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_slow_inc_cpuslocked(struct static_key *key)
  83 {
  84         int v, v1;
  85
  86         STATIC_KEY_CHECK_USE(key);
  87
  88         /*
  89          * Careful if we get concurrent static_key_slow_inc() calls;
  90          * later calls must wait for the first one to _finish_ the
  91          * jump_label_update() process.  At the same time, however,
  92          * the jump_label_update() call below wants to see
  93          * static_key_enabled(&key) for jumps to be updated properly.
  94          *
  95          * So give a special meaning to negative key->enabled: it sends
  96          * static_key_slow_inc() down the slow path, and it is non-zero
  97          * so it counts as "enabled" in jump_label_update().  Note that
  98          * atomic_inc_unless_negative() checks >= 0, so roll our own.
  99          */
 100         for (v = atomic_read(&key->enabled); v > 0; v = v1) {
 101                 v1 = atomic_cmpxchg(&key->enabled, v, v + 1);
 102                 if (likely(v1 == v))
 103                         return;
 104         }
 105
 106         jump_label_lock();
 107         if (atomic_read(&key->enabled) == 0) {
 108                 atomic_set(&key->enabled, -1);
 109                 jump_label_update(key);
 110                 /*
 111                  * Ensure that if the above cmpxchg loop observes our positive
 112                  * value, it must also observe all the text changes.
 113                  */
 114                 atomic_set_release(&key->enabled, 1);
 115         } else {
 116                 atomic_inc(&key->enabled);
 117         }
 118         jump_label_unlock();
 119 }
 120
 121 void static_key_slow_inc(struct static_key *key)
 122 {
 123         cpus_read_lock();
 124         static_key_slow_inc_cpuslocked(key);
 125         cpus_read_unlock();
 126 }
 127 EXPORT_SYMBOL_GPL(static_key_slow_inc);
 128
 129 void static_key_enable_cpuslocked(struct static_key *key)
 130 {
 131         STATIC_KEY_CHECK_USE(key);
 132
 133         if (atomic_read(&key->enabled) > 0) {
 134                 WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
 135                 return;
 136         }
 137
 138         jump_label_lock();
 139         if (atomic_read(&key->enabled) == 0) {
 140                 atomic_set(&key->enabled, -1);
 141                 jump_label_update(key);
 142                 /*
 143                  * See static_key_slow_inc().
 144                  */
 145                 atomic_set_release(&key->enabled, 1);
 146         }
 147         jump_label_unlock();
 148 }
 149 EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked);
 150
 151 void static_key_enable(struct static_key *key)
 152 {
 153         cpus_read_lock();
 154         static_key_enable_cpuslocked(key);
 155         cpus_read_unlock();
 156 }
 157 EXPORT_SYMBOL_GPL(static_key_enable);
 158
 159 void static_key_disable_cpuslocked(struct static_key *key)
 160 {
 161         STATIC_KEY_CHECK_USE(key);
 162
 163         if (atomic_read(&key->enabled) != 1) {
 164                 WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
 165                 return;
 166         }
 167
 168         jump_label_lock();
 169         if (atomic_cmpxchg(&key->enabled, 1, 0))
 170                 jump_label_update(key);
 171         jump_label_unlock();
 172 }
 173 EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked);
 174
 175 void static_key_disable(struct static_key *key)
 176 {
 177         cpus_read_lock();
 178         static_key_disable_cpuslocked(key);
 179         cpus_read_unlock();
 180 }
 181 EXPORT_SYMBOL_GPL(static_key_disable);
 182
 183 static void __static_key_slow_dec_cpuslocked(struct static_key *key,
 184                                            unsigned long rate_limit,
 185                                            struct delayed_work *work)
 186 {
 187         /*
 188          * The negative count check is valid even when a negative
 189          * key->enabled is in use by static_key_slow_inc(); a
 190          * __static_key_slow_dec() before the first static_key_slow_inc()
 191          * returns is unbalanced, because all other static_key_slow_inc()
 192          * instances block while the update is in progress.
