1f4f9b9d5c899969d393c54bacc7b4c99e1584ea
[linux-2.6.git] / kernel / kprobes.c
1 /*
2  *  Kernel Probes (KProbes)
3  *  kernel/kprobes.c
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License as published by
7  * the Free Software Foundation; either version 2 of the License, or
8  * (at your option) any later version.
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  * Copyright (C) IBM Corporation, 2002, 2004
20  *
21  * 2002-Oct     Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
22  *              Probes initial implementation (includes suggestions from
23  *              Rusty Russell).
24  * 2004-Aug     Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with
25  *              hlists and exceptions notifier as suggested by Andi Kleen.
26  * 2004-July    Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
27  *              interface to access function arguments.
28  * 2004-Sep     Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
29  *              exceptions notifier to be first on the priority list.
30  * 2005-May     Hien Nguyen <hien@us.ibm.com>, Jim Keniston
31  *              <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
32  *              <prasanna@in.ibm.com> added function-return probes.
33  */
34 #include <linux/kprobes.h>
35 #include <linux/hash.h>
36 #include <linux/init.h>
37 #include <linux/slab.h>
38 #include <linux/stddef.h>
39 #include <linux/module.h>
40 #include <linux/moduleloader.h>
41 #include <linux/kallsyms.h>
42 #include <linux/freezer.h>
43 #include <linux/seq_file.h>
44 #include <linux/debugfs.h>
45 #include <linux/sysctl.h>
46 #include <linux/kdebug.h>
47 #include <linux/memory.h>
48 #include <linux/ftrace.h>
49 #include <linux/cpu.h>
50 #include <linux/jump_label.h>
51
52 #include <asm-generic/sections.h>
53 #include <asm/cacheflush.h>
54 #include <asm/errno.h>
55 #include <asm/uaccess.h>
56
57 #define KPROBE_HASH_BITS 6
58 #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
59
60
61 /*
62  * Some oddball architectures like 64bit powerpc have function descriptors
63  * so this must be overridable.
64  */
65 #ifndef kprobe_lookup_name
66 #define kprobe_lookup_name(name, addr) \
67         addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name)))
68 #endif
69
70 static int kprobes_initialized;
71 static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
72 static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
73
74 /* NOTE: change this value only with kprobe_mutex held */
75 static bool kprobes_all_disarmed;
76
77 /* This protects kprobe_table and optimizing_list */
78 static DEFINE_MUTEX(kprobe_mutex);
79 static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
80 static struct {
81         spinlock_t lock ____cacheline_aligned_in_smp;
82 } kretprobe_table_locks[KPROBE_TABLE_SIZE];
83
84 static spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
85 {
86         return &(kretprobe_table_locks[hash].lock);
87 }
88
89 /*
90  * Normally, functions that we'd want to prohibit kprobes in, are marked
91  * __kprobes. But, there are cases where such functions already belong to
92  * a different section (__sched for preempt_schedule)
93  *
94  * For such cases, we now have a blacklist
95  */
96 static struct kprobe_blackpoint kprobe_blacklist[] = {
97         {"preempt_schedule",},
98         {"native_get_debugreg",},
99         {"irq_entries_start",},
100         {"common_interrupt",},
101         {"mcount",},    /* mcount can be called from everywhere */
102         {NULL}    /* Terminator */
103 };
104
105 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
106 /*
107  * kprobe->ainsn.insn points to the copy of the instruction to be
108  * single-stepped. x86_64, POWER4 and above have no-exec support and
109  * stepping on the instruction on a vmalloced/kmalloced/data page
110  * is a recipe for disaster
111  */
112 struct kprobe_insn_page {
113         struct list_head list;
114         kprobe_opcode_t *insns;         /* Page of instruction slots */
115         int nused;
116         int ngarbage;
117         char slot_used[];
118 };
119
120 #define KPROBE_INSN_PAGE_SIZE(slots)                    \
121         (offsetof(struct kprobe_insn_page, slot_used) + \
122          (sizeof(char) * (slots)))
123
124 struct kprobe_insn_cache {
125         struct list_head pages; /* list of kprobe_insn_page */
126         size_t insn_size;       /* size of instruction slot */
127         int nr_garbage;
128 };
129
130 static int slots_per_page(struct kprobe_insn_cache *c)
131 {
132         return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));
133 }
134
135 enum kprobe_slot_state {
136         SLOT_CLEAN = 0,
137         SLOT_DIRTY = 1,
138         SLOT_USED = 2,
139 };
140
141 static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_slots */
142 static struct kprobe_insn_cache kprobe_insn_slots = {
143         .pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
144         .insn_size = MAX_INSN_SIZE,
145         .nr_garbage = 0,
146 };
147 static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c);
148
149 /**
150  * __get_insn_slot() - Find a slot on an executable page for an instruction.
151  * We allocate an executable page if there's no room on existing ones.
152  */
153 static kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
154 {
155         struct kprobe_insn_page *kip;
156
157  retry:
158         list_for_each_entry(kip, &c->pages, list) {
159                 if (kip->nused < slots_per_page(c)) {
160                         int i;
161                         for (i = 0; i < slots_per_page(c); i++) {
162                                 if (kip->slot_used[i] == SLOT_CLEAN) {
163                                         kip->slot_used[i] = SLOT_USED;
164                                         kip->nused++;
165                                         return kip->insns + (i * c->insn_size);
166                                 }
167                         }
168                         /* kip->nused is broken. Fix it. */
169                         kip->nused = slots_per_page(c);
170                         WARN_ON(1);
171                 }
172         }
173
174         /* If there are any garbage slots, collect it and try again. */
175         if (c->nr_garbage && collect_garbage_slots(c) == 0)
176                 goto retry;
177
178         /* All out of space.  Need to allocate a new page. */
179         kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
180         if (!kip)
181                 return NULL;
182
183         /*
184          * Use module_alloc so this page is within +/- 2GB of where the
185          * kernel image and loaded module images reside. This is required
186          * so x86_64 can correctly handle the %rip-relative fixups.
187          */
188         kip->insns = module_alloc(PAGE_SIZE);
189         if (!kip->insns) {
190                 kfree(kip);
191                 return NULL;
192         }
193         INIT_LIST_HEAD(&kip->list);
194         memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c));
195         kip->slot_used[0] = SLOT_USED;
196         kip->nused = 1;
197         kip->ngarbage = 0;
198         list_add(&kip->list, &c->pages);
199         return kip->insns;
200 }
201
202
203 kprobe_opcode_t __kprobes *get_insn_slot(void)
204 {
205         kprobe_opcode_t *ret = NULL;
206
207         mutex_lock(&kprobe_insn_mutex);
208         ret = __get_insn_slot(&kprobe_insn_slots);
209         mutex_unlock(&kprobe_insn_mutex);
210
211         return ret;
212 }
213
214 /* Return 1 if all garbages are collected, otherwise 0. */
215 static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
216 {
217         kip->slot_used[idx] = SLOT_CLEAN;
218         kip->nused--;
219         if (kip->nused == 0) {
220                 /*
221                  * Page is no longer in use.  Free it unless
222                  * it's the last one.  We keep the last one
223                  * so as not to have to set it up again the
224                  * next time somebody inserts a probe.
