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1 #undef DEBUG
2
3 /*
4 * ARM performance counter support.
5 *
6 * Copyright (C) 2009 picoChip Designs, Ltd., Jamie Iles
7 * Copyright (C) 2010 ARM Ltd., Will Deacon <will.deacon@arm.com>
8 *
9 * This code is based on the sparc64 perf event code, which is in turn based
10 * on the x86 code. Callchain code is based on the ARM OProfile backtrace
11 * code.
12 */
13 #define pr_fmt(fmt) "hw perfevents: " fmt
14
15 #include <linux/bitmap.h>
16 #include <linux/interrupt.h>
17 #include <linux/kernel.h>
18 #include <linux/export.h>
19 #include <linux/perf_event.h>
20 #include <linux/platform_device.h>
21 #include <linux/spinlock.h>
22 #include <linux/uaccess.h>
23
24 #include <asm/cputype.h>
25 #include <asm/irq.h>
26 #include <asm/irq_regs.h>
27 #include <asm/pmu.h>
28 #include <asm/stacktrace.h>
29
30 /*
31 * ARMv6 supports a maximum of 3 events, starting from index 0. If we add
32 * another platform that supports more, we need to increase this to be the
33 * largest of all platforms.
34 *
35 * ARMv7 supports up to 32 events:
36 * cycle counter CCNT + 31 events counters CNT0..30.
37 * Cortex-A8 has 1+4 counters, Cortex-A9 has 1+6 counters.
38 */
39 #define ARMPMU_MAX_HWEVENTS 32
40
41 static DEFINE_PER_CPU(struct perf_event * [ARMPMU_MAX_HWEVENTS], hw_events);
42 static DEFINE_PER_CPU(unsigned long [BITS_TO_LONGS(ARMPMU_MAX_HWEVENTS)], used_mask);
43 static DEFINE_PER_CPU(struct pmu_hw_events, cpu_hw_events);
44
45 #define to_arm_pmu(p) (container_of(p, struct arm_pmu, pmu))
46
47 /* Set at runtime when we know what CPU type we are. */
48 static struct arm_pmu *cpu_pmu;
49
50 enum arm_perf_pmu_ids
51 armpmu_get_pmu_id(void)
52 {
53 int id = -ENODEV;
54
55 if (cpu_pmu != NULL)
56 id = cpu_pmu->id;
57
58 return id;
59 }
60 EXPORT_SYMBOL_GPL(armpmu_get_pmu_id);
61
62 int perf_num_counters(void)
63 {
64 int max_events = 0;
65
66 if (cpu_pmu != NULL)
67 max_events = cpu_pmu->num_events;
68
69 return max_events;
70 }
71 EXPORT_SYMBOL_GPL(perf_num_counters);
72
73 #define HW_OP_UNSUPPORTED 0xFFFF
74
75 #define C(_x) \
76 PERF_COUNT_HW_CACHE_##_x
77
78 #define CACHE_OP_UNSUPPORTED 0xFFFF
79
80 static int
81 armpmu_map_cache_event(const unsigned (*cache_map)
82 [PERF_COUNT_HW_CACHE_MAX]
83 [PERF_COUNT_HW_CACHE_OP_MAX]
84 [PERF_COUNT_HW_CACHE_RESULT_MAX],
85 u64 config)
86 {
87 unsigned int cache_type, cache_op, cache_result, ret;
88
89 cache_type = (config >> 0) & 0xff;
90 if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
91 return -EINVAL;
92
93 cache_op = (config >> 8) & 0xff;
94 if (cache_op >= PERF_COUNT_HW_CACHE_OP_MAX)
95 return -EINVAL;
96
97 cache_result = (config >> 16) & 0xff;
98 if (cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
99 return -EINVAL;
100
101 ret = (int)(*cache_map)[cache_type][cache_op][cache_result];
102
103 if (ret == CACHE_OP_UNSUPPORTED)
104 return -ENOENT;
105
106 return ret;
107 }
108
109 static int
110 armpmu_map_event(const unsigned (*event_map)[PERF_COUNT_HW_MAX], u64 config)
111 {
112 int mapping = (*event_map)[config];
113 return mapping == HW_OP_UNSUPPORTED ? -ENOENT : mapping;
114 }
115
116 static int
117 armpmu_map_raw_event(u32 raw_event_mask, u64 config)
118 {
119 return (int)(config & raw_event_mask);
120 }
121
122 static int map_cpu_event(struct perf_event *event,
123 const unsigned (*event_map)[PERF_COUNT_HW_MAX],
124 const unsigned (*cache_map)
125 [PERF_COUNT_HW_CACHE_MAX]
126 [PERF_COUNT_HW_CACHE_OP_MAX]
127 [PERF_COUNT_HW_CACHE_RESULT_MAX],
128 u32 raw_event_mask)
129 {
