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 SEQ_START_TOKEN; 109 110 if (*pos - 1 < nr_lock_chains) 111 return lock_chains + (*pos - 1); 112 113 return NULL; 114 } 115 116 static void *lc_next(struct seq_file *m, void *v, loff_t *pos) 117 { 118 (*pos)++; 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 struct lock_class *class; 204 unsigned long nr_unused = 0, nr_uncategorized = 0, 205 nr_irq_safe = 0, nr_irq_unsafe = 0, 206 nr_softirq_safe = 0, nr_softirq_unsafe = 0, 207 nr_hardirq_safe = 0, nr_hardirq_unsafe = 0, 208 nr_irq_read_safe = 0, nr_irq_read_unsafe = 0, 209 nr_softirq_read_safe = 0, nr_softirq_read_unsafe = 0, 210 nr_hardirq_read_safe = 0, nr_hardirq_read_unsafe = 0, 211 sum_forward_deps = 0; 212 213 list_for_each_entry(class, &all_lock_classes, lock_entry) { 214 215 if (class->usage_mask == 0) 216 nr_unused++; 217 if (class->usage_mask == LOCKF_USED) 218 nr_uncategorized++; 219 if (class->usage_mask & LOCKF_USED_IN_IRQ) 220 nr_irq_safe++; 221 if (class->usage_mask & LOCKF_ENABLED_IRQ) 222 nr_irq_unsafe++; 223 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ) 224 nr_softirq_safe++; 225 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ) 226 nr_softirq_unsafe++; 227 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ) 228 nr_hardirq_safe++; 229 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ) 230 nr_hardirq_unsafe++; 231 if (class->usage_mask & LOCKF_USED_IN_IRQ_READ) 232 nr_irq_read_safe++; 233 if (class->usage_mask & LOCKF_ENABLED_IRQ_READ) 234 nr_irq_read_unsafe++; 235 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) 236 nr_softirq_read_safe++; 237 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ) 238 nr_softirq_read_unsafe++; 239 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) 240 nr_hardirq_read_safe++; 241 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ) 242 nr_hardirq_read_unsafe++; 243 244 #ifdef CONFIG_PROVE_LOCKING 245 sum_forward_deps += lockdep_count_forward_deps(class); 246 #endif 247 } 248 #ifdef CONFIG_DEBUG_LOCKDEP 249 DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks) != nr_unused); 250 #endif 251 seq_printf(m, " lock-classes: %11lu [max: %lu]\n", 252 nr_lock_classes, MAX_LOCKDEP_KEYS); 253 seq_printf(m, " direct dependencies: %11lu [max: %lu]\n", 254 nr_list_entries, MAX_LOCKDEP_ENTRIES); 255 seq_printf(m, " indirect dependencies: %11lu\n", 256 sum_forward_deps); 257 258 /* 259 * Total number of dependencies: 260 * 261 * All irq-safe locks may nest inside irq-unsafe locks, 262 * plus all the other known dependencies: 263 */ 264 seq_printf(m, " all direct dependencies: %11lu\n", 265 nr_irq_unsafe * nr_irq_safe + 266 nr_hardirq_unsafe * nr_hardirq_safe + 267 nr_list_entries); 268 269 #ifdef CONFIG_PROVE_LOCKING 270 seq_printf(m, " dependency chains: %11lu [max: %lu]\n", 271 nr_lock_chains, MAX_LOCKDEP_CHAINS); 272 seq_printf(m, " dependency chain hlocks: %11d [max: %lu]\n", 273 nr_chain_hlocks, MAX_LOCKDEP_CHAIN_HLOCKS); 274 #endif 275 276 #ifdef CONFIG_TRACE_IRQFLAGS 277 seq_printf(m, " in-hardirq chains: %11u\n", 278 nr_hardirq_chains); 279 seq_printf(m, " in-softirq chains: %11u\n", 280 nr_softirq_chains); 281 #endif 282 seq_printf(m, " in-process chains: %11u\n", 283 nr_process_chains); 284 seq_printf(m, " stack-trace