2 * Kernel Probes (KProbes)
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.
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.
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.
19 * Copyright (C) IBM Corporation, 2002, 2004
21 * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
22 * Probes initial implementation (includes suggestions from
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.
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>
52 #include <asm-generic/sections.h>
53 #include <asm/cacheflush.h>
54 #include <asm/errno.h>
55 #include <asm/uaccess.h>
57 #define KPROBE_HASH_BITS 6
58 #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
62 * Some oddball architectures like 64bit powerpc have function descriptors
63 * so this must be overridable.
65 #ifndef kprobe_lookup_name
66 #define kprobe_lookup_name(name, addr) \
67 addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name)))
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
];
74 /* NOTE: change this value only with kprobe_mutex held */
75 static bool kprobes_all_disarmed
;
77 /* This protects kprobe_table and optimizing_list */
78 static DEFINE_MUTEX(kprobe_mutex
);
79 static DEFINE_PER_CPU(struct kprobe
*, kprobe_instance
) = NULL
;
81 raw_spinlock_t lock ____cacheline_aligned_in_smp
;
82 } kretprobe_table_locks
[KPROBE_TABLE_SIZE
];
84 static raw_spinlock_t
*kretprobe_table_lock_ptr(unsigned long hash
)
86 return &(kretprobe_table_locks
[hash
].lock
);
90 * Normally, functions that we'd want to prohibit kprobes in, are marked
91 * __kprobes. But, there are cases where such functions already belong to
92 * a different section (__sched for preempt_schedule)
94 * For such cases, we now have a blacklist
96 static struct kprobe_blackpoint kprobe_blacklist
[] = {
97 {"preempt_schedule",},
98 {"native_get_debugreg",},
99 {"irq_entries_start",},
100 {"common_interrupt",},
101 {"mcount",}, /* mcount can be called from everywhere */
102 {NULL
} /* Terminator */
105 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
107 * kprobe->ainsn.insn points to the copy of the instruction to be
108 * single-stepped. x86_64, POWER4 and above have no-exec support and
109 * stepping on the instruction on a vmalloced/kmalloced/data page
110 * is a recipe for disaster
112 struct kprobe_insn_page
{
113 struct list_head list
;
114 kprobe_opcode_t
*insns
; /* Page of instruction slots */
120 #define KPROBE_INSN_PAGE_SIZE(slots) \
121 (offsetof(struct kprobe_insn_page, slot_used) + \
122 (sizeof(char) * (slots)))
124 static int slots_per_page(struct kprobe_insn_cache
*c
)
126 return PAGE_SIZE
/(c
->insn_size
* sizeof(kprobe_opcode_t
));
129 enum kprobe_slot_state
{
135 struct kprobe_insn_cache kprobe_insn_slots
= {
136 .mutex
= __MUTEX_INITIALIZER(kprobe_insn_slots
.mutex
),
137 .pages
= LIST_HEAD_INIT(kprobe_insn_slots
.pages
),
138 .insn_size
= MAX_INSN_SIZE
,
141 static int __kprobes
collect_garbage_slots(struct kprobe_insn_cache
*c
);
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.
147 kprobe_opcode_t __kprobes
*__get_insn_slot(struct kprobe_insn_cache
*c
)
149 struct kprobe_insn_page
*kip
;
150 kprobe_opcode_t
*slot
= NULL
;
152 mutex_lock(&c
->mutex
);
154 list_for_each_entry(kip
, &c
->pages
, list
) {
155 if (kip
->nused
< slots_per_page(c
)) {
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
;
161 slot
= kip
->insns
+ (i
* c
->insn_size
);
165 /* kip->nused is broken. Fix it. */
166 kip
->nused
= slots_per_page(c
);
171 /* If there are any garbage slots, collect it and try again. */
172 if (c
->nr_garbage
&& collect_garbage_slots(c
) == 0)
175 /* All out of space. Need to allocate a new page. */
176 kip
= kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c
)), GFP_KERNEL
);
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.
185 kip
->insns
= module_alloc(PAGE_SIZE
);
190 INIT_LIST_HEAD(&kip
->list
);
191 memset(kip
->slot_used
, SLOT_CLEAN
, slots_per_page(c
));
192 kip
->slot_used
[0] = SLOT_USED
;
195 list_add(&kip
->list
, &c
->pages
);
198 mutex_unlock(&c
->mutex
);
202 /* Return 1 if all garbages are collected, otherwise 0. */
203 static int __kprobes
collect_one_slot(struct kprobe_insn_page
*kip
, int idx
)
205 kip
->slot_used
[idx
] = SLOT_CLEAN
;
207 if (kip
->nused
== 0) {
209 * Page is no longer in use. Free it unless
210 * it's the last one. We keep the last one
211 * so as not to have to set it up again the
212 * next time somebody inserts a probe.
214 if (!list_is_singular(&kip
->list
)) {
215 list_del(&kip
->list
);
216 module_free(NULL
, kip
->insns
);
224 static int __kprobes
collect_garbage_slots(struct kprobe_insn_cache
*c
)
226 struct kprobe_insn_page
*kip
, *next
;
228 /* Ensure no-one is interrupted on the garbages */
231 list_for_each_entry_safe(kip
, next
, &c
->pages
, list
) {
233 if (kip
->ngarbage
== 0)
235 kip
->ngarbage
= 0; /* we will collect all garbages */
236 for (i
= 0; i
< slots_per_page(c
); i
++) {
237 if (kip
->slot_used
[i
] == SLOT_DIRTY
&&
238 collect_one_slot(kip
, i
))
246 void __kprobes
__free_insn_slot(struct kprobe_insn_cache
*c
,
247 kprobe_opcode_t
*slot
, int dirty
)
249 struct kprobe_insn_page
*kip
;
251 mutex_lock(&c
->mutex
);
252 list_for_each_entry(kip
, &c
->pages
, list
) {
253 long idx
= ((long)slot
- (long)kip
->insns
) /
254 (c
->insn_size
* sizeof(kprobe_opcode_t
));
255 if (idx
>= 0 && idx
< slots_per_page(c
)) {
256 WARN_ON(kip
->slot_used
[idx
] != SLOT_USED
);
258 kip
->slot_used
[idx
] = SLOT_DIRTY
;
260 if (++c
->nr_garbage
> slots_per_page(c
))
261 collect_garbage_slots(c
);
263 collect_one_slot(kip
, idx
);
267 /* Could not free this slot. */
270 mutex_unlock(&c
->mutex
);
273 #ifdef CONFIG_OPTPROBES
274 /* For optimized_kprobe buffer */
275 struct kprobe_insn_cache kprobe_optinsn_slots
= {
276 .mutex
= __MUTEX_INITIALIZER(kprobe_optinsn_slots
.mutex
),
277 .pages
= LIST_HEAD_INIT(kprobe_optinsn_slots
.pages
),
278 /* .insn_size is initialized later */
284 /* We have preemption disabled.. so it is safe to use __ versions */
285 static inline void set_kprobe_instance(struct kprobe
*kp
)
287 __this_cpu_write(kprobe_instance
, kp
);
290 static inline void reset_kprobe_instance(void)
292 __this_cpu_write(kprobe_instance
, NULL
);
296 * This routine is called either:
297 * - under the kprobe_mutex - during kprobe_[un]register()
299 * - with preemption disabled - from arch/xxx/kernel/kprobes.c
301 struct kprobe __kprobes
*get_kprobe(void *addr
)
303 struct hlist_head
*head
;
306 head
= &kprobe_table
[hash_ptr(addr
, KPROBE_HASH_BITS
)];
307 hlist_for_each_entry_rcu(p
, head
, hlist
) {
315 static int __kprobes
aggr_pre_handler(struct kprobe
*p
, struct pt_regs
*regs
);
317 /* Return true if the kprobe is an aggregator */
318 static inline int kprobe_aggrprobe(struct kprobe
*p
)
320 return p
->pre_handler
== aggr_pre_handler
;
323 /* Return true(!0) if the kprobe is unused */
324 static inline int kprobe_unused(struct kprobe
*p
)
326 return kprobe_aggrprobe(p
) && kprobe_disabled(p
) &&
327 list_empty(&p
->list
);
331 * Keep all fields in the kprobe consistent
333 static inline void copy_kprobe(struct kprobe
*ap
, struct kprobe
*p
)
335 memcpy(&p
->opcode
, &ap
->opcode
, sizeof(kprobe_opcode_t
));
336 memcpy(&p
->ainsn
, &ap
->ainsn
, sizeof(struct arch_specific_insn
));
339 #ifdef CONFIG_OPTPROBES
340 /* NOTE: change this value only with kprobe_mutex held */
341 static bool kprobes_allow_optimization
;
344 * Call all pre_handler on the list, but ignores its return value.
345 * This must be called from arch-dep optimized caller.
