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
  27 struct packet_header {
  28         /* Trace packet header */
  29         uint32_t magic;                 /*
  30                                          * Trace magic number.
  31                                          * contains endianness information.
  32                                          */
  33         uint8_t uuid[16];
  34         uint32_t stream_id;
  35
  36         struct {
  37                 /* Stream packet context */
  38                 uint64_t timestamp_begin;       /* Cycle count at subbuffer start */
  39                 uint64_t timestamp_end;         /* Cycle count at subbuffer end */
  40                 uint32_t events_discarded;      /*
  41                                                  * Events lost in this subbuffer since
  42                                                  * the beginning of the trace.
  43                                                  * (may overflow)
  44                                                  */
  45                 uint32_t content_size;          /* Size of data in subbuffer */
  46                 uint32_t packet_size;           /* Subbuffer size (include padding) */
  47                 uint32_t cpu_id;                /* CPU id associated with stream */
  48                 uint8_t header_end;             /* End of header */
  49         } ctx;
  50 };
  51
  52
  53 static inline notrace u64 lib_ring_buffer_clock_read(struct channel *chan)
  54 {
  55         return trace_clock_read64();
  56 }
  57
  58 static inline
  59 size_t ctx_get_size(size_t offset, struct lttng_ctx *ctx)
  60 {
  61         int i;
  62         size_t orig_offset = offset;
  63
  64         if (likely(!ctx))
  65                 return 0;
  66         for (i = 0; i < ctx->nr_fields; i++)
  67                 offset += ctx->fields[i].get_size(offset);
  68         return offset - orig_offset;
  69 }
  70
  71 static inline
  72 void ctx_record(struct lib_ring_buffer_ctx *bufctx,
  73                 struct ltt_channel *chan,
  74                 struct lttng_ctx *ctx)
  75 {
  76         int i;
  77
  78         if (likely(!ctx))
  79                 return;
  80         for (i = 0; i < ctx->nr_fields; i++)
  81                 ctx->fields[i].record(&ctx->fields[i], bufctx, chan);
  82 }
  83
  84 /*
  85  * record_header_size - Calculate the header size and padding necessary.
  86  * @config: ring buffer instance configuration
  87  * @chan: channel
  88  * @offset: offset in the write buffer
  89  * @pre_header_padding: padding to add before the header (output)
  90  * @ctx: reservation context
  91  *
  92  * Returns the event header size (including padding).
  93  *
  94  * The payload must itself determine its own alignment from the biggest type it
  95  * contains.
  96  */
  97 static __inline__
  98 unsigned char record_header_size(const struct lib_ring_buffer_config *config,
  99                                  struct channel *chan, size_t offset,
 100                                  size_t *pre_header_padding,
 101                                  struct lib_ring_buffer_ctx *ctx)
 102 {
 103         struct ltt_channel *ltt_chan = channel_get_private(chan);
 104         struct ltt_event *event = ctx->priv;
 105         size_t orig_offset = offset;
 106         size_t padding;
 107
 108         switch (ltt_chan->header_type) {
 109         case 1: /* compact */
 110                 padding = lib_ring_buffer_align(offset, ltt_alignof(uint32_t));
 111                 offset += padding;
 112                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 113                         offset += sizeof(uint32_t);     /* id and timestamp */
 114                 } else {
 115                         /* Minimum space taken by 5-bit id */
 116                         offset += sizeof(uint8_t);
 117                         /* Align extended struct on largest member */
 118                         offset += lib_ring_buffer_align(offset, ltt_alignof(uint64_t));
 119                         offset += sizeof(uint32_t);     /* id */
 120                         offset += lib_ring_buffer_align(offset, ltt_alignof(uint64_t));
 121                         offset += sizeof(uint64_t);     /* timestamp */
 122                 }
 123                 break;
 124         case 2: /* large */
 125                 padding = lib_ring_buffer_align(offset, ltt_alignof(uint16_t));
 126                 offset += padding;
 127                 offset += sizeof(uint16_t);
 128                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 129                         offset += lib_ring_buffer_align(offset, ltt_alignof(uint32_t));
 130                         offset += sizeof(uint32_t);     /* timestamp */
 131                 } else {
 132                         /* Align extended struct on largest member */
 133                         offset += lib_ring_buffer_align(offset, ltt_alignof(uint64_t));
 134                         offset += sizeof(uint32_t);     /* id */
 135                         offset += lib_ring_buffer_align(offset, ltt_alignof(uint64_t));
 136                         offset += sizeof(uint64_t);     /* timestamp */
 137                 }
 138                 break;
 139         default:
 140                 padding = 0;
 141                 WARN_ON_ONCE(1);
 142         }
 143         offset += ctx_get_size(offset, event->ctx);
 144         offset += ctx_get_size(offset, ltt_chan->ctx);
 145
 146         *pre_header_padding = padding;
 147         return offset - orig_offset;
 148 }
 149
 150 #include "wrapper/ringbuffer/api.h"
 151
 152 static
 153 void ltt_write_event_header_slow(const struct lib_ring_buffer_config *config,
 154                                  struct lib_ring_buffer_ctx *ctx,
 155                                  uint32_t event_id);
 156
 157 /*
 158  * ltt_write_event_header
 159  *
 160  * Writes the event header to the offset (already aligned on 32-bits).
