liblttng-ust/lttng-ring-buffer-client.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 <ust-events-internal.h>
  14 #include <lttng/urcu/pointer.h>
  15 #include "ust-bitfield.h"
  16 #include "ust-compat.h"
  17 #include "clock.h"
  18 #include "context-internal.h"
  19 #include "lttng-tracer.h"
  20 #include "../libringbuffer/frontend_types.h"
  21 #include <urcu/tls-compat.h>
  22
  23 #define LTTNG_COMPACT_EVENT_BITS       5
  24 #define LTTNG_COMPACT_TSC_BITS         27
  25
  26 enum app_ctx_mode {
  27         APP_CTX_DISABLED,
  28         APP_CTX_ENABLED,
  29 };
  30
  31 /*
  32  * Keep the natural field alignment for _each field_ within this structure if
  33  * you ever add/remove a field from this header. Packed attribute is not used
  34  * because gcc generates poor code on at least powerpc and mips. Don't ever
  35  * let gcc add padding between the structure elements.
  36  */
  37
  38 struct packet_header {
  39         /* Trace packet header */
  40         uint32_t magic;                 /*
  41                                          * Trace magic number.
  42                                          * contains endianness information.
  43                                          */
  44         uint8_t uuid[LTTNG_UST_UUID_LEN];
  45         uint32_t stream_id;
  46         uint64_t stream_instance_id;
  47
  48         struct {
  49                 /* Stream packet context */
  50                 uint64_t timestamp_begin;       /* Cycle count at subbuffer start */
  51                 uint64_t timestamp_end;         /* Cycle count at subbuffer end */
  52                 uint64_t content_size;          /* Size of data in subbuffer */
  53                 uint64_t packet_size;           /* Subbuffer size (include padding) */
  54                 uint64_t packet_seq_num;        /* Packet sequence number */
  55                 unsigned long events_discarded; /*
  56                                                  * Events lost in this subbuffer since
  57                                                  * the beginning of the trace.
  58                                                  * (may overflow)
  59                                                  */
  60                 uint32_t cpu_id;                /* CPU id associated with stream */
  61                 uint8_t header_end;             /* End of header */
  62         } ctx;
  63 };
  64
  65 struct lttng_client_ctx {
  66         size_t packet_context_len;
  67         size_t event_context_len;
  68         struct lttng_ust_ctx *chan_ctx;
  69         struct lttng_ust_ctx *event_ctx;
  70 };
  71
  72 /*
  73  * Indexed by lib_ring_buffer_nesting_count().
  74  */
  75 typedef struct lttng_ust_lib_ring_buffer_ctx_private private_ctx_stack_t[LIB_RING_BUFFER_MAX_NESTING];
  76 static DEFINE_URCU_TLS(private_ctx_stack_t, private_ctx_stack);
  77
  78 /*
  79  * Force a read (imply TLS fixup for dlopen) of TLS variables.
  80  */
  81 static
  82 void lttng_fixup_rb_client_tls(void)
  83 {
  84         asm volatile ("" : : "m" (URCU_TLS(private_ctx_stack)));
  85 }
  86
  87 static inline uint64_t lib_ring_buffer_clock_read(struct lttng_ust_lib_ring_buffer_channel *chan)
  88 {
  89         return trace_clock_read64();
  90 }
  91
  92 static inline
  93 size_t ctx_get_aligned_size(size_t offset, struct lttng_ust_ctx *ctx,
  94                 size_t ctx_len)
  95 {
  96         size_t orig_offset = offset;
  97
  98         if (caa_likely(!ctx))
  99                 return 0;
 100         offset += lttng_ust_lib_ring_buffer_align(offset, ctx->largest_align);
 101         offset += ctx_len;
 102         return offset - orig_offset;
 103 }
 104
 105 static inline
 106 void ctx_get_struct_size(struct lttng_ust_ctx *ctx, size_t *ctx_len,
 107                 enum app_ctx_mode mode)
 108 {
 109         int i;
 110         size_t offset = 0;
 111
 112         if (caa_likely(!ctx)) {
 113                 *ctx_len = 0;
 114                 return;
 115         }
 116         for (i = 0; i < ctx->nr_fields; i++) {
 117                 if (mode == APP_CTX_ENABLED) {
 118                         offset += ctx->fields[i]->get_size(ctx->fields[i], offset);
 119                 } else {
 120                         if (lttng_context_is_app(ctx->fields[i]->event_field->name)) {
 121                                 /*
 122                                  * Before UST 2.8, we cannot use the
 123                                  * application context, because we
 124                                  * cannot trust that the handler used
 125                                  * for get_size is the same used for
 126                                  * ctx_record, which would result in
 127                                  * corrupted traces when tracing
 128                                  * concurrently with application context
 129                                  * register/unregister.
