lttng-ring-buffer-client.h

   1 /*
   2  * lttng-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 <linux/module.h>
  12 #include <linux/types.h>
  13 #include "lib/bitfield.h"
  14 #include "wrapper/vmalloc.h"    /* for wrapper_vmalloc_sync_all() */
  15 #include "wrapper/trace-clock.h"
  16 #include "lttng-events.h"
  17 #include "lttng-tracer.h"
  18 #include "wrapper/ringbuffer/frontend_types.h"
  19
  20 #define LTTNG_COMPACT_EVENT_BITS        5
  21 #define LTTNG_COMPACT_TSC_BITS          27
  22
  23 /*
  24  * Keep the natural field alignment for _each field_ within this structure if
  25  * you ever add/remove a field from this header. Packed attribute is not used
  26  * because gcc generates poor code on at least powerpc and mips. Don't ever
  27  * let gcc add padding between the structure elements.
  28  *
  29  * The guarantee we have with timestamps is that all the events in a
  30  * packet are included (inclusive) within the begin/end timestamps of
  31  * the packet. Another guarantee we have is that the "timestamp begin",
  32  * as well as the event timestamps, are monotonically increasing (never
  33  * decrease) when moving forward in a stream (physically). But this
  34  * guarantee does not apply to "timestamp end", because it is sampled at
  35  * commit time, which is not ordered with respect to space reservation.
  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[16];
  45         uint32_t stream_id;
  46
  47         struct {
  48                 /* Stream packet context */
  49                 uint64_t timestamp_begin;       /* Cycle count at subbuffer start */
  50                 uint64_t timestamp_end;         /* Cycle count at subbuffer end */
  51                 uint32_t events_discarded;      /*
  52                                                  * Events lost in this subbuffer since
  53                                                  * the beginning of the trace.
  54                                                  * (may overflow)
  55                                                  */
  56                 uint32_t content_size;          /* Size of data in subbuffer */
  57                 uint32_t packet_size;           /* Subbuffer size (include padding) */
  58                 uint32_t cpu_id;                /* CPU id associated with stream */
  59                 uint8_t header_end;             /* End of header */
  60         } ctx;
  61 };
  62
  63
  64 static inline notrace u64 lib_ring_buffer_clock_read(struct channel *chan)
  65 {
  66         return trace_clock_read64();
  67 }
  68
  69 static inline
  70 size_t ctx_get_size(size_t offset, struct lttng_ctx *ctx)
  71 {
  72         int i;
  73         size_t orig_offset = offset;
  74
  75         if (likely(!ctx))
  76                 return 0;
  77         for (i = 0; i < ctx->nr_fields; i++)
  78                 offset += ctx->fields[i].get_size(offset);
  79         return offset - orig_offset;
  80 }
  81
  82 static inline
  83 void ctx_record(struct lib_ring_buffer_ctx *bufctx,
  84                 struct lttng_channel *chan,
  85                 struct lttng_ctx *ctx)
  86 {
  87         int i;
  88
  89         if (likely(!ctx))
  90                 return;
  91         for (i = 0; i < ctx->nr_fields; i++)
  92                 ctx->fields[i].record(&ctx->fields[i], bufctx, chan);
  93 }
  94
  95 /*
  96  * record_header_size - Calculate the header size and padding necessary.
  97  * @config: ring buffer instance configuration
  98  * @chan: channel
  99  * @offset: offset in the write buffer
 100  * @pre_header_padding: padding to add before the header (output)
 101  * @ctx: reservation context
 102  *
 103  * Returns the event header size (including padding).
 104  *
 105  * The payload must itself determine its own alignment from the biggest type it
 106  * contains.
