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                 WARN_ON_ONCE(1);
 141         }
 142         offset += ctx_get_size(offset, event->ctx);
 143         offset += ctx_get_size(offset, ltt_chan->ctx);
 144
 145         *pre_header_padding = padding;
 146         return offset - orig_offset;
 147 }
 148
 149 #include "wrapper/ringbuffer/api.h"
 150
 151 extern
 152 void ltt_write_event_header_slow(const struct lib_ring_buffer_config *config,
 153                                  struct lib_ring_buffer_ctx *ctx,
 154                                  uint32_t event_id);
 155
 156 /*
 157  * ltt_write_event_header
 158  *
 159  * Writes the event header to the offset (already aligned on 32-bits).
 160  *
 161  * @config: ring buffer instance configuration
 162  * @ctx: reservation context
 163  * @event_id: event ID
 164  */
 165 static __inline__
 166 void ltt_write_event_header(const struct lib_ring_buffer_config *config,
 167                             struct lib_ring_buffer_ctx *ctx,
 168                             uint32_t event_id)
 169 {
 170         struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 171         struct ltt_event *event = ctx->priv;
 172
 173         if (unlikely(ctx->rflags))
 174                 goto slow_path;
 175
 176         switch (ltt_chan->header_type) {
 177         case 1: /* compact */
 178         {
 179                 uint32_t id_time = 0;
 180
 181                 bt_bitfield_write(&id_time, uint32_t, 0, 5, event_id);
 182                 bt_bitfield_write(&id_time, uint32_t, 5, 27, ctx->tsc);
 183                 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 184                 break;
 185         }
 186         case 2: /* large */
 187         {
 188                 uint32_t timestamp = (uint32_t) ctx->tsc;
 189                 uint16_t id = event_id;
 190
 191                 lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 192                 lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint32_t));
 193                 lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 194                 break;
 195         }
 196         default:
 197                 WARN_ON_ONCE(1);
 198         }
 199
 200         ctx_record(ctx, ltt_chan, event->ctx);
 201         ctx_record(ctx, ltt_chan, ltt_chan->ctx);
 202
 203         return;
 204
 205 slow_path:
 206         ltt_write_event_header_slow(config, ctx, event_id);
 207 }
 208
 209 void ltt_write_event_header_slow(const struct lib_ring_buffer_config *config,
 210                                  struct lib_ring_buffer_ctx *ctx,
 211                                  uint32_t event_id)
 212 {
 213         struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 214         struct ltt_event *event = ctx->priv;
 215
 216         switch (ltt_chan->header_type) {
 217         case 1: /* compact */
 218                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 219                         uint32_t id_time = 0;
 220
 221                         bt_bitfield_write(&id_time, uint32_t, 0, 5, event_id);
 222                         bt_bitfield_write(&id_time, uint32_t, 5, 27, ctx->tsc);
 223                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 224                 } else {
 225                         uint8_t id = 0;
 226                         uint64_t timestamp = ctx->tsc;
 227
 228                         bt_bitfield_write(&id, uint8_t, 0, 5, 31);
 229                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 230                         /* Align extended struct on largest member */
 231                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
 232                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 233                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
 234                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 235                 }
 236                 break;
 237         case 2: /* large */
 238         {
 239                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 240                         uint32_t timestamp = (uint32_t) ctx->tsc;
 241                         uint16_t id = event_id;
 242
 243                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 244                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint32_t));
 245                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 246                 } else {
 247                         uint16_t id = 65535;
 248                         uint64_t timestamp = ctx->tsc;
 249
 250                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 251                         /* Align extended struct on largest member */
 252                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
 253                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 254                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
 255                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 256                 }
 257                 break;
 258         }
 259         default:
 260                 WARN_ON_ONCE(1);
 261         }
 262         ctx_record(ctx, ltt_chan, event->ctx);
 263         ctx_record(ctx, ltt_chan, ltt_chan->ctx);
 264 }
 265
 266 static const struct lib_ring_buffer_config client_config;
 267
 268 static u64 client_ring_buffer_clock_read(struct channel *chan)
 269 {
 270         return lib_ring_buffer_clock_read(chan);
 271 }
 272
 273 static
 274 size_t client_record_header_size(const struct lib_ring_buffer_config *config,
 275                                  struct channel *chan, size_t offset,
 276                                  size_t *pre_header_padding,
 277                                  struct lib_ring_buffer_ctx *ctx)
 278 {
 279         return record_header_size(config, chan, offset,
 280                                   pre_header_padding, ctx);
 281 }
 282
 283 /**
 284  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 285  *
 286  * Return header size without padding after the structure. Don't use packed
 287  * structure because gcc generates inefficient code on some architectures
 288  * (powerpc, mips..)