225                  */
226                 if (!list_is_singular(&kip->list)) {
227                         list_del(&kip->list);
228                         module_free(NULL, kip->insns);
229                         kfree(kip);
230                 }
231                 return 1;
232         }
233         return 0;
234 }
235
236 static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c)
237 {
238         struct kprobe_insn_page *kip, *next;
239
240         /* Ensure no-one is interrupted on the garbages */
241         synchronize_sched();
242
243         list_for_each_entry_safe(kip, next, &c->pages, list) {
244                 int i;
245                 if (kip->ngarbage == 0)
246                         continue;
247                 kip->ngarbage = 0;      /* we will collect all garbages */
248                 for (i = 0; i < slots_per_page(c); i++) {
249                         if (kip->slot_used[i] == SLOT_DIRTY &&
250                             collect_one_slot(kip, i))
251                                 break;
252                 }
253         }
254         c->nr_garbage = 0;
255         return 0;
256 }
257
258 static void __kprobes __free_insn_slot(struct kprobe_insn_cache *c,
259                                        kprobe_opcode_t *slot, int dirty)
260 {
261         struct kprobe_insn_page *kip;
262
263         list_for_each_entry(kip, &c->pages, list) {
264                 long idx = ((long)slot - (long)kip->insns) /
265                                 (c->insn_size * sizeof(kprobe_opcode_t));
266                 if (idx >= 0 && idx < slots_per_page(c)) {
267                         WARN_ON(kip->slot_used[idx] != SLOT_USED);
268                         if (dirty) {
269                                 kip->slot_used[idx] = SLOT_DIRTY;
270                                 kip->ngarbage++;
271                                 if (++c->nr_garbage > slots_per_page(c))
272                                         collect_garbage_slots(c);
273                         } else
274                                 collect_one_slot(kip, idx);
275                         return;
276                 }
277         }
278         /* Could not free this slot. */
279         WARN_ON(1);
280 }
281
282 void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
283 {
284         mutex_lock(&kprobe_insn_mutex);
285         __free_insn_slot(&kprobe_insn_slots, slot, dirty);
286         mutex_unlock(&kprobe_insn_mutex);
287 }
288 #ifdef CONFIG_OPTPROBES
289 /* For optimized_kprobe buffer */
290 static DEFINE_MUTEX(kprobe_optinsn_mutex); /* Protects kprobe_optinsn_slots */
291 static struct kprobe_insn_cache kprobe_optinsn_slots = {
292         .pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
293         /* .insn_size is initialized later */
294         .nr_garbage = 0,
295 };
296 /* Get a slot for optimized_kprobe buffer */
297 kprobe_opcode_t __kprobes *get_optinsn_slot(void)
298 {
299         kprobe_opcode_t *ret = NULL;
300
301         mutex_lock(&kprobe_optinsn_mutex);
302         ret = __get_insn_slot(&kprobe_optinsn_slots);
303         mutex_unlock(&kprobe_optinsn_mutex);
304
305         return ret;
306 }
307
308 void __kprobes free_optinsn_slot(kprobe_opcode_t * slot, int dirty)
309 {
310         mutex_lock(&kprobe_optinsn_mutex);
311         __free_insn_slot(&kprobe_optinsn_slots, slot, dirty);
312         mutex_unlock(&kprobe_optinsn_mutex);
313 }
314 #endif
315 #endif
316
317 /* We have preemption disabled.. so it is safe to use __ versions */
318 static inline void set_kprobe_instance(struct kprobe *kp)
319 {
320         __get_cpu_var(kprobe_instance) = kp;
321 }
322
323 static inline void reset_kprobe_instance(void)
324 {
325         __get_cpu_var(kprobe_instance) = NULL;
326 }
327
328 /*
329  * This routine is called either:
330  *      - under the kprobe_mutex - during kprobe_[un]register()
331  *                              OR
332  *      - with preemption disabled - from arch/xxx/kernel/kprobes.c
333  */
334 struct kprobe __kprobes *get_kprobe(void *addr)
335 {
336         struct hlist_head *head;
337         struct hlist_node *node;
338         struct kprobe *p;
339
340         head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
341         hlist_for_each_entry_rcu(p, node, head, hlist) {
342                 if (p->addr == addr)
343                         return p;
344         }
345
346         return NULL;
347 }
348
349 static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs);
350
351 /* Return true if the kprobe is an aggregator */
352 static inline int kprobe_aggrprobe(struct kprobe *p)
353 {
354         return p->pre_handler == aggr_pre_handler;
355 }
356
357 /*
358  * Keep all fields in the kprobe consistent
359  */
360 static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p)
361 {
362         memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t));
363         memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn));
364 }
365
366 #ifdef CONFIG_OPTPROBES
367 /* NOTE: change this value only with kprobe_mutex held */
368 static bool kprobes_allow_optimization;
369
370 /*
371  * Call all pre_handler on the list, but ignores its return value.
372  * This must be called from arch-dep optimized caller.
373  */
374 void __kprobes opt_pre_handler(struct kprobe *p, struct pt_regs *regs)
375 {
376         struct kprobe *kp;
377
378         list_for_each_entry_rcu(kp, &p->list, list) {
379                 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
380                         set_kprobe_instance(kp);
381                         kp->pre_handler(kp, regs);
382                 }
383                 reset_kprobe_instance();
384         }
385 }
386
387 /* Return true(!0) if the kprobe is ready for optimization. */
388 static inline int kprobe_optready(struct kprobe *p)
389 {
390         struct optimized_kprobe *op;
391
392         if (kprobe_aggrprobe(p)) {
393                 op = container_of(p, struct optimized_kprobe, kp);
394                 return arch_prepared_optinsn(&op->optinsn);
395         }
396
397         return 0;
398 }
399
400 /*
401  * Return an optimized kprobe whose optimizing code replaces
402  * instructions including addr (exclude breakpoint).
403  */
404 static struct kprobe *__kprobes get_optimized_kprobe(unsigned long addr)
405 {
406         int i;
407         struct kprobe *p = NULL;
408         struct optimized_kprobe *op;
409
410         /* Don't check i == 0, since that is a breakpoint case. */
411         for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH; i++)
412                 p = get_kprobe((void *)(addr - i));
413
414         if (p && kprobe_optready(p)) {
415                 op = container_of(p, struct optimized_kprobe, kp);
416                 if (arch_within_optimized_kprobe(op, addr))
417                         return p;
418         }
419
420         return NULL;
421 }
422
423 /* Optimization staging list, protected by kprobe_mutex */
424 static LIST_HEAD(optimizing_list);
425
426 static void kprobe_optimizer(struct work_struct *work);
427 static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
428 #define OPTIMIZE_DELAY 5
429
430 /*
431  * Optimize (replace a breakpoint with a jump) kprobes listed on
432  * optimizing_list.
433  */
434 static __kprobes void do_optimize_kprobes(void)
435 {
436         struct optimized_kprobe *op, *tmp;
437
438         /*
439          * The optimization/unoptimization refers online_cpus via
440          * stop_machine() and cpu-hotplug modifies online_cpus.
441          * And same time, text_mutex will be held in cpu-hotplug and here.
442          * This combination can cause a deadlock (cpu-hotplug try to lock
443          * text_mutex but stop_machine can not be done because online_cpus
444          * has been changed)
445          * To avoid this deadlock, we need to call get_online_cpus()
446          * for preventing cpu-hotplug outside of text_mutex locking.
447          */
448         get_online_cpus();
449         mutex_lock(&text_mutex);
450         list_for_each_entry_safe(op, tmp, &optimizing_list, list) {
451                 WARN_ON(kprobe_disabled(&op->kp));
452                 if (arch_optimize_kprobe(op) < 0)
453                         op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
454                 list_del_init(&op->list);
455         }
456         mutex_unlock(&text_mutex);
457         put_online_cpus();
458 }
459
460 /* Kprobe jump optimizer */
461 static __kprobes void kprobe_optimizer(struct work_struct *work)
462 {
463         /* Lock modules while optimizing kprobes */
464         mutex_lock(&module_mutex);
465         mutex_lock(&kprobe_mutex);
466         if (kprobes_all_disarmed || !kprobes_allow_optimization)
467                 goto end;
468
469         /*
470          * Wait for quiesence period to ensure all running interrupts
471          * are done. Because optprobe may modify multiple instructions
472          * there is a chance that Nth instruction is interrupted. In that
473          * case, running interrupt can return to 2nd-Nth byte of jump
474          * instruction. This wait is for avoiding it.
