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 /*
  21  * Keep the natural field alignment for _each field_ within this structure if
  22  * you ever add/remove a field from this header. Packed attribute is not used
  23  * because gcc generates poor code on at least powerpc and mips. Don't ever
  24  * let gcc add padding between the structure elements.
  25  *
  26  * The guarantee we have with timestamps is that all the events in a
  27  * packet are included (inclusive) within the begin/end timestamps of
  28  * the packet. Another guarantee we have is that the "timestamp begin",
  29  * as well as the event timestamps, are monotonically increasing (never
  30  * decrease) when moving forward in a stream (physically). But this
  31  * guarantee does not apply to "timestamp end", because it is sampled at
  32  * commit time, which is not ordered with respect to space reservation.
  33  */
  34
  35 struct packet_header {
  36         /* Trace packet header */
  37         uint32_t magic;                 /*
  38                                          * Trace magic number.
  39                                          * contains endianness information.
  40                                          */
  41         uint8_t uuid[16];
  42         uint32_t stream_id;
  43
  44         struct {
  45                 /* Stream packet context */
  46                 uint64_t timestamp_begin;       /* Cycle count at subbuffer start */
  47                 uint64_t timestamp_end;         /* Cycle count at subbuffer end */
  48                 uint32_t events_discarded;      /*
  49                                                  * Events lost in this subbuffer since
  50                                                  * the beginning of the trace.
  51                                                  * (may overflow)
  52                                                  */
  53                 uint32_t content_size;          /* Size of data in subbuffer */
  54                 uint32_t packet_size;           /* Subbuffer size (include padding) */
  55                 uint32_t cpu_id;                /* CPU id associated with stream */
  56                 uint8_t header_end;             /* End of header */
  57         } ctx;
  58 };
  59
  60
  61 static inline notrace u64 lib_ring_buffer_clock_read(struct channel *chan)
  62 {
  63         return trace_clock_read64();
  64 }
  65
  66 static inline
  67 size_t ctx_get_size(size_t offset, struct lttng_ctx *ctx)
  68 {
  69         int i;
  70         size_t orig_offset = offset;
  71
  72         if (likely(!ctx))
  73                 return 0;
  74         for (i = 0; i < ctx->nr_fields; i++)
  75                 offset += ctx->fields[i].get_size(offset);
  76         return offset - orig_offset;
  77 }
  78
  79 static inline
  80 void ctx_record(struct lib_ring_buffer_ctx *bufctx,
  81                 struct lttng_channel *chan,
  82                 struct lttng_ctx *ctx)
  83 {
  84         int i;
  85
  86         if (likely(!ctx))
  87                 return;
  88         for (i = 0; i < ctx->nr_fields; i++)
  89                 ctx->fields[i].record(&ctx->fields[i], bufctx, chan);
  90 }
  91
  92 /*
  93  * record_header_size - Calculate the header size and padding necessary.
  94  * @config: ring buffer instance configuration
  95  * @chan: channel
  96  * @offset: offset in the write buffer
  97  * @pre_header_padding: padding to add before the header (output)
  98  * @ctx: reservation context
  99  *
 100  * Returns the event header size (including padding).
 101  *
 102  * The payload must itself determine its own alignment from the biggest type it
 103  * contains.
