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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/export.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         raw_spinlock_t lock ____cacheline_aligned_in_smp;
 82 } kretprobe_table_locks[KPROBE_TABLE_SIZE];
 83 
 84 static raw_spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
 85 {
 86         return &(kretprobe_table_locks[hash].lock);
 87 }
 88 
 89 /* Blacklist -- list of struct kprobe_blacklist_entry */
 90 static LIST_HEAD(kprobe_blacklist);
 91 
 92 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
 93 /*
 94  * kprobe->ainsn.insn points to the copy of the instruction to be
 95  * single-stepped. x86_64, POWER4 and above have no-exec support and
 96  * stepping on the instruction on a vmalloced/kmalloced/data page
 97  * is a recipe for disaster
 98  */
 99 struct kprobe_insn_page {
100         struct list_head list;
101         kprobe_opcode_t *insns;         /* Page of instruction slots */
102         struct kprobe_insn_cache *cache;
103         int nused;
104         int ngarbage;
105         char slot_used[];
106 };
107 
108 #define KPROBE_INSN_PAGE_SIZE(slots)                    \
109         (offsetof(struct kprobe_insn_page, slot_used) + \
110          (sizeof(char) * (slots)))
111 
112 static int slots_per_page(struct kprobe_insn_cache *c)
113 {
114         return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));
115 }
116 
117 enum kprobe_slot_state {
118         SLOT_CLEAN = 0,
119         SLOT_DIRTY = 1,
120         SLOT_USED = 2,
121 };
122 
123 static void *alloc_insn_page(void)
124 {
125         return module_alloc(PAGE_SIZE);
126 }
127 
128 static void free_insn_page(void *page)
129 {
130         module_free(NULL, page);
131 }
132 
133 struct kprobe_insn_cache kprobe_insn_slots = {
134         .mutex = __MUTEX_INITIALIZER(kprobe_insn_slots.mutex),
135         .alloc = alloc_insn_page,
136         .free = free_insn_page,
137         .pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
138         .insn_size = MAX_INSN_SIZE,
139         .nr_garbage = 0,
140 };
141 static int collect_garbage_slots(struct kprobe_insn_cache *c);
142 
143 /**
144  * __get_insn_slot() - Find a slot on an executable page for an instruction.
145  * We allocate an executable page if there's no room on existing ones.
146  */
147 kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c)
148 {
149         struct kprobe_insn_page *kip;
150         kprobe_opcode_t *slot = NULL;
151 
152         mutex_lock(&c->mutex);
153  retry:
154         list_for_each_entry(kip, &c->pages, list) {
155                 if (kip->nused < slots_per_page(c)) {
156                         int i;
157                         for (i = 0; i < slots_per_page(c); i++) {
158                                 if (kip->slot_used[i] == SLOT_CLEAN) {
159                                         kip->slot_used[i] = SLOT_USED;
160                                         kip->nused++;
161                                         slot = kip->insns + (i * c->insn_size);
162                                         goto out;
163                                 }
164                         }
165                         /* kip->nused is broken. Fix it. */
166                         kip->nused = slots_per_page(c);
167                         WARN_ON(1);
168                 }
169         }
170 
171         /* If there are any garbage slots, collect it and try again. */
172         if (c->nr_garbage && collect_garbage_slots(c) == 0)
173                 goto retry;
174 
175         /* All out of space.  Need to allocate a new page. */
176         kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
177         if (!kip)
178                 goto out;
179 
180         /*
181          * Use module_alloc so this page is within +/- 2GB of where the
182          * kernel image and loaded module images reside. This is required
183          * so x86_64 can correctly handle the %rip-relative fixups.
184          */
185         kip->insns = c->alloc();
186         if (!kip->insns) {
187                 kfree(kip);
188                 goto out;
189         }
190         INIT_LIST_HEAD(&kip->list);
191         memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c));
192         kip->slot_used[0] = SLOT_USED;
193         kip->nused = 1;
194         kip->ngarbage = 0;
195         kip->cache = c;
196         list_add(&kip->list, &c->pages);
197         slot = kip->insns;
198 out:
199         mutex_unlock(&c->mutex);
200         return slot;
201 }
202 
203 /* Return 1 if all garbages are collected, otherwise 0. */
204 static int collect_one_slot(struct kprobe_insn_page *kip, int idx)
205 {
206         kip->slot_used[idx] = SLOT_CLEAN;
207         kip->nused--;
208         if (kip->nused == 0) {
209                 /*
210                  * Page is no longer in use.  Free it unless
211                  * it's the last one.  We keep the last one
212                  * so as not to have to set it up again the
213                  * next time somebody inserts a probe.
214                  */
215                 if (!list_is_singular(&kip->list)) {
216                         list_del(&kip->list);
217                         kip->cache->free(kip->insns);
218                         kfree(kip);
219                 }
220                 return 1;
221         }
222         return 0;
223 }
224 
225 static int collect_garbage_slots(struct kprobe_insn_cache *c)
226 {
227         struct kprobe_insn_page *kip, *next;
228 
229         /* Ensure no-one is interrupted on the garbages */
230         synchronize_sched();
231 
232         list_for_each_entry_safe(kip, next, &c->pages, list) {
233                 int i;
234                 if (kip->ngarbage == 0)
235                         continue;
236                 kip->ngarbage = 0;      /* we will collect all garbages */
237                 for (i = 0; i < slots_per_page(c); i++) {
238                         if (kip->slot_used[i] == SLOT_DIRTY &&
239                             collect_one_slot(kip, i))
240                                 break;
241                 }
242         }
243         c->nr_garbage = 0;
244         return 0;
245 }
246 
247 void __free_insn_slot(struct kprobe_insn_cache *c,
248                       kprobe_opcode_t *slot, int dirty)
249 {
250         struct kprobe_insn_page *kip;
251 
252         mutex_lock(&c->mutex);
253         list_for_each_entry(kip, &c->pages, list) {
254                 long idx = ((long)slot - (long)kip->insns) /
255                                 (c->insn_size * sizeof(kprobe_opcode_t));
256                 if (idx >= 0 && idx < slots_per_page(c)) {
257                         WARN_ON(kip->slot_used[idx] != SLOT_USED);
258                         if (dirty) {
259                                 kip->slot_used[idx] = SLOT_DIRTY;
260                                 kip->ngarbage++;
261                                 if (++c->nr_garbage > slots_per_page(c))
262                                         collect_garbage_slots(c);
263                         } else
264                                 collect_one_slot(kip, idx);
265                         goto out;
266                 }
267         }
268         /* Could not free this slot. */
269         WARN_ON(1);
270 out:
271         mutex_unlock(&c->mutex);
272 }
273 
274 #ifdef CONFIG_OPTPROBES
275 /* For optimized_kprobe buffer */
276 struct kprobe_insn_cache kprobe_optinsn_slots = {
277         .mutex = __MUTEX_INITIALIZER(kprobe_optinsn_slots.mutex),
278         .alloc = alloc_insn_page,
279         .free = free_insn_page,
280         .pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
281         /* .insn_size is initialized later */
282         .nr_garbage = 0,
283 };
284 #endif
285 #endif
286 
287 /* We have preemption disabled.. so it is safe to use __ versions */
288 static inline void set_kprobe_instance(struct kprobe *kp)
289 {
290         __this_cpu_write(kprobe_instance, kp);
291 }
292 
293 static inline void reset_kprobe_instance(void)
294 {
295         __this_cpu_write(kprobe_instance, NULL);
296 }
297 
298 /*
299  * This routine is called either:
300  *      - under the kprobe_mutex - during kprobe_[un]register()
301  *                              OR
302  *      - with preemption disabled - from arch/xxx/kernel/kprobes.c
303  */
304 struct kprobe *get_kprobe(void *addr)
305 {
306         struct hlist_head *head;
307         struct kprobe *p;
308 
309         head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
310         hlist_for_each_entry_rcu(p, head, hlist) {
311                 if (p->addr == addr)
312                         return p;
313         }
314 
315         return NULL;
316 }
317 NOKPROBE_SYMBOL(get_kprobe);
318 
319 static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs);
320 
321 /* Return true if the kprobe is an aggregator */
322 static inline int kprobe_aggrprobe(struct kprobe *p)
323 {
324         return p->pre_handler == aggr_pre_handler;
325 }
326 
327 /* Return true(!0) if the kprobe is unused */
328 static inline int kprobe_unused(struct kprobe *p)
329 {
330         return kprobe_aggrprobe(p) && kprobe_disabled(p) &&
331                list_empty(&p->list);
332 }
333 
334 /*
335  * Keep all fields in the kprobe consistent
336  */
337 static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p)
338 {
339         memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t));
340         memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn));
341 }
342 
343 #ifdef CONFIG_OPTPROBES
344 /* NOTE: change this value only with kprobe_mutex held */
345 static bool kprobes_allow_optimization;
346 
347 /*
348  * Call all pre_handler on the list, but ignores its return value.
349  * This must be called from arch-dep optimized caller.
350  */
351 void opt_pre_handler(struct kprobe *p, struct pt_regs *regs)
352 {
353         struct kprobe *kp;
354 
355         list_for_each_entry_rcu(kp, &p->list, list) {
356                 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
357                         set_kprobe_instance(kp);
358                         kp->pre_handler(kp, regs);
359                 }
360                 reset_kprobe_instance();
361         }
362 }
363 NOKPROBE_SYMBOL(opt_pre_handler);
364 
365 /* Free optimized instructions and optimized_kprobe */
366 static void free_aggr_kprobe(struct kprobe *p)
367 {
368         struct optimized_kprobe *op;
369 
370         op = container_of(p, struct optimized_kprobe, kp);
371         arch_remove_optimized_kprobe(op);
372         arch_remove_kprobe(p);
373         kfree(op);
374 }
375 
376 /* Return true(!0) if the kprobe is ready for optimization. */
377 static inline int kprobe_optready(struct kprobe *p)
378 {
379         struct optimized_kprobe *op;
380 
381         if (kprobe_aggrprobe(p)) {
382                 op = container_of(p, struct optimized_kprobe, kp);
383                 return arch_prepared_optinsn(&op->optinsn);
384         }
385 
386         return 0;
387 }
388 
389 /* Return true(!0) if the kprobe is disarmed. Note: p must be on hash list */
390 static inline int kprobe_disarmed(struct kprobe *p)
391 {
392         struct optimized_kprobe *op;
393 
394         /* If kprobe is not aggr/opt probe, just return kprobe is disabled */
395         if (!kprobe_aggrprobe(p))
396                 return kprobe_disabled(p);
397 
398         op = container_of(p, struct optimized_kprobe, kp);
399 
400         return kprobe_disabled(p) && list_empty(&op->list);
401 }
402 
403 /* Return true(!0) if the probe is queued on (un)optimizing lists */
404 static int kprobe_queued(struct kprobe *p)
405 {
406         struct optimized_kprobe *op;
407 
408         if (kprobe_aggrprobe(p)) {
409                 op = container_of(p, struct optimized_kprobe, kp);
410                 if (!list_empty(&op->list))
411                         return 1;
412         }
413         return 0;
414 }
415 
416 /*
417  * Return an optimized kprobe whose optimizing code replaces
418  * instructions including addr (exclude breakpoint).
