const: constify remaining file_operations
[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/kdebug.h>
46 #include <linux/memory.h>
47
48 #include <asm-generic/sections.h>
49 #include <asm/cacheflush.h>
50 #include <asm/errno.h>
51 #include <asm/uaccess.h>
52
53 #define KPROBE_HASH_BITS 6
54 #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
55
56
57 /*
58  * Some oddball architectures like 64bit powerpc have function descriptors
59  * so this must be overridable.
60  */
61 #ifndef kprobe_lookup_name
62 #define kprobe_lookup_name(name, addr) \
63         addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name)))
64 #endif
65
66 static int kprobes_initialized;
67 static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
68 static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
69
70 /* NOTE: change this value only with kprobe_mutex held */
71 static bool kprobes_all_disarmed;
72
73 static DEFINE_MUTEX(kprobe_mutex);      /* Protects kprobe_table */
74 static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
75 static struct {
76         spinlock_t lock ____cacheline_aligned_in_smp;
77 } kretprobe_table_locks[KPROBE_TABLE_SIZE];
78
79 static spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
80 {
81         return &(kretprobe_table_locks[hash].lock);
82 }
83
84 /*
85  * Normally, functions that we'd want to prohibit kprobes in, are marked
86  * __kprobes. But, there are cases where such functions already belong to
87  * a different section (__sched for preempt_schedule)
88  *
89  * For such cases, we now have a blacklist
90  */
91 static struct kprobe_blackpoint kprobe_blacklist[] = {
92         {"preempt_schedule",},
93         {NULL}    /* Terminator */
94 };
95
96 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
97 /*
98  * kprobe->ainsn.insn points to the copy of the instruction to be
99  * single-stepped. x86_64, POWER4 and above have no-exec support and
100  * stepping on the instruction on a vmalloced/kmalloced/data page
101  * is a recipe for disaster
102  */
103 #define INSNS_PER_PAGE  (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
104
105 struct kprobe_insn_page {
106         struct list_head list;
107         kprobe_opcode_t *insns;         /* Page of instruction slots */
108         char slot_used[INSNS_PER_PAGE];
109         int nused;
110         int ngarbage;
111 };
112
113 enum kprobe_slot_state {
114         SLOT_CLEAN = 0,
115         SLOT_DIRTY = 1,
116         SLOT_USED = 2,
117 };
118
119 static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_pages */
120 static LIST_HEAD(kprobe_insn_pages);
121 static int kprobe_garbage_slots;
122 static int collect_garbage_slots(void);
123
124 static int __kprobes check_safety(void)
125 {
126         int ret = 0;
127 #if defined(CONFIG_PREEMPT) && defined(CONFIG_FREEZER)
128         ret = freeze_processes();
129         if (ret == 0) {
130                 struct task_struct *p, *q;
131                 do_each_thread(p, q) {
132                         if (p != current && p->state == TASK_RUNNING &&
133                             p->pid != 0) {
134                                 printk("Check failed: %s is running\n",p->comm);
135                                 ret = -1;
136                                 goto loop_end;
137                         }
138                 } while_each_thread(p, q);
139         }
140 loop_end:
141         thaw_processes();
142 #else
143         synchronize_sched();
144 #endif
145         return ret;
146 }
147
148 /**
149  * __get_insn_slot() - Find a slot on an executable page for an instruction.
150  * We allocate an executable page if there's no room on existing ones.
151  */
152 static kprobe_opcode_t __kprobes *__get_insn_slot(void)
153 {
154         struct kprobe_insn_page *kip;
155
156  retry:
157         list_for_each_entry(kip, &kprobe_insn_pages, list) {
158                 if (kip->nused < INSNS_PER_PAGE) {
159                         int i;
160                         for (i = 0; i < INSNS_PER_PAGE; i++) {
161                                 if (kip->slot_used[i] == SLOT_CLEAN) {
162                                         kip->slot_used[i] = SLOT_USED;
163                                         kip->nused++;
164                                         return kip->insns + (i * MAX_INSN_SIZE);
165                                 }
166                         }
167                         /* Surprise!  No unused slots.  Fix kip->nused. */
168                         kip->nused = INSNS_PER_PAGE;
169                 }
170         }
171
172         /* If there are any garbage slots, collect it and try again. */
173         if (kprobe_garbage_slots && collect_garbage_slots() == 0) {
174                 goto retry;
175         }
176         /* All out of space.  Need to allocate a new page. Use slot 0. */
177         kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL);
178         if (!kip)
179                 return NULL;
180
181         /*
182          * Use module_alloc so this page is within +/- 2GB of where the
183          * kernel image and loaded module images reside. This is required
184          * so x86_64 can correctly handle the %rip-relative fixups.
185          */
186         kip->insns = module_alloc(PAGE_SIZE);
187         if (!kip->insns) {
188                 kfree(kip);
189                 return NULL;
190         }
191         INIT_LIST_HEAD(&kip->list);
192         list_add(&kip->list, &kprobe_insn_pages);
193         memset(kip->slot_used, SLOT_CLEAN, INSNS_PER_PAGE);
194         kip->slot_used[0] = SLOT_USED;
195         kip->nused = 1;
196         kip->ngarbage = 0;
197         return kip->insns;
198 }
199
200 kprobe_opcode_t __kprobes *get_insn_slot(void)
201 {
202         kprobe_opcode_t *ret;
203         mutex_lock(&kprobe_insn_mutex);
204         ret = __get_insn_slot();
205         mutex_unlock(&kprobe_insn_mutex);
206         return ret;
207 }
208
209 /* Return 1 if all garbages are collected, otherwise 0. */
210 static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
211 {
212         kip->slot_used[idx] = SLOT_CLEAN;
213         kip->nused--;
214         if (kip->nused == 0) {
215                 /*
216                  * Page is no longer in use.  Free it unless
217                  * it's the last one.  We keep the last one
218                  * so as not to have to set it up again the
219                  * next time somebody inserts a probe.
