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