Root/kernel/perf_event.c

<
1/*
2 * Performance events 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/idr.h>
17#include <linux/file.h>
18#include <linux/poll.h>
19#include <linux/slab.h>
20#include <linux/hash.h>
21#include <linux/sysfs.h>
22#include <linux/dcache.h>
23#include <linux/percpu.h>
24#include <linux/ptrace.h>
25#include <linux/reboot.h>
26#include <linux/vmstat.h>
27#include <linux/device.h>
28#include <linux/vmalloc.h>
29#include <linux/hardirq.h>
30#include <linux/rculist.h>
31#include <linux/uaccess.h>
32#include <linux/syscalls.h>
33#include <linux/anon_inodes.h>
34#include <linux/kernel_stat.h>
35#include <linux/perf_event.h>
36#include <linux/ftrace_event.h>
37#include <linux/hw_breakpoint.h>
38
39#include <asm/irq_regs.h>
40
41enum event_type_t {
42    EVENT_FLEXIBLE = 0x1,
43    EVENT_PINNED = 0x2,
44    EVENT_ALL = EVENT_FLEXIBLE | EVENT_PINNED,
45};
46
47atomic_t perf_task_events __read_mostly;
48static atomic_t nr_mmap_events __read_mostly;
49static atomic_t nr_comm_events __read_mostly;
50static atomic_t nr_task_events __read_mostly;
51
52static LIST_HEAD(pmus);
53static DEFINE_MUTEX(pmus_lock);
54static struct srcu_struct pmus_srcu;
55
56/*
57 * perf event paranoia level:
58 * -1 - not paranoid at all
59 * 0 - disallow raw tracepoint access for unpriv
60 * 1 - disallow cpu events for unpriv
61 * 2 - disallow kernel profiling for unpriv
62 */
63int sysctl_perf_event_paranoid __read_mostly = 1;
64
65int sysctl_perf_event_mlock __read_mostly = 512; /* 'free' kb per user */
66
67/*
68 * max perf event sample rate
69 */
70int sysctl_perf_event_sample_rate __read_mostly = 100000;
71
72static atomic64_t perf_event_id;
73
74static void cpu_ctx_sched_out(struct perf_cpu_context *cpuctx,
75                  enum event_type_t event_type);
76
77static void cpu_ctx_sched_in(struct perf_cpu_context *cpuctx,
78                 enum event_type_t event_type);
79
80void __weak perf_event_print_debug(void) { }
81
82extern __weak const char *perf_pmu_name(void)
83{
84    return "pmu";
85}
86
87static inline u64 perf_clock(void)
88{
89    return local_clock();
90}
91
92void perf_pmu_disable(struct pmu *pmu)
93{
94    int *count = this_cpu_ptr(pmu->pmu_disable_count);
95    if (!(*count)++)
96        pmu->pmu_disable(pmu);
97}
98
99void perf_pmu_enable(struct pmu *pmu)
100{
101    int *count = this_cpu_ptr(pmu->pmu_disable_count);
102    if (!--(*count))
103        pmu->pmu_enable(pmu);
104}
105
106static DEFINE_PER_CPU(struct list_head, rotation_list);
107
108/*
109 * perf_pmu_rotate_start() and perf_rotate_context() are fully serialized
110 * because they're strictly cpu affine and rotate_start is called with IRQs
111 * disabled, while rotate_context is called from IRQ context.
112 */
113static void perf_pmu_rotate_start(struct pmu *pmu)
114{
115    struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
116    struct list_head *head = &__get_cpu_var(rotation_list);
117
118    WARN_ON(!irqs_disabled());
119
120    if (list_empty(&cpuctx->rotation_list))
121        list_add(&cpuctx->rotation_list, head);
122}
123
124static void get_ctx(struct perf_event_context *ctx)
125{
126    WARN_ON(!atomic_inc_not_zero(&ctx->refcount));
127}
128
129static void free_ctx(struct rcu_head *head)
130{
131    struct perf_event_context *ctx;
132
133    ctx = container_of(head, struct perf_event_context, rcu_head);
134    kfree(ctx);
135}
136
137static void put_ctx(struct perf_event_context *ctx)
138{
139    if (atomic_dec_and_test(&ctx->refcount)) {
140        if (ctx->parent_ctx)
141            put_ctx(ctx->parent_ctx);
142        if (ctx->task)
143            put_task_struct(ctx->task);
144        call_rcu(&ctx->rcu_head, free_ctx);
145    }
146}
147
148static void unclone_ctx(struct perf_event_context *ctx)
149{
150    if (ctx->parent_ctx) {
151        put_ctx(ctx->parent_ctx);
152        ctx->parent_ctx = NULL;
153    }
154}
155
156static u32 perf_event_pid(struct perf_event *event, struct task_struct *p)
157{
158    /*
159     * only top level events have the pid namespace they were created in
160     */
161    if (event->parent)
162        event = event->parent;
163
164    return task_tgid_nr_ns(p, event->ns);
165}
166
167static u32 perf_event_tid(struct perf_event *event, struct task_struct *p)
168{
169    /*
170     * only top level events have the pid namespace they were created in
171     */
172    if (event->parent)
173        event = event->parent;
174
175    return task_pid_nr_ns(p, event->ns);
176}
177
178/*
179 * If we inherit events we want to return the parent event id
180 * to userspace.
181 */
182static u64 primary_event_id(struct perf_event *event)
183{
184    u64 id = event->id;
185
186    if (event->parent)
187        id = event->parent->id;
188
189    return id;
190}
191
192/*
193 * Get the perf_event_context for a task and lock it.
194 * This has to cope with with the fact that until it is locked,
195 * the context could get moved to another task.
196 */
197static struct perf_event_context *
198perf_lock_task_context(struct task_struct *task, int ctxn, unsigned long *flags)
199{
200    struct perf_event_context *ctx;
201
202    rcu_read_lock();
203retry:
204    ctx = rcu_dereference(task->perf_event_ctxp[ctxn]);
205    if (ctx) {
206        /*
207         * If this context is a clone of another, it might
208         * get swapped for another underneath us by
209         * perf_event_task_sched_out, though the
210         * rcu_read_lock() protects us from any context
211         * getting freed. Lock the context and check if it
212         * got swapped before we could get the lock, and retry
213         * if so. If we locked the right context, then it
214         * can't get swapped on us any more.
215         */
216        raw_spin_lock_irqsave(&ctx->lock, *flags);
217        if (ctx != rcu_dereference(task->perf_event_ctxp[ctxn])) {
218            raw_spin_unlock_irqrestore(&ctx->lock, *flags);
219            goto retry;
220        }
221
222        if (!atomic_inc_not_zero(&ctx->refcount)) {
223            raw_spin_unlock_irqrestore(&ctx->lock, *flags);
224            ctx = NULL;
225        }
226    }
227    rcu_read_unlock();
228    return ctx;
229}
230
231/*
232 * Get the context for a task and increment its pin_count so it
233 * can't get swapped to another task. This also increments its
234 * reference count so that the context can't get freed.
235 */
236static struct perf_event_context *
237perf_pin_task_context(struct task_struct *task, int ctxn)
238{
239    struct perf_event_context *ctx;
240    unsigned long flags;
241
242    ctx = perf_lock_task_context(task, ctxn, &flags);
243    if (ctx) {
244        ++ctx->pin_count;
245        raw_spin_unlock_irqrestore(&ctx->lock, flags);
246    }
247    return ctx;
248}
249
250static void perf_unpin_context(struct perf_event_context *ctx)
251{
252    unsigned long flags;
253
254    raw_spin_lock_irqsave(&ctx->lock, flags);
255    --ctx->pin_count;
256    raw_spin_unlock_irqrestore(&ctx->lock, flags);
257    put_ctx(ctx);
258}
259
260/*
261 * Update the record of the current time in a context.
262 */
263static void update_context_time(struct perf_event_context *ctx)
264{
265    u64 now = perf_clock();
266
267    ctx->time += now - ctx->timestamp;
268    ctx->timestamp = now;
269}
270
271static u64 perf_event_time(struct perf_event *event)
272{
273    struct perf_event_context *ctx = event->ctx;
274    return ctx ? ctx->time : 0;
275}
276
277/*
278 * Update the total_time_enabled and total_time_running fields for a event.
279 */
280static void update_event_times(struct perf_event *event)
281{
282    struct perf_event_context *ctx = event->ctx;
283    u64 run_end;
284
285    if (event->state < PERF_EVENT_STATE_INACTIVE ||
286        event->group_leader->state < PERF_EVENT_STATE_INACTIVE)
287        return;
288
289    if (ctx->is_active)
290        run_end = perf_event_time(event);
291    else
292        run_end = event->tstamp_stopped;
293
294    event->total_time_enabled = run_end - event->tstamp_enabled;
295
296    if (event->state == PERF_EVENT_STATE_INACTIVE)
297        run_end = event->tstamp_stopped;
298    else
299        run_end = perf_event_time(event);
300
301    event->total_time_running = run_end - event->tstamp_running;
302}
303
304/*
305 * Update total_time_enabled and total_time_running for all events in a group.
306 */
307static void update_group_times(struct perf_event *leader)
308{
309    struct perf_event *event;
310
311    update_event_times(leader);
312    list_for_each_entry(event, &leader->sibling_list, group_entry)
313        update_event_times(event);
314}
315
316static struct list_head *
317ctx_group_list(struct perf_event *event, struct perf_event_context *ctx)
318{
319    if (event->attr.pinned)
320        return &ctx->pinned_groups;
321    else
322        return &ctx->flexible_groups;
323}
324
325/*
326 * Add a event from the lists for its context.
327 * Must be called with ctx->mutex and ctx->lock held.
328 */
329static void
330list_add_event(struct perf_event *event, struct perf_event_context *ctx)
331{
332    WARN_ON_ONCE(event->attach_state & PERF_ATTACH_CONTEXT);
333    event->attach_state |= PERF_ATTACH_CONTEXT;
334
335    /*
336     * If we're a stand alone event or group leader, we go to the context
337     * list, group events are kept attached to the group so that
338     * perf_group_detach can, at all times, locate all siblings.
339     */
340    if (event->group_leader == event) {
341        struct list_head *list;
342
343        if (is_software_event(event))
344            event->group_flags |= PERF_GROUP_SOFTWARE;
345
346        list = ctx_group_list(event, ctx);
347        list_add_tail(&event->group_entry, list);
348    }
349
350    list_add_rcu(&event->event_entry, &ctx->event_list);
351    if (!ctx->nr_events)
352        perf_pmu_rotate_start(ctx->pmu);
353    ctx->nr_events++;
354    if (event->attr.inherit_stat)
355        ctx->nr_stat++;
356}
357
358/*
359 * Called at perf_event creation and when events are attached/detached from a
360 * group.
361 */
362static void perf_event__read_size(struct perf_event *event)
363{
364    int entry = sizeof(u64); /* value */
365    int size = 0;
366    int nr = 1;
367
368    if (event->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
369        size += sizeof(u64);
370
371    if (event->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
372        size += sizeof(u64);
373
374    if (event->attr.read_format & PERF_FORMAT_ID)
375        entry += sizeof(u64);
376
377    if (event->attr.read_format & PERF_FORMAT_GROUP) {
378        nr += event->group_leader->nr_siblings;
379        size += sizeof(u64);
380    }
381
382    size += entry * nr;
383    event->read_size = size;
384}
385
386static void perf_event__header_size(struct perf_event *event)
387{
388    struct perf_sample_data *data;
389    u64 sample_type = event->attr.sample_type;
390    u16 size = 0;
391
392    perf_event__read_size(event);
393
394    if (sample_type & PERF_SAMPLE_IP)
395        size += sizeof(data->ip);
396
397    if (sample_type & PERF_SAMPLE_ADDR)
398        size += sizeof(data->addr);
399
400    if (sample_type & PERF_SAMPLE_PERIOD)
401        size += sizeof(data->period);
402
403    if (sample_type & PERF_SAMPLE_READ)
404        size += event->read_size;
405
406    event->header_size = size;
407}
408
409static void perf_event__id_header_size(struct perf_event *event)
410{
411    struct perf_sample_data *data;
412    u64 sample_type = event->attr.sample_type;
413    u16 size = 0;
414
415    if (sample_type & PERF_SAMPLE_TID)
416        size += sizeof(data->tid_entry);
417
418    if (sample_type & PERF_SAMPLE_TIME)
419        size += sizeof(data->time);
420
421    if (sample_type & PERF_SAMPLE_ID)
422        size += sizeof(data->id);
423
424    if (sample_type & PERF_SAMPLE_STREAM_ID)
425        size += sizeof(data->stream_id);
426
427    if (sample_type & PERF_SAMPLE_CPU)
428        size += sizeof(data->cpu_entry);
429
430    event->id_header_size = size;
431}
432
433static void perf_group_attach(struct perf_event *event)
434{
435    struct perf_event *group_leader = event->group_leader, *pos;
436
437    /*
438     * We can have double attach due to group movement in perf_event_open.
439     */
440    if (event->attach_state & PERF_ATTACH_GROUP)
441        return;
442
443    event->attach_state |= PERF_ATTACH_GROUP;
444
445    if (group_leader == event)
446        return;
447
448    if (group_leader->group_flags & PERF_GROUP_SOFTWARE &&
449            !is_software_event(event))
450        group_leader->group_flags &= ~PERF_GROUP_SOFTWARE;
451
452    list_add_tail(&event->group_entry, &group_leader->sibling_list);
453    group_leader->nr_siblings++;
454
455    perf_event__header_size(group_leader);
456
457    list_for_each_entry(pos, &group_leader->sibling_list, group_entry)
458        perf_event__header_size(pos);
459}
460
461/*
462 * Remove a event from the lists for its context.
463 * Must be called with ctx->mutex and ctx->lock held.
464 */
465static void
466list_del_event(struct perf_event *event, struct perf_event_context *ctx)
467{
468    /*
469     * We can have double detach due to exit/hot-unplug + close.
470     */
471    if (!(event->attach_state & PERF_ATTACH_CONTEXT))
472        return;
473
474    event->attach_state &= ~PERF_ATTACH_CONTEXT;
475
476    ctx->nr_events--;
477    if (event->attr.inherit_stat)
478        ctx->nr_stat--;
479
480    list_del_rcu(&event->event_entry);
481
482    if (event->group_leader == event)
483        list_del_init(&event->group_entry);
484
485    update_group_times(event);
486
487    /*
488     * If event was in error state, then keep it
489     * that way, otherwise bogus counts will be
490     * returned on read(). The only way to get out
491     * of error state is by explicit re-enabling
492     * of the event
493     */
494    if (event->state > PERF_EVENT_STATE_OFF)
495        event->state = PERF_EVENT_STATE_OFF;
496}
497
498static void perf_group_detach(struct perf_event *event)
499{
500    struct perf_event *sibling, *tmp;
501    struct list_head *list = NULL;
502
503    /*
504     * We can have double detach due to exit/hot-unplug + close.
505     */
506    if (!(event->attach_state & PERF_ATTACH_GROUP))
507        return;
508
509    event->attach_state &= ~PERF_ATTACH_GROUP;
510
511    /*
512     * If this is a sibling, remove it from its group.
513     */
514    if (event->group_leader != event) {
515        list_del_init(&event->group_entry);
516        event->group_leader->nr_siblings--;
517        goto out;
518    }
519
520    if (!list_empty(&event->group_entry))
521        list = &event->group_entry;
522
523    /*
524     * If this was a group event with sibling events then
525     * upgrade the siblings to singleton events by adding them
526     * to whatever list we are on.
527     */
528    list_for_each_entry_safe(sibling, tmp, &event->sibling_list, group_entry) {
529        if (list)
530            list_move_tail(&sibling->group_entry, list);
531        sibling->group_leader = sibling;
532
533        /* Inherit group flags from the previous leader */
534        sibling->group_flags = event->group_flags;
535    }
536
537out:
538    perf_event__header_size(event->group_leader);
539
540    list_for_each_entry(tmp, &event->group_leader->sibling_list, group_entry)
541        perf_event__header_size(tmp);
542}
543
544static inline int
545event_filter_match(struct perf_event *event)
546{
547    return event->cpu == -1 || event->cpu == smp_processor_id();
548}
549
550static void
551event_sched_out(struct perf_event *event,
552          struct perf_cpu_context *cpuctx,
553          struct perf_event_context *ctx)
554{
555    u64 tstamp = perf_event_time(event);
556    u64 delta;
557    /*
558     * An event which could not be activated because of
559     * filter mismatch still needs to have its timings
560     * maintained, otherwise bogus information is return
561     * via read() for time_enabled, time_running:
562     */
563    if (event->state == PERF_EVENT_STATE_INACTIVE
564        && !event_filter_match(event)) {
565        delta = ctx->time - event->tstamp_stopped;
566        event->tstamp_running += delta;
567        event->tstamp_stopped = tstamp;
568    }
569
570    if (event->state != PERF_EVENT_STATE_ACTIVE)
571        return;
572
573    event->state = PERF_EVENT_STATE_INACTIVE;
574    if (event->pending_disable) {
575        event->pending_disable = 0;
576        event->state = PERF_EVENT_STATE_OFF;
577    }
578    event->tstamp_stopped = tstamp;
579    event->pmu->del(event, 0);
580    event->oncpu = -1;
581
582    if (!is_software_event(event))
583        cpuctx->active_oncpu--;
584    ctx->nr_active--;
585    if (event->attr.exclusive || !cpuctx->active_oncpu)
586        cpuctx->exclusive = 0;
587}
588
589static void
590group_sched_out(struct perf_event *group_event,
591        struct perf_cpu_context *cpuctx,
592        struct perf_event_context *ctx)
593{
594    struct perf_event *event;
595    int state = group_event->state;
596
597    event_sched_out(group_event, cpuctx, ctx);
598
599    /*
600     * Schedule out siblings (if any):
601     */
602    list_for_each_entry(event, &group_event->sibling_list, group_entry)
603        event_sched_out(event, cpuctx, ctx);
604
605    if (state == PERF_EVENT_STATE_ACTIVE && group_event->attr.exclusive)
606        cpuctx->exclusive = 0;
607}
608
609static inline struct perf_cpu_context *
610__get_cpu_context(struct perf_event_context *ctx)
611{
612    return this_cpu_ptr(ctx->pmu->pmu_cpu_context);
613}
614
615/*
616 * Cross CPU call to remove a performance event
617 *
618 * We disable the event on the hardware level first. After that we
619 * remove it from the context list.
620 */
621static void __perf_event_remove_from_context(void *info)
622{
623    struct perf_event *event = info;
624    struct perf_event_context *ctx = event->ctx;
625    struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
626
627    /*
628     * If this is a task context, we need to check whether it is
629     * the current task context of this cpu. If not it has been
630     * scheduled out before the smp call arrived.
631     */
632    if (ctx->task && cpuctx->task_ctx != ctx)
633        return;
634
635    raw_spin_lock(&ctx->lock);
636
637    event_sched_out(event, cpuctx, ctx);
638
639    list_del_event(event, ctx);
640
641    raw_spin_unlock(&ctx->lock);
642}
643
644
645/*
646 * Remove the event from a task's (or a CPU's) list of events.
647 *
648 * Must be called with ctx->mutex held.
649 *
650 * CPU events are removed with a smp call. For task events we only
651 * call when the task is on a CPU.
652 *
653 * If event->ctx is a cloned context, callers must make sure that
654 * every task struct that event->ctx->task could possibly point to
655 * remains valid. This is OK when called from perf_release since
656 * that only calls us on the top-level context, which can't be a clone.
657 * When called from perf_event_exit_task, it's OK because the
658 * context has been detached from its task.
659 */
660static void perf_event_remove_from_context(struct perf_event *event)
661{
662    struct perf_event_context *ctx = event->ctx;
663    struct task_struct *task = ctx->task;
664
665    if (!task) {
666        /*
667         * Per cpu events are removed via an smp call and
668         * the removal is always successful.
669         */
670        smp_call_function_single(event->cpu,
671                     __perf_event_remove_from_context,
672                     event, 1);
673        return;
674    }
675
676retry:
677    task_oncpu_function_call(task, __perf_event_remove_from_context,
678                 event);
679
680    raw_spin_lock_irq(&ctx->lock);
681    /*
682     * If the context is active we need to retry the smp call.
683     */
684    if (ctx->nr_active && !list_empty(&event->group_entry)) {
685        raw_spin_unlock_irq(&ctx->lock);
686        goto retry;
687    }
688
689    /*
690     * The lock prevents that this context is scheduled in so we
691     * can remove the event safely, if the call above did not
692     * succeed.
693     */
694    if (!list_empty(&event->group_entry))
695        list_del_event(event, ctx);
696    raw_spin_unlock_irq(&ctx->lock);
697}
698
699/*
700 * Cross CPU call to disable a performance event
701 */
702static void __perf_event_disable(void *info)
703{
704    struct perf_event *event = info;
705    struct perf_event_context *ctx = event->ctx;
706    struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
707
708    /*
709     * If this is a per-task event, need to check whether this
710     * event's task is the current task on this cpu.
711     */
712    if (ctx->task && cpuctx->task_ctx != ctx)
713        return;
714
715    raw_spin_lock(&ctx->lock);
716
717    /*
718     * If the event is on, turn it off.
719     * If it is in error state, leave it in error state.
720     */
721    if (event->state >= PERF_EVENT_STATE_INACTIVE) {
722        update_context_time(ctx);
723        update_group_times(event);
724        if (event == event->group_leader)
725            group_sched_out(event, cpuctx, ctx);
726        else
727            event_sched_out(event, cpuctx, ctx);
728        event->state = PERF_EVENT_STATE_OFF;
729    }
730
731    raw_spin_unlock(&ctx->lock);
732}
733
734/*
735 * Disable a event.
736 *
737 * If event->ctx is a cloned context, callers must make sure that
738 * every task struct that event->ctx->task could possibly point to
739 * remains valid. This condition is satisifed when called through
740 * perf_event_for_each_child or perf_event_for_each because they
741 * hold the top-level event's child_mutex, so any descendant that
742 * goes to exit will block in sync_child_event.
743 * When called from perf_pending_event it's OK because event->ctx
744 * is the current context on this CPU and preemption is disabled,
745 * hence we can't get into perf_event_task_sched_out for this context.
746 */
747void perf_event_disable(struct perf_event *event)
748{
749    struct perf_event_context *ctx = event->ctx;
750    struct task_struct *task = ctx->task;
751
752    if (!task) {
753        /*
754         * Disable the event on the cpu that it's on
755         */
756        smp_call_function_single(event->cpu, __perf_event_disable,
757                     event, 1);
758        return;
759    }
760
761retry:
762    task_oncpu_function_call(task, __perf_event_disable, event);
763
764    raw_spin_lock_irq(&ctx->lock);
765    /*
766     * If the event is still active, we need to retry the cross-call.
767     */
768    if (event->state == PERF_EVENT_STATE_ACTIVE) {
769        raw_spin_unlock_irq(&ctx->lock);
770        goto retry;
771    }
772
773    /*
774     * Since we have the lock this context can't be scheduled
775     * in, so we can change the state safely.
776     */
777    if (event->state == PERF_EVENT_STATE_INACTIVE) {
778        update_group_times(event);
779        event->state = PERF_EVENT_STATE_OFF;
780    }
781
782    raw_spin_unlock_irq(&ctx->lock);
783}
784
785#define MAX_INTERRUPTS (~0ULL)
786
787static void perf_log_throttle(struct perf_event *event, int enable);
788
789static int
790event_sched_in(struct perf_event *event,
791         struct perf_cpu_context *cpuctx,
792         struct perf_event_context *ctx)
793{
794    u64 tstamp = perf_event_time(event);
795
796    if (event->state <= PERF_EVENT_STATE_OFF)
797        return 0;
798
799    event->state = PERF_EVENT_STATE_ACTIVE;
800    event->oncpu = smp_processor_id();
801
802    /*
803     * Unthrottle events, since we scheduled we might have missed several
804     * ticks already, also for a heavily scheduling task there is little
805     * guarantee it'll get a tick in a timely manner.
