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Merge git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-3.0-fixes
[deliverable/linux.git] / kernel / trace / trace_kprobe.c
1 /*
2 * Kprobes-based tracing events
3 *
4 * Created by Masami Hiramatsu <mhiramat@redhat.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 */
19
20 #include <linux/module.h>
21 #include <linux/uaccess.h>
22
23 #include "trace_probe.h"
24
25 #define KPROBE_EVENT_SYSTEM "kprobes"
26
27 /**
28 * Kprobe event core functions
29 */
30 struct trace_probe {
31 struct list_head list;
32 struct kretprobe rp; /* Use rp.kp for kprobe use */
33 unsigned long nhit;
34 unsigned int flags; /* For TP_FLAG_* */
35 const char *symbol; /* symbol name */
36 struct ftrace_event_class class;
37 struct ftrace_event_call call;
38 struct list_head files;
39 ssize_t size; /* trace entry size */
40 unsigned int nr_args;
41 struct probe_arg args[];
42 };
43
44 struct event_file_link {
45 struct ftrace_event_file *file;
46 struct list_head list;
47 };
48
49 #define SIZEOF_TRACE_PROBE(n) \
50 (offsetof(struct trace_probe, args) + \
51 (sizeof(struct probe_arg) * (n)))
52
53
54 static __kprobes bool trace_probe_is_return(struct trace_probe *tp)
55 {
56 return tp->rp.handler != NULL;
57 }
58
59 static __kprobes const char *trace_probe_symbol(struct trace_probe *tp)
60 {
61 return tp->symbol ? tp->symbol : "unknown";
62 }
63
64 static __kprobes unsigned long trace_probe_offset(struct trace_probe *tp)
65 {
66 return tp->rp.kp.offset;
67 }
68
69 static __kprobes bool trace_probe_is_enabled(struct trace_probe *tp)
70 {
71 return !!(tp->flags & (TP_FLAG_TRACE | TP_FLAG_PROFILE));
72 }
73
74 static __kprobes bool trace_probe_is_registered(struct trace_probe *tp)
75 {
76 return !!(tp->flags & TP_FLAG_REGISTERED);
77 }
78
79 static __kprobes bool trace_probe_has_gone(struct trace_probe *tp)
80 {
81 return !!(kprobe_gone(&tp->rp.kp));
82 }
83
84 static __kprobes bool trace_probe_within_module(struct trace_probe *tp,
85 struct module *mod)
86 {
87 int len = strlen(mod->name);
88 const char *name = trace_probe_symbol(tp);
89 return strncmp(mod->name, name, len) == 0 && name[len] == ':';
90 }
91
92 static __kprobes bool trace_probe_is_on_module(struct trace_probe *tp)
93 {
94 return !!strchr(trace_probe_symbol(tp), ':');
95 }
96
97 static int register_probe_event(struct trace_probe *tp);
98 static int unregister_probe_event(struct trace_probe *tp);
99
100 static DEFINE_MUTEX(probe_lock);
101 static LIST_HEAD(probe_list);
102
103 static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
104 static int kretprobe_dispatcher(struct kretprobe_instance *ri,
105 struct pt_regs *regs);
106
107 /*
108 * Allocate new trace_probe and initialize it (including kprobes).
109 */
110 static struct trace_probe *alloc_trace_probe(const char *group,
111 const char *event,
112 void *addr,
113 const char *symbol,
114 unsigned long offs,
115 int nargs, bool is_return)
116 {
117 struct trace_probe *tp;
118 int ret = -ENOMEM;
119
120 tp = kzalloc(SIZEOF_TRACE_PROBE(nargs), GFP_KERNEL);
121 if (!tp)
122 return ERR_PTR(ret);
123
124 if (symbol) {
125 tp->symbol = kstrdup(symbol, GFP_KERNEL);
126 if (!tp->symbol)
127 goto error;
128 tp->rp.kp.symbol_name = tp->symbol;
129 tp->rp.kp.offset = offs;
130 } else
131 tp->rp.kp.addr = addr;
132
133 if (is_return)
134 tp->rp.handler = kretprobe_dispatcher;
135 else
136 tp->rp.kp.pre_handler = kprobe_dispatcher;
137
138 if (!event || !is_good_name(event)) {
139 ret = -EINVAL;
140 goto error;
141 }
142
143 tp->call.class = &tp->class;
144 tp->call.name = kstrdup(event, GFP_KERNEL);
145 if (!tp->call.name)
146 goto error;
147
148 if (!group || !is_good_name(group)) {
149 ret = -EINVAL;
150 goto error;
151 }
152
153 tp->class.system = kstrdup(group, GFP_KERNEL);
154 if (!tp->class.system)
155 goto error;
156
157 INIT_LIST_HEAD(&tp->list);
158 INIT_LIST_HEAD(&tp->files);
159 return tp;
160 error:
161 kfree(tp->call.name);
162 kfree(tp->symbol);
163 kfree(tp);
164 return ERR_PTR(ret);
165 }
166
167 static void free_trace_probe(struct trace_probe *tp)
168 {
169 int i;
170
171 for (i = 0; i < tp->nr_args; i++)
172 traceprobe_free_probe_arg(&tp->args[i]);
173
174 kfree(tp->call.class->system);
175 kfree(tp->call.name);
176 kfree(tp->symbol);
177 kfree(tp);
178 }
179
180 static struct trace_probe *find_trace_probe(const char *event,
181 const char *group)
182 {
183 struct trace_probe *tp;
184
185 list_for_each_entry(tp, &probe_list, list)
186 if (strcmp(tp->call.name, event) == 0 &&
187 strcmp(tp->call.class->system, group) == 0)
188 return tp;
189 return NULL;
190 }
191
192 /*
193 * Enable trace_probe
194 * if the file is NULL, enable "perf" handler, or enable "trace" handler.
