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-rw-r--r--kernel/perf_counter.c4962
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diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
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index e0d91fdf0c3c..000000000000
--- a/kernel/perf_counter.c
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1/*
2 * Performance counter core code
3 *
4 * Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
5 * Copyright (C) 2008-2009 Red Hat, Inc., Ingo Molnar
6 * Copyright (C) 2008-2009 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
7 * Copyright © 2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
8 *
9 * For licensing details see kernel-base/COPYING
10 */
11
12#include <linux/fs.h>
13#include <linux/mm.h>
14#include <linux/cpu.h>
15#include <linux/smp.h>
16#include <linux/file.h>
17#include <linux/poll.h>
18#include <linux/sysfs.h>
19#include <linux/dcache.h>
20#include <linux/percpu.h>
21#include <linux/ptrace.h>
22#include <linux/vmstat.h>
23#include <linux/hardirq.h>
24#include <linux/rculist.h>
25#include <linux/uaccess.h>
26#include <linux/syscalls.h>
27#include <linux/anon_inodes.h>
28#include <linux/kernel_stat.h>
29#include <linux/perf_counter.h>
30
31#include <asm/irq_regs.h>
32
33/*
34 * Each CPU has a list of per CPU counters:
35 */
36DEFINE_PER_CPU(struct perf_cpu_context, perf_cpu_context);
37
38int perf_max_counters __read_mostly = 1;
39static int perf_reserved_percpu __read_mostly;
40static int perf_overcommit __read_mostly = 1;
41
42static atomic_t nr_counters __read_mostly;
43static atomic_t nr_mmap_counters __read_mostly;
44static atomic_t nr_comm_counters __read_mostly;
45static atomic_t nr_task_counters __read_mostly;
46
47/*
48 * perf counter paranoia level:
49 * -1 - not paranoid at all
50 * 0 - disallow raw tracepoint access for unpriv
51 * 1 - disallow cpu counters for unpriv
52 * 2 - disallow kernel profiling for unpriv
53 */
54int sysctl_perf_counter_paranoid __read_mostly = 1;
55
56static inline bool perf_paranoid_tracepoint_raw(void)
57{
58 return sysctl_perf_counter_paranoid > -1;
59}
60
61static inline bool perf_paranoid_cpu(void)
62{
63 return sysctl_perf_counter_paranoid > 0;
64}
65
66static inline bool perf_paranoid_kernel(void)
67{
68 return sysctl_perf_counter_paranoid > 1;
69}
70
71int sysctl_perf_counter_mlock __read_mostly = 512; /* 'free' kb per user */
72
73/*
74 * max perf counter sample rate
75 */
76int sysctl_perf_counter_sample_rate __read_mostly = 100000;
77
78static atomic64_t perf_counter_id;
79
80/*
81 * Lock for (sysadmin-configurable) counter reservations:
82 */
83static DEFINE_SPINLOCK(perf_resource_lock);
84
85/*
86 * Architecture provided APIs - weak aliases:
87 */
88extern __weak const struct pmu *hw_perf_counter_init(struct perf_counter *counter)
89{
90 return NULL;
91}
92
93void __weak hw_perf_disable(void) { barrier(); }
94void __weak hw_perf_enable(void) { barrier(); }
95
96void __weak hw_perf_counter_setup(int cpu) { barrier(); }
97void __weak hw_perf_counter_setup_online(int cpu) { barrier(); }
98
99int __weak
100hw_perf_group_sched_in(struct perf_counter *group_leader,
101 struct perf_cpu_context *cpuctx,
102 struct perf_counter_context *ctx, int cpu)
103{
104 return 0;
105}
106
107void __weak perf_counter_print_debug(void) { }
108
109static DEFINE_PER_CPU(int, disable_count);
110
111void __perf_disable(void)
112{
113 __get_cpu_var(disable_count)++;
114}
115
116bool __perf_enable(void)
117{
118 return !--__get_cpu_var(disable_count);
119}
120
121void perf_disable(void)
122{
123 __perf_disable();
124 hw_perf_disable();
125}
126
127void perf_enable(void)
128{
129 if (__perf_enable())
130 hw_perf_enable();
131}
132
133static void get_ctx(struct perf_counter_context *ctx)
134{
135 WARN_ON(!atomic_inc_not_zero(&ctx->refcount));
136}
137
138static void free_ctx(struct rcu_head *head)
139{
140 struct perf_counter_context *ctx;
141
142 ctx = container_of(head, struct perf_counter_context, rcu_head);
143 kfree(ctx);
144}
145
146static void put_ctx(struct perf_counter_context *ctx)
147{
148 if (atomic_dec_and_test(&ctx->refcount)) {
149 if (ctx->parent_ctx)
150 put_ctx(ctx->parent_ctx);
151 if (ctx->task)
152 put_task_struct(ctx->task);
153 call_rcu(&ctx->rcu_head, free_ctx);
154 }
155}
156
157static void unclone_ctx(struct perf_counter_context *ctx)
158{
159 if (ctx->parent_ctx) {
160 put_ctx(ctx->parent_ctx);
161 ctx->parent_ctx = NULL;
162 }
163}
164
165/*
166 * If we inherit counters we want to return the parent counter id
167 * to userspace.
168 */
169static u64 primary_counter_id(struct perf_counter *counter)
170{
171 u64 id = counter->id;
172
173 if (counter->parent)
174 id = counter->parent->id;
175
176 return id;
177}
178
179/*
180 * Get the perf_counter_context for a task and lock it.
181 * This has to cope with with the fact that until it is locked,
182 * the context could get moved to another task.
183 */
184static struct perf_counter_context *
185perf_lock_task_context(struct task_struct *task, unsigned long *flags)
186{
187 struct perf_counter_context *ctx;
188
189 rcu_read_lock();
190 retry:
191 ctx = rcu_dereference(task->perf_counter_ctxp);
192 if (ctx) {
193 /*
194 * If this context is a clone of another, it might
195 * get swapped for another underneath us by
196 * perf_counter_task_sched_out, though the
197 * rcu_read_lock() protects us from any context
198 * getting freed. Lock the context and check if it
199 * got swapped before we could get the lock, and retry
200 * if so. If we locked the right context, then it
201 * can't get swapped on us any more.
202 */
203 spin_lock_irqsave(&ctx->lock, *flags);
204 if (ctx != rcu_dereference(task->perf_counter_ctxp)) {
205 spin_unlock_irqrestore(&ctx->lock, *flags);
206 goto retry;
207 }
208
209 if (!atomic_inc_not_zero(&ctx->refcount)) {
210 spin_unlock_irqrestore(&ctx->lock, *flags);
211 ctx = NULL;
212 }
213 }
214 rcu_read_unlock();
215 return ctx;
216}
217
218/*
219 * Get the context for a task and increment its pin_count so it
220 * can't get swapped to another task. This also increments its
221 * reference count so that the context can't get freed.
222 */
223static struct perf_counter_context *perf_pin_task_context(struct task_struct *task)
224{
225 struct perf_counter_context *ctx;
226 unsigned long flags;
227
228 ctx = perf_lock_task_context(task, &flags);
229 if (ctx) {
230 ++ctx->pin_count;
231 spin_unlock_irqrestore(&ctx->lock, flags);
232 }
233 return ctx;
234}
235
236static void perf_unpin_context(struct perf_counter_context *ctx)
237{
238 unsigned long flags;
239
240 spin_lock_irqsave(&ctx->lock, flags);
241 --ctx->pin_count;
242 spin_unlock_irqrestore(&ctx->lock, flags);
243 put_ctx(ctx);
244}
245
246/*
247 * Add a counter from the lists for its context.
248 * Must be called with ctx->mutex and ctx->lock held.
249 */
250static void
251list_add_counter(struct perf_counter *counter, struct perf_counter_context *ctx)
252{
253 struct perf_counter *group_leader = counter->group_leader;
254
255 /*
256 * Depending on whether it is a standalone or sibling counter,
257 * add it straight to the context's counter list, or to the group
258 * leader's sibling list:
259 */
260 if (group_leader == counter)
261 list_add_tail(&counter->list_entry, &ctx->counter_list);
262 else {
263 list_add_tail(&counter->list_entry, &group_leader->sibling_list);
264 group_leader->nr_siblings++;
265 }
266
267 list_add_rcu(&counter->event_entry, &ctx->event_list);
268 ctx->nr_counters++;
269 if (counter->attr.inherit_stat)
270 ctx->nr_stat++;
271}
272
273/*
274 * Remove a counter from the lists for its context.
275 * Must be called with ctx->mutex and ctx->lock held.
276 */
277static void
278list_del_counter(struct perf_counter *counter, struct perf_counter_context *ctx)
279{
280 struct perf_counter *sibling, *tmp;
281
282 if (list_empty(&counter->list_entry))
283 return;
284 ctx->nr_counters--;
285 if (counter->attr.inherit_stat)
286 ctx->nr_stat--;
287
288 list_del_init(&counter->list_entry);
289 list_del_rcu(&counter->event_entry);
290
291 if (counter->group_leader != counter)
292 counter->group_leader->nr_siblings--;
293
294 /*
295 * If this was a group counter with sibling counters then
296 * upgrade the siblings to singleton counters by adding them
297 * to the context list directly:
298 */
299 list_for_each_entry_safe(sibling, tmp,
300 &counter->sibling_list, list_entry) {
301
302 list_move_tail(&sibling->list_entry, &ctx->counter_list);
303 sibling->group_leader = sibling;
304 }
305}
306
307static void
308counter_sched_out(struct perf_counter *counter,
309 struct perf_cpu_context *cpuctx,
310 struct perf_counter_context *ctx)
311{
312 if (counter->state != PERF_COUNTER_STATE_ACTIVE)
313 return;
314
315 counter->state = PERF_COUNTER_STATE_INACTIVE;
316 if (counter->pending_disable) {
317 counter->pending_disable = 0;
318 counter->state = PERF_COUNTER_STATE_OFF;
319 }
320 counter->tstamp_stopped = ctx->time;
321 counter->pmu->disable(counter);
322 counter->oncpu = -1;
323
324 if (!is_software_counter(counter))
325 cpuctx->active_oncpu--;
326 ctx->nr_active--;
327 if (counter->attr.exclusive || !cpuctx->active_oncpu)
328 cpuctx->exclusive = 0;
329}
330
331static void
332group_sched_out(struct perf_counter *group_counter,
333 struct perf_cpu_context *cpuctx,
334 struct perf_counter_context *ctx)
335{
336 struct perf_counter *counter;
337
338 if (group_counter->state != PERF_COUNTER_STATE_ACTIVE)
339 return;
340
341 counter_sched_out(group_counter, cpuctx, ctx);
342
343 /*
344 * Schedule out siblings (if any):
345 */
346 list_for_each_entry(counter, &group_counter->sibling_list, list_entry)
347 counter_sched_out(counter, cpuctx, ctx);
348
349 if (group_counter->attr.exclusive)
350 cpuctx->exclusive = 0;
351}
352
353/*
354 * Cross CPU call to remove a performance counter
355 *
356 * We disable the counter on the hardware level first. After that we
357 * remove it from the context list.
358 */
359static void __perf_counter_remove_from_context(void *info)
360{
361 struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
362 struct perf_counter *counter = info;
363 struct perf_counter_context *ctx = counter->ctx;
364
365 /*
366 * If this is a task context, we need to check whether it is
367 * the current task context of this cpu. If not it has been
368 * scheduled out before the smp call arrived.
369 */
370 if (ctx->task && cpuctx->task_ctx != ctx)
371 return;
372
373 spin_lock(&ctx->lock);
374 /*
375 * Protect the list operation against NMI by disabling the
376 * counters on a global level.
377 */
378 perf_disable();
379
380 counter_sched_out(counter, cpuctx, ctx);
381
382 list_del_counter(counter, ctx);
383
384 if (!ctx->task) {
385 /*
386 * Allow more per task counters with respect to the
387 * reservation:
388 */
389 cpuctx->max_pertask =
390 min(perf_max_counters - ctx->nr_counters,
391 perf_max_counters - perf_reserved_percpu);
392 }
393
394 perf_enable();
395 spin_unlock(&ctx->lock);
396}
397
398
399/*
400 * Remove the counter from a task's (or a CPU's) list of counters.
401 *
402 * Must be called with ctx->mutex held.
403 *
404 * CPU counters are removed with a smp call. For task counters we only
405 * call when the task is on a CPU.
406 *
407 * If counter->ctx is a cloned context, callers must make sure that
408 * every task struct that counter->ctx->task could possibly point to
409 * remains valid. This is OK when called from perf_release since
410 * that only calls us on the top-level context, which can't be a clone.
411 * When called from perf_counter_exit_task, it's OK because the
412 * context has been detached from its task.
413 */
414static void perf_counter_remove_from_context(struct perf_counter *counter)
415{
416 struct perf_counter_context *ctx = counter->ctx;
417 struct task_struct *task = ctx->task;
418
419 if (!task) {
420 /*
421 * Per cpu counters are removed via an smp call and
422 * the removal is always sucessful.
423 */
424 smp_call_function_single(counter->cpu,
425 __perf_counter_remove_from_context,
426 counter, 1);
427 return;
428 }
429
430retry:
431 task_oncpu_function_call(task, __perf_counter_remove_from_context,
432 counter);
433
434 spin_lock_irq(&ctx->lock);
435 /*
436 * If the context is active we need to retry the smp call.
437 */
438 if (ctx->nr_active && !list_empty(&counter->list_entry)) {
439 spin_unlock_irq(&ctx->lock);
440 goto retry;
441 }
442
443 /*
444 * The lock prevents that this context is scheduled in so we
445 * can remove the counter safely, if the call above did not
446 * succeed.
447 */
448 if (!list_empty(&counter->list_entry)) {
449 list_del_counter(counter, ctx);
450 }
451 spin_unlock_irq(&ctx->lock);
452}
453
454static inline u64 perf_clock(void)
455{
456 return cpu_clock(smp_processor_id());
457}
458
459/*
460 * Update the record of the current time in a context.
461 */
462static void update_context_time(struct perf_counter_context *ctx)
463{
464 u64 now = perf_clock();
465
466 ctx->time += now - ctx->timestamp;
467 ctx->timestamp = now;
468}
469
470/*
471 * Update the total_time_enabled and total_time_running fields for a counter.
472 */
473static void update_counter_times(struct perf_counter *counter)
474{
475 struct perf_counter_context *ctx = counter->ctx;
476 u64 run_end;
477
478 if (counter->state < PERF_COUNTER_STATE_INACTIVE ||
479 counter->group_leader->state < PERF_COUNTER_STATE_INACTIVE)
480 return;
481
482 counter->total_time_enabled = ctx->time - counter->tstamp_enabled;
483
484 if (counter->state == PERF_COUNTER_STATE_INACTIVE)
485 run_end = counter->tstamp_stopped;
486 else
487 run_end = ctx->time;
488
489 counter->total_time_running = run_end - counter->tstamp_running;
490}
491
492/*
493 * Update total_time_enabled and total_time_running for all counters in a group.
494 */
495static void update_group_times(struct perf_counter *leader)
496{
497 struct perf_counter *counter;
498
499 update_counter_times(leader);
500 list_for_each_entry(counter, &leader->sibling_list, list_entry)
501 update_counter_times(counter);
502}
503
504/*
505 * Cross CPU call to disable a performance counter
506 */
507static void __perf_counter_disable(void *info)
508{
509 struct perf_counter *counter = info;
510 struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
511 struct perf_counter_context *ctx = counter->ctx;
512
513 /*
514 * If this is a per-task counter, need to check whether this
515 * counter's task is the current task on this cpu.
516 */
517 if (ctx->task && cpuctx->task_ctx != ctx)
518 return;
519
520 spin_lock(&ctx->lock);
521
522 /*
523 * If the counter is on, turn it off.
524 * If it is in error state, leave it in error state.
525 */
526 if (counter->state >= PERF_COUNTER_STATE_INACTIVE) {
527 update_context_time(ctx);
528 update_group_times(counter);
529 if (counter == counter->group_leader)
530 group_sched_out(counter, cpuctx, ctx);
531 else
532 counter_sched_out(counter, cpuctx, ctx);
533 counter->state = PERF_COUNTER_STATE_OFF;
534 }
535
536 spin_unlock(&ctx->lock);
537}
538
539/*
540 * Disable a counter.
541 *
542 * If counter->ctx is a cloned context, callers must make sure that
543 * every task struct that counter->ctx->task could possibly point to
544 * remains valid. This condition is satisifed when called through
545 * perf_counter_for_each_child or perf_counter_for_each because they
546 * hold the top-level counter's child_mutex, so any descendant that
547 * goes to exit will block in sync_child_counter.
548 * When called from perf_pending_counter it's OK because counter->ctx
549 * is the current context on this CPU and preemption is disabled,
550 * hence we can't get into perf_counter_task_sched_out for this context.
551 */
552static void perf_counter_disable(struct perf_counter *counter)
553{
554 struct perf_counter_context *ctx = counter->ctx;
555 struct task_struct *task = ctx->task;
556
557 if (!task) {
558 /*
559 * Disable the counter on the cpu that it's on
560 */
561 smp_call_function_single(counter->cpu, __perf_counter_disable,
562 counter, 1);
563 return;
564 }
565
566 retry:
567 task_oncpu_function_call(task, __perf_counter_disable, counter);
568
569 spin_lock_irq(&ctx->lock);
570 /*
571 * If the counter is still active, we need to retry the cross-call.
572 */
573 if (counter->state == PERF_COUNTER_STATE_ACTIVE) {
574 spin_unlock_irq(&ctx->lock);
575 goto retry;
576 }
577
578 /*
579 * Since we have the lock this context can't be scheduled
580 * in, so we can change the state safely.
581 */
582 if (counter->state == PERF_COUNTER_STATE_INACTIVE) {
583 update_group_times(counter);
584 counter->state = PERF_COUNTER_STATE_OFF;
585 }
586
587 spin_unlock_irq(&ctx->lock);
588}
589
590static int
591counter_sched_in(struct perf_counter *counter,
592 struct perf_cpu_context *cpuctx,
593 struct perf_counter_context *ctx,
594 int cpu)
595{
596 if (counter->state <= PERF_COUNTER_STATE_OFF)
597 return 0;
598
599 counter->state = PERF_COUNTER_STATE_ACTIVE;
600 counter->oncpu = cpu; /* TODO: put 'cpu' into cpuctx->cpu */
601 /*
602 * The new state must be visible before we turn it on in the hardware:
603 */
604 smp_wmb();
605
606 if (counter->pmu->enable(counter)) {
607 counter->state = PERF_COUNTER_STATE_INACTIVE;
608 counter->oncpu = -1;
609 return -EAGAIN;
610 }
611
612 counter->tstamp_running += ctx->time - counter->tstamp_stopped;
613
614 if (!is_software_counter(counter))
615 cpuctx->active_oncpu++;
616 ctx->nr_active++;
617
618 if (counter->attr.exclusive)
619 cpuctx->exclusive = 1;
620
621 return 0;
622}
623
624static int
625group_sched_in(struct perf_counter *group_counter,
626 struct perf_cpu_context *cpuctx,
627 struct perf_counter_context *ctx,
628 int cpu)
629{
630 struct perf_counter *counter, *partial_group;
631 int ret;
632
633 if (group_counter->state == PERF_COUNTER_STATE_OFF)
634 return 0;
635
636 ret = hw_perf_group_sched_in(group_counter, cpuctx, ctx, cpu);
637 if (ret)
638 return ret < 0 ? ret : 0;
639
640 if (counter_sched_in(group_counter, cpuctx, ctx, cpu))
641 return -EAGAIN;
642
643 /*
644 * Schedule in siblings as one group (if any):
645 */
646 list_for_each_entry(counter, &group_counter->sibling_list, list_entry) {
647 if (counter_sched_in(counter, cpuctx, ctx, cpu)) {
648 partial_group = counter;
649 goto group_error;
650 }
651 }
652
653 return 0;
654
655group_error:
656 /*
657 * Groups can be scheduled in as one unit only, so undo any
658 * partial group before returning:
659 */
660 list_for_each_entry(counter, &group_counter->sibling_list, list_entry) {
661 if (counter == partial_group)
662 break;
663 counter_sched_out(counter, cpuctx, ctx);
664 }
665 counter_sched_out(group_counter, cpuctx, ctx);
666
667 return -EAGAIN;
668}
669
670/*
671 * Return 1 for a group consisting entirely of software counters,
672 * 0 if the group contains any hardware counters.