475          */
476         synchronize_sched();
477
478         do_optimize_kprobes();
479 end:
480         mutex_unlock(&kprobe_mutex);
481         mutex_unlock(&module_mutex);
482 }
483
484 /* Optimize kprobe if p is ready to be optimized */
485 static __kprobes void optimize_kprobe(struct kprobe *p)
486 {
487         struct optimized_kprobe *op;
488
489         /* Check if the kprobe is disabled or not ready for optimization. */
490         if (!kprobe_optready(p) || !kprobes_allow_optimization ||
491             (kprobe_disabled(p) || kprobes_all_disarmed))
492                 return;
493
494         /* Both of break_handler and post_handler are not supported. */
495         if (p->break_handler || p->post_handler)
496                 return;
497
498         op = container_of(p, struct optimized_kprobe, kp);
499
500         /* Check there is no other kprobes at the optimized instructions */
501         if (arch_check_optimized_kprobe(op) < 0)
502                 return;
503
504         /* Check if it is already optimized. */
505         if (op->kp.flags & KPROBE_FLAG_OPTIMIZED)
506                 return;
507
508         op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
509         list_add(&op->list, &optimizing_list);
510         if (!delayed_work_pending(&optimizing_work))
511                 schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
512 }
513
514 /* Unoptimize a kprobe if p is optimized */
515 static __kprobes void unoptimize_kprobe(struct kprobe *p)
516 {
517         struct optimized_kprobe *op;
518
519         if ((p->flags & KPROBE_FLAG_OPTIMIZED) && kprobe_aggrprobe(p)) {
520                 op = container_of(p, struct optimized_kprobe, kp);
521                 if (!list_empty(&op->list))
522                         /* Dequeue from the optimization queue */
523                         list_del_init(&op->list);
524                 else
525                         /* Replace jump with break */
526                         arch_unoptimize_kprobe(op);
527                 op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
528         }
529 }
530
531 /* Remove optimized instructions */
532 static void __kprobes kill_optimized_kprobe(struct kprobe *p)
533 {
534         struct optimized_kprobe *op;
535
536         op = container_of(p, struct optimized_kprobe, kp);
537         if (!list_empty(&op->list)) {
538                 /* Dequeue from the optimization queue */
539                 list_del_init(&op->list);
540                 op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
541         }
542         /* Don't unoptimize, because the target code will be freed. */
543         arch_remove_optimized_kprobe(op);
544 }
545
546 /* Try to prepare optimized instructions */
547 static __kprobes void prepare_optimized_kprobe(struct kprobe *p)
548 {
549         struct optimized_kprobe *op;
550
551         op = container_of(p, struct optimized_kprobe, kp);
552         arch_prepare_optimized_kprobe(op);
553 }
554
555 /* Free optimized instructions and optimized_kprobe */
556 static __kprobes void free_aggr_kprobe(struct kprobe *p)
557 {
558         struct optimized_kprobe *op;
559
560         op = container_of(p, struct optimized_kprobe, kp);
561         arch_remove_optimized_kprobe(op);
562         kfree(op);
563 }
564
565 /* Allocate new optimized_kprobe and try to prepare optimized instructions */
566 static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
567 {
568         struct optimized_kprobe *op;
569
570         op = kzalloc(sizeof(struct optimized_kprobe), GFP_KERNEL);
571         if (!op)
572                 return NULL;
573
574         INIT_LIST_HEAD(&op->list);
575         op->kp.addr = p->addr;
576         arch_prepare_optimized_kprobe(op);
577
578         return &op->kp;
579 }
580
581 static void __kprobes init_aggr_kprobe(struct kprobe *ap, struct kprobe *p);
582
583 /*
584  * Prepare an optimized_kprobe and optimize it
585  * NOTE: p must be a normal registered kprobe
586  */
587 static __kprobes void try_to_optimize_kprobe(struct kprobe *p)
588 {
589         struct kprobe *ap;
590         struct optimized_kprobe *op;
591
592         ap = alloc_aggr_kprobe(p);
593         if (!ap)
594                 return;
595
596         op = container_of(ap, struct optimized_kprobe, kp);
597         if (!arch_prepared_optinsn(&op->optinsn)) {
598                 /* If failed to setup optimizing, fallback to kprobe */
599                 free_aggr_kprobe(ap);
600                 return;
601         }
602
603         init_aggr_kprobe(ap, p);
604         optimize_kprobe(ap);
605 }
606
607 #ifdef CONFIG_SYSCTL
608 /* This should be called with kprobe_mutex locked */
609 static void __kprobes optimize_all_kprobes(void)
610 {
611         struct hlist_head *head;
612         struct hlist_node *node;
613         struct kprobe *p;
614         unsigned int i;
615
616         /* If optimization is already allowed, just return */
617         if (kprobes_allow_optimization)
618                 return;
619
620         kprobes_allow_optimization = true;
621         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
622                 head = &kprobe_table[i];
623                 hlist_for_each_entry_rcu(p, node, head, hlist)
624                         if (!kprobe_disabled(p))
625                                 optimize_kprobe(p);
626         }
627         printk(KERN_INFO "Kprobes globally optimized\n");
628 }
629
630 /* This should be called with kprobe_mutex locked */
631 static void __kprobes unoptimize_all_kprobes(void)
632 {
633         struct hlist_head *head;
634         struct hlist_node *node;
635         struct kprobe *p;
636         unsigned int i;
637
638         /* If optimization is already prohibited, just return */
639         if (!kprobes_allow_optimization)
640                 return;
641
642         kprobes_allow_optimization = false;
643         printk(KERN_INFO "Kprobes globally unoptimized\n");
644         get_online_cpus();      /* For avoiding text_mutex deadlock */
645         mutex_lock(&text_mutex);
646         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
647                 head = &kprobe_table[i];
648                 hlist_for_each_entry_rcu(p, node, head, hlist) {
649                         if (!kprobe_disabled(p))
650                                 unoptimize_kprobe(p);
651                 }
652         }
653
654         mutex_unlock(&text_mutex);
655         put_online_cpus();
656         /* Allow all currently running kprobes to complete */
657         synchronize_sched();
658 }
659
660 int sysctl_kprobes_optimization;
661 int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
662                                       void __user *buffer, size_t *length,
663                                       loff_t *ppos)
664 {
665         int ret;
666
667         mutex_lock(&kprobe_mutex);
668         sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0;
669         ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
670
671         if (sysctl_kprobes_optimization)
672                 optimize_all_kprobes();
673         else
674                 unoptimize_all_kprobes();
675         mutex_unlock(&kprobe_mutex);
676
677         return ret;
678 }
679 #endif /* CONFIG_SYSCTL */
680
681 static void __kprobes __arm_kprobe(struct kprobe *p)
682 {
683         struct kprobe *_p;
684
685         /* Check collision with other optimized kprobes */
686         _p = get_optimized_kprobe((unsigned long)p->addr);
687         if (unlikely(_p))
688                 unoptimize_kprobe(_p); /* Fallback to unoptimized kprobe */
689
690         arch_arm_kprobe(p);
691         optimize_kprobe(p);     /* Try to optimize (add kprobe to a list) */
692 }
693
694 static void __kprobes __disarm_kprobe(struct kprobe *p)
695 {
696         struct kprobe *_p;
697
698         unoptimize_kprobe(p);   /* Try to unoptimize */
699         arch_disarm_kprobe(p);
700
701         /* If another kprobe was blocked, optimize it. */
702         _p = get_optimized_kprobe((unsigned long)p->addr);
703         if (unlikely(_p))
704                 optimize_kprobe(_p);
705 }
706
707 #else /* !CONFIG_OPTPROBES */
708
709 #define optimize_kprobe(p)                      do {} while (0)
710 #define unoptimize_kprobe(p)                    do {} while (0)
711 #define kill_optimized_kprobe(p)                do {} while (0)
712 #define prepare_optimized_kprobe(p)             do {} while (0)
713 #define try_to_optimize_kprobe(p)               do {} while (0)
714 #define __arm_kprobe(p)                         arch_arm_kprobe(p)
715 #define __disarm_kprobe(p)                      arch_disarm_kprobe(p)
716
717 static __kprobes void free_aggr_kprobe(struct kprobe *p)
718 {
719         kfree(p);
720 }
721
722 static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
723 {
724         return kzalloc(sizeof(struct kprobe), GFP_KERNEL);
725 }
726 #endif /* CONFIG_OPTPROBES */
727
728 /* Arm a kprobe with text_mutex */
729 static void __kprobes arm_kprobe(struct kprobe *kp)
730 {
731         /*
732          * Here, since __arm_kprobe() doesn't use stop_machine(),
733          * this doesn't cause deadlock on text_mutex. So, we don't
734          * need get_online_cpus().
