kprobes: Add mcount to the kprobes blacklist
[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 #include <linux/ftrace.h>
48
49 #include <asm-generic/sections.h>
50 #include <asm/cacheflush.h>
51 #include <asm/errno.h>
52 #include <asm/uaccess.h>
53
54 #define KPROBE_HASH_BITS 6
55 #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
56
57
58 /*
59  * Some oddball architectures like 64bit powerpc have function descriptors
60  * so this must be overridable.
61  */
62 #ifndef kprobe_lookup_name
63 #define kprobe_lookup_name(name, addr) \
64         addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name)))
65 #endif
66
67 static int kprobes_initialized;
68 static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
69 static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
70
71 /* NOTE: change this value only with kprobe_mutex held */
72 static bool kprobes_all_disarmed;
73
74 static DEFINE_MUTEX(kprobe_mutex);      /* Protects kprobe_table */
75 static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
76 static struct {
77         spinlock_t lock ____cacheline_aligned_in_smp;
78 } kretprobe_table_locks[KPROBE_TABLE_SIZE];
79
80 static spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
81 {
82         return &(kretprobe_table_locks[hash].lock);
83 }
84
85 /*
86  * Normally, functions that we'd want to prohibit kprobes in, are marked
87  * __kprobes. But, there are cases where such functions already belong to
88  * a different section (__sched for preempt_schedule)
89  *
90  * For such cases, we now have a blacklist
91  */
92 static struct kprobe_blackpoint kprobe_blacklist[] = {
93         {"preempt_schedule",},
94         {"native_get_debugreg",},
95         {"irq_entries_start",},
96         {"common_interrupt",},
97         {"mcount",},    /* mcount can be called from everywhere */
98         {NULL}    /* Terminator */
99 };
100
101 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
102 /*
103  * kprobe->ainsn.insn points to the copy of the instruction to be
104  * single-stepped. x86_64, POWER4 and above have no-exec support and
105  * stepping on the instruction on a vmalloced/kmalloced/data page
106  * is a recipe for disaster
107  */
108 #define INSNS_PER_PAGE  (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
109
110 struct kprobe_insn_page {
111         struct list_head list;
112         kprobe_opcode_t *insns;         /* Page of instruction slots */
113         char slot_used[INSNS_PER_PAGE];
114         int nused;
115         int ngarbage;
116 };
117
118 enum kprobe_slot_state {
119         SLOT_CLEAN = 0,
120         SLOT_DIRTY = 1,
121         SLOT_USED = 2,
122 };
123
124 static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_pages */
125 static LIST_HEAD(kprobe_insn_pages);
126 static int kprobe_garbage_slots;
127 static int collect_garbage_slots(void);
128
129 /**
130  * __get_insn_slot() - Find a slot on an executable page for an instruction.
131  * We allocate an executable page if there's no room on existing ones.
132  */
133 static kprobe_opcode_t __kprobes *__get_insn_slot(void)
134 {
135         struct kprobe_insn_page *kip;
136
137  retry:
138         list_for_each_entry(kip, &kprobe_insn_pages, list) {
139                 if (kip->nused < INSNS_PER_PAGE) {
140                         int i;
141                         for (i = 0; i < INSNS_PER_PAGE; i++) {
142                                 if (kip->slot_used[i] == SLOT_CLEAN) {
143                                         kip->slot_used[i] = SLOT_USED;
144                                         kip->nused++;
145                                         return kip->insns + (i * MAX_INSN_SIZE);
146                                 }
147                         }
148                         /* Surprise!  No unused slots.  Fix kip->nused. */
149                         kip->nused = INSNS_PER_PAGE;
150                 }
151         }
152
153         /* If there are any garbage slots, collect it and try again. */
154         if (kprobe_garbage_slots && collect_garbage_slots() == 0) {
155                 goto retry;
156         }
157         /* All out of space.  Need to allocate a new page. Use slot 0. */
158         kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL);
159         if (!kip)
160                 return NULL;
161
162         /*
163          * Use module_alloc so this page is within +/- 2GB of where the
164          * kernel image and loaded module images reside. This is required
165          * so x86_64 can correctly handle the %rip-relative fixups.
166          */
167         kip->insns = module_alloc(PAGE_SIZE);
168         if (!kip->insns) {
169                 kfree(kip);
170                 return NULL;
171         }
172         INIT_LIST_HEAD(&kip->list);
173         list_add(&kip->list, &kprobe_insn_pages);
174         memset(kip->slot_used, SLOT_CLEAN, INSNS_PER_PAGE);
175         kip->slot_used[0] = SLOT_USED;
176         kip->nused = 1;
177         kip->ngarbage = 0;
178         return kip->insns;
179 }
180
181 kprobe_opcode_t __kprobes *get_insn_slot(void)
182 {
183         kprobe_opcode_t *ret;
184         mutex_lock(&kprobe_insn_mutex);
185         ret = __get_insn_slot();
186         mutex_unlock(&kprobe_insn_mutex);
187         return ret;
188 }
189
190 /* Return 1 if all garbages are collected, otherwise 0. */
191 static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
192 {
193         kip->slot_used[idx] = SLOT_CLEAN;
194         kip->nused--;
195         if (kip->nused == 0) {
196                 /*
197                  * Page is no longer in use.  Free it unless
198                  * it's the last one.  We keep the last one
199                  * so as not to have to set it up again the
200                  * next time somebody inserts a probe.
