *l_new, **pl_new;
708 	void __percpu *pptr;
709 
710 	if (prealloc) {
711 		if (old_elem) {
712 			/* if we're updating the existing element,
713 			 * use per-cpu extra elems to avoid freelist_pop/push
714 			 */
715 			pl_new = this_cpu_ptr(htab->extra_elems);
716 			l_new = *pl_new;
717 			*pl_new = old_elem;
718 		} else {
719 			struct pcpu_freelist_node *l;
720 
721 			l = pcpu_freelist_pop(&htab->freelist);
722 			if (!l)
723 				return ERR_PTR(-E2BIG);
724 			l_new = container_of(l, struct htab_elem, fnode);
725 		}
726 	} else {
727 		if (atomic_inc_return(&htab->count) > htab->map.max_entries)
728 			if (!old_elem) {
729 				/* when map is full and update() is replacing
730 				 * old element, it's ok to allocate, since
731 				 * old element will be freed immediately.
732 				 * Otherwise return an error
733 				 */
734 				atomic_dec(&htab->count);
735 				return ERR_PTR(-E2BIG);
736 			}
737 		l_new = kmalloc_node(htab->elem_size, GFP_ATOMIC | __GFP_NOWARN,
738 				     htab->map.numa_node);
739 		if (!l_new)
740 			return ERR_PTR(-ENOMEM);
741 	}
742 
743 	memcpy(l_new->key, key, key_size);
744 	if (percpu) {
745 		if (prealloc) {
746 			pptr = htab_elem_get_ptr(l_new, key_size);
747 		} else {
748 			/* alloc_percpu zero-fills */
749 			pptr = __alloc_percpu_gfp(size, 8,
750 						  GFP_ATOMIC | __GFP_NOWARN);
751 			if (!pptr) {
752 				kfree(l_new);
753 				return ERR_PTR(-ENOMEM);
754 			}
755 		}
756 
757 		pcpu_copy_value(htab, pptr, value, onallcpus);
758 
759 		if (!prealloc)
760 			htab_elem_set_ptr(l_new, key_size, pptr);
761 	} else {
762 		memcpy(l_new->key + round_up(key_size, 8), value, size);
763 	}
764 
765 	l_new->hash = hash;
766 	return l_new;
767 }
768 
769 static int check_flags(struct bpf_htab *htab, struct htab_elem *l_old,
770 		       u64 map_flags)
771 {
772 	if (l_old && map_flags == BPF_NOEXIST)
773 		/* elem already exists */
774 		return -EEXIST;
775 
776 	if (!l_old && map_flags == BPF_EXIST)
777 		/* elem doesn't exist, cannot update it */
778 		return -ENOENT;
779 
780 	return 0;
781 }
782 
783 /* Called from syscall or from eBPF program */
784 static int htab_map_update_elem(struct bpf_map *map, void *key, void *value,
785 				u64 map_flags)
786 {
787 	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
788 	struct htab_elem *l_new = NULL, *l_old;
789 	struct hlist_nulls_head *head;
790 	unsigned long flags;
791 	struct bucket *b;
792 	u32 key_size, hash;
793 	int ret;
794 
795 	if (unlikely(map_flags > BPF_EXIST))
796 		/* unknown flags */
797 		return -EINVAL;
798 
799 	WARN_ON_ONCE(!rcu_read_lock_held());
800 
801 	key_size = map->key_size;
802 
803 	hash = htab_map_hash(key, key_size);
804 
805 	b = __select_bucket(htab, hash);
806 	head = &b->head;
807 
808 	/* bpf_map_update_elem() can be called in_irq() */
809 	raw_spin_lock_irqsave(&b->lock, flags);
810 
811 	l_old = lookup_elem_raw(head, hash, key, key_size);
812 
813 	ret = check_flags(htab, l_old, map_flags);
814 	if (ret)
815 		goto err;
816 
817 	l_new = alloc_htab_elem(htab, key, value, key_size, hash, false, false,
818 				l_old);
819 	if (IS_ERR(l_new)) {
820 		/* all pre-allocated elements are in use or memory exhausted */
821 		ret = PTR_ERR(l_new);
822 		goto err;
823 	}
