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 int capture_sequence(struct lttng_msgpack_writer *writer,
 250                 struct lttng_interpreter_output *output)
 251 {
 252         const struct lttng_kernel_type_integer *integer_type = NULL;
 253         const struct lttng_kernel_type_common *nested_type;
 254         uint8_t *ptr;
 255         bool signedness;
 256         int ret, i;
 257
 258         ret = lttng_msgpack_begin_array(writer, output->u.sequence.nr_elem);
 259         if (ret) {
 260                 goto end;
 261         }
 262
 263         ptr = (uint8_t *) output->u.sequence.ptr;
 264         nested_type = output->u.sequence.nested_type;
 265         switch (nested_type->type) {
 266         case lttng_kernel_type_integer:
 267                 integer_type = lttng_kernel_get_type_integer(nested_type);
 268                 break;
 269         case lttng_kernel_type_enum:
 270                 /* Treat enumeration as an integer. */
 271                 integer_type = lttng_kernel_get_type_integer(lttng_kernel_get_type_enum(nested_type)->container_type);
 272                 break;
 273         default:
 274                 /* Capture of array of non-integer are not supported. */
 275                 WARN_ON_ONCE(1);
 276                 ret = -1;
 277                 goto end;
 278         }
 279         signedness = integer_type->signedness;
 280         for (i = 0; i < output->u.sequence.nr_elem; i++) {
 281                 if (signedness) {
 282                         int64_t v;
 283
 284                         ret = capture_sequence_element_signed(ptr, integer_type, &v);
 285                         if (ret) {
 286                                 goto end;
 287                         }
 288                         ret = lttng_msgpack_write_signed_integer(writer, v);
 289                         if (ret) {
 290                                 goto end;
 291                         }
 292                 } else {
 293                         uint64_t v;
 294
 295                         ret = capture_sequence_element_unsigned(ptr, integer_type, &v);
 296                         if (ret) {
 297                                 goto end;
 298                         }
 299                         ret = lttng_msgpack_write_unsigned_integer(writer, v);
 300                         if (ret) {
 301                                 goto end;
 302                         }
 303                 }
 304
 305                 /*
 306                  * We assume that alignment is smaller or equal to the size.
 307                  * This currently holds true but if it changes in the future,
 308                  * we will want to change the pointer arithmetics below to
 309                  * take into account that the next element might be further
 310                  * away.
 311                  */
 312                 WARN_ON_ONCE(integer_type->alignment > integer_type->size);
 313
 314                 /* Size is in number of bits. */
 315                 ptr += (integer_type->size / CHAR_BIT) ;
 316         }
 317
 318         ret = lttng_msgpack_end_array(writer);
 319 end:
 320         return ret;
 321 }
 322
 323 static
 324 int notification_append_capture(
 325                 struct lttng_event_notifier_notification *notif,
 326                 struct lttng_interpreter_output *output)
 327 {
 328         struct lttng_msgpack_writer *writer = &notif->writer;
 329         int ret = 0;
 330
 331         switch (output->type) {
 332         case LTTNG_INTERPRETER_TYPE_S64:
 333                 ret = lttng_msgpack_write_signed_integer(writer, output->u.s);
 334                 break;
 335         case LTTNG_INTERPRETER_TYPE_U64:
 336                 ret = lttng_msgpack_write_unsigned_integer(writer, output->u.u);
 337                 break;
 338         case LTTNG_INTERPRETER_TYPE_STRING:
 339                 if (output->u.str.user) {
 340                         ret = lttng_msgpack_write_user_str(writer, output->u.str.user_str);
 341                 } else {
 342                         ret = lttng_msgpack_write_str(writer, output->u.str.str);
 343                 }
 344                 break;
 345         case LTTNG_INTERPRETER_TYPE_SEQUENCE:
 346                 ret = capture_sequence(writer, output);
 347                 break;
 348         case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM:
 349         case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM:
 350                 ret = capture_enum(writer, output);
 351                 break;
 352         default:
 353                 ret = -1;
 354                 WARN_ON_ONCE(1);
 355         }
 356         return ret;
 357 }
 358
 359 static
 360 int notification_append_empty_capture(
 361                 struct lttng_event_notifier_notification *notif)
 362 {
 363         return lttng_msgpack_write_nil(&notif->writer);
 364 }
 365
 366 static
 367 int notification_init(struct lttng_event_notifier_notification *notif,
 368                 struct lttng_kernel_event_notifier *event_notifier)
 369 {
 370         struct lttng_msgpack_writer *writer = &notif->writer;
 371         int ret = 0;
 372
 373         notif->has_captures = false;
 374
 375         if (event_notifier->priv->num_captures > 0) {
 376                 lttng_msgpack_writer_init(writer, notif->capture_buf,
 377                                 CAPTURE_BUFFER_SIZE);
 378
 379                 ret = lttng_msgpack_begin_array(writer, event_notifier->priv->num_captures);
 380                 if (ret) {
 381                         goto end;
 382                 }
 383
 384                 notif->has_captures = true;
 385         }
 386
 387 end:
 388         return ret;
 389 }
 390
 391 static
 392 void record_error(struct lttng_kernel_event_notifier *event_notifier)
 393 {
 394
 395         struct lttng_event_notifier_group *event_notifier_group = event_notifier->priv->group;
 396         struct lttng_counter *error_counter;
 397         size_t dimension_index[1];
 398         int ret;
 399
 400         /*
 401          * smp_load_acquire paired with smp_store_release orders creation of
 402          * the error counter and setting error_counter_len before the
 403          * error_counter is used.