130 u64 config = event->attr.config;
131
132 switch (event->attr.type) {
133 case PERF_TYPE_HARDWARE:
134 return armpmu_map_event(event_map, config);
135 case PERF_TYPE_HW_CACHE:
136 return armpmu_map_cache_event(cache_map, config);
137 case PERF_TYPE_RAW:
138 return armpmu_map_raw_event(raw_event_mask, config);
139 }
140
141 return -ENOENT;
142 }
143
144 int
145 armpmu_event_set_period(struct perf_event *event,
146 struct hw_perf_event *hwc,
147 int idx)
148 {
149 struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
150 s64 left = local64_read(&hwc->period_left);
151 s64 period = hwc->sample_period;
152 int ret = 0;
153
154 if (unlikely(left <= -period)) {
155 left = period;
156 local64_set(&hwc->period_left, left);
157 hwc->last_period = period;
158 ret = 1;
159 }
160
161 if (unlikely(left <= 0)) {
162 left += period;
163 local64_set(&hwc->period_left, left);
164 hwc->last_period = period;
165 ret = 1;
166 }
167
168 if (left > (s64)armpmu->max_period)
169 left = armpmu->max_period;
170
171 local64_set(&hwc->prev_count, (u64)-left);
172
173 armpmu->write_counter(idx, (u64)(-left) & 0xffffffff);
174
175 perf_event_update_userpage(event);
176
177 return ret;
178 }
179
180 u64
181 armpmu_event_update(struct perf_event *event,
182 struct hw_perf_event *hwc,
183 int idx, int overflow)
184 {
185 struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
186 u64 delta, prev_raw_count, new_raw_count;
187
188 again:
189 prev_raw_count = local64_read(&hwc->prev_count);
190 new_raw_count = armpmu->read_counter(idx);
191
192 if (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
193 new_raw_count) != prev_raw_count)
194 goto again;
195
196 new_raw_count &= armpmu->max_period;
197 prev_raw_count &= armpmu->max_period;
198
199 if (overflow)
200 delta = armpmu->max_period - prev_raw_count + new_raw_count + 1;
201 else
202 delta = new_raw_count - prev_raw_count;
203
204 local64_add(delta, &event->count);
205 local64_sub(delta, &hwc->period_left);
206
207 return new_raw_count;
208 }
209
210 static void
211 armpmu_read(struct perf_event *event)
212 {
213 struct hw_perf_event *hwc = &event->hw;
214
215 /* Don't read disabled counters! */
216 if (hwc->idx < 0)
217 return;
218
219 armpmu_event_update(event, hwc, hwc->idx, 0);
220 }
221
222 static void
223 armpmu_stop(struct perf_event *event, int flags)
224 {
225 struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
226 struct hw_perf_event *hwc = &event->hw;
227
228 /*
229 * ARM pmu always has to update the counter, so ignore
230 * PERF_EF_UPDATE, see comments in armpmu_start().
231 */
232 if (!(hwc->state & PERF_HES_STOPPED)) {
233 armpmu->disable(hwc, hwc->idx);
234 barrier(); /* why? */
235 armpmu_event_update(event, hwc, hwc->idx, 0);
236 hwc->state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
237 }
238 }
239
240 static void
241 armpmu_start(struct perf_event *event, int flags)
242 {
243 struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
244 struct hw_perf_event *hwc = &event->hw;
245
246 /*
247 * ARM pmu always has to reprogram the period, so ignore
248 * PERF_EF_RELOAD, see the comment below.
249 */
250 if (flags & PERF_EF_RELOAD)
251 WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE));
252
253 hwc->state = 0;
254 /*
255 * Set the period again. Some counters can't be stopped, so when we
256 * were stopped we simply disabled the IRQ source and the counter
257 * may have been left counting. If we don't do this step then we may
258 * get an interrupt too soon or *way* too late if the overflow has
259 * happened since disabling.