419  */
420 static struct kprobe *get_optimized_kprobe(unsigned long addr)
421 {
422         int i;
423         struct kprobe *p = NULL;
424         struct optimized_kprobe *op;
425 
426         /* Don't check i == 0, since that is a breakpoint case. */
427         for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH; i++)
428                 p = get_kprobe((void *)(addr - i));
429 
430         if (p && kprobe_optready(p)) {
431                 op = container_of(p, struct optimized_kprobe, kp);
432                 if (arch_within_optimized_kprobe(op, addr))
433                         return p;
434         }
435 
436         return NULL;
437 }
438 
439 /* Optimization staging list, protected by kprobe_mutex */
440 static LIST_HEAD(optimizing_list);
441 static LIST_HEAD(unoptimizing_list);
442 static LIST_HEAD(freeing_list);
443 
444 static void kprobe_optimizer(struct work_struct *work);
445 static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
446 #define OPTIMIZE_DELAY 5
447 
448 /*
449  * Optimize (replace a breakpoint with a jump) kprobes listed on
450  * optimizing_list.
451  */
452 static void do_optimize_kprobes(void)
453 {
454         /* Optimization never be done when disarmed */
455         if (kprobes_all_disarmed || !kprobes_allow_optimization ||
456             list_empty(&optimizing_list))
457                 return;
458 
459         /*
460          * The optimization/unoptimization refers online_cpus via
461          * stop_machine() and cpu-hotplug modifies online_cpus.
462          * And same time, text_mutex will be held in cpu-hotplug and here.
463          * This combination can cause a deadlock (cpu-hotplug try to lock
464          * text_mutex but stop_machine can not be done because online_cpus
465          * has been changed)
466          * To avoid this deadlock, we need to call get_online_cpus()
467          * for preventing cpu-hotplug outside of text_mutex locking.
468          */
469         get_online_cpus();
470         mutex_lock(&text_mutex);
471         arch_optimize_kprobes(&optimizing_list);
472         mutex_unlock(&text_mutex);
473         put_online_cpus();
474 }
475 
476 /*
477  * Unoptimize (replace a jump with a breakpoint and remove the breakpoint
478  * if need) kprobes listed on unoptimizing_list.
479  */
480 static void do_unoptimize_kprobes(void)
481 {
482         struct optimized_kprobe *op, *tmp;
483 
484         /* Unoptimization must be done anytime */
485         if (list_empty(&unoptimizing_list))
486                 return;
487 
488         /* Ditto to do_optimize_kprobes */
489         get_online_cpus();
490         mutex_lock(&text_mutex);
491         arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list);
492         /* Loop free_list for disarming */
493         list_for_each_entry_safe(op, tmp, &freeing_list, list) {
494                 /* Disarm probes if marked disabled */
495                 if (kprobe_disabled(&op->kp))
496                         arch_disarm_kprobe(&op->kp);
497                 if (kprobe_unused(&op->kp)) {
498                         /*
499                          * Remove unused probes from hash list. After waiting
500                          * for synchronization, these probes are reclaimed.
501                          * (reclaiming is done by do_free_cleaned_kprobes.)
502                          */
503                         hlist_del_rcu(&op->kp.hlist);
504                 } else
505                         list_del_init(&op->list);
506         }
507         mutex_unlock(&text_mutex);
508         put_online_cpus();
509 }
510 
511 /* Reclaim all kprobes on the free_list */
512 static void do_free_cleaned_kprobes(void)
513 {
514         struct optimized_kprobe *op, *tmp;
515 
516         list_for_each_entry_safe(op, tmp, &freeing_list, list) {
517                 BUG_ON(!kprobe_unused(&op->kp));
518                 list_del_init(&op->list);
519                 free_aggr_kprobe(&op->kp);
520         }
521 }
522 
523 /* Start optimizer after OPTIMIZE_DELAY passed */
524 static void kick_kprobe_optimizer(void)
525 {
526         schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
527 }
528 
529 /* Kprobe jump optimizer */
530 static void kprobe_optimizer(struct work_struct *work)
531 {
532         mutex_lock(&kprobe_mutex);
533         /* Lock modules while optimizing kprobes */
534         mutex_lock(&module_mutex);
535 
536         /*
537          * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
538          * kprobes before waiting for quiesence period.
539          */
540         do_unoptimize_kprobes();
541 
542         /*
543          * Step 2: Wait for quiesence period to ensure all running interrupts
544          * are done. Because optprobe may modify multiple instructions
545          * there is a chance that Nth instruction is interrupted. In that
546          * case, running interrupt can return to 2nd-Nth byte of jump
547          * instruction. This wait is for avoiding it.
548          */
549         synchronize_sched();
550 
551         /* Step 3: Optimize kprobes after quiesence period */
552         do_optimize_kprobes();
553 
554         /* Step 4: Free cleaned kprobes after quiesence period */
555         do_free_cleaned_kprobes();
556 
557         mutex_unlock(&module_mutex);
558         mutex_unlock(&kprobe_mutex);
559 
560         /* Step 5: Kick optimizer again if needed */
561         if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
562                 kick_kprobe_optimizer();
563 }
564 
565 /* Wait for completing optimization and unoptimization */
566 static void wait_for_kprobe_optimizer(void)
567 {
568         mutex_lock(&kprobe_mutex);
569 
570         while (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) {
571                 mutex_unlock(&kprobe_mutex);
572 
573                 /* this will also make optimizing_work execute immmediately */
574                 flush_delayed_work(&optimizing_work);
575                 /* @optimizing_work might not have been queued yet, relax */
576                 cpu_relax();
577 
578                 mutex_lock(&kprobe_mutex);
579         }
580 
581         mutex_unlock(&kprobe_mutex);
582 }
583 
584 /* Optimize kprobe if p is ready to be optimized */
585 static void optimize_kprobe(struct kprobe *p)
586 {
587         struct optimized_kprobe *op;
588 
589         /* Check if the kprobe is disabled or not ready for optimization. */
590         if (!kprobe_optready(p) || !kprobes_allow_optimization ||
591             (kprobe_disabled(p) || kprobes_all_disarmed))
592                 return;
593 
594         /* Both of break_handler and post_handler are not supported. */
595         if (p->break_handler || p->post_handler)
596                 return;
597 
598         op = container_of(p, struct optimized_kprobe, kp);
599 
600         /* Check there is no other kprobes at the optimized instructions */
601         if (arch_check_optimized_kprobe(op) < 0)
602                 return;
603 
604         /* Check if it is already optimized. */
605         if (op->kp.flags & KPROBE_FLAG_OPTIMIZED)
606                 return;
607         op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
608 
609         if (!list_empty(&op->list))
610                 /* This is under unoptimizing. Just dequeue the probe */
611                 list_del_init(&op->list);
612         else {
613                 list_add(&op->list, &optimizing_list);
614                 kick_kprobe_optimizer();
615         }
616 }
617 
618 /* Short cut to direct unoptimizing */
619 static void force_unoptimize_kprobe(struct optimized_kprobe *op)
620 {
621         get_online_cpus();
622         arch_unoptimize_kprobe(op);
623         put_online_cpus();
624         if (kprobe_disabled(&op->kp))
625                 arch_disarm_kprobe(&op->kp);
626 }
627 
628 /* Unoptimize a kprobe if p is optimized */
629 static void unoptimize_kprobe(struct kprobe *p, bool force)
630 {
631         struct optimized_kprobe *op;
632 
633         if (!kprobe_aggrprobe(p) || kprobe_disarmed(p))
634                 return; /* This is not an optprobe nor optimized */
635 
636         op = container_of(p, struct optimized_kprobe, kp);
637         if (!kprobe_optimized(p)) {
638                 /* Unoptimized or unoptimizing case */
639                 if (force && !list_empty(&op->list)) {
640                         /*
641                          * Only if this is unoptimizing kprobe and forced,
642                          * forcibly unoptimize it. (No need to unoptimize
643                          * unoptimized kprobe again :)
644                          */
645                         list_del_init(&op->list);
646                         force_unoptimize_kprobe(op);
647                 }
648                 return;
649         }
650 
651         op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
652         if (!list_empty(&op->list)) {
653                 /* Dequeue from the optimization queue */
654                 list_del_init(&op->list);
655                 return;
656         }
657         /* Optimized kprobe case */
658         if (force)
659                 /* Forcibly update the code: this is a special case */
660                 force_unoptimize_kprobe(op);
661         else {
662                 list_add(&op->list, &unoptimizing_list);
663                 kick_kprobe_optimizer();
664         }
665 }
666 
667 /* Cancel unoptimizing for reusing */
668 static void reuse_unused_kprobe(struct kprobe *ap)
669 {
670         struct optimized_kprobe *op;
671 
672         BUG_ON(!kprobe_unused(ap));
673         /*
674          * Unused kprobe MUST be on the way of delayed unoptimizing (means
675          * there is still a relative jump) and disabled.
676          */
677         op = container_of(ap, struct optimized_kprobe, kp);
678         if (unlikely(list_empty(&op->list)))
679                 printk(KERN_WARNING "Warning: found a stray unused "
680                         "aggrprobe@%p\n", ap->addr);
681         /* Enable the probe again */
682         ap->flags &= ~KPROBE_FLAG_DISABLED;
683         /* Optimize it again (remove from op->list) */
684         BUG_ON(!kprobe_optready(ap));
685         optimize_kprobe(ap);
686 }
687 
688 /* Remove optimized instructions */
689 static void kill_optimized_kprobe(struct kprobe *p)
690 {
691         struct optimized_kprobe *op;
692 
693         op = container_of(p, struct optimized_kprobe, kp);
694         if (!list_empty(&op->list))
695                 /* Dequeue from the (un)optimization queue */
696                 list_del_init(&op->list);
697         op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
698 
699         if (kprobe_unused(p)) {
700                 /* Enqueue if it is unused */
701                 list_add(&op->list, &freeing_list);
702                 /*
703                  * Remove unused probes from the hash list. After waiting
704                  * for synchronization, this probe is reclaimed.
