liblttng-ust/lttng-ring-buffer-client.h

   1 /*
   2  * lttng-ring-buffer-client.h
   3  *
   4  * LTTng lib ring buffer client template.
   5  *
   6  * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include <stdint.h>
  24 #include <lttng/ust-events.h>
  25 #include "lttng/bitfield.h"
  26 #include "clock.h"
  27 #include "lttng-tracer.h"
  28 #include "../libringbuffer/frontend_types.h"
  29 #include "../libringbuffer/rseq.h"
  30
  31 #define LTTNG_COMPACT_EVENT_BITS       5
  32 #define LTTNG_COMPACT_TSC_BITS         27
  33 #define LTTNG_RSEQ_ATTEMPTS             8
  34
  35 enum app_ctx_mode {
  36         APP_CTX_DISABLED,
  37         APP_CTX_ENABLED,
  38 };
  39
  40 /*
  41  * Keep the natural field alignment for _each field_ within this structure if
  42  * you ever add/remove a field from this header. Packed attribute is not used
  43  * because gcc generates poor code on at least powerpc and mips. Don't ever
  44  * let gcc add padding between the structure elements.
  45  */
  46
  47 struct packet_header {
  48         /* Trace packet header */
  49         uint32_t magic;                 /*
  50                                          * Trace magic number.
  51                                          * contains endianness information.
  52                                          */
  53         uint8_t uuid[LTTNG_UST_UUID_LEN];
  54         uint32_t stream_id;
  55         uint64_t stream_instance_id;
  56
  57         struct {
  58                 /* Stream packet context */
  59                 uint64_t timestamp_begin;       /* Cycle count at subbuffer start */
  60                 uint64_t timestamp_end;         /* Cycle count at subbuffer end */
  61                 uint64_t content_size;          /* Size of data in subbuffer */
  62                 uint64_t packet_size;           /* Subbuffer size (include padding) */
  63                 uint64_t packet_seq_num;        /* Packet sequence number */
  64                 unsigned long events_discarded; /*
  65                                                  * Events lost in this subbuffer since
  66                                                  * the beginning of the trace.
  67                                                  * (may overflow)
  68                                                  */
  69                 uint32_t cpu_id;                /* CPU id associated with stream */
  70                 uint8_t header_end;             /* End of header */
  71         } ctx;
  72 };
  73
  74
  75 static inline uint64_t lib_ring_buffer_clock_read(struct channel *chan)
  76 {
  77         return trace_clock_read64();
  78 }
  79
  80 static inline
  81 size_t ctx_get_size(size_t offset, struct lttng_ctx *ctx,
  82                 enum app_ctx_mode mode)
  83 {
  84         int i;
  85         size_t orig_offset = offset;
  86
  87         if (caa_likely(!ctx))
  88                 return 0;
  89         offset += lib_ring_buffer_align(offset, ctx->largest_align);
  90         for (i = 0; i < ctx->nr_fields; i++) {
  91                 if (mode == APP_CTX_ENABLED) {
  92                         offset += ctx->fields[i].get_size(&ctx->fields[i], offset);
  93                 } else {
  94                         if (lttng_context_is_app(ctx->fields[i].event_field.name)) {
  95                                 /*
  96                                  * Before UST 2.8, we cannot use the
  97                                  * application context, because we
  98                                  * cannot trust that the handler used
  99                                  * for get_size is the same used for
 100                                  * ctx_record, which would result in
 101                                  * corrupted traces when tracing
 102                                  * concurrently with application context
 103                                  * register/unregister.
 104                                  */
 105                                 offset += lttng_ust_dummy_get_size(&ctx->fields[i], offset);
 106                         } else {
 107                                 offset += ctx->fields[i].get_size(&ctx->fields[i], offset);
 108                         }
 109                 }
 110         }
 111         return offset - orig_offset;
 112 }
 113
 114 static inline
 115 void ctx_record(struct lttng_ust_lib_ring_buffer_ctx *bufctx,
 116                 struct lttng_channel *chan,
 117                 struct lttng_ctx *ctx,
 118                 enum app_ctx_mode mode)
 119 {
 120         int i;
 121
 122         if (caa_likely(!ctx))
 123                 return;
 124         lib_ring_buffer_align_ctx(bufctx, ctx->largest_align);
 125         for (i = 0; i < ctx->nr_fields; i++) {
 126                 if (mode == APP_CTX_ENABLED) {
 127                         ctx->fields[i].record(&ctx->fields[i], bufctx, chan);
 128                 } else {
 129                         if (lttng_context_is_app(ctx->fields[i].event_field.name)) {
 130                                 /*
 131                                  * Before UST 2.8, we cannot use the
 132                                  * application context, because we
 133                                  * cannot trust that the handler used
 134                                  * for get_size is the same used for
 135                                  * ctx_record, which would result in
 136                                  * corrupted traces when tracing
 137                                  * concurrently with application context
 138                                  * register/unregister.
