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[deliverable/linux.git] / kernel / trace / trace_kprobe.c
1 /*
2 * kprobe based kernel tracer
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 #include <linux/kprobes.h>
23 #include <linux/seq_file.h>
24 #include <linux/slab.h>
25 #include <linux/smp.h>
26 #include <linux/debugfs.h>
27 #include <linux/types.h>
28 #include <linux/string.h>
29 #include <linux/ctype.h>
30 #include <linux/ptrace.h>
31 #include <linux/perf_event.h>
32
33 #include "trace.h"
34 #include "trace_output.h"
35
36 #define MAX_TRACE_ARGS 128
37 #define MAX_ARGSTR_LEN 63
38 #define MAX_EVENT_NAME_LEN 64
39 #define KPROBE_EVENT_SYSTEM "kprobes"
40
41 /* currently, trace_kprobe only supports X86. */
42
43 struct fetch_func {
44 unsigned long (*func)(struct pt_regs *, void *);
45 void *data;
46 };
47
48 static __kprobes unsigned long call_fetch(struct fetch_func *f,
49 struct pt_regs *regs)
50 {
51 return f->func(regs, f->data);
52 }
53
54 /* fetch handlers */
55 static __kprobes unsigned long fetch_register(struct pt_regs *regs,
56 void *offset)
57 {
58 return regs_get_register(regs, (unsigned int)((unsigned long)offset));
59 }
60
61 static __kprobes unsigned long fetch_stack(struct pt_regs *regs,
62 void *num)
63 {
64 return regs_get_kernel_stack_nth(regs,
65 (unsigned int)((unsigned long)num));
66 }
67
68 static __kprobes unsigned long fetch_memory(struct pt_regs *regs, void *addr)
69 {
70 unsigned long retval;
71
72 if (probe_kernel_address(addr, retval))
73 return 0;
74 return retval;
75 }
76
77 static __kprobes unsigned long fetch_argument(struct pt_regs *regs, void *num)
78 {
79 return regs_get_argument_nth(regs, (unsigned int)((unsigned long)num));
80 }
81
82 static __kprobes unsigned long fetch_retvalue(struct pt_regs *regs,
83 void *dummy)
84 {
85 return regs_return_value(regs);
86 }
87
88 static __kprobes unsigned long fetch_ip(struct pt_regs *regs, void *dummy)
89 {
90 return instruction_pointer(regs);
91 }
92
93 static __kprobes unsigned long fetch_stack_address(struct pt_regs *regs,
94 void *dummy)
95 {
96 return kernel_stack_pointer(regs);
97 }
98
99 /* Memory fetching by symbol */
100 struct symbol_cache {
101 char *symbol;
102 long offset;
103 unsigned long addr;
104 };
105
106 static unsigned long update_symbol_cache(struct symbol_cache *sc)
107 {
108 sc->addr = (unsigned long)kallsyms_lookup_name(sc->symbol);
109 if (sc->addr)
110 sc->addr += sc->offset;
111 return sc->addr;
112 }
113
114 static void free_symbol_cache(struct symbol_cache *sc)
115 {
116 kfree(sc->symbol);
117 kfree(sc);
118 }
119
120 static struct symbol_cache *alloc_symbol_cache(const char *sym, long offset)
121 {
122 struct symbol_cache *sc;
123
124 if (!sym || strlen(sym) == 0)
125 return NULL;
126 sc = kzalloc(sizeof(struct symbol_cache), GFP_KERNEL);
127 if (!sc)
128 return NULL;
129
130 sc->symbol = kstrdup(sym, GFP_KERNEL);
131 if (!sc->symbol) {
132 kfree(sc);
133 return NULL;
134 }
135 sc->offset = offset;
136
137 update_symbol_cache(sc);
138 return sc;
139 }
140
141 static __kprobes unsigned long fetch_symbol(struct pt_regs *regs, void *data)
142 {
143 struct symbol_cache *sc = data;
144
145 if (sc->addr)
146 return fetch_memory(regs, (void *)sc->addr);
147 else
148 return 0;
149 }
150
151 /* Special indirect memory access interface */
152 struct indirect_fetch_data {
153 struct fetch_func orig;
154 long offset;
155 };
156
157 static __kprobes unsigned long fetch_indirect(struct pt_regs *regs, void *data)
158 {
159 struct indirect_fetch_data *ind = data;
160 unsigned long addr;
161
162 addr = call_fetch(&ind->orig, regs);
163 if (addr) {
164 addr += ind->offset;
165 return fetch_memory(regs, (void *)addr);
166 } else
167 return 0;
168 }
169
170 static __kprobes void free_indirect_fetch_data(struct indirect_fetch_data *data)
171 {
172 if (data->orig.func == fetch_indirect)
173 free_indirect_fetch_data(data->orig.data);
174 else if (data->orig.func == fetch_symbol)
175 free_symbol_cache(data->orig.data);
176 kfree(data);
177 }
178
179 /**
180 * Kprobe tracer core functions
181 */
182
183 struct probe_arg {
184 struct fetch_func fetch;
185 const char *name;
186 };
187
188 /* Flags for trace_probe */
189 #define TP_FLAG_TRACE 1
190 #define TP_FLAG_PROFILE 2
191
192 struct trace_probe {
193 struct list_head list;
194 struct kretprobe rp; /* Use rp.kp for kprobe use */
195 unsigned long nhit;
196 unsigned int flags; /* For TP_FLAG_* */
197 const char *symbol; /* symbol name */
198 struct ftrace_event_call call;
199 struct trace_event event;
200 unsigned int nr_args;
