1// SPDX-License-Identifier: GPL-2.0-only 2/* 3 * jump label support 4 * 5 * Copyright (C) 2009 Jason Baron <jbaron@redhat.com> 6 * Copyright (C) 2011 Peter Zijlstra 7 * 8 */ 9#include <linux/memory.h> 10#include <linux/uaccess.h> 11#include <linux/module.h> 12#include <linux/list.h> 13#include <linux/slab.h> 14#include <linux/sort.h> 15#include <linux/err.h> 16#include <linux/static_key.h> 17#include <linux/jump_label_ratelimit.h> 18#include <linux/bug.h> 19#include <linux/cpu.h> 20#include <asm/sections.h> 21 22/* mutex to protect coming/going of the jump_label table */ 23static DEFINE_MUTEX(jump_label_mutex); 24 25void jump_label_lock(void) 26{ 27 mutex_lock(&jump_label_mutex); 28} 29 30void jump_label_unlock(void) 31{ 32 mutex_unlock(&jump_label_mutex); 33} 34 35static 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 /* 41 * Entrires are sorted by key. 42 */ 43 if (jump_entry_key(jea) < jump_entry_key(jeb)) 44 return -1; 45 46 if (jump_entry_key(jea) > jump_entry_key(jeb)) 47 return 1; 48 49 /* 50 * In the batching mode, entries should also be sorted by the code 51 * inside the already sorted list of entries, enabling a bsearch in 52 * the vector. 53 */ 54 if (jump_entry_code(jea) < jump_entry_code(jeb)) 55 return -1; 56 57 if (jump_entry_code(jea) > jump_entry_code(jeb)) 58 return 1; 59 60 return 0; 61} 62 63static void jump_label_swap(void *a, void *b, int size) 64{ 65 long delta = (unsigned long)a - (unsigned long)b; 66 struct jump_entry *jea = a; 67 struct jump_entry *jeb = b; 68 struct jump_entry tmp = *jea; 69 70 jea->code = jeb->code - delta; 71 jea->target = jeb->target - delta; 72 jea->key = jeb->key - delta; 73 74 jeb->code = tmp.code + delta; 75 jeb->target = tmp.target + delta; 76 jeb->key = tmp.key + delta; 77} 78 79static void 80jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop) 81{ 82 unsigned long size; 83 void *swapfn = NULL; 84 85 if (IS_ENABLED(CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE)) 86 swapfn = jump_label_swap; 87 88 size = (((unsigned long)stop - (unsigned long)start) 89 / sizeof(struct jump_entry)); 90 sort(start, size, sizeof(struct jump_entry), jump_label_cmp, swapfn); 91} 92 93static void jump_label_update(struct static_key *key); 94 95/* 96 * There are similar definitions for the !CONFIG_JUMP_LABEL case in jump_label.h. 97 * The use of 'atomic_read()' requires atomic.h and its problematic for some 98 * kernel headers such as kernel.h and others. Since static_key_count() is not 99 * used in the branch statements as it is for the !CONFIG_JUMP_LABEL case its ok 100 * to have it be a function here. Similarly, for 'static_key_enable()' and 101 * 'static_key_disable()', which require bug.h. This should allow jump_label.h 102 * to be included from most/all places for CONFIG_JUMP_LABEL. 103 */ 104int static_key_count(struct static_key *key) 105{ 106 /* 107 * -1 means the first static_key_slow_inc() is in progress. 108 * static_key_enabled() must return true, so return 1 here. 109 */ 110 int n = atomic_read(&key->enabled); 111 112 return n >= 0 ? n : 1; 113} 114EXPORT_SYMBOL_GPL(static_key_count); 115 116/* 117 * static_key_fast_inc_not_disabled - adds a user for a static key 118 * @key: static key that must be already enabled 119 * 120 * The caller must make sure that the static key can't get disabled while 121 * in this function. It doesn't patch jump labels, only adds a user to 122 * an already enabled static key. 123 * 124 * Returns true if the increment was done. Unlike refcount_t the ref counter 125 * is not saturated, but will fail to increment on overflow. 