 139                                  */
 140                                 lttng_ust_dummy_record(&ctx->fields[i], bufctx, chan);
 141                         } else {
 142                                 ctx->fields[i].record(&ctx->fields[i], bufctx, chan);
 143                         }
 144                 }
 145         }
 146 }
 147
 148 /*
 149  * record_header_size - Calculate the header size and padding necessary.
 150  * @config: ring buffer instance configuration
 151  * @chan: channel
 152  * @offset: offset in the write buffer
 153  * @pre_header_padding: padding to add before the header (output)
 154  * @ctx: reservation context
 155  *
 156  * Returns the event header size (including padding).
 157  *
 158  * The payload must itself determine its own alignment from the biggest type it
 159  * contains.
 160  */
 161 static __inline__
 162 size_t record_header_size(const struct lttng_ust_lib_ring_buffer_config *config,
 163                                  struct channel *chan, size_t offset,
 164                                  size_t *pre_header_padding,
 165                                  struct lttng_ust_lib_ring_buffer_ctx *ctx)
 166 {
 167         struct lttng_channel *lttng_chan = channel_get_private(chan);
 168         struct lttng_event *event = ctx->priv;
 169         struct lttng_stack_ctx *lttng_ctx = ctx->priv2;
 170         size_t orig_offset = offset;
 171         size_t padding;
 172
 173         switch (lttng_chan->header_type) {
 174         case 1: /* compact */
 175                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 176                 offset += padding;
 177                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 178                         offset += sizeof(uint32_t);     /* id and timestamp */
 179                 } else {
 180                         /* Minimum space taken by LTTNG_COMPACT_EVENT_BITS id */
 181                         offset += (LTTNG_COMPACT_EVENT_BITS + CHAR_BIT - 1) / CHAR_BIT;
 182                         /* Align extended struct on largest member */
 183                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 184                         offset += sizeof(uint32_t);     /* id */
 185                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 186                         offset += sizeof(uint64_t);     /* timestamp */
 187                 }
 188                 break;
 189         case 2: /* large */
 190                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint16_t));
 191                 offset += padding;
 192                 offset += sizeof(uint16_t);
 193                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 194                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 195                         offset += sizeof(uint32_t);     /* timestamp */
 196                 } else {
 197                         /* Align extended struct on largest member */
 198                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 199                         offset += sizeof(uint32_t);     /* id */
 200                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 201                         offset += sizeof(uint64_t);     /* timestamp */
 202                 }
 203                 break;
 204         default:
 205                 padding = 0;
 206                 WARN_ON_ONCE(1);
 207         }
 208         if (lttng_ctx) {
 209                 /* 2.8+ probe ABI. */
 210                 offset += ctx_get_size(offset, lttng_ctx->chan_ctx, APP_CTX_ENABLED);
 211                 offset += ctx_get_size(offset, lttng_ctx->event_ctx, APP_CTX_ENABLED);
 212         } else {
 213                 /* Pre 2.8 probe ABI. */
 214                 offset += ctx_get_size(offset, lttng_chan->ctx, APP_CTX_DISABLED);
 215                 offset += ctx_get_size(offset, event->ctx, APP_CTX_DISABLED);
 216         }
 217         *pre_header_padding = padding;
 218         return offset - orig_offset;
 219 }
 220
 221 #include "../libringbuffer/api.h"
 222 #include "lttng-rb-clients.h"
 223
 224 static
 225 void lttng_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config *config,
 226                                  struct lttng_ust_lib_ring_buffer_ctx *ctx,
 227                                  uint32_t event_id);
 228
 229 /*
 230  * lttng_write_event_header
 231  *
 232  * Writes the event header to the offset (already aligned on 32-bits).