673 */
674static int is_software_only_group(struct perf_counter *leader)
675{
676 struct perf_counter *counter;
677
678 if (!is_software_counter(leader))
679 return 0;
680
681 list_for_each_entry(counter, &leader->sibling_list, list_entry)
682 if (!is_software_counter(counter))
683 return 0;
684
685 return 1;
686}
687
688/*
689 * Work out whether we can put this counter group on the CPU now.
690 */
691static int group_can_go_on(struct perf_counter *counter,
692 struct perf_cpu_context *cpuctx,
693 int can_add_hw)
694{
695 /*
696 * Groups consisting entirely of software counters can always go on.
697 */
698 if (is_software_only_group(counter))
699 return 1;
700 /*
701 * If an exclusive group is already on, no other hardware
702 * counters can go on.
703 */
704 if (cpuctx->exclusive)
705 return 0;
706 /*
707 * If this group is exclusive and there are already
708 * counters on the CPU, it can't go on.
709 */
710 if (counter->attr.exclusive && cpuctx->active_oncpu)
711 return 0;
712 /*
713 * Otherwise, try to add it if all previous groups were able
714 * to go on.
715 */
716 return can_add_hw;
717}
718
719static void add_counter_to_ctx(struct perf_counter *counter,
720 struct perf_counter_context *ctx)
721{
722 list_add_counter(counter, ctx);
723 counter->tstamp_enabled = ctx->time;
724 counter->tstamp_running = ctx->time;
725 counter->tstamp_stopped = ctx->time;
726}
727
728/*
729 * Cross CPU call to install and enable a performance counter
730 *
731 * Must be called with ctx->mutex held
732 */
733static void __perf_install_in_context(void *info)
734{
735 struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
736 struct perf_counter *counter = info;
737 struct perf_counter_context *ctx = counter->ctx;
738 struct perf_counter *leader = counter->group_leader;
739 int cpu = smp_processor_id();
740 int err;
741
742 /*
743 * If this is a task context, we need to check whether it is
744 * the current task context of this cpu. If not it has been
745 * scheduled out before the smp call arrived.
746 * Or possibly this is the right context but it isn't
747 * on this cpu because it had no counters.
748 */
749 if (ctx->task && cpuctx->task_ctx != ctx) {
750 if (cpuctx->task_ctx || ctx->task != current)
751 return;
752 cpuctx->task_ctx = ctx;
753 }
754
755 spin_lock(&ctx->lock);
756 ctx->is_active = 1;
757 update_context_time(ctx);
758
759 /*
760 * Protect the list operation against NMI by disabling the
761 * counters on a global level. NOP for non NMI based counters.
762 */
763 perf_disable();
764
765 add_counter_to_ctx(counter, ctx);
766
767 /*
768 * Don't put the counter on if it is disabled or if
769 * it is in a group and the group isn't on.
770 */
771 if (counter->state != PERF_COUNTER_STATE_INACTIVE ||
772 (leader != counter && leader->state != PERF_COUNTER_STATE_ACTIVE))
773 goto unlock;
774
775 /*
776 * An exclusive counter can't go on if there are already active
777 * hardware counters, and no hardware counter can go on if there
778 * is already an exclusive counter on.
779 */
780 if (!group_can_go_on(counter, cpuctx, 1))
781 err = -EEXIST;
782 else
783 err = counter_sched_in(counter, cpuctx, ctx, cpu);
784
785 if (err) {
786 /*
787 * This counter couldn't go on. If it is in a group
788 * then we have to pull the whole group off.
789 * If the counter group is pinned then put it in error state.
790 */
791 if (leader != counter)
792 group_sched_out(leader, cpuctx, ctx);
793 if (leader->attr.pinned) {
794 update_group_times(leader);
795 leader->state = PERF_COUNTER_STATE_ERROR;
796 }
797 }
798
799 if (!err && !ctx->task && cpuctx->max_pertask)
800 cpuctx->max_pertask--;
801
802 unlock:
803 perf_enable();
804
805 spin_unlock(&ctx->lock);
806}
807
808/*
809 * Attach a performance counter to a context
810 *
811 * First we add the counter to the list with the hardware enable bit
812 * in counter->hw_config cleared.
813 *
814 * If the counter is attached to a task which is on a CPU we use a smp
815 * call to enable it in the task context. The task might have been
816 * scheduled away, but we check this in the smp call again.
817 *
818 * Must be called with ctx->mutex held.
819 */
820static void
821perf_install_in_context(struct perf_counter_context *ctx,
822 struct perf_counter *counter,
823 int cpu)
824{
825 struct task_struct *task = ctx->task;
826
827 if (!task) {
828 /*
829 * Per cpu counters are installed via an smp call and
830 * the install is always sucessful.
831 */
832 smp_call_function_single(cpu, __perf_install_in_context,
833 counter, 1);
834 return;
835 }
836
837retry:
838 task_oncpu_function_call(task, __perf_install_in_context,
839 counter);
840
841 spin_lock_irq(&ctx->lock);
842 /*
843 * we need to retry the smp call.
844 */
845 if (ctx->is_active && list_empty(&counter->list_entry)) {
846 spin_unlock_irq(&ctx->lock);
847 goto retry;
848 }
849
850 /*
851 * The lock prevents that this context is scheduled in so we
852 * can add the counter safely, if it the call above did not
853 * succeed.
854 */
855 if (list_empty(&counter->list_entry))
856 add_counter_to_ctx(counter, ctx);
857 spin_unlock_irq(&ctx->lock);
858}
859
860/*
861 * Put a counter into inactive state and update time fields.
862 * Enabling the leader of a group effectively enables all
863 * the group members that aren't explicitly disabled, so we
864 * have to update their ->tstamp_enabled also.
865 * Note: this works for group members as well as group leaders
866 * since the non-leader members' sibling_lists will be empty.
867 */
868static void __perf_counter_mark_enabled(struct perf_counter *counter,
869 struct perf_counter_context *ctx)
870{
871 struct perf_counter *sub;
872
873 counter->state = PERF_COUNTER_STATE_INACTIVE;
874 counter->tstamp_enabled = ctx->time - counter->total_time_enabled;
875 list_for_each_entry(sub, &counter->sibling_list, list_entry)
876 if (sub->state >= PERF_COUNTER_STATE_INACTIVE)
877 sub->tstamp_enabled =
878 ctx->time - sub->total_time_enabled;
879}
880
881/*
882 * Cross CPU call to enable a performance counter
883 */
884static void __perf_counter_enable(void *info)
885{
886 struct perf_counter *counter = info;
887 struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
888 struct perf_counter_context *ctx = counter->ctx;
889 struct perf_counter *leader = counter->group_leader;
890 int err;
891
892 /*
893 * If this is a per-task counter, need to check whether this
894 * counter's task is the current task on this cpu.
895 */
896 if (ctx->task && cpuctx->task_ctx != ctx) {
897 if (cpuctx->task_ctx || ctx->task != current)
898 return;
899 cpuctx->task_ctx = ctx;
900 }
901
902 spin_lock(&ctx->lock);
903 ctx->is_active = 1;
904 update_context_time(ctx);
905
906 if (counter->state >= PERF_COUNTER_STATE_INACTIVE)
907 goto unlock;
908 __perf_counter_mark_enabled(counter, ctx);
909
910 /*
911 * If the counter is in a group and isn't the group leader,
912 * then don't put it on unless the group is on.
913 */
914 if (leader != counter && leader->state != PERF_COUNTER_STATE_ACTIVE)
915 goto unlock;
916
917 if (!group_can_go_on(counter, cpuctx, 1)) {
918 err = -EEXIST;
919 } else {
920 perf_disable();
921 if (counter == leader)
922 err = group_sched_in(counter, cpuctx, ctx,
923 smp_processor_id());
924 else
925 err = counter_sched_in(counter, cpuctx, ctx,
926 smp_processor_id());
927 perf_enable();
928 }
929
930 if (err) {
931 /*
932 * If this counter can't go on and it's part of a
933 * group, then the whole group has to come off.
934 */
935 if (leader != counter)
936 group_sched_out(leader, cpuctx, ctx);
937 if (leader->attr.pinned) {
938 update_group_times(leader);
939 leader->state = PERF_COUNTER_STATE_ERROR;
940 }
941 }
942
943 unlock:
944 spin_unlock(&ctx->lock);
945}
946
947/*
948 * Enable a counter.
949 *
950 * If counter->ctx is a cloned context, callers must make sure that
951 * every task struct that counter->ctx->task could possibly point to
952 * remains valid. This condition is satisfied when called through
953 * perf_counter_for_each_child or perf_counter_for_each as described
954 * for perf_counter_disable.
955 */
956static void perf_counter_enable(struct perf_counter *counter)
957{
958 struct perf_counter_context *ctx = counter->ctx;
959 struct task_struct *task = ctx->task;
960
961 if (!task) {
962 /*
963 * Enable the counter on the cpu that it's on
964 */
965 smp_call_function_single(counter->cpu, __perf_counter_enable,
966 counter, 1);
967 return;
968 }
969
970 spin_lock_irq(&ctx->lock);
971 if (counter->state >= PERF_COUNTER_STATE_INACTIVE)
972 goto out;
973
974 /*
975 * If the counter is in error state, clear that first.
976 * That way, if we see the counter in error state below, we
977 * know that it has gone back into error state, as distinct
978 * from the task having been scheduled away before the
979 * cross-call arrived.
980 */
981 if (counter->state == PERF_COUNTER_STATE_ERROR)
982 counter->state = PERF_COUNTER_STATE_OFF;
983
984 retry:
985 spin_unlock_irq(&ctx->lock);
986 task_oncpu_function_call(task, __perf_counter_enable, counter);
987
988 spin_lock_irq(&ctx->lock);
989
990 /*
991 * If the context is active and the counter is still off,
992 * we need to retry the cross-call.
993 */
994 if (ctx->is_active && counter->state == PERF_COUNTER_STATE_OFF)
995 goto retry;
996
997 /*
998 * Since we have the lock this context can't be scheduled
999 * in, so we can change the state safely.
1000 */
1001 if (counter->state == PERF_COUNTER_STATE_OFF)
1002 __perf_counter_mark_enabled(counter, ctx);
1003
1004 out:
1005 spin_unlock_irq(&ctx->lock);
1006}
1007
1008static int perf_counter_refresh(struct perf_counter *counter, int refresh)
1009{
1010 /*
1011 * not supported on inherited counters
1012 */
1013 if (counter->attr.inherit)
1014 return -EINVAL;
1015
1016 atomic_add(refresh, &counter->event_limit);
1017 perf_counter_enable(counter);
1018
1019 return 0;
1020}
1021
1022void __perf_counter_sched_out(struct perf_counter_context *ctx,
1023 struct perf_cpu_context *cpuctx)
1024{
1025 struct perf_counter *counter;
1026
1027 spin_lock(&ctx->lock);
1028 ctx->is_active = 0;
1029 if (likely(!ctx->nr_counters))
1030 goto out;
1031 update_context_time(ctx);
1032
1033 perf_disable();
1034 if (ctx->nr_active) {
1035 list_for_each_entry(counter, &ctx->counter_list, list_entry) {
1036 if (counter != counter->group_leader)
1037 counter_sched_out(counter, cpuctx, ctx);
1038 else
1039 group_sched_out(counter, cpuctx, ctx);
1040 }
1041 }
1042 perf_enable();
1043 out:
1044 spin_unlock(&ctx->lock);
1045}
1046
1047/*
1048 * Test whether two contexts are equivalent, i.e. whether they
1049 * have both been cloned from the same version of the same context
1050 * and they both have the same number of enabled counters.
1051 * If the number of enabled counters is the same, then the set
1052 * of enabled counters should be the same, because these are both
1053 * inherited contexts, therefore we can't access individual counters
1054 * in them directly with an fd; we can only enable/disable all
1055 * counters via prctl, or enable/disable all counters in a family
1056 * via ioctl, which will have the same effect on both contexts.
1057 */
1058static int context_equiv(struct perf_counter_context *ctx1,
1059 struct perf_counter_context *ctx2)
1060{
1061 return ctx1->parent_ctx && ctx1->parent_ctx == ctx2->parent_ctx
1062 && ctx1->parent_gen == ctx2->parent_gen
1063 && !ctx1->pin_count && !ctx2->pin_count;
1064}
1065
1066static void __perf_counter_read(void *counter);
1067
1068static void __perf_counter_sync_stat(struct perf_counter *counter,
1069 struct perf_counter *next_counter)
1070{
1071 u64 value;
1072
1073 if (!counter->attr.inherit_stat)
1074 return;
1075
1076 /*
1077 * Update the counter value, we cannot use perf_counter_read()
1078 * because we're in the middle of a context switch and have IRQs
1079 * disabled, which upsets smp_call_function_single(), however
1080 * we know the counter must be on the current CPU, therefore we
1081 * don't need to use it.
1082 */
1083 switch (counter->state) {
1084 case PERF_COUNTER_STATE_ACTIVE:
1085 __perf_counter_read(counter);
1086 break;
1087
1088 case PERF_COUNTER_STATE_INACTIVE:
1089 update_counter_times(counter);
1090 break;
1091
1092 default:
1093 break;
1094 }
1095
1096 /*
1097 * In order to keep per-task stats reliable we need to flip the counter
1098 * values when we flip the contexts.
1099 */
1100 value = atomic64_read(&next_counter->count);
1101 value = atomic64_xchg(&counter->count, value);
1102 atomic64_set(&next_counter->count, value);
1103
1104 swap(counter->total_time_enabled, next_counter->total_time_enabled);
1105 swap(counter->total_time_running, next_counter->total_time_running);
1106
1107 /*
1108 * Since we swizzled the values, update the user visible data too.
1109 */
1110 perf_counter_update_userpage(counter);
1111 perf_counter_update_userpage(next_counter);
1112}
1113
1114#define list_next_entry(pos, member) \
1115 list_entry(pos->member.next, typeof(*pos), member)
1116
1117static void perf_counter_sync_stat(struct perf_counter_context *ctx,
1118 struct perf_counter_context *next_ctx)
1119{
1120 struct perf_counter *counter, *next_counter;
1121
1122 if (!ctx->nr_stat)
1123 return;
1124
1125 counter = list_first_entry(&ctx->event_list,
1126 struct perf_counter, event_entry);
1127
1128 next_counter = list_first_entry(&next_ctx->event_list,
1129 struct perf_counter, event_entry);
1130
1131 while (&counter->event_entry != &ctx->event_list &&
1132 &next_counter->event_entry != &next_ctx->event_list) {
1133
1134 __perf_counter_sync_stat(counter, next_counter);
1135
1136 counter = list_next_entry(counter, event_entry);
1137 next_counter = list_next_entry(next_counter, event_entry);
1138 }
1139}
1140
1141/*
1142 * Called from scheduler to remove the counters of the current task,
1143 * with interrupts disabled.
1144 *
1145 * We stop each counter and update the counter value in counter->count.
1146 *
1147 * This does not protect us against NMI, but disable()
1148 * sets the disabled bit in the control field of counter _before_
1149 * accessing the counter control register. If a NMI hits, then it will
1150 * not restart the counter.
1151 */
1152void perf_counter_task_sched_out(struct task_struct *task,
1153 struct task_struct *next, int cpu)
1154{
1155 struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
1156 struct perf_counter_context *ctx = task->perf_counter_ctxp;
1157 struct perf_counter_context *next_ctx;
1158 struct perf_counter_context *parent;
1159 struct pt_regs *regs;
1160 int do_switch = 1;
1161
1162 regs = task_pt_regs(task);
1163 perf_swcounter_event(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, 1, regs, 0);
1164
1165 if (likely(!ctx || !cpuctx->task_ctx))
1166 return;
1167
1168 update_context_time(ctx);
1169
1170 rcu_read_lock();
1171 parent = rcu_dereference(ctx->parent_ctx);
1172 next_ctx = next->perf_counter_ctxp;
1173 if (parent && next_ctx &&
1174 rcu_dereference(next_ctx->parent_ctx) == parent) {
1175 /*
1176 * Looks like the two contexts are clones, so we might be
1177 * able to optimize the context switch. We lock both
1178 * contexts and check that they are clones under the
1179 * lock (including re-checking that neither has been
1180 * uncloned in the meantime). It doesn't matter which
1181 * order we take the locks because no other cpu could
1182 * be trying to lock both of these tasks.
1183 */
1184 spin_lock(&ctx->lock);
1185 spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING);
1186 if (context_equiv(ctx, next_ctx)) {
1187 /*
1188 * XXX do we need a memory barrier of sorts
1189 * wrt to rcu_dereference() of perf_counter_ctxp
1190 */
1191 task->perf_counter_ctxp = next_ctx;
1192 next->perf_counter_ctxp = ctx;
1193 ctx->task = next;
1194 next_ctx->task = task;
1195 do_switch = 0;
1196
1197 perf_counter_sync_stat(ctx, next_ctx);
1198 }
1199 spin_unlock(&next_ctx->lock);
1200 spin_unlock(&ctx->lock);
1201 }
1202 rcu_read_unlock();
1203
1204 if (do_switch) {
1205 __perf_counter_sched_out(ctx, cpuctx);
1206 cpuctx->task_ctx = NULL;
1207 }
1208}
1209
1210/*
1211 * Called with IRQs disabled
1212 */
1213static void __perf_counter_task_sched_out(struct perf_counter_context *ctx)
1214{
1215 struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
1216
1217 if (!cpuctx->task_ctx)
1218 return;
1219
1220 if (WARN_ON_ONCE(ctx != cpuctx->task_ctx))
1221 return;
1222
1223 __perf_counter_sched_out(ctx, cpuctx);
1224 cpuctx->task_ctx = NULL;
1225}
1226
1227/*
1228 * Called with IRQs disabled
1229 */
1230static void perf_counter_cpu_sched_out(struct perf_cpu_context *cpuctx)
1231{
1232 __perf_counter_sched_out(&cpuctx->ctx, cpuctx);
1233}
1234
1235static void
1236__perf_counter_sched_in(struct perf_counter_context *ctx,
1237 struct perf_cpu_context *cpuctx, int cpu)
1238{
1239 struct perf_counter *counter;
1240 int can_add_hw = 1;
1241
1242 spin_lock(&ctx->lock);
1243 ctx->is_active = 1;
1244 if (likely(!ctx->nr_counters))
1245 goto out;
1246
1247 ctx->timestamp = perf_clock();
1248
1249 perf_disable();
1250
1251 /*
1252 * First go through the list and put on any pinned groups
1253 * in order to give them the best chance of going on.
1254 */
1255 list_for_each_entry(counter, &ctx->counter_list, list_entry) {
1256 if (counter->state <= PERF_COUNTER_STATE_OFF ||
1257 !counter->attr.pinned)
1258 continue;
1259 if (counter->cpu != -1 && counter->cpu != cpu)
1260 continue;
1261
1262 if (counter != counter->group_leader)
1263 counter_sched_in(counter, cpuctx, ctx, cpu);
1264 else {
1265 if (group_can_go_on(counter, cpuctx, 1))
1266 group_sched_in(counter, cpuctx, ctx, cpu);
1267 }
1268
1269 /*
1270 * If this pinned group hasn't been scheduled,
1271 * put it in error state.
