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 #include <asm/sections.h>
  20
  21 #ifdef HAVE_JUMP_LABEL
  22
  23 /* mutex to protect coming/going of the the jump_label table */
  24 static DEFINE_MUTEX(jump_label_mutex);
  25
  26 void jump_label_lock(void)
  27 {
  28         mutex_lock(&jump_label_mutex);
  29 }
  30
  31 void jump_label_unlock(void)
  32 {
  33         mutex_unlock(&jump_label_mutex);
  34 }
  35
  36 static int jump_label_cmp(const void *a, const void *b)
  37 {
  38         const struct jump_entry *jea = a;
  39         const struct jump_entry *jeb = b;
  40
  41         if (jea->key < jeb->key)
  42                 return -1;
  43
  44         if (jea->key > jeb->key)
  45                 return 1;
  46
  47         return 0;
  48 }
  49
  50 static void
  51 jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
  52 {
  53         unsigned long size;
  54
  55         size = (((unsigned long)stop - (unsigned long)start)
  56                                         / sizeof(struct jump_entry));
  57         sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
  58 }
  59
  60 static void jump_label_update(struct static_key *key);
  61
  62 /*
  63  * There are similar definitions for the !HAVE_JUMP_LABEL case in jump_label.h.
  64  * The use of 'atomic_read()' requires atomic.h and its problematic for some
  65  * kernel headers such as kernel.h and others. Since static_key_count() is not
  66  * used in the branch statements as it is for the !HAVE_JUMP_LABEL case its ok
  67  * to have it be a function here. Similarly, for 'static_key_enable()' and
  68  * 'static_key_disable()', which require bug.h. This should allow jump_label.h
  69  * to be included from most/all places for HAVE_JUMP_LABEL.
  70  */
  71 int static_key_count(struct static_key *key)
  72 {
  73         /*
  74          * -1 means the first static_key_slow_inc() is in progress.
  75          *  static_key_enabled() must return true, so return 1 here.
  76          */
  77         int n = atomic_read(&key->enabled);
  78
  79         return n >= 0 ? n : 1;
  80 }
  81 EXPORT_SYMBOL_GPL(static_key_count);
  82
  83 void static_key_slow_inc_cpuslocked(struct static_key *key)
  84 {
  85         int v, v1;
  86
  87         STATIC_KEY_CHECK_USE(key);
  88
  89         /*
  90          * Careful if we get concurrent static_key_slow_inc() calls;
  91          * later calls must wait for the first one to _finish_ the
  92          * jump_label_update() process.  At the same time, however,
  93          * the jump_label_update() call below wants to see
  94          * static_key_enabled(&key) for jumps to be updated properly.
  95          *
  96          * So give a special meaning to negative key->enabled: it sends
  97          * static_key_slow_inc() down the slow path, and it is non-zero
  98          * so it counts as "enabled" in jump_label_update().  Note that
  99          * atomic_inc_unless_negative() checks >= 0, so roll our own.
 100          */
 101         for (v = atomic_read(&key->enabled); v > 0; v = v1) {
 102                 v1 = atomic_cmpxchg(&key->enabled, v, v + 1);
 103                 if (likely(v1 == v))
 104                         return;
 105         }
 106
 107         jump_label_lock();
 108         if (atomic_read(&key->enabled) == 0) {
 109                 atomic_set(&key->enabled, -1);
 110                 jump_label_update(key);
 111                 /*
 112                  * Ensure that if the above cmpxchg loop observes our positive
 113                  * value, it must also observe all the text changes.
 114                  */
 115                 atomic_set_release(&key->enabled, 1);
 116         } else {
 117                 atomic_inc(&key->enabled);
 118         }
 119         jump_label_unlock();
 120 }
 121
 122 void static_key_slow_inc(struct static_key *key)
 123 {
 124         cpus_read_lock();
 125         static_key_slow_inc_cpuslocked(key);
 126         cpus_read_unlock();
 127 }
 128 EXPORT_SYMBOL_GPL(static_key_slow_inc);
 129
 130 void static_key_enable_cpuslocked(struct static_key *key)
 131 {
 132         STATIC_KEY_CHECK_USE(key);
 133
 134         if (atomic_read(&key->enabled) > 0) {
 135                 WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
 136                 return;
 137         }
 138
 139         jump_label_lock();
 140         if (atomic_read(&key->enabled) == 0) {
 141                 atomic_set(&key->enabled, -1);
 142                 jump_label_update(key);
 143                 /*
 144                  * See static_key_slow_inc().
