kernel/bpf/hashtab.c

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This source file includes following definitions.
htab_is_lru
htab_is_percpu
htab_is_prealloc
htab_elem_set_ptr
htab_elem_get_ptr
fd_htab_map_get_ptr
get_htab_elem
htab_free_elems
prealloc_lru_pop
prealloc_init
prealloc_destroy
alloc_extra_elems
htab_map_alloc_check
htab_map_alloc
htab_map_hash
__select_bucket
select_bucket
lookup_elem_raw
lookup_nulls_elem_raw
__htab_map_lookup_elem
htab_map_lookup_elem
htab_map_gen_lookup
__htab_lru_map_lookup_elem
htab_lru_map_lookup_elem
htab_lru_map_lookup_elem_sys
htab_lru_map_gen_lookup
htab_lru_map_delete_node
htab_map_get_next_key
htab_elem_free
htab_elem_free_rcu
free_htab_elem
pcpu_copy_value
fd_htab_map_needs_adjust
alloc_htab_elem
check_flags
htab_map_update_elem
htab_lru_map_update_elem
__htab_percpu_map_update_elem
__htab_lru_percpu_map_update_elem
htab_percpu_map_update_elem
htab_lru_percpu_map_update_elem
htab_map_delete_elem
htab_lru_map_delete_elem
delete_all_elements
htab_map_free
htab_map_seq_show_elem
htab_percpu_map_lookup_elem
htab_lru_percpu_map_lookup_elem
bpf_percpu_hash_copy
bpf_percpu_hash_update
htab_percpu_map_seq_show_elem
fd_htab_map_alloc_check
fd_htab_map_free
bpf_fd_htab_map_lookup_elem
bpf_fd_htab_map_update_elem
htab_of_map_alloc
htab_of_map_lookup_elem
htab_of_map_gen_lookup
htab_of_map_free
   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
   3  * Copyright (c) 2016 Facebook
   4  */
   5 #include <linux/bpf.h>
   6 #include <linux/btf.h>
   7 #include <linux/jhash.h>
   8 #include <linux/filter.h>
   9 #include <linux/rculist_nulls.h>
  10 #include <linux/random.h>
  11 #include <uapi/linux/btf.h>
  12 #include "percpu_freelist.h"
  13 #include "bpf_lru_list.h"
  14 #include "map_in_map.h"
  15 
  16 #define HTAB_CREATE_FLAG_MASK                                           \
  17         (BPF_F_NO_PREALLOC | BPF_F_NO_COMMON_LRU | BPF_F_NUMA_NODE |    \
  18          BPF_F_ACCESS_MASK | BPF_F_ZERO_SEED)
  19 
  20 struct bucket {
  21         struct hlist_nulls_head head;
  22         raw_spinlock_t lock;
  23 };
  24 
  25 struct bpf_htab {
  26         struct bpf_map map;
  27         struct bucket *buckets;
  28         void *elems;
  29         union {
  30                 struct pcpu_freelist freelist;
  31                 struct bpf_lru lru;
  32         };
  33         struct htab_elem *__percpu *extra_elems;
  34         atomic_t count; /* number of elements in this hashtable */
  35         u32 n_buckets;  /* number of hash buckets */
  36         u32 elem_size;  /* size of each element in bytes */
  37         u32 hashrnd;
  38 };
  39 
  40 /* each htab element is struct htab_elem + key + value */
  41 struct htab_elem {
  42         union {
  43                 struct hlist_nulls_node hash_node;
  44                 struct {
  45                         void *padding;
  46                         union {
  47                                 struct bpf_htab *htab;
  48                                 struct pcpu_freelist_node fnode;
  49                         };
  50                 };
  51         };
  52         union {
  53                 struct rcu_head rcu;
  54                 struct bpf_lru_node lru_node;
  55         };
  56         u32 hash;
  57         char key[0] __aligned(8);
  58 };
  59 
  60 static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node);
  61 
  62 static bool htab_is_lru(const struct bpf_htab *htab)
  63 {
  64         return htab->map.map_type == BPF_MAP_TYPE_LRU_HASH ||
  65                 htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;
  66 }
  67 
  68 static bool htab_is_percpu(const struct bpf_htab *htab)
  69 {
  70         return htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH ||
  71                 htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;
  72 }
  73 
  74 static bool htab_is_prealloc(const struct bpf_htab *htab)
  75 {
  76         return !(htab->map.map_flags & BPF_F_NO_PREALLOC);
  77 }
  78 
  79 static inline void htab_elem_set_ptr(struct htab_elem *l, u32 key_size,
  80                                      void __percpu *pptr)
  81 {
  82         *(void __percpu **)(l->key + key_size) = pptr;
  83 }
  84 
  85 static inline void __percpu *htab_elem_get_ptr(struct htab_elem *l, u32 key_size)
  86 {
  87         return *(void __percpu **)(l->key + key_size);
  88 }
  89 
  90 static void *fd_htab_map_get_ptr(const struct bpf_map *map, struct htab_elem *l)
  91 {
  92         return *(void **)(l->key + roundup(map->key_size, 8));
  93 }
  94 
  95 static struct htab_elem *get_htab_elem(struct bpf_htab *htab, int i)
  96 {
  97         return (struct htab_elem *) (htab->elems + i * htab->elem_size);
  98 }
  99 
 100 static void htab_free_elems(struct bpf_htab *htab)
 101 {
 102         int i;
 103 
 104         if (!htab_is_percpu(htab))
 105                 goto free_elems;
 106 
 107         for (i = 0; i < htab->map.max_entries; i++) {
 108                 void __percpu *pptr;
 109 
 110                 pptr = htab_elem_get_ptr(get_htab_elem(htab, i),
 111                                          htab->map.key_size);
 112                 free_percpu(pptr);
 113                 cond_resched();
 114         }
 115 free_elems:
 116         bpf_map_area_free(htab->elems);
 117 }
 118 
 119 static struct htab_elem *prealloc_lru_pop(struct bpf_htab *htab, void *key,
 120                                           u32 hash)
 121 {
 122         struct bpf_lru_node *node = bpf_lru_pop_free(&htab->lru, hash);
 123         struct htab_elem *l;
 124 
 125         if (node) {
 126                 l = container_of(node, struct htab_elem, lru_node);
 127                 memcpy(l->key, key, htab->map.key_size);
 128                 return l;
 129         }
 130 
 131         return NULL;
 132 }
 133 
 134 static int prealloc_init(struct bpf_htab *htab)
 135 {
 136         u32 num_entries = htab->map.max_entries;
 137         int err = -ENOMEM, i;
 138 
 139         if (!htab_is_percpu(htab) && !htab_is_lru(htab))
 140                 num_entries += num_possible_cpus();
 141 
 142         htab->elems = bpf_map_area_alloc(htab->elem_size * num_entries,
 143                                          htab->map.numa_node);
 144         if (!htab->elems)
 145                 return -ENOMEM;
 146 
 147         if (!htab_is_percpu(htab))
 148                 goto skip_percpu_elems;
 149 
 150         for (i = 0; i < num_entries; i++) {
 151                 u32 size = round_up(htab->map.value_size, 8);
 152                 void __percpu *pptr;
 153 
 154                 pptr = __alloc_percpu_gfp(size, 8, GFP_USER | __GFP_NOWARN);
 155                 if (!pptr)
 156                         goto free_elems;
 157                 htab_elem_set_ptr(get_htab_elem(htab, i), htab->map.key_size,
 158                                   pptr);