 193          */
 194         if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) {
 195                 WARN(atomic_read(&key->enabled) < 0,
 196                      "jump label: negative count!\n");
 197                 return;
 198         }
 199
 200         if (rate_limit) {
 201                 atomic_inc(&key->enabled);
 202                 schedule_delayed_work(work, rate_limit);
 203         } else {
 204                 jump_label_update(key);
 205         }
 206         jump_label_unlock();
 207 }
 208
 209 static void __static_key_slow_dec(struct static_key *key,
 210                                   unsigned long rate_limit,
 211                                   struct delayed_work *work)
 212 {
 213         cpus_read_lock();
 214         __static_key_slow_dec_cpuslocked(key, rate_limit, work);
 215         cpus_read_unlock();
 216 }
 217
 218 static void jump_label_update_timeout(struct work_struct *work)
 219 {
 220         struct static_key_deferred *key =
 221                 container_of(work, struct static_key_deferred, work.work);
 222         __static_key_slow_dec(&key->key, 0, NULL);
 223 }
 224
 225 void static_key_slow_dec(struct static_key *key)
 226 {
 227         STATIC_KEY_CHECK_USE(key);
 228         __static_key_slow_dec(key, 0, NULL);
 229 }
 230 EXPORT_SYMBOL_GPL(static_key_slow_dec);
 231
 232 void static_key_slow_dec_cpuslocked(struct static_key *key)
 233 {
 234         STATIC_KEY_CHECK_USE(key);
 235         __static_key_slow_dec_cpuslocked(key, 0, NULL);
 236 }
 237
 238 void static_key_slow_dec_deferred(struct static_key_deferred *key)
 239 {
 240         STATIC_KEY_CHECK_USE(key);
 241         __static_key_slow_dec(&key->key, key->timeout, &key->work);
 242 }
 243 EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);
 244
 245 void static_key_deferred_flush(struct static_key_deferred *key)
 246 {
 247         STATIC_KEY_CHECK_USE(key);
 248         flush_delayed_work(&key->work);
 249 }
 250 EXPORT_SYMBOL_GPL(static_key_deferred_flush);
 251
 252 void jump_label_rate_limit(struct static_key_deferred *key,
 253                 unsigned long rl)
 254 {
 255         STATIC_KEY_CHECK_USE(key);
 256         key->timeout = rl;
 257         INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
 258 }
 259 EXPORT_SYMBOL_GPL(jump_label_rate_limit);
 260
 261 static int addr_conflict(struct jump_entry *entry, void *start, void *end)
 262 {
 263         if (entry->code <= (unsigned long)end &&
 264                 entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
 265                 return 1;
 266
 267         return 0;
 268 }
 269
 270 static int __jump_label_text_reserved(struct jump_entry *iter_start,
 271                 struct jump_entry *iter_stop, void *start, void *end)
 272 {
 273         struct jump_entry *iter;
 274
 275         iter = iter_start;
 276         while (iter < iter_stop) {
 277                 if (addr_conflict(iter, start, end))
 278                         return 1;
 279                 iter++;
 280         }
 281
 282         return 0;
 283 }
 284
 285 /*
 286  * Update code which is definitely not currently executing.
 287  * Architectures which need heavyweight synchronization to modify
 288  * running code can override this to make the non-live update case
 289  * cheaper.