 104  */
 105 static __inline__
 106 unsigned char record_header_size(const struct lib_ring_buffer_config *config,
 107                                  struct channel *chan, size_t offset,
 108                                  size_t *pre_header_padding,
 109                                  struct lib_ring_buffer_ctx *ctx)
 110 {
 111         struct lttng_channel *lttng_chan = channel_get_private(chan);
 112         struct lttng_event *event = ctx->priv;
 113         size_t orig_offset = offset;
 114         size_t padding;
 115
 116         switch (lttng_chan->header_type) {
 117         case 1: /* compact */
 118                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 119                 offset += padding;
 120                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 121                         offset += sizeof(uint32_t);     /* id and timestamp */
 122                 } else {
 123                         /* Minimum space taken by 5-bit id */
 124                         offset += sizeof(uint8_t);
 125                         /* Align extended struct on largest member */
 126                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 127                         offset += sizeof(uint32_t);     /* id */
 128                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 129                         offset += sizeof(uint64_t);     /* timestamp */
 130                 }
 131                 break;
 132         case 2: /* large */
 133                 padding = lib_ring_buffer_align(offset, lttng_alignof(uint16_t));
 134                 offset += padding;
 135                 offset += sizeof(uint16_t);
 136                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 137                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
 138                         offset += sizeof(uint32_t);     /* timestamp */
 139                 } else {
 140                         /* Align extended struct on largest member */
 141                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 142                         offset += sizeof(uint32_t);     /* id */
 143                         offset += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
 144                         offset += sizeof(uint64_t);     /* timestamp */
 145                 }
 146                 break;
 147         default:
 148                 padding = 0;
 149                 WARN_ON_ONCE(1);
 150         }
 151         offset += ctx_get_size(offset, event->ctx);
 152         offset += ctx_get_size(offset, lttng_chan->ctx);
 153
 154         *pre_header_padding = padding;
 155         return offset - orig_offset;
 156 }
 157
 158 #include "wrapper/ringbuffer/api.h"
 159
 160 static
 161 void lttng_write_event_header_slow(const struct lib_ring_buffer_config *config,
 162                                  struct lib_ring_buffer_ctx *ctx,
 163                                  uint32_t event_id);
 164
 165 /*
 166  * lttng_write_event_header
 167  *
 168  * Writes the event header to the offset (already aligned on 32-bits).
 169  *
 170  * @config: ring buffer instance configuration
 171  * @ctx: reservation context
 172  * @event_id: event ID
 173  */
 174 static __inline__
 175 void lttng_write_event_header(const struct lib_ring_buffer_config *config,
 176                             struct lib_ring_buffer_ctx *ctx,
 177                             uint32_t event_id)
 178 {
 179         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 180         struct lttng_event *event = ctx->priv;
 181
 182         if (unlikely(ctx->rflags))
 183                 goto slow_path;
 184
 185         switch (lttng_chan->header_type) {
 186         case 1: /* compact */
 187         {
 188                 uint32_t id_time = 0;
 189
 190                 bt_bitfield_write(&id_time, uint32_t, 0, 5, event_id);
 191                 bt_bitfield_write(&id_time, uint32_t, 5, 27, 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, lttng_chan, lttng_chan->ctx);
 210         ctx_record(ctx, lttng_chan, event->ctx);
 211         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 212
 213         return;
 214
 215 slow_path:
 216         lttng_write_event_header_slow(config, ctx, event_id);
 217 }
 218
 219 static
 220 void lttng_write_event_header_slow(const struct lib_ring_buffer_config *config,
 221                                  struct lib_ring_buffer_ctx *ctx,
 222                                  uint32_t event_id)
 223 {
 224         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 225         struct lttng_event *event = ctx->priv;
 226
 227         switch (lttng_chan->header_type) {
 228         case 1: /* compact */
