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/events-internal.h>
  17 #include <lttng/tracer.h>
  18 #include <wrapper/limits.h>
  19
  20 static struct lttng_transport lttng_relay_transport;
  21
  22 struct event_notifier_packet_header {
  23         uint8_t  header_end[0];
  24 };
  25
  26 struct event_notifier_record_header {
  27         uint32_t payload_len;           /* in bytes */
  28         uint8_t header_end[0];          /* End of header */
  29 };
  30
  31 static const struct lttng_kernel_ring_buffer_config client_config;
  32
  33 static inline
  34 u64 lib_ring_buffer_clock_read(struct lttng_kernel_ring_buffer_channel *chan)
  35 {
  36         return 0;
  37 }
  38
  39 static inline
  40 size_t record_header_size(const struct lttng_kernel_ring_buffer_config *config,
  41                                  struct lttng_kernel_ring_buffer_channel *chan, size_t offset,
  42                                  size_t *pre_header_padding,
  43                                  struct lttng_kernel_ring_buffer_ctx *ctx,
  44                                  void *client_ctx)
  45 {
  46         size_t orig_offset = offset;
  47         size_t padding;
  48
  49         padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
  50         offset += padding;
  51
  52         offset += sizeof(uint32_t);
  53
  54         *pre_header_padding = padding;
  55
  56         return offset - orig_offset;
  57 }
  58
  59 #include <ringbuffer/api.h>
  60
  61 static u64 client_ring_buffer_clock_read(struct lttng_kernel_ring_buffer_channel *chan)
  62 {
  63         return 0;
  64 }
  65
  66 static
  67 size_t client_record_header_size(const struct lttng_kernel_ring_buffer_config *config,
  68                                  struct lttng_kernel_ring_buffer_channel *chan, size_t offset,
  69                                  size_t *pre_header_padding,
  70                                  struct lttng_kernel_ring_buffer_ctx *ctx,
  71                                  void *client_ctx)
  72 {
  73         return record_header_size(config, chan, offset,
  74                                   pre_header_padding, ctx, client_ctx);
  75 }
  76
  77 /**
  78  * client_packet_header_size - called on buffer-switch to a new sub-buffer
  79  *
  80  * Return header size without padding after the structure. Don't use packed
  81  * structure because gcc generates inefficient code on some architectures
  82  * (powerpc, mips..)
  83  */
  84 static size_t client_packet_header_size(void)
  85 {
  86         return offsetof(struct event_notifier_packet_header, header_end);
  87 }
  88
  89 static void client_buffer_begin(struct lttng_kernel_ring_buffer *buf, u64 tsc,
  90                                 unsigned int subbuf_idx)
  91 {
  92 }
  93
  94 /*
  95  * offset is assumed to never be 0 here : never deliver a completely empty
  96  * subbuffer. data_size is between 1 and subbuf_size.
  97  */
  98 static void client_buffer_end(struct lttng_kernel_ring_buffer *buf, u64 tsc,
  99                               unsigned int subbuf_idx, unsigned long data_size)
 100 {
 101 }
 102
 103 static int client_buffer_create(struct lttng_kernel_ring_buffer *buf, void *priv,
 104                                 int cpu, const char *name)
 105 {
 106         return 0;
 107 }
 108
 109 static void client_buffer_finalize(struct lttng_kernel_ring_buffer *buf, void *priv, int cpu)
 110 {
 111 }
 112
 113 static int client_timestamp_begin(const struct lttng_kernel_ring_buffer_config *config,
 114                 struct lttng_kernel_ring_buffer *buf, uint64_t *timestamp_begin)
 115 {
 116         return -ENOSYS;
 117 }
 118
 119 static int client_timestamp_end(const struct lttng_kernel_ring_buffer_config *config,
 120                         struct lttng_kernel_ring_buffer *bufb,
 121                         uint64_t *timestamp_end)
 122 {
 123         return -ENOSYS;
 124 }
 125
 126 static int client_events_discarded(const struct lttng_kernel_ring_buffer_config *config,
 127                         struct lttng_kernel_ring_buffer *bufb,
 128                         uint64_t *events_discarded)
 129 {
 130         return -ENOSYS;
 131 }
 132
 133 static int client_current_timestamp(const struct lttng_kernel_ring_buffer_config *config,
 134                 struct lttng_kernel_ring_buffer *bufb,