201                  */
202                 if (!list_is_singular(&kprobe_insn_pages)) {
203                         list_del(&kip->list);
204                         module_free(NULL, kip->insns);
205                         kfree(kip);
206                 }
207                 return 1;
208         }
209         return 0;
210 }
211
212 static int __kprobes collect_garbage_slots(void)
213 {
214         struct kprobe_insn_page *kip, *next;
215
216         /* Ensure no-one is interrupted on the garbages */
217         synchronize_sched();
218
219         list_for_each_entry_safe(kip, next, &kprobe_insn_pages, list) {
220                 int i;
221                 if (kip->ngarbage == 0)
222                         continue;
223                 kip->ngarbage = 0;      /* we will collect all garbages */
224                 for (i = 0; i < INSNS_PER_PAGE; i++) {
225                         if (kip->slot_used[i] == SLOT_DIRTY &&
226                             collect_one_slot(kip, i))
227                                 break;
228                 }
229         }
230         kprobe_garbage_slots = 0;
231         return 0;
232 }
233
234 void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
235 {
236         struct kprobe_insn_page *kip;
237
238         mutex_lock(&kprobe_insn_mutex);
239         list_for_each_entry(kip, &kprobe_insn_pages, list) {
240                 if (kip->insns <= slot &&
241                     slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) {
242                         int i = (slot - kip->insns) / MAX_INSN_SIZE;
243                         if (dirty) {
244                                 kip->slot_used[i] = SLOT_DIRTY;
245                                 kip->ngarbage++;
246                         } else
247                                 collect_one_slot(kip, i);
248                         break;
249                 }
250         }
251
252         if (dirty && ++kprobe_garbage_slots > INSNS_PER_PAGE)
253                 collect_garbage_slots();
254
255         mutex_unlock(&kprobe_insn_mutex);
256 }
257 #endif
258
259 /* We have preemption disabled.. so it is safe to use __ versions */
260 static inline void set_kprobe_instance(struct kprobe *kp)
261 {
262         __get_cpu_var(kprobe_instance) = kp;
263 }
264
265 static inline void reset_kprobe_instance(void)
266 {
267         __get_cpu_var(kprobe_instance) = NULL;
268 }
269
270 /*
271  * This routine is called either:
272  *      - under the kprobe_mutex - during kprobe_[un]register()
273  *                              OR
274  *      - with preemption disabled - from arch/xxx/kernel/kprobes.c
275  */
276 struct kprobe __kprobes *get_kprobe(void *addr)
277 {
278         struct hlist_head *head;
279         struct hlist_node *node;
280         struct kprobe *p;
281
282         head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
283         hlist_for_each_entry_rcu(p, node, head, hlist) {
284                 if (p->addr == addr)
285                         return p;
286         }
287         return NULL;
288 }
289
290 /* Arm a kprobe with text_mutex */
291 static void __kprobes arm_kprobe(struct kprobe *kp)
292 {
293         mutex_lock(&text_mutex);
294         arch_arm_kprobe(kp);
295         mutex_unlock(&text_mutex);
296 }
297
298 /* Disarm a kprobe with text_mutex */
299 static void __kprobes disarm_kprobe(struct kprobe *kp)
300 {
301         mutex_lock(&text_mutex);
302         arch_disarm_kprobe(kp);
303         mutex_unlock(&text_mutex);
304 }
305
306 /*
307  * Aggregate handlers for multiple kprobes support - these handlers
308  * take care of invoking the individual kprobe handlers on p->list
309  */
310 static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
311 {
312         struct kprobe *kp;
313
314         list_for_each_entry_rcu(kp, &p->list, list) {
315                 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
316                         set_kprobe_instance(kp);
317                         if (kp->pre_handler(kp, regs))
318                                 return 1;
319                 }
320                 reset_kprobe_instance();
321         }
322         return 0;
323 }
324
325 static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
326                                         unsigned long flags)
327 {
328         struct kprobe *kp;
329
330         list_for_each_entry_rcu(kp, &p->list, list) {
331                 if (kp->post_handler && likely(!kprobe_disabled(kp))) {
332                         set_kprobe_instance(kp);
333                         kp->post_handler(kp, regs, flags);
334                         reset_kprobe_instance();
335                 }
336         }
337 }
338
339 static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
340                                         int trapnr)
341 {
342         struct kprobe *cur = __get_cpu_var(kprobe_instance);
343
344         /*
345          * if we faulted "during" the execution of a user specified
346          * probe handler, invoke just that probe's fault handler
347          */
348         if (cur && cur->fault_handler) {
349                 if (cur->fault_handler(cur, regs, trapnr))
350                         return 1;
351         }
352         return 0;
353 }
354
355 static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
356 {
357         struct kprobe *cur = __get_cpu_var(kprobe_instance);
358         int ret = 0;
359
360         if (cur && cur->break_handler) {
361                 if (cur->break_handler(cur, regs))
362                         ret = 1;
363         }
364         reset_kprobe_instance();
365         return ret;
366 }
367
368 /* Walks the list and increments nmissed count for multiprobe case */
369 void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
370 {
371         struct kprobe *kp;
372         if (p->pre_handler != aggr_pre_handler) {
373                 p->nmissed++;
374         } else {
375                 list_for_each_entry_rcu(kp, &p->list, list)
376                         kp->nmissed++;
377         }
378         return;
379 }
380
381 void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
382                                 struct hlist_head *head)
383 {
384         struct kretprobe *rp = ri->rp;
385
386         /* remove rp inst off the rprobe_inst_table */
387         hlist_del(&ri->hlist);
388         INIT_HLIST_NODE(&ri->hlist);
389         if (likely(rp)) {
390                 spin_lock(&rp->lock);
391                 hlist_add_head(&ri->hlist, &rp->free_instances);
392                 spin_unlock(&rp->lock);
393         } else
394                 /* Unregistering */
395                 hlist_add_head(&ri->hlist, head);
396 }
397
398 void __kprobes kretprobe_hash_lock(struct task_struct *tsk,
399                          struct hlist_head **head, unsigned long *flags)
400 {
401         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
402         spinlock_t *hlist_lock;
403
404         *head = &kretprobe_inst_table[hash];
405         hlist_lock = kretprobe_table_lock_ptr(hash);
406         spin_lock_irqsave(hlist_lock, *flags);
407 }
408
409 static void __kprobes kretprobe_table_lock(unsigned long hash,
410         unsigned long *flags)
411 {
412         spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
413         spin_lock_irqsave(hlist_lock, *flags);
414 }
415
416 void __kprobes kretprobe_hash_unlock(struct task_struct *tsk,
417         unsigned long *flags)
418 {
419         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
420         spinlock_t *hlist_lock;
421
422         hlist_lock = kretprobe_table_lock_ptr(hash);
423         spin_unlock_irqrestore(hlist_lock, *flags);
424 }
425
426 void __kprobes kretprobe_table_unlock(unsigned long hash, unsigned long *flags)
427 {
428         spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
429         spin_unlock_irqrestore(hlist_lock, *flags);
430 }
431
432 /*
433  * This function is called from finish_task_switch when task tk becomes dead,
434  * so that we can recycle any function-return probe instances associated
435  * with this task. These left over instances represent probed functions
436  * that have been called but will never return.
