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 <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 "ltt-events.h"
  17 #include "ltt-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 ltt_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 ltt_channel *ltt_chan = channel_get_private(chan);
 112         struct ltt_event *event = ctx->priv;
 113         size_t orig_offset = offset;
 114         size_t padding;
 115
 116         switch (ltt_chan->header_type) {
 117         case 1: /* compact */
 118                 padding = lib_ring_buffer_align(offset, ltt_alignof(uint32_t));
 119                 offset += padding;
 120                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_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, ltt_alignof(uint64_t));
 127                         offset += sizeof(uint32_t);     /* id */
 128                         offset += lib_ring_buffer_align(offset, ltt_alignof(uint64_t));
 129                         offset += sizeof(uint64_t);     /* timestamp */
 130                 }
 131                 break;
 132         case 2: /* large */
 133                 padding = lib_ring_buffer_align(offset, ltt_alignof(uint16_t));
 134                 offset += padding;
 135                 offset += sizeof(uint16_t);
 136                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 137                         offset += lib_ring_buffer_align(offset, ltt_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, ltt_alignof(uint64_t));
 142                         offset += sizeof(uint32_t);     /* id */
 143                         offset += lib_ring_buffer_align(offset, ltt_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, ltt_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 ltt_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  * ltt_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 ltt_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 ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 180         struct ltt_event *event = ctx->priv;
 181
 182         if (unlikely(ctx->rflags))
 183                 goto slow_path;
 184
 185         switch (ltt_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, ltt_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
 212         return;
 213
 214 slow_path:
 215         ltt_write_event_header_slow(config, ctx, event_id);
 216 }
 217
 218 static
 219 void ltt_write_event_header_slow(const struct lib_ring_buffer_config *config,
 220                                  struct lib_ring_buffer_ctx *ctx,
 221                                  uint32_t event_id)
 222 {
 223         struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 224         struct ltt_event *event = ctx->priv;
 225
 226         switch (ltt_chan->header_type) {
 227         case 1: /* compact */
 228                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 229                         uint32_t id_time = 0;
 230
 231                         bt_bitfield_write(&id_time, uint32_t, 0, 5, event_id);
 232                         bt_bitfield_write(&id_time, uint32_t, 5, 27, ctx->tsc);
 233                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 234                 } else {
 235                         uint8_t id = 0;
 236                         uint64_t timestamp = ctx->tsc;
 237
 238                         bt_bitfield_write(&id, uint8_t, 0, 5, 31);
 239                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 240                         /* Align extended struct on largest member */
 241                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
 242                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 243                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
 244                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 245                 }
 246                 break;
 247         case 2: /* large */
 248         {
 249                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 250                         uint32_t timestamp = (uint32_t) ctx->tsc;
 251                         uint16_t id = event_id;
 252
 253                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 254                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint32_t));
 255                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 256                 } else {
 257                         uint16_t id = 65535;
 258                         uint64_t timestamp = ctx->tsc;
 259
 260                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 261                         /* Align extended struct on largest member */
 262                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
 263                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 264                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
 265                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 266                 }
 267                 break;
 268         }
 269         default:
 270                 WARN_ON_ONCE(1);
 271         }
 272         ctx_record(ctx, ltt_chan, ltt_chan->ctx);
 273         ctx_record(ctx, ltt_chan, event->ctx);
 274 }
 275
 276 static const struct lib_ring_buffer_config client_config;
 277
 278 static u64 client_ring_buffer_clock_read(struct channel *chan)
 279 {
 280         return lib_ring_buffer_clock_read(chan);
 281 }
 282
 283 static
 284 size_t client_record_header_size(const struct lib_ring_buffer_config *config,
 285                                  struct channel *chan, size_t offset,
 286                                  size_t *pre_header_padding,
 287                                  struct lib_ring_buffer_ctx *ctx)
 288 {
 289         return record_header_size(config, chan, offset,
 290                                   pre_header_padding, ctx);
 291 }
 292
 293 /**
 294  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 295  *
 296  * Return header size without padding after the structure. Don't use packed
 297  * structure because gcc generates inefficient code on some architectures
 298  * (powerpc, mips..)
