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852c2936 | 1 | /* |
c0c0989a | 2 | * SPDX-License-Identifier: LGPL-2.1-only |
852c2936 | 3 | * |
e92f3e28 MD |
4 | * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
5 | * | |
c0c0989a | 6 | * Ring buffer backend (internal helpers). |
852c2936 MD |
7 | */ |
8 | ||
c0c0989a MJ |
9 | #ifndef _LTTNG_RING_BUFFER_BACKEND_INTERNAL_H |
10 | #define _LTTNG_RING_BUFFER_BACKEND_INTERNAL_H | |
11 | ||
b4051ad8 | 12 | #include <stddef.h> |
fb31eb73 | 13 | #include <stdint.h> |
14641deb MD |
14 | #include <unistd.h> |
15 | #include <urcu/compiler.h> | |
16 | ||
0466ac28 MD |
17 | #include <lttng/ringbuffer-context.h> |
18 | #include "ringbuffer-config.h" | |
4931a13e MD |
19 | #include "backend_types.h" |
20 | #include "frontend_types.h" | |
a6352fd4 | 21 | #include "shm.h" |
852c2936 MD |
22 | |
23 | /* Ring buffer backend API presented to the frontend */ | |
24 | ||
25 | /* Ring buffer and channel backend create/free */ | |
26 | ||
ddabe860 | 27 | __attribute__((visibility("hidden"))) |
4cfec15c | 28 | int lib_ring_buffer_backend_create(struct lttng_ust_lib_ring_buffer_backend *bufb, |
5198080d MJ |
29 | struct channel_backend *chan, |
30 | int cpu, | |
38fae1d3 | 31 | struct lttng_ust_shm_handle *handle, |
1d498196 | 32 | struct shm_object *shmobj); |
ddabe860 MJ |
33 | |
34 | __attribute__((visibility("hidden"))) | |
852c2936 | 35 | void channel_backend_unregister_notifiers(struct channel_backend *chanb); |
ddabe860 MJ |
36 | |
37 | __attribute__((visibility("hidden"))) | |
4cfec15c | 38 | void lib_ring_buffer_backend_free(struct lttng_ust_lib_ring_buffer_backend *bufb); |
ddabe860 MJ |
39 | |
40 | __attribute__((visibility("hidden"))) | |
852c2936 MD |
41 | int channel_backend_init(struct channel_backend *chanb, |
42 | const char *name, | |
4cfec15c | 43 | const struct lttng_ust_lib_ring_buffer_config *config, |
a3f61e7f | 44 | size_t subbuf_size, |
a9ff648c | 45 | size_t num_subbuf, struct lttng_ust_shm_handle *handle, |
5ea386c3 | 46 | const int *stream_fds); |
ddabe860 MJ |
47 | |
48 | __attribute__((visibility("hidden"))) | |
1d498196 | 49 | void channel_backend_free(struct channel_backend *chanb, |
38fae1d3 | 50 | struct lttng_ust_shm_handle *handle); |
852c2936 | 51 | |
ddabe860 | 52 | __attribute__((visibility("hidden"))) |
4cfec15c | 53 | void lib_ring_buffer_backend_reset(struct lttng_ust_lib_ring_buffer_backend *bufb, |
38fae1d3 | 54 | struct lttng_ust_shm_handle *handle); |
ddabe860 MJ |
55 | |
56 | __attribute__((visibility("hidden"))) | |
852c2936 MD |
57 | void channel_backend_reset(struct channel_backend *chanb); |
58 | ||
ddabe860 | 59 | __attribute__((visibility("hidden"))) |
852c2936 | 60 | int lib_ring_buffer_backend_init(void); |
ddabe860 MJ |
61 | |
62 | __attribute__((visibility("hidden"))) | |
852c2936 MD |
63 | void lib_ring_buffer_backend_exit(void); |
64 | ||
ddabe860 | 65 | __attribute__((visibility("hidden"))) |
4cfec15c | 66 | extern void _lib_ring_buffer_write(struct lttng_ust_lib_ring_buffer_backend *bufb, |
852c2936 MD |
67 | size_t offset, const void *src, size_t len, |
68 | ssize_t pagecpy); | |
69 | ||
70 | /* | |
71 | * Subbuffer ID bits for overwrite mode. Need to fit within a single word to be | |
72 | * exchanged atomically. | |
73 | * | |
74 | * Top half word, except lowest bit, belongs to "offset", which is used to keep | |
75 | * to count the produced buffers. For overwrite mode, this provides the | |
76 | * consumer with the capacity to read subbuffers in order, handling the | |
77 | * situation where producers would write up to 2^15 buffers (or 2^31 for 64-bit | |
