kernel/bpf/hashtab.c

   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
  24 struct bucket {
  25         struct hlist_nulls_head head;
  26         raw_spinlock_t lock;
  27 };
  28
  29 struct bpf_htab {
  30         struct bpf_map map;
  31         struct bucket *buckets;
  32         void *elems;
  33         union {
  34                 struct pcpu_freelist freelist;
  35                 struct bpf_lru lru;
  36         };
  37         struct htab_elem *__percpu *extra_elems;
  38         atomic_t count; /* number of elements in this hashtable */
  39         u32 n_buckets;  /* number of hash buckets */
  40         u32 elem_size;  /* size of each element in bytes */
  41 };
  42
  43 /* each htab element is struct htab_elem + key + value */
  44 struct htab_elem {
  45         union {
  46                 struct hlist_nulls_node hash_node;
  47                 struct {
  48                         void *padding;
  49                         union {
  50                                 struct bpf_htab *htab;
  51                                 struct pcpu_freelist_node fnode;
  52                         };
  53                 };
  54         };
  55         union {
  56                 struct rcu_head rcu;
  57                 struct bpf_lru_node lru_node;
  58         };
  59         u32 hash;
  60         char key[0] __aligned(8);
  61 };
  62
  63 static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node);
  64
  65 static bool htab_is_lru(const struct bpf_htab *htab)
  66 {
  67         return htab->map.map_type == BPF_MAP_TYPE_LRU_HASH ||
  68                 htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;
  69 }
  70
  71 static bool htab_is_percpu(const struct bpf_htab *htab)
  72 {
  73         return htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH ||
  74                 htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;
  75 }
  76
  77 static bool htab_is_prealloc(const struct bpf_htab *htab)
  78 {
  79         return !(htab->map.map_flags & BPF_F_NO_PREALLOC);
  80 }
  81
  82 static inline void htab_elem_set_ptr(struct htab_elem *l, u32 key_size,
  83                                      void __percpu *pptr)
  84 {
  85         *(void __percpu **)(l->key + key_size) = pptr;
  86 }
  87
  88 static inline void __percpu *htab_elem_get_ptr(struct htab_elem *l, u32 key_size)
  89 {
  90         return *(void __percpu **)(l->key + key_size);
  91 }
  92
  93 static void *fd_htab_map_get_ptr(const struct bpf_map *map, struct htab_elem *l)
  94 {
  95         return *(void **)(l->key + roundup(map->key_size, 8));
  96 }
  97
  98 static struct htab_elem *get_htab_elem(struct bpf_htab *htab, int i)
  99 {
 100         return (struct htab_elem *) (htab->elems + i * htab->elem_size);
 101 }
 102
 103 static void htab_free_elems(struct bpf_htab *htab)
 104 {
 105         int i;
 106
 107         if (!htab_is_percpu(htab))
 108                 goto free_elems;
 109
 110         for (i = 0; i < htab->map.max_entries; i++) {
 111                 void __percpu *pptr;
 112
 113                 pptr = htab_elem_get_ptr(get_htab_elem(htab, i),
 114                                          htab->map.key_size);
 115                 free_percpu(pptr);
 116         }
 117 free_elems:
 118         bpf_map_area_free(htab->elems);
 119 }
 120
 121 static struct htab_elem *prealloc_lru_pop(struct bpf_htab *htab, void *key,
 122                                           u32 hash)
 123 {
 124         struct bpf_lru_node *node = bpf_lru_pop_free(&htab->lru, hash);
 125         struct htab_elem *l;
 126
 127         if (node) {
 128                 l = container_of(node, struct htab_elem, lru_node);
 129                 memcpy(l->key, key, htab->map.key_size);
 130                 return l;
 131         }
 132
 133         return NULL;
 134 }
 135
 136 static int prealloc_init(struct bpf_htab *htab)
 137 {
 138         u32 num_entries = htab->map.max_entries;
 139         int err = -ENOMEM, i;
 140
 141         if (!htab_is_percpu(htab) && !htab_is_lru(htab))
 142                 num_entries += num_possible_cpus();
 143
 144         htab->elems = bpf_map_area_alloc(htab->elem_size * num_entries,
 145                                          htab->map.numa_node);
 146         if (!htab->elems)
 147                 return -ENOMEM;
 148
 149         if (!htab_is_percpu(htab))
 150                 goto skip_percpu_elems;
 151
 152         for (i = 0; i < num_entries; i++) {
 153                 u32 size = round_up(htab->map.value_size, 8);
 154                 void __percpu *pptr;
 155
 156                 pptr = __alloc_percpu_gfp(size, 8, GFP_USER | __GFP_NOWARN);
 157                 if (!pptr)
 158                         goto free_elems;
 159                 htab_elem_set_ptr(get_htab_elem(htab, i), htab->map.key_size,
 160                                   pptr);
 161         }
 162
 163 skip_percpu_elems:
 164         if (htab_is_lru(htab))
 165                 err = bpf_lru_init(&htab->lru,
 166                                    htab->map.map_flags & BPF_F_NO_COMMON_LRU,
 167                                    offsetof(struct htab_elem, hash) -
 168                                    offsetof(struct htab_elem, lru_node),
 169                                    htab_lru_map_delete_node,
 170                                    htab);
 171         else
 172                 err = pcpu_freelist_init(&htab->freelist);
 173
 174         if (err)
 175                 goto free_elems;
 176
 177         if (htab_is_lru(htab))
 178                 bpf_lru_populate(&htab->lru, htab->elems,
 179                                  offsetof(struct htab_elem, lru_node),
 180                                  htab->elem_size, num_entries);
 181         else
 182                 pcpu_freelist_populate(&htab->freelist,
 183                                        htab->elems + offsetof(struct htab_elem, fnode),
 184                                        htab->elem_size, num_entries);
 185
 186         return 0;
 187
 188 free_elems:
 189         htab_free_elems(htab);
 190         return err;
 191 }
 192
 193 static void prealloc_destroy(struct bpf_htab *htab)
 194 {
 195         htab_free_elems(htab);
 196
 197         if (htab_is_lru(htab))
 198                 bpf_lru_destroy(&htab->lru);
 199         else
 200                 pcpu_freelist_destroy(&htab->freelist);
 201 }
 202
 203 static int alloc_extra_elems(struct bpf_htab *htab)
 204 {
 205         struct htab_elem *__percpu *pptr, *l_new;
 206         struct pcpu_freelist_node *l;
 207         int cpu;
 208
 209         pptr = __alloc_percpu_gfp(sizeof(struct htab_elem *), 8,
 210                                   GFP_USER | __GFP_NOWARN);
 211         if (!pptr)
 212                 return -ENOMEM;
 213
 214         for_each_possible_cpu(cpu) {
 215                 l = pcpu_freelist_pop(&htab->freelist);
 216                 /* pop will succeed, since prealloc_init()
 217                  * preallocated extra num_possible_cpus elements
 218                  */
 219                 l_new = container_of(l, struct htab_elem, fnode);
 220                 *per_cpu_ptr(pptr, cpu) = l_new;
 221         }
 222         htab->extra_elems = pptr;
 223         return 0;
 224 }
 225
 226 /* Called from syscall */
 227 static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
 228 {
 229         bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
 230                        attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
 231         bool lru = (attr->map_type == BPF_MAP_TYPE_LRU_HASH ||
 232                     attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
 233         /* percpu_lru means each cpu has its own LRU list.
