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                  * An entry->code of 0 indicates an entry which has been
 370                  * disabled because it was in an init text area.
 371                  */
 372                 if (entry->code) {
 373                         if (kernel_text_address(entry->code))
 374                                 arch_jump_label_transform(entry, jump_label_type(entry));
 375                         else
 376                                 WARN_ONCE(1, "can't patch jump_label at %pS",
 377                                           (void *)(unsigned long)entry->code);
 378                 }
 379         }
 380 }
 381
 382 void __init jump_label_init(void)
 383 {
 384         struct jump_entry *iter_start = __start___jump_table;
 385         struct jump_entry *iter_stop = __stop___jump_table;
 386         struct static_key *key = NULL;
 387         struct jump_entry *iter;
 388
 389         /*
 390          * Since we are initializing the static_key.enabled field with
 391          * with the 'raw' int values (to avoid pulling in atomic.h) in
 392          * jump_label.h, let's make sure that is safe. There are only two
 393          * cases to check since we initialize to 0 or 1.
 394          */
 395         BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0);
 396         BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1);
 397
 398         if (static_key_initialized)
 399                 return;
 400
 401         cpus_read_lock();
 402         jump_label_lock();
 403         jump_label_sort_entries(iter_start, iter_stop);
 404
 405         for (iter = iter_start; iter < iter_stop; iter++) {
 406                 struct static_key *iterk;
 407
 408                 /* rewrite NOPs */
 409                 if (jump_label_type(iter) == JUMP_LABEL_NOP)
 410                         arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
 411
 412                 iterk = jump_entry_key(iter);
 413                 if (iterk == key)
 414                         continue;
 415
 416                 key = iterk;
 417                 static_key_set_entries(key, iter);
 418         }
 419         static_key_initialized = true;
 420         jump_label_unlock();
 421         cpus_read_unlock();
 422 }
 423
 424 /* Disable any jump label entries in __init code */
 425 void __init jump_label_invalidate_init(void)
 426 {
 427         struct jump_entry *iter_start = __start___jump_table;
 428         struct jump_entry *iter_stop = __stop___jump_table;
 429         struct jump_entry *iter;
 430
 431         for (iter = iter_start; iter < iter_stop; iter++) {
 432                 if (init_kernel_text(iter->code))
 433                         iter->code = 0;
 434         }
 435 }
 436
 437 #ifdef CONFIG_MODULES
 438
 439 static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
 440 {
 441         struct static_key *key = jump_entry_key(entry);
 442         bool type = static_key_type(key);
 443         bool branch = jump_entry_branch(entry);
 444
 445         /* See the comment in linux/jump_label.h */
 446         return type ^ branch;
 447 }
 448
 449 struct static_key_mod {
 450         struct static_key_mod *next;
 451         struct jump_entry *entries;
 452         struct module *mod;
 453 };
 454
 455 static inline struct static_key_mod *static_key_mod(struct static_key *key)
 456 {
 457         WARN_ON_ONCE(!(key->type & JUMP_TYPE_LINKED));
 458         return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK);
 459 }
 460
 461 /***
 462  * key->type and key->next are the same via union.
 463  * This sets key->next and preserves the type bits.
 464  *
 465  * See additional comments above static_key_set_entries().
 466  */
 467 static void static_key_set_mod(struct static_key *key,
 468                                struct static_key_mod *mod)
 469 {
 470         unsigned long type;
 471
 472         WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK);
 473         type = key->type & JUMP_TYPE_MASK;
 474         key->next = mod;
 475         key->type |= type;
 476 }
 477
 478 static int __jump_label_mod_text_reserved(void *start, void *end)
 479 {
 480         struct module *mod;
 481
 482         preempt_disable();
 483         mod = __module_text_address((unsigned long)start);
 484         WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
 485         preempt_enable();
 486
 487         if (!mod)
 488                 return 0;
 489
 490
 491         return __jump_label_text_reserved(mod->jump_entries,
 492                                 mod->jump_entries + mod->num_jump_entries,
 493                                 start, end);
 494 }
 495
 496 static void __jump_label_mod_update(struct static_key *key)
 497 {
 498         struct static_key_mod *mod;
 499
 500         for (mod = static_key_mod(key); mod; mod = mod->next) {
 501                 struct jump_entry *stop;
 502                 struct module *m;
 503
 504                 /*
 505                  * NULL if the static_key is defined in a module
 506                  * that does not use it
 507                  */
 508                 if (!mod->entries)
 509                         continue;
 510
 511                 m = mod->mod;
 512                 if (!m)
 513                         stop = __stop___jump_table;
 514                 else
 515                         stop = m->jump_entries + m->num_jump_entries;
 516                 __jump_label_update(key, mod->entries, stop);
 517         }
 518 }
 519
 520 /***
 521  * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
 522  * @mod: module to patch
 523  *
 524  * Allow for run-time selection of the optimal nops. Before the module
 525  * loads patch these with arch_get_jump_label_nop(), which is specified by
 526  * the arch specific jump label code.