735          */
736         mutex_lock(&text_mutex);
737         __arm_kprobe(kp);
738         mutex_unlock(&text_mutex);
739 }
740
741 /* Disarm a kprobe with text_mutex */
742 static void __kprobes disarm_kprobe(struct kprobe *kp)
743 {
744         get_online_cpus();      /* For avoiding text_mutex deadlock */
745         mutex_lock(&text_mutex);
746         __disarm_kprobe(kp);
747         mutex_unlock(&text_mutex);
748         put_online_cpus();
749 }
750
751 /*
752  * Aggregate handlers for multiple kprobes support - these handlers
753  * take care of invoking the individual kprobe handlers on p->list
754  */
755 static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
756 {
757         struct kprobe *kp;
758
759         list_for_each_entry_rcu(kp, &p->list, list) {
760                 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
761                         set_kprobe_instance(kp);
762                         if (kp->pre_handler(kp, regs))
763                                 return 1;
764                 }
765                 reset_kprobe_instance();
766         }
767         return 0;
768 }
769
770 static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
771                                         unsigned long flags)
772 {
773         struct kprobe *kp;
774
775         list_for_each_entry_rcu(kp, &p->list, list) {
776                 if (kp->post_handler && likely(!kprobe_disabled(kp))) {
777                         set_kprobe_instance(kp);
778                         kp->post_handler(kp, regs, flags);
779                         reset_kprobe_instance();
780                 }
781         }
782 }
783
784 static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
785                                         int trapnr)
786 {
787         struct kprobe *cur = __get_cpu_var(kprobe_instance);
788
789         /*
790          * if we faulted "during" the execution of a user specified
791          * probe handler, invoke just that probe's fault handler
792          */
793         if (cur && cur->fault_handler) {
794                 if (cur->fault_handler(cur, regs, trapnr))
795                         return 1;
796         }
797         return 0;
798 }
799
800 static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
801 {
802         struct kprobe *cur = __get_cpu_var(kprobe_instance);
803         int ret = 0;
804
805         if (cur && cur->break_handler) {
806                 if (cur->break_handler(cur, regs))
807                         ret = 1;
808         }
809         reset_kprobe_instance();
810         return ret;
811 }
812
813 /* Walks the list and increments nmissed count for multiprobe case */
814 void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
815 {
816         struct kprobe *kp;
817         if (!kprobe_aggrprobe(p)) {
818                 p->nmissed++;
819         } else {
820                 list_for_each_entry_rcu(kp, &p->list, list)
821                         kp->nmissed++;
822         }
823         return;
824 }
825
826 void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
827                                 struct hlist_head *head)
828 {
829         struct kretprobe *rp = ri->rp;
830
831         /* remove rp inst off the rprobe_inst_table */
832         hlist_del(&ri->hlist);
833         INIT_HLIST_NODE(&ri->hlist);
834         if (likely(rp)) {
835                 spin_lock(&rp->lock);
836                 hlist_add_head(&ri->hlist, &rp->free_instances);
837                 spin_unlock(&rp->lock);
838         } else
839                 /* Unregistering */
840                 hlist_add_head(&ri->hlist, head);
841 }
842
843 void __kprobes kretprobe_hash_lock(struct task_struct *tsk,
844                          struct hlist_head **head, unsigned long *flags)
845 __acquires(hlist_lock)
846 {
847         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
848         spinlock_t *hlist_lock;
849
850         *head = &kretprobe_inst_table[hash];
851         hlist_lock = kretprobe_table_lock_ptr(hash);
852         spin_lock_irqsave(hlist_lock, *flags);
853 }
854
855 static void __kprobes kretprobe_table_lock(unsigned long hash,
856         unsigned long *flags)
857 __acquires(hlist_lock)
858 {
859         spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
860         spin_lock_irqsave(hlist_lock, *flags);
861 }
862
863 void __kprobes kretprobe_hash_unlock(struct task_struct *tsk,
864         unsigned long *flags)
865 __releases(hlist_lock)
866 {
867         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
868         spinlock_t *hlist_lock;
869
870         hlist_lock = kretprobe_table_lock_ptr(hash);
871         spin_unlock_irqrestore(hlist_lock, *flags);
872 }
873
874 static void __kprobes kretprobe_table_unlock(unsigned long hash,
875        unsigned long *flags)
876 __releases(hlist_lock)
877 {
878         spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
879         spin_unlock_irqrestore(hlist_lock, *flags);
880 }
881
882 /*
883  * This function is called from finish_task_switch when task tk becomes dead,
884  * so that we can recycle any function-return probe instances associated
885  * with this task. These left over instances represent probed functions
886  * that have been called but will never return.
887  */
888 void __kprobes kprobe_flush_task(struct task_struct *tk)
889 {
890         struct kretprobe_instance *ri;
891         struct hlist_head *head, empty_rp;
892         struct hlist_node *node, *tmp;
893         unsigned long hash, flags = 0;
894
895         if (unlikely(!kprobes_initialized))
896                 /* Early boot.  kretprobe_table_locks not yet initialized. */
897                 return;
898
899         hash = hash_ptr(tk, KPROBE_HASH_BITS);
900         head = &kretprobe_inst_table[hash];
901         kretprobe_table_lock(hash, &flags);
902         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
903                 if (ri->task == tk)
904                         recycle_rp_inst(ri, &empty_rp);
905         }
906         kretprobe_table_unlock(hash, &flags);
907         INIT_HLIST_HEAD(&empty_rp);
908         hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
909                 hlist_del(&ri->hlist);
910                 kfree(ri);
911         }
912 }
913
914 static inline void free_rp_inst(struct kretprobe *rp)
915 {
916         struct kretprobe_instance *ri;
917         struct hlist_node *pos, *next;
918
919         hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, hlist) {
920                 hlist_del(&ri->hlist);
921                 kfree(ri);
922         }
923 }
924
925 static void __kprobes cleanup_rp_inst(struct kretprobe *rp)
926 {
927         unsigned long flags, hash;
928         struct kretprobe_instance *ri;
929         struct hlist_node *pos, *next;
930         struct hlist_head *head;
931
932         /* No race here */
933         for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
934                 kretprobe_table_lock(hash, &flags);
935                 head = &kretprobe_inst_table[hash];
936                 hlist_for_each_entry_safe(ri, pos, next, head, hlist) {
937                         if (ri->rp == rp)
938                                 ri->rp = NULL;
939                 }
940                 kretprobe_table_unlock(hash, &flags);
941         }
942         free_rp_inst(rp);
943 }
944
945 /*
946 * Add the new probe to ap->list. Fail if this is the
947 * second jprobe at the address - two jprobes can't coexist
948 */
949 static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p)
950 {
951         BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
952
953         if (p->break_handler || p->post_handler)
954                 unoptimize_kprobe(ap);  /* Fall back to normal kprobe */
955
956         if (p->break_handler) {
957                 if (ap->break_handler)
958                         return -EEXIST;
959                 list_add_tail_rcu(&p->list, &ap->list);
960                 ap->break_handler = aggr_break_handler;
961         } else
962                 list_add_rcu(&p->list, &ap->list);
963         if (p->post_handler && !ap->post_handler)
964                 ap->post_handler = aggr_post_handler;
965
966         if (kprobe_disabled(ap) && !kprobe_disabled(p)) {
967                 ap->flags &= ~KPROBE_FLAG_DISABLED;
968                 if (!kprobes_all_disarmed)
969                         /* Arm the breakpoint again. */
970                         __arm_kprobe(ap);
971         }
972         return 0;
973 }
974
975 /*
976  * Fill in the required fields of the "manager kprobe". Replace the
977  * earlier kprobe in the hlist with the manager kprobe
978  */
979 static void __kprobes init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
980 {
981         /* Copy p's insn slot to ap */
982         copy_kprobe(p, ap);
983         flush_insn_slot(ap);
984         ap->addr = p->addr;
985         ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED;
986         ap->pre_handler = aggr_pre_handler;
987         ap->fault_handler = aggr_fault_handler;
988         /* We don't care the kprobe which has gone. */
989         if (p->post_handler && !kprobe_gone(p))
990                 ap->post_handler = aggr_post_handler;
991         if (p->break_handler && !kprobe_gone(p))
992                 ap->break_handler = aggr_break_handler;
993
994         INIT_LIST_HEAD(&ap->list);
995         INIT_HLIST_NODE(&ap->hlist);
996
997         list_add_rcu(&p->list, &ap->list);
998         hlist_replace_rcu(&p->hlist, &ap->hlist);
999 }
1000
1001 /*
1002  * This is the second or subsequent kprobe at the address - handle
1003  * the intricacies
1004  */
1005 static int __kprobes register_aggr_kprobe(struct kprobe *orig_p,
1006                                           struct kprobe *p)
1007 {
1008         int ret = 0;
1009         struct kprobe *ap = orig_p;
1010
1011         if (!kprobe_aggrprobe(orig_p)) {
1012                 /* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */
1013                 ap = alloc_aggr_kprobe(orig_p);
1014                 if (!ap)
1015                         return -ENOMEM;
1016                 init_aggr_kprobe(ap, orig_p);
1017         }
1018
1019         if (kprobe_gone(ap)) {
1020                 /*
1021                  * Attempting to insert new probe at the same location that
1022                  * had a probe in the module vaddr area which already
1023                  * freed. So, the instruction slot has already been
1024                  * released. We need a new slot for the new probe.
1025                  */
1026                 ret = arch_prepare_kprobe(ap);
1027                 if (ret)
1028                         /*
1029                          * Even if fail to allocate new slot, don't need to
1030                          * free aggr_probe. It will be used next time, or
1031                          * freed by unregister_kprobe.
1032                          */
1033                         return ret;
1034
1035                 /* Prepare optimized instructions if possible. */
1036                 prepare_optimized_kprobe(ap);
1037
1038                 /*
1039                  * Clear gone flag to prevent allocating new slot again, and
1040                  * set disabled flag because it is not armed yet.