 289  */
 290 static size_t client_packet_header_size(void)
 291 {
 292         return offsetof(struct packet_header, ctx.header_end);
 293 }
 294
 295 static void client_buffer_begin(struct lib_ring_buffer *buf, u64 tsc,
 296                                 unsigned int subbuf_idx)
 297 {
 298         struct channel *chan = buf->backend.chan;
 299         struct packet_header *header =
 300                 (struct packet_header *)
 301                         lib_ring_buffer_offset_address(&buf->backend,
 302                                 subbuf_idx * chan->backend.subbuf_size);
 303         struct ltt_channel *ltt_chan = channel_get_private(chan);
 304         struct ltt_session *session = ltt_chan->session;
 305
 306         header->magic = CTF_MAGIC_NUMBER;
 307         memcpy(header->uuid, session->uuid.b, sizeof(session->uuid));
 308         header->stream_id = ltt_chan->id;
 309         header->ctx.timestamp_begin = tsc;
 310         header->ctx.timestamp_end = 0;
 311         header->ctx.events_discarded = 0;
 312         header->ctx.content_size = 0xFFFFFFFF; /* for debugging */
 313         header->ctx.packet_size = 0xFFFFFFFF;
 314         header->ctx.cpu_id = buf->backend.cpu;
 315 }
 316
 317 /*
 318  * offset is assumed to never be 0 here : never deliver a completely empty
 319  * subbuffer. data_size is between 1 and subbuf_size.
 320  */
 321 static void client_buffer_end(struct lib_ring_buffer *buf, u64 tsc,
 322                               unsigned int subbuf_idx, unsigned long data_size)
 323 {
 324         struct channel *chan = buf->backend.chan;
 325         struct packet_header *header =
 326                 (struct packet_header *)
 327                         lib_ring_buffer_offset_address(&buf->backend,
 328                                 subbuf_idx * chan->backend.subbuf_size);
 329         unsigned long records_lost = 0;
 330
 331         header->ctx.timestamp_end = tsc;
 332         header->ctx.content_size = data_size * CHAR_BIT;        /* in bits */
 333         header->ctx.packet_size = PAGE_ALIGN(data_size) * CHAR_BIT; /* in bits */
 334         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
 335         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 336         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 337         header->ctx.events_discarded = records_lost;
 338 }
 339
 340 static int client_buffer_create(struct lib_ring_buffer *buf, void *priv,
 341                                 int cpu, const char *name)
 342 {
 343         return 0;
 344 }
 345
 346 static void client_buffer_finalize(struct lib_ring_buffer *buf, void *priv, int cpu)
 347 {
 348 }
 349
 350 static const struct lib_ring_buffer_config client_config = {
 351         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 352         .cb.record_header_size = client_record_header_size,
 353         .cb.subbuffer_header_size = client_packet_header_size,
 354         .cb.buffer_begin = client_buffer_begin,
 355         .cb.buffer_end = client_buffer_end,
 356         .cb.buffer_create = client_buffer_create,
 357         .cb.buffer_finalize = client_buffer_finalize,
 358
 359         .tsc_bits = 32,
 360         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 361         .sync = RING_BUFFER_SYNC_PER_CPU,
 362         .mode = RING_BUFFER_MODE_TEMPLATE,
 363         .backend = RING_BUFFER_PAGE,
 364         .output = RING_BUFFER_SPLICE,
 365         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 366         .ipi = RING_BUFFER_IPI_BARRIER,
 367         .wakeup = RING_BUFFER_WAKEUP_BY_TIMER,
 368 };
 369
 370 static
 371 struct channel *_channel_create(const char *name,
 372                                 struct ltt_channel *ltt_chan, void *buf_addr,
 373                                 size_t subbuf_size, size_t num_subbuf,
 374                                 unsigned int switch_timer_interval,
 375                                 unsigned int read_timer_interval)
 376 {
 377         return channel_create(&client_config, name, ltt_chan, buf_addr,
 378                               subbuf_size, num_subbuf, switch_timer_interval,
 379                               read_timer_interval);
 380 }
 381
 382 static
 383 void ltt_channel_destroy(struct channel *chan)
 384 {
 385         channel_destroy(chan);
 386 }
 387
 388 static
 389 struct lib_ring_buffer *ltt_buffer_read_open(struct channel *chan)