824 
825 	/* add new element to the head of the list, so that
826 	 * concurrent search will find it before old elem
827 	 */
828 	hlist_nulls_add_head_rcu(&l_new->hash_node, head);
829 	if (l_old) {
830 		hlist_nulls_del_rcu(&l_old->hash_node);
831 		if (!htab_is_prealloc(htab))
832 			free_htab_elem(htab, l_old);
833 	}
834 	ret = 0;
835 err:
836 	raw_spin_unlock_irqrestore(&b->lock, flags);
837 	return ret;
838 }
839 
840 static int htab_lru_map_update_elem(struct bpf_map *map, void *key, void *value,
841 				    u64 map_flags)
842 {
843 	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
844 	struct htab_elem *l_new, *l_old = NULL;
845 	struct hlist_nulls_head *head;
846 	unsigned long flags;
847 	struct bucket *b;
848 	u32 key_size, hash;
849 	int ret;
850 
851 	if (unlikely(map_flags > BPF_EXIST))
852 		/* unknown flags */
853 		return -EINVAL;
854 
855 	WARN_ON_ONCE(!rcu_read_lock_held());
856 
857 	key_size = map->key_size;
858 
859 	hash = htab_map_hash(key, key_size);
860 
861 	b = __select_bucket(htab, hash);
862 	head = &b->head;
863 
864 	/* For LRU, we need to alloc before taking bucket's
865 	 * spinlock because getting free nodes from LRU may need
866 	 * to remove older elements from htab and this removal
867 	 * operation will need a bucket lock.
868 	 */
869 	l_new = prealloc_lru_pop(htab, key, hash);
870 	if (!l_new)
871 		return -ENOMEM;
872 	memcpy(l_new->key + round_up(map->key_size, 8), value, map->value_size);
873 
874 	/* bpf_map_update_elem() can be called in_irq() */
875 	raw_spin_lock_irqsave(&b->lock, flags);
876 
877 	l_old = lookup_elem_raw(head, hash, key, key_size);
878 
879 	ret = check_flags(htab, l_old, map_flags);
880 	if (ret)
881 		goto err;
882 
883 	/* add new element to the head of the list, so that
884 	 * concurrent search will find it before old elem
885 	 */
886 	hlist_nulls_add_head_rcu(&l_new->hash_node, head);
887 	if (l_old) {
888 		bpf_lru_node_set_ref(&l_new->lru_node);
889 		hlist_nulls_del_rcu(&l_old->hash_node);
890 	}
891 	ret = 0;
892 
893 err:
894 	raw_spin_unlock_irqrestore(&b->lock, flags);
895 
896 	if (ret)
897 		bpf_lru_push_free(&htab->lru, &l_new->lru_node);
898 	else if (l_old)
899 		bpf_lru_push_free(&htab->lru, &l_old->lru_node);
900 
901 	return ret;
902 }
903 
904 static int __htab_percpu_map_update_elem(struct bpf_map *map, void *key,
905 					 void *value, u64 map_flags,
906 					 bool onallcpus)
907 {
908 	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
909 	struct htab_elem *l_new = NULL, *l_old;
910 	struct hlist_nulls_head *head;
911 	unsigned long flags;
912 	struct bucket *b;
913 	u32 key_size, hash;
914 	int ret;
915 
916 	if (unlikely(map_flags > BPF_EXIST))
917 		/* unknown flags */
918 		return -EINVAL;
919 
920 	WARN_ON_ONCE(!rcu_read_lock_held());
921 
922 	key_size = map->key_size;
923 
924 	hash = htab_map_hash(key, key_size);
925 
926 	b = __select_bucket(htab, hash);
927 	head = &b->head;
928 
929 	/* bpf_map_update_elem() can be called in_irq() */
930 	raw_spin_lock_irqsave(&b->lock, flags);
931 
932 	l_old = lookup_elem_raw(head, hash, key, key_size);
933 
934 	ret = check_flags(htab, l_old, map_flags);
935 	if (ret)
936 		goto err;
937 
938 	if (l_old) {
939 		/* per-cpu hash map can update value in-place */
