kernel/jump_label.c

   1 /*
   2  * jump label support
   3  *
   4  * Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
   5  * Copyright (C) 2011 Peter Zijlstra
   6  *
   7  */
   8 #include <linux/memory.h>
   9 #include <linux/uaccess.h>
  10 #include <linux/module.h>
  11 #include <linux/list.h>
  12 #include <linux/slab.h>
  13 #include <linux/sort.h>
  14 #include <linux/err.h>
  15 #include <linux/static_key.h>
  16 #include <linux/jump_label_ratelimit.h>
  17 #include <linux/bug.h>
  18 #include <linux/cpu.h>
  19
  20 #ifdef HAVE_JUMP_LABEL
  21
  22 /* mutex to protect coming/going of the the jump_label table */
  23 static DEFINE_MUTEX(jump_label_mutex);
  24
  25 void jump_label_lock(void)
  26 {
  27         mutex_lock(&jump_label_mutex);
  28 }
  29
  30 void jump_label_unlock(void)
  31 {
  32         mutex_unlock(&jump_label_mutex);
  33 }
  34
  35 static int jump_label_cmp(const void *a, const void *b)
  36 {
  37         const struct jump_entry *jea = a;
  38         const struct jump_entry *jeb = b;
  39
  40         if (jea->key < jeb->key)
  41                 return -1;
  42
  43         if (jea->key > jeb->key)
  44                 return 1;
  45
  46         return 0;
  47 }
  48
  49 static void
  50 jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
  51 {
  52         unsigned long size;
  53
  54         size = (((unsigned long)stop - (unsigned long)start)
  55                                         / sizeof(struct jump_entry));
  56         sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
  57 }
  58
  59 static void jump_label_update(struct static_key *key);
  60
  61 /*
  62  * There are similar definitions for the !HAVE_JUMP_LABEL case in jump_label.h.
  63  * The use of 'atomic_read()' requires atomic.h and its problematic for some
  64  * kernel headers such as kernel.h and others. Since static_key_count() is not
  65  * used in the branch statements as it is for the !HAVE_JUMP_LABEL case its ok
  66  * to have it be a function here. Similarly, for 'static_key_enable()' and
  67  * 'static_key_disable()', which require bug.h. This should allow jump_label.h
  68  * to be included from most/all places for HAVE_JUMP_LABEL.
  69  */
  70 int static_key_count(struct static_key *key)
  71 {
  72         /*
  73          * -1 means the first static_key_slow_inc() is in progress.
  74          *  static_key_enabled() must return true, so return 1 here.
  75          */
  76         int n = atomic_read(&key->enabled);
  77
  78         return n >= 0 ? n : 1;
  79 }
  80 EXPORT_SYMBOL_GPL(static_key_count);
  81
  82 void static_key_enable(struct static_key *key)
  83 {
  84         int count = static_key_count(key);
  85
  86         WARN_ON_ONCE(count < 0 || count > 1);
  87
  88         if (!count)
  89                 static_key_slow_inc(key);
  90 }
  91 EXPORT_SYMBOL_GPL(static_key_enable);
  92
  93 void static_key_disable(struct static_key *key)
  94 {
  95         int count = static_key_count(key);
  96
  97         WARN_ON_ONCE(count < 0 || count > 1);
  98
  99         if (count)
 100                 static_key_slow_dec(key);
 101 }
 102 EXPORT_SYMBOL_GPL(static_key_disable);
 103
 104 void static_key_slow_inc(struct static_key *key)
 105 {
 106         int v, v1;
 107
 108         STATIC_KEY_CHECK_USE();
 109
 110         /*
 111          * Careful if we get concurrent static_key_slow_inc() calls;
 112          * later calls must wait for the first one to _finish_ the
 113          * jump_label_update() process.  At the same time, however,
 114          * the jump_label_update() call below wants to see
 115          * static_key_enabled(&key) for jumps to be updated properly.
 116          *
 117          * So give a special meaning to negative key->enabled: it sends
 118          * static_key_slow_inc() down the slow path, and it is non-zero
 119          * so it counts as "enabled" in jump_label_update().  Note that
 120          * atomic_inc_unless_negative() checks >= 0, so roll our own.
