kernel/trace/trace_events_filter.c

   1 /*
   2  * trace_events_filter - generic event filtering
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  *
  18  * Copyright (C) 2009 Tom Zanussi <tzanussi@gmail.com>
  19  */
  20
  21 #include <linux/debugfs.h>
  22 #include <linux/uaccess.h>
  23 #include <linux/module.h>
  24 #include <linux/ctype.h>
  25
  26 #include "trace.h"
  27 #include "trace_output.h"
  28
  29 static int filter_pred_64(struct filter_pred *pred, void *event)
  30 {
  31         u64 *addr = (u64 *)(event + pred->offset);
  32         u64 val = (u64)pred->val;
  33         int match;
  34
  35         match = (val == *addr) ^ pred->not;
  36
  37         return match;
  38 }
  39
  40 static int filter_pred_32(struct filter_pred *pred, void *event)
  41 {
  42         u32 *addr = (u32 *)(event + pred->offset);
  43         u32 val = (u32)pred->val;
  44         int match;
  45
  46         match = (val == *addr) ^ pred->not;
  47
  48         return match;
  49 }
  50
  51 static int filter_pred_16(struct filter_pred *pred, void *event)
  52 {
  53         u16 *addr = (u16 *)(event + pred->offset);
  54         u16 val = (u16)pred->val;
  55         int match;
  56
  57         match = (val == *addr) ^ pred->not;
  58
  59         return match;
  60 }
  61
  62 static int filter_pred_8(struct filter_pred *pred, void *event)
  63 {
  64         u8 *addr = (u8 *)(event + pred->offset);
  65         u8 val = (u8)pred->val;
  66         int match;
  67
  68         match = (val == *addr) ^ pred->not;
  69
  70         return match;
  71 }
  72
  73 static int filter_pred_string(struct filter_pred *pred, void *event)
  74 {
  75         char *addr = (char *)(event + pred->offset);
  76         int cmp, match;
  77
  78         cmp = strncmp(addr, pred->str_val, pred->str_len);
  79
  80         match = (!cmp) ^ pred->not;
  81
  82         return match;
  83 }
  84
  85 /* return 1 if event matches, 0 otherwise (discard) */
  86 int filter_match_preds(struct ftrace_event_call *call, void *rec)
  87 {
  88         int i, matched, and_failed = 0;
  89         struct filter_pred *pred;
  90
  91         for (i = 0; i < MAX_FILTER_PRED; i++) {
  92                 if (call->preds[i]) {
  93                         pred = call->preds[i];
  94                         if (and_failed && !pred->or)
  95                                 continue;
  96                         matched = pred->fn(pred, rec);
  97                         if (!matched && !pred->or) {
  98                                 and_failed = 1;
  99                                 continue;
 100                         } else if (matched && pred->or)
 101                                 return 1;
 102                 } else
 103                         break;
 104         }
 105
 106         if (and_failed)
 107                 return 0;
 108
 109         return 1;
 110 }
 111
 112 void filter_print_preds(struct filter_pred **preds, struct trace_seq *s)
 113 {
 114         char *field_name;
 115         struct filter_pred *pred;
 116         int i;
 117
 118         if (!preds) {
 119                 trace_seq_printf(s, "none\n");
 120                 return;
 121         }
 122
 123         for (i = 0; i < MAX_FILTER_PRED; i++) {
 124                 if (preds[i]) {
 125                         pred = preds[i];
 126                         field_name = pred->field_name;
 127                         if (i)
 128                                 trace_seq_printf(s, pred->or ? "|| " : "&& ");
 129                         trace_seq_printf(s, "%s ", field_name);
 130                         trace_seq_printf(s, pred->not ? "!= " : "== ");
 131                         if (pred->str_val)
 132                                 trace_seq_printf(s, "%s\n", pred->str_val);
 133                         else
 134                                 trace_seq_printf(s, "%llu\n", pred->val);
 135                 } else
 136                         break;
 137         }
 138 }
 139
 140 static struct ftrace_event_field *
 141 find_event_field(struct ftrace_event_call *call, char *name)
 142 {
 143         struct ftrace_event_field *field;
 144
 145         list_for_each_entry(field, &call->fields, link) {
 146                 if (!strcmp(field->name, name))
 147                         return field;
 148         }
 149
 150         return NULL;
 151 }
 152
 153 void filter_free_pred(struct filter_pred *pred)
 154 {
 155         if (!pred)
 156                 return;
 157
 158         kfree(pred->field_name);
 159         kfree(pred->str_val);
 160         kfree(pred);
 161 }
 162
 163 void filter_free_preds(struct ftrace_event_call *call)
 164 {
