tracing/filters: fix race between filter setting and module unload
[linux-2.6.git] / 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 #include <linux/mutex.h>
26
27 #include "trace.h"
28 #include "trace_output.h"
29
30 enum filter_op_ids
31 {
32         OP_OR,
33         OP_AND,
34         OP_NE,
35         OP_EQ,
36         OP_LT,
37         OP_LE,
38         OP_GT,
39         OP_GE,
40         OP_NONE,
41         OP_OPEN_PAREN,
42 };
43
44 struct filter_op {
45         int id;
46         char *string;
47         int precedence;
48 };
49
50 static struct filter_op filter_ops[] = {
51         { OP_OR, "||", 1 },
52         { OP_AND, "&&", 2 },
53         { OP_NE, "!=", 4 },
54         { OP_EQ, "==", 4 },
55         { OP_LT, "<", 5 },
56         { OP_LE, "<=", 5 },
57         { OP_GT, ">", 5 },
58         { OP_GE, ">=", 5 },
59         { OP_NONE, "OP_NONE", 0 },
60         { OP_OPEN_PAREN, "(", 0 },
61 };
62
63 enum {
64         FILT_ERR_NONE,
65         FILT_ERR_INVALID_OP,
66         FILT_ERR_UNBALANCED_PAREN,
67         FILT_ERR_TOO_MANY_OPERANDS,
68         FILT_ERR_OPERAND_TOO_LONG,
69         FILT_ERR_FIELD_NOT_FOUND,
70         FILT_ERR_ILLEGAL_FIELD_OP,
71         FILT_ERR_ILLEGAL_INTVAL,
72         FILT_ERR_BAD_SUBSYS_FILTER,
73         FILT_ERR_TOO_MANY_PREDS,
74         FILT_ERR_MISSING_FIELD,
75         FILT_ERR_INVALID_FILTER,
76 };
77
78 static char *err_text[] = {
79         "No error",
80         "Invalid operator",
81         "Unbalanced parens",
82         "Too many operands",
83         "Operand too long",
84         "Field not found",
85         "Illegal operation for field type",
86         "Illegal integer value",
87         "Couldn't find or set field in one of a subsystem's events",
88         "Too many terms in predicate expression",
89         "Missing field name and/or value",
90         "Meaningless filter expression",
91 };
92
93 struct opstack_op {
94         int op;
95         struct list_head list;
96 };
97
98 struct postfix_elt {
99         int op;
100         char *operand;
101         struct list_head list;
102 };
103
104 struct filter_parse_state {
105         struct filter_op *ops;
106         struct list_head opstack;
107         struct list_head postfix;
108         int lasterr;
109         int lasterr_pos;
110
111         struct {
112                 char *string;
113                 unsigned int cnt;
114                 unsigned int tail;
115         } infix;
116
117         struct {
118                 char string[MAX_FILTER_STR_VAL];
119                 int pos;
120                 unsigned int tail;
121         } operand;
122 };
123
124 DEFINE_COMPARISON_PRED(s64);
125 DEFINE_COMPARISON_PRED(u64);
126 DEFINE_COMPARISON_PRED(s32);
127 DEFINE_COMPARISON_PRED(u32);
128 DEFINE_COMPARISON_PRED(s16);
129 DEFINE_COMPARISON_PRED(u16);
130 DEFINE_COMPARISON_PRED(s8);
131 DEFINE_COMPARISON_PRED(u8);
132
133 DEFINE_EQUALITY_PRED(64);
134 DEFINE_EQUALITY_PRED(32);
135 DEFINE_EQUALITY_PRED(16);
136 DEFINE_EQUALITY_PRED(8);
137
138 static int filter_pred_and(struct filter_pred *pred __attribute((unused)),
139                            void *event __attribute((unused)),
140                            int val1, int val2)
141 {
142         return val1 && val2;
143 }
144
145 static int filter_pred_or(struct filter_pred *pred __attribute((unused)),
146                           void *event __attribute((unused)),
147                           int val1, int val2)
148 {
149         return val1 || val2;
150 }
151
152 /* Filter predicate for fixed sized arrays of characters */
153 static int filter_pred_string(struct filter_pred *pred, void *event,
154                               int val1, int val2)
155 {
156         char *addr = (char *)(event + pred->offset);
157         int cmp, match;
158
159         cmp = strncmp(addr, pred->str_val, pred->str_len);
160
161         match = (!cmp) ^ pred->not;
162
163         return match;
164 }
165
166 /*
167  * Filter predicate for dynamic sized arrays of characters.