 145                  */
 146                 atomic_set_release(&key->enabled, 1);
 147         }
 148         jump_label_unlock();
 149 }
 150 EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked);
 151
 152 void static_key_enable(struct static_key *key)
 153 {
 154         cpus_read_lock();
 155         static_key_enable_cpuslocked(key);
 156         cpus_read_unlock();
 157 }
 158 EXPORT_SYMBOL_GPL(static_key_enable);
 159
 160 void static_key_disable_cpuslocked(struct static_key *key)
 161 {
 162         STATIC_KEY_CHECK_USE(key);
 163
 164         if (atomic_read(&key->enabled) != 1) {
 165                 WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
 166                 return;
 167         }
 168
 169         jump_label_lock();
 170         if (atomic_cmpxchg(&key->enabled, 1, 0))
 171                 jump_label_update(key);
 172         jump_label_unlock();
 173 }
 174 EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked);
 175
 176 void static_key_disable(struct static_key *key)
 177 {
 178         cpus_read_lock();
 179         static_key_disable_cpuslocked(key);
 180         cpus_read_unlock();
 181 }
 182 EXPORT_SYMBOL_GPL(static_key_disable);
 183
 184 static void __static_key_slow_dec_cpuslocked(struct static_key *key,
 185                                            unsigned long rate_limit,
 186                                            struct delayed_work *work)
 187 {
 188         /*
 189          * The negative count check is valid even when a negative
 190          * key->enabled is in use by static_key_slow_inc(); a
 191          * __static_key_slow_dec() before the first static_key_slow_inc()
 192          * returns is unbalanced, because all other static_key_slow_inc()
 193          * instances block while the update is in progress.
 194          */
 195         if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) {
 196                 WARN(atomic_read(&key->enabled) < 0,
 197                      "jump label: negative count!\n");
 198                 return;
 199         }
 200
 201         if (rate_limit) {
 202                 atomic_inc(&key->enabled);
 203                 schedule_delayed_work(work, rate_limit);
 204         } else {
 205                 jump_label_update(key);
 206         }
 207         jump_label_unlock();
 208 }
 209
 210 static void __static_key_slow_dec(struct static_key *key,
 211                                   unsigned long rate_limit,
 212                                   struct delayed_work *work)
 213 {
 214         cpus_read_lock();
 215         __static_key_slow_dec_cpuslocked(key, rate_limit, work);
 216         cpus_read_unlock();
 217 }
 218
 219 static void jump_label_update_timeout(struct work_struct *work)
 220 {
 221         struct static_key_deferred *key =
 222                 container_of(work, struct static_key_deferred, work.work);
 223         __static_key_slow_dec(&key->key, 0, NULL);
 224 }
 225
 226 void static_key_slow_dec(struct static_key *key)
 227 {
 228         STATIC_KEY_CHECK_USE(key);
 229         __static_key_slow_dec(key, 0, NULL);
 230 }
 231 EXPORT_SYMBOL_GPL(static_key_slow_dec);
 232
 233 void static_key_slow_dec_cpuslocked(struct static_key *key)
 234 {
 235         STATIC_KEY_CHECK_USE(key);
 236         __static_key_slow_dec_cpuslocked(key, 0, NULL);
 237 }
 238
 239 void static_key_slow_dec_deferred(struct static_key_deferred *key)
 240 {
 241         STATIC_KEY_CHECK_USE(key);
 242         __static_key_slow_dec(&key->key, key->timeout, &key->work);
 243 }
 244 EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);
 245
 246 void static_key_deferred_flush(struct static_key_deferred *key)
 247 {
 248         STATIC_KEY_CHECK_USE(key);
 249         flush_delayed_work(&key->work);
 250 }
 251 EXPORT_SYMBOL_GPL(static_key_deferred_flush);
 252
 253 void jump_label_rate_limit(struct static_key_deferred *key,
 254                 unsigned long rl)
 255 {
 256         STATIC_KEY_CHECK_USE(key);
 257         key->timeout = rl;
 258         INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
 259 }
 260 EXPORT_SYMBOL_GPL(jump_label_rate_limit);
 261
 262 static int addr_conflict(struct jump_entry *entry, void *start, void *end)
 263 {
 264         if (entry->code <= (unsigned long)end &&
 265                 entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
 266                 return 1;
 267
 268         return 0;
 269 }
 270
 271 static int __jump_label_text_reserved(struct jump_entry *iter_start,
 272                 struct jump_entry *iter_stop, void *start, void *end)
 273 {
 274         struct jump_entry *iter;
 275
 276         iter = iter_start;
 277         while (iter < iter_stop) {
 278                 if (addr_conflict(iter, start, end))
 279                         return 1;
 280                 iter++;
 281         }
 282
 283         return 0;
 284 }
 285
 286 /*
 287  * Update code which is definitely not currently executing.