437  */
438 void __kprobes kprobe_flush_task(struct task_struct *tk)
439 {
440         struct kretprobe_instance *ri;
441         struct hlist_head *head, empty_rp;
442         struct hlist_node *node, *tmp;
443         unsigned long hash, flags = 0;
444
445         if (unlikely(!kprobes_initialized))
446                 /* Early boot.  kretprobe_table_locks not yet initialized. */
447                 return;
448
449         hash = hash_ptr(tk, KPROBE_HASH_BITS);
450         head = &kretprobe_inst_table[hash];
451         kretprobe_table_lock(hash, &flags);
452         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
453                 if (ri->task == tk)
454                         recycle_rp_inst(ri, &empty_rp);
455         }
456         kretprobe_table_unlock(hash, &flags);
457         INIT_HLIST_HEAD(&empty_rp);
458         hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
459                 hlist_del(&ri->hlist);
460                 kfree(ri);
461         }
462 }
463
464 static inline void free_rp_inst(struct kretprobe *rp)
465 {
466         struct kretprobe_instance *ri;
467         struct hlist_node *pos, *next;
468
469         hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, hlist) {
470                 hlist_del(&ri->hlist);
471                 kfree(ri);
472         }
473 }
474
475 static void __kprobes cleanup_rp_inst(struct kretprobe *rp)
476 {
477         unsigned long flags, hash;
478         struct kretprobe_instance *ri;
479         struct hlist_node *pos, *next;
480         struct hlist_head *head;
481
482         /* No race here */
483         for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
484                 kretprobe_table_lock(hash, &flags);
485                 head = &kretprobe_inst_table[hash];
486                 hlist_for_each_entry_safe(ri, pos, next, head, hlist) {
487                         if (ri->rp == rp)
488                                 ri->rp = NULL;
489                 }
490                 kretprobe_table_unlock(hash, &flags);
491         }
492         free_rp_inst(rp);
493 }
494
495 /*
496  * Keep all fields in the kprobe consistent
497  */
498 static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p)
499 {
500         memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t));
501         memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn));
502 }
503
504 /*
505 * Add the new probe to ap->list. Fail if this is the
506 * second jprobe at the address - two jprobes can't coexist
507 */
508 static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p)
509 {
510         BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
511         if (p->break_handler) {
512                 if (ap->break_handler)
513                         return -EEXIST;
514                 list_add_tail_rcu(&p->list, &ap->list);
515                 ap->break_handler = aggr_break_handler;
516         } else
517                 list_add_rcu(&p->list, &ap->list);
518         if (p->post_handler && !ap->post_handler)
519                 ap->post_handler = aggr_post_handler;
520
521         if (kprobe_disabled(ap) && !kprobe_disabled(p)) {
522                 ap->flags &= ~KPROBE_FLAG_DISABLED;
523                 if (!kprobes_all_disarmed)
524                         /* Arm the breakpoint again. */
525                         arm_kprobe(ap);
526         }
527         return 0;
528 }
529
530 /*
531  * Fill in the required fields of the "manager kprobe". Replace the
532  * earlier kprobe in the hlist with the manager kprobe
533  */
534 static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
535 {
536         copy_kprobe(p, ap);
537         flush_insn_slot(ap);
538         ap->addr = p->addr;
539         ap->flags = p->flags;
540         ap->pre_handler = aggr_pre_handler;
541         ap->fault_handler = aggr_fault_handler;
542         /* We don't care the kprobe which has gone. */
543         if (p->post_handler && !kprobe_gone(p))
544                 ap->post_handler = aggr_post_handler;
545         if (p->break_handler && !kprobe_gone(p))
546                 ap->break_handler = aggr_break_handler;
547
548         INIT_LIST_HEAD(&ap->list);
549         list_add_rcu(&p->list, &ap->list);
550
551         hlist_replace_rcu(&p->hlist, &ap->hlist);
552 }
553
554 /*
555  * This is the second or subsequent kprobe at the address - handle
556  * the intricacies
557  */
558 static int __kprobes register_aggr_kprobe(struct kprobe *old_p,
559                                           struct kprobe *p)
560 {
561         int ret = 0;
562         struct kprobe *ap = old_p;
563
564         if (old_p->pre_handler != aggr_pre_handler) {
565                 /* If old_p is not an aggr_probe, create new aggr_kprobe. */
566                 ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL);
567                 if (!ap)
568                         return -ENOMEM;
569                 add_aggr_kprobe(ap, old_p);
570         }
571
572         if (kprobe_gone(ap)) {
573                 /*
574                  * Attempting to insert new probe at the same location that
575                  * had a probe in the module vaddr area which already
576                  * freed. So, the instruction slot has already been
577                  * released. We need a new slot for the new probe.
578                  */
579                 ret = arch_prepare_kprobe(ap);
580                 if (ret)
581                         /*
582                          * Even if fail to allocate new slot, don't need to
583                          * free aggr_probe. It will be used next time, or
584                          * freed by unregister_kprobe.
585                          */
586                         return ret;
587
588                 /*
589                  * Clear gone flag to prevent allocating new slot again, and
590                  * set disabled flag because it is not armed yet.
591                  */
592                 ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
593                             | KPROBE_FLAG_DISABLED;
594         }
595
596         copy_kprobe(ap, p);
597         return add_new_kprobe(ap, p);
598 }
599
600 /* Try to disable aggr_kprobe, and return 1 if succeeded.*/
601 static int __kprobes try_to_disable_aggr_kprobe(struct kprobe *p)
602 {
603         struct kprobe *kp;
604
605         list_for_each_entry_rcu(kp, &p->list, list) {
606                 if (!kprobe_disabled(kp))
607                         /*
608                          * There is an active probe on the list.
609                          * We can't disable aggr_kprobe.
