projects/linux·blob v4.11 · refs

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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 <[email protected]> Kernel
22 * Probes initial implementation (includes suggestions from
23 * Rusty Russell).
24 * 2004-Aug Updated by Prasanna S Panchamukhi <[email protected]> with
25 * hlists and exceptions notifier as suggested by Andi Kleen.
26 * 2004-July Suparna Bhattacharya <[email protected]> added jumper probes
27 * interface to access function arguments.
28 * 2004-Sep Prasanna S Panchamukhi <[email protected]> Changed Kprobes
29 * exceptions notifier to be first on the priority list.
30 * 2005-May Hien Nguyen <[email protected]>, Jim Keniston
31 * <[email protected]> and Prasanna S Panchamukhi
32 * <[email protected]> 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/sections.h>
53#include <asm/cacheflush.h>
54#include <asm/errno.h>
55#include <linux/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
70static int kprobes_initialized;
71static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
72static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
73
74/* NOTE: change this value only with kprobe_mutex held */
75static bool kprobes_all_disarmed;
76
77/* This protects kprobe_table and optimizing_list */
78static DEFINE_MUTEX(kprobe_mutex);
79static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
80static struct {
81 raw_spinlock_t lock ____cacheline_aligned_in_smp;
82} kretprobe_table_locks[KPROBE_TABLE_SIZE];
83
84static 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 */
90static 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 */
99struct 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
112static int slots_per_page(struct kprobe_insn_cache *c)
113{
114 return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));
115}
116
117enum kprobe_slot_state {
118 SLOT_CLEAN = 0,
119 SLOT_DIRTY = 1,
120 SLOT_USED = 2,
121};
122
123static void *alloc_insn_page(void)
124{
125 return module_alloc(PAGE_SIZE);
126}
127
128static void free_insn_page(void *page)
129{
130 module_memfree(page);
131}
132
133struct 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};
141static 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 */
147kprobe_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 /* Since the slot array is not protected by rcu, we need a mutex */
153 mutex_lock(&c->mutex);
154 retry:
155 rcu_read_lock();
156 list_for_each_entry_rcu(kip, &c->pages, list) {
157 if (kip->nused < slots_per_page(c)) {
158 int i;
159 for (i = 0; i < slots_per_page(c); i++) {
160 if (kip->slot_used[i] == SLOT_CLEAN) {
161 kip->slot_used[i] = SLOT_USED;
162 kip->nused++;
163 slot = kip->insns + (i * c->insn_size);
164 rcu_read_unlock();
165 goto out;
166 }
167 }
168 /* kip->nused is broken. Fix it. */
169 kip->nused = slots_per_page(c);
170 WARN_ON(1);
171 }
172 }
173 rcu_read_unlock();
174
175 /* If there are any garbage slots, collect it and try again. */
176 if (c->nr_garbage && collect_garbage_slots(c) == 0)
177 goto retry;
178
179 /* All out of space. Need to allocate a new page. */
180 kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
181 if (!kip)
182 goto out;
183
184 /*
185 * Use module_alloc so this page is within +/- 2GB of where the
186 * kernel image and loaded module images reside. This is required
187 * so x86_64 can correctly handle the %rip-relative fixups.
188 */
189 kip->insns = c->alloc();
190 if (!kip->insns) {
191 kfree(kip);
192 goto out;
193 }
194 INIT_LIST_HEAD(&kip->list);
195 memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c));
196 kip->slot_used[0] = SLOT_USED;
197 kip->nused = 1;
198 kip->ngarbage = 0;
199 kip->cache = c;
200 list_add_rcu(&kip->list, &c->pages);
201 slot = kip->insns;
202out:
203 mutex_unlock(&c->mutex);
204 return slot;
205}
206
207/* Return 1 if all garbages are collected, otherwise 0. */
208static int collect_one_slot(struct kprobe_insn_page *kip, int idx)
209{
210 kip->slot_used[idx] = SLOT_CLEAN;
211 kip->nused--;
212 if (kip->nused == 0) {
213 /*
214 * Page is no longer in use. Free it unless
215 * it's the last one. We keep the last one
216 * so as not to have to set it up again the
217 * next time somebody inserts a probe.
218 */
219 if (!list_is_singular(&kip->list)) {
220 list_del_rcu(&kip->list);
221 synchronize_rcu();
222 kip->cache->free(kip->insns);
223 kfree(kip);
224 }
225 return 1;
226 }
227 return 0;
228}
229
230static int collect_garbage_slots(struct kprobe_insn_cache *c)
231{
232 struct kprobe_insn_page *kip, *next;
233
234 /* Ensure no-one is interrupted on the garbages */
235 synchronize_sched();
236
237 list_for_each_entry_safe(kip, next, &c->pages, list) {
238 int i;
239 if (kip->ngarbage == 0)
240 continue;
241 kip->ngarbage = 0; /* we will collect all garbages */
242 for (i = 0; i < slots_per_page(c); i++) {
243 if (kip->slot_used[i] == SLOT_DIRTY && collect_one_slot(kip, i))
244 break;
245 }
246 }
247 c->nr_garbage = 0;
248 return 0;
249}
250
251void __free_insn_slot(struct kprobe_insn_cache *c,
252 kprobe_opcode_t *slot, int dirty)
253{
254 struct kprobe_insn_page *kip;
255 long idx;
256
257 mutex_lock(&c->mutex);
258 rcu_read_lock();
259 list_for_each_entry_rcu(kip, &c->pages, list) {
260 idx = ((long)slot - (long)kip->insns) /
261 (c->insn_size * sizeof(kprobe_opcode_t));
262 if (idx >= 0 && idx < slots_per_page(c))
263 goto out;
264 }
265 /* Could not find this slot. */
266 WARN_ON(1);
267 kip = NULL;
268out:
269 rcu_read_unlock();
270 /* Mark and sweep: this may sleep */
271 if (kip) {
272 /* Check double free */
273 WARN_ON(kip->slot_used[idx] != SLOT_USED);
274 if (dirty) {
275 kip->slot_used[idx] = SLOT_DIRTY;
276 kip->ngarbage++;
277 if (++c->nr_garbage > slots_per_page(c))
278 collect_garbage_slots(c);
279 } else {
280 collect_one_slot(kip, idx);
281 }
282 }
283 mutex_unlock(&c->mutex);
284}
285
286/*
287 * Check given address is on the page of kprobe instruction slots.
288 * This will be used for checking whether the address on a stack
289 * is on a text area or not.
290 */
291bool __is_insn_slot_addr(struct kprobe_insn_cache *c, unsigned long addr)
292{
293 struct kprobe_insn_page *kip;
294 bool ret = false;
295
296 rcu_read_lock();
297 list_for_each_entry_rcu(kip, &c->pages, list) {
298 if (addr >= (unsigned long)kip->insns &&
299 addr < (unsigned long)kip->insns + PAGE_SIZE) {
300 ret = true;
301 break;
302 }
303 }
304 rcu_read_unlock();
305
306 return ret;
307}
308
309#ifdef CONFIG_OPTPROBES
310/* For optimized_kprobe buffer */
311struct kprobe_insn_cache kprobe_optinsn_slots = {
312 .mutex = __MUTEX_INITIALIZER(kprobe_optinsn_slots.mutex),
313 .alloc = alloc_insn_page,
314 .free = free_insn_page,
315 .pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
316 /* .insn_size is initialized later */
317 .nr_garbage = 0,
318};
319#endif
320#endif
321
322/* We have preemption disabled.. so it is safe to use __ versions */
323static inline void set_kprobe_instance(struct kprobe *kp)
324{
325 __this_cpu_write(kprobe_instance, kp);
326}
327
328static inline void reset_kprobe_instance(void)
329{
330 __this_cpu_write(kprobe_instance, NULL);
331}
332
333/*
334 * This routine is called either:
335 * - under the kprobe_mutex - during kprobe_[un]register()
336 * OR
337 * - with preemption disabled - from arch/xxx/kernel/kprobes.c
338 */
339struct kprobe *get_kprobe(void *addr)
340{
341 struct hlist_head *head;
342 struct kprobe *p;
343
344 head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
345 hlist_for_each_entry_rcu(p, head, hlist) {
346 if (p->addr == addr)
347 return p;
348 }
349
350 return NULL;
351}
352NOKPROBE_SYMBOL(get_kprobe);
353
354static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs);
355
356/* Return true if the kprobe is an aggregator */
357static inline int kprobe_aggrprobe(struct kprobe *p)
358{
359 return p->pre_handler == aggr_pre_handler;
360}
361
362/* Return true(!0) if the kprobe is unused */
363static inline int kprobe_unused(struct kprobe *p)
364{
365 return kprobe_aggrprobe(p) && kprobe_disabled(p) &&
366 list_empty(&p->list);
367}
368
369/*
370 * Keep all fields in the kprobe consistent
371 */
372static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p)
373{
374 memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t));
375 memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn));
376}
377
378#ifdef CONFIG_OPTPROBES
379/* NOTE: change this value only with kprobe_mutex held */
380static bool kprobes_allow_optimization;
381
382/*
383 * Call all pre_handler on the list, but ignores its return value.
384 * This must be called from arch-dep optimized caller.