220                  */
221                 if (!list_is_singular(&kprobe_insn_pages)) {
222                         list_del(&kip->list);
223                         module_free(NULL, kip->insns);
224                         kfree(kip);
225                 }
226                 return 1;
227         }
228         return 0;
229 }
230
231 static int __kprobes collect_garbage_slots(void)
232 {
233         struct kprobe_insn_page *kip, *next;
234
235         /* Ensure no-one is preepmted on the garbages */
236         if (check_safety())
237                 return -EAGAIN;
238
239         list_for_each_entry_safe(kip, next, &kprobe_insn_pages, list) {
240                 int i;
241                 if (kip->ngarbage == 0)
242                         continue;
243                 kip->ngarbage = 0;      /* we will collect all garbages */
244                 for (i = 0; i < INSNS_PER_PAGE; i++) {
245                         if (kip->slot_used[i] == SLOT_DIRTY &&
246                             collect_one_slot(kip, i))
247                                 break;
248                 }
249         }
250         kprobe_garbage_slots = 0;
251         return 0;
252 }
253
254 void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
255 {
256         struct kprobe_insn_page *kip;
257
258         mutex_lock(&kprobe_insn_mutex);
259         list_for_each_entry(kip, &kprobe_insn_pages, list) {
260                 if (kip->insns <= slot &&
261                     slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) {
262                         int i = (slot - kip->insns) / MAX_INSN_SIZE;
263                         if (dirty) {
264                                 kip->slot_used[i] = SLOT_DIRTY;
265                                 kip->ngarbage++;
266                         } else
267                                 collect_one_slot(kip, i);
268                         break;
269                 }
270         }
271
272         if (dirty && ++kprobe_garbage_slots > INSNS_PER_PAGE)
273                 collect_garbage_slots();
274
275         mutex_unlock(&kprobe_insn_mutex);
276 }
277 #endif
278
279 /* We have preemption disabled.. so it is safe to use __ versions */
280 static inline void set_kprobe_instance(struct kprobe *kp)
281 {
282         __get_cpu_var(kprobe_instance) = kp;
283 }
284
285 static inline void reset_kprobe_instance(void)
286 {
287         __get_cpu_var(kprobe_instance) = NULL;
288 }
289
290 /*
291  * This routine is called either:
292  *      - under the kprobe_mutex - during kprobe_[un]register()
293  *                              OR
294  *      - with preemption disabled - from arch/xxx/kernel/kprobes.c
295  */
296 struct kprobe __kprobes *get_kprobe(void *addr)
297 {
298         struct hlist_head *head;
299         struct hlist_node *node;
300         struct kprobe *p;
301
302         head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
303         hlist_for_each_entry_rcu(p, node, head, hlist) {
304                 if (p->addr == addr)
305                         return p;
306         }
307         return NULL;
308 }
309
310 /* Arm a kprobe with text_mutex */
311 static void __kprobes arm_kprobe(struct kprobe *kp)
312 {
313         mutex_lock(&text_mutex);
314         arch_arm_kprobe(kp);
315         mutex_unlock(&text_mutex);
316 }
317
318 /* Disarm a kprobe with text_mutex */
319 static void __kprobes disarm_kprobe(struct kprobe *kp)
320 {
321         mutex_lock(&text_mutex);
322         arch_disarm_kprobe(kp);
323         mutex_unlock(&text_mutex);
324 }
325
326 /*
327  * Aggregate handlers for multiple kprobes support - these handlers
328  * take care of invoking the individual kprobe handlers on p->list
329  */
330 static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
331 {
332         struct kprobe *kp;
333
334         list_for_each_entry_rcu(kp, &p->list, list) {
335                 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
336                         set_kprobe_instance(kp);
337                         if (kp->pre_handler(kp, regs))
338                                 return 1;
339                 }
340                 reset_kprobe_instance();
341         }
342         return 0;
343 }
344
345 static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
346                                         unsigned long flags)
347 {
348         struct kprobe *kp;
349
350         list_for_each_entry_rcu(kp, &p->list, list) {
351                 if (kp->post_handler && likely(!kprobe_disabled(kp))) {
352                         set_kprobe_instance(kp);
353                         kp->post_handler(kp, regs, flags);
354                         reset_kprobe_instance();
355                 }
356         }
357 }
358
359 static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
360                                         int trapnr)
361 {
362         struct kprobe *cur = __get_cpu_var(kprobe_instance);
363
364         /*
365          * if we faulted "during" the execution of a user specified
366          * probe handler, invoke just that probe's fault handler
367          */
368         if (cur && cur->fault_handler) {
369                 if (cur->fault_handler(cur, regs, trapnr))
370                         return 1;
371         }
372         return 0;
373 }
374
375 static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
376 {
377         struct kprobe *cur = __get_cpu_var(kprobe_instance);
378         int ret = 0;
379
380         if (cur && cur->break_handler) {
381                 if (cur->break_handler(cur, regs))
382                         ret = 1;
383         }
384         reset_kprobe_instance();
385         return ret;
386 }
387
388 /* Walks the list and increments nmissed count for multiprobe case */
389 void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
390 {
391         struct kprobe *kp;
392         if (p->pre_handler != aggr_pre_handler) {
393                 p->nmissed++;
394         } else {
395                 list_for_each_entry_rcu(kp, &p->list, list)
396                         kp->nmissed++;
397         }
398         return;
399 }
400
401 void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
402                                 struct hlist_head *head)
403 {
404         struct kretprobe *rp = ri->rp;
405
406         /* remove rp inst off the rprobe_inst_table */
407         hlist_del(&ri->hlist);
408         INIT_HLIST_NODE(&ri->hlist);
409         if (likely(rp)) {
410                 spin_lock(&rp->lock);
411                 hlist_add_head(&ri->hlist, &rp->free_instances);
412                 spin_unlock(&rp->lock);
413         } else
414                 /* Unregistering */
415                 hlist_add_head(&ri->hlist, head);
416 }
417
418 void __kprobes kretprobe_hash_lock(struct task_struct *tsk,
419                          struct hlist_head **head, unsigned long *flags)
420 {
421         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
422         spinlock_t *hlist_lock;
423
424         *head = &kretprobe_inst_table[hash];
425         hlist_lock = kretprobe_table_lock_ptr(hash);
426         spin_lock_irqsave(hlist_lock, *flags);
427 }
428
429 static void __kprobes kretprobe_table_lock(unsigned long hash,
430         unsigned long *flags)
431 {
432         spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
433         spin_lock_irqsave(hlist_lock, *flags);
434 }
435
436 void __kprobes kretprobe_hash_unlock(struct task_struct *tsk,
437         unsigned long *flags)
438 {
439         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
440         spinlock_t *hlist_lock;
441
442         hlist_lock = kretprobe_table_lock_ptr(hash);
443         spin_unlock_irqrestore(hlist_lock, *flags);
444 }
445
446 void __kprobes kretprobe_table_unlock(unsigned long hash, unsigned long *flags)
447 {
448         spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
449         spin_unlock_irqrestore(hlist_lock, *flags);
450 }
451
452 /*
453  * This function is called from finish_task_switch when task tk becomes dead,
454  * so that we can recycle any function-return probe instances associated
455  * with this task. These left over instances represent probed functions
456  * that have been called but will never return.