 159                 cond_resched();
 160         }
 161 
 162 skip_percpu_elems:
 163         if (htab_is_lru(htab))
 164                 err = bpf_lru_init(&htab->lru,
 165                                    htab->map.map_flags & BPF_F_NO_COMMON_LRU,
 166                                    offsetof(struct htab_elem, hash) -
 167                                    offsetof(struct htab_elem, lru_node),
 168                                    htab_lru_map_delete_node,
 169                                    htab);
 170         else
 171                 err = pcpu_freelist_init(&htab->freelist);
 172 
 173         if (err)
 174                 goto free_elems;
 175 
 176         if (htab_is_lru(htab))
 177                 bpf_lru_populate(&htab->lru, htab->elems,
 178                                  offsetof(struct htab_elem, lru_node),
 179                                  htab->elem_size, num_entries);
 180         else
 181                 pcpu_freelist_populate(&htab->freelist,
 182                                        htab->elems + offsetof(struct htab_elem, fnode),
 183                                        htab->elem_size, num_entries);
 184 
 185         return 0;
 186 
 187 free_elems:
 188         htab_free_elems(htab);
 189         return err;
 190 }
 191 
 192 static void prealloc_destroy(struct bpf_htab *htab)
 193 {
 194         htab_free_elems(htab);
 195 
 196         if (htab_is_lru(htab))
 197                 bpf_lru_destroy(&htab->lru);
 198         else
 199                 pcpu_freelist_destroy(&htab->freelist);
 200 }
 201 
 202 static int alloc_extra_elems(struct bpf_htab *htab)
 203 {
 204         struct htab_elem *__percpu *pptr, *l_new;
 205         struct pcpu_freelist_node *l;
 206         int cpu;
 207 
 208         pptr = __alloc_percpu_gfp(sizeof(struct htab_elem *), 8,
 209                                   GFP_USER | __GFP_NOWARN);
 210         if (!pptr)
 211                 return -ENOMEM;
 212 
 213         for_each_possible_cpu(cpu) {
 214                 l = pcpu_freelist_pop(&htab->freelist);
 215                 /* pop will succeed, since prealloc_init()
 216                  * preallocated extra num_possible_cpus elements
 217                  */
 218                 l_new = container_of(l, struct htab_elem, fnode);
 219                 *per_cpu_ptr(pptr, cpu) = l_new;
 220         }
 221         htab->extra_elems = pptr;
 222         return 0;
 223 }
 224 
 225 /* Called from syscall */
 226 static int htab_map_alloc_check(union bpf_attr *attr)
 227 {
 228         bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
 229                        attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
 230         bool lru = (attr->map_type == BPF_MAP_TYPE_LRU_HASH ||
 231                     attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
 232         /* percpu_lru means each cpu has its own LRU list.
 233          * it is different from BPF_MAP_TYPE_PERCPU_HASH where
 234          * the map's value itself is percpu.  percpu_lru has
 235          * nothing to do with the map's value.
 236          */
 237         bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU);
 238         bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC);
 239         bool zero_seed = (attr->map_flags & BPF_F_ZERO_SEED);
 240         int numa_node = bpf_map_attr_numa_node(attr);
 241 
 242         BUILD_BUG_ON(offsetof(struct htab_elem, htab) !=
 243                      offsetof(struct htab_elem, hash_node.pprev));
 244         BUILD_BUG_ON(offsetof(struct htab_elem, fnode.next) !=
 245                      offsetof(struct htab_elem, hash_node.pprev));
 246 
 247         if (lru && !capable(CAP_SYS_ADMIN))
 248                 /* LRU implementation is much complicated than other
 249                  * maps.  Hence, limit to CAP_SYS_ADMIN for now.
 250                  */
 251                 return -EPERM;
 252 
 253         if (zero_seed && !capable(CAP_SYS_ADMIN))
 254                 /* Guard against local DoS, and discourage production use. */
 255                 return -EPERM;
 256 
 257         if (attr->map_flags & ~HTAB_CREATE_FLAG_MASK ||
 258             !bpf_map_flags_access_ok(attr->map_flags))
 259                 return -EINVAL;
 260 
 261         if (!lru && percpu_lru)
 262                 return -EINVAL;
 263 
 264         if (lru && !prealloc)
 265                 return -ENOTSUPP;
 266 
 267         if (numa_node != NUMA_NO_NODE && (percpu || percpu_lru))
 268                 return -EINVAL;
 269 
 270         /* check sanity of attributes.
 271          * value_size == 0 may be allowed in the future to use map as a set
 272          */
 273         if (attr->max_entries == 0 || attr->key_size == 0 ||
 274             attr->value_size == 0)
 275                 return -EINVAL;
 276 
 277         if (attr->key_size > MAX_BPF_STACK)
 278                 /* eBPF programs initialize keys on stack, so they cannot be
 279                  * larger than max stack size
 280                  */
 281                 return -E2BIG;
 282 
 283         if (attr->value_size >= KMALLOC_MAX_SIZE -
 284             MAX_BPF_STACK - sizeof(struct htab_elem))
 285                 /* if value_size is bigger, the user space won't be able to
 286                  * access the elements via bpf syscall. This check also makes
 287                  * sure that the elem_size doesn't overflow and it's
 288                  * kmalloc-able later in htab_map_update_elem()
 289                  */
 290                 return -E2BIG;
 291 
 292         return 0;
 293 }
 294 
 295 static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
 296 {
 297         bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
 298                        attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
 299         bool lru = (attr->map_type == BPF_MAP_TYPE_LRU_HASH ||
 300                     attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
 301         /* percpu_lru means each cpu has its own LRU list.
 302          * it is different from BPF_MAP_TYPE_PERCPU_HASH where
 303          * the map's value itself is percpu.  percpu_lru has
 304          * nothing to do with the map's value.
 305          */
 306         bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU);
 307         bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC);
 308         struct bpf_htab *htab;
 309         int err, i;
 310         u64 cost;
 311 
 312         htab = kzalloc(sizeof(*htab), GFP_USER);
 313         if (!htab)
 314                 return ERR_PTR(-ENOMEM);
 315 
 316         bpf_map_init_from_attr(&htab->map, attr);
 317 
 318         if (percpu_lru) {
 319                 /* ensure each CPU's lru list has >=1 elements.
 320                  * since we are at it, make each lru list has the same
 321                  * number of elements.
