1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Kernel Probes (KProbes)
5 * Copyright (C) IBM Corporation, 2002, 2004
7 * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
8 * Probes initial implementation (includes suggestions from
10 * 2004-Aug Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with
11 * hlists and exceptions notifier as suggested by Andi Kleen.
12 * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
13 * interface to access function arguments.
14 * 2004-Sep Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
15 * exceptions notifier to be first on the priority list.
16 * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston
17 * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
18 * <prasanna@in.ibm.com> added function-return probes.
21 #define pr_fmt(fmt) "kprobes: " fmt
23 #include <linux/kprobes.h>
24 #include <linux/hash.h>
25 #include <linux/init.h>
26 #include <linux/slab.h>
27 #include <linux/stddef.h>
28 #include <linux/export.h>
29 #include <linux/moduleloader.h>
30 #include <linux/kallsyms.h>
31 #include <linux/freezer.h>
32 #include <linux/seq_file.h>
33 #include <linux/debugfs.h>
34 #include <linux/sysctl.h>
35 #include <linux/kdebug.h>
36 #include <linux/memory.h>
37 #include <linux/ftrace.h>
38 #include <linux/cpu.h>
39 #include <linux/jump_label.h>
40 #include <linux/static_call.h>
41 #include <linux/perf_event.h>
43 #include <asm/sections.h>
44 #include <asm/cacheflush.h>
45 #include <asm/errno.h>
46 #include <linux/uaccess.h>
48 #define KPROBE_HASH_BITS 6
49 #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
51 #if !defined(CONFIG_OPTPROBES) || !defined(CONFIG_SYSCTL)
52 #define kprobe_sysctls_init() do { } while (0)
55 static int kprobes_initialized
;
56 /* kprobe_table can be accessed by
57 * - Normal hlist traversal and RCU add/del under 'kprobe_mutex' is held.
59 * - RCU hlist traversal under disabling preempt (breakpoint handlers)
61 static struct hlist_head kprobe_table
[KPROBE_TABLE_SIZE
];
63 /* NOTE: change this value only with 'kprobe_mutex' held */
64 static bool kprobes_all_disarmed
;
66 /* This protects 'kprobe_table' and 'optimizing_list' */
67 static DEFINE_MUTEX(kprobe_mutex
);
68 static DEFINE_PER_CPU(struct kprobe
*, kprobe_instance
);
70 kprobe_opcode_t
* __weak
kprobe_lookup_name(const char *name
,
71 unsigned int __unused
)
73 return ((kprobe_opcode_t
*)(kallsyms_lookup_name(name
)));
77 * Blacklist -- list of 'struct kprobe_blacklist_entry' to store info where
78 * kprobes can not probe.
80 static LIST_HEAD(kprobe_blacklist
);
82 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
84 * 'kprobe::ainsn.insn' points to the copy of the instruction to be
85 * single-stepped. x86_64, POWER4 and above have no-exec support and
86 * stepping on the instruction on a vmalloced/kmalloced/data page
87 * is a recipe for disaster
89 struct kprobe_insn_page
{
90 struct list_head list
;
91 kprobe_opcode_t
*insns
; /* Page of instruction slots */
92 struct kprobe_insn_cache
*cache
;
98 #define KPROBE_INSN_PAGE_SIZE(slots) \
99 (offsetof(struct kprobe_insn_page, slot_used) + \
100 (sizeof(char) * (slots)))
102 static int slots_per_page(struct kprobe_insn_cache
*c
)
104 return PAGE_SIZE
/(c
->insn_size
* sizeof(kprobe_opcode_t
));
107 enum kprobe_slot_state
{
113 void __weak
*alloc_insn_page(void)
116 * Use module_alloc() so this page is within +/- 2GB of where the
117 * kernel image and loaded module images reside. This is required
118 * for most of the architectures.
119 * (e.g. x86-64 needs this to handle the %rip-relative fixups.)
121 return module_alloc(PAGE_SIZE
);
124 static void free_insn_page(void *page
)
126 module_memfree(page
);
129 struct kprobe_insn_cache kprobe_insn_slots
= {
130 .mutex
= __MUTEX_INITIALIZER(kprobe_insn_slots
.mutex
),
131 .alloc
= alloc_insn_page
,
132 .free
= free_insn_page
,
133 .sym
= KPROBE_INSN_PAGE_SYM
,
134 .pages
= LIST_HEAD_INIT(kprobe_insn_slots
.pages
),
135 .insn_size
= MAX_INSN_SIZE
,
138 static int collect_garbage_slots(struct kprobe_insn_cache
*c
);
141 * __get_insn_slot() - Find a slot on an executable page for an instruction.
142 * We allocate an executable page if there's no room on existing ones.
144 kprobe_opcode_t
*__get_insn_slot(struct kprobe_insn_cache
*c
)
146 struct kprobe_insn_page
*kip
;
147 kprobe_opcode_t
*slot
= NULL
;
149 /* Since the slot array is not protected by rcu, we need a mutex */
150 mutex_lock(&c
->mutex
);
153 list_for_each_entry_rcu(kip
, &c
->pages
, list
) {
154 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
);
166 /* kip->nused is broken. Fix it. */
167 kip
->nused
= slots_per_page(c
);
173 /* If there are any garbage slots, collect it and try again. */
174 if (c
->nr_garbage
&& collect_garbage_slots(c
) == 0)
177 /* All out of space. Need to allocate a new page. */
178 kip
= kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c
)), GFP_KERNEL
);
182 kip
->insns
= c
->alloc();
187 INIT_LIST_HEAD(&kip
->list
);
188 memset(kip
->slot_used
, SLOT_CLEAN
, slots_per_page(c
));
189 kip
->slot_used
[0] = SLOT_USED
;
193 list_add_rcu(&kip
->list
, &c
->pages
);
196 /* Record the perf ksymbol register event after adding the page */
197 perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL
, (unsigned long)kip
->insns
,
198 PAGE_SIZE
, false, c
->sym
);
200 mutex_unlock(&c
->mutex
);
204 /* Return true if all garbages are collected, otherwise false. */
205 static bool collect_one_slot(struct kprobe_insn_page
*kip
, int idx
)
207 kip
->slot_used
[idx
] = SLOT_CLEAN
;
209 if (kip
->nused
== 0) {
211 * Page is no longer in use. Free it unless
212 * it's the last one. We keep the last one
213 * so as not to have to set it up again the
214 * next time somebody inserts a probe.
216 if (!list_is_singular(&kip
->list
)) {
218 * Record perf ksymbol unregister event before removing
221 perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL
,
222 (unsigned long)kip
->insns
, PAGE_SIZE
, true,
224 list_del_rcu(&kip
->list
);
226 kip
->cache
->free(kip
->insns
);
234 static int collect_garbage_slots(struct kprobe_insn_cache
*c
)
236 struct kprobe_insn_page
*kip
, *next
;
238 /* Ensure no-one is interrupted on the garbages */
241 list_for_each_entry_safe(kip
, next
, &c
->pages
, list
) {
244 if (kip
->ngarbage
== 0)
246 kip
->ngarbage
= 0; /* we will collect all garbages */
247 for (i
= 0; i
< slots_per_page(c
); i
++) {
248 if (kip
->slot_used
[i
] == SLOT_DIRTY
&& collect_one_slot(kip
, i
))
256 void __free_insn_slot(struct kprobe_insn_cache
*c
,
257 kprobe_opcode_t
*slot
, int dirty
)
259 struct kprobe_insn_page
*kip
;
262 mutex_lock(&c
->mutex
);
264 list_for_each_entry_rcu(kip
, &c
->pages
, list
) {
265 idx
= ((long)slot
- (long)kip
->insns
) /
266 (c
->insn_size
* sizeof(kprobe_opcode_t
));
267 if (idx
>= 0 && idx
< slots_per_page(c
))
270 /* Could not find this slot. */
275 /* Mark and sweep: this may sleep */
277 /* Check double free */
278 WARN_ON(kip
->slot_used
[idx
] != SLOT_USED
);
280 kip
->slot_used
[idx
] = SLOT_DIRTY
;
282 if (++c
->nr_garbage
> slots_per_page(c
))
283 collect_garbage_slots(c
);
285 collect_one_slot(kip
, idx
);
288 mutex_unlock(&c
->mutex
);
292 * Check given address is on the page of kprobe instruction slots.
293 * This will be used for checking whether the address on a stack
294 * is on a text area or not.
296 bool __is_insn_slot_addr(struct kprobe_insn_cache
*c
, unsigned long addr
)
298 struct kprobe_insn_page
*kip
;
302 list_for_each_entry_rcu(kip
, &c
->pages
, list
) {
303 if (addr
>= (unsigned long)kip
->insns
&&
304 addr
< (unsigned long)kip
->insns
+ PAGE_SIZE
) {
314 int kprobe_cache_get_kallsym(struct kprobe_insn_cache
*c
, unsigned int *symnum
,
315 unsigned long *value
, char *type
, char *sym
)
317 struct kprobe_insn_page
*kip
;
321 list_for_each_entry_rcu(kip
, &c
->pages
, list
) {
324 strscpy(sym
, c
->sym
, KSYM_NAME_LEN
);
326 *value
= (unsigned long)kip
->insns
;
335 #ifdef CONFIG_OPTPROBES
336 void __weak
*alloc_optinsn_page(void)
338 return alloc_insn_page();
341 void __weak
free_optinsn_page(void *page
)
343 free_insn_page(page
);
346 /* For optimized_kprobe buffer */
347 struct kprobe_insn_cache kprobe_optinsn_slots
= {
348 .mutex
= __MUTEX_INITIALIZER(kprobe_optinsn_slots
.mutex
),
349 .alloc
= alloc_optinsn_page
,
350 .free
= free_optinsn_page
,
351 .sym
= KPROBE_OPTINSN_PAGE_SYM
,
352 .pages
= LIST_HEAD_INIT(kprobe_optinsn_slots
.pages
),
353 /* .insn_size is initialized later */
359 /* We have preemption disabled.. so it is safe to use __ versions */
360 static inline void set_kprobe_instance(struct kprobe
*kp
)
362 __this_cpu_write(kprobe_instance
, kp
);
365 static inline void reset_kprobe_instance(void)
367 __this_cpu_write(kprobe_instance
, NULL
);
371 * This routine is called either:
372 * - under the 'kprobe_mutex' - during kprobe_[un]register().
374 * - with preemption disabled - from architecture specific code.
376 struct kprobe
*get_kprobe(void *addr
)
378 struct hlist_head
*head
;
381 head
= &kprobe_table
[hash_ptr(addr
, KPROBE_HASH_BITS
)];
382 hlist_for_each_entry_rcu(p
, head
, hlist
,
383 lockdep_is_held(&kprobe_mutex
)) {
390 NOKPROBE_SYMBOL(get_kprobe
);
392 static int aggr_pre_handler(struct kprobe
*p
, struct pt_regs
*regs
);
394 /* Return true if 'p' is an aggregator */
395 static inline bool kprobe_aggrprobe(struct kprobe
*p
)
397 return p
->pre_handler
== aggr_pre_handler
;
400 /* Return true if 'p' is unused */
401 static inline bool kprobe_unused(struct kprobe
*p
)
403 return kprobe_aggrprobe(p
) && kprobe_disabled(p
) &&
404 list_empty(&p
->list
);
407 /* Keep all fields in the kprobe consistent. */
408 static inline void copy_kprobe(struct kprobe
*ap
, struct kprobe
*p
)
410 memcpy(&p
->opcode
, &ap
->opcode
, sizeof(kprobe_opcode_t
));
411 memcpy(&p
->ainsn
, &ap
->ainsn
, sizeof(struct arch_specific_insn
));
414 #ifdef CONFIG_OPTPROBES
415 /* NOTE: This is protected by 'kprobe_mutex'. */
416 static bool kprobes_allow_optimization
;
419 * Call all 'kprobe::pre_handler' on the list, but ignores its return value.