 135                 uint64_t *ts)
 136 {
 137         return -ENOSYS;
 138 }
 139
 140 static int client_content_size(const struct lttng_kernel_ring_buffer_config *config,
 141                         struct lttng_kernel_ring_buffer *bufb,
 142                         uint64_t *content_size)
 143 {
 144         return -ENOSYS;
 145 }
 146
 147 static int client_packet_size(const struct lttng_kernel_ring_buffer_config *config,
 148                         struct lttng_kernel_ring_buffer *bufb,
 149                         uint64_t *packet_size)
 150 {
 151         return -ENOSYS;
 152 }
 153
 154 static int client_stream_id(const struct lttng_kernel_ring_buffer_config *config,
 155                         struct lttng_kernel_ring_buffer *bufb,
 156                         uint64_t *stream_id)
 157 {
 158         return -ENOSYS;
 159 }
 160
 161 static int client_sequence_number(const struct lttng_kernel_ring_buffer_config *config,
 162                         struct lttng_kernel_ring_buffer *bufb,
 163                         uint64_t *seq)
 164 {
 165         return -ENOSYS;
 166 }
 167
 168 static
 169 int client_instance_id(const struct lttng_kernel_ring_buffer_config *config,
 170                 struct lttng_kernel_ring_buffer *bufb,
 171                 uint64_t *id)
 172 {
 173         return -ENOSYS;
 174 }
 175
 176 static void client_record_get(const struct lttng_kernel_ring_buffer_config *config,
 177         struct lttng_kernel_ring_buffer_channel *chan, struct lttng_kernel_ring_buffer *buf,
 178         size_t offset, size_t *header_len,
 179         size_t *payload_len, u64 *timestamp)
 180 {
 181         struct event_notifier_record_header header;
 182         int ret;
 183
 184         ret = lib_ring_buffer_read(&buf->backend, offset, &header,
 185                         offsetof(struct event_notifier_record_header, header_end));
 186         CHAN_WARN_ON(chan, ret != offsetof(struct event_notifier_record_header, header_end));
 187         *header_len = offsetof(struct event_notifier_record_header, header_end);
 188         *payload_len = header.payload_len;
 189         *timestamp = 0;
 190 }
 191
 192 static const struct lttng_kernel_ring_buffer_config client_config = {
 193         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 194         .cb.record_header_size = client_record_header_size,
 195         .cb.subbuffer_header_size = client_packet_header_size,
 196         .cb.buffer_begin = client_buffer_begin,
 197         .cb.buffer_end = client_buffer_end,
 198         .cb.buffer_create = client_buffer_create,
 199         .cb.buffer_finalize = client_buffer_finalize,
 200         .cb.record_get = client_record_get,
 201
 202         .tsc_bits = 0,
 203         .alloc = RING_BUFFER_ALLOC_GLOBAL,
 204         .sync = RING_BUFFER_SYNC_GLOBAL,
 205         .mode = RING_BUFFER_MODE_TEMPLATE,
 206         .backend = RING_BUFFER_PAGE,
 207         .output = RING_BUFFER_OUTPUT_TEMPLATE,
 208         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 209         .ipi = RING_BUFFER_NO_IPI_BARRIER,
 210         .wakeup = RING_BUFFER_WAKEUP_BY_WRITER,
 211 };
 212
 213 static
 214 void release_priv_ops(void *priv_ops)
 215 {
 216         module_put(THIS_MODULE);
 217 }
 218
 219 static
 220 void lttng_channel_destroy(struct lttng_kernel_ring_buffer_channel *chan)
 221 {
 222         channel_destroy(chan);
 223 }
 224
 225 static
 226 struct lttng_kernel_ring_buffer_channel *_channel_create(const char *name,
 227                                 void *priv, void *buf_addr,
 228                                 size_t subbuf_size, size_t num_subbuf,
 229                                 unsigned int switch_timer_interval,
 230                                 unsigned int read_timer_interval)
 231 {
 232         struct lttng_event_notifier_group *event_notifier_group = priv;
 233         struct lttng_kernel_ring_buffer_channel *chan;
 234
 235         chan = channel_create(&client_config, name,
 236                               event_notifier_group, buf_addr,
 237                               subbuf_size, num_subbuf, switch_timer_interval,
 238                               read_timer_interval);
 239         if (chan) {
 240                 /*
 241                  * Ensure this module is not unloaded before we finish
 242                  * using lttng_relay_transport.ops.
