kprobes/x86-32: Move irq-exit functions to kprobes section
[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         {"native_get_debugreg",},
94         {"irq_entries_start",},
95         {"common_interrupt",},
96         {NULL}    /* Terminator */
97 };
98
99 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
100 /*
101  * kprobe->ainsn.insn points to the copy of the instruction to be
102  * single-stepped. x86_64, POWER4 and above have no-exec support and
103  * stepping on the instruction on a vmalloced/kmalloced/data page
104  * is a recipe for disaster
105  */
106 #define INSNS_PER_PAGE  (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
107
108 struct kprobe_insn_page {
109         struct list_head list;
110         kprobe_opcode_t *insns;         /* Page of instruction slots */
111         char slot_used[INSNS_PER_PAGE];
112         int nused;
113         int ngarbage;
114 };
115
116 enum kprobe_slot_state {
117         SLOT_CLEAN = 0,
118         SLOT_DIRTY = 1,
119         SLOT_USED = 2,
120 };
121
122 static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_pages */
123 static LIST_HEAD(kprobe_insn_pages);
124 static int kprobe_garbage_slots;
125 static int collect_garbage_slots(void);
126
127 static int __kprobes check_safety(void)
128 {
129         int ret = 0;
130 #if defined(CONFIG_PREEMPT) && defined(CONFIG_FREEZER)
131         ret = freeze_processes();
132         if (ret == 0) {
133                 struct task_struct *p, *q;
134                 do_each_thread(p, q) {
135                         if (p != current && p->state == TASK_RUNNING &&
136                             p->pid != 0) {
137                                 printk("Check failed: %s is running\n",p->comm);
138                                 ret = -1;
139                                 goto loop_end;
140                         }
141                 } while_each_thread(p, q);
142         }
143 loop_end:
144         thaw_processes();
145 #else
146         synchronize_sched();
147 #endif
148         return ret;
149 }
150
151 /**
152  * __get_insn_slot() - Find a slot on an executable page for an instruction.
153  * We allocate an executable page if there's no room on existing ones.
154  */
155 static kprobe_opcode_t __kprobes *__get_insn_slot(void)
156 {
157         struct kprobe_insn_page *kip;
158
159  retry:
160         list_for_each_entry(kip, &kprobe_insn_pages, list) {
161                 if (kip->nused < INSNS_PER_PAGE) {
162                         int i;
163                         for (i = 0; i < INSNS_PER_PAGE; i++) {
164                                 if (kip->slot_used[i] == SLOT_CLEAN) {
165                                         kip->slot_used[i] = SLOT_USED;
166                                         kip->nused++;
167                                         return kip->insns + (i * MAX_INSN_SIZE);
168                                 }
169                         }
170                         /* Surprise!  No unused slots.  Fix kip->nused. */
171                         kip->nused = INSNS_PER_PAGE;
172                 }
173         }
174
175         /* If there are any garbage slots, collect it and try again. */
176         if (kprobe_garbage_slots && collect_garbage_slots() == 0) {
177                 goto retry;
178         }
179         /* All out of space.  Need to allocate a new page. Use slot 0. */
180         kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL);
181         if (!kip)
182                 return NULL;
183
184         /*
185          * Use module_alloc so this page is within +/- 2GB of where the
186          * kernel image and loaded module images reside. This is required
187          * so x86_64 can correctly handle the %rip-relative fixups.
188          */
189         kip->insns = module_alloc(PAGE_SIZE);
190         if (!kip->insns) {
191                 kfree(kip);
192                 return NULL;
193         }
194         INIT_LIST_HEAD(&kip->list);
195         list_add(&kip->list, &kprobe_insn_pages);
196         memset(kip->slot_used, SLOT_CLEAN, INSNS_PER_PAGE);
197         kip->slot_used[0] = SLOT_USED;
198         kip->nused = 1;
199         kip->ngarbage = 0;
200         return kip->insns;
201 }
202
203 kprobe_opcode_t __kprobes *get_insn_slot(void)
204 {
205         kprobe_opcode_t *ret;
206         mutex_lock(&kprobe_insn_mutex);
207         ret = __get_insn_slot();
208         mutex_unlock(&kprobe_insn_mutex);
209         return ret;
210 }
211
212 /* Return 1 if all garbages are collected, otherwise 0. */
213 static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
214 {
215         kip->slot_used[idx] = SLOT_CLEAN;
216         kip->nused--;
217         if (kip->nused == 0) {
218                 /*
219                  * Page is no longer in use.  Free it unless
220                  * it's the last one.  We keep the last one
221                  * so as not to have to set it up again the
222                  * next time somebody inserts a probe.