78 | * systems) concurrently with a single execution of get_subbuf (between offset | |
79 | * sampling and subbuffer ID exchange). | |
80 | */ | |
81 | ||
14641deb | 82 | #define HALF_ULONG_BITS (CAA_BITS_PER_LONG >> 1) |
852c2936 MD |
83 | |
84 | #define SB_ID_OFFSET_SHIFT (HALF_ULONG_BITS + 1) | |
85 | #define SB_ID_OFFSET_COUNT (1UL << SB_ID_OFFSET_SHIFT) | |
86 | #define SB_ID_OFFSET_MASK (~(SB_ID_OFFSET_COUNT - 1)) | |
87 | /* | |
88 | * Lowest bit of top word half belongs to noref. Used only for overwrite mode. | |
89 | */ | |
90 | #define SB_ID_NOREF_SHIFT (SB_ID_OFFSET_SHIFT - 1) | |
91 | #define SB_ID_NOREF_COUNT (1UL << SB_ID_NOREF_SHIFT) | |
92 | #define SB_ID_NOREF_MASK SB_ID_NOREF_COUNT | |
93 | /* | |
94 | * In overwrite mode: lowest half of word is used for index. | |
95 | * Limit of 2^16 subbuffers per buffer on 32-bit, 2^32 on 64-bit. | |
96 | * In producer-consumer mode: whole word used for index. | |
97 | */ | |
98 | #define SB_ID_INDEX_SHIFT 0 | |
99 | #define SB_ID_INDEX_COUNT (1UL << SB_ID_INDEX_SHIFT) | |
100 | #define SB_ID_INDEX_MASK (SB_ID_NOREF_COUNT - 1) | |
101 | ||
102 | /* | |
103 | * Construct the subbuffer id from offset, index and noref. Use only the index | |
104 | * for producer-consumer mode (offset and noref are only used in overwrite | |
105 | * mode). | |
106 | */ | |
107 | static inline | |
4cfec15c | 108 | unsigned long subbuffer_id(const struct lttng_ust_lib_ring_buffer_config *config, |
852c2936 MD |
109 | unsigned long offset, unsigned long noref, |
110 | unsigned long index) | |
111 | { | |
112 | if (config->mode == RING_BUFFER_OVERWRITE) | |
113 | return (offset << SB_ID_OFFSET_SHIFT) | |
114 | | (noref << SB_ID_NOREF_SHIFT) | |
115 | | index; | |
116 | else | |
117 | return index; | |
118 | } | |
119 | ||
120 | /* | |
121 | * Compare offset with the offset contained within id. Return 1 if the offset | |
122 | * bits are identical, else 0. | |
123 | */ | |
124 | static inline | |
4cfec15c | 125 | int subbuffer_id_compare_offset(const struct lttng_ust_lib_ring_buffer_config *config, |
852c2936 MD |
126 | unsigned long id, unsigned long offset) |
127 | { | |
128 | return (id & SB_ID_OFFSET_MASK) == (offset << SB_ID_OFFSET_SHIFT); | |
129 | } | |
130 | ||
131 | static inline | |
4cfec15c | 132 | unsigned long subbuffer_id_get_index(const struct lttng_ust_lib_ring_buffer_config *config, |
852c2936 MD |
133 | unsigned long id) |
134 | { | |
135 | if (config->mode == RING_BUFFER_OVERWRITE) | |
136 | return id & SB_ID_INDEX_MASK; | |
137 | else | |
138 | return id; | |
139 | } | |
140 | ||
141 | static inline | |
4cfec15c | 142 | unsigned long subbuffer_id_is_noref(const struct lttng_ust_lib_ring_buffer_config *config, |
852c2936 MD |
143 | unsigned long id) |
144 | { | |
145 | if (config->mode == RING_BUFFER_OVERWRITE) | |
146 | return !!(id & SB_ID_NOREF_MASK); | |
147 | else | |
148 | return 1; | |
149 | } | |
150 | ||
151 | /* | |
152 | * Only used by reader on subbuffer ID it has exclusive access to. No volatile | |
153 | * needed. | |
154 | */ | |
155 | static inline | |
4cfec15c | 156 | void subbuffer_id_set_noref(const struct lttng_ust_lib_ring_buffer_config *config, |
852c2936 MD |
157 | unsigned long *id) |
158 | { | |
159 | if (config->mode == RING_BUFFER_OVERWRITE) | |
160 | *id |= SB_ID_NOREF_MASK; | |
161 | } | |
162 | ||
163 | static inline | |
4cfec15c | 164 | void subbuffer_id_set_noref_offset(const struct lttng_ust_lib_ring_buffer_config *config, |
852c2936 MD |
165 | unsigned long *id, unsigned long offset) |
166 | { | |
167 | unsigned long tmp; | |
168 | ||
169 | if (config->mode == RING_BUFFER_OVERWRITE) { | |