420 * This must be called from arch-dep optimized caller.
422 void opt_pre_handler(struct kprobe
*p
, struct pt_regs
*regs
)
426 list_for_each_entry_rcu(kp
, &p
->list
, list
) {
427 if (kp
->pre_handler
&& likely(!kprobe_disabled(kp
))) {
428 set_kprobe_instance(kp
);
429 kp
->pre_handler(kp
, regs
);
431 reset_kprobe_instance();
434 NOKPROBE_SYMBOL(opt_pre_handler
);
436 /* Free optimized instructions and optimized_kprobe */
437 static void free_aggr_kprobe(struct kprobe
*p
)
439 struct optimized_kprobe
*op
;
441 op
= container_of(p
, struct optimized_kprobe
, kp
);
442 arch_remove_optimized_kprobe(op
);
443 arch_remove_kprobe(p
);
447 /* Return true if the kprobe is ready for optimization. */
448 static inline int kprobe_optready(struct kprobe
*p
)
450 struct optimized_kprobe
*op
;
452 if (kprobe_aggrprobe(p
)) {
453 op
= container_of(p
, struct optimized_kprobe
, kp
);
454 return arch_prepared_optinsn(&op
->optinsn
);
460 /* Return true if the kprobe is disarmed. Note: p must be on hash list */
461 bool kprobe_disarmed(struct kprobe
*p
)
463 struct optimized_kprobe
*op
;
465 /* If kprobe is not aggr/opt probe, just return kprobe is disabled */
466 if (!kprobe_aggrprobe(p
))
467 return kprobe_disabled(p
);
469 op
= container_of(p
, struct optimized_kprobe
, kp
);
471 return kprobe_disabled(p
) && list_empty(&op
->list
);
474 /* Return true if the probe is queued on (un)optimizing lists */
475 static bool kprobe_queued(struct kprobe
*p
)
477 struct optimized_kprobe
*op
;
479 if (kprobe_aggrprobe(p
)) {
480 op
= container_of(p
, struct optimized_kprobe
, kp
);
481 if (!list_empty(&op
->list
))
488 * Return an optimized kprobe whose optimizing code replaces
489 * instructions including 'addr' (exclude breakpoint).
491 static struct kprobe
*get_optimized_kprobe(kprobe_opcode_t
*addr
)
494 struct kprobe
*p
= NULL
;
495 struct optimized_kprobe
*op
;
497 /* Don't check i == 0, since that is a breakpoint case. */
498 for (i
= 1; !p
&& i
< MAX_OPTIMIZED_LENGTH
/ sizeof(kprobe_opcode_t
); i
++)
499 p
= get_kprobe(addr
- i
);
501 if (p
&& kprobe_optready(p
)) {
502 op
= container_of(p
, struct optimized_kprobe
, kp
);
503 if (arch_within_optimized_kprobe(op
, addr
))
510 /* Optimization staging list, protected by 'kprobe_mutex' */
511 static LIST_HEAD(optimizing_list
);
512 static LIST_HEAD(unoptimizing_list
);
513 static LIST_HEAD(freeing_list
);
515 static void kprobe_optimizer(struct work_struct
*work
);
516 static DECLARE_DELAYED_WORK(optimizing_work
, kprobe_optimizer
);
517 #define OPTIMIZE_DELAY 5
520 * Optimize (replace a breakpoint with a jump) kprobes listed on
523 static void do_optimize_kprobes(void)
525 lockdep_assert_held(&text_mutex
);
527 * The optimization/unoptimization refers 'online_cpus' via
528 * stop_machine() and cpu-hotplug modifies the 'online_cpus'.
529 * And same time, 'text_mutex' will be held in cpu-hotplug and here.
530 * This combination can cause a deadlock (cpu-hotplug tries to lock
531 * 'text_mutex' but stop_machine() can not be done because
532 * the 'online_cpus' has been changed)
533 * To avoid this deadlock, caller must have locked cpu-hotplug
534 * for preventing cpu-hotplug outside of 'text_mutex' locking.
536 lockdep_assert_cpus_held();
538 /* Optimization never be done when disarmed */
539 if (kprobes_all_disarmed
|| !kprobes_allow_optimization
||
540 list_empty(&optimizing_list
))
543 arch_optimize_kprobes(&optimizing_list
);
547 * Unoptimize (replace a jump with a breakpoint and remove the breakpoint
548 * if need) kprobes listed on 'unoptimizing_list'.
550 static void do_unoptimize_kprobes(void)
552 struct optimized_kprobe
*op
, *tmp
;
554 lockdep_assert_held(&text_mutex
);
555 /* See comment in do_optimize_kprobes() */
556 lockdep_assert_cpus_held();
558 if (!list_empty(&unoptimizing_list
))
559 arch_unoptimize_kprobes(&unoptimizing_list
, &freeing_list
);
561 /* Loop on 'freeing_list' for disarming and removing from kprobe hash list */
562 list_for_each_entry_safe(op
, tmp
, &freeing_list
, list
) {
563 /* Switching from detour code to origin */
564 op
->kp
.flags
&= ~KPROBE_FLAG_OPTIMIZED
;
565 /* Disarm probes if marked disabled and not gone */
566 if (kprobe_disabled(&op
->kp
) && !kprobe_gone(&op
->kp
))
567 arch_disarm_kprobe(&op
->kp
);
568 if (kprobe_unused(&op
->kp
)) {
570 * Remove unused probes from hash list. After waiting
571 * for synchronization, these probes are reclaimed.
572 * (reclaiming is done by do_free_cleaned_kprobes().)
574 hlist_del_rcu(&op
->kp
.hlist
);
576 list_del_init(&op
->list
);
580 /* Reclaim all kprobes on the 'freeing_list' */
581 static void do_free_cleaned_kprobes(void)
583 struct optimized_kprobe
*op
, *tmp
;
585 list_for_each_entry_safe(op
, tmp
, &freeing_list
, list
) {
586 list_del_init(&op
->list
);
587 if (WARN_ON_ONCE(!kprobe_unused(&op
->kp
))) {
589 * This must not happen, but if there is a kprobe
590 * still in use, keep it on kprobes hash list.
594 free_aggr_kprobe(&op
->kp
);
598 /* Start optimizer after OPTIMIZE_DELAY passed */
599 static void kick_kprobe_optimizer(void)
601 schedule_delayed_work(&optimizing_work
, OPTIMIZE_DELAY
);
604 /* Kprobe jump optimizer */
605 static void kprobe_optimizer(struct work_struct
*work
)
607 mutex_lock(&kprobe_mutex
);
609 mutex_lock(&text_mutex
);
612 * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
613 * kprobes before waiting for quiesence period.
615 do_unoptimize_kprobes();
618 * Step 2: Wait for quiesence period to ensure all potentially
619 * preempted tasks to have normally scheduled. Because optprobe
620 * may modify multiple instructions, there is a chance that Nth
621 * instruction is preempted. In that case, such tasks can return
622 * to 2nd-Nth byte of jump instruction. This wait is for avoiding it.
623 * Note that on non-preemptive kernel, this is transparently converted
624 * to synchronoze_sched() to wait for all interrupts to have completed.
626 synchronize_rcu_tasks();
628 /* Step 3: Optimize kprobes after quiesence period */
629 do_optimize_kprobes();
631 /* Step 4: Free cleaned kprobes after quiesence period */
632 do_free_cleaned_kprobes();
634 mutex_unlock(&text_mutex
);
637 /* Step 5: Kick optimizer again if needed */
638 if (!list_empty(&optimizing_list
) || !list_empty(&unoptimizing_list
))
639 kick_kprobe_optimizer();
641 mutex_unlock(&kprobe_mutex
);
644 /* Wait for completing optimization and unoptimization */
645 void wait_for_kprobe_optimizer(void)
647 mutex_lock(&kprobe_mutex
);
649 while (!list_empty(&optimizing_list
) || !list_empty(&unoptimizing_list
)) {
650 mutex_unlock(&kprobe_mutex
);
652 /* This will also make 'optimizing_work' execute immmediately */
653 flush_delayed_work(&optimizing_work
);
654 /* 'optimizing_work' might not have been queued yet, relax */
657 mutex_lock(&kprobe_mutex
);
660 mutex_unlock(&kprobe_mutex
);
663 bool optprobe_queued_unopt(struct optimized_kprobe
*op
)
665 struct optimized_kprobe
*_op
;
667 list_for_each_entry(_op
, &unoptimizing_list
, list
) {
675 /* Optimize kprobe if p is ready to be optimized */
676 static void optimize_kprobe(struct kprobe
*p
)
678 struct optimized_kprobe
*op
;
680 /* Check if the kprobe is disabled or not ready for optimization. */
681 if (!kprobe_optready(p
) || !kprobes_allow_optimization
||
682 (kprobe_disabled(p
) || kprobes_all_disarmed
))
685 /* kprobes with 'post_handler' can not be optimized */
689 op
= container_of(p
, struct optimized_kprobe
, kp
);
691 /* Check there is no other kprobes at the optimized instructions */
692 if (arch_check_optimized_kprobe(op
) < 0)
695 /* Check if it is already optimized. */
696 if (op
->kp
.flags
& KPROBE_FLAG_OPTIMIZED
) {
697 if (optprobe_queued_unopt(op
)) {
698 /* This is under unoptimizing. Just dequeue the probe */
699 list_del_init(&op
->list
);
703 op
->kp
.flags
|= KPROBE_FLAG_OPTIMIZED
;
706 * On the 'unoptimizing_list' and 'optimizing_list',
707 * 'op' must have OPTIMIZED flag
709 if (WARN_ON_ONCE(!list_empty(&op
->list
)))
712 list_add(&op
->list
, &optimizing_list
);
713 kick_kprobe_optimizer();
716 /* Short cut to direct unoptimizing */
717 static void force_unoptimize_kprobe(struct optimized_kprobe
*op
)
719 lockdep_assert_cpus_held();
720 arch_unoptimize_kprobe(op
);
721 op
->kp
.flags
&= ~KPROBE_FLAG_OPTIMIZED
;
724 /* Unoptimize a kprobe if p is optimized */
725 static void unoptimize_kprobe(struct kprobe
*p
, bool force
)
727 struct optimized_kprobe
*op
;
729 if (!kprobe_aggrprobe(p
) || kprobe_disarmed(p
))
730 return; /* This is not an optprobe nor optimized */
732 op
= container_of(p
, struct optimized_kprobe
, kp
);
733 if (!kprobe_optimized(p
))
736 if (!list_empty(&op
->list
)) {
737 if (optprobe_queued_unopt(op
)) {
738 /* Queued in unoptimizing queue */
741 * Forcibly unoptimize the kprobe here, and queue it
742 * in the freeing list for release afterwards.
