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a6352fd4 | 1 | /* |
c0c0989a | 2 | * SPDX-License-Identifier: MIT |
a6352fd4 | 3 | * |
c0c0989a | 4 | * Copyright (C) 2010 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
a6352fd4 MD |
5 | * |
6 | * Ring buffer configuration header. Note: after declaring the standard inline | |
7 | * functions, clients should also include linux/ringbuffer/api.h. | |
a6352fd4 MD |
8 | */ |
9 | ||
c0c0989a MJ |
10 | #ifndef _LTTNG_RING_BUFFER_CONFIG_H |
11 | #define _LTTNG_RING_BUFFER_CONFIG_H | |
12 | ||
a6352fd4 | 13 | #include <errno.h> |
4318ae1b | 14 | #include "lttng/ust-tracer.h" |
b728d87e MD |
15 | #include <stdint.h> |
16 | #include <stddef.h> | |
17 | #include <urcu/arch.h> | |
2e707419 | 18 | #include <string.h> |
4318ae1b | 19 | #include "lttng/align.h" |
a8909ba5 | 20 | #include <lttng/ust-compiler.h> |
a6352fd4 | 21 | |
4cfec15c | 22 | struct lttng_ust_lib_ring_buffer; |
a6352fd4 | 23 | struct channel; |
4cfec15c MD |
24 | struct lttng_ust_lib_ring_buffer_config; |
25 | struct lttng_ust_lib_ring_buffer_ctx; | |
5a821cd6 | 26 | struct lttng_ust_shm_handle; |
a6352fd4 MD |
27 | |
28 | /* | |
29 | * Ring buffer client callbacks. Only used by slow path, never on fast path. | |
30 | * For the fast path, record_header_size(), ring_buffer_clock_read() should be | |
31 | * provided as inline functions too. These may simply return 0 if not used by | |
32 | * the client. | |
33 | */ | |
4cfec15c | 34 | struct lttng_ust_lib_ring_buffer_client_cb { |
a6352fd4 MD |
35 | /* Mandatory callbacks */ |
36 | ||
37 | /* A static inline version is also required for fast path */ | |
2fed87ae | 38 | uint64_t (*ring_buffer_clock_read) (struct channel *chan); |
4cfec15c | 39 | size_t (*record_header_size) (const struct lttng_ust_lib_ring_buffer_config *config, |
a6352fd4 MD |
40 | struct channel *chan, size_t offset, |
41 | size_t *pre_header_padding, | |
e56bb47c MD |
42 | struct lttng_ust_lib_ring_buffer_ctx *ctx, |
43 | void *client_ctx); | |
a6352fd4 MD |
44 | |
45 | /* Slow path only, at subbuffer switch */ | |
46 | size_t (*subbuffer_header_size) (void); | |
2fed87ae | 47 | void (*buffer_begin) (struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc, |
1d498196 | 48 | unsigned int subbuf_idx, |
38fae1d3 | 49 | struct lttng_ust_shm_handle *handle); |
2fed87ae | 50 | void (*buffer_end) (struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc, |
1d498196 | 51 | unsigned int subbuf_idx, unsigned long data_size, |
38fae1d3 | 52 | struct lttng_ust_shm_handle *handle); |
a6352fd4 MD |
53 | |
54 | /* Optional callbacks (can be set to NULL) */ | |
55 | ||
56 | /* Called at buffer creation/finalize */ | |
4cfec15c | 57 | int (*buffer_create) (struct lttng_ust_lib_ring_buffer *buf, void *priv, |
1d498196 | 58 | int cpu, const char *name, |
38fae1d3 | 59 | struct lttng_ust_shm_handle *handle); |
a6352fd4 MD |
60 | /* |
61 | * Clients should guarantee that no new reader handle can be opened | |
62 | * after finalize. | |
63 | */ | |
4cfec15c | 64 | void (*buffer_finalize) (struct lttng_ust_lib_ring_buffer *buf, |
1d498196 | 65 | void *priv, int cpu, |
38fae1d3 | 66 | struct lttng_ust_shm_handle *handle); |
a6352fd4 MD |
67 | |
68 | /* | |
69 | * Extract header length, payload length and timestamp from event | |
70 | * record. Used by buffer iterators. Timestamp is only used by channel | |
71 | * iterator. | |
72 | */ | |
4cfec15c MD |