 130                                  */
 131                                 offset += lttng_ust_dummy_get_size(ctx->fields[i], offset);
 132                         } else {
 133                                 offset += ctx->fields[i]->get_size(ctx->fields[i], offset);
 134                         }
 135                 }
 136         }
 137         *ctx_len = offset;
 138 }
 139
 140 static inline
 141 void ctx_record(struct lttng_ust_lib_ring_buffer_ctx *bufctx,
 142                 struct lttng_ust_channel_buffer *chan,
 143                 struct lttng_ust_ctx *ctx,
 144                 enum app_ctx_mode mode)
 145 {
 146         int i;
 147
 148         if (caa_likely(!ctx))
 149                 return;
 150         lttng_ust_lib_ring_buffer_align_ctx(bufctx, ctx->largest_align);
 151         for (i = 0; i < ctx->nr_fields; i++) {
 152                 if (mode == APP_CTX_ENABLED) {
 153                         ctx->fields[i]->record(ctx->fields[i], bufctx, chan);
 154                 } else {
 155                         if (lttng_context_is_app(ctx->fields[i]->event_field->name)) {
 156                                 /*
 157                                  * Before UST 2.8, we cannot use the
 158                                  * application context, because we
 159                                  * cannot trust that the handler used
 160                                  * for get_size is the same used for
 161                                  * ctx_record, which would result in
 162                                  * corrupted traces when tracing
 163                                  * concurrently with application context
 164                                  * register/unregister.
 165                                  */
 166                                 lttng_ust_dummy_record(ctx->fields[i], bufctx, chan);
 167                         } else {
 168                                 ctx->fields[i]->record(ctx->fields[i], bufctx, chan);
 169                         }
 170                 }
 171         }
 172 }
 173
 174 /*
 175  * record_header_size - Calculate the header size and padding necessary.
 176  * @config: ring buffer instance configuration
 177  * @chan: channel
 178  * @offset: offset in the write buffer
 179  * @pre_header_padding: padding to add before the header (output)
 180  * @ctx: reservation context
 181  *
 182  * Returns the event header size (including padding).
 183  *
 184  * The payload must itself determine its own alignment from the biggest type it
 185  * contains.
 186  */
 187 static __inline__
 188 size_t record_header_size(const struct lttng_ust_lib_ring_buffer_config *config,
 189                                  struct lttng_ust_lib_ring_buffer_channel *chan,
 190                                  size_t offset,
 191                                  size_t *pre_header_padding,
 192                                  struct lttng_ust_lib_ring_buffer_ctx *ctx,
 193                                  struct lttng_client_ctx *client_ctx)
 194 {
 195         struct lttng_ust_channel_buffer *lttng_chan = channel_get_private(chan);
 196         size_t orig_offset = offset;
 197         size_t padding;
 198
 199         switch (lttng_chan->priv->header_type) {
 200         case 1: /* compact */
 201                 padding = lttng_ust_lib_ring_buffer_align(offset, lttng_ust_rb_alignof(uint32_t));
 202                 offset += padding;
 203                 if (!(ctx->priv->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 204                         offset += sizeof(uint32_t);     /* id and timestamp */
 205                 } else {
 206                         /* Minimum space taken by LTTNG_COMPACT_EVENT_BITS id */
 207                         offset += (LTTNG_COMPACT_EVENT_BITS + CHAR_BIT - 1) / CHAR_BIT;
 208                         /* Align extended struct on largest member */
 209                         offset += lttng_ust_lib_ring_buffer_align(offset, lttng_ust_rb_alignof(uint64_t));
 210                         offset += sizeof(uint32_t);     /* id */
 211                         offset += lttng_ust_lib_ring_buffer_align(offset, lttng_ust_rb_alignof(uint64_t));
 212                         offset += sizeof(uint64_t);     /* timestamp */
 213                 }
 214                 break;
 215         case 2: /* large */
 216                 padding = lttng_ust_lib_ring_buffer_align(offset, lttng_ust_rb_alignof(uint16_t));
 217                 offset += padding;
 218                 offset += sizeof(uint16_t);
 219                 if (!(ctx->priv->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 220                         offset += lttng_ust_lib_ring_buffer_align(offset, lttng_ust_rb_alignof(uint32_t));
 221                         offset += sizeof(uint32_t);     /* timestamp */
 222                 } else {
 223                         /* Align extended struct on largest member */
 224                         offset += lttng_ust_lib_ring_buffer_align(offset, lttng_ust_rb_alignof(uint64_t));
 225                         offset += sizeof(uint32_t);     /* id */