 229                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 230                         uint32_t id_time = 0;
 231
 232                         bt_bitfield_write(&id_time, uint32_t, 0, 5, event_id);
 233                         bt_bitfield_write(&id_time, uint32_t, 5, 27, ctx->tsc);
 234                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 235                 } else {
 236                         uint8_t id = 0;
 237                         uint64_t timestamp = ctx->tsc;
 238
 239                         bt_bitfield_write(&id, uint8_t, 0, 5, 31);
 240                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 241                         /* Align extended struct on largest member */
 242                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 243                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 244                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 245                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 246                 }
 247                 break;
 248         case 2: /* large */
 249         {
 250                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTTNG_RFLAG_EXTENDED))) {
 251                         uint32_t timestamp = (uint32_t) ctx->tsc;
 252                         uint16_t id = event_id;
 253
 254                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 255                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint32_t));
 256                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 257                 } else {
 258                         uint16_t id = 65535;
 259                         uint64_t timestamp = ctx->tsc;
 260
 261                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 262                         /* Align extended struct on largest member */
 263                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 264                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 265                         lib_ring_buffer_align_ctx(ctx, lttng_alignof(uint64_t));
 266                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 267                 }
 268                 break;
 269         }
 270         default:
 271                 WARN_ON_ONCE(1);
 272         }
 273         ctx_record(ctx, lttng_chan, lttng_chan->ctx);
 274         ctx_record(ctx, lttng_chan, event->ctx);
 275         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 276 }
 277
 278 static const struct lib_ring_buffer_config client_config;
 279
 280 static u64 client_ring_buffer_clock_read(struct channel *chan)
 281 {
 282         return lib_ring_buffer_clock_read(chan);
 283 }
 284
 285 static
 286 size_t client_record_header_size(const struct lib_ring_buffer_config *config,
 287                                  struct channel *chan, size_t offset,
 288                                  size_t *pre_header_padding,
 289                                  struct lib_ring_buffer_ctx *ctx)
 290 {
 291         return record_header_size(config, chan, offset,
 292                                   pre_header_padding, ctx);
 293 }
 294
 295 /**
 296  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 297  *
 298  * Return header size without padding after the structure. Don't use packed
 299  * structure because gcc generates inefficient code on some architectures
 300  * (powerpc, mips..)
 301  */
 302 static size_t client_packet_header_size(void)
 303 {
 304         return offsetof(struct packet_header, ctx.header_end);
 305 }
 306
 307 static void client_buffer_begin(struct lib_ring_buffer *buf, u64 tsc,
 308                                 unsigned int subbuf_idx)
 309 {
 310         struct channel *chan = buf->backend.chan;
 311         struct packet_header *header =
 312                 (struct packet_header *)
 313                         lib_ring_buffer_offset_address(&buf->backend,
 314                                 subbuf_idx * chan->backend.subbuf_size);
 315         struct lttng_channel *lttng_chan = channel_get_private(chan);
 316         struct lttng_session *session = lttng_chan->session;
 317
 318         header->magic = CTF_MAGIC_NUMBER;
 319         memcpy(header->uuid, session->uuid.b, sizeof(session->uuid));
 320         header->stream_id = lttng_chan->id;
 321         header->ctx.timestamp_begin = tsc;
 322         header->ctx.timestamp_end = 0;
 323         header->ctx.events_discarded = 0;
 324         header->ctx.content_size = 0xFFFFFFFF; /* for debugging */
 325         header->ctx.packet_size = 0xFFFFFFFF;
 326         header->ctx.cpu_id = buf->backend.cpu;
 327 }
 328
 329 /*
 330  * offset is assumed to never be 0 here : never deliver a completely empty
 331  * subbuffer. data_size is between 1 and subbuf_size.