1041                  */
1042                 ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
1043                             | KPROBE_FLAG_DISABLED;
1044         }
1045
1046         /* Copy ap's insn slot to p */
1047         copy_kprobe(ap, p);
1048         return add_new_kprobe(ap, p);
1049 }
1050
1051 static int __kprobes in_kprobes_functions(unsigned long addr)
1052 {
1053         struct kprobe_blackpoint *kb;
1054
1055         if (addr >= (unsigned long)__kprobes_text_start &&
1056             addr < (unsigned long)__kprobes_text_end)
1057                 return -EINVAL;
1058         /*
1059          * If there exists a kprobe_blacklist, verify and
1060          * fail any probe registration in the prohibited area
1061          */
1062         for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
1063                 if (kb->start_addr) {
1064                         if (addr >= kb->start_addr &&
1065                             addr < (kb->start_addr + kb->range))
1066                                 return -EINVAL;
1067                 }
1068         }
1069         return 0;
1070 }
1071
1072 /*
1073  * If we have a symbol_name argument, look it up and add the offset field
1074  * to it. This way, we can specify a relative address to a symbol.
1075  */
1076 static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p)
1077 {
1078         kprobe_opcode_t *addr = p->addr;
1079         if (p->symbol_name) {
1080                 if (addr)
1081                         return NULL;
1082                 kprobe_lookup_name(p->symbol_name, addr);
1083         }
1084
1085         if (!addr)
1086                 return NULL;
1087         return (kprobe_opcode_t *)(((char *)addr) + p->offset);
1088 }
1089
1090 /* Check passed kprobe is valid and return kprobe in kprobe_table. */
1091 static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p)
1092 {
1093         struct kprobe *ap, *list_p;
1094
1095         ap = get_kprobe(p->addr);
1096         if (unlikely(!ap))
1097                 return NULL;
1098
1099         if (p != ap) {
1100                 list_for_each_entry_rcu(list_p, &ap->list, list)
1101                         if (list_p == p)
1102                         /* kprobe p is a valid probe */
1103                                 goto valid;
1104                 return NULL;
1105         }
1106 valid:
1107         return ap;
1108 }
1109
1110 /* Return error if the kprobe is being re-registered */
1111 static inline int check_kprobe_rereg(struct kprobe *p)
1112 {
1113         int ret = 0;
1114
1115         mutex_lock(&kprobe_mutex);
1116         if (__get_valid_kprobe(p))
1117                 ret = -EINVAL;
1118         mutex_unlock(&kprobe_mutex);
1119
1120         return ret;
1121 }
1122
1123 int __kprobes register_kprobe(struct kprobe *p)
1124 {
1125         int ret = 0;
1126         struct kprobe *old_p;
1127         struct module *probed_mod;
1128         kprobe_opcode_t *addr;
1129
1130         addr = kprobe_addr(p);
1131         if (!addr)
1132                 return -EINVAL;
1133         p->addr = addr;
1134
1135         ret = check_kprobe_rereg(p);
1136         if (ret)
1137                 return ret;
1138
1139         jump_label_lock();
1140         preempt_disable();
1141         if (!kernel_text_address((unsigned long) p->addr) ||
1142             in_kprobes_functions((unsigned long) p->addr) ||
1143             ftrace_text_reserved(p->addr, p->addr) ||
1144             jump_label_text_reserved(p->addr, p->addr))
1145                 goto fail_with_jump_label;
1146
1147         /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
1148         p->flags &= KPROBE_FLAG_DISABLED;
1149
1150         /*
1151          * Check if are we probing a module.
1152          */
1153         probed_mod = __module_text_address((unsigned long) p->addr);
1154         if (probed_mod) {
1155                 /*
1156                  * We must hold a refcount of the probed module while updating
1157                  * its code to prohibit unexpected unloading.
1158                  */
1159                 if (unlikely(!try_module_get(probed_mod)))
1160                         goto fail_with_jump_label;
1161
1162                 /*
1163                  * If the module freed .init.text, we couldn't insert
1164                  * kprobes in there.
1165                  */
1166                 if (within_module_init((unsigned long)p->addr, probed_mod) &&
1167                     probed_mod->state != MODULE_STATE_COMING) {
1168                         module_put(probed_mod);
1169                         goto fail_with_jump_label;
1170                 }
1171         }
1172         preempt_enable();
1173         jump_label_unlock();
1174
1175         p->nmissed = 0;
1176         INIT_LIST_HEAD(&p->list);
1177         mutex_lock(&kprobe_mutex);
1178
1179         jump_label_lock(); /* needed to call jump_label_text_reserved() */
1180
1181         get_online_cpus();      /* For avoiding text_mutex deadlock. */
1182         mutex_lock(&text_mutex);
1183
1184         old_p = get_kprobe(p->addr);
1185         if (old_p) {
1186                 /* Since this may unoptimize old_p, locking text_mutex. */
1187                 ret = register_aggr_kprobe(old_p, p);
1188                 goto out;
1189         }
1190
1191         ret = arch_prepare_kprobe(p);
1192         if (ret)
1193                 goto out;
1194
1195         INIT_HLIST_NODE(&p->hlist);
1196         hlist_add_head_rcu(&p->hlist,
1197                        &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
1198
1199         if (!kprobes_all_disarmed && !kprobe_disabled(p))
1200                 __arm_kprobe(p);
1201
1202         /* Try to optimize kprobe */
1203         try_to_optimize_kprobe(p);
1204
1205 out:
1206         mutex_unlock(&text_mutex);
1207         put_online_cpus();
1208         jump_label_unlock();
1209         mutex_unlock(&kprobe_mutex);
1210
1211         if (probed_mod)
1212                 module_put(probed_mod);
1213
1214         return ret;
1215
1216 fail_with_jump_label:
1217         preempt_enable();
1218         jump_label_unlock();
1219         return -EINVAL;
1220 }
1221 EXPORT_SYMBOL_GPL(register_kprobe);
1222
1223 /* Check if all probes on the aggrprobe are disabled */
1224 static int __kprobes aggr_kprobe_disabled(struct kprobe *ap)
1225 {
1226         struct kprobe *kp;
1227
1228         list_for_each_entry_rcu(kp, &ap->list, list)
1229                 if (!kprobe_disabled(kp))
1230                         /*
1231                          * There is an active probe on the list.
1232                          * We can't disable this ap.
1233                          */
1234                         return 0;
1235
1236         return 1;
1237 }
1238
1239 /* Disable one kprobe: Make sure called under kprobe_mutex is locked */
1240 static struct kprobe *__kprobes __disable_kprobe(struct kprobe *p)
1241 {
1242         struct kprobe *orig_p;
1243
1244         /* Get an original kprobe for return */
1245         orig_p = __get_valid_kprobe(p);
1246         if (unlikely(orig_p == NULL))
1247                 return NULL;
1248
1249         if (!kprobe_disabled(p)) {
1250                 /* Disable probe if it is a child probe */
1251                 if (p != orig_p)
1252                         p->flags |= KPROBE_FLAG_DISABLED;
1253
1254                 /* Try to disarm and disable this/parent probe */
1255                 if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
1256                         disarm_kprobe(orig_p);
1257                         orig_p->flags |= KPROBE_FLAG_DISABLED;
1258                 }
1259         }
1260
1261         return orig_p;
1262 }
1263
1264 /*
1265  * Unregister a kprobe without a scheduler synchronization.
1266  */
1267 static int __kprobes __unregister_kprobe_top(struct kprobe *p)
1268 {
1269         struct kprobe *ap, *list_p;
1270
1271         /* Disable kprobe. This will disarm it if needed. */
1272         ap = __disable_kprobe(p);
1273         if (ap == NULL)
1274                 return -EINVAL;
1275
1276         if (ap == p)
1277                 /*
1278                  * This probe is an independent(and non-optimized) kprobe
1279                  * (not an aggrprobe). Remove from the hash list.
1280                  */
1281                 goto disarmed;
1282
1283         /* Following process expects this probe is an aggrprobe */
1284         WARN_ON(!kprobe_aggrprobe(ap));
1285
1286         if (list_is_singular(&ap->list))
1287                 /* This probe is the last child of aggrprobe */
1288                 goto disarmed;
1289         else {
1290                 /* If disabling probe has special handlers, update aggrprobe */
1291                 if (p->break_handler && !kprobe_gone(p))
1292                         ap->break_handler = NULL;
1293                 if (p->post_handler && !kprobe_gone(p)) {
1294                         list_for_each_entry_rcu(list_p, &ap->list, list) {
1295                                 if ((list_p != p) && (list_p->post_handler))
1296                                         goto noclean;
1297                         }
1298                         ap->post_handler = NULL;
1299                 }
1300 noclean:
1301                 /*
1302                  * Remove from the aggrprobe: this path will do nothing in
1303                  * __unregister_kprobe_bottom().
