1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright(C) 2016 Linaro Limited. All rights reserved.
4  * Author: Mathieu Poirier <mathieu.poirier@linaro.org>
5  */
6 
7 #include <linux/atomic.h>
8 #include <linux/circ_buf.h>
9 #include <linux/coresight.h>
10 #include <linux/perf_event.h>
11 #include <linux/slab.h>
12 #include "coresight-priv.h"
13 #include "coresight-tmc.h"
14 #include "coresight-etm-perf.h"
15 
16 static int tmc_set_etf_buffer(struct coresight_device *csdev,
17 			      struct perf_output_handle *handle);
18 
19 static void __tmc_etb_enable_hw(struct tmc_drvdata *drvdata)
20 {
21 	CS_UNLOCK(drvdata->base);
22 
23 	/* Wait for TMCSReady bit to be set */
24 	tmc_wait_for_tmcready(drvdata);
25 
26 	writel_relaxed(TMC_MODE_CIRCULAR_BUFFER, drvdata->base + TMC_MODE);
27 	writel_relaxed(TMC_FFCR_EN_FMT | TMC_FFCR_EN_TI |
28 		       TMC_FFCR_FON_FLIN | TMC_FFCR_FON_TRIG_EVT |
29 		       TMC_FFCR_TRIGON_TRIGIN,
30 		       drvdata->base + TMC_FFCR);
31 
32 	writel_relaxed(drvdata->trigger_cntr, drvdata->base + TMC_TRG);
33 	tmc_enable_hw(drvdata);
34 
35 	CS_LOCK(drvdata->base);
36 }
37 
38 static int tmc_etb_enable_hw(struct tmc_drvdata *drvdata)
39 {
40 	int rc = coresight_claim_device(drvdata->base);
41 
42 	if (rc)
43 		return rc;
44 
45 	__tmc_etb_enable_hw(drvdata);
46 	return 0;
47 }
48 
49 static void tmc_etb_dump_hw(struct tmc_drvdata *drvdata)
50 {
51 	char *bufp;
52 	u32 read_data, lost;
53 
54 	/* Check if the buffer wrapped around. */
55 	lost = readl_relaxed(drvdata->base + TMC_STS) & TMC_STS_FULL;
56 	bufp = drvdata->buf;
57 	drvdata->len = 0;
58 	while (1) {
59 		read_data = readl_relaxed(drvdata->base + TMC_RRD);
60 		if (read_data == 0xFFFFFFFF)
61 			break;
62 		memcpy(bufp, &read_data, 4);
63 		bufp += 4;
64 		drvdata->len += 4;
65 	}
66 
67 	if (lost)
68 		coresight_insert_barrier_packet(drvdata->buf);
69 	return;
70 }
71 
72 static void __tmc_etb_disable_hw(struct tmc_drvdata *drvdata)
73 {
74 	CS_UNLOCK(drvdata->base);
75 
76 	tmc_flush_and_stop(drvdata);
77 	/*
78 	 * When operating in sysFS mode the content of the buffer needs to be
79 	 * read before the TMC is disabled.
