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

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