806     */
807    if (unlikely(event->hw.interrupts == MAX_INTERRUPTS)) {
808        perf_log_throttle(event, 1);
809        event->hw.interrupts = 0;
810    }
811
812    /*
813     * The new state must be visible before we turn it on in the hardware:
814     */
815    smp_wmb();
816
817    if (event->pmu->add(event, PERF_EF_START)) {
818        event->state = PERF_EVENT_STATE_INACTIVE;
819        event->oncpu = -1;
820        return -EAGAIN;
821    }
822
823    event->tstamp_running += tstamp - event->tstamp_stopped;
824
825    event->shadow_ctx_time = tstamp - ctx->timestamp;
826
827    if (!is_software_event(event))
828        cpuctx->active_oncpu++;
829    ctx->nr_active++;
830
831    if (event->attr.exclusive)
832        cpuctx->exclusive = 1;
833
834    return 0;
835}
836
837static int
838group_sched_in(struct perf_event *group_event,
839           struct perf_cpu_context *cpuctx,
840           struct perf_event_context *ctx)
841{
842    struct perf_event *event, *partial_group = NULL;
843    struct pmu *pmu = group_event->pmu;
844    u64 now = ctx->time;
845    bool simulate = false;
846
847    if (group_event->state == PERF_EVENT_STATE_OFF)
848        return 0;
849
850    pmu->start_txn(pmu);
851
852    if (event_sched_in(group_event, cpuctx, ctx)) {
853        pmu->cancel_txn(pmu);
854        return -EAGAIN;
855    }
856
857    /*
858     * Schedule in siblings as one group (if any):
859     */
860    list_for_each_entry(event, &group_event->sibling_list, group_entry) {
861        if (event_sched_in(event, cpuctx, ctx)) {
862            partial_group = event;
863            goto group_error;
864        }
865    }
866
867    if (!pmu->commit_txn(pmu))
868        return 0;
869
870group_error:
871    /*
872     * Groups can be scheduled in as one unit only, so undo any
873     * partial group before returning:
874     * The events up to the failed event are scheduled out normally,
875     * tstamp_stopped will be updated.
876     *
877     * The failed events and the remaining siblings need to have
878     * their timings updated as if they had gone thru event_sched_in()
879     * and event_sched_out(). This is required to get consistent timings
880     * across the group. This also takes care of the case where the group
881     * could never be scheduled by ensuring tstamp_stopped is set to mark
882     * the time the event was actually stopped, such that time delta
883     * calculation in update_event_times() is correct.
884     */
885    list_for_each_entry(event, &group_event->sibling_list, group_entry) {
886        if (event == partial_group)
887            simulate = true;
888
889        if (simulate) {
890            event->tstamp_running += now - event->tstamp_stopped;
891            event->tstamp_stopped = now;
892        } else {
893            event_sched_out(event, cpuctx, ctx);
894        }
895    }
896    event_sched_out(group_event, cpuctx, ctx);
897
898    pmu->cancel_txn(pmu);
899
900    return -EAGAIN;
901}
902
903/*
904 * Work out whether we can put this event group on the CPU now.
905 */
906static int group_can_go_on(struct perf_event *event,
907               struct perf_cpu_context *cpuctx,
908               int can_add_hw)
909{
910    /*
911     * Groups consisting entirely of software events can always go on.
912     */
913    if (event->group_flags & PERF_GROUP_SOFTWARE)
914        return 1;
915    /*
916     * If an exclusive group is already on, no other hardware
917     * events can go on.
918     */
919    if (cpuctx->exclusive)
920        return 0;
921    /*
922     * If this group is exclusive and there are already
923     * events on the CPU, it can't go on.
924     */
925    if (event->attr.exclusive && cpuctx->active_oncpu)
926        return 0;
927    /*
928     * Otherwise, try to add it if all previous groups were able
929     * to go on.
930     */
931    return can_add_hw;
932}
933
934static void add_event_to_ctx(struct perf_event *event,
935                   struct perf_event_context *ctx)
936{
937    u64 tstamp = perf_event_time(event);
938
939    list_add_event(event, ctx);
940    perf_group_attach(event);
941    event->tstamp_enabled = tstamp;
942    event->tstamp_running = tstamp;
943    event->tstamp_stopped = tstamp;
944}
945
946/*
947 * Cross CPU call to install and enable a performance event
948 *
949 * Must be called with ctx->mutex held
950 */
951static void __perf_install_in_context(void *info)
952{
953    struct perf_event *event = info;
954    struct perf_event_context *ctx = event->ctx;
955    struct perf_event *leader = event->group_leader;
956    struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
957    int err;
958
959    /*
960     * If this is a task context, we need to check whether it is
961     * the current task context of this cpu. If not it has been
962     * scheduled out before the smp call arrived.
963     * Or possibly this is the right context but it isn't
964     * on this cpu because it had no events.
965     */
966    if (ctx->task && cpuctx->task_ctx != ctx) {
967        if (cpuctx->task_ctx || ctx->task != current)
968            return;
969        cpuctx->task_ctx = ctx;
970    }
971
972    raw_spin_lock(&ctx->lock);
973    ctx->is_active = 1;
974    update_context_time(ctx);
975
976    add_event_to_ctx(event, ctx);
977
978    if (!event_filter_match(event))
979        goto unlock;
980
981    /*
982     * Don't put the event on if it is disabled or if
983     * it is in a group and the group isn't on.
984     */
985    if (event->state != PERF_EVENT_STATE_INACTIVE ||
986        (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE))
987        goto unlock;
988
989    /*
990     * An exclusive event can't go on if there are already active
991     * hardware events, and no hardware event can go on if there
992     * is already an exclusive event on.
993     */
994    if (!group_can_go_on(event, cpuctx, 1))
995        err = -EEXIST;
996    else
997        err = event_sched_in(event, cpuctx, ctx);
998
999    if (err) {
1000        /*
1001         * This event couldn't go on. If it is in a group
1002         * then we have to pull the whole group off.
1003         * If the event group is pinned then put it in error state.
1004         */
1005        if (leader != event)
1006            group_sched_out(leader, cpuctx, ctx);
1007        if (leader->attr.pinned) {
1008            update_group_times(leader);
1009            leader->state = PERF_EVENT_STATE_ERROR;
1010        }
1011    }
1012
1013unlock:
1014    raw_spin_unlock(&ctx->lock);
1015}
1016
1017/*
1018 * Attach a performance event to a context
1019 *
1020 * First we add the event to the list with the hardware enable bit
1021 * in event->hw_config cleared.
1022 *
1023 * If the event is attached to a task which is on a CPU we use a smp
1024 * call to enable it in the task context. The task might have been
1025 * scheduled away, but we check this in the smp call again.
1026 *
1027 * Must be called with ctx->mutex held.
1028 */
1029static void
1030perf_install_in_context(struct perf_event_context *ctx,
1031            struct perf_event *event,
1032            int cpu)
1033{
1034    struct task_struct *task = ctx->task;
1035
1036    event->ctx = ctx;
1037
1038    if (!task) {
1039        /*
1040         * Per cpu events are installed via an smp call and
1041         * the install is always successful.
1042         */
1043        smp_call_function_single(cpu, __perf_install_in_context,
1044                     event, 1);
1045        return;
1046    }
1047
1048retry:
1049    task_oncpu_function_call(task, __perf_install_in_context,
1050                 event);
1051
1052    raw_spin_lock_irq(&ctx->lock);
1053    /*
1054     * we need to retry the smp call.
1055     */
1056    if (ctx->is_active && list_empty(&event->group_entry)) {
1057        raw_spin_unlock_irq(&ctx->lock);
1058        goto retry;
1059    }
1060
1061    /*
1062     * The lock prevents that this context is scheduled in so we
1063     * can add the event safely, if it the call above did not
1064     * succeed.
1065     */
1066    if (list_empty(&event->group_entry))
1067        add_event_to_ctx(event, ctx);
1068    raw_spin_unlock_irq(&ctx->lock);
1069}
1070
1071/*
1072 * Put a event into inactive state and update time fields.
1073 * Enabling the leader of a group effectively enables all
1074 * the group members that aren't explicitly disabled, so we
1075 * have to update their ->tstamp_enabled also.
1076 * Note: this works for group members as well as group leaders
1077 * since the non-leader members' sibling_lists will be empty.
1078 */
1079static void __perf_event_mark_enabled(struct perf_event *event,
1080                    struct perf_event_context *ctx)
1081{
1082    struct perf_event *sub;
1083    u64 tstamp = perf_event_time(event);
1084
1085    event->state = PERF_EVENT_STATE_INACTIVE;
1086    event->tstamp_enabled = tstamp - event->total_time_enabled;
1087    list_for_each_entry(sub, &event->sibling_list, group_entry) {
1088        if (sub->state >= PERF_EVENT_STATE_INACTIVE)
1089            sub->tstamp_enabled = tstamp - sub->total_time_enabled;
1090    }
1091}
1092
1093/*
1094 * Cross CPU call to enable a performance event
1095 */
1096static void __perf_event_enable(void *info)
1097{
1098    struct perf_event *event = info;
1099    struct perf_event_context *ctx = event->ctx;
1100    struct perf_event *leader = event->group_leader;
1101    struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
1102    int err;
1103
1104    /*
1105     * If this is a per-task event, need to check whether this
1106     * event's task is the current task on this cpu.
1107     */
1108    if (ctx->task && cpuctx->task_ctx != ctx) {
1109        if (cpuctx->task_ctx || ctx->task != current)
1110            return;
1111        cpuctx->task_ctx = ctx;
1112    }
1113
1114    raw_spin_lock(&ctx->lock);
1115    ctx->is_active = 1;
1116    update_context_time(ctx);
1117
1118    if (event->state >= PERF_EVENT_STATE_INACTIVE)
1119        goto unlock;
1120    __perf_event_mark_enabled(event, ctx);
1121
1122    if (!event_filter_match(event))
1123        goto unlock;
1124
1125    /*
1126     * If the event is in a group and isn't the group leader,
1127     * then don't put it on unless the group is on.
1128     */
1129    if (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE)
1130        goto unlock;
1131
1132    if (!group_can_go_on(event, cpuctx, 1)) {
1133        err = -EEXIST;
1134    } else {
1135        if (event == leader)
1136            err = group_sched_in(event, cpuctx, ctx);
1137        else
1138            err = event_sched_in(event, cpuctx, ctx);
1139    }
1140
1141    if (err) {
1142        /*
1143         * If this event can't go on and it's part of a
1144         * group, then the whole group has to come off.
1145         */
1146        if (leader != event)
1147            group_sched_out(leader, cpuctx, ctx);
1148        if (leader->attr.pinned) {
1149            update_group_times(leader);
1150            leader->state = PERF_EVENT_STATE_ERROR;
1151        }
1152    }
1153
1154unlock:
1155    raw_spin_unlock(&ctx->lock);
1156}
1157
1158/*
1159 * Enable a event.
1160 *
1161 * If event->ctx is a cloned context, callers must make sure that
1162 * every task struct that event->ctx->task could possibly point to
1163 * remains valid. This condition is satisfied when called through
1164 * perf_event_for_each_child or perf_event_for_each as described
1165 * for perf_event_disable.
1166 */
1167void perf_event_enable(struct perf_event *event)
1168{
1169    struct perf_event_context *ctx = event->ctx;
1170    struct task_struct *task = ctx->task;
1171
1172    if (!task) {
1173        /*
1174         * Enable the event on the cpu that it's on
1175         */
1176        smp_call_function_single(event->cpu, __perf_event_enable,
1177                     event, 1);
1178        return;
1179    }
1180
1181    raw_spin_lock_irq(&ctx->lock);
1182    if (event->state >= PERF_EVENT_STATE_INACTIVE)
1183        goto out;
1184
1185    /*
1186     * If the event is in error state, clear that first.
1187     * That way, if we see the event in error state below, we
1188     * know that it has gone back into error state, as distinct
1189     * from the task having been scheduled away before the
1190     * cross-call arrived.
1191     */
1192    if (event->state == PERF_EVENT_STATE_ERROR)
1193        event->state = PERF_EVENT_STATE_OFF;
1194
1195retry:
1196    raw_spin_unlock_irq(&ctx->lock);
1197    task_oncpu_function_call(task, __perf_event_enable, event);
1198
1199    raw_spin_lock_irq(&ctx->lock);
1200
1201    /*
1202     * If the context is active and the event is still off,
1203     * we need to retry the cross-call.
1204     */
1205    if (ctx->is_active && event->state == PERF_EVENT_STATE_OFF)
1206        goto retry;
1207
1208    /*
1209     * Since we have the lock this context can't be scheduled
1210     * in, so we can change the state safely.
1211     */
1212    if (event->state == PERF_EVENT_STATE_OFF)
1213        __perf_event_mark_enabled(event, ctx);
1214
1215out:
1216    raw_spin_unlock_irq(&ctx->lock);
1217}
1218
1219static int perf_event_refresh(struct perf_event *event, int refresh)
1220{
1221    /*
1222     * not supported on inherited events
1223     */
1224    if (event->attr.inherit || !is_sampling_event(event))
1225        return -EINVAL;
1226
1227    atomic_add(refresh, &event->event_limit);
1228    perf_event_enable(event);
1229
1230    return 0;
1231}
1232
1233static void ctx_sched_out(struct perf_event_context *ctx,
1234              struct perf_cpu_context *cpuctx,
1235              enum event_type_t event_type)
1236{
1237    struct perf_event *event;
1238
1239    raw_spin_lock(&ctx->lock);
1240    perf_pmu_disable(ctx->pmu);
1241    ctx->is_active = 0;
1242    if (likely(!ctx->nr_events))
1243        goto out;
1244    update_context_time(ctx);
1245
1246    if (!ctx->nr_active)
1247        goto out;
1248
1249    if (event_type & EVENT_PINNED) {
1250        list_for_each_entry(event, &ctx->pinned_groups, group_entry)
1251            group_sched_out(event, cpuctx, ctx);
1252    }
1253
1254    if (event_type & EVENT_FLEXIBLE) {
1255        list_for_each_entry(event, &ctx->flexible_groups, group_entry)
1256            group_sched_out(event, cpuctx, ctx);
1257    }
1258out:
1259    perf_pmu_enable(ctx->pmu);
1260    raw_spin_unlock(&ctx->lock);
1261}
1262
1263/*
1264 * Test whether two contexts are equivalent, i.e. whether they
1265 * have both been cloned from the same version of the same context
1266 * and they both have the same number of enabled events.
1267 * If the number of enabled events is the same, then the set
1268 * of enabled events should be the same, because these are both
1269 * inherited contexts, therefore we can't access individual events
1270 * in them directly with an fd; we can only enable/disable all
1271 * events via prctl, or enable/disable all events in a family
1272 * via ioctl, which will have the same effect on both contexts.
1273 */
1274static int context_equiv(struct perf_event_context *ctx1,
1275             struct perf_event_context *ctx2)
1276{
1277    return ctx1->parent_ctx && ctx1->parent_ctx == ctx2->parent_ctx
1278        && ctx1->parent_gen == ctx2->parent_gen
1279        && !ctx1->pin_count && !ctx2->pin_count;
1280}
1281
1282static void __perf_event_sync_stat(struct perf_event *event,
1283                     struct perf_event *next_event)
1284{
1285    u64 value;
1286
1287    if (!event->attr.inherit_stat)
1288        return;
1289
1290    /*
1291     * Update the event value, we cannot use perf_event_read()
1292     * because we're in the middle of a context switch and have IRQs
1293     * disabled, which upsets smp_call_function_single(), however
1294     * we know the event must be on the current CPU, therefore we
1295     * don't need to use it.
1296     */
1297    switch (event->state) {
1298    case PERF_EVENT_STATE_ACTIVE:
1299        event->pmu->read(event);
1300        /* fall-through */
1301
1302    case PERF_EVENT_STATE_INACTIVE:
1303        update_event_times(event);
1304        break;
1305
1306    default:
1307        break;
1308    }
1309
1310    /*
1311     * In order to keep per-task stats reliable we need to flip the event
1312     * values when we flip the contexts.
1313     */
1314    value = local64_read(&next_event->count);
1315    value = local64_xchg(&event->count, value);
1316    local64_set(&next_event->count, value);
1317
1318    swap(event->total_time_enabled, next_event->total_time_enabled);
1319    swap(event->total_time_running, next_event->total_time_running);
1320
1321    /*
1322     * Since we swizzled the values, update the user visible data too.
1323     */
1324    perf_event_update_userpage(event);
1325    perf_event_update_userpage(next_event);
1326}
1327
1328#define list_next_entry(pos, member) \
1329    list_entry(pos->member.next, typeof(*pos), member)
1330
1331static void perf_event_sync_stat(struct perf_event_context *ctx,
1332                   struct perf_event_context *next_ctx)
1333{
1334    struct perf_event *event, *next_event;
1335
1336    if (!ctx->nr_stat)
1337        return;
1338
1339    update_context_time(ctx);
1340
1341    event = list_first_entry(&ctx->event_list,
1342                   struct perf_event, event_entry);
1343
1344    next_event = list_first_entry(&next_ctx->event_list,
1345                    struct perf_event, event_entry);
1346
1347    while (&event->event_entry != &ctx->event_list &&
1348           &next_event->event_entry != &next_ctx->event_list) {
1349
1350        __perf_event_sync_stat(event, next_event);
1351
1352        event = list_next_entry(event, event_entry);
1353        next_event = list_next_entry(next_event, event_entry);
1354    }
1355}
1356
1357void perf_event_context_sched_out(struct task_struct *task, int ctxn,
1358                  struct task_struct *next)
1359{
1360    struct perf_event_context *ctx = task->perf_event_ctxp[ctxn];
1361    struct perf_event_context *next_ctx;
1362    struct perf_event_context *parent;
1363    struct perf_cpu_context *cpuctx;
1364    int do_switch = 1;
1365
1366    if (likely(!ctx))
1367        return;
1368
1369    cpuctx = __get_cpu_context(ctx);
1370    if (!cpuctx->task_ctx)
1371        return;
1372
1373    rcu_read_lock();
1374    parent = rcu_dereference(ctx->parent_ctx);
1375    next_ctx = next->perf_event_ctxp[ctxn];
1376    if (parent && next_ctx &&
1377        rcu_dereference(next_ctx->parent_ctx) == parent) {
1378        /*
1379         * Looks like the two contexts are clones, so we might be
1380         * able to optimize the context switch. We lock both
1381         * contexts and check that they are clones under the
1382         * lock (including re-checking that neither has been
1383         * uncloned in the meantime). It doesn't matter which
1384         * order we take the locks because no other cpu could
1385         * be trying to lock both of these tasks.
1386         */
1387        raw_spin_lock(&ctx->lock);
1388        raw_spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING);
1389        if (context_equiv(ctx, next_ctx)) {
1390            /*
1391             * XXX do we need a memory barrier of sorts
1392             * wrt to rcu_dereference() of perf_event_ctxp
1393             */
1394            task->perf_event_ctxp[ctxn] = next_ctx;
1395            next->perf_event_ctxp[ctxn] = ctx;
1396            ctx->task = next;
1397            next_ctx->task = task;
1398            do_switch = 0;
1399
1400            perf_event_sync_stat(ctx, next_ctx);
1401        }
1402        raw_spin_unlock(&next_ctx->lock);
1403        raw_spin_unlock(&ctx->lock);
1404    }
1405    rcu_read_unlock();
1406
1407    if (do_switch) {
1408        ctx_sched_out(ctx, cpuctx, EVENT_ALL);
1409        cpuctx->task_ctx = NULL;
1410    }
1411}
1412
1413#define for_each_task_context_nr(ctxn) \
1414    for ((ctxn) = 0; (ctxn) < perf_nr_task_contexts; (ctxn)++)
1415
1416/*
1417 * Called from scheduler to remove the events of the current task,
1418 * with interrupts disabled.
1419 *
1420 * We stop each event and update the event value in event->count.
1421 *
1422 * This does not protect us against NMI, but disable()
1423 * sets the disabled bit in the control field of event _before_
1424 * accessing the event control register. If a NMI hits, then it will
1425 * not restart the event.
1426 */
1427void __perf_event_task_sched_out(struct task_struct *task,
1428                 struct task_struct *next)
1429{
1430    int ctxn;
1431
1432    for_each_task_context_nr(ctxn)
1433        perf_event_context_sched_out(task, ctxn, next);
1434}
1435
1436static void task_ctx_sched_out(struct perf_event_context *ctx,
1437                   enum event_type_t event_type)
1438{
1439    struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
1440
1441    if (!cpuctx->task_ctx)
1442        return;
1443
1444    if (WARN_ON_ONCE(ctx != cpuctx->task_ctx))
1445        return;
1446
1447    ctx_sched_out(ctx, cpuctx, event_type);
1448    cpuctx->task_ctx = NULL;
1449}
1450
1451/*
1452 * Called with IRQs disabled
1453 */
1454static void cpu_ctx_sched_out(struct perf_cpu_context *cpuctx,
1455                  enum event_type_t event_type)
1456{
1457    ctx_sched_out(&cpuctx->ctx, cpuctx, event_type);
1458}
1459
1460static void
1461ctx_pinned_sched_in(struct perf_event_context *ctx,
1462            struct perf_cpu_context *cpuctx)
1463{
1464    struct perf_event *event;
1465
1466    list_for_each_entry(event, &ctx->pinned_groups, group_entry) {
1467        if (event->state <= PERF_EVENT_STATE_OFF)
1468            continue;
1469        if (!event_filter_match(event))
1470            continue;
1471
1472        if (group_can_go_on(event, cpuctx, 1))
1473            group_sched_in(event, cpuctx, ctx);
1474
1475        /*
1476         * If this pinned group hasn't been scheduled,
1477         * put it in error state.
1478         */
1479        if (event->state == PERF_EVENT_STATE_INACTIVE) {
1480            update_group_times(event);
1481            event->state = PERF_EVENT_STATE_ERROR;
1482        }
1483    }
1484}
1485
1486static void
1487ctx_flexible_sched_in(struct perf_event_context *ctx,
1488              struct perf_cpu_context *cpuctx)
1489{
1490    struct perf_event *event;
1491    int can_add_hw = 1;
1492
1493    list_for_each_entry(event, &ctx->flexible_groups, group_entry) {
1494        /* Ignore events in OFF or ERROR state */
1495        if (event->state <= PERF_EVENT_STATE_OFF)
1496            continue;
1497        /*
1498         * Listen to the 'cpu' scheduling filter constraint
1499         * of events:
1500         */
1501        if (!event_filter_match(event))
1502            continue;
1503
1504        if (group_can_go_on(event, cpuctx, can_add_hw)) {
1505            if (group_sched_in(event, cpuctx, ctx))
1506                can_add_hw = 0;
1507        }
1508    }
1509}
1510
1511static void
1512ctx_sched_in(struct perf_event_context *ctx,
1513         struct perf_cpu_context *cpuctx,
1514         enum event_type_t event_type)
1515{
1516    raw_spin_lock(&ctx->lock);
1517    ctx->is_active = 1;
1518    if (likely(!ctx->nr_events))
1519        goto out;
1520
1521    ctx->timestamp = perf_clock();
1522
1523    /*
1524     * First go through the list and put on any pinned groups
1525     * in order to give them the best chance of going on.
