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8062382c AS |
1 | /* |
2 | * BTS PMU driver for perf | |
3 | * Copyright (c) 2013-2014, Intel Corporation. | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify it | |
6 | * under the terms and conditions of the GNU General Public License, | |
7 | * version 2, as published by the Free Software Foundation. | |
8 | * | |
9 | * This program is distributed in the hope it will be useful, but WITHOUT | |
10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
12 | * more details. | |
13 | */ | |
14 | ||
15 | #undef DEBUG | |
16 | ||
17 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
18 | ||
19 | #include <linux/bitops.h> | |
20 | #include <linux/types.h> | |
21 | #include <linux/slab.h> | |
22 | #include <linux/debugfs.h> | |
23 | #include <linux/device.h> | |
24 | #include <linux/coredump.h> | |
25 | ||
26 | #include <asm-generic/sizes.h> | |
27 | #include <asm/perf_event.h> | |
28 | ||
29 | #include "perf_event.h" | |
30 | ||
31 | struct bts_ctx { | |
32 | struct perf_output_handle handle; | |
33 | struct debug_store ds_back; | |
34 | int started; | |
35 | }; | |
36 | ||
37 | static DEFINE_PER_CPU(struct bts_ctx, bts_ctx); | |
38 | ||
39 | #define BTS_RECORD_SIZE 24 | |
40 | #define BTS_SAFETY_MARGIN 4080 | |
41 | ||
42 | struct bts_phys { | |
43 | struct page *page; | |
44 | unsigned long size; | |
45 | unsigned long offset; | |
46 | unsigned long displacement; | |
47 | }; | |
48 | ||
49 | struct bts_buffer { | |
50 | size_t real_size; /* multiple of BTS_RECORD_SIZE */ | |
51 | unsigned int nr_pages; | |
52 | unsigned int nr_bufs; | |
53 | unsigned int cur_buf; | |
54 | bool snapshot; | |
55 | local_t data_size; | |
56 | local_t lost; | |
57 | local_t head; | |
58 | unsigned long end; | |
59 | void **data_pages; | |
60 | struct bts_phys buf[0]; | |
61 | }; | |
62 | ||
63 | struct pmu bts_pmu; | |
64 | ||
65 | void intel_pmu_enable_bts(u64 config); | |
66 | void intel_pmu_disable_bts(void); | |
67 | ||
68 | static size_t buf_size(struct page *page) | |
69 | { | |
70 | return 1 << (PAGE_SHIFT + page_private(page)); | |
71 | } | |
72 | ||
73 | static void * | |
74 | bts_buffer_setup_aux(int cpu, void **pages, int nr_pages, bool overwrite) | |
75 | { | |
76 | struct bts_buffer *buf; | |
77 | struct page *page; | |
78 | int node = (cpu == -1) ? cpu : cpu_to_node(cpu); | |
79 | unsigned long offset; | |
80 | size_t size = nr_pages << PAGE_SHIFT; | |
81 | int pg, nbuf, pad; | |
82 | ||
83 | /* count all the high order buffers */ | |
84 | for (pg = 0, nbuf = 0; pg < nr_pages;) { | |
85 | page = virt_to_page(pages[pg]); | |
86 | if (WARN_ON_ONCE(!PagePrivate(page) && nr_pages > 1)) | |
87 | return NULL; | |
88 | pg += 1 << page_private(page); | |
89 | nbuf++; | |
90 | } | |
91 | ||
92 | /* | |
93 | * to avoid interrupts in overwrite mode, only allow one physical | |
94 | */ | |
95 | if (overwrite && nbuf > 1) | |
96 | return NULL; | |
97 | ||
98 | buf = kzalloc_node(offsetof(struct bts_buffer, buf[nbuf]), GFP_KERNEL, node); | |
99 | if (!buf) | |
100 | return NULL; | |
101 | ||
102 | buf->nr_pages = nr_pages; | |
103 | buf->nr_bufs = nbuf; | |
104 | buf->snapshot = overwrite; | |
105 | buf->data_pages = pages; | |
106 | buf->real_size = size - size % BTS_RECORD_SIZE; | |
107 | ||
108 | for (pg = 0, nbuf = 0, offset = 0, pad = 0; nbuf < buf->nr_bufs; nbuf++) { | |
109 | unsigned int __nr_pages; | |
110 | ||