 226                         offset += lttng_ust_lib_ring_buffer_align(offset, lttng_ust_rb_alignof(uint64_t));
 227                         offset += sizeof(uint64_t);     /* timestamp */
 228                 }
 229                 break;
 230         default:
 231                 padding = 0;
 232                 WARN_ON_ONCE(1);
 233         }
 234         offset += ctx_get_aligned_size(offset, client_ctx->chan_ctx,
 235                         client_ctx->packet_context_len);
 236         offset += ctx_get_aligned_size(offset, client_ctx->event_ctx,
 237                         client_ctx->event_context_len);
 238         *pre_header_padding = padding;
 239         return offset - orig_offset;
 240 }
 241
 242 #include "../libringbuffer/api.h"
 243 #include "lttng-rb-clients.h"
 244
 245 static
 246 void lttng_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config *config,
 247                                  struct lttng_ust_lib_ring_buffer_ctx *ctx,
 248                                  struct lttng_client_ctx *client_ctx,
 249                                  uint32_t event_id);
 250
 251 /*
 252  * lttng_write_event_header
 253  *
 254  * Writes the event header to the offset (already aligned on 32-bits).
 255  *
 256  * @config: ring buffer instance configuration
 257  * @ctx: reservation context
 258  * @event_id: event ID
 259  */
 260 static __inline__
 261 void lttng_write_event_header(const struct lttng_ust_lib_ring_buffer_config *config,
 262                             struct lttng_ust_lib_ring_buffer_ctx *ctx,
 263                             struct lttng_client_ctx *client_ctx,
 264                             uint32_t event_id)
 265 {
 266         struct lttng_ust_channel_buffer *lttng_chan = channel_get_private(ctx->priv->chan);
 267
 268         if (caa_unlikely(ctx->priv->rflags))
 269                 goto slow_path;
 270
 271         switch (lttng_chan->priv->header_type) {
 272         case 1: /* compact */
 273         {
 274                 uint32_t id_time = 0;
 275
 276                 bt_bitfield_write(&id_time, uint32_t,
 277                                 0,
 278                                 LTTNG_COMPACT_EVENT_BITS,
 279                                 event_id);
 280                 bt_bitfield_write(&id_time, uint32_t,
 281                                 LTTNG_COMPACT_EVENT_BITS,
 282                                 LTTNG_COMPACT_TSC_BITS,
 283                                 ctx->priv->tsc);
 284                 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 285                 break;
 286         }
 287         case 2: /* large */
 288         {
 289                 uint32_t timestamp = (uint32_t) ctx->priv->tsc;
 290                 uint16_t id = event_id;
 291
 292                 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 293                 lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(uint32_t));
 294                 lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 295                 break;
 296         }
 297         default:
 298                 WARN_ON_ONCE(1);
 299         }
 300
 301         ctx_record(ctx, lttng_chan, client_ctx->chan_ctx, APP_CTX_ENABLED);
 302         ctx_record(ctx, lttng_chan, client_ctx->event_ctx, APP_CTX_ENABLED);
 303         lttng_ust_lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 304
 305         return;
 306
 307 slow_path:
 308         lttng_write_event_header_slow(config, ctx, client_ctx, event_id);
 309 }
 310
 311 static
 312 void lttng_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config *config,
 313                                  struct lttng_ust_lib_ring_buffer_ctx *ctx,
 314                                  struct lttng_client_ctx *client_ctx,
 315                                  uint32_t event_id)
 316 {
 317         struct lttng_ust_lib_ring_buffer_ctx_private *ctx_private = ctx->priv;
 318         struct lttng_ust_channel_buffer *lttng_chan = channel_get_private(ctx->priv->chan);
 319
 320         switch (lttng_chan->priv->header_type) {
 321         case 1: /* compact */
 322                 if (!(ctx_private->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 323                         uint32_t id_time = 0;
 324
 325                         bt_bitfield_write(&id_time, uint32_t,
 326                                         0,
 327                                         LTTNG_COMPACT_EVENT_BITS,
 328                                         event_id);
 329                         bt_bitfield_write(&id_time, uint32_t,
 330                                         LTTNG_COMPACT_EVENT_BITS,
 331                                         LTTNG_COMPACT_TSC_BITS,
 332                                         ctx_private->tsc);
 333                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 334                 } else {
 335                         uint8_t id = 0;
 336                         uint64_t timestamp = ctx_private->tsc;
 337
 338                         bt_bitfield_write(&id, uint8_t,
 339                                         0,
 340                                         LTTNG_COMPACT_EVENT_BITS,