 288  * Architectures which need heavyweight synchronization to modify
 289  * running code can override this to make the non-live update case
 290  * cheaper.
 291  */
 292 void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
 293                                             enum jump_label_type type)
 294 {
 295         arch_jump_label_transform(entry, type);
 296 }
 297
 298 static inline struct jump_entry *static_key_entries(struct static_key *key)
 299 {
 300         WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED);
 301         return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK);
 302 }
 303
 304 static inline bool static_key_type(struct static_key *key)
 305 {
 306         return key->type & JUMP_TYPE_TRUE;
 307 }
 308
 309 static inline bool static_key_linked(struct static_key *key)
 310 {
 311         return key->type & JUMP_TYPE_LINKED;
 312 }
 313
 314 static inline void static_key_clear_linked(struct static_key *key)
 315 {
 316         key->type &= ~JUMP_TYPE_LINKED;
 317 }
 318
 319 static inline void static_key_set_linked(struct static_key *key)
 320 {
 321         key->type |= JUMP_TYPE_LINKED;
 322 }
 323
 324 static inline struct static_key *jump_entry_key(struct jump_entry *entry)
 325 {
 326         return (struct static_key *)((unsigned long)entry->key & ~1UL);
 327 }
 328
 329 static bool jump_entry_branch(struct jump_entry *entry)
 330 {
 331         return (unsigned long)entry->key & 1UL;
 332 }
 333
 334 /***
 335  * A 'struct static_key' uses a union such that it either points directly
 336  * to a table of 'struct jump_entry' or to a linked list of modules which in
 337  * turn point to 'struct jump_entry' tables.
 338  *
 339  * The two lower bits of the pointer are used to keep track of which pointer
 340  * type is in use and to store the initial branch direction, we use an access
 341  * function which preserves these bits.
 342  */
 343 static void static_key_set_entries(struct static_key *key,
 344                                    struct jump_entry *entries)
 345 {
 346         unsigned long type;
 347
 348         WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK);
 349         type = key->type & JUMP_TYPE_MASK;
 350         key->entries = entries;
 351         key->type |= type;
 352 }
 353
 354 static enum jump_label_type jump_label_type(struct jump_entry *entry)
 355 {
 356         struct static_key *key = jump_entry_key(entry);
 357         bool enabled = static_key_enabled(key);
 358         bool branch = jump_entry_branch(entry);
 359
 360         /* See the comment in linux/jump_label.h */
 361         return enabled ^ branch;
 362 }
 363
 364 static void __jump_label_update(struct static_key *key,
 365                                 struct jump_entry *entry,
 366                                 struct jump_entry *stop)
 367 {
 368         for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
 369                 /*
 370                  * An entry->code of 0 indicates an entry which has been
 371                  * disabled because it was in an init text area.
 372                  */
 373                 if (entry->code) {
 374                         if (kernel_text_address(entry->code))
 375                                 arch_jump_label_transform(entry, jump_label_type(entry));
 376                         else
 377                                 WARN_ONCE(1, "can't patch jump_label at %pS",
 378                                           (void *)(unsigned long)entry->code);
 379                 }
 380         }
 381 }
 382
 383 void __init jump_label_init(void)
 384 {
 385         struct jump_entry *iter_start = __start___jump_table;
 386         struct jump_entry *iter_stop = __stop___jump_table;
 387         struct static_key *key = NULL;
 388         struct jump_entry *iter;
 389
 390         /*
 391          * Since we are initializing the static_key.enabled field with
 392          * with the 'raw' int values (to avoid pulling in atomic.h) in
 393          * jump_label.h, let's make sure that is safe. There are only two
 394          * cases to check since we initialize to 0 or 1.
