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 */
115 struct kprobe_insn_cache
*cache
;
121 #define KPROBE_INSN_PAGE_SIZE(slots) \
122 (offsetof(struct kprobe_insn_page, slot_used) + \
123 (sizeof(char) * (slots)))
125 static int slots_per_page(struct kprobe_insn_cache
*c
)
127 return PAGE_SIZE
/(c
->insn_size
* sizeof(kprobe_opcode_t
));
130 enum kprobe_slot_state
{
136 static void *alloc_insn_page(void)
138 return module_alloc(PAGE_SIZE
);
141 static void free_insn_page(void *page
)
143 module_free(NULL
, page
);
146 struct kprobe_insn_cache kprobe_insn_slots
= {
147 .mutex
= __MUTEX_INITIALIZER(kprobe_insn_slots
.mutex
),
148 .alloc
= alloc_insn_page
,
149 .free
= free_insn_page
,
150 .pages
= LIST_HEAD_INIT(kprobe_insn_slots
.pages
),
151 .insn_size
= MAX_INSN_SIZE
,
154 static int __kprobes
collect_garbage_slots(struct kprobe_insn_cache
*c
);
157 * __get_insn_slot() - Find a slot on an executable page for an instruction.
158 * We allocate an executable page if there's no room on existing ones.
160 kprobe_opcode_t __kprobes
*__get_insn_slot(struct kprobe_insn_cache
*c
)
162 struct kprobe_insn_page
*kip
;
163 kprobe_opcode_t
*slot
= NULL
;
165 mutex_lock(&c
->mutex
);
167 list_for_each_entry(kip
, &c
->pages
, list
) {
168 if (kip
->nused
< slots_per_page(c
)) {
170 for (i
= 0; i
< slots_per_page(c
); i
++) {
171 if (kip
->slot_used
[i
] == SLOT_CLEAN
) {
172 kip
->slot_used
[i
] = SLOT_USED
;
174 slot
= kip
->insns
+ (i
* c
->insn_size
);
178 /* kip->nused is broken. Fix it. */
179 kip
->nused
= slots_per_page(c
);
184 /* If there are any garbage slots, collect it and try again. */
185 if (c
->nr_garbage
&& collect_garbage_slots(c
) == 0)
188 /* All out of space. Need to allocate a new page. */
189 kip
= kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c
)), GFP_KERNEL
);
194 * Use module_alloc so this page is within +/- 2GB of where the
195 * kernel image and loaded module images reside. This is required
196 * so x86_64 can correctly handle the %rip-relative fixups.
198 kip
->insns
= c
->alloc();
203 INIT_LIST_HEAD(&kip
->list
);
204 memset(kip
->slot_used
, SLOT_CLEAN
, slots_per_page(c
));
205 kip
->slot_used
[0] = SLOT_USED
;
209 list_add(&kip
->list
, &c
->pages
);
212 mutex_unlock(&c
->mutex
);
216 /* Return 1 if all garbages are collected, otherwise 0. */
217 static int __kprobes
collect_one_slot(struct kprobe_insn_page
*kip
, int idx
)
219 kip
->slot_used
[idx
] = SLOT_CLEAN
;
221 if (kip
->nused
== 0) {
223 * Page is no longer in use. Free it unless
224 * it's the last one. We keep the last one
225 * so as not to have to set it up again the
226 * next time somebody inserts a probe.
228 if (!list_is_singular(&kip
->list
)) {
229 list_del(&kip
->list
);
230 kip
->cache
->free(kip
->insns
);
238 static int __kprobes
collect_garbage_slots(struct kprobe_insn_cache
*c
)
240 struct kprobe_insn_page
*kip
, *next
;
242 /* Ensure no-one is interrupted on the garbages */
245 list_for_each_entry_safe(kip
, next
, &c
->pages
, list
) {
247 if (kip
->ngarbage
== 0)
249 kip
->ngarbage
= 0; /* we will collect all garbages */
250 for (i
= 0; i
< slots_per_page(c
); i
++) {
251 if (kip
->slot_used
[i
] == SLOT_DIRTY
&&
252 collect_one_slot(kip
, i
))
260 void __kprobes
__free_insn_slot(struct kprobe_insn_cache
*c
,
261 kprobe_opcode_t
*slot
, int dirty
)
263 struct kprobe_insn_page
*kip
;
265 mutex_lock(&c
->mutex
);
266 list_for_each_entry(kip
, &c
->pages
, list
) {
267 long idx
= ((long)slot
- (long)kip
->insns
) /
268 (c
->insn_size
* sizeof(kprobe_opcode_t
));
269 if (idx
>= 0 && idx
< slots_per_page(c
)) {
270 WARN_ON(kip
->slot_used
[idx
] != SLOT_USED
);
272 kip
->slot_used
[idx
] = SLOT_DIRTY
;
274 if (++c
->nr_garbage
> slots_per_page(c
))
275 collect_garbage_slots(c
);
277 collect_one_slot(kip
, idx
);
281 /* Could not free this slot. */
284 mutex_unlock(&c
->mutex
);
287 #ifdef CONFIG_OPTPROBES
288 /* For optimized_kprobe buffer */
289 struct kprobe_insn_cache kprobe_optinsn_slots
= {
290 .mutex
= __MUTEX_INITIALIZER(kprobe_optinsn_slots
.mutex
),
291 .alloc
= alloc_insn_page
,
292 .free
= free_insn_page
,
293 .pages
= LIST_HEAD_INIT(kprobe_optinsn_slots
.pages
),
294 /* .insn_size is initialized later */
300 /* We have preemption disabled.. so it is safe to use __ versions */
301 static inline void set_kprobe_instance(struct kprobe
*kp
)
303 __this_cpu_write(kprobe_instance
, kp
);
306 static inline void reset_kprobe_instance(void)
308 __this_cpu_write(kprobe_instance
, NULL
);
312 * This routine is called either:
313 * - under the kprobe_mutex - during kprobe_[un]register()
315 * - with preemption disabled - from arch/xxx/kernel/kprobes.c
317 struct kprobe __kprobes
*get_kprobe(void *addr
)
319 struct hlist_head
*head
;
322 head
= &kprobe_table
[hash_ptr(addr
, KPROBE_HASH_BITS
)];
323 hlist_for_each_entry_rcu(p
, head
, hlist
) {
331 static int __kprobes
aggr_pre_handler(struct kprobe
*p
, struct pt_regs
*regs
);
333 /* Return true if the kprobe is an aggregator */
334 static inline int kprobe_aggrprobe(struct kprobe
*p
)
336 return p
->pre_handler
== aggr_pre_handler
;
339 /* Return true(!0) if the kprobe is unused */
340 static inline int kprobe_unused(struct kprobe
*p
)
342 return kprobe_aggrprobe(p
) && kprobe_disabled(p
) &&
343 list_empty(&p
->list
);
347 * Keep all fields in the kprobe consistent
349 static inline void copy_kprobe(struct kprobe
*ap
, struct kprobe
*p
)
351 memcpy(&p
->opcode
, &ap
->opcode
, sizeof(kprobe_opcode_t
));
352 memcpy(&p
->ainsn
, &ap
->ainsn
, sizeof(struct arch_specific_insn
));
355 #ifdef CONFIG_OPTPROBES
356 /* NOTE: change this value only with kprobe_mutex held */
357 static bool kprobes_allow_optimization
;
360 * Call all pre_handler on the list, but ignores its return value.
361 * This must be called from arch-dep optimized caller.
363 void __kprobes
opt_pre_handler(struct kprobe
*p
, struct pt_regs
*regs
)
367 list_for_each_entry_rcu(kp
, &p
->list
, list
) {
368 if (kp
->pre_handler
&& likely(!kprobe_disabled(kp
))) {
369 set_kprobe_instance(kp
);
370 kp
->pre_handler(kp
, regs
);
372 reset_kprobe_instance();
376 /* Free optimized instructions and optimized_kprobe */
377 static __kprobes
void free_aggr_kprobe(struct kprobe
*p
)
379 struct optimized_kprobe
*op
;
381 op
= container_of(p
, struct optimized_kprobe
, kp
);
382 arch_remove_optimized_kprobe(op
);
383 arch_remove_kprobe(p
);
387 /* Return true(!0) if the kprobe is ready for optimization. */
388 static inline int kprobe_optready(struct kprobe
*p
)
390 struct optimized_kprobe
*op
;
392 if (kprobe_aggrprobe(p
)) {
393 op
= container_of(p
, struct optimized_kprobe
, kp
);
394 return arch_prepared_optinsn(&op
->optinsn
);
400 /* Return true(!0) if the kprobe is disarmed. Note: p must be on hash list */
401 static inline int kprobe_disarmed(struct kprobe
*p
)
403 struct optimized_kprobe
*op
;
405 /* If kprobe is not aggr/opt probe, just return kprobe is disabled */
406 if (!kprobe_aggrprobe(p
))
407 return kprobe_disabled(p
);
409 op
= container_of(p
, struct optimized_kprobe
, kp
);
411 return kprobe_disabled(p
) && list_empty(&op
->list
);
414 /* Return true(!0) if the probe is queued on (un)optimizing lists */
415 static int __kprobes
kprobe_queued(struct kprobe
*p
)
417 struct optimized_kprobe
*op
;
419 if (kprobe_aggrprobe(p
)) {
420 op
= container_of(p
, struct optimized_kprobe
, kp
);
421 if (!list_empty(&op
->list
))
428 * Return an optimized kprobe whose optimizing code replaces
429 * instructions including addr (exclude breakpoint).