940 		pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),
941 				value, onallcpus);
942 	} else {
943 		l_new = alloc_htab_elem(htab, key, value, key_size,
944 					hash, true, onallcpus, NULL);
945 		if (IS_ERR(l_new)) {
946 			ret = PTR_ERR(l_new);
947 			goto err;
948 		}
949 		hlist_nulls_add_head_rcu(&l_new->hash_node, head);
950 	}
951 	ret = 0;
952 err:
953 	raw_spin_unlock_irqrestore(&b->lock, flags);
954 	return ret;
955 }
956 
957 static int __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
958 					     void *value, u64 map_flags,
959 					     bool onallcpus)
960 {
961 	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
962 	struct htab_elem *l_new = NULL, *l_old;
963 	struct hlist_nulls_head *head;
964 	unsigned long flags;
965 	struct bucket *b;
966 	u32 key_size, hash;
967 	int ret;
968 
969 	if (unlikely(map_flags > BPF_EXIST))
970 		/* unknown flags */
971 		return -EINVAL;
972 
973 	WARN_ON_ONCE(!rcu_read_lock_held());
974 
975 	key_size = map->key_size;
976 
977 	hash = htab_map_hash(key, key_size);
978 
979 	b = __select_bucket(htab, hash);
980 	head = &b->head;
981 
982 	/* For LRU, we need to alloc before taking bucket's
983 	 * spinlock because LRU's elem alloc may need
984 	 * to remove older elem from htab and this removal
985 	 * operation will need a bucket lock.
986 	 */
987 	if (map_flags != BPF_EXIST) {
988 		l_new = prealloc_lru_pop(htab, key, hash);
989 		if (!l_new)
990 			return -ENOMEM;
991 	}
992 
993 	/* bpf_map_update_elem() can be called in_irq() */
994 	raw_spin_lock_irqsave(&b->lock, flags);
995 
996 	l_old = lookup_elem_raw(head, hash, key, key_size);
997 
998 	ret = check_flags(htab, l_old, map_flags);
999 	if (ret)
1000 		goto err;
1001 
1002 	if (l_old) {
1003 		bpf_lru_node_set_ref(&l_old->lru_node);
1004 
1005 		/* per-cpu hash map can update value in-place */
1006 		pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),
1007 				value, onallcpus);
1008 	} else {
1009 		pcpu_copy_value(htab, htab_elem_get_ptr(l_new, key_size),
1010 				value, onallcpus);
1011 		hlist_nulls_add_head_rcu(&l_new->hash_node, head);
1012 		l_new = NULL;
1013 	}
1014 	ret = 0;
1015 err:
1016 	raw_spin_unlock_irqrestore(&b->lock, flags);
1017 	if (l_new)
1018 		bpf_lru_push_free(&htab->lru, &l_new->lru_node);
1019 	return ret;
1020 }
1021 
1022 static int htab_percpu_map_update_elem(struct bpf_map *map, void *key,
1023 				       void *value, u64 map_flags)
1024 {
1025 	return __htab_percpu_map_update_elem(map, key, value, map_flags, false);
1026 }
1027 
1028 static int htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
1029 					   void *value, u64 map_flags)
1030 {
1031 	return __htab_lru_percpu_map_update_elem(map, key, value, map_flags,
1032 						 false);
1033 }
1034 
1035 /* Called from syscall or from eBPF program */
1036 static int htab_map_delete_elem(struct bpf_map *map, void *key)
1037 {
1038 	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1039 	struct hlist_nulls_head *head;
1040 	struct bucket *b;
1041 	struct htab_elem *l;
1042 	unsigned long flags;
1043 	u32 hash, key_size;
1044 	int ret = -ENOENT;
1045 
1046 	WARN_ON_ONCE(!rcu_read_lock_held());
1047 
1048 	key_size = map->key_size;
1049 