 233  *
 234  * @config: ring buffer instance configuration
 235  * @ctx: reservation context
 236  * @event_id: event ID
 237  */
 238 static __inline__
 239 void lttng_write_event_header(const struct lttng_ust_lib_ring_buffer_config *config,
 240                             struct lttng_ust_lib_ring_buffer_ctx *ctx,
 241                             uint32_t event_id)
 242 {
 243         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 244         struct lttng_event *event = ctx->priv;
 245         struct lttng_stack_ctx *lttng_ctx = ctx->priv2;
 246
 247         if (caa_unlikely(ctx->rflags))
 248                 goto slow_path;
 249
 250         switch (lttng_chan->header_type) {
 251         case 1: /* compact */
 252         {
 253                 uint32_t id_time = 0;
 254
 255                 bt_bitfield_write(&id_time, uint32_t,
 256                                 0,
 257                                 LTTNG_COMPACT_EVENT_BITS,
 258                                 event_id);
 259                 bt_bitfield_write(&id_time, uint32_t,
 260                                 LTTNG_COMPACT_EVENT_BITS,
 261                                 LTTNG_COMPACT_TSC_BITS,
 262                                 ctx->tsc);
 263                 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 264                 break;
 265         }
 266         case 2: /* large */
 267         {
 268                 uint32_t timestamp = (uint32_t) ctx->tsc;
 269                 uint16_t id = event_id;
 270
 271                 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 272                 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 273                 lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 274                 break;
 275         }
 276         default:
 277                 WARN_ON_ONCE(1);
 278         }
 279
 280         if (lttng_ctx) {
 281                 /* 2.8+ probe ABI. */
 282                 ctx_record(ctx, lttng_chan, lttng_ctx->chan_ctx, APP_CTX_ENABLED);
 283                 ctx_record(ctx, lttng_chan, lttng_ctx->event_ctx, APP_CTX_ENABLED);
 284         } else {
 285                 /* Pre 2.8 probe ABI. */
 286                 ctx_record(ctx, lttng_chan, lttng_chan->ctx, APP_CTX_DISABLED);
 287                 ctx_record(ctx, lttng_chan, event->ctx, APP_CTX_DISABLED);
 288         }
 289         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 290
 291         return;
 292
 293 slow_path:
 294         lttng_write_event_header_slow(config, ctx, event_id);
 295 }
 296
 297 static
 298 void lttng_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config *config,
 299                                  struct lttng_ust_lib_ring_buffer_ctx *ctx,
 300                                  uint32_t event_id)
 301 {
 302         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 303         struct lttng_event *event = ctx->priv;
 304         struct lttng_stack_ctx *lttng_ctx = ctx->priv2;
 305
 306         switch (lttng_chan->header_type) {
 307         case 1: /* compact */
 308                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 309                         uint32_t id_time = 0;
 310
 311                         bt_bitfield_write(&id_time, uint32_t,
 312                                         0,
 313                                         LTTNG_COMPACT_EVENT_BITS,
 314                                         event_id);
 315                         bt_bitfield_write(&id_time, uint32_t,
 316                                         LTTNG_COMPACT_EVENT_BITS,
 317                                         LTTNG_COMPACT_TSC_BITS,
 318                                         ctx->tsc);
 319                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 320                 } else {
 321                         uint8_t id = 0;
 322                         uint64_t timestamp = ctx->tsc;
 323
 324                         bt_bitfield_write(&id, uint8_t,
 325                                         0,
 326                                         LTTNG_COMPACT_EVENT_BITS,
 327                                         31);
 328                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 329                         /* Align extended struct on largest member */
 330                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 331                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 332                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 333                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 334                 }
