2 * SPDX-License-Identifier: LGPL-2.1-only
4 * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
11 #include <urcu/arch.h>
14 #include <lttng/align.h>
15 #include <lttng/ringbuffer-config.h>
21 #include "ust-compat.h"
24 * lib_ring_buffer_backend_allocate - allocate a channel buffer
25 * @config: ring buffer instance configuration
26 * @buf: the buffer struct
27 * @size: total size of the buffer
28 * @num_subbuf: number of subbuffers
29 * @extra_reader_sb: need extra subbuffer for reader
32 int lib_ring_buffer_backend_allocate(const struct lttng_ust_lib_ring_buffer_config
*config
,
33 struct lttng_ust_lib_ring_buffer_backend
*bufb
,
34 size_t size
, size_t num_subbuf
,
36 struct lttng_ust_shm_handle
*handle
,
37 struct shm_object
*shmobj
)
39 struct channel_backend
*chanb
;
40 unsigned long subbuf_size
, mmap_offset
= 0;
41 unsigned long num_subbuf_alloc
;
45 chanb
= &shmp(handle
, bufb
->chan
)->backend
;
49 subbuf_size
= chanb
->subbuf_size
;
50 num_subbuf_alloc
= num_subbuf
;
55 page_size
= LTTNG_UST_PAGE_SIZE
;
60 align_shm(shmobj
, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages_shmp
));
61 set_shmp(bufb
->array
, zalloc_shm(shmobj
,
62 sizeof(struct lttng_ust_lib_ring_buffer_backend_pages_shmp
) * num_subbuf_alloc
));
63 if (caa_unlikely(!shmp(handle
, bufb
->array
)))
67 * This is the largest element (the buffer pages) which needs to
68 * be aligned on page size.
70 align_shm(shmobj
, page_size
);
71 set_shmp(bufb
->memory_map
, zalloc_shm(shmobj
,
72 subbuf_size
* num_subbuf_alloc
));
73 if (caa_unlikely(!shmp(handle
, bufb
->memory_map
)))
74 goto memory_map_error
;
76 /* Allocate backend pages array elements */
77 for (i
= 0; i
< num_subbuf_alloc
; i
++) {
78 align_shm(shmobj
, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages
));
79 set_shmp(shmp_index(handle
, bufb
->array
, i
)->shmp
,
81 sizeof(struct lttng_ust_lib_ring_buffer_backend_pages
)));
82 if (!shmp(handle
, shmp_index(handle
, bufb
->array
, i
)->shmp
))
86 /* Allocate write-side subbuffer table */
87 align_shm(shmobj
, __alignof__(struct lttng_ust_lib_ring_buffer_backend_subbuffer
));
88 set_shmp(bufb
->buf_wsb
, zalloc_shm(shmobj
,
89 sizeof(struct lttng_ust_lib_ring_buffer_backend_subbuffer
)
91 if (caa_unlikely(!shmp(handle
, bufb
->buf_wsb
)))
94 for (i
= 0; i
< num_subbuf
; i
++) {
95 struct lttng_ust_lib_ring_buffer_backend_subbuffer
*sb
;
97 sb
= shmp_index(handle
, bufb
->buf_wsb
, i
);
100 sb
->id
= subbuffer_id(config
, 0, 1, i
);
103 /* Assign read-side subbuffer table */
105 bufb
->buf_rsb
.id
= subbuffer_id(config
, 0, 1,
106 num_subbuf_alloc
- 1);
108 bufb
->buf_rsb
.id
= subbuffer_id(config
, 0, 1, 0);
110 /* Allocate subbuffer packet counter table */
111 align_shm(shmobj
, __alignof__(struct lttng_ust_lib_ring_buffer_backend_counts
));
112 set_shmp(bufb
->buf_cnt
, zalloc_shm(shmobj
,
113 sizeof(struct lttng_ust_lib_ring_buffer_backend_counts
)
115 if (caa_unlikely(!shmp(handle
, bufb
->buf_cnt
)))
118 /* Assign pages to page index */
119 for (i
= 0; i
< num_subbuf_alloc
; i
++) {
120 struct lttng_ust_lib_ring_buffer_backend_pages_shmp
*sbp
;
121 struct lttng_ust_lib_ring_buffer_backend_pages
*pages
;
124 ref
.index
= bufb
->memory_map
._ref
.index
;
125 ref
.offset
= bufb
->memory_map
._ref
.offset
;
126 ref
.offset
+= i
* subbuf_size
;
128 sbp
= shmp_index(handle
, bufb
->array
, i
);
131 pages
= shmp(handle
, sbp
->shmp
);
134 set_shmp(pages
->p
