Loading...
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Kernel Probes (KProbes)
4 *
5 * Copyright (C) IBM Corporation, 2002, 2004
6 *
7 * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
8 * Probes initial implementation (includes suggestions from
9 * Rusty Russell).
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.
19 */
20
21#define pr_fmt(fmt) "kprobes: " fmt
22
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>
42
43#include <asm/sections.h>
44#include <asm/cacheflush.h>
45#include <asm/errno.h>
46#include <linux/uaccess.h>
47
48#define KPROBE_HASH_BITS 6
49#define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
50
51#if !defined(CONFIG_OPTPROBES) || !defined(CONFIG_SYSCTL)
52#define kprobe_sysctls_init() do { } while (0)
53#endif
54
55static int kprobes_initialized;
56/* kprobe_table can be accessed by
57 * - Normal hlist traversal and RCU add/del under 'kprobe_mutex' is held.
58 * Or
59 * - RCU hlist traversal under disabling preempt (breakpoint handlers)
60 */
61static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
62
63/* NOTE: change this value only with 'kprobe_mutex' held */
64static bool kprobes_all_disarmed;
65
66/* This protects 'kprobe_table' and 'optimizing_list' */
67static DEFINE_MUTEX(kprobe_mutex);
68static DEFINE_PER_CPU(struct kprobe *, kprobe_instance);
69
70kprobe_opcode_t * __weak kprobe_lookup_name(const char *name,
71 unsigned int __unused)
72{
73 return ((kprobe_opcode_t *)(kallsyms_lookup_name(name)));
74}
75
76/*
77 * Blacklist -- list of 'struct kprobe_blacklist_entry' to store info where
78 * kprobes can not probe.
79 */
80static LIST_HEAD(kprobe_blacklist);
81
82#ifdef __ARCH_WANT_KPROBES_INSN_SLOT
83/*
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
88 */
89struct kprobe_insn_page {
90 struct list_head list;
91 kprobe_opcode_t *insns; /* Page of instruction slots */
92 struct kprobe_insn_cache *cache;
93 int nused;
94 int ngarbage;
95 char slot_used[];
96};
97
98#define KPROBE_INSN_PAGE_SIZE(slots) \
99 (offsetof(struct kprobe_insn_page, slot_used) + \
100 (sizeof(char) * (slots)))
101
102static int slots_per_page(struct kprobe_insn_cache *c)
103{
104 return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));
105}
106
107enum kprobe_slot_state {
108 SLOT_CLEAN = 0,
109 SLOT_DIRTY = 1,
110 SLOT_USED = 2,
111};
112
113void __weak *alloc_insn_page(void)
114{
115 /*
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.)
120 */
121 return module_alloc(PAGE_SIZE);
122}
123
124static void free_insn_page(void *page)
125{
126 module_memfree(page);
127}
128
129struct 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,
136 .nr_garbage = 0,
137};
138static int collect_garbage_slots(struct kprobe_insn_cache *c);
139
140/**
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.
143 */
144kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c)
145{
146 struct kprobe_insn_page *kip;
147 kprobe_opcode_t *slot = NULL;
148
149 /* Since the slot array is not protected by rcu, we need a mutex */
150 mutex_lock(&c->mutex);
151 retry:
152 rcu_read_lock();
153 list_for_each_entry_rcu(kip, &c->pages, list) {
154 if (kip->nused < slots_per_page(c)) {
155 int i;
156
157 for (i = 0; i < slots_per_page(c); i++) {
158 if (kip->slot_used[i] == SLOT_CLEAN) {
159 kip->slot_used[i] = SLOT_USED;
160 kip->nused++;
161 slot = kip->insns + (i * c->insn_size);
162 rcu_read_unlock();
163 goto out;
164 }
165 }
166 /* kip->nused is broken. Fix it. */
167 kip->nused = slots_per_page(c);
168 WARN_ON(1);
169 }
170 }
171 rcu_read_unlock();
172
173 /* If there are any garbage slots, collect it and try again. */
174 if (c->nr_garbage && collect_garbage_slots(c) == 0)
175 goto retry;
176
177 /* All out of space. Need to allocate a new page. */
178 kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
179 if (!kip)
180 goto out;
181
182 kip->insns = c->alloc();
183 if (!kip->insns) {
184 kfree(kip);
185 goto out;
186 }
187 INIT_LIST_HEAD(&kip->list);
188 memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c));
189 kip->slot_used[0] = SLOT_USED;
190 kip->nused = 1;
191 kip->ngarbage = 0;
192 kip->cache = c;
193 list_add_rcu(&kip->list, &c->pages);
194 slot = kip->insns;
195
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);
199out:
200 mutex_unlock(&c->mutex);
201 return slot;
202}
203
204/* Return true if all garbages are collected, otherwise false. */
205static bool collect_one_slot(struct kprobe_insn_page *kip, int idx)
206{
207 kip->slot_used[idx] = SLOT_CLEAN;
208 kip->nused--;
209 if (kip->nused == 0) {
210 /*
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.
215 */
216 if (!list_is_singular(&kip->list)) {
217 /*
218 * Record perf ksymbol unregister event before removing
219 * the page.
220 */
221 perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL,
222 (unsigned long)kip->insns, PAGE_SIZE, true,
223 kip->cache->sym);
224 list_del_rcu(&kip->list);
225 synchronize_rcu();
226 kip->cache->free(kip->insns);
227 kfree(kip);
228 }
229 return true;
230 }
231 return false;
232}
233
234static int collect_garbage_slots(struct kprobe_insn_cache *c)
235{
236 struct kprobe_insn_page *kip, *next;
237
238 /* Ensure no-one is interrupted on the garbages */
239 synchronize_rcu();
240
241 list_for_each_entry_safe(kip, next, &c->pages, list) {
242 int i;
243
244 if (kip->ngarbage == 0)
245 continue;
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))
249 break;
250 }
251 }
252 c->nr_garbage = 0;
253 return 0;
254}
255
256void __free_insn_slot(struct kprobe_insn_cache *c,
257 kprobe_opcode_t *slot, int dirty)
258{
259 struct kprobe_insn_page *kip;
260 long idx;
261
262 mutex_lock(&c->mutex);
263 rcu_read_lock();
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))
268 goto out;
269 }
270 /* Could not find this slot. */
271 WARN_ON(1);
272 kip = NULL;
273out:
274 rcu_read_unlock();
275 /* Mark and sweep: this may sleep */
276 if (kip) {
277 /* Check double free */
278 WARN_ON(kip->slot_used[idx] != SLOT_USED);
279 if (dirty) {
280 kip->slot_used[idx] = SLOT_DIRTY;
281 kip->ngarbage++;
282 if (++c->nr_garbage > slots_per_page(c))
283 collect_garbage_slots(c);
284 } else {
285 collect_one_slot(kip, idx);
286 }
287 }
288 mutex_unlock(&c->mutex);
289}
290
291/*
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.
295 */
296bool __is_insn_slot_addr(struct kprobe_insn_cache *c, unsigned long addr)
297{
298 struct kprobe_insn_page *kip;
299 bool ret = false;
300
301 rcu_read_lock();
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) {
305 ret = true;
306 break;
307 }
308 }
309 rcu_read_unlock();
310
311 return ret;
312}
313
314int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum,
315 unsigned long *value, char *type, char *sym)
316{
317 struct kprobe_insn_page *kip;
318 int ret = -ERANGE;
319
320 rcu_read_lock();
321 list_for_each_entry_rcu(kip, &c->pages, list) {
322 if ((*symnum)--)
323 continue;
324 strscpy(sym, c->sym, KSYM_NAME_LEN);
325 *type = 't';
326 *value = (unsigned long)kip->insns;
327 ret = 0;
328 break;
329 }
330 rcu_read_unlock();
331
332 return ret;
333}
334
335#ifdef CONFIG_OPTPROBES
336void __weak *alloc_optinsn_page(void)
337{
338 return alloc_insn_page();
339}
340
341void __weak free_optinsn_page(void *page)
342{
343 free_insn_page(page);
344}
345
346/* For optimized_kprobe buffer */
347struct 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 */
354 .nr_garbage = 0,
355};
356#endif
357#endif
358
359/* We have preemption disabled.. so it is safe to use __ versions */
360static inline void set_kprobe_instance(struct kprobe *kp)
361{
362 __this_cpu_write(kprobe_instance, kp);
363}
364
365static inline void reset_kprobe_instance(void)
366{
367 __this_cpu_write(kprobe_instance, NULL);
368}
369
370/*
371 * This routine is called either:
372 * - under the 'kprobe_mutex' - during kprobe_[un]register().
373 * OR
374 * - with preemption disabled - from architecture specific code.
375 */
376struct kprobe *get_kprobe(void *addr)
377{
378 struct hlist_head *head;
379 struct kprobe *p;
380
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)) {
384 if (p->addr == addr)
385 return p;
386 }
387
388 return NULL;
389}
390NOKPROBE_SYMBOL(get_kprobe);
391
392static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs);
393
394/* Return true if 'p' is an aggregator */
395static inline bool kprobe_aggrprobe(struct kprobe *p)
396{
397 return p->pre_handler == aggr_pre_handler;
398}
399
400/* Return true if 'p' is unused */
401static inline bool kprobe_unused(struct kprobe *p)
402{
403 return kprobe_aggrprobe(p) && kprobe_disabled(p) &&
404 list_empty(&p->list);
405}
406
407/* Keep all fields in the kprobe consistent. */
408static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p)
409{
410 memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t));
411 memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn));
412}
413
414#ifdef CONFIG_OPTPROBES
415/* NOTE: This is protected by 'kprobe_mutex'. */
416static bool kprobes_allow_optimization;
417
418/*
419 * Call all 'kprobe::pre_handler' on the list, but ignores its return value.
420 * This must be called from arch-dep optimized caller.
421 */
422void opt_pre_handler(struct kprobe *p, struct pt_regs *regs)
423{
424 struct kprobe *kp;
425
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);
430 }
431 reset_kprobe_instance();
432 }
433}
434NOKPROBE_SYMBOL(opt_pre_handler);
435
436/* Free optimized instructions and optimized_kprobe */
437static void free_aggr_kprobe(struct kprobe *p)
438{
439 struct optimized_kprobe *op;
440
441 op = container_of(p, struct optimized_kprobe, kp);
442 arch_remove_optimized_kprobe(op);
443 arch_remove_kprobe(p);
444 kfree(op);
445}
446
447/* Return true if the kprobe is ready for optimization. */
448static inline int kprobe_optready(struct kprobe *p)
449{
450 struct optimized_kprobe *op;
451
452 if (kprobe_aggrprobe(p)) {
453 op = container_of(p, struct optimized_kprobe, kp);
454 return arch_prepared_optinsn(&op->optinsn);
455 }
456
457 return 0;
458}
459
460/* Return true if the kprobe is disarmed. Note: p must be on hash list */
461bool kprobe_disarmed(struct kprobe *p)
462{
463 struct optimized_kprobe *op;
464
465 /* If kprobe is not aggr/opt probe, just return kprobe is disabled */
466 if (!kprobe_aggrprobe(p))
467 return kprobe_disabled(p);
468
469 op = container_of(p, struct optimized_kprobe, kp);
470
471 return kprobe_disabled(p) && list_empty(&op->list);
472}
473
474/* Return true if the probe is queued on (un)optimizing lists */
475static bool kprobe_queued(struct kprobe *p)
476{
477 struct optimized_kprobe *op;
478
479 if (kprobe_aggrprobe(p)) {
480 op = container_of(p, struct optimized_kprobe, kp);
481 if (!list_empty(&op->list))
482 return true;
483 }
484 return false;
485}
486
487/*
488 * Return an optimized kprobe whose optimizing code replaces
489 * instructions including 'addr' (exclude breakpoint).
490 */
491static struct kprobe *get_optimized_kprobe(kprobe_opcode_t *addr)
492{
493 int i;
494 struct kprobe *p = NULL;
495 struct optimized_kprobe *op;
496
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);
500
501 if (p && kprobe_optready(p)) {
502 op = container_of(p, struct optimized_kprobe, kp);
503 if (arch_within_optimized_kprobe(op, addr))
504 return p;
505 }
506
507 return NULL;
508}
509
510/* Optimization staging list, protected by 'kprobe_mutex' */
511static LIST_HEAD(optimizing_list);
512static LIST_HEAD(unoptimizing_list);
513static LIST_HEAD(freeing_list);
514
515static void kprobe_optimizer(struct work_struct *work);
516static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
517#define OPTIMIZE_DELAY 5
518
519/*
520 * Optimize (replace a breakpoint with a jump) kprobes listed on
521 * 'optimizing_list'.
522 */
523static void do_optimize_kprobes(void)
524{
525 lockdep_assert_held(&text_mutex);
526 /*
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.
535 */
536 lockdep_assert_cpus_held();
537
538 /* Optimization never be done when disarmed */
539 if (kprobes_all_disarmed || !kprobes_allow_optimization ||
540 list_empty(&optimizing_list))
541 return;
542
543 arch_optimize_kprobes(&optimizing_list);
544}
545
546/*
547 * Unoptimize (replace a jump with a breakpoint and remove the breakpoint
548 * if need) kprobes listed on 'unoptimizing_list'.