201 struct probe_arg args[];
202 };
203
204 #define SIZEOF_TRACE_PROBE(n) \
205 (offsetof(struct trace_probe, args) + \
206 (sizeof(struct probe_arg) * (n)))
207
208 static __kprobes int probe_is_return(struct trace_probe *tp)
209 {
210 return tp->rp.handler != NULL;
211 }
212
213 static __kprobes const char *probe_symbol(struct trace_probe *tp)
214 {
215 return tp->symbol ? tp->symbol : "unknown";
216 }
217
218 static int probe_arg_string(char *buf, size_t n, struct fetch_func *ff)
219 {
220 int ret = -EINVAL;
221
222 if (ff->func == fetch_argument)
223 ret = snprintf(buf, n, "a%lu", (unsigned long)ff->data);
224 else if (ff->func == fetch_register) {
225 const char *name;
226 name = regs_query_register_name((unsigned int)((long)ff->data));
227 ret = snprintf(buf, n, "%%%s", name);
228 } else if (ff->func == fetch_stack)
229 ret = snprintf(buf, n, "s%lu", (unsigned long)ff->data);
230 else if (ff->func == fetch_memory)
231 ret = snprintf(buf, n, "@0x%p", ff->data);
232 else if (ff->func == fetch_symbol) {
233 struct symbol_cache *sc = ff->data;
234 ret = snprintf(buf, n, "@%s%+ld", sc->symbol, sc->offset);
235 } else if (ff->func == fetch_retvalue)
236 ret = snprintf(buf, n, "rv");
237 else if (ff->func == fetch_ip)
238 ret = snprintf(buf, n, "ra");
239 else if (ff->func == fetch_stack_address)
240 ret = snprintf(buf, n, "sa");
241 else if (ff->func == fetch_indirect) {
242 struct indirect_fetch_data *id = ff->data;
243 size_t l = 0;
244 ret = snprintf(buf, n, "%+ld(", id->offset);
245 if (ret >= n)
246 goto end;
247 l += ret;
248 ret = probe_arg_string(buf + l, n - l, &id->orig);
249 if (ret < 0)
250 goto end;
251 l += ret;
252 ret = snprintf(buf + l, n - l, ")");
253 ret += l;
254 }
255 end:
256 if (ret >= n)
257 return -ENOSPC;
258 return ret;
259 }
260
261 static int register_probe_event(struct trace_probe *tp);
262 static void unregister_probe_event(struct trace_probe *tp);
263
264 static DEFINE_MUTEX(probe_lock);
265 static LIST_HEAD(probe_list);
266
267 static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
268 static int kretprobe_dispatcher(struct kretprobe_instance *ri,
269 struct pt_regs *regs);
270
271 /*
272 * Allocate new trace_probe and initialize it (including kprobes).
273 */
274 static struct trace_probe *alloc_trace_probe(const char *group,
275 const char *event,
276 void *addr,
277 const char *symbol,
278 unsigned long offs,
279 int nargs, int is_return)
280 {
281 struct trace_probe *tp;
282
283 tp = kzalloc(SIZEOF_TRACE_PROBE(nargs), GFP_KERNEL);
284 if (!tp)
285 return ERR_PTR(-ENOMEM);
286
287 if (symbol) {
288 tp->symbol = kstrdup(symbol, GFP_KERNEL);
289 if (!tp->symbol)
290 goto error;
291 tp->rp.kp.symbol_name = tp->symbol;
292 tp->rp.kp.offset = offs;
293 } else
294 tp->rp.kp.addr = addr;
295
296 if (is_return)
297 tp->rp.handler = kretprobe_dispatcher;
298 else
299 tp->rp.kp.pre_handler = kprobe_dispatcher;
300
301 if (!event)
302 goto error;
303 tp->call.name = kstrdup(event, GFP_KERNEL);
304 if (!tp->call.name)
305 goto error;
306
307 if (!group)
308 goto error;
309 tp->call.system = kstrdup(group, GFP_KERNEL);
310 if (!tp->call.system)
311 goto error;
312
313 INIT_LIST_HEAD(&tp->list);
314 return tp;
315 error:
316 kfree(tp->call.name);
317 kfree(tp->symbol);
318 kfree(tp);
319 return ERR_PTR(-ENOMEM);
320 }
321
322 static void free_probe_arg(struct probe_arg *arg)
323 {
324 if (arg->fetch.func == fetch_symbol)
325 free_symbol_cache(arg->fetch.data);
326 else if (arg->fetch.func == fetch_indirect)
327 free_indirect_fetch_data(arg->fetch.data);
328 kfree(arg->name);
329 }
330
331 static void free_trace_probe(struct trace_probe *tp)
332 {
333 int i;
334
335 for (i = 0; i < tp->nr_args; i++)
336 free_probe_arg(&tp->args[i]);
337
338 kfree(tp->call.system);
339 kfree(tp->call.name);
340 kfree(tp->symbol);
341 kfree(tp);
342 }
343
344 static struct trace_probe *find_probe_event(const char *event)
345 {
346 struct trace_probe *tp;
347
348 list_for_each_entry(tp, &probe_list, list)
349 if (!strcmp(tp->call.name, event))
350 return tp;
351 return NULL;
352 }
353
354 /* Unregister a trace_probe and probe_event: call with locking probe_lock */
355 static void unregister_trace_probe(struct trace_probe *tp)
356 {
357 if (probe_is_return(tp))
358 unregister_kretprobe(&tp->rp);
359 else
360 unregister_kprobe(&tp->rp.kp);
361 list_del(&tp->list);
362 unregister_probe_event(tp);
363 }
364
365 /* Register a trace_probe and probe_event */
366 static int register_trace_probe(struct trace_probe *tp)
367 {
368 struct trace_probe *old_tp;
369 int ret;
370
371 mutex_lock(&probe_lock);
