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