1272 */
1273 if (counter->state == PERF_COUNTER_STATE_INACTIVE) {
1274 update_group_times(counter);
1275 counter->state = PERF_COUNTER_STATE_ERROR;
1276 }
1277 }
1278
1279 list_for_each_entry(counter, &ctx->counter_list, list_entry) {
1280 /*
1281 * Ignore counters in OFF or ERROR state, and
1282 * ignore pinned counters since we did them already.
1283 */
1284 if (counter->state <= PERF_COUNTER_STATE_OFF ||
1285 counter->attr.pinned)
1286 continue;
1287
1288 /*
1289 * Listen to the 'cpu' scheduling filter constraint
1290 * of counters:
1291 */
1292 if (counter->cpu != -1 && counter->cpu != cpu)
1293 continue;
1294
1295 if (counter != counter->group_leader) {
1296 if (counter_sched_in(counter, cpuctx, ctx, cpu))
1297 can_add_hw = 0;
1298 } else {
1299 if (group_can_go_on(counter, cpuctx, can_add_hw)) {
1300 if (group_sched_in(counter, cpuctx, ctx, cpu))
1301 can_add_hw = 0;
1302 }
1303 }
1304 }
1305 perf_enable();
1306 out:
1307 spin_unlock(&ctx->lock);
1308}
1309
1310/*
1311 * Called from scheduler to add the counters of the current task
1312 * with interrupts disabled.
1313 *
1314 * We restore the counter value and then enable it.
1315 *
1316 * This does not protect us against NMI, but enable()
1317 * sets the enabled bit in the control field of counter _before_
1318 * accessing the counter control register. If a NMI hits, then it will
1319 * keep the counter running.
1320 */
1321void perf_counter_task_sched_in(struct task_struct *task, int cpu)
1322{
1323 struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
1324 struct perf_counter_context *ctx = task->perf_counter_ctxp;
1325
1326 if (likely(!ctx))
1327 return;
1328 if (cpuctx->task_ctx == ctx)
1329 return;
1330 __perf_counter_sched_in(ctx, cpuctx, cpu);
1331 cpuctx->task_ctx = ctx;
1332}
1333
1334static void perf_counter_cpu_sched_in(struct perf_cpu_context *cpuctx, int cpu)
1335{
1336 struct perf_counter_context *ctx = &cpuctx->ctx;
1337
1338 __perf_counter_sched_in(ctx, cpuctx, cpu);
1339}
1340
1341#define MAX_INTERRUPTS (~0ULL)
1342
1343static void perf_log_throttle(struct perf_counter *counter, int enable);
1344
1345static void perf_adjust_period(struct perf_counter *counter, u64 events)
1346{
1347 struct hw_perf_counter *hwc = &counter->hw;
1348 u64 period, sample_period;
1349 s64 delta;
1350
1351 events *= hwc->sample_period;
1352 period = div64_u64(events, counter->attr.sample_freq);
1353
1354 delta = (s64)(period - hwc->sample_period);
1355 delta = (delta + 7) / 8; /* low pass filter */
1356
1357 sample_period = hwc->sample_period + delta;
1358
1359 if (!sample_period)
1360 sample_period = 1;
1361
1362 hwc->sample_period = sample_period;
1363}
1364
1365static void perf_ctx_adjust_freq(struct perf_counter_context *ctx)
1366{
1367 struct perf_counter *counter;
1368 struct hw_perf_counter *hwc;
1369 u64 interrupts, freq;
1370
1371 spin_lock(&ctx->lock);
1372 list_for_each_entry(counter, &ctx->counter_list, list_entry) {
1373 if (counter->state != PERF_COUNTER_STATE_ACTIVE)
1374 continue;
1375
1376 hwc = &counter->hw;
1377
1378 interrupts = hwc->interrupts;
1379 hwc->interrupts = 0;
1380
1381 /*
1382 * unthrottle counters on the tick
1383 */
1384 if (interrupts == MAX_INTERRUPTS) {
1385 perf_log_throttle(counter, 1);
1386 counter->pmu->unthrottle(counter);
1387 interrupts = 2*sysctl_perf_counter_sample_rate/HZ;
1388 }
1389
1390 if (!counter->attr.freq || !counter->attr.sample_freq)
1391 continue;
1392
1393 /*
1394 * if the specified freq < HZ then we need to skip ticks
1395 */
1396 if (counter->attr.sample_freq < HZ) {
1397 freq = counter->attr.sample_freq;
1398
1399 hwc->freq_count += freq;
1400 hwc->freq_interrupts += interrupts;
1401
1402 if (hwc->freq_count < HZ)
1403 continue;
1404
1405 interrupts = hwc->freq_interrupts;
1406 hwc->freq_interrupts = 0;
1407 hwc->freq_count -= HZ;
1408 } else
1409 freq = HZ;
1410
1411 perf_adjust_period(counter, freq * interrupts);
1412
1413 /*
1414 * In order to avoid being stalled by an (accidental) huge
1415 * sample period, force reset the sample period if we didn't
1416 * get any events in this freq period.
1417 */
1418 if (!interrupts) {
1419 perf_disable();
1420 counter->pmu->disable(counter);
1421 atomic64_set(&hwc->period_left, 0);
1422 counter->pmu->enable(counter);
1423 perf_enable();
1424 }
1425 }
1426 spin_unlock(&ctx->lock);
1427}
1428
1429/*
1430 * Round-robin a context's counters:
1431 */
1432static void rotate_ctx(struct perf_counter_context *ctx)
1433{
1434 struct perf_counter *counter;
1435
1436 if (!ctx->nr_counters)
1437 return;
1438
1439 spin_lock(&ctx->lock);
1440 /*
1441 * Rotate the first entry last (works just fine for group counters too):
1442 */
1443 perf_disable();
1444 list_for_each_entry(counter, &ctx->counter_list, list_entry) {
1445 list_move_tail(&counter->list_entry, &ctx->counter_list);
1446 break;
1447 }
1448 perf_enable();
1449
1450 spin_unlock(&ctx->lock);
1451}
1452
1453void perf_counter_task_tick(struct task_struct *curr, int cpu)
1454{
1455 struct perf_cpu_context *cpuctx;
1456 struct perf_counter_context *ctx;
1457
1458 if (!atomic_read(&nr_counters))
1459 return;
1460
1461 cpuctx = &per_cpu(perf_cpu_context, cpu);
1462 ctx = curr->perf_counter_ctxp;
1463
1464 perf_ctx_adjust_freq(&cpuctx->ctx);
1465 if (ctx)
1466 perf_ctx_adjust_freq(ctx);
1467
1468 perf_counter_cpu_sched_out(cpuctx);
1469 if (ctx)
1470 __perf_counter_task_sched_out(ctx);
1471
1472 rotate_ctx(&cpuctx->ctx);
1473 if (ctx)
1474 rotate_ctx(ctx);
1475
1476 perf_counter_cpu_sched_in(cpuctx, cpu);
1477 if (ctx)
1478 perf_counter_task_sched_in(curr, cpu);
1479}
1480
1481/*
1482 * Enable all of a task's counters that have been marked enable-on-exec.
1483 * This expects task == current.
1484 */
1485static void perf_counter_enable_on_exec(struct task_struct *task)
1486{
1487 struct perf_counter_context *ctx;
1488 struct perf_counter *counter;
1489 unsigned long flags;
1490 int enabled = 0;
1491
1492 local_irq_save(flags);
1493 ctx = task->perf_counter_ctxp;
1494 if (!ctx || !ctx->nr_counters)
1495 goto out;
1496
1497 __perf_counter_task_sched_out(ctx);
1498
1499 spin_lock(&ctx->lock);
1500
1501 list_for_each_entry(counter, &ctx->counter_list, list_entry) {
1502 if (!counter->attr.enable_on_exec)
1503 continue;
1504 counter->attr.enable_on_exec = 0;
1505 if (counter->state >= PERF_COUNTER_STATE_INACTIVE)
1506 continue;
1507 __perf_counter_mark_enabled(counter, ctx);
1508 enabled = 1;
1509 }
1510
1511 /*
1512 * Unclone this context if we enabled any counter.
1513 */
1514 if (enabled)
1515 unclone_ctx(ctx);
1516
1517 spin_unlock(&ctx->lock);
1518
1519 perf_counter_task_sched_in(task, smp_processor_id());
1520 out:
1521 local_irq_restore(flags);
1522}
1523
1524/*
1525 * Cross CPU call to read the hardware counter
1526 */
1527static void __perf_counter_read(void *info)
1528{
1529 struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
1530 struct perf_counter *counter = info;
1531 struct perf_counter_context *ctx = counter->ctx;
1532 unsigned long flags;
1533
1534 /*
1535 * If this is a task context, we need to check whether it is
1536 * the current task context of this cpu. If not it has been
1537 * scheduled out before the smp call arrived. In that case
1538 * counter->count would have been updated to a recent sample
1539 * when the counter was scheduled out.
1540 */
1541 if (ctx->task && cpuctx->task_ctx != ctx)
1542 return;
1543
1544 local_irq_save(flags);
1545 if (ctx->is_active)
1546 update_context_time(ctx);
1547 counter->pmu->read(counter);
1548 update_counter_times(counter);
1549 local_irq_restore(flags);
1550}
1551
1552static u64 perf_counter_read(struct perf_counter *counter)
1553{
1554 /*
1555 * If counter is enabled and currently active on a CPU, update the
1556 * value in the counter structure:
1557 */
1558 if (counter->state == PERF_COUNTER_STATE_ACTIVE) {
1559 smp_call_function_single(counter->oncpu,
1560 __perf_counter_read, counter, 1);
1561 } else if (counter->state == PERF_COUNTER_STATE_INACTIVE) {
1562 update_counter_times(counter);
1563 }
1564
1565 return atomic64_read(&counter->count);
1566}
1567
1568/*
1569 * Initialize the perf_counter context in a task_struct:
1570 */
1571static void
1572__perf_counter_init_context(struct perf_counter_context *ctx,
1573 struct task_struct *task)
1574{
1575 memset(ctx, 0, sizeof(*ctx));
1576 spin_lock_init(&ctx->lock);
1577 mutex_init(&ctx->mutex);
1578 INIT_LIST_HEAD(&ctx->counter_list);
1579 INIT_LIST_HEAD(&ctx->event_list);
1580 atomic_set(&ctx->refcount, 1);
1581 ctx->task = task;
1582}
1583
1584static struct perf_counter_context *find_get_context(pid_t pid, int cpu)
1585{
1586 struct perf_counter_context *ctx;
1587 struct perf_cpu_context *cpuctx;
1588 struct task_struct *task;
1589 unsigned long flags;
1590 int err;
1591
1592 /*
1593 * If cpu is not a wildcard then this is a percpu counter:
1594 */
1595 if (cpu != -1) {
1596 /* Must be root to operate on a CPU counter: */
1597 if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
1598 return ERR_PTR(-EACCES);
1599
1600 if (cpu < 0 || cpu > num_possible_cpus())
1601 return ERR_PTR(-EINVAL);
1602
1603 /*
1604 * We could be clever and allow to attach a counter to an
1605 * offline CPU and activate it when the CPU comes up, but
1606 * that's for later.
1607 */
1608 if (!cpu_isset(cpu, cpu_online_map))
1609 return ERR_PTR(-ENODEV);
1610
1611 cpuctx = &per_cpu(perf_cpu_context, cpu);
1612 ctx = &cpuctx->ctx;
1613 get_ctx(ctx);
1614
1615 return ctx;
1616 }
1617
1618 rcu_read_lock();
1619 if (!pid)
1620 task = current;
1621 else
1622 task = find_task_by_vpid(pid);
1623 if (task)
1624 get_task_struct(task);
1625 rcu_read_unlock();
1626
1627 if (!task)
1628 return ERR_PTR(-ESRCH);
1629
1630 /*
1631 * Can't attach counters to a dying task.
1632 */
1633 err = -ESRCH;
1634 if (task->flags & PF_EXITING)
1635 goto errout;
1636
1637 /* Reuse ptrace permission checks for now. */
1638 err = -EACCES;
1639 if (!ptrace_may_access(task, PTRACE_MODE_READ))
1640 goto errout;
1641
1642 retry:
1643 ctx = perf_lock_task_context(task, &flags);
1644 if (ctx) {
1645 unclone_ctx(ctx);
1646 spin_unlock_irqrestore(&ctx->lock, flags);
1647 }
1648
1649 if (!ctx) {
1650 ctx = kmalloc(sizeof(struct perf_counter_context), GFP_KERNEL);
1651 err = -ENOMEM;
1652 if (!ctx)
1653 goto errout;
1654 __perf_counter_init_context(ctx, task);
1655 get_ctx(ctx);
1656 if (cmpxchg(&task->perf_counter_ctxp, NULL, ctx)) {
1657 /*
1658 * We raced with some other task; use
1659 * the context they set.
1660 */
1661 kfree(ctx);
1662 goto retry;
1663 }
1664 get_task_struct(task);
1665 }
1666
1667 put_task_struct(task);
1668 return ctx;
1669
1670 errout:
1671 put_task_struct(task);
1672 return ERR_PTR(err);
1673}
1674
1675static void free_counter_rcu(struct rcu_head *head)
1676{
1677 struct perf_counter *counter;
1678
1679 counter = container_of(head, struct perf_counter, rcu_head);
1680 if (counter->ns)
1681 put_pid_ns(counter->ns);
1682 kfree(counter);
1683}
1684
1685static void perf_pending_sync(struct perf_counter *counter);
1686
1687static void free_counter(struct perf_counter *counter)
1688{
1689 perf_pending_sync(counter);
1690
1691 if (!counter->parent) {
1692 atomic_dec(&nr_counters);
1693 if (counter->attr.mmap)
1694 atomic_dec(&nr_mmap_counters);
1695 if (counter->attr.comm)
1696 atomic_dec(&nr_comm_counters);
1697 if (counter->attr.task)
1698 atomic_dec(&nr_task_counters);
1699 }
1700
1701 if (counter->output) {
1702 fput(counter->output->filp);
1703 counter->output = NULL;
1704 }
1705
1706 if (counter->destroy)
1707 counter->destroy(counter);
1708
1709 put_ctx(counter->ctx);
1710 call_rcu(&counter->rcu_head, free_counter_rcu);
1711}
1712
1713/*
1714 * Called when the last reference to the file is gone.
1715 */
1716static int perf_release(struct inode *inode, struct file *file)
1717{
1718 struct perf_counter *counter = file->private_data;
1719 struct perf_counter_context *ctx = counter->ctx;
1720
1721 file->private_data = NULL;
1722
1723 WARN_ON_ONCE(ctx->parent_ctx);
1724 mutex_lock(&ctx->mutex);
1725 perf_counter_remove_from_context(counter);
1726 mutex_unlock(&ctx->mutex);
1727
1728 mutex_lock(&counter->owner->perf_counter_mutex);
1729 list_del_init(&counter->owner_entry);
1730 mutex_unlock(&counter->owner->perf_counter_mutex);
1731 put_task_struct(counter->owner);
1732
1733 free_counter(counter);
1734
1735 return 0;
1736}
1737
1738static int perf_counter_read_size(struct perf_counter *counter)
1739{
1740 int entry = sizeof(u64); /* value */
1741 int size = 0;
1742 int nr = 1;
1743
1744 if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
1745 size += sizeof(u64);
1746
1747 if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
1748 size += sizeof(u64);
1749
1750 if (counter->attr.read_format & PERF_FORMAT_ID)
1751 entry += sizeof(u64);
1752
1753 if (counter->attr.read_format & PERF_FORMAT_GROUP) {
1754 nr += counter->group_leader->nr_siblings;
1755 size += sizeof(u64);
1756 }
1757
1758 size += entry * nr;
1759
1760 return size;
1761}
1762
1763static u64 perf_counter_read_value(struct perf_counter *counter)
1764{
1765 struct perf_counter *child;
1766 u64 total = 0;
1767
1768 total += perf_counter_read(counter);
1769 list_for_each_entry(child, &counter->child_list, child_list)
1770 total += perf_counter_read(child);
1771
1772 return total;
1773}
1774
1775static int perf_counter_read_entry(struct perf_counter *counter,
1776 u64 read_format, char __user *buf)
1777{
1778 int n = 0, count = 0;
1779 u64 values[2];
1780
1781 values[n++] = perf_counter_read_value(counter);
1782 if (read_format & PERF_FORMAT_ID)
1783 values[n++] = primary_counter_id(counter);
1784
1785 count = n * sizeof(u64);
1786
1787 if (copy_to_user(buf, values, count))
1788 return -EFAULT;
1789
1790 return count;
1791}
1792
1793static int perf_counter_read_group(struct perf_counter *counter,
1794 u64 read_format, char __user *buf)
1795{
1796 struct perf_counter *leader = counter->group_leader, *sub;
1797 int n = 0, size = 0, err = -EFAULT;
1798 u64 values[3];
1799
1800 values[n++] = 1 + leader->nr_siblings;
1801 if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
1802 values[n++] = leader->total_time_enabled +
1803 atomic64_read(&leader->child_total_time_enabled);
1804 }
1805 if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
1806 values[n++] = leader->total_time_running +
1807 atomic64_read(&leader->child_total_time_running);
1808 }
1809
1810 size = n * sizeof(u64);
1811
1812 if (copy_to_user(buf, values, size))
1813 return -EFAULT;
1814
1815 err = perf_counter_read_entry(leader, read_format, buf + size);
1816 if (err < 0)
1817 return err;
1818
1819 size += err;
1820
1821 list_for_each_entry(sub, &leader->sibling_list, list_entry) {
1822 err = perf_counter_read_entry(sub, read_format,
1823 buf + size);
1824 if (err < 0)
1825 return err;
1826
1827 size += err;
1828 }
1829
1830 return size;
1831}
1832
1833static int perf_counter_read_one(struct perf_counter *counter,
1834 u64 read_format, char __user *buf)
1835{
1836 u64 values[4];
1837 int n = 0;
1838
1839 values[n++] = perf_counter_read_value(counter);
1840 if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
1841 values[n++] = counter->total_time_enabled +
1842 atomic64_read(&counter->child_total_time_enabled);
1843 }
1844 if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
1845 values[n++] = counter->total_time_running +
1846 atomic64_read(&counter->child_total_time_running);
1847 }
1848 if (read_format & PERF_FORMAT_ID)
1849 values[n++] = primary_counter_id(counter);
1850
1851 if (copy_to_user(buf, values, n * sizeof(u64)))
1852 return -EFAULT;
1853
1854 return n * sizeof(u64);
1855}
1856
1857/*
1858 * Read the performance counter - simple non blocking version for now
1859 */
1860static ssize_t
1861perf_read_hw(struct perf_counter *counter, char __user *buf, size_t count)
1862{
1863 u64 read_format = counter->attr.read_format;
1864 int ret;
1865
1866 /*
1867 * Return end-of-file for a read on a counter that is in
1868 * error state (i.e. because it was pinned but it couldn't be
1869 * scheduled on to the CPU at some point).
