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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 void __weak 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 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 int 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         if (!kprobe_optready(ap))
685                 return -EINVAL;
686 
687         optimize_kprobe(ap);
688         return 0;
689 }
690 
691 /* Remove optimized instructions */
692 static void kill_optimized_kprobe(struct kprobe *p)
693 {
694         struct optimized_kprobe *op;
695 
696         op = container_of(p, struct optimized_kprobe, kp);
697         if (!list_empty(&op->list))
698                 /* Dequeue from the (un)optimization queue */
699                 list_del_init(&op->list);
700         op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
701 
702         if (kprobe_unused(p)) {
703                 /* Enqueue if it is unused */
704                 list_add(&op->list, &freeing_list);
705                 /*
706                  * Remove unused probes from the hash list. After waiting
707                  * for synchronization, this probe is reclaimed.
708                  * (reclaiming is done by do_free_cleaned_kprobes().)
709                  */
710                 hlist_del_rcu(&op->kp.hlist);
711         }
712 
713         /* Don't touch the code, because it is already freed. */
714         arch_remove_optimized_kprobe(op);
715 }
716 
717 /* Try to prepare optimized instructions */
718 static void prepare_optimized_kprobe(struct kprobe *p)
719 {
720         struct optimized_kprobe *op;
721 
722         op = container_of(p, struct optimized_kprobe, kp);
723         arch_prepare_optimized_kprobe(op);
724 }
725 
726 /* Allocate new optimized_kprobe and try to prepare optimized instructions */
727 static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
728 {
729         struct optimized_kprobe *op;
730 
731         op = kzalloc(sizeof(struct optimized_kprobe), GFP_KERNEL);
732         if (!op)
733                 return NULL;
734 
735         INIT_LIST_HEAD(&op->list);
736         op->kp.addr = p->addr;
737         arch_prepare_optimized_kprobe(op);
738 
739         return &op->kp;
740 }
741 
742 static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p);
743 
744 /*
745  * Prepare an optimized_kprobe and optimize it
746  * NOTE: p must be a normal registered kprobe
747  */
748 static void try_to_optimize_kprobe(struct kprobe *p)
749 {
750         struct kprobe *ap;
751         struct optimized_kprobe *op;
752 
753         /* Impossible to optimize ftrace-based kprobe */
754         if (kprobe_ftrace(p))
755                 return;
756 
757         /* For preparing optimization, jump_label_text_reserved() is called */
758         jump_label_lock();
759         mutex_lock(&text_mutex);
760 
761         ap = alloc_aggr_kprobe(p);
762         if (!ap)
763                 goto out;
764 
765         op = container_of(ap, struct optimized_kprobe, kp);
766         if (!arch_prepared_optinsn(&op->optinsn)) {
767                 /* If failed to setup optimizing, fallback to kprobe */
768                 arch_remove_optimized_kprobe(op);
769                 kfree(op);
770                 goto out;
771         }
772 
773         init_aggr_kprobe(ap, p);
774         optimize_kprobe(ap);    /* This just kicks optimizer thread */
775 
776 out:
777         mutex_unlock(&text_mutex);
778         jump_label_unlock();
779 }
780 
781 #ifdef CONFIG_SYSCTL
782 static void optimize_all_kprobes(void)
783 {
784         struct hlist_head *head;
785         struct kprobe *p;
786         unsigned int i;
787 
788         mutex_lock(&kprobe_mutex);
789         /* If optimization is already allowed, just return */
790         if (kprobes_allow_optimization)
791                 goto out;
792 
793         kprobes_allow_optimization = true;
794         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
795                 head = &kprobe_table[i];
796                 hlist_for_each_entry_rcu(p, head, hlist)
797                         if (!kprobe_disabled(p))
798                                 optimize_kprobe(p);
799         }
800         printk(KERN_INFO "Kprobes globally optimized\n");
801 out:
802         mutex_unlock(&kprobe_mutex);
803 }
804 
805 static void unoptimize_all_kprobes(void)
806 {
807         struct hlist_head *head;
808         struct kprobe *p;
809         unsigned int i;
810 
811         mutex_lock(&kprobe_mutex);
812         /* If optimization is already prohibited, just return */
813         if (!kprobes_allow_optimization) {
814                 mutex_unlock(&kprobe_mutex);
815                 return;
816         }
817 
818         kprobes_allow_optimization = false;
819         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
820                 head = &kprobe_table[i];
821                 hlist_for_each_entry_rcu(p, head, hlist) {
822                         if (!kprobe_disabled(p))
823                                 unoptimize_kprobe(p, false);
824                 }
825         }
826         mutex_unlock(&kprobe_mutex);
827 
828         /* Wait for unoptimizing completion */
829         wait_for_kprobe_optimizer();
830         printk(KERN_INFO "Kprobes globally unoptimized\n");
831 }
832 
833 static DEFINE_MUTEX(kprobe_sysctl_mutex);
834 int sysctl_kprobes_optimization;
835 int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
836                                       void __user *buffer, size_t *length,
837                                       loff_t *ppos)
838 {
839         int ret;
840 
841         mutex_lock(&kprobe_sysctl_mutex);
842         sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0;
843         ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
844 
845         if (sysctl_kprobes_optimization)
846                 optimize_all_kprobes();
847         else
848                 unoptimize_all_kprobes();
849         mutex_unlock(&kprobe_sysctl_mutex);
850 
851         return ret;
852 }
853 #endif /* CONFIG_SYSCTL */
854 
855 /* Put a breakpoint for a probe. Must be called with text_mutex locked */
856 static void __arm_kprobe(struct kprobe *p)
857 {
858         struct kprobe *_p;
859 
860         /* Check collision with other optimized kprobes */
861         _p = get_optimized_kprobe((unsigned long)p->addr);
862         if (unlikely(_p))
863                 /* Fallback to unoptimized kprobe */
864                 unoptimize_kprobe(_p, true);
865 
866         arch_arm_kprobe(p);
867         optimize_kprobe(p);     /* Try to optimize (add kprobe to a list) */
868 }
869 
870 /* Remove the breakpoint of a probe. Must be called with text_mutex locked */
871 static void __disarm_kprobe(struct kprobe *p, bool reopt)
872 {
873         struct kprobe *_p;
874 
875         unoptimize_kprobe(p, false);    /* Try to unoptimize */
876 
877         if (!kprobe_queued(p)) {
878                 arch_disarm_kprobe(p);
879                 /* If another kprobe was blocked, optimize it. */
880                 _p = get_optimized_kprobe((unsigned long)p->addr);
881                 if (unlikely(_p) && reopt)
882                         optimize_kprobe(_p);
883         }
884         /* TODO: reoptimize others after unoptimized this probe */
885 }
886 
887 #else /* !CONFIG_OPTPROBES */
888 
889 #define optimize_kprobe(p)                      do {} while (0)
890 #define unoptimize_kprobe(p, f)                 do {} while (0)
891 #define kill_optimized_kprobe(p)                do {} while (0)
892 #define prepare_optimized_kprobe(p)             do {} while (0)
893 #define try_to_optimize_kprobe(p)               do {} while (0)
894 #define __arm_kprobe(p)                         arch_arm_kprobe(p)
895 #define __disarm_kprobe(p, o)                   arch_disarm_kprobe(p)
896 #define kprobe_disarmed(p)                      kprobe_disabled(p)
897 #define wait_for_kprobe_optimizer()             do {} while (0)
898 
899 static int reuse_unused_kprobe(struct kprobe *ap)
900 {
901         /*
902          * If the optimized kprobe is NOT supported, the aggr kprobe is
903          * released at the same time that the last aggregated kprobe is
904          * unregistered.
905          * Thus there should be no chance to reuse unused kprobe.
