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Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
[linux-2.6.git] / kernel / trace / trace_uprobe.c
blobd5d0cd368a5635737f749324b61d1037c361c968
1 /*
2 * uprobes-based tracing events
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 version 2 as
6 * published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License
14 * along with this program; if not, write to the Free Software
15 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
16 *
17 * Copyright (C) IBM Corporation, 2010-2012
18 * Author: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
19 */
20
21 #include <linux/module.h>
22 #include <linux/uaccess.h>
23 #include <linux/uprobes.h>
24 #include <linux/namei.h>
25 #include <linux/string.h>
26
27 #include "trace_probe.h"
28
29 #define UPROBE_EVENT_SYSTEM "uprobes"
30
31 struct uprobe_trace_entry_head {
32 struct trace_entry ent;
33 unsigned long vaddr[];
34 };
35
36 #define SIZEOF_TRACE_ENTRY(is_return) \
37 (sizeof(struct uprobe_trace_entry_head) + \
38 sizeof(unsigned long) * (is_return ? 2 : 1))
39
40 #define DATAOF_TRACE_ENTRY(entry, is_return) \
41 ((void*)(entry) + SIZEOF_TRACE_ENTRY(is_return))
42
43 struct trace_uprobe_filter {
44 rwlock_t rwlock;
45 int nr_systemwide;
46 struct list_head perf_events;
47 };
48
49 /*
50 * uprobe event core functions
51 */
52 struct trace_uprobe {
53 struct list_head list;
54 struct ftrace_event_class class;
55 struct ftrace_event_call call;
56 struct trace_uprobe_filter filter;
57 struct uprobe_consumer consumer;
58 struct inode *inode;
59 char *filename;
60 unsigned long offset;
61 unsigned long nhit;
62 unsigned int flags; /* For TP_FLAG_* */
63 ssize_t size; /* trace entry size */
64 unsigned int nr_args;
65 struct probe_arg args[];
66 };
67
68 #define SIZEOF_TRACE_UPROBE(n) \
69 (offsetof(struct trace_uprobe, args) + \
70 (sizeof(struct probe_arg) * (n)))
71
72 static int register_uprobe_event(struct trace_uprobe *tu);
73 static void unregister_uprobe_event(struct trace_uprobe *tu);
74
75 static DEFINE_MUTEX(uprobe_lock);
76 static LIST_HEAD(uprobe_list);
77
78 static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs);
79 static int uretprobe_dispatcher(struct uprobe_consumer *con,
80 unsigned long func, struct pt_regs *regs);
81
82 static inline void init_trace_uprobe_filter(struct trace_uprobe_filter *filter)
83 {
84 rwlock_init(&filter->rwlock);
85 filter->nr_systemwide = 0;
86 INIT_LIST_HEAD(&filter->perf_events);
87 }
88
89 static inline bool uprobe_filter_is_empty(struct trace_uprobe_filter *filter)
90 {
91 return !filter->nr_systemwide && list_empty(&filter->perf_events);
92 }
93
94 static inline bool is_ret_probe(struct trace_uprobe *tu)
95 {
96 return tu->consumer.ret_handler != NULL;
97 }
98
99 /*
100 * Allocate new trace_uprobe and initialize it (including uprobes).
