| 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 */ |
| 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 | /* |
| 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 | |
| 63 | static 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 | |
| 79 | static void |
| 80 | jump_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 | |
| 93 | static 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 | */ |
| 104 | int 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 | } |
| 114 | EXPORT_SYMBOL_GPL(static_key_count); |
| 115 | |
| 116 | void static_key_slow_inc_cpuslocked(struct static_key *key) |
| 117 | { |
| 118 | int v, v1; |
| 119 | |
| 120 | STATIC_KEY_CHECK_USE(key); |
| 121 | lockdep_assert_cpus_held(); |
| 122 | |
| 123 | /* |
| 124 | * Careful if we get concurrent static_key_slow_inc() calls; |
| 125 | * later calls must wait for the first one to _finish_ the |
| 126 | * jump_label_update() process. At the same time, however, |
| 127 | * the jump_label_update() call below wants to see |
| 128 | * static_key_enabled(&key) for jumps to be updated properly. |
| 129 | * |
| 130 | * So give a special meaning to negative key->enabled: it sends |
| 131 | * static_key_slow_inc() down the slow path, and it is non-zero |
| 132 | * so it counts as "enabled" in jump_label_update(). Note that |
| 133 | * atomic_inc_unless_negative() checks >= 0, so roll our own. |
| 134 | */ |
| 135 | for (v = atomic_read(&key->enabled); v > 0; v = v1) { |
| 136 | v1 = atomic_cmpxchg(&key->enabled, v, v + 1); |
| 137 | if (likely(v1 == v)) |
| 138 | return; |
| 139 | } |
| 140 | |
| 141 | jump_label_lock(); |
| 142 | if (atomic_read(&key->enabled) == 0) { |
| 143 | atomic_set(&key->enabled, -1); |
| 144 | jump_label_update(key); |
| 145 | /* |
| 146 | * Ensure that if the above cmpxchg loop observes our positive |
| 147 | * value, it must also observe all the text changes. |
| 148 | */ |
| 149 | atomic_set_release(&key->enabled, 1); |
| 150 | } else { |
| 151 | atomic_inc(&key->enabled); |
| 152 | } |
| 153 | jump_label_unlock(); |
| 154 | } |
| 155 | |
| 156 | void static_key_slow_inc(struct static_key *key) |
| 157 | { |
| 158 | cpus_read_lock(); |
| 159 | static_key_slow_inc_cpuslocked(key); |
| 160 | cpus_read_unlock(); |
| 161 | } |
| 162 | EXPORT_SYMBOL_GPL(static_key_slow_inc); |
| 163 | |
| 164 | void static_key_enable_cpuslocked(struct static_key *key) |
| 165 | { |
| 166 | STATIC_KEY_CHECK_USE(key); |
| 167 | lockdep_assert_cpus_held(); |
| 168 | |
| 169 | if (atomic_read(&key->enabled) > 0) { |
| 170 | WARN_ON_ONCE(atomic_read(&key->enabled) != 1); |
| 171 | return; |
| 172 | } |
| 173 | |
| 174 | jump_label_lock(); |
| 175 | if (atomic_read(&key->enabled) == 0) { |
| 176 | atomic_set(&key->enabled, -1); |
| 177 | jump_label_update(key); |
| 178 | /* |
| 179 | * See static_key_slow_inc(). |
| 180 | */ |
| 181 | atomic_set_release(&key->enabled, 1); |
| 182 | } |
| 183 | jump_label_unlock(); |
| 184 | } |
| 185 | EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked); |
| 186 | |
| 187 | void static_key_enable(struct static_key *key) |
| 188 | { |
| 189 | cpus_read_lock(); |
| 190 | static_key_enable_cpuslocked(key); |
| 191 | cpus_read_unlock(); |
| 192 | } |
| 193 | EXPORT_SYMBOL_GPL(static_key_enable); |
| 194 | |
| 195 | void static_key_disable_cpuslocked(struct static_key *key) |
| 196 | { |
| 197 | STATIC_KEY_CHECK_USE(key); |
| 198 | lockdep_assert_cpus_held(); |
| 199 | |
| 200 | if (atomic_read(&key->enabled) != 1) { |
| 201 | WARN_ON_ONCE(atomic_read(&key->enabled) != 0); |
