1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * kernel/lockdep_proc.c 4 * 5 * Runtime locking correctness validator 6 * 7 * Started by Ingo Molnar: 8 * 9 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> 10 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra 11 * 12 * Code for /proc/lockdep and /proc/lockdep_stats: 13 * 14 */ 15 #include <linux/export.h> 16 #include <linux/proc_fs.h> 17 #include <linux/seq_file.h> 18 #include <linux/kallsyms.h> 19 #include <linux/debug_locks.h> 20 #include <linux/vmalloc.h> 21 #include <linux/sort.h> 22 #include <linux/uaccess.h> 23 #include <asm/div64.h> 24 25 #include "lockdep_internals.h" 26 27 static void *l_next(struct seq_file *m, void *v, loff_t *pos) 28 { 29 return seq_list_next(v, &all_lock_classes, pos); 30 } 31 32 static void *l_start(struct seq_file *m, loff_t *pos) 33 { 34 return seq_list_start_head(&all_lock_classes, *pos); 35 } 36 37 static void l_stop(struct seq_file *m, void *v) 38 { 39 } 40 41 static void print_name(struct seq_file *m, struct lock_class *class) 42 { 43 char str[KSYM_NAME_LEN]; 44 const char *name = class->name; 45 46 if (!name) { 47 name = __get_key_name(class->key, str); 48 seq_printf(m, "%s", name); 49 } else{ 50 seq_printf(m, "%s", name); 51 if (class->name_version > 1) 52 seq_printf(m, "#%d", class->name_version); 53 if (class->subclass) 54 seq_printf(m, "/%d", class->subclass); 55 } 56 } 57 58 static int l_show(struct seq_file *m, void *v) 59 { 60 struct lock_class *class = list_entry(v, struct lock_class, lock_entry); 61 struct lock_list *entry; 62 char usage[LOCK_USAGE_CHARS]; 63 64 if (v == &all_lock_classes) { 65 seq_printf(m, "all lock classes:\n"); 66 return 0; 67 } 68 69 seq_printf(m, "%p", class->key); 70 #ifdef CONFIG_DEBUG_LOCKDEP 71 seq_printf(m, " OPS:%8ld", debug_class_ops_read(class)); 72 #endif 73 #ifdef CONFIG_PROVE_LOCKING 74 seq_printf(m, " FD:%5ld", lockdep_count_forward_deps(class)); 75 seq_printf(m, " BD:%5ld", lockdep_count_backward_deps(class)); 76 #endif 77 78 get_usage_chars(class, usage); 79 seq_printf(m, " %s", usage); 80 81 seq_printf(m, ": "); 82 print_name(m, class); 83 seq_puts(m, "\n"); 84 85 list_for_each_entry(entry, &class->locks_after, entry) { 86 if (entry->distance == 1) { 87 seq_printf(m, " -> [%p] ", entry->class->key); 88 print_name(m, entry->class); 89 seq_puts(m, "\n"); 90 } 91 } 92 seq_puts(m, "\n"); 93 94 return 0; 95 } 96 97 static const struct seq_operations lockdep_ops = { 98 .start = l_start, 99 .next = l_next, 100 .stop = l_stop, 101 .show = l_show, 102 }; 103 104 #ifdef CONFIG_PROVE_LOCKING 105 static void *lc_start(struct seq_file *m, loff_t *pos) 106 { 107 if (*pos < 0) 108 return NULL; 109 110 if (*pos == 0) 111 return SEQ_START_TOKEN; 112 113 return lock_chains + (*pos - 1); 114 } 115 116 static void *lc_next(struct seq_file *m, void *v, loff_t *pos) 117 { 118 *pos = lockdep_next_lockchain(*pos - 1) + 1; 119 return lc_start(m, pos); 120 } 121 122 static void lc_stop(struct seq_file *m, void *v) 123 { 124 } 125 126 static int lc_show(struct seq_file *m, void *v) 127 { 128 struct lock_chain *chain = v; 129 struct lock_class *class; 130 int i; 131 132 if (v == SEQ_START_TOKEN) { 133 if (nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS) 134 seq_printf(m, "(buggered) "); 135 seq_printf(m, "all lock chains:\n"); 136 return 0; 137 } 138 139 seq_printf(m, "irq_context: %d\n", chain->irq_context); 140 141 for (i = 0; i < chain->depth; i++) { 142 class = lock_chain_get_class(chain, i); 143 if (!class->key) 144 continue; 145 146 seq_printf(m, "[%p] ", class->key); 147 print_name(m, class); 148 seq_puts(m, "\n"); 149 } 150 seq_puts(m, "\n"); 151 152 return 0; 153 } 154 155 static const struct seq_operations lockdep_chains_ops = { 156 .start = lc_start, 157 .next = lc_next, 158 .stop = lc_stop, 159 .show = lc_show, 160 }; 161 #endif /* CONFIG_PROVE_LOCKING */ 162 163 static void lockdep_stats_debug_show(struct seq_file *m) 164 { 165 #ifdef CONFIG_DEBUG_LOCKDEP 166 unsigned long long hi1 = debug_atomic_read(hardirqs_on_events), 167 hi2 = debug_atomic_read(hardirqs_off_events), 168 hr1 = debug_atomic_read(redundant_hardirqs_on), 169 hr2 = debug_atomic_read(redundant_hardirqs_off), 170 si1 = debug_atomic_read(softirqs_on_events), 171 si2 = debug_atomic_read(softirqs_off_events), 172 sr1 = debug_atomic_read(redundant_softirqs_on), 173 sr2 = debug_atomic_read(redundant_softirqs_off); 174 175 seq_printf(m, " chain lookup misses: %11llu\n", 176 debug_atomic_read(chain_lookup_misses)); 177 seq_printf(m, " chain lookup hits: %11llu\n", 178 debug_atomic_read(chain_lookup_hits)); 179 seq_printf(m, " cyclic checks: %11llu\n", 180 debug_atomic_read(nr_cyclic_checks)); 181 seq_printf(m, " redundant checks: %11llu\n", 182 debug_atomic_read(nr_redundant_checks)); 183 seq_printf(m, " redundant links: %11llu\n", 184 debug_atomic_read(nr_redundant)); 185 seq_printf(m, " find-mask forwards checks: %11llu\n", 186 debug_atomic_read(nr_find_usage_forwards_checks)); 187 seq_printf(m, " find-mask backwards checks: %11llu\n", 188 debug_atomic_read(nr_find_usage_backwards_checks)); 189 190 seq_printf(m, " hardirq on events: %11llu\n", hi1); 191 seq_printf(m, " hardirq off events: %11llu\n", hi2); 192 seq_printf(m, " redundant hardirq ons: %11llu\n", hr1); 193 seq_printf(m, " redundant hardirq offs: %11llu\n", hr2); 194 seq_printf(m, " softirq on events: %11llu\n", si1); 195 seq_printf(m, " softirq off events: %11llu\n", si2); 196 seq_printf(m, " redundant softirq ons: %11llu\n", sr1); 197 seq_printf(m, " redundant softirq offs: %11llu\n", sr2); 198 #endif 199 } 200 201 static int lockdep_stats_show(struct seq_file *m, void *v) 202 { 203 unsigned long nr_unused = 0, nr_uncategorized = 0, 204 nr_irq_safe = 0, nr_irq_unsafe = 0, 205 nr_softirq_safe = 0, nr_softirq_unsafe = 0, 206 nr_hardirq_safe = 0, nr_hardirq_unsafe = 0, 207 nr_irq_read_safe = 0, nr_irq_read_unsafe = 0, 208 nr_softirq_read_safe = 0, nr_softirq_read_unsafe = 0, 209 nr_hardirq_read_safe = 0, nr_hardirq_read_unsafe = 0, 210 sum_forward_deps = 0; 211 212 #ifdef CONFIG_PROVE_LOCKING 213 struct lock_class *class; 214 215 