src/common/ringbuffer-clients/template.h

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-only
   3  *
   4  * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * LTTng lib ring buffer client template.
   7  */
   8
   9 #include <limits.h>
  10 #include <stddef.h>
  11 #include <stdint.h>
  12
  13 #include <lttng/urcu/pointer.h>
  14 #include <urcu/tls-compat.h>
  15
  16 #include "common/events.h"
  17 #include "common/bitfield.h"
  18 #include "common/align.h"
  19 #include "common/clock.h"
  20 #include "common/ringbuffer/frontend_types.h"
  21
  22 #define LTTNG_COMPACT_EVENT_BITS        5
  23 #define LTTNG_COMPACT_TIMESTAMP_BITS    27
  24
  25 /*
  26  * Keep the natural field alignment for _each field_ within this structure if
  27  * you ever add/remove a field from this header. Packed attribute is not used
  28  * because gcc generates poor code on at least powerpc and mips. Don't ever
  29  * let gcc add padding between the structure elements.
  30  */
  31
  32 struct packet_header {
  33         /* Trace packet header */
  34         uint32_t magic;                 /*
  35                                          * Trace magic number.
  36                                          * contains endianness information.
  37                                          */
  38         uint8_t uuid[LTTNG_UST_UUID_LEN];
  39         uint32_t stream_id;
  40         uint64_t stream_instance_id;
  41
  42         struct {
  43                 /* Stream packet context */
  44                 uint64_t timestamp_begin;       /* Cycle count at subbuffer start */
  45                 uint64_t timestamp_end;         /* Cycle count at subbuffer end */
  46                 uint64_t content_size;          /* Size of data in subbuffer */
  47                 uint64_t packet_size;           /* Subbuffer size (include padding) */
  48                 uint64_t packet_seq_num;        /* Packet sequence number */
  49                 unsigned long events_discarded; /*
  50                                                  * Events lost in this subbuffer since
  51                                                  * the beginning of the trace.
  52                                                  * (may overflow)
  53                                                  */
  54                 uint32_t cpu_id;                /* CPU id associated with stream */
  55                 uint8_t header_end;             /* End of header */
  56         } ctx;
  57 };
  58
  59 struct lttng_client_ctx {
  60         size_t packet_context_len;
  61         size_t event_context_len;
  62         struct lttng_ust_ctx *chan_ctx;
  63 };
  64
  65 /*
  66  * Indexed by lib_ring_buffer_nesting_count().
  67  */
  68 typedef struct lttng_ust_ring_buffer_ctx_private private_ctx_stack_t[LIB_RING_BUFFER_MAX_NESTING];
  69 static DEFINE_URCU_TLS(private_ctx_stack_t, private_ctx_stack);
  70
  71 /*
  72  * Force a read (imply TLS allocation for dlopen) of TLS variables.
  73  */
  74 void RING_BUFFER_MODE_TEMPLATE_ALLOC_TLS(void)
  75 {
  76         __asm__ __volatile__ ("" : : "m" (URCU_TLS(private_ctx_stack)));
  77 }
  78
  79 static inline uint64_t lib_ring_buffer_clock_read(
  80                 struct lttng_ust_ring_buffer_channel *chan __attribute__((unused)))
  81 {
  82         return trace_clock_read64();
  83 }
  84
  85 static inline
  86 size_t ctx_get_aligned_size(size_t offset, struct lttng_ust_ctx *ctx,
  87                 size_t ctx_len)
  88 {
  89         size_t orig_offset = offset;
  90
  91         if (caa_likely(!ctx))
  92                 return 0;
  93         offset += lttng_ust_ring_buffer_align(offset, ctx->largest_align);
  94         offset += ctx_len;
  95         return offset - orig_offset;
  96 }
  97
  98 static inline
  99 void ctx_get_struct_size(struct lttng_ust_ring_buffer_ctx *bufctx,
 100                 struct lttng_ust_ctx *ctx, size_t *ctx_len)
 101 {
 102         int i;
 103         size_t offset = 0;
 104
 105         if (caa_likely(!ctx)) {
 106                 *ctx_len = 0;
 107                 return;
 108         }
 109         for (i = 0; i < ctx->nr_fields; i++)
 110                 offset += ctx->fields[i].get_size(ctx->fields[i].priv, bufctx->probe_ctx, offset);
 111         *ctx_len = offset;
 112 }
 113
 114 static inline
 115 void ctx_record(struct lttng_ust_ring_buffer_ctx *bufctx,
 116                 struct lttng_ust_channel_buffer *chan,
 117                 struct lttng_ust_ctx *ctx)
 118 {
 119         int i;
 120
 121         if (caa_likely(!ctx))
 122                 return;
 123         lttng_ust_ring_buffer_align_ctx(bufctx, ctx->largest_align);
 124         for (i = 0; i < ctx->nr_fields; i++)
 125                 ctx->fields[i].record(ctx->fields[i].priv, bufctx->probe_ctx, bufctx, chan);
 126 }
 127
 128 /*
 129  * record_header_size - Calculate the header size and padding necessary.
