1 // SPDX-License-Identifier: GPL-2.0
3 * kernel/lockdep_proc.c
5 * Runtime locking correctness validator
7 * Started by Ingo Molnar:
9 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
10 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
12 * Code for /proc/lockdep and /proc/lockdep_stats:
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>
25 #include "lockdep_internals.h"
27 static void *l_next(struct seq_file *m, void *v, loff_t *pos)
29 return seq_list_next(v, &all_lock_classes, pos);
32 static void *l_start(struct seq_file *m, loff_t *pos)
34 return seq_list_start_head(&all_lock_classes, *pos);
37 static void l_stop(struct seq_file *m, void *v)
41 static void print_name(struct seq_file *m, struct lock_class *class)
43 char str[KSYM_NAME_LEN];
44 const char *name = class->name;
47 name = __get_key_name(class->key, str);
48 seq_printf(m, "%s", name);
50 seq_printf(m, "%s", name);
51 if (class->name_version > 1)
52 seq_printf(m, "#%d", class->name_version);
54 seq_printf(m, "/%d", class->subclass);
58 static int l_show(struct seq_file *m, void *v)
60 struct lock_class *class = list_entry(v, struct lock_class, lock_entry);
61 struct lock_list *entry;
62 char usage[LOCK_USAGE_CHARS];
64 if (v == &all_lock_classes) {
65 seq_printf(m, "all lock classes:\n");
69 seq_printf(m, "%p", class->key);
70 #ifdef CONFIG_DEBUG_LOCKDEP
71 seq_printf(m, " OPS:%8ld", debug_class_ops_read(class));
73 if (IS_ENABLED(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));
77 get_usage_chars(class, usage);
78 seq_printf(m, " %s", usage);
85 if (IS_ENABLED(CONFIG_PROVE_LOCKING)) {
86 list_for_each_entry(entry, &class->locks_after, entry) {
87 if (entry->distance == 1) {
88 seq_printf(m, " -> [%p] ", entry->class->key);
89 print_name(m, entry->class);
99 static const struct seq_operations lockdep_ops = {
106 #ifdef CONFIG_PROVE_LOCKING
107 static void *lc_start(struct seq_file *m, loff_t *pos)
113 return SEQ_START_TOKEN;
115 return lock_chains + (*pos - 1);
118 static void *lc_next(struct seq_file *m, void *v, loff_t *pos)
120 *pos = lockdep_next_lockchain(*pos - 1) + 1;
121 return lc_start(m, pos);
124 static void lc_stop(struct seq_file *m, void *v)
128 static int lc_show(struct seq_file *m, void *v)
130 struct lock_chain *chain = v;
131 struct lock_class *class;
133 static const char * const irq_strs[] = {
135 [LOCK_CHAIN_HARDIRQ_CONTEXT] = "hardirq",
136 [LOCK_CHAIN_SOFTIRQ_CONTEXT] = "softirq",
137 [LOCK_CHAIN_SOFTIRQ_CONTEXT|
138 LOCK_CHAIN_HARDIRQ_CONTEXT] = "hardirq|softirq",
141 if (v == SEQ_START_TOKEN) {
142 if (!nr_free_chain_hlocks)
143 seq_printf(m, "(buggered) ");
144 seq_printf(m, "all lock chains:\n");
148 seq_printf(m, "irq_context: %s\n", irq_strs[chain->irq_context]);
150 for (i = 0; i < chain->depth; i++) {
151 class = lock_chain_get_class(chain, i);
155 seq_printf(m, "[%p] ", class->key);
156 print_name(m, class);
164 static const struct seq_operations lockdep_chains_ops = {
170 #endif /* CONFIG_PROVE_LOCKING */
172 static void lockdep_stats_debug_show(struct seq_file *m)
174 #ifdef CONFIG_DEBUG_LOCKDEP
175 unsigned long long hi1 = debug_atomic_read(hardirqs_on_events),
176 hi2 = debug_atomic_read(hardirqs_off_events),
177 hr1 = debug_atomic_read(redundant_hardirqs_on),
178 hr2 = debug_atomic_read(redundant_hardirqs_off),
179 si1 = debug_atomic_read(softirqs_on_events),
180 si2 = debug_atomic_read(softirqs_off_events),
181 sr1 = debug_atomic_read(redundant_softirqs_on),
182 sr2 = debug_atomic_read(redundant_softirqs_off);
184 seq_printf(m, " chain lookup misses: %11llu\n",
185 debug_atomic_read(chain_lookup_misses));
186 seq_printf(m, " chain lookup hits: %11llu\n",
187 debug_atomic_read(chain_lookup_hits));
188 seq_printf(m, " cyclic checks: %11llu\n",
189 debug_atomic_read(nr_cyclic_checks));
190 seq_printf(m, " redundant checks: %11llu\n",
191 debug_atomic_read(nr_redundant_checks));