610                          */
611                         return 0;
612         }
613         p->flags |= KPROBE_FLAG_DISABLED;
614         return 1;
615 }
616
617 static int __kprobes in_kprobes_functions(unsigned long addr)
618 {
619         struct kprobe_blackpoint *kb;
620
621         if (addr >= (unsigned long)__kprobes_text_start &&
622             addr < (unsigned long)__kprobes_text_end)
623                 return -EINVAL;
624         /*
625          * If there exists a kprobe_blacklist, verify and
626          * fail any probe registration in the prohibited area
627          */
628         for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
629                 if (kb->start_addr) {
630                         if (addr >= kb->start_addr &&
631                             addr < (kb->start_addr + kb->range))
632                                 return -EINVAL;
633                 }
634         }
635         return 0;
636 }
637
638 /*
639  * If we have a symbol_name argument, look it up and add the offset field
640  * to it. This way, we can specify a relative address to a symbol.
641  */
642 static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p)
643 {
644         kprobe_opcode_t *addr = p->addr;
645         if (p->symbol_name) {
646                 if (addr)
647                         return NULL;
648                 kprobe_lookup_name(p->symbol_name, addr);
649         }
650
651         if (!addr)
652                 return NULL;
653         return (kprobe_opcode_t *)(((char *)addr) + p->offset);
654 }
655
656 /* Check passed kprobe is valid and return kprobe in kprobe_table. */
657 static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p)
658 {
659         struct kprobe *old_p, *list_p;
660
661         old_p = get_kprobe(p->addr);
662         if (unlikely(!old_p))
663                 return NULL;
664
665         if (p != old_p) {
666                 list_for_each_entry_rcu(list_p, &old_p->list, list)
667                         if (list_p == p)
668                         /* kprobe p is a valid probe */
669                                 goto valid;
670                 return NULL;
671         }
672 valid:
673         return old_p;
674 }
675
676 /* Return error if the kprobe is being re-registered */
677 static inline int check_kprobe_rereg(struct kprobe *p)
678 {
679         int ret = 0;
680         struct kprobe *old_p;
681
682         mutex_lock(&kprobe_mutex);
683         old_p = __get_valid_kprobe(p);
684         if (old_p)
685                 ret = -EINVAL;
686         mutex_unlock(&kprobe_mutex);
687         return ret;
688 }
689
690 int __kprobes register_kprobe(struct kprobe *p)
691 {
692         int ret = 0;
693         struct kprobe *old_p;
694         struct module *probed_mod;
695         kprobe_opcode_t *addr;
696
697         addr = kprobe_addr(p);
698         if (!addr)
699                 return -EINVAL;
700         p->addr = addr;
701
702         ret = check_kprobe_rereg(p);
703         if (ret)
704                 return ret;
705
706         preempt_disable();
707         if (!kernel_text_address((unsigned long) p->addr) ||
708             in_kprobes_functions((unsigned long) p->addr) ||
709             ftrace_text_reserved(p->addr, p->addr)) {
710                 preempt_enable();
711                 return -EINVAL;
712         }
713
714         /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
715         p->flags &= KPROBE_FLAG_DISABLED;
716
717         /*
718          * Check if are we probing a module.
719          */
720         probed_mod = __module_text_address((unsigned long) p->addr);
721         if (probed_mod) {
722                 /*
723                  * We must hold a refcount of the probed module while updating
724                  * its code to prohibit unexpected unloading.
725                  */
726                 if (unlikely(!try_module_get(probed_mod))) {
727                         preempt_enable();
728                         return -EINVAL;
729                 }
730                 /*
731                  * If the module freed .init.text, we couldn't insert
732                  * kprobes in there.
733                  */
734                 if (within_module_init((unsigned long)p->addr, probed_mod) &&
735                     probed_mod->state != MODULE_STATE_COMING) {
736                         module_put(probed_mod);
737                         preempt_enable();
738                         return -EINVAL;
739                 }
740         }
741         preempt_enable();
742
743         p->nmissed = 0;
744         INIT_LIST_HEAD(&p->list);
745         mutex_lock(&kprobe_mutex);
746         old_p = get_kprobe(p->addr);
747         if (old_p) {
748                 ret = register_aggr_kprobe(old_p, p);
749                 goto out;
750         }
751
752         mutex_lock(&text_mutex);
753         ret = arch_prepare_kprobe(p);
754         if (ret)
755                 goto out_unlock_text;
756
757         INIT_HLIST_NODE(&p->hlist);
758         hlist_add_head_rcu(&p->hlist,
759                        &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
760
761         if (!kprobes_all_disarmed && !kprobe_disabled(p))
762                 arch_arm_kprobe(p);
763
764 out_unlock_text:
765         mutex_unlock(&text_mutex);
766 out:
767         mutex_unlock(&kprobe_mutex);
768
769         if (probed_mod)
770                 module_put(probed_mod);
771
772         return ret;
773 }
774 EXPORT_SYMBOL_GPL(register_kprobe);
775
776 /*
777  * Unregister a kprobe without a scheduler synchronization.
778  */
779 static int __kprobes __unregister_kprobe_top(struct kprobe *p)
780 {
781         struct kprobe *old_p, *list_p;
782
783         old_p = __get_valid_kprobe(p);
784         if (old_p == NULL)
785                 return -EINVAL;
786
787         if (old_p == p ||
788             (old_p->pre_handler == aggr_pre_handler &&
789              list_is_singular(&old_p->list))) {
790                 /*
791                  * Only probe on the hash list. Disarm only if kprobes are
792                  * enabled and not gone - otherwise, the breakpoint would
793                  * already have been removed. We save on flushing icache.