73 | void (*record_get) (const struct lttng_ust_lib_ring_buffer_config *config, |
74 | struct channel *chan, struct lttng_ust_lib_ring_buffer *buf, | |
a6352fd4 | 75 | size_t offset, size_t *header_len, |
2fed87ae | 76 | size_t *payload_len, uint64_t *timestamp, |
38fae1d3 | 77 | struct lttng_ust_shm_handle *handle); |
a9ff648c MD |
78 | /* |
79 | * Offset and size of content size field in client. | |
80 | */ | |
81 | void (*content_size_field) (const struct lttng_ust_lib_ring_buffer_config *config, | |
82 | size_t *offset, size_t *length); | |
83 | void (*packet_size_field) (const struct lttng_ust_lib_ring_buffer_config *config, | |
84 | size_t *offset, size_t *length); | |
a6352fd4 MD |
85 | }; |
86 | ||
87 | /* | |
88 | * Ring buffer instance configuration. | |
89 | * | |
90 | * Declare as "static const" within the client object to ensure the inline fast | |
91 | * paths can be optimized. | |
92 | * | |
93 | * alloc/sync pairs: | |
94 | * | |
95 | * RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_PER_CPU : | |
96 | * Per-cpu buffers with per-cpu synchronization. Tracing must be performed | |
97 | * with preemption disabled (lib_ring_buffer_get_cpu() and | |
98 | * lib_ring_buffer_put_cpu()). | |
99 | * | |
100 | * RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_GLOBAL : | |
101 | * Per-cpu buffer with global synchronization. Tracing can be performed with | |
102 | * preemption enabled, statistically stays on the local buffers. | |
103 | * | |
104 | * RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_PER_CPU : | |
105 | * Should only be used for buffers belonging to a single thread or protected | |
106 | * by mutual exclusion by the client. Note that periodical sub-buffer switch | |
107 | * should be disabled in this kind of configuration. | |
108 | * | |
109 | * RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_GLOBAL : | |
110 | * Global shared buffer with global synchronization. | |
111 | * | |
112 | * wakeup: | |
113 | * | |
114 | * RING_BUFFER_WAKEUP_BY_TIMER uses per-cpu deferrable timers to poll the | |
115 | * buffers and wake up readers if data is ready. Mainly useful for tracers which | |
116 | * don't want to call into the wakeup code on the tracing path. Use in | |
117 | * combination with "read_timer_interval" channel_create() argument. | |
118 | * | |
119 | * RING_BUFFER_WAKEUP_BY_WRITER directly wakes up readers when a subbuffer is | |
120 | * ready to read. Lower latencies before the reader is woken up. Mainly suitable | |
121 | * for drivers. | |
122 | * | |
123 | * RING_BUFFER_WAKEUP_NONE does not perform any wakeup whatsoever. The client | |
124 | * has the responsibility to perform wakeups. | |
125 | */ | |
82b9bde8 | 126 | #define LTTNG_UST_RING_BUFFER_CONFIG_PADDING 20 |
46d52200 ZT |
127 | |
128 | enum lttng_ust_lib_ring_buffer_alloc_types { | |
129 | RING_BUFFER_ALLOC_PER_CPU, | |
130 | RING_BUFFER_ALLOC_GLOBAL, | |
131 | }; | |
132 | ||
133 | enum lttng_ust_lib_ring_buffer_sync_types { | |
134 | RING_BUFFER_SYNC_PER_CPU, /* Wait-free */ | |
135 | RING_BUFFER_SYNC_GLOBAL, /* Lock-free */ | |
136 | }; | |
137 | ||
138 | enum lttng_ust_lib_ring_buffer_mode_types { | |
a9ff648c MD |
139 | RING_BUFFER_OVERWRITE = 0, /* Overwrite when buffer full */ |
140 | RING_BUFFER_DISCARD = 1, /* Discard when buffer full */ | |
46d52200 ZT |
141 | }; |
142 | ||
143 | enum lttng_ust_lib_ring_buffer_output_types { | |
144 | RING_BUFFER_SPLICE, | |
