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_BIT_RSHIFT ] = "BIT_RSHIFT",
  44         [ FILTER_OP_BIT_LSHIFT ] = "BIT_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         [ FILTER_OP_UNARY_BIT_NOT ] = "UNARY_BIT_NOT",
 174 };
 175
 176 const char *lttng_filter_print_op(enum filter_op op)
 177 {
 178         if (op >= NR_FILTER_OPS)
 179                 return "UNKNOWN";
 180         else
 181                 return opnames[op];
 182 }
 183
 184 static
 185 int apply_field_reloc(struct lttng_event *event,
 186                 struct bytecode_runtime *runtime,
 187                 uint32_t runtime_len,
 188                 uint32_t reloc_offset,
 189                 const char *field_name,
 190                 enum filter_op filter_op)
 191 {
 192         const struct lttng_event_desc *desc;
 193         const struct lttng_event_field *fields, *field = NULL;
 194         unsigned int nr_fields, i;
 195         struct load_op *op;
 196         uint32_t field_offset = 0;
 197
 198         dbg_printk("Apply field reloc: %u %s\n", reloc_offset, field_name);
 199
 200         /* Lookup event by name */
 201         desc = event->desc;
 202         if (!desc)
 203                 return -EINVAL;
 204         fields = desc->fields;
 205         if (!fields)
 206                 return -EINVAL;
 207         nr_fields = desc->nr_fields;
 208         for (i = 0; i < nr_fields; i++) {
 209                 if (!strcmp(fields[i].name, field_name)) {
 210                         field = &fields[i];
 211                         break;
 212                 }
 213                 /* compute field offset */
 214                 switch (fields[i].type.atype) {
 215                 case atype_integer:
 216                 case atype_enum:
 217                         field_offset += sizeof(int64_t);
 218                         break;
 219                 case atype_array:
 220                 case atype_sequence:
 221                 case atype_array_bitfield:
 222                 case atype_sequence_bitfield:
 223                         field_offset += sizeof(unsigned long);
 224                         field_offset += sizeof(void *);
 225                         break;
 226                 case atype_string:
 227                         field_offset += sizeof(void *);
 228                         break;
 229                 case atype_struct:              /* Unsupported. */
 230                 case atype_array_compound:      /* Unsupported. */
 231                 case atype_sequence_compound:   /* Unsupported. */
 232                 case atype_variant:             /* Unsupported. */
 233                 default:
 234                         return -EINVAL;
 235                 }
 236         }
 237         if (!field)
 238                 return -EINVAL;
 239
 240         /* Check if field offset is too large for 16-bit offset */
 241         if (field_offset > LTTNG_KERNEL_FILTER_BYTECODE_MAX_LEN - 1)
 242                 return -EINVAL;
 243
 244         /* set type */
 245         op = (struct load_op *) &runtime->code[reloc_offset];
 246
 247         switch (filter_op) {
 248         case FILTER_OP_LOAD_FIELD_REF:
 249         {
 250                 struct field_ref *field_ref;
 251
 252                 field_ref = (struct field_ref *) op->data;
 253                 switch (field->type.atype) {
 254                 case atype_integer:
 255                 case atype_enum:
 256                         op->op = FILTER_OP_LOAD_FIELD_REF_S64;
 257                         break;
 258                 case atype_array:
 259                 case atype_sequence:
 260                         if (field->user)
 261                                 op->op = FILTER_OP_LOAD_FIELD_REF_USER_SEQUENCE;
 262                         else
 263                                 op->op = FILTER_OP_LOAD_FIELD_REF_SEQUENCE;
 264                         break;
 265                 case atype_string:
 266                         if (field->user)
 267                                 op->op = FILTER_OP_LOAD_FIELD_REF_USER_STRING;
 268                         else
 269                                 op->op = FILTER_OP_LOAD_FIELD_REF_STRING;
 270                         break;
 271                 case atype_struct:              /* Unsupported. */
 272                 case atype_array_compound:      /* Unsupported. */
 273                 case atype_sequence_compound:   /* Unsupported. */
