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 bool static_key_slow_try_dec(struct static_key *key)
 206 {
 207         int val;
 208
 209         val = atomic_fetch_add_unless(&key->enabled, -1, 1);
 210         if (val == 1)
 211                 return false;
 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         WARN(val < 0, "jump label: negative count!\n");
 221         return true;
 222 }
 223
 224 static void __static_key_slow_dec_cpuslocked(struct static_key *key)
 225 {
 226         lockdep_assert_cpus_held();
 227
 228         if (static_key_slow_try_dec(key))
 229                 return;
 230
 231         jump_label_lock();
 232         if (atomic_dec_and_test(&key->enabled))
 233                 jump_label_update(key);
 234         jump_label_unlock();
 235 }
 236
 237 static void __static_key_slow_dec(struct static_key *key)
 238 {
 239         cpus_read_lock();
 240         __static_key_slow_dec_cpuslocked(key);
 241         cpus_read_unlock();
 242 }
 243
 244 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);
 249 }
 250 EXPORT_SYMBOL_GPL(jump_label_update_timeout);
 251
 252 void static_key_slow_dec(struct static_key *key)
 253 {
 254         STATIC_KEY_CHECK_USE(key);
 255         __static_key_slow_dec(key);
 256 }
 257 EXPORT_SYMBOL_GPL(static_key_slow_dec);
 258
 259 void static_key_slow_dec_cpuslocked(struct static_key *key)
 260 {
 261         STATIC_KEY_CHECK_USE(key);
 262         __static_key_slow_dec_cpuslocked(key);
 263 }
 264
 265 void __static_key_slow_dec_deferred(struct static_key *key,
 266                                     struct delayed_work *work,
 267                                     unsigned long timeout)
 268 {
 269         STATIC_KEY_CHECK_USE(key);
 270
 271         if (static_key_slow_try_dec(key))
 272                 return;
 273
 274         schedule_delayed_work(work, timeout);
 275 }
 276 EXPORT_SYMBOL_GPL(__static_key_slow_dec_deferred);
 277
 278 void __static_key_deferred_flush(void *key, struct delayed_work *work)
 279 {
 280         STATIC_KEY_CHECK_USE(key);
 281         flush_delayed_work(work);
 282 }
 283 EXPORT_SYMBOL_GPL(__static_key_deferred_flush);
 284
 285 void jump_label_rate_limit(struct static_key_deferred *key,
 286                 unsigned long rl)
 287 {
 288         STATIC_KEY_CHECK_USE(key);
 289         key->timeout = rl;
 290         INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
 291 }
 292 EXPORT_SYMBOL_GPL(jump_label_rate_limit);
 293
 294 static int addr_conflict(struct jump_entry *entry, void *start, void *end)
 295 {
 296         if (jump_entry_code(entry) <= (unsigned long)end &&
 297             jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
 298                 return 1;
 299
 300         return 0;
 301 }
 302
 303 static int __jump_label_text_reserved(struct jump_entry *iter_start,
 304                 struct jump_entry *iter_stop, void *start, void *end)
 305 {
 306         struct jump_entry *iter;
 307
 308         iter = iter_start;
 309         while (iter < iter_stop) {
 310                 if (addr_conflict(iter, start, end))
 311                         return 1;
 312                 iter++;
 313         }
 314
 315         return 0;
 316 }
 317
 318 /*
 319  * Update code which is definitely not currently executing.
 320  * Architectures which need heavyweight synchronization to modify
 321  * running code can override this to make the non-live update case
 322  * cheaper.
