src/lttng-ring-buffer-event-notifier-client.h

   1 /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
   2  *
   3  * lttng-ring-buffer-event-notifier-client.h
   4  *
   5  * LTTng lib ring buffer event notifier client template.
   6  *
   7  * Copyright (C) 2010-2020 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  */
   9
  10 #include <linux/limits.h>
  11 #include <linux/module.h>
  12 #include <linux/types.h>
  13 #include <wrapper/vmalloc.h>    /* for wrapper_vmalloc_sync_mappings() */
  14 #include <lttng/abi.h>
  15 #include <lttng/events.h>
  16 #include <lttng/tracer.h>
  17 #include <wrapper/limits.h>
  18
  19 static struct lttng_transport lttng_relay_transport;
  20
  21 struct event_notifier_packet_header {
  22         uint8_t  header_end[0];
  23 };
  24
  25 struct event_notifier_record_header {
  26         uint32_t payload_len;           /* in bytes */
  27         uint8_t header_end[0];          /* End of header */
  28 };
  29
  30 static const struct lib_ring_buffer_config client_config;
  31
  32 static inline
  33 u64 lib_ring_buffer_clock_read(struct channel *chan)
  34 {
  35         return 0;
  36 }
  37
  38 static inline
  39 size_t record_header_size(const struct lib_ring_buffer_config *config,
  40                                  struct channel *chan, size_t offset,
  41                                  size_t *pre_header_padding,
  42                                  struct lib_ring_buffer_ctx *ctx,
  43                                  void *client_ctx)
  44 {
  45         size_t orig_offset = offset;
  46         size_t padding;
  47
  48         padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
  49         offset += padding;
  50
  51         offset += sizeof(uint32_t);
  52
  53         *pre_header_padding = padding;
  54
  55         return offset - orig_offset;
  56 }
  57
  58 #include <ringbuffer/api.h>
  59
  60 static u64 client_ring_buffer_clock_read(struct channel *chan)
  61 {
  62         return 0;
  63 }
  64
  65 static
  66 size_t client_record_header_size(const struct lib_ring_buffer_config *config,
  67                                  struct channel *chan, size_t offset,
  68                                  size_t *pre_header_padding,
  69                                  struct lib_ring_buffer_ctx *ctx,
  70                                  void *client_ctx)
  71 {
  72         return record_header_size(config, chan, offset,
  73                                   pre_header_padding, ctx, client_ctx);
  74 }
  75
  76 /**
  77  * client_packet_header_size - called on buffer-switch to a new sub-buffer
  78  *
  79  * Return header size without padding after the structure. Don't use packed
  80  * structure because gcc generates inefficient code on some architectures
  81  * (powerpc, mips..)
  82  */
  83 static size_t client_packet_header_size(void)
  84 {
  85         return offsetof(struct event_notifier_packet_header, header_end);
  86 }
  87
  88 static void client_buffer_begin(struct lib_ring_buffer *buf, u64 tsc,
  89                                 unsigned int subbuf_idx)
  90 {
  91 }
  92
  93 /*
  94  * offset is assumed to never be 0 here : never deliver a completely empty
  95  * subbuffer. data_size is between 1 and subbuf_size.
