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Merge remote-tracking branch 'ftrace/for-next'
[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 static 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 ASSIGN_FETCH_TYPE_ALIAS(x8, u8, u8, 0),
215 ASSIGN_FETCH_TYPE_ALIAS(x16, u16, u16, 0),
216 ASSIGN_FETCH_TYPE_ALIAS(x32, u32, u32, 0),
217 ASSIGN_FETCH_TYPE_ALIAS(x64, u64, u64, 0),
218
219 ASSIGN_FETCH_TYPE_END
220 };
221
222 static inline void init_trace_uprobe_filter(struct trace_uprobe_filter *filter)
223 {
224 rwlock_init(&filter->rwlock);
225 filter->nr_systemwide = 0;
226 INIT_LIST_HEAD(&filter->perf_events);
227 }
228
229 static inline bool uprobe_filter_is_empty(struct trace_uprobe_filter *filter)
230 {
231 return !filter->nr_systemwide && list_empty(&filter->perf_events);
232 }
233
234 static inline bool is_ret_probe(struct trace_uprobe *tu)
235 {
236 return tu->consumer.ret_handler != NULL;
237 }
238
239 /*
240 * Allocate new trace_uprobe and initialize it (including uprobes).
241 */
242 static struct trace_uprobe *
243 alloc_trace_uprobe(const char *group, const char *event, int nargs, bool is_ret)
244 {
245 struct trace_uprobe *tu;
246
247 if (!event || !is_good_name(event))
248 return ERR_PTR(-EINVAL);
249
250 if (!group || !is_good_name(group))
251 return ERR_PTR(-EINVAL);
252
253 tu = kzalloc(SIZEOF_TRACE_UPROBE(nargs), GFP_KERNEL);
254 if (!tu)
255 return ERR_PTR(-ENOMEM);
256
257 tu->tp.call.class = &tu->tp.class;
258 tu->tp.call.name = kstrdup(event, GFP_KERNEL);
259 if (!tu->tp.call.name)
260 goto error;
261
262 tu->tp.class.system = kstrdup(group, GFP_KERNEL);
263 if (!tu->tp.class.system)
264 goto error;
265
266 INIT_LIST_HEAD(&tu->list);
267 INIT_LIST_HEAD(&tu->tp.files);
268 tu->consumer.handler = uprobe_dispatcher;
269 if (is_ret)
270 tu->consumer.ret_handler = uretprobe_dispatcher;
271 init_trace_uprobe_filter(&tu->filter);
272 return tu;
273
274 error:
275 kfree(tu->tp.call.name);
276 kfree(tu);
277
278 return ERR_PTR(-ENOMEM);
279 }
280
281 static void free_trace_uprobe(struct trace_uprobe *tu)
282 {
283 int i;
284
285 for (i = 0; i < tu->tp.nr_args; i++)
286 traceprobe_free_probe_arg(&tu->tp.args[i]);
287
288 iput(tu->inode);
289 kfree(tu->tp.call.class->system);
290 kfree(tu->tp.call.name);
291 kfree(tu->filename);
292 kfree(tu);
293 }
294
295 static struct trace_uprobe *find_probe_event(const char *event, const char *group)
296 {
297 struct trace_uprobe *tu;
298
299 list_for_each_entry(tu, &uprobe_list, list)
300 if (strcmp(trace_event_name(&tu->tp.call), event) == 0 &&
301 strcmp(tu->tp.call.class->system, group) == 0)
302 return tu;
303
304 return NULL;
305 }
306
307 /* Unregister a trace_uprobe and probe_event: call with locking uprobe_lock */
308 static int unregister_trace_uprobe(struct trace_uprobe *tu)
309 {
310 int ret;
311
312 ret = unregister_uprobe_event(tu);
313 if (ret)
314 return ret;
315
316 list_del(&tu->list);
317 free_trace_uprobe(tu);
318 return 0;
319 }
320
321 /* Register a trace_uprobe and probe_event */
322 static int register_trace_uprobe(struct trace_uprobe *tu)
323 {
324 struct trace_uprobe *old_tu;
325 int ret;
326
327 mutex_lock(&uprobe_lock);
328
329 /* register as an event */
330 old_tu = find_probe_event(trace_event_name(&tu->tp.call),
331 tu->tp.call.class->system);
332 if (old_tu) {
333 /* delete old event */