457  */
458 void __kprobes kprobe_flush_task(struct task_struct *tk)
459 {
460         struct kretprobe_instance *ri;
461         struct hlist_head *head, empty_rp;
462         struct hlist_node *node, *tmp;
463         unsigned long hash, flags = 0;
464
465         if (unlikely(!kprobes_initialized))
466                 /* Early boot.  kretprobe_table_locks not yet initialized. */
467                 return;
468
469         hash = hash_ptr(tk, KPROBE_HASH_BITS);
470         head = &kretprobe_inst_table[hash];
471         kretprobe_table_lock(hash, &flags);
472         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
473                 if (ri->task == tk)
474                         recycle_rp_inst(ri, &empty_rp);
475         }
476         kretprobe_table_unlock(hash, &flags);
477         INIT_HLIST_HEAD(&empty_rp);
478         hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
479                 hlist_del(&ri->hlist);
480                 kfree(ri);
481         }
482 }
483
484 static inline void free_rp_inst(struct kretprobe *rp)
485 {
486         struct kretprobe_instance *ri;
487         struct hlist_node *pos, *next;
488
489         hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, hlist) {
490                 hlist_del(&ri->hlist);
491                 kfree(ri);
492         }
493 }
494
495 static void __kprobes cleanup_rp_inst(struct kretprobe *rp)
496 {
497         unsigned long flags, hash;
498         struct kretprobe_instance *ri;
499         struct hlist_node *pos, *next;
500         struct hlist_head *head;
501
502         /* No race here */
503         for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
504                 kretprobe_table_lock(hash, &flags);
505                 head = &kretprobe_inst_table[hash];
506                 hlist_for_each_entry_safe(ri, pos, next, head, hlist) {
507                         if (ri->rp == rp)
508                                 ri->rp = NULL;
509                 }
510                 kretprobe_table_unlock(hash, &flags);
511         }
512         free_rp_inst(rp);
513 }
514
515 /*
516  * Keep all fields in the kprobe consistent
517  */
518 static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p)
519 {
520         memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t));
521         memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn));
522 }
523
524 /*
525 * Add the new probe to ap->list. Fail if this is the
526 * second jprobe at the address - two jprobes can't coexist
527 */
528 static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p)
529 {
530         BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
531         if (p->break_handler) {
532                 if (ap->break_handler)
533                         return -EEXIST;
534                 list_add_tail_rcu(&p->list, &ap->list);
535                 ap->break_handler = aggr_break_handler;
536         } else
537                 list_add_rcu(&p->list, &ap->list);
538         if (p->post_handler && !ap->post_handler)
539                 ap->post_handler = aggr_post_handler;
540
541         if (kprobe_disabled(ap) && !kprobe_disabled(p)) {
542                 ap->flags &= ~KPROBE_FLAG_DISABLED;
543                 if (!kprobes_all_disarmed)
544                         /* Arm the breakpoint again. */
545                         arm_kprobe(ap);
546         }
547         return 0;
548 }
549
550 /*
551  * Fill in the required fields of the "manager kprobe". Replace the
552  * earlier kprobe in the hlist with the manager kprobe
553  */
554 static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
555 {
556         copy_kprobe(p, ap);
557         flush_insn_slot(ap);
558         ap->addr = p->addr;
559         ap->flags = p->flags;
560         ap->pre_handler = aggr_pre_handler;
561         ap->fault_handler = aggr_fault_handler;
562         /* We don't care the kprobe which has gone. */
563         if (p->post_handler && !kprobe_gone(p))
564                 ap->post_handler = aggr_post_handler;
565         if (p->break_handler && !kprobe_gone(p))
566                 ap->break_handler = aggr_break_handler;
567
568         INIT_LIST_HEAD(&ap->list);
569         list_add_rcu(&p->list, &ap->list);
570
571         hlist_replace_rcu(&p->hlist, &ap->hlist);
572 }
573
574 /*
575  * This is the second or subsequent kprobe at the address - handle
576  * the intricacies
577  */
578 static int __kprobes register_aggr_kprobe(struct kprobe *old_p,
579                                           struct kprobe *p)
580 {
581         int ret = 0;
582         struct kprobe *ap = old_p;
583
584         if (old_p->pre_handler != aggr_pre_handler) {
585                 /* If old_p is not an aggr_probe, create new aggr_kprobe. */
586                 ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL);
587                 if (!ap)
588                         return -ENOMEM;
589                 add_aggr_kprobe(ap, old_p);
590         }
591
592         if (kprobe_gone(ap)) {
593                 /*
594                  * Attempting to insert new probe at the same location that
595                  * had a probe in the module vaddr area which already
596                  * freed. So, the instruction slot has already been
597                  * released. We need a new slot for the new probe.
598                  */
599                 ret = arch_prepare_kprobe(ap);
600                 if (ret)
601                         /*
602                          * Even if fail to allocate new slot, don't need to
603                          * free aggr_probe. It will be used next time, or
604                          * freed by unregister_kprobe.
605                          */
606                         return ret;
607
608                 /*
609                  * Clear gone flag to prevent allocating new slot again, and
610                  * set disabled flag because it is not armed yet.
611                  */
612                 ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
613                             | KPROBE_FLAG_DISABLED;
614         }
615
616         copy_kprobe(ap, p);
617         return add_new_kprobe(ap, p);
618 }
619
620 /* Try to disable aggr_kprobe, and return 1 if succeeded.*/
621 static int __kprobes try_to_disable_aggr_kprobe(struct kprobe *p)
622 {
623         struct kprobe *kp;
624
625         list_for_each_entry_rcu(kp, &p->list, list) {
626                 if (!kprobe_disabled(kp))
627                         /*
628                          * There is an active probe on the list.
