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b7cdc182 | 1 | /* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only) |
9f36eaed | 2 | * |
24591303 | 3 | * ringbuffer/config.h |
f3bc08c5 MD |
4 | * |
5 | * Ring buffer configuration header. Note: after declaring the standard inline | |
6 | * functions, clients should also include linux/ringbuffer/api.h. | |
7 | * | |
886d51a3 | 8 | * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
f3bc08c5 MD |
9 | */ |
10 | ||
9f36eaed MJ |
11 | #ifndef _LIB_RING_BUFFER_CONFIG_H |
12 | #define _LIB_RING_BUFFER_CONFIG_H | |
13 | ||
f3bc08c5 MD |
14 | #include <linux/types.h> |
15 | #include <linux/percpu.h> | |
a071f25d | 16 | #include <lttng/align.h> |
2df37e95 | 17 | #include <lttng/tracer-core.h> |
f3bc08c5 | 18 | |
a2a1b5ab | 19 | struct lttng_kernel_ring_buffer; |
4071a628 | 20 | struct lttng_kernel_ring_buffer_channel; |
a2a1b5ab | 21 | struct lttng_kernel_ring_buffer_config; |
e27e4381 | 22 | struct lttng_kernel_ring_buffer_ctx; |
c7d9db61 | 23 | struct lttng_kernel_ring_buffer_ctx_private; |
f3bc08c5 MD |
24 | |
25 | /* | |
26 | * Ring buffer client callbacks. Only used by slow path, never on fast path. | |
27 | * For the fast path, record_header_size(), ring_buffer_clock_read() should be | |
28 | * provided as inline functions too. These may simply return 0 if not used by | |
29 | * the client. | |
30 | */ | |
a2a1b5ab | 31 | struct lttng_kernel_ring_buffer_client_cb { |
f3bc08c5 MD |
32 | /* Mandatory callbacks */ |
33 | ||
34 | /* A static inline version is also required for fast path */ | |
4071a628 | 35 | u64 (*ring_buffer_clock_read) (struct lttng_kernel_ring_buffer_channel *chan); |
a2a1b5ab | 36 | size_t (*record_header_size) (const struct lttng_kernel_ring_buffer_config *config, |
4071a628 | 37 | struct lttng_kernel_ring_buffer_channel *chan, size_t offset, |
f3bc08c5 | 38 | size_t *pre_header_padding, |
e27e4381 | 39 | struct lttng_kernel_ring_buffer_ctx *ctx, |
cc62f29e | 40 | void *client_ctx); |
f3bc08c5 MD |
41 | |
42 | /* Slow path only, at subbuffer switch */ | |
43 | size_t (*subbuffer_header_size) (void); | |
a2a1b5ab | 44 | void (*buffer_begin) (struct lttng_kernel_ring_buffer *buf, u64 tsc, |
f3bc08c5 | 45 | unsigned int subbuf_idx); |
a2a1b5ab | 46 | void (*buffer_end) (struct lttng_kernel_ring_buffer *buf, u64 tsc, |
c0733f3f MD |
47 | unsigned int subbuf_idx, unsigned long data_size, |
48 | const struct lttng_kernel_ring_buffer_ctx *ctx); | |
f3bc08c5 MD |
49 | |
50 | /* Optional callbacks (can be set to NULL) */ | |
51 | ||
52 | /* Called at buffer creation/finalize */ | |
a2a1b5ab | 53 | int (*buffer_create) (struct lttng_kernel_ring_buffer *buf, void *priv, |
f3bc08c5 MD |
54 | int cpu, const char *name); |
55 | /* | |
56 | * Clients should guarantee that no new reader handle can be opened | |
57 | * after finalize. | |
58 | */ | |
a2a1b5ab | 59 | void (*buffer_finalize) (struct lttng_kernel_ring_buffer *buf, void *priv, int cpu); |
f3bc08c5 MD |
60 | |
61 | /* | |
62 | * Extract header length, payload length and timestamp from event | |
63 | * record. Used by buffer iterators. Timestamp is only used by channel | |
64 | * iterator. | |
65 | */ | |
a2a1b5ab MD |
66 | void (*record_get) (const struct lttng_kernel_ring_buffer_config *config, |
67 | struct lttng_kernel_ring_buffer_channel *chan, struct lttng_kernel_ring_buffer *buf, | |
f3bc08c5 MD |
68 | size_t offset, size_t *header_len, |
69 | size_t *payload_len, u64 *timestamp); | |
70 | }; | |
71 | ||
72 | /* | |
73 | * Ring buffer instance configuration. | |
74 | * | |