906          */
907         printk(KERN_ERR "Error: There should be no unused kprobe here.\n");
908         return -EINVAL;
909 }
910 
911 static void free_aggr_kprobe(struct kprobe *p)
912 {
913         arch_remove_kprobe(p);
914         kfree(p);
915 }
916 
917 static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
918 {
919         return kzalloc(sizeof(struct kprobe), GFP_KERNEL);
920 }
921 #endif /* CONFIG_OPTPROBES */
922 
923 #ifdef CONFIG_KPROBES_ON_FTRACE
924 static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
925         .func = kprobe_ftrace_handler,
926         .flags = FTRACE_OPS_FL_SAVE_REGS,
927 };
928 static int kprobe_ftrace_enabled;
929 
930 /* Must ensure p->addr is really on ftrace */
931 static int prepare_kprobe(struct kprobe *p)
932 {
933         if (!kprobe_ftrace(p))
934                 return arch_prepare_kprobe(p);
935 
936         return arch_prepare_kprobe_ftrace(p);
937 }
938 
939 /* Caller must lock kprobe_mutex */
940 static void arm_kprobe_ftrace(struct kprobe *p)
941 {
942         int ret;
943 
944         ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
945                                    (unsigned long)p->addr, 0, 0);
946         WARN(ret < 0, "Failed to arm kprobe-ftrace at %p (%d)\n", p->addr, ret);
947         kprobe_ftrace_enabled++;
948         if (kprobe_ftrace_enabled == 1) {
949                 ret = register_ftrace_function(&kprobe_ftrace_ops);
950                 WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
951         }
952 }
953 
954 /* Caller must lock kprobe_mutex */
955 static void disarm_kprobe_ftrace(struct kprobe *p)
956 {
957         int ret;
958 
959         kprobe_ftrace_enabled--;
960         if (kprobe_ftrace_enabled == 0) {
961                 ret = unregister_ftrace_function(&kprobe_ftrace_ops);
962                 WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
963         }
964         ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
965                            (unsigned long)p->addr, 1, 0);
966         WARN(ret < 0, "Failed to disarm kprobe-ftrace at %p (%d)\n", p->addr, ret);
967 }
968 #else   /* !CONFIG_KPROBES_ON_FTRACE */
969 #define prepare_kprobe(p)       arch_prepare_kprobe(p)
970 #define arm_kprobe_ftrace(p)    do {} while (0)
971 #define disarm_kprobe_ftrace(p) do {} while (0)
972 #endif
973 
974 /* Arm a kprobe with text_mutex */
975 static void arm_kprobe(struct kprobe *kp)
976 {
977         if (unlikely(kprobe_ftrace(kp))) {
978                 arm_kprobe_ftrace(kp);
979                 return;
980         }
981         /*
982          * Here, since __arm_kprobe() doesn't use stop_machine(),
983          * this doesn't cause deadlock on text_mutex. So, we don't
984          * need get_online_cpus().
985          */
986         mutex_lock(&text_mutex);
987         __arm_kprobe(kp);
988         mutex_unlock(&text_mutex);
989 }
990 
991 /* Disarm a kprobe with text_mutex */
992 static void disarm_kprobe(struct kprobe *kp, bool reopt)
993 {
994         if (unlikely(kprobe_ftrace(kp))) {
995                 disarm_kprobe_ftrace(kp);
996                 return;
997         }
998         /* Ditto */
999         mutex_lock(&text_mutex);
1000         __disarm_kprobe(kp, reopt);
1001         mutex_unlock(&text_mutex);
1002 }
1003 
1004 /*
1005  * Aggregate handlers for multiple kprobes support - these handlers
1006  * take care of invoking the individual kprobe handlers on p->list
1007  */
1008 static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
1009 {
1010         struct kprobe *kp;
1011 
1012         list_for_each_entry_rcu(kp, &p->list, list) {
1013                 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
1014                         set_kprobe_instance(kp);
1015                         if (kp->pre_handler(kp, regs))
1016                                 return 1;
1017                 }
1018                 reset_kprobe_instance();
1019         }
1020         return 0;
1021 }
1022 NOKPROBE_SYMBOL(aggr_pre_handler);
1023 
1024 static void aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
1025                               unsigned long flags)
1026 {
1027         struct kprobe *kp;
1028 
1029         list_for_each_entry_rcu(kp, &p->list, list) {
1030                 if (kp->post_handler && likely(!kprobe_disabled(kp))) {
1031                         set_kprobe_instance(kp);
1032                         kp->post_handler(kp, regs, flags);
1033                         reset_kprobe_instance();
1034                 }
1035         }
1036 }
1037 NOKPROBE_SYMBOL(aggr_post_handler);
1038 
1039 static int aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
1040                               int trapnr)
1041 {
1042         struct kprobe *cur = __this_cpu_read(kprobe_instance);
1043 
1044         /*
1045          * if we faulted "during" the execution of a user specified
1046          * probe handler, invoke just that probe's fault handler
1047          */
1048         if (cur && cur->fault_handler) {
1049                 if (cur->fault_handler(cur, regs, trapnr))
1050                         return 1;
1051         }
1052         return 0;
1053 }
1054 NOKPROBE_SYMBOL(aggr_fault_handler);
1055 
1056 static int 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 NOKPROBE_SYMBOL(aggr_break_handler);
1069 
1070 /* Walks the list and increments nmissed count for multiprobe case */
1071 void kprobes_inc_nmissed_count(struct kprobe *p)
1072 {
1073         struct kprobe *kp;
1074         if (!kprobe_aggrprobe(p)) {
1075                 p->nmissed++;
1076         } else {
1077                 list_for_each_entry_rcu(kp, &p->list, list)
1078                         kp->nmissed++;
1079         }
1080         return;
1081 }
1082 NOKPROBE_SYMBOL(kprobes_inc_nmissed_count);
1083 
1084 void recycle_rp_inst(struct kretprobe_instance *ri,
1085                      struct hlist_head *head)
1086 {
1087         struct kretprobe *rp = ri->rp;
1088 
1089         /* remove rp inst off the rprobe_inst_table */
1090         hlist_del(&ri->hlist);
1091         INIT_HLIST_NODE(&ri->hlist);
1092         if (likely(rp)) {
1093                 raw_spin_lock(&rp->lock);
1094                 hlist_add_head(&ri->hlist, &rp->free_instances);
1095                 raw_spin_unlock(&rp->lock);
1096         } else
1097                 /* Unregistering */
1098                 hlist_add_head(&ri->hlist, head);
1099 }
1100 NOKPROBE_SYMBOL(recycle_rp_inst);
1101 
1102 void kretprobe_hash_lock(struct task_struct *tsk,
1103                          struct hlist_head **head, unsigned long *flags)
1104 __acquires(hlist_lock)
1105 {
1106         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1107         raw_spinlock_t *hlist_lock;
1108 
1109         *head = &kretprobe_inst_table[hash];
1110         hlist_lock = kretprobe_table_lock_ptr(hash);
1111         raw_spin_lock_irqsave(hlist_lock, *flags);
1112 }
1113 NOKPROBE_SYMBOL(kretprobe_hash_lock);
1114 
1115 static void kretprobe_table_lock(unsigned long hash,
1116                                  unsigned long *flags)
1117 __acquires(hlist_lock)
1118 {
1119         raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1120         raw_spin_lock_irqsave(hlist_lock, *flags);
1121 }
1122 NOKPROBE_SYMBOL(kretprobe_table_lock);
1123 
1124 void kretprobe_hash_unlock(struct task_struct *tsk,
1125                            unsigned long *flags)
1126 __releases(hlist_lock)
1127 {
1128         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1129         raw_spinlock_t *hlist_lock;
1130 
1131         hlist_lock = kretprobe_table_lock_ptr(hash);
1132         raw_spin_unlock_irqrestore(hlist_lock, *flags);
1133 }
1134 NOKPROBE_SYMBOL(kretprobe_hash_unlock);
1135 
1136 static void kretprobe_table_unlock(unsigned long hash,
1137                                    unsigned long *flags)
1138 __releases(hlist_lock)
1139 {
1140         raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1141         raw_spin_unlock_irqrestore(hlist_lock, *flags);
1142 }
1143 NOKPROBE_SYMBOL(kretprobe_table_unlock);
1144 
1145 /*
1146  * This function is called from finish_task_switch when task tk becomes dead,
1147  * so that we can recycle any function-return probe instances associated
1148  * with this task. These left over instances represent probed functions
1149  * that have been called but will never return.