, ref
);
135 if (config
->output
== RING_BUFFER_MMAP
) {
136 pages
->mmap_offset
= mmap_offset
;
137 mmap_offset
+= subbuf_size
;
143 /* bufb->buf_wsb will be freed by shm teardown */
145 /* bufb->array[i] will be freed by shm teardown */
147 /* bufb->array will be freed by shm teardown */
153 int lib_ring_buffer_backend_create(struct lttng_ust_lib_ring_buffer_backend
*bufb
,
154 struct channel_backend
*chanb
, int cpu
,
155 struct lttng_ust_shm_handle
*handle
,
156 struct shm_object
*shmobj
)
158 const struct lttng_ust_lib_ring_buffer_config
*config
= &chanb
->config
;
160 set_shmp(bufb
->chan
, handle
->chan
._ref
);
163 return lib_ring_buffer_backend_allocate(config
, bufb
, chanb
->buf_size
,
165 chanb
->extra_reader_sb
,
169 void lib_ring_buffer_backend_reset(struct lttng_ust_lib_ring_buffer_backend
*bufb
,
170 struct lttng_ust_shm_handle
*handle
)
172 struct channel_backend
*chanb
;
173 const struct lttng_ust_lib_ring_buffer_config
*config
;
174 unsigned long num_subbuf_alloc
;
177 chanb
= &shmp(handle
, bufb
->chan
)->backend
;
180 config
= &chanb
->config
;
182 num_subbuf_alloc
= chanb
->num_subbuf
;
183 if (chanb
->extra_reader_sb
)
186 for (i
= 0; i
< chanb
->num_subbuf
; i
++) {
187 struct lttng_ust_lib_ring_buffer_backend_subbuffer
*sb
;
189 sb
= shmp_index(handle
, bufb
->buf_wsb
, i
);
192 sb
->id
= subbuffer_id(config
, 0, 1, i
);
194 if (chanb
->extra_reader_sb
)
195 bufb
->buf_rsb
.id
= subbuffer_id(config
, 0, 1,
196 num_subbuf_alloc
- 1);
198 bufb
->buf_rsb
.id
= subbuffer_id(config
, 0, 1, 0);
200 for (i
= 0; i
< num_subbuf_alloc
; i
++) {
201 struct lttng_ust_lib_ring_buffer_backend_pages_shmp
*sbp
;
202 struct lttng_ust_lib_ring_buffer_backend_pages
*pages
;
204 sbp
= shmp_index(handle
, bufb
->array
, i
);
207 pages
= shmp(handle
, sbp
->shmp
);
210 /* Don't reset mmap_offset */
211 v_set(config
, &pages
->records_commit
, 0);
212 v_set(config
, &pages
->records_unread
, 0);
213 pages
->data_size
= 0;
214 /* Don't reset backend page and virt addresses */
216 /* Don't reset num_pages_per_subbuf, cpu, allocated */
217 v_set(config
, &bufb
->records_read
, 0);
221 * The frontend is responsible for also calling ring_buffer_backend_reset for
222 * each buffer when calling channel_backend_reset.
224 void channel_backend_reset(struct channel_backend
*chanb
)
226 struct channel
*chan
= caa_container_of(chanb
, struct channel
, backend
);
227 const struct lttng_ust_lib_ring_buffer_config
*config
= &chanb
->config
;
230 * Don't reset buf_size, subbuf_size, subbuf_size_order,
231 * num_subbuf_order, buf_size_order, extra_reader_sb, num_subbuf,
232 * priv, notifiers, config, cpumask and name.
234 chanb
->start_tsc
= config
->cb
.ring_buffer_clock_read(chan
);
238 * channel_backend_init - initialize a channel backend
239 * @chanb: channel backend
240 * @name: channel name
241 * @config: client ring buffer configuration
242 * @parent: dentry of parent directory, %NULL for root directory
243 * @subbuf_size: size of sub-buffers (> page size, power of 2)
244 * @num_subbuf: number of sub-buffers (power of 2)
245 * @lttng_ust_shm_handle: shared memory handle
246 * @stream_fds: stream file descriptors.
248 * Returns channel pointer if successful, %NULL otherwise.
250 * Creates per-cpu channel buffers using the sizes and attributes
251 * specified. The created channel buffer files will be named
252 * name_0...name_N-1. File permissions will be %S_IRUSR.