385 */
386void opt_pre_handler(struct kprobe *p, struct pt_regs *regs)
387{
388 struct kprobe *kp;
389
390 list_for_each_entry_rcu(kp, &p->list, list) {
391 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
392 set_kprobe_instance(kp);
393 kp->pre_handler(kp, regs);
394 }
395 reset_kprobe_instance();
396 }
397}
398NOKPROBE_SYMBOL(opt_pre_handler);
399
400/* Free optimized instructions and optimized_kprobe */
401static void free_aggr_kprobe(struct kprobe *p)
402{
403 struct optimized_kprobe *op;
404
405 op = container_of(p, struct optimized_kprobe, kp);
406 arch_remove_optimized_kprobe(op);
407 arch_remove_kprobe(p);
408 kfree(op);
409}
410
411/* Return true(!0) if the kprobe is ready for optimization. */
412static inline int kprobe_optready(struct kprobe *p)
413{
414 struct optimized_kprobe *op;
415
416 if (kprobe_aggrprobe(p)) {
417 op = container_of(p, struct optimized_kprobe, kp);
418 return arch_prepared_optinsn(&op->optinsn);
419 }
420
421 return 0;
422}
423
424/* Return true(!0) if the kprobe is disarmed. Note: p must be on hash list */
425static inline int kprobe_disarmed(struct kprobe *p)
426{
427 struct optimized_kprobe *op;
428
429 /* If kprobe is not aggr/opt probe, just return kprobe is disabled */
430 if (!kprobe_aggrprobe(p))
431 return kprobe_disabled(p);
432
433 op = container_of(p, struct optimized_kprobe, kp);
434
435 return kprobe_disabled(p) && list_empty(&op->list);
436}
437
438/* Return true(!0) if the probe is queued on (un)optimizing lists */
439static int kprobe_queued(struct kprobe *p)
440{
441 struct optimized_kprobe *op;
442
443 if (kprobe_aggrprobe(p)) {
444 op = container_of(p, struct optimized_kprobe, kp);
445 if (!list_empty(&op->list))
446 return 1;
447 }
448 return 0;
449}
450
451/*
452 * Return an optimized kprobe whose optimizing code replaces
453 * instructions including addr (exclude breakpoint).
454 */
455static struct kprobe *get_optimized_kprobe(unsigned long addr)
456{
457 int i;
458 struct kprobe *p = NULL;
459 struct optimized_kprobe *op;
460
461 /* Don't check i == 0, since that is a breakpoint case. */
462 for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH; i++)
463 p = get_kprobe((void *)(addr - i));
464
465 if (p && kprobe_optready(p)) {
466 op = container_of(p, struct optimized_kprobe, kp);
467 if (arch_within_optimized_kprobe(op, addr))
468 return p;
469 }
470
471 return NULL;
472}
473
474/* Optimization staging list, protected by kprobe_mutex */
475static LIST_HEAD(optimizing_list);
476static LIST_HEAD(unoptimizing_list);
477static LIST_HEAD(freeing_list);
478
479static void kprobe_optimizer(struct work_struct *work);
480static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
481#define OPTIMIZE_DELAY 5
482
483/*
484 * Optimize (replace a breakpoint with a jump) kprobes listed on
485 * optimizing_list.
486 */
487static void do_optimize_kprobes(void)
488{
489 /* Optimization never be done when disarmed */
490 if (kprobes_all_disarmed || !kprobes_allow_optimization ||
491 list_empty(&optimizing_list))
492 return;
493
494 /*
495 * The optimization/unoptimization refers online_cpus via
496 * stop_machine() and cpu-hotplug modifies online_cpus.
497 * And same time, text_mutex will be held in cpu-hotplug and here.
498 * This combination can cause a deadlock (cpu-hotplug try to lock
499 * text_mutex but stop_machine can not be done because online_cpus
500 * has been changed)
501 * To avoid this deadlock, we need to call get_online_cpus()
502 * for preventing cpu-hotplug outside of text_mutex locking.
503 */
504 get_online_cpus();
505 mutex_lock(&text_mutex);
506 arch_optimize_kprobes(&optimizing_list);
507 mutex_unlock(&text_mutex);
508 put_online_cpus();
509}
510
511/*
512 * Unoptimize (replace a jump with a breakpoint and remove the breakpoint
513 * if need) kprobes listed on unoptimizing_list.
514 */
515static void do_unoptimize_kprobes(void)
516{
517 struct optimized_kprobe *op, *tmp;
518
519 /* Unoptimization must be done anytime */
520 if (list_empty(&unoptimizing_list))
521 return;
522
523 /* Ditto to do_optimize_kprobes */
524 get_online_cpus();
525 mutex_lock(&text_mutex);
526 arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list);
527 /* Loop free_list for disarming */
528 list_for_each_entry_safe(op, tmp, &freeing_list, list) {
529 /* Disarm probes if marked disabled */
530 if (kprobe_disabled(&op->kp))
531 arch_disarm_kprobe(&op->kp);
532 if (kprobe_unused(&op->kp)) {
533 /*
534 * Remove unused probes from hash list. After waiting
535 * for synchronization, these probes are reclaimed.
536 * (reclaiming is done by do_free_cleaned_kprobes.)
537 */
538 hlist_del_rcu(&op->kp.hlist);
539 } else
540 list_del_init(&op->list);
541 }
542 mutex_unlock(&text_mutex);
543 put_online_cpus();
544}
545
546/* Reclaim all kprobes on the free_list */
547static void do_free_cleaned_kprobes(void)
548{
549 struct optimized_kprobe *op, *tmp;
550
551 list_for_each_entry_safe(op, tmp, &freeing_list, list) {
552 BUG_ON(!kprobe_unused(&op->kp));
553 list_del_init(&op->list);
554 free_aggr_kprobe(&op->kp);
555 }
556}
557
558/* Start optimizer after OPTIMIZE_DELAY passed */
559static void kick_kprobe_optimizer(void)
560{
561 schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
562}
563
564/* Kprobe jump optimizer */
565static void kprobe_optimizer(struct work_struct *work)
566{
567 mutex_lock(&kprobe_mutex);
568 /* Lock modules while optimizing kprobes */
569 mutex_lock(&module_mutex);
570
571 /*
572 * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
573 * kprobes before waiting for quiesence period.
574 */
575 do_unoptimize_kprobes();
576
577 /*
578 * Step 2: Wait for quiesence period to ensure all running interrupts
579 * are done. Because optprobe may modify multiple instructions
580 * there is a chance that Nth instruction is interrupted. In that
581 * case, running interrupt can return to 2nd-Nth byte of jump
582 * instruction. This wait is for avoiding it.
583 */
584 synchronize_sched();
585
586 /* Step 3: Optimize kprobes after quiesence period */
587 do_optimize_kprobes();
588
589 /* Step 4: Free cleaned kprobes after quiesence period */
590 do_free_cleaned_kprobes();
591
592 mutex_unlock(&module_mutex);
593 mutex_unlock(&kprobe_mutex);
594
595 /* Step 5: Kick optimizer again if needed */
596 if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
597 kick_kprobe_optimizer();
598}
599
600/* Wait for completing optimization and unoptimization */
601static void wait_for_kprobe_optimizer(void)
602{
603 mutex_lock(&kprobe_mutex);
604
605 while (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) {
606 mutex_unlock(&kprobe_mutex);
607
608 /* this will also make optimizing_work execute immmediately */
609 flush_delayed_work(&optimizing_work);
610 /* @optimizing_work might not have been queued yet, relax */
611 cpu_relax();
612
613 mutex_lock(&kprobe_mutex);
614 }
615
616 mutex_unlock(&kprobe_mutex);
617}
618
619/* Optimize kprobe if p is ready to be optimized */
620static void optimize_kprobe(struct kprobe *p)
621{
622 struct optimized_kprobe *op;
623
624 /* Check if the kprobe is disabled or not ready for optimization. */
625 if (!kprobe_optready(p) || !kprobes_allow_optimization ||
626 (kprobe_disabled(p) || kprobes_all_disarmed))
627 return;
628
629 /* Both of break_handler and post_handler are not supported. */
630 if (p->break_handler || p->post_handler)
631 return;
632
633 op = container_of(p, struct optimized_kprobe, kp);
634
635 /* Check there is no other kprobes at the optimized instructions */
636 if (arch_check_optimized_kprobe(op) < 0)
637 return;
638
639 /* Check if it is already optimized. */
640 if (op->kp.flags & KPROBE_FLAG_OPTIMIZED)
641 return;
642 op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
643
644 if (!list_empty(&op->list))
645 /* This is under unoptimizing. Just dequeue the probe */
646 list_del_init(&op->list);
647 else {
648 list_add(&op->list, &optimizing_list);
649 kick_kprobe_optimizer();
650 }
651}
652
653/* Short cut to direct unoptimizing */
654static void force_unoptimize_kprobe(struct optimized_kprobe *op)
655{
656 get_online_cpus();
657 arch_unoptimize_kprobe(op);
658 put_online_cpus();
659 if (kprobe_disabled(&op->kp))
660 arch_disarm_kprobe(&op->kp);
661}
662
663/* Unoptimize a kprobe if p is optimized */
664static void unoptimize_kprobe(struct kprobe *p, bool force)
665{
666 struct optimized_kprobe *op;
667
668 if (!kprobe_aggrprobe(p) || kprobe_disarmed(p))
669 return; /* This is not an optprobe nor optimized */
670
671 op = container_of(p, struct optimized_kprobe, kp);
672 if (!kprobe_optimized(p)) {
673 /* Unoptimized or unoptimizing case */
674 if (force && !list_empty(&op->list)) {
675 /*
676 * Only if this is unoptimizing kprobe and forced,
677 * forcibly unoptimize it. (No need to unoptimize
678 * unoptimized kprobe again :)
679 */
680 list_del_init(&op->list);
681 force_unoptimize_kprobe(op);
682 }
683 return;
684 }
685
686 op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
687 if (!list_empty(&op->list)) {
688 /* Dequeue from the optimization queue */
689 list_del_init(&op->list);
690 return;
691 }
692 /* Optimized kprobe case */
693 if (force)
694 /* Forcibly update the code: this is a special case */
695 force_unoptimize_kprobe(op);
696 else {
697 list_add(&op->list, &unoptimizing_list);
698 kick_kprobe_optimizer();
699 }
700}
701
702/* Cancel unoptimizing for reusing */
703static void reuse_unused_kprobe(struct kprobe *ap)
704{
705 struct optimized_kprobe *op;
706
707 BUG_ON(!kprobe_unused(ap));
708 /*
709 * Unused kprobe MUST be on the way of delayed unoptimizing (means
710 * there is still a relative jump) and disabled.