1150  */
1151 void kprobe_flush_task(struct task_struct *tk)
1152 {
1153         struct kretprobe_instance *ri;
1154         struct hlist_head *head, empty_rp;
1155         struct hlist_node *tmp;
1156         unsigned long hash, flags = 0;
1157 
1158         if (unlikely(!kprobes_initialized))
1159                 /* Early boot.  kretprobe_table_locks not yet initialized. */
1160                 return;
1161 
1162         INIT_HLIST_HEAD(&empty_rp);
1163         hash = hash_ptr(tk, KPROBE_HASH_BITS);
1164         head = &kretprobe_inst_table[hash];
1165         kretprobe_table_lock(hash, &flags);
1166         hlist_for_each_entry_safe(ri, tmp, head, hlist) {
1167                 if (ri->task == tk)
1168                         recycle_rp_inst(ri, &empty_rp);
1169         }
1170         kretprobe_table_unlock(hash, &flags);
1171         hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
1172                 hlist_del(&ri->hlist);
1173                 kfree(ri);
1174         }
1175 }
1176 NOKPROBE_SYMBOL(kprobe_flush_task);
1177 
1178 static inline void free_rp_inst(struct kretprobe *rp)
1179 {
1180         struct kretprobe_instance *ri;
1181         struct hlist_node *next;
1182 
1183         hlist_for_each_entry_safe(ri, next, &rp->free_instances, hlist) {
1184                 hlist_del(&ri->hlist);
1185                 kfree(ri);
1186         }
1187 }
1188 
1189 static void cleanup_rp_inst(struct kretprobe *rp)
1190 {
1191         unsigned long flags, hash;
1192         struct kretprobe_instance *ri;
1193         struct hlist_node *next;
1194         struct hlist_head *head;
1195 
1196         /* No race here */
1197         for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
1198                 kretprobe_table_lock(hash, &flags);
1199                 head = &kretprobe_inst_table[hash];
1200                 hlist_for_each_entry_safe(ri, next, head, hlist) {
1201                         if (ri->rp == rp)
1202                                 ri->rp = NULL;
1203                 }
1204                 kretprobe_table_unlock(hash, &flags);
1205         }
1206         free_rp_inst(rp);
1207 }
1208 NOKPROBE_SYMBOL(cleanup_rp_inst);
1209 
1210 /*
1211 * Add the new probe to ap->list. Fail if this is the
1212 * second jprobe at the address - two jprobes can't coexist
1213 */
1214 static int add_new_kprobe(struct kprobe *ap, struct kprobe *p)
1215 {
1216         BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
1217 
1218         if (p->break_handler || p->post_handler)
1219                 unoptimize_kprobe(ap, true);    /* Fall back to normal kprobe */
1220 
1221         if (p->break_handler) {
1222                 if (ap->break_handler)
1223                         return -EEXIST;
1224                 list_add_tail_rcu(&p->list, &ap->list);
1225                 ap->break_handler = aggr_break_handler;
1226         } else
1227                 list_add_rcu(&p->list, &ap->list);
1228         if (p->post_handler && !ap->post_handler)
1229                 ap->post_handler = aggr_post_handler;
1230 
1231         return 0;
1232 }
1233 
1234 /*
1235  * Fill in the required fields of the "manager kprobe". Replace the
1236  * earlier kprobe in the hlist with the manager kprobe
1237  */
1238 static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
1239 {
1240         /* Copy p's insn slot to ap */
1241         copy_kprobe(p, ap);
1242         flush_insn_slot(ap);
1243         ap->addr = p->addr;
1244         ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED;
1245         ap->pre_handler = aggr_pre_handler;
1246         ap->fault_handler = aggr_fault_handler;
1247         /* We don't care the kprobe which has gone. */
1248         if (p->post_handler && !kprobe_gone(p))
1249                 ap->post_handler = aggr_post_handler;
1250         if (p->break_handler && !kprobe_gone(p))
1251                 ap->break_handler = aggr_break_handler;
1252 
1253         INIT_LIST_HEAD(&ap->list);
1254         INIT_HLIST_NODE(&ap->hlist);
1255 
1256         list_add_rcu(&p->list, &ap->list);
1257         hlist_replace_rcu(&p->hlist, &ap->hlist);
1258 }
1259 
1260 /*
1261  * This is the second or subsequent kprobe at the address - handle
1262  * the intricacies
1263  */
1264 static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p)
1265 {
1266         int ret = 0;
1267         struct kprobe *ap = orig_p;
1268 
1269         /* For preparing optimization, jump_label_text_reserved() is called */
1270         jump_label_lock();
1271         /*
1272          * Get online CPUs to avoid text_mutex deadlock.with stop machine,
1273          * which is invoked by unoptimize_kprobe() in add_new_kprobe()
1274          */
1275         get_online_cpus();
1276         mutex_lock(&text_mutex);
1277 
1278         if (!kprobe_aggrprobe(orig_p)) {
1279                 /* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */
1280                 ap = alloc_aggr_kprobe(orig_p);
1281                 if (!ap) {
1282                         ret = -ENOMEM;
1283                         goto out;
1284                 }
1285                 init_aggr_kprobe(ap, orig_p);
1286         } else if (kprobe_unused(ap)) {
1287                 /* This probe is going to die. Rescue it */
1288                 ret = reuse_unused_kprobe(ap);
1289                 if (ret)
1290                         goto out;
1291         }
1292 
1293         if (kprobe_gone(ap)) {
1294                 /*
1295                  * Attempting to insert new probe at the same location that
1296                  * had a probe in the module vaddr area which already
1297                  * freed. So, the instruction slot has already been
1298                  * released. We need a new slot for the new probe.
1299                  */
1300                 ret = arch_prepare_kprobe(ap);
1301                 if (ret)
1302                         /*
1303                          * Even if fail to allocate new slot, don't need to
1304                          * free aggr_probe. It will be used next time, or
1305                          * freed by unregister_kprobe.
1306                          */
1307                         goto out;
1308 
1309                 /* Prepare optimized instructions if possible. */
1310                 prepare_optimized_kprobe(ap);
1311 
1312                 /*
1313                  * Clear gone flag to prevent allocating new slot again, and
1314                  * set disabled flag because it is not armed yet.
1315                  */
1316                 ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
1317                             | KPROBE_FLAG_DISABLED;
1318         }
1319 
1320         /* Copy ap's insn slot to p */
1321         copy_kprobe(ap, p);
1322         ret = add_new_kprobe(ap, p);
1323 
1324 out:
1325         mutex_unlock(&text_mutex);
1326         put_online_cpus();
1327         jump_label_unlock();
1328 
1329         if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) {
1330                 ap->flags &= ~KPROBE_FLAG_DISABLED;
1331                 if (!kprobes_all_disarmed)
1332                         /* Arm the breakpoint again. */
1333                         arm_kprobe(ap);
1334         }
1335         return ret;
1336 }
1337 
1338 bool __weak arch_within_kprobe_blacklist(unsigned long addr)
1339 {
1340         /* The __kprobes marked functions and entry code must not be probed */
1341         return addr >= (unsigned long)__kprobes_text_start &&
1342                addr < (unsigned long)__kprobes_text_end;
1343 }
1344 
1345 static bool within_kprobe_blacklist(unsigned long addr)
1346 {
1347         struct kprobe_blacklist_entry *ent;
1348 
1349         if (arch_within_kprobe_blacklist(addr))
1350                 return true;
1351         /*
1352          * If there exists a kprobe_blacklist, verify and
1353          * fail any probe registration in the prohibited area
1354          */
1355         list_for_each_entry(ent, &kprobe_blacklist, list) {
1356                 if (addr >= ent->start_addr && addr < ent->end_addr)
1357                         return true;
1358         }
1359 
1360         return false;
1361 }
1362 
1363 /*
1364  * If we have a symbol_name argument, look it up and add the offset field
1365  * to it. This way, we can specify a relative address to a symbol.