347 void __kprobes
opt_pre_handler(struct kprobe
*p
, struct pt_regs
*regs
)
351 list_for_each_entry_rcu(kp
, &p
->list
, list
) {
352 if (kp
->pre_handler
&& likely(!kprobe_disabled(kp
))) {
353 set_kprobe_instance(kp
);
354 kp
->pre_handler(kp
, regs
);
356 reset_kprobe_instance();
360 /* Free optimized instructions and optimized_kprobe */
361 static __kprobes
void free_aggr_kprobe(struct kprobe
*p
)
363 struct optimized_kprobe
*op
;
365 op
= container_of(p
, struct optimized_kprobe
, kp
);
366 arch_remove_optimized_kprobe(op
);
367 arch_remove_kprobe(p
);
371 /* Return true(!0) if the kprobe is ready for optimization. */
372 static inline int kprobe_optready(struct kprobe
*p
)
374 struct optimized_kprobe
*op
;
376 if (kprobe_aggrprobe(p
)) {
377 op
= container_of(p
, struct optimized_kprobe
, kp
);
378 return arch_prepared_optinsn(&op
->optinsn
);
384 /* Return true(!0) if the kprobe is disarmed. Note: p must be on hash list */
385 static inline int kprobe_disarmed(struct kprobe
*p
)
387 struct optimized_kprobe
*op
;
389 /* If kprobe is not aggr/opt probe, just return kprobe is disabled */
390 if (!kprobe_aggrprobe(p
))
391 return kprobe_disabled(p
);
393 op
= container_of(p
, struct optimized_kprobe
, kp
);
395 return kprobe_disabled(p
) && list_empty(&op
->list
);
398 /* Return true(!0) if the probe is queued on (un)optimizing lists */
399 static int __kprobes
kprobe_queued(struct kprobe
*p
)
401 struct optimized_kprobe
*op
;
403 if (kprobe_aggrprobe(p
)) {
404 op
= container_of(p
, struct optimized_kprobe
, kp
);
405 if (!list_empty(&op
->list
))
412 * Return an optimized kprobe whose optimizing code replaces
413 * instructions including addr (exclude breakpoint).
415 static struct kprobe
*__kprobes
get_optimized_kprobe(unsigned long addr
)
418 struct kprobe
*p
= NULL
;
419 struct optimized_kprobe
*op
;
421 /* Don't check i == 0, since that is a breakpoint case. */
422 for (i
= 1; !p
&& i
< MAX_OPTIMIZED_LENGTH
; i
++)
423 p
= get_kprobe((void *)(addr
- i
));
425 if (p
&& kprobe_optready(p
)) {
426 op
= container_of(p
, struct optimized_kprobe
, kp
);
427 if (arch_within_optimized_kprobe(op
, addr
))
434 /* Optimization staging list, protected by kprobe_mutex */
435 static LIST_HEAD(optimizing_list
);
436 static LIST_HEAD(unoptimizing_list
);
437 static LIST_HEAD(freeing_list
);
439 static void kprobe_optimizer(struct work_struct
*work
);
440 static DECLARE_DELAYED_WORK(optimizing_work
, kprobe_optimizer
);
441 #define OPTIMIZE_DELAY 5
444 * Optimize (replace a breakpoint with a jump) kprobes listed on
447 static __kprobes
void do_optimize_kprobes(void)
449 /* Optimization never be done when disarmed */
450 if (kprobes_all_disarmed
|| !kprobes_allow_optimization
||
451 list_empty(&optimizing_list
))
455 * The optimization/unoptimization refers online_cpus via
456 * stop_machine() and cpu-hotplug modifies online_cpus.
457 * And same time, text_mutex will be held in cpu-hotplug and here.
458 * This combination can cause a deadlock (cpu-hotplug try to lock
459 * text_mutex but stop_machine can not be done because online_cpus
461 * To avoid this deadlock, we need to call get_online_cpus()
462 * for preventing cpu-hotplug outside of text_mutex locking.
465 mutex_lock(&text_mutex
);
466 arch_optimize_kprobes(&optimizing_list
);
467 mutex_unlock(&text_mutex
);
472 * Unoptimize (replace a jump with a breakpoint and remove the breakpoint
473 * if need) kprobes listed on unoptimizing_list.
475 static __kprobes
void do_unoptimize_kprobes(void)
477 struct optimized_kprobe
*op
, *tmp
;
479 /* Unoptimization must be done anytime */
480 if (list_empty(&unoptimizing_list
))
483 /* Ditto to do_optimize_kprobes */
485 mutex_lock(&text_mutex
);
486 arch_unoptimize_kprobes(&unoptimizing_list
, &freeing_list
);
487 /* Loop free_list for disarming */
488 list_for_each_entry_safe(op
, tmp
, &freeing_list
, list
) {
489 /* Disarm probes if marked disabled */
490 if (kprobe_disabled(&op
->kp
))
491 arch_disarm_kprobe(&op
->kp
);
492 if (kprobe_unused(&op
->kp
)) {
494 * Remove unused probes from hash list. After waiting
495 * for synchronization, these probes are reclaimed.
496 * (reclaiming is done by do_free_cleaned_kprobes.)
498 hlist_del_rcu(&op
->kp
.hlist
);
500 list_del_init(&op
->list
);
502 mutex_unlock(&text_mutex
);
506 /* Reclaim all kprobes on the free_list */
507 static __kprobes
void do_free_cleaned_kprobes(void)
509 struct optimized_kprobe
*op
, *tmp
;
511 list_for_each_entry_safe(op
, tmp
, &freeing_list
, list
) {
512 BUG_ON(!kprobe_unused(&op
->kp
));
513 list_del_init(&op
->list
);
514 free_aggr_kprobe(&op
->kp
);
518 /* Start optimizer after OPTIMIZE_DELAY passed */
519 static __kprobes
void kick_kprobe_optimizer(void)
521 schedule_delayed_work(&optimizing_work
, OPTIMIZE_DELAY
);
524 /* Kprobe jump optimizer */
525 static __kprobes
void kprobe_optimizer(struct work_struct
*work
)
527 mutex_lock(&kprobe_mutex
);
528 /* Lock modules while optimizing kprobes */
529 mutex_lock(&module_mutex
);
532 * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
533 * kprobes before waiting for quiesence period.
535 do_unoptimize_kprobes();
538 * Step 2: Wait for quiesence period to ensure all running interrupts
539 * are done. Because optprobe may modify multiple instructions
540 * there is a chance that Nth instruction is interrupted. In that
541 * case, running interrupt can return to 2nd-Nth byte of jump
542 * instruction. This wait is for avoiding it.
546 /* Step 3: Optimize kprobes after quiesence period */
547 do_optimize_kprobes();
549 /* Step 4: Free cleaned kprobes after quiesence period */
550 do_free_cleaned_kprobes();
552 mutex_unlock(&module_mutex
);
553 mutex_unlock(&kprobe_mutex
);
555 /* Step 5: Kick optimizer again if needed */
556 if (!list_empty(&optimizing_list
) || !list_empty(&unoptimizing_list
))
557 kick_kprobe_optimizer();
560 /* Wait for completing optimization and unoptimization */
561 static __kprobes
void wait_for_kprobe_optimizer(void)
563 mutex_lock(&kprobe_mutex
);
565 while (!list_empty(&optimizing_list
) || !list_empty(&unoptimizing_list
)) {
566 mutex_unlock(&kprobe_mutex
);
568 /* this will also make optimizing_work execute immmediately */
569 flush_delayed_work(&optimizing_work
);
570 /* @optimizing_work might not have been queued yet, relax */
573 mutex_lock(&kprobe_mutex
);
576 mutex_unlock(&kprobe_mutex
);
579 /* Optimize kprobe if p is ready to be optimized */
580 static __kprobes
void optimize_kprobe(struct kprobe
*p
)
582 struct optimized_kprobe
*op
;
584 /* Check if the kprobe is disabled or not ready for optimization. */
585 if (!kprobe_optready(p
) || !kprobes_allow_optimization
||
586 (kprobe_disabled(p
) || kprobes_all_disarmed
))
589 /* Both of break_handler and post_handler are not supported. */
590 if (p
->break_handler
|| p
->post_handler
)
593 op
= container_of(p
, struct optimized_kprobe
, kp
);
595 /* Check there is no other kprobes at the optimized instructions */
596 if (arch_check_optimized_kprobe(op
) < 0)
599 /* Check if it is already optimized. */
600 if (op
->kp
.flags
& KPROBE_FLAG_OPTIMIZED
)
602 op
->kp
.flags
|= KPROBE_FLAG_OPTIMIZED
;
604 if (!list_empty(&op
->list
))
605 /* This is under unoptimizing. Just dequeue the probe */
606 list_del_init(&op
->list
);
608 list_add(&op
->list
, &optimizing_list
);
609 kick_kprobe_optimizer();
613 /* Short cut to direct unoptimizing */
614 static __kprobes
void force_unoptimize_kprobe(struct optimized_kprobe
*op
)
617 arch_unoptimize_kprobe(op
);
619 if (kprobe_disabled(&op
->kp
))
620 arch_disarm_kprobe(&op
->kp
);
623 /* Unoptimize a kprobe if p is optimized */
624 static __kprobes
void unoptimize_kprobe(struct kprobe
*p
, bool force
)
626 struct optimized_kprobe
*op
;
628 if (!kprobe_aggrprobe(p
) || kprobe_disarmed(p
))
629 return; /* This is not an optprobe nor optimized */
631 op
= container_of(p
, struct optimized_kprobe
, kp
);
632 if (!kprobe_optimized(p
)) {
633 /* Unoptimized or unoptimizing case */
634 if (force
&& !list_empty(&op
->list
)) {
636 * Only if this is unoptimizing kprobe and forced,
637 * forcibly unoptimize it. (No need to unoptimize
638 * unoptimized kprobe again :)
640 list_del_init(&op
->list
);
641 force_unoptimize_kprobe(op
);
646 op
->kp
.flags
&= ~KPROBE_FLAG_OPTIMIZED
;
647 if (!list_empty(&op
->list
)) {
648 /* Dequeue from the optimization queue */
649 list_del_init(&op
->list
);
652 /* Optimized kprobe case */
654 /* Forcibly update the code: this is a special case */
655 force_unoptimize_kprobe(op
);
657 list_add(&op
->list
, &unoptimizing_list
);
658 kick_kprobe_optimizer();
662 /* Cancel unoptimizing for reusing */
663 static void reuse_unused_kprobe(struct kprobe
*ap
)
665 struct optimized_kprobe
*op
;
667 BUG_ON(!kprobe_unused(ap
));
669 * Unused kprobe MUST be on the way of delayed unoptimizing (means
670 * there is still a relative jump) and disabled.