223                  */
224                 if (!list_is_singular(&kprobe_insn_pages)) {
225                         list_del(&kip->list);
226                         module_free(NULL, kip->insns);
227                         kfree(kip);
228                 }
229                 return 1;
230         }
231         return 0;
232 }
233
234 static int __kprobes collect_garbage_slots(void)
235 {
236         struct kprobe_insn_page *kip, *next;
237
238         /* Ensure no-one is preepmted on the garbages */
239         if (check_safety())
240                 return -EAGAIN;
241
242         list_for_each_entry_safe(kip, next, &kprobe_insn_pages, list) {
243                 int i;
244                 if (kip->ngarbage == 0)
245                         continue;
246                 kip->ngarbage = 0;      /* we will collect all garbages */
247                 for (i = 0; i < INSNS_PER_PAGE; i++) {
248                         if (kip->slot_used[i] == SLOT_DIRTY &&
249                             collect_one_slot(kip, i))
250                                 break;
251                 }
252         }
253         kprobe_garbage_slots = 0;
254         return 0;
255 }
256
257 void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
258 {
259         struct kprobe_insn_page *kip;
260
261         mutex_lock(&kprobe_insn_mutex);
262         list_for_each_entry(kip, &kprobe_insn_pages, list) {
263                 if (kip->insns <= slot &&
264                     slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) {
265                         int i = (slot - kip->insns) / MAX_INSN_SIZE;
266                         if (dirty) {
267                                 kip->slot_used[i] = SLOT_DIRTY;
268                                 kip->ngarbage++;
269                         } else
270                                 collect_one_slot(kip, i);
271                         break;
272                 }
273         }
274
275         if (dirty && ++kprobe_garbage_slots > INSNS_PER_PAGE)
276                 collect_garbage_slots();
277
278         mutex_unlock(&kprobe_insn_mutex);
279 }
280 #endif
281
282 /* We have preemption disabled.. so it is safe to use __ versions */
283 static inline void set_kprobe_instance(struct kprobe *kp)
284 {
285         __get_cpu_var(kprobe_instance) = kp;
286 }
287
288 static inline void reset_kprobe_instance(void)
289 {
290         __get_cpu_var(kprobe_instance) = NULL;
291 }
292
293 /*
294  * This routine is called either:
295  *      - under the kprobe_mutex - during kprobe_[un]register()
296  *                              OR
297  *      - with preemption disabled - from arch/xxx/kernel/kprobes.c
298  */
299 struct kprobe __kprobes *get_kprobe(void *addr)
300 {
301         struct hlist_head *head;
302         struct hlist_node *node;
303         struct kprobe *p;
304
305         head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
306         hlist_for_each_entry_rcu(p, node, head, hlist) {
307                 if (p->addr == addr)
308                         return p;
309         }
310         return NULL;
311 }
312
313 /* Arm a kprobe with text_mutex */
314 static void __kprobes arm_kprobe(struct kprobe *kp)
315 {
316         mutex_lock(&text_mutex);
317         arch_arm_kprobe(kp);
318         mutex_unlock(&text_mutex);
319 }
320
321 /* Disarm a kprobe with text_mutex */
322 static void __kprobes disarm_kprobe(struct kprobe *kp)
323 {
324         mutex_lock(&text_mutex);
325         arch_disarm_kprobe(kp);
326         mutex_unlock(&text_mutex);
327 }
328
329 /*
330  * Aggregate handlers for multiple kprobes support - these handlers
331  * take care of invoking the individual kprobe handlers on p->list
332  */
333 static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
334 {
335         struct kprobe *kp;
336
337         list_for_each_entry_rcu(kp, &p->list, list) {
338                 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
339                         set_kprobe_instance(kp);
340                         if (kp->pre_handler(kp, regs))
341                                 return 1;
342                 }
343                 reset_kprobe_instance();
344         }
345         return 0;
346 }
347
348 static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
349                                         unsigned long flags)
350 {
351         struct kprobe *kp;
352
353         list_for_each_entry_rcu(kp, &p->list, list) {
354                 if (kp->post_handler && likely(!kprobe_disabled(kp))) {
355                         set_kprobe_instance(kp);
356                         kp->post_handler(kp, regs, flags);
357                         reset_kprobe_instance();
358                 }
359         }
360 }
361
362 static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
363                                         int trapnr)
364 {
365         struct kprobe *cur = __get_cpu_var(kprobe_instance);
366
367         /*
368          * if we faulted "during" the execution of a user specified
369          * probe handler, invoke just that probe's fault handler
370          */
371         if (cur && cur->fault_handler) {
372                 if (cur->fault_handler(cur, regs, trapnr))
373                         return 1;
374         }
375         return 0;
376 }
377
378 static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
379 {
380         struct kprobe *cur = __get_cpu_var(kprobe_instance);
381         int ret = 0;
382
383         if (cur && cur->break_handler) {
384                 if (cur->break_handler(cur, regs))
385                         ret = 1;
386         }
387         reset_kprobe_instance();
388         return ret;
389 }
390
391 /* Walks the list and increments nmissed count for multiprobe case */
392 void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
393 {
394         struct kprobe *kp;
395         if (p->pre_handler != aggr_pre_handler) {
396                 p->nmissed++;
397         } else {
398                 list_for_each_entry_rcu(kp, &p->list, list)
399                         kp->nmissed++;
400         }
401         return;
402 }
403
404 void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
405                                 struct hlist_head *head)
406 {
407         struct kretprobe *rp = ri->rp;
408
409         /* remove rp inst off the rprobe_inst_table */
410         hlist_del(&ri->hlist);
411         INIT_HLIST_NODE(&ri->hlist);
412         if (likely(rp)) {
413                 spin_lock(&rp->lock);
414                 hlist_add_head(&ri->hlist, &rp->free_instances);
415                 spin_unlock(&rp->lock);
416         } else
417                 /* Unregistering */
418                 hlist_add_head(&ri->hlist, head);
419 }
420
421 void __kprobes kretprobe_hash_lock(struct task_struct *tsk,
422                          struct hlist_head **head, unsigned long *flags)
423 {
424         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
425         spinlock_t *hlist_lock;
426
427         *head = &kretprobe_inst_table[hash];
428         hlist_lock = kretprobe_table_lock_ptr(hash);
429         spin_lock_irqsave(hlist_lock, *flags);
430 }
431
432 static void __kprobes kretprobe_table_lock(unsigned long hash,
433         unsigned long *flags)
434 {
435         spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
436         spin_lock_irqsave(hlist_lock, *flags);
437 }
438
439 void __kprobes kretprobe_hash_unlock(struct task_struct *tsk,
440         unsigned long *flags)
441 {
442         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
443         spinlock_t *hlist_lock;
444
445         hlist_lock = kretprobe_table_lock_ptr(hash);
446         spin_unlock_irqrestore(hlist_lock, *flags);
447 }
448
449 void __kprobes kretprobe_table_unlock(unsigned long hash, unsigned long *flags)
450 {
451         spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
452         spin_unlock_irqrestore(hlist_lock, *flags);
453 }
454
455 /*
456  * This function is called from finish_task_switch when task tk becomes dead,
457  * so that we can recycle any function-return probe instances associated
458  * with this task. These left over instances represent probed functions
459  * that have been called but will never return.