126 */ 127bool static_key_fast_inc_not_disabled(struct static_key *key) 128{ 129 int v; 130 131 STATIC_KEY_CHECK_USE(key); 132 /* 133 * Negative key->enabled has a special meaning: it sends 134 * static_key_slow_inc() down the slow path, and it is non-zero 135 * so it counts as "enabled" in jump_label_update(). Note that 136 * atomic_inc_unless_negative() checks >= 0, so roll our own. 137 */ 138 v = atomic_read(&key->enabled); 139 do { 140 if (v <= 0 || (v + 1) < 0) 141 return false; 142 } while (!likely(atomic_try_cmpxchg(&key->enabled, &v, v + 1))); 143 144 return true; 145} 146EXPORT_SYMBOL_GPL(static_key_fast_inc_not_disabled); 147 148bool static_key_slow_inc_cpuslocked(struct static_key *key) 149{ 150 lockdep_assert_cpus_held(); 151 152 /* 153 * Careful if we get concurrent static_key_slow_inc() calls; 154 * later calls must wait for the first one to _finish_ the 155 * jump_label_update() process. At the same time, however, 156 * the jump_label_update() call below wants to see 157 * static_key_enabled(&key) for jumps to be updated properly. 158 */ 159 if (static_key_fast_inc_not_disabled(key)) 160 return true; 161 162 jump_label_lock(); 163 if (atomic_read(&key->enabled) == 0) { 164 atomic_set(&key->enabled, -1); 165 jump_label_update(key); 166 /* 167 * Ensure that if the above cmpxchg loop observes our positive 168 * value, it must also observe all the text changes. 169 */ 170 atomic_set_release(&key->enabled, 1); 171 } else { 172 if (WARN_ON_ONCE(!static_key_fast_inc_not_disabled(key))) { 173 jump_label_unlock(); 174 return false; 175 } 176 } 177 jump_label_unlock(); 178 return true; 179} 180 181bool static_key_slow_inc(struct static_key *key) 182{ 183 bool ret; 184 185 cpus_read_lock(); 186 ret = static_key_slow_inc_cpuslocked(key); 187 cpus_read_unlock(); 188 return ret; 189} 190EXPORT_SYMBOL_GPL(static_key_slow_inc); 191 192void static_key_enable_cpuslocked(struct static_key *key) 193{ 194 STATIC_KEY_CHECK_USE(key); 195 lockdep_assert_cpus_held(); 196 197 if (atomic_read(&key->enabled) > 0) { 198 WARN_ON_ONCE(atomic_read(&key->enabled) != 1); 199 return; 200 } 201 202 jump_label_lock(); 203 if (atomic_read(&key->enabled) == 0) { 204 atomic_set(&key->enabled, -1); 205 jump_label_update(key); 206 /* 207 * See static_key_slow_inc(). 208 */ 209 atomic_set_release(&key->enabled, 1); 210 } 211 jump_label_unlock(); 212} 213EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked); 214 215void static_key_enable(struct static_key *key) 216{ 217 cpus_read_lock(); 218 static_key_enable_cpuslocked(key); 219 cpus_read_unlock(); 220} 221EXPORT_SYMBOL_GPL(static_key_enable); 222 223void static_key_disable_cpuslocked(struct static_key *key) 224{ 225 STATIC_KEY_CHECK_USE(key); 226 lockdep_assert_cpus_held(); 227 228 if (atomic_read(&key->enabled) != 1) { 229 WARN_ON_ONCE(atomic_read(&key->enabled) != 0); 230 return; 231 } 232 233 jump_label_lock(); 234 if (atomic_cmpxchg(&key->enabled, 1, 0)) 235 jump_label_update(key); 236 jump_label_unlock(); 237} 238EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked); 239 240void static_key_disable(struct static_key *key) 241{ 242 cpus_read_lock(); 243 static_key_disable_cpuslocked(key); 244 