549 */
550static void do_unoptimize_kprobes(void)
551{
552 struct optimized_kprobe *op, *tmp;
553
554 lockdep_assert_held(&text_mutex);
555 /* See comment in do_optimize_kprobes() */
556 lockdep_assert_cpus_held();
557
558 if (!list_empty(&unoptimizing_list))
559 arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list);
560
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)) {
569 /*
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().)
573 */
574 hlist_del_rcu(&op->kp.hlist);
575 } else
576 list_del_init(&op->list);
577 }
578}
579
580/* Reclaim all kprobes on the 'freeing_list' */
581static void do_free_cleaned_kprobes(void)
582{
583 struct optimized_kprobe *op, *tmp;
584
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))) {
588 /*
589 * This must not happen, but if there is a kprobe
590 * still in use, keep it on kprobes hash list.
591 */
592 continue;
593 }
594 free_aggr_kprobe(&op->kp);
595 }
596}
597
598/* Start optimizer after OPTIMIZE_DELAY passed */
599static void kick_kprobe_optimizer(void)
600{
601 schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
602}
603
604/* Kprobe jump optimizer */
605static void kprobe_optimizer(struct work_struct *work)
606{
607 mutex_lock(&kprobe_mutex);
608 cpus_read_lock();
609 mutex_lock(&text_mutex);
610
611 /*
612 * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
613 * kprobes before waiting for quiesence period.
614 */
615 do_unoptimize_kprobes();
616
617 /*
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.
625 */
626 synchronize_rcu_tasks();
627
628 /* Step 3: Optimize kprobes after quiesence period */
629 do_optimize_kprobes();
630
631 /* Step 4: Free cleaned kprobes after quiesence period */
632 do_free_cleaned_kprobes();
633
634 mutex_unlock(&text_mutex);
635 cpus_read_unlock();
636
637 /* Step 5: Kick optimizer again if needed */
638 if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
639 kick_kprobe_optimizer();
640
641 mutex_unlock(&kprobe_mutex);
642}
643
644/* Wait for completing optimization and unoptimization */
645void wait_for_kprobe_optimizer(void)
646{
647 mutex_lock(&kprobe_mutex);
648
649 while (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) {
650 mutex_unlock(&kprobe_mutex);
651
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 */
655 cpu_relax();
656
657 mutex_lock(&kprobe_mutex);
658 }
659
660 mutex_unlock(&kprobe_mutex);
661}
662
663bool optprobe_queued_unopt(struct optimized_kprobe *op)
664{
665 struct optimized_kprobe *_op;
666
667 list_for_each_entry(_op, &unoptimizing_list, list) {
668 if (op == _op)
669 return true;
670 }
671
672 return false;
673}
674
675/* Optimize kprobe if p is ready to be optimized */
676static void optimize_kprobe(struct kprobe *p)
677{
678 struct optimized_kprobe *op;
679
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))
683 return;
684
685 /* kprobes with 'post_handler' can not be optimized */
686 if (p->post_handler)
687 return;
688
689 op = container_of(p, struct optimized_kprobe, kp);
690
691 /* Check there is no other kprobes at the optimized instructions */
692 if (arch_check_optimized_kprobe(op) < 0)
693 return;
694
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);
700 }
701 return;
702 }
703 op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
704
705 /*
706 * On the 'unoptimizing_list' and 'optimizing_list',
707 * 'op' must have OPTIMIZED flag
708 */
709 if (WARN_ON_ONCE(!list_empty(&op->list)))
710 return;
711
712 list_add(&op->list, &optimizing_list);
713 kick_kprobe_optimizer();
714}
715
716/* Short cut to direct unoptimizing */
717static void force_unoptimize_kprobe(struct optimized_kprobe *op)
718{
719 lockdep_assert_cpus_held();
720 arch_unoptimize_kprobe(op);
721 op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
722}
723
724/* Unoptimize a kprobe if p is optimized */
725static void unoptimize_kprobe(struct kprobe *p, bool force)
726{
727 struct optimized_kprobe *op;
728
729 if (!kprobe_aggrprobe(p) || kprobe_disarmed(p))
730 return; /* This is not an optprobe nor optimized */
731
732 op = container_of(p, struct optimized_kprobe, kp);
733 if (!kprobe_optimized(p))
734 return;
735
736 if (!list_empty(&op->list)) {
737 if (optprobe_queued_unopt(op)) {
738 /* Queued in unoptimizing queue */
739 if (force) {
740 /*
741 * Forcibly unoptimize the kprobe here, and queue it
742 * in the freeing list for release afterwards.
743 */
744 force_unoptimize_kprobe(op);
745 list_move(&op->list, &freeing_list);
746 }
747 } else {
748 /* Dequeue from the optimizing queue */
749 list_del_init(&op->list);
750 op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
751 }
752 return;
753 }
754
755 /* Optimized kprobe case */
756 if (force) {
757 /* Forcibly update the code: this is a special case */
758 force_unoptimize_kprobe(op);
759 } else {
760 list_add(&op->list, &unoptimizing_list);
761 kick_kprobe_optimizer();
762 }
763}
764
765/* Cancel unoptimizing for reusing */
766static int reuse_unused_kprobe(struct kprobe *ap)
767{
768 struct optimized_kprobe *op;
769
770 /*
771 * Unused kprobe MUST be on the way of delayed unoptimizing (means
772 * there is still a relative jump) and disabled.
773 */
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))
780 return -EINVAL;
781
782 optimize_kprobe(ap);
783 return 0;
784}
785
786/* Remove optimized instructions */
787static void kill_optimized_kprobe(struct kprobe *p)
788{
789 struct optimized_kprobe *op;
790
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;
796
797 if (kprobe_unused(p)) {
798 /*
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.
802 */
803 if (optprobe_queued_unopt(op))
804 list_move(&op->list, &freeing_list);
805 }
806
807 /* Don't touch the code, because it is already freed. */
808 arch_remove_optimized_kprobe(op);
809}
810
811static inline
812void __prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
813{
814 if (!kprobe_ftrace(p))
815 arch_prepare_optimized_kprobe(op, p);
816}
817
818/* Try to prepare optimized instructions */
819static void prepare_optimized_kprobe(struct kprobe *p)
820{
821 struct optimized_kprobe *op;
822
823 op = container_of(p, struct optimized_kprobe, kp);
824 __prepare_optimized_kprobe(op, p);
825}
826
827/* Allocate new optimized_kprobe and try to prepare optimized instructions. */
828static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
829{
830 struct optimized_kprobe *op;
831
832 op = kzalloc(sizeof(struct optimized_kprobe), GFP_KERNEL);
833 if (!op)
834 return NULL;
835
836 INIT_LIST_HEAD(&op->list);
837 op->kp.addr = p->addr;
838 __prepare_optimized_kprobe(op, p);
839
840 return &op->kp;
841}
842
843static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p);
844
845/*
846 * Prepare an optimized_kprobe and optimize it.
847 * NOTE: 'p' must be a normal registered kprobe.
848 */
849static void try_to_optimize_kprobe(struct kprobe *p)
850{
851 struct kprobe *ap;
852 struct optimized_kprobe *op;
853
854 /* Impossible to optimize ftrace-based kprobe. */
855 if (kprobe_ftrace(p))
856 return;
857
858 /* For preparing optimization, jump_label_text_reserved() is called. */
859 cpus_read_lock();
860 jump_label_lock();
861 mutex_lock(&text_mutex);
862
863 ap = alloc_aggr_kprobe(p);
864 if (!ap)
865 goto out;
866
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);
871 kfree(op);
872 goto out;
873 }
874
875 init_aggr_kprobe(ap, p);
876 optimize_kprobe(ap); /* This just kicks optimizer thread. */
877
878out:
879 mutex_unlock(&text_mutex);
880 jump_label_unlock();
881 cpus_read_unlock();
882}
883
884static void optimize_all_kprobes(void)
885{
886 struct hlist_head *head;
887 struct kprobe *p;
888 unsigned int i;
889
890 mutex_lock(&kprobe_mutex);
891 /* If optimization is already allowed, just return. */
892 if (kprobes_allow_optimization)
893 goto out;
894
895 cpus_read_lock();
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))
901 optimize_kprobe(p);
902 }
903 cpus_read_unlock();
904 pr_info("kprobe jump-optimization is enabled. All kprobes are optimized if possible.\n");
905out:
906 mutex_unlock(&kprobe_mutex);
907}
908
909#ifdef CONFIG_SYSCTL
910static void unoptimize_all_kprobes(void)
911{
912 struct hlist_head *head;
913 struct kprobe *p;
914 unsigned int i;
915
916 mutex_lock(&kprobe_mutex);
917 /* If optimization is already prohibited, just return. */
918 if (!kprobes_allow_optimization) {
919 mutex_unlock(&kprobe_mutex);
920 return;
921 }
922
923 cpus_read_lock();
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);
930 }
931 }
932 cpus_read_unlock();
933 mutex_unlock(&kprobe_mutex);
934
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");
938}
939
940static DEFINE_MUTEX(kprobe_sysctl_mutex);
941static int sysctl_kprobes_optimization;
942static int proc_kprobes_optimization_handler(struct ctl_table *table,
943 int write, void *buffer,
944 size_t *length, loff_t *ppos)
945{
946 int ret;
947
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);
951
952 if (sysctl_kprobes_optimization)
953 optimize_all_kprobes();
954 else
955 unoptimize_all_kprobes();
956 mutex_unlock(&kprobe_sysctl_mutex);
957
958 return ret;
959}
960
961static struct ctl_table kprobe_sysctls[] = {
962 {
963 .procname = "kprobes-optimization",
964 .data = &sysctl_kprobes_optimization,
965 .maxlen = sizeof(int),
966 .mode = 0644,
967 .proc_handler = proc_kprobes_optimization_handler,
968 .extra1 = SYSCTL_ZERO,
969 .extra2 = SYSCTL_ONE,
970 },
971 {}
972};
973
974static void __init kprobe_sysctls_init(void)
975{
976 register_sysctl_init("debug", kprobe_sysctls);
977}
978#endif /* CONFIG_SYSCTL */
979
980/* Put a breakpoint for a probe. */
981static void __arm_kprobe(struct kprobe *p)
982{
983 struct kprobe *_p;
984
985 lockdep_assert_held(&text_mutex);
986
987 /* Find the overlapping optimized kprobes. */
988 _p = get_optimized_kprobe(p->addr);
989 if (unlikely(_p))
990 /* Fallback to unoptimized kprobe */
991 unoptimize_kprobe(_p, true);
992
993 arch_arm_kprobe(p);
994 optimize_kprobe(p); /* Try to optimize (add kprobe to a list) */
995}
996
997/* Remove the breakpoint of a probe. */
998static void __disarm_kprobe(struct kprobe *p, bool reopt)
999{
1000 struct kprobe *_p;
1001
1002 lockdep_assert_held(&text_mutex);
1003
1004 /* Try to unoptimize */
1005 unoptimize_kprobe(p, kprobes_all_disarmed);
1006
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);
1013 }
1014 /*
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.
1019 */
1020}
1021
1022#else /* !CONFIG_OPTPROBES */
1023
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)
1033
1034static int reuse_unused_kprobe(struct kprobe *ap)
1035{
1036 /*
1037 * If the optimized kprobe is NOT supported, the aggr kprobe is
1038 * released at the same time that the last aggregated kprobe is
1039 * unregistered.
1040 * Thus there should be no chance to reuse unused kprobe.
1041 */
1042 WARN_ON_ONCE(1);
1043 return -EINVAL;
1044}
1045
1046static void free_aggr_kprobe(struct kprobe *p)
1047{
1048 arch_remove_kprobe(p);
1049 kfree(p);
1050}
1051
1052static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
1053{
1054 return kzalloc(sizeof(struct kprobe), GFP_KERNEL);
1055}
1056#endif /* CONFIG_OPTPROBES */
1057
1058#ifdef CONFIG_KPROBES_ON_FTRACE
1059static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
1060 .func = kprobe_ftrace_handler,
1061 .flags = FTRACE_OPS_FL_SAVE_REGS,
1062};
1063
1064static struct ftrace_ops kprobe_ipmodify_ops __read_mostly = {
1065 .func = kprobe_ftrace_handler,
1066 .flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_IPMODIFY,
1067};
1068
1069static int kprobe_ipmodify_enabled;
1070static int kprobe_ftrace_enabled;
1071
1072static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
1073 int *cnt)
1074{
1075 int ret;
1076
1077 lockdep_assert_held(&kprobe_mutex);
1078
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))
1081 return ret;
1082
1083 if (*cnt == 0) {
1084 ret = register_ftrace_function(ops);
1085 if (WARN(ret < 0, "Failed to register kprobe-ftrace (error %d)\n", ret))
1086 goto err_ftrace;
1087 }
1088
1089 (*cnt)++;
1090 return ret;
1091
1092err_ftrace:
1093 /*
1094 * At this point, sinec ops is not registered, we should be sefe from
1095 * registering empty filter.