145 | RING_BUFFER_MMAP, | |
146 | RING_BUFFER_READ, /* TODO */ | |
147 | RING_BUFFER_ITERATOR, | |
148 | RING_BUFFER_NONE, | |
149 | }; | |
150 | ||
151 | enum lttng_ust_lib_ring_buffer_backend_types { | |
152 | RING_BUFFER_PAGE, | |
153 | RING_BUFFER_VMAP, /* TODO */ | |
154 | RING_BUFFER_STATIC, /* TODO */ | |
155 | }; | |
156 | ||
157 | enum lttng_ust_lib_ring_buffer_oops_types { | |
158 | RING_BUFFER_NO_OOPS_CONSISTENCY, | |
159 | RING_BUFFER_OOPS_CONSISTENCY, | |
160 | }; | |
161 | ||
162 | enum lttng_ust_lib_ring_buffer_ipi_types { | |
163 | RING_BUFFER_IPI_BARRIER, | |
164 | RING_BUFFER_NO_IPI_BARRIER, | |
165 | }; | |
166 | ||
167 | enum lttng_ust_lib_ring_buffer_wakeup_types { | |
168 | RING_BUFFER_WAKEUP_BY_TIMER, /* wake up performed by timer */ | |
169 | RING_BUFFER_WAKEUP_BY_WRITER, /* | |
170 | * writer wakes up reader, | |
171 | * not lock-free | |
172 | * (takes spinlock). | |
173 | */ | |
174 | }; | |
175 | ||
4cfec15c | 176 | struct lttng_ust_lib_ring_buffer_config { |
46d52200 ZT |
177 | enum lttng_ust_lib_ring_buffer_alloc_types alloc; |
178 | enum lttng_ust_lib_ring_buffer_sync_types sync; | |
179 | enum lttng_ust_lib_ring_buffer_mode_types mode; | |
180 | enum lttng_ust_lib_ring_buffer_output_types output; | |
181 | enum lttng_ust_lib_ring_buffer_backend_types backend; | |
182 | enum lttng_ust_lib_ring_buffer_oops_types oops; | |
183 | enum lttng_ust_lib_ring_buffer_ipi_types ipi; | |
184 | enum lttng_ust_lib_ring_buffer_wakeup_types wakeup; | |
a6352fd4 MD |
185 | /* |
186 | * tsc_bits: timestamp bits saved at each record. | |
187 | * 0 and 64 disable the timestamp compression scheme. | |
188 | */ | |
189 | unsigned int tsc_bits; | |
4cfec15c | 190 | struct lttng_ust_lib_ring_buffer_client_cb cb; |
c1fca457 MD |
191 | /* |
192 | * client_type is used by the consumer process (which is in a | |
193 | * different address space) to lookup the appropriate client | |
194 | * callbacks and update the cb pointers. | |
195 | */ | |
196 | int client_type; | |
82b9bde8 JD |
197 | int _unused1; |
198 | const struct lttng_ust_lib_ring_buffer_client_cb *cb_ptr; | |
2e707419 | 199 | char padding[LTTNG_UST_RING_BUFFER_CONFIG_PADDING]; |
a6352fd4 MD |
200 | }; |
201 | ||
202 | /* | |
203 | * ring buffer context | |
204 | * | |
205 | * Context passed to lib_ring_buffer_reserve(), lib_ring_buffer_commit(), | |
206 | * lib_ring_buffer_try_discard_reserve(), lib_ring_buffer_align_ctx() and | |
207 | * lib_ring_buffer_write(). | |
180901e6 MD |
208 | * |
209 | * IMPORTANT: this structure is part of the ABI between the probe and | |
210 | * UST. Fields need to be only added at the end, never reordered, never | |
211 | * removed. | |
a6352fd4 | 212 | */ |
96f85541 | 213 | #define LTTNG_UST_RING_BUFFER_CTX_PADDING \ |
53569322 | 214 | (24 - sizeof(int) - sizeof(void *) - sizeof(void *)) |
4cfec15c | 215 | struct lttng_ust_lib_ring_buffer_ctx { |
a6352fd4 MD |
216 | /* input received by lib_ring_buffer_reserve(), saved here. */ |
217 | struct channel *chan; /* channel */ | |
218 | void *priv; /* client private data */ | |
38fae1d3 | 219 | struct lttng_ust_shm_handle *handle; /* shared-memory handle */ |
a6352fd4 MD |
220 | size_t data_size; /* size of payload */ |
221 | int largest_align; /* | |
222 | * alignment of the largest element | |
223 | * in the payload | |
224 | */ | |
225 | int cpu; /* processor id */ | |
226 | ||
227 | /* output from lib_ring_buffer_reserve() */ | |