195 */
196 static int
197 enable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
198 {
199 int ret = 0;
200
201 if (file) {
202 struct event_file_link *link;
203
204 link = kmalloc(sizeof(*link), GFP_KERNEL);
205 if (!link) {
206 ret = -ENOMEM;
207 goto out;
208 }
209
210 link->file = file;
211 list_add_tail_rcu(&link->list, &tp->files);
212
213 tp->flags |= TP_FLAG_TRACE;
214 } else
215 tp->flags |= TP_FLAG_PROFILE;
216
217 if (trace_probe_is_registered(tp) && !trace_probe_has_gone(tp)) {
218 if (trace_probe_is_return(tp))
219 ret = enable_kretprobe(&tp->rp);
220 else
221 ret = enable_kprobe(&tp->rp.kp);
222 }
223 out:
224 return ret;
225 }
226
227 static struct event_file_link *
228 find_event_file_link(struct trace_probe *tp, struct ftrace_event_file *file)
229 {
230 struct event_file_link *link;
231
232 list_for_each_entry(link, &tp->files, list)
233 if (link->file == file)
234 return link;
235
236 return NULL;
237 }
238
239 /*
240 * Disable trace_probe
241 * if the file is NULL, disable "perf" handler, or disable "trace" handler.
242 */
243 static int
244 disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
245 {
246 struct event_file_link *link = NULL;
247 int wait = 0;
248 int ret = 0;
249
250 if (file) {
251 link = find_event_file_link(tp, file);
252 if (!link) {
253 ret = -EINVAL;
254 goto out;
255 }
256
257 list_del_rcu(&link->list);
258 wait = 1;
259 if (!list_empty(&tp->files))
260 goto out;
261
262 tp->flags &= ~TP_FLAG_TRACE;
263 } else
264 tp->flags &= ~TP_FLAG_PROFILE;
265
266 if (!trace_probe_is_enabled(tp) && trace_probe_is_registered(tp)) {
267 if (trace_probe_is_return(tp))
268 disable_kretprobe(&tp->rp);
269 else
270 disable_kprobe(&tp->rp.kp);
271 wait = 1;
272 }
273 out:
274 if (wait) {
275 /*
276 * Synchronize with kprobe_trace_func/kretprobe_trace_func
277 * to ensure disabled (all running handlers are finished).
278 * This is not only for kfree(), but also the caller,
279 * trace_remove_event_call() supposes it for releasing
280 * event_call related objects, which will be accessed in
281 * the kprobe_trace_func/kretprobe_trace_func.
282 */
283 synchronize_sched();
284 kfree(link); /* Ignored if link == NULL */
285 }
286
287 return ret;
288 }
289
290 /* Internal register function - just handle k*probes and flags */
291 static int __register_trace_probe(struct trace_probe *tp)
292 {
293 int i, ret;
294
295 if (trace_probe_is_registered(tp))
296 return -EINVAL;
297
298 for (i = 0; i < tp->nr_args; i++)
299 traceprobe_update_arg(&tp->args[i]);
300
301 /* Set/clear disabled flag according to tp->flag */
302 if (trace_probe_is_enabled(tp))
303 tp->rp.kp.flags &= ~KPROBE_FLAG_DISABLED;
304 else
305 tp->rp.kp.flags |= KPROBE_FLAG_DISABLED;
306
307 if (trace_probe_is_return(tp))
308 ret = register_kretprobe(&tp->rp);
309 else
310 ret = register_kprobe(&tp->rp.kp);
311
312 if (ret == 0)
313 tp->flags |= TP_FLAG_REGISTERED;
314 else {
315 pr_warning("Could not insert probe at %s+%lu: %d\n",
316 trace_probe_symbol(tp), trace_probe_offset(tp), ret);
317 if (ret == -ENOENT && trace_probe_is_on_module(tp)) {
318 pr_warning("This probe might be able to register after"
319 "target module is loaded. Continue.\n");
320 ret = 0;
321 } else if (ret == -EILSEQ) {
322 pr_warning("Probing address(0x%p) is not an "
323 "instruction boundary.\n",
324 tp->rp.kp.addr);
325 ret = -EINVAL;
326 }
327 }
328
329 return ret;
330 }
331
332 /* Internal unregister function - just handle k*probes and flags */
333 static void __unregister_trace_probe(struct trace_probe *tp)
334 {
335 if (trace_probe_is_registered(tp)) {
336 if (trace_probe_is_return(tp))
337 unregister_kretprobe(&tp->rp);
338 else
339 unregister_kprobe(&tp->rp.kp);
340 tp->flags &= ~TP_FLAG_REGISTERED;
341 /* Cleanup kprobe for reuse */
342 if (tp->rp.kp.symbol_name)
343 tp->rp.kp.addr = NULL;
344 }
345 }
346
347 /* Unregister a trace_probe and probe_event: call with locking probe_lock */
348 static int unregister_trace_probe(struct trace_probe *tp)
349 {
350 /* Enabled event can not be unregistered */
351 if (trace_probe_is_enabled(tp))
352 return -EBUSY;
353
354 /* Will fail if probe is being used by ftrace or perf */
355 if (unregister_probe_event(tp))
356 return -EBUSY;
357
358 __unregister_trace_probe(tp);
359 list_del(&tp->list);
360
361 return 0;
362 }
363
364 /* Register a trace_probe and probe_event */
365 static int register_trace_probe(struct trace_probe *tp)
366 {
367 struct trace_probe *old_tp;
368 int ret;
369
370 mutex_lock(&probe_lock);
371
372 /* Delete old (same name) event if exist */
373 old_tp = find_trace_probe(tp->call.name, tp->call.class->system);
374 if (old_tp) {
375 ret = unregister_trace_probe(old_tp);
376 if (ret < 0)
377 goto end;
378 free_trace_probe(old_tp);
379 }
380
381 /* Register new event */
382 ret = register_probe_event(tp);
383 if (ret) {
384 pr_warning("Failed to register probe event(%d)\n", ret);
385 goto end;
386 }
387
388 /* Register k*probe */
389 ret = __register_trace_probe(tp);
390 if (ret < 0)
391 unregister_probe_event(tp);
392 else
393 list_add_tail(&tp->list, &probe_list);
394
395 end:
396 mutex_unlock(&probe_lock);
397 return ret;
398 }
399
