kernel/bpf/bpf_local_storage.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (c) 2019 Facebook  */
   3 #include <linux/rculist.h>
   4 #include <linux/list.h>
   5 #include <linux/hash.h>
   6 #include <linux/types.h>
   7 #include <linux/spinlock.h>
   8 #include <linux/bpf.h>
   9 #include <linux/btf_ids.h>
  10 #include <linux/bpf_local_storage.h>
  11 #include <net/sock.h>
  12 #include <uapi/linux/sock_diag.h>
  13 #include <uapi/linux/btf.h>
  14 #include <linux/rcupdate.h>
  15 #include <linux/rcupdate_trace.h>
  16 #include <linux/rcupdate_wait.h>
  17
  18 #define BPF_LOCAL_STORAGE_CREATE_FLAG_MASK (BPF_F_NO_PREALLOC | BPF_F_CLONE)
  19
  20 static struct bpf_local_storage_map_bucket *
  21 select_bucket(struct bpf_local_storage_map *smap,
  22               struct bpf_local_storage_elem *selem)
  23 {
  24         return &smap->buckets[hash_ptr(selem, smap->bucket_log)];
  25 }
  26
  27 static int mem_charge(struct bpf_local_storage_map *smap, void *owner, u32 size)
  28 {
  29         struct bpf_map *map = &smap->map;
  30
  31         if (!map->ops->map_local_storage_charge)
  32                 return 0;
  33
  34         return map->ops->map_local_storage_charge(smap, owner, size);
  35 }
  36
  37 static void mem_uncharge(struct bpf_local_storage_map *smap, void *owner,
  38                          u32 size)
  39 {
  40         struct bpf_map *map = &smap->map;
  41
  42         if (map->ops->map_local_storage_uncharge)
  43                 map->ops->map_local_storage_uncharge(smap, owner, size);
  44 }
  45
  46 static struct bpf_local_storage __rcu **
  47 owner_storage(struct bpf_local_storage_map *smap, void *owner)
  48 {
  49         struct bpf_map *map = &smap->map;
  50
  51         return map->ops->map_owner_storage_ptr(owner);
  52 }
  53
  54 static bool selem_linked_to_storage(const struct bpf_local_storage_elem *selem)
  55 {
  56         return !hlist_unhashed(&selem->snode);
  57 }
  58
  59 static bool selem_linked_to_map(const struct bpf_local_storage_elem *selem)
  60 {
  61         return !hlist_unhashed(&selem->map_node);
  62 }
  63
  64 struct bpf_local_storage_elem *
  65 bpf_selem_alloc(struct bpf_local_storage_map *smap, void *owner,
  66                 void *value, bool charge_mem, gfp_t gfp_flags)
  67 {
  68         struct bpf_local_storage_elem *selem;
  69
  70         if (charge_mem && mem_charge(smap, owner, smap->elem_size))
  71                 return NULL;
  72
  73         selem = bpf_map_kzalloc(&smap->map, smap->elem_size,
  74                                 gfp_flags | __GFP_NOWARN);
  75         if (selem) {
  76                 if (value)
  77                         memcpy(SDATA(selem)->data, value, smap->map.value_size);
  78                 return selem;
  79         }
  80
  81         if (charge_mem)
  82                 mem_uncharge(smap, owner, smap->elem_size);
  83
  84         return NULL;
  85 }
  86
  87 void bpf_local_storage_free_rcu(struct rcu_head *rcu)
  88 {
  89         struct bpf_local_storage *local_storage;
  90
  91         local_storage = container_of(rcu, struct bpf_local_storage, rcu);
  92         kfree_rcu(local_storage, rcu);
  93 }
  94
  95 static void bpf_selem_free_rcu(struct rcu_head *rcu)
  96 {
  97         struct bpf_local_storage_elem *selem;
  98
  99         selem = container_of(rcu, struct bpf_local_storage_elem, rcu);
 100         kfree_rcu(selem, rcu);
 101 }
 102
 103 /* local_storage->lock must be held and selem->local_storage == local_storage.