672 op
= container_of(ap
, struct optimized_kprobe
, kp
);
673 if (unlikely(list_empty(&op
->list
)))
674 printk(KERN_WARNING
"Warning: found a stray unused "
675 "aggrprobe@%p\n", ap
->addr
);
676 /* Enable the probe again */
677 ap
->flags
&= ~KPROBE_FLAG_DISABLED
;
678 /* Optimize it again (remove from op->list) */
679 BUG_ON(!kprobe_optready(ap
));
683 /* Remove optimized instructions */
684 static void __kprobes
kill_optimized_kprobe(struct kprobe
*p
)
686 struct optimized_kprobe
*op
;
688 op
= container_of(p
, struct optimized_kprobe
, kp
);
689 if (!list_empty(&op
->list
))
690 /* Dequeue from the (un)optimization queue */
691 list_del_init(&op
->list
);
692 op
->kp
.flags
&= ~KPROBE_FLAG_OPTIMIZED
;
694 if (kprobe_unused(p
)) {
695 /* Enqueue if it is unused */
696 list_add(&op
->list
, &freeing_list
);
698 * Remove unused probes from the hash list. After waiting
699 * for synchronization, this probe is reclaimed.
700 * (reclaiming is done by do_free_cleaned_kprobes().)
702 hlist_del_rcu(&op
->kp
.hlist
);
705 /* Don't touch the code, because it is already freed. */
706 arch_remove_optimized_kprobe(op
);
709 /* Try to prepare optimized instructions */
710 static __kprobes
void prepare_optimized_kprobe(struct kprobe
*p
)
712 struct optimized_kprobe
*op
;
714 op
= container_of(p
, struct optimized_kprobe
, kp
);
715 arch_prepare_optimized_kprobe(op
);
718 /* Allocate new optimized_kprobe and try to prepare optimized instructions */
719 static __kprobes
struct kprobe
*alloc_aggr_kprobe(struct kprobe
*p
)
721 struct optimized_kprobe
*op
;
723 op
= kzalloc(sizeof(struct optimized_kprobe
), GFP_KERNEL
);
727 INIT_LIST_HEAD(&op
->list
);
728 op
->kp
.addr
= p
->addr
;
729 arch_prepare_optimized_kprobe(op
);
734 static void __kprobes
init_aggr_kprobe(struct kprobe
*ap
, struct kprobe
*p
);
737 * Prepare an optimized_kprobe and optimize it
738 * NOTE: p must be a normal registered kprobe
740 static __kprobes
void try_to_optimize_kprobe(struct kprobe
*p
)
743 struct optimized_kprobe
*op
;
745 /* Impossible to optimize ftrace-based kprobe */
746 if (kprobe_ftrace(p
))
749 /* For preparing optimization, jump_label_text_reserved() is called */
751 mutex_lock(&text_mutex
);
753 ap
= alloc_aggr_kprobe(p
);
757 op
= container_of(ap
, struct optimized_kprobe
, kp
);
758 if (!arch_prepared_optinsn(&op
->optinsn
)) {
759 /* If failed to setup optimizing, fallback to kprobe */
760 arch_remove_optimized_kprobe(op
);
765 init_aggr_kprobe(ap
, p
);
766 optimize_kprobe(ap
); /* This just kicks optimizer thread */
769 mutex_unlock(&text_mutex
);
774 static void __kprobes
optimize_all_kprobes(void)
776 struct hlist_head
*head
;
780 mutex_lock(&kprobe_mutex
);
781 /* If optimization is already allowed, just return */
782 if (kprobes_allow_optimization
)
785 kprobes_allow_optimization
= true;
786 for (i
= 0; i
< KPROBE_TABLE_SIZE
; i
++) {
787 head
= &kprobe_table
[i
];
788 hlist_for_each_entry_rcu(p
, head
, hlist
)
789 if (!kprobe_disabled(p
))
792 printk(KERN_INFO
"Kprobes globally optimized\n");
794 mutex_unlock(&kprobe_mutex
);
797 static void __kprobes
unoptimize_all_kprobes(void)
799 struct hlist_head
*head
;
803 mutex_lock(&kprobe_mutex
);
804 /* If optimization is already prohibited, just return */
805 if (!kprobes_allow_optimization
) {
806 mutex_unlock(&kprobe_mutex
);
810 kprobes_allow_optimization
= false;
811 for (i
= 0; i
< KPROBE_TABLE_SIZE
; i
++) {
812 head
= &kprobe_table
[i
];
813 hlist_for_each_entry_rcu(p
, head
, hlist
) {
814 if (!kprobe_disabled(p
))
815 unoptimize_kprobe(p
, false);
818 mutex_unlock(&kprobe_mutex
);
820 /* Wait for unoptimizing completion */
821 wait_for_kprobe_optimizer();
822 printk(KERN_INFO
"Kprobes globally unoptimized\n");
825 static DEFINE_MUTEX(kprobe_sysctl_mutex
);
826 int sysctl_kprobes_optimization
;
827 int proc_kprobes_optimization_handler(struct ctl_table
*table
, int write
,
828 void __user
*buffer
, size_t *length
,
833 mutex_lock(&kprobe_sysctl_mutex
);
834 sysctl_kprobes_optimization
= kprobes_allow_optimization
? 1 : 0;
835 ret
= proc_dointvec_minmax(table
, write
, buffer
, length
, ppos
);
837 if (sysctl_kprobes_optimization
)
838 optimize_all_kprobes();
840 unoptimize_all_kprobes();
841 mutex_unlock(&kprobe_sysctl_mutex
);
845 #endif /* CONFIG_SYSCTL */
847 /* Put a breakpoint for a probe. Must be called with text_mutex locked */
848 static void __kprobes
__arm_kprobe(struct kprobe
*p
)
852 /* Check collision with other optimized kprobes */
853 _p
= get_optimized_kprobe((unsigned long)p
->addr
);
855 /* Fallback to unoptimized kprobe */
856 unoptimize_kprobe(_p
, true);
859 optimize_kprobe(p
); /* Try to optimize (add kprobe to a list) */
862 /* Remove the breakpoint of a probe. Must be called with text_mutex locked */
863 static void __kprobes
__disarm_kprobe(struct kprobe
*p
, bool reopt
)
867 unoptimize_kprobe(p
, false); /* Try to unoptimize */
869 if (!kprobe_queued(p
)) {
870 arch_disarm_kprobe(p
);
871 /* If another kprobe was blocked, optimize it. */
872 _p
= get_optimized_kprobe((unsigned long)p
->addr
);
873 if (unlikely(_p
) && reopt
)
876 /* TODO: reoptimize others after unoptimized this probe */
879 #else /* !CONFIG_OPTPROBES */
881 #define optimize_kprobe(p) do {} while (0)
882 #define unoptimize_kprobe(p, f) do {} while (0)
883 #define kill_optimized_kprobe(p) do {} while (0)
884 #define prepare_optimized_kprobe(p) do {} while (0)
885 #define try_to_optimize_kprobe(p) do {} while (0)
886 #define __arm_kprobe(p) arch_arm_kprobe(p)
887 #define __disarm_kprobe(p, o) arch_disarm_kprobe(p)
888 #define kprobe_disarmed(p) kprobe_disabled(p)
889 #define wait_for_kprobe_optimizer() do {} while (0)
891 /* There should be no unused kprobes can be reused without optimization */
892 static void reuse_unused_kprobe(struct kprobe
*ap
)
894 printk(KERN_ERR
"Error: There should be no unused kprobe here.\n");
895 BUG_ON(kprobe_unused(ap
));
898 static __kprobes
void free_aggr_kprobe(struct kprobe
*p
)
