| 1 | /* |
| 2 | * SPDX-License-Identifier: LGPL-2.1-only |
| 3 | * |
| 4 | * Copyright (C) 2020 Francis Deslauriers <francis.deslauriers@efficios.com> |
| 5 | */ |
| 6 | |
| 7 | #define _LGPL_SOURCE |
| 8 | |
| 9 | #include <assert.h> |
| 10 | #include <errno.h> |
| 11 | #include <lttng/ust-endian.h> |
| 12 | #include <usterr-signal-safe.h> |
| 13 | |
| 14 | #include "ust-events-internal.h" |
| 15 | #include "../libmsgpack/msgpack.h" |
| 16 | #include "lttng-bytecode.h" |
| 17 | #include "ust-share.h" |
| 18 | |
| 19 | /* |
| 20 | * We want this write to be atomic AND non-blocking, meaning that we |
| 21 | * want to write either everything OR nothing. |
| 22 | * According to `pipe(7)`, writes that are less than `PIPE_BUF` bytes must be |
| 23 | * atomic, so we bound the capture buffer size to the `PIPE_BUF` minus the size |
| 24 | * of the notification struct we are sending alongside the capture buffer. |
| 25 | */ |
| 26 | #define CAPTURE_BUFFER_SIZE \ |
| 27 | (PIPE_BUF - sizeof(struct lttng_ust_event_notifier_notification) - 1) |
| 28 | |
| 29 | struct lttng_event_notifier_notification { |
| 30 | int notification_fd; |
| 31 | uint64_t event_notifier_token; |
| 32 | uint8_t capture_buf[CAPTURE_BUFFER_SIZE]; |
| 33 | struct lttng_msgpack_writer writer; |
| 34 | bool has_captures; |
| 35 | }; |
| 36 | |
| 37 | static |
| 38 | void capture_enum(struct lttng_msgpack_writer *writer, |
| 39 | struct lttng_interpreter_output *output) |
| 40 | { |
| 41 | lttng_msgpack_begin_map(writer, 2); |
| 42 | lttng_msgpack_write_str(writer, "type"); |
| 43 | lttng_msgpack_write_str(writer, "enum"); |
| 44 | |
| 45 | lttng_msgpack_write_str(writer, "value"); |
| 46 | |
| 47 | switch (output->type) { |
| 48 | case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM: |
| 49 | lttng_msgpack_write_signed_integer(writer, output->u.s); |
| 50 | break; |
| 51 | case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM: |
| 52 | lttng_msgpack_write_signed_integer(writer, output->u.u); |
| 53 | break; |
| 54 | default: |
| 55 | abort(); |
| 56 | } |
| 57 | |
| 58 | lttng_msgpack_end_map(writer); |
| 59 | } |
| 60 | |
| 61 | static |
| 62 | int64_t capture_sequence_element_signed(uint8_t *ptr, |
| 63 | const struct lttng_integer_type *type) |
| 64 | { |
| 65 | int64_t value; |
| 66 | unsigned int size = type->size; |
| 67 | bool byte_order_reversed = type->reverse_byte_order; |
| 68 | |
| 69 | switch (size) { |
| 70 | case 8: |
| 71 | value = *ptr; |
| 72 | break; |
| 73 | case 16: |
| 74 | { |
| 75 | int16_t tmp; |
| 76 | tmp = *(int16_t *) ptr; |
| 77 | if (byte_order_reversed) |
| 78 | tmp = bswap_16(tmp); |
| 79 | |
| 80 | value = tmp; |
| 81 | break; |
| 82 | } |
| 83 | case 32: |
| 84 | { |
| 85 | int32_t tmp; |
| 86 | tmp = *(int32_t *) ptr; |
| 87 | if (byte_order_reversed) |
| 88 | tmp = bswap_32(tmp); |
| 89 | |
| 90 | value = tmp; |
| 91 | break; |
| 92 | } |
| 93 | case 64: |
| 94 | { |
| 95 | int64_t tmp; |
| 96 | tmp = *(int64_t *) ptr; |
| 97 | if (byte_order_reversed) |
| 98 | tmp = bswap_64(tmp); |
| 99 | |
| 100 | value = tmp; |
| 101 | break; |
| 102 | } |
| 103 | default: |
| 104 | abort(); |
| 105 | } |
| 106 | |
| 107 | return value; |
| 108 | } |
| 109 | |
| 110 | static |
| 111 | uint64_t capture_sequence_element_unsigned(uint8_t *ptr, |