431 static struct kprobe
*__kprobes
get_optimized_kprobe(unsigned long addr
)
434 struct kprobe
*p
= NULL
;
435 struct optimized_kprobe
*op
;
437 /* Don't check i == 0, since that is a breakpoint case. */
438 for (i
= 1; !p
&& i
< MAX_OPTIMIZED_LENGTH
; i
++)
439 p
= get_kprobe((void *)(addr
- i
));
441 if (p
&& kprobe_optready(p
)) {
442 op
= container_of(p
, struct optimized_kprobe
, kp
);
443 if (arch_within_optimized_kprobe(op
, addr
))
450 /* Optimization staging list, protected by kprobe_mutex */
451 static LIST_HEAD(optimizing_list
);
452 static LIST_HEAD(unoptimizing_list
);
453 static LIST_HEAD(freeing_list
);
455 static void kprobe_optimizer(struct work_struct
*work
);
456 static DECLARE_DELAYED_WORK(optimizing_work
, kprobe_optimizer
);
457 #define OPTIMIZE_DELAY 5
460 * Optimize (replace a breakpoint with a jump) kprobes listed on
463 static __kprobes
void do_optimize_kprobes(void)
465 /* Optimization never be done when disarmed */
466 if (kprobes_all_disarmed
|| !kprobes_allow_optimization
||
467 list_empty(&optimizing_list
))
471 * The optimization/unoptimization refers online_cpus via
472 * stop_machine() and cpu-hotplug modifies online_cpus.
473 * And same time, text_mutex will be held in cpu-hotplug and here.
474 * This combination can cause a deadlock (cpu-hotplug try to lock
475 * text_mutex but stop_machine can not be done because online_cpus
477 * To avoid this deadlock, we need to call get_online_cpus()
478 * for preventing cpu-hotplug outside of text_mutex locking.
481 mutex_lock(&text_mutex
);
482 arch_optimize_kprobes(&optimizing_list
);
483 mutex_unlock(&text_mutex
);
488 * Unoptimize (replace a jump with a breakpoint and remove the breakpoint
489 * if need) kprobes listed on unoptimizing_list.
491 static __kprobes
void do_unoptimize_kprobes(void)
493 struct optimized_kprobe
*op
, *tmp
;
495 /* Unoptimization must be done anytime */
496 if (list_empty(&unoptimizing_list
))
499 /* Ditto to do_optimize_kprobes */
501 mutex_lock(&text_mutex
);
502 arch_unoptimize_kprobes(&unoptimizing_list
, &freeing_list
);
503 /* Loop free_list for disarming */
504 list_for_each_entry_safe(op
, tmp
, &freeing_list
, list
) {
505 /* Disarm probes if marked disabled */
506 if (kprobe_disabled(&op
->kp
))
507 arch_disarm_kprobe(&op
->kp
);
508 if (kprobe_unused(&op
->kp
)) {
510 * Remove unused probes from hash list. After waiting
511 * for synchronization, these probes are reclaimed.
512 * (reclaiming is done by do_free_cleaned_kprobes.)
514 hlist_del_rcu(&op
->kp
.hlist
);
516 list_del_init(&op
->list
);
518 mutex_unlock(&text_mutex
);
522 /* Reclaim all kprobes on the free_list */
523 static __kprobes
void do_free_cleaned_kprobes(void)
525 struct optimized_kprobe
*op
, *tmp
;
527 list_for_each_entry_safe(op
, tmp
, &freeing_list
, list
) {
528 BUG_ON(!kprobe_unused(&op
->kp
));
529 list_del_init(&op
->list
);
530 free_aggr_kprobe(&op
->kp
);
534 /* Start optimizer after OPTIMIZE_DELAY passed */
535 static __kprobes
void kick_kprobe_optimizer(void)
537 schedule_delayed_work(&optimizing_work
, OPTIMIZE_DELAY
);
540 /* Kprobe jump optimizer */
541 static __kprobes
void kprobe_optimizer(struct work_struct
*work
)
543 mutex_lock(&kprobe_mutex
);
544 /* Lock modules while optimizing kprobes */
545 mutex_lock(&module_mutex
);
548 * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
549 * kprobes before waiting for quiesence period.
551 do_unoptimize_kprobes();
554 * Step 2: Wait for quiesence period to ensure all running interrupts
555 * are done. Because optprobe may modify multiple instructions
556 * there is a chance that Nth instruction is interrupted. In that
557 * case, running interrupt can return to 2nd-Nth byte of jump
558 * instruction. This wait is for avoiding it.
562 /* Step 3: Optimize kprobes after quiesence period */
563 do_optimize_kprobes();
565 /* Step 4: Free cleaned kprobes after quiesence period */
566 do_free_cleaned_kprobes();
568 mutex_unlock(&module_mutex
);
569 mutex_unlock(&kprobe_mutex
);
571 /* Step 5: Kick optimizer again if needed */
572 if (!list_empty(&optimizing_list
) || !list_empty(&unoptimizing_list
))
573 kick_kprobe_optimizer();
576 /* Wait for completing optimization and unoptimization */
577 static __kprobes
void wait_for_kprobe_optimizer(void)
579 mutex_lock(&kprobe_mutex
);
581 while (!list_empty(&optimizing_list
) || !list_empty(&unoptimizing_list
)) {
582 mutex_unlock(&kprobe_mutex
);
584 /* this will also make optimizing_work execute immmediately */
585 flush_delayed_work(&optimizing_work
);
586 /* @optimizing_work might not have been queued yet, relax */
589 mutex_lock(&kprobe_mutex
);
592 mutex_unlock(&kprobe_mutex
);
595 /* Optimize kprobe if p is ready to be optimized */
596 static __kprobes
void optimize_kprobe(struct kprobe
*p
)
598 struct optimized_kprobe
*op
;
600 /* Check if the kprobe is disabled or not ready for optimization. */
601 if (!kprobe_optready(p
) || !kprobes_allow_optimization
||
602 (kprobe_disabled(p
) || kprobes_all_disarmed
))
605 /* Both of break_handler and post_handler are not supported. */
606 if (p
->break_handler
|| p
->post_handler
)
609 op
= container_of(p
, struct optimized_kprobe
, kp
);
611 /* Check there is no other kprobes at the optimized instructions */
612 if (arch_check_optimized_kprobe(op
) < 0)
615 /* Check if it is already optimized. */
616 if (op
->kp
.flags
& KPROBE_FLAG_OPTIMIZED
)
618 op
->kp
.flags
|= KPROBE_FLAG_OPTIMIZED
;
620 if (!list_empty(&op
->list
))
621 /* This is under unoptimizing. Just dequeue the probe */
622 list_del_init(&op
->list
);
624 list_add(&op
->list
, &optimizing_list
);
625 kick_kprobe_optimizer();
629 /* Short cut to direct unoptimizing */
630 static __kprobes
void force_unoptimize_kprobe(struct optimized_kprobe
*op
)
633 arch_unoptimize_kprobe(op
);
635 if (kprobe_disabled(&op
->kp
))
636 arch_disarm_kprobe(&op
->kp
);
639 /* Unoptimize a kprobe if p is optimized */
640 static __kprobes
void unoptimize_kprobe(struct kprobe
*p
, bool force
)
642 struct optimized_kprobe
*op
;
644 if (!kprobe_aggrprobe(p
) || kprobe_disarmed(p
))
645 return; /* This is not an optprobe nor optimized */
647 op
= container_of(p
, struct optimized_kprobe
, kp
);
648 if (!kprobe_optimized(p
)) {
649 /* Unoptimized or unoptimizing case */
650 if (force
&& !list_empty(&op
->list
)) {
652 * Only if this is unoptimizing kprobe and forced,
653 * forcibly unoptimize it. (No need to unoptimize
654 * unoptimized kprobe again :)
656 list_del_init(&op
->list
);
657 force_unoptimize_kprobe(op
);
662 op
->kp
.flags
&= ~KPROBE_FLAG_OPTIMIZED
;
663 if (!list_empty(&op
->list
)) {
664 /* Dequeue from the optimization queue */
665 list_del_init(&op
->list
);
668 /* Optimized kprobe case */
670 /* Forcibly update the code: this is a special case */
671 force_unoptimize_kprobe(op
);
673 list_add(&op
->list
, &unoptimizing_list
);
674 kick_kprobe_optimizer();
678 /* Cancel unoptimizing for reusing */
679 static void reuse_unused_kprobe(struct kprobe
*ap
)
681 struct optimized_kprobe
*op
;
683 BUG_ON(!kprobe_unused(ap
));
685 * Unused kprobe MUST be on the way of delayed unoptimizing (means
686 * there is still a relative jump) and disabled.
