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Linux/kernel/trace/trace_kprobe.c

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  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 struct trace_kprobe {
 31         struct list_head        list;
 32         struct kretprobe        rp;     /* Use rp.kp for kprobe use */
 33         unsigned long           nhit;
 34         const char              *symbol;        /* symbol name */
 35         struct trace_probe      tp;
 36 };
 37 
 38 #define SIZEOF_TRACE_KPROBE(n)                          \
 39         (offsetof(struct trace_kprobe, tp.args) +       \
 40         (sizeof(struct probe_arg) * (n)))
 41 
 42 
 43 static nokprobe_inline bool trace_kprobe_is_return(struct trace_kprobe *tk)
 44 {
 45         return tk->rp.handler != NULL;
 46 }
 47 
 48 static nokprobe_inline const char *trace_kprobe_symbol(struct trace_kprobe *tk)
 49 {
 50         return tk->symbol ? tk->symbol : "unknown";
 51 }
 52 
 53 static nokprobe_inline unsigned long trace_kprobe_offset(struct trace_kprobe *tk)
 54 {
 55         return tk->rp.kp.offset;
 56 }
 57 
 58 static nokprobe_inline bool trace_kprobe_has_gone(struct trace_kprobe *tk)
 59 {
 60         return !!(kprobe_gone(&tk->rp.kp));
 61 }
 62 
 63 static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk,
 64                                                  struct module *mod)
 65 {
 66         int len = strlen(mod->name);
 67         const char *name = trace_kprobe_symbol(tk);
 68         return strncmp(mod->name, name, len) == 0 && name[len] == ':';
 69 }
 70 
 71 static nokprobe_inline bool trace_kprobe_is_on_module(struct trace_kprobe *tk)
 72 {
 73         return !!strchr(trace_kprobe_symbol(tk), ':');
 74 }
 75 
 76 static int register_kprobe_event(struct trace_kprobe *tk);
 77 static int unregister_kprobe_event(struct trace_kprobe *tk);
 78 
 79 static DEFINE_MUTEX(probe_lock);
 80 static LIST_HEAD(probe_list);
 81 
 82 static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
 83 static int kretprobe_dispatcher(struct kretprobe_instance *ri,
 84                                 struct pt_regs *regs);
 85 
 86 /* Memory fetching by symbol */
 87 struct symbol_cache {
 88         char            *symbol;
 89         long            offset;
 90         unsigned long   addr;
 91 };
 92 
 93 unsigned long update_symbol_cache(struct symbol_cache *sc)
 94 {
 95         sc->addr = (unsigned long)kallsyms_lookup_name(sc->symbol);
 96 
 97         if (sc->addr)
 98                 sc->addr += sc->offset;
 99 
100         return sc->addr;
101 }
102 
103 void free_symbol_cache(struct symbol_cache *sc)
104 {
105         kfree(sc->symbol);
106         kfree(sc);
107 }
108 
109 struct symbol_cache *alloc_symbol_cache(const char *sym, long offset)
110 {
111         struct symbol_cache *sc;
112 
113         if (!sym || strlen(sym) == 0)
114                 return NULL;
115 
116         sc = kzalloc(sizeof(struct symbol_cache), GFP_KERNEL);
117         if (!sc)
118                 return NULL;
119 
120         sc->symbol = kstrdup(sym, GFP_KERNEL);
121         if (!sc->symbol) {
122                 kfree(sc);
123                 return NULL;
124         }
125         sc->offset = offset;
126         update_symbol_cache(sc);
127 
128         return sc;
129 }
130 
131 /*
132  * Kprobes-specific fetch functions
133  */
134 #define DEFINE_FETCH_stack(type)                                        \
135 static void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs,          \
136                                           void *offset, void *dest)     \
137 {                                                                       \
138         *(type *)dest = (type)regs_get_kernel_stack_nth(regs,           \
139                                 (unsigned int)((unsigned long)offset)); \
140 }                                                                       \
141 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(stack, type));
142 
143 DEFINE_BASIC_FETCH_FUNCS(stack)
144 /* No string on the stack entry */
145 #define fetch_stack_string      NULL
146 #define fetch_stack_string_size NULL
147 
148 #define DEFINE_FETCH_memory(type)                                       \
149 static void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs,         \
150                                           void *addr, void *dest)       \
151 {                                                                       \
152         type retval;                                                    \
153         if (probe_kernel_address(addr, retval))                         \
154                 *(type *)dest = 0;                                      \
155         else                                                            \
156                 *(type *)dest = retval;                                 \
157 }                                                                       \
158 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, type));
159 
160 DEFINE_BASIC_FETCH_FUNCS(memory)
161 /*
162  * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
163  * length and relative data location.
164  */
165 static void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,
166                                             void *addr, void *dest)
167 {
168         long ret;
169         int maxlen = get_rloc_len(*(u32 *)dest);
170         u8 *dst = get_rloc_data(dest);
171         u8 *src = addr;
172         mm_segment_t old_fs = get_fs();
173 
174         if (!maxlen)
175                 return;
176 
177         /*
178          * Try to get string again, since the string can be changed while
179          * probing.