372
373 /* register as an event */
374 old_tp = find_probe_event(tp->call.name);
375 if (old_tp) {
376 /* delete old event */
377 unregister_trace_probe(old_tp);
378 free_trace_probe(old_tp);
379 }
380 ret = register_probe_event(tp);
381 if (ret) {
382 pr_warning("Faild to register probe event(%d)\n", ret);
383 goto end;
384 }
385
386 tp->rp.kp.flags |= KPROBE_FLAG_DISABLED;
387 if (probe_is_return(tp))
388 ret = register_kretprobe(&tp->rp);
389 else
390 ret = register_kprobe(&tp->rp.kp);
391
392 if (ret) {
393 pr_warning("Could not insert probe(%d)\n", ret);
394 if (ret == -EILSEQ) {
395 pr_warning("Probing address(0x%p) is not an "
396 "instruction boundary.\n",
397 tp->rp.kp.addr);
398 ret = -EINVAL;
399 }
400 unregister_probe_event(tp);
401 } else
402 list_add_tail(&tp->list, &probe_list);
403 end:
404 mutex_unlock(&probe_lock);
405 return ret;
406 }
407
408 /* Split symbol and offset. */
409 static int split_symbol_offset(char *symbol, unsigned long *offset)
410 {
411 char *tmp;
412 int ret;
413
414 if (!offset)
415 return -EINVAL;
416
417 tmp = strchr(symbol, '+');
418 if (tmp) {
419 /* skip sign because strict_strtol doesn't accept '+' */
420 ret = strict_strtoul(tmp + 1, 0, offset);
421 if (ret)
422 return ret;
423 *tmp = '\0';
424 } else
425 *offset = 0;
426 return 0;
427 }
428
429 #define PARAM_MAX_ARGS 16
430 #define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
431
432 static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
433 {
434 int ret = 0;
435 unsigned long param;
436 long offset;
437 char *tmp;
438
439 switch (arg[0]) {
440 case 'a': /* argument */
441 ret = strict_strtoul(arg + 1, 10, &param);
442 if (ret || param > PARAM_MAX_ARGS)
443 ret = -EINVAL;
444 else {
445 ff->func = fetch_argument;
446 ff->data = (void *)param;
447 }
448 break;
449 case 'r': /* retval or retaddr */
450 if (is_return && arg[1] == 'v') {
451 ff->func = fetch_retvalue;
452 ff->data = NULL;
453 } else if (is_return && arg[1] == 'a') {
454 ff->func = fetch_ip;
455 ff->data = NULL;
456 } else
457 ret = -EINVAL;
458 break;
459 case '%': /* named register */
460 ret = regs_query_register_offset(arg + 1);
461 if (ret >= 0) {
462 ff->func = fetch_register;
463 ff->data = (void *)(unsigned long)ret;
464 ret = 0;
465 }
466 break;
467 case 's': /* stack */
468 if (arg[1] == 'a') {
469 ff->func = fetch_stack_address;
470 ff->data = NULL;
471 } else {
472 ret = strict_strtoul(arg + 1, 10, &param);
473 if (ret || param > PARAM_MAX_STACK)
474 ret = -EINVAL;
475 else {
476 ff->func = fetch_stack;
477 ff->data = (void *)param;
478 }
479 }
480 break;
481 case '@': /* memory or symbol */
482 if (isdigit(arg[1])) {
483 ret = strict_strtoul(arg + 1, 0, &param);
484 if (ret)
485 break;
486 ff->func = fetch_memory;
487 ff->data = (void *)param;
488 } else {
489 ret = split_symbol_offset(arg + 1, &offset);
490 if (ret)
491 break;
492 ff->data = alloc_symbol_cache(arg + 1,
493 offset);
494 if (ff->data)
495 ff->func = fetch_symbol;
496 else
497 ret = -EINVAL;
498 }
499 break;
500 case '+': /* indirect memory */
501 case '-':
502 tmp = strchr(arg, '(');
503 if (!tmp) {
504 ret = -EINVAL;
505 break;
506 }
507 *tmp = '\0';
508 ret = strict_strtol(arg + 1, 0, &offset);
509 if (ret)
510 break;
511 if (arg[0] == '-')
512 offset = -offset;
513 arg = tmp + 1;
514 tmp = strrchr(arg, ')');
515 if (tmp) {
516 struct indirect_fetch_data *id;
517 *tmp = '\0';
518 id = kzalloc(sizeof(struct indirect_fetch_data),
519 GFP_KERNEL);
520 if (!id)
521 return -ENOMEM;
522 id->offset = offset;
523 ret = parse_probe_arg(arg, &id->orig, is_return);
524 if (ret)
525 kfree(id);
526 else {
527 ff->func = fetch_indirect;
528 ff->data = (void *)id;
529 }
530 } else
531 ret = -EINVAL;
532 break;
533 default:
534 /* TODO: support custom handler */
535 ret = -EINVAL;
536 }
537 return ret;
538 }
539
540 static int create_trace_probe(int argc, char **argv)
541 {
542 /*
543 * Argument syntax:
544 * - Add kprobe: p[:[GRP/]EVENT] KSYM[+OFFS]|KADDR [FETCHARGS]
545 * - Add kretprobe: r[:[GRP/]EVENT] KSYM[+0] [FETCHARGS]
546 * Fetch args:
547 * aN : fetch Nth of function argument. (N:0-)
548 * rv : fetch return value
549 * ra : fetch return address
550 * sa : fetch stack address
551 * sN : fetch Nth of stack (N:0-)
552 * @ADDR : fetch memory at ADDR (ADDR should be in kernel)
553 * @SYM[+|-offs] : fetch memory at SYM +|- offs (SYM is a data symbol)
554 * %REG : fetch register REG
555 * Indirect memory fetch:
556 * +|-offs(ARG) : fetch memory at ARG +|- offs address.
557 * Alias name of args:
558 * NAME=FETCHARG : set NAME as alias of FETCHARG.