101 */
102 static struct trace_uprobe *
103 alloc_trace_uprobe(const char *group, const char *event, int nargs, bool is_ret)
104 {
105 struct trace_uprobe *tu;
106
107 if (!event || !is_good_name(event))
108 return ERR_PTR(-EINVAL);
109
110 if (!group || !is_good_name(group))
111 return ERR_PTR(-EINVAL);
112
113 tu = kzalloc(SIZEOF_TRACE_UPROBE(nargs), GFP_KERNEL);
114 if (!tu)
115 return ERR_PTR(-ENOMEM);
116
117 tu->call.class = &tu->class;
118 tu->call.name = kstrdup(event, GFP_KERNEL);
119 if (!tu->call.name)
120 goto error;
121
122 tu->class.system = kstrdup(group, GFP_KERNEL);
123 if (!tu->class.system)
124 goto error;
125
126 INIT_LIST_HEAD(&tu->list);
127 tu->consumer.handler = uprobe_dispatcher;
128 if (is_ret)
129 tu->consumer.ret_handler = uretprobe_dispatcher;
130 init_trace_uprobe_filter(&tu->filter);
131 return tu;
132
133 error:
134 kfree(tu->call.name);
135 kfree(tu);
136
137 return ERR_PTR(-ENOMEM);
138 }
139
140 static void free_trace_uprobe(struct trace_uprobe *tu)
141 {
142 int i;
143
144 for (i = 0; i < tu->nr_args; i++)
145 traceprobe_free_probe_arg(&tu->args[i]);
146
147 iput(tu->inode);
148 kfree(tu->call.class->system);
149 kfree(tu->call.name);
150 kfree(tu->filename);
151 kfree(tu);
152 }
153
154 static struct trace_uprobe *find_probe_event(const char *event, const char *group)
155 {
156 struct trace_uprobe *tu;
157
158 list_for_each_entry(tu, &uprobe_list, list)
159 if (strcmp(tu->call.name, event) == 0 &&
160 strcmp(tu->call.class->system, group) == 0)
161 return tu;
162
163 return NULL;
164 }
165
166 /* Unregister a trace_uprobe and probe_event: call with locking uprobe_lock */
167 static void unregister_trace_uprobe(struct trace_uprobe *tu)
168 {
169 list_del(&tu->list);
170 unregister_uprobe_event(tu);
171 free_trace_uprobe(tu);
172 }
173
174 /* Register a trace_uprobe and probe_event */
175 static int register_trace_uprobe(struct trace_uprobe *tu)
176 {
177 struct trace_uprobe *old_tp;
178 int ret;
179
180 mutex_lock(&uprobe_lock);
181
182 /* register as an event */
183 old_tp = find_probe_event(tu->call.name, tu->call.class->system);
184 if (old_tp)
185 /* delete old event */
186 unregister_trace_uprobe(old_tp);
187
188 ret = register_uprobe_event(tu);
189 if (ret) {
190 pr_warning("Failed to register probe event(%d)\n", ret);
191 goto end;
192 }
193
194 list_add_tail(&tu->list, &uprobe_list);
195
196 end:
197 mutex_unlock(&uprobe_lock);
198
199 return ret;
200 }
201
202 /*
203 * Argument syntax:
204 * - Add uprobe: p|r[:[GRP/]EVENT] PATH:SYMBOL [FETCHARGS]
205 *
206 * - Remove uprobe: -:[GRP/]EVENT
207 */
208 static int create_trace_uprobe(int argc, char **argv)
209 {
210 struct trace_uprobe *tu;
211 struct inode *inode;
212 char *arg, *event, *group, *filename;
213 char buf[MAX_EVENT_NAME_LEN];
214 struct path path;
215 unsigned long offset;
216 bool is_delete, is_return;
217 int i, ret;
218
219 inode = NULL;
220 ret = 0;
221 is_delete = false;
222 is_return = false;
223 event = NULL;
224 group = NULL;
225
226 /* argc must be >= 1 */
227 if (argv[0][0] == '-')
228 is_delete = true;
229 else if (argv[0][0] == 'r')
230 is_return = true;
231 else if (argv[0][0] != 'p') {
232 pr_info("Probe definition must be started with 'p', 'r' or '-'.\n");
233 return -EINVAL;
234 }
235
236 if (argv[0][1] == ':') {
237 event = &argv[0][2];
238 arg = strchr(event, '/');
239
