liblttng-ust/lttng-filter.c

   1 /*
   2  * lttng-filter.c
   3  *
   4  * LTTng UST filter code.
   5  *
   6  * Copyright (C) 2010-2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a copy
   9  * of this software and associated documentation files (the "Software"), to deal
  10  * in the Software without restriction, including without limitation the rights
  11  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  12  * copies of the Software, and to permit persons to whom the Software is
  13  * furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included in
  16  * all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  21  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  23  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  24  * SOFTWARE.
  25  */
  26
  27 #define _LGPL_SOURCE
  28 #include <stddef.h>
  29 #include <stdint.h>
  30
  31 #include <urcu/rculist.h>
  32
  33 #include "lttng-filter.h"
  34 #include "ust-events-internal.h"
  35
  36 static const char *opnames[] = {
  37         [ FILTER_OP_UNKNOWN ] = "UNKNOWN",
  38
  39         [ FILTER_OP_RETURN ] = "RETURN",
  40
  41         /* binary */
  42         [ FILTER_OP_MUL ] = "MUL",
  43         [ FILTER_OP_DIV ] = "DIV",
  44         [ FILTER_OP_MOD ] = "MOD",
  45         [ FILTER_OP_PLUS ] = "PLUS",
  46         [ FILTER_OP_MINUS ] = "MINUS",
  47         [ FILTER_OP_BIT_RSHIFT ] = "BIT_RSHIFT",
  48         [ FILTER_OP_BIT_LSHIFT ] = "BIT_LSHIFT",
  49         [ FILTER_OP_BIT_AND ] = "BIT_AND",
  50         [ FILTER_OP_BIT_OR ] = "BIT_OR",
  51         [ FILTER_OP_BIT_XOR ] = "BIT_XOR",
  52
  53         /* binary comparators */
  54         [ FILTER_OP_EQ ] = "EQ",
  55         [ FILTER_OP_NE ] = "NE",
  56         [ FILTER_OP_GT ] = "GT",
  57         [ FILTER_OP_LT ] = "LT",
  58         [ FILTER_OP_GE ] = "GE",
  59         [ FILTER_OP_LE ] = "LE",
  60
  61         /* string binary comparators */
  62         [ FILTER_OP_EQ_STRING ] = "EQ_STRING",
  63         [ FILTER_OP_NE_STRING ] = "NE_STRING",
  64         [ FILTER_OP_GT_STRING ] = "GT_STRING",
  65         [ FILTER_OP_LT_STRING ] = "LT_STRING",
  66         [ FILTER_OP_GE_STRING ] = "GE_STRING",
  67         [ FILTER_OP_LE_STRING ] = "LE_STRING",
  68
  69         /* s64 binary comparators */
  70         [ FILTER_OP_EQ_S64 ] = "EQ_S64",
  71         [ FILTER_OP_NE_S64 ] = "NE_S64",
  72         [ FILTER_OP_GT_S64 ] = "GT_S64",
  73         [ FILTER_OP_LT_S64 ] = "LT_S64",
  74         [ FILTER_OP_GE_S64 ] = "GE_S64",
  75         [ FILTER_OP_LE_S64 ] = "LE_S64",
  76
  77         /* double binary comparators */
  78         [ FILTER_OP_EQ_DOUBLE ] = "EQ_DOUBLE",
  79         [ FILTER_OP_NE_DOUBLE ] = "NE_DOUBLE",
  80         [ FILTER_OP_GT_DOUBLE ] = "GT_DOUBLE",
  81         [ FILTER_OP_LT_DOUBLE ] = "LT_DOUBLE",
  82         [ FILTER_OP_GE_DOUBLE ] = "GE_DOUBLE",
  83         [ FILTER_OP_LE_DOUBLE ] = "LE_DOUBLE",
  84
  85         /* Mixed S64-double binary comparators */
  86         [ FILTER_OP_EQ_DOUBLE_S64 ] = "EQ_DOUBLE_S64",
  87         [ FILTER_OP_NE_DOUBLE_S64 ] = "NE_DOUBLE_S64",
  88         [ FILTER_OP_GT_DOUBLE_S64 ] = "GT_DOUBLE_S64",