794                  */
795                 if (!kprobes_all_disarmed && !kprobe_disabled(old_p))
796                         disarm_kprobe(p);
797                 hlist_del_rcu(&old_p->hlist);
798         } else {
799                 if (p->break_handler && !kprobe_gone(p))
800                         old_p->break_handler = NULL;
801                 if (p->post_handler && !kprobe_gone(p)) {
802                         list_for_each_entry_rcu(list_p, &old_p->list, list) {
803                                 if ((list_p != p) && (list_p->post_handler))
804                                         goto noclean;
805                         }
806                         old_p->post_handler = NULL;
807                 }
808 noclean:
809                 list_del_rcu(&p->list);
810                 if (!kprobe_disabled(old_p)) {
811                         try_to_disable_aggr_kprobe(old_p);
812                         if (!kprobes_all_disarmed && kprobe_disabled(old_p))
813                                 disarm_kprobe(old_p);
814                 }
815         }
816         return 0;
817 }
818
819 static void __kprobes __unregister_kprobe_bottom(struct kprobe *p)
820 {
821         struct kprobe *old_p;
822
823         if (list_empty(&p->list))
824                 arch_remove_kprobe(p);
825         else if (list_is_singular(&p->list)) {
826                 /* "p" is the last child of an aggr_kprobe */
827                 old_p = list_entry(p->list.next, struct kprobe, list);
828                 list_del(&p->list);
829                 arch_remove_kprobe(old_p);
830                 kfree(old_p);
831         }
832 }
833
834 int __kprobes register_kprobes(struct kprobe **kps, int num)
835 {
836         int i, ret = 0;
837
838         if (num <= 0)
839                 return -EINVAL;
840         for (i = 0; i < num; i++) {
841                 ret = register_kprobe(kps[i]);
842                 if (ret < 0) {
843                         if (i > 0)
844                                 unregister_kprobes(kps, i);
845                         break;
846                 }
847         }
848         return ret;
849 }
850 EXPORT_SYMBOL_GPL(register_kprobes);
851
852 void __kprobes unregister_kprobe(struct kprobe *p)
853 {
854         unregister_kprobes(&p, 1);
855 }
856 EXPORT_SYMBOL_GPL(unregister_kprobe);
857
858 void __kprobes unregister_kprobes(struct kprobe **kps, int num)
859 {
860         int i;
861
862         if (num <= 0)
863                 return;
864         mutex_lock(&kprobe_mutex);
865         for (i = 0; i < num; i++)
866                 if (__unregister_kprobe_top(kps[i]) < 0)
867                         kps[i]->addr = NULL;
868         mutex_unlock(&kprobe_mutex);
869
870         synchronize_sched();
871         for (i = 0; i < num; i++)
872                 if (kps[i]->addr)
873                         __unregister_kprobe_bottom(kps[i]);
874 }
875 EXPORT_SYMBOL_GPL(unregister_kprobes);
876
877 static struct notifier_block kprobe_exceptions_nb = {
878         .notifier_call = kprobe_exceptions_notify,
879         .priority = 0x7fffffff /* we need to be notified first */
880 };
881
882 unsigned long __weak arch_deref_entry_point(void *entry)
883 {
884         return (unsigned long)entry;
885 }
886
887 int __kprobes register_jprobes(struct jprobe **jps, int num)
888 {
889         struct jprobe *jp;
890         int ret = 0, i;
891
892         if (num <= 0)
893                 return -EINVAL;
894         for (i = 0; i < num; i++) {
895                 unsigned long addr;
896                 jp = jps[i];
897                 addr = arch_deref_entry_point(jp->entry);
898
899                 if (!kernel_text_address(addr))
900                         ret = -EINVAL;
901                 else {
902                         /* Todo: Verify probepoint is a function entry point */
903                         jp->kp.pre_handler = setjmp_pre_handler;
904                         jp->kp.break_handler = longjmp_break_handler;
905                         ret = register_kprobe(&jp->kp);
906                 }
907                 if (ret < 0) {
908                         if (i > 0)
909                                 unregister_jprobes(jps, i);
910                         break;
911                 }
912         }
913         return ret;
914 }
915 EXPORT_SYMBOL_GPL(register_jprobes);
916
917 int __kprobes register_jprobe(struct jprobe *jp)
918 {
919         return register_jprobes(&jp, 1);
920 }
921 EXPORT_SYMBOL_GPL(register_jprobe);
922
923 void __kprobes unregister_jprobe(struct jprobe *jp)
924 {
925         unregister_jprobes(&jp, 1);
926 }
927 EXPORT_SYMBOL_GPL(unregister_jprobe);
928
929 void __kprobes unregister_jprobes(struct jprobe **jps, int num)
930 {
931         int i;
932
933         if (num <= 0)
934                 return;
935         mutex_lock(&kprobe_mutex);
936         for (i = 0; i < num; i++)
937                 if (__unregister_kprobe_top(&jps[i]->kp) < 0)
938                         jps[i]->kp.addr = NULL;
939         mutex_unlock(&kprobe_mutex);
940
941         synchronize_sched();
942         for (i = 0; i < num; i++) {
943                 if (jps[i]->kp.addr)
944                         __unregister_kprobe_bottom(&jps[i]->kp);
945         }
946 }
947 EXPORT_SYMBOL_GPL(unregister_jprobes);
948
949 #ifdef CONFIG_KRETPROBES
950 /*
951  * This kprobe pre_handler is registered with every kretprobe. When probe
952  * hits it will set up the return probe.