180          */
181         set_fs(KERNEL_DS);
182         pagefault_disable();
183 
184         do
185                 ret = __copy_from_user_inatomic(dst++, src++, 1);
186         while (dst[-1] && ret == 0 && src - (u8 *)addr < maxlen);
187 
188         dst[-1] = '\0';
189         pagefault_enable();
190         set_fs(old_fs);
191 
192         if (ret < 0) {  /* Failed to fetch string */
193                 ((u8 *)get_rloc_data(dest))[0] = '\0';
194                 *(u32 *)dest = make_data_rloc(0, get_rloc_offs(*(u32 *)dest));
195         } else {
196                 *(u32 *)dest = make_data_rloc(src - (u8 *)addr,
197                                               get_rloc_offs(*(u32 *)dest));
198         }
199 }
200 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, string));
201 
202 /* Return the length of string -- including null terminal byte */
203 static void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
204                                                  void *addr, void *dest)
205 {
206         mm_segment_t old_fs;
207         int ret, len = 0;
208         u8 c;
209 
210         old_fs = get_fs();
211         set_fs(KERNEL_DS);
212         pagefault_disable();
213 
214         do {
215                 ret = __copy_from_user_inatomic(&c, (u8 *)addr + len, 1);
216                 len++;
217         } while (c && ret == 0 && len < MAX_STRING_SIZE);
218 
219         pagefault_enable();
220         set_fs(old_fs);
221 
222         if (ret < 0)    /* Failed to check the length */
223                 *(u32 *)dest = 0;
224         else
225                 *(u32 *)dest = len;
226 }
227 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, string_size));
228 
229 #define DEFINE_FETCH_symbol(type)                                       \
230 void FETCH_FUNC_NAME(symbol, type)(struct pt_regs *regs, void *data, void *dest)\
231 {                                                                       \
232         struct symbol_cache *sc = data;                                 \
233         if (sc->addr)                                                   \
234                 fetch_memory_##type(regs, (void *)sc->addr, dest);      \
235         else                                                            \
236                 *(type *)dest = 0;                                      \
237 }                                                                       \
238 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(symbol, type));
239 
240 DEFINE_BASIC_FETCH_FUNCS(symbol)
241 DEFINE_FETCH_symbol(string)
242 DEFINE_FETCH_symbol(string_size)
243 
244 /* kprobes don't support file_offset fetch methods */
245 #define fetch_file_offset_u8            NULL
246 #define fetch_file_offset_u16           NULL
247 #define fetch_file_offset_u32           NULL
248 #define fetch_file_offset_u64           NULL
249 #define fetch_file_offset_string        NULL
250 #define fetch_file_offset_string_size   NULL
251 
252 /* Fetch type information table */
253 const struct fetch_type kprobes_fetch_type_table[] = {
254         /* Special types */
255         [FETCH_TYPE_STRING] = __ASSIGN_FETCH_TYPE("string", string, string,
256                                         sizeof(u32), 1, "__data_loc char[]"),
257         [FETCH_TYPE_STRSIZE] = __ASSIGN_FETCH_TYPE("string_size", u32,
258                                         string_size, sizeof(u32), 0, "u32"),
259         /* Basic types */
260         ASSIGN_FETCH_TYPE(u8,  u8,  0),
261         ASSIGN_FETCH_TYPE(u16, u16, 0),
262         ASSIGN_FETCH_TYPE(u32, u32, 0),
263         ASSIGN_FETCH_TYPE(u64, u64, 0),
264         ASSIGN_FETCH_TYPE(s8,  u8,  1),
265         ASSIGN_FETCH_TYPE(s16, u16, 1),
266         ASSIGN_FETCH_TYPE(s32, u32, 1),
267         ASSIGN_FETCH_TYPE(s64, u64, 1),
268 
269         ASSIGN_FETCH_TYPE_END
270 };
271 
272 /*
273  * Allocate new trace_probe and initialize it (including kprobes).
274  */
275 static struct trace_kprobe *alloc_trace_kprobe(const char *group,
276                                              const char *event,
277                                              void *addr,
278                                              const char *symbol,
279                                              unsigned long offs,
280                                              int nargs, bool is_return)
281 {
282         struct trace_kprobe *tk;
283         int ret = -ENOMEM;
284 
285         tk = kzalloc(SIZEOF_TRACE_KPROBE(nargs), GFP_KERNEL);
286         if (!tk)
287                 return ERR_PTR(ret);
288 
289         if (symbol) {
290                 tk->symbol = kstrdup(symbol, GFP_KERNEL);
291                 if (!tk->symbol)
292                         goto error;
293                 tk->rp.kp.symbol_name = tk->symbol;
294                 tk->rp.kp.offset = offs;
295         } else
296                 tk->rp.kp.addr = addr;
297 
298         if (is_return)
299                 tk->rp.handler = kretprobe_dispatcher;
300         else
301                 tk->rp.kp.pre_handler = kprobe_dispatcher;
302 
303         if (!event || !is_good_name(event)) {
304                 ret = -EINVAL;
305                 goto error;
306         }
307 
308         tk->tp.call.class = &tk->tp.class;
309         tk->tp.call.name = kstrdup(event, GFP_KERNEL);
310         if (!tk->tp.call.name)
311                 goto error;
312 
313         if (!group || !is_good_name(group)) {
314                 ret = -EINVAL;
315                 goto error;
316         }
317 
318         tk->tp.class.system = kstrdup(group, GFP_KERNEL);
319         if (!tk->tp.class.system)
320                 goto error;
321 
322         INIT_LIST_HEAD(&tk->list);
323         INIT_LIST_HEAD(&tk->tp.files);
324         return tk;
325 error:
326         kfree(tk->tp.call.name);
327         kfree(tk->symbol);
328         kfree(tk);
329         return ERR_PTR(ret);
330 }
331 
332 static void free_trace_kprobe(struct trace_kprobe *tk)
333 {
334         int i;
335 
336         for (i = 0; i < tk->tp.nr_args; i++)
337                 traceprobe_free_probe_arg(&tk->tp.args[i]);
338 
339         kfree(tk->tp.call.class->system);
340         kfree(tk->tp.call.name);
341         kfree(tk->symbol);
342         kfree(tk);
343 }
344 
345 static struct trace_kprobe *find_trace_kprobe(const char *event,
346                                               const char *group)
347 {
348         struct trace_kprobe *tk;
349 
350         list_for_each_entry(tk, &probe_list, list)
351                 if (strcmp(ftrace_event_name(&tk->tp.call), event) == 0 &&
352                     strcmp(tk->tp.call.class->system, group) == 0)
353                         return tk;
354         return NULL;
355 }
356 
357 /*
358  * Enable trace_probe
359  * if the file is NULL, enable "perf" handler, or enable "trace" handler.
360  */
361 static int
362 enable_trace_kprobe(struct trace_kprobe *tk, struct ftrace_event_file *file)
363 {
364         int ret = 0;
365 
366         if (file) {
367                 struct event_file_link *link;
368 
369                 link = kmalloc(sizeof(*link), GFP_KERNEL);
370                 if (!link) {
371                         ret = -ENOMEM;
372                         goto out;
373                 }
374 
375                 link->file = file;
376                 list_add_tail_rcu(&link->list, &tk->tp.files);
377 
378                 tk->tp.flags |= TP_FLAG_TRACE;
379         } else
380                 tk->tp.flags |= TP_FLAG_PROFILE;
381 
382         if (trace_probe_is_registered(&tk->tp) && !trace_kprobe_has_gone(tk)) {
383                 if (trace_kprobe_is_return(tk))
384                         ret = enable_kretprobe(&tk->rp);
385                 else
386                         ret = enable_kprobe(&tk->rp.kp);
387         }
388  out:
389         return ret;
390 }
391 
392 /*
393  * Disable trace_probe
394  * if the file is NULL, disable "perf" handler, or disable "trace" handler.
