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Merge tag 'sound-3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound
[linux-2.6.git] / kernel / trace / trace_uprobe.c
blob32494fb0ee640eef4548ac380cd158eab7415083
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 goto fail_address_parse;
288
289 *arg++ = '\0';
290 filename = argv[1];
291 ret = kern_path(filename, LOOKUP_FOLLOW, &path);
292 if (ret)
293 goto fail_address_parse;
294
295 inode = igrab(path.dentry->d_inode);
296 path_put(&path);
297
298 if (!inode || !S_ISREG(inode->i_mode)) {
299 ret = -EINVAL;
300 goto fail_address_parse;
301 }
302
303 ret = kstrtoul(arg, 0, &offset);
304 if (ret)
305 goto fail_address_parse;
306
307 argc -= 2;
308 argv += 2;
309
310 /* setup a probe */
311 if (!event) {
312 char *tail;
313 char *ptr;
314
315 tail = kstrdup(kbasename(filename), GFP_KERNEL);
316 if (!tail) {
317 ret = -ENOMEM;
318 goto fail_address_parse;
319 }
320
321 ptr = strpbrk(tail, ".-_");
322 if (ptr)
323 *ptr = '\0';
324
325 snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_0x%lx", 'p', tail, offset);
326 event = buf;
327 kfree(tail);
328 }
329
330 tu = alloc_trace_uprobe(group, event, argc, is_return);
331 if (IS_ERR(tu)) {
332 pr_info("Failed to allocate trace_uprobe.(%d)\n", (int)PTR_ERR(tu));
333 ret = PTR_ERR(tu);
334 goto fail_address_parse;
335 }
336 tu->offset = offset;
337 tu->inode = inode;
338 tu->filename = kstrdup(filename, GFP_KERNEL);
339
340 if (!tu->filename) {
341 pr_info("Failed to allocate filename.\n");
342 ret = -ENOMEM;
343 goto error;
344 }
345
346 /* parse arguments */
347 ret = 0;
348 for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
349 /* Increment count for freeing args in error case */
350 tu->nr_args++;
351
352 /* Parse argument name */
353 arg = strchr(argv[i], '=');
354 if (arg) {
355 *arg++ = '\0';
356 tu->args[i].name = kstrdup(argv[i], GFP_KERNEL);
357 } else {
358 arg = argv[i];
359 /* If argument name is omitted, set "argN" */
360 snprintf(buf, MAX_EVENT_NAME_LEN, "arg%d", i + 1);
361 tu->args[i].name = kstrdup(buf, GFP_KERNEL);
362 }
363
364 if (!tu->args[i].name) {
365 pr_info("Failed to allocate argument[%d] name.\n", i);
366 ret = -ENOMEM;
367 goto error;
368 }
369
370 if (!is_good_name(tu->args[i].name)) {
371 pr_info("Invalid argument[%d] name: %s\n", i, tu->args[i].name);
372 ret = -EINVAL;
373 goto error;
374 }
375
376 if (traceprobe_conflict_field_name(tu->args[i].name, tu->args, i)) {
377 pr_info("Argument[%d] name '%s' conflicts with "
378 "another field.\n", i, argv[i]);
379 ret = -EINVAL;
380 goto error;
381 }
382
383 /* Parse fetch argument */
384 ret = traceprobe_parse_probe_arg(arg, &tu->size, &tu->args[i], false, false);
385 if (ret) {
386 pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
387 goto error;
388 }
389 }
390
391 ret = register_trace_uprobe(tu);
392 if (ret)
393 goto error;
394 return 0;
395
396 error:
397 free_trace_uprobe(tu);
398 return ret;
399
400 fail_address_parse:
401 if (inode)
402 iput(inode);
403
404 pr_info("Failed to parse address or file.\n");
405
406 return ret;
407 }
408
409 static void cleanup_all_probes(void)
410 {
411 struct trace_uprobe *tu;
412
413 mutex_lock(&uprobe_lock);
414 while (!list_empty(&uprobe_list)) {
415 tu = list_entry(uprobe_list.next, struct trace_uprobe, list);
416 unregister_trace_uprobe(tu);
417 }
418 mutex_unlock(&uprobe_lock);
419 }
420
421 /* Probes listing interfaces */
422 static void *probes_seq_start(struct seq_file *m, loff_t *pos)
423 {
424 mutex_lock(&uprobe_lock);
425 return seq_list_start(&uprobe_list, *pos);
426 }
427
428 static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
429 {
430 return seq_list_next(v, &uprobe_list, pos);
431 }
432
433 static void probes_seq_stop(struct seq_file *m, void *v)
434 {
435 mutex_unlock(&uprobe_lock);
436 }
437
438 static int probes_seq_show(struct seq_file *m, void *v)
439 {
440 struct trace_uprobe *tu = v;
441 char c = is_ret_probe(tu) ? 'r' : 'p';
442 int i;
443
444 seq_printf(m, "%c:%s/%s", c, tu->call.class->system, tu->call.name);
445 seq_printf(m, " %s:0x%p", tu->filename, (void *)tu->offset);
446
447 for (i = 0; i < tu->nr_args; i++)