4cfec15c | 228 | struct lttng_ust_lib_ring_buffer *buf; /* |
a6352fd4 MD |
229 | * buffer corresponding to processor id |
230 | * for this channel | |
231 | */ | |
232 | size_t slot_size; /* size of the reserved slot */ | |
233 | unsigned long buf_offset; /* offset following the record header */ | |
234 | unsigned long pre_offset; /* | |
235 | * Initial offset position _before_ | |
236 | * the record is written. Positioned | |
237 | * prior to record header alignment | |
238 | * padding. | |
239 | */ | |
2fed87ae | 240 | uint64_t tsc; /* time-stamp counter value */ |
a6352fd4 | 241 | unsigned int rflags; /* reservation flags */ |
82cd0cfd MD |
242 | /* |
243 | * The field ctx_len is the length of struct | |
244 | * lttng_ust_lib_ring_buffer_ctx as known by the user of | |
245 | * lib_ring_buffer_ctx_init. | |
246 | */ | |
247 | unsigned int ctx_len; | |
96f85541 | 248 | void *ip; /* caller ip address */ |
53569322 | 249 | void *priv2; /* 2nd priv data */ |
96f85541 | 250 | char padding2[LTTNG_UST_RING_BUFFER_CTX_PADDING]; |
82cd0cfd MD |
251 | /* |
252 | * This is the end of the initial fields expected by the original ABI | |
253 | * between probes and UST. Only the fields above can be used if | |
254 | * ctx_len is 0. Use the value of ctx_len to find out which of the | |
255 | * following fields may be used. | |
256 | */ | |
a3492932 | 257 | struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages; |
a6352fd4 MD |
258 | }; |
259 | ||
260 | /** | |
261 | * lib_ring_buffer_ctx_init - initialize ring buffer context | |
262 | * @ctx: ring buffer context to initialize | |
263 | * @chan: channel | |
264 | * @priv: client private data | |
265 | * @data_size: size of record data payload | |
266 | * @largest_align: largest alignment within data payload types | |
267 | * @cpu: processor id | |
268 | */ | |
a8909ba5 PW |
269 | static inline lttng_ust_notrace |
270 | void lib_ring_buffer_ctx_init(struct lttng_ust_lib_ring_buffer_ctx *ctx, | |
271 | struct channel *chan, void *priv, | |
272 | size_t data_size, int largest_align, | |
53569322 MD |
273 | int cpu, struct lttng_ust_shm_handle *handle, |
274 | void *priv2); | |
a6352fd4 | 275 | static inline |
4cfec15c | 276 | void lib_ring_buffer_ctx_init(struct lttng_ust_lib_ring_buffer_ctx *ctx, |
a6352fd4 MD |
277 | struct channel *chan, void *priv, |
278 | size_t data_size, int largest_align, | |
53569322 MD |
279 | int cpu, struct lttng_ust_shm_handle *handle, |
280 | void *priv2) | |
a6352fd4 MD |
281 | { |
282 | ctx->chan = chan; | |
283 | ctx->priv = priv; | |
284 | ctx->data_size = data_size; | |
285 | ctx->largest_align = largest_align; | |
286 | ctx->cpu = cpu; | |
287 | ctx->rflags = 0; | |
1d498196 | 288 | ctx->handle = handle; |
82cd0cfd | 289 | ctx->ctx_len = sizeof(struct lttng_ust_lib_ring_buffer_ctx); |
96f85541 | 290 | ctx->ip = 0; |
53569322 | 291 | ctx->priv2 = priv2; |
96f85541 | 292 | memset(ctx->padding2, 0, LTTNG_UST_RING_BUFFER_CTX_PADDING); |
a6352fd4 MD |
293 | } |
294 | ||
295 | /* | |
296 | * Reservation flags. | |
297 | * | |
298 | * RING_BUFFER_RFLAG_FULL_TSC | |
299 | * | |
300 | * This flag is passed to record_header_size() and to the primitive used to | |
301 | * write the record header. It indicates that the full 64-bit time value is | |
302 | * needed in the record header. If this flag is not set, the record header needs | |
303 | * only to contain "tsc_bits" bit of time value. | |