  96  */
  97 static void client_buffer_end(struct lib_ring_buffer *buf, u64 tsc,
  98                               unsigned int subbuf_idx, unsigned long data_size)
  99 {
 100 }
 101
 102 static int client_buffer_create(struct lib_ring_buffer *buf, void *priv,
 103                                 int cpu, const char *name)
 104 {
 105         return 0;
 106 }
 107
 108 static void client_buffer_finalize(struct lib_ring_buffer *buf, void *priv, int cpu)
 109 {
 110 }
 111
 112 static int client_timestamp_begin(const struct lib_ring_buffer_config *config,
 113                 struct lib_ring_buffer *buf, uint64_t *timestamp_begin)
 114 {
 115         return -ENOSYS;
 116 }
 117
 118 static int client_timestamp_end(const struct lib_ring_buffer_config *config,
 119                         struct lib_ring_buffer *bufb,
 120                         uint64_t *timestamp_end)
 121 {
 122         return -ENOSYS;
 123 }
 124
 125 static int client_events_discarded(const struct lib_ring_buffer_config *config,
 126                         struct lib_ring_buffer *bufb,
 127                         uint64_t *events_discarded)
 128 {
 129         return -ENOSYS;
 130 }
 131
 132 static int client_current_timestamp(const struct lib_ring_buffer_config *config,
 133                 struct lib_ring_buffer *bufb,
 134                 uint64_t *ts)
 135 {
 136         return -ENOSYS;
 137 }
 138
 139 static int client_content_size(const struct lib_ring_buffer_config *config,
 140                         struct lib_ring_buffer *bufb,
 141                         uint64_t *content_size)
 142 {
 143         return -ENOSYS;
 144 }
 145
 146 static int client_packet_size(const struct lib_ring_buffer_config *config,
 147                         struct lib_ring_buffer *bufb,
 148                         uint64_t *packet_size)
 149 {
 150         return -ENOSYS;
 151 }
 152
 153 static int client_stream_id(const struct lib_ring_buffer_config *config,
 154                         struct lib_ring_buffer *bufb,
 155                         uint64_t *stream_id)
 156 {
 157         return -ENOSYS;
 158 }
 159
 160 static int client_sequence_number(const struct lib_ring_buffer_config *config,
 161                         struct lib_ring_buffer *bufb,
 162                         uint64_t *seq)
 163 {
 164         return -ENOSYS;
 165 }
 166
 167 static
 168 int client_instance_id(const struct lib_ring_buffer_config *config,
 169                 struct lib_ring_buffer *bufb,
 170                 uint64_t *id)
 171 {
 172         return -ENOSYS;
 173 }
 174
 175 static void client_record_get(const struct lib_ring_buffer_config *config,
 176         struct channel *chan, struct lib_ring_buffer *buf,
 177         size_t offset, size_t *header_len,
 178         size_t *payload_len, u64 *timestamp)
 179 {
 180         struct event_notifier_record_header header;
 181         int ret;
 182
 183         ret = lib_ring_buffer_read(&buf->backend, offset, &header,
 184                         offsetof(struct event_notifier_record_header, header_end));
 185         CHAN_WARN_ON(chan, ret != offsetof(struct event_notifier_record_header, header_end));
 186         *header_len = offsetof(struct event_notifier_record_header, header_end);
 187         *payload_len = header.payload_len;
 188         *timestamp = 0;
 189 }
 190
 191 static const struct lib_ring_buffer_config client_config = {
 192         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 193         .cb.record_header_size = client_record_header_size,
 194         .cb.subbuffer_header_size = client_packet_header_size,
 195         .cb.buffer_begin = client_buffer_begin,
 196         .cb.buffer_end = client_buffer_end,
 197         .cb.buffer_create = client_buffer_create,
 198         .cb.buffer_finalize = client_buffer_finalize,
 199         .cb.record_get = client_record_get,
 200
 201         .tsc_bits = 0,
 202         .alloc = RING_BUFFER_ALLOC_GLOBAL,
 203         .sync = RING_BUFFER_SYNC_GLOBAL,
 204         .mode = RING_BUFFER_MODE_TEMPLATE,
 205         .backend = RING_BUFFER_PAGE,
 206         .output = RING_BUFFER_OUTPUT_TEMPLATE,
 207         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 208         .ipi = RING_BUFFER_NO_IPI_BARRIER,
 209         .wakeup = RING_BUFFER_WAKEUP_BY_WRITER,
 210 };
 211
 212 static
 213 void release_priv_ops(void *priv_ops)
 214 {
 215         module_put(THIS_MODULE);
 216 }
 217
 218 static
 219 void lttng_channel_destroy(struct channel *chan)
 220 {
 221         channel_destroy(chan);
 222 }
 223
 224 static
 225 struct channel *_channel_create(const char *name,
 226                                 void *priv, void *buf_addr,
 227                                 size_t subbuf_size, size_t num_subbuf,
 228                                 unsigned int switch_timer_interval,
 229                                 unsigned int read_timer_interval)
 230 {
 231         struct lttng_event_notifier_group *event_notifier_group = priv;
 232         struct channel *chan;
 233
 234         chan = channel_create(&client_config, name,
 235                               event_notifier_group, buf_addr,
 236                               subbuf_size, num_subbuf, switch_timer_interval,
 237                               read_timer_interval);
 238         if (chan) {
 239                 /*
 240                  * Ensure this module is not unloaded before we finish
 241                  * using lttng_relay_transport.ops.