 121          */
 122         for (v = atomic_read(&key->enabled); v > 0; v = v1) {
 123                 v1 = atomic_cmpxchg(&key->enabled, v, v + 1);
 124                 if (likely(v1 == v))
 125                         return;
 126         }
 127
 128         cpus_read_lock();
 129         jump_label_lock();
 130         if (atomic_read(&key->enabled) == 0) {
 131                 atomic_set(&key->enabled, -1);
 132                 jump_label_update(key);
 133                 atomic_set(&key->enabled, 1);
 134         } else {
 135                 atomic_inc(&key->enabled);
 136         }
 137         jump_label_unlock();
 138         cpus_read_unlock();
 139 }
 140 EXPORT_SYMBOL_GPL(static_key_slow_inc);
 141
 142 static void __static_key_slow_dec(struct static_key *key,
 143                 unsigned long rate_limit, struct delayed_work *work)
 144 {
 145         cpus_read_lock();
 146         /*
 147          * The negative count check is valid even when a negative
 148          * key->enabled is in use by static_key_slow_inc(); a
 149          * __static_key_slow_dec() before the first static_key_slow_inc()
 150          * returns is unbalanced, because all other static_key_slow_inc()
 151          * instances block while the update is in progress.
 152          */
 153         if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) {
 154                 WARN(atomic_read(&key->enabled) < 0,
 155                      "jump label: negative count!\n");
 156                 cpus_read_unlock();
 157                 return;
 158         }
 159
 160         if (rate_limit) {
 161                 atomic_inc(&key->enabled);
 162                 schedule_delayed_work(work, rate_limit);
 163         } else {
 164                 jump_label_update(key);
 165         }
 166         jump_label_unlock();
 167         cpus_read_unlock();
 168 }
 169
 170 static void jump_label_update_timeout(struct work_struct *work)
 171 {
 172         struct static_key_deferred *key =
 173                 container_of(work, struct static_key_deferred, work.work);
 174         __static_key_slow_dec(&key->key, 0, NULL);
 175 }
 176
 177 void static_key_slow_dec(struct static_key *key)
 178 {
 179         STATIC_KEY_CHECK_USE();
 180         __static_key_slow_dec(key, 0, NULL);
 181 }
 182 EXPORT_SYMBOL_GPL(static_key_slow_dec);
 183
 184 void static_key_slow_dec_deferred(struct static_key_deferred *key)
 185 {
 186         STATIC_KEY_CHECK_USE();
 187         __static_key_slow_dec(&key->key, key->timeout, &key->work);
 188 }
 189 EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);
 190
 191 void static_key_deferred_flush(struct static_key_deferred *key)
 192 {
 193         STATIC_KEY_CHECK_USE();
 194         flush_delayed_work(&key->work);
 195 }
 196 EXPORT_SYMBOL_GPL(static_key_deferred_flush);
 197
 198 void jump_label_rate_limit(struct static_key_deferred *key,
 199                 unsigned long rl)
 200 {
 201         STATIC_KEY_CHECK_USE();
 202         key->timeout = rl;
 203         INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
 204 }
 205 EXPORT_SYMBOL_GPL(jump_label_rate_limit);
 206
 207 static int addr_conflict(struct jump_entry *entry, void *start, void *end)
 208 {
 209         if (entry->code <= (unsigned long)end &&
 210                 entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
 211                 return 1;
 212
 213         return 0;
 214 }
 215
 216 static int __jump_label_text_reserved(struct jump_entry *iter_start,
 217                 struct jump_entry *iter_stop, void *start, void *end)
 218 {
 219         struct jump_entry *iter;
 220
 221         iter = iter_start;
 222         while (iter < iter_stop) {
 223                 if (addr_conflict(iter, start, end))
 224                         return 1;
 225                 iter++;
 226         }
 227
 228         return 0;
 229 }
 230
 231 /*
 232  * Update code which is definitely not currently executing.
 233  * Architectures which need heavyweight synchronization to modify
 234  * running code can override this to make the non-live update case
 235  * cheaper.