 341                                         31);
 342                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 343                         /* Align extended struct on largest member */
 344                         lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(uint64_t));
 345                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 346                         lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(uint64_t));
 347                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 348                 }
 349                 break;
 350         case 2: /* large */
 351         {
 352                 if (!(ctx_private->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 353                         uint32_t timestamp = (uint32_t) ctx_private->tsc;
 354                         uint16_t id = event_id;
 355
 356                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 357                         lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(uint32_t));
 358                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 359                 } else {
 360                         uint16_t id = 65535;
 361                         uint64_t timestamp = ctx_private->tsc;
 362
 363                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 364                         /* Align extended struct on largest member */
 365                         lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(uint64_t));
 366                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 367                         lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(uint64_t));
 368                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 369                 }
 370                 break;
 371         }
 372         default:
 373                 WARN_ON_ONCE(1);
 374         }
 375         ctx_record(ctx, lttng_chan, client_ctx->chan_ctx, APP_CTX_ENABLED);
 376         ctx_record(ctx, lttng_chan, client_ctx->event_ctx, APP_CTX_ENABLED);
 377         lttng_ust_lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 378 }
 379
 380 static const struct lttng_ust_lib_ring_buffer_config client_config;
 381
 382 static uint64_t client_ring_buffer_clock_read(struct lttng_ust_lib_ring_buffer_channel *chan)
 383 {
 384         return lib_ring_buffer_clock_read(chan);
 385 }
 386
 387 static
 388 size_t client_record_header_size(const struct lttng_ust_lib_ring_buffer_config *config,
 389                                  struct lttng_ust_lib_ring_buffer_channel *chan,
 390                                  size_t offset,
 391                                  size_t *pre_header_padding,
 392                                  struct lttng_ust_lib_ring_buffer_ctx *ctx,
 393                                  void *client_ctx)
 394 {
 395         return record_header_size(config, chan, offset,
 396                                   pre_header_padding, ctx, client_ctx);
 397 }
 398
 399 /**
 400  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 401  *
 402  * Return header size without padding after the structure. Don't use packed
 403  * structure because gcc generates inefficient code on some architectures
 404  * (powerpc, mips..)
 405  */
 406 static size_t client_packet_header_size(void)
 407 {
 408         return offsetof(struct packet_header, ctx.header_end);
 409 }
 410
 411 static void client_buffer_begin(struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
 412                                 unsigned int subbuf_idx,
 413                                 struct lttng_ust_shm_handle *handle)
 414 {
 415         struct lttng_ust_lib_ring_buffer_channel *chan = shmp(handle, buf->backend.chan);
 416         struct packet_header *header =
 417                 (struct packet_header *)
 418                         lib_ring_buffer_offset_address(&buf->backend,
 419                                 subbuf_idx * chan->backend.subbuf_size,
 420                                 handle);
 421         struct lttng_ust_channel_buffer *lttng_chan = channel_get_private(chan);
 422         uint64_t cnt = shmp_index(handle, buf->backend.buf_cnt, subbuf_idx)->seq_cnt;
 423
 424         assert(header);
 425         if (!header)
 426                 return;
 427         header->magic = CTF_MAGIC_NUMBER;
 428         memcpy(header->uuid, lttng_chan->priv->uuid, sizeof(lttng_chan->priv->uuid));
 429         header->stream_id = lttng_chan->priv->id;
 430         header->stream_instance_id = buf->backend.cpu;
 431         header->ctx.timestamp_begin = tsc;
 432         header->ctx.timestamp_end = 0;
 433         header->ctx.content_size = ~0ULL; /* for debugging */
 434         header->ctx.packet_size = ~0ULL;
 435         header->ctx.packet_seq_num = chan->backend.num_subbuf * cnt + subbuf_idx;
 436         header->ctx.events_discarded = 0;
 437         header->ctx.cpu_id = buf->backend.cpu;
 438 }
 439
 440 /*
 441  * offset is assumed to never be 0 here : never deliver a completely empty
 442  * subbuffer. data_size is between 1 and subbuf_size.