559 */
560 struct trace_probe *tp;
561 int i, ret = 0;
562 int is_return = 0;
563 char *symbol = NULL, *event = NULL, *arg = NULL, *group = NULL;
564 unsigned long offset = 0;
565 void *addr = NULL;
566 char buf[MAX_EVENT_NAME_LEN];
567
568 if (argc < 2)
569 return -EINVAL;
570
571 if (argv[0][0] == 'p')
572 is_return = 0;
573 else if (argv[0][0] == 'r')
574 is_return = 1;
575 else
576 return -EINVAL;
577
578 if (argv[0][1] == ':') {
579 event = &argv[0][2];
580 if (strchr(event, '/')) {
581 group = event;
582 event = strchr(group, '/') + 1;
583 event[-1] = '\0';
584 if (strlen(group) == 0) {
585 pr_info("Group name is not specifiled\n");
586 return -EINVAL;
587 }
588 }
589 if (strlen(event) == 0) {
590 pr_info("Event name is not specifiled\n");
591 return -EINVAL;
592 }
593 }
594
595 if (isdigit(argv[1][0])) {
596 if (is_return)
597 return -EINVAL;
598 /* an address specified */
599 ret = strict_strtoul(&argv[0][2], 0, (unsigned long *)&addr);
600 if (ret)
601 return ret;
602 } else {
603 /* a symbol specified */
604 symbol = argv[1];
605 /* TODO: support .init module functions */
606 ret = split_symbol_offset(symbol, &offset);
607 if (ret)
608 return ret;
609 if (offset && is_return)
610 return -EINVAL;
611 }
612 argc -= 2; argv += 2;
613
614 /* setup a probe */
615 if (!group)
616 group = KPROBE_EVENT_SYSTEM;
617 if (!event) {
618 /* Make a new event name */
619 if (symbol)
620 snprintf(buf, MAX_EVENT_NAME_LEN, "%c@%s%+ld",
621 is_return ? 'r' : 'p', symbol, offset);
622 else
623 snprintf(buf, MAX_EVENT_NAME_LEN, "%c@0x%p",
624 is_return ? 'r' : 'p', addr);
625 event = buf;
626 }
627 tp = alloc_trace_probe(group, event, addr, symbol, offset, argc,
628 is_return);
629 if (IS_ERR(tp))
630 return PTR_ERR(tp);
631
632 /* parse arguments */
633 ret = 0;
634 for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
635 /* Parse argument name */
636 arg = strchr(argv[i], '=');
637 if (arg)
638 *arg++ = '\0';
639 else
640 arg = argv[i];
641 tp->args[i].name = kstrdup(argv[i], GFP_KERNEL);
642
643 /* Parse fetch argument */
644 if (strlen(arg) > MAX_ARGSTR_LEN) {
645 pr_info("Argument%d(%s) is too long.\n", i, arg);
646 ret = -ENOSPC;
647 goto error;
648 }
649 ret = parse_probe_arg(arg, &tp->args[i].fetch, is_return);
650 if (ret)
651 goto error;
652 }
653 tp->nr_args = i;
654
655 ret = register_trace_probe(tp);
656 if (ret)
657 goto error;
658 return 0;
659
660 error:
661 free_trace_probe(tp);
662 return ret;
663 }
664
665 static void cleanup_all_probes(void)
666 {
667 struct trace_probe *tp;
668
669 mutex_lock(&probe_lock);
670 /* TODO: Use batch unregistration */
671 while (!list_empty(&probe_list)) {
672 tp = list_entry(probe_list.next, struct trace_probe, list);
673 unregister_trace_probe(tp);
674 free_trace_probe(tp);
675 }
676 mutex_unlock(&probe_lock);
677 }
678
679
680 /* Probes listing interfaces */
681 static void *probes_seq_start(struct seq_file *m, loff_t *pos)
682 {
683 mutex_lock(&probe_lock);
684 return seq_list_start(&probe_list, *pos);
685 }
686
687 static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
688 {
689 return seq_list_next(v, &probe_list, pos);
690 }
691
692 static void probes_seq_stop(struct seq_file *m, void *v)
693 {
694 mutex_unlock(&probe_lock);
695 }
696
697 static int probes_seq_show(struct seq_file *m, void *v)
698 {
699 struct trace_probe *tp = v;
700 int i, ret;
701 char buf[MAX_ARGSTR_LEN + 1];
702
703 seq_printf(m, "%c", probe_is_return(tp) ? 'r' : 'p');
704 seq_printf(m, ":%s", tp->call.name);
705
706 if (tp->symbol)
707 seq_printf(m, " %s+%u", probe_symbol(tp), tp->rp.kp.offset);
708 else
709 seq_printf(m, " 0x%p", tp->rp.kp.addr);
710
711 for (i = 0; i < tp->nr_args; i++) {
712 ret = probe_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i].fetch);
713 if (ret < 0) {
714 pr_warning("Argument%d decoding error(%d).\n", i, ret);
715 return ret;
716 }
717 seq_printf(m, " %s=%s", tp->args[i].name, buf);
718 }
719 seq_printf(m, "\n");
720 return 0;
721 }
722
723 static const struct seq_operations probes_seq_op = {
724 .start = probes_seq_start,
725 .next = probes_seq_next,
726 .stop = probes_seq_stop,
727 .show = probes_seq_show
728 };
729
730 static int probes_open(struct inode *inode, struct file *file)
731 {
732 if ((file->f_mode & FMODE_WRITE) &&
733 (file->f_flags & O_TRUNC))
734 cleanup_all_probes();
735
736 return seq_open(file, &probes_seq_op);
737 }
738
739 static int command_trace_probe(const char *buf)
740 {
741 char **argv;
742 int argc = 0, ret = 0;
743
744 argv = argv_split(GFP_KERNEL, buf, &argc);
745 if (!argv)
746 return -ENOMEM;
747
748 if (argc)
749 ret = create_trace_probe(argc, argv);
750
751 argv_free(argv);
752 return ret;
753 }
754
755 #define WRITE_BUFSIZE 128
756
757 static ssize_t probes_write(struct file *file, const char __user *buffer,
