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 /*
  59  * record_header_size - Calculate the header size and padding necessary.
  60  * @config: ring buffer instance configuration
  61  * @chan: channel
  62  * @offset: offset in the write buffer
  63  * @pre_header_padding: padding to add before the header (output)
  64  * @ctx: reservation context
  65  *
  66  * Returns the event header size (including padding).
  67  *
  68  * The payload must itself determine its own alignment from the biggest type it
  69  * contains.
  70  */
  71 static __inline__
  72 unsigned char record_header_size(const struct lib_ring_buffer_config *config,
  73                                  struct channel *chan, size_t offset,
  74                                  size_t *pre_header_padding,
  75                                  struct lib_ring_buffer_ctx *ctx)
  76 {
  77         struct ltt_channel *ltt_chan = channel_get_private(chan);
  78         size_t orig_offset = offset;
  79         size_t padding;
  80
  81         switch (ltt_chan->header_type) {
  82         case 1: /* compact */
  83                 padding = lib_ring_buffer_align(offset, ltt_alignof(uint32_t));
  84                 offset += padding;
  85                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
  86                         offset += sizeof(uint32_t);     /* id and timestamp */
  87                 } else {
  88                         /* Minimum space taken by 5-bit id */
  89                         offset += sizeof(uint8_t);
  90                         /* Align extended struct on largest member */
  91                         offset += lib_ring_buffer_align(offset, ltt_alignof(uint64_t));
  92                         offset += sizeof(uint32_t);     /* id */
  93                         offset += lib_ring_buffer_align(offset, ltt_alignof(uint64_t));
  94                         offset += sizeof(uint64_t);     /* timestamp */
  95                 }
  96                 break;
  97         case 2: /* large */
  98                 padding = lib_ring_buffer_align(offset, ltt_alignof(uint16_t));
  99                 offset += padding;
 100                 offset += sizeof(uint16_t);
 101                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 102                         offset += lib_ring_buffer_align(offset, ltt_alignof(uint32_t));
 103                         offset += sizeof(uint32_t);     /* timestamp */
 104                 } else {
 105                         /* Align extended struct on largest member */
 106                         offset += lib_ring_buffer_align(offset, ltt_alignof(uint64_t));
 107                         offset += sizeof(uint32_t);     /* id */
 108                         offset += lib_ring_buffer_align(offset, ltt_alignof(uint64_t));
 109                         offset += sizeof(uint64_t);     /* timestamp */
 110
 111                 }
 112                 break;
 113         default:
 114                 WARN_ON_ONCE(1);
 115         }
 116
 117         *pre_header_padding = padding;
 118         return offset - orig_offset;
 119 }
 120
 121 #include "wrapper/ringbuffer/api.h"
 122
 123 extern
 124 void ltt_write_event_header_slow(const struct lib_ring_buffer_config *config,
 125                                  struct lib_ring_buffer_ctx *ctx,
 126                                  uint32_t event_id);
 127
 128 /*
 129  * ltt_write_event_header
 130  *
 131  * Writes the event header to the offset (already aligned on 32-bits).