list_for_each_entry(class, &all_lock_classes, lock_entry) { 216 217 if (class->usage_mask == 0) 218 nr_unused++; 219 if (class->usage_mask == LOCKF_USED) 220 nr_uncategorized++; 221 if (class->usage_mask & LOCKF_USED_IN_IRQ) 222 nr_irq_safe++; 223 if (class->usage_mask & LOCKF_ENABLED_IRQ) 224 nr_irq_unsafe++; 225 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ) 226 nr_softirq_safe++; 227 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ) 228 nr_softirq_unsafe++; 229 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ) 230 nr_hardirq_safe++; 231 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ) 232 nr_hardirq_unsafe++; 233 if (class->usage_mask & LOCKF_USED_IN_IRQ_READ) 234 nr_irq_read_safe++; 235 if (class->usage_mask & LOCKF_ENABLED_IRQ_READ) 236 nr_irq_read_unsafe++; 237 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) 238 nr_softirq_read_safe++; 239 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ) 240 nr_softirq_read_unsafe++; 241 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) 242 nr_hardirq_read_safe++; 243 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ) 244 nr_hardirq_read_unsafe++; 245 246 sum_forward_deps += lockdep_count_forward_deps(class); 247 } 248 #ifdef CONFIG_DEBUG_LOCKDEP 249 DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks) != nr_unused); 250 #endif 251 252 #endif 253 seq_printf(m, " lock-classes: %11lu [max: %lu]\n", 254 nr_lock_classes, MAX_LOCKDEP_KEYS); 255 seq_printf(m, " direct dependencies: %11lu [max: %lu]\n", 256 nr_list_entries, MAX_LOCKDEP_ENTRIES); 257 seq_printf(m, " indirect dependencies: %11lu\n", 258 sum_forward_deps); 259 260 /* 261 * Total number of dependencies: 262 * 263 * All irq-safe locks may nest inside irq-unsafe locks, 264 * plus all the other known dependencies: 265 */ 266 seq_printf(m, " all direct dependencies: %11lu\n", 267 nr_irq_unsafe * nr_irq_safe + 268 nr_hardirq_unsafe * nr_hardirq_safe + 269 nr_list_entries); 270 271 #ifdef CONFIG_PROVE_LOCKING 272 seq_printf(m, " dependency chains: %11lu [max: %lu]\n", 273 lock_chain_count(), MAX_LOCKDEP_CHAINS); 274 seq_printf(m, " dependency chain hlocks: %11d [max: %lu]\n", 275 nr_chain_hlocks, MAX_LOCKDEP_CHAIN_HLOCKS); 276 #endif 277 278 #ifdef CONFIG_TRACE_IRQFLAGS 279 seq_printf(m, " in-hardirq chains: %11u\n", 280 nr_hardirq_chains); 281 seq_printf(m, " in-softirq chains: %11u\n", 282 nr_softirq_chains); 283 #endif 284 seq_printf(m, " in-process chains: %11u\n", 285 nr_process_chains); 286 seq_printf(m, " stack-trace entries: %11lu [max: %lu]\n", 287 nr_stack_trace_entries, MAX_STACK_TRACE_ENTRIES); 288 seq_printf(m, " combined max dependencies: %11u\n", 289 (nr_hardirq_chains + 1) * 290 (nr_softirq_chains + 1) * 291 (nr_process_chains + 1) 292 ); 293 seq_printf(m, " hardirq-safe locks: %11lu\n", 294 nr_hardirq_safe); 295 seq_printf(m, " hardirq-unsafe locks: %11lu\n", 296 nr_hardirq_unsafe); 297 seq_printf(m, " softirq-safe locks: %11lu\n", 298 nr_softirq_safe); 299 seq_printf(m, " softirq-unsafe locks: %11lu\n", 300 nr_softirq_unsafe); 301 seq_printf(m, " irq-safe locks: %11lu\n", 302 