uprobes/perf: Avoid perf_trace_buf_prepare/submit if ->perf_events is empty
[linux-3.10.git] / kernel / trace / trace_kprobe.c
1 /*
2  * Kprobes-based tracing events
3  *
4  * Created by Masami Hiramatsu <mhiramat@redhat.com>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  * GNU General Public License for more details.
14  *
15  * You should have received a copy of the GNU General Public License
16  * along with this program; if not, write to the Free Software
17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18  */
19
20 #include <linux/module.h>
21 #include <linux/uaccess.h>
22
23 #include "trace_probe.h"
24
25 #define KPROBE_EVENT_SYSTEM "kprobes"
26
27 /**
28  * Kprobe event core functions
29  */
30
31 struct trace_probe {
32         struct list_head        list;
33         struct kretprobe        rp;     /* Use rp.kp for kprobe use */
34         unsigned long           nhit;
35         unsigned int            flags;  /* For TP_FLAG_* */
36         const char              *symbol;        /* symbol name */
37         struct ftrace_event_class       class;
38         struct ftrace_event_call        call;
39         ssize_t                 size;           /* trace entry size */
40         unsigned int            nr_args;
41         struct probe_arg        args[];
42 };
43
44 #define SIZEOF_TRACE_PROBE(n)                   \
45         (offsetof(struct trace_probe, args) +   \
46         (sizeof(struct probe_arg) * (n)))
47
48
49 static __kprobes int trace_probe_is_return(struct trace_probe *tp)
50 {
51         return tp->rp.handler != NULL;
52 }
53
54 static __kprobes const char *trace_probe_symbol(struct trace_probe *tp)
55 {
56         return tp->symbol ? tp->symbol : "unknown";
57 }
58
59 static __kprobes unsigned long trace_probe_offset(struct trace_probe *tp)
60 {
61         return tp->rp.kp.offset;
62 }
63
64 static __kprobes bool trace_probe_is_enabled(struct trace_probe *tp)
65 {
66         return !!(tp->flags & (TP_FLAG_TRACE | TP_FLAG_PROFILE));
67 }
68
69 static __kprobes bool trace_probe_is_registered(struct trace_probe *tp)
70 {
71         return !!(tp->flags & TP_FLAG_REGISTERED);
72 }
73
74 static __kprobes bool trace_probe_has_gone(struct trace_probe *tp)
75 {
76         return !!(kprobe_gone(&tp->rp.kp));
77 }
78
79 static __kprobes bool trace_probe_within_module(struct trace_probe *tp,
80                                                 struct module *mod)
81 {
82         int len = strlen(mod->name);
83         const char *name = trace_probe_symbol(tp);
84         return strncmp(mod->name, name, len) == 0 && name[len] == ':';
85 }
86
87 static __kprobes bool trace_probe_is_on_module(struct trace_probe *tp)
88 {
89         return !!strchr(trace_probe_symbol(tp), ':');
90 }
91
92 static int register_probe_event(struct trace_probe *tp);
93 static void unregister_probe_event(struct trace_probe *tp);
94
95 static DEFINE_MUTEX(probe_lock);
96 static LIST_HEAD(probe_list);
97
98 static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
99 static int kretprobe_dispatcher(struct kretprobe_instance *ri,
100                                 struct pt_regs *regs);
101
102 /*
103  * Allocate new trace_probe and initialize it (including kprobes).
104  */
105 static struct trace_probe *alloc_trace_probe(const char *group,
106                                              const char *event,
107                                              void *addr,
108                                              const char *symbol,
109                                              unsigned long offs,
110                                              int nargs, bool is_return)
111 {
112         struct trace_probe *tp;
113         int ret = -ENOMEM;
114
115         tp = kzalloc(SIZEOF_TRACE_PROBE(nargs), GFP_KERNEL);
116         if (!tp)
117                 return ERR_PTR(ret);
118
119         if (symbol) {
120                 tp->symbol = kstrdup(symbol, GFP_KERNEL);
121                 if (!tp->symbol)
122                         goto error;
123                 tp->rp.kp.symbol_name = tp->symbol;
124                 tp->rp.kp.offset = offs;
125         } else
126                 tp->rp.kp.addr = addr;
127
128         if (is_return)
129                 tp->rp.handler = kretprobe_dispatcher;
130         else
131                 tp->rp.kp.pre_handler = kprobe_dispatcher;
132
133         if (!event || !is_good_name(event)) {
134                 ret = -EINVAL;
135                 goto error;
136         }
137
138         tp->call.class = &tp->class;
139         tp->call.name = kstrdup(event, GFP_KERNEL);
140         if (!tp->call.name)
141                 goto error;
142
143         if (!group || !is_good_name(group)) {
144                 ret = -EINVAL;
145                 goto error;
146         }
147
148         tp->class.system = kstrdup(group, GFP_KERNEL);
149         if (!tp->class.system)
150                 goto error;
151
152         INIT_LIST_HEAD(&tp->list);
153         return tp;
154 error:
155         kfree(tp->call.name);
156         kfree(tp->symbol);
157         kfree(tp);
158         return ERR_PTR(ret);
159 }
160
161 static void free_trace_probe(struct trace_probe *tp)
162 {
163         int i;
164
165         for (i = 0; i < tp->nr_args; i++)
166                 traceprobe_free_probe_arg(&tp->args[i]);
167
168         kfree(tp->call.class->system);
169         kfree(tp->call.name);
170         kfree(tp->symbol);
171         kfree(tp);
172 }
173
174 static struct trace_probe *find_trace_probe(const char *event,
175                                             const char *group)
176 {
177         struct trace_probe *tp;
178
179         list_for_each_entry(tp, &probe_list, list)
180                 if (strcmp(tp->call.name, event) == 0 &&
181                     strcmp(tp->call.class->system, group) == 0)
182                         return tp;
183         return NULL;
184 }
185