1870 */
1871 if (counter->state == PERF_COUNTER_STATE_ERROR)
1872 return 0;
1873
1874 if (count < perf_counter_read_size(counter))
1875 return -ENOSPC;
1876
1877 WARN_ON_ONCE(counter->ctx->parent_ctx);
1878 mutex_lock(&counter->child_mutex);
1879 if (read_format & PERF_FORMAT_GROUP)
1880 ret = perf_counter_read_group(counter, read_format, buf);
1881 else
1882 ret = perf_counter_read_one(counter, read_format, buf);
1883 mutex_unlock(&counter->child_mutex);
1884
1885 return ret;
1886}
1887
1888static ssize_t
1889perf_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
1890{
1891 struct perf_counter *counter = file->private_data;
1892
1893 return perf_read_hw(counter, buf, count);
1894}
1895
1896static unsigned int perf_poll(struct file *file, poll_table *wait)
1897{
1898 struct perf_counter *counter = file->private_data;
1899 struct perf_mmap_data *data;
1900 unsigned int events = POLL_HUP;
1901
1902 rcu_read_lock();
1903 data = rcu_dereference(counter->data);
1904 if (data)
1905 events = atomic_xchg(&data->poll, 0);
1906 rcu_read_unlock();
1907
1908 poll_wait(file, &counter->waitq, wait);
1909
1910 return events;
1911}
1912
1913static void perf_counter_reset(struct perf_counter *counter)
1914{
1915 (void)perf_counter_read(counter);
1916 atomic64_set(&counter->count, 0);
1917 perf_counter_update_userpage(counter);
1918}
1919
1920/*
1921 * Holding the top-level counter's child_mutex means that any
1922 * descendant process that has inherited this counter will block
1923 * in sync_child_counter if it goes to exit, thus satisfying the
1924 * task existence requirements of perf_counter_enable/disable.
1925 */
1926static void perf_counter_for_each_child(struct perf_counter *counter,
1927 void (*func)(struct perf_counter *))
1928{
1929 struct perf_counter *child;
1930
1931 WARN_ON_ONCE(counter->ctx->parent_ctx);
1932 mutex_lock(&counter->child_mutex);
1933 func(counter);
1934 list_for_each_entry(child, &counter->child_list, child_list)
1935 func(child);
1936 mutex_unlock(&counter->child_mutex);
1937}
1938
1939static void perf_counter_for_each(struct perf_counter *counter,
1940 void (*func)(struct perf_counter *))
1941{
1942 struct perf_counter_context *ctx = counter->ctx;
1943 struct perf_counter *sibling;
1944
1945 WARN_ON_ONCE(ctx->parent_ctx);
1946 mutex_lock(&ctx->mutex);
1947 counter = counter->group_leader;
1948
1949 perf_counter_for_each_child(counter, func);
1950 func(counter);
1951 list_for_each_entry(sibling, &counter->sibling_list, list_entry)
1952 perf_counter_for_each_child(counter, func);
1953 mutex_unlock(&ctx->mutex);
1954}
1955
1956static int perf_counter_period(struct perf_counter *counter, u64 __user *arg)
1957{
1958 struct perf_counter_context *ctx = counter->ctx;
1959 unsigned long size;
1960 int ret = 0;
1961 u64 value;
1962
1963 if (!counter->attr.sample_period)
1964 return -EINVAL;
1965
1966 size = copy_from_user(&value, arg, sizeof(value));
1967 if (size != sizeof(value))
1968 return -EFAULT;
1969
1970 if (!value)
1971 return -EINVAL;
1972
1973 spin_lock_irq(&ctx->lock);
1974 if (counter->attr.freq) {
1975 if (value > sysctl_perf_counter_sample_rate) {
1976 ret = -EINVAL;
1977 goto unlock;
1978 }
1979
1980 counter->attr.sample_freq = value;
1981 } else {
1982 counter->attr.sample_period = value;
1983 counter->hw.sample_period = value;
1984 }
1985unlock:
1986 spin_unlock_irq(&ctx->lock);
1987
1988 return ret;
1989}
1990
1991int perf_counter_set_output(struct perf_counter *counter, int output_fd);
1992
1993static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1994{
1995 struct perf_counter *counter = file->private_data;
1996 void (*func)(struct perf_counter *);
1997 u32 flags = arg;
1998
1999 switch (cmd) {
2000 case PERF_COUNTER_IOC_ENABLE:
2001 func = perf_counter_enable;
2002 break;
2003 case PERF_COUNTER_IOC_DISABLE:
2004 func = perf_counter_disable;
2005 break;
2006 case PERF_COUNTER_IOC_RESET:
2007 func = perf_counter_reset;
2008 break;
2009
2010 case PERF_COUNTER_IOC_REFRESH:
2011 return perf_counter_refresh(counter, arg);
2012
2013 case PERF_COUNTER_IOC_PERIOD:
2014 return perf_counter_period(counter, (u64 __user *)arg);
2015
2016 case PERF_COUNTER_IOC_SET_OUTPUT:
2017 return perf_counter_set_output(counter, arg);
2018
2019 default:
2020 return -ENOTTY;
2021 }
2022
2023 if (flags & PERF_IOC_FLAG_GROUP)
2024 perf_counter_for_each(counter, func);
2025 else
2026 perf_counter_for_each_child(counter, func);
2027
2028 return 0;
2029}
2030
2031int perf_counter_task_enable(void)
2032{
2033 struct perf_counter *counter;
2034
2035 mutex_lock(&current->perf_counter_mutex);
2036 list_for_each_entry(counter, &current->perf_counter_list, owner_entry)
2037 perf_counter_for_each_child(counter, perf_counter_enable);
2038 mutex_unlock(&current->perf_counter_mutex);
2039
2040 return 0;
2041}
2042
2043int perf_counter_task_disable(void)
2044{
2045 struct perf_counter *counter;
2046
2047 mutex_lock(&current->perf_counter_mutex);
2048 list_for_each_entry(counter, &current->perf_counter_list, owner_entry)
2049 perf_counter_for_each_child(counter, perf_counter_disable);
2050 mutex_unlock(&current->perf_counter_mutex);
2051
2052 return 0;
2053}
2054
2055#ifndef PERF_COUNTER_INDEX_OFFSET
2056# define PERF_COUNTER_INDEX_OFFSET 0
2057#endif
2058
2059static int perf_counter_index(struct perf_counter *counter)
2060{
2061 if (counter->state != PERF_COUNTER_STATE_ACTIVE)
2062 return 0;
2063
2064 return counter->hw.idx + 1 - PERF_COUNTER_INDEX_OFFSET;
2065}
2066
2067/*
2068 * Callers need to ensure there can be no nesting of this function, otherwise
2069 * the seqlock logic goes bad. We can not serialize this because the arch
2070 * code calls this from NMI context.
2071 */
2072void perf_counter_update_userpage(struct perf_counter *counter)
2073{
2074 struct perf_counter_mmap_page *userpg;
2075 struct perf_mmap_data *data;
2076
2077 rcu_read_lock();
2078 data = rcu_dereference(counter->data);
2079 if (!data)
2080 goto unlock;
2081
2082 userpg = data->user_page;
2083
2084 /*
2085 * Disable preemption so as to not let the corresponding user-space
2086 * spin too long if we get preempted.
2087 */
2088 preempt_disable();
2089 ++userpg->lock;
2090 barrier();
2091 userpg->index = perf_counter_index(counter);
2092 userpg->offset = atomic64_read(&counter->count);
2093 if (counter->state == PERF_COUNTER_STATE_ACTIVE)
2094 userpg->offset -= atomic64_read(&counter->hw.prev_count);
2095
2096 userpg->time_enabled = counter->total_time_enabled +
2097 atomic64_read(&counter->child_total_time_enabled);
2098
2099 userpg->time_running = counter->total_time_running +
2100 atomic64_read(&counter->child_total_time_running);
2101
2102 barrier();
2103 ++userpg->lock;
2104 preempt_enable();
2105unlock:
2106 rcu_read_unlock();
2107}
2108
2109static int perf_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
2110{
2111 struct perf_counter *counter = vma->vm_file->private_data;
2112 struct perf_mmap_data *data;
2113 int ret = VM_FAULT_SIGBUS;
2114
2115 if (vmf->flags & FAULT_FLAG_MKWRITE) {
2116 if (vmf->pgoff == 0)
2117 ret = 0;
2118 return ret;
2119 }
2120
2121 rcu_read_lock();
2122 data = rcu_dereference(counter->data);
2123 if (!data)
2124 goto unlock;
2125
2126 if (vmf->pgoff == 0) {
2127 vmf->page = virt_to_page(data->user_page);
2128 } else {
2129 int nr = vmf->pgoff - 1;
2130
2131 if ((unsigned)nr > data->nr_pages)
2132 goto unlock;
2133
2134 if (vmf->flags & FAULT_FLAG_WRITE)
2135 goto unlock;
2136
2137 vmf->page = virt_to_page(data->data_pages[nr]);
2138 }
2139
2140 get_page(vmf->page);
2141 vmf->page->mapping = vma->vm_file->f_mapping;
2142 vmf->page->index = vmf->pgoff;
2143
2144 ret = 0;
2145unlock:
2146 rcu_read_unlock();
2147
2148 return ret;
2149}
2150
2151static int perf_mmap_data_alloc(struct perf_counter *counter, int nr_pages)
2152{
2153 struct perf_mmap_data *data;
2154 unsigned long size;
2155 int i;
2156
2157 WARN_ON(atomic_read(&counter->mmap_count));
2158
2159 size = sizeof(struct perf_mmap_data);
2160 size += nr_pages * sizeof(void *);
2161
2162 data = kzalloc(size, GFP_KERNEL);
2163 if (!data)
2164 goto fail;
2165
2166 data->user_page = (void *)get_zeroed_page(GFP_KERNEL);
2167 if (!data->user_page)
2168 goto fail_user_page;
2169
2170 for (i = 0; i < nr_pages; i++) {
2171 data->data_pages[i] = (void *)get_zeroed_page(GFP_KERNEL);
2172 if (!data->data_pages[i])
2173 goto fail_data_pages;
2174 }
2175
2176 data->nr_pages = nr_pages;
2177 atomic_set(&data->lock, -1);
2178
2179 rcu_assign_pointer(counter->data, data);
2180
2181 return 0;
2182
2183fail_data_pages:
2184 for (i--; i >= 0; i--)
2185 free_page((unsigned long)data->data_pages[i]);
2186
2187 free_page((unsigned long)data->user_page);
2188
2189fail_user_page:
2190 kfree(data);
2191
2192fail:
2193 return -ENOMEM;
2194}
2195
2196static void perf_mmap_free_page(unsigned long addr)
2197{
2198 struct page *page = virt_to_page((void *)addr);
2199
2200 page->mapping = NULL;
2201 __free_page(page);
2202}
2203
2204static void __perf_mmap_data_free(struct rcu_head *rcu_head)
2205{
2206 struct perf_mmap_data *data;
2207 int i;
2208
2209 data = container_of(rcu_head, struct perf_mmap_data, rcu_head);
2210
2211 perf_mmap_free_page((unsigned long)data->user_page);
2212 for (i = 0; i < data->nr_pages; i++)
2213 perf_mmap_free_page((unsigned long)data->data_pages[i]);
2214
2215 kfree(data);
2216}
2217
2218static void perf_mmap_data_free(struct perf_counter *counter)
2219{
2220 struct perf_mmap_data *data = counter->data;
2221
2222 WARN_ON(atomic_read(&counter->mmap_count));
2223
2224 rcu_assign_pointer(counter->data, NULL);
2225 call_rcu(&data->rcu_head, __perf_mmap_data_free);
2226}
2227
2228static void perf_mmap_open(struct vm_area_struct *vma)
2229{
2230 struct perf_counter *counter = vma->vm_file->private_data;
2231
2232 atomic_inc(&counter->mmap_count);
2233}
2234
2235static void perf_mmap_close(struct vm_area_struct *vma)
2236{
2237 struct perf_counter *counter = vma->vm_file->private_data;
2238
2239 WARN_ON_ONCE(counter->ctx->parent_ctx);
2240 if (atomic_dec_and_mutex_lock(&counter->mmap_count, &counter->mmap_mutex)) {
2241 struct user_struct *user = current_user();
2242
2243 atomic_long_sub(counter->data->nr_pages + 1, &user->locked_vm);
2244 vma->vm_mm->locked_vm -= counter->data->nr_locked;
2245 perf_mmap_data_free(counter);
2246 mutex_unlock(&counter->mmap_mutex);
2247 }
2248}
2249
2250static struct vm_operations_struct perf_mmap_vmops = {
2251 .open = perf_mmap_open,
2252 .close = perf_mmap_close,
2253 .fault = perf_mmap_fault,
2254 .page_mkwrite = perf_mmap_fault,
2255};
2256
2257static int perf_mmap(struct file *file, struct vm_area_struct *vma)
2258{
2259 struct perf_counter *counter = file->private_data;
2260 unsigned long user_locked, user_lock_limit;
2261 struct user_struct *user = current_user();
2262 unsigned long locked, lock_limit;
2263 unsigned long vma_size;
2264 unsigned long nr_pages;
2265 long user_extra, extra;
2266 int ret = 0;
2267
2268 if (!(vma->vm_flags & VM_SHARED))
2269 return -EINVAL;
2270
2271 vma_size = vma->vm_end - vma->vm_start;
2272 nr_pages = (vma_size / PAGE_SIZE) - 1;
2273
2274 /*
2275 * If we have data pages ensure they're a power-of-two number, so we
2276 * can do bitmasks instead of modulo.
2277 */
2278 if (nr_pages != 0 && !is_power_of_2(nr_pages))
2279 return -EINVAL;
2280
2281 if (vma_size != PAGE_SIZE * (1 + nr_pages))
2282 return -EINVAL;
2283
2284 if (vma->vm_pgoff != 0)
2285 return -EINVAL;
2286
2287 WARN_ON_ONCE(counter->ctx->parent_ctx);
2288 mutex_lock(&counter->mmap_mutex);
2289 if (counter->output) {
2290 ret = -EINVAL;
2291 goto unlock;
2292 }
2293
2294 if (atomic_inc_not_zero(&counter->mmap_count)) {
2295 if (nr_pages != counter->data->nr_pages)
2296 ret = -EINVAL;
2297 goto unlock;
2298 }
2299
2300 user_extra = nr_pages + 1;
2301 user_lock_limit = sysctl_perf_counter_mlock >> (PAGE_SHIFT - 10);
2302
2303 /*
2304 * Increase the limit linearly with more CPUs:
2305 */
2306 user_lock_limit *= num_online_cpus();
2307
2308 user_locked = atomic_long_read(&user->locked_vm) + user_extra;
2309
2310 extra = 0;
2311 if (user_locked > user_lock_limit)
2312 extra = user_locked - user_lock_limit;
2313
2314 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
2315 lock_limit >>= PAGE_SHIFT;
2316 locked = vma->vm_mm->locked_vm + extra;
2317
2318 if ((locked > lock_limit) && !capable(CAP_IPC_LOCK)) {
2319 ret = -EPERM;
2320 goto unlock;
2321 }
2322
2323 WARN_ON(counter->data);
2324 ret = perf_mmap_data_alloc(counter, nr_pages);
2325 if (ret)
2326 goto unlock;
2327
2328 atomic_set(&counter->mmap_count, 1);
2329 atomic_long_add(user_extra, &user->locked_vm);
2330 vma->vm_mm->locked_vm += extra;
2331 counter->data->nr_locked = extra;
2332 if (vma->vm_flags & VM_WRITE)
2333 counter->data->writable = 1;
2334
2335unlock:
2336 mutex_unlock(&counter->mmap_mutex);
2337
2338 vma->vm_flags |= VM_RESERVED;
2339 vma->vm_ops = &perf_mmap_vmops;
2340
2341 return ret;
2342}
2343
2344static int perf_fasync(int fd, struct file *filp, int on)
2345{
2346 struct inode *inode = filp->f_path.dentry->d_inode;
2347 struct perf_counter *counter = filp->private_data;
2348 int retval;
2349
2350 mutex_lock(&inode->i_mutex);
2351 retval = fasync_helper(fd, filp, on, &counter->fasync);
2352 mutex_unlock(&inode->i_mutex);
2353
2354 if (retval < 0)
2355 return retval;
2356
2357 return 0;
2358}
2359
2360static const struct file_operations perf_fops = {
2361 .release = perf_release,
2362 .read = perf_read,
2363 .poll = perf_poll,
2364 .unlocked_ioctl = perf_ioctl,
2365 .compat_ioctl = perf_ioctl,
2366 .mmap = perf_mmap,
2367 .fasync = perf_fasync,
2368};
2369
2370/*
2371 * Perf counter wakeup
2372 *
2373 * If there's data, ensure we set the poll() state and publish everything
2374 * to user-space before waking everybody up.
2375 */
2376
2377void perf_counter_wakeup(struct perf_counter *counter)
2378{
2379 wake_up_all(&counter->waitq);
2380
2381 if (counter->pending_kill) {
2382 kill_fasync(&counter->fasync, SIGIO, counter->pending_kill);
2383 counter->pending_kill = 0;
2384 }
2385}
2386
2387/*
2388 * Pending wakeups
2389 *
2390 * Handle the case where we need to wakeup up from NMI (or rq->lock) context.
2391 *
2392 * The NMI bit means we cannot possibly take locks. Therefore, maintain a
2393 * single linked list and use cmpxchg() to add entries lockless.
2394 */
2395
2396static void perf_pending_counter(struct perf_pending_entry *entry)
2397{
2398 struct perf_counter *counter = container_of(entry,
2399 struct perf_counter, pending);
2400
2401 if (counter->pending_disable) {
2402 counter->pending_disable = 0;
2403 __perf_counter_disable(counter);
2404 }
2405
2406 if (counter->pending_wakeup) {
2407 counter->pending_wakeup = 0;
2408 perf_counter_wakeup(counter);
2409 }
2410}
2411
2412#define PENDING_TAIL ((struct perf_pending_entry *)-1UL)
2413
2414static DEFINE_PER_CPU(struct perf_pending_entry *, perf_pending_head) = {
2415 PENDING_TAIL,
2416};
2417
2418static void perf_pending_queue(struct perf_pending_entry *entry,
2419 void (*func)(struct perf_pending_entry *))
2420{
2421 struct perf_pending_entry **head;
2422
2423 if (cmpxchg(&entry->next, NULL, PENDING_TAIL) != NULL)
2424 return;
2425
2426 entry->func = func;
2427
2428 head = &get_cpu_var(perf_pending_head);
2429
2430 do {
2431 entry->next = *head;
2432 } while (cmpxchg(head, entry->next, entry) != entry->next);
2433
2434 set_perf_counter_pending();
2435
2436 put_cpu_var(perf_pending_head);
2437}
2438
2439static int __perf_pending_run(void)
2440{
2441 struct perf_pending_entry *list;
2442 int nr = 0;
2443
2444 list = xchg(&__get_cpu_var(perf_pending_head), PENDING_TAIL);
2445 while (list != PENDING_TAIL) {
2446 void (*func)(struct perf_pending_entry *);
2447 struct perf_pending_entry *entry = list;
2448
2449 list = list->next;
2450
2451 func = entry->func;
2452 entry->next = NULL;
2453 /*
2454 * Ensure we observe the unqueue before we issue the wakeup,
2455 * so that we won't be waiting forever.
2456 * -- see perf_not_pending().
2457 */
2458 smp_wmb();
2459
2460 func(entry);
2461 nr++;
2462 }
2463
2464 return nr;
2465}
2466
2467static inline int perf_not_pending(struct perf_counter *counter)
2468{
2469 /*
2470 * If we flush on whatever cpu we run, there is a chance we don't
2471 * need to wait.
2472 */
2473 get_cpu();
2474 __perf_pending_run();
2475 put_cpu();
2476
2477 /*
2478 * Ensure we see the proper queue state before going to sleep
2479 * so that we do not miss the wakeup. -- see perf_pending_handle()
2480 */
2481 smp_rmb();
2482 return counter->pending.next == NULL;
2483}
2484
2485static void perf_pending_sync(struct perf_counter *counter)
2486{
2487 wait_event(counter->waitq, perf_not_pending(counter));
2488}
2489
2490void perf_counter_do_pending(void)
2491{
2492 __perf_pending_run();
2493}
2494
2495/*
2496 * Callchain support -- arch specific
2497 */
2498
2499__weak struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
2500{
2501 return NULL;
2502}
2503
2504/*
2505 * Output
2506 */
2507
2508struct perf_output_handle {
2509 struct perf_counter *counter;
2510 struct perf_mmap_data *data;
2511 unsigned long head;
2512 unsigned long offset;
2513 int nmi;
2514 int sample;
2515 int locked;
2516 unsigned long flags;
2517};
2518
2519static bool perf_output_space(struct perf_mmap_data *data,
2520 unsigned int offset, unsigned int head)
2521{
2522 unsigned long tail;
2523 unsigned long mask;
2524
2525 if (!data->writable)
2526 return true;
2527
2528 mask = (data->nr_pages << PAGE_SHIFT) - 1;
2529 /*
2530 * Userspace could choose to issue a mb() before updating the tail
2531 * pointer. So that all reads will be completed before the write is
2532 * issued.