1050 	hash = htab_map_hash(key, key_size);
1051 	b = __select_bucket(htab, hash);
1052 	head = &b->head;
1053 
1054 	raw_spin_lock_irqsave(&b->lock, flags);
1055 
1056 	l = lookup_elem_raw(head, hash, key, key_size);
1057 
1058 	if (l) {
1059 		hlist_nulls_del_rcu(&l->hash_node);
1060 		free_htab_elem(htab, l);
1061 		ret = 0;
1062 	}
1063 
1064 	raw_spin_unlock_irqrestore(&b->lock, flags);
1065 	return ret;
1066 }
1067 
1068 static int htab_lru_map_delete_elem(struct bpf_map *map, void *key)
1069 {
1070 	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1071 	struct hlist_nulls_head *head;
1072 	struct bucket *b;
1073 	struct htab_elem *l;
1074 	unsigned long flags;
1075 	u32 hash, key_size;
1076 	int ret = -ENOENT;
1077 
1078 	WARN_ON_ONCE(!rcu_read_lock_held());
1079 
1080 	key_size = map->key_size;
1081 
1082 	hash = htab_map_hash(key, key_size);
1083 	b = __select_bucket(htab, hash);
1084 	head = &b->head;
1085 
1086 	raw_spin_lock_irqsave(&b->lock, flags);
1087 
1088 	l = lookup_elem_raw(head, hash, key, key_size);
1089 
1090 	if (l) {
1091 		hlist_nulls_del_rcu(&l->hash_node);
1092 		ret = 0;
1093 	}
1094 
1095 	raw_spin_unlock_irqrestore(&b->lock, flags);
1096 	if (l)
1097 		bpf_lru_push_free(&htab->lru, &l->lru_node);
1098 	return ret;
1099 }
1100 
1101 static void delete_all_elements(struct bpf_htab *htab)
1102 {
1103 	int i;
1104 
1105 	for (i = 0; i < htab->n_buckets; i++) {
1106 		struct hlist_nulls_head *head = select_bucket(htab, i);
1107 		struct hlist_nulls_node *n;
1108 		struct htab_elem *l;
1109 
1110 		hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
1111 			hlist_nulls_del_rcu(&l->hash_node);
1112 			htab_elem_free(htab, l);
1113 		}
1114 	}
1115 }
1116 
1117 /* Called when map->refcnt goes to zero, either from workqueue or from syscall */
1118 static void htab_map_free(struct bpf_map *map)
1119 {
1120 	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1121 
1122 	/* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
1123 	 * so the programs (can be more than one that used this map) were
1124 	 * disconnected from events. Wait for outstanding critical sections in
1125 	 * these programs to complete
1126 	 */
1127 	synchronize_rcu();
1128 
1129 	/* some of free_htab_elem() callbacks for elements of this map may
1130 	 * not have executed. Wait for them.
1131 	 */
1132 	rcu_barrier();
1133 	if (!htab_is_prealloc(htab))
1134 		delete_all_elements(htab);
1135 	else
1136 		prealloc_destroy(htab);
1137 
1138 	free_percpu(htab->extra_elems);
1139 	bpf_map_area_free(htab->buckets);
1140 	kfree(htab);
1141 }
1142 
1143 const struct bpf_map_ops htab_map_ops = {
1144 	.map_alloc = htab_map_alloc,
1145 	.map_free = htab_map_free,
1146 	.map_get_next_key = htab_map_get_next_key,
1147 	.map_lookup_elem = htab_map_lookup_elem,
1148 	.map_update_elem = htab_map_update_elem,
1149 	.map_delete_elem = htab_map_delete_elem,
1150 	.map_gen_lookup = htab_map_gen_lookup,
1151 };
1152 
1153 const struct bpf_map_ops htab_lru_map_ops = {
1154 	.map_alloc = htab_map_alloc,
1155 	.map_free = htab_map_free,
1156 	.map_get_next_key = htab_map_get_next_key,
1157 	.map_lookup_elem = htab_lru_map_lookup_elem,
1158 	.map_update_elem = htab_lru_map_update_elem,
1159 	.map_delete_elem = htab_lru_map_delete_elem,