186 /* Enable trace_probe - @flag must be TP_FLAG_TRACE or TP_FLAG_PROFILE */
187 static int enable_trace_probe(struct trace_probe *tp, int flag)
188 {
189         int ret = 0;
190
191         tp->flags |= flag;
192         if (trace_probe_is_enabled(tp) && trace_probe_is_registered(tp) &&
193             !trace_probe_has_gone(tp)) {
194                 if (trace_probe_is_return(tp))
195                         ret = enable_kretprobe(&tp->rp);
196                 else
197                         ret = enable_kprobe(&tp->rp.kp);
198         }
199
200         return ret;
201 }
202
203 /* Disable trace_probe - @flag must be TP_FLAG_TRACE or TP_FLAG_PROFILE */
204 static void disable_trace_probe(struct trace_probe *tp, int flag)
205 {
206         tp->flags &= ~flag;
207         if (!trace_probe_is_enabled(tp) && trace_probe_is_registered(tp)) {
208                 if (trace_probe_is_return(tp))
209                         disable_kretprobe(&tp->rp);
210                 else
211                         disable_kprobe(&tp->rp.kp);
212         }
213 }
214
215 /* Internal register function - just handle k*probes and flags */
216 static int __register_trace_probe(struct trace_probe *tp)
217 {
218         int i, ret;
219
220         if (trace_probe_is_registered(tp))
221                 return -EINVAL;
222
223         for (i = 0; i < tp->nr_args; i++)
224                 traceprobe_update_arg(&tp->args[i]);
225
226         /* Set/clear disabled flag according to tp->flag */
227         if (trace_probe_is_enabled(tp))
228                 tp->rp.kp.flags &= ~KPROBE_FLAG_DISABLED;
229         else
230                 tp->rp.kp.flags |= KPROBE_FLAG_DISABLED;
231
232         if (trace_probe_is_return(tp))
233                 ret = register_kretprobe(&tp->rp);
234         else
235                 ret = register_kprobe(&tp->rp.kp);
236
237         if (ret == 0)
238                 tp->flags |= TP_FLAG_REGISTERED;
239         else {
240                 pr_warning("Could not insert probe at %s+%lu: %d\n",
241                            trace_probe_symbol(tp), trace_probe_offset(tp), ret);
242                 if (ret == -ENOENT && trace_probe_is_on_module(tp)) {
243                         pr_warning("This probe might be able to register after"
244                                    "target module is loaded. Continue.\n");
245                         ret = 0;
246                 } else if (ret == -EILSEQ) {
247                         pr_warning("Probing address(0x%p) is not an "
248                                    "instruction boundary.\n",
249                                    tp->rp.kp.addr);
250                         ret = -EINVAL;
251                 }
252         }
253
254         return ret;
255 }
256
257 /* Internal unregister function - just handle k*probes and flags */
258 static void __unregister_trace_probe(struct trace_probe *tp)
259 {
260         if (trace_probe_is_registered(tp)) {
261                 if (trace_probe_is_return(tp))
262                         unregister_kretprobe(&tp->rp);
263                 else
264                         unregister_kprobe(&tp->rp.kp);
265                 tp->flags &= ~TP_FLAG_REGISTERED;
266                 /* Cleanup kprobe for reuse */
267                 if (tp->rp.kp.symbol_name)
268                         tp->rp.kp.addr = NULL;
269         }
270 }
271
272 /* Unregister a trace_probe and probe_event: call with locking probe_lock */
273 static int unregister_trace_probe(struct trace_probe *tp)
274 {
275         /* Enabled event can not be unregistered */
276         if (trace_probe_is_enabled(tp))
277                 return -EBUSY;
278
279         __unregister_trace_probe(tp);
280         list_del(&tp->list);
281         unregister_probe_event(tp);
282
283         return 0;
284 }
285
286 /* Register a trace_probe and probe_event */
287 static int register_trace_probe(struct trace_probe *tp)
288 {
289         struct trace_probe *old_tp;
290         int ret;
291
292         mutex_lock(&probe_lock);
293
294         /* Delete old (same name) event if exist */
295         old_tp = find_trace_probe(tp->call.name, tp->call.class->system);
296         if (old_tp) {
297                 ret = unregister_trace_probe(old_tp);
298                 if (ret < 0)
299                         goto end;
300                 free_trace_probe(old_tp);
301         }
302
303         /* Register new event */
304         ret = register_probe_event(tp);
305         if (ret) {
306                 pr_warning("Failed to register probe event(%d)\n", ret);
307                 goto end;
308         }
309
310         /* Register k*probe */
311         ret = __register_trace_probe(tp);
312         if (ret < 0)
313                 unregister_probe_event(tp);
314         else
315                 list_add_tail(&tp->list, &probe_list);
316
317 end:
318         mutex_unlock(&probe_lock);
319         return ret;
320 }
321
322 /* Module notifier call back, checking event on the module */
323 static int trace_probe_module_callback(struct notifier_block *nb,
324                                        unsigned long val, void *data)
325 {
326         struct module *mod = data;
327         struct trace_probe *tp;
328         int ret;
329
330         if (val != MODULE_STATE_COMING)
331                 return NOTIFY_DONE;
332
333         /* Update probes on coming module */
334         mutex_lock(&probe_lock);
335         list_for_each_entry(tp, &probe_list, list) {
336                 if (trace_probe_within_module(tp, mod)) {
337                         /* Don't need to check busy - this should have gone. */
338                         __unregister_trace_probe(tp);
339                         ret = __register_trace_probe(tp);
340                         if (ret)
341                                 pr_warning("Failed to re-register probe %s on"
342                                            "%s: %d\n",