 335                 break;
 336         case 2: /* large */
 337         {
 338                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 339                         uint32_t timestamp = (uint32_t) ctx->tsc;
 340                         uint16_t id = event_id;
 341
 342                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 343                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 344                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 345                 } else {
 346                         uint16_t id = 65535;
 347                         uint64_t timestamp = ctx->tsc;
 348
 349                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 350                         /* Align extended struct on largest member */
 351                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 352                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 353                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 354                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 355                 }
 356                 break;
 357         }
 358         default:
 359                 WARN_ON_ONCE(1);
 360         }
 361         if (lttng_ctx) {
 362                 /* 2.8+ probe ABI. */
 363                 ctx_record(ctx, lttng_chan, lttng_ctx->chan_ctx, APP_CTX_ENABLED);
 364                 ctx_record(ctx, lttng_chan, lttng_ctx->event_ctx, APP_CTX_ENABLED);
 365         } else {
 366                 /* Pre 2.8 probe ABI. */
 367                 ctx_record(ctx, lttng_chan, lttng_chan->ctx, APP_CTX_DISABLED);
 368                 ctx_record(ctx, lttng_chan, event->ctx, APP_CTX_DISABLED);
 369         }
 370         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 371 }
 372
 373 static const struct lttng_ust_lib_ring_buffer_config client_config;
 374
 375 static uint64_t client_ring_buffer_clock_read(struct channel *chan)
 376 {
 377         return lib_ring_buffer_clock_read(chan);
 378 }
 379
 380 static
 381 size_t client_record_header_size(const struct lttng_ust_lib_ring_buffer_config *config,
 382                                  struct channel *chan, size_t offset,
 383                                  size_t *pre_header_padding,
 384                                  struct lttng_ust_lib_ring_buffer_ctx *ctx)
 385 {
 386         return record_header_size(config, chan, offset,
 387                                   pre_header_padding, ctx);
 388 }
 389
 390 /**
 391  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 392  *
 393  * Return header size without padding after the structure. Don't use packed
 394  * structure because gcc generates inefficient code on some architectures
 395  * (powerpc, mips..)
 396  */
 397 static size_t client_packet_header_size(void)
 398 {
 399         return offsetof(struct packet_header, ctx.header_end);
 400 }
 401
 402 static void client_buffer_begin(struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
 403                                 unsigned int subbuf_idx,
 404                                 struct lttng_ust_shm_handle *handle)
 405 {
 406         struct channel *chan = shmp(handle, buf->backend.chan);
 407         struct packet_header *header =
 408                 (struct packet_header *)
 409                         lib_ring_buffer_offset_address(&buf->backend,
 410                                 subbuf_idx * chan->backend.subbuf_size,
 411                                 handle);
 412         struct lttng_channel *lttng_chan = channel_get_private(chan);
 413         uint64_t cnt = shmp_index(handle, buf->backend.buf_cnt, subbuf_idx)->seq_cnt;
 414
 415         assert(header);
 416         if (!header)
 417                 return;
 418         header->magic = CTF_MAGIC_NUMBER;
 419         memcpy(header->uuid, lttng_chan->uuid, sizeof(lttng_chan->uuid));
 420         header->stream_id = lttng_chan->id;
 421         header->stream_instance_id = buf->backend.cpu;
 422         header->ctx.timestamp_begin = tsc;
 423         header->ctx.timestamp_end = 0;
 424         header->ctx.content_size = ~0ULL; /* for debugging */
 425         header->ctx.packet_size = ~0ULL;
 426         header->ctx.packet_seq_num = chan->backend.num_subbuf * cnt + subbuf_idx;
 427         header->ctx.events_discarded = 0;
 428         header->ctx.cpu_id = buf->backend.cpu;
 429 }
 430
 431 /*
 432  * offset is assumed to never be 0 here : never deliver a completely empty
 433  * subbuffer. data_size is between 1 and subbuf_size.