1160 	.map_gen_lookup = htab_lru_map_gen_lookup,
1161 };
1162 
1163 /* Called from eBPF program */
1164 static void *htab_percpu_map_lookup_elem(struct bpf_map *map, void *key)
1165 {
1166 	struct htab_elem *l = __htab_map_lookup_elem(map, key);
1167 
1168 	if (l)
1169 		return this_cpu_ptr(htab_elem_get_ptr(l, map->key_size));
1170 	else
1171 		return NULL;
1172 }
1173 
1174 static void *htab_lru_percpu_map_lookup_elem(struct bpf_map *map, void *key)
1175 {
1176 	struct htab_elem *l = __htab_map_lookup_elem(map, key);
1177 
1178 	if (l) {
1179 		bpf_lru_node_set_ref(&l->lru_node);
1180 		return this_cpu_ptr(htab_elem_get_ptr(l, map->key_size));
1181 	}
1182 
1183 	return NULL;
1184 }
1185 
1186 int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value)
1187 {
1188 	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1189 	struct htab_elem *l;
1190 	void __percpu *pptr;
1191 	int ret = -ENOENT;
1192 	int cpu, off = 0;
1193 	u32 size;
1194 
1195 	/* per_cpu areas are zero-filled and bpf programs can only
1196 	 * access 'value_size' of them, so copying rounded areas
1197 	 * will not leak any kernel data
1198 	 */
1199 	size = round_up(map->value_size, 8);
1200 	rcu_read_lock();
1201 	l = __htab_map_lookup_elem(map, key);
1202 	if (!l)
1203 		goto out;
1204 	if (htab_is_lru(htab))
1205 		bpf_lru_node_set_ref(&l->lru_node);
1206 	pptr = htab_elem_get_ptr(l, map->key_size);
1207 	for_each_possible_cpu(cpu) {
1208 		bpf_long_memcpy(value + off,
1209 				per_cpu_ptr(pptr, cpu), size);
1210 		off += size;
1211 	}
1212 	ret = 0;
1213 out:
1214 	rcu_read_unlock();
1215 	return ret;
1216 }
1217 
1218 int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value,
1219 			   u64 map_flags)
1220 {
1221 	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1222 	int ret;
1223 
1224 	rcu_read_lock();
1225 	if (htab_is_lru(htab))
1226 		ret = __htab_lru_percpu_map_update_elem(map, key, value,
1227 							map_flags, true);
1228 	else
1229 		ret = __htab_percpu_map_update_elem(map, key, value, map_flags,
1230 						    true);
1231 	rcu_read_unlock();
1232 
1233 	return ret;
1234 }
1235 
1236 const struct bpf_map_ops htab_percpu_map_ops = {
1237 	.map_alloc = htab_map_alloc,
1238 	.map_free = htab_map_free,
1239 	.map_get_next_key = htab_map_get_next_key,
1240 	.map_lookup_elem = htab_percpu_map_lookup_elem,
1241 	.map_update_elem = htab_percpu_map_update_elem,
1242 	.map_delete_elem = htab_map_delete_elem,
1243 };
1244 
1245 const struct bpf_map_ops htab_lru_percpu_map_ops = {
1246 	.map_alloc = htab_map_alloc,
1247 	.map_free = htab_map_free,
1248 	.map_get_next_key = htab_map_get_next_key,
1249 	.map_lookup_elem = htab_lru_percpu_map_lookup_elem,
1250 	.map_update_elem = htab_lru_percpu_map_update_elem,
1251 	.map_delete_elem = htab_lru_map_delete_elem,
1252 };
1253 
1254 static struct bpf_map *fd_htab_map_alloc(union bpf_attr *attr)
1255 {
1256 	if (attr->value_size != sizeof(u32))
1257 		return ERR_PTR(-EINVAL);
1258 	return htab_map_alloc(attr);
1259 }
1260 
1261 static void fd_htab_map_free(struct bpf_map *map)
1262 {
1263 	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1264 	struct hlist_nulls_node *n;
1265 	struct hlist_nulls_head *head;
1266 	struct htab_elem *l;
1267 	int i;