| 112 | const struct lttng_integer_type *type) |
| 113 | { |
| 114 | uint64_t value; |
| 115 | unsigned int size = type->size; |
| 116 | bool byte_order_reversed = type->reverse_byte_order; |
| 117 | |
| 118 | switch (size) { |
| 119 | case 8: |
| 120 | value = *ptr; |
| 121 | break; |
| 122 | case 16: |
| 123 | { |
| 124 | uint16_t tmp; |
| 125 | tmp = *(uint16_t *) ptr; |
| 126 | if (byte_order_reversed) |
| 127 | tmp = bswap_16(tmp); |
| 128 | |
| 129 | value = tmp; |
| 130 | break; |
| 131 | } |
| 132 | case 32: |
| 133 | { |
| 134 | uint32_t tmp; |
| 135 | tmp = *(uint32_t *) ptr; |
| 136 | if (byte_order_reversed) |
| 137 | tmp = bswap_32(tmp); |
| 138 | |
| 139 | value = tmp; |
| 140 | break; |
| 141 | } |
| 142 | case 64: |
| 143 | { |
| 144 | uint64_t tmp; |
| 145 | tmp = *(uint64_t *) ptr; |
| 146 | if (byte_order_reversed) |
| 147 | tmp = bswap_64(tmp); |
| 148 | |
| 149 | value = tmp; |
| 150 | break; |
| 151 | } |
| 152 | default: |
| 153 | abort(); |
| 154 | } |
| 155 | |
| 156 | return value; |
| 157 | } |
| 158 | |
| 159 | static |
| 160 | void capture_sequence(struct lttng_msgpack_writer *writer, |
| 161 | struct lttng_interpreter_output *output) |
| 162 | { |
| 163 | const struct lttng_integer_type *integer_type; |
| 164 | const struct lttng_type *nested_type; |
| 165 | uint8_t *ptr; |
| 166 | bool signedness; |
| 167 | int i; |
| 168 | |
| 169 | lttng_msgpack_begin_array(writer, output->u.sequence.nr_elem); |
| 170 | |
| 171 | ptr = (uint8_t *) output->u.sequence.ptr; |
| 172 | nested_type = output->u.sequence.nested_type; |
| 173 | switch (nested_type->atype) { |
| 174 | case atype_integer: |
| 175 | integer_type = &nested_type->u.integer; |
| 176 | break; |
| 177 | case atype_enum_nestable: |
| 178 | /* Treat enumeration as an integer. */ |
| 179 | integer_type = &nested_type->u.enum_nestable.container_type->u.integer; |
| 180 | break; |
| 181 | default: |
| 182 | /* Capture of array of non-integer are not supported. */ |
| 183 | abort(); |
| 184 | } |
| 185 | signedness = integer_type->signedness; |
| 186 | for (i = 0; i < output->u.sequence.nr_elem; i++) { |
| 187 | if (signedness) { |
| 188 | lttng_msgpack_write_signed_integer(writer, |
| 189 | capture_sequence_element_signed(ptr, integer_type)); |
| 190 | } else { |
| 191 | lttng_msgpack_write_unsigned_integer(writer, |
| 192 | capture_sequence_element_unsigned(ptr, integer_type)); |
| 193 | } |
| 194 | |
| 195 | /* |
| 196 | * We assume that alignment is smaller or equal to the size. |
| 197 | * This currently holds true but if it changes in the future, |
| 198 | * we will want to change the pointer arithmetics below to |
| 199 | * take into account that the next element might be further |
| 200 | * away. |
| 201 | */ |
| 202 | assert(integer_type->alignment <= integer_type->size); |
| 203 | |
| 204 | /* Size is in number of bits. */ |
| 205 | ptr += (integer_type->size / CHAR_BIT) ; |
| 206 | } |
| 207 | |
| 208 | lttng_msgpack_end_array(writer); |
| 209 | } |
| 210 | |
| 211 | static |
| 212 | void notification_init(struct lttng_event_notifier_notification *notif, |
| 213 | struct lttng_event_notifier *event_notifier) |
| 214 | { |
| 215 | struct lttng_msgpack_writer *writer = ¬if->writer; |
| 216 | |
| 217 | notif->event_notifier_token = event_notifier->user_token; |