 242                  */
 243                 if (!try_module_get(THIS_MODULE)) {
 244                         printk(KERN_WARNING "LTTng: Can't lock event_notifier transport module.\n");
 245                         goto error;
 246                 }
 247                 chan->backend.priv_ops = &lttng_relay_transport.ops;
 248                 chan->backend.release_priv_ops = release_priv_ops;
 249         }
 250         return chan;
 251
 252 error:
 253         lttng_channel_destroy(chan);
 254         return NULL;
 255 }
 256
 257 static
 258 struct lib_ring_buffer *lttng_buffer_read_open(struct channel *chan)
 259 {
 260         struct lib_ring_buffer *buf;
 261
 262         buf = channel_get_ring_buffer(&client_config, chan, 0);
 263         if (!lib_ring_buffer_open_read(buf))
 264                 return buf;
 265         return NULL;
 266 }
 267
 268 static
 269 int lttng_buffer_has_read_closed_stream(struct channel *chan)
 270 {
 271         struct lib_ring_buffer *buf;
 272         int cpu;
 273
 274         for_each_channel_cpu(cpu, chan) {
 275                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 276                 if (!atomic_long_read(&buf->active_readers))
 277                         return 1;
 278         }
 279         return 0;
 280 }
 281
 282 static
 283 void lttng_buffer_read_close(struct lib_ring_buffer *buf)
 284 {
 285         lib_ring_buffer_release_read(buf);
 286 }
 287
 288 static
 289 void lttng_write_event_notifier_header(const struct lib_ring_buffer_config *config,
 290                             struct lib_ring_buffer_ctx *ctx)
 291 {
 292         uint32_t data_size;
 293
 294         WARN_ON_ONCE(ctx->data_size > U32_MAX);
 295
 296         data_size = (uint32_t) ctx->data_size;
 297
 298         lib_ring_buffer_write(config, ctx, &data_size, sizeof(data_size));
 299
 300         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 301 }
 302
 303 static
 304 int lttng_event_reserve(struct lib_ring_buffer_ctx *ctx, uint32_t event_id)
 305 {
 306         int ret;
 307
 308         ret = lib_ring_buffer_reserve(&client_config, ctx, NULL);
 309         if (ret)
 310                 return ret;
 311         lib_ring_buffer_backend_get_pages(&client_config, ctx,
 312                         &ctx->backend_pages);
 313
 314         lttng_write_event_notifier_header(&client_config, ctx);
 315         return 0;
 316 }
 317
 318 static
 319 void lttng_event_commit(struct lib_ring_buffer_ctx *ctx)
 320 {
 321         lib_ring_buffer_commit(&client_config, ctx);
 322 }
 323
 324 static
 325 void lttng_event_write(struct lib_ring_buffer_ctx *ctx, const void *src,
 326                      size_t len)
 327 {
 328         lib_ring_buffer_write(&client_config, ctx, src, len);
 329 }
 330
 331 static
 332 void lttng_event_write_from_user(struct lib_ring_buffer_ctx *ctx,
 333                                const void __user *src, size_t len)
 334 {
 335         lib_ring_buffer_copy_from_user_inatomic(&client_config, ctx, src, len);
 336 }
 337
 338 static
 339 void lttng_event_memset(struct lib_ring_buffer_ctx *ctx,
 340                 int c, size_t len)
 341 {
 342         lib_ring_buffer_memset(&client_config, ctx, c, len);
 343 }
 344
 345 static
 346 void lttng_event_strcpy(struct lib_ring_buffer_ctx *ctx, const char *src,
 347                 size_t len)
 348 {
 349         lib_ring_buffer_strcpy(&client_config, ctx, src, len, '#');
 350 }
 351
 352 static
 353 size_t lttng_packet_avail_size(struct channel *chan)
 354 {
 355         unsigned long o_begin;
 356         struct lib_ring_buffer *buf;
 357
 358         buf = chan->backend.buf;        /* Only for global buffer ! */
 359         o_begin = v_read(&client_config, &buf->offset);
 360         if (subbuf_offset(o_begin, chan) != 0) {
 361                 return chan->backend.subbuf_size - subbuf_offset(o_begin, chan);