629                          * We can't disable aggr_kprobe.
630                          */
631                         return 0;
632         }
633         p->flags |= KPROBE_FLAG_DISABLED;
634         return 1;
635 }
636
637 static int __kprobes in_kprobes_functions(unsigned long addr)
638 {
639         struct kprobe_blackpoint *kb;
640
641         if (addr >= (unsigned long)__kprobes_text_start &&
642             addr < (unsigned long)__kprobes_text_end)
643                 return -EINVAL;
644         /*
645          * If there exists a kprobe_blacklist, verify and
646          * fail any probe registration in the prohibited area
647          */
648         for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
649                 if (kb->start_addr) {
650                         if (addr >= kb->start_addr &&
651                             addr < (kb->start_addr + kb->range))
652                                 return -EINVAL;
653                 }
654         }
655         return 0;
656 }
657
658 /*
659  * If we have a symbol_name argument, look it up and add the offset field
660  * to it. This way, we can specify a relative address to a symbol.
661  */
662 static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p)
663 {
664         kprobe_opcode_t *addr = p->addr;
665         if (p->symbol_name) {
666                 if (addr)
667                         return NULL;
668                 kprobe_lookup_name(p->symbol_name, addr);
669         }
670
671         if (!addr)
672                 return NULL;
673         return (kprobe_opcode_t *)(((char *)addr) + p->offset);
674 }
675
676 int __kprobes register_kprobe(struct kprobe *p)
677 {
678         int ret = 0;
679         struct kprobe *old_p;
680         struct module *probed_mod;
681         kprobe_opcode_t *addr;
682
683         addr = kprobe_addr(p);
684         if (!addr)
685                 return -EINVAL;
686         p->addr = addr;
687
688         preempt_disable();
689         if (!kernel_text_address((unsigned long) p->addr) ||
690             in_kprobes_functions((unsigned long) p->addr)) {
691                 preempt_enable();
692                 return -EINVAL;
693         }
694
695         /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
696         p->flags &= KPROBE_FLAG_DISABLED;
697
698         /*
699          * Check if are we probing a module.
700          */
701         probed_mod = __module_text_address((unsigned long) p->addr);
702         if (probed_mod) {
703                 /*
704                  * We must hold a refcount of the probed module while updating
705                  * its code to prohibit unexpected unloading.
706                  */
707                 if (unlikely(!try_module_get(probed_mod))) {
708                         preempt_enable();
709                         return -EINVAL;
710                 }
711                 /*
712                  * If the module freed .init.text, we couldn't insert
713                  * kprobes in there.
714                  */
715                 if (within_module_init((unsigned long)p->addr, probed_mod) &&
716                     probed_mod->state != MODULE_STATE_COMING) {
717                         module_put(probed_mod);
718                         preempt_enable();
719                         return -EINVAL;
720                 }
721         }
722         preempt_enable();
723
724         p->nmissed = 0;
725         INIT_LIST_HEAD(&p->list);
726         mutex_lock(&kprobe_mutex);
727         old_p = get_kprobe(p->addr);
728         if (old_p) {
729                 ret = register_aggr_kprobe(old_p, p);
730                 goto out;
731         }
732
733         mutex_lock(&text_mutex);
734         ret = arch_prepare_kprobe(p);
735         if (ret)
736                 goto out_unlock_text;
737
738         INIT_HLIST_NODE(&p->hlist);
739         hlist_add_head_rcu(&p->hlist,
740                        &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
741
742         if (!kprobes_all_disarmed && !kprobe_disabled(p))
743                 arch_arm_kprobe(p);
744
745 out_unlock_text:
746         mutex_unlock(&text_mutex);
747 out:
748         mutex_unlock(&kprobe_mutex);
749
750         if (probed_mod)
751                 module_put(probed_mod);
752
753         return ret;
754 }
755 EXPORT_SYMBOL_GPL(register_kprobe);
756
757 /* Check passed kprobe is valid and return kprobe in kprobe_table. */
758 static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p)
759 {
760         struct kprobe *old_p, *list_p;
761
762         old_p = get_kprobe(p->addr);
763         if (unlikely(!old_p))
764                 return NULL;
765
766         if (p != old_p) {
767                 list_for_each_entry_rcu(list_p, &old_p->list, list)
768                         if (list_p == p)
769                         /* kprobe p is a valid probe */
770                                 goto valid;
771                 return NULL;
772         }
773 valid:
774         return old_p;
775 }
776
777 /*
778  * Unregister a kprobe without a scheduler synchronization.
779  */
780 static int __kprobes __unregister_kprobe_top(struct kprobe *p)
781 {
782         struct kprobe *old_p, *list_p;
783
784         old_p = __get_valid_kprobe(p);
785         if (old_p == NULL)
786                 return -EINVAL;
787
788         if (old_p == p ||
789             (old_p->pre_handler == aggr_pre_handler &&
790              list_is_singular(&old_p->list))) {
791                 /*
792                  * Only probe on the hash list. Disarm only if kprobes are
793                  * enabled and not gone - otherwise, the breakpoint would
794                  * already have been removed. We save on flushing icache.