343                                            tp->call.name, mod->name, ret);
344                 }
345         }
346         mutex_unlock(&probe_lock);
347
348         return NOTIFY_DONE;
349 }
350
351 static struct notifier_block trace_probe_module_nb = {
352         .notifier_call = trace_probe_module_callback,
353         .priority = 1   /* Invoked after kprobe module callback */
354 };
355
356 static int create_trace_probe(int argc, char **argv)
357 {
358         /*
359          * Argument syntax:
360          *  - Add kprobe: p[:[GRP/]EVENT] [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS]
361          *  - Add kretprobe: r[:[GRP/]EVENT] [MOD:]KSYM[+0] [FETCHARGS]
362          * Fetch args:
363          *  $retval     : fetch return value
364          *  $stack      : fetch stack address
365          *  $stackN     : fetch Nth of stack (N:0-)
366          *  @ADDR       : fetch memory at ADDR (ADDR should be in kernel)
367          *  @SYM[+|-offs] : fetch memory at SYM +|- offs (SYM is a data symbol)
368          *  %REG        : fetch register REG
369          * Dereferencing memory fetch:
370          *  +|-offs(ARG) : fetch memory at ARG +|- offs address.
371          * Alias name of args:
372          *  NAME=FETCHARG : set NAME as alias of FETCHARG.
373          * Type of args:
374          *  FETCHARG:TYPE : use TYPE instead of unsigned long.
375          */
376         struct trace_probe *tp;
377         int i, ret = 0;
378         bool is_return = false, is_delete = false;
379         char *symbol = NULL, *event = NULL, *group = NULL;
380         char *arg;
381         unsigned long offset = 0;
382         void *addr = NULL;
383         char buf[MAX_EVENT_NAME_LEN];
384
385         /* argc must be >= 1 */
386         if (argv[0][0] == 'p')
387                 is_return = false;
388         else if (argv[0][0] == 'r')
389                 is_return = true;
390         else if (argv[0][0] == '-')
391                 is_delete = true;
392         else {
393                 pr_info("Probe definition must be started with 'p', 'r' or"
394                         " '-'.\n");
395                 return -EINVAL;
396         }
397
398         if (argv[0][1] == ':') {
399                 event = &argv[0][2];
400                 if (strchr(event, '/')) {
401                         group = event;
402                         event = strchr(group, '/') + 1;
403                         event[-1] = '\0';
404                         if (strlen(group) == 0) {
405                                 pr_info("Group name is not specified\n");
406                                 return -EINVAL;
407                         }
408                 }
409                 if (strlen(event) == 0) {
410                         pr_info("Event name is not specified\n");
411                         return -EINVAL;
412                 }
413         }
414         if (!group)
415                 group = KPROBE_EVENT_SYSTEM;
416
417         if (is_delete) {
418                 if (!event) {
419                         pr_info("Delete command needs an event name.\n");
420                         return -EINVAL;
421                 }
422                 mutex_lock(&probe_lock);
423                 tp = find_trace_probe(event, group);
424                 if (!tp) {
425                         mutex_unlock(&probe_lock);
426                         pr_info("Event %s/%s doesn't exist.\n", group, event);
427                         return -ENOENT;
428                 }
429                 /* delete an event */
430                 ret = unregister_trace_probe(tp);
431                 if (ret == 0)
432                         free_trace_probe(tp);
433                 mutex_unlock(&probe_lock);
434                 return ret;
435         }
436
437         if (argc < 2) {
438                 pr_info("Probe point is not specified.\n");
439                 return -EINVAL;
440         }
441         if (isdigit(argv[1][0])) {
442                 if (is_return) {
443                         pr_info("Return probe point must be a symbol.\n");
444                         return -EINVAL;
445                 }
446                 /* an address specified */
447                 ret = kstrtoul(&argv[1][0], 0, (unsigned long *)&addr);
448                 if (ret) {
449                         pr_info("Failed to parse address.\n");
450                         return ret;
451                 }
452         } else {
453                 /* a symbol specified */
454                 symbol = argv[1];
455                 /* TODO: support .init module functions */
456                 ret = traceprobe_split_symbol_offset(symbol, &offset);
457                 if (ret) {
458                         pr_info("Failed to parse symbol.\n");
459                         return ret;
460                 }
461                 if (offset && is_return) {
462                         pr_info("Return probe must be used without offset.\n");
463                         return -EINVAL;
464                 }
465         }
466         argc -= 2; argv += 2;
467
468         /* setup a probe */
469         if (!event) {
470                 /* Make a new event name */
471                 if (symbol)
472                         snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_%ld",
473                                  is_return ? 'r' : 'p', symbol, offset);
474                 else
475                         snprintf(buf, MAX_EVENT_NAME_LEN, "%c_0x%p",
476                                  is_return ? 'r' : 'p', addr);
477                 event = buf;
478         }
479         tp = alloc_trace_probe(group, event, addr, symbol, offset, argc,
480                                is_return);
481         if (IS_ERR(tp)) {
482                 pr_info("Failed to allocate trace_probe.(%d)\n",
483                         (int)PTR_ERR(tp));
484                 return PTR_ERR(tp);