entries: %11lu [max: %lu]\n", 285 nr_stack_trace_entries, MAX_STACK_TRACE_ENTRIES); 286 seq_printf(m, " combined max dependencies: %11u\n", 287 (nr_hardirq_chains + 1) * 288 (nr_softirq_chains + 1) * 289 (nr_process_chains + 1) 290 ); 291 seq_printf(m, " hardirq-safe locks: %11lu\n", 292 nr_hardirq_safe); 293 seq_printf(m, " hardirq-unsafe locks: %11lu\n", 294 nr_hardirq_unsafe); 295 seq_printf(m, " softirq-safe locks: %11lu\n", 296 nr_softirq_safe); 297 seq_printf(m, " softirq-unsafe locks: %11lu\n", 298 nr_softirq_unsafe); 299 seq_printf(m, " irq-safe locks: %11lu\n", 300 nr_irq_safe); 301 seq_printf(m, " irq-unsafe locks: %11lu\n", 302 nr_irq_unsafe); 303 304 seq_printf(m, " hardirq-read-safe locks: %11lu\n", 305 nr_hardirq_read_safe); 306 seq_printf(m, " hardirq-read-unsafe locks: %11lu\n", 307 nr_hardirq_read_unsafe); 308 seq_printf(m, " softirq-read-safe locks: %11lu\n", 309 nr_softirq_read_safe); 310 seq_printf(m, " softirq-read-unsafe locks: %11lu\n", 311 nr_softirq_read_unsafe); 312 seq_printf(m, " irq-read-safe locks: %11lu\n", 313 nr_irq_read_safe); 314 seq_printf(m, " irq-read-unsafe locks: %11lu\n", 315 nr_irq_read_unsafe); 316 317 seq_printf(m, " uncategorized locks: %11lu\n", 318 nr_uncategorized); 319 seq_printf(m, " unused locks: %11lu\n", 320 nr_unused); 321 seq_printf(m, " max locking depth: %11u\n", 322 max_lockdep_depth); 323 #ifdef CONFIG_PROVE_LOCKING 324 seq_printf(m, " max bfs queue depth: %11u\n", 325 max_bfs_queue_depth); 326 #endif 327 lockdep_stats_debug_show(m); 328 seq_printf(m, " debug_locks: %11u\n", 329 debug_locks); 330 331 return 0; 332 } 333 334 #ifdef CONFIG_LOCK_STAT 335 336 struct lock_stat_data { 337 struct lock_class *class; 338 struct lock_class_stats stats; 339 }; 340 341 struct lock_stat_seq { 342 struct lock_stat_data *iter_end; 343 struct lock_stat_data stats[MAX_LOCKDEP_KEYS]; 344 }; 345 346 /* 347 * sort on absolute number of contentions 348 */ 349 static int lock_stat_cmp(const void *l, const void *r) 350 { 351 const struct lock_stat_data *dl = l, *dr = r; 352 unsigned long nl, nr; 353 354 nl = dl->stats.read_waittime.nr + dl->stats.write_waittime.nr; 355 nr = dr->stats.read_waittime.nr + dr->stats.write_waittime.nr; 356 357 return nr - nl; 358 } 359 360 static void seq_line(struct seq_file *m, char c, int offset, int length) 361 { 362 int i; 363 364 for (i = 0; i < offset; i++) 365 seq_puts(m, " "); 366 for (i = 0; i < length; i++) 367 seq_printf(m, "%c", c); 368 seq_puts(m, "\n"); 369 } 370 371 static void snprint_time(char *buf, size_t bufsiz, s64 nr) 372 { 373 s64 div; 374 s32 rem; 375 376 nr += 5; /* for display rounding */ 377 div = div_s64_rem(nr, 1000, &rem); 378 snprintf(buf, bufsiz, "%lld.%02d", (long long)div, (int)rem/10); 379 } 380 381 static void seq_time(struct seq_file *m, s64 time) 382 { 383 char num[15]; 384 385 snprint_time(num, sizeof(num), time); 386 seq_printf(m, " %14s", num); 387 } 388 389 static void seq_lock_time(struct seq_file *m, struct lock_time *lt) 390 { 391 seq_printf(m, "%14lu", lt->nr); 392 seq_time(m, lt->min); 393 seq_time(m, lt->max); 394 seq_time(m, lt->total); 395 seq_time(m, lt->nr ? div_s64(lt->total, lt->nr) : 0); 396 } 397 398 static void seq_stats(struct seq_file *m, struct lock_stat_data *data) 399 { 400 struct lockdep_subclass_key *ckey; 401 struct lock_class_stats *stats; 402 struct lock_class *class; 403 const char *cname; 404 int i, namelen; 405 char name[39]; 406 407 class = data->class; 408 stats = &data->stats; 409 410 namelen = 38; 411 if (class->name_version > 1) 412 namelen -= 2; /* XXX truncates versions > 9 */ 413 if (class->subclass) 414 namelen -= 2; 415 416 rcu_read_lock_sched(); 417 cname = rcu_dereference_sched(class->name); 418 ckey = rcu_dereference_sched(class->key); 419 420 if (!cname && !ckey) { 421 rcu_read_unlock_sched(); 422 return; 423 424 } else if (!cname) { 425 char str[KSYM_NAME_LEN]; 426 const char *key_name; 427 428 key_name = __get_key_name(ckey, str); 429 snprintf(name, namelen, "%s", key_name); 430 } else { 431 snprintf(name, namelen, "%s", cname); 432 } 433 rcu_read_unlock_sched(); 434 435 namelen = strlen(name); 436 if (class->name_version > 1) { 437 snprintf(name+namelen, 3, "#%d", class->name_version); 438 namelen += 2; 439 } 440 if (class->subclass) { 441 snprintf(name+namelen, 3, "/%d", class->subclass); 442 namelen += 2; 443 } 444 445 if (stats->write_holdtime.nr) { 446 if (stats->read_holdtime.nr) 447 seq_printf(m, "%38s-W:", name); 448 else 449 seq_printf(m, "%40s:", name); 450 451 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]); 452 seq_lock_time(m, &stats->write_waittime); 453 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]); 454 seq_lock_time(m, &stats->write_holdtime); 455 seq_puts(m, "\n"); 456 } 457 458 if (stats->read_holdtime.nr) { 459 seq_printf(m, "%38s-R:", name); 460 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]); 461 seq_lock_time(m, &stats->read_waittime); 462 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]); 463 seq_lock_time(m, &stats->read_holdtime); 464 seq_puts(m, "\n"); 465 } 466 467 if (stats->read_waittime.nr + stats->write_waittime.nr == 0) 468 return; 469 470 if (stats->read_holdtime.nr) 471 namelen += 2; 472 473 for (i = 0; i < LOCKSTAT_POINTS; i++) { 474 char ip[32]; 475 476 if (class->contention_point[i] == 0) 477 break; 478 479 if (!i) 480 seq_line(m, '-', 40-namelen, namelen); 481 482 snprintf(ip, sizeof(ip), "[<%p>]", 483 (void *)class->contention_point[i]); 484 seq_printf(m, "%40s %14lu %29s %pS\n", 485 name, stats->contention_point[i], 486 ip, (void *)class->contention_point[i]); 487 } 488 for (i = 0; i < LOCKSTAT_POINTS; i++) { 489 char ip[32]; 490 491 if (class->contending_point[i] == 0) 492 break; 493 494 if (!i) 495 seq_line(m, '-', 40-namelen, namelen); 496 497 snprintf(ip, sizeof(ip), "[<%p>]", 498 (void *)class->contending_point[i]); 499 seq_printf(m, "%40s %14lu %29s %pS\n", 500 name, stats->contending_point[i], 501 ip, (void *)class->contending_point[i]); 502 } 503 if (i) { 504 seq_puts(m, "\n"); 505 seq_line(m, '.', 0, 40 + 1 + 12 * (14 + 1)); 506 seq_puts(m, "\n"); 507 } 508 } 509 510 static void seq_header(struct seq_file *m) 511 { 512 seq_puts(m, "lock_stat version 0.4\n"); 513 514 if (unlikely(!debug_locks)) 515 seq_printf(m, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n"); 516 517 seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1)); 518 seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s %14s %14s " 519 "%14s %14s\n", 520 "class name", 521 "con-bounces", 522 "contentions", 523 "waittime-min", 524 "waittime-max", 525 "waittime-total", 526 "waittime-avg", 527 "acq-bounces", 528 "acquisitions", 529 "holdtime-min", 530 "holdtime-max", 531 "holdtime-total", 532 "holdtime-avg"); 533 seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1)); 534 seq_printf(m, "\n"); 535 } 536 537 static void *ls_start(struct seq_file *m, loff_t *pos) 538 { 539 struct lock_stat_seq *data = m->private; 540 struct lock_stat_data *iter; 541 542 if (*pos == 0) 543 return SEQ_START_TOKEN; 544 545 iter = data->stats + (*pos - 1); 546 if (iter >= data->iter_end) 547 iter = NULL; 548 549 return iter; 550 } 551 552 static void *ls_next(struct seq_file *m, void *v, loff_t *pos) 553 { 554 (*pos)++; 555 return ls_start(m, pos); 556 } 557 558 static void ls_stop(struct seq_file *m, void *v) 559 { 560 } 561 562 static int ls_show(struct seq_file *m, void *v) 563 { 564 if (v == SEQ_START_TOKEN) 565 seq_header(m); 566 else 567 seq_stats(m, v); 568 569 return 0; 570 } 571 572 static const struct seq_operations lockstat_ops = { 573 .start = ls_start, 574 .next = ls_next, 575 .stop = ls_stop, 576 .show = ls_show, 577 }; 578 579 static int lock_stat_open(struct inode *inode, struct file *file) 580 { 581 int res; 582 struct lock_class *class; 583 struct lock_stat_seq *data = vmalloc(sizeof(struct lock_stat_seq)); 584 585 if (!data) 586 return -ENOMEM; 587 588 res = seq_open(file, &lockstat_ops); 589 if (!res) { 590 struct lock_stat_data *iter = data->stats; 591 struct seq_file *m = file->private_data; 592 593 list_for_each_entry(class, &all_lock_classes, lock_entry) { 594 iter->class = class; 595 iter->stats = lock_stats(class); 596 iter++; 597 } 598 data->iter_end = iter; 599 600 sort(data->stats, data->iter_end - data->stats, 601 sizeof(struct lock_stat_data), 602 lock_stat_cmp, NULL); 603 604 m->private = data; 605 } else 606 vfree(data); 607 608 return res; 609 } 610 611 static ssize_t lock_stat_write(struct file *file, const char __user *buf, 612 size_t count, loff_t *ppos) 613 { 614 struct lock_class *class; 615 char c; 616 617 if (count) { 618 if (get_user(c, buf)) 619 return -EFAULT; 620 621 if (c != '0') 622 return count; 623 624 list_for_each_entry(class, &all_lock_classes, lock_entry) 625 clear_lock_stats(class); 626 } 627 return count; 628 } 629 630 static int lock_stat_release(struct inode *inode, struct file *file) 631 { 632 struct seq_file *seq = file->private_data; 633 634 vfree(seq->private); 635 return seq_release(inode, file); 636 } 637 638 static const struct file_operations proc_lock_stat_operations = { 639 .open = lock_stat_open, 640 .write = lock_stat_write, 641 .read = seq_read, 642 .llseek = seq_lseek, 643 .release = lock_stat_release, 644 }; 645 #endif /* CONFIG_LOCK_STAT */ 646 647 static int __init lockdep_proc_init(void) 648 { 649 proc_create_seq("lockdep", S_IRUSR, NULL, &lockdep_ops); 650 #ifdef CONFIG_PROVE_LOCKING 651 proc_create_seq("lockdep_chains", S_IRUSR, NULL, &lockdep_chains_ops); 652 #endif 653 proc_create_single("lockdep_stats", S_IRUSR, NULL, lockdep_stats_show); 654 #ifdef CONFIG_LOCK_STAT 655 proc_create("lock_stat", S_IRUSR | S_IWUSR, NULL, 656 &proc_lock_stat_operations); 657 #endif 658 659 return 0; 660 } 661 662 __initcall(lockdep_proc_init); 663 664