 234          * it is different from BPF_MAP_TYPE_PERCPU_HASH where
 235          * the map's value itself is percpu.  percpu_lru has
 236          * nothing to do with the map's value.
 237          */
 238         bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU);
 239         bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC);
 240         int numa_node = bpf_map_attr_numa_node(attr);
 241         struct bpf_htab *htab;
 242         int err, i;
 243         u64 cost;
 244
 245         BUILD_BUG_ON(offsetof(struct htab_elem, htab) !=
 246                      offsetof(struct htab_elem, hash_node.pprev));
 247         BUILD_BUG_ON(offsetof(struct htab_elem, fnode.next) !=
 248                      offsetof(struct htab_elem, hash_node.pprev));
 249
 250         if (lru && !capable(CAP_SYS_ADMIN))
 251                 /* LRU implementation is much complicated than other
 252                  * maps.  Hence, limit to CAP_SYS_ADMIN for now.
 253                  */
 254                 return ERR_PTR(-EPERM);
 255
 256         if (attr->map_flags & ~HTAB_CREATE_FLAG_MASK)
 257                 /* reserved bits should not be used */
 258                 return ERR_PTR(-EINVAL);
 259
 260         if (!lru && percpu_lru)
 261                 return ERR_PTR(-EINVAL);
 262
 263         if (lru && !prealloc)
 264                 return ERR_PTR(-ENOTSUPP);
 265
 266         if (numa_node != NUMA_NO_NODE && (percpu || percpu_lru))
 267                 return ERR_PTR(-EINVAL);
 268
 269         htab = kzalloc(sizeof(*htab), GFP_USER);
 270         if (!htab)
 271                 return ERR_PTR(-ENOMEM);
 272
 273         /* mandatory map attributes */
 274         htab->map.map_type = attr->map_type;
 275         htab->map.key_size = attr->key_size;
 276         htab->map.value_size = attr->value_size;
 277         htab->map.max_entries = attr->max_entries;
 278         htab->map.map_flags = attr->map_flags;
 279         htab->map.numa_node = numa_node;
 280
 281         /* check sanity of attributes.
 282          * value_size == 0 may be allowed in the future to use map as a set
 283          */
 284         err = -EINVAL;
 285         if (htab->map.max_entries == 0 || htab->map.key_size == 0 ||
 286             htab->map.value_size == 0)
 287                 goto free_htab;
 288
 289         if (percpu_lru) {
 290                 /* ensure each CPU's lru list has >=1 elements.
 291                  * since we are at it, make each lru list has the same
 292                  * number of elements.
 293                  */
 294                 htab->map.max_entries = roundup(attr->max_entries,
 295                                                 num_possible_cpus());
 296                 if (htab->map.max_entries < attr->max_entries)
 297                         htab->map.max_entries = rounddown(attr->max_entries,
 298                                                           num_possible_cpus());
 299         }
 300
 301         /* hash table size must be power of 2 */
 302         htab->n_buckets = roundup_pow_of_two(htab->map.max_entries);
 303
 304         err = -E2BIG;
 305         if (htab->map.key_size > MAX_BPF_STACK)
 306                 /* eBPF programs initialize keys on stack, so they cannot be
 307                  * larger than max stack size
 308                  */
 309                 goto free_htab;
 310
 311         if (htab->map.value_size >= KMALLOC_MAX_SIZE -
 312             MAX_BPF_STACK - sizeof(struct htab_elem))
 313                 /* if value_size is bigger, the user space won't be able to
 314                  * access the elements via bpf syscall. This check also makes
 315                  * sure that the elem_size doesn't overflow and it's
 316                  * kmalloc-able later in htab_map_update_elem()
 317                  */
 318                 goto free_htab;
 319
 320         if (percpu && round_up(htab->map.value_size, 8) > PCPU_MIN_UNIT_SIZE)
 321                 /* make sure the size for pcpu_alloc() is reasonable */
 322                 goto free_htab;
 323
 324         htab->elem_size = sizeof(struct htab_elem) +
 325                           round_up(htab->map.key_size, 8);
 326         if (percpu)
 327                 htab->elem_size += sizeof(void *);
 328         else
 329                 htab->elem_size += round_up(htab->map.value_size, 8);
 330
 331         /* prevent zero size kmalloc and check for u32 overflow */
 332         if (htab->n_buckets == 0 ||
 333             htab->n_buckets > U32_MAX / sizeof(struct bucket))
 334                 goto free_htab;
 335
 336         cost = (u64) htab->n_buckets * sizeof(struct bucket) +
 337                (u64) htab->elem_size * htab->map.max_entries;
 338
 339         if (percpu)
 340                 cost += (u64) round_up(htab->map.value_size, 8) *
 341                         num_possible_cpus() * htab->map.max_entries;
 342         else
 343                cost += (u64) htab->elem_size * num_possible_cpus();
 344
 345         if (cost >= U32_MAX - PAGE_SIZE)
 346                 /* make sure page count doesn't overflow */
 347                 goto free_htab;
 348
 349         htab->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT;
 350
 351         /* if map size is larger than memlock limit, reject it early */
 352         err = bpf_map_precharge_memlock(htab->map.pages);
 353         if (err)
 354                 goto free_htab;
 355
 356         err = -ENOMEM;
 357         htab->buckets = bpf_map_area_alloc(htab->n_buckets *
 358                                            sizeof(struct bucket),
 359                                            htab->map.numa_node);
 360         if (!htab->buckets)
 361                 goto free_htab;
 362
 363         for (i = 0; i < htab->n_buckets; i++) {
 364                 INIT_HLIST_NULLS_HEAD(&htab->buckets[i].head, i);
 365                 raw_spin_lock_init(&htab->buckets[i].lock);
 366         }
 367
 368         if (prealloc) {
 369                 err = prealloc_init(htab);
 370                 if (err)
 371                         goto free_buckets;
 372
 373                 if (!percpu && !lru) {
 374                         /* lru itself can remove the least used element, so
 375                          * there is no need for an extra elem during map_update.
