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[deliverable/linux.git] / kernel / trace / trace_uprobe.c
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 trace_uprobe_filter filter;
55 struct uprobe_consumer consumer;
56 struct inode *inode;
57 char *filename;
58 unsigned long offset;
59 unsigned long nhit;
60 struct trace_probe tp;
61 };
62
63 #define SIZEOF_TRACE_UPROBE(n) \
64 (offsetof(struct trace_uprobe, tp.args) + \
65 (sizeof(struct probe_arg) * (n)))
66
67 static int register_uprobe_event(struct trace_uprobe *tu);
68 static int unregister_uprobe_event(struct trace_uprobe *tu);
69
70 static DEFINE_MUTEX(uprobe_lock);
71 static LIST_HEAD(uprobe_list);
72
73 struct uprobe_dispatch_data {
74 struct trace_uprobe *tu;
75 unsigned long bp_addr;
76 };
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 #ifdef CONFIG_STACK_GROWSUP
83 static unsigned long adjust_stack_addr(unsigned long addr, unsigned int n)
84 {
85 return addr - (n * sizeof(long));
86 }
87 #else
88 static unsigned long adjust_stack_addr(unsigned long addr, unsigned int n)
89 {
90 return addr + (n * sizeof(long));
91 }
92 #endif
93
94 static unsigned long get_user_stack_nth(struct pt_regs *regs, unsigned int n)
95 {
96 unsigned long ret;
97 unsigned long addr = user_stack_pointer(regs);
98
99 addr = adjust_stack_addr(addr, n);
100
101 if (copy_from_user(&ret, (void __force __user *) addr, sizeof(ret)))
102 return 0;
103
104 return ret;
105 }
106
107 /*
108 * Uprobes-specific fetch functions
109 */
110 #define DEFINE_FETCH_stack(type) \
111 static void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs, \
112 void *offset, void *dest) \
113 { \
114 *(type *)dest = (type)get_user_stack_nth(regs, \
115 ((unsigned long)offset)); \
116 }
117 DEFINE_BASIC_FETCH_FUNCS(stack)
118 /* No string on the stack entry */
119 #define fetch_stack_string NULL
120 #define fetch_stack_string_size NULL
121
122 #define DEFINE_FETCH_memory(type) \
123 static void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs, \
124 void *addr, void *dest) \
125 { \
126 type retval; \
127 void __user *vaddr = (void __force __user *) addr; \
128 \
129 if (copy_from_user(&retval, vaddr, sizeof(type))) \
130 *(type *)dest = 0; \
131 else \
132 *(type *) dest = retval; \
133 }
134 DEFINE_BASIC_FETCH_FUNCS(memory)
135 /*
136 * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
137 * length and relative data location.
138 */
139 static void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,
140 void *addr, void *dest)
141 {
142 long ret;
143 u32 rloc = *(u32 *)dest;
144 int maxlen = get_rloc_len(rloc);
145 u8 *dst = get_rloc_data(dest);
146 void __user *src = (void __force __user *) addr;
147
148 if (!maxlen)
149 return;
150
151 ret = strncpy_from_user(dst, src, maxlen);
152
153 if (ret < 0) { /* Failed to fetch string */
154 ((u8 *)get_rloc_data(dest))[0] = '\0';
155 *(u32 *)dest = make_data_rloc(0, get_rloc_offs(rloc));
156 } else {
157 *(u32 *)dest = make_data_rloc(ret, get_rloc_offs(rloc));
158 }
159 }
160
161 static void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
162 void *addr, void *dest)
163 {
164 int len;
165 void __user *vaddr = (void __force __user *) addr;
166
167 len = strnlen_user(vaddr, MAX_STRING_SIZE);
168
169 if (len == 0 || len > MAX_STRING_SIZE) /* Failed to check length */
170 *(u32 *)dest = 0;
171 else
172 *(u32 *)dest = len;
173 }
174
175 static unsigned long translate_user_vaddr(void *file_offset)
176 {
177 unsigned long base_addr;
178 struct uprobe_dispatch_data *udd;
179
180 udd = (void *) current->utask->vaddr;
181
182 base_addr = udd->bp_addr - udd->tu->offset;
183 return base_addr + (unsigned long)file_offset;
184 }
185
186 #define DEFINE_FETCH_file_offset(type) \
187 static void FETCH_FUNC_NAME(file_offset, type)(struct pt_regs *regs, \
188 void *offset, void *dest)\
189 { \
190 void *vaddr = (void *)translate_user_vaddr(offset); \
191 \
192 FETCH_FUNC_NAME(memory, type)(regs, vaddr, dest); \
193 }
194 DEFINE_BASIC_FETCH_FUNCS(file_offset)
195 DEFINE_FETCH_file_offset(string)
196 DEFINE_FETCH_file_offset(string_size)
197
198 /* Fetch type information table */
199 const struct fetch_type uprobes_fetch_type_table[] = {
200 /* Special types */
201 [FETCH_TYPE_STRING] = __ASSIGN_FETCH_TYPE("string", string, string,
202 sizeof(u32), 1, "__data_loc char[]"),
203 [FETCH_TYPE_STRSIZE] = __ASSIGN_FETCH_TYPE("string_size", u32,
204 string_size, sizeof(u32), 0, "u32"),
205 /* Basic types */
206 ASSIGN_FETCH_TYPE(u8, u8, 0),
207 ASSIGN_FETCH_TYPE(u16, u16, 0),
208 ASSIGN_FETCH_TYPE(u32, u32, 0),
209 ASSIGN_FETCH_TYPE(u64, u64, 0),
210 ASSIGN_FETCH_TYPE(s8, u8, 1),
211 ASSIGN_FETCH_TYPE(s16, u16, 1),
212 ASSIGN_FETCH_TYPE(s32, u32, 1),
213 ASSIGN_FETCH_TYPE(s64, u64, 1),
214
215 ASSIGN_FETCH_TYPE_END
216 };
217
218 static inline void init_trace_uprobe_filter(struct trace_uprobe_filter *filter)
219 {
220 rwlock_init(&filter->rwlock);
221 filter->nr_systemwide = 0;
222 INIT_LIST_HEAD(&filter->perf_events);
223 }
224
225 static inline bool uprobe_filter_is_empty(struct trace_uprobe_filter *filter)
226 {
227 return !filter->nr_systemwide && list_empty(&filter->perf_events);
228 }
229
230 static inline bool is_ret_probe(struct trace_uprobe *tu)
231 {
232 return tu->consumer.ret_handler != NULL;
233 }
234
235 /*
236 * Allocate new trace_uprobe and initialize it (including uprobes).