 443  */
 444 static void client_buffer_end(struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
 445                               unsigned int subbuf_idx, unsigned long data_size,
 446                               struct lttng_ust_shm_handle *handle)
 447 {
 448         struct lttng_ust_lib_ring_buffer_channel *chan = shmp(handle, buf->backend.chan);
 449         struct packet_header *header =
 450                 (struct packet_header *)
 451                         lib_ring_buffer_offset_address(&buf->backend,
 452                                 subbuf_idx * chan->backend.subbuf_size,
 453                                 handle);
 454         unsigned long records_lost = 0;
 455
 456         assert(header);
 457         if (!header)
 458                 return;
 459         header->ctx.timestamp_end = tsc;
 460         header->ctx.content_size =
 461                 (uint64_t) data_size * CHAR_BIT;                /* in bits */
 462         header->ctx.packet_size =
 463                 (uint64_t) LTTNG_UST_PAGE_ALIGN(data_size) * CHAR_BIT;  /* in bits */
 464
 465         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
 466         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 467         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 468         header->ctx.events_discarded = records_lost;
 469 }
 470
 471 static int client_buffer_create(struct lttng_ust_lib_ring_buffer *buf, void *priv,
 472                                 int cpu, const char *name, struct lttng_ust_shm_handle *handle)
 473 {
 474         return 0;
 475 }
 476
 477 static void client_buffer_finalize(struct lttng_ust_lib_ring_buffer *buf, void *priv, int cpu, struct lttng_ust_shm_handle *handle)
 478 {
 479 }
 480
 481 static void client_content_size_field(const struct lttng_ust_lib_ring_buffer_config *config,
 482                                       size_t *offset, size_t *length)
 483 {
 484         *offset = offsetof(struct packet_header, ctx.content_size);
 485         *length = sizeof(((struct packet_header *) NULL)->ctx.content_size);
 486 }
 487
 488 static void client_packet_size_field(const struct lttng_ust_lib_ring_buffer_config *config,
 489                                       size_t *offset, size_t *length)
 490 {
 491         *offset = offsetof(struct packet_header, ctx.packet_size);
 492         *length = sizeof(((struct packet_header *) NULL)->ctx.packet_size);
 493 }
 494
 495 static struct packet_header *client_packet_header(struct lttng_ust_lib_ring_buffer *buf,
 496                 struct lttng_ust_shm_handle *handle)
 497 {
 498         return lib_ring_buffer_read_offset_address(&buf->backend, 0, handle);
 499 }
 500
 501 static int client_timestamp_begin(struct lttng_ust_lib_ring_buffer *buf,
 502                 struct lttng_ust_lib_ring_buffer_channel *chan,
 503                 uint64_t *timestamp_begin)
 504 {
 505         struct lttng_ust_shm_handle *handle = chan->handle;
 506         struct packet_header *header;
 507
 508         header = client_packet_header(buf, handle);
 509         if (!header)
 510                 return -1;
 511         *timestamp_begin = header->ctx.timestamp_begin;
 512         return 0;
 513 }
 514
 515 static int client_timestamp_end(struct lttng_ust_lib_ring_buffer *buf,
 516                 struct lttng_ust_lib_ring_buffer_channel *chan,
 517                 uint64_t *timestamp_end)
 518 {
 519         struct lttng_ust_shm_handle *handle = chan->handle;
 520         struct packet_header *header;
 521
 522         header = client_packet_header(buf, handle);
 523         if (!header)
 524                 return -1;
 525         *timestamp_end = header->ctx.timestamp_end;
 526         return 0;
 527 }
 528
 529 static int client_events_discarded(struct lttng_ust_lib_ring_buffer *buf,
 530                 struct lttng_ust_lib_ring_buffer_channel *chan,
 531                 uint64_t *events_discarded)
 532 {
 533         struct lttng_ust_shm_handle *handle = chan->handle;
 534         struct packet_header *header;
 535
 536         header = client_packet_header(buf, handle);
 537         if (!header)
 538                 return -1;
 539         *events_discarded = header->ctx.events_discarded;
 540         return 0;
 541 }
 542
 543 static int client_content_size(struct lttng_ust_lib_ring_buffer *buf,
 544                 struct lttng_ust_lib_ring_buffer_channel *chan,
 545                 uint64_t *content_size)
 546 {
 547         struct lttng_ust_shm_handle *handle = chan->handle;