395  */
396 static int
397 disable_trace_kprobe(struct trace_kprobe *tk, struct ftrace_event_file *file)
398 {
399         struct event_file_link *link = NULL;
400         int wait = 0;
401         int ret = 0;
402 
403         if (file) {
404                 link = find_event_file_link(&tk->tp, file);
405                 if (!link) {
406                         ret = -EINVAL;
407                         goto out;
408                 }
409 
410                 list_del_rcu(&link->list);
411                 wait = 1;
412                 if (!list_empty(&tk->tp.files))
413                         goto out;
414 
415                 tk->tp.flags &= ~TP_FLAG_TRACE;
416         } else
417                 tk->tp.flags &= ~TP_FLAG_PROFILE;
418 
419         if (!trace_probe_is_enabled(&tk->tp) && trace_probe_is_registered(&tk->tp)) {
420                 if (trace_kprobe_is_return(tk))
421                         disable_kretprobe(&tk->rp);
422                 else
423                         disable_kprobe(&tk->rp.kp);
424                 wait = 1;
425         }
426  out:
427         if (wait) {
428                 /*
429                  * Synchronize with kprobe_trace_func/kretprobe_trace_func
430                  * to ensure disabled (all running handlers are finished).
431                  * This is not only for kfree(), but also the caller,
432                  * trace_remove_event_call() supposes it for releasing
433                  * event_call related objects, which will be accessed in
434                  * the kprobe_trace_func/kretprobe_trace_func.
435                  */
436                 synchronize_sched();
437                 kfree(link);    /* Ignored if link == NULL */
438         }
439 
440         return ret;
441 }
442 
443 /* Internal register function - just handle k*probes and flags */
444 static int __register_trace_kprobe(struct trace_kprobe *tk)
445 {
446         int i, ret;
447 
448         if (trace_probe_is_registered(&tk->tp))
449                 return -EINVAL;
450 
451         for (i = 0; i < tk->tp.nr_args; i++)
452                 traceprobe_update_arg(&tk->tp.args[i]);
453 
454         /* Set/clear disabled flag according to tp->flag */
455         if (trace_probe_is_enabled(&tk->tp))
456                 tk->rp.kp.flags &= ~KPROBE_FLAG_DISABLED;
457         else
458                 tk->rp.kp.flags |= KPROBE_FLAG_DISABLED;
459 
460         if (trace_kprobe_is_return(tk))
461                 ret = register_kretprobe(&tk->rp);
462         else
463                 ret = register_kprobe(&tk->rp.kp);
464 
465         if (ret == 0)
466                 tk->tp.flags |= TP_FLAG_REGISTERED;
467         else {
468                 pr_warning("Could not insert probe at %s+%lu: %d\n",
469                            trace_kprobe_symbol(tk), trace_kprobe_offset(tk), ret);
470                 if (ret == -ENOENT && trace_kprobe_is_on_module(tk)) {
471                         pr_warning("This probe might be able to register after"
472                                    "target module is loaded. Continue.\n");
473                         ret = 0;
474                 } else if (ret == -EILSEQ) {
475                         pr_warning("Probing address(0x%p) is not an "
476                                    "instruction boundary.\n",
477                                    tk->rp.kp.addr);
478                         ret = -EINVAL;
479                 }
480         }
481 
482         return ret;
483 }
484 
485 /* Internal unregister function - just handle k*probes and flags */
486 static void __unregister_trace_kprobe(struct trace_kprobe *tk)
487 {
488         if (trace_probe_is_registered(&tk->tp)) {
489                 if (trace_kprobe_is_return(tk))
490                         unregister_kretprobe(&tk->rp);
491                 else
492                         unregister_kprobe(&tk->rp.kp);
493                 tk->tp.flags &= ~TP_FLAG_REGISTERED;
494                 /* Cleanup kprobe for reuse */
495                 if (tk->rp.kp.symbol_name)
496                         tk->rp.kp.addr = NULL;
497         }
498 }
499 
500 /* Unregister a trace_probe and probe_event: call with locking probe_lock */
501 static int unregister_trace_kprobe(struct trace_kprobe *tk)
502 {
503         /* Enabled event can not be unregistered */
504         if (trace_probe_is_enabled(&tk->tp))
505                 return -EBUSY;
506 
507         /* Will fail if probe is being used by ftrace or perf */
508         if (unregister_kprobe_event(tk))
509                 return -EBUSY;
510 
511         __unregister_trace_kprobe(tk);
512         list_del(&tk->list);
513 
514         return 0;
515 }
516 
517 /* Register a trace_probe and probe_event */
518 static int register_trace_kprobe(struct trace_kprobe *tk)
519 {
520         struct trace_kprobe *old_tk;
521         int ret;
522 
523         mutex_lock(&probe_lock);
524 
525         /* Delete old (same name) event if exist */
526         old_tk = find_trace_kprobe(ftrace_event_name(&tk->tp.call),
527                         tk->tp.call.class->system);
528         if (old_tk) {
529                 ret = unregister_trace_kprobe(old_tk);
530                 if (ret < 0)
531                         goto end;
532                 free_trace_kprobe(old_tk);
533         }
534 
535         /* Register new event */
536         ret = register_kprobe_event(tk);
537         if (ret) {
538                 pr_warning("Failed to register probe event(%d)\n", ret);
539                 goto end;
540         }
541 
542         /* Register k*probe */
543         ret = __register_trace_kprobe(tk);
544         if (ret < 0)
545                 unregister_kprobe_event(tk);
546         else
547                 list_add_tail(&tk->list, &probe_list);
548 
549 end:
550         mutex_unlock(&probe_lock);
551         return ret;
552 }
553 
554 /* Module notifier call back, checking event on the module */
555 static int trace_kprobe_module_callback(struct notifier_block *nb,
556                                        unsigned long val, void *data)
557 {
558         struct module *mod = data;
559         struct trace_kprobe *tk;
560         int ret;
561 
562         if (val != MODULE_STATE_COMING)
563                 return NOTIFY_DONE;
564 
565         /* Update probes on coming module */
566         mutex_lock(&probe_lock);
567         list_for_each_entry(tk, &probe_list, list) {
568                 if (trace_kprobe_within_module(tk, mod)) {
569                         /* Don't need to check busy - this should have gone. */
570                         __unregister_trace_kprobe(tk);
571                         ret = __register_trace_kprobe(tk);
572                         if (ret)
573                                 pr_warning("Failed to re-register probe %s on"
574                                            "%s: %d\n",
575                                            ftrace_event_name(&tk->tp.call),
576                                            mod->name, ret);
577                 }
578         }
579         mutex_unlock(&probe_lock);
580 
581         return NOTIFY_DONE;
582 }
583 
584 static struct notifier_block trace_kprobe_module_nb = {
585         .notifier_call = trace_kprobe_module_callback,
586         .priority = 1   /* Invoked after kprobe module callback */
587 };
588 
589 static int create_trace_kprobe(int argc, char **argv)
590 {
591         /*
592          * Argument syntax:
593          *  - Add kprobe: p[:[GRP/]EVENT] [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS]
594          *  - Add kretprobe: r[:[GRP/]EVENT] [MOD:]KSYM[+0] [FETCHARGS]
595          * Fetch args:
596          *  $retval     : fetch return value
597          *  $stack      : fetch stack address
598          *  $stackN     : fetch Nth of stack (N:0-)
599          *  @ADDR       : fetch memory at ADDR (ADDR should be in kernel)
600          *  @SYM[+|-offs] : fetch memory at SYM +|- offs (SYM is a data symbol)
601          *  %REG        : fetch register REG
602          * Dereferencing memory fetch:
603          *  +|-offs(ARG) : fetch memory at ARG +|- offs address.