744 force_unoptimize_kprobe(op
);
745 list_move(&op
->list
, &freeing_list
);
748 /* Dequeue from the optimizing queue */
749 list_del_init(&op
->list
);
750 op
->kp
.flags
&= ~KPROBE_FLAG_OPTIMIZED
;
755 /* Optimized kprobe case */
757 /* Forcibly update the code: this is a special case */
758 force_unoptimize_kprobe(op
);
760 list_add(&op
->list
, &unoptimizing_list
);
761 kick_kprobe_optimizer();
765 /* Cancel unoptimizing for reusing */
766 static int reuse_unused_kprobe(struct kprobe
*ap
)
768 struct optimized_kprobe
*op
;
771 * Unused kprobe MUST be on the way of delayed unoptimizing (means
772 * there is still a relative jump) and disabled.
774 op
= container_of(ap
, struct optimized_kprobe
, kp
);
775 WARN_ON_ONCE(list_empty(&op
->list
));
776 /* Enable the probe again */
777 ap
->flags
&= ~KPROBE_FLAG_DISABLED
;
778 /* Optimize it again. (remove from 'op->list') */
779 if (!kprobe_optready(ap
))
786 /* Remove optimized instructions */
787 static void kill_optimized_kprobe(struct kprobe
*p
)
789 struct optimized_kprobe
*op
;
791 op
= container_of(p
, struct optimized_kprobe
, kp
);
792 if (!list_empty(&op
->list
))
793 /* Dequeue from the (un)optimization queue */
794 list_del_init(&op
->list
);
795 op
->kp
.flags
&= ~KPROBE_FLAG_OPTIMIZED
;
797 if (kprobe_unused(p
)) {
799 * Unused kprobe is on unoptimizing or freeing list. We move it
800 * to freeing_list and let the kprobe_optimizer() remove it from
801 * the kprobe hash list and free it.
803 if (optprobe_queued_unopt(op
))
804 list_move(&op
->list
, &freeing_list
);
807 /* Don't touch the code, because it is already freed. */
808 arch_remove_optimized_kprobe(op
);
812 void __prepare_optimized_kprobe(struct optimized_kprobe
*op
, struct kprobe
*p
)
814 if (!kprobe_ftrace(p
))
815 arch_prepare_optimized_kprobe(op
, p
);
818 /* Try to prepare optimized instructions */
819 static void prepare_optimized_kprobe(struct kprobe
*p
)
821 struct optimized_kprobe
*op
;
823 op
= container_of(p
, struct optimized_kprobe
, kp
);
824 __prepare_optimized_kprobe(op
, p
);
827 /* Allocate new optimized_kprobe and try to prepare optimized instructions. */
828 static struct kprobe
*alloc_aggr_kprobe(struct kprobe
*p
)
830 struct optimized_kprobe
*op
;
832 op
= kzalloc(sizeof(struct optimized_kprobe
), GFP_KERNEL
);
836 INIT_LIST_HEAD(&op
->list
);
837 op
->kp
.addr
= p
->addr
;
838 __prepare_optimized_kprobe(op
, p
);
843 static void init_aggr_kprobe(struct kprobe
*ap
, struct kprobe
*p
);
846 * Prepare an optimized_kprobe and optimize it.
847 * NOTE: 'p' must be a normal registered kprobe.
849 static void try_to_optimize_kprobe(struct kprobe
*p
)
852 struct optimized_kprobe
*op
;
854 /* Impossible to optimize ftrace-based kprobe. */
855 if (kprobe_ftrace(p
))
858 /* For preparing optimization, jump_label_text_reserved() is called. */
861 mutex_lock(&text_mutex
);
863 ap
= alloc_aggr_kprobe(p
);
867 op
= container_of(ap
, struct optimized_kprobe
, kp
);
868 if (!arch_prepared_optinsn(&op
->optinsn
)) {
869 /* If failed to setup optimizing, fallback to kprobe. */
870 arch_remove_optimized_kprobe(op
);
875 init_aggr_kprobe(ap
, p
);
876 optimize_kprobe(ap
); /* This just kicks optimizer thread. */
879 mutex_unlock(&text_mutex
);
884 static void optimize_all_kprobes(void)
886 struct hlist_head
*head
;
890 mutex_lock(&kprobe_mutex
);
891 /* If optimization is already allowed, just return. */
892 if (kprobes_allow_optimization
)
896 kprobes_allow_optimization
= true;
897 for (i
= 0; i
< KPROBE_TABLE_SIZE
; i
++) {
898 head
= &kprobe_table
[i
];
899 hlist_for_each_entry(p
, head
, hlist
)
900 if (!kprobe_disabled(p
))
904 pr_info("kprobe jump-optimization is enabled. All kprobes are optimized if possible.\n");
906 mutex_unlock(&kprobe_mutex
);
910 static void unoptimize_all_kprobes(void)
912 struct hlist_head
*head
;
916 mutex_lock(&kprobe_mutex
);
917 /* If optimization is already prohibited, just return. */
918 if (!kprobes_allow_optimization
) {
919 mutex_unlock(&kprobe_mutex
);
924 kprobes_allow_optimization
= false;
925 for (i
= 0; i
< KPROBE_TABLE_SIZE
; i
++) {
926 head
= &kprobe_table
[i
];
927 hlist_for_each_entry(p
, head
, hlist
) {
928 if (!kprobe_disabled(p
))
929 unoptimize_kprobe(p
, false);
933 mutex_unlock(&kprobe_mutex
);
935 /* Wait for unoptimizing completion. */
936 wait_for_kprobe_optimizer();
937 pr_info("kprobe jump-optimization is disabled. All kprobes are based on software breakpoint.\n");
940 static DEFINE_MUTEX(kprobe_sysctl_mutex
);
941 static int sysctl_kprobes_optimization
;
942 static int proc_kprobes_optimization_handler(struct ctl_table
*table
,
943 int write
, void *buffer
,
944 size_t *length
, loff_t
*ppos
)
948 mutex_lock(&kprobe_sysctl_mutex
);
949 sysctl_kprobes_optimization
= kprobes_allow_optimization
? 1 : 0;
950 ret
= proc_dointvec_minmax(table
, write
, buffer
, length
, ppos
);
952 if (sysctl_kprobes_optimization
)
953 optimize_all_kprobes();
955 unoptimize_all_kprobes();
956 mutex_unlock(&kprobe_sysctl_mutex
);
961 static struct ctl_table kprobe_sysctls
[] = {
963 .procname
= "kprobes-optimization",
964 .data
= &sysctl_kprobes_optimization
,
965 .maxlen
= sizeof(int),
967 .proc_handler
= proc_kprobes_optimization_handler
,
968 .extra1
= SYSCTL_ZERO
,
969 .extra2
= SYSCTL_ONE
,
974 static void __init
kprobe_sysctls_init(void)
976 register_sysctl_init("debug", kprobe_sysctls
);
978 #endif /* CONFIG_SYSCTL */
980 /* Put a breakpoint for a probe. */
981 static void __arm_kprobe(struct kprobe
*p
)
985 lockdep_assert_held(&text_mutex
);
987 /* Find the overlapping optimized kprobes. */
988 _p
= get_optimized_kprobe(p
->addr
);
990 /* Fallback to unoptimized kprobe */
991 unoptimize_kprobe(_p
, true);
994 optimize_kprobe(p
); /* Try to optimize (add kprobe to a list) */
997 /* Remove the breakpoint of a probe. */
998 static void __disarm_kprobe(struct kprobe
*p
, bool reopt
)
1002 lockdep_assert_held(&text_mutex
);
1004 /* Try to unoptimize */
1005 unoptimize_kprobe(p
, kprobes_all_disarmed
);
1007 if (!kprobe_queued(p
)) {
1008 arch_disarm_kprobe(p
);
1009 /* If another kprobe was blocked, re-optimize it. */
1010 _p
= get_optimized_kprobe(p
->addr
);
1011 if (unlikely(_p
) && reopt
)
1012 optimize_kprobe(_p
);
1015 * TODO: Since unoptimization and real disarming will be done by
1016 * the worker thread, we can not check whether another probe are
1017 * unoptimized because of this probe here. It should be re-optimized
1018 * by the worker thread.
1022 #else /* !CONFIG_OPTPROBES */
1024 #define optimize_kprobe(p) do {} while (0)
1025 #define unoptimize_kprobe(p, f) do {} while (0)
1026 #define kill_optimized_kprobe(p) do {} while (0)
1027 #define prepare_optimized_kprobe(p) do {} while (0)
1028 #define try_to_optimize_kprobe(p) do {} while (0)
1029 #define __arm_kprobe(p) arch_arm_kprobe(p)
1030 #define __disarm_kprobe(p, o) arch_disarm_kprobe(p)
1031 #define kprobe_disarmed(p) kprobe_disabled(p)
1032 #define wait_for_kprobe_optimizer() do {} while (0)
1034 static int reuse_unused_kprobe(struct kprobe
*ap
)
1037 * If the optimized kprobe is NOT supported, the aggr kprobe is
1038 * released at the same time that the last aggregated kprobe is
1040 * Thus there should be no chance to reuse unused kprobe.
1046 static void free_aggr_kprobe(struct kprobe
*p
)
1048 arch_remove_kprobe(p
);
1052 static struct kprobe
*alloc_aggr_kprobe(struct kprobe
*p
)
1054 return kzalloc(sizeof(struct kprobe
), GFP_KERNEL
);
1056 #endif /* CONFIG_OPTPROBES */
1058 #ifdef CONFIG_KPROBES_ON_FTRACE
1059 static struct ftrace_ops kprobe_ftrace_ops __read_mostly
= {
1060 .func
= kprobe_ftrace_handler
,
1061 .flags
= FTRACE_OPS_FL_SAVE_REGS
,
1064 static struct ftrace_ops kprobe_ipmodify_ops __read_mostly
= {
1065 .func
= kprobe_ftrace_handler
,
1066 .flags
= FTRACE_OPS_FL_SAVE_REGS
| FTRACE_OPS_FL_IPMODIFY
,
1069 static int kprobe_ipmodify_enabled
;
1070 static int kprobe_ftrace_enabled
;
1072 static int __arm_kprobe_ftrace(struct kprobe
*p
, struct ftrace_ops
*ops
,
1077 lockdep_assert_held(&kprobe_mutex
);
1079 ret
= ftrace_set_filter_ip(ops
, (unsigned long)p
->addr
, 0, 0);
1080 if (WARN_ONCE(ret
< 0, "Failed to arm kprobe-ftrace at %pS (error %d)\n", p
->addr
, ret
))
1084 ret
= register_ftrace_function(ops
);
1085 if (WARN(ret
< 0, "Failed to register kprobe-ftrace (error %d)\n", ret
))
1094 * At this point, sinec ops is not registered, we should be sefe from
1095 * registering empty filter.