168  * These are implemented through a list of strings at the end
169  * of the entry.
170  * Also each of these strings have a field in the entry which
171  * contains its offset from the beginning of the entry.
172  * We have then first to get this field, dereference it
173  * and add it to the address of the entry, and at last we have
174  * the address of the string.
175  */
176 static int filter_pred_strloc(struct filter_pred *pred, void *event,
177                               int val1, int val2)
178 {
179         unsigned short str_loc = *(unsigned short *)(event + pred->offset);
180         char *addr = (char *)(event + str_loc);
181         int cmp, match;
182
183         cmp = strncmp(addr, pred->str_val, pred->str_len);
184
185         match = (!cmp) ^ pred->not;
186
187         return match;
188 }
189
190 static int filter_pred_none(struct filter_pred *pred, void *event,
191                             int val1, int val2)
192 {
193         return 0;
194 }
195
196 /* return 1 if event matches, 0 otherwise (discard) */
197 int filter_match_preds(struct ftrace_event_call *call, void *rec)
198 {
199         struct event_filter *filter = call->filter;
200         int match, top = 0, val1 = 0, val2 = 0;
201         int stack[MAX_FILTER_PRED];
202         struct filter_pred *pred;
203         int i;
204
205         for (i = 0; i < filter->n_preds; i++) {
206                 pred = filter->preds[i];
207                 if (!pred->pop_n) {
208                         match = pred->fn(pred, rec, val1, val2);
209                         stack[top++] = match;
210                         continue;
211                 }
212                 if (pred->pop_n > top) {
213                         WARN_ON_ONCE(1);
214                         return 0;
215                 }
216                 val1 = stack[--top];
217                 val2 = stack[--top];
218                 match = pred->fn(pred, rec, val1, val2);
219                 stack[top++] = match;
220         }
221
222         return stack[--top];
223 }
224 EXPORT_SYMBOL_GPL(filter_match_preds);
225
226 static void parse_error(struct filter_parse_state *ps, int err, int pos)
227 {
228         ps->lasterr = err;
229         ps->lasterr_pos = pos;
230 }
231
232 static void remove_filter_string(struct event_filter *filter)
233 {
234         kfree(filter->filter_string);
235         filter->filter_string = NULL;
236 }
237
238 static int replace_filter_string(struct event_filter *filter,
239                                  char *filter_string)
240 {
241         kfree(filter->filter_string);
242         filter->filter_string = kstrdup(filter_string, GFP_KERNEL);
243         if (!filter->filter_string)
244                 return -ENOMEM;
245
246         return 0;
247 }
248
249 static int append_filter_string(struct event_filter *filter,
250                                 char *string)
251 {
252         int newlen;
253         char *new_filter_string;
254
255         BUG_ON(!filter->filter_string);
256         newlen = strlen(filter->filter_string) + strlen(string) + 1;
257         new_filter_string = kmalloc(newlen, GFP_KERNEL);
258         if (!new_filter_string)
259                 return -ENOMEM;
260
261         strcpy(new_filter_string, filter->filter_string);
262         strcat(new_filter_string, string);
263         kfree(filter->filter_string);
264         filter->filter_string = new_filter_string;
265
266         return 0;
267 }
268
269 static void append_filter_err(struct filter_parse_state *ps,
270                               struct event_filter *filter)
271 {
272         int pos = ps->lasterr_pos;
273         char *buf, *pbuf;
274
275         buf = (char *)__get_free_page(GFP_TEMPORARY);
276         if (!buf)
277                 return;
278
279         append_filter_string(filter, "\n");
280         memset(buf, ' ', PAGE_SIZE);
281         if (pos > PAGE_SIZE - 128)
282                 pos = 0;
283         buf[pos] = '^';
284         pbuf = &buf[pos] + 1;
285
286         sprintf(pbuf, "\nparse_error: %s\n", err_text[ps->lasterr]);
287         append_filter_string(filter, buf);
288         free_page((unsigned long) buf);
289 }
290
291 void print_event_filter(struct ftrace_event_call *call, struct trace_seq *s)
292 {
293         struct event_filter *filter = call->filter;
294
295         mutex_lock(&event_mutex);
296         if (filter->filter_string)
297                 trace_seq_printf(s, "%s\n", filter->filter_string);
298         else
299                 trace_seq_printf(s, "none\n");
300         mutex_unlock(&event_mutex);
301 }
302