260 */
261 armpmu_event_set_period(event, hwc, hwc->idx);
262 armpmu->enable(hwc, hwc->idx);
263 }
264
265 static void
266 armpmu_del(struct perf_event *event, int flags)
267 {
268 struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
269 struct pmu_hw_events *hw_events = armpmu->get_hw_events();
270 struct hw_perf_event *hwc = &event->hw;
271 int idx = hwc->idx;
272
273 WARN_ON(idx < 0);
274
275 armpmu_stop(event, PERF_EF_UPDATE);
276 hw_events->events[idx] = NULL;
277 clear_bit(idx, hw_events->used_mask);
278
279 perf_event_update_userpage(event);
280 }
281
282 static int
283 armpmu_add(struct perf_event *event, int flags)
284 {
285 struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
286 struct pmu_hw_events *hw_events = armpmu->get_hw_events();
287 struct hw_perf_event *hwc = &event->hw;
288 int idx;
289 int err = 0;
290
291 perf_pmu_disable(event->pmu);
292
293 /* If we don't have a space for the counter then finish early. */
294 idx = armpmu->get_event_idx(hw_events, hwc);
295 if (idx < 0) {
296 err = idx;
297 goto out;
298 }
299
300 /*
301 * If there is an event in the counter we are going to use then make
302 * sure it is disabled.
303 */
304 event->hw.idx = idx;
305 armpmu->disable(hwc, idx);
306 hw_events->events[idx] = event;
307
308 hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
309 if (flags & PERF_EF_START)
310 armpmu_start(event, PERF_EF_RELOAD);
311
312 /* Propagate our changes to the userspace mapping. */
313 perf_event_update_userpage(event);
314
315 out:
316 perf_pmu_enable(event->pmu);
317 return err;
318 }
319
320 static int
321 validate_event(struct pmu_hw_events *hw_events,
322 struct perf_event *event)
323 {
324 struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
325 struct hw_perf_event fake_event = event->hw;
326 struct pmu *leader_pmu = event->group_leader->pmu;
327
328 if (event->pmu != leader_pmu || event->state <= PERF_EVENT_STATE_OFF)
329 return 1;
330
331 return armpmu->get_event_idx(hw_events, &fake_event) >= 0;
332 }
333
334 static int
335 validate_group(struct perf_event *event)
336 {
337 struct perf_event *sibling, *leader = event->group_leader;
338 struct pmu_hw_events fake_pmu;
339 DECLARE_BITMAP(fake_used_mask, ARMPMU_MAX_HWEVENTS);
340
341 /*
342 * Initialise the fake PMU. We only need to populate the
343 * used_mask for the purposes of validation.
344 */
345 memset(fake_used_mask, 0, sizeof(fake_used_mask));
346 fake_pmu.used_mask = fake_used_mask;
347
348 if (!validate_event(&fake_pmu, leader))
349 return -EINVAL;
350
351 list_for_each_entry(sibling, &leader->sibling_list, group_entry) {
352 if (!validate_event(&fake_pmu, sibling))
353 return -EINVAL;
354 }
355
356 if (!validate_event(&fake_pmu, event))
357 return -EINVAL;
358
359 return 0;
360 }
361
362 static irqreturn_t armpmu_platform_irq(int irq, void *dev)
363 {
364 struct arm_pmu *armpmu = (struct arm_pmu *) dev;
365 struct platform_device *plat_device = armpmu->plat_device;
366 struct arm_pmu_platdata *plat = dev_get_platdata(&plat_device->dev);
367
368 return plat->handle_irq(irq, dev, armpmu->handle_irq);
369 }
370
371 static void
372 armpmu_release_hardware(struct arm_pmu *armpmu)
373 {
374 int i, irq, irqs;
375 struct platform_device *pmu_device = armpmu->plat_device;
376 struct arm_pmu_platdata *plat =
377 dev_get_platdata(&pmu_device->dev);
378
379 irqs = min(pmu_device->num_resources, num_possible_cpus());
380
381 for (i = 0; i < irqs; ++i) {
382 if (!cpumask_test_and_clear_cpu(i, &armpmu->active_irqs))
383 continue;
384 irq = platform_get_irq(pmu_device, i);
385 if (irq >= 0) {
386 if (plat && plat->disable_irq)
387 plat->disable_irq(irq);
388 free_irq(irq, armpmu);
389 }
390 }
391
392 release_pmu(armpmu->type);
393 }
394
395 static int
396 armpmu_reserve_hardware(struct arm_pmu *armpmu)
397 {
398 struct arm_pmu_platdata *plat;
399 irq_handler_t handle_irq;
400 int i, err, irq, irqs;
401 struct platform_device *pmu_device = armpmu->plat_device;
402
403 if (!pmu_device)
404 return -ENODEV;
405
406 err = reserve_pmu(armpmu->type);
407 if (err) {
408 pr_warning("unable to reserve pmu\n");
409 return err;
410 }
411
412 plat = dev_get_platdata(&pmu_device->dev);
413 if (plat && plat->handle_irq)
414 handle_irq = armpmu_platform_irq;
415 else
416 handle_irq = armpmu->handle_irq;
417
418 irqs = min(pmu_device->num_resources, num_possible_cpus());
419 if (irqs < 1) {
420 pr_err("no irqs for PMUs defined\n");
421 return -ENODEV;
422 }
423
424 for (i = 0; i < irqs; ++i) {
425 err = 0;
426 irq = platform_get_irq(pmu_device, i);
427 if (irq < 0)
428 continue;
429
430 /*
431 * If we have a single PMU interrupt that we can't shift,
432 * assume that we're running on a uniprocessor machine and
433 * continue. Otherwise, continue without this interrupt.