 527  */
 528 void jump_label_apply_nops(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
 534         /* if the module doesn't have jump label entries, just return */
 535         if (iter_start == iter_stop)
 536                 return;
 537
 538         for (iter = iter_start; iter < iter_stop; iter++) {
 539                 /* Only write NOPs for arch_branch_static(). */
 540                 if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
 541                         arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
 542         }
 543 }
 544
 545 static int jump_label_add_module(struct module *mod)
 546 {
 547         struct jump_entry *iter_start = mod->jump_entries;
 548         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
 549         struct jump_entry *iter;
 550         struct static_key *key = NULL;
 551         struct static_key_mod *jlm, *jlm2;
 552
 553         /* if the module doesn't have jump label entries, just return */
 554         if (iter_start == iter_stop)
 555                 return 0;
 556
 557         jump_label_sort_entries(iter_start, iter_stop);
 558
 559         for (iter = iter_start; iter < iter_stop; iter++) {
 560                 struct static_key *iterk;
 561
 562                 iterk = jump_entry_key(iter);
 563                 if (iterk == key)
 564                         continue;
 565
 566                 key = iterk;
 567                 if (within_module(iter->key, mod)) {
 568                         static_key_set_entries(key, iter);
 569                         continue;
 570                 }
 571                 jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
 572                 if (!jlm)
 573                         return -ENOMEM;
 574                 if (!static_key_linked(key)) {
 575                         jlm2 = kzalloc(sizeof(struct static_key_mod),
 576                                        GFP_KERNEL);
 577                         if (!jlm2) {
 578                                 kfree(jlm);
 579                                 return -ENOMEM;
 580                         }
 581                         preempt_disable();
 582                         jlm2->mod = __module_address((unsigned long)key);
 583                         preempt_enable();
 584                         jlm2->entries = static_key_entries(key);
 585                         jlm2->next = NULL;
 586                         static_key_set_mod(key, jlm2);
 587                         static_key_set_linked(key);
 588                 }
 589                 jlm->mod = mod;
 590                 jlm->entries = iter;
 591                 jlm->next = static_key_mod(key);
 592                 static_key_set_mod(key, jlm);
 593                 static_key_set_linked(key);
 594
 595                 /* Only update if we've changed from our initial state */
 596                 if (jump_label_type(iter) != jump_label_init_type(iter))
 597                         __jump_label_update(key, iter, iter_stop);
 598         }
 599
 600         return 0;
 601 }
 602
 603 static void jump_label_del_module(struct module *mod)
 604 {
 605         struct jump_entry *iter_start = mod->jump_entries;
 606         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
 607         struct jump_entry *iter;
 608         struct static_key *key = NULL;
 609         struct static_key_mod *jlm, **prev;
 610
 611         for (iter = iter_start; iter < iter_stop; iter++) {
 612                 if (jump_entry_key(iter) == key)
 613                         continue;
 614
 615                 key = jump_entry_key(iter);
 616
 617                 if (within_module(iter->key, mod))
 618                         continue;
 619
 620                 /* No memory during module load */
 621                 if (WARN_ON(!static_key_linked(key)))
 622                         continue;
 623
 624                 prev = &key->next;
 625                 jlm = static_key_mod(key);
 626
 627                 while (jlm && jlm->mod != mod) {
 628                         prev = &jlm->next;
 629                         jlm = jlm->next;
 630                 }
 631
 632                 /* No memory during module load */
 633                 if (WARN_ON(!jlm))
 634                         continue;
 635
 636                 if (prev == &key->next)
 637                         static_key_set_mod(key, jlm->next);
 638                 else
 639                         *prev = jlm->next;
 640
 641                 kfree(jlm);
 642
 643                 jlm = static_key_mod(key);
 644                 /* if only one etry is left, fold it back into the static_key */
 645                 if (jlm->next == NULL) {
 646                         static_key_set_entries(key, jlm->entries);
 647                         static_key_clear_linked(key);
 648                         kfree(jlm);
 649                 }
 650         }
 651 }
 652
 653 /* Disable any jump label entries in module init code */
 654 static void jump_label_invalidate_module_init(struct module *mod)