cpus_read_unlock(); 245} 246EXPORT_SYMBOL_GPL(static_key_disable); 247 248static bool static_key_slow_try_dec(struct static_key *key) 249{ 250 int val; 251 252 val = atomic_fetch_add_unless(&key->enabled, -1, 1); 253 if (val == 1) 254 return false; 255 256 /* 257 * The negative count check is valid even when a negative 258 * key->enabled is in use by static_key_slow_inc(); a 259 * __static_key_slow_dec() before the first static_key_slow_inc() 260 * returns is unbalanced, because all other static_key_slow_inc() 261 * instances block while the update is in progress. 262 */ 263 WARN(val < 0, "jump label: negative count!\n"); 264 return true; 265} 266 267static void __static_key_slow_dec_cpuslocked(struct static_key *key) 268{ 269 lockdep_assert_cpus_held(); 270 271 if (static_key_slow_try_dec(key)) 272 return; 273 274 jump_label_lock(); 275 if (atomic_dec_and_test(&key->enabled)) 276 jump_label_update(key); 277 jump_label_unlock(); 278} 279 280static void __static_key_slow_dec(struct static_key *key) 281{ 282 cpus_read_lock(); 283 __static_key_slow_dec_cpuslocked(key); 284 cpus_read_unlock(); 285} 286 287void jump_label_update_timeout(struct work_struct *work) 288{ 289 struct static_key_deferred *key = 290 container_of(work, struct static_key_deferred, work.work); 291 __static_key_slow_dec(&key->key); 292} 293EXPORT_SYMBOL_GPL(jump_label_update_timeout); 294 295void static_key_slow_dec(struct static_key *key) 296{ 297 STATIC_KEY_CHECK_USE(key); 298 __static_key_slow_dec(key); 299} 300EXPORT_SYMBOL_GPL(static_key_slow_dec); 301 302void static_key_slow_dec_cpuslocked(struct static_key *key) 303{ 304 STATIC_KEY_CHECK_USE(key); 305 __static_key_slow_dec_cpuslocked(key); 306} 307 308void __static_key_slow_dec_deferred(struct static_key *key, 309 struct delayed_work *work, 310 unsigned long timeout) 311{ 312 STATIC_KEY_CHECK_USE(key); 313 314 if (static_key_slow_try_dec(key)) 315 return; 316 317 schedule_delayed_work(work, timeout); 318} 319EXPORT_SYMBOL_GPL(__static_key_slow_dec_deferred); 320 321void __static_key_deferred_flush(void *key, struct delayed_work *work) 322{ 323 STATIC_KEY_CHECK_USE(key); 324 flush_delayed_work(work); 325} 326EXPORT_SYMBOL_GPL(__static_key_deferred_flush); 327 328void jump_label_rate_limit(struct static_key_deferred *key, 329 unsigned long rl) 330{ 331 STATIC_KEY_CHECK_USE(key); 332 key->timeout = rl; 333 INIT_DELAYED_WORK(&key->work, jump_label_update_timeout); 334} 335EXPORT_SYMBOL_GPL(jump_label_rate_limit); 336 337static int addr_conflict(struct jump_entry *entry, void *start, void *end) 338{ 339 if (jump_entry_code(entry) <= (unsigned long)end && 340 jump_entry_code(entry) + jump_entry_size(entry) > (unsigned long)start) 341 return 1; 342 343 return 0; 344} 345 346static int __jump_label_text_reserved(struct jump_entry *iter_start, 347 struct jump_entry *iter_stop, void *start, void *end, bool init) 348{ 349 struct jump_entry *iter; 350 351 iter = iter_start; 352 while (iter < iter_stop) { 353 if (init || !jump_entry_is_init(iter)) { 354 if (addr_conflict(iter, start, end)) 355 return 1; 356 } 357 iter++; 358 } 359 360 return 0; 361} 362 363#ifndef arch_jump_label_transform_static 364static void arch_jump_label_transform_static(struct jump_entry *entry, 365 enum jump_label_type type) 366{ 367 /* nothing to do on most architectures */ 368} 369#endif 370 371static inline struct jump_entry *static_key_entries(struct static_key *key) 372{ 373 WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED); 374 return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK); 375} 376 377static inline bool static_key_type(struct static_key *key) 378{ 379 return key->type & JUMP_TYPE_TRUE; 380} 381 382static inline bool static_key_linked(struct static_key *key) 383{ 384 return key->type & JUMP_TYPE_LINKED; 385} 386 387static inline void static_key_clear_linked(struct static_key *key) 388{ 389 key->type &= ~JUMP_TYPE_LINKED; 390} 391 392static inline void static_key_set_linked(struct static_key *key) 393{ 394 key->type |= JUMP_TYPE_LINKED; 395} 396 397/*** 398 * A 'struct static_key' uses a union such that it either points directly 399 * to a table of 'struct jump_entry' or to a linked list of modules which in 400 * turn point to 'struct jump_entry' tables. 401 * 402 * The two lower bits of the pointer are used to keep track of which pointer 403 * type is in use and to store the initial branch direction, we use an access 404 * function which preserves these bits. 405 */ 406static void static_key_set_entries(struct static_key *key, 407 struct jump_entry *entries) 408{ 409 unsigned long type; 410 411 WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK); 412 type = key->type & JUMP_TYPE_MASK; 413 key->entries = entries; 414 key->type |= type; 415} 416 417static enum jump_label_type jump_label_type(struct jump_entry *entry) 418{ 419 struct static_key *key = jump_entry_key(entry); 420 bool enabled = static_key_enabled(key); 421 bool branch = jump_entry_is_branch(entry); 422 423 /* See the comment in linux/jump_label.h */ 424 return enabled ^ branch; 425} 426 427static bool jump_label_can_update(struct jump_entry *entry, bool init) 428{ 429 /* 430 * Cannot update code that was in an init text area. 431 */ 432 if (!init && jump_entry_is_init(entry)) 433 return false; 434 435 if (!kernel_text_address(jump_entry_code(entry))) { 436 /* 437 * This skips patching built-in __exit, which 438 * is part of init_section_contains() but is 439 * not part of kernel_text_address(). 440 * 441 * Skipping built-in __exit is fine since it 442 * will never be executed. 443 */ 444 WARN_ONCE(!jump_entry_is_init(entry), 445 "can't patch jump_label at %pS", 446 (void *)jump_entry_code(entry)); 447 return false; 448 } 449 450 return true; 451} 452 453#ifndef HAVE_JUMP_LABEL_BATCH 454static void __jump_label_update(struct static_key *key, 455 struct jump_entry *entry, 456 struct jump_entry *stop, 457 bool init) 458{ 459 for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { 460 if (jump_label_can_update(entry, init)) 461 arch_jump_label_transform(entry, jump_label_type(entry)); 462 } 463} 464#else 465static void __jump_label_update(struct static_key *key, 466 struct jump_entry *entry, 467 struct jump_entry *stop, 468 bool init) 469{ 470 for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { 471 472 if (!jump_label_can_update(entry, init)) 473 continue; 474 475 if (!arch_jump_label_transform_queue(entry, jump_label_type(entry))) { 476 /* 477 * Queue is full: Apply the current queue and try again. 