1304                  */
1305                 list_del_rcu(&p->list);
1306                 if (!kprobe_disabled(ap) && !kprobes_all_disarmed)
1307                         /*
1308                          * Try to optimize this probe again, because post
1309                          * handler may have been changed.
1310                          */
1311                         optimize_kprobe(ap);
1312         }
1313         return 0;
1314
1315 disarmed:
1316         hlist_del_rcu(&ap->hlist);
1317         return 0;
1318 }
1319
1320 static void __kprobes __unregister_kprobe_bottom(struct kprobe *p)
1321 {
1322         struct kprobe *ap;
1323
1324         if (list_empty(&p->list))
1325                 arch_remove_kprobe(p);
1326         else if (list_is_singular(&p->list)) {
1327                 /* "p" is the last child of an aggr_kprobe */
1328                 ap = list_entry(p->list.next, struct kprobe, list);
1329                 list_del(&p->list);
1330                 arch_remove_kprobe(ap);
1331                 free_aggr_kprobe(ap);
1332         }
1333 }
1334
1335 int __kprobes register_kprobes(struct kprobe **kps, int num)
1336 {
1337         int i, ret = 0;
1338
1339         if (num <= 0)
1340                 return -EINVAL;
1341         for (i = 0; i < num; i++) {
1342                 ret = register_kprobe(kps[i]);
1343                 if (ret < 0) {
1344                         if (i > 0)
1345                                 unregister_kprobes(kps, i);
1346                         break;
1347                 }
1348         }
1349         return ret;
1350 }
1351 EXPORT_SYMBOL_GPL(register_kprobes);
1352
1353 void __kprobes unregister_kprobe(struct kprobe *p)
1354 {
1355         unregister_kprobes(&p, 1);
1356 }
1357 EXPORT_SYMBOL_GPL(unregister_kprobe);
1358
1359 void __kprobes unregister_kprobes(struct kprobe **kps, int num)
1360 {
1361         int i;
1362
1363         if (num <= 0)
1364                 return;
1365         mutex_lock(&kprobe_mutex);
1366         for (i = 0; i < num; i++)
1367                 if (__unregister_kprobe_top(kps[i]) < 0)
1368                         kps[i]->addr = NULL;
1369         mutex_unlock(&kprobe_mutex);
1370
1371         synchronize_sched();
1372         for (i = 0; i < num; i++)
1373                 if (kps[i]->addr)
1374                         __unregister_kprobe_bottom(kps[i]);
1375 }
1376 EXPORT_SYMBOL_GPL(unregister_kprobes);
1377
1378 static struct notifier_block kprobe_exceptions_nb = {
1379         .notifier_call = kprobe_exceptions_notify,
1380         .priority = 0x7fffffff /* we need to be notified first */
1381 };
1382
1383 unsigned long __weak arch_deref_entry_point(void *entry)
1384 {
1385         return (unsigned long)entry;
1386 }
1387
1388 int __kprobes register_jprobes(struct jprobe **jps, int num)
1389 {
1390         struct jprobe *jp;
1391         int ret = 0, i;
1392
1393         if (num <= 0)
1394                 return -EINVAL;
1395         for (i = 0; i < num; i++) {
1396                 unsigned long addr, offset;
1397                 jp = jps[i];
1398                 addr = arch_deref_entry_point(jp->entry);
1399
1400                 /* Verify probepoint is a function entry point */
1401                 if (kallsyms_lookup_size_offset(addr, NULL, &offset) &&
1402                     offset == 0) {
1403                         jp->kp.pre_handler = setjmp_pre_handler;
1404                         jp->kp.break_handler = longjmp_break_handler;
1405                         ret = register_kprobe(&jp->kp);
1406                 } else
1407                         ret = -EINVAL;
1408
1409                 if (ret < 0) {
1410                         if (i > 0)
1411                                 unregister_jprobes(jps, i);
1412                         break;
1413                 }
1414         }
1415         return ret;
1416 }
1417 EXPORT_SYMBOL_GPL(register_jprobes);
1418
1419 int __kprobes register_jprobe(struct jprobe *jp)
1420 {
1421         return register_jprobes(&jp, 1);
1422 }
1423 EXPORT_SYMBOL_GPL(register_jprobe);
1424
1425 void __kprobes unregister_jprobe(struct jprobe *jp)
1426 {
1427         unregister_jprobes(&jp, 1);
1428 }
1429 EXPORT_SYMBOL_GPL(unregister_jprobe);
1430
1431 void __kprobes unregister_jprobes(struct jprobe **jps, int num)
1432 {
1433         int i;
1434
1435         if (num <= 0)
1436                 return;
1437         mutex_lock(&kprobe_mutex);
1438         for (i = 0; i < num; i++)
1439                 if (__unregister_kprobe_top(&jps[i]->kp) < 0)
1440                         jps[i]->kp.addr = NULL;
1441         mutex_unlock(&kprobe_mutex);
1442
1443         synchronize_sched();
1444         for (i = 0; i < num; i++) {
1445                 if (jps[i]->kp.addr)
1446                         __unregister_kprobe_bottom(&jps[i]->kp);
1447         }
1448 }
1449 EXPORT_SYMBOL_GPL(unregister_jprobes);
1450
1451 #ifdef CONFIG_KRETPROBES
1452 /*
1453  * This kprobe pre_handler is registered with every kretprobe. When probe
1454  * hits it will set up the return probe.
1455  */
1456 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
1457                                            struct pt_regs *regs)
1458 {
1459         struct kretprobe *rp = container_of(p, struct kretprobe, kp);
1460         unsigned long hash, flags = 0;
1461         struct kretprobe_instance *ri;
1462
1463         /*TODO: consider to only swap the RA after the last pre_handler fired */
1464         hash = hash_ptr(current, KPROBE_HASH_BITS);
1465         spin_lock_irqsave(&rp->lock, flags);
1466         if (!hlist_empty(&rp->free_instances)) {
1467                 ri = hlist_entry(rp->free_instances.first,
1468                                 struct kretprobe_instance, hlist);
1469                 hlist_del(&ri->hlist);
1470                 spin_unlock_irqrestore(&rp->lock, flags);
1471
1472                 ri->rp = rp;
1473                 ri->task = current;
1474
1475                 if (rp->entry_handler && rp->entry_handler(ri, regs))
1476                         return 0;
1477
1478                 arch_prepare_kretprobe(ri, regs);
1479
1480                 /* XXX(hch): why is there no hlist_move_head? */
1481                 INIT_HLIST_NODE(&ri->hlist);
1482                 kretprobe_table_lock(hash, &flags);
1483                 hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
1484                 kretprobe_table_unlock(hash, &flags);
1485         } else {
1486                 rp->nmissed++;
1487                 spin_unlock_irqrestore(&rp->lock, flags);
1488         }
1489         return 0;
1490 }
1491
1492 int __kprobes register_kretprobe(struct kretprobe *rp)
1493 {
1494         int ret = 0;
1495         struct kretprobe_instance *inst;
1496         int i;
1497         void *addr;
1498
1499         if (kretprobe_blacklist_size) {
1500                 addr = kprobe_addr(&rp->kp);
1501                 if (!addr)
1502                         return -EINVAL;
1503
1504                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1505                         if (kretprobe_blacklist[i].addr == addr)
1506                                 return -EINVAL;
1507                 }
1508         }
1509
1510         rp->kp.pre_handler = pre_handler_kretprobe;
1511         rp->kp.post_handler = NULL;
1512         rp->kp.fault_handler = NULL;
1513         rp->kp.break_handler = NULL;
1514
1515         /* Pre-allocate memory for max kretprobe instances */
1516         if (rp->maxactive <= 0) {
1517 #ifdef CONFIG_PREEMPT
1518                 rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
1519 #else
1520                 rp->maxactive = num_possible_cpus();
1521 #endif
1522         }
1523         spin_lock_init(&rp->lock);
1524         INIT_HLIST_HEAD(&rp->free_instances);
1525         for (i = 0; i < rp->maxactive; i++) {
1526                 inst = kmalloc(sizeof(struct kretprobe_instance) +
1527                                rp->data_size, GFP_KERNEL);
1528                 if (inst == NULL) {
1529                         free_rp_inst(rp);
1530                         return -ENOMEM;
1531                 }
1532                 INIT_HLIST_NODE(&inst->hlist);
1533                 hlist_add_head(&inst->hlist, &rp->free_instances);
1534         }
1535
1536         rp->nmissed = 0;
1537         /* Establish function entry probe point */
1538         ret = register_kprobe(&rp->kp);
1539         if (ret != 0)
1540                 free_rp_inst(rp);
1541         return ret;
1542 }
1543 EXPORT_SYMBOL_GPL(register_kretprobe);
1544
1545 int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1546 {
1547         int ret = 0, i;
1548
1549         if (num <= 0)
1550                 return -EINVAL;
1551         for (i = 0; i < num; i++) {
1552                 ret = register_kretprobe(rps[i]);
1553                 if (ret < 0) {
1554                         if (i > 0)
1555                                 unregister_kretprobes(rps, i);
1556                         break;
1557                 }
1558         }
1559         return ret;
1560 }
1561 EXPORT_SYMBOL_GPL(register_kretprobes);
1562
1563 void __kprobes unregister_kretprobe(struct kretprobe *rp)
1564 {
1565         unregister_kretprobes(&rp, 1);
1566 }
1567 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1568
1569 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1570 {
1571         int i;
1572
1573         if (num <= 0)
1574                 return;
1575         mutex_lock(&kprobe_mutex);
1576         for (i = 0; i < num; i++)
1577                 if (__unregister_kprobe_top(&rps[i]->kp) < 0)
1578                         rps[i]->kp.addr = NULL;
1579         mutex_unlock(&kprobe_mutex);
1580
1581         synchronize_sched();
1582         for (i = 0; i < num; i++) {
1583                 if (rps[i]->kp.addr) {
1584                         __unregister_kprobe_bottom(&rps[i]->kp);
1585                         cleanup_rp_inst(rps[i]);
1586                 }
1587         }
1588 }
1589 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1590
1591 #else /* CONFIG_KRETPROBES */
1592 int __kprobes register_kretprobe(struct kretprobe *rp)
1593 {
1594         return -ENOSYS;
1595 }
1596 EXPORT_SYMBOL_GPL(register_kretprobe);
1597
1598 int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1599 {
1600         return -ENOSYS;
1601 }
1602 EXPORT_SYMBOL_GPL(register_kretprobes);
1603
1604 void __kprobes unregister_kretprobe(struct kretprobe *rp)
1605 {
1606 }
1607 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1608
1609 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1610 {
1611 }
1612 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1613
1614 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
1615                                            struct pt_regs *regs)
1616 {
1617         return 0;
1618 }
1619
1620 #endif /* CONFIG_KRETPROBES */
1621
1622 /* Set the kprobe gone and remove its instruction buffer. */
1623 static void __kprobes kill_kprobe(struct kprobe *p)
1624 {
1625         struct kprobe *kp;
1626
1627         p->flags |= KPROBE_FLAG_GONE;
1628         if (kprobe_aggrprobe(p)) {
1629                 /*
1630                  * If this is an aggr_kprobe, we have to list all the
1631                  * chained probes and mark them GONE.