711 */
712 op = container_of(ap, struct optimized_kprobe, kp);
713 if (unlikely(list_empty(&op->list)))
714 printk(KERN_WARNING "Warning: found a stray unused "
715 "aggrprobe@%p\n", ap->addr);
716 /* Enable the probe again */
717 ap->flags &= ~KPROBE_FLAG_DISABLED;
718 /* Optimize it again (remove from op->list) */
719 BUG_ON(!kprobe_optready(ap));
720 optimize_kprobe(ap);
721}
722
723/* Remove optimized instructions */
724static void kill_optimized_kprobe(struct kprobe *p)
725{
726 struct optimized_kprobe *op;
727
728 op = container_of(p, struct optimized_kprobe, kp);
729 if (!list_empty(&op->list))
730 /* Dequeue from the (un)optimization queue */
731 list_del_init(&op->list);
732 op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
733
734 if (kprobe_unused(p)) {
735 /* Enqueue if it is unused */
736 list_add(&op->list, &freeing_list);
737 /*
738 * Remove unused probes from the hash list. After waiting
739 * for synchronization, this probe is reclaimed.
740 * (reclaiming is done by do_free_cleaned_kprobes().)
741 */
742 hlist_del_rcu(&op->kp.hlist);
743 }
744
745 /* Don't touch the code, because it is already freed. */
746 arch_remove_optimized_kprobe(op);
747}
748
749/* Try to prepare optimized instructions */
750static void prepare_optimized_kprobe(struct kprobe *p)
751{
752 struct optimized_kprobe *op;
753
754 op = container_of(p, struct optimized_kprobe, kp);
755 arch_prepare_optimized_kprobe(op, p);
756}
757
758/* Allocate new optimized_kprobe and try to prepare optimized instructions */
759static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
760{
761 struct optimized_kprobe *op;
762
763 op = kzalloc(sizeof(struct optimized_kprobe), GFP_KERNEL);
764 if (!op)
765 return NULL;
766
767 INIT_LIST_HEAD(&op->list);
768 op->kp.addr = p->addr;
769 arch_prepare_optimized_kprobe(op, p);
770
771 return &op->kp;
772}
773
774static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p);
775
776/*
777 * Prepare an optimized_kprobe and optimize it
778 * NOTE: p must be a normal registered kprobe
779 */
780static void try_to_optimize_kprobe(struct kprobe *p)
781{
782 struct kprobe *ap;
783 struct optimized_kprobe *op;
784
785 /* Impossible to optimize ftrace-based kprobe */
786 if (kprobe_ftrace(p))
787 return;
788
789 /* For preparing optimization, jump_label_text_reserved() is called */
790 jump_label_lock();
791 mutex_lock(&text_mutex);
792
793 ap = alloc_aggr_kprobe(p);
794 if (!ap)
795 goto out;
796
797 op = container_of(ap, struct optimized_kprobe, kp);
798 if (!arch_prepared_optinsn(&op->optinsn)) {
799 /* If failed to setup optimizing, fallback to kprobe */
800 arch_remove_optimized_kprobe(op);
801 kfree(op);
802 goto out;
803 }
804
805 init_aggr_kprobe(ap, p);
806 optimize_kprobe(ap); /* This just kicks optimizer thread */
807
808out:
809 mutex_unlock(&text_mutex);
810 jump_label_unlock();
811}
812
813#ifdef CONFIG_SYSCTL
814static void optimize_all_kprobes(void)
815{
816 struct hlist_head *head;
817 struct kprobe *p;
818 unsigned int i;
819
820 mutex_lock(&kprobe_mutex);
821 /* If optimization is already allowed, just return */
822 if (kprobes_allow_optimization)
823 goto out;
824
825 kprobes_allow_optimization = true;
826 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
827 head = &kprobe_table[i];
828 hlist_for_each_entry_rcu(p, head, hlist)
829 if (!kprobe_disabled(p))
830 optimize_kprobe(p);
831 }
832 printk(KERN_INFO "Kprobes globally optimized\n");
833out:
834 mutex_unlock(&kprobe_mutex);
835}
836
837static void unoptimize_all_kprobes(void)
838{
839 struct hlist_head *head;
840 struct kprobe *p;
841 unsigned int i;
842
843 mutex_lock(&kprobe_mutex);
844 /* If optimization is already prohibited, just return */
845 if (!kprobes_allow_optimization) {
846 mutex_unlock(&kprobe_mutex);
847 return;
848 }
849
850 kprobes_allow_optimization = false;
851 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
852 head = &kprobe_table[i];
853 hlist_for_each_entry_rcu(p, head, hlist) {
854 if (!kprobe_disabled(p))
855 unoptimize_kprobe(p, false);
856 }
857 }
858 mutex_unlock(&kprobe_mutex);
859
860 /* Wait for unoptimizing completion */
861 wait_for_kprobe_optimizer();
862 printk(KERN_INFO "Kprobes globally unoptimized\n");
863}
864
865static DEFINE_MUTEX(kprobe_sysctl_mutex);
866int sysctl_kprobes_optimization;
867int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
868 void __user *buffer, size_t *length,
869 loff_t *ppos)
870{
871 int ret;
872
873 mutex_lock(&kprobe_sysctl_mutex);
874 sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0;
875 ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
876
877 if (sysctl_kprobes_optimization)
878 optimize_all_kprobes();
879 else
880 unoptimize_all_kprobes();
881 mutex_unlock(&kprobe_sysctl_mutex);
882
883 return ret;
884}
885#endif /* CONFIG_SYSCTL */
886
887/* Put a breakpoint for a probe. Must be called with text_mutex locked */
888static void __arm_kprobe(struct kprobe *p)
889{
890 struct kprobe *_p;
891
892 /* Check collision with other optimized kprobes */
893 _p = get_optimized_kprobe((unsigned long)p->addr);
894 if (unlikely(_p))
895 /* Fallback to unoptimized kprobe */
896 unoptimize_kprobe(_p, true);
897
898 arch_arm_kprobe(p);
899 optimize_kprobe(p); /* Try to optimize (add kprobe to a list) */
900}
901
902/* Remove the breakpoint of a probe. Must be called with text_mutex locked */
903static void __disarm_kprobe(struct kprobe *p, bool reopt)
904{
905 struct kprobe *_p;
906
907 /* Try to unoptimize */
908 unoptimize_kprobe(p, kprobes_all_disarmed);
909
910 if (!kprobe_queued(p)) {
911 arch_disarm_kprobe(p);
912 /* If another kprobe was blocked, optimize it. */
913 _p = get_optimized_kprobe((unsigned long)p->addr);
914 if (unlikely(_p) && reopt)
915 optimize_kprobe(_p);
916 }
917 /* TODO: reoptimize others after unoptimized this probe */
918}
919
920#else /* !CONFIG_OPTPROBES */
921
922#define optimize_kprobe(p) do {} while (0)
923#define unoptimize_kprobe(p, f) do {} while (0)
924#define kill_optimized_kprobe(p) do {} while (0)
925#define prepare_optimized_kprobe(p) do {} while (0)
926#define try_to_optimize_kprobe(p) do {} while (0)
927#define __arm_kprobe(p) arch_arm_kprobe(p)
928#define __disarm_kprobe(p, o) arch_disarm_kprobe(p)
929#define kprobe_disarmed(p) kprobe_disabled(p)
930#define wait_for_kprobe_optimizer() do {} while (0)
931
932/* There should be no unused kprobes can be reused without optimization */
933static void reuse_unused_kprobe(struct kprobe *ap)
934{
935 printk(KERN_ERR "Error: There should be no unused kprobe here.\n");
936 BUG_ON(kprobe_unused(ap));
937}
938
939static void free_aggr_kprobe(struct kprobe *p)
940{
941 arch_remove_kprobe(p);
942 kfree(p);
943}
944
945static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
946{
947 return kzalloc(sizeof(struct kprobe), GFP_KERNEL);
948}
949#endif /* CONFIG_OPTPROBES */
950
951#ifdef CONFIG_KPROBES_ON_FTRACE
952static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
953 .func = kprobe_ftrace_handler,
954 .flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_IPMODIFY,
955};
956static int kprobe_ftrace_enabled;
957
958/* Must ensure p->addr is really on ftrace */
959static int prepare_kprobe(struct kprobe *p)
960{
961 if (!kprobe_ftrace(p))
962 return arch_prepare_kprobe(p);
963
964 return arch_prepare_kprobe_ftrace(p);
965}
966
967/* Caller must lock kprobe_mutex */
968static void arm_kprobe_ftrace(struct kprobe *p)
969{
970 int ret;
971
972 ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
973 (unsigned long)p->addr, 0, 0);
974 WARN(ret < 0, "Failed to arm kprobe-ftrace at %p (%d)\n", p->addr, ret);
975 kprobe_ftrace_enabled++;
976 if (kprobe_ftrace_enabled == 1) {
977 ret = register_ftrace_function(&kprobe_ftrace_ops);
978 WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
979 }
980}
981
982/* Caller must lock kprobe_mutex */
983static void disarm_kprobe_ftrace(struct kprobe *p)
984{
985 int ret;
986
987 kprobe_ftrace_enabled--;
988 if (kprobe_ftrace_enabled == 0) {
989 ret = unregister_ftrace_function(&kprobe_ftrace_ops);
990 WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
991 }
992 ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
993 (unsigned long)p->addr, 1, 0);
994 WARN(ret < 0, "Failed to disarm kprobe-ftrace at %p (%d)\n", p->addr, ret);
995}
996#else /* !CONFIG_KPROBES_ON_FTRACE */
997#define prepare_kprobe(p) arch_prepare_kprobe(p)
998#define arm_kprobe_ftrace(p) do {} while (0)
999#define disarm_kprobe_ftrace(p) do {} while (0)
1000#endif
1001
1002/* Arm a kprobe with text_mutex */
1003static void arm_kprobe(struct kprobe *kp)
1004{
1005 if (unlikely(kprobe_ftrace(kp))) {
1006 arm_kprobe_ftrace(kp);
1007 return;
1008 }
1009 /*
1010 * Here, since __arm_kprobe() doesn't use stop_machine(),
1011 * this doesn't cause deadlock on text_mutex. So, we don't
1012 * need get_online_cpus().