400 /* Module notifier call back, checking event on the module */
401 static int trace_probe_module_callback(struct notifier_block *nb,
402 unsigned long val, void *data)
403 {
404 struct module *mod = data;
405 struct trace_probe *tp;
406 int ret;
407
408 if (val != MODULE_STATE_COMING)
409 return NOTIFY_DONE;
410
411 /* Update probes on coming module */
412 mutex_lock(&probe_lock);
413 list_for_each_entry(tp, &probe_list, list) {
414 if (trace_probe_within_module(tp, mod)) {
415 /* Don't need to check busy - this should have gone. */
416 __unregister_trace_probe(tp);
417 ret = __register_trace_probe(tp);
418 if (ret)
419 pr_warning("Failed to re-register probe %s on"
420 "%s: %d\n",
421 tp->call.name, mod->name, ret);
422 }
423 }
424 mutex_unlock(&probe_lock);
425
426 return NOTIFY_DONE;
427 }
428
429 static struct notifier_block trace_probe_module_nb = {
430 .notifier_call = trace_probe_module_callback,
431 .priority = 1 /* Invoked after kprobe module callback */
432 };
433
434 static int create_trace_probe(int argc, char **argv)
435 {
436 /*
437 * Argument syntax:
438 * - Add kprobe: p[:[GRP/]EVENT] [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS]
439 * - Add kretprobe: r[:[GRP/]EVENT] [MOD:]KSYM[+0] [FETCHARGS]
440 * Fetch args:
441 * $retval : fetch return value
442 * $stack : fetch stack address
443 * $stackN : fetch Nth of stack (N:0-)
444 * @ADDR : fetch memory at ADDR (ADDR should be in kernel)
445 * @SYM[+|-offs] : fetch memory at SYM +|- offs (SYM is a data symbol)
446 * %REG : fetch register REG
447 * Dereferencing memory fetch:
448 * +|-offs(ARG) : fetch memory at ARG +|- offs address.
449 * Alias name of args:
450 * NAME=FETCHARG : set NAME as alias of FETCHARG.
451 * Type of args:
452 * FETCHARG:TYPE : use TYPE instead of unsigned long.
453 */
454 struct trace_probe *tp;
455 int i, ret = 0;
456 bool is_return = false, is_delete = false;
457 char *symbol = NULL, *event = NULL, *group = NULL;
458 char *arg;
459 unsigned long offset = 0;
460 void *addr = NULL;
461 char buf[MAX_EVENT_NAME_LEN];
462
463 /* argc must be >= 1 */
464 if (argv[0][0] == 'p')
465 is_return = false;
466 else if (argv[0][0] == 'r')
467 is_return = true;
468 else if (argv[0][0] == '-')
469 is_delete = true;
470 else {
471 pr_info("Probe definition must be started with 'p', 'r' or"
472 " '-'.\n");
473 return -EINVAL;
474 }
475
476 if (argv[0][1] == ':') {
477 event = &argv[0][2];
478 if (strchr(event, '/')) {
479 group = event;
480 event = strchr(group, '/') + 1;
481 event[-1] = '\0';
482 if (strlen(group) == 0) {
483 pr_info("Group name is not specified\n");
484 return -EINVAL;
485 }
486 }
487 if (strlen(event) == 0) {
488 pr_info("Event name is not specified\n");
489 return -EINVAL;
490 }
491 }
492 if (!group)
493 group = KPROBE_EVENT_SYSTEM;
494
495 if (is_delete) {
496 if (!event) {
497 pr_info("Delete command needs an event name.\n");
498 return -EINVAL;
499 }
500 mutex_lock(&probe_lock);
501 tp = find_trace_probe(event, group);
502 if (!tp) {
503 mutex_unlock(&probe_lock);
504 pr_info("Event %s/%s doesn't exist.\n", group, event);
505 return -ENOENT;
506 }
507 /* delete an event */
508 ret = unregister_trace_probe(tp);
509 if (ret == 0)
510 free_trace_probe(tp);
511 mutex_unlock(&probe_lock);
512 return ret;
513 }
514
515 if (argc < 2) {
516 pr_info("Probe point is not specified.\n");
517 return -EINVAL;
518 }
519 if (isdigit(argv[1][0])) {
520 if (is_return) {
521 pr_info("Return probe point must be a symbol.\n");
522 return -EINVAL;
523 }
524 /* an address specified */
525 ret = kstrtoul(&argv[1][0], 0, (unsigned long *)&addr);
526 if (ret) {
527 pr_info("Failed to parse address.\n");
528 return ret;
529 }
530 } else {
531 /* a symbol specified */
532 symbol = argv[1];
533 /* TODO: support .init module functions */
534 ret = traceprobe_split_symbol_offset(symbol, &offset);
535 if (ret) {
536 pr_info("Failed to parse symbol.\n");
537 return ret;
538 }
539 if (offset && is_return) {
540 pr_info("Return probe must be used without offset.\n");
541 return -EINVAL;
542 }
543 }
544 argc -= 2; argv += 2;
545
546 /* setup a probe */
547 if (!event) {
548 /* Make a new event name */
549 if (symbol)
550 snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_%ld",
551 is_return ? 'r' : 'p', symbol, offset);
552 else
553 snprintf(buf, MAX_EVENT_NAME_LEN, "%c_0x%p",
554 is_return ? 'r' : 'p', addr);
555 event = buf;
556 }
557 tp = alloc_trace_probe(group, event, addr, symbol, offset, argc,
558 is_return);
559 if (IS_ERR(tp)) {
560 pr_info("Failed to allocate trace_probe.(%d)\n",
561 (int)PTR_ERR(tp));
562 return PTR_ERR(tp);
563 }
564
565 /* parse arguments */
566 ret = 0;
567 for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
568 /* Increment count for freeing args in error case */
569 tp->nr_args++;
570
571 /* Parse argument name */
572 arg = strchr(argv[i], '=');
573 if (arg) {
574 *arg++ = '\0';
575 tp->args[i].name = kstrdup(argv[i], GFP_KERNEL);
576 } else {
577 arg = argv[i];
578 /* If argument name is omitted, set "argN" */
579 snprintf(buf, MAX_EVENT_NAME_LEN, "arg%d", i + 1);
580 tp->args[i].name = kstrdup(buf, GFP_KERNEL);
581 }
582
583 if (!tp->args[i].name) {
584 pr_info("Failed to allocate argument[%d] name.\n", i);