80 	 */
81 	if (drvdata->mode == CS_MODE_SYSFS)
82 		tmc_etb_dump_hw(drvdata);
83 	tmc_disable_hw(drvdata);
84 
85 	CS_LOCK(drvdata->base);
86 }
87 
88 static void tmc_etb_disable_hw(struct tmc_drvdata *drvdata)
89 {
90 	__tmc_etb_disable_hw(drvdata);
91 	coresight_disclaim_device(drvdata->base);
92 }
93 
94 static void __tmc_etf_enable_hw(struct tmc_drvdata *drvdata)
95 {
96 	CS_UNLOCK(drvdata->base);
97 
98 	/* Wait for TMCSReady bit to be set */
99 	tmc_wait_for_tmcready(drvdata);
100 
101 	writel_relaxed(TMC_MODE_HARDWARE_FIFO, drvdata->base + TMC_MODE);
102 	writel_relaxed(TMC_FFCR_EN_FMT | TMC_FFCR_EN_TI,
103 		       drvdata->base + TMC_FFCR);
104 	writel_relaxed(0x0, drvdata->base + TMC_BUFWM);
105 	tmc_enable_hw(drvdata);
106 
107 	CS_LOCK(drvdata->base);
108 }
109 
110 static int tmc_etf_enable_hw(struct tmc_drvdata *drvdata)
111 {
112 	int rc = coresight_claim_device(drvdata->base);
113 
114 	if (rc)
115 		return rc;
116 
117 	__tmc_etf_enable_hw(drvdata);
118 	return 0;
119 }
120 
121 static void tmc_etf_disable_hw(struct tmc_drvdata *drvdata)
122 {
123 	CS_UNLOCK(drvdata->base);
124 
125 	tmc_flush_and_stop(drvdata);
126 	tmc_disable_hw(drvdata);
127 	coresight_disclaim_device_unlocked(drvdata->base);
128 	CS_LOCK(drvdata->base);
129 }
130 
131 /*
132  * Return the available trace data in the buffer from @pos, with
133  * a maximum limit of @len, updating the @bufpp on where to
134  * find it.
135  */
136 ssize_t tmc_etb_get_sysfs_trace(struct tmc_drvdata *drvdata,
137 				loff_t pos, size_t len, char **bufpp)
138 {
139 	ssize_t actual = len;
140 
141 	/* Adjust the len to available size @pos */
142 	if (pos + actual > drvdata->len)
143 		actual = drvdata->len - pos;
144 	if (actual > 0)
145 		*bufpp = drvdata->buf + pos;
146 	return actual;
147 }
148 
149 static int tmc_enable_etf_sink_sysfs(struct coresight_device *csdev)
150 {
151 	int ret = 0;
152 	bool used = false;
153 	char *buf = NULL;
154 	unsigned long flags;
155 	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
156 
157 	/*
158 	 * If we don't have a buffer release the lock and allocate memory.
159 	 * Otherwise keep the lock and move along.
160 	 */
161 	spin_lock_irqsave(&drvdata->spinlock, flags);
162 	if (!drvdata->buf) {
163 		spin_unlock_irqrestore(&drvdata->spinlock, flags);
164 
165 		/* Allocating the memory here while outside of the spinlock */
166 		buf = kzalloc(drvdata->size, GFP_KERNEL);
167 		if (!buf)
168 			return -ENOMEM;
169 
170 		/* Let's try again */
171 		spin_lock_irqsave(&drvdata->spinlock, flags);
172 	}
173 
174 	if (drvdata->reading) {
175 		ret = -EBUSY;
176 		goto out;
177 	}
178 
179 	/*
180 	 * In sysFS mode we can have multiple writers per sink.  Since this
181 	 * sink is already enabled no memory is needed and the HW need not be
182 	 * touched.
183 	 */
184 	if (drvdata->mode == CS_MODE_SYSFS) {
185 		atomic_inc(csdev->refcnt);
186 		goto out;
187 	}
188 
189 	/*
190 	 * If drvdata::buf isn't NULL, memory was allocated for a previous
191 	 * trace run but wasn't read.  If so simply zero-out the memory.
192 	 * Otherwise use the memory allocated above.
193 	 *
194 	 * The memory is freed when users read the buffer using the
195 	 * /dev/xyz.{etf|etb} interface.  See tmc_read_unprepare_etf() for
196 	 * details.