795                  */
796                 if (!kprobes_all_disarmed && !kprobe_disabled(old_p))
797                         disarm_kprobe(p);
798                 hlist_del_rcu(&old_p->hlist);
799         } else {
800                 if (p->break_handler && !kprobe_gone(p))
801                         old_p->break_handler = NULL;
802                 if (p->post_handler && !kprobe_gone(p)) {
803                         list_for_each_entry_rcu(list_p, &old_p->list, list) {
804                                 if ((list_p != p) && (list_p->post_handler))
805                                         goto noclean;
806                         }
807                         old_p->post_handler = NULL;
808                 }
809 noclean:
810                 list_del_rcu(&p->list);
811                 if (!kprobe_disabled(old_p)) {
812                         try_to_disable_aggr_kprobe(old_p);
813                         if (!kprobes_all_disarmed && kprobe_disabled(old_p))
814                                 disarm_kprobe(old_p);
815                 }
816         }
817         return 0;
818 }
819
820 static void __kprobes __unregister_kprobe_bottom(struct kprobe *p)
821 {
822         struct kprobe *old_p;
823
824         if (list_empty(&p->list))
825                 arch_remove_kprobe(p);
826         else if (list_is_singular(&p->list)) {
827                 /* "p" is the last child of an aggr_kprobe */
828                 old_p = list_entry(p->list.next, struct kprobe, list);
829                 list_del(&p->list);
830                 arch_remove_kprobe(old_p);
831                 kfree(old_p);
832         }
833 }
834
835 int __kprobes register_kprobes(struct kprobe **kps, int num)
836 {
837         int i, ret = 0;
838
839         if (num <= 0)
840                 return -EINVAL;
841         for (i = 0; i < num; i++) {
842                 ret = register_kprobe(kps[i]);
843                 if (ret < 0) {
844                         if (i > 0)
845                                 unregister_kprobes(kps, i);
846                         break;
847                 }
848         }
849         return ret;
850 }
851 EXPORT_SYMBOL_GPL(register_kprobes);
852
853 void __kprobes unregister_kprobe(struct kprobe *p)
854 {
855         unregister_kprobes(&p, 1);
856 }
857 EXPORT_SYMBOL_GPL(unregister_kprobe);
858
859 void __kprobes unregister_kprobes(struct kprobe **kps, int num)
860 {
861         int i;
862
863         if (num <= 0)
864                 return;
865         mutex_lock(&kprobe_mutex);
866         for (i = 0; i < num; i++)
867                 if (__unregister_kprobe_top(kps[i]) < 0)
868                         kps[i]->addr = NULL;
869         mutex_unlock(&kprobe_mutex);
870
871         synchronize_sched();
872         for (i = 0; i < num; i++)
873                 if (kps[i]->addr)
874                         __unregister_kprobe_bottom(kps[i]);
875 }
876 EXPORT_SYMBOL_GPL(unregister_kprobes);
877
878 static struct notifier_block kprobe_exceptions_nb = {
879         .notifier_call = kprobe_exceptions_notify,
880         .priority = 0x7fffffff /* we need to be notified first */
881 };
882
883 unsigned long __weak arch_deref_entry_point(void *entry)
884 {
885         return (unsigned long)entry;
886 }
887
888 int __kprobes register_jprobes(struct jprobe **jps, int num)
889 {
890         struct jprobe *jp;
891         int ret = 0, i;
892
893         if (num <= 0)
894                 return -EINVAL;
895         for (i = 0; i < num; i++) {
896                 unsigned long addr;
897                 jp = jps[i];
898                 addr = arch_deref_entry_point(jp->entry);
899
900                 if (!kernel_text_address(addr))
901                         ret = -EINVAL;
902                 else {
903                         /* Todo: Verify probepoint is a function entry point */
904                         jp->kp.pre_handler = setjmp_pre_handler;
905                         jp->kp.break_handler = longjmp_break_handler;
906                         ret = register_kprobe(&jp->kp);
907                 }
908                 if (ret < 0) {
909                         if (i > 0)
910                                 unregister_jprobes(jps, i);
911                         break;
912                 }
913         }
914         return ret;
915 }
916 EXPORT_SYMBOL_GPL(register_jprobes);
917
918 int __kprobes register_jprobe(struct jprobe *jp)
919 {
920         return register_jprobes(&jp, 1);
921 }
922 EXPORT_SYMBOL_GPL(register_jprobe);
923
924 void __kprobes unregister_jprobe(struct jprobe *jp)
925 {
926         unregister_jprobes(&jp, 1);
927 }
928 EXPORT_SYMBOL_GPL(unregister_jprobe);
929
930 void __kprobes unregister_jprobes(struct jprobe **jps, int num)
931 {
932         int i;
933
934         if (num <= 0)
935                 return;
936         mutex_lock(&kprobe_mutex);
937         for (i = 0; i < num; i++)
938                 if (__unregister_kprobe_top(&jps[i]->kp) < 0)
939                         jps[i]->kp.addr = NULL;
940         mutex_unlock(&kprobe_mutex);
941
942         synchronize_sched();
943         for (i = 0; i < num; i++) {
944                 if (jps[i]->kp.addr)
945                         __unregister_kprobe_bottom(&jps[i]->kp);
946         }
947 }
948 EXPORT_SYMBOL_GPL(unregister_jprobes);
949
950 #ifdef CONFIG_KRETPROBES
951 /*
952  * This kprobe pre_handler is registered with every kretprobe. When probe
953  * hits it will set up the return probe.