705                  * (reclaiming is done by do_free_cleaned_kprobes().)
706                  */
707                 hlist_del_rcu(&op->kp.hlist);
708         }
709 
710         /* Don't touch the code, because it is already freed. */
711         arch_remove_optimized_kprobe(op);
712 }
713 
714 /* Try to prepare optimized instructions */
715 static void prepare_optimized_kprobe(struct kprobe *p)
716 {
717         struct optimized_kprobe *op;
718 
719         op = container_of(p, struct optimized_kprobe, kp);
720         arch_prepare_optimized_kprobe(op);
721 }
722 
723 /* Allocate new optimized_kprobe and try to prepare optimized instructions */
724 static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
725 {
726         struct optimized_kprobe *op;
727 
728         op = kzalloc(sizeof(struct optimized_kprobe), GFP_KERNEL);
729         if (!op)
730                 return NULL;
731 
732         INIT_LIST_HEAD(&op->list);
733         op->kp.addr = p->addr;
734         arch_prepare_optimized_kprobe(op);
735 
736         return &op->kp;
737 }
738 
739 static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p);
740 
741 /*
742  * Prepare an optimized_kprobe and optimize it
743  * NOTE: p must be a normal registered kprobe
744  */
745 static void try_to_optimize_kprobe(struct kprobe *p)
746 {
747         struct kprobe *ap;
748         struct optimized_kprobe *op;
749 
750         /* Impossible to optimize ftrace-based kprobe */
751         if (kprobe_ftrace(p))
752                 return;
753 
754         /* For preparing optimization, jump_label_text_reserved() is called */
755         jump_label_lock();
756         mutex_lock(&text_mutex);
757 
758         ap = alloc_aggr_kprobe(p);
759         if (!ap)
760                 goto out;
761 
762         op = container_of(ap, struct optimized_kprobe, kp);
763         if (!arch_prepared_optinsn(&op->optinsn)) {
764                 /* If failed to setup optimizing, fallback to kprobe */
765                 arch_remove_optimized_kprobe(op);
766                 kfree(op);
767                 goto out;
768         }
769 
770         init_aggr_kprobe(ap, p);
771         optimize_kprobe(ap);    /* This just kicks optimizer thread */
772 
773 out:
774         mutex_unlock(&text_mutex);
775         jump_label_unlock();
776 }
777 
778 #ifdef CONFIG_SYSCTL
779 static void optimize_all_kprobes(void)
780 {
781         struct hlist_head *head;
782         struct kprobe *p;
783         unsigned int i;
784 
785         mutex_lock(&kprobe_mutex);
786         /* If optimization is already allowed, just return */
787         if (kprobes_allow_optimization)
788                 goto out;
789 
790         kprobes_allow_optimization = true;
791         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
792                 head = &kprobe_table[i];
793                 hlist_for_each_entry_rcu(p, head, hlist)
794                         if (!kprobe_disabled(p))
795                                 optimize_kprobe(p);
796         }
797         printk(KERN_INFO "Kprobes globally optimized\n");
798 out:
799         mutex_unlock(&kprobe_mutex);
800 }
801 
802 static void unoptimize_all_kprobes(void)
803 {
804         struct hlist_head *head;
805         struct kprobe *p;
806         unsigned int i;
807 
808         mutex_lock(&kprobe_mutex);
809         /* If optimization is already prohibited, just return */
810         if (!kprobes_allow_optimization) {
811                 mutex_unlock(&kprobe_mutex);
812                 return;
813         }
814 
815         kprobes_allow_optimization = false;
816         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
817                 head = &kprobe_table[i];
818                 hlist_for_each_entry_rcu(p, head, hlist) {
819                         if (!kprobe_disabled(p))
820                                 unoptimize_kprobe(p, false);
821                 }
822         }
823         mutex_unlock(&kprobe_mutex);
824 
825         /* Wait for unoptimizing completion */
826         wait_for_kprobe_optimizer();
827         printk(KERN_INFO "Kprobes globally unoptimized\n");
828 }
829 
830 static DEFINE_MUTEX(kprobe_sysctl_mutex);
831 int sysctl_kprobes_optimization;
832 int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
833                                       void __user *buffer, size_t *length,
834                                       loff_t *ppos)
835 {
836         int ret;
837 
838         mutex_lock(&kprobe_sysctl_mutex);
839         sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0;
840         ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
841 
842         if (sysctl_kprobes_optimization)
843                 optimize_all_kprobes();
844         else
845                 unoptimize_all_kprobes();
846         mutex_unlock(&kprobe_sysctl_mutex);
847 
848         return ret;
849 }
850 #endif /* CONFIG_SYSCTL */
851 
852 /* Put a breakpoint for a probe. Must be called with text_mutex locked */
853 static void __arm_kprobe(struct kprobe *p)
854 {
855         struct kprobe *_p;
856 
857         /* Check collision with other optimized kprobes */
858         _p = get_optimized_kprobe((unsigned long)p->addr);
859         if (unlikely(_p))
860                 /* Fallback to unoptimized kprobe */
861                 unoptimize_kprobe(_p, true);
862 
863         arch_arm_kprobe(p);
864         optimize_kprobe(p);     /* Try to optimize (add kprobe to a list) */
865 }
866 
867 /* Remove the breakpoint of a probe. Must be called with text_mutex locked */
868 static void __disarm_kprobe(struct kprobe *p, bool reopt)
869 {
870         struct kprobe *_p;
871 
872         unoptimize_kprobe(p, false);    /* Try to unoptimize */
873 
874         if (!kprobe_queued(p)) {
875                 arch_disarm_kprobe(p);
876                 /* If another kprobe was blocked, optimize it. */
877                 _p = get_optimized_kprobe((unsigned long)p->addr);
878                 if (unlikely(_p) && reopt)
879                         optimize_kprobe(_p);
880         }
881         /* TODO: reoptimize others after unoptimized this probe */
882 }
883 
884 #else /* !CONFIG_OPTPROBES */
885 
886 #define optimize_kprobe(p)                      do {} while (0)
887 #define unoptimize_kprobe(p, f)                 do {} while (0)
888 #define kill_optimized_kprobe(p)                do {} while (0)
889 #define prepare_optimized_kprobe(p)             do {} while (0)
890 #define try_to_optimize_kprobe(p)               do {} while (0)
891 #define __arm_kprobe(p)                         arch_arm_kprobe(p)
892 #define __disarm_kprobe(p, o)                   arch_disarm_kprobe(p)
893 #define kprobe_disarmed(p)                      kprobe_disabled(p)
894 #define wait_for_kprobe_optimizer()             do {} while (0)
895 
896 /* There should be no unused kprobes can be reused without optimization */
897 static void reuse_unused_kprobe(struct kprobe *ap)
898 {
899         printk(KERN_ERR "Error: There should be no unused kprobe here.\n");
900         BUG_ON(kprobe_unused(ap));
901 }
902 
903 static void free_aggr_kprobe(struct kprobe *p)
904 {
905         arch_remove_kprobe(p);
906         kfree(p);
907 }
908 
909 static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
910 {
911         return kzalloc(sizeof(struct kprobe), GFP_KERNEL);
912 }
913 #endif /* CONFIG_OPTPROBES */
914 
915 #ifdef CONFIG_KPROBES_ON_FTRACE
916 static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
917         .func = kprobe_ftrace_handler,
918         .flags = FTRACE_OPS_FL_SAVE_REGS,
919 };
920 static int kprobe_ftrace_enabled;
921 
922 /* Must ensure p->addr is really on ftrace */
923 static int prepare_kprobe(struct kprobe *p)
924 {
925         if (!kprobe_ftrace(p))
926                 return arch_prepare_kprobe(p);
927 
928         return arch_prepare_kprobe_ftrace(p);
929 }
930 
931 /* Caller must lock kprobe_mutex */
932 static void arm_kprobe_ftrace(struct kprobe *p)
933 {
934         int ret;
935 
936         ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
937                                    (unsigned long)p->addr, 0, 0);
938         WARN(ret < 0, "Failed to arm kprobe-ftrace at %p (%d)\n", p->addr, ret);
939         kprobe_ftrace_enabled++;
940         if (kprobe_ftrace_enabled == 1) {
941                 ret = register_ftrace_function(&kprobe_ftrace_ops);
942                 WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
943         }
944 }
945 
946 /* Caller must lock kprobe_mutex */
947 static void disarm_kprobe_ftrace(struct kprobe *p)
948 {
949         int ret;
950 
951         kprobe_ftrace_enabled--;
952         if (kprobe_ftrace_enabled == 0) {
953                 ret = unregister_ftrace_function(&kprobe_ftrace_ops);
954                 WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
955         }
956         ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
957                            (unsigned long)p->addr, 1, 0);
958         WARN(ret < 0, "Failed to disarm kprobe-ftrace at %p (%d)\n", p->addr, ret);
959 }
960 #else   /* !CONFIG_KPROBES_ON_FTRACE */
961 #define prepare_kprobe(p)       arch_prepare_kprobe(p)
962 #define arm_kprobe_ftrace(p)    do {} while (0)
963 #define disarm_kprobe_ftrace(p) do {} while (0)
964 #endif
965 
966 /* Arm a kprobe with text_mutex */
967 static void arm_kprobe(struct kprobe *kp)
968 {
969         if (unlikely(kprobe_ftrace(kp))) {
970                 arm_kprobe_ftrace(kp);
971                 return;
972         }
973         /*
974          * Here, since __arm_kprobe() doesn't use stop_machine(),
975          * this doesn't cause deadlock on text_mutex. So, we don't
976          * need get_online_cpus().