1526     */
1527    if (event_type & EVENT_PINNED)
1528        ctx_pinned_sched_in(ctx, cpuctx);
1529
1530    /* Then walk through the lower prio flexible groups */
1531    if (event_type & EVENT_FLEXIBLE)
1532        ctx_flexible_sched_in(ctx, cpuctx);
1533
1534out:
1535    raw_spin_unlock(&ctx->lock);
1536}
1537
1538static void cpu_ctx_sched_in(struct perf_cpu_context *cpuctx,
1539                 enum event_type_t event_type)
1540{
1541    struct perf_event_context *ctx = &cpuctx->ctx;
1542
1543    ctx_sched_in(ctx, cpuctx, event_type);
1544}
1545
1546static void task_ctx_sched_in(struct perf_event_context *ctx,
1547                  enum event_type_t event_type)
1548{
1549    struct perf_cpu_context *cpuctx;
1550
1551           cpuctx = __get_cpu_context(ctx);
1552    if (cpuctx->task_ctx == ctx)
1553        return;
1554
1555    ctx_sched_in(ctx, cpuctx, event_type);
1556    cpuctx->task_ctx = ctx;
1557}
1558
1559void perf_event_context_sched_in(struct perf_event_context *ctx)
1560{
1561    struct perf_cpu_context *cpuctx;
1562
1563    cpuctx = __get_cpu_context(ctx);
1564    if (cpuctx->task_ctx == ctx)
1565        return;
1566
1567    perf_pmu_disable(ctx->pmu);
1568    /*
1569     * We want to keep the following priority order:
1570     * cpu pinned (that don't need to move), task pinned,
1571     * cpu flexible, task flexible.
1572     */
1573    cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
1574
1575    ctx_sched_in(ctx, cpuctx, EVENT_PINNED);
1576    cpu_ctx_sched_in(cpuctx, EVENT_FLEXIBLE);
1577    ctx_sched_in(ctx, cpuctx, EVENT_FLEXIBLE);
1578
1579    cpuctx->task_ctx = ctx;
1580
1581    /*
1582     * Since these rotations are per-cpu, we need to ensure the
1583     * cpu-context we got scheduled on is actually rotating.
1584     */
1585    perf_pmu_rotate_start(ctx->pmu);
1586    perf_pmu_enable(ctx->pmu);
1587}
1588
1589/*
1590 * Called from scheduler to add the events of the current task
1591 * with interrupts disabled.
1592 *
1593 * We restore the event value and then enable it.
1594 *
1595 * This does not protect us against NMI, but enable()
1596 * sets the enabled bit in the control field of event _before_
1597 * accessing the event control register. If a NMI hits, then it will
1598 * keep the event running.
1599 */
1600void __perf_event_task_sched_in(struct task_struct *task)
1601{
1602    struct perf_event_context *ctx;
1603    int ctxn;
1604
1605    for_each_task_context_nr(ctxn) {
1606        ctx = task->perf_event_ctxp[ctxn];
1607        if (likely(!ctx))
1608            continue;
1609
1610        perf_event_context_sched_in(ctx);
1611    }
1612}
1613
1614static u64 perf_calculate_period(struct perf_event *event, u64 nsec, u64 count)
1615{
1616    u64 frequency = event->attr.sample_freq;
1617    u64 sec = NSEC_PER_SEC;
1618    u64 divisor, dividend;
1619
1620    int count_fls, nsec_fls, frequency_fls, sec_fls;
1621
1622    count_fls = fls64(count);
1623    nsec_fls = fls64(nsec);
1624    frequency_fls = fls64(frequency);
1625    sec_fls = 30;
1626
1627    /*
1628     * We got @count in @nsec, with a target of sample_freq HZ
1629     * the target period becomes:
1630     *
1631     * @count * 10^9
1632     * period = -------------------
1633     * @nsec * sample_freq
1634     *
1635     */
1636
1637    /*
1638     * Reduce accuracy by one bit such that @a and @b converge
1639     * to a similar magnitude.
1640     */
1641#define REDUCE_FLS(a, b) \
1642do { \
1643    if (a##_fls > b##_fls) { \
1644        a >>= 1; \
1645        a##_fls--; \
1646    } else { \
1647        b >>= 1; \
1648        b##_fls--; \
1649    } \
1650} while (0)
1651
1652    /*
1653     * Reduce accuracy until either term fits in a u64, then proceed with
1654     * the other, so that finally we can do a u64/u64 division.
1655     */
1656    while (count_fls + sec_fls > 64 && nsec_fls + frequency_fls > 64) {
1657        REDUCE_FLS(nsec, frequency);
1658        REDUCE_FLS(sec, count);
1659    }
1660
1661    if (count_fls + sec_fls > 64) {
1662        divisor = nsec * frequency;
1663
1664        while (count_fls + sec_fls > 64) {
1665            REDUCE_FLS(count, sec);
1666            divisor >>= 1;
1667        }
1668
1669        dividend = count * sec;
1670    } else {
1671        dividend = count * sec;
1672
1673        while (nsec_fls + frequency_fls > 64) {
1674            REDUCE_FLS(nsec, frequency);
1675            dividend >>= 1;
1676        }
1677
1678        divisor = nsec * frequency;
1679    }
1680
1681    if (!divisor)
1682        return dividend;
1683
1684    return div64_u64(dividend, divisor);
1685}
1686
1687static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count)
1688{
1689    struct hw_perf_event *hwc = &event->hw;
1690    s64 period, sample_period;
1691    s64 delta;
1692
1693    period = perf_calculate_period(event, nsec, count);
1694
1695    delta = (s64)(period - hwc->sample_period);
1696    delta = (delta + 7) / 8; /* low pass filter */
1697
1698    sample_period = hwc->sample_period + delta;
1699
1700    if (!sample_period)
1701        sample_period = 1;
1702
1703    hwc->sample_period = sample_period;
1704
1705    if (local64_read(&hwc->period_left) > 8*sample_period) {
1706        event->pmu->stop(event, PERF_EF_UPDATE);
1707        local64_set(&hwc->period_left, 0);
1708        event->pmu->start(event, PERF_EF_RELOAD);
1709    }
1710}
1711
1712static void perf_ctx_adjust_freq(struct perf_event_context *ctx, u64 period)
1713{
1714    struct perf_event *event;
1715    struct hw_perf_event *hwc;
1716    u64 interrupts, now;
1717    s64 delta;
1718
1719    raw_spin_lock(&ctx->lock);
1720    list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
1721        if (event->state != PERF_EVENT_STATE_ACTIVE)
1722            continue;
1723
1724        if (!event_filter_match(event))
1725            continue;
1726
1727        hwc = &event->hw;
1728
1729        interrupts = hwc->interrupts;
1730        hwc->interrupts = 0;
1731
1732        /*
1733         * unthrottle events on the tick
1734         */
1735        if (interrupts == MAX_INTERRUPTS) {
1736            perf_log_throttle(event, 1);
1737            event->pmu->start(event, 0);
1738        }
1739
1740        if (!event->attr.freq || !event->attr.sample_freq)
1741            continue;
1742
1743        event->pmu->read(event);
1744        now = local64_read(&event->count);
1745        delta = now - hwc->freq_count_stamp;
1746        hwc->freq_count_stamp = now;
1747
1748        if (delta > 0)
1749            perf_adjust_period(event, period, delta);
1750    }
1751    raw_spin_unlock(&ctx->lock);
1752}
1753
1754/*
1755 * Round-robin a context's events:
1756 */
1757static void rotate_ctx(struct perf_event_context *ctx)
1758{
1759    raw_spin_lock(&ctx->lock);
1760
1761    /*
1762     * Rotate the first entry last of non-pinned groups. Rotation might be
1763     * disabled by the inheritance code.
1764     */
1765    if (!ctx->rotate_disable)
1766        list_rotate_left(&ctx->flexible_groups);
1767
1768    raw_spin_unlock(&ctx->lock);
1769}
1770
1771/*
1772 * perf_pmu_rotate_start() and perf_rotate_context() are fully serialized
1773 * because they're strictly cpu affine and rotate_start is called with IRQs
1774 * disabled, while rotate_context is called from IRQ context.
1775 */
1776static void perf_rotate_context(struct perf_cpu_context *cpuctx)
1777{
1778    u64 interval = (u64)cpuctx->jiffies_interval * TICK_NSEC;
1779    struct perf_event_context *ctx = NULL;
1780    int rotate = 0, remove = 1;
1781
1782    if (cpuctx->ctx.nr_events) {
1783        remove = 0;
1784        if (cpuctx->ctx.nr_events != cpuctx->ctx.nr_active)
1785            rotate = 1;
1786    }
1787
1788    ctx = cpuctx->task_ctx;
1789    if (ctx && ctx->nr_events) {
1790        remove = 0;
1791        if (ctx->nr_events != ctx->nr_active)
1792            rotate = 1;
1793    }
1794
1795    perf_pmu_disable(cpuctx->ctx.pmu);
1796    perf_ctx_adjust_freq(&cpuctx->ctx, interval);
1797    if (ctx)
1798        perf_ctx_adjust_freq(ctx, interval);
1799
1800    if (!rotate)
1801        goto done;
1802
1803    cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
1804    if (ctx)
1805        task_ctx_sched_out(ctx, EVENT_FLEXIBLE);
1806
1807    rotate_ctx(&cpuctx->ctx);
1808    if (ctx)
1809        rotate_ctx(ctx);
1810
1811    cpu_ctx_sched_in(cpuctx, EVENT_FLEXIBLE);
1812    if (ctx)
1813        task_ctx_sched_in(ctx, EVENT_FLEXIBLE);
1814
1815done:
1816    if (remove)
1817        list_del_init(&cpuctx->rotation_list);
1818
1819    perf_pmu_enable(cpuctx->ctx.pmu);
1820}
1821
1822void perf_event_task_tick(void)
1823{
1824    struct list_head *head = &__get_cpu_var(rotation_list);
1825    struct perf_cpu_context *cpuctx, *tmp;
1826
1827    WARN_ON(!irqs_disabled());
1828
1829    list_for_each_entry_safe(cpuctx, tmp, head, rotation_list) {
1830        if (cpuctx->jiffies_interval == 1 ||
1831                !(jiffies % cpuctx->jiffies_interval))
1832            perf_rotate_context(cpuctx);
1833    }
1834}
1835
1836static int event_enable_on_exec(struct perf_event *event,
1837                struct perf_event_context *ctx)
1838{
1839    if (!event->attr.enable_on_exec)
1840        return 0;
1841
1842    event->attr.enable_on_exec = 0;
1843    if (event->state >= PERF_EVENT_STATE_INACTIVE)
1844        return 0;
1845
1846    __perf_event_mark_enabled(event, ctx);
1847
1848    return 1;
1849}
1850
1851/*
1852 * Enable all of a task's events that have been marked enable-on-exec.
1853 * This expects task == current.
1854 */
1855static void perf_event_enable_on_exec(struct perf_event_context *ctx)
1856{
1857    struct perf_event *event;
1858    unsigned long flags;
1859    int enabled = 0;
1860    int ret;
1861
1862    local_irq_save(flags);
1863    if (!ctx || !ctx->nr_events)
1864        goto out;
1865
1866    task_ctx_sched_out(ctx, EVENT_ALL);
1867
1868    raw_spin_lock(&ctx->lock);
1869
1870    list_for_each_entry(event, &ctx->pinned_groups, group_entry) {
1871        ret = event_enable_on_exec(event, ctx);
1872        if (ret)
1873            enabled = 1;
1874    }
1875
1876    list_for_each_entry(event, &ctx->flexible_groups, group_entry) {
1877        ret = event_enable_on_exec(event, ctx);
1878        if (ret)
1879            enabled = 1;
1880    }
1881
1882    /*
1883     * Unclone this context if we enabled any event.
1884     */
1885    if (enabled)
1886        unclone_ctx(ctx);
1887
1888    raw_spin_unlock(&ctx->lock);
1889
1890    perf_event_context_sched_in(ctx);
1891out:
1892    local_irq_restore(flags);
1893}
1894
1895/*
1896 * Cross CPU call to read the hardware event
1897 */
1898static void __perf_event_read(void *info)
1899{
1900    struct perf_event *event = info;
1901    struct perf_event_context *ctx = event->ctx;
1902    struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
1903
1904    /*
1905     * If this is a task context, we need to check whether it is
1906     * the current task context of this cpu. If not it has been
1907     * scheduled out before the smp call arrived. In that case
1908     * event->count would have been updated to a recent sample
1909     * when the event was scheduled out.
1910     */
1911    if (ctx->task && cpuctx->task_ctx != ctx)
1912        return;
1913
1914    raw_spin_lock(&ctx->lock);
1915    if (ctx->is_active)
1916        update_context_time(ctx);
1917    update_event_times(event);
1918    if (event->state == PERF_EVENT_STATE_ACTIVE)
1919        event->pmu->read(event);
1920    raw_spin_unlock(&ctx->lock);
1921}
1922
1923static inline u64 perf_event_count(struct perf_event *event)
1924{
1925    return local64_read(&event->count) + atomic64_read(&event->child_count);
1926}
1927
1928static u64 perf_event_read(struct perf_event *event)
1929{
1930    /*
1931     * If event is enabled and currently active on a CPU, update the
1932     * value in the event structure:
1933     */
1934    if (event->state == PERF_EVENT_STATE_ACTIVE) {
1935        smp_call_function_single(event->oncpu,
1936                     __perf_event_read, event, 1);
1937    } else if (event->state == PERF_EVENT_STATE_INACTIVE) {
1938        struct perf_event_context *ctx = event->ctx;
1939        unsigned long flags;
1940
1941        raw_spin_lock_irqsave(&ctx->lock, flags);
1942        /*
1943         * may read while context is not active
1944         * (e.g., thread is blocked), in that case
1945         * we cannot update context time
1946         */
1947        if (ctx->is_active)
1948            update_context_time(ctx);
1949        update_event_times(event);
1950        raw_spin_unlock_irqrestore(&ctx->lock, flags);
1951    }
1952
1953    return perf_event_count(event);
1954}
1955
1956/*
1957 * Callchain support
1958 */
1959
1960struct callchain_cpus_entries {
1961    struct rcu_head rcu_head;
1962    struct perf_callchain_entry *cpu_entries[0];
1963};
1964
1965static DEFINE_PER_CPU(int, callchain_recursion[PERF_NR_CONTEXTS]);
1966static atomic_t nr_callchain_events;
1967static DEFINE_MUTEX(callchain_mutex);
1968struct callchain_cpus_entries *callchain_cpus_entries;
1969
1970
1971__weak void perf_callchain_kernel(struct perf_callchain_entry *entry,
1972                  struct pt_regs *regs)
1973{
1974}
1975
1976__weak void perf_callchain_user(struct perf_callchain_entry *entry,
1977                struct pt_regs *regs)
1978{
1979}
1980
1981static void release_callchain_buffers_rcu(struct rcu_head *head)
1982{
1983    struct callchain_cpus_entries *entries;
1984    int cpu;
1985
1986    entries = container_of(head, struct callchain_cpus_entries, rcu_head);
1987
1988    for_each_possible_cpu(cpu)
1989        kfree(entries->cpu_entries[cpu]);
1990
1991    kfree(entries);
1992}
1993
1994static void release_callchain_buffers(void)
1995{
1996    struct callchain_cpus_entries *entries;
1997
1998    entries = callchain_cpus_entries;
1999    rcu_assign_pointer(callchain_cpus_entries, NULL);
2000    call_rcu(&entries->rcu_head, release_callchain_buffers_rcu);
2001}
2002
2003static int alloc_callchain_buffers(void)
2004{
2005    int cpu;
2006    int size;
2007    struct callchain_cpus_entries *entries;
2008
2009    /*
2010     * We can't use the percpu allocation API for data that can be
2011     * accessed from NMI. Use a temporary manual per cpu allocation
2012     * until that gets sorted out.
2013     */
2014    size = offsetof(struct callchain_cpus_entries, cpu_entries[nr_cpu_ids]);
2015
2016    entries = kzalloc(size, GFP_KERNEL);
2017    if (!entries)
2018        return -ENOMEM;
2019
2020    size = sizeof(struct perf_callchain_entry) * PERF_NR_CONTEXTS;
2021
2022    for_each_possible_cpu(cpu) {
2023        entries->cpu_entries[cpu] = kmalloc_node(size, GFP_KERNEL,
2024                             cpu_to_node(cpu));
2025        if (!entries->cpu_entries[cpu])
2026            goto fail;
2027    }
2028
2029    rcu_assign_pointer(callchain_cpus_entries, entries);
2030
2031    return 0;
2032
2033fail:
2034    for_each_possible_cpu(cpu)
2035        kfree(entries->cpu_entries[cpu]);
2036    kfree(entries);
2037
2038    return -ENOMEM;
2039}
2040
2041static int get_callchain_buffers(void)
2042{
2043    int err = 0;
2044    int count;
2045
2046    mutex_lock(&callchain_mutex);
2047
2048    count = atomic_inc_return(&nr_callchain_events);
2049    if (WARN_ON_ONCE(count < 1)) {
2050        err = -EINVAL;
2051        goto exit;
2052    }
2053
2054    if (count > 1) {
2055        /* If the allocation failed, give up */
2056        if (!callchain_cpus_entries)
2057            err = -ENOMEM;
2058        goto exit;
2059    }
2060
2061    err = alloc_callchain_buffers();
2062    if (err)
2063        release_callchain_buffers();
2064exit:
2065    mutex_unlock(&callchain_mutex);
2066
2067    return err;
2068}
2069
2070static void put_callchain_buffers(void)
2071{
2072    if (atomic_dec_and_mutex_lock(&nr_callchain_events, &callchain_mutex)) {
2073        release_callchain_buffers();
2074        mutex_unlock(&callchain_mutex);
2075    }
2076}
2077
2078static int get_recursion_context(int *recursion)
2079{
2080    int rctx;
2081
2082    if (in_nmi())
2083        rctx = 3;
2084    else if (in_irq())
2085        rctx = 2;
2086    else if (in_softirq())
2087        rctx = 1;
2088    else
2089        rctx = 0;
2090
2091    if (recursion[rctx])
2092        return -1;
2093
2094    recursion[rctx]++;
2095    barrier();
2096
2097    return rctx;
2098}
2099
2100static inline void put_recursion_context(int *recursion, int rctx)
2101{
2102    barrier();
2103    recursion[rctx]--;
2104}
2105
2106static struct perf_callchain_entry *get_callchain_entry(int *rctx)
2107{
2108    int cpu;
2109    struct callchain_cpus_entries *entries;
2110
2111    *rctx = get_recursion_context(__get_cpu_var(callchain_recursion));
2112    if (*rctx == -1)
2113        return NULL;
2114
2115    entries = rcu_dereference(callchain_cpus_entries);
2116    if (!entries)
2117        return NULL;
2118
2119    cpu = smp_processor_id();
2120
2121    return &entries->cpu_entries[cpu][*rctx];
2122}
2123
2124static void
2125put_callchain_entry(int rctx)
2126{
2127    put_recursion_context(__get_cpu_var(callchain_recursion), rctx);
2128}
2129
2130static struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
2131{
2132    int rctx;
2133    struct perf_callchain_entry *entry;
2134
2135
2136    entry = get_callchain_entry(&rctx);
2137    if (rctx == -1)
2138        return NULL;
2139
2140    if (!entry)
2141        goto exit_put;
2142
2143    entry->nr = 0;
2144
2145    if (!user_mode(regs)) {
2146        perf_callchain_store(entry, PERF_CONTEXT_KERNEL);
2147        perf_callchain_kernel(entry, regs);
2148        if (current->mm)
2149            regs = task_pt_regs(current);
2150        else
2151            regs = NULL;
2152    }
2153
2154    if (regs) {
2155        perf_callchain_store(entry, PERF_CONTEXT_USER);
2156        perf_callchain_user(entry, regs);
2157    }
2158
2159exit_put:
2160    put_callchain_entry(rctx);
2161
2162    return entry;
2163}
2164
2165/*
2166 * Initialize the perf_event context in a task_struct:
2167 */
2168static void __perf_event_init_context(struct perf_event_context *ctx)
2169{
2170    raw_spin_lock_init(&ctx->lock);
2171    mutex_init(&ctx->mutex);
2172    INIT_LIST_HEAD(&ctx->pinned_groups);
2173    INIT_LIST_HEAD(&ctx->flexible_groups);
2174    INIT_LIST_HEAD(&ctx->event_list);
2175    atomic_set(&ctx->refcount, 1);
2176}
2177
2178static struct perf_event_context *
2179alloc_perf_context(struct pmu *pmu, struct task_struct *task)
2180{
2181    struct perf_event_context *ctx;
2182
2183    ctx = kzalloc(sizeof(struct perf_event_context), GFP_KERNEL);
2184    if (!ctx)
2185        return NULL;
2186
2187    __perf_event_init_context(ctx);
2188    if (task) {
2189        ctx->task = task;
2190        get_task_struct(task);
2191    }
2192    ctx->pmu = pmu;
2193
2194    return ctx;
2195}
2196
2197static struct task_struct *
2198find_lively_task_by_vpid(pid_t vpid)
2199{
2200    struct task_struct *task;
2201    int err;
2202
2203    rcu_read_lock();
2204    if (!vpid)
2205        task = current;
2206    else
2207        task = find_task_by_vpid(vpid);
2208    if (task)
2209        get_task_struct(task);
2210    rcu_read_unlock();
2211
2212    if (!task)
2213        return ERR_PTR(-ESRCH);
2214
2215    /* Reuse ptrace permission checks for now. */
2216    err = -EACCES;
2217    if (!ptrace_may_access(task, PTRACE_MODE_READ))
2218        goto errout;
2219
2220    return task;
2221errout:
2222    put_task_struct(task);
2223    return ERR_PTR(err);
2224
2225}
2226
2227static struct perf_event_context *
2228find_get_context(struct pmu *pmu, struct task_struct *task, int cpu)
2229{
2230    struct perf_event_context *ctx;
2231    struct perf_cpu_context *cpuctx;
2232    unsigned long flags;
2233    int ctxn, err;
2234
2235    if (!task) {
2236        /* Must be root to operate on a CPU event: */
2237        if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
2238            return ERR_PTR(-EACCES);
2239
2240        /*
2241         * We could be clever and allow to attach a event to an
2242         * offline CPU and activate it when the CPU comes up, but
2243         * that's for later.
2244         */
2245        if (!cpu_online(cpu))
2246            return ERR_PTR(-ENODEV);
2247
2248        cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
2249        ctx = &cpuctx->ctx;
2250        get_ctx(ctx);
2251
2252        return ctx;
2253    }
2254
2255    err = -EINVAL;
2256    ctxn = pmu->task_ctx_nr;
2257    if (ctxn < 0)
2258        goto errout;
2259
2260retry:
2261    ctx = perf_lock_task_context(task, ctxn, &flags);
2262    if (ctx) {
2263        unclone_ctx(ctx);
2264        raw_spin_unlock_irqrestore(&ctx->lock, flags);
2265    }
2266
2267    if (!ctx) {
2268        ctx = alloc_perf_context(pmu, task);
2269        err = -ENOMEM;
2270        if (!ctx)
2271            goto errout;
2272
2273        get_ctx(ctx);
2274
2275        err = 0;
2276        mutex_lock(&task->perf_event_mutex);
2277        /*
2278         * If it has already passed perf_event_exit_task().
2279         * we must see PF_EXITING, it takes this mutex too.
2280         */
2281        if (task->flags & PF_EXITING)
2282            err = -ESRCH;
2283        else if (task->perf_event_ctxp[ctxn])
2284            err = -EAGAIN;
2285        else
2286            rcu_assign_pointer(task->perf_event_ctxp[ctxn], ctx);
2287        mutex_unlock(&task->perf_event_mutex);
2288
2289        if (unlikely(err)) {
2290            put_task_struct(task);
2291            kfree(ctx);
2292
2293            if (err == -EAGAIN)
2294                goto retry;
2295            goto errout;
2296        }
2297    }
2298
2299    return ctx;
2300
2301errout:
2302    return ERR_PTR(err);
2303}
2304
2305static void perf_event_free_filter(struct perf_event *event);
2306
2307static void free_event_rcu(struct rcu_head *head)
2308{
2309    struct perf_event *event;
2310
2311    event = container_of(head, struct perf_event, rcu_head);
2312    if (event->ns)
2313        put_pid_ns(event->ns);
2314    perf_event_free_filter(event);
2315    kfree(event);
2316}
2317
2318static void perf_buffer_put(struct perf_buffer *buffer);
2319
2320static void free_event(struct perf_event *event)
2321{
2322    irq_work_sync(&event->pending);
2323
2324    if (!event->parent) {
2325        if (event->attach_state & PERF_ATTACH_TASK)
2326            jump_label_dec(&perf_task_events);
2327        if (event->attr.mmap || event->attr.mmap_data)
2328            atomic_dec(&nr_mmap_events);
2329        if (event->attr.comm)
2330            atomic_dec(&nr_comm_events);
2331        if (event->attr.task)
2332            atomic_dec(&nr_task_events);
2333        if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)
2334            put_callchain_buffers();
2335    }
2336
2337    if (event->buffer) {
2338        perf_buffer_put(event->buffer);
2339        event->buffer = NULL;
2340    }
2341
2342    if (event->destroy)
2343        event->destroy(event);
2344
2345    if (event->ctx)
2346        put_ctx(event->ctx);
2347
2348    call_rcu(&event->rcu_head, free_event_rcu);
2349}
2350
2351int perf_event_release_kernel(struct perf_event *event)
2352{
2353    struct perf_event_context *ctx = event->ctx;
2354
2355    /*
2356     * Remove from the PMU, can't get re-enabled since we got
2357     * here because the last ref went.