170 | tmp = *id; | |
171 | tmp &= ~SB_ID_OFFSET_MASK; | |
172 | tmp |= offset << SB_ID_OFFSET_SHIFT; | |
173 | tmp |= SB_ID_NOREF_MASK; | |
174 | /* Volatile store, read concurrently by readers. */ | |
14641deb | 175 | CMM_ACCESS_ONCE(*id) = tmp; |
852c2936 MD |
176 | } |
177 | } | |
178 | ||
179 | /* No volatile access, since already used locally */ | |
180 | static inline | |
4cfec15c | 181 | void subbuffer_id_clear_noref(const struct lttng_ust_lib_ring_buffer_config *config, |
852c2936 MD |
182 | unsigned long *id) |
183 | { | |
184 | if (config->mode == RING_BUFFER_OVERWRITE) | |
185 | *id &= ~SB_ID_NOREF_MASK; | |
186 | } | |
187 | ||
188 | /* | |
189 | * For overwrite mode, cap the number of subbuffers per buffer to: | |
190 | * 2^16 on 32-bit architectures | |
191 | * 2^32 on 64-bit architectures | |
192 | * This is required to fit in the index part of the ID. Return 0 on success, | |
193 | * -EPERM on failure. | |
194 | */ | |
195 | static inline | |
4cfec15c | 196 | int subbuffer_id_check_index(const struct lttng_ust_lib_ring_buffer_config *config, |
852c2936 MD |
197 | unsigned long num_subbuf) |
198 | { | |
199 | if (config->mode == RING_BUFFER_OVERWRITE) | |
200 | return (num_subbuf > (1UL << HALF_ULONG_BITS)) ? -EPERM : 0; | |
201 | else | |
202 | return 0; | |
203 | } | |
204 | ||
a3492932 MD |
205 | static inline |
206 | int lib_ring_buffer_backend_get_pages(const struct lttng_ust_lib_ring_buffer_config *config, | |
207 | struct lttng_ust_lib_ring_buffer_ctx *ctx, | |
208 | struct lttng_ust_lib_ring_buffer_backend_pages **backend_pages) | |
209 | { | |
8936b6c0 MD |
210 | struct lttng_ust_lib_ring_buffer_ctx_private *ctx_private = ctx->priv; |
211 | struct lttng_ust_lib_ring_buffer_backend *bufb = &ctx_private->buf->backend; | |
212 | struct channel_backend *chanb = &ctx_private->chan->backend; | |
213 | struct lttng_ust_shm_handle *handle = ctx_private->chan->handle; | |
a3492932 | 214 | size_t sbidx; |
8936b6c0 | 215 | size_t offset = ctx_private->buf_offset; |
a3492932 MD |
216 | struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb; |
217 | struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages; | |
218 | unsigned long sb_bindex, id; | |
219 | struct lttng_ust_lib_ring_buffer_backend_pages *_backend_pages; | |
220 | ||
221 | offset &= chanb->buf_size - 1; | |
222 | sbidx = offset >> chanb->subbuf_size_order; | |
223 | wsb = shmp_index(handle, bufb->buf_wsb, sbidx); | |
224 | if (caa_unlikely(!wsb)) | |
225 | return -1; | |
226 | id = wsb->id; | |
227 | sb_bindex = subbuffer_id_get_index(config, id); | |
228 | rpages = shmp_index(handle, bufb->array, sb_bindex); | |
229 | if (caa_unlikely(!rpages)) | |
230 | return -1; | |
8936b6c0 | 231 | CHAN_WARN_ON(ctx_private->chan, |
a3492932 MD |
232 | config->mode == RING_BUFFER_OVERWRITE |
233 | && subbuffer_id_is_noref(config, id)); | |
234 | _backend_pages = shmp(handle, rpages->shmp); | |
235 | if (caa_unlikely(!_backend_pages)) | |
236 | return -1; | |
237 | *backend_pages = _backend_pages; | |
238 | return 0; | |
239 | } | |
240 | ||
241 | /* Get backend pages from cache. */ | |
242 | static inline | |
243 | struct lttng_ust_lib_ring_buffer_backend_pages * | |
244 | lib_ring_buffer_get_backend_pages_from_ctx(const struct lttng_ust_lib_ring_buffer_config *config, | |
245 | struct lttng_ust_lib_ring_buffer_ctx *ctx) | |
246 | { | |
8936b6c0 | 247 | return ctx->priv->backend_pages; |
a3492932 MD |
248 | } |
249 | ||
9c995331 MD |
250 | /* |
251 | * The ring buffer can count events recorded and overwritten per buffer, | |
252 | * but it is disabled by default due to its performance overhead. | |