977          */
978         mutex_lock(&text_mutex);
979         __arm_kprobe(kp);
980         mutex_unlock(&text_mutex);
981 }
982 
983 /* Disarm a kprobe with text_mutex */
984 static void disarm_kprobe(struct kprobe *kp, bool reopt)
985 {
986         if (unlikely(kprobe_ftrace(kp))) {
987                 disarm_kprobe_ftrace(kp);
988                 return;
989         }
990         /* Ditto */
991         mutex_lock(&text_mutex);
992         __disarm_kprobe(kp, reopt);
993         mutex_unlock(&text_mutex);
994 }
995 
996 /*
997  * Aggregate handlers for multiple kprobes support - these handlers
998  * take care of invoking the individual kprobe handlers on p->list
999  */
1000 static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
1001 {
1002         struct kprobe *kp;
1003 
1004         list_for_each_entry_rcu(kp, &p->list, list) {
1005                 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
1006                         set_kprobe_instance(kp);
1007                         if (kp->pre_handler(kp, regs))
1008                                 return 1;
1009                 }
1010                 reset_kprobe_instance();
1011         }
1012         return 0;
1013 }
1014 NOKPROBE_SYMBOL(aggr_pre_handler);
1015 
1016 static void aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
1017                               unsigned long flags)
1018 {
1019         struct kprobe *kp;
1020 
1021         list_for_each_entry_rcu(kp, &p->list, list) {
1022                 if (kp->post_handler && likely(!kprobe_disabled(kp))) {
1023                         set_kprobe_instance(kp);
1024                         kp->post_handler(kp, regs, flags);
1025                         reset_kprobe_instance();
1026                 }
1027         }
1028 }
1029 NOKPROBE_SYMBOL(aggr_post_handler);
1030 
1031 static int aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
1032                               int trapnr)
1033 {
1034         struct kprobe *cur = __this_cpu_read(kprobe_instance);
1035 
1036         /*
1037          * if we faulted "during" the execution of a user specified
1038          * probe handler, invoke just that probe's fault handler
1039          */
1040         if (cur && cur->fault_handler) {
1041                 if (cur->fault_handler(cur, regs, trapnr))
1042                         return 1;
1043         }
1044         return 0;
1045 }
1046 NOKPROBE_SYMBOL(aggr_fault_handler);
1047 
1048 static int aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
1049 {
1050         struct kprobe *cur = __this_cpu_read(kprobe_instance);
1051         int ret = 0;
1052 
1053         if (cur && cur->break_handler) {
1054                 if (cur->break_handler(cur, regs))
1055                         ret = 1;
1056         }
1057         reset_kprobe_instance();
1058         return ret;
1059 }
1060 NOKPROBE_SYMBOL(aggr_break_handler);
1061 
1062 /* Walks the list and increments nmissed count for multiprobe case */
1063 void kprobes_inc_nmissed_count(struct kprobe *p)
1064 {
1065         struct kprobe *kp;
1066         if (!kprobe_aggrprobe(p)) {
1067                 p->nmissed++;
1068         } else {
1069                 list_for_each_entry_rcu(kp, &p->list, list)
1070                         kp->nmissed++;
1071         }
1072         return;
1073 }
1074 NOKPROBE_SYMBOL(kprobes_inc_nmissed_count);
1075 
1076 void recycle_rp_inst(struct kretprobe_instance *ri,
1077                      struct hlist_head *head)
1078 {
1079         struct kretprobe *rp = ri->rp;
1080 
1081         /* remove rp inst off the rprobe_inst_table */
1082         hlist_del(&ri->hlist);
1083         INIT_HLIST_NODE(&ri->hlist);
1084         if (likely(rp)) {
1085                 raw_spin_lock(&rp->lock);
1086                 hlist_add_head(&ri->hlist, &rp->free_instances);
1087                 raw_spin_unlock(&rp->lock);
1088         } else
1089                 /* Unregistering */
1090                 hlist_add_head(&ri->hlist, head);
1091 }
1092 NOKPROBE_SYMBOL(recycle_rp_inst);
1093 
1094 void kretprobe_hash_lock(struct task_struct *tsk,
1095                          struct hlist_head **head, unsigned long *flags)
1096 __acquires(hlist_lock)
1097 {
1098         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1099         raw_spinlock_t *hlist_lock;
1100 
1101         *head = &kretprobe_inst_table[hash];
1102         hlist_lock = kretprobe_table_lock_ptr(hash);
1103         raw_spin_lock_irqsave(hlist_lock, *flags);
1104 }
1105 NOKPROBE_SYMBOL(kretprobe_hash_lock);
1106 
1107 static void kretprobe_table_lock(unsigned long hash,
1108                                  unsigned long *flags)
1109 __acquires(hlist_lock)
1110 {
1111         raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1112         raw_spin_lock_irqsave(hlist_lock, *flags);
1113 }
1114 NOKPROBE_SYMBOL(kretprobe_table_lock);
1115 
1116 void kretprobe_hash_unlock(struct task_struct *tsk,
1117                            unsigned long *flags)
1118 __releases(hlist_lock)
1119 {
1120         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1121         raw_spinlock_t *hlist_lock;
1122 
1123         hlist_lock = kretprobe_table_lock_ptr(hash);
1124         raw_spin_unlock_irqrestore(hlist_lock, *flags);
1125 }
1126 NOKPROBE_SYMBOL(kretprobe_hash_unlock);
1127 
1128 static void kretprobe_table_unlock(unsigned long hash,
1129                                    unsigned long *flags)
1130 __releases(hlist_lock)
1131 {
1132         raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1133         raw_spin_unlock_irqrestore(hlist_lock, *flags);
1134 }
1135 NOKPROBE_SYMBOL(kretprobe_table_unlock);
1136 
1137 /*
1138  * This function is called from finish_task_switch when task tk becomes dead,
1139  * so that we can recycle any function-return probe instances associated
1140  * with this task. These left over instances represent probed functions
1141  * that have been called but will never return.
1142  */
1143 void kprobe_flush_task(struct task_struct *tk)
1144 {
1145         struct kretprobe_instance *ri;
1146         struct hlist_head *head, empty_rp;
1147         struct hlist_node *tmp;
1148         unsigned long hash, flags = 0;
1149 
1150         if (unlikely(!kprobes_initialized))
1151                 /* Early boot.  kretprobe_table_locks not yet initialized. */
1152                 return;
1153 
1154         INIT_HLIST_HEAD(&empty_rp);
1155         hash = hash_ptr(tk, KPROBE_HASH_BITS);
1156         head = &kretprobe_inst_table[hash];
1157         kretprobe_table_lock(hash, &flags);
1158         hlist_for_each_entry_safe(ri, tmp, head, hlist) {
1159                 if (ri->task == tk)
1160                         recycle_rp_inst(ri, &empty_rp);
1161         }
1162         kretprobe_table_unlock(hash, &flags);
1163         hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
1164                 hlist_del(&ri->hlist);
1165                 kfree(ri);
1166         }
1167 }
1168 NOKPROBE_SYMBOL(kprobe_flush_task);
1169 
1170 static inline void free_rp_inst(struct kretprobe *rp)
1171 {
1172         struct kretprobe_instance *ri;
1173         struct hlist_node *next;
1174 
1175         hlist_for_each_entry_safe(ri, next, &rp->free_instances, hlist) {
1176                 hlist_del(&ri->hlist);
1177                 kfree(ri);
1178         }
1179 }
1180 
1181 static void cleanup_rp_inst(struct kretprobe *rp)
1182 {
1183         unsigned long flags, hash;
1184         struct kretprobe_instance *ri;
1185         struct hlist_node *next;
1186         struct hlist_head *head;
1187 
1188         /* No race here */
1189         for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
1190                 kretprobe_table_lock(hash, &flags);
1191                 head = &kretprobe_inst_table[hash];
1192                 hlist_for_each_entry_safe(ri, next, head, hlist) {
1193                         if (ri->rp == rp)
1194                                 ri->rp = NULL;
1195                 }
1196                 kretprobe_table_unlock(hash, &flags);
1197         }
1198         free_rp_inst(rp);
1199 }
1200 NOKPROBE_SYMBOL(cleanup_rp_inst);
1201 
1202 /*
1203 * Add the new probe to ap->list. Fail if this is the
1204 * second jprobe at the address - two jprobes can't coexist
1205 */
1206 static int add_new_kprobe(struct kprobe *ap, struct kprobe *p)
1207 {
1208         BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
1209 
1210         if (p->break_handler || p->post_handler)
1211                 unoptimize_kprobe(ap, true);    /* Fall back to normal kprobe */
1212 
1213         if (p->break_handler) {
1214                 if (ap->break_handler)
1215                         return -EEXIST;
1216                 list_add_tail_rcu(&p->list, &ap->list);
1217                 ap->break_handler = aggr_break_handler;
1218         } else
1219                 list_add_rcu(&p->list, &ap->list);
1220         if (p->post_handler && !ap->post_handler)
1221                 ap->post_handler = aggr_post_handler;
1222 
1223         return 0;
1224 }
1225 
1226 /*
1227  * Fill in the required fields of the "manager kprobe". Replace the
1228  * earlier kprobe in the hlist with the manager kprobe
1229  */
1230 static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
1231 {
1232         /* Copy p's insn slot to ap */
1233         copy_kprobe(p, ap);
1234         flush_insn_slot(ap);
1235         ap->addr = p->addr;
1236         ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED;
1237         ap->pre_handler = aggr_pre_handler;
1238         ap->fault_handler = aggr_fault_handler;
1239         /* We don't care the kprobe which has gone. */
1240         if (p->post_handler && !kprobe_gone(p))
1241                 ap->post_handler = aggr_post_handler;
1242         if (p->break_handler && !kprobe_gone(p))
1243                 ap->break_handler = aggr_break_handler;
1244 
1245         INIT_LIST_HEAD(&ap->list);
1246         INIT_HLIST_NODE(&ap->hlist);
1247 
1248         list_add_rcu(&p->list, &ap->list);
1249         hlist_replace_rcu(&p->hlist, &ap->hlist);
1250 }
1251 
1252 /*
1253  * This is the second or subsequent kprobe at the address - handle
1254  * the intricacies
1255  */
1256 static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p)
1257 {
1258         int ret = 0;
1259         struct kprobe *ap = orig_p;
1260 
1261         /* For preparing optimization, jump_label_text_reserved() is called */
1262         jump_label_lock();
1263         /*
1264          * Get online CPUs to avoid text_mutex deadlock.with stop machine,
1265          * which is invoked by unoptimize_kprobe() in add_new_kprobe()
1266          */
1267         get_online_cpus();
1268         mutex_lock(&text_mutex);
1269 
1270         if (!kprobe_aggrprobe(orig_p)) {
1271                 /* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */
1272                 ap = alloc_aggr_kprobe(orig_p);
1273                 if (!ap) {
1274                         ret = -ENOMEM;
1275                         goto out;
1276                 }
1277                 init_aggr_kprobe(ap, orig_p);
1278         } else if (kprobe_unused(ap))
1279                 /* This probe is going to die. Rescue it */
1280                 reuse_unused_kprobe(ap);
1281 
1282         if (kprobe_gone(ap)) {
1283                 /*
1284                  * Attempting to insert new probe at the same location that
1285                  * had a probe in the module vaddr area which already
1286                  * freed. So, the instruction slot has already been
1287                  * released. We need a new slot for the new probe.