303 void print_subsystem_event_filter(struct event_subsystem *system,
304                                   struct trace_seq *s)
305 {
306         struct event_filter *filter = system->filter;
307
308         mutex_lock(&event_mutex);
309         if (filter->filter_string)
310                 trace_seq_printf(s, "%s\n", filter->filter_string);
311         else
312                 trace_seq_printf(s, "none\n");
313         mutex_unlock(&event_mutex);
314 }
315
316 static struct ftrace_event_field *
317 find_event_field(struct ftrace_event_call *call, char *name)
318 {
319         struct ftrace_event_field *field;
320
321         list_for_each_entry(field, &call->fields, link) {
322                 if (!strcmp(field->name, name))
323                         return field;
324         }
325
326         return NULL;
327 }
328
329 static void filter_free_pred(struct filter_pred *pred)
330 {
331         if (!pred)
332                 return;
333
334         kfree(pred->field_name);
335         kfree(pred);
336 }
337
338 static void filter_clear_pred(struct filter_pred *pred)
339 {
340         kfree(pred->field_name);
341         pred->field_name = NULL;
342         pred->str_len = 0;
343 }
344
345 static int filter_set_pred(struct filter_pred *dest,
346                            struct filter_pred *src,
347                            filter_pred_fn_t fn)
348 {
349         *dest = *src;
350         if (src->field_name) {
351                 dest->field_name = kstrdup(src->field_name, GFP_KERNEL);
352                 if (!dest->field_name)
353                         return -ENOMEM;
354         }
355         dest->fn = fn;
356
357         return 0;
358 }
359
360 static void filter_disable_preds(struct ftrace_event_call *call)
361 {
362         struct event_filter *filter = call->filter;
363         int i;
364
365         call->filter_active = 0;
366         filter->n_preds = 0;
367
368         for (i = 0; i < MAX_FILTER_PRED; i++)
369                 filter->preds[i]->fn = filter_pred_none;
370 }
371
372 void destroy_preds(struct ftrace_event_call *call)
373 {
374         struct event_filter *filter = call->filter;
375         int i;
376
377         for (i = 0; i < MAX_FILTER_PRED; i++) {
378                 if (filter->preds[i])
379                         filter_free_pred(filter->preds[i]);
380         }
381         kfree(filter->preds);
382         kfree(filter->filter_string);
383         kfree(filter);
384         call->filter = NULL;
385 }
386
387 int init_preds(struct ftrace_event_call *call)
388 {
389         struct event_filter *filter;
390         struct filter_pred *pred;
391         int i;
392
393         filter = call->filter = kzalloc(sizeof(*filter), GFP_KERNEL);
394         if (!call->filter)
395                 return -ENOMEM;
396
397         call->filter_active = 0;
398         filter->n_preds = 0;
399
400         filter->preds = kzalloc(MAX_FILTER_PRED * sizeof(pred), GFP_KERNEL);
401         if (!filter->preds)
402                 goto oom;
403
404         for (i = 0; i < MAX_FILTER_PRED; i++) {
405                 pred = kzalloc(sizeof(*pred), GFP_KERNEL);
406                 if (!pred)
407                         goto oom;
408                 pred->fn = filter_pred_none;
409                 filter->preds[i] = pred;
410         }
411
412         return 0;
413
414 oom:
415         destroy_preds(call);
416
417         return -ENOMEM;
418 }
419 EXPORT_SYMBOL_GPL(init_preds);
420
421 static void filter_free_subsystem_preds(struct event_subsystem *system)
422 {
423         struct event_filter *filter = system->filter;
424         struct ftrace_event_call *call;
425         int i;
426
427         if (filter->n_preds) {
428                 for (i = 0; i < filter->n_preds; i++)
429                         filter_free_pred(filter->preds[i]);
430                 kfree(filter->preds);
431                 filter->preds = NULL;
432                 filter->n_preds = 0;
433         }
434
435         list_for_each_entry(call, &ftrace_events, list) {
436                 if (!call->define_fields)
437                         continue;
438
439                 if (!strcmp(call->system, system->name)) {
440                         filter_disable_preds(call);
441                         remove_filter_string(call->filter);
442                 }
443         }
444 }
445
446 static int filter_add_pred_fn(struct filter_parse_state *ps,
447                               struct ftrace_event_call *call,
448                               struct filter_pred *pred,
449                               filter_pred_fn_t fn)
450 {