1096 */
1097 ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0);
1098 return ret;
1099}
1100
1101static int arm_kprobe_ftrace(struct kprobe *p)
1102{
1103 bool ipmodify = (p->post_handler != NULL);
1104
1105 return __arm_kprobe_ftrace(p,
1106 ipmodify ? &kprobe_ipmodify_ops : &kprobe_ftrace_ops,
1107 ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);
1108}
1109
1110static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
1111 int *cnt)
1112{
1113 int ret;
1114
1115 lockdep_assert_held(&kprobe_mutex);
1116
1117 if (*cnt == 1) {
1118 ret = unregister_ftrace_function(ops);
1119 if (WARN(ret < 0, "Failed to unregister kprobe-ftrace (error %d)\n", ret))
1120 return ret;
1121 }
1122
1123 (*cnt)--;
1124
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",
1127 p->addr, ret);
1128 return ret;
1129}
1130
1131static int disarm_kprobe_ftrace(struct kprobe *p)
1132{
1133 bool ipmodify = (p->post_handler != NULL);
1134
1135 return __disarm_kprobe_ftrace(p,
1136 ipmodify ? &kprobe_ipmodify_ops : &kprobe_ftrace_ops,
1137 ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);
1138}
1139#else /* !CONFIG_KPROBES_ON_FTRACE */
1140static inline int arm_kprobe_ftrace(struct kprobe *p)
1141{
1142 return -ENODEV;
1143}
1144
1145static inline int disarm_kprobe_ftrace(struct kprobe *p)
1146{
1147 return -ENODEV;
1148}
1149#endif
1150
1151static int prepare_kprobe(struct kprobe *p)
1152{
1153 /* Must ensure p->addr is really on ftrace */
1154 if (kprobe_ftrace(p))
1155 return arch_prepare_kprobe_ftrace(p);
1156
1157 return arch_prepare_kprobe(p);
1158}
1159
1160static int arm_kprobe(struct kprobe *kp)
1161{
1162 if (unlikely(kprobe_ftrace(kp)))
1163 return arm_kprobe_ftrace(kp);
1164
1165 cpus_read_lock();
1166 mutex_lock(&text_mutex);
1167 __arm_kprobe(kp);
1168 mutex_unlock(&text_mutex);
1169 cpus_read_unlock();
1170
1171 return 0;
1172}
1173
1174static int disarm_kprobe(struct kprobe *kp, bool reopt)
1175{
1176 if (unlikely(kprobe_ftrace(kp)))
1177 return disarm_kprobe_ftrace(kp);
1178
1179 cpus_read_lock();
1180 mutex_lock(&text_mutex);
1181 __disarm_kprobe(kp, reopt);
1182 mutex_unlock(&text_mutex);
1183 cpus_read_unlock();
1184
1185 return 0;
1186}
1187
1188/*
1189 * Aggregate handlers for multiple kprobes support - these handlers
1190 * take care of invoking the individual kprobe handlers on p->list
1191 */
1192static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
1193{
1194 struct kprobe *kp;
1195
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))
1200 return 1;
1201 }
1202 reset_kprobe_instance();
1203 }
1204 return 0;
1205}
1206NOKPROBE_SYMBOL(aggr_pre_handler);
1207
1208static void aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
1209 unsigned long flags)
1210{
1211 struct kprobe *kp;
1212
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();
1218 }
1219 }
1220}
1221NOKPROBE_SYMBOL(aggr_post_handler);
1222
1223/* Walks the list and increments 'nmissed' if 'p' has child probes. */
1224void kprobes_inc_nmissed_count(struct kprobe *p)
1225{
1226 struct kprobe *kp;
1227
1228 if (!kprobe_aggrprobe(p)) {
1229 p->nmissed++;
1230 } else {
1231 list_for_each_entry_rcu(kp, &p->list, list)
1232 kp->nmissed++;
1233 }
1234}
1235NOKPROBE_SYMBOL(kprobes_inc_nmissed_count);
1236
1237static struct kprobe kprobe_busy = {
1238 .addr = (void *) get_kprobe,
1239};
1240
1241void kprobe_busy_begin(void)
1242{
1243 struct kprobe_ctlblk *kcb;
1244
1245 preempt_disable();
1246 __this_cpu_write(current_kprobe, &kprobe_busy);
1247 kcb = get_kprobe_ctlblk();
1248 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
1249}
1250
1251void kprobe_busy_end(void)
1252{
1253 __this_cpu_write(current_kprobe, NULL);
1254 preempt_enable();
1255}
1256
1257/* Add the new probe to 'ap->list'. */
1258static int add_new_kprobe(struct kprobe *ap, struct kprobe *p)
1259{
1260 if (p->post_handler)
1261 unoptimize_kprobe(ap, true); /* Fall back to normal kprobe */
1262
1263 list_add_rcu(&p->list, &ap->list);
1264 if (p->post_handler && !ap->post_handler)
1265 ap->post_handler = aggr_post_handler;
1266
1267 return 0;
1268}
1269
1270/*
1271 * Fill in the required fields of the aggregator kprobe. Replace the
1272 * earlier kprobe in the hlist with the aggregator kprobe.
1273 */
1274static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
1275{
1276 /* Copy the insn slot of 'p' to 'ap'. */
1277 copy_kprobe(p, ap);
1278 flush_insn_slot(ap);
1279 ap->addr = p->addr;
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;
1285
1286 INIT_LIST_HEAD(&ap->list);
1287 INIT_HLIST_NODE(&ap->hlist);
1288
1289 list_add_rcu(&p->list, &ap->list);
1290 hlist_replace_rcu(&p->hlist, &ap->hlist);
1291}
1292
1293/*
1294 * This registers the second or subsequent kprobe at the same address.
1295 */
1296static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p)
1297{
1298 int ret = 0;
1299 struct kprobe *ap = orig_p;
1300
1301 cpus_read_lock();
1302
1303 /* For preparing optimization, jump_label_text_reserved() is called */
1304 jump_label_lock();
1305 mutex_lock(&text_mutex);
1306
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);
1310 if (!ap) {
1311 ret = -ENOMEM;
1312 goto out;
1313 }
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);
1318 if (ret)
1319 goto out;
1320 }
1321
1322 if (kprobe_gone(ap)) {
1323 /*
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.
1328 */
1329 ret = arch_prepare_kprobe(ap);
1330 if (ret)
1331 /*
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().
1335 */
1336 goto out;
1337
1338 /* Prepare optimized instructions if possible. */
1339 prepare_optimized_kprobe(ap);
1340
1341 /*
1342 * Clear gone flag to prevent allocating new slot again, and
1343 * set disabled flag because it is not armed yet.
1344 */
1345 ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
1346 | KPROBE_FLAG_DISABLED;
1347 }
1348
1349 /* Copy the insn slot of 'p' to 'ap'. */
1350 copy_kprobe(ap, p);
1351 ret = add_new_kprobe(ap, p);
1352
1353out:
1354 mutex_unlock(&text_mutex);
1355 jump_label_unlock();
1356 cpus_read_unlock();
1357
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);
1363 if (ret) {
1364 ap->flags |= KPROBE_FLAG_DISABLED;
1365 list_del_rcu(&p->list);
1366 synchronize_rcu();
1367 }
1368 }
1369 }
1370 return ret;
1371}
1372
1373bool __weak arch_within_kprobe_blacklist(unsigned long addr)
1374{
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;
1378}
1379
1380static bool __within_kprobe_blacklist(unsigned long addr)
1381{
1382 struct kprobe_blacklist_entry *ent;
1383
1384 if (arch_within_kprobe_blacklist(addr))
1385 return true;
1386 /*
1387 * If 'kprobe_blacklist' is defined, check the address and
1388 * reject any probe registration in the prohibited area.
1389 */
1390 list_for_each_entry(ent, &kprobe_blacklist, list) {
1391 if (addr >= ent->start_addr && addr < ent->end_addr)
1392 return true;
1393 }
1394 return false;
1395}
1396
1397bool within_kprobe_blacklist(unsigned long addr)
1398{
1399 char symname[KSYM_NAME_LEN], *p;
1400
1401 if (__within_kprobe_blacklist(addr))
1402 return true;
1403
1404 /* Check if the address is on a suffixed-symbol */
1405 if (!lookup_symbol_name(addr, symname)) {
1406 p = strchr(symname, '.');
1407 if (!p)
1408 return false;
1409 *p = '\0';
1410 addr = (unsigned long)kprobe_lookup_name(symname, 0);
1411 if (addr)
1412 return __within_kprobe_blacklist(addr);
1413 }
1414 return false;
1415}
1416
1417/*
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
1422 *
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
1426 * symbol.
1427 *
1428 * Specifically, for things like IBT/BTI, skip the resp. ENDBR/BTI.C
1429 * instruction at +0.
1430 */
1431kprobe_opcode_t *__weak arch_adjust_kprobe_addr(unsigned long addr,
1432 unsigned long offset,
1433 bool *on_func_entry)
1434{
1435 *on_func_entry = !offset;
1436 return (kprobe_opcode_t *)(addr + offset);
1437}
1438
1439/*
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.
1444 */
1445static kprobe_opcode_t *
1446_kprobe_addr(kprobe_opcode_t *addr, const char *symbol_name,
1447 unsigned long offset, bool *on_func_entry)
1448{
1449 if ((symbol_name && addr) || (!symbol_name && !addr))
1450 goto invalid;
1451
1452 if (symbol_name) {
1453 /*
1454 * Input: @sym + @offset
1455 * Output: @addr + @offset
1456 *
1457 * NOTE: kprobe_lookup_name() does *NOT* fold the offset
1458 * argument into it's output!
1459 */
1460 addr = kprobe_lookup_name(symbol_name, offset);
1461 if (!addr)
1462 return ERR_PTR(-ENOENT);
1463 }
1464
1465 /*
1466 * So here we have @addr + @offset, displace it into a new
1467 * @addr' + @offset' where @addr' is the symbol start address.
1468 */
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;
1473
1474 /*
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.
1478 */
1479 addr = arch_adjust_kprobe_addr((unsigned long)addr, offset, on_func_entry);
1480 if (addr)
1481 return addr;
1482
1483invalid:
1484 return ERR_PTR(-EINVAL);
1485}
1486
1487static kprobe_opcode_t *kprobe_addr(struct kprobe *p)
1488{
1489 bool on_func_entry;
1490 return _kprobe_addr(p->addr, p->symbol_name, p->offset, &on_func_entry);
1491}
1492
1493/*
1494 * Check the 'p' is valid and return the aggregator kprobe
1495 * at the same address.
1496 */
1497static struct kprobe *__get_valid_kprobe(struct kprobe *p)
1498{
1499 struct kprobe *ap, *list_p;
1500
1501 lockdep_assert_held(&kprobe_mutex);
1502
1503 ap = get_kprobe(p->addr);
1504 if (unlikely(!ap))
1505 return NULL;
1506
1507 if (p != ap) {
1508 list_for_each_entry(list_p, &ap->list, list)
1509 if (list_p == p)
1510 /* kprobe p is a valid probe */
1511 goto valid;
1512 return NULL;
1513 }
1514valid:
1515 return ap;
1516}
1517
1518/*
1519 * Warn and return error if the kprobe is being re-registered since
1520 * there must be a software bug.
1521 */
1522static inline int warn_kprobe_rereg(struct kprobe *p)
1523{
1524 int ret = 0;
1525
1526 mutex_lock(&kprobe_mutex);
1527 if (WARN_ON_ONCE(__get_valid_kprobe(p)))
1528 ret = -EINVAL;
1529 mutex_unlock(&kprobe_mutex);
1530
1531 return ret;
1532}
1533
1534static int check_ftrace_location(struct kprobe *p)
1535{
1536 unsigned long addr = (unsigned long)p->addr;
1537
1538 if (ftrace_location(addr) == addr) {
1539#ifdef CONFIG_KPROBES_ON_FTRACE
1540 p->flags |= KPROBE_FLAG_FTRACE;
1541#else /* !CONFIG_KPROBES_ON_FTRACE */
1542 return -EINVAL;
1543#endif
1544 }
1545 return 0;
1546}
1547
1548static bool is_cfi_preamble_symbol(unsigned long addr)
1549{
1550 char symbuf[KSYM_NAME_LEN];
1551
1552 if (lookup_symbol_name(addr, symbuf))
1553 return false;
1554
1555 return str_has_prefix("__cfi_", symbuf) ||
1556 str_has_prefix("__pfx_", symbuf);
1557}
1558
1559static int check_kprobe_address_safe(struct kprobe *p,
1560 struct module **probed_mod)
1561{
1562 int ret;
1563
1564 ret = check_ftrace_location(p);
1565 if (ret)
1566 return ret;
1567 jump_label_lock();
1568 preempt_disable();
1569
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)) {
1579 ret = -EINVAL;
1580 goto out;
1581 }
1582
1583 /* Check if 'p' is probing a module. */
1584 *probed_mod = __module_text_address((unsigned long) p->addr);
1585 if (*probed_mod) {
1586 /*
1587 * We must hold a refcount of the probed module while updating
1588 * its code to prohibit unexpected unloading.
1589 */
1590 if (unlikely(!try_module_get(*probed_mod))) {
1591 ret = -ENOENT;
1592 goto out;
1593 }
1594
1595 /*
1596 * If the module freed '.init.text', we couldn't insert
1597 * kprobes in there.