953  */
954 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
955                                            struct pt_regs *regs)
956 {
957         struct kretprobe *rp = container_of(p, struct kretprobe, kp);
958         unsigned long hash, flags = 0;
959         struct kretprobe_instance *ri;
960
961         /*TODO: consider to only swap the RA after the last pre_handler fired */
962         hash = hash_ptr(current, KPROBE_HASH_BITS);
963         spin_lock_irqsave(&rp->lock, flags);
964         if (!hlist_empty(&rp->free_instances)) {
965                 ri = hlist_entry(rp->free_instances.first,
966                                 struct kretprobe_instance, hlist);
967                 hlist_del(&ri->hlist);
968                 spin_unlock_irqrestore(&rp->lock, flags);
969
970                 ri->rp = rp;
971                 ri->task = current;
972
973                 if (rp->entry_handler && rp->entry_handler(ri, regs))
974                         return 0;
975
976                 arch_prepare_kretprobe(ri, regs);
977
978                 /* XXX(hch): why is there no hlist_move_head? */
979                 INIT_HLIST_NODE(&ri->hlist);
980                 kretprobe_table_lock(hash, &flags);
981                 hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
982                 kretprobe_table_unlock(hash, &flags);
983         } else {
984                 rp->nmissed++;
985                 spin_unlock_irqrestore(&rp->lock, flags);
986         }
987         return 0;
988 }
989
990 int __kprobes register_kretprobe(struct kretprobe *rp)
991 {
992         int ret = 0;
993         struct kretprobe_instance *inst;
994         int i;
995         void *addr;
996
997         if (kretprobe_blacklist_size) {
998                 addr = kprobe_addr(&rp->kp);
999                 if (!addr)
1000                         return -EINVAL;
1001
1002                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1003                         if (kretprobe_blacklist[i].addr == addr)
1004                                 return -EINVAL;
1005                 }
1006         }
1007
1008         rp->kp.pre_handler = pre_handler_kretprobe;
1009         rp->kp.post_handler = NULL;
1010         rp->kp.fault_handler = NULL;
1011         rp->kp.break_handler = NULL;
1012
1013         /* Pre-allocate memory for max kretprobe instances */
1014         if (rp->maxactive <= 0) {
1015 #ifdef CONFIG_PREEMPT
1016                 rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
1017 #else
1018                 rp->maxactive = num_possible_cpus();
1019 #endif
1020         }
1021         spin_lock_init(&rp->lock);
1022         INIT_HLIST_HEAD(&rp->free_instances);
1023         for (i = 0; i < rp->maxactive; i++) {
1024                 inst = kmalloc(sizeof(struct kretprobe_instance) +
1025                                rp->data_size, GFP_KERNEL);
1026                 if (inst == NULL) {
1027                         free_rp_inst(rp);
1028                         return -ENOMEM;
1029                 }
1030                 INIT_HLIST_NODE(&inst->hlist);
1031                 hlist_add_head(&inst->hlist, &rp->free_instances);
1032         }
1033
1034         rp->nmissed = 0;
1035         /* Establish function entry probe point */
1036         ret = register_kprobe(&rp->kp);
1037         if (ret != 0)
1038                 free_rp_inst(rp);
1039         return ret;
1040 }
1041 EXPORT_SYMBOL_GPL(register_kretprobe);
1042
1043 int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1044 {
1045         int ret = 0, i;
1046
1047         if (num <= 0)
1048                 return -EINVAL;
1049         for (i = 0; i < num; i++) {
1050                 ret = register_kretprobe(rps[i]);
1051                 if (ret < 0) {
1052                         if (i > 0)
1053                                 unregister_kretprobes(rps, i);
1054                         break;
1055                 }
1056         }
1057         return ret;
1058 }
1059 EXPORT_SYMBOL_GPL(register_kretprobes);
1060
1061 void __kprobes unregister_kretprobe(struct kretprobe *rp)
1062 {
1063         unregister_kretprobes(&rp, 1);
1064 }
1065 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1066
1067 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1068 {
1069         int i;
1070
1071         if (num <= 0)
1072                 return;
1073         mutex_lock(&kprobe_mutex);
1074         for (i = 0; i < num; i++)
1075                 if (__unregister_kprobe_top(&rps[i]->kp) < 0)
1076                         rps[i]->kp.addr = NULL;
1077         mutex_unlock(&kprobe_mutex);
1078
1079         synchronize_sched();
1080         for (i = 0; i < num; i++) {
1081                 if (rps[i]->kp.addr) {
1082                         __unregister_kprobe_bottom(&rps[i]->kp);
1083                         cleanup_rp_inst(rps[i]);
1084                 }
1085         }
1086 }
1087 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1088
1089 #else /* CONFIG_KRETPROBES */
1090 int __kprobes register_kretprobe(struct kretprobe *rp)
1091 {
1092         return -ENOSYS;
1093 }
1094 EXPORT_SYMBOL_GPL(register_kretprobe);
1095
1096 int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1097 {
1098         return -ENOSYS;
1099 }
1100 EXPORT_SYMBOL_GPL(register_kretprobes);
1101
1102 void __kprobes unregister_kretprobe(struct kretprobe *rp)
1103 {
1104 }
1105 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1106
1107 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1108 {
1109 }
1110 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1111
1112 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
1113                                            struct pt_regs *regs)
1114 {
1115         return 0;
1116 }
1117
1118 #endif /* CONFIG_KRETPROBES */
1119
1120 /* Set the kprobe gone and remove its instruction buffer. */
1121 static void __kprobes kill_kprobe(struct kprobe *p)
1122 {
1123         struct kprobe *kp;
1124
1125         p->flags |= KPROBE_FLAG_GONE;
1126         if (p->pre_handler == aggr_pre_handler) {
1127                 /*
1128                  * If this is an aggr_kprobe, we have to list all the
1129                  * chained probes and mark them GONE.
1130                  */
1131                 list_for_each_entry_rcu(kp, &p->list, list)
1132                         kp->flags |= KPROBE_FLAG_GONE;
1133                 p->post_handler = NULL;
1134                 p->break_handler = NULL;
1135         }
1136         /*
1137          * Here, we can remove insn_slot safely, because no thread calls
1138          * the original probed function (which will be freed soon) any more.
1139          */
1140         arch_remove_kprobe(p);
1141 }
1142
1143 void __kprobes dump_kprobe(struct kprobe *kp)
1144 {
1145         printk(KERN_WARNING "Dumping kprobe:\n");
1146         printk(KERN_WARNING "Name: %s\nAddress: %p\nOffset: %x\n",
1147                kp->symbol_name, kp->addr, kp->offset);
1148 }
1149
1150 /* Module notifier call back, checking kprobes on the module */
1151 static int __kprobes kprobes_module_callback(struct notifier_block *nb,
1152                                              unsigned long val, void *data)
1153 {
1154         struct module *mod = data;
1155         struct hlist_head *head;
1156         struct hlist_node *node;
1157         struct kprobe *p;
1158         unsigned int i;
1159         int checkcore = (val == MODULE_STATE_GOING);
1160
1161         if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
1162                 return NOTIFY_DONE;
1163
1164         /*
1165          * When MODULE_STATE_GOING was notified, both of module .text and
1166          * .init.text sections would be freed. When MODULE_STATE_LIVE was
1167          * notified, only .init.text section would be freed. We need to
1168          * disable kprobes which have been inserted in the sections.
1169          */
1170         mutex_lock(&kprobe_mutex);
1171         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1172                 head = &kprobe_table[i];
1173                 hlist_for_each_entry_rcu(p, node, head, hlist)
1174                         if (within_module_init((unsigned long)p->addr, mod) ||
1175                             (checkcore &&
1176                              within_module_core((unsigned long)p->addr, mod))) {
1177                                 /*
1178                                  * The vaddr this probe is installed will soon
1179                                  * be vfreed buy not synced to disk. Hence,
1180                                  * disarming the breakpoint isn't needed.
