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 static 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_deferred(struct static_key_deferred *key) 233 { 234 STATIC_KEY_CHECK_USE(key); 235 __static_key_slow_dec(&key->key, key->timeout, &key->work); 236 } 237 EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred); 238 239 void static_key_deferred_flush(struct static_key_deferred *key) 240 { 241 STATIC_KEY_CHECK_USE(key); 242 flush_delayed_work(&key->work); 243 } 244 EXPORT_SYMBOL_GPL(static_key_deferred_flush); 245 246 void jump_label_rate_limit(struct static_key_deferred *key, 247 unsigned long rl) 248 { 249 STATIC_KEY_CHECK_USE(key); 250 key->timeout = rl; 251 INIT_DELAYED_WORK(&key->work, jump_label_update_timeout); 252 } 253 EXPORT_SYMBOL_GPL(jump_label_rate_limit); 254 255 static int addr_conflict(struct jump_entry *entry, void *start, void *end) 256 { 257 if (entry->code <= (unsigned long)end && 258 entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start) 259 return 1; 260 261 return 0; 262 } 263 264 static int __jump_label_text_reserved(struct jump_entry *iter_start, 265 struct jump_entry *iter_stop, void *start, void *end) 266 { 267 struct jump_entry *iter; 268 269 iter = iter_start; 270 while (iter < iter_stop) { 271 if (addr_conflict(iter, start, end)) 272 return 1; 273 iter++; 274 } 275 276 return 0; 277 } 278 279 /* 280 * Update code which is definitely not currently executing. 281 * Architectures which need heavyweight synchronization to modify 282 * running code can override this to make the non-live update case 283 * cheaper. 284 */ 285 void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry, 286 enum jump_label_type type) 287 { 288 arch_jump_label_transform(entry, type); 289 } 290 291 static inline struct jump_entry *static_key_entries(struct static_key *key) 292 { 293 WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED); 294 return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK); 295 } 296 297 static inline bool static_key_type(struct static_key *key) 298 { 299 return key->type & JUMP_TYPE_TRUE; 300 } 301 302 static inline bool static_key_linked(struct static_key *key) 303 { 304 return key->type & JUMP_TYPE_LINKED; 305 } 306 307 static inline void static_key_clear_linked(struct static_key *key) 308 { 309 key->type &= ~JUMP_TYPE_LINKED; 310 } 311 312 static inline void static_key_set_linked(struct static_key *key) 313 { 314 key->type |= JUMP_TYPE_LINKED; 315 } 316 317 static inline struct static_key *jump_entry_key(struct jump_entry *entry) 318 { 319 return (struct static_key *)((unsigned long)entry->key & ~1UL); 320 } 321 322 static bool jump_entry_branch(struct jump_entry *entry) 323 { 324 return (unsigned long)entry->key & 1UL; 325 } 326 327 /*** 328 * A 'struct static_key' uses a union such that it either points directly 329 * to a table of 'struct jump_entry' or to a linked list of modules which in 330 * turn point to 'struct jump_entry' tables. 331 * 332 * The two lower bits of the pointer are used to keep track of which pointer 333 * type is in use and to store the initial branch direction, we use an access 334 * function which preserves these bits. 335 */ 336 static void static_key_set_entries(struct static_key *key, 337 struct jump_entry *entries) 338 { 339 unsigned long type; 340 341 WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK); 342 type = key->type & JUMP_TYPE_MASK; 343 key->entries = entries; 344 key->type |= type; 345 } 346 347 static enum jump_label_type jump_label_type(struct jump_entry *entry) 348 { 349 struct static_key *key = jump_entry_key(entry); 350 bool enabled = static_key_enabled(key); 351 bool branch = jump_entry_branch(entry); 352 353 /* See the comment in linux/jump_label.h */ 354 return enabled ^ branch; 355 } 356 357 static void __jump_label_update(struct static_key *key, 358 struct jump_entry *entry, 359 struct jump_entry *stop) 360 { 361 for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { 362 /* 363 * entry->code set to 0 invalidates module init text sections 364 * kernel_text_address() verifies we are not in core kernel 365 * init code, see jump_label_invalidate_module_init(). 