 274                 case atype_variant:             /* Unsupported. */
 275                 case atype_array_bitfield:      /* Unsupported. */
 276                 case atype_sequence_bitfield:   /* Unsupported. */
 277                 default:
 278                         return -EINVAL;
 279                 }
 280                 /* set offset */
 281                 field_ref->offset = (uint16_t) field_offset;
 282                 break;
 283         }
 284         default:
 285                 return -EINVAL;
 286         }
 287         return 0;
 288 }
 289
 290 static
 291 int apply_context_reloc(struct lttng_event *event,
 292                 struct bytecode_runtime *runtime,
 293                 uint32_t runtime_len,
 294                 uint32_t reloc_offset,
 295                 const char *context_name,
 296                 enum filter_op filter_op)
 297 {
 298         struct load_op *op;
 299         struct lttng_ctx_field *ctx_field;
 300         int idx;
 301
 302         dbg_printk("Apply context reloc: %u %s\n", reloc_offset, context_name);
 303
 304         /* Get context index */
 305         idx = lttng_get_context_index(lttng_static_ctx, context_name);
 306         if (idx < 0)
 307                 return -ENOENT;
 308
 309         /* Check if idx is too large for 16-bit offset */
 310         if (idx > LTTNG_KERNEL_FILTER_BYTECODE_MAX_LEN - 1)
 311                 return -EINVAL;
 312
 313         /* Get context return type */
 314         ctx_field = &lttng_static_ctx->fields[idx];
 315         op = (struct load_op *) &runtime->code[reloc_offset];
 316
 317         switch (filter_op) {
 318         case FILTER_OP_GET_CONTEXT_REF:
 319         {
 320                 struct field_ref *field_ref;
 321
 322                 field_ref = (struct field_ref *) op->data;
 323                 switch (ctx_field->event_field.type.atype) {
 324                 case atype_integer:
 325                 case atype_enum:
 326                         op->op = FILTER_OP_GET_CONTEXT_REF_S64;
 327                         break;
 328                         /* Sequence and array supported as string */
 329                 case atype_string:
 330                 case atype_array:
 331                 case atype_sequence:
 332                         BUG_ON(ctx_field->event_field.user);
 333                         op->op = FILTER_OP_GET_CONTEXT_REF_STRING;
 334                         break;
 335                 case atype_struct:      /* Unsupported. */
 336                 case atype_array_compound:      /* Unsupported. */
 337                 case atype_sequence_compound:   /* Unsupported. */
 338                 case atype_variant:             /* Unsupported. */
 339                 case atype_array_bitfield:      /* Unsupported. */
 340                 case atype_sequence_bitfield:   /* Unsupported. */
 341                 default:
 342                         return -EINVAL;
 343                 }
 344                 /* set offset to context index within channel contexts */
 345                 field_ref->offset = (uint16_t) idx;
 346                 break;
 347         }
 348         default:
 349                 return -EINVAL;
 350         }
 351         return 0;
 352 }
 353
 354 static
 355 int apply_reloc(struct lttng_event *event,
 356                 struct bytecode_runtime *runtime,
 357                 uint32_t runtime_len,
 358                 uint32_t reloc_offset,
 359                 const char *name)
 360 {
 361         struct load_op *op;
 362
 363         dbg_printk("Apply reloc: %u %s\n", reloc_offset, name);
 364
 365         /* Ensure that the reloc is within the code */
 366         if (runtime_len - reloc_offset < sizeof(uint16_t))
 367                 return -EINVAL;
 368
 369         op = (struct load_op *) &runtime->code[reloc_offset];
 370         switch (op->op) {
 371         case FILTER_OP_LOAD_FIELD_REF:
 372                 return apply_field_reloc(event, runtime, runtime_len,
 373                         reloc_offset, name, op->op);
 374         case FILTER_OP_GET_CONTEXT_REF:
 375                 return apply_context_reloc(event, runtime, runtime_len,
 376                         reloc_offset, name, op->op);
 377         case FILTER_OP_GET_SYMBOL:
 378         case FILTER_OP_GET_SYMBOL_FIELD:
 379                 /*
 380                  * Will be handled by load specialize phase or
 381                  * dynamically by interpreter.