1181                                  */
1182                                 kill_kprobe(p);
1183                         }
1184         }
1185         mutex_unlock(&kprobe_mutex);
1186         return NOTIFY_DONE;
1187 }
1188
1189 static struct notifier_block kprobe_module_nb = {
1190         .notifier_call = kprobes_module_callback,
1191         .priority = 0
1192 };
1193
1194 static int __init init_kprobes(void)
1195 {
1196         int i, err = 0;
1197         unsigned long offset = 0, size = 0;
1198         char *modname, namebuf[128];
1199         const char *symbol_name;
1200         void *addr;
1201         struct kprobe_blackpoint *kb;
1202
1203         /* FIXME allocate the probe table, currently defined statically */
1204         /* initialize all list heads */
1205         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1206                 INIT_HLIST_HEAD(&kprobe_table[i]);
1207                 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
1208                 spin_lock_init(&(kretprobe_table_locks[i].lock));
1209         }
1210
1211         /*
1212          * Lookup and populate the kprobe_blacklist.
1213          *
1214          * Unlike the kretprobe blacklist, we'll need to determine
1215          * the range of addresses that belong to the said functions,
1216          * since a kprobe need not necessarily be at the beginning
1217          * of a function.
1218          */
1219         for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
1220                 kprobe_lookup_name(kb->name, addr);
1221                 if (!addr)
1222                         continue;
1223
1224                 kb->start_addr = (unsigned long)addr;
1225                 symbol_name = kallsyms_lookup(kb->start_addr,
1226                                 &size, &offset, &modname, namebuf);
1227                 if (!symbol_name)
1228                         kb->range = 0;
1229                 else
1230                         kb->range = size;
1231         }
1232
1233         if (kretprobe_blacklist_size) {
1234                 /* lookup the function address from its name */
1235                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1236                         kprobe_lookup_name(kretprobe_blacklist[i].name,
1237                                            kretprobe_blacklist[i].addr);
1238                         if (!kretprobe_blacklist[i].addr)
1239                                 printk("kretprobe: lookup failed: %s\n",
1240                                        kretprobe_blacklist[i].name);
1241                 }
1242         }
1243
1244         /* By default, kprobes are armed */
1245         kprobes_all_disarmed = false;
1246
1247         err = arch_init_kprobes();
1248         if (!err)
1249                 err = register_die_notifier(&kprobe_exceptions_nb);
1250         if (!err)
1251                 err = register_module_notifier(&kprobe_module_nb);
1252
1253         kprobes_initialized = (err == 0);
1254
1255         if (!err)
1256                 init_test_probes();
1257         return err;
1258 }
1259
1260 #ifdef CONFIG_DEBUG_FS
1261 static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
1262                 const char *sym, int offset,char *modname)
1263 {
1264         char *kprobe_type;
1265
1266         if (p->pre_handler == pre_handler_kretprobe)
1267                 kprobe_type = "r";
1268         else if (p->pre_handler == setjmp_pre_handler)
1269                 kprobe_type = "j";
1270         else
1271                 kprobe_type = "k";
1272         if (sym)
1273                 seq_printf(pi, "%p  %s  %s+0x%x  %s %s%s\n",
1274                         p->addr, kprobe_type, sym, offset,
1275                         (modname ? modname : " "),
1276                         (kprobe_gone(p) ? "[GONE]" : ""),
1277                         ((kprobe_disabled(p) && !kprobe_gone(p)) ?
1278                          "[DISABLED]" : ""));
1279         else
1280                 seq_printf(pi, "%p  %s  %p %s%s\n",
1281                         p->addr, kprobe_type, p->addr,
1282                         (kprobe_gone(p) ? "[GONE]" : ""),
1283                         ((kprobe_disabled(p) && !kprobe_gone(p)) ?
1284                          "[DISABLED]" : ""));
1285 }
1286
1287 static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
1288 {
1289         return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
1290 }
1291
1292 static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
1293 {
1294         (*pos)++;
1295         if (*pos >= KPROBE_TABLE_SIZE)
1296                 return NULL;
1297         return pos;
1298 }
1299
1300 static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v)
1301 {
1302         /* Nothing to do */
1303 }
1304
1305 static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v)
1306 {
1307         struct hlist_head *head;
1308         struct hlist_node *node;
1309         struct kprobe *p, *kp;
1310         const char *sym = NULL;
1311         unsigned int i = *(loff_t *) v;
1312         unsigned long offset = 0;
1313         char *modname, namebuf[128];
1314
1315         head = &kprobe_table[i];
1316         preempt_disable();
1317         hlist_for_each_entry_rcu(p, node, head, hlist) {
1318                 sym = kallsyms_lookup((unsigned long)p->addr, NULL,
1319                                         &offset, &modname, namebuf);
1320                 if (p->pre_handler == aggr_pre_handler) {
1321                         list_for_each_entry_rcu(kp, &p->list, list)
1322                                 report_probe(pi, kp, sym, offset, modname);
1323                 } else
1324                         report_probe(pi, p, sym, offset, modname);
1325         }
1326         preempt_enable();
1327         return 0;
1328 }
1329
1330 static const struct seq_operations kprobes_seq_ops = {
1331         .start = kprobe_seq_start,
1332         .next  = kprobe_seq_next,
1333         .stop  = kprobe_seq_stop,
1334         .show  = show_kprobe_addr
1335 };
1336
1337 static int __kprobes kprobes_open(struct inode *inode, struct file *filp)
1338 {
1339         return seq_open(filp, &kprobes_seq_ops);
1340 }
1341
1342 static const struct file_operations debugfs_kprobes_operations = {
1343         .open           = kprobes_open,
1344         .read           = seq_read,
1345         .llseek         = seq_lseek,
1346         .release        = seq_release,
1347 };
1348
1349 /* Disable one kprobe */
1350 int __kprobes disable_kprobe(struct kprobe *kp)
1351 {
1352         int ret = 0;
1353         struct kprobe *p;
