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TOMOYO Linux Cross Reference
Linux/kernel/kprobes.c

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  1 /*
  2  *  Kernel Probes (KProbes)
  3  *  kernel/kprobes.c
  4  *
  5  * This program is free software; you can redistribute it and/or modify
  6  * it under the terms of the GNU General Public License as published by
  7  * the Free Software Foundation; either version 2 of the License, or
  8  * (at your option) any later version.
  9  *
 10  * This program is distributed in the hope that it will be useful,
 11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 13  * GNU General Public License for more details.
 14  *
 15  * You should have received a copy of the GNU General Public License
 16  * along with this program; if not, write to the Free Software
 17  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 18  *
 19  * Copyright (C) IBM Corporation, 2002, 2004
 20  *
 21  * 2002-Oct     Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
 22  *              Probes initial implementation (includes suggestions from
 23  *              Rusty Russell).
 24  * 2004-Aug     Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with
 25  *              hlists and exceptions notifier as suggested by Andi Kleen.
 26  * 2004-July    Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
 27  *              interface to access function arguments.
 28  * 2004-Sep     Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
 29  *              exceptions notifier to be first on the priority list.
 30  * 2005-May     Hien Nguyen <hien@us.ibm.com>, Jim Keniston
 31  *              <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
 32  *              <prasanna@in.ibm.com> added function-return probes.
 33  */
 34 #include <linux/kprobes.h>
 35 #include <linux/hash.h>
 36 #include <linux/init.h>
 37 #include <linux/slab.h>
 38 #include <linux/stddef.h>
 39 #include <linux/module.h>
 40 #include <linux/moduleloader.h>
 41 #include <linux/kallsyms.h>
 42 #include <linux/freezer.h>
 43 #include <linux/seq_file.h>
 44 #include <linux/debugfs.h>
 45 #include <linux/sysctl.h>
 46 #include <linux/kdebug.h>
 47 #include <linux/memory.h>
 48 #include <linux/ftrace.h>
 49 #include <linux/cpu.h>
 50 #include <linux/jump_label.h>
 51 
 52 #include <asm-generic/sections.h>
 53 #include <asm/cacheflush.h>
 54 #include <asm/errno.h>
 55 #include <asm/uaccess.h>
 56 
 57 #define KPROBE_HASH_BITS 6
 58 #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
 59 
 60 
 61 /*
 62  * Some oddball architectures like 64bit powerpc have function descriptors
 63  * so this must be overridable.
 64  */
 65 #ifndef kprobe_lookup_name
 66 #define kprobe_lookup_name(name, addr) \
 67         addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name)))
 68 #endif
 69 
 70 static int kprobes_initialized;
 71 static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
 72 static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
 73 
 74 /* NOTE: change this value only with kprobe_mutex held */
 75 static bool kprobes_all_disarmed;
 76 
 77 /* This protects kprobe_table and optimizing_list */
 78 static DEFINE_MUTEX(kprobe_mutex);
 79 static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
 80 static struct {
 81         spinlock_t lock ____cacheline_aligned_in_smp;
 82 } kretprobe_table_locks[KPROBE_TABLE_SIZE];
 83 
 84 static spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
 85 {
 86         return &(kretprobe_table_locks[hash].lock);
 87 }
 88 
 89 /*
 90  * Normally, functions that we'd want to prohibit kprobes in, are marked
 91  * __kprobes. But, there are cases where such functions already belong to
 92  * a different section (__sched for preempt_schedule)
 93  *
 94  * For such cases, we now have a blacklist
 95  */
 96 static struct kprobe_blackpoint kprobe_blacklist[] = {
 97         {"preempt_schedule",},
 98         {"native_get_debugreg",},
 99         {"irq_entries_start",},
100         {"common_interrupt",},
101         {"mcount",},    /* mcount can be called from everywhere */
102         {NULL}    /* Terminator */
103 };
104 
105 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
106 /*
107  * kprobe->ainsn.insn points to the copy of the instruction to be
108  * single-stepped. x86_64, POWER4 and above have no-exec support and
109  * stepping on the instruction on a vmalloced/kmalloced/data page
110  * is a recipe for disaster
111  */
112 struct kprobe_insn_page {
113         struct list_head list;
114         kprobe_opcode_t *insns;         /* Page of instruction slots */
115         int nused;
116         int ngarbage;
117         char slot_used[];
118 };
119 
120 #define KPROBE_INSN_PAGE_SIZE(slots)                    \
121         (offsetof(struct kprobe_insn_page, slot_used) + \
122          (sizeof(char) * (slots)))
123 
124 struct kprobe_insn_cache {
125         struct list_head pages; /* list of kprobe_insn_page */
126         size_t insn_size;       /* size of instruction slot */
127         int nr_garbage;
128 };
129 
130 static int slots_per_page(struct kprobe_insn_cache *c)
131 {
132         return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));
133 }
134 
135 enum kprobe_slot_state {
136         SLOT_CLEAN = 0,
137         SLOT_DIRTY = 1,
138         SLOT_USED = 2,
139 };
140 
141 static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_slots */
142 static struct kprobe_insn_cache kprobe_insn_slots = {
143         .pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
144         .insn_size = MAX_INSN_SIZE,
145         .nr_garbage = 0,
146 };
147 static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c);
148 
149 /**
150  * __get_insn_slot() - Find a slot on an executable page for an instruction.
151  * We allocate an executable page if there's no room on existing ones.
152  */
153 static kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
154 {
155         struct kprobe_insn_page *kip;
156 
157  retry:
158         list_for_each_entry(kip, &c->pages, list) {
159                 if (kip->nused < slots_per_page(c)) {
160                         int i;
161                         for (i = 0; i < slots_per_page(c); i++) {
162                                 if (kip->slot_used[i] == SLOT_CLEAN) {
163                                         kip->slot_used[i] = SLOT_USED;
164                                         kip->nused++;
165                                         return kip->insns + (i * c->insn_size);
166                                 }
167                         }
168                         /* kip->nused is broken. Fix it. */
169                         kip->nused = slots_per_page(c);
170                         WARN_ON(1);
171                 }
172         }
173 
174         /* If there are any garbage slots, collect it and try again. */
175         if (c->nr_garbage && collect_garbage_slots(c) == 0)
176                 goto retry;
177 
178         /* All out of space.  Need to allocate a new page. */
179         kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
180         if (!kip)
181                 return NULL;
182 
183         /*
184          * Use module_alloc so this page is within +/- 2GB of where the
185          * kernel image and loaded module images reside. This is required
186          * so x86_64 can correctly handle the %rip-relative fixups.
187          */
188         kip->insns = module_alloc(PAGE_SIZE);
189         if (!kip->insns) {
190                 kfree(kip);
191                 return NULL;
192         }
193         INIT_LIST_HEAD(&kip->list);
194         memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c));
195         kip->slot_used[0] = SLOT_USED;
196         kip->nused = 1;
197         kip->ngarbage = 0;
198         list_add(&kip->list, &c->pages);
199         return kip->insns;
200 }
201 
202 
203 kprobe_opcode_t __kprobes *get_insn_slot(void)
204 {
205         kprobe_opcode_t *ret = NULL;
206 
207         mutex_lock(&kprobe_insn_mutex);
208         ret = __get_insn_slot(&kprobe_insn_slots);
209         mutex_unlock(&kprobe_insn_mutex);
210 
211         return ret;
212 }
213 
214 /* Return 1 if all garbages are collected, otherwise 0. */
215 static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
216 {
217         kip->slot_used[idx] = SLOT_CLEAN;
218         kip->nused--;
219         if (kip->nused == 0) {
220                 /*
221                  * Page is no longer in use.  Free it unless
222                  * it's the last one.  We keep the last one
223                  * so as not to have to set it up again the
224                  * next time somebody inserts a probe.