| 202 | return; |
| 203 | } |
| 204 | |
| 205 | jump_label_lock(); |
| 206 | if (atomic_cmpxchg(&key->enabled, 1, 0)) |
| 207 | jump_label_update(key); |
| 208 | jump_label_unlock(); |
| 209 | } |
| 210 | EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked); |
| 211 | |
| 212 | void static_key_disable(struct static_key *key) |
| 213 | { |
| 214 | cpus_read_lock(); |
| 215 | static_key_disable_cpuslocked(key); |
| 216 | cpus_read_unlock(); |
| 217 | } |
| 218 | EXPORT_SYMBOL_GPL(static_key_disable); |
| 219 | |
| 220 | static bool static_key_slow_try_dec(struct static_key *key) |
| 221 | { |
| 222 | int val; |
| 223 | |
| 224 | val = atomic_fetch_add_unless(&key->enabled, -1, 1); |
| 225 | if (val == 1) |
| 226 | return false; |
| 227 | |
| 228 | /* |
| 229 | * The negative count check is valid even when a negative |
| 230 | * key->enabled is in use by static_key_slow_inc(); a |
| 231 | * __static_key_slow_dec() before the first static_key_slow_inc() |
| 232 | * returns is unbalanced, because all other static_key_slow_inc() |
| 233 | * instances block while the update is in progress. |
| 234 | */ |
| 235 | WARN(val < 0, "jump label: negative count!\n"); |
| 236 | return true; |
| 237 | } |
| 238 | |
| 239 | static void __static_key_slow_dec_cpuslocked(struct static_key *key) |
| 240 | { |
| 241 | lockdep_assert_cpus_held(); |
| 242 | |
| 243 | if (static_key_slow_try_dec(key)) |
| 244 | return; |
| 245 | |
| 246 | jump_label_lock(); |
| 247 | if (atomic_dec_and_test(&key->enabled)) |
| 248 | jump_label_update(key); |
| 249 | jump_label_unlock(); |
| 250 | } |
| 251 | |
| 252 | static void __static_key_slow_dec(struct static_key *key) |
| 253 | { |
| 254 | cpus_read_lock(); |
| 255 | __static_key_slow_dec_cpuslocked(key); |
| 256 | cpus_read_unlock(); |
| 257 | } |
| 258 | |
| 259 | void jump_label_update_timeout(struct work_struct *work) |
| 260 | { |
| 261 | struct static_key_deferred *key = |
| 262 | container_of(work, struct static_key_deferred, work.work); |
| 263 | __static_key_slow_dec(&key->key); |
| 264 | } |
| 265 | EXPORT_SYMBOL_GPL(jump_label_update_timeout); |
| 266 | |
| 267 | void static_key_slow_dec(struct static_key *key) |
| 268 | { |
| 269 | STATIC_KEY_CHECK_USE(key); |
| 270 | __static_key_slow_dec(key); |
| 271 | } |
| 272 | EXPORT_SYMBOL_GPL(static_key_slow_dec); |
| 273 | |
| 274 | void static_key_slow_dec_cpuslocked(struct static_key *key) |
| 275 | { |
| 276 | STATIC_KEY_CHECK_USE(key); |
| 277 | __static_key_slow_dec_cpuslocked(key); |
| 278 | } |
| 279 | |
| 280 | void __static_key_slow_dec_deferred(struct static_key *key, |
| 281 | struct delayed_work *work, |
| 282 | unsigned long timeout) |
| 283 | { |
| 284 | STATIC_KEY_CHECK_USE(key); |
| 285 | |
| 286 | if (static_key_slow_try_dec(key)) |
| 287 | return; |
| 288 | |
| 289 | schedule_delayed_work(work, timeout); |
| 290 | } |
| 291 | EXPORT_SYMBOL_GPL(__static_key_slow_dec_deferred); |
| 292 | |
| 293 | void __static_key_deferred_flush(void *key, struct delayed_work *work) |
| 294 | { |
| 295 | STATIC_KEY_CHECK_USE(key); |
| 296 | flush_delayed_work(work); |
| 297 | } |
| 298 | EXPORT_SYMBOL_GPL(__static_key_deferred_flush); |
| 299 | |
| 300 | void jump_label_rate_limit(struct static_key_deferred *key, |
| 301 | unsigned long rl) |
| 302 | { |
| 303 | STATIC_KEY_CHECK_USE(key); |
| 304 | key->timeout = rl; |
| 305 | INIT_DELAYED_WORK(&key->work, jump_label_update_timeout); |
| 306 | } |
| 307 | EXPORT_SYMBOL_GPL(jump_label_rate_limit); |
| 308 | |