197 	 */
198 	if (drvdata->buf) {
199 		memset(drvdata->buf, 0, drvdata->size);
200 	} else {
201 		used = true;
202 		drvdata->buf = buf;
203 	}
204 
205 	ret = tmc_etb_enable_hw(drvdata);
206 	if (!ret) {
207 		drvdata->mode = CS_MODE_SYSFS;
208 		atomic_inc(csdev->refcnt);
209 	} else {
210 		/* Free up the buffer if we failed to enable */
211 		used = false;
212 	}
213 out:
214 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
215 
216 	/* Free memory outside the spinlock if need be */
217 	if (!used)
218 		kfree(buf);
219 
220 	return ret;
221 }
222 
223 static int tmc_enable_etf_sink_perf(struct coresight_device *csdev, void *data)
224 {
225 	int ret = 0;
226 	pid_t pid;
227 	unsigned long flags;
228 	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
229 	struct perf_output_handle *handle = data;
230 
231 	spin_lock_irqsave(&drvdata->spinlock, flags);
232 	do {
233 		ret = -EINVAL;
234 		if (drvdata->reading)
235 			break;
236 		/*
237 		 * No need to continue if the ETB/ETF is already operated
238 		 * from sysFS.
239 		 */
240 		if (drvdata->mode == CS_MODE_SYSFS) {
241 			ret = -EBUSY;
242 			break;
243 		}
244 
245 		/* Get a handle on the pid of the process to monitor */
246 		pid = task_pid_nr(handle->event->owner);
247 
248 		if (drvdata->pid != -1 && drvdata->pid != pid) {
249 			ret = -EBUSY;
250 			break;
251 		}
252 
253 		ret = tmc_set_etf_buffer(csdev, handle);
254 		if (ret)
255 			break;
256 
257 		/*
258 		 * No HW configuration is needed if the sink is already in
259 		 * use for this session.
260 		 */
261 		if (drvdata->pid == pid) {
262 			atomic_inc(csdev->refcnt);
263 			break;
264 		}
265 
266 		ret  = tmc_etb_enable_hw(drvdata);
267 		if (!ret) {
268 			/* Associate with monitored process. */
269 			drvdata->pid = pid;
270 			drvdata->mode = CS_MODE_PERF;
271 			atomic_inc(csdev->refcnt);
272 		}
273 	} while (0);
274 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
275 
276 	return ret;
277 }
278 
279 static int tmc_enable_etf_sink(struct coresight_device *csdev,
280 			       u32 mode, void *data)
281 {
282 	int ret;
283 
284 	switch (mode) {
285 	case CS_MODE_SYSFS:
286 		ret = tmc_enable_etf_sink_sysfs(csdev);
287 		break;
288 	case CS_MODE_PERF:
289 		ret = tmc_enable_etf_sink_perf(csdev, data);
290 		break;
291 	/* We shouldn't be here */
292 	default:
293 		ret = -EINVAL;
294 		break;
295 	}
296 
297 	if (ret)
298 		return ret;
299 
300 	dev_dbg(&csdev->dev, "TMC-ETB/ETF enabled\n");
301 	return 0;
302 }
303 
304 static int tmc_disable_etf_sink(struct coresight_device *csdev)
305 {
306 	unsigned long flags;
307 	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
308 
309 	spin_lock_irqsave(&drvdata->spinlock, flags);
310 
311 	if (drvdata->reading) {
312 		spin_unlock_irqrestore(&drvdata->spinlock, flags);
313 		return -EBUSY;
314 	}
315 
316 	if (atomic_dec_return(csdev->refcnt)) {
317 		spin_unlock_irqrestore(&drvdata->spinlock, flags);
318 		return -EBUSY;
319 	}
320 
321 	/* Complain if we (somehow) got out of sync */
322 	WARN_ON_ONCE(drvdata->mode == CS_MODE_DISABLED);
323 	tmc_etb_disable_hw(drvdata);
324 	/* Dissociate from monitored process. */
325 	drvdata->pid = -1;
326 	drvdata->mode = CS_MODE_DISABLED;
327 
328 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
329 
330 	dev_dbg(&csdev->dev, "TMC-ETB/ETF disabled\n");
331 	return 0;
332 }
333 
334 static int tmc_enable_etf_link(struct coresight_device *csdev,
335 			       int inport, int outport)
336 {
337 	int ret = 0;
338 	unsigned long flags;
339 	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
340 	bool first_enable = false;
341 