2358     */
2359    perf_event_disable(event);
2360
2361    WARN_ON_ONCE(ctx->parent_ctx);
2362    /*
2363     * There are two ways this annotation is useful:
2364     *
2365     * 1) there is a lock recursion from perf_event_exit_task
2366     * see the comment there.
2367     *
2368     * 2) there is a lock-inversion with mmap_sem through
2369     * perf_event_read_group(), which takes faults while
2370     * holding ctx->mutex, however this is called after
2371     * the last filedesc died, so there is no possibility
2372     * to trigger the AB-BA case.
2373     */
2374    mutex_lock_nested(&ctx->mutex, SINGLE_DEPTH_NESTING);
2375    raw_spin_lock_irq(&ctx->lock);
2376    perf_group_detach(event);
2377    list_del_event(event, ctx);
2378    raw_spin_unlock_irq(&ctx->lock);
2379    mutex_unlock(&ctx->mutex);
2380
2381    free_event(event);
2382
2383    return 0;
2384}
2385EXPORT_SYMBOL_GPL(perf_event_release_kernel);
2386
2387/*
2388 * Called when the last reference to the file is gone.
2389 */
2390static int perf_release(struct inode *inode, struct file *file)
2391{
2392    struct perf_event *event = file->private_data;
2393    struct task_struct *owner;
2394
2395    file->private_data = NULL;
2396
2397    rcu_read_lock();
2398    owner = ACCESS_ONCE(event->owner);
2399    /*
2400     * Matches the smp_wmb() in perf_event_exit_task(). If we observe
2401     * !owner it means the list deletion is complete and we can indeed
2402     * free this event, otherwise we need to serialize on
2403     * owner->perf_event_mutex.
2404     */
2405    smp_read_barrier_depends();
2406    if (owner) {
2407        /*
2408         * Since delayed_put_task_struct() also drops the last
2409         * task reference we can safely take a new reference
2410         * while holding the rcu_read_lock().
2411         */
2412        get_task_struct(owner);
2413    }
2414    rcu_read_unlock();
2415
2416    if (owner) {
2417        mutex_lock(&owner->perf_event_mutex);
2418        /*
2419         * We have to re-check the event->owner field, if it is cleared
2420         * we raced with perf_event_exit_task(), acquiring the mutex
2421         * ensured they're done, and we can proceed with freeing the
2422         * event.
2423         */
2424        if (event->owner)
2425            list_del_init(&event->owner_entry);
2426        mutex_unlock(&owner->perf_event_mutex);
2427        put_task_struct(owner);
2428    }
2429
2430    return perf_event_release_kernel(event);
2431}
2432
2433u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running)
2434{
2435    struct perf_event *child;
2436    u64 total = 0;
2437
2438    *enabled = 0;
2439    *running = 0;
2440
2441    mutex_lock(&event->child_mutex);
2442    total += perf_event_read(event);
2443    *enabled += event->total_time_enabled +
2444            atomic64_read(&event->child_total_time_enabled);
2445    *running += event->total_time_running +
2446            atomic64_read(&event->child_total_time_running);
2447
2448    list_for_each_entry(child, &event->child_list, child_list) {
2449        total += perf_event_read(child);
2450        *enabled += child->total_time_enabled;
2451        *running += child->total_time_running;
2452    }
2453    mutex_unlock(&event->child_mutex);
2454
2455    return total;
2456}
2457EXPORT_SYMBOL_GPL(perf_event_read_value);
2458
2459static int perf_event_read_group(struct perf_event *event,
2460                   u64 read_format, char __user *buf)
2461{
2462    struct perf_event *leader = event->group_leader, *sub;
2463    int n = 0, size = 0, ret = -EFAULT;
2464    struct perf_event_context *ctx = leader->ctx;
2465    u64 values[5];
2466    u64 count, enabled, running;
2467
2468    mutex_lock(&ctx->mutex);
2469    count = perf_event_read_value(leader, &enabled, &running);
2470
2471    values[n++] = 1 + leader->nr_siblings;
2472    if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
2473        values[n++] = enabled;
2474    if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
2475        values[n++] = running;
2476    values[n++] = count;
2477    if (read_format & PERF_FORMAT_ID)
2478        values[n++] = primary_event_id(leader);
2479
2480    size = n * sizeof(u64);
2481
2482    if (copy_to_user(buf, values, size))
2483        goto unlock;
2484
2485    ret = size;
2486
2487    list_for_each_entry(sub, &leader->sibling_list, group_entry) {
2488        n = 0;
2489
2490        values[n++] = perf_event_read_value(sub, &enabled, &running);
2491        if (read_format & PERF_FORMAT_ID)
2492            values[n++] = primary_event_id(sub);
2493
2494        size = n * sizeof(u64);
2495
2496        if (copy_to_user(buf + ret, values, size)) {
2497            ret = -EFAULT;
2498            goto unlock;
2499        }
2500
2501        ret += size;
2502    }
2503unlock:
2504    mutex_unlock(&ctx->mutex);
2505
2506    return ret;
2507}
2508
2509static int perf_event_read_one(struct perf_event *event,
2510                 u64 read_format, char __user *buf)
2511{
2512    u64 enabled, running;
2513    u64 values[4];
2514    int n = 0;
2515
2516    values[n++] = perf_event_read_value(event, &enabled, &running);
2517    if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
2518        values[n++] = enabled;
2519    if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
2520        values[n++] = running;
2521    if (read_format & PERF_FORMAT_ID)
2522        values[n++] = primary_event_id(event);
2523
2524    if (copy_to_user(buf, values, n * sizeof(u64)))
2525        return -EFAULT;
2526
2527    return n * sizeof(u64);
2528}
2529
2530/*
2531 * Read the performance event - simple non blocking version for now
2532 */
2533static ssize_t
2534perf_read_hw(struct perf_event *event, char __user *buf, size_t count)
2535{
2536    u64 read_format = event->attr.read_format;
2537    int ret;
2538
2539    /*
2540     * Return end-of-file for a read on a event that is in
2541     * error state (i.e. because it was pinned but it couldn't be
2542     * scheduled on to the CPU at some point).
2543     */
2544    if (event->state == PERF_EVENT_STATE_ERROR)
2545        return 0;
2546
2547    if (count < event->read_size)
2548        return -ENOSPC;
2549
2550    WARN_ON_ONCE(event->ctx->parent_ctx);
2551    if (read_format & PERF_FORMAT_GROUP)
2552        ret = perf_event_read_group(event, read_format, buf);
2553    else
2554        ret = perf_event_read_one(event, read_format, buf);
2555
2556    return ret;
2557}
2558
2559static ssize_t
2560perf_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
2561{
2562    struct perf_event *event = file->private_data;
2563
2564    return perf_read_hw(event, buf, count);
2565}
2566
2567static unsigned int perf_poll(struct file *file, poll_table *wait)
2568{
2569    struct perf_event *event = file->private_data;
2570    struct perf_buffer *buffer;
2571    unsigned int events = POLL_HUP;
2572
2573    rcu_read_lock();
2574    buffer = rcu_dereference(event->buffer);
2575    if (buffer)
2576        events = atomic_xchg(&buffer->poll, 0);
2577    rcu_read_unlock();
2578
2579    poll_wait(file, &event->waitq, wait);
2580
2581    return events;
2582}
2583
2584static void perf_event_reset(struct perf_event *event)
2585{
2586    (void)perf_event_read(event);
2587    local64_set(&event->count, 0);
2588    perf_event_update_userpage(event);
2589}
2590
2591/*
2592 * Holding the top-level event's child_mutex means that any
2593 * descendant process that has inherited this event will block
2594 * in sync_child_event if it goes to exit, thus satisfying the
2595 * task existence requirements of perf_event_enable/disable.
2596 */
2597static void perf_event_for_each_child(struct perf_event *event,
2598                    void (*func)(struct perf_event *))
2599{
2600    struct perf_event *child;
2601
2602    WARN_ON_ONCE(event->ctx->parent_ctx);
2603    mutex_lock(&event->child_mutex);
2604    func(event);
2605    list_for_each_entry(child, &event->child_list, child_list)
2606        func(child);
2607    mutex_unlock(&event->child_mutex);
2608}
2609
2610static void perf_event_for_each(struct perf_event *event,
2611                  void (*func)(struct perf_event *))
2612{
2613    struct perf_event_context *ctx = event->ctx;
2614    struct perf_event *sibling;
2615
2616    WARN_ON_ONCE(ctx->parent_ctx);
2617    mutex_lock(&ctx->mutex);
2618    event = event->group_leader;
2619
2620    perf_event_for_each_child(event, func);
2621    func(event);
2622    list_for_each_entry(sibling, &event->sibling_list, group_entry)
2623        perf_event_for_each_child(event, func);
2624    mutex_unlock(&ctx->mutex);
2625}
2626
2627static int perf_event_period(struct perf_event *event, u64 __user *arg)
2628{
2629    struct perf_event_context *ctx = event->ctx;
2630    int ret = 0;
2631    u64 value;
2632
2633    if (!is_sampling_event(event))
2634        return -EINVAL;
2635
2636    if (copy_from_user(&value, arg, sizeof(value)))
2637        return -EFAULT;
2638
2639    if (!value)
2640        return -EINVAL;
2641
2642    raw_spin_lock_irq(&ctx->lock);
2643    if (event->attr.freq) {
2644        if (value > sysctl_perf_event_sample_rate) {
2645            ret = -EINVAL;
2646            goto unlock;
2647        }
2648
2649        event->attr.sample_freq = value;
2650    } else {
2651        event->attr.sample_period = value;
2652        event->hw.sample_period = value;
2653    }
2654unlock:
2655    raw_spin_unlock_irq(&ctx->lock);
2656
2657    return ret;
2658}
2659
2660static const struct file_operations perf_fops;
2661
2662static struct perf_event *perf_fget_light(int fd, int *fput_needed)
2663{
2664    struct file *file;
2665
2666    file = fget_light(fd, fput_needed);
2667    if (!file)
2668        return ERR_PTR(-EBADF);
2669
2670    if (file->f_op != &perf_fops) {
2671        fput_light(file, *fput_needed);
2672        *fput_needed = 0;
2673        return ERR_PTR(-EBADF);
2674    }
2675
2676    return file->private_data;
2677}
2678
2679static int perf_event_set_output(struct perf_event *event,
2680                 struct perf_event *output_event);
2681static int perf_event_set_filter(struct perf_event *event, void __user *arg);
2682
2683static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2684{
2685    struct perf_event *event = file->private_data;
2686    void (*func)(struct perf_event *);
2687    u32 flags = arg;
2688
2689    switch (cmd) {
2690    case PERF_EVENT_IOC_ENABLE:
2691        func = perf_event_enable;
2692        break;
2693    case PERF_EVENT_IOC_DISABLE:
2694        func = perf_event_disable;
2695        break;
2696    case PERF_EVENT_IOC_RESET:
2697        func = perf_event_reset;
2698        break;
2699
2700    case PERF_EVENT_IOC_REFRESH:
2701        return perf_event_refresh(event, arg);
2702
2703    case PERF_EVENT_IOC_PERIOD:
2704        return perf_event_period(event, (u64 __user *)arg);
2705
2706    case PERF_EVENT_IOC_SET_OUTPUT:
2707    {
2708        struct perf_event *output_event = NULL;
2709        int fput_needed = 0;
2710        int ret;
2711
2712        if (arg != -1) {
2713            output_event = perf_fget_light(arg, &fput_needed);
2714            if (IS_ERR(output_event))
2715                return PTR_ERR(output_event);
2716        }
2717
2718        ret = perf_event_set_output(event, output_event);
2719        if (output_event)
2720            fput_light(output_event->filp, fput_needed);
2721
2722        return ret;
2723    }
2724
2725    case PERF_EVENT_IOC_SET_FILTER:
2726        return perf_event_set_filter(event, (void __user *)arg);
2727
2728    default:
2729        return -ENOTTY;
2730    }
2731
2732    if (flags & PERF_IOC_FLAG_GROUP)
2733        perf_event_for_each(event, func);
2734    else
2735        perf_event_for_each_child(event, func);
2736
2737    return 0;
2738}
2739
2740int perf_event_task_enable(void)
2741{
2742    struct perf_event *event;
2743
2744    mutex_lock(&current->perf_event_mutex);
2745    list_for_each_entry(event, &current->perf_event_list, owner_entry)
2746        perf_event_for_each_child(event, perf_event_enable);
2747    mutex_unlock(&current->perf_event_mutex);
2748
2749    return 0;
2750}
2751
2752int perf_event_task_disable(void)
2753{
2754    struct perf_event *event;
2755
2756    mutex_lock(&current->perf_event_mutex);
2757    list_for_each_entry(event, &current->perf_event_list, owner_entry)
2758        perf_event_for_each_child(event, perf_event_disable);
2759    mutex_unlock(&current->perf_event_mutex);
2760
2761    return 0;
2762}
2763
2764#ifndef PERF_EVENT_INDEX_OFFSET
2765# define PERF_EVENT_INDEX_OFFSET 0
2766#endif
2767
2768static int perf_event_index(struct perf_event *event)
2769{
2770    if (event->hw.state & PERF_HES_STOPPED)
2771        return 0;
2772
2773    if (event->state != PERF_EVENT_STATE_ACTIVE)
2774        return 0;
2775
2776    return event->hw.idx + 1 - PERF_EVENT_INDEX_OFFSET;
2777}
2778
2779/*
2780 * Callers need to ensure there can be no nesting of this function, otherwise
2781 * the seqlock logic goes bad. We can not serialize this because the arch
2782 * code calls this from NMI context.
2783 */
2784void perf_event_update_userpage(struct perf_event *event)
2785{
2786    struct perf_event_mmap_page *userpg;
2787    struct perf_buffer *buffer;
2788
2789    rcu_read_lock();
2790    buffer = rcu_dereference(event->buffer);
2791    if (!buffer)
2792        goto unlock;
2793
2794    userpg = buffer->user_page;
2795
2796    /*
2797     * Disable preemption so as to not let the corresponding user-space
2798     * spin too long if we get preempted.
2799     */
2800    preempt_disable();
2801    ++userpg->lock;
2802    barrier();
2803    userpg->index = perf_event_index(event);
2804    userpg->offset = perf_event_count(event);
2805    if (event->state == PERF_EVENT_STATE_ACTIVE)
2806        userpg->offset -= local64_read(&event->hw.prev_count);
2807
2808    userpg->time_enabled = event->total_time_enabled +
2809            atomic64_read(&event->child_total_time_enabled);
2810
2811    userpg->time_running = event->total_time_running +
2812            atomic64_read(&event->child_total_time_running);
2813
2814    barrier();
2815    ++userpg->lock;
2816    preempt_enable();
2817unlock:
2818    rcu_read_unlock();
2819}
2820
2821static unsigned long perf_data_size(struct perf_buffer *buffer);
2822
2823static void
2824perf_buffer_init(struct perf_buffer *buffer, long watermark, int flags)
2825{
2826    long max_size = perf_data_size(buffer);
2827
2828    if (watermark)
2829        buffer->watermark = min(max_size, watermark);
2830
2831    if (!buffer->watermark)
2832        buffer->watermark = max_size / 2;
2833
2834    if (flags & PERF_BUFFER_WRITABLE)
2835        buffer->writable = 1;
2836
2837    atomic_set(&buffer->refcount, 1);
2838}
2839
2840#ifndef CONFIG_PERF_USE_VMALLOC
2841
2842/*
2843 * Back perf_mmap() with regular GFP_KERNEL-0 pages.
2844 */
2845
2846static struct page *
2847perf_mmap_to_page(struct perf_buffer *buffer, unsigned long pgoff)
2848{
2849    if (pgoff > buffer->nr_pages)
2850        return NULL;
2851
2852    if (pgoff == 0)
2853        return virt_to_page(buffer->user_page);
2854
2855    return virt_to_page(buffer->data_pages[pgoff - 1]);
2856}
2857
2858static void *perf_mmap_alloc_page(int cpu)
2859{
2860    struct page *page;
2861    int node;
2862
2863    node = (cpu == -1) ? cpu : cpu_to_node(cpu);
2864    page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
2865    if (!page)
2866        return NULL;
2867
2868    return page_address(page);
2869}
2870
2871static struct perf_buffer *
2872perf_buffer_alloc(int nr_pages, long watermark, int cpu, int flags)
2873{
2874    struct perf_buffer *buffer;
2875    unsigned long size;
2876    int i;
2877
2878    size = sizeof(struct perf_buffer);
2879    size += nr_pages * sizeof(void *);
2880
2881    buffer = kzalloc(size, GFP_KERNEL);
2882    if (!buffer)
2883        goto fail;
2884
2885    buffer->user_page = perf_mmap_alloc_page(cpu);
2886    if (!buffer->user_page)
2887        goto fail_user_page;
2888
2889    for (i = 0; i < nr_pages; i++) {
2890        buffer->data_pages[i] = perf_mmap_alloc_page(cpu);
2891        if (!buffer->data_pages[i])
2892            goto fail_data_pages;
2893    }
2894
2895    buffer->nr_pages = nr_pages;
2896
2897    perf_buffer_init(buffer, watermark, flags);
2898
2899    return buffer;
2900
2901fail_data_pages:
2902    for (i--; i >= 0; i--)
2903        free_page((unsigned long)buffer->data_pages[i]);
2904
2905    free_page((unsigned long)buffer->user_page);
2906
2907fail_user_page:
2908    kfree(buffer);
2909
2910fail:
2911    return NULL;
2912}
2913
2914static void perf_mmap_free_page(unsigned long addr)
2915{
2916    struct page *page = virt_to_page((void *)addr);
2917
2918    page->mapping = NULL;
2919    __free_page(page);
2920}
2921
2922static void perf_buffer_free(struct perf_buffer *buffer)
2923{
2924    int i;
2925
2926    perf_mmap_free_page((unsigned long)buffer->user_page);
2927    for (i = 0; i < buffer->nr_pages; i++)
2928        perf_mmap_free_page((unsigned long)buffer->data_pages[i]);
2929    kfree(buffer);
2930}
2931
2932static inline int page_order(struct perf_buffer *buffer)
2933{
2934    return 0;
2935}
2936
2937#else
2938
2939/*
2940 * Back perf_mmap() with vmalloc memory.
2941 *
2942 * Required for architectures that have d-cache aliasing issues.
2943 */
2944
2945static inline int page_order(struct perf_buffer *buffer)
2946{
2947    return buffer->page_order;
2948}
2949
2950static struct page *
2951perf_mmap_to_page(struct perf_buffer *buffer, unsigned long pgoff)
2952{
2953    if (pgoff > (1UL << page_order(buffer)))
2954        return NULL;
2955
2956    return vmalloc_to_page((void *)buffer->user_page + pgoff * PAGE_SIZE);
2957}
2958
2959static void perf_mmap_unmark_page(void *addr)
2960{
2961    struct page *page = vmalloc_to_page(addr);
2962
2963    page->mapping = NULL;
2964}
2965
2966static void perf_buffer_free_work(struct work_struct *work)
2967{
2968    struct perf_buffer *buffer;
2969    void *base;
2970    int i, nr;
2971
2972    buffer = container_of(work, struct perf_buffer, work);
2973    nr = 1 << page_order(buffer);
2974
2975    base = buffer->user_page;
2976    for (i = 0; i < nr + 1; i++)
2977        perf_mmap_unmark_page(base + (i * PAGE_SIZE));
2978
2979    vfree(base);
2980    kfree(buffer);
2981}
2982
2983static void perf_buffer_free(struct perf_buffer *buffer)
2984{
2985    schedule_work(&buffer->work);
2986}
2987
2988static struct perf_buffer *
2989perf_buffer_alloc(int nr_pages, long watermark, int cpu, int flags)
2990{
2991    struct perf_buffer *buffer;
2992    unsigned long size;
2993    void *all_buf;
2994
2995    size = sizeof(struct perf_buffer);
2996    size += sizeof(void *);
2997
2998    buffer = kzalloc(size, GFP_KERNEL);
2999    if (!buffer)
3000        goto fail;
3001
3002    INIT_WORK(&buffer->work, perf_buffer_free_work);
3003
3004    all_buf = vmalloc_user((nr_pages + 1) * PAGE_SIZE);
3005    if (!all_buf)
3006        goto fail_all_buf;
3007
3008    buffer->user_page = all_buf;
3009    buffer->data_pages[0] = all_buf + PAGE_SIZE;
3010    buffer->page_order = ilog2(nr_pages);
3011    buffer->nr_pages = 1;
3012
3013    perf_buffer_init(buffer, watermark, flags);
3014
3015    return buffer;
3016
3017fail_all_buf:
3018    kfree(buffer);
3019
3020fail:
3021    return NULL;
3022}
3023
3024#endif
3025
3026static unsigned long perf_data_size(struct perf_buffer *buffer)
3027{
3028    return buffer->nr_pages << (PAGE_SHIFT + page_order(buffer));
3029}
3030
3031static int perf_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
3032{
3033    struct perf_event *event = vma->vm_file->private_data;
3034    struct perf_buffer *buffer;
3035    int ret = VM_FAULT_SIGBUS;
3036
3037    if (vmf->flags & FAULT_FLAG_MKWRITE) {
3038        if (vmf->pgoff == 0)
3039            ret = 0;
3040        return ret;
3041    }
3042
3043    rcu_read_lock();
3044    buffer = rcu_dereference(event->buffer);
3045    if (!buffer)
3046        goto unlock;
3047
3048    if (vmf->pgoff && (vmf->flags & FAULT_FLAG_WRITE))
3049        goto unlock;
3050
3051    vmf->page = perf_mmap_to_page(buffer, vmf->pgoff);
3052    if (!vmf->page)
3053        goto unlock;
3054
3055    get_page(vmf->page);
3056    vmf->page->mapping = vma->vm_file->f_mapping;
3057    vmf->page->index = vmf->pgoff;
3058
3059    ret = 0;
3060unlock:
3061    rcu_read_unlock();
3062
3063    return ret;
3064}
3065
3066static void perf_buffer_free_rcu(struct rcu_head *rcu_head)
3067{
3068    struct perf_buffer *buffer;
3069
3070    buffer = container_of(rcu_head, struct perf_buffer, rcu_head);
3071    perf_buffer_free(buffer);
3072}
3073
3074static struct perf_buffer *perf_buffer_get(struct perf_event *event)
3075{
3076    struct perf_buffer *buffer;
3077
3078    rcu_read_lock();
3079    buffer = rcu_dereference(event->buffer);
3080    if (buffer) {
3081        if (!atomic_inc_not_zero(&buffer->refcount))
3082            buffer = NULL;
3083    }
3084    rcu_read_unlock();
3085
3086    return buffer;
3087}
3088
3089static void perf_buffer_put(struct perf_buffer *buffer)
3090{
3091    if (!atomic_dec_and_test(&buffer->refcount))
3092        return;
3093
3094    call_rcu(&buffer->rcu_head, perf_buffer_free_rcu);
3095}
3096
3097static void perf_mmap_open(struct vm_area_struct *vma)
3098{
3099    struct perf_event *event = vma->vm_file->private_data;
3100
3101    atomic_inc(&event->mmap_count);
3102}
3103
3104static void perf_mmap_close(struct vm_area_struct *vma)
3105{
3106    struct perf_event *event = vma->vm_file->private_data;
3107
3108    if (atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex)) {
3109        unsigned long size = perf_data_size(event->buffer);
3110        struct user_struct *user = event->mmap_user;
3111        struct perf_buffer *buffer = event->buffer;
3112
3113        atomic_long_sub((size >> PAGE_SHIFT) + 1, &user->locked_vm);
3114        vma->vm_mm->locked_vm -= event->mmap_locked;
3115        rcu_assign_pointer(event->buffer, NULL);
3116        mutex_unlock(&event->mmap_mutex);
3117
3118        perf_buffer_put(buffer);
3119        free_uid(user);
3120    }
3121}
3122
3123static const struct vm_operations_struct perf_mmap_vmops = {
3124    .open = perf_mmap_open,
3125    .close = perf_mmap_close,
3126    .fault = perf_mmap_fault,
3127    .page_mkwrite = perf_mmap_fault,
3128};
3129
3130static int perf_mmap(struct file *file, struct vm_area_struct *vma)
3131{
3132    struct perf_event *event = file->private_data;
3133    unsigned long user_locked, user_lock_limit;
3134    struct user_struct *user = current_user();
3135    unsigned long locked, lock_limit;
3136    struct perf_buffer *buffer;
3137    unsigned long vma_size;
3138    unsigned long nr_pages;
3139    long user_extra, extra;
3140    int ret = 0, flags = 0;
3141
3142    /*
3143     * Don't allow mmap() of inherited per-task counters. This would
3144     * create a performance issue due to all children writing to the
3145     * same buffer.