334 ret = unregister_trace_uprobe(old_tu);
335 if (ret)
336 goto end;
337 }
338
339 ret = register_uprobe_event(tu);
340 if (ret) {
341 pr_warn("Failed to register probe event(%d)\n", ret);
342 goto end;
343 }
344
345 list_add_tail(&tu->list, &uprobe_list);
346
347 end:
348 mutex_unlock(&uprobe_lock);
349
350 return ret;
351 }
352
353 /*
354 * Argument syntax:
355 * - Add uprobe: p|r[:[GRP/]EVENT] PATH:OFFSET [FETCHARGS]
356 *
357 * - Remove uprobe: -:[GRP/]EVENT
358 */
359 static int create_trace_uprobe(int argc, char **argv)
360 {
361 struct trace_uprobe *tu;
362 struct inode *inode;
363 char *arg, *event, *group, *filename;
364 char buf[MAX_EVENT_NAME_LEN];
365 struct path path;
366 unsigned long offset;
367 bool is_delete, is_return;
368 int i, ret;
369
370 inode = NULL;
371 ret = 0;
372 is_delete = false;
373 is_return = false;
374 event = NULL;
375 group = NULL;
376
377 /* argc must be >= 1 */
378 if (argv[0][0] == '-')
379 is_delete = true;
380 else if (argv[0][0] == 'r')
381 is_return = true;
382 else if (argv[0][0] != 'p') {
383 pr_info("Probe definition must be started with 'p', 'r' or '-'.\n");
384 return -EINVAL;
385 }
386
387 if (argv[0][1] == ':') {
388 event = &argv[0][2];
389 arg = strchr(event, '/');
390
391 if (arg) {
392 group = event;
393 event = arg + 1;
394 event[-1] = '\0';
395
396 if (strlen(group) == 0) {
397 pr_info("Group name is not specified\n");
398 return -EINVAL;
399 }
400 }
401 if (strlen(event) == 0) {
402 pr_info("Event name is not specified\n");
403 return -EINVAL;
404 }
405 }
406 if (!group)
407 group = UPROBE_EVENT_SYSTEM;
408
409 if (is_delete) {
410 int ret;
411
412 if (!event) {
413 pr_info("Delete command needs an event name.\n");
414 return -EINVAL;
415 }
416 mutex_lock(&uprobe_lock);
417 tu = find_probe_event(event, group);
418
419 if (!tu) {
420 mutex_unlock(&uprobe_lock);
421 pr_info("Event %s/%s doesn't exist.\n", group, event);
422 return -ENOENT;
423 }
424 /* delete an event */
425 ret = unregister_trace_uprobe(tu);
426 mutex_unlock(&uprobe_lock);
427 return ret;
428 }
429
430 if (argc < 2) {
431 pr_info("Probe point is not specified.\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(d_inode(path.dentry));
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 uprobes_fetch_type_table);
540 if (ret) {
541 pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
542 goto error;
543 }
544 }
545
546 ret = register_trace_uprobe(tu);
547 if (ret)
548 goto error;
549 return 0;
550
551 error:
552 free_trace_uprobe(tu);
553 return ret;
554
555 fail_address_parse:
556 iput(inode);
557
558 pr_info("Failed to parse address or file.\n");
559
560 return ret;
561 }
562
563 static int cleanup_all_probes(void)
564 {
565 struct trace_uprobe *tu;
566 int ret = 0;
567
568 mutex_lock(&uprobe_lock);
569 while (!list_empty(&uprobe_list)) {
570 tu = list_entry(uprobe_list.next, struct trace_uprobe, list);
571 ret = unregister_trace_uprobe(tu);
572 if (ret)
573 break;
574 }
575 mutex_unlock(&uprobe_lock);
576 return ret;
577 }
578
579 /* Probes listing interfaces */
580 static void *probes_seq_start(struct seq_file *m, loff_t *pos)
581 {
582 mutex_lock(&uprobe_lock);
583 return seq_list_start(&uprobe_list, *pos);
584 }
585
586 static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
587 {
588 return seq_list_next(v, &uprobe_list, pos);
589 }
590