954  */
955 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
956                                            struct pt_regs *regs)
957 {
958         struct kretprobe *rp = container_of(p, struct kretprobe, kp);
959         unsigned long hash, flags = 0;
960         struct kretprobe_instance *ri;
961
962         /*TODO: consider to only swap the RA after the last pre_handler fired */
963         hash = hash_ptr(current, KPROBE_HASH_BITS);
964         spin_lock_irqsave(&rp->lock, flags);
965         if (!hlist_empty(&rp->free_instances)) {
966                 ri = hlist_entry(rp->free_instances.first,
967                                 struct kretprobe_instance, hlist);
968                 hlist_del(&ri->hlist);
969                 spin_unlock_irqrestore(&rp->lock, flags);
970
971                 ri->rp = rp;
972                 ri->task = current;
973
974                 if (rp->entry_handler && rp->entry_handler(ri, regs))
975                         return 0;
976
977                 arch_prepare_kretprobe(ri, regs);
978
979                 /* XXX(hch): why is there no hlist_move_head? */
980                 INIT_HLIST_NODE(&ri->hlist);
981                 kretprobe_table_lock(hash, &flags);
982                 hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
983                 kretprobe_table_unlock(hash, &flags);
984         } else {
985                 rp->nmissed++;
986                 spin_unlock_irqrestore(&rp->lock, flags);
987         }
988         return 0;
989 }
990
991 int __kprobes register_kretprobe(struct kretprobe *rp)
992 {
993         int ret = 0;
994         struct kretprobe_instance *inst;
995         int i;
996         void *addr;
997
998         if (kretprobe_blacklist_size) {
999                 addr = kprobe_addr(&rp->kp);
1000                 if (!addr)
1001                         return -EINVAL;
1002
1003                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1004                         if (kretprobe_blacklist[i].addr == addr)
1005                                 return -EINVAL;
1006                 }
1007         }
1008
1009         rp->kp.pre_handler = pre_handler_kretprobe;
1010         rp->kp.post_handler = NULL;
1011         rp->kp.fault_handler = NULL;
1012         rp->kp.break_handler = NULL;
1013
1014         /* Pre-allocate memory for max kretprobe instances */
1015         if (rp->maxactive <= 0) {
1016 #ifdef CONFIG_PREEMPT
1017                 rp->maxactive = max(10, 2 * NR_CPUS);
1018 #else
1019                 rp->maxactive = NR_CPUS;
1020 #endif
1021         }
1022         spin_lock_init(&rp->lock);
1023         INIT_HLIST_HEAD(&rp->free_instances);
1024         for (i = 0; i < rp->maxactive; i++) {
1025                 inst = kmalloc(sizeof(struct kretprobe_instance) +
1026                                rp->data_size, GFP_KERNEL);
1027                 if (inst == NULL) {
1028                         free_rp_inst(rp);
1029                         return -ENOMEM;
1030                 }
1031                 INIT_HLIST_NODE(&inst->hlist);
1032                 hlist_add_head(&inst->hlist, &rp->free_instances);
1033         }
1034
1035         rp->nmissed = 0;
1036         /* Establish function entry probe point */
1037         ret = register_kprobe(&rp->kp);
1038         if (ret != 0)
1039                 free_rp_inst(rp);
1040         return ret;
1041 }
1042 EXPORT_SYMBOL_GPL(register_kretprobe);
1043
1044 int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1045 {
1046         int ret = 0, i;
1047
1048         if (num <= 0)
1049                 return -EINVAL;
1050         for (i = 0; i < num; i++) {
1051                 ret = register_kretprobe(rps[i]);
1052                 if (ret < 0) {
1053                         if (i > 0)
1054                                 unregister_kretprobes(rps, i);
1055                         break;
1056                 }
1057         }
1058         return ret;
1059 }
1060 EXPORT_SYMBOL_GPL(register_kretprobes);
1061
1062 void __kprobes unregister_kretprobe(struct kretprobe *rp)
1063 {
1064         unregister_kretprobes(&rp, 1);
1065 }
1066 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1067
1068 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1069 {
1070         int i;
1071
1072         if (num <= 0)
1073                 return;
1074         mutex_lock(&kprobe_mutex);
1075         for (i = 0; i < num; i++)
1076                 if (__unregister_kprobe_top(&rps[i]->kp) < 0)
1077                         rps[i]->kp.addr = NULL;
1078         mutex_unlock(&kprobe_mutex);
1079
1080         synchronize_sched();
1081         for (i = 0; i < num; i++) {
1082                 if (rps[i]->kp.addr) {
1083                         __unregister_kprobe_bottom(&rps[i]->kp);
1084                         cleanup_rp_inst(rps[i]);
1085                 }
1086         }
1087 }
1088 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1089
1090 #else /* CONFIG_KRETPROBES */
1091 int __kprobes register_kretprobe(struct kretprobe *rp)
1092 {
1093         return -ENOSYS;
1094 }
1095 EXPORT_SYMBOL_GPL(register_kretprobe);
1096
1097 int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1098 {
1099         return -ENOSYS;
1100 }
1101 EXPORT_SYMBOL_GPL(register_kretprobes);
1102
1103 void __kprobes unregister_kretprobe(struct kretprobe *rp)
1104 {
1105 }
1106 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1107
1108 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1109 {
1110 }
1111 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1112
1113 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
1114                                            struct pt_regs *regs)
1115 {
1116         return 0;
1117 }
1118
1119 #endif /* CONFIG_KRETPROBES */
1120
1121 /* Set the kprobe gone and remove its instruction buffer. */
1122 static void __kprobes kill_kprobe(struct kprobe *p)
1123 {
1124         struct kprobe *kp;
1125
1126         p->flags |= KPROBE_FLAG_GONE;
1127         if (p->pre_handler == aggr_pre_handler) {
1128                 /*
1129                  * If this is an aggr_kprobe, we have to list all the
1130                  * chained probes and mark them GONE.
1131                  */
1132                 list_for_each_entry_rcu(kp, &p->list, list)
1133                         kp->flags |= KPROBE_FLAG_GONE;
1134                 p->post_handler = NULL;
1135                 p->break_handler = NULL;
1136         }
1137         /*
1138          * Here, we can remove insn_slot safely, because no thread calls
1139          * the original probed function (which will be freed soon) any more.
1140          */
1141         arch_remove_kprobe(p);
1142 }
1143
1144 /* Module notifier call back, checking kprobes on the module */
1145 static int __kprobes kprobes_module_callback(struct notifier_block *nb,
1146                                              unsigned long val, void *data)
1147 {
1148         struct module *mod = data;
1149         struct hlist_head *head;
1150         struct hlist_node *node;
1151         struct kprobe *p;
1152         unsigned int i;
1153         int checkcore = (val == MODULE_STATE_GOING);
1154
1155         if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
1156                 return NOTIFY_DONE;
1157
1158         /*
1159          * When MODULE_STATE_GOING was notified, both of module .text and
1160          * .init.text sections would be freed. When MODULE_STATE_LIVE was
1161          * notified, only .init.text section would be freed. We need to
1162          * disable kprobes which have been inserted in the sections.
1163          */
1164         mutex_lock(&kprobe_mutex);
1165         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1166                 head = &kprobe_table[i];
1167                 hlist_for_each_entry_rcu(p, node, head, hlist)
1168                         if (within_module_init((unsigned long)p->addr, mod) ||
1169                             (checkcore &&
1170                              within_module_core((unsigned long)p->addr, mod))) {
1171                                 /*
1172                                  * The vaddr this probe is installed will soon
1173                                  * be vfreed buy not synced to disk. Hence,
1174                                  * disarming the breakpoint isn't needed.