240 if (arg) {
241 group = event;
242 event = arg + 1;
243 event[-1] = '\0';
244
245 if (strlen(group) == 0) {
246 pr_info("Group name is not specified\n");
247 return -EINVAL;
248 }
249 }
250 if (strlen(event) == 0) {
251 pr_info("Event name is not specified\n");
252 return -EINVAL;
253 }
254 }
255 if (!group)
256 group = UPROBE_EVENT_SYSTEM;
257
258 if (is_delete) {
259 if (!event) {
260 pr_info("Delete command needs an event name.\n");
261 return -EINVAL;
262 }
263 mutex_lock(&uprobe_lock);
264 tu = find_probe_event(event, group);
265
266 if (!tu) {
267 mutex_unlock(&uprobe_lock);
268 pr_info("Event %s/%s doesn't exist.\n", group, event);
269 return -ENOENT;
270 }
271 /* delete an event */
272 unregister_trace_uprobe(tu);
273 mutex_unlock(&uprobe_lock);
274 return 0;
275 }
276
277 if (argc < 2) {
278 pr_info("Probe point is not specified.\n");
279 return -EINVAL;
280 }
281 if (isdigit(argv[1][0])) {
282 pr_info("probe point must be have a filename.\n");
283 return -EINVAL;
284 }
285 arg = strchr(argv[1], ':');
286 if (!arg) {
287 ret = -EINVAL;
288 goto fail_address_parse;
289 }
290
291 *arg++ = '\0';
292 filename = argv[1];
293 ret = kern_path(filename, LOOKUP_FOLLOW, &path);
294 if (ret)
295 goto fail_address_parse;
296
297 inode = igrab(path.dentry->d_inode);
298 path_put(&path);
299
300 if (!inode || !S_ISREG(inode->i_mode)) {
301 ret = -EINVAL;
302 goto fail_address_parse;
303 }
304
305 ret = kstrtoul(arg, 0, &offset);
306 if (ret)
307 goto fail_address_parse;
308
309 argc -= 2;
310 argv += 2;
311
312 /* setup a probe */
313 if (!event) {
314 char *tail;
315 char *ptr;
316
317 tail = kstrdup(kbasename(filename), GFP_KERNEL);
318 if (!tail) {
319 ret = -ENOMEM;
320 goto fail_address_parse;
321 }
322
323 ptr = strpbrk(tail, ".-_");
324 if (ptr)
325 *ptr = '\0';
326
327 snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_0x%lx", 'p', tail, offset);
328 event = buf;
329 kfree(tail);
330 }
331
332 tu = alloc_trace_uprobe(group, event, argc, is_return);
333 if (IS_ERR(tu)) {
334 pr_info("Failed to allocate trace_uprobe.(%d)\n", (int)PTR_ERR(tu));
335 ret = PTR_ERR(tu);
336 goto fail_address_parse;
337 }
338 tu->offset = offset;
339 tu->inode = inode;
340 tu->filename = kstrdup(filename, GFP_KERNEL);
341
342 if (!tu->filename) {
343 pr_info("Failed to allocate filename.\n");
344 ret = -ENOMEM;
345 goto error;
346 }
347
348 /* parse arguments */
349 ret = 0;
350 for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
351 /* Increment count for freeing args in error case */
352 tu->nr_args++;
353
354 /* Parse argument name */
355 arg = strchr(argv[i], '=');
356 if (arg) {
357 *arg++ = '\0';
358 tu->args[i].name = kstrdup(argv[i], GFP_KERNEL);
359 } else {
360 arg = argv[i];
361 /* If argument name is omitted, set "argN" */
362 snprintf(buf, MAX_EVENT_NAME_LEN, "arg%d", i + 1);
363 tu->args[i].name = kstrdup(buf, GFP_KERNEL);
364 }
365
366 if (!tu->args[i].name) {
367 pr_info("Failed to allocate argument[%d] name.\n", i);
368 ret = -ENOMEM;
369 goto error;
370 }
371
372 if (!is_good_name(tu->args[i].name)) {
373 pr_info("Invalid argument[%d] name: %s\n", i, tu->args[i].name);
374 ret = -EINVAL;
375 goto error;
376 }
377
378 if (traceprobe_conflict_field_name(tu->args[i].name, tu->args, i)) {
379 pr_info("Argument[%d] name '%s' conflicts with "
380 "another field.\n", i, argv[i]);