342 	spin_lock_irqsave(&drvdata->spinlock, flags);
343 	if (drvdata->reading) {
344 		spin_unlock_irqrestore(&drvdata->spinlock, flags);
345 		return -EBUSY;
346 	}
347 
348 	if (atomic_read(&csdev->refcnt[0]) == 0) {
349 		ret = tmc_etf_enable_hw(drvdata);
350 		if (!ret) {
351 			drvdata->mode = CS_MODE_SYSFS;
352 			first_enable = true;
353 		}
354 	}
355 	if (!ret)
356 		atomic_inc(&csdev->refcnt[0]);
357 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
358 
359 	if (first_enable)
360 		dev_dbg(&csdev->dev, "TMC-ETF enabled\n");
361 	return ret;
362 }
363 
364 static void tmc_disable_etf_link(struct coresight_device *csdev,
365 				 int inport, int outport)
366 {
367 	unsigned long flags;
368 	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
369 	bool last_disable = false;
370 
371 	spin_lock_irqsave(&drvdata->spinlock, flags);
372 	if (drvdata->reading) {
373 		spin_unlock_irqrestore(&drvdata->spinlock, flags);
374 		return;
375 	}
376 
377 	if (atomic_dec_return(&csdev->refcnt[0]) == 0) {
378 		tmc_etf_disable_hw(drvdata);
379 		drvdata->mode = CS_MODE_DISABLED;
380 		last_disable = true;
381 	}
382 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
383 
384 	if (last_disable)
385 		dev_dbg(&csdev->dev, "TMC-ETF disabled\n");
386 }
387 
388 static void *tmc_alloc_etf_buffer(struct coresight_device *csdev,
389 				  struct perf_event *event, void **pages,
390 				  int nr_pages, bool overwrite)
391 {
392 	int node;
393 	struct cs_buffers *buf;
394 
395 	node = (event->cpu == -1) ? NUMA_NO_NODE : cpu_to_node(event->cpu);
396 
397 	/* Allocate memory structure for interaction with Perf */
398 	buf = kzalloc_node(sizeof(struct cs_buffers), GFP_KERNEL, node);
399 	if (!buf)
400 		return NULL;
401 
402 	buf->snapshot = overwrite;
403 	buf->nr_pages = nr_pages;
404 	buf->data_pages = pages;
405 
406 	return buf;
407 }
408 
409 static void tmc_free_etf_buffer(void *config)
410 {
411 	struct cs_buffers *buf = config;
412 
413 	kfree(buf);
414 }
415 
416 static int tmc_set_etf_buffer(struct coresight_device *csdev,
417 			      struct perf_output_handle *handle)
418 {
419 	int ret = 0;
420 	unsigned long head;
421 	struct cs_buffers *buf = etm_perf_sink_config(handle);
422 
423 	if (!buf)
424 		return -EINVAL;
425 
426 	/* wrap head around to the amount of space we have */
427 	head = handle->head & ((buf->nr_pages << PAGE_SHIFT) - 1);
428 
429 	/* find the page to write to */
430 	buf->cur = head / PAGE_SIZE;
431 
432 	/* and offset within that page */
433 	buf->offset = head % PAGE_SIZE;
434 
435 	local_set(&buf->data_size, 0);
436 
437 	return ret;
438 }
439 
440 static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev,
441 				  struct perf_output_handle *handle,
442 				  void *sink_config)
443 {
444 	bool lost = false;
445 	int i, cur;
446 	const u32 *barrier;
447 	u32 *buf_ptr;
448 	u64 read_ptr, write_ptr;
449 	u32 status;
450 	unsigned long offset, to_read = 0, flags;
451 	struct cs_buffers *buf = sink_config;
452 	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
453 
454 	if (!buf)
455 		return 0;
456 
457 	/* This shouldn't happen */
458 	if (WARN_ON_ONCE(drvdata->mode != CS_MODE_PERF))
459 		return 0;
460 
461 	spin_lock_irqsave(&drvdata->spinlock, flags);
462 
463 	/* Don't do anything if another tracer is using this sink */
464 	if (atomic_read(csdev->refcnt) != 1)
465 		goto out;
466 
467 	CS_UNLOCK(drvdata->base);
468 
469 	tmc_flush_and_stop(drvdata);
470 
471 	read_ptr = tmc_read_rrp(drvdata);
472 	write_ptr = tmc_read_rwp(drvdata);
473 
474 	/*
475 	 * Get a hold of the status register and see if a wrap around
476 	 * has occurred.  If so adjust things accordingly.