585 ret = -ENOMEM;
586 goto error;
587 }
588
589 if (!is_good_name(tp->args[i].name)) {
590 pr_info("Invalid argument[%d] name: %s\n",
591 i, tp->args[i].name);
592 ret = -EINVAL;
593 goto error;
594 }
595
596 if (traceprobe_conflict_field_name(tp->args[i].name,
597 tp->args, i)) {
598 pr_info("Argument[%d] name '%s' conflicts with "
599 "another field.\n", i, argv[i]);
600 ret = -EINVAL;
601 goto error;
602 }
603
604 /* Parse fetch argument */
605 ret = traceprobe_parse_probe_arg(arg, &tp->size, &tp->args[i],
606 is_return, true);
607 if (ret) {
608 pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
609 goto error;
610 }
611 }
612
613 ret = register_trace_probe(tp);
614 if (ret)
615 goto error;
616 return 0;
617
618 error:
619 free_trace_probe(tp);
620 return ret;
621 }
622
623 static int release_all_trace_probes(void)
624 {
625 struct trace_probe *tp;
626 int ret = 0;
627
628 mutex_lock(&probe_lock);
629 /* Ensure no probe is in use. */
630 list_for_each_entry(tp, &probe_list, list)
631 if (trace_probe_is_enabled(tp)) {
632 ret = -EBUSY;
633 goto end;
634 }
635 /* TODO: Use batch unregistration */
636 while (!list_empty(&probe_list)) {
637 tp = list_entry(probe_list.next, struct trace_probe, list);
638 ret = unregister_trace_probe(tp);
639 if (ret)
640 goto end;
641 free_trace_probe(tp);
642 }
643
644 end:
645 mutex_unlock(&probe_lock);
646
647 return ret;
648 }
649
650 /* Probes listing interfaces */
651 static void *probes_seq_start(struct seq_file *m, loff_t *pos)
652 {
653 mutex_lock(&probe_lock);
654 return seq_list_start(&probe_list, *pos);
655 }
656
657 static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
658 {
659 return seq_list_next(v, &probe_list, pos);
660 }
661
662 static void probes_seq_stop(struct seq_file *m, void *v)
663 {
664 mutex_unlock(&probe_lock);
665 }
666
667 static int probes_seq_show(struct seq_file *m, void *v)
668 {
669 struct trace_probe *tp = v;
670 int i;
671
672 seq_printf(m, "%c", trace_probe_is_return(tp) ? 'r' : 'p');
673 seq_printf(m, ":%s/%s", tp->call.class->system, tp->call.name);
674
675 if (!tp->symbol)
676 seq_printf(m, " 0x%p", tp->rp.kp.addr);
677 else if (tp->rp.kp.offset)
678 seq_printf(m, " %s+%u", trace_probe_symbol(tp),
679 tp->rp.kp.offset);
680 else
681 seq_printf(m, " %s", trace_probe_symbol(tp));
682
683 for (i = 0; i < tp->nr_args; i++)
684 seq_printf(m, " %s=%s", tp->args[i].name, tp->args[i].comm);
685 seq_printf(m, "\n");
686
687 return 0;
688 }
689
690 static const struct seq_operations probes_seq_op = {
691 .start = probes_seq_start,
692 .next = probes_seq_next,
693 .stop = probes_seq_stop,
694 .show = probes_seq_show
695 };
696
697 static int probes_open(struct inode *inode, struct file *file)
698 {
699 int ret;
700
701 if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
702 ret = release_all_trace_probes();
703 if (ret < 0)
704 return ret;
705 }
706
707 return seq_open(file, &probes_seq_op);
708 }
709
710 static ssize_t probes_write(struct file *file, const char __user *buffer,
711 size_t count, loff_t *ppos)
712 {
713 return traceprobe_probes_write(file, buffer, count, ppos,
714 create_trace_probe);
715 }
716
717 static const struct file_operations kprobe_events_ops = {
718 .owner = THIS_MODULE,
719 .open = probes_open,
720 .read = seq_read,
721 .llseek = seq_lseek,
722 .release = seq_release,
723 .write = probes_write,
724 };
725
726 /* Probes profiling interfaces */
727 static int probes_profile_seq_show(struct seq_file *m, void *v)
728 {
729 struct trace_probe *tp = v;
730
731 seq_printf(m, " %-44s %15lu %15lu\n", tp->call.name, tp->nhit,
732 tp->rp.kp.nmissed);
733
734 return 0;
735 }
736
737 static const struct seq_operations profile_seq_op = {
738 .start = probes_seq_start,
739 .next = probes_seq_next,
740 .stop = probes_seq_stop,
741 .show = probes_profile_seq_show
742 };
743
744 static int profile_open(struct inode *inode, struct file *file)
745 {
746 return seq_open(file, &profile_seq_op);
747 }
748
749 static const struct file_operations kprobe_profile_ops = {
750 .owner = THIS_MODULE,
751 .open = profile_open,
752 .read = seq_read,
753 .llseek = seq_lseek,
754 .release = seq_release,
755 };
756
757 /* Sum up total data length for dynamic arraies (strings) */
758 static __kprobes int __get_data_size(struct trace_probe *tp,
759 struct pt_regs *regs)
760 {
761 int i, ret = 0;
762 u32 len;
763
764 for (i = 0; i < tp->nr_args; i++)
765 if (unlikely(tp->args[i].fetch_size.fn)) {
766 call_fetch(&tp->args[i].fetch_size, regs, &len);
767 ret += len;
768 }
769
770 return ret;
771 }
772
773 /* Store the value of each argument */
774 static __kprobes void store_trace_args(int ent_size, struct trace_probe *tp,
775 struct pt_regs *regs,
776 u8 *data, int maxlen)
777 {
778 int i;
779 u32 end = tp->size;
780 u32 *dl; /* Data (relative) location */
781
782 for (i = 0; i < tp->nr_args; i++) {
783 if (unlikely(tp->args[i].fetch_size.fn)) {
784 /*
785 * First, we set the relative location and
786 * maximum data length to *dl
787 */
788 dl = (u32 *)(data + tp->args[i].offset);
789 *dl = make_data_rloc(maxlen, end - tp->args[i].offset);
790 /* Then try to fetch string or dynamic array data */