451         struct event_filter *filter = call->filter;
452         int idx, err;
453
454         if (filter->n_preds == MAX_FILTER_PRED) {
455                 parse_error(ps, FILT_ERR_TOO_MANY_PREDS, 0);
456                 return -ENOSPC;
457         }
458
459         idx = filter->n_preds;
460         filter_clear_pred(filter->preds[idx]);
461         err = filter_set_pred(filter->preds[idx], pred, fn);
462         if (err)
463                 return err;
464
465         filter->n_preds++;
466         call->filter_active = 1;
467
468         return 0;
469 }
470
471 enum {
472         FILTER_STATIC_STRING = 1,
473         FILTER_DYN_STRING
474 };
475
476 static int is_string_field(const char *type)
477 {
478         if (strstr(type, "__data_loc") && strstr(type, "char"))
479                 return FILTER_DYN_STRING;
480
481         if (strchr(type, '[') && strstr(type, "char"))
482                 return FILTER_STATIC_STRING;
483
484         return 0;
485 }
486
487 static int is_legal_op(struct ftrace_event_field *field, int op)
488 {
489         if (is_string_field(field->type) && (op != OP_EQ && op != OP_NE))
490                 return 0;
491
492         return 1;
493 }
494
495 static filter_pred_fn_t select_comparison_fn(int op, int field_size,
496                                              int field_is_signed)
497 {
498         filter_pred_fn_t fn = NULL;
499
500         switch (field_size) {
501         case 8:
502                 if (op == OP_EQ || op == OP_NE)
503                         fn = filter_pred_64;
504                 else if (field_is_signed)
505                         fn = filter_pred_s64;
506                 else
507                         fn = filter_pred_u64;
508                 break;
509         case 4:
510                 if (op == OP_EQ || op == OP_NE)
511                         fn = filter_pred_32;
512                 else if (field_is_signed)
513                         fn = filter_pred_s32;
514                 else
515                         fn = filter_pred_u32;
516                 break;
517         case 2:
518                 if (op == OP_EQ || op == OP_NE)
519                         fn = filter_pred_16;
520                 else if (field_is_signed)
521                         fn = filter_pred_s16;
522                 else
523                         fn = filter_pred_u16;
524                 break;
525         case 1:
526                 if (op == OP_EQ || op == OP_NE)
527                         fn = filter_pred_8;
528                 else if (field_is_signed)
529                         fn = filter_pred_s8;
530                 else
531                         fn = filter_pred_u8;
532                 break;
533         }
534
535         return fn;
536 }
537
538 static int filter_add_pred(struct filter_parse_state *ps,
539                            struct ftrace_event_call *call,
540                            struct filter_pred *pred)
541 {
542         struct ftrace_event_field *field;
543         filter_pred_fn_t fn;
544         unsigned long long val;
545         int string_type;
546         int ret;
547
548         pred->fn = filter_pred_none;
549
550         if (pred->op == OP_AND) {
551                 pred->pop_n = 2;
552                 return filter_add_pred_fn(ps, call, pred, filter_pred_and);
553         } else if (pred->op == OP_OR) {
554                 pred->pop_n = 2;
555                 return filter_add_pred_fn(ps, call, pred, filter_pred_or);
556         }
557
558         field = find_event_field(call, pred->field_name);
559         if (!field) {
560                 parse_error(ps, FILT_ERR_FIELD_NOT_FOUND, 0);
561                 return -EINVAL;
562         }
563
564         pred->offset = field->offset;
565
566         if (!is_legal_op(field, pred->op)) {
567                 parse_error(ps, FILT_ERR_ILLEGAL_FIELD_OP, 0);
568                 return -EINVAL;
569         }
570
571         string_type = is_string_field(field->type);
572         if (string_type) {
573                 if (string_type == FILTER_STATIC_STRING)
574                         fn = filter_pred_string;
575                 else
576                         fn = filter_pred_strloc;
577                 pred->str_len = field->size;
578                 if (pred->op == OP_NE)
579                         pred->not = 1;
580                 return filter_add_pred_fn(ps, call, pred, fn);
581         } else {
582                 if (field->is_signed)
583                         ret = strict_strtoll(pred->str_val, 0, &val);
584                 else
585                         ret = strict_strtoull(pred->str_val, 0, &val);