  89         [ FILTER_OP_LT_DOUBLE_S64 ] = "LT_DOUBLE_S64",
  90         [ FILTER_OP_GE_DOUBLE_S64 ] = "GE_DOUBLE_S64",
  91         [ FILTER_OP_LE_DOUBLE_S64 ] = "LE_DOUBLE_S64",
  92
  93         [ FILTER_OP_EQ_S64_DOUBLE ] = "EQ_S64_DOUBLE",
  94         [ FILTER_OP_NE_S64_DOUBLE ] = "NE_S64_DOUBLE",
  95         [ FILTER_OP_GT_S64_DOUBLE ] = "GT_S64_DOUBLE",
  96         [ FILTER_OP_LT_S64_DOUBLE ] = "LT_S64_DOUBLE",
  97         [ FILTER_OP_GE_S64_DOUBLE ] = "GE_S64_DOUBLE",
  98         [ FILTER_OP_LE_S64_DOUBLE ] = "LE_S64_DOUBLE",
  99
 100         /* unary */
 101         [ FILTER_OP_UNARY_PLUS ] = "UNARY_PLUS",
 102         [ FILTER_OP_UNARY_MINUS ] = "UNARY_MINUS",
 103         [ FILTER_OP_UNARY_NOT ] = "UNARY_NOT",
 104         [ FILTER_OP_UNARY_PLUS_S64 ] = "UNARY_PLUS_S64",
 105         [ FILTER_OP_UNARY_MINUS_S64 ] = "UNARY_MINUS_S64",
 106         [ FILTER_OP_UNARY_NOT_S64 ] = "UNARY_NOT_S64",
 107         [ FILTER_OP_UNARY_PLUS_DOUBLE ] = "UNARY_PLUS_DOUBLE",
 108         [ FILTER_OP_UNARY_MINUS_DOUBLE ] = "UNARY_MINUS_DOUBLE",
 109         [ FILTER_OP_UNARY_NOT_DOUBLE ] = "UNARY_NOT_DOUBLE",
 110
 111         /* logical */
 112         [ FILTER_OP_AND ] = "AND",
 113         [ FILTER_OP_OR ] = "OR",
 114
 115         /* load field ref */
 116         [ FILTER_OP_LOAD_FIELD_REF ] = "LOAD_FIELD_REF",
 117         [ FILTER_OP_LOAD_FIELD_REF_STRING ] = "LOAD_FIELD_REF_STRING",
 118         [ FILTER_OP_LOAD_FIELD_REF_SEQUENCE ] = "LOAD_FIELD_REF_SEQUENCE",
 119         [ FILTER_OP_LOAD_FIELD_REF_S64 ] = "LOAD_FIELD_REF_S64",
 120         [ FILTER_OP_LOAD_FIELD_REF_DOUBLE ] = "LOAD_FIELD_REF_DOUBLE",
 121
 122         /* load from immediate operand */
 123         [ FILTER_OP_LOAD_STRING ] = "LOAD_STRING",
 124         [ FILTER_OP_LOAD_S64 ] = "LOAD_S64",
 125         [ FILTER_OP_LOAD_DOUBLE ] = "LOAD_DOUBLE",
 126
 127         /* cast */
 128         [ FILTER_OP_CAST_TO_S64 ] = "CAST_TO_S64",
 129         [ FILTER_OP_CAST_DOUBLE_TO_S64 ] = "CAST_DOUBLE_TO_S64",
 130         [ FILTER_OP_CAST_NOP ] = "CAST_NOP",
 131
 132         /* get context ref */
 133         [ FILTER_OP_GET_CONTEXT_REF ] = "GET_CONTEXT_REF",
 134         [ FILTER_OP_GET_CONTEXT_REF_STRING ] = "GET_CONTEXT_REF_STRING",
 135         [ FILTER_OP_GET_CONTEXT_REF_S64 ] = "GET_CONTEXT_REF_S64",
 136         [ FILTER_OP_GET_CONTEXT_REF_DOUBLE ] = "GET_CONTEXT_REF_DOUBLE",
 137
 138         /* load userspace field ref */
 139         [ FILTER_OP_LOAD_FIELD_REF_USER_STRING ] = "LOAD_FIELD_REF_USER_STRING",
 140         [ FILTER_OP_LOAD_FIELD_REF_USER_SEQUENCE ] = "LOAD_FIELD_REF_USER_SEQUENCE",
 141
 142         /*
 143          * load immediate star globbing pattern (literal string)
 144          * from immediate.
 145          */
 146         [ FILTER_OP_LOAD_STAR_GLOB_STRING ] = "LOAD_STAR_GLOB_STRING",
 147
 148         /* globbing pattern binary operator: apply to */
 149         [ FILTER_OP_EQ_STAR_GLOB_STRING ] = "EQ_STAR_GLOB_STRING",
 150         [ FILTER_OP_NE_STAR_GLOB_STRING ] = "NE_STAR_GLOB_STRING",
 151
 152         /*
 153          * Instructions for recursive traversal through composed types.