1013 */
1014 mutex_lock(&text_mutex);
1015 __arm_kprobe(kp);
1016 mutex_unlock(&text_mutex);
1017}
1018
1019/* Disarm a kprobe with text_mutex */
1020static void disarm_kprobe(struct kprobe *kp, bool reopt)
1021{
1022 if (unlikely(kprobe_ftrace(kp))) {
1023 disarm_kprobe_ftrace(kp);
1024 return;
1025 }
1026 /* Ditto */
1027 mutex_lock(&text_mutex);
1028 __disarm_kprobe(kp, reopt);
1029 mutex_unlock(&text_mutex);
1030}
1031
1032/*
1033 * Aggregate handlers for multiple kprobes support - these handlers
1034 * take care of invoking the individual kprobe handlers on p->list
1035 */
1036static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
1037{
1038 struct kprobe *kp;
1039
1040 list_for_each_entry_rcu(kp, &p->list, list) {
1041 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
1042 set_kprobe_instance(kp);
1043 if (kp->pre_handler(kp, regs))
1044 return 1;
1045 }
1046 reset_kprobe_instance();
1047 }
1048 return 0;
1049}
1050NOKPROBE_SYMBOL(aggr_pre_handler);
1051
1052static void aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
1053 unsigned long flags)
1054{
1055 struct kprobe *kp;
1056
1057 list_for_each_entry_rcu(kp, &p->list, list) {
1058 if (kp->post_handler && likely(!kprobe_disabled(kp))) {
1059 set_kprobe_instance(kp);
1060 kp->post_handler(kp, regs, flags);
1061 reset_kprobe_instance();
1062 }
1063 }
1064}
1065NOKPROBE_SYMBOL(aggr_post_handler);
1066
1067static int aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
1068 int trapnr)
1069{
1070 struct kprobe *cur = __this_cpu_read(kprobe_instance);
1071
1072 /*
1073 * if we faulted "during" the execution of a user specified
1074 * probe handler, invoke just that probe's fault handler
1075 */
1076 if (cur && cur->fault_handler) {
1077 if (cur->fault_handler(cur, regs, trapnr))
1078 return 1;
1079 }
1080 return 0;
1081}
1082NOKPROBE_SYMBOL(aggr_fault_handler);
1083
1084static int aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
1085{
1086 struct kprobe *cur = __this_cpu_read(kprobe_instance);
1087 int ret = 0;
1088
1089 if (cur && cur->break_handler) {
1090 if (cur->break_handler(cur, regs))
1091 ret = 1;
1092 }
1093 reset_kprobe_instance();
1094 return ret;
1095}
1096NOKPROBE_SYMBOL(aggr_break_handler);
1097
1098/* Walks the list and increments nmissed count for multiprobe case */
1099void kprobes_inc_nmissed_count(struct kprobe *p)
1100{
1101 struct kprobe *kp;
1102 if (!kprobe_aggrprobe(p)) {
1103 p->nmissed++;
1104 } else {
1105 list_for_each_entry_rcu(kp, &p->list, list)
1106 kp->nmissed++;
1107 }
1108 return;
1109}
1110NOKPROBE_SYMBOL(kprobes_inc_nmissed_count);
1111
1112void recycle_rp_inst(struct kretprobe_instance *ri,
1113 struct hlist_head *head)
1114{
1115 struct kretprobe *rp = ri->rp;
1116
1117 /* remove rp inst off the rprobe_inst_table */
1118 hlist_del(&ri->hlist);
1119 INIT_HLIST_NODE(&ri->hlist);
1120 if (likely(rp)) {
1121 raw_spin_lock(&rp->lock);
1122 hlist_add_head(&ri->hlist, &rp->free_instances);
1123 raw_spin_unlock(&rp->lock);
1124 } else
1125 /* Unregistering */
1126 hlist_add_head(&ri->hlist, head);
1127}
1128NOKPROBE_SYMBOL(recycle_rp_inst);
1129
1130void kretprobe_hash_lock(struct task_struct *tsk,
1131 struct hlist_head **head, unsigned long *flags)
1132__acquires(hlist_lock)
1133{
1134 unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1135 raw_spinlock_t *hlist_lock;
1136
1137 *head = &kretprobe_inst_table[hash];
1138 hlist_lock = kretprobe_table_lock_ptr(hash);
1139 raw_spin_lock_irqsave(hlist_lock, *flags);
1140}
1141NOKPROBE_SYMBOL(kretprobe_hash_lock);
1142
1143static void kretprobe_table_lock(unsigned long hash,
1144 unsigned long *flags)
1145__acquires(hlist_lock)
1146{
1147 raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1148 raw_spin_lock_irqsave(hlist_lock, *flags);
1149}
1150NOKPROBE_SYMBOL(kretprobe_table_lock);
1151
1152void kretprobe_hash_unlock(struct task_struct *tsk,
1153 unsigned long *flags)
1154__releases(hlist_lock)
1155{
1156 unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1157 raw_spinlock_t *hlist_lock;
1158
1159 hlist_lock = kretprobe_table_lock_ptr(hash);
1160 raw_spin_unlock_irqrestore(hlist_lock, *flags);
1161}
1162NOKPROBE_SYMBOL(kretprobe_hash_unlock);
1163
1164static void kretprobe_table_unlock(unsigned long hash,
1165 unsigned long *flags)
1166__releases(hlist_lock)
1167{
1168 raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1169 raw_spin_unlock_irqrestore(hlist_lock, *flags);
1170}
1171NOKPROBE_SYMBOL(kretprobe_table_unlock);
1172
1173/*
1174 * This function is called from finish_task_switch when task tk becomes dead,
1175 * so that we can recycle any function-return probe instances associated
1176 * with this task. These left over instances represent probed functions
1177 * that have been called but will never return.
1178 */
1179void kprobe_flush_task(struct task_struct *tk)
1180{
1181 struct kretprobe_instance *ri;
1182 struct hlist_head *head, empty_rp;
1183 struct hlist_node *tmp;
1184 unsigned long hash, flags = 0;
1185
1186 if (unlikely(!kprobes_initialized))
1187 /* Early boot. kretprobe_table_locks not yet initialized. */
1188 return;
1189
1190 INIT_HLIST_HEAD(&empty_rp);
1191 hash = hash_ptr(tk, KPROBE_HASH_BITS);
1192 head = &kretprobe_inst_table[hash];
1193 kretprobe_table_lock(hash, &flags);
1194 hlist_for_each_entry_safe(ri, tmp, head, hlist) {
1195 if (ri->task == tk)
1196 recycle_rp_inst(ri, &empty_rp);
1197 }
1198 kretprobe_table_unlock(hash, &flags);
1199 hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
1200 hlist_del(&ri->hlist);
1201 kfree(ri);
1202 }
1203}
1204NOKPROBE_SYMBOL(kprobe_flush_task);
1205
1206static inline void free_rp_inst(struct kretprobe *rp)
1207{
1208 struct kretprobe_instance *ri;
1209 struct hlist_node *next;
1210
1211 hlist_for_each_entry_safe(ri, next, &rp->free_instances, hlist) {
1212 hlist_del(&ri->hlist);
1213 kfree(ri);
1214 }
1215}
1216
1217static void cleanup_rp_inst(struct kretprobe *rp)
1218{
1219 unsigned long flags, hash;
1220 struct kretprobe_instance *ri;
1221 struct hlist_node *next;
1222 struct hlist_head *head;
1223
1224 /* No race here */
1225 for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
1226 kretprobe_table_lock(hash, &flags);
1227 head = &kretprobe_inst_table[hash];
1228 hlist_for_each_entry_safe(ri, next, head, hlist) {
1229 if (ri->rp == rp)
1230 ri->rp = NULL;
1231 }
1232 kretprobe_table_unlock(hash, &flags);
1233 }
1234 free_rp_inst(rp);
1235}
1236NOKPROBE_SYMBOL(cleanup_rp_inst);
1237
1238/*
1239* Add the new probe to ap->list. Fail if this is the
1240* second jprobe at the address - two jprobes can't coexist
1241*/
1242static int add_new_kprobe(struct kprobe *ap, struct kprobe *p)
1243{
1244 BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
1245
1246 if (p->break_handler || p->post_handler)
1247 unoptimize_kprobe(ap, true); /* Fall back to normal kprobe */
1248
1249 if (p->break_handler) {
1250 if (ap->break_handler)
1251 return -EEXIST;
1252 list_add_tail_rcu(&p->list, &ap->list);
1253 ap->break_handler = aggr_break_handler;
1254 } else
1255 list_add_rcu(&p->list, &ap->list);
1256 if (p->post_handler && !ap->post_handler)
1257 ap->post_handler = aggr_post_handler;
1258
1259 return 0;
1260}
1261
1262/*
1263 * Fill in the required fields of the "manager kprobe". Replace the
1264 * earlier kprobe in the hlist with the manager kprobe
1265 */
1266static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
1267{
1268 /* Copy p's insn slot to ap */
1269 copy_kprobe(p, ap);
1270 flush_insn_slot(ap);
1271 ap->addr = p->addr;
1272 ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED;
1273 ap->pre_handler = aggr_pre_handler;
1274 ap->fault_handler = aggr_fault_handler;
1275 /* We don't care the kprobe which has gone. */
1276 if (p->post_handler && !kprobe_gone(p))
1277 ap->post_handler = aggr_post_handler;
1278 if (p->break_handler && !kprobe_gone(p))
1279 ap->break_handler = aggr_break_handler;
1280
1281 INIT_LIST_HEAD(&ap->list);
1282 INIT_HLIST_NODE(&ap->hlist);
1283
1284 list_add_rcu(&p->list, &ap->list);
1285 hlist_replace_rcu(&p->hlist, &ap->hlist);
1286}
1287
1288/*
1289 * This is the second or subsequent kprobe at the address - handle
1290 * the intricacies
1291 */
1292static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p)
1293{
1294 int ret = 0;
1295 struct kprobe *ap = orig_p;
1296
1297 /* For preparing optimization, jump_label_text_reserved() is called */
1298 jump_label_lock();
1299 /*
1300 * Get online CPUs to avoid text_mutex deadlock.with stop machine,
1301 * which is invoked by unoptimize_kprobe() in add_new_kprobe()
1302 */
1303 get_online_cpus();
1304 mutex_lock(&text_mutex);
1305
1306 if (!kprobe_aggrprobe(orig_p)) {
1307 /* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */
1308 ap = alloc_aggr_kprobe(orig_p);
1309 if (!ap) {
1310 ret = -ENOMEM;
1311 goto out;
1312 }
1313 init_aggr_kprobe(ap, orig_p);
1314 } else if (kprobe_unused(ap))
1315 /* This probe is going to die. Rescue it */
1316 reuse_unused_kprobe(ap);
1317
1318 if (kprobe_gone(ap)) {
1319 /*
1320 * Attempting to insert new probe at the same location that
1321 * had a probe in the module vaddr area which already
1322 * freed. So, the instruction slot has already been
1323 * released. We need a new slot for the new probe.