448 seq_printf(m, " %s=%s", tu->args[i].name, tu->args[i].comm);
449
450 seq_printf(m, "\n");
451 return 0;
452 }
453
454 static const struct seq_operations probes_seq_op = {
455 .start = probes_seq_start,
456 .next = probes_seq_next,
457 .stop = probes_seq_stop,
458 .show = probes_seq_show
459 };
460
461 static int probes_open(struct inode *inode, struct file *file)
462 {
463 if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC))
464 cleanup_all_probes();
465
466 return seq_open(file, &probes_seq_op);
467 }
468
469 static ssize_t probes_write(struct file *file, const char __user *buffer,
470 size_t count, loff_t *ppos)
471 {
472 return traceprobe_probes_write(file, buffer, count, ppos, create_trace_uprobe);
473 }
474
475 static const struct file_operations uprobe_events_ops = {
476 .owner = THIS_MODULE,
477 .open = probes_open,
478 .read = seq_read,
479 .llseek = seq_lseek,
480 .release = seq_release,
481 .write = probes_write,
482 };
483
484 /* Probes profiling interfaces */
485 static int probes_profile_seq_show(struct seq_file *m, void *v)
486 {
487 struct trace_uprobe *tu = v;
488
489 seq_printf(m, " %s %-44s %15lu\n", tu->filename, tu->call.name, tu->nhit);
490 return 0;
491 }
492
493 static const struct seq_operations profile_seq_op = {
494 .start = probes_seq_start,
495 .next = probes_seq_next,
496 .stop = probes_seq_stop,
497 .show = probes_profile_seq_show
498 };
499
500 static int profile_open(struct inode *inode, struct file *file)
501 {
502 return seq_open(file, &profile_seq_op);
503 }
504
505 static const struct file_operations uprobe_profile_ops = {
506 .owner = THIS_MODULE,
507 .open = profile_open,
508 .read = seq_read,
509 .llseek = seq_lseek,
510 .release = seq_release,
511 };
512
513 static void uprobe_trace_print(struct trace_uprobe *tu,
514 unsigned long func, struct pt_regs *regs)
515 {
516 struct uprobe_trace_entry_head *entry;
517 struct ring_buffer_event *event;
518 struct ring_buffer *buffer;
519 void *data;
520 int size, i;
521 struct ftrace_event_call *call = &tu->call;
522
523 size = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
524 event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
525 size + tu->size, 0, 0);
526 if (!event)
527 return;
528
529 entry = ring_buffer_event_data(event);
530 if (is_ret_probe(tu)) {
531 entry->vaddr[0] = func;
532 entry->vaddr[1] = instruction_pointer(regs);
533 data = DATAOF_TRACE_ENTRY(entry, true);
534 } else {
535 entry->vaddr[0] = instruction_pointer(regs);
536 data = DATAOF_TRACE_ENTRY(entry, false);
537 }
538
539 for (i = 0; i < tu->nr_args; i++)
540 call_fetch(&tu->args[i].fetch, regs, data + tu->args[i].offset);
541
542 if (!filter_current_check_discard(buffer, call, entry, event))
543 trace_buffer_unlock_commit(buffer, event, 0, 0);
544 }
545
546 /* uprobe handler */
547 static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs)
548 {
549 if (!is_ret_probe(tu))
550 uprobe_trace_print(tu, 0, regs);
551 return 0;
552 }
553
554 static void uretprobe_trace_func(struct trace_uprobe *tu, unsigned long func,
555 struct pt_regs *regs)
556 {
557 uprobe_trace_print(tu, func, regs);
558 }
559
560 /* Event entry printers */
561 static enum print_line_t
562 print_uprobe_event(struct trace_iterator *iter, int flags, struct trace_event *event)
563 {
564 struct uprobe_trace_entry_head *entry;
565 struct trace_seq *s = &iter->seq;
566 struct trace_uprobe *tu;
567 u8 *data;
568 int i;
569
570 entry = (struct uprobe_trace_entry_head *)iter->ent;
571 tu = container_of(event, struct trace_uprobe, call.event);
572
573 if (is_ret_probe(tu)) {
574 if (!trace_seq_printf(s, "%s: (0x%lx <- 0x%lx)", tu->call.name,
575 entry->vaddr[1], entry->vaddr[0]))
576 goto partial;
577 data = DATAOF_TRACE_ENTRY(entry, true);
578 } else {
579 if (!trace_seq_printf(s, "%s: (0x%lx)", tu->call.name,
580 entry->vaddr[0]))
581 goto partial;
582 data = DATAOF_TRACE_ENTRY(entry, false);
583 }
584
585 for (i = 0; i < tu->nr_args; i++) {
586 if (!tu->args[i].type->print(s, tu->args[i].name,
587 data + tu->args[i].offset, entry))
588 goto partial;
589 }
590
591 if (trace_seq_puts(s, "\n"))
592 return TRACE_TYPE_HANDLED;
593
594 partial:
595 return TRACE_TYPE_PARTIAL_LINE;
