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