111 | page = virt_to_page(pages[pg]); | |
112 | __nr_pages = PagePrivate(page) ? 1 << page_private(page) : 1; | |
113 | buf->buf[nbuf].page = page; | |
114 | buf->buf[nbuf].offset = offset; | |
115 | buf->buf[nbuf].displacement = (pad ? BTS_RECORD_SIZE - pad : 0); | |
116 | buf->buf[nbuf].size = buf_size(page) - buf->buf[nbuf].displacement; | |
117 | pad = buf->buf[nbuf].size % BTS_RECORD_SIZE; | |
118 | buf->buf[nbuf].size -= pad; | |
119 | ||
120 | pg += __nr_pages; | |
121 | offset += __nr_pages << PAGE_SHIFT; | |
122 | } | |
123 | ||
124 | return buf; | |
125 | } | |
126 | ||
127 | static void bts_buffer_free_aux(void *data) | |
128 | { | |
129 | kfree(data); | |
130 | } | |
131 | ||
132 | static unsigned long bts_buffer_offset(struct bts_buffer *buf, unsigned int idx) | |
133 | { | |
134 | return buf->buf[idx].offset + buf->buf[idx].displacement; | |
135 | } | |
136 | ||
137 | static void | |
138 | bts_config_buffer(struct bts_buffer *buf) | |
139 | { | |
140 | int cpu = raw_smp_processor_id(); | |
141 | struct debug_store *ds = per_cpu(cpu_hw_events, cpu).ds; | |
142 | struct bts_phys *phys = &buf->buf[buf->cur_buf]; | |
143 | unsigned long index, thresh = 0, end = phys->size; | |
144 | struct page *page = phys->page; | |
145 | ||
146 | index = local_read(&buf->head); | |
147 | ||
148 | if (!buf->snapshot) { | |
149 | if (buf->end < phys->offset + buf_size(page)) | |
150 | end = buf->end - phys->offset - phys->displacement; | |
151 | ||
152 | index -= phys->offset + phys->displacement; | |
153 | ||
154 | if (end - index > BTS_SAFETY_MARGIN) | |
155 | thresh = end - BTS_SAFETY_MARGIN; | |
156 | else if (end - index > BTS_RECORD_SIZE) | |
157 | thresh = end - BTS_RECORD_SIZE; | |
158 | else | |
159 | thresh = end; | |
160 | } | |
161 | ||
162 | ds->bts_buffer_base = (u64)page_address(page) + phys->displacement; | |
163 | ds->bts_index = ds->bts_buffer_base + index; | |
164 | ds->bts_absolute_maximum = ds->bts_buffer_base + end; | |
165 | ds->bts_interrupt_threshold = !buf->snapshot | |
166 | ? ds->bts_buffer_base + thresh | |
167 | : ds->bts_absolute_maximum + BTS_RECORD_SIZE; | |
168 | } | |
169 | ||
170 | static void bts_buffer_pad_out(struct bts_phys *phys, unsigned long head) | |
171 | { | |
172 | unsigned long index = head - phys->offset; | |
173 | ||
174 | memset(page_address(phys->page) + index, 0, phys->size - index); | |
175 | } | |
176 | ||
177 | static bool bts_buffer_is_full(struct bts_buffer *buf, struct bts_ctx *bts) | |
178 | { | |
179 | if (buf->snapshot) | |
180 | return false; | |
181 | ||
182 | if (local_read(&buf->data_size) >= bts->handle.size || | |
183 | bts->handle.size - local_read(&buf->data_size) < BTS_RECORD_SIZE) | |
184 | return true; | |
185 | ||
186 | return false; | |
187 | } | |
188 | ||
189 | static void bts_update(struct bts_ctx *bts) | |
190 | { | |
191 | int cpu = raw_smp_processor_id(); | |
192 | struct debug_store *ds = per_cpu(cpu_hw_events, cpu).ds; | |
193 | struct bts_buffer *buf = perf_get_aux(&bts->handle); | |
194 | unsigned long index = ds->bts_index - ds->bts_buffer_base, old, head; | |
195 | ||
196 | if (!buf) | |
197 | return; | |
198 | ||
199 | head = index + bts_buffer_offset(buf, buf->cur_buf); | |
200 | old = local_xchg(&buf->head, head); | |
201 | ||
202 | if (!buf->snapshot) { | |
203 | if (old == head) | |
204 | return; | |
205 | ||
206 | if (ds->bts_index >= ds->bts_absolute_maximum) | |
