1// SPDX-License-Identifier: GPL-2.0
  2#include <sys/mman.h>
  3#include <inttypes.h>
  4#include <asm/bug.h>
  5#include <errno.h>
  6#include <string.h>
  7#include <linux/ring_buffer.h>
  8#include <linux/perf_event.h>
  9#include <perf/mmap.h>
 10#include <perf/event.h>
 11#include <perf/evsel.h>
 12#include <internal/mmap.h>
 13#include <internal/lib.h>
 14#include <linux/kernel.h>
 15#include <linux/math64.h>
 16#include <linux/stringify.h>
 17#include "internal.h"
 18
 19void perf_mmap__init(struct perf_mmap *map, struct perf_mmap *prev,
 20		     bool overwrite, libperf_unmap_cb_t unmap_cb)
 21{
 22	map->fd = -1;
 23	map->overwrite = overwrite;
 24	map->unmap_cb  = unmap_cb;
 25	refcount_set(&map->refcnt, 0);
 26	if (prev)
 27		prev->next = map;
 28}
 29
 30size_t perf_mmap__mmap_len(struct perf_mmap *map)
 31{
 32	return map->mask + 1 + page_size;
 33}
 34
 35int perf_mmap__mmap(struct perf_mmap *map, struct perf_mmap_param *mp,
 36		    int fd, struct perf_cpu cpu)
 37{
 38	map->prev = 0;
 39	map->mask = mp->mask;
 40	map->base = mmap(NULL, perf_mmap__mmap_len(map), mp->prot,
 41			 MAP_SHARED, fd, 0);
 42	if (map->base == MAP_FAILED) {
 43		map->base = NULL;
 44		return -1;
 45	}
 46
 47	map->fd  = fd;
 48	map->cpu = cpu;
 49	return 0;
 50}
 51
 52void perf_mmap__munmap(struct perf_mmap *map)
 53{
 54	if (map && map->base != NULL) {
 55		munmap(map->base, perf_mmap__mmap_len(map));
 56		map->base = NULL;
 57		map->fd = -1;
 58		refcount_set(&map->refcnt, 0);
 59	}
 60	if (map && map->unmap_cb)
 61		map->unmap_cb(map);
 62}
 63
 64void perf_mmap__get(struct perf_mmap *map)
 65{
 66	refcount_inc(&map->refcnt);
 67}
 68
 69void perf_mmap__put(struct perf_mmap *map)
 70{
 71	BUG_ON(map->base && refcount_read(&map->refcnt) == 0);
 72
 73	if (refcount_dec_and_test(&map->refcnt))
 74		perf_mmap__munmap(map);
 75}
 76
 77static inline void perf_mmap__write_tail(struct perf_mmap *md, u64 tail)
 78{
 79	ring_buffer_write_tail(md->base, tail);
 80}
 81
 82u64 perf_mmap__read_head(struct perf_mmap *map)
 83{
 84	return ring_buffer_read_head(map->base);
 85}
 86
 87static bool perf_mmap__empty(struct perf_mmap *map)
 88{
 89	struct perf_event_mmap_page *pc = map->base;
 90
 91	return perf_mmap__read_head(map) == map->prev && !pc->aux_size;
 92}
 93
 94void perf_mmap__consume(struct perf_mmap *map)
 95{
 96	if (!map->overwrite) {
 97		u64 old = map->prev;
 98
 99		perf_mmap__write_tail(map, old);
100	}
101
102	if (refcount_read(&map->refcnt) == 1 && perf_mmap__empty(map))
103		perf_mmap__put(map);
104}
105
106static int overwrite_rb_find_range(void *buf, int mask, u64 *start, u64 *end)
107{
108	struct perf_event_header *pheader;
109	u64 evt_head = *start;
110	int size = mask + 1;
111
112	pr_debug2("%s: buf=%p, start=%"PRIx64"\n", __func__, buf, *start);
113	pheader = (struct perf_event_header *)(buf + (*start & mask));
114	while (true) {
115		if (evt_head - *start >= (unsigned int)size) {
116			pr_debug("Finished reading overwrite ring buffer: rewind\n");
117			if (evt_head - *start > (unsigned int)size)
118				evt_head -= pheader->size;
119			*end = evt_head;
120			return 0;
121		}
122
123		pheader = (struct perf_event_header *)(buf + (evt_head & mask));
124
125		if (pheader->size == 0) {
126			pr_debug("Finished reading overwrite ring buffer: get start\n");
127			*end = evt_head;
128			return 0;
129		}
130
131		evt_head += pheader->size;
132		pr_debug3("move evt_head: %"PRIx64"\n", evt_head);
133	}
134	WARN_ONCE(1, "Shouldn't get here\n");
135	return -1;
136}
137
138/*
139 * Report the start and end of the available data in ringbuffer
140 */
141static int __perf_mmap__read_init(struct perf_mmap *md)
142{
143	u64 head = perf_mmap__read_head(md);
144	u64 old = md->prev;
145	unsigned char *data = md->base + page_size;
146	unsigned long size;
147
148	md->start = md->overwrite ? head : old;
149	md->end = md->overwrite ? old : head;
150
151	if ((md->end - md->start) < md->flush)
152		return -EAGAIN;
153
154	size = md->end - md->start;
155	if (size > (unsigned long)(md->mask) + 1) {
156		if (!md->overwrite) {
157			WARN_ONCE(1, "failed to keep up with mmap data. (warn only once)\n");
158
159			md->prev = head;
160			perf_mmap__consume(md);
161			return -EAGAIN;
162		}
163
164		/*
165		 * Backward ring buffer is full. We still have a chance to read
166		 * most of data from it.