381 ret = -EINVAL;
382 goto error;
383 }
384
385 /* Parse fetch argument */
386 ret = traceprobe_parse_probe_arg(arg, &tu->size, &tu->args[i], false, false);
387 if (ret) {
388 pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
389 goto error;
390 }
391 }
392
393 ret = register_trace_uprobe(tu);
394 if (ret)
395 goto error;
396 return 0;
397
398 error:
399 free_trace_uprobe(tu);
400 return ret;
401
402 fail_address_parse:
403 if (inode)
404 iput(inode);
405
406 pr_info("Failed to parse address or file.\n");
407
408 return ret;
409 }
410
411 static void cleanup_all_probes(void)
412 {
413 struct trace_uprobe *tu;
414
415 mutex_lock(&uprobe_lock);
416 while (!list_empty(&uprobe_list)) {
417 tu = list_entry(uprobe_list.next, struct trace_uprobe, list);
418 unregister_trace_uprobe(tu);
419 }
420 mutex_unlock(&uprobe_lock);
421 }
422
423 /* Probes listing interfaces */
424 static void *probes_seq_start(struct seq_file *m, loff_t *pos)
425 {
426 mutex_lock(&uprobe_lock);
427 return seq_list_start(&uprobe_list, *pos);
428 }
429
430 static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
431 {
432 return seq_list_next(v, &uprobe_list, pos);
433 }
434
435 static void probes_seq_stop(struct seq_file *m, void *v)
436 {
437 mutex_unlock(&uprobe_lock);
438 }
439
440 static int probes_seq_show(struct seq_file *m, void *v)
441 {
442 struct trace_uprobe *tu = v;
443 char c = is_ret_probe(tu) ? 'r' : 'p';
444 int i;
445
446 seq_printf(m, "%c:%s/%s", c, tu->call.class->system, tu->call.name);
447 seq_printf(m, " %s:0x%p", tu->filename, (void *)tu->offset);
448
449 for (i = 0; i < tu->nr_args; i++)
450 seq_printf(m, " %s=%s", tu->args[i].name, tu->args[i].comm);
451
452 seq_printf(m, "\n");
453 return 0;
454 }
455
456 static const struct seq_operations probes_seq_op = {
457 .start = probes_seq_start,
458 .next = probes_seq_next,
459 .stop = probes_seq_stop,
460 .show = probes_seq_show
461 };
462
463 static int probes_open(struct inode *inode, struct file *file)
464 {
465 if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC))
466 cleanup_all_probes();
467
468 return seq_open(file, &probes_seq_op);
469 }
470
471 static ssize_t probes_write(struct file *file, const char __user *buffer,
472 size_t count, loff_t *ppos)
473 {
474 return traceprobe_probes_write(file, buffer, count, ppos, create_trace_uprobe);
475 }
476
477 static const struct file_operations uprobe_events_ops = {
478 .owner = THIS_MODULE,
479 .open = probes_open,
480 .read = seq_read,
481 .llseek = seq_lseek,
482 .release = seq_release,
483 .write = probes_write,
484 };
485
486 /* Probes profiling interfaces */
487 static int probes_profile_seq_show(struct seq_file *m, void *v)
488 {
489 struct trace_uprobe *tu = v;
490
491 seq_printf(m, " %s %-44s %15lu\n", tu->filename, tu->call.name, tu->nhit);
492 return 0;
493 }
494
495 static const struct seq_operations profile_seq_op = {
496 .start = probes_seq_start,
497 .next = probes_seq_next,
498 .stop = probes_seq_stop,
499 .show = probes_profile_seq_show
500 };
501
502 static int profile_open(struct inode *inode, struct file *file)
503 {
504 return seq_open(file, &profile_seq_op);
505 }
506
507 static const struct file_operations uprobe_profile_ops = {
508 .owner = THIS_MODULE,
509 .open = profile_open,
510 .read = seq_read,
511 .llseek = seq_lseek,
512 .release = seq_release,
513 };
514
