src/lttng-ring-buffer-event-notifier-client.h

   1 /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
   2  *
   3  * lttng-ring-buffer-event-notifier-client.h
   4  *
   5  * LTTng lib ring buffer event notifier client template.
   6  *
   7  * Copyright (C) 2010-2020 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  */
   9
  10 #include <linux/limits.h>
  11 #include <linux/module.h>
  12 #include <linux/types.h>
  13 #include <wrapper/vmalloc.h>    /* for wrapper_vmalloc_sync_mappings() */
  14 #include <lttng/abi.h>
  15 #include <lttng/events.h>
  16 #include <lttng/events-internal.h>
  17 #include <lttng/tracer.h>
  18 #include <wrapper/limits.h>
  19
  20 static struct lttng_transport lttng_relay_transport;
  21
  22 struct event_notifier_packet_header {
  23         uint8_t  header_end[0];
  24 };
  25
  26 struct event_notifier_record_header {
  27         uint32_t payload_len;           /* in bytes */
  28         uint8_t header_end[0];          /* End of header */
  29 };
  30
  31 static const struct lttng_kernel_ring_buffer_config client_config;
  32
  33 static inline
  34 u64 lib_ring_buffer_clock_read(struct lttng_kernel_ring_buffer_channel *chan)
  35 {
  36         return 0;
  37 }
  38
  39 static inline
  40 size_t record_header_size(const struct lttng_kernel_ring_buffer_config *config,
  41                                  struct lttng_kernel_ring_buffer_channel *chan, size_t offset,
  42                                  size_t *pre_header_padding,
  43                                  struct lttng_kernel_ring_buffer_ctx *ctx,
  44                                  void *client_ctx)
  45 {
  46         size_t orig_offset = offset;
  47         size_t padding;
  48
  49         padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
  50         offset += padding;
  51
  52         offset += sizeof(uint32_t);
  53
  54         *pre_header_padding = padding;
  55
  56         return offset - orig_offset;
  57 }
  58
  59 #include <ringbuffer/api.h>
  60
  61 static u64 client_ring_buffer_clock_read(struct lttng_kernel_ring_buffer_channel *chan)
  62 {
  63         return 0;
  64 }
  65
  66 static
  67 size_t client_record_header_size(const struct lttng_kernel_ring_buffer_config *config,
  68                                  struct lttng_kernel_ring_buffer_channel *chan, size_t offset,
  69                                  size_t *pre_header_padding,
  70                                  struct lttng_kernel_ring_buffer_ctx *ctx,
  71                                  void *client_ctx)
  72 {
  73         return record_header_size(config, chan, offset,
  74                                   pre_header_padding, ctx, client_ctx);
  75 }
  76
  77 /**
  78  * client_packet_header_size - called on buffer-switch to a new sub-buffer
  79  *
  80  * Return header size without padding after the structure. Don't use packed
  81  * structure because gcc generates inefficient code on some architectures
  82  * (powerpc, mips..)
  83  */
  84 static size_t client_packet_header_size(void)
  85 {
  86         return offsetof(struct event_notifier_packet_header, header_end);
  87 }
  88
  89 static void client_buffer_begin(struct lttng_kernel_ring_buffer *buf, u64 tsc,
  90                                 unsigned int subbuf_idx)
  91 {
  92 }
  93
  94 /*
  95  * offset is assumed to never be 0 here : never deliver a completely empty
  96  * subbuffer. data_size is between 1 and subbuf_size.