 132  *
 133  * @config: ring buffer instance configuration
 134  * @ctx: reservation context
 135  * @event_id: event ID
 136  */
 137 static __inline__
 138 void ltt_write_event_header(const struct lib_ring_buffer_config *config,
 139                             struct lib_ring_buffer_ctx *ctx,
 140                             uint32_t event_id)
 141 {
 142         struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 143
 144         if (unlikely(ctx->rflags))
 145                 goto slow_path;
 146
 147         switch (ltt_chan->header_type) {
 148         case 1: /* compact */
 149         {
 150                 uint32_t id_time = 0;
 151
 152                 bt_bitfield_write(&id_time, uint32_t, 0, 5, event_id);
 153                 bt_bitfield_write(&id_time, uint32_t, 5, 27, ctx->tsc);
 154                 lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 155                 break;
 156         }
 157         case 2: /* large */
 158         {
 159                 uint32_t timestamp = (uint32_t) ctx->tsc;
 160
 161                 lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 162                 lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint32_t));
 163                 lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 164                 break;
 165         }
 166         default:
 167                 WARN_ON_ONCE(1);
 168         }
 169         return;
 170
 171 slow_path:
 172         ltt_write_event_header_slow(config, ctx, event_id);
 173 }
 174
 175 void ltt_write_event_header_slow(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
 181         switch (ltt_chan->header_type) {
 182         case 1: /* compact */
 183                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 184                         uint32_t id_time = 0;
 185
 186                         bt_bitfield_write(&id_time, uint32_t, 0, 5, event_id);
 187                         bt_bitfield_write(&id_time, uint32_t, 5, 27, ctx->tsc);
 188                         lib_ring_buffer_write(config, ctx, &id_time, sizeof(id_time));
 189                 } else {
 190                         uint8_t id = 0;
 191                         uint32_t event_id = (uint32_t) event_id;
 192                         uint64_t timestamp = ctx->tsc;
 193
 194                         bt_bitfield_write(&id, uint8_t, 0, 5, 31);
 195                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 196                         /* Align extended struct on largest member */
 197                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
 198                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 199                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
 200                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 201                 }
 202                 break;
 203         case 2: /* large */
 204         {
 205                 if (!(ctx->rflags & (RING_BUFFER_RFLAG_FULL_TSC | LTT_RFLAG_EXTENDED))) {
 206                         uint32_t timestamp = (uint32_t) ctx->tsc;
 207
 208                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 209                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint32_t));
 210                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 211                 } else {
 212                         uint16_t id = 65535;
 213                         uint64_t timestamp = ctx->tsc;
 214
 215                         lib_ring_buffer_write(config, ctx, &id, sizeof(id));
 216                         /* Align extended struct on largest member */
 217                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
 218                         lib_ring_buffer_write(config, ctx, &event_id, sizeof(event_id));
 219                         lib_ring_buffer_align_ctx(ctx, ltt_alignof(uint64_t));
 220                         lib_ring_buffer_write(config, ctx, &timestamp, sizeof(timestamp));
 221                 }
 222                 break;
 223         }
 224         default:
 225                 WARN_ON_ONCE(1);
 226         }
 227 }
 228
 229 static const struct lib_ring_buffer_config client_config;
 230
 231 static u64 client_ring_buffer_clock_read(struct channel *chan)
 232 {
 233         return lib_ring_buffer_clock_read(chan);
 234 }
 235
 236 static
 237 size_t client_record_header_size(const struct lib_ring_buffer_config *config,
 238                                  struct channel *chan, size_t offset,
 239                                  size_t *pre_header_padding,
 240                                  struct lib_ring_buffer_ctx *ctx)
 241 {
 242         return record_header_size(config, chan, offset,
 243                                   pre_header_padding, ctx);
 244 }
 245
 246 /**
 247  * client_packet_header_size - called on buffer-switch to a new sub-buffer
 248  *
 249  * Return header size without padding after the structure. Don't use packed
 250  * structure because gcc generates inefficient code on some architectures
 251  * (powerpc, mips..)
 252  */
 253 static size_t client_packet_header_size(void)
 254 {
 255         return offsetof(struct packet_header, ctx.header_end);
 256 }
 257
 258 static void client_buffer_begin(struct lib_ring_buffer *buf, u64 tsc,
 259                                 unsigned int subbuf_idx)
 260 {
 261         struct channel *chan = buf->backend.chan;
 262         struct packet_header *header =
 263                 (struct packet_header *)
 264                         lib_ring_buffer_offset_address(&buf->backend,
 265                                 subbuf_idx * chan->backend.subbuf_size);
 266         struct ltt_channel *ltt_chan = channel_get_private(chan);
 267         struct ltt_session *session = ltt_chan->session;
 268
 269         header->magic = CTF_MAGIC_NUMBER;
 270         memcpy(header->uuid, session->uuid.b, sizeof(session->uuid));
 271         header->stream_id = ltt_chan->id;
 272         header->ctx.timestamp_begin = tsc;
 273         header->ctx.timestamp_end = 0;
 274         header->ctx.events_discarded = 0;
 275         header->ctx.content_size = 0xFFFFFFFF; /* for debugging */
 276         header->ctx.packet_size = 0xFFFFFFFF;
 277         header->ctx.cpu_id = buf->backend.cpu;
 278 }
 279
 280 /*
 281  * offset is assumed to never be 0 here : never deliver a completely empty
 282  * subbuffer. data_size is between 1 and subbuf_size.