596 }
597
598 static inline bool is_trace_uprobe_enabled(struct trace_uprobe *tu)
599 {
600 return tu->flags & (TP_FLAG_TRACE | TP_FLAG_PROFILE);
601 }
602
603 typedef bool (*filter_func_t)(struct uprobe_consumer *self,
604 enum uprobe_filter_ctx ctx,
605 struct mm_struct *mm);
606
607 static int
608 probe_event_enable(struct trace_uprobe *tu, int flag, filter_func_t filter)
609 {
610 int ret = 0;
611
612 if (is_trace_uprobe_enabled(tu))
613 return -EINTR;
614
615 WARN_ON(!uprobe_filter_is_empty(&tu->filter));
616
617 tu->flags |= flag;
618 tu->consumer.filter = filter;
619 ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
620 if (ret)
621 tu->flags &= ~flag;
622
623 return ret;
624 }
625
626 static void probe_event_disable(struct trace_uprobe *tu, int flag)
627 {
628 if (!is_trace_uprobe_enabled(tu))
629 return;
630
631 WARN_ON(!uprobe_filter_is_empty(&tu->filter));
632
633 uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
634 tu->flags &= ~flag;
635 }
636
637 static int uprobe_event_define_fields(struct ftrace_event_call *event_call)
638 {
639 int ret, i, size;
640 struct uprobe_trace_entry_head field;
641 struct trace_uprobe *tu = event_call->data;
642
643 if (is_ret_probe(tu)) {
644 DEFINE_FIELD(unsigned long, vaddr[0], FIELD_STRING_FUNC, 0);
645 DEFINE_FIELD(unsigned long, vaddr[1], FIELD_STRING_RETIP, 0);
646 size = SIZEOF_TRACE_ENTRY(true);
647 } else {
648 DEFINE_FIELD(unsigned long, vaddr[0], FIELD_STRING_IP, 0);
649 size = SIZEOF_TRACE_ENTRY(false);
650 }
651 /* Set argument names as fields */
652 for (i = 0; i < tu->nr_args; i++) {
653 ret = trace_define_field(event_call, tu->args[i].type->fmttype,
654 tu->args[i].name,
655 size + tu->args[i].offset,
656 tu->args[i].type->size,
657 tu->args[i].type->is_signed,
658 FILTER_OTHER);
659
660 if (ret)
661 return ret;
662 }
663 return 0;
664 }
665
666 #define LEN_OR_ZERO (len ? len - pos : 0)
667 static int __set_print_fmt(struct trace_uprobe *tu, char *buf, int len)
668 {
669 const char *fmt, *arg;
670 int i;
671 int pos = 0;
672
673 if (is_ret_probe(tu)) {
674 fmt = "(%lx <- %lx)";
675 arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
676 } else {
677 fmt = "(%lx)";
678 arg = "REC->" FIELD_STRING_IP;
679 }
680
681 /* When len=0, we just calculate the needed length */
682
683 pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
684
685 for (i = 0; i < tu->nr_args; i++) {
686 pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
687 tu->args[i].name, tu->args[i].type->fmt);
688 }
689
690 pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
691
692 for (i = 0; i < tu->nr_args; i++) {
693 pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
694 tu->args[i].name);
695 }
696
697 return pos; /* return the length of print_fmt */
698 }
699 #undef LEN_OR_ZERO
700
701 static int set_print_fmt(struct trace_uprobe *tu)
702 {
703 char *print_fmt;
704 int len;
705
706 /* First: called with 0 length to calculate the needed length */
707 len = __set_print_fmt(tu, NULL, 0);
708 print_fmt = kmalloc(len + 1, GFP_KERNEL);
709 if (!print_fmt)
710 return -ENOMEM;
711
712 /* Second: actually write the @print_fmt */
713 __set_print_fmt(tu, print_fmt, len + 1);
714 tu->call.print_fmt = print_fmt;
715
716 return 0;
717 }
718
719 #ifdef CONFIG_PERF_EVENTS
720 static bool
721 __uprobe_perf_filter(struct trace_uprobe_filter *filter, struct mm_struct *mm)
722 {
723 struct perf_event *event;
724
725 if (filter->nr_systemwide)
726 return true;
727
728 list_for_each_entry(event, &filter->perf_events, hw.tp_list) {
729 if (event->hw.tp_target->mm == mm)
730 return true;
731 }
732
733 return false;
734 }
735
736 static inline bool
737 uprobe_filter_event(struct trace_uprobe *tu, struct perf_event *event)
738 {
739 return __uprobe_perf_filter(&tu->filter, event->hw.tp_target->mm);
740 }
741
742 static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event)
743 {
744 bool done;
745
746 write_lock(&tu->filter.rwlock);
747 if (event->hw.tp_target) {
748 /*
749 * event->parent != NULL means copy_process(), we can avoid
750 * uprobe_apply(). current->mm must be probed and we can rely
751 * on dup_mmap() which preserves the already installed bp's.