900 arch_remove_kprobe(p
);
904 static __kprobes
struct kprobe
*alloc_aggr_kprobe(struct kprobe
*p
)
906 return kzalloc(sizeof(struct kprobe
), GFP_KERNEL
);
908 #endif /* CONFIG_OPTPROBES */
910 #ifdef CONFIG_KPROBES_ON_FTRACE
911 static struct ftrace_ops kprobe_ftrace_ops __read_mostly
= {
912 .func
= kprobe_ftrace_handler
,
913 .flags
= FTRACE_OPS_FL_SAVE_REGS
,
915 static int kprobe_ftrace_enabled
;
917 /* Must ensure p->addr is really on ftrace */
918 static int __kprobes
prepare_kprobe(struct kprobe
*p
)
920 if (!kprobe_ftrace(p
))
921 return arch_prepare_kprobe(p
);
923 return arch_prepare_kprobe_ftrace(p
);
926 /* Caller must lock kprobe_mutex */
927 static void __kprobes
arm_kprobe_ftrace(struct kprobe
*p
)
931 ret
= ftrace_set_filter_ip(&kprobe_ftrace_ops
,
932 (unsigned long)p
->addr
, 0, 0);
933 WARN(ret
< 0, "Failed to arm kprobe-ftrace at %p (%d)\n", p
->addr
, ret
);
934 kprobe_ftrace_enabled
++;
935 if (kprobe_ftrace_enabled
== 1) {
936 ret
= register_ftrace_function(&kprobe_ftrace_ops
);
937 WARN(ret
< 0, "Failed to init kprobe-ftrace (%d)\n", ret
);
941 /* Caller must lock kprobe_mutex */
942 static void __kprobes
disarm_kprobe_ftrace(struct kprobe
*p
)
946 kprobe_ftrace_enabled
--;
947 if (kprobe_ftrace_enabled
== 0) {
948 ret
= unregister_ftrace_function(&kprobe_ftrace_ops
);
949 WARN(ret
< 0, "Failed to init kprobe-ftrace (%d)\n", ret
);
951 ret
= ftrace_set_filter_ip(&kprobe_ftrace_ops
,
952 (unsigned long)p
->addr
, 1, 0);
953 WARN(ret
< 0, "Failed to disarm kprobe-ftrace at %p (%d)\n", p
->addr
, ret
);
955 #else /* !CONFIG_KPROBES_ON_FTRACE */
956 #define prepare_kprobe(p) arch_prepare_kprobe(p)
957 #define arm_kprobe_ftrace(p) do {} while (0)
958 #define disarm_kprobe_ftrace(p) do {} while (0)
961 /* Arm a kprobe with text_mutex */
962 static void __kprobes
arm_kprobe(struct kprobe
*kp
)
964 if (unlikely(kprobe_ftrace(kp
))) {
965 arm_kprobe_ftrace(kp
);
969 * Here, since __arm_kprobe() doesn't use stop_machine(),
970 * this doesn't cause deadlock on text_mutex. So, we don't
971 * need get_online_cpus().
973 mutex_lock(&text_mutex
);
975 mutex_unlock(&text_mutex
);
978 /* Disarm a kprobe with text_mutex */
979 static void __kprobes
disarm_kprobe(struct kprobe
*kp
, bool reopt
)
981 if (unlikely(kprobe_ftrace(kp
))) {
982 disarm_kprobe_ftrace(kp
);
986 mutex_lock(&text_mutex
);
987 __disarm_kprobe(kp
, reopt
);
988 mutex_unlock(&text_mutex
);
992 * Aggregate handlers for multiple kprobes support - these handlers
993 * take care of invoking the individual kprobe handlers on p->list
995 static int __kprobes
aggr_pre_handler(struct kprobe
*p
, struct pt_regs
*regs
)
999 list_for_each_entry_rcu(kp
, &p
->list
, list
) {
1000 if (kp
->pre_handler
&& likely(!kprobe_disabled(kp
))) {
1001 set_kprobe_instance(kp
);
1002 if (kp
->pre_handler(kp
, regs
))
1005 reset_kprobe_instance();
1010 static void __kprobes
aggr_post_handler(struct kprobe
*p
, struct pt_regs
*regs
,
1011 unsigned long flags
)
1015 list_for_each_entry_rcu(kp
, &p
->list
, list
) {
1016 if (kp
->post_handler
&& likely(!kprobe_disabled(kp
))) {
1017 set_kprobe_instance(kp
);
1018 kp
->post_handler(kp
, regs
, flags
);
1019 reset_kprobe_instance();
1024 static int __kprobes
aggr_fault_handler(struct kprobe
*p
, struct pt_regs
*regs
,
1027 struct kprobe
*cur
= __this_cpu_read(kprobe_instance
);
1030 * if we faulted "during" the execution of a user specified
1031 * probe handler, invoke just that probe's fault handler
1033 if (cur
&& cur
->fault_handler
) {
1034 if (cur
->fault_handler(cur
, regs
, trapnr
))
1040 static int __kprobes
aggr_break_handler(struct kprobe
*p
, struct pt_regs
*regs
)
1042 struct kprobe
*cur
= __this_cpu_read(kprobe_instance
);
1045 if (cur
&& cur
->break_handler
) {
1046 if (cur
->break_handler(cur
, regs
))
1049 reset_kprobe_instance();
1053 /* Walks the list and increments nmissed count for multiprobe case */
1054 void __kprobes
kprobes_inc_nmissed_count(struct kprobe
*p
)
1057 if (!kprobe_aggrprobe(p
)) {
1060 list_for_each_entry_rcu(kp
, &p
->list
, list
)
1066 void __kprobes
recycle_rp_inst(struct kretprobe_instance
*ri
,
1067 struct hlist_head
*head
)
1069 struct kretprobe
*rp
= ri
->rp
;
1071 /* remove rp inst off the rprobe_inst_table */
1072 hlist_del(&ri
->hlist
);
1073 INIT_HLIST_NODE(&ri
->hlist
);
1075 raw_spin_lock(&rp
->lock
);
1076 hlist_add_head(&ri
->hlist
, &rp
->free_instances
);
1077 raw_spin_unlock(&rp
->lock
);
1080 hlist_add_head(&ri
->hlist
, head
);
1083 void __kprobes
kretprobe_hash_lock(struct task_struct
*tsk
,
1084 struct hlist_head
**head
, unsigned long *flags
)
1085 __acquires(hlist_lock
)
1087 unsigned long hash
= hash_ptr(tsk
, KPROBE_HASH_BITS
);
1088 raw_spinlock_t
*hlist_lock
;
1090 *head
= &kretprobe_inst_table
[hash
];
1091 hlist_lock
= kretprobe_table_lock_ptr(hash
);
1092 raw_spin_lock_irqsave(hlist_lock
, *flags
);
1095 static void __kprobes
kretprobe_table_lock(unsigned long hash
,
1096 unsigned long *flags
)
1097 __acquires(hlist_lock
)
1099 raw_spinlock_t
*hlist_lock
= kretprobe_table_lock_ptr(hash
);
1100 raw_spin_lock_irqsave(hlist_lock
, *flags
);
1103 void __kprobes
kretprobe_hash_unlock(struct task_struct
*tsk
,
1104 unsigned long *flags
)
1105 __releases(hlist_lock
)
1107 unsigned long hash
= hash_ptr(tsk
, KPROBE_HASH_BITS
);
1108 raw_spinlock_t
*hlist_lock
;
1110 hlist_lock
= kretprobe_table_lock_ptr(hash
);
1111 raw_spin_unlock_irqrestore(hlist_lock
, *flags
);
1114 static void __kprobes
kretprobe_table_unlock(unsigned long hash
,
1115 unsigned long *flags
)
1116 __releases(hlist_lock
)
1118 raw_spinlock_t
*hlist_lock
= kretprobe_table_lock_ptr(hash
);
1119 raw_spin_unlock_irqrestore(hlist_lock
, *flags
);
1123 * This function is called from finish_task_switch when task tk becomes dead,
1124 * so that we can recycle any function-return probe instances associated
1125 * with this task. These left over instances represent probed functions
1126 * that have been called but will never return.