515 static void uprobe_trace_print(struct trace_uprobe *tu,
516 unsigned long func, struct pt_regs *regs)
517 {
518 struct uprobe_trace_entry_head *entry;
519 struct ring_buffer_event *event;
520 struct ring_buffer *buffer;
521 void *data;
522 int size, i;
523 struct ftrace_event_call *call = &tu->call;
524
525 size = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
526 event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
527 size + tu->size, 0, 0);
528 if (!event)
529 return;
530
531 entry = ring_buffer_event_data(event);
532 if (is_ret_probe(tu)) {
533 entry->vaddr[0] = func;
534 entry->vaddr[1] = instruction_pointer(regs);
535 data = DATAOF_TRACE_ENTRY(entry, true);
536 } else {
537 entry->vaddr[0] = instruction_pointer(regs);
538 data = DATAOF_TRACE_ENTRY(entry, false);
539 }
540
541 for (i = 0; i < tu->nr_args; i++)
542 call_fetch(&tu->args[i].fetch, regs, data + tu->args[i].offset);
543
544 if (!filter_current_check_discard(buffer, call, entry, event))
545 trace_buffer_unlock_commit(buffer, event, 0, 0);
546 }
547
548 /* uprobe handler */
549 static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs)
550 {
551 if (!is_ret_probe(tu))
552 uprobe_trace_print(tu, 0, regs);
553 return 0;
554 }
555
556 static void uretprobe_trace_func(struct trace_uprobe *tu, unsigned long func,
557 struct pt_regs *regs)
558 {
559 uprobe_trace_print(tu, func, regs);
560 }
561
562 /* Event entry printers */
563 static enum print_line_t
564 print_uprobe_event(struct trace_iterator *iter, int flags, struct trace_event *event)
565 {
566 struct uprobe_trace_entry_head *entry;
567 struct trace_seq *s = &iter->seq;
568 struct trace_uprobe *tu;
569 u8 *data;
570 int i;
571
572 entry = (struct uprobe_trace_entry_head *)iter->ent;
573 tu = container_of(event, struct trace_uprobe, call.event);
574
575 if (is_ret_probe(tu)) {
576 if (!trace_seq_printf(s, "%s: (0x%lx <- 0x%lx)", tu->call.name,
577 entry->vaddr[1], entry->vaddr[0]))
578 goto partial;
579 data = DATAOF_TRACE_ENTRY(entry, true);
580 } else {
581 if (!trace_seq_printf(s, "%s: (0x%lx)", tu->call.name,
582 entry->vaddr[0]))
583 goto partial;
584 data = DATAOF_TRACE_ENTRY(entry, false);
585 }
586
587 for (i = 0; i < tu->nr_args; i++) {
588 if (!tu->args[i].type->print(s, tu->args[i].name,
589 data + tu->args[i].offset, entry))
590 goto partial;
591 }
592
593 if (trace_seq_puts(s, "\n"))
594 return TRACE_TYPE_HANDLED;
595
596 partial:
597 return TRACE_TYPE_PARTIAL_LINE;
598 }
599
600 static inline bool is_trace_uprobe_enabled(struct trace_uprobe *tu)
601 {
602 return tu->flags & (TP_FLAG_TRACE | TP_FLAG_PROFILE);
603 }
604
605 typedef bool (*filter_func_t)(struct uprobe_consumer *self,
606 enum uprobe_filter_ctx ctx,
607 struct mm_struct *mm);
608
609 static int
610 probe_event_enable(struct trace_uprobe *tu, int flag, filter_func_t filter)
611 {
612 int ret = 0;
613
614 if (is_trace_uprobe_enabled(tu))
615 return -EINTR;
616
617 WARN_ON(!uprobe_filter_is_empty(&tu->filter));
618
619 tu->flags |= flag;
620 tu->consumer.filter = filter;
621 ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
622 if (ret)
623 tu->flags &= ~flag;
624
625 return ret;
626 }
627
628 static void probe_event_disable(struct trace_uprobe *tu, int flag)
629 {
630 if (!is_trace_uprobe_enabled(tu))
631 return;
632
633 WARN_ON(!uprobe_filter_is_empty(&tu->filter));
634