1175                                  */
1176                                 kill_kprobe(p);
1177                         }
1178         }
1179         mutex_unlock(&kprobe_mutex);
1180         return NOTIFY_DONE;
1181 }
1182
1183 static struct notifier_block kprobe_module_nb = {
1184         .notifier_call = kprobes_module_callback,
1185         .priority = 0
1186 };
1187
1188 static int __init init_kprobes(void)
1189 {
1190         int i, err = 0;
1191         unsigned long offset = 0, size = 0;
1192         char *modname, namebuf[128];
1193         const char *symbol_name;
1194         void *addr;
1195         struct kprobe_blackpoint *kb;
1196
1197         /* FIXME allocate the probe table, currently defined statically */
1198         /* initialize all list heads */
1199         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1200                 INIT_HLIST_HEAD(&kprobe_table[i]);
1201                 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
1202                 spin_lock_init(&(kretprobe_table_locks[i].lock));
1203         }
1204
1205         /*
1206          * Lookup and populate the kprobe_blacklist.
1207          *
1208          * Unlike the kretprobe blacklist, we'll need to determine
1209          * the range of addresses that belong to the said functions,
1210          * since a kprobe need not necessarily be at the beginning
1211          * of a function.
1212          */
1213         for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
1214                 kprobe_lookup_name(kb->name, addr);
1215                 if (!addr)
1216                         continue;
1217
1218                 kb->start_addr = (unsigned long)addr;
1219                 symbol_name = kallsyms_lookup(kb->start_addr,
1220                                 &size, &offset, &modname, namebuf);
1221                 if (!symbol_name)
1222                         kb->range = 0;
1223                 else
1224                         kb->range = size;
1225         }
1226
1227         if (kretprobe_blacklist_size) {
1228                 /* lookup the function address from its name */
1229                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1230                         kprobe_lookup_name(kretprobe_blacklist[i].name,
1231                                            kretprobe_blacklist[i].addr);
1232                         if (!kretprobe_blacklist[i].addr)
1233                                 printk("kretprobe: lookup failed: %s\n",
1234                                        kretprobe_blacklist[i].name);
1235                 }
1236         }
1237
1238         /* By default, kprobes are armed */
1239         kprobes_all_disarmed = false;
1240
1241         err = arch_init_kprobes();
1242         if (!err)
1243                 err = register_die_notifier(&kprobe_exceptions_nb);
1244         if (!err)
1245                 err = register_module_notifier(&kprobe_module_nb);
1246
1247         kprobes_initialized = (err == 0);
1248
1249         if (!err)
1250                 init_test_probes();
1251         return err;
1252 }
1253
1254 #ifdef CONFIG_DEBUG_FS
1255 static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
1256                 const char *sym, int offset,char *modname)
1257 {
1258         char *kprobe_type;
1259
1260         if (p->pre_handler == pre_handler_kretprobe)
1261                 kprobe_type = "r";
1262         else if (p->pre_handler == setjmp_pre_handler)
1263                 kprobe_type = "j";
1264         else
1265                 kprobe_type = "k";
1266         if (sym)
1267                 seq_printf(pi, "%p  %s  %s+0x%x  %s %s%s\n",
1268                         p->addr, kprobe_type, sym, offset,
1269                         (modname ? modname : " "),
1270                         (kprobe_gone(p) ? "[GONE]" : ""),
1271                         ((kprobe_disabled(p) && !kprobe_gone(p)) ?
1272                          "[DISABLED]" : ""));
1273         else
1274                 seq_printf(pi, "%p  %s  %p %s%s\n",
1275                         p->addr, kprobe_type, p->addr,
1276                         (kprobe_gone(p) ? "[GONE]" : ""),
1277                         ((kprobe_disabled(p) && !kprobe_gone(p)) ?
1278                          "[DISABLED]" : ""));
1279 }
1280
1281 static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
1282 {
1283         return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
1284 }
1285
1286 static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
1287 {
1288         (*pos)++;
1289         if (*pos >= KPROBE_TABLE_SIZE)
1290                 return NULL;
1291         return pos;
1292 }
1293
1294 static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v)
1295 {
1296         /* Nothing to do */
1297 }
1298
1299 static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v)
1300 {
1301         struct hlist_head *head;
1302         struct hlist_node *node;
1303         struct kprobe *p, *kp;
1304         const char *sym = NULL;
1305         unsigned int i = *(loff_t *) v;
1306         unsigned long offset = 0;
1307         char *modname, namebuf[128];
1308
1309         head = &kprobe_table[i];
1310         preempt_disable();
1311         hlist_for_each_entry_rcu(p, node, head, hlist) {
1312                 sym = kallsyms_lookup((unsigned long)p->addr, NULL,
1313                                         &offset, &modname, namebuf);
1314                 if (p->pre_handler == aggr_pre_handler) {
1315                         list_for_each_entry_rcu(kp, &p->list, list)
1316                                 report_probe(pi, kp, sym, offset, modname);
1317                 } else
1318                         report_probe(pi, p, sym, offset, modname);
1319         }
1320         preempt_enable();
1321         return 0;
1322 }
1323
1324 static const struct seq_operations kprobes_seq_ops = {
1325         .start = kprobe_seq_start,
1326         .next  = kprobe_seq_next,
1327         .stop  = kprobe_seq_stop,
1328         .show  = show_kprobe_addr
1329 };
1330
1331 static int __kprobes kprobes_open(struct inode *inode, struct file *filp)
1332 {
1333         return seq_open(filp, &kprobes_seq_ops);
1334 }
1335
1336 static const struct file_operations debugfs_kprobes_operations = {
1337         .open           = kprobes_open,
1338         .read           = seq_read,
1339         .llseek         = seq_lseek,
1340         .release        = seq_release,
1341 };
1342
1343 /* Disable one kprobe */
1344 int __kprobes disable_kprobe(struct kprobe *kp)
1345 {
1346         int ret = 0;
1347         struct kprobe *p;