1288                  */
1289                 ret = arch_prepare_kprobe(ap);
1290                 if (ret)
1291                         /*
1292                          * Even if fail to allocate new slot, don't need to
1293                          * free aggr_probe. It will be used next time, or
1294                          * freed by unregister_kprobe.
1295                          */
1296                         goto out;
1297 
1298                 /* Prepare optimized instructions if possible. */
1299                 prepare_optimized_kprobe(ap);
1300 
1301                 /*
1302                  * Clear gone flag to prevent allocating new slot again, and
1303                  * set disabled flag because it is not armed yet.
1304                  */
1305                 ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
1306                             | KPROBE_FLAG_DISABLED;
1307         }
1308 
1309         /* Copy ap's insn slot to p */
1310         copy_kprobe(ap, p);
1311         ret = add_new_kprobe(ap, p);
1312 
1313 out:
1314         mutex_unlock(&text_mutex);
1315         put_online_cpus();
1316         jump_label_unlock();
1317 
1318         if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) {
1319                 ap->flags &= ~KPROBE_FLAG_DISABLED;
1320                 if (!kprobes_all_disarmed)
1321                         /* Arm the breakpoint again. */
1322                         arm_kprobe(ap);
1323         }
1324         return ret;
1325 }
1326 
1327 bool __weak arch_within_kprobe_blacklist(unsigned long addr)
1328 {
1329         /* The __kprobes marked functions and entry code must not be probed */
1330         return addr >= (unsigned long)__kprobes_text_start &&
1331                addr < (unsigned long)__kprobes_text_end;
1332 }
1333 
1334 static bool within_kprobe_blacklist(unsigned long addr)
1335 {
1336         struct kprobe_blacklist_entry *ent;
1337 
1338         if (arch_within_kprobe_blacklist(addr))
1339                 return true;
1340         /*
1341          * If there exists a kprobe_blacklist, verify and
1342          * fail any probe registration in the prohibited area
1343          */
1344         list_for_each_entry(ent, &kprobe_blacklist, list) {
1345                 if (addr >= ent->start_addr && addr < ent->end_addr)
1346                         return true;
1347         }
1348 
1349         return false;
1350 }
1351 
1352 /*
1353  * If we have a symbol_name argument, look it up and add the offset field
1354  * to it. This way, we can specify a relative address to a symbol.
1355  * This returns encoded errors if it fails to look up symbol or invalid
1356  * combination of parameters.
1357  */
1358 static kprobe_opcode_t *kprobe_addr(struct kprobe *p)
1359 {
1360         kprobe_opcode_t *addr = p->addr;
1361 
1362         if ((p->symbol_name && p->addr) ||
1363             (!p->symbol_name && !p->addr))
1364                 goto invalid;
1365 
1366         if (p->symbol_name) {
1367                 kprobe_lookup_name(p->symbol_name, addr);
1368                 if (!addr)
1369                         return ERR_PTR(-ENOENT);
1370         }
1371 
1372         addr = (kprobe_opcode_t *)(((char *)addr) + p->offset);
1373         if (addr)
1374                 return addr;
1375 
1376 invalid:
1377         return ERR_PTR(-EINVAL);
1378 }
1379 
1380 /* Check passed kprobe is valid and return kprobe in kprobe_table. */
1381 static struct kprobe *__get_valid_kprobe(struct kprobe *p)
1382 {
1383         struct kprobe *ap, *list_p;
1384 
1385         ap = get_kprobe(p->addr);
1386         if (unlikely(!ap))
1387                 return NULL;
1388 
1389         if (p != ap) {
1390                 list_for_each_entry_rcu(list_p, &ap->list, list)
1391                         if (list_p == p)
1392                         /* kprobe p is a valid probe */
1393                                 goto valid;
1394                 return NULL;
1395         }
1396 valid:
1397         return ap;
1398 }
1399 
1400 /* Return error if the kprobe is being re-registered */
1401 static inline int check_kprobe_rereg(struct kprobe *p)
1402 {
1403         int ret = 0;
1404 
1405         mutex_lock(&kprobe_mutex);
1406         if (__get_valid_kprobe(p))
1407                 ret = -EINVAL;
1408         mutex_unlock(&kprobe_mutex);
1409 
1410         return ret;
1411 }
1412 
1413 static int check_kprobe_address_safe(struct kprobe *p,
1414                                      struct module **probed_mod)
1415 {
1416         int ret = 0;
1417         unsigned long ftrace_addr;
1418 
1419         /*
1420          * If the address is located on a ftrace nop, set the
1421          * breakpoint to the following instruction.
1422          */
1423         ftrace_addr = ftrace_location((unsigned long)p->addr);
1424         if (ftrace_addr) {
1425 #ifdef CONFIG_KPROBES_ON_FTRACE
1426                 /* Given address is not on the instruction boundary */
1427                 if ((unsigned long)p->addr != ftrace_addr)
1428                         return -EILSEQ;
1429                 p->flags |= KPROBE_FLAG_FTRACE;
1430 #else   /* !CONFIG_KPROBES_ON_FTRACE */
1431                 return -EINVAL;
1432 #endif
1433         }
1434 
1435         jump_label_lock();
1436         preempt_disable();
1437 
1438         /* Ensure it is not in reserved area nor out of text */
1439         if (!kernel_text_address((unsigned long) p->addr) ||
1440             within_kprobe_blacklist((unsigned long) p->addr) ||
1441             jump_label_text_reserved(p->addr, p->addr)) {
1442                 ret = -EINVAL;
1443                 goto out;
1444         }
1445 
1446         /* Check if are we probing a module */
1447         *probed_mod = __module_text_address((unsigned long) p->addr);
1448         if (*probed_mod) {
1449                 /*
1450                  * We must hold a refcount of the probed module while updating
1451                  * its code to prohibit unexpected unloading.
1452                  */
1453                 if (unlikely(!try_module_get(*probed_mod))) {
1454                         ret = -ENOENT;
1455                         goto out;
1456                 }
1457 
1458                 /*
1459                  * If the module freed .init.text, we couldn't insert
1460                  * kprobes in there.
1461                  */
1462                 if (within_module_init((unsigned long)p->addr, *probed_mod) &&
1463                     (*probed_mod)->state != MODULE_STATE_COMING) {
1464                         module_put(*probed_mod);
1465                         *probed_mod = NULL;
1466                         ret = -ENOENT;
1467                 }
1468         }
1469 out:
1470         preempt_enable();
1471         jump_label_unlock();
1472 
1473         return ret;
1474 }
1475 
1476 int register_kprobe(struct kprobe *p)
1477 {
1478         int ret;
1479         struct kprobe *old_p;
1480         struct module *probed_mod;
1481         kprobe_opcode_t *addr;
1482 
1483         /* Adjust probe address from symbol */
1484         addr = kprobe_addr(p);
1485         if (IS_ERR(addr))
1486                 return PTR_ERR(addr);
1487         p->addr = addr;
1488 
1489         ret = check_kprobe_rereg(p);
1490         if (ret)
1491                 return ret;
1492 
1493         /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
1494         p->flags &= KPROBE_FLAG_DISABLED;
1495         p->nmissed = 0;
1496         INIT_LIST_HEAD(&p->list);
1497 
1498         ret = check_kprobe_address_safe(p, &probed_mod);
1499         if (ret)
1500                 return ret;
1501 
1502         mutex_lock(&kprobe_mutex);
1503 
1504         old_p = get_kprobe(p->addr);
1505         if (old_p) {
1506                 /* Since this may unoptimize old_p, locking text_mutex. */
1507                 ret = register_aggr_kprobe(old_p, p);
1508                 goto out;
1509         }
1510 
1511         mutex_lock(&text_mutex);        /* Avoiding text modification */
1512         ret = prepare_kprobe(p);
1513         mutex_unlock(&text_mutex);
1514         if (ret)
1515                 goto out;
1516 
1517         INIT_HLIST_NODE(&p->hlist);
1518         hlist_add_head_rcu(&p->hlist,
1519                        &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
1520 
1521         if (!kprobes_all_disarmed && !kprobe_disabled(p))
1522                 arm_kprobe(p);
1523 
1524         /* Try to optimize kprobe */
1525         try_to_optimize_kprobe(p);
1526 
1527 out:
1528         mutex_unlock(&kprobe_mutex);
1529 
1530         if (probed_mod)
1531                 module_put(probed_mod);
1532 
1533         return ret;
1534 }
1535 EXPORT_SYMBOL_GPL(register_kprobe);
1536 
1537 /* Check if all probes on the aggrprobe are disabled */
1538 static int aggr_kprobe_disabled(struct kprobe *ap)
1539 {
1540         struct kprobe *kp;
1541 
1542         list_for_each_entry_rcu(kp, &ap->list, list)
1543                 if (!kprobe_disabled(kp))
1544                         /*
1545                          * There is an active probe on the list.
1546                          * We can't disable this ap.
1547                          */
1548                         return 0;
1549 
1550         return 1;
1551 }
1552 
1553 /* Disable one kprobe: Make sure called under kprobe_mutex is locked */
1554 static struct kprobe *__disable_kprobe(struct kprobe *p)
1555 {
1556         struct kprobe *orig_p;
1557 
1558         /* Get an original kprobe for return */
1559         orig_p = __get_valid_kprobe(p);
1560         if (unlikely(orig_p == NULL))
1561                 return NULL;
1562 
1563         if (!kprobe_disabled(p)) {
1564                 /* Disable probe if it is a child probe */
1565                 if (p != orig_p)
1566                         p->flags |= KPROBE_FLAG_DISABLED;
1567 
1568                 /* Try to disarm and disable this/parent probe */
1569                 if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
1570                         disarm_kprobe(orig_p, true);
1571                         orig_p->flags |= KPROBE_FLAG_DISABLED;
1572                 }
1573         }
1574 
1575         return orig_p;
1576 }
1577 
1578 /*
1579  * Unregister a kprobe without a scheduler synchronization.