 323  */
 324 void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
 325                                             enum jump_label_type type)
 326 {
 327         arch_jump_label_transform(entry, type);
 328 }
 329
 330 static inline struct jump_entry *static_key_entries(struct static_key *key)
 331 {
 332         WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED);
 333         return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK);
 334 }
 335
 336 static inline bool static_key_type(struct static_key *key)
 337 {
 338         return key->type & JUMP_TYPE_TRUE;
 339 }
 340
 341 static inline bool static_key_linked(struct static_key *key)
 342 {
 343         return key->type & JUMP_TYPE_LINKED;
 344 }
 345
 346 static inline void static_key_clear_linked(struct static_key *key)
 347 {
 348         key->type &= ~JUMP_TYPE_LINKED;
 349 }
 350
 351 static inline void static_key_set_linked(struct static_key *key)
 352 {
 353         key->type |= JUMP_TYPE_LINKED;
 354 }
 355
 356 /***
 357  * A 'struct static_key' uses a union such that it either points directly
 358  * to a table of 'struct jump_entry' or to a linked list of modules which in
 359  * turn point to 'struct jump_entry' tables.
 360  *
 361  * The two lower bits of the pointer are used to keep track of which pointer
 362  * type is in use and to store the initial branch direction, we use an access
 363  * function which preserves these bits.
 364  */
 365 static void static_key_set_entries(struct static_key *key,
 366                                    struct jump_entry *entries)
 367 {
 368         unsigned long type;
 369
 370         WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK);
 371         type = key->type & JUMP_TYPE_MASK;
 372         key->entries = entries;
 373         key->type |= type;
 374 }
 375
 376 static enum jump_label_type jump_label_type(struct jump_entry *entry)
 377 {
 378         struct static_key *key = jump_entry_key(entry);
 379         bool enabled = static_key_enabled(key);
 380         bool branch = jump_entry_is_branch(entry);
 381
 382         /* See the comment in linux/jump_label.h */
 383         return enabled ^ branch;
 384 }
 385
 386 static void __jump_label_update(struct static_key *key,
 387                                 struct jump_entry *entry,
 388                                 struct jump_entry *stop,
 389                                 bool init)
 390 {
 391         for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
 392                 /*
 393                  * An entry->code of 0 indicates an entry which has been
 394                  * disabled because it was in an init text area.
 395                  */
 396                 if (init || !jump_entry_is_init(entry)) {
 397                         if (kernel_text_address(jump_entry_code(entry)))
 398                                 arch_jump_label_transform(entry, jump_label_type(entry));
 399                         else
 400                                 WARN_ONCE(1, "can't patch jump_label at %pS",
 401                                           (void *)jump_entry_code(entry));
 402                 }
 403         }
 404 }
 405
 406 void __init jump_label_init(void)
 407 {
 408         struct jump_entry *iter_start = __start___jump_table;
 409         struct jump_entry *iter_stop = __stop___jump_table;
 410         struct static_key *key = NULL;
 411         struct jump_entry *iter;
 412
 413         /*
 414          * Since we are initializing the static_key.enabled field with
 415          * with the 'raw' int values (to avoid pulling in atomic.h) in
 416          * jump_label.h, let's make sure that is safe. There are only two
 417          * cases to check since we initialize to 0 or 1.
 418          */
 419         BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0);
 420         BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1);
 421
 422         if (static_key_initialized)
 423                 return;
 424
 425         cpus_read_lock();
 426         jump_label_lock();
 427         jump_label_sort_entries(iter_start, iter_stop);
 428
 429         for (iter = iter_start; iter < iter_stop; iter++) {
 430                 struct static_key *iterk;
 431
 432                 /* rewrite NOPs */
 433                 if (jump_label_type(iter) == JUMP_LABEL_NOP)
 434                         arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
 435
 436                 if (init_section_contains((void *)jump_entry_code(iter), 1))
 437                         jump_entry_set_init(iter);
 438
 439                 iterk = jump_entry_key(iter);
 440                 if (iterk == key)
 441                         continue;
 442
 443                 key = iterk;
 444                 static_key_set_entries(key, iter);
 445         }
 446         static_key_initialized = true;
 447         jump_label_unlock();
 448         cpus_read_unlock();
 449 }
 450
 451 #ifdef CONFIG_MODULES
 452
 453 static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
 454 {
 455         struct static_key *key = jump_entry_key(entry);
 456         bool type = static_key_type(key);
 457         bool branch = jump_entry_is_branch(entry);
 458
 459         /* See the comment in linux/jump_label.h */
 460         return type ^ branch;
 461 }
 462
 463 struct static_key_mod {
 464         struct static_key_mod *next;
 465         struct jump_entry *entries;
 466         struct module *mod;
 467 };
 468
 469 static inline struct static_key_mod *static_key_mod(struct static_key *key)
 470 {
 471         WARN_ON_ONCE(!static_key_linked(key));
 472         return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK);
 473 }
 474
 475 /***
 476  * key->type and key->next are the same via union.