791 call_fetch(&tp->args[i].fetch, regs, dl);
792 /* Reduce maximum length */
793 end += get_rloc_len(*dl);
794 maxlen -= get_rloc_len(*dl);
795 /* Trick here, convert data_rloc to data_loc */
796 *dl = convert_rloc_to_loc(*dl,
797 ent_size + tp->args[i].offset);
798 } else
799 /* Just fetching data normally */
800 call_fetch(&tp->args[i].fetch, regs,
801 data + tp->args[i].offset);
802 }
803 }
804
805 /* Kprobe handler */
806 static __kprobes void
807 __kprobe_trace_func(struct trace_probe *tp, struct pt_regs *regs,
808 struct ftrace_event_file *ftrace_file)
809 {
810 struct kprobe_trace_entry_head *entry;
811 struct ring_buffer_event *event;
812 struct ring_buffer *buffer;
813 int size, dsize, pc;
814 unsigned long irq_flags;
815 struct ftrace_event_call *call = &tp->call;
816
817 WARN_ON(call != ftrace_file->event_call);
818
819 if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &ftrace_file->flags))
820 return;
821
822 local_save_flags(irq_flags);
823 pc = preempt_count();
824
825 dsize = __get_data_size(tp, regs);
826 size = sizeof(*entry) + tp->size + dsize;
827
828 event = trace_event_buffer_lock_reserve(&buffer, ftrace_file,
829 call->event.type,
830 size, irq_flags, pc);
831 if (!event)
832 return;
833
834 entry = ring_buffer_event_data(event);
835 entry->ip = (unsigned long)tp->rp.kp.addr;
836 store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
837
838 if (!filter_current_check_discard(buffer, call, entry, event))
839 trace_buffer_unlock_commit_regs(buffer, event,
840 irq_flags, pc, regs);
841 }
842
843 static __kprobes void
844 kprobe_trace_func(struct trace_probe *tp, struct pt_regs *regs)
845 {
846 struct event_file_link *link;
847
848 list_for_each_entry_rcu(link, &tp->files, list)
849 __kprobe_trace_func(tp, regs, link->file);
850 }
851
852 /* Kretprobe handler */
853 static __kprobes void
854 __kretprobe_trace_func(struct trace_probe *tp, struct kretprobe_instance *ri,
855 struct pt_regs *regs,
856 struct ftrace_event_file *ftrace_file)
857 {
858 struct kretprobe_trace_entry_head *entry;
859 struct ring_buffer_event *event;
860 struct ring_buffer *buffer;
861 int size, pc, dsize;
862 unsigned long irq_flags;
863 struct ftrace_event_call *call = &tp->call;
864
865 WARN_ON(call != ftrace_file->event_call);
866
867 if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &ftrace_file->flags))
868 return;
869
870 local_save_flags(irq_flags);
871 pc = preempt_count();
872
873 dsize = __get_data_size(tp, regs);
874 size = sizeof(*entry) + tp->size + dsize;
875
876 event = trace_event_buffer_lock_reserve(&buffer, ftrace_file,
877 call->event.type,
878 size, irq_flags, pc);
879 if (!event)
880 return;
881
882 entry = ring_buffer_event_data(event);
883 entry->func = (unsigned long)tp->rp.kp.addr;
884 entry->ret_ip = (unsigned long)ri->ret_addr;
885 store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
886
887 if (!filter_current_check_discard(buffer, call, entry, event))
888 trace_buffer_unlock_commit_regs(buffer, event,
889 irq_flags, pc, regs);
890 }
891
892 static __kprobes void
893 kretprobe_trace_func(struct trace_probe *tp, struct kretprobe_instance *ri,
894 struct pt_regs *regs)
895 {
896 struct event_file_link *link;
897
898 list_for_each_entry_rcu(link, &tp->files, list)
899 __kretprobe_trace_func(tp, ri, regs, link->file);
900 }
901
902 /* Event entry printers */
903 static enum print_line_t
904 print_kprobe_event(struct trace_iterator *iter, int flags,
905 struct trace_event *event)
906 {
907 struct kprobe_trace_entry_head *field;
908 struct trace_seq *s = &iter->seq;
909 struct trace_probe *tp;
910 u8 *data;
911 int i;
912
913 field = (struct kprobe_trace_entry_head *)iter->ent;
914 tp = container_of(event, struct trace_probe, call.event);
915
916 if (!trace_seq_printf(s, "%s: (", tp->call.name))
917 goto partial;
918
919 if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
920 goto partial;
921
922 if (!trace_seq_puts(s, ")"))
923 goto partial;
924
925 data = (u8 *)&field[1];
926 for (i = 0; i < tp->nr_args; i++)
927 if (!tp->args[i].type->print(s, tp->args[i].name,
928 data + tp->args[i].offset, field))
929 goto partial;
930
931 if (!trace_seq_puts(s, "\n"))
932 goto partial;
933
934 return TRACE_TYPE_HANDLED;
935 partial:
936 return TRACE_TYPE_PARTIAL_LINE;
937 }
938
939 static enum print_line_t
940 print_kretprobe_event(struct trace_iterator *iter, int flags,
941 struct trace_event *event)
942 {
943 struct kretprobe_trace_entry_head *field;
944 struct trace_seq *s = &iter->seq;
945 struct trace_probe *tp;
946 u8 *data;
947 int i;
948
949 field = (struct kretprobe_trace_entry_head *)iter->ent;
950 tp = container_of(event, struct trace_probe, call.event);
951
952 if (!trace_seq_printf(s, "%s: (", tp->call.name))
953 goto partial;
954
955 if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
956 goto partial;
957
958 if (!trace_seq_puts(s, " <- "))
959 goto partial;
960
961 if (!seq_print_ip_sym(s, field->func, flags & ~TRACE_ITER_SYM_OFFSET))
962 goto partial;
963
964 if (!trace_seq_puts(s, ")"))
965 goto partial;
966
967 data = (u8 *)&field[1];
968 for (i = 0; i < tp->nr_args; i++)
969 if (!tp->args[i].type->print(s, tp->args[i].name,