586                 if (ret) {
587                         parse_error(ps, FILT_ERR_ILLEGAL_INTVAL, 0);
588                         return -EINVAL;
589                 }
590                 pred->val = val;
591         }
592
593         fn = select_comparison_fn(pred->op, field->size, field->is_signed);
594         if (!fn) {
595                 parse_error(ps, FILT_ERR_INVALID_OP, 0);
596                 return -EINVAL;
597         }
598
599         if (pred->op == OP_NE)
600                 pred->not = 1;
601
602         return filter_add_pred_fn(ps, call, pred, fn);
603 }
604
605 static int filter_add_subsystem_pred(struct filter_parse_state *ps,
606                                      struct event_subsystem *system,
607                                      struct filter_pred *pred,
608                                      char *filter_string)
609 {
610         struct event_filter *filter = system->filter;
611         struct ftrace_event_call *call;
612         int err = 0;
613
614         if (!filter->preds) {
615                 filter->preds = kzalloc(MAX_FILTER_PRED * sizeof(pred),
616                                         GFP_KERNEL);
617
618                 if (!filter->preds)
619                         return -ENOMEM;
620         }
621
622         if (filter->n_preds == MAX_FILTER_PRED) {
623                 parse_error(ps, FILT_ERR_TOO_MANY_PREDS, 0);
624                 return -ENOSPC;
625         }
626
627         filter->preds[filter->n_preds] = pred;
628         filter->n_preds++;
629
630         list_for_each_entry(call, &ftrace_events, list) {
631
632                 if (!call->define_fields)
633                         continue;
634
635                 if (strcmp(call->system, system->name))
636                         continue;
637
638                 err = filter_add_pred(ps, call, pred);
639                 if (err) {
640                         filter_free_subsystem_preds(system);
641                         parse_error(ps, FILT_ERR_BAD_SUBSYS_FILTER, 0);
642                         goto out;
643                 }
644                 replace_filter_string(call->filter, filter_string);
645         }
646 out:
647         return err;
648 }
649
650 static void parse_init(struct filter_parse_state *ps,
651                        struct filter_op *ops,
652                        char *infix_string)
653 {
654         memset(ps, '\0', sizeof(*ps));
655
656         ps->infix.string = infix_string;
657         ps->infix.cnt = strlen(infix_string);
658         ps->ops = ops;
659
660         INIT_LIST_HEAD(&ps->opstack);
661         INIT_LIST_HEAD(&ps->postfix);
662 }
663
664 static char infix_next(struct filter_parse_state *ps)
665 {
666         ps->infix.cnt--;
667
668         return ps->infix.string[ps->infix.tail++];
669 }
670
671 static char infix_peek(struct filter_parse_state *ps)
672 {
673         if (ps->infix.tail == strlen(ps->infix.string))
674                 return 0;
675
676         return ps->infix.string[ps->infix.tail];
677 }
678
679 static void infix_advance(struct filter_parse_state *ps)
680 {
681         ps->infix.cnt--;
682         ps->infix.tail++;
683 }
684
685 static inline int is_precedence_lower(struct filter_parse_state *ps,
686                                       int a, int b)
687 {
688         return ps->ops[a].precedence < ps->ops[b].precedence;
689 }
690
691 static inline int is_op_char(struct filter_parse_state *ps, char c)
692 {
693         int i;
694
695         for (i = 0; strcmp(ps->ops[i].string, "OP_NONE"); i++) {
696                 if (ps->ops[i].string[0] == c)
697                         return 1;
698         }
699
700         return 0;
701 }
702
703 static int infix_get_op(struct filter_parse_state *ps, char firstc)
704 {
705         char nextc = infix_peek(ps);
706         char opstr[3];
707         int i;
708
709         opstr[0] = firstc;
710         opstr[1] = nextc;
711         opstr[2] = '\0';
712
713         for (i = 0; strcmp(ps->ops[i].string, "OP_NONE"); i++) {
714                 if (!strcmp(opstr, ps->ops[i].string)) {
715                         infix_advance(ps);
716                         return ps->ops[i].id;
717                 }
718         }
719
720         opstr[1] = '\0';
721
722         for (i = 0; strcmp(ps->ops[i].string, "OP_NONE"); i++) {
723                 if (!strcmp(opstr, ps->ops[i].string))
724                         return ps->ops[i].id;
725         }
726
727         return OP_NONE;
728 }
729
730 static inline void clear_operand_string(struct filter_parse_state *ps)
731 {
732         memset(ps->operand.string, '\0', MAX_FILTER_STR_VAL);