1097 ftrace_set_filter_ip(ops
, (unsigned long)p
->addr
, 1, 0);
1101 static int arm_kprobe_ftrace(struct kprobe
*p
)
1103 bool ipmodify
= (p
->post_handler
!= NULL
);
1105 return __arm_kprobe_ftrace(p
,
1106 ipmodify
? &kprobe_ipmodify_ops
: &kprobe_ftrace_ops
,
1107 ipmodify
? &kprobe_ipmodify_enabled
: &kprobe_ftrace_enabled
);
1110 static int __disarm_kprobe_ftrace(struct kprobe
*p
, struct ftrace_ops
*ops
,
1115 lockdep_assert_held(&kprobe_mutex
);
1118 ret
= unregister_ftrace_function(ops
);
1119 if (WARN(ret
< 0, "Failed to unregister kprobe-ftrace (error %d)\n", ret
))
1125 ret
= ftrace_set_filter_ip(ops
, (unsigned long)p
->addr
, 1, 0);
1126 WARN_ONCE(ret
< 0, "Failed to disarm kprobe-ftrace at %pS (error %d)\n",
1131 static int disarm_kprobe_ftrace(struct kprobe
*p
)
1133 bool ipmodify
= (p
->post_handler
!= NULL
);
1135 return __disarm_kprobe_ftrace(p
,
1136 ipmodify
? &kprobe_ipmodify_ops
: &kprobe_ftrace_ops
,
1137 ipmodify
? &kprobe_ipmodify_enabled
: &kprobe_ftrace_enabled
);
1139 #else /* !CONFIG_KPROBES_ON_FTRACE */
1140 static inline int arm_kprobe_ftrace(struct kprobe
*p
)
1145 static inline int disarm_kprobe_ftrace(struct kprobe
*p
)
1151 static int prepare_kprobe(struct kprobe
*p
)
1153 /* Must ensure p->addr is really on ftrace */
1154 if (kprobe_ftrace(p
))
1155 return arch_prepare_kprobe_ftrace(p
);
1157 return arch_prepare_kprobe(p
);
1160 static int arm_kprobe(struct kprobe
*kp
)
1162 if (unlikely(kprobe_ftrace(kp
)))
1163 return arm_kprobe_ftrace(kp
);
1166 mutex_lock(&text_mutex
);
1168 mutex_unlock(&text_mutex
);
1174 static int disarm_kprobe(struct kprobe
*kp
, bool reopt
)
1176 if (unlikely(kprobe_ftrace(kp
)))
1177 return disarm_kprobe_ftrace(kp
);
1180 mutex_lock(&text_mutex
);
1181 __disarm_kprobe(kp
, reopt
);
1182 mutex_unlock(&text_mutex
);
1189 * Aggregate handlers for multiple kprobes support - these handlers
1190 * take care of invoking the individual kprobe handlers on p->list
1192 static int aggr_pre_handler(struct kprobe
*p
, struct pt_regs
*regs
)
1196 list_for_each_entry_rcu(kp
, &p
->list
, list
) {
1197 if (kp
->pre_handler
&& likely(!kprobe_disabled(kp
))) {
1198 set_kprobe_instance(kp
);
1199 if (kp
->pre_handler(kp
, regs
))
1202 reset_kprobe_instance();
1206 NOKPROBE_SYMBOL(aggr_pre_handler
);
1208 static void aggr_post_handler(struct kprobe
*p
, struct pt_regs
*regs
,
1209 unsigned long flags
)
1213 list_for_each_entry_rcu(kp
, &p
->list
, list
) {
1214 if (kp
->post_handler
&& likely(!kprobe_disabled(kp
))) {
1215 set_kprobe_instance(kp
);
1216 kp
->post_handler(kp
, regs
, flags
);
1217 reset_kprobe_instance();
1221 NOKPROBE_SYMBOL(aggr_post_handler
);
1223 /* Walks the list and increments 'nmissed' if 'p' has child probes. */
1224 void kprobes_inc_nmissed_count(struct kprobe
*p
)
1228 if (!kprobe_aggrprobe(p
)) {
1231 list_for_each_entry_rcu(kp
, &p
->list
, list
)
1235 NOKPROBE_SYMBOL(kprobes_inc_nmissed_count
);
1237 static struct kprobe kprobe_busy
= {
1238 .addr
= (void *) get_kprobe
,
1241 void kprobe_busy_begin(void)
1243 struct kprobe_ctlblk
*kcb
;
1246 __this_cpu_write(current_kprobe
, &kprobe_busy
);
1247 kcb
= get_kprobe_ctlblk();
1248 kcb
->kprobe_status
= KPROBE_HIT_ACTIVE
;
1251 void kprobe_busy_end(void)
1253 __this_cpu_write(current_kprobe
, NULL
);
1257 /* Add the new probe to 'ap->list'. */
1258 static int add_new_kprobe(struct kprobe
*ap
, struct kprobe
*p
)
1260 if (p
->post_handler
)
1261 unoptimize_kprobe(ap
, true); /* Fall back to normal kprobe */
1263 list_add_rcu(&p
->list
, &ap
->list
);
1264 if (p
->post_handler
&& !ap
->post_handler
)
1265 ap
->post_handler
= aggr_post_handler
;
1271 * Fill in the required fields of the aggregator kprobe. Replace the
1272 * earlier kprobe in the hlist with the aggregator kprobe.
1274 static void init_aggr_kprobe(struct kprobe
*ap
, struct kprobe
*p
)
1276 /* Copy the insn slot of 'p' to 'ap'. */
1278 flush_insn_slot(ap
);
1280 ap
->flags
= p
->flags
& ~KPROBE_FLAG_OPTIMIZED
;
1281 ap
->pre_handler
= aggr_pre_handler
;
1282 /* We don't care the kprobe which has gone. */
1283 if (p
->post_handler
&& !kprobe_gone(p
))
1284 ap
->post_handler
= aggr_post_handler
;
1286 INIT_LIST_HEAD(&ap
->list
);
1287 INIT_HLIST_NODE(&ap
->hlist
);
1289 list_add_rcu(&p
->list
, &ap
->list
);
1290 hlist_replace_rcu(&p
->hlist
, &ap
->hlist
);
1294 * This registers the second or subsequent kprobe at the same address.
1296 static int register_aggr_kprobe(struct kprobe
*orig_p
, struct kprobe
*p
)
1299 struct kprobe
*ap
= orig_p
;
1303 /* For preparing optimization, jump_label_text_reserved() is called */
1305 mutex_lock(&text_mutex
);
1307 if (!kprobe_aggrprobe(orig_p
)) {
1308 /* If 'orig_p' is not an 'aggr_kprobe', create new one. */
1309 ap
= alloc_aggr_kprobe(orig_p
);
1314 init_aggr_kprobe(ap
, orig_p
);
1315 } else if (kprobe_unused(ap
)) {
1316 /* This probe is going to die. Rescue it */
1317 ret
= reuse_unused_kprobe(ap
);
1322 if (kprobe_gone(ap
)) {
1324 * Attempting to insert new probe at the same location that
1325 * had a probe in the module vaddr area which already
1326 * freed. So, the instruction slot has already been
1327 * released. We need a new slot for the new probe.
1329 ret
= arch_prepare_kprobe(ap
);
1332 * Even if fail to allocate new slot, don't need to
1333 * free the 'ap'. It will be used next time, or
1334 * freed by unregister_kprobe().
1338 /* Prepare optimized instructions if possible. */
1339 prepare_optimized_kprobe(ap
);
1342 * Clear gone flag to prevent allocating new slot again, and
1343 * set disabled flag because it is not armed yet.
1345 ap
->flags
= (ap
->flags
& ~KPROBE_FLAG_GONE
)
1346 | KPROBE_FLAG_DISABLED
;
1349 /* Copy the insn slot of 'p' to 'ap'. */
1351 ret
= add_new_kprobe(ap
, p
);
1354 mutex_unlock(&text_mutex
);
1355 jump_label_unlock();
1358 if (ret
== 0 && kprobe_disabled(ap
) && !kprobe_disabled(p
)) {
1359 ap
->flags
&= ~KPROBE_FLAG_DISABLED
;
1360 if (!kprobes_all_disarmed
) {
1361 /* Arm the breakpoint again. */
1362 ret
= arm_kprobe(ap
);
1364 ap
->flags
|= KPROBE_FLAG_DISABLED
;
1365 list_del_rcu(&p
->list
);
1373 bool __weak
arch_within_kprobe_blacklist(unsigned long addr
)
1375 /* The '__kprobes' functions and entry code must not be probed. */
1376 return addr
>= (unsigned long)__kprobes_text_start
&&
1377 addr
< (unsigned long)__kprobes_text_end
;
1380 static bool __within_kprobe_blacklist(unsigned long addr
)
1382 struct kprobe_blacklist_entry
*ent
;
1384 if (arch_within_kprobe_blacklist(addr
))
1387 * If 'kprobe_blacklist' is defined, check the address and
1388 * reject any probe registration in the prohibited area.
1390 list_for_each_entry(ent
, &kprobe_blacklist
, list
) {
1391 if (addr
>= ent
->start_addr
&& addr
< ent
->end_addr
)
1397 bool within_kprobe_blacklist(unsigned long addr
)
1399 char symname
[KSYM_NAME_LEN
], *p
;
1401 if (__within_kprobe_blacklist(addr
))
1404 /* Check if the address is on a suffixed-symbol */
1405 if (!lookup_symbol_name(addr
, symname
)) {
1406 p
= strchr(symname
, '.');
1410 addr
= (unsigned long)kprobe_lookup_name(symname
, 0);
1412 return __within_kprobe_blacklist(addr
);
1418 * arch_adjust_kprobe_addr - adjust the address
1419 * @addr: symbol base address
1420 * @offset: offset within the symbol
1421 * @on_func_entry: was this @addr+@offset on the function entry
1423 * Typically returns @addr + @offset, except for special cases where the
1424 * function might be prefixed by a CFI landing pad, in that case any offset
1425 * inside the landing pad is mapped to the first 'real' instruction of the
1428 * Specifically, for things like IBT/BTI, skip the resp. ENDBR/BTI.C
1429 * instruction at +0.
1431 kprobe_opcode_t
*__weak
arch_adjust_kprobe_addr(unsigned long addr
,
1432 unsigned long offset
,
1433 bool *on_func_entry
)
1435 *on_func_entry
= !offset
;
1436 return (kprobe_opcode_t
*)(addr
+ offset
);
1440 * If 'symbol_name' is specified, look it up and add the 'offset'
1441 * to it. This way, we can specify a relative address to a symbol.
1442 * This returns encoded errors if it fails to look up symbol or invalid
1443 * combination of parameters.
1445 static kprobe_opcode_t
*
1446 _kprobe_addr(kprobe_opcode_t
*addr
, const char *symbol_name
,
1447 unsigned long offset
, bool *on_func_entry
)
1449 if ((symbol_name
&& addr
) || (!symbol_name
&& !addr
))
1454 * Input: @sym + @offset
1455 * Output: @addr + @offset
1457 * NOTE: kprobe_lookup_name() does *NOT* fold the offset
1458 * argument into it's output!
1460 addr
= kprobe_lookup_name(symbol_name
, offset
);
1462 return ERR_PTR(-ENOENT
);
1466 * So here we have @addr + @offset, displace it into a new
1467 * @addr' + @offset' where @addr' is the symbol start address.
1469 addr
= (void *)addr
+ offset
;
1470 if (!kallsyms_lookup_size_offset((unsigned long)addr
, NULL
, &offset
))
1471 return ERR_PTR(-ENOENT
);
1472 addr
= (void *)addr
- offset
;
1475 * Then ask the architecture to re-combine them, taking care of
1476 * magical function entry details while telling us if this was indeed
1477 * at the start of the function.
1479 addr
= arch_adjust_kprobe_addr((unsigned long)addr
, offset
, on_func_entry
);
1484 return ERR_PTR(-EINVAL
);
1487 static kprobe_opcode_t
*kprobe_addr(struct kprobe
*p
)
1490 return _kprobe_addr(p
->addr
, p
->symbol_name
, p
->offset
, &on_func_entry
);
1494 * Check the 'p' is valid and return the aggregator kprobe
1495 * at the same address.
1497 static struct kprobe
*__get_valid_kprobe(struct kprobe
*p
)
1499 struct kprobe
*ap
, *list_p
;
1501 lockdep_assert_held(&kprobe_mutex
);
1503 ap
= get_kprobe(p
->addr
);
1508 list_for_each_entry(list_p
, &ap
->list
, list
)
1510 /* kprobe p is a valid probe */
1519 * Warn and return error if the kprobe is being re-registered since
1520 * there must be a software bug.