460  */
461 void __kprobes kprobe_flush_task(struct task_struct *tk)
462 {
463         struct kretprobe_instance *ri;
464         struct hlist_head *head, empty_rp;
465         struct hlist_node *node, *tmp;
466         unsigned long hash, flags = 0;
467
468         if (unlikely(!kprobes_initialized))
469                 /* Early boot.  kretprobe_table_locks not yet initialized. */
470                 return;
471
472         hash = hash_ptr(tk, KPROBE_HASH_BITS);
473         head = &kretprobe_inst_table[hash];
474         kretprobe_table_lock(hash, &flags);
475         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
476                 if (ri->task == tk)
477                         recycle_rp_inst(ri, &empty_rp);
478         }
479         kretprobe_table_unlock(hash, &flags);
480         INIT_HLIST_HEAD(&empty_rp);
481         hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
482                 hlist_del(&ri->hlist);
483                 kfree(ri);
484         }
485 }
486
487 static inline void free_rp_inst(struct kretprobe *rp)
488 {
489         struct kretprobe_instance *ri;
490         struct hlist_node *pos, *next;
491
492         hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, hlist) {
493                 hlist_del(&ri->hlist);
494                 kfree(ri);
495         }
496 }
497
498 static void __kprobes cleanup_rp_inst(struct kretprobe *rp)
499 {
500         unsigned long flags, hash;
501         struct kretprobe_instance *ri;
502         struct hlist_node *pos, *next;
503         struct hlist_head *head;
504
505         /* No race here */
506         for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
507                 kretprobe_table_lock(hash, &flags);
508                 head = &kretprobe_inst_table[hash];
509                 hlist_for_each_entry_safe(ri, pos, next, head, hlist) {
510                         if (ri->rp == rp)
511                                 ri->rp = NULL;
512                 }
513                 kretprobe_table_unlock(hash, &flags);
514         }
515         free_rp_inst(rp);
516 }
517
518 /*
519  * Keep all fields in the kprobe consistent
520  */
521 static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p)
522 {
523         memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t));
524         memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn));
525 }
526
527 /*
528 * Add the new probe to ap->list. Fail if this is the
529 * second jprobe at the address - two jprobes can't coexist
530 */
531 static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p)
532 {
533         BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
534         if (p->break_handler) {
535                 if (ap->break_handler)
536                         return -EEXIST;
537                 list_add_tail_rcu(&p->list, &ap->list);
538                 ap->break_handler = aggr_break_handler;
539         } else
540                 list_add_rcu(&p->list, &ap->list);
541         if (p->post_handler && !ap->post_handler)
542                 ap->post_handler = aggr_post_handler;
543
544         if (kprobe_disabled(ap) && !kprobe_disabled(p)) {
545                 ap->flags &= ~KPROBE_FLAG_DISABLED;
546                 if (!kprobes_all_disarmed)
547                         /* Arm the breakpoint again. */
548                         arm_kprobe(ap);
549         }
550         return 0;
551 }
552
553 /*
554  * Fill in the required fields of the "manager kprobe". Replace the
555  * earlier kprobe in the hlist with the manager kprobe
556  */
557 static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
558 {
559         copy_kprobe(p, ap);
560         flush_insn_slot(ap);
561         ap->addr = p->addr;
562         ap->flags = p->flags;
563         ap->pre_handler = aggr_pre_handler;
564         ap->fault_handler = aggr_fault_handler;
565         /* We don't care the kprobe which has gone. */
566         if (p->post_handler && !kprobe_gone(p))
567                 ap->post_handler = aggr_post_handler;
568         if (p->break_handler && !kprobe_gone(p))
569                 ap->break_handler = aggr_break_handler;
570
571         INIT_LIST_HEAD(&ap->list);
572         list_add_rcu(&p->list, &ap->list);
573
574         hlist_replace_rcu(&p->hlist, &ap->hlist);
575 }
576
577 /*
578  * This is the second or subsequent kprobe at the address - handle
579  * the intricacies
580  */
581 static int __kprobes register_aggr_kprobe(struct kprobe *old_p,
582                                           struct kprobe *p)
583 {
584         int ret = 0;
585         struct kprobe *ap = old_p;
586
587         if (old_p->pre_handler != aggr_pre_handler) {
588                 /* If old_p is not an aggr_probe, create new aggr_kprobe. */
589                 ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL);
590                 if (!ap)
591                         return -ENOMEM;
592                 add_aggr_kprobe(ap, old_p);
593         }
594
595         if (kprobe_gone(ap)) {
596                 /*
597                  * Attempting to insert new probe at the same location that
598                  * had a probe in the module vaddr area which already
599                  * freed. So, the instruction slot has already been
600                  * released. We need a new slot for the new probe.
601                  */
602                 ret = arch_prepare_kprobe(ap);
603                 if (ret)
604                         /*
605                          * Even if fail to allocate new slot, don't need to
606                          * free aggr_probe. It will be used next time, or
607                          * freed by unregister_kprobe.
608                          */
609                         return ret;
610
611                 /*
612                  * Clear gone flag to prevent allocating new slot again, and
613                  * set disabled flag because it is not armed yet.
614                  */
615                 ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
616                             | KPROBE_FLAG_DISABLED;
617         }
618
619         copy_kprobe(ap, p);
620         return add_new_kprobe(ap, p);
621 }
622
623 /* Try to disable aggr_kprobe, and return 1 if succeeded.*/
624 static int __kprobes try_to_disable_aggr_kprobe(struct kprobe *p)
625 {
626         struct kprobe *kp;
627
628         list_for_each_entry_rcu(kp, &p->list, list) {
629                 if (!kprobe_disabled(kp))
630                         /*
631                          * There is an active probe on the list.
632                          * We can't disable aggr_kprobe.
633                          */
634                         return 0;
635         }
636         p->flags |= KPROBE_FLAG_DISABLED;
637         return 1;
638 }
639
640 static int __kprobes in_kprobes_functions(unsigned long addr)
641 {
642         struct kprobe_blackpoint *kb;
643
644         if (addr >= (unsigned long)__kprobes_text_start &&
645             addr < (unsigned long)__kprobes_text_end)
646                 return -EINVAL;
647         /*
648          * If there exists a kprobe_blacklist, verify and
649          * fail any probe registration in the prohibited area
650          */
651         for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
652                 if (kb->start_addr) {
653                         if (addr >= kb->start_addr &&
654                             addr < (kb->start_addr + kb->range))
655                                 return -EINVAL;
656                 }
657         }
658         return 0;
659 }
660
661 /*
662  * If we have a symbol_name argument, look it up and add the offset field
663  * to it. This way, we can specify a relative address to a symbol.
