src/lttng-event-notifier-notification.c

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   2  *
   3  * lttng-event-notifier-notification.c
   4  *
   5  * Copyright (C) 2020 Francis Deslauriers <francis.deslauriers@efficios.com>
   6  */
   7
   8 #include <linux/bug.h>
   9
  10 #include <lttng/lttng-bytecode.h>
  11 #include <lttng/events.h>
  12 #include <lttng/msgpack.h>
  13 #include <lttng/event-notifier-notification.h>
  14 #include <lttng/events-internal.h>
  15 #include <wrapper/barrier.h>
  16
  17 /*
  18  * The capture buffer size needs to be below 1024 bytes to avoid the
  19  * frame to be larger than the 1024 limit enforced by the kernel. If we
  20  * ever need to increase it, we will need to use a memory allocation
  21  * scheme which allows allocating temporary memory chunks from the
  22  * instrumentation sites. This could be done by adapting lttng
  23  * tp-mempool to become nmi-safe and lock-free.
  24  */
  25 #define CAPTURE_BUFFER_SIZE 512
  26
  27 struct lttng_event_notifier_notification {
  28         int notification_fd;
  29         uint64_t event_notifier_token;
  30         uint8_t capture_buf[CAPTURE_BUFFER_SIZE];
  31         struct lttng_msgpack_writer writer;
  32         bool has_captures;
  33 };
  34
  35 static
  36 int capture_enum(struct lttng_msgpack_writer *writer,
  37                 struct lttng_interpreter_output *output)
  38 {
  39         int ret;
  40
  41         /*
  42          * Enums are captured as a map containing 2 key-value pairs. Such as:
  43          * - type: enum
  44          *   value: 177
  45          */
  46         ret = lttng_msgpack_begin_map(writer, 2);
  47         if (ret) {
  48                 WARN_ON_ONCE(1);
  49                 goto end;
  50         }
  51
  52         ret = lttng_msgpack_write_str(writer, "type");
  53         if (ret) {
  54                 WARN_ON_ONCE(1);
  55                 goto end;
  56         }
  57
  58         ret = lttng_msgpack_write_str(writer, "enum");
  59         if (ret) {
  60                 WARN_ON_ONCE(1);
  61                 goto end;
  62         }
  63
  64         ret = lttng_msgpack_write_str(writer, "value");
  65         if (ret) {
  66                 WARN_ON_ONCE(1);
  67                 goto end;
  68         }
  69
  70         switch (output->type) {
  71         case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM:
  72                 ret = lttng_msgpack_write_signed_integer(writer, output->u.s);
  73                 if (ret) {
  74                         WARN_ON_ONCE(1);
  75                         goto end;
  76                 }
  77                 break;
  78         case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM:
  79                 ret = lttng_msgpack_write_signed_integer(writer, output->u.u);
  80                 if (ret) {
  81                         WARN_ON_ONCE(1);
  82                         goto end;
  83                 }
  84                 break;
  85         default:
  86                 WARN_ON(1);
  87         }
  88
  89         ret = lttng_msgpack_end_map(writer);
  90         if (ret)
  91                 WARN_ON_ONCE(1);
  92
  93 end:
  94         return ret;
  95 }
  96
  97 static
  98 int64_t capture_sequence_element_signed(uint8_t *ptr,
  99                 const struct lttng_kernel_type_integer *type)
 100 {
 101         int64_t value = 0;
 102         unsigned int size = type->size;
 103         bool byte_order_reversed = type->reverse_byte_order;
 104
 105         switch (size) {
 106         case 8:
 107                 value = *ptr;
 108                 break;
 109         case 16:
 110         {
 111                 int16_t tmp;
 112                 tmp = *(int16_t *) ptr;
 113                 if (byte_order_reversed)
 114                         __swab16s(&tmp);
 115
 116                 value = tmp;
 117                 break;
 118         }
 119         case 32:
 120         {
 121                 int32_t tmp;
 122                 tmp = *(int32_t *) ptr;
 123                 if (byte_order_reversed)
 124                         __swab32s(&tmp);
 125
 126                 value = tmp;
 127                 break;
 128         }
 129         case 64:
 130         {
 131                 int64_t tmp;