| 218 | notif->notification_fd = event_notifier->group->notification_fd; |
| 219 | notif->has_captures = false; |
| 220 | |
| 221 | if (event_notifier->num_captures > 0) { |
| 222 | lttng_msgpack_writer_init(writer, notif->capture_buf, |
| 223 | CAPTURE_BUFFER_SIZE); |
| 224 | |
| 225 | lttng_msgpack_begin_array(writer, event_notifier->num_captures); |
| 226 | notif->has_captures = true; |
| 227 | } |
| 228 | } |
| 229 | |
| 230 | static |
| 231 | void notification_append_capture( |
| 232 | struct lttng_event_notifier_notification *notif, |
| 233 | struct lttng_interpreter_output *output) |
| 234 | { |
| 235 | struct lttng_msgpack_writer *writer = ¬if->writer; |
| 236 | |
| 237 | switch (output->type) { |
| 238 | case LTTNG_INTERPRETER_TYPE_S64: |
| 239 | lttng_msgpack_write_signed_integer(writer, output->u.s); |
| 240 | break; |
| 241 | case LTTNG_INTERPRETER_TYPE_U64: |
| 242 | lttng_msgpack_write_unsigned_integer(writer, output->u.u); |
| 243 | break; |
| 244 | case LTTNG_INTERPRETER_TYPE_DOUBLE: |
| 245 | lttng_msgpack_write_double(writer, output->u.d); |
| 246 | break; |
| 247 | case LTTNG_INTERPRETER_TYPE_STRING: |
| 248 | lttng_msgpack_write_str(writer, output->u.str.str); |
| 249 | break; |
| 250 | case LTTNG_INTERPRETER_TYPE_SEQUENCE: |
| 251 | capture_sequence(writer, output); |
| 252 | break; |
| 253 | case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM: |
| 254 | case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM: |
| 255 | capture_enum(writer, output); |
| 256 | break; |
| 257 | default: |
| 258 | abort(); |
| 259 | } |
| 260 | } |
| 261 | |
| 262 | static |
| 263 | void notification_append_empty_capture( |
| 264 | struct lttng_event_notifier_notification *notif) |
| 265 | { |
| 266 | lttng_msgpack_write_nil(¬if->writer); |
| 267 | } |
| 268 | |
| 269 | static void record_error(struct lttng_event_notifier *event_notifier) |
| 270 | { |
| 271 | struct lttng_event_notifier_group *event_notifier_group = |
| 272 | event_notifier->group; |
| 273 | struct lttng_counter *error_counter; |
| 274 | size_t dimension_index[1]; |
| 275 | int ret; |
| 276 | |
| 277 | error_counter = CMM_LOAD_SHARED(event_notifier_group->error_counter); |
| 278 | /* |
| 279 | * load-acquire paired with store-release orders creation of the |
| 280 | * error counter and setting error_counter_len before the |
| 281 | * error_counter is used. |
| 282 | * Currently a full memory barrier is used, which could be |
| 283 | * turned into acquire-release barriers. |
| 284 | */ |
| 285 | cmm_smp_mb(); |
| 286 | /* This group may not have an error counter attached to it. */ |
| 287 | if (!error_counter) |
| 288 | return; |
| 289 | |
| 290 | dimension_index[0] = event_notifier->error_counter_index; |
| 291 | ret = event_notifier_group->error_counter->ops->counter_add( |
| 292 | error_counter->counter, dimension_index, 1); |
| 293 | if (ret) |
| 294 | WARN_ON_ONCE(1); |
| 295 | } |
| 296 | |
| 297 | static |
| 298 | void notification_send(struct lttng_event_notifier_notification *notif, |
| 299 | struct lttng_event_notifier *event_notifier) |
| 300 | { |
| 301 | ssize_t ret; |
| 302 | size_t content_len; |
| 303 | int iovec_count = 1; |
| 304 | struct lttng_ust_event_notifier_notification ust_notif = {0}; |