| 309 | static int addr_conflict(struct jump_entry *entry, void *start, void *end) |
| 310 | { |
| 311 | if (jump_entry_code(entry) <= (unsigned long)end && |
| 312 | jump_entry_code(entry) + jump_entry_size(entry) > (unsigned long)start) |
| 313 | return 1; |
| 314 | |
| 315 | return 0; |
| 316 | } |
| 317 | |
| 318 | static int __jump_label_text_reserved(struct jump_entry *iter_start, |
| 319 | struct jump_entry *iter_stop, void *start, void *end, bool init) |
| 320 | { |
| 321 | struct jump_entry *iter; |
| 322 | |
| 323 | iter = iter_start; |
| 324 | while (iter < iter_stop) { |
| 325 | if (init || !jump_entry_is_init(iter)) { |
| 326 | if (addr_conflict(iter, start, end)) |
| 327 | return 1; |
| 328 | } |
| 329 | iter++; |
| 330 | } |
| 331 | |
| 332 | return 0; |
| 333 | } |
| 334 | |
| 335 | #ifndef arch_jump_label_transform_static |
| 336 | static void arch_jump_label_transform_static(struct jump_entry *entry, |
| 337 | enum jump_label_type type) |
| 338 | { |
| 339 | /* nothing to do on most architectures */ |
| 340 | } |
| 341 | #endif |
| 342 | |
| 343 | static inline struct jump_entry *static_key_entries(struct static_key *key) |
| 344 | { |
| 345 | WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED); |
| 346 | return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK); |
| 347 | } |
| 348 | |
| 349 | static inline bool static_key_type(struct static_key *key) |
| 350 | { |
| 351 | return key->type & JUMP_TYPE_TRUE; |
| 352 | } |
| 353 | |
| 354 | static inline bool static_key_linked(struct static_key *key) |
| 355 | { |
| 356 | return key->type & JUMP_TYPE_LINKED; |
| 357 | } |
| 358 | |
| 359 | static inline void static_key_clear_linked(struct static_key *key) |
| 360 | { |
| 361 | key->type &= ~JUMP_TYPE_LINKED; |
| 362 | } |
| 363 | |
| 364 | static inline void static_key_set_linked(struct static_key *key) |
| 365 | { |
| 366 | key->type |= JUMP_TYPE_LINKED; |
| 367 | } |
| 368 | |
| 369 | /*** |
| 370 | * A 'struct static_key' uses a union such that it either points directly |
| 371 | * to a table of 'struct jump_entry' or to a linked list of modules which in |
| 372 | * turn point to 'struct jump_entry' tables. |
| 373 | * |
| 374 | * The two lower bits of the pointer are used to keep track of which pointer |
| 375 | * type is in use and to store the initial branch direction, we use an access |
| 376 | * function which preserves these bits. |
| 377 | */ |
| 378 | static void static_key_set_entries(struct static_key *key, |
| 379 | struct jump_entry *entries) |
| 380 | { |
| 381 | unsigned long type; |
| 382 | |
| 383 | WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK); |
| 384 | type = key->type & JUMP_TYPE_MASK; |
| 385 | key->entries = entries; |
| 386 | key->type |= type; |
| 387 | } |
| 388 | |
| 389 | static enum jump_label_type jump_label_type(struct jump_entry *entry) |
| 390 | { |
| 391 | struct static_key *key = jump_entry_key(entry); |
| 392 | bool enabled = static_key_enabled(key); |
| 393 | bool branch = jump_entry_is_branch(entry); |
| 394 | |
| 395 | /* See the comment in linux/jump_label.h */ |
| 396 | return enabled ^ branch; |
| 397 | } |
| 398 | |
| 399 | static bool jump_label_can_update(struct jump_entry *entry, bool init) |
| 400 | { |
| 401 | /* |
| 402 | * Cannot update code that was in an init text area. |
| 403 | */ |
| 404 | if (!init && jump_entry_is_init(entry)) |
| 405 | return false; |
| 406 | |
| 407 | if (!kernel_text_address(jump_entry_code(entry))) { |
| 408 | /* |
| 409 | * This skips patching built-in __exit, which |
