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