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