733         ps->operand.tail = 0;
734 }
735
736 static inline int append_operand_char(struct filter_parse_state *ps, char c)
737 {
738         if (ps->operand.tail == MAX_FILTER_STR_VAL - 1)
739                 return -EINVAL;
740
741         ps->operand.string[ps->operand.tail++] = c;
742
743         return 0;
744 }
745
746 static int filter_opstack_push(struct filter_parse_state *ps, int op)
747 {
748         struct opstack_op *opstack_op;
749
750         opstack_op = kmalloc(sizeof(*opstack_op), GFP_KERNEL);
751         if (!opstack_op)
752                 return -ENOMEM;
753
754         opstack_op->op = op;
755         list_add(&opstack_op->list, &ps->opstack);
756
757         return 0;
758 }
759
760 static int filter_opstack_empty(struct filter_parse_state *ps)
761 {
762         return list_empty(&ps->opstack);
763 }
764
765 static int filter_opstack_top(struct filter_parse_state *ps)
766 {
767         struct opstack_op *opstack_op;
768
769         if (filter_opstack_empty(ps))
770                 return OP_NONE;
771
772         opstack_op = list_first_entry(&ps->opstack, struct opstack_op, list);
773
774         return opstack_op->op;
775 }
776
777 static int filter_opstack_pop(struct filter_parse_state *ps)
778 {
779         struct opstack_op *opstack_op;
780         int op;
781
782         if (filter_opstack_empty(ps))
783                 return OP_NONE;
784
785         opstack_op = list_first_entry(&ps->opstack, struct opstack_op, list);
786         op = opstack_op->op;
787         list_del(&opstack_op->list);
788
789         kfree(opstack_op);
790
791         return op;
792 }
793
794 static void filter_opstack_clear(struct filter_parse_state *ps)
795 {
796         while (!filter_opstack_empty(ps))
797                 filter_opstack_pop(ps);
798 }
799
800 static char *curr_operand(struct filter_parse_state *ps)
801 {
802         return ps->operand.string;
803 }
804
805 static int postfix_append_operand(struct filter_parse_state *ps, char *operand)
806 {
807         struct postfix_elt *elt;
808
809         elt = kmalloc(sizeof(*elt), GFP_KERNEL);
810         if (!elt)
811                 return -ENOMEM;
812
813         elt->op = OP_NONE;
814         elt->operand = kstrdup(operand, GFP_KERNEL);
815         if (!elt->operand) {
816                 kfree(elt);
817                 return -ENOMEM;
818         }
819
820         list_add_tail(&elt->list, &ps->postfix);
821
822         return 0;
823 }
824
825 static int postfix_append_op(struct filter_parse_state *ps, int op)
826 {
827         struct postfix_elt *elt;
828
829         elt = kmalloc(sizeof(*elt), GFP_KERNEL);
830         if (!elt)
831                 return -ENOMEM;
832
833         elt->op = op;
834         elt->operand = NULL;
835
836         list_add_tail(&elt->list, &ps->postfix);
837
838         return 0;
839 }
840
841 static void postfix_clear(struct filter_parse_state *ps)
842 {
843         struct postfix_elt *elt;
844
845         while (!list_empty(&ps->postfix)) {
846                 elt = list_first_entry(&ps->postfix, struct postfix_elt, list);
847                 kfree(elt->operand);
848                 list_del(&elt->list);
849         }
850 }
851
852 static int filter_parse(struct filter_parse_state *ps)
853 {
854         int in_string = 0;
855         int op, top_op;
856         char ch;
857
858         while ((ch = infix_next(ps))) {
859                 if (ch == '"') {
860                         in_string ^= 1;
861                         continue;
862                 }
863
864                 if (in_string)
865                         goto parse_operand;
866
867                 if (isspace(ch))
868                         continue;
869
870                 if (is_op_char(ps, ch)) {
871                         op = infix_get_op(ps, ch);
872                         if (op == OP_NONE) {
873                                 parse_error(ps, FILT_ERR_INVALID_OP, 0);
874                                 return -EINVAL;
875                         }
876
877                         if (strlen(curr_operand(ps))) {
878                                 postfix_append_operand(ps, curr_operand(ps));
879                                 clear_operand_string(ps);
880                         }
881
882                         while (!filter_opstack_empty(ps)) {
883                                 top_op = filter_opstack_top(ps);
884                                 if (!is_precedence_lower(ps, top_op, op)) {
885                                         top_op = filter_opstack_pop(ps);
886                                         postfix_append_op(ps, top_op);