485         }
486
487         /* parse arguments */
488         ret = 0;
489         for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
490                 /* Increment count for freeing args in error case */
491                 tp->nr_args++;
492
493                 /* Parse argument name */
494                 arg = strchr(argv[i], '=');
495                 if (arg) {
496                         *arg++ = '\0';
497                         tp->args[i].name = kstrdup(argv[i], GFP_KERNEL);
498                 } else {
499                         arg = argv[i];
500                         /* If argument name is omitted, set "argN" */
501                         snprintf(buf, MAX_EVENT_NAME_LEN, "arg%d", i + 1);
502                         tp->args[i].name = kstrdup(buf, GFP_KERNEL);
503                 }
504
505                 if (!tp->args[i].name) {
506                         pr_info("Failed to allocate argument[%d] name.\n", i);
507                         ret = -ENOMEM;
508                         goto error;
509                 }
510
511                 if (!is_good_name(tp->args[i].name)) {
512                         pr_info("Invalid argument[%d] name: %s\n",
513                                 i, tp->args[i].name);
514                         ret = -EINVAL;
515                         goto error;
516                 }
517
518                 if (traceprobe_conflict_field_name(tp->args[i].name,
519                                                         tp->args, i)) {
520                         pr_info("Argument[%d] name '%s' conflicts with "
521                                 "another field.\n", i, argv[i]);
522                         ret = -EINVAL;
523                         goto error;
524                 }
525
526                 /* Parse fetch argument */
527                 ret = traceprobe_parse_probe_arg(arg, &tp->size, &tp->args[i],
528                                                 is_return, true);
529                 if (ret) {
530                         pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
531                         goto error;
532                 }
533         }
534
535         ret = register_trace_probe(tp);
536         if (ret)
537                 goto error;
538         return 0;
539
540 error:
541         free_trace_probe(tp);
542         return ret;
543 }
544
545 static int release_all_trace_probes(void)
546 {
547         struct trace_probe *tp;
548         int ret = 0;
549
550         mutex_lock(&probe_lock);
551         /* Ensure no probe is in use. */
552         list_for_each_entry(tp, &probe_list, list)
553                 if (trace_probe_is_enabled(tp)) {
554                         ret = -EBUSY;
555                         goto end;
556                 }
557         /* TODO: Use batch unregistration */
558         while (!list_empty(&probe_list)) {
559                 tp = list_entry(probe_list.next, struct trace_probe, list);
560                 unregister_trace_probe(tp);
561                 free_trace_probe(tp);
562         }
563
564 end:
565         mutex_unlock(&probe_lock);
566
567         return ret;
568 }
569
570 /* Probes listing interfaces */
571 static void *probes_seq_start(struct seq_file *m, loff_t *pos)
572 {
573         mutex_lock(&probe_lock);
574         return seq_list_start(&probe_list, *pos);
575 }
576
577 static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
578 {
579         return seq_list_next(v, &probe_list, pos);
580 }
581
582 static void probes_seq_stop(struct seq_file *m, void *v)
583 {
584         mutex_unlock(&probe_lock);
585 }
586
587 static int probes_seq_show(struct seq_file *m, void *v)
588 {
589         struct trace_probe *tp = v;
590         int i;
591
592         seq_printf(m, "%c", trace_probe_is_return(tp) ? 'r' : 'p');
593         seq_printf(m, ":%s/%s", tp->call.class->system, tp->call.name);
594
595         if (!tp->symbol)
596                 seq_printf(m, " 0x%p", tp->rp.kp.addr);
597         else if (tp->rp.kp.offset)
598                 seq_printf(m, " %s+%u", trace_probe_symbol(tp),
599                            tp->rp.kp.offset);
600         else
601                 seq_printf(m, " %s", trace_probe_symbol(tp));
602
603         for (i = 0; i < tp->nr_args; i++)
604                 seq_printf(m, " %s=%s", tp->args[i].name, tp->args[i].comm);
605         seq_printf(m, "\n");
606
607         return 0;
608 }
609
610 static const struct seq_operations probes_seq_op = {
611         .start  = probes_seq_start,
612         .next   = probes_seq_next,
613         .stop   = probes_seq_stop,
614         .show   = probes_seq_show
615 };
616
617 static int probes_open(struct inode *inode, struct file *file)
618 {
619         int ret;
620
621         if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
622                 ret = release_all_trace_probes();
623                 if (ret < 0)
624                         return ret;
625         }
626
627         return seq_open(file, &probes_seq_op);
628 }
629
630 static ssize_t probes_write(struct file *file, const char __user *buffer,
631                             size_t count, loff_t *ppos)
632 {
633         return traceprobe_probes_write(file, buffer, count, ppos,
634                         create_trace_probe);
635 }
636
637 static const struct file_operations kprobe_events_ops = {
638         .owner          = THIS_MODULE,
639         .open           = probes_open,
640         .read           = seq_read,
641         .llseek         = seq_lseek,
642         .release        = seq_release,
643         .write          = probes_write,
644 };
645
646 /* Probes profiling interfaces */
647 static int probes_profile_seq_show(struct seq_file *m, void *v)
648 {
649         struct trace_probe *tp = v;
650
651         seq_printf(m, "  %-44s %15lu %15lu\n", tp->call.name, tp->nhit,
652                    tp->rp.kp.nmissed);
653