 104  * The caller must ensure selem->smap is still valid to be
 105  * dereferenced for its smap->elem_size and smap->cache_idx.
 106  */
 107 bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_storage,
 108                                      struct bpf_local_storage_elem *selem,
 109                                      bool uncharge_mem, bool use_trace_rcu)
 110 {
 111         struct bpf_local_storage_map *smap;
 112         bool free_local_storage;
 113         void *owner;
 114
 115         smap = rcu_dereference_check(SDATA(selem)->smap, bpf_rcu_lock_held());
 116         owner = local_storage->owner;
 117
 118         /* All uncharging on the owner must be done first.
 119          * The owner may be freed once the last selem is unlinked
 120          * from local_storage.
 121          */
 122         if (uncharge_mem)
 123                 mem_uncharge(smap, owner, smap->elem_size);
 124
 125         free_local_storage = hlist_is_singular_node(&selem->snode,
 126                                                     &local_storage->list);
 127         if (free_local_storage) {
 128                 mem_uncharge(smap, owner, sizeof(struct bpf_local_storage));
 129                 local_storage->owner = NULL;
 130
 131                 /* After this RCU_INIT, owner may be freed and cannot be used */
 132                 RCU_INIT_POINTER(*owner_storage(smap, owner), NULL);
 133
 134                 /* local_storage is not freed now.  local_storage->lock is
 135                  * still held and raw_spin_unlock_bh(&local_storage->lock)
 136                  * will be done by the caller.
 137                  *
 138                  * Although the unlock will be done under
 139                  * rcu_read_lock(),  it is more intuitive to
 140                  * read if the freeing of the storage is done
 141                  * after the raw_spin_unlock_bh(&local_storage->lock).
 142                  *
 143                  * Hence, a "bool free_local_storage" is returned
 144                  * to the caller which then calls then frees the storage after
 145                  * all the RCU grace periods have expired.
 146                  */
 147         }
 148         hlist_del_init_rcu(&selem->snode);
 149         if (rcu_access_pointer(local_storage->cache[smap->cache_idx]) ==
 150             SDATA(selem))
 151                 RCU_INIT_POINTER(local_storage->cache[smap->cache_idx], NULL);
 152
 153         if (use_trace_rcu)
 154                 call_rcu_tasks_trace(&selem->rcu, bpf_selem_free_rcu);
 155         else
 156                 kfree_rcu(selem, rcu);
 157
 158         return free_local_storage;
 159 }
 160
 161 static void __bpf_selem_unlink_storage(struct bpf_local_storage_elem *selem,
 162                                        bool use_trace_rcu)
 163 {
 164         struct bpf_local_storage *local_storage;
 165         bool free_local_storage = false;
 166         unsigned long flags;
 167
 168         if (unlikely(!selem_linked_to_storage(selem)))
 169                 /* selem has already been unlinked from sk */
 170                 return;
 171
 172         local_storage = rcu_dereference_check(selem->local_storage,
 173                                               bpf_rcu_lock_held());
 174         raw_spin_lock_irqsave(&local_storage->lock, flags);
 175         if (likely(selem_linked_to_storage(selem)))
 176                 free_local_storage = bpf_selem_unlink_storage_nolock(
 177                         local_storage, selem, true, use_trace_rcu);
 178         raw_spin_unlock_irqrestore(&local_storage->lock, flags);
 179
 180         if (free_local_storage) {