304 | * | |
305 | * Reservation flags can be added by the client, starting from | |
306 | * "(RING_BUFFER_FLAGS_END << 0)". It can be used to pass information from | |
307 | * record_header_size() to lib_ring_buffer_write_record_header(). | |
308 | */ | |
309 | #define RING_BUFFER_RFLAG_FULL_TSC (1U << 0) | |
310 | #define RING_BUFFER_RFLAG_END (1U << 1) | |
311 | ||
312 | /* | |
313 | * We need to define RING_BUFFER_ALIGN_ATTR so it is known early at | |
314 | * compile-time. We have to duplicate the "config->align" information and the | |
315 | * definition here because config->align is used both in the slow and fast | |
316 | * paths, but RING_BUFFER_ALIGN_ATTR is only available for the client code. | |
317 | */ | |
318 | #ifdef RING_BUFFER_ALIGN | |
319 | ||
320 | # define RING_BUFFER_ALIGN_ATTR /* Default arch alignment */ | |
321 | ||
322 | /* | |
323 | * Calculate the offset needed to align the type. | |
324 | * size_of_type must be non-zero. | |
325 | */ | |
a8909ba5 PW |
326 | static inline lttng_ust_notrace |
327 | unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type); | |
a6352fd4 MD |
328 | static inline |
329 | unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type) | |
330 | { | |
b72687b8 | 331 | return lttng_ust_offset_align(align_drift, size_of_type); |
a6352fd4 MD |
332 | } |
333 | ||
334 | #else | |
335 | ||
336 | # define RING_BUFFER_ALIGN_ATTR __attribute__((packed)) | |
337 | ||
338 | /* | |
339 | * Calculate the offset needed to align the type. | |
340 | * size_of_type must be non-zero. | |
341 | */ | |
a8909ba5 PW |
342 | static inline lttng_ust_notrace |
343 | unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type); | |
a6352fd4 MD |
344 | static inline |
345 | unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type) | |
346 | { | |
347 | return 0; | |
348 | } | |
349 | ||
350 | #endif | |
351 | ||
352 | /** | |
353 | * lib_ring_buffer_align_ctx - Align context offset on "alignment" | |
354 | * @ctx: ring buffer context. | |
355 | */ | |
a8909ba5 PW |
356 | static inline lttng_ust_notrace |
357 | void lib_ring_buffer_align_ctx(struct lttng_ust_lib_ring_buffer_ctx *ctx, | |
358 | size_t alignment); | |
a6352fd4 | 359 | static inline |
4cfec15c | 360 | void lib_ring_buffer_align_ctx(struct lttng_ust_lib_ring_buffer_ctx *ctx, |
a6352fd4 MD |
361 | size_t alignment) |
362 | { | |
363 | ctx->buf_offset += lib_ring_buffer_align(ctx->buf_offset, | |
364 | alignment); | |
365 | } | |
366 | ||
367 | /* | |
368 | * lib_ring_buffer_check_config() returns 0 on success. | |
369 | * Used internally to check for valid configurations at channel creation. | |
370 | */ | |
a8909ba5 PW |
371 | static inline lttng_ust_notrace |
372 | int lib_ring_buffer_check_config(const struct lttng_ust_lib_ring_buffer_config *config, | |
373 | unsigned int switch_timer_interval, | |
374 | unsigned int read_timer_interval); | |
a6352fd4 | 375 | static inline |
4cfec15c | 376 | int lib_ring_buffer_check_config(const struct lttng_ust_lib_ring_buffer_config *config, |
a6352fd4 MD |
377 | unsigned int switch_timer_interval, |
378 | unsigned int read_timer_interval) | |
379 | { | |
380 | if (config->alloc == RING_BUFFER_ALLOC_GLOBAL | |
381 | && config->sync == RING_BUFFER_SYNC_PER_CPU | |
382 | && switch_timer_interval) | |
383 | return -EINVAL; | |
384 | return 0; | |
385 | } | |
386 | ||
e92f3e28 | 387 | #endif /* _LTTNG_RING_BUFFER_CONFIG_H */ |