1598 */
1599 if (within_module_init((unsigned long)p->addr, *probed_mod) &&
1600 (*probed_mod)->state != MODULE_STATE_COMING) {
1601 module_put(*probed_mod);
1602 *probed_mod = NULL;
1603 ret = -ENOENT;
1604 }
1605 }
1606out:
1607 preempt_enable();
1608 jump_label_unlock();
1609
1610 return ret;
1611}
1612
1613int register_kprobe(struct kprobe *p)
1614{
1615 int ret;
1616 struct kprobe *old_p;
1617 struct module *probed_mod;
1618 kprobe_opcode_t *addr;
1619 bool on_func_entry;
1620
1621 /* Adjust probe address from symbol */
1622 addr = _kprobe_addr(p->addr, p->symbol_name, p->offset, &on_func_entry);
1623 if (IS_ERR(addr))
1624 return PTR_ERR(addr);
1625 p->addr = addr;
1626
1627 ret = warn_kprobe_rereg(p);
1628 if (ret)
1629 return ret;
1630
1631 /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
1632 p->flags &= KPROBE_FLAG_DISABLED;
1633 p->nmissed = 0;
1634 INIT_LIST_HEAD(&p->list);
1635
1636 ret = check_kprobe_address_safe(p, &probed_mod);
1637 if (ret)
1638 return ret;
1639
1640 mutex_lock(&kprobe_mutex);
1641
1642 if (on_func_entry)
1643 p->flags |= KPROBE_FLAG_ON_FUNC_ENTRY;
1644
1645 old_p = get_kprobe(p->addr);
1646 if (old_p) {
1647 /* Since this may unoptimize 'old_p', locking 'text_mutex'. */
1648 ret = register_aggr_kprobe(old_p, p);
1649 goto out;
1650 }
1651
1652 cpus_read_lock();
1653 /* Prevent text modification */
1654 mutex_lock(&text_mutex);
1655 ret = prepare_kprobe(p);
1656 mutex_unlock(&text_mutex);
1657 cpus_read_unlock();
1658 if (ret)
1659 goto out;
1660
1661 INIT_HLIST_NODE(&p->hlist);
1662 hlist_add_head_rcu(&p->hlist,
1663 &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
1664
1665 if (!kprobes_all_disarmed && !kprobe_disabled(p)) {
1666 ret = arm_kprobe(p);
1667 if (ret) {
1668 hlist_del_rcu(&p->hlist);
1669 synchronize_rcu();
1670 goto out;
1671 }
1672 }
1673
1674 /* Try to optimize kprobe */
1675 try_to_optimize_kprobe(p);
1676out:
1677 mutex_unlock(&kprobe_mutex);
1678
1679 if (probed_mod)
1680 module_put(probed_mod);
1681
1682 return ret;
1683}
1684EXPORT_SYMBOL_GPL(register_kprobe);
1685
1686/* Check if all probes on the 'ap' are disabled. */
1687static bool aggr_kprobe_disabled(struct kprobe *ap)
1688{
1689 struct kprobe *kp;
1690
1691 lockdep_assert_held(&kprobe_mutex);
1692
1693 list_for_each_entry(kp, &ap->list, list)
1694 if (!kprobe_disabled(kp))
1695 /*
1696 * Since there is an active probe on the list,
1697 * we can't disable this 'ap'.
1698 */
1699 return false;
1700
1701 return true;
1702}
1703
1704static struct kprobe *__disable_kprobe(struct kprobe *p)
1705{
1706 struct kprobe *orig_p;
1707 int ret;
1708
1709 lockdep_assert_held(&kprobe_mutex);
1710
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);
1715
1716 if (!kprobe_disabled(p)) {
1717 /* Disable probe if it is a child probe */
1718 if (p != orig_p)
1719 p->flags |= KPROBE_FLAG_DISABLED;
1720
1721 /* Try to disarm and disable this/parent probe */
1722 if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
1723 /*
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.
1728 */
1729 if (!kprobes_all_disarmed && !kprobe_disabled(orig_p)) {
1730 ret = disarm_kprobe(orig_p, true);
1731 if (ret) {
1732 p->flags &= ~KPROBE_FLAG_DISABLED;
1733 return ERR_PTR(ret);
1734 }
1735 }
1736 orig_p->flags |= KPROBE_FLAG_DISABLED;
1737 }
1738 }
1739
1740 return orig_p;
1741}
1742
1743/*
1744 * Unregister a kprobe without a scheduler synchronization.
1745 */
1746static int __unregister_kprobe_top(struct kprobe *p)
1747{
1748 struct kprobe *ap, *list_p;
1749
1750 /* Disable kprobe. This will disarm it if needed. */
1751 ap = __disable_kprobe(p);
1752 if (IS_ERR(ap))
1753 return PTR_ERR(ap);
1754
1755 if (ap == p)
1756 /*
1757 * This probe is an independent(and non-optimized) kprobe
1758 * (not an aggrprobe). Remove from the hash list.
1759 */
1760 goto disarmed;
1761
1762 /* Following process expects this probe is an aggrprobe */
1763 WARN_ON(!kprobe_aggrprobe(ap));
1764
1765 if (list_is_singular(&ap->list) && kprobe_disarmed(ap))
1766 /*
1767 * !disarmed could be happen if the probe is under delayed
1768 * unoptimizing.
1769 */
1770 goto disarmed;
1771 else {
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))
1776 goto noclean;
1777 }
1778 /*
1779 * For the kprobe-on-ftrace case, we keep the
1780 * post_handler setting to identify this aggrprobe
1781 * armed with kprobe_ipmodify_ops.
1782 */
1783 if (!kprobe_ftrace(ap))
1784 ap->post_handler = NULL;
1785 }
1786noclean:
1787 /*
1788 * Remove from the aggrprobe: this path will do nothing in
1789 * __unregister_kprobe_bottom().
1790 */
1791 list_del_rcu(&p->list);
1792 if (!kprobe_disabled(ap) && !kprobes_all_disarmed)
1793 /*
1794 * Try to optimize this probe again, because post
1795 * handler may have been changed.
1796 */
1797 optimize_kprobe(ap);
1798 }
1799 return 0;
1800
1801disarmed:
1802 hlist_del_rcu(&ap->hlist);
1803 return 0;
1804}
1805
1806static void __unregister_kprobe_bottom(struct kprobe *p)
1807{
1808 struct kprobe *ap;
1809
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);
1816 list_del(&p->list);
1817 free_aggr_kprobe(ap);
1818 }
1819 /* Otherwise, do nothing. */
1820}
1821
1822int register_kprobes(struct kprobe **kps, int num)
1823{
1824 int i, ret = 0;
1825
1826 if (num <= 0)
1827 return -EINVAL;
1828 for (i = 0; i < num; i++) {
1829 ret = register_kprobe(kps[i]);
1830 if (ret < 0) {
1831 if (i > 0)
1832 unregister_kprobes(kps, i);
1833 break;
1834 }
1835 }
1836 return ret;
1837}
1838EXPORT_SYMBOL_GPL(register_kprobes);
1839
1840void unregister_kprobe(struct kprobe *p)
1841{
1842 unregister_kprobes(&p, 1);
1843}
1844EXPORT_SYMBOL_GPL(unregister_kprobe);
1845
1846void unregister_kprobes(struct kprobe **kps, int num)
1847{
1848 int i;
1849
1850 if (num <= 0)
1851 return;
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);
1857
1858 synchronize_rcu();
1859 for (i = 0; i < num; i++)
1860 if (kps[i]->addr)
1861 __unregister_kprobe_bottom(kps[i]);
1862}
1863EXPORT_SYMBOL_GPL(unregister_kprobes);
1864
1865int __weak kprobe_exceptions_notify(struct notifier_block *self,
1866 unsigned long val, void *data)
1867{
1868 return NOTIFY_DONE;
1869}
1870NOKPROBE_SYMBOL(kprobe_exceptions_notify);
1871
1872static struct notifier_block kprobe_exceptions_nb = {
1873 .notifier_call = kprobe_exceptions_notify,
1874 .priority = 0x7fffffff /* we need to be notified first */
1875};
1876
1877#ifdef CONFIG_KRETPROBES
1878
1879#if !defined(CONFIG_KRETPROBE_ON_RETHOOK)
1880
1881/* callbacks for objpool of kretprobe instances */
1882static int kretprobe_init_inst(void *nod, void *context)
1883{
1884 struct kretprobe_instance *ri = nod;
1885
1886 ri->rph = context;
1887 return 0;
1888}
1889static int kretprobe_fini_pool(struct objpool_head *head, void *context)
1890{
1891 kfree(context);
1892 return 0;
1893}
1894
1895static void free_rp_inst_rcu(struct rcu_head *head)
1896{
1897 struct kretprobe_instance *ri = container_of(head, struct kretprobe_instance, rcu);
1898 struct kretprobe_holder *rph = ri->rph;
1899
1900 objpool_drop(ri, &rph->pool);
1901}
1902NOKPROBE_SYMBOL(free_rp_inst_rcu);
1903
1904static void recycle_rp_inst(struct kretprobe_instance *ri)
1905{
1906 struct kretprobe *rp = get_kretprobe(ri);
1907
1908 if (likely(rp))
1909 objpool_push(ri, &rp->rph->pool);
1910 else
1911 call_rcu(&ri->rcu, free_rp_inst_rcu);
1912}
1913NOKPROBE_SYMBOL(recycle_rp_inst);
1914
1915/*
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.
1920 */
1921void kprobe_flush_task(struct task_struct *tk)
1922{
1923 struct kretprobe_instance *ri;
1924 struct llist_node *node;
1925
1926 /* Early boot, not yet initialized. */
1927 if (unlikely(!kprobes_initialized))
1928 return;
1929
1930 kprobe_busy_begin();
1931
1932 node = __llist_del_all(&tk->kretprobe_instances);
1933 while (node) {
1934 ri = container_of(node, struct kretprobe_instance, llist);
1935 node = node->next;
1936
1937 recycle_rp_inst(ri);
1938 }
1939
1940 kprobe_busy_end();
1941}
1942NOKPROBE_SYMBOL(kprobe_flush_task);
1943
1944static inline void free_rp_inst(struct kretprobe *rp)
1945{
1946 struct kretprobe_holder *rph = rp->rph;
1947
1948 if (!rph)
1949 return;
1950 rp->rph = NULL;
1951 objpool_fini(&rph->pool);
1952}
1953
1954/* This assumes the 'tsk' is the current task or the is not running. */
1955static kprobe_opcode_t *__kretprobe_find_ret_addr(struct task_struct *tsk,
1956 struct llist_node **cur)
1957{
1958 struct kretprobe_instance *ri = NULL;
1959 struct llist_node *node = *cur;
1960
1961 if (!node)
1962 node = tsk->kretprobe_instances.first;
1963 else
1964 node = node->next;
1965
1966 while (node) {
1967 ri = container_of(node, struct kretprobe_instance, llist);
1968 if (ri->ret_addr != kretprobe_trampoline_addr()) {
1969 *cur = node;
1970 return ri->ret_addr;
1971 }
1972 node = node->next;
1973 }
1974 return NULL;
1975}
1976NOKPROBE_SYMBOL(__kretprobe_find_ret_addr);
1977
1978/**
1979 * kretprobe_find_ret_addr -- Find correct return address modified by kretprobe
1980 * @tsk: Target task
1981 * @fp: A frame pointer
1982 * @cur: a storage of the loop cursor llist_node pointer for next call
1983 *
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.
1992 */
1993unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
1994 struct llist_node **cur)
1995{
1996 struct kretprobe_instance *ri;
1997 kprobe_opcode_t *ret;
1998
1999 if (WARN_ON_ONCE(!cur))
2000 return 0;
2001
2002 do {
2003 ret = __kretprobe_find_ret_addr(tsk, cur);
2004 if (!ret)
2005 break;
2006 ri = container_of(*cur, struct kretprobe_instance, llist);
2007 } while (ri->fp != fp);
2008
2009 return (unsigned long)ret;
2010}
2011NOKPROBE_SYMBOL(kretprobe_find_ret_addr);
2012
2013void __weak arch_kretprobe_fixup_return(struct pt_regs *regs,
2014 kprobe_opcode_t *correct_ret_addr)
2015{
2016 /*
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.
2019 */
2020}
2021
2022unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
2023 void *frame_pointer)
2024{
2025 struct kretprobe_instance *ri = NULL;
2026 struct llist_node *first, *node = NULL;
2027 kprobe_opcode_t *correct_ret_addr;
2028 struct kretprobe *rp;
2029
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");
2034 BUG_ON(1);
2035 }
2036
2037 /*
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.