207 | local_inc(&buf->lost); | |
208 | ||
209 | /* | |
210 | * old and head are always in the same physical buffer, so we | |
211 | * can subtract them to get the data size. | |
212 | */ | |
213 | local_add(head - old, &buf->data_size); | |
214 | } else { | |
215 | local_set(&buf->data_size, head); | |
216 | } | |
217 | } | |
218 | ||
219 | static void __bts_event_start(struct perf_event *event) | |
220 | { | |
221 | struct bts_ctx *bts = this_cpu_ptr(&bts_ctx); | |
222 | struct bts_buffer *buf = perf_get_aux(&bts->handle); | |
223 | u64 config = 0; | |
224 | ||
225 | if (!buf || bts_buffer_is_full(buf, bts)) | |
226 | return; | |
227 | ||
228 | event->hw.state = 0; | |
229 | ||
230 | if (!buf->snapshot) | |
231 | config |= ARCH_PERFMON_EVENTSEL_INT; | |
232 | if (!event->attr.exclude_kernel) | |
233 | config |= ARCH_PERFMON_EVENTSEL_OS; | |
234 | if (!event->attr.exclude_user) | |
235 | config |= ARCH_PERFMON_EVENTSEL_USR; | |
236 | ||
237 | bts_config_buffer(buf); | |
238 | ||
239 | /* | |
240 | * local barrier to make sure that ds configuration made it | |
241 | * before we enable BTS | |
242 | */ | |
243 | wmb(); | |
244 | ||
245 | intel_pmu_enable_bts(config); | |
246 | } | |
247 | ||
248 | static void bts_event_start(struct perf_event *event, int flags) | |
249 | { | |
250 | struct bts_ctx *bts = this_cpu_ptr(&bts_ctx); | |
251 | ||
252 | __bts_event_start(event); | |
253 | ||
254 | /* PMI handler: this counter is running and likely generating PMIs */ | |
255 | ACCESS_ONCE(bts->started) = 1; | |
256 | } | |
257 | ||
258 | static void __bts_event_stop(struct perf_event *event) | |
259 | { | |
260 | /* | |
261 | * No extra synchronization is mandated by the documentation to have | |
262 | * BTS data stores globally visible. | |
263 | */ | |
264 | intel_pmu_disable_bts(); | |
265 | ||
266 | if (event->hw.state & PERF_HES_STOPPED) | |
267 | return; | |
268 | ||
269 | ACCESS_ONCE(event->hw.state) |= PERF_HES_STOPPED; | |
270 | } | |
271 | ||
272 | static void bts_event_stop(struct perf_event *event, int flags) | |
273 | { | |
274 | struct bts_ctx *bts = this_cpu_ptr(&bts_ctx); | |
275 | ||
276 | /* PMI handler: don't restart this counter */ | |
277 | ACCESS_ONCE(bts->started) = 0; | |
278 | ||
279 | __bts_event_stop(event); | |
280 | ||
281 | if (flags & PERF_EF_UPDATE) | |
282 | bts_update(bts); | |
283 | } | |
284 | ||
285 | void intel_bts_enable_local(void) | |
286 | { | |
287 | struct bts_ctx *bts = this_cpu_ptr(&bts_ctx); | |
288 | ||
289 | if (bts->handle.event && bts->started) | |
290 | __bts_event_start(bts->handle.event); | |
291 | } | |
292 | ||
293 | void intel_bts_disable_local(void) | |
294 | { | |
295 | struct bts_ctx *bts = this_cpu_ptr(&bts_ctx); | |
296 | ||
297 | if (bts->handle.event) | |
298 | __bts_event_stop(bts->handle.event); | |
299 | } | |
300 | ||
301 | static int | |
302 | bts_buffer_reset(struct bts_buffer *buf, struct perf_output_handle *handle) | |
303 | { | |
304 | unsigned long head, space, next_space, pad, gap, skip, wakeup; | |
305 | unsigned int next_buf; | |
306 | struct bts_phys *phys, *next_phys; | |
307 | int ret; | |
308 | ||
309 | if (buf->snapshot) | |
310 | return 0; | |
311 | ||
312 | head = handle->head & ((buf->nr_pages << PAGE_SHIFT) - 1); | |
313 | if (WARN_ON_ONCE(head != local_read(&buf->head))) | |
314 | return -EINVAL; | |
315 | ||
316 | phys = &buf->buf[buf->cur_buf]; | |
317 | space = phys->offset + phys->displacement + phys->size - head; | |