 548         struct packet_header *header;
 549
 550         header = client_packet_header(buf, handle);
 551         if (!header)
 552                 return -1;
 553         *content_size = header->ctx.content_size;
 554         return 0;
 555 }
 556
 557 static int client_packet_size(struct lttng_ust_lib_ring_buffer *buf,
 558                 struct lttng_ust_lib_ring_buffer_channel *chan,
 559                 uint64_t *packet_size)
 560 {
 561         struct lttng_ust_shm_handle *handle = chan->handle;
 562         struct packet_header *header;
 563
 564         header = client_packet_header(buf, handle);
 565         if (!header)
 566                 return -1;
 567         *packet_size = header->ctx.packet_size;
 568         return 0;
 569 }
 570
 571 static int client_stream_id(struct lttng_ust_lib_ring_buffer *buf,
 572                 struct lttng_ust_lib_ring_buffer_channel *chan,
 573                 uint64_t *stream_id)
 574 {
 575         struct lttng_ust_channel_buffer *lttng_chan = channel_get_private(chan);
 576
 577         *stream_id = lttng_chan->priv->id;
 578
 579         return 0;
 580 }
 581
 582 static int client_current_timestamp(struct lttng_ust_lib_ring_buffer *buf,
 583                 struct lttng_ust_lib_ring_buffer_channel *chan,
 584                 uint64_t *ts)
 585 {
 586         *ts = client_ring_buffer_clock_read(chan);
 587
 588         return 0;
 589 }
 590
 591 static int client_sequence_number(struct lttng_ust_lib_ring_buffer *buf,
 592                 struct lttng_ust_lib_ring_buffer_channel *chan,
 593                 uint64_t *seq)
 594 {
 595         struct lttng_ust_shm_handle *handle = chan->handle;
 596         struct packet_header *header;
 597
 598         header = client_packet_header(buf, handle);
 599         if (!header)
 600                 return -1;
 601         *seq = header->ctx.packet_seq_num;
 602         return 0;
 603 }
 604
 605 static int client_instance_id(struct lttng_ust_lib_ring_buffer *buf,
 606                 struct lttng_ust_lib_ring_buffer_channel *chan,
 607                 uint64_t *id)
 608 {
 609         *id = buf->backend.cpu;
 610
 611         return 0;
 612 }
 613
 614 static const
 615 struct lttng_ust_client_lib_ring_buffer_client_cb client_cb = {
 616         .parent = {
 617                 .ring_buffer_clock_read = client_ring_buffer_clock_read,
 618                 .record_header_size = client_record_header_size,
 619                 .subbuffer_header_size = client_packet_header_size,
 620                 .buffer_begin = client_buffer_begin,
 621                 .buffer_end = client_buffer_end,
 622                 .buffer_create = client_buffer_create,
 623                 .buffer_finalize = client_buffer_finalize,
 624                 .content_size_field = client_content_size_field,
 625                 .packet_size_field = client_packet_size_field,
 626         },
 627         .timestamp_begin = client_timestamp_begin,
 628         .timestamp_end = client_timestamp_end,
 629         .events_discarded = client_events_discarded,
 630         .content_size = client_content_size,
 631         .packet_size = client_packet_size,
 632         .stream_id = client_stream_id,
 633         .current_timestamp = client_current_timestamp,
 634         .sequence_number = client_sequence_number,
 635         .instance_id = client_instance_id,
 636 };
 637
 638 static const struct lttng_ust_lib_ring_buffer_config client_config = {
 639         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 640         .cb.record_header_size = client_record_header_size,
 641         .cb.subbuffer_header_size = client_packet_header_size,
 642         .cb.buffer_begin = client_buffer_begin,
 643         .cb.buffer_end = client_buffer_end,
 644         .cb.buffer_create = client_buffer_create,
 645         .cb.buffer_finalize = client_buffer_finalize,
 646         .cb.content_size_field = client_content_size_field,
 647         .cb.packet_size_field = client_packet_size_field,
 648
 649         .tsc_bits = LTTNG_COMPACT_TSC_BITS,
 650         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 651         .sync = RING_BUFFER_SYNC_GLOBAL,
 652         .mode = RING_BUFFER_MODE_TEMPLATE,
 653         .backend = RING_BUFFER_PAGE,
 654         .output = RING_BUFFER_MMAP,
 655         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 656         .ipi = RING_BUFFER_NO_IPI_BARRIER,
 657         .wakeup = LTTNG_CLIENT_WAKEUP,
 658         .client_type = LTTNG_CLIENT_TYPE,
