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