434 */
435 if (irq_set_affinity(irq, cpumask_of(i)) && irqs > 1) {
436 pr_warning("unable to set irq affinity (irq=%d, cpu=%u)\n",
437 irq, i);
438 continue;
439 }
440
441 err = request_irq(irq, handle_irq,
442 IRQF_DISABLED | IRQF_NOBALANCING,
443 "arm-pmu", armpmu);
444 if (err) {
445 pr_err("unable to request IRQ%d for ARM PMU counters\n",
446 irq);
447 armpmu_release_hardware(armpmu);
448 return err;
449 } else if (plat && plat->enable_irq)
450 plat->enable_irq(irq);
451
452 cpumask_set_cpu(i, &armpmu->active_irqs);
453 }
454
455 return 0;
456 }
457
458 static void
459 hw_perf_event_destroy(struct perf_event *event)
460 {
461 struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
462 atomic_t *active_events = &armpmu->active_events;
463 struct mutex *pmu_reserve_mutex = &armpmu->reserve_mutex;
464
465 if (atomic_dec_and_mutex_lock(active_events, pmu_reserve_mutex)) {
466 armpmu_release_hardware(armpmu);
467 mutex_unlock(pmu_reserve_mutex);
468 }
469 }
470
471 static int
472 event_requires_mode_exclusion(struct perf_event_attr *attr)
473 {
474 return attr->exclude_idle || attr->exclude_user ||
475 attr->exclude_kernel || attr->exclude_hv;
476 }
477
478 static int
479 __hw_perf_event_init(struct perf_event *event)
480 {
481 struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
482 struct hw_perf_event *hwc = &event->hw;
483 int mapping, err;
484
485 mapping = armpmu->map_event(event);
486
487 if (mapping < 0) {
488 pr_debug("event %x:%llx not supported\n", event->attr.type,
489 event->attr.config);
490 return mapping;
491 }
492
493 /*
494 * We don't assign an index until we actually place the event onto
495 * hardware. Use -1 to signify that we haven't decided where to put it
496 * yet. For SMP systems, each core has it's own PMU so we can't do any
497 * clever allocation or constraints checking at this point.
498 */
499 hwc->idx = -1;
500 hwc->config_base = 0;
501 hwc->config = 0;
502 hwc->event_base = 0;
503
504 /*
505 * Check whether we need to exclude the counter from certain modes.
506 */
507 if ((!armpmu->set_event_filter ||
508 armpmu->set_event_filter(hwc, &event->attr)) &&
509 event_requires_mode_exclusion(&event->attr)) {
510 pr_debug("ARM performance counters do not support "
511 "mode exclusion\n");
512 return -EPERM;
513 }
514
515 /*
516 * Store the event encoding into the config_base field.