237 */
238 static struct trace_uprobe *
239 alloc_trace_uprobe(const char *group, const char *event, int nargs, bool is_ret)
240 {
241 struct trace_uprobe *tu;
242
243 if (!event || !is_good_name(event))
244 return ERR_PTR(-EINVAL);
245
246 if (!group || !is_good_name(group))
247 return ERR_PTR(-EINVAL);
248
249 tu = kzalloc(SIZEOF_TRACE_UPROBE(nargs), GFP_KERNEL);
250 if (!tu)
251 return ERR_PTR(-ENOMEM);
252
253 tu->tp.call.class = &tu->tp.class;
254 tu->tp.call.name = kstrdup(event, GFP_KERNEL);
255 if (!tu->tp.call.name)
256 goto error;
257
258 tu->tp.class.system = kstrdup(group, GFP_KERNEL);
259 if (!tu->tp.class.system)
260 goto error;
261
262 INIT_LIST_HEAD(&tu->list);
263 INIT_LIST_HEAD(&tu->tp.files);
264 tu->consumer.handler = uprobe_dispatcher;
265 if (is_ret)
266 tu->consumer.ret_handler = uretprobe_dispatcher;
267 init_trace_uprobe_filter(&tu->filter);
268 return tu;
269
270 error:
271 kfree(tu->tp.call.name);
272 kfree(tu);
273
274 return ERR_PTR(-ENOMEM);
275 }
276
277 static void free_trace_uprobe(struct trace_uprobe *tu)
278 {
279 int i;
280
281 for (i = 0; i < tu->tp.nr_args; i++)
282 traceprobe_free_probe_arg(&tu->tp.args[i]);
283
284 iput(tu->inode);
285 kfree(tu->tp.call.class->system);
286 kfree(tu->tp.call.name);
287 kfree(tu->filename);
288 kfree(tu);
289 }
290
291 static struct trace_uprobe *find_probe_event(const char *event, const char *group)
292 {
293 struct trace_uprobe *tu;
294
295 list_for_each_entry(tu, &uprobe_list, list)
296 if (strcmp(ftrace_event_name(&tu->tp.call), event) == 0 &&
297 strcmp(tu->tp.call.class->system, group) == 0)
298 return tu;
299
300 return NULL;
301 }
302
303 /* Unregister a trace_uprobe and probe_event: call with locking uprobe_lock */
304 static int unregister_trace_uprobe(struct trace_uprobe *tu)
305 {
306 int ret;
307
308 ret = unregister_uprobe_event(tu);
309 if (ret)
310 return ret;
311
312 list_del(&tu->list);
313 free_trace_uprobe(tu);
314 return 0;
315 }
316
317 /* Register a trace_uprobe and probe_event */
318 static int register_trace_uprobe(struct trace_uprobe *tu)
319 {
320 struct trace_uprobe *old_tu;
321 int ret;
322
323 mutex_lock(&uprobe_lock);
324
325 /* register as an event */
326 old_tu = find_probe_event(ftrace_event_name(&tu->tp.call),
327 tu->tp.call.class->system);
328 if (old_tu) {
329 /* delete old event */
330 ret = unregister_trace_uprobe(old_tu);
331 if (ret)
332 goto end;
333 }
334
335 ret = register_uprobe_event(tu);
336 if (ret) {
337 pr_warning("Failed to register probe event(%d)\n", ret);
338 goto end;
339 }
340
341 list_add_tail(&tu->list, &uprobe_list);
342
343 end:
344 mutex_unlock(&uprobe_lock);
345
346 return ret;
347 }
348
349 /*
350 * Argument syntax:
351 * - Add uprobe: p|r[:[GRP/]EVENT] PATH:OFFSET [FETCHARGS]
352 *
353 * - Remove uprobe: -:[GRP/]EVENT
354 */
355 static int create_trace_uprobe(int argc, char **argv)
356 {
357 struct trace_uprobe *tu;
358 struct inode *inode;
359 char *arg, *event, *group, *filename;
360 char buf[MAX_EVENT_NAME_LEN];
361 struct path path;
362 unsigned long offset;
363 bool is_delete, is_return;
364 int i, ret;
365
366 inode = NULL;
367 ret = 0;
368 is_delete = false;
369 is_return = false;
370 event = NULL;
371 group = NULL;
372
373 /* argc must be >= 1 */
374 if (argv[0][0] == '-')
375 is_delete = true;
376 else if (argv[0][0] == 'r')
377 is_return = true;
378 else if (argv[0][0] != 'p') {
379 pr_info("Probe definition must be started with 'p', 'r' or '-'.\n");
380 return -EINVAL;
381 }
382
383 if (argv[0][1] == ':') {
384 event = &argv[0][2];
385 arg = strchr(event, '/');
386
387 if (arg) {
388 group = event;
389 event = arg + 1;
390 event[-1] = '\0';
391
392 if (strlen(group) == 0) {
393 pr_info("Group name is not specified\n");
394 return -EINVAL;
395 }
396 }
397 if (strlen(event) == 0) {
398 pr_info("Event name is not specified\n");
399 return -EINVAL;
400 }
401 }
402 if (!group)
403 group = UPROBE_EVENT_SYSTEM;
404
405 if (is_delete) {
406 int ret;
407
