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