 390 {
 391         struct lib_ring_buffer *buf;
 392         int cpu;
 393
 394         for_each_channel_cpu(cpu, chan) {
 395                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 396                 if (!lib_ring_buffer_open_read(buf))
 397                         return buf;
 398         }
 399         return NULL;
 400 }
 401
 402 static
 403 void ltt_buffer_read_close(struct lib_ring_buffer *buf)
 404 {
 405         lib_ring_buffer_release_read(buf);
 406 }
 407
 408 static
 409 int ltt_event_reserve(struct lib_ring_buffer_ctx *ctx,
 410                       uint32_t event_id)
 411 {
 412         struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 413         int ret, cpu;
 414
 415         cpu = lib_ring_buffer_get_cpu(&client_config);
 416         if (cpu < 0)
 417                 return -EPERM;
 418         ctx->cpu = cpu;
 419
 420         switch (ltt_chan->header_type) {
 421         case 1: /* compact */
 422                 if (event_id > 30)
 423                         ctx->rflags |= LTT_RFLAG_EXTENDED;
 424                 break;
 425         case 2: /* large */
 426                 if (event_id > 65534)
 427                         ctx->rflags |= LTT_RFLAG_EXTENDED;
 428                 break;
 429         default:
 430                 WARN_ON_ONCE(1);
 431         }
 432
 433         ret = lib_ring_buffer_reserve(&client_config, ctx);
 434         if (ret)
 435                 goto put;
 436         ltt_write_event_header(&client_config, ctx, event_id);
 437         return 0;
 438 put:
 439         lib_ring_buffer_put_cpu(&client_config);
 440         return ret;
 441 }
 442
 443 static
 444 void ltt_event_commit(struct lib_ring_buffer_ctx *ctx)
 445 {
 446         lib_ring_buffer_commit(&client_config, ctx);
 447         lib_ring_buffer_put_cpu(&client_config);
 448 }
 449
 450 static
 451 void ltt_event_write(struct lib_ring_buffer_ctx *ctx, const void *src,
 452                      size_t len)
 453 {
 454         lib_ring_buffer_write(&client_config, ctx, src, len);
 455 }
 456
 457 static
 458 wait_queue_head_t *ltt_get_reader_wait_queue(struct channel *chan)
 459 {
 460         return &chan->read_wait;
 461 }
 462
 463 static
 464 wait_queue_head_t *ltt_get_hp_wait_queue(struct channel *chan)
 465 {
 466         return &chan->hp_wait;
 467 }
 468
 469 static
 470 int ltt_is_finalized(struct channel *chan)
 471 {
 472         return lib_ring_buffer_channel_is_finalized(chan);
 473 }
 474
 475 static
 476 int ltt_is_disabled(struct channel *chan)
 477 {
 478         return lib_ring_buffer_channel_is_disabled(chan);
 479 }
 480
 481 static struct ltt_transport ltt_relay_transport = {
 482         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
 483         .owner = THIS_MODULE,
 484         .ops = {
 485                 .channel_create = _channel_create,
 486                 .channel_destroy = ltt_channel_destroy,
 487                 .buffer_read_open = ltt_buffer_read_open,
 488                 .buffer_read_close = ltt_buffer_read_close,
 489                 .event_reserve = ltt_event_reserve,
 490                 .event_commit = ltt_event_commit,
 491                 .event_write = ltt_event_write,
 492                 .packet_avail_size = NULL,      /* Would be racy anyway */
 493                 .get_reader_wait_queue = ltt_get_reader_wait_queue,
 494                 .get_hp_wait_queue = ltt_get_hp_wait_queue,
 495                 .is_finalized = ltt_is_finalized,
 496                 .is_disabled = ltt_is_disabled,
 497         },
 498 };
 499
 500 static int __init ltt_ring_buffer_client_init(void)
 501 {
 502         /*
 503          * This vmalloc sync all also takes care of the lib ring buffer
 504          * vmalloc'd module pages when it is built as a module into LTTng.
 505          */
 506         wrapper_vmalloc_sync_all();
 507         ltt_transport_register(&ltt_relay_transport);
 508         return 0;
 509 }
 510
 511 module_init(ltt_ring_buffer_client_init);
 512
 513 static void __exit ltt_ring_buffer_client_exit(void)
 514 {
 515         ltt_transport_unregister(&ltt_relay_transport);
 516 }
 517
 518 module_exit(ltt_ring_buffer_client_exit);
 519
 520 MODULE_LICENSE("GPL and additional rights");
 521 MODULE_AUTHOR("Mathieu Desnoyers");
 522 MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING
 523                    " client");