1366  * This returns encoded errors if it fails to look up symbol or invalid
1367  * combination of parameters.
1368  */
1369 static kprobe_opcode_t *kprobe_addr(struct kprobe *p)
1370 {
1371         kprobe_opcode_t *addr = p->addr;
1372 
1373         if ((p->symbol_name && p->addr) ||
1374             (!p->symbol_name && !p->addr))
1375                 goto invalid;
1376 
1377         if (p->symbol_name) {
1378                 kprobe_lookup_name(p->symbol_name, addr);
1379                 if (!addr)
1380                         return ERR_PTR(-ENOENT);
1381         }
1382 
1383         addr = (kprobe_opcode_t *)(((char *)addr) + p->offset);
1384         if (addr)
1385                 return addr;
1386 
1387 invalid:
1388         return ERR_PTR(-EINVAL);
1389 }
1390 
1391 /* Check passed kprobe is valid and return kprobe in kprobe_table. */
1392 static struct kprobe *__get_valid_kprobe(struct kprobe *p)
1393 {
1394         struct kprobe *ap, *list_p;
1395 
1396         ap = get_kprobe(p->addr);
1397         if (unlikely(!ap))
1398                 return NULL;
1399 
1400         if (p != ap) {
1401                 list_for_each_entry_rcu(list_p, &ap->list, list)
1402                         if (list_p == p)
1403                         /* kprobe p is a valid probe */
1404                                 goto valid;
1405                 return NULL;
1406         }
1407 valid:
1408         return ap;
1409 }
1410 
1411 /* Return error if the kprobe is being re-registered */
1412 static inline int check_kprobe_rereg(struct kprobe *p)
1413 {
1414         int ret = 0;
1415 
1416         mutex_lock(&kprobe_mutex);
1417         if (__get_valid_kprobe(p))
1418                 ret = -EINVAL;
1419         mutex_unlock(&kprobe_mutex);
1420 
1421         return ret;
1422 }
1423 
1424 static int check_kprobe_address_safe(struct kprobe *p,
1425                                      struct module **probed_mod)
1426 {
1427         int ret = 0;
1428         unsigned long ftrace_addr;
1429 
1430         /*
1431          * If the address is located on a ftrace nop, set the
1432          * breakpoint to the following instruction.
1433          */
1434         ftrace_addr = ftrace_location((unsigned long)p->addr);
1435         if (ftrace_addr) {
1436 #ifdef CONFIG_KPROBES_ON_FTRACE
1437                 /* Given address is not on the instruction boundary */
1438                 if ((unsigned long)p->addr != ftrace_addr)
1439                         return -EILSEQ;
1440                 p->flags |= KPROBE_FLAG_FTRACE;
1441 #else   /* !CONFIG_KPROBES_ON_FTRACE */
1442                 return -EINVAL;
1443 #endif
1444         }
1445 
1446         jump_label_lock();
1447         preempt_disable();
1448 
1449         /* Ensure it is not in reserved area nor out of text */
1450         if (!kernel_text_address((unsigned long) p->addr) ||
1451             within_kprobe_blacklist((unsigned long) p->addr) ||
1452             jump_label_text_reserved(p->addr, p->addr)) {
1453                 ret = -EINVAL;
1454                 goto out;
1455         }
1456 
1457         /* Check if are we probing a module */
1458         *probed_mod = __module_text_address((unsigned long) p->addr);
1459         if (*probed_mod) {
1460                 /*
1461                  * We must hold a refcount of the probed module while updating
1462                  * its code to prohibit unexpected unloading.
1463                  */
1464                 if (unlikely(!try_module_get(*probed_mod))) {
1465                         ret = -ENOENT;
1466                         goto out;
1467                 }
1468 
1469                 /*
1470                  * If the module freed .init.text, we couldn't insert
1471                  * kprobes in there.
1472                  */
1473                 if (within_module_init((unsigned long)p->addr, *probed_mod) &&
1474                     (*probed_mod)->state != MODULE_STATE_COMING) {
1475                         module_put(*probed_mod);
1476                         *probed_mod = NULL;
1477                         ret = -ENOENT;
1478                 }
1479         }
1480 out:
1481         preempt_enable();
1482         jump_label_unlock();
1483 
1484         return ret;
1485 }
1486 
1487 int register_kprobe(struct kprobe *p)
1488 {
1489         int ret;
1490         struct kprobe *old_p;
1491         struct module *probed_mod;
1492         kprobe_opcode_t *addr;
1493 
1494         /* Adjust probe address from symbol */
1495         addr = kprobe_addr(p);
1496         if (IS_ERR(addr))
1497                 return PTR_ERR(addr);
1498         p->addr = addr;
1499 
1500         ret = check_kprobe_rereg(p);
1501         if (ret)
1502                 return ret;
1503 
1504         /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
1505         p->flags &= KPROBE_FLAG_DISABLED;
1506         p->nmissed = 0;
1507         INIT_LIST_HEAD(&p->list);
1508 
1509         ret = check_kprobe_address_safe(p, &probed_mod);
1510         if (ret)
1511                 return ret;
1512 
1513         mutex_lock(&kprobe_mutex);
1514 
1515         old_p = get_kprobe(p->addr);
1516         if (old_p) {
1517                 /* Since this may unoptimize old_p, locking text_mutex. */
1518                 ret = register_aggr_kprobe(old_p, p);
1519                 goto out;
1520         }
1521 
1522         mutex_lock(&text_mutex);        /* Avoiding text modification */
1523         ret = prepare_kprobe(p);
1524         mutex_unlock(&text_mutex);
1525         if (ret)
1526                 goto out;
1527 
1528         INIT_HLIST_NODE(&p->hlist);
1529         hlist_add_head_rcu(&p->hlist,
1530                        &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
1531 
1532         if (!kprobes_all_disarmed && !kprobe_disabled(p))
1533                 arm_kprobe(p);
1534 
1535         /* Try to optimize kprobe */
1536         try_to_optimize_kprobe(p);
1537 
1538 out:
1539         mutex_unlock(&kprobe_mutex);
1540 
1541         if (probed_mod)
1542                 module_put(probed_mod);
1543 
1544         return ret;
1545 }
1546 EXPORT_SYMBOL_GPL(register_kprobe);
1547 
1548 /* Check if all probes on the aggrprobe are disabled */
1549 static int aggr_kprobe_disabled(struct kprobe *ap)
1550 {
1551         struct kprobe *kp;
1552 
1553         list_for_each_entry_rcu(kp, &ap->list, list)
1554                 if (!kprobe_disabled(kp))
1555                         /*
1556                          * There is an active probe on the list.
1557                          * We can't disable this ap.
1558                          */
1559                         return 0;
1560 
1561         return 1;
1562 }
1563 
1564 /* Disable one kprobe: Make sure called under kprobe_mutex is locked */
1565 static struct kprobe *__disable_kprobe(struct kprobe *p)
1566 {
1567         struct kprobe *orig_p;
1568 
1569         /* Get an original kprobe for return */
1570         orig_p = __get_valid_kprobe(p);
1571         if (unlikely(orig_p == NULL))
1572                 return NULL;
1573 
1574         if (!kprobe_disabled(p)) {
1575                 /* Disable probe if it is a child probe */
1576                 if (p != orig_p)
1577                         p->flags |= KPROBE_FLAG_DISABLED;
1578 
1579                 /* Try to disarm and disable this/parent probe */
1580                 if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
1581                         disarm_kprobe(orig_p, true);
1582                         orig_p->flags |= KPROBE_FLAG_DISABLED;
1583                 }
1584         }
1585 
1586         return orig_p;
1587 }
1588 
1589 /*
1590  * Unregister a kprobe without a scheduler synchronization.