 283  */
 284 static void client_buffer_end(struct lib_ring_buffer *buf, u64 tsc,
 285                               unsigned int subbuf_idx, unsigned long data_size)
 286 {
 287         struct channel *chan = buf->backend.chan;
 288         struct packet_header *header =
 289                 (struct packet_header *)
 290                         lib_ring_buffer_offset_address(&buf->backend,
 291                                 subbuf_idx * chan->backend.subbuf_size);
 292         unsigned long records_lost = 0;
 293
 294         header->ctx.timestamp_end = tsc;
 295         header->ctx.content_size = data_size * CHAR_BIT;        /* in bits */
 296         header->ctx.packet_size = PAGE_ALIGN(data_size) * CHAR_BIT; /* in bits */
 297         records_lost += lib_ring_buffer_get_records_lost_full(&client_config, buf);
 298         records_lost += lib_ring_buffer_get_records_lost_wrap(&client_config, buf);
 299         records_lost += lib_ring_buffer_get_records_lost_big(&client_config, buf);
 300         header->ctx.events_discarded = records_lost;
 301 }
 302
 303 static int client_buffer_create(struct lib_ring_buffer *buf, void *priv,
 304                                 int cpu, const char *name)
 305 {
 306         return 0;
 307 }
 308
 309 static void client_buffer_finalize(struct lib_ring_buffer *buf, void *priv, int cpu)
 310 {
 311 }
 312
 313 static const struct lib_ring_buffer_config client_config = {
 314         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 315         .cb.record_header_size = client_record_header_size,
 316         .cb.subbuffer_header_size = client_packet_header_size,
 317         .cb.buffer_begin = client_buffer_begin,
 318         .cb.buffer_end = client_buffer_end,
 319         .cb.buffer_create = client_buffer_create,
 320         .cb.buffer_finalize = client_buffer_finalize,
 321
 322         .tsc_bits = 32,
 323         .alloc = RING_BUFFER_ALLOC_PER_CPU,
 324         .sync = RING_BUFFER_SYNC_PER_CPU,
 325         .mode = RING_BUFFER_MODE_TEMPLATE,
 326         .backend = RING_BUFFER_PAGE,
 327         .output = RING_BUFFER_SPLICE,
 328         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 329         .ipi = RING_BUFFER_IPI_BARRIER,
 330         .wakeup = RING_BUFFER_WAKEUP_BY_TIMER,
 331 };
 332
 333 static
 334 struct channel *_channel_create(const char *name,
 335                                 struct ltt_channel *ltt_chan, void *buf_addr,
 336                                 size_t subbuf_size, size_t num_subbuf,
 337                                 unsigned int switch_timer_interval,
 338                                 unsigned int read_timer_interval)
 339 {
 340         return channel_create(&client_config, name, ltt_chan, buf_addr,
 341                               subbuf_size, num_subbuf, switch_timer_interval,
 342                               read_timer_interval);
 343 }
 344
 345 static
 346 void ltt_channel_destroy(struct channel *chan)
 347 {
 348         channel_destroy(chan);
 349 }
 350
 351 static
 352 struct lib_ring_buffer *ltt_buffer_read_open(struct channel *chan)
 353 {
 354         struct lib_ring_buffer *buf;
 355         int cpu;
 356
 357         for_each_channel_cpu(cpu, chan) {
 358                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 359                 if (!lib_ring_buffer_open_read(buf))
 360                         return buf;
 361         }
 362         return NULL;
 363 }
 364
 365 static
 366 void ltt_buffer_read_close(struct lib_ring_buffer *buf)
 367 {