254 * Called with CPU hotplug disabled.
256 int channel_backend_init(struct channel_backend
*chanb
,
258 const struct lttng_ust_lib_ring_buffer_config
*config
,
259 size_t subbuf_size
, size_t num_subbuf
,
260 struct lttng_ust_shm_handle
*handle
,
261 const int *stream_fds
)
263 struct channel
*chan
= caa_container_of(chanb
, struct channel
, backend
);
266 size_t shmsize
= 0, num_subbuf_alloc
;
272 page_size
= LTTNG_UST_PAGE_SIZE
;
273 if (page_size
<= 0) {
276 /* Check that the subbuffer size is larger than a page. */
277 if (subbuf_size
< page_size
)
281 * Make sure the number of subbuffers and subbuffer size are
282 * power of 2, and nonzero.
284 if (!subbuf_size
|| (subbuf_size
& (subbuf_size
- 1)))
286 if (!num_subbuf
|| (num_subbuf
& (num_subbuf
- 1)))
289 * Overwrite mode buffers require at least 2 subbuffers per
292 if (config
->mode
== RING_BUFFER_OVERWRITE
&& num_subbuf
< 2)
295 ret
= subbuffer_id_check_index(config
, num_subbuf
);
299 chanb
->buf_size
= num_subbuf
* subbuf_size
;
300 chanb
->subbuf_size
= subbuf_size
;
301 chanb
->buf_size_order
= get_count_order(chanb
->buf_size
);
302 chanb
->subbuf_size_order
= get_count_order(subbuf_size
);
303 chanb
->num_subbuf_order
= get_count_order(num_subbuf
);
304 chanb
->extra_reader_sb
=
305 (config
->mode
== RING_BUFFER_OVERWRITE
) ? 1 : 0;
306 chanb
->num_subbuf
= num_subbuf
;
307 strncpy(chanb
->name
, name
, NAME_MAX
);
308 chanb
->name
[NAME_MAX
- 1] = '\0';
309 memcpy(&chanb
->config
, config
, sizeof(*config
));
311 /* Per-cpu buffer size: control (prior to backend) */
312 shmsize
= lttng_ust_offset_align(shmsize
, __alignof__(struct lttng_ust_lib_ring_buffer
));
313 shmsize
+= sizeof(struct lttng_ust_lib_ring_buffer
);
314 shmsize
+= lttng_ust_offset_align(shmsize
, __alignof__(struct commit_counters_hot
));
315 shmsize
+= sizeof(struct commit_counters_hot
) * num_subbuf
;
316 shmsize
+= lttng_ust_offset_align(shmsize
, __alignof__(struct commit_counters_cold
));
317 shmsize
+= sizeof(struct commit_counters_cold
) * num_subbuf
;
318 /* Sampled timestamp end */
319 shmsize
+= lttng_ust_offset_align(shmsize
, __alignof__(uint64_t));
320 shmsize
+= sizeof(uint64_t) * num_subbuf
;
322 /* Per-cpu buffer size: backend */
323 /* num_subbuf + 1 is the worse case */
324 num_subbuf_alloc
= num_subbuf
+ 1;
325 shmsize
+= lttng_ust_offset_align(shmsize
, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages_shmp
));
326 shmsize
+= sizeof(struct lttng_ust_lib_ring_buffer_backend_pages_shmp
) * num_subbuf_alloc
;
327 shmsize
+= lttng_ust_offset_align(shmsize
, page_size
);
328 shmsize
+= subbuf_size
* num_subbuf_alloc
;
329 shmsize
+= lttng_ust_offset_align(shmsize
, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages
));
330 shmsize
+= sizeof(struct lttng_ust_lib_ring_buffer_backend_pages
) * num_subbuf_alloc
;
331 shmsize
+= lttng_ust_offset_align(shmsize
, __alignof__(struct lttng_ust_lib_ring_buffer_backend_subbuffer
));
332 shmsize
+= sizeof(struct lttng_ust_lib_ring_buffer_backend_subbuffer
) * num_subbuf
;
333 shmsize
+= lttng_ust_offset_align(shmsize
, __alignof__(struct lttng_ust_lib_ring_buffer_backend_counts
));
334 shmsize
+= sizeof(struct lttng_ust_lib_ring_buffer_backend_counts
) * num_subbuf
;
336 if (config
->alloc
== RING_BUFFER_ALLOC_PER_CPU
) {
337 struct lttng_ust_lib_ring_buffer
*buf
;
339 * We need to allocate for all possible cpus.