1632                  */
1633                 list_for_each_entry_rcu(kp, &p->list, list)
1634                         kp->flags |= KPROBE_FLAG_GONE;
1635                 p->post_handler = NULL;
1636                 p->break_handler = NULL;
1637                 kill_optimized_kprobe(p);
1638         }
1639         /*
1640          * Here, we can remove insn_slot safely, because no thread calls
1641          * the original probed function (which will be freed soon) any more.
1642          */
1643         arch_remove_kprobe(p);
1644 }
1645
1646 /* Disable one kprobe */
1647 int __kprobes disable_kprobe(struct kprobe *kp)
1648 {
1649         int ret = 0;
1650
1651         mutex_lock(&kprobe_mutex);
1652
1653         /* Disable this kprobe */
1654         if (__disable_kprobe(kp) == NULL)
1655                 ret = -EINVAL;
1656
1657         mutex_unlock(&kprobe_mutex);
1658         return ret;
1659 }
1660 EXPORT_SYMBOL_GPL(disable_kprobe);
1661
1662 /* Enable one kprobe */
1663 int __kprobes enable_kprobe(struct kprobe *kp)
1664 {
1665         int ret = 0;
1666         struct kprobe *p;
1667
1668         mutex_lock(&kprobe_mutex);
1669
1670         /* Check whether specified probe is valid. */
1671         p = __get_valid_kprobe(kp);
1672         if (unlikely(p == NULL)) {
1673                 ret = -EINVAL;
1674                 goto out;
1675         }
1676
1677         if (kprobe_gone(kp)) {
1678                 /* This kprobe has gone, we couldn't enable it. */
1679                 ret = -EINVAL;
1680                 goto out;
1681         }
1682
1683         if (p != kp)
1684                 kp->flags &= ~KPROBE_FLAG_DISABLED;
1685
1686         if (!kprobes_all_disarmed && kprobe_disabled(p)) {
1687                 p->flags &= ~KPROBE_FLAG_DISABLED;
1688                 arm_kprobe(p);
1689         }
1690 out:
1691         mutex_unlock(&kprobe_mutex);
1692         return ret;
1693 }
1694 EXPORT_SYMBOL_GPL(enable_kprobe);
1695
1696 void __kprobes dump_kprobe(struct kprobe *kp)
1697 {
1698         printk(KERN_WARNING "Dumping kprobe:\n");
1699         printk(KERN_WARNING "Name: %s\nAddress: %p\nOffset: %x\n",
1700                kp->symbol_name, kp->addr, kp->offset);
1701 }
1702
1703 /* Module notifier call back, checking kprobes on the module */
1704 static int __kprobes kprobes_module_callback(struct notifier_block *nb,
1705                                              unsigned long val, void *data)
1706 {
1707         struct module *mod = data;
1708         struct hlist_head *head;
1709         struct hlist_node *node;
1710         struct kprobe *p;
1711         unsigned int i;
1712         int checkcore = (val == MODULE_STATE_GOING);
1713
1714         if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
1715                 return NOTIFY_DONE;
1716
1717         /*
1718          * When MODULE_STATE_GOING was notified, both of module .text and
1719          * .init.text sections would be freed. When MODULE_STATE_LIVE was
1720          * notified, only .init.text section would be freed. We need to
1721          * disable kprobes which have been inserted in the sections.
1722          */
1723         mutex_lock(&kprobe_mutex);
1724         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1725                 head = &kprobe_table[i];
1726                 hlist_for_each_entry_rcu(p, node, head, hlist)
1727                         if (within_module_init((unsigned long)p->addr, mod) ||
1728                             (checkcore &&
1729                              within_module_core((unsigned long)p->addr, mod))) {
1730                                 /*
1731                                  * The vaddr this probe is installed will soon
1732                                  * be vfreed buy not synced to disk. Hence,
1733                                  * disarming the breakpoint isn't needed.
1734                                  */
1735                                 kill_kprobe(p);
1736                         }
1737         }
1738         mutex_unlock(&kprobe_mutex);
1739         return NOTIFY_DONE;
1740 }
1741
1742 static struct notifier_block kprobe_module_nb = {
1743         .notifier_call = kprobes_module_callback,
1744         .priority = 0
1745 };
1746
1747 static int __init init_kprobes(void)
1748 {
1749         int i, err = 0;
1750         unsigned long offset = 0, size = 0;
1751         char *modname, namebuf[128];
1752         const char *symbol_name;
1753         void *addr;
1754         struct kprobe_blackpoint *kb;
1755
1756         /* FIXME allocate the probe table, currently defined statically */
1757         /* initialize all list heads */
1758         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1759                 INIT_HLIST_HEAD(&kprobe_table[i]);
1760                 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
1761                 spin_lock_init(&(kretprobe_table_locks[i].lock));
1762         }
1763
1764         /*
1765          * Lookup and populate the kprobe_blacklist.
1766          *
1767          * Unlike the kretprobe blacklist, we'll need to determine
1768          * the range of addresses that belong to the said functions,
1769          * since a kprobe need not necessarily be at the beginning
1770          * of a function.