225                  */
226                 if (!list_is_singular(&kip->list)) {
227                         list_del(&kip->list);
228                         module_free(NULL, kip->insns);
229                         kfree(kip);
230                 }
231                 return 1;
232         }
233         return 0;
234 }
235 
236 static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c)
237 {
238         struct kprobe_insn_page *kip, *next;
239 
240         /* Ensure no-one is interrupted on the garbages */
241         synchronize_sched();
242 
243         list_for_each_entry_safe(kip, next, &c->pages, list) {
244                 int i;
245                 if (kip->ngarbage == 0)
246                         continue;
247                 kip->ngarbage = 0;      /* we will collect all garbages */
248                 for (i = 0; i < slots_per_page(c); i++) {
249                         if (kip->slot_used[i] == SLOT_DIRTY &&
250                             collect_one_slot(kip, i))
251                                 break;
252                 }
253         }
254         c->nr_garbage = 0;
255         return 0;
256 }
257 
258 static void __kprobes __free_insn_slot(struct kprobe_insn_cache *c,
259                                        kprobe_opcode_t *slot, int dirty)
260 {
261         struct kprobe_insn_page *kip;
262 
263         list_for_each_entry(kip, &c->pages, list) {
264                 long idx = ((long)slot - (long)kip->insns) /
265                                 (c->insn_size * sizeof(kprobe_opcode_t));
266                 if (idx >= 0 && idx < slots_per_page(c)) {
267                         WARN_ON(kip->slot_used[idx] != SLOT_USED);
268                         if (dirty) {
269                                 kip->slot_used[idx] = SLOT_DIRTY;
270                                 kip->ngarbage++;
271                                 if (++c->nr_garbage > slots_per_page(c))
272                                         collect_garbage_slots(c);
273                         } else
274                                 collect_one_slot(kip, idx);
275                         return;
276                 }
277         }
278         /* Could not free this slot. */
279         WARN_ON(1);
280 }
281 
282 void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
283 {
284         mutex_lock(&kprobe_insn_mutex);
285         __free_insn_slot(&kprobe_insn_slots, slot, dirty);
286         mutex_unlock(&kprobe_insn_mutex);
287 }
288 #ifdef CONFIG_OPTPROBES
289 /* For optimized_kprobe buffer */
290 static DEFINE_MUTEX(kprobe_optinsn_mutex); /* Protects kprobe_optinsn_slots */
291 static struct kprobe_insn_cache kprobe_optinsn_slots = {
292         .pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
293         /* .insn_size is initialized later */
294         .nr_garbage = 0,
295 };
296 /* Get a slot for optimized_kprobe buffer */
297 kprobe_opcode_t __kprobes *get_optinsn_slot(void)
298 {
299         kprobe_opcode_t *ret = NULL;
300 
301         mutex_lock(&kprobe_optinsn_mutex);
302         ret = __get_insn_slot(&kprobe_optinsn_slots);
303         mutex_unlock(&kprobe_optinsn_mutex);
304 
305         return ret;
306 }
307 
308 void __kprobes free_optinsn_slot(kprobe_opcode_t * slot, int dirty)
309 {
310         mutex_lock(&kprobe_optinsn_mutex);
311         __free_insn_slot(&kprobe_optinsn_slots, slot, dirty);
312         mutex_unlock(&kprobe_optinsn_mutex);
313 }
314 #endif
315 #endif
316 
317 /* We have preemption disabled.. so it is safe to use __ versions */
318 static inline void set_kprobe_instance(struct kprobe *kp)
319 {
320         __this_cpu_write(kprobe_instance, kp);
321 }
322 
323 static inline void reset_kprobe_instance(void)
324 {
325         __this_cpu_write(kprobe_instance, NULL);
326 }
327 
328 /*
329  * This routine is called either:
330  *      - under the kprobe_mutex - during kprobe_[un]register()
331  *                              OR
332  *      - with preemption disabled - from arch/xxx/kernel/kprobes.c
333  */
334 struct kprobe __kprobes *get_kprobe(void *addr)
335 {
336         struct hlist_head *head;
337         struct hlist_node *node;
338         struct kprobe *p;
339 
340         head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
341         hlist_for_each_entry_rcu(p, node, head, hlist) {
342                 if (p->addr == addr)
343                         return p;
344         }
345 
346         return NULL;
347 }
348 
349 static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs);
350 
351 /* Return true if the kprobe is an aggregator */
352 static inline int kprobe_aggrprobe(struct kprobe *p)
353 {
354         return p->pre_handler == aggr_pre_handler;
355 }
356 
357 /* Return true(!0) if the kprobe is unused */
358 static inline int kprobe_unused(struct kprobe *p)
359 {
360         return kprobe_aggrprobe(p) && kprobe_disabled(p) &&
361                list_empty(&p->list);
362 }
363 
364 /*
365  * Keep all fields in the kprobe consistent
366  */
367 static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p)
368 {
369         memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t));
370         memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn));
371 }
372 
373 #ifdef CONFIG_OPTPROBES
374 /* NOTE: change this value only with kprobe_mutex held */
375 static bool kprobes_allow_optimization;
376 
377 /*
378  * Call all pre_handler on the list, but ignores its return value.
379  * This must be called from arch-dep optimized caller.
380  */
381 void __kprobes opt_pre_handler(struct kprobe *p, struct pt_regs *regs)
382 {
383         struct kprobe *kp;
384 
385         list_for_each_entry_rcu(kp, &p->list, list) {
386                 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
387                         set_kprobe_instance(kp);
388                         kp->pre_handler(kp, regs);
389                 }
390                 reset_kprobe_instance();
391         }
392 }
393 
394 /* Free optimized instructions and optimized_kprobe */
395 static __kprobes void free_aggr_kprobe(struct kprobe *p)
396 {
397         struct optimized_kprobe *op;
398 
399         op = container_of(p, struct optimized_kprobe, kp);
400         arch_remove_optimized_kprobe(op);
401         arch_remove_kprobe(p);
402         kfree(op);
403 }
404 
405 /* Return true(!0) if the kprobe is ready for optimization. */
406 static inline int kprobe_optready(struct kprobe *p)
407 {
408         struct optimized_kprobe *op;
409 
410         if (kprobe_aggrprobe(p)) {
411                 op = container_of(p, struct optimized_kprobe, kp);
412                 return arch_prepared_optinsn(&op->optinsn);
413         }
414 
415         return 0;
416 }
417 
418 /* Return true(!0) if the kprobe is disarmed. Note: p must be on hash list */
419 static inline int kprobe_disarmed(struct kprobe *p)
420 {
421         struct optimized_kprobe *op;
422 
423         /* If kprobe is not aggr/opt probe, just return kprobe is disabled */
424         if (!kprobe_aggrprobe(p))
425                 return kprobe_disabled(p);
426 
427         op = container_of(p, struct optimized_kprobe, kp);
428 
429         return kprobe_disabled(p) && list_empty(&op->list);
430 }
431 
432 /* Return true(!0) if the probe is queued on (un)optimizing lists */
433 static int __kprobes kprobe_queued(struct kprobe *p)
434 {
435         struct optimized_kprobe *op;
436 
437         if (kprobe_aggrprobe(p)) {
438                 op = container_of(p, struct optimized_kprobe, kp);
439                 if (!list_empty(&op->list))
440                         return 1;
441         }
442         return 0;
443 }
444 
445 /*
446  * Return an optimized kprobe whose optimizing code replaces
447  * instructions including addr (exclude breakpoint).
448  */
449 static struct kprobe *__kprobes get_optimized_kprobe(unsigned long addr)
450 {
451         int i;
452         struct kprobe *p = NULL;
453         struct optimized_kprobe *op;
454 
455         /* Don't check i == 0, since that is a breakpoint case. */
456         for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH; i++)
457                 p = get_kprobe((void *)(addr - i));
458 
459         if (p && kprobe_optready(p)) {
460                 op = container_of(p, struct optimized_kprobe, kp);
461                 if (arch_within_optimized_kprobe(op, addr))
462                         return p;
463         }
464 
465         return NULL;
466 }
467 
468 /* Optimization staging list, protected by kprobe_mutex */
469 static LIST_HEAD(optimizing_list);
470 static LIST_HEAD(unoptimizing_list);
471 
472 static void kprobe_optimizer(struct work_struct *work);
473 static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
474 static DECLARE_COMPLETION(optimizer_comp);
475 #define OPTIMIZE_DELAY 5
476 
477 /*
478  * Optimize (replace a breakpoint with a jump) kprobes listed on
479  * optimizing_list.
480  */
481 static __kprobes void do_optimize_kprobes(void)
482 {
483         /* Optimization never be done when disarmed */
484         if (kprobes_all_disarmed || !kprobes_allow_optimization ||
485             list_empty(&optimizing_list))
486                 return;
487 
488         /*
489          * The optimization/unoptimization refers online_cpus via
490          * stop_machine() and cpu-hotplug modifies online_cpus.
491          * And same time, text_mutex will be held in cpu-hotplug and here.
492          * This combination can cause a deadlock (cpu-hotplug try to lock
493          * text_mutex but stop_machine can not be done because online_cpus
494          * has been changed)
495          * To avoid this deadlock, we need to call get_online_cpus()
496          * for preventing cpu-hotplug outside of text_mutex locking.
497          */
498         get_online_cpus();
499         mutex_lock(&text_mutex);
500         arch_optimize_kprobes(&optimizing_list);
501         mutex_unlock(&text_mutex);
502         put_online_cpus();
503 }
504 
505 /*
506  * Unoptimize (replace a jump with a breakpoint and remove the breakpoint
507  * if need) kprobes listed on unoptimizing_list.
508  */
509 static __kprobes void do_unoptimize_kprobes(struct list_head *free_list)
510 {
511         struct optimized_kprobe *op, *tmp;
512 
513         /* Unoptimization must be done anytime */
514         if (list_empty(&unoptimizing_list))
515                 return;
516 
517         /* Ditto to do_optimize_kprobes */
518         get_online_cpus();
519         mutex_lock(&text_mutex);
520         arch_unoptimize_kprobes(&unoptimizing_list, free_list);
521         /* Loop free_list for disarming */
522         list_for_each_entry_safe(op, tmp, free_list, list) {
523                 /* Disarm probes if marked disabled */
524                 if (kprobe_disabled(&op->kp))
525                         arch_disarm_kprobe(&op->kp);
526                 if (kprobe_unused(&op->kp)) {
527                         /*
528                          * Remove unused probes from hash list. After waiting
529                          * for synchronization, these probes are reclaimed.
530                          * (reclaiming is done by do_free_cleaned_kprobes.)
531                          */
532                         hlist_del_rcu(&op->kp.hlist);
533                 } else
534                         list_del_init(&op->list);
535         }
536         mutex_unlock(&text_mutex);
537         put_online_cpus();
538 }
539 
540 /* Reclaim all kprobes on the free_list */
541 static __kprobes void do_free_cleaned_kprobes(struct list_head *free_list)
542 {
543         struct optimized_kprobe *op, *tmp;
544 
545         list_for_each_entry_safe(op, tmp, free_list, list) {
546                 BUG_ON(!kprobe_unused(&op->kp));
547                 list_del_init(&op->list);
548                 free_aggr_kprobe(&op->kp);
549         }
550 }
551 
552 /* Start optimizer after OPTIMIZE_DELAY passed */
553 static __kprobes void kick_kprobe_optimizer(void)
554 {
555         if (!delayed_work_pending(&optimizing_work))
556                 schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
557 }
558 
559 /* Kprobe jump optimizer */
560 static __kprobes void kprobe_optimizer(struct work_struct *work)
561 {
562         LIST_HEAD(free_list);
563 
564         /* Lock modules while optimizing kprobes */
565         mutex_lock(&module_mutex);
566         mutex_lock(&kprobe_mutex);
567 
568         /*
569          * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
570          * kprobes before waiting for quiesence period.