 243                  */
 244                 if (!try_module_get(THIS_MODULE)) {
 245                         printk(KERN_WARNING "LTTng: Can't lock event_notifier transport module.\n");
 246                         goto error;
 247                 }
 248                 chan->backend.priv_ops = &lttng_relay_transport.ops;
 249                 chan->backend.release_priv_ops = release_priv_ops;
 250         }
 251         return chan;
 252
 253 error:
 254         lttng_channel_destroy(chan);
 255         return NULL;
 256 }
 257
 258 static
 259 struct lttng_kernel_ring_buffer *lttng_buffer_read_open(struct lttng_kernel_ring_buffer_channel *chan)
 260 {
 261         struct lttng_kernel_ring_buffer *buf;
 262
 263         buf = channel_get_ring_buffer(&client_config, chan, 0);
 264         if (!lib_ring_buffer_open_read(buf))
 265                 return buf;
 266         return NULL;
 267 }
 268
 269 static
 270 int lttng_buffer_has_read_closed_stream(struct lttng_kernel_ring_buffer_channel *chan)
 271 {
 272         struct lttng_kernel_ring_buffer *buf;
 273         int cpu;
 274
 275         for_each_channel_cpu(cpu, chan) {
 276                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 277                 if (!atomic_long_read(&buf->active_readers))
 278                         return 1;
 279         }
 280         return 0;
 281 }
 282
 283 static
 284 void lttng_buffer_read_close(struct lttng_kernel_ring_buffer *buf)
 285 {
 286         lib_ring_buffer_release_read(buf);
 287 }
 288
 289 static
 290 void lttng_write_event_notifier_header(const struct lttng_kernel_ring_buffer_config *config,
 291                             struct lttng_kernel_ring_buffer_ctx *ctx)
 292 {
 293         uint32_t data_size;
 294
 295         WARN_ON_ONCE(ctx->data_size > U32_MAX);
 296
 297         data_size = (uint32_t) ctx->data_size;
 298
 299         lib_ring_buffer_write(config, ctx, &data_size, sizeof(data_size));
 300
 301         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 302 }
 303
 304 static
 305 int lttng_event_reserve(struct lttng_kernel_ring_buffer_ctx *ctx)
 306 {
 307         struct lttng_kernel_ring_buffer_channel *chan = ctx->client_priv;
 308         int ret;
 309
 310         memset(&ctx->priv, 0, sizeof(ctx->priv));
 311         ctx->priv.chan = chan;
 312
 313         ret = lib_ring_buffer_reserve(&client_config, ctx, NULL);
 314         if (ret)
 315                 return ret;
 316         lib_ring_buffer_backend_get_pages(&client_config, ctx,
 317                         &ctx->priv.backend_pages);
 318
 319         lttng_write_event_notifier_header(&client_config, ctx);
 320         return 0;
 321 }
 322
 323 static
 324 void lttng_event_commit(struct lttng_kernel_ring_buffer_ctx *ctx)
 325 {
 326         lib_ring_buffer_commit(&client_config, ctx);
 327 }
 328
 329 static
 330 void lttng_event_write(struct lttng_kernel_ring_buffer_ctx *ctx, const void *src,
 331                      size_t len, size_t alignment)
 332 {
 333         lib_ring_buffer_align_ctx(ctx, alignment);
 334         lib_ring_buffer_write(&client_config, ctx, src, len);
 335 }
 336
 337 static
 338 void lttng_event_write_from_user(struct lttng_kernel_ring_buffer_ctx *ctx,
 339                                const void __user *src, size_t len, size_t alignment)
 340 {
 341         lib_ring_buffer_align_ctx(ctx, alignment);
 342         lib_ring_buffer_copy_from_user_inatomic(&client_config, ctx, src, len);
 343 }
 344
 345 static
 346 void lttng_event_memset(struct lttng_kernel_ring_buffer_ctx *ctx,
 347                 int c, size_t len)
 348 {
 349         lib_ring_buffer_memset(&client_config, ctx, c, len);
 350 }
 351
 352 static
 353 void lttng_event_strcpy(struct lttng_kernel_ring_buffer_ctx *ctx, const char *src,
 354                 size_t len)
 355 {
 356         lib_ring_buffer_strcpy(&client_config, ctx, src, len, '#');
 357 }
 358
 359 static
 360 size_t lttng_packet_avail_size(struct lttng_kernel_ring_buffer_channel *chan)
 361 {
 362         unsigned long o_begin;
 363         struct lttng_kernel_ring_buffer *buf;
 364
 365         buf = chan->backend.buf;        /* Only for global buffer ! */
 366         o_begin = v_read(&client_config, &buf->offset);
 367         if (subbuf_offset(o_begin, chan) != 0) {
 368                 return chan->backend.subbuf_size - subbuf_offset(o_begin, chan);