 161  *
 162  * @config: ring buffer instance configuration
 163  * @ctx: reservation context
 164  * @event_id: event ID
 165  */
 166 static __inline__
 167 void ltt_write_event_header(const struct lib_ring_buffer_config *config,
 168                             struct lib_ring_buffer_ctx *ctx,
 169                             uint32_t event_id)
 170 {
 171         struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 172         struct ltt_event *event = ctx->priv;
 173
 174         if (unlikely(ctx->rflags))
 175                 goto slow_path;
 176
 177         switch (ltt_chan->header_type) {
 178         case 1: /* compact */
 179         {
 180                 uint32_t id_time = 0;
 181
 182                 bt_bitfield_write(&id_time, uint32_t, 0, 5, event_id);
 183                 bt_bitfield_write(&id_time, uint32_t, 5, 27, ctx->tsc);
 184                 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 185                 break;
 186         }
 187         case 2: /* large */
 188         {
 189                 uint32_t timestamp = (uint32_t) ctx->tsc;
 190                 uint16_t id = event_id;
 191
 192                 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 193                 lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint32_t));
 194                 lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 195                 break;
 196         }
 197         default:
 198                 WARN_ON_ONCE(1);
 199         }
 200
 201         ctx_record(ctx, ltt_chan, event->ctx);
 202         ctx_record(ctx, ltt_chan, ltt_chan->ctx);
 203
 204         return;
 205
 206 slow_path:
 207         ltt_write_event_header_slow(config, ctx, event_id);
 208 }
 209
 210 static
 211 void ltt_write_event_header_slow(const struct lib_ring_buffer_config *config,
 212                                  struct lib_ring_buffer_ctx *ctx,
 213                                  uint32_t event_id)
 214 {
 215         struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 216         struct ltt_event *event = ctx->priv;
 217
 218         switch (ltt_chan->header_type) {
 219         case 1: /* compact */
 220                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 221                         uint32_t id_time = 0;
 222
 223                         bt_bitfield_write(&id_time, uint32_t, 0, 5, event_id);
 224                         bt_bitfield_write(&id_time, uint32_t, 5, 27, ctx->tsc);
 225                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 226                 } else {
 227                         uint8_t id = 0;
 228                         uint64_t timestamp = ctx->tsc;
 229
 230                         bt_bitfield_write(&id, uint8_t, 0, 5, 31);
 231                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 232                         /* Align extended struct on largest member */
 233                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
 234                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 235                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
 236                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 237                 }
 238                 break;
 239         case 2: /* large */
 240         {
 241                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 242                         uint32_t timestamp = (uint32_t) ctx->tsc;
 243                         uint16_t id = event_id;
 244
 245                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 246                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint32_t));
 247                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 248                 } else {
 249                         uint16_t id = 65535;
 250                         uint64_t timestamp = ctx->tsc;
 251
 252                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 253                         /* Align extended struct on largest member */
 254                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
 255                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 256                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
 257                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 258                 }
 259                 break;
 260         }
 261         default:
 262                 WARN_ON_ONCE(1);
 263         }
 264         ctx_record(ctx, ltt_chan, event->ctx);
 265         ctx_record(ctx, ltt_chan, ltt_chan->ctx);
 266 }
 267
 268 static const struct lib_ring_buffer_config client_config;
 269
 270 static u64 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 lib_ring_buffer_config *config,
 277                                  struct channel *chan, size_t offset,
 278                                  size_t *pre_header_padding,
 279                                  struct 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 lib_ring_buffer *buf, u64 tsc,
 298                                 unsigned int subbuf_idx)
 299 {
 300         struct channel *chan = buf->backend.chan;
 301         struct packet_header *header =
 302                 (struct packet_header *)
 303                         lib_ring_buffer_offset_address(&buf->backend,
 304                                 subbuf_idx * chan->backend.subbuf_size);
 305         struct ltt_channel *ltt_chan = channel_get_private(chan);
 306         struct ltt_session *session = ltt_chan->session;
 307
 308         header->magic = CTF_MAGIC_NUMBER;
 309         memcpy(header->uuid, session->uuid.b, sizeof(session->uuid));
 310         header->stream_id = ltt_chan->id;
 311         header->ctx.timestamp_begin = tsc;
 312         header->ctx.timestamp_end = 0;
 313         header->ctx.events_discarded = 0;
 314         header->ctx.content_size = 0xFFFFFFFF; /* for debugging */
 315         header->ctx.packet_size = 0xFFFFFFFF;
 316         header->ctx.cpu_id = buf->backend.cpu;
 317 }
 318
 319 /*
 320  * offset is assumed to never be 0 here : never deliver a completely empty
 321  * subbuffer. data_size is between 1 and subbuf_size.