571          */
572         do_unoptimize_kprobes(&free_list);
573 
574         /*
575          * Step 2: Wait for quiesence period to ensure all running interrupts
576          * are done. Because optprobe may modify multiple instructions
577          * there is a chance that Nth instruction is interrupted. In that
578          * case, running interrupt can return to 2nd-Nth byte of jump
579          * instruction. This wait is for avoiding it.
580          */
581         synchronize_sched();
582 
583         /* Step 3: Optimize kprobes after quiesence period */
584         do_optimize_kprobes();
585 
586         /* Step 4: Free cleaned kprobes after quiesence period */
587         do_free_cleaned_kprobes(&free_list);
588 
589         mutex_unlock(&kprobe_mutex);
590         mutex_unlock(&module_mutex);
591 
592         /* Step 5: Kick optimizer again if needed */
593         if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
594                 kick_kprobe_optimizer();
595         else
596                 /* Wake up all waiters */
597                 complete_all(&optimizer_comp);
598 }
599 
600 /* Wait for completing optimization and unoptimization */
601 static __kprobes void wait_for_kprobe_optimizer(void)
602 {
603         if (delayed_work_pending(&optimizing_work))
604                 wait_for_completion(&optimizer_comp);
605 }
606 
607 /* Optimize kprobe if p is ready to be optimized */
608 static __kprobes void optimize_kprobe(struct kprobe *p)
609 {
610         struct optimized_kprobe *op;
611 
612         /* Check if the kprobe is disabled or not ready for optimization. */
613         if (!kprobe_optready(p) || !kprobes_allow_optimization ||
614             (kprobe_disabled(p) || kprobes_all_disarmed))
615                 return;
616 
617         /* Both of break_handler and post_handler are not supported. */
618         if (p->break_handler || p->post_handler)
619                 return;
620 
621         op = container_of(p, struct optimized_kprobe, kp);
622 
623         /* Check there is no other kprobes at the optimized instructions */
624         if (arch_check_optimized_kprobe(op) < 0)
625                 return;
626 
627         /* Check if it is already optimized. */
628         if (op->kp.flags & KPROBE_FLAG_OPTIMIZED)
629                 return;
630         op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
631 
632         if (!list_empty(&op->list))
633                 /* This is under unoptimizing. Just dequeue the probe */
634                 list_del_init(&op->list);
635         else {
636                 list_add(&op->list, &optimizing_list);
637                 kick_kprobe_optimizer();
638         }
639 }
640 
641 /* Short cut to direct unoptimizing */
642 static __kprobes void force_unoptimize_kprobe(struct optimized_kprobe *op)
643 {
644         get_online_cpus();
645         arch_unoptimize_kprobe(op);
646         put_online_cpus();
647         if (kprobe_disabled(&op->kp))
648                 arch_disarm_kprobe(&op->kp);
649 }
650 
651 /* Unoptimize a kprobe if p is optimized */
652 static __kprobes void unoptimize_kprobe(struct kprobe *p, bool force)
653 {
654         struct optimized_kprobe *op;
655 
656         if (!kprobe_aggrprobe(p) || kprobe_disarmed(p))
657                 return; /* This is not an optprobe nor optimized */
658 
659         op = container_of(p, struct optimized_kprobe, kp);
660         if (!kprobe_optimized(p)) {
661                 /* Unoptimized or unoptimizing case */
662                 if (force && !list_empty(&op->list)) {
663                         /*
664                          * Only if this is unoptimizing kprobe and forced,
665                          * forcibly unoptimize it. (No need to unoptimize
666                          * unoptimized kprobe again :)
667                          */
668                         list_del_init(&op->list);
669                         force_unoptimize_kprobe(op);
670                 }
671                 return;
672         }
673 
674         op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
675         if (!list_empty(&op->list)) {
676                 /* Dequeue from the optimization queue */
677                 list_del_init(&op->list);
678                 return;
679         }
680         /* Optimized kprobe case */
681         if (force)
682                 /* Forcibly update the code: this is a special case */
683                 force_unoptimize_kprobe(op);
684         else {
685                 list_add(&op->list, &unoptimizing_list);
686                 kick_kprobe_optimizer();
687         }
688 }
689 
690 /* Cancel unoptimizing for reusing */
691 static void reuse_unused_kprobe(struct kprobe *ap)
692 {
693         struct optimized_kprobe *op;
694 
695         BUG_ON(!kprobe_unused(ap));
696         /*
697          * Unused kprobe MUST be on the way of delayed unoptimizing (means
698          * there is still a relative jump) and disabled.
699          */
700         op = container_of(ap, struct optimized_kprobe, kp);
701         if (unlikely(list_empty(&op->list)))
702                 printk(KERN_WARNING "Warning: found a stray unused "
703                         "aggrprobe@%p\n", ap->addr);
704         /* Enable the probe again */
705         ap->flags &= ~KPROBE_FLAG_DISABLED;
706         /* Optimize it again (remove from op->list) */
707         BUG_ON(!kprobe_optready(ap));
708         optimize_kprobe(ap);
709 }
710 
711 /* Remove optimized instructions */
712 static void __kprobes kill_optimized_kprobe(struct kprobe *p)
713 {
714         struct optimized_kprobe *op;
715 
716         op = container_of(p, struct optimized_kprobe, kp);
717         if (!list_empty(&op->list))
718                 /* Dequeue from the (un)optimization queue */
719                 list_del_init(&op->list);
720 
721         op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
722         /* Don't touch the code, because it is already freed. */
723         arch_remove_optimized_kprobe(op);
724 }
725 
726 /* Try to prepare optimized instructions */
727 static __kprobes void prepare_optimized_kprobe(struct kprobe *p)
728 {
729         struct optimized_kprobe *op;
730 
731         op = container_of(p, struct optimized_kprobe, kp);
732         arch_prepare_optimized_kprobe(op);
733 }
734 
735 /* Allocate new optimized_kprobe and try to prepare optimized instructions */
736 static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
737 {
738         struct optimized_kprobe *op;
739 
740         op = kzalloc(sizeof(struct optimized_kprobe), GFP_KERNEL);
741         if (!op)
742                 return NULL;
743 
744         INIT_LIST_HEAD(&op->list);
745         op->kp.addr = p->addr;
746         arch_prepare_optimized_kprobe(op);
747 
748         return &op->kp;
749 }
750 
751 static void __kprobes init_aggr_kprobe(struct kprobe *ap, struct kprobe *p);
752 
753 /*
754  * Prepare an optimized_kprobe and optimize it
755  * NOTE: p must be a normal registered kprobe
756  */
757 static __kprobes void try_to_optimize_kprobe(struct kprobe *p)
758 {
759         struct kprobe *ap;
760         struct optimized_kprobe *op;
761 
762         ap = alloc_aggr_kprobe(p);
763         if (!ap)
764                 return;
765 
766         op = container_of(ap, struct optimized_kprobe, kp);
767         if (!arch_prepared_optinsn(&op->optinsn)) {
768                 /* If failed to setup optimizing, fallback to kprobe */
769                 arch_remove_optimized_kprobe(op);
770                 kfree(op);
771                 return;
772         }
773 
774         init_aggr_kprobe(ap, p);
775         optimize_kprobe(ap);
776 }
777 
778 #ifdef CONFIG_SYSCTL
779 /* This should be called with kprobe_mutex locked */
780 static void __kprobes optimize_all_kprobes(void)
781 {
782         struct hlist_head *head;
783         struct hlist_node *node;
784         struct kprobe *p;
785         unsigned int i;
786 
787         /* If optimization is already allowed, just return */
788         if (kprobes_allow_optimization)
789                 return;
790 
791         kprobes_allow_optimization = true;
792         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
793                 head = &kprobe_table[i];
794                 hlist_for_each_entry_rcu(p, node, head, hlist)
795                         if (!kprobe_disabled(p))
796                                 optimize_kprobe(p);
797         }
798         printk(KERN_INFO "Kprobes globally optimized\n");
799 }
800 
801 /* This should be called with kprobe_mutex locked */
802 static void __kprobes unoptimize_all_kprobes(void)
803 {
804         struct hlist_head *head;
805         struct hlist_node *node;
806         struct kprobe *p;
807         unsigned int i;
808 
809         /* If optimization is already prohibited, just return */
810         if (!kprobes_allow_optimization)
811                 return;
812 
813         kprobes_allow_optimization = false;
814         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
815                 head = &kprobe_table[i];
816                 hlist_for_each_entry_rcu(p, node, head, hlist) {
817                         if (!kprobe_disabled(p))
818                                 unoptimize_kprobe(p, false);
819                 }
820         }
821         /* Wait for unoptimizing completion */
822         wait_for_kprobe_optimizer();
823         printk(KERN_INFO "Kprobes globally unoptimized\n");
824 }
825 
826 int sysctl_kprobes_optimization;
827 int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
828                                       void __user *buffer, size_t *length,
829                                       loff_t *ppos)
830 {
831         int ret;
832 
833         mutex_lock(&kprobe_mutex);
834         sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0;
835         ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
836 
837         if (sysctl_kprobes_optimization)
838                 optimize_all_kprobes();
839         else
840                 unoptimize_all_kprobes();
841         mutex_unlock(&kprobe_mutex);
842 
843         return ret;
844 }
845 #endif /* CONFIG_SYSCTL */
846 
847 /* Put a breakpoint for a probe. Must be called with text_mutex locked */
848 static void __kprobes __arm_kprobe(struct kprobe *p)
849 {
850         struct kprobe *_p;
851 
852         /* Check collision with other optimized kprobes */
853         _p = get_optimized_kprobe((unsigned long)p->addr);
854         if (unlikely(_p))
855                 /* Fallback to unoptimized kprobe */
856                 unoptimize_kprobe(_p, true);
857 
858         arch_arm_kprobe(p);
859         optimize_kprobe(p);     /* Try to optimize (add kprobe to a list) */
860 }
861 
862 /* Remove the breakpoint of a probe. Must be called with text_mutex locked */
863 static void __kprobes __disarm_kprobe(struct kprobe *p, bool reopt)
864 {
865         struct kprobe *_p;
866 
867         unoptimize_kprobe(p, false);    /* Try to unoptimize */
868 
869         if (!kprobe_queued(p)) {
870                 arch_disarm_kprobe(p);
871                 /* If another kprobe was blocked, optimize it. */
872                 _p = get_optimized_kprobe((unsigned long)p->addr);
873                 if (unlikely(_p) && reopt)
874                         optimize_kprobe(_p);
875         }
876         /* TODO: reoptimize others after unoptimized this probe */
877 }
878 
879 #else /* !CONFIG_OPTPROBES */
880 
881 #define optimize_kprobe(p)                      do {} while (0)
882 #define unoptimize_kprobe(p, f)                 do {} while (0)
883 #define kill_optimized_kprobe(p)                do {} while (0)
884 #define prepare_optimized_kprobe(p)             do {} while (0)
885 #define try_to_optimize_kprobe(p)               do {} while (0)
886 #define __arm_kprobe(p)                         arch_arm_kprobe(p)
887 #define __disarm_kprobe(p, o)                   arch_disarm_kprobe(p)
888 #define kprobe_disarmed(p)                      kprobe_disabled(p)
889 #define wait_for_kprobe_optimizer()             do {} while (0)
890 
891 /* There should be no unused kprobes can be reused without optimization */
892 static void reuse_unused_kprobe(struct kprobe *ap)
893 {
894         printk(KERN_ERR "Error: There should be no unused kprobe here.\n");
895         BUG_ON(kprobe_unused(ap));
896 }
897 
898 static __kprobes void free_aggr_kprobe(struct kprobe *p)
899 {
900         arch_remove_kprobe(p);
901         kfree(p);
902 }
903 
904 static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
905 {
906         return kzalloc(sizeof(struct kprobe), GFP_KERNEL);
907 }
908 #endif /* CONFIG_OPTPROBES */
909 
910 /* Arm a kprobe with text_mutex */
911 static void __kprobes arm_kprobe(struct kprobe *kp)
912 {
913         /*
914          * Here, since __arm_kprobe() doesn't use stop_machine(),
915          * this doesn't cause deadlock on text_mutex. So, we don't
916          * need get_online_cpus().
