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                 if (output->u.str.user) {
 287                         ret = lttng_msgpack_write_user_str(writer, output->u.str.user_str);
 288                 } else {
 289                         ret = lttng_msgpack_write_str(writer, output->u.str.str);
 290                 }
 291                 if (ret) {
 292                         WARN_ON_ONCE(1);
 293                         goto end;
 294                 }
 295                 break;
 296         case LTTNG_INTERPRETER_TYPE_SEQUENCE:
 297                 ret = capture_sequence(writer, output);
 298                 if (ret) {
 299                         WARN_ON_ONCE(1);
 300                         goto end;
 301                 }
 302                 break;
 303         case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM:
 304         case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM:
 305                 ret = capture_enum(writer, output);
 306                 if (ret) {
 307                         WARN_ON_ONCE(1);
 308                         goto end;
 309                 }
 310                 break;
 311         default:
 312                 ret = -1;
 313                 WARN_ON(1);
 314         }
 315 end:
 316         return ret;
 317 }
 318
 319 static
 320 int notification_append_empty_capture(
 321                 struct lttng_event_notifier_notification *notif)
 322 {
 323         int ret = lttng_msgpack_write_nil(&notif->writer);
 324         if (ret)
 325                 WARN_ON_ONCE(1);
 326
 327         return ret;
 328 }
 329
 330 static
 331 int notification_init(struct lttng_event_notifier_notification *notif,
 332                 struct lttng_kernel_event_notifier *event_notifier)
 333 {
 334         struct lttng_msgpack_writer *writer = &notif->writer;
 335         int ret = 0;
 336
 337         notif->has_captures = false;
 338
 339         if (event_notifier->priv->num_captures > 0) {
 340                 lttng_msgpack_writer_init(writer, notif->capture_buf,
 341                                 CAPTURE_BUFFER_SIZE);
 342
 343                 ret = lttng_msgpack_begin_array(writer, event_notifier->priv->num_captures);
 344                 if (ret) {
 345                         WARN_ON_ONCE(1);
 346                         goto end;
 347                 }
 348
 349                 notif->has_captures = true;
 350         }
 351
 352 end:
 353         return ret;
 354 }
 355
 356 static
 357 void record_error(struct lttng_kernel_event_notifier *event_notifier)
 358 {
 359
 360         struct lttng_event_notifier_group *event_notifier_group = event_notifier->priv->group;
 361         struct lttng_counter *error_counter;
 362         size_t dimension_index[1];
 363         int ret;
 364
 365         /*
 366          * lttng_smp_load_acquire paired with lttng_smp_store_release orders
 367          * creation of the error counter and setting error_counter_len
 368          * before the error_counter is used.
 369          */
 370         error_counter = lttng_smp_load_acquire(&event_notifier_group->error_counter);
 371         /* This group may not have an error counter attached to it. */
 372         if (!error_counter)
 373                 return;
 374
 375         dimension_index[0] = event_notifier->priv->error_counter_index;
 376
 377         ret = error_counter->ops->counter_add(error_counter->counter,
 378                         dimension_index, 1);
 379         if (ret)
 380                 WARN_ON_ONCE(1);
 381 }
 382
 383 static
 384 void notification_send(struct lttng_event_notifier_notification *notif,
 385                 struct lttng_kernel_event_notifier *event_notifier)
 386 {
 387         struct lttng_event_notifier_group *event_notifier_group = event_notifier->priv->group;
 388         struct lttng_kernel_ring_buffer_ctx ctx;
 389         struct lttng_kernel_abi_event_notifier_notification kernel_notif;
 390         size_t capture_buffer_content_len, reserve_size;
 391         int ret;
 392
 393         reserve_size = sizeof(kernel_notif);
 394         kernel_notif.token = event_notifier->priv->parent.user_token;
 395
 396         if (notif->has_captures) {
 397                 capture_buffer_content_len = notif->writer.write_pos - notif->writer.buffer;
 398         } else {
 399                 capture_buffer_content_len = 0;
 400         }
 401
 402         WARN_ON_ONCE(capture_buffer_content_len > CAPTURE_BUFFER_SIZE);
 403
 404         reserve_size += capture_buffer_content_len;
 405         kernel_notif.capture_buf_size = capture_buffer_content_len;
 406
 407         lib_ring_buffer_ctx_init(&ctx, event_notifier_group->chan, reserve_size,
 408                         lttng_alignof(kernel_notif), NULL);
 409         ret = event_notifier_group->ops->event_reserve(&ctx);
 410         if (ret < 0) {
 411                 record_error(event_notifier);
 412                 return;
 413         }
 414
 415         /* Write the notif structure. */
 416         event_notifier_group->ops->event_write(&ctx, &kernel_notif,
 417                         sizeof(kernel_notif), lttng_alignof(kernel_notif));
 418
 419         /*
 420          * Write the capture buffer. No need to realigned as the below is a raw
 421          * char* buffer.
 422          */
 423         event_notifier_group->ops->event_write(&ctx, &notif->capture_buf,
 424                         capture_buffer_content_len, 1);
 425
 426         event_notifier_group->ops->event_commit(&ctx);
 427         irq_work_queue(&event_notifier_group->wakeup_pending);
 428 }
 429
 430 void lttng_event_notifier_notification_send(struct lttng_kernel_event_notifier *event_notifier,
 431                 const char *stack_data,
 432                 struct lttng_kernel_probe_ctx *probe_ctx,
 433                 struct lttng_kernel_notification_ctx *notif_ctx)
 434 {
 435         struct lttng_event_notifier_notification notif = { 0 };
 436         int ret;
 437
 438         if (unlikely(!READ_ONCE(event_notifier->parent.enabled)))
 439                 return;
 440
 441         ret = notification_init(&notif, event_notifier);
 442         if (ret) {
 443                 WARN_ON_ONCE(1);
 444                 goto end;
 445         }
 446
 447         if (unlikely(notif_ctx->eval_capture)) {
 448                 struct lttng_kernel_bytecode_runtime *capture_bc_runtime;
 449
 450                 /*
 451                  * Iterate over all the capture bytecodes. If the interpreter
 452                  * functions returns successfully, append the value of the
 453                  * `output` parameter to the capture buffer. If the interpreter
 454                  * fails, append an empty capture to the buffer.
 455                  */
 456                 list_for_each_entry_rcu(capture_bc_runtime,
 457                                 &event_notifier->priv->capture_bytecode_runtime_head, node) {
 458                         struct lttng_interpreter_output output;
 459
 460                         if (capture_bc_runtime->interpreter_func(capture_bc_runtime,
 461                                         stack_data, probe_ctx, &output) == LTTNG_KERNEL_BYTECODE_INTERPRETER_OK)
 462                                 ret = notification_append_capture(&notif, &output);
 463                         else
 464                                 ret = notification_append_empty_capture(&notif);
 465
 466                         if (ret)
 467                                 printk(KERN_WARNING "Error appending capture to notification");
 468                 }
 469         }
 470
 471         /*
 472          * Send the notification (including the capture buffer) to the
 473          * sessiond.
 474          */
 475         notification_send(&notif, event_notifier);
 476 end:
 477         return;
 478 }