408 if (!event) {
409 pr_info("Delete command needs an event name.\n");
410 return -EINVAL;
411 }
412 mutex_lock(&uprobe_lock);
413 tu = find_probe_event(event, group);
414
415 if (!tu) {
416 mutex_unlock(&uprobe_lock);
417 pr_info("Event %s/%s doesn't exist.\n", group, event);
418 return -ENOENT;
419 }
420 /* delete an event */
421 ret = unregister_trace_uprobe(tu);
422 mutex_unlock(&uprobe_lock);
423 return ret;
424 }
425
426 if (argc < 2) {
427 pr_info("Probe point is not specified.\n");
428 return -EINVAL;
429 }
430 if (isdigit(argv[1][0])) {
431 pr_info("probe point must be have a filename.\n");
432 return -EINVAL;
433 }
434 arg = strchr(argv[1], ':');
435 if (!arg) {
436 ret = -EINVAL;
437 goto fail_address_parse;
438 }
439
440 *arg++ = '\0';
441 filename = argv[1];
442 ret = kern_path(filename, LOOKUP_FOLLOW, &path);
443 if (ret)
444 goto fail_address_parse;
445
446 inode = igrab(path.dentry->d_inode);
447 path_put(&path);
448
449 if (!inode || !S_ISREG(inode->i_mode)) {
450 ret = -EINVAL;
451 goto fail_address_parse;
452 }
453
454 ret = kstrtoul(arg, 0, &offset);
455 if (ret)
456 goto fail_address_parse;
457
458 argc -= 2;
459 argv += 2;
460
461 /* setup a probe */
462 if (!event) {
463 char *tail;
464 char *ptr;
465
466 tail = kstrdup(kbasename(filename), GFP_KERNEL);
467 if (!tail) {
468 ret = -ENOMEM;
469 goto fail_address_parse;
470 }
471
472 ptr = strpbrk(tail, ".-_");
473 if (ptr)
474 *ptr = '\0';
475
476 snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_0x%lx", 'p', tail, offset);
477 event = buf;
478 kfree(tail);
479 }
480
481 tu = alloc_trace_uprobe(group, event, argc, is_return);
482 if (IS_ERR(tu)) {
483 pr_info("Failed to allocate trace_uprobe.(%d)\n", (int)PTR_ERR(tu));
484 ret = PTR_ERR(tu);
485 goto fail_address_parse;
486 }
487 tu->offset = offset;
488 tu->inode = inode;
489 tu->filename = kstrdup(filename, GFP_KERNEL);
490
491 if (!tu->filename) {
492 pr_info("Failed to allocate filename.\n");
493 ret = -ENOMEM;
494 goto error;
495 }
496
497 /* parse arguments */
498 ret = 0;
499 for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
500 struct probe_arg *parg = &tu->tp.args[i];
501
502 /* Increment count for freeing args in error case */
503 tu->tp.nr_args++;
504
505 /* Parse argument name */
506 arg = strchr(argv[i], '=');
507 if (arg) {
508 *arg++ = '\0';
509 parg->name = kstrdup(argv[i], GFP_KERNEL);
510 } else {
511 arg = argv[i];
512 /* If argument name is omitted, set "argN" */
513 snprintf(buf, MAX_EVENT_NAME_LEN, "arg%d", i + 1);
514 parg->name = kstrdup(buf, GFP_KERNEL);
515 }
516
517 if (!parg->name) {
518 pr_info("Failed to allocate argument[%d] name.\n", i);
519 ret = -ENOMEM;
520 goto error;
521 }
522
523 if (!is_good_name(parg->name)) {
524 pr_info("Invalid argument[%d] name: %s\n", i, parg->name);
525 ret = -EINVAL;
526 goto error;
527 }
528
529 if (traceprobe_conflict_field_name(parg->name, tu->tp.args, i)) {
530 pr_info("Argument[%d] name '%s' conflicts with "
531 "another field.\n", i, argv[i]);
532 ret = -EINVAL;
533 goto error;
534 }
535
536 /* Parse fetch argument */
537 ret = traceprobe_parse_probe_arg(arg, &tu->tp.size, parg,
538 is_return, false);
539 if (ret) {
540 pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
541 goto error;
542 }
543 }
544
545 ret = register_trace_uprobe(tu);
546 if (ret)
547 goto error;
548 return 0;
549
550 error:
551 free_trace_uprobe(tu);
552 return ret;
553
554 fail_address_parse:
555 iput(inode);
556
557 pr_info("Failed to parse address or file.\n");
558
559 return ret;
560 }
561
562 static int cleanup_all_probes(void)
563 {
564 struct trace_uprobe *tu;
565 int ret = 0;
566
567 mutex_lock(&uprobe_lock);
568 while (!list_empty(&uprobe_list)) {
569 tu = list_entry(uprobe_list.next, struct trace_uprobe, list);
570 ret = unregister_trace_uprobe(tu);
571 if (ret)
572 break;
573 }
574 mutex_unlock(&uprobe_lock);
575 return ret;
576 }
577
578 /* Probes listing interfaces */
579 static void *probes_seq_start(struct seq_file *m, loff_t *pos)