 181                 if (use_trace_rcu)
 182                         call_rcu_tasks_trace(&local_storage->rcu,
 183                                      bpf_local_storage_free_rcu);
 184                 else
 185                         kfree_rcu(local_storage, rcu);
 186         }
 187 }
 188
 189 void bpf_selem_link_storage_nolock(struct bpf_local_storage *local_storage,
 190                                    struct bpf_local_storage_elem *selem)
 191 {
 192         RCU_INIT_POINTER(selem->local_storage, local_storage);
 193         hlist_add_head_rcu(&selem->snode, &local_storage->list);
 194 }
 195
 196 void bpf_selem_unlink_map(struct bpf_local_storage_elem *selem)
 197 {
 198         struct bpf_local_storage_map *smap;
 199         struct bpf_local_storage_map_bucket *b;
 200         unsigned long flags;
 201
 202         if (unlikely(!selem_linked_to_map(selem)))
 203                 /* selem has already be unlinked from smap */
 204                 return;
 205
 206         smap = rcu_dereference_check(SDATA(selem)->smap, bpf_rcu_lock_held());
 207         b = select_bucket(smap, selem);
 208         raw_spin_lock_irqsave(&b->lock, flags);
 209         if (likely(selem_linked_to_map(selem)))
 210                 hlist_del_init_rcu(&selem->map_node);
 211         raw_spin_unlock_irqrestore(&b->lock, flags);
 212 }
 213
 214 void bpf_selem_link_map(struct bpf_local_storage_map *smap,
 215                         struct bpf_local_storage_elem *selem)
 216 {
 217         struct bpf_local_storage_map_bucket *b = select_bucket(smap, selem);
 218         unsigned long flags;
 219
 220         raw_spin_lock_irqsave(&b->lock, flags);
 221         RCU_INIT_POINTER(SDATA(selem)->smap, smap);
 222         hlist_add_head_rcu(&selem->map_node, &b->list);
 223         raw_spin_unlock_irqrestore(&b->lock, flags);
 224 }
 225
 226 void bpf_selem_unlink(struct bpf_local_storage_elem *selem, bool use_trace_rcu)
 227 {
 228         /* Always unlink from map before unlinking from local_storage
 229          * because selem will be freed after successfully unlinked from
 230          * the local_storage.
 231          */
 232         bpf_selem_unlink_map(selem);
 233         __bpf_selem_unlink_storage(selem, use_trace_rcu);
 234 }
 235
 236 struct bpf_local_storage_data *
 237 bpf_local_storage_lookup(struct bpf_local_storage *local_storage,
 238                          struct bpf_local_storage_map *smap,
 239                          bool cacheit_lockit)
 240 {
 241         struct bpf_local_storage_data *sdata;
 242         struct bpf_local_storage_elem *selem;
 243
 244         /* Fast path (cache hit) */
 245         sdata = rcu_dereference_check(local_storage->cache[smap->cache_idx],
 246                                       bpf_rcu_lock_held());
 247         if (sdata && rcu_access_pointer(sdata->smap) == smap)
 248                 return sdata;
 249
 250         /* Slow path (cache miss) */
 251         hlist_for_each_entry_rcu(selem, &local_storage->list, snode,
 252                                   rcu_read_lock_trace_held())
 253                 if (rcu_access_pointer(SDATA(selem)->smap) == smap)
 254                         break;
 255
 256         if (!selem)
 257                 return NULL;
 258
 259         sdata = SDATA(selem);
 260         if (cacheit_lockit) {
 261                 unsigned long flags;
 262
 263                 /* spinlock is needed to avoid racing with the
 264                  * parallel delete.  Otherwise, publishing an already
 265                  * deleted sdata to the cache will become a use-after-free
 266                  * problem in the next bpf_local_storage_lookup().
