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 <asm/barrier.h>
   9 #include <linux/bug.h>
  10
  11 #include <lttng/lttng-bytecode.h>
  12 #include <lttng/events.h>
  13 #include <lttng/msgpack.h>
  14 #include <lttng/event-notifier-notification.h>
  15 #include <lttng/events-internal.h>
  16 #include <lttng/probe-user.h>
  17
  18 /*
  19  * The capture buffer size needs to be below 1024 bytes to avoid the
  20  * frame to be larger than the 1024 limit enforced by the kernel. If we
  21  * ever need to increase it, we will need to use a memory allocation
  22  * scheme which allows allocating temporary memory chunks from the
  23  * instrumentation sites. This could be done by adapting lttng
  24  * tp-mempool to become nmi-safe and lock-free.
  25  */
  26 #define CAPTURE_BUFFER_SIZE 512
  27
  28 #define MSG_WRITE_NIL_LEN 1
  29
  30 struct lttng_event_notifier_notification {
  31         int notification_fd;
  32         uint64_t event_notifier_token;
  33         uint8_t capture_buf[CAPTURE_BUFFER_SIZE];
  34         struct lttng_msgpack_writer writer;
  35         bool has_captures;
  36 };
  37
  38 static
  39 int capture_enum(struct lttng_msgpack_writer *writer,
  40                 struct lttng_interpreter_output *output)
  41 {
  42         int ret;
  43
  44         /*
  45          * Enums are captured as a map containing 2 key-value pairs. Such as:
  46          * - type: enum
  47          *   value: 177
  48          */
  49         ret = lttng_msgpack_begin_map(writer, 2);
  50         if (ret) {
  51                 goto end;
  52         }
  53
  54         ret = lttng_msgpack_write_str(writer, "type");
  55         if (ret) {
  56                 goto end;
  57         }
  58
  59         ret = lttng_msgpack_write_str(writer, "enum");
  60         if (ret) {
  61                 goto end;
  62         }
  63
  64         ret = lttng_msgpack_write_str(writer, "value");
  65         if (ret) {
  66                 goto end;
  67         }
  68
  69         switch (output->type) {
  70         case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM:
  71                 ret = lttng_msgpack_write_signed_integer(writer, output->u.s);
  72                 if (ret) {
  73                         goto end;
  74                 }
  75                 break;
  76         case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM:
  77                 ret = lttng_msgpack_write_signed_integer(writer, output->u.u);
  78                 if (ret) {
  79                         goto end;
  80                 }
  81                 break;
  82         default:
  83                 WARN_ON_ONCE(1);
  84                 ret = -1;
  85                 goto end;
  86         }
  87
  88         ret = lttng_msgpack_end_map(writer);
  89 end:
  90         return ret;
  91 }
  92
  93 static
  94 int capture_sequence_element_signed(uint8_t *ptr,
  95                 const struct lttng_kernel_type_integer *type,
  96                 int64_t *_value)
  97 {
  98         int64_t value = 0;
  99         unsigned int size = type->size;
 100         bool user = type->user;
 101         bool byte_order_reversed = type->reverse_byte_order;
 102
 103         switch (size) {
 104         case 8:
 105         {
 106                 int8_t tmp;
 107
 108                 if (user) {
 109                         if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(int8_t)))
 110                                 return -1;
 111                 } else {
 112                         tmp = *ptr;
 113                 }
 114                 value = tmp;
 115                 break;
 116         }
 117         case 16:
 118         {
 119                 int16_t tmp;
 120
 121                 if (user) {
 122                         if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(int16_t)))
 123                                 return -1;
 124                 } else {
 125                         tmp = *(int16_t *) ptr;
 126                 }
 127                 if (byte_order_reversed)
 128                         __swab16s(&tmp);
 129                 value = tmp;
 130                 break;
 131         }
 132         case 32:
 133         {
 134                 int32_t tmp;
 135
 136                 if (user) {
 137                         if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(int32_t)))
 138                                 return -1;
 139                 } else {
 140                         tmp = *(int32_t *) ptr;
 141                 }
 142                 if (byte_order_reversed)
 143                         __swab32s(&tmp);
 144                 value = tmp;
 145                 break;
 146         }
 147         case 64:
 148         {
 149                 int64_t tmp;
 150
 151                 if (user) {
 152                         if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(int64_t)))
 153                                 return -1;
 154                 } else {
 155                         tmp = *(int64_t *) ptr;
 156                 }
 157                 if (byte_order_reversed)
 158                         __swab64s(&tmp);
 159                 value = tmp;
 160                 break;
 161         }
 162         default:
 163                 WARN_ON_ONCE(1);
 164                 return -1;
 165         }
 166
 167         *_value = value;
 168         return 0;
 169 }
 170
 171 static
 172 int capture_sequence_element_unsigned(uint8_t *ptr,
 173                 const struct lttng_kernel_type_integer *type,
 174                 uint64_t *_value)
 175 {
 176         uint64_t value = 0;
 177         unsigned int size = type->size;
 178         bool user = type->user;
 179         bool byte_order_reversed = type->reverse_byte_order;
 180
 181         switch (size) {
 182         case 8:
 183         {
 184                 uint8_t tmp;
 185
 186                 if (user) {
 187                         if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(uint8_t)))
 188                                 return -1;
 189                 } else {
 190                         tmp = *ptr;
 191                 }
 192                 value = tmp;
 193                 break;
 194         }
 195         case 16:
 196         {
 197                 uint16_t tmp;
 198
 199                 if (user) {
 200                         if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(uint16_t)))
 201                                 return -1;
 202                 } else {
 203                         tmp = *(uint16_t *) ptr;
 204                 }
 205                 if (byte_order_reversed)
 206                         __swab16s(&tmp);
 207                 value = tmp;
 208                 break;
 209         }
 210         case 32:
 211         {
 212                 uint32_t tmp;
 213
 214                 if (user) {
 215                         if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(uint32_t)))
 216                                 return -1;
 217                 } else {
 218                         tmp = *(uint32_t *) ptr;
 219                 }
 220                 if (byte_order_reversed)
 221                         __swab32s(&tmp);
 222                 value = tmp;
 223                 break;
 224         }
 225         case 64:
 226         {
 227                 uint64_t tmp;
 228
 229                 if (user) {
 230                         if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(uint64_t)))
 231                                 return -1;
 232                 } else {
 233                         tmp = *(uint64_t *) ptr;
 234                 }
 235                 if (byte_order_reversed)
 236                         __swab64s(&tmp);
 237                 value = tmp;
 238                 break;
 239         }
 240         default:
 241                 WARN_ON_ONCE(1);
 242                 return -1;
 243         }
 244
 245         *_value = value;
 246         return 0;
 247 }
 248
 249 static
 250 int capture_sequence(struct lttng_msgpack_writer *writer,
 251                 struct lttng_interpreter_output *output)
 252 {
 253         const struct lttng_kernel_type_integer *integer_type = NULL;
 254         const struct lttng_kernel_type_common *nested_type;
 255         uint8_t *ptr;
 256         bool signedness;
 257         int ret, i;
 258
 259         ret = lttng_msgpack_begin_array(writer, output->u.sequence.nr_elem);
 260         if (ret) {
 261                 goto end;
 262         }
 263
 264         ptr = (uint8_t *) output->u.sequence.ptr;
 265         nested_type = output->u.sequence.nested_type;
 266         switch (nested_type->type) {
 267         case lttng_kernel_type_integer:
 268                 integer_type = lttng_kernel_get_type_integer(nested_type);
 269                 break;
 270         case lttng_kernel_type_enum:
 271                 /* Treat enumeration as an integer. */
 272                 integer_type = lttng_kernel_get_type_integer(lttng_kernel_get_type_enum(nested_type)->container_type);
 273                 break;
 274         default:
 275                 /* Capture of array of non-integer are not supported. */
 276                 WARN_ON_ONCE(1);
 277                 ret = -1;
 278                 goto end;
 279         }
 280         signedness = integer_type->signedness;
 281         for (i = 0; i < output->u.sequence.nr_elem; i++) {
 282                 if (signedness) {
 283                         int64_t v;
 284
 285                         ret = capture_sequence_element_signed(ptr, integer_type, &v);
 286                         if (ret) {
 287                                 goto end;
 288                         }
 289                         ret = lttng_msgpack_write_signed_integer(writer, v);
 290                         if (ret) {
 291                                 goto end;
 292                         }
 293                 } else {
 294                         uint64_t v;
 295
 296                         ret = capture_sequence_element_unsigned(ptr, integer_type, &v);
 297                         if (ret) {
 298                                 goto end;
 299                         }
 300                         ret = lttng_msgpack_write_unsigned_integer(writer, v);
 301                         if (ret) {
 302                                 goto end;
 303                         }
 304                 }
 305
 306                 /*
 307                  * We assume that alignment is smaller or equal to the size.