 322                  */
 323                 htab->map.max_entries = roundup(attr->max_entries,
 324                                                 num_possible_cpus());
 325                 if (htab->map.max_entries < attr->max_entries)
 326                         htab->map.max_entries = rounddown(attr->max_entries,
 327                                                           num_possible_cpus());
 328         }
 329 
 330         /* hash table size must be power of 2 */
 331         htab->n_buckets = roundup_pow_of_two(htab->map.max_entries);
 332 
 333         htab->elem_size = sizeof(struct htab_elem) +
 334                           round_up(htab->map.key_size, 8);
 335         if (percpu)
 336                 htab->elem_size += sizeof(void *);
 337         else
 338                 htab->elem_size += round_up(htab->map.value_size, 8);
 339 
 340         err = -E2BIG;
 341         /* prevent zero size kmalloc and check for u32 overflow */
 342         if (htab->n_buckets == 0 ||
 343             htab->n_buckets > U32_MAX / sizeof(struct bucket))
 344                 goto free_htab;
 345 
 346         cost = (u64) htab->n_buckets * sizeof(struct bucket) +
 347                (u64) htab->elem_size * htab->map.max_entries;
 348 
 349         if (percpu)
 350                 cost += (u64) round_up(htab->map.value_size, 8) *
 351                         num_possible_cpus() * htab->map.max_entries;
 352         else
 353                cost += (u64) htab->elem_size * num_possible_cpus();
 354 
 355         /* if map size is larger than memlock limit, reject it */
 356         err = bpf_map_charge_init(&htab->map.memory, cost);
 357         if (err)
 358                 goto free_htab;
 359 
 360         err = -ENOMEM;
 361         htab->buckets = bpf_map_area_alloc(htab->n_buckets *
 362                                            sizeof(struct bucket),
 363                                            htab->map.numa_node);
 364         if (!htab->buckets)
 365                 goto free_charge;
 366 
 367         if (htab->map.map_flags & BPF_F_ZERO_SEED)
 368                 htab->hashrnd = 0;
 369         else
 370                 htab->hashrnd = get_random_int();
 371 
 372         for (i = 0; i < htab->n_buckets; i++) {
 373                 INIT_HLIST_NULLS_HEAD(&htab->buckets[i].head, i);
 374                 raw_spin_lock_init(&htab->buckets[i].lock);
 375         }
 376 
 377         if (prealloc) {
 378                 err = prealloc_init(htab);
 379                 if (err)
 380                         goto free_buckets;
 381 
 382                 if (!percpu && !lru) {
 383                         /* lru itself can remove the least used element, so
 384                          * there is no need for an extra elem during map_update.
 385                          */
 386                         err = alloc_extra_elems(htab);
 387                         if (err)
 388                                 goto free_prealloc;
 389                 }
 390         }
 391 
 392         return &htab->map;
 393 
 394 free_prealloc:
 395         prealloc_destroy(htab);
 396 free_buckets:
 397         bpf_map_area_free(htab->buckets);
 398 free_charge:
 399         bpf_map_charge_finish(&htab->map.memory);
 400 free_htab:
 401         kfree(htab);
 402         return ERR_PTR(err);
 403 }
 404 
 405 static inline u32 htab_map_hash(const void *key, u32 key_len, u32 hashrnd)
 406 {
 407         return jhash(key, key_len, hashrnd);
 408 }
 409 
 410 static inline struct bucket *__select_bucket(struct bpf_htab *htab, u32 hash)
 411 {
 412         return &htab->buckets[hash & (htab->n_buckets - 1)];
 413 }
 414 
 415 static inline struct hlist_nulls_head *select_bucket(struct bpf_htab *htab, u32 hash)
 416 {
 417         return &__select_bucket(htab, hash)->head;
 418 }
 419 
 420 /* this lookup function can only be called with bucket lock taken */
 421 static struct htab_elem *lookup_elem_raw(struct hlist_nulls_head *head, u32 hash,
 422                                          void *key, u32 key_size)
 423 {
 424         struct hlist_nulls_node *n;
 425         struct htab_elem *l;
 426 
 427         hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
 428                 if (l->hash == hash && !memcmp(&l->key, key, key_size))
 429                         return l;
 430 
 431         return NULL;
 432 }
 433 
 434 /* can be called without bucket lock. it will repeat the loop in
 435  * the unlikely event when elements moved from one bucket into another
 436  * while link list is being walked
 437  */
 438 static struct htab_elem *lookup_nulls_elem_raw(struct hlist_nulls_head *head,
 439                                                u32 hash, void *key,
 440                                                u32 key_size, u32 n_buckets)
 441 {
 442         struct hlist_nulls_node *n;
 443         struct htab_elem *l;
 444 
 445 again:
 446         hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
 447                 if (l->hash == hash && !memcmp(&l->key, key, key_size))
 448                         return l;
 449 
 450         if (unlikely(get_nulls_value(n) != (hash & (n_buckets - 1))))
 451                 goto again;
 452 
 453         return NULL;
 454 }
 455 
 456 /* Called from syscall or from eBPF program directly, so
 457  * arguments have to match bpf_map_lookup_elem() exactly.
 458  * The return value is adjusted by BPF instructions
 459  * in htab_map_gen_lookup().
 460  */
 461 static void *__htab_map_lookup_elem(struct bpf_map *map, void *key)
 462 {
 463         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
 464         struct hlist_nulls_head *head;
 465         struct htab_elem *l;
 466         u32 hash, key_size;
 467 
 468         /* Must be called with rcu_read_lock. */
 469         WARN_ON_ONCE(!rcu_read_lock_held());
 470 
 471         key_size = map->key_size;
 472 
 473         hash = htab_map_hash(key, key_size, htab->hashrnd);
 474 
 475         head = select_bucket(htab, hash);
 476 
 477         l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);
 478 
 479         return l;
 480 }
 481 
 482 static void *htab_map_lookup_elem(struct bpf_map *map, void *key)
 483 {
 484         struct htab_elem *l = __htab_map_lookup_elem(map, key);
 485 
 486         if (l)
 487                 return l->key + round_up(map->key_size, 8);
 488 
 489         return NULL;
 490 }
 491 
 492 /* inline bpf_map_lookup_elem() call.