 267                  */
 268                 raw_spin_lock_irqsave(&local_storage->lock, flags);
 269                 if (selem_linked_to_storage(selem))
 270                         rcu_assign_pointer(local_storage->cache[smap->cache_idx],
 271                                            sdata);
 272                 raw_spin_unlock_irqrestore(&local_storage->lock, flags);
 273         }
 274
 275         return sdata;
 276 }
 277
 278 static int check_flags(const struct bpf_local_storage_data *old_sdata,
 279                        u64 map_flags)
 280 {
 281         if (old_sdata && (map_flags & ~BPF_F_LOCK) == BPF_NOEXIST)
 282                 /* elem already exists */
 283                 return -EEXIST;
 284
 285         if (!old_sdata && (map_flags & ~BPF_F_LOCK) == BPF_EXIST)
 286                 /* elem doesn't exist, cannot update it */
 287                 return -ENOENT;
 288
 289         return 0;
 290 }
 291
 292 int bpf_local_storage_alloc(void *owner,
 293                             struct bpf_local_storage_map *smap,
 294                             struct bpf_local_storage_elem *first_selem,
 295                             gfp_t gfp_flags)
 296 {
 297         struct bpf_local_storage *prev_storage, *storage;
 298         struct bpf_local_storage **owner_storage_ptr;
 299         int err;
 300
 301         err = mem_charge(smap, owner, sizeof(*storage));
 302         if (err)
 303                 return err;
 304
 305         storage = bpf_map_kzalloc(&smap->map, sizeof(*storage),
 306                                   gfp_flags | __GFP_NOWARN);
 307         if (!storage) {
 308                 err = -ENOMEM;
 309                 goto uncharge;
 310         }
 311
 312         INIT_HLIST_HEAD(&storage->list);
 313         raw_spin_lock_init(&storage->lock);
 314         storage->owner = owner;
 315
 316         bpf_selem_link_storage_nolock(storage, first_selem);
 317         bpf_selem_link_map(smap, first_selem);
 318
 319         owner_storage_ptr =
 320                 (struct bpf_local_storage **)owner_storage(smap, owner);
 321         /* Publish storage to the owner.
 322          * Instead of using any lock of the kernel object (i.e. owner),
 323          * cmpxchg will work with any kernel object regardless what
 324          * the running context is, bh, irq...etc.
 325          *
 326          * From now on, the owner->storage pointer (e.g. sk->sk_bpf_storage)
 327          * is protected by the storage->lock.  Hence, when freeing
 328          * the owner->storage, the storage->lock must be held before
 329          * setting owner->storage ptr to NULL.
 330          */
 331         prev_storage = cmpxchg(owner_storage_ptr, NULL, storage);
 332         if (unlikely(prev_storage)) {
 333                 bpf_selem_unlink_map(first_selem);
 334                 err = -EAGAIN;
 335                 goto uncharge;
 336
 337                 /* Note that even first_selem was linked to smap's
 338                  * bucket->list, first_selem can be freed immediately
 339                  * (instead of kfree_rcu) because
 340                  * bpf_local_storage_map_free() does a
 341                  * synchronize_rcu_mult (waiting for both sleepable and
 342                  * normal programs) before walking the bucket->list.
 343                  * Hence, no one is accessing selem from the
 344                  * bucket->list under rcu_read_lock().
 345                  */
 346         }
 347
 348         return 0;
 349
 350 uncharge:
 351         kfree(storage);
 352         mem_uncharge(smap, owner, sizeof(*storage));
 353         return err;
 354 }
 355
 356 /* sk cannot be going away because it is linking new elem
 357  * to sk->sk_bpf_storage. (i.e. sk->sk_refcnt cannot be 0).
 358  * Otherwise, it will become a leak (and other memory issues
 359  * during map destruction).