1128 void __kprobes
kprobe_flush_task(struct task_struct
*tk
)
1130 struct kretprobe_instance
*ri
;
1131 struct hlist_head
*head
, empty_rp
;
1132 struct hlist_node
*tmp
;
1133 unsigned long hash
, flags
= 0;
1135 if (unlikely(!kprobes_initialized
))
1136 /* Early boot. kretprobe_table_locks not yet initialized. */
1139 INIT_HLIST_HEAD(&empty_rp
);
1140 hash
= hash_ptr(tk
, KPROBE_HASH_BITS
);
1141 head
= &kretprobe_inst_table
[hash
];
1142 kretprobe_table_lock(hash
, &flags
);
1143 hlist_for_each_entry_safe(ri
, tmp
, head
, hlist
) {
1145 recycle_rp_inst(ri
, &empty_rp
);
1147 kretprobe_table_unlock(hash
, &flags
);
1148 hlist_for_each_entry_safe(ri
, tmp
, &empty_rp
, hlist
) {
1149 hlist_del(&ri
->hlist
);
1154 static inline void free_rp_inst(struct kretprobe
*rp
)
1156 struct kretprobe_instance
*ri
;
1157 struct hlist_node
*next
;
1159 hlist_for_each_entry_safe(ri
, next
, &rp
->free_instances
, hlist
) {
1160 hlist_del(&ri
->hlist
);
1165 static void __kprobes
cleanup_rp_inst(struct kretprobe
*rp
)
1167 unsigned long flags
, hash
;
1168 struct kretprobe_instance
*ri
;
1169 struct hlist_node
*next
;
1170 struct hlist_head
*head
;
1173 for (hash
= 0; hash
< KPROBE_TABLE_SIZE
; hash
++) {
1174 kretprobe_table_lock(hash
, &flags
);
1175 head
= &kretprobe_inst_table
[hash
];
1176 hlist_for_each_entry_safe(ri
, next
, head
, hlist
) {
1180 kretprobe_table_unlock(hash
, &flags
);
1186 * Add the new probe to ap->list. Fail if this is the
1187 * second jprobe at the address - two jprobes can't coexist
1189 static int __kprobes
add_new_kprobe(struct kprobe
*ap
, struct kprobe
*p
)
1191 BUG_ON(kprobe_gone(ap
) || kprobe_gone(p
));
1193 if (p
->break_handler
|| p
->post_handler
)
1194 unoptimize_kprobe(ap
, true); /* Fall back to normal kprobe */
1196 if (p
->break_handler
) {
1197 if (ap
->break_handler
)
1199 list_add_tail_rcu(&p
->list
, &ap
->list
);
1200 ap
->break_handler
= aggr_break_handler
;
1202 list_add_rcu(&p
->list
, &ap
->list
);
1203 if (p
->post_handler
&& !ap
->post_handler
)
1204 ap
->post_handler
= aggr_post_handler
;
1210 * Fill in the required fields of the "manager kprobe". Replace the
1211 * earlier kprobe in the hlist with the manager kprobe
1213 static void __kprobes
init_aggr_kprobe(struct kprobe
*ap
, struct kprobe
*p
)
1215 /* Copy p's insn slot to ap */
1217 flush_insn_slot(ap
);
1219 ap
->flags
= p
->flags
& ~KPROBE_FLAG_OPTIMIZED
;
1220 ap
->pre_handler
= aggr_pre_handler
;
1221 ap
->fault_handler
= aggr_fault_handler
;
1222 /* We don't care the kprobe which has gone. */
1223 if (p
->post_handler
&& !kprobe_gone(p
))
1224 ap
->post_handler
= aggr_post_handler
;
1225 if (p
->break_handler
&& !kprobe_gone(p
))
1226 ap
->break_handler
= aggr_break_handler
;
1228 INIT_LIST_HEAD(&ap
->list
);
1229 INIT_HLIST_NODE(&ap
->hlist
);
1231 list_add_rcu(&p
->list
, &ap
->list
);
1232 hlist_replace_rcu(&p
->hlist
, &ap
->hlist
);
1236 * This is the second or subsequent kprobe at the address - handle
1239 static int __kprobes
register_aggr_kprobe(struct kprobe
*orig_p
,
1243 struct kprobe
*ap
= orig_p
;
1245 /* For preparing optimization, jump_label_text_reserved() is called */
1248 * Get online CPUs to avoid text_mutex deadlock.with stop machine,
1249 * which is invoked by unoptimize_kprobe() in add_new_kprobe()
1252 mutex_lock(&text_mutex
);
1254 if (!kprobe_aggrprobe(orig_p
)) {
1255 /* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */
1256 ap
= alloc_aggr_kprobe(orig_p
);
1261 init_aggr_kprobe(ap
, orig_p
);
1262 } else if (kprobe_unused(ap
))
1263 /* This probe is going to die. Rescue it */
1264 reuse_unused_kprobe(ap
);
1266 if (kprobe_gone(ap
)) {
1268 * Attempting to insert new probe at the same location that
1269 * had a probe in the module vaddr area which already
1270 * freed. So, the instruction slot has already been
1271 * released. We need a new slot for the new probe.
1273 ret
= arch_prepare_kprobe(ap
);
1276 * Even if fail to allocate new slot, don't need to
1277 * free aggr_probe. It will be used next time, or
1278 * freed by unregister_kprobe.
1282 /* Prepare optimized instructions if possible. */
1283 prepare_optimized_kprobe(ap
);
1286 * Clear gone flag to prevent allocating new slot again, and
1287 * set disabled flag because it is not armed yet.
1289 ap
->flags
= (ap
->flags
& ~KPROBE_FLAG_GONE
)
1290 | KPROBE_FLAG_DISABLED
;
1293 /* Copy ap's insn slot to p */
1295 ret
= add_new_kprobe(ap
, p
);
1298 mutex_unlock(&text_mutex
);
1300 jump_label_unlock();
1302 if (ret
== 0 && kprobe_disabled(ap
) && !kprobe_disabled(p
)) {
1303 ap
->flags
&= ~KPROBE_FLAG_DISABLED
;
1304 if (!kprobes_all_disarmed
)
1305 /* Arm the breakpoint again. */
1311 static int __kprobes
in_kprobes_functions(unsigned long addr
)
1313 struct kprobe_blackpoint
*kb
;
1315 if (addr
>= (unsigned long)__kprobes_text_start
&&
1316 addr
< (unsigned long)__kprobes_text_end
)
1319 * If there exists a kprobe_blacklist, verify and
1320 * fail any probe registration in the prohibited area
1322 for (kb
= kprobe_blacklist
; kb
->name
!= NULL
; kb
++) {
1323 if (kb
->start_addr
) {
1324 if (addr
>= kb
->start_addr
&&
1325 addr
< (kb
->start_addr
+ kb
->range
))
1333 * If we have a symbol_name argument, look it up and add the offset field
1334 * to it. This way, we can specify a relative address to a symbol.
1335 * This returns encoded errors if it fails to look up symbol or invalid
1336 * combination of parameters.
1338 static kprobe_opcode_t __kprobes
*kprobe_addr(struct kprobe
*p
)
1340 kprobe_opcode_t
*addr
= p
->addr
;
1342 if ((p
->symbol_name
&& p
->addr
) ||
1343 (!p
->symbol_name
&& !p
->addr
))
1346 if (p
->symbol_name
) {
1347 kprobe_lookup_name(p
->symbol_name
, addr
);
1349 return ERR_PTR(-ENOENT
);
1352 addr
= (kprobe_opcode_t
*)(((char *)addr
) + p
->offset
);
1357 return ERR_PTR(-EINVAL
);
1360 /* Check passed kprobe is valid and return kprobe in kprobe_table. */
1361 static struct kprobe
* __kprobes
__get_valid_kprobe(struct kprobe
*p
)
1363 struct kprobe
*ap
, *list_p
;
1365 ap
= get_kprobe(p
->addr
);
1370 list_for_each_entry_rcu(list_p
, &ap
->list
, list
)
1372 /* kprobe p is a valid probe */
1380 /* Return error if the kprobe is being re-registered */
1381 static inline int check_kprobe_rereg(struct kprobe
*p
)
1385 mutex_lock(&kprobe_mutex
);
1386 if (__get_valid_kprobe(p
))
1388 mutex_unlock(&kprobe_mutex
);
1393 static __kprobes
int check_kprobe_address_safe(struct kprobe
*p
,
1394 struct module
**probed_mod
)
1397 unsigned long ftrace_addr
;
1400 * If the address is located on a ftrace nop, set the
1401 * breakpoint to the following instruction.
1403 ftrace_addr
= ftrace_location((unsigned long)p
->addr
);
1405 #ifdef CONFIG_KPROBES_ON_FTRACE
1406 /* Given address is not on the instruction boundary */
1407 if ((unsigned long)p
->addr
!= ftrace_addr
)
1409 p
->flags
|= KPROBE_FLAG_FTRACE
;
1410 #else /* !CONFIG_KPROBES_ON_FTRACE */
1418 /* Ensure it is not in reserved area nor out of text */
1419 if (!kernel_text_address((unsigned long) p
->addr
) ||
1420 in_kprobes_functions((unsigned long) p
->addr
) ||
1421 jump_label_text_reserved(p
->addr
, p
->addr
)) {
1426 /* Check if are we probing a module */
1427 *probed_mod
= __module_text_address((unsigned long) p
->addr
);
1430 * We must hold a refcount of the probed module while updating
1431 * its code to prohibit unexpected unloading.
