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a6352fd4 MD |
1 | #ifndef _LINUX_RING_BUFFER_CONFIG_H |
2 | #define _LINUX_RING_BUFFER_CONFIG_H | |
3 | ||
4 | /* | |
5 | * linux/ringbuffer/config.h | |
6 | * | |
7 | * Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
8 | * | |
9 | * Ring buffer configuration header. Note: after declaring the standard inline | |
10 | * functions, clients should also include linux/ringbuffer/api.h. | |
11 | * | |
12 | * Dual LGPL v2.1/GPL v2 license. | |
13 | */ | |
14 | ||
15 | #include <errno.h> | |
4318ae1b MD |
16 | #include "lttng/ust-tracer.h" |
17 | #include "lttng/usterr-signal-safe.h" | |
18 | #include "lttng/kcompat/kcompat.h" | |
19 | #include "lttng/align.h" | |
a6352fd4 | 20 | |
4cfec15c | 21 | struct lttng_ust_lib_ring_buffer; |
a6352fd4 | 22 | struct channel; |
4cfec15c MD |
23 | struct lttng_ust_lib_ring_buffer_config; |
24 | struct lttng_ust_lib_ring_buffer_ctx; | |
38fae1d3 | 25 | struct lttng_ust_shm_handle *handle; |
a6352fd4 MD |
26 | |
27 | /* | |
28 | * Ring buffer client callbacks. Only used by slow path, never on fast path. | |
29 | * For the fast path, record_header_size(), ring_buffer_clock_read() should be | |
30 | * provided as inline functions too. These may simply return 0 if not used by | |
31 | * the client. | |
32 | */ | |
4cfec15c | 33 | struct lttng_ust_lib_ring_buffer_client_cb { |
a6352fd4 MD |
34 | /* Mandatory callbacks */ |
35 | ||
36 | /* A static inline version is also required for fast path */ | |
37 | u64 (*ring_buffer_clock_read) (struct channel *chan); | |
4cfec15c | 38 | size_t (*record_header_size) (const struct lttng_ust_lib_ring_buffer_config *config, |
a6352fd4 MD |
39 | struct channel *chan, size_t offset, |
40 | size_t *pre_header_padding, | |
4cfec15c | 41 | struct lttng_ust_lib_ring_buffer_ctx *ctx); |
a6352fd4 MD |
42 | |
43 | /* Slow path only, at subbuffer switch */ | |
44 | size_t (*subbuffer_header_size) (void); | |
4cfec15c | 45 | void (*buffer_begin) (struct lttng_ust_lib_ring_buffer *buf, u64 tsc, |
1d498196 | 46 | unsigned int subbuf_idx, |
38fae1d3 | 47 | struct lttng_ust_shm_handle *handle); |
4cfec15c | 48 | void (*buffer_end) (struct lttng_ust_lib_ring_buffer *buf, u64 tsc, |
1d498196 | 49 | unsigned int subbuf_idx, unsigned long data_size, |
38fae1d3 | 50 | struct lttng_ust_shm_handle *handle); |
a6352fd4 MD |
51 | |
52 | /* Optional callbacks (can be set to NULL) */ | |
53 | ||
54 | /* Called at buffer creation/finalize */ | |
4cfec15c | 55 | int (*buffer_create) (struct lttng_ust_lib_ring_buffer *buf, void *priv, |
1d498196 | 56 | int cpu, const char *name, |
38fae1d3 | 57 | struct lttng_ust_shm_handle *handle); |
a6352fd4 MD |
58 | /* |
59 | * Clients should guarantee that no new reader handle can be opened | |
60 | * after finalize. | |
61 | */ | |
4cfec15c | 62 | void (*buffer_finalize) (struct lttng_ust_lib_ring_buffer *buf, |
1d498196 | 63 | void *priv, int cpu, |
38fae1d3 | 64 | struct lttng_ust_shm_handle *handle); |
a6352fd4 MD |
65 | |
66 | /* | |
67 | * Extract header length, payload length and timestamp from event | |
68 | * record. Used by buffer iterators. Timestamp is only used by channel | |
69 | * iterator. | |