 130  * @config: ring buffer instance configuration
 131  * @chan: channel
 132  * @offset: offset in the write buffer
 133  * @pre_header_padding: padding to add before the header (output)
 134  * @ctx: reservation context
 135  *
 136  * Returns the event header size (including padding).
 137  *
 138  * The payload must itself determine its own alignment from the biggest type it
 139  * contains.
 140  */
 141 static __inline__
 142 size_t record_header_size(
 143                 const struct lttng_ust_ring_buffer_config *config __attribute__((unused)),
 144                 struct lttng_ust_ring_buffer_channel *chan,
 145                 size_t offset,
 146                 size_t *pre_header_padding,
 147                 struct lttng_ust_ring_buffer_ctx *ctx,
 148                 struct lttng_client_ctx *client_ctx)
 149 {
 150         struct lttng_ust_channel_buffer *lttng_chan = channel_get_private(chan);
 151         size_t orig_offset = offset;
 152         size_t padding;
 153
 154         switch (lttng_chan->priv->header_type) {
 155         case 1: /* compact */
 156                 padding = lttng_ust_ring_buffer_align(offset, lttng_ust_rb_alignof(uint32_t));
 157                 offset += padding;
 158                 if (!(ctx->priv->rflags & (RING_BUFFER_RFLAG_FULL_TIMESTAMP | LTTNG_RFLAG_EXTENDED))) {
 159                         offset += sizeof(uint32_t);     /* id and timestamp */
 160                 } else {
 161                         /* Minimum space taken by LTTNG_COMPACT_EVENT_BITS id */
 162                         offset += (LTTNG_COMPACT_EVENT_BITS + CHAR_BIT - 1) / CHAR_BIT;
 163                         /* Align extended struct on largest member */
 164                         offset += lttng_ust_ring_buffer_align(offset, lttng_ust_rb_alignof(uint64_t));
 165                         offset += sizeof(uint32_t);     /* id */
 166                         offset += lttng_ust_ring_buffer_align(offset, lttng_ust_rb_alignof(uint64_t));
 167                         offset += sizeof(uint64_t);     /* timestamp */
 168                 }
 169                 break;
 170         case 2: /* large */
 171                 padding = lttng_ust_ring_buffer_align(offset, lttng_ust_rb_alignof(uint16_t));
 172                 offset += padding;
 173                 offset += sizeof(uint16_t);
 174                 if (!(ctx->priv->rflags & (RING_BUFFER_RFLAG_FULL_TIMESTAMP | LTTNG_RFLAG_EXTENDED))) {
 175                         offset += lttng_ust_ring_buffer_align(offset, lttng_ust_rb_alignof(uint32_t));
 176                         offset += sizeof(uint32_t);     /* timestamp */
 177                 } else {
 178                         /* Align extended struct on largest member */
 179                         offset += lttng_ust_ring_buffer_align(offset, lttng_ust_rb_alignof(uint64_t));
 180                         offset += sizeof(uint32_t);     /* id */
 181                         offset += lttng_ust_ring_buffer_align(offset, lttng_ust_rb_alignof(uint64_t));
 182                         offset += sizeof(uint64_t);     /* timestamp */
 183                 }
 184                 break;
 185         default:
 186                 padding = 0;
 187                 WARN_ON_ONCE(1);
 188         }
 189         offset += ctx_get_aligned_size(offset, client_ctx->chan_ctx,
 190                         client_ctx->packet_context_len);
 191         *pre_header_padding = padding;
 192         return offset - orig_offset;
 193 }
 194
 195 #include "common/ringbuffer/api.h"
 196 #include "common/ringbuffer-clients/clients.h"
 197
 198 static
 199 void lttng_write_event_header_slow(const struct lttng_ust_ring_buffer_config *config,
 200                                  struct lttng_ust_ring_buffer_ctx *ctx,
 201                                  struct lttng_client_ctx *client_ctx,
 202                                  uint32_t event_id);
 203
 204 /*
 205  * lttng_write_event_header
 206  *
 207  * Writes the event header to the offset (already aligned on 32-bits).