 376                          */
 377                         err = alloc_extra_elems(htab);
 378                         if (err)
 379                                 goto free_prealloc;
 380                 }
 381         }
 382
 383         return &htab->map;
 384
 385 free_prealloc:
 386         prealloc_destroy(htab);
 387 free_buckets:
 388         bpf_map_area_free(htab->buckets);
 389 free_htab:
 390         kfree(htab);
 391         return ERR_PTR(err);
 392 }
 393
 394 static inline u32 htab_map_hash(const void *key, u32 key_len)
 395 {
 396         return jhash(key, key_len, 0);
 397 }
 398
 399 static inline struct bucket *__select_bucket(struct bpf_htab *htab, u32 hash)
 400 {
 401         return &htab->buckets[hash & (htab->n_buckets - 1)];
 402 }
 403
 404 static inline struct hlist_nulls_head *select_bucket(struct bpf_htab *htab, u32 hash)
 405 {
 406         return &__select_bucket(htab, hash)->head;
 407 }
 408
 409 /* this lookup function can only be called with bucket lock taken */
 410 static struct htab_elem *lookup_elem_raw(struct hlist_nulls_head *head, u32 hash,
 411                                          void *key, u32 key_size)
 412 {
 413         struct hlist_nulls_node *n;
 414         struct htab_elem *l;
 415
 416         hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
 417                 if (l->hash == hash && !memcmp(&l->key, key, key_size))
 418                         return l;
 419
 420         return NULL;
 421 }
 422
 423 /* can be called without bucket lock. it will repeat the loop in
 424  * the unlikely event when elements moved from one bucket into another
 425  * while link list is being walked
 426  */
 427 static struct htab_elem *lookup_nulls_elem_raw(struct hlist_nulls_head *head,
 428                                                u32 hash, void *key,
 429                                                u32 key_size, u32 n_buckets)
 430 {
 431         struct hlist_nulls_node *n;
 432         struct htab_elem *l;
 433
 434 again:
 435         hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
 436                 if (l->hash == hash && !memcmp(&l->key, key, key_size))
 437                         return l;
 438
 439         if (unlikely(get_nulls_value(n) != (hash & (n_buckets - 1))))
 440                 goto again;
 441
 442         return NULL;
 443 }
 444
 445 /* Called from syscall or from eBPF program directly, so
 446  * arguments have to match bpf_map_lookup_elem() exactly.
 447  * The return value is adjusted by BPF instructions
 448  * in htab_map_gen_lookup().
 449  */
 450 static void *__htab_map_lookup_elem(struct bpf_map *map, void *key)
 451 {
 452         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
 453         struct hlist_nulls_head *head;
 454         struct htab_elem *l;
 455         u32 hash, key_size;
 456
 457         /* Must be called with rcu_read_lock. */
 458         WARN_ON_ONCE(!rcu_read_lock_held());
 459
 460         key_size = map->key_size;
 461
 462         hash = htab_map_hash(key, key_size);
 463
 464         head = select_bucket(htab, hash);
 465
 466         l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);
 467
 468         return l;
 469 }
 470
 471 static void *htab_map_lookup_elem(struct bpf_map *map, void *key)
 472 {
 473         struct htab_elem *l = __htab_map_lookup_elem(map, key);
 474
 475         if (l)
 476                 return l->key + round_up(map->key_size, 8);
 477
 478         return NULL;
 479 }
 480
 481 /* inline bpf_map_lookup_elem() call.
 482  * Instead of:
 483  * bpf_prog
 484  *   bpf_map_lookup_elem
 485  *     map->ops->map_lookup_elem
 486  *       htab_map_lookup_elem
 487  *         __htab_map_lookup_elem
 488  * do:
 489  * bpf_prog
 490  *   __htab_map_lookup_elem
 491  */
 492 static u32 htab_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
 493 {
 494         struct bpf_insn *insn = insn_buf;
 495         const int ret = BPF_REG_0;
 496
 497         *insn++ = BPF_EMIT_CALL((u64 (*)(u64, u64, u64, u64, u64))__htab_map_lookup_elem);
 498         *insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 1);
 499         *insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
 500                                 offsetof(struct htab_elem, key) +
 501                                 round_up(map->key_size, 8));
 502         return insn - insn_buf;
 503 }
 504
 505 static void *htab_lru_map_lookup_elem(struct bpf_map *map, void *key)
 506 {
 507         struct htab_elem *l = __htab_map_lookup_elem(map, key);
 508
 509         if (l) {
 510                 bpf_lru_node_set_ref(&l->lru_node);
 511                 return l->key + round_up(map->key_size, 8);
 512         }
 513
 514         return NULL;
 515 }
 516
 517 static u32 htab_lru_map_gen_lookup(struct bpf_map *map,
 518                                    struct bpf_insn *insn_buf)
 519 {
 520         struct bpf_insn *insn = insn_buf;
 521         const int ret = BPF_REG_0;
 522         const int ref_reg = BPF_REG_1;
 523
 524         *insn++ = BPF_EMIT_CALL((u64 (*)(u64, u64, u64, u64, u64))__htab_map_lookup_elem);
 525         *insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 4);
 526         *insn++ = BPF_LDX_MEM(BPF_B, ref_reg, ret,
 527                               offsetof(struct htab_elem, lru_node) +
 528                               offsetof(struct bpf_lru_node, ref));
 529         *insn++ = BPF_JMP_IMM(BPF_JNE, ref_reg, 0, 1);
 530         *insn++ = BPF_ST_MEM(BPF_B, ret,
 531                              offsetof(struct htab_elem, lru_node) +
 532                              offsetof(struct bpf_lru_node, ref),
 533                              1);
 534         *insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
 535                                 offsetof(struct htab_elem, key) +
 536                                 round_up(map->key_size, 8));
 537         return insn - insn_buf;
 538 }
 539
 540 /* It is called from the bpf_lru_list when the LRU needs to delete
 541  * older elements from the htab.