  97  */
  98 static void client_buffer_end(struct lttng_kernel_ring_buffer *buf, u64 tsc,
  99                               unsigned int subbuf_idx, unsigned long data_size,
 100                               const struct lttng_kernel_ring_buffer_ctx *ctx)
 101 {
 102 }
 103
 104 static int client_buffer_create(struct lttng_kernel_ring_buffer *buf, void *priv,
 105                                 int cpu, const char *name)
 106 {
 107         return 0;
 108 }
 109
 110 static void client_buffer_finalize(struct lttng_kernel_ring_buffer *buf, void *priv, int cpu)
 111 {
 112 }
 113
 114 static int client_timestamp_begin(const struct lttng_kernel_ring_buffer_config *config,
 115                 struct lttng_kernel_ring_buffer *buf, uint64_t *timestamp_begin)
 116 {
 117         return -ENOSYS;
 118 }
 119
 120 static int client_timestamp_end(const struct lttng_kernel_ring_buffer_config *config,
 121                         struct lttng_kernel_ring_buffer *bufb,
 122                         uint64_t *timestamp_end)
 123 {
 124         return -ENOSYS;
 125 }
 126
 127 static int client_events_discarded(const struct lttng_kernel_ring_buffer_config *config,
 128                         struct lttng_kernel_ring_buffer *bufb,
 129                         uint64_t *events_discarded)
 130 {
 131         return -ENOSYS;
 132 }
 133
 134 static int client_current_timestamp(const struct lttng_kernel_ring_buffer_config *config,
 135                 struct lttng_kernel_ring_buffer *bufb,
 136                 uint64_t *ts)
 137 {
 138         return -ENOSYS;
 139 }
 140
 141 static int client_content_size(const struct lttng_kernel_ring_buffer_config *config,
 142                         struct lttng_kernel_ring_buffer *bufb,
 143                         uint64_t *content_size)
 144 {
 145         return -ENOSYS;
 146 }
 147
 148 static int client_packet_size(const struct lttng_kernel_ring_buffer_config *config,
 149                         struct lttng_kernel_ring_buffer *bufb,
 150                         uint64_t *packet_size)
 151 {
 152         return -ENOSYS;
 153 }
 154
 155 static int client_stream_id(const struct lttng_kernel_ring_buffer_config *config,
 156                         struct lttng_kernel_ring_buffer *bufb,
 157                         uint64_t *stream_id)
 158 {
 159         return -ENOSYS;
 160 }
 161
 162 static int client_sequence_number(const struct lttng_kernel_ring_buffer_config *config,
 163                         struct lttng_kernel_ring_buffer *bufb,
 164                         uint64_t *seq)
 165 {
 166         return -ENOSYS;
 167 }
 168
 169 static
 170 int client_instance_id(const struct lttng_kernel_ring_buffer_config *config,
 171                 struct lttng_kernel_ring_buffer *bufb,
 172                 uint64_t *id)
 173 {
 174         return -ENOSYS;
 175 }
 176
 177 static void client_record_get(const struct lttng_kernel_ring_buffer_config *config,
 178         struct lttng_kernel_ring_buffer_channel *chan, struct lttng_kernel_ring_buffer *buf,
 179         size_t offset, size_t *header_len,
 180         size_t *payload_len, u64 *timestamp)
 181 {
 182         struct event_notifier_record_header header;
 183         int ret;
 184
 185         ret = lib_ring_buffer_read(&buf->backend, offset, &header,
 186                         offsetof(struct event_notifier_record_header, header_end));
 187         CHAN_WARN_ON(chan, ret != offsetof(struct event_notifier_record_header, header_end));
 188         *header_len = offsetof(struct event_notifier_record_header, header_end);
 189         *payload_len = header.payload_len;
 190         *timestamp = 0;
 191 }
 192
 193 static const struct lttng_kernel_ring_buffer_config client_config = {
 194         .cb.ring_buffer_clock_read = client_ring_buffer_clock_read,
 195         .cb.record_header_size = client_record_header_size,
 196         .cb.subbuffer_header_size = client_packet_header_size,
 197         .cb.buffer_begin = client_buffer_begin,
 198         .cb.buffer_end = client_buffer_end,
 199         .cb.buffer_create = client_buffer_create,
 200         .cb.buffer_finalize = client_buffer_finalize,
 201         .cb.record_get = client_record_get,
 202
 203         .tsc_bits = 0,
 204         .alloc = RING_BUFFER_ALLOC_GLOBAL,
 205         .sync = RING_BUFFER_SYNC_GLOBAL,
 206         .mode = RING_BUFFER_MODE_TEMPLATE,
 207         .backend = RING_BUFFER_PAGE,
 208         .output = RING_BUFFER_OUTPUT_TEMPLATE,
 209         .oops = RING_BUFFER_OOPS_CONSISTENCY,
 210         .ipi = RING_BUFFER_NO_IPI_BARRIER,
 211         .wakeup = RING_BUFFER_WAKEUP_BY_WRITER,
 212 };
 213
 214 static
 215 void release_priv_ops(void *priv_ops)
 216 {
 217         module_put(THIS_MODULE);
 218 }
 219
 220 static
 221 void lttng_channel_destroy(struct lttng_kernel_ring_buffer_channel *chan)
 222 {
 223         channel_destroy(chan);
 224 }
 225
 226 static
 227 struct lttng_kernel_ring_buffer_channel *_channel_create(const char *name,
 228                                 void *priv, void *buf_addr,
 229                                 size_t subbuf_size, size_t num_subbuf,
 230                                 unsigned int switch_timer_interval,
 231                                 unsigned int read_timer_interval)
 232 {
 233         struct lttng_event_notifier_group *event_notifier_group = priv;
 234         struct lttng_kernel_ring_buffer_channel *chan;
 235
 236         chan = channel_create(&client_config, name,
 237                               event_notifier_group, buf_addr,
 238                               subbuf_size, num_subbuf, switch_timer_interval,
 239                               read_timer_interval);
 240         if (chan) {
 241                 /*
 242                  * Ensure this module is not unloaded before we finish
 243                  * using lttng_relay_transport.ops.