478 */ 479 arch_jump_label_transform_apply(); 480 BUG_ON(!arch_jump_label_transform_queue(entry, jump_label_type(entry))); 481 } 482 } 483 arch_jump_label_transform_apply(); 484} 485#endif 486 487void __init jump_label_init(void) 488{ 489 struct jump_entry *iter_start = __start___jump_table; 490 struct jump_entry *iter_stop = __stop___jump_table; 491 struct static_key *key = NULL; 492 struct jump_entry *iter; 493 494 /* 495 * Since we are initializing the static_key.enabled field with 496 * with the 'raw' int values (to avoid pulling in atomic.h) in 497 * jump_label.h, let's make sure that is safe. There are only two 498 * cases to check since we initialize to 0 or 1. 499 */ 500 BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0); 501 BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1); 502 503 if (static_key_initialized) 504 return; 505 506 cpus_read_lock(); 507 jump_label_lock(); 508 jump_label_sort_entries(iter_start, iter_stop); 509 510 for (iter = iter_start; iter < iter_stop; iter++) { 511 struct static_key *iterk; 512 bool in_init; 513 514 /* rewrite NOPs */ 515 if (jump_label_type(iter) == JUMP_LABEL_NOP) 516 arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); 517 518 in_init = init_section_contains((void *)jump_entry_code(iter), 1); 519 jump_entry_set_init(iter, in_init); 520 521 iterk = jump_entry_key(iter); 522 if (iterk == key) 523 continue; 524 525 key = iterk; 526 static_key_set_entries(key, iter); 527 } 528 static_key_initialized = true; 529 jump_label_unlock(); 530 cpus_read_unlock(); 531} 532 533#ifdef CONFIG_MODULES 534 535enum jump_label_type jump_label_init_type(struct jump_entry *entry) 536{ 537 struct static_key *key = jump_entry_key(entry); 538 bool type = static_key_type(key); 539 bool branch = jump_entry_is_branch(entry); 540 541 /* See the comment in linux/jump_label.h */ 542 return type ^ branch; 543} 544 545struct static_key_mod { 546 struct static_key_mod *next; 547 struct jump_entry *entries; 548 struct module *mod; 549}; 550 551static inline struct static_key_mod *static_key_mod(struct static_key *key) 552{ 553 WARN_ON_ONCE(!static_key_linked(key)); 554 return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK); 555} 556 557/*** 558 * key->type and key->next are the same via union. 559 * This sets key->next and preserves the type bits. 560 * 561 * See additional comments above static_key_set_entries(). 562 */ 563static void static_key_set_mod(struct static_key *key, 564 struct static_key_mod *mod) 565{ 566 unsigned long type; 567 568 WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK); 569 type = key->type & JUMP_TYPE_MASK; 570 key->next = mod; 571 key->type |= type; 572} 573 574static int __jump_label_mod_text_reserved(void *start, void *end) 575{ 576 struct module *mod; 577 int ret; 578 579 preempt_disable(); 580 mod = __module_text_address((unsigned long)start); 581 WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod); 582 if (!try_module_get(mod)) 583 mod = NULL; 584 preempt_enable(); 585 586 if (!mod) 587 return 0; 588 589 ret = __jump_label_text_reserved(mod->jump_entries, 590 mod->jump_entries + mod->num_jump_entries, 591 start, end, mod->state == MODULE_STATE_COMING); 592 593 module_put(mod); 594 595 return ret; 596} 597 598static void __jump_label_mod_update(struct static_key *key) 599{ 600 struct static_key_mod *mod; 601 602 for (mod = static_key_mod(key); mod; mod = mod->next) { 603 struct jump_entry *stop; 604 struct module *m; 605 606 /* 607 * NULL if the static_key is defined in a module 608 * that does not use it 609 */ 610 if (!mod->entries) 611 continue; 612 613 m = mod->mod; 614 if (!m) 615 stop = __stop___jump_table; 616 else 617 stop = m->jump_entries + m->num_jump_entries; 618 __jump_label_update(key, mod->entries, stop, 619 m && m->state == MODULE_STATE_COMING); 620 } 621} 622 623static int jump_label_add_module(struct module *mod) 624{ 625 struct jump_entry *iter_start = mod->jump_entries; 626 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; 627 struct jump_entry *iter; 628 struct static_key *key = NULL; 629 struct static_key_mod *jlm, *jlm2; 630 631 /* if the module doesn't have jump label entries, just return */ 632 if (iter_start == iter_stop) 633 return 0; 634 635 jump_label_sort_entries(iter_start, iter_stop); 636 637 for (iter = iter_start; iter < iter_stop; iter++) { 638 struct static_key *iterk; 639 bool in_init; 640 641 in_init = within_module_init(jump_entry_code(iter), mod); 642 jump_entry_set_init(iter, in_init); 643 644 iterk = jump_entry_key(iter); 645 if (iterk == key) 646 continue; 647 648 key = iterk; 649 if (within_module((unsigned long)key, mod)) { 650 static_key_set_entries(key, iter); 651 continue; 652 } 653 jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL); 654 if (!jlm) 655 return -ENOMEM; 656 if (!static_key_linked(key)) { 657 jlm2 = kzalloc(sizeof(struct static_key_mod), 658 GFP_KERNEL); 659 if (!jlm2) { 660 kfree(jlm); 661 return -ENOMEM; 662 } 663 preempt_disable(); 664 jlm2->mod = __module_address((unsigned long)key); 665 preempt_enable(); 666 jlm2->entries = static_key_entries(key); 667 jlm2->next = NULL; 668 static_key_set_mod(key, jlm2); 669 static_key_set_linked(key); 670 } 671 jlm->mod = mod; 672 jlm->entries = iter; 673 jlm->next = static_key_mod(key); 674 static_key_set_mod(key, jlm); 675 static_key_set_linked(key); 676 677 /* Only update if we've changed from our initial state */ 678 if (jump_label_type(iter) != jump_label_init_type(iter)) 679 __jump_label_update(key, iter, iter_stop, true); 680 } 681 682 return 0; 683} 684 685static void jump_label_del_module(struct module *mod) 686{ 687 struct jump_entry *iter_start = mod->jump_entries; 688 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; 689 struct jump_entry *iter; 690 struct static_key *key = NULL; 691 struct static_key_mod *jlm, **prev; 692 693 for (iter = iter_start; iter < iter_stop; iter++) { 694 if (jump_entry_key(iter) == key) 695 continue; 696 697 key = jump_entry_key(iter); 698 699 if (within_module((unsigned long)key, mod)) 700 continue; 701 702 /* No memory during module load */ 703 if (WARN_ON(!static_key_linked(key))) 704 continue; 705 706 prev = &key->next; 707 jlm = static_key_mod(key); 708 709 while (jlm && jlm->mod != mod) { 710 prev = &jlm->next; 711 jlm = jlm->next; 712 } 713 714 /* No memory during module load */ 715 if (WARN_ON(!jlm)) 716 continue; 717 718 if (prev == &key->next) 719 static_key_set_mod(key, jlm->next); 720 else 721 *prev = jlm->next; 722 723 kfree(jlm); 724 725 jlm = static_key_mod(key); 726 /* if only one etry is left, fold it back into the static_key */ 727 if (jlm->next == NULL) { 728 static_key_set_entries(key, jlm->entries); 729 static_key_clear_linked(key); 730 kfree(jlm); 731 } 732 } 733} 734 735static int 736jump_label_module_notify(struct notifier_block *self, unsigned long val, 737 void *data) 738{ 739 struct module *mod = data; 740 int ret = 0; 741 742 cpus_read_lock(); 743 jump_label_lock(); 744 745 switch (val) { 746 case MODULE_STATE_COMING: 747 ret = jump_label_add_module(mod); 748 if (ret) { 749 WARN(1, "Failed to allocate memory: jump_label may not work properly.