1580  */
1581 static int __unregister_kprobe_top(struct kprobe *p)
1582 {
1583         struct kprobe *ap, *list_p;
1584 
1585         /* Disable kprobe. This will disarm it if needed. */
1586         ap = __disable_kprobe(p);
1587         if (ap == NULL)
1588                 return -EINVAL;
1589 
1590         if (ap == p)
1591                 /*
1592                  * This probe is an independent(and non-optimized) kprobe
1593                  * (not an aggrprobe). Remove from the hash list.
1594                  */
1595                 goto disarmed;
1596 
1597         /* Following process expects this probe is an aggrprobe */
1598         WARN_ON(!kprobe_aggrprobe(ap));
1599 
1600         if (list_is_singular(&ap->list) && kprobe_disarmed(ap))
1601                 /*
1602                  * !disarmed could be happen if the probe is under delayed
1603                  * unoptimizing.
1604                  */
1605                 goto disarmed;
1606         else {
1607                 /* If disabling probe has special handlers, update aggrprobe */
1608                 if (p->break_handler && !kprobe_gone(p))
1609                         ap->break_handler = NULL;
1610                 if (p->post_handler && !kprobe_gone(p)) {
1611                         list_for_each_entry_rcu(list_p, &ap->list, list) {
1612                                 if ((list_p != p) && (list_p->post_handler))
1613                                         goto noclean;
1614                         }
1615                         ap->post_handler = NULL;
1616                 }
1617 noclean:
1618                 /*
1619                  * Remove from the aggrprobe: this path will do nothing in
1620                  * __unregister_kprobe_bottom().
1621                  */
1622                 list_del_rcu(&p->list);
1623                 if (!kprobe_disabled(ap) && !kprobes_all_disarmed)
1624                         /*
1625                          * Try to optimize this probe again, because post
1626                          * handler may have been changed.
1627                          */
1628                         optimize_kprobe(ap);
1629         }
1630         return 0;
1631 
1632 disarmed:
1633         BUG_ON(!kprobe_disarmed(ap));
1634         hlist_del_rcu(&ap->hlist);
1635         return 0;
1636 }
1637 
1638 static void __unregister_kprobe_bottom(struct kprobe *p)
1639 {
1640         struct kprobe *ap;
1641 
1642         if (list_empty(&p->list))
1643                 /* This is an independent kprobe */
1644                 arch_remove_kprobe(p);
1645         else if (list_is_singular(&p->list)) {
1646                 /* This is the last child of an aggrprobe */
1647                 ap = list_entry(p->list.next, struct kprobe, list);
1648                 list_del(&p->list);
1649                 free_aggr_kprobe(ap);
1650         }
1651         /* Otherwise, do nothing. */
1652 }
1653 
1654 int register_kprobes(struct kprobe **kps, int num)
1655 {
1656         int i, ret = 0;
1657 
1658         if (num <= 0)
1659                 return -EINVAL;
1660         for (i = 0; i < num; i++) {
1661                 ret = register_kprobe(kps[i]);
1662                 if (ret < 0) {
1663                         if (i > 0)
1664                                 unregister_kprobes(kps, i);
1665                         break;
1666                 }
1667         }
1668         return ret;
1669 }
1670 EXPORT_SYMBOL_GPL(register_kprobes);
1671 
1672 void unregister_kprobe(struct kprobe *p)
1673 {
1674         unregister_kprobes(&p, 1);
1675 }
1676 EXPORT_SYMBOL_GPL(unregister_kprobe);
1677 
1678 void unregister_kprobes(struct kprobe **kps, int num)
1679 {
1680         int i;
1681 
1682         if (num <= 0)
1683                 return;
1684         mutex_lock(&kprobe_mutex);
1685         for (i = 0; i < num; i++)
1686                 if (__unregister_kprobe_top(kps[i]) < 0)
1687                         kps[i]->addr = NULL;
1688         mutex_unlock(&kprobe_mutex);
1689 
1690         synchronize_sched();
1691         for (i = 0; i < num; i++)
1692                 if (kps[i]->addr)
1693                         __unregister_kprobe_bottom(kps[i]);
1694 }
1695 EXPORT_SYMBOL_GPL(unregister_kprobes);
1696 
1697 static struct notifier_block kprobe_exceptions_nb = {
1698         .notifier_call = kprobe_exceptions_notify,
1699         .priority = 0x7fffffff /* we need to be notified first */
1700 };
1701 
1702 unsigned long __weak arch_deref_entry_point(void *entry)
1703 {
1704         return (unsigned long)entry;
1705 }
1706 
1707 int register_jprobes(struct jprobe **jps, int num)
1708 {
1709         struct jprobe *jp;
1710         int ret = 0, i;
1711 
1712         if (num <= 0)
1713                 return -EINVAL;
1714         for (i = 0; i < num; i++) {
1715                 unsigned long addr, offset;
1716                 jp = jps[i];
1717                 addr = arch_deref_entry_point(jp->entry);
1718 
1719                 /* Verify probepoint is a function entry point */
1720                 if (kallsyms_lookup_size_offset(addr, NULL, &offset) &&
1721                     offset == 0) {
1722                         jp->kp.pre_handler = setjmp_pre_handler;
1723                         jp->kp.break_handler = longjmp_break_handler;
1724                         ret = register_kprobe(&jp->kp);
1725                 } else
1726                         ret = -EINVAL;
1727 
1728                 if (ret < 0) {
1729                         if (i > 0)
1730                                 unregister_jprobes(jps, i);
1731                         break;
1732                 }
1733         }
1734         return ret;
1735 }
1736 EXPORT_SYMBOL_GPL(register_jprobes);
1737 
1738 int register_jprobe(struct jprobe *jp)
1739 {
1740         return register_jprobes(&jp, 1);
1741 }
1742 EXPORT_SYMBOL_GPL(register_jprobe);
1743 
1744 void unregister_jprobe(struct jprobe *jp)
1745 {
1746         unregister_jprobes(&jp, 1);
1747 }
1748 EXPORT_SYMBOL_GPL(unregister_jprobe);
1749 
1750 void unregister_jprobes(struct jprobe **jps, int num)
1751 {
1752         int i;
1753 
1754         if (num <= 0)
1755                 return;
1756         mutex_lock(&kprobe_mutex);
1757         for (i = 0; i < num; i++)
1758                 if (__unregister_kprobe_top(&jps[i]->kp) < 0)
1759                         jps[i]->kp.addr = NULL;
1760         mutex_unlock(&kprobe_mutex);
1761 
1762         synchronize_sched();
1763         for (i = 0; i < num; i++) {
1764                 if (jps[i]->kp.addr)
1765                         __unregister_kprobe_bottom(&jps[i]->kp);
1766         }
1767 }
1768 EXPORT_SYMBOL_GPL(unregister_jprobes);
1769 
1770 #ifdef CONFIG_KRETPROBES
1771 /*
1772  * This kprobe pre_handler is registered with every kretprobe. When probe
1773  * hits it will set up the return probe.
1774  */
1775 static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
1776 {
1777         struct kretprobe *rp = container_of(p, struct kretprobe, kp);
1778         unsigned long hash, flags = 0;
1779         struct kretprobe_instance *ri;
1780 
1781         /*
1782          * To avoid deadlocks, prohibit return probing in NMI contexts,
1783          * just skip the probe and increase the (inexact) 'nmissed'
1784          * statistical counter, so that the user is informed that
1785          * something happened:
1786          */
1787         if (unlikely(in_nmi())) {
1788                 rp->nmissed++;
1789                 return 0;
1790         }
1791 
1792         /* TODO: consider to only swap the RA after the last pre_handler fired */
1793         hash = hash_ptr(current, KPROBE_HASH_BITS);
1794         raw_spin_lock_irqsave(&rp->lock, flags);
1795         if (!hlist_empty(&rp->free_instances)) {
1796                 ri = hlist_entry(rp->free_instances.first,
1797                                 struct kretprobe_instance, hlist);
1798                 hlist_del(&ri->hlist);
1799                 raw_spin_unlock_irqrestore(&rp->lock, flags);
1800 
1801                 ri->rp = rp;
1802                 ri->task = current;
1803 
1804                 if (rp->entry_handler && rp->entry_handler(ri, regs)) {
1805                         raw_spin_lock_irqsave(&rp->lock, flags);
1806                         hlist_add_head(&ri->hlist, &rp->free_instances);
1807                         raw_spin_unlock_irqrestore(&rp->lock, flags);
1808                         return 0;
1809                 }
1810 
1811                 arch_prepare_kretprobe(ri, regs);
1812 
1813                 /* XXX(hch): why is there no hlist_move_head? */
1814                 INIT_HLIST_NODE(&ri->hlist);
1815                 kretprobe_table_lock(hash, &flags);
1816                 hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
1817                 kretprobe_table_unlock(hash, &flags);
1818         } else {
1819                 rp->nmissed++;
1820                 raw_spin_unlock_irqrestore(&rp->lock, flags);
1821         }
1822         return 0;
1823 }
1824 NOKPROBE_SYMBOL(pre_handler_kretprobe);
1825 
1826 int register_kretprobe(struct kretprobe *rp)
1827 {
1828         int ret = 0;
1829         struct kretprobe_instance *inst;
1830         int i;
1831         void *addr;
1832 
1833         if (kretprobe_blacklist_size) {
1834                 addr = kprobe_addr(&rp->kp);
1835                 if (IS_ERR(addr))
1836                         return PTR_ERR(addr);
1837 
