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