 107  */
 108 static __inline__
 109 unsigned char record_header_size(const struct lib_ring_buffer_config *config,
 110                                  struct channel *chan, size_t offset,
 111                                  size_t *pre_header_padding,
 112                                  struct lib_ring_buffer_ctx *ctx)
 113 {
 114         struct lttng_channel *lttng_chan = channel_get_private(chan);
 115         struct lttng_event *event = ctx->priv;
 116         size_t orig_offset = offset;
 117         size_t padding;
 118
 119         switch (lttng_chan->header_type) {
 120         case 1: /* compact */
 121                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 122                 offset += padding;
 123                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 124                         offset += sizeof(uint32_t);     /* id and timestamp */
 125                 } else {
 126                         /* Minimum space taken by LTTNG_COMPACT_EVENT_BITS id */
 127                         offset += (LTTNG_COMPACT_EVENT_BITS + CHAR_BIT - 1) / CHAR_BIT;
 128                         /* Align extended struct on largest member */
 129                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 130                         offset += sizeof(uint32_t);     /* id */
 131                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 132                         offset += sizeof(uint64_t);     /* timestamp */
 133                 }
 134                 break;
 135         case 2: /* large */
 136                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint16_t));
 137                 offset += padding;
 138                 offset += sizeof(uint16_t);
 139                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 140                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 141                         offset += sizeof(uint32_t);     /* timestamp */
 142                 } else {
 143                         /* Align extended struct on largest member */
 144                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 145                         offset += sizeof(uint32_t);     /* id */
 146                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 147                         offset += sizeof(uint64_t);     /* timestamp */
 148                 }
 149                 break;
 150         default:
 151                 padding = 0;
 152                 WARN_ON_ONCE(1);
 153         }
 154         offset += ctx_get_size(offset, event->ctx);
 155         offset += ctx_get_size(offset, lttng_chan->ctx);
 156
 157         *pre_header_padding = padding;
 158         return offset - orig_offset;
 159 }
 160
 161 #include "wrapper/ringbuffer/api.h"
 162
 163 static
 164 void lttng_write_event_header_slow(const struct lib_ring_buffer_config *config,
 165                                  struct lib_ring_buffer_ctx *ctx,
 166                                  uint32_t event_id);
 167
 168 /*
 169  * lttng_write_event_header
 170  *
 171  * Writes the event header to the offset (already aligned on 32-bits).
 172  *
 173  * @config: ring buffer instance configuration
 174  * @ctx: reservation context
 175  * @event_id: event ID
 176  */
 177 static __inline__
 178 void lttng_write_event_header(const struct lib_ring_buffer_config *config,
 179                             struct lib_ring_buffer_ctx *ctx,
 180                             uint32_t event_id)
 181 {
 182         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 183         struct lttng_event *event = ctx->priv;
 184
 185         if (unlikely(ctx->rflags))
 186                 goto slow_path;
 187
 188         switch (lttng_chan->header_type) {
 189         case 1: /* compact */
 190         {
 191                 uint32_t id_time = 0;
 192
 193                 bt_bitfield_write(&id_time, uint32_t,
 194                                 0,
 195                                 LTTNG_COMPACT_EVENT_BITS,
 196                                 event_id);
 197                 bt_bitfield_write(&id_time, uint32_t,
 198                                 LTTNG_COMPACT_EVENT_BITS,
 199                                 LTTNG_COMPACT_TSC_BITS,
 200                                 ctx->tsc);
 201                 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 202                 break;
 203         }
 204         case 2: /* large */
 205         {
 206                 uint32_t timestamp = (uint32_t) ctx->tsc;
 207                 uint16_t id = event_id;
 208
 209                 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 210                 lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 211                 lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 212                 break;
 213         }
 214         default:
 215                 WARN_ON_ONCE(1);
 216         }
 217
 218         ctx_record(ctx, lttng_chan, lttng_chan->ctx);
 219         ctx_record(ctx, lttng_chan, event->ctx);
 220         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 221
 222         return;
 223
 224 slow_path:
 225         lttng_write_event_header_slow(config, ctx, event_id);
 226 }
 227
 228 static
 229 void lttng_write_event_header_slow(const struct lib_ring_buffer_config *config,