688 op
= container_of(ap
, struct optimized_kprobe
, kp
);
689 if (unlikely(list_empty(&op
->list
)))
690 printk(KERN_WARNING
"Warning: found a stray unused "
691 "aggrprobe@%p\n", ap
->addr
);
692 /* Enable the probe again */
693 ap
->flags
&= ~KPROBE_FLAG_DISABLED
;
694 /* Optimize it again (remove from op->list) */
695 BUG_ON(!kprobe_optready(ap
));
699 /* Remove optimized instructions */
700 static void __kprobes
kill_optimized_kprobe(struct kprobe
*p
)
702 struct optimized_kprobe
*op
;
704 op
= container_of(p
, struct optimized_kprobe
, kp
);
705 if (!list_empty(&op
->list
))
706 /* Dequeue from the (un)optimization queue */
707 list_del_init(&op
->list
);
708 op
->kp
.flags
&= ~KPROBE_FLAG_OPTIMIZED
;
710 if (kprobe_unused(p
)) {
711 /* Enqueue if it is unused */
712 list_add(&op
->list
, &freeing_list
);
714 * Remove unused probes from the hash list. After waiting
715 * for synchronization, this probe is reclaimed.
716 * (reclaiming is done by do_free_cleaned_kprobes().)
718 hlist_del_rcu(&op
->kp
.hlist
);
721 /* Don't touch the code, because it is already freed. */
722 arch_remove_optimized_kprobe(op
);
725 /* Try to prepare optimized instructions */
726 static __kprobes
void prepare_optimized_kprobe(struct kprobe
*p
)
728 struct optimized_kprobe
*op
;
730 op
= container_of(p
, struct optimized_kprobe
, kp
);
731 arch_prepare_optimized_kprobe(op
);
734 /* Allocate new optimized_kprobe and try to prepare optimized instructions */
735 static __kprobes
struct kprobe
*alloc_aggr_kprobe(struct kprobe
*p
)
737 struct optimized_kprobe
*op
;
739 op
= kzalloc(sizeof(struct optimized_kprobe
), GFP_KERNEL
);
743 INIT_LIST_HEAD(&op
->list
);
744 op
->kp
.addr
= p
->addr
;
745 arch_prepare_optimized_kprobe(op
);
750 static void __kprobes
init_aggr_kprobe(struct kprobe
*ap
, struct kprobe
*p
);
753 * Prepare an optimized_kprobe and optimize it
754 * NOTE: p must be a normal registered kprobe
756 static __kprobes
void try_to_optimize_kprobe(struct kprobe
*p
)
759 struct optimized_kprobe
*op
;
761 /* Impossible to optimize ftrace-based kprobe */
762 if (kprobe_ftrace(p
))
765 /* For preparing optimization, jump_label_text_reserved() is called */
767 mutex_lock(&text_mutex
);
769 ap
= alloc_aggr_kprobe(p
);
773 op
= container_of(ap
, struct optimized_kprobe
, kp
);
774 if (!arch_prepared_optinsn(&op
->optinsn
)) {
775 /* If failed to setup optimizing, fallback to kprobe */
776 arch_remove_optimized_kprobe(op
);
781 init_aggr_kprobe(ap
, p
);
782 optimize_kprobe(ap
); /* This just kicks optimizer thread */
785 mutex_unlock(&text_mutex
);
790 static void __kprobes
optimize_all_kprobes(void)
792 struct hlist_head
*head
;
796 mutex_lock(&kprobe_mutex
);
797 /* If optimization is already allowed, just return */
798 if (kprobes_allow_optimization
)
801 kprobes_allow_optimization
= true;
802 for (i
= 0; i
< KPROBE_TABLE_SIZE
; i
++) {
803 head
= &kprobe_table
[i
];
804 hlist_for_each_entry_rcu(p
, head
, hlist
)
805 if (!kprobe_disabled(p
))
808 printk(KERN_INFO
"Kprobes globally optimized\n");
810 mutex_unlock(&kprobe_mutex
);
813 static void __kprobes
unoptimize_all_kprobes(void)
815 struct hlist_head
*head
;
819 mutex_lock(&kprobe_mutex
);
820 /* If optimization is already prohibited, just return */
821 if (!kprobes_allow_optimization
) {
822 mutex_unlock(&kprobe_mutex
);
826 kprobes_allow_optimization
= false;
827 for (i
= 0; i
< KPROBE_TABLE_SIZE
; i
++) {
828 head
= &kprobe_table
[i
];
829 hlist_for_each_entry_rcu(p
, head
, hlist
) {
830 if (!kprobe_disabled(p
))
831 unoptimize_kprobe(p
, false);
834 mutex_unlock(&kprobe_mutex
);
836 /* Wait for unoptimizing completion */
837 wait_for_kprobe_optimizer();
838 printk(KERN_INFO
"Kprobes globally unoptimized\n");
841 static DEFINE_MUTEX(kprobe_sysctl_mutex
);
842 int sysctl_kprobes_optimization
;
843 int proc_kprobes_optimization_handler(struct ctl_table
*table
, int write
,
844 void __user
*buffer
, size_t *length
,
849 mutex_lock(&kprobe_sysctl_mutex
);
850 sysctl_kprobes_optimization
= kprobes_allow_optimization
? 1 : 0;
851 ret
= proc_dointvec_minmax(table
, write
, buffer
, length
, ppos
);
853 if (sysctl_kprobes_optimization
)
854 optimize_all_kprobes();
856 unoptimize_all_kprobes();
857 mutex_unlock(&kprobe_sysctl_mutex
);
861 #endif /* CONFIG_SYSCTL */
863 /* Put a breakpoint for a probe. Must be called with text_mutex locked */
864 static void __kprobes
__arm_kprobe(struct kprobe
*p
)
868 /* Check collision with other optimized kprobes */
869 _p
= get_optimized_kprobe((unsigned long)p
->addr
);
871 /* Fallback to unoptimized kprobe */
872 unoptimize_kprobe(_p
, true);
875 optimize_kprobe(p
); /* Try to optimize (add kprobe to a list) */
878 /* Remove the breakpoint of a probe. Must be called with text_mutex locked */
879 static void __kprobes
__disarm_kprobe(struct kprobe
*p
, bool reopt
)
883 unoptimize_kprobe(p
, false); /* Try to unoptimize */
885 if (!kprobe_queued(p
)) {
886 arch_disarm_kprobe(p
);
887 /* If another kprobe was blocked, optimize it. */
888 _p
= get_optimized_kprobe((unsigned long)p
->addr
);
889 if (unlikely(_p
) && reopt
)
892 /* TODO: reoptimize others after unoptimized this probe */
895 #else /* !CONFIG_OPTPROBES */
897 #define optimize_kprobe(p) do {} while (0)
898 #define unoptimize_kprobe(p, f) do {} while (0)
899 #define kill_optimized_kprobe(p) do {} while (0)
900 #define prepare_optimized_kprobe(p) do {} while (0)
901 #define try_to_optimize_kprobe(p) do {} while (0)
902 #define __arm_kprobe(p) arch_arm_kprobe(p)
903 #define __disarm_kprobe(p, o) arch_disarm_kprobe(p)
904 #define kprobe_disarmed(p) kprobe_disabled(p)
905 #define wait_for_kprobe_optimizer() do {} while (0)
907 /* There should be no unused kprobes can be reused without optimization */
908 static void reuse_unused_kprobe(struct kprobe
*ap
)
910 printk(KERN_ERR
"Error: There should be no unused kprobe here.\n");
911 BUG_ON(kprobe_unused(ap
));
914 static __kprobes
void free_aggr_kprobe(struct kprobe
*p
)
916 arch_remove_kprobe(p
);
920 static __kprobes
struct kprobe
*alloc_aggr_kprobe(struct kprobe
*p
)
922 return kzalloc(sizeof(struct kprobe
), GFP_KERNEL
);
924 #endif /* CONFIG_OPTPROBES */
926 #ifdef CONFIG_KPROBES_ON_FTRACE
927 static struct ftrace_ops kprobe_ftrace_ops __read_mostly
= {
928 .func
= kprobe_ftrace_handler
,
929 .flags
= FTRACE_OPS_FL_SAVE_REGS
,
931 static int kprobe_ftrace_enabled
;
933 /* Must ensure p->addr is really on ftrace */
934 static int __kprobes
prepare_kprobe(struct kprobe
*p
)
936 if (!kprobe_ftrace(p
))
937 return arch_prepare_kprobe(p
);
939 return arch_prepare_kprobe_ftrace(p
);
942 /* Caller must lock kprobe_mutex */
943 static void __kprobes
arm_kprobe_ftrace(struct kprobe
*p
)
947 ret
= ftrace_set_filter_ip(&kprobe_ftrace_ops
,
948 (unsigned long)p
->addr
, 0, 0);
949 WARN(ret
< 0, "Failed to arm kprobe-ftrace at %p (%d)\n", p
->addr
, ret
);
950 kprobe_ftrace_enabled
++;
951 if (kprobe_ftrace_enabled
== 1) {
952 ret
= register_ftrace_function(&kprobe_ftrace_ops
);
953 WARN(ret
< 0, "Failed to init kprobe-ftrace (%d)\n", ret
);
957 /* Caller must lock kprobe_mutex */
958 static void __kprobes
disarm_kprobe_ftrace(struct kprobe
*p
)
962 kprobe_ftrace_enabled
--;
963 if (kprobe_ftrace_enabled
== 0) {
964 ret
= unregister_ftrace_function(&kprobe_ftrace_ops
);
965 WARN(ret
< 0, "Failed to init kprobe-ftrace (%d)\n", ret
);
967 ret
= ftrace_set_filter_ip(&kprobe_ftrace_ops
,
968 (unsigned long)p
->addr
, 1, 0);
969 WARN(ret
< 0, "Failed to disarm kprobe-ftrace at %p (%d)\n", p
->addr
, ret
);
971 #else /* !CONFIG_KPROBES_ON_FTRACE */
972 #define prepare_kprobe(p) arch_prepare_kprobe(p)
973 #define arm_kprobe_ftrace(p) do {} while (0)
974 #define disarm_kprobe_ftrace(p) do {} while (0)
977 /* Arm a kprobe with text_mutex */
978 static void __kprobes
arm_kprobe(struct kprobe
*kp
)
980 if (unlikely(kprobe_ftrace(kp
))) {
981 arm_kprobe_ftrace(kp
);
985 * Here, since __arm_kprobe() doesn't use stop_machine(),
986 * this doesn't cause deadlock on text_mutex. So, we don't
987 * need get_online_cpus().