 382                  */
 383                 return 0;
 384         default:
 385                 printk(KERN_WARNING "Unknown reloc op type %u\n", op->op);
 386                 return -EINVAL;
 387         }
 388         return 0;
 389 }
 390
 391 static
 392 int bytecode_is_linked(struct lttng_filter_bytecode_node *filter_bytecode,
 393                 struct lttng_event *event)
 394 {
 395         struct lttng_bytecode_runtime *bc_runtime;
 396
 397         list_for_each_entry(bc_runtime,
 398                         &event->bytecode_runtime_head, node) {
 399                 if (bc_runtime->bc == filter_bytecode)
 400                         return 1;
 401         }
 402         return 0;
 403 }
 404
 405 /*
 406  * Take a bytecode with reloc table and link it to an event to create a
 407  * bytecode runtime.
 408  */
 409 static
 410 int _lttng_filter_event_link_bytecode(struct lttng_event *event,
 411                 struct lttng_filter_bytecode_node *filter_bytecode,
 412                 struct list_head *insert_loc)
 413 {
 414         int ret, offset, next_offset;
 415         struct bytecode_runtime *runtime = NULL;
 416         size_t runtime_alloc_len;
 417
 418         if (!filter_bytecode)
 419                 return 0;
 420         /* Bytecode already linked */
 421         if (bytecode_is_linked(filter_bytecode, event))
 422                 return 0;
 423
 424         dbg_printk("Linking...\n");
 425
 426         /* We don't need the reloc table in the runtime */
 427         runtime_alloc_len = sizeof(*runtime) + filter_bytecode->bc.reloc_offset;
 428         runtime = kzalloc(runtime_alloc_len, GFP_KERNEL);
 429         if (!runtime) {
 430                 ret = -ENOMEM;
 431                 goto alloc_error;
 432         }
 433         runtime->p.bc = filter_bytecode;
 434         runtime->p.event = event;
 435         runtime->len = filter_bytecode->bc.reloc_offset;
 436         /* copy original bytecode */
 437         memcpy(runtime->code, filter_bytecode->bc.data, runtime->len);
 438         /*
 439          * apply relocs. Those are a uint16_t (offset in bytecode)
 440          * followed by a string (field name).
 441          */
 442         for (offset = filter_bytecode->bc.reloc_offset;
 443                         offset < filter_bytecode->bc.len;
 444                         offset = next_offset) {
 445                 uint16_t reloc_offset =
 446                         *(uint16_t *) &filter_bytecode->bc.data[offset];
 447                 const char *name =
 448                         (const char *) &filter_bytecode->bc.data[offset + sizeof(uint16_t)];
 449
 450                 ret = apply_reloc(event, runtime, runtime->len, reloc_offset, name);
 451                 if (ret) {
 452                         goto link_error;
 453                 }
 454                 next_offset = offset + sizeof(uint16_t) + strlen(name) + 1;
 455         }
 456         /* Validate bytecode */
 457         ret = lttng_filter_validate_bytecode(runtime);
 458         if (ret) {
 459                 goto link_error;
 460         }
 461         /* Specialize bytecode */
 462         ret = lttng_filter_specialize_bytecode(event, runtime);
 463         if (ret) {
 464                 goto link_error;
 465         }
 466         runtime->p.filter = lttng_filter_interpret_bytecode;
 467         runtime->p.link_failed = 0;
 468         list_add_rcu(&runtime->p.node, insert_loc);
 469         dbg_printk("Linking successful.\n");
 470         return 0;
 471
 472 link_error:
 473         runtime->p.filter = lttng_filter_false;
 474         runtime->p.link_failed = 1;
 475         list_add_rcu(&runtime->p.node, insert_loc);
 476 alloc_error:
 477         dbg_printk("Linking failed.\n");
 478         return ret;
 479 }
 480
 481 void lttng_filter_sync_state(struct lttng_bytecode_runtime *runtime)
 482 {
 483         struct lttng_filter_bytecode_node *bc = runtime->bc;
 484
 485         if (!bc->enabler->enabled || runtime->link_failed)
 486                 runtime->filter = lttng_filter_false;
 487         else
 488                 runtime->filter = lttng_filter_interpret_bytecode;
 489 }
 490
 491 /*
 492  * Link bytecode for all enablers referenced by an event.