3146     */
3147    if (event->cpu == -1 && event->attr.inherit)
3148        return -EINVAL;
3149
3150    if (!(vma->vm_flags & VM_SHARED))
3151        return -EINVAL;
3152
3153    vma_size = vma->vm_end - vma->vm_start;
3154    nr_pages = (vma_size / PAGE_SIZE) - 1;
3155
3156    /*
3157     * If we have buffer pages ensure they're a power-of-two number, so we
3158     * can do bitmasks instead of modulo.
3159     */
3160    if (nr_pages != 0 && !is_power_of_2(nr_pages))
3161        return -EINVAL;
3162
3163    if (vma_size != PAGE_SIZE * (1 + nr_pages))
3164        return -EINVAL;
3165
3166    if (vma->vm_pgoff != 0)
3167        return -EINVAL;
3168
3169    WARN_ON_ONCE(event->ctx->parent_ctx);
3170    mutex_lock(&event->mmap_mutex);
3171    if (event->buffer) {
3172        if (event->buffer->nr_pages == nr_pages)
3173            atomic_inc(&event->buffer->refcount);
3174        else
3175            ret = -EINVAL;
3176        goto unlock;
3177    }
3178
3179    user_extra = nr_pages + 1;
3180    user_lock_limit = sysctl_perf_event_mlock >> (PAGE_SHIFT - 10);
3181
3182    /*
3183     * Increase the limit linearly with more CPUs:
3184     */
3185    user_lock_limit *= num_online_cpus();
3186
3187    user_locked = atomic_long_read(&user->locked_vm) + user_extra;
3188
3189    extra = 0;
3190    if (user_locked > user_lock_limit)
3191        extra = user_locked - user_lock_limit;
3192
3193    lock_limit = rlimit(RLIMIT_MEMLOCK);
3194    lock_limit >>= PAGE_SHIFT;
3195    locked = vma->vm_mm->locked_vm + extra;
3196
3197    if ((locked > lock_limit) && perf_paranoid_tracepoint_raw() &&
3198        !capable(CAP_IPC_LOCK)) {
3199        ret = -EPERM;
3200        goto unlock;
3201    }
3202
3203    WARN_ON(event->buffer);
3204
3205    if (vma->vm_flags & VM_WRITE)
3206        flags |= PERF_BUFFER_WRITABLE;
3207
3208    buffer = perf_buffer_alloc(nr_pages, event->attr.wakeup_watermark,
3209                   event->cpu, flags);
3210    if (!buffer) {
3211        ret = -ENOMEM;
3212        goto unlock;
3213    }
3214    rcu_assign_pointer(event->buffer, buffer);
3215
3216    atomic_long_add(user_extra, &user->locked_vm);
3217    event->mmap_locked = extra;
3218    event->mmap_user = get_current_user();
3219    vma->vm_mm->locked_vm += event->mmap_locked;
3220
3221unlock:
3222    if (!ret)
3223        atomic_inc(&event->mmap_count);
3224    mutex_unlock(&event->mmap_mutex);
3225
3226    vma->vm_flags |= VM_RESERVED;
3227    vma->vm_ops = &perf_mmap_vmops;
3228
3229    return ret;
3230}
3231
3232static int perf_fasync(int fd, struct file *filp, int on)
3233{
3234    struct inode *inode = filp->f_path.dentry->d_inode;
3235    struct perf_event *event = filp->private_data;
3236    int retval;
3237
3238    mutex_lock(&inode->i_mutex);
3239    retval = fasync_helper(fd, filp, on, &event->fasync);
3240    mutex_unlock(&inode->i_mutex);
3241
3242    if (retval < 0)
3243        return retval;
3244
3245    return 0;
3246}
3247
3248static const struct file_operations perf_fops = {
3249    .llseek = no_llseek,
3250    .release = perf_release,
3251    .read = perf_read,
3252    .poll = perf_poll,
3253    .unlocked_ioctl = perf_ioctl,
3254    .compat_ioctl = perf_ioctl,
3255    .mmap = perf_mmap,
3256    .fasync = perf_fasync,
3257};
3258
3259/*
3260 * Perf event wakeup
3261 *
3262 * If there's data, ensure we set the poll() state and publish everything
3263 * to user-space before waking everybody up.
3264 */
3265
3266void perf_event_wakeup(struct perf_event *event)
3267{
3268    wake_up_all(&event->waitq);
3269
3270    if (event->pending_kill) {
3271        kill_fasync(&event->fasync, SIGIO, event->pending_kill);
3272        event->pending_kill = 0;
3273    }
3274}
3275
3276static void perf_pending_event(struct irq_work *entry)
3277{
3278    struct perf_event *event = container_of(entry,
3279            struct perf_event, pending);
3280
3281    if (event->pending_disable) {
3282        event->pending_disable = 0;
3283        __perf_event_disable(event);
3284    }
3285
3286    if (event->pending_wakeup) {
3287        event->pending_wakeup = 0;
3288        perf_event_wakeup(event);
3289    }
3290}
3291
3292/*
3293 * We assume there is only KVM supporting the callbacks.
3294 * Later on, we might change it to a list if there is
3295 * another virtualization implementation supporting the callbacks.
3296 */
3297struct perf_guest_info_callbacks *perf_guest_cbs;
3298
3299int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
3300{
3301    perf_guest_cbs = cbs;
3302    return 0;
3303}
3304EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
3305
3306int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
3307{
3308    perf_guest_cbs = NULL;
3309    return 0;
3310}
3311EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
3312
3313/*
3314 * Output
3315 */
3316static bool perf_output_space(struct perf_buffer *buffer, unsigned long tail,
3317                  unsigned long offset, unsigned long head)
3318{
3319    unsigned long mask;
3320
3321    if (!buffer->writable)
3322        return true;
3323
3324    mask = perf_data_size(buffer) - 1;
3325
3326    offset = (offset - tail) & mask;
3327    head = (head - tail) & mask;
3328
3329    if ((int)(head - offset) < 0)
3330        return false;
3331
3332    return true;
3333}
3334
3335static void perf_output_wakeup(struct perf_output_handle *handle)
3336{
3337    atomic_set(&handle->buffer->poll, POLL_IN);
3338
3339    if (handle->nmi) {
3340        handle->event->pending_wakeup = 1;
3341        irq_work_queue(&handle->event->pending);
3342    } else
3343        perf_event_wakeup(handle->event);
3344}
3345
3346/*
3347 * We need to ensure a later event_id doesn't publish a head when a former
3348 * event isn't done writing. However since we need to deal with NMIs we
3349 * cannot fully serialize things.
3350 *
3351 * We only publish the head (and generate a wakeup) when the outer-most
3352 * event completes.
3353 */
3354static void perf_output_get_handle(struct perf_output_handle *handle)
3355{
3356    struct perf_buffer *buffer = handle->buffer;
3357
3358    preempt_disable();
3359    local_inc(&buffer->nest);
3360    handle->wakeup = local_read(&buffer->wakeup);
3361}
3362
3363static void perf_output_put_handle(struct perf_output_handle *handle)
3364{
3365    struct perf_buffer *buffer = handle->buffer;
3366    unsigned long head;
3367
3368again:
3369    head = local_read(&buffer->head);
3370
3371    /*
3372     * IRQ/NMI can happen here, which means we can miss a head update.
3373     */
3374
3375    if (!local_dec_and_test(&buffer->nest))
3376        goto out;
3377
3378    /*
3379     * Publish the known good head. Rely on the full barrier implied
3380     * by atomic_dec_and_test() order the buffer->head read and this
3381     * write.
3382     */
3383    buffer->user_page->data_head = head;
3384
3385    /*
3386     * Now check if we missed an update, rely on the (compiler)
3387     * barrier in atomic_dec_and_test() to re-read buffer->head.
3388     */
3389    if (unlikely(head != local_read(&buffer->head))) {
3390        local_inc(&buffer->nest);
3391        goto again;
3392    }
3393
3394    if (handle->wakeup != local_read(&buffer->wakeup))
3395        perf_output_wakeup(handle);
3396
3397out:
3398    preempt_enable();
3399}
3400
3401__always_inline void perf_output_copy(struct perf_output_handle *handle,
3402              const void *buf, unsigned int len)
3403{
3404    do {
3405        unsigned long size = min_t(unsigned long, handle->size, len);
3406
3407        memcpy(handle->addr, buf, size);
3408
3409        len -= size;
3410        handle->addr += size;
3411        buf += size;
3412        handle->size -= size;
3413        if (!handle->size) {
3414            struct perf_buffer *buffer = handle->buffer;
3415
3416            handle->page++;
3417            handle->page &= buffer->nr_pages - 1;
3418            handle->addr = buffer->data_pages[handle->page];
3419            handle->size = PAGE_SIZE << page_order(buffer);
3420        }
3421    } while (len);
3422}
3423
3424static void __perf_event_header__init_id(struct perf_event_header *header,
3425                     struct perf_sample_data *data,
3426                     struct perf_event *event)
3427{
3428    u64 sample_type = event->attr.sample_type;
3429
3430    data->type = sample_type;
3431    header->size += event->id_header_size;
3432
3433    if (sample_type & PERF_SAMPLE_TID) {
3434        /* namespace issues */
3435        data->tid_entry.pid = perf_event_pid(event, current);
3436        data->tid_entry.tid = perf_event_tid(event, current);
3437    }
3438
3439    if (sample_type & PERF_SAMPLE_TIME)
3440        data->time = perf_clock();
3441
3442    if (sample_type & PERF_SAMPLE_ID)
3443        data->id = primary_event_id(event);
3444
3445    if (sample_type & PERF_SAMPLE_STREAM_ID)
3446        data->stream_id = event->id;
3447
3448    if (sample_type & PERF_SAMPLE_CPU) {
3449        data->cpu_entry.cpu = raw_smp_processor_id();
3450        data->cpu_entry.reserved = 0;
3451    }
3452}
3453
3454static void perf_event_header__init_id(struct perf_event_header *header,
3455                       struct perf_sample_data *data,
3456                       struct perf_event *event)
3457{
3458    if (event->attr.sample_id_all)
3459        __perf_event_header__init_id(header, data, event);
3460}
3461
3462static void __perf_event__output_id_sample(struct perf_output_handle *handle,
3463                       struct perf_sample_data *data)
3464{
3465    u64 sample_type = data->type;
3466
3467    if (sample_type & PERF_SAMPLE_TID)
3468        perf_output_put(handle, data->tid_entry);
3469
3470    if (sample_type & PERF_SAMPLE_TIME)
3471        perf_output_put(handle, data->time);
3472
3473    if (sample_type & PERF_SAMPLE_ID)
3474        perf_output_put(handle, data->id);
3475
3476    if (sample_type & PERF_SAMPLE_STREAM_ID)
3477        perf_output_put(handle, data->stream_id);
3478
3479    if (sample_type & PERF_SAMPLE_CPU)
3480        perf_output_put(handle, data->cpu_entry);
3481}
3482
3483static void perf_event__output_id_sample(struct perf_event *event,
3484                     struct perf_output_handle *handle,
3485                     struct perf_sample_data *sample)
3486{
3487    if (event->attr.sample_id_all)
3488        __perf_event__output_id_sample(handle, sample);
3489}
3490
3491int perf_output_begin(struct perf_output_handle *handle,
3492              struct perf_event *event, unsigned int size,
3493              int nmi, int sample)
3494{
3495    struct perf_buffer *buffer;
3496    unsigned long tail, offset, head;
3497    int have_lost;
3498    struct perf_sample_data sample_data;
3499    struct {
3500        struct perf_event_header header;
3501        u64 id;
3502        u64 lost;
3503    } lost_event;
3504
3505    rcu_read_lock();
3506    /*
3507     * For inherited events we send all the output towards the parent.
3508     */
3509    if (event->parent)
3510        event = event->parent;
3511
3512    buffer = rcu_dereference(event->buffer);
3513    if (!buffer)
3514        goto out;
3515
3516    handle->buffer = buffer;
3517    handle->event = event;
3518    handle->nmi = nmi;
3519    handle->sample = sample;
3520
3521    if (!buffer->nr_pages)
3522        goto out;
3523
3524    have_lost = local_read(&buffer->lost);
3525    if (have_lost) {
3526        lost_event.header.size = sizeof(lost_event);
3527        perf_event_header__init_id(&lost_event.header, &sample_data,
3528                       event);
3529        size += lost_event.header.size;
3530    }
3531
3532    perf_output_get_handle(handle);
3533
3534    do {
3535        /*
3536         * Userspace could choose to issue a mb() before updating the
3537         * tail pointer. So that all reads will be completed before the
3538         * write is issued.
3539         */
3540        tail = ACCESS_ONCE(buffer->user_page->data_tail);
3541        smp_rmb();
3542        offset = head = local_read(&buffer->head);
3543        head += size;
3544        if (unlikely(!perf_output_space(buffer, tail, offset, head)))
3545            goto fail;
3546    } while (local_cmpxchg(&buffer->head, offset, head) != offset);
3547
3548    if (head - local_read(&buffer->wakeup) > buffer->watermark)
3549        local_add(buffer->watermark, &buffer->wakeup);
3550
3551    handle->page = offset >> (PAGE_SHIFT + page_order(buffer));
3552    handle->page &= buffer->nr_pages - 1;
3553    handle->size = offset & ((PAGE_SIZE << page_order(buffer)) - 1);
3554    handle->addr = buffer->data_pages[handle->page];
3555    handle->addr += handle->size;
3556    handle->size = (PAGE_SIZE << page_order(buffer)) - handle->size;
3557
3558    if (have_lost) {
3559        lost_event.header.type = PERF_RECORD_LOST;
3560        lost_event.header.misc = 0;
3561        lost_event.id = event->id;
3562        lost_event.lost = local_xchg(&buffer->lost, 0);
3563
3564        perf_output_put(handle, lost_event);
3565        perf_event__output_id_sample(event, handle, &sample_data);
3566    }
3567
3568    return 0;
3569
3570fail:
3571    local_inc(&buffer->lost);
3572    perf_output_put_handle(handle);
3573out:
3574    rcu_read_unlock();
3575
3576    return -ENOSPC;
3577}
3578
3579void perf_output_end(struct perf_output_handle *handle)
3580{
3581    struct perf_event *event = handle->event;
3582    struct perf_buffer *buffer = handle->buffer;
3583
3584    int wakeup_events = event->attr.wakeup_events;
3585
3586    if (handle->sample && wakeup_events) {
3587        int events = local_inc_return(&buffer->events);
3588        if (events >= wakeup_events) {
3589            local_sub(wakeup_events, &buffer->events);
3590            local_inc(&buffer->wakeup);
3591        }
3592    }
3593
3594    perf_output_put_handle(handle);
3595    rcu_read_unlock();
3596}
3597
3598static void perf_output_read_one(struct perf_output_handle *handle,
3599                 struct perf_event *event,
3600                 u64 enabled, u64 running)
3601{
3602    u64 read_format = event->attr.read_format;
3603    u64 values[4];
3604    int n = 0;
3605
3606    values[n++] = perf_event_count(event);
3607    if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
3608        values[n++] = enabled +
3609            atomic64_read(&event->child_total_time_enabled);
3610    }
3611    if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
3612        values[n++] = running +
3613            atomic64_read(&event->child_total_time_running);
3614    }
3615    if (read_format & PERF_FORMAT_ID)
3616        values[n++] = primary_event_id(event);
3617
3618    perf_output_copy(handle, values, n * sizeof(u64));
3619}
3620
3621/*
3622 * XXX PERF_FORMAT_GROUP vs inherited events seems difficult.
3623 */
3624static void perf_output_read_group(struct perf_output_handle *handle,
3625                struct perf_event *event,
3626                u64 enabled, u64 running)
3627{
3628    struct perf_event *leader = event->group_leader, *sub;
3629    u64 read_format = event->attr.read_format;
3630    u64 values[5];
3631    int n = 0;
3632
3633    values[n++] = 1 + leader->nr_siblings;
3634
3635    if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
3636        values[n++] = enabled;
3637
3638    if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
3639        values[n++] = running;
3640
3641    if (leader != event)
3642        leader->pmu->read(leader);
3643
3644    values[n++] = perf_event_count(leader);
3645    if (read_format & PERF_FORMAT_ID)
3646        values[n++] = primary_event_id(leader);
3647
3648    perf_output_copy(handle, values, n * sizeof(u64));
3649
3650    list_for_each_entry(sub, &leader->sibling_list, group_entry) {
3651        n = 0;
3652
3653        if (sub != event)
3654            sub->pmu->read(sub);
3655
3656        values[n++] = perf_event_count(sub);
3657        if (read_format & PERF_FORMAT_ID)
3658            values[n++] = primary_event_id(sub);
3659
3660        perf_output_copy(handle, values, n * sizeof(u64));
3661    }
3662}
3663
3664#define PERF_FORMAT_TOTAL_TIMES (PERF_FORMAT_TOTAL_TIME_ENABLED|\
3665                 PERF_FORMAT_TOTAL_TIME_RUNNING)
3666
3667static void perf_output_read(struct perf_output_handle *handle,
3668                 struct perf_event *event)
3669{
3670    u64 enabled = 0, running = 0, now, ctx_time;
3671    u64 read_format = event->attr.read_format;
3672
3673    /*
3674     * compute total_time_enabled, total_time_running
3675     * based on snapshot values taken when the event
3676     * was last scheduled in.