 299  */
 300 static size_t client_packet_header_size(void)
 301 {
 302         return offsetof(struct packet_header, ctx.header_end);
 303 }
 304
 305 static void client_buffer_begin(struct lib_ring_buffer *buf, u64 tsc,
 306                                 unsigned int subbuf_idx)
 307 {
 308         struct channel *chan = buf->backend.chan;
 309         struct packet_header *header =
 310                 (struct packet_header *)
 311                         lib_ring_buffer_offset_address(&buf->backend,
 312                                 subbuf_idx * chan->backend.subbuf_size);
 313         struct ltt_channel *ltt_chan = channel_get_private(chan);
 314         struct ltt_session *session = ltt_chan->session;
 315
 316         header->magic = CTF_MAGIC_NUMBER;
 317         memcpy(header->uuid, session->uuid.b, sizeof(session->uuid));
 318         header->stream_id = ltt_chan->id;
 319         header->ctx.timestamp_begin = tsc;
 320         header->ctx.timestamp_end = 0;
 321         header->ctx.events_discarded = 0;
 322         header->ctx.content_size = 0xFFFFFFFF; /* for debugging */
 323         header->ctx.packet_size = 0xFFFFFFFF;
 324         header->ctx.cpu_id = buf->backend.cpu;
 325 }
 326
 327 /*
 328  * offset is assumed to never be 0 here : never deliver a completely empty
 329  * subbuffer. data_size is between 1 and subbuf_size.
 330  */
 331 static void client_buffer_end(struct lib_ring_buffer *buf, u64 tsc,
 332                               unsigned int subbuf_idx, unsigned long data_size)
 333 {
 334         struct channel *chan = buf->backend.chan;
 335         struct packet_header *header =
 336                 (struct packet_header *)
 337                         lib_ring_buffer_offset_address(&buf->backend,
 338                                 subbuf_idx * chan->backend.subbuf_size);
 339         unsigned long records_lost = 0;
 340
 341         header->ctx.timestamp_end = tsc;
 342         header->ctx.content_size = data_size * CHAR_BIT;        /* in bits */
 343         header->ctx.packet_size = PAGE_ALIGN(data_size) * CHAR_BIT; /* in bits */
 344         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
 345         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 346         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 347         header->ctx.events_discarded = records_lost;
 348 }
 349
 350 static int client_buffer_create(struct lib_ring_buffer *buf, void *priv,
 351                                 int cpu, const char *name)
 352 {
 353         return 0;
 354 }
 355
 356 static void client_buffer_finalize(struct lib_ring_buffer *buf, void *priv, int cpu)
 357 {
 358 }
 359
 360 static const struct lib_ring_buffer_config client_config = {
 361         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 362         .cb.record_header_size = client_record_header_size,
 363         .cb.subbuffer_header_size = client_packet_header_size,
 364         .cb.buffer_begin = client_buffer_begin,
 365         .cb.buffer_end = client_buffer_end,
 366         .cb.buffer_create = client_buffer_create,
 367         .cb.buffer_finalize = client_buffer_finalize,
 368
 369         .tsc_bits = 32,
 370         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 371         .sync = RING_BUFFER_SYNC_PER_CPU,
 372         .mode = RING_BUFFER_MODE_TEMPLATE,
 373         .backend = RING_BUFFER_PAGE,
 374         .output = RING_BUFFER_OUTPUT_TEMPLATE,
 375         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 376         .ipi = RING_BUFFER_IPI_BARRIER,
 377         .wakeup = RING_BUFFER_WAKEUP_BY_TIMER,
 378 };
 379
 380 static
 381 struct channel *_channel_create(const char *name,
 382                                 struct ltt_channel *ltt_chan, void *buf_addr,
 383                                 size_t subbuf_size, size_t num_subbuf,
 384                                 unsigned int switch_timer_interval,
 385                                 unsigned int read_timer_interval)
 386 {
 387         return channel_create(&client_config, name, ltt_chan, buf_addr,
 388                               subbuf_size, num_subbuf, switch_timer_interval,
 389                               read_timer_interval);
 390 }
 391
 392 static
 393 void ltt_channel_destroy(struct channel *chan)
 394 {
 395         channel_destroy(chan);
 396 }
 397
 398 static
 399 struct lib_ring_buffer *ltt_buffer_read_open(struct channel *chan)
 400 {
 401         struct lib_ring_buffer *buf;
 402         int cpu;
 403
 404         for_each_channel_cpu(cpu, chan) {
 405                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 406                 if (!lib_ring_buffer_open_read(buf))
 407                         return buf;
 408         }
 409         return NULL;