| 305 | struct iovec iov[2]; |
| 306 | |
| 307 | assert(notif); |
| 308 | |
| 309 | ust_notif.token = event_notifier->user_token; |
| 310 | |
| 311 | /* |
| 312 | * Prepare sending the notification from multiple buffers using an |
| 313 | * array of `struct iovec`. The first buffer of the vector is |
| 314 | * notification structure itself and is always present. |
| 315 | */ |
| 316 | iov[0].iov_base = &ust_notif; |
| 317 | iov[0].iov_len = sizeof(ust_notif); |
| 318 | |
| 319 | if (notif->has_captures) { |
| 320 | /* |
| 321 | * If captures were requested, the second buffer of the array |
| 322 | * is the capture buffer. |
| 323 | */ |
| 324 | assert(notif->writer.buffer); |
| 325 | content_len = notif->writer.write_pos - notif->writer.buffer; |
| 326 | |
| 327 | assert(content_len > 0 && content_len <= CAPTURE_BUFFER_SIZE); |
| 328 | |
| 329 | iov[1].iov_base = notif->capture_buf; |
| 330 | iov[1].iov_len = content_len; |
| 331 | |
| 332 | iovec_count++; |
| 333 | } else { |
| 334 | content_len = 0; |
| 335 | } |
| 336 | |
| 337 | /* |
| 338 | * Update the capture buffer size so that receiver of the buffer will |
| 339 | * know how much to expect. |
| 340 | */ |
| 341 | ust_notif.capture_buf_size = content_len; |
| 342 | |
| 343 | /* Send all the buffers. */ |
| 344 | ret = ust_patient_writev(notif->notification_fd, iov, iovec_count); |
| 345 | if (ret == -1) { |
| 346 | if (errno == EAGAIN) { |
| 347 | record_error(event_notifier); |
| 348 | DBG("Cannot send event_notifier notification without blocking: %s", |
| 349 | strerror(errno)); |
| 350 | } else { |
| 351 | DBG("Error to sending event notifier notification: %s", |
| 352 | strerror(errno)); |
| 353 | abort(); |
| 354 | } |
| 355 | } |
| 356 | } |
| 357 | |
| 358 | void lttng_event_notifier_notification_send( |
| 359 | struct lttng_event_notifier *event_notifier, |
| 360 | const char *stack_data) |
| 361 | { |
| 362 | /* |
| 363 | * This function is called from the probe, we must do dynamic |
| 364 | * allocation in this context. |
| 365 | */ |
| 366 | struct lttng_event_notifier_notification notif = {0}; |
| 367 | |
| 368 | notification_init(¬if, event_notifier); |
| 369 | |
| 370 | if (caa_unlikely(!cds_list_empty(&event_notifier->capture_bytecode_runtime_head))) { |
| 371 | struct lttng_bytecode_runtime *capture_bc_runtime; |
| 372 | |
| 373 | /* |
| 374 | * Iterate over all the capture bytecodes. If the interpreter |
| 375 | * functions returns successfully, append the value of the |
| 376 | * `output` parameter to the capture buffer. If the interpreter |
| 377 | * fails, append an empty capture to the buffer. |
| 378 | */ |
| 379 | cds_list_for_each_entry(capture_bc_runtime, |
| 380 | &event_notifier->capture_bytecode_runtime_head, node) { |
| 381 | struct lttng_interpreter_output output; |
| 382 | |
| 383 | if (capture_bc_runtime->interpreter_funcs.capture(capture_bc_runtime, |
| 384 | stack_data, &output) & LTTNG_INTERPRETER_RECORD_FLAG) |
| 385 | notification_append_capture(¬if, &output); |
| 386 | else |
| 387 | notification_append_empty_capture(¬if); |
| 388 | } |
| 389 | } |
| 390 | |
| 391 | /* |
| 392 | * Send the notification (including the capture buffer) to the |
| 393 | * sessiond. |
| 394 | */ |
| 395 | notification_send(¬if, event_notifier); |
| 396 | } |