664  */
665 static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p)
666 {
667         kprobe_opcode_t *addr = p->addr;
668         if (p->symbol_name) {
669                 if (addr)
670                         return NULL;
671                 kprobe_lookup_name(p->symbol_name, addr);
672         }
673
674         if (!addr)
675                 return NULL;
676         return (kprobe_opcode_t *)(((char *)addr) + p->offset);
677 }
678
679 int __kprobes register_kprobe(struct kprobe *p)
680 {
681         int ret = 0;
682         struct kprobe *old_p;
683         struct module *probed_mod;
684         kprobe_opcode_t *addr;
685
686         addr = kprobe_addr(p);
687         if (!addr)
688                 return -EINVAL;
689         p->addr = addr;
690
691         preempt_disable();
692         if (!kernel_text_address((unsigned long) p->addr) ||
693             in_kprobes_functions((unsigned long) p->addr)) {
694                 preempt_enable();
695                 return -EINVAL;
696         }
697
698         /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
699         p->flags &= KPROBE_FLAG_DISABLED;
700
701         /*
702          * Check if are we probing a module.
703          */
704         probed_mod = __module_text_address((unsigned long) p->addr);
705         if (probed_mod) {
706                 /*
707                  * We must hold a refcount of the probed module while updating
708                  * its code to prohibit unexpected unloading.
709                  */
710                 if (unlikely(!try_module_get(probed_mod))) {
711                         preempt_enable();
712                         return -EINVAL;
713                 }
714                 /*
715                  * If the module freed .init.text, we couldn't insert
716                  * kprobes in there.
717                  */
718                 if (within_module_init((unsigned long)p->addr, probed_mod) &&
719                     probed_mod->state != MODULE_STATE_COMING) {
720                         module_put(probed_mod);
721                         preempt_enable();
722                         return -EINVAL;
723                 }
724         }
725         preempt_enable();
726
727         p->nmissed = 0;
728         INIT_LIST_HEAD(&p->list);
729         mutex_lock(&kprobe_mutex);
730         old_p = get_kprobe(p->addr);
731         if (old_p) {
732                 ret = register_aggr_kprobe(old_p, p);
733                 goto out;
734         }
735
736         mutex_lock(&text_mutex);
737         ret = arch_prepare_kprobe(p);
738         if (ret)
739                 goto out_unlock_text;
740
741         INIT_HLIST_NODE(&p->hlist);
742         hlist_add_head_rcu(&p->hlist,
743                        &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
744
745         if (!kprobes_all_disarmed && !kprobe_disabled(p))
746                 arch_arm_kprobe(p);
747
748 out_unlock_text:
749         mutex_unlock(&text_mutex);
750 out:
751         mutex_unlock(&kprobe_mutex);
752
753         if (probed_mod)
754                 module_put(probed_mod);
755
756         return ret;
757 }
758 EXPORT_SYMBOL_GPL(register_kprobe);
759
760 /* Check passed kprobe is valid and return kprobe in kprobe_table. */
761 static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p)
762 {
763         struct kprobe *old_p, *list_p;
764
765         old_p = get_kprobe(p->addr);
766         if (unlikely(!old_p))
767                 return NULL;
768
769         if (p != old_p) {
770                 list_for_each_entry_rcu(list_p, &old_p->list, list)
771                         if (list_p == p)
772                         /* kprobe p is a valid probe */
773                                 goto valid;
774                 return NULL;
775         }
776 valid:
777         return old_p;
778 }
779
780 /*
781  * Unregister a kprobe without a scheduler synchronization.
782  */
783 static int __kprobes __unregister_kprobe_top(struct kprobe *p)
784 {
785         struct kprobe *old_p, *list_p;
786
787         old_p = __get_valid_kprobe(p);
788         if (old_p == NULL)
789                 return -EINVAL;
790
791         if (old_p == p ||
792             (old_p->pre_handler == aggr_pre_handler &&
793              list_is_singular(&old_p->list))) {
794                 /*
795                  * Only probe on the hash list. Disarm only if kprobes are
796                  * enabled and not gone - otherwise, the breakpoint would
797                  * already have been removed. We save on flushing icache.