752 *
753 * attr.enable_on_exec means that exec/mmap will install the
754 * breakpoints we need.
755 */
756 done = tu->filter.nr_systemwide ||
757 event->parent || event->attr.enable_on_exec ||
758 uprobe_filter_event(tu, event);
759 list_add(&event->hw.tp_list, &tu->filter.perf_events);
760 } else {
761 done = tu->filter.nr_systemwide;
762 tu->filter.nr_systemwide++;
763 }
764 write_unlock(&tu->filter.rwlock);
765
766 if (!done)
767 uprobe_apply(tu->inode, tu->offset, &tu->consumer, true);
768
769 return 0;
770 }
771
772 static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event)
773 {
774 bool done;
775
776 write_lock(&tu->filter.rwlock);
777 if (event->hw.tp_target) {
778 list_del(&event->hw.tp_list);
779 done = tu->filter.nr_systemwide ||
780 (event->hw.tp_target->flags & PF_EXITING) ||
781 uprobe_filter_event(tu, event);
782 } else {
783 tu->filter.nr_systemwide--;
784 done = tu->filter.nr_systemwide;
785 }
786 write_unlock(&tu->filter.rwlock);
787
788 if (!done)
789 uprobe_apply(tu->inode, tu->offset, &tu->consumer, false);
790
791 return 0;
792 }
793
794 static bool uprobe_perf_filter(struct uprobe_consumer *uc,
795 enum uprobe_filter_ctx ctx, struct mm_struct *mm)
796 {
797 struct trace_uprobe *tu;
798 int ret;
799
800 tu = container_of(uc, struct trace_uprobe, consumer);
801 read_lock(&tu->filter.rwlock);
802 ret = __uprobe_perf_filter(&tu->filter, mm);
803 read_unlock(&tu->filter.rwlock);
804
805 return ret;
806 }
807
808 static void uprobe_perf_print(struct trace_uprobe *tu,
809 unsigned long func, struct pt_regs *regs)
810 {
811 struct ftrace_event_call *call = &tu->call;
812 struct uprobe_trace_entry_head *entry;
813 struct hlist_head *head;
814 void *data;
815 int size, rctx, i;
816
817 size = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
818 size = ALIGN(size + tu->size + sizeof(u32), sizeof(u64)) - sizeof(u32);
819 if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, "profile buffer not large enough"))
820 return;
821
822 preempt_disable();
823 head = this_cpu_ptr(call->perf_events);
824 if (hlist_empty(head))
825 goto out;
826
827 entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
828 if (!entry)
829 goto out;
830
831 if (is_ret_probe(tu)) {
832 entry->vaddr[0] = func;
833 entry->vaddr[1] = instruction_pointer(regs);
834 data = DATAOF_TRACE_ENTRY(entry, true);
835 } else {
836 entry->vaddr[0] = instruction_pointer(regs);
837 data = DATAOF_TRACE_ENTRY(entry, false);
838 }
839
840 for (i = 0; i < tu->nr_args; i++)
841 call_fetch(&tu->args[i].fetch, regs, data + tu->args[i].offset);
842
843 perf_trace_buf_submit(entry, size, rctx, 0, 1, regs, head, NULL);
844 out:
845 preempt_enable();
846 }
847
848 /* uprobe profile handler */
849 static int uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs)
850 {
851 if (!uprobe_perf_filter(&tu->consumer, 0, current->mm))
852 return UPROBE_HANDLER_REMOVE;
853
854 if (!is_ret_probe(tu))
855 uprobe_perf_print(tu, 0, regs);
856 return 0;
857 }
858
859 static void uretprobe_perf_func(struct trace_uprobe *tu, unsigned long func,
860 struct pt_regs *regs)
861 {
862 uprobe_perf_print(tu, func, regs);
863 }
864 #endif /* CONFIG_PERF_EVENTS */
865
866 static
867 int trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg type, void *data)