253 | */ | |
254 | #ifdef LTTNG_RING_BUFFER_COUNT_EVENTS | |
852c2936 | 255 | static inline |
4cfec15c | 256 | void subbuffer_count_record(const struct lttng_ust_lib_ring_buffer_config *config, |
15500a1b | 257 | const struct lttng_ust_lib_ring_buffer_ctx *ctx, |
4cfec15c | 258 | struct lttng_ust_lib_ring_buffer_backend *bufb, |
38fae1d3 | 259 | unsigned long idx, struct lttng_ust_shm_handle *handle) |
852c2936 | 260 | { |
15500a1b | 261 | struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages; |
852c2936 | 262 | |
15500a1b MD |
263 | backend_pages = lib_ring_buffer_get_backend_pages_from_ctx(config, ctx); |
264 | if (caa_unlikely(!backend_pages)) { | |
265 | if (lib_ring_buffer_backend_get_pages(config, ctx, &backend_pages)) | |
266 | return; | |
267 | } | |
268 | v_inc(config, &backend_pages->records_commit); | |
852c2936 | 269 | } |
9c995331 MD |
270 | #else /* LTTNG_RING_BUFFER_COUNT_EVENTS */ |
271 | static inline | |
272 | void subbuffer_count_record(const struct lttng_ust_lib_ring_buffer_config *config, | |
15500a1b | 273 | const struct lttng_ust_lib_ring_buffer_ctx *ctx, |
9c995331 MD |
274 | struct lttng_ust_lib_ring_buffer_backend *bufb, |
275 | unsigned long idx, struct lttng_ust_shm_handle *handle) | |
276 | { | |
277 | } | |
278 | #endif /* #else LTTNG_RING_BUFFER_COUNT_EVENTS */ | |
852c2936 MD |
279 | |
280 | /* | |
281 | * Reader has exclusive subbuffer access for record consumption. No need to | |
282 | * perform the decrement atomically. | |
283 | */ | |
284 | static inline | |
4cfec15c MD |
285 | void subbuffer_consume_record(const struct lttng_ust_lib_ring_buffer_config *config, |
286 | struct lttng_ust_lib_ring_buffer_backend *bufb, | |
38fae1d3 | 287 | struct lttng_ust_shm_handle *handle) |
852c2936 MD |
288 | { |
289 | unsigned long sb_bindex; | |
5198080d | 290 | struct lttng_ust_lib_ring_buffer_channel *chan; |
15500a1b MD |
291 | struct lttng_ust_lib_ring_buffer_backend_pages_shmp *pages_shmp; |
292 | struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages; | |
852c2936 MD |
293 | |
294 | sb_bindex = subbuffer_id_get_index(config, bufb->buf_rsb.id); | |
15500a1b MD |
295 | chan = shmp(handle, bufb->chan); |
296 | if (!chan) | |
297 | return; | |
298 | pages_shmp = shmp_index(handle, bufb->array, sb_bindex); | |
299 | if (!pages_shmp) | |
300 | return; | |
301 | backend_pages = shmp(handle, pages_shmp->shmp); | |
302 | if (!backend_pages) | |
303 | return; | |
304 | CHAN_WARN_ON(chan, !v_read(config, &backend_pages->records_unread)); | |
852c2936 | 305 | /* Non-atomic decrement protected by exclusive subbuffer access */ |
15500a1b | 306 | _v_dec(config, &backend_pages->records_unread); |
852c2936 MD |
307 | v_inc(config, &bufb->records_read); |
308 | } | |
309 | ||
310 | static inline | |
311 | unsigned long subbuffer_get_records_count( | |
4cfec15c MD |
312 | const struct lttng_ust_lib_ring_buffer_config *config, |
313 | struct lttng_ust_lib_ring_buffer_backend *bufb, | |
1d498196 | 314 | unsigned long idx, |
38fae1d3 | 315 | struct lttng_ust_shm_handle *handle) |
852c2936 MD |
316 | { |
317 | unsigned long sb_bindex; | |
15500a1b MD |
318 | struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb; |
319 | struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages; | |
320 | struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages; | |
852c2936 | 321 | |
15500a1b MD |
322 | wsb = shmp_index(handle, bufb->buf_wsb, idx); |
323 | if (!wsb) | |
324 | return 0; | |
325 | sb_bindex = subbuffer_id_get_index(config, wsb->id); | |
326 | rpages = shmp_index(handle, bufb->array, sb_bindex); | |