1591  */
1592 static int __unregister_kprobe_top(struct kprobe *p)
1593 {
1594         struct kprobe *ap, *list_p;
1595 
1596         /* Disable kprobe. This will disarm it if needed. */
1597         ap = __disable_kprobe(p);
1598         if (ap == NULL)
1599                 return -EINVAL;
1600 
1601         if (ap == p)
1602                 /*
1603                  * This probe is an independent(and non-optimized) kprobe
1604                  * (not an aggrprobe). Remove from the hash list.
1605                  */
1606                 goto disarmed;
1607 
1608         /* Following process expects this probe is an aggrprobe */
1609         WARN_ON(!kprobe_aggrprobe(ap));
1610 
1611         if (list_is_singular(&ap->list) && kprobe_disarmed(ap))
1612                 /*
1613                  * !disarmed could be happen if the probe is under delayed
1614                  * unoptimizing.
1615                  */
1616                 goto disarmed;
1617         else {
1618                 /* If disabling probe has special handlers, update aggrprobe */
1619                 if (p->break_handler && !kprobe_gone(p))
1620                         ap->break_handler = NULL;
1621                 if (p->post_handler && !kprobe_gone(p)) {
1622                         list_for_each_entry_rcu(list_p, &ap->list, list) {
1623                                 if ((list_p != p) && (list_p->post_handler))
1624                                         goto noclean;
1625                         }
1626                         ap->post_handler = NULL;
1627                 }
1628 noclean:
1629                 /*
1630                  * Remove from the aggrprobe: this path will do nothing in
1631                  * __unregister_kprobe_bottom().
1632                  */
1633                 list_del_rcu(&p->list);
1634                 if (!kprobe_disabled(ap) && !kprobes_all_disarmed)
1635                         /*
1636                          * Try to optimize this probe again, because post
1637                          * handler may have been changed.
1638                          */
1639                         optimize_kprobe(ap);
1640         }
1641         return 0;
1642 
1643 disarmed:
1644         BUG_ON(!kprobe_disarmed(ap));
1645         hlist_del_rcu(&ap->hlist);
1646         return 0;
1647 }
1648 
1649 static void __unregister_kprobe_bottom(struct kprobe *p)
1650 {
1651         struct kprobe *ap;
1652 
1653         if (list_empty(&p->list))
1654                 /* This is an independent kprobe */
1655                 arch_remove_kprobe(p);
1656         else if (list_is_singular(&p->list)) {
1657                 /* This is the last child of an aggrprobe */
1658                 ap = list_entry(p->list.next, struct kprobe, list);
1659                 list_del(&p->list);
1660                 free_aggr_kprobe(ap);
1661         }
1662         /* Otherwise, do nothing. */
1663 }
1664 
1665 int register_kprobes(struct kprobe **kps, int num)
1666 {
1667         int i, ret = 0;
1668 
1669         if (num <= 0)
1670                 return -EINVAL;
1671         for (i = 0; i < num; i++) {
1672                 ret = register_kprobe(kps[i]);
1673                 if (ret < 0) {
1674                         if (i > 0)
1675                                 unregister_kprobes(kps, i);
1676                         break;
1677                 }
1678         }
1679         return ret;
1680 }
1681 EXPORT_SYMBOL_GPL(register_kprobes);
1682 
1683 void unregister_kprobe(struct kprobe *p)
1684 {
1685         unregister_kprobes(&p, 1);
1686 }
1687 EXPORT_SYMBOL_GPL(unregister_kprobe);
1688 
1689 void unregister_kprobes(struct kprobe **kps, int num)
1690 {
1691         int i;
1692 
1693         if (num <= 0)
1694                 return;
1695         mutex_lock(&kprobe_mutex);
1696         for (i = 0; i < num; i++)
1697                 if (__unregister_kprobe_top(kps[i]) < 0)
1698                         kps[i]->addr = NULL;
1699         mutex_unlock(&kprobe_mutex);
1700 
1701         synchronize_sched();
1702         for (i = 0; i < num; i++)
1703                 if (kps[i]->addr)
1704                         __unregister_kprobe_bottom(kps[i]);
1705 }
1706 EXPORT_SYMBOL_GPL(unregister_kprobes);
1707 
1708 static struct notifier_block kprobe_exceptions_nb = {
1709         .notifier_call = kprobe_exceptions_notify,
1710         .priority = 0x7fffffff /* we need to be notified first */
1711 };
1712 
1713 unsigned long __weak arch_deref_entry_point(void *entry)
1714 {
1715         return (unsigned long)entry;
1716 }
1717 
1718 int register_jprobes(struct jprobe **jps, int num)
1719 {
1720         struct jprobe *jp;
1721         int ret = 0, i;
1722 
1723         if (num <= 0)
1724                 return -EINVAL;
1725         for (i = 0; i < num; i++) {
1726                 unsigned long addr, offset;
1727                 jp = jps[i];
1728                 addr = arch_deref_entry_point(jp->entry);
1729 
1730                 /* Verify probepoint is a function entry point */
1731                 if (kallsyms_lookup_size_offset(addr, NULL, &offset) &&
1732                     offset == 0) {
1733                         jp->kp.pre_handler = setjmp_pre_handler;
1734                         jp->kp.break_handler = longjmp_break_handler;
1735                         ret = register_kprobe(&jp->kp);
1736                 } else
1737                         ret = -EINVAL;
1738 
1739                 if (ret < 0) {
1740                         if (i > 0)
1741                                 unregister_jprobes(jps, i);
1742                         break;
1743                 }
1744         }
1745         return ret;
1746 }
1747 EXPORT_SYMBOL_GPL(register_jprobes);
1748 
1749 int register_jprobe(struct jprobe *jp)
1750 {
1751         return register_jprobes(&jp, 1);
1752 }
1753 EXPORT_SYMBOL_GPL(register_jprobe);
1754 
1755 void unregister_jprobe(struct jprobe *jp)
1756 {
1757         unregister_jprobes(&jp, 1);
1758 }
1759 EXPORT_SYMBOL_GPL(unregister_jprobe);
1760 
1761 void unregister_jprobes(struct jprobe **jps, int num)
1762 {
1763         int i;
1764 
1765         if (num <= 0)
1766                 return;
1767         mutex_lock(&kprobe_mutex);
1768         for (i = 0; i < num; i++)
1769                 if (__unregister_kprobe_top(&jps[i]->kp) < 0)
1770                         jps[i]->kp.addr = NULL;
1771         mutex_unlock(&kprobe_mutex);
1772 
1773         synchronize_sched();
1774         for (i = 0; i < num; i++) {
1775                 if (jps[i]->kp.addr)
1776                         __unregister_kprobe_bottom(&jps[i]->kp);
1777         }
1778 }
1779 EXPORT_SYMBOL_GPL(unregister_jprobes);
1780 
1781 #ifdef CONFIG_KRETPROBES
1782 /*
1783  * This kprobe pre_handler is registered with every kretprobe. When probe
1784  * hits it will set up the return probe.