798                  */
799                 if (!kprobes_all_disarmed && !kprobe_disabled(old_p))
800                         disarm_kprobe(p);
801                 hlist_del_rcu(&old_p->hlist);
802         } else {
803                 if (p->break_handler && !kprobe_gone(p))
804                         old_p->break_handler = NULL;
805                 if (p->post_handler && !kprobe_gone(p)) {
806                         list_for_each_entry_rcu(list_p, &old_p->list, list) {
807                                 if ((list_p != p) && (list_p->post_handler))
808                                         goto noclean;
809                         }
810                         old_p->post_handler = NULL;
811                 }
812 noclean:
813                 list_del_rcu(&p->list);
814                 if (!kprobe_disabled(old_p)) {
815                         try_to_disable_aggr_kprobe(old_p);
816                         if (!kprobes_all_disarmed && kprobe_disabled(old_p))
817                                 disarm_kprobe(old_p);
818                 }
819         }
820         return 0;
821 }
822
823 static void __kprobes __unregister_kprobe_bottom(struct kprobe *p)
824 {
825         struct kprobe *old_p;
826
827         if (list_empty(&p->list))
828                 arch_remove_kprobe(p);
829         else if (list_is_singular(&p->list)) {
830                 /* "p" is the last child of an aggr_kprobe */
831                 old_p = list_entry(p->list.next, struct kprobe, list);
832                 list_del(&p->list);
833                 arch_remove_kprobe(old_p);
834                 kfree(old_p);
835         }
836 }
837
838 int __kprobes register_kprobes(struct kprobe **kps, int num)
839 {
840         int i, ret = 0;
841
842         if (num <= 0)
843                 return -EINVAL;
844         for (i = 0; i < num; i++) {
845                 ret = register_kprobe(kps[i]);
846                 if (ret < 0) {
847                         if (i > 0)
848                                 unregister_kprobes(kps, i);
849                         break;
850                 }
851         }
852         return ret;
853 }
854 EXPORT_SYMBOL_GPL(register_kprobes);
855
856 void __kprobes unregister_kprobe(struct kprobe *p)
857 {
858         unregister_kprobes(&p, 1);
859 }
860 EXPORT_SYMBOL_GPL(unregister_kprobe);
861
862 void __kprobes unregister_kprobes(struct kprobe **kps, int num)
863 {
864         int i;
865
866         if (num <= 0)
867                 return;
868         mutex_lock(&kprobe_mutex);
869         for (i = 0; i < num; i++)
870                 if (__unregister_kprobe_top(kps[i]) < 0)
871                         kps[i]->addr = NULL;
872         mutex_unlock(&kprobe_mutex);
873
874         synchronize_sched();
875         for (i = 0; i < num; i++)
876                 if (kps[i]->addr)
877                         __unregister_kprobe_bottom(kps[i]);
878 }
879 EXPORT_SYMBOL_GPL(unregister_kprobes);
880
881 static struct notifier_block kprobe_exceptions_nb = {
882         .notifier_call = kprobe_exceptions_notify,
883         .priority = 0x7fffffff /* we need to be notified first */
884 };
885
886 unsigned long __weak arch_deref_entry_point(void *entry)
887 {
888         return (unsigned long)entry;
889 }
890
891 int __kprobes register_jprobes(struct jprobe **jps, int num)
892 {
893         struct jprobe *jp;
894         int ret = 0, i;
895
896         if (num <= 0)
897                 return -EINVAL;
898         for (i = 0; i < num; i++) {
899                 unsigned long addr;
900                 jp = jps[i];
901                 addr = arch_deref_entry_point(jp->entry);
902
903                 if (!kernel_text_address(addr))
904                         ret = -EINVAL;
905                 else {
906                         /* Todo: Verify probepoint is a function entry point */
907                         jp->kp.pre_handler = setjmp_pre_handler;
908                         jp->kp.break_handler = longjmp_break_handler;
909                         ret = register_kprobe(&jp->kp);
910                 }
911                 if (ret < 0) {
912                         if (i > 0)
913                                 unregister_jprobes(jps, i);
914                         break;
915                 }
916         }
917         return ret;
918 }
919 EXPORT_SYMBOL_GPL(register_jprobes);
920
921 int __kprobes register_jprobe(struct jprobe *jp)
922 {
923         return register_jprobes(&jp, 1);
924 }
925 EXPORT_SYMBOL_GPL(register_jprobe);
926
927 void __kprobes unregister_jprobe(struct jprobe *jp)
928 {
929         unregister_jprobes(&jp, 1);
930 }
931 EXPORT_SYMBOL_GPL(unregister_jprobe);
932
933 void __kprobes unregister_jprobes(struct jprobe **jps, int num)
934 {
935         int i;
936
937         if (num <= 0)
938                 return;
939         mutex_lock(&kprobe_mutex);
940         for (i = 0; i < num; i++)
941                 if (__unregister_kprobe_top(&jps[i]->kp) < 0)
942                         jps[i]->kp.addr = NULL;
943         mutex_unlock(&kprobe_mutex);
944
945         synchronize_sched();
946         for (i = 0; i < num; i++) {
947                 if (jps[i]->kp.addr)
948                         __unregister_kprobe_bottom(&jps[i]->kp);
949         }
950 }
951 EXPORT_SYMBOL_GPL(unregister_jprobes);
952
953 #ifdef CONFIG_KRETPROBES
954 /*
955  * This kprobe pre_handler is registered with every kretprobe. When probe
956  * hits it will set up the return probe.
957  */
958 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
959                                            struct pt_regs *regs)
960 {
961         struct kretprobe *rp = container_of(p, struct kretprobe, kp);
962         unsigned long hash, flags = 0;
963         struct kretprobe_instance *ri;
964
965         /*TODO: consider to only swap the RA after the last pre_handler fired */
966         hash = hash_ptr(current, KPROBE_HASH_BITS);
967         spin_lock_irqsave(&rp->lock, flags);
968         if (!hlist_empty(&rp->free_instances)) {
969                 ri = hlist_entry(rp->free_instances.first,
970                                 struct kretprobe_instance, hlist);
971                 hlist_del(&ri->hlist);
972                 spin_unlock_irqrestore(&rp->lock, flags);
973
974                 ri->rp = rp;
975                 ri->task = current;
976
977                 if (rp->entry_handler && rp->entry_handler(ri, regs))
978                         return 0;
979
980                 arch_prepare_kretprobe(ri, regs);
981
982                 /* XXX(hch): why is there no hlist_move_head? */
983                 INIT_HLIST_NODE(&ri->hlist);
984                 kretprobe_table_lock(hash, &flags);
985                 hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
986                 kretprobe_table_unlock(hash, &flags);
987         } else {
988                 rp->nmissed++;
989                 spin_unlock_irqrestore(&rp->lock, flags);
990         }
991         return 0;
992 }
993
994 int __kprobes register_kretprobe(struct kretprobe *rp)