327 | if (!rpages) | |
328 | return 0; | |
329 | backend_pages = shmp(handle, rpages->shmp); | |
330 | if (!backend_pages) | |
331 | return 0; | |
332 | return v_read(config, &backend_pages->records_commit); | |
852c2936 MD |
333 | } |
334 | ||
335 | /* | |
336 | * Must be executed at subbuffer delivery when the writer has _exclusive_ | |
3d1aec25 MD |
337 | * subbuffer access. See lib_ring_buffer_check_deliver() for details. |
338 | * lib_ring_buffer_get_records_count() must be called to get the records | |
339 | * count before this function, because it resets the records_commit | |
340 | * count. | |
852c2936 MD |
341 | */ |
342 | static inline | |
343 | unsigned long subbuffer_count_records_overrun( | |
4cfec15c MD |
344 | const struct lttng_ust_lib_ring_buffer_config *config, |
345 | struct lttng_ust_lib_ring_buffer_backend *bufb, | |
1d498196 | 346 | unsigned long idx, |
38fae1d3 | 347 | struct lttng_ust_shm_handle *handle) |
852c2936 | 348 | { |
852c2936 | 349 | unsigned long overruns, sb_bindex; |
15500a1b MD |
350 | struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb; |
351 | struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages; | |
352 | struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages; | |
852c2936 | 353 | |
15500a1b MD |
354 | wsb = shmp_index(handle, bufb->buf_wsb, idx); |
355 | if (!wsb) | |
356 | return 0; | |
357 | sb_bindex = subbuffer_id_get_index(config, wsb->id); | |
358 | rpages = shmp_index(handle, bufb->array, sb_bindex); | |
359 | if (!rpages) | |
360 | return 0; | |
361 | backend_pages = shmp(handle, rpages->shmp); | |
362 | if (!backend_pages) | |
363 | return 0; | |
364 | overruns = v_read(config, &backend_pages->records_unread); | |
365 | v_set(config, &backend_pages->records_unread, | |
366 | v_read(config, &backend_pages->records_commit)); | |
367 | v_set(config, &backend_pages->records_commit, 0); | |
852c2936 MD |
368 | |
369 | return overruns; | |
370 | } | |
371 | ||
372 | static inline | |
4cfec15c MD |
373 | void subbuffer_set_data_size(const struct lttng_ust_lib_ring_buffer_config *config, |
374 | struct lttng_ust_lib_ring_buffer_backend *bufb, | |
852c2936 | 375 | unsigned long idx, |
1d498196 | 376 | unsigned long data_size, |
38fae1d3 | 377 | struct lttng_ust_shm_handle *handle) |
852c2936 | 378 | { |
852c2936 | 379 | unsigned long sb_bindex; |
15500a1b MD |
380 | struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb; |
381 | struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages; | |
382 | struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages; | |
852c2936 | 383 | |
15500a1b MD |
384 | wsb = shmp_index(handle, bufb->buf_wsb, idx); |
385 | if (!wsb) | |
386 | return; | |
387 | sb_bindex = subbuffer_id_get_index(config, wsb->id); | |
388 | rpages = shmp_index(handle, bufb->array, sb_bindex); | |
389 | if (!rpages) | |
390 | return; | |
391 | backend_pages = shmp(handle, rpages->shmp); | |
392 | if (!backend_pages) | |
393 | return; | |
394 | backend_pages->data_size = data_size; | |
852c2936 MD |
395 | } |
396 | ||
397 | static inline | |
398 | unsigned long subbuffer_get_read_data_size( | |
4cfec15c MD |
399 | const struct lttng_ust_lib_ring_buffer_config *config, |
400 | struct lttng_ust_lib_ring_buffer_backend *bufb, | |
38fae1d3 | 401 | struct lttng_ust_shm_handle *handle) |
852c2936 | 402 | { |
852c2936 | 403 | unsigned long sb_bindex; |
15500a1b MD |
404 | struct lttng_ust_lib_ring_buffer_backend_pages_shmp *pages_shmp; |
405 | struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages; | |
852c2936 MD |
406 | |
407 | sb_bindex = subbuffer_id_get_index(config, bufb->buf_rsb.id); | |