 154          */
 155         [ FILTER_OP_GET_CONTEXT_ROOT ] = "GET_CONTEXT_ROOT",
 156         [ FILTER_OP_GET_APP_CONTEXT_ROOT ] = "GET_APP_CONTEXT_ROOT",
 157         [ FILTER_OP_GET_PAYLOAD_ROOT ] = "GET_PAYLOAD_ROOT",
 158
 159         [ FILTER_OP_GET_SYMBOL ] = "GET_SYMBOL",
 160         [ FILTER_OP_GET_SYMBOL_FIELD ] = "GET_SYMBOL_FIELD",
 161         [ FILTER_OP_GET_INDEX_U16 ] = "GET_INDEX_U16",
 162         [ FILTER_OP_GET_INDEX_U64 ] = "GET_INDEX_U64",
 163
 164         [ FILTER_OP_LOAD_FIELD ] = "LOAD_FIELD",
 165         [ FILTER_OP_LOAD_FIELD_S8 ] = "LOAD_FIELD_S8",
 166         [ FILTER_OP_LOAD_FIELD_S16 ] = "LOAD_FIELD_S16",
 167         [ FILTER_OP_LOAD_FIELD_S32 ] = "LOAD_FIELD_S32",
 168         [ FILTER_OP_LOAD_FIELD_S64 ] = "LOAD_FIELD_S64",
 169         [ FILTER_OP_LOAD_FIELD_U8 ] = "LOAD_FIELD_U8",
 170         [ FILTER_OP_LOAD_FIELD_U16 ] = "LOAD_FIELD_U16",
 171         [ FILTER_OP_LOAD_FIELD_U32 ] = "LOAD_FIELD_U32",
 172         [ FILTER_OP_LOAD_FIELD_U64 ] = "LOAD_FIELD_U64",
 173         [ FILTER_OP_LOAD_FIELD_STRING ] = "LOAD_FIELD_STRING",
 174         [ FILTER_OP_LOAD_FIELD_SEQUENCE ] = "LOAD_FIELD_SEQUENCE",
 175         [ FILTER_OP_LOAD_FIELD_DOUBLE ] = "LOAD_FIELD_DOUBLE",
 176
 177         [ FILTER_OP_UNARY_BIT_NOT ] = "UNARY_BIT_NOT",
 178
 179         [ FILTER_OP_RETURN_S64 ] = "RETURN_S64",
 180 };
 181
 182 const char *print_op(enum filter_op op)
 183 {
 184         if (op >= NR_FILTER_OPS)
 185                 return "UNKNOWN";
 186         else
 187                 return opnames[op];
 188 }
 189
 190 static
 191 int apply_field_reloc(struct lttng_event *event,
 192                 struct bytecode_runtime *runtime,
 193                 uint32_t runtime_len,
 194                 uint32_t reloc_offset,
 195                 const char *field_name,
 196                 enum filter_op filter_op)
 197 {
 198         const struct lttng_event_desc *desc;
 199         const struct lttng_event_field *fields, *field = NULL;
 200         unsigned int nr_fields, i;
 201         struct load_op *op;
 202         uint32_t field_offset = 0;
 203
 204         dbg_printf("Apply field reloc: %u %s\n", reloc_offset, field_name);
 205
 206         /* Lookup event by name */
 207         desc = event->desc;
 208         if (!desc)
 209                 return -EINVAL;
 210         fields = desc->fields;
 211         if (!fields)
 212                 return -EINVAL;
 213         nr_fields = desc->nr_fields;
 214         for (i = 0; i < nr_fields; i++) {
 215                 if (fields[i].u.ext.nofilter) {
 216                         continue;
 217                 }
 218                 if (!strcmp(fields[i].name, field_name)) {
 219                         field = &fields[i];
 220                         break;
 221                 }
 222                 /* compute field offset */
 223                 switch (fields[i].type.atype) {
 224                 case atype_integer:
 225                 case atype_enum:
 226                 case atype_enum_nestable:
 227                         field_offset += sizeof(int64_t);
 228                         break;
 229                 case atype_array:
 230                 case atype_array_nestable:
 231                 case atype_sequence:
 232                 case atype_sequence_nestable:
 233                         field_offset += sizeof(unsigned long);
 234                         field_offset += sizeof(void *);
 235                         break;
 236                 case atype_string:
 237                         field_offset += sizeof(void *);
 238                         break;
 239                 case atype_float:
 240                         field_offset += sizeof(double);
 241                         break;
 242                 default:
 243                         return -EINVAL;
 244                 }
 245         }
 246         if (!field)
 247                 return -EINVAL;
 248
 249         /* Check if field offset is too large for 16-bit offset */
 250         if (field_offset > FILTER_BYTECODE_MAX_LEN - 1)
 251                 return -EINVAL;