 236  */
 237 void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
 238                                             enum jump_label_type type)
 239 {
 240         arch_jump_label_transform(entry, type);
 241 }
 242
 243 static inline struct jump_entry *static_key_entries(struct static_key *key)
 244 {
 245         WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED);
 246         return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK);
 247 }
 248
 249 static inline bool static_key_type(struct static_key *key)
 250 {
 251         return key->type & JUMP_TYPE_TRUE;
 252 }
 253
 254 static inline bool static_key_linked(struct static_key *key)
 255 {
 256         return key->type & JUMP_TYPE_LINKED;
 257 }
 258
 259 static inline void static_key_clear_linked(struct static_key *key)
 260 {
 261         key->type &= ~JUMP_TYPE_LINKED;
 262 }
 263
 264 static inline void static_key_set_linked(struct static_key *key)
 265 {
 266         key->type |= JUMP_TYPE_LINKED;
 267 }
 268
 269 static inline struct static_key *jump_entry_key(struct jump_entry *entry)
 270 {
 271         return (struct static_key *)((unsigned long)entry->key & ~1UL);
 272 }
 273
 274 static bool jump_entry_branch(struct jump_entry *entry)
 275 {
 276         return (unsigned long)entry->key & 1UL;
 277 }
 278
 279 /***
 280  * A 'struct static_key' uses a union such that it either points directly
 281  * to a table of 'struct jump_entry' or to a linked list of modules which in
 282  * turn point to 'struct jump_entry' tables.
 283  *
 284  * The two lower bits of the pointer are used to keep track of which pointer
 285  * type is in use and to store the initial branch direction, we use an access
 286  * function which preserves these bits.
 287  */
 288 static void static_key_set_entries(struct static_key *key,
 289                                    struct jump_entry *entries)
 290 {
 291         unsigned long type;
 292
 293         WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK);
 294         type = key->type & JUMP_TYPE_MASK;
 295         key->entries = entries;
 296         key->type |= type;
 297 }
 298
 299 static enum jump_label_type jump_label_type(struct jump_entry *entry)
 300 {
 301         struct static_key *key = jump_entry_key(entry);
 302         bool enabled = static_key_enabled(key);
 303         bool branch = jump_entry_branch(entry);
 304
 305         /* See the comment in linux/jump_label.h */
 306         return enabled ^ branch;
 307 }
 308
 309 static void __jump_label_update(struct static_key *key,
 310                                 struct jump_entry *entry,
 311                                 struct jump_entry *stop)
 312 {
 313         for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
 314                 /*
 315                  * entry->code set to 0 invalidates module init text sections
 316                  * kernel_text_address() verifies we are not in core kernel
 317                  * init code, see jump_label_invalidate_module_init().
 318                  */
 319                 if (entry->code && kernel_text_address(entry->code))
 320                         arch_jump_label_transform(entry, jump_label_type(entry));
 321         }
 322 }
 323
 324 void __init jump_label_init(void)
 325 {
 326         struct jump_entry *iter_start = __start___jump_table;
 327         struct jump_entry *iter_stop = __stop___jump_table;
 328         struct static_key *key = NULL;
 329         struct jump_entry *iter;
 330
 331         /*
 332          * Since we are initializing the static_key.enabled field with
 333          * with the 'raw' int values (to avoid pulling in atomic.h) in
 334          * jump_label.h, let's make sure that is safe. There are only two
 335          * cases to check since we initialize to 0 or 1.