 230                                  struct lib_ring_buffer_ctx *ctx,
 231                                  uint32_t event_id)
 232 {
 233         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 234         struct lttng_event *event = ctx->priv;
 235
 236         switch (lttng_chan->header_type) {
 237         case 1: /* compact */
 238                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 239                         uint32_t id_time = 0;
 240
 241                         bt_bitfield_write(&id_time, uint32_t,
 242                                         0,
 243                                         LTTNG_COMPACT_EVENT_BITS,
 244                                         event_id);
 245                         bt_bitfield_write(&id_time, uint32_t,
 246                                         LTTNG_COMPACT_EVENT_BITS,
 247                                         LTTNG_COMPACT_TSC_BITS, ctx->tsc);
 248                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 249                 } else {
 250                         uint8_t id = 0;
 251                         uint64_t timestamp = ctx->tsc;
 252
 253                         bt_bitfield_write(&id, uint8_t,
 254                                         0,
 255                                         LTTNG_COMPACT_EVENT_BITS,
 256                                         31);
 257                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 258                         /* Align extended struct on largest member */
 259                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 260                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 261                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 262                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 263                 }
 264                 break;
 265         case 2: /* large */
 266         {
 267                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 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                 } else {
 275                         uint16_t id = 65535;
 276                         uint64_t timestamp = ctx->tsc;
 277
 278                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 279                         /* Align extended struct on largest member */
 280                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 281                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 282                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 283                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 284                 }
 285                 break;
 286         }
 287         default:
 288                 WARN_ON_ONCE(1);
 289         }
 290         ctx_record(ctx, lttng_chan, lttng_chan->ctx);
 291         ctx_record(ctx, lttng_chan, event->ctx);
 292         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 293 }
 294
 295 static const struct lib_ring_buffer_config client_config;
 296
 297 static u64 client_ring_buffer_clock_read(struct channel *chan)
 298 {
 299         return lib_ring_buffer_clock_read(chan);
 300 }
 301
 302 static
 303 size_t client_record_header_size(const struct lib_ring_buffer_config *config,
 304                                  struct channel *chan, size_t offset,
 305                                  size_t *pre_header_padding,
 306                                  struct lib_ring_buffer_ctx *ctx)
 307 {
 308         return record_header_size(config, chan, offset,
 309                                   pre_header_padding, ctx);
 310 }
 311
 312 /**
 313  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 314  *
 315  * Return header size without padding after the structure. Don't use packed
 316  * structure because gcc generates inefficient code on some architectures
 317  * (powerpc, mips..)
 318  */
 319 static size_t client_packet_header_size(void)
 320 {
 321         return offsetof(struct packet_header, ctx.header_end);
 322 }
 323
 324 static void client_buffer_begin(struct lib_ring_buffer *buf, u64 tsc,
 325                                 unsigned int subbuf_idx)
 326 {
 327         struct channel *chan = buf->backend.chan;
 328         struct packet_header *header =
 329                 (struct packet_header *)
 330                         lib_ring_buffer_offset_address(&buf->backend,
 331                                 subbuf_idx * chan->backend.subbuf_size);
 332         struct lttng_channel *lttng_chan = channel_get_private(chan);
 333         struct lttng_session *session = lttng_chan->session;
 334
 335         header->magic = CTF_MAGIC_NUMBER;
 336         memcpy(header->uuid, session->uuid.b, sizeof(session->uuid));
 337         header->stream_id = lttng_chan->id;
 338         header->ctx.timestamp_begin = tsc;
 339         header->ctx.timestamp_end = 0;
 340         header->ctx.events_discarded = 0;
 341         header->ctx.content_size = 0xFFFFFFFF; /* for debugging */
 342         header->ctx.packet_size = 0xFFFFFFFF;
 343         header->ctx.cpu_id = buf->backend.cpu;
 344 }
 345
 346 /*
 347  * offset is assumed to never be 0 here : never deliver a completely empty
 348  * subbuffer. data_size is between 1 and subbuf_size.