3677     *
3678     * we cannot simply called update_context_time()
3679     * because of locking issue as we are called in
3680     * NMI context
3681     */
3682    if (read_format & PERF_FORMAT_TOTAL_TIMES) {
3683        now = perf_clock();
3684        ctx_time = event->shadow_ctx_time + now;
3685        enabled = ctx_time - event->tstamp_enabled;
3686        running = ctx_time - event->tstamp_running;
3687    }
3688
3689    if (event->attr.read_format & PERF_FORMAT_GROUP)
3690        perf_output_read_group(handle, event, enabled, running);
3691    else
3692        perf_output_read_one(handle, event, enabled, running);
3693}
3694
3695void perf_output_sample(struct perf_output_handle *handle,
3696            struct perf_event_header *header,
3697            struct perf_sample_data *data,
3698            struct perf_event *event)
3699{
3700    u64 sample_type = data->type;
3701
3702    perf_output_put(handle, *header);
3703
3704    if (sample_type & PERF_SAMPLE_IP)
3705        perf_output_put(handle, data->ip);
3706
3707    if (sample_type & PERF_SAMPLE_TID)
3708        perf_output_put(handle, data->tid_entry);
3709
3710    if (sample_type & PERF_SAMPLE_TIME)
3711        perf_output_put(handle, data->time);
3712
3713    if (sample_type & PERF_SAMPLE_ADDR)
3714        perf_output_put(handle, data->addr);
3715
3716    if (sample_type & PERF_SAMPLE_ID)
3717        perf_output_put(handle, data->id);
3718
3719    if (sample_type & PERF_SAMPLE_STREAM_ID)
3720        perf_output_put(handle, data->stream_id);
3721
3722    if (sample_type & PERF_SAMPLE_CPU)
3723        perf_output_put(handle, data->cpu_entry);
3724
3725    if (sample_type & PERF_SAMPLE_PERIOD)
3726        perf_output_put(handle, data->period);
3727
3728    if (sample_type & PERF_SAMPLE_READ)
3729        perf_output_read(handle, event);
3730
3731    if (sample_type & PERF_SAMPLE_CALLCHAIN) {
3732        if (data->callchain) {
3733            int size = 1;
3734
3735            if (data->callchain)
3736                size += data->callchain->nr;
3737
3738            size *= sizeof(u64);
3739
3740            perf_output_copy(handle, data->callchain, size);
3741        } else {
3742            u64 nr = 0;
3743            perf_output_put(handle, nr);
3744        }
3745    }
3746
3747    if (sample_type & PERF_SAMPLE_RAW) {
3748        if (data->raw) {
3749            perf_output_put(handle, data->raw->size);
3750            perf_output_copy(handle, data->raw->data,
3751                     data->raw->size);
3752        } else {
3753            struct {
3754                u32 size;
3755                u32 data;
3756            } raw = {
3757                .size = sizeof(u32),
3758                .data = 0,
3759            };
3760            perf_output_put(handle, raw);
3761        }
3762    }
3763}
3764
3765void perf_prepare_sample(struct perf_event_header *header,
3766             struct perf_sample_data *data,
3767             struct perf_event *event,
3768             struct pt_regs *regs)
3769{
3770    u64 sample_type = event->attr.sample_type;
3771
3772    header->type = PERF_RECORD_SAMPLE;
3773    header->size = sizeof(*header) + event->header_size;
3774
3775    header->misc = 0;
3776    header->misc |= perf_misc_flags(regs);
3777
3778    __perf_event_header__init_id(header, data, event);
3779
3780    if (sample_type & PERF_SAMPLE_IP)
3781        data->ip = perf_instruction_pointer(regs);
3782
3783    if (sample_type & PERF_SAMPLE_CALLCHAIN) {
3784        int size = 1;
3785
3786        data->callchain = perf_callchain(regs);
3787
3788        if (data->callchain)
3789            size += data->callchain->nr;
3790
3791        header->size += size * sizeof(u64);
3792    }
3793
3794    if (sample_type & PERF_SAMPLE_RAW) {
3795        int size = sizeof(u32);
3796
3797        if (data->raw)
3798            size += data->raw->size;
3799        else
3800            size += sizeof(u32);
3801
3802        WARN_ON_ONCE(size & (sizeof(u64)-1));
3803        header->size += size;
3804    }
3805}
3806
3807static void perf_event_output(struct perf_event *event, int nmi,
3808                struct perf_sample_data *data,
3809                struct pt_regs *regs)
3810{
3811    struct perf_output_handle handle;
3812    struct perf_event_header header;
3813
3814    /* protect the callchain buffers */
3815    rcu_read_lock();
3816
3817    perf_prepare_sample(&header, data, event, regs);
3818
3819    if (perf_output_begin(&handle, event, header.size, nmi, 1))
3820        goto exit;
3821
3822    perf_output_sample(&handle, &header, data, event);
3823
3824    perf_output_end(&handle);
3825
3826exit:
3827    rcu_read_unlock();
3828}
3829
3830/*
3831 * read event_id
3832 */
3833
3834struct perf_read_event {
3835    struct perf_event_header header;
3836
3837    u32 pid;
3838    u32 tid;
3839};
3840
3841static void
3842perf_event_read_event(struct perf_event *event,
3843            struct task_struct *task)
3844{
3845    struct perf_output_handle handle;
3846    struct perf_sample_data sample;
3847    struct perf_read_event read_event = {
3848        .header = {
3849            .type = PERF_RECORD_READ,
3850            .misc = 0,
3851            .size = sizeof(read_event) + event->read_size,
3852        },
3853        .pid = perf_event_pid(event, task),
3854        .tid = perf_event_tid(event, task),
3855    };
3856    int ret;
3857
3858    perf_event_header__init_id(&read_event.header, &sample, event);
3859    ret = perf_output_begin(&handle, event, read_event.header.size, 0, 0);
3860    if (ret)
3861        return;
3862
3863    perf_output_put(&handle, read_event);
3864    perf_output_read(&handle, event);
3865    perf_event__output_id_sample(event, &handle, &sample);
3866
3867    perf_output_end(&handle);
3868}
3869
3870/*
3871 * task tracking -- fork/exit
3872 *
3873 * enabled by: attr.comm | attr.mmap | attr.mmap_data | attr.task
3874 */
3875
3876struct perf_task_event {
3877    struct task_struct *task;
3878    struct perf_event_context *task_ctx;
3879
3880    struct {
3881        struct perf_event_header header;
3882
3883        u32 pid;
3884        u32 ppid;
3885        u32 tid;
3886        u32 ptid;
3887        u64 time;
3888    } event_id;
3889};
3890
3891static void perf_event_task_output(struct perf_event *event,
3892                     struct perf_task_event *task_event)
3893{
3894    struct perf_output_handle handle;
3895    struct perf_sample_data sample;
3896    struct task_struct *task = task_event->task;
3897    int ret, size = task_event->event_id.header.size;
3898
3899    perf_event_header__init_id(&task_event->event_id.header, &sample, event);
3900
3901    ret = perf_output_begin(&handle, event,
3902                task_event->event_id.header.size, 0, 0);
3903    if (ret)
3904        goto out;
3905
3906    task_event->event_id.pid = perf_event_pid(event, task);
3907    task_event->event_id.ppid = perf_event_pid(event, current);
3908
3909    task_event->event_id.tid = perf_event_tid(event, task);
3910    task_event->event_id.ptid = perf_event_tid(event, current);
3911
3912    perf_output_put(&handle, task_event->event_id);
3913
3914    perf_event__output_id_sample(event, &handle, &sample);
3915
3916    perf_output_end(&handle);
3917out:
3918    task_event->event_id.header.size = size;
3919}
3920
3921static int perf_event_task_match(struct perf_event *event)
3922{
3923    if (event->state < PERF_EVENT_STATE_INACTIVE)
3924        return 0;
3925
3926    if (!event_filter_match(event))
3927        return 0;
3928
3929    if (event->attr.comm || event->attr.mmap ||
3930        event->attr.mmap_data || event->attr.task)
3931        return 1;
3932
3933    return 0;
3934}
3935
3936static void perf_event_task_ctx(struct perf_event_context *ctx,
3937                  struct perf_task_event *task_event)
3938{
3939    struct perf_event *event;
3940
3941    list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
3942        if (perf_event_task_match(event))
3943            perf_event_task_output(event, task_event);
3944    }
3945}
3946
3947static void perf_event_task_event(struct perf_task_event *task_event)
3948{
3949    struct perf_cpu_context *cpuctx;
3950    struct perf_event_context *ctx;
3951    struct pmu *pmu;
3952    int ctxn;
3953
3954    rcu_read_lock();
3955    list_for_each_entry_rcu(pmu, &pmus, entry) {
3956        cpuctx = get_cpu_ptr(pmu->pmu_cpu_context);
3957        if (cpuctx->active_pmu != pmu)
3958            goto next;
3959        perf_event_task_ctx(&cpuctx->ctx, task_event);
3960
3961        ctx = task_event->task_ctx;
3962        if (!ctx) {
3963            ctxn = pmu->task_ctx_nr;
3964            if (ctxn < 0)
3965                goto next;
3966            ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
3967        }
3968        if (ctx)
3969            perf_event_task_ctx(ctx, task_event);
3970next:
3971        put_cpu_ptr(pmu->pmu_cpu_context);
3972    }
3973    rcu_read_unlock();
3974}
3975
3976static void perf_event_task(struct task_struct *task,
3977                  struct perf_event_context *task_ctx,
3978                  int new)
3979{
3980    struct perf_task_event task_event;
3981
3982    if (!atomic_read(&nr_comm_events) &&
3983        !atomic_read(&nr_mmap_events) &&
3984        !atomic_read(&nr_task_events))
3985        return;
3986
3987    task_event = (struct perf_task_event){
3988        .task = task,
3989        .task_ctx = task_ctx,
3990        .event_id = {
3991            .header = {
3992                .type = new ? PERF_RECORD_FORK : PERF_RECORD_EXIT,
3993                .misc = 0,
3994                .size = sizeof(task_event.event_id),
3995            },
3996            /* .pid */
3997            /* .ppid */
3998            /* .tid */
3999            /* .ptid */
4000            .time = perf_clock(),
4001        },
4002    };
4003
4004    perf_event_task_event(&task_event);
4005}
4006
4007void perf_event_fork(struct task_struct *task)
4008{
4009    perf_event_task(task, NULL, 1);
4010}
4011
4012/*
4013 * comm tracking
4014 */
4015
4016struct perf_comm_event {
4017    struct task_struct *task;
4018    char *comm;
4019    int comm_size;
4020
4021    struct {
4022        struct perf_event_header header;
4023
4024        u32 pid;
4025        u32 tid;
4026    } event_id;
4027};
4028
4029static void perf_event_comm_output(struct perf_event *event,
4030                     struct perf_comm_event *comm_event)
4031{
4032    struct perf_output_handle handle;
4033    struct perf_sample_data sample;
4034    int size = comm_event->event_id.header.size;
4035    int ret;
4036
4037    perf_event_header__init_id(&comm_event->event_id.header, &sample, event);
4038    ret = perf_output_begin(&handle, event,
4039                comm_event->event_id.header.size, 0, 0);
4040
4041    if (ret)
4042        goto out;
4043
4044    comm_event->event_id.pid = perf_event_pid(event, comm_event->task);
4045    comm_event->event_id.tid = perf_event_tid(event, comm_event->task);
4046
4047    perf_output_put(&handle, comm_event->event_id);
4048    perf_output_copy(&handle, comm_event->comm,
4049                   comm_event->comm_size);
4050
4051    perf_event__output_id_sample(event, &handle, &sample);
4052
4053    perf_output_end(&handle);
4054out:
4055    comm_event->event_id.header.size = size;
4056}
4057
4058static int perf_event_comm_match(struct perf_event *event)
4059{
4060    if (event->state < PERF_EVENT_STATE_INACTIVE)
4061        return 0;
4062
4063    if (!event_filter_match(event))
4064        return 0;
4065
4066    if (event->attr.comm)
4067        return 1;
4068
4069    return 0;
4070}
4071
4072static void perf_event_comm_ctx(struct perf_event_context *ctx,
4073                  struct perf_comm_event *comm_event)
4074{
4075    struct perf_event *event;
4076
4077    list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
4078        if (perf_event_comm_match(event))
4079            perf_event_comm_output(event, comm_event);
4080    }
4081}
4082
4083static void perf_event_comm_event(struct perf_comm_event *comm_event)
4084{
4085    struct perf_cpu_context *cpuctx;
4086    struct perf_event_context *ctx;
4087    char comm[TASK_COMM_LEN];
4088    unsigned int size;
4089    struct pmu *pmu;
4090    int ctxn;
4091
4092    memset(comm, 0, sizeof(comm));
4093    strlcpy(comm, comm_event->task->comm, sizeof(comm));
4094    size = ALIGN(strlen(comm)+1, sizeof(u64));
4095
4096    comm_event->comm = comm;
4097    comm_event->comm_size = size;
4098
4099    comm_event->event_id.header.size = sizeof(comm_event->event_id) + size;
4100    rcu_read_lock();
4101    list_for_each_entry_rcu(pmu, &pmus, entry) {
4102        cpuctx = get_cpu_ptr(pmu->pmu_cpu_context);
4103        if (cpuctx->active_pmu != pmu)
4104            goto next;
4105        perf_event_comm_ctx(&cpuctx->ctx, comm_event);
4106
4107        ctxn = pmu->task_ctx_nr;
4108        if (ctxn < 0)
4109            goto next;
4110
4111        ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
4112        if (ctx)
4113            perf_event_comm_ctx(ctx, comm_event);
4114next:
4115        put_cpu_ptr(pmu->pmu_cpu_context);
4116    }
4117    rcu_read_unlock();
4118}
4119
4120void perf_event_comm(struct task_struct *task)
4121{
4122    struct perf_comm_event comm_event;
4123    struct perf_event_context *ctx;
4124    int ctxn;
4125
4126    for_each_task_context_nr(ctxn) {
4127        ctx = task->perf_event_ctxp[ctxn];
4128        if (!ctx)
4129            continue;
4130
4131        perf_event_enable_on_exec(ctx);
4132    }
4133
4134    if (!atomic_read(&nr_comm_events))
4135        return;
4136
4137    comm_event = (struct perf_comm_event){
4138        .task = task,
4139        /* .comm */
4140        /* .comm_size */
4141        .event_id = {
4142            .header = {
4143                .type = PERF_RECORD_COMM,
4144                .misc = 0,
4145                /* .size */
4146            },
4147            /* .pid */
4148            /* .tid */
4149        },
4150    };
4151
4152    perf_event_comm_event(&comm_event);
4153}
4154
4155/*
4156 * mmap tracking
4157 */
4158
4159struct perf_mmap_event {
4160    struct vm_area_struct *vma;
4161
4162    const char *file_name;
4163    int file_size;
4164
4165    struct {
4166        struct perf_event_header header;
4167
4168        u32 pid;
4169        u32 tid;
4170        u64 start;
4171        u64 len;
4172        u64 pgoff;
4173    } event_id;
4174};
4175
4176static void perf_event_mmap_output(struct perf_event *event,
4177                     struct perf_mmap_event *mmap_event)
4178{
4179    struct perf_output_handle handle;
4180    struct perf_sample_data sample;
4181    int size = mmap_event->event_id.header.size;
4182    int ret;
4183
4184    perf_event_header__init_id(&mmap_event->event_id.header, &sample, event);
4185    ret = perf_output_begin(&handle, event,
4186                mmap_event->event_id.header.size, 0, 0);
4187    if (ret)
4188        goto out;
4189
4190    mmap_event->event_id.pid = perf_event_pid(event, current);
4191    mmap_event->event_id.tid = perf_event_tid(event, current);
4192
4193    perf_output_put(&handle, mmap_event->event_id);
4194    perf_output_copy(&handle, mmap_event->file_name,
4195                   mmap_event->file_size);
4196
4197    perf_event__output_id_sample(event, &handle, &sample);
4198
4199    perf_output_end(&handle);
4200out:
4201    mmap_event->event_id.header.size = size;
4202}
4203
4204static int perf_event_mmap_match(struct perf_event *event,
4205                   struct perf_mmap_event *mmap_event,
4206                   int executable)
4207{
4208    if (event->state < PERF_EVENT_STATE_INACTIVE)
4209        return 0;
4210
4211    if (!event_filter_match(event))
4212        return 0;
4213
4214    if ((!executable && event->attr.mmap_data) ||
4215        (executable && event->attr.mmap))
4216        return 1;
4217
4218    return 0;
4219}
4220
4221static void perf_event_mmap_ctx(struct perf_event_context *ctx,
4222                  struct perf_mmap_event *mmap_event,
4223                  int executable)
4224{
4225    struct perf_event *event;
4226
4227    list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
4228        if (perf_event_mmap_match(event, mmap_event, executable))
4229            perf_event_mmap_output(event, mmap_event);
4230    }
4231}
4232
4233static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
4234{
4235    struct perf_cpu_context *cpuctx;
4236    struct perf_event_context *ctx;
4237    struct vm_area_struct *vma = mmap_event->vma;
4238    struct file *file = vma->vm_file;
4239    unsigned int size;
4240    char tmp[16];
4241    char *buf = NULL;
4242    const char *name;
4243    struct pmu *pmu;
4244    int ctxn;
4245
4246    memset(tmp, 0, sizeof(tmp));
4247
4248    if (file) {
4249        /*
4250         * d_path works from the end of the buffer backwards, so we
4251         * need to add enough zero bytes after the string to handle
4252         * the 64bit alignment we do later.
4253         */
4254        buf = kzalloc(PATH_MAX + sizeof(u64), GFP_KERNEL);
4255        if (!buf) {
4256            name = strncpy(tmp, "//enomem", sizeof(tmp));
4257            goto got_name;
4258        }
4259        name = d_path(&file->f_path, buf, PATH_MAX);
4260        if (IS_ERR(name)) {
4261            name = strncpy(tmp, "//toolong", sizeof(tmp));
4262            goto got_name;
4263        }
4264    } else {
4265        if (arch_vma_name(mmap_event->vma)) {
4266            name = strncpy(tmp, arch_vma_name(mmap_event->vma),
4267                       sizeof(tmp));
4268            goto got_name;
4269        }
4270
4271        if (!vma->vm_mm) {
4272            name = strncpy(tmp, "[vdso]", sizeof(tmp));
4273            goto got_name;
4274        } else if (vma->vm_start <= vma->vm_mm->start_brk &&
4275                vma->vm_end >= vma->vm_mm->brk) {
4276            name = strncpy(tmp, "[heap]", sizeof(tmp));
4277            goto got_name;
4278        } else if (vma->vm_start <= vma->vm_mm->start_stack &&
4279                vma->vm_end >= vma->vm_mm->start_stack) {
4280            name = strncpy(tmp, "[stack]", sizeof(tmp));
4281            goto got_name;
4282        }
4283
4284        name = strncpy(tmp, "//anon", sizeof(tmp));
4285        goto got_name;
4286    }
4287
4288got_name:
4289    size = ALIGN(strlen(name)+1, sizeof(u64));
4290
4291    mmap_event->file_name = name;
4292    mmap_event->file_size = size;
4293
4294    mmap_event->event_id.header.size = sizeof(mmap_event->event_id) + size;
4295
4296    rcu_read_lock();
4297    list_for_each_entry_rcu(pmu, &pmus, entry) {
4298        cpuctx = get_cpu_ptr(pmu->pmu_cpu_context);
4299        if (cpuctx->active_pmu != pmu)
4300            goto next;
4301        perf_event_mmap_ctx(&cpuctx->ctx, mmap_event,
4302                    vma->vm_flags & VM_EXEC);
4303
4304        ctxn = pmu->task_ctx_nr;
4305        if (ctxn < 0)
4306            goto next;
4307
4308        ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
4309        if (ctx) {
4310            perf_event_mmap_ctx(ctx, mmap_event,
4311                    vma->vm_flags & VM_EXEC);
4312        }
4313next:
4314        put_cpu_ptr(pmu->pmu_cpu_context);
4315    }
4316    rcu_read_unlock();
4317
4318    kfree(buf);
4319}
4320
4321void perf_event_mmap(struct vm_area_struct *vma)
4322{
4323    struct perf_mmap_event mmap_event;
4324
4325    if (!atomic_read(&nr_mmap_events))
4326        return;
4327
4328    mmap_event = (struct perf_mmap_event){
4329        .vma = vma,
4330        /* .file_name */
4331        /* .file_size */
4332        .event_id = {
4333            .header = {
4334                .type = PERF_RECORD_MMAP,
4335                .misc = PERF_RECORD_MISC_USER,
4336                /* .size */
4337            },
4338            /* .pid */
4339            /* .tid */
4340            .start = vma->vm_start,
4341            .len = vma->vm_end - vma->vm_start,
4342            .pgoff = (u64)vma->vm_pgoff << PAGE_SHIFT,
4343        },
4344    };
4345
4346    perf_event_mmap_event(&mmap_event);
4347}
4348
4349/*
4350 * IRQ throttle logging
4351 */
4352
4353static void perf_log_throttle(struct perf_event *event, int enable)
4354{
4355    struct perf_output_handle handle;
4356    struct perf_sample_data sample;
4357    int ret;
4358
4359    struct {
4360        struct perf_event_header header;
4361        u64 time;
4362        u64 id;
4363        u64 stream_id;
4364    } throttle_event = {
4365        .header = {
4366            .type = PERF_RECORD_THROTTLE,
4367            .misc = 0,
4368            .size = sizeof(throttle_event),
4369        },
4370        .time = perf_clock(),
4371        .id = primary_event_id(event),
4372        .stream_id = event->id,
4373    };
4374
4375    if (enable)
4376        throttle_event.header.type = PERF_RECORD_UNTHROTTLE;
4377
4378    perf_event_header__init_id(&throttle_event.header, &sample, event);
4379
4380    ret = perf_output_begin(&handle, event,
4381                throttle_event.header.size, 1, 0);
4382    if (ret)
4383        return;
4384
4385    perf_output_put(&handle, throttle_event);
4386    perf_event__output_id_sample(event, &handle, &sample);
4387    perf_output_end(&handle);
4388}
4389
4390/*
4391 * Generic event overflow handling, sampling.
4392 */
4393
4394static int __perf_event_overflow(struct perf_event *event, int nmi,
4395                   int throttle, struct perf_sample_data *data,
4396                   struct pt_regs *regs)
4397{
4398    int events = atomic_read(&event->event_limit);
4399    struct hw_perf_event *hwc = &event->hw;
4400    int ret = 0;
4401
4402    /*
4403     * Non-sampling counters might still use the PMI to fold short
4404     * hardware counters, ignore those.
4405     */
4406    if (unlikely(!is_sampling_event(event)))
4407        return 0;
4408
4409    if (!throttle) {
4410        hwc->interrupts++;
4411    } else {
4412        if (hwc->interrupts != MAX_INTERRUPTS) {
4413            hwc->interrupts++;
4414            if (HZ * hwc->interrupts >
4415                    (u64)sysctl_perf_event_sample_rate) {
4416                hwc->interrupts = MAX_INTERRUPTS;
4417                perf_log_throttle(event, 0);
4418                ret = 1;
4419            }
4420        } else {
4421            /*
4422             * Keep re-disabling events even though on the previous
4423             * pass we disabled it - just in case we raced with a
4424             * sched-in and the event got enabled again:
4425             */
4426            ret = 1;
4427        }
4428    }
4429
4430    if (event->attr.freq) {
4431        u64 now = perf_clock();
4432        s64 delta = now - hwc->freq_time_stamp;
4433
4434        hwc->freq_time_stamp = now;
4435
4436        if (delta > 0 && delta < 2*TICK_NSEC)
4437            perf_adjust_period(event, delta, hwc->last_period);
4438    }
4439
4440    /*
4441     * XXX event_limit might not quite work as expected on inherited
4442     * events
4443     */
4444
4445    event->pending_kill = POLL_IN;
4446    if (events && atomic_dec_and_test(&event->event_limit)) {
4447        ret = 1;
4448        event->pending_kill = POLL_HUP;
4449        if (nmi) {
4450            event->pending_disable = 1;
4451            irq_work_queue(&event->pending);
4452        } else
4453            perf_event_disable(event);
4454    }
4455
4456    if (event->overflow_handler)
4457        event->overflow_handler(event, nmi, data, regs);
4458    else
4459        perf_event_output(event, nmi, data, regs);
4460
4461    return ret;
4462}
4463
4464int perf_event_overflow(struct perf_event *event, int nmi,
4465              struct perf_sample_data *data,
4466              struct pt_regs *regs)
4467{
4468    return __perf_event_overflow(event, nmi, 1, data, regs);
4469}
4470
4471/*
4472 * Generic software event infrastructure
4473 */
4474
4475struct swevent_htable {
4476    struct swevent_hlist *swevent_hlist;
4477    struct mutex hlist_mutex;
4478    int hlist_refcount;
4479
4480    /* Recursion avoidance in each contexts */
4481    int recursion[PERF_NR_CONTEXTS];
4482};
4483
4484static DEFINE_PER_CPU(struct swevent_htable, swevent_htable);
4485
4486/*
4487 * We directly increment event->count and keep a second value in
4488 * event->hw.period_left to count intervals. This period event
4489 * is kept in the range [-sample_period, 0] so that we can use the
4490 * sign as trigger.
4491 */
4492
4493static u64 perf_swevent_set_period(struct perf_event *event)
4494{
4495    struct hw_perf_event *hwc = &event->hw;
4496    u64 period = hwc->last_period;
4497    u64 nr, offset;
4498    s64 old, val;
4499
4500    hwc->last_period = hwc->sample_period;
4501
4502again:
4503    old = val = local64_read(&hwc->period_left);
4504    if (val < 0)
4505        return 0;
4506
4507    nr = div64_u64(period + val, period);
4508    offset = nr * period;
4509    val -= offset;
4510    if (local64_cmpxchg(&hwc->period_left, old, val) != old)
4511        goto again;
4512
4513    return nr;
4514}
4515
4516static void perf_swevent_overflow(struct perf_event *event, u64 overflow,
4517                    int nmi, struct perf_sample_data *data,
4518                    struct pt_regs *regs)
4519{
4520    struct hw_perf_event *hwc = &event->hw;
4521    int throttle = 0;
4522
4523    data->period = event->hw.last_period;
4524    if (!overflow)
4525        overflow = perf_swevent_set_period(event);
4526
4527    if (hwc->interrupts == MAX_INTERRUPTS)
4528        return;
4529
4530    for (; overflow; overflow--) {
4531        if (__perf_event_overflow(event, nmi, throttle,
4532                        data, regs)) {
4533            /*
4534             * We inhibit the overflow from happening when
4535             * hwc->interrupts == MAX_INTERRUPTS.
4536             */
4537            break;
4538        }
4539        throttle = 1;
4540    }
4541}
4542
4543static void perf_swevent_event(struct perf_event *event, u64 nr,
4544                   int nmi, struct perf_sample_data *data,
4545                   struct pt_regs *regs)
4546{
4547    struct hw_perf_event *hwc = &event->hw;
4548
4549    local64_add(nr, &event->count);
4550
4551    if (!regs)
4552        return;
4553
4554    if (!is_sampling_event(event))
4555        return;
4556
4557    if (nr == 1 && hwc->sample_period == 1 && !event->attr.freq)
4558        return perf_swevent_overflow(event, 1, nmi, data, regs);
4559
4560    if (local64_add_negative(nr, &hwc->period_left))
4561        return;
4562
4563    perf_swevent_overflow(event, 0, nmi, data, regs);
4564}
4565
4566static int perf_exclude_event(struct perf_event *event,
4567                  struct pt_regs *regs)
4568{
4569    if (event->hw.state & PERF_HES_STOPPED)
4570        return 0;
4571
4572    if (regs) {
4573        if (event->attr.exclude_user && user_mode(regs))
4574            return 1;
4575
4576        if (event->attr.exclude_kernel && !user_mode(regs))
4577            return 1;
4578    }
4579
4580    return 0;
4581}
4582
4583static int perf_swevent_match(struct perf_event *event,
4584                enum perf_type_id type,
4585                u32 event_id,
4586                struct perf_sample_data *data,
4587                struct pt_regs *regs)
4588{
4589    if (event->attr.type != type)
4590        return 0;
4591
4592    if (event->attr.config != event_id)
4593        return 0;
4594
4595    if (perf_exclude_event(event, regs))
4596        return 0;
4597
4598    return 1;
4599}
4600
4601static inline u64 swevent_hash(u64 type, u32 event_id)
4602{
4603    u64 val = event_id | (type << 32);
4604
4605    return hash_64(val, SWEVENT_HLIST_BITS);
4606}
4607
4608static inline struct hlist_head *
4609__find_swevent_head(struct swevent_hlist *hlist, u64 type, u32 event_id)
4610{
4611    u64 hash = swevent_hash(type, event_id);
4612
4613    return &hlist->heads[hash];
4614}
4615
4616/* For the read side: events when they trigger */
4617static inline struct hlist_head *
4618find_swevent_head_rcu(struct swevent_htable *swhash, u64 type, u32 event_id)
4619{
4620    struct swevent_hlist *hlist;
4621
4622    hlist = rcu_dereference(swhash->swevent_hlist);
4623    if (!hlist)
4624        return NULL;
4625
4626    return __find_swevent_head(hlist, type, event_id);
4627}
4628
4629/* For the event head insertion and removal in the hlist */
4630static inline struct hlist_head *
4631find_swevent_head(struct swevent_htable *swhash, struct perf_event *event)
4632{
4633    struct swevent_hlist *hlist;
4634    u32 event_id = event->attr.config;
4635    u64 type = event->attr.type;
4636
4637    /*
4638     * Event scheduling is always serialized against hlist allocation
4639     * and release. Which makes the protected version suitable here.