1433 if (unlikely(!try_module_get(*probed_mod
))) {
1439 * If the module freed .init.text, we couldn't insert
1442 if (within_module_init((unsigned long)p
->addr
, *probed_mod
) &&
1443 (*probed_mod
)->state
!= MODULE_STATE_COMING
) {
1444 module_put(*probed_mod
);
1451 jump_label_unlock();
1456 int __kprobes
register_kprobe(struct kprobe
*p
)
1459 struct kprobe
*old_p
;
1460 struct module
*probed_mod
;
1461 kprobe_opcode_t
*addr
;
1463 /* Adjust probe address from symbol */
1464 addr
= kprobe_addr(p
);
1466 return PTR_ERR(addr
);
1469 ret
= check_kprobe_rereg(p
);
1473 /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
1474 p
->flags
&= KPROBE_FLAG_DISABLED
;
1476 INIT_LIST_HEAD(&p
->list
);
1478 ret
= check_kprobe_address_safe(p
, &probed_mod
);
1482 mutex_lock(&kprobe_mutex
);
1484 old_p
= get_kprobe(p
->addr
);
1486 /* Since this may unoptimize old_p, locking text_mutex. */
1487 ret
= register_aggr_kprobe(old_p
, p
);
1491 mutex_lock(&text_mutex
); /* Avoiding text modification */
1492 ret
= prepare_kprobe(p
);
1493 mutex_unlock(&text_mutex
);
1497 INIT_HLIST_NODE(&p
->hlist
);
1498 hlist_add_head_rcu(&p
->hlist
,
1499 &kprobe_table
[hash_ptr(p
->addr
, KPROBE_HASH_BITS
)]);
1501 if (!kprobes_all_disarmed
&& !kprobe_disabled(p
))
1504 /* Try to optimize kprobe */
1505 try_to_optimize_kprobe(p
);
1508 mutex_unlock(&kprobe_mutex
);
1511 module_put(probed_mod
);
1515 EXPORT_SYMBOL_GPL(register_kprobe
);
1517 /* Check if all probes on the aggrprobe are disabled */
1518 static int __kprobes
aggr_kprobe_disabled(struct kprobe
*ap
)
1522 list_for_each_entry_rcu(kp
, &ap
->list
, list
)
1523 if (!kprobe_disabled(kp
))
1525 * There is an active probe on the list.
1526 * We can't disable this ap.
1533 /* Disable one kprobe: Make sure called under kprobe_mutex is locked */
1534 static struct kprobe
*__kprobes
__disable_kprobe(struct kprobe
*p
)
1536 struct kprobe
*orig_p
;
1538 /* Get an original kprobe for return */
1539 orig_p
= __get_valid_kprobe(p
);
1540 if (unlikely(orig_p
== NULL
))
1543 if (!kprobe_disabled(p
)) {
1544 /* Disable probe if it is a child probe */
1546 p
->flags
|= KPROBE_FLAG_DISABLED
;
1548 /* Try to disarm and disable this/parent probe */
1549 if (p
== orig_p
|| aggr_kprobe_disabled(orig_p
)) {
1550 disarm_kprobe(orig_p
, true);
1551 orig_p
->flags
|= KPROBE_FLAG_DISABLED
;
1559 * Unregister a kprobe without a scheduler synchronization.
1561 static int __kprobes
__unregister_kprobe_top(struct kprobe
*p
)
1563 struct kprobe
*ap
, *list_p
;
1565 /* Disable kprobe. This will disarm it if needed. */
1566 ap
= __disable_kprobe(p
);
1572 * This probe is an independent(and non-optimized) kprobe
1573 * (not an aggrprobe). Remove from the hash list.
1577 /* Following process expects this probe is an aggrprobe */
1578 WARN_ON(!kprobe_aggrprobe(ap
));
1580 if (list_is_singular(&ap
->list
) && kprobe_disarmed(ap
))
1582 * !disarmed could be happen if the probe is under delayed
1587 /* If disabling probe has special handlers, update aggrprobe */
1588 if (p
->break_handler
&& !kprobe_gone(p
))
1589 ap
->break_handler
= NULL
;
1590 if (p
->post_handler
&& !kprobe_gone(p
)) {
1591 list_for_each_entry_rcu(list_p
, &ap
->list
, list
) {
1592 if ((list_p
!= p
) && (list_p
->post_handler
))
1595 ap
->post_handler
= NULL
;
1599 * Remove from the aggrprobe: this path will do nothing in
1600 * __unregister_kprobe_bottom().
1602 list_del_rcu(&p
->list
);
1603 if (!kprobe_disabled(ap
) && !kprobes_all_disarmed
)
1605 * Try to optimize this probe again, because post
1606 * handler may have been changed.
1608 optimize_kprobe(ap
);
1613 BUG_ON(!kprobe_disarmed(ap
));
1614 hlist_del_rcu(&ap
->hlist
);
1618 static void __kprobes
__unregister_kprobe_bottom(struct kprobe
*p
)
1622 if (list_empty(&p
->list
))
1623 /* This is an independent kprobe */
1624 arch_remove_kprobe(p
);
1625 else if (list_is_singular(&p
->list
)) {
1626 /* This is the last child of an aggrprobe */
1627 ap
= list_entry(p
->list
.next
, struct kprobe
, list
);
1629 free_aggr_kprobe(ap
);
1631 /* Otherwise, do nothing. */
1634 int __kprobes
register_kprobes(struct kprobe
**kps
, int num
)
1640 for (i
= 0; i
< num
; i
++) {
1641 ret
= register_kprobe(kps
[i
]);
1644 unregister_kprobes(kps
, i
);
1650 EXPORT_SYMBOL_GPL(register_kprobes
);
1652 void __kprobes
unregister_kprobe(struct kprobe
*p
)
1654 unregister_kprobes(&p
, 1);
1656 EXPORT_SYMBOL_GPL(unregister_kprobe
);
1658 void __kprobes
unregister_kprobes(struct kprobe
**kps
, int num
)
1664 mutex_lock(&kprobe_mutex
);
1665 for (i
= 0; i
< num
; i
++)
1666 if (__unregister_kprobe_top(kps
[i
]) < 0)
1667 kps
[i
]->addr
= NULL
;
1668 mutex_unlock(&kprobe_mutex
);
1670 synchronize_sched();
1671 for (i
= 0; i
< num
; i
++)
1673 __unregister_kprobe_bottom(kps
[i
]);
1675 EXPORT_SYMBOL_GPL(unregister_kprobes
);
1677 static struct notifier_block kprobe_exceptions_nb
= {
1678 .notifier_call
= kprobe_exceptions_notify
,
1679 .priority
= 0x7fffffff /* we need to be notified first */
1682 unsigned long __weak
arch_deref_entry_point(void *entry
)
1684 return (unsigned long)entry
;
1687 int __kprobes
register_jprobes(struct jprobe
**jps
, int num
)
1694 for (i
= 0; i
< num
; i
++) {
1695 unsigned long addr
, offset
;
1697 addr
= arch_deref_entry_point(jp
->entry
);
1699 /* Verify probepoint is a function entry point */
1700 if (kallsyms_lookup_size_offset(addr
, NULL
, &offset
) &&
1702 jp
->kp
.pre_handler
= setjmp_pre_handler
;
1703 jp
->kp
.break_handler
= longjmp_break_handler
;
1704 ret
= register_kprobe(&jp
->kp
);
1710 unregister_jprobes(jps
, i
);
1716 EXPORT_SYMBOL_GPL(register_jprobes
);
1718 int __kprobes
register_jprobe(struct jprobe
*jp
)
1720 return register_jprobes(&jp
, 1);
1722 EXPORT_SYMBOL_GPL(register_jprobe
);
1724 void __kprobes
unregister_jprobe(struct jprobe
*jp
)
1726 unregister_jprobes(&jp
, 1);
1728 EXPORT_SYMBOL_GPL(unregister_jprobe
);
1730 void __kprobes
unregister_jprobes(struct jprobe
**jps
, int num
)
1736 mutex_lock(&kprobe_mutex
);
1737 for (i
= 0; i
< num
; i
++)
1738 if (__unregister_kprobe_top(&jps
[i
]->kp
) < 0)
1739 jps
[i
]->kp
.addr
= NULL
;
1740 mutex_unlock(&kprobe_mutex
);
1742 synchronize_sched();
1743 for (i
= 0; i
< num
; i
++) {
1744 if (jps
[i
]->kp
.addr
)
1745 __unregister_kprobe_bottom(&jps
[i
]->kp
);
1748 EXPORT_SYMBOL_GPL(unregister_jprobes
);
1750 #ifdef CONFIG_KRETPROBES
1752 * This kprobe pre_handler is registered with every kretprobe. When probe
1753 * hits it will set up the return probe.