580 {
581 mutex_lock(&uprobe_lock);
582 return seq_list_start(&uprobe_list, *pos);
583 }
584
585 static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
586 {
587 return seq_list_next(v, &uprobe_list, pos);
588 }
589
590 static void probes_seq_stop(struct seq_file *m, void *v)
591 {
592 mutex_unlock(&uprobe_lock);
593 }
594
595 static int probes_seq_show(struct seq_file *m, void *v)
596 {
597 struct trace_uprobe *tu = v;
598 char c = is_ret_probe(tu) ? 'r' : 'p';
599 int i;
600
601 seq_printf(m, "%c:%s/%s", c, tu->tp.call.class->system,
602 ftrace_event_name(&tu->tp.call));
603 seq_printf(m, " %s:0x%p", tu->filename, (void *)tu->offset);
604
605 for (i = 0; i < tu->tp.nr_args; i++)
606 seq_printf(m, " %s=%s", tu->tp.args[i].name, tu->tp.args[i].comm);
607
608 seq_putc(m, '\n');
609 return 0;
610 }
611
612 static const struct seq_operations probes_seq_op = {
613 .start = probes_seq_start,
614 .next = probes_seq_next,
615 .stop = probes_seq_stop,
616 .show = probes_seq_show
617 };
618
619 static int probes_open(struct inode *inode, struct file *file)
620 {
621 int ret;
622
623 if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
624 ret = cleanup_all_probes();
625 if (ret)
626 return ret;
627 }
628
629 return seq_open(file, &probes_seq_op);
630 }
631
632 static ssize_t probes_write(struct file *file, const char __user *buffer,
633 size_t count, loff_t *ppos)
634 {
635 return traceprobe_probes_write(file, buffer, count, ppos, create_trace_uprobe);
636 }
637
638 static const struct file_operations uprobe_events_ops = {
639 .owner = THIS_MODULE,
640 .open = probes_open,
641 .read = seq_read,
642 .llseek = seq_lseek,
643 .release = seq_release,
644 .write = probes_write,
645 };
646
647 /* Probes profiling interfaces */
648 static int probes_profile_seq_show(struct seq_file *m, void *v)
649 {
650 struct trace_uprobe *tu = v;
651
652 seq_printf(m, " %s %-44s %15lu\n", tu->filename,
653 ftrace_event_name(&tu->tp.call), tu->nhit);
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 uprobe_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 struct uprobe_cpu_buffer {
678 struct mutex mutex;
679 void *buf;
680 };
681 static struct uprobe_cpu_buffer __percpu *uprobe_cpu_buffer;
682 static int uprobe_buffer_refcnt;
683
684 static int uprobe_buffer_init(void)
685 {
686 int cpu, err_cpu;
687
688 uprobe_cpu_buffer = alloc_percpu(struct uprobe_cpu_buffer);
689 if (uprobe_cpu_buffer == NULL)
690 return -ENOMEM;
691
692 for_each_possible_cpu(cpu) {
693 struct page *p = alloc_pages_node(cpu_to_node(cpu),
694 GFP_KERNEL, 0);
695 if (p == NULL) {
696 err_cpu = cpu;
697 goto err;
698 }
699 per_cpu_ptr(uprobe_cpu_buffer, cpu)->buf = page_address(p);
700 mutex_init(&per_cpu_ptr(uprobe_cpu_buffer, cpu)->mutex);
701 }
702
703 return 0;
704
705 err:
706 for_each_possible_cpu(cpu) {
707 if (cpu == err_cpu)
708 break;
709 free_page((unsigned long)per_cpu_ptr(uprobe_cpu_buffer, cpu)->buf);
710 }
711
712 free_percpu(uprobe_cpu_buffer);
713 return -ENOMEM;
714 }
715
716 static int uprobe_buffer_enable(void)
717 {
718 int ret = 0;
719
720 BUG_ON(!mutex_is_locked(&event_mutex));
721
722 if (uprobe_buffer_refcnt++ == 0) {
723 ret = uprobe_buffer_init();
724 if (ret < 0)
725 uprobe_buffer_refcnt--;
726 }
727
728 return ret;
729 }
730
731 static void uprobe_buffer_disable(void)
732 {
733 int cpu;
734
735 BUG_ON(!mutex_is_locked(&event_mutex));
736
737 if (--uprobe_buffer_refcnt == 0) {
738 for_each_possible_cpu(cpu)
739 free_page((unsigned long)per_cpu_ptr(uprobe_cpu_buffer,
740 cpu)->buf);
741
742 free_percpu(uprobe_cpu_buffer);
743 uprobe_cpu_buffer = NULL;
744 }
745 }
746
747 static struct uprobe_cpu_buffer *uprobe_buffer_get(void)
748 {
749 struct uprobe_cpu_buffer *ucb;
750 int cpu;
751
752 cpu = raw_smp_processor_id();
753 ucb = per_cpu_ptr(uprobe_cpu_buffer, cpu);
754
755 /*
756 * Use per-cpu buffers for fastest access, but we might migrate
757 * so the mutex makes sure we have sole access to it.