758 size_t count, loff_t *ppos)
759 {
760 char *kbuf, *tmp;
761 int ret;
762 size_t done;
763 size_t size;
764
765 kbuf = kmalloc(WRITE_BUFSIZE, GFP_KERNEL);
766 if (!kbuf)
767 return -ENOMEM;
768
769 ret = done = 0;
770 while (done < count) {
771 size = count - done;
772 if (size >= WRITE_BUFSIZE)
773 size = WRITE_BUFSIZE - 1;
774 if (copy_from_user(kbuf, buffer + done, size)) {
775 ret = -EFAULT;
776 goto out;
777 }
778 kbuf[size] = '\0';
779 tmp = strchr(kbuf, '\n');
780 if (tmp) {
781 *tmp = '\0';
782 size = tmp - kbuf + 1;
783 } else if (done + size < count) {
784 pr_warning("Line length is too long: "
785 "Should be less than %d.", WRITE_BUFSIZE);
786 ret = -EINVAL;
787 goto out;
788 }
789 done += size;
790 /* Remove comments */
791 tmp = strchr(kbuf, '#');
792 if (tmp)
793 *tmp = '\0';
794
795 ret = command_trace_probe(kbuf);
796 if (ret)
797 goto out;
798 }
799 ret = done;
800 out:
801 kfree(kbuf);
802 return ret;
803 }
804
805 static const struct file_operations kprobe_events_ops = {
806 .owner = THIS_MODULE,
807 .open = probes_open,
808 .read = seq_read,
809 .llseek = seq_lseek,
810 .release = seq_release,
811 .write = probes_write,
812 };
813
814 /* Probes profiling interfaces */
815 static int probes_profile_seq_show(struct seq_file *m, void *v)
816 {
817 struct trace_probe *tp = v;
818
819 seq_printf(m, " %-44s %15lu %15lu\n", tp->call.name, tp->nhit,
820 tp->rp.kp.nmissed);
821
822 return 0;
823 }
824
825 static const struct seq_operations profile_seq_op = {
826 .start = probes_seq_start,
827 .next = probes_seq_next,
828 .stop = probes_seq_stop,
829 .show = probes_profile_seq_show
830 };
831
832 static int profile_open(struct inode *inode, struct file *file)
833 {
834 return seq_open(file, &profile_seq_op);
835 }
836
837 static const struct file_operations kprobe_profile_ops = {
838 .owner = THIS_MODULE,
839 .open = profile_open,
840 .read = seq_read,
841 .llseek = seq_lseek,
842 .release = seq_release,
843 };
844
845 /* Kprobe handler */
846 static __kprobes int kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)
847 {
848 struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);
849 struct kprobe_trace_entry *entry;
850 struct ring_buffer_event *event;
851 struct ring_buffer *buffer;
852 int size, i, pc;
853 unsigned long irq_flags;
854 struct ftrace_event_call *call = &tp->call;
855
856 tp->nhit++;
857
858 local_save_flags(irq_flags);
859 pc = preempt_count();
860
861 size = SIZEOF_KPROBE_TRACE_ENTRY(tp->nr_args);
862
863 event = trace_current_buffer_lock_reserve(&buffer, call->id, size,
864 irq_flags, pc);
865 if (!event)
866 return 0;
867
868 entry = ring_buffer_event_data(event);
869 entry->nargs = tp->nr_args;
870 entry->ip = (unsigned long)kp->addr;
871 for (i = 0; i < tp->nr_args; i++)
872 entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
873
874 if (!filter_current_check_discard(buffer, call, entry, event))
875 trace_nowake_buffer_unlock_commit(buffer, event, irq_flags, pc);
876 return 0;
877 }
878
879 /* Kretprobe handler */
880 static __kprobes int kretprobe_trace_func(struct kretprobe_instance *ri,
881 struct pt_regs *regs)
882 {
883 struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
884 struct kretprobe_trace_entry *entry;
885 struct ring_buffer_event *event;
886 struct ring_buffer *buffer;
887 int size, i, pc;
888 unsigned long irq_flags;
889 struct ftrace_event_call *call = &tp->call;
890
891 local_save_flags(irq_flags);
892 pc = preempt_count();
893
894 size = SIZEOF_KRETPROBE_TRACE_ENTRY(tp->nr_args);
895
896 event = trace_current_buffer_lock_reserve(&buffer, call->id, size,
897 irq_flags, pc);
898 if (!event)
899 return 0;
900
901 entry = ring_buffer_event_data(event);
902 entry->nargs = tp->nr_args;
903 entry->func = (unsigned long)tp->rp.kp.addr;
904 entry->ret_ip = (unsigned long)ri->ret_addr;
905 for (i = 0; i < tp->nr_args; i++)
906 entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
907
908 if (!filter_current_check_discard(buffer, call, entry, event))
909 trace_nowake_buffer_unlock_commit(buffer, event, irq_flags, pc);
910
911 return 0;
912 }
913
914 /* Event entry printers */
915 enum print_line_t
916 print_kprobe_event(struct trace_iterator *iter, int flags)
917 {
918 struct kprobe_trace_entry *field;
919 struct trace_seq *s = &iter->seq;
920 struct trace_event *event;
921 struct trace_probe *tp;
922 int i;
923
924 field = (struct kprobe_trace_entry *)iter->ent;
925 event = ftrace_find_event(field->ent.type);
926 tp = container_of(event, struct trace_probe, event);
927
928 if (!trace_seq_printf(s, "%s: (", tp->call.name))
929 goto partial;
930
931 if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
932 goto partial;
933
934 if (!trace_seq_puts(s, ")"))
935 goto partial;