517 */
518 hwc->config_base |= (unsigned long)mapping;
519
520 if (!hwc->sample_period) {
521 hwc->sample_period = armpmu->max_period;
522 hwc->last_period = hwc->sample_period;
523 local64_set(&hwc->period_left, hwc->sample_period);
524 }
525
526 err = 0;
527 if (event->group_leader != event) {
528 err = validate_group(event);
529 if (err)
530 return -EINVAL;
531 }
532
533 return err;
534 }
535
536 static int armpmu_event_init(struct perf_event *event)
537 {
538 struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
539 int err = 0;
540 atomic_t *active_events = &armpmu->active_events;
541
542 if (armpmu->map_event(event) == -ENOENT)
543 return -ENOENT;
544
545 event->destroy = hw_perf_event_destroy;
546
547 if (!atomic_inc_not_zero(active_events)) {
548 mutex_lock(&armpmu->reserve_mutex);
549 if (atomic_read(active_events) == 0)
550 err = armpmu_reserve_hardware(armpmu);
551
552 if (!err)
553 atomic_inc(active_events);
554 mutex_unlock(&armpmu->reserve_mutex);
555 }
556
557 if (err)
558 return err;
559
560 err = __hw_perf_event_init(event);
561 if (err)
562 hw_perf_event_destroy(event);
563
564 return err;
565 }
566
567 static void armpmu_enable(struct pmu *pmu)
568 {
569 struct arm_pmu *armpmu = to_arm_pmu(pmu);
570 struct pmu_hw_events *hw_events = armpmu->get_hw_events();
571 int enabled = bitmap_weight(hw_events->used_mask, armpmu->num_events);
572
573 if (enabled)
574 armpmu->start();
575 }
576
577 static void armpmu_disable(struct pmu *pmu)
578 {
579 struct arm_pmu *armpmu = to_arm_pmu(pmu);
580 armpmu->stop();
581 }
582
583 static void __init armpmu_init(struct arm_pmu *armpmu)
584 {
585 atomic_set(&armpmu->active_events, 0);
586 mutex_init(&armpmu->reserve_mutex);
587
588 armpmu->pmu = (struct pmu) {
589 .pmu_enable = armpmu_enable,
590 .pmu_disable = armpmu_disable,
591 .event_init = armpmu_event_init,
592 .add = armpmu_add,
593 .del = armpmu_del,
594 .start = armpmu_start,
595 .stop = armpmu_stop,
596 .read = armpmu_read,
597 };
598 }
599
600 int __init armpmu_register(struct arm_pmu *armpmu, char *name, int type)
601 {
602 armpmu_init(armpmu);
603 return perf_pmu_register(&armpmu->pmu, name, type);
604 }
605
606 /* Include the PMU-specific implementations. */
607 #include "perf_event_xscale.c"
608 #include "perf_event_v6.c"
609 #include "perf_event_v7.c"
610
611 /*
612 * Ensure the PMU has sane values out of reset.
613 * This requires SMP to be available, so exists as a separate initcall.
614 */
615 static int __init
616 cpu_pmu_reset(void)
617 {
618 if (cpu_pmu && cpu_pmu->reset)
619 return on_each_cpu(cpu_pmu->reset, NULL, 1);
620 return 0;
621 }
622 arch_initcall(cpu_pmu_reset);
623
624 /*
625 * PMU platform driver and devicetree bindings.
626 */
627 static struct of_device_id armpmu_of_device_ids[] = {
628 {.compatible = "arm,cortex-a9-pmu"},
629 {.compatible = "arm,cortex-a8-pmu"},
630 {.compatible = "arm,arm1136-pmu"},
631 {.compatible = "arm,arm1176-pmu"},
632 {},
633 };
634
635 static struct platform_device_id armpmu_plat_device_ids[] = {
636 {.name = "arm-pmu"},
637 {},
638 };
639
640 static int __devinit armpmu_device_probe(struct platform_device *pdev)
641 {
642 if (!cpu_pmu)
643 return -ENODEV;
644
645 cpu_pmu->plat_device = pdev;
646 return 0;
647 }
648
649 static struct platform_driver armpmu_driver = {
650 .driver = {
651 .name = "arm-pmu",
652 .of_match_table = armpmu_of_device_ids,
653 },
654 .probe = armpmu_device_probe,
655 .id_table = armpmu_plat_device_ids,
656 };
657
658 static int __init register_pmu_driver(void)
659 {
660 return platform_driver_register(&armpmu_driver);
661 }
662 device_initcall(register_pmu_driver);
663
664 static struct pmu_hw_events *armpmu_get_cpu_events(void)
665 {
666 return &__get_cpu_var(cpu_hw_events);
667 }
668
669 static void __init cpu_pmu_init(struct arm_pmu *armpmu)
670 {
671 int cpu;
672 for_each_possible_cpu(cpu) {
673 struct pmu_hw_events *events = &per_cpu(cpu_hw_events, cpu);
674 events->events = per_cpu(hw_events, cpu);
675 events->used_mask = per_cpu(used_mask, cpu);
676 raw_spin_lock_init(&events->pmu_lock);
677 }
678 armpmu->get_hw_events = armpmu_get_cpu_events;
679 armpmu->type = ARM_PMU_DEVICE_CPU;
680 }
681
682 /*
683 * CPU PMU identification and registration.