 360  */
 361 struct bpf_local_storage_data *
 362 bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap,
 363                          void *value, u64 map_flags, gfp_t gfp_flags)
 364 {
 365         struct bpf_local_storage_data *old_sdata = NULL;
 366         struct bpf_local_storage_elem *selem = NULL;
 367         struct bpf_local_storage *local_storage;
 368         unsigned long flags;
 369         int err;
 370
 371         /* BPF_EXIST and BPF_NOEXIST cannot be both set */
 372         if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST) ||
 373             /* BPF_F_LOCK can only be used in a value with spin_lock */
 374             unlikely((map_flags & BPF_F_LOCK) &&
 375                      !map_value_has_spin_lock(&smap->map)))
 376                 return ERR_PTR(-EINVAL);
 377
 378         if (gfp_flags == GFP_KERNEL && (map_flags & ~BPF_F_LOCK) != BPF_NOEXIST)
 379                 return ERR_PTR(-EINVAL);
 380
 381         local_storage = rcu_dereference_check(*owner_storage(smap, owner),
 382                                               bpf_rcu_lock_held());
 383         if (!local_storage || hlist_empty(&local_storage->list)) {
 384                 /* Very first elem for the owner */
 385                 err = check_flags(NULL, map_flags);
 386                 if (err)
 387                         return ERR_PTR(err);
 388
 389                 selem = bpf_selem_alloc(smap, owner, value, true, gfp_flags);
 390                 if (!selem)
 391                         return ERR_PTR(-ENOMEM);
 392
 393                 err = bpf_local_storage_alloc(owner, smap, selem, gfp_flags);
 394                 if (err) {
 395                         kfree(selem);
 396                         mem_uncharge(smap, owner, smap->elem_size);
 397                         return ERR_PTR(err);
 398                 }
 399
 400                 return SDATA(selem);
 401         }
 402
 403         if ((map_flags & BPF_F_LOCK) && !(map_flags & BPF_NOEXIST)) {
 404                 /* Hoping to find an old_sdata to do inline update
 405                  * such that it can avoid taking the local_storage->lock
 406                  * and changing the lists.
 407                  */
 408                 old_sdata =
 409                         bpf_local_storage_lookup(local_storage, smap, false);
 410                 err = check_flags(old_sdata, map_flags);
 411                 if (err)
 412                         return ERR_PTR(err);
 413                 if (old_sdata && selem_linked_to_storage(SELEM(old_sdata))) {
 414                         copy_map_value_locked(&smap->map, old_sdata->data,
 415                                               value, false);
 416                         return old_sdata;
 417                 }
 418         }
 419
 420         if (gfp_flags == GFP_KERNEL) {
 421                 selem = bpf_selem_alloc(smap, owner, value, true, gfp_flags);
 422                 if (!selem)
 423                         return ERR_PTR(-ENOMEM);
 424         }
 425
 426         raw_spin_lock_irqsave(&local_storage->lock, flags);
 427
 428         /* Recheck local_storage->list under local_storage->lock */
 429         if (unlikely(hlist_empty(&local_storage->list))) {
 430                 /* A parallel del is happening and local_storage is going
 431                  * away.  It has just been checked before, so very
 432                  * unlikely.  Return instead of retry to keep things
 433                  * simple.
 434                  */
 435                 err = -EAGAIN;
 436                 goto unlock_err;
 437         }
 438
 439         old_sdata = bpf_local_storage_lookup(local_storage, smap, false);
 440         err = check_flags(old_sdata, map_flags);
 441         if (err)
 442                 goto unlock_err;
 443
 444         if (old_sdata && (map_flags & BPF_F_LOCK)) {
 445                 copy_map_value_locked(&smap->map, old_sdata->data, value,
 446                                       false);
 447                 selem = SELEM(old_sdata);
 448                 goto unlock;
 449         }
 450
 451         if (gfp_flags != GFP_KERNEL) {
 452                 /* local_storage->lock is held.  Hence, we are sure
 453                  * we can unlink and uncharge the old_sdata successfully
 454                  * later.  Hence, instead of charging the new selem now
 455                  * and then uncharge the old selem later (which may cause
 456                  * a potential but unnecessary charge failure),  avoid taking
 457                  * a charge at all here (the "!old_sdata" check) and the
 458                  * old_sdata will not be uncharged later during
 459                  * bpf_selem_unlink_storage_nolock().