936
937 for (i = 0; i < field->nargs; i++)
938 if (!trace_seq_printf(s, " %s=%lx",
939 tp->args[i].name, field->args[i]))
940 goto partial;
941
942 if (!trace_seq_puts(s, "\n"))
943 goto partial;
944
945 return TRACE_TYPE_HANDLED;
946 partial:
947 return TRACE_TYPE_PARTIAL_LINE;
948 }
949
950 enum print_line_t
951 print_kretprobe_event(struct trace_iterator *iter, int flags)
952 {
953 struct kretprobe_trace_entry *field;
954 struct trace_seq *s = &iter->seq;
955 struct trace_event *event;
956 struct trace_probe *tp;
957 int i;
958
959 field = (struct kretprobe_trace_entry *)iter->ent;
960 event = ftrace_find_event(field->ent.type);
961 tp = container_of(event, struct trace_probe, event);
962
963 if (!trace_seq_printf(s, "%s: (", tp->call.name))
964 goto partial;
965
966 if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
967 goto partial;
968
969 if (!trace_seq_puts(s, " <- "))
970 goto partial;
971
972 if (!seq_print_ip_sym(s, field->func, flags & ~TRACE_ITER_SYM_OFFSET))
973 goto partial;
974
975 if (!trace_seq_puts(s, ")"))
976 goto partial;
977
978 for (i = 0; i < field->nargs; i++)
979 if (!trace_seq_printf(s, " %s=%lx",
980 tp->args[i].name, field->args[i]))
981 goto partial;
982
983 if (!trace_seq_puts(s, "\n"))
984 goto partial;
985
986 return TRACE_TYPE_HANDLED;
987 partial:
988 return TRACE_TYPE_PARTIAL_LINE;
989 }
990
991 static int probe_event_enable(struct ftrace_event_call *call)
992 {
993 struct trace_probe *tp = (struct trace_probe *)call->data;
994
995 tp->flags |= TP_FLAG_TRACE;
996 if (probe_is_return(tp))
997 return enable_kretprobe(&tp->rp);
998 else
999 return enable_kprobe(&tp->rp.kp);
1000 }
1001
1002 static void probe_event_disable(struct ftrace_event_call *call)
1003 {
1004 struct trace_probe *tp = (struct trace_probe *)call->data;
1005
1006 tp->flags &= ~TP_FLAG_TRACE;
1007 if (!(tp->flags & (TP_FLAG_TRACE | TP_FLAG_PROFILE))) {
1008 if (probe_is_return(tp))
1009 disable_kretprobe(&tp->rp);
1010 else
1011 disable_kprobe(&tp->rp.kp);
1012 }
1013 }
1014
1015 static int probe_event_raw_init(struct ftrace_event_call *event_call)
1016 {
1017 INIT_LIST_HEAD(&event_call->fields);
1018
1019 return 0;
1020 }
1021
1022 #undef DEFINE_FIELD
1023 #define DEFINE_FIELD(type, item, name, is_signed) \
1024 do { \
1025 ret = trace_define_field(event_call, #type, name, \
1026 offsetof(typeof(field), item), \
1027 sizeof(field.item), is_signed, \
1028 FILTER_OTHER); \
1029 if (ret) \
1030 return ret; \
1031 } while (0)
1032
1033 static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
1034 {
1035 int ret, i;
1036 struct kprobe_trace_entry field;
1037 struct trace_probe *tp = (struct trace_probe *)event_call->data;
1038
1039 ret = trace_define_common_fields(event_call);
1040 if (!ret)
1041 return ret;
1042
1043 DEFINE_FIELD(unsigned long, ip, "ip", 0);
1044 DEFINE_FIELD(int, nargs, "nargs", 1);
1045 /* Set argument names as fields */
1046 for (i = 0; i < tp->nr_args; i++)
1047 DEFINE_FIELD(unsigned long, args[i], tp->args[i].name, 0);
1048 return 0;
1049 }
1050
1051 static int kretprobe_event_define_fields(struct ftrace_event_call *event_call)
1052 {
1053 int ret, i;
1054 struct kretprobe_trace_entry field;
1055 struct trace_probe *tp = (struct trace_probe *)event_call->data;
1056
1057 ret = trace_define_common_fields(event_call);
1058 if (!ret)
1059 return ret;
1060
1061 DEFINE_FIELD(unsigned long, func, "func", 0);
1062 DEFINE_FIELD(unsigned long, ret_ip, "ret_ip", 0);
1063 DEFINE_FIELD(int, nargs, "nargs", 1);
1064 /* Set argument names as fields */
1065 for (i = 0; i < tp->nr_args; i++)
1066 DEFINE_FIELD(unsigned long, args[i], tp->args[i].name, 0);
1067 return 0;
1068 }
1069
1070 static int __probe_event_show_format(struct trace_seq *s,
1071 struct trace_probe *tp, const char *fmt,
1072 const char *arg)
1073 {
1074 int i;
1075
1076 /* Show format */
1077 if (!trace_seq_printf(s, "\nprint fmt: \"%s", fmt))
1078 return 0;
1079
1080 for (i = 0; i < tp->nr_args; i++)
1081 if (!trace_seq_printf(s, " %s=%%lx", tp->args[i].name))
1082 return 0;
1083
1084 if (!trace_seq_printf(s, "\", %s", arg))
1085 return 0;
1086
1087 for (i = 0; i < tp->nr_args; i++)
1088 if (!trace_seq_printf(s, ", REC->%s", tp->args[i].name))
1089 return 0;
1090
1091 return trace_seq_puts(s, "\n");
1092 }
1093
1094 #undef SHOW_FIELD
1095 #define SHOW_FIELD(type, item, name) \
1096 do { \
1097 ret = trace_seq_printf(s, "\tfield: " #type " %s;\t" \
1098 "offset:%u;\tsize:%u;\n", name, \
1099 (unsigned int)offsetof(typeof(field), item),\
1100 (unsigned int)sizeof(type)); \
1101 if (!ret) \
1102 return 0; \
1103 } while (0)
1104
1105 static int kprobe_event_show_format(struct ftrace_event_call *call,
1106 struct trace_seq *s)
1107 {
1108 struct kprobe_trace_entry field __attribute__((unused));