 208  *
 209  * @config: ring buffer instance configuration
 210  * @ctx: reservation context
 211  * @event_id: event ID
 212  */
 213 static __inline__
 214 void lttng_write_event_header(const struct lttng_ust_ring_buffer_config *config,
 215                             struct lttng_ust_ring_buffer_ctx *ctx,
 216                             struct lttng_client_ctx *client_ctx,
 217                             uint32_t event_id)
 218 {
 219         struct lttng_ust_channel_buffer *lttng_chan = channel_get_private(ctx->priv->chan);
 220
 221         if (caa_unlikely(ctx->priv->rflags))
 222                 goto slow_path;
 223
 224         switch (lttng_chan->priv->header_type) {
 225         case 1: /* compact */
 226         {
 227                 uint32_t id_time = 0;
 228
 229                 bt_bitfield_write(&id_time, uint32_t,
 230                                 0,
 231                                 LTTNG_COMPACT_EVENT_BITS,
 232                                 event_id);
 233                 bt_bitfield_write(&id_time, uint32_t,
 234                                 LTTNG_COMPACT_EVENT_BITS,
 235                                 LTTNG_COMPACT_TIMESTAMP_BITS,
 236                                 ctx->priv->timestamp);
 237                 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 238                 break;
 239         }
 240         case 2: /* large */
 241         {
 242                 uint32_t timestamp = (uint32_t) ctx->priv->timestamp;
 243                 uint16_t id = event_id;
 244
 245                 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 246                 lttng_ust_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(uint32_t));
 247                 lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 248                 break;
 249         }
 250         default:
 251                 WARN_ON_ONCE(1);
 252         }
 253
 254         ctx_record(ctx, lttng_chan, client_ctx->chan_ctx);
 255         lttng_ust_ring_buffer_align_ctx(ctx, ctx->largest_align);
 256
 257         return;
 258
 259 slow_path:
 260         lttng_write_event_header_slow(config, ctx, client_ctx, event_id);
 261 }
 262
 263 static
 264 void lttng_write_event_header_slow(const struct lttng_ust_ring_buffer_config *config,
 265                                  struct lttng_ust_ring_buffer_ctx *ctx,
 266                                  struct lttng_client_ctx *client_ctx,
 267                                  uint32_t event_id)
 268 {
 269         struct lttng_ust_ring_buffer_ctx_private *ctx_private = ctx->priv;
 270         struct lttng_ust_channel_buffer *lttng_chan = channel_get_private(ctx->priv->chan);
 271
 272         switch (lttng_chan->priv->header_type) {
 273         case 1: /* compact */
 274                 if (!(ctx_private->rflags & (RING_BUFFER_RFLAG_FULL_TIMESTAMP | LTTNG_RFLAG_EXTENDED))) {
 275                         uint32_t id_time = 0;
 276
 277                         bt_bitfield_write(&id_time, uint32_t,
 278                                         0,
 279                                         LTTNG_COMPACT_EVENT_BITS,
 280                                         event_id);
 281                         bt_bitfield_write(&id_time, uint32_t,
 282                                         LTTNG_COMPACT_EVENT_BITS,
 283                                         LTTNG_COMPACT_TIMESTAMP_BITS,
 284                                         ctx_private->timestamp);
 285                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 286                 } else {
 287                         uint8_t id = 0;
 288                         uint64_t timestamp = ctx_private->timestamp;
 289
 290                         bt_bitfield_write(&id, uint8_t,
 291                                         0,
 292                                         LTTNG_COMPACT_EVENT_BITS,
 293                                         31);
 294                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 295                         /* Align extended struct on largest member */
 296                         lttng_ust_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(uint64_t));
 297                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 298                         lttng_ust_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(uint64_t));
 299                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 300                 }