 410 }
 411
 412 static
 413 int ltt_buffer_has_read_closed_stream(struct channel *chan)
 414 {
 415         struct lib_ring_buffer *buf;
 416         int cpu;
 417
 418         for_each_channel_cpu(cpu, chan) {
 419                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 420                 if (!atomic_long_read(&buf->active_readers))
 421                         return 1;
 422         }
 423         return 0;
 424 }
 425
 426 static
 427 void ltt_buffer_read_close(struct lib_ring_buffer *buf)
 428 {
 429         lib_ring_buffer_release_read(buf);
 430 }
 431
 432 static
 433 int ltt_event_reserve(struct lib_ring_buffer_ctx *ctx,
 434                       uint32_t event_id)
 435 {
 436         struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 437         int ret, cpu;
 438
 439         cpu = lib_ring_buffer_get_cpu(&client_config);
 440         if (cpu < 0)
 441                 return -EPERM;
 442         ctx->cpu = cpu;
 443
 444         switch (ltt_chan->header_type) {
 445         case 1: /* compact */
 446                 if (event_id > 30)
 447                         ctx->rflags |= LTT_RFLAG_EXTENDED;
 448                 break;
 449         case 2: /* large */
 450                 if (event_id > 65534)
 451                         ctx->rflags |= LTT_RFLAG_EXTENDED;
 452                 break;
 453         default:
 454                 WARN_ON_ONCE(1);
 455         }
 456
 457         ret = lib_ring_buffer_reserve(&client_config, ctx);
 458         if (ret)
 459                 goto put;
 460         ltt_write_event_header(&client_config, ctx, event_id);
 461         return 0;
 462 put:
 463         lib_ring_buffer_put_cpu(&client_config);
 464         return ret;
 465 }
 466
 467 static
 468 void ltt_event_commit(struct lib_ring_buffer_ctx *ctx)
 469 {
 470         lib_ring_buffer_commit(&client_config, ctx);
 471         lib_ring_buffer_put_cpu(&client_config);
 472 }
 473
 474 static
 475 void ltt_event_write(struct lib_ring_buffer_ctx *ctx, const void *src,
 476                      size_t len)
 477 {
 478         lib_ring_buffer_write(&client_config, ctx, src, len);
 479 }
 480
 481 static
 482 wait_queue_head_t *ltt_get_writer_buf_wait_queue(struct channel *chan, int cpu)
 483 {
 484         struct lib_ring_buffer *buf = channel_get_ring_buffer(&client_config,
 485                                         chan, cpu);
 486         return &buf->write_wait;
 487 }
 488
 489 static
 490 wait_queue_head_t *ltt_get_hp_wait_queue(struct channel *chan)
 491 {
 492         return &chan->hp_wait;
 493 }
 494
 495 static
 496 int ltt_is_finalized(struct channel *chan)
 497 {
 498         return lib_ring_buffer_channel_is_finalized(chan);
 499 }
 500
 501 static
 502 int ltt_is_disabled(struct channel *chan)
 503 {
 504         return lib_ring_buffer_channel_is_disabled(chan);
 505 }
 506
 507 static struct ltt_transport ltt_relay_transport = {
 508         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
 509         .owner = THIS_MODULE,
 510         .ops = {
 511                 .channel_create = _channel_create,
 512                 .channel_destroy = ltt_channel_destroy,
 513                 .buffer_read_open = ltt_buffer_read_open,
 514                 .buffer_has_read_closed_stream =
 515                         ltt_buffer_has_read_closed_stream,
 516                 .buffer_read_close = ltt_buffer_read_close,
 517                 .event_reserve = ltt_event_reserve,
 518                 .event_commit = ltt_event_commit,
 519                 .event_write = ltt_event_write,
 520                 .packet_avail_size = NULL,      /* Would be racy anyway */
 521                 .get_writer_buf_wait_queue = ltt_get_writer_buf_wait_queue,
 522                 .get_hp_wait_queue = ltt_get_hp_wait_queue,
 523                 .is_finalized = ltt_is_finalized,
 524                 .is_disabled = ltt_is_disabled,
 525         },
 526 };
 527
 528 static int __init ltt_ring_buffer_client_init(void)
 529 {
 530         /*
 531          * This vmalloc sync all also takes care of the lib ring buffer
 532          * vmalloc'd module pages when it is built as a module into LTTng.
 533          */
 534         wrapper_vmalloc_sync_all();
 535         ltt_transport_register(&ltt_relay_transport);
 536         return 0;
 537 }
 538
 539 module_init(ltt_ring_buffer_client_init);
 540
 541 static void __exit ltt_ring_buffer_client_exit(void)
 542 {
 543         ltt_transport_unregister(&ltt_relay_transport);
 544 }
 545
 546 module_exit(ltt_ring_buffer_client_exit);
 547
 548 MODULE_LICENSE("GPL and additional rights");
 549 MODULE_AUTHOR("Mathieu Desnoyers");
 550 MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING
 551                    " client");