635 uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
636 tu->flags &= ~flag;
637 }
638
639 static int uprobe_event_define_fields(struct ftrace_event_call *event_call)
640 {
641 int ret, i, size;
642 struct uprobe_trace_entry_head field;
643 struct trace_uprobe *tu = event_call->data;
644
645 if (is_ret_probe(tu)) {
646 DEFINE_FIELD(unsigned long, vaddr[0], FIELD_STRING_FUNC, 0);
647 DEFINE_FIELD(unsigned long, vaddr[1], FIELD_STRING_RETIP, 0);
648 size = SIZEOF_TRACE_ENTRY(true);
649 } else {
650 DEFINE_FIELD(unsigned long, vaddr[0], FIELD_STRING_IP, 0);
651 size = SIZEOF_TRACE_ENTRY(false);
652 }
653 /* Set argument names as fields */
654 for (i = 0; i < tu->nr_args; i++) {
655 ret = trace_define_field(event_call, tu->args[i].type->fmttype,
656 tu->args[i].name,
657 size + tu->args[i].offset,
658 tu->args[i].type->size,
659 tu->args[i].type->is_signed,
660 FILTER_OTHER);
661
662 if (ret)
663 return ret;
664 }
665 return 0;
666 }
667
668 #define LEN_OR_ZERO (len ? len - pos : 0)
669 static int __set_print_fmt(struct trace_uprobe *tu, char *buf, int len)
670 {
671 const char *fmt, *arg;
672 int i;
673 int pos = 0;
674
675 if (is_ret_probe(tu)) {
676 fmt = "(%lx <- %lx)";
677 arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
678 } else {
679 fmt = "(%lx)";
680 arg = "REC->" FIELD_STRING_IP;
681 }
682
683 /* When len=0, we just calculate the needed length */
684
685 pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
686
687 for (i = 0; i < tu->nr_args; i++) {
688 pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
689 tu->args[i].name, tu->args[i].type->fmt);
690 }
691
692 pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
693
694 for (i = 0; i < tu->nr_args; i++) {
695 pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
696 tu->args[i].name);
697 }
698
699 return pos; /* return the length of print_fmt */
700 }
701 #undef LEN_OR_ZERO
702
703 static int set_print_fmt(struct trace_uprobe *tu)
704 {
705 char *print_fmt;
706 int len;
707
708 /* First: called with 0 length to calculate the needed length */
709 len = __set_print_fmt(tu, NULL, 0);
710 print_fmt = kmalloc(len + 1, GFP_KERNEL);
711 if (!print_fmt)
712 return -ENOMEM;
713
714 /* Second: actually write the @print_fmt */
715 __set_print_fmt(tu, print_fmt, len + 1);
716 tu->call.print_fmt = print_fmt;
717
718 return 0;
719 }
720
721 #ifdef CONFIG_PERF_EVENTS
722 static bool
723 __uprobe_perf_filter(struct trace_uprobe_filter *filter, struct mm_struct *mm)
724 {
725 struct perf_event *event;
726
727 if (filter->nr_systemwide)
728 return true;
729
730 list_for_each_entry(event, &filter->perf_events, hw.tp_list) {
731 if (event->hw.tp_target->mm == mm)
732 return true;
733 }
734
735 return false;
736 }
737
738 static inline bool
739 uprobe_filter_event(struct trace_uprobe *tu, struct perf_event *event)
740 {
741 return __uprobe_perf_filter(&tu->filter, event->hw.tp_target->mm);
742 }
743
744 static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event)
745 {
746 bool done;
747
748 write_lock(&tu->filter.rwlock);
749 if (event->hw.tp_target) {
750 /*
751 * event->parent != NULL means copy_process(), we can avoid
752 * uprobe_apply(). current->mm must be probed and we can rely
753 * on dup_mmap() which preserves the already installed bp's.
754 *
755 * attr.enable_on_exec means that exec/mmap will install the
756 * breakpoints we need.
