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 /* Assume fields were zero initialized. */
23 map->fd = -1;
24 map->overwrite = overwrite;
25 map->unmap_cb = unmap_cb;
26 refcount_set(r: &map->refcnt, n: 0);
27 if (prev)
28 prev->next = map;
29}
30
31size_t perf_mmap__mmap_len(struct perf_mmap *map)
32{
33 return map->mask + 1 + page_size;
34}
35
36int perf_mmap__mmap(struct perf_mmap *map, struct perf_mmap_param *mp,
37 int fd, struct perf_cpu cpu)
38{
39 map->prev = 0;
40 map->mask = mp->mask;
41 map->base = mmap(NULL, perf_mmap__mmap_len(map), mp->prot,
42 MAP_SHARED, fd, 0);
43 if (map->base == MAP_FAILED) {
44 map->base = NULL;
45 return -1;
46 }
47
48 map->fd = fd;
49 map->cpu = cpu;
50 return 0;
51}
52
53void perf_mmap__munmap(struct perf_mmap *map)
54{
55 if (!map)
56 return;
57
58 zfree(&map->event_copy);
59 map->event_copy_sz = 0;
60 if (map->base) {
61 munmap(map->base, perf_mmap__mmap_len(map));
62 map->base = NULL;
63 map->fd = -1;
64 refcount_set(r: &map->refcnt, n: 0);
65 }
66 if (map->unmap_cb)
67 map->unmap_cb(map);
68}
69
70void perf_mmap__get(struct perf_mmap *map)
71{
72 refcount_inc(r: &map->refcnt);
73}
74
75void perf_mmap__put(struct perf_mmap *map)
76{
77 BUG_ON(map->base && refcount_read(&map->refcnt) == 0);
78
79 if (refcount_dec_and_test(r: &map->refcnt))
80 perf_mmap__munmap(map);
81}
82
83static inline void perf_mmap__write_tail(struct perf_mmap *md, u64 tail)
84{
85 ring_buffer_write_tail(md->base, tail);
86}
87
88u64 perf_mmap__read_head(struct perf_mmap *map)
89{
90 return ring_buffer_read_head(map->base);
91}
92
93static bool perf_mmap__empty(struct perf_mmap *map)
94{
95 struct perf_event_mmap_page *pc = map->base;
96
97 return perf_mmap__read_head(map) == map->prev && !pc->aux_size;
98}
99
100void perf_mmap__consume(struct perf_mmap *map)
101{
102 if (!map->overwrite) {
103 u64 old = map->prev;
104
105 perf_mmap__write_tail(md: map, tail: old);
106 }
107
108 if (refcount_read(r: &map->refcnt) == 1 && perf_mmap__empty(map))
109 perf_mmap__put(map);
110}
111
112static int overwrite_rb_find_range(void *buf, int mask, u64 *start, u64 *end)
113{
114 struct perf_event_header *pheader;
115 u64 evt_head = *start;
116 int size = mask + 1;
117
118 pr_debug2("%s: buf=%p, start=%"PRIx64"\n", __func__, buf, *start);
119 pheader = (struct perf_event_header *)(buf + (*start & mask));
120 while (true) {
121 if (evt_head - *start >= (unsigned int)size) {
122 pr_debug("Finished reading overwrite ring buffer: rewind\n");
123 if (evt_head - *start > (unsigned int)size)
124 evt_head -= pheader->size;
125 *end = evt_head;
126 return 0;
127 }
128
129 pheader = (struct perf_event_header *)(buf + (evt_head & mask));
130
131 if (pheader->size == 0) {
132 pr_debug("Finished reading overwrite ring buffer: get start\n");
133 *end = evt_head;
134 return 0;
135 }
136
137 evt_head += pheader->size;
138 pr_debug3("move evt_head: %"PRIx64"\n", evt_head);
139 }
140 WARN_ONCE(1, "Shouldn't get here\n");
141 return -1;
142}
143
144/*
145 * Report the start and end of the available data in ringbuffer
146 */
147static int __perf_mmap__read_init(struct perf_mmap *md)
148{
149 u64 head = perf_mmap__read_head(map: md);
150 u64 old = md->prev;
151 unsigned char *data = md->base + page_size;
152 unsigned long size;
153
154 md->start = md->overwrite ? head : old;
155 md->end = md->overwrite ? old : head;
156
157 if ((md->end - md->start) < md->flush)
158 return -EAGAIN;
159
160 size = md->end - md->start;
161 if (size > (unsigned long)(md->mask) + 1) {
162 if (!md->overwrite) {
163 WARN_ONCE(1, "failed to keep up with mmap data. (warn only once)\n");
164
165 md->prev = head;
166 perf_mmap__consume(map: md);
167 return -EAGAIN;
168 }
169
170 /*
171 * Backward ring buffer is full. We still have a chance to read
172 * most of data from it.