989 mutex_lock(&text_mutex
);
991 mutex_unlock(&text_mutex
);
994 /* Disarm a kprobe with text_mutex */
995 static void __kprobes
disarm_kprobe(struct kprobe
*kp
, bool reopt
)
997 if (unlikely(kprobe_ftrace(kp
))) {
998 disarm_kprobe_ftrace(kp
);
1002 mutex_lock(&text_mutex
);
1003 __disarm_kprobe(kp
, reopt
);
1004 mutex_unlock(&text_mutex
);
1008 * Aggregate handlers for multiple kprobes support - these handlers
1009 * take care of invoking the individual kprobe handlers on p->list
1011 static int __kprobes
aggr_pre_handler(struct kprobe
*p
, struct pt_regs
*regs
)
1015 list_for_each_entry_rcu(kp
, &p
->list
, list
) {
1016 if (kp
->pre_handler
&& likely(!kprobe_disabled(kp
))) {
1017 set_kprobe_instance(kp
);
1018 if (kp
->pre_handler(kp
, regs
))
1021 reset_kprobe_instance();
1026 static void __kprobes
aggr_post_handler(struct kprobe
*p
, struct pt_regs
*regs
,
1027 unsigned long flags
)
1031 list_for_each_entry_rcu(kp
, &p
->list
, list
) {
1032 if (kp
->post_handler
&& likely(!kprobe_disabled(kp
))) {
1033 set_kprobe_instance(kp
);
1034 kp
->post_handler(kp
, regs
, flags
);
1035 reset_kprobe_instance();
1040 static int __kprobes
aggr_fault_handler(struct kprobe
*p
, struct pt_regs
*regs
,
1043 struct kprobe
*cur
= __this_cpu_read(kprobe_instance
);
1046 * if we faulted "during" the execution of a user specified
1047 * probe handler, invoke just that probe's fault handler
1049 if (cur
&& cur
->fault_handler
) {
1050 if (cur
->fault_handler(cur
, regs
, trapnr
))
1056 static int __kprobes
aggr_break_handler(struct kprobe
*p
, struct pt_regs
*regs
)
1058 struct kprobe
*cur
= __this_cpu_read(kprobe_instance
);
1061 if (cur
&& cur
->break_handler
) {
1062 if (cur
->break_handler(cur
, regs
))
1065 reset_kprobe_instance();
1069 /* Walks the list and increments nmissed count for multiprobe case */
1070 void __kprobes
kprobes_inc_nmissed_count(struct kprobe
*p
)
1073 if (!kprobe_aggrprobe(p
)) {
1076 list_for_each_entry_rcu(kp
, &p
->list
, list
)
1082 void __kprobes
recycle_rp_inst(struct kretprobe_instance
*ri
,
1083 struct hlist_head
*head
)
1085 struct kretprobe
*rp
= ri
->rp
;
1087 /* remove rp inst off the rprobe_inst_table */
1088 hlist_del(&ri
->hlist
);
1089 INIT_HLIST_NODE(&ri
->hlist
);
1091 raw_spin_lock(&rp
->lock
);
1092 hlist_add_head(&ri
->hlist
, &rp
->free_instances
);
1093 raw_spin_unlock(&rp
->lock
);
1096 hlist_add_head(&ri
->hlist
, head
);
1099 void __kprobes
kretprobe_hash_lock(struct task_struct
*tsk
,
1100 struct hlist_head
**head
, unsigned long *flags
)
1101 __acquires(hlist_lock
)
1103 unsigned long hash
= hash_ptr(tsk
, KPROBE_HASH_BITS
);
1104 raw_spinlock_t
*hlist_lock
;
1106 *head
= &kretprobe_inst_table
[hash
];
1107 hlist_lock
= kretprobe_table_lock_ptr(hash
);
1108 raw_spin_lock_irqsave(hlist_lock
, *flags
);
1111 static void __kprobes
kretprobe_table_lock(unsigned long hash
,
1112 unsigned long *flags
)
1113 __acquires(hlist_lock
)
1115 raw_spinlock_t
*hlist_lock
= kretprobe_table_lock_ptr(hash
);
1116 raw_spin_lock_irqsave(hlist_lock
, *flags
);
1119 void __kprobes
kretprobe_hash_unlock(struct task_struct
*tsk
,
1120 unsigned long *flags
)
1121 __releases(hlist_lock
)
1123 unsigned long hash
= hash_ptr(tsk
, KPROBE_HASH_BITS
);
1124 raw_spinlock_t
*hlist_lock
;
1126 hlist_lock
= kretprobe_table_lock_ptr(hash
);
1127 raw_spin_unlock_irqrestore(hlist_lock
, *flags
);
1130 static void __kprobes
kretprobe_table_unlock(unsigned long hash
,
1131 unsigned long *flags
)
1132 __releases(hlist_lock
)
1134 raw_spinlock_t
*hlist_lock
= kretprobe_table_lock_ptr(hash
);
1135 raw_spin_unlock_irqrestore(hlist_lock
, *flags
);
1139 * This function is called from finish_task_switch when task tk becomes dead,
1140 * so that we can recycle any function-return probe instances associated
1141 * with this task. These left over instances represent probed functions
1142 * that have been called but will never return.