4640     * The context lock guarantees that.
4641     */
4642    hlist = rcu_dereference_protected(swhash->swevent_hlist,
4643                      lockdep_is_held(&event->ctx->lock));
4644    if (!hlist)
4645        return NULL;
4646
4647    return __find_swevent_head(hlist, type, event_id);
4648}
4649
4650static void do_perf_sw_event(enum perf_type_id type, u32 event_id,
4651                    u64 nr, int nmi,
4652                    struct perf_sample_data *data,
4653                    struct pt_regs *regs)
4654{
4655    struct swevent_htable *swhash = &__get_cpu_var(swevent_htable);
4656    struct perf_event *event;
4657    struct hlist_node *node;
4658    struct hlist_head *head;
4659
4660    rcu_read_lock();
4661    head = find_swevent_head_rcu(swhash, type, event_id);
4662    if (!head)
4663        goto end;
4664
4665    hlist_for_each_entry_rcu(event, node, head, hlist_entry) {
4666        if (perf_swevent_match(event, type, event_id, data, regs))
4667            perf_swevent_event(event, nr, nmi, data, regs);
4668    }
4669end:
4670    rcu_read_unlock();
4671}
4672
4673int perf_swevent_get_recursion_context(void)
4674{
4675    struct swevent_htable *swhash = &__get_cpu_var(swevent_htable);
4676
4677    return get_recursion_context(swhash->recursion);
4678}
4679EXPORT_SYMBOL_GPL(perf_swevent_get_recursion_context);
4680
4681inline void perf_swevent_put_recursion_context(int rctx)
4682{
4683    struct swevent_htable *swhash = &__get_cpu_var(swevent_htable);
4684
4685    put_recursion_context(swhash->recursion, rctx);
4686}
4687
4688void __perf_sw_event(u32 event_id, u64 nr, int nmi,
4689                struct pt_regs *regs, u64 addr)
4690{
4691    struct perf_sample_data data;
4692    int rctx;
4693
4694    preempt_disable_notrace();
4695    rctx = perf_swevent_get_recursion_context();
4696    if (rctx < 0)
4697        return;
4698
4699    perf_sample_data_init(&data, addr);
4700
4701    do_perf_sw_event(PERF_TYPE_SOFTWARE, event_id, nr, nmi, &data, regs);
4702
4703    perf_swevent_put_recursion_context(rctx);
4704    preempt_enable_notrace();
4705}
4706
4707static void perf_swevent_read(struct perf_event *event)
4708{
4709}
4710
4711static int perf_swevent_add(struct perf_event *event, int flags)
4712{
4713    struct swevent_htable *swhash = &__get_cpu_var(swevent_htable);
4714    struct hw_perf_event *hwc = &event->hw;
4715    struct hlist_head *head;
4716
4717    if (is_sampling_event(event)) {
4718        hwc->last_period = hwc->sample_period;
4719        perf_swevent_set_period(event);
4720    }
4721
4722    hwc->state = !(flags & PERF_EF_START);
4723
4724    head = find_swevent_head(swhash, event);
4725    if (WARN_ON_ONCE(!head))
4726        return -EINVAL;
4727
4728    hlist_add_head_rcu(&event->hlist_entry, head);
4729
4730    return 0;
4731}
4732
4733static void perf_swevent_del(struct perf_event *event, int flags)
4734{
4735    hlist_del_rcu(&event->hlist_entry);
4736}
4737
4738static void perf_swevent_start(struct perf_event *event, int flags)
4739{
4740    event->hw.state = 0;
4741}
4742
4743static void perf_swevent_stop(struct perf_event *event, int flags)
4744{
4745    event->hw.state = PERF_HES_STOPPED;
4746}
4747
4748/* Deref the hlist from the update side */
4749static inline struct swevent_hlist *
4750swevent_hlist_deref(struct swevent_htable *swhash)
4751{
4752    return rcu_dereference_protected(swhash->swevent_hlist,
4753                     lockdep_is_held(&swhash->hlist_mutex));
4754}
4755
4756static void swevent_hlist_release_rcu(struct rcu_head *rcu_head)
4757{
4758    struct swevent_hlist *hlist;
4759
4760    hlist = container_of(rcu_head, struct swevent_hlist, rcu_head);
4761    kfree(hlist);
4762}
4763
4764static void swevent_hlist_release(struct swevent_htable *swhash)
4765{
4766    struct swevent_hlist *hlist = swevent_hlist_deref(swhash);
4767
4768    if (!hlist)
4769        return;
4770
4771    rcu_assign_pointer(swhash->swevent_hlist, NULL);
4772    call_rcu(&hlist->rcu_head, swevent_hlist_release_rcu);
4773}
4774
4775static void swevent_hlist_put_cpu(struct perf_event *event, int cpu)
4776{
4777    struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
4778
4779    mutex_lock(&swhash->hlist_mutex);
4780
4781    if (!--swhash->hlist_refcount)
4782        swevent_hlist_release(swhash);
4783
4784    mutex_unlock(&swhash->hlist_mutex);
4785}
4786
4787static void swevent_hlist_put(struct perf_event *event)
4788{
4789    int cpu;
4790
4791    if (event->cpu != -1) {
4792        swevent_hlist_put_cpu(event, event->cpu);
4793        return;
4794    }
4795
4796    for_each_possible_cpu(cpu)
4797        swevent_hlist_put_cpu(event, cpu);
4798}
4799
4800static int swevent_hlist_get_cpu(struct perf_event *event, int cpu)
4801{
4802    struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
4803    int err = 0;
4804
4805    mutex_lock(&swhash->hlist_mutex);
4806
4807    if (!swevent_hlist_deref(swhash) && cpu_online(cpu)) {
4808        struct swevent_hlist *hlist;
4809
4810        hlist = kzalloc(sizeof(*hlist), GFP_KERNEL);
4811        if (!hlist) {
4812            err = -ENOMEM;
4813            goto exit;
4814        }
4815        rcu_assign_pointer(swhash->swevent_hlist, hlist);
4816    }
4817    swhash->hlist_refcount++;
4818exit:
4819    mutex_unlock(&swhash->hlist_mutex);
4820
4821    return err;
4822}
4823
4824static int swevent_hlist_get(struct perf_event *event)
4825{
4826    int err;
4827    int cpu, failed_cpu;
4828
4829    if (event->cpu != -1)
4830        return swevent_hlist_get_cpu(event, event->cpu);
4831
4832    get_online_cpus();
4833    for_each_possible_cpu(cpu) {
4834        err = swevent_hlist_get_cpu(event, cpu);
4835        if (err) {
4836            failed_cpu = cpu;
4837            goto fail;
4838        }
4839    }
4840    put_online_cpus();
4841
4842    return 0;
4843fail:
4844    for_each_possible_cpu(cpu) {
4845        if (cpu == failed_cpu)
4846            break;
4847        swevent_hlist_put_cpu(event, cpu);
4848    }
4849
4850    put_online_cpus();
4851    return err;
4852}
4853
4854atomic_t perf_swevent_enabled[PERF_COUNT_SW_MAX];
4855
4856static void sw_perf_event_destroy(struct perf_event *event)
4857{
4858    u64 event_id = event->attr.config;
4859
4860    WARN_ON(event->parent);
4861
4862    jump_label_dec(&perf_swevent_enabled[event_id]);
4863    swevent_hlist_put(event);
4864}
4865
4866static int perf_swevent_init(struct perf_event *event)
4867{
4868    int event_id = event->attr.config;
4869
4870    if (event->attr.type != PERF_TYPE_SOFTWARE)
4871        return -ENOENT;
4872
4873    switch (event_id) {
4874    case PERF_COUNT_SW_CPU_CLOCK:
4875    case PERF_COUNT_SW_TASK_CLOCK:
4876        return -ENOENT;
4877
4878    default:
4879        break;
4880    }
4881
4882    if (event_id >= PERF_COUNT_SW_MAX)
4883        return -ENOENT;
4884
4885    if (!event->parent) {
4886        int err;
4887
4888        err = swevent_hlist_get(event);
4889        if (err)
4890            return err;
4891
4892        jump_label_inc(&perf_swevent_enabled[event_id]);
4893        event->destroy = sw_perf_event_destroy;
4894    }
4895
4896    return 0;
4897}
4898
4899static struct pmu perf_swevent = {
4900    .task_ctx_nr = perf_sw_context,
4901
4902    .event_init = perf_swevent_init,
4903    .add = perf_swevent_add,
4904    .del = perf_swevent_del,
4905    .start = perf_swevent_start,
4906    .stop = perf_swevent_stop,
4907    .read = perf_swevent_read,
4908};
4909
4910#ifdef CONFIG_EVENT_TRACING
4911
4912static int perf_tp_filter_match(struct perf_event *event,
4913                struct perf_sample_data *data)
4914{
4915    void *record = data->raw->data;
4916
4917    if (likely(!event->filter) || filter_match_preds(event->filter, record))
4918        return 1;
4919    return 0;
4920}
4921
4922static int perf_tp_event_match(struct perf_event *event,
4923                struct perf_sample_data *data,
4924                struct pt_regs *regs)
4925{
4926    /*
4927     * All tracepoints are from kernel-space.
4928     */
4929    if (event->attr.exclude_kernel)
4930        return 0;
4931
4932    if (!perf_tp_filter_match(event, data))
4933        return 0;
4934
4935    return 1;
4936}
4937
4938void perf_tp_event(u64 addr, u64 count, void *record, int entry_size,
4939           struct pt_regs *regs, struct hlist_head *head, int rctx)
4940{
4941    struct perf_sample_data data;
4942    struct perf_event *event;
4943    struct hlist_node *node;
4944
4945    struct perf_raw_record raw = {
4946        .size = entry_size,
4947        .data = record,
4948    };
4949
4950    perf_sample_data_init(&data, addr);
4951    data.raw = &raw;
4952
4953    hlist_for_each_entry_rcu(event, node, head, hlist_entry) {
4954        if (perf_tp_event_match(event, &data, regs))
4955            perf_swevent_event(event, count, 1, &data, regs);
4956    }
4957
4958    perf_swevent_put_recursion_context(rctx);
4959}
4960EXPORT_SYMBOL_GPL(perf_tp_event);
4961
4962static void tp_perf_event_destroy(struct perf_event *event)
4963{
4964    perf_trace_destroy(event);
4965}
4966
4967static int perf_tp_event_init(struct perf_event *event)
4968{
4969    int err;
4970
4971    if (event->attr.type != PERF_TYPE_TRACEPOINT)
4972        return -ENOENT;
4973
4974    err = perf_trace_init(event);
4975    if (err)
4976        return err;
4977
4978    event->destroy = tp_perf_event_destroy;
4979
4980    return 0;
4981}
4982
4983static struct pmu perf_tracepoint = {
4984    .task_ctx_nr = perf_sw_context,
4985
4986    .event_init = perf_tp_event_init,
4987    .add = perf_trace_add,
4988    .del = perf_trace_del,
4989    .start = perf_swevent_start,
4990    .stop = perf_swevent_stop,
4991    .read = perf_swevent_read,
4992};
4993
4994static inline void perf_tp_register(void)
4995{
4996    perf_pmu_register(&perf_tracepoint, "tracepoint", PERF_TYPE_TRACEPOINT);
4997}
4998
4999static int perf_event_set_filter(struct perf_event *event, void __user *arg)
5000{
5001    char *filter_str;
5002    int ret;
5003
5004    if (event->attr.type != PERF_TYPE_TRACEPOINT)
5005        return -EINVAL;
5006
5007    filter_str = strndup_user(arg, PAGE_SIZE);
5008    if (IS_ERR(filter_str))
5009        return PTR_ERR(filter_str);
5010
5011    ret = ftrace_profile_set_filter(event, event->attr.config, filter_str);
5012
5013    kfree(filter_str);
5014    return ret;
5015}
5016
5017static void perf_event_free_filter(struct perf_event *event)
5018{
5019    ftrace_profile_free_filter(event);
5020}
5021
5022#else
5023
5024static inline void perf_tp_register(void)
5025{
5026}
5027
5028static int perf_event_set_filter(struct perf_event *event, void __user *arg)
5029{
5030    return -ENOENT;
5031}
5032
5033static void perf_event_free_filter(struct perf_event *event)
5034{
5035}
5036
5037#endif /* CONFIG_EVENT_TRACING */
5038
5039#ifdef CONFIG_HAVE_HW_BREAKPOINT
5040void perf_bp_event(struct perf_event *bp, void *data)
5041{
5042    struct perf_sample_data sample;
5043    struct pt_regs *regs = data;
5044
5045    perf_sample_data_init(&sample, bp->attr.bp_addr);
5046
5047    if (!bp->hw.state && !perf_exclude_event(bp, regs))
5048        perf_swevent_event(bp, 1, 1, &sample, regs);
5049}
5050#endif
5051
5052/*
5053 * hrtimer based swevent callback
5054 */
5055
5056static enum hrtimer_restart perf_swevent_hrtimer(struct hrtimer *hrtimer)
5057{
5058    enum hrtimer_restart ret = HRTIMER_RESTART;
5059    struct perf_sample_data data;
5060    struct pt_regs *regs;
5061    struct perf_event *event;
5062    u64 period;
5063
5064    event = container_of(hrtimer, struct perf_event, hw.hrtimer);
5065    event->pmu->read(event);
5066
5067    perf_sample_data_init(&data, 0);
5068    data.period = event->hw.last_period;
5069    regs = get_irq_regs();
5070
5071    if (regs && !perf_exclude_event(event, regs)) {
5072        if (!(event->attr.exclude_idle && current->pid == 0))
5073            if (perf_event_overflow(event, 0, &data, regs))
5074                ret = HRTIMER_NORESTART;
5075    }
5076
5077    period = max_t(u64, 10000, event->hw.sample_period);
5078    hrtimer_forward_now(hrtimer, ns_to_ktime(period));
5079
5080    return ret;
5081}
5082
5083static void perf_swevent_start_hrtimer(struct perf_event *event)
5084{
5085    struct hw_perf_event *hwc = &event->hw;
5086    s64 period;
5087
5088    if (!is_sampling_event(event))
5089        return;
5090
5091    hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
5092    hwc->hrtimer.function = perf_swevent_hrtimer;
5093
5094    period = local64_read(&hwc->period_left);
5095    if (period) {
5096        if (period < 0)
5097            period = 10000;
5098
5099        local64_set(&hwc->period_left, 0);
5100    } else {
5101        period = max_t(u64, 10000, hwc->sample_period);
5102    }
5103    __hrtimer_start_range_ns(&hwc->hrtimer,
5104                ns_to_ktime(period), 0,
5105                HRTIMER_MODE_REL_PINNED, 0);
5106}
5107
5108static void perf_swevent_cancel_hrtimer(struct perf_event *event)
5109{
5110    struct hw_perf_event *hwc = &event->hw;
5111
5112    if (is_sampling_event(event)) {
5113        ktime_t remaining = hrtimer_get_remaining(&hwc->hrtimer);
5114        local64_set(&hwc->period_left, ktime_to_ns(remaining));
5115
5116        hrtimer_cancel(&hwc->hrtimer);
5117    }
5118}
5119
5120/*
5121 * Software event: cpu wall time clock
5122 */
5123
5124static void cpu_clock_event_update(struct perf_event *event)
5125{
5126    s64 prev;
5127    u64 now;
5128
5129    now = local_clock();
5130    prev = local64_xchg(&event->hw.prev_count, now);
5131    local64_add(now - prev, &event->count);
5132}
5133
5134static void cpu_clock_event_start(struct perf_event *event, int flags)
5135{
5136    local64_set(&event->hw.prev_count, local_clock());
5137    perf_swevent_start_hrtimer(event);
5138}
5139
5140static void cpu_clock_event_stop(struct perf_event *event, int flags)
5141{
5142    perf_swevent_cancel_hrtimer(event);
5143    cpu_clock_event_update(event);
5144}
5145
5146static int cpu_clock_event_add(struct perf_event *event, int flags)
5147{
5148    if (flags & PERF_EF_START)
5149        cpu_clock_event_start(event, flags);
5150
5151    return 0;
5152}
5153
5154static void cpu_clock_event_del(struct perf_event *event, int flags)
5155{
5156    cpu_clock_event_stop(event, flags);
5157}
5158
5159static void cpu_clock_event_read(struct perf_event *event)
5160{
5161    cpu_clock_event_update(event);
5162}
5163
5164static int cpu_clock_event_init(struct perf_event *event)
5165{
5166    if (event->attr.type != PERF_TYPE_SOFTWARE)
5167        return -ENOENT;
5168
5169    if (event->attr.config != PERF_COUNT_SW_CPU_CLOCK)
5170        return -ENOENT;
5171
5172    return 0;
5173}
5174
5175static struct pmu perf_cpu_clock = {
5176    .task_ctx_nr = perf_sw_context,
5177
5178    .event_init = cpu_clock_event_init,
5179    .add = cpu_clock_event_add,
5180    .del = cpu_clock_event_del,
5181    .start = cpu_clock_event_start,
5182    .stop = cpu_clock_event_stop,
5183    .read = cpu_clock_event_read,
5184};
5185
5186/*
5187 * Software event: task time clock
5188 */
5189
5190static void task_clock_event_update(struct perf_event *event, u64 now)
5191{
5192    u64 prev;
5193    s64 delta;
5194
5195    prev = local64_xchg(&event->hw.prev_count, now);
5196    delta = now - prev;
5197    local64_add(delta, &event->count);
5198}
5199
5200static void task_clock_event_start(struct perf_event *event, int flags)
5201{
5202    local64_set(&event->hw.prev_count, event->ctx->time);
5203    perf_swevent_start_hrtimer(event);
5204}
5205
5206static void task_clock_event_stop(struct perf_event *event, int flags)
5207{
5208    perf_swevent_cancel_hrtimer(event);
5209    task_clock_event_update(event, event->ctx->time);
5210}
5211
5212static int task_clock_event_add(struct perf_event *event, int flags)
5213{
5214    if (flags & PERF_EF_START)
5215        task_clock_event_start(event, flags);
5216
5217    return 0;
5218}
5219
5220static void task_clock_event_del(struct perf_event *event, int flags)
5221{
5222    task_clock_event_stop(event, PERF_EF_UPDATE);
5223}
5224
5225static void task_clock_event_read(struct perf_event *event)
5226{
5227    u64 time;
5228
5229    if (!in_nmi()) {
5230        update_context_time(event->ctx);
5231        time = event->ctx->time;
5232    } else {
5233        u64 now = perf_clock();
5234        u64 delta = now - event->ctx->timestamp;
5235        time = event->ctx->time + delta;
5236    }
5237
5238    task_clock_event_update(event, time);
5239}
5240
5241static int task_clock_event_init(struct perf_event *event)
5242{
5243    if (event->attr.type != PERF_TYPE_SOFTWARE)
5244        return -ENOENT;
5245
5246    if (event->attr.config != PERF_COUNT_SW_TASK_CLOCK)
5247        return -ENOENT;
5248
5249    return 0;
5250}
5251
5252static struct pmu perf_task_clock = {
5253    .task_ctx_nr = perf_sw_context,
5254
5255    .event_init = task_clock_event_init,
5256    .add = task_clock_event_add,
5257    .del = task_clock_event_del,
5258    .start = task_clock_event_start,
5259    .stop = task_clock_event_stop,
5260    .read = task_clock_event_read,
5261};
5262
5263static void perf_pmu_nop_void(struct pmu *pmu)
5264{
5265}
5266
5267static int perf_pmu_nop_int(struct pmu *pmu)
5268{
5269    return 0;
5270}
5271
5272static void perf_pmu_start_txn(struct pmu *pmu)
5273{
5274    perf_pmu_disable(pmu);
5275}
5276
5277static int perf_pmu_commit_txn(struct pmu *pmu)
5278{
5279    perf_pmu_enable(pmu);
5280    return 0;
5281}
5282
5283static void perf_pmu_cancel_txn(struct pmu *pmu)
5284{
5285    perf_pmu_enable(pmu);
5286}
5287
5288/*
5289 * Ensures all contexts with the same task_ctx_nr have the same
5290 * pmu_cpu_context too.
5291 */
5292static void *find_pmu_context(int ctxn)
5293{
5294    struct pmu *pmu;
5295
5296    if (ctxn < 0)
5297        return NULL;
5298
5299    list_for_each_entry(pmu, &pmus, entry) {
5300        if (pmu->task_ctx_nr == ctxn)
5301            return pmu->pmu_cpu_context;
5302    }
5303
5304    return NULL;
5305}
5306
5307static void update_pmu_context(struct pmu *pmu, struct pmu *old_pmu)
5308{
5309    int cpu;
5310
5311    for_each_possible_cpu(cpu) {
5312        struct perf_cpu_context *cpuctx;
5313
5314        cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
5315
5316        if (cpuctx->active_pmu == old_pmu)
5317            cpuctx->active_pmu = pmu;
5318    }
5319}
5320
5321static void free_pmu_context(struct pmu *pmu)
5322{
5323    struct pmu *i;
5324
5325    mutex_lock(&pmus_lock);
5326    /*
5327     * Like a real lame refcount.
5328     */
5329    list_for_each_entry(i, &pmus, entry) {
5330        if (i->pmu_cpu_context == pmu->pmu_cpu_context) {
5331            update_pmu_context(i, pmu);
5332            goto out;
5333        }
5334    }
5335
5336    free_percpu(pmu->pmu_cpu_context);
5337out:
5338    mutex_unlock(&pmus_lock);
5339}
5340static struct idr pmu_idr;
5341
5342static ssize_t
5343type_show(struct device *dev, struct device_attribute *attr, char *page)
5344{
5345    struct pmu *pmu = dev_get_drvdata(dev);
5346
5347    return snprintf(page, PAGE_SIZE-1, "%d\n", pmu->type);
5348}
5349
5350static struct device_attribute pmu_dev_attrs[] = {
5351       __ATTR_RO(type),
5352       __ATTR_NULL,
5353};
5354
5355static int pmu_bus_running;
5356static struct bus_type pmu_bus = {
5357    .name = "event_source",
5358    .dev_attrs = pmu_dev_attrs,
5359};
5360
5361static void pmu_dev_release(struct device *dev)
5362{
5363    kfree(dev);
5364}
5365
5366static int pmu_dev_alloc(struct pmu *pmu)
5367{
5368    int ret = -ENOMEM;
5369
5370    pmu->dev = kzalloc(sizeof(struct device), GFP_KERNEL);
5371    if (!pmu->dev)
5372        goto out;
5373
5374    device_initialize(pmu->dev);
5375    ret = dev_set_name(pmu->dev, "%s", pmu->name);
5376    if (ret)
5377        goto free_dev;
5378
5379    dev_set_drvdata(pmu->dev, pmu);
5380    pmu->dev->bus = &pmu_bus;
5381    pmu->dev->release = pmu_dev_release;
5382    ret = device_add(pmu->dev);
5383    if (ret)
5384        goto free_dev;
5385
5386out:
5387    return ret;
5388
5389free_dev:
5390    put_device(pmu->dev);
5391    goto out;
5392}
5393
5394static struct lock_class_key cpuctx_mutex;
5395
5396int perf_pmu_register(struct pmu *pmu, char *name, int type)
5397{
5398    int cpu, ret;
5399
5400    mutex_lock(&pmus_lock);
5401    ret = -ENOMEM;
5402    pmu->pmu_disable_count = alloc_percpu(int);
5403    if (!pmu->pmu_disable_count)
5404        goto unlock;
5405
5406    pmu->type = -1;
5407    if (!name)
5408        goto skip_type;
5409    pmu->name = name;
5410
5411    if (type < 0) {
5412        int err = idr_pre_get(&pmu_idr, GFP_KERNEL);
5413        if (!err)
5414            goto free_pdc;
5415
5416        err = idr_get_new_above(&pmu_idr, pmu, PERF_TYPE_MAX, &type);
5417        if (err) {
5418            ret = err;
5419            goto free_pdc;
5420        }
5421    }
5422    pmu->type = type;
5423
5424    if (pmu_bus_running) {
5425        ret = pmu_dev_alloc(pmu);
5426        if (ret)
5427            goto free_idr;
5428    }
5429
5430skip_type:
5431    pmu->pmu_cpu_context = find_pmu_context(pmu->task_ctx_nr);
5432    if (pmu->pmu_cpu_context)
5433        goto got_cpu_context;
5434
5435    pmu->pmu_cpu_context = alloc_percpu(struct perf_cpu_context);
5436    if (!pmu->pmu_cpu_context)
5437        goto free_dev;
5438
5439    for_each_possible_cpu(cpu) {
5440        struct perf_cpu_context *cpuctx;
5441
5442        cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
5443        __perf_event_init_context(&cpuctx->ctx);
5444        lockdep_set_class(&cpuctx->ctx.mutex, &cpuctx_mutex);
5445        cpuctx->ctx.type = cpu_context;
5446        cpuctx->ctx.pmu = pmu;
5447        cpuctx->jiffies_interval = 1;
5448        INIT_LIST_HEAD(&cpuctx->rotation_list);
5449        cpuctx->active_pmu = pmu;
5450    }
5451
5452got_cpu_context:
5453    if (!pmu->start_txn) {
5454        if (pmu->pmu_enable) {
5455            /*
5456             * If we have pmu_enable/pmu_disable calls, install
5457             * transaction stubs that use that to try and batch
5458             * hardware accesses.