1324 */
1325 ret = arch_prepare_kprobe(ap);
1326 if (ret)
1327 /*
1328 * Even if fail to allocate new slot, don't need to
1329 * free aggr_probe. It will be used next time, or
1330 * freed by unregister_kprobe.
1331 */
1332 goto out;
1333
1334 /* Prepare optimized instructions if possible. */
1335 prepare_optimized_kprobe(ap);
1336
1337 /*
1338 * Clear gone flag to prevent allocating new slot again, and
1339 * set disabled flag because it is not armed yet.
1340 */
1341 ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
1342 | KPROBE_FLAG_DISABLED;
1343 }
1344
1345 /* Copy ap's insn slot to p */
1346 copy_kprobe(ap, p);
1347 ret = add_new_kprobe(ap, p);
1348
1349out:
1350 mutex_unlock(&text_mutex);
1351 put_online_cpus();
1352 jump_label_unlock();
1353
1354 if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) {
1355 ap->flags &= ~KPROBE_FLAG_DISABLED;
1356 if (!kprobes_all_disarmed)
1357 /* Arm the breakpoint again. */
1358 arm_kprobe(ap);
1359 }
1360 return ret;
1361}
1362
1363bool __weak arch_within_kprobe_blacklist(unsigned long addr)
1364{
1365 /* The __kprobes marked functions and entry code must not be probed */
1366 return addr >= (unsigned long)__kprobes_text_start &&
1367 addr < (unsigned long)__kprobes_text_end;
1368}
1369
1370bool within_kprobe_blacklist(unsigned long addr)
1371{
1372 struct kprobe_blacklist_entry *ent;
1373
1374 if (arch_within_kprobe_blacklist(addr))
1375 return true;
1376 /*
1377 * If there exists a kprobe_blacklist, verify and
1378 * fail any probe registration in the prohibited area
1379 */
1380 list_for_each_entry(ent, &kprobe_blacklist, list) {
1381 if (addr >= ent->start_addr && addr < ent->end_addr)
1382 return true;
1383 }
1384
1385 return false;
1386}
1387
1388/*
1389 * If we have a symbol_name argument, look it up and add the offset field
1390 * to it. This way, we can specify a relative address to a symbol.
1391 * This returns encoded errors if it fails to look up symbol or invalid
1392 * combination of parameters.
1393 */
1394static kprobe_opcode_t *kprobe_addr(struct kprobe *p)
1395{
1396 kprobe_opcode_t *addr = p->addr;
1397
1398 if ((p->symbol_name && p->addr) ||
1399 (!p->symbol_name && !p->addr))
1400 goto invalid;
1401
1402 if (p->symbol_name) {
1403 kprobe_lookup_name(p->symbol_name, addr);
1404 if (!addr)
1405 return ERR_PTR(-ENOENT);
1406 }
1407
1408 addr = (kprobe_opcode_t *)(((char *)addr) + p->offset);
1409 if (addr)
1410 return addr;
1411
1412invalid:
1413 return ERR_PTR(-EINVAL);
1414}
1415
1416/* Check passed kprobe is valid and return kprobe in kprobe_table. */
1417static struct kprobe *__get_valid_kprobe(struct kprobe *p)
1418{
1419 struct kprobe *ap, *list_p;
1420
1421 ap = get_kprobe(p->addr);
1422 if (unlikely(!ap))
1423 return NULL;
1424
1425 if (p != ap) {
1426 list_for_each_entry_rcu(list_p, &ap->list, list)
1427 if (list_p == p)
1428 /* kprobe p is a valid probe */
1429 goto valid;
1430 return NULL;
1431 }
1432valid:
1433 return ap;
1434}
1435
1436/* Return error if the kprobe is being re-registered */
1437static inline int check_kprobe_rereg(struct kprobe *p)
1438{
1439 int ret = 0;
1440
1441 mutex_lock(&kprobe_mutex);
1442 if (__get_valid_kprobe(p))
1443 ret = -EINVAL;
1444 mutex_unlock(&kprobe_mutex);
1445
1446 return ret;
1447}
1448
1449int __weak arch_check_ftrace_location(struct kprobe *p)
1450{
1451 unsigned long ftrace_addr;
1452
1453 ftrace_addr = ftrace_location((unsigned long)p->addr);
1454 if (ftrace_addr) {
1455#ifdef CONFIG_KPROBES_ON_FTRACE
1456 /* Given address is not on the instruction boundary */
1457 if ((unsigned long)p->addr != ftrace_addr)
1458 return -EILSEQ;
1459 p->flags |= KPROBE_FLAG_FTRACE;
1460#else /* !CONFIG_KPROBES_ON_FTRACE */
1461 return -EINVAL;
1462#endif
1463 }
1464 return 0;
1465}
1466
1467static int check_kprobe_address_safe(struct kprobe *p,
1468 struct module **probed_mod)
1469{
1470 int ret;
1471
1472 ret = arch_check_ftrace_location(p);
1473 if (ret)
1474 return ret;
1475 jump_label_lock();
1476 preempt_disable();
1477
1478 /* Ensure it is not in reserved area nor out of text */
1479 if (!kernel_text_address((unsigned long) p->addr) ||
1480 within_kprobe_blacklist((unsigned long) p->addr) ||
1481 jump_label_text_reserved(p->addr, p->addr)) {
1482 ret = -EINVAL;
1483 goto out;
1484 }
1485
1486 /* Check if are we probing a module */
1487 *probed_mod = __module_text_address((unsigned long) p->addr);
1488 if (*probed_mod) {
1489 /*
1490 * We must hold a refcount of the probed module while updating
1491 * its code to prohibit unexpected unloading.
1492 */
1493 if (unlikely(!try_module_get(*probed_mod))) {
1494 ret = -ENOENT;
1495 goto out;
1496 }
1497
1498 /*
1499 * If the module freed .init.text, we couldn't insert
1500 * kprobes in there.
1501 */
1502 if (within_module_init((unsigned long)p->addr, *probed_mod) &&
1503 (*probed_mod)->state != MODULE_STATE_COMING) {
1504 module_put(*probed_mod);
1505 *probed_mod = NULL;
1506 ret = -ENOENT;
1507 }
1508 }
1509out:
1510 preempt_enable();
1511 jump_label_unlock();
1512
1513 return ret;
1514}
1515
1516int register_kprobe(struct kprobe *p)
1517{
1518 int ret;
1519 struct kprobe *old_p;
1520 struct module *probed_mod;
1521 kprobe_opcode_t *addr;
1522
1523 /* Adjust probe address from symbol */
1524 addr = kprobe_addr(p);
1525 if (IS_ERR(addr))
1526 return PTR_ERR(addr);
1527 p->addr = addr;
1528
1529 ret = check_kprobe_rereg(p);
1530 if (ret)
1531 return ret;
1532
1533 /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
1534 p->flags &= KPROBE_FLAG_DISABLED;
1535 p->nmissed = 0;
1536 INIT_LIST_HEAD(&p->list);
1537
1538 ret = check_kprobe_address_safe(p, &probed_mod);
1539 if (ret)
1540 return ret;
1541
1542 mutex_lock(&kprobe_mutex);
1543
1544 old_p = get_kprobe(p->addr);
1545 if (old_p) {
1546 /* Since this may unoptimize old_p, locking text_mutex. */
1547 ret = register_aggr_kprobe(old_p, p);
1548 goto out;
1549 }
1550
1551 mutex_lock(&text_mutex); /* Avoiding text modification */
1552 ret = prepare_kprobe(p);
1553 mutex_unlock(&text_mutex);
1554 if (ret)
1555 goto out;
1556
1557 INIT_HLIST_NODE(&p->hlist);
1558 hlist_add_head_rcu(&p->hlist,
1559 &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
1560
1561 if (!kprobes_all_disarmed && !kprobe_disabled(p))
1562 arm_kprobe(p);
1563
1564 /* Try to optimize kprobe */
1565 try_to_optimize_kprobe(p);
1566
1567out:
1568 mutex_unlock(&kprobe_mutex);
1569
1570 if (probed_mod)
1571 module_put(probed_mod);
1572
1573 return ret;
1574}
1575EXPORT_SYMBOL_GPL(register_kprobe);
1576
1577/* Check if all probes on the aggrprobe are disabled */
1578static int aggr_kprobe_disabled(struct kprobe *ap)
1579{
1580 struct kprobe *kp;
1581
1582 list_for_each_entry_rcu(kp, &ap->list, list)
1583 if (!kprobe_disabled(kp))
1584 /*
1585 * There is an active probe on the list.
1586 * We can't disable this ap.
1587 */
1588 return 0;
1589
1590 return 1;
1591}
1592
1593/* Disable one kprobe: Make sure called under kprobe_mutex is locked */
1594static struct kprobe *__disable_kprobe(struct kprobe *p)
1595{
1596 struct kprobe *orig_p;
1597
1598 /* Get an original kprobe for return */
1599 orig_p = __get_valid_kprobe(p);
1600 if (unlikely(orig_p == NULL))
1601 return NULL;
1602
1603 if (!kprobe_disabled(p)) {
1604 /* Disable probe if it is a child probe */
1605 if (p != orig_p)
1606 p->flags |= KPROBE_FLAG_DISABLED;
1607
1608 /* Try to disarm and disable this/parent probe */
1609 if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
1610 /*
1611 * If kprobes_all_disarmed is set, orig_p
1612 * should have already been disarmed, so
1613 * skip unneed disarming process.
1614 */
1615 if (!kprobes_all_disarmed)
1616 disarm_kprobe(orig_p, true);
1617 orig_p->flags |= KPROBE_FLAG_DISABLED;
1618 }
1619 }
1620
1621 return orig_p;
1622}
1623
1624/*
1625 * Unregister a kprobe without a scheduler synchronization.