1755 static int __kprobes
pre_handler_kretprobe(struct kprobe
*p
,
1756 struct pt_regs
*regs
)
1758 struct kretprobe
*rp
= container_of(p
, struct kretprobe
, kp
);
1759 unsigned long hash
, flags
= 0;
1760 struct kretprobe_instance
*ri
;
1762 /*TODO: consider to only swap the RA after the last pre_handler fired */
1763 hash
= hash_ptr(current
, KPROBE_HASH_BITS
);
1764 raw_spin_lock_irqsave(&rp
->lock
, flags
);
1765 if (!hlist_empty(&rp
->free_instances
)) {
1766 ri
= hlist_entry(rp
->free_instances
.first
,
1767 struct kretprobe_instance
, hlist
);
1768 hlist_del(&ri
->hlist
);
1769 raw_spin_unlock_irqrestore(&rp
->lock
, flags
);
1774 if (rp
->entry_handler
&& rp
->entry_handler(ri
, regs
)) {
1775 raw_spin_lock_irqsave(&rp
->lock
, flags
);
1776 hlist_add_head(&ri
->hlist
, &rp
->free_instances
);
1777 raw_spin_unlock_irqrestore(&rp
->lock
, flags
);
1781 arch_prepare_kretprobe(ri
, regs
);
1783 /* XXX(hch): why is there no hlist_move_head? */
1784 INIT_HLIST_NODE(&ri
->hlist
);
1785 kretprobe_table_lock(hash
, &flags
);
1786 hlist_add_head(&ri
->hlist
, &kretprobe_inst_table
[hash
]);
1787 kretprobe_table_unlock(hash
, &flags
);
1790 raw_spin_unlock_irqrestore(&rp
->lock
, flags
);
1795 int __kprobes
register_kretprobe(struct kretprobe
*rp
)
1798 struct kretprobe_instance
*inst
;
1802 if (kretprobe_blacklist_size
) {
1803 addr
= kprobe_addr(&rp
->kp
);
1805 return PTR_ERR(addr
);
1807 for (i
= 0; kretprobe_blacklist
[i
].name
!= NULL
; i
++) {
1808 if (kretprobe_blacklist
[i
].addr
== addr
)
1813 rp
->kp
.pre_handler
= pre_handler_kretprobe
;
1814 rp
->kp
.post_handler
= NULL
;
1815 rp
->kp
.fault_handler
= NULL
;
1816 rp
->kp
.break_handler
= NULL
;
1818 /* Pre-allocate memory for max kretprobe instances */
1819 if (rp
->maxactive
<= 0) {
1820 #ifdef CONFIG_PREEMPT
1821 rp
->maxactive
= max_t(unsigned int, 10, 2*num_possible_cpus());
1823 rp
->maxactive
= num_possible_cpus();
1826 raw_spin_lock_init(&rp
->lock
);
1827 INIT_HLIST_HEAD(&rp
->free_instances
);
1828 for (i
= 0; i
< rp
->maxactive
; i
++) {
1829 inst
= kmalloc(sizeof(struct kretprobe_instance
) +
1830 rp
->data_size
, GFP_KERNEL
);
1835 INIT_HLIST_NODE(&inst
->hlist
);
1836 hlist_add_head(&inst
->hlist
, &rp
->free_instances
);
1840 /* Establish function entry probe point */
1841 ret
= register_kprobe(&rp
->kp
);
1846 EXPORT_SYMBOL_GPL(register_kretprobe
);
1848 int __kprobes
register_kretprobes(struct kretprobe
**rps
, int num
)
1854 for (i
= 0; i
< num
; i
++) {
1855 ret
= register_kretprobe(rps
[i
]);
1858 unregister_kretprobes(rps
, i
);
1864 EXPORT_SYMBOL_GPL(register_kretprobes
);
1866 void __kprobes
unregister_kretprobe(struct kretprobe
*rp
)
1868 unregister_kretprobes(&rp
, 1);
1870 EXPORT_SYMBOL_GPL(unregister_kretprobe
);
1872 void __kprobes
unregister_kretprobes(struct kretprobe
**rps
, int num
)
1878 mutex_lock(&kprobe_mutex
);
1879 for (i
= 0; i
< num
; i
++)
1880 if (__unregister_kprobe_top(&rps
[i
]->kp
) < 0)
1881 rps
[i
]->kp
.addr
= NULL
;
1882 mutex_unlock(&kprobe_mutex
);
1884 synchronize_sched();
1885 for (i
= 0; i
< num
; i
++) {
1886 if (rps
[i
]->kp
.addr
) {
1887 __unregister_kprobe_bottom(&rps
[i
]->kp
);
1888 cleanup_rp_inst(rps
[i
]);
1892 EXPORT_SYMBOL_GPL(unregister_kretprobes
);
1894 #else /* CONFIG_KRETPROBES */
1895 int __kprobes
register_kretprobe(struct kretprobe
*rp
)
1899 EXPORT_SYMBOL_GPL(register_kretprobe
);
1901 int __kprobes
register_kretprobes(struct kretprobe
**rps
, int num
)
1905 EXPORT_SYMBOL_GPL(register_kretprobes
);
1907 void __kprobes
unregister_kretprobe(struct kretprobe
*rp
)
1910 EXPORT_SYMBOL_GPL(unregister_kretprobe
);
1912 void __kprobes
unregister_kretprobes(struct kretprobe
**rps
, int num
)
1915 EXPORT_SYMBOL_GPL(unregister_kretprobes
);
1917 static int __kprobes
pre_handler_kretprobe(struct kprobe
*p
,
1918 struct pt_regs
*regs
)
1923 #endif /* CONFIG_KRETPROBES */
1925 /* Set the kprobe gone and remove its instruction buffer. */
1926 static void __kprobes
kill_kprobe(struct kprobe
*p
)
1930 p
->flags
|= KPROBE_FLAG_GONE
;
1931 if (kprobe_aggrprobe(p
)) {
1933 * If this is an aggr_kprobe, we have to list all the
1934 * chained probes and mark them GONE.
1936 list_for_each_entry_rcu(kp
, &p
->list
, list
)
1937 kp
->flags
|= KPROBE_FLAG_GONE
;
1938 p
->post_handler
= NULL
;
1939 p
->break_handler
= NULL
;
1940 kill_optimized_kprobe(p
);
1943 * Here, we can remove insn_slot safely, because no thread calls
1944 * the original probed function (which will be freed soon) any more.
1946 arch_remove_kprobe(p
);
1949 /* Disable one kprobe */
1950 int __kprobes
disable_kprobe(struct kprobe
*kp
)
1954 mutex_lock(&kprobe_mutex
);
1956 /* Disable this kprobe */
1957 if (__disable_kprobe(kp
) == NULL
)
1960 mutex_unlock(&kprobe_mutex
);
1963 EXPORT_SYMBOL_GPL(disable_kprobe
);
1965 /* Enable one kprobe */
1966 int __kprobes
enable_kprobe(struct kprobe
*kp
)
1971 mutex_lock(&kprobe_mutex
);
1973 /* Check whether specified probe is valid. */
1974 p
= __get_valid_kprobe(kp
);
1975 if (unlikely(p
== NULL
)) {
1980 if (kprobe_gone(kp
)) {
1981 /* This kprobe has gone, we couldn't enable it. */
1987 kp
->flags
&= ~KPROBE_FLAG_DISABLED
;
1989 if (!kprobes_all_disarmed
&& kprobe_disabled(p
)) {
1990 p
->flags
&= ~KPROBE_FLAG_DISABLED
;
1994 mutex_unlock(&kprobe_mutex
);
1997 EXPORT_SYMBOL_GPL(enable_kprobe
);
1999 void __kprobes
dump_kprobe(struct kprobe
*kp
)
2001 printk(KERN_WARNING
"Dumping kprobe:\n");
2002 printk(KERN_WARNING
"Name: %s\nAddress: %p\nOffset: %x\n",
2003 kp
->symbol_name
, kp
->addr
, kp
->offset
);
2006 /* Module notifier call back, checking kprobes on the module */
2007 static int __kprobes
kprobes_module_callback(struct notifier_block
*nb
,
2008 unsigned long val
, void *data
)
2010 struct module
*mod
= data
;
2011 struct hlist_head
*head
;
2014 int checkcore
= (val
== MODULE_STATE_GOING
);
2016 if (val
!= MODULE_STATE_GOING
&& val
!= MODULE_STATE_LIVE
)
2020 * When MODULE_STATE_GOING was notified, both of module .text and
2021 * .init.text sections would be freed. When MODULE_STATE_LIVE was
2022 * notified, only .init.text section would be freed. We need to
2023 * disable kprobes which have been inserted in the sections.
2025 mutex_lock(&kprobe_mutex
);
2026 for (i
= 0; i
< KPROBE_TABLE_SIZE
; i
++) {
2027 head
= &kprobe_table
[i
];
2028 hlist_for_each_entry_rcu(p
, head
, hlist
)
2029 if (within_module_init((unsigned long)p
->addr
, mod
) ||
2031 within_module_core((unsigned long)p
->addr
, mod
))) {
2033 * The vaddr this probe is installed will soon
2034 * be vfreed buy not synced to disk. Hence,
2035 * disarming the breakpoint isn't needed.