 493  * Instead of:
 494  * bpf_prog
 495  *   bpf_map_lookup_elem
 496  *     map->ops->map_lookup_elem
 497  *       htab_map_lookup_elem
 498  *         __htab_map_lookup_elem
 499  * do:
 500  * bpf_prog
 501  *   __htab_map_lookup_elem
 502  */
 503 static u32 htab_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
 504 {
 505         struct bpf_insn *insn = insn_buf;
 506         const int ret = BPF_REG_0;
 507 
 508         BUILD_BUG_ON(!__same_type(&__htab_map_lookup_elem,
 509                      (void *(*)(struct bpf_map *map, void *key))NULL));
 510         *insn++ = BPF_EMIT_CALL(BPF_CAST_CALL(__htab_map_lookup_elem));
 511         *insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 1);
 512         *insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
 513                                 offsetof(struct htab_elem, key) +
 514                                 round_up(map->key_size, 8));
 515         return insn - insn_buf;
 516 }
 517 
 518 static __always_inline void *__htab_lru_map_lookup_elem(struct bpf_map *map,
 519                                                         void *key, const bool mark)
 520 {
 521         struct htab_elem *l = __htab_map_lookup_elem(map, key);
 522 
 523         if (l) {
 524                 if (mark)
 525                         bpf_lru_node_set_ref(&l->lru_node);
 526                 return l->key + round_up(map->key_size, 8);
 527         }
 528 
 529         return NULL;
 530 }
 531 
 532 static void *htab_lru_map_lookup_elem(struct bpf_map *map, void *key)
 533 {
 534         return __htab_lru_map_lookup_elem(map, key, true);
 535 }
 536 
 537 static void *htab_lru_map_lookup_elem_sys(struct bpf_map *map, void *key)
 538 {
 539         return __htab_lru_map_lookup_elem(map, key, false);
 540 }
 541 
 542 static u32 htab_lru_map_gen_lookup(struct bpf_map *map,
 543                                    struct bpf_insn *insn_buf)
 544 {
 545         struct bpf_insn *insn = insn_buf;
 546         const int ret = BPF_REG_0;
 547         const int ref_reg = BPF_REG_1;
 548 
 549         BUILD_BUG_ON(!__same_type(&__htab_map_lookup_elem,
 550                      (void *(*)(struct bpf_map *map, void *key))NULL));
 551         *insn++ = BPF_EMIT_CALL(BPF_CAST_CALL(__htab_map_lookup_elem));
 552         *insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 4);
 553         *insn++ = BPF_LDX_MEM(BPF_B, ref_reg, ret,
 554                               offsetof(struct htab_elem, lru_node) +
 555                               offsetof(struct bpf_lru_node, ref));
 556         *insn++ = BPF_JMP_IMM(BPF_JNE, ref_reg, 0, 1);
 557         *insn++ = BPF_ST_MEM(BPF_B, ret,
 558                              offsetof(struct htab_elem, lru_node) +
 559                              offsetof(struct bpf_lru_node, ref),
 560                              1);
 561         *insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
 562                                 offsetof(struct htab_elem, key) +
 563                                 round_up(map->key_size, 8));
 564         return insn - insn_buf;
 565 }
 566 
 567 /* It is called from the bpf_lru_list when the LRU needs to delete
 568  * older elements from the htab.
 569  */
 570 static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node)
 571 {
 572         struct bpf_htab *htab = (struct bpf_htab *)arg;
 573         struct htab_elem *l = NULL, *tgt_l;
 574         struct hlist_nulls_head *head;
 575         struct hlist_nulls_node *n;
 576         unsigned long flags;
 577         struct bucket *b;
 578 
 579         tgt_l = container_of(node, struct htab_elem, lru_node);
 580         b = __select_bucket(htab, tgt_l->hash);
 581         head = &b->head;
 582 
 583         raw_spin_lock_irqsave(&b->lock, flags);
 584 
 585         hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
 586                 if (l == tgt_l) {
 587                         hlist_nulls_del_rcu(&l->hash_node);
 588                         break;
 589                 }
 590 
 591         raw_spin_unlock_irqrestore(&b->lock, flags);
 592 
 593         return l == tgt_l;
 594 }
 595 
 596 /* Called from syscall */
 597 static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
 598 {
 599         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
 600         struct hlist_nulls_head *head;
 601         struct htab_elem *l, *next_l;
 602         u32 hash, key_size;
 603         int i = 0;
 604 
 605         WARN_ON_ONCE(!rcu_read_lock_held());
 606 
 607         key_size = map->key_size;
 608 
 609         if (!key)
 610                 goto find_first_elem;
 611 
 612         hash = htab_map_hash(key, key_size, htab->hashrnd);
 613 
 614         head = select_bucket(htab, hash);
 615 
 616         /* lookup the key */
 617         l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);
 618 
 619         if (!l)
 620                 goto find_first_elem;
 621 
 622         /* key was found, get next key in the same bucket */
 623         next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_next_rcu(&l->hash_node)),
 624                                   struct htab_elem, hash_node);
 625 
 626         if (next_l) {
 627                 /* if next elem in this hash list is non-zero, just return it */
 628                 memcpy(next_key, next_l->key, key_size);
 629                 return 0;
 630         }
 631 
 632         /* no more elements in this hash list, go to the next bucket */
 633         i = hash & (htab->n_buckets - 1);
 634         i++;
 635 
 636 find_first_elem:
 637         /* iterate over buckets */
 638         for (; i < htab->n_buckets; i++) {
 639                 head = select_bucket(htab, i);
 640 
 641                 /* pick first element in the bucket */
 642                 next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_first_rcu(head)),
 643                                           struct htab_elem, hash_node);
 644                 if (next_l) {
 645                         /* if it's not empty, just return it */
 646                         memcpy(next_key, next_l->key, key_size);
 647                         return 0;
 648                 }
 649         }
 650 
 651         /* iterated over all buckets and all elements */
 652         return -ENOENT;
 653 }
 654 
 655 static void htab_elem_free(struct bpf_htab *htab, struct htab_elem *l)
 656 {
 657         if (htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH)
 658                 free_percpu(htab_elem_get_ptr(l, htab->map.key_size));
 659         kfree(l);
 660 }
 661 
 662 static void htab_elem_free_rcu(struct rcu_head *head)
 663 {
 664         struct htab_elem *l = container_of(head, struct htab_elem, rcu);
 665         struct bpf_htab *htab = l->htab;
 666 
 667         /* must increment bpf_prog_active to avoid kprobe+bpf triggering while
 668          * we're calling kfree, otherwise deadlock is possible if kprobes
 669          * are placed somewhere inside of slub
 670          */
 671         preempt_disable();
 672         __this_cpu_inc(bpf_prog_active);
 673         htab_elem_free(htab, l);
 674         __this_cpu_dec(bpf_prog_active);
 675         preempt_enable();
 676 }
 677 
 678 static void free_htab_elem(struct bpf_htab *htab, struct htab_elem *l)
 679 {
 680         struct bpf_map *map = &htab->map;
 681 
 682         if (map->ops->map_fd_put_ptr) {
 683                 void *ptr = fd_htab_map_get_ptr(map, l);
 684 
 685                 map->ops->map_fd_put_ptr(ptr);
 686         }
 687 
 688         if (htab_is_prealloc(htab)) {
 689                 __pcpu_freelist_push(&htab->freelist, &l->fnode);
 690         } else {
 691                 atomic_dec(&htab->count);
 692                 l->htab = htab;
 693                 call_rcu(&l->rcu, htab_elem_free_rcu);
 694         }
 695 }
 696 
 697 static void pcpu_copy_value(struct bpf_htab *htab, void __percpu *pptr,
 698                             void *value, bool onallcpus)
 699 {
 700         if (!onallcpus) {
 701                 /* copy true value_size bytes */
 702                 memcpy(this_cpu_ptr(pptr), value, htab->map.value_size);
 703         } else {
 704                 u32 size = round_up(htab->map.value_size, 8);
 705                 int off = 0, cpu;
 706 
 707                 for_each_possible_cpu(cpu) {
 708                         bpf_long_memcpy(per_cpu_ptr(pptr, cpu),
 709                                         value + off, size);
 710                         off += size;
 711                 }
 712         }
 713 }
 714 
 715 static bool fd_htab_map_needs_adjust(const struct bpf_htab *htab)
 716 {
 717         return htab->map.map_type == BPF_MAP_TYPE_HASH_OF_MAPS &&
 718                BITS_PER_LONG == 64;
 719 }
 720 
 721 static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
 722                                          void *value, u32 key_size, u32 hash,
 723                                          bool percpu, bool onallcpus,
 724                                          struct htab_elem *old_elem)
 725 {
 726         u32 size = htab->map.value_size;
 727         bool prealloc = htab_is_prealloc(htab);
 728         struct htab_elem *l_new, **pl_new;
 729         void __percpu *pptr;
 730 
 731         if (prealloc) {
 732                 if (old_elem) {
 733                         /* if we're updating the existing element,
 734                          * use per-cpu extra elems to avoid freelist_pop/push
 735                          */
 736                         pl_new = this_cpu_ptr(htab->extra_elems);
 737                         l_new = *pl_new;
 738                         *pl_new = old_elem;
 739                 } else {
 740                         struct pcpu_freelist_node *l;
 741 
 742                         l = __pcpu_freelist_pop(&htab->freelist);
 743                         if (!l)
 744                                 return ERR_PTR(-E2BIG);
 745                         l_new = container_of(l, struct htab_elem, fnode);
 746                 }
 747         } else {
 748                 if (atomic_inc_return(&htab->count) > htab->map.max_entries)
 749                         if (!old_elem) {
 750                                 /* when map is full and update() is replacing
 751                                  * old element, it's ok to allocate, since
 752                                  * old element will be freed immediately.