917          */
918         mutex_lock(&text_mutex);
919         __arm_kprobe(kp);
920         mutex_unlock(&text_mutex);
921 }
922 
923 /* Disarm a kprobe with text_mutex */
924 static void __kprobes disarm_kprobe(struct kprobe *kp)
925 {
926         /* Ditto */
927         mutex_lock(&text_mutex);
928         __disarm_kprobe(kp, true);
929         mutex_unlock(&text_mutex);
930 }
931 
932 /*
933  * Aggregate handlers for multiple kprobes support - these handlers
934  * take care of invoking the individual kprobe handlers on p->list
935  */
936 static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
937 {
938         struct kprobe *kp;
939 
940         list_for_each_entry_rcu(kp, &p->list, list) {
941                 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
942                         set_kprobe_instance(kp);
943                         if (kp->pre_handler(kp, regs))
944                                 return 1;
945                 }
946                 reset_kprobe_instance();
947         }
948         return 0;
949 }
950 
951 static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
952                                         unsigned long flags)
953 {
954         struct kprobe *kp;
955 
956         list_for_each_entry_rcu(kp, &p->list, list) {
957                 if (kp->post_handler && likely(!kprobe_disabled(kp))) {
958                         set_kprobe_instance(kp);
959                         kp->post_handler(kp, regs, flags);
960                         reset_kprobe_instance();
961                 }
962         }
963 }
964 
965 static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
966                                         int trapnr)
967 {
968         struct kprobe *cur = __this_cpu_read(kprobe_instance);
969 
970         /*
971          * if we faulted "during" the execution of a user specified
972          * probe handler, invoke just that probe's fault handler
973          */
974         if (cur && cur->fault_handler) {
975                 if (cur->fault_handler(cur, regs, trapnr))
976                         return 1;
977         }
978         return 0;
979 }
980 
981 static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
982 {
983         struct kprobe *cur = __this_cpu_read(kprobe_instance);
984         int ret = 0;
985 
986         if (cur && cur->break_handler) {
987                 if (cur->break_handler(cur, regs))
988                         ret = 1;
989         }
990         reset_kprobe_instance();
991         return ret;
992 }
993 
994 /* Walks the list and increments nmissed count for multiprobe case */
995 void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
996 {
997         struct kprobe *kp;
998         if (!kprobe_aggrprobe(p)) {
999                 p->nmissed++;
1000         } else {
1001                 list_for_each_entry_rcu(kp, &p->list, list)
1002                         kp->nmissed++;
1003         }
1004         return;
1005 }
1006 
1007 void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
1008                                 struct hlist_head *head)
1009 {
1010         struct kretprobe *rp = ri->rp;
1011 
1012         /* remove rp inst off the rprobe_inst_table */
1013         hlist_del(&ri->hlist);
1014         INIT_HLIST_NODE(&ri->hlist);
1015         if (likely(rp)) {
1016                 spin_lock(&rp->lock);
1017                 hlist_add_head(&ri->hlist, &rp->free_instances);
1018                 spin_unlock(&rp->lock);
1019         } else
1020                 /* Unregistering */
1021                 hlist_add_head(&ri->hlist, head);
1022 }
1023 
1024 void __kprobes kretprobe_hash_lock(struct task_struct *tsk,
1025                          struct hlist_head **head, unsigned long *flags)
1026 __acquires(hlist_lock)
1027 {
1028         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1029         spinlock_t *hlist_lock;
1030 
1031         *head = &kretprobe_inst_table[hash];
1032         hlist_lock = kretprobe_table_lock_ptr(hash);
1033         spin_lock_irqsave(hlist_lock, *flags);
1034 }
1035 
1036 static void __kprobes kretprobe_table_lock(unsigned long hash,
1037         unsigned long *flags)
1038 __acquires(hlist_lock)
1039 {
1040         spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1041         spin_lock_irqsave(hlist_lock, *flags);
1042 }
1043 
1044 void __kprobes kretprobe_hash_unlock(struct task_struct *tsk,
1045         unsigned long *flags)
1046 __releases(hlist_lock)
1047 {
1048         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1049         spinlock_t *hlist_lock;
1050 
1051         hlist_lock = kretprobe_table_lock_ptr(hash);
1052         spin_unlock_irqrestore(hlist_lock, *flags);
1053 }
1054 
1055 static void __kprobes kretprobe_table_unlock(unsigned long hash,
1056        unsigned long *flags)
1057 __releases(hlist_lock)
1058 {
1059         spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1060         spin_unlock_irqrestore(hlist_lock, *flags);
1061 }
1062 
1063 /*
1064  * This function is called from finish_task_switch when task tk becomes dead,
1065  * so that we can recycle any function-return probe instances associated
1066  * with this task. These left over instances represent probed functions
1067  * that have been called but will never return.