318 | pad = space; | |
319 | if (space > handle->size) { | |
320 | space = handle->size; | |
321 | space -= space % BTS_RECORD_SIZE; | |
322 | } | |
323 | if (space <= BTS_SAFETY_MARGIN) { | |
324 | /* See if next phys buffer has more space */ | |
325 | next_buf = buf->cur_buf + 1; | |
326 | if (next_buf >= buf->nr_bufs) | |
327 | next_buf = 0; | |
328 | next_phys = &buf->buf[next_buf]; | |
329 | gap = buf_size(phys->page) - phys->displacement - phys->size + | |
330 | next_phys->displacement; | |
331 | skip = pad + gap; | |
332 | if (handle->size >= skip) { | |
333 | next_space = next_phys->size; | |
334 | if (next_space + skip > handle->size) { | |
335 | next_space = handle->size - skip; | |
336 | next_space -= next_space % BTS_RECORD_SIZE; | |
337 | } | |
338 | if (next_space > space || !space) { | |
339 | if (pad) | |
340 | bts_buffer_pad_out(phys, head); | |
341 | ret = perf_aux_output_skip(handle, skip); | |
342 | if (ret) | |
343 | return ret; | |
344 | /* Advance to next phys buffer */ | |
345 | phys = next_phys; | |
346 | space = next_space; | |
347 | head = phys->offset + phys->displacement; | |
348 | /* | |
349 | * After this, cur_buf and head won't match ds | |
350 | * anymore, so we must not be racing with | |
351 | * bts_update(). | |
352 | */ | |
353 | buf->cur_buf = next_buf; | |
354 | local_set(&buf->head, head); | |
355 | } | |
356 | } | |
357 | } | |
358 | ||
359 | /* Don't go far beyond wakeup watermark */ | |
360 | wakeup = BTS_SAFETY_MARGIN + BTS_RECORD_SIZE + handle->wakeup - | |
361 | handle->head; | |
362 | if (space > wakeup) { | |
363 | space = wakeup; | |
364 | space -= space % BTS_RECORD_SIZE; | |
365 | } | |
366 | ||
367 | buf->end = head + space; | |
368 | ||
369 | /* | |
370 | * If we have no space, the lost notification would have been sent when | |
371 | * we hit absolute_maximum - see bts_update() | |
372 | */ | |
373 | if (!space) | |
374 | return -ENOSPC; | |
375 | ||
376 | return 0; | |
377 | } | |
378 | ||
379 | int intel_bts_interrupt(void) | |
380 | { | |
381 | struct bts_ctx *bts = this_cpu_ptr(&bts_ctx); | |
382 | struct perf_event *event = bts->handle.event; | |
383 | struct bts_buffer *buf; | |
384 | s64 old_head; | |
385 | int err; | |
386 | ||
387 | if (!event || !bts->started) | |
388 | return 0; | |
389 | ||
390 | buf = perf_get_aux(&bts->handle); | |
391 | /* | |
392 | * Skip snapshot counters: they don't use the interrupt, but | |
393 | * there's no other way of telling, because the pointer will | |
394 | * keep moving | |
395 | */ | |
396 | if (!buf || buf->snapshot) | |
397 | return 0; | |
398 | ||
399 | old_head = local_read(&buf->head); | |
400 | bts_update(bts); | |
401 | ||
402 | /* no new data */ | |
403 | if (old_head == local_read(&buf->head)) | |
404 | return 0; | |
405 | ||
406 | perf_aux_output_end(&bts->handle, local_xchg(&buf->data_size, 0), | |
407 | !!local_xchg(&buf->lost, 0)); | |
408 | ||
409 | buf = perf_aux_output_begin(&bts->handle, event); | |
410 | if (!buf) | |
411 | return 1; | |
412 | ||
413 | err = bts_buffer_reset(buf, &bts->handle); | |
414 | if (err) | |
415 | perf_aux_output_end(&bts->handle, 0, false); | |
416 | ||
417 | return 1; | |
418 | } | |
419 | ||
420 | static void bts_event_del(struct perf_event *event, int mode) | |
421 | { | |
422 | struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); | |
423 | struct bts_ctx *bts = this_cpu_ptr(&bts_ctx); | |