758 */
759 mutex_lock(&ucb->mutex);
760
761 return ucb;
762 }
763
764 static void uprobe_buffer_put(struct uprobe_cpu_buffer *ucb)
765 {
766 mutex_unlock(&ucb->mutex);
767 }
768
769 static void __uprobe_trace_func(struct trace_uprobe *tu,
770 unsigned long func, struct pt_regs *regs,
771 struct uprobe_cpu_buffer *ucb, int dsize,
772 struct ftrace_event_file *ftrace_file)
773 {
774 struct uprobe_trace_entry_head *entry;
775 struct ring_buffer_event *event;
776 struct ring_buffer *buffer;
777 void *data;
778 int size, esize;
779 struct ftrace_event_call *call = &tu->tp.call;
780
781 WARN_ON(call != ftrace_file->event_call);
782
783 if (WARN_ON_ONCE(tu->tp.size + dsize > PAGE_SIZE))
784 return;
785
786 if (ftrace_trigger_soft_disabled(ftrace_file))
787 return;
788
789 esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
790 size = esize + tu->tp.size + dsize;
791 event = trace_event_buffer_lock_reserve(&buffer, ftrace_file,
792 call->event.type, size, 0, 0);
793 if (!event)
794 return;
795
796 entry = ring_buffer_event_data(event);
797 if (is_ret_probe(tu)) {
798 entry->vaddr[0] = func;
799 entry->vaddr[1] = instruction_pointer(regs);
800 data = DATAOF_TRACE_ENTRY(entry, true);
801 } else {
802 entry->vaddr[0] = instruction_pointer(regs);
803 data = DATAOF_TRACE_ENTRY(entry, false);
804 }
805
806 memcpy(data, ucb->buf, tu->tp.size + dsize);
807
808 event_trigger_unlock_commit(ftrace_file, buffer, event, entry, 0, 0);
809 }
810
811 /* uprobe handler */
812 static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs,
813 struct uprobe_cpu_buffer *ucb, int dsize)
814 {
815 struct event_file_link *link;
816
817 if (is_ret_probe(tu))
818 return 0;
819
820 rcu_read_lock();
821 list_for_each_entry_rcu(link, &tu->tp.files, list)
822 __uprobe_trace_func(tu, 0, regs, ucb, dsize, link->file);
823 rcu_read_unlock();
824
825 return 0;
826 }
827
828 static void uretprobe_trace_func(struct trace_uprobe *tu, unsigned long func,
829 struct pt_regs *regs,
830 struct uprobe_cpu_buffer *ucb, int dsize)
831 {
832 struct event_file_link *link;
833
834 rcu_read_lock();
835 list_for_each_entry_rcu(link, &tu->tp.files, list)
836 __uprobe_trace_func(tu, func, regs, ucb, dsize, link->file);
837 rcu_read_unlock();
838 }
839
840 /* Event entry printers */
841 static enum print_line_t
842 print_uprobe_event(struct trace_iterator *iter, int flags, struct trace_event *event)
843 {
844 struct uprobe_trace_entry_head *entry;
845 struct trace_seq *s = &iter->seq;
846 struct trace_uprobe *tu;
847 u8 *data;
848 int i;
849
850 entry = (struct uprobe_trace_entry_head *)iter->ent;
851 tu = container_of(event, struct trace_uprobe, tp.call.event);
852
853 if (is_ret_probe(tu)) {
854 trace_seq_printf(s, "%s: (0x%lx <- 0x%lx)",
855 ftrace_event_name(&tu->tp.call),
856 entry->vaddr[1], entry->vaddr[0]);
857 data = DATAOF_TRACE_ENTRY(entry, true);
858 } else {
859 trace_seq_printf(s, "%s: (0x%lx)",
860 ftrace_event_name(&tu->tp.call),
861 entry->vaddr[0]);
862 data = DATAOF_TRACE_ENTRY(entry, false);
863 }
864
865 for (i = 0; i < tu->tp.nr_args; i++) {
866 struct probe_arg *parg = &tu->tp.args[i];
867
868 if (!parg->type->print(s, parg->name, data + parg->offset, entry))
869 goto out;
870 }
871
872 trace_seq_putc(s, '\n');
873
874 out:
875 return trace_handle_return(s);
876 }
877
878 typedef bool (*filter_func_t)(struct uprobe_consumer *self,
879 enum uprobe_filter_ctx ctx,
880 struct mm_struct *mm);
881
882 static int
883 probe_event_enable(struct trace_uprobe *tu, struct ftrace_event_file *file,
884 filter_func_t filter)
885 {
886 bool enabled = trace_probe_is_enabled(&tu->tp);
887 struct event_file_link *link = NULL;
888 int ret;
889
890 if (file) {
891 if (tu->tp.flags & TP_FLAG_PROFILE)
892 return -EINTR;
893
894 link = kmalloc(sizeof(*link), GFP_KERNEL);
895 if (!link)
896 return -ENOMEM;
897
898 link->file = file;