 434  */
 435 static void client_buffer_end(struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
 436                               unsigned int subbuf_idx, unsigned long data_size,
 437                               struct lttng_ust_shm_handle *handle)
 438 {
 439         struct channel *chan = shmp(handle, buf->backend.chan);
 440         struct packet_header *header =
 441                 (struct packet_header *)
 442                         lib_ring_buffer_offset_address(&buf->backend,
 443                                 subbuf_idx * chan->backend.subbuf_size,
 444                                 handle);
 445         unsigned long records_lost = 0;
 446
 447         assert(header);
 448         if (!header)
 449                 return;
 450         header->ctx.timestamp_end = tsc;
 451         header->ctx.content_size =
 452                 (uint64_t) data_size * CHAR_BIT;                /* in bits */
 453         header->ctx.packet_size =
 454                 (uint64_t) PAGE_ALIGN(data_size) * CHAR_BIT;    /* in bits */
 455
 456         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
 457         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 458         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 459         header->ctx.events_discarded = records_lost;
 460 }
 461
 462 static int client_buffer_create(struct lttng_ust_lib_ring_buffer *buf, void *priv,
 463                                 int cpu, const char *name, struct lttng_ust_shm_handle *handle)
 464 {
 465         return 0;
 466 }
 467
 468 static void client_buffer_finalize(struct lttng_ust_lib_ring_buffer *buf, void *priv, int cpu, struct lttng_ust_shm_handle *handle)
 469 {
 470 }
 471
 472 static void client_content_size_field(const struct lttng_ust_lib_ring_buffer_config *config,
 473                                       size_t *offset, size_t *length)
 474 {
 475         *offset = offsetof(struct packet_header, ctx.content_size);
 476         *length = sizeof(((struct packet_header *) NULL)->ctx.content_size);
 477 }
 478
 479 static void client_packet_size_field(const struct lttng_ust_lib_ring_buffer_config *config,
 480                                       size_t *offset, size_t *length)
 481 {
 482         *offset = offsetof(struct packet_header, ctx.packet_size);
 483         *length = sizeof(((struct packet_header *) NULL)->ctx.packet_size);
 484 }
 485
 486 static struct packet_header *client_packet_header(struct lttng_ust_lib_ring_buffer *buf,
 487                 struct lttng_ust_shm_handle *handle)
 488 {
 489         return lib_ring_buffer_read_offset_address(&buf->backend, 0, handle);
 490 }
 491
 492 static int client_timestamp_begin(struct lttng_ust_lib_ring_buffer *buf,
 493                 struct lttng_ust_shm_handle *handle,
 494                 uint64_t *timestamp_begin)
 495 {
 496         struct packet_header *header;
 497
 498         header = client_packet_header(buf, handle);
 499         if (!header)
 500                 return -1;
 501         *timestamp_begin = header->ctx.timestamp_begin;
 502         return 0;
 503 }
 504
 505 static int client_timestamp_end(struct lttng_ust_lib_ring_buffer *buf,
 506                 struct lttng_ust_shm_handle *handle,
 507                 uint64_t *timestamp_end)
 508 {
 509         struct packet_header *header;
 510
 511         header = client_packet_header(buf, handle);
 512         if (!header)
 513                 return -1;
 514         *timestamp_end = header->ctx.timestamp_end;
 515         return 0;
 516 }
 517
 518 static int client_events_discarded(struct lttng_ust_lib_ring_buffer *buf,
 519                 struct lttng_ust_shm_handle *handle,
 520                 uint64_t *events_discarded)
 521 {
 522         struct packet_header *header;
 523
 524         header = client_packet_header(buf, handle);
 525         if (!header)
 526                 return -1;
 527         *events_discarded = header->ctx.events_discarded;
 528         return 0;
 529 }
 530
 531 static int client_content_size(struct lttng_ust_lib_ring_buffer *buf,
 532                 struct lttng_ust_shm_handle *handle,
 533                 uint64_t *content_size)
 534 {
 535         struct packet_header *header;
 536
 537         header = client_packet_header(buf, handle);
 538         if (!header)
 539                 return -1;
 540         *content_size = header->ctx.content_size;
 541         return 0;
 542 }
 543
 544 static int client_packet_size(struct lttng_ust_lib_ring_buffer *buf,
 545                 struct lttng_ust_shm_handle *handle,
 546                 uint64_t *packet_size)