1522 static inline int warn_kprobe_rereg(struct kprobe
*p
)
1526 mutex_lock(&kprobe_mutex
);
1527 if (WARN_ON_ONCE(__get_valid_kprobe(p
)))
1529 mutex_unlock(&kprobe_mutex
);
1534 static int check_ftrace_location(struct kprobe
*p
)
1536 unsigned long addr
= (unsigned long)p
->addr
;
1538 if (ftrace_location(addr
) == addr
) {
1539 #ifdef CONFIG_KPROBES_ON_FTRACE
1540 p
->flags
|= KPROBE_FLAG_FTRACE
;
1541 #else /* !CONFIG_KPROBES_ON_FTRACE */
1548 static bool is_cfi_preamble_symbol(unsigned long addr
)
1550 char symbuf
[KSYM_NAME_LEN
];
1552 if (lookup_symbol_name(addr
, symbuf
))
1555 return str_has_prefix("__cfi_", symbuf
) ||
1556 str_has_prefix("__pfx_", symbuf
);
1559 static int check_kprobe_address_safe(struct kprobe
*p
,
1560 struct module
**probed_mod
)
1564 ret
= check_ftrace_location(p
);
1570 /* Ensure it is not in reserved area nor out of text */
1571 if (!(core_kernel_text((unsigned long) p
->addr
) ||
1572 is_module_text_address((unsigned long) p
->addr
)) ||
1573 in_gate_area_no_mm((unsigned long) p
->addr
) ||
1574 within_kprobe_blacklist((unsigned long) p
->addr
) ||
1575 jump_label_text_reserved(p
->addr
, p
->addr
) ||
1576 static_call_text_reserved(p
->addr
, p
->addr
) ||
1577 find_bug((unsigned long)p
->addr
) ||
1578 is_cfi_preamble_symbol((unsigned long)p
->addr
)) {
1583 /* Check if 'p' is probing a module. */
1584 *probed_mod
= __module_text_address((unsigned long) p
->addr
);
1587 * We must hold a refcount of the probed module while updating
1588 * its code to prohibit unexpected unloading.
1590 if (unlikely(!try_module_get(*probed_mod
))) {
1596 * If the module freed '.init.text', we couldn't insert
1599 if (within_module_init((unsigned long)p
->addr
, *probed_mod
) &&
1600 (*probed_mod
)->state
!= MODULE_STATE_COMING
) {
1601 module_put(*probed_mod
);
1608 jump_label_unlock();
1613 int register_kprobe(struct kprobe
*p
)
1616 struct kprobe
*old_p
;
1617 struct module
*probed_mod
;
1618 kprobe_opcode_t
*addr
;
1621 /* Adjust probe address from symbol */
1622 addr
= _kprobe_addr(p
->addr
, p
->symbol_name
, p
->offset
, &on_func_entry
);
1624 return PTR_ERR(addr
);
1627 ret
= warn_kprobe_rereg(p
);
1631 /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
1632 p
->flags
&= KPROBE_FLAG_DISABLED
;
1634 INIT_LIST_HEAD(&p
->list
);
1636 ret
= check_kprobe_address_safe(p
, &probed_mod
);
1640 mutex_lock(&kprobe_mutex
);
1643 p
->flags
|= KPROBE_FLAG_ON_FUNC_ENTRY
;
1645 old_p
= get_kprobe(p
->addr
);
1647 /* Since this may unoptimize 'old_p', locking 'text_mutex'. */
1648 ret
= register_aggr_kprobe(old_p
, p
);
1653 /* Prevent text modification */
1654 mutex_lock(&text_mutex
);
1655 ret
= prepare_kprobe(p
);
1656 mutex_unlock(&text_mutex
);
1661 INIT_HLIST_NODE(&p
->hlist
);
1662 hlist_add_head_rcu(&p
->hlist
,
1663 &kprobe_table
[hash_ptr(p
->addr
, KPROBE_HASH_BITS
)]);
1665 if (!kprobes_all_disarmed
&& !kprobe_disabled(p
)) {
1666 ret
= arm_kprobe(p
);
1668 hlist_del_rcu(&p
->hlist
);
1674 /* Try to optimize kprobe */
1675 try_to_optimize_kprobe(p
);
1677 mutex_unlock(&kprobe_mutex
);
1680 module_put(probed_mod
);
1684 EXPORT_SYMBOL_GPL(register_kprobe
);
1686 /* Check if all probes on the 'ap' are disabled. */
1687 static bool aggr_kprobe_disabled(struct kprobe
*ap
)
1691 lockdep_assert_held(&kprobe_mutex
);
1693 list_for_each_entry(kp
, &ap
->list
, list
)
1694 if (!kprobe_disabled(kp
))
1696 * Since there is an active probe on the list,
1697 * we can't disable this 'ap'.
1704 static struct kprobe
*__disable_kprobe(struct kprobe
*p
)
1706 struct kprobe
*orig_p
;
1709 lockdep_assert_held(&kprobe_mutex
);
1711 /* Get an original kprobe for return */
1712 orig_p
= __get_valid_kprobe(p
);
1713 if (unlikely(orig_p
== NULL
))
1714 return ERR_PTR(-EINVAL
);
1716 if (!kprobe_disabled(p
)) {
1717 /* Disable probe if it is a child probe */
1719 p
->flags
|= KPROBE_FLAG_DISABLED
;
1721 /* Try to disarm and disable this/parent probe */
1722 if (p
== orig_p
|| aggr_kprobe_disabled(orig_p
)) {
1724 * Don't be lazy here. Even if 'kprobes_all_disarmed'
1725 * is false, 'orig_p' might not have been armed yet.
1726 * Note arm_all_kprobes() __tries__ to arm all kprobes
1727 * on the best effort basis.
1729 if (!kprobes_all_disarmed
&& !kprobe_disabled(orig_p
)) {
1730 ret
= disarm_kprobe(orig_p
, true);
1732 p
->flags
&= ~KPROBE_FLAG_DISABLED
;
1733 return ERR_PTR(ret
);
1736 orig_p
->flags
|= KPROBE_FLAG_DISABLED
;
1744 * Unregister a kprobe without a scheduler synchronization.
1746 static int __unregister_kprobe_top(struct kprobe
*p
)
1748 struct kprobe
*ap
, *list_p
;
1750 /* Disable kprobe. This will disarm it if needed. */
1751 ap
= __disable_kprobe(p
);
1757 * This probe is an independent(and non-optimized) kprobe
1758 * (not an aggrprobe). Remove from the hash list.
1762 /* Following process expects this probe is an aggrprobe */
1763 WARN_ON(!kprobe_aggrprobe(ap
));
1765 if (list_is_singular(&ap
->list
) && kprobe_disarmed(ap
))
1767 * !disarmed could be happen if the probe is under delayed
1772 /* If disabling probe has special handlers, update aggrprobe */
1773 if (p
->post_handler
&& !kprobe_gone(p
)) {
1774 list_for_each_entry(list_p
, &ap
->list
, list
) {
1775 if ((list_p
!= p
) && (list_p
->post_handler
))
1779 * For the kprobe-on-ftrace case, we keep the
1780 * post_handler setting to identify this aggrprobe
1781 * armed with kprobe_ipmodify_ops.
1783 if (!kprobe_ftrace(ap
))
1784 ap
->post_handler
= NULL
;
1788 * Remove from the aggrprobe: this path will do nothing in
1789 * __unregister_kprobe_bottom().
1791 list_del_rcu(&p
->list
);
1792 if (!kprobe_disabled(ap
) && !kprobes_all_disarmed
)
1794 * Try to optimize this probe again, because post
1795 * handler may have been changed.
1797 optimize_kprobe(ap
);
1802 hlist_del_rcu(&ap
->hlist
);
1806 static void __unregister_kprobe_bottom(struct kprobe
*p
)
1810 if (list_empty(&p
->list
))
1811 /* This is an independent kprobe */
1812 arch_remove_kprobe(p
);
1813 else if (list_is_singular(&p
->list
)) {
1814 /* This is the last child of an aggrprobe */
1815 ap
= list_entry(p
->list
.next
, struct kprobe
, list
);
1817 free_aggr_kprobe(ap
);
1819 /* Otherwise, do nothing. */
1822 int register_kprobes(struct kprobe
**kps
, int num
)
1828 for (i
= 0; i
< num
; i
++) {
1829 ret
= register_kprobe(kps
[i
]);
1832 unregister_kprobes(kps
, i
);
1838 EXPORT_SYMBOL_GPL(register_kprobes
);
1840 void unregister_kprobe(struct kprobe
*p
)
1842 unregister_kprobes(&p
, 1);
1844 EXPORT_SYMBOL_GPL(unregister_kprobe
);
1846 void unregister_kprobes(struct kprobe
**kps
, int num
)
1852 mutex_lock(&kprobe_mutex
);
1853 for (i
= 0; i
< num
; i
++)
1854 if (__unregister_kprobe_top(kps
[i
]) < 0)
1855 kps
[i
]->addr
= NULL
;
1856 mutex_unlock(&kprobe_mutex
);
1859 for (i
= 0; i
< num
; i
++)
1861 __unregister_kprobe_bottom(kps
[i
]);
1863 EXPORT_SYMBOL_GPL(unregister_kprobes
);
1865 int __weak
kprobe_exceptions_notify(struct notifier_block
*self
,
1866 unsigned long val
, void *data
)
1870 NOKPROBE_SYMBOL(kprobe_exceptions_notify
);
1872 static struct notifier_block kprobe_exceptions_nb
= {
1873 .notifier_call
= kprobe_exceptions_notify
,
1874 .priority
= 0x7fffffff /* we need to be notified first */
1877 #ifdef CONFIG_KRETPROBES
1879 #if !defined(CONFIG_KRETPROBE_ON_RETHOOK)
1881 /* callbacks for objpool of kretprobe instances */
1882 static int kretprobe_init_inst(void *nod
, void *context
)
1884 struct kretprobe_instance
*ri
= nod
;
1889 static int kretprobe_fini_pool(struct objpool_head
*head
, void *context
)
1895 static void free_rp_inst_rcu(struct rcu_head
*head
)
1897 struct kretprobe_instance
*ri
= container_of(head
, struct kretprobe_instance
, rcu
);
1898 struct kretprobe_holder
*rph
= ri
->rph
;
1900 objpool_drop(ri
, &rph
->pool
);
1902 NOKPROBE_SYMBOL(free_rp_inst_rcu
);
1904 static void recycle_rp_inst(struct kretprobe_instance
*ri
)
1906 struct kretprobe
*rp
= get_kretprobe(ri
);
1909 objpool_push(ri
, &rp
->rph
->pool
);
1911 call_rcu(&ri
->rcu
, free_rp_inst_rcu
);
1913 NOKPROBE_SYMBOL(recycle_rp_inst
);
1916 * This function is called from delayed_put_task_struct() when a task is
1917 * dead and cleaned up to recycle any kretprobe instances associated with
1918 * this task. These left over instances represent probed functions that
1919 * have been called but will never return.