 301                 break;
 302         case 2: /* large */
 303         {
 304                 if (!(ctx_private->rflags & (RING_BUFFER_RFLAG_FULL_TIMESTAMP | LTTNG_RFLAG_EXTENDED))) {
 305                         uint32_t timestamp = (uint32_t) ctx_private->timestamp;
 306                         uint16_t id = event_id;
 307
 308                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 309                         lttng_ust_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(uint32_t));
 310                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 311                 } else {
 312                         uint16_t id = 65535;
 313                         uint64_t timestamp = ctx_private->timestamp;
 314
 315                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 316                         /* Align extended struct on largest member */
 317                         lttng_ust_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(uint64_t));
 318                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 319                         lttng_ust_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(uint64_t));
 320                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 321                 }
 322                 break;
 323         }
 324         default:
 325                 WARN_ON_ONCE(1);
 326         }
 327         ctx_record(ctx, lttng_chan, client_ctx->chan_ctx);
 328         lttng_ust_ring_buffer_align_ctx(ctx, ctx->largest_align);
 329 }
 330
 331 static const struct lttng_ust_ring_buffer_config client_config;
 332
 333 static uint64_t client_ring_buffer_clock_read(struct lttng_ust_ring_buffer_channel *chan)
 334 {
 335         return lib_ring_buffer_clock_read(chan);
 336 }
 337
 338 static
 339 size_t client_record_header_size(const struct lttng_ust_ring_buffer_config *config,
 340                                  struct lttng_ust_ring_buffer_channel *chan,
 341                                  size_t offset,
 342                                  size_t *pre_header_padding,
 343                                  struct lttng_ust_ring_buffer_ctx *ctx,
 344                                  void *client_ctx)
 345 {
 346         return record_header_size(config, chan, offset,
 347                                   pre_header_padding, ctx, client_ctx);
 348 }
 349
 350 /**
 351  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 352  *
 353  * Return header size without padding after the structure. Don't use packed
 354  * structure because gcc generates inefficient code on some architectures
 355  * (powerpc, mips..)
 356  */
 357 static size_t client_packet_header_size(void)
 358 {
 359         return offsetof(struct packet_header, ctx.header_end);
 360 }
 361
 362 static void client_buffer_begin(struct lttng_ust_ring_buffer *buf, uint64_t timestamp,
 363                                 unsigned int subbuf_idx,
 364                                 struct lttng_ust_shm_handle *handle)
 365 {
 366         struct lttng_ust_ring_buffer_channel *chan = shmp(handle, buf->backend.chan);
 367         struct packet_header *header =
 368                 (struct packet_header *)
 369                         lib_ring_buffer_offset_address(&buf->backend,
 370                                 subbuf_idx * chan->backend.subbuf_size,
 371                                 handle);
 372         struct lttng_ust_channel_buffer *lttng_chan = channel_get_private(chan);
 373         uint64_t cnt = shmp_index(handle, buf->backend.buf_cnt, subbuf_idx)->seq_cnt;
 374
 375         assert(header);
 376         if (!header)
 377                 return;
 378         header->magic = CTF_MAGIC_NUMBER;
 379         memcpy(header->uuid, lttng_chan->priv->uuid, sizeof(lttng_chan->priv->uuid));
 380         header->stream_id = lttng_chan->priv->id;
 381         header->stream_instance_id = buf->backend.cpu;
 382         header->ctx.timestamp_begin = timestamp;
 383         header->ctx.timestamp_end = 0;
 384         header->ctx.content_size = ~0ULL; /* for debugging */
 385         header->ctx.packet_size = ~0ULL;
 386         header->ctx.packet_seq_num = chan->backend.num_subbuf * cnt + subbuf_idx;
 387         header->ctx.events_discarded = 0;
 388         header->ctx.cpu_id = buf->backend.cpu;
 389 }
 390
 391 /*
 392  * offset is assumed to never be 0 here : never deliver a completely empty
 393  * subbuffer. data_size is between 1 and subbuf_size.