nr_irq_safe); 303 seq_printf(m, " irq-unsafe locks: %11lu\n", 304 nr_irq_unsafe); 305 306 seq_printf(m, " hardirq-read-safe locks: %11lu\n", 307 nr_hardirq_read_safe); 308 seq_printf(m, " hardirq-read-unsafe locks: %11lu\n", 309 nr_hardirq_read_unsafe); 310 seq_printf(m, " softirq-read-safe locks: %11lu\n", 311 nr_softirq_read_safe); 312 seq_printf(m, " softirq-read-unsafe locks: %11lu\n", 313 nr_softirq_read_unsafe); 314 seq_printf(m, " irq-read-safe locks: %11lu\n", 315 nr_irq_read_safe); 316 seq_printf(m, " irq-read-unsafe locks: %11lu\n", 317 nr_irq_read_unsafe); 318 319 seq_printf(m, " uncategorized locks: %11lu\n", 320 nr_uncategorized); 321 seq_printf(m, " unused locks: %11lu\n", 322 nr_unused); 323 seq_printf(m, " max locking depth: %11u\n", 324 max_lockdep_depth); 325 #ifdef CONFIG_PROVE_LOCKING 326 seq_printf(m, " max bfs queue depth: %11u\n", 327 max_bfs_queue_depth); 328 #endif 329 lockdep_stats_debug_show(m); 330 seq_printf(m, " debug_locks: %11u\n", 331 debug_locks); 332 333 return 0; 334 } 335 336 #ifdef CONFIG_LOCK_STAT 337 338 struct lock_stat_data { 339 struct lock_class *class; 340 struct lock_class_stats stats; 341 }; 342 343 struct lock_stat_seq { 344 struct lock_stat_data *iter_end; 345 struct lock_stat_data stats[MAX_LOCKDEP_KEYS]; 346 }; 347 348 /* 349 * sort on absolute number of contentions 350 */ 351 static int lock_stat_cmp(const void *l, const void *r) 352 { 353 const struct lock_stat_data *dl = l, *dr = r; 354 unsigned long nl, nr; 355 356 nl = dl->stats.read_waittime.nr + dl->stats.write_waittime.nr; 357 nr = dr->stats.read_waittime.nr + dr->stats.write_waittime.nr; 358 359 return nr - nl; 360 } 361 362 static void seq_line(struct seq_file *m, char c, int offset, int length) 363 { 364 int i; 365 366 for (i = 0; i < offset; i++) 367 seq_puts(m, " "); 368 for (i = 0; i < length; i++) 369 seq_printf(m, "%c", c); 370 seq_puts(m, "\n"); 371 } 372 373 static void snprint_time(char *buf, size_t bufsiz, s64 nr) 374 { 375 s64 div; 376 s32 rem; 377 378 nr += 5; /* for display rounding */ 379 div = div_s64_rem(nr, 1000, &rem); 380 snprintf(buf, bufsiz, "%lld.%02d", (long long)div, (int)rem/10); 381 } 382 383 static void seq_time(struct seq_file *m, s64 time) 384 { 385 char num[15]; 386 387 snprint_time(num, sizeof(num), time); 388 seq_printf(m, " %14s", num); 389 } 390 391 static void seq_lock_time(struct seq_file *m, struct lock_time *lt) 392 { 393 seq_printf(m, "%14lu", lt->nr); 394 seq_time(m, lt->min); 395 seq_time(m, lt->max); 396 seq_time(m, lt->total); 397 seq_time(m, lt->nr ? div_s64(lt->total, lt->nr) : 0); 398 } 399 400 static void seq_stats(struct seq_file *m, struct lock_stat_data *data) 401 { 402 struct lockdep_subclass_key *ckey; 403 struct lock_class_stats *stats; 404 struct lock_class *class; 405 const char *cname; 406 int i, namelen; 407 char name[39]; 408 409 class = data->class; 410 stats = &data->stats; 411 412 namelen = 38; 413 if (class->name_version > 1) 414 namelen -= 2; /* XXX truncates versions > 9 */ 415 if (class->subclass) 416 namelen -= 2; 417 418 