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

   1 /*
   2  * ltt-ring-buffer-client.h
   3  *
   4  * Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * LTTng lib ring buffer client template.
   7  *
   8  * Dual LGPL v2.1/GPL v2 license.
   9  */
  10
  11 #include <stdint.h>
  12 #include <lttng/ust-events.h>
  13 #include "lttng/bitfield.h"
  14 #include "clock.h"
  15 #include "uuid.h"
  16 #include "ltt-tracer.h"
  17 #include "../libringbuffer/frontend_types.h"
  18
  19 #define LTTNG_COMPACT_EVENT_BITS       5
  20 #define LTTNG_COMPACT_TSC_BITS         27
  21
  22 /*
  23  * Keep the natural field alignment for _each field_ within this structure if
  24  * you ever add/remove a field from this header. Packed attribute is not used
  25  * because gcc generates poor code on at least powerpc and mips. Don't ever
  26  * let gcc add padding between the structure elements.
  27  */
  28
  29 struct packet_header {
  30         /* Trace packet header */
  31         uint32_t magic;                 /*
  32                                          * Trace magic number.
  33                                          * contains endianness information.
  34                                          */
  35         uint8_t uuid[LTTNG_UST_UUID_LEN];
  36         uint32_t stream_id;
  37
  38         struct {
  39                 /* Stream packet context */
  40                 uint64_t timestamp_begin;       /* Cycle count at subbuffer start */
  41                 uint64_t timestamp_end;         /* Cycle count at subbuffer end */
  42                 uint32_t events_discarded;      /*
  43                                                  * Events lost in this subbuffer since
  44                                                  * the beginning of the trace.
  45                                                  * (may overflow)
  46                                                  */
  47                 uint32_t content_size;          /* Size of data in subbuffer */
  48                 uint32_t packet_size;           /* Subbuffer size (include padding) */
  49                 uint32_t cpu_id;                /* CPU id associated with stream */
  50                 uint8_t header_end;             /* End of header */
  51         } ctx;
  52 };
  53
  54
  55 static inline uint64_t lib_ring_buffer_clock_read(struct channel *chan)
  56 {
  57         return trace_clock_read64();
  58 }
  59
  60 static inline
  61 size_t ctx_get_size(size_t offset, struct lttng_ctx *ctx)
  62 {
  63         int i;
  64         size_t orig_offset = offset;
  65
  66         if (caa_likely(!ctx))
  67                 return 0;
  68         for (i = 0; i < ctx->nr_fields; i++)
  69                 offset += ctx->fields[i].get_size(offset);
  70         return offset - orig_offset;
  71 }
  72
  73 static inline
  74 void ctx_record(struct lttng_ust_lib_ring_buffer_ctx *bufctx,
  75                 struct ltt_channel *chan,
  76                 struct lttng_ctx *ctx)
  77 {
  78         int i;
  79
  80         if (caa_likely(!ctx))
  81                 return;
  82         for (i = 0; i < ctx->nr_fields; i++)
  83                 ctx->fields[i].record(&ctx->fields[i], bufctx, chan);
  84 }
  85
  86 /*
  87  * record_header_size - Calculate the header size and padding necessary.
  88  * @config: ring buffer instance configuration
  89  * @chan: channel
  90  * @offset: offset in the write buffer
  91  * @pre_header_padding: padding to add before the header (output)
  92  * @ctx: reservation context
  93  *
  94  * Returns the event header size (including padding).
  95  *
  96  * The payload must itself determine its own alignment from the biggest type it
  97  * contains.