 394  */
 395 static void client_buffer_end(struct lttng_ust_ring_buffer *buf, uint64_t timestamp,
 396                               unsigned int subbuf_idx, unsigned long data_size,
 397                               struct lttng_ust_shm_handle *handle,
 398                               const struct lttng_ust_ring_buffer_ctx *ctx)
 399 {
 400         struct lttng_ust_ring_buffer_channel *chan = shmp(handle, buf->backend.chan);
 401         struct packet_header *header =
 402                 (struct packet_header *)
 403                         lib_ring_buffer_offset_address(&buf->backend,
 404                                 subbuf_idx * chan->backend.subbuf_size,
 405                                 handle);
 406         unsigned long records_lost = 0;
 407
 408         assert(header);
 409         if (!header)
 410                 return;
 411         header->ctx.timestamp_end = timestamp;
 412         header->ctx.content_size =
 413                 (uint64_t) data_size * CHAR_BIT;                /* in bits */
 414         header->ctx.packet_size =
 415                 (uint64_t) LTTNG_UST_PAGE_ALIGN(data_size) * CHAR_BIT;  /* in bits */
 416
 417         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, ctx);
 418         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, ctx);
 419         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, ctx);
 420         header->ctx.events_discarded = records_lost;
 421 }
 422
 423 static int client_buffer_create(
 424                 struct lttng_ust_ring_buffer *buf __attribute__((unused)),
 425                 void *priv __attribute__((unused)),
 426                 int cpu __attribute__((unused)),
 427                 const char *name __attribute__((unused)),
 428                 struct lttng_ust_shm_handle *handle __attribute__((unused)))
 429 {
 430         return 0;
 431 }
 432
 433 static void client_buffer_finalize(
 434                 struct lttng_ust_ring_buffer *buf __attribute__((unused)),
 435                 void *priv __attribute__((unused)),
 436                 int cpu __attribute__((unused)),
 437                 struct lttng_ust_shm_handle *handle __attribute__((unused)))
 438 {
 439 }
 440
 441 static void client_content_size_field(
 442                 const struct lttng_ust_ring_buffer_config *config __attribute__((unused)),
 443                 size_t *offset, size_t *length)
 444 {
 445         *offset = offsetof(struct packet_header, ctx.content_size);
 446         *length = sizeof(((struct packet_header *) NULL)->ctx.content_size);
 447 }
 448
 449 static void client_packet_size_field(
 450                 const struct lttng_ust_ring_buffer_config *config __attribute__((unused)),
 451                 size_t *offset, size_t *length)
 452 {
 453         *offset = offsetof(struct packet_header, ctx.packet_size);
 454         *length = sizeof(((struct packet_header *) NULL)->ctx.packet_size);
 455 }
 456
 457 static struct packet_header *client_packet_header(struct lttng_ust_ring_buffer *buf,
 458                 struct lttng_ust_shm_handle *handle)
 459 {
 460         return lib_ring_buffer_read_offset_address(&buf->backend, 0, handle);
 461 }
 462
 463 static int client_timestamp_begin(struct lttng_ust_ring_buffer *buf,
 464                 struct lttng_ust_ring_buffer_channel *chan,
 465                 uint64_t *timestamp_begin)
 466 {
 467         struct lttng_ust_shm_handle *handle = chan->handle;
 468         struct packet_header *header;
 469
 470         header = client_packet_header(buf, handle);
 471         if (!header)
 472                 return -1;
 473         *timestamp_begin = header->ctx.timestamp_begin;
 474         return 0;
 475 }
 476
 477 static int client_timestamp_end(struct lttng_ust_ring_buffer *buf,
 478                 struct lttng_ust_ring_buffer_channel *chan,
 479                 uint64_t *timestamp_end)
 480 {
 481         struct lttng_ust_shm_handle *handle = chan->handle;
 482         struct packet_header *header;
 483
 484         header = client_packet_header(buf, handle);
 485         if (!header)
 486                 return -1;
 487         *timestamp_end = header->ctx.timestamp_end;
 488         return 0;
 489 }
 490
 491 static int client_events_discarded(struct lttng_ust_ring_buffer *buf,
 492                 struct lttng_ust_ring_buffer_channel *chan,
 493                 uint64_t *events_discarded)
 494 {
 495         struct lttng_ust_shm_handle *handle = chan->handle;
 496         struct packet_header *header;
 497
 498         header = client_packet_header(buf, handle);