 252
 253         /* set type */
 254         op = (struct load_op *) &runtime->code[reloc_offset];
 255
 256         switch (filter_op) {
 257         case FILTER_OP_LOAD_FIELD_REF:
 258         {
 259                 struct field_ref *field_ref;
 260
 261                 field_ref = (struct field_ref *) op->data;
 262                 switch (field->type.atype) {
 263                 case atype_integer:
 264                 case atype_enum:
 265                 case atype_enum_nestable:
 266                         op->op = FILTER_OP_LOAD_FIELD_REF_S64;
 267                         break;
 268                 case atype_array:
 269                 case atype_array_nestable:
 270                 case atype_sequence:
 271                 case atype_sequence_nestable:
 272                         op->op = FILTER_OP_LOAD_FIELD_REF_SEQUENCE;
 273                         break;
 274                 case atype_string:
 275                         op->op = FILTER_OP_LOAD_FIELD_REF_STRING;
 276                         break;
 277                 case atype_float:
 278                         op->op = FILTER_OP_LOAD_FIELD_REF_DOUBLE;
 279                         break;
 280                 default:
 281                         return -EINVAL;
 282                 }
 283                 /* set offset */
 284                 field_ref->offset = (uint16_t) field_offset;
 285                 break;
 286         }
 287         default:
 288                 return -EINVAL;
 289         }
 290         return 0;
 291 }
 292
 293 static
 294 int apply_context_reloc(struct lttng_event *event,
 295                 struct bytecode_runtime *runtime,
 296                 uint32_t runtime_len,
 297                 uint32_t reloc_offset,
 298                 const char *context_name,
 299                 enum filter_op filter_op)
 300 {
 301         struct load_op *op;
 302         struct lttng_ctx_field *ctx_field;
 303         int idx;
 304         struct lttng_ctx *ctx = *runtime->p.pctx;
 305
 306         dbg_printf("Apply context reloc: %u %s\n", reloc_offset, context_name);
 307
 308         /* Get context index */
 309         idx = lttng_get_context_index(ctx, context_name);
 310         if (idx < 0) {
 311                 if (lttng_context_is_app(context_name)) {
 312                         int ret;
 313
 314                         ret = lttng_ust_add_app_context_to_ctx_rcu(context_name,
 315                                         &ctx);
 316                         if (ret)
 317                                 return ret;
 318                         idx = lttng_get_context_index(ctx, context_name);
 319                         if (idx < 0)
 320                                 return -ENOENT;
 321                 } else {
 322                         return -ENOENT;
 323                 }
 324         }
 325         /* Check if idx is too large for 16-bit offset */
 326         if (idx > FILTER_BYTECODE_MAX_LEN - 1)
 327                 return -EINVAL;
 328
 329         /* Get context return type */
 330         ctx_field = &ctx->fields[idx];
 331         op = (struct load_op *) &runtime->code[reloc_offset];
 332
 333         switch (filter_op) {
 334         case FILTER_OP_GET_CONTEXT_REF:
 335         {
 336                 struct field_ref *field_ref;
 337
 338                 field_ref = (struct field_ref *) op->data;
 339                 switch (ctx_field->event_field.type.atype) {
 340                 case atype_integer:
 341                 case atype_enum:
 342                 case atype_enum_nestable:
 343                         op->op = FILTER_OP_GET_CONTEXT_REF_S64;
 344                         break;
 345                         /* Sequence and array supported as string */
 346                 case atype_string:
 347                 case atype_array:
 348                 case atype_array_nestable:
 349                 case atype_sequence:
 350                 case atype_sequence_nestable:
 351                         op->op = FILTER_OP_GET_CONTEXT_REF_STRING;
 352                         break;