 332  */
 333 static void client_buffer_end(struct lib_ring_buffer *buf, u64 tsc,
 334                               unsigned int subbuf_idx, unsigned long data_size)
 335 {
 336         struct channel *chan = buf->backend.chan;
 337         struct packet_header *header =
 338                 (struct packet_header *)
 339                         lib_ring_buffer_offset_address(&buf->backend,
 340                                 subbuf_idx * chan->backend.subbuf_size);
 341         unsigned long records_lost = 0;
 342
 343         header->ctx.timestamp_end = tsc;
 344         header->ctx.content_size = data_size * CHAR_BIT;        /* in bits */
 345         header->ctx.packet_size = PAGE_ALIGN(data_size) * CHAR_BIT; /* in bits */
 346         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
 347         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 348         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 349         header->ctx.events_discarded = records_lost;
 350 }
 351
 352 static int client_buffer_create(struct lib_ring_buffer *buf, void *priv,
 353                                 int cpu, const char *name)
 354 {
 355         return 0;
 356 }
 357
 358 static void client_buffer_finalize(struct lib_ring_buffer *buf, void *priv, int cpu)
 359 {
 360 }
 361
 362 static const struct lib_ring_buffer_config client_config = {
 363         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 364         .cb.record_header_size = client_record_header_size,
 365         .cb.subbuffer_header_size = client_packet_header_size,
 366         .cb.buffer_begin = client_buffer_begin,
 367         .cb.buffer_end = client_buffer_end,
 368         .cb.buffer_create = client_buffer_create,
 369         .cb.buffer_finalize = client_buffer_finalize,
 370
 371         .tsc_bits = 32,
 372         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 373         .sync = RING_BUFFER_SYNC_PER_CPU,
 374         .mode = RING_BUFFER_MODE_TEMPLATE,
 375         .backend = RING_BUFFER_PAGE,
 376         .output = RING_BUFFER_OUTPUT_TEMPLATE,
 377         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 378         .ipi = RING_BUFFER_IPI_BARRIER,
 379         .wakeup = RING_BUFFER_WAKEUP_BY_TIMER,
 380 };
 381
 382 static
 383 struct channel *_channel_create(const char *name,
 384                                 struct lttng_channel *lttng_chan, 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 {
 389         return channel_create(&client_config, name, lttng_chan, buf_addr,
 390                               subbuf_size, num_subbuf, switch_timer_interval,
 391                               read_timer_interval);
 392 }
 393
 394 static
 395 void lttng_channel_destroy(struct channel *chan)
 396 {
 397         channel_destroy(chan);
 398 }
 399
 400 static
 401 struct lib_ring_buffer *lttng_buffer_read_open(struct channel *chan)
 402 {
 403         struct lib_ring_buffer *buf;
 404         int cpu;
 405
 406         for_each_channel_cpu(cpu, chan) {
 407                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 408                 if (!lib_ring_buffer_open_read(buf))
 409                         return buf;
 410         }
 411         return NULL;
 412 }
 413
 414 static
 415 int lttng_buffer_has_read_closed_stream(struct channel *chan)
 416 {
 417         struct lib_ring_buffer *buf;
 418         int cpu;
 419
 420         for_each_channel_cpu(cpu, chan) {
 421                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 422                 if (!atomic_long_read(&buf->active_readers))
 423                         return 1;
 424         }
 425         return 0;
 426 }
 427
 428 static
 429 void lttng_buffer_read_close(struct lib_ring_buffer *buf)
 430 {
 431         lib_ring_buffer_release_read(buf);
 432 }
 433
 434 static
 435 int lttng_event_reserve(struct lib_ring_buffer_ctx *ctx,
 436                       uint32_t event_id)
 437 {
 438         struct lttng_channel *lttng_chan = channel_get_private(ctx->chan);
 439         int ret, cpu;
 440
 441         cpu = lib_ring_buffer_get_cpu(&client_config);
 442         if (cpu < 0)
 443                 return -EPERM;
 444         ctx->cpu = cpu;
 445
 446         switch (lttng_chan->header_type) {
 447         case 1: /* compact */
 448                 if (event_id > 30)