 547 {
 548         struct packet_header *header;
 549
 550         header = client_packet_header(buf, handle);
 551         if (!header)
 552                 return -1;
 553         *packet_size = header->ctx.packet_size;
 554         return 0;
 555 }
 556
 557 static int client_stream_id(struct lttng_ust_lib_ring_buffer *buf,
 558                 struct lttng_ust_shm_handle *handle,
 559                 uint64_t *stream_id)
 560 {
 561         struct packet_header *header;
 562
 563         header = client_packet_header(buf, handle);
 564         if (!header)
 565                 return -1;
 566         *stream_id = header->stream_id;
 567         return 0;
 568 }
 569
 570 static int client_current_timestamp(struct lttng_ust_lib_ring_buffer *buf,
 571                 struct lttng_ust_shm_handle *handle,
 572                 uint64_t *ts)
 573 {
 574         struct channel *chan;
 575
 576         chan = shmp(handle, handle->chan);
 577         *ts = client_ring_buffer_clock_read(chan);
 578
 579         return 0;
 580 }
 581
 582 static int client_sequence_number(struct lttng_ust_lib_ring_buffer *buf,
 583                 struct lttng_ust_shm_handle *handle,
 584                 uint64_t *seq)
 585 {
 586         struct packet_header *header;
 587
 588         header = client_packet_header(buf, handle);
 589         *seq = header->ctx.packet_seq_num;
 590         return 0;
 591 }
 592
 593 static int client_instance_id(struct lttng_ust_lib_ring_buffer *buf,
 594                 struct lttng_ust_shm_handle *handle,
 595                 uint64_t *id)
 596 {
 597         struct packet_header *header;
 598
 599         header = client_packet_header(buf, handle);
 600         *id = header->stream_instance_id;
 601         return 0;
 602 }
 603
 604 static const
 605 struct lttng_ust_client_lib_ring_buffer_client_cb client_cb = {
 606         .parent = {
 607                 .ring_buffer_clock_read = client_ring_buffer_clock_read,
 608                 .record_header_size = client_record_header_size,
 609                 .subbuffer_header_size = client_packet_header_size,
 610                 .buffer_begin = client_buffer_begin,
 611                 .buffer_end = client_buffer_end,
 612                 .buffer_create = client_buffer_create,
 613                 .buffer_finalize = client_buffer_finalize,
 614                 .content_size_field = client_content_size_field,
 615                 .packet_size_field = client_packet_size_field,
 616         },
 617         .timestamp_begin = client_timestamp_begin,
 618         .timestamp_end = client_timestamp_end,
 619         .events_discarded = client_events_discarded,
 620         .content_size = client_content_size,
 621         .packet_size = client_packet_size,
 622         .stream_id = client_stream_id,
 623         .current_timestamp = client_current_timestamp,
 624         .sequence_number = client_sequence_number,
 625         .instance_id = client_instance_id,
 626 };
 627
 628 static const struct lttng_ust_lib_ring_buffer_config client_config = {
 629         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 630         .cb.record_header_size = client_record_header_size,
 631         .cb.subbuffer_header_size = client_packet_header_size,
 632         .cb.buffer_begin = client_buffer_begin,
 633         .cb.buffer_end = client_buffer_end,
 634         .cb.buffer_create = client_buffer_create,
 635         .cb.buffer_finalize = client_buffer_finalize,
 636         .cb.content_size_field = client_content_size_field,
 637         .cb.packet_size_field = client_packet_size_field,
 638
 639         .tsc_bits = LTTNG_COMPACT_TSC_BITS,
 640         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 641         .sync = RING_BUFFER_SYNC_PER_CPU,
 642         .mode = RING_BUFFER_MODE_TEMPLATE,
 643         .backend = RING_BUFFER_PAGE,
 644         .output = RING_BUFFER_MMAP,
 645         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 646         .ipi = RING_BUFFER_NO_IPI_BARRIER,
 647         .wakeup = LTTNG_CLIENT_WAKEUP,
 648         .client_type = LTTNG_CLIENT_TYPE,
 649
 650         .cb_ptr = &client_cb.parent,
 651 };
 652
 653 const struct lttng_ust_client_lib_ring_buffer_client_cb *LTTNG_CLIENT_CALLBACKS = &client_cb;
 654
 655 static
 656 struct lttng_channel *_channel_create(const char *name,
 657                                 void *buf_addr,
 658                                 size_t subbuf_size, size_t num_subbuf,
 659                                 unsigned int switch_timer_interval,
 660                                 unsigned int read_timer_interval,