 349  */
 350 static void client_buffer_end(struct lib_ring_buffer *buf, u64 tsc,
 351                               unsigned int subbuf_idx, unsigned long data_size)
 352 {
 353         struct channel *chan = buf->backend.chan;
 354         struct packet_header *header =
 355                 (struct packet_header *)
 356                         lib_ring_buffer_offset_address(&buf->backend,
 357                                 subbuf_idx * chan->backend.subbuf_size);
 358         unsigned long records_lost = 0;
 359
 360         header->ctx.timestamp_end = tsc;
 361         header->ctx.content_size = data_size * CHAR_BIT;        /* in bits */
 362         header->ctx.packet_size = PAGE_ALIGN(data_size) * CHAR_BIT; /* in bits */
 363         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
 364         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 365         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 366         header->ctx.events_discarded = records_lost;
 367 }
 368
 369 static int client_buffer_create(struct lib_ring_buffer *buf, void *priv,
 370                                 int cpu, const char *name)
 371 {
 372         return 0;
 373 }
 374
 375 static void client_buffer_finalize(struct lib_ring_buffer *buf, void *priv, int cpu)
 376 {
 377 }
 378
 379 static const struct lib_ring_buffer_config client_config = {
 380         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 381         .cb.record_header_size = client_record_header_size,
 382         .cb.subbuffer_header_size = client_packet_header_size,
 383         .cb.buffer_begin = client_buffer_begin,
 384         .cb.buffer_end = client_buffer_end,
 385         .cb.buffer_create = client_buffer_create,
 386         .cb.buffer_finalize = client_buffer_finalize,
 387
 388         .tsc_bits = LTTNG_COMPACT_TSC_BITS,
 389         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 390         .sync = RING_BUFFER_SYNC_PER_CPU,
 391         .mode = RING_BUFFER_MODE_TEMPLATE,
 392         .backend = RING_BUFFER_PAGE,
 393         .output = RING_BUFFER_OUTPUT_TEMPLATE,
 394         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 395         .ipi = RING_BUFFER_IPI_BARRIER,
 396         .wakeup = RING_BUFFER_WAKEUP_BY_TIMER,
 397 };
 398
 399 static
 400 struct channel *_channel_create(const char *name,
 401                                 struct lttng_channel *lttng_chan, void *buf_addr,
 402                                 size_t subbuf_size, size_t num_subbuf,
 403                                 unsigned int switch_timer_interval,
 404                                 unsigned int read_timer_interval)
 405 {
 406         return channel_create(&client_config, name, lttng_chan, buf_addr,
 407                               subbuf_size, num_subbuf, switch_timer_interval,
 408                               read_timer_interval);
 409 }
 410
 411 static
 412 void lttng_channel_destroy(struct channel *chan)
 413 {
 414         channel_destroy(chan);
 415 }
 416
 417 static
 418 struct lib_ring_buffer *lttng_buffer_read_open(struct channel *chan)
 419 {
 420         struct lib_ring_buffer *buf;
 421         int cpu;
 422
 423         for_each_channel_cpu(cpu, chan) {
 424                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 425                 if (!lib_ring_buffer_open_read(buf))
 426                         return buf;
 427         }
 428         return NULL;
 429 }
 430
 431 static
 432 int lttng_buffer_has_read_closed_stream(struct channel *chan)
 433 {
 434         struct lib_ring_buffer *buf;
 435         int cpu;
 436
 437         for_each_channel_cpu(cpu, chan) {
 438                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 439                 if (!atomic_long_read(&buf->active_readers))
 440                         return 1;
 441         }
 442         return 0;
 443 }
 444
 445 static
 446 void lttng_buffer_read_close(struct lib_ring_buffer *buf)
 447 {
 448         lib_ring_buffer_release_read(buf);
 449 }
 450
 451 static
 452 int lttng_event_reserve(struct lib_ring_buffer_ctx *ctx,
 453                       uint32_t event_id)
 454 {
 455         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 456         int ret, cpu;
 457
 458         cpu = lib_ring_buffer_get_cpu(&client_config);
 459         if (cpu < 0)
 460                 return -EPERM;
 461         ctx->cpu = cpu;
 462
 463         switch (lttng_chan->header_type) {