rcu_read_lock_sched(); 419 cname = rcu_dereference_sched(class->name); 420 ckey = rcu_dereference_sched(class->key); 421 422 if (!cname && !ckey) { 423 rcu_read_unlock_sched(); 424 return; 425 426 } else if (!cname) { 427 char str[KSYM_NAME_LEN]; 428 const char *key_name; 429 430 key_name = __get_key_name(ckey, str); 431 snprintf(name, namelen, "%s", key_name); 432 } else { 433 snprintf(name, namelen, "%s", cname); 434 } 435 rcu_read_unlock_sched(); 436 437 namelen = strlen(name); 438 if (class->name_version > 1) { 439 snprintf(name+namelen, 3, "#%d", class->name_version); 440 namelen += 2; 441 } 442 if (class->subclass) { 443 snprintf(name+namelen, 3, "/%d", class->subclass); 444 namelen += 2; 445 } 446 447 if (stats->write_holdtime.nr) { 448 if (stats->read_holdtime.nr) 449 seq_printf(m, "%38s-W:", name); 450 else 451 seq_printf(m, "%40s:", name); 452 453 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]); 454 seq_lock_time(m, &stats->write_waittime); 455 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]); 456 seq_lock_time(m, &stats->write_holdtime); 457 seq_puts(m, "\n"); 458 } 459 460 if (stats->read_holdtime.nr) { 461 seq_printf(m, "%38s-R:", name); 462 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]); 463 seq_lock_time(m, &stats->read_waittime); 464 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]); 465 seq_lock_time(m, &stats->read_holdtime); 466 seq_puts(m, "\n"); 467 } 468 469 if (stats->read_waittime.nr + stats->write_waittime.nr == 0) 470 return; 471 472 if (stats->read_holdtime.nr) 473 namelen += 2; 474 475 for (i = 0; i < LOCKSTAT_POINTS; i++) { 476 char ip[32]; 477 478 if (class->contention_point[i] == 0) 479 break; 480 481 if (!i) 482 seq_line(m, '-', 40-namelen, namelen); 483 484 snprintf(ip, sizeof(ip), "[<%p>]", 485 (void *)class->contention_point[i]); 486 seq_printf(m, "%40s %14lu %29s %pS\n", 487 name, stats->contention_point[i], 488 ip, (void *)class->contention_point[i]); 489 } 490 for (i = 0; i < LOCKSTAT_POINTS; i++) { 491 char ip[32]; 492 493 if (class->contending_point[i] == 0) 494 break; 495 496 if (!i) 497 seq_line(m, '-', 40-namelen, namelen); 498 499 snprintf(ip, sizeof(ip), "[<%p>]", 500 (void *)class->contending_point[i]); 501 seq_printf(m, "%40s %14lu %29s %pS\n", 502 name, stats->contending_point[i], 503 ip, (void *)class->contending_point[i]); 504 } 505 if (i) { 506 seq_puts(m, "\n"); 507 seq_line(m, '.', 0, 40 + 1 + 12 * (14 + 1)); 508 seq_puts(m, "\n"); 509 } 510 } 511 512 static void seq_header(struct seq_file *m) 513 { 514 seq_puts(m, "lock_stat version 0.4\n"); 515 516 if (unlikely(!debug_locks)) 517 seq_printf(m, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n"); 518 519 seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1)); 520 seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s %14s %14s " 521 "%14s %14s\n", 522 "class name", 523 "con-bounces", 524 "contentions", 525 "waittime-min", 526 "waittime-max", 527 "waittime-total", 528 "waittime-avg", 529 "acq-bounces", 530 "acquisitions", 531 "holdtime-min", 532 "holdtime-max", 533 "holdtime-total", 