2041 */
2042 instruction_pointer_set(regs, (unsigned long)correct_ret_addr);
2043
2044 /* Run the user handler of the nodes. */
2045 first = current->kretprobe_instances.first;
2046 while (first) {
2047 ri = container_of(first, struct kretprobe_instance, llist);
2048
2049 if (WARN_ON_ONCE(ri->fp != frame_pointer))
2050 break;
2051
2052 rp = get_kretprobe(ri);
2053 if (rp && rp->handler) {
2054 struct kprobe *prev = kprobe_running();
2055
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);
2060 }
2061 if (first == node)
2062 break;
2063
2064 first = first->next;
2065 }
2066
2067 arch_kretprobe_fixup_return(regs, correct_ret_addr);
2068
2069 /* Unlink all nodes for this frame. */
2070 first = current->kretprobe_instances.first;
2071 current->kretprobe_instances.first = node->next;
2072 node->next = NULL;
2073
2074 /* Recycle free instances. */
2075 while (first) {
2076 ri = container_of(first, struct kretprobe_instance, llist);
2077 first = first->next;
2078
2079 recycle_rp_inst(ri);
2080 }
2081
2082 return (unsigned long)correct_ret_addr;
2083}
2084NOKPROBE_SYMBOL(__kretprobe_trampoline_handler)
2085
2086/*
2087 * This kprobe pre_handler is registered with every kretprobe. When probe
2088 * hits it will set up the return probe.
2089 */
2090static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
2091{
2092 struct kretprobe *rp = container_of(p, struct kretprobe, kp);
2093 struct kretprobe_holder *rph = rp->rph;
2094 struct kretprobe_instance *ri;
2095
2096 ri = objpool_pop(&rph->pool);
2097 if (!ri) {
2098 rp->nmissed++;
2099 return 0;
2100 }
2101
2102 if (rp->entry_handler && rp->entry_handler(ri, regs)) {
2103 objpool_push(ri, &rph->pool);
2104 return 0;
2105 }
2106
2107 arch_prepare_kretprobe(ri, regs);
2108
2109 __llist_add(&ri->llist, ¤t->kretprobe_instances);
2110
2111 return 0;
2112}
2113NOKPROBE_SYMBOL(pre_handler_kretprobe);
2114#else /* CONFIG_KRETPROBE_ON_RETHOOK */
2115/*
2116 * This kprobe pre_handler is registered with every kretprobe. When probe
2117 * hits it will set up the return probe.
2118 */
2119static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
2120{
2121 struct kretprobe *rp = container_of(p, struct kretprobe, kp);
2122 struct kretprobe_instance *ri;
2123 struct rethook_node *rhn;
2124
2125 rhn = rethook_try_get(rp->rh);
2126 if (!rhn) {
2127 rp->nmissed++;
2128 return 0;
2129 }
2130
2131 ri = container_of(rhn, struct kretprobe_instance, node);
2132
2133 if (rp->entry_handler && rp->entry_handler(ri, regs))
2134 rethook_recycle(rhn);
2135 else
2136 rethook_hook(rhn, regs, kprobe_ftrace(p));
2137
2138 return 0;
2139}
2140NOKPROBE_SYMBOL(pre_handler_kretprobe);
2141
2142static void kretprobe_rethook_handler(struct rethook_node *rh, void *data,
2143 unsigned long ret_addr,
2144 struct pt_regs *regs)
2145{
2146 struct kretprobe *rp = (struct kretprobe *)data;
2147 struct kretprobe_instance *ri;
2148 struct kprobe_ctlblk *kcb;
2149
2150 /* The data must NOT be null. This means rethook data structure is broken. */
2151 if (WARN_ON_ONCE(!data) || !rp->handler)
2152 return;
2153
2154 __this_cpu_write(current_kprobe, &rp->kp);
2155 kcb = get_kprobe_ctlblk();
2156 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
2157
2158 ri = container_of(rh, struct kretprobe_instance, node);
2159 rp->handler(ri, regs);
2160
2161 __this_cpu_write(current_kprobe, NULL);
2162}
2163NOKPROBE_SYMBOL(kretprobe_rethook_handler);
2164
2165#endif /* !CONFIG_KRETPROBE_ON_RETHOOK */
2166
2167/**
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
2172 *
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
2178 * returns -EINVAL.
2179 */
2180int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset)
2181{
2182 bool on_func_entry;
2183 kprobe_opcode_t *kp_addr = _kprobe_addr(addr, sym, offset, &on_func_entry);
2184
2185 if (IS_ERR(kp_addr))
2186 return PTR_ERR(kp_addr);
2187
2188 if (!on_func_entry)
2189 return -EINVAL;
2190
2191 return 0;
2192}
2193
2194int register_kretprobe(struct kretprobe *rp)
2195{
2196 int ret;
2197 int i;
2198 void *addr;
2199
2200 ret = kprobe_on_func_entry(rp->kp.addr, rp->kp.symbol_name, rp->kp.offset);
2201 if (ret)
2202 return ret;
2203
2204 /* If only 'rp->kp.addr' is specified, check reregistering kprobes */
2205 if (rp->kp.addr && warn_kprobe_rereg(&rp->kp))
2206 return -EINVAL;
2207
2208 if (kretprobe_blacklist_size) {
2209 addr = kprobe_addr(&rp->kp);
2210 if (IS_ERR(addr))
2211 return PTR_ERR(addr);
2212
2213 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
2214 if (kretprobe_blacklist[i].addr == addr)
2215 return -EINVAL;
2216 }
2217 }
2218
2219 if (rp->data_size > KRETPROBE_MAX_DATA_SIZE)
2220 return -E2BIG;
2221
2222 rp->kp.pre_handler = pre_handler_kretprobe;
2223 rp->kp.post_handler = NULL;
2224
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());
2228
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);
2233 if (IS_ERR(rp->rh))
2234 return PTR_ERR(rp->rh);
2235
2236 rp->nmissed = 0;
2237 /* Establish function entry probe point */
2238 ret = register_kprobe(&rp->kp);
2239 if (ret != 0) {
2240 rethook_free(rp->rh);
2241 rp->rh = NULL;
2242 }
2243#else /* !CONFIG_KRETPROBE_ON_RETHOOK */
2244 rp->rph = kzalloc(sizeof(struct kretprobe_holder), GFP_KERNEL);
2245 if (!rp->rph)
2246 return -ENOMEM;
2247
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)) {
2251 kfree(rp->rph);
2252 rp->rph = NULL;
2253 return -ENOMEM;
2254 }
2255 rcu_assign_pointer(rp->rph->rp, rp);
2256 rp->nmissed = 0;
2257 /* Establish function entry probe point */
2258 ret = register_kprobe(&rp->kp);
2259 if (ret != 0)
2260 free_rp_inst(rp);
2261#endif
2262 return ret;
2263}
2264EXPORT_SYMBOL_GPL(register_kretprobe);
2265
2266int register_kretprobes(struct kretprobe **rps, int num)
2267{
2268 int ret = 0, i;
2269
2270 if (num <= 0)
2271 return -EINVAL;
2272 for (i = 0; i < num; i++) {
2273 ret = register_kretprobe(rps[i]);
2274 if (ret < 0) {
2275 if (i > 0)
2276 unregister_kretprobes(rps, i);
2277 break;
2278 }
2279 }
2280 return ret;
2281}
2282EXPORT_SYMBOL_GPL(register_kretprobes);
2283
2284void unregister_kretprobe(struct kretprobe *rp)
2285{
2286 unregister_kretprobes(&rp, 1);
2287}
2288EXPORT_SYMBOL_GPL(unregister_kretprobe);
2289
2290void unregister_kretprobes(struct kretprobe **rps, int num)
2291{
2292 int i;
2293
2294 if (num <= 0)
2295 return;
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);
2302#else
2303 rcu_assign_pointer(rps[i]->rph->rp, NULL);
2304#endif
2305 }
2306 mutex_unlock(&kprobe_mutex);
2307
2308 synchronize_rcu();
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]);
2314#endif
2315 }
2316 }
2317}
2318EXPORT_SYMBOL_GPL(unregister_kretprobes);
2319
2320#else /* CONFIG_KRETPROBES */
2321int register_kretprobe(struct kretprobe *rp)
2322{
2323 return -EOPNOTSUPP;
2324}
2325EXPORT_SYMBOL_GPL(register_kretprobe);
2326
2327int register_kretprobes(struct kretprobe **rps, int num)
2328{
2329 return -EOPNOTSUPP;
2330}
2331EXPORT_SYMBOL_GPL(register_kretprobes);
2332
2333void unregister_kretprobe(struct kretprobe *rp)
2334{
2335}
2336EXPORT_SYMBOL_GPL(unregister_kretprobe);
2337
2338void unregister_kretprobes(struct kretprobe **rps, int num)
2339{
2340}
2341EXPORT_SYMBOL_GPL(unregister_kretprobes);
2342
2343static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
2344{
2345 return 0;
2346}
2347NOKPROBE_SYMBOL(pre_handler_kretprobe);
2348
2349#endif /* CONFIG_KRETPROBES */
2350
2351/* Set the kprobe gone and remove its instruction buffer. */
2352static void kill_kprobe(struct kprobe *p)
2353{
2354 struct kprobe *kp;
2355
2356 lockdep_assert_held(&kprobe_mutex);
2357
2358 /*
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.
2362 */
2363 if (kprobe_ftrace(p) && !kprobe_disabled(p) && !kprobes_all_disarmed)
2364 disarm_kprobe_ftrace(p);
2365
2366 p->flags |= KPROBE_FLAG_GONE;
2367 if (kprobe_aggrprobe(p)) {
2368 /*
2369 * If this is an aggr_kprobe, we have to list all the
2370 * chained probes and mark them GONE.
2371 */
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);
2376 }
2377 /*
2378 * Here, we can remove insn_slot safely, because no thread calls
2379 * the original probed function (which will be freed soon) any more.
2380 */
2381 arch_remove_kprobe(p);
2382}
2383
2384/* Disable one kprobe */
2385int disable_kprobe(struct kprobe *kp)
2386{
2387 int ret = 0;
2388 struct kprobe *p;
2389
2390 mutex_lock(&kprobe_mutex);
2391
2392 /* Disable this kprobe */
2393 p = __disable_kprobe(kp);
2394 if (IS_ERR(p))
2395 ret = PTR_ERR(p);
2396
2397 mutex_unlock(&kprobe_mutex);
2398 return ret;
2399}
2400EXPORT_SYMBOL_GPL(disable_kprobe);
2401
2402/* Enable one kprobe */
2403int enable_kprobe(struct kprobe *kp)
2404{
2405 int ret = 0;
2406 struct kprobe *p;
2407
2408 mutex_lock(&kprobe_mutex);
2409
2410 /* Check whether specified probe is valid. */
2411 p = __get_valid_kprobe(kp);
2412 if (unlikely(p == NULL)) {
2413 ret = -EINVAL;
2414 goto out;
2415 }
2416
2417 if (kprobe_gone(kp)) {
2418 /* This kprobe has gone, we couldn't enable it. */
2419 ret = -EINVAL;
2420 goto out;
2421 }
2422
2423 if (p != kp)
2424 kp->flags &= ~KPROBE_FLAG_DISABLED;
2425
2426 if (!kprobes_all_disarmed && kprobe_disabled(p)) {
2427 p->flags &= ~KPROBE_FLAG_DISABLED;
2428 ret = arm_kprobe(p);
2429 if (ret) {
2430 p->flags |= KPROBE_FLAG_DISABLED;
2431 if (p != kp)
2432 kp->flags |= KPROBE_FLAG_DISABLED;
2433 }
2434 }
2435out:
2436 mutex_unlock(&kprobe_mutex);
2437 return ret;
2438}
2439EXPORT_SYMBOL_GPL(enable_kprobe);
2440
2441/* Caller must NOT call this in usual path. This is only for critical case */
2442void dump_kprobe(struct kprobe *kp)
2443{
2444 pr_err("Dump kprobe:\n.symbol_name = %s, .offset = %x, .addr = %pS\n",
2445 kp->symbol_name, kp->offset, kp->addr);
2446}
2447NOKPROBE_SYMBOL(dump_kprobe);
2448
2449int kprobe_add_ksym_blacklist(unsigned long entry)
2450{
2451 struct kprobe_blacklist_entry *ent;
2452 unsigned long offset = 0, size = 0;
2453
2454 if (!kernel_text_address(entry) ||
2455 !kallsyms_lookup_size_offset(entry, &size, &offset))
2456 return -EINVAL;
2457
2458 ent = kmalloc(sizeof(*ent), GFP_KERNEL);
2459 if (!ent)
2460 return -ENOMEM;
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);
2465
2466 return (int)size;
2467}
2468
2469/* Add all symbols in given area into kprobe blacklist */
2470int kprobe_add_area_blacklist(unsigned long start, unsigned long end)
2471{
2472 unsigned long entry;
2473 int ret = 0;
2474
2475 for (entry = start; entry < end; entry += ret) {
2476 ret = kprobe_add_ksym_blacklist(entry);
2477 if (ret < 0)
2478 return ret;
2479 if (ret == 0) /* In case of alias symbol */
2480 ret = 1;
2481 }
2482 return 0;
2483}
2484
2485/* Remove all symbols in given area from kprobe blacklist */
2486static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end)
2487{
2488 struct kprobe_blacklist_entry *ent, *n;
2489
2490 list_for_each_entry_safe(ent, n, &kprobe_blacklist, list) {
2491 if (ent->start_addr < start || ent->start_addr >= end)
2492 continue;
2493 list_del(&ent->list);
2494 kfree(ent);
2495 }
2496}
2497
2498static void kprobe_remove_ksym_blacklist(unsigned long entry)
2499{
2500 kprobe_remove_area_blacklist(entry, entry + 1);
2501}
2502
2503int __weak arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value,
2504 char *type, char *sym)
2505{
2506 return -ERANGE;
2507}
2508
2509int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
2510 char *sym)
2511{
2512#ifdef __ARCH_WANT_KPROBES_INSN_SLOT
2513 if (!kprobe_cache_get_kallsym(&kprobe_insn_slots, &symnum, value, type, sym))
2514 return 0;
2515#ifdef CONFIG_OPTPROBES
2516 if (!kprobe_cache_get_kallsym(&kprobe_optinsn_slots, &symnum, value, type, sym))
2517 return 0;
2518#endif
2519#endif
2520 if (!arch_kprobe_get_kallsym(&symnum, value, type, sym))
2521 return 0;
2522 return -ERANGE;
2523}
2524
2525int __init __weak arch_populate_kprobe_blacklist(void)
2526{
2527 return 0;
2528}
2529
2530/*
2531 * Lookup and populate the kprobe_blacklist.