 542  */
 543 static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node)
 544 {
 545         struct bpf_htab *htab = (struct bpf_htab *)arg;
 546         struct htab_elem *l = NULL, *tgt_l;
 547         struct hlist_nulls_head *head;
 548         struct hlist_nulls_node *n;
 549         unsigned long flags;
 550         struct bucket *b;
 551
 552         tgt_l = container_of(node, struct htab_elem, lru_node);
 553         b = __select_bucket(htab, tgt_l->hash);
 554         head = &b->head;
 555
 556         raw_spin_lock_irqsave(&b->lock, flags);
 557
 558         hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
 559                 if (l == tgt_l) {
 560                         hlist_nulls_del_rcu(&l->hash_node);
 561                         break;
 562                 }
 563
 564         raw_spin_unlock_irqrestore(&b->lock, flags);
 565
 566         return l == tgt_l;
 567 }
 568
 569 /* Called from syscall */
 570 static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
 571 {
 572         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
 573         struct hlist_nulls_head *head;
 574         struct htab_elem *l, *next_l;
 575         u32 hash, key_size;
 576         int i = 0;
 577
 578         WARN_ON_ONCE(!rcu_read_lock_held());
 579
 580         key_size = map->key_size;
 581
 582         if (!key)
 583                 goto find_first_elem;
 584
 585         hash = htab_map_hash(key, key_size);
 586
 587         head = select_bucket(htab, hash);
 588
 589         /* lookup the key */
 590         l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);
 591
 592         if (!l)
 593                 goto find_first_elem;
 594
 595         /* key was found, get next key in the same bucket */
 596         next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_next_rcu(&l->hash_node)),
 597                                   struct htab_elem, hash_node);
 598
 599         if (next_l) {
 600                 /* if next elem in this hash list is non-zero, just return it */
 601                 memcpy(next_key, next_l->key, key_size);
 602                 return 0;
 603         }
 604
 605         /* no more elements in this hash list, go to the next bucket */
 606         i = hash & (htab->n_buckets - 1);
 607         i++;
 608
 609 find_first_elem:
 610         /* iterate over buckets */
 611         for (; i < htab->n_buckets; i++) {
 612                 head = select_bucket(htab, i);
 613
 614                 /* pick first element in the bucket */
 615                 next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_first_rcu(head)),
 616                                           struct htab_elem, hash_node);
 617                 if (next_l) {
 618                         /* if it's not empty, just return it */
 619                         memcpy(next_key, next_l->key, key_size);
 620                         return 0;
 621                 }
 622         }
 623
 624         /* iterated over all buckets and all elements */
 625         return -ENOENT;
 626 }
 627
 628 static void htab_elem_free(struct bpf_htab *htab, struct htab_elem *l)
 629 {
 630         if (htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH)
 631                 free_percpu(htab_elem_get_ptr(l, htab->map.key_size));
 632         kfree(l);
 633 }
 634
 635 static void htab_elem_free_rcu(struct rcu_head *head)
 636 {
 637         struct htab_elem *l = container_of(head, struct htab_elem, rcu);
 638         struct bpf_htab *htab = l->htab;
 639
 640         /* must increment bpf_prog_active to avoid kprobe+bpf triggering while
 641          * we're calling kfree, otherwise deadlock is possible if kprobes
 642          * are placed somewhere inside of slub
 643          */
 644         preempt_disable();
 645         __this_cpu_inc(bpf_prog_active);
 646         htab_elem_free(htab, l);
 647         __this_cpu_dec(bpf_prog_active);
 648         preempt_enable();
 649 }
 650
 651 static void free_htab_elem(struct bpf_htab *htab, struct htab_elem *l)
 652 {
 653         struct bpf_map *map = &htab->map;
 654
 655         if (map->ops->map_fd_put_ptr) {
 656                 void *ptr = fd_htab_map_get_ptr(map, l);
 657
 658                 map->ops->map_fd_put_ptr(ptr);
 659         }
 660
 661         if (htab_is_prealloc(htab)) {
 662                 pcpu_freelist_push(&htab->freelist, &l->fnode);
 663         } else {
 664                 atomic_dec(&htab->count);
 665                 l->htab = htab;
 666                 call_rcu(&l->rcu, htab_elem_free_rcu);
 667         }
 668 }
 669
 670 static void pcpu_copy_value(struct bpf_htab *htab, void __percpu *pptr,
 671                             void *value, bool onallcpus)
 672 {
 673         if (!onallcpus) {
 674                 /* copy true value_size bytes */
 675                 memcpy(this_cpu_ptr(pptr), value, htab->map.value_size);
 676         } else {
 677                 u32 size = round_up(htab->map.value_size, 8);
 678                 int off = 0, cpu;
 679
 680                 for_each_possible_cpu(cpu) {
 681                         bpf_long_memcpy(per_cpu_ptr(pptr, cpu),
 682                                         value + off, size);
 683                         off += size;
 684                 }
 685         }
 686 }
 687
 688 static bool fd_htab_map_needs_adjust(const struct bpf_htab *htab)
 689 {
 690         return htab->map.map_type == BPF_MAP_TYPE_HASH_OF_MAPS &&
 691                BITS_PER_LONG == 64;
 692 }
 693
 694 static u32 htab_size_value(const struct bpf_htab *htab, bool percpu)
 695 {
 696         u32 size = htab->map.value_size;
 697
 698         if (percpu || fd_htab_map_needs_adjust(htab))
 699                 size = round_up(size, 8);
 700         return size;
 701 }
 702
 703 static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
 704                                          void *value, u32 key_size, u32 hash,
 705                                          bool percpu, bool onallcpus,
 706                                          struct htab_elem *old_elem)
 707 {
 708         u32 size = htab_size_value(htab, percpu);
 709         bool prealloc = htab_is_prealloc(htab);
 710         struct htab_elem *l_new, **pl_new;
 711         void __percpu *pptr;
 712
 713         if (prealloc) {
 714                 if (old_elem) {
 715                         /* if we're updating the existing element,
 716                          * use per-cpu extra elems to avoid freelist_pop/push
 717                          */
 718                         pl_new = this_cpu_ptr(htab->extra_elems);
 719                         l_new = *pl_new;
 720                         *pl_new = old_elem;
 721                 } else {
 722                         struct pcpu_freelist_node *l;
 723
 724                         l = pcpu_freelist_pop(&htab->freelist);
 725                         if (!l)
 726                                 return ERR_PTR(-E2BIG);
 727                         l_new = container_of(l, struct htab_elem, fnode);
 728                 }
 729         } else {
 730                 if (atomic_inc_return(&htab->count) > htab->map.max_entries)
 731                         if (!old_elem) {
 732                                 /* when map is full and update() is replacing
 733                                  * old element, it's ok to allocate, since
 734                                  * old element will be freed immediately.