1144 void __kprobes
kprobe_flush_task(struct task_struct
*tk
)
1146 struct kretprobe_instance
*ri
;
1147 struct hlist_head
*head
, empty_rp
;
1148 struct hlist_node
*tmp
;
1149 unsigned long hash
, flags
= 0;
1151 if (unlikely(!kprobes_initialized
))
1152 /* Early boot. kretprobe_table_locks not yet initialized. */
1155 INIT_HLIST_HEAD(&empty_rp
);
1156 hash
= hash_ptr(tk
, KPROBE_HASH_BITS
);
1157 head
= &kretprobe_inst_table
[hash
];
1158 kretprobe_table_lock(hash
, &flags
);
1159 hlist_for_each_entry_safe(ri
, tmp
, head
, hlist
) {
1161 recycle_rp_inst(ri
, &empty_rp
);
1163 kretprobe_table_unlock(hash
, &flags
);
1164 hlist_for_each_entry_safe(ri
, tmp
, &empty_rp
, hlist
) {
1165 hlist_del(&ri
->hlist
);
1170 static inline void free_rp_inst(struct kretprobe
*rp
)
1172 struct kretprobe_instance
*ri
;
1173 struct hlist_node
*next
;
1175 hlist_for_each_entry_safe(ri
, next
, &rp
->free_instances
, hlist
) {
1176 hlist_del(&ri
->hlist
);
1181 static void __kprobes
cleanup_rp_inst(struct kretprobe
*rp
)
1183 unsigned long flags
, hash
;
1184 struct kretprobe_instance
*ri
;
1185 struct hlist_node
*next
;
1186 struct hlist_head
*head
;
1189 for (hash
= 0; hash
< KPROBE_TABLE_SIZE
; hash
++) {
1190 kretprobe_table_lock(hash
, &flags
);
1191 head
= &kretprobe_inst_table
[hash
];
1192 hlist_for_each_entry_safe(ri
, next
, head
, hlist
) {
1196 kretprobe_table_unlock(hash
, &flags
);
1202 * Add the new probe to ap->list. Fail if this is the
1203 * second jprobe at the address - two jprobes can't coexist
1205 static int __kprobes
add_new_kprobe(struct kprobe
*ap
, struct kprobe
*p
)
1207 BUG_ON(kprobe_gone(ap
) || kprobe_gone(p
));
1209 if (p
->break_handler
|| p
->post_handler
)
1210 unoptimize_kprobe(ap
, true); /* Fall back to normal kprobe */
1212 if (p
->break_handler
) {
1213 if (ap
->break_handler
)
1215 list_add_tail_rcu(&p
->list
, &ap
->list
);
1216 ap
->break_handler
= aggr_break_handler
;
1218 list_add_rcu(&p
->list
, &ap
->list
);
1219 if (p
->post_handler
&& !ap
->post_handler
)
1220 ap
->post_handler
= aggr_post_handler
;
1226 * Fill in the required fields of the "manager kprobe". Replace the
1227 * earlier kprobe in the hlist with the manager kprobe
1229 static void __kprobes
init_aggr_kprobe(struct kprobe
*ap
, struct kprobe
*p
)
1231 /* Copy p's insn slot to ap */
1233 flush_insn_slot(ap
);
1235 ap
->flags
= p
->flags
& ~KPROBE_FLAG_OPTIMIZED
;
1236 ap
->pre_handler
= aggr_pre_handler
;
1237 ap
->fault_handler
= aggr_fault_handler
;
1238 /* We don't care the kprobe which has gone. */
1239 if (p
->post_handler
&& !kprobe_gone(p
))
1240 ap
->post_handler
= aggr_post_handler
;
1241 if (p
->break_handler
&& !kprobe_gone(p
))
1242 ap
->break_handler
= aggr_break_handler
;
1244 INIT_LIST_HEAD(&ap
->list
);
1245 INIT_HLIST_NODE(&ap
->hlist
);
1247 list_add_rcu(&p
->list
, &ap
->list
);
1248 hlist_replace_rcu(&p
->hlist
, &ap
->hlist
);
1252 * This is the second or subsequent kprobe at the address - handle
1255 static int __kprobes
register_aggr_kprobe(struct kprobe
*orig_p
,
1259 struct kprobe
*ap
= orig_p
;
1261 /* For preparing optimization, jump_label_text_reserved() is called */
1264 * Get online CPUs to avoid text_mutex deadlock.with stop machine,
1265 * which is invoked by unoptimize_kprobe() in add_new_kprobe()
1268 mutex_lock(&text_mutex
);
1270 if (!kprobe_aggrprobe(orig_p
)) {
1271 /* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */
1272 ap
= alloc_aggr_kprobe(orig_p
);
1277 init_aggr_kprobe(ap
, orig_p
);
1278 } else if (kprobe_unused(ap
))
1279 /* This probe is going to die. Rescue it */
1280 reuse_unused_kprobe(ap
);
1282 if (kprobe_gone(ap
)) {
1284 * Attempting to insert new probe at the same location that
1285 * had a probe in the module vaddr area which already
1286 * freed. So, the instruction slot has already been
1287 * released. We need a new slot for the new probe.
1289 ret
= arch_prepare_kprobe(ap
);
1292 * Even if fail to allocate new slot, don't need to
1293 * free aggr_probe. It will be used next time, or
1294 * freed by unregister_kprobe.
1298 /* Prepare optimized instructions if possible. */
1299 prepare_optimized_kprobe(ap
);
1302 * Clear gone flag to prevent allocating new slot again, and
1303 * set disabled flag because it is not armed yet.
1305 ap
->flags
= (ap
->flags
& ~KPROBE_FLAG_GONE
)
1306 | KPROBE_FLAG_DISABLED
;
1309 /* Copy ap's insn slot to p */
1311 ret
= add_new_kprobe(ap
, p
);
1314 mutex_unlock(&text_mutex
);
1316 jump_label_unlock();
1318 if (ret
== 0 && kprobe_disabled(ap
) && !kprobe_disabled(p
)) {
1319 ap
->flags
&= ~KPROBE_FLAG_DISABLED
;
1320 if (!kprobes_all_disarmed
)
1321 /* Arm the breakpoint again. */
1327 static int __kprobes
in_kprobes_functions(unsigned long addr
)
1329 struct kprobe_blackpoint
*kb
;
1331 if (addr
>= (unsigned long)__kprobes_text_start
&&
1332 addr
< (unsigned long)__kprobes_text_end
)
1335 * If there exists a kprobe_blacklist, verify and
1336 * fail any probe registration in the prohibited area
1338 for (kb
= kprobe_blacklist
; kb
->name
!= NULL
; kb
++) {
1339 if (kb
->start_addr
) {
1340 if (addr
>= kb
->start_addr
&&
1341 addr
< (kb
->start_addr
+ kb
->range
))
1349 * If we have a symbol_name argument, look it up and add the offset field
1350 * to it. This way, we can specify a relative address to a symbol.
1351 * This returns encoded errors if it fails to look up symbol or invalid
1352 * combination of parameters.
1354 static kprobe_opcode_t __kprobes
*kprobe_addr(struct kprobe
*p
)
1356 kprobe_opcode_t
*addr
= p
->addr
;
1358 if ((p
->symbol_name
&& p
->addr
) ||
1359 (!p
->symbol_name
&& !p
->addr
))
1362 if (p
->symbol_name
) {
1363 kprobe_lookup_name(p
->symbol_name
, addr
);
1365 return ERR_PTR(-ENOENT
);
1368 addr
= (kprobe_opcode_t
*)(((char *)addr
) + p
->offset
);
1373 return ERR_PTR(-EINVAL
);
1376 /* Check passed kprobe is valid and return kprobe in kprobe_table. */
1377 static struct kprobe
* __kprobes
__get_valid_kprobe(struct kprobe
*p
)
1379 struct kprobe
*ap
, *list_p
;
1381 ap
= get_kprobe(p
->addr
);
1386 list_for_each_entry_rcu(list_p
, &ap
->list
, list
)
1388 /* kprobe p is a valid probe */
1396 /* Return error if the kprobe is being re-registered */
1397 static inline int check_kprobe_rereg(struct kprobe
*p
)
1401 mutex_lock(&kprobe_mutex
);
1402 if (__get_valid_kprobe(p
))
1404 mutex_unlock(&kprobe_mutex
);
1409 static __kprobes
int check_kprobe_address_safe(struct kprobe
*p
,
1410 struct module
**probed_mod
)
1413 unsigned long ftrace_addr
;
1416 * If the address is located on a ftrace nop, set the
1417 * breakpoint to the following instruction.
1419 ftrace_addr
= ftrace_location((unsigned long)p
->addr
);
1421 #ifdef CONFIG_KPROBES_ON_FTRACE
1422 /* Given address is not on the instruction boundary */
1423 if ((unsigned long)p
->addr
!= ftrace_addr
)
1425 p
->flags
|= KPROBE_FLAG_FTRACE
;
1426 #else /* !CONFIG_KPROBES_ON_FTRACE */
1434 /* Ensure it is not in reserved area nor out of text */
1435 if (!kernel_text_address((unsigned long) p
->addr
) ||
1436 in_kprobes_functions((unsigned long) p
->addr
) ||
1437 jump_label_text_reserved(p
->addr
, p
->addr
)) {
1442 /* Check if are we probing a module */
1443 *probed_mod
= __module_text_address((unsigned long) p
->addr
);
1446 * We must hold a refcount of the probed module while updating
1447 * its code to prohibit unexpected unloading.