  98  */
  99 static __inline__
 100 unsigned char record_header_size(const struct lttng_ust_lib_ring_buffer_config *config,
 101                                  struct channel *chan, size_t offset,
 102                                  size_t *pre_header_padding,
 103                                  struct lttng_ust_lib_ring_buffer_ctx *ctx)
 104 {
 105         struct ltt_channel *ltt_chan = channel_get_private(chan);
 106         struct ltt_event *event = ctx->priv;
 107         size_t orig_offset = offset;
 108         size_t padding;
 109
 110         switch (ltt_chan->header_type) {
 111         case 1: /* compact */
 112                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 113                 offset += padding;
 114                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 115                         offset += sizeof(uint32_t);     /* id and timestamp */
 116                 } else {
 117                         /* Minimum space taken by LTTNG_COMPACT_EVENT_BITS id */
 118                         offset += (LTTNG_COMPACT_EVENT_BITS + CHAR_BIT - 1) / CHAR_BIT;
 119                         /* Align extended struct on largest member */
 120                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 121                         offset += sizeof(uint32_t);     /* id */
 122                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 123                         offset += sizeof(uint64_t);     /* timestamp */
 124                 }
 125                 break;
 126         case 2: /* large */
 127                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint16_t));
 128                 offset += padding;
 129                 offset += sizeof(uint16_t);
 130                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 131                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 132                         offset += sizeof(uint32_t);     /* timestamp */
 133                 } else {
 134                         /* Align extended struct on largest member */
 135                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 136                         offset += sizeof(uint32_t);     /* id */
 137                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 138                         offset += sizeof(uint64_t);     /* timestamp */
 139                 }
 140                 break;
 141         default:
 142                 padding = 0;
 143                 WARN_ON_ONCE(1);
 144         }
 145         offset += ctx_get_size(offset, event->ctx);
 146         offset += ctx_get_size(offset, ltt_chan->ctx);
 147
 148         *pre_header_padding = padding;
 149         return offset - orig_offset;
 150 }
 151
 152 #include "../libringbuffer/api.h"
 153
 154 static
 155 void ltt_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config *config,
 156                                  struct lttng_ust_lib_ring_buffer_ctx *ctx,
 157                                  uint32_t event_id);
 158
 159 /*
 160  * ltt_write_event_header
 161  *
 162  * Writes the event header to the offset (already aligned on 32-bits).
 163  *
 164  * @config: ring buffer instance configuration
 165  * @ctx: reservation context
 166  * @event_id: event ID
 167  */
 168 static __inline__
 169 void ltt_write_event_header(const struct lttng_ust_lib_ring_buffer_config *config,
 170                             struct lttng_ust_lib_ring_buffer_ctx *ctx,
 171                             uint32_t event_id)
 172 {
 173         struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 174         struct ltt_event *event = ctx->priv;
 175
 176         if (caa_unlikely(ctx->rflags))
 177                 goto slow_path;
 178
 179         switch (ltt_chan->header_type) {
 180         case 1: /* compact */
 181         {
 182                 uint32_t id_time = 0;
 183
 184                 bt_bitfield_write(&id_time, uint32_t,
 185                                 0,
 186                                 LTTNG_COMPACT_EVENT_BITS,
 187                                 event_id);
 188                 bt_bitfield_write(&id_time, uint32_t,
 189                                 LTTNG_COMPACT_EVENT_BITS,
 190                                 LTTNG_COMPACT_TSC_BITS,
 191                                 ctx->tsc);
 192                 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 193                 break;
 194         }
 195         case 2: /* large */
 196         {
 197                 uint32_t timestamp = (uint32_t) ctx->tsc;
 198                 uint16_t id = event_id;
 199
 200                 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 201                 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 202                 lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 203                 break;
 204         }
 205         default:
 206                 WARN_ON_ONCE(1);
 207         }
 208
 209         ctx_record(ctx, ltt_chan, ltt_chan->ctx);
 210         ctx_record(ctx, ltt_chan, event->ctx);
 211         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 212
 213         return;
 214
 215 slow_path:
 216         ltt_write_event_header_slow(config, ctx, event_id);
 217 }
 218
 219 static
 220 void ltt_write_event_header_slow(const struct lttng_ust_lib_ring_buffer_config *config,
 221                                  struct lttng_ust_lib_ring_buffer_ctx *ctx,
 222                                  uint32_t event_id)
 223 {
 224         struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 225         struct ltt_event *event = ctx->priv;
 226
 227         switch (ltt_chan->header_type) {
 228         case 1: /* compact */
 229                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 230                         uint32_t id_time = 0;
 231
 232                         bt_bitfield_write(&id_time, uint32_t,
 233                                         0,
 234                                         LTTNG_COMPACT_EVENT_BITS,
 235                                         event_id);