1785  */
1786 static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
1787 {
1788         struct kretprobe *rp = container_of(p, struct kretprobe, kp);
1789         unsigned long hash, flags = 0;
1790         struct kretprobe_instance *ri;
1791 
1792         /*
1793          * To avoid deadlocks, prohibit return probing in NMI contexts,
1794          * just skip the probe and increase the (inexact) 'nmissed'
1795          * statistical counter, so that the user is informed that
1796          * something happened:
1797          */
1798         if (unlikely(in_nmi())) {
1799                 rp->nmissed++;
1800                 return 0;
1801         }
1802 
1803         /* TODO: consider to only swap the RA after the last pre_handler fired */
1804         hash = hash_ptr(current, KPROBE_HASH_BITS);
1805         raw_spin_lock_irqsave(&rp->lock, flags);
1806         if (!hlist_empty(&rp->free_instances)) {
1807                 ri = hlist_entry(rp->free_instances.first,
1808                                 struct kretprobe_instance, hlist);
1809                 hlist_del(&ri->hlist);
1810                 raw_spin_unlock_irqrestore(&rp->lock, flags);
1811 
1812                 ri->rp = rp;
1813                 ri->task = current;
1814 
1815                 if (rp->entry_handler && rp->entry_handler(ri, regs)) {
1816                         raw_spin_lock_irqsave(&rp->lock, flags);
1817                         hlist_add_head(&ri->hlist, &rp->free_instances);
1818                         raw_spin_unlock_irqrestore(&rp->lock, flags);
1819                         return 0;
1820                 }
1821 
1822                 arch_prepare_kretprobe(ri, regs);
1823 
1824                 /* XXX(hch): why is there no hlist_move_head? */
1825                 INIT_HLIST_NODE(&ri->hlist);
1826                 kretprobe_table_lock(hash, &flags);
1827                 hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
1828                 kretprobe_table_unlock(hash, &flags);
1829         } else {
1830                 rp->nmissed++;
1831                 raw_spin_unlock_irqrestore(&rp->lock, flags);
1832         }
1833         return 0;
1834 }
1835 NOKPROBE_SYMBOL(pre_handler_kretprobe);
1836 
1837 int register_kretprobe(struct kretprobe *rp)
1838 {
1839         int ret = 0;
1840         struct kretprobe_instance *inst;
1841         int i;
1842         void *addr;
1843 
1844         if (kretprobe_blacklist_size) {
1845                 addr = kprobe_addr(&rp->kp);
1846                 if (IS_ERR(addr))
1847                         return PTR_ERR(addr);
1848 
1849                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1850                         if (kretprobe_blacklist[i].addr == addr)
1851                                 return -EINVAL;
1852                 }
1853         }
1854 
1855         rp->kp.pre_handler = pre_handler_kretprobe;
1856         rp->kp.post_handler = NULL;
1857         rp->kp.fault_handler = NULL;
1858         rp->kp.break_handler = NULL;
1859 
1860         /* Pre-allocate memory for max kretprobe instances */
1861         if (rp->maxactive <= 0) {
1862 #ifdef CONFIG_PREEMPT
1863                 rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
1864 #else
1865                 rp->maxactive = num_possible_cpus();
1866 #endif
1867         }
1868         raw_spin_lock_init(&rp->lock);
1869         INIT_HLIST_HEAD(&rp->free_instances);
1870         for (i = 0; i < rp->maxactive; i++) {
1871                 inst = kmalloc(sizeof(struct kretprobe_instance) +
1872                                rp->data_size, GFP_KERNEL);
1873                 if (inst == NULL) {
1874                         free_rp_inst(rp);
1875                         return -ENOMEM;
1876                 }
1877                 INIT_HLIST_NODE(&inst->hlist);
1878                 hlist_add_head(&inst->hlist, &rp->free_instances);
1879         }
1880 
1881         rp->nmissed = 0;
1882         /* Establish function entry probe point */
1883         ret = register_kprobe(&rp->kp);
1884         if (ret != 0)
1885                 free_rp_inst(rp);
1886         return ret;
1887 }
1888 EXPORT_SYMBOL_GPL(register_kretprobe);
1889 
1890 int register_kretprobes(struct kretprobe **rps, int num)
1891 {
1892         int ret = 0, i;
1893 
1894         if (num <= 0)
1895                 return -EINVAL;
1896         for (i = 0; i < num; i++) {
1897                 ret = register_kretprobe(rps[i]);
1898                 if (ret < 0) {
1899                         if (i > 0)
1900                                 unregister_kretprobes(rps, i);
1901                         break;
1902                 }
1903         }
1904         return ret;
1905 }
1906 EXPORT_SYMBOL_GPL(register_kretprobes);
1907 
1908 void unregister_kretprobe(struct kretprobe *rp)
1909 {
1910         unregister_kretprobes(&rp, 1);
1911 }
1912 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1913 
1914 void unregister_kretprobes(struct kretprobe **rps, int num)
1915 {
1916         int i;
1917 
1918         if (num <= 0)
1919                 return;
1920         mutex_lock(&kprobe_mutex);
1921         for (i = 0; i < num; i++)
1922                 if (__unregister_kprobe_top(&rps[i]->kp) < 0)
1923                         rps[i]->kp.addr = NULL;
1924         mutex_unlock(&kprobe_mutex);
1925 
1926         synchronize_sched();
1927         for (i = 0; i < num; i++) {
1928                 if (rps[i]->kp.addr) {
1929                         __unregister_kprobe_bottom(&rps[i]->kp);
1930                         cleanup_rp_inst(rps[i]);
1931                 }
1932         }
1933 }
1934 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1935 
1936 #else /* CONFIG_KRETPROBES */
1937 int register_kretprobe(struct kretprobe *rp)
1938 {
1939         return -ENOSYS;
1940 }
1941 EXPORT_SYMBOL_GPL(register_kretprobe);
1942 
1943 int register_kretprobes(struct kretprobe **rps, int num)
1944 {
1945         return -ENOSYS;
1946 }
1947 EXPORT_SYMBOL_GPL(register_kretprobes);
1948 
1949 void unregister_kretprobe(struct kretprobe *rp)
1950 {
1951 }
1952 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1953 
1954 void unregister_kretprobes(struct kretprobe **rps, int num)
1955 {
1956 }
1957 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1958 
1959 static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
1960 {
1961         return 0;
1962 }
1963 NOKPROBE_SYMBOL(pre_handler_kretprobe);
1964 
1965 #endif /* CONFIG_KRETPROBES */
1966 
1967 /* Set the kprobe gone and remove its instruction buffer. */
1968 static void kill_kprobe(struct kprobe *p)
1969 {
1970         struct kprobe *kp;
1971 
1972         p->flags |= KPROBE_FLAG_GONE;
1973         if (kprobe_aggrprobe(p)) {
1974                 /*
1975                  * If this is an aggr_kprobe, we have to list all the
1976                  * chained probes and mark them GONE.
1977                  */
1978                 list_for_each_entry_rcu(kp, &p->list, list)
1979                         kp->flags |= KPROBE_FLAG_GONE;
1980                 p->post_handler = NULL;
1981                 p->break_handler = NULL;
1982                 kill_optimized_kprobe(p);
1983         }
1984         /*
1985          * Here, we can remove insn_slot safely, because no thread calls
1986          * the original probed function (which will be freed soon) any more.
1987          */
1988         arch_remove_kprobe(p);
1989 }
1990 
1991 /* Disable one kprobe */
1992 int disable_kprobe(struct kprobe *kp)
1993 {
1994         int ret = 0;
1995 
1996         mutex_lock(&kprobe_mutex);
1997 
1998         /* Disable this kprobe */
1999         if (__disable_kprobe(kp) == NULL)
2000                 ret = -EINVAL;
2001 
2002         mutex_unlock(&kprobe_mutex);
2003         return ret;
2004 }
2005 EXPORT_SYMBOL_GPL(disable_kprobe);
2006 
2007 /* Enable one kprobe */
2008 int enable_kprobe(struct kprobe *kp)
2009 {
2010         int ret = 0;
2011         struct kprobe *p;
2012 
2013         mutex_lock(&kprobe_mutex);
2014 
2015         /* Check whether specified probe is valid. */
2016         p = __get_valid_kprobe(kp);
2017         if (unlikely(p == NULL)) {
2018                 ret = -EINVAL;
2019                 goto out;
2020         }
2021 
2022         if (kprobe_gone(kp)) {
2023                 /* This kprobe has gone, we couldn't enable it. */
2024                 ret = -EINVAL;
2025                 goto out;
2026         }
2027 
2028         if (p != kp)
2029                 kp->flags &= ~KPROBE_FLAG_DISABLED;
2030 
2031         if (!kprobes_all_disarmed && kprobe_disabled(p)) {
2032                 p->flags &= ~KPROBE_FLAG_DISABLED;
2033                 arm_kprobe(p);
2034         }
2035 out:
2036         mutex_unlock(&kprobe_mutex);
2037         return ret;
2038 }
2039 EXPORT_SYMBOL_GPL(enable_kprobe);
2040 
2041 void dump_kprobe(struct kprobe *kp)
2042 {
2043         printk(KERN_WARNING "Dumping kprobe:\n");
2044         printk(KERN_WARNING "Name: %s\nAddress: %p\nOffset: %x\n",
2045                kp->symbol_name, kp->addr, kp->offset);
2046 }
2047 NOKPROBE_SYMBOL(dump_kprobe);
2048 
2049 /*
2050  * Lookup and populate the kprobe_blacklist.