2532 *
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
2536 * of a function.
2537 */
2538static int __init populate_kprobe_blacklist(unsigned long *start,
2539 unsigned long *end)
2540{
2541 unsigned long entry;
2542 unsigned long *iter;
2543 int ret;
2544
2545 for (iter = start; iter < end; iter++) {
2546 entry = (unsigned long)dereference_symbol_descriptor((void *)*iter);
2547 ret = kprobe_add_ksym_blacklist(entry);
2548 if (ret == -EINVAL)
2549 continue;
2550 if (ret < 0)
2551 return ret;
2552 }
2553
2554 /* Symbols in '__kprobes_text' are blacklisted */
2555 ret = kprobe_add_area_blacklist((unsigned long)__kprobes_text_start,
2556 (unsigned long)__kprobes_text_end);
2557 if (ret)
2558 return ret;
2559
2560 /* Symbols in 'noinstr' section are blacklisted */
2561 ret = kprobe_add_area_blacklist((unsigned long)__noinstr_text_start,
2562 (unsigned long)__noinstr_text_end);
2563
2564 return ret ? : arch_populate_kprobe_blacklist();
2565}
2566
2567static void add_module_kprobe_blacklist(struct module *mod)
2568{
2569 unsigned long start, end;
2570 int i;
2571
2572 if (mod->kprobe_blacklist) {
2573 for (i = 0; i < mod->num_kprobe_blacklist; i++)
2574 kprobe_add_ksym_blacklist(mod->kprobe_blacklist[i]);
2575 }
2576
2577 start = (unsigned long)mod->kprobes_text_start;
2578 if (start) {
2579 end = start + mod->kprobes_text_size;
2580 kprobe_add_area_blacklist(start, end);
2581 }
2582
2583 start = (unsigned long)mod->noinstr_text_start;
2584 if (start) {
2585 end = start + mod->noinstr_text_size;
2586 kprobe_add_area_blacklist(start, end);
2587 }
2588}
2589
2590static void remove_module_kprobe_blacklist(struct module *mod)
2591{
2592 unsigned long start, end;
2593 int i;
2594
2595 if (mod->kprobe_blacklist) {
2596 for (i = 0; i < mod->num_kprobe_blacklist; i++)
2597 kprobe_remove_ksym_blacklist(mod->kprobe_blacklist[i]);
2598 }
2599
2600 start = (unsigned long)mod->kprobes_text_start;
2601 if (start) {
2602 end = start + mod->kprobes_text_size;
2603 kprobe_remove_area_blacklist(start, end);
2604 }
2605
2606 start = (unsigned long)mod->noinstr_text_start;
2607 if (start) {
2608 end = start + mod->noinstr_text_size;
2609 kprobe_remove_area_blacklist(start, end);
2610 }
2611}
2612
2613/* Module notifier call back, checking kprobes on the module */
2614static int kprobes_module_callback(struct notifier_block *nb,
2615 unsigned long val, void *data)
2616{
2617 struct module *mod = data;
2618 struct hlist_head *head;
2619 struct kprobe *p;
2620 unsigned int i;
2621 int checkcore = (val == MODULE_STATE_GOING);
2622
2623 if (val == MODULE_STATE_COMING) {
2624 mutex_lock(&kprobe_mutex);
2625 add_module_kprobe_blacklist(mod);
2626 mutex_unlock(&kprobe_mutex);
2627 }
2628 if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
2629 return NOTIFY_DONE;
2630
2631 /*
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.
2636 */
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) ||
2642 (checkcore &&
2643 within_module_core((unsigned long)p->addr, mod))) {
2644 /*
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.
2648 *
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.
2654 */
2655 kill_kprobe(p);
2656 }
2657 }
2658 if (val == MODULE_STATE_GOING)
2659 remove_module_kprobe_blacklist(mod);
2660 mutex_unlock(&kprobe_mutex);
2661 return NOTIFY_DONE;
2662}
2663
2664static struct notifier_block kprobe_module_nb = {
2665 .notifier_call = kprobes_module_callback,
2666 .priority = 0
2667};
2668
2669void kprobe_free_init_mem(void)
2670{
2671 void *start = (void *)(&__init_begin);
2672 void *end = (void *)(&__init_end);
2673 struct hlist_head *head;
2674 struct kprobe *p;
2675 int i;
2676
2677 mutex_lock(&kprobe_mutex);
2678
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)
2684 kill_kprobe(p);
2685 }
2686 }
2687
2688 mutex_unlock(&kprobe_mutex);
2689}
2690
2691static int __init init_kprobes(void)
2692{
2693 int i, err;
2694
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]);
2699
2700 err = populate_kprobe_blacklist(__start_kprobe_blacklist,
2701 __stop_kprobe_blacklist);
2702 if (err)
2703 pr_err("Failed to populate blacklist (error %d), kprobes not restricted, be careful using them!\n", err);
2704
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);
2713 }
2714 }
2715
2716 /* By default, kprobes are armed */
2717 kprobes_all_disarmed = false;
2718
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;
2722#endif
2723
2724 err = arch_init_kprobes();
2725 if (!err)
2726 err = register_die_notifier(&kprobe_exceptions_nb);
2727 if (!err)
2728 err = register_module_notifier(&kprobe_module_nb);
2729
2730 kprobes_initialized = (err == 0);
2731 kprobe_sysctls_init();
2732 return err;
2733}
2734early_initcall(init_kprobes);
2735
2736#if defined(CONFIG_OPTPROBES)
2737static int __init init_optprobes(void)
2738{
2739 /*
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.
2743 */
2744 optimize_all_kprobes();
2745
2746 return 0;
2747}
2748subsys_initcall(init_optprobes);
2749#endif
2750
2751#ifdef CONFIG_DEBUG_FS
2752static void report_probe(struct seq_file *pi, struct kprobe *p,
2753 const char *sym, int offset, char *modname, struct kprobe *pp)
2754{
2755 char *kprobe_type;
2756 void *addr = p->addr;
2757
2758 if (p->pre_handler == pre_handler_kretprobe)
2759 kprobe_type = "r";
2760 else
2761 kprobe_type = "k";
2762
2763 if (!kallsyms_show_value(pi->file->f_cred))
2764 addr = NULL;
2765
2766 if (sym)
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);
2773
2774 if (!pp)
2775 pp = p;
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]" : ""));
2781}
2782
2783static void *kprobe_seq_start(struct seq_file *f, loff_t *pos)
2784{
2785 return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
2786}
2787
2788static void *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
2789{
2790 (*pos)++;
2791 if (*pos >= KPROBE_TABLE_SIZE)
2792 return NULL;
2793 return pos;
2794}
2795
2796static void kprobe_seq_stop(struct seq_file *f, void *v)
2797{
2798 /* Nothing to do */
2799}
2800
2801static int show_kprobe_addr(struct seq_file *pi, void *v)
2802{
2803 struct hlist_head *head;
2804 struct kprobe *p, *kp;
2805 const char *sym;
2806 unsigned int i = *(loff_t *) v;
2807 unsigned long offset = 0;
2808 char *modname, namebuf[KSYM_NAME_LEN];
2809
2810 head = &kprobe_table[i];
2811 preempt_disable();
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);
2818 } else
2819 report_probe(pi, p, sym, offset, modname, NULL);
2820 }
2821 preempt_enable();
2822 return 0;
2823}
2824
2825static 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
2830};
2831
2832DEFINE_SEQ_ATTRIBUTE(kprobes);
2833
2834/* kprobes/blacklist -- shows which functions can not be probed */
2835static void *kprobe_blacklist_seq_start(struct seq_file *m, loff_t *pos)
2836{
2837 mutex_lock(&kprobe_mutex);
2838 return seq_list_start(&kprobe_blacklist, *pos);
2839}
2840
2841static void *kprobe_blacklist_seq_next(struct seq_file *m, void *v, loff_t *pos)
2842{
2843 return seq_list_next(v, &kprobe_blacklist, pos);
2844}
2845
2846static int kprobe_blacklist_seq_show(struct seq_file *m, void *v)
2847{
2848 struct kprobe_blacklist_entry *ent =
2849 list_entry(v, struct kprobe_blacklist_entry, list);
2850
2851 /*
2852 * If '/proc/kallsyms' is not showing kernel address, we won't
2853 * show them here either.
2854 */
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);
2858 else
2859 seq_printf(m, "0x%px-0x%px\t%ps\n", (void *)ent->start_addr,
2860 (void *)ent->end_addr, (void *)ent->start_addr);
2861 return 0;
2862}
2863
2864static void kprobe_blacklist_seq_stop(struct seq_file *f, void *v)
2865{
2866 mutex_unlock(&kprobe_mutex);
2867}
2868
2869static 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,
2874};
2875DEFINE_SEQ_ATTRIBUTE(kprobe_blacklist);
2876
2877static int arm_all_kprobes(void)
2878{
2879 struct hlist_head *head;
2880 struct kprobe *p;
2881 unsigned int i, total = 0, errors = 0;
2882 int err, ret = 0;
2883
2884 mutex_lock(&kprobe_mutex);
2885
2886 /* If kprobes are armed, just return */
2887 if (!kprobes_all_disarmed)
2888 goto already_enabled;
2889
2890 /*
2891 * optimize_kprobe() called by arm_kprobe() checks
2892 * kprobes_all_disarmed, so set kprobes_all_disarmed before
2893 * arm_kprobe.
2894 */
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);
2903 if (err) {
2904 errors++;
2905 ret = err;
2906 }
2907 total++;
2908 }
2909 }
2910 }
2911
2912 if (errors)
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",
2914 errors, total);
2915 else
2916 pr_info("Kprobes globally enabled\n");
2917
2918already_enabled:
2919 mutex_unlock(&kprobe_mutex);
2920 return ret;
2921}
2922
2923static int disarm_all_kprobes(void)
2924{
2925 struct hlist_head *head;
2926 struct kprobe *p;
2927 unsigned int i, total = 0, errors = 0;
2928 int err, ret = 0;
2929
2930 mutex_lock(&kprobe_mutex);
2931
2932 /* If kprobes are already disarmed, just return */
2933 if (kprobes_all_disarmed) {
2934 mutex_unlock(&kprobe_mutex);
2935 return 0;
2936 }
2937
2938 kprobes_all_disarmed = true;
2939
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);
2946 if (err) {
2947 errors++;
2948 ret = err;
2949 }
2950 total++;
2951 }
2952 }
2953 }
2954
2955 if (errors)
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",
2957 errors, total);
2958 else
2959 pr_info("Kprobes globally disabled\n");
2960
2961 mutex_unlock(&kprobe_mutex);
2962
2963 /* Wait for disarming all kprobes by optimizer */
2964 wait_for_kprobe_optimizer();
2965
2966 return ret;
2967}
2968
2969/*
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
2972 * available
2973 */
2974static ssize_t read_enabled_file_bool(struct file *file,
2975 char __user *user_buf, size_t count, loff_t *ppos)
2976{
2977 char buf[3];
2978
2979 if (!kprobes_all_disarmed)
2980 buf[0] = '1';
2981 else
2982 buf[0] = '0';
2983 buf[1] = '\n';
2984 buf[2] = 0x00;
2985 return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
2986}
2987
2988static ssize_t write_enabled_file_bool(struct file *file,
2989 const char __user *user_buf, size_t count, loff_t *ppos)
2990{
2991 bool enable;
2992 int ret;
2993
2994 ret = kstrtobool_from_user(user_buf, count, &enable);
2995 if (ret)
2996 return ret;
2997
2998 ret = enable ? arm_all_kprobes() : disarm_all_kprobes();
2999 if (ret)
3000 return ret;
3001
3002 return count;
3003}
3004
3005static const struct file_operations fops_kp = {
3006 .read = read_enabled_file_bool,
3007 .write = write_enabled_file_bool,
3008 .llseek = default_llseek,
3009};
3010
3011static int __init debugfs_kprobe_init(void)
3012{
3013 struct dentry *dir;
3014
3015 dir = debugfs_create_dir("kprobes", NULL);
3016
3017 debugfs_create_file("list", 0400, dir, NULL, &kprobes_fops);
3018
3019 debugfs_create_file("enabled", 0600, dir, NULL, &fops_kp);
3020
3021 debugfs_create_file("blacklist", 0400, dir, NULL,
3022 &kprobe_blacklist_fops);
3023
3024 return 0;
3025}
3026
3027late_initcall(debugfs_kprobe_init);
3028#endif /* CONFIG_DEBUG_FS */
1/*
2 * Kernel Probes (KProbes)
3 * kernel/kprobes.c
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
18 *
19 * Copyright (C) IBM Corporation, 2002, 2004
20 *
21 * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
22 * Probes initial implementation (includes suggestions from
23 * Rusty Russell).