341 for_each_possible_cpu(i
) {
342 struct shm_object
*shmobj
;
344 shmobj
= shm_object_table_alloc(handle
->table
, shmsize
,
345 SHM_OBJECT_SHM
, stream_fds
[i
], i
);
348 align_shm(shmobj
, __alignof__(struct lttng_ust_lib_ring_buffer
));
349 set_shmp(chanb
->buf
[i
].shmp
, zalloc_shm(shmobj
, sizeof(struct lttng_ust_lib_ring_buffer
)));
350 buf
= shmp(handle
, chanb
->buf
[i
].shmp
);
353 set_shmp(buf
->self
, chanb
->buf
[i
].shmp
._ref
);
354 ret
= lib_ring_buffer_create(buf
, chanb
, i
,
357 goto free_bufs
; /* cpu hotplug locked */
360 struct shm_object
*shmobj
;
361 struct lttng_ust_lib_ring_buffer
*buf
;
363 shmobj
= shm_object_table_alloc(handle
->table
, shmsize
,
364 SHM_OBJECT_SHM
, stream_fds
[0], -1);
367 align_shm(shmobj
, __alignof__(struct lttng_ust_lib_ring_buffer
));
368 set_shmp(chanb
->buf
[0].shmp
, zalloc_shm(shmobj
, sizeof(struct lttng_ust_lib_ring_buffer
)));
369 buf
= shmp(handle
, chanb
->buf
[0].shmp
);
372 set_shmp(buf
->self
, chanb
->buf
[0].shmp
._ref
);
373 ret
= lib_ring_buffer_create(buf
, chanb
, -1,
378 chanb
->start_tsc
= config
->cb
.ring_buffer_clock_read(chan
);
383 /* We only free the buffer data upon shm teardown */
389 * channel_backend_free - destroy the channel
392 * Destroy all channel buffers and frees the channel.
394 void channel_backend_free(struct channel_backend
*chanb
,
395 struct lttng_ust_shm_handle
*handle
)
397 /* SHM teardown takes care of everything */
401 * lib_ring_buffer_read - read data from ring_buffer_buffer.
402 * @bufb : buffer backend
403 * @offset : offset within the buffer
404 * @dest : destination address
405 * @len : length to copy to destination
407 * Should be protected by get_subbuf/put_subbuf.
408 * Returns the length copied.
410 size_t lib_ring_buffer_read(struct lttng_ust_lib_ring_buffer_backend
*bufb
, size_t offset
,
411 void *dest
, size_t len
, struct lttng_ust_shm_handle
*handle
)
413 struct channel_backend
*chanb
;
414 const struct lttng_ust_lib_ring_buffer_config
*config
;
416 struct lttng_ust_lib_ring_buffer_backend_pages_shmp
*rpages
;
417 struct lttng_ust_lib_ring_buffer_backend_pages
*backend_pages
;
418 unsigned long sb_bindex
, id
;
421 chanb
= &shmp(handle
, bufb
->chan
)->backend
;
424 config
= &chanb
->config
;
426 offset
&= chanb
->buf_size
- 1;
428 if (caa_unlikely(!len
))
430 id
= bufb
->buf_rsb
.id
;
431 sb_bindex
= subbuffer_id_get_index(config
, id
);
432 rpages
= shmp_index(handle
, bufb
->array
, sb_bindex
);
436 * Underlying layer should never ask for reads across
439 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
440 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
441 && subbuffer_id_is_noref(config
, id
));
442 backend_pages
= shmp(handle
, rpages
->shmp
);
445 src
= shmp_index(handle
, backend_pages
->p
, offset
& (chanb
->subbuf_size
- 1));
446 if (caa_unlikely(!src
))
448 memcpy(dest
, src
, len
);
453 * lib_ring_buffer_read_cstr - read a C-style string from ring_buffer.
454 * @bufb : buffer backend
455 * @offset : offset within the buffer
456 * @dest : destination address
457 * @len : destination's length
459 * Return string's length, or -EINVAL on error.
460 * Should be protected by get_subbuf/put_subbuf.
461 * Destination length should be at least 1 to hold '\0'.