173 */
174 if (overwrite_rb_find_range(buf: data, mask: md->mask, start: &md->start, end: &md->end))
175 return -EINVAL;
176 }
177
178 return 0;
179}
180
181int perf_mmap__read_init(struct perf_mmap *map)
182{
183 /*
184 * Check if event was unmapped due to a POLLHUP/POLLERR.
185 */
186 if (!refcount_read(r: &map->refcnt))
187 return -ENOENT;
188
189 return __perf_mmap__read_init(md: map);
190}
191
192/*
193 * Mandatory for overwrite mode
194 * The direction of overwrite mode is backward.
195 * The last perf_mmap__read() will set tail to map->core.prev.
196 * Need to correct the map->core.prev to head which is the end of next read.
197 */
198void perf_mmap__read_done(struct perf_mmap *map)
199{
200 /*
201 * Check if event was unmapped due to a POLLHUP/POLLERR.
202 */
203 if (!refcount_read(r: &map->refcnt))
204 return;
205
206 map->prev = perf_mmap__read_head(map);
207}
208
209/* When check_messup is true, 'end' must points to a good entry */
210static union perf_event *perf_mmap__read(struct perf_mmap *map,
211 u64 *startp, u64 end)
212{
213 unsigned char *data = map->base + page_size;
214 union perf_event *event = NULL;
215 int diff = end - *startp;
216
217 if (diff >= (int)sizeof(event->header)) {
218 size_t size;
219
220 event = (union perf_event *)&data[*startp & map->mask];
221 size = event->header.size;
222
223 if (size < sizeof(event->header) || diff < (int)size)
224 return NULL;
225
226 /*
227 * Event straddles the mmap boundary -- header should always
228 * be inside due to u64 alignment of output.
229 */
230 if ((*startp & map->mask) + size != ((*startp + size) & map->mask)) {
231 unsigned int offset = *startp;
232 unsigned int len = size, cpy;
233 void *dst = map->event_copy;
234
235 if (size > map->event_copy_sz) {
236 dst = realloc(map->event_copy, size);
237 if (!dst)
238 return NULL;
239 map->event_copy = dst;
240 map->event_copy_sz = size;
241 }
242
243 do {
244 cpy = min(map->mask + 1 - (offset & map->mask), len);
245 memcpy(dst, &data[offset & map->mask], cpy);
246 offset += cpy;
247 dst += cpy;
248 len -= cpy;
249 } while (len);
250
251 event = (union perf_event *)map->event_copy;
252 }
253
254 *startp += size;
255 }
256
257 return event;
258}
259
260/*
261 * Read event from ring buffer one by one.
262 * Return one event for each call.
263 *
264 * Usage:
265 * perf_mmap__read_init()
266 * while(event = perf_mmap__read_event()) {
267 * //process the event
268 * perf_mmap__consume()
269 * }
270 * perf_mmap__read_done()
271 */
272union perf_event *perf_mmap__read_event(struct perf_mmap *map)
273{
274 union perf_event *event;
275
276 /*
277 * Check if event was unmapped due to a POLLHUP/POLLERR.