2040 mutex_unlock(&kprobe_mutex
);
2044 static struct notifier_block kprobe_module_nb
= {
2045 .notifier_call
= kprobes_module_callback
,
2049 static int __init
init_kprobes(void)
2052 unsigned long offset
= 0, size
= 0;
2053 char *modname
, namebuf
[128];
2054 const char *symbol_name
;
2056 struct kprobe_blackpoint
*kb
;
2058 /* FIXME allocate the probe table, currently defined statically */
2059 /* initialize all list heads */
2060 for (i
= 0; i
< KPROBE_TABLE_SIZE
; i
++) {
2061 INIT_HLIST_HEAD(&kprobe_table
[i
]);
2062 INIT_HLIST_HEAD(&kretprobe_inst_table
[i
]);
2063 raw_spin_lock_init(&(kretprobe_table_locks
[i
].lock
));
2067 * Lookup and populate the kprobe_blacklist.
2069 * Unlike the kretprobe blacklist, we'll need to determine
2070 * the range of addresses that belong to the said functions,
2071 * since a kprobe need not necessarily be at the beginning
2074 for (kb
= kprobe_blacklist
; kb
->name
!= NULL
; kb
++) {
2075 kprobe_lookup_name(kb
->name
, addr
);
2079 kb
->start_addr
= (unsigned long)addr
;
2080 symbol_name
= kallsyms_lookup(kb
->start_addr
,
2081 &size
, &offset
, &modname
, namebuf
);
2088 if (kretprobe_blacklist_size
) {
2089 /* lookup the function address from its name */
2090 for (i
= 0; kretprobe_blacklist
[i
].name
!= NULL
; i
++) {
2091 kprobe_lookup_name(kretprobe_blacklist
[i
].name
,
2092 kretprobe_blacklist
[i
].addr
);
2093 if (!kretprobe_blacklist
[i
].addr
)
2094 printk("kretprobe: lookup failed: %s\n",
2095 kretprobe_blacklist
[i
].name
);
2099 #if defined(CONFIG_OPTPROBES)
2100 #if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
2101 /* Init kprobe_optinsn_slots */
2102 kprobe_optinsn_slots
.insn_size
= MAX_OPTINSN_SIZE
;
2104 /* By default, kprobes can be optimized */
2105 kprobes_allow_optimization
= true;
2108 /* By default, kprobes are armed */
2109 kprobes_all_disarmed
= false;
2111 err
= arch_init_kprobes();
2113 err
= register_die_notifier(&kprobe_exceptions_nb
);
2115 err
= register_module_notifier(&kprobe_module_nb
);
2117 kprobes_initialized
= (err
== 0);
2124 #ifdef CONFIG_DEBUG_FS
2125 static void __kprobes
report_probe(struct seq_file
*pi
, struct kprobe
*p
,
2126 const char *sym
, int offset
, char *modname
, struct kprobe
*pp
)
2130 if (p
->pre_handler
== pre_handler_kretprobe
)
2132 else if (p
->pre_handler
== setjmp_pre_handler
)
2138 seq_printf(pi
, "%p %s %s+0x%x %s ",
2139 p
->addr
, kprobe_type
, sym
, offset
,
2140 (modname
? modname
: " "));
2142 seq_printf(pi
, "%p %s %p ",
2143 p
->addr
, kprobe_type
, p
->addr
);
2147 seq_printf(pi
, "%s%s%s%s\n",
2148 (kprobe_gone(p
) ? "[GONE]" : ""),
2149 ((kprobe_disabled(p
) && !kprobe_gone(p
)) ? "[DISABLED]" : ""),
2150 (kprobe_optimized(pp
) ? "[OPTIMIZED]" : ""),
2151 (kprobe_ftrace(pp
) ? "[FTRACE]" : ""));
2154 static void __kprobes
*kprobe_seq_start(struct seq_file
*f
, loff_t
*pos
)
2156 return (*pos
< KPROBE_TABLE_SIZE
) ? pos
: NULL
;
2159 static void __kprobes
*kprobe_seq_next(struct seq_file
*f
, void *v
, loff_t
*pos
)
2162 if (*pos
>= KPROBE_TABLE_SIZE
)
2167 static void __kprobes
kprobe_seq_stop(struct seq_file
*f
, void *v
)
2172 static int __kprobes
show_kprobe_addr(struct seq_file
*pi
, void *v
)
2174 struct hlist_head
*head
;
2175 struct kprobe
*p
, *kp
;
2176 const char *sym
= NULL
;
2177 unsigned int i
= *(loff_t
*) v
;
2178 unsigned long offset
= 0;
2179 char *modname
, namebuf
[128];
2181 head
= &kprobe_table
[i
];
2183 hlist_for_each_entry_rcu(p
, head
, hlist
) {
2184 sym
= kallsyms_lookup((unsigned long)p
->addr
, NULL
,
2185 &offset
, &modname
, namebuf
);
2186 if (kprobe_aggrprobe(p
)) {
2187 list_for_each_entry_rcu(kp
, &p
->list
, list
)
2188 report_probe(pi
, kp
, sym
, offset
, modname
, p
);
2190 report_probe(pi
, p
, sym
, offset
, modname
, NULL
);
2196 static const struct seq_operations kprobes_seq_ops
= {
2197 .start
= kprobe_seq_start
,
2198 .next
= kprobe_seq_next
,
2199 .stop
= kprobe_seq_stop
,
2200 .show
= show_kprobe_addr
2203 static int __kprobes
kprobes_open(struct inode
*inode
, struct file
*filp
)
2205 return seq_open(filp
, &kprobes_seq_ops
);
2208 static const struct file_operations debugfs_kprobes_operations
= {
2209 .open
= kprobes_open
,
2211 .llseek
= seq_lseek
,
2212 .release
= seq_release
,
2215 static void __kprobes
arm_all_kprobes(void)
2217 struct hlist_head
*head
;
2221 mutex_lock(&kprobe_mutex
);
2223 /* If kprobes are armed, just return */
2224 if (!kprobes_all_disarmed
)
2225 goto already_enabled
;
2227 /* Arming kprobes doesn't optimize kprobe itself */
2228 for (i
= 0; i
< KPROBE_TABLE_SIZE
; i
++) {
2229 head
= &kprobe_table
[i
];
2230 hlist_for_each_entry_rcu(p
, head
, hlist
)
2231 if (!kprobe_disabled(p
))
2235 kprobes_all_disarmed
= false;
2236 printk(KERN_INFO
"Kprobes globally enabled\n");
2239 mutex_unlock(&kprobe_mutex
);
2243 static void __kprobes
disarm_all_kprobes(void)
2245 struct hlist_head
*head
;
2249 mutex_lock(&kprobe_mutex
);
2251 /* If kprobes are already disarmed, just return */
2252 if (kprobes_all_disarmed
) {
2253 mutex_unlock(&kprobe_mutex
);
2257 kprobes_all_disarmed
= true;
2258 printk(KERN_INFO
"Kprobes globally disabled\n");
2260 for (i
= 0; i
< KPROBE_TABLE_SIZE
; i
++) {
2261 head
= &kprobe_table
[i
];
2262 hlist_for_each_entry_rcu(p
, head
, hlist
) {
2263 if (!arch_trampoline_kprobe(p
) && !kprobe_disabled(p
))
2264 disarm_kprobe(p
, false);
2267 mutex_unlock(&kprobe_mutex
);
2269 /* Wait for disarming all kprobes by optimizer */
2270 wait_for_kprobe_optimizer();
2274 * XXX: The debugfs bool file interface doesn't allow for callbacks
2275 * when the bool state is switched. We can reuse that facility when
2278 static ssize_t
read_enabled_file_bool(struct file
*file
,
2279 char __user
*user_buf
, size_t count
, loff_t
*ppos
)
2283 if (!kprobes_all_disarmed
)
2289 return simple_read_from_buffer(user_buf
, count
, ppos
, buf
, 2);
2292 static ssize_t
write_enabled_file_bool(struct file
*file
,
2293 const char __user
*user_buf
, size_t count
, loff_t
*ppos
)
2298 buf_size
= min(count
, (sizeof(buf
)-1));
2299 if (copy_from_user(buf
, user_buf
, buf_size
))
2302 buf
[buf_size
] = '\0';
2312 disarm_all_kprobes();
2321 static const struct file_operations fops_kp
= {
2322 .read
= read_enabled_file_bool
,
2323 .write
= write_enabled_file_bool
,
2324 .llseek
= default_llseek
,
2327 static int __kprobes
debugfs_kprobe_init(void)
2329 struct dentry
*dir
, *file
;
2330 unsigned int value
= 1;
2332 dir
= debugfs_create_dir("kprobes", NULL
);
2336 file
= debugfs_create_file("list", 0444, dir
, NULL
,
2337 &debugfs_kprobes_operations
);
2339 debugfs_remove(dir
);
2343 file
= debugfs_create_file("enabled", 0600, dir
,
2346 debugfs_remove(dir
);
2353 late_initcall(debugfs_kprobe_init
);
2354 #endif /* CONFIG_DEBUG_FS */
2356 module_init(init_kprobes
);
2358 /* defined in arch/.../kernel/kprobes.c */
2359 EXPORT_SYMBOL_GPL(jprobe_return
);