 369         } else {
 370                 return chan->backend.subbuf_size - subbuf_offset(o_begin, chan)
 371                         - sizeof(struct event_notifier_packet_header);
 372         }
 373 }
 374
 375 static
 376 wait_queue_head_t *lttng_get_writer_buf_wait_queue(struct lttng_kernel_ring_buffer_channel *chan, int cpu)
 377 {
 378         struct lttng_kernel_ring_buffer *buf = channel_get_ring_buffer(&client_config,
 379                                         chan, cpu);
 380         return &buf->write_wait;
 381 }
 382
 383 static
 384 wait_queue_head_t *lttng_get_hp_wait_queue(struct lttng_kernel_ring_buffer_channel *chan)
 385 {
 386         return &chan->hp_wait;
 387 }
 388
 389 static
 390 int lttng_is_finalized(struct lttng_kernel_ring_buffer_channel *chan)
 391 {
 392         return lib_ring_buffer_channel_is_finalized(chan);
 393 }
 394
 395 static
 396 int lttng_is_disabled(struct lttng_kernel_ring_buffer_channel *chan)
 397 {
 398         return lib_ring_buffer_channel_is_disabled(chan);
 399 }
 400
 401 static struct lttng_transport lttng_relay_transport = {
 402         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
 403         .owner = THIS_MODULE,
 404         .ops = {
 405                 .priv = __LTTNG_COMPOUND_LITERAL(struct lttng_kernel_channel_buffer_ops_private, {
 406                         .pub = &lttng_relay_transport.ops,
 407                         .channel_create = _channel_create,
 408                         .channel_destroy = lttng_channel_destroy,
 409                         .buffer_read_open = lttng_buffer_read_open,
 410                         .buffer_has_read_closed_stream =
 411                                 lttng_buffer_has_read_closed_stream,
 412                         .buffer_read_close = lttng_buffer_read_close,
 413                         .packet_avail_size = lttng_packet_avail_size,
 414                         .get_writer_buf_wait_queue = lttng_get_writer_buf_wait_queue,
 415                         .get_hp_wait_queue = lttng_get_hp_wait_queue,
 416                         .is_finalized = lttng_is_finalized,
 417                         .is_disabled = lttng_is_disabled,
 418                         .timestamp_begin = client_timestamp_begin,
 419                         .timestamp_end = client_timestamp_end,
 420                         .events_discarded = client_events_discarded,
 421                         .content_size = client_content_size,
 422                         .packet_size = client_packet_size,
 423                         .stream_id = client_stream_id,
 424                         .current_timestamp = client_current_timestamp,
 425                         .sequence_number = client_sequence_number,
 426                         .instance_id = client_instance_id,
 427                 }),
 428                 .event_reserve = lttng_event_reserve,
 429                 .event_commit = lttng_event_commit,
 430                 .event_write_from_user = lttng_event_write_from_user,
 431                 .event_memset = lttng_event_memset,
 432                 .event_write = lttng_event_write,
 433                 .event_strcpy = lttng_event_strcpy,
 434         },
 435 };
 436
 437 static int __init lttng_ring_buffer_event_notifier_client_init(void)
 438 {
 439         /*
 440          * This vmalloc sync all also takes care of the lib ring buffer
 441          * vmalloc'd module pages when it is built as a module into LTTng.
 442          */
 443         wrapper_vmalloc_sync_mappings();
 444         lttng_transport_register(&lttng_relay_transport);
 445         return 0;
 446 }
 447
 448 module_init(lttng_ring_buffer_event_notifier_client_init);
 449
 450 static void __exit lttng_ring_buffer_event_notifier_client_exit(void)
 451 {
 452         lttng_transport_unregister(&lttng_relay_transport);
 453 }
 454
 455 module_exit(lttng_ring_buffer_event_notifier_client_exit);
 456
 457 MODULE_LICENSE("GPL and additional rights");
 458 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
 459 MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING
 460                    " client");
 461 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
 462         __stringify(LTTNG_MODULES_MINOR_VERSION) "."
 463         __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
 464         LTTNG_MODULES_EXTRAVERSION);