 753                                  * Otherwise return an error
 754                                  */
 755                                 l_new = ERR_PTR(-E2BIG);
 756                                 goto dec_count;
 757                         }
 758                 l_new = kmalloc_node(htab->elem_size, GFP_ATOMIC | __GFP_NOWARN,
 759                                      htab->map.numa_node);
 760                 if (!l_new) {
 761                         l_new = ERR_PTR(-ENOMEM);
 762                         goto dec_count;
 763                 }
 764                 check_and_init_map_lock(&htab->map,
 765                                         l_new->key + round_up(key_size, 8));
 766         }
 767 
 768         memcpy(l_new->key, key, key_size);
 769         if (percpu) {
 770                 size = round_up(size, 8);
 771                 if (prealloc) {
 772                         pptr = htab_elem_get_ptr(l_new, key_size);
 773                 } else {
 774                         /* alloc_percpu zero-fills */
 775                         pptr = __alloc_percpu_gfp(size, 8,
 776                                                   GFP_ATOMIC | __GFP_NOWARN);
 777                         if (!pptr) {
 778                                 kfree(l_new);
 779                                 l_new = ERR_PTR(-ENOMEM);
 780                                 goto dec_count;
 781                         }
 782                 }
 783 
 784                 pcpu_copy_value(htab, pptr, value, onallcpus);
 785 
 786                 if (!prealloc)
 787                         htab_elem_set_ptr(l_new, key_size, pptr);
 788         } else if (fd_htab_map_needs_adjust(htab)) {
 789                 size = round_up(size, 8);
 790                 memcpy(l_new->key + round_up(key_size, 8), value, size);
 791         } else {
 792                 copy_map_value(&htab->map,
 793                                l_new->key + round_up(key_size, 8),
 794                                value);
 795         }
 796 
 797         l_new->hash = hash;
 798         return l_new;
 799 dec_count:
 800         atomic_dec(&htab->count);
 801         return l_new;
 802 }
 803 
 804 static int check_flags(struct bpf_htab *htab, struct htab_elem *l_old,
 805                        u64 map_flags)
 806 {
 807         if (l_old && (map_flags & ~BPF_F_LOCK) == BPF_NOEXIST)
 808                 /* elem already exists */
 809                 return -EEXIST;
 810 
 811         if (!l_old && (map_flags & ~BPF_F_LOCK) == BPF_EXIST)
 812                 /* elem doesn't exist, cannot update it */
 813                 return -ENOENT;
 814 
 815         return 0;
 816 }
 817 
 818 /* Called from syscall or from eBPF program */
 819 static int htab_map_update_elem(struct bpf_map *map, void *key, void *value,
 820                                 u64 map_flags)
 821 {
 822         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
 823         struct htab_elem *l_new = NULL, *l_old;
 824         struct hlist_nulls_head *head;
 825         unsigned long flags;
 826         struct bucket *b;
 827         u32 key_size, hash;
 828         int ret;
 829 
 830         if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST))
 831                 /* unknown flags */
 832                 return -EINVAL;
 833 
 834         WARN_ON_ONCE(!rcu_read_lock_held());
 835 
 836         key_size = map->key_size;
 837 
 838         hash = htab_map_hash(key, key_size, htab->hashrnd);
 839 
 840         b = __select_bucket(htab, hash);
 841         head = &b->head;
 842 
 843         if (unlikely(map_flags & BPF_F_LOCK)) {
 844                 if (unlikely(!map_value_has_spin_lock(map)))
 845                         return -EINVAL;
 846                 /* find an element without taking the bucket lock */
 847                 l_old = lookup_nulls_elem_raw(head, hash, key, key_size,
 848                                               htab->n_buckets);
 849                 ret = check_flags(htab, l_old, map_flags);
 850                 if (ret)
 851                         return ret;
 852                 if (l_old) {
 853                         /* grab the element lock and update value in place */
 854                         copy_map_value_locked(map,
 855                                               l_old->key + round_up(key_size, 8),
 856                                               value, false);
 857                         return 0;
 858                 }
 859                 /* fall through, grab the bucket lock and lookup again.
 860                  * 99.9% chance that the element won't be found,
 861                  * but second lookup under lock has to be done.
 862                  */
 863         }
 864 
 865         /* bpf_map_update_elem() can be called in_irq() */
 866         raw_spin_lock_irqsave(&b->lock, flags);
 867 
 868         l_old = lookup_elem_raw(head, hash, key, key_size);
 869 
 870         ret = check_flags(htab, l_old, map_flags);
 871         if (ret)
 872                 goto err;
 873 
 874         if (unlikely(l_old && (map_flags & BPF_F_LOCK))) {
 875                 /* first lookup without the bucket lock didn't find the element,
 876                  * but second lookup with the bucket lock found it.
 877                  * This case is highly unlikely, but has to be dealt with:
 878                  * grab the element lock in addition to the bucket lock
 879                  * and update element in place
 880                  */
 881                 copy_map_value_locked(map,
 882                                       l_old->key + round_up(key_size, 8),
 883                                       value, false);
 884                 ret = 0;
 885                 goto err;
 886         }
 887 
 888         l_new = alloc_htab_elem(htab, key, value, key_size, hash, false, false,
 889                                 l_old);
 890         if (IS_ERR(l_new)) {
 891                 /* all pre-allocated elements are in use or memory exhausted */
 892                 ret = PTR_ERR(l_new);
 893                 goto err;
 894         }
 895 
 896         /* add new element to the head of the list, so that
 897          * concurrent search will find it before old elem
 898          */
 899         hlist_nulls_add_head_rcu(&l_new->hash_node, head);
 900         if (l_old) {
 901                 hlist_nulls_del_rcu(&l_old->hash_node);
 902                 if (!htab_is_prealloc(htab))
 903                         free_htab_elem(htab, l_old);
 904         }
 905         ret = 0;
 906 err:
 907         raw_spin_unlock_irqrestore(&b->lock, flags);
 908         return ret;
 909 }
 910 
 911 static int htab_lru_map_update_elem(struct bpf_map *map, void *key, void *value,
 912                                     u64 map_flags)
 913 {
 914         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
 915         struct htab_elem *l_new, *l_old = NULL;
 916         struct hlist_nulls_head *head;
 917         unsigned long flags;
 918         struct bucket *b;
 919         u32 key_size, hash;
 920         int ret;
 921 
 922         if (unlikely(map_flags > BPF_EXIST))
 923                 /* unknown flags */
 924                 return -EINVAL;
 925 
 926         WARN_ON_ONCE(!rcu_read_lock_held());
 927 
 928         key_size = map->key_size;
 929 
 930         hash = htab_map_hash(key, key_size, htab->hashrnd);
 931 
 932         b = __select_bucket(htab, hash);
 933         head = &b->head;
 934 
 935         /* For LRU, we need to alloc before taking bucket's
 936          * spinlock because getting free nodes from LRU may need
 937          * to remove older elements from htab and this removal
 938          * operation will need a bucket lock.