278 */
279 if (!refcount_read(r: &map->refcnt))
280 return NULL;
281
282 /* non-overwrite doesn't pause the ringbuffer */
283 if (!map->overwrite)
284 map->end = perf_mmap__read_head(map);
285
286 event = perf_mmap__read(map, startp: &map->start, end: map->end);
287
288 if (!map->overwrite)
289 map->prev = map->start;
290
291 return event;
292}
293
294#if defined(__i386__) || defined(__x86_64__)
295static u64 read_perf_counter(unsigned int counter)
296{
297 unsigned int low, high;
298
299 asm volatile("rdpmc" : "=a" (low), "=d" (high) : "c" (counter));
300
301 return low | ((u64)high) << 32;
302}
303
304static u64 read_timestamp(void)
305{
306 unsigned int low, high;
307
308 asm volatile("rdtsc" : "=a" (low), "=d" (high));
309
310 return low | ((u64)high) << 32;
311}
312#elif defined(__aarch64__)
313#define read_sysreg(r) ({ \
314 u64 __val; \
315 asm volatile("mrs %0, " __stringify(r) : "=r" (__val)); \
316 __val; \
317})
318
319static u64 read_pmccntr(void)
320{
321 return read_sysreg(pmccntr_el0);
322}
323
324#define PMEVCNTR_READ(idx) \
325 static u64 read_pmevcntr_##idx(void) { \
326 return read_sysreg(pmevcntr##idx##_el0); \
327 }
328
329PMEVCNTR_READ(0);
330PMEVCNTR_READ(1);
331PMEVCNTR_READ(2);
332PMEVCNTR_READ(3);
333PMEVCNTR_READ(4);
334PMEVCNTR_READ(5);
335PMEVCNTR_READ(6);
336PMEVCNTR_READ(7);
337PMEVCNTR_READ(8);
338PMEVCNTR_READ(9);
339PMEVCNTR_READ(10);
340PMEVCNTR_READ(11);
341PMEVCNTR_READ(12);
342PMEVCNTR_READ(13);
343PMEVCNTR_READ(14);
344PMEVCNTR_READ(15);
345PMEVCNTR_READ(16);
346PMEVCNTR_READ(17);
347PMEVCNTR_READ(18);
348PMEVCNTR_READ(19);
349PMEVCNTR_READ(20);
350PMEVCNTR_READ(21);
351PMEVCNTR_READ(22);
352PMEVCNTR_READ(23);
353PMEVCNTR_READ(24);
354PMEVCNTR_READ(25);
355PMEVCNTR_READ(26);
356PMEVCNTR_READ(27);
357PMEVCNTR_READ(28);
358PMEVCNTR_READ(29);
359PMEVCNTR_READ(30);
360
361/*
362 * Read a value direct from PMEVCNTR<idx>
363 */
364static u64 read_perf_counter(unsigned int counter)
365{
366 static u64 (* const read_f[])(void) = {
367 read_pmevcntr_0,
368 read_pmevcntr_1,
369 read_pmevcntr_2,
370 read_pmevcntr_3,
371 read_pmevcntr_4,
372 read_pmevcntr_5,
373 read_pmevcntr_6,
374 read_pmevcntr_7,
375 read_pmevcntr_8,
376 read_pmevcntr_9,
377 read_pmevcntr_10,
378 read_pmevcntr_11,
379 read_pmevcntr_13,
380 read_pmevcntr_12,
381 read_pmevcntr_14,
382 read_pmevcntr_15,
383 read_pmevcntr_16,
384 read_pmevcntr_17,
385 read_pmevcntr_18,
386 read_pmevcntr_19,
387 read_pmevcntr_20,
388 read_pmevcntr_21,
389 read_pmevcntr_22,
390 read_pmevcntr_23,
391 read_pmevcntr_24,
392 read_pmevcntr_25,
393 read_pmevcntr_26,
394 read_pmevcntr_27,
395 read_pmevcntr_28,
396 read_pmevcntr_29,
397 read_pmevcntr_30,
398 read_pmccntr
399 };
400
401 if (counter < ARRAY_SIZE(read_f))
402 return (read_f[counter])();
403
404 return 0;
405}
406
407static u64 read_timestamp(void) { return read_sysreg(cntvct_el0); }
408
409/* __riscv_xlen contains the witdh of the native base integer, here 64-bit */
410#elif defined(__riscv) && __riscv_xlen == 64
411
412/* TODO: implement rv32 support */
413
414#define CSR_CYCLE 0xc00
415#define CSR_TIME 0xc01
416
417#define csr_read(csr) \
418({ \
419 register unsigned long __v; \
420 __asm__ __volatile__ ("csrr %0, %1" \
421 : "=r" (__v) \
422 : "i" (csr) : ); \
423 __v; \
424})
425