| 410 | * is part of init_section_contains() but is |
| 411 | * not part of kernel_text_address(). |
| 412 | * |
| 413 | * Skipping built-in __exit is fine since it |
| 414 | * will never be executed. |
| 415 | */ |
| 416 | WARN_ONCE(!jump_entry_is_init(entry), |
| 417 | "can't patch jump_label at %pS", |
| 418 | (void *)jump_entry_code(entry)); |
| 419 | return false; |
| 420 | } |
| 421 | |
| 422 | return true; |
| 423 | } |
| 424 | |
| 425 | #ifndef HAVE_JUMP_LABEL_BATCH |
| 426 | static void __jump_label_update(struct static_key *key, |
| 427 | struct jump_entry *entry, |
| 428 | struct jump_entry *stop, |
| 429 | bool init) |
| 430 | { |
| 431 | for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { |
| 432 | if (jump_label_can_update(entry, init)) |
| 433 | arch_jump_label_transform(entry, jump_label_type(entry)); |
| 434 | } |
| 435 | } |
| 436 | #else |
| 437 | static void __jump_label_update(struct static_key *key, |
| 438 | struct jump_entry *entry, |
| 439 | struct jump_entry *stop, |
| 440 | bool init) |
| 441 | { |
| 442 | for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { |
| 443 | |
| 444 | if (!jump_label_can_update(entry, init)) |
| 445 | continue; |
| 446 | |
| 447 | if (!arch_jump_label_transform_queue(entry, jump_label_type(entry))) { |
| 448 | /* |
| 449 | * Queue is full: Apply the current queue and try again. |
| 450 | */ |
| 451 | arch_jump_label_transform_apply(); |
| 452 | BUG_ON(!arch_jump_label_transform_queue(entry, jump_label_type(entry))); |
| 453 | } |
| 454 | } |
| 455 | arch_jump_label_transform_apply(); |
| 456 | } |
| 457 | #endif |
| 458 | |
| 459 | void __init jump_label_init(void) |
| 460 | { |
| 461 | struct jump_entry *iter_start = __start___jump_table; |
| 462 | struct jump_entry *iter_stop = __stop___jump_table; |
| 463 | struct static_key *key = NULL; |
| 464 | struct jump_entry *iter; |
| 465 | |
| 466 | /* |
| 467 | * Since we are initializing the static_key.enabled field with |
| 468 | * with the 'raw' int values (to avoid pulling in atomic.h) in |
| 469 | * jump_label.h, let's make sure that is safe. There are only two |
| 470 | * cases to check since we initialize to 0 or 1. |
| 471 | */ |
| 472 | BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0); |
| 473 | BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1); |
| 474 | |
| 475 | if (static_key_initialized) |
| 476 | return; |
| 477 | |
| 478 | cpus_read_lock(); |
| 479 | jump_label_lock(); |
| 480 | jump_label_sort_entries(iter_start, iter_stop); |
| 481 | |
| 482 | for (iter = iter_start; iter < iter_stop; iter++) { |
| 483 | struct static_key *iterk; |
| 484 | bool in_init; |
| 485 | |
| 486 | /* rewrite NOPs */ |
| 487 | if (jump_label_type(iter) == JUMP_LABEL_NOP) |
| 488 | arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); |
| 489 | |
| 490 | in_init = init_section_contains((void *)jump_entry_code(iter), 1); |
| 491 | jump_entry_set_init(iter, in_init); |
| 492 | |
| 493 | iterk = jump_entry_key(iter); |
| 494 | if (iterk == key) |
| 495 | continue; |
| 496 | |
| 497 | key = iterk; |
| 498 | static_key_set_entries(key, iter); |
| 499 | } |
| 500 | static_key_initialized = true; |
| 501 | jump_label_unlock(); |
| 502 | cpus_read_unlock(); |
| 503 | } |
| 504 | |
| 505 | #ifdef CONFIG_MODULES |
| 506 | |
| 507 | enum jump_label_type jump_label_init_type(struct jump_entry *entry) |
| 508 | { |
| 509 | struct static_key *key = jump_entry_key(entry); |
| 510 | bool type = static_key_type(key); |
| 511 | bool branch = jump_entry_is_branch(entry); |
| 512 | |