 661                                 unsigned char *uuid,
 662                                 uint32_t chan_id,
 663                                 const int *stream_fds, int nr_stream_fds)
 664 {
 665         struct lttng_channel chan_priv_init;
 666         struct lttng_ust_shm_handle *handle;
 667         struct lttng_channel *lttng_chan;
 668         void *priv;
 669
 670         memset(&chan_priv_init, 0, sizeof(chan_priv_init));
 671         memcpy(chan_priv_init.uuid, uuid, LTTNG_UST_UUID_LEN);
 672         chan_priv_init.id = chan_id;
 673         handle = channel_create(&client_config, name,
 674                         &priv, __alignof__(struct lttng_channel),
 675                         sizeof(struct lttng_channel),
 676                         &chan_priv_init,
 677                         buf_addr, subbuf_size, num_subbuf,
 678                         switch_timer_interval, read_timer_interval,
 679                         stream_fds, nr_stream_fds);
 680         if (!handle)
 681                 return NULL;
 682         lttng_chan = priv;
 683         lttng_chan->handle = handle;
 684         lttng_chan->chan = shmp(handle, handle->chan);
 685         return lttng_chan;
 686 }
 687
 688 static
 689 void lttng_channel_destroy(struct lttng_channel *chan)
 690 {
 691         channel_destroy(chan->chan, chan->handle, 1);
 692 }
 693
 694 static
 695 bool refcount_get_saturate(long *ref)
 696 {
 697         long old, _new, res;
 698
 699         old = uatomic_read(ref);
 700         for (;;) {
 701                 if (old == LONG_MAX) {
 702                         return false;   /* Saturated. */
 703                 }
 704                 _new = old + 1;
 705                 res = uatomic_cmpxchg(ref, old, _new);
 706                 if (res == old) {
 707                         if (_new == LONG_MAX) {
 708                                 return false; /* Saturation. */
 709                         }
 710                         return true;    /* Success. */
 711                 }
 712                 old = res;
 713         }
 714 }
 715
 716 static
 717 int lttng_event_reserve(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 718                       uint32_t event_id)
 719 {
 720         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 721         struct lttng_rseq_state rseq_state;
 722         int ret, cpu, attempt = 0;
 723         bool put_fallback_ref = false;
 724
 725         if (lib_ring_buffer_begin(&client_config))
 726                 return -EPERM;
 727 retry:
 728         rseq_state = rseq_start();
 729         if (caa_unlikely(rseq_cpu_at_start(rseq_state) < 0)) {
 730                 if (caa_unlikely(rseq_cpu_at_start(rseq_state) == -1)) {
 731                         if (!rseq_register_current_thread())
 732                                 goto retry;
 733                 }
 734                 /* rseq is unavailable. */
 735                 cpu = lib_ring_buffer_get_cpu(&client_config);
 736                 if (caa_unlikely(cpu < 0)) {
 737                         ret = -EPERM;
 738                         goto end;
 739                 }
 740         } else {
 741                 cpu = rseq_cpu_at_start(rseq_state);
 742         }
 743 fallback:
 744         ctx->cpu = cpu;
 745
 746         switch (lttng_chan->header_type) {
 747         case 1: /* compact */
 748                 if (event_id > 30)
 749                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 750                 break;
 751         case 2: /* large */
 752                 if (event_id > 65534)
 753                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 754                 break;
 755         default:
 756                 WARN_ON_ONCE(1);
 757         }
 758
 759         if (caa_likely(ctx->ctx_len
 760                         >= sizeof(struct lttng_ust_lib_ring_buffer_ctx)))
 761                 ctx->rseq_state = rseq_state;
 762
 763         ret = lib_ring_buffer_reserve(&client_config, ctx);
 764         if (caa_unlikely(ret)) {
 765                 if (ret == -EAGAIN) {
 766                         assert(!put_fallback_ref);
 767                         if (++attempt < LTTNG_RSEQ_ATTEMPTS) {
 768                                 caa_cpu_relax();
 769                                 goto retry;
 770                         }
 771                         put_fallback_ref = refcount_get_saturate(
 772                                 &lttng_chan->chan->u.reserve_fallback_ref);
 773                         cpu = lib_ring_buffer_get_cpu(&client_config);
 774                         if (caa_unlikely(cpu < 0)) {