70 | */ | |
4cfec15c MD |
71 | void (*record_get) (const struct lttng_ust_lib_ring_buffer_config *config, |
72 | struct channel *chan, struct lttng_ust_lib_ring_buffer *buf, | |
a6352fd4 | 73 | size_t offset, size_t *header_len, |
1d498196 | 74 | size_t *payload_len, u64 *timestamp, |
38fae1d3 | 75 | struct lttng_ust_shm_handle *handle); |
a6352fd4 MD |
76 | }; |
77 | ||
78 | /* | |
79 | * Ring buffer instance configuration. | |
80 | * | |
81 | * Declare as "static const" within the client object to ensure the inline fast | |
82 | * paths can be optimized. | |
83 | * | |
84 | * alloc/sync pairs: | |
85 | * | |
86 | * RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_PER_CPU : | |
87 | * Per-cpu buffers with per-cpu synchronization. Tracing must be performed | |
88 | * with preemption disabled (lib_ring_buffer_get_cpu() and | |
89 | * lib_ring_buffer_put_cpu()). | |
90 | * | |
91 | * RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_GLOBAL : | |
92 | * Per-cpu buffer with global synchronization. Tracing can be performed with | |
93 | * preemption enabled, statistically stays on the local buffers. | |
94 | * | |
95 | * RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_PER_CPU : | |
96 | * Should only be used for buffers belonging to a single thread or protected | |
97 | * by mutual exclusion by the client. Note that periodical sub-buffer switch | |
98 | * should be disabled in this kind of configuration. | |
99 | * | |
100 | * RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_GLOBAL : | |
101 | * Global shared buffer with global synchronization. | |
102 | * | |
103 | * wakeup: | |
104 | * | |
105 | * RING_BUFFER_WAKEUP_BY_TIMER uses per-cpu deferrable timers to poll the | |
106 | * buffers and wake up readers if data is ready. Mainly useful for tracers which | |
107 | * don't want to call into the wakeup code on the tracing path. Use in | |
108 | * combination with "read_timer_interval" channel_create() argument. | |
109 | * | |
110 | * RING_BUFFER_WAKEUP_BY_WRITER directly wakes up readers when a subbuffer is | |
111 | * ready to read. Lower latencies before the reader is woken up. Mainly suitable | |
112 | * for drivers. | |
113 | * | |
114 | * RING_BUFFER_WAKEUP_NONE does not perform any wakeup whatsoever. The client | |
115 | * has the responsibility to perform wakeups. | |
116 | */ | |
4cfec15c | 117 | struct lttng_ust_lib_ring_buffer_config { |
a6352fd4 MD |
118 | enum { |
119 | RING_BUFFER_ALLOC_PER_CPU, | |
120 | RING_BUFFER_ALLOC_GLOBAL, | |
121 | } alloc; | |
122 | enum { | |
123 | RING_BUFFER_SYNC_PER_CPU, /* Wait-free */ | |
124 | RING_BUFFER_SYNC_GLOBAL, /* Lock-free */ | |
125 | } sync; | |
126 | enum { | |
127 | RING_BUFFER_OVERWRITE, /* Overwrite when buffer full */ | |
128 | RING_BUFFER_DISCARD, /* Discard when buffer full */ | |
129 | } mode; | |
130 | enum { | |
131 | RING_BUFFER_SPLICE, | |
132 | RING_BUFFER_MMAP, | |
133 | RING_BUFFER_READ, /* TODO */ | |
134 | RING_BUFFER_ITERATOR, | |
135 | RING_BUFFER_NONE, | |
136 | } output; | |
137 | enum { | |
138 | RING_BUFFER_PAGE, | |
139 | RING_BUFFER_VMAP, /* TODO */ | |
140 | RING_BUFFER_STATIC, /* TODO */ | |
141 | } backend; | |