1626 */
1627static int __unregister_kprobe_top(struct kprobe *p)
1628{
1629 struct kprobe *ap, *list_p;
1630
1631 /* Disable kprobe. This will disarm it if needed. */
1632 ap = __disable_kprobe(p);
1633 if (ap == NULL)
1634 return -EINVAL;
1635
1636 if (ap == p)
1637 /*
1638 * This probe is an independent(and non-optimized) kprobe
1639 * (not an aggrprobe). Remove from the hash list.
1640 */
1641 goto disarmed;
1642
1643 /* Following process expects this probe is an aggrprobe */
1644 WARN_ON(!kprobe_aggrprobe(ap));
1645
1646 if (list_is_singular(&ap->list) && kprobe_disarmed(ap))
1647 /*
1648 * !disarmed could be happen if the probe is under delayed
1649 * unoptimizing.
1650 */
1651 goto disarmed;
1652 else {
1653 /* If disabling probe has special handlers, update aggrprobe */
1654 if (p->break_handler && !kprobe_gone(p))
1655 ap->break_handler = NULL;
1656 if (p->post_handler && !kprobe_gone(p)) {
1657 list_for_each_entry_rcu(list_p, &ap->list, list) {
1658 if ((list_p != p) && (list_p->post_handler))
1659 goto noclean;
1660 }
1661 ap->post_handler = NULL;
1662 }
1663noclean:
1664 /*
1665 * Remove from the aggrprobe: this path will do nothing in
1666 * __unregister_kprobe_bottom().
1667 */
1668 list_del_rcu(&p->list);
1669 if (!kprobe_disabled(ap) && !kprobes_all_disarmed)
1670 /*
1671 * Try to optimize this probe again, because post
1672 * handler may have been changed.
1673 */
1674 optimize_kprobe(ap);
1675 }
1676 return 0;
1677
1678disarmed:
1679 BUG_ON(!kprobe_disarmed(ap));
1680 hlist_del_rcu(&ap->hlist);
1681 return 0;
1682}
1683
1684static void __unregister_kprobe_bottom(struct kprobe *p)
1685{
1686 struct kprobe *ap;
1687
1688 if (list_empty(&p->list))
1689 /* This is an independent kprobe */
1690 arch_remove_kprobe(p);
1691 else if (list_is_singular(&p->list)) {
1692 /* This is the last child of an aggrprobe */
1693 ap = list_entry(p->list.next, struct kprobe, list);
1694 list_del(&p->list);
1695 free_aggr_kprobe(ap);
1696 }
1697 /* Otherwise, do nothing. */
1698}
1699
1700int register_kprobes(struct kprobe **kps, int num)
1701{
1702 int i, ret = 0;
1703
1704 if (num <= 0)
1705 return -EINVAL;
1706 for (i = 0; i < num; i++) {
1707 ret = register_kprobe(kps[i]);
1708 if (ret < 0) {
1709 if (i > 0)
1710 unregister_kprobes(kps, i);
1711 break;
1712 }
1713 }
1714 return ret;
1715}
1716EXPORT_SYMBOL_GPL(register_kprobes);
1717
1718void unregister_kprobe(struct kprobe *p)
1719{
1720 unregister_kprobes(&p, 1);
1721}
1722EXPORT_SYMBOL_GPL(unregister_kprobe);
1723
1724void unregister_kprobes(struct kprobe **kps, int num)
1725{
1726 int i;
1727
1728 if (num <= 0)
1729 return;
1730 mutex_lock(&kprobe_mutex);
1731 for (i = 0; i < num; i++)
1732 if (__unregister_kprobe_top(kps[i]) < 0)
1733 kps[i]->addr = NULL;
1734 mutex_unlock(&kprobe_mutex);
1735
1736 synchronize_sched();
1737 for (i = 0; i < num; i++)
1738 if (kps[i]->addr)
1739 __unregister_kprobe_bottom(kps[i]);
1740}
1741EXPORT_SYMBOL_GPL(unregister_kprobes);
1742
1743int __weak __kprobes kprobe_exceptions_notify(struct notifier_block *self,
1744 unsigned long val, void *data)
1745{
1746 return NOTIFY_DONE;
1747}
1748
1749static struct notifier_block kprobe_exceptions_nb = {
1750 .notifier_call = kprobe_exceptions_notify,
1751 .priority = 0x7fffffff /* we need to be notified first */
1752};
1753
1754unsigned long __weak arch_deref_entry_point(void *entry)
1755{
1756 return (unsigned long)entry;
1757}
1758
1759int register_jprobes(struct jprobe **jps, int num)
1760{
1761 struct jprobe *jp;
1762 int ret = 0, i;
1763
1764 if (num <= 0)
1765 return -EINVAL;
1766 for (i = 0; i < num; i++) {
1767 unsigned long addr, offset;
1768 jp = jps[i];
1769 addr = arch_deref_entry_point(jp->entry);
1770
1771 /* Verify probepoint is a function entry point */
1772 if (kallsyms_lookup_size_offset(addr, NULL, &offset) &&
1773 offset == 0) {
1774 jp->kp.pre_handler = setjmp_pre_handler;
1775 jp->kp.break_handler = longjmp_break_handler;
1776 ret = register_kprobe(&jp->kp);
1777 } else
1778 ret = -EINVAL;
1779
1780 if (ret < 0) {
1781 if (i > 0)
1782 unregister_jprobes(jps, i);
1783 break;
1784 }
1785 }
1786 return ret;
1787}
1788EXPORT_SYMBOL_GPL(register_jprobes);
1789
1790int register_jprobe(struct jprobe *jp)
1791{
1792 return register_jprobes(&jp, 1);
1793}
1794EXPORT_SYMBOL_GPL(register_jprobe);
1795
1796void unregister_jprobe(struct jprobe *jp)
1797{
1798 unregister_jprobes(&jp, 1);
1799}
1800EXPORT_SYMBOL_GPL(unregister_jprobe);
1801
1802void unregister_jprobes(struct jprobe **jps, int num)
1803{
1804 int i;
1805
1806 if (num <= 0)
1807 return;
1808 mutex_lock(&kprobe_mutex);
1809 for (i = 0; i < num; i++)
1810 if (__unregister_kprobe_top(&jps[i]->kp) < 0)
1811 jps[i]->kp.addr = NULL;
1812 mutex_unlock(&kprobe_mutex);
1813
1814 synchronize_sched();
1815 for (i = 0; i < num; i++) {
1816 if (jps[i]->kp.addr)
1817 __unregister_kprobe_bottom(&jps[i]->kp);
1818 }
1819}
1820EXPORT_SYMBOL_GPL(unregister_jprobes);
1821
1822#ifdef CONFIG_KRETPROBES
1823/*
1824 * This kprobe pre_handler is registered with every kretprobe. When probe
1825 * hits it will set up the return probe.
1826 */
1827static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
1828{
1829 struct kretprobe *rp = container_of(p, struct kretprobe, kp);
1830 unsigned long hash, flags = 0;
1831 struct kretprobe_instance *ri;
1832
1833 /*
1834 * To avoid deadlocks, prohibit return probing in NMI contexts,
1835 * just skip the probe and increase the (inexact) 'nmissed'
1836 * statistical counter, so that the user is informed that
1837 * something happened:
1838 */
1839 if (unlikely(in_nmi())) {
1840 rp->nmissed++;
1841 return 0;
1842 }
1843
1844 /* TODO: consider to only swap the RA after the last pre_handler fired */
1845 hash = hash_ptr(current, KPROBE_HASH_BITS);
1846 raw_spin_lock_irqsave(&rp->lock, flags);
1847 if (!hlist_empty(&rp->free_instances)) {
1848 ri = hlist_entry(rp->free_instances.first,
1849 struct kretprobe_instance, hlist);
1850 hlist_del(&ri->hlist);
1851 raw_spin_unlock_irqrestore(&rp->lock, flags);
1852
1853 ri->rp = rp;
1854 ri->task = current;
1855
1856 if (rp->entry_handler && rp->entry_handler(ri, regs)) {
1857 raw_spin_lock_irqsave(&rp->lock, flags);
1858 hlist_add_head(&ri->hlist, &rp->free_instances);
1859 raw_spin_unlock_irqrestore(&rp->lock, flags);
1860 return 0;
1861 }
1862
1863 arch_prepare_kretprobe(ri, regs);
1864
1865 /* XXX(hch): why is there no hlist_move_head? */
1866 INIT_HLIST_NODE(&ri->hlist);
1867 kretprobe_table_lock(hash, &flags);
1868 hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
1869 kretprobe_table_unlock(hash, &flags);
1870 } else {
1871 rp->nmissed++;
1872 raw_spin_unlock_irqrestore(&rp->lock, flags);
1873 }
1874 return 0;
1875}
1876NOKPROBE_SYMBOL(pre_handler_kretprobe);
1877
1878int register_kretprobe(struct kretprobe *rp)
1879{
1880 int ret = 0;
1881 struct kretprobe_instance *inst;
1882 int i;
1883 void *addr;
1884
1885 if (kretprobe_blacklist_size) {
1886 addr = kprobe_addr(&rp->kp);
1887 if (IS_ERR(addr))
1888 return PTR_ERR(addr);
1889
1890 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1891 if (kretprobe_blacklist[i].addr == addr)