2051  *
2052  * Unlike the kretprobe blacklist, we'll need to determine
2053  * the range of addresses that belong to the said functions,
2054  * since a kprobe need not necessarily be at the beginning
2055  * of a function.
2056  */
2057 static int __init populate_kprobe_blacklist(unsigned long *start,
2058                                              unsigned long *end)
2059 {
2060         unsigned long *iter;
2061         struct kprobe_blacklist_entry *ent;
2062         unsigned long entry, offset = 0, size = 0;
2063 
2064         for (iter = start; iter < end; iter++) {
2065                 entry = arch_deref_entry_point((void *)*iter);
2066 
2067                 if (!kernel_text_address(entry) ||
2068                     !kallsyms_lookup_size_offset(entry, &size, &offset)) {
2069                         pr_err("Failed to find blacklist at %p\n",
2070                                 (void *)entry);
2071                         continue;
2072                 }
2073 
2074                 ent = kmalloc(sizeof(*ent), GFP_KERNEL);
2075                 if (!ent)
2076                         return -ENOMEM;
2077                 ent->start_addr = entry;
2078                 ent->end_addr = entry + size;
2079                 INIT_LIST_HEAD(&ent->list);
2080                 list_add_tail(&ent->list, &kprobe_blacklist);
2081         }
2082         return 0;
2083 }
2084 
2085 /* Module notifier call back, checking kprobes on the module */
2086 static int kprobes_module_callback(struct notifier_block *nb,
2087                                    unsigned long val, void *data)
2088 {
2089         struct module *mod = data;
2090         struct hlist_head *head;
2091         struct kprobe *p;
2092         unsigned int i;
2093         int checkcore = (val == MODULE_STATE_GOING);
2094 
2095         if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
2096                 return NOTIFY_DONE;
2097 
2098         /*
2099          * When MODULE_STATE_GOING was notified, both of module .text and
2100          * .init.text sections would be freed. When MODULE_STATE_LIVE was
2101          * notified, only .init.text section would be freed. We need to
2102          * disable kprobes which have been inserted in the sections.
2103          */
2104         mutex_lock(&kprobe_mutex);
2105         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2106                 head = &kprobe_table[i];
2107                 hlist_for_each_entry_rcu(p, head, hlist)
2108                         if (within_module_init((unsigned long)p->addr, mod) ||
2109                             (checkcore &&
2110                              within_module_core((unsigned long)p->addr, mod))) {
2111                                 /*
2112                                  * The vaddr this probe is installed will soon
2113                                  * be vfreed buy not synced to disk. Hence,
2114                                  * disarming the breakpoint isn't needed.
2115                                  */
2116                                 kill_kprobe(p);
2117                         }
2118         }
2119         mutex_unlock(&kprobe_mutex);
2120         return NOTIFY_DONE;
2121 }
2122 
2123 static struct notifier_block kprobe_module_nb = {
2124         .notifier_call = kprobes_module_callback,
2125         .priority = 0
2126 };
2127 
2128 /* Markers of _kprobe_blacklist section */
2129 extern unsigned long __start_kprobe_blacklist[];
2130 extern unsigned long __stop_kprobe_blacklist[];
2131 
2132 static int __init init_kprobes(void)
2133 {
2134         int i, err = 0;
2135 
2136         /* FIXME allocate the probe table, currently defined statically */
2137         /* initialize all list heads */
2138         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2139                 INIT_HLIST_HEAD(&kprobe_table[i]);
2140                 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
2141                 raw_spin_lock_init(&(kretprobe_table_locks[i].lock));
2142         }
2143 
2144         err = populate_kprobe_blacklist(__start_kprobe_blacklist,
2145                                         __stop_kprobe_blacklist);
2146         if (err) {
2147                 pr_err("kprobes: failed to populate blacklist: %d\n", err);
2148                 pr_err("Please take care of using kprobes.\n");
2149         }
2150 
2151         if (kretprobe_blacklist_size) {
2152                 /* lookup the function address from its name */
2153                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
2154                         kprobe_lookup_name(kretprobe_blacklist[i].name,
2155                                            kretprobe_blacklist[i].addr);
2156                         if (!kretprobe_blacklist[i].addr)
2157                                 printk("kretprobe: lookup failed: %s\n",
2158                                        kretprobe_blacklist[i].name);
2159                 }
2160         }
2161 
2162 #if defined(CONFIG_OPTPROBES)
2163 #if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
2164         /* Init kprobe_optinsn_slots */
2165         kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
2166 #endif
2167         /* By default, kprobes can be optimized */
2168         kprobes_allow_optimization = true;
2169 #endif
2170 
2171         /* By default, kprobes are armed */
2172         kprobes_all_disarmed = false;
2173 
2174         err = arch_init_kprobes();
2175         if (!err)
2176                 err = register_die_notifier(&kprobe_exceptions_nb);
2177         if (!err)
2178                 err = register_module_notifier(&kprobe_module_nb);
2179 
2180         kprobes_initialized = (err == 0);
2181 
2182         if (!err)
2183                 init_test_probes();
2184         return err;
2185 }
2186 
2187 #ifdef CONFIG_DEBUG_FS
2188 static void report_probe(struct seq_file *pi, struct kprobe *p,
2189                 const char *sym, int offset, char *modname, struct kprobe *pp)
2190 {
2191         char *kprobe_type;
2192 
2193         if (p->pre_handler == pre_handler_kretprobe)
2194                 kprobe_type = "r";
2195         else if (p->pre_handler == setjmp_pre_handler)
2196                 kprobe_type = "j";
2197         else
2198                 kprobe_type = "k";
2199 
2200         if (sym)
2201                 seq_printf(pi, "%p  %s  %s+0x%x  %s ",
2202                         p->addr, kprobe_type, sym, offset,
2203                         (modname ? modname : " "));
2204         else
2205                 seq_printf(pi, "%p  %s  %p ",
2206                         p->addr, kprobe_type, p->addr);
2207 
2208         if (!pp)
2209                 pp = p;
2210         seq_printf(pi, "%s%s%s%s\n",
2211                 (kprobe_gone(p) ? "[GONE]" : ""),
2212                 ((kprobe_disabled(p) && !kprobe_gone(p)) ?  "[DISABLED]" : ""),
2213                 (kprobe_optimized(pp) ? "[OPTIMIZED]" : ""),
2214                 (kprobe_ftrace(pp) ? "[FTRACE]" : ""));
2215 }
2216 
2217 static void *kprobe_seq_start(struct seq_file *f, loff_t *pos)
2218 {
2219         return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
2220 }
2221 
2222 static void *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
2223 {
2224         (*pos)++;
2225         if (*pos >= KPROBE_TABLE_SIZE)
2226                 return NULL;
2227         return pos;
2228 }
2229 
2230 static void kprobe_seq_stop(struct seq_file *f, void *v)
2231 {
2232         /* Nothing to do */
2233 }
2234 
2235 static int show_kprobe_addr(struct seq_file *pi, void *v)
2236 {
2237         struct hlist_head *head;
2238         struct kprobe *p, *kp;
2239         const char *sym = NULL;
2240         unsigned int i = *(loff_t *) v;
2241         unsigned long offset = 0;