 132                 tmp = *(int64_t *) ptr;
 133                 if (byte_order_reversed)
 134                         __swab64s(&tmp);
 135
 136                 value = tmp;
 137                 break;
 138         }
 139         default:
 140                 WARN_ON(1);
 141         }
 142
 143         return value;
 144 }
 145
 146 static
 147 uint64_t capture_sequence_element_unsigned(uint8_t *ptr,
 148                 const struct lttng_kernel_type_integer *type)
 149 {
 150         uint64_t value = 0;
 151         unsigned int size = type->size;
 152         bool byte_order_reversed = type->reverse_byte_order;
 153
 154         switch (size) {
 155         case 8:
 156                 value = *ptr;
 157                 break;
 158         case 16:
 159         {
 160                 uint16_t tmp;
 161                 tmp = *(uint16_t *) ptr;
 162                 if (byte_order_reversed)
 163                         __swab16s(&tmp);
 164
 165                 value = tmp;
 166                 break;
 167         }
 168         case 32:
 169         {
 170                 uint32_t tmp;
 171                 tmp = *(uint32_t *) ptr;
 172                 if (byte_order_reversed)
 173                         __swab32s(&tmp);
 174
 175                 value = tmp;
 176                 break;
 177         }
 178         case 64:
 179         {
 180                 uint64_t tmp;
 181                 tmp = *(uint64_t *) ptr;
 182                 if (byte_order_reversed)
 183                         __swab64s(&tmp);
 184
 185                 value = tmp;
 186                 break;
 187         }
 188         default:
 189                 WARN_ON(1);
 190         }
 191
 192         return value;
 193 }
 194
 195 int capture_sequence(struct lttng_msgpack_writer *writer,
 196                 struct lttng_interpreter_output *output)
 197 {
 198         const struct lttng_kernel_type_integer *integer_type = NULL;
 199         const struct lttng_kernel_type_common *nested_type;
 200         uint8_t *ptr;
 201         bool signedness;
 202         int ret, i;
 203
 204         ret = lttng_msgpack_begin_array(writer, output->u.sequence.nr_elem);
 205         if (ret) {
 206                 WARN_ON_ONCE(1);
 207                 goto end;
 208         }
 209
 210         ptr = (uint8_t *) output->u.sequence.ptr;
 211         nested_type = output->u.sequence.nested_type;
 212         switch (nested_type->type) {
 213         case lttng_kernel_type_integer:
 214                 integer_type = lttng_kernel_get_type_integer(nested_type);
 215                 break;
 216         case lttng_kernel_type_enum:
 217                 /* Treat enumeration as an integer. */
 218                 integer_type = lttng_kernel_get_type_integer(lttng_kernel_get_type_enum(nested_type)->container_type);
 219                 break;
 220         default:
 221                 /* Capture of array of non-integer are not supported. */
 222                 WARN_ON(1);
 223         }
 224         signedness = integer_type->signedness;
 225         for (i = 0; i < output->u.sequence.nr_elem; i++) {
 226                 if (signedness) {
 227                         ret = lttng_msgpack_write_signed_integer(writer,
 228                                 capture_sequence_element_signed(ptr, integer_type));
 229                         if (ret) {
 230                                 WARN_ON_ONCE(1);
 231                                 goto end;
 232                         }
 233                 } else {
 234                         ret = lttng_msgpack_write_unsigned_integer(writer,
 235                                 capture_sequence_element_unsigned(ptr, integer_type));
 236                         if (ret) {
 237                                 WARN_ON_ONCE(1);
 238                                 goto end;
 239                         }
 240                 }
 241
 242                 /*
 243                  * We assume that alignment is smaller or equal to the size.
 244                  * This currently holds true but if it changes in the future,
 245                  * we will want to change the pointer arithmetics below to
 246                  * take into account that the next element might be further
 247                  * away.