477 	 */
478 	status = readl_relaxed(drvdata->base + TMC_STS);
479 	if (status & TMC_STS_FULL) {
480 		lost = true;
481 		to_read = drvdata->size;
482 	} else {
483 		to_read = CIRC_CNT(write_ptr, read_ptr, drvdata->size);
484 	}
485 
486 	/*
487 	 * The TMC RAM buffer may be bigger than the space available in the
488 	 * perf ring buffer (handle->size).  If so advance the RRP so that we
489 	 * get the latest trace data.  In snapshot mode none of that matters
490 	 * since we are expected to clobber stale data in favour of the latest
491 	 * traces.
492 	 */
493 	if (!buf->snapshot && to_read > handle->size) {
494 		u32 mask = tmc_get_memwidth_mask(drvdata);
495 
496 		/*
497 		 * Make sure the new size is aligned in accordance with the
498 		 * requirement explained in function tmc_get_memwidth_mask().
499 		 */
500 		to_read = handle->size & mask;
501 		/* Move the RAM read pointer up */
502 		read_ptr = (write_ptr + drvdata->size) - to_read;
503 		/* Make sure we are still within our limits */
504 		if (read_ptr > (drvdata->size - 1))
505 			read_ptr -= drvdata->size;
506 		/* Tell the HW */
507 		tmc_write_rrp(drvdata, read_ptr);
508 		lost = true;
509 	}
510 
511 	/*
512 	 * Don't set the TRUNCATED flag in snapshot mode because 1) the
513 	 * captured buffer is expected to be truncated and 2) a full buffer
514 	 * prevents the event from being re-enabled by the perf core,
515 	 * resulting in stale data being send to user space.
516 	 */
517 	if (!buf->snapshot && lost)
518 		perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
519 
520 	cur = buf->cur;
521 	offset = buf->offset;
522 	barrier = barrier_pkt;
523 
524 	/* for every byte to read */
525 	for (i = 0; i < to_read; i += 4) {
526 		buf_ptr = buf->data_pages[cur] + offset;
527 		*buf_ptr = readl_relaxed(drvdata->base + TMC_RRD);
528 
529 		if (lost && *barrier) {
530 			*buf_ptr = *barrier;
531 			barrier++;
532 		}
533 
534 		offset += 4;
535 		if (offset >= PAGE_SIZE) {
536 			offset = 0;
537 			cur++;
538 			/* wrap around at the end of the buffer */
539 			cur &= buf->nr_pages - 1;
540 		}
541 	}
542 
543 	/*
544 	 * In snapshot mode we simply increment the head by the number of byte
545 	 * that were written.  User space function  cs_etm_find_snapshot() will
546 	 * figure out how many bytes to get from the AUX buffer based on the
547 	 * position of the head.