 735                                  * Otherwise return an error
 736                                  */
 737                                 atomic_dec(&htab->count);
 738                                 return ERR_PTR(-E2BIG);
 739                         }
 740                 l_new = kmalloc_node(htab->elem_size, GFP_ATOMIC | __GFP_NOWARN,
 741                                      htab->map.numa_node);
 742                 if (!l_new)
 743                         return ERR_PTR(-ENOMEM);
 744         }
 745
 746         memcpy(l_new->key, key, key_size);
 747         if (percpu) {
 748                 if (prealloc) {
 749                         pptr = htab_elem_get_ptr(l_new, key_size);
 750                 } else {
 751                         /* alloc_percpu zero-fills */
 752                         pptr = __alloc_percpu_gfp(size, 8,
 753                                                   GFP_ATOMIC | __GFP_NOWARN);
 754                         if (!pptr) {
 755                                 kfree(l_new);
 756                                 return ERR_PTR(-ENOMEM);
 757                         }
 758                 }
 759
 760                 pcpu_copy_value(htab, pptr, value, onallcpus);
 761
 762                 if (!prealloc)
 763                         htab_elem_set_ptr(l_new, key_size, pptr);
 764         } else {
 765                 memcpy(l_new->key + round_up(key_size, 8), value, size);
 766         }
 767
 768         l_new->hash = hash;
 769         return l_new;
 770 }
 771
 772 static int check_flags(struct bpf_htab *htab, struct htab_elem *l_old,
 773                        u64 map_flags)
 774 {
 775         if (l_old && map_flags == BPF_NOEXIST)
 776                 /* elem already exists */
 777                 return -EEXIST;
 778
 779         if (!l_old && map_flags == BPF_EXIST)
 780                 /* elem doesn't exist, cannot update it */
 781                 return -ENOENT;
 782
 783         return 0;
 784 }
 785
 786 /* Called from syscall or from eBPF program */
 787 static int htab_map_update_elem(struct bpf_map *map, void *key, void *value,
 788                                 u64 map_flags)
 789 {
 790         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
 791         struct htab_elem *l_new = NULL, *l_old;
 792         struct hlist_nulls_head *head;
 793         unsigned long flags;
 794         struct bucket *b;
 795         u32 key_size, hash;
 796         int ret;
 797
 798         if (unlikely(map_flags > BPF_EXIST))
 799                 /* unknown flags */
 800                 return -EINVAL;
 801
 802         WARN_ON_ONCE(!rcu_read_lock_held());
 803
 804         key_size = map->key_size;
 805
 806         hash = htab_map_hash(key, key_size);
 807
 808         b = __select_bucket(htab, hash);
 809         head = &b->head;
 810
 811         /* bpf_map_update_elem() can be called in_irq() */
 812         raw_spin_lock_irqsave(&b->lock, flags);
 813
 814         l_old = lookup_elem_raw(head, hash, key, key_size);
 815
 816         ret = check_flags(htab, l_old, map_flags);
 817         if (ret)
 818                 goto err;
 819
 820         l_new = alloc_htab_elem(htab, key, value, key_size, hash, false, false,
 821                                 l_old);
 822         if (IS_ERR(l_new)) {
 823                 /* all pre-allocated elements are in use or memory exhausted */
 824                 ret = PTR_ERR(l_new);
 825                 goto err;
 826         }
 827
 828         /* add new element to the head of the list, so that
 829          * concurrent search will find it before old elem
 830          */
 831         hlist_nulls_add_head_rcu(&l_new->hash_node, head);
 832         if (l_old) {
 833                 hlist_nulls_del_rcu(&l_old->hash_node);
 834                 if (!htab_is_prealloc(htab))
 835                         free_htab_elem(htab, l_old);
 836         }
 837         ret = 0;
 838 err:
 839         raw_spin_unlock_irqrestore(&b->lock, flags);
 840         return ret;
 841 }
 842
 843 static int htab_lru_map_update_elem(struct bpf_map *map, void *key, void *value,
 844                                     u64 map_flags)
 845 {
 846         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
 847         struct htab_elem *l_new, *l_old = NULL;
 848         struct hlist_nulls_head *head;
 849         unsigned long flags;
 850         struct bucket *b;
 851         u32 key_size, hash;
 852         int ret;
 853
 854         if (unlikely(map_flags > BPF_EXIST))
 855                 /* unknown flags */
 856                 return -EINVAL;
 857
 858         WARN_ON_ONCE(!rcu_read_lock_held());
 859
 860         key_size = map->key_size;
 861
 862         hash = htab_map_hash(key, key_size);
 863
 864         b = __select_bucket(htab, hash);
 865         head = &b->head;
 866
 867         /* For LRU, we need to alloc before taking bucket's
 868          * spinlock because getting free nodes from LRU may need
 869          * to remove older elements from htab and this removal
 870          * operation will need a bucket lock.