 659
 660         .cb_ptr = &client_cb.parent,
 661 };
 662
 663 static
 664 struct lttng_ust_channel_buffer *_channel_create(const char *name,
 665                                 void *buf_addr,
 666                                 size_t subbuf_size, size_t num_subbuf,
 667                                 unsigned int switch_timer_interval,
 668                                 unsigned int read_timer_interval,
 669                                 unsigned char *uuid,
 670                                 uint32_t chan_id,
 671                                 const int *stream_fds, int nr_stream_fds,
 672                                 int64_t blocking_timeout)
 673 {
 674         struct lttng_ust_abi_channel_config chan_priv_init;
 675         struct lttng_ust_shm_handle *handle;
 676         struct lttng_ust_channel_buffer *lttng_chan_buf;
 677
 678         lttng_chan_buf = lttng_ust_alloc_channel_buffer();
 679         if (!lttng_chan_buf)
 680                 return NULL;
 681         memcpy(lttng_chan_buf->priv->uuid, uuid, LTTNG_UST_UUID_LEN);
 682         lttng_chan_buf->priv->id = chan_id;
 683
 684         memset(&chan_priv_init, 0, sizeof(chan_priv_init));
 685         memcpy(chan_priv_init.uuid, uuid, LTTNG_UST_UUID_LEN);
 686         chan_priv_init.id = chan_id;
 687
 688         handle = channel_create(&client_config, name,
 689                         __alignof__(struct lttng_ust_abi_channel_config),
 690                         sizeof(struct lttng_ust_abi_channel_config),
 691                         &chan_priv_init,
 692                         lttng_chan_buf, buf_addr, subbuf_size, num_subbuf,
 693                         switch_timer_interval, read_timer_interval,
 694                         stream_fds, nr_stream_fds, blocking_timeout);
 695         if (!handle)
 696                 goto error;
 697         lttng_chan_buf->priv->rb_chan = shmp(handle, handle->chan);
 698         return lttng_chan_buf;
 699
 700 error:
 701         lttng_ust_free_channel_common(lttng_chan_buf->parent);
 702         return NULL;
 703 }
 704
 705 static
 706 void lttng_channel_destroy(struct lttng_ust_channel_buffer *lttng_chan_buf)
 707 {
 708         channel_destroy(lttng_chan_buf->priv->rb_chan, lttng_chan_buf->priv->rb_chan->handle, 1);
 709         lttng_ust_free_channel_common(lttng_chan_buf->parent);
 710 }
 711
 712 static
 713 int lttng_event_reserve(struct lttng_ust_lib_ring_buffer_ctx *ctx)
 714 {
 715         struct lttng_ust_event_recorder *event_recorder = ctx->client_priv;
 716         struct lttng_ust_channel_buffer *lttng_chan = event_recorder->chan;
 717         struct lttng_client_ctx client_ctx;
 718         int ret, nesting;
 719         struct lttng_ust_lib_ring_buffer_ctx_private *private_ctx;
 720         uint32_t event_id;
 721
 722         event_id = event_recorder->priv->id;
 723         client_ctx.chan_ctx = lttng_ust_rcu_dereference(lttng_chan->priv->ctx);
 724         client_ctx.event_ctx = lttng_ust_rcu_dereference(event_recorder->priv->ctx);
 725         /* Compute internal size of context structures. */
 726         ctx_get_struct_size(client_ctx.chan_ctx, &client_ctx.packet_context_len,
 727                         APP_CTX_ENABLED);
 728         ctx_get_struct_size(client_ctx.event_ctx, &client_ctx.event_context_len,
 729                         APP_CTX_ENABLED);
 730
 731         nesting = lib_ring_buffer_nesting_inc(&client_config);
 732         if (nesting < 0)
 733                 return -EPERM;
 734
 735         private_ctx = &URCU_TLS(private_ctx_stack[nesting]);
 736         memset(private_ctx, 0, sizeof(*private_ctx));
 737         private_ctx->pub = ctx;
 738         private_ctx->chan = lttng_chan->priv->rb_chan;
 739
 740         ctx->priv = private_ctx;
 741
 742         switch (lttng_chan->priv->header_type) {
 743         case 1: /* compact */
 744                 if (event_id > 30)
 745                         private_ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 746                 break;
 747         case 2: /* large */
 748                 if (event_id > 65534)
 749                         private_ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 750                 break;
 751         default:
 752                 WARN_ON_ONCE(1);
 753         }
 754
 755         ret = lib_ring_buffer_reserve(&client_config, ctx, &client_ctx);
 756         if (caa_unlikely(ret))
 757                 goto put;
 758         if (lib_ring_buffer_backend_get_pages(&client_config, ctx,