167		 */
168		if (overwrite_rb_find_range(data, md->mask, &md->start, &md->end))
169			return -EINVAL;
170	}
171
172	return 0;
173}
174
175int perf_mmap__read_init(struct perf_mmap *map)
176{
177	/*
178	 * Check if event was unmapped due to a POLLHUP/POLLERR.
179	 */
180	if (!refcount_read(&map->refcnt))
181		return -ENOENT;
182
183	return __perf_mmap__read_init(map);
184}
185
186/*
187 * Mandatory for overwrite mode
188 * The direction of overwrite mode is backward.
189 * The last perf_mmap__read() will set tail to map->core.prev.
190 * Need to correct the map->core.prev to head which is the end of next read.
191 */
192void perf_mmap__read_done(struct perf_mmap *map)
193{
194	/*
195	 * Check if event was unmapped due to a POLLHUP/POLLERR.
196	 */
197	if (!refcount_read(&map->refcnt))
198		return;
199
200	map->prev = perf_mmap__read_head(map);
201}
202
203/* When check_messup is true, 'end' must points to a good entry */
204static union perf_event *perf_mmap__read(struct perf_mmap *map,
205					 u64 *startp, u64 end)
206{
207	unsigned char *data = map->base + page_size;
208	union perf_event *event = NULL;
209	int diff = end - *startp;
210
211	if (diff >= (int)sizeof(event->header)) {
212		size_t size;
213
214		event = (union perf_event *)&data[*startp & map->mask];
215		size = event->header.size;
216
217		if (size < sizeof(event->header) || diff < (int)size)
218			return NULL;
219
220		/*
221		 * Event straddles the mmap boundary -- header should always
222		 * be inside due to u64 alignment of output.
223		 */
224		if ((*startp & map->mask) + size != ((*startp + size) & map->mask)) {
225			unsigned int offset = *startp;
226			unsigned int len = min(sizeof(*event), size), cpy;
227			void *dst = map->event_copy;
228
229			do {
230				cpy = min(map->mask + 1 - (offset & map->mask), len);
231				memcpy(dst, &data[offset & map->mask], cpy);
232				offset += cpy;
233				dst += cpy;
234				len -= cpy;
235			} while (len);
236
237			event = (union perf_event *)map->event_copy;
238		}
239
240		*startp += size;
241	}
242
243	return event;
244}
245
246/*
247 * Read event from ring buffer one by one.
248 * Return one event for each call.
249 *
250 * Usage:
251 * perf_mmap__read_init()
252 * while(event = perf_mmap__read_event()) {
253 *	//process the event
254 *	perf_mmap__consume()
255 * }
256 * perf_mmap__read_done()
257 */
258union perf_event *perf_mmap__read_event(struct perf_mmap *map)
259{
260	union perf_event *event;
261
262	/*
263	 * Check if event was unmapped due to a POLLHUP/POLLERR.