 939          */
 940         l_new = prealloc_lru_pop(htab, key, hash);
 941         if (!l_new)
 942                 return -ENOMEM;
 943         memcpy(l_new->key + round_up(map->key_size, 8), value, map->value_size);
 944 
 945         /* bpf_map_update_elem() can be called in_irq() */
 946         raw_spin_lock_irqsave(&b->lock, flags);
 947 
 948         l_old = lookup_elem_raw(head, hash, key, key_size);
 949 
 950         ret = check_flags(htab, l_old, map_flags);
 951         if (ret)
 952                 goto err;
 953 
 954         /* add new element to the head of the list, so that
 955          * concurrent search will find it before old elem
 956          */
 957         hlist_nulls_add_head_rcu(&l_new->hash_node, head);
 958         if (l_old) {
 959                 bpf_lru_node_set_ref(&l_new->lru_node);
 960                 hlist_nulls_del_rcu(&l_old->hash_node);
 961         }
 962         ret = 0;
 963 
 964 err:
 965         raw_spin_unlock_irqrestore(&b->lock, flags);
 966 
 967         if (ret)
 968                 bpf_lru_push_free(&htab->lru, &l_new->lru_node);
 969         else if (l_old)
 970                 bpf_lru_push_free(&htab->lru, &l_old->lru_node);
 971 
 972         return ret;
 973 }
 974 
 975 static int __htab_percpu_map_update_elem(struct bpf_map *map, void *key,
 976                                          void *value, u64 map_flags,
 977                                          bool onallcpus)
 978 {
 979         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
 980         struct htab_elem *l_new = NULL, *l_old;
 981         struct hlist_nulls_head *head;
 982         unsigned long flags;
 983         struct bucket *b;
 984         u32 key_size, hash;
 985         int ret;
 986 
 987         if (unlikely(map_flags > BPF_EXIST))
 988                 /* unknown flags */
 989                 return -EINVAL;
 990 
 991         WARN_ON_ONCE(!rcu_read_lock_held());
 992 
 993         key_size = map->key_size;
 994 
 995         hash = htab_map_hash(key, key_size, htab->hashrnd);
 996 
 997         b = __select_bucket(htab, hash);
 998         head = &b->head;
 999 
1000         /* bpf_map_update_elem() can be called in_irq() */
1001         raw_spin_lock_irqsave(&b->lock, flags);
1002 
1003         l_old = lookup_elem_raw(head, hash, key, key_size);
1004 
1005         ret = check_flags(htab, l_old, map_flags);
1006         if (ret)
1007                 goto err;
1008 
1009         if (l_old) {
1010                 /* per-cpu hash map can update value in-place */
1011                 pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),
1012                                 value, onallcpus);
1013         } else {
1014                 l_new = alloc_htab_elem(htab, key, value, key_size,
1015                                         hash, true, onallcpus, NULL);
1016                 if (IS_ERR(l_new)) {
1017                         ret = PTR_ERR(l_new);
1018                         goto err;
1019                 }
1020                 hlist_nulls_add_head_rcu(&l_new->hash_node, head);
1021         }
1022         ret = 0;
1023 err:
1024         raw_spin_unlock_irqrestore(&b->lock, flags);
1025         return ret;
1026 }
1027 
1028 static int __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
1029                                              void *value, u64 map_flags,
1030                                              bool onallcpus)
1031 {
1032         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1033         struct htab_elem *l_new = NULL, *l_old;
1034         struct hlist_nulls_head *head;
1035         unsigned long flags;
1036         struct bucket *b;
1037         u32 key_size, hash;
1038         int ret;
1039 
1040         if (unlikely(map_flags > BPF_EXIST))
1041                 /* unknown flags */
1042                 return -EINVAL;
1043 
1044         WARN_ON_ONCE(!rcu_read_lock_held());
1045 
1046         key_size = map->key_size;
1047 
1048         hash = htab_map_hash(key, key_size, htab->hashrnd);
1049 
1050         b = __select_bucket(htab, hash);
1051         head = &b->head;
1052 
1053         /* For LRU, we need to alloc before taking bucket's
1054          * spinlock because LRU's elem alloc may need
1055          * to remove older elem from htab and this removal
1056          * operation will need a bucket lock.
1057          */
1058         if (map_flags != BPF_EXIST) {
1059                 l_new = prealloc_lru_pop(htab, key, hash);
1060                 if (!l_new)
1061                         return -ENOMEM;
1062         }
1063 
1064         /* bpf_map_update_elem() can be called in_irq() */
1065         raw_spin_lock_irqsave(&b->lock, flags);
1066 
1067         l_old = lookup_elem_raw(head, hash, key, key_size);
1068 
1069         ret = check_flags(htab, l_old, map_flags);
1070         if (ret)
1071                 goto err;
1072 
1073         if (l_old) {
1074                 bpf_lru_node_set_ref(&l_old->lru_node);
1075 
1076                 /* per-cpu hash map can update value in-place */
1077                 pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),
1078                                 value, onallcpus);
1079         } else {
1080                 pcpu_copy_value(htab, htab_elem_get_ptr(l_new, key_size),
1081                                 value, onallcpus);
1082                 hlist_nulls_add_head_rcu(&l_new->hash_node, head);
1083                 l_new = NULL;
1084         }
1085         ret = 0;
1086 err:
1087         raw_spin_unlock_irqrestore(&b->lock, flags);
1088         if (l_new)
1089                 bpf_lru_push_free(&htab->lru, &l_new->lru_node);
1090         return ret;
1091 }
1092 
1093 static int htab_percpu_map_update_elem(struct bpf_map *map, void *key,
1094                                        void *value, u64 map_flags)
1095 {
1096         return __htab_percpu_map_update_elem(map, key, value, map_flags, false);
1097 }
1098 
1099 static int htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
1100                                            void *value, u64 map_flags)
1101 {
1102         return __htab_lru_percpu_map_update_elem(map, key, value, map_flags,
1103                                                  false);
1104 }
1105 
1106 /* Called from syscall or from eBPF program */
1107 static int htab_map_delete_elem(struct bpf_map *map, void *key)
1108 {
1109         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1110         struct hlist_nulls_head *head;