 368         lib_ring_buffer_release_read(buf);
 369
 370 }
 371
 372 static
 373 int ltt_event_reserve(struct lib_ring_buffer_ctx *ctx,
 374                       uint32_t event_id)
 375 {
 376         struct ltt_channel *ltt_chan = channel_get_private(ctx->chan);
 377         int ret, cpu;
 378
 379         cpu = lib_ring_buffer_get_cpu(&client_config);
 380         if (cpu < 0)
 381                 return -EPERM;
 382         ctx->cpu = cpu;
 383
 384         switch (ltt_chan->header_type) {
 385         case 1: /* compact */
 386                 if (event_id > 30)
 387                         ctx->rflags |= LTT_RFLAG_EXTENDED;
 388                 break;
 389         case 2: /* large */
 390                 if (event_id > 65534)
 391                         ctx->rflags |= LTT_RFLAG_EXTENDED;
 392                 break;
 393         default:
 394                 WARN_ON_ONCE(1);
 395         }
 396
 397         ret = lib_ring_buffer_reserve(&client_config, ctx);
 398         if (ret)
 399                 goto put;
 400         ltt_write_event_header(&client_config, ctx, event_id);
 401         return 0;
 402 put:
 403         lib_ring_buffer_put_cpu(&client_config);
 404         return ret;
 405 }
 406
 407 static
 408 void ltt_event_commit(struct lib_ring_buffer_ctx *ctx)
 409 {
 410         lib_ring_buffer_commit(&client_config, ctx);
 411         lib_ring_buffer_put_cpu(&client_config);
 412 }
 413
 414 static
 415 void ltt_event_write(struct lib_ring_buffer_ctx *ctx, const void *src,
 416                      size_t len)
 417 {
 418         lib_ring_buffer_write(&client_config, ctx, src, len);
 419 }
 420
 421 static
 422 wait_queue_head_t *ltt_get_reader_wait_queue(struct ltt_channel *chan)
 423 {
 424         return &chan->chan->read_wait;
 425 }
 426
 427 static struct ltt_transport ltt_relay_transport = {
 428         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
 429         .owner = THIS_MODULE,
 430         .ops = {
 431                 .channel_create = _channel_create,
 432                 .channel_destroy = ltt_channel_destroy,
 433                 .buffer_read_open = ltt_buffer_read_open,
 434                 .buffer_read_close = ltt_buffer_read_close,
 435                 .event_reserve = ltt_event_reserve,
 436                 .event_commit = ltt_event_commit,
 437                 .event_write = ltt_event_write,
 438                 .packet_avail_size = NULL,      /* Would be racy anyway */
 439                 .get_reader_wait_queue = ltt_get_reader_wait_queue,
 440         },
 441 };
 442
 443 static int __init ltt_ring_buffer_client_init(void)
 444 {
 445         /*
 446          * This vmalloc sync all also takes care of the lib ring buffer
 447          * vmalloc'd module pages when it is built as a module into LTTng.
 448          */
 449         wrapper_vmalloc_sync_all();
 450         printk(KERN_INFO "LTT : ltt ring buffer client init\n");
 451         ltt_transport_register(&ltt_relay_transport);
 452         return 0;
 453 }
 454
 455 module_init(ltt_ring_buffer_client_init);
 456
 457 static void __exit ltt_ring_buffer_client_exit(void)
 458 {
 459         printk(KERN_INFO "LTT : ltt ring buffer client exit\n");
 460         ltt_transport_unregister(&ltt_relay_transport);
 461 }
 462
 463 module_exit(ltt_ring_buffer_client_exit);
 464
 465 MODULE_LICENSE("GPL and additional rights");
 466 MODULE_AUTHOR("Mathieu Desnoyers");
 467 MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING
 468                    " client");