 236                         bt_bitfield_write(&id_time, uint32_t,
 237                                         LTTNG_COMPACT_EVENT_BITS,
 238                                         LTTNG_COMPACT_TSC_BITS,
 239                                         ctx->tsc);
 240                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 241                 } else {
 242                         uint8_t id = 0;
 243                         uint64_t timestamp = ctx->tsc;
 244
 245                         bt_bitfield_write(&id, uint8_t,
 246                                         0,
 247                                         LTTNG_COMPACT_EVENT_BITS,
 248                                         31);
 249                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 250                         /* Align extended struct on largest member */
 251                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 252                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 253                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 254                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 255                 }
 256                 break;
 257         case 2: /* large */
 258         {
 259                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 260                         uint32_t timestamp = (uint32_t) ctx->tsc;
 261                         uint16_t id = event_id;
 262
 263                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 264                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 265                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 266                 } else {
 267                         uint16_t id = 65535;
 268                         uint64_t timestamp = ctx->tsc;
 269
 270                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 271                         /* Align extended struct on largest member */
 272                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 273                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 274                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 275                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 276                 }
 277                 break;
 278         }
 279         default:
 280                 WARN_ON_ONCE(1);
 281         }
 282         ctx_record(ctx, ltt_chan, ltt_chan->ctx);
 283         ctx_record(ctx, ltt_chan, event->ctx);
 284         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 285 }
 286
 287 static const struct lttng_ust_lib_ring_buffer_config client_config;
 288
 289 static uint64_t client_ring_buffer_clock_read(struct channel *chan)
 290 {
 291         return lib_ring_buffer_clock_read(chan);
 292 }
 293
 294 static
 295 size_t client_record_header_size(const struct lttng_ust_lib_ring_buffer_config *config,
 296                                  struct channel *chan, size_t offset,
 297                                  size_t *pre_header_padding,
 298                                  struct lttng_ust_lib_ring_buffer_ctx *ctx)
 299 {
 300         return record_header_size(config, chan, offset,
 301                                   pre_header_padding, ctx);
 302 }
 303
 304 /**
 305  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 306  *
 307  * Return header size without padding after the structure. Don't use packed
 308  * structure because gcc generates inefficient code on some architectures
 309  * (powerpc, mips..)
 310  */
 311 static size_t client_packet_header_size(void)
 312 {
 313         return offsetof(struct packet_header, ctx.header_end);
 314 }
 315
 316 static void client_buffer_begin(struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
 317                                 unsigned int subbuf_idx,
 318                                 struct lttng_ust_shm_handle *handle)
 319 {
 320         struct channel *chan = shmp(handle, buf->backend.chan);
 321         struct packet_header *header =
 322                 (struct packet_header *)
 323                         lib_ring_buffer_offset_address(&buf->backend,
 324                                 subbuf_idx * chan->backend.subbuf_size,
 325                                 handle);
 326         struct ltt_channel *ltt_chan = channel_get_private(chan);
 327
 328         header->magic = CTF_MAGIC_NUMBER;
 329         memcpy(header->uuid, ltt_chan->uuid, sizeof(ltt_chan->uuid));
 330         header->stream_id = ltt_chan->id;
 331         header->ctx.timestamp_begin = tsc;
 332         header->ctx.timestamp_end = 0;
 333         header->ctx.events_discarded = 0;
 334         header->ctx.content_size = 0xFFFFFFFF; /* for debugging */
 335         header->ctx.packet_size = 0xFFFFFFFF;
 336         header->ctx.cpu_id = buf->backend.cpu;
 337 }
 338
 339 /*
 340  * offset is assumed to never be 0 here : never deliver a completely empty
 341  * subbuffer. data_size is between 1 and subbuf_size.
 342  */
 343 static void client_buffer_end(struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc,
 344                               unsigned int subbuf_idx, unsigned long data_size,
 345                               struct lttng_ust_shm_handle *handle)
 346 {
 347         struct channel *chan = shmp(handle, buf->backend.chan);
 348         struct packet_header *header =
 349                 (struct packet_header *)
 350                         lib_ring_buffer_offset_address(&buf->backend,
 351                                 subbuf_idx * chan->backend.subbuf_size,
 352                                 handle);
 353         unsigned long records_lost = 0;
 354
 355         header->ctx.timestamp_end = tsc;
 356         header->ctx.content_size = data_size * CHAR_BIT;        /* in bits */
 357         header->ctx.packet_size = PAGE_ALIGN(data_size) * CHAR_BIT; /* in bits */
 358         /*
 359          * We do not care about the records lost count, because the metadata
 360          * channel waits and retry.