 775                                 ret = -EPERM;
 776                                 goto end;
 777                         }
 778                         goto fallback;
 779                 }
 780                 goto end;
 781         }
 782         if (caa_likely(ctx->ctx_len
 783                         >= sizeof(struct lttng_ust_lib_ring_buffer_ctx))) {
 784                 if (lib_ring_buffer_backend_get_pages(&client_config, ctx,
 785                                 &ctx->backend_pages)) {
 786                         ret = -EPERM;
 787                         goto end;
 788                 }
 789         }
 790         lttng_write_event_header(&client_config, ctx, event_id);
 791
 792         if (caa_unlikely(put_fallback_ref))
 793                 uatomic_dec(&lttng_chan->chan->u.reserve_fallback_ref);
 794
 795         return 0;
 796 end:
 797         lib_ring_buffer_end(&client_config);
 798         if (put_fallback_ref)
 799                 uatomic_dec(&lttng_chan->chan->u.reserve_fallback_ref);
 800         return ret;
 801 }
 802
 803 static
 804 void lttng_event_commit(struct lttng_ust_lib_ring_buffer_ctx *ctx)
 805 {
 806         lib_ring_buffer_commit(&client_config, ctx);
 807         lib_ring_buffer_end(&client_config);
 808 }
 809
 810 static
 811 void lttng_event_write(struct lttng_ust_lib_ring_buffer_ctx *ctx, const void *src,
 812                      size_t len)
 813 {
 814         lib_ring_buffer_write(&client_config, ctx, src, len);
 815 }
 816
 817 static
 818 void lttng_event_strcpy(struct lttng_ust_lib_ring_buffer_ctx *ctx, const char *src,
 819                      size_t len)
 820 {
 821         lib_ring_buffer_strcpy(&client_config, ctx, src, len, '#');
 822 }
 823
 824 #if 0
 825 static
 826 wait_queue_head_t *lttng_get_reader_wait_queue(struct channel *chan)
 827 {
 828         return &chan->read_wait;
 829 }
 830
 831 static
 832 wait_queue_head_t *lttng_get_hp_wait_queue(struct channel *chan)
 833 {
 834         return &chan->hp_wait;
 835 }
 836 #endif //0
 837
 838 static
 839 int lttng_is_finalized(struct channel *chan)
 840 {
 841         return lib_ring_buffer_channel_is_finalized(chan);
 842 }
 843
 844 static
 845 int lttng_is_disabled(struct channel *chan)
 846 {
 847         return lib_ring_buffer_channel_is_disabled(chan);
 848 }
 849
 850 static
 851 int lttng_flush_buffer(struct channel *chan, struct lttng_ust_shm_handle *handle)
 852 {
 853         struct lttng_ust_lib_ring_buffer *buf;
 854         int cpu;
 855
 856         for_each_channel_cpu(cpu, chan) {
 857                 int shm_fd, wait_fd, wakeup_fd;
 858                 uint64_t memory_map_size;
 859
 860                 buf = channel_get_ring_buffer(&client_config, chan,
 861                                 cpu, handle, &shm_fd, &wait_fd,
 862                                 &wakeup_fd, &memory_map_size);
 863                 lib_ring_buffer_switch(&client_config, buf,
 864                                 SWITCH_ACTIVE, handle);
 865         }
 866         return 0;
 867 }
 868
 869 static struct lttng_transport lttng_relay_transport = {
 870         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap",
 871         .ops = {
 872                 .channel_create = _channel_create,
 873                 .channel_destroy = lttng_channel_destroy,
 874                 .u.has_strcpy = 1,
 875                 .event_reserve = lttng_event_reserve,
 876                 .event_commit = lttng_event_commit,
 877                 .event_write = lttng_event_write,
 878                 .packet_avail_size = NULL,      /* Would be racy anyway */
 879                 //.get_reader_wait_queue = lttng_get_reader_wait_queue,
 880                 //.get_hp_wait_queue = lttng_get_hp_wait_queue,
 881                 .is_finalized = lttng_is_finalized,
 882                 .is_disabled = lttng_is_disabled,
 883                 .flush_buffer = lttng_flush_buffer,
 884                 .event_strcpy = lttng_event_strcpy,
 885         },
 886         .client_config = &client_config,
 887 };
 888
 889 void RING_BUFFER_MODE_TEMPLATE_INIT(void)
 890 {
 891         DBG("LTT : ltt ring buffer client \"%s\" init\n",
 892                 "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap");
 893         lttng_transport_register(&lttng_relay_transport);
 894 }
 895
 896 void RING_BUFFER_MODE_TEMPLATE_EXIT(void)
 897 {
 898         DBG("LTT : ltt ring buffer client \"%s\" exit\n",
 899                 "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap");
 900         lttng_transport_unregister(&lttng_relay_transport);
 901 }