15500a1b MD |
408 | pages_shmp = shmp_index(handle, bufb->array, sb_bindex); |
409 | if (!pages_shmp) | |
410 | return 0; | |
411 | backend_pages = shmp(handle, pages_shmp->shmp); | |
412 | if (!backend_pages) | |
413 | return 0; | |
414 | return backend_pages->data_size; | |
852c2936 MD |
415 | } |
416 | ||
417 | static inline | |
418 | unsigned long subbuffer_get_data_size( | |
4cfec15c MD |
419 | const struct lttng_ust_lib_ring_buffer_config *config, |
420 | struct lttng_ust_lib_ring_buffer_backend *bufb, | |
1d498196 | 421 | unsigned long idx, |
38fae1d3 | 422 | struct lttng_ust_shm_handle *handle) |
852c2936 | 423 | { |
852c2936 | 424 | unsigned long sb_bindex; |
15500a1b MD |
425 | struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb; |
426 | struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages; | |
427 | struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages; | |
852c2936 | 428 | |
15500a1b MD |
429 | wsb = shmp_index(handle, bufb->buf_wsb, idx); |
430 | if (!wsb) | |
431 | return 0; | |
432 | sb_bindex = subbuffer_id_get_index(config, wsb->id); | |
433 | rpages = shmp_index(handle, bufb->array, sb_bindex); | |
434 | if (!rpages) | |
435 | return 0; | |
436 | backend_pages = shmp(handle, rpages->shmp); | |
437 | if (!backend_pages) | |
438 | return 0; | |
439 | return backend_pages->data_size; | |
852c2936 MD |
440 | } |
441 | ||
1ff31389 JD |
442 | static inline |
443 | void subbuffer_inc_packet_count(const struct lttng_ust_lib_ring_buffer_config *config, | |
444 | struct lttng_ust_lib_ring_buffer_backend *bufb, | |
445 | unsigned long idx, struct lttng_ust_shm_handle *handle) | |
446 | { | |
15500a1b MD |
447 | struct lttng_ust_lib_ring_buffer_backend_counts *counts; |
448 | ||
449 | counts = shmp_index(handle, bufb->buf_cnt, idx); | |
450 | if (!counts) | |
451 | return; | |
452 | counts->seq_cnt++; | |
1ff31389 JD |
453 | } |
454 | ||
852c2936 MD |
455 | /** |
456 | * lib_ring_buffer_clear_noref - Clear the noref subbuffer flag, called by | |
457 | * writer. | |
458 | */ | |
459 | static inline | |
4cfec15c MD |
460 | void lib_ring_buffer_clear_noref(const struct lttng_ust_lib_ring_buffer_config *config, |
461 | struct lttng_ust_lib_ring_buffer_backend *bufb, | |
1d498196 | 462 | unsigned long idx, |
38fae1d3 | 463 | struct lttng_ust_shm_handle *handle) |
852c2936 MD |
464 | { |
465 | unsigned long id, new_id; | |
15500a1b | 466 | struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb; |
852c2936 MD |
467 | |
468 | if (config->mode != RING_BUFFER_OVERWRITE) | |
469 | return; | |
470 | ||
471 | /* | |
472 | * Performing a volatile access to read the sb_pages, because we want to | |
473 | * read a coherent version of the pointer and the associated noref flag. | |
474 | */ | |
15500a1b MD |
475 | wsb = shmp_index(handle, bufb->buf_wsb, idx); |
476 | if (!wsb) | |
477 | return; | |
478 | id = CMM_ACCESS_ONCE(wsb->id); | |
852c2936 MD |
479 | for (;;) { |
480 | /* This check is called on the fast path for each record. */ | |
b5a3dfa5 | 481 | if (caa_likely(!subbuffer_id_is_noref(config, id))) { |
852c2936 MD |
482 | /* |
483 | * Store after load dependency ordering the writes to | |
484 | * the subbuffer after load and test of the noref flag | |
485 | * matches the memory barrier implied by the cmpxchg() | |
486 | * in update_read_sb_index(). | |
487 | */ | |
488 | return; /* Already writing to this buffer */ | |
489 | } | |
490 | new_id = id; | |
491 | subbuffer_id_clear_noref(config, &new_id); | |
15500a1b | 492 | new_id = uatomic_cmpxchg(&wsb->id, id, new_id); |
b5a3dfa5 | 493 | if (caa_likely(new_id == id)) |