 395          */
 396         BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0);
 397         BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1);
 398
 399         if (static_key_initialized)
 400                 return;
 401
 402         cpus_read_lock();
 403         jump_label_lock();
 404         jump_label_sort_entries(iter_start, iter_stop);
 405
 406         for (iter = iter_start; iter < iter_stop; iter++) {
 407                 struct static_key *iterk;
 408
 409                 /* rewrite NOPs */
 410                 if (jump_label_type(iter) == JUMP_LABEL_NOP)
 411                         arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
 412
 413                 iterk = jump_entry_key(iter);
 414                 if (iterk == key)
 415                         continue;
 416
 417                 key = iterk;
 418                 static_key_set_entries(key, iter);
 419         }
 420         static_key_initialized = true;
 421         jump_label_unlock();
 422         cpus_read_unlock();
 423 }
 424
 425 /* Disable any jump label entries in __init/__exit code */
 426 void __init jump_label_invalidate_initmem(void)
 427 {
 428         struct jump_entry *iter_start = __start___jump_table;
 429         struct jump_entry *iter_stop = __stop___jump_table;
 430         struct jump_entry *iter;
 431
 432         for (iter = iter_start; iter < iter_stop; iter++) {
 433                 if (init_section_contains((void *)(unsigned long)iter->code, 1))
 434                         iter->code = 0;
 435         }
 436 }
 437
 438 #ifdef CONFIG_MODULES
 439
 440 static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
 441 {
 442         struct static_key *key = jump_entry_key(entry);
 443         bool type = static_key_type(key);
 444         bool branch = jump_entry_branch(entry);
 445
 446         /* See the comment in linux/jump_label.h */
 447         return type ^ branch;
 448 }
 449
 450 struct static_key_mod {
 451         struct static_key_mod *next;
 452         struct jump_entry *entries;
 453         struct module *mod;
 454 };
 455
 456 static inline struct static_key_mod *static_key_mod(struct static_key *key)
 457 {
 458         WARN_ON_ONCE(!(key->type & JUMP_TYPE_LINKED));
 459         return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK);
 460 }
 461
 462 /***
 463  * key->type and key->next are the same via union.
 464  * This sets key->next and preserves the type bits.
 465  *
 466  * See additional comments above static_key_set_entries().
 467  */
 468 static void static_key_set_mod(struct static_key *key,
 469                                struct static_key_mod *mod)
 470 {
 471         unsigned long type;
 472
 473         WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK);
 474         type = key->type & JUMP_TYPE_MASK;
 475         key->next = mod;
 476         key->type |= type;
 477 }
 478
 479 static int __jump_label_mod_text_reserved(void *start, void *end)
 480 {
 481         struct module *mod;
 482
 483         preempt_disable();
 484         mod = __module_text_address((unsigned long)start);
 485         WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
 486         preempt_enable();
 487
 488         if (!mod)
 489                 return 0;
 490
 491
 492         return __jump_label_text_reserved(mod->jump_entries,
 493                                 mod->jump_entries + mod->num_jump_entries,
 494                                 start, end);
 495 }
 496
 497 static void __jump_label_mod_update(struct static_key *key)
 498 {
 499         struct static_key_mod *mod;
 500
 501         for (mod = static_key_mod(key); mod; mod = mod->next) {
 502                 struct jump_entry *stop;
 503                 struct module *m;
 504
 505                 /*
 506                  * NULL if the static_key is defined in a module
 507                  * that does not use it
 508                  */
 509                 if (!mod->entries)
 510                         continue;
 511
 512                 m = mod->mod;
 513                 if (!m)
 514                         stop = __stop___jump_table;
 515                 else
 516                         stop = m->jump_entries + m->num_jump_entries;
 517                 __jump_label_update(key, mod->entries, stop);
 518         }
 519 }
 520
 521 /***
 522  * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
 523  * @mod: module to patch
 524  *
 525  * Allow for run-time selection of the optimal nops. Before the module
 526  * loads patch these with arch_get_jump_label_nop(), which is specified by
 527  * the arch specific jump label code.