 248                  */
 249                 WARN_ON(integer_type->alignment > integer_type->size);
 250
 251                 /* Size is in number of bits. */
 252                 ptr += (integer_type->size / CHAR_BIT) ;
 253         }
 254
 255         ret = lttng_msgpack_end_array(writer);
 256         if (ret)
 257                 WARN_ON_ONCE(1);
 258 end:
 259         return ret;
 260 }
 261
 262 static
 263 int notification_append_capture(
 264                 struct lttng_event_notifier_notification *notif,
 265                 struct lttng_interpreter_output *output)
 266 {
 267         struct lttng_msgpack_writer *writer = &notif->writer;
 268         int ret = 0;
 269
 270         switch (output->type) {
 271         case LTTNG_INTERPRETER_TYPE_S64:
 272                 ret = lttng_msgpack_write_signed_integer(writer, output->u.s);
 273                 if (ret) {
 274                         WARN_ON_ONCE(1);
 275                         goto end;
 276                 }
 277                 break;
 278         case LTTNG_INTERPRETER_TYPE_U64:
 279                 ret = lttng_msgpack_write_unsigned_integer(writer, output->u.u);
 280                 if (ret) {
 281                         WARN_ON_ONCE(1);
 282                         goto end;
 283                 }
 284                 break;
 285         case LTTNG_INTERPRETER_TYPE_STRING:
 286                 ret = lttng_msgpack_write_str(writer, output->u.str.str);
 287                 if (ret) {
 288                         WARN_ON_ONCE(1);
 289                         goto end;
 290                 }
 291                 break;
 292         case LTTNG_INTERPRETER_TYPE_SEQUENCE:
 293                 ret = capture_sequence(writer, output);
 294                 if (ret) {
 295                         WARN_ON_ONCE(1);
 296                         goto end;
 297                 }
 298                 break;
 299         case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM:
 300         case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM:
 301                 ret = capture_enum(writer, output);
 302                 if (ret) {
 303                         WARN_ON_ONCE(1);
 304                         goto end;
 305                 }
 306                 break;
 307         default:
 308                 ret = -1;
 309                 WARN_ON(1);
 310         }
 311 end:
 312         return ret;
 313 }
 314
 315 static
 316 int notification_append_empty_capture(
 317                 struct lttng_event_notifier_notification *notif)
 318 {
 319         int ret = lttng_msgpack_write_nil(&notif->writer);
 320         if (ret)
 321                 WARN_ON_ONCE(1);
 322
 323         return ret;
 324 }
 325
 326 static
 327 int notification_init(struct lttng_event_notifier_notification *notif,
 328                 struct lttng_kernel_event_notifier *event_notifier)
 329 {
 330         struct lttng_msgpack_writer *writer = &notif->writer;
 331         int ret = 0;
 332
 333         notif->has_captures = false;
 334
 335         if (event_notifier->priv->num_captures > 0) {
 336                 lttng_msgpack_writer_init(writer, notif->capture_buf,
 337                                 CAPTURE_BUFFER_SIZE);
 338
 339                 ret = lttng_msgpack_begin_array(writer, event_notifier->priv->num_captures);
 340                 if (ret) {
 341                         WARN_ON_ONCE(1);
 342                         goto end;
 343                 }
 344
 345                 notif->has_captures = true;
 346         }
 347
 348 end:
 349         return ret;
 350 }
 351
 352 static
 353 void record_error(struct lttng_kernel_event_notifier *event_notifier)
 354 {
 355
 356         struct lttng_event_notifier_group *event_notifier_group = event_notifier->priv->group;
 357         struct lttng_counter *error_counter;
 358         size_t dimension_index[1];
 359         int ret;
 360
 361         /*
 362          * lttng_smp_load_acquire paired with lttng_smp_store_release orders
 363          * creation of the error counter and setting error_counter_len
 364          * before the error_counter is used.