142 | enum { | |
143 | RING_BUFFER_NO_OOPS_CONSISTENCY, | |
144 | RING_BUFFER_OOPS_CONSISTENCY, | |
145 | } oops; | |
146 | enum { | |
147 | RING_BUFFER_IPI_BARRIER, | |
148 | RING_BUFFER_NO_IPI_BARRIER, | |
149 | } ipi; | |
150 | enum { | |
151 | RING_BUFFER_WAKEUP_BY_TIMER, /* wake up performed by timer */ | |
152 | RING_BUFFER_WAKEUP_BY_WRITER, /* | |
153 | * writer wakes up reader, | |
154 | * not lock-free | |
155 | * (takes spinlock). | |
156 | */ | |
157 | } wakeup; | |
158 | /* | |
159 | * tsc_bits: timestamp bits saved at each record. | |
160 | * 0 and 64 disable the timestamp compression scheme. | |
161 | */ | |
162 | unsigned int tsc_bits; | |
4cfec15c | 163 | struct lttng_ust_lib_ring_buffer_client_cb cb; |
a6352fd4 MD |
164 | }; |
165 | ||
166 | /* | |
167 | * ring buffer context | |
168 | * | |
169 | * Context passed to lib_ring_buffer_reserve(), lib_ring_buffer_commit(), | |
170 | * lib_ring_buffer_try_discard_reserve(), lib_ring_buffer_align_ctx() and | |
171 | * lib_ring_buffer_write(). | |
172 | */ | |
4cfec15c | 173 | struct lttng_ust_lib_ring_buffer_ctx { |
a6352fd4 MD |
174 | /* input received by lib_ring_buffer_reserve(), saved here. */ |
175 | struct channel *chan; /* channel */ | |
176 | void *priv; /* client private data */ | |
38fae1d3 | 177 | struct lttng_ust_shm_handle *handle; /* shared-memory handle */ |
a6352fd4 MD |
178 | size_t data_size; /* size of payload */ |
179 | int largest_align; /* | |
180 | * alignment of the largest element | |
181 | * in the payload | |
182 | */ | |
183 | int cpu; /* processor id */ | |
184 | ||
185 | /* output from lib_ring_buffer_reserve() */ | |
4cfec15c | 186 | struct lttng_ust_lib_ring_buffer *buf; /* |
a6352fd4 MD |
187 | * buffer corresponding to processor id |
188 | * for this channel | |
189 | */ | |
190 | size_t slot_size; /* size of the reserved slot */ | |
191 | unsigned long buf_offset; /* offset following the record header */ | |
192 | unsigned long pre_offset; /* | |
193 | * Initial offset position _before_ | |
194 | * the record is written. Positioned | |
195 | * prior to record header alignment | |
196 | * padding. | |
197 | */ | |
198 | u64 tsc; /* time-stamp counter value */ | |
199 | unsigned int rflags; /* reservation flags */ | |
200 | }; | |
201 | ||
202 | /** | |
203 | * lib_ring_buffer_ctx_init - initialize ring buffer context | |
204 | * @ctx: ring buffer context to initialize | |
205 | * @chan: channel | |
206 | * @priv: client private data | |
207 | * @data_size: size of record data payload | |
208 | * @largest_align: largest alignment within data payload types | |
209 | * @cpu: processor id | |
210 | */ | |
211 | static inline | |
4cfec15c | 212 | void lib_ring_buffer_ctx_init(struct lttng_ust_lib_ring_buffer_ctx *ctx, |
a6352fd4 MD |
213 | struct channel *chan, void *priv, |
214 | size_t data_size, int largest_align, | |
38fae1d3 | 215 | int cpu, struct lttng_ust_shm_handle *handle) |
a6352fd4 MD |
216 | { |
217 | ctx->chan = chan; | |
218 | ctx->priv = priv; | |
219 | ctx->data_size = data_size; | |
220 | ctx->largest_align = largest_align; | |
221 | ctx->cpu = cpu; | |
222 | ctx->rflags = 0; | |
1d498196 | 223 | ctx->handle = handle; |
a6352fd4 MD |