 322  */
 323 static void client_buffer_end(struct lib_ring_buffer *buf, u64 tsc,
 324                               unsigned int subbuf_idx, unsigned long data_size)
 325 {
 326         struct channel *chan = buf->backend.chan;
 327         struct packet_header *header =
 328                 (struct packet_header *)
 329                         lib_ring_buffer_offset_address(&buf->backend,
 330                                 subbuf_idx * chan->backend.subbuf_size);
 331         unsigned long records_lost = 0;
 332
 333         header->ctx.timestamp_end = tsc;
 334         header->ctx.content_size = data_size * CHAR_BIT;        /* in bits */
 335         header->ctx.packet_size = PAGE_ALIGN(data_size) * CHAR_BIT; /* in bits */
 336         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
 337         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 338         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 339         header->ctx.events_discarded = records_lost;
 340 }
 341
 342 static int client_buffer_create(struct lib_ring_buffer *buf, void *priv,
 343                                 int cpu, const char *name)
 344 {
 345         return 0;
 346 }
 347
 348 static void client_buffer_finalize(struct lib_ring_buffer *buf, void *priv, int cpu)
 349 {
 350 }
 351
 352 static const struct lib_ring_buffer_config client_config = {
 353         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 354         .cb.record_header_size = client_record_header_size,
 355         .cb.subbuffer_header_size = client_packet_header_size,
 356         .cb.buffer_begin = client_buffer_begin,
 357         .cb.buffer_end = client_buffer_end,
 358         .cb.buffer_create = client_buffer_create,
 359         .cb.buffer_finalize = client_buffer_finalize,
 360
 361         .tsc_bits = 32,
 362         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 363         .sync = RING_BUFFER_SYNC_PER_CPU,
 364         .mode = RING_BUFFER_MODE_TEMPLATE,
 365         .backend = RING_BUFFER_PAGE,
 366         .output = RING_BUFFER_OUTPUT_TEMPLATE,
 367         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 368         .ipi = RING_BUFFER_IPI_BARRIER,
 369         .wakeup = RING_BUFFER_WAKEUP_BY_TIMER,
 370 };
 371
 372 static
 373 struct channel *_channel_create(const char *name,
 374                                 struct ltt_channel *ltt_chan, void *buf_addr,
 375                                 size_t subbuf_size, size_t num_subbuf,
 376                                 unsigned int switch_timer_interval,
 377                                 unsigned int read_timer_interval)
 378 {
 379         return channel_create(&client_config, name, ltt_chan, buf_addr,
 380                               subbuf_size, num_subbuf, switch_timer_interval,
 381                               read_timer_interval);
 382 }
 383
 384 static
 385 void ltt_channel_destroy(struct channel *chan)
 386 {
 387         channel_destroy(chan);
 388 }
 389
 390 static
 391 struct lib_ring_buffer *ltt_buffer_read_open(struct channel *chan)
 392 {
 393         struct lib_ring_buffer *buf;
 394         int cpu;
 395
 396         for_each_channel_cpu(cpu, chan) {
 397                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 398                 if (!lib_ring_buffer_open_read(buf))
 399                         return buf;
 400         }
 401         return NULL;
 402 }
 403
 404 static
 405 int ltt_buffer_has_read_closed_stream(struct channel *chan)
 406 {
 407         struct lib_ring_buffer *buf;
 408         int cpu;
 409
 410         for_each_channel_cpu(cpu, chan) {
 411                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 412                 if (!atomic_long_read(&buf->active_readers))
 413                         return 1;
 414         }
 415         return 0;
 416 }
 417
 418 static
 419 void ltt_buffer_read_close(struct lib_ring_buffer *buf)
 420 {
 421         lib_ring_buffer_release_read(buf);
 422 }
 423
 424 static