852c2936 MD |
494 | break; |
495 | id = new_id; | |
496 | } | |
497 | } | |
498 | ||
499 | /** | |
500 | * lib_ring_buffer_set_noref_offset - Set the noref subbuffer flag and offset, | |
501 | * called by writer. | |
502 | */ | |
503 | static inline | |
4cfec15c MD |
504 | void lib_ring_buffer_set_noref_offset(const struct lttng_ust_lib_ring_buffer_config *config, |
505 | struct lttng_ust_lib_ring_buffer_backend *bufb, | |
1d498196 | 506 | unsigned long idx, unsigned long offset, |
38fae1d3 | 507 | struct lttng_ust_shm_handle *handle) |
852c2936 | 508 | { |
15500a1b | 509 | struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb; |
5198080d | 510 | struct lttng_ust_lib_ring_buffer_channel *chan; |
15500a1b | 511 | |
852c2936 MD |
512 | if (config->mode != RING_BUFFER_OVERWRITE) |
513 | return; | |
514 | ||
15500a1b MD |
515 | wsb = shmp_index(handle, bufb->buf_wsb, idx); |
516 | if (!wsb) | |
517 | return; | |
852c2936 MD |
518 | /* |
519 | * Because ring_buffer_set_noref() is only called by a single thread | |
520 | * (the one which updated the cc_sb value), there are no concurrent | |
521 | * updates to take care of: other writers have not updated cc_sb, so | |
522 | * they cannot set the noref flag, and concurrent readers cannot modify | |
523 | * the pointer because the noref flag is not set yet. | |
524 | * The smp_wmb() in ring_buffer_commit() takes care of ordering writes | |
525 | * to the subbuffer before this set noref operation. | |
526 | * subbuffer_set_noref() uses a volatile store to deal with concurrent | |
527 | * readers of the noref flag. | |
528 | */ | |
15500a1b MD |
529 | chan = shmp(handle, bufb->chan); |
530 | if (!chan) | |
531 | return; | |
532 | CHAN_WARN_ON(chan, subbuffer_id_is_noref(config, wsb->id)); | |
852c2936 MD |
533 | /* |
534 | * Memory barrier that ensures counter stores are ordered before set | |
535 | * noref and offset. | |
536 | */ | |
14641deb | 537 | cmm_smp_mb(); |
15500a1b | 538 | subbuffer_id_set_noref_offset(config, &wsb->id, offset); |
852c2936 MD |
539 | } |
540 | ||
541 | /** | |
542 | * update_read_sb_index - Read-side subbuffer index update. | |
543 | */ | |
544 | static inline | |
4cfec15c MD |
545 | int update_read_sb_index(const struct lttng_ust_lib_ring_buffer_config *config, |
546 | struct lttng_ust_lib_ring_buffer_backend *bufb, | |
852c2936 MD |
547 | struct channel_backend *chanb, |
548 | unsigned long consumed_idx, | |
1d498196 | 549 | unsigned long consumed_count, |
38fae1d3 | 550 | struct lttng_ust_shm_handle *handle) |
852c2936 | 551 | { |
15500a1b | 552 | struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb; |
852c2936 MD |
553 | unsigned long old_id, new_id; |
554 | ||
15500a1b MD |
555 | wsb = shmp_index(handle, bufb->buf_wsb, consumed_idx); |
556 | if (caa_unlikely(!wsb)) | |
557 | return -EPERM; | |
558 | ||
852c2936 | 559 | if (config->mode == RING_BUFFER_OVERWRITE) { |
5198080d | 560 | struct lttng_ust_lib_ring_buffer_channel *chan; |
15500a1b | 561 | |
852c2936 MD |
562 | /* |
563 | * Exchange the target writer subbuffer with our own unused | |
14641deb | 564 | * subbuffer. No need to use CMM_ACCESS_ONCE() here to read the |
852c2936 MD |
565 | * old_wpage, because the value read will be confirmed by the |
566 | * following cmpxchg(). | |
567 | */ | |
15500a1b | 568 | old_id = wsb->id; |
b5a3dfa5 | 569 | if (caa_unlikely(!subbuffer_id_is_noref(config, old_id))) |
852c2936 MD |
570 | return -EAGAIN; |
571 | /* | |
572 | * Make sure the offset count we are expecting matches the one | |
573 | * indicated by the writer. | |
574 | */ | |
b5a3dfa5 | 575 | if (caa_unlikely(!subbuffer_id_compare_offset(config, old_id, |