192 seq_printf(m, " redundant links: %11llu\n",
193 debug_atomic_read(nr_redundant));
194 seq_printf(m, " find-mask forwards checks: %11llu\n",
195 debug_atomic_read(nr_find_usage_forwards_checks));
196 seq_printf(m, " find-mask backwards checks: %11llu\n",
197 debug_atomic_read(nr_find_usage_backwards_checks));
199 seq_printf(m, " hardirq on events: %11llu\n", hi1);
200 seq_printf(m, " hardirq off events: %11llu\n", hi2);
201 seq_printf(m, " redundant hardirq ons: %11llu\n", hr1);
202 seq_printf(m, " redundant hardirq offs: %11llu\n", hr2);
203 seq_printf(m, " softirq on events: %11llu\n", si1);
204 seq_printf(m, " softirq off events: %11llu\n", si2);
205 seq_printf(m, " redundant softirq ons: %11llu\n", sr1);
206 seq_printf(m, " redundant softirq offs: %11llu\n", sr2);
210 static int lockdep_stats_show(struct seq_file *m, void *v)
212 unsigned long nr_unused = 0, nr_uncategorized = 0,
213 nr_irq_safe = 0, nr_irq_unsafe = 0,
214 nr_softirq_safe = 0, nr_softirq_unsafe = 0,
215 nr_hardirq_safe = 0, nr_hardirq_unsafe = 0,
216 nr_irq_read_safe = 0, nr_irq_read_unsafe = 0,
217 nr_softirq_read_safe = 0, nr_softirq_read_unsafe = 0,
218 nr_hardirq_read_safe = 0, nr_hardirq_read_unsafe = 0,
219 sum_forward_deps = 0;
221 #ifdef CONFIG_PROVE_LOCKING
222 struct lock_class *class;
224 list_for_each_entry(class, &all_lock_classes, lock_entry) {
226 if (class->usage_mask == 0)
228 if (class->usage_mask == LOCKF_USED)
230 if (class->usage_mask & LOCKF_USED_IN_IRQ)
232 if (class->usage_mask & LOCKF_ENABLED_IRQ)
234 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
236 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ)
238 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
240 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ)
242 if (class->usage_mask & LOCKF_USED_IN_IRQ_READ)
244 if (class->usage_mask & LOCKF_ENABLED_IRQ_READ)
245 nr_irq_read_unsafe++;
246 if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ)
247 nr_softirq_read_safe++;
248 if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ)
249 nr_softirq_read_unsafe++;
250 if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ)
251 nr_hardirq_read_safe++;
252 if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ)
253 nr_hardirq_read_unsafe++;
255 sum_forward_deps += lockdep_count_forward_deps(class);
257 #ifdef CONFIG_DEBUG_LOCKDEP
258 DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks) != nr_unused);
262 seq_printf(m, " lock-classes: %11lu [max: %lu]\n",
263 nr_lock_classes, MAX_LOCKDEP_KEYS);
264 seq_printf(m, " direct dependencies: %11lu [max: %lu]\n",
265 nr_list_entries, MAX_LOCKDEP_ENTRIES);
266 seq_printf(m, " indirect dependencies: %11lu\n",
270 * Total number of dependencies:
272 * All irq-safe locks may nest inside irq-unsafe locks,
273 * plus all the other known dependencies:
275 seq_printf(m, " all direct dependencies: %11lu\n",
276 nr_irq_unsafe * nr_irq_safe +
277 nr_hardirq_unsafe * nr_hardirq_safe +
280 #ifdef CONFIG_PROVE_LOCKING
281 seq_printf(m, " dependency chains: %11lu [max: %lu]\n",
282 lock_chain_count(), MAX_LOCKDEP_CHAINS);
283 seq_printf(m, " dependency chain hlocks used: %11lu [max: %lu]\n",
284 MAX_LOCKDEP_CHAIN_HLOCKS -
285 (nr_free_chain_hlocks + nr_lost_chain_hlocks),
286 MAX_LOCKDEP_CHAIN_HLOCKS);
287 seq_printf(m, " dependency chain hlocks lost: %11u\n",
288 nr_lost_chain_hlocks);
291 #ifdef CONFIG_TRACE_IRQFLAGS
292 seq_printf(m, " in-hardirq chains: %11u\n",
294 seq_printf(m, " in-softirq chains: %11u\n",
297 seq_printf(m, " in-process chains: %11u\n",
299 seq_printf(m, " stack-trace entries: %11lu [max: %lu]\n",
300 nr_stack_trace_entries, MAX_STACK_TRACE_ENTRIES);
301 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
302 seq_printf(m, " number of stack traces: %11llu\n",
303 lockdep_stack_trace_count());
304 seq_printf(m, " number of stack hash chains: %11llu\n",
305 lockdep_stack_hash_count());