757 */
758 done = tu->filter.nr_systemwide ||
759 event->parent || event->attr.enable_on_exec ||
760 uprobe_filter_event(tu, event);
761 list_add(&event->hw.tp_list, &tu->filter.perf_events);
762 } else {
763 done = tu->filter.nr_systemwide;
764 tu->filter.nr_systemwide++;
765 }
766 write_unlock(&tu->filter.rwlock);
767
768 if (!done)
769 uprobe_apply(tu->inode, tu->offset, &tu->consumer, true);
770
771 return 0;
772 }
773
774 static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event)
775 {
776 bool done;
777
778 write_lock(&tu->filter.rwlock);
779 if (event->hw.tp_target) {
780 list_del(&event->hw.tp_list);
781 done = tu->filter.nr_systemwide ||
782 (event->hw.tp_target->flags & PF_EXITING) ||
783 uprobe_filter_event(tu, event);
784 } else {
785 tu->filter.nr_systemwide--;
786 done = tu->filter.nr_systemwide;
787 }
788 write_unlock(&tu->filter.rwlock);
789
790 if (!done)
791 uprobe_apply(tu->inode, tu->offset, &tu->consumer, false);
792
793 return 0;
794 }
795
796 static bool uprobe_perf_filter(struct uprobe_consumer *uc,
797 enum uprobe_filter_ctx ctx, struct mm_struct *mm)
798 {
799 struct trace_uprobe *tu;
800 int ret;
801
802 tu = container_of(uc, struct trace_uprobe, consumer);
803 read_lock(&tu->filter.rwlock);
804 ret = __uprobe_perf_filter(&tu->filter, mm);
805 read_unlock(&tu->filter.rwlock);
806
807 return ret;
808 }
809
810 static void uprobe_perf_print(struct trace_uprobe *tu,
811 unsigned long func, struct pt_regs *regs)
812 {
813 struct ftrace_event_call *call = &tu->call;
814 struct uprobe_trace_entry_head *entry;
815 struct hlist_head *head;
816 void *data;
817 int size, rctx, i;
818
819 size = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
820 size = ALIGN(size + tu->size + sizeof(u32), sizeof(u64)) - sizeof(u32);
821 if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, "profile buffer not large enough"))
822 return;
823
824 preempt_disable();
825 head = this_cpu_ptr(call->perf_events);
826 if (hlist_empty(head))
827 goto out;
828
829 entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
830 if (!entry)
831 goto out;
832
833 if (is_ret_probe(tu)) {
834 entry->vaddr[0] = func;
835 entry->vaddr[1] = instruction_pointer(regs);
836 data = DATAOF_TRACE_ENTRY(entry, true);
837 } else {
838 entry->vaddr[0] = instruction_pointer(regs);
839 data = DATAOF_TRACE_ENTRY(entry, false);
840 }
841
842 for (i = 0; i < tu->nr_args; i++)
843 call_fetch(&tu->args[i].fetch, regs, data + tu->args[i].offset);
844
845 perf_trace_buf_submit(entry, size, rctx, 0, 1, regs, head, NULL);
846 out:
847 preempt_enable();
848 }
849
850 /* uprobe profile handler */
851 static int uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs)
852 {
853 if (!uprobe_perf_filter(&tu->consumer, 0, current->mm))
854 return UPROBE_HANDLER_REMOVE;
855
856 if (!is_ret_probe(tu))
857 uprobe_perf_print(tu, 0, regs);
858 return 0;
859 }
860
861 static void uretprobe_perf_func(struct trace_uprobe *tu, unsigned long func,
862 struct pt_regs *regs)
863 {
864 uprobe_perf_print(tu, func, regs);
865 }
866 #endif /* CONFIG_PERF_EVENTS */
867
868 static
869 int trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg type, void *data)
870 {
871 struct trace_uprobe *tu = event->data;