604          * Alias name of args:
605          *  NAME=FETCHARG : set NAME as alias of FETCHARG.
606          * Type of args:
607          *  FETCHARG:TYPE : use TYPE instead of unsigned long.
608          */
609         struct trace_kprobe *tk;
610         int i, ret = 0;
611         bool is_return = false, is_delete = false;
612         char *symbol = NULL, *event = NULL, *group = NULL;
613         char *arg;
614         unsigned long offset = 0;
615         void *addr = NULL;
616         char buf[MAX_EVENT_NAME_LEN];
617 
618         /* argc must be >= 1 */
619         if (argv[0][0] == 'p')
620                 is_return = false;
621         else if (argv[0][0] == 'r')
622                 is_return = true;
623         else if (argv[0][0] == '-')
624                 is_delete = true;
625         else {
626                 pr_info("Probe definition must be started with 'p', 'r' or"
627                         " '-'.\n");
628                 return -EINVAL;
629         }
630 
631         if (argv[0][1] == ':') {
632                 event = &argv[0][2];
633                 if (strchr(event, '/')) {
634                         group = event;
635                         event = strchr(group, '/') + 1;
636                         event[-1] = '\0';
637                         if (strlen(group) == 0) {
638                                 pr_info("Group name is not specified\n");
639                                 return -EINVAL;
640                         }
641                 }
642                 if (strlen(event) == 0) {
643                         pr_info("Event name is not specified\n");
644                         return -EINVAL;
645                 }
646         }
647         if (!group)
648                 group = KPROBE_EVENT_SYSTEM;
649 
650         if (is_delete) {
651                 if (!event) {
652                         pr_info("Delete command needs an event name.\n");
653                         return -EINVAL;
654                 }
655                 mutex_lock(&probe_lock);
656                 tk = find_trace_kprobe(event, group);
657                 if (!tk) {
658                         mutex_unlock(&probe_lock);
659                         pr_info("Event %s/%s doesn't exist.\n", group, event);
660                         return -ENOENT;
661                 }
662                 /* delete an event */
663                 ret = unregister_trace_kprobe(tk);
664                 if (ret == 0)
665                         free_trace_kprobe(tk);
666                 mutex_unlock(&probe_lock);
667                 return ret;
668         }
669 
670         if (argc < 2) {
671                 pr_info("Probe point is not specified.\n");
672                 return -EINVAL;
673         }
674         if (isdigit(argv[1][0])) {
675                 if (is_return) {
676                         pr_info("Return probe point must be a symbol.\n");
677                         return -EINVAL;
678                 }
679                 /* an address specified */
680                 ret = kstrtoul(&argv[1][0], 0, (unsigned long *)&addr);
681                 if (ret) {
682                         pr_info("Failed to parse address.\n");
683                         return ret;
684                 }
685         } else {
686                 /* a symbol specified */
687                 symbol = argv[1];
688                 /* TODO: support .init module functions */
689                 ret = traceprobe_split_symbol_offset(symbol, &offset);
690                 if (ret) {
691                         pr_info("Failed to parse symbol.\n");
692                         return ret;
693                 }
694                 if (offset && is_return) {
695                         pr_info("Return probe must be used without offset.\n");
696                         return -EINVAL;
697                 }
698         }
699         argc -= 2; argv += 2;
700 
701         /* setup a probe */
702         if (!event) {
703                 /* Make a new event name */
704                 if (symbol)
705                         snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_%ld",
706                                  is_return ? 'r' : 'p', symbol, offset);
707                 else
708                         snprintf(buf, MAX_EVENT_NAME_LEN, "%c_0x%p",
709                                  is_return ? 'r' : 'p', addr);
710                 event = buf;
711         }
712         tk = alloc_trace_kprobe(group, event, addr, symbol, offset, argc,
713                                is_return);
714         if (IS_ERR(tk)) {
715                 pr_info("Failed to allocate trace_probe.(%d)\n",
716                         (int)PTR_ERR(tk));
717                 return PTR_ERR(tk);
718         }
719 
720         /* parse arguments */
721         ret = 0;
722         for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
723                 struct probe_arg *parg = &tk->tp.args[i];
724 
725                 /* Increment count for freeing args in error case */
726                 tk->tp.nr_args++;
727 
728                 /* Parse argument name */
729                 arg = strchr(argv[i], '=');
730                 if (arg) {
731                         *arg++ = '\0';
732                         parg->name = kstrdup(argv[i], GFP_KERNEL);
733                 } else {
734                         arg = argv[i];
735                         /* If argument name is omitted, set "argN" */
736                         snprintf(buf, MAX_EVENT_NAME_LEN, "arg%d", i + 1);
737                         parg->name = kstrdup(buf, GFP_KERNEL);
738                 }
739 
740                 if (!parg->name) {
741                         pr_info("Failed to allocate argument[%d] name.\n", i);
742                         ret = -ENOMEM;
743                         goto error;
744                 }
745 
746                 if (!is_good_name(parg->name)) {
747                         pr_info("Invalid argument[%d] name: %s\n",
748                                 i, parg->name);
749                         ret = -EINVAL;
750                         goto error;
751                 }
752 
753                 if (traceprobe_conflict_field_name(parg->name,
754                                                         tk->tp.args, i)) {
755                         pr_info("Argument[%d] name '%s' conflicts with "
756                                 "another field.\n", i, argv[i]);
757                         ret = -EINVAL;
758                         goto error;
759                 }
760 
761                 /* Parse fetch argument */
762                 ret = traceprobe_parse_probe_arg(arg, &tk->tp.size, parg,
763                                                 is_return, true);
764                 if (ret) {
765                         pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
766                         goto error;
767                 }
768         }
769 
770         ret = register_trace_kprobe(tk);
771         if (ret)
772                 goto error;
773         return 0;
774 
775 error:
776         free_trace_kprobe(tk);
777         return ret;
778 }
779 
780 static int release_all_trace_kprobes(void)
781 {
782         struct trace_kprobe *tk;
783         int ret = 0;
784 
785         mutex_lock(&probe_lock);
786         /* Ensure no probe is in use. */
787         list_for_each_entry(tk, &probe_list, list)
788                 if (trace_probe_is_enabled(&tk->tp)) {
789                         ret = -EBUSY;
790                         goto end;