591 static void probes_seq_stop(struct seq_file *m, void *v)
592 {
593 mutex_unlock(&uprobe_lock);
594 }
595
596 static int probes_seq_show(struct seq_file *m, void *v)
597 {
598 struct trace_uprobe *tu = v;
599 char c = is_ret_probe(tu) ? 'r' : 'p';
600 int i;
601
602 seq_printf(m, "%c:%s/%s", c, tu->tp.call.class->system,
603 trace_event_name(&tu->tp.call));
604 seq_printf(m, " %s:", tu->filename);
605
606 /* Don't print "0x (null)" when offset is 0 */
607 if (tu->offset) {
608 seq_printf(m, "0x%p", (void *)tu->offset);
609 } else {
610 switch (sizeof(void *)) {
611 case 4:
612 seq_printf(m, "0x00000000");
613 break;
614 case 8:
615 default:
616 seq_printf(m, "0x0000000000000000");
617 break;
618 }
619 }
620
621 for (i = 0; i < tu->tp.nr_args; i++)
622 seq_printf(m, " %s=%s", tu->tp.args[i].name, tu->tp.args[i].comm);
623
624 seq_putc(m, '\n');
625 return 0;
626 }
627
628 static const struct seq_operations probes_seq_op = {
629 .start = probes_seq_start,
630 .next = probes_seq_next,
631 .stop = probes_seq_stop,
632 .show = probes_seq_show
633 };
634
635 static int probes_open(struct inode *inode, struct file *file)
636 {
637 int ret;
638
639 if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
640 ret = cleanup_all_probes();
641 if (ret)
642 return ret;
643 }
644
645 return seq_open(file, &probes_seq_op);
646 }
647
648 static ssize_t probes_write(struct file *file, const char __user *buffer,
649 size_t count, loff_t *ppos)
650 {
651 return traceprobe_probes_write(file, buffer, count, ppos, create_trace_uprobe);
652 }
653
654 static const struct file_operations uprobe_events_ops = {
655 .owner = THIS_MODULE,
656 .open = probes_open,
657 .read = seq_read,
658 .llseek = seq_lseek,
659 .release = seq_release,
660 .write = probes_write,
661 };
662
663 /* Probes profiling interfaces */
664 static int probes_profile_seq_show(struct seq_file *m, void *v)
665 {
666 struct trace_uprobe *tu = v;
667
668 seq_printf(m, " %s %-44s %15lu\n", tu->filename,
669 trace_event_name(&tu->tp.call), tu->nhit);
670 return 0;
671 }
672
673 static const struct seq_operations profile_seq_op = {
674 .start = probes_seq_start,
675 .next = probes_seq_next,
676 .stop = probes_seq_stop,
677 .show = probes_profile_seq_show
678 };
679
680 static int profile_open(struct inode *inode, struct file *file)
681 {
682 return seq_open(file, &profile_seq_op);
683 }
684
685 static const struct file_operations uprobe_profile_ops = {
686 .owner = THIS_MODULE,
687 .open = profile_open,
688 .read = seq_read,
689 .llseek = seq_lseek,
690 .release = seq_release,
691 };
692
693 struct uprobe_cpu_buffer {
694 struct mutex mutex;
695 void *buf;
696 };
697 static struct uprobe_cpu_buffer __percpu *uprobe_cpu_buffer;
698 static int uprobe_buffer_refcnt;
699
700 static int uprobe_buffer_init(void)
701 {
702 int cpu, err_cpu;
703
704 uprobe_cpu_buffer = alloc_percpu(struct uprobe_cpu_buffer);
705 if (uprobe_cpu_buffer == NULL)
706 return -ENOMEM;
707
708 for_each_possible_cpu(cpu) {
709 struct page *p = alloc_pages_node(cpu_to_node(cpu),
710 GFP_KERNEL, 0);
711 if (p == NULL) {
712 err_cpu = cpu;
713 goto err;
714 }
715 per_cpu_ptr(uprobe_cpu_buffer, cpu)->buf = page_address(p);
716 mutex_init(&per_cpu_ptr(uprobe_cpu_buffer, cpu)->mutex);
717 }
718
719 return 0;
720
721 err:
722 for_each_possible_cpu(cpu) {
723 if (cpu == err_cpu)
724 break;