 528  */
 529 void jump_label_apply_nops(struct module *mod)
 530 {
 531         struct jump_entry *iter_start = mod->jump_entries;
 532         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
 533         struct jump_entry *iter;
 534
 535         /* if the module doesn't have jump label entries, just return */
 536         if (iter_start == iter_stop)
 537                 return;
 538
 539         for (iter = iter_start; iter < iter_stop; iter++) {
 540                 /* Only write NOPs for arch_branch_static(). */
 541                 if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
 542                         arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
 543         }
 544 }
 545
 546 static int jump_label_add_module(struct module *mod)
 547 {
 548         struct jump_entry *iter_start = mod->jump_entries;
 549         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
 550         struct jump_entry *iter;
 551         struct static_key *key = NULL;
 552         struct static_key_mod *jlm, *jlm2;
 553
 554         /* if the module doesn't have jump label entries, just return */
 555         if (iter_start == iter_stop)
 556                 return 0;
 557
 558         jump_label_sort_entries(iter_start, iter_stop);
 559
 560         for (iter = iter_start; iter < iter_stop; iter++) {
 561                 struct static_key *iterk;
 562
 563                 iterk = jump_entry_key(iter);
 564                 if (iterk == key)
 565                         continue;
 566
 567                 key = iterk;
 568                 if (within_module(iter->key, mod)) {
 569                         static_key_set_entries(key, iter);
 570                         continue;
 571                 }
 572                 jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
 573                 if (!jlm)
 574                         return -ENOMEM;
 575                 if (!static_key_linked(key)) {
 576                         jlm2 = kzalloc(sizeof(struct static_key_mod),
 577                                        GFP_KERNEL);
 578                         if (!jlm2) {
 579                                 kfree(jlm);
 580                                 return -ENOMEM;
 581                         }
 582                         preempt_disable();
 583                         jlm2->mod = __module_address((unsigned long)key);
 584                         preempt_enable();
 585                         jlm2->entries = static_key_entries(key);
 586                         jlm2->next = NULL;
 587                         static_key_set_mod(key, jlm2);
 588                         static_key_set_linked(key);
 589                 }
 590                 jlm->mod = mod;
 591                 jlm->entries = iter;
 592                 jlm->next = static_key_mod(key);
 593                 static_key_set_mod(key, jlm);
 594                 static_key_set_linked(key);
 595
 596                 /* Only update if we've changed from our initial state */
 597                 if (jump_label_type(iter) != jump_label_init_type(iter))
 598                         __jump_label_update(key, iter, iter_stop);
 599         }
 600
 601         return 0;
 602 }
 603
 604 static void jump_label_del_module(struct module *mod)
 605 {
 606         struct jump_entry *iter_start = mod->jump_entries;
 607         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
 608         struct jump_entry *iter;
 609         struct static_key *key = NULL;
 610         struct static_key_mod *jlm, **prev;
 611
 612         for (iter = iter_start; iter < iter_stop; iter++) {
 613                 if (jump_entry_key(iter) == key)
 614                         continue;
 615
 616                 key = jump_entry_key(iter);
 617
 618                 if (within_module(iter->key, mod))
 619                         continue;
 620
 621                 /* No memory during module load */
 622                 if (WARN_ON(!static_key_linked(key)))
 623                         continue;
 624
 625                 prev = &key->next;
 626                 jlm = static_key_mod(key);
 627
 628                 while (jlm && jlm->mod != mod) {
 629                         prev = &jlm->next;
 630                         jlm = jlm->next;
 631                 }
 632
 633                 /* No memory during module load */
 634                 if (WARN_ON(!jlm))
 635                         continue;
 636
 637                 if (prev == &key->next)
 638                         static_key_set_mod(key, jlm->next);
 639                 else
 640                         *prev = jlm->next;
 641
 642                 kfree(jlm);
 643
 644                 jlm = static_key_mod(key);
 645                 /* if only one etry is left, fold it back into the static_key */
 646                 if (jlm->next == NULL) {
 647                         static_key_set_entries(key, jlm->entries);
 648                         static_key_clear_linked(key);
 649                         kfree(jlm);
 650                 }
 651         }
 652 }
 653
 654 /* Disable any jump label entries in module init code */