 361          */
 362         (void) lib_ring_buffer_get_records_lost_full(&client_config, buf);
 363         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 364         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 365         header->ctx.events_discarded = records_lost;
 366 }
 367
 368 static int client_buffer_create(struct lttng_ust_lib_ring_buffer *buf, void *priv,
 369                                 int cpu, const char *name, struct lttng_ust_shm_handle *handle)
 370 {
 371         return 0;
 372 }
 373
 374 static void client_buffer_finalize(struct lttng_ust_lib_ring_buffer *buf, void *priv, int cpu, struct lttng_ust_shm_handle *handle)
 375 {
 376 }
 377
 378 static const struct lttng_ust_lib_ring_buffer_config client_config = {
 379         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 380         .cb.record_header_size = client_record_header_size,
 381         .cb.subbuffer_header_size = client_packet_header_size,
 382         .cb.buffer_begin = client_buffer_begin,
 383         .cb.buffer_end = client_buffer_end,
 384         .cb.buffer_create = client_buffer_create,
 385         .cb.buffer_finalize = client_buffer_finalize,
 386
 387         .tsc_bits = LTTNG_COMPACT_TSC_BITS,
 388         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 389         .sync = RING_BUFFER_SYNC_GLOBAL,
 390         .mode = RING_BUFFER_MODE_TEMPLATE,
 391         .backend = RING_BUFFER_PAGE,
 392         .output = RING_BUFFER_MMAP,
 393         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 394         .ipi = RING_BUFFER_NO_IPI_BARRIER,
 395         .wakeup = RING_BUFFER_WAKEUP_BY_WRITER,
 396         .client_type = LTTNG_CLIENT_TYPE,
 397 };
 398
 399 const struct lttng_ust_lib_ring_buffer_client_cb *LTTNG_CLIENT_CALLBACKS = &client_config.cb;
 400
 401 static
 402 struct ltt_channel *_channel_create(const char *name,
 403                                 void *buf_addr,
 404                                 size_t subbuf_size, size_t num_subbuf,
 405                                 unsigned int switch_timer_interval,
 406                                 unsigned int read_timer_interval,
 407                                 int **shm_fd, int **wait_fd,
 408                                 uint64_t **memory_map_size,
 409                                 struct ltt_channel *chan_priv_init)
 410 {
 411         void *priv;
 412         struct ltt_channel *ltt_chan = NULL;
 413         struct lttng_ust_shm_handle *handle;
 414
 415         handle = channel_create(&client_config, name,
 416                         &priv, __alignof__(*ltt_chan), sizeof(*ltt_chan),
 417                         chan_priv_init,
 418                         buf_addr, subbuf_size, num_subbuf,
 419                         switch_timer_interval, read_timer_interval,
 420                         shm_fd, wait_fd, memory_map_size);
 421         if (!handle)
 422                 return NULL;
 423         ltt_chan = priv;
 424         ltt_chan->handle = handle;
 425         ltt_chan->chan = shmp(ltt_chan->handle, ltt_chan->handle->chan);
 426         return ltt_chan;
 427 }
 428
 429 static
 430 void ltt_channel_destroy(struct ltt_channel *ltt_chan)
 431 {
 432         channel_destroy(ltt_chan->chan, ltt_chan->handle, 0);
 433 }
 434
 435 static
 436 struct lttng_ust_lib_ring_buffer *ltt_buffer_read_open(struct channel *chan,
 437                                              struct lttng_ust_shm_handle *handle,
 438                                              int **shm_fd, int **wait_fd,
 439                                              uint64_t **memory_map_size)
 440 {
 441         struct lttng_ust_lib_ring_buffer *buf;
 442         int cpu;
 443
 444         for_each_channel_cpu(cpu, chan) {
 445                 buf = channel_get_ring_buffer(&client_config, chan,
 446                                 cpu, handle, shm_fd, wait_fd,
 447                                 memory_map_size);
 448                 if (!lib_ring_buffer_open_read(buf, handle, 0))
 449                         return buf;
 450         }
 451         return NULL;
 452 }
 453
 454 static
 455 void ltt_buffer_read_close(struct lttng_ust_lib_ring_buffer *buf,
 456                            struct lttng_ust_shm_handle *handle)
 457 {