 336          */
 337         BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0);
 338         BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1);
 339
 340         if (static_key_initialized)
 341                 return;
 342
 343         cpus_read_lock();
 344         jump_label_lock();
 345         jump_label_sort_entries(iter_start, iter_stop);
 346
 347         for (iter = iter_start; iter < iter_stop; iter++) {
 348                 struct static_key *iterk;
 349
 350                 /* rewrite NOPs */
 351                 if (jump_label_type(iter) == JUMP_LABEL_NOP)
 352                         arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
 353
 354                 iterk = jump_entry_key(iter);
 355                 if (iterk == key)
 356                         continue;
 357
 358                 key = iterk;
 359                 static_key_set_entries(key, iter);
 360         }
 361         static_key_initialized = true;
 362         jump_label_unlock();
 363         cpus_read_unlock();
 364 }
 365
 366 #ifdef CONFIG_MODULES
 367
 368 static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
 369 {
 370         struct static_key *key = jump_entry_key(entry);
 371         bool type = static_key_type(key);
 372         bool branch = jump_entry_branch(entry);
 373
 374         /* See the comment in linux/jump_label.h */
 375         return type ^ branch;
 376 }
 377
 378 struct static_key_mod {
 379         struct static_key_mod *next;
 380         struct jump_entry *entries;
 381         struct module *mod;
 382 };
 383
 384 static inline struct static_key_mod *static_key_mod(struct static_key *key)
 385 {
 386         WARN_ON_ONCE(!(key->type & JUMP_TYPE_LINKED));
 387         return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK);
 388 }
 389
 390 /***
 391  * key->type and key->next are the same via union.
 392  * This sets key->next and preserves the type bits.
 393  *
 394  * See additional comments above static_key_set_entries().
 395  */
 396 static void static_key_set_mod(struct static_key *key,
 397                                struct static_key_mod *mod)
 398 {
 399         unsigned long type;
 400
 401         WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK);
 402         type = key->type & JUMP_TYPE_MASK;
 403         key->next = mod;
 404         key->type |= type;
 405 }
 406
 407 static int __jump_label_mod_text_reserved(void *start, void *end)
 408 {
 409         struct module *mod;
 410
 411         preempt_disable();
 412         mod = __module_text_address((unsigned long)start);
 413         WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
 414         preempt_enable();
 415
 416         if (!mod)
 417                 return 0;
 418
 419
 420         return __jump_label_text_reserved(mod->jump_entries,
 421                                 mod->jump_entries + mod->num_jump_entries,
 422                                 start, end);
 423 }
 424
 425 static void __jump_label_mod_update(struct static_key *key)
 426 {
 427         struct static_key_mod *mod;
 428
 429         for (mod = static_key_mod(key); mod; mod = mod->next) {
 430                 struct jump_entry *stop;
 431                 struct module *m;
 432
 433                 /*
 434                  * NULL if the static_key is defined in a module
 435                  * that does not use it
 436                  */
 437                 if (!mod->entries)
 438                         continue;
 439
 440                 m = mod->mod;
 441                 if (!m)
 442                         stop = __stop___jump_table;
 443                 else
 444                         stop = m->jump_entries + m->num_jump_entries;
 445                 __jump_label_update(key, mod->entries, stop);
 446         }
 447 }
 448
 449 /***
 450  * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
 451  * @mod: module to patch
 452  *
 453  * Allow for run-time selection of the optimal nops. Before the module
 454  * loads patch these with arch_get_jump_label_nop(), which is specified by
 455  * the arch specific jump label code.