1892 return -EINVAL;
1893 }
1894 }
1895
1896 rp->kp.pre_handler = pre_handler_kretprobe;
1897 rp->kp.post_handler = NULL;
1898 rp->kp.fault_handler = NULL;
1899 rp->kp.break_handler = NULL;
1900
1901 /* Pre-allocate memory for max kretprobe instances */
1902 if (rp->maxactive <= 0) {
1903#ifdef CONFIG_PREEMPT
1904 rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
1905#else
1906 rp->maxactive = num_possible_cpus();
1907#endif
1908 }
1909 raw_spin_lock_init(&rp->lock);
1910 INIT_HLIST_HEAD(&rp->free_instances);
1911 for (i = 0; i < rp->maxactive; i++) {
1912 inst = kmalloc(sizeof(struct kretprobe_instance) +
1913 rp->data_size, GFP_KERNEL);
1914 if (inst == NULL) {
1915 free_rp_inst(rp);
1916 return -ENOMEM;
1917 }
1918 INIT_HLIST_NODE(&inst->hlist);
1919 hlist_add_head(&inst->hlist, &rp->free_instances);
1920 }
1921
1922 rp->nmissed = 0;
1923 /* Establish function entry probe point */
1924 ret = register_kprobe(&rp->kp);
1925 if (ret != 0)
1926 free_rp_inst(rp);
1927 return ret;
1928}
1929EXPORT_SYMBOL_GPL(register_kretprobe);
1930
1931int register_kretprobes(struct kretprobe **rps, int num)
1932{
1933 int ret = 0, i;
1934
1935 if (num <= 0)
1936 return -EINVAL;
1937 for (i = 0; i < num; i++) {
1938 ret = register_kretprobe(rps[i]);
1939 if (ret < 0) {
1940 if (i > 0)
1941 unregister_kretprobes(rps, i);
1942 break;
1943 }
1944 }
1945 return ret;
1946}
1947EXPORT_SYMBOL_GPL(register_kretprobes);
1948
1949void unregister_kretprobe(struct kretprobe *rp)
1950{
1951 unregister_kretprobes(&rp, 1);
1952}
1953EXPORT_SYMBOL_GPL(unregister_kretprobe);
1954
1955void unregister_kretprobes(struct kretprobe **rps, int num)
1956{
1957 int i;
1958
1959 if (num <= 0)
1960 return;
1961 mutex_lock(&kprobe_mutex);
1962 for (i = 0; i < num; i++)
1963 if (__unregister_kprobe_top(&rps[i]->kp) < 0)
1964 rps[i]->kp.addr = NULL;
1965 mutex_unlock(&kprobe_mutex);
1966
1967 synchronize_sched();
1968 for (i = 0; i < num; i++) {
1969 if (rps[i]->kp.addr) {
1970 __unregister_kprobe_bottom(&rps[i]->kp);
1971 cleanup_rp_inst(rps[i]);
1972 }
1973 }
1974}
1975EXPORT_SYMBOL_GPL(unregister_kretprobes);
1976
1977#else /* CONFIG_KRETPROBES */
1978int register_kretprobe(struct kretprobe *rp)
1979{
1980 return -ENOSYS;
1981}
1982EXPORT_SYMBOL_GPL(register_kretprobe);
1983
1984int register_kretprobes(struct kretprobe **rps, int num)
1985{
1986 return -ENOSYS;
1987}
1988EXPORT_SYMBOL_GPL(register_kretprobes);
1989
1990void unregister_kretprobe(struct kretprobe *rp)
1991{
1992}
1993EXPORT_SYMBOL_GPL(unregister_kretprobe);
1994
1995void unregister_kretprobes(struct kretprobe **rps, int num)
1996{
1997}
1998EXPORT_SYMBOL_GPL(unregister_kretprobes);
1999
2000static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
2001{
2002 return 0;
2003}
2004NOKPROBE_SYMBOL(pre_handler_kretprobe);
2005
2006#endif /* CONFIG_KRETPROBES */
2007
2008/* Set the kprobe gone and remove its instruction buffer. */
2009static void kill_kprobe(struct kprobe *p)
2010{
2011 struct kprobe *kp;
2012
2013 p->flags |= KPROBE_FLAG_GONE;
2014 if (kprobe_aggrprobe(p)) {
2015 /*
2016 * If this is an aggr_kprobe, we have to list all the
2017 * chained probes and mark them GONE.
2018 */
2019 list_for_each_entry_rcu(kp, &p->list, list)
2020 kp->flags |= KPROBE_FLAG_GONE;
2021 p->post_handler = NULL;
2022 p->break_handler = NULL;
2023 kill_optimized_kprobe(p);
2024 }
2025 /*
2026 * Here, we can remove insn_slot safely, because no thread calls
2027 * the original probed function (which will be freed soon) any more.
2028 */
2029 arch_remove_kprobe(p);
2030}
2031
2032/* Disable one kprobe */
2033int disable_kprobe(struct kprobe *kp)
2034{
2035 int ret = 0;
2036
2037 mutex_lock(&kprobe_mutex);
2038
2039 /* Disable this kprobe */
2040 if (__disable_kprobe(kp) == NULL)
2041 ret = -EINVAL;
2042
2043 mutex_unlock(&kprobe_mutex);
2044 return ret;
2045}
2046EXPORT_SYMBOL_GPL(disable_kprobe);
2047
2048/* Enable one kprobe */
2049int enable_kprobe(struct kprobe *kp)
2050{
2051 int ret = 0;
2052 struct kprobe *p;
2053
2054 mutex_lock(&kprobe_mutex);
2055
2056 /* Check whether specified probe is valid. */
2057 p = __get_valid_kprobe(kp);
2058 if (unlikely(p == NULL)) {
2059 ret = -EINVAL;
2060 goto out;
2061 }
2062
2063 if (kprobe_gone(kp)) {
2064 /* This kprobe has gone, we couldn't enable it. */
2065 ret = -EINVAL;
2066 goto out;
2067 }
2068
2069 if (p != kp)
2070 kp->flags &= ~KPROBE_FLAG_DISABLED;
2071
2072 if (!kprobes_all_disarmed && kprobe_disabled(p)) {
2073 p->flags &= ~KPROBE_FLAG_DISABLED;
2074 arm_kprobe(p);
2075 }
2076out:
2077 mutex_unlock(&kprobe_mutex);
2078 return ret;
2079}
2080EXPORT_SYMBOL_GPL(enable_kprobe);
2081
2082void dump_kprobe(struct kprobe *kp)
2083{
2084 printk(KERN_WARNING "Dumping kprobe:\n");
2085 printk(KERN_WARNING "Name: %s\nAddress: %p\nOffset: %x\n",
2086 kp->symbol_name, kp->addr, kp->offset);
2087}
2088NOKPROBE_SYMBOL(dump_kprobe);
2089
2090/*
2091 * Lookup and populate the kprobe_blacklist.
2092 *
2093 * Unlike the kretprobe blacklist, we'll need to determine
2094 * the range of addresses that belong to the said functions,
2095 * since a kprobe need not necessarily be at the beginning
2096 * of a function.
2097 */
2098static int __init populate_kprobe_blacklist(unsigned long *start,
2099 unsigned long *end)
2100{
2101 unsigned long *iter;
2102 struct kprobe_blacklist_entry *ent;
2103 unsigned long entry, offset = 0, size = 0;
2104
2105 for (iter = start; iter < end; iter++) {
2106 entry = arch_deref_entry_point((void *)*iter);
2107
2108 if (!kernel_text_address(entry) ||
2109 !kallsyms_lookup_size_offset(entry, &size, &offset)) {
2110 pr_err("Failed to find blacklist at %p\n",
2111 (void *)entry);
2112 continue;
2113 }
2114
2115 ent = kmalloc(sizeof(*ent), GFP_KERNEL);
2116 if (!ent)
2117 return -ENOMEM;
2118 ent->start_addr = entry;
2119 ent->end_addr = entry + size;
2120 INIT_LIST_HEAD(&ent->list);
2121 list_add_tail(&ent->list, &kprobe_blacklist);
2122 }
2123 return 0;
2124}
2125
2126/* Module notifier call back, checking kprobes on the module */
2127static int kprobes_module_callback(struct notifier_block *nb,
2128 unsigned long val, void *data)
2129{
2130 struct module *mod = data;
2131 struct hlist_head *head;
2132 struct kprobe *p;
2133 unsigned int i;
2134 int checkcore = (val == MODULE_STATE_GOING);
2135
2136 if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
2137 return NOTIFY_DONE;
2138
2139 /*
2140 * When MODULE_STATE_GOING was notified, both of module .text and
2141 * .init.text sections would be freed. When MODULE_STATE_LIVE was
2142 * notified, only .init.text section would be freed. We need to
2143 * disable kprobes which have been inserted in the sections.
2144 */
2145 mutex_lock(&kprobe_mutex);
2146 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2147 head = &kprobe_table[i];
2148 hlist_for_each_entry_rcu(p, head, hlist)
2149 if (within_module_init((unsigned long)p->addr, mod) ||
2150 (checkcore &&
2151 within_module_core((unsigned long)p->addr, mod))) {
2152 /*
2153 * The vaddr this probe is installed will soon
2154 * be vfreed buy not synced to disk. Hence,
2155 * disarming the breakpoint isn't needed.