887                                         continue;
888                                 }
889                                 break;
890                         }
891
892                         filter_opstack_push(ps, op);
893                         continue;
894                 }
895
896                 if (ch == '(') {
897                         filter_opstack_push(ps, OP_OPEN_PAREN);
898                         continue;
899                 }
900
901                 if (ch == ')') {
902                         if (strlen(curr_operand(ps))) {
903                                 postfix_append_operand(ps, curr_operand(ps));
904                                 clear_operand_string(ps);
905                         }
906
907                         top_op = filter_opstack_pop(ps);
908                         while (top_op != OP_NONE) {
909                                 if (top_op == OP_OPEN_PAREN)
910                                         break;
911                                 postfix_append_op(ps, top_op);
912                                 top_op = filter_opstack_pop(ps);
913                         }
914                         if (top_op == OP_NONE) {
915                                 parse_error(ps, FILT_ERR_UNBALANCED_PAREN, 0);
916                                 return -EINVAL;
917                         }
918                         continue;
919                 }
920 parse_operand:
921                 if (append_operand_char(ps, ch)) {
922                         parse_error(ps, FILT_ERR_OPERAND_TOO_LONG, 0);
923                         return -EINVAL;
924                 }
925         }
926
927         if (strlen(curr_operand(ps)))
928                 postfix_append_operand(ps, curr_operand(ps));
929
930         while (!filter_opstack_empty(ps)) {
931                 top_op = filter_opstack_pop(ps);
932                 if (top_op == OP_NONE)
933                         break;
934                 if (top_op == OP_OPEN_PAREN) {
935                         parse_error(ps, FILT_ERR_UNBALANCED_PAREN, 0);
936                         return -EINVAL;
937                 }
938                 postfix_append_op(ps, top_op);
939         }
940
941         return 0;
942 }
943
944 static struct filter_pred *create_pred(int op, char *operand1, char *operand2)
945 {
946         struct filter_pred *pred;
947
948         pred = kzalloc(sizeof(*pred), GFP_KERNEL);
949         if (!pred)
950                 return NULL;
951
952         pred->field_name = kstrdup(operand1, GFP_KERNEL);
953         if (!pred->field_name) {
954                 kfree(pred);
955                 return NULL;
956         }
957
958         strcpy(pred->str_val, operand2);
959         pred->str_len = strlen(operand2);
960
961         pred->op = op;
962
963         return pred;
964 }
965
966 static struct filter_pred *create_logical_pred(int op)
967 {
968         struct filter_pred *pred;
969
970         pred = kzalloc(sizeof(*pred), GFP_KERNEL);
971         if (!pred)
972                 return NULL;
973
974         pred->op = op;
975
976         return pred;
977 }
978
979 static int check_preds(struct filter_parse_state *ps)
980 {
981         int n_normal_preds = 0, n_logical_preds = 0;
982         struct postfix_elt *elt;
983
984         list_for_each_entry(elt, &ps->postfix, list) {
985                 if (elt->op == OP_NONE)
986                         continue;
987
988                 if (elt->op == OP_AND || elt->op == OP_OR) {
989                         n_logical_preds++;
990                         continue;
991                 }
992                 n_normal_preds++;
993         }
994
995         if (!n_normal_preds || n_logical_preds >= n_normal_preds) {
996                 parse_error(ps, FILT_ERR_INVALID_FILTER, 0);
997                 return -EINVAL;
998         }
999
1000         return 0;
1001 }
1002
1003 static int replace_preds(struct event_subsystem *system,
1004                          struct ftrace_event_call *call,
1005                          struct filter_parse_state *ps,
1006                          char *filter_string)
1007 {
1008         char *operand1 = NULL, *operand2 = NULL;
1009         struct filter_pred *pred;
1010         struct postfix_elt *elt;
1011         int err;
1012
1013         err = check_preds(ps);
1014         if (err)
1015                 return err;
1016
1017         list_for_each_entry(elt, &ps->postfix, list) {
1018                 if (elt->op == OP_NONE) {
1019                         if (!operand1)
1020                                 operand1 = elt->operand;