970 data + tp->args[i].offset, field))
971 goto partial;
972
973 if (!trace_seq_puts(s, "\n"))
974 goto partial;
975
976 return TRACE_TYPE_HANDLED;
977 partial:
978 return TRACE_TYPE_PARTIAL_LINE;
979 }
980
981
982 static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
983 {
984 int ret, i;
985 struct kprobe_trace_entry_head field;
986 struct trace_probe *tp = (struct trace_probe *)event_call->data;
987
988 DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
989 /* Set argument names as fields */
990 for (i = 0; i < tp->nr_args; i++) {
991 ret = trace_define_field(event_call, tp->args[i].type->fmttype,
992 tp->args[i].name,
993 sizeof(field) + tp->args[i].offset,
994 tp->args[i].type->size,
995 tp->args[i].type->is_signed,
996 FILTER_OTHER);
997 if (ret)
998 return ret;
999 }
1000 return 0;
1001 }
1002
1003 static int kretprobe_event_define_fields(struct ftrace_event_call *event_call)
1004 {
1005 int ret, i;
1006 struct kretprobe_trace_entry_head field;
1007 struct trace_probe *tp = (struct trace_probe *)event_call->data;
1008
1009 DEFINE_FIELD(unsigned long, func, FIELD_STRING_FUNC, 0);
1010 DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);
1011 /* Set argument names as fields */
1012 for (i = 0; i < tp->nr_args; i++) {
1013 ret = trace_define_field(event_call, tp->args[i].type->fmttype,
1014 tp->args[i].name,
1015 sizeof(field) + tp->args[i].offset,
1016 tp->args[i].type->size,
1017 tp->args[i].type->is_signed,
1018 FILTER_OTHER);
1019 if (ret)
1020 return ret;
1021 }
1022 return 0;
1023 }
1024
1025 static int __set_print_fmt(struct trace_probe *tp, char *buf, int len)
1026 {
1027 int i;
1028 int pos = 0;
1029
1030 const char *fmt, *arg;
1031
1032 if (!trace_probe_is_return(tp)) {
1033 fmt = "(%lx)";
1034 arg = "REC->" FIELD_STRING_IP;
1035 } else {
1036 fmt = "(%lx <- %lx)";
1037 arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
1038 }
1039
1040 /* When len=0, we just calculate the needed length */
1041 #define LEN_OR_ZERO (len ? len - pos : 0)
1042
1043 pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
1044
1045 for (i = 0; i < tp->nr_args; i++) {
1046 pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
1047 tp->args[i].name, tp->args[i].type->fmt);
1048 }
1049
1050 pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
1051
1052 for (i = 0; i < tp->nr_args; i++) {
1053 if (strcmp(tp->args[i].type->name, "string") == 0)
1054 pos += snprintf(buf + pos, LEN_OR_ZERO,
1055 ", __get_str(%s)",
1056 tp->args[i].name);
1057 else
1058 pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
1059 tp->args[i].name);
1060 }
1061
1062 #undef LEN_OR_ZERO
1063
1064 /* return the length of print_fmt */
1065 return pos;
1066 }
1067
1068 static int set_print_fmt(struct trace_probe *tp)
1069 {
1070 int len;
1071 char *print_fmt;
1072
1073 /* First: called with 0 length to calculate the needed length */
1074 len = __set_print_fmt(tp, NULL, 0);
1075 print_fmt = kmalloc(len + 1, GFP_KERNEL);
1076 if (!print_fmt)
1077 return -ENOMEM;
1078
1079 /* Second: actually write the @print_fmt */
1080 __set_print_fmt(tp, print_fmt, len + 1);
1081 tp->call.print_fmt = print_fmt;
1082
1083 return 0;
1084 }
1085
1086 #ifdef CONFIG_PERF_EVENTS
1087
1088 /* Kprobe profile handler */
1089 static __kprobes void
1090 kprobe_perf_func(struct trace_probe *tp, struct pt_regs *regs)
1091 {
1092 struct ftrace_event_call *call = &tp->call;
1093 struct kprobe_trace_entry_head *entry;
1094 struct hlist_head *head;
1095 int size, __size, dsize;
1096 int rctx;
1097
1098 head = this_cpu_ptr(call->perf_events);
1099 if (hlist_empty(head))
1100 return;
1101
1102 dsize = __get_data_size(tp, regs);
1103 __size = sizeof(*entry) + tp->size + dsize;
1104 size = ALIGN(__size + sizeof(u32), sizeof(u64));
1105 size -= sizeof(u32);
1106
1107 entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
1108 if (!entry)
1109 return;
1110
1111 entry->ip = (unsigned long)tp->rp.kp.addr;
1112 memset(&entry[1], 0, dsize);
1113 store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
1114 perf_trace_buf_submit(entry, size, rctx, 0, 1, regs, head, NULL);
1115 }
1116
1117 /* Kretprobe profile handler */
1118 static __kprobes void
1119 kretprobe_perf_func(struct trace_probe *tp, struct kretprobe_instance *ri,
1120 struct pt_regs *regs)
1121 {
1122 struct ftrace_event_call *call = &tp->call;
1123 struct kretprobe_trace_entry_head *entry;
1124 struct hlist_head *head;
1125 int size, __size, dsize;
1126 int rctx;
1127
1128 head = this_cpu_ptr(call->perf_events);
1129 if (hlist_empty(head))
1130 return;
1131
1132 dsize = __get_data_size(tp, regs);
1133 __size = sizeof(*entry) + tp->size + dsize;
1134 size = ALIGN(__size + sizeof(u32), sizeof(u64));
1135 size -= sizeof(u32);
1136
1137 entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
1138 if (!entry)
1139 return;
1140
1141 entry->func = (unsigned long)tp->rp.kp.addr;
1142 entry->ret_ip = (unsigned long)ri->ret_addr;
1143 store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
1144 perf_trace_buf_submit(entry, size, rctx, 0, 1, regs, head, NULL);
1145 }
1146 #endif /* CONFIG_PERF_EVENTS */
1147
1148 /*
1149 * called by perf_trace_init() or __ftrace_set_clr_event() under event_mutex.