366 */ 367 if (entry->code && kernel_text_address(entry->code)) 368 arch_jump_label_transform(entry, jump_label_type(entry)); 369 } 370 } 371 372 void __init jump_label_init(void) 373 { 374 struct jump_entry *iter_start = __start___jump_table; 375 struct jump_entry *iter_stop = __stop___jump_table; 376 struct static_key *key = NULL; 377 struct jump_entry *iter; 378 379 /* 380 * Since we are initializing the static_key.enabled field with 381 * with the 'raw' int values (to avoid pulling in atomic.h) in 382 * jump_label.h, let's make sure that is safe. There are only two 383 * cases to check since we initialize to 0 or 1. 384 */ 385 BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0); 386 BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1); 387 388 if (static_key_initialized) 389 return; 390 391 cpus_read_lock(); 392 jump_label_lock(); 393 jump_label_sort_entries(iter_start, iter_stop); 394 395 for (iter = iter_start; iter < iter_stop; iter++) { 396 struct static_key *iterk; 397 398 /* rewrite NOPs */ 399 if (jump_label_type(iter) == JUMP_LABEL_NOP) 400 arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); 401 402 iterk = jump_entry_key(iter); 403 if (iterk == key) 404 continue; 405 406 key = iterk; 407 static_key_set_entries(key, iter); 408 } 409 static_key_initialized = true; 410 jump_label_unlock(); 411 cpus_read_unlock(); 412 } 413 414 #ifdef CONFIG_MODULES 415 416 static enum jump_label_type jump_label_init_type(struct jump_entry *entry) 417 { 418 struct static_key *key = jump_entry_key(entry); 419 bool type = static_key_type(key); 420 bool branch = jump_entry_branch(entry); 421 422 /* See the comment in linux/jump_label.h */ 423 return type ^ branch; 424 } 425 426 struct static_key_mod { 427 struct static_key_mod *next; 428 struct jump_entry *entries; 429 struct module *mod; 430 }; 431 432 static inline struct static_key_mod *static_key_mod(struct static_key *key) 433 { 434 WARN_ON_ONCE(!(key->type & JUMP_TYPE_LINKED)); 435 return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK); 436 } 437 438 /*** 439 * key->type and key->next are the same via union. 440 * This sets key->next and preserves the type bits. 441 * 442 * See additional comments above static_key_set_entries(). 443 */ 444 static void static_key_set_mod(struct static_key *key, 445 struct static_key_mod *mod) 446 { 447 unsigned long type; 448 449 WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK); 450 type = key->type & JUMP_TYPE_MASK; 451 key->next = mod; 452 key->type |= type; 453 } 454 455 static int __jump_label_mod_text_reserved(void *start, void *end) 456 { 457 struct module *mod; 458 459 preempt_disable(); 460 mod = __module_text_address((unsigned long)start); 461 WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod); 462 preempt_enable(); 463 464 if (!mod) 465 return 0; 466 467 468 return __jump_label_text_reserved(mod->jump_entries, 469 mod->jump_entries + mod->num_jump_entries, 470 start, end); 471 } 472 473 static void __jump_label_mod_update(struct static_key *key) 474 { 475 struct static_key_mod *mod; 476 477 for (mod = static_key_mod(key); mod; mod = mod->next) { 478 struct jump_entry *stop; 479 struct module *m; 480 481 /* 482 * NULL if the static_key is defined in a module 483 * that does not use it 484 */ 485 if (!mod->entries) 486 continue; 487 488 m = mod->mod; 489 if (!m) 490 stop = __stop___jump_table; 491 else 492 stop = m->jump_entries + m->num_jump_entries; 493 __jump_label_update(key, mod->entries, stop); 494 } 495 } 496 497 /*** 498 * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop() 499 * @mod: module to patch 500 * 501 * Allow for run-time selection of the optimal nops. Before the module 502 * loads patch these with arch_get_jump_label_nop(), which is specified by 503 * the arch specific jump label code. 504 */ 505 void jump_label_apply_nops(struct module *mod) 506 { 507 struct jump_entry *iter_start = mod->jump_entries; 508 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; 509 struct jump_entry *iter; 510 511 /* if the module doesn't have jump label entries, just return */ 512 if (iter_start == iter_stop) 513 return; 514 515 for (iter = iter_start; iter < iter_stop; iter++) { 516 /* Only write NOPs for arch_branch_static(). */ 517 if (jump_label_init_type(iter) == JUMP_LABEL_NOP) 518 arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); 519 } 520 } 521 522 static int jump_label_add_module(struct module *mod) 523 { 524 struct jump_entry *iter_start = mod->jump_entries; 525 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; 526 struct jump_entry *iter; 527 struct static_key *key = NULL; 528 struct static_key_mod *jlm, *jlm2; 529 530 /* if the module doesn't have jump label entries, just return */ 531 if (iter_start == iter_stop) 532 return 0; 533 534 jump_label_sort_entries(iter_start, iter_stop); 535 536 for (iter = iter_start; iter < iter_stop; iter++) { 537 struct static_key *iterk; 538 539 iterk = jump_entry_key(iter); 540 if (iterk == key) 541 continue; 542 543 key = iterk; 544 if (within_module(iter->key, mod)) { 545 static_key_set_entries(key, iter); 546 continue; 547 } 548 jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL); 549 if (!jlm) 550 return -ENOMEM; 551 if (!static_key_linked(key)) { 552 jlm2 = kzalloc(sizeof(struct static_key_mod), 553 GFP_KERNEL); 554 if (!jlm2) { 555 kfree(jlm); 556 return -ENOMEM; 557 } 558 preempt_disable(); 559 jlm2->mod = __module_address((unsigned long)key); 560 preempt_enable(); 561 jlm2->entries = static_key_entries(key); 562 jlm2->next = NULL; 563 static_key_set_mod(key, jlm2); 564 static_key_set_linked(key); 565 } 566 jlm->mod = mod; 567 jlm->entries = iter; 568 jlm->next = static_key_mod(key); 569 static_key_set_mod(key, jlm); 570 static_key_set_linked(key); 571 572 /* Only update if we've changed from our initial state */ 573 if (jump_label_type(iter) != jump_label_init_type(iter)) 574 __jump_label_update(key, iter, iter_stop); 575 } 576 577 return 0; 578 } 579 580 static void jump_label_del_module(struct module *mod) 581 { 582 struct jump_entry *iter_start = mod->jump_entries; 583 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; 584 struct jump_entry *iter; 585 struct static_key *key = NULL; 586 struct static_key_mod *jlm, **prev; 587 588 for (iter = iter_start; iter < iter_stop; iter++) { 589 if (jump_entry_key(iter) == key) 590 continue; 591 592 key = jump_entry_key(iter); 593 594 if (within_module(iter->key, mod)) 595 continue; 596 597 /* No memory during module load */ 598 if (WARN_ON(!static_key_linked(key))) 599 continue; 600 601 prev = &key->next; 602 jlm = static_key_mod(key); 603 604 while (jlm && jlm->mod != mod) { 605 prev = &jlm->next; 606 jlm = jlm->next; 607 } 608 609 /* No memory during module load */ 610 if (WARN_ON(!jlm)) 611 continue; 612 613 if (prev == &key->next) 614 static_key_set_mod(key, jlm->next); 615 else 616 *prev = jlm->next; 617 618 kfree(jlm); 619 620 jlm = static_key_mod(key); 621 /* if only one etry is left, fold it back into the static_key */ 622 if (jlm->next == NULL) { 623 static_key_set_entries(key, jlm->entries); 624 static_key_clear_linked(key); 625 kfree(jlm); 626 } 627 } 628 } 629 630 static void jump_label_invalidate_module_init(struct module *mod) 631 { 632 struct jump_entry *iter_start = mod->jump_entries; 633 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; 634 struct jump_entry *iter; 635 636 for (iter = iter_start; iter < iter_stop; iter++) { 637 if (within_module_init(iter->code, mod)) 638 iter->code = 0; 639 } 640 } 641 642 static int 643 jump_label_module_notify(struct notifier_block *self, unsigned long val, 644 void *data) 645 { 646 struct module *mod = data; 647 int ret = 0; 648 649 cpus_read_lock(); 650 jump_label_lock(); 651 652 switch (val) { 653 case MODULE_STATE_COMING: 654 ret = jump_label_add_module(mod); 655 if (ret) { 656 WARN(1, "Failed to allocatote memory: jump_label may not work properly.