1348
1349         mutex_lock(&kprobe_mutex);
1350
1351         /* Check whether specified probe is valid. */
1352         p = __get_valid_kprobe(kp);
1353         if (unlikely(p == NULL)) {
1354                 ret = -EINVAL;
1355                 goto out;
1356         }
1357
1358         /* If the probe is already disabled (or gone), just return */
1359         if (kprobe_disabled(kp))
1360                 goto out;
1361
1362         kp->flags |= KPROBE_FLAG_DISABLED;
1363         if (p != kp)
1364                 /* When kp != p, p is always enabled. */
1365                 try_to_disable_aggr_kprobe(p);
1366
1367         if (!kprobes_all_disarmed && kprobe_disabled(p))
1368                 disarm_kprobe(p);
1369 out:
1370         mutex_unlock(&kprobe_mutex);
1371         return ret;
1372 }
1373 EXPORT_SYMBOL_GPL(disable_kprobe);
1374
1375 /* Enable one kprobe */
1376 int __kprobes enable_kprobe(struct kprobe *kp)
1377 {
1378         int ret = 0;
1379         struct kprobe *p;
1380
1381         mutex_lock(&kprobe_mutex);
1382
1383         /* Check whether specified probe is valid. */
1384         p = __get_valid_kprobe(kp);
1385         if (unlikely(p == NULL)) {
1386                 ret = -EINVAL;
1387                 goto out;
1388         }
1389
1390         if (kprobe_gone(kp)) {
1391                 /* This kprobe has gone, we couldn't enable it. */
1392                 ret = -EINVAL;
1393                 goto out;
1394         }
1395
1396         if (!kprobes_all_disarmed && kprobe_disabled(p))
1397                 arm_kprobe(p);
1398
1399         p->flags &= ~KPROBE_FLAG_DISABLED;
1400         if (p != kp)
1401                 kp->flags &= ~KPROBE_FLAG_DISABLED;
1402 out:
1403         mutex_unlock(&kprobe_mutex);
1404         return ret;
1405 }
1406 EXPORT_SYMBOL_GPL(enable_kprobe);
1407
1408 static void __kprobes arm_all_kprobes(void)
1409 {
1410         struct hlist_head *head;
1411         struct hlist_node *node;
1412         struct kprobe *p;
1413         unsigned int i;
1414
1415         mutex_lock(&kprobe_mutex);
1416
1417         /* If kprobes are armed, just return */
1418         if (!kprobes_all_disarmed)
1419                 goto already_enabled;
1420
1421         mutex_lock(&text_mutex);
1422         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1423                 head = &kprobe_table[i];
1424                 hlist_for_each_entry_rcu(p, node, head, hlist)
1425                         if (!kprobe_disabled(p))
1426                                 arch_arm_kprobe(p);
1427         }
1428         mutex_unlock(&text_mutex);
1429
1430         kprobes_all_disarmed = false;
1431         printk(KERN_INFO "Kprobes globally enabled\n");
1432
1433 already_enabled:
1434         mutex_unlock(&kprobe_mutex);
1435         return;
1436 }
1437
1438 static void __kprobes disarm_all_kprobes(void)
1439 {
1440         struct hlist_head *head;
1441         struct hlist_node *node;
1442         struct kprobe *p;
1443         unsigned int i;
1444
1445         mutex_lock(&kprobe_mutex);
1446
1447         /* If kprobes are already disarmed, just return */
1448         if (kprobes_all_disarmed)
1449                 goto already_disabled;
1450
1451         kprobes_all_disarmed = true;
1452         printk(KERN_INFO "Kprobes globally disabled\n");
1453         mutex_lock(&text_mutex);
1454         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1455                 head = &kprobe_table[i];
1456                 hlist_for_each_entry_rcu(p, node, head, hlist) {
1457                         if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
1458                                 arch_disarm_kprobe(p);
1459                 }
1460         }
1461
1462         mutex_unlock(&text_mutex);
1463         mutex_unlock(&kprobe_mutex);
1464         /* Allow all currently running kprobes to complete */
1465         synchronize_sched();
1466         return;
1467
1468 already_disabled:
1469         mutex_unlock(&kprobe_mutex);
1470         return;
1471 }
1472
1473 /*
1474  * XXX: The debugfs bool file interface doesn't allow for callbacks
1475  * when the bool state is switched. We can reuse that facility when
1476  * available
1477  */
1478 static ssize_t read_enabled_file_bool(struct file *file,
1479                char __user *user_buf, size_t count, loff_t *ppos)
1480 {
1481         char buf[3];
1482
1483         if (!kprobes_all_disarmed)
1484                 buf[0] = '1';
1485         else
1486                 buf[0] = '0';
1487         buf[1] = '\n';
1488         buf[2] = 0x00;
1489         return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
1490 }
1491
1492 static ssize_t write_enabled_file_bool(struct file *file,
1493                const char __user *user_buf, size_t count, loff_t *ppos)
1494 {
1495         char buf[32];
1496         int buf_size;
1497
1498         buf_size = min(count, (sizeof(buf)-1));
1499         if (copy_from_user(buf, user_buf, buf_size))
1500                 return -EFAULT;
1501
1502         switch (buf[0]) {
1503         case 'y':
1504         case 'Y':
1505         case '1':
1506                 arm_all_kprobes();
1507                 break;
1508         case 'n':
1509         case 'N':
1510         case '0':
1511                 disarm_all_kprobes();
1512                 break;
1513         }
1514
1515         return count;
1516 }
1517
1518 static const struct file_operations fops_kp = {
1519         .read =         read_enabled_file_bool,
1520         .write =        write_enabled_file_bool,
1521 };
1522
1523 static int __kprobes debugfs_kprobe_init(void)
1524 {
1525         struct dentry *dir, *file;
1526         unsigned int value = 1;
1527
1528         dir = debugfs_create_dir("kprobes", NULL);
1529         if (!dir)
1530                 return -ENOMEM;
1531
1532         file = debugfs_create_file("list", 0444, dir, NULL,
1533                                 &debugfs_kprobes_operations);
1534         if (!file) {
1535                 debugfs_remove(dir);
1536                 return -ENOMEM;
1537         }
1538
1539         file = debugfs_create_file("enabled", 0600, dir,
1540                                         &value, &fops_kp);
1541         if (!file) {
1542                 debugfs_remove(dir);
1543                 return -ENOMEM;
1544         }
1545
1546         return 0;
1547 }
1548
1549 late_initcall(debugfs_kprobe_init);
1550 #endif /* CONFIG_DEBUG_FS */
1551
1552 module_init(init_kprobes);
1553
1554 /* defined in arch/.../kernel/kprobes.c */
1555 EXPORT_SYMBOL_GPL(jprobe_return);