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