 477  * This sets key->next and preserves the type bits.
 478  *
 479  * See additional comments above static_key_set_entries().
 480  */
 481 static void static_key_set_mod(struct static_key *key,
 482                                struct static_key_mod *mod)
 483 {
 484         unsigned long type;
 485
 486         WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK);
 487         type = key->type & JUMP_TYPE_MASK;
 488         key->next = mod;
 489         key->type |= type;
 490 }
 491
 492 static int __jump_label_mod_text_reserved(void *start, void *end)
 493 {
 494         struct module *mod;
 495
 496         preempt_disable();
 497         mod = __module_text_address((unsigned long)start);
 498         WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
 499         preempt_enable();
 500
 501         if (!mod)
 502                 return 0;
 503
 504
 505         return __jump_label_text_reserved(mod->jump_entries,
 506                                 mod->jump_entries + mod->num_jump_entries,
 507                                 start, end);
 508 }
 509
 510 static void __jump_label_mod_update(struct static_key *key)
 511 {
 512         struct static_key_mod *mod;
 513
 514         for (mod = static_key_mod(key); mod; mod = mod->next) {
 515                 struct jump_entry *stop;
 516                 struct module *m;
 517
 518                 /*
 519                  * NULL if the static_key is defined in a module
 520                  * that does not use it
 521                  */
 522                 if (!mod->entries)
 523                         continue;
 524
 525                 m = mod->mod;
 526                 if (!m)
 527                         stop = __stop___jump_table;
 528                 else
 529                         stop = m->jump_entries + m->num_jump_entries;
 530                 __jump_label_update(key, mod->entries, stop,
 531                                     m && m->state == MODULE_STATE_COMING);
 532         }
 533 }
 534
 535 /***
 536  * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
 537  * @mod: module to patch
 538  *
 539  * Allow for run-time selection of the optimal nops. Before the module
 540  * loads patch these with arch_get_jump_label_nop(), which is specified by
 541  * the arch specific jump label code.
 542  */
 543 void jump_label_apply_nops(struct module *mod)
 544 {
 545         struct jump_entry *iter_start = mod->jump_entries;
 546         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
 547         struct jump_entry *iter;
 548
 549         /* if the module doesn't have jump label entries, just return */
 550         if (iter_start == iter_stop)
 551                 return;
 552
 553         for (iter = iter_start; iter < iter_stop; iter++) {
 554                 /* Only write NOPs for arch_branch_static(). */
 555                 if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
 556                         arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
 557         }
 558 }
 559
 560 static int jump_label_add_module(struct module *mod)
 561 {
 562         struct jump_entry *iter_start = mod->jump_entries;
 563         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
 564         struct jump_entry *iter;
 565         struct static_key *key = NULL;
 566         struct static_key_mod *jlm, *jlm2;
 567
 568         /* if the module doesn't have jump label entries, just return */
 569         if (iter_start == iter_stop)
 570                 return 0;
 571
 572         jump_label_sort_entries(iter_start, iter_stop);
 573
 574         for (iter = iter_start; iter < iter_stop; iter++) {
 575                 struct static_key *iterk;
 576
 577                 if (within_module_init(jump_entry_code(iter), mod))
 578                         jump_entry_set_init(iter);
 579
 580                 iterk = jump_entry_key(iter);
 581                 if (iterk == key)
 582                         continue;
 583
 584                 key = iterk;
 585                 if (within_module((unsigned long)key, mod)) {
 586                         static_key_set_entries(key, iter);
 587                         continue;
 588                 }
 589                 jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
 590                 if (!jlm)
 591                         return -ENOMEM;
 592                 if (!static_key_linked(key)) {
 593                         jlm2 = kzalloc(sizeof(struct static_key_mod),
 594                                        GFP_KERNEL);
 595                         if (!jlm2) {
 596                                 kfree(jlm);