1068  */
1069 void __kprobes kprobe_flush_task(struct task_struct *tk)
1070 {
1071         struct kretprobe_instance *ri;
1072         struct hlist_head *head, empty_rp;
1073         struct hlist_node *node, *tmp;
1074         unsigned long hash, flags = 0;
1075 
1076         if (unlikely(!kprobes_initialized))
1077                 /* Early boot.  kretprobe_table_locks not yet initialized. */
1078                 return;
1079 
1080         INIT_HLIST_HEAD(&empty_rp);
1081         hash = hash_ptr(tk, KPROBE_HASH_BITS);
1082         head = &kretprobe_inst_table[hash];
1083         kretprobe_table_lock(hash, &flags);
1084         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
1085                 if (ri->task == tk)
1086                         recycle_rp_inst(ri, &empty_rp);
1087         }
1088         kretprobe_table_unlock(hash, &flags);
1089         hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
1090                 hlist_del(&ri->hlist);
1091                 kfree(ri);
1092         }
1093 }
1094 
1095 static inline void free_rp_inst(struct kretprobe *rp)
1096 {
1097         struct kretprobe_instance *ri;
1098         struct hlist_node *pos, *next;
1099 
1100         hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, hlist) {
1101                 hlist_del(&ri->hlist);
1102                 kfree(ri);
1103         }
1104 }
1105 
1106 static void __kprobes cleanup_rp_inst(struct kretprobe *rp)
1107 {
1108         unsigned long flags, hash;
1109         struct kretprobe_instance *ri;
1110         struct hlist_node *pos, *next;
1111         struct hlist_head *head;
1112 
1113         /* No race here */
1114         for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
1115                 kretprobe_table_lock(hash, &flags);
1116                 head = &kretprobe_inst_table[hash];
1117                 hlist_for_each_entry_safe(ri, pos, next, head, hlist) {
1118                         if (ri->rp == rp)
1119                                 ri->rp = NULL;
1120                 }
1121                 kretprobe_table_unlock(hash, &flags);
1122         }
1123         free_rp_inst(rp);
1124 }
1125 
1126 /*
1127 * Add the new probe to ap->list. Fail if this is the
1128 * second jprobe at the address - two jprobes can't coexist
1129 */
1130 static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p)
1131 {
1132         BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
1133 
1134         if (p->break_handler || p->post_handler)
1135                 unoptimize_kprobe(ap, true);    /* Fall back to normal kprobe */
1136 
1137         if (p->break_handler) {
1138                 if (ap->break_handler)
1139                         return -EEXIST;
1140                 list_add_tail_rcu(&p->list, &ap->list);
1141                 ap->break_handler = aggr_break_handler;
1142         } else
1143                 list_add_rcu(&p->list, &ap->list);
1144         if (p->post_handler && !ap->post_handler)
1145                 ap->post_handler = aggr_post_handler;
1146 
1147         if (kprobe_disabled(ap) && !kprobe_disabled(p)) {
1148                 ap->flags &= ~KPROBE_FLAG_DISABLED;
1149                 if (!kprobes_all_disarmed)
1150                         /* Arm the breakpoint again. */
1151                         __arm_kprobe(ap);
1152         }
1153         return 0;
1154 }
1155 
1156 /*
1157  * Fill in the required fields of the "manager kprobe". Replace the
1158  * earlier kprobe in the hlist with the manager kprobe
1159  */
1160 static void __kprobes init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
1161 {
1162         /* Copy p's insn slot to ap */
1163         copy_kprobe(p, ap);
1164         flush_insn_slot(ap);
1165         ap->addr = p->addr;
1166         ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED;
1167         ap->pre_handler = aggr_pre_handler;
1168         ap->fault_handler = aggr_fault_handler;
1169         /* We don't care the kprobe which has gone. */
1170         if (p->post_handler && !kprobe_gone(p))
1171                 ap->post_handler = aggr_post_handler;
1172         if (p->break_handler && !kprobe_gone(p))
1173                 ap->break_handler = aggr_break_handler;
1174 
1175         INIT_LIST_HEAD(&ap->list);
1176         INIT_HLIST_NODE(&ap->hlist);
1177 
1178         list_add_rcu(&p->list, &ap->list);
1179         hlist_replace_rcu(&p->hlist, &ap->hlist);
1180 }
1181 
1182 /*
1183  * This is the second or subsequent kprobe at the address - handle
1184  * the intricacies
1185  */
1186 static int __kprobes register_aggr_kprobe(struct kprobe *orig_p,
1187                                           struct kprobe *p)
1188 {
1189         int ret = 0;
1190         struct kprobe *ap = orig_p;
1191 
1192         if (!kprobe_aggrprobe(orig_p)) {
1193                 /* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */
1194                 ap = alloc_aggr_kprobe(orig_p);
1195                 if (!ap)
1196                         return -ENOMEM;
1197                 init_aggr_kprobe(ap, orig_p);
1198         } else if (kprobe_unused(ap))
1199                 /* This probe is going to die. Rescue it */
1200                 reuse_unused_kprobe(ap);
1201 
1202         if (kprobe_gone(ap)) {
1203                 /*
1204                  * Attempting to insert new probe at the same location that
1205                  * had a probe in the module vaddr area which already
1206                  * freed. So, the instruction slot has already been
1207                  * released. We need a new slot for the new probe.
1208                  */
1209                 ret = arch_prepare_kprobe(ap);
1210                 if (ret)
1211                         /*
1212                          * Even if fail to allocate new slot, don't need to
1213                          * free aggr_probe. It will be used next time, or
1214                          * freed by unregister_kprobe.
1215                          */
1216                         return ret;
1217 
1218                 /* Prepare optimized instructions if possible. */
1219                 prepare_optimized_kprobe(ap);
1220 
1221                 /*
1222                  * Clear gone flag to prevent allocating new slot again, and
1223                  * set disabled flag because it is not armed yet.
1224                  */
1225                 ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
1226                             | KPROBE_FLAG_DISABLED;
1227         }
1228 
1229         /* Copy ap's insn slot to p */
1230         copy_kprobe(ap, p);
1231         return add_new_kprobe(ap, p);
1232 }
1233 
1234 static int __kprobes in_kprobes_functions(unsigned long addr)
1235 {
1236         struct kprobe_blackpoint *kb;
1237 
1238         if (addr >= (unsigned long)__kprobes_text_start &&
1239             addr < (unsigned long)__kprobes_text_end)
1240                 return -EINVAL;
1241         /*
1242          * If there exists a kprobe_blacklist, verify and
1243          * fail any probe registration in the prohibited area
1244          */
1245         for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
1246                 if (kb->start_addr) {
1247                         if (addr >= kb->start_addr &&
1248                             addr < (kb->start_addr + kb->range))
1249                                 return -EINVAL;
1250                 }
1251         }
1252         return 0;
1253 }
1254 
1255 /*
1256  * If we have a symbol_name argument, look it up and add the offset field
1257  * to it. This way, we can specify a relative address to a symbol.
1258  */
1259 static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p)
1260 {
1261         kprobe_opcode_t *addr = p->addr;
1262         if (p->symbol_name) {
1263                 if (addr)
1264                         return NULL;
1265                 kprobe_lookup_name(p->symbol_name, addr);
1266         }
1267 
1268         if (!addr)
1269                 return NULL;
1270         return (kprobe_opcode_t *)(((char *)addr) + p->offset);
1271 }
1272 
1273 /* Check passed kprobe is valid and return kprobe in kprobe_table. */
1274 static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p)
1275 {
1276         struct kprobe *ap, *list_p;
1277 
1278         ap = get_kprobe(p->addr);
1279         if (unlikely(!ap))
1280                 return NULL;
1281 
1282         if (p != ap) {
1283                 list_for_each_entry_rcu(list_p, &ap->list, list)
1284                         if (list_p == p)
1285                         /* kprobe p is a valid probe */
1286                                 goto valid;
1287                 return NULL;
1288         }
1289 valid:
1290         return ap;
1291 }
1292 
1293 /* Return error if the kprobe is being re-registered */
1294 static inline int check_kprobe_rereg(struct kprobe *p)
1295 {
1296         int ret = 0;
1297 
1298         mutex_lock(&kprobe_mutex);
1299         if (__get_valid_kprobe(p))
1300                 ret = -EINVAL;
1301         mutex_unlock(&kprobe_mutex);
1302 
1303         return ret;
1304 }
1305 
1306 int __kprobes register_kprobe(struct kprobe *p)
1307 {
1308         int ret = 0;
1309         struct kprobe *old_p;
1310         struct module *probed_mod;
1311         kprobe_opcode_t *addr;
1312 
1313         addr = kprobe_addr(p);
1314         if (!addr)
1315                 return -EINVAL;
1316         p->addr = addr;
1317 
1318         ret = check_kprobe_rereg(p);
1319         if (ret)
1320                 return ret;
1321 
1322         jump_label_lock();
1323         preempt_disable();
1324         if (!kernel_text_address((unsigned long) p->addr) ||
1325             in_kprobes_functions((unsigned long) p->addr) ||
1326             ftrace_text_reserved(p->addr, p->addr) ||
1327             jump_label_text_reserved(p->addr, p->addr))
1328                 goto fail_with_jump_label;
1329 
1330         /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
1331         p->flags &= KPROBE_FLAG_DISABLED;
1332 
1333         /*
1334          * Check if are we probing a module.
1335          */
1336         probed_mod = __module_text_address((unsigned long) p->addr);
1337         if (probed_mod) {
1338                 /*
1339                  * We must hold a refcount of the probed module while updating
1340                  * its code to prohibit unexpected unloading.
1341                  */
1342                 if (unlikely(!try_module_get(probed_mod)))
1343                         goto fail_with_jump_label;
1344 
1345                 /*
1346                  * If the module freed .init.text, we couldn't insert
1347                  * kprobes in there.
1348                  */
1349                 if (within_module_init((unsigned long)p->addr, probed_mod) &&
1350                     probed_mod->state != MODULE_STATE_COMING) {
1351                         module_put(probed_mod);
1352                         goto fail_with_jump_label;
1353                 }
1354         }
1355         preempt_enable();
1356         jump_label_unlock();
1357 
1358         p->nmissed = 0;
1359         INIT_LIST_HEAD(&p->list);
1360         mutex_lock(&kprobe_mutex);
1361 
1362         jump_label_lock(); /* needed to call jump_label_text_reserved() */
1363 
1364         get_online_cpus();      /* For avoiding text_mutex deadlock. */
1365         mutex_lock(&text_mutex);
1366 
1367         old_p = get_kprobe(p->addr);
1368         if (old_p) {
1369                 /* Since this may unoptimize old_p, locking text_mutex. */
1370                 ret = register_aggr_kprobe(old_p, p);
1371                 goto out;
1372         }
1373 
1374         ret = arch_prepare_kprobe(p);
1375         if (ret)
1376                 goto out;
1377 
1378         INIT_HLIST_NODE(&p->hlist);
1379         hlist_add_head_rcu(&p->hlist,
1380                        &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
1381 
1382         if (!kprobes_all_disarmed && !kprobe_disabled(p))
1383                 __arm_kprobe(p);
1384 
1385         /* Try to optimize kprobe */
1386         try_to_optimize_kprobe(p);
1387 
1388 out:
1389         mutex_unlock(&text_mutex);
1390         put_online_cpus();
1391         jump_label_unlock();
1392         mutex_unlock(&kprobe_mutex);
1393 
1394         if (probed_mod)
1395                 module_put(probed_mod);
1396 
1397         return ret;
1398 
1399 fail_with_jump_label:
1400         preempt_enable();
1401         jump_label_unlock();
1402         return -EINVAL;
1403 }
1404 EXPORT_SYMBOL_GPL(register_kprobe);
1405 
1406 /* Check if all probes on the aggrprobe are disabled */
1407 static int __kprobes aggr_kprobe_disabled(struct kprobe *ap)
1408 {
1409         struct kprobe *kp;
1410 
1411         list_for_each_entry_rcu(kp, &ap->list, list)
1412                 if (!kprobe_disabled(kp))
1413                         /*
1414                          * There is an active probe on the list.