899 list_add_tail_rcu(&link->list, &tu->tp.files);
900
901 tu->tp.flags |= TP_FLAG_TRACE;
902 } else {
903 if (tu->tp.flags & TP_FLAG_TRACE)
904 return -EINTR;
905
906 tu->tp.flags |= TP_FLAG_PROFILE;
907 }
908
909 WARN_ON(!uprobe_filter_is_empty(&tu->filter));
910
911 if (enabled)
912 return 0;
913
914 ret = uprobe_buffer_enable();
915 if (ret)
916 goto err_flags;
917
918 tu->consumer.filter = filter;
919 ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
920 if (ret)
921 goto err_buffer;
922
923 return 0;
924
925 err_buffer:
926 uprobe_buffer_disable();
927
928 err_flags:
929 if (file) {
930 list_del(&link->list);
931 kfree(link);
932 tu->tp.flags &= ~TP_FLAG_TRACE;
933 } else {
934 tu->tp.flags &= ~TP_FLAG_PROFILE;
935 }
936 return ret;
937 }
938
939 static void
940 probe_event_disable(struct trace_uprobe *tu, struct ftrace_event_file *file)
941 {
942 if (!trace_probe_is_enabled(&tu->tp))
943 return;
944
945 if (file) {
946 struct event_file_link *link;
947
948 link = find_event_file_link(&tu->tp, file);
949 if (!link)
950 return;
951
952 list_del_rcu(&link->list);
953 /* synchronize with u{,ret}probe_trace_func */
954 synchronize_sched();
955 kfree(link);
956
957 if (!list_empty(&tu->tp.files))
958 return;
959 }
960
961 WARN_ON(!uprobe_filter_is_empty(&tu->filter));
962
963 uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
964 tu->tp.flags &= file ? ~TP_FLAG_TRACE : ~TP_FLAG_PROFILE;
965
966 uprobe_buffer_disable();
967 }
968
969 static int uprobe_event_define_fields(struct ftrace_event_call *event_call)
970 {
971 int ret, i, size;
972 struct uprobe_trace_entry_head field;
973 struct trace_uprobe *tu = event_call->data;
974
975 if (is_ret_probe(tu)) {
976 DEFINE_FIELD(unsigned long, vaddr[0], FIELD_STRING_FUNC, 0);
977 DEFINE_FIELD(unsigned long, vaddr[1], FIELD_STRING_RETIP, 0);
978 size = SIZEOF_TRACE_ENTRY(true);
979 } else {
980 DEFINE_FIELD(unsigned long, vaddr[0], FIELD_STRING_IP, 0);
981 size = SIZEOF_TRACE_ENTRY(false);
982 }
983 /* Set argument names as fields */
984 for (i = 0; i < tu->tp.nr_args; i++) {
985 struct probe_arg *parg = &tu->tp.args[i];
986
987 ret = trace_define_field(event_call, parg->type->fmttype,
988 parg->name, size + parg->offset,
989 parg->type->size, parg->type->is_signed,
990 FILTER_OTHER);
991
992 if (ret)
993 return ret;
994 }
995 return 0;
996 }
997
998 #ifdef CONFIG_PERF_EVENTS
999 static bool
1000 __uprobe_perf_filter(struct trace_uprobe_filter *filter, struct mm_struct *mm)
1001 {
1002 struct perf_event *event;
1003
1004 if (filter->nr_systemwide)
1005 return true;
1006
1007 list_for_each_entry(event, &filter->perf_events, hw.tp_list) {
1008 if (event->hw.tp_target->mm == mm)
1009 return true;
1010 }
1011
1012 return false;
1013 }
1014
1015 static inline bool
1016 uprobe_filter_event(struct trace_uprobe *tu, struct perf_event *event)
1017 {
1018 return __uprobe_perf_filter(&tu->filter, event->hw.tp_target->mm);
1019 }
1020
1021 static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event)
1022 {
1023 bool done;
1024
1025 write_lock(&tu->filter.rwlock);
1026 if (event->hw.tp_target) {
1027 list_del(&event->hw.tp_list);
1028 done = tu->filter.nr_systemwide ||
1029 (event->hw.tp_target->flags & PF_EXITING) ||
1030 uprobe_filter_event(tu, event);
1031 } else {
1032 tu->filter.nr_systemwide--;
1033 done = tu->filter.nr_systemwide;
1034 }
1035 write_unlock(&tu->filter.rwlock);
1036
1037 if (!done)
1038 return uprobe_apply(tu->inode, tu->offset, &tu->consumer, false);
1039
1040 return 0;
1041 }
1042
1043 static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event)
1044 {
1045 bool done;
1046 int err;
1047
1048 write_lock(&tu->filter.rwlock);
1049 if (event->hw.tp_target) {
1050 /*
1051 * event->parent != NULL means copy_process(), we can avoid
1052 * uprobe_apply(). current->mm must be probed and we can rely
1053 * on dup_mmap() which preserves the already installed bp's.