 460                  */
 461                 selem = bpf_selem_alloc(smap, owner, value, !old_sdata, gfp_flags);
 462                 if (!selem) {
 463                         err = -ENOMEM;
 464                         goto unlock_err;
 465                 }
 466         }
 467
 468         /* First, link the new selem to the map */
 469         bpf_selem_link_map(smap, selem);
 470
 471         /* Second, link (and publish) the new selem to local_storage */
 472         bpf_selem_link_storage_nolock(local_storage, selem);
 473
 474         /* Third, remove old selem, SELEM(old_sdata) */
 475         if (old_sdata) {
 476                 bpf_selem_unlink_map(SELEM(old_sdata));
 477                 bpf_selem_unlink_storage_nolock(local_storage, SELEM(old_sdata),
 478                                                 false, true);
 479         }
 480
 481 unlock:
 482         raw_spin_unlock_irqrestore(&local_storage->lock, flags);
 483         return SDATA(selem);
 484
 485 unlock_err:
 486         raw_spin_unlock_irqrestore(&local_storage->lock, flags);
 487         if (selem) {
 488                 mem_uncharge(smap, owner, smap->elem_size);
 489                 kfree(selem);
 490         }
 491         return ERR_PTR(err);
 492 }
 493
 494 u16 bpf_local_storage_cache_idx_get(struct bpf_local_storage_cache *cache)
 495 {
 496         u64 min_usage = U64_MAX;
 497         u16 i, res = 0;
 498
 499         spin_lock(&cache->idx_lock);
 500
 501         for (i = 0; i < BPF_LOCAL_STORAGE_CACHE_SIZE; i++) {
 502                 if (cache->idx_usage_counts[i] < min_usage) {
 503                         min_usage = cache->idx_usage_counts[i];
 504                         res = i;
 505
 506                         /* Found a free cache_idx */
 507                         if (!min_usage)
 508                                 break;
 509                 }
 510         }
 511         cache->idx_usage_counts[res]++;
 512
 513         spin_unlock(&cache->idx_lock);
 514
 515         return res;
 516 }
 517
 518 void bpf_local_storage_cache_idx_free(struct bpf_local_storage_cache *cache,
 519                                       u16 idx)
 520 {
 521         spin_lock(&cache->idx_lock);
 522         cache->idx_usage_counts[idx]--;
 523         spin_unlock(&cache->idx_lock);
 524 }
 525
 526 void bpf_local_storage_map_free(struct bpf_local_storage_map *smap,
 527                                 int __percpu *busy_counter)
 528 {
 529         struct bpf_local_storage_elem *selem;
 530         struct bpf_local_storage_map_bucket *b;
 531         unsigned int i;
 532
 533         /* Note that this map might be concurrently cloned from
 534          * bpf_sk_storage_clone. Wait for any existing bpf_sk_storage_clone
 535          * RCU read section to finish before proceeding. New RCU
 536          * read sections should be prevented via bpf_map_inc_not_zero.
 537          */
 538         synchronize_rcu();
 539
 540         /* bpf prog and the userspace can no longer access this map
 541          * now.  No new selem (of this map) can be added
 542          * to the owner->storage or to the map bucket's list.
 543          *
 544          * The elem of this map can be cleaned up here
 545          * or when the storage is freed e.g.
 546          * by bpf_sk_storage_free() during __sk_destruct().
 547          */
 548         for (i = 0; i < (1U << smap->bucket_log); i++) {
 549                 b = &smap->buckets[i];
 550
 551                 rcu_read_lock();
 552                 /* No one is adding to b->list now */
 553                 while ((selem = hlist_entry_safe(
 554                                 rcu_dereference_raw(hlist_first_rcu(&b->list)),
 555                                 struct bpf_local_storage_elem, map_node))) {
 556                         if (busy_counter) {
 557                                 migrate_disable();
 558                                 __this_cpu_inc(*busy_counter);
 559                         }
 560                         bpf_selem_unlink(selem, false);
 561                         if (busy_counter) {
 562                                 __this_cpu_dec(*busy_counter);
 563                                 migrate_enable();
 564                         }
 565                         cond_resched_rcu();
 566                 }
 567                 rcu_read_unlock();
 568         }
 569
 570         /* While freeing the storage we may still need to access the map.