1415                          * We can't disable this ap.
1416                          */
1417                         return 0;
1418 
1419         return 1;
1420 }
1421 
1422 /* Disable one kprobe: Make sure called under kprobe_mutex is locked */
1423 static struct kprobe *__kprobes __disable_kprobe(struct kprobe *p)
1424 {
1425         struct kprobe *orig_p;
1426 
1427         /* Get an original kprobe for return */
1428         orig_p = __get_valid_kprobe(p);
1429         if (unlikely(orig_p == NULL))
1430                 return NULL;
1431 
1432         if (!kprobe_disabled(p)) {
1433                 /* Disable probe if it is a child probe */
1434                 if (p != orig_p)
1435                         p->flags |= KPROBE_FLAG_DISABLED;
1436 
1437                 /* Try to disarm and disable this/parent probe */
1438                 if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
1439                         disarm_kprobe(orig_p);
1440                         orig_p->flags |= KPROBE_FLAG_DISABLED;
1441                 }
1442         }
1443 
1444         return orig_p;
1445 }
1446 
1447 /*
1448  * Unregister a kprobe without a scheduler synchronization.
1449  */
1450 static int __kprobes __unregister_kprobe_top(struct kprobe *p)
1451 {
1452         struct kprobe *ap, *list_p;
1453 
1454         /* Disable kprobe. This will disarm it if needed. */
1455         ap = __disable_kprobe(p);
1456         if (ap == NULL)
1457                 return -EINVAL;
1458 
1459         if (ap == p)
1460                 /*
1461                  * This probe is an independent(and non-optimized) kprobe
1462                  * (not an aggrprobe). Remove from the hash list.
1463                  */
1464                 goto disarmed;
1465 
1466         /* Following process expects this probe is an aggrprobe */
1467         WARN_ON(!kprobe_aggrprobe(ap));
1468 
1469         if (list_is_singular(&ap->list) && kprobe_disarmed(ap))
1470                 /*
1471                  * !disarmed could be happen if the probe is under delayed
1472                  * unoptimizing.
1473                  */
1474                 goto disarmed;
1475         else {
1476                 /* If disabling probe has special handlers, update aggrprobe */
1477                 if (p->break_handler && !kprobe_gone(p))
1478                         ap->break_handler = NULL;
1479                 if (p->post_handler && !kprobe_gone(p)) {
1480                         list_for_each_entry_rcu(list_p, &ap->list, list) {
1481                                 if ((list_p != p) && (list_p->post_handler))
1482                                         goto noclean;
1483                         }
1484                         ap->post_handler = NULL;
1485                 }
1486 noclean:
1487                 /*
1488                  * Remove from the aggrprobe: this path will do nothing in
1489                  * __unregister_kprobe_bottom().
1490                  */
1491                 list_del_rcu(&p->list);
1492                 if (!kprobe_disabled(ap) && !kprobes_all_disarmed)
1493                         /*
1494                          * Try to optimize this probe again, because post
1495                          * handler may have been changed.
1496                          */
1497                         optimize_kprobe(ap);
1498         }
1499         return 0;
1500 
1501 disarmed:
1502         BUG_ON(!kprobe_disarmed(ap));
1503         hlist_del_rcu(&ap->hlist);
1504         return 0;
1505 }
1506 
1507 static void __kprobes __unregister_kprobe_bottom(struct kprobe *p)
1508 {
1509         struct kprobe *ap;
1510 
1511         if (list_empty(&p->list))
1512                 /* This is an independent kprobe */
1513                 arch_remove_kprobe(p);
1514         else if (list_is_singular(&p->list)) {
1515                 /* This is the last child of an aggrprobe */
1516                 ap = list_entry(p->list.next, struct kprobe, list);
1517                 list_del(&p->list);
1518                 free_aggr_kprobe(ap);
1519         }
1520         /* Otherwise, do nothing. */
1521 }
1522 
1523 int __kprobes register_kprobes(struct kprobe **kps, int num)
1524 {
1525         int i, ret = 0;
1526 
1527         if (num <= 0)
1528                 return -EINVAL;
1529         for (i = 0; i < num; i++) {
1530                 ret = register_kprobe(kps[i]);
1531                 if (ret < 0) {
1532                         if (i > 0)
1533                                 unregister_kprobes(kps, i);
1534                         break;
1535                 }
1536         }
1537         return ret;
1538 }
1539 EXPORT_SYMBOL_GPL(register_kprobes);
1540 
1541 void __kprobes unregister_kprobe(struct kprobe *p)
1542 {
1543         unregister_kprobes(&p, 1);
1544 }
1545 EXPORT_SYMBOL_GPL(unregister_kprobe);
1546 
1547 void __kprobes unregister_kprobes(struct kprobe **kps, int num)
1548 {
1549         int i;
1550 
1551         if (num <= 0)
1552                 return;
1553         mutex_lock(&kprobe_mutex);
1554         for (i = 0; i < num; i++)
1555                 if (__unregister_kprobe_top(kps[i]) < 0)
1556                         kps[i]->addr = NULL;
1557         mutex_unlock(&kprobe_mutex);
1558 
1559         synchronize_sched();
1560         for (i = 0; i < num; i++)
1561                 if (kps[i]->addr)
1562                         __unregister_kprobe_bottom(kps[i]);
1563 }
1564 EXPORT_SYMBOL_GPL(unregister_kprobes);
1565 
1566 static struct notifier_block kprobe_exceptions_nb = {
1567         .notifier_call = kprobe_exceptions_notify,
1568         .priority = 0x7fffffff /* we need to be notified first */
1569 };
1570 
1571 unsigned long __weak arch_deref_entry_point(void *entry)
1572 {
1573         return (unsigned long)entry;
1574 }
1575 
1576 int __kprobes register_jprobes(struct jprobe **jps, int num)
1577 {
1578         struct jprobe *jp;
1579         int ret = 0, i;
1580 
1581         if (num <= 0)
1582                 return -EINVAL;
1583         for (i = 0; i < num; i++) {
1584                 unsigned long addr, offset;
1585                 jp = jps[i];
1586                 addr = arch_deref_entry_point(jp->entry);
1587 
1588                 /* Verify probepoint is a function entry point */
1589                 if (kallsyms_lookup_size_offset(addr, NULL, &offset) &&
1590                     offset == 0) {
1591                         jp->kp.pre_handler = setjmp_pre_handler;
1592                         jp->kp.break_handler = longjmp_break_handler;
1593                         ret = register_kprobe(&jp->kp);
1594                 } else
1595                         ret = -EINVAL;
1596 
1597                 if (ret < 0) {
1598                         if (i > 0)
1599                                 unregister_jprobes(jps, i);
1600                         break;
1601                 }
1602         }
1603         return ret;
1604 }
1605 EXPORT_SYMBOL_GPL(register_jprobes);
1606 
1607 int __kprobes register_jprobe(struct jprobe *jp)
1608 {
1609         return register_jprobes(&jp, 1);
1610 }
1611 EXPORT_SYMBOL_GPL(register_jprobe);
1612 
1613 void __kprobes unregister_jprobe(struct jprobe *jp)
1614 {
1615         unregister_jprobes(&jp, 1);
1616 }
1617 EXPORT_SYMBOL_GPL(unregister_jprobe);
1618 
1619 void __kprobes unregister_jprobes(struct jprobe **jps, int num)
1620 {
1621         int i;
1622 
1623         if (num <= 0)
1624                 return;
1625         mutex_lock(&kprobe_mutex);
1626         for (i = 0; i < num; i++)
1627                 if (__unregister_kprobe_top(&jps[i]->kp) < 0)
1628                         jps[i]->kp.addr = NULL;
1629         mutex_unlock(&kprobe_mutex);
1630 
1631         synchronize_sched();
1632         for (i = 0; i < num; i++) {
1633                 if (jps[i]->kp.addr)
1634                         __unregister_kprobe_bottom(&jps[i]->kp);
1635         }
1636 }
1637 EXPORT_SYMBOL_GPL(unregister_jprobes);
1638 
1639 #ifdef CONFIG_KRETPROBES
1640 /*
1641  * This kprobe pre_handler is registered with every kretprobe. When probe
1642  * hits it will set up the return probe.