1449 if (unlikely(!try_module_get(*probed_mod
))) {
1455 * If the module freed .init.text, we couldn't insert
1458 if (within_module_init((unsigned long)p
->addr
, *probed_mod
) &&
1459 (*probed_mod
)->state
!= MODULE_STATE_COMING
) {
1460 module_put(*probed_mod
);
1467 jump_label_unlock();
1472 int __kprobes
register_kprobe(struct kprobe
*p
)
1475 struct kprobe
*old_p
;
1476 struct module
*probed_mod
;
1477 kprobe_opcode_t
*addr
;
1479 /* Adjust probe address from symbol */
1480 addr
= kprobe_addr(p
);
1482 return PTR_ERR(addr
);
1485 ret
= check_kprobe_rereg(p
);
1489 /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
1490 p
->flags
&= KPROBE_FLAG_DISABLED
;
1492 INIT_LIST_HEAD(&p
->list
);
1494 ret
= check_kprobe_address_safe(p
, &probed_mod
);
1498 mutex_lock(&kprobe_mutex
);
1500 old_p
= get_kprobe(p
->addr
);
1502 /* Since this may unoptimize old_p, locking text_mutex. */
1503 ret
= register_aggr_kprobe(old_p
, p
);
1507 mutex_lock(&text_mutex
); /* Avoiding text modification */
1508 ret
= prepare_kprobe(p
);
1509 mutex_unlock(&text_mutex
);
1513 INIT_HLIST_NODE(&p
->hlist
);
1514 hlist_add_head_rcu(&p
->hlist
,
1515 &kprobe_table
[hash_ptr(p
->addr
, KPROBE_HASH_BITS
)]);
1517 if (!kprobes_all_disarmed
&& !kprobe_disabled(p
))
1520 /* Try to optimize kprobe */
1521 try_to_optimize_kprobe(p
);
1524 mutex_unlock(&kprobe_mutex
);
1527 module_put(probed_mod
);
1531 EXPORT_SYMBOL_GPL(register_kprobe
);
1533 /* Check if all probes on the aggrprobe are disabled */
1534 static int __kprobes
aggr_kprobe_disabled(struct kprobe
*ap
)
1538 list_for_each_entry_rcu(kp
, &ap
->list
, list
)
1539 if (!kprobe_disabled(kp
))
1541 * There is an active probe on the list.
1542 * We can't disable this ap.
1549 /* Disable one kprobe: Make sure called under kprobe_mutex is locked */
1550 static struct kprobe
*__kprobes
__disable_kprobe(struct kprobe
*p
)
1552 struct kprobe
*orig_p
;
1554 /* Get an original kprobe for return */
1555 orig_p
= __get_valid_kprobe(p
);
1556 if (unlikely(orig_p
== NULL
))
1559 if (!kprobe_disabled(p
)) {
1560 /* Disable probe if it is a child probe */
1562 p
->flags
|= KPROBE_FLAG_DISABLED
;
1564 /* Try to disarm and disable this/parent probe */
1565 if (p
== orig_p
|| aggr_kprobe_disabled(orig_p
)) {
1566 disarm_kprobe(orig_p
, true);
1567 orig_p
->flags
|= KPROBE_FLAG_DISABLED
;
1575 * Unregister a kprobe without a scheduler synchronization.
1577 static int __kprobes
__unregister_kprobe_top(struct kprobe
*p
)
1579 struct kprobe
*ap
, *list_p
;
1581 /* Disable kprobe. This will disarm it if needed. */
1582 ap
= __disable_kprobe(p
);
1588 * This probe is an independent(and non-optimized) kprobe
1589 * (not an aggrprobe). Remove from the hash list.
1593 /* Following process expects this probe is an aggrprobe */
1594 WARN_ON(!kprobe_aggrprobe(ap
));
1596 if (list_is_singular(&ap
->list
) && kprobe_disarmed(ap
))
1598 * !disarmed could be happen if the probe is under delayed
1603 /* If disabling probe has special handlers, update aggrprobe */
1604 if (p
->break_handler
&& !kprobe_gone(p
))
1605 ap
->break_handler
= NULL
;
1606 if (p
->post_handler
&& !kprobe_gone(p
)) {
1607 list_for_each_entry_rcu(list_p
, &ap
->list
, list
) {
1608 if ((list_p
!= p
) && (list_p
->post_handler
))
1611 ap
->post_handler
= NULL
;
1615 * Remove from the aggrprobe: this path will do nothing in
1616 * __unregister_kprobe_bottom().
1618 list_del_rcu(&p
->list
);
1619 if (!kprobe_disabled(ap
) && !kprobes_all_disarmed
)
1621 * Try to optimize this probe again, because post
1622 * handler may have been changed.
1624 optimize_kprobe(ap
);
1629 BUG_ON(!kprobe_disarmed(ap
));
1630 hlist_del_rcu(&ap
->hlist
);
1634 static void __kprobes
__unregister_kprobe_bottom(struct kprobe
*p
)
1638 if (list_empty(&p
->list
))
1639 /* This is an independent kprobe */
1640 arch_remove_kprobe(p
);
1641 else if (list_is_singular(&p
->list
)) {
1642 /* This is the last child of an aggrprobe */
1643 ap
= list_entry(p
->list
.next
, struct kprobe
, list
);
1645 free_aggr_kprobe(ap
);
1647 /* Otherwise, do nothing. */
1650 int __kprobes
register_kprobes(struct kprobe
**kps
, int num
)
1656 for (i
= 0; i
< num
; i
++) {
1657 ret
= register_kprobe(kps
[i
]);
1660 unregister_kprobes(kps
, i
);
1666 EXPORT_SYMBOL_GPL(register_kprobes
);
1668 void __kprobes
unregister_kprobe(struct kprobe
*p
)
1670 unregister_kprobes(&p
, 1);
1672 EXPORT_SYMBOL_GPL(unregister_kprobe
);
1674 void __kprobes
unregister_kprobes(struct kprobe
**kps
, int num
)
1680 mutex_lock(&kprobe_mutex
);
1681 for (i
= 0; i
< num
; i
++)
1682 if (__unregister_kprobe_top(kps
[i
]) < 0)
1683 kps
[i
]->addr
= NULL
;
1684 mutex_unlock(&kprobe_mutex
);
1686 synchronize_sched();
1687 for (i
= 0; i
< num
; i
++)
1689 __unregister_kprobe_bottom(kps
[i
]);
1691 EXPORT_SYMBOL_GPL(unregister_kprobes
);
1693 static struct notifier_block kprobe_exceptions_nb
= {
1694 .notifier_call
= kprobe_exceptions_notify
,
1695 .priority
= 0x7fffffff /* we need to be notified first */
1698 unsigned long __weak
arch_deref_entry_point(void *entry
)
1700 return (unsigned long)entry
;
1703 int __kprobes
register_jprobes(struct jprobe
**jps
, int num
)
1710 for (i
= 0; i
< num
; i
++) {
1711 unsigned long addr
, offset
;
1713 addr
= arch_deref_entry_point(jp
->entry
);
1715 /* Verify probepoint is a function entry point */
1716 if (kallsyms_lookup_size_offset(addr
, NULL
, &offset
) &&
1718 jp
->kp
.pre_handler
= setjmp_pre_handler
;
1719 jp
->kp
.break_handler
= longjmp_break_handler
;
1720 ret
= register_kprobe(&jp
->kp
);
1726 unregister_jprobes(jps
, i
);
1732 EXPORT_SYMBOL_GPL(register_jprobes
);
1734 int __kprobes
register_jprobe(struct jprobe
*jp
)
1736 return register_jprobes(&jp
, 1);
1738 EXPORT_SYMBOL_GPL(register_jprobe
);
1740 void __kprobes
unregister_jprobe(struct jprobe
*jp
)
1742 unregister_jprobes(&jp
, 1);
1744 EXPORT_SYMBOL_GPL(unregister_jprobe
);
1746 void __kprobes
unregister_jprobes(struct jprobe
**jps
, int num
)
1752 mutex_lock(&kprobe_mutex
);
1753 for (i
= 0; i
< num
; i
++)
1754 if (__unregister_kprobe_top(&jps
[i
]->kp
) < 0)
1755 jps
[i
]->kp
.addr
= NULL
;
1756 mutex_unlock(&kprobe_mutex
);
1758 synchronize_sched();
1759 for (i
= 0; i
< num
; i
++) {
1760 if (jps
[i
]->kp
.addr
)
1761 __unregister_kprobe_bottom(&jps
[i
]->kp
);
1764 EXPORT_SYMBOL_GPL(unregister_jprobes
);
1766 #ifdef CONFIG_KRETPROBES
1768 * This kprobe pre_handler is registered with every kretprobe. When probe
1769 * hits it will set up the return probe.