2533 */
2534 tail = ACCESS_ONCE(data->user_page->data_tail);
2535 smp_rmb();
2536
2537 offset = (offset - tail) & mask;
2538 head = (head - tail) & mask;
2539
2540 if ((int)(head - offset) < 0)
2541 return false;
2542
2543 return true;
2544}
2545
2546static void perf_output_wakeup(struct perf_output_handle *handle)
2547{
2548 atomic_set(&handle->data->poll, POLL_IN);
2549
2550 if (handle->nmi) {
2551 handle->counter->pending_wakeup = 1;
2552 perf_pending_queue(&handle->counter->pending,
2553 perf_pending_counter);
2554 } else
2555 perf_counter_wakeup(handle->counter);
2556}
2557
2558/*
2559 * Curious locking construct.
2560 *
2561 * We need to ensure a later event doesn't publish a head when a former
2562 * event isn't done writing. However since we need to deal with NMIs we
2563 * cannot fully serialize things.
2564 *
2565 * What we do is serialize between CPUs so we only have to deal with NMI
2566 * nesting on a single CPU.
2567 *
2568 * We only publish the head (and generate a wakeup) when the outer-most
2569 * event completes.
2570 */
2571static void perf_output_lock(struct perf_output_handle *handle)
2572{
2573 struct perf_mmap_data *data = handle->data;
2574 int cpu;
2575
2576 handle->locked = 0;
2577
2578 local_irq_save(handle->flags);
2579 cpu = smp_processor_id();
2580
2581 if (in_nmi() && atomic_read(&data->lock) == cpu)
2582 return;
2583
2584 while (atomic_cmpxchg(&data->lock, -1, cpu) != -1)
2585 cpu_relax();
2586
2587 handle->locked = 1;
2588}
2589
2590static void perf_output_unlock(struct perf_output_handle *handle)
2591{
2592 struct perf_mmap_data *data = handle->data;
2593 unsigned long head;
2594 int cpu;
2595
2596 data->done_head = data->head;
2597
2598 if (!handle->locked)
2599 goto out;
2600
2601again:
2602 /*
2603 * The xchg implies a full barrier that ensures all writes are done
2604 * before we publish the new head, matched by a rmb() in userspace when
2605 * reading this position.
2606 */
2607 while ((head = atomic_long_xchg(&data->done_head, 0)))
2608 data->user_page->data_head = head;
2609
2610 /*
2611 * NMI can happen here, which means we can miss a done_head update.
2612 */
2613
2614 cpu = atomic_xchg(&data->lock, -1);
2615 WARN_ON_ONCE(cpu != smp_processor_id());
2616
2617 /*
2618 * Therefore we have to validate we did not indeed do so.
2619 */
2620 if (unlikely(atomic_long_read(&data->done_head))) {
2621 /*
2622 * Since we had it locked, we can lock it again.
2623 */
2624 while (atomic_cmpxchg(&data->lock, -1, cpu) != -1)
2625 cpu_relax();
2626
2627 goto again;
2628 }
2629
2630 if (atomic_xchg(&data->wakeup, 0))
2631 perf_output_wakeup(handle);
2632out:
2633 local_irq_restore(handle->flags);
2634}
2635
2636static void perf_output_copy(struct perf_output_handle *handle,
2637 const void *buf, unsigned int len)
2638{
2639 unsigned int pages_mask;
2640 unsigned int offset;
2641 unsigned int size;
2642 void **pages;
2643
2644 offset = handle->offset;
2645 pages_mask = handle->data->nr_pages - 1;
2646 pages = handle->data->data_pages;
2647
2648 do {
2649 unsigned int page_offset;
2650 int nr;
2651
2652 nr = (offset >> PAGE_SHIFT) & pages_mask;
2653 page_offset = offset & (PAGE_SIZE - 1);
2654 size = min_t(unsigned int, PAGE_SIZE - page_offset, len);
2655
2656 memcpy(pages[nr] + page_offset, buf, size);
2657
2658 len -= size;
2659 buf += size;
2660 offset += size;
2661 } while (len);
2662
2663 handle->offset = offset;
2664
2665 /*
2666 * Check we didn't copy past our reservation window, taking the
2667 * possible unsigned int wrap into account.
2668 */
2669 WARN_ON_ONCE(((long)(handle->head - handle->offset)) < 0);
2670}
2671
2672#define perf_output_put(handle, x) \
2673 perf_output_copy((handle), &(x), sizeof(x))
2674
2675static int perf_output_begin(struct perf_output_handle *handle,
2676 struct perf_counter *counter, unsigned int size,
2677 int nmi, int sample)
2678{
2679 struct perf_counter *output_counter;
2680 struct perf_mmap_data *data;
2681 unsigned int offset, head;
2682 int have_lost;
2683 struct {
2684 struct perf_event_header header;
2685 u64 id;
2686 u64 lost;
2687 } lost_event;
2688
2689 rcu_read_lock();
2690 /*
2691 * For inherited counters we send all the output towards the parent.
2692 */
2693 if (counter->parent)
2694 counter = counter->parent;
2695
2696 output_counter = rcu_dereference(counter->output);
2697 if (output_counter)
2698 counter = output_counter;
2699
2700 data = rcu_dereference(counter->data);
2701 if (!data)
2702 goto out;
2703
2704 handle->data = data;
2705 handle->counter = counter;
2706 handle->nmi = nmi;
2707 handle->sample = sample;
2708
2709 if (!data->nr_pages)
2710 goto fail;
2711
2712 have_lost = atomic_read(&data->lost);
2713 if (have_lost)
2714 size += sizeof(lost_event);
2715
2716 perf_output_lock(handle);
2717
2718 do {
2719 offset = head = atomic_long_read(&data->head);
2720 head += size;
2721 if (unlikely(!perf_output_space(data, offset, head)))
2722 goto fail;
2723 } while (atomic_long_cmpxchg(&data->head, offset, head) != offset);
2724
2725 handle->offset = offset;
2726 handle->head = head;
2727
2728 if ((offset >> PAGE_SHIFT) != (head >> PAGE_SHIFT))
2729 atomic_set(&data->wakeup, 1);
2730
2731 if (have_lost) {
2732 lost_event.header.type = PERF_EVENT_LOST;
2733 lost_event.header.misc = 0;
2734 lost_event.header.size = sizeof(lost_event);
2735 lost_event.id = counter->id;
2736 lost_event.lost = atomic_xchg(&data->lost, 0);
2737
2738 perf_output_put(handle, lost_event);
2739 }
2740
2741 return 0;
2742
2743fail:
2744 atomic_inc(&data->lost);
2745 perf_output_unlock(handle);
2746out:
2747 rcu_read_unlock();
2748
2749 return -ENOSPC;
2750}
2751
2752static void perf_output_end(struct perf_output_handle *handle)
2753{
2754 struct perf_counter *counter = handle->counter;
2755 struct perf_mmap_data *data = handle->data;
2756
2757 int wakeup_events = counter->attr.wakeup_events;
2758
2759 if (handle->sample && wakeup_events) {
2760 int events = atomic_inc_return(&data->events);
2761 if (events >= wakeup_events) {
2762 atomic_sub(wakeup_events, &data->events);
2763 atomic_set(&data->wakeup, 1);
2764 }
2765 }
2766
2767 perf_output_unlock(handle);
2768 rcu_read_unlock();
2769}
2770
2771static u32 perf_counter_pid(struct perf_counter *counter, struct task_struct *p)
2772{
2773 /*
2774 * only top level counters have the pid namespace they were created in
2775 */
2776 if (counter->parent)
2777 counter = counter->parent;
2778
2779 return task_tgid_nr_ns(p, counter->ns);
2780}
2781
2782static u32 perf_counter_tid(struct perf_counter *counter, struct task_struct *p)
2783{
2784 /*
2785 * only top level counters have the pid namespace they were created in
2786 */
2787 if (counter->parent)
2788 counter = counter->parent;
2789
2790 return task_pid_nr_ns(p, counter->ns);
2791}
2792
2793static void perf_output_read_one(struct perf_output_handle *handle,
2794 struct perf_counter *counter)
2795{
2796 u64 read_format = counter->attr.read_format;
2797 u64 values[4];
2798 int n = 0;
2799
2800 values[n++] = atomic64_read(&counter->count);
2801 if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
2802 values[n++] = counter->total_time_enabled +
2803 atomic64_read(&counter->child_total_time_enabled);
2804 }
2805 if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
2806 values[n++] = counter->total_time_running +
2807 atomic64_read(&counter->child_total_time_running);
2808 }
2809 if (read_format & PERF_FORMAT_ID)
2810 values[n++] = primary_counter_id(counter);
2811
2812 perf_output_copy(handle, values, n * sizeof(u64));
2813}
2814
2815/*
2816 * XXX PERF_FORMAT_GROUP vs inherited counters seems difficult.
2817 */
2818static void perf_output_read_group(struct perf_output_handle *handle,
2819 struct perf_counter *counter)
2820{
2821 struct perf_counter *leader = counter->group_leader, *sub;
2822 u64 read_format = counter->attr.read_format;
2823 u64 values[5];
2824 int n = 0;
2825
2826 values[n++] = 1 + leader->nr_siblings;
2827
2828 if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
2829 values[n++] = leader->total_time_enabled;
2830
2831 if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
2832 values[n++] = leader->total_time_running;
2833
2834 if (leader != counter)
2835 leader->pmu->read(leader);
2836
2837 values[n++] = atomic64_read(&leader->count);
2838 if (read_format & PERF_FORMAT_ID)
2839 values[n++] = primary_counter_id(leader);
2840
2841 perf_output_copy(handle, values, n * sizeof(u64));
2842
2843 list_for_each_entry(sub, &leader->sibling_list, list_entry) {
2844 n = 0;
2845
2846 if (sub != counter)
2847 sub->pmu->read(sub);
2848
2849 values[n++] = atomic64_read(&sub->count);
2850 if (read_format & PERF_FORMAT_ID)
2851 values[n++] = primary_counter_id(sub);
2852
2853 perf_output_copy(handle, values, n * sizeof(u64));
2854 }
2855}
2856
2857static void perf_output_read(struct perf_output_handle *handle,
2858 struct perf_counter *counter)
2859{
2860 if (counter->attr.read_format & PERF_FORMAT_GROUP)
2861 perf_output_read_group(handle, counter);
2862 else
2863 perf_output_read_one(handle, counter);
2864}
2865
2866void perf_counter_output(struct perf_counter *counter, int nmi,
2867 struct perf_sample_data *data)
2868{
2869 int ret;
2870 u64 sample_type = counter->attr.sample_type;
2871 struct perf_output_handle handle;
2872 struct perf_event_header header;
2873 u64 ip;
2874 struct {
2875 u32 pid, tid;
2876 } tid_entry;
2877 struct perf_callchain_entry *callchain = NULL;
2878 int callchain_size = 0;
2879 u64 time;
2880 struct {
2881 u32 cpu, reserved;
2882 } cpu_entry;
2883
2884 header.type = PERF_EVENT_SAMPLE;
2885 header.size = sizeof(header);
2886
2887 header.misc = 0;
2888 header.misc |= perf_misc_flags(data->regs);
2889
2890 if (sample_type & PERF_SAMPLE_IP) {
2891 ip = perf_instruction_pointer(data->regs);
2892 header.size += sizeof(ip);
2893 }
2894
2895 if (sample_type & PERF_SAMPLE_TID) {
2896 /* namespace issues */
2897 tid_entry.pid = perf_counter_pid(counter, current);
2898 tid_entry.tid = perf_counter_tid(counter, current);
2899
2900 header.size += sizeof(tid_entry);
2901 }
2902
2903 if (sample_type & PERF_SAMPLE_TIME) {
2904 /*
2905 * Maybe do better on x86 and provide cpu_clock_nmi()
2906 */
2907 time = sched_clock();
2908
2909 header.size += sizeof(u64);
2910 }
2911
2912 if (sample_type & PERF_SAMPLE_ADDR)
2913 header.size += sizeof(u64);
2914
2915 if (sample_type & PERF_SAMPLE_ID)
2916 header.size += sizeof(u64);
2917
2918 if (sample_type & PERF_SAMPLE_STREAM_ID)
2919 header.size += sizeof(u64);
2920
2921 if (sample_type & PERF_SAMPLE_CPU) {
2922 header.size += sizeof(cpu_entry);
2923
2924 cpu_entry.cpu = raw_smp_processor_id();
2925 cpu_entry.reserved = 0;
2926 }
2927
2928 if (sample_type & PERF_SAMPLE_PERIOD)
2929 header.size += sizeof(u64);
2930
2931 if (sample_type & PERF_SAMPLE_READ)
2932 header.size += perf_counter_read_size(counter);
2933
2934 if (sample_type & PERF_SAMPLE_CALLCHAIN) {
2935 callchain = perf_callchain(data->regs);
2936
2937 if (callchain) {
2938 callchain_size = (1 + callchain->nr) * sizeof(u64);
2939 header.size += callchain_size;
2940 } else
2941 header.size += sizeof(u64);
2942 }
2943
2944 if (sample_type & PERF_SAMPLE_RAW) {
2945 int size = sizeof(u32);
2946
2947 if (data->raw)
2948 size += data->raw->size;
2949 else
2950 size += sizeof(u32);
2951
2952 WARN_ON_ONCE(size & (sizeof(u64)-1));
2953 header.size += size;
2954 }
2955
2956 ret = perf_output_begin(&handle, counter, header.size, nmi, 1);
2957 if (ret)
2958 return;
2959
2960 perf_output_put(&handle, header);
2961
2962 if (sample_type & PERF_SAMPLE_IP)
2963 perf_output_put(&handle, ip);
2964
2965 if (sample_type & PERF_SAMPLE_TID)
2966 perf_output_put(&handle, tid_entry);
2967
2968 if (sample_type & PERF_SAMPLE_TIME)
2969 perf_output_put(&handle, time);
2970
2971 if (sample_type & PERF_SAMPLE_ADDR)
2972 perf_output_put(&handle, data->addr);
2973
2974 if (sample_type & PERF_SAMPLE_ID) {
2975 u64 id = primary_counter_id(counter);
2976
2977 perf_output_put(&handle, id);
2978 }
2979
2980 if (sample_type & PERF_SAMPLE_STREAM_ID)
2981 perf_output_put(&handle, counter->id);
2982
2983 if (sample_type & PERF_SAMPLE_CPU)
2984 perf_output_put(&handle, cpu_entry);
2985
2986 if (sample_type & PERF_SAMPLE_PERIOD)
2987 perf_output_put(&handle, data->period);
2988
2989 if (sample_type & PERF_SAMPLE_READ)
2990 perf_output_read(&handle, counter);
2991
2992 if (sample_type & PERF_SAMPLE_CALLCHAIN) {
2993 if (callchain)
2994 perf_output_copy(&handle, callchain, callchain_size);
2995 else {
2996 u64 nr = 0;
2997 perf_output_put(&handle, nr);
2998 }
2999 }
3000
3001 if (sample_type & PERF_SAMPLE_RAW) {
3002 if (data->raw) {
3003 perf_output_put(&handle, data->raw->size);
3004 perf_output_copy(&handle, data->raw->data, data->raw->size);
3005 } else {
3006 struct {
3007 u32 size;
3008 u32 data;
3009 } raw = {
3010 .size = sizeof(u32),
3011 .data = 0,
3012 };
3013 perf_output_put(&handle, raw);
3014 }
3015 }
3016
3017 perf_output_end(&handle);
3018}
3019
3020/*
3021 * read event
3022 */
3023
3024struct perf_read_event {
3025 struct perf_event_header header;
3026
3027 u32 pid;
3028 u32 tid;
3029};
3030
3031static void
3032perf_counter_read_event(struct perf_counter *counter,
3033 struct task_struct *task)
3034{
3035 struct perf_output_handle handle;
3036 struct perf_read_event event = {
3037 .header = {
3038 .type = PERF_EVENT_READ,
3039 .misc = 0,
3040 .size = sizeof(event) + perf_counter_read_size(counter),
3041 },
3042 .pid = perf_counter_pid(counter, task),
3043 .tid = perf_counter_tid(counter, task),
3044 };
3045 int ret;
3046
3047 ret = perf_output_begin(&handle, counter, event.header.size, 0, 0);
3048 if (ret)
3049 return;
3050
3051 perf_output_put(&handle, event);
3052 perf_output_read(&handle, counter);
3053
3054 perf_output_end(&handle);
3055}
3056
3057/*
3058 * task tracking -- fork/exit
3059 *
3060 * enabled by: attr.comm | attr.mmap | attr.task
3061 */
3062
3063struct perf_task_event {
3064 struct task_struct *task;
3065 struct perf_counter_context *task_ctx;
3066
3067 struct {
3068 struct perf_event_header header;
3069
3070 u32 pid;
3071 u32 ppid;
3072 u32 tid;
3073 u32 ptid;
3074 } event;
3075};
3076
3077static void perf_counter_task_output(struct perf_counter *counter,
3078 struct perf_task_event *task_event)
3079{
3080 struct perf_output_handle handle;
3081 int size = task_event->event.header.size;
3082 struct task_struct *task = task_event->task;
3083 int ret = perf_output_begin(&handle, counter, size, 0, 0);
3084
3085 if (ret)
3086 return;
3087
3088 task_event->event.pid = perf_counter_pid(counter, task);
3089 task_event->event.ppid = perf_counter_pid(counter, current);
3090
3091 task_event->event.tid = perf_counter_tid(counter, task);
3092 task_event->event.ptid = perf_counter_tid(counter, current);
3093
3094 perf_output_put(&handle, task_event->event);
3095 perf_output_end(&handle);
3096}
3097
3098static int perf_counter_task_match(struct perf_counter *counter)
3099{
3100 if (counter->attr.comm || counter->attr.mmap || counter->attr.task)
3101 return 1;
3102
3103 return 0;
3104}
3105
3106static void perf_counter_task_ctx(struct perf_counter_context *ctx,
3107 struct perf_task_event *task_event)
3108{
3109 struct perf_counter *counter;
3110
3111 if (system_state != SYSTEM_RUNNING || list_empty(&ctx->event_list))
3112 return;
3113
3114 rcu_read_lock();
3115 list_for_each_entry_rcu(counter, &ctx->event_list, event_entry) {
3116 if (perf_counter_task_match(counter))
3117 perf_counter_task_output(counter, task_event);
3118 }
3119 rcu_read_unlock();
3120}
3121
3122static void perf_counter_task_event(struct perf_task_event *task_event)
3123{
3124 struct perf_cpu_context *cpuctx;
3125 struct perf_counter_context *ctx = task_event->task_ctx;
3126
3127 cpuctx = &get_cpu_var(perf_cpu_context);
3128 perf_counter_task_ctx(&cpuctx->ctx, task_event);
3129 put_cpu_var(perf_cpu_context);
3130
3131 rcu_read_lock();
3132 if (!ctx)
3133 ctx = rcu_dereference(task_event->task->perf_counter_ctxp);
3134 if (ctx)
3135 perf_counter_task_ctx(ctx, task_event);
3136 rcu_read_unlock();
3137}
3138
3139static void perf_counter_task(struct task_struct *task,
3140 struct perf_counter_context *task_ctx,
3141 int new)
3142{
3143 struct perf_task_event task_event;
3144
3145 if (!atomic_read(&nr_comm_counters) &&
3146 !atomic_read(&nr_mmap_counters) &&
3147 !atomic_read(&nr_task_counters))
3148 return;
3149
3150 task_event = (struct perf_task_event){
3151 .task = task,
3152 .task_ctx = task_ctx,
3153 .event = {
3154 .header = {
3155 .type = new ? PERF_EVENT_FORK : PERF_EVENT_EXIT,
3156 .misc = 0,
3157 .size = sizeof(task_event.event),
3158 },
3159 /* .pid */
3160 /* .ppid */
3161 /* .tid */
3162 /* .ptid */
3163 },
3164 };
3165
3166 perf_counter_task_event(&task_event);
3167}
3168
3169void perf_counter_fork(struct task_struct *task)
3170{
3171 perf_counter_task(task, NULL, 1);
3172}
3173
3174/*
3175 * comm tracking
3176 */
3177
3178struct perf_comm_event {
3179 struct task_struct *task;
3180 char *comm;
3181 int comm_size;
3182
3183 struct {
3184 struct perf_event_header header;
3185
3186 u32 pid;
3187 u32 tid;
3188 } event;
3189};
3190
3191static void perf_counter_comm_output(struct perf_counter *counter,
3192 struct perf_comm_event *comm_event)
3193{
3194 struct perf_output_handle handle;
3195 int size = comm_event->event.header.size;
3196 int ret = perf_output_begin(&handle, counter, size, 0, 0);
3197
3198 if (ret)
3199 return;
3200
3201 comm_event->event.pid = perf_counter_pid(counter, comm_event->task);
3202 comm_event->event.tid = perf_counter_tid(counter, comm_event->task);
3203
3204 perf_output_put(&handle, comm_event->event);
3205 perf_output_copy(&handle, comm_event->comm,
3206 comm_event->comm_size);
3207 perf_output_end(&handle);
3208}
3209
3210static int perf_counter_comm_match(struct perf_counter *counter)
3211{
3212 if (counter->attr.comm)
3213 return 1;
3214
3215 return 0;
3216}
3217
3218static void perf_counter_comm_ctx(struct perf_counter_context *ctx,
3219 struct perf_comm_event *comm_event)
3220{
3221 struct perf_counter *counter;
3222
3223 if (system_state != SYSTEM_RUNNING || list_empty(&ctx->event_list))
3224 return;
3225
3226 rcu_read_lock();
3227 list_for_each_entry_rcu(counter, &ctx->event_list, event_entry) {
3228 if (perf_counter_comm_match(counter))
3229 perf_counter_comm_output(counter, comm_event);
3230 }
3231 rcu_read_unlock();
3232}
3233
3234static void perf_counter_comm_event(struct perf_comm_event *comm_event)
3235{
3236 struct perf_cpu_context *cpuctx;
3237 struct perf_counter_context *ctx;
3238 unsigned int size;
3239 char comm[TASK_COMM_LEN];
3240
3241 memset(comm, 0, sizeof(comm));
3242 strncpy(comm, comm_event->task->comm, sizeof(comm));
3243 size = ALIGN(strlen(comm)+1, sizeof(u64));
3244
3245 comm_event->comm = comm;
3246 comm_event->comm_size = size;
3247
3248 comm_event->event.header.size = sizeof(comm_event->event) + size;
3249
3250 cpuctx = &get_cpu_var(perf_cpu_context);
3251 perf_counter_comm_ctx(&cpuctx->ctx, comm_event);
3252 put_cpu_var(perf_cpu_context);
3253
3254 rcu_read_lock();
3255 /*
3256 * doesn't really matter which of the child contexts the
3257 * events ends up in.