5459             */
5460            pmu->start_txn = perf_pmu_start_txn;
5461            pmu->commit_txn = perf_pmu_commit_txn;
5462            pmu->cancel_txn = perf_pmu_cancel_txn;
5463        } else {
5464            pmu->start_txn = perf_pmu_nop_void;
5465            pmu->commit_txn = perf_pmu_nop_int;
5466            pmu->cancel_txn = perf_pmu_nop_void;
5467        }
5468    }
5469
5470    if (!pmu->pmu_enable) {
5471        pmu->pmu_enable = perf_pmu_nop_void;
5472        pmu->pmu_disable = perf_pmu_nop_void;
5473    }
5474
5475    list_add_rcu(&pmu->entry, &pmus);
5476    ret = 0;
5477unlock:
5478    mutex_unlock(&pmus_lock);
5479
5480    return ret;
5481
5482free_dev:
5483    device_del(pmu->dev);
5484    put_device(pmu->dev);
5485
5486free_idr:
5487    if (pmu->type >= PERF_TYPE_MAX)
5488        idr_remove(&pmu_idr, pmu->type);
5489
5490free_pdc:
5491    free_percpu(pmu->pmu_disable_count);
5492    goto unlock;
5493}
5494
5495void perf_pmu_unregister(struct pmu *pmu)
5496{
5497    mutex_lock(&pmus_lock);
5498    list_del_rcu(&pmu->entry);
5499    mutex_unlock(&pmus_lock);
5500
5501    /*
5502     * We dereference the pmu list under both SRCU and regular RCU, so
5503     * synchronize against both of those.
5504     */
5505    synchronize_srcu(&pmus_srcu);
5506    synchronize_rcu();
5507
5508    free_percpu(pmu->pmu_disable_count);
5509    if (pmu->type >= PERF_TYPE_MAX)
5510        idr_remove(&pmu_idr, pmu->type);
5511    device_del(pmu->dev);
5512    put_device(pmu->dev);
5513    free_pmu_context(pmu);
5514}
5515
5516struct pmu *perf_init_event(struct perf_event *event)
5517{
5518    struct pmu *pmu = NULL;
5519    int idx;
5520
5521    idx = srcu_read_lock(&pmus_srcu);
5522
5523    rcu_read_lock();
5524    pmu = idr_find(&pmu_idr, event->attr.type);
5525    rcu_read_unlock();
5526    if (pmu)
5527        goto unlock;
5528
5529    list_for_each_entry_rcu(pmu, &pmus, entry) {
5530        int ret = pmu->event_init(event);
5531        if (!ret)
5532            goto unlock;
5533
5534        if (ret != -ENOENT) {
5535            pmu = ERR_PTR(ret);
5536            goto unlock;
5537        }
5538    }
5539    pmu = ERR_PTR(-ENOENT);
5540unlock:
5541    srcu_read_unlock(&pmus_srcu, idx);
5542
5543    return pmu;
5544}
5545
5546/*
5547 * Allocate and initialize a event structure
5548 */
5549static struct perf_event *
5550perf_event_alloc(struct perf_event_attr *attr, int cpu,
5551         struct task_struct *task,
5552         struct perf_event *group_leader,
5553         struct perf_event *parent_event,
5554         perf_overflow_handler_t overflow_handler)
5555{
5556    struct pmu *pmu;
5557    struct perf_event *event;
5558    struct hw_perf_event *hwc;
5559    long err;
5560
5561    if ((unsigned)cpu >= nr_cpu_ids) {
5562        if (!task || cpu != -1)
5563            return ERR_PTR(-EINVAL);
5564    }
5565
5566    event = kzalloc(sizeof(*event), GFP_KERNEL);
5567    if (!event)
5568        return ERR_PTR(-ENOMEM);
5569
5570    /*
5571     * Single events are their own group leaders, with an
5572     * empty sibling list:
5573     */
5574    if (!group_leader)
5575        group_leader = event;
5576
5577    mutex_init(&event->child_mutex);
5578    INIT_LIST_HEAD(&event->child_list);
5579
5580    INIT_LIST_HEAD(&event->group_entry);
5581    INIT_LIST_HEAD(&event->event_entry);
5582    INIT_LIST_HEAD(&event->sibling_list);
5583    init_waitqueue_head(&event->waitq);
5584    init_irq_work(&event->pending, perf_pending_event);
5585
5586    mutex_init(&event->mmap_mutex);
5587
5588    event->cpu = cpu;
5589    event->attr = *attr;
5590    event->group_leader = group_leader;
5591    event->pmu = NULL;
5592    event->oncpu = -1;
5593
5594    event->parent = parent_event;
5595
5596    event->ns = get_pid_ns(current->nsproxy->pid_ns);
5597    event->id = atomic64_inc_return(&perf_event_id);
5598
5599    event->state = PERF_EVENT_STATE_INACTIVE;
5600
5601    if (task) {
5602        event->attach_state = PERF_ATTACH_TASK;
5603#ifdef CONFIG_HAVE_HW_BREAKPOINT
5604        /*
5605         * hw_breakpoint is a bit difficult here..
5606         */
5607        if (attr->type == PERF_TYPE_BREAKPOINT)
5608            event->hw.bp_target = task;
5609#endif
5610    }
5611
5612    if (!overflow_handler && parent_event)
5613        overflow_handler = parent_event->overflow_handler;
5614
5615    event->overflow_handler = overflow_handler;
5616
5617    if (attr->disabled)
5618        event->state = PERF_EVENT_STATE_OFF;
5619
5620    pmu = NULL;
5621
5622    hwc = &event->hw;
5623    hwc->sample_period = attr->sample_period;
5624    if (attr->freq && attr->sample_freq)
5625        hwc->sample_period = 1;
5626    hwc->last_period = hwc->sample_period;
5627
5628    local64_set(&hwc->period_left, hwc->sample_period);
5629
5630    /*
5631     * we currently do not support PERF_FORMAT_GROUP on inherited events
5632     */
5633    if (attr->inherit && (attr->read_format & PERF_FORMAT_GROUP))
5634        goto done;
5635
5636    pmu = perf_init_event(event);
5637
5638done:
5639    err = 0;
5640    if (!pmu)
5641        err = -EINVAL;
5642    else if (IS_ERR(pmu))
5643        err = PTR_ERR(pmu);
5644
5645    if (err) {
5646        if (event->ns)
5647            put_pid_ns(event->ns);
5648        kfree(event);
5649        return ERR_PTR(err);
5650    }
5651
5652    event->pmu = pmu;
5653
5654    if (!event->parent) {
5655        if (event->attach_state & PERF_ATTACH_TASK)
5656            jump_label_inc(&perf_task_events);
5657        if (event->attr.mmap || event->attr.mmap_data)
5658            atomic_inc(&nr_mmap_events);
5659        if (event->attr.comm)
5660            atomic_inc(&nr_comm_events);
5661        if (event->attr.task)
5662            atomic_inc(&nr_task_events);
5663        if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) {
5664            err = get_callchain_buffers();
5665            if (err) {
5666                free_event(event);
5667                return ERR_PTR(err);
5668            }
5669        }
5670    }
5671
5672    return event;
5673}
5674
5675static int perf_copy_attr(struct perf_event_attr __user *uattr,
5676              struct perf_event_attr *attr)
5677{
5678    u32 size;
5679    int ret;
5680
5681    if (!access_ok(VERIFY_WRITE, uattr, PERF_ATTR_SIZE_VER0))
5682        return -EFAULT;
5683
5684    /*
5685     * zero the full structure, so that a short copy will be nice.
5686     */
5687    memset(attr, 0, sizeof(*attr));
5688
5689    ret = get_user(size, &uattr->size);
5690    if (ret)
5691        return ret;
5692
5693    if (size > PAGE_SIZE) /* silly large */
5694        goto err_size;
5695
5696    if (!size) /* abi compat */
5697        size = PERF_ATTR_SIZE_VER0;
5698
5699    if (size < PERF_ATTR_SIZE_VER0)
5700        goto err_size;
5701
5702    /*
5703     * If we're handed a bigger struct than we know of,
5704     * ensure all the unknown bits are 0 - i.e. new
5705     * user-space does not rely on any kernel feature
5706     * extensions we dont know about yet.
5707     */
5708    if (size > sizeof(*attr)) {
5709        unsigned char __user *addr;
5710        unsigned char __user *end;
5711        unsigned char val;
5712
5713        addr = (void __user *)uattr + sizeof(*attr);
5714        end = (void __user *)uattr + size;
5715
5716        for (; addr < end; addr++) {
5717            ret = get_user(val, addr);
5718            if (ret)
5719                return ret;
5720            if (val)
5721                goto err_size;
5722        }
5723        size = sizeof(*attr);
5724    }
5725
5726    ret = copy_from_user(attr, uattr, size);
5727    if (ret)
5728        return -EFAULT;
5729
5730    /*
5731     * If the type exists, the corresponding creation will verify
5732     * the attr->config.
5733     */
5734    if (attr->type >= PERF_TYPE_MAX)
5735        return -EINVAL;
5736
5737    if (attr->__reserved_1)
5738        return -EINVAL;
5739
5740    if (attr->sample_type & ~(PERF_SAMPLE_MAX-1))
5741        return -EINVAL;
5742
5743    if (attr->read_format & ~(PERF_FORMAT_MAX-1))
5744        return -EINVAL;
5745
5746out:
5747    return ret;
5748
5749err_size:
5750    put_user(sizeof(*attr), &uattr->size);
5751    ret = -E2BIG;
5752    goto out;
5753}
5754
5755static int
5756perf_event_set_output(struct perf_event *event, struct perf_event *output_event)
5757{
5758    struct perf_buffer *buffer = NULL, *old_buffer = NULL;
5759    int ret = -EINVAL;
5760
5761    if (!output_event)
5762        goto set;
5763
5764    /* don't allow circular references */
5765    if (event == output_event)
5766        goto out;
5767
5768    /*
5769     * Don't allow cross-cpu buffers
5770     */
5771    if (output_event->cpu != event->cpu)
5772        goto out;
5773
5774    /*
5775     * If its not a per-cpu buffer, it must be the same task.
5776     */
5777    if (output_event->cpu == -1 && output_event->ctx != event->ctx)
5778        goto out;
5779
5780set:
5781    mutex_lock(&event->mmap_mutex);
5782    /* Can't redirect output if we've got an active mmap() */
5783    if (atomic_read(&event->mmap_count))
5784        goto unlock;
5785
5786    if (output_event) {
5787        /* get the buffer we want to redirect to */
5788        buffer = perf_buffer_get(output_event);
5789        if (!buffer)
5790            goto unlock;
5791    }
5792
5793    old_buffer = event->buffer;
5794    rcu_assign_pointer(event->buffer, buffer);
5795    ret = 0;
5796unlock:
5797    mutex_unlock(&event->mmap_mutex);
5798
5799    if (old_buffer)
5800        perf_buffer_put(old_buffer);
5801out:
5802    return ret;
5803}
5804
5805/**
5806 * sys_perf_event_open - open a performance event, associate it to a task/cpu
5807 *
5808 * @attr_uptr: event_id type attributes for monitoring/sampling
5809 * @pid: target pid
5810 * @cpu: target cpu
5811 * @group_fd: group leader event fd
5812 */
5813SYSCALL_DEFINE5(perf_event_open,
5814        struct perf_event_attr __user *, attr_uptr,
5815        pid_t, pid, int, cpu, int, group_fd, unsigned long, flags)
5816{
5817    struct perf_event *group_leader = NULL, *output_event = NULL;
5818    struct perf_event *event, *sibling;
5819    struct perf_event_attr attr;
5820    struct perf_event_context *ctx;
5821    struct file *event_file = NULL;
5822    struct file *group_file = NULL;
5823    struct task_struct *task = NULL;
5824    struct pmu *pmu;
5825    int event_fd;
5826    int move_group = 0;
5827    int fput_needed = 0;
5828    int err;
5829
5830    /* for future expandability... */
5831    if (flags & ~(PERF_FLAG_FD_NO_GROUP | PERF_FLAG_FD_OUTPUT))
5832        return -EINVAL;
5833
5834    err = perf_copy_attr(attr_uptr, &attr);
5835    if (err)
5836        return err;
5837
5838    if (!attr.exclude_kernel) {
5839        if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
5840            return -EACCES;
5841    }
5842
5843    if (attr.freq) {
5844        if (attr.sample_freq > sysctl_perf_event_sample_rate)
5845            return -EINVAL;
5846    }
5847
5848    event_fd = get_unused_fd_flags(O_RDWR);
5849    if (event_fd < 0)
5850        return event_fd;
5851
5852    if (group_fd != -1) {
5853        group_leader = perf_fget_light(group_fd, &fput_needed);
5854        if (IS_ERR(group_leader)) {
5855            err = PTR_ERR(group_leader);
5856            goto err_fd;
5857        }
5858        group_file = group_leader->filp;
5859        if (flags & PERF_FLAG_FD_OUTPUT)
5860            output_event = group_leader;
5861        if (flags & PERF_FLAG_FD_NO_GROUP)
5862            group_leader = NULL;
5863    }
5864
5865    if (pid != -1) {
5866        task = find_lively_task_by_vpid(pid);
5867        if (IS_ERR(task)) {
5868            err = PTR_ERR(task);
5869            goto err_group_fd;
5870        }
5871    }
5872
5873    event = perf_event_alloc(&attr, cpu, task, group_leader, NULL, NULL);
5874    if (IS_ERR(event)) {
5875        err = PTR_ERR(event);
5876        goto err_task;
5877    }
5878
5879    /*
5880     * Special case software events and allow them to be part of
5881     * any hardware group.
5882     */
5883    pmu = event->pmu;
5884
5885    if (group_leader &&
5886        (is_software_event(event) != is_software_event(group_leader))) {
5887        if (is_software_event(event)) {
5888            /*
5889             * If event and group_leader are not both a software
5890             * event, and event is, then group leader is not.
5891             *
5892             * Allow the addition of software events to !software
5893             * groups, this is safe because software events never
5894             * fail to schedule.
5895             */
5896            pmu = group_leader->pmu;
5897        } else if (is_software_event(group_leader) &&
5898               (group_leader->group_flags & PERF_GROUP_SOFTWARE)) {
5899            /*
5900             * In case the group is a pure software group, and we
5901             * try to add a hardware event, move the whole group to
5902             * the hardware context.
5903             */
5904            move_group = 1;
5905        }
5906    }
5907
5908    /*
5909     * Get the target context (task or percpu):
5910     */
5911    ctx = find_get_context(pmu, task, cpu);
5912    if (IS_ERR(ctx)) {
5913        err = PTR_ERR(ctx);
5914        goto err_alloc;
5915    }
5916
5917    /*
5918     * Look up the group leader (we will attach this event to it):
5919     */
5920    if (group_leader) {
5921        err = -EINVAL;
5922
5923        /*
5924         * Do not allow a recursive hierarchy (this new sibling
5925         * becoming part of another group-sibling):
5926         */
5927        if (group_leader->group_leader != group_leader)
5928            goto err_context;
5929        /*
5930         * Do not allow to attach to a group in a different
5931         * task or CPU context:
5932         */
5933        if (move_group) {
5934            if (group_leader->ctx->type != ctx->type)
5935                goto err_context;
5936        } else {
5937            if (group_leader->ctx != ctx)
5938                goto err_context;
5939        }
5940
5941        /*
5942         * Only a group leader can be exclusive or pinned
5943         */
5944        if (attr.exclusive || attr.pinned)
5945            goto err_context;
5946    }
5947
5948    if (output_event) {
5949        err = perf_event_set_output(event, output_event);
5950        if (err)
5951            goto err_context;
5952    }
5953
5954    event_file = anon_inode_getfile("[perf_event]", &perf_fops, event, O_RDWR);
5955    if (IS_ERR(event_file)) {
5956        err = PTR_ERR(event_file);
5957        goto err_context;
5958    }
5959
5960    if (move_group) {
5961        struct perf_event_context *gctx = group_leader->ctx;
5962
5963        mutex_lock(&gctx->mutex);
5964        perf_event_remove_from_context(group_leader);
5965        list_for_each_entry(sibling, &group_leader->sibling_list,
5966                    group_entry) {
5967            perf_event_remove_from_context(sibling);
5968            put_ctx(gctx);
5969        }
5970        mutex_unlock(&gctx->mutex);
5971        put_ctx(gctx);
5972    }
5973
5974    event->filp = event_file;
5975    WARN_ON_ONCE(ctx->parent_ctx);
5976    mutex_lock(&ctx->mutex);
5977
5978    if (move_group) {
5979        perf_install_in_context(ctx, group_leader, cpu);
5980        get_ctx(ctx);
5981        list_for_each_entry(sibling, &group_leader->sibling_list,
5982                    group_entry) {
5983            perf_install_in_context(ctx, sibling, cpu);
5984            get_ctx(ctx);
5985        }
5986    }
5987
5988    perf_install_in_context(ctx, event, cpu);
5989    ++ctx->generation;
5990    mutex_unlock(&ctx->mutex);
5991
5992    event->owner = current;
5993
5994    mutex_lock(&current->perf_event_mutex);
5995    list_add_tail(&event->owner_entry, &current->perf_event_list);
5996    mutex_unlock(&current->perf_event_mutex);
5997
5998    /*
5999     * Precalculate sample_data sizes
6000     */
6001    perf_event__header_size(event);
6002    perf_event__id_header_size(event);
6003
6004    /*
6005     * Drop the reference on the group_event after placing the
6006     * new event on the sibling_list. This ensures destruction
6007     * of the group leader will find the pointer to itself in
6008     * perf_group_detach().
6009     */
6010    fput_light(group_file, fput_needed);
6011    fd_install(event_fd, event_file);
6012    return event_fd;
6013
6014err_context:
6015    put_ctx(ctx);
6016err_alloc:
6017    free_event(event);
6018err_task:
6019    if (task)
6020        put_task_struct(task);
6021err_group_fd:
6022    fput_light(group_file, fput_needed);
6023err_fd:
6024    put_unused_fd(event_fd);
6025    return err;
6026}
6027
6028/**
6029 * perf_event_create_kernel_counter
6030 *
6031 * @attr: attributes of the counter to create
6032 * @cpu: cpu in which the counter is bound
6033 * @task: task to profile (NULL for percpu)
6034 */
6035struct perf_event *
6036perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
6037                 struct task_struct *task,
6038                 perf_overflow_handler_t overflow_handler)
6039{
6040    struct perf_event_context *ctx;
6041    struct perf_event *event;
6042    int err;
6043
6044    /*
6045     * Get the target context (task or percpu):
6046     */
6047
6048    event = perf_event_alloc(attr, cpu, task, NULL, NULL, overflow_handler);
6049    if (IS_ERR(event)) {
6050        err = PTR_ERR(event);
6051        goto err;
6052    }
6053
6054    ctx = find_get_context(event->pmu, task, cpu);
6055    if (IS_ERR(ctx)) {
6056        err = PTR_ERR(ctx);
6057        goto err_free;
6058    }
6059
6060    event->filp = NULL;
6061    WARN_ON_ONCE(ctx->parent_ctx);
6062    mutex_lock(&ctx->mutex);
6063    perf_install_in_context(ctx, event, cpu);
6064    ++ctx->generation;
6065    mutex_unlock(&ctx->mutex);
6066
6067    return event;
6068
6069err_free:
6070    free_event(event);
6071err:
6072    return ERR_PTR(err);
6073}
6074EXPORT_SYMBOL_GPL(perf_event_create_kernel_counter);
6075
6076static void sync_child_event(struct perf_event *child_event,
6077                   struct task_struct *child)
6078{
6079    struct perf_event *parent_event = child_event->parent;
6080    u64 child_val;
6081
6082    if (child_event->attr.inherit_stat)
6083        perf_event_read_event(child_event, child);
6084
6085    child_val = perf_event_count(child_event);
6086
6087    /*
6088     * Add back the child's count to the parent's count:
6089     */
6090    atomic64_add(child_val, &parent_event->child_count);
6091    atomic64_add(child_event->total_time_enabled,
6092             &parent_event->child_total_time_enabled);
6093    atomic64_add(child_event->total_time_running,
6094             &parent_event->child_total_time_running);
6095
6096    /*
6097     * Remove this event from the parent's list
6098     */
6099    WARN_ON_ONCE(parent_event->ctx->parent_ctx);
6100    mutex_lock(&parent_event->child_mutex);
6101    list_del_init(&child_event->child_list);
6102    mutex_unlock(&parent_event->child_mutex);
6103
6104    /*
6105     * Release the parent event, if this was the last
6106     * reference to it.
6107     */
6108    fput(parent_event->filp);
6109}
6110
6111static void
6112__perf_event_exit_task(struct perf_event *child_event,
6113             struct perf_event_context *child_ctx,
6114             struct task_struct *child)
6115{
6116    struct perf_event *parent_event;
6117
6118    perf_event_remove_from_context(child_event);
6119
6120    parent_event = child_event->parent;
6121    /*
6122     * It can happen that parent exits first, and has events
6123     * that are still around due to the child reference. These
6124     * events need to be zapped - but otherwise linger.
6125     */
6126    if (parent_event) {
6127        sync_child_event(child_event, child);
6128        free_event(child_event);
6129    }
6130}
6131
6132static void perf_event_exit_task_context(struct task_struct *child, int ctxn)
6133{
6134    struct perf_event *child_event, *tmp;
6135    struct perf_event_context *child_ctx;
6136    unsigned long flags;
6137
6138    if (likely(!child->perf_event_ctxp[ctxn])) {
6139        perf_event_task(child, NULL, 0);
6140        return;
6141    }
6142
6143    local_irq_save(flags);
6144    /*
6145     * We can't reschedule here because interrupts are disabled,
6146     * and either child is current or it is a task that can't be
6147     * scheduled, so we are now safe from rescheduling changing
6148     * our context.
6149     */
6150    child_ctx = rcu_dereference_raw(child->perf_event_ctxp[ctxn]);
6151    task_ctx_sched_out(child_ctx, EVENT_ALL);
6152
6153    /*