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