725 free_page((unsigned long)per_cpu_ptr(uprobe_cpu_buffer, cpu)->buf);
726 }
727
728 free_percpu(uprobe_cpu_buffer);
729 return -ENOMEM;
730 }
731
732 static int uprobe_buffer_enable(void)
733 {
734 int ret = 0;
735
736 BUG_ON(!mutex_is_locked(&event_mutex));
737
738 if (uprobe_buffer_refcnt++ == 0) {
739 ret = uprobe_buffer_init();
740 if (ret < 0)
741 uprobe_buffer_refcnt--;
742 }
743
744 return ret;
745 }
746
747 static void uprobe_buffer_disable(void)
748 {
749 int cpu;
750
751 BUG_ON(!mutex_is_locked(&event_mutex));
752
753 if (--uprobe_buffer_refcnt == 0) {
754 for_each_possible_cpu(cpu)
755 free_page((unsigned long)per_cpu_ptr(uprobe_cpu_buffer,
756 cpu)->buf);
757
758 free_percpu(uprobe_cpu_buffer);
759 uprobe_cpu_buffer = NULL;
760 }
761 }
762
763 static struct uprobe_cpu_buffer *uprobe_buffer_get(void)
764 {
765 struct uprobe_cpu_buffer *ucb;
766 int cpu;
767
768 cpu = raw_smp_processor_id();
769 ucb = per_cpu_ptr(uprobe_cpu_buffer, cpu);
770
771 /*
772 * Use per-cpu buffers for fastest access, but we might migrate
773 * so the mutex makes sure we have sole access to it.
774 */
775 mutex_lock(&ucb->mutex);
776
777 return ucb;
778 }
779
780 static void uprobe_buffer_put(struct uprobe_cpu_buffer *ucb)
781 {
782 mutex_unlock(&ucb->mutex);
783 }
784
785 static void __uprobe_trace_func(struct trace_uprobe *tu,
786 unsigned long func, struct pt_regs *regs,
787 struct uprobe_cpu_buffer *ucb, int dsize,
788 struct trace_event_file *trace_file)
789 {
790 struct uprobe_trace_entry_head *entry;
791 struct ring_buffer_event *event;
792 struct ring_buffer *buffer;
793 void *data;
794 int size, esize;
795 struct trace_event_call *call = &tu->tp.call;
796
797 WARN_ON(call != trace_file->event_call);
798
799 if (WARN_ON_ONCE(tu->tp.size + dsize > PAGE_SIZE))
800 return;
801
802 if (trace_trigger_soft_disabled(trace_file))
803 return;
804
805 esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
806 size = esize + tu->tp.size + dsize;
807 event = trace_event_buffer_lock_reserve(&buffer, trace_file,
808 call->event.type, size, 0, 0);
809 if (!event)
810 return;
811
812 entry = ring_buffer_event_data(event);
813 if (is_ret_probe(tu)) {
814 entry->vaddr[0] = func;
815 entry->vaddr[1] = instruction_pointer(regs);
816 data = DATAOF_TRACE_ENTRY(entry, true);
817 } else {
818 entry->vaddr[0] = instruction_pointer(regs);
819 data = DATAOF_TRACE_ENTRY(entry, false);
820 }
821
822 memcpy(data, ucb->buf, tu->tp.size + dsize);
823
824 event_trigger_unlock_commit(trace_file, buffer, event, entry, 0, 0);
825 }
826
827 /* uprobe handler */
828 static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs,
829 struct uprobe_cpu_buffer *ucb, int dsize)
830 {
831 struct event_file_link *link;
832
833 if (is_ret_probe(tu))
834 return 0;
835
836 rcu_read_lock();
837 list_for_each_entry_rcu(link, &tu->tp.files, list)
838 __uprobe_trace_func(tu, 0, regs, ucb, dsize, link->file);
839 rcu_read_unlock();
840
841 return 0;
842 }
843
844 static void uretprobe_trace_func(struct trace_uprobe *tu, unsigned long func,
845 struct pt_regs *regs,
846 struct uprobe_cpu_buffer *ucb, int dsize)
847 {
848 struct event_file_link *link;
849
850 rcu_read_lock();
851 list_for_each_entry_rcu(link, &tu->tp.files, list)
852 __uprobe_trace_func(tu, func, regs, ucb, dsize, link->file);
853 rcu_read_unlock();
854 }
855
856 /* Event entry printers */
857 static enum print_line_t