264	 */
265	if (!refcount_read(&map->refcnt))
266		return NULL;
267
268	/* non-overwirte doesn't pause the ringbuffer */
269	if (!map->overwrite)
270		map->end = perf_mmap__read_head(map);
271
272	event = perf_mmap__read(map, &map->start, map->end);
273
274	if (!map->overwrite)
275		map->prev = map->start;
276
277	return event;
278}
279
280#if defined(__i386__) || defined(__x86_64__)
281static u64 read_perf_counter(unsigned int counter)
282{
283	unsigned int low, high;
284
285	asm volatile("rdpmc" : "=a" (low), "=d" (high) : "c" (counter));
286
287	return low | ((u64)high) << 32;
288}
289
290static u64 read_timestamp(void)
291{
292	unsigned int low, high;
293
294	asm volatile("rdtsc" : "=a" (low), "=d" (high));
295
296	return low | ((u64)high) << 32;
297}
298#elif defined(__aarch64__)
299#define read_sysreg(r) ({						\
300	u64 __val;							\
301	asm volatile("mrs %0, " __stringify(r) : "=r" (__val));		\
302	__val;								\
303})
304
305static u64 read_pmccntr(void)
306{
307	return read_sysreg(pmccntr_el0);
308}
309
310#define PMEVCNTR_READ(idx)					\
311	static u64 read_pmevcntr_##idx(void) {			\
312		return read_sysreg(pmevcntr##idx##_el0);	\
313	}
314
315PMEVCNTR_READ(0);
316PMEVCNTR_READ(1);
317PMEVCNTR_READ(2);
318PMEVCNTR_READ(3);
319PMEVCNTR_READ(4);
320PMEVCNTR_READ(5);
321PMEVCNTR_READ(6);
322PMEVCNTR_READ(7);
323PMEVCNTR_READ(8);
324PMEVCNTR_READ(9);
325PMEVCNTR_READ(10);
326PMEVCNTR_READ(11);
327PMEVCNTR_READ(12);
328PMEVCNTR_READ(13);
329PMEVCNTR_READ(14);
330PMEVCNTR_READ(15);
331PMEVCNTR_READ(16);
332PMEVCNTR_READ(17);
333PMEVCNTR_READ(18);
334PMEVCNTR_READ(19);
335PMEVCNTR_READ(20);
336PMEVCNTR_READ(21);
337PMEVCNTR_READ(22);
338PMEVCNTR_READ(23);
339PMEVCNTR_READ(24);
340PMEVCNTR_READ(25);
341PMEVCNTR_READ(26);
342PMEVCNTR_READ(27);
343PMEVCNTR_READ(28);
344PMEVCNTR_READ(29);
345PMEVCNTR_READ(30);
346
347/*
348 * Read a value direct from PMEVCNTR<idx>
349 */
350static u64 read_perf_counter(unsigned int counter)
351{
352	static u64 (* const read_f[])(void) = {
353		read_pmevcntr_0,
354		read_pmevcntr_1,
355		read_pmevcntr_2,
356		read_pmevcntr_3,
357		read_pmevcntr_4,
358		read_pmevcntr_5,
359		read_pmevcntr_6,
360		read_pmevcntr_7,
361		read_pmevcntr_8,
362		read_pmevcntr_9,
363		read_pmevcntr_10,
364		read_pmevcntr_11,
365		read_pmevcntr_13,
366		read_pmevcntr_12,
367		read_pmevcntr_14,
368		read_pmevcntr_15,
369		read_pmevcntr_16,
370		read_pmevcntr_17,
371		read_pmevcntr_18,
372		read_pmevcntr_19,
373		read_pmevcntr_20,
374		read_pmevcntr_21,
375		read_pmevcntr_22,
376		read_pmevcntr_23,
377		read_pmevcntr_24,
378		read_pmevcntr_25,
379		read_pmevcntr_26,
380		read_pmevcntr_27,
381		read_pmevcntr_28,
382		read_pmevcntr_29,
383		read_pmevcntr_30,
384		read_pmccntr
385	};
386
387	if (counter < ARRAY_SIZE(read_f))
388		return (read_f[counter])();
389
390	return 0;
391}
392
393static u64 read_timestamp(void) { return read_sysreg(cntvct_el0); }
394
395#else
396static u64 read_perf_counter(unsigned int counter __maybe_unused) { return 0; }
397static u64 read_timestamp(void) { return 0; }
398#endif
399
400int perf_mmap__read_self(struct perf_mmap *map, struct perf_counts_values *count)
401{
402	struct perf_event_mmap_page *pc = map->base;
403	u32 seq, idx, time_mult = 0, time_shift = 0;
404	u64 cnt, cyc = 0, time_offset = 0, time_cycles = 0, time_mask = ~0ULL;
405
406	if (!pc || !pc->cap_user_rdpmc)
407		return -1;
408
409	do {
410		seq = READ_ONCE(pc->lock);
411		barrier();
412
413		count->ena = READ_ONCE(pc->time_enabled);
414		count->run = READ_ONCE(pc->time_running);
415
416		if (pc->cap_user_time && count->ena != count->run) {
417			cyc = read_timestamp();
418			time_mult = READ_ONCE(pc->time_mult);
419			time_shift = READ_ONCE(pc->time_shift);
420			time_offset = READ_ONCE(pc->time_offset);
421
422			if (pc->cap_user_time_short) {
423				time_cycles = READ_ONCE(pc->time_cycles);
424				time_mask = READ_ONCE(pc->time_mask);
425			}
426		}
427
428		idx = READ_ONCE(pc->index);
429		cnt = READ_ONCE(pc->offset);
430		if (pc->cap_user_rdpmc && idx) {
431			s64 evcnt = read_perf_counter(idx - 1);
432			u16 width = READ_ONCE(pc->pmc_width);
433
434			evcnt <<= 64 - width;
435			evcnt >>= 64 - width;
436			cnt += evcnt;
437		} else
438			return -1;
439
440		barrier();
441	} while (READ_ONCE(pc->lock) != seq);
442
443	if (count->ena != count->run) {
444		u64 delta;
445
446		/* Adjust for cap_usr_time_short, a nop if not */
447		cyc = time_cycles + ((cyc - time_cycles) & time_mask);
448
449		delta = time_offset + mul_u64_u32_shr(cyc, time_mult, time_shift);
450
451		count->ena += delta;
452		if (idx)
453			count->run += delta;
454	}
455
456	count->val = cnt;
457
458	return 0;
459}