654         return 0;
655 }
656
657 static const struct seq_operations profile_seq_op = {
658         .start  = probes_seq_start,
659         .next   = probes_seq_next,
660         .stop   = probes_seq_stop,
661         .show   = probes_profile_seq_show
662 };
663
664 static int profile_open(struct inode *inode, struct file *file)
665 {
666         return seq_open(file, &profile_seq_op);
667 }
668
669 static const struct file_operations kprobe_profile_ops = {
670         .owner          = THIS_MODULE,
671         .open           = profile_open,
672         .read           = seq_read,
673         .llseek         = seq_lseek,
674         .release        = seq_release,
675 };
676
677 /* Sum up total data length for dynamic arraies (strings) */
678 static __kprobes int __get_data_size(struct trace_probe *tp,
679                                      struct pt_regs *regs)
680 {
681         int i, ret = 0;
682         u32 len;
683
684         for (i = 0; i < tp->nr_args; i++)
685                 if (unlikely(tp->args[i].fetch_size.fn)) {
686                         call_fetch(&tp->args[i].fetch_size, regs, &len);
687                         ret += len;
688                 }
689
690         return ret;
691 }
692
693 /* Store the value of each argument */
694 static __kprobes void store_trace_args(int ent_size, struct trace_probe *tp,
695                                        struct pt_regs *regs,
696                                        u8 *data, int maxlen)
697 {
698         int i;
699         u32 end = tp->size;
700         u32 *dl;        /* Data (relative) location */
701
702         for (i = 0; i < tp->nr_args; i++) {
703                 if (unlikely(tp->args[i].fetch_size.fn)) {
704                         /*
705                          * First, we set the relative location and
706                          * maximum data length to *dl
707                          */
708                         dl = (u32 *)(data + tp->args[i].offset);
709                         *dl = make_data_rloc(maxlen, end - tp->args[i].offset);
710                         /* Then try to fetch string or dynamic array data */
711                         call_fetch(&tp->args[i].fetch, regs, dl);
712                         /* Reduce maximum length */
713                         end += get_rloc_len(*dl);
714                         maxlen -= get_rloc_len(*dl);
715                         /* Trick here, convert data_rloc to data_loc */
716                         *dl = convert_rloc_to_loc(*dl,
717                                  ent_size + tp->args[i].offset);
718                 } else
719                         /* Just fetching data normally */
720                         call_fetch(&tp->args[i].fetch, regs,
721                                    data + tp->args[i].offset);
722         }
723 }
724
725 /* Kprobe handler */
726 static __kprobes void kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)
727 {
728         struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);
729         struct kprobe_trace_entry_head *entry;
730         struct ring_buffer_event *event;
731         struct ring_buffer *buffer;
732         int size, dsize, pc;
733         unsigned long irq_flags;
734         struct ftrace_event_call *call = &tp->call;
735
736         tp->nhit++;
737
738         local_save_flags(irq_flags);
739         pc = preempt_count();
740
741         dsize = __get_data_size(tp, regs);
742         size = sizeof(*entry) + tp->size + dsize;
743
744         event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
745                                                   size, irq_flags, pc);
746         if (!event)
747                 return;
748
749         entry = ring_buffer_event_data(event);
750         entry->ip = (unsigned long)kp->addr;
751         store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
752
753         if (!filter_current_check_discard(buffer, call, entry, event))
754                 trace_buffer_unlock_commit_regs(buffer, event,
755                                                 irq_flags, pc, regs);
756 }
757
758 /* Kretprobe handler */
759 static __kprobes void kretprobe_trace_func(struct kretprobe_instance *ri,
760                                           struct pt_regs *regs)
761 {
762         struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
763         struct kretprobe_trace_entry_head *entry;
764         struct ring_buffer_event *event;
765         struct ring_buffer *buffer;
766         int size, pc, dsize;
767         unsigned long irq_flags;
768         struct ftrace_event_call *call = &tp->call;
769
770         local_save_flags(irq_flags);
771         pc = preempt_count();
772
773         dsize = __get_data_size(tp, regs);
774         size = sizeof(*entry) + tp->size + dsize;
775
776         event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
777                                                   size, irq_flags, pc);
778         if (!event)
779                 return;
780
781         entry = ring_buffer_event_data(event);
782         entry->func = (unsigned long)tp->rp.kp.addr;
783         entry->ret_ip = (unsigned long)ri->ret_addr;
784         store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
785
786         if (!filter_current_check_discard(buffer, call, entry, event))
787                 trace_buffer_unlock_commit_regs(buffer, event,
788                                                 irq_flags, pc, regs);
789 }
790
791 /* Event entry printers */
792 enum print_line_t
793 print_kprobe_event(struct trace_iterator *iter, int flags,
794                    struct trace_event *event)
795 {
796         struct kprobe_trace_entry_head *field;
797         struct trace_seq *s = &iter->seq;
798         struct trace_probe *tp;
799         u8 *data;
800         int i;
801
802         field = (struct kprobe_trace_entry_head *)iter->ent;