1109 int ret, i;
1110 struct trace_probe *tp = (struct trace_probe *)call->data;
1111
1112 SHOW_FIELD(unsigned long, ip, "ip");
1113 SHOW_FIELD(int, nargs, "nargs");
1114
1115 /* Show fields */
1116 for (i = 0; i < tp->nr_args; i++)
1117 SHOW_FIELD(unsigned long, args[i], tp->args[i].name);
1118 trace_seq_puts(s, "\n");
1119
1120 return __probe_event_show_format(s, tp, "(%lx)", "REC->ip");
1121 }
1122
1123 static int kretprobe_event_show_format(struct ftrace_event_call *call,
1124 struct trace_seq *s)
1125 {
1126 struct kretprobe_trace_entry field __attribute__((unused));
1127 int ret, i;
1128 struct trace_probe *tp = (struct trace_probe *)call->data;
1129
1130 SHOW_FIELD(unsigned long, func, "func");
1131 SHOW_FIELD(unsigned long, ret_ip, "ret_ip");
1132 SHOW_FIELD(int, nargs, "nargs");
1133
1134 /* Show fields */
1135 for (i = 0; i < tp->nr_args; i++)
1136 SHOW_FIELD(unsigned long, args[i], tp->args[i].name);
1137 trace_seq_puts(s, "\n");
1138
1139 return __probe_event_show_format(s, tp, "(%lx <- %lx)",
1140 "REC->func, REC->ret_ip");
1141 }
1142
1143 #ifdef CONFIG_EVENT_PROFILE
1144
1145 /* Kprobe profile handler */
1146 static __kprobes int kprobe_profile_func(struct kprobe *kp,
1147 struct pt_regs *regs)
1148 {
1149 struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);
1150 struct ftrace_event_call *call = &tp->call;
1151 struct kprobe_trace_entry *entry;
1152 struct trace_entry *ent;
1153 int size, __size, i, pc, __cpu;
1154 unsigned long irq_flags;
1155 char *raw_data;
1156
1157 pc = preempt_count();
1158 __size = SIZEOF_KPROBE_TRACE_ENTRY(tp->nr_args);
1159 size = ALIGN(__size + sizeof(u32), sizeof(u64));
1160 size -= sizeof(u32);
1161 if (WARN_ONCE(size > FTRACE_MAX_PROFILE_SIZE,
1162 "profile buffer not large enough"))
1163 return 0;
1164
1165 /*
1166 * Protect the non nmi buffer
1167 * This also protects the rcu read side
1168 */
1169 local_irq_save(irq_flags);
1170 __cpu = smp_processor_id();
1171
1172 if (in_nmi())
1173 raw_data = rcu_dereference(trace_profile_buf_nmi);
1174 else
1175 raw_data = rcu_dereference(trace_profile_buf);
1176
1177 if (!raw_data)
1178 goto end;
1179
1180 raw_data = per_cpu_ptr(raw_data, __cpu);
1181 /* Zero dead bytes from alignment to avoid buffer leak to userspace */
1182 *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
1183 entry = (struct kprobe_trace_entry *)raw_data;
1184 ent = &entry->ent;
1185
1186 tracing_generic_entry_update(ent, irq_flags, pc);
1187 ent->type = call->id;
1188 entry->nargs = tp->nr_args;
1189 entry->ip = (unsigned long)kp->addr;
1190 for (i = 0; i < tp->nr_args; i++)
1191 entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
1192 perf_tp_event(call->id, entry->ip, 1, entry, size);
1193 end:
1194 local_irq_restore(irq_flags);
1195 return 0;
1196 }
1197
1198 /* Kretprobe profile handler */
1199 static __kprobes int kretprobe_profile_func(struct kretprobe_instance *ri,
1200 struct pt_regs *regs)
1201 {
1202 struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
1203 struct ftrace_event_call *call = &tp->call;
1204 struct kretprobe_trace_entry *entry;
1205 struct trace_entry *ent;
1206 int size, __size, i, pc, __cpu;
1207 unsigned long irq_flags;
1208 char *raw_data;
1209
1210 pc = preempt_count();
1211 __size = SIZEOF_KRETPROBE_TRACE_ENTRY(tp->nr_args);
1212 size = ALIGN(__size + sizeof(u32), sizeof(u64));
1213 size -= sizeof(u32);
1214 if (WARN_ONCE(size > FTRACE_MAX_PROFILE_SIZE,
1215 "profile buffer not large enough"))
1216 return 0;
1217
1218 /*
1219 * Protect the non nmi buffer
1220 * This also protects the rcu read side
1221 */
1222 local_irq_save(irq_flags);
1223 __cpu = smp_processor_id();
1224
1225 if (in_nmi())
1226 raw_data = rcu_dereference(trace_profile_buf_nmi);
1227 else
1228 raw_data = rcu_dereference(trace_profile_buf);
1229
1230 if (!raw_data)
1231 goto end;
1232
1233 raw_data = per_cpu_ptr(raw_data, __cpu);
1234 /* Zero dead bytes from alignment to avoid buffer leak to userspace */
1235 *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
1236 entry = (struct kretprobe_trace_entry *)raw_data;
1237 ent = &entry->ent;
1238
1239 tracing_generic_entry_update(ent, irq_flags, pc);
1240 ent->type = call->id;
1241 entry->nargs = tp->nr_args;
1242 entry->func = (unsigned long)tp->rp.kp.addr;
1243 entry->ret_ip = (unsigned long)ri->ret_addr;
1244 for (i = 0; i < tp->nr_args; i++)
1245 entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
1246 perf_tp_event(call->id, entry->ret_ip, 1, entry, size);
1247 end:
1248 local_irq_restore(irq_flags);
1249 return 0;
1250 }
1251
1252 static int probe_profile_enable(struct ftrace_event_call *call)
1253 {
1254 struct trace_probe *tp = (struct trace_probe *)call->data;
1255
1256 tp->flags |= TP_FLAG_PROFILE;
1257
1258 if (probe_is_return(tp))