 308                  * This currently holds true but if it changes in the future,
 309                  * we will want to change the pointer arithmetics below to
 310                  * take into account that the next element might be further
 311                  * away.
 312                  */
 313                 WARN_ON_ONCE(integer_type->alignment > integer_type->size);
 314
 315                 /* Size is in number of bits. */
 316                 ptr += (integer_type->size / CHAR_BIT) ;
 317         }
 318
 319         ret = lttng_msgpack_end_array(writer);
 320 end:
 321         return ret;
 322 }
 323
 324 static
 325 int notification_append_capture(
 326                 struct lttng_event_notifier_notification *notif,
 327                 struct lttng_interpreter_output *output)
 328 {
 329         struct lttng_msgpack_writer *writer = &notif->writer;
 330         int ret = 0;
 331
 332         switch (output->type) {
 333         case LTTNG_INTERPRETER_TYPE_S64:
 334                 ret = lttng_msgpack_write_signed_integer(writer, output->u.s);
 335                 break;
 336         case LTTNG_INTERPRETER_TYPE_U64:
 337                 ret = lttng_msgpack_write_unsigned_integer(writer, output->u.u);
 338                 break;
 339         case LTTNG_INTERPRETER_TYPE_STRING:
 340                 if (output->u.str.user) {
 341                         ret = lttng_msgpack_write_user_str(writer, output->u.str.user_str);
 342                 } else {
 343                         ret = lttng_msgpack_write_str(writer, output->u.str.str);
 344                 }
 345                 break;
 346         case LTTNG_INTERPRETER_TYPE_SEQUENCE:
 347                 ret = capture_sequence(writer, output);
 348                 break;
 349         case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM:
 350         case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM:
 351                 ret = capture_enum(writer, output);
 352                 break;
 353         default:
 354                 ret = -1;
 355                 WARN_ON_ONCE(1);
 356         }
 357         return ret;
 358 }
 359
 360 static
 361 int notification_append_empty_capture(
 362                 struct lttng_event_notifier_notification *notif)
 363 {
 364         return lttng_msgpack_write_nil(&notif->writer);
 365 }
 366
 367 static
 368 int notification_init(struct lttng_event_notifier_notification *notif,
 369                 struct lttng_kernel_event_notifier *event_notifier)
 370 {
 371         struct lttng_msgpack_writer *writer = &notif->writer;
 372         int ret = 0;
 373
 374         notif->has_captures = false;
 375
 376         if (event_notifier->priv->num_captures > 0) {
 377                 lttng_msgpack_writer_init(writer, notif->capture_buf,
 378                                 CAPTURE_BUFFER_SIZE);
 379
 380                 ret = lttng_msgpack_begin_array(writer, event_notifier->priv->num_captures);
 381                 if (ret) {
 382                         goto end;
 383                 }
 384
 385                 notif->has_captures = true;
 386         }
 387
 388 end:
 389         return ret;
 390 }
 391
 392 static
 393 void record_error(struct lttng_kernel_event_notifier *event_notifier)
 394 {
 395
 396         struct lttng_event_notifier_group *event_notifier_group = event_notifier->priv->group;
 397         struct lttng_counter *error_counter;
 398         size_t dimension_index[1];
 399         int ret;
 400
 401         /*
 402          * smp_load_acquire paired with smp_store_release orders creation of
 403          * the error counter and setting error_counter_len before the
 404          * error_counter is used.
 405          */
 406         error_counter = smp_load_acquire(&event_notifier_group->error_counter);
 407         /* This group may not have an error counter attached to it. */
 408         if (!error_counter)
 409                 return;
 410
 411         dimension_index[0] = event_notifier->priv->error_counter_index;
 412
 413         ret = error_counter->ops->counter_add(error_counter->counter,
 414                         dimension_index, 1);
 415         if (ret)
 416                 WARN_ON_ONCE(1);
 417 }
 418
 419 static
 420 void notification_send(struct lttng_event_notifier_notification *notif,
 421                 struct lttng_kernel_event_notifier *event_notifier)
 422 {
 423         struct lttng_event_notifier_group *event_notifier_group = event_notifier->priv->group;
 424         struct lttng_kernel_ring_buffer_ctx ctx;
 425         struct lttng_kernel_abi_event_notifier_notification kernel_notif;
 426         size_t capture_buffer_content_len, reserve_size;
 427         int ret;
 428
 429         reserve_size = sizeof(kernel_notif);
 430         kernel_notif.token = event_notifier->priv->parent.user_token;
 431
 432         if (notif->has_captures) {
 433                 capture_buffer_content_len = notif->writer.write_pos - notif->writer.buffer;
 434         } else {
 435                 capture_buffer_content_len = 0;
 436         }
 437
 438         WARN_ON_ONCE(capture_buffer_content_len > CAPTURE_BUFFER_SIZE);
 439
 440         reserve_size += capture_buffer_content_len;
 441         kernel_notif.capture_buf_size = capture_buffer_content_len;
 442
 443         lib_ring_buffer_ctx_init(&ctx, event_notifier_group->chan, reserve_size,
 444                         lttng_alignof(kernel_notif), NULL);
 445         ret = event_notifier_group->ops->event_reserve(&ctx);
 446         if (ret < 0) {
 447                 record_error(event_notifier);
 448                 return;
 449         }
 450
 451         /* Write the notif structure. */
 452         event_notifier_group->ops->event_write(&ctx, &kernel_notif,
 453                         sizeof(kernel_notif), lttng_alignof(kernel_notif));
 454
 455         /*
 456          * Write the capture buffer. No need to realigned as the below is a raw
 457          * char* buffer.