 362         } else {
 363                 return chan->backend.subbuf_size - subbuf_offset(o_begin, chan)
 364                         - sizeof(struct event_notifier_packet_header);
 365         }
 366 }
 367
 368 static
 369 wait_queue_head_t *lttng_get_writer_buf_wait_queue(struct channel *chan, int cpu)
 370 {
 371         struct lib_ring_buffer *buf = channel_get_ring_buffer(&client_config,
 372                                         chan, cpu);
 373         return &buf->write_wait;
 374 }
 375
 376 static
 377 wait_queue_head_t *lttng_get_hp_wait_queue(struct channel *chan)
 378 {
 379         return &chan->hp_wait;
 380 }
 381
 382 static
 383 int lttng_is_finalized(struct channel *chan)
 384 {
 385         return lib_ring_buffer_channel_is_finalized(chan);
 386 }
 387
 388 static
 389 int lttng_is_disabled(struct channel *chan)
 390 {
 391         return lib_ring_buffer_channel_is_disabled(chan);
 392 }
 393
 394 static struct lttng_transport lttng_relay_transport = {
 395         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
 396         .owner = THIS_MODULE,
 397         .ops = {
 398                 .channel_create = _channel_create,
 399                 .channel_destroy = lttng_channel_destroy,
 400                 .buffer_read_open = lttng_buffer_read_open,
 401                 .buffer_has_read_closed_stream =
 402                         lttng_buffer_has_read_closed_stream,
 403                 .buffer_read_close = lttng_buffer_read_close,
 404                 .event_reserve = lttng_event_reserve,
 405                 .event_commit = lttng_event_commit,
 406                 .event_write_from_user = lttng_event_write_from_user,
 407                 .event_memset = lttng_event_memset,
 408                 .event_write = lttng_event_write,
 409                 .event_strcpy = lttng_event_strcpy,
 410                 .packet_avail_size = lttng_packet_avail_size,
 411                 .get_writer_buf_wait_queue = lttng_get_writer_buf_wait_queue,
 412                 .get_hp_wait_queue = lttng_get_hp_wait_queue,
 413                 .is_finalized = lttng_is_finalized,
 414                 .is_disabled = lttng_is_disabled,
 415                 .timestamp_begin = client_timestamp_begin,
 416                 .timestamp_end = client_timestamp_end,
 417                 .events_discarded = client_events_discarded,
 418                 .content_size = client_content_size,
 419                 .packet_size = client_packet_size,
 420                 .stream_id = client_stream_id,
 421                 .current_timestamp = client_current_timestamp,
 422                 .sequence_number = client_sequence_number,
 423                 .instance_id = client_instance_id,
 424         },
 425 };
 426
 427 static int __init lttng_ring_buffer_event_notifier_client_init(void)
 428 {
 429         /*
 430          * This vmalloc sync all also takes care of the lib ring buffer
 431          * vmalloc'd module pages when it is built as a module into LTTng.
 432          */
 433         wrapper_vmalloc_sync_mappings();
 434         lttng_transport_register(&lttng_relay_transport);
 435         return 0;
 436 }
 437
 438 module_init(lttng_ring_buffer_event_notifier_client_init);
 439
 440 static void __exit lttng_ring_buffer_event_notifier_client_exit(void)
 441 {
 442         lttng_transport_unregister(&lttng_relay_transport);
 443 }
 444
 445 module_exit(lttng_ring_buffer_event_notifier_client_exit);
 446
 447 MODULE_LICENSE("GPL and additional rights");
 448 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
 449 MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING
 450                    " client");
 451 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
 452         __stringify(LTTNG_MODULES_MINOR_VERSION) "."
 453         __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
 454         LTTNG_MODULES_EXTRAVERSION);