 353                 case atype_float:
 354                         op->op = FILTER_OP_GET_CONTEXT_REF_DOUBLE;
 355                         break;
 356                 case atype_dynamic:
 357                         op->op = FILTER_OP_GET_CONTEXT_REF;
 358                         break;
 359                 default:
 360                         return -EINVAL;
 361                 }
 362                 /* set offset to context index within channel contexts */
 363                 field_ref->offset = (uint16_t) idx;
 364                 break;
 365         }
 366         default:
 367                 return -EINVAL;
 368         }
 369         return 0;
 370 }
 371
 372 static
 373 int apply_reloc(struct lttng_event *event,
 374                 struct bytecode_runtime *runtime,
 375                 uint32_t runtime_len,
 376                 uint32_t reloc_offset,
 377                 const char *name)
 378 {
 379         struct load_op *op;
 380
 381         dbg_printf("Apply reloc: %u %s\n", reloc_offset, name);
 382
 383         /* Ensure that the reloc is within the code */
 384         if (runtime_len - reloc_offset < sizeof(uint16_t))
 385                 return -EINVAL;
 386
 387         op = (struct load_op *) &runtime->code[reloc_offset];
 388         switch (op->op) {
 389         case FILTER_OP_LOAD_FIELD_REF:
 390                 return apply_field_reloc(event, runtime, runtime_len,
 391                         reloc_offset, name, op->op);
 392         case FILTER_OP_GET_CONTEXT_REF:
 393                 return apply_context_reloc(event, runtime, runtime_len,
 394                         reloc_offset, name, op->op);
 395         case FILTER_OP_GET_SYMBOL:
 396         case FILTER_OP_GET_SYMBOL_FIELD:
 397                 /*
 398                  * Will be handled by load specialize phase or
 399                  * dynamically by interpreter.
 400                  */
 401                 return 0;
 402         default:
 403                 ERR("Unknown reloc op type %u\n", op->op);
 404                 return -EINVAL;
 405         }
 406         return 0;
 407 }
 408
 409 static
 410 int bytecode_is_linked(struct lttng_ust_filter_bytecode_node *filter_bytecode,
 411                 struct lttng_event *event)
 412 {
 413         struct lttng_bytecode_runtime *bc_runtime;
 414
 415         cds_list_for_each_entry(bc_runtime,
 416                         &event->bytecode_runtime_head, node) {
 417                 if (bc_runtime->bc == filter_bytecode)
 418                         return 1;
 419         }
 420         return 0;
 421 }
 422
 423 /*
 424  * Take a bytecode with reloc table and link it to an event to create a
 425  * bytecode runtime.
 426  */
 427 static
 428 int _lttng_filter_event_link_bytecode(struct lttng_event *event,
 429                 struct lttng_ust_filter_bytecode_node *filter_bytecode,
 430                 struct cds_list_head *insert_loc)
 431 {
 432         int ret, offset, next_offset;
 433         struct bytecode_runtime *runtime = NULL;
 434         size_t runtime_alloc_len;
 435
 436         if (!filter_bytecode)
 437                 return 0;
 438         /* Bytecode already linked */
 439         if (bytecode_is_linked(filter_bytecode, event))
 440                 return 0;
 441
 442         dbg_printf("Linking...\n");
 443
 444         /* We don't need the reloc table in the runtime */
 445         runtime_alloc_len = sizeof(*runtime) + filter_bytecode->bc.reloc_offset;
 446         runtime = zmalloc(runtime_alloc_len);
 447         if (!runtime) {
 448                 ret = -ENOMEM;
 449                 goto alloc_error;
 450         }
 451         runtime->p.bc = filter_bytecode;
 452         runtime->p.pctx = &event->chan->session->ctx;
 453         runtime->len = filter_bytecode->bc.reloc_offset;
 454         /* copy original bytecode */
 455         memcpy(runtime->code, filter_bytecode->bc.data, runtime->len);
 456         /*
 457          * apply relocs. Those are a uint16_t (offset in bytecode)
 458          * followed by a string (field name).