858 print_uprobe_event(struct trace_iterator *iter, int flags, struct trace_event *event)
859 {
860 struct uprobe_trace_entry_head *entry;
861 struct trace_seq *s = &iter->seq;
862 struct trace_uprobe *tu;
863 u8 *data;
864 int i;
865
866 entry = (struct uprobe_trace_entry_head *)iter->ent;
867 tu = container_of(event, struct trace_uprobe, tp.call.event);
868
869 if (is_ret_probe(tu)) {
870 trace_seq_printf(s, "%s: (0x%lx <- 0x%lx)",
871 trace_event_name(&tu->tp.call),
872 entry->vaddr[1], entry->vaddr[0]);
873 data = DATAOF_TRACE_ENTRY(entry, true);
874 } else {
875 trace_seq_printf(s, "%s: (0x%lx)",
876 trace_event_name(&tu->tp.call),
877 entry->vaddr[0]);
878 data = DATAOF_TRACE_ENTRY(entry, false);
879 }
880
881 for (i = 0; i < tu->tp.nr_args; i++) {
882 struct probe_arg *parg = &tu->tp.args[i];
883
884 if (!parg->type->print(s, parg->name, data + parg->offset, entry))
885 goto out;
886 }
887
888 trace_seq_putc(s, '\n');
889
890 out:
891 return trace_handle_return(s);
892 }
893
894 typedef bool (*filter_func_t)(struct uprobe_consumer *self,
895 enum uprobe_filter_ctx ctx,
896 struct mm_struct *mm);
897
898 static int
899 probe_event_enable(struct trace_uprobe *tu, struct trace_event_file *file,
900 filter_func_t filter)
901 {
902 bool enabled = trace_probe_is_enabled(&tu->tp);
903 struct event_file_link *link = NULL;
904 int ret;
905
906 if (file) {
907 if (tu->tp.flags & TP_FLAG_PROFILE)
908 return -EINTR;
909
910 link = kmalloc(sizeof(*link), GFP_KERNEL);
911 if (!link)
912 return -ENOMEM;
913
914 link->file = file;
915 list_add_tail_rcu(&link->list, &tu->tp.files);
916
917 tu->tp.flags |= TP_FLAG_TRACE;
918 } else {
919 if (tu->tp.flags & TP_FLAG_TRACE)
920 return -EINTR;
921
922 tu->tp.flags |= TP_FLAG_PROFILE;
923 }
924
925 WARN_ON(!uprobe_filter_is_empty(&tu->filter));
926
927 if (enabled)
928 return 0;
929
930 ret = uprobe_buffer_enable();
931 if (ret)
932 goto err_flags;
933
934 tu->consumer.filter = filter;
935 ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
936 if (ret)
937 goto err_buffer;
938
939 return 0;
940
941 err_buffer:
942 uprobe_buffer_disable();
943
944 err_flags:
945 if (file) {
946 list_del(&link->list);
947 kfree(link);
948 tu->tp.flags &= ~TP_FLAG_TRACE;
949 } else {
950 tu->tp.flags &= ~TP_FLAG_PROFILE;
951 }
952 return ret;
953 }
954
955 static void
956 probe_event_disable(struct trace_uprobe *tu, struct trace_event_file *file)
957 {
958 if (!trace_probe_is_enabled(&tu->tp))
959 return;
960
961 if (file) {
962 struct event_file_link *link;
963
964 link = find_event_file_link(&tu->tp, file);
965 if (!link)
966 return;
967
968 list_del_rcu(&link->list);
969 /* synchronize with u{,ret}probe_trace_func */
970 synchronize_sched();
971 kfree(link);
972
973 if (!list_empty(&tu->tp.files))
974 return;
975 }
976
977 WARN_ON(!uprobe_filter_is_empty(&tu->filter));
978
979 uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
980 tu->tp.flags &= file ? ~TP_FLAG_TRACE : ~TP_FLAG_PROFILE;
981
982 uprobe_buffer_disable();
983 }
984
985 static int uprobe_event_define_fields(struct trace_event_call *event_call)
986 {
987 int ret, i, size;
988 struct uprobe_trace_entry_head field;
989 struct trace_uprobe *tu = event_call->data;
990
991 if (is_ret_probe(tu)) {
992 DEFINE_FIELD(unsigned long, vaddr[0], FIELD_STRING_FUNC, 0);
993 DEFINE_FIELD(unsigned long, vaddr[1], FIELD_STRING_RETIP, 0);