2242         char *modname, namebuf[KSYM_NAME_LEN];
2243 
2244         head = &kprobe_table[i];
2245         preempt_disable();
2246         hlist_for_each_entry_rcu(p, head, hlist) {
2247                 sym = kallsyms_lookup((unsigned long)p->addr, NULL,
2248                                         &offset, &modname, namebuf);
2249                 if (kprobe_aggrprobe(p)) {
2250                         list_for_each_entry_rcu(kp, &p->list, list)
2251                                 report_probe(pi, kp, sym, offset, modname, p);
2252                 } else
2253                         report_probe(pi, p, sym, offset, modname, NULL);
2254         }
2255         preempt_enable();
2256         return 0;
2257 }
2258 
2259 static const struct seq_operations kprobes_seq_ops = {
2260         .start = kprobe_seq_start,
2261         .next  = kprobe_seq_next,
2262         .stop  = kprobe_seq_stop,
2263         .show  = show_kprobe_addr
2264 };
2265 
2266 static int kprobes_open(struct inode *inode, struct file *filp)
2267 {
2268         return seq_open(filp, &kprobes_seq_ops);
2269 }
2270 
2271 static const struct file_operations debugfs_kprobes_operations = {
2272         .open           = kprobes_open,
2273         .read           = seq_read,
2274         .llseek         = seq_lseek,
2275         .release        = seq_release,
2276 };
2277 
2278 /* kprobes/blacklist -- shows which functions can not be probed */
2279 static void *kprobe_blacklist_seq_start(struct seq_file *m, loff_t *pos)
2280 {
2281         return seq_list_start(&kprobe_blacklist, *pos);
2282 }
2283 
2284 static void *kprobe_blacklist_seq_next(struct seq_file *m, void *v, loff_t *pos)
2285 {
2286         return seq_list_next(v, &kprobe_blacklist, pos);
2287 }
2288 
2289 static int kprobe_blacklist_seq_show(struct seq_file *m, void *v)
2290 {
2291         struct kprobe_blacklist_entry *ent =
2292                 list_entry(v, struct kprobe_blacklist_entry, list);
2293 
2294         seq_printf(m, "0x%p-0x%p\t%ps\n", (void *)ent->start_addr,
2295                    (void *)ent->end_addr, (void *)ent->start_addr);
2296         return 0;
2297 }
2298 
2299 static const struct seq_operations kprobe_blacklist_seq_ops = {
2300         .start = kprobe_blacklist_seq_start,
2301         .next  = kprobe_blacklist_seq_next,
2302         .stop  = kprobe_seq_stop,       /* Reuse void function */
2303         .show  = kprobe_blacklist_seq_show,
2304 };
2305 
2306 static int kprobe_blacklist_open(struct inode *inode, struct file *filp)
2307 {
2308         return seq_open(filp, &kprobe_blacklist_seq_ops);
2309 }
2310 
2311 static const struct file_operations debugfs_kprobe_blacklist_ops = {
2312         .open           = kprobe_blacklist_open,
2313         .read           = seq_read,
2314         .llseek         = seq_lseek,
2315         .release        = seq_release,
2316 };
2317 
2318 static void arm_all_kprobes(void)
2319 {
2320         struct hlist_head *head;
2321         struct kprobe *p;
2322         unsigned int i;
2323 
2324         mutex_lock(&kprobe_mutex);
2325 
2326         /* If kprobes are armed, just return */
2327         if (!kprobes_all_disarmed)
2328                 goto already_enabled;
2329 
2330         /* Arming kprobes doesn't optimize kprobe itself */
2331         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2332                 head = &kprobe_table[i];
2333                 hlist_for_each_entry_rcu(p, head, hlist)
2334                         if (!kprobe_disabled(p))
2335                                 arm_kprobe(p);
2336         }
2337 
2338         kprobes_all_disarmed = false;
2339         printk(KERN_INFO "Kprobes globally enabled\n");
2340 
2341 already_enabled:
2342         mutex_unlock(&kprobe_mutex);
2343         return;
2344 }
2345 
2346 static void disarm_all_kprobes(void)
2347 {
2348         struct hlist_head *head;
2349         struct kprobe *p;
2350         unsigned int i;
2351 
2352         mutex_lock(&kprobe_mutex);
2353 
2354         /* If kprobes are already disarmed, just return */
2355         if (kprobes_all_disarmed) {
2356                 mutex_unlock(&kprobe_mutex);
2357                 return;
2358         }
2359 
2360         kprobes_all_disarmed = true;
2361         printk(KERN_INFO "Kprobes globally disabled\n");
2362 
2363         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2364                 head = &kprobe_table[i];
2365                 hlist_for_each_entry_rcu(p, head, hlist) {
2366                         if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
2367                                 disarm_kprobe(p, false);
2368                 }
2369         }
2370         mutex_unlock(&kprobe_mutex);
2371 
2372         /* Wait for disarming all kprobes by optimizer */
2373         wait_for_kprobe_optimizer();
2374 }
2375 
2376 /*
2377  * XXX: The debugfs bool file interface doesn't allow for callbacks
2378  * when the bool state is switched. We can reuse that facility when
2379  * available
2380  */
2381 static ssize_t read_enabled_file_bool(struct file *file,
2382                char __user *user_buf, size_t count, loff_t *ppos)
2383 {
2384         char buf[3];
2385 
2386         if (!kprobes_all_disarmed)
2387                 buf[0] = '1';
2388         else
2389                 buf[0] = '';
2390         buf[1] = '\n';
2391         buf[2] = 0x00;
2392         return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
2393 }
2394 
2395 static ssize_t write_enabled_file_bool(struct file *file,
2396                const char __user *user_buf, size_t count, loff_t *ppos)
2397 {
2398         char buf[32];
2399         size_t buf_size;
2400 
2401         buf_size = min(count, (sizeof(buf)-1));
2402         if (copy_from_user(buf, user_buf, buf_size))
2403                 return -EFAULT;
2404 
2405         buf[buf_size] = '\0';
2406         switch (buf[0]) {
2407         case 'y':
2408         case 'Y':
2409         case '1':
2410                 arm_all_kprobes();
2411                 break;
2412         case 'n':
2413         case 'N':
2414         case '':
2415                 disarm_all_kprobes();
2416                 break;
2417         default:
2418                 return -EINVAL;
2419         }
2420 
2421         return count;
2422 }
2423 
2424 static const struct file_operations fops_kp = {
2425         .read =         read_enabled_file_bool,
2426         .write =        write_enabled_file_bool,
2427         .llseek =       default_llseek,
2428 };
2429 
2430 static int __init debugfs_kprobe_init(void)
2431 {
2432         struct dentry *dir, *file;
2433         unsigned int value = 1;
2434 
2435         dir = debugfs_create_dir("kprobes", NULL);
2436         if (!dir)
2437                 return -ENOMEM;
2438 
2439         file = debugfs_create_file("list", 0400, dir, NULL,
2440                                 &debugfs_kprobes_operations);
2441         if (!file)
2442                 goto error;
2443 
2444         file = debugfs_create_file("enabled", 0600, dir,
2445                                         &value, &fops_kp);
2446         if (!file)
2447                 goto error;
2448 
2449         file = debugfs_create_file("blacklist", 0400, dir, NULL,
2450                                 &debugfs_kprobe_blacklist_ops);
2451         if (!file)
2452                 goto error;
2453 
2454         return 0;
2455 
2456 error:
2457         debugfs_remove(dir);
2458         return -ENOMEM;
2459 }
2460 
2461 late_initcall(debugfs_kprobe_init);
2462 #endif /* CONFIG_DEBUG_FS */
2463 
2464 module_init(init_kprobes);
2465 
2466 /* defined in arch/.../kernel/kprobes.c */
2467 EXPORT_SYMBOL_GPL(jprobe_return);
2468 

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