 871          */
 872         l_new = prealloc_lru_pop(htab, key, hash);
 873         if (!l_new)
 874                 return -ENOMEM;
 875         memcpy(l_new->key + round_up(map->key_size, 8), value, map->value_size);
 876
 877         /* bpf_map_update_elem() can be called in_irq() */
 878         raw_spin_lock_irqsave(&b->lock, flags);
 879
 880         l_old = lookup_elem_raw(head, hash, key, key_size);
 881
 882         ret = check_flags(htab, l_old, map_flags);
 883         if (ret)
 884                 goto err;
 885
 886         /* add new element to the head of the list, so that
 887          * concurrent search will find it before old elem
 888          */
 889         hlist_nulls_add_head_rcu(&l_new->hash_node, head);
 890         if (l_old) {
 891                 bpf_lru_node_set_ref(&l_new->lru_node);
 892                 hlist_nulls_del_rcu(&l_old->hash_node);
 893         }
 894         ret = 0;
 895
 896 err:
 897         raw_spin_unlock_irqrestore(&b->lock, flags);
 898
 899         if (ret)
 900                 bpf_lru_push_free(&htab->lru, &l_new->lru_node);
 901         else if (l_old)
 902                 bpf_lru_push_free(&htab->lru, &l_old->lru_node);
 903
 904         return ret;
 905 }
 906
 907 static int __htab_percpu_map_update_elem(struct bpf_map *map, void *key,
 908                                          void *value, u64 map_flags,
 909                                          bool onallcpus)
 910 {
 911         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
 912         struct htab_elem *l_new = NULL, *l_old;
 913         struct hlist_nulls_head *head;
 914         unsigned long flags;
 915         struct bucket *b;
 916         u32 key_size, hash;
 917         int ret;
 918
 919         if (unlikely(map_flags > BPF_EXIST))
 920                 /* unknown flags */
 921                 return -EINVAL;
 922
 923         WARN_ON_ONCE(!rcu_read_lock_held());
 924
 925         key_size = map->key_size;
 926
 927         hash = htab_map_hash(key, key_size);
 928
 929         b = __select_bucket(htab, hash);
 930         head = &b->head;
 931
 932         /* bpf_map_update_elem() can be called in_irq() */
 933         raw_spin_lock_irqsave(&b->lock, flags);
 934
 935         l_old = lookup_elem_raw(head, hash, key, key_size);
 936
 937         ret = check_flags(htab, l_old, map_flags);
 938         if (ret)
 939                 goto err;
 940
 941         if (l_old) {
 942                 /* per-cpu hash map can update value in-place */
 943                 pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),
 944                                 value, onallcpus);
 945         } else {
 946                 l_new = alloc_htab_elem(htab, key, value, key_size,
 947                                         hash, true, onallcpus, NULL);
 948                 if (IS_ERR(l_new)) {
 949                         ret = PTR_ERR(l_new);
 950                         goto err;
 951                 }
 952                 hlist_nulls_add_head_rcu(&l_new->hash_node, head);
 953         }
 954         ret = 0;
 955 err:
 956         raw_spin_unlock_irqrestore(&b->lock, flags);
 957         return ret;
 958 }
 959
 960 static int __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
 961                                              void *value, u64 map_flags,
 962                                              bool onallcpus)
 963 {
 964         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
 965         struct htab_elem *l_new = NULL, *l_old;
 966         struct hlist_nulls_head *head;
 967         unsigned long flags;
 968         struct bucket *b;
 969         u32 key_size, hash;
 970         int ret;
 971
 972         if (unlikely(map_flags > BPF_EXIST))
 973                 /* unknown flags */
 974                 return -EINVAL;
 975
 976         WARN_ON_ONCE(!rcu_read_lock_held());
 977
 978         key_size = map->key_size;
 979
 980         hash = htab_map_hash(key, key_size);
 981
 982         b = __select_bucket(htab, hash);
 983         head = &b->head;
 984
 985         /* For LRU, we need to alloc before taking bucket's
 986          * spinlock because LRU's elem alloc may need
 987          * to remove older elem from htab and this removal
 988          * operation will need a bucket lock.
 989          */
 990         if (map_flags != BPF_EXIST) {
 991                 l_new = prealloc_lru_pop(htab, key, hash);
 992                 if (!l_new)
 993                         return -ENOMEM;
 994         }
 995
 996         /* bpf_map_update_elem() can be called in_irq() */
 997         raw_spin_lock_irqsave(&b->lock, flags);
 998
 999         l_old = lookup_elem_raw(head, hash, key, key_size);
1000
1001         ret = check_flags(htab, l_old, map_flags);
1002         if (ret)
1003                 goto err;
1004
1005         if (l_old) {
1006                 bpf_lru_node_set_ref(&l_old->lru_node);
1007
1008                 /* per-cpu hash map can update value in-place */
1009                 pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),
1010                                 value, onallcpus);
1011         } else {
1012                 pcpu_copy_value(htab, htab_elem_get_ptr(l_new, key_size),
1013                                 value, onallcpus);
1014                 hlist_nulls_add_head_rcu(&l_new->hash_node, head);
1015                 l_new = NULL;
1016         }
1017         ret = 0;
1018 err:
1019         raw_spin_unlock_irqrestore(&b->lock, flags);
1020         if (l_new)
1021                 bpf_lru_push_free(&htab->lru, &l_new->lru_node);
1022         return ret;
1023 }
1024
1025 static int htab_percpu_map_update_elem(struct bpf_map *map, void *key,
1026                                        void *value, u64 map_flags)
1027 {
1028         return __htab_percpu_map_update_elem(map, key, value, map_flags, false);
1029 }
1030
1031 static int htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
1032                                            void *value, u64 map_flags)
1033 {
1034         return __htab_lru_percpu_map_update_elem(map, key, value, map_flags,