307 seq_printf(m, " combined max dependencies: %11u\n",
308 (nr_hardirq_chains + 1) *
309 (nr_softirq_chains + 1) *
310 (nr_process_chains + 1)
312 seq_printf(m, " hardirq-safe locks: %11lu\n",
314 seq_printf(m, " hardirq-unsafe locks: %11lu\n",
316 seq_printf(m, " softirq-safe locks: %11lu\n",
318 seq_printf(m, " softirq-unsafe locks: %11lu\n",
320 seq_printf(m, " irq-safe locks: %11lu\n",
322 seq_printf(m, " irq-unsafe locks: %11lu\n",
325 seq_printf(m, " hardirq-read-safe locks: %11lu\n",
326 nr_hardirq_read_safe);
327 seq_printf(m, " hardirq-read-unsafe locks: %11lu\n",
328 nr_hardirq_read_unsafe);
329 seq_printf(m, " softirq-read-safe locks: %11lu\n",
330 nr_softirq_read_safe);
331 seq_printf(m, " softirq-read-unsafe locks: %11lu\n",
332 nr_softirq_read_unsafe);
333 seq_printf(m, " irq-read-safe locks: %11lu\n",
335 seq_printf(m, " irq-read-unsafe locks: %11lu\n",
338 seq_printf(m, " uncategorized locks: %11lu\n",
340 seq_printf(m, " unused locks: %11lu\n",
342 seq_printf(m, " max locking depth: %11u\n",
344 #ifdef CONFIG_PROVE_LOCKING
345 seq_printf(m, " max bfs queue depth: %11u\n",
346 max_bfs_queue_depth);
348 lockdep_stats_debug_show(m);
349 seq_printf(m, " debug_locks: %11u\n",
353 * Zapped classes and lockdep data buffers reuse statistics.
356 seq_printf(m, " zapped classes: %11lu\n",
358 #ifdef CONFIG_PROVE_LOCKING
359 seq_printf(m, " zapped lock chains: %11lu\n",
360 nr_zapped_lock_chains);
361 seq_printf(m, " large chain blocks: %11u\n",
362 nr_large_chain_blocks);
367 #ifdef CONFIG_LOCK_STAT
369 struct lock_stat_data {
370 struct lock_class *class;
371 struct lock_class_stats stats;
374 struct lock_stat_seq {
375 struct lock_stat_data *iter_end;
376 struct lock_stat_data stats[MAX_LOCKDEP_KEYS];
380 * sort on absolute number of contentions
382 static int lock_stat_cmp(const void *l, const void *r)
384 const struct lock_stat_data *dl = l, *dr = r;
385 unsigned long nl, nr;
387 nl = dl->stats.read_waittime.nr + dl->stats.write_waittime.nr;
388 nr = dr->stats.read_waittime.nr + dr->stats.write_waittime.nr;
393 static void seq_line(struct seq_file *m, char c, int offset, int length)
397 for (i = 0; i < offset; i++)
399 for (i = 0; i < length; i++)
400 seq_printf(m, "%c", c);
404 static void snprint_time(char *buf, size_t bufsiz, s64 nr)
409 nr += 5; /* for display rounding */
410 div = div_s64_rem(nr, 1000, &rem);
411 snprintf(buf, bufsiz, "%lld.%02d", (long long)div, (int)rem/10);
414 static void seq_time(struct seq_file *m, s64 time)
418 snprint_time(num, sizeof(num), time);
419 seq_printf(m, " %14s", num);
422 static void seq_lock_time(struct seq_file *m, struct lock_time *lt)
424 seq_printf(m, "%14lu", lt->nr);
425 seq_time(m, lt->min);
426 seq_time(m, lt->max);
427 seq_time(m, lt->total);
428 seq_time(m, lt->nr ? div64_u64(lt->total, lt->nr) : 0);
431 static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
433 const struct lockdep_subclass_key *ckey;
434 struct lock_class_stats *stats;
435 struct lock_class *class;
441 stats = &data->stats;
444 if (class->name_version > 1)
445 namelen -= 2; /* XXX truncates versions > 9 */
449 rcu_read_lock_sched();
450 cname = rcu_dereference_sched(class->name);
451 ckey = rcu_dereference_sched(class->key);
453 if (!cname && !ckey) {
454 rcu_read_unlock_sched();
458 char str[KSYM_NAME_LEN];
459 const char *key_name;
461 key_name = __get_key_name(ckey, str);
462 snprintf(name, namelen, "%s", key_name);
464 snprintf(name, namelen, "%s", cname);
466 rcu_read_unlock_sched();
468 namelen = strlen(name);
469 if (class->name_version > 1) {
470 snprintf(name+namelen, 3, "#%d", class->name_version);
473 if (class->subclass) {
474 snprintf(name+namelen, 3, "/%d", class->subclass);
478 if (stats->write_holdtime.nr) {
479 if (stats->read_holdtime.nr)
480 seq_printf(m, "%38s-W:", name);
482 seq_printf(m, "%40s:", name);