1268 
1269 	for (i = 0; i < htab->n_buckets; i++) {
1270 		head = select_bucket(htab, i);
1271 
1272 		hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
1273 			void *ptr = fd_htab_map_get_ptr(map, l);
1274 
1275 			map->ops->map_fd_put_ptr(ptr);
1276 		}
1277 	}
1278 
1279 	htab_map_free(map);
1280 }
1281 
1282 /* only called from syscall */
1283 int bpf_fd_htab_map_lookup_elem(struct bpf_map *map, void *key, u32 *value)
1284 {
1285 	void **ptr;
1286 	int ret = 0;
1287 
1288 	if (!map->ops->map_fd_sys_lookup_elem)
1289 		return -ENOTSUPP;
1290 
1291 	rcu_read_lock();
1292 	ptr = htab_map_lookup_elem(map, key);
1293 	if (ptr)
1294 		*value = map->ops->map_fd_sys_lookup_elem(READ_ONCE(*ptr));
1295 	else
1296 		ret = -ENOENT;
1297 	rcu_read_unlock();
1298 
1299 	return ret;
1300 }
1301 
1302 /* only called from syscall */
1303 int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file,
1304 				void *key, void *value, u64 map_flags)
1305 {
1306 	void *ptr;
1307 	int ret;
1308 	u32 ufd = *(u32 *)value;
1309 
1310 	ptr = map->ops->map_fd_get_ptr(map, map_file, ufd);
1311 	if (IS_ERR(ptr))
1312 		return PTR_ERR(ptr);
1313 
1314 	ret = htab_map_update_elem(map, key, &ptr, map_flags);
1315 	if (ret)
1316 		map->ops->map_fd_put_ptr(ptr);
1317 
1318 	return ret;
1319 }
1320 
1321 static struct bpf_map *htab_of_map_alloc(union bpf_attr *attr)
1322 {
1323 	struct bpf_map *map, *inner_map_meta;
1324 
1325 	inner_map_meta = bpf_map_meta_alloc(attr->inner_map_fd);
1326 	if (IS_ERR(inner_map_meta))
1327 		return inner_map_meta;
1328 
1329 	map = fd_htab_map_alloc(attr);
1330 	if (IS_ERR(map)) {
1331 		bpf_map_meta_free(inner_map_meta);
1332 		return map;
1333 	}
1334 
1335 	map->inner_map_meta = inner_map_meta;
1336 
1337 	return map;
1338 }
1339 
1340 static void *htab_of_map_lookup_elem(struct bpf_map *map, void *key)
1341 {
1342 	struct bpf_map **inner_map  = htab_map_lookup_elem(map, key);
1343 
1344 	if (!inner_map)
1345 		return NULL;
1346 
1347 	return READ_ONCE(*inner_map);
1348 }
1349 
1350 static u32 htab_of_map_gen_lookup(struct bpf_map *map,
1351 				  struct bpf_insn *insn_buf)
1352 {
1353 	struct bpf_insn *insn = insn_buf;
1354 	const int ret = BPF_REG_0;
1355 
1356 	*insn++ = BPF_EMIT_CALL((u64 (*)(u64, u64, u64, u64, u64))__htab_map_lookup_elem);
1357 	*insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 2);
1358 	*insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
1359 				offsetof(struct htab_elem, key) +
1360 				round_up(map->key_size, 8));
1361 	*insn++ = BPF_LDX_MEM(BPF_DW, ret, ret, 0);
1362 
1363 	return insn - insn_buf;
1364 }
1365 
1366 static void htab_of_map_free(struct bpf_map *map)
1367 {
1368 	bpf_map_meta_free(map->inner_map_meta);
1369 	fd_htab_map_free(map);
1370 }
1371 
1372 const struct bpf_map_ops htab_of_maps_map_ops = {
1373 	.map_alloc = htab_of_map_alloc,
1374 	.map_free = htab_of_map_free,
1375 	.map_get_next_key = htab_map_get_next_key,
1376 	.map_lookup_elem = htab_of_map_lookup_elem,
1377 	.map_delete_elem = htab_map_delete_elem,
1378 	.map_fd_get_ptr = bpf_map_fd_get_ptr,
1379 	.map_fd_put_ptr = bpf_map_fd_put_ptr,
1380 	.map_fd_sys_lookup_elem = bpf_map_fd_sys_lookup_elem,
1381 	.map_gen_lookup = htab_of_map_gen_lookup,
1382 };
1383