\n"); 657 jump_label_del_module(mod); 658 } 659 break; 660 case MODULE_STATE_GOING: 661 jump_label_del_module(mod); 662 break; 663 case MODULE_STATE_LIVE: 664 jump_label_invalidate_module_init(mod); 665 break; 666 } 667 668 jump_label_unlock(); 669 cpus_read_unlock(); 670 671 return notifier_from_errno(ret); 672 } 673 674 static struct notifier_block jump_label_module_nb = { 675 .notifier_call = jump_label_module_notify, 676 .priority = 1, /* higher than tracepoints */ 677 }; 678 679 static __init int jump_label_init_module(void) 680 { 681 return register_module_notifier(&jump_label_module_nb); 682 } 683 early_initcall(jump_label_init_module); 684 685 #endif /* CONFIG_MODULES */ 686 687 /*** 688 * jump_label_text_reserved - check if addr range is reserved 689 * @start: start text addr 690 * @end: end text addr 691 * 692 * checks if the text addr located between @start and @end 693 * overlaps with any of the jump label patch addresses. Code 694 * that wants to modify kernel text should first verify that 695 * it does not overlap with any of the jump label addresses. 696 * Caller must hold jump_label_mutex. 697 * 698 * returns 1 if there is an overlap, 0 otherwise 699 */ 700 int jump_label_text_reserved(void *start, void *end) 701 { 702 int ret = __jump_label_text_reserved(__start___jump_table, 703 __stop___jump_table, start, end); 704 705 if (ret) 706 return ret; 707 708 #ifdef CONFIG_MODULES 709 ret = __jump_label_mod_text_reserved(start, end); 710 #endif 711 return ret; 712 } 713 714 static void jump_label_update(struct static_key *key) 715 { 716 struct jump_entry *stop = __stop___jump_table; 717 struct jump_entry *entry; 718 #ifdef CONFIG_MODULES 719 struct module *mod; 720 721 if (static_key_linked(key)) { 722 __jump_label_mod_update(key); 723 return; 724 } 725 726 preempt_disable(); 727 mod = __module_address((unsigned long)key); 728 if (mod) 729 stop = mod->jump_entries + mod->num_jump_entries; 730 preempt_enable(); 731 #endif 732 entry = static_key_entries(key); 733 /* if there are no users, entry can be NULL */ 734 if (entry) 735 __jump_label_update(key, entry, stop); 736 } 737 738 #ifdef CONFIG_STATIC_KEYS_SELFTEST 739 static DEFINE_STATIC_KEY_TRUE(sk_true); 740 static DEFINE_STATIC_KEY_FALSE(sk_false); 741 742 static __init int jump_label_test(void) 743 { 744 int i; 745 746 for (i = 0; i < 2; i++) { 747 WARN_ON(static_key_enabled(&sk_true.key) != true); 748 WARN_ON(static_key_enabled(&sk_false.key) != false); 749 750 WARN_ON(!static_branch_likely(&sk_true)); 751 WARN_ON(!static_branch_unlikely(&sk_true)); 752 WARN_ON(static_branch_likely(&sk_false)); 753 WARN_ON(static_branch_unlikely(&sk_false)); 754 755 static_branch_disable(&sk_true); 756 static_branch_enable(&sk_false); 757 758 WARN_ON(static_key_enabled(&sk_true.key) == true); 759 WARN_ON(static_key_enabled(&sk_false.key) == false); 760 761 WARN_ON(static_branch_likely(&sk_true)); 762 WARN_ON(static_branch_unlikely(&sk_true)); 763 WARN_ON(!static_branch_likely(&sk_false)); 764 WARN_ON(!static_branch_unlikely(&sk_false)); 765 766 static_branch_enable(&sk_true); 767 static_branch_disable(&sk_false); 768 } 769 770 return 0; 771 } 772 early_initcall(jump_label_test); 773 #endif /* STATIC_KEYS_SELFTEST */ 774 775 #endif /* HAVE_JUMP_LABEL */ 776