 458         lib_ring_buffer_release_read(buf, handle, 0);
 459 }
 460
 461 static
 462 int ltt_event_reserve(struct lttng_ust_lib_ring_buffer_ctx *ctx,
 463                       uint32_t event_id)
 464 {
 465         struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 466         int ret, cpu;
 467
 468         cpu = lib_ring_buffer_get_cpu(&client_config);
 469         if (cpu < 0)
 470                 return -EPERM;
 471         ctx->cpu = cpu;
 472
 473         switch (ltt_chan->header_type) {
 474         case 1: /* compact */
 475                 if (event_id > 30)
 476                         ctx->rflags |= LTT_RFLAG_EXTENDED;
 477                 break;
 478         case 2: /* large */
 479                 if (event_id > 65534)
 480                         ctx->rflags |= LTT_RFLAG_EXTENDED;
 481                 break;
 482         default:
 483                 WARN_ON_ONCE(1);
 484         }
 485
 486         ret = lib_ring_buffer_reserve(&client_config, ctx);
 487         if (ret)
 488                 goto put;
 489         ltt_write_event_header(&client_config, ctx, event_id);
 490         return 0;
 491 put:
 492         lib_ring_buffer_put_cpu(&client_config);
 493         return ret;
 494 }
 495
 496 static
 497 void ltt_event_commit(struct lttng_ust_lib_ring_buffer_ctx *ctx)
 498 {
 499         lib_ring_buffer_commit(&client_config, ctx);
 500         lib_ring_buffer_put_cpu(&client_config);
 501 }
 502
 503 static
 504 void ltt_event_write(struct lttng_ust_lib_ring_buffer_ctx *ctx, const void *src,
 505                      size_t len)
 506 {
 507         lib_ring_buffer_write(&client_config, ctx, src, len);
 508 }
 509
 510 #if 0
 511 static
 512 wait_queue_head_t *ltt_get_reader_wait_queue(struct channel *chan)
 513 {
 514         return &chan->read_wait;
 515 }
 516
 517 static
 518 wait_queue_head_t *ltt_get_hp_wait_queue(struct channel *chan)
 519 {
 520         return &chan->hp_wait;
 521 }
 522 #endif //0
 523
 524 static
 525 int ltt_is_finalized(struct channel *chan)
 526 {
 527         return lib_ring_buffer_channel_is_finalized(chan);
 528 }
 529
 530 static
 531 int ltt_is_disabled(struct channel *chan)
 532 {
 533         return lib_ring_buffer_channel_is_disabled(chan);
 534 }
 535
 536 static
 537 int ltt_flush_buffer(struct channel *chan, struct lttng_ust_shm_handle *handle)
 538 {
 539         struct lttng_ust_lib_ring_buffer *buf;
 540         int cpu;
 541
 542         for_each_channel_cpu(cpu, chan) {
 543                 int *shm_fd, *wait_fd;
 544                 uint64_t *memory_map_size;
 545
 546                 buf = channel_get_ring_buffer(&client_config, chan,
 547                                 cpu, handle, &shm_fd, &wait_fd,
 548                                 &memory_map_size);
 549                 lib_ring_buffer_switch(&client_config, buf,
 550                                 SWITCH_ACTIVE, handle);
 551         }
 552         return 0;
 553 }
 554
 555 static struct ltt_transport ltt_relay_transport = {
 556         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING "-mmap",
 557         .ops = {
 558                 .channel_create = _channel_create,
 559                 .channel_destroy = ltt_channel_destroy,
 560                 .buffer_read_open = ltt_buffer_read_open,
 561                 .buffer_read_close = ltt_buffer_read_close,
 562                 .event_reserve = ltt_event_reserve,
 563                 .event_commit = ltt_event_commit,
 564                 .event_write = ltt_event_write,
 565                 .packet_avail_size = NULL,      /* Would be racy anyway */
 566                 //.get_reader_wait_queue = ltt_get_reader_wait_queue,
 567                 //.get_hp_wait_queue = ltt_get_hp_wait_queue,
 568                 .is_finalized = ltt_is_finalized,
 569                 .is_disabled = ltt_is_disabled,
 570                 .flush_buffer = ltt_flush_buffer,
 571         },
 572 };
 573
 574 void RING_BUFFER_MODE_TEMPLATE_INIT(void)
 575 {
 576         DBG("LTT : ltt ring buffer client init\n");
 577         ltt_transport_register(&ltt_relay_transport);
 578 }
 579
 580 void RING_BUFFER_MODE_TEMPLATE_EXIT(void)
 581 {
 582         DBG("LTT : ltt ring buffer client exit\n");
 583         ltt_transport_unregister(&ltt_relay_transport);
 584 }