1643  */
1644 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
1645                                            struct pt_regs *regs)
1646 {
1647         struct kretprobe *rp = container_of(p, struct kretprobe, kp);
1648         unsigned long hash, flags = 0;
1649         struct kretprobe_instance *ri;
1650 
1651         /*TODO: consider to only swap the RA after the last pre_handler fired */
1652         hash = hash_ptr(current, KPROBE_HASH_BITS);
1653         spin_lock_irqsave(&rp->lock, flags);
1654         if (!hlist_empty(&rp->free_instances)) {
1655                 ri = hlist_entry(rp->free_instances.first,
1656                                 struct kretprobe_instance, hlist);
1657                 hlist_del(&ri->hlist);
1658                 spin_unlock_irqrestore(&rp->lock, flags);
1659 
1660                 ri->rp = rp;
1661                 ri->task = current;
1662 
1663                 if (rp->entry_handler && rp->entry_handler(ri, regs)) {
1664                         spin_lock_irqsave(&rp->lock, flags);
1665                         hlist_add_head(&ri->hlist, &rp->free_instances);
1666                         spin_unlock_irqrestore(&rp->lock, flags);
1667                         return 0;
1668                 }
1669 
1670                 arch_prepare_kretprobe(ri, regs);
1671 
1672                 /* XXX(hch): why is there no hlist_move_head? */
1673                 INIT_HLIST_NODE(&ri->hlist);
1674                 kretprobe_table_lock(hash, &flags);
1675                 hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
1676                 kretprobe_table_unlock(hash, &flags);
1677         } else {
1678                 rp->nmissed++;
1679                 spin_unlock_irqrestore(&rp->lock, flags);
1680         }
1681         return 0;
1682 }
1683 
1684 int __kprobes register_kretprobe(struct kretprobe *rp)
1685 {
1686         int ret = 0;
1687         struct kretprobe_instance *inst;
1688         int i;
1689         void *addr;
1690 
1691         if (kretprobe_blacklist_size) {
1692                 addr = kprobe_addr(&rp->kp);
1693                 if (!addr)
1694                         return -EINVAL;
1695 
1696                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1697                         if (kretprobe_blacklist[i].addr == addr)
1698                                 return -EINVAL;
1699                 }
1700         }
1701 
1702         rp->kp.pre_handler = pre_handler_kretprobe;
1703         rp->kp.post_handler = NULL;
1704         rp->kp.fault_handler = NULL;
1705         rp->kp.break_handler = NULL;
1706 
1707         /* Pre-allocate memory for max kretprobe instances */
1708         if (rp->maxactive <= 0) {
1709 #ifdef CONFIG_PREEMPT
1710                 rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
1711 #else
1712                 rp->maxactive = num_possible_cpus();
1713 #endif
1714         }
1715         spin_lock_init(&rp->lock);
1716         INIT_HLIST_HEAD(&rp->free_instances);
1717         for (i = 0; i < rp->maxactive; i++) {
1718                 inst = kmalloc(sizeof(struct kretprobe_instance) +
1719                                rp->data_size, GFP_KERNEL);
1720                 if (inst == NULL) {
1721                         free_rp_inst(rp);
1722                         return -ENOMEM;
1723                 }
1724                 INIT_HLIST_NODE(&inst->hlist);
1725                 hlist_add_head(&inst->hlist, &rp->free_instances);
1726         }
1727 
1728         rp->nmissed = 0;
1729         /* Establish function entry probe point */
1730         ret = register_kprobe(&rp->kp);
1731         if (ret != 0)
1732                 free_rp_inst(rp);
1733         return ret;
1734 }
1735 EXPORT_SYMBOL_GPL(register_kretprobe);
1736 
1737 int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1738 {
1739         int ret = 0, i;
1740 
1741         if (num <= 0)
1742                 return -EINVAL;
1743         for (i = 0; i < num; i++) {
1744                 ret = register_kretprobe(rps[i]);
1745                 if (ret < 0) {
1746                         if (i > 0)
1747                                 unregister_kretprobes(rps, i);
1748                         break;
1749                 }
1750         }
1751         return ret;
1752 }
1753 EXPORT_SYMBOL_GPL(register_kretprobes);
1754 
1755 void __kprobes unregister_kretprobe(struct kretprobe *rp)
1756 {
1757         unregister_kretprobes(&rp, 1);
1758 }
1759 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1760 
1761 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1762 {
1763         int i;
1764 
1765         if (num <= 0)
1766                 return;
1767         mutex_lock(&kprobe_mutex);
1768         for (i = 0; i < num; i++)
1769                 if (__unregister_kprobe_top(&rps[i]->kp) < 0)
1770                         rps[i]->kp.addr = NULL;
1771         mutex_unlock(&kprobe_mutex);
1772 
1773         synchronize_sched();
1774         for (i = 0; i < num; i++) {
1775                 if (rps[i]->kp.addr) {
1776                         __unregister_kprobe_bottom(&rps[i]->kp);
1777                         cleanup_rp_inst(rps[i]);
1778                 }
1779         }
1780 }
1781 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1782 
1783 #else /* CONFIG_KRETPROBES */
1784 int __kprobes register_kretprobe(struct kretprobe *rp)
1785 {
1786         return -ENOSYS;
1787 }
1788 EXPORT_SYMBOL_GPL(register_kretprobe);
1789 
1790 int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1791 {
1792         return -ENOSYS;
1793 }
1794 EXPORT_SYMBOL_GPL(register_kretprobes);
1795 
1796 void __kprobes unregister_kretprobe(struct kretprobe *rp)
1797 {
1798 }
1799 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1800 
1801 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1802 {
1803 }
1804 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1805 
1806 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
1807                                            struct pt_regs *regs)
1808 {
1809         return 0;
1810 }
1811 
1812 #endif /* CONFIG_KRETPROBES */
1813 
1814 /* Set the kprobe gone and remove its instruction buffer. */
1815 static void __kprobes kill_kprobe(struct kprobe *p)
1816 {
1817         struct kprobe *kp;
1818 
1819         p->flags |= KPROBE_FLAG_GONE;
1820         if (kprobe_aggrprobe(p)) {
1821                 /*
1822                  * If this is an aggr_kprobe, we have to list all the
1823                  * chained probes and mark them GONE.
1824                  */
1825                 list_for_each_entry_rcu(kp, &p->list, list)
1826                         kp->flags |= KPROBE_FLAG_GONE;
1827                 p->post_handler = NULL;
1828                 p->break_handler = NULL;
1829                 kill_optimized_kprobe(p);
1830         }
1831         /*
1832          * Here, we can remove insn_slot safely, because no thread calls
1833          * the original probed function (which will be freed soon) any more.
1834          */
1835         arch_remove_kprobe(p);
1836 }
1837 
1838 /* Disable one kprobe */
1839 int __kprobes disable_kprobe(struct kprobe *kp)
1840 {
1841         int ret = 0;
1842 
1843         mutex_lock(&kprobe_mutex);
1844 
1845         /* Disable this kprobe */
1846         if (__disable_kprobe(kp) == NULL)
1847                 ret = -EINVAL;
1848 
1849         mutex_unlock(&kprobe_mutex);
1850         return ret;
1851 }
1852 EXPORT_SYMBOL_GPL(disable_kprobe);
1853 
1854 /* Enable one kprobe */
1855 int __kprobes enable_kprobe(struct kprobe *kp)
1856 {
1857         int ret = 0;
1858         struct kprobe *p;
1859 
1860         mutex_lock(&kprobe_mutex);
1861 
1862         /* Check whether specified probe is valid. */
1863         p = __get_valid_kprobe(kp);
1864         if (unlikely(p == NULL)) {
1865                 ret = -EINVAL;
1866                 goto out;
1867         }
1868 
1869         if (kprobe_gone(kp)) {
1870                 /* This kprobe has gone, we couldn't enable it. */
1871                 ret = -EINVAL;
1872                 goto out;
1873         }
1874 
1875         if (p != kp)
1876                 kp->flags &= ~KPROBE_FLAG_DISABLED;
1877 
1878         if (!kprobes_all_disarmed && kprobe_disabled(p)) {
1879                 p->flags &= ~KPROBE_FLAG_DISABLED;
1880                 arm_kprobe(p);
1881         }
1882 out:
1883         mutex_unlock(&kprobe_mutex);
1884         return ret;
1885 }
1886 EXPORT_SYMBOL_GPL(enable_kprobe);
1887 
1888 void __kprobes dump_kprobe(struct kprobe *kp)
1889 {
1890         printk(KERN_WARNING "Dumping kprobe:\n");
1891         printk(KERN_WARNING "Name: %s\nAddress: %p\nOffset: %x\n",
1892                kp->symbol_name, kp->addr, kp->offset);
1893 }
1894 
1895 /* Module notifier call back, checking kprobes on the module */
1896 static int __kprobes kprobes_module_callback(struct notifier_block *nb,
1897                                              unsigned long val, void *data)
1898 {
1899         struct module *mod = data;
1900         struct hlist_head *head;
1901         struct hlist_node *node;
1902         struct kprobe *p;
1903         unsigned int i;
1904         int checkcore = (val == MODULE_STATE_GOING);
1905 
1906         if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
1907                 return NOTIFY_DONE;
1908 
1909         /*
1910          * When MODULE_STATE_GOING was notified, both of module .text and
1911          * .init.text sections would be freed. When MODULE_STATE_LIVE was
1912          * notified, only .init.text section would be freed. We need to
1913          * disable kprobes which have been inserted in the sections.
1914          */
1915         mutex_lock(&kprobe_mutex);
1916         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1917                 head = &kprobe_table[i];
1918                 hlist_for_each_entry_rcu(p, node, head, hlist)
1919                         if (within_module_init((unsigned long)p->addr, mod) ||
1920                             (checkcore &&
1921                              within_module_core((unsigned long)p->addr, mod))) {
1922                                 /*
1923                                  * The vaddr this probe is installed will soon
1924                                  * be vfreed buy not synced to disk. Hence,
1925                                  * disarming the breakpoint isn't needed.
1926                                  */
1927                                 kill_kprobe(p);
1928                         }
1929         }
1930         mutex_unlock(&kprobe_mutex);
1931         return NOTIFY_DONE;
1932 }
1933 
1934 static struct notifier_block kprobe_module_nb = {
1935         .notifier_call = kprobes_module_callback,
1936         .priority = 0
1937 };
1938 
1939 static int __init init_kprobes(void)
1940 {
1941         int i, err = 0;
1942         unsigned long offset = 0, size = 0;
1943         char *modname, namebuf[128];
1944         const char *symbol_name;
1945         void *addr;
1946         struct kprobe_blackpoint *kb;
1947 
1948         /* FIXME allocate the probe table, currently defined statically */
1949         /* initialize all list heads */
1950         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1951                 INIT_HLIST_HEAD(&kprobe_table[i]);
1952                 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
1953                 spin_lock_init(&(kretprobe_table_locks[i].lock));
1954         }
1955 
1956         /*
1957          * Lookup and populate the kprobe_blacklist.