1771          */
1772         for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
1773                 kprobe_lookup_name(kb->name, addr);
1774                 if (!addr)
1775                         continue;
1776
1777                 kb->start_addr = (unsigned long)addr;
1778                 symbol_name = kallsyms_lookup(kb->start_addr,
1779                                 &size, &offset, &modname, namebuf);
1780                 if (!symbol_name)
1781                         kb->range = 0;
1782                 else
1783                         kb->range = size;
1784         }
1785
1786         if (kretprobe_blacklist_size) {
1787                 /* lookup the function address from its name */
1788                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1789                         kprobe_lookup_name(kretprobe_blacklist[i].name,
1790                                            kretprobe_blacklist[i].addr);
1791                         if (!kretprobe_blacklist[i].addr)
1792                                 printk("kretprobe: lookup failed: %s\n",
1793                                        kretprobe_blacklist[i].name);
1794                 }
1795         }
1796
1797 #if defined(CONFIG_OPTPROBES)
1798 #if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
1799         /* Init kprobe_optinsn_slots */
1800         kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
1801 #endif
1802         /* By default, kprobes can be optimized */
1803         kprobes_allow_optimization = true;
1804 #endif
1805
1806         /* By default, kprobes are armed */
1807         kprobes_all_disarmed = false;
1808
1809         err = arch_init_kprobes();
1810         if (!err)
1811                 err = register_die_notifier(&kprobe_exceptions_nb);
1812         if (!err)
1813                 err = register_module_notifier(&kprobe_module_nb);
1814
1815         kprobes_initialized = (err == 0);
1816
1817         if (!err)
1818                 init_test_probes();
1819         return err;
1820 }
1821
1822 #ifdef CONFIG_DEBUG_FS
1823 static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
1824                 const char *sym, int offset, char *modname, struct kprobe *pp)
1825 {
1826         char *kprobe_type;
1827
1828         if (p->pre_handler == pre_handler_kretprobe)
1829                 kprobe_type = "r";
1830         else if (p->pre_handler == setjmp_pre_handler)
1831                 kprobe_type = "j";
1832         else
1833                 kprobe_type = "k";
1834
1835         if (sym)
1836                 seq_printf(pi, "%p  %s  %s+0x%x  %s ",
1837                         p->addr, kprobe_type, sym, offset,
1838                         (modname ? modname : " "));
1839         else
1840                 seq_printf(pi, "%p  %s  %p ",
1841                         p->addr, kprobe_type, p->addr);
1842
1843         if (!pp)
1844                 pp = p;
1845         seq_printf(pi, "%s%s%s\n",
1846                 (kprobe_gone(p) ? "[GONE]" : ""),
1847                 ((kprobe_disabled(p) && !kprobe_gone(p)) ?  "[DISABLED]" : ""),
1848                 (kprobe_optimized(pp) ? "[OPTIMIZED]" : ""));
1849 }
1850
1851 static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
1852 {
1853         return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
1854 }
1855
1856 static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
1857 {
1858         (*pos)++;
1859         if (*pos >= KPROBE_TABLE_SIZE)
1860                 return NULL;
1861         return pos;
1862 }
1863
1864 static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v)
1865 {
1866         /* Nothing to do */
1867 }
1868
1869 static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v)
1870 {
1871         struct hlist_head *head;
1872         struct hlist_node *node;
1873         struct kprobe *p, *kp;
1874         const char *sym = NULL;
1875         unsigned int i = *(loff_t *) v;
1876         unsigned long offset = 0;
1877         char *modname, namebuf[128];
1878
1879         head = &kprobe_table[i];
1880         preempt_disable();
1881         hlist_for_each_entry_rcu(p, node, head, hlist) {
1882                 sym = kallsyms_lookup((unsigned long)p->addr, NULL,
1883                                         &offset, &modname, namebuf);
1884                 if (kprobe_aggrprobe(p)) {
1885                         list_for_each_entry_rcu(kp, &p->list, list)
1886                                 report_probe(pi, kp, sym, offset, modname, p);
1887                 } else
1888                         report_probe(pi, p, sym, offset, modname, NULL);
1889         }
1890         preempt_enable();
1891         return 0;
1892 }
1893
1894 static const struct seq_operations kprobes_seq_ops = {
1895         .start = kprobe_seq_start,
1896         .next  = kprobe_seq_next,
1897         .stop  = kprobe_seq_stop,
1898         .show  = show_kprobe_addr
1899 };
1900
1901 static int __kprobes kprobes_open(struct inode *inode, struct file *filp)
1902 {
1903         return seq_open(filp, &kprobes_seq_ops);
1904 }
1905
1906 static const struct file_operations debugfs_kprobes_operations = {
1907         .open           = kprobes_open,
1908         .read           = seq_read,
1909         .llseek         = seq_lseek,
1910         .release        = seq_release,
1911 };
1912
1913 static void __kprobes arm_all_kprobes(void)
1914 {
1915         struct hlist_head *head;
1916         struct hlist_node *node;
1917         struct kprobe *p;
1918         unsigned int i;
1919
1920         mutex_lock(&kprobe_mutex);
1921
1922         /* If kprobes are armed, just return */
1923         if (!kprobes_all_disarmed)
1924                 goto already_enabled;
1925
1926         /* Arming kprobes doesn't optimize kprobe itself */
1927         mutex_lock(&text_mutex);
1928         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1929                 head = &kprobe_table[i];
1930                 hlist_for_each_entry_rcu(p, node, head, hlist)
1931                         if (!kprobe_disabled(p))
1932                                 __arm_kprobe(p);
1933         }
1934         mutex_unlock(&text_mutex);
1935
1936         kprobes_all_disarmed = false;
1937         printk(KERN_INFO "Kprobes globally enabled\n");
1938
1939 already_enabled:
1940         mutex_unlock(&kprobe_mutex);
1941         return;
1942 }
1943
1944 static void __kprobes disarm_all_kprobes(void)
1945 {
1946         struct hlist_head *head;
1947         struct hlist_node *node;
1948         struct kprobe *p;
1949         unsigned int i;
1950
1951         mutex_lock(&kprobe_mutex);
1952
1953         /* If kprobes are already disarmed, just return */
1954         if (kprobes_all_disarmed)
1955                 goto already_disabled;
1956
1957         kprobes_all_disarmed = true;
1958         printk(KERN_INFO "Kprobes globally disabled\n");
1959
1960         /*
1961          * Here we call get_online_cpus() for avoiding text_mutex deadlock,
1962          * because disarming may also unoptimize kprobes.
1963          */
1964         get_online_cpus();
1965         mutex_lock(&text_mutex);
1966         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1967                 head = &kprobe_table[i];
1968                 hlist_for_each_entry_rcu(p, node, head, hlist) {
1969                         if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
1970                                 __disarm_kprobe(p);
1971                 }
1972         }
1973
1974         mutex_unlock(&text_mutex);
1975         put_online_cpus();
1976         mutex_unlock(&kprobe_mutex);
1977         /* Allow all currently running kprobes to complete */
1978         synchronize_sched();
1979         return;
1980
1981 already_disabled:
1982         mutex_unlock(&kprobe_mutex);
1983         return;
1984 }
1985
1986 /*
1987  * XXX: The debugfs bool file interface doesn't allow for callbacks
1988  * when the bool state is switched. We can reuse that facility when
1989  * available
1990  */
1991 static ssize_t read_enabled_file_bool(struct file *file,
1992                char __user *user_buf, size_t count, loff_t *ppos)
1993 {
1994         char buf[3];
1995
1996         if (!kprobes_all_disarmed)
1997                 buf[0] = '1';
1998         else
1999                 buf[0] = '0';
2000         buf[1] = '\n';
2001         buf[2] = 0x00;
2002         return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
2003 }
2004
2005 static ssize_t write_enabled_file_bool(struct file *file,
2006                const char __user *user_buf, size_t count, loff_t *ppos)
2007 {
2008         char buf[32];
2009         int buf_size;
2010
2011         buf_size = min(count, (sizeof(buf)-1));
2012         if (copy_from_user(buf, user_buf, buf_size))
2013                 return -EFAULT;
2014
2015         switch (buf[0]) {
2016         case 'y':
2017         case 'Y':
2018         case '1':
2019                 arm_all_kprobes();
2020                 break;
2021         case 'n':
2022         case 'N':
2023         case '0':
2024                 disarm_all_kprobes();
2025                 break;
2026         }
2027
2028         return count;
2029 }
2030
2031 static const struct file_operations fops_kp = {
2032         .read =         read_enabled_file_bool,
2033         .write =        write_enabled_file_bool,
2034         .llseek =       default_llseek,
2035 };
2036
2037 static int __kprobes debugfs_kprobe_init(void)
2038 {
2039         struct dentry *dir, *file;
2040         unsigned int value = 1;
2041
2042         dir = debugfs_create_dir("kprobes", NULL);
2043         if (!dir)
2044                 return -ENOMEM;
2045
2046         file = debugfs_create_file("list", 0444, dir, NULL,
2047                                 &debugfs_kprobes_operations);
2048         if (!file) {
2049                 debugfs_remove(dir);
2050                 return -ENOMEM;
2051         }
2052
2053         file = debugfs_create_file("enabled", 0600, dir,
2054                                         &value, &fops_kp);
2055         if (!file) {
2056                 debugfs_remove(dir);
2057                 return -ENOMEM;
2058         }
2059
2060         return 0;
2061 }
2062
2063 late_initcall(debugfs_kprobe_init);
2064 #endif /* CONFIG_DEBUG_FS */
2065
2066 module_init(init_kprobes);
2067
2068 /* defined in arch/.../kernel/kprobes.c */
2069 EXPORT_SYMBOL_GPL(jprobe_return);