 571          *
 572          * e.g. when bpf_sk_storage_free() has unlinked selem from the map
 573          * which then made the above while((selem = ...)) loop
 574          * exit immediately.
 575          *
 576          * However, while freeing the storage one still needs to access the
 577          * smap->elem_size to do the uncharging in
 578          * bpf_selem_unlink_storage_nolock().
 579          *
 580          * Hence, wait another rcu grace period for the storage to be freed.
 581          */
 582         synchronize_rcu();
 583
 584         kvfree(smap->buckets);
 585         kfree(smap);
 586 }
 587
 588 int bpf_local_storage_map_alloc_check(union bpf_attr *attr)
 589 {
 590         if (attr->map_flags & ~BPF_LOCAL_STORAGE_CREATE_FLAG_MASK ||
 591             !(attr->map_flags & BPF_F_NO_PREALLOC) ||
 592             attr->max_entries ||
 593             attr->key_size != sizeof(int) || !attr->value_size ||
 594             /* Enforce BTF for userspace sk dumping */
 595             !attr->btf_key_type_id || !attr->btf_value_type_id)
 596                 return -EINVAL;
 597
 598         if (!bpf_capable())
 599                 return -EPERM;
 600
 601         if (attr->value_size > BPF_LOCAL_STORAGE_MAX_VALUE_SIZE)
 602                 return -E2BIG;
 603
 604         return 0;
 605 }
 606
 607 struct bpf_local_storage_map *bpf_local_storage_map_alloc(union bpf_attr *attr)
 608 {
 609         struct bpf_local_storage_map *smap;
 610         unsigned int i;
 611         u32 nbuckets;
 612
 613         smap = kzalloc(sizeof(*smap), GFP_USER | __GFP_NOWARN | __GFP_ACCOUNT);
 614         if (!smap)
 615                 return ERR_PTR(-ENOMEM);
 616         bpf_map_init_from_attr(&smap->map, attr);
 617
 618         nbuckets = roundup_pow_of_two(num_possible_cpus());
 619         /* Use at least 2 buckets, select_bucket() is undefined behavior with 1 bucket */
 620         nbuckets = max_t(u32, 2, nbuckets);
 621         smap->bucket_log = ilog2(nbuckets);
 622
 623         smap->buckets = kvcalloc(sizeof(*smap->buckets), nbuckets,
 624                                  GFP_USER | __GFP_NOWARN | __GFP_ACCOUNT);
 625         if (!smap->buckets) {
 626                 kfree(smap);
 627                 return ERR_PTR(-ENOMEM);
 628         }
 629
 630         for (i = 0; i < nbuckets; i++) {
 631                 INIT_HLIST_HEAD(&smap->buckets[i].list);
 632                 raw_spin_lock_init(&smap->buckets[i].lock);
 633         }
 634
 635         smap->elem_size =
 636                 sizeof(struct bpf_local_storage_elem) + attr->value_size;
 637
 638         return smap;
 639 }
 640
 641 int bpf_local_storage_map_check_btf(const struct bpf_map *map,
 642                                     const struct btf *btf,
 643                                     const struct btf_type *key_type,
 644                                     const struct btf_type *value_type)
 645 {
 646         u32 int_data;
 647
 648         if (BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
 649                 return -EINVAL;
 650
 651         int_data = *(u32 *)(key_type + 1);
 652         if (BTF_INT_BITS(int_data) != 32 || BTF_INT_OFFSET(int_data))
 653                 return -EINVAL;
 654
 655         return 0;
 656 }