1838                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1839                         if (kretprobe_blacklist[i].addr == addr)
1840                                 return -EINVAL;
1841                 }
1842         }
1843 
1844         rp->kp.pre_handler = pre_handler_kretprobe;
1845         rp->kp.post_handler = NULL;
1846         rp->kp.fault_handler = NULL;
1847         rp->kp.break_handler = NULL;
1848 
1849         /* Pre-allocate memory for max kretprobe instances */
1850         if (rp->maxactive <= 0) {
1851 #ifdef CONFIG_PREEMPT
1852                 rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
1853 #else
1854                 rp->maxactive = num_possible_cpus();
1855 #endif
1856         }
1857         raw_spin_lock_init(&rp->lock);
1858         INIT_HLIST_HEAD(&rp->free_instances);
1859         for (i = 0; i < rp->maxactive; i++) {
1860                 inst = kmalloc(sizeof(struct kretprobe_instance) +
1861                                rp->data_size, GFP_KERNEL);
1862                 if (inst == NULL) {
1863                         free_rp_inst(rp);
1864                         return -ENOMEM;
1865                 }
1866                 INIT_HLIST_NODE(&inst->hlist);
1867                 hlist_add_head(&inst->hlist, &rp->free_instances);
1868         }
1869 
1870         rp->nmissed = 0;
1871         /* Establish function entry probe point */
1872         ret = register_kprobe(&rp->kp);
1873         if (ret != 0)
1874                 free_rp_inst(rp);
1875         return ret;
1876 }
1877 EXPORT_SYMBOL_GPL(register_kretprobe);
1878 
1879 int register_kretprobes(struct kretprobe **rps, int num)
1880 {
1881         int ret = 0, i;
1882 
1883         if (num <= 0)
1884                 return -EINVAL;
1885         for (i = 0; i < num; i++) {
1886                 ret = register_kretprobe(rps[i]);
1887                 if (ret < 0) {
1888                         if (i > 0)
1889                                 unregister_kretprobes(rps, i);
1890                         break;
1891                 }
1892         }
1893         return ret;
1894 }
1895 EXPORT_SYMBOL_GPL(register_kretprobes);
1896 
1897 void unregister_kretprobe(struct kretprobe *rp)
1898 {
1899         unregister_kretprobes(&rp, 1);
1900 }
1901 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1902 
1903 void unregister_kretprobes(struct kretprobe **rps, int num)
1904 {
1905         int i;
1906 
1907         if (num <= 0)
1908                 return;
1909         mutex_lock(&kprobe_mutex);
1910         for (i = 0; i < num; i++)
1911                 if (__unregister_kprobe_top(&rps[i]->kp) < 0)
1912                         rps[i]->kp.addr = NULL;
1913         mutex_unlock(&kprobe_mutex);
1914 
1915         synchronize_sched();
1916         for (i = 0; i < num; i++) {
1917                 if (rps[i]->kp.addr) {
1918                         __unregister_kprobe_bottom(&rps[i]->kp);
1919                         cleanup_rp_inst(rps[i]);
1920                 }
1921         }
1922 }
1923 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1924 
1925 #else /* CONFIG_KRETPROBES */
1926 int register_kretprobe(struct kretprobe *rp)
1927 {
1928         return -ENOSYS;
1929 }
1930 EXPORT_SYMBOL_GPL(register_kretprobe);
1931 
1932 int register_kretprobes(struct kretprobe **rps, int num)
1933 {
1934         return -ENOSYS;
1935 }
1936 EXPORT_SYMBOL_GPL(register_kretprobes);
1937 
1938 void unregister_kretprobe(struct kretprobe *rp)
1939 {
1940 }
1941 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1942 
1943 void unregister_kretprobes(struct kretprobe **rps, int num)
1944 {
1945 }
1946 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1947 
1948 static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
1949 {
1950         return 0;
1951 }
1952 NOKPROBE_SYMBOL(pre_handler_kretprobe);
1953 
1954 #endif /* CONFIG_KRETPROBES */
1955 
1956 /* Set the kprobe gone and remove its instruction buffer. */
1957 static void kill_kprobe(struct kprobe *p)
1958 {
1959         struct kprobe *kp;
1960 
1961         p->flags |= KPROBE_FLAG_GONE;
1962         if (kprobe_aggrprobe(p)) {
1963                 /*
1964                  * If this is an aggr_kprobe, we have to list all the
1965                  * chained probes and mark them GONE.
1966                  */
1967                 list_for_each_entry_rcu(kp, &p->list, list)
1968                         kp->flags |= KPROBE_FLAG_GONE;
1969                 p->post_handler = NULL;
1970                 p->break_handler = NULL;
1971                 kill_optimized_kprobe(p);
1972         }
1973         /*
1974          * Here, we can remove insn_slot safely, because no thread calls
1975          * the original probed function (which will be freed soon) any more.
1976          */
1977         arch_remove_kprobe(p);
1978 }
1979 
1980 /* Disable one kprobe */
1981 int disable_kprobe(struct kprobe *kp)
1982 {
1983         int ret = 0;
1984 
1985         mutex_lock(&kprobe_mutex);
1986 
1987         /* Disable this kprobe */
1988         if (__disable_kprobe(kp) == NULL)
1989                 ret = -EINVAL;
1990 
1991         mutex_unlock(&kprobe_mutex);
1992         return ret;
1993 }
1994 EXPORT_SYMBOL_GPL(disable_kprobe);
1995 
1996 /* Enable one kprobe */
1997 int enable_kprobe(struct kprobe *kp)
1998 {
1999         int ret = 0;
2000         struct kprobe *p;
2001 
2002         mutex_lock(&kprobe_mutex);
2003 
2004         /* Check whether specified probe is valid. */
2005         p = __get_valid_kprobe(kp);
2006         if (unlikely(p == NULL)) {
2007                 ret = -EINVAL;
2008                 goto out;
2009         }
2010 
2011         if (kprobe_gone(kp)) {
2012                 /* This kprobe has gone, we couldn't enable it. */
2013                 ret = -EINVAL;
2014                 goto out;
2015         }
2016 
2017         if (p != kp)
2018                 kp->flags &= ~KPROBE_FLAG_DISABLED;
2019 
2020         if (!kprobes_all_disarmed && kprobe_disabled(p)) {
2021                 p->flags &= ~KPROBE_FLAG_DISABLED;
2022                 arm_kprobe(p);
2023         }
2024 out:
2025         mutex_unlock(&kprobe_mutex);
2026         return ret;
2027 }
2028 EXPORT_SYMBOL_GPL(enable_kprobe);
2029 
2030 void dump_kprobe(struct kprobe *kp)
2031 {
2032         printk(KERN_WARNING "Dumping kprobe:\n");
2033         printk(KERN_WARNING "Name: %s\nAddress: %p\nOffset: %x\n",
2034                kp->symbol_name, kp->addr, kp->offset);
2035 }
2036 NOKPROBE_SYMBOL(dump_kprobe);
2037 
2038 /*
2039  * Lookup and populate the kprobe_blacklist.
2040  *
2041  * Unlike the kretprobe blacklist, we'll need to determine
2042  * the range of addresses that belong to the said functions,
2043  * since a kprobe need not necessarily be at the beginning
2044  * of a function.
2045  */
2046 static int __init populate_kprobe_blacklist(unsigned long *start,
2047                                              unsigned long *end)
2048 {
2049         unsigned long *iter;
2050         struct kprobe_blacklist_entry *ent;
2051         unsigned long entry, offset = 0, size = 0;
2052 
2053         for (iter = start; iter < end; iter++) {
2054                 entry = arch_deref_entry_point((void *)*iter);
2055 
2056                 if (!kernel_text_address(entry) ||
2057                     !kallsyms_lookup_size_offset(entry, &size, &offset)) {
2058                         pr_err("Failed to find blacklist at %p\n",
2059                                 (void *)entry);
2060                         continue;
2061                 }
2062 
2063                 ent = kmalloc(sizeof(*ent), GFP_KERNEL);
2064                 if (!ent)
2065                         return -ENOMEM;
2066                 ent->start_addr = entry;
2067                 ent->end_addr = entry + size;
2068                 INIT_LIST_HEAD(&ent->list);
2069                 list_add_tail(&ent->list, &kprobe_blacklist);
2070         }
2071         return 0;
2072 }
2073 
2074 /* Module notifier call back, checking kprobes on the module */
2075 static int kprobes_module_callback(struct notifier_block *nb,
2076                                    unsigned long val, void *data)
2077 {
2078         struct module *mod = data;
2079         struct hlist_head *head;
2080         struct kprobe *p;
2081         unsigned int i;
2082         int checkcore = (val == MODULE_STATE_GOING);
2083 
2084         if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
2085                 return NOTIFY_DONE;
2086 
2087         /*
2088          * When MODULE_STATE_GOING was notified, both of module .text and
2089          * .init.text sections would be freed. When MODULE_STATE_LIVE was
2090          * notified, only .init.text section would be freed. We need to
2091          * disable kprobes which have been inserted in the sections.
2092          */
2093         mutex_lock(&kprobe_mutex);
2094         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2095                 head = &kprobe_table[i];
2096                 hlist_for_each_entry_rcu(p, head, hlist)
2097                         if (within_module_init((unsigned long)p->addr, mod) ||
2098                             (checkcore &&
2099                              within_module_core((unsigned long)p->addr, mod))) {
2100                                 /*
2101                                  * The vaddr this probe is installed will soon
2102                                  * be vfreed buy not synced to disk. Hence,
2103                                  * disarming the breakpoint isn't needed.