 493  */
 494 void lttng_enabler_event_link_bytecode(struct lttng_event *event,
 495                 struct lttng_enabler *enabler)
 496 {
 497         struct lttng_filter_bytecode_node *bc;
 498         struct lttng_bytecode_runtime *runtime;
 499
 500         /* Can only be called for events with desc attached */
 501         WARN_ON_ONCE(!event->desc);
 502
 503         /* Link each bytecode. */
 504         list_for_each_entry(bc, &enabler->filter_bytecode_head, node) {
 505                 int found = 0, ret;
 506                 struct list_head *insert_loc;
 507
 508                 list_for_each_entry(runtime,
 509                                 &event->bytecode_runtime_head, node) {
 510                         if (runtime->bc == bc) {
 511                                 found = 1;
 512                                 break;
 513                         }
 514                 }
 515                 /* Skip bytecode already linked */
 516                 if (found)
 517                         continue;
 518
 519                 /*
 520                  * Insert at specified priority (seqnum) in increasing
 521                  * order.
 522                  */
 523                 list_for_each_entry_reverse(runtime,
 524                                 &event->bytecode_runtime_head, node) {
 525                         if (runtime->bc->bc.seqnum < bc->bc.seqnum) {
 526                                 /* insert here */
 527                                 insert_loc = &runtime->node;
 528                                 goto add_within;
 529                         }
 530                 }
 531                 /* Add to head to list */
 532                 insert_loc = &event->bytecode_runtime_head;
 533         add_within:
 534                 dbg_printk("linking bytecode\n");
 535                 ret = _lttng_filter_event_link_bytecode(event, bc,
 536                                 insert_loc);
 537                 if (ret) {
 538                         dbg_printk("[lttng filter] warning: cannot link event bytecode\n");
 539                 }
 540         }
 541 }
 542
 543 /*
 544  * We own the filter_bytecode if we return success.
 545  */
 546 int lttng_filter_enabler_attach_bytecode(struct lttng_enabler *enabler,
 547                 struct lttng_filter_bytecode_node *filter_bytecode)
 548 {
 549         list_add(&filter_bytecode->node, &enabler->filter_bytecode_head);
 550         return 0;
 551 }
 552
 553 void lttng_free_enabler_filter_bytecode(struct lttng_enabler *enabler)
 554 {
 555         struct lttng_filter_bytecode_node *filter_bytecode, *tmp;
 556
 557         list_for_each_entry_safe(filter_bytecode, tmp,
 558                         &enabler->filter_bytecode_head, node) {
 559                 kfree(filter_bytecode);
 560         }
 561 }
 562
 563 void lttng_free_event_filter_runtime(struct lttng_event *event)
 564 {
 565         struct bytecode_runtime *runtime, *tmp;
 566
 567         list_for_each_entry_safe(runtime, tmp,
 568                         &event->bytecode_runtime_head, p.node) {
 569                 kfree(runtime->data);
 570                 kfree(runtime);
 571         }
 572 }