 290  */
 291 void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
 292                                             enum jump_label_type type)
 293 {
 294         arch_jump_label_transform(entry, type);
 295 }
 296
 297 static inline struct jump_entry *static_key_entries(struct static_key *key)
 298 {
 299         WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED);
 300         return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK);
 301 }
 302
 303 static inline bool static_key_type(struct static_key *key)
 304 {
 305         return key->type & JUMP_TYPE_TRUE;
 306 }
 307
 308 static inline bool static_key_linked(struct static_key *key)
 309 {
 310         return key->type & JUMP_TYPE_LINKED;
 311 }
 312
 313 static inline void static_key_clear_linked(struct static_key *key)
 314 {
 315         key->type &= ~JUMP_TYPE_LINKED;
 316 }
 317
 318 static inline void static_key_set_linked(struct static_key *key)
 319 {
 320         key->type |= JUMP_TYPE_LINKED;
 321 }
 322
 323 static inline struct static_key *jump_entry_key(struct jump_entry *entry)
 324 {
 325         return (struct static_key *)((unsigned long)entry->key & ~1UL);
 326 }
 327
 328 static bool jump_entry_branch(struct jump_entry *entry)
 329 {
 330         return (unsigned long)entry->key & 1UL;
 331 }
 332
 333 /***
 334  * A 'struct static_key' uses a union such that it either points directly
 335  * to a table of 'struct jump_entry' or to a linked list of modules which in
 336  * turn point to 'struct jump_entry' tables.
 337  *
 338  * The two lower bits of the pointer are used to keep track of which pointer
 339  * type is in use and to store the initial branch direction, we use an access
 340  * function which preserves these bits.
 341  */
 342 static void static_key_set_entries(struct static_key *key,
 343                                    struct jump_entry *entries)
 344 {
 345         unsigned long type;
 346
 347         WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK);
 348         type = key->type & JUMP_TYPE_MASK;
 349         key->entries = entries;
 350         key->type |= type;
 351 }
 352
 353 static enum jump_label_type jump_label_type(struct jump_entry *entry)
 354 {
 355         struct static_key *key = jump_entry_key(entry);
 356         bool enabled = static_key_enabled(key);
 357         bool branch = jump_entry_branch(entry);
 358
 359         /* See the comment in linux/jump_label.h */
 360         return enabled ^ branch;
 361 }
 362
 363 static void __jump_label_update(struct static_key *key,
 364                                 struct jump_entry *entry,
 365                                 struct jump_entry *stop)
 366 {
 367         for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
 368                 /*
 369                  * entry->code set to 0 invalidates module init text sections
 370                  * kernel_text_address() verifies we are not in core kernel
 371                  * init code, see jump_label_invalidate_module_init().
 372                  */
 373                 if (entry->code && kernel_text_address(entry->code))
 374                         arch_jump_label_transform(entry, jump_label_type(entry));
 375         }
 376 }
 377
 378 void __init jump_label_init(void)
 379 {
 380         struct jump_entry *iter_start = __start___jump_table;
 381         struct jump_entry *iter_stop = __stop___jump_table;
 382         struct static_key *key = NULL;
 383         struct jump_entry *iter;
 384
 385         /*
 386          * Since we are initializing the static_key.enabled field with
 387          * with the 'raw' int values (to avoid pulling in atomic.h) in
 388          * jump_label.h, let's make sure that is safe. There are only two
 389          * cases to check since we initialize to 0 or 1.
 390          */
 391         BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0);
 392         BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1);
 393
 394         if (static_key_initialized)
 395                 return;
 396
 397         cpus_read_lock();
 398         jump_label_lock();
 399         jump_label_sort_entries(iter_start, iter_stop);
 400
 401         for (iter = iter_start; iter < iter_stop; iter++) {
 402                 struct static_key *iterk;
 403
 404                 /* rewrite NOPs */
 405                 if (jump_label_type(iter) == JUMP_LABEL_NOP)
 406                         arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
 407
 408                 iterk = jump_entry_key(iter);
 409                 if (iterk == key)
 410                         continue;
 411
 412                 key = iterk;
 413                 static_key_set_entries(key, iter);
 414         }
 415         static_key_initialized = true;
 416         jump_label_unlock();
 417         cpus_read_unlock();
 418 }
 419
 420 #ifdef CONFIG_MODULES
 421
 422 static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
 423 {
 424         struct static_key *key = jump_entry_key(entry);
 425         bool type = static_key_type(key);
 426         bool branch = jump_entry_branch(entry);
 427
 428         /* See the comment in linux/jump_label.h */
 429         return type ^ branch;
 430 }
 431
 432 struct static_key_mod {
 433         struct static_key_mod *next;
 434         struct jump_entry *entries;
 435         struct module *mod;
 436 };
 437
 438 static inline struct static_key_mod *static_key_mod(struct static_key *key)
 439 {
 440         WARN_ON_ONCE(!(key->type & JUMP_TYPE_LINKED));
 441         return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK);
 442 }
 443
 444 /***
 445  * key->type and key->next are the same via union.