1111         struct bucket *b;
1112         struct htab_elem *l;
1113         unsigned long flags;
1114         u32 hash, key_size;
1115         int ret = -ENOENT;
1116 
1117         WARN_ON_ONCE(!rcu_read_lock_held());
1118 
1119         key_size = map->key_size;
1120 
1121         hash = htab_map_hash(key, key_size, htab->hashrnd);
1122         b = __select_bucket(htab, hash);
1123         head = &b->head;
1124 
1125         raw_spin_lock_irqsave(&b->lock, flags);
1126 
1127         l = lookup_elem_raw(head, hash, key, key_size);
1128 
1129         if (l) {
1130                 hlist_nulls_del_rcu(&l->hash_node);
1131                 free_htab_elem(htab, l);
1132                 ret = 0;
1133         }
1134 
1135         raw_spin_unlock_irqrestore(&b->lock, flags);
1136         return ret;
1137 }
1138 
1139 static int htab_lru_map_delete_elem(struct bpf_map *map, void *key)
1140 {
1141         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1142         struct hlist_nulls_head *head;
1143         struct bucket *b;
1144         struct htab_elem *l;
1145         unsigned long flags;
1146         u32 hash, key_size;
1147         int ret = -ENOENT;
1148 
1149         WARN_ON_ONCE(!rcu_read_lock_held());
1150 
1151         key_size = map->key_size;
1152 
1153         hash = htab_map_hash(key, key_size, htab->hashrnd);
1154         b = __select_bucket(htab, hash);
1155         head = &b->head;
1156 
1157         raw_spin_lock_irqsave(&b->lock, flags);
1158 
1159         l = lookup_elem_raw(head, hash, key, key_size);
1160 
1161         if (l) {
1162                 hlist_nulls_del_rcu(&l->hash_node);
1163                 ret = 0;
1164         }
1165 
1166         raw_spin_unlock_irqrestore(&b->lock, flags);
1167         if (l)
1168                 bpf_lru_push_free(&htab->lru, &l->lru_node);
1169         return ret;
1170 }
1171 
1172 static void delete_all_elements(struct bpf_htab *htab)
1173 {
1174         int i;
1175 
1176         for (i = 0; i < htab->n_buckets; i++) {
1177                 struct hlist_nulls_head *head = select_bucket(htab, i);
1178                 struct hlist_nulls_node *n;
1179                 struct htab_elem *l;
1180 
1181                 hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
1182                         hlist_nulls_del_rcu(&l->hash_node);
1183                         htab_elem_free(htab, l);
1184                 }
1185         }
1186 }
1187 
1188 /* Called when map->refcnt goes to zero, either from workqueue or from syscall */
1189 static void htab_map_free(struct bpf_map *map)
1190 {
1191         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1192 
1193         /* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
1194          * so the programs (can be more than one that used this map) were
1195          * disconnected from events. Wait for outstanding critical sections in
1196          * these programs to complete
1197          */
1198         synchronize_rcu();
1199 
1200         /* some of free_htab_elem() callbacks for elements of this map may
1201          * not have executed. Wait for them.
1202          */
1203         rcu_barrier();
1204         if (!htab_is_prealloc(htab))
1205                 delete_all_elements(htab);
1206         else
1207                 prealloc_destroy(htab);
1208 
1209         free_percpu(htab->extra_elems);
1210         bpf_map_area_free(htab->buckets);
1211         kfree(htab);
1212 }
1213 
1214 static void htab_map_seq_show_elem(struct bpf_map *map, void *key,
1215                                    struct seq_file *m)
1216 {
1217         void *value;
1218 
1219         rcu_read_lock();
1220 
1221         value = htab_map_lookup_elem(map, key);
1222         if (!value) {
1223                 rcu_read_unlock();
1224                 return;
1225         }
1226 
1227         btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
1228         seq_puts(m, ": ");
1229         btf_type_seq_show(map->btf, map->btf_value_type_id, value, m);
1230         seq_puts(m, "\n");
1231 
1232         rcu_read_unlock();
1233 }
1234 
1235 const struct bpf_map_ops htab_map_ops = {
1236         .map_alloc_check = htab_map_alloc_check,
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_map_lookup_elem,
1241         .map_update_elem = htab_map_update_elem,
1242         .map_delete_elem = htab_map_delete_elem,
1243         .map_gen_lookup = htab_map_gen_lookup,
1244         .map_seq_show_elem = htab_map_seq_show_elem,
1245 };
1246 
1247 const struct bpf_map_ops htab_lru_map_ops = {
1248         .map_alloc_check = htab_map_alloc_check,
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_map_lookup_elem,
1253         .map_lookup_elem_sys_only = htab_lru_map_lookup_elem_sys,
1254         .map_update_elem = htab_lru_map_update_elem,
1255         .map_delete_elem = htab_lru_map_delete_elem,
1256         .map_gen_lookup = htab_lru_map_gen_lookup,
1257         .map_seq_show_elem = htab_map_seq_show_elem,
1258 };
1259 
1260 /* Called from eBPF program */
1261 static void *htab_percpu_map_lookup_elem(struct bpf_map *map, void *key)
1262 {
1263         struct htab_elem *l = __htab_map_lookup_elem(map, key);
1264 
1265         if (l)
1266                 return this_cpu_ptr(htab_elem_get_ptr(l, map->key_size));
1267         else
1268                 return NULL;
1269 }
1270 
1271 static void *htab_lru_percpu_map_lookup_elem(struct bpf_map *map, void *key)
1272 {
1273         struct htab_elem *l = __htab_map_lookup_elem(map, key);
1274 
1275         if (l) {
1276                 bpf_lru_node_set_ref(&l->lru_node);
1277                 return this_cpu_ptr(htab_elem_get_ptr(l, map->key_size));
1278         }
1279 
1280         return NULL;
1281 }
1282 
1283 int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value)
1284 {
1285         struct htab_elem *l;
1286         void __percpu *pptr;
1287         int ret = -ENOENT;
1288         int cpu, off = 0;
1289         u32 size;
1290 
1291         /* per_cpu areas are zero-filled and bpf programs can only
1292          * access 'value_size' of them, so copying rounded areas
1293          * will not leak any kernel data
1294          */
1295         size = round_up(map->value_size, 8);
1296         rcu_read_lock();
1297         l = __htab_map_lookup_elem(map, key);
1298         if (!l)
1299                 goto out;
1300         /* We do not mark LRU map element here in order to not mess up
1301          * eviction heuristics when user space does a map walk.