1259 return enable_kretprobe(&tp->rp);
1260 else
1261 return enable_kprobe(&tp->rp.kp);
1262 }
1263
1264 static void probe_profile_disable(struct ftrace_event_call *call)
1265 {
1266 struct trace_probe *tp = (struct trace_probe *)call->data;
1267
1268 tp->flags &= ~TP_FLAG_PROFILE;
1269
1270 if (!(tp->flags & TP_FLAG_TRACE)) {
1271 if (probe_is_return(tp))
1272 disable_kretprobe(&tp->rp);
1273 else
1274 disable_kprobe(&tp->rp.kp);
1275 }
1276 }
1277 #endif /* CONFIG_EVENT_PROFILE */
1278
1279
1280 static __kprobes
1281 int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs)
1282 {
1283 struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);
1284
1285 if (tp->flags & TP_FLAG_TRACE)
1286 kprobe_trace_func(kp, regs);
1287 #ifdef CONFIG_EVENT_PROFILE
1288 if (tp->flags & TP_FLAG_PROFILE)
1289 kprobe_profile_func(kp, regs);
1290 #endif /* CONFIG_EVENT_PROFILE */
1291 return 0; /* We don't tweek kernel, so just return 0 */
1292 }
1293
1294 static __kprobes
1295 int kretprobe_dispatcher(struct kretprobe_instance *ri, struct pt_regs *regs)
1296 {
1297 struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
1298
1299 if (tp->flags & TP_FLAG_TRACE)
1300 kretprobe_trace_func(ri, regs);
1301 #ifdef CONFIG_EVENT_PROFILE
1302 if (tp->flags & TP_FLAG_PROFILE)
1303 kretprobe_profile_func(ri, regs);
1304 #endif /* CONFIG_EVENT_PROFILE */
1305 return 0; /* We don't tweek kernel, so just return 0 */
1306 }
1307
1308 static int register_probe_event(struct trace_probe *tp)
1309 {
1310 struct ftrace_event_call *call = &tp->call;
1311 int ret;
1312
1313 /* Initialize ftrace_event_call */
1314 if (probe_is_return(tp)) {
1315 tp->event.trace = print_kretprobe_event;
1316 call->raw_init = probe_event_raw_init;
1317 call->show_format = kretprobe_event_show_format;
1318 call->define_fields = kretprobe_event_define_fields;
1319 } else {
1320 tp->event.trace = print_kprobe_event;
1321 call->raw_init = probe_event_raw_init;
1322 call->show_format = kprobe_event_show_format;
1323 call->define_fields = kprobe_event_define_fields;
1324 }
1325 call->event = &tp->event;
1326 call->id = register_ftrace_event(&tp->event);
1327 if (!call->id)
1328 return -ENODEV;
1329 call->enabled = 0;
1330 call->regfunc = probe_event_enable;
1331 call->unregfunc = probe_event_disable;
1332
1333 #ifdef CONFIG_EVENT_PROFILE
1334 atomic_set(&call->profile_count, -1);
1335 call->profile_enable = probe_profile_enable;
1336 call->profile_disable = probe_profile_disable;
1337 #endif
1338 call->data = tp;
1339 ret = trace_add_event_call(call);
1340 if (ret) {
1341 pr_info("Failed to register kprobe event: %s\n", call->name);
1342 unregister_ftrace_event(&tp->event);
1343 }
1344 return ret;
1345 }
1346
1347 static void unregister_probe_event(struct trace_probe *tp)
1348 {
1349 /* tp->event is unregistered in trace_remove_event_call() */
1350 trace_remove_event_call(&tp->call);
1351 }
1352
1353 /* Make a debugfs interface for controling probe points */
1354 static __init int init_kprobe_trace(void)
1355 {
1356 struct dentry *d_tracer;
1357 struct dentry *entry;
1358
1359 d_tracer = tracing_init_dentry();
1360 if (!d_tracer)
1361 return 0;
1362
1363 entry = debugfs_create_file("kprobe_events", 0644, d_tracer,
1364 NULL, &kprobe_events_ops);
1365
1366 /* Event list interface */
1367 if (!entry)
1368 pr_warning("Could not create debugfs "
1369 "'kprobe_events' entry\n");
1370
1371 /* Profile interface */
1372 entry = debugfs_create_file("kprobe_profile", 0444, d_tracer,
1373 NULL, &kprobe_profile_ops);
1374
1375 if (!entry)
1376 pr_warning("Could not create debugfs "
1377 "'kprobe_profile' entry\n");
1378 return 0;
1379 }
1380 fs_initcall(init_kprobe_trace);
1381
1382
1383 #ifdef CONFIG_FTRACE_STARTUP_TEST
1384
1385 static int kprobe_trace_selftest_target(int a1, int a2, int a3,
1386 int a4, int a5, int a6)
1387 {
1388 return a1 + a2 + a3 + a4 + a5 + a6;
1389 }
1390
1391 static __init int kprobe_trace_self_tests_init(void)
1392 {
1393 int ret;
1394 int (*target)(int, int, int, int, int, int);
1395
1396 target = kprobe_trace_selftest_target;
1397
1398 pr_info("Testing kprobe tracing: ");
1399
1400 ret = command_trace_probe("p:testprobe kprobe_trace_selftest_target "
1401 "a1 a2 a3 a4 a5 a6");
1402 if (WARN_ON_ONCE(ret))
1403 pr_warning("error enabling function entry\n");
1404
1405 ret = command_trace_probe("r:testprobe2 kprobe_trace_selftest_target "
1406 "ra rv");
1407 if (WARN_ON_ONCE(ret))
1408 pr_warning("error enabling function return\n");
1409
1410 ret = target(1, 2, 3, 4, 5, 6);
1411
1412 cleanup_all_probes();
1413
1414 pr_cont("OK\n");
1415 return 0;
1416 }
1417
1418 late_initcall(kprobe_trace_self_tests_init);
1419
1420 #endif
Linux kernel - Deliverables
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