1021                         else if (!operand2)
1022                                 operand2 = elt->operand;
1023                         else {
1024                                 parse_error(ps, FILT_ERR_TOO_MANY_OPERANDS, 0);
1025                                 return -EINVAL;
1026                         }
1027                         continue;
1028                 }
1029
1030                 if (elt->op == OP_AND || elt->op == OP_OR) {
1031                         pred = create_logical_pred(elt->op);
1032                         if (call) {
1033                                 err = filter_add_pred(ps, call, pred);
1034                                 filter_free_pred(pred);
1035                         } else
1036                                 err = filter_add_subsystem_pred(ps, system,
1037                                                         pred, filter_string);
1038                         if (err)
1039                                 return err;
1040
1041                         operand1 = operand2 = NULL;
1042                         continue;
1043                 }
1044
1045                 if (!operand1 || !operand2) {
1046                         parse_error(ps, FILT_ERR_MISSING_FIELD, 0);
1047                         return -EINVAL;
1048                 }
1049
1050                 pred = create_pred(elt->op, operand1, operand2);
1051                 if (call) {
1052                         err = filter_add_pred(ps, call, pred);
1053                         filter_free_pred(pred);
1054                 } else
1055                         err = filter_add_subsystem_pred(ps, system, pred,
1056                                                         filter_string);
1057                 if (err)
1058                         return err;
1059
1060                 operand1 = operand2 = NULL;
1061         }
1062
1063         return 0;
1064 }
1065
1066 int apply_event_filter(struct ftrace_event_call *call, char *filter_string)
1067 {
1068         int err;
1069
1070         struct filter_parse_state *ps;
1071
1072         mutex_lock(&event_mutex);
1073
1074         if (!strcmp(strstrip(filter_string), "0")) {
1075                 filter_disable_preds(call);
1076                 remove_filter_string(call->filter);
1077                 mutex_unlock(&event_mutex);
1078                 return 0;
1079         }
1080
1081         err = -ENOMEM;
1082         ps = kzalloc(sizeof(*ps), GFP_KERNEL);
1083         if (!ps)
1084                 goto out_unlock;
1085
1086         filter_disable_preds(call);
1087         replace_filter_string(call->filter, filter_string);
1088
1089         parse_init(ps, filter_ops, filter_string);
1090         err = filter_parse(ps);
1091         if (err) {
1092                 append_filter_err(ps, call->filter);
1093                 goto out;
1094         }
1095
1096         err = replace_preds(NULL, call, ps, filter_string);
1097         if (err)
1098                 append_filter_err(ps, call->filter);
1099
1100 out:
1101         filter_opstack_clear(ps);
1102         postfix_clear(ps);
1103         kfree(ps);
1104 out_unlock:
1105         mutex_unlock(&event_mutex);
1106
1107         return err;
1108 }
1109
1110 int apply_subsystem_event_filter(struct event_subsystem *system,
1111                                  char *filter_string)
1112 {
1113         int err;
1114
1115         struct filter_parse_state *ps;
1116
1117         mutex_lock(&event_mutex);
1118
1119         if (!strcmp(strstrip(filter_string), "0")) {
1120                 filter_free_subsystem_preds(system);
1121                 remove_filter_string(system->filter);
1122                 mutex_unlock(&event_mutex);
1123                 return 0;
1124         }
1125
1126         err = -ENOMEM;
1127         ps = kzalloc(sizeof(*ps), GFP_KERNEL);
1128         if (!ps)
1129                 goto out_unlock;
1130
1131         filter_free_subsystem_preds(system);
1132         replace_filter_string(system->filter, filter_string);
1133
1134         parse_init(ps, filter_ops, filter_string);
1135         err = filter_parse(ps);
1136         if (err) {
1137                 append_filter_err(ps, system->filter);
1138                 goto out;
1139         }
1140
1141         err = replace_preds(system, NULL, ps, filter_string);
1142         if (err)
1143                 append_filter_err(ps, system->filter);
1144
1145 out:
1146         filter_opstack_clear(ps);
1147         postfix_clear(ps);
1148         kfree(ps);
1149 out_unlock:
1150         mutex_unlock(&event_mutex);
1151
1152         return err;
1153 }
1154