| 513 | /* See the comment in linux/jump_label.h */ |
| 514 | return type ^ branch; |
| 515 | } |
| 516 | |
| 517 | struct static_key_mod { |
| 518 | struct static_key_mod *next; |
| 519 | struct jump_entry *entries; |
| 520 | struct module *mod; |
| 521 | }; |
| 522 | |
| 523 | static inline struct static_key_mod *static_key_mod(struct static_key *key) |
| 524 | { |
| 525 | WARN_ON_ONCE(!static_key_linked(key)); |
| 526 | return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK); |
| 527 | } |
| 528 | |
| 529 | /*** |
| 530 | * key->type and key->next are the same via union. |
| 531 | * This sets key->next and preserves the type bits. |
| 532 | * |
| 533 | * See additional comments above static_key_set_entries(). |
| 534 | */ |
| 535 | static void static_key_set_mod(struct static_key *key, |
| 536 | struct static_key_mod *mod) |
| 537 | { |
| 538 | unsigned long type; |
| 539 | |
| 540 | WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK); |
| 541 | type = key->type & JUMP_TYPE_MASK; |
| 542 | key->next = mod; |
| 543 | key->type |= type; |
| 544 | } |
| 545 | |
| 546 | static int __jump_label_mod_text_reserved(void *start, void *end) |
| 547 | { |
| 548 | struct module *mod; |
| 549 | int ret; |
| 550 | |
| 551 | preempt_disable(); |
| 552 | mod = __module_text_address((unsigned long)start); |
| 553 | WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod); |
| 554 | if (!try_module_get(mod)) |
| 555 | mod = NULL; |
| 556 | preempt_enable(); |
| 557 | |
| 558 | if (!mod) |
| 559 | return 0; |
| 560 | |
| 561 | ret = __jump_label_text_reserved(mod->jump_entries, |
| 562 | mod->jump_entries + mod->num_jump_entries, |
| 563 | start, end, mod->state == MODULE_STATE_COMING); |
| 564 | |
| 565 | module_put(mod); |
| 566 | |
| 567 | return ret; |
| 568 | } |
| 569 | |
| 570 | static void __jump_label_mod_update(struct static_key *key) |
| 571 | { |
| 572 | struct static_key_mod *mod; |
| 573 | |
| 574 | for (mod = static_key_mod(key); mod; mod = mod->next) { |
| 575 | struct jump_entry *stop; |
| 576 | struct module *m; |
| 577 | |
| 578 | /* |
| 579 | * NULL if the static_key is defined in a module |
| 580 | * that does not use it |
| 581 | */ |
| 582 | if (!mod->entries) |
| 583 | continue; |
| 584 | |
| 585 | m = mod->mod; |
| 586 | if (!m) |
| 587 | stop = __stop___jump_table; |
| 588 | else |
| 589 | stop = m->jump_entries + m->num_jump_entries; |
| 590 | __jump_label_update(key, mod->entries, stop, |
| 591 | m && m->state == MODULE_STATE_COMING); |
| 592 | } |
| 593 | } |
| 594 | |
| 595 | static int jump_label_add_module(struct module *mod) |
| 596 | { |
| 597 | struct jump_entry *iter_start = mod->jump_entries; |
| 598 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; |
| 599 | struct jump_entry *iter; |
| 600 | struct static_key *key = NULL; |
| 601 | struct static_key_mod *jlm, *jlm2; |
| 602 | |
| 603 | /* if the module doesn't have jump label entries, just return */ |
| 604 | if (iter_start == iter_stop) |
| 605 | return 0; |
| 606 | |
| 607 | jump_label_sort_entries(iter_start, iter_stop); |
| 608 | |
| 609 | for (iter = iter_start; iter < iter_stop; iter++) { |
| 610 | struct static_key *iterk; |
| 611 | bool in_init; |
| 612 | |
| 613 | in_init = within_module_init(jump_entry_code(iter), mod); |
| 614 | jump_entry_set_init(iter, in_init); |
| 615 | |
| 616 | iterk = jump_entry_key(iter); |
| 617 | if (iterk == key) |
| 618 | continue; |
| 619 | |
| 620 | key = iterk; |
| 621 | if (within_module((unsigned long)key, mod)) { |
| 622 | static_key_set_entries(key, iter); |