995 {
996         int ret = 0;
997         struct kretprobe_instance *inst;
998         int i;
999         void *addr;
1000
1001         if (kretprobe_blacklist_size) {
1002                 addr = kprobe_addr(&rp->kp);
1003                 if (!addr)
1004                         return -EINVAL;
1005
1006                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1007                         if (kretprobe_blacklist[i].addr == addr)
1008                                 return -EINVAL;
1009                 }
1010         }
1011
1012         rp->kp.pre_handler = pre_handler_kretprobe;
1013         rp->kp.post_handler = NULL;
1014         rp->kp.fault_handler = NULL;
1015         rp->kp.break_handler = NULL;
1016
1017         /* Pre-allocate memory for max kretprobe instances */
1018         if (rp->maxactive <= 0) {
1019 #ifdef CONFIG_PREEMPT
1020                 rp->maxactive = max(10, 2 * NR_CPUS);
1021 #else
1022                 rp->maxactive = NR_CPUS;
1023 #endif
1024         }
1025         spin_lock_init(&rp->lock);
1026         INIT_HLIST_HEAD(&rp->free_instances);
1027         for (i = 0; i < rp->maxactive; i++) {
1028                 inst = kmalloc(sizeof(struct kretprobe_instance) +
1029                                rp->data_size, GFP_KERNEL);
1030                 if (inst == NULL) {
1031                         free_rp_inst(rp);
1032                         return -ENOMEM;
1033                 }
1034                 INIT_HLIST_NODE(&inst->hlist);
1035                 hlist_add_head(&inst->hlist, &rp->free_instances);
1036         }
1037
1038         rp->nmissed = 0;
1039         /* Establish function entry probe point */
1040         ret = register_kprobe(&rp->kp);
1041         if (ret != 0)
1042                 free_rp_inst(rp);
1043         return ret;
1044 }
1045 EXPORT_SYMBOL_GPL(register_kretprobe);
1046
1047 int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1048 {
1049         int ret = 0, i;
1050
1051         if (num <= 0)
1052                 return -EINVAL;
1053         for (i = 0; i < num; i++) {
1054                 ret = register_kretprobe(rps[i]);
1055                 if (ret < 0) {
1056                         if (i > 0)
1057                                 unregister_kretprobes(rps, i);
1058                         break;
1059                 }
1060         }
1061         return ret;
1062 }
1063 EXPORT_SYMBOL_GPL(register_kretprobes);
1064
1065 void __kprobes unregister_kretprobe(struct kretprobe *rp)
1066 {
1067         unregister_kretprobes(&rp, 1);
1068 }
1069 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1070
1071 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1072 {
1073         int i;
1074
1075         if (num <= 0)
1076                 return;
1077         mutex_lock(&kprobe_mutex);
1078         for (i = 0; i < num; i++)
1079                 if (__unregister_kprobe_top(&rps[i]->kp) < 0)
1080                         rps[i]->kp.addr = NULL;
1081         mutex_unlock(&kprobe_mutex);
1082
1083         synchronize_sched();
1084         for (i = 0; i < num; i++) {
1085                 if (rps[i]->kp.addr) {
1086                         __unregister_kprobe_bottom(&rps[i]->kp);
1087                         cleanup_rp_inst(rps[i]);
1088                 }
1089         }
1090 }
1091 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1092
1093 #else /* CONFIG_KRETPROBES */
1094 int __kprobes register_kretprobe(struct kretprobe *rp)
1095 {
1096         return -ENOSYS;
1097 }
1098 EXPORT_SYMBOL_GPL(register_kretprobe);
1099
1100 int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1101 {
1102         return -ENOSYS;
1103 }
1104 EXPORT_SYMBOL_GPL(register_kretprobes);
1105
1106 void __kprobes unregister_kretprobe(struct kretprobe *rp)
1107 {
1108 }
1109 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1110
1111 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1112 {
1113 }
1114 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1115
1116 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
1117                                            struct pt_regs *regs)
1118 {
1119         return 0;
1120 }
1121
1122 #endif /* CONFIG_KRETPROBES */
1123
1124 /* Set the kprobe gone and remove its instruction buffer. */
1125 static void __kprobes kill_kprobe(struct kprobe *p)
1126 {
1127         struct kprobe *kp;
1128
1129         p->flags |= KPROBE_FLAG_GONE;
1130         if (p->pre_handler == aggr_pre_handler) {
1131                 /*
1132                  * If this is an aggr_kprobe, we have to list all the
1133                  * chained probes and mark them GONE.
1134                  */
1135                 list_for_each_entry_rcu(kp, &p->list, list)
1136                         kp->flags |= KPROBE_FLAG_GONE;
1137                 p->post_handler = NULL;
1138                 p->break_handler = NULL;
1139         }
1140         /*
1141          * Here, we can remove insn_slot safely, because no thread calls
1142          * the original probed function (which will be freed soon) any more.
1143          */
1144         arch_remove_kprobe(p);
1145 }
1146
1147 void __kprobes dump_kprobe(struct kprobe *kp)
1148 {
1149         printk(KERN_WARNING "Dumping kprobe:\n");
1150         printk(KERN_WARNING "Name: %s\nAddress: %p\nOffset: %x\n",
1151                kp->symbol_name, kp->addr, kp->offset);
1152 }
1153
1154 /* Module notifier call back, checking kprobes on the module */
1155 static int __kprobes kprobes_module_callback(struct notifier_block *nb,
1156                                              unsigned long val, void *data)
1157 {
1158         struct module *mod = data;
1159         struct hlist_head *head;
1160         struct hlist_node *node;
1161         struct kprobe *p;
1162         unsigned int i;
1163         int checkcore = (val == MODULE_STATE_GOING);
1164
1165         if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
1166                 return NOTIFY_DONE;
1167
1168         /*
1169          * When MODULE_STATE_GOING was notified, both of module .text and
1170          * .init.text sections would be freed. When MODULE_STATE_LIVE was
1171          * notified, only .init.text section would be freed. We need to
1172          * disable kprobes which have been inserted in the sections.
1173          */
1174         mutex_lock(&kprobe_mutex);
1175         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1176                 head = &kprobe_table[i];
1177                 hlist_for_each_entry_rcu(p, node, head, hlist)
1178                         if (within_module_init((unsigned long)p->addr, mod) ||
1179                             (checkcore &&
1180                              within_module_core((unsigned long)p->addr, mod))) {
1181                                 /*
1182                                  * The vaddr this probe is installed will soon
1183                                  * be vfreed buy not synced to disk. Hence,
1184                                  * disarming the breakpoint isn't needed.