463 int lib_ring_buffer_read_cstr(struct lttng_ust_lib_ring_buffer_backend
*bufb
, size_t offset
,
464 void *dest
, size_t len
, struct lttng_ust_shm_handle
*handle
)
466 struct channel_backend
*chanb
;
467 const struct lttng_ust_lib_ring_buffer_config
*config
;
468 ssize_t string_len
, orig_offset
;
470 struct lttng_ust_lib_ring_buffer_backend_pages_shmp
*rpages
;
471 struct lttng_ust_lib_ring_buffer_backend_pages
*backend_pages
;
472 unsigned long sb_bindex
, id
;
474 chanb
= &shmp(handle
, bufb
->chan
)->backend
;
477 config
= &chanb
->config
;
478 if (caa_unlikely(!len
))
480 offset
&= chanb
->buf_size
- 1;
481 orig_offset
= offset
;
482 id
= bufb
->buf_rsb
.id
;
483 sb_bindex
= subbuffer_id_get_index(config
, id
);
484 rpages
= shmp_index(handle
, bufb
->array
, sb_bindex
);
488 * Underlying layer should never ask for reads across
491 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
492 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
493 && subbuffer_id_is_noref(config
, id
));
494 backend_pages
= shmp(handle
, rpages
->shmp
);
497 str
= shmp_index(handle
, backend_pages
->p
, offset
& (chanb
->subbuf_size
- 1));
498 if (caa_unlikely(!str
))
500 string_len
= strnlen(str
, len
);
502 memcpy(dest
, str
, string_len
);
503 ((char *)dest
)[0] = 0;
505 return offset
- orig_offset
;
509 * lib_ring_buffer_read_offset_address - get address of a buffer location
510 * @bufb : buffer backend
511 * @offset : offset within the buffer.
513 * Return the address where a given offset is located (for read).
514 * Should be used to get the current subbuffer header pointer. Given we know
515 * it's never on a page boundary, it's safe to read/write directly
516 * from/to this address, as long as the read/write is never bigger than
519 void *lib_ring_buffer_read_offset_address(struct lttng_ust_lib_ring_buffer_backend
*bufb
,
521 struct lttng_ust_shm_handle
*handle
)
523 struct lttng_ust_lib_ring_buffer_backend_pages_shmp
*rpages
;
524 struct lttng_ust_lib_ring_buffer_backend_pages
*backend_pages
;
525 struct channel_backend
*chanb
;
526 const struct lttng_ust_lib_ring_buffer_config
*config
;
527 unsigned long sb_bindex
, id
;
529 chanb
= &shmp(handle
, bufb
->chan
)->backend
;
532 config
= &chanb
->config
;
533 offset
&= chanb
->buf_size
- 1;
534 id
= bufb
->buf_rsb
.id
;
535 sb_bindex
= subbuffer_id_get_index(config
, id
);
536 rpages
= shmp_index(handle
, bufb
->array
, sb_bindex
);
539 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
540 && subbuffer_id_is_noref(config
, id
));
541 backend_pages
= shmp(handle
, rpages
->shmp
);
544 return shmp_index(handle
, backend_pages
->p
, offset
& (chanb
->subbuf_size
- 1));
548 * lib_ring_buffer_offset_address - get address of a location within the buffer
549 * @bufb : buffer backend
550 * @offset : offset within the buffer.
552 * Return the address where a given offset is located.
553 * Should be used to get the current subbuffer header pointer. Given we know
554 * it's always at the beginning of a page, it's safe to write directly to this
555 * address, as long as the write is never bigger than a page size.
557 void *lib_ring_buffer_offset_address(struct lttng_ust_lib_ring_buffer_backend
*bufb
,
559 struct lttng_ust_shm_handle
*handle
)
562 struct lttng_ust_lib_ring_buffer_backend_pages_shmp
*rpages
;
563 struct lttng_ust_lib_ring_buffer_backend_pages
*backend_pages
;
564 struct channel_backend
*chanb
;
565 const struct lttng_ust_lib_ring_buffer_config
*config
;
566 unsigned long sb_bindex
, id
;
567 struct lttng_ust_lib_ring_buffer_backend_subbuffer
*sb
;
569 chanb
= &shmp(handle
, bufb
->chan
)->backend
;
572 config
= &chanb
->config
;
573 offset
&= chanb
->buf_size
- 1;
574 sbidx
= offset
>> chanb
->subbuf_size_order
;
575 sb
= shmp_index(handle
, bufb
->buf_wsb
, sbidx
);
579 sb_bindex
= subbuffer_id_get_index(config
, id
);
580 rpages
= shmp_index(handle
, bufb
->array
, sb_bindex
);
583 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
584 && subbuffer_id_is_noref(config
, id
));
585 backend_pages
= shmp(handle
, rpages
->shmp
);
588 return shmp_index(handle
, backend_pages
->p
, offset
& (chanb
->subbuf_size
- 1));