424 | struct bts_buffer *buf = perf_get_aux(&bts->handle); | |
425 | ||
426 | bts_event_stop(event, PERF_EF_UPDATE); | |
427 | ||
428 | if (buf) { | |
429 | if (buf->snapshot) | |
430 | bts->handle.head = | |
431 | local_xchg(&buf->data_size, | |
432 | buf->nr_pages << PAGE_SHIFT); | |
433 | perf_aux_output_end(&bts->handle, local_xchg(&buf->data_size, 0), | |
434 | !!local_xchg(&buf->lost, 0)); | |
435 | } | |
436 | ||
437 | cpuc->ds->bts_index = bts->ds_back.bts_buffer_base; | |
438 | cpuc->ds->bts_buffer_base = bts->ds_back.bts_buffer_base; | |
439 | cpuc->ds->bts_absolute_maximum = bts->ds_back.bts_absolute_maximum; | |
440 | cpuc->ds->bts_interrupt_threshold = bts->ds_back.bts_interrupt_threshold; | |
441 | } | |
442 | ||
443 | static int bts_event_add(struct perf_event *event, int mode) | |
444 | { | |
445 | struct bts_buffer *buf; | |
446 | struct bts_ctx *bts = this_cpu_ptr(&bts_ctx); | |
447 | struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); | |
448 | struct hw_perf_event *hwc = &event->hw; | |
449 | int ret = -EBUSY; | |
450 | ||
451 | event->hw.state = PERF_HES_STOPPED; | |
452 | ||
453 | if (test_bit(INTEL_PMC_IDX_FIXED_BTS, cpuc->active_mask)) | |
454 | return -EBUSY; | |
455 | ||
456 | if (bts->handle.event) | |
457 | return -EBUSY; | |
458 | ||
459 | buf = perf_aux_output_begin(&bts->handle, event); | |
460 | if (!buf) | |
461 | return -EINVAL; | |
462 | ||
463 | ret = bts_buffer_reset(buf, &bts->handle); | |
464 | if (ret) { | |
465 | perf_aux_output_end(&bts->handle, 0, false); | |
466 | return ret; | |
467 | } | |
468 | ||
469 | bts->ds_back.bts_buffer_base = cpuc->ds->bts_buffer_base; | |
470 | bts->ds_back.bts_absolute_maximum = cpuc->ds->bts_absolute_maximum; | |
471 | bts->ds_back.bts_interrupt_threshold = cpuc->ds->bts_interrupt_threshold; | |
472 | ||
473 | if (mode & PERF_EF_START) { | |
474 | bts_event_start(event, 0); | |
475 | if (hwc->state & PERF_HES_STOPPED) { | |
476 | bts_event_del(event, 0); | |
477 | return -EBUSY; | |
478 | } | |
479 | } | |
480 | ||
481 | return 0; | |
482 | } | |
483 | ||
484 | static void bts_event_destroy(struct perf_event *event) | |
485 | { | |
486 | x86_del_exclusive(x86_lbr_exclusive_bts); | |
487 | } | |
488 | ||
489 | static int bts_event_init(struct perf_event *event) | |
490 | { | |
491 | if (event->attr.type != bts_pmu.type) | |
492 | return -ENOENT; | |
493 | ||
494 | if (x86_add_exclusive(x86_lbr_exclusive_bts)) | |
495 | return -EBUSY; | |
496 | ||
497 | event->destroy = bts_event_destroy; | |
498 | ||
499 | return 0; | |
500 | } | |
501 | ||
502 | static void bts_event_read(struct perf_event *event) | |
503 | { | |
504 | } | |
505 | ||
506 | static __init int bts_init(void) | |
507 | { | |
508 | if (!boot_cpu_has(X86_FEATURE_DTES64) || !x86_pmu.bts) | |
509 | return -ENODEV; | |
510 | ||
511 | bts_pmu.capabilities = PERF_PMU_CAP_AUX_NO_SG | PERF_PMU_CAP_ITRACE; | |
512 | bts_pmu.task_ctx_nr = perf_sw_context; | |
513 | bts_pmu.event_init = bts_event_init; | |
514 | bts_pmu.add = bts_event_add; | |
515 | bts_pmu.del = bts_event_del; | |
516 | bts_pmu.start = bts_event_start; | |
517 | bts_pmu.stop = bts_event_stop; | |
518 | bts_pmu.read = bts_event_read; | |
519 | bts_pmu.setup_aux = bts_buffer_setup_aux; | |
520 | bts_pmu.free_aux = bts_buffer_free_aux; | |
521 | ||
522 | return perf_pmu_register(&bts_pmu, "intel_bts", -1); | |
523 | } | |
524 | ||
525 | module_init(bts_init); |