1921 void kprobe_flush_task(struct task_struct
*tk
)
1923 struct kretprobe_instance
*ri
;
1924 struct llist_node
*node
;
1926 /* Early boot, not yet initialized. */
1927 if (unlikely(!kprobes_initialized
))
1930 kprobe_busy_begin();
1932 node
= __llist_del_all(&tk
->kretprobe_instances
);
1934 ri
= container_of(node
, struct kretprobe_instance
, llist
);
1937 recycle_rp_inst(ri
);
1942 NOKPROBE_SYMBOL(kprobe_flush_task
);
1944 static inline void free_rp_inst(struct kretprobe
*rp
)
1946 struct kretprobe_holder
*rph
= rp
->rph
;
1951 objpool_fini(&rph
->pool
);
1954 /* This assumes the 'tsk' is the current task or the is not running. */
1955 static kprobe_opcode_t
*__kretprobe_find_ret_addr(struct task_struct
*tsk
,
1956 struct llist_node
**cur
)
1958 struct kretprobe_instance
*ri
= NULL
;
1959 struct llist_node
*node
= *cur
;
1962 node
= tsk
->kretprobe_instances
.first
;
1967 ri
= container_of(node
, struct kretprobe_instance
, llist
);
1968 if (ri
->ret_addr
!= kretprobe_trampoline_addr()) {
1970 return ri
->ret_addr
;
1976 NOKPROBE_SYMBOL(__kretprobe_find_ret_addr
);
1979 * kretprobe_find_ret_addr -- Find correct return address modified by kretprobe
1981 * @fp: A frame pointer
1982 * @cur: a storage of the loop cursor llist_node pointer for next call
1984 * Find the correct return address modified by a kretprobe on @tsk in unsigned
1985 * long type. If it finds the return address, this returns that address value,
1986 * or this returns 0.
1987 * The @tsk must be 'current' or a task which is not running. @fp is a hint
1988 * to get the currect return address - which is compared with the
1989 * kretprobe_instance::fp field. The @cur is a loop cursor for searching the
1990 * kretprobe return addresses on the @tsk. The '*@cur' should be NULL at the
1991 * first call, but '@cur' itself must NOT NULL.
1993 unsigned long kretprobe_find_ret_addr(struct task_struct
*tsk
, void *fp
,
1994 struct llist_node
**cur
)
1996 struct kretprobe_instance
*ri
;
1997 kprobe_opcode_t
*ret
;
1999 if (WARN_ON_ONCE(!cur
))
2003 ret
= __kretprobe_find_ret_addr(tsk
, cur
);
2006 ri
= container_of(*cur
, struct kretprobe_instance
, llist
);
2007 } while (ri
->fp
!= fp
);
2009 return (unsigned long)ret
;
2011 NOKPROBE_SYMBOL(kretprobe_find_ret_addr
);
2013 void __weak
arch_kretprobe_fixup_return(struct pt_regs
*regs
,
2014 kprobe_opcode_t
*correct_ret_addr
)
2017 * Do nothing by default. Please fill this to update the fake return
2018 * address on the stack with the correct one on each arch if possible.
2022 unsigned long __kretprobe_trampoline_handler(struct pt_regs
*regs
,
2023 void *frame_pointer
)
2025 struct kretprobe_instance
*ri
= NULL
;
2026 struct llist_node
*first
, *node
= NULL
;
2027 kprobe_opcode_t
*correct_ret_addr
;
2028 struct kretprobe
*rp
;
2030 /* Find correct address and all nodes for this frame. */
2031 correct_ret_addr
= __kretprobe_find_ret_addr(current
, &node
);
2032 if (!correct_ret_addr
) {
2033 pr_err("kretprobe: Return address not found, not execute handler. Maybe there is a bug in the kernel.\n");
2038 * Set the return address as the instruction pointer, because if the
2039 * user handler calls stack_trace_save_regs() with this 'regs',
2040 * the stack trace will start from the instruction pointer.
2042 instruction_pointer_set(regs
, (unsigned long)correct_ret_addr
);
2044 /* Run the user handler of the nodes. */
2045 first
= current
->kretprobe_instances
.first
;
2047 ri
= container_of(first
, struct kretprobe_instance
, llist
);
2049 if (WARN_ON_ONCE(ri
->fp
!= frame_pointer
))
2052 rp
= get_kretprobe(ri
);
2053 if (rp
&& rp
->handler
) {
2054 struct kprobe
*prev
= kprobe_running();
2056 __this_cpu_write(current_kprobe
, &rp
->kp
);
2057 ri
->ret_addr
= correct_ret_addr
;
2058 rp
->handler(ri
, regs
);
2059 __this_cpu_write(current_kprobe
, prev
);
2064 first
= first
->next
;
2067 arch_kretprobe_fixup_return(regs
, correct_ret_addr
);
2069 /* Unlink all nodes for this frame. */
2070 first
= current
->kretprobe_instances
.first
;
2071 current
->kretprobe_instances
.first
= node
->next
;
2074 /* Recycle free instances. */
2076 ri
= container_of(first
, struct kretprobe_instance
, llist
);
2077 first
= first
->next
;
2079 recycle_rp_inst(ri
);
2082 return (unsigned long)correct_ret_addr
;
2084 NOKPROBE_SYMBOL(__kretprobe_trampoline_handler
)
2087 * This kprobe pre_handler is registered with every kretprobe. When probe
2088 * hits it will set up the return probe.
2090 static int pre_handler_kretprobe(struct kprobe
*p
, struct pt_regs
*regs
)
2092 struct kretprobe
*rp
= container_of(p
, struct kretprobe
, kp
);
2093 struct kretprobe_holder
*rph
= rp
->rph
;
2094 struct kretprobe_instance
*ri
;
2096 ri
= objpool_pop(&rph
->pool
);
2102 if (rp
->entry_handler
&& rp
->entry_handler(ri
, regs
)) {
2103 objpool_push(ri
, &rph
->pool
);
2107 arch_prepare_kretprobe(ri
, regs
);
2109 __llist_add(&ri
->llist
, ¤t
->kretprobe_instances
);
2113 NOKPROBE_SYMBOL(pre_handler_kretprobe
);
2114 #else /* CONFIG_KRETPROBE_ON_RETHOOK */
2116 * This kprobe pre_handler is registered with every kretprobe. When probe
2117 * hits it will set up the return probe.
2119 static int pre_handler_kretprobe(struct kprobe
*p
, struct pt_regs
*regs
)
2121 struct kretprobe
*rp
= container_of(p
, struct kretprobe
, kp
);
2122 struct kretprobe_instance
*ri
;
2123 struct rethook_node
*rhn
;
2125 rhn
= rethook_try_get(rp
->rh
);
2131 ri
= container_of(rhn
, struct kretprobe_instance
, node
);
2133 if (rp
->entry_handler
&& rp
->entry_handler(ri
, regs
))
2134 rethook_recycle(rhn
);
2136 rethook_hook(rhn
, regs
, kprobe_ftrace(p
));
2140 NOKPROBE_SYMBOL(pre_handler_kretprobe
);
2142 static void kretprobe_rethook_handler(struct rethook_node
*rh
, void *data
,
2143 unsigned long ret_addr
,
2144 struct pt_regs
*regs
)
2146 struct kretprobe
*rp
= (struct kretprobe
*)data
;
2147 struct kretprobe_instance
*ri
;
2148 struct kprobe_ctlblk
*kcb
;
2150 /* The data must NOT be null. This means rethook data structure is broken. */
2151 if (WARN_ON_ONCE(!data
) || !rp
->handler
)
2154 __this_cpu_write(current_kprobe
, &rp
->kp
);
2155 kcb
= get_kprobe_ctlblk();
2156 kcb
->kprobe_status
= KPROBE_HIT_ACTIVE
;
2158 ri
= container_of(rh
, struct kretprobe_instance
, node
);
2159 rp
->handler(ri
, regs
);
2161 __this_cpu_write(current_kprobe
, NULL
);
2163 NOKPROBE_SYMBOL(kretprobe_rethook_handler
);
2165 #endif /* !CONFIG_KRETPROBE_ON_RETHOOK */
2168 * kprobe_on_func_entry() -- check whether given address is function entry
2169 * @addr: Target address
2170 * @sym: Target symbol name
2171 * @offset: The offset from the symbol or the address
2173 * This checks whether the given @addr+@offset or @sym+@offset is on the
2174 * function entry address or not.
2175 * This returns 0 if it is the function entry, or -EINVAL if it is not.
2176 * And also it returns -ENOENT if it fails the symbol or address lookup.
2177 * Caller must pass @addr or @sym (either one must be NULL), or this
2180 int kprobe_on_func_entry(kprobe_opcode_t
*addr
, const char *sym
, unsigned long offset
)
2183 kprobe_opcode_t
*kp_addr
= _kprobe_addr(addr
, sym
, offset
, &on_func_entry
);
2185 if (IS_ERR(kp_addr
))
2186 return PTR_ERR(kp_addr
);
2194 int register_kretprobe(struct kretprobe
*rp
)
2200 ret
= kprobe_on_func_entry(rp
->kp
.addr
, rp
->kp
.symbol_name
, rp
->kp
.offset
);
2204 /* If only 'rp->kp.addr' is specified, check reregistering kprobes */
2205 if (rp
->kp
.addr
&& warn_kprobe_rereg(&rp
->kp
))
2208 if (kretprobe_blacklist_size
) {
2209 addr
= kprobe_addr(&rp
->kp
);
2211 return PTR_ERR(addr
);
2213 for (i
= 0; kretprobe_blacklist
[i
].name
!= NULL
; i
++) {
2214 if (kretprobe_blacklist
[i
].addr
== addr
)
2219 if (rp
->data_size
> KRETPROBE_MAX_DATA_SIZE
)
2222 rp
->kp
.pre_handler
= pre_handler_kretprobe
;
2223 rp
->kp
.post_handler
= NULL
;
2225 /* Pre-allocate memory for max kretprobe instances */
2226 if (rp
->maxactive
<= 0)
2227 rp
->maxactive
= max_t(unsigned int, 10, 2*num_possible_cpus());
2229 #ifdef CONFIG_KRETPROBE_ON_RETHOOK
2230 rp
->rh
= rethook_alloc((void *)rp
, kretprobe_rethook_handler
,
2231 sizeof(struct kretprobe_instance
) +
2232 rp
->data_size
, rp
->maxactive
);
2234 return PTR_ERR(rp
->rh
);
2237 /* Establish function entry probe point */
2238 ret
= register_kprobe(&rp
->kp
);
2240 rethook_free(rp
->rh
);
2243 #else /* !CONFIG_KRETPROBE_ON_RETHOOK */
2244 rp
->rph
= kzalloc(sizeof(struct kretprobe_holder
), GFP_KERNEL
);
2248 if (objpool_init(&rp
->rph
->pool
, rp
->maxactive
, rp
->data_size
+
2249 sizeof(struct kretprobe_instance
), GFP_KERNEL
,
2250 rp
->rph
, kretprobe_init_inst
, kretprobe_fini_pool
)) {
2255 rcu_assign_pointer(rp
->rph
->rp
, rp
);
2257 /* Establish function entry probe point */
2258 ret
= register_kprobe(&rp
->kp
);
2264 EXPORT_SYMBOL_GPL(register_kretprobe
);
2266 int register_kretprobes(struct kretprobe
**rps
, int num
)
2272 for (i
= 0; i
< num
; i
++) {
2273 ret
= register_kretprobe(rps
[i
]);
2276 unregister_kretprobes(rps
, i
);
2282 EXPORT_SYMBOL_GPL(register_kretprobes
);
2284 void unregister_kretprobe(struct kretprobe
*rp
)
2286 unregister_kretprobes(&rp
, 1);
2288 EXPORT_SYMBOL_GPL(unregister_kretprobe
);
2290 void unregister_kretprobes(struct kretprobe
**rps
, int num
)
2296 mutex_lock(&kprobe_mutex
);
2297 for (i
= 0; i
< num
; i
++) {
2298 if (__unregister_kprobe_top(&rps
[i
]->kp
) < 0)
2299 rps
[i
]->kp
.addr
= NULL
;
2300 #ifdef CONFIG_KRETPROBE_ON_RETHOOK
2301 rethook_free(rps
[i
]->rh
);
2303 rcu_assign_pointer(rps
[i
]->rph
->rp
, NULL
);
2306 mutex_unlock(&kprobe_mutex
);
2309 for (i
= 0; i
< num
; i
++) {
2310 if (rps
[i
]->kp
.addr
) {
2311 __unregister_kprobe_bottom(&rps
[i
]->kp
);
2312 #ifndef CONFIG_KRETPROBE_ON_RETHOOK
2313 free_rp_inst(rps
[i
]);
2318 EXPORT_SYMBOL_GPL(unregister_kretprobes
);
2320 #else /* CONFIG_KRETPROBES */
2321 int register_kretprobe(struct kretprobe
*rp
)
2325 EXPORT_SYMBOL_GPL(register_kretprobe
);
2327 int register_kretprobes(struct kretprobe
**rps
, int num
)
2331 EXPORT_SYMBOL_GPL(register_kretprobes
);
2333 void unregister_kretprobe(struct kretprobe
*rp
)
2336 EXPORT_SYMBOL_GPL(unregister_kretprobe
);
2338 void unregister_kretprobes(struct kretprobe
**rps
, int num
)
2341 EXPORT_SYMBOL_GPL(unregister_kretprobes
);
2343 static int pre_handler_kretprobe(struct kprobe
*p
, struct pt_regs
*regs
)
2347 NOKPROBE_SYMBOL(pre_handler_kretprobe
);
2349 #endif /* CONFIG_KRETPROBES */
2351 /* Set the kprobe gone and remove its instruction buffer. */
2352 static void kill_kprobe(struct kprobe
*p
)
2356 lockdep_assert_held(&kprobe_mutex
);
2359 * The module is going away. We should disarm the kprobe which
2360 * is using ftrace, because ftrace framework is still available at
2361 * 'MODULE_STATE_GOING' notification.