484 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]);
485 seq_lock_time(m, &stats->write_waittime);
486 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]);
487 seq_lock_time(m, &stats->write_holdtime);
491 if (stats->read_holdtime.nr) {
492 seq_printf(m, "%38s-R:", name);
493 seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]);
494 seq_lock_time(m, &stats->read_waittime);
495 seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]);
496 seq_lock_time(m, &stats->read_holdtime);
500 if (stats->read_waittime.nr + stats->write_waittime.nr == 0)
503 if (stats->read_holdtime.nr)
506 for (i = 0; i < LOCKSTAT_POINTS; i++) {
509 if (class->contention_point[i] == 0)
513 seq_line(m, '-', 40-namelen, namelen);
515 snprintf(ip, sizeof(ip), "[<%p>]",
516 (void *)class->contention_point[i]);
517 seq_printf(m, "%40s %14lu %29s %pS\n",
518 name, stats->contention_point[i],
519 ip, (void *)class->contention_point[i]);
521 for (i = 0; i < LOCKSTAT_POINTS; i++) {
524 if (class->contending_point[i] == 0)
528 seq_line(m, '-', 40-namelen, namelen);
530 snprintf(ip, sizeof(ip), "[<%p>]",
531 (void *)class->contending_point[i]);
532 seq_printf(m, "%40s %14lu %29s %pS\n",
533 name, stats->contending_point[i],
534 ip, (void *)class->contending_point[i]);
538 seq_line(m, '.', 0, 40 + 1 + 12 * (14 + 1));
543 static void seq_header(struct seq_file *m)
545 seq_puts(m, "lock_stat version 0.4\n");
547 if (unlikely(!debug_locks))
548 seq_printf(m, "*WARNING* lock debugging disabled!! - possibly due to a lockdep warning\n");
550 seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
551 seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s %14s %14s "
566 seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
570 static void *ls_start(struct seq_file *m, loff_t *pos)
572 struct lock_stat_seq *data = m->private;
573 struct lock_stat_data *iter;
576 return SEQ_START_TOKEN;
578 iter = data->stats + (*pos - 1);
579 if (iter >= data->iter_end)
585 static void *ls_next(struct seq_file *m, void *v, loff_t *pos)
588 return ls_start(m, pos);
591 static void ls_stop(struct seq_file *m, void *v)
595 static int ls_show(struct seq_file *m, void *v)
597 if (v == SEQ_START_TOKEN)
605 static const struct seq_operations lockstat_ops = {
612 static int lock_stat_open(struct inode *inode, struct file *file)
615 struct lock_class *class;
616 struct lock_stat_seq *data = vmalloc(sizeof(struct lock_stat_seq));
621 res = seq_open(file, &lockstat_ops);
623 struct lock_stat_data *iter = data->stats;
624 struct seq_file *m = file->private_data;
626 list_for_each_entry(class, &all_lock_classes, lock_entry) {
628 iter->stats = lock_stats(class);
631 data->iter_end = iter;
633 sort(data->stats, data->iter_end - data->stats,
634 sizeof(struct lock_stat_data),
635 lock_stat_cmp, NULL);
644 static ssize_t lock_stat_write(struct file *file, const char __user *buf,
645 size_t count, loff_t *ppos)
647 struct lock_class *class;
651 if (get_user(c, buf))
657 list_for_each_entry(class, &all_lock_classes, lock_entry)
658 clear_lock_stats(class);
663 static int lock_stat_release(struct inode *inode, struct file *file)
665 struct seq_file *seq = file->private_data;
668 return seq_release(inode, file);
671 static const struct proc_ops lock_stat_proc_ops = {
672 .proc_open = lock_stat_open,
673 .proc_write = lock_stat_write,
674 .proc_read = seq_read,
675 .proc_lseek = seq_lseek,
676 .proc_release = lock_stat_release,
678 #endif /* CONFIG_LOCK_STAT */
680 static int __init lockdep_proc_init(void)
682 proc_create_seq("lockdep", S_IRUSR, NULL, &lockdep_ops);
683 #ifdef CONFIG_PROVE_LOCKING
684 proc_create_seq("lockdep_chains", S_IRUSR, NULL, &lockdep_chains_ops);
686 proc_create_single("lockdep_stats", S_IRUSR, NULL, lockdep_stats_show);
687 #ifdef CONFIG_LOCK_STAT
688 proc_create("lock_stat", S_IRUSR | S_IWUSR, NULL, &lock_stat_proc_ops);
694 __initcall(lockdep_proc_init);