 404          */
 405         error_counter = smp_load_acquire(&event_notifier_group->error_counter);
 406         /* This group may not have an error counter attached to it. */
 407         if (!error_counter)
 408                 return;
 409
 410         dimension_index[0] = event_notifier->priv->error_counter_index;
 411
 412         ret = error_counter->ops->counter_add(error_counter->counter,
 413                         dimension_index, 1);
 414         if (ret)
 415                 WARN_ON_ONCE(1);
 416 }
 417
 418 static
 419 void notification_send(struct lttng_event_notifier_notification *notif,
 420                 struct lttng_kernel_event_notifier *event_notifier)
 421 {
 422         struct lttng_event_notifier_group *event_notifier_group = event_notifier->priv->group;
 423         struct lttng_kernel_ring_buffer_ctx ctx;
 424         struct lttng_kernel_abi_event_notifier_notification kernel_notif;
 425         size_t capture_buffer_content_len, reserve_size;
 426         int ret;
 427
 428         reserve_size = sizeof(kernel_notif);
 429         kernel_notif.token = event_notifier->priv->parent.user_token;
 430
 431         if (notif->has_captures) {
 432                 capture_buffer_content_len = notif->writer.write_pos - notif->writer.buffer;
 433         } else {
 434                 capture_buffer_content_len = 0;
 435         }
 436
 437         WARN_ON_ONCE(capture_buffer_content_len > CAPTURE_BUFFER_SIZE);
 438
 439         reserve_size += capture_buffer_content_len;
 440         kernel_notif.capture_buf_size = capture_buffer_content_len;
 441
 442         lib_ring_buffer_ctx_init(&ctx, event_notifier_group->chan, reserve_size,
 443                         lttng_alignof(kernel_notif), NULL);
 444         ret = event_notifier_group->ops->event_reserve(&ctx);
 445         if (ret < 0) {
 446                 record_error(event_notifier);
 447                 return;
 448         }
 449
 450         /* Write the notif structure. */
 451         event_notifier_group->ops->event_write(&ctx, &kernel_notif,
 452                         sizeof(kernel_notif), lttng_alignof(kernel_notif));
 453
 454         /*
 455          * Write the capture buffer. No need to realigned as the below is a raw
 456          * char* buffer.
 457          */
 458         event_notifier_group->ops->event_write(&ctx, &notif->capture_buf,
 459                         capture_buffer_content_len, 1);
 460
 461         event_notifier_group->ops->event_commit(&ctx);
 462         irq_work_queue(&event_notifier_group->wakeup_pending);
 463 }
 464
 465 /*
 466  * Validate that the buffer has enough room to hold empty capture fields.
 467  */
 468 static
 469 bool validate_buffer_len(struct lttng_event_notifier_notification *notif, size_t captures_left)
 470 {
 471         if (notif->writer.end_write_pos - notif->writer.write_pos < MSG_WRITE_NIL_LEN * captures_left)
 472                 return false;
 473         return true;
 474 }
 475
 476 void lttng_event_notifier_notification_send(struct lttng_kernel_event_notifier *event_notifier,
 477                 const char *stack_data,
 478                 struct lttng_kernel_probe_ctx *probe_ctx,
 479                 struct lttng_kernel_notification_ctx *notif_ctx)
 480 {
 481         struct lttng_event_notifier_notification notif = { 0 };
 482         size_t captures_left;
 483
 484         if (notification_init(&notif, event_notifier))
 485                 goto error;
 486
 487         captures_left = event_notifier->priv->num_captures;
 488         if (!validate_buffer_len(&notif, captures_left))
 489                 goto error;
 490
 491         if (unlikely(notif_ctx->eval_capture)) {
 492                 struct lttng_kernel_bytecode_runtime *capture_bc_runtime;
 493
 494                 /*
 495                  * Iterate over all the capture bytecodes. If the interpreter
 496                  * functions returns successfully, append the value of the
 497                  * `output` parameter to the capture buffer. If the interpreter
 498                  * fails, append an empty capture to the buffer.
 499                  */
 500                 list_for_each_entry_rcu(capture_bc_runtime,
 501                                 &event_notifier->priv->capture_bytecode_runtime_head, node) {
 502                         struct lttng_interpreter_output output;
 503                         uint8_t *save_pos;
 504                         int ret = -1;
 505
 506                         lttng_msgpack_save_writer_pos(&notif.writer, &save_pos);
 507                         captures_left--;
 508                         if (capture_bc_runtime->interpreter_func(capture_bc_runtime,
 509                                         stack_data, probe_ctx, &output) == LTTNG_KERNEL_BYTECODE_INTERPRETER_OK)
 510                                 ret = notification_append_capture(&notif, &output);
 511                         if (ret || !validate_buffer_len(&notif, captures_left)) {
 512                                 /*
 513                                  * On append capture error or if the generated
 514                                  * buffer data would not leave enough room to
 515                                  * write empty capture fields for the remaining
 516                                  * fields, skip the field capture by restoring
 517                                  * the msgpack writer position and writing an
 518                                  * empty capture field.
 519                                  */
 520                                 lttng_msgpack_restore_writer_pos(&notif.writer, save_pos);
 521                                 ret = notification_append_empty_capture(&notif);
 522                                 WARN_ON_ONCE(ret);
 523                         }
 524                 }
 525         }
 526
 527         if (notif.has_captures && lttng_msgpack_end_array(&notif.writer))
 528                 goto error;
 529
 530         /*
 531          * Send the notification (including the capture buffer) to the
 532          * sessiond.
 533          */
 534         notification_send(&notif, event_notifier);
 535         return;
 536
 537 error:
 538         record_error(event_notifier);
 539         return;
 540 }