 655 static void jump_label_invalidate_module_init(struct module *mod)
 656 {
 657         struct jump_entry *iter_start = mod->jump_entries;
 658         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
 659         struct jump_entry *iter;
 660
 661         for (iter = iter_start; iter < iter_stop; iter++) {
 662                 if (within_module_init(iter->code, mod))
 663                         iter->code = 0;
 664         }
 665 }
 666
 667 static int
 668 jump_label_module_notify(struct notifier_block *self, unsigned long val,
 669                          void *data)
 670 {
 671         struct module *mod = data;
 672         int ret = 0;
 673
 674         cpus_read_lock();
 675         jump_label_lock();
 676
 677         switch (val) {
 678         case MODULE_STATE_COMING:
 679                 ret = jump_label_add_module(mod);
 680                 if (ret) {
 681                         WARN(1, "Failed to allocatote memory: jump_label may not work properly.\n");
 682                         jump_label_del_module(mod);
 683                 }
 684                 break;
 685         case MODULE_STATE_GOING:
 686                 jump_label_del_module(mod);
 687                 break;
 688         case MODULE_STATE_LIVE:
 689                 jump_label_invalidate_module_init(mod);
 690                 break;
 691         }
 692
 693         jump_label_unlock();
 694         cpus_read_unlock();
 695
 696         return notifier_from_errno(ret);
 697 }
 698
 699 static struct notifier_block jump_label_module_nb = {
 700         .notifier_call = jump_label_module_notify,
 701         .priority = 1, /* higher than tracepoints */
 702 };
 703
 704 static __init int jump_label_init_module(void)
 705 {
 706         return register_module_notifier(&jump_label_module_nb);
 707 }
 708 early_initcall(jump_label_init_module);
 709
 710 #endif /* CONFIG_MODULES */
 711
 712 /***
 713  * jump_label_text_reserved - check if addr range is reserved
 714  * @start: start text addr
 715  * @end: end text addr
 716  *
 717  * checks if the text addr located between @start and @end
 718  * overlaps with any of the jump label patch addresses. Code
 719  * that wants to modify kernel text should first verify that
 720  * it does not overlap with any of the jump label addresses.
 721  * Caller must hold jump_label_mutex.
 722  *
 723  * returns 1 if there is an overlap, 0 otherwise
 724  */
 725 int jump_label_text_reserved(void *start, void *end)
 726 {
 727         int ret = __jump_label_text_reserved(__start___jump_table,
 728                         __stop___jump_table, start, end);
 729
 730         if (ret)
 731                 return ret;
 732
 733 #ifdef CONFIG_MODULES
 734         ret = __jump_label_mod_text_reserved(start, end);
 735 #endif
 736         return ret;
 737 }
 738
 739 static void jump_label_update(struct static_key *key)
 740 {
 741         struct jump_entry *stop = __stop___jump_table;
 742         struct jump_entry *entry;
 743 #ifdef CONFIG_MODULES
 744         struct module *mod;
 745
 746         if (static_key_linked(key)) {
 747                 __jump_label_mod_update(key);
 748                 return;
 749         }
 750
 751         preempt_disable();
 752         mod = __module_address((unsigned long)key);
 753         if (mod)
 754                 stop = mod->jump_entries + mod->num_jump_entries;
 755         preempt_enable();
 756 #endif
 757         entry = static_key_entries(key);
 758         /* if there are no users, entry can be NULL */
 759         if (entry)
 760                 __jump_label_update(key, entry, stop);
 761 }
 762
 763 #ifdef CONFIG_STATIC_KEYS_SELFTEST
 764 static DEFINE_STATIC_KEY_TRUE(sk_true);
 765 static DEFINE_STATIC_KEY_FALSE(sk_false);
 766
 767 static __init int jump_label_test(void)
 768 {
 769         int i;
 770
 771         for (i = 0; i < 2; i++) {
 772                 WARN_ON(static_key_enabled(&sk_true.key) != true);
 773                 WARN_ON(static_key_enabled(&sk_false.key) != false);
 774
 775                 WARN_ON(!static_branch_likely(&sk_true));
 776                 WARN_ON(!static_branch_unlikely(&sk_true));
 777                 WARN_ON(static_branch_likely(&sk_false));
 778                 WARN_ON(static_branch_unlikely(&sk_false));
 779
 780                 static_branch_disable(&sk_true);
 781                 static_branch_enable(&sk_false);
 782
 783                 WARN_ON(static_key_enabled(&sk_true.key) == true);
 784                 WARN_ON(static_key_enabled(&sk_false.key) == false);
 785
 786                 WARN_ON(static_branch_likely(&sk_true));
 787                 WARN_ON(static_branch_unlikely(&sk_true));
 788                 WARN_ON(!static_branch_likely(&sk_false));
 789                 WARN_ON(!static_branch_unlikely(&sk_false));
 790
 791                 static_branch_enable(&sk_true);
 792                 static_branch_disable(&sk_false);
 793         }
 794
 795         return 0;
 796 }
 797 early_initcall(jump_label_test);
 798 #endif /* STATIC_KEYS_SELFTEST */
 799
 800 #endif /* HAVE_JUMP_LABEL */