1771 static int __kprobes
pre_handler_kretprobe(struct kprobe
*p
,
1772 struct pt_regs
*regs
)
1774 struct kretprobe
*rp
= container_of(p
, struct kretprobe
, kp
);
1775 unsigned long hash
, flags
= 0;
1776 struct kretprobe_instance
*ri
;
1778 /*TODO: consider to only swap the RA after the last pre_handler fired */
1779 hash
= hash_ptr(current
, KPROBE_HASH_BITS
);
1780 raw_spin_lock_irqsave(&rp
->lock
, flags
);
1781 if (!hlist_empty(&rp
->free_instances
)) {
1782 ri
= hlist_entry(rp
->free_instances
.first
,
1783 struct kretprobe_instance
, hlist
);
1784 hlist_del(&ri
->hlist
);
1785 raw_spin_unlock_irqrestore(&rp
->lock
, flags
);
1790 if (rp
->entry_handler
&& rp
->entry_handler(ri
, regs
)) {
1791 raw_spin_lock_irqsave(&rp
->lock
, flags
);
1792 hlist_add_head(&ri
->hlist
, &rp
->free_instances
);
1793 raw_spin_unlock_irqrestore(&rp
->lock
, flags
);
1797 arch_prepare_kretprobe(ri
, regs
);
1799 /* XXX(hch): why is there no hlist_move_head? */
1800 INIT_HLIST_NODE(&ri
->hlist
);
1801 kretprobe_table_lock(hash
, &flags
);
1802 hlist_add_head(&ri
->hlist
, &kretprobe_inst_table
[hash
]);
1803 kretprobe_table_unlock(hash
, &flags
);
1806 raw_spin_unlock_irqrestore(&rp
->lock
, flags
);
1811 int __kprobes
register_kretprobe(struct kretprobe
*rp
)
1814 struct kretprobe_instance
*inst
;
1818 if (kretprobe_blacklist_size
) {
1819 addr
= kprobe_addr(&rp
->kp
);
1821 return PTR_ERR(addr
);
1823 for (i
= 0; kretprobe_blacklist
[i
].name
!= NULL
; i
++) {
1824 if (kretprobe_blacklist
[i
].addr
== addr
)
1829 rp
->kp
.pre_handler
= pre_handler_kretprobe
;
1830 rp
->kp
.post_handler
= NULL
;
1831 rp
->kp
.fault_handler
= NULL
;
1832 rp
->kp
.break_handler
= NULL
;
1834 /* Pre-allocate memory for max kretprobe instances */
1835 if (rp
->maxactive
<= 0) {
1836 #ifdef CONFIG_PREEMPT
1837 rp
->maxactive
= max_t(unsigned int, 10, 2*num_possible_cpus());
1839 rp
->maxactive
= num_possible_cpus();
1842 raw_spin_lock_init(&rp
->lock
);
1843 INIT_HLIST_HEAD(&rp
->free_instances
);
1844 for (i
= 0; i
< rp
->maxactive
; i
++) {
1845 inst
= kmalloc(sizeof(struct kretprobe_instance
) +
1846 rp
->data_size
, GFP_KERNEL
);
1851 INIT_HLIST_NODE(&inst
->hlist
);
1852 hlist_add_head(&inst
->hlist
, &rp
->free_instances
);
1856 /* Establish function entry probe point */
1857 ret
= register_kprobe(&rp
->kp
);
1862 EXPORT_SYMBOL_GPL(register_kretprobe
);
1864 int __kprobes
register_kretprobes(struct kretprobe
**rps
, int num
)
1870 for (i
= 0; i
< num
; i
++) {
1871 ret
= register_kretprobe(rps
[i
]);
1874 unregister_kretprobes(rps
, i
);
1880 EXPORT_SYMBOL_GPL(register_kretprobes
);
1882 void __kprobes
unregister_kretprobe(struct kretprobe
*rp
)
1884 unregister_kretprobes(&rp
, 1);
1886 EXPORT_SYMBOL_GPL(unregister_kretprobe
);
1888 void __kprobes
unregister_kretprobes(struct kretprobe
**rps
, int num
)
1894 mutex_lock(&kprobe_mutex
);
1895 for (i
= 0; i
< num
; i
++)
1896 if (__unregister_kprobe_top(&rps
[i
]->kp
) < 0)
1897 rps
[i
]->kp
.addr
= NULL
;
1898 mutex_unlock(&kprobe_mutex
);
1900 synchronize_sched();
1901 for (i
= 0; i
< num
; i
++) {
1902 if (rps
[i
]->kp
.addr
) {
1903 __unregister_kprobe_bottom(&rps
[i
]->kp
);
1904 cleanup_rp_inst(rps
[i
]);
1908 EXPORT_SYMBOL_GPL(unregister_kretprobes
);
1910 #else /* CONFIG_KRETPROBES */
1911 int __kprobes
register_kretprobe(struct kretprobe
*rp
)
1915 EXPORT_SYMBOL_GPL(register_kretprobe
);
1917 int __kprobes
register_kretprobes(struct kretprobe
**rps
, int num
)
1921 EXPORT_SYMBOL_GPL(register_kretprobes
);
1923 void __kprobes
unregister_kretprobe(struct kretprobe
*rp
)
1926 EXPORT_SYMBOL_GPL(unregister_kretprobe
);
1928 void __kprobes
unregister_kretprobes(struct kretprobe
**rps
, int num
)
1931 EXPORT_SYMBOL_GPL(unregister_kretprobes
);
1933 static int __kprobes
pre_handler_kretprobe(struct kprobe
*p
,
1934 struct pt_regs
*regs
)
1939 #endif /* CONFIG_KRETPROBES */
1941 /* Set the kprobe gone and remove its instruction buffer. */
1942 static void __kprobes
kill_kprobe(struct kprobe
*p
)
1946 p
->flags
|= KPROBE_FLAG_GONE
;
1947 if (kprobe_aggrprobe(p
)) {
1949 * If this is an aggr_kprobe, we have to list all the
1950 * chained probes and mark them GONE.
1952 list_for_each_entry_rcu(kp
, &p
->list
, list
)
1953 kp
->flags
|= KPROBE_FLAG_GONE
;
1954 p
->post_handler
= NULL
;
1955 p
->break_handler
= NULL
;
1956 kill_optimized_kprobe(p
);
1959 * Here, we can remove insn_slot safely, because no thread calls
1960 * the original probed function (which will be freed soon) any more.
1962 arch_remove_kprobe(p
);
1965 /* Disable one kprobe */
1966 int __kprobes
disable_kprobe(struct kprobe
*kp
)
1970 mutex_lock(&kprobe_mutex
);
1972 /* Disable this kprobe */
1973 if (__disable_kprobe(kp
) == NULL
)
1976 mutex_unlock(&kprobe_mutex
);
1979 EXPORT_SYMBOL_GPL(disable_kprobe
);
1981 /* Enable one kprobe */
1982 int __kprobes
enable_kprobe(struct kprobe
*kp
)
1987 mutex_lock(&kprobe_mutex
);
1989 /* Check whether specified probe is valid. */
1990 p
= __get_valid_kprobe(kp
);
1991 if (unlikely(p
== NULL
)) {
1996 if (kprobe_gone(kp
)) {
1997 /* This kprobe has gone, we couldn't enable it. */
2003 kp
->flags
&= ~KPROBE_FLAG_DISABLED
;
2005 if (!kprobes_all_disarmed
&& kprobe_disabled(p
)) {
2006 p
->flags
&= ~KPROBE_FLAG_DISABLED
;
2010 mutex_unlock(&kprobe_mutex
);
2013 EXPORT_SYMBOL_GPL(enable_kprobe
);
2015 void __kprobes
dump_kprobe(struct kprobe
*kp
)
2017 printk(KERN_WARNING
"Dumping kprobe:\n");
2018 printk(KERN_WARNING
"Name: %s\nAddress: %p\nOffset: %x\n",
2019 kp
->symbol_name
, kp
->addr
, kp
->offset
);
2022 /* Module notifier call back, checking kprobes on the module */
2023 static int __kprobes
kprobes_module_callback(struct notifier_block
*nb
,
2024 unsigned long val
, void *data
)
2026 struct module
*mod
= data
;
2027 struct hlist_head
*head
;
2030 int checkcore
= (val
== MODULE_STATE_GOING
);
2032 if (val
!= MODULE_STATE_GOING
&& val
!= MODULE_STATE_LIVE
)
2036 * When MODULE_STATE_GOING was notified, both of module .text and
2037 * .init.text sections would be freed. When MODULE_STATE_LIVE was
2038 * notified, only .init.text section would be freed. We need to
2039 * disable kprobes which have been inserted in the sections.
2041 mutex_lock(&kprobe_mutex
);
2042 for (i
= 0; i
< KPROBE_TABLE_SIZE
; i
++) {
2043 head
= &kprobe_table
[i
];
2044 hlist_for_each_entry_rcu(p
, head
, hlist
)
2045 if (within_module_init((unsigned long)p
->addr
, mod
) ||
2047 within_module_core((unsigned long)p
->addr
, mod
))) {
2049 * The vaddr this probe is installed will soon
2050 * be vfreed buy not synced to disk. Hence,
2051 * disarming the breakpoint isn't needed.