 456  */
 457 void jump_label_apply_nops(struct module *mod)
 458 {
 459         struct jump_entry *iter_start = mod->jump_entries;
 460         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
 461         struct jump_entry *iter;
 462
 463         /* if the module doesn't have jump label entries, just return */
 464         if (iter_start == iter_stop)
 465                 return;
 466
 467         for (iter = iter_start; iter < iter_stop; iter++) {
 468                 /* Only write NOPs for arch_branch_static(). */
 469                 if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
 470                         arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
 471         }
 472 }
 473
 474 static int jump_label_add_module(struct module *mod)
 475 {
 476         struct jump_entry *iter_start = mod->jump_entries;
 477         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
 478         struct jump_entry *iter;
 479         struct static_key *key = NULL;
 480         struct static_key_mod *jlm, *jlm2;
 481
 482         /* if the module doesn't have jump label entries, just return */
 483         if (iter_start == iter_stop)
 484                 return 0;
 485
 486         jump_label_sort_entries(iter_start, iter_stop);
 487
 488         for (iter = iter_start; iter < iter_stop; iter++) {
 489                 struct static_key *iterk;
 490
 491                 iterk = jump_entry_key(iter);
 492                 if (iterk == key)
 493                         continue;
 494
 495                 key = iterk;
 496                 if (within_module(iter->key, mod)) {
 497                         static_key_set_entries(key, iter);
 498                         continue;
 499                 }
 500                 jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
 501                 if (!jlm)
 502                         return -ENOMEM;
 503                 if (!static_key_linked(key)) {
 504                         jlm2 = kzalloc(sizeof(struct static_key_mod),
 505                                        GFP_KERNEL);
 506                         if (!jlm2) {
 507                                 kfree(jlm);
 508                                 return -ENOMEM;
 509                         }
 510                         preempt_disable();
 511                         jlm2->mod = __module_address((unsigned long)key);
 512                         preempt_enable();
 513                         jlm2->entries = static_key_entries(key);
 514                         jlm2->next = NULL;
 515                         static_key_set_mod(key, jlm2);
 516                         static_key_set_linked(key);
 517                 }
 518                 jlm->mod = mod;
 519                 jlm->entries = iter;
 520                 jlm->next = static_key_mod(key);
 521                 static_key_set_mod(key, jlm);
 522                 static_key_set_linked(key);
 523
 524                 /* Only update if we've changed from our initial state */
 525                 if (jump_label_type(iter) != jump_label_init_type(iter))
 526                         __jump_label_update(key, iter, iter_stop);
 527         }
 528
 529         return 0;
 530 }
 531
 532 static void jump_label_del_module(struct module *mod)
 533 {
 534         struct jump_entry *iter_start = mod->jump_entries;
 535         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
 536         struct jump_entry *iter;
 537         struct static_key *key = NULL;
 538         struct static_key_mod *jlm, **prev;
 539
 540         for (iter = iter_start; iter < iter_stop; iter++) {
 541                 if (jump_entry_key(iter) == key)
 542                         continue;
 543
 544                 key = jump_entry_key(iter);
 545
 546                 if (within_module(iter->key, mod))
 547                         continue;
 548
 549                 /* No memory during module load */
 550                 if (WARN_ON(!static_key_linked(key)))
 551                         continue;
 552
 553                 prev = &key->next;
 554                 jlm = static_key_mod(key);
 555
 556                 while (jlm && jlm->mod != mod) {
 557                         prev = &jlm->next;
 558                         jlm = jlm->next;
 559                 }
 560
 561                 /* No memory during module load */
 562                 if (WARN_ON(!jlm))
 563                         continue;
 564
 565                 if (prev == &key->next)
 566                         static_key_set_mod(key, jlm->next);
 567                 else
 568                         *prev = jlm->next;
 569
 570                 kfree(jlm);
 571
 572                 jlm = static_key_mod(key);
 573                 /* if only one etry is left, fold it back into the static_key */
 574                 if (jlm->next == NULL) {
 575                         static_key_set_entries(key, jlm->entries);
 576                         static_key_clear_linked(key);
 577                         kfree(jlm);
 578                 }
 579         }
 580 }
 581
 582 static void jump_label_invalidate_module_init(struct module *mod)
 583 {
 584         struct jump_entry *iter_start = mod->jump_entries;
 585         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
 586         struct jump_entry *iter;
 587
 588         for (iter = iter_start; iter < iter_stop; iter++) {
 589                 if (within_module_init(iter->code, mod))
 590                         iter->code = 0;
 591         }
 592 }
 593
 594 static int
 595 jump_label_module_notify(struct notifier_block *self, unsigned long val,
 596                          void *data)
 597 {
 598         struct module *mod = data;
 599         int ret = 0;
 600
 601         cpus_read_lock();
 602         jump_label_lock();
 603
 604         switch (val) {
 605         case MODULE_STATE_COMING:
 606                 ret = jump_label_add_module(mod);
 607                 if (ret) {
 608                         WARN(1, "Failed to allocatote memory: jump_label may not work properly.\n");
 609                         jump_label_del_module(mod);
 610                 }
 611                 break;
 612         case MODULE_STATE_GOING:
 613                 jump_label_del_module(mod);
 614                 break;
 615         case MODULE_STATE_LIVE:
 616                 jump_label_invalidate_module_init(mod);
 617                 break;
 618         }
 619
 620         jump_label_unlock();
 621         cpus_read_unlock();
 622
 623         return notifier_from_errno(ret);
 624 }
 625
 626 static struct notifier_block jump_label_module_nb = {
 627         .notifier_call = jump_label_module_notify,
 628         .priority = 1, /* higher than tracepoints */
 629 };
 630
 631 static __init int jump_label_init_module(void)
 632 {
 633         return register_module_notifier(&jump_label_module_nb);
 634 }
 635 early_initcall(jump_label_init_module);
 636
 637 #endif /* CONFIG_MODULES */
 638
 639 /***
 640  * jump_label_text_reserved - check if addr range is reserved
 641  * @start: start text addr
 642  * @end: end text addr
 643  *
 644  * checks if the text addr located between @start and @end
 645  * overlaps with any of the jump label patch addresses. Code
 646  * that wants to modify kernel text should first verify that
 647  * it does not overlap with any of the jump label addresses.