 365          */
 366         error_counter = lttng_smp_load_acquire(&event_notifier_group->error_counter);
 367         /* This group may not have an error counter attached to it. */
 368         if (!error_counter)
 369                 return;
 370
 371         dimension_index[0] = event_notifier->priv->error_counter_index;
 372
 373         ret = error_counter->ops->counter_add(error_counter->counter,
 374                         dimension_index, 1);
 375         if (ret)
 376                 WARN_ON_ONCE(1);
 377 }
 378
 379 static
 380 void notification_send(struct lttng_event_notifier_notification *notif,
 381                 struct lttng_kernel_event_notifier *event_notifier)
 382 {
 383         struct lttng_event_notifier_group *event_notifier_group = event_notifier->priv->group;
 384         struct lttng_kernel_ring_buffer_ctx ctx;
 385         struct lttng_kernel_abi_event_notifier_notification kernel_notif;
 386         size_t capture_buffer_content_len, reserve_size;
 387         int ret;
 388
 389         reserve_size = sizeof(kernel_notif);
 390         kernel_notif.token = event_notifier->priv->parent.user_token;
 391
 392         if (notif->has_captures) {
 393                 capture_buffer_content_len = notif->writer.write_pos - notif->writer.buffer;
 394         } else {
 395                 capture_buffer_content_len = 0;
 396         }
 397
 398         WARN_ON_ONCE(capture_buffer_content_len > CAPTURE_BUFFER_SIZE);
 399
 400         reserve_size += capture_buffer_content_len;
 401         kernel_notif.capture_buf_size = capture_buffer_content_len;
 402
 403         lib_ring_buffer_ctx_init(&ctx, event_notifier_group->chan, reserve_size,
 404                         lttng_alignof(kernel_notif), NULL);
 405         ret = event_notifier_group->ops->event_reserve(&ctx);
 406         if (ret < 0) {
 407                 record_error(event_notifier);
 408                 return;
 409         }
 410
 411         lib_ring_buffer_align_ctx(&ctx, lttng_alignof(kernel_notif));
 412
 413         /* Write the notif structure. */
 414         event_notifier_group->ops->event_write(&ctx, &kernel_notif,
 415                         sizeof(kernel_notif));
 416
 417         /*
 418          * Write the capture buffer. No need to realigned as the below is a raw
 419          * char* buffer.
 420          */
 421         event_notifier_group->ops->event_write(&ctx, &notif->capture_buf,
 422                         capture_buffer_content_len);
 423
 424         event_notifier_group->ops->event_commit(&ctx);
 425         irq_work_queue(&event_notifier_group->wakeup_pending);
 426 }
 427
 428 void lttng_event_notifier_notification_send(struct lttng_kernel_event_notifier *event_notifier,
 429                 const char *stack_data,
 430                 struct lttng_kernel_probe_ctx *probe_ctx,
 431                 struct lttng_kernel_notification_ctx *notif_ctx)
 432 {
 433         struct lttng_event_notifier_notification notif = { 0 };
 434         int ret;
 435
 436         if (unlikely(!READ_ONCE(event_notifier->parent.enabled)))
 437                 return;
 438
 439         ret = notification_init(&notif, event_notifier);
 440         if (ret) {
 441                 WARN_ON_ONCE(1);
 442                 goto end;
 443         }
 444
 445         if (unlikely(notif_ctx->eval_capture)) {
 446                 struct lttng_kernel_bytecode_runtime *capture_bc_runtime;
 447
 448                 /*
 449                  * Iterate over all the capture bytecodes. If the interpreter
 450                  * functions returns successfully, append the value of the
 451                  * `output` parameter to the capture buffer. If the interpreter
 452                  * fails, append an empty capture to the buffer.
 453                  */
 454                 list_for_each_entry_rcu(capture_bc_runtime,
 455                                 &event_notifier->priv->capture_bytecode_runtime_head, node) {
 456                         struct lttng_interpreter_output output;
 457
 458                         if (capture_bc_runtime->interpreter_func(capture_bc_runtime,
 459                                         stack_data, probe_ctx, &output) == LTTNG_KERNEL_BYTECODE_INTERPRETER_OK)
 460                                 ret = notification_append_capture(&notif, &output);
 461                         else
 462                                 ret = notification_append_empty_capture(&notif);
 463
 464                         if (ret)
 465                                 printk(KERN_WARNING "Error appending capture to notification");
 466                 }
 467         }
 468
 469         /*
 470          * Send the notification (including the capture buffer) to the
 471          * sessiond.
 472          */
 473         notification_send(&notif, event_notifier);
 474 end:
 475         return;
 476 }