224 | } |
225 | ||
226 | /* | |
227 | * Reservation flags. | |
228 | * | |
229 | * RING_BUFFER_RFLAG_FULL_TSC | |
230 | * | |
231 | * This flag is passed to record_header_size() and to the primitive used to | |
232 | * write the record header. It indicates that the full 64-bit time value is | |
233 | * needed in the record header. If this flag is not set, the record header needs | |
234 | * only to contain "tsc_bits" bit of time value. | |
235 | * | |
236 | * Reservation flags can be added by the client, starting from | |
237 | * "(RING_BUFFER_FLAGS_END << 0)". It can be used to pass information from | |
238 | * record_header_size() to lib_ring_buffer_write_record_header(). | |
239 | */ | |
240 | #define RING_BUFFER_RFLAG_FULL_TSC (1U << 0) | |
241 | #define RING_BUFFER_RFLAG_END (1U << 1) | |
242 | ||
243 | /* | |
244 | * We need to define RING_BUFFER_ALIGN_ATTR so it is known early at | |
245 | * compile-time. We have to duplicate the "config->align" information and the | |
246 | * definition here because config->align is used both in the slow and fast | |
247 | * paths, but RING_BUFFER_ALIGN_ATTR is only available for the client code. | |
248 | */ | |
249 | #ifdef RING_BUFFER_ALIGN | |
250 | ||
251 | # define RING_BUFFER_ALIGN_ATTR /* Default arch alignment */ | |
252 | ||
253 | /* | |
254 | * Calculate the offset needed to align the type. | |
255 | * size_of_type must be non-zero. | |
256 | */ | |
257 | static inline | |
258 | unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type) | |
259 | { | |
260 | return offset_align(align_drift, size_of_type); | |
261 | } | |
262 | ||
263 | #else | |
264 | ||
265 | # define RING_BUFFER_ALIGN_ATTR __attribute__((packed)) | |
266 | ||
267 | /* | |
268 | * Calculate the offset needed to align the type. | |
269 | * size_of_type must be non-zero. | |
270 | */ | |
271 | static inline | |
272 | unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type) | |
273 | { | |
274 | return 0; | |
275 | } | |
276 | ||
277 | #endif | |
278 | ||
279 | /** | |
280 | * lib_ring_buffer_align_ctx - Align context offset on "alignment" | |
281 | * @ctx: ring buffer context. | |
282 | */ | |
283 | static inline | |
4cfec15c | 284 | void lib_ring_buffer_align_ctx(struct lttng_ust_lib_ring_buffer_ctx *ctx, |
a6352fd4 MD |
285 | size_t alignment) |
286 | { | |
287 | ctx->buf_offset += lib_ring_buffer_align(ctx->buf_offset, | |
288 | alignment); | |
289 | } | |
290 | ||
291 | /* | |
292 | * lib_ring_buffer_check_config() returns 0 on success. | |
293 | * Used internally to check for valid configurations at channel creation. | |
294 | */ | |
295 | static inline | |
4cfec15c | 296 | int lib_ring_buffer_check_config(const struct lttng_ust_lib_ring_buffer_config *config, |
a6352fd4 MD |
297 | unsigned int switch_timer_interval, |
298 | unsigned int read_timer_interval) | |
299 | { | |
300 | if (config->alloc == RING_BUFFER_ALLOC_GLOBAL | |
301 | && config->sync == RING_BUFFER_SYNC_PER_CPU | |
302 | && switch_timer_interval) | |
303 | return -EINVAL; | |
304 | return 0; | |
305 | } | |
306 | ||
4318ae1b | 307 | #include <lttng/vatomic.h> |
a6352fd4 MD |
308 | |
309 | #endif /* _LINUX_RING_BUFFER_CONFIG_H */ |