 464         case 1: /* compact */
 465                 if (event_id > 30)
 466                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 467                 break;
 468         case 2: /* large */
 469                 if (event_id > 65534)
 470                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 471                 break;
 472         default:
 473                 WARN_ON_ONCE(1);
 474         }
 475
 476         ret = lib_ring_buffer_reserve(&client_config, ctx);
 477         if (ret)
 478                 goto put;
 479         lttng_write_event_header(&client_config, ctx, event_id);
 480         return 0;
 481 put:
 482         lib_ring_buffer_put_cpu(&client_config);
 483         return ret;
 484 }
 485
 486 static
 487 void lttng_event_commit(struct lib_ring_buffer_ctx *ctx)
 488 {
 489         lib_ring_buffer_commit(&client_config, ctx);
 490         lib_ring_buffer_put_cpu(&client_config);
 491 }
 492
 493 static
 494 void lttng_event_write(struct lib_ring_buffer_ctx *ctx, const void *src,
 495                      size_t len)
 496 {
 497         lib_ring_buffer_write(&client_config, ctx, src, len);
 498 }
 499
 500 static
 501 void lttng_event_write_from_user(struct lib_ring_buffer_ctx *ctx,
 502                                const void __user *src, size_t len)
 503 {
 504         lib_ring_buffer_copy_from_user(&client_config, ctx, src, len);
 505 }
 506
 507 static
 508 void lttng_event_memset(struct lib_ring_buffer_ctx *ctx,
 509                 int c, size_t len)
 510 {
 511         lib_ring_buffer_memset(&client_config, ctx, c, len);
 512 }
 513
 514 static
 515 wait_queue_head_t *lttng_get_writer_buf_wait_queue(struct channel *chan, int cpu)
 516 {
 517         struct lib_ring_buffer *buf = channel_get_ring_buffer(&client_config,
 518                                         chan, cpu);
 519         return &buf->write_wait;
 520 }
 521
 522 static
 523 wait_queue_head_t *lttng_get_hp_wait_queue(struct channel *chan)
 524 {
 525         return &chan->hp_wait;
 526 }
 527
 528 static
 529 int lttng_is_finalized(struct channel *chan)
 530 {
 531         return lib_ring_buffer_channel_is_finalized(chan);
 532 }
 533
 534 static
 535 int lttng_is_disabled(struct channel *chan)
 536 {
 537         return lib_ring_buffer_channel_is_disabled(chan);
 538 }
 539
 540 static struct lttng_transport lttng_relay_transport = {
 541         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
 542         .owner = THIS_MODULE,
 543         .ops = {
 544                 .channel_create = _channel_create,
 545                 .channel_destroy = lttng_channel_destroy,
 546                 .buffer_read_open = lttng_buffer_read_open,
 547                 .buffer_has_read_closed_stream =
 548                         lttng_buffer_has_read_closed_stream,
 549                 .buffer_read_close = lttng_buffer_read_close,
 550                 .event_reserve = lttng_event_reserve,
 551                 .event_commit = lttng_event_commit,
 552                 .event_write = lttng_event_write,
 553                 .event_write_from_user = lttng_event_write_from_user,
 554                 .event_memset = lttng_event_memset,
 555                 .packet_avail_size = NULL,      /* Would be racy anyway */
 556                 .get_writer_buf_wait_queue = lttng_get_writer_buf_wait_queue,
 557                 .get_hp_wait_queue = lttng_get_hp_wait_queue,
 558                 .is_finalized = lttng_is_finalized,
 559                 .is_disabled = lttng_is_disabled,
 560         },
 561 };
 562
 563 static int __init lttng_ring_buffer_client_init(void)
 564 {
 565         /*
 566          * This vmalloc sync all also takes care of the lib ring buffer
 567          * vmalloc'd module pages when it is built as a module into LTTng.
 568          */
 569         wrapper_vmalloc_sync_all();
 570         lttng_transport_register(&lttng_relay_transport);
 571         return 0;
 572 }
 573
 574 module_init(lttng_ring_buffer_client_init);
 575
 576 static void __exit lttng_ring_buffer_client_exit(void)
 577 {
 578         lttng_transport_unregister(&lttng_relay_transport);
 579 }
 580
 581 module_exit(lttng_ring_buffer_client_exit);
 582
 583 MODULE_LICENSE("GPL and additional rights");
 584 MODULE_AUTHOR("Mathieu Desnoyers");
 585 MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING
 586                    " client");