803         tp = container_of(event, struct trace_probe, call.event);
804
805         if (!trace_seq_printf(s, "%s: (", tp->call.name))
806                 goto partial;
807
808         if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
809                 goto partial;
810
811         if (!trace_seq_puts(s, ")"))
812                 goto partial;
813
814         data = (u8 *)&field[1];
815         for (i = 0; i < tp->nr_args; i++)
816                 if (!tp->args[i].type->print(s, tp->args[i].name,
817                                              data + tp->args[i].offset, field))
818                         goto partial;
819
820         if (!trace_seq_puts(s, "\n"))
821                 goto partial;
822
823         return TRACE_TYPE_HANDLED;
824 partial:
825         return TRACE_TYPE_PARTIAL_LINE;
826 }
827
828 enum print_line_t
829 print_kretprobe_event(struct trace_iterator *iter, int flags,
830                       struct trace_event *event)
831 {
832         struct kretprobe_trace_entry_head *field;
833         struct trace_seq *s = &iter->seq;
834         struct trace_probe *tp;
835         u8 *data;
836         int i;
837
838         field = (struct kretprobe_trace_entry_head *)iter->ent;
839         tp = container_of(event, struct trace_probe, call.event);
840
841         if (!trace_seq_printf(s, "%s: (", tp->call.name))
842                 goto partial;
843
844         if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
845                 goto partial;
846
847         if (!trace_seq_puts(s, " <- "))
848                 goto partial;
849
850         if (!seq_print_ip_sym(s, field->func, flags & ~TRACE_ITER_SYM_OFFSET))
851                 goto partial;
852
853         if (!trace_seq_puts(s, ")"))
854                 goto partial;
855
856         data = (u8 *)&field[1];
857         for (i = 0; i < tp->nr_args; i++)
858                 if (!tp->args[i].type->print(s, tp->args[i].name,
859                                              data + tp->args[i].offset, field))
860                         goto partial;
861
862         if (!trace_seq_puts(s, "\n"))
863                 goto partial;
864
865         return TRACE_TYPE_HANDLED;
866 partial:
867         return TRACE_TYPE_PARTIAL_LINE;
868 }
869
870
871 static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
872 {
873         int ret, i;
874         struct kprobe_trace_entry_head field;
875         struct trace_probe *tp = (struct trace_probe *)event_call->data;
876
877         DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
878         /* Set argument names as fields */
879         for (i = 0; i < tp->nr_args; i++) {
880                 ret = trace_define_field(event_call, tp->args[i].type->fmttype,
881                                          tp->args[i].name,
882                                          sizeof(field) + tp->args[i].offset,
883                                          tp->args[i].type->size,
884                                          tp->args[i].type->is_signed,
885                                          FILTER_OTHER);
886                 if (ret)
887                         return ret;
888         }
889         return 0;
890 }
891
892 static int kretprobe_event_define_fields(struct ftrace_event_call *event_call)
893 {
894         int ret, i;
895         struct kretprobe_trace_entry_head field;
896         struct trace_probe *tp = (struct trace_probe *)event_call->data;
897
898         DEFINE_FIELD(unsigned long, func, FIELD_STRING_FUNC, 0);
899         DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);
900         /* Set argument names as fields */
901         for (i = 0; i < tp->nr_args; i++) {
902                 ret = trace_define_field(event_call, tp->args[i].type->fmttype,
903                                          tp->args[i].name,
904                                          sizeof(field) + tp->args[i].offset,
905                                          tp->args[i].type->size,
906                                          tp->args[i].type->is_signed,
907                                          FILTER_OTHER);
908                 if (ret)
909                         return ret;
910         }
911         return 0;
912 }
913
914 static int __set_print_fmt(struct trace_probe *tp, char *buf, int len)
915 {
916         int i;
917         int pos = 0;
918
919         const char *fmt, *arg;
920
921         if (!trace_probe_is_return(tp)) {
922                 fmt = "(%lx)";
923                 arg = "REC->" FIELD_STRING_IP;
924         } else {
925                 fmt = "(%lx <- %lx)";
926                 arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
927         }
928
929         /* When len=0, we just calculate the needed length */
930 #define LEN_OR_ZERO (len ? len - pos : 0)
931
932         pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
933
934         for (i = 0; i < tp->nr_args; i++) {
935                 pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
936                                 tp->args[i].name, tp->args[i].type->fmt);
937         }
938
939         pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
940
941         for (i = 0; i < tp->nr_args; i++) {
942                 if (strcmp(tp->args[i].type->name, "string") == 0)
943                         pos += snprintf(buf + pos, LEN_OR_ZERO,
944                                         ", __get_str(%s)",
945                                         tp->args[i].name);
946                 else
947                         pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
948                                         tp->args[i].name);
949         }
950
951 #undef LEN_OR_ZERO
952
953         /* return the length of print_fmt */
954         return pos;
955 }
956
957 static int set_print_fmt(struct trace_probe *tp)
958 {
959         int len;
960         char *print_fmt;
961
962         /* First: called with 0 length to calculate the needed length */