24 * 2004-Aug Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with
25 * hlists and exceptions notifier as suggested by Andi Kleen.
26 * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
27 * interface to access function arguments.
28 * 2004-Sep Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
29 * exceptions notifier to be first on the priority list.
30 * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston
31 * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
32 * <prasanna@in.ibm.com> added function-return probes.
33 */
34#include <linux/kprobes.h>
35#include <linux/hash.h>
36#include <linux/init.h>
37#include <linux/slab.h>
38#include <linux/stddef.h>
39#include <linux/module.h>
40#include <linux/moduleloader.h>
41#include <linux/kallsyms.h>
42#include <linux/freezer.h>
43#include <linux/seq_file.h>
44#include <linux/debugfs.h>
45#include <linux/sysctl.h>
46#include <linux/kdebug.h>
47#include <linux/memory.h>
48#include <linux/ftrace.h>
49#include <linux/cpu.h>
50#include <linux/jump_label.h>
51
52#include <asm-generic/sections.h>
53#include <asm/cacheflush.h>
54#include <asm/errno.h>
55#include <asm/uaccess.h>
56
57#define KPROBE_HASH_BITS 6
58#define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
59
60
61/*
62 * Some oddball architectures like 64bit powerpc have function descriptors
63 * so this must be overridable.
64 */
65#ifndef kprobe_lookup_name
66#define kprobe_lookup_name(name, addr) \
67 addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name)))
68#endif
69
70static int kprobes_initialized;
71static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
72static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
73
74/* NOTE: change this value only with kprobe_mutex held */
75static bool kprobes_all_disarmed;
76
77/* This protects kprobe_table and optimizing_list */
78static DEFINE_MUTEX(kprobe_mutex);
79static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
80static struct {
81 spinlock_t lock ____cacheline_aligned_in_smp;
82} kretprobe_table_locks[KPROBE_TABLE_SIZE];
83
84static spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
85{
86 return &(kretprobe_table_locks[hash].lock);
87}
88
89/*
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)
93 *
94 * For such cases, we now have a blacklist
95 */
96static 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 */
103};
104
105#ifdef __ARCH_WANT_KPROBES_INSN_SLOT
106/*
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
111 */
112struct kprobe_insn_page {
113 struct list_head list;
114 kprobe_opcode_t *insns; /* Page of instruction slots */
115 int nused;
116 int ngarbage;
117 char slot_used[];
118};
119
120#define KPROBE_INSN_PAGE_SIZE(slots) \
121 (offsetof(struct kprobe_insn_page, slot_used) + \
122 (sizeof(char) * (slots)))
123
124struct kprobe_insn_cache {
125 struct list_head pages; /* list of kprobe_insn_page */
126 size_t insn_size; /* size of instruction slot */
127 int nr_garbage;
128};
129
130static int slots_per_page(struct kprobe_insn_cache *c)
131{
132 return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));
133}
134
135enum kprobe_slot_state {
136 SLOT_CLEAN = 0,
137 SLOT_DIRTY = 1,
138 SLOT_USED = 2,
139};
140
141static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_slots */
142static struct kprobe_insn_cache kprobe_insn_slots = {
143 .pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
144 .insn_size = MAX_INSN_SIZE,
145 .nr_garbage = 0,
146};
147static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c);
148
149/**
150 * __get_insn_slot() - Find a slot on an executable page for an instruction.
151 * We allocate an executable page if there's no room on existing ones.
152 */
153static kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
154{
155 struct kprobe_insn_page *kip;
156
157 retry:
158 list_for_each_entry(kip, &c->pages, list) {
159 if (kip->nused < slots_per_page(c)) {
160 int i;
161 for (i = 0; i < slots_per_page(c); i++) {
162 if (kip->slot_used[i] == SLOT_CLEAN) {
163 kip->slot_used[i] = SLOT_USED;
164 kip->nused++;
165 return kip->insns + (i * c->insn_size);
166 }
167 }
168 /* kip->nused is broken. Fix it. */
169 kip->nused = slots_per_page(c);
170 WARN_ON(1);
171 }
172 }
173
174 /* If there are any garbage slots, collect it and try again. */
175 if (c->nr_garbage && collect_garbage_slots(c) == 0)
176 goto retry;
177
178 /* All out of space. Need to allocate a new page. */
179 kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
180 if (!kip)
181 return NULL;
182
183 /*
184 * Use module_alloc so this page is within +/- 2GB of where the
185 * kernel image and loaded module images reside. This is required
186 * so x86_64 can correctly handle the %rip-relative fixups.
187 */
188 kip->insns = module_alloc(PAGE_SIZE);
189 if (!kip->insns) {
190 kfree(kip);
191 return NULL;
192 }
193 INIT_LIST_HEAD(&kip->list);
194 memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c));
195 kip->slot_used[0] = SLOT_USED;
196 kip->nused = 1;
197 kip->ngarbage = 0;
198 list_add(&kip->list, &c->pages);
199 return kip->insns;
200}
201
202
203kprobe_opcode_t __kprobes *get_insn_slot(void)
204{
205 kprobe_opcode_t *ret = NULL;
206
207 mutex_lock(&kprobe_insn_mutex);
208 ret = __get_insn_slot(&kprobe_insn_slots);
209 mutex_unlock(&kprobe_insn_mutex);
210
211 return ret;
212}
213
214/* Return 1 if all garbages are collected, otherwise 0. */
215static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
216{
217 kip->slot_used[idx] = SLOT_CLEAN;
218 kip->nused--;
219 if (kip->nused == 0) {
220 /*
221 * Page is no longer in use. Free it unless
222 * it's the last one. We keep the last one
223 * so as not to have to set it up again the
224 * next time somebody inserts a probe.
225 */
226 if (!list_is_singular(&kip->list)) {
227 list_del(&kip->list);
228 module_free(NULL, kip->insns);
229 kfree(kip);
230 }
231 return 1;
232 }
233 return 0;
234}
235
236static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c)
237{
238 struct kprobe_insn_page *kip, *next;
239
240 /* Ensure no-one is interrupted on the garbages */
241 synchronize_sched();
242
243 list_for_each_entry_safe(kip, next, &c->pages, list) {
244 int i;
245 if (kip->ngarbage == 0)
246 continue;
247 kip->ngarbage = 0; /* we will collect all garbages */
248 for (i = 0; i < slots_per_page(c); i++) {
249 if (kip->slot_used[i] == SLOT_DIRTY &&
250 collect_one_slot(kip, i))
251 break;
252 }
253 }
254 c->nr_garbage = 0;
255 return 0;
256}
257
258static void __kprobes __free_insn_slot(struct kprobe_insn_cache *c,
259 kprobe_opcode_t *slot, int dirty)
260{
261 struct kprobe_insn_page *kip;
262
263 list_for_each_entry(kip, &c->pages, list) {
264 long idx = ((long)slot - (long)kip->insns) /
265 (c->insn_size * sizeof(kprobe_opcode_t));
266 if (idx >= 0 && idx < slots_per_page(c)) {
267 WARN_ON(kip->slot_used[idx] != SLOT_USED);
268 if (dirty) {
269 kip->slot_used[idx] = SLOT_DIRTY;
270 kip->ngarbage++;
271 if (++c->nr_garbage > slots_per_page(c))
272 collect_garbage_slots(c);
273 } else
274 collect_one_slot(kip, idx);
275 return;
276 }
277 }
278 /* Could not free this slot. */
279 WARN_ON(1);
280}
281
282void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
283{
284 mutex_lock(&kprobe_insn_mutex);
285 __free_insn_slot(&kprobe_insn_slots, slot, dirty);
286 mutex_unlock(&kprobe_insn_mutex);
287}
288#ifdef CONFIG_OPTPROBES
289/* For optimized_kprobe buffer */
290static DEFINE_MUTEX(kprobe_optinsn_mutex); /* Protects kprobe_optinsn_slots */
291static struct kprobe_insn_cache kprobe_optinsn_slots = {
292 .pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
293 /* .insn_size is initialized later */
294 .nr_garbage = 0,
295};
296/* Get a slot for optimized_kprobe buffer */
297kprobe_opcode_t __kprobes *get_optinsn_slot(void)
298{
299 kprobe_opcode_t *ret = NULL;
300
301 mutex_lock(&kprobe_optinsn_mutex);
302 ret = __get_insn_slot(&kprobe_optinsn_slots);
303 mutex_unlock(&kprobe_optinsn_mutex);
304
305 return ret;
306}
307
308void __kprobes free_optinsn_slot(kprobe_opcode_t * slot, int dirty)
309{
310 mutex_lock(&kprobe_optinsn_mutex);
311 __free_insn_slot(&kprobe_optinsn_slots, slot, dirty);
312 mutex_unlock(&kprobe_optinsn_mutex);
313}
314#endif
315#endif
316
317/* We have preemption disabled.. so it is safe to use __ versions */
318static inline void set_kprobe_instance(struct kprobe *kp)
319{
320 __this_cpu_write(kprobe_instance, kp);
321}
322
323static inline void reset_kprobe_instance(void)
324{
325 __this_cpu_write(kprobe_instance, NULL);
326}
327
328/*
329 * This routine is called either:
330 * - under the kprobe_mutex - during kprobe_[un]register()
331 * OR
332 * - with preemption disabled - from arch/xxx/kernel/kprobes.c
333 */
334struct kprobe __kprobes *get_kprobe(void *addr)
335{
336 struct hlist_head *head;
337 struct hlist_node *node;
338 struct kprobe *p;
339
340 head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
341 hlist_for_each_entry_rcu(p, node, head, hlist) {
342 if (p->addr == addr)
343 return p;
344 }
345
346 return NULL;
347}
348
349static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs);
350
351/* Return true if the kprobe is an aggregator */
352static inline int kprobe_aggrprobe(struct kprobe *p)
353{
354 return p->pre_handler == aggr_pre_handler;
355}
356
357/* Return true(!0) if the kprobe is unused */
358static inline int kprobe_unused(struct kprobe *p)
359{
360 return kprobe_aggrprobe(p) && kprobe_disabled(p) &&
361 list_empty(&p->list);
362}
363
364/*
365 * Keep all fields in the kprobe consistent
366 */
367static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p)
368{
369 memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t));
370 memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn));
371}
372
373#ifdef CONFIG_OPTPROBES
374/* NOTE: change this value only with kprobe_mutex held */
375static bool kprobes_allow_optimization;
376
377/*
378 * Call all pre_handler on the list, but ignores its return value.
379 * This must be called from arch-dep optimized caller.
380 */
381void __kprobes opt_pre_handler(struct kprobe *p, struct pt_regs *regs)
382{
383 struct kprobe *kp;
384
385 list_for_each_entry_rcu(kp, &p->list, list) {
386 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
387 set_kprobe_instance(kp);
388 kp->pre_handler(kp, regs);
389 }
390 reset_kprobe_instance();
391 }
392}
393
394/* Free optimized instructions and optimized_kprobe */
395static __kprobes void free_aggr_kprobe(struct kprobe *p)
396{
397 struct optimized_kprobe *op;
398
399 op = container_of(p, struct optimized_kprobe, kp);
400 arch_remove_optimized_kprobe(op);
401 arch_remove_kprobe(p);
402 kfree(op);
403}
404
405/* Return true(!0) if the kprobe is ready for optimization. */
406static inline int kprobe_optready(struct kprobe *p)
407{
408 struct optimized_kprobe *op;
409
410 if (kprobe_aggrprobe(p)) {
411 op = container_of(p, struct optimized_kprobe, kp);
412 return arch_prepared_optinsn(&op->optinsn);
413 }
414
415 return 0;
416}
417
418/* Return true(!0) if the kprobe is disarmed. Note: p must be on hash list */
419static inline int kprobe_disarmed(struct kprobe *p)
420{
421 struct optimized_kprobe *op;
422
423 /* If kprobe is not aggr/opt probe, just return kprobe is disabled */
424 if (!kprobe_aggrprobe(p))
425 return kprobe_disabled(p);
426
427 op = container_of(p, struct optimized_kprobe, kp);
428
429 return kprobe_disabled(p) && list_empty(&op->list);
430}
431
432/* Return true(!0) if the probe is queued on (un)optimizing lists */
433static int __kprobes kprobe_queued(struct kprobe *p)
434{
435 struct optimized_kprobe *op;
436
437 if (kprobe_aggrprobe(p)) {
438 op = container_of(p, struct optimized_kprobe, kp);
439 if (!list_empty(&op->list))
440 return 1;
441 }
442 return 0;
443}
444
445/*
446 * Return an optimized kprobe whose optimizing code replaces
447 * instructions including addr (exclude breakpoint).