 597                                 return -ENOMEM;
 598                         }
 599                         preempt_disable();
 600                         jlm2->mod = __module_address((unsigned long)key);
 601                         preempt_enable();
 602                         jlm2->entries = static_key_entries(key);
 603                         jlm2->next = NULL;
 604                         static_key_set_mod(key, jlm2);
 605                         static_key_set_linked(key);
 606                 }
 607                 jlm->mod = mod;
 608                 jlm->entries = iter;
 609                 jlm->next = static_key_mod(key);
 610                 static_key_set_mod(key, jlm);
 611                 static_key_set_linked(key);
 612
 613                 /* Only update if we've changed from our initial state */
 614                 if (jump_label_type(iter) != jump_label_init_type(iter))
 615                         __jump_label_update(key, iter, iter_stop, true);
 616         }
 617
 618         return 0;
 619 }
 620
 621 static void jump_label_del_module(struct module *mod)
 622 {
 623         struct jump_entry *iter_start = mod->jump_entries;
 624         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
 625         struct jump_entry *iter;
 626         struct static_key *key = NULL;
 627         struct static_key_mod *jlm, **prev;
 628
 629         for (iter = iter_start; iter < iter_stop; iter++) {
 630                 if (jump_entry_key(iter) == key)
 631                         continue;
 632
 633                 key = jump_entry_key(iter);
 634
 635                 if (within_module((unsigned long)key, mod))
 636                         continue;
 637
 638                 /* No memory during module load */
 639                 if (WARN_ON(!static_key_linked(key)))
 640                         continue;
 641
 642                 prev = &key->next;
 643                 jlm = static_key_mod(key);
 644
 645                 while (jlm && jlm->mod != mod) {
 646                         prev = &jlm->next;
 647                         jlm = jlm->next;
 648                 }
 649
 650                 /* No memory during module load */
 651                 if (WARN_ON(!jlm))
 652                         continue;
 653
 654                 if (prev == &key->next)
 655                         static_key_set_mod(key, jlm->next);
 656                 else
 657                         *prev = jlm->next;
 658
 659                 kfree(jlm);
 660
 661                 jlm = static_key_mod(key);
 662                 /* if only one etry is left, fold it back into the static_key */
 663                 if (jlm->next == NULL) {
 664                         static_key_set_entries(key, jlm->entries);
 665                         static_key_clear_linked(key);
 666                         kfree(jlm);
 667                 }
 668         }
 669 }
 670
 671 static int
 672 jump_label_module_notify(struct notifier_block *self, unsigned long val,
 673                          void *data)
 674 {
 675         struct module *mod = data;
 676         int ret = 0;
 677
 678         cpus_read_lock();
 679         jump_label_lock();
 680
 681         switch (val) {
 682         case MODULE_STATE_COMING:
 683                 ret = jump_label_add_module(mod);
 684                 if (ret) {
 685                         WARN(1, "Failed to allocate memory: jump_label may not work properly.\n");
 686                         jump_label_del_module(mod);
 687                 }
 688                 break;
 689         case MODULE_STATE_GOING:
 690                 jump_label_del_module(mod);
 691                 break;
 692         }
 693
 694         jump_label_unlock();
 695         cpus_read_unlock();
 696
 697         return notifier_from_errno(ret);
 698 }
 699
 700 static struct notifier_block jump_label_module_nb = {
 701         .notifier_call = jump_label_module_notify,
 702         .priority = 1, /* higher than tracepoints */
 703 };
 704
 705 static __init int jump_label_init_module(void)
 706 {
 707         return register_module_notifier(&jump_label_module_nb);
 708 }
 709 early_initcall(jump_label_init_module);
 710
 711 #endif /* CONFIG_MODULES */
 712
 713 /***
 714  * jump_label_text_reserved - check if addr range is reserved
 715  * @start: start text addr
 716  * @end: end text addr
 717  *
 718  * checks if the text addr located between @start and @end
 719  * overlaps with any of the jump label patch addresses. Code
 720  * that wants to modify kernel text should first verify that
 721  * it does not overlap with any of the jump label addresses.