3258 */
3259 ctx = rcu_dereference(current->perf_counter_ctxp);
3260 if (ctx)
3261 perf_counter_comm_ctx(ctx, comm_event);
3262 rcu_read_unlock();
3263}
3264
3265void perf_counter_comm(struct task_struct *task)
3266{
3267 struct perf_comm_event comm_event;
3268
3269 if (task->perf_counter_ctxp)
3270 perf_counter_enable_on_exec(task);
3271
3272 if (!atomic_read(&nr_comm_counters))
3273 return;
3274
3275 comm_event = (struct perf_comm_event){
3276 .task = task,
3277 /* .comm */
3278 /* .comm_size */
3279 .event = {
3280 .header = {
3281 .type = PERF_EVENT_COMM,
3282 .misc = 0,
3283 /* .size */
3284 },
3285 /* .pid */
3286 /* .tid */
3287 },
3288 };
3289
3290 perf_counter_comm_event(&comm_event);
3291}
3292
3293/*
3294 * mmap tracking
3295 */
3296
3297struct perf_mmap_event {
3298 struct vm_area_struct *vma;
3299
3300 const char *file_name;
3301 int file_size;
3302
3303 struct {
3304 struct perf_event_header header;
3305
3306 u32 pid;
3307 u32 tid;
3308 u64 start;
3309 u64 len;
3310 u64 pgoff;
3311 } event;
3312};
3313
3314static void perf_counter_mmap_output(struct perf_counter *counter,
3315 struct perf_mmap_event *mmap_event)
3316{
3317 struct perf_output_handle handle;
3318 int size = mmap_event->event.header.size;
3319 int ret = perf_output_begin(&handle, counter, size, 0, 0);
3320
3321 if (ret)
3322 return;
3323
3324 mmap_event->event.pid = perf_counter_pid(counter, current);
3325 mmap_event->event.tid = perf_counter_tid(counter, current);
3326
3327 perf_output_put(&handle, mmap_event->event);
3328 perf_output_copy(&handle, mmap_event->file_name,
3329 mmap_event->file_size);
3330 perf_output_end(&handle);
3331}
3332
3333static int perf_counter_mmap_match(struct perf_counter *counter,
3334 struct perf_mmap_event *mmap_event)
3335{
3336 if (counter->attr.mmap)
3337 return 1;
3338
3339 return 0;
3340}
3341
3342static void perf_counter_mmap_ctx(struct perf_counter_context *ctx,
3343 struct perf_mmap_event *mmap_event)
3344{
3345 struct perf_counter *counter;
3346
3347 if (system_state != SYSTEM_RUNNING || list_empty(&ctx->event_list))
3348 return;
3349
3350 rcu_read_lock();
3351 list_for_each_entry_rcu(counter, &ctx->event_list, event_entry) {
3352 if (perf_counter_mmap_match(counter, mmap_event))
3353 perf_counter_mmap_output(counter, mmap_event);
3354 }
3355 rcu_read_unlock();
3356}
3357
3358static void perf_counter_mmap_event(struct perf_mmap_event *mmap_event)
3359{
3360 struct perf_cpu_context *cpuctx;
3361 struct perf_counter_context *ctx;
3362 struct vm_area_struct *vma = mmap_event->vma;
3363 struct file *file = vma->vm_file;
3364 unsigned int size;
3365 char tmp[16];
3366 char *buf = NULL;
3367 const char *name;
3368
3369 memset(tmp, 0, sizeof(tmp));
3370
3371 if (file) {
3372 /*
3373 * d_path works from the end of the buffer backwards, so we
3374 * need to add enough zero bytes after the string to handle
3375 * the 64bit alignment we do later.
3376 */
3377 buf = kzalloc(PATH_MAX + sizeof(u64), GFP_KERNEL);
3378 if (!buf) {
3379 name = strncpy(tmp, "//enomem", sizeof(tmp));
3380 goto got_name;
3381 }
3382 name = d_path(&file->f_path, buf, PATH_MAX);
3383 if (IS_ERR(name)) {
3384 name = strncpy(tmp, "//toolong", sizeof(tmp));
3385 goto got_name;
3386 }
3387 } else {
3388 if (arch_vma_name(mmap_event->vma)) {
3389 name = strncpy(tmp, arch_vma_name(mmap_event->vma),
3390 sizeof(tmp));
3391 goto got_name;
3392 }
3393
3394 if (!vma->vm_mm) {
3395 name = strncpy(tmp, "[vdso]", sizeof(tmp));
3396 goto got_name;
3397 }
3398
3399 name = strncpy(tmp, "//anon", sizeof(tmp));
3400 goto got_name;
3401 }
3402
3403got_name:
3404 size = ALIGN(strlen(name)+1, sizeof(u64));
3405
3406 mmap_event->file_name = name;
3407 mmap_event->file_size = size;
3408
3409 mmap_event->event.header.size = sizeof(mmap_event->event) + size;
3410
3411 cpuctx = &get_cpu_var(perf_cpu_context);
3412 perf_counter_mmap_ctx(&cpuctx->ctx, mmap_event);
3413 put_cpu_var(perf_cpu_context);
3414
3415 rcu_read_lock();
3416 /*
3417 * doesn't really matter which of the child contexts the
3418 * events ends up in.
3419 */
3420 ctx = rcu_dereference(current->perf_counter_ctxp);
3421 if (ctx)
3422 perf_counter_mmap_ctx(ctx, mmap_event);
3423 rcu_read_unlock();
3424
3425 kfree(buf);
3426}
3427
3428void __perf_counter_mmap(struct vm_area_struct *vma)
3429{
3430 struct perf_mmap_event mmap_event;
3431
3432 if (!atomic_read(&nr_mmap_counters))
3433 return;
3434
3435 mmap_event = (struct perf_mmap_event){
3436 .vma = vma,
3437 /* .file_name */
3438 /* .file_size */
3439 .event = {
3440 .header = {
3441 .type = PERF_EVENT_MMAP,
3442 .misc = 0,
3443 /* .size */
3444 },
3445 /* .pid */
3446 /* .tid */
3447 .start = vma->vm_start,
3448 .len = vma->vm_end - vma->vm_start,
3449 .pgoff = vma->vm_pgoff,
3450 },
3451 };
3452
3453 perf_counter_mmap_event(&mmap_event);
3454}
3455
3456/*
3457 * IRQ throttle logging
3458 */
3459
3460static void perf_log_throttle(struct perf_counter *counter, int enable)
3461{
3462 struct perf_output_handle handle;
3463 int ret;
3464
3465 struct {
3466 struct perf_event_header header;
3467 u64 time;
3468 u64 id;
3469 u64 stream_id;
3470 } throttle_event = {
3471 .header = {
3472 .type = PERF_EVENT_THROTTLE,
3473 .misc = 0,
3474 .size = sizeof(throttle_event),
3475 },
3476 .time = sched_clock(),
3477 .id = primary_counter_id(counter),
3478 .stream_id = counter->id,
3479 };
3480
3481 if (enable)
3482 throttle_event.header.type = PERF_EVENT_UNTHROTTLE;
3483
3484 ret = perf_output_begin(&handle, counter, sizeof(throttle_event), 1, 0);
3485 if (ret)
3486 return;
3487
3488 perf_output_put(&handle, throttle_event);
3489 perf_output_end(&handle);
3490}
3491
3492/*
3493 * Generic counter overflow handling, sampling.
3494 */
3495
3496int perf_counter_overflow(struct perf_counter *counter, int nmi,
3497 struct perf_sample_data *data)
3498{
3499 int events = atomic_read(&counter->event_limit);
3500 int throttle = counter->pmu->unthrottle != NULL;
3501 struct hw_perf_counter *hwc = &counter->hw;
3502 int ret = 0;
3503
3504 if (!throttle) {
3505 hwc->interrupts++;
3506 } else {
3507 if (hwc->interrupts != MAX_INTERRUPTS) {
3508 hwc->interrupts++;
3509 if (HZ * hwc->interrupts >
3510 (u64)sysctl_perf_counter_sample_rate) {
3511 hwc->interrupts = MAX_INTERRUPTS;
3512 perf_log_throttle(counter, 0);
3513 ret = 1;
3514 }
3515 } else {
3516 /*
3517 * Keep re-disabling counters even though on the previous
3518 * pass we disabled it - just in case we raced with a
3519 * sched-in and the counter got enabled again:
3520 */
3521 ret = 1;
3522 }
3523 }
3524
3525 if (counter->attr.freq) {
3526 u64 now = sched_clock();
3527 s64 delta = now - hwc->freq_stamp;
3528
3529 hwc->freq_stamp = now;
3530
3531 if (delta > 0 && delta < TICK_NSEC)
3532 perf_adjust_period(counter, NSEC_PER_SEC / (int)delta);
3533 }
3534
3535 /*
3536 * XXX event_limit might not quite work as expected on inherited
3537 * counters
3538 */
3539
3540 counter->pending_kill = POLL_IN;
3541 if (events && atomic_dec_and_test(&counter->event_limit)) {
3542 ret = 1;
3543 counter->pending_kill = POLL_HUP;
3544 if (nmi) {
3545 counter->pending_disable = 1;
3546 perf_pending_queue(&counter->pending,
3547 perf_pending_counter);
3548 } else
3549 perf_counter_disable(counter);
3550 }
3551
3552 perf_counter_output(counter, nmi, data);
3553 return ret;
3554}
3555
3556/*
3557 * Generic software counter infrastructure
3558 */
3559
3560/*
3561 * We directly increment counter->count and keep a second value in
3562 * counter->hw.period_left to count intervals. This period counter
3563 * is kept in the range [-sample_period, 0] so that we can use the
3564 * sign as trigger.
3565 */
3566
3567static u64 perf_swcounter_set_period(struct perf_counter *counter)
3568{
3569 struct hw_perf_counter *hwc = &counter->hw;
3570 u64 period = hwc->last_period;
3571 u64 nr, offset;
3572 s64 old, val;
3573
3574 hwc->last_period = hwc->sample_period;
3575
3576again:
3577 old = val = atomic64_read(&hwc->period_left);
3578 if (val < 0)
3579 return 0;
3580
3581 nr = div64_u64(period + val, period);
3582 offset = nr * period;
3583 val -= offset;
3584 if (atomic64_cmpxchg(&hwc->period_left, old, val) != old)
3585 goto again;
3586
3587 return nr;
3588}
3589
3590static void perf_swcounter_overflow(struct perf_counter *counter,
3591 int nmi, struct perf_sample_data *data)
3592{
3593 struct hw_perf_counter *hwc = &counter->hw;
3594 u64 overflow;
3595
3596 data->period = counter->hw.last_period;
3597 overflow = perf_swcounter_set_period(counter);
3598
3599 if (hwc->interrupts == MAX_INTERRUPTS)
3600 return;
3601
3602 for (; overflow; overflow--) {
3603 if (perf_counter_overflow(counter, nmi, data)) {
3604 /*
3605 * We inhibit the overflow from happening when
3606 * hwc->interrupts == MAX_INTERRUPTS.
3607 */
3608 break;
3609 }
3610 }
3611}
3612
3613static void perf_swcounter_unthrottle(struct perf_counter *counter)
3614{
3615 /*
3616 * Nothing to do, we already reset hwc->interrupts.
3617 */
3618}
3619
3620static void perf_swcounter_add(struct perf_counter *counter, u64 nr,
3621 int nmi, struct perf_sample_data *data)
3622{
3623 struct hw_perf_counter *hwc = &counter->hw;
3624
3625 atomic64_add(nr, &counter->count);
3626
3627 if (!hwc->sample_period)
3628 return;
3629
3630 if (!data->regs)
3631 return;
3632
3633 if (!atomic64_add_negative(nr, &hwc->period_left))
3634 perf_swcounter_overflow(counter, nmi, data);
3635}
3636
3637static int perf_swcounter_is_counting(struct perf_counter *counter)
3638{
3639 /*
3640 * The counter is active, we're good!
3641 */
3642 if (counter->state == PERF_COUNTER_STATE_ACTIVE)
3643 return 1;
3644
3645 /*
3646 * The counter is off/error, not counting.
3647 */
3648 if (counter->state != PERF_COUNTER_STATE_INACTIVE)
3649 return 0;
3650
3651 /*
3652 * The counter is inactive, if the context is active
3653 * we're part of a group that didn't make it on the 'pmu',
3654 * not counting.
3655 */
3656 if (counter->ctx->is_active)
3657 return 0;
3658
3659 /*
3660 * We're inactive and the context is too, this means the
3661 * task is scheduled out, we're counting events that happen
3662 * to us, like migration events.
3663 */
3664 return 1;
3665}
3666
3667static int perf_swcounter_match(struct perf_counter *counter,
3668 enum perf_type_id type,
3669 u32 event, struct pt_regs *regs)
3670{
3671 if (!perf_swcounter_is_counting(counter))
3672 return 0;
3673
3674 if (counter->attr.type != type)
3675 return 0;
3676 if (counter->attr.config != event)
3677 return 0;
3678
3679 if (regs) {
3680 if (counter->attr.exclude_user && user_mode(regs))
3681 return 0;
3682
3683 if (counter->attr.exclude_kernel && !user_mode(regs))
3684 return 0;
3685 }
3686
3687 return 1;
3688}
3689
3690static void perf_swcounter_ctx_event(struct perf_counter_context *ctx,
3691 enum perf_type_id type,
3692 u32 event, u64 nr, int nmi,
3693 struct perf_sample_data *data)
3694{
3695 struct perf_counter *counter;
3696
3697 if (system_state != SYSTEM_RUNNING || list_empty(&ctx->event_list))
3698 return;
3699
3700 rcu_read_lock();
3701 list_for_each_entry_rcu(counter, &ctx->event_list, event_entry) {
3702 if (perf_swcounter_match(counter, type, event, data->regs))
3703 perf_swcounter_add(counter, nr, nmi, data);
3704 }
3705 rcu_read_unlock();
3706}
3707
3708static int *perf_swcounter_recursion_context(struct perf_cpu_context *cpuctx)
3709{
3710 if (in_nmi())
3711 return &cpuctx->recursion[3];
3712
3713 if (in_irq())
3714 return &cpuctx->recursion[2];
3715
3716 if (in_softirq())
3717 return &cpuctx->recursion[1];
3718
3719 return &cpuctx->recursion[0];
3720}
3721
3722static void do_perf_swcounter_event(enum perf_type_id type, u32 event,
3723 u64 nr, int nmi,
3724 struct perf_sample_data *data)
3725{
3726 struct perf_cpu_context *cpuctx = &get_cpu_var(perf_cpu_context);
3727 int *recursion = perf_swcounter_recursion_context(cpuctx);
3728 struct perf_counter_context *ctx;
3729
3730 if (*recursion)
3731 goto out;
3732
3733 (*recursion)++;
3734 barrier();
3735
3736 perf_swcounter_ctx_event(&cpuctx->ctx, type, event,
3737 nr, nmi, data);
3738 rcu_read_lock();
3739 /*
3740 * doesn't really matter which of the child contexts the
3741 * events ends up in.
3742 */
3743 ctx = rcu_dereference(current->perf_counter_ctxp);
3744 if (ctx)
3745 perf_swcounter_ctx_event(ctx, type, event, nr, nmi, data);
3746 rcu_read_unlock();
3747
3748 barrier();
3749 (*recursion)--;
3750
3751out:
3752 put_cpu_var(perf_cpu_context);
3753}
3754
3755void __perf_swcounter_event(u32 event, u64 nr, int nmi,
3756 struct pt_regs *regs, u64 addr)
3757{
3758 struct perf_sample_data data = {
3759 .regs = regs,
3760 .addr = addr,
3761 };
3762
3763 do_perf_swcounter_event(PERF_TYPE_SOFTWARE, event, nr, nmi, &data);
3764}
3765
3766static void perf_swcounter_read(struct perf_counter *counter)
3767{
3768}
3769
3770static int perf_swcounter_enable(struct perf_counter *counter)
3771{
3772 struct hw_perf_counter *hwc = &counter->hw;
3773
3774 if (hwc->sample_period) {
3775 hwc->last_period = hwc->sample_period;
3776 perf_swcounter_set_period(counter);
3777 }
3778 return 0;
3779}
3780
3781static void perf_swcounter_disable(struct perf_counter *counter)
3782{
3783}
3784
3785static const struct pmu perf_ops_generic = {
3786 .enable = perf_swcounter_enable,
3787 .disable = perf_swcounter_disable,
3788 .read = perf_swcounter_read,
3789 .unthrottle = perf_swcounter_unthrottle,
3790};
3791
3792/*
3793 * hrtimer based swcounter callback
3794 */
3795
3796static enum hrtimer_restart perf_swcounter_hrtimer(struct hrtimer *hrtimer)
3797{
3798 enum hrtimer_restart ret = HRTIMER_RESTART;
3799 struct perf_sample_data data;
3800 struct perf_counter *counter;
3801 u64 period;
3802
3803 counter = container_of(hrtimer, struct perf_counter, hw.hrtimer);
3804 counter->pmu->read(counter);
3805
3806 data.addr = 0;
3807 data.regs = get_irq_regs();
3808 /*
3809 * In case we exclude kernel IPs or are somehow not in interrupt
3810 * context, provide the next best thing, the user IP.