 165         int i;
 166
 167         if (call->preds) {
 168                 for (i = 0; i < MAX_FILTER_PRED; i++)
 169                         filter_free_pred(call->preds[i]);
 170                 kfree(call->preds);
 171                 call->preds = NULL;
 172         }
 173 }
 174
 175 void filter_free_subsystem_preds(struct event_subsystem *system)
 176 {
 177         struct ftrace_event_call *call = __start_ftrace_events;
 178         int i;
 179
 180         if (system->preds) {
 181                 for (i = 0; i < MAX_FILTER_PRED; i++)
 182                         filter_free_pred(system->preds[i]);
 183                 kfree(system->preds);
 184                 system->preds = NULL;
 185         }
 186
 187         events_for_each(call) {
 188                 if (!call->define_fields)
 189                         continue;
 190
 191                 if (!strcmp(call->system, system->name))
 192                         filter_free_preds(call);
 193         }
 194 }
 195
 196 static int __filter_add_pred(struct ftrace_event_call *call,
 197                              struct filter_pred *pred)
 198 {
 199         int i;
 200
 201         if (call->preds && !pred->compound)
 202                 filter_free_preds(call);
 203
 204         if (!call->preds) {
 205                 call->preds = kzalloc(MAX_FILTER_PRED * sizeof(pred),
 206                                       GFP_KERNEL);
 207                 if (!call->preds)
 208                         return -ENOMEM;
 209         }
 210
 211         for (i = 0; i < MAX_FILTER_PRED; i++) {
 212                 if (!call->preds[i]) {
 213                         call->preds[i] = pred;
 214                         return 0;
 215                 }
 216         }
 217
 218         return -ENOSPC;
 219 }
 220
 221 static int is_string_field(const char *type)
 222 {
 223         if (strchr(type, '[') && strstr(type, "char"))
 224                 return 1;
 225
 226         return 0;
 227 }
 228
 229 int filter_add_pred(struct ftrace_event_call *call, struct filter_pred *pred)
 230 {
 231         struct ftrace_event_field *field;
 232
 233         field = find_event_field(call, pred->field_name);
 234         if (!field)
 235                 return -EINVAL;
 236
 237         pred->offset = field->offset;
 238
 239         if (is_string_field(field->type)) {
 240                 if (!pred->str_val)
 241                         return -EINVAL;
 242                 pred->fn = filter_pred_string;
 243                 pred->str_len = field->size;
 244                 return __filter_add_pred(call, pred);
 245         } else {
 246                 if (pred->str_val)
 247                         return -EINVAL;
 248         }
 249
 250         switch (field->size) {
 251         case 8:
 252                 pred->fn = filter_pred_64;
 253                 break;
 254         case 4:
 255                 pred->fn = filter_pred_32;
 256                 break;
 257         case 2:
 258                 pred->fn = filter_pred_16;
 259                 break;
 260         case 1:
 261                 pred->fn = filter_pred_8;
 262                 break;
 263         default:
 264                 return -EINVAL;
 265         }
 266
 267         return __filter_add_pred(call, pred);
 268 }
 269
 270 static struct filter_pred *copy_pred(struct filter_pred *pred)
 271 {
 272         struct filter_pred *new_pred = kmalloc(sizeof(*pred), GFP_KERNEL);
 273         if (!new_pred)
 274                 return NULL;
 275
 276         memcpy(new_pred, pred, sizeof(*pred));
 277
 278         if (pred->field_name) {
 279                 new_pred->field_name = kstrdup(pred->field_name, GFP_KERNEL);
 280                 if (!new_pred->field_name) {
 281                         kfree(new_pred);
 282                         return NULL;
 283                 }
 284         }
 285
 286         if (pred->str_val) {
 287                 new_pred->str_val = kstrdup(pred->str_val, GFP_KERNEL);
 288                 if (!new_pred->str_val) {
 289                         filter_free_pred(new_pred);
 290                         return NULL;
 291                 }
 292         }
 293
 294         return new_pred;
 295 }
 296
 297 int filter_add_subsystem_pred(struct event_subsystem *system,
 298                               struct filter_pred *pred)
 299 {
 300         struct ftrace_event_call *call = __start_ftrace_events;
 301         struct filter_pred *event_pred;
 302         int i;
 303
 304         if (system->preds && !pred->compound)
 305                 filter_free_subsystem_preds(system);
 306
 307         if (!system->preds) {
 308                 system->preds = kzalloc(MAX_FILTER_PRED * sizeof(pred),