534 "holdtime-avg"); 535 seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1)); 536 seq_printf(m, "\n"); 537 } 538 539 static void *ls_start(struct seq_file *m, loff_t *pos) 540 { 541 struct lock_stat_seq *data = m->private; 542 struct lock_stat_data *iter; 543 544 if (*pos == 0) 545 return SEQ_START_TOKEN; 546 547 iter = data->stats + (*pos - 1); 548 if (iter >= data->iter_end) 549 iter = NULL; 550 551 return iter; 552 } 553 554 static void *ls_next(struct seq_file *m, void *v, loff_t *pos) 555 { 556 (*pos)++; 557 return ls_start(m, pos); 558 } 559 560 static void ls_stop(struct seq_file *m, void *v) 561 { 562 } 563 564 static int ls_show(struct seq_file *m, void *v) 565 { 566 if (v == SEQ_START_TOKEN) 567 seq_header(m); 568 else 569 seq_stats(m, v); 570 571 return 0; 572 } 573 574 static const struct seq_operations lockstat_ops = { 575 .start = ls_start, 576 .next = ls_next, 577 .stop = ls_stop, 578 .show = ls_show, 579 }; 580 581 static int lock_stat_open(struct inode *inode, struct file *file) 582 { 583 int res; 584 struct lock_class *class; 585 struct lock_stat_seq *data = vmalloc(sizeof(struct lock_stat_seq)); 586 587 if (!data) 588 return -ENOMEM; 589 590 res = seq_open(file, &lockstat_ops); 591 if (!res) { 592 struct lock_stat_data *iter = data->stats; 593 struct seq_file *m = file->private_data; 594 595 list_for_each_entry(class, &all_lock_classes, lock_entry) { 596 iter->class = class; 597 iter->stats = lock_stats(class); 598 iter++; 599 } 600 data->iter_end = iter; 601 602 sort(data->stats, data->iter_end - data->stats, 603 sizeof(struct lock_stat_data), 604 lock_stat_cmp, NULL); 605 606 m->private = data; 607 } else 608 vfree(data); 609 610 return res; 611 } 612 613 static ssize_t lock_stat_write(struct file *file, const char __user *buf, 614 size_t count, loff_t *ppos) 615 { 616 struct lock_class *class; 617 char c; 618 619 if (count) { 620 if (get_user(c, buf)) 621 return -EFAULT; 622 623 if (c != '0') 624 return count; 625 626 list_for_each_entry(class, &all_lock_classes, lock_entry) 627 clear_lock_stats(class); 628 } 629 return count; 630 } 631 632 static int lock_stat_release(struct inode *inode, struct file *file) 633 { 634 struct seq_file *seq = file->private_data; 635 636 vfree(seq->private); 637 return seq_release(inode, file); 638 } 639 640 static const struct file_operations proc_lock_stat_operations = { 641 .open = lock_stat_open, 642 .write = lock_stat_write, 643 .read = seq_read, 644 .llseek = seq_lseek, 645 .release = lock_stat_release, 646 }; 647 #endif /* CONFIG_LOCK_STAT */ 648 649 static int __init lockdep_proc_init(void) 650 { 651 proc_create_seq("lockdep", S_IRUSR, NULL, &lockdep_ops); 652 #ifdef CONFIG_PROVE_LOCKING 653 proc_create_seq("lockdep_chains", S_IRUSR, NULL, &lockdep_chains_ops); 654 #endif 655 proc_create_single("lockdep_stats", S_IRUSR, NULL, lockdep_stats_show); 656 #ifdef CONFIG_LOCK_STAT 657 proc_create("lock_stat", S_IRUSR | S_IWUSR, NULL, 658 &proc_lock_stat_operations); 659 #endif 660 661 return 0; 662 } 663 664 __initcall(lockdep_proc_init); 665 666