994 size = SIZEOF_TRACE_ENTRY(true);
995 } else {
996 DEFINE_FIELD(unsigned long, vaddr[0], FIELD_STRING_IP, 0);
997 size = SIZEOF_TRACE_ENTRY(false);
998 }
999 /* Set argument names as fields */
1000 for (i = 0; i < tu->tp.nr_args; i++) {
1001 struct probe_arg *parg = &tu->tp.args[i];
1002
1003 ret = trace_define_field(event_call, parg->type->fmttype,
1004 parg->name, size + parg->offset,
1005 parg->type->size, parg->type->is_signed,
1006 FILTER_OTHER);
1007
1008 if (ret)
1009 return ret;
1010 }
1011 return 0;
1012 }
1013
1014 #ifdef CONFIG_PERF_EVENTS
1015 static bool
1016 __uprobe_perf_filter(struct trace_uprobe_filter *filter, struct mm_struct *mm)
1017 {
1018 struct perf_event *event;
1019
1020 if (filter->nr_systemwide)
1021 return true;
1022
1023 list_for_each_entry(event, &filter->perf_events, hw.tp_list) {
1024 if (event->hw.target->mm == mm)
1025 return true;
1026 }
1027
1028 return false;
1029 }
1030
1031 static inline bool
1032 uprobe_filter_event(struct trace_uprobe *tu, struct perf_event *event)
1033 {
1034 return __uprobe_perf_filter(&tu->filter, event->hw.target->mm);
1035 }
1036
1037 static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event)
1038 {
1039 bool done;
1040
1041 write_lock(&tu->filter.rwlock);
1042 if (event->hw.target) {
1043 list_del(&event->hw.tp_list);
1044 done = tu->filter.nr_systemwide ||
1045 (event->hw.target->flags & PF_EXITING) ||
1046 uprobe_filter_event(tu, event);
1047 } else {
1048 tu->filter.nr_systemwide--;
1049 done = tu->filter.nr_systemwide;
1050 }
1051 write_unlock(&tu->filter.rwlock);
1052
1053 if (!done)
1054 return uprobe_apply(tu->inode, tu->offset, &tu->consumer, false);
1055
1056 return 0;
1057 }
1058
1059 static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event)
1060 {
1061 bool done;
1062 int err;
1063
1064 write_lock(&tu->filter.rwlock);
1065 if (event->hw.target) {
1066 /*
1067 * event->parent != NULL means copy_process(), we can avoid
1068 * uprobe_apply(). current->mm must be probed and we can rely
1069 * on dup_mmap() which preserves the already installed bp's.
1070 *
1071 * attr.enable_on_exec means that exec/mmap will install the
1072 * breakpoints we need.
1073 */
1074 done = tu->filter.nr_systemwide ||
1075 event->parent || event->attr.enable_on_exec ||
1076 uprobe_filter_event(tu, event);
1077 list_add(&event->hw.tp_list, &tu->filter.perf_events);
1078 } else {
1079 done = tu->filter.nr_systemwide;
1080 tu->filter.nr_systemwide++;
1081 }
1082 write_unlock(&tu->filter.rwlock);
1083
1084 err = 0;
1085 if (!done) {
1086 err = uprobe_apply(tu->inode, tu->offset, &tu->consumer, true);
1087 if (err)
1088 uprobe_perf_close(tu, event);
1089 }
1090 return err;
1091 }
1092
1093 static bool uprobe_perf_filter(struct uprobe_consumer *uc,
1094 enum uprobe_filter_ctx ctx, struct mm_struct *mm)
1095 {
1096 struct trace_uprobe *tu;
1097 int ret;
1098
1099 tu = container_of(uc, struct trace_uprobe, consumer);
1100 read_lock(&tu->filter.rwlock);
1101 ret = __uprobe_perf_filter(&tu->filter, mm);
1102 read_unlock(&tu->filter.rwlock);
1103
1104 return ret;
1105 }
1106
1107 static void __uprobe_perf_func(struct trace_uprobe *tu,
1108 unsigned long func, struct pt_regs *regs,
1109 struct uprobe_cpu_buffer *ucb, int dsize)
1110 {
1111 struct trace_event_call *call = &tu->tp.call;
1112 struct uprobe_trace_entry_head *entry;