 309                                         GFP_KERNEL);
 310                 if (!system->preds)
 311                         return -ENOMEM;
 312         }
 313
 314         for (i = 0; i < MAX_FILTER_PRED; i++) {
 315                 if (!system->preds[i]) {
 316                         system->preds[i] = pred;
 317                         break;
 318                 }
 319         }
 320
 321         if (i == MAX_FILTER_PRED)
 322                 return -ENOSPC;
 323
 324         events_for_each(call) {
 325                 int err;
 326
 327                 if (!call->define_fields)
 328                         continue;
 329
 330                 if (strcmp(call->system, system->name))
 331                         continue;
 332
 333                 if (!find_event_field(call, pred->field_name))
 334                         continue;
 335
 336                 event_pred = copy_pred(pred);
 337                 if (!event_pred)
 338                         goto oom;
 339
 340                 err = filter_add_pred(call, event_pred);
 341                 if (err)
 342                         filter_free_pred(event_pred);
 343                 if (err == -ENOMEM)
 344                         goto oom;
 345         }
 346
 347         return 0;
 348
 349 oom:
 350         system->preds[i] = NULL;
 351         return -ENOMEM;
 352 }
 353
 354 int filter_parse(char **pbuf, struct filter_pred *pred)
 355 {
 356         char *tmp, *tok, *val_str = NULL;
 357         int tok_n = 0;
 358
 359         /* field ==/!= number, or/and field ==/!= number, number */
 360         while ((tok = strsep(pbuf, " \n"))) {
 361                 if (tok_n == 0) {
 362                         if (!strcmp(tok, "0")) {
 363                                 pred->clear = 1;
 364                                 return 0;
 365                         } else if (!strcmp(tok, "&&")) {
 366                                 pred->or = 0;
 367                                 pred->compound = 1;
 368                         } else if (!strcmp(tok, "||")) {
 369                                 pred->or = 1;
 370                                 pred->compound = 1;
 371                         } else
 372                                 pred->field_name = tok;
 373                         tok_n = 1;
 374                         continue;
 375                 }
 376                 if (tok_n == 1) {
 377                         if (!pred->field_name)
 378                                 pred->field_name = tok;
 379                         else if (!strcmp(tok, "!="))
 380                                 pred->not = 1;
 381                         else if (!strcmp(tok, "=="))
 382                                 pred->not = 0;
 383                         else {
 384                                 pred->field_name = NULL;
 385                                 return -EINVAL;
 386                         }
 387                         tok_n = 2;
 388                         continue;
 389                 }
 390                 if (tok_n == 2) {
 391                         if (pred->compound) {
 392                                 if (!strcmp(tok, "!="))
 393                                         pred->not = 1;
 394                                 else if (!strcmp(tok, "=="))
 395                                         pred->not = 0;
 396                                 else {
 397                                         pred->field_name = NULL;
 398                                         return -EINVAL;
 399                                 }
 400                         } else {
 401                                 val_str = tok;
 402                                 break; /* done */
 403                         }
 404                         tok_n = 3;
 405                         continue;
 406                 }
 407                 if (tok_n == 3) {
 408                         val_str = tok;
 409                         break; /* done */
 410                 }
 411         }
 412
 413         if (!val_str) {
 414                 pred->field_name = NULL;
 415                 return -EINVAL;
 416         }
 417
 418         pred->field_name = kstrdup(pred->field_name, GFP_KERNEL);
 419         if (!pred->field_name)
 420                 return -ENOMEM;
 421
 422         pred->val = simple_strtoull(val_str, &tmp, 0);
 423         if (tmp == val_str) {
 424                 pred->str_val = kstrdup(val_str, GFP_KERNEL);
 425                 if (!pred->str_val)
 426                         return -ENOMEM;
 427         } else if (*tmp != '\0')
 428                 return -EINVAL;
 429
 430         return 0;
 431 }
 432
 433