75 | * Declare as "static const" within the client object to ensure the inline fast | |
76 | * paths can be optimized. | |
77 | * | |
78 | * alloc/sync pairs: | |
79 | * | |
80 | * RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_PER_CPU : | |
81 | * Per-cpu buffers with per-cpu synchronization. Tracing must be performed | |
82 | * with preemption disabled (lib_ring_buffer_get_cpu() and | |
83 | * lib_ring_buffer_put_cpu()). | |
84 | * | |
85 | * RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_GLOBAL : | |
86 | * Per-cpu buffer with global synchronization. Tracing can be performed with | |
87 | * preemption enabled, statistically stays on the local buffers. | |
88 | * | |
89 | * RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_PER_CPU : | |
90 | * Should only be used for buffers belonging to a single thread or protected | |
91 | * by mutual exclusion by the client. Note that periodical sub-buffer switch | |
92 | * should be disabled in this kind of configuration. | |
93 | * | |
94 | * RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_GLOBAL : | |
95 | * Global shared buffer with global synchronization. | |
96 | * | |
97 | * wakeup: | |
98 | * | |
da9f3fb7 | 99 | * RING_BUFFER_WAKEUP_BY_TIMER uses per-cpu timers to poll the |
f3bc08c5 MD |
100 | * buffers and wake up readers if data is ready. Mainly useful for tracers which |
101 | * don't want to call into the wakeup code on the tracing path. Use in | |
102 | * combination with "read_timer_interval" channel_create() argument. | |
103 | * | |
104 | * RING_BUFFER_WAKEUP_BY_WRITER directly wakes up readers when a subbuffer is | |
105 | * ready to read. Lower latencies before the reader is woken up. Mainly suitable | |
fbd4d558 MD |
106 | * for drivers. Going through an "irq_work" allows triggering this type of wakeup |
107 | * even from NMI context: the wakeup will be slightly delayed until the next | |
108 | * interrupts are handled. | |
f3bc08c5 MD |
109 | * |
110 | * RING_BUFFER_WAKEUP_NONE does not perform any wakeup whatsoever. The client | |
111 | * has the responsibility to perform wakeups. | |
112 | */ | |
a2a1b5ab | 113 | struct lttng_kernel_ring_buffer_config { |
f3bc08c5 MD |
114 | enum { |
115 | RING_BUFFER_ALLOC_PER_CPU, | |
116 | RING_BUFFER_ALLOC_GLOBAL, | |
117 | } alloc; | |
118 | enum { | |
119 | RING_BUFFER_SYNC_PER_CPU, /* Wait-free */ | |
120 | RING_BUFFER_SYNC_GLOBAL, /* Lock-free */ | |
121 | } sync; | |
122 | enum { | |
123 | RING_BUFFER_OVERWRITE, /* Overwrite when buffer full */ | |
124 | RING_BUFFER_DISCARD, /* Discard when buffer full */ | |
125 | } mode; | |
126 | enum { | |
127 | RING_BUFFER_SPLICE, | |
128 | RING_BUFFER_MMAP, | |
129 | RING_BUFFER_READ, /* TODO */ | |
130 | RING_BUFFER_ITERATOR, | |
131 | RING_BUFFER_NONE, | |
132 | } output; | |
133 | enum { | |
134 | RING_BUFFER_PAGE, | |
135 | RING_BUFFER_VMAP, /* TODO */ | |
136 | RING_BUFFER_STATIC, /* TODO */ | |
137 | } backend; | |
138 | enum { | |
139 | RING_BUFFER_NO_OOPS_CONSISTENCY, | |
140 | RING_BUFFER_OOPS_CONSISTENCY, | |
141 | } oops; | |
142 | enum { | |
143 | RING_BUFFER_IPI_BARRIER, | |
144 | RING_BUFFER_NO_IPI_BARRIER, | |
145 | } ipi; | |
146 | enum { | |
147 | RING_BUFFER_WAKEUP_BY_TIMER, /* wake up performed by timer */ | |
148 | RING_BUFFER_WAKEUP_BY_WRITER, /* | |
fbd4d558 MD |
149 | * writer wakes up reader through |
150 | * irq_work. | |
f3bc08c5 MD |
151 | */ |
152 | } wakeup; | |
153 | /* | |
154 | * tsc_bits: timestamp bits saved at each record. | |
155 | * 0 and 64 disable the timestamp compression scheme. | |
156 | */ | |
157 | unsigned int tsc_bits; | |