 655 {
 656         struct jump_entry *iter_start = mod->jump_entries;
 657         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
 658         struct jump_entry *iter;
 659
 660         for (iter = iter_start; iter < iter_stop; iter++) {
 661                 if (within_module_init(iter->code, mod))
 662                         iter->code = 0;
 663         }
 664 }
 665
 666 static int
 667 jump_label_module_notify(struct notifier_block *self, unsigned long val,
 668                          void *data)
 669 {
 670         struct module *mod = data;
 671         int ret = 0;
 672
 673         cpus_read_lock();
 674         jump_label_lock();
 675
 676         switch (val) {
 677         case MODULE_STATE_COMING:
 678                 ret = jump_label_add_module(mod);
 679                 if (ret) {
 680                         WARN(1, "Failed to allocatote memory: jump_label may not work properly.\n");
 681                         jump_label_del_module(mod);
 682                 }
 683                 break;
 684         case MODULE_STATE_GOING:
 685                 jump_label_del_module(mod);
 686                 break;
 687         case MODULE_STATE_LIVE:
 688                 jump_label_invalidate_module_init(mod);
 689                 break;
 690         }
 691
 692         jump_label_unlock();
 693         cpus_read_unlock();
 694
 695         return notifier_from_errno(ret);
 696 }
 697
 698 static struct notifier_block jump_label_module_nb = {
 699         .notifier_call = jump_label_module_notify,
 700         .priority = 1, /* higher than tracepoints */
 701 };
 702
 703 static __init int jump_label_init_module(void)
 704 {
 705         return register_module_notifier(&jump_label_module_nb);
 706 }
 707 early_initcall(jump_label_init_module);
 708
 709 #endif /* CONFIG_MODULES */
 710
 711 /***
 712  * jump_label_text_reserved - check if addr range is reserved
 713  * @start: start text addr
 714  * @end: end text addr
 715  *
 716  * checks if the text addr located between @start and @end
 717  * overlaps with any of the jump label patch addresses. Code
 718  * that wants to modify kernel text should first verify that
 719  * it does not overlap with any of the jump label addresses.
 720  * Caller must hold jump_label_mutex.
 721  *
 722  * returns 1 if there is an overlap, 0 otherwise
 723  */
 724 int jump_label_text_reserved(void *start, void *end)
 725 {
 726         int ret = __jump_label_text_reserved(__start___jump_table,
 727                         __stop___jump_table, start, end);
 728
 729         if (ret)
 730                 return ret;
 731
 732 #ifdef CONFIG_MODULES
 733         ret = __jump_label_mod_text_reserved(start, end);
 734 #endif
 735         return ret;
 736 }
 737
 738 static void jump_label_update(struct static_key *key)
 739 {
 740         struct jump_entry *stop = __stop___jump_table;
 741         struct jump_entry *entry;
 742 #ifdef CONFIG_MODULES
 743         struct module *mod;
 744
 745         if (static_key_linked(key)) {
 746                 __jump_label_mod_update(key);
 747                 return;
 748         }
 749
 750         preempt_disable();
 751         mod = __module_address((unsigned long)key);
 752         if (mod)
 753                 stop = mod->jump_entries + mod->num_jump_entries;
 754         preempt_enable();
 755 #endif
 756         entry = static_key_entries(key);
 757         /* if there are no users, entry can be NULL */
 758         if (entry)
 759                 __jump_label_update(key, entry, stop);
 760 }
 761
 762 #ifdef CONFIG_STATIC_KEYS_SELFTEST
 763 static DEFINE_STATIC_KEY_TRUE(sk_true);
 764 static DEFINE_STATIC_KEY_FALSE(sk_false);
 765
 766 static __init int jump_label_test(void)
 767 {
 768         int i;
 769
 770         for (i = 0; i < 2; i++) {
 771                 WARN_ON(static_key_enabled(&sk_true.key) != true);
 772                 WARN_ON(static_key_enabled(&sk_false.key) != false);
 773
 774                 WARN_ON(!static_branch_likely(&sk_true));
 775                 WARN_ON(!static_branch_unlikely(&sk_true));
 776                 WARN_ON(static_branch_likely(&sk_false));
 777                 WARN_ON(static_branch_unlikely(&sk_false));
 778
 779                 static_branch_disable(&sk_true);
 780                 static_branch_enable(&sk_false);
 781
 782                 WARN_ON(static_key_enabled(&sk_true.key) == true);
 783                 WARN_ON(static_key_enabled(&sk_false.key) == false);
 784
 785                 WARN_ON(static_branch_likely(&sk_true));
 786                 WARN_ON(static_branch_unlikely(&sk_true));
 787                 WARN_ON(!static_branch_likely(&sk_false));
 788                 WARN_ON(!static_branch_unlikely(&sk_false));
 789
 790                 static_branch_enable(&sk_true);
 791                 static_branch_disable(&sk_false);
 792         }
 793
 794         return 0;
 795 }
 796 early_initcall(jump_label_test);
 797 #endif /* STATIC_KEYS_SELFTEST */
 798
 799 #endif /* HAVE_JUMP_LABEL */