791                 }
792         /* TODO: Use batch unregistration */
793         while (!list_empty(&probe_list)) {
794                 tk = list_entry(probe_list.next, struct trace_kprobe, list);
795                 ret = unregister_trace_kprobe(tk);
796                 if (ret)
797                         goto end;
798                 free_trace_kprobe(tk);
799         }
800 
801 end:
802         mutex_unlock(&probe_lock);
803 
804         return ret;
805 }
806 
807 /* Probes listing interfaces */
808 static void *probes_seq_start(struct seq_file *m, loff_t *pos)
809 {
810         mutex_lock(&probe_lock);
811         return seq_list_start(&probe_list, *pos);
812 }
813 
814 static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
815 {
816         return seq_list_next(v, &probe_list, pos);
817 }
818 
819 static void probes_seq_stop(struct seq_file *m, void *v)
820 {
821         mutex_unlock(&probe_lock);
822 }
823 
824 static int probes_seq_show(struct seq_file *m, void *v)
825 {
826         struct trace_kprobe *tk = v;
827         int i;
828 
829         seq_printf(m, "%c", trace_kprobe_is_return(tk) ? 'r' : 'p');
830         seq_printf(m, ":%s/%s", tk->tp.call.class->system,
831                         ftrace_event_name(&tk->tp.call));
832 
833         if (!tk->symbol)
834                 seq_printf(m, " 0x%p", tk->rp.kp.addr);
835         else if (tk->rp.kp.offset)
836                 seq_printf(m, " %s+%u", trace_kprobe_symbol(tk),
837                            tk->rp.kp.offset);
838         else
839                 seq_printf(m, " %s", trace_kprobe_symbol(tk));
840 
841         for (i = 0; i < tk->tp.nr_args; i++)
842                 seq_printf(m, " %s=%s", tk->tp.args[i].name, tk->tp.args[i].comm);
843         seq_printf(m, "\n");
844 
845         return 0;
846 }
847 
848 static const struct seq_operations probes_seq_op = {
849         .start  = probes_seq_start,
850         .next   = probes_seq_next,
851         .stop   = probes_seq_stop,
852         .show   = probes_seq_show
853 };
854 
855 static int probes_open(struct inode *inode, struct file *file)
856 {
857         int ret;
858 
859         if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
860                 ret = release_all_trace_kprobes();
861                 if (ret < 0)
862                         return ret;
863         }
864 
865         return seq_open(file, &probes_seq_op);
866 }
867 
868 static ssize_t probes_write(struct file *file, const char __user *buffer,
869                             size_t count, loff_t *ppos)
870 {
871         return traceprobe_probes_write(file, buffer, count, ppos,
872                         create_trace_kprobe);
873 }
874 
875 static const struct file_operations kprobe_events_ops = {
876         .owner          = THIS_MODULE,
877         .open           = probes_open,
878         .read           = seq_read,
879         .llseek         = seq_lseek,
880         .release        = seq_release,
881         .write          = probes_write,
882 };
883 
884 /* Probes profiling interfaces */
885 static int probes_profile_seq_show(struct seq_file *m, void *v)
886 {
887         struct trace_kprobe *tk = v;
888 
889         seq_printf(m, "  %-44s %15lu %15lu\n",
890                    ftrace_event_name(&tk->tp.call), tk->nhit,
891                    tk->rp.kp.nmissed);
892 
893         return 0;
894 }
895 
896 static const struct seq_operations profile_seq_op = {
897         .start  = probes_seq_start,
898         .next   = probes_seq_next,
899         .stop   = probes_seq_stop,
900         .show   = probes_profile_seq_show
901 };
902 
903 static int profile_open(struct inode *inode, struct file *file)
904 {
905         return seq_open(file, &profile_seq_op);
906 }
907 
908 static const struct file_operations kprobe_profile_ops = {
909         .owner          = THIS_MODULE,
910         .open           = profile_open,
911         .read           = seq_read,
912         .llseek         = seq_lseek,
913         .release        = seq_release,
914 };
915 
916 /* Kprobe handler */
917 static nokprobe_inline void
918 __kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs,
919                     struct ftrace_event_file *ftrace_file)
920 {
921         struct kprobe_trace_entry_head *entry;
922         struct ring_buffer_event *event;
923         struct ring_buffer *buffer;
924         int size, dsize, pc;
925         unsigned long irq_flags;
926         struct ftrace_event_call *call = &tk->tp.call;
927 
928         WARN_ON(call != ftrace_file->event_call);
929 
930         if (ftrace_trigger_soft_disabled(ftrace_file))
931                 return;
932 
933         local_save_flags(irq_flags);
934         pc = preempt_count();
935 
936         dsize = __get_data_size(&tk->tp, regs);
937         size = sizeof(*entry) + tk->tp.size + dsize;
938 
939         event = trace_event_buffer_lock_reserve(&buffer, ftrace_file,
940                                                 call->event.type,
941                                                 size, irq_flags, pc);
942         if (!event)
943                 return;
944 
945         entry = ring_buffer_event_data(event);
946         entry->ip = (unsigned long)tk->rp.kp.addr;
947         store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
948 
949         event_trigger_unlock_commit_regs(ftrace_file, buffer, event,
950                                          entry, irq_flags, pc, regs);
951 }
952 
953 static void
954 kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs)
955 {
956         struct event_file_link *link;
957 
958         list_for_each_entry_rcu(link, &tk->tp.files, list)
959                 __kprobe_trace_func(tk, regs, link->file);
960 }
961 NOKPROBE_SYMBOL(kprobe_trace_func);
962 
963 /* Kretprobe handler */
964 static nokprobe_inline void
965 __kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
966                        struct pt_regs *regs,
967                        struct ftrace_event_file *ftrace_file)
968 {
969         struct kretprobe_trace_entry_head *entry;
970         struct ring_buffer_event *event;
971         struct ring_buffer *buffer;
972         int size, pc, dsize;
973         unsigned long irq_flags;
974         struct ftrace_event_call *call = &tk->tp.call;
975 
976         WARN_ON(call != ftrace_file->event_call);
977 
978         if (ftrace_trigger_soft_disabled(ftrace_file))
979                 return;
980 
981         local_save_flags(irq_flags);
982         pc = preempt_count();
983 
984         dsize = __get_data_size(&tk->tp, regs);
985         size = sizeof(*entry) + tk->tp.size + dsize;
986 
987         event = trace_event_buffer_lock_reserve(&buffer, ftrace_file,
988                                                 call->event.type,
989                                                 size, irq_flags, pc);
990         if (!event)
991                 return;
992 
993         entry = ring_buffer_event_data(event);
994         entry->func = (unsigned long)tk->rp.kp.addr;
995         entry->ret_ip = (unsigned long)ri->ret_addr;
996         store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
997 
998         event_trigger_unlock_commit_regs(ftrace_file, buffer, event,
999                                          entry, irq_flags, pc, regs);
1000 }
1001 
1002 static void
1003 kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
1004                      struct pt_regs *regs)
1005 {
1006         struct event_file_link *link;
1007 
1008         list_for_each_entry_rcu(link, &tk->tp.files, list)