 449                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 450                 break;
 451         case 2: /* large */
 452                 if (event_id > 65534)
 453                         ctx->rflags |= LTTNG_RFLAG_EXTENDED;
 454                 break;
 455         default:
 456                 WARN_ON_ONCE(1);
 457         }
 458
 459         ret = lib_ring_buffer_reserve(&client_config, ctx);
 460         if (ret)
 461                 goto put;
 462         lttng_write_event_header(&client_config, ctx, event_id);
 463         return 0;
 464 put:
 465         lib_ring_buffer_put_cpu(&client_config);
 466         return ret;
 467 }
 468
 469 static
 470 void lttng_event_commit(struct lib_ring_buffer_ctx *ctx)
 471 {
 472         lib_ring_buffer_commit(&client_config, ctx);
 473         lib_ring_buffer_put_cpu(&client_config);
 474 }
 475
 476 static
 477 void lttng_event_write(struct lib_ring_buffer_ctx *ctx, const void *src,
 478                      size_t len)
 479 {
 480         lib_ring_buffer_write(&client_config, ctx, src, len);
 481 }
 482
 483 static
 484 void lttng_event_write_from_user(struct lib_ring_buffer_ctx *ctx,
 485                                const void __user *src, size_t len)
 486 {
 487         lib_ring_buffer_copy_from_user(&client_config, ctx, src, len);
 488 }
 489
 490 static
 491 void lttng_event_memset(struct lib_ring_buffer_ctx *ctx,
 492                 int c, size_t len)
 493 {
 494         lib_ring_buffer_memset(&client_config, ctx, c, len);
 495 }
 496
 497 static
 498 wait_queue_head_t *lttng_get_writer_buf_wait_queue(struct channel *chan, int cpu)
 499 {
 500         struct lib_ring_buffer *buf = channel_get_ring_buffer(&client_config,
 501                                         chan, cpu);
 502         return &buf->write_wait;
 503 }
 504
 505 static
 506 wait_queue_head_t *lttng_get_hp_wait_queue(struct channel *chan)
 507 {
 508         return &chan->hp_wait;
 509 }
 510
 511 static
 512 int lttng_is_finalized(struct channel *chan)
 513 {
 514         return lib_ring_buffer_channel_is_finalized(chan);
 515 }
 516
 517 static
 518 int lttng_is_disabled(struct channel *chan)
 519 {
 520         return lib_ring_buffer_channel_is_disabled(chan);
 521 }
 522
 523 static struct lttng_transport lttng_relay_transport = {
 524         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
 525         .owner = THIS_MODULE,
 526         .ops = {
 527                 .channel_create = _channel_create,
 528                 .channel_destroy = lttng_channel_destroy,
 529                 .buffer_read_open = lttng_buffer_read_open,
 530                 .buffer_has_read_closed_stream =
 531                         lttng_buffer_has_read_closed_stream,
 532                 .buffer_read_close = lttng_buffer_read_close,
 533                 .event_reserve = lttng_event_reserve,
 534                 .event_commit = lttng_event_commit,
 535                 .event_write = lttng_event_write,
 536                 .event_write_from_user = lttng_event_write_from_user,
 537                 .event_memset = lttng_event_memset,
 538                 .packet_avail_size = NULL,      /* Would be racy anyway */
 539                 .get_writer_buf_wait_queue = lttng_get_writer_buf_wait_queue,
 540                 .get_hp_wait_queue = lttng_get_hp_wait_queue,
 541                 .is_finalized = lttng_is_finalized,
 542                 .is_disabled = lttng_is_disabled,
 543         },
 544 };
 545
 546 static int __init lttng_ring_buffer_client_init(void)
 547 {
 548         /*
 549          * This vmalloc sync all also takes care of the lib ring buffer
 550          * vmalloc'd module pages when it is built as a module into LTTng.
 551          */
 552         wrapper_vmalloc_sync_all();
 553         lttng_transport_register(&lttng_relay_transport);
 554         return 0;
 555 }
 556
 557 module_init(lttng_ring_buffer_client_init);
 558
 559 static void __exit lttng_ring_buffer_client_exit(void)
 560 {
 561         lttng_transport_unregister(&lttng_relay_transport);
 562 }
 563
 564 module_exit(lttng_ring_buffer_client_exit);
 565
 566 MODULE_LICENSE("GPL and additional rights");
 567 MODULE_AUTHOR("Mathieu Desnoyers");
 568 MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING
 569                    " client");