 759                         &private_ctx->backend_pages)) {
 760                 ret = -EPERM;
 761                 goto put;
 762         }
 763         lttng_write_event_header(&client_config, ctx, &client_ctx, event_id);
 764         return 0;
 765 put:
 766         lib_ring_buffer_nesting_dec(&client_config);
 767         return ret;
 768 }
 769
 770 static
 771 void lttng_event_commit(struct lttng_ust_lib_ring_buffer_ctx *ctx)
 772 {
 773         lib_ring_buffer_commit(&client_config, ctx);
 774         lib_ring_buffer_nesting_dec(&client_config);
 775 }
 776
 777 static
 778 void lttng_event_write(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 779                 const void *src, size_t len, size_t alignment)
 780 {
 781         lttng_ust_lib_ring_buffer_align_ctx(ctx, alignment);
 782         lib_ring_buffer_write(&client_config, ctx, src, len);
 783 }
 784
 785 static
 786 void lttng_event_strcpy(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 787                 const char *src, size_t len)
 788 {
 789         lib_ring_buffer_strcpy(&client_config, ctx, src, len, '#');
 790 }
 791
 792 static
 793 void lttng_event_pstrcpy_pad(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 794                 const char *src, size_t len)
 795 {
 796         lib_ring_buffer_pstrcpy(&client_config, ctx, src, len, '\0');
 797 }
 798
 799 static
 800 int lttng_is_finalized(struct lttng_ust_channel_buffer *chan)
 801 {
 802         struct lttng_ust_lib_ring_buffer_channel *rb_chan = chan->priv->rb_chan;
 803
 804         return lib_ring_buffer_channel_is_finalized(rb_chan);
 805 }
 806
 807 static
 808 int lttng_is_disabled(struct lttng_ust_channel_buffer *chan)
 809 {
 810         struct lttng_ust_lib_ring_buffer_channel *rb_chan = chan->priv->rb_chan;
 811
 812         return lib_ring_buffer_channel_is_disabled(rb_chan);
 813 }
 814
 815 static
 816 int lttng_flush_buffer(struct lttng_ust_channel_buffer *chan)
 817 {
 818         struct lttng_ust_lib_ring_buffer_channel *rb_chan = chan->priv->rb_chan;
 819         struct lttng_ust_lib_ring_buffer *buf;
 820         int cpu;
 821
 822         for_each_channel_cpu(cpu, rb_chan) {
 823                 int shm_fd, wait_fd, wakeup_fd;
 824                 uint64_t memory_map_size;
 825
 826                 buf = channel_get_ring_buffer(&client_config, rb_chan,
 827                                 cpu, rb_chan->handle, &shm_fd, &wait_fd,
 828                                 &wakeup_fd, &memory_map_size);
 829                 lib_ring_buffer_switch(&client_config, buf,
 830                                 SWITCH_ACTIVE, rb_chan->handle);
 831         }
 832         return 0;
 833 }
 834
 835 static struct lttng_transport lttng_relay_transport = {
 836         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap",
 837         .ops = {
 838                 .struct_size = sizeof(struct lttng_ust_channel_buffer_ops),
 839                 .priv = __LTTNG_COMPOUND_LITERAL(struct lttng_ust_channel_buffer_ops_private, {
 840                         .pub = &lttng_relay_transport.ops,
 841                         .channel_create = _channel_create,
 842                         .channel_destroy = lttng_channel_destroy,
 843                         .packet_avail_size = NULL,      /* Would be racy anyway */
 844                         .is_finalized = lttng_is_finalized,
 845                         .is_disabled = lttng_is_disabled,
 846                         .flush_buffer = lttng_flush_buffer,
 847                 }),
 848                 .event_reserve = lttng_event_reserve,
 849                 .event_commit = lttng_event_commit,
 850                 .event_write = lttng_event_write,
 851                 .event_strcpy = lttng_event_strcpy,
 852                 .event_pstrcpy_pad = lttng_event_pstrcpy_pad,
 853         },
 854         .client_config = &client_config,
 855 };
 856
 857 void RING_BUFFER_MODE_TEMPLATE_INIT(void)
 858 {
 859         DBG("LTT : ltt ring buffer client \"%s\" init\n",
 860                 "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap");
 861         lttng_fixup_rb_client_tls();
 862         lttng_transport_register(&lttng_relay_transport);
 863 }
 864
 865 void RING_BUFFER_MODE_TEMPLATE_EXIT(void)
 866 {
 867         DBG("LTT : ltt ring buffer client \"%s\" exit\n",
 868                 "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap");
 869         lttng_transport_unregister(&lttng_relay_transport);
 870 }