2363 if (kprobe_ftrace(p
) && !kprobe_disabled(p
) && !kprobes_all_disarmed
)
2364 disarm_kprobe_ftrace(p
);
2366 p
->flags
|= KPROBE_FLAG_GONE
;
2367 if (kprobe_aggrprobe(p
)) {
2369 * If this is an aggr_kprobe, we have to list all the
2370 * chained probes and mark them GONE.
2372 list_for_each_entry(kp
, &p
->list
, list
)
2373 kp
->flags
|= KPROBE_FLAG_GONE
;
2374 p
->post_handler
= NULL
;
2375 kill_optimized_kprobe(p
);
2378 * Here, we can remove insn_slot safely, because no thread calls
2379 * the original probed function (which will be freed soon) any more.
2381 arch_remove_kprobe(p
);
2384 /* Disable one kprobe */
2385 int disable_kprobe(struct kprobe
*kp
)
2390 mutex_lock(&kprobe_mutex
);
2392 /* Disable this kprobe */
2393 p
= __disable_kprobe(kp
);
2397 mutex_unlock(&kprobe_mutex
);
2400 EXPORT_SYMBOL_GPL(disable_kprobe
);
2402 /* Enable one kprobe */
2403 int enable_kprobe(struct kprobe
*kp
)
2408 mutex_lock(&kprobe_mutex
);
2410 /* Check whether specified probe is valid. */
2411 p
= __get_valid_kprobe(kp
);
2412 if (unlikely(p
== NULL
)) {
2417 if (kprobe_gone(kp
)) {
2418 /* This kprobe has gone, we couldn't enable it. */
2424 kp
->flags
&= ~KPROBE_FLAG_DISABLED
;
2426 if (!kprobes_all_disarmed
&& kprobe_disabled(p
)) {
2427 p
->flags
&= ~KPROBE_FLAG_DISABLED
;
2428 ret
= arm_kprobe(p
);
2430 p
->flags
|= KPROBE_FLAG_DISABLED
;
2432 kp
->flags
|= KPROBE_FLAG_DISABLED
;
2436 mutex_unlock(&kprobe_mutex
);
2439 EXPORT_SYMBOL_GPL(enable_kprobe
);
2441 /* Caller must NOT call this in usual path. This is only for critical case */
2442 void dump_kprobe(struct kprobe
*kp
)
2444 pr_err("Dump kprobe:\n.symbol_name = %s, .offset = %x, .addr = %pS\n",
2445 kp
->symbol_name
, kp
->offset
, kp
->addr
);
2447 NOKPROBE_SYMBOL(dump_kprobe
);
2449 int kprobe_add_ksym_blacklist(unsigned long entry
)
2451 struct kprobe_blacklist_entry
*ent
;
2452 unsigned long offset
= 0, size
= 0;
2454 if (!kernel_text_address(entry
) ||
2455 !kallsyms_lookup_size_offset(entry
, &size
, &offset
))
2458 ent
= kmalloc(sizeof(*ent
), GFP_KERNEL
);
2461 ent
->start_addr
= entry
;
2462 ent
->end_addr
= entry
+ size
;
2463 INIT_LIST_HEAD(&ent
->list
);
2464 list_add_tail(&ent
->list
, &kprobe_blacklist
);
2469 /* Add all symbols in given area into kprobe blacklist */
2470 int kprobe_add_area_blacklist(unsigned long start
, unsigned long end
)
2472 unsigned long entry
;
2475 for (entry
= start
; entry
< end
; entry
+= ret
) {
2476 ret
= kprobe_add_ksym_blacklist(entry
);
2479 if (ret
== 0) /* In case of alias symbol */
2485 /* Remove all symbols in given area from kprobe blacklist */
2486 static void kprobe_remove_area_blacklist(unsigned long start
, unsigned long end
)
2488 struct kprobe_blacklist_entry
*ent
, *n
;
2490 list_for_each_entry_safe(ent
, n
, &kprobe_blacklist
, list
) {
2491 if (ent
->start_addr
< start
|| ent
->start_addr
>= end
)
2493 list_del(&ent
->list
);
2498 static void kprobe_remove_ksym_blacklist(unsigned long entry
)
2500 kprobe_remove_area_blacklist(entry
, entry
+ 1);
2503 int __weak
arch_kprobe_get_kallsym(unsigned int *symnum
, unsigned long *value
,
2504 char *type
, char *sym
)
2509 int kprobe_get_kallsym(unsigned int symnum
, unsigned long *value
, char *type
,
2512 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
2513 if (!kprobe_cache_get_kallsym(&kprobe_insn_slots
, &symnum
, value
, type
, sym
))
2515 #ifdef CONFIG_OPTPROBES
2516 if (!kprobe_cache_get_kallsym(&kprobe_optinsn_slots
, &symnum
, value
, type
, sym
))
2520 if (!arch_kprobe_get_kallsym(&symnum
, value
, type
, sym
))
2525 int __init __weak
arch_populate_kprobe_blacklist(void)
2531 * Lookup and populate the kprobe_blacklist.
2533 * Unlike the kretprobe blacklist, we'll need to determine
2534 * the range of addresses that belong to the said functions,
2535 * since a kprobe need not necessarily be at the beginning
2538 static int __init
populate_kprobe_blacklist(unsigned long *start
,
2541 unsigned long entry
;
2542 unsigned long *iter
;
2545 for (iter
= start
; iter
< end
; iter
++) {
2546 entry
= (unsigned long)dereference_symbol_descriptor((void *)*iter
);
2547 ret
= kprobe_add_ksym_blacklist(entry
);
2554 /* Symbols in '__kprobes_text' are blacklisted */
2555 ret
= kprobe_add_area_blacklist((unsigned long)__kprobes_text_start
,
2556 (unsigned long)__kprobes_text_end
);
2560 /* Symbols in 'noinstr' section are blacklisted */
2561 ret
= kprobe_add_area_blacklist((unsigned long)__noinstr_text_start
,
2562 (unsigned long)__noinstr_text_end
);
2564 return ret
? : arch_populate_kprobe_blacklist();
2567 static void add_module_kprobe_blacklist(struct module
*mod
)
2569 unsigned long start
, end
;
2572 if (mod
->kprobe_blacklist
) {
2573 for (i
= 0; i
< mod
->num_kprobe_blacklist
; i
++)
2574 kprobe_add_ksym_blacklist(mod
->kprobe_blacklist
[i
]);
2577 start
= (unsigned long)mod
->kprobes_text_start
;
2579 end
= start
+ mod
->kprobes_text_size
;
2580 kprobe_add_area_blacklist(start
, end
);
2583 start
= (unsigned long)mod
->noinstr_text_start
;
2585 end
= start
+ mod
->noinstr_text_size
;
2586 kprobe_add_area_blacklist(start
, end
);
2590 static void remove_module_kprobe_blacklist(struct module
*mod
)
2592 unsigned long start
, end
;
2595 if (mod
->kprobe_blacklist
) {
2596 for (i
= 0; i
< mod
->num_kprobe_blacklist
; i
++)
2597 kprobe_remove_ksym_blacklist(mod
->kprobe_blacklist
[i
]);
2600 start
= (unsigned long)mod
->kprobes_text_start
;
2602 end
= start
+ mod
->kprobes_text_size
;
2603 kprobe_remove_area_blacklist(start
, end
);
2606 start
= (unsigned long)mod
->noinstr_text_start
;
2608 end
= start
+ mod
->noinstr_text_size
;
2609 kprobe_remove_area_blacklist(start
, end
);
2613 /* Module notifier call back, checking kprobes on the module */
2614 static int kprobes_module_callback(struct notifier_block
*nb
,
2615 unsigned long val
, void *data
)
2617 struct module
*mod
= data
;
2618 struct hlist_head
*head
;
2621 int checkcore
= (val
== MODULE_STATE_GOING
);
2623 if (val
== MODULE_STATE_COMING
) {
2624 mutex_lock(&kprobe_mutex
);
2625 add_module_kprobe_blacklist(mod
);
2626 mutex_unlock(&kprobe_mutex
);
2628 if (val
!= MODULE_STATE_GOING
&& val
!= MODULE_STATE_LIVE
)
2632 * When 'MODULE_STATE_GOING' was notified, both of module '.text' and
2633 * '.init.text' sections would be freed. When 'MODULE_STATE_LIVE' was
2634 * notified, only '.init.text' section would be freed. We need to
2635 * disable kprobes which have been inserted in the sections.
2637 mutex_lock(&kprobe_mutex
);
2638 for (i
= 0; i
< KPROBE_TABLE_SIZE
; i
++) {
2639 head
= &kprobe_table
[i
];
2640 hlist_for_each_entry(p
, head
, hlist
)
2641 if (within_module_init((unsigned long)p
->addr
, mod
) ||
2643 within_module_core((unsigned long)p
->addr
, mod
))) {
2645 * The vaddr this probe is installed will soon
2646 * be vfreed buy not synced to disk. Hence,
2647 * disarming the breakpoint isn't needed.
2649 * Note, this will also move any optimized probes
2650 * that are pending to be removed from their
2651 * corresponding lists to the 'freeing_list' and
2652 * will not be touched by the delayed
2653 * kprobe_optimizer() work handler.