 446  * This sets key->next and preserves the type bits.
 447  *
 448  * See additional comments above static_key_set_entries().
 449  */
 450 static void static_key_set_mod(struct static_key *key,
 451                                struct static_key_mod *mod)
 452 {
 453         unsigned long type;
 454
 455         WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK);
 456         type = key->type & JUMP_TYPE_MASK;
 457         key->next = mod;
 458         key->type |= type;
 459 }
 460
 461 static int __jump_label_mod_text_reserved(void *start, void *end)
 462 {
 463         struct module *mod;
 464
 465         preempt_disable();
 466         mod = __module_text_address((unsigned long)start);
 467         WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
 468         preempt_enable();
 469
 470         if (!mod)
 471                 return 0;
 472
 473
 474         return __jump_label_text_reserved(mod->jump_entries,
 475                                 mod->jump_entries + mod->num_jump_entries,
 476                                 start, end);
 477 }
 478
 479 static void __jump_label_mod_update(struct static_key *key)
 480 {
 481         struct static_key_mod *mod;
 482
 483         for (mod = static_key_mod(key); mod; mod = mod->next) {
 484                 struct jump_entry *stop;
 485                 struct module *m;
 486
 487                 /*
 488                  * NULL if the static_key is defined in a module
 489                  * that does not use it
 490                  */
 491                 if (!mod->entries)
 492                         continue;
 493
 494                 m = mod->mod;
 495                 if (!m)
 496                         stop = __stop___jump_table;
 497                 else
 498                         stop = m->jump_entries + m->num_jump_entries;
 499                 __jump_label_update(key, mod->entries, stop);
 500         }
 501 }
 502
 503 /***
 504  * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
 505  * @mod: module to patch
 506  *
 507  * Allow for run-time selection of the optimal nops. Before the module
 508  * loads patch these with arch_get_jump_label_nop(), which is specified by
 509  * the arch specific jump label code.
 510  */
 511 void jump_label_apply_nops(struct module *mod)
 512 {
 513         struct jump_entry *iter_start = mod->jump_entries;
 514         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
 515         struct jump_entry *iter;
 516
 517         /* if the module doesn't have jump label entries, just return */
 518         if (iter_start == iter_stop)
 519                 return;
 520
 521         for (iter = iter_start; iter < iter_stop; iter++) {
 522                 /* Only write NOPs for arch_branch_static(). */
 523                 if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
 524                         arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
 525         }
 526 }
 527
 528 static int jump_label_add_module(struct module *mod)
 529 {
 530         struct jump_entry *iter_start = mod->jump_entries;
 531         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
 532         struct jump_entry *iter;
 533         struct static_key *key = NULL;
 534         struct static_key_mod *jlm, *jlm2;
 535
 536         /* if the module doesn't have jump label entries, just return */
 537         if (iter_start == iter_stop)
 538                 return 0;
 539
 540         jump_label_sort_entries(iter_start, iter_stop);
 541
 542         for (iter = iter_start; iter < iter_stop; iter++) {
 543                 struct static_key *iterk;
 544
 545                 iterk = jump_entry_key(iter);
 546                 if (iterk == key)
 547                         continue;
 548
 549                 key = iterk;
 550                 if (within_module(iter->key, mod)) {
 551                         static_key_set_entries(key, iter);
 552                         continue;
 553                 }
 554                 jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
 555                 if (!jlm)
 556                         return -ENOMEM;
 557                 if (!static_key_linked(key)) {
 558                         jlm2 = kzalloc(sizeof(struct static_key_mod),
 559                                        GFP_KERNEL);
 560                         if (!jlm2) {
 561                                 kfree(jlm);
 562                                 return -ENOMEM;
 563                         }
 564                         preempt_disable();
 565                         jlm2->mod = __module_address((unsigned long)key);
 566                         preempt_enable();
 567                         jlm2->entries = static_key_entries(key);
 568                         jlm2->next = NULL;