1054 *
1055 * attr.enable_on_exec means that exec/mmap will install the
1056 * breakpoints we need.
1057 */
1058 done = tu->filter.nr_systemwide ||
1059 event->parent || event->attr.enable_on_exec ||
1060 uprobe_filter_event(tu, event);
1061 list_add(&event->hw.tp_list, &tu->filter.perf_events);
1062 } else {
1063 done = tu->filter.nr_systemwide;
1064 tu->filter.nr_systemwide++;
1065 }
1066 write_unlock(&tu->filter.rwlock);
1067
1068 err = 0;
1069 if (!done) {
1070 err = uprobe_apply(tu->inode, tu->offset, &tu->consumer, true);
1071 if (err)
1072 uprobe_perf_close(tu, event);
1073 }
1074 return err;
1075 }
1076
1077 static bool uprobe_perf_filter(struct uprobe_consumer *uc,
1078 enum uprobe_filter_ctx ctx, struct mm_struct *mm)
1079 {
1080 struct trace_uprobe *tu;
1081 int ret;
1082
1083 tu = container_of(uc, struct trace_uprobe, consumer);
1084 read_lock(&tu->filter.rwlock);
1085 ret = __uprobe_perf_filter(&tu->filter, mm);
1086 read_unlock(&tu->filter.rwlock);
1087
1088 return ret;
1089 }
1090
1091 static void __uprobe_perf_func(struct trace_uprobe *tu,
1092 unsigned long func, struct pt_regs *regs,
1093 struct uprobe_cpu_buffer *ucb, int dsize)
1094 {
1095 struct ftrace_event_call *call = &tu->tp.call;
1096 struct uprobe_trace_entry_head *entry;
1097 struct hlist_head *head;
1098 void *data;
1099 int size, esize;
1100 int rctx;
1101
1102 esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
1103
1104 size = esize + tu->tp.size + dsize;
1105 size = ALIGN(size + sizeof(u32), sizeof(u64)) - sizeof(u32);
1106 if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, "profile buffer not large enough"))
1107 return;
1108
1109 preempt_disable();
1110 head = this_cpu_ptr(call->perf_events);
1111 if (hlist_empty(head))
1112 goto out;
1113
1114 entry = perf_trace_buf_prepare(size, call->event.type, NULL, &rctx);
1115 if (!entry)
1116 goto out;
1117
1118 if (is_ret_probe(tu)) {
1119 entry->vaddr[0] = func;
1120 entry->vaddr[1] = instruction_pointer(regs);
1121 data = DATAOF_TRACE_ENTRY(entry, true);
1122 } else {
1123 entry->vaddr[0] = instruction_pointer(regs);
1124 data = DATAOF_TRACE_ENTRY(entry, false);
1125 }
1126
1127 memcpy(data, ucb->buf, tu->tp.size + dsize);
1128
1129 if (size - esize > tu->tp.size + dsize) {
1130 int len = tu->tp.size + dsize;
1131
1132 memset(data + len, 0, size - esize - len);
1133 }
1134
1135 perf_trace_buf_submit(entry, size, rctx, 0, 1, regs, head, NULL);
1136 out:
1137 preempt_enable();
1138 }
1139
1140 /* uprobe profile handler */
1141 static int uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs,
1142 struct uprobe_cpu_buffer *ucb, int dsize)
1143 {
1144 if (!uprobe_perf_filter(&tu->consumer, 0, current->mm))
1145 return UPROBE_HANDLER_REMOVE;
1146
1147 if (!is_ret_probe(tu))
1148 __uprobe_perf_func(tu, 0, regs, ucb, dsize);
1149 return 0;
1150 }
1151
1152 static void uretprobe_perf_func(struct trace_uprobe *tu, unsigned long func,
1153 struct pt_regs *regs,
1154 struct uprobe_cpu_buffer *ucb, int dsize)
1155 {
1156 __uprobe_perf_func(tu, func, regs, ucb, dsize);
1157 }
1158 #endif /* CONFIG_PERF_EVENTS */
1159
1160 static int
1161 trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg type,
1162 void *data)
1163 {
1164 struct trace_uprobe *tu = event->data;
1165 struct ftrace_event_file *file = data;
1166
1167 switch (type) {
1168 case TRACE_REG_REGISTER:
1169 return probe_event_enable(tu, file, NULL);
1170
1171 case TRACE_REG_UNREGISTER:
1172 probe_event_disable(tu, file);
1173 return 0;
1174
1175 #ifdef CONFIG_PERF_EVENTS
1176 case TRACE_REG_PERF_REGISTER:
1177 return probe_event_enable(tu, NULL, uprobe_perf_filter);
1178
1179 case TRACE_REG_PERF_UNREGISTER:
1180 probe_event_disable(tu, NULL);
1181 return 0;
1182
1183 case TRACE_REG_PERF_OPEN:
1184 return uprobe_perf_open(tu, data);
1185
1186 case TRACE_REG_PERF_CLOSE:
1187 return uprobe_perf_close(tu, data);
1188
1189 #endif
1190 default:
1191 return 0;