 425 int ltt_event_reserve(struct lib_ring_buffer_ctx *ctx,
 426                       uint32_t event_id)
 427 {
 428         struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 429         int ret, cpu;
 430
 431         cpu = lib_ring_buffer_get_cpu(&client_config);
 432         if (cpu < 0)
 433                 return -EPERM;
 434         ctx->cpu = cpu;
 435
 436         switch (ltt_chan->header_type) {
 437         case 1: /* compact */
 438                 if (event_id > 30)
 439                         ctx->rflags |= LTT_RFLAG_EXTENDED;
 440                 break;
 441         case 2: /* large */
 442                 if (event_id > 65534)
 443                         ctx->rflags |= LTT_RFLAG_EXTENDED;
 444                 break;
 445         default:
 446                 WARN_ON_ONCE(1);
 447         }
 448
 449         ret = lib_ring_buffer_reserve(&client_config, ctx);
 450         if (ret)
 451                 goto put;
 452         ltt_write_event_header(&client_config, ctx, event_id);
 453         return 0;
 454 put:
 455         lib_ring_buffer_put_cpu(&client_config);
 456         return ret;
 457 }
 458
 459 static
 460 void ltt_event_commit(struct lib_ring_buffer_ctx *ctx)
 461 {
 462         lib_ring_buffer_commit(&client_config, ctx);
 463         lib_ring_buffer_put_cpu(&client_config);
 464 }
 465
 466 static
 467 void ltt_event_write(struct lib_ring_buffer_ctx *ctx, const void *src,
 468                      size_t len)
 469 {
 470         lib_ring_buffer_write(&client_config, ctx, src, len);
 471 }
 472
 473 static
 474 wait_queue_head_t *ltt_get_reader_wait_queue(struct channel *chan)
 475 {
 476         return &chan->read_wait;
 477 }
 478
 479 static
 480 wait_queue_head_t *ltt_get_hp_wait_queue(struct channel *chan)
 481 {
 482         return &chan->hp_wait;
 483 }
 484
 485 static
 486 int ltt_is_finalized(struct channel *chan)
 487 {
 488         return lib_ring_buffer_channel_is_finalized(chan);
 489 }
 490
 491 static
 492 int ltt_is_disabled(struct channel *chan)
 493 {
 494         return lib_ring_buffer_channel_is_disabled(chan);
 495 }
 496
 497 static struct ltt_transport ltt_relay_transport = {
 498         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
 499         .owner = THIS_MODULE,
 500         .ops = {
 501                 .channel_create = _channel_create,
 502                 .channel_destroy = ltt_channel_destroy,
 503                 .buffer_read_open = ltt_buffer_read_open,
 504                 .buffer_has_read_closed_stream =
 505                         ltt_buffer_has_read_closed_stream,
 506                 .buffer_read_close = ltt_buffer_read_close,
 507                 .event_reserve = ltt_event_reserve,
 508                 .event_commit = ltt_event_commit,
 509                 .event_write = ltt_event_write,
 510                 .packet_avail_size = NULL,      /* Would be racy anyway */
 511                 .get_reader_wait_queue = ltt_get_reader_wait_queue,
 512                 .get_hp_wait_queue = ltt_get_hp_wait_queue,
 513                 .is_finalized = ltt_is_finalized,
 514                 .is_disabled = ltt_is_disabled,
 515         },
 516 };
 517
 518 static int __init ltt_ring_buffer_client_init(void)
 519 {
 520         /*
 521          * This vmalloc sync all also takes care of the lib ring buffer
 522          * vmalloc'd module pages when it is built as a module into LTTng.
 523          */
 524         wrapper_vmalloc_sync_all();
 525         ltt_transport_register(&ltt_relay_transport);
 526         return 0;
 527 }
 528
 529 module_init(ltt_ring_buffer_client_init);
 530
 531 static void __exit ltt_ring_buffer_client_exit(void)
 532 {
 533         ltt_transport_unregister(&ltt_relay_transport);
 534 }
 535
 536 module_exit(ltt_ring_buffer_client_exit);
 537
 538 MODULE_LICENSE("GPL and additional rights");
 539 MODULE_AUTHOR("Mathieu Desnoyers");
 540 MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING
 541                    " client");