 459          */
 460         for (offset = filter_bytecode->bc.reloc_offset;
 461                         offset < filter_bytecode->bc.len;
 462                         offset = next_offset) {
 463                 uint16_t reloc_offset =
 464                         *(uint16_t *) &filter_bytecode->bc.data[offset];
 465                 const char *name =
 466                         (const char *) &filter_bytecode->bc.data[offset + sizeof(uint16_t)];
 467
 468                 ret = apply_reloc(event, runtime, runtime->len, reloc_offset, name);
 469                 if (ret) {
 470                         goto link_error;
 471                 }
 472                 next_offset = offset + sizeof(uint16_t) + strlen(name) + 1;
 473         }
 474         /* Validate bytecode */
 475         ret = lttng_filter_validate_bytecode(runtime);
 476         if (ret) {
 477                 goto link_error;
 478         }
 479         /* Specialize bytecode */
 480         ret = lttng_filter_specialize_bytecode(event, runtime);
 481         if (ret) {
 482                 goto link_error;
 483         }
 484         runtime->p.filter = lttng_filter_interpret_bytecode;
 485         runtime->p.link_failed = 0;
 486         cds_list_add_rcu(&runtime->p.node, insert_loc);
 487         dbg_printf("Linking successful.\n");
 488         return 0;
 489
 490 link_error:
 491         runtime->p.filter = lttng_filter_false;
 492         runtime->p.link_failed = 1;
 493         cds_list_add_rcu(&runtime->p.node, insert_loc);
 494 alloc_error:
 495         dbg_printf("Linking failed.\n");
 496         return ret;
 497 }
 498
 499 void lttng_filter_sync_state(struct lttng_bytecode_runtime *runtime)
 500 {
 501         struct lttng_ust_filter_bytecode_node *bc = runtime->bc;
 502
 503         if (!bc->enabler->enabled || runtime->link_failed)
 504                 runtime->filter = lttng_filter_false;
 505         else
 506                 runtime->filter = lttng_filter_interpret_bytecode;
 507 }
 508
 509 /*
 510  * Link bytecode for all enablers referenced by an event.
 511  */
 512 void lttng_event_enabler_link_bytecode(struct lttng_event *event,
 513                 struct lttng_event_enabler *event_enabler)
 514 {
 515         struct lttng_ust_filter_bytecode_node *bc;
 516         struct lttng_bytecode_runtime *runtime;
 517         struct lttng_enabler *base_enabler = lttng_event_enabler_as_enabler(event_enabler);
 518
 519         /* Can only be called for events with desc attached */
 520         assert(event->desc);
 521
 522         /* Link each bytecode. */
 523         cds_list_for_each_entry(bc, &base_enabler->filter_bytecode_head, node) {
 524                 int found = 0, ret;
 525                 struct cds_list_head *insert_loc;
 526
 527                 cds_list_for_each_entry(runtime,
 528                                 &event->bytecode_runtime_head, node) {
 529                         if (runtime->bc == bc) {
 530                                 found = 1;
 531                                 break;
 532                         }
 533                 }
 534                 /* Skip bytecode already linked */
 535                 if (found)
 536                         continue;
 537
 538                 /*
 539                  * Insert at specified priority (seqnum) in increasing
 540                  * order. If there already is a bytecode of the same priority,
 541                  * insert the new bytecode right after it.
 542                  */
 543                 cds_list_for_each_entry_reverse(runtime,
 544                                 &event->bytecode_runtime_head, node) {
 545                         if (runtime->bc->bc.seqnum <= bc->bc.seqnum) {
 546                                 /* insert here */
 547                                 insert_loc = &runtime->node;
 548                                 goto add_within;
 549                         }
 550                 }
 551                 /* Add to head to list */
 552                 insert_loc = &event->bytecode_runtime_head;
 553         add_within:
 554                 dbg_printf("linking bytecode\n");
 555                 ret = _lttng_filter_event_link_bytecode(event, bc,
 556                                 insert_loc);
 557                 if (ret) {
 558                         dbg_printf("[lttng filter] warning: cannot link event bytecode\n");
 559                 }
 560         }
 561 }
 562
 563 /*
 564  * We own the filter_bytecode if we return success.
 565  */
 566 int lttng_filter_enabler_attach_bytecode(struct lttng_enabler *enabler,
 567                 struct lttng_ust_filter_bytecode_node *filter_bytecode)
 568 {
 569         cds_list_add(&filter_bytecode->node, &enabler->filter_bytecode_head);
 570         return 0;
 571 }
 572
 573 static
 574 void free_filter_runtime(struct cds_list_head *bytecode_runtime_head)
 575 {
 576         struct bytecode_runtime *runtime, *tmp;
 577
 578         cds_list_for_each_entry_safe(runtime, tmp, bytecode_runtime_head,
 579                         p.node) {
 580                 free(runtime->data);
 581                 free(runtime);
 582         }
 583 }
 584
 585 void lttng_free_event_filter_runtime(struct lttng_event *event)
 586 {
 587         free_filter_runtime(&event->bytecode_runtime_head);
 588 }