1113 struct bpf_prog *prog = call->prog;
1114 struct hlist_head *head;
1115 void *data;
1116 int size, esize;
1117 int rctx;
1118
1119 if (prog && !trace_call_bpf(prog, regs))
1120 return;
1121
1122 esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
1123
1124 size = esize + tu->tp.size + dsize;
1125 size = ALIGN(size + sizeof(u32), sizeof(u64)) - sizeof(u32);
1126 if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, "profile buffer not large enough"))
1127 return;
1128
1129 preempt_disable();
1130 head = this_cpu_ptr(call->perf_events);
1131 if (hlist_empty(head))
1132 goto out;
1133
1134 entry = perf_trace_buf_alloc(size, NULL, &rctx);
1135 if (!entry)
1136 goto out;
1137
1138 if (is_ret_probe(tu)) {
1139 entry->vaddr[0] = func;
1140 entry->vaddr[1] = instruction_pointer(regs);
1141 data = DATAOF_TRACE_ENTRY(entry, true);
1142 } else {
1143 entry->vaddr[0] = instruction_pointer(regs);
1144 data = DATAOF_TRACE_ENTRY(entry, false);
1145 }
1146
1147 memcpy(data, ucb->buf, tu->tp.size + dsize);
1148
1149 if (size - esize > tu->tp.size + dsize) {
1150 int len = tu->tp.size + dsize;
1151
1152 memset(data + len, 0, size - esize - len);
1153 }
1154
1155 perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
1156 head, NULL);
1157 out:
1158 preempt_enable();
1159 }
1160
1161 /* uprobe profile handler */
1162 static int uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs,
1163 struct uprobe_cpu_buffer *ucb, int dsize)
1164 {
1165 if (!uprobe_perf_filter(&tu->consumer, 0, current->mm))
1166 return UPROBE_HANDLER_REMOVE;
1167
1168 if (!is_ret_probe(tu))
1169 __uprobe_perf_func(tu, 0, regs, ucb, dsize);
1170 return 0;
1171 }
1172
1173 static void uretprobe_perf_func(struct trace_uprobe *tu, unsigned long func,
1174 struct pt_regs *regs,
1175 struct uprobe_cpu_buffer *ucb, int dsize)
1176 {
1177 __uprobe_perf_func(tu, func, regs, ucb, dsize);
1178 }
1179 #endif /* CONFIG_PERF_EVENTS */
1180
1181 static int
1182 trace_uprobe_register(struct trace_event_call *event, enum trace_reg type,
1183 void *data)
1184 {
1185 struct trace_uprobe *tu = event->data;
1186 struct trace_event_file *file = data;
1187
1188 switch (type) {
1189 case TRACE_REG_REGISTER:
1190 return probe_event_enable(tu, file, NULL);
1191
1192 case TRACE_REG_UNREGISTER:
1193 probe_event_disable(tu, file);
1194 return 0;
1195
1196 #ifdef CONFIG_PERF_EVENTS
1197 case TRACE_REG_PERF_REGISTER:
1198 return probe_event_enable(tu, NULL, uprobe_perf_filter);
1199
1200 case TRACE_REG_PERF_UNREGISTER:
1201 probe_event_disable(tu, NULL);
1202 return 0;
1203
1204 case TRACE_REG_PERF_OPEN:
1205 return uprobe_perf_open(tu, data);
1206
1207 case TRACE_REG_PERF_CLOSE:
1208 return uprobe_perf_close(tu, data);
1209
1210 #endif
1211 default:
1212 return 0;
1213 }
1214 return 0;
1215 }
1216
1217 static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs)
1218 {
1219 struct trace_uprobe *tu;
1220 struct uprobe_dispatch_data udd;
1221 struct uprobe_cpu_buffer *ucb;
1222 int dsize, esize;
1223 int ret = 0;
1224
1225
1226 tu = container_of(con, struct trace_uprobe, consumer);
1227 tu->nhit++;
1228
1229 udd.tu = tu;
1230 udd.bp_addr = instruction_pointer(regs);
1231
1232 current->utask->vaddr = (unsigned long) &udd;
1233
1234 if (WARN_ON_ONCE(!uprobe_cpu_buffer))
1235 return 0;
1236
1237 dsize = __get_data_size(&tu->tp, regs);