1185                                  */
1186                                 kill_kprobe(p);
1187                         }
1188         }
1189         mutex_unlock(&kprobe_mutex);
1190         return NOTIFY_DONE;
1191 }
1192
1193 static struct notifier_block kprobe_module_nb = {
1194         .notifier_call = kprobes_module_callback,
1195         .priority = 0
1196 };
1197
1198 static int __init init_kprobes(void)
1199 {
1200         int i, err = 0;
1201         unsigned long offset = 0, size = 0;
1202         char *modname, namebuf[128];
1203         const char *symbol_name;
1204         void *addr;
1205         struct kprobe_blackpoint *kb;
1206
1207         /* FIXME allocate the probe table, currently defined statically */
1208         /* initialize all list heads */
1209         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1210                 INIT_HLIST_HEAD(&kprobe_table[i]);
1211                 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
1212                 spin_lock_init(&(kretprobe_table_locks[i].lock));
1213         }
1214
1215         /*
1216          * Lookup and populate the kprobe_blacklist.
1217          *
1218          * Unlike the kretprobe blacklist, we'll need to determine
1219          * the range of addresses that belong to the said functions,
1220          * since a kprobe need not necessarily be at the beginning
1221          * of a function.
1222          */
1223         for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
1224                 kprobe_lookup_name(kb->name, addr);
1225                 if (!addr)
1226                         continue;
1227
1228                 kb->start_addr = (unsigned long)addr;
1229                 symbol_name = kallsyms_lookup(kb->start_addr,
1230                                 &size, &offset, &modname, namebuf);
1231                 if (!symbol_name)
1232                         kb->range = 0;
1233                 else
1234                         kb->range = size;
1235         }
1236
1237         if (kretprobe_blacklist_size) {
1238                 /* lookup the function address from its name */
1239                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1240                         kprobe_lookup_name(kretprobe_blacklist[i].name,
1241                                            kretprobe_blacklist[i].addr);
1242                         if (!kretprobe_blacklist[i].addr)
1243                                 printk("kretprobe: lookup failed: %s\n",
1244                                        kretprobe_blacklist[i].name);
1245                 }
1246         }
1247
1248         /* By default, kprobes are armed */
1249         kprobes_all_disarmed = false;
1250
1251         err = arch_init_kprobes();
1252         if (!err)
1253                 err = register_die_notifier(&kprobe_exceptions_nb);
1254         if (!err)
1255                 err = register_module_notifier(&kprobe_module_nb);
1256
1257         kprobes_initialized = (err == 0);
1258
1259         if (!err)
1260                 init_test_probes();
1261         return err;
1262 }
1263
1264 #ifdef CONFIG_DEBUG_FS
1265 static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
1266                 const char *sym, int offset,char *modname)
1267 {
1268         char *kprobe_type;
1269
1270         if (p->pre_handler == pre_handler_kretprobe)
1271                 kprobe_type = "r";
1272         else if (p->pre_handler == setjmp_pre_handler)
1273                 kprobe_type = "j";
1274         else
1275                 kprobe_type = "k";
1276         if (sym)
1277                 seq_printf(pi, "%p  %s  %s+0x%x  %s %s%s\n",
1278                         p->addr, kprobe_type, sym, offset,
1279                         (modname ? modname : " "),
1280                         (kprobe_gone(p) ? "[GONE]" : ""),
1281                         ((kprobe_disabled(p) && !kprobe_gone(p)) ?
1282                          "[DISABLED]" : ""));
1283         else
1284                 seq_printf(pi, "%p  %s  %p %s%s\n",
1285                         p->addr, kprobe_type, p->addr,
1286                         (kprobe_gone(p) ? "[GONE]" : ""),
1287                         ((kprobe_disabled(p) && !kprobe_gone(p)) ?
1288                          "[DISABLED]" : ""));
1289 }
1290
1291 static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
1292 {
1293         return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
1294 }
1295
1296 static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
1297 {
1298         (*pos)++;
1299         if (*pos >= KPROBE_TABLE_SIZE)
1300                 return NULL;
1301         return pos;
1302 }
1303
1304 static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v)
1305 {
1306         /* Nothing to do */
1307 }
1308
1309 static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v)
1310 {
1311         struct hlist_head *head;
1312         struct hlist_node *node;
1313         struct kprobe *p, *kp;
1314         const char *sym = NULL;
1315         unsigned int i = *(loff_t *) v;
1316         unsigned long offset = 0;
1317         char *modname, namebuf[128];
1318
1319         head = &kprobe_table[i];
1320         preempt_disable();
1321         hlist_for_each_entry_rcu(p, node, head, hlist) {
1322                 sym = kallsyms_lookup((unsigned long)p->addr, NULL,
1323                                         &offset, &modname, namebuf);
1324                 if (p->pre_handler == aggr_pre_handler) {
1325                         list_for_each_entry_rcu(kp, &p->list, list)
1326                                 report_probe(pi, kp, sym, offset, modname);
1327                 } else
1328                         report_probe(pi, p, sym, offset, modname);
1329         }
1330         preempt_enable();
1331         return 0;
1332 }
1333
1334 static struct seq_operations kprobes_seq_ops = {
1335         .start = kprobe_seq_start,
1336         .next  = kprobe_seq_next,
1337         .stop  = kprobe_seq_stop,
1338         .show  = show_kprobe_addr
1339 };
1340
1341 static int __kprobes kprobes_open(struct inode *inode, struct file *filp)
1342 {
1343         return seq_open(filp, &kprobes_seq_ops);
1344 }
1345
1346 static struct file_operations debugfs_kprobes_operations = {
1347         .open           = kprobes_open,
1348         .read           = seq_read,
1349         .llseek         = seq_lseek,
1350         .release        = seq_release,
1351 };
1352
1353 /* Disable one kprobe */
1354 int __kprobes disable_kprobe(struct kprobe *kp)
1355 {
1356         int ret = 0;
1357         struct kprobe *p;