2156 */
2157 kill_kprobe(p);
2158 }
2159 }
2160 mutex_unlock(&kprobe_mutex);
2161 return NOTIFY_DONE;
2162}
2163
2164static struct notifier_block kprobe_module_nb = {
2165 .notifier_call = kprobes_module_callback,
2166 .priority = 0
2167};
2168
2169/* Markers of _kprobe_blacklist section */
2170extern unsigned long __start_kprobe_blacklist[];
2171extern unsigned long __stop_kprobe_blacklist[];
2172
2173static int __init init_kprobes(void)
2174{
2175 int i, err = 0;
2176
2177 /* FIXME allocate the probe table, currently defined statically */
2178 /* initialize all list heads */
2179 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2180 INIT_HLIST_HEAD(&kprobe_table[i]);
2181 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
2182 raw_spin_lock_init(&(kretprobe_table_locks[i].lock));
2183 }
2184
2185 err = populate_kprobe_blacklist(__start_kprobe_blacklist,
2186 __stop_kprobe_blacklist);
2187 if (err) {
2188 pr_err("kprobes: failed to populate blacklist: %d\n", err);
2189 pr_err("Please take care of using kprobes.\n");
2190 }
2191
2192 if (kretprobe_blacklist_size) {
2193 /* lookup the function address from its name */
2194 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
2195 kprobe_lookup_name(kretprobe_blacklist[i].name,
2196 kretprobe_blacklist[i].addr);
2197 if (!kretprobe_blacklist[i].addr)
2198 printk("kretprobe: lookup failed: %s\n",
2199 kretprobe_blacklist[i].name);
2200 }
2201 }
2202
2203#if defined(CONFIG_OPTPROBES)
2204#if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
2205 /* Init kprobe_optinsn_slots */
2206 kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
2207#endif
2208 /* By default, kprobes can be optimized */
2209 kprobes_allow_optimization = true;
2210#endif
2211
2212 /* By default, kprobes are armed */
2213 kprobes_all_disarmed = false;
2214
2215 err = arch_init_kprobes();
2216 if (!err)
2217 err = register_die_notifier(&kprobe_exceptions_nb);
2218 if (!err)
2219 err = register_module_notifier(&kprobe_module_nb);
2220
2221 kprobes_initialized = (err == 0);
2222
2223 if (!err)
2224 init_test_probes();
2225 return err;
2226}
2227
2228#ifdef CONFIG_DEBUG_FS
2229static void report_probe(struct seq_file *pi, struct kprobe *p,
2230 const char *sym, int offset, char *modname, struct kprobe *pp)
2231{
2232 char *kprobe_type;
2233
2234 if (p->pre_handler == pre_handler_kretprobe)
2235 kprobe_type = "r";
2236 else if (p->pre_handler == setjmp_pre_handler)
2237 kprobe_type = "j";
2238 else
2239 kprobe_type = "k";
2240
2241 if (sym)
2242 seq_printf(pi, "%p %s %s+0x%x %s ",
2243 p->addr, kprobe_type, sym, offset,
2244 (modname ? modname : " "));
2245 else
2246 seq_printf(pi, "%p %s %p ",
2247 p->addr, kprobe_type, p->addr);
2248
2249 if (!pp)
2250 pp = p;
2251 seq_printf(pi, "%s%s%s%s\n",
2252 (kprobe_gone(p) ? "[GONE]" : ""),
2253 ((kprobe_disabled(p) && !kprobe_gone(p)) ? "[DISABLED]" : ""),
2254 (kprobe_optimized(pp) ? "[OPTIMIZED]" : ""),
2255 (kprobe_ftrace(pp) ? "[FTRACE]" : ""));
2256}
2257
2258static void *kprobe_seq_start(struct seq_file *f, loff_t *pos)
2259{
2260 return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
2261}
2262
2263static void *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
2264{
2265 (*pos)++;
2266 if (*pos >= KPROBE_TABLE_SIZE)
2267 return NULL;
2268 return pos;
2269}
2270
2271static void kprobe_seq_stop(struct seq_file *f, void *v)
2272{
2273 /* Nothing to do */
2274}
2275
2276static int show_kprobe_addr(struct seq_file *pi, void *v)
2277{
2278 struct hlist_head *head;
2279 struct kprobe *p, *kp;
2280 const char *sym = NULL;
2281 unsigned int i = *(loff_t *) v;
2282 unsigned long offset = 0;
2283 char *modname, namebuf[KSYM_NAME_LEN];
2284
2285 head = &kprobe_table[i];
2286 preempt_disable();
2287 hlist_for_each_entry_rcu(p, head, hlist) {
2288 sym = kallsyms_lookup((unsigned long)p->addr, NULL,
2289 &offset, &modname, namebuf);
2290 if (kprobe_aggrprobe(p)) {
2291 list_for_each_entry_rcu(kp, &p->list, list)
2292 report_probe(pi, kp, sym, offset, modname, p);
2293 } else
2294 report_probe(pi, p, sym, offset, modname, NULL);
2295 }
2296 preempt_enable();
2297 return 0;
2298}
2299
2300static const struct seq_operations kprobes_seq_ops = {
2301 .start = kprobe_seq_start,
2302 .next = kprobe_seq_next,
2303 .stop = kprobe_seq_stop,
2304 .show = show_kprobe_addr
2305};
2306
2307static int kprobes_open(struct inode *inode, struct file *filp)
2308{
2309 return seq_open(filp, &kprobes_seq_ops);
2310}
2311
2312static const struct file_operations debugfs_kprobes_operations = {
2313 .open = kprobes_open,
2314 .read = seq_read,
2315 .llseek = seq_lseek,
2316 .release = seq_release,
2317};
2318
2319/* kprobes/blacklist -- shows which functions can not be probed */
2320static void *kprobe_blacklist_seq_start(struct seq_file *m, loff_t *pos)
2321{
2322 return seq_list_start(&kprobe_blacklist, *pos);
2323}
2324
2325static void *kprobe_blacklist_seq_next(struct seq_file *m, void *v, loff_t *pos)
2326{
2327 return seq_list_next(v, &kprobe_blacklist, pos);
2328}
2329
2330static int kprobe_blacklist_seq_show(struct seq_file *m, void *v)
2331{
2332 struct kprobe_blacklist_entry *ent =
2333 list_entry(v, struct kprobe_blacklist_entry, list);
2334
2335 seq_printf(m, "0x%p-0x%p\t%ps\n", (void *)ent->start_addr,
2336 (void *)ent->end_addr, (void *)ent->start_addr);
2337 return 0;
2338}
2339
2340static const struct seq_operations kprobe_blacklist_seq_ops = {
2341 .start = kprobe_blacklist_seq_start,
2342 .next = kprobe_blacklist_seq_next,
2343 .stop = kprobe_seq_stop, /* Reuse void function */
2344 .show = kprobe_blacklist_seq_show,
2345};
2346
2347static int kprobe_blacklist_open(struct inode *inode, struct file *filp)
2348{
2349 return seq_open(filp, &kprobe_blacklist_seq_ops);
2350}
2351
2352static const struct file_operations debugfs_kprobe_blacklist_ops = {
2353 .open = kprobe_blacklist_open,
2354 .read = seq_read,
2355 .llseek = seq_lseek,
2356 .release = seq_release,
2357};
2358
2359static void arm_all_kprobes(void)
2360{
2361 struct hlist_head *head;
2362 struct kprobe *p;
2363 unsigned int i;
2364
2365 mutex_lock(&kprobe_mutex);
2366
2367 /* If kprobes are armed, just return */
2368 if (!kprobes_all_disarmed)
2369 goto already_enabled;
2370
2371 /*
2372 * optimize_kprobe() called by arm_kprobe() checks
2373 * kprobes_all_disarmed, so set kprobes_all_disarmed before
2374 * arm_kprobe.
2375 */
2376 kprobes_all_disarmed = false;
2377 /* Arming kprobes doesn't optimize kprobe itself */
2378 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2379 head = &kprobe_table[i];
2380 hlist_for_each_entry_rcu(p, head, hlist)
2381 if (!kprobe_disabled(p))
2382 arm_kprobe(p);
2383 }
2384
2385 printk(KERN_INFO "Kprobes globally enabled\n");
2386
2387already_enabled:
2388 mutex_unlock(&kprobe_mutex);
2389 return;
2390}
2391
2392static void disarm_all_kprobes(void)
2393{
2394 struct hlist_head *head;
2395 struct kprobe *p;
2396 unsigned int i;
2397
2398 mutex_lock(&kprobe_mutex);
2399
2400 /* If kprobes are already disarmed, just return */
2401 if (kprobes_all_disarmed) {
2402 mutex_unlock(&kprobe_mutex);
2403 return;
2404 }
2405
2406 kprobes_all_disarmed = true;
2407 printk(KERN_INFO "Kprobes globally disabled\n");
2408
2409 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2410 head = &kprobe_table[i];
2411 hlist_for_each_entry_rcu(p, head, hlist) {
2412 if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
2413 disarm_kprobe(p, false);
2414 }
2415 }
2416 mutex_unlock(&kprobe_mutex);
2417
2418 /* Wait for disarming all kprobes by optimizer */
2419 wait_for_kprobe_optimizer();
2420}
2421
2422/*
2423 * XXX: The debugfs bool file interface doesn't allow for callbacks
2424 * when the bool state is switched. We can reuse that facility when
2425 * available
2426 */
2427static ssize_t read_enabled_file_bool(struct file *file,
2428 char __user *user_buf, size_t count, loff_t *ppos)
2429{
2430 char buf[3];
2431
2432 if (!kprobes_all_disarmed)
2433 buf[0] = '1';
2434 else
2435 buf[0] = '0';
2436 buf[1] = '\n';
2437 buf[2] = 0x00;
2438 return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
2439}
2440
2441static ssize_t write_enabled_file_bool(struct file *file,
2442 const char __user *user_buf, size_t count, loff_t *ppos)
2443{
2444 char buf[32];
2445 size_t buf_size;
2446
2447 buf_size = min(count, (sizeof(buf)-1));
2448 if (copy_from_user(buf, user_buf, buf_size))
2449 return -EFAULT;
2450
2451 buf[buf_size] = '\0';
2452 switch (buf[0]) {
2453 case 'y':
2454 case 'Y':
2455 case '1':
2456 arm_all_kprobes();
2457 break;
2458 case 'n':
2459 case 'N':
2460 case '0':
2461 disarm_all_kprobes();
2462 break;
2463 default:
2464 return -EINVAL;
2465 }
2466
2467 return count;
2468}
2469
2470static const struct file_operations fops_kp = {
2471 .read = read_enabled_file_bool,
2472 .write = write_enabled_file_bool,
2473 .llseek = default_llseek,
2474};
2475
2476static int __init debugfs_kprobe_init(void)
2477{
2478 struct dentry *dir, *file;
2479 unsigned int value = 1;
2480
2481 dir = debugfs_create_dir("kprobes", NULL);
2482 if (!dir)
2483 return -ENOMEM;
2484
2485 file = debugfs_create_file("list", 0444, dir, NULL,
2486 &debugfs_kprobes_operations);
2487 if (!file)
2488 goto error;
2489
2490 file = debugfs_create_file("enabled", 0600, dir,
2491 &value, &fops_kp);
2492 if (!file)
2493 goto error;
2494
2495 file = debugfs_create_file("blacklist", 0444, dir, NULL,
2496 &debugfs_kprobe_blacklist_ops);
2497 if (!file)
2498 goto error;
2499
2500 return 0;
2501
2502error:
2503 debugfs_remove(dir);
2504 return -ENOMEM;
2505}
2506
2507late_initcall(debugfs_kprobe_init);
2508#endif /* CONFIG_DEBUG_FS */
2509
2510module_init(init_kprobes);
2511
2512/* defined in arch/.../kernel/kprobes.c */
2513EXPORT_SYMBOL_GPL(jprobe_return);