 499         if (!header)
 500                 return -1;
 501         *events_discarded = header->ctx.events_discarded;
 502         return 0;
 503 }
 504
 505 static int client_content_size(struct lttng_ust_ring_buffer *buf,
 506                 struct lttng_ust_ring_buffer_channel *chan,
 507                 uint64_t *content_size)
 508 {
 509         struct lttng_ust_shm_handle *handle = chan->handle;
 510         struct packet_header *header;
 511
 512         header = client_packet_header(buf, handle);
 513         if (!header)
 514                 return -1;
 515         *content_size = header->ctx.content_size;
 516         return 0;
 517 }
 518
 519 static int client_packet_size(struct lttng_ust_ring_buffer *buf,
 520                 struct lttng_ust_ring_buffer_channel *chan,
 521                 uint64_t *packet_size)
 522 {
 523         struct lttng_ust_shm_handle *handle = chan->handle;
 524         struct packet_header *header;
 525
 526         header = client_packet_header(buf, handle);
 527         if (!header)
 528                 return -1;
 529         *packet_size = header->ctx.packet_size;
 530         return 0;
 531 }
 532
 533 static int client_stream_id(struct lttng_ust_ring_buffer *buf __attribute__((unused)),
 534                 struct lttng_ust_ring_buffer_channel *chan,
 535                 uint64_t *stream_id)
 536 {
 537         struct lttng_ust_channel_buffer *lttng_chan = channel_get_private(chan);
 538
 539         *stream_id = lttng_chan->priv->id;
 540
 541         return 0;
 542 }
 543
 544 static int client_current_timestamp(
 545                 struct lttng_ust_ring_buffer *buf  __attribute__((unused)),
 546                 struct lttng_ust_ring_buffer_channel *chan,
 547                 uint64_t *ts)
 548 {
 549         *ts = client_ring_buffer_clock_read(chan);
 550
 551         return 0;
 552 }
 553
 554 static int client_sequence_number(struct lttng_ust_ring_buffer *buf,
 555                 struct lttng_ust_ring_buffer_channel *chan,
 556                 uint64_t *seq)
 557 {
 558         struct lttng_ust_shm_handle *handle = chan->handle;
 559         struct packet_header *header;
 560
 561         header = client_packet_header(buf, handle);
 562         if (!header)
 563                 return -1;
 564         *seq = header->ctx.packet_seq_num;
 565         return 0;
 566 }
 567
 568 static int client_instance_id(struct lttng_ust_ring_buffer *buf,
 569                 struct lttng_ust_ring_buffer_channel *chan __attribute__((unused)),
 570                 uint64_t *id)
 571 {
 572         *id = buf->backend.cpu;
 573
 574         return 0;
 575 }
 576
 577 static const
 578 struct lttng_ust_client_lib_ring_buffer_client_cb client_cb = {
 579         .parent = {
 580                 .ring_buffer_clock_read = client_ring_buffer_clock_read,
 581                 .record_header_size = client_record_header_size,
 582                 .subbuffer_header_size = client_packet_header_size,
 583                 .buffer_begin = client_buffer_begin,
 584                 .buffer_end = client_buffer_end,
 585                 .buffer_create = client_buffer_create,
 586                 .buffer_finalize = client_buffer_finalize,
 587                 .content_size_field = client_content_size_field,
 588                 .packet_size_field = client_packet_size_field,
 589         },
 590         .timestamp_begin = client_timestamp_begin,
 591         .timestamp_end = client_timestamp_end,
 592         .events_discarded = client_events_discarded,
 593         .content_size = client_content_size,
 594         .packet_size = client_packet_size,
 595         .stream_id = client_stream_id,
 596         .current_timestamp = client_current_timestamp,
 597         .sequence_number = client_sequence_number,
 598         .instance_id = client_instance_id,
 599 };
 600
 601 static const struct lttng_ust_ring_buffer_config client_config = {
 602         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 603         .cb.record_header_size = client_record_header_size,
 604         .cb.subbuffer_header_size = client_packet_header_size,
 605         .cb.buffer_begin = client_buffer_begin,
 606         .cb.buffer_end = client_buffer_end,
 607         .cb.buffer_create = client_buffer_create,
 608         .cb.buffer_finalize = client_buffer_finalize,
 609         .cb.content_size_field = client_content_size_field,
 610         .cb.packet_size_field = client_packet_size_field,
 611
 612         .timestamp_bits = LTTNG_COMPACT_TIMESTAMP_BITS,
