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 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) 289 seq_printf(m, " number of stack traces: %llu\n", 290 lockdep_stack_trace_count()); 291 seq_printf(m, " number of stack hash chains: %llu\n", 292 lockdep_stack_hash_count()); 293 #endif 294 seq_printf(m, " combined max dependencies: %11u\n", 295 (nr_hardirq_chains + 1) * 296 (nr_softirq_chains + 1) * 297 (nr_process_chains + 1) 298 ); 299 seq_printf(m, " hardirq-safe locks: %11lu\n", 300 nr_hardirq_safe); 301 seq_printf(m, " hardirq-unsafe locks: %11lu\n", 302 nr_hardirq_unsafe); 303 seq_printf(m, " softirq-safe locks: %11lu\n", 304 nr_softirq_safe); 305 seq_printf(m, " softirq-unsafe locks: %11lu\n", 306 nr_softirq_unsafe); 307 seq_printf(m, " irq-safe locks: %11lu\n", 308 nr_irq_safe); 309 seq_printf(m, " irq-unsafe locks: %11lu\n", 310 nr_irq_unsafe); 311 312 seq_printf(m, " hardirq-read-safe locks: %11lu\n", 313 nr_hardirq_read_safe); 314 seq_printf(m, " hardirq-read-unsafe locks: %11lu\n", 315 nr_hardirq_read_unsafe); 316 seq_printf(m, " softirq-read-safe locks: %11lu\n", 317 nr_softirq_read_safe); 318 seq_printf(m, " softirq-read-unsafe locks: %11lu\n", 319 nr_softirq_read_unsafe); 320 seq_printf(m, " irq-read-safe locks: %11lu\n", 321 nr_irq_read_safe); 322 seq_printf(m, " irq-read-unsafe locks: %11lu\n", 323 nr_irq_read_unsafe); 324 325 seq_printf(m, " uncategorized locks: %11lu\n", 326 nr_uncategorized); 327 seq_printf(m, " unused locks: %11lu\n", 328 nr_unused); 329 seq_printf(m, " max locking depth: %11u\n", 330 max_lockdep_depth); 331 #ifdef CONFIG_PROVE_LOCKING 332 seq_printf(m, " max bfs queue depth: %11u\n", 333 max_bfs_queue_depth); 334 #endif 335 lockdep_stats_debug_show(m); 336 seq_printf(m, " debug_locks: %11u\n", 337 debug_locks); 338 339 return 0; 340 } 341 342 #ifdef CONFIG_LOCK_STAT 343 344 struct lock_stat_data { 345 struct lock_class *class; 346 struct lock_class_stats stats; 347 }; 348 349 struct lock_stat_seq { 350 struct lock_stat_data *iter_end; 351 struct lock_stat_data stats[MAX_LOCKDEP_KEYS]; 352 }; 353 354 /* 355 * sort on absolute number of contentions 356 */ 357 static int lock_stat_cmp(const void *l, const void *r) 358 { 359 const struct lock_stat_data *dl = l, *dr = r; 360 unsigned long nl, nr; 361 362 nl = dl->stats.read_waittime.nr + dl->stats.write_waittime.nr; 363 nr = dr->stats.read_waittime.nr + dr->stats.write_waittime.nr; 364 365 return nr - nl; 366 } 367 368 static void seq_line(struct seq_file *m, char c, int offset, int length) 369 { 370 int i; 371 372 for (i = 0; i < offset; i++) 373 seq_puts(m, " "); 374 for (i = 0; i < length; i++) 375 seq_printf(m, "%c", c); 376 seq_puts(m, "\n"); 377 } 378 379 static void snprint_time(char *buf, size_t bufsiz, s64 nr) 380 { 381 s64 div; 382 s32 rem; 383 384 nr += 5; /* for display rounding */ 385 div = div_s64_rem(nr, 1000, &rem); 386 snprintf(buf, bufsiz, "%lld.