3811 */
3812 if ((counter->attr.exclude_kernel || !data.regs) &&
3813 !counter->attr.exclude_user)
3814 data.regs = task_pt_regs(current);
3815
3816 if (data.regs) {
3817 if (perf_counter_overflow(counter, 0, &data))
3818 ret = HRTIMER_NORESTART;
3819 }
3820
3821 period = max_t(u64, 10000, counter->hw.sample_period);
3822 hrtimer_forward_now(hrtimer, ns_to_ktime(period));
3823
3824 return ret;
3825}
3826
3827/*
3828 * Software counter: cpu wall time clock
3829 */
3830
3831static void cpu_clock_perf_counter_update(struct perf_counter *counter)
3832{
3833 int cpu = raw_smp_processor_id();
3834 s64 prev;
3835 u64 now;
3836
3837 now = cpu_clock(cpu);
3838 prev = atomic64_read(&counter->hw.prev_count);
3839 atomic64_set(&counter->hw.prev_count, now);
3840 atomic64_add(now - prev, &counter->count);
3841}
3842
3843static int cpu_clock_perf_counter_enable(struct perf_counter *counter)
3844{
3845 struct hw_perf_counter *hwc = &counter->hw;
3846 int cpu = raw_smp_processor_id();
3847
3848 atomic64_set(&hwc->prev_count, cpu_clock(cpu));
3849 hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
3850 hwc->hrtimer.function = perf_swcounter_hrtimer;
3851 if (hwc->sample_period) {
3852 u64 period = max_t(u64, 10000, hwc->sample_period);
3853 __hrtimer_start_range_ns(&hwc->hrtimer,
3854 ns_to_ktime(period), 0,
3855 HRTIMER_MODE_REL, 0);
3856 }
3857
3858 return 0;
3859}
3860
3861static void cpu_clock_perf_counter_disable(struct perf_counter *counter)
3862{
3863 if (counter->hw.sample_period)
3864 hrtimer_cancel(&counter->hw.hrtimer);
3865 cpu_clock_perf_counter_update(counter);
3866}
3867
3868static void cpu_clock_perf_counter_read(struct perf_counter *counter)
3869{
3870 cpu_clock_perf_counter_update(counter);
3871}
3872
3873static const struct pmu perf_ops_cpu_clock = {
3874 .enable = cpu_clock_perf_counter_enable,
3875 .disable = cpu_clock_perf_counter_disable,
3876 .read = cpu_clock_perf_counter_read,
3877};
3878
3879/*
3880 * Software counter: task time clock
3881 */
3882
3883static void task_clock_perf_counter_update(struct perf_counter *counter, u64 now)
3884{
3885 u64 prev;
3886 s64 delta;
3887
3888 prev = atomic64_xchg(&counter->hw.prev_count, now);
3889 delta = now - prev;
3890 atomic64_add(delta, &counter->count);
3891}
3892
3893static int task_clock_perf_counter_enable(struct perf_counter *counter)
3894{
3895 struct hw_perf_counter *hwc = &counter->hw;
3896 u64 now;
3897
3898 now = counter->ctx->time;
3899
3900 atomic64_set(&hwc->prev_count, now);
3901 hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
3902 hwc->hrtimer.function = perf_swcounter_hrtimer;
3903 if (hwc->sample_period) {
3904 u64 period = max_t(u64, 10000, hwc->sample_period);
3905 __hrtimer_start_range_ns(&hwc->hrtimer,
3906 ns_to_ktime(period), 0,
3907 HRTIMER_MODE_REL, 0);
3908 }
3909
3910 return 0;
3911}
3912
3913static void task_clock_perf_counter_disable(struct perf_counter *counter)
3914{
3915 if (counter->hw.sample_period)
3916 hrtimer_cancel(&counter->hw.hrtimer);
3917 task_clock_perf_counter_update(counter, counter->ctx->time);
3918
3919}
3920
3921static void task_clock_perf_counter_read(struct perf_counter *counter)
3922{
3923 u64 time;
3924
3925 if (!in_nmi()) {
3926 update_context_time(counter->ctx);
3927 time = counter->ctx->time;
3928 } else {
3929 u64 now = perf_clock();
3930 u64 delta = now - counter->ctx->timestamp;
3931 time = counter->ctx->time + delta;
3932 }
3933
3934 task_clock_perf_counter_update(counter, time);
3935}
3936
3937static const struct pmu perf_ops_task_clock = {
3938 .enable = task_clock_perf_counter_enable,
3939 .disable = task_clock_perf_counter_disable,
3940 .read = task_clock_perf_counter_read,
3941};
3942
3943#ifdef CONFIG_EVENT_PROFILE
3944void perf_tpcounter_event(int event_id, u64 addr, u64 count, void *record,
3945 int entry_size)
3946{
3947 struct perf_raw_record raw = {
3948 .size = entry_size,
3949 .data = record,
3950 };
3951
3952 struct perf_sample_data data = {
3953 .regs = get_irq_regs(),
3954 .addr = addr,
3955 .raw = &raw,
3956 };
3957
3958 if (!data.regs)
3959 data.regs = task_pt_regs(current);
3960
3961 do_perf_swcounter_event(PERF_TYPE_TRACEPOINT, event_id, count, 1, &data);
3962}
3963EXPORT_SYMBOL_GPL(perf_tpcounter_event);
3964
3965extern int ftrace_profile_enable(int);
3966extern void ftrace_profile_disable(int);
3967
3968static void tp_perf_counter_destroy(struct perf_counter *counter)
3969{
3970 ftrace_profile_disable(counter->attr.config);
3971}
3972
3973static const struct pmu *tp_perf_counter_init(struct perf_counter *counter)
3974{
3975 /*
3976 * Raw tracepoint data is a severe data leak, only allow root to
3977 * have these.
3978 */
3979 if ((counter->attr.sample_type & PERF_SAMPLE_RAW) &&
3980 perf_paranoid_tracepoint_raw() &&
3981 !capable(CAP_SYS_ADMIN))
3982 return ERR_PTR(-EPERM);
3983
3984 if (ftrace_profile_enable(counter->attr.config))
3985 return NULL;
3986
3987 counter->destroy = tp_perf_counter_destroy;
3988
3989 return &perf_ops_generic;
3990}
3991#else
3992static const struct pmu *tp_perf_counter_init(struct perf_counter *counter)
3993{
3994 return NULL;
3995}
3996#endif
3997
3998atomic_t perf_swcounter_enabled[PERF_COUNT_SW_MAX];
3999
4000static void sw_perf_counter_destroy(struct perf_counter *counter)
4001{
4002 u64 event = counter->attr.config;
4003
4004 WARN_ON(counter->parent);
4005
4006 atomic_dec(&perf_swcounter_enabled[event]);
4007}
4008
4009static const struct pmu *sw_perf_counter_init(struct perf_counter *counter)
4010{
4011 const struct pmu *pmu = NULL;
4012 u64 event = counter->attr.config;
4013
4014 /*
4015 * Software counters (currently) can't in general distinguish
4016 * between user, kernel and hypervisor events.
4017 * However, context switches and cpu migrations are considered
4018 * to be kernel events, and page faults are never hypervisor
4019 * events.
4020 */
4021 switch (event) {
4022 case PERF_COUNT_SW_CPU_CLOCK:
4023 pmu = &perf_ops_cpu_clock;
4024
4025 break;
4026 case PERF_COUNT_SW_TASK_CLOCK:
4027 /*
4028 * If the user instantiates this as a per-cpu counter,
4029 * use the cpu_clock counter instead.
4030 */
4031 if (counter->ctx->task)
4032 pmu = &perf_ops_task_clock;
4033 else
4034 pmu = &perf_ops_cpu_clock;
4035
4036 break;
4037 case PERF_COUNT_SW_PAGE_FAULTS:
4038 case PERF_COUNT_SW_PAGE_FAULTS_MIN:
4039 case PERF_COUNT_SW_PAGE_FAULTS_MAJ:
4040 case PERF_COUNT_SW_CONTEXT_SWITCHES:
4041 case PERF_COUNT_SW_CPU_MIGRATIONS:
4042 if (!counter->parent) {
4043 atomic_inc(&perf_swcounter_enabled[event]);
4044 counter->destroy = sw_perf_counter_destroy;
4045 }
4046 pmu = &perf_ops_generic;
4047 break;
4048 }
4049
4050 return pmu;
4051}
4052
4053/*
4054 * Allocate and initialize a counter structure
4055 */
4056static struct perf_counter *
4057perf_counter_alloc(struct perf_counter_attr *attr,
4058 int cpu,
4059 struct perf_counter_context *ctx,
4060 struct perf_counter *group_leader,
4061 struct perf_counter *parent_counter,
4062 gfp_t gfpflags)
4063{
4064 const struct pmu *pmu;
4065 struct perf_counter *counter;
4066 struct hw_perf_counter *hwc;
4067 long err;
4068
4069 counter = kzalloc(sizeof(*counter), gfpflags);
4070 if (!counter)
4071 return ERR_PTR(-ENOMEM);
4072
4073 /*
4074 * Single counters are their own group leaders, with an
4075 * empty sibling list:
4076 */
4077 if (!group_leader)
4078 group_leader = counter;
4079
4080 mutex_init(&counter->child_mutex);
4081 INIT_LIST_HEAD(&counter->child_list);
4082
4083 INIT_LIST_HEAD(&counter->list_entry);
4084 INIT_LIST_HEAD(&counter->event_entry);
4085 INIT_LIST_HEAD(&counter->sibling_list);
4086 init_waitqueue_head(&counter->waitq);
4087
4088 mutex_init(&counter->mmap_mutex);
4089
4090 counter->cpu = cpu;
4091 counter->attr = *attr;
4092 counter->group_leader = group_leader;
4093 counter->pmu = NULL;
4094 counter->ctx = ctx;
4095 counter->oncpu = -1;
4096
4097 counter->parent = parent_counter;
4098
4099 counter->ns = get_pid_ns(current->nsproxy->pid_ns);
4100 counter->id = atomic64_inc_return(&perf_counter_id);
4101
4102 counter->state = PERF_COUNTER_STATE_INACTIVE;
4103
4104 if (attr->disabled)
4105 counter->state = PERF_COUNTER_STATE_OFF;
4106
4107 pmu = NULL;
4108
4109 hwc = &counter->hw;
4110 hwc->sample_period = attr->sample_period;
4111 if (attr->freq && attr->sample_freq)
4112 hwc->sample_period = 1;
4113 hwc->last_period = hwc->sample_period;
4114
4115 atomic64_set(&hwc->period_left, hwc->sample_period);
4116
4117 /*
4118 * we currently do not support PERF_FORMAT_GROUP on inherited counters
4119 */
4120 if (attr->inherit && (attr->read_format & PERF_FORMAT_GROUP))
4121 goto done;
4122
4123 switch (attr->type) {
4124 case PERF_TYPE_RAW:
4125 case PERF_TYPE_HARDWARE:
4126 case PERF_TYPE_HW_CACHE:
4127 pmu = hw_perf_counter_init(counter);
4128 break;
4129
4130 case PERF_TYPE_SOFTWARE:
4131 pmu = sw_perf_counter_init(counter);
4132 break;
4133
4134 case PERF_TYPE_TRACEPOINT:
4135 pmu = tp_perf_counter_init(counter);
4136 break;
4137
4138 default:
4139 break;
4140 }
4141done:
4142 err = 0;
4143 if (!pmu)
4144 err = -EINVAL;
4145 else if (IS_ERR(pmu))
4146 err = PTR_ERR(pmu);
4147
4148 if (err) {
4149 if (counter->ns)
4150 put_pid_ns(counter->ns);
4151 kfree(counter);
4152 return ERR_PTR(err);
4153 }
4154
4155 counter->pmu = pmu;
4156
4157 if (!counter->parent) {
4158 atomic_inc(&nr_counters);
4159 if (counter->attr.mmap)
4160 atomic_inc(&nr_mmap_counters);
4161 if (counter->attr.comm)
4162 atomic_inc(&nr_comm_counters);
4163 if (counter->attr.task)
4164 atomic_inc(&nr_task_counters);
4165 }
4166
4167 return counter;
4168}
4169
4170static int perf_copy_attr(struct perf_counter_attr __user *uattr,
4171 struct perf_counter_attr *attr)
4172{
4173 int ret;
4174 u32 size;
4175
4176 if (!access_ok(VERIFY_WRITE, uattr, PERF_ATTR_SIZE_VER0))
4177 return -EFAULT;
4178
4179 /*
4180 * zero the full structure, so that a short copy will be nice.
4181 */
4182 memset(attr, 0, sizeof(*attr));
4183
4184 ret = get_user(size, &uattr->size);
4185 if (ret)
4186 return ret;
4187
4188 if (size > PAGE_SIZE) /* silly large */
4189 goto err_size;
4190
4191 if (!size) /* abi compat */
4192 size = PERF_ATTR_SIZE_VER0;
4193
4194 if (size < PERF_ATTR_SIZE_VER0)
4195 goto err_size;
4196
4197 /*
4198 * If we're handed a bigger struct than we know of,
4199 * ensure all the unknown bits are 0.
4200 */
4201 if (size > sizeof(*attr)) {
4202 unsigned long val;
4203 unsigned long __user *addr;
4204 unsigned long __user *end;
4205
4206 addr = PTR_ALIGN((void __user *)uattr + sizeof(*attr),
4207 sizeof(unsigned long));
4208 end = PTR_ALIGN((void __user *)uattr + size,
4209 sizeof(unsigned long));
4210
4211 for (; addr < end; addr += sizeof(unsigned long)) {
4212 ret = get_user(val, addr);
4213 if (ret)
4214 return ret;
4215 if (val)
4216 goto err_size;
4217 }
4218 }
4219
4220 ret = copy_from_user(attr, uattr, size);
4221 if (ret)
4222 return -EFAULT;
4223
4224 /*
4225 * If the type exists, the corresponding creation will verify
4226 * the attr->config.
4227 */
4228 if (attr->type >= PERF_TYPE_MAX)
4229 return -EINVAL;
4230
4231 if (attr->__reserved_1 || attr->__reserved_2 || attr->__reserved_3)
4232 return -EINVAL;
4233
4234 if (attr->sample_type & ~(PERF_SAMPLE_MAX-1))
4235 return -EINVAL;
4236
4237 if (attr->read_format & ~(PERF_FORMAT_MAX-1))
4238 return -EINVAL;
4239
4240out:
4241 return ret;
4242
4243err_size:
4244 put_user(sizeof(*attr), &uattr->size);
4245 ret = -E2BIG;
4246 goto out;
4247}
4248
4249int perf_counter_set_output(struct perf_counter *counter, int output_fd)
4250{
4251 struct perf_counter *output_counter = NULL;
4252 struct file *output_file = NULL;
4253 struct perf_counter *old_output;
4254 int fput_needed = 0;
4255 int ret = -EINVAL;
4256
4257 if (!output_fd)
4258 goto set;
4259
4260 output_file = fget_light(output_fd, &fput_needed);
4261 if (!output_file)
4262 return -EBADF;
4263
4264 if (output_file->f_op != &perf_fops)
4265 goto out;
4266
4267 output_counter = output_file->private_data;
4268
4269 /* Don't chain output fds */
4270 if (output_counter->output)
4271 goto out;
4272
4273 /* Don't set an output fd when we already have an output channel */
4274 if (counter->data)
4275 goto out;
4276
4277 atomic_long_inc(&output_file->f_count);
4278
4279set:
4280 mutex_lock(&counter->mmap_mutex);
4281 old_output = counter->output;
4282 rcu_assign_pointer(counter->output, output_counter);
4283 mutex_unlock(&counter->mmap_mutex);
4284
4285 if (old_output) {
4286 /*
4287 * we need to make sure no existing perf_output_*()
4288 * is still referencing this counter.
4289 */
4290 synchronize_rcu();
4291 fput(old_output->filp);
4292 }
4293
4294 ret = 0;
4295out:
4296 fput_light(output_file, fput_needed);
4297 return ret;
4298}
4299
4300/**
4301 * sys_perf_counter_open - open a performance counter, associate it to a task/cpu
4302 *
4303 * @attr_uptr: event type attributes for monitoring/sampling
4304 * @pid: target pid
4305 * @cpu: target cpu
4306 * @group_fd: group leader counter fd
4307 */
4308SYSCALL_DEFINE5(perf_counter_open,
4309 struct perf_counter_attr __user *, attr_uptr,
4310 pid_t, pid, int, cpu, int, group_fd, unsigned long, flags)
4311{
4312 struct perf_counter *counter, *group_leader;
4313 struct perf_counter_attr attr;
4314 struct perf_counter_context *ctx;
4315 struct file *counter_file = NULL;
4316 struct file *group_file = NULL;
4317 int fput_needed = 0;
4318 int fput_needed2 = 0;
4319 int err;
4320
4321 /* for future expandability... */
4322 if (flags & ~(PERF_FLAG_FD_NO_GROUP | PERF_FLAG_FD_OUTPUT))
4323 return -EINVAL;
4324
4325 err = perf_copy_attr(attr_uptr, &attr);
4326 if (err)
4327 return err;
4328
4329 if (!attr.exclude_kernel) {
4330 if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
4331 return -EACCES;
4332 }
4333
4334 if (attr.freq) {
4335 if (attr.sample_freq > sysctl_perf_counter_sample_rate)
4336 return -EINVAL;
4337 }
4338
4339 /*
4340 * Get the target context (task or percpu):
4341 */
4342 ctx = find_get_context(pid, cpu);
4343 if (IS_ERR(ctx))
4344 return PTR_ERR(ctx);
4345
4346 /*
4347 * Look up the group leader (we will attach this counter to it):
4348 */
4349 group_leader = NULL;
4350 if (group_fd != -1 && !(flags & PERF_FLAG_FD_NO_GROUP)) {
4351 err = -EINVAL;
4352 group_file = fget_light(group_fd, &fput_needed);
4353 if (!group_file)
4354 goto err_put_context;
4355 if (group_file->f_op != &perf_fops)
4356 goto err_put_context;
4357
4358 group_leader = group_file->private_data;
4359 /*
4360 * Do not allow a recursive hierarchy (this new sibling
4361 * becoming part of another group-sibling):
4362 */
4363 if (group_leader->group_leader != group_leader)
4364 goto err_put_context;
4365 /*
4366 * Do not allow to attach to a group in a different
4367 * task or CPU context:
4368 */
4369 if (group_leader->ctx != ctx)
4370 goto err_put_context;
4371 /*
4372 * Only a group leader can be exclusive or pinned
4373 */
4374 if (attr.exclusive || attr.pinned)
4375 goto err_put_context;
4376 }
4377
4378 counter = perf_counter_alloc(&attr, cpu, ctx, group_leader,
4379 NULL, GFP_KERNEL);
4380 err = PTR_ERR(counter);
4381 if (IS_ERR(counter))
4382 goto err_put_context;
4383
4384 err = anon_inode_getfd("[perf_counter]", &perf_fops, counter, 0);
4385 if (err < 0)
4386 goto err_free_put_context;
4387
4388 counter_file = fget_light(err, &fput_needed2);
4389 if (!counter_file)
4390 goto err_free_put_context;
4391
4392 if (flags & PERF_FLAG_FD_OUTPUT) {
4393 err = perf_counter_set_output(counter, group_fd);
4394 if (err)
4395 goto err_fput_free_put_context;
4396 }
4397
4398 counter->filp = counter_file;
4399 WARN_ON_ONCE(ctx->parent_ctx);
4400 mutex_lock(&ctx->mutex);
4401 perf_install_in_context(ctx, counter, cpu);
4402 ++ctx->generation;
4403 mutex_unlock(&ctx->mutex);
4404
4405 counter->owner = current;
4406 get_task_struct(current);
4407 mutex_lock(&current->perf_counter_mutex);
4408 list_add_tail(&counter->owner_entry, &current->perf_counter_list);
4409 mutex_unlock(&current->perf_counter_mutex);
4410
4411err_fput_free_put_context:
4412 fput_light(counter_file, fput_needed2);
4413
4414err_free_put_context:
4415 if (err < 0)
4416 kfree(counter);
4417
4418err_put_context:
4419 if (err < 0)
4420 put_ctx(ctx);
4421
4422 fput_light(group_file, fput_needed);
4423
4424 return err;
4425}
4426
4427/*
4428 * inherit a counter from parent task to child task:
4429 */
4430static struct perf_counter *
4431inherit_counter(struct perf_counter *parent_counter,
4432 struct task_struct *parent,
4433 struct perf_counter_context *parent_ctx,
4434 struct task_struct *child,
4435 struct perf_counter *group_leader,
4436 struct perf_counter_context *child_ctx)
4437{
4438 struct perf_counter *child_counter;
4439
4440 /*
4441 * Instead of creating recursive hierarchies of counters,
4442 * we link inherited counters back to the original parent,
4443 * which has a filp for sure, which we use as the reference
4444 * count:
4445 */
4446 if (parent_counter->parent)
4447 parent_counter = parent_counter->parent;
4448
4449 child_counter = perf_counter_alloc(&parent_counter->attr,
4450 parent_counter->cpu, child_ctx,
4451 group_leader, parent_counter,
4452 GFP_KERNEL);
4453 if (IS_ERR(child_counter))
4454 return child_counter;
4455 get_ctx(child_ctx);
4456
4457 /*
4458 * Make the child state follow the state of the parent counter,
4459 * not its attr.disabled bit. We hold the parent's mutex,
4460 * so we won't race with perf_counter_{en, dis}able_family.