1302          */
1303         pptr = htab_elem_get_ptr(l, map->key_size);
1304         for_each_possible_cpu(cpu) {
1305                 bpf_long_memcpy(value + off,
1306                                 per_cpu_ptr(pptr, cpu), size);
1307                 off += size;
1308         }
1309         ret = 0;
1310 out:
1311         rcu_read_unlock();
1312         return ret;
1313 }
1314 
1315 int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value,
1316                            u64 map_flags)
1317 {
1318         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1319         int ret;
1320 
1321         rcu_read_lock();
1322         if (htab_is_lru(htab))
1323                 ret = __htab_lru_percpu_map_update_elem(map, key, value,
1324                                                         map_flags, true);
1325         else
1326                 ret = __htab_percpu_map_update_elem(map, key, value, map_flags,
1327                                                     true);
1328         rcu_read_unlock();
1329 
1330         return ret;
1331 }
1332 
1333 static void htab_percpu_map_seq_show_elem(struct bpf_map *map, void *key,
1334                                           struct seq_file *m)
1335 {
1336         struct htab_elem *l;
1337         void __percpu *pptr;
1338         int cpu;
1339 
1340         rcu_read_lock();
1341 
1342         l = __htab_map_lookup_elem(map, key);
1343         if (!l) {
1344                 rcu_read_unlock();
1345                 return;
1346         }
1347 
1348         btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
1349         seq_puts(m, ": {\n");
1350         pptr = htab_elem_get_ptr(l, map->key_size);
1351         for_each_possible_cpu(cpu) {
1352                 seq_printf(m, "\tcpu%d: ", cpu);
1353                 btf_type_seq_show(map->btf, map->btf_value_type_id,
1354                                   per_cpu_ptr(pptr, cpu), m);
1355                 seq_puts(m, "\n");
1356         }
1357         seq_puts(m, "}\n");
1358 
1359         rcu_read_unlock();
1360 }
1361 
1362 const struct bpf_map_ops htab_percpu_map_ops = {
1363         .map_alloc_check = htab_map_alloc_check,
1364         .map_alloc = htab_map_alloc,
1365         .map_free = htab_map_free,
1366         .map_get_next_key = htab_map_get_next_key,
1367         .map_lookup_elem = htab_percpu_map_lookup_elem,
1368         .map_update_elem = htab_percpu_map_update_elem,
1369         .map_delete_elem = htab_map_delete_elem,
1370         .map_seq_show_elem = htab_percpu_map_seq_show_elem,
1371 };
1372 
1373 const struct bpf_map_ops htab_lru_percpu_map_ops = {
1374         .map_alloc_check = htab_map_alloc_check,
1375         .map_alloc = htab_map_alloc,
1376         .map_free = htab_map_free,
1377         .map_get_next_key = htab_map_get_next_key,
1378         .map_lookup_elem = htab_lru_percpu_map_lookup_elem,
1379         .map_update_elem = htab_lru_percpu_map_update_elem,
1380         .map_delete_elem = htab_lru_map_delete_elem,
1381         .map_seq_show_elem = htab_percpu_map_seq_show_elem,
1382 };
1383 
1384 static int fd_htab_map_alloc_check(union bpf_attr *attr)
1385 {
1386         if (attr->value_size != sizeof(u32))
1387                 return -EINVAL;
1388         return htab_map_alloc_check(attr);
1389 }
1390 
1391 static void fd_htab_map_free(struct bpf_map *map)
1392 {
1393         struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1394         struct hlist_nulls_node *n;
1395         struct hlist_nulls_head *head;
1396         struct htab_elem *l;
1397         int i;
1398 
1399         for (i = 0; i < htab->n_buckets; i++) {
1400                 head = select_bucket(htab, i);
1401 
1402                 hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
1403                         void *ptr = fd_htab_map_get_ptr(map, l);
1404 
1405                         map->ops->map_fd_put_ptr(ptr);
1406                 }
1407         }
1408 
1409         htab_map_free(map);
1410 }
1411 
1412 /* only called from syscall */
1413 int bpf_fd_htab_map_lookup_elem(struct bpf_map *map, void *key, u32 *value)
1414 {
1415         void **ptr;
1416         int ret = 0;
1417 
1418         if (!map->ops->map_fd_sys_lookup_elem)
1419                 return -ENOTSUPP;
1420 
1421         rcu_read_lock();
1422         ptr = htab_map_lookup_elem(map, key);
1423         if (ptr)
1424                 *value = map->ops->map_fd_sys_lookup_elem(READ_ONCE(*ptr));
1425         else
1426                 ret = -ENOENT;
1427         rcu_read_unlock();
1428 
1429         return ret;
1430 }
1431 
1432 /* only called from syscall */
1433 int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file,
1434                                 void *key, void *value, u64 map_flags)
1435 {
1436         void *ptr;
1437         int ret;
1438         u32 ufd = *(u32 *)value;
1439 
1440         ptr = map->ops->map_fd_get_ptr(map, map_file, ufd);
1441         if (IS_ERR(ptr))
1442                 return PTR_ERR(ptr);
1443 
1444         ret = htab_map_update_elem(map, key, &ptr, map_flags);
1445         if (ret)
1446                 map->ops->map_fd_put_ptr(ptr);
1447 
1448         return ret;
1449 }
1450 
1451 static struct bpf_map *htab_of_map_alloc(union bpf_attr *attr)
1452 {
1453         struct bpf_map *map, *inner_map_meta;
1454 
1455         inner_map_meta = bpf_map_meta_alloc(attr->inner_map_fd);
1456         if (IS_ERR(inner_map_meta))
1457                 return inner_map_meta;
1458 
1459         map = htab_map_alloc(attr);
1460         if (IS_ERR(map)) {
1461                 bpf_map_meta_free(inner_map_meta);
1462                 return map;
1463         }
1464 
1465         map->inner_map_meta = inner_map_meta;
1466 
1467         return map;
1468 }
1469 
1470 static void *htab_of_map_lookup_elem(struct bpf_map *map, void *key)
1471 {
1472         struct bpf_map **inner_map  = htab_map_lookup_elem(map, key);
1473 
1474         if (!inner_map)
1475                 return NULL;
1476 
1477         return READ_ONCE(*inner_map);
1478 }
1479 
1480 static u32 htab_of_map_gen_lookup(struct bpf_map *map,
1481                                   struct bpf_insn *insn_buf)
1482 {
1483         struct bpf_insn *insn = insn_buf;
1484         const int ret = BPF_REG_0;
1485 
1486         BUILD_BUG_ON(!__same_type(&__htab_map_lookup_elem,
1487                      (void *(*)(struct bpf_map *map, void *key))NULL));
1488         *insn++ = BPF_EMIT_CALL(BPF_CAST_CALL(__htab_map_lookup_elem));
1489         *insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 2);
1490         *insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
1491                                 offsetof(struct htab_elem, key) +
1492                                 round_up(map->key_size, 8));
1493         *insn++ = BPF_LDX_MEM(BPF_DW, ret, ret, 0);
1494 
1495         return insn - insn_buf;
1496 }
1497 
1498 static void htab_of_map_free(struct bpf_map *map)
1499 {
1500         bpf_map_meta_free(map->inner_map_meta);
1501         fd_htab_map_free(map);
1502 }
1503 
1504 const struct bpf_map_ops htab_of_maps_map_ops = {
1505         .map_alloc_check = fd_htab_map_alloc_check,
1506         .map_alloc = htab_of_map_alloc,
1507         .map_free = htab_of_map_free,
1508         .map_get_next_key = htab_map_get_next_key,
1509         .map_lookup_elem = htab_of_map_lookup_elem,
1510         .map_delete_elem = htab_map_delete_elem,
1511         .map_fd_get_ptr = bpf_map_fd_get_ptr,
1512         .map_fd_put_ptr = bpf_map_fd_put_ptr,
1513         .map_fd_sys_lookup_elem = bpf_map_fd_sys_lookup_elem,
1514         .map_gen_lookup = htab_of_map_gen_lookup,
1515         .map_check_btf = map_check_no_btf,
1516 };
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root/kernel/bpf/hashtab.c

DEFINITIONS