%02d", (long long)div, (int)rem/10); 387 } 388 389 static void seq_time(struct seq_file *m, s64 time) 390 { 391 char num[15]; 392 393 snprint_time(num, sizeof(num), time); 394 seq_printf(m, " %14s", num); 395 } 396 397 static void seq_lock_time(struct seq_file *m, struct lock_time *lt) 398 { 399 seq_printf(m, "%14lu", lt->nr); 400 seq_time(m, lt->min); 401 seq_time(m, lt->max); 402 seq_time(m, lt->total); 403 seq_time(m, lt->nr ? div_s64(lt->total, lt->nr) : 0); 404 } 405 406 static void seq_stats(struct seq_file *m, struct lock_stat_data *data) 407 { 408 const struct lockdep_subclass_key *ckey; 409 struct lock_class_stats *stats; 410 struct lock_class *class; 411 const char *cname; 412 int i, namelen; 413 char name[39]; 414 415 class = data->class; 416 stats = &data->stats; 417 418 namelen = 38; 419 if (class->name_version > 1) 420 namelen -= 2; /* XXX truncates versions > 9 */ 421 if (class->subclass) 422 namelen -= 2; 423 424 rcu_read_lock_sched(); 425 cname = rcu_dereference_sched(class->name); 426 ckey = rcu_dereference_sched(class->key); 427 428 if (!cname && !ckey) { 429 rcu_read_unlock_sched(); 430 return; 431 432 } else if (!cname) { 433 char str[KSYM_NAME_LEN]; 434 const char *key_name; 435 436 key_name = __get_key_name(ckey, str); 437 snprintf(name, namelen, "%s", key_name); 438 } else { 439 snprintf(name, namelen, "%s", cname); 440 } 441 rcu_read_unlock_sched(); 442 443 namelen = strlen(name); 444 if (class->name_version > 1) { 445 snprintf(name+namelen, 3, "#%d", class->name_version); 446 namelen += 2; 447 } 448 if (class->subclass) { 449 snprintf(name+namelen, 3, "/%d", class->subclass); 450 namelen += 2; 451 } 452 453 if (stats->write_holdtime.nr) { 454 if (stats->read_holdtime.nr) 455 seq_printf(m, "%38s-W:", name); 456 else 457 seq_printf(m, "%40s:", name); 458 459 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]); 460 seq_lock_time(m, &stats->write_waittime); 461 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]); 462 seq_lock_time(m, &stats->write_holdtime); 463 seq_puts(m, "\n"); 464 } 465 466 if (stats->read_holdtime.nr) { 467 seq_printf(m, "%38s-R:", name); 468 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]); 469 seq_lock_time(m, &stats->read_waittime); 470 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]); 471 seq_lock_time(m, &stats->read_holdtime); 472 seq_puts(m, "\n"); 473 } 474 475 if (stats->read_waittime.nr + stats->write_waittime.nr == 0) 476 return; 477 478 if (stats->read_holdtime.nr) 479 namelen += 2; 480 481 for (i = 0; i < LOCKSTAT_POINTS; i++) { 482 char ip[32]; 483 484 if (class->contention_point[i] == 0) 485 break; 486 487 if (!i) 488 seq_line(m, '-', 40-namelen, namelen); 489 490 snprintf(ip, sizeof(ip), "[<%p>]", 491 (void *)class->contention_point[i]); 492 seq_printf(m, "%40s %14lu %29s %pS\n", 493 name, stats->contention_point[i], 494 ip, (void *)class->contention_point[i]); 495 } 496 for (i = 0; i < LOCKSTAT_POINTS; i++) { 497 char ip[32]; 498 499 if (class->contending_point[i] == 0) 500 break; 501 502 if (!i) 503 seq_line(m, '-', 40-namelen, namelen); 504 505 snprintf(ip, sizeof(ip), "[<%p>]", 506 (void *)class->contending_point[i]); 507 seq_printf(m, "%40s %14lu %29s %pS\n", 508 name, stats->contending_point[i], 509 ip, (void *)class->contending_point[i]); 510 } 511 if (i) { 512 seq_puts(m, "\n"); 513 seq_line(m, '.', 0, 40 + 1 + 12 * (14 + 1)); 514 seq_puts(m, "\n"); 515 } 516 } 517 518 static void seq_header(struct seq_file *m) 519 { 520 seq_puts(m, "lock_stat version 0.4\n"); 521 522 if (unlikely(!debug_locks)) 523 seq_printf(m, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n"); 524 525 seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1)); 526 seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s %14s %14s " 527 "%14s %14s\n", 528 "class name", 529 "con-bounces", 530 "contentions", 531 "waittime-min", 532 "waittime-max", 533 "waittime-total", 534 "waittime-avg", 535 "acq-bounces", 536 "acquisitions", 537 "holdtime-min", 538 "holdtime-max", 539 "holdtime-total", 540 "holdtime-avg"); 541 seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1)); 542 seq_printf(m, "\n"); 543 } 544 545 static void *ls_start(struct seq_file *m, loff_t *pos) 546 { 547 struct lock_stat_seq *data = m->private; 548 struct lock_stat_data *iter; 549 550 if (*pos == 0) 551 return SEQ_START_TOKEN; 552 553 iter = data->stats + (*pos - 1); 554 if (iter >= data->iter_end) 555 iter = NULL; 556 557 return iter; 558 } 559 560 static void *ls_next(struct seq_file *m, void *v, loff_t *pos) 561 { 562 (*pos)++; 563 return ls_start(m, pos); 564 } 565 566 static void ls_stop(struct seq_file *m, void *v) 567 { 568 } 569 570 static int ls_show(struct seq_file *m, void *v) 571 { 572 if (v == SEQ_START_TOKEN) 573 seq_header(m); 574 else 575 seq_stats(m, v); 576 577 return 0; 578 } 579 580 static const struct seq_operations lockstat_ops = { 581 .start = ls_start, 582 .next = ls_next, 583 .stop = ls_stop, 584 .show = ls_show, 585 }; 586 587 static int lock_stat_open(struct inode *inode, struct file *file) 588 { 589 int res; 590 struct lock_class *class; 591 struct lock_stat_seq *data = vmalloc(sizeof(struct lock_stat_seq)); 592 593 if (!data) 594 return -ENOMEM; 595 596 res = seq_open(file, &lockstat_ops); 597 if (!res) { 598 struct lock_stat_data *iter = data->stats; 599 struct seq_file *m = file->private_data; 600 601 list_for_each_entry(class, &all_lock_classes, lock_entry) { 602 iter->class = class; 603 iter->stats = lock_stats(class); 604 iter++; 605 } 606 data->iter_end = iter; 607 608 sort(data->stats, data->iter_end - data->stats, 609 sizeof(struct lock_stat_data), 610 lock_stat_cmp, NULL); 611 612 m->private = data; 613 } else 614 vfree(data); 615 616 return res; 617 } 618 619 static ssize_t lock_stat_write(struct file *file, const char __user *buf, 620 size_t count, loff_t *ppos) 621 { 622 struct lock_class *class; 623 char c; 624 625 if (count) { 626 if (get_user(c, buf)) 627 return -EFAULT; 628 629 if (c != '0') 630 return count; 631 632 list_for_each_entry(class, &all_lock_classes, lock_entry) 633 clear_lock_stats(class); 634 } 635 return count; 636 } 637 638 static int lock_stat_release(struct inode *inode, struct file *file) 639 { 640 struct seq_file *seq = file->private_data; 641 642 vfree(seq->private); 643 return seq_release(inode, file); 644 } 645 646 static const struct file_operations proc_lock_stat_operations = { 647 .open = lock_stat_open, 648 .write = lock_stat_write, 649 .read = seq_read, 650 .llseek = seq_lseek, 651 .release = lock_stat_release, 652 }; 653 #endif /* CONFIG_LOCK_STAT */ 654 655 static int __init lockdep_proc_init(void) 656 { 657 proc_create_seq("lockdep", S_IRUSR, NULL, &lockdep_ops); 658 #ifdef CONFIG_PROVE_LOCKING 659 proc_create_seq("lockdep_chains", S_IRUSR, NULL, &lockdep_chains_ops); 660 #endif 661 proc_create_single("lockdep_stats", S_IRUSR, NULL, lockdep_stats_show); 662 #ifdef CONFIG_LOCK_STAT 663 proc_create("lock_stat", S_IRUSR | S_IWUSR, NULL, 664 &proc_lock_stat_operations); 665 #endif 666 667 return 0; 668 } 669 670 __initcall(lockdep_proc_init); 671 672