| 623 | continue; |
| 624 | } |
| 625 | jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL); |
| 626 | if (!jlm) |
| 627 | return -ENOMEM; |
| 628 | if (!static_key_linked(key)) { |
| 629 | jlm2 = kzalloc(sizeof(struct static_key_mod), |
| 630 | GFP_KERNEL); |
| 631 | if (!jlm2) { |
| 632 | kfree(jlm); |
| 633 | return -ENOMEM; |
| 634 | } |
| 635 | preempt_disable(); |
| 636 | jlm2->mod = __module_address((unsigned long)key); |
| 637 | preempt_enable(); |
| 638 | jlm2->entries = static_key_entries(key); |
| 639 | jlm2->next = NULL; |
| 640 | static_key_set_mod(key, jlm2); |
| 641 | static_key_set_linked(key); |
| 642 | } |
| 643 | jlm->mod = mod; |
| 644 | jlm->entries = iter; |
| 645 | jlm->next = static_key_mod(key); |
| 646 | static_key_set_mod(key, jlm); |
| 647 | static_key_set_linked(key); |
| 648 | |
| 649 | /* Only update if we've changed from our initial state */ |
| 650 | if (jump_label_type(iter) != jump_label_init_type(iter)) |
| 651 | __jump_label_update(key, iter, iter_stop, true); |
| 652 | } |
| 653 | |
| 654 | return 0; |
| 655 | } |
| 656 | |
| 657 | static void jump_label_del_module(struct module *mod) |
| 658 | { |
| 659 | struct jump_entry *iter_start = mod->jump_entries; |
| 660 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; |
| 661 | struct jump_entry *iter; |
| 662 | struct static_key *key = NULL; |
| 663 | struct static_key_mod *jlm, **prev; |
| 664 | |
| 665 | for (iter = iter_start; iter < iter_stop; iter++) { |
| 666 | if (jump_entry_key(iter) == key) |
| 667 | continue; |
| 668 | |
| 669 | key = jump_entry_key(iter); |
| 670 | |
| 671 | if (within_module((unsigned long)key, mod)) |
| 672 | continue; |
| 673 | |
| 674 | /* No memory during module load */ |
| 675 | if (WARN_ON(!static_key_linked(key))) |
| 676 | continue; |
| 677 | |
| 678 | prev = &key->next; |
| 679 | jlm = static_key_mod(key); |
| 680 | |
| 681 | while (jlm && jlm->mod != mod) { |
| 682 | prev = &jlm->next; |
| 683 | jlm = jlm->next; |
| 684 | } |
| 685 | |
| 686 | /* No memory during module load */ |
| 687 | if (WARN_ON(!jlm)) |
| 688 | continue; |
| 689 | |
| 690 | if (prev == &key->next) |
| 691 | static_key_set_mod(key, jlm->next); |
| 692 | else |
| 693 | *prev = jlm->next; |
| 694 | |
| 695 | kfree(jlm); |
| 696 | |
| 697 | jlm = static_key_mod(key); |
| 698 | /* if only one etry is left, fold it back into the static_key */ |
| 699 | if (jlm->next == NULL) { |
| 700 | static_key_set_entries(key, jlm->entries); |
| 701 | static_key_clear_linked(key); |
| 702 | kfree(jlm); |
| 703 | } |
| 704 | } |
| 705 | } |
| 706 | |
| 707 | static int |
| 708 | jump_label_module_notify(struct notifier_block *self, unsigned long val, |
| 709 | void *data) |
| 710 | { |
| 711 | struct module *mod = data; |
| 712 | int ret = 0; |
| 713 | |
| 714 | cpus_read_lock(); |
| 715 | jump_label_lock(); |
| 716 | |
| 717 | switch (val) { |
| 718 | case MODULE_STATE_COMING: |
| 719 | ret = jump_label_add_module(mod); |
| 720 | if (ret) { |
| 721 | WARN(1, "Failed to allocate memory: jump_label may not work properly.\n"); |
| 722 | jump_label_del_module(mod); |
| 723 | } |
| 724 | break; |
| 725 | case MODULE_STATE_GOING: |
| 726 | jump_label_del_module(mod); |
| 727 | break; |
| 728 | } |
| 729 | |
| 730 | jump_label_unlock(); |
| 731 | cpus_read_unlock(); |
| 732 | |
| 733 | return notifier_from_errno(ret); |
| 734 | } |
| 735 | |
| 736 | static struct notifier_block jump_label_module_nb = { |
| 737 | .notifier_call = jump_label_module_notify, |
| 738 | .priority = 1, /* higher than tracepoints */ |