1150 *
1151 * kprobe_trace_self_tests_init() does enable_trace_probe/disable_trace_probe
1152 * lockless, but we can't race with this __init function.
1153 */
1154 static __kprobes
1155 int kprobe_register(struct ftrace_event_call *event,
1156 enum trace_reg type, void *data)
1157 {
1158 struct trace_probe *tp = (struct trace_probe *)event->data;
1159 struct ftrace_event_file *file = data;
1160
1161 switch (type) {
1162 case TRACE_REG_REGISTER:
1163 return enable_trace_probe(tp, file);
1164 case TRACE_REG_UNREGISTER:
1165 return disable_trace_probe(tp, file);
1166
1167 #ifdef CONFIG_PERF_EVENTS
1168 case TRACE_REG_PERF_REGISTER:
1169 return enable_trace_probe(tp, NULL);
1170 case TRACE_REG_PERF_UNREGISTER:
1171 return disable_trace_probe(tp, NULL);
1172 case TRACE_REG_PERF_OPEN:
1173 case TRACE_REG_PERF_CLOSE:
1174 case TRACE_REG_PERF_ADD:
1175 case TRACE_REG_PERF_DEL:
1176 return 0;
1177 #endif
1178 }
1179 return 0;
1180 }
1181
1182 static __kprobes
1183 int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs)
1184 {
1185 struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);
1186
1187 tp->nhit++;
1188
1189 if (tp->flags & TP_FLAG_TRACE)
1190 kprobe_trace_func(tp, regs);
1191 #ifdef CONFIG_PERF_EVENTS
1192 if (tp->flags & TP_FLAG_PROFILE)
1193 kprobe_perf_func(tp, regs);
1194 #endif
1195 return 0; /* We don't tweek kernel, so just return 0 */
1196 }
1197
1198 static __kprobes
1199 int kretprobe_dispatcher(struct kretprobe_instance *ri, struct pt_regs *regs)
1200 {
1201 struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
1202
1203 tp->nhit++;
1204
1205 if (tp->flags & TP_FLAG_TRACE)
1206 kretprobe_trace_func(tp, ri, regs);
1207 #ifdef CONFIG_PERF_EVENTS
1208 if (tp->flags & TP_FLAG_PROFILE)
1209 kretprobe_perf_func(tp, ri, regs);
1210 #endif
1211 return 0; /* We don't tweek kernel, so just return 0 */
1212 }
1213
1214 static struct trace_event_functions kretprobe_funcs = {
1215 .trace = print_kretprobe_event
1216 };
1217
1218 static struct trace_event_functions kprobe_funcs = {
1219 .trace = print_kprobe_event
1220 };
1221
1222 static int register_probe_event(struct trace_probe *tp)
1223 {
1224 struct ftrace_event_call *call = &tp->call;
1225 int ret;
1226
1227 /* Initialize ftrace_event_call */
1228 INIT_LIST_HEAD(&call->class->fields);
1229 if (trace_probe_is_return(tp)) {
1230 call->event.funcs = &kretprobe_funcs;
1231 call->class->define_fields = kretprobe_event_define_fields;
1232 } else {
1233 call->event.funcs = &kprobe_funcs;
1234 call->class->define_fields = kprobe_event_define_fields;
1235 }
1236 if (set_print_fmt(tp) < 0)
1237 return -ENOMEM;
1238 ret = register_ftrace_event(&call->event);
1239 if (!ret) {
1240 kfree(call->print_fmt);
1241 return -ENODEV;
1242 }
1243 call->flags = 0;
1244 call->class->reg = kprobe_register;
1245 call->data = tp;
1246 ret = trace_add_event_call(call);
1247 if (ret) {
1248 pr_info("Failed to register kprobe event: %s\n", call->name);
1249 kfree(call->print_fmt);
1250 unregister_ftrace_event(&call->event);
1251 }
1252 return ret;
1253 }
1254
1255 static int unregister_probe_event(struct trace_probe *tp)
1256 {
1257 int ret;
1258
1259 /* tp->event is unregistered in trace_remove_event_call() */
1260 ret = trace_remove_event_call(&tp->call);
1261 if (!ret)
1262 kfree(tp->call.print_fmt);
1263 return ret;
1264 }
1265
1266 /* Make a debugfs interface for controlling probe points */
1267 static __init int init_kprobe_trace(void)
1268 {
1269 struct dentry *d_tracer;
1270 struct dentry *entry;
1271
1272 if (register_module_notifier(&trace_probe_module_nb))
1273 return -EINVAL;
1274
1275 d_tracer = tracing_init_dentry();
1276 if (!d_tracer)
1277 return 0;
1278
1279 entry = debugfs_create_file("kprobe_events", 0644, d_tracer,
1280 NULL, &kprobe_events_ops);
1281
1282 /* Event list interface */
1283 if (!entry)
1284 pr_warning("Could not create debugfs "
1285 "'kprobe_events' entry\n");
1286
1287 /* Profile interface */
1288 entry = debugfs_create_file("kprobe_profile", 0444, d_tracer,
1289 NULL, &kprobe_profile_ops);
1290
1291 if (!entry)
1292 pr_warning("Could not create debugfs "
1293 "'kprobe_profile' entry\n");
1294 return 0;
1295 }
1296 fs_initcall(init_kprobe_trace);
1297
1298
1299 #ifdef CONFIG_FTRACE_STARTUP_TEST
1300
1301 /*
1302 * The "__used" keeps gcc from removing the function symbol
1303 * from the kallsyms table.