 458          */
 459         event_notifier_group->ops->event_write(&ctx, &notif->capture_buf,
 460                         capture_buffer_content_len, 1);
 461
 462         event_notifier_group->ops->event_commit(&ctx);
 463         irq_work_queue(&event_notifier_group->wakeup_pending);
 464 }
 465
 466 /*
 467  * Validate that the buffer has enough room to hold empty capture fields.
 468  */
 469 static
 470 bool validate_buffer_len(struct lttng_event_notifier_notification *notif, size_t captures_left)
 471 {
 472         if (notif->writer.end_write_pos - notif->writer.write_pos < MSG_WRITE_NIL_LEN * captures_left)
 473                 return false;
 474         return true;
 475 }
 476
 477 void lttng_event_notifier_notification_send(struct lttng_kernel_event_notifier *event_notifier,
 478                 const char *stack_data,
 479                 struct lttng_kernel_probe_ctx *probe_ctx,
 480                 struct lttng_kernel_notification_ctx *notif_ctx)
 481 {
 482         struct lttng_event_notifier_notification notif = { 0 };
 483         size_t captures_left;
 484
 485         if (notification_init(&notif, event_notifier))
 486                 goto error;
 487
 488         captures_left = event_notifier->priv->num_captures;
 489         if (!validate_buffer_len(&notif, captures_left))
 490                 goto error;
 491
 492         if (unlikely(notif_ctx->eval_capture)) {
 493                 struct lttng_kernel_bytecode_runtime *capture_bc_runtime;
 494
 495                 /*
 496                  * Iterate over all the capture bytecodes. If the interpreter
 497                  * functions returns successfully, append the value of the
 498                  * `output` parameter to the capture buffer. If the interpreter
 499                  * fails, append an empty capture to the buffer.
 500                  */
 501                 list_for_each_entry_rcu(capture_bc_runtime,
 502                                 &event_notifier->priv->capture_bytecode_runtime_head, node) {
 503                         struct lttng_interpreter_output output;
 504                         uint8_t *save_pos;
 505                         int ret = -1;
 506
 507                         lttng_msgpack_save_writer_pos(&notif.writer, &save_pos);
 508                         captures_left--;
 509                         if (capture_bc_runtime->interpreter_func(capture_bc_runtime,
 510                                         stack_data, probe_ctx, &output) == LTTNG_KERNEL_BYTECODE_INTERPRETER_OK)
 511                                 ret = notification_append_capture(&notif, &output);
 512                         if (ret || !validate_buffer_len(&notif, captures_left)) {
 513                                 /*
 514                                  * On append capture error or if the generated
 515                                  * buffer data would not leave enough room to
 516                                  * write empty capture fields for the remaining
 517                                  * fields, skip the field capture by restoring
 518                                  * the msgpack writer position and writing an
 519                                  * empty capture field.
 520                                  */
 521                                 lttng_msgpack_restore_writer_pos(&notif.writer, save_pos);
 522                                 ret = notification_append_empty_capture(&notif);
 523                                 WARN_ON_ONCE(ret);
 524                         }
 525                 }
 526         }
 527
 528         if (notif.has_captures && lttng_msgpack_end_array(&notif.writer))
 529                 goto error;
 530
 531         /*
 532          * Send the notification (including the capture buffer) to the
 533          * sessiond.
 534          */
 535         notification_send(&notif, event_notifier);
 536         return;
 537
 538 error:
 539         record_error(event_notifier);
 540         return;
 541 }