1035                                                  false);
1036 }
1037
1038 /* Called from syscall or from eBPF program */
1039 static int htab_map_delete_elem(struct bpf_map *map, void *key)
1040 {
1041         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1042         struct hlist_nulls_head *head;
1043         struct bucket *b;
1044         struct htab_elem *l;
1045         unsigned long flags;
1046         u32 hash, key_size;
1047         int ret = -ENOENT;
1048
1049         WARN_ON_ONCE(!rcu_read_lock_held());
1050
1051         key_size = map->key_size;
1052
1053         hash = htab_map_hash(key, key_size);
1054         b = __select_bucket(htab, hash);
1055         head = &b->head;
1056
1057         raw_spin_lock_irqsave(&b->lock, flags);
1058
1059         l = lookup_elem_raw(head, hash, key, key_size);
1060
1061         if (l) {
1062                 hlist_nulls_del_rcu(&l->hash_node);
1063                 free_htab_elem(htab, l);
1064                 ret = 0;
1065         }
1066
1067         raw_spin_unlock_irqrestore(&b->lock, flags);
1068         return ret;
1069 }
1070
1071 static int htab_lru_map_delete_elem(struct bpf_map *map, void *key)
1072 {
1073         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1074         struct hlist_nulls_head *head;
1075         struct bucket *b;
1076         struct htab_elem *l;
1077         unsigned long flags;
1078         u32 hash, key_size;
1079         int ret = -ENOENT;
1080
1081         WARN_ON_ONCE(!rcu_read_lock_held());
1082
1083         key_size = map->key_size;
1084
1085         hash = htab_map_hash(key, key_size);
1086         b = __select_bucket(htab, hash);
1087         head = &b->head;
1088
1089         raw_spin_lock_irqsave(&b->lock, flags);
1090
1091         l = lookup_elem_raw(head, hash, key, key_size);
1092
1093         if (l) {
1094                 hlist_nulls_del_rcu(&l->hash_node);
1095                 ret = 0;
1096         }
1097
1098         raw_spin_unlock_irqrestore(&b->lock, flags);
1099         if (l)
1100                 bpf_lru_push_free(&htab->lru, &l->lru_node);
1101         return ret;
1102 }
1103
1104 static void delete_all_elements(struct bpf_htab *htab)
1105 {
1106         int i;
1107
1108         for (i = 0; i < htab->n_buckets; i++) {
1109                 struct hlist_nulls_head *head = select_bucket(htab, i);
1110                 struct hlist_nulls_node *n;
1111                 struct htab_elem *l;
1112
1113                 hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
1114                         hlist_nulls_del_rcu(&l->hash_node);
1115                         htab_elem_free(htab, l);
1116                 }
1117         }
1118 }
1119
1120 /* Called when map->refcnt goes to zero, either from workqueue or from syscall */
1121 static void htab_map_free(struct bpf_map *map)
1122 {
1123         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1124
1125         /* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
1126          * so the programs (can be more than one that used this map) were
1127          * disconnected from events. Wait for outstanding critical sections in
1128          * these programs to complete
1129          */
1130         synchronize_rcu();
1131
1132         /* some of free_htab_elem() callbacks for elements of this map may
1133          * not have executed. Wait for them.
1134          */
1135         rcu_barrier();
1136         if (!htab_is_prealloc(htab))
1137                 delete_all_elements(htab);
1138         else
1139                 prealloc_destroy(htab);
1140
1141         free_percpu(htab->extra_elems);
1142         bpf_map_area_free(htab->buckets);
1143         kfree(htab);
1144 }
1145
1146 const struct bpf_map_ops htab_map_ops = {
1147         .map_alloc = htab_map_alloc,
1148         .map_free = htab_map_free,
1149         .map_get_next_key = htab_map_get_next_key,
1150         .map_lookup_elem = htab_map_lookup_elem,
1151         .map_update_elem = htab_map_update_elem,
1152         .map_delete_elem = htab_map_delete_elem,
1153         .map_gen_lookup = htab_map_gen_lookup,
1154 };
1155
1156 const struct bpf_map_ops htab_lru_map_ops = {
1157         .map_alloc = htab_map_alloc,
1158         .map_free = htab_map_free,
1159         .map_get_next_key = htab_map_get_next_key,
1160         .map_lookup_elem = htab_lru_map_lookup_elem,
1161         .map_update_elem = htab_lru_map_update_elem,
1162         .map_delete_elem = htab_lru_map_delete_elem,
1163         .map_gen_lookup = htab_lru_map_gen_lookup,
1164 };
1165
1166 /* Called from eBPF program */
1167 static void *htab_percpu_map_lookup_elem(struct bpf_map *map, void *key)
1168 {
1169         struct htab_elem *l = __htab_map_lookup_elem(map, key);
1170
1171         if (l)
1172                 return this_cpu_ptr(htab_elem_get_ptr(l, map->key_size));
1173         else
1174                 return NULL;
1175 }
1176
1177 static void *htab_lru_percpu_map_lookup_elem(struct bpf_map *map, void *key)
1178 {
1179         struct htab_elem *l = __htab_map_lookup_elem(map, key);
1180
1181         if (l) {
1182                 bpf_lru_node_set_ref(&l->lru_node);
1183                 return this_cpu_ptr(htab_elem_get_ptr(l, map->key_size));
1184         }
1185
1186         return NULL;
1187 }
1188
1189 int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value)
1190 {
1191         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1192         struct htab_elem *l;
1193         void __percpu *pptr;
1194         int ret = -ENOENT;
1195         int cpu, off = 0;
1196         u32 size;
1197
1198         /* per_cpu areas are zero-filled and bpf programs can only
1199          * access 'value_size' of them, so copying rounded areas
1200          * will not leak any kernel data
1201          */
1202         size = round_up(map->value_size, 8);
1203         rcu_read_lock();
1204         l = __htab_map_lookup_elem(map, key);
1205         if (!l)
1206                 goto out;
1207         if (htab_is_lru(htab))
1208                 bpf_lru_node_set_ref(&l->lru_node);
1209         pptr = htab_elem_get_ptr(l, map->key_size);