426static unsigned long csr_read_num(int csr_num)
427{
428#define switchcase_csr_read(__csr_num, __val) {\
429 case __csr_num: \
430 __val = csr_read(__csr_num); \
431 break; }
432#define switchcase_csr_read_2(__csr_num, __val) {\
433 switchcase_csr_read(__csr_num + 0, __val) \
434 switchcase_csr_read(__csr_num + 1, __val)}
435#define switchcase_csr_read_4(__csr_num, __val) {\
436 switchcase_csr_read_2(__csr_num + 0, __val) \
437 switchcase_csr_read_2(__csr_num + 2, __val)}
438#define switchcase_csr_read_8(__csr_num, __val) {\
439 switchcase_csr_read_4(__csr_num + 0, __val) \
440 switchcase_csr_read_4(__csr_num + 4, __val)}
441#define switchcase_csr_read_16(__csr_num, __val) {\
442 switchcase_csr_read_8(__csr_num + 0, __val) \
443 switchcase_csr_read_8(__csr_num + 8, __val)}
444#define switchcase_csr_read_32(__csr_num, __val) {\
445 switchcase_csr_read_16(__csr_num + 0, __val) \
446 switchcase_csr_read_16(__csr_num + 16, __val)}
447
448 unsigned long ret = 0;
449
450 switch (csr_num) {
451 switchcase_csr_read_32(CSR_CYCLE, ret)
452 default:
453 break;
454 }
455
456 return ret;
457#undef switchcase_csr_read_32
458#undef switchcase_csr_read_16
459#undef switchcase_csr_read_8
460#undef switchcase_csr_read_4
461#undef switchcase_csr_read_2
462#undef switchcase_csr_read
463}
464
465static u64 read_perf_counter(unsigned int counter)
466{
467 return csr_read_num(CSR_CYCLE + counter);
468}
469
470static u64 read_timestamp(void)
471{
472 return csr_read_num(CSR_TIME);
473}
474
475#else
476static u64 read_perf_counter(unsigned int counter __maybe_unused) { return 0; }
477static u64 read_timestamp(void) { return 0; }
478#endif
479
480int perf_mmap__read_self(struct perf_mmap *map, struct perf_counts_values *count)
481{
482 struct perf_event_mmap_page *pc = map->base;
483 u32 seq, idx, time_mult = 0, time_shift = 0;
484 u64 cnt, cyc = 0, time_offset = 0, time_cycles = 0, time_mask = ~0ULL;
485
486 if (!pc || !pc->cap_user_rdpmc)
487 return -1;
488
489 do {
490 seq = READ_ONCE(pc->lock);
491 barrier();
492
493 count->ena = READ_ONCE(pc->time_enabled);
494 count->run = READ_ONCE(pc->time_running);
495
496 if (pc->cap_user_time && count->ena != count->run) {
497 cyc = read_timestamp();
498 time_mult = READ_ONCE(pc->time_mult);
499 time_shift = READ_ONCE(pc->time_shift);
500 time_offset = READ_ONCE(pc->time_offset);
501
502 if (pc->cap_user_time_short) {
503 time_cycles = READ_ONCE(pc->time_cycles);
504 time_mask = READ_ONCE(pc->time_mask);
505 }
506 }
507
508 idx = READ_ONCE(pc->index);
509 cnt = READ_ONCE(pc->offset);
510 if (pc->cap_user_rdpmc && idx) {
511 u64 evcnt = read_perf_counter(counter: idx - 1);
512 u16 width = READ_ONCE(pc->pmc_width);
513
514 evcnt <<= 64 - width;
515 evcnt >>= 64 - width;
516 cnt += evcnt;
517 } else
518 return -1;
519
520 barrier();
521 } while (READ_ONCE(pc->lock) != seq);
522
523 if (count->ena != count->run) {
524 u64 delta;
525
526 /* Adjust for cap_usr_time_short, a nop if not */
527 cyc = time_cycles + ((cyc - time_cycles) & time_mask);
528
529 delta = time_offset + mul_u64_u32_shr(a: cyc, mul: time_mult, shift: time_shift);
530
531 count->ena += delta;
532 if (idx)
533 count->run += delta;
534 }
535
536 count->val = cnt;
537
538 return 0;
539}
540

source code of linux/tools/lib/perf/mmap.c