 613         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 614         .sync = RING_BUFFER_SYNC_GLOBAL,
 615         .mode = RING_BUFFER_MODE_TEMPLATE,
 616         .backend = RING_BUFFER_PAGE,
 617         .output = RING_BUFFER_MMAP,
 618         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 619         .ipi = RING_BUFFER_NO_IPI_BARRIER,
 620         .wakeup = LTTNG_CLIENT_WAKEUP,
 621         .client_type = LTTNG_CLIENT_TYPE,
 622
 623         .cb_ptr = &client_cb.parent,
 624 };
 625
 626 static
 627 struct lttng_ust_channel_buffer *_channel_create(const char *name,
 628                                 void *buf_addr,
 629                                 size_t subbuf_size, size_t num_subbuf,
 630                                 unsigned int switch_timer_interval,
 631                                 unsigned int read_timer_interval,
 632                                 unsigned char *uuid,
 633                                 uint32_t chan_id,
 634                                 const int *stream_fds, int nr_stream_fds,
 635                                 int64_t blocking_timeout)
 636 {
 637         struct lttng_ust_abi_channel_config chan_priv_init;
 638         struct lttng_ust_shm_handle *handle;
 639         struct lttng_ust_channel_buffer *lttng_chan_buf;
 640
 641         lttng_chan_buf = lttng_ust_alloc_channel_buffer();
 642         if (!lttng_chan_buf)
 643                 return NULL;
 644         memcpy(lttng_chan_buf->priv->uuid, uuid, LTTNG_UST_UUID_LEN);
 645         lttng_chan_buf->priv->id = chan_id;
 646
 647         memset(&chan_priv_init, 0, sizeof(chan_priv_init));
 648         memcpy(chan_priv_init.uuid, uuid, LTTNG_UST_UUID_LEN);
 649         chan_priv_init.id = chan_id;
 650
 651         handle = channel_create(&client_config, name,
 652                         __alignof__(struct lttng_ust_abi_channel_config),
 653                         sizeof(struct lttng_ust_abi_channel_config),
 654                         &chan_priv_init,
 655                         lttng_chan_buf, buf_addr, subbuf_size, num_subbuf,
 656                         switch_timer_interval, read_timer_interval,
 657                         stream_fds, nr_stream_fds, blocking_timeout);
 658         if (!handle)
 659                 goto error;
 660         lttng_chan_buf->priv->rb_chan = shmp(handle, handle->chan);
 661         return lttng_chan_buf;
 662
 663 error:
 664         lttng_ust_free_channel_common(lttng_chan_buf->parent);
 665         return NULL;
 666 }
 667
 668 static
 669 void lttng_channel_destroy(struct lttng_ust_channel_buffer *lttng_chan_buf)
 670 {
 671         channel_destroy(lttng_chan_buf->priv->rb_chan, lttng_chan_buf->priv->rb_chan->handle, 1);
 672         lttng_ust_free_channel_common(lttng_chan_buf->parent);
 673 }
 674
 675 static
 676 int lttng_event_reserve(struct lttng_ust_ring_buffer_ctx *ctx)
 677 {
 678         struct lttng_ust_event_recorder *event_recorder = ctx->client_priv;
 679         struct lttng_ust_channel_buffer *lttng_chan = event_recorder->chan;
 680         struct lttng_client_ctx client_ctx;
 681         int ret, nesting;
 682         struct lttng_ust_ring_buffer_ctx_private *private_ctx;
 683         uint32_t event_id;
 684
 685         event_id = (uint32_t) event_recorder->priv->parent.id;
 686         client_ctx.chan_ctx = lttng_ust_rcu_dereference(lttng_chan->priv->ctx);
 687         /* Compute internal size of context structures. */
 688         ctx_get_struct_size(ctx, client_ctx.chan_ctx, &client_ctx.packet_context_len);
 689
 690         nesting = lib_ring_buffer_nesting_inc(&client_config);
 691         if (nesting < 0)
 692                 return -EPERM;
 693
 694         private_ctx = &URCU_TLS(private_ctx_stack)[nesting];
 695         memset(private_ctx, 0, sizeof(*private_ctx));
 696         private_ctx->pub = ctx;
 697         private_ctx->chan = lttng_chan->priv->rb_chan;
 698
 699         ctx->priv = private_ctx;
 700
 701         switch (lttng_chan->priv->header_type) {
 702         case 1: /* compact */
 703                 if (event_id > 30)
 704                         private_ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 705                 break;
 706         case 2: /* large */
 707                 if (event_id > 65534)
 708                         private_ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 709                 break;
 710         default:
 711                 WARN_ON_ONCE(1);
 712         }
 713
 714         ret = lib_ring_buffer_reserve(&client_config, ctx, &client_ctx);