852c2936 MD |
576 | consumed_count))) |
577 | return -EAGAIN; | |
15500a1b MD |
578 | chan = shmp(handle, bufb->chan); |
579 | if (caa_unlikely(!chan)) | |
580 | return -EPERM; | |
581 | CHAN_WARN_ON(chan, !subbuffer_id_is_noref(config, bufb->buf_rsb.id)); | |
852c2936 MD |
582 | subbuffer_id_set_noref_offset(config, &bufb->buf_rsb.id, |
583 | consumed_count); | |
15500a1b | 584 | new_id = uatomic_cmpxchg(&wsb->id, old_id, bufb->buf_rsb.id); |
b5a3dfa5 | 585 | if (caa_unlikely(old_id != new_id)) |
852c2936 MD |
586 | return -EAGAIN; |
587 | bufb->buf_rsb.id = new_id; | |
588 | } else { | |
589 | /* No page exchange, use the writer page directly */ | |
15500a1b | 590 | bufb->buf_rsb.id = wsb->id; |
852c2936 MD |
591 | } |
592 | return 0; | |
593 | } | |
594 | ||
0d4aa2df MD |
595 | #ifndef inline_memcpy |
596 | #define inline_memcpy(dest, src, n) memcpy(dest, src, n) | |
597 | #endif | |
598 | ||
51b8f2fa MD |
599 | static inline __attribute__((always_inline)) |
600 | void lttng_inline_memcpy(void *dest, const void *src, | |
601 | unsigned long len) | |
602 | { | |
603 | switch (len) { | |
604 | case 1: | |
605 | *(uint8_t *) dest = *(const uint8_t *) src; | |
606 | break; | |
607 | case 2: | |
608 | *(uint16_t *) dest = *(const uint16_t *) src; | |
609 | break; | |
610 | case 4: | |
611 | *(uint32_t *) dest = *(const uint32_t *) src; | |
612 | break; | |
613 | case 8: | |
614 | *(uint64_t *) dest = *(const uint64_t *) src; | |
615 | break; | |
616 | default: | |
617 | inline_memcpy(dest, src, len); | |
618 | } | |
619 | } | |
620 | ||
852c2936 MD |
621 | /* |
622 | * Use the architecture-specific memcpy implementation for constant-sized | |
623 | * inputs, but rely on an inline memcpy for length statically unknown. | |
624 | * The function call to memcpy is just way too expensive for a fast path. | |
625 | */ | |
626 | #define lib_ring_buffer_do_copy(config, dest, src, len) \ | |
627 | do { \ | |
628 | size_t __len = (len); \ | |
629 | if (__builtin_constant_p(len)) \ | |
630 | memcpy(dest, src, __len); \ | |
631 | else \ | |
51b8f2fa | 632 | lttng_inline_memcpy(dest, src, __len); \ |
852c2936 MD |
633 | } while (0) |
634 | ||
a44c74d9 MD |
635 | /* |
636 | * write len bytes to dest with c | |
637 | */ | |
638 | static inline | |
b4c8bf2f | 639 | void lib_ring_buffer_do_memset(char *dest, char c, unsigned long len) |
a44c74d9 MD |
640 | { |
641 | unsigned long i; | |
642 | ||
643 | for (i = 0; i < len; i++) | |
644 | dest[i] = c; | |
645 | } | |
646 | ||
b728d87e MD |
647 | /* arch-agnostic implementation */ |
648 | ||
bfd26582 | 649 | static inline int lttng_ust_fls(unsigned int x) |
b728d87e MD |
650 | { |
651 | int r = 32; | |
652 | ||
653 | if (!x) | |
654 | return 0; | |
655 | if (!(x & 0xFFFF0000U)) { | |
656 | x <<= 16; | |
657 | r -= 16; | |
658 | } | |
659 | if (!(x & 0xFF000000U)) { | |
660 | x <<= 8; | |
661 | r -= 8; | |
662 | } | |
663 | if (!(x & 0xF0000000U)) { | |
664 | x <<= 4; | |
665 | r -= 4; | |
666 | } | |
667 | if (!(x & 0xC0000000U)) { | |
668 | x <<= 2; | |
669 | r -= 2; | |
670 | } | |
671 | if (!(x & 0x80000000U)) { | |
e2bd33a5 | 672 | /* No need to bit shift on last operation */ |
b728d87e MD |
673 | r -= 1; |
674 | } | |
675 | return r; | |
676 | } | |
677 | ||
678 | static inline int get_count_order(unsigned int count) | |
679 | { | |
680 | int order; | |
681 | ||
bfd26582 | 682 | order = lttng_ust_fls(count) - 1; |
b728d87e MD |
683 | if (count & (count - 1)) |
684 | order++; | |
685 | return order; | |
686 | } | |
687 | ||
e92f3e28 | 688 | #endif /* _LTTNG_RING_BUFFER_BACKEND_INTERNAL_H */ |