1238 esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
1239
1240 ucb = uprobe_buffer_get();
1241 store_trace_args(esize, &tu->tp, regs, ucb->buf, dsize);
1242
1243 if (tu->tp.flags & TP_FLAG_TRACE)
1244 ret |= uprobe_trace_func(tu, regs, ucb, dsize);
1245
1246 #ifdef CONFIG_PERF_EVENTS
1247 if (tu->tp.flags & TP_FLAG_PROFILE)
1248 ret |= uprobe_perf_func(tu, regs, ucb, dsize);
1249 #endif
1250 uprobe_buffer_put(ucb);
1251 return ret;
1252 }
1253
1254 static int uretprobe_dispatcher(struct uprobe_consumer *con,
1255 unsigned long func, struct pt_regs *regs)
1256 {
1257 struct trace_uprobe *tu;
1258 struct uprobe_dispatch_data udd;
1259 struct uprobe_cpu_buffer *ucb;
1260 int dsize, esize;
1261
1262 tu = container_of(con, struct trace_uprobe, consumer);
1263
1264 udd.tu = tu;
1265 udd.bp_addr = func;
1266
1267 current->utask->vaddr = (unsigned long) &udd;
1268
1269 if (WARN_ON_ONCE(!uprobe_cpu_buffer))
1270 return 0;
1271
1272 dsize = __get_data_size(&tu->tp, regs);
1273 esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
1274
1275 ucb = uprobe_buffer_get();
1276 store_trace_args(esize, &tu->tp, regs, ucb->buf, dsize);
1277
1278 if (tu->tp.flags & TP_FLAG_TRACE)
1279 uretprobe_trace_func(tu, func, regs, ucb, dsize);
1280
1281 #ifdef CONFIG_PERF_EVENTS
1282 if (tu->tp.flags & TP_FLAG_PROFILE)
1283 uretprobe_perf_func(tu, func, regs, ucb, dsize);
1284 #endif
1285 uprobe_buffer_put(ucb);
1286 return 0;
1287 }
1288
1289 static struct trace_event_functions uprobe_funcs = {
1290 .trace = print_uprobe_event
1291 };
1292
1293 static int register_uprobe_event(struct trace_uprobe *tu)
1294 {
1295 struct trace_event_call *call = &tu->tp.call;
1296 int ret;
1297
1298 /* Initialize trace_event_call */
1299 INIT_LIST_HEAD(&call->class->fields);
1300 call->event.funcs = &uprobe_funcs;
1301 call->class->define_fields = uprobe_event_define_fields;
1302
1303 if (set_print_fmt(&tu->tp, is_ret_probe(tu)) < 0)
1304 return -ENOMEM;
1305
1306 ret = register_trace_event(&call->event);
1307 if (!ret) {
1308 kfree(call->print_fmt);
1309 return -ENODEV;
1310 }
1311
1312 call->flags = TRACE_EVENT_FL_UPROBE;
1313 call->class->reg = trace_uprobe_register;
1314 call->data = tu;
1315 ret = trace_add_event_call(call);
1316
1317 if (ret) {
1318 pr_info("Failed to register uprobe event: %s\n",
1319 trace_event_name(call));
1320 kfree(call->print_fmt);
1321 unregister_trace_event(&call->event);
1322 }
1323
1324 return ret;
1325 }
1326
1327 static int unregister_uprobe_event(struct trace_uprobe *tu)
1328 {
1329 int ret;
1330
1331 /* tu->event is unregistered in trace_remove_event_call() */
1332 ret = trace_remove_event_call(&tu->tp.call);
1333 if (ret)
1334 return ret;
1335 kfree(tu->tp.call.print_fmt);
1336 tu->tp.call.print_fmt = NULL;
1337 return 0;
1338 }
1339
1340 /* Make a trace interface for controling probe points */
1341 static __init int init_uprobe_trace(void)
1342 {
1343 struct dentry *d_tracer;
1344
1345 d_tracer = tracing_init_dentry();
1346 if (IS_ERR(d_tracer))
1347 return 0;
1348
1349 trace_create_file("uprobe_events", 0644, d_tracer,
1350 NULL, &uprobe_events_ops);
1351 /* Profile interface */
1352 trace_create_file("uprobe_profile", 0444, d_tracer,
1353 NULL, &uprobe_profile_ops);
1354 return 0;
1355 }
1356
1357 fs_initcall(init_uprobe_trace);
Linux kernel - Deliverables
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