4461 */
4462 if (parent_counter->state >= PERF_COUNTER_STATE_INACTIVE)
4463 child_counter->state = PERF_COUNTER_STATE_INACTIVE;
4464 else
4465 child_counter->state = PERF_COUNTER_STATE_OFF;
4466
4467 if (parent_counter->attr.freq)
4468 child_counter->hw.sample_period = parent_counter->hw.sample_period;
4469
4470 /*
4471 * Link it up in the child's context:
4472 */
4473 add_counter_to_ctx(child_counter, child_ctx);
4474
4475 /*
4476 * Get a reference to the parent filp - we will fput it
4477 * when the child counter exits. This is safe to do because
4478 * we are in the parent and we know that the filp still
4479 * exists and has a nonzero count:
4480 */
4481 atomic_long_inc(&parent_counter->filp->f_count);
4482
4483 /*
4484 * Link this into the parent counter's child list
4485 */
4486 WARN_ON_ONCE(parent_counter->ctx->parent_ctx);
4487 mutex_lock(&parent_counter->child_mutex);
4488 list_add_tail(&child_counter->child_list, &parent_counter->child_list);
4489 mutex_unlock(&parent_counter->child_mutex);
4490
4491 return child_counter;
4492}
4493
4494static int inherit_group(struct perf_counter *parent_counter,
4495 struct task_struct *parent,
4496 struct perf_counter_context *parent_ctx,
4497 struct task_struct *child,
4498 struct perf_counter_context *child_ctx)
4499{
4500 struct perf_counter *leader;
4501 struct perf_counter *sub;
4502 struct perf_counter *child_ctr;
4503
4504 leader = inherit_counter(parent_counter, parent, parent_ctx,
4505 child, NULL, child_ctx);
4506 if (IS_ERR(leader))
4507 return PTR_ERR(leader);
4508 list_for_each_entry(sub, &parent_counter->sibling_list, list_entry) {
4509 child_ctr = inherit_counter(sub, parent, parent_ctx,
4510 child, leader, child_ctx);
4511 if (IS_ERR(child_ctr))
4512 return PTR_ERR(child_ctr);
4513 }
4514 return 0;
4515}
4516
4517static void sync_child_counter(struct perf_counter *child_counter,
4518 struct task_struct *child)
4519{
4520 struct perf_counter *parent_counter = child_counter->parent;
4521 u64 child_val;
4522
4523 if (child_counter->attr.inherit_stat)
4524 perf_counter_read_event(child_counter, child);
4525
4526 child_val = atomic64_read(&child_counter->count);
4527
4528 /*
4529 * Add back the child's count to the parent's count:
4530 */
4531 atomic64_add(child_val, &parent_counter->count);
4532 atomic64_add(child_counter->total_time_enabled,
4533 &parent_counter->child_total_time_enabled);
4534 atomic64_add(child_counter->total_time_running,
4535 &parent_counter->child_total_time_running);
4536
4537 /*
4538 * Remove this counter from the parent's list
4539 */
4540 WARN_ON_ONCE(parent_counter->ctx->parent_ctx);
4541 mutex_lock(&parent_counter->child_mutex);
4542 list_del_init(&child_counter->child_list);
4543 mutex_unlock(&parent_counter->child_mutex);
4544
4545 /*
4546 * Release the parent counter, if this was the last
4547 * reference to it.
4548 */
4549 fput(parent_counter->filp);
4550}
4551
4552static void
4553__perf_counter_exit_task(struct perf_counter *child_counter,
4554 struct perf_counter_context *child_ctx,
4555 struct task_struct *child)
4556{
4557 struct perf_counter *parent_counter;
4558
4559 update_counter_times(child_counter);
4560 perf_counter_remove_from_context(child_counter);
4561
4562 parent_counter = child_counter->parent;
4563 /*
4564 * It can happen that parent exits first, and has counters
4565 * that are still around due to the child reference. These
4566 * counters need to be zapped - but otherwise linger.
4567 */
4568 if (parent_counter) {
4569 sync_child_counter(child_counter, child);
4570 free_counter(child_counter);
4571 }
4572}
4573
4574/*
4575 * When a child task exits, feed back counter values to parent counters.
4576 */
4577void perf_counter_exit_task(struct task_struct *child)
4578{
4579 struct perf_counter *child_counter, *tmp;
4580 struct perf_counter_context *child_ctx;
4581 unsigned long flags;
4582
4583 if (likely(!child->perf_counter_ctxp)) {
4584 perf_counter_task(child, NULL, 0);
4585 return;
4586 }
4587
4588 local_irq_save(flags);
4589 /*
4590 * We can't reschedule here because interrupts are disabled,
4591 * and either child is current or it is a task that can't be
4592 * scheduled, so we are now safe from rescheduling changing
4593 * our context.
4594 */
4595 child_ctx = child->perf_counter_ctxp;
4596 __perf_counter_task_sched_out(child_ctx);
4597
4598 /*
4599 * Take the context lock here so that if find_get_context is
4600 * reading child->perf_counter_ctxp, we wait until it has
4601 * incremented the context's refcount before we do put_ctx below.
4602 */
4603 spin_lock(&child_ctx->lock);
4604 child->perf_counter_ctxp = NULL;
4605 /*
4606 * If this context is a clone; unclone it so it can't get
4607 * swapped to another process while we're removing all
4608 * the counters from it.
4609 */
4610 unclone_ctx(child_ctx);
4611 spin_unlock_irqrestore(&child_ctx->lock, flags);
4612
4613 /*
4614 * Report the task dead after unscheduling the counters so that we
4615 * won't get any samples after PERF_EVENT_EXIT. We can however still
4616 * get a few PERF_EVENT_READ events.
4617 */
4618 perf_counter_task(child, child_ctx, 0);
4619
4620 /*
4621 * We can recurse on the same lock type through:
4622 *
4623 * __perf_counter_exit_task()
4624 * sync_child_counter()
4625 * fput(parent_counter->filp)
4626 * perf_release()
4627 * mutex_lock(&ctx->mutex)
4628 *
4629 * But since its the parent context it won't be the same instance.
4630 */
4631 mutex_lock_nested(&child_ctx->mutex, SINGLE_DEPTH_NESTING);
4632
4633again:
4634 list_for_each_entry_safe(child_counter, tmp, &child_ctx->counter_list,
4635 list_entry)
4636 __perf_counter_exit_task(child_counter, child_ctx, child);
4637
4638 /*
4639 * If the last counter was a group counter, it will have appended all
4640 * its siblings to the list, but we obtained 'tmp' before that which
4641 * will still point to the list head terminating the iteration.
4642 */
4643 if (!list_empty(&child_ctx->counter_list))
4644 goto again;
4645
4646 mutex_unlock(&child_ctx->mutex);
4647
4648 put_ctx(child_ctx);
4649}
4650
4651/*
4652 * free an unexposed, unused context as created by inheritance by
4653 * init_task below, used by fork() in case of fail.
4654 */
4655void perf_counter_free_task(struct task_struct *task)
4656{
4657 struct perf_counter_context *ctx = task->perf_counter_ctxp;
4658 struct perf_counter *counter, *tmp;
4659
4660 if (!ctx)
4661 return;
4662
4663 mutex_lock(&ctx->mutex);
4664again:
4665 list_for_each_entry_safe(counter, tmp, &ctx->counter_list, list_entry) {
4666 struct perf_counter *parent = counter->parent;
4667
4668 if (WARN_ON_ONCE(!parent))
4669 continue;
4670
4671 mutex_lock(&parent->child_mutex);
4672 list_del_init(&counter->child_list);
4673 mutex_unlock(&parent->child_mutex);
4674
4675 fput(parent->filp);
4676
4677 list_del_counter(counter, ctx);
4678 free_counter(counter);
4679 }
4680
4681 if (!list_empty(&ctx->counter_list))
4682 goto again;
4683
4684 mutex_unlock(&ctx->mutex);
4685
4686 put_ctx(ctx);
4687}
4688
4689/*
4690 * Initialize the perf_counter context in task_struct
4691 */
4692int perf_counter_init_task(struct task_struct *child)
4693{
4694 struct perf_counter_context *child_ctx, *parent_ctx;
4695 struct perf_counter_context *cloned_ctx;
4696 struct perf_counter *counter;
4697 struct task_struct *parent = current;
4698 int inherited_all = 1;
4699 int ret = 0;
4700
4701 child->perf_counter_ctxp = NULL;
4702
4703 mutex_init(&child->perf_counter_mutex);
4704 INIT_LIST_HEAD(&child->perf_counter_list);
4705
4706 if (likely(!parent->perf_counter_ctxp))
4707 return 0;
4708
4709 /*
4710 * This is executed from the parent task context, so inherit
4711 * counters that have been marked for cloning.
4712 * First allocate and initialize a context for the child.
4713 */
4714
4715 child_ctx = kmalloc(sizeof(struct perf_counter_context), GFP_KERNEL);
4716 if (!child_ctx)
4717 return -ENOMEM;
4718
4719 __perf_counter_init_context(child_ctx, child);
4720 child->perf_counter_ctxp = child_ctx;
4721 get_task_struct(child);
4722
4723 /*
4724 * If the parent's context is a clone, pin it so it won't get
4725 * swapped under us.
4726 */
4727 parent_ctx = perf_pin_task_context(parent);
4728
4729 /*
4730 * No need to check if parent_ctx != NULL here; since we saw
4731 * it non-NULL earlier, the only reason for it to become NULL
4732 * is if we exit, and since we're currently in the middle of
4733 * a fork we can't be exiting at the same time.
4734 */
4735
4736 /*
4737 * Lock the parent list. No need to lock the child - not PID
4738 * hashed yet and not running, so nobody can access it.
4739 */
4740 mutex_lock(&parent_ctx->mutex);
4741
4742 /*
4743 * We dont have to disable NMIs - we are only looking at
4744 * the list, not manipulating it:
4745 */
4746 list_for_each_entry_rcu(counter, &parent_ctx->event_list, event_entry) {
4747 if (counter != counter->group_leader)
4748 continue;
4749
4750 if (!counter->attr.inherit) {
4751 inherited_all = 0;
4752 continue;
4753 }
4754
4755 ret = inherit_group(counter, parent, parent_ctx,
4756 child, child_ctx);
4757 if (ret) {
4758 inherited_all = 0;
4759 break;
4760 }
4761 }
4762
4763 if (inherited_all) {
4764 /*
4765 * Mark the child context as a clone of the parent
4766 * context, or of whatever the parent is a clone of.
4767 * Note that if the parent is a clone, it could get
4768 * uncloned at any point, but that doesn't matter
4769 * because the list of counters and the generation
4770 * count can't have changed since we took the mutex.
4771 */
4772 cloned_ctx = rcu_dereference(parent_ctx->parent_ctx);
4773 if (cloned_ctx) {
4774 child_ctx->parent_ctx = cloned_ctx;
4775 child_ctx->parent_gen = parent_ctx->parent_gen;
4776 } else {
4777 child_ctx->parent_ctx = parent_ctx;
4778 child_ctx->parent_gen = parent_ctx->generation;
4779 }
4780 get_ctx(child_ctx->parent_ctx);
4781 }
4782
4783 mutex_unlock(&parent_ctx->mutex);
4784
4785 perf_unpin_context(parent_ctx);
4786
4787 return ret;
4788}
4789
4790static void __cpuinit perf_counter_init_cpu(int cpu)
4791{
4792 struct perf_cpu_context *cpuctx;
4793
4794 cpuctx = &per_cpu(perf_cpu_context, cpu);
4795 __perf_counter_init_context(&cpuctx->ctx, NULL);
4796
4797 spin_lock(&perf_resource_lock);
4798 cpuctx->max_pertask = perf_max_counters - perf_reserved_percpu;
4799 spin_unlock(&perf_resource_lock);
4800
4801 hw_perf_counter_setup(cpu);
4802}
4803
4804#ifdef CONFIG_HOTPLUG_CPU
4805static void __perf_counter_exit_cpu(void *info)
4806{
4807 struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
4808 struct perf_counter_context *ctx = &cpuctx->ctx;
4809 struct perf_counter *counter, *tmp;
4810
4811 list_for_each_entry_safe(counter, tmp, &ctx->counter_list, list_entry)
4812 __perf_counter_remove_from_context(counter);
4813}
4814static void perf_counter_exit_cpu(int cpu)
4815{
4816 struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
4817 struct perf_counter_context *ctx = &cpuctx->ctx;
4818
4819 mutex_lock(&ctx->mutex);
4820 smp_call_function_single(cpu, __perf_counter_exit_cpu, NULL, 1);
4821 mutex_unlock(&ctx->mutex);
4822}
4823#else
4824static inline void perf_counter_exit_cpu(int cpu) { }
4825#endif
4826
4827static int __cpuinit
4828perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)
4829{
4830 unsigned int cpu = (long)hcpu;
4831
4832 switch (action) {
4833
4834 case CPU_UP_PREPARE:
4835 case CPU_UP_PREPARE_FROZEN:
4836 perf_counter_init_cpu(cpu);
4837 break;
4838
4839 case CPU_ONLINE:
4840 case CPU_ONLINE_FROZEN:
4841 hw_perf_counter_setup_online(cpu);
4842 break;
4843
4844 case CPU_DOWN_PREPARE:
4845 case CPU_DOWN_PREPARE_FROZEN:
4846 perf_counter_exit_cpu(cpu);
4847 break;
4848
4849 default:
4850 break;
4851 }
4852
4853 return NOTIFY_OK;
4854}
4855
4856/*
4857 * This has to have a higher priority than migration_notifier in sched.c.
4858 */
4859static struct notifier_block __cpuinitdata perf_cpu_nb = {
4860 .notifier_call = perf_cpu_notify,
4861 .priority = 20,
4862};
4863
4864void __init perf_counter_init(void)
4865{
4866 perf_cpu_notify(&perf_cpu_nb, (unsigned long)CPU_UP_PREPARE,
4867 (void *)(long)smp_processor_id());
4868 perf_cpu_notify(&perf_cpu_nb, (unsigned long)CPU_ONLINE,
4869 (void *)(long)smp_processor_id());
4870 register_cpu_notifier(&perf_cpu_nb);
4871}
4872
4873static ssize_t perf_show_reserve_percpu(struct sysdev_class *class, char *buf)
4874{
4875 return sprintf(buf, "%d\n", perf_reserved_percpu);
4876}
4877
4878static ssize_t
4879perf_set_reserve_percpu(struct sysdev_class *class,
4880 const char *buf,
4881 size_t count)
4882{
4883 struct perf_cpu_context *cpuctx;
4884 unsigned long val;
4885 int err, cpu, mpt;
4886
4887 err = strict_strtoul(buf, 10, &val);
4888 if (err)
4889 return err;
4890 if (val > perf_max_counters)
4891 return -EINVAL;
4892
4893 spin_lock(&perf_resource_lock);
4894 perf_reserved_percpu = val;
4895 for_each_online_cpu(cpu) {
4896 cpuctx = &per_cpu(perf_cpu_context, cpu);
4897 spin_lock_irq(&cpuctx->ctx.lock);
4898 mpt = min(perf_max_counters - cpuctx->ctx.nr_counters,
4899 perf_max_counters - perf_reserved_percpu);
4900 cpuctx->max_pertask = mpt;
4901 spin_unlock_irq(&cpuctx->ctx.lock);
4902 }
4903 spin_unlock(&perf_resource_lock);
4904
4905 return count;
4906}
4907
4908static ssize_t perf_show_overcommit(struct sysdev_class *class, char *buf)
4909{
4910 return sprintf(buf, "%d\n", perf_overcommit);
4911}
4912
4913static ssize_t
4914perf_set_overcommit(struct sysdev_class *class, const char *buf, size_t count)
4915{
4916 unsigned long val;
4917 int err;
4918
4919 err = strict_strtoul(buf, 10, &val);
4920 if (err)
4921 return err;
4922 if (val > 1)
4923 return -EINVAL;
4924
4925 spin_lock(&perf_resource_lock);
4926 perf_overcommit = val;
4927 spin_unlock(&perf_resource_lock);
4928
4929 return count;
4930}
4931
4932static SYSDEV_CLASS_ATTR(
4933 reserve_percpu,
4934 0644,
4935 perf_show_reserve_percpu,
4936 perf_set_reserve_percpu
4937 );
4938
4939static SYSDEV_CLASS_ATTR(
4940 overcommit,
4941 0644,
4942 perf_show_overcommit,
4943 perf_set_overcommit
4944 );
4945
4946static struct attribute *perfclass_attrs[] = {
4947 &attr_reserve_percpu.attr,
4948 &attr_overcommit.attr,
4949 NULL
4950};
4951
4952static struct attribute_group perfclass_attr_group = {
4953 .attrs = perfclass_attrs,
4954 .name = "perf_counters",
4955};
4956
4957static int __init perf_counter_sysfs_init(void)
4958{
4959 return sysfs_create_group(&cpu_sysdev_class.kset.kobj,
4960 &perfclass_attr_group);
4961}
4962device_initcall(perf_counter_sysfs_init);
generated by cgit v1.2.2 (git 2.25.0) at 2025-02-27 09:53:42 -0500