1210         for_each_possible_cpu(cpu) {
1211                 bpf_long_memcpy(value + off,
1212                                 per_cpu_ptr(pptr, cpu), size);
1213                 off += size;
1214         }
1215         ret = 0;
1216 out:
1217         rcu_read_unlock();
1218         return ret;
1219 }
1220
1221 int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value,
1222                            u64 map_flags)
1223 {
1224         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1225         int ret;
1226
1227         rcu_read_lock();
1228         if (htab_is_lru(htab))
1229                 ret = __htab_lru_percpu_map_update_elem(map, key, value,
1230                                                         map_flags, true);
1231         else
1232                 ret = __htab_percpu_map_update_elem(map, key, value, map_flags,
1233                                                     true);
1234         rcu_read_unlock();
1235
1236         return ret;
1237 }
1238
1239 const struct bpf_map_ops htab_percpu_map_ops = {
1240         .map_alloc = htab_map_alloc,
1241         .map_free = htab_map_free,
1242         .map_get_next_key = htab_map_get_next_key,
1243         .map_lookup_elem = htab_percpu_map_lookup_elem,
1244         .map_update_elem = htab_percpu_map_update_elem,
1245         .map_delete_elem = htab_map_delete_elem,
1246 };
1247
1248 const struct bpf_map_ops htab_lru_percpu_map_ops = {
1249         .map_alloc = htab_map_alloc,
1250         .map_free = htab_map_free,
1251         .map_get_next_key = htab_map_get_next_key,
1252         .map_lookup_elem = htab_lru_percpu_map_lookup_elem,
1253         .map_update_elem = htab_lru_percpu_map_update_elem,
1254         .map_delete_elem = htab_lru_map_delete_elem,
1255 };
1256
1257 static struct bpf_map *fd_htab_map_alloc(union bpf_attr *attr)
1258 {
1259         if (attr->value_size != sizeof(u32))
1260                 return ERR_PTR(-EINVAL);
1261         return htab_map_alloc(attr);
1262 }
1263
1264 static void fd_htab_map_free(struct bpf_map *map)
1265 {
1266         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1267         struct hlist_nulls_node *n;
1268         struct hlist_nulls_head *head;
1269         struct htab_elem *l;
1270         int i;
1271
1272         for (i = 0; i < htab->n_buckets; i++) {
1273                 head = select_bucket(htab, i);
1274
1275                 hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
1276                         void *ptr = fd_htab_map_get_ptr(map, l);
1277
1278                         map->ops->map_fd_put_ptr(ptr);
1279                 }
1280         }
1281
1282         htab_map_free(map);
1283 }
1284
1285 /* only called from syscall */
1286 int bpf_fd_htab_map_lookup_elem(struct bpf_map *map, void *key, u32 *value)
1287 {
1288         void **ptr;
1289         int ret = 0;
1290
1291         if (!map->ops->map_fd_sys_lookup_elem)
1292                 return -ENOTSUPP;
1293
1294         rcu_read_lock();
1295         ptr = htab_map_lookup_elem(map, key);
1296         if (ptr)
1297                 *value = map->ops->map_fd_sys_lookup_elem(READ_ONCE(*ptr));
1298         else
1299                 ret = -ENOENT;
1300         rcu_read_unlock();
1301
1302         return ret;
1303 }
1304
1305 /* only called from syscall */
1306 int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file,
1307                                 void *key, void *value, u64 map_flags)
1308 {
1309         void *ptr;
1310         int ret;
1311         u32 ufd = *(u32 *)value;
1312
1313         ptr = map->ops->map_fd_get_ptr(map, map_file, ufd);
1314         if (IS_ERR(ptr))
1315                 return PTR_ERR(ptr);
1316
1317         ret = htab_map_update_elem(map, key, &ptr, map_flags);
1318         if (ret)
1319                 map->ops->map_fd_put_ptr(ptr);
1320
1321         return ret;
1322 }
1323
1324 static struct bpf_map *htab_of_map_alloc(union bpf_attr *attr)
1325 {
1326         struct bpf_map *map, *inner_map_meta;
1327
1328         inner_map_meta = bpf_map_meta_alloc(attr->inner_map_fd);
1329         if (IS_ERR(inner_map_meta))
1330                 return inner_map_meta;
1331
1332         map = fd_htab_map_alloc(attr);
1333         if (IS_ERR(map)) {
1334                 bpf_map_meta_free(inner_map_meta);
1335                 return map;
1336         }
1337
1338         map->inner_map_meta = inner_map_meta;
1339
1340         return map;
1341 }
1342
1343 static void *htab_of_map_lookup_elem(struct bpf_map *map, void *key)
1344 {
1345         struct bpf_map **inner_map  = htab_map_lookup_elem(map, key);
1346
1347         if (!inner_map)
1348                 return NULL;
1349
1350         return READ_ONCE(*inner_map);
1351 }
1352
1353 static u32 htab_of_map_gen_lookup(struct bpf_map *map,
1354                                   struct bpf_insn *insn_buf)
1355 {
1356         struct bpf_insn *insn = insn_buf;
1357         const int ret = BPF_REG_0;
1358
1359         *insn++ = BPF_EMIT_CALL((u64 (*)(u64, u64, u64, u64, u64))__htab_map_lookup_elem);
1360         *insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 2);
1361         *insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
1362                                 offsetof(struct htab_elem, key) +
1363                                 round_up(map->key_size, 8));
1364         *insn++ = BPF_LDX_MEM(BPF_DW, ret, ret, 0);
1365
1366         return insn - insn_buf;
1367 }
1368
1369 static void htab_of_map_free(struct bpf_map *map)
1370 {
1371         bpf_map_meta_free(map->inner_map_meta);
1372         fd_htab_map_free(map);
1373 }
1374
1375 const struct bpf_map_ops htab_of_maps_map_ops = {
1376         .map_alloc = htab_of_map_alloc,
1377         .map_free = htab_of_map_free,
1378         .map_get_next_key = htab_map_get_next_key,
1379         .map_lookup_elem = htab_of_map_lookup_elem,
1380         .map_delete_elem = htab_map_delete_elem,
1381         .map_fd_get_ptr = bpf_map_fd_get_ptr,
1382         .map_fd_put_ptr = bpf_map_fd_put_ptr,
1383         .map_fd_sys_lookup_elem = bpf_map_fd_sys_lookup_elem,
1384         .map_gen_lookup = htab_of_map_gen_lookup,
1385 };