 569                         static_key_set_mod(key, jlm2);
 570                         static_key_set_linked(key);
 571                 }
 572                 jlm->mod = mod;
 573                 jlm->entries = iter;
 574                 jlm->next = static_key_mod(key);
 575                 static_key_set_mod(key, jlm);
 576                 static_key_set_linked(key);
 577
 578                 /* Only update if we've changed from our initial state */
 579                 if (jump_label_type(iter) != jump_label_init_type(iter))
 580                         __jump_label_update(key, iter, iter_stop);
 581         }
 582
 583         return 0;
 584 }
 585
 586 static void jump_label_del_module(struct module *mod)
 587 {
 588         struct jump_entry *iter_start = mod->jump_entries;
 589         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
 590         struct jump_entry *iter;
 591         struct static_key *key = NULL;
 592         struct static_key_mod *jlm, **prev;
 593
 594         for (iter = iter_start; iter < iter_stop; iter++) {
 595                 if (jump_entry_key(iter) == key)
 596                         continue;
 597
 598                 key = jump_entry_key(iter);
 599
 600                 if (within_module(iter->key, mod))
 601                         continue;
 602
 603                 /* No memory during module load */
 604                 if (WARN_ON(!static_key_linked(key)))
 605                         continue;
 606
 607                 prev = &key->next;
 608                 jlm = static_key_mod(key);
 609
 610                 while (jlm && jlm->mod != mod) {
 611                         prev = &jlm->next;
 612                         jlm = jlm->next;
 613                 }
 614
 615                 /* No memory during module load */
 616                 if (WARN_ON(!jlm))
 617                         continue;
 618
 619                 if (prev == &key->next)
 620                         static_key_set_mod(key, jlm->next);
 621                 else
 622                         *prev = jlm->next;
 623
 624                 kfree(jlm);
 625
 626                 jlm = static_key_mod(key);
 627                 /* if only one etry is left, fold it back into the static_key */
 628                 if (jlm->next == NULL) {
 629                         static_key_set_entries(key, jlm->entries);
 630                         static_key_clear_linked(key);
 631                         kfree(jlm);
 632                 }
 633         }
 634 }
 635
 636 static void jump_label_invalidate_module_init(struct module *mod)
 637 {
 638         struct jump_entry *iter_start = mod->jump_entries;
 639         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
 640         struct jump_entry *iter;
 641
 642         for (iter = iter_start; iter < iter_stop; iter++) {
 643                 if (within_module_init(iter->code, mod))
 644                         iter->code = 0;
 645         }
 646 }
 647
 648 static int
 649 jump_label_module_notify(struct notifier_block *self, unsigned long val,
 650                          void *data)
 651 {
 652         struct module *mod = data;
 653         int ret = 0;
 654
 655         cpus_read_lock();
 656         jump_label_lock();
 657
 658         switch (val) {
 659         case MODULE_STATE_COMING:
 660                 ret = jump_label_add_module(mod);
 661                 if (ret) {
 662                         WARN(1, "Failed to allocatote memory: jump_label may not work properly.\n");
 663                         jump_label_del_module(mod);
 664                 }
 665                 break;
 666         case MODULE_STATE_GOING:
 667                 jump_label_del_module(mod);
 668                 break;
 669         case MODULE_STATE_LIVE:
 670                 jump_label_invalidate_module_init(mod);
 671                 break;
 672         }
 673
 674         jump_label_unlock();
 675         cpus_read_unlock();
 676
 677         return notifier_from_errno(ret);
 678 }
 679
 680 static struct notifier_block jump_label_module_nb = {
 681         .notifier_call = jump_label_module_notify,
 682         .priority = 1, /* higher than tracepoints */
 683 };
 684
 685 static __init int jump_label_init_module(void)
 686 {
 687         return register_module_notifier(&jump_label_module_nb);
 688 }
 689 early_initcall(jump_label_init_module);
 690
 691 #endif /* CONFIG_MODULES */
 692
 693 /***
 694  * jump_label_text_reserved - check if addr range is reserved
 695  * @start: start text addr
 696  * @end: end text addr
 697  *
 698  * checks if the text addr located between @start and @end
 699  * overlaps with any of the jump label patch addresses. Code
 700  * that wants to modify kernel text should first verify that
 701  * it does not overlap with any of the jump label addresses.