a2a1b5ab | 158 | struct lttng_kernel_ring_buffer_client_cb cb; |
f3bc08c5 MD |
159 | }; |
160 | ||
c7d9db61 MD |
161 | /* |
162 | * ring buffer private context | |
163 | * | |
164 | * Private context passed to lib_ring_buffer_reserve(), lib_ring_buffer_commit(), | |
165 | * lib_ring_buffer_try_discard_reserve(), lib_ring_buffer_align_ctx() and | |
166 | * lib_ring_buffer_write(). | |
167 | * | |
168 | * Get struct lttng_kernel_ring_buffer_ctx parent with container_of(). | |
169 | */ | |
170 | ||
171 | struct lttng_kernel_ring_buffer_ctx_private { | |
172 | /* input received by lib_ring_buffer_reserve(). */ | |
4071a628 | 173 | struct lttng_kernel_ring_buffer_channel *chan; /* ring buffer channel */ |
c7d9db61 MD |
174 | |
175 | /* output from lib_ring_buffer_reserve() */ | |
176 | int reserve_cpu; /* processor id updated by the reserve */ | |
177 | size_t slot_size; /* size of the reserved slot */ | |
178 | unsigned long buf_offset; /* offset following the record header */ | |
179 | unsigned long pre_offset; /* | |
180 | * Initial offset position _before_ | |
181 | * the record is written. Positioned | |
182 | * prior to record header alignment | |
183 | * padding. | |
184 | */ | |
185 | u64 tsc; /* time-stamp counter value */ | |
186 | unsigned int rflags; /* reservation flags */ | |
187 | ||
d2d15090 | 188 | struct lttng_kernel_ring_buffer *buf; /* |
c7d9db61 MD |
189 | * buffer corresponding to processor id |
190 | * for this channel | |
191 | */ | |
a2a1b5ab | 192 | struct lttng_kernel_ring_buffer_backend_pages *backend_pages; |
c0733f3f MD |
193 | |
194 | /* | |
195 | * Records lost counts are only loaded into these fields before | |
196 | * reserving the last bytes from the ring buffer. | |
197 | */ | |
198 | unsigned long records_lost_full; | |
199 | unsigned long records_lost_wrap; | |
200 | unsigned long records_lost_big; | |
c7d9db61 MD |
201 | }; |
202 | ||
f3bc08c5 MD |
203 | /* |
204 | * ring buffer context | |
205 | * | |
206 | * Context passed to lib_ring_buffer_reserve(), lib_ring_buffer_commit(), | |
207 | * lib_ring_buffer_try_discard_reserve(), lib_ring_buffer_align_ctx() and | |
208 | * lib_ring_buffer_write(). | |
209 | */ | |
e27e4381 | 210 | struct lttng_kernel_ring_buffer_ctx { |
c7d9db61 MD |
211 | /* Private ring buffer context, set by reserve callback. */ |
212 | struct lttng_kernel_ring_buffer_ctx_private priv; | |
213 | ||
f3bc08c5 | 214 | /* input received by lib_ring_buffer_reserve(), saved here. */ |
c7d9db61 MD |
215 | void *client_priv; /* Ring buffer client private data */ |
216 | ||
f3bc08c5 MD |
217 | size_t data_size; /* size of payload */ |
218 | int largest_align; /* | |
219 | * alignment of the largest element | |
220 | * in the payload | |
221 | */ | |
346cb5ee | 222 | struct lttng_kernel_probe_ctx *probe_ctx; /* Probe context */ |
f3bc08c5 MD |
223 | }; |
224 | ||
225 | /** | |
226 | * lib_ring_buffer_ctx_init - initialize ring buffer context | |
227 | * @ctx: ring buffer context to initialize | |
c7d9db61 | 228 | * @client_priv: client private data |
3cae7f22 | 229 | * @data_size: size of record data payload. It must be greater than 0. |
f3bc08c5 | 230 | * @largest_align: largest alignment within data payload types |
f3bc08c5 MD |
231 | */ |
232 | static inline | |
e27e4381 | 233 | void lib_ring_buffer_ctx_init(struct lttng_kernel_ring_buffer_ctx *ctx, |
c7d9db61 | 234 | void *client_priv, |
f3bc08c5 | 235 | size_t data_size, int largest_align, |
346cb5ee | 236 | struct lttng_kernel_probe_ctx *probe_ctx) |
f3bc08c5 | 237 | { |
c7d9db61 | 238 | ctx->client_priv = client_priv; |