2104                                  */
2105                                 kill_kprobe(p);
2106                         }
2107         }
2108         mutex_unlock(&kprobe_mutex);
2109         return NOTIFY_DONE;
2110 }
2111 
2112 static struct notifier_block kprobe_module_nb = {
2113         .notifier_call = kprobes_module_callback,
2114         .priority = 0
2115 };
2116 
2117 /* Markers of _kprobe_blacklist section */
2118 extern unsigned long __start_kprobe_blacklist[];
2119 extern unsigned long __stop_kprobe_blacklist[];
2120 
2121 static int __init init_kprobes(void)
2122 {
2123         int i, err = 0;
2124 
2125         /* FIXME allocate the probe table, currently defined statically */
2126         /* initialize all list heads */
2127         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2128                 INIT_HLIST_HEAD(&kprobe_table[i]);
2129                 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
2130                 raw_spin_lock_init(&(kretprobe_table_locks[i].lock));
2131         }
2132 
2133         err = populate_kprobe_blacklist(__start_kprobe_blacklist,
2134                                         __stop_kprobe_blacklist);
2135         if (err) {
2136                 pr_err("kprobes: failed to populate blacklist: %d\n", err);
2137                 pr_err("Please take care of using kprobes.\n");
2138         }
2139 
2140         if (kretprobe_blacklist_size) {
2141                 /* lookup the function address from its name */
2142                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
2143                         kprobe_lookup_name(kretprobe_blacklist[i].name,
2144                                            kretprobe_blacklist[i].addr);
2145                         if (!kretprobe_blacklist[i].addr)
2146                                 printk("kretprobe: lookup failed: %s\n",
2147                                        kretprobe_blacklist[i].name);
2148                 }
2149         }
2150 
2151 #if defined(CONFIG_OPTPROBES)
2152 #if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
2153         /* Init kprobe_optinsn_slots */
2154         kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
2155 #endif
2156         /* By default, kprobes can be optimized */
2157         kprobes_allow_optimization = true;
2158 #endif
2159 
2160         /* By default, kprobes are armed */
2161         kprobes_all_disarmed = false;
2162 
2163         err = arch_init_kprobes();
2164         if (!err)
2165                 err = register_die_notifier(&kprobe_exceptions_nb);
2166         if (!err)
2167                 err = register_module_notifier(&kprobe_module_nb);
2168 
2169         kprobes_initialized = (err == 0);
2170 
2171         if (!err)
2172                 init_test_probes();
2173         return err;
2174 }
2175 
2176 #ifdef CONFIG_DEBUG_FS
2177 static void report_probe(struct seq_file *pi, struct kprobe *p,
2178                 const char *sym, int offset, char *modname, struct kprobe *pp)
2179 {
2180         char *kprobe_type;
2181 
2182         if (p->pre_handler == pre_handler_kretprobe)
2183                 kprobe_type = "r";
2184         else if (p->pre_handler == setjmp_pre_handler)
2185                 kprobe_type = "j";
2186         else
2187                 kprobe_type = "k";
2188 
2189         if (sym)
2190                 seq_printf(pi, "%p  %s  %s+0x%x  %s ",
2191                         p->addr, kprobe_type, sym, offset,
2192                         (modname ? modname : " "));
2193         else
2194                 seq_printf(pi, "%p  %s  %p ",
2195                         p->addr, kprobe_type, p->addr);
2196 
2197         if (!pp)
2198                 pp = p;
2199         seq_printf(pi, "%s%s%s%s\n",
2200                 (kprobe_gone(p) ? "[GONE]" : ""),
2201                 ((kprobe_disabled(p) && !kprobe_gone(p)) ?  "[DISABLED]" : ""),
2202                 (kprobe_optimized(pp) ? "[OPTIMIZED]" : ""),
2203                 (kprobe_ftrace(pp) ? "[FTRACE]" : ""));
2204 }
2205 
2206 static void *kprobe_seq_start(struct seq_file *f, loff_t *pos)
2207 {
2208         return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
2209 }
2210 
2211 static void *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
2212 {
2213         (*pos)++;
2214         if (*pos >= KPROBE_TABLE_SIZE)
2215                 return NULL;
2216         return pos;
2217 }
2218 
2219 static void kprobe_seq_stop(struct seq_file *f, void *v)
2220 {
2221         /* Nothing to do */
2222 }
2223 
2224 static int show_kprobe_addr(struct seq_file *pi, void *v)
2225 {
2226         struct hlist_head *head;
2227         struct kprobe *p, *kp;
2228         const char *sym = NULL;
2229         unsigned int i = *(loff_t *) v;
2230         unsigned long offset = 0;
2231         char *modname, namebuf[KSYM_NAME_LEN];
2232 
2233         head = &kprobe_table[i];
2234         preempt_disable();
2235         hlist_for_each_entry_rcu(p, head, hlist) {
2236                 sym = kallsyms_lookup((unsigned long)p->addr, NULL,
2237                                         &offset, &modname, namebuf);
2238                 if (kprobe_aggrprobe(p)) {
2239                         list_for_each_entry_rcu(kp, &p->list, list)
2240                                 report_probe(pi, kp, sym, offset, modname, p);
2241                 } else
2242                         report_probe(pi, p, sym, offset, modname, NULL);
2243         }
2244         preempt_enable();
2245         return 0;
2246 }
2247 
2248 static const struct seq_operations kprobes_seq_ops = {
2249         .start = kprobe_seq_start,
2250         .next  = kprobe_seq_next,
2251         .stop  = kprobe_seq_stop,
2252         .show  = show_kprobe_addr
2253 };
2254 
2255 static int kprobes_open(struct inode *inode, struct file *filp)
2256 {
2257         return seq_open(filp, &kprobes_seq_ops);
2258 }
2259 
2260 static const struct file_operations debugfs_kprobes_operations = {
2261         .open           = kprobes_open,
2262         .read           = seq_read,
2263         .llseek         = seq_lseek,
2264         .release        = seq_release,
2265 };
2266 
2267 /* kprobes/blacklist -- shows which functions can not be probed */
2268 static void *kprobe_blacklist_seq_start(struct seq_file *m, loff_t *pos)
2269 {
2270         return seq_list_start(&kprobe_blacklist, *pos);
2271 }
2272 
2273 static void *kprobe_blacklist_seq_next(struct seq_file *m, void *v, loff_t *pos)
2274 {
2275         return seq_list_next(v, &kprobe_blacklist, pos);
2276 }
2277 
2278 static int kprobe_blacklist_seq_show(struct seq_file *m, void *v)
2279 {
2280         struct kprobe_blacklist_entry *ent =
2281                 list_entry(v, struct kprobe_blacklist_entry, list);
2282 
2283         seq_printf(m, "0x%p-0x%p\t%ps\n", (void *)ent->start_addr,
2284                    (void *)ent->end_addr, (void *)ent->start_addr);
2285         return 0;
2286 }
2287 
2288 static const struct seq_operations kprobe_blacklist_seq_ops = {
2289         .start = kprobe_blacklist_seq_start,
2290         .next  = kprobe_blacklist_seq_next,
2291         .stop  = kprobe_seq_stop,       /* Reuse void function */
2292         .show  = kprobe_blacklist_seq_show,
2293 };
2294 
2295 static int kprobe_blacklist_open(struct inode *inode, struct file *filp)
2296 {
2297         return seq_open(filp, &kprobe_blacklist_seq_ops);
2298 }
2299 
2300 static const struct file_operations debugfs_kprobe_blacklist_ops = {
2301         .open           = kprobe_blacklist_open,
2302         .read           = seq_read,
2303         .llseek         = seq_lseek,
2304         .release        = seq_release,
2305 };
2306 
2307 static void arm_all_kprobes(void)
2308 {
2309         struct hlist_head *head;
2310         struct kprobe *p;
2311         unsigned int i;
2312 
2313         mutex_lock(&kprobe_mutex);
2314 
2315         /* If kprobes are armed, just return */
2316         if (!kprobes_all_disarmed)
2317                 goto already_enabled;
2318 
2319         /* Arming kprobes doesn't optimize kprobe itself */
2320         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2321                 head = &kprobe_table[i];
2322                 hlist_for_each_entry_rcu(p, head, hlist)
2323                         if (!kprobe_disabled(p))
2324                                 arm_kprobe(p);
2325         }
2326 
2327         kprobes_all_disarmed = false;
2328         printk(KERN_INFO "Kprobes globally enabled\n");
2329 
2330 already_enabled:
2331         mutex_unlock(&kprobe_mutex);
2332         return;
2333 }
2334 
2335 static void disarm_all_kprobes(void)
2336 {
2337         struct hlist_head *head;
2338         struct kprobe *p;
2339         unsigned int i;
2340 
2341         mutex_lock(&kprobe_mutex);
2342 
2343         /* If kprobes are already disarmed, just return */
2344         if (kprobes_all_disarmed) {
2345                 mutex_unlock(&kprobe_mutex);
2346                 return;
2347         }
2348 
2349         kprobes_all_disarmed = true;
2350         printk(KERN_INFO "Kprobes globally disabled\n");
2351 
2352         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2353                 head = &kprobe_table[i];
2354                 hlist_for_each_entry_rcu(p, head, hlist) {
2355                         if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
2356                                 disarm_kprobe(p, false);
2357                 }
2358         }
2359         mutex_unlock(&kprobe_mutex);
2360 
2361         /* Wait for disarming all kprobes by optimizer */
2362         wait_for_kprobe_optimizer();
2363 }
2364 
2365 /*
2366  * XXX: The debugfs bool file interface doesn't allow for callbacks
2367  * when the bool state is switched. We can reuse that facility when
2368  * available
2369  */
2370 static ssize_t read_enabled_file_bool(struct file *file,
2371                char __user *user_buf, size_t count, loff_t *ppos)
2372 {
2373         char buf[3];
2374 
2375         if (!kprobes_all_disarmed)
2376                 buf[0] = '1';
2377         else
2378                 buf[0] = '';
2379         buf[1] = '\n';
2380         buf[2] = 0x00;
2381         return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
2382 }
2383 
2384 static ssize_t write_enabled_file_bool(struct file *file,
2385                const char __user *user_buf, size_t count, loff_t *ppos)
2386 {
2387         char buf[32];
2388         size_t buf_size;
2389 
2390         buf_size = min(count, (sizeof(buf)-1));
2391         if (copy_from_user(buf, user_buf, buf_size))
2392                 return -EFAULT;
2393 
2394         buf[buf_size] = '\0';
2395         switch (buf[0]) {
2396         case 'y':
2397         case 'Y':
2398         case '1':
2399                 arm_all_kprobes();
2400                 break;
2401         case 'n':
2402         case 'N':
2403         case '':
2404                 disarm_all_kprobes();
2405                 break;
2406         default:
2407                 return -EINVAL;
2408         }
2409 
2410         return count;
2411 }
2412 
2413 static const struct file_operations fops_kp = {
2414         .read =         read_enabled_file_bool,
2415         .write =        write_enabled_file_bool,
2416         .llseek =       default_llseek,
2417 };
2418 
2419 static int __init debugfs_kprobe_init(void)
2420 {
2421         struct dentry *dir, *file;
2422         unsigned int value = 1;
2423 
2424         dir = debugfs_create_dir("kprobes", NULL);
2425         if (!dir)
2426                 return -ENOMEM;
2427 
2428         file = debugfs_create_file("list", 0444, dir, NULL,
2429                                 &debugfs_kprobes_operations);
2430         if (!file)
2431                 goto error;
2432 
2433         file = debugfs_create_file("enabled", 0600, dir,
2434                                         &value, &fops_kp);
2435         if (!file)
2436                 goto error;
2437 
2438         file = debugfs_create_file("blacklist", 0444, dir, NULL,
2439                                 &debugfs_kprobe_blacklist_ops);
2440         if (!file)
2441                 goto error;
2442 
2443         return 0;
2444 
2445 error:
2446         debugfs_remove(dir);
2447         return -ENOMEM;
2448 }
2449 
2450 late_initcall(debugfs_kprobe_init);
2451 #endif /* CONFIG_DEBUG_FS */
2452 
2453 module_init(init_kprobes);
2454 
2455 /* defined in arch/.../kernel/kprobes.c */
2456 EXPORT_SYMBOL_GPL(jprobe_return);
2457 

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