 722  * Caller must hold jump_label_mutex.
 723  *
 724  * returns 1 if there is an overlap, 0 otherwise
 725  */
 726 int jump_label_text_reserved(void *start, void *end)
 727 {
 728         int ret = __jump_label_text_reserved(__start___jump_table,
 729                         __stop___jump_table, start, end);
 730
 731         if (ret)
 732                 return ret;
 733
 734 #ifdef CONFIG_MODULES
 735         ret = __jump_label_mod_text_reserved(start, end);
 736 #endif
 737         return ret;
 738 }
 739
 740 static void jump_label_update(struct static_key *key)
 741 {
 742         struct jump_entry *stop = __stop___jump_table;
 743         struct jump_entry *entry;
 744 #ifdef CONFIG_MODULES
 745         struct module *mod;
 746
 747         if (static_key_linked(key)) {
 748                 __jump_label_mod_update(key);
 749                 return;
 750         }
 751
 752         preempt_disable();
 753         mod = __module_address((unsigned long)key);
 754         if (mod)
 755                 stop = mod->jump_entries + mod->num_jump_entries;
 756         preempt_enable();
 757 #endif
 758         entry = static_key_entries(key);
 759         /* if there are no users, entry can be NULL */
 760         if (entry)
 761                 __jump_label_update(key, entry, stop,
 762                                     system_state < SYSTEM_RUNNING);
 763 }
 764
 765 #ifdef CONFIG_STATIC_KEYS_SELFTEST
 766 static DEFINE_STATIC_KEY_TRUE(sk_true);
 767 static DEFINE_STATIC_KEY_FALSE(sk_false);
 768
 769 static __init int jump_label_test(void)
 770 {
 771         int i;
 772
 773         for (i = 0; i < 2; i++) {
 774                 WARN_ON(static_key_enabled(&sk_true.key) != true);
 775                 WARN_ON(static_key_enabled(&sk_false.key) != false);
 776
 777                 WARN_ON(!static_branch_likely(&sk_true));
 778                 WARN_ON(!static_branch_unlikely(&sk_true));
 779                 WARN_ON(static_branch_likely(&sk_false));
 780                 WARN_ON(static_branch_unlikely(&sk_false));
 781
 782                 static_branch_disable(&sk_true);
 783                 static_branch_enable(&sk_false);
 784
 785                 WARN_ON(static_key_enabled(&sk_true.key) == true);
 786                 WARN_ON(static_key_enabled(&sk_false.key) == false);
 787
 788                 WARN_ON(static_branch_likely(&sk_true));
 789                 WARN_ON(static_branch_unlikely(&sk_true));
 790                 WARN_ON(!static_branch_likely(&sk_false));
 791                 WARN_ON(!static_branch_unlikely(&sk_false));
 792
 793                 static_branch_enable(&sk_true);
 794                 static_branch_disable(&sk_false);
 795         }
 796
 797         return 0;
 798 }
 799 early_initcall(jump_label_test);
 800 #endif /* STATIC_KEYS_SELFTEST */