1358
1359         mutex_lock(&kprobe_mutex);
1360
1361         /* Check whether specified probe is valid. */
1362         p = __get_valid_kprobe(kp);
1363         if (unlikely(p == NULL)) {
1364                 ret = -EINVAL;
1365                 goto out;
1366         }
1367
1368         /* If the probe is already disabled (or gone), just return */
1369         if (kprobe_disabled(kp))
1370                 goto out;
1371
1372         kp->flags |= KPROBE_FLAG_DISABLED;
1373         if (p != kp)
1374                 /* When kp != p, p is always enabled. */
1375                 try_to_disable_aggr_kprobe(p);
1376
1377         if (!kprobes_all_disarmed && kprobe_disabled(p))
1378                 disarm_kprobe(p);
1379 out:
1380         mutex_unlock(&kprobe_mutex);
1381         return ret;
1382 }
1383 EXPORT_SYMBOL_GPL(disable_kprobe);
1384
1385 /* Enable one kprobe */
1386 int __kprobes enable_kprobe(struct kprobe *kp)
1387 {
1388         int ret = 0;
1389         struct kprobe *p;
1390
1391         mutex_lock(&kprobe_mutex);
1392
1393         /* Check whether specified probe is valid. */
1394         p = __get_valid_kprobe(kp);
1395         if (unlikely(p == NULL)) {
1396                 ret = -EINVAL;
1397                 goto out;
1398         }
1399
1400         if (kprobe_gone(kp)) {
1401                 /* This kprobe has gone, we couldn't enable it. */
1402                 ret = -EINVAL;
1403                 goto out;
1404         }
1405
1406         if (!kprobes_all_disarmed && kprobe_disabled(p))
1407                 arm_kprobe(p);
1408
1409         p->flags &= ~KPROBE_FLAG_DISABLED;
1410         if (p != kp)
1411                 kp->flags &= ~KPROBE_FLAG_DISABLED;
1412 out:
1413         mutex_unlock(&kprobe_mutex);
1414         return ret;
1415 }
1416 EXPORT_SYMBOL_GPL(enable_kprobe);
1417
1418 static void __kprobes arm_all_kprobes(void)
1419 {
1420         struct hlist_head *head;
1421         struct hlist_node *node;
1422         struct kprobe *p;
1423         unsigned int i;
1424
1425         mutex_lock(&kprobe_mutex);
1426
1427         /* If kprobes are armed, just return */
1428         if (!kprobes_all_disarmed)
1429                 goto already_enabled;
1430
1431         mutex_lock(&text_mutex);
1432         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1433                 head = &kprobe_table[i];
1434                 hlist_for_each_entry_rcu(p, node, head, hlist)
1435                         if (!kprobe_disabled(p))
1436                                 arch_arm_kprobe(p);
1437         }
1438         mutex_unlock(&text_mutex);
1439
1440         kprobes_all_disarmed = false;
1441         printk(KERN_INFO "Kprobes globally enabled\n");
1442
1443 already_enabled:
1444         mutex_unlock(&kprobe_mutex);
1445         return;
1446 }
1447
1448 static void __kprobes disarm_all_kprobes(void)
1449 {
1450         struct hlist_head *head;
1451         struct hlist_node *node;
1452         struct kprobe *p;
1453         unsigned int i;
1454
1455         mutex_lock(&kprobe_mutex);
1456
1457         /* If kprobes are already disarmed, just return */
1458         if (kprobes_all_disarmed)
1459                 goto already_disabled;
1460
1461         kprobes_all_disarmed = true;
1462         printk(KERN_INFO "Kprobes globally disabled\n");
1463         mutex_lock(&text_mutex);
1464         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1465                 head = &kprobe_table[i];
1466                 hlist_for_each_entry_rcu(p, node, head, hlist) {
1467                         if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
1468                                 arch_disarm_kprobe(p);
1469                 }
1470         }
1471
1472         mutex_unlock(&text_mutex);
1473         mutex_unlock(&kprobe_mutex);
1474         /* Allow all currently running kprobes to complete */
1475         synchronize_sched();
1476         return;
1477
1478 already_disabled:
1479         mutex_unlock(&kprobe_mutex);
1480         return;
1481 }
1482
1483 /*
1484  * XXX: The debugfs bool file interface doesn't allow for callbacks
1485  * when the bool state is switched. We can reuse that facility when
1486  * available
1487  */
1488 static ssize_t read_enabled_file_bool(struct file *file,
1489                char __user *user_buf, size_t count, loff_t *ppos)
1490 {
1491         char buf[3];
1492
1493         if (!kprobes_all_disarmed)
1494                 buf[0] = '1';
1495         else
1496                 buf[0] = '0';
1497         buf[1] = '\n';
1498         buf[2] = 0x00;
1499         return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
1500 }
1501
1502 static ssize_t write_enabled_file_bool(struct file *file,
1503                const char __user *user_buf, size_t count, loff_t *ppos)
1504 {
1505         char buf[32];
1506         int buf_size;
1507
1508         buf_size = min(count, (sizeof(buf)-1));
1509         if (copy_from_user(buf, user_buf, buf_size))
1510                 return -EFAULT;
1511
1512         switch (buf[0]) {
1513         case 'y':
1514         case 'Y':
1515         case '1':
1516                 arm_all_kprobes();
1517                 break;
1518         case 'n':
1519         case 'N':
1520         case '0':
1521                 disarm_all_kprobes();
1522                 break;
1523         }
1524
1525         return count;
1526 }
1527
1528 static struct file_operations fops_kp = {
1529         .read =         read_enabled_file_bool,
1530         .write =        write_enabled_file_bool,
1531 };
1532
1533 static int __kprobes debugfs_kprobe_init(void)
1534 {
1535         struct dentry *dir, *file;
1536         unsigned int value = 1;
1537
1538         dir = debugfs_create_dir("kprobes", NULL);
1539         if (!dir)
1540                 return -ENOMEM;
1541
1542         file = debugfs_create_file("list", 0444, dir, NULL,
1543                                 &debugfs_kprobes_operations);
1544         if (!file) {
1545                 debugfs_remove(dir);
1546                 return -ENOMEM;
1547         }
1548
1549         file = debugfs_create_file("enabled", 0600, dir,
1550                                         &value, &fops_kp);
1551         if (!file) {
1552                 debugfs_remove(dir);
1553                 return -ENOMEM;
1554         }
1555
1556         return 0;
1557 }
1558
1559 late_initcall(debugfs_kprobe_init);
1560 #endif /* CONFIG_DEBUG_FS */
1561
1562 module_init(init_kprobes);
1563
1564 /* defined in arch/.../kernel/kprobes.c */
1565 EXPORT_SYMBOL_GPL(jprobe_return);