\n"); 750 jump_label_del_module(mod); 751 } 752 break; 753 case MODULE_STATE_GOING: 754 jump_label_del_module(mod); 755 break; 756 } 757 758 jump_label_unlock(); 759 cpus_read_unlock(); 760 761 return notifier_from_errno(ret); 762} 763 764static struct notifier_block jump_label_module_nb = { 765 .notifier_call = jump_label_module_notify, 766 .priority = 1, /* higher than tracepoints */ 767}; 768 769static __init int jump_label_init_module(void) 770{ 771 return register_module_notifier(&jump_label_module_nb); 772} 773early_initcall(jump_label_init_module); 774 775#endif /* CONFIG_MODULES */ 776 777/*** 778 * jump_label_text_reserved - check if addr range is reserved 779 * @start: start text addr 780 * @end: end text addr 781 * 782 * checks if the text addr located between @start and @end 783 * overlaps with any of the jump label patch addresses. Code 784 * that wants to modify kernel text should first verify that 785 * it does not overlap with any of the jump label addresses. 786 * Caller must hold jump_label_mutex. 787 * 788 * returns 1 if there is an overlap, 0 otherwise 789 */ 790int jump_label_text_reserved(void *start, void *end) 791{ 792 bool init = system_state < SYSTEM_RUNNING; 793 int ret = __jump_label_text_reserved(__start___jump_table, 794 __stop___jump_table, start, end, init); 795 796 if (ret) 797 return ret; 798 799#ifdef CONFIG_MODULES 800 ret = __jump_label_mod_text_reserved(start, end); 801#endif 802 return ret; 803} 804 805static void jump_label_update(struct static_key *key) 806{ 807 struct jump_entry *stop = __stop___jump_table; 808 bool init = system_state < SYSTEM_RUNNING; 809 struct jump_entry *entry; 810#ifdef CONFIG_MODULES 811 struct module *mod; 812 813 if (static_key_linked(key)) { 814 __jump_label_mod_update(key); 815 return; 816 } 817 818 preempt_disable(); 819 mod = __module_address((unsigned long)key); 820 if (mod) { 821 stop = mod->jump_entries + mod->num_jump_entries; 822 init = mod->state == MODULE_STATE_COMING; 823 } 824 preempt_enable(); 825#endif 826 entry = static_key_entries(key); 827 /* if there are no users, entry can be NULL */ 828 if (entry) 829 __jump_label_update(key, entry, stop, init); 830} 831 832#ifdef CONFIG_STATIC_KEYS_SELFTEST 833static DEFINE_STATIC_KEY_TRUE(sk_true); 834static DEFINE_STATIC_KEY_FALSE(sk_false); 835 836static __init int jump_label_test(void) 837{ 838 int i; 839 840 for (i = 0; i < 2; i++) { 841 WARN_ON(static_key_enabled(&sk_true.key) != true); 842 WARN_ON(static_key_enabled(&sk_false.key) != false); 843 844 WARN_ON(!static_branch_likely(&sk_true)); 845 WARN_ON(!static_branch_unlikely(&sk_true)); 846 WARN_ON(static_branch_likely(&sk_false)); 847 WARN_ON(static_branch_unlikely(&sk_false)); 848 849 static_branch_disable(&sk_true); 850 static_branch_enable(&sk_false); 851 852 WARN_ON(static_key_enabled(&sk_true.key) == true); 853 WARN_ON(static_key_enabled(&sk_false.key) == false); 854 855 WARN_ON(static_branch_likely(&sk_true)); 856 WARN_ON(static_branch_unlikely(&sk_true)); 857 WARN_ON(!static_branch_likely(&sk_false)); 858 WARN_ON(!static_branch_unlikely(&sk_false)); 859 860 static_branch_enable(&sk_true); 861 static_branch_disable(&sk_false); 862 } 863 864 return 0; 865} 866early_initcall(jump_label_test); 867#endif /* STATIC_KEYS_SELFTEST */ 868