| 739 | }; |
| 740 | |
| 741 | static __init int jump_label_init_module(void) |
| 742 | { |
| 743 | return register_module_notifier(&jump_label_module_nb); |
| 744 | } |
| 745 | early_initcall(jump_label_init_module); |
| 746 | |
| 747 | #endif /* CONFIG_MODULES */ |
| 748 | |
| 749 | /*** |
| 750 | * jump_label_text_reserved - check if addr range is reserved |
| 751 | * @start: start text addr |
| 752 | * @end: end text addr |
| 753 | * |
| 754 | * checks if the text addr located between @start and @end |
| 755 | * overlaps with any of the jump label patch addresses. Code |
| 756 | * that wants to modify kernel text should first verify that |
| 757 | * it does not overlap with any of the jump label addresses. |
| 758 | * Caller must hold jump_label_mutex. |
| 759 | * |
| 760 | * returns 1 if there is an overlap, 0 otherwise |
| 761 | */ |
| 762 | int jump_label_text_reserved(void *start, void *end) |
| 763 | { |
| 764 | bool init = system_state < SYSTEM_RUNNING; |
| 765 | int ret = __jump_label_text_reserved(__start___jump_table, |
| 766 | __stop___jump_table, start, end, init); |
| 767 | |
| 768 | if (ret) |
| 769 | return ret; |
| 770 | |
| 771 | #ifdef CONFIG_MODULES |
| 772 | ret = __jump_label_mod_text_reserved(start, end); |
| 773 | #endif |
| 774 | return ret; |
| 775 | } |
| 776 | |
| 777 | static void jump_label_update(struct static_key *key) |
| 778 | { |
| 779 | struct jump_entry *stop = __stop___jump_table; |
| 780 | bool init = system_state < SYSTEM_RUNNING; |
| 781 | struct jump_entry *entry; |
| 782 | #ifdef CONFIG_MODULES |
| 783 | struct module *mod; |
| 784 | |
| 785 | if (static_key_linked(key)) { |
| 786 | __jump_label_mod_update(key); |
| 787 | return; |
| 788 | } |
| 789 | |
| 790 | preempt_disable(); |
| 791 | mod = __module_address((unsigned long)key); |
| 792 | if (mod) { |
| 793 | stop = mod->jump_entries + mod->num_jump_entries; |
| 794 | init = mod->state == MODULE_STATE_COMING; |
| 795 | } |
| 796 | preempt_enable(); |
| 797 | #endif |
| 798 | entry = static_key_entries(key); |
| 799 | /* if there are no users, entry can be NULL */ |
| 800 | if (entry) |
| 801 | __jump_label_update(key, entry, stop, init); |
| 802 | } |
| 803 | |
| 804 | #ifdef CONFIG_STATIC_KEYS_SELFTEST |
| 805 | static DEFINE_STATIC_KEY_TRUE(sk_true); |
| 806 | static DEFINE_STATIC_KEY_FALSE(sk_false); |
| 807 | |
| 808 | static __init int jump_label_test(void) |
| 809 | { |
| 810 | int i; |
| 811 | |
| 812 | for (i = 0; i < 2; i++) { |
| 813 | WARN_ON(static_key_enabled(&sk_true.key) != true); |
| 814 | WARN_ON(static_key_enabled(&sk_false.key) != false); |
| 815 | |
| 816 | WARN_ON(!static_branch_likely(&sk_true)); |
| 817 | WARN_ON(!static_branch_unlikely(&sk_true)); |
| 818 | WARN_ON(static_branch_likely(&sk_false)); |
| 819 | WARN_ON(static_branch_unlikely(&sk_false)); |
| 820 | |
| 821 | static_branch_disable(&sk_true); |
| 822 | static_branch_enable(&sk_false); |
| 823 | |
| 824 | WARN_ON(static_key_enabled(&sk_true.key) == true); |
| 825 | WARN_ON(static_key_enabled(&sk_false.key) == false); |
| 826 | |
| 827 | WARN_ON(static_branch_likely(&sk_true)); |
| 828 | WARN_ON(static_branch_unlikely(&sk_true)); |
| 829 | WARN_ON(!static_branch_likely(&sk_false)); |
| 830 | WARN_ON(!static_branch_unlikely(&sk_false)); |
| 831 | |
| 832 | static_branch_enable(&sk_true); |
| 833 | static_branch_disable(&sk_false); |
| 834 | } |
| 835 | |
| 836 | return 0; |
| 837 | } |
| 838 | early_initcall(jump_label_test); |
| 839 | #endif /* STATIC_KEYS_SELFTEST */ |