lttng-filter.c

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