1009                 __kretprobe_trace_func(tk, ri, regs, link->file);
1010 }
1011 NOKPROBE_SYMBOL(kretprobe_trace_func);
1012 
1013 /* Event entry printers */
1014 static enum print_line_t
1015 print_kprobe_event(struct trace_iterator *iter, int flags,
1016                    struct trace_event *event)
1017 {
1018         struct kprobe_trace_entry_head *field;
1019         struct trace_seq *s = &iter->seq;
1020         struct trace_probe *tp;
1021         u8 *data;
1022         int i;
1023 
1024         field = (struct kprobe_trace_entry_head *)iter->ent;
1025         tp = container_of(event, struct trace_probe, call.event);
1026 
1027         if (!trace_seq_printf(s, "%s: (", ftrace_event_name(&tp->call)))
1028                 goto partial;
1029 
1030         if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
1031                 goto partial;
1032 
1033         if (!trace_seq_puts(s, ")"))
1034                 goto partial;
1035 
1036         data = (u8 *)&field[1];
1037         for (i = 0; i < tp->nr_args; i++)
1038                 if (!tp->args[i].type->print(s, tp->args[i].name,
1039                                              data + tp->args[i].offset, field))
1040                         goto partial;
1041 
1042         if (!trace_seq_puts(s, "\n"))
1043                 goto partial;
1044 
1045         return TRACE_TYPE_HANDLED;
1046 partial:
1047         return TRACE_TYPE_PARTIAL_LINE;
1048 }
1049 
1050 static enum print_line_t
1051 print_kretprobe_event(struct trace_iterator *iter, int flags,
1052                       struct trace_event *event)
1053 {
1054         struct kretprobe_trace_entry_head *field;
1055         struct trace_seq *s = &iter->seq;
1056         struct trace_probe *tp;
1057         u8 *data;
1058         int i;
1059 
1060         field = (struct kretprobe_trace_entry_head *)iter->ent;
1061         tp = container_of(event, struct trace_probe, call.event);
1062 
1063         if (!trace_seq_printf(s, "%s: (", ftrace_event_name(&tp->call)))
1064                 goto partial;
1065 
1066         if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
1067                 goto partial;
1068 
1069         if (!trace_seq_puts(s, " <- "))
1070                 goto partial;
1071 
1072         if (!seq_print_ip_sym(s, field->func, flags & ~TRACE_ITER_SYM_OFFSET))
1073                 goto partial;
1074 
1075         if (!trace_seq_puts(s, ")"))
1076                 goto partial;
1077 
1078         data = (u8 *)&field[1];
1079         for (i = 0; i < tp->nr_args; i++)
1080                 if (!tp->args[i].type->print(s, tp->args[i].name,
1081                                              data + tp->args[i].offset, field))
1082                         goto partial;
1083 
1084         if (!trace_seq_puts(s, "\n"))
1085                 goto partial;
1086 
1087         return TRACE_TYPE_HANDLED;
1088 partial:
1089         return TRACE_TYPE_PARTIAL_LINE;
1090 }
1091 
1092 
1093 static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
1094 {
1095         int ret, i;
1096         struct kprobe_trace_entry_head field;
1097         struct trace_kprobe *tk = (struct trace_kprobe *)event_call->data;
1098 
1099         DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
1100         /* Set argument names as fields */
1101         for (i = 0; i < tk->tp.nr_args; i++) {
1102                 struct probe_arg *parg = &tk->tp.args[i];
1103 
1104                 ret = trace_define_field(event_call, parg->type->fmttype,
1105                                          parg->name,
1106                                          sizeof(field) + parg->offset,
1107                                          parg->type->size,
1108                                          parg->type->is_signed,
1109                                          FILTER_OTHER);
1110                 if (ret)
1111                         return ret;
1112         }
1113         return 0;
1114 }
1115 
1116 static int kretprobe_event_define_fields(struct ftrace_event_call *event_call)
1117 {
1118         int ret, i;
1119         struct kretprobe_trace_entry_head field;
1120         struct trace_kprobe *tk = (struct trace_kprobe *)event_call->data;
1121 
1122         DEFINE_FIELD(unsigned long, func, FIELD_STRING_FUNC, 0);
1123         DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);
1124         /* Set argument names as fields */
1125         for (i = 0; i < tk->tp.nr_args; i++) {
1126                 struct probe_arg *parg = &tk->tp.args[i];
1127 
1128                 ret = trace_define_field(event_call, parg->type->fmttype,
1129                                          parg->name,
1130                                          sizeof(field) + parg->offset,
1131                                          parg->type->size,
1132                                          parg->type->is_signed,
1133                                          FILTER_OTHER);
1134                 if (ret)
1135                         return ret;
1136         }
1137         return 0;
1138 }
1139 
1140 #ifdef CONFIG_PERF_EVENTS
1141 
1142 /* Kprobe profile handler */
1143 static void
1144 kprobe_perf_func(struct trace_kprobe *tk, struct pt_regs *regs)
1145 {
1146         struct ftrace_event_call *call = &tk->tp.call;
1147         struct kprobe_trace_entry_head *entry;
1148         struct hlist_head *head;
1149         int size, __size, dsize;
1150         int rctx;
1151 
1152         head = this_cpu_ptr(call->perf_events);
1153         if (hlist_empty(head))
1154                 return;
1155 
1156         dsize = __get_data_size(&tk->tp, regs);
1157         __size = sizeof(*entry) + tk->tp.size + dsize;
1158         size = ALIGN(__size + sizeof(u32), sizeof(u64));
1159         size -= sizeof(u32);
1160 
1161         entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
1162         if (!entry)
1163                 return;
1164 
1165         entry->ip = (unsigned long)tk->rp.kp.addr;
1166         memset(&entry[1], 0, dsize);
1167         store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
1168         perf_trace_buf_submit(entry, size, rctx, 0, 1, regs, head, NULL);
1169 }
1170 NOKPROBE_SYMBOL(kprobe_perf_func);
1171 
1172 /* Kretprobe profile handler */
1173 static void
1174 kretprobe_perf_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
1175                     struct pt_regs *regs)
1176 {
1177         struct ftrace_event_call *call = &tk->tp.call;
1178         struct kretprobe_trace_entry_head *entry;
1179         struct hlist_head *head;
1180         int size, __size, dsize;
1181         int rctx;
1182 
1183         head = this_cpu_ptr(call->perf_events);
1184         if (hlist_empty(head))
1185                 return;
1186 
1187         dsize = __get_data_size(&tk->tp, regs);
1188         __size = sizeof(*entry) + tk->tp.size + dsize;
1189         size = ALIGN(__size + sizeof(u32), sizeof(u64));
1190         size -= sizeof(u32);
1191 
1192         entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
1193         if (!entry)
1194                 return;
1195 
1196         entry->func = (unsigned long)tk->rp.kp.addr;
1197         entry->ret_ip = (unsigned long)ri->ret_addr;
1198         store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
1199         perf_trace_buf_submit(entry, size, rctx, 0, 1, regs, head, NULL);
1200 }
1201 NOKPROBE_SYMBOL(kretprobe_perf_func);
1202 #endif  /* CONFIG_PERF_EVENTS */
1203 
1204 /*
1205  * called by perf_trace_init() or __ftrace_set_clr_event() under event_mutex.