868 {
869 struct trace_uprobe *tu = event->data;
870
871 switch (type) {
872 case TRACE_REG_REGISTER:
873 return probe_event_enable(tu, TP_FLAG_TRACE, NULL);
874
875 case TRACE_REG_UNREGISTER:
876 probe_event_disable(tu, TP_FLAG_TRACE);
877 return 0;
878
879 #ifdef CONFIG_PERF_EVENTS
880 case TRACE_REG_PERF_REGISTER:
881 return probe_event_enable(tu, TP_FLAG_PROFILE, uprobe_perf_filter);
882
883 case TRACE_REG_PERF_UNREGISTER:
884 probe_event_disable(tu, TP_FLAG_PROFILE);
885 return 0;
886
887 case TRACE_REG_PERF_OPEN:
888 return uprobe_perf_open(tu, data);
889
890 case TRACE_REG_PERF_CLOSE:
891 return uprobe_perf_close(tu, data);
892
893 #endif
894 default:
895 return 0;
896 }
897 return 0;
898 }
899
900 static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs)
901 {
902 struct trace_uprobe *tu;
903 int ret = 0;
904
905 tu = container_of(con, struct trace_uprobe, consumer);
906 tu->nhit++;
907
908 if (tu->flags & TP_FLAG_TRACE)
909 ret |= uprobe_trace_func(tu, regs);
910
911 #ifdef CONFIG_PERF_EVENTS
912 if (tu->flags & TP_FLAG_PROFILE)
913 ret |= uprobe_perf_func(tu, regs);
914 #endif
915 return ret;
916 }
917
918 static int uretprobe_dispatcher(struct uprobe_consumer *con,
919 unsigned long func, struct pt_regs *regs)
920 {
921 struct trace_uprobe *tu;
922
923 tu = container_of(con, struct trace_uprobe, consumer);
924
925 if (tu->flags & TP_FLAG_TRACE)
926 uretprobe_trace_func(tu, func, regs);
927
928 #ifdef CONFIG_PERF_EVENTS
929 if (tu->flags & TP_FLAG_PROFILE)
930 uretprobe_perf_func(tu, func, regs);
931 #endif
932 return 0;
933 }
934
935 static struct trace_event_functions uprobe_funcs = {
936 .trace = print_uprobe_event
937 };
938
939 static int register_uprobe_event(struct trace_uprobe *tu)
940 {
941 struct ftrace_event_call *call = &tu->call;
942 int ret;
943
944 /* Initialize ftrace_event_call */
945 INIT_LIST_HEAD(&call->class->fields);
946 call->event.funcs = &uprobe_funcs;
947 call->class->define_fields = uprobe_event_define_fields;
948
949 if (set_print_fmt(tu) < 0)
950 return -ENOMEM;
951
952 ret = register_ftrace_event(&call->event);
953 if (!ret) {
954 kfree(call->print_fmt);
955 return -ENODEV;
956 }
957 call->flags = 0;
958 call->class->reg = trace_uprobe_register;
959 call->data = tu;
960 ret = trace_add_event_call(call);
961
962 if (ret) {
963 pr_info("Failed to register uprobe event: %s\n", call->name);
964 kfree(call->print_fmt);
965 unregister_ftrace_event(&call->event);
966 }
967
968 return ret;
969 }
970
971 static void unregister_uprobe_event(struct trace_uprobe *tu)
972 {
973 /* tu->event is unregistered in trace_remove_event_call() */
974 trace_remove_event_call(&tu->call);
975 kfree(tu->call.print_fmt);
976 tu->call.print_fmt = NULL;
977 }
978
979 /* Make a trace interface for controling probe points */
980 static __init int init_uprobe_trace(void)
981 {
982 struct dentry *d_tracer;
983
984 d_tracer = tracing_init_dentry();
985 if (!d_tracer)
986 return 0;
987
988 trace_create_file("uprobe_events", 0644, d_tracer,
989 NULL, &uprobe_events_ops);
990 /* Profile interface */
991 trace_create_file("uprobe_profile", 0444, d_tracer,
992 NULL, &uprobe_profile_ops);
993 return 0;
994 }
995
996 fs_initcall(init_uprobe_trace);
Linus' kernel tree