684 */
685 static int __init
686 init_hw_perf_events(void)
687 {
688 unsigned long cpuid = read_cpuid_id();
689 unsigned long implementor = (cpuid & 0xFF000000) >> 24;
690 unsigned long part_number = (cpuid & 0xFFF0);
691
692 /* ARM Ltd CPUs. */
693 if (0x41 == implementor) {
694 switch (part_number) {
695 case 0xB360: /* ARM1136 */
696 case 0xB560: /* ARM1156 */
697 case 0xB760: /* ARM1176 */
698 cpu_pmu = armv6pmu_init();
699 break;
700 case 0xB020: /* ARM11mpcore */
701 cpu_pmu = armv6mpcore_pmu_init();
702 break;
703 case 0xC080: /* Cortex-A8 */
704 cpu_pmu = armv7_a8_pmu_init();
705 break;
706 case 0xC090: /* Cortex-A9 */
707 cpu_pmu = armv7_a9_pmu_init();
708 break;
709 case 0xC050: /* Cortex-A5 */
710 cpu_pmu = armv7_a5_pmu_init();
711 break;
712 case 0xC0F0: /* Cortex-A15 */
713 cpu_pmu = armv7_a15_pmu_init();
714 break;
715 }
716 /* Intel CPUs [xscale]. */
717 } else if (0x69 == implementor) {
718 part_number = (cpuid >> 13) & 0x7;
719 switch (part_number) {
720 case 1:
721 cpu_pmu = xscale1pmu_init();
722 break;
723 case 2:
724 cpu_pmu = xscale2pmu_init();
725 break;
726 }
727 }
728
729 if (cpu_pmu) {
730 pr_info("enabled with %s PMU driver, %d counters available\n",
731 cpu_pmu->name, cpu_pmu->num_events);
732 cpu_pmu_init(cpu_pmu);
733 armpmu_register(cpu_pmu, "cpu", PERF_TYPE_RAW);
734 } else {
735 pr_info("no hardware support available\n");
736 }
737
738 return 0;
739 }
740 early_initcall(init_hw_perf_events);
741
742 /*
743 * Callchain handling code.
744 */
745
746 /*
747 * The registers we're interested in are at the end of the variable
748 * length saved register structure. The fp points at the end of this
749 * structure so the address of this struct is:
750 * (struct frame_tail *)(xxx->fp)-1
751 *
752 * This code has been adapted from the ARM OProfile support.
753 */
754 struct frame_tail {
755 struct frame_tail __user *fp;
756 unsigned long sp;
757 unsigned long lr;
758 } __attribute__((packed));
759
760 /*
761 * Get the return address for a single stackframe and return a pointer to the
762 * next frame tail.
763 */
764 static struct frame_tail __user *
765 user_backtrace(struct frame_tail __user *tail,
766 struct perf_callchain_entry *entry)
767 {
768 struct frame_tail buftail;
769
770 /* Also check accessibility of one struct frame_tail beyond */
771 if (!access_ok(VERIFY_READ, tail, sizeof(buftail)))
772 return NULL;
773 if (__copy_from_user_inatomic(&buftail, tail, sizeof(buftail)))
774 return NULL;
775
776 perf_callchain_store(entry, buftail.lr);
777
778 /*
779 * Frame pointers should strictly progress back up the stack
780 * (towards higher addresses).
781 */
782 if (tail + 1 >= buftail.fp)
783 return NULL;
784
785 return buftail.fp - 1;
786 }
787
788 void
789 perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
790 {
791 struct frame_tail __user *tail;
792
793
794 tail = (struct frame_tail __user *)regs->ARM_fp - 1;
795
796 while ((entry->nr < PERF_MAX_STACK_DEPTH) &&
797 tail && !((unsigned long)tail & 0x3))
798 tail = user_backtrace(tail, entry);
799 }
800
801 /*
802 * Gets called by walk_stackframe() for every stackframe. This will be called
803 * whist unwinding the stackframe and is like a subroutine return so we use
804 * the PC.
805 */
806 static int
807 callchain_trace(struct stackframe *fr,
808 void *data)
809 {
810 struct perf_callchain_entry *entry = data;
811 perf_callchain_store(entry, fr->pc);
812 return 0;
813 }
814
815 void
816 perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)
817 {
818 struct stackframe fr;
819
820 fr.fp = regs->ARM_fp;
821 fr.sp = regs->ARM_sp;
822 fr.lr = regs->ARM_lr;
823 fr.pc = regs->ARM_pc;
824 walk_stackframe(&fr, callchain_trace, entry);
825 }