1206  *
1207  * kprobe_trace_self_tests_init() does enable_trace_probe/disable_trace_probe
1208  * lockless, but we can't race with this __init function.
1209  */
1210 static int kprobe_register(struct ftrace_event_call *event,
1211                            enum trace_reg type, void *data)
1212 {
1213         struct trace_kprobe *tk = (struct trace_kprobe *)event->data;
1214         struct ftrace_event_file *file = data;
1215 
1216         switch (type) {
1217         case TRACE_REG_REGISTER:
1218                 return enable_trace_kprobe(tk, file);
1219         case TRACE_REG_UNREGISTER:
1220                 return disable_trace_kprobe(tk, file);
1221 
1222 #ifdef CONFIG_PERF_EVENTS
1223         case TRACE_REG_PERF_REGISTER:
1224                 return enable_trace_kprobe(tk, NULL);
1225         case TRACE_REG_PERF_UNREGISTER:
1226                 return disable_trace_kprobe(tk, NULL);
1227         case TRACE_REG_PERF_OPEN:
1228         case TRACE_REG_PERF_CLOSE:
1229         case TRACE_REG_PERF_ADD:
1230         case TRACE_REG_PERF_DEL:
1231                 return 0;
1232 #endif
1233         }
1234         return 0;
1235 }
1236 
1237 static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs)
1238 {
1239         struct trace_kprobe *tk = container_of(kp, struct trace_kprobe, rp.kp);
1240 
1241         tk->nhit++;
1242 
1243         if (tk->tp.flags & TP_FLAG_TRACE)
1244                 kprobe_trace_func(tk, regs);
1245 #ifdef CONFIG_PERF_EVENTS
1246         if (tk->tp.flags & TP_FLAG_PROFILE)
1247                 kprobe_perf_func(tk, regs);
1248 #endif
1249         return 0;       /* We don't tweek kernel, so just return 0 */
1250 }
1251 NOKPROBE_SYMBOL(kprobe_dispatcher);
1252 
1253 static int
1254 kretprobe_dispatcher(struct kretprobe_instance *ri, struct pt_regs *regs)
1255 {
1256         struct trace_kprobe *tk = container_of(ri->rp, struct trace_kprobe, rp);
1257 
1258         tk->nhit++;
1259 
1260         if (tk->tp.flags & TP_FLAG_TRACE)
1261                 kretprobe_trace_func(tk, ri, regs);
1262 #ifdef CONFIG_PERF_EVENTS
1263         if (tk->tp.flags & TP_FLAG_PROFILE)
1264                 kretprobe_perf_func(tk, ri, regs);
1265 #endif
1266         return 0;       /* We don't tweek kernel, so just return 0 */
1267 }
1268 NOKPROBE_SYMBOL(kretprobe_dispatcher);
1269 
1270 static struct trace_event_functions kretprobe_funcs = {
1271         .trace          = print_kretprobe_event
1272 };
1273 
1274 static struct trace_event_functions kprobe_funcs = {
1275         .trace          = print_kprobe_event
1276 };
1277 
1278 static int register_kprobe_event(struct trace_kprobe *tk)
1279 {
1280         struct ftrace_event_call *call = &tk->tp.call;
1281         int ret;
1282 
1283         /* Initialize ftrace_event_call */
1284         INIT_LIST_HEAD(&call->class->fields);
1285         if (trace_kprobe_is_return(tk)) {
1286                 call->event.funcs = &kretprobe_funcs;
1287                 call->class->define_fields = kretprobe_event_define_fields;
1288         } else {
1289                 call->event.funcs = &kprobe_funcs;
1290                 call->class->define_fields = kprobe_event_define_fields;
1291         }
1292         if (set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0)
1293                 return -ENOMEM;
1294         ret = register_ftrace_event(&call->event);
1295         if (!ret) {
1296                 kfree(call->print_fmt);
1297                 return -ENODEV;
1298         }
1299         call->flags = 0;
1300         call->class->reg = kprobe_register;
1301         call->data = tk;
1302         ret = trace_add_event_call(call);
1303         if (ret) {
1304                 pr_info("Failed to register kprobe event: %s\n",
1305                         ftrace_event_name(call));
1306                 kfree(call->print_fmt);
1307                 unregister_ftrace_event(&call->event);
1308         }
1309         return ret;
1310 }
1311 
1312 static int unregister_kprobe_event(struct trace_kprobe *tk)
1313 {
1314         int ret;
1315 
1316         /* tp->event is unregistered in trace_remove_event_call() */
1317         ret = trace_remove_event_call(&tk->tp.call);
1318         if (!ret)
1319                 kfree(tk->tp.call.print_fmt);
1320         return ret;
1321 }
1322 
1323 /* Make a debugfs interface for controlling probe points */
1324 static __init int init_kprobe_trace(void)
1325 {
1326         struct dentry *d_tracer;
1327         struct dentry *entry;
1328 
1329         if (register_module_notifier(&trace_kprobe_module_nb))
1330                 return -EINVAL;
1331 
1332         d_tracer = tracing_init_dentry();
1333         if (!d_tracer)
1334                 return 0;
1335 
1336         entry = debugfs_create_file("kprobe_events", 0644, d_tracer,
1337                                     NULL, &kprobe_events_ops);
1338 
1339         /* Event list interface */
1340         if (!entry)
1341                 pr_warning("Could not create debugfs "
1342                            "'kprobe_events' entry\n");
1343 
1344         /* Profile interface */
1345         entry = debugfs_create_file("kprobe_profile", 0444, d_tracer,
1346                                     NULL, &kprobe_profile_ops);
1347 
1348         if (!entry)
1349                 pr_warning("Could not create debugfs "
1350                            "'kprobe_profile' entry\n");
1351         return 0;
1352 }
1353 fs_initcall(init_kprobe_trace);
1354 
1355 
1356 #ifdef CONFIG_FTRACE_STARTUP_TEST
1357 
1358 /*
1359  * The "__used" keeps gcc from removing the function symbol
1360  * from the kallsyms table.