872
873 switch (type) {
874 case TRACE_REG_REGISTER:
875 return probe_event_enable(tu, TP_FLAG_TRACE, NULL);
876
877 case TRACE_REG_UNREGISTER:
878 probe_event_disable(tu, TP_FLAG_TRACE);
879 return 0;
880
881 #ifdef CONFIG_PERF_EVENTS
882 case TRACE_REG_PERF_REGISTER:
883 return probe_event_enable(tu, TP_FLAG_PROFILE, uprobe_perf_filter);
884
885 case TRACE_REG_PERF_UNREGISTER:
886 probe_event_disable(tu, TP_FLAG_PROFILE);
887 return 0;
888
889 case TRACE_REG_PERF_OPEN:
890 return uprobe_perf_open(tu, data);
891
892 case TRACE_REG_PERF_CLOSE:
893 return uprobe_perf_close(tu, data);
894
895 #endif
896 default:
897 return 0;
898 }
899 return 0;
900 }
901
902 static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs)
903 {
904 struct trace_uprobe *tu;
905 int ret = 0;
906
907 tu = container_of(con, struct trace_uprobe, consumer);
908 tu->nhit++;
909
910 if (tu->flags & TP_FLAG_TRACE)
911 ret |= uprobe_trace_func(tu, regs);
912
913 #ifdef CONFIG_PERF_EVENTS
914 if (tu->flags & TP_FLAG_PROFILE)
915 ret |= uprobe_perf_func(tu, regs);
916 #endif
917 return ret;
918 }
919
920 static int uretprobe_dispatcher(struct uprobe_consumer *con,
921 unsigned long func, struct pt_regs *regs)
922 {
923 struct trace_uprobe *tu;
924
925 tu = container_of(con, struct trace_uprobe, consumer);
926
927 if (tu->flags & TP_FLAG_TRACE)
928 uretprobe_trace_func(tu, func, regs);
929
930 #ifdef CONFIG_PERF_EVENTS
931 if (tu->flags & TP_FLAG_PROFILE)
932 uretprobe_perf_func(tu, func, regs);
933 #endif
934 return 0;
935 }
936
937 static struct trace_event_functions uprobe_funcs = {
938 .trace = print_uprobe_event
939 };
940
941 static int register_uprobe_event(struct trace_uprobe *tu)
942 {
943 struct ftrace_event_call *call = &tu->call;
944 int ret;
945
946 /* Initialize ftrace_event_call */
947 INIT_LIST_HEAD(&call->class->fields);
948 call->event.funcs = &uprobe_funcs;
949 call->class->define_fields = uprobe_event_define_fields;
950
951 if (set_print_fmt(tu) < 0)
952 return -ENOMEM;
953
954 ret = register_ftrace_event(&call->event);
955 if (!ret) {
956 kfree(call->print_fmt);
957 return -ENODEV;
958 }
959 call->flags = 0;
960 call->class->reg = trace_uprobe_register;
961 call->data = tu;
962 ret = trace_add_event_call(call);
963
964 if (ret) {
965 pr_info("Failed to register uprobe event: %s\n", call->name);
966 kfree(call->print_fmt);
967 unregister_ftrace_event(&call->event);
968 }
969
970 return ret;
971 }
972
973 static void unregister_uprobe_event(struct trace_uprobe *tu)
974 {
975 /* tu->event is unregistered in trace_remove_event_call() */
976 trace_remove_event_call(&tu->call);
977 kfree(tu->call.print_fmt);
978 tu->call.print_fmt = NULL;
979 }
980
981 /* Make a trace interface for controling probe points */
982 static __init int init_uprobe_trace(void)
983 {
984 struct dentry *d_tracer;
985
986 d_tracer = tracing_init_dentry();
987 if (!d_tracer)
988 return 0;
989
990 trace_create_file("uprobe_events", 0644, d_tracer,
991 NULL, &uprobe_events_ops);
992 /* Profile interface */
993 trace_create_file("uprobe_profile", 0444, d_tracer,
994 NULL, &uprobe_profile_ops);
995 return 0;
996 }
997
998 fs_initcall(init_uprobe_trace);
Linus' kernel tree