 244                  */
 245                 if (!try_module_get(THIS_MODULE)) {
 246                         printk(KERN_WARNING "LTTng: Can't lock event_notifier transport module.\n");
 247                         goto error;
 248                 }
 249                 chan->backend.priv_ops = &lttng_relay_transport.ops;
 250                 chan->backend.release_priv_ops = release_priv_ops;
 251         }
 252         return chan;
 253
 254 error:
 255         lttng_channel_destroy(chan);
 256         return NULL;
 257 }
 258
 259 static
 260 struct lttng_kernel_ring_buffer *lttng_buffer_read_open(struct lttng_kernel_ring_buffer_channel *chan)
 261 {
 262         struct lttng_kernel_ring_buffer *buf;
 263
 264         buf = channel_get_ring_buffer(&client_config, chan, 0);
 265         if (!lib_ring_buffer_open_read(buf))
 266                 return buf;
 267         return NULL;
 268 }
 269
 270 static
 271 int lttng_buffer_has_read_closed_stream(struct lttng_kernel_ring_buffer_channel *chan)
 272 {
 273         struct lttng_kernel_ring_buffer *buf;
 274         int cpu;
 275
 276         for_each_channel_cpu(cpu, chan) {
 277                 buf = channel_get_ring_buffer(&client_config, chan, cpu);
 278                 if (!atomic_long_read(&buf->active_readers))
 279                         return 1;
 280         }
 281         return 0;
 282 }
 283
 284 static
 285 void lttng_buffer_read_close(struct lttng_kernel_ring_buffer *buf)
 286 {
 287         lib_ring_buffer_release_read(buf);
 288 }
 289
 290 static
 291 void lttng_write_event_notifier_header(const struct lttng_kernel_ring_buffer_config *config,
 292                             struct lttng_kernel_ring_buffer_ctx *ctx)
 293 {
 294         uint32_t data_size;
 295
 296         WARN_ON_ONCE(ctx->data_size > U32_MAX);
 297
 298         data_size = (uint32_t) ctx->data_size;
 299
 300         lib_ring_buffer_write(config, ctx, &data_size, sizeof(data_size));
 301
 302         lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
 303 }
 304
 305 static
 306 int lttng_event_reserve(struct lttng_kernel_ring_buffer_ctx *ctx)
 307 {
 308         struct lttng_kernel_ring_buffer_channel *chan = ctx->client_priv;
 309         int ret;
 310
 311         memset(&ctx->priv, 0, sizeof(ctx->priv));
 312         ctx->priv.chan = chan;
 313
 314         ret = lib_ring_buffer_reserve(&client_config, ctx, NULL);
 315         if (ret)
 316                 return ret;
 317         lib_ring_buffer_backend_get_pages(&client_config, ctx,
 318                         &ctx->priv.backend_pages);
 319
 320         lttng_write_event_notifier_header(&client_config, ctx);
 321         return 0;
 322 }
 323
 324 static
 325 void lttng_event_commit(struct lttng_kernel_ring_buffer_ctx *ctx)
 326 {
 327         lib_ring_buffer_commit(&client_config, ctx);
 328 }
 329
 330 static
 331 void lttng_event_write(struct lttng_kernel_ring_buffer_ctx *ctx, const void *src,
 332                      size_t len, size_t alignment)
 333 {
 334         lib_ring_buffer_align_ctx(ctx, alignment);
 335         lib_ring_buffer_write(&client_config, ctx, src, len);
 336 }
 337
 338 static
 339 void lttng_event_write_from_user(struct lttng_kernel_ring_buffer_ctx *ctx,
 340                                const void __user *src, size_t len, size_t alignment)
 341 {
 342         lib_ring_buffer_align_ctx(ctx, alignment);
 343         lib_ring_buffer_copy_from_user_inatomic(&client_config, ctx, src, len);
 344 }
 345
 346 static
 347 void lttng_event_memset(struct lttng_kernel_ring_buffer_ctx *ctx,
 348                 int c, size_t len)
 349 {
 350         lib_ring_buffer_memset(&client_config, ctx, c, len);
 351 }
 352
 353 static
 354 void lttng_event_strcpy(struct lttng_kernel_ring_buffer_ctx *ctx, const char *src,
 355                 size_t len)
 356 {
 357         lib_ring_buffer_strcpy(&client_config, ctx, src, len, '#');
 358 }
 359
 360 static
 361 size_t lttng_packet_avail_size(struct lttng_kernel_ring_buffer_channel *chan)
 362 {
 363         unsigned long o_begin;
 364         struct lttng_kernel_ring_buffer *buf;
 365
 366         buf = chan->backend.buf;        /* Only for global buffer ! */
 367         o_begin = v_read(&client_config, &buf->offset);
 368         if (subbuf_offset(o_begin, chan) != 0) {
 369                 return chan->backend.subbuf_size - subbuf_offset(o_begin, chan);