 702  * Caller must hold jump_label_mutex.
 703  *
 704  * returns 1 if there is an overlap, 0 otherwise
 705  */
 706 int jump_label_text_reserved(void *start, void *end)
 707 {
 708         int ret = __jump_label_text_reserved(__start___jump_table,
 709                         __stop___jump_table, start, end);
 710
 711         if (ret)
 712                 return ret;
 713
 714 #ifdef CONFIG_MODULES
 715         ret = __jump_label_mod_text_reserved(start, end);
 716 #endif
 717         return ret;
 718 }
 719
 720 static void jump_label_update(struct static_key *key)
 721 {
 722         struct jump_entry *stop = __stop___jump_table;
 723         struct jump_entry *entry;
 724 #ifdef CONFIG_MODULES
 725         struct module *mod;
 726
 727         if (static_key_linked(key)) {
 728                 __jump_label_mod_update(key);
 729                 return;
 730         }
 731
 732         preempt_disable();
 733         mod = __module_address((unsigned long)key);
 734         if (mod)
 735                 stop = mod->jump_entries + mod->num_jump_entries;
 736         preempt_enable();
 737 #endif
 738         entry = static_key_entries(key);
 739         /* if there are no users, entry can be NULL */
 740         if (entry)
 741                 __jump_label_update(key, entry, stop);
 742 }
 743
 744 #ifdef CONFIG_STATIC_KEYS_SELFTEST
 745 static DEFINE_STATIC_KEY_TRUE(sk_true);
 746 static DEFINE_STATIC_KEY_FALSE(sk_false);
 747
 748 static __init int jump_label_test(void)
 749 {
 750         int i;
 751
 752         for (i = 0; i < 2; i++) {
 753                 WARN_ON(static_key_enabled(&sk_true.key) != true);
 754                 WARN_ON(static_key_enabled(&sk_false.key) != false);
 755
 756                 WARN_ON(!static_branch_likely(&sk_true));
 757                 WARN_ON(!static_branch_unlikely(&sk_true));
 758                 WARN_ON(static_branch_likely(&sk_false));
 759                 WARN_ON(static_branch_unlikely(&sk_false));
 760
 761                 static_branch_disable(&sk_true);
 762                 static_branch_enable(&sk_false);
 763
 764                 WARN_ON(static_key_enabled(&sk_true.key) == true);
 765                 WARN_ON(static_key_enabled(&sk_false.key) == false);
 766
 767                 WARN_ON(static_branch_likely(&sk_true));
 768                 WARN_ON(static_branch_unlikely(&sk_true));
 769                 WARN_ON(!static_branch_likely(&sk_false));
 770                 WARN_ON(!static_branch_unlikely(&sk_false));
 771
 772                 static_branch_enable(&sk_true);
 773                 static_branch_disable(&sk_false);
 774         }
 775
 776         return 0;
 777 }
 778 early_initcall(jump_label_test);
 779 #endif /* STATIC_KEYS_SELFTEST */
 780
 781 #endif /* HAVE_JUMP_LABEL */