 715         if (caa_unlikely(ret))
 716                 goto put;
 717         if (lib_ring_buffer_backend_get_pages(&client_config, ctx,
 718                         &private_ctx->backend_pages)) {
 719                 ret = -EPERM;
 720                 goto put;
 721         }
 722         lttng_write_event_header(&client_config, ctx, &client_ctx, event_id);
 723         return 0;
 724 put:
 725         lib_ring_buffer_nesting_dec(&client_config);
 726         return ret;
 727 }
 728
 729 static
 730 void lttng_event_commit(struct lttng_ust_ring_buffer_ctx *ctx)
 731 {
 732         lib_ring_buffer_commit(&client_config, ctx);
 733         lib_ring_buffer_nesting_dec(&client_config);
 734 }
 735
 736 static
 737 void lttng_event_write(struct lttng_ust_ring_buffer_ctx *ctx,
 738                 const void *src, size_t len, size_t alignment)
 739 {
 740         lttng_ust_ring_buffer_align_ctx(ctx, alignment);
 741         lib_ring_buffer_write(&client_config, ctx, src, len);
 742 }
 743
 744 static
 745 void lttng_event_strcpy(struct lttng_ust_ring_buffer_ctx *ctx,
 746                 const char *src, size_t len)
 747 {
 748         lib_ring_buffer_strcpy(&client_config, ctx, src, len, '#');
 749 }
 750
 751 static
 752 void lttng_event_pstrcpy_pad(struct lttng_ust_ring_buffer_ctx *ctx,
 753                 const char *src, size_t len)
 754 {
 755         lib_ring_buffer_pstrcpy(&client_config, ctx, src, len, '\0');
 756 }
 757
 758 static
 759 int lttng_is_finalized(struct lttng_ust_channel_buffer *chan)
 760 {
 761         struct lttng_ust_ring_buffer_channel *rb_chan = chan->priv->rb_chan;
 762
 763         return lib_ring_buffer_channel_is_finalized(rb_chan);
 764 }
 765
 766 static
 767 int lttng_is_disabled(struct lttng_ust_channel_buffer *chan)
 768 {
 769         struct lttng_ust_ring_buffer_channel *rb_chan = chan->priv->rb_chan;
 770
 771         return lib_ring_buffer_channel_is_disabled(rb_chan);
 772 }
 773
 774 static
 775 int lttng_flush_buffer(struct lttng_ust_channel_buffer *chan)
 776 {
 777         struct lttng_ust_ring_buffer_channel *rb_chan = chan->priv->rb_chan;
 778         struct lttng_ust_ring_buffer *buf;
 779         int cpu;
 780
 781         for_each_channel_cpu(cpu, rb_chan) {
 782                 int shm_fd, wait_fd, wakeup_fd;
 783                 uint64_t memory_map_size;
 784                 void *memory_map_addr;
 785
 786                 buf = channel_get_ring_buffer(&client_config, rb_chan,
 787                                 cpu, rb_chan->handle, &shm_fd, &wait_fd,
 788                                 &wakeup_fd, &memory_map_size, &memory_map_addr);
 789                 lib_ring_buffer_switch(&client_config, buf,
 790                                 SWITCH_ACTIVE, rb_chan->handle);
 791         }
 792         return 0;
 793 }
 794
 795 static struct lttng_transport lttng_relay_transport = {
 796         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap",
 797         .ops = {
 798                 .struct_size = sizeof(struct lttng_ust_channel_buffer_ops),
 799                 .priv = LTTNG_UST_COMPOUND_LITERAL(struct lttng_ust_channel_buffer_ops_private, {
 800                         .pub = &lttng_relay_transport.ops,
 801                         .channel_create = _channel_create,
 802                         .channel_destroy = lttng_channel_destroy,
 803                         .packet_avail_size = NULL,      /* Would be racy anyway */
 804                         .is_finalized = lttng_is_finalized,
 805                         .is_disabled = lttng_is_disabled,
 806                         .flush_buffer = lttng_flush_buffer,
 807                 }),
 808                 .event_reserve = lttng_event_reserve,
 809                 .event_commit = lttng_event_commit,
 810                 .event_write = lttng_event_write,
 811                 .event_strcpy = lttng_event_strcpy,
 812                 .event_pstrcpy_pad = lttng_event_pstrcpy_pad,
 813         },
 814         .client_config = &client_config,
 815 };
 816
 817 void RING_BUFFER_MODE_TEMPLATE_INIT(void)
 818 {
 819         DBG("LTT : ltt ring buffer client \"%s\" init\n",
 820                 "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap");
 821         lttng_transport_register(&lttng_relay_transport);
 822 }
 823
 824 void RING_BUFFER_MODE_TEMPLATE_EXIT(void)
 825 {
 826         DBG("LTT : ltt ring buffer client \"%s\" exit\n",
 827                 "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap");
 828         lttng_transport_unregister(&lttng_relay_transport);
 829 }