2658 if (val
== MODULE_STATE_GOING
)
2659 remove_module_kprobe_blacklist(mod
);
2660 mutex_unlock(&kprobe_mutex
);
2664 static struct notifier_block kprobe_module_nb
= {
2665 .notifier_call
= kprobes_module_callback
,
2669 void kprobe_free_init_mem(void)
2671 void *start
= (void *)(&__init_begin
);
2672 void *end
= (void *)(&__init_end
);
2673 struct hlist_head
*head
;
2677 mutex_lock(&kprobe_mutex
);
2679 /* Kill all kprobes on initmem because the target code has been freed. */
2680 for (i
= 0; i
< KPROBE_TABLE_SIZE
; i
++) {
2681 head
= &kprobe_table
[i
];
2682 hlist_for_each_entry(p
, head
, hlist
) {
2683 if (start
<= (void *)p
->addr
&& (void *)p
->addr
< end
)
2688 mutex_unlock(&kprobe_mutex
);
2691 static int __init
init_kprobes(void)
2695 /* FIXME allocate the probe table, currently defined statically */
2696 /* initialize all list heads */
2697 for (i
= 0; i
< KPROBE_TABLE_SIZE
; i
++)
2698 INIT_HLIST_HEAD(&kprobe_table
[i
]);
2700 err
= populate_kprobe_blacklist(__start_kprobe_blacklist
,
2701 __stop_kprobe_blacklist
);
2703 pr_err("Failed to populate blacklist (error %d), kprobes not restricted, be careful using them!\n", err
);
2705 if (kretprobe_blacklist_size
) {
2706 /* lookup the function address from its name */
2707 for (i
= 0; kretprobe_blacklist
[i
].name
!= NULL
; i
++) {
2708 kretprobe_blacklist
[i
].addr
=
2709 kprobe_lookup_name(kretprobe_blacklist
[i
].name
, 0);
2710 if (!kretprobe_blacklist
[i
].addr
)
2711 pr_err("Failed to lookup symbol '%s' for kretprobe blacklist. Maybe the target function is removed or renamed.\n",
2712 kretprobe_blacklist
[i
].name
);
2716 /* By default, kprobes are armed */
2717 kprobes_all_disarmed
= false;
2719 #if defined(CONFIG_OPTPROBES) && defined(__ARCH_WANT_KPROBES_INSN_SLOT)
2720 /* Init 'kprobe_optinsn_slots' for allocation */
2721 kprobe_optinsn_slots
.insn_size
= MAX_OPTINSN_SIZE
;
2724 err
= arch_init_kprobes();
2726 err
= register_die_notifier(&kprobe_exceptions_nb
);
2728 err
= register_module_notifier(&kprobe_module_nb
);
2730 kprobes_initialized
= (err
== 0);
2731 kprobe_sysctls_init();
2734 early_initcall(init_kprobes
);
2736 #if defined(CONFIG_OPTPROBES)
2737 static int __init
init_optprobes(void)
2740 * Enable kprobe optimization - this kicks the optimizer which
2741 * depends on synchronize_rcu_tasks() and ksoftirqd, that is
2742 * not spawned in early initcall. So delay the optimization.
2744 optimize_all_kprobes();
2748 subsys_initcall(init_optprobes
);
2751 #ifdef CONFIG_DEBUG_FS
2752 static void report_probe(struct seq_file
*pi
, struct kprobe
*p
,
2753 const char *sym
, int offset
, char *modname
, struct kprobe
*pp
)
2756 void *addr
= p
->addr
;
2758 if (p
->pre_handler
== pre_handler_kretprobe
)
2763 if (!kallsyms_show_value(pi
->file
->f_cred
))
2767 seq_printf(pi
, "%px %s %s+0x%x %s ",
2768 addr
, kprobe_type
, sym
, offset
,
2769 (modname
? modname
: " "));
2770 else /* try to use %pS */
2771 seq_printf(pi
, "%px %s %pS ",
2772 addr
, kprobe_type
, p
->addr
);
2776 seq_printf(pi
, "%s%s%s%s\n",
2777 (kprobe_gone(p
) ? "[GONE]" : ""),
2778 ((kprobe_disabled(p
) && !kprobe_gone(p
)) ? "[DISABLED]" : ""),
2779 (kprobe_optimized(pp
) ? "[OPTIMIZED]" : ""),
2780 (kprobe_ftrace(pp
) ? "[FTRACE]" : ""));
2783 static void *kprobe_seq_start(struct seq_file
*f
, loff_t
*pos
)
2785 return (*pos
< KPROBE_TABLE_SIZE
) ? pos
: NULL
;
2788 static void *kprobe_seq_next(struct seq_file
*f
, void *v
, loff_t
*pos
)
2791 if (*pos
>= KPROBE_TABLE_SIZE
)
2796 static void kprobe_seq_stop(struct seq_file
*f
, void *v
)
2801 static int show_kprobe_addr(struct seq_file
*pi
, void *v
)
2803 struct hlist_head
*head
;
2804 struct kprobe
*p
, *kp
;
2806 unsigned int i
= *(loff_t
*) v
;
2807 unsigned long offset
= 0;
2808 char *modname
, namebuf
[KSYM_NAME_LEN
];
2810 head
= &kprobe_table
[i
];
2812 hlist_for_each_entry_rcu(p
, head
, hlist
) {
2813 sym
= kallsyms_lookup((unsigned long)p
->addr
, NULL
,
2814 &offset
, &modname
, namebuf
);
2815 if (kprobe_aggrprobe(p
)) {
2816 list_for_each_entry_rcu(kp
, &p
->list
, list
)
2817 report_probe(pi
, kp
, sym
, offset
, modname
, p
);
2819 report_probe(pi
, p
, sym
, offset
, modname
, NULL
);
2825 static const struct seq_operations kprobes_sops
= {
2826 .start
= kprobe_seq_start
,
2827 .next
= kprobe_seq_next
,
2828 .stop
= kprobe_seq_stop
,
2829 .show
= show_kprobe_addr
2832 DEFINE_SEQ_ATTRIBUTE(kprobes
);
2834 /* kprobes/blacklist -- shows which functions can not be probed */
2835 static void *kprobe_blacklist_seq_start(struct seq_file
*m
, loff_t
*pos
)
2837 mutex_lock(&kprobe_mutex
);
2838 return seq_list_start(&kprobe_blacklist
, *pos
);
2841 static void *kprobe_blacklist_seq_next(struct seq_file
*m
, void *v
, loff_t
*pos
)
2843 return seq_list_next(v
, &kprobe_blacklist
, pos
);
2846 static int kprobe_blacklist_seq_show(struct seq_file
*m
, void *v
)
2848 struct kprobe_blacklist_entry
*ent
=
2849 list_entry(v
, struct kprobe_blacklist_entry
, list
);
2852 * If '/proc/kallsyms' is not showing kernel address, we won't
2853 * show them here either.
2855 if (!kallsyms_show_value(m
->file
->f_cred
))
2856 seq_printf(m
, "0x%px-0x%px\t%ps\n", NULL
, NULL
,
2857 (void *)ent
->start_addr
);
2859 seq_printf(m
, "0x%px-0x%px\t%ps\n", (void *)ent
->start_addr
,
2860 (void *)ent
->end_addr
, (void *)ent
->start_addr
);
2864 static void kprobe_blacklist_seq_stop(struct seq_file
*f
, void *v
)
2866 mutex_unlock(&kprobe_mutex
);
2869 static const struct seq_operations kprobe_blacklist_sops
= {
2870 .start
= kprobe_blacklist_seq_start
,
2871 .next
= kprobe_blacklist_seq_next
,
2872 .stop
= kprobe_blacklist_seq_stop
,
2873 .show
= kprobe_blacklist_seq_show
,
2875 DEFINE_SEQ_ATTRIBUTE(kprobe_blacklist
);
2877 static int arm_all_kprobes(void)
2879 struct hlist_head
*head
;
2881 unsigned int i
, total
= 0, errors
= 0;
2884 mutex_lock(&kprobe_mutex
);
2886 /* If kprobes are armed, just return */
2887 if (!kprobes_all_disarmed
)
2888 goto already_enabled
;
2891 * optimize_kprobe() called by arm_kprobe() checks
2892 * kprobes_all_disarmed, so set kprobes_all_disarmed before
2895 kprobes_all_disarmed
= false;
2896 /* Arming kprobes doesn't optimize kprobe itself */
2897 for (i
= 0; i
< KPROBE_TABLE_SIZE
; i
++) {
2898 head
= &kprobe_table
[i
];
2899 /* Arm all kprobes on a best-effort basis */
2900 hlist_for_each_entry(p
, head
, hlist
) {
2901 if (!kprobe_disabled(p
)) {
2902 err
= arm_kprobe(p
);
2913 pr_warn("Kprobes globally enabled, but failed to enable %d out of %d probes. Please check which kprobes are kept disabled via debugfs.\n",
2916 pr_info("Kprobes globally enabled\n");
2919 mutex_unlock(&kprobe_mutex
);
2923 static int disarm_all_kprobes(void)
2925 struct hlist_head
*head
;
2927 unsigned int i
, total
= 0, errors
= 0;
2930 mutex_lock(&kprobe_mutex
);
2932 /* If kprobes are already disarmed, just return */
2933 if (kprobes_all_disarmed
) {
2934 mutex_unlock(&kprobe_mutex
);
2938 kprobes_all_disarmed
= true;
2940 for (i
= 0; i
< KPROBE_TABLE_SIZE
; i
++) {
2941 head
= &kprobe_table
[i
];
2942 /* Disarm all kprobes on a best-effort basis */
2943 hlist_for_each_entry(p
, head
, hlist
) {
2944 if (!arch_trampoline_kprobe(p
) && !kprobe_disabled(p
)) {
2945 err
= disarm_kprobe(p
, false);
2956 pr_warn("Kprobes globally disabled, but failed to disable %d out of %d probes. Please check which kprobes are kept enabled via debugfs.\n",
2959 pr_info("Kprobes globally disabled\n");
2961 mutex_unlock(&kprobe_mutex
);
2963 /* Wait for disarming all kprobes by optimizer */
2964 wait_for_kprobe_optimizer();
2970 * XXX: The debugfs bool file interface doesn't allow for callbacks
2971 * when the bool state is switched. We can reuse that facility when
2974 static ssize_t
read_enabled_file_bool(struct file
*file
,
2975 char __user
*user_buf
, size_t count
, loff_t
*ppos
)
2979 if (!kprobes_all_disarmed
)
2985 return simple_read_from_buffer(user_buf
, count
, ppos
, buf
, 2);
2988 static ssize_t
write_enabled_file_bool(struct file
*file
,
2989 const char __user
*user_buf
, size_t count
, loff_t
*ppos
)
2994 ret
= kstrtobool_from_user(user_buf
, count
, &enable
);
2998 ret
= enable
? arm_all_kprobes() : disarm_all_kprobes();
3005 static const struct file_operations fops_kp
= {
3006 .read
= read_enabled_file_bool
,
3007 .write
= write_enabled_file_bool
,
3008 .llseek
= default_llseek
,
3011 static int __init
debugfs_kprobe_init(void)
3015 dir
= debugfs_create_dir("kprobes", NULL
);
3017 debugfs_create_file("list", 0400, dir
, NULL
, &kprobes_fops
);
3019 debugfs_create_file("enabled", 0600, dir
, NULL
, &fops_kp
);
3021 debugfs_create_file("blacklist", 0400, dir
, NULL
,
3022 &kprobe_blacklist_fops
);
3027 late_initcall(debugfs_kprobe_init
);
3028 #endif /* CONFIG_DEBUG_FS */