1361  */
1362 static __used int kprobe_trace_selftest_target(int a1, int a2, int a3,
1363                                                int a4, int a5, int a6)
1364 {
1365         return a1 + a2 + a3 + a4 + a5 + a6;
1366 }
1367 
1368 static struct ftrace_event_file *
1369 find_trace_probe_file(struct trace_kprobe *tk, struct trace_array *tr)
1370 {
1371         struct ftrace_event_file *file;
1372 
1373         list_for_each_entry(file, &tr->events, list)
1374                 if (file->event_call == &tk->tp.call)
1375                         return file;
1376 
1377         return NULL;
1378 }
1379 
1380 /*
1381  * Nobody but us can call enable_trace_kprobe/disable_trace_kprobe at this
1382  * stage, we can do this lockless.
1383  */
1384 static __init int kprobe_trace_self_tests_init(void)
1385 {
1386         int ret, warn = 0;
1387         int (*target)(int, int, int, int, int, int);
1388         struct trace_kprobe *tk;
1389         struct ftrace_event_file *file;
1390 
1391         if (tracing_is_disabled())
1392                 return -ENODEV;
1393 
1394         target = kprobe_trace_selftest_target;
1395 
1396         pr_info("Testing kprobe tracing: ");
1397 
1398         ret = traceprobe_command("p:testprobe kprobe_trace_selftest_target "
1399                                   "$stack $stack0 +0($stack)",
1400                                   create_trace_kprobe);
1401         if (WARN_ON_ONCE(ret)) {
1402                 pr_warn("error on probing function entry.\n");
1403                 warn++;
1404         } else {
1405                 /* Enable trace point */
1406                 tk = find_trace_kprobe("testprobe", KPROBE_EVENT_SYSTEM);
1407                 if (WARN_ON_ONCE(tk == NULL)) {
1408                         pr_warn("error on getting new probe.\n");
1409                         warn++;
1410                 } else {
1411                         file = find_trace_probe_file(tk, top_trace_array());
1412                         if (WARN_ON_ONCE(file == NULL)) {
1413                                 pr_warn("error on getting probe file.\n");
1414                                 warn++;
1415                         } else
1416                                 enable_trace_kprobe(tk, file);
1417                 }
1418         }
1419 
1420         ret = traceprobe_command("r:testprobe2 kprobe_trace_selftest_target "
1421                                   "$retval", create_trace_kprobe);
1422         if (WARN_ON_ONCE(ret)) {
1423                 pr_warn("error on probing function return.\n");
1424                 warn++;
1425         } else {
1426                 /* Enable trace point */
1427                 tk = find_trace_kprobe("testprobe2", KPROBE_EVENT_SYSTEM);
1428                 if (WARN_ON_ONCE(tk == NULL)) {
1429                         pr_warn("error on getting 2nd new probe.\n");
1430                         warn++;
1431                 } else {
1432                         file = find_trace_probe_file(tk, top_trace_array());
1433                         if (WARN_ON_ONCE(file == NULL)) {
1434                                 pr_warn("error on getting probe file.\n");
1435                                 warn++;
1436                         } else
1437                                 enable_trace_kprobe(tk, file);
1438                 }
1439         }
1440 
1441         if (warn)
1442                 goto end;
1443 
1444         ret = target(1, 2, 3, 4, 5, 6);
1445 
1446         /* Disable trace points before removing it */
1447         tk = find_trace_kprobe("testprobe", KPROBE_EVENT_SYSTEM);
1448         if (WARN_ON_ONCE(tk == NULL)) {
1449                 pr_warn("error on getting test probe.\n");
1450                 warn++;
1451         } else {
1452                 file = find_trace_probe_file(tk, top_trace_array());
1453                 if (WARN_ON_ONCE(file == NULL)) {
1454                         pr_warn("error on getting probe file.\n");
1455                         warn++;
1456                 } else
1457                         disable_trace_kprobe(tk, file);
1458         }
1459 
1460         tk = find_trace_kprobe("testprobe2", KPROBE_EVENT_SYSTEM);
1461         if (WARN_ON_ONCE(tk == NULL)) {
1462                 pr_warn("error on getting 2nd test probe.\n");
1463                 warn++;
1464         } else {
1465                 file = find_trace_probe_file(tk, top_trace_array());
1466                 if (WARN_ON_ONCE(file == NULL)) {
1467                         pr_warn("error on getting probe file.\n");
1468                         warn++;
1469                 } else
1470                         disable_trace_kprobe(tk, file);
1471         }
1472 
1473         ret = traceprobe_command("-:testprobe", create_trace_kprobe);
1474         if (WARN_ON_ONCE(ret)) {
1475                 pr_warn("error on deleting a probe.\n");
1476                 warn++;
1477         }
1478 
1479         ret = traceprobe_command("-:testprobe2", create_trace_kprobe);
1480         if (WARN_ON_ONCE(ret)) {
1481                 pr_warn("error on deleting a probe.\n");
1482                 warn++;
1483         }
1484 
1485 end:
1486         release_all_trace_kprobes();
1487         if (warn)
1488                 pr_cont("NG: Some tests are failed. Please check them.\n");
1489         else
1490                 pr_cont("OK\n");
1491         return 0;
1492 }
1493 
1494 late_initcall(kprobe_trace_self_tests_init);
1495 
1496 #endif
1497 

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