 648  * Caller must hold jump_label_mutex.
 649  *
 650  * returns 1 if there is an overlap, 0 otherwise
 651  */
 652 int jump_label_text_reserved(void *start, void *end)
 653 {
 654         int ret = __jump_label_text_reserved(__start___jump_table,
 655                         __stop___jump_table, start, end);
 656
 657         if (ret)
 658                 return ret;
 659
 660 #ifdef CONFIG_MODULES
 661         ret = __jump_label_mod_text_reserved(start, end);
 662 #endif
 663         return ret;
 664 }
 665
 666 static void jump_label_update(struct static_key *key)
 667 {
 668         struct jump_entry *stop = __stop___jump_table;
 669         struct jump_entry *entry;
 670 #ifdef CONFIG_MODULES
 671         struct module *mod;
 672
 673         if (static_key_linked(key)) {
 674                 __jump_label_mod_update(key);
 675                 return;
 676         }
 677
 678         preempt_disable();
 679         mod = __module_address((unsigned long)key);
 680         if (mod)
 681                 stop = mod->jump_entries + mod->num_jump_entries;
 682         preempt_enable();
 683 #endif
 684         entry = static_key_entries(key);
 685         /* if there are no users, entry can be NULL */
 686         if (entry)
 687                 __jump_label_update(key, entry, stop);
 688 }
 689
 690 #ifdef CONFIG_STATIC_KEYS_SELFTEST
 691 static DEFINE_STATIC_KEY_TRUE(sk_true);
 692 static DEFINE_STATIC_KEY_FALSE(sk_false);
 693
 694 static __init int jump_label_test(void)
 695 {
 696         int i;
 697
 698         for (i = 0; i < 2; i++) {
 699                 WARN_ON(static_key_enabled(&sk_true.key) != true);
 700                 WARN_ON(static_key_enabled(&sk_false.key) != false);
 701
 702                 WARN_ON(!static_branch_likely(&sk_true));
 703                 WARN_ON(!static_branch_unlikely(&sk_true));
 704                 WARN_ON(static_branch_likely(&sk_false));
 705                 WARN_ON(static_branch_unlikely(&sk_false));
 706
 707                 static_branch_disable(&sk_true);
 708                 static_branch_enable(&sk_false);
 709
 710                 WARN_ON(static_key_enabled(&sk_true.key) == true);
 711                 WARN_ON(static_key_enabled(&sk_false.key) == false);
 712
 713                 WARN_ON(static_branch_likely(&sk_true));
 714                 WARN_ON(static_branch_unlikely(&sk_true));
 715                 WARN_ON(!static_branch_likely(&sk_false));
 716                 WARN_ON(!static_branch_unlikely(&sk_false));
 717
 718                 static_branch_enable(&sk_true);
 719                 static_branch_disable(&sk_false);
 720         }
 721
 722         return 0;
 723 }
 724 late_initcall(jump_label_test);
 725 #endif /* STATIC_KEYS_SELFTEST */
 726
 727 #endif /* HAVE_JUMP_LABEL */