1354
1355         mutex_lock(&kprobe_mutex);
1356
1357         /* Check whether specified probe is valid. */
1358         p = __get_valid_kprobe(kp);
1359         if (unlikely(p == NULL)) {
1360                 ret = -EINVAL;
1361                 goto out;
1362         }
1363
1364         /* If the probe is already disabled (or gone), just return */
1365         if (kprobe_disabled(kp))
1366                 goto out;
1367
1368         kp->flags |= KPROBE_FLAG_DISABLED;
1369         if (p != kp)
1370                 /* When kp != p, p is always enabled. */
1371                 try_to_disable_aggr_kprobe(p);
1372
1373         if (!kprobes_all_disarmed && kprobe_disabled(p))
1374                 disarm_kprobe(p);
1375 out:
1376         mutex_unlock(&kprobe_mutex);
1377         return ret;
1378 }
1379 EXPORT_SYMBOL_GPL(disable_kprobe);
1380
1381 /* Enable one kprobe */
1382 int __kprobes enable_kprobe(struct kprobe *kp)
1383 {
1384         int ret = 0;
1385         struct kprobe *p;
1386
1387         mutex_lock(&kprobe_mutex);
1388
1389         /* Check whether specified probe is valid. */
1390         p = __get_valid_kprobe(kp);
1391         if (unlikely(p == NULL)) {
1392                 ret = -EINVAL;
1393                 goto out;
1394         }
1395
1396         if (kprobe_gone(kp)) {
1397                 /* This kprobe has gone, we couldn't enable it. */
1398                 ret = -EINVAL;
1399                 goto out;
1400         }
1401
1402         if (!kprobes_all_disarmed && kprobe_disabled(p))
1403                 arm_kprobe(p);
1404
1405         p->flags &= ~KPROBE_FLAG_DISABLED;
1406         if (p != kp)
1407                 kp->flags &= ~KPROBE_FLAG_DISABLED;
1408 out:
1409         mutex_unlock(&kprobe_mutex);
1410         return ret;
1411 }
1412 EXPORT_SYMBOL_GPL(enable_kprobe);
1413
1414 static void __kprobes arm_all_kprobes(void)
1415 {
1416         struct hlist_head *head;
1417         struct hlist_node *node;
1418         struct kprobe *p;
1419         unsigned int i;
1420
1421         mutex_lock(&kprobe_mutex);
1422
1423         /* If kprobes are armed, just return */
1424         if (!kprobes_all_disarmed)
1425                 goto already_enabled;
1426
1427         mutex_lock(&text_mutex);
1428         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1429                 head = &kprobe_table[i];
1430                 hlist_for_each_entry_rcu(p, node, head, hlist)
1431                         if (!kprobe_disabled(p))
1432                                 arch_arm_kprobe(p);
1433         }
1434         mutex_unlock(&text_mutex);
1435
1436         kprobes_all_disarmed = false;
1437         printk(KERN_INFO "Kprobes globally enabled\n");
1438
1439 already_enabled:
1440         mutex_unlock(&kprobe_mutex);
1441         return;
1442 }
1443
1444 static void __kprobes disarm_all_kprobes(void)
1445 {
1446         struct hlist_head *head;
1447         struct hlist_node *node;
1448         struct kprobe *p;
1449         unsigned int i;
1450
1451         mutex_lock(&kprobe_mutex);
1452
1453         /* If kprobes are already disarmed, just return */
1454         if (kprobes_all_disarmed)
1455                 goto already_disabled;
1456
1457         kprobes_all_disarmed = true;
1458         printk(KERN_INFO "Kprobes globally disabled\n");
1459         mutex_lock(&text_mutex);
1460         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1461                 head = &kprobe_table[i];
1462                 hlist_for_each_entry_rcu(p, node, head, hlist) {
1463                         if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
1464                                 arch_disarm_kprobe(p);
1465                 }
1466         }
1467
1468         mutex_unlock(&text_mutex);
1469         mutex_unlock(&kprobe_mutex);
1470         /* Allow all currently running kprobes to complete */
1471         synchronize_sched();
1472         return;
1473
1474 already_disabled:
1475         mutex_unlock(&kprobe_mutex);
1476         return;
1477 }
1478
1479 /*
1480  * XXX: The debugfs bool file interface doesn't allow for callbacks
1481  * when the bool state is switched. We can reuse that facility when
1482  * available
1483  */
1484 static ssize_t read_enabled_file_bool(struct file *file,
1485                char __user *user_buf, size_t count, loff_t *ppos)
1486 {
1487         char buf[3];
1488
1489         if (!kprobes_all_disarmed)
1490                 buf[0] = '1';
1491         else
1492                 buf[0] = '0';
1493         buf[1] = '\n';
1494         buf[2] = 0x00;
1495         return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
1496 }
1497
1498 static ssize_t write_enabled_file_bool(struct file *file,
1499                const char __user *user_buf, size_t count, loff_t *ppos)
1500 {
1501         char buf[32];
1502         int buf_size;
1503
1504         buf_size = min(count, (sizeof(buf)-1));
1505         if (copy_from_user(buf, user_buf, buf_size))
1506                 return -EFAULT;
1507
1508         switch (buf[0]) {
1509         case 'y':
1510         case 'Y':
1511         case '1':
1512                 arm_all_kprobes();
1513                 break;
1514         case 'n':
1515         case 'N':
1516         case '0':
1517                 disarm_all_kprobes();
1518                 break;
1519         }
1520
1521         return count;
1522 }
1523
1524 static const struct file_operations fops_kp = {
1525         .read =         read_enabled_file_bool,
1526         .write =        write_enabled_file_bool,
1527 };
1528
1529 static int __kprobes debugfs_kprobe_init(void)
1530 {
1531         struct dentry *dir, *file;
1532         unsigned int value = 1;
1533
1534         dir = debugfs_create_dir("kprobes", NULL);
1535         if (!dir)
1536                 return -ENOMEM;
1537
1538         file = debugfs_create_file("list", 0444, dir, NULL,
1539                                 &debugfs_kprobes_operations);
1540         if (!file) {
1541                 debugfs_remove(dir);
1542                 return -ENOMEM;
1543         }
1544
1545         file = debugfs_create_file("enabled", 0600, dir,
1546                                         &value, &fops_kp);
1547         if (!file) {
1548                 debugfs_remove(dir);
1549                 return -ENOMEM;
1550         }
1551
1552         return 0;
1553 }
1554
1555 late_initcall(debugfs_kprobe_init);
1556 #endif /* CONFIG_DEBUG_FS */
1557
1558 module_init(init_kprobes);
1559
1560 /* defined in arch/.../kernel/kprobes.c */
1561 EXPORT_SYMBOL_GPL(jprobe_return);