548 	 */
549 	if (buf->snapshot)
550 		handle->head += to_read;
551 
552 	CS_LOCK(drvdata->base);
553 out:
554 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
555 
556 	return to_read;
557 }
558 
559 static const struct coresight_ops_sink tmc_etf_sink_ops = {
560 	.enable		= tmc_enable_etf_sink,
561 	.disable	= tmc_disable_etf_sink,
562 	.alloc_buffer	= tmc_alloc_etf_buffer,
563 	.free_buffer	= tmc_free_etf_buffer,
564 	.update_buffer	= tmc_update_etf_buffer,
565 };
566 
567 static const struct coresight_ops_link tmc_etf_link_ops = {
568 	.enable		= tmc_enable_etf_link,
569 	.disable	= tmc_disable_etf_link,
570 };
571 
572 const struct coresight_ops tmc_etb_cs_ops = {
573 	.sink_ops	= &tmc_etf_sink_ops,
574 };
575 
576 const struct coresight_ops tmc_etf_cs_ops = {
577 	.sink_ops	= &tmc_etf_sink_ops,
578 	.link_ops	= &tmc_etf_link_ops,
579 };
580 
581 int tmc_read_prepare_etb(struct tmc_drvdata *drvdata)
582 {
583 	enum tmc_mode mode;
584 	int ret = 0;
585 	unsigned long flags;
586 
587 	/* config types are set a boot time and never change */
588 	if (WARN_ON_ONCE(drvdata->config_type != TMC_CONFIG_TYPE_ETB &&
589 			 drvdata->config_type != TMC_CONFIG_TYPE_ETF))
590 		return -EINVAL;
591 
592 	spin_lock_irqsave(&drvdata->spinlock, flags);
593 
594 	if (drvdata->reading) {
595 		ret = -EBUSY;
596 		goto out;
597 	}
598 
599 	/* Don't interfere if operated from Perf */
600 	if (drvdata->mode == CS_MODE_PERF) {
601 		ret = -EINVAL;
602 		goto out;
603 	}
604 
605 	/* If drvdata::buf is NULL the trace data has been read already */
606 	if (drvdata->buf == NULL) {
607 		ret = -EINVAL;
608 		goto out;
609 	}
610 
611 	/* Disable the TMC if need be */
612 	if (drvdata->mode == CS_MODE_SYSFS) {
613 		/* There is no point in reading a TMC in HW FIFO mode */
614 		mode = readl_relaxed(drvdata->base + TMC_MODE);
615 		if (mode != TMC_MODE_CIRCULAR_BUFFER) {
616 			ret = -EINVAL;
617 			goto out;
618 		}
619 		__tmc_etb_disable_hw(drvdata);
620 	}
621 
622 	drvdata->reading = true;
623 out:
624 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
625 
626 	return ret;
627 }
628 
629 int tmc_read_unprepare_etb(struct tmc_drvdata *drvdata)
630 {
631 	char *buf = NULL;
632 	enum tmc_mode mode;
633 	unsigned long flags;
634 
635 	/* config types are set a boot time and never change */
636 	if (WARN_ON_ONCE(drvdata->config_type != TMC_CONFIG_TYPE_ETB &&
637 			 drvdata->config_type != TMC_CONFIG_TYPE_ETF))
638 		return -EINVAL;
639 
640 	spin_lock_irqsave(&drvdata->spinlock, flags);
641 
642 	/* There is no point in reading a TMC in HW FIFO mode */
643 	mode = readl_relaxed(drvdata->base + TMC_MODE);
644 	if (mode != TMC_MODE_CIRCULAR_BUFFER) {
645 		spin_unlock_irqrestore(&drvdata->spinlock, flags);
646 		return -EINVAL;
647 	}
648 
649 	/* Re-enable the TMC if need be */
650 	if (drvdata->mode == CS_MODE_SYSFS) {
651 		/*
652 		 * The trace run will continue with the same allocated trace
653 		 * buffer. As such zero-out the buffer so that we don't end
654 		 * up with stale data.
655 		 *
656 		 * Since the tracer is still enabled drvdata::buf
657 		 * can't be NULL.
658 		 */
659 		memset(drvdata->buf, 0, drvdata->size);
660 		__tmc_etb_enable_hw(drvdata);
661 	} else {
662 		/*
663 		 * The ETB/ETF is not tracing and the buffer was just read.
664 		 * As such prepare to free the trace buffer.
665 		 */
666 		buf = drvdata->buf;
667 		drvdata->buf = NULL;
668 	}
669 
670 	drvdata->reading = false;
671 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
672 
673 	/*
674 	 * Free allocated memory outside of the spinlock.  There is no need
675 	 * to assert the validity of 'buf' since calling kfree(NULL) is safe.
676 	 */
677 	kfree(buf);
678 
679 	return 0;
680 }
681