963         len = __set_print_fmt(tp, NULL, 0);
964         print_fmt = kmalloc(len + 1, GFP_KERNEL);
965         if (!print_fmt)
966                 return -ENOMEM;
967
968         /* Second: actually write the @print_fmt */
969         __set_print_fmt(tp, print_fmt, len + 1);
970         tp->call.print_fmt = print_fmt;
971
972         return 0;
973 }
974
975 #ifdef CONFIG_PERF_EVENTS
976
977 /* Kprobe profile handler */
978 static __kprobes void kprobe_perf_func(struct kprobe *kp,
979                                          struct pt_regs *regs)
980 {
981         struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);
982         struct ftrace_event_call *call = &tp->call;
983         struct kprobe_trace_entry_head *entry;
984         struct hlist_head *head;
985         int size, __size, dsize;
986         int rctx;
987
988         dsize = __get_data_size(tp, regs);
989         __size = sizeof(*entry) + tp->size + dsize;
990         size = ALIGN(__size + sizeof(u32), sizeof(u64));
991         size -= sizeof(u32);
992         if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
993                      "profile buffer not large enough"))
994                 return;
995
996         entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
997         if (!entry)
998                 return;
999
1000         entry->ip = (unsigned long)kp->addr;
1001         memset(&entry[1], 0, dsize);
1002         store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
1003
1004         head = this_cpu_ptr(call->perf_events);
1005         perf_trace_buf_submit(entry, size, rctx,
1006                                         entry->ip, 1, regs, head, NULL);
1007 }
1008
1009 /* Kretprobe profile handler */
1010 static __kprobes void kretprobe_perf_func(struct kretprobe_instance *ri,
1011                                             struct pt_regs *regs)
1012 {
1013         struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
1014         struct ftrace_event_call *call = &tp->call;
1015         struct kretprobe_trace_entry_head *entry;
1016         struct hlist_head *head;
1017         int size, __size, dsize;
1018         int rctx;
1019
1020         dsize = __get_data_size(tp, regs);
1021         __size = sizeof(*entry) + tp->size + dsize;
1022         size = ALIGN(__size + sizeof(u32), sizeof(u64));
1023         size -= sizeof(u32);
1024         if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
1025                      "profile buffer not large enough"))
1026                 return;
1027
1028         entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
1029         if (!entry)
1030                 return;
1031
1032         entry->func = (unsigned long)tp->rp.kp.addr;
1033         entry->ret_ip = (unsigned long)ri->ret_addr;
1034         store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
1035
1036         head = this_cpu_ptr(call->perf_events);
1037         perf_trace_buf_submit(entry, size, rctx,
1038                                         entry->ret_ip, 1, regs, head, NULL);
1039 }
1040 #endif  /* CONFIG_PERF_EVENTS */
1041
1042 static __kprobes
1043 int kprobe_register(struct ftrace_event_call *event,
1044                     enum trace_reg type, void *data)
1045 {
1046         struct trace_probe *tp = (struct trace_probe *)event->data;
1047
1048         switch (type) {
1049         case TRACE_REG_REGISTER:
1050                 return enable_trace_probe(tp, TP_FLAG_TRACE);
1051         case TRACE_REG_UNREGISTER:
1052                 disable_trace_probe(tp, TP_FLAG_TRACE);
1053                 return 0;
1054
1055 #ifdef CONFIG_PERF_EVENTS
1056         case TRACE_REG_PERF_REGISTER:
1057                 return enable_trace_probe(tp, TP_FLAG_PROFILE);
1058         case TRACE_REG_PERF_UNREGISTER:
1059                 disable_trace_probe(tp, TP_FLAG_PROFILE);
1060                 return 0;
1061         case TRACE_REG_PERF_OPEN:
1062         case TRACE_REG_PERF_CLOSE:
1063         case TRACE_REG_PERF_ADD:
1064         case TRACE_REG_PERF_DEL:
1065                 return 0;
1066 #endif
1067         }
1068         return 0;
1069 }
1070
1071 static __kprobes
1072 int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs)
1073 {
1074         struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);
1075
1076         if (tp->flags & TP_FLAG_TRACE)
1077                 kprobe_trace_func(kp, regs);
1078 #ifdef CONFIG_PERF_EVENTS
1079         if (tp->flags & TP_FLAG_PROFILE)
1080                 kprobe_perf_func(kp, regs);
1081 #endif
1082         return 0;       /* We don't tweek kernel, so just return 0 */
1083 }
1084
1085 static __kprobes
1086 int kretprobe_dispatcher(struct kretprobe_instance *ri, struct pt_regs *regs)
1087 {
1088         struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
1089
1090         if (tp->flags & TP_FLAG_TRACE)
1091                 kretprobe_trace_func(ri, regs);
1092 #ifdef CONFIG_PERF_EVENTS
1093         if (tp->flags & TP_FLAG_PROFILE)
1094                 kretprobe_perf_func(ri, regs);
1095 #endif
1096         return 0;       /* We don't tweek kernel, so just return 0 */
1097 }
1098
1099 static struct trace_event_functions kretprobe_funcs = {
1100         .trace          = print_kretprobe_event
1101 };
1102
1103 static struct trace_event_functions kprobe_funcs = {
1104         .trace          = print_kprobe_event
1105 };
1106
1107 static int register_probe_event(struct trace_probe *tp)
1108 {
1109         struct ftrace_event_call *call = &tp->call;
1110         int ret;
1111
1112         /* Initialize ftrace_event_call */
1113         INIT_LIST_HEAD(&call->class->fields);
1114         if (trace_probe_is_return(tp)) {
1115                 call->event.funcs = &kretprobe_funcs;
1116                 call->class->define_fields = kretprobe_event_define_fields;
1117         } else {
1118                 call->event.funcs = &kprobe_funcs;