1304 */
1305 static __used int kprobe_trace_selftest_target(int a1, int a2, int a3,
1306 int a4, int a5, int a6)
1307 {
1308 return a1 + a2 + a3 + a4 + a5 + a6;
1309 }
1310
1311 static struct ftrace_event_file *
1312 find_trace_probe_file(struct trace_probe *tp, struct trace_array *tr)
1313 {
1314 struct ftrace_event_file *file;
1315
1316 list_for_each_entry(file, &tr->events, list)
1317 if (file->event_call == &tp->call)
1318 return file;
1319
1320 return NULL;
1321 }
1322
1323 /*
1324 * Nobody but us can call enable_trace_probe/disable_trace_probe at this
1325 * stage, we can do this lockless.
1326 */
1327 static __init int kprobe_trace_self_tests_init(void)
1328 {
1329 int ret, warn = 0;
1330 int (*target)(int, int, int, int, int, int);
1331 struct trace_probe *tp;
1332 struct ftrace_event_file *file;
1333
1334 target = kprobe_trace_selftest_target;
1335
1336 pr_info("Testing kprobe tracing: ");
1337
1338 ret = traceprobe_command("p:testprobe kprobe_trace_selftest_target "
1339 "$stack $stack0 +0($stack)",
1340 create_trace_probe);
1341 if (WARN_ON_ONCE(ret)) {
1342 pr_warn("error on probing function entry.\n");
1343 warn++;
1344 } else {
1345 /* Enable trace point */
1346 tp = find_trace_probe("testprobe", KPROBE_EVENT_SYSTEM);
1347 if (WARN_ON_ONCE(tp == NULL)) {
1348 pr_warn("error on getting new probe.\n");
1349 warn++;
1350 } else {
1351 file = find_trace_probe_file(tp, top_trace_array());
1352 if (WARN_ON_ONCE(file == NULL)) {
1353 pr_warn("error on getting probe file.\n");
1354 warn++;
1355 } else
1356 enable_trace_probe(tp, file);
1357 }
1358 }
1359
1360 ret = traceprobe_command("r:testprobe2 kprobe_trace_selftest_target "
1361 "$retval", create_trace_probe);
1362 if (WARN_ON_ONCE(ret)) {
1363 pr_warn("error on probing function return.\n");
1364 warn++;
1365 } else {
1366 /* Enable trace point */
1367 tp = find_trace_probe("testprobe2", KPROBE_EVENT_SYSTEM);
1368 if (WARN_ON_ONCE(tp == NULL)) {
1369 pr_warn("error on getting 2nd new probe.\n");
1370 warn++;
1371 } else {
1372 file = find_trace_probe_file(tp, top_trace_array());
1373 if (WARN_ON_ONCE(file == NULL)) {
1374 pr_warn("error on getting probe file.\n");
1375 warn++;
1376 } else
1377 enable_trace_probe(tp, file);
1378 }
1379 }
1380
1381 if (warn)
1382 goto end;
1383
1384 ret = target(1, 2, 3, 4, 5, 6);
1385
1386 /* Disable trace points before removing it */
1387 tp = find_trace_probe("testprobe", KPROBE_EVENT_SYSTEM);
1388 if (WARN_ON_ONCE(tp == NULL)) {
1389 pr_warn("error on getting test probe.\n");
1390 warn++;
1391 } else {
1392 file = find_trace_probe_file(tp, top_trace_array());
1393 if (WARN_ON_ONCE(file == NULL)) {
1394 pr_warn("error on getting probe file.\n");
1395 warn++;
1396 } else
1397 disable_trace_probe(tp, file);
1398 }
1399
1400 tp = find_trace_probe("testprobe2", KPROBE_EVENT_SYSTEM);
1401 if (WARN_ON_ONCE(tp == NULL)) {
1402 pr_warn("error on getting 2nd test probe.\n");
1403 warn++;
1404 } else {
1405 file = find_trace_probe_file(tp, top_trace_array());
1406 if (WARN_ON_ONCE(file == NULL)) {
1407 pr_warn("error on getting probe file.\n");
1408 warn++;
1409 } else
1410 disable_trace_probe(tp, file);
1411 }
1412
1413 ret = traceprobe_command("-:testprobe", create_trace_probe);
1414 if (WARN_ON_ONCE(ret)) {
1415 pr_warn("error on deleting a probe.\n");
1416 warn++;
1417 }
1418
1419 ret = traceprobe_command("-:testprobe2", create_trace_probe);
1420 if (WARN_ON_ONCE(ret)) {
1421 pr_warn("error on deleting a probe.\n");
1422 warn++;
1423 }
1424
1425 end:
1426 release_all_trace_probes();
1427 if (warn)
1428 pr_cont("NG: Some tests are failed. Please check them.\n");
1429 else
1430 pr_cont("OK\n");
1431 return 0;
1432 }
1433
1434 late_initcall(kprobe_trace_self_tests_init);
1435
1436 #endif
Linux kernel - Deliverables
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