f3bc08c5 MD |
239 | ctx->data_size = data_size; |
240 | ctx->largest_align = largest_align; | |
c7d9db61 | 241 | ctx->probe_ctx = probe_ctx; |
f3bc08c5 MD |
242 | } |
243 | ||
244 | /* | |
245 | * Reservation flags. | |
246 | * | |
247 | * RING_BUFFER_RFLAG_FULL_TSC | |
248 | * | |
249 | * This flag is passed to record_header_size() and to the primitive used to | |
250 | * write the record header. It indicates that the full 64-bit time value is | |
251 | * needed in the record header. If this flag is not set, the record header needs | |
252 | * only to contain "tsc_bits" bit of time value. | |
253 | * | |
254 | * Reservation flags can be added by the client, starting from | |
255 | * "(RING_BUFFER_FLAGS_END << 0)". It can be used to pass information from | |
256 | * record_header_size() to lib_ring_buffer_write_record_header(). | |
257 | */ | |
258 | #define RING_BUFFER_RFLAG_FULL_TSC (1U << 0) | |
259 | #define RING_BUFFER_RFLAG_END (1U << 1) | |
260 | ||
ae090dc5 | 261 | #ifndef LTTNG_TRACER_CORE_H |
2df37e95 | 262 | #error "lttng/tracer-core.h is needed for RING_BUFFER_ALIGN define" |
ae090dc5 MD |
263 | #endif |
264 | ||
f3bc08c5 MD |
265 | /* |
266 | * We need to define RING_BUFFER_ALIGN_ATTR so it is known early at | |
267 | * compile-time. We have to duplicate the "config->align" information and the | |
268 | * definition here because config->align is used both in the slow and fast | |
269 | * paths, but RING_BUFFER_ALIGN_ATTR is only available for the client code. | |
270 | */ | |
271 | #ifdef RING_BUFFER_ALIGN | |
272 | ||
273 | # define RING_BUFFER_ALIGN_ATTR /* Default arch alignment */ | |
274 | ||
275 | /* | |
276 | * Calculate the offset needed to align the type. | |
277 | * size_of_type must be non-zero. | |
278 | */ | |
279 | static inline | |
280 | unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type) | |
281 | { | |
282 | return offset_align(align_drift, size_of_type); | |
283 | } | |
284 | ||
285 | #else | |
286 | ||
287 | # define RING_BUFFER_ALIGN_ATTR __attribute__((packed)) | |
288 | ||
289 | /* | |
290 | * Calculate the offset needed to align the type. | |
291 | * size_of_type must be non-zero. | |
292 | */ | |
293 | static inline | |
294 | unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type) | |
295 | { | |
296 | return 0; | |
297 | } | |
298 | ||
299 | #endif | |
300 | ||
301 | /** | |
302 | * lib_ring_buffer_align_ctx - Align context offset on "alignment" | |
303 | * @ctx: ring buffer context. | |
304 | */ | |
305 | static inline | |
e27e4381 | 306 | void lib_ring_buffer_align_ctx(struct lttng_kernel_ring_buffer_ctx *ctx, |
f3bc08c5 MD |
307 | size_t alignment) |
308 | { | |
c7d9db61 | 309 | ctx->priv.buf_offset += lib_ring_buffer_align(ctx->priv.buf_offset, |
f3bc08c5 MD |
310 | alignment); |
311 | } | |
312 | ||
313 | /* | |
314 | * lib_ring_buffer_check_config() returns 0 on success. | |
315 | * Used internally to check for valid configurations at channel creation. | |
316 | */ | |
317 | static inline | |
a2a1b5ab | 318 | int lib_ring_buffer_check_config(const struct lttng_kernel_ring_buffer_config *config, |
f3bc08c5 MD |
319 | unsigned int switch_timer_interval, |
320 | unsigned int read_timer_interval) | |
321 | { | |
322 | if (config->alloc == RING_BUFFER_ALLOC_GLOBAL | |
323 | && config->sync == RING_BUFFER_SYNC_PER_CPU | |
324 | && switch_timer_interval) | |
325 | return -EINVAL; | |
326 | return 0; | |
327 | } | |
328 | ||
24591303 | 329 | #include <ringbuffer/vatomic.h> |
f3bc08c5 | 330 | |
886d51a3 | 331 | #endif /* _LIB_RING_BUFFER_CONFIG_H */ |