1958          *
1959          * Unlike the kretprobe blacklist, we'll need to determine
1960          * the range of addresses that belong to the said functions,
1961          * since a kprobe need not necessarily be at the beginning
1962          * of a function.
1963          */
1964         for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
1965                 kprobe_lookup_name(kb->name, addr);
1966                 if (!addr)
1967                         continue;
1968 
1969                 kb->start_addr = (unsigned long)addr;
1970                 symbol_name = kallsyms_lookup(kb->start_addr,
1971                                 &size, &offset, &modname, namebuf);
1972                 if (!symbol_name)
1973                         kb->range = 0;
1974                 else
1975                         kb->range = size;
1976         }
1977 
1978         if (kretprobe_blacklist_size) {
1979                 /* lookup the function address from its name */
1980                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1981                         kprobe_lookup_name(kretprobe_blacklist[i].name,
1982                                            kretprobe_blacklist[i].addr);
1983                         if (!kretprobe_blacklist[i].addr)
1984                                 printk("kretprobe: lookup failed: %s\n",
1985                                        kretprobe_blacklist[i].name);
1986                 }
1987         }
1988 
1989 #if defined(CONFIG_OPTPROBES)
1990 #if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
1991         /* Init kprobe_optinsn_slots */
1992         kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
1993 #endif
1994         /* By default, kprobes can be optimized */
1995         kprobes_allow_optimization = true;
1996 #endif
1997 
1998         /* By default, kprobes are armed */
1999         kprobes_all_disarmed = false;
2000 
2001         err = arch_init_kprobes();
2002         if (!err)
2003                 err = register_die_notifier(&kprobe_exceptions_nb);
2004         if (!err)
2005                 err = register_module_notifier(&kprobe_module_nb);
2006 
2007         kprobes_initialized = (err == 0);
2008 
2009         if (!err)
2010                 init_test_probes();
2011         return err;
2012 }
2013 
2014 #ifdef CONFIG_DEBUG_FS
2015 static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
2016                 const char *sym, int offset, char *modname, struct kprobe *pp)
2017 {
2018         char *kprobe_type;
2019 
2020         if (p->pre_handler == pre_handler_kretprobe)
2021                 kprobe_type = "r";
2022         else if (p->pre_handler == setjmp_pre_handler)
2023                 kprobe_type = "j";
2024         else
2025                 kprobe_type = "k";
2026 
2027         if (sym)
2028                 seq_printf(pi, "%p  %s  %s+0x%x  %s ",
2029                         p->addr, kprobe_type, sym, offset,
2030                         (modname ? modname : " "));
2031         else
2032                 seq_printf(pi, "%p  %s  %p ",
2033                         p->addr, kprobe_type, p->addr);
2034 
2035         if (!pp)
2036                 pp = p;
2037         seq_printf(pi, "%s%s%s\n",
2038                 (kprobe_gone(p) ? "[GONE]" : ""),
2039                 ((kprobe_disabled(p) && !kprobe_gone(p)) ?  "[DISABLED]" : ""),
2040                 (kprobe_optimized(pp) ? "[OPTIMIZED]" : ""));
2041 }
2042 
2043 static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
2044 {
2045         return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
2046 }
2047 
2048 static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
2049 {
2050         (*pos)++;
2051         if (*pos >= KPROBE_TABLE_SIZE)
2052                 return NULL;
2053         return pos;
2054 }
2055 
2056 static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v)
2057 {
2058         /* Nothing to do */
2059 }
2060 
2061 static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v)
2062 {
2063         struct hlist_head *head;
2064         struct hlist_node *node;
2065         struct kprobe *p, *kp;
2066         const char *sym = NULL;
2067         unsigned int i = *(loff_t *) v;
2068         unsigned long offset = 0;
2069         char *modname, namebuf[128];
2070 
2071         head = &kprobe_table[i];
2072         preempt_disable();
2073         hlist_for_each_entry_rcu(p, node, head, hlist) {
2074                 sym = kallsyms_lookup((unsigned long)p->addr, NULL,
2075                                         &offset, &modname, namebuf);
2076                 if (kprobe_aggrprobe(p)) {
2077                         list_for_each_entry_rcu(kp, &p->list, list)
2078                                 report_probe(pi, kp, sym, offset, modname, p);
2079                 } else
2080                         report_probe(pi, p, sym, offset, modname, NULL);
2081         }
2082         preempt_enable();
2083         return 0;
2084 }
2085 
2086 static const struct seq_operations kprobes_seq_ops = {
2087         .start = kprobe_seq_start,
2088         .next  = kprobe_seq_next,
2089         .stop  = kprobe_seq_stop,
2090         .show  = show_kprobe_addr
2091 };
2092 
2093 static int __kprobes kprobes_open(struct inode *inode, struct file *filp)
2094 {
2095         return seq_open(filp, &kprobes_seq_ops);
2096 }
2097 
2098 static const struct file_operations debugfs_kprobes_operations = {
2099         .open           = kprobes_open,
2100         .read           = seq_read,
2101         .llseek         = seq_lseek,
2102         .release        = seq_release,
2103 };
2104 
2105 static void __kprobes arm_all_kprobes(void)
2106 {
2107         struct hlist_head *head;
2108         struct hlist_node *node;
2109         struct kprobe *p;
2110         unsigned int i;
2111 
2112         mutex_lock(&kprobe_mutex);
2113 
2114         /* If kprobes are armed, just return */
2115         if (!kprobes_all_disarmed)
2116                 goto already_enabled;
2117 
2118         /* Arming kprobes doesn't optimize kprobe itself */
2119         mutex_lock(&text_mutex);
2120         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2121                 head = &kprobe_table[i];
2122                 hlist_for_each_entry_rcu(p, node, head, hlist)
2123                         if (!kprobe_disabled(p))
2124                                 __arm_kprobe(p);
2125         }
2126         mutex_unlock(&text_mutex);
2127 
2128         kprobes_all_disarmed = false;
2129         printk(KERN_INFO "Kprobes globally enabled\n");
2130 
2131 already_enabled:
2132         mutex_unlock(&kprobe_mutex);
2133         return;
2134 }
2135 
2136 static void __kprobes disarm_all_kprobes(void)
2137 {
2138         struct hlist_head *head;
2139         struct hlist_node *node;
2140         struct kprobe *p;
2141         unsigned int i;
2142 
2143         mutex_lock(&kprobe_mutex);
2144 
2145         /* If kprobes are already disarmed, just return */
2146         if (kprobes_all_disarmed) {
2147                 mutex_unlock(&kprobe_mutex);
2148                 return;
2149         }
2150 
2151         kprobes_all_disarmed = true;
2152         printk(KERN_INFO "Kprobes globally disabled\n");
2153 
2154         mutex_lock(&text_mutex);
2155         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2156                 head = &kprobe_table[i];
2157                 hlist_for_each_entry_rcu(p, node, head, hlist) {
2158                         if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
2159                                 __disarm_kprobe(p, false);
2160                 }
2161         }
2162         mutex_unlock(&text_mutex);
2163         mutex_unlock(&kprobe_mutex);
2164 
2165         /* Wait for disarming all kprobes by optimizer */
2166         wait_for_kprobe_optimizer();
2167 }
2168 
2169 /*
2170  * XXX: The debugfs bool file interface doesn't allow for callbacks
2171  * when the bool state is switched. We can reuse that facility when
2172  * available
2173  */
2174 static ssize_t read_enabled_file_bool(struct file *file,
2175                char __user *user_buf, size_t count, loff_t *ppos)
2176 {
2177         char buf[3];
2178 
2179         if (!kprobes_all_disarmed)
2180                 buf[0] = '1';
2181         else
2182                 buf[0] = '';
2183         buf[1] = '\n';
2184         buf[2] = 0x00;
2185         return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
2186 }
2187 
2188 static ssize_t write_enabled_file_bool(struct file *file,
2189                const char __user *user_buf, size_t count, loff_t *ppos)
2190 {
2191         char buf[32];
2192         int buf_size;
2193 
2194         buf_size = min(count, (sizeof(buf)-1));
2195         if (copy_from_user(buf, user_buf, buf_size))
2196                 return -EFAULT;
2197 
2198         switch (buf[0]) {
2199         case 'y':
2200         case 'Y':
2201         case '1':
2202                 arm_all_kprobes();
2203                 break;
2204         case 'n':
2205         case 'N':
2206         case '':
2207                 disarm_all_kprobes();
2208                 break;
2209         }
2210 
2211         return count;
2212 }
2213 
2214 static const struct file_operations fops_kp = {
2215         .read =         read_enabled_file_bool,
2216         .write =        write_enabled_file_bool,
2217         .llseek =       default_llseek,
2218 };
2219 
2220 static int __kprobes debugfs_kprobe_init(void)
2221 {
2222         struct dentry *dir, *file;
2223         unsigned int value = 1;
2224 
2225         dir = debugfs_create_dir("kprobes", NULL);
2226         if (!dir)
2227                 return -ENOMEM;
2228 
2229         file = debugfs_create_file("list", 0444, dir, NULL,
2230                                 &debugfs_kprobes_operations);
2231         if (!file) {
2232                 debugfs_remove(dir);
2233                 return -ENOMEM;
2234         }
2235 
2236         file = debugfs_create_file("enabled", 0600, dir,
2237                                         &value, &fops_kp);
2238         if (!file) {
2239                 debugfs_remove(dir);
2240                 return -ENOMEM;
2241         }
2242 
2243         return 0;
2244 }
2245 
2246 late_initcall(debugfs_kprobe_init);
2247 #endif /* CONFIG_DEBUG_FS */
2248 
2249 module_init(init_kprobes);
2250 
2251 /* defined in arch/.../kernel/kprobes.c */
2252 EXPORT_SYMBOL_GPL(jprobe_return);
2253 

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