 370         } else {
 371                 return chan->backend.subbuf_size - subbuf_offset(o_begin, chan)
 372                         - sizeof(struct event_notifier_packet_header);
 373         }
 374 }
 375
 376 static
 377 wait_queue_head_t *lttng_get_writer_buf_wait_queue(struct lttng_kernel_ring_buffer_channel *chan, int cpu)
 378 {
 379         struct lttng_kernel_ring_buffer *buf = channel_get_ring_buffer(&client_config,
 380                                         chan, cpu);
 381         return &buf->write_wait;
 382 }
 383
 384 static
 385 wait_queue_head_t *lttng_get_hp_wait_queue(struct lttng_kernel_ring_buffer_channel *chan)
 386 {
 387         return &chan->hp_wait;
 388 }
 389
 390 static
 391 int lttng_is_finalized(struct lttng_kernel_ring_buffer_channel *chan)
 392 {
 393         return lib_ring_buffer_channel_is_finalized(chan);
 394 }
 395
 396 static
 397 int lttng_is_disabled(struct lttng_kernel_ring_buffer_channel *chan)
 398 {
 399         return lib_ring_buffer_channel_is_disabled(chan);
 400 }
 401
 402 static struct lttng_transport lttng_relay_transport = {
 403         .name = "relay-" RING_BUFFER_MODE_TEMPLATE_STRING,
 404         .owner = THIS_MODULE,
 405         .ops = {
 406                 .priv = __LTTNG_COMPOUND_LITERAL(struct lttng_kernel_channel_buffer_ops_private, {
 407                         .pub = &lttng_relay_transport.ops,
 408                         .channel_create = _channel_create,
 409                         .channel_destroy = lttng_channel_destroy,
 410                         .buffer_read_open = lttng_buffer_read_open,
 411                         .buffer_has_read_closed_stream =
 412                                 lttng_buffer_has_read_closed_stream,
 413                         .buffer_read_close = lttng_buffer_read_close,
 414                         .packet_avail_size = lttng_packet_avail_size,
 415                         .get_writer_buf_wait_queue = lttng_get_writer_buf_wait_queue,
 416                         .get_hp_wait_queue = lttng_get_hp_wait_queue,
 417                         .is_finalized = lttng_is_finalized,
 418                         .is_disabled = lttng_is_disabled,
 419                         .timestamp_begin = client_timestamp_begin,
 420                         .timestamp_end = client_timestamp_end,
 421                         .events_discarded = client_events_discarded,
 422                         .content_size = client_content_size,
 423                         .packet_size = client_packet_size,
 424                         .stream_id = client_stream_id,
 425                         .current_timestamp = client_current_timestamp,
 426                         .sequence_number = client_sequence_number,
 427                         .instance_id = client_instance_id,
 428                 }),
 429                 .event_reserve = lttng_event_reserve,
 430                 .event_commit = lttng_event_commit,
 431                 .event_write_from_user = lttng_event_write_from_user,
 432                 .event_memset = lttng_event_memset,
 433                 .event_write = lttng_event_write,
 434                 .event_strcpy = lttng_event_strcpy,
 435         },
 436 };
 437
 438 static int __init lttng_ring_buffer_event_notifier_client_init(void)
 439 {
 440         /*
 441          * This vmalloc sync all also takes care of the lib ring buffer
 442          * vmalloc'd module pages when it is built as a module into LTTng.
 443          */
 444         wrapper_vmalloc_sync_mappings();
 445         lttng_transport_register(&lttng_relay_transport);
 446         return 0;
 447 }
 448
 449 module_init(lttng_ring_buffer_event_notifier_client_init);
 450
 451 static void __exit lttng_ring_buffer_event_notifier_client_exit(void)
 452 {
 453         lttng_transport_unregister(&lttng_relay_transport);
 454 }
 455
 456 module_exit(lttng_ring_buffer_event_notifier_client_exit);
 457
 458 MODULE_LICENSE("GPL and additional rights");
 459 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
 460 MODULE_DESCRIPTION("LTTng ring buffer " RING_BUFFER_MODE_TEMPLATE_STRING
 461                    " client");
 462 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
 463         __stringify(LTTNG_MODULES_MINOR_VERSION) "."
 464         __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
 465         LTTNG_MODULES_EXTRAVERSION);