1119                 call->class->define_fields = kprobe_event_define_fields;
1120         }
1121         if (set_print_fmt(tp) < 0)
1122                 return -ENOMEM;
1123         ret = register_ftrace_event(&call->event);
1124         if (!ret) {
1125                 kfree(call->print_fmt);
1126                 return -ENODEV;
1127         }
1128         call->flags = 0;
1129         call->class->reg = kprobe_register;
1130         call->data = tp;
1131         ret = trace_add_event_call(call);
1132         if (ret) {
1133                 pr_info("Failed to register kprobe event: %s\n", call->name);
1134                 kfree(call->print_fmt);
1135                 unregister_ftrace_event(&call->event);
1136         }
1137         return ret;
1138 }
1139
1140 static void unregister_probe_event(struct trace_probe *tp)
1141 {
1142         /* tp->event is unregistered in trace_remove_event_call() */
1143         trace_remove_event_call(&tp->call);
1144         kfree(tp->call.print_fmt);
1145 }
1146
1147 /* Make a debugfs interface for controlling probe points */
1148 static __init int init_kprobe_trace(void)
1149 {
1150         struct dentry *d_tracer;
1151         struct dentry *entry;
1152
1153         if (register_module_notifier(&trace_probe_module_nb))
1154                 return -EINVAL;
1155
1156         d_tracer = tracing_init_dentry();
1157         if (!d_tracer)
1158                 return 0;
1159
1160         entry = debugfs_create_file("kprobe_events", 0644, d_tracer,
1161                                     NULL, &kprobe_events_ops);
1162
1163         /* Event list interface */
1164         if (!entry)
1165                 pr_warning("Could not create debugfs "
1166                            "'kprobe_events' entry\n");
1167
1168         /* Profile interface */
1169         entry = debugfs_create_file("kprobe_profile", 0444, d_tracer,
1170                                     NULL, &kprobe_profile_ops);
1171
1172         if (!entry)
1173                 pr_warning("Could not create debugfs "
1174                            "'kprobe_profile' entry\n");
1175         return 0;
1176 }
1177 fs_initcall(init_kprobe_trace);
1178
1179
1180 #ifdef CONFIG_FTRACE_STARTUP_TEST
1181
1182 /*
1183  * The "__used" keeps gcc from removing the function symbol
1184  * from the kallsyms table.
1185  */
1186 static __used int kprobe_trace_selftest_target(int a1, int a2, int a3,
1187                                                int a4, int a5, int a6)
1188 {
1189         return a1 + a2 + a3 + a4 + a5 + a6;
1190 }
1191
1192 static __init int kprobe_trace_self_tests_init(void)
1193 {
1194         int ret, warn = 0;
1195         int (*target)(int, int, int, int, int, int);
1196         struct trace_probe *tp;
1197
1198         target = kprobe_trace_selftest_target;
1199
1200         pr_info("Testing kprobe tracing: ");
1201
1202         ret = traceprobe_command("p:testprobe kprobe_trace_selftest_target "
1203                                   "$stack $stack0 +0($stack)",
1204                                   create_trace_probe);
1205         if (WARN_ON_ONCE(ret)) {
1206                 pr_warning("error on probing function entry.\n");
1207                 warn++;
1208         } else {
1209                 /* Enable trace point */
1210                 tp = find_trace_probe("testprobe", KPROBE_EVENT_SYSTEM);
1211                 if (WARN_ON_ONCE(tp == NULL)) {
1212                         pr_warning("error on getting new probe.\n");
1213                         warn++;
1214                 } else
1215                         enable_trace_probe(tp, TP_FLAG_TRACE);
1216         }
1217
1218         ret = traceprobe_command("r:testprobe2 kprobe_trace_selftest_target "
1219                                   "$retval", create_trace_probe);
1220         if (WARN_ON_ONCE(ret)) {
1221                 pr_warning("error on probing function return.\n");
1222                 warn++;
1223         } else {
1224                 /* Enable trace point */
1225                 tp = find_trace_probe("testprobe2", KPROBE_EVENT_SYSTEM);
1226                 if (WARN_ON_ONCE(tp == NULL)) {
1227                         pr_warning("error on getting new probe.\n");
1228                         warn++;
1229                 } else
1230                         enable_trace_probe(tp, TP_FLAG_TRACE);
1231         }
1232
1233         if (warn)
1234                 goto end;
1235
1236         ret = target(1, 2, 3, 4, 5, 6);
1237
1238         /* Disable trace points before removing it */
1239         tp = find_trace_probe("testprobe", KPROBE_EVENT_SYSTEM);
1240         if (WARN_ON_ONCE(tp == NULL)) {
1241                 pr_warning("error on getting test probe.\n");
1242                 warn++;
1243         } else
1244                 disable_trace_probe(tp, TP_FLAG_TRACE);
1245
1246         tp = find_trace_probe("testprobe2", KPROBE_EVENT_SYSTEM);
1247         if (WARN_ON_ONCE(tp == NULL)) {
1248                 pr_warning("error on getting 2nd test probe.\n");
1249                 warn++;
1250         } else
1251                 disable_trace_probe(tp, TP_FLAG_TRACE);
1252
1253         ret = traceprobe_command("-:testprobe", create_trace_probe);
1254         if (WARN_ON_ONCE(ret)) {
1255                 pr_warning("error on deleting a probe.\n");
1256                 warn++;
1257         }
1258
1259         ret = traceprobe_command("-:testprobe2", create_trace_probe);
1260         if (WARN_ON_ONCE(ret)) {
1261                 pr_warning("error on deleting a probe.\n");
1262                 warn++;
1263         }
1264
1265 end:
1266         release_all_trace_probes();
1267         if (warn)
1268                 pr_cont("NG: Some tests are failed. Please check them.\n");
1269         else
1270                 pr_cont("OK\n");
1271         return 0;
1272 }
1273
1274 late_initcall(kprobe_trace_self_tests_init);
1275
1276 #endif