2056 mutex_unlock(&kprobe_mutex
);
2060 static struct notifier_block kprobe_module_nb
= {
2061 .notifier_call
= kprobes_module_callback
,
2065 static int __init
init_kprobes(void)
2068 unsigned long offset
= 0, size
= 0;
2069 char *modname
, namebuf
[128];
2070 const char *symbol_name
;
2072 struct kprobe_blackpoint
*kb
;
2074 /* FIXME allocate the probe table, currently defined statically */
2075 /* initialize all list heads */
2076 for (i
= 0; i
< KPROBE_TABLE_SIZE
; i
++) {
2077 INIT_HLIST_HEAD(&kprobe_table
[i
]);
2078 INIT_HLIST_HEAD(&kretprobe_inst_table
[i
]);
2079 raw_spin_lock_init(&(kretprobe_table_locks
[i
].lock
));
2083 * Lookup and populate the kprobe_blacklist.
2085 * Unlike the kretprobe blacklist, we'll need to determine
2086 * the range of addresses that belong to the said functions,
2087 * since a kprobe need not necessarily be at the beginning
2090 for (kb
= kprobe_blacklist
; kb
->name
!= NULL
; kb
++) {
2091 kprobe_lookup_name(kb
->name
, addr
);
2095 kb
->start_addr
= (unsigned long)addr
;
2096 symbol_name
= kallsyms_lookup(kb
->start_addr
,
2097 &size
, &offset
, &modname
, namebuf
);
2104 if (kretprobe_blacklist_size
) {
2105 /* lookup the function address from its name */
2106 for (i
= 0; kretprobe_blacklist
[i
].name
!= NULL
; i
++) {
2107 kprobe_lookup_name(kretprobe_blacklist
[i
].name
,
2108 kretprobe_blacklist
[i
].addr
);
2109 if (!kretprobe_blacklist
[i
].addr
)
2110 printk("kretprobe: lookup failed: %s\n",
2111 kretprobe_blacklist
[i
].name
);
2115 #if defined(CONFIG_OPTPROBES)
2116 #if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
2117 /* Init kprobe_optinsn_slots */
2118 kprobe_optinsn_slots
.insn_size
= MAX_OPTINSN_SIZE
;
2120 /* By default, kprobes can be optimized */
2121 kprobes_allow_optimization
= true;
2124 /* By default, kprobes are armed */
2125 kprobes_all_disarmed
= false;
2127 err
= arch_init_kprobes();
2129 err
= register_die_notifier(&kprobe_exceptions_nb
);
2131 err
= register_module_notifier(&kprobe_module_nb
);
2133 kprobes_initialized
= (err
== 0);
2140 #ifdef CONFIG_DEBUG_FS
2141 static void __kprobes
report_probe(struct seq_file
*pi
, struct kprobe
*p
,
2142 const char *sym
, int offset
, char *modname
, struct kprobe
*pp
)
2146 if (p
->pre_handler
== pre_handler_kretprobe
)
2148 else if (p
->pre_handler
== setjmp_pre_handler
)
2154 seq_printf(pi
, "%p %s %s+0x%x %s ",
2155 p
->addr
, kprobe_type
, sym
, offset
,
2156 (modname
? modname
: " "));
2158 seq_printf(pi
, "%p %s %p ",
2159 p
->addr
, kprobe_type
, p
->addr
);
2163 seq_printf(pi
, "%s%s%s%s\n",
2164 (kprobe_gone(p
) ? "[GONE]" : ""),
2165 ((kprobe_disabled(p
) && !kprobe_gone(p
)) ? "[DISABLED]" : ""),
2166 (kprobe_optimized(pp
) ? "[OPTIMIZED]" : ""),
2167 (kprobe_ftrace(pp
) ? "[FTRACE]" : ""));
2170 static void __kprobes
*kprobe_seq_start(struct seq_file
*f
, loff_t
*pos
)
2172 return (*pos
< KPROBE_TABLE_SIZE
) ? pos
: NULL
;
2175 static void __kprobes
*kprobe_seq_next(struct seq_file
*f
, void *v
, loff_t
*pos
)
2178 if (*pos
>= KPROBE_TABLE_SIZE
)
2183 static void __kprobes
kprobe_seq_stop(struct seq_file
*f
, void *v
)
2188 static int __kprobes
show_kprobe_addr(struct seq_file
*pi
, void *v
)
2190 struct hlist_head
*head
;
2191 struct kprobe
*p
, *kp
;
2192 const char *sym
= NULL
;
2193 unsigned int i
= *(loff_t
*) v
;
2194 unsigned long offset
= 0;
2195 char *modname
, namebuf
[128];
2197 head
= &kprobe_table
[i
];
2199 hlist_for_each_entry_rcu(p
, head
, hlist
) {
2200 sym
= kallsyms_lookup((unsigned long)p
->addr
, NULL
,
2201 &offset
, &modname
, namebuf
);
2202 if (kprobe_aggrprobe(p
)) {
2203 list_for_each_entry_rcu(kp
, &p
->list
, list
)
2204 report_probe(pi
, kp
, sym
, offset
, modname
, p
);
2206 report_probe(pi
, p
, sym
, offset
, modname
, NULL
);
2212 static const struct seq_operations kprobes_seq_ops
= {
2213 .start
= kprobe_seq_start
,
2214 .next
= kprobe_seq_next
,
2215 .stop
= kprobe_seq_stop
,
2216 .show
= show_kprobe_addr
2219 static int __kprobes
kprobes_open(struct inode
*inode
, struct file
*filp
)
2221 return seq_open(filp
, &kprobes_seq_ops
);
2224 static const struct file_operations debugfs_kprobes_operations
= {
2225 .open
= kprobes_open
,
2227 .llseek
= seq_lseek
,
2228 .release
= seq_release
,
2231 static void __kprobes
arm_all_kprobes(void)
2233 struct hlist_head
*head
;
2237 mutex_lock(&kprobe_mutex
);
2239 /* If kprobes are armed, just return */
2240 if (!kprobes_all_disarmed
)
2241 goto already_enabled
;
2243 /* Arming kprobes doesn't optimize kprobe itself */
2244 for (i
= 0; i
< KPROBE_TABLE_SIZE
; i
++) {
2245 head
= &kprobe_table
[i
];
2246 hlist_for_each_entry_rcu(p
, head
, hlist
)
2247 if (!kprobe_disabled(p
))
2251 kprobes_all_disarmed
= false;
2252 printk(KERN_INFO
"Kprobes globally enabled\n");
2255 mutex_unlock(&kprobe_mutex
);
2259 static void __kprobes
disarm_all_kprobes(void)
2261 struct hlist_head
*head
;
2265 mutex_lock(&kprobe_mutex
);
2267 /* If kprobes are already disarmed, just return */
2268 if (kprobes_all_disarmed
) {
2269 mutex_unlock(&kprobe_mutex
);
2273 kprobes_all_disarmed
= true;
2274 printk(KERN_INFO
"Kprobes globally disabled\n");
2276 for (i
= 0; i
< KPROBE_TABLE_SIZE
; i
++) {
2277 head
= &kprobe_table
[i
];
2278 hlist_for_each_entry_rcu(p
, head
, hlist
) {
2279 if (!arch_trampoline_kprobe(p
) && !kprobe_disabled(p
))
2280 disarm_kprobe(p
, false);
2283 mutex_unlock(&kprobe_mutex
);
2285 /* Wait for disarming all kprobes by optimizer */
2286 wait_for_kprobe_optimizer();
2290 * XXX: The debugfs bool file interface doesn't allow for callbacks
2291 * when the bool state is switched. We can reuse that facility when
2294 static ssize_t
read_enabled_file_bool(struct file
*file
,
2295 char __user
*user_buf
, size_t count
, loff_t
*ppos
)
2299 if (!kprobes_all_disarmed
)
2305 return simple_read_from_buffer(user_buf
, count
, ppos
, buf
, 2);
2308 static ssize_t
write_enabled_file_bool(struct file
*file
,
2309 const char __user
*user_buf
, size_t count
, loff_t
*ppos
)
2314 buf_size
= min(count
, (sizeof(buf
)-1));
2315 if (copy_from_user(buf
, user_buf
, buf_size
))
2318 buf
[buf_size
] = '\0';
2328 disarm_all_kprobes();
2337 static const struct file_operations fops_kp
= {
2338 .read
= read_enabled_file_bool
,
2339 .write
= write_enabled_file_bool
,
2340 .llseek
= default_llseek
,
2343 static int __kprobes
debugfs_kprobe_init(void)
2345 struct dentry
*dir
, *file
;
2346 unsigned int value
= 1;
2348 dir
= debugfs_create_dir("kprobes", NULL
);
2352 file
= debugfs_create_file("list", 0444, dir
, NULL
,
2353 &debugfs_kprobes_operations
);
2355 debugfs_remove(dir
);
2359 file
= debugfs_create_file("enabled", 0600, dir
,
2362 debugfs_remove(dir
);
2369 late_initcall(debugfs_kprobe_init
);
2370 #endif /* CONFIG_DEBUG_FS */
2372 module_init(init_kprobes
);
2374 /* defined in arch/.../kernel/kprobes.c */
2375 EXPORT_SYMBOL_GPL(jprobe_return
);