1192 }
1193 return 0;
1194 }
1195
1196 static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs)
1197 {
1198 struct trace_uprobe *tu;
1199 struct uprobe_dispatch_data udd;
1200 struct uprobe_cpu_buffer *ucb;
1201 int dsize, esize;
1202 int ret = 0;
1203
1204
1205 tu = container_of(con, struct trace_uprobe, consumer);
1206 tu->nhit++;
1207
1208 udd.tu = tu;
1209 udd.bp_addr = instruction_pointer(regs);
1210
1211 current->utask->vaddr = (unsigned long) &udd;
1212
1213 if (WARN_ON_ONCE(!uprobe_cpu_buffer))
1214 return 0;
1215
1216 dsize = __get_data_size(&tu->tp, regs);
1217 esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
1218
1219 ucb = uprobe_buffer_get();
1220 store_trace_args(esize, &tu->tp, regs, ucb->buf, dsize);
1221
1222 if (tu->tp.flags & TP_FLAG_TRACE)
1223 ret |= uprobe_trace_func(tu, regs, ucb, dsize);
1224
1225 #ifdef CONFIG_PERF_EVENTS
1226 if (tu->tp.flags & TP_FLAG_PROFILE)
1227 ret |= uprobe_perf_func(tu, regs, ucb, dsize);
1228 #endif
1229 uprobe_buffer_put(ucb);
1230 return ret;
1231 }
1232
1233 static int uretprobe_dispatcher(struct uprobe_consumer *con,
1234 unsigned long func, struct pt_regs *regs)
1235 {
1236 struct trace_uprobe *tu;
1237 struct uprobe_dispatch_data udd;
1238 struct uprobe_cpu_buffer *ucb;
1239 int dsize, esize;
1240
1241 tu = container_of(con, struct trace_uprobe, consumer);
1242
1243 udd.tu = tu;
1244 udd.bp_addr = func;
1245
1246 current->utask->vaddr = (unsigned long) &udd;
1247
1248 if (WARN_ON_ONCE(!uprobe_cpu_buffer))
1249 return 0;
1250
1251 dsize = __get_data_size(&tu->tp, regs);
1252 esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
1253
1254 ucb = uprobe_buffer_get();
1255 store_trace_args(esize, &tu->tp, regs, ucb->buf, dsize);
1256
1257 if (tu->tp.flags & TP_FLAG_TRACE)
1258 uretprobe_trace_func(tu, func, regs, ucb, dsize);
1259
1260 #ifdef CONFIG_PERF_EVENTS
1261 if (tu->tp.flags & TP_FLAG_PROFILE)
1262 uretprobe_perf_func(tu, func, regs, ucb, dsize);
1263 #endif
1264 uprobe_buffer_put(ucb);
1265 return 0;
1266 }
1267
1268 static struct trace_event_functions uprobe_funcs = {
1269 .trace = print_uprobe_event
1270 };
1271
1272 static int register_uprobe_event(struct trace_uprobe *tu)
1273 {
1274 struct ftrace_event_call *call = &tu->tp.call;
1275 int ret;
1276
1277 /* Initialize ftrace_event_call */
1278 INIT_LIST_HEAD(&call->class->fields);
1279 call->event.funcs = &uprobe_funcs;
1280 call->class->define_fields = uprobe_event_define_fields;
1281
1282 if (set_print_fmt(&tu->tp, is_ret_probe(tu)) < 0)
1283 return -ENOMEM;
1284
1285 ret = register_ftrace_event(&call->event);
1286 if (!ret) {
1287 kfree(call->print_fmt);
1288 return -ENODEV;
1289 }
1290
1291 call->class->reg = trace_uprobe_register;
1292 call->data = tu;
1293 ret = trace_add_event_call(call);
1294
1295 if (ret) {
1296 pr_info("Failed to register uprobe event: %s\n",
1297 ftrace_event_name(call));
1298 kfree(call->print_fmt);
1299 unregister_ftrace_event(&call->event);
1300 }
1301
1302 return ret;
1303 }
1304
1305 static int unregister_uprobe_event(struct trace_uprobe *tu)
1306 {
1307 int ret;
1308
1309 /* tu->event is unregistered in trace_remove_event_call() */
1310 ret = trace_remove_event_call(&tu->tp.call);
1311 if (ret)
1312 return ret;
1313 kfree(tu->tp.call.print_fmt);
1314 tu->tp.call.print_fmt = NULL;
1315 return 0;
1316 }
1317
1318 /* Make a trace interface for controling probe points */
1319 static __init int init_uprobe_trace(void)
1320 {
1321 struct dentry *d_tracer;
1322
1323 d_tracer = tracing_init_dentry();
1324 if (IS_ERR(d_tracer))
1325 return 0;
1326
1327 trace_create_file("uprobe_events", 0644, d_tracer,
1328 NULL, &uprobe_events_ops);
1329 /* Profile interface */
1330 trace_create_file("uprobe_profile", 0444, d_tracer,
1331 NULL, &uprobe_profile_ops);
1332 return 0;
1333 }
1334
1335 fs_initcall(init_uprobe_trace);
Linux kernel - Deliverables
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