448 */
449static struct kprobe *__kprobes get_optimized_kprobe(unsigned long addr)
450{
451 int i;
452 struct kprobe *p = NULL;
453 struct optimized_kprobe *op;
454
455 /* Don't check i == 0, since that is a breakpoint case. */
456 for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH; i++)
457 p = get_kprobe((void *)(addr - i));
458
459 if (p && kprobe_optready(p)) {
460 op = container_of(p, struct optimized_kprobe, kp);
461 if (arch_within_optimized_kprobe(op, addr))
462 return p;
463 }
464
465 return NULL;
466}
467
468/* Optimization staging list, protected by kprobe_mutex */
469static LIST_HEAD(optimizing_list);
470static LIST_HEAD(unoptimizing_list);
471
472static void kprobe_optimizer(struct work_struct *work);
473static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
474static DECLARE_COMPLETION(optimizer_comp);
475#define OPTIMIZE_DELAY 5
476
477/*
478 * Optimize (replace a breakpoint with a jump) kprobes listed on
479 * optimizing_list.
480 */
481static __kprobes void do_optimize_kprobes(void)
482{
483 /* Optimization never be done when disarmed */
484 if (kprobes_all_disarmed || !kprobes_allow_optimization ||
485 list_empty(&optimizing_list))
486 return;
487
488 /*
489 * The optimization/unoptimization refers online_cpus via
490 * stop_machine() and cpu-hotplug modifies online_cpus.
491 * And same time, text_mutex will be held in cpu-hotplug and here.
492 * This combination can cause a deadlock (cpu-hotplug try to lock
493 * text_mutex but stop_machine can not be done because online_cpus
494 * has been changed)
495 * To avoid this deadlock, we need to call get_online_cpus()
496 * for preventing cpu-hotplug outside of text_mutex locking.
497 */
498 get_online_cpus();
499 mutex_lock(&text_mutex);
500 arch_optimize_kprobes(&optimizing_list);
501 mutex_unlock(&text_mutex);
502 put_online_cpus();
503}
504
505/*
506 * Unoptimize (replace a jump with a breakpoint and remove the breakpoint
507 * if need) kprobes listed on unoptimizing_list.
508 */
509static __kprobes void do_unoptimize_kprobes(struct list_head *free_list)
510{
511 struct optimized_kprobe *op, *tmp;
512
513 /* Unoptimization must be done anytime */
514 if (list_empty(&unoptimizing_list))
515 return;
516
517 /* Ditto to do_optimize_kprobes */
518 get_online_cpus();
519 mutex_lock(&text_mutex);
520 arch_unoptimize_kprobes(&unoptimizing_list, free_list);
521 /* Loop free_list for disarming */
522 list_for_each_entry_safe(op, tmp, free_list, list) {
523 /* Disarm probes if marked disabled */
524 if (kprobe_disabled(&op->kp))
525 arch_disarm_kprobe(&op->kp);
526 if (kprobe_unused(&op->kp)) {
527 /*
528 * Remove unused probes from hash list. After waiting
529 * for synchronization, these probes are reclaimed.
530 * (reclaiming is done by do_free_cleaned_kprobes.)
531 */
532 hlist_del_rcu(&op->kp.hlist);
533 } else
534 list_del_init(&op->list);
535 }
536 mutex_unlock(&text_mutex);
537 put_online_cpus();
538}
539
540/* Reclaim all kprobes on the free_list */
541static __kprobes void do_free_cleaned_kprobes(struct list_head *free_list)
542{
543 struct optimized_kprobe *op, *tmp;
544
545 list_for_each_entry_safe(op, tmp, free_list, list) {
546 BUG_ON(!kprobe_unused(&op->kp));
547 list_del_init(&op->list);
548 free_aggr_kprobe(&op->kp);
549 }
550}
551
552/* Start optimizer after OPTIMIZE_DELAY passed */
553static __kprobes void kick_kprobe_optimizer(void)
554{
555 if (!delayed_work_pending(&optimizing_work))
556 schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
557}
558
559/* Kprobe jump optimizer */
560static __kprobes void kprobe_optimizer(struct work_struct *work)
561{
562 LIST_HEAD(free_list);
563
564 /* Lock modules while optimizing kprobes */
565 mutex_lock(&module_mutex);
566 mutex_lock(&kprobe_mutex);
567
568 /*
569 * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
570 * kprobes before waiting for quiesence period.
571 */
572 do_unoptimize_kprobes(&free_list);
573
574 /*
575 * Step 2: Wait for quiesence period to ensure all running interrupts
576 * are done. Because optprobe may modify multiple instructions
577 * there is a chance that Nth instruction is interrupted. In that
578 * case, running interrupt can return to 2nd-Nth byte of jump
579 * instruction. This wait is for avoiding it.
580 */
581 synchronize_sched();
582
583 /* Step 3: Optimize kprobes after quiesence period */
584 do_optimize_kprobes();
585
586 /* Step 4: Free cleaned kprobes after quiesence period */
587 do_free_cleaned_kprobes(&free_list);
588
589 mutex_unlock(&kprobe_mutex);
590 mutex_unlock(&module_mutex);
591
592 /* Step 5: Kick optimizer again if needed */
593 if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
594 kick_kprobe_optimizer();
595 else
596 /* Wake up all waiters */
597 complete_all(&optimizer_comp);
598}
599
600/* Wait for completing optimization and unoptimization */
601static __kprobes void wait_for_kprobe_optimizer(void)
602{
603 if (delayed_work_pending(&optimizing_work))
604 wait_for_completion(&optimizer_comp);
605}
606
607/* Optimize kprobe if p is ready to be optimized */
608static __kprobes void optimize_kprobe(struct kprobe *p)
609{
610 struct optimized_kprobe *op;
611
612 /* Check if the kprobe is disabled or not ready for optimization. */
613 if (!kprobe_optready(p) || !kprobes_allow_optimization ||
614 (kprobe_disabled(p) || kprobes_all_disarmed))
615 return;
616
617 /* Both of break_handler and post_handler are not supported. */
618 if (p->break_handler || p->post_handler)
619 return;
620
621 op = container_of(p, struct optimized_kprobe, kp);
622
623 /* Check there is no other kprobes at the optimized instructions */
624 if (arch_check_optimized_kprobe(op) < 0)
625 return;
626
627 /* Check if it is already optimized. */
628 if (op->kp.flags & KPROBE_FLAG_OPTIMIZED)
629 return;
630 op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
631
632 if (!list_empty(&op->list))
633 /* This is under unoptimizing. Just dequeue the probe */
634 list_del_init(&op->list);
635 else {
636 list_add(&op->list, &optimizing_list);
637 kick_kprobe_optimizer();
638 }
639}
640
641/* Short cut to direct unoptimizing */
642static __kprobes void force_unoptimize_kprobe(struct optimized_kprobe *op)
643{
644 get_online_cpus();
645 arch_unoptimize_kprobe(op);
646 put_online_cpus();
647 if (kprobe_disabled(&op->kp))
648 arch_disarm_kprobe(&op->kp);
649}
650
651/* Unoptimize a kprobe if p is optimized */
652static __kprobes void unoptimize_kprobe(struct kprobe *p, bool force)
653{
654 struct optimized_kprobe *op;
655
656 if (!kprobe_aggrprobe(p) || kprobe_disarmed(p))
657 return; /* This is not an optprobe nor optimized */
658
659 op = container_of(p, struct optimized_kprobe, kp);
660 if (!kprobe_optimized(p)) {
661 /* Unoptimized or unoptimizing case */
662 if (force && !list_empty(&op->list)) {
663 /*
664 * Only if this is unoptimizing kprobe and forced,
665 * forcibly unoptimize it. (No need to unoptimize
666 * unoptimized kprobe again :)
667 */
668 list_del_init(&op->list);
669 force_unoptimize_kprobe(op);
670 }
671 return;
672 }
673
674 op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
675 if (!list_empty(&op->list)) {
676 /* Dequeue from the optimization queue */
677 list_del_init(&op->list);
678 return;
679 }
680 /* Optimized kprobe case */
681 if (force)
682 /* Forcibly update the code: this is a special case */
683 force_unoptimize_kprobe(op);
684 else {
685 list_add(&op->list, &unoptimizing_list);
686 kick_kprobe_optimizer();
687 }
688}
689
690/* Cancel unoptimizing for reusing */
691static void reuse_unused_kprobe(struct kprobe *ap)
692{
693 struct optimized_kprobe *op;
694
695 BUG_ON(!kprobe_unused(ap));
696 /*
697 * Unused kprobe MUST be on the way of delayed unoptimizing (means
698 * there is still a relative jump) and disabled.
699 */
700 op = container_of(ap, struct optimized_kprobe, kp);
701 if (unlikely(list_empty(&op->list)))
702 printk(KERN_WARNING "Warning: found a stray unused "
703 "aggrprobe@%p\n", ap->addr);
704 /* Enable the probe again */
705 ap->flags &= ~KPROBE_FLAG_DISABLED;
706 /* Optimize it again (remove from op->list) */
707 BUG_ON(!kprobe_optready(ap));
708 optimize_kprobe(ap);
709}
710
711/* Remove optimized instructions */
712static void __kprobes kill_optimized_kprobe(struct kprobe *p)
713{
714 struct optimized_kprobe *op;
715
716 op = container_of(p, struct optimized_kprobe, kp);
717 if (!list_empty(&op->list))
718 /* Dequeue from the (un)optimization queue */
719 list_del_init(&op->list);
720
721 op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
722 /* Don't touch the code, because it is already freed. */
723 arch_remove_optimized_kprobe(op);
724}
725
726/* Try to prepare optimized instructions */
727static __kprobes void prepare_optimized_kprobe(struct kprobe *p)
728{
729 struct optimized_kprobe *op;
730
731 op = container_of(p, struct optimized_kprobe, kp);
732 arch_prepare_optimized_kprobe(op);
733}
734
735/* Allocate new optimized_kprobe and try to prepare optimized instructions */
736static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
737{
738 struct optimized_kprobe *op;
739
740 op = kzalloc(sizeof(struct optimized_kprobe), GFP_KERNEL);
741 if (!op)
742 return NULL;
743
744 INIT_LIST_HEAD(&op->list);
745 op->kp.addr = p->addr;
746 arch_prepare_optimized_kprobe(op);
747
748 return &op->kp;
749}
750
751static void __kprobes init_aggr_kprobe(struct kprobe *ap, struct kprobe *p);
752
753/*
754 * Prepare an optimized_kprobe and optimize it
755 * NOTE: p must be a normal registered kprobe
756 */
757static __kprobes void try_to_optimize_kprobe(struct kprobe *p)
758{
759 struct kprobe *ap;
760 struct optimized_kprobe *op;
761
762 ap = alloc_aggr_kprobe(p);
763 if (!ap)
764 return;
765
766 op = container_of(ap, struct optimized_kprobe, kp);
767 if (!arch_prepared_optinsn(&op->optinsn)) {
768 /* If failed to setup optimizing, fallback to kprobe */
769 arch_remove_optimized_kprobe(op);
770 kfree(op);
771 return;
772 }
773
774 init_aggr_kprobe(ap, p);
775 optimize_kprobe(ap);
776}
777
778#ifdef CONFIG_SYSCTL
779/* This should be called with kprobe_mutex locked */
780static void __kprobes optimize_all_kprobes(void)
781{
782 struct hlist_head *head;
783 struct hlist_node *node;
784 struct kprobe *p;
785 unsigned int i;
786
787 /* If optimization is already allowed, just return */
788 if (kprobes_allow_optimization)
789 return;
790
791 kprobes_allow_optimization = true;
792 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
793 head = &kprobe_table[i];
794 hlist_for_each_entry_rcu(p, node, head, hlist)
795 if (!kprobe_disabled(p))
796 optimize_kprobe(p);
797 }
798 printk(KERN_INFO "Kprobes globally optimized\n");
799}
800
801/* This should be called with kprobe_mutex locked */
802static void __kprobes unoptimize_all_kprobes(void)
803{
804 struct hlist_head *head;
805 struct hlist_node *node;
806 struct kprobe *p;
807 unsigned int i;
808
809 /* If optimization is already prohibited, just return */
810 if (!kprobes_allow_optimization)
811 return;
812
813 kprobes_allow_optimization = false;
814 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
815 head = &kprobe_table[i];
816 hlist_for_each_entry_rcu(p, node, head, hlist) {
817 if (!kprobe_disabled(p))
818 unoptimize_kprobe(p, false);
819 }
820 }
821 /* Wait for unoptimizing completion */
822 wait_for_kprobe_optimizer();
823 printk(KERN_INFO "Kprobes globally unoptimized\n");
824}
825
826int sysctl_kprobes_optimization;
827int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
828 void __user *buffer, size_t *length,
829 loff_t *ppos)
830{
831 int ret;
832
833 mutex_lock(&kprobe_mutex);
834 sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0;
835 ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
836
837 if (sysctl_kprobes_optimization)
838 optimize_all_kprobes();
839 else
840 unoptimize_all_kprobes();
841 mutex_unlock(&kprobe_mutex);
842
843 return ret;
844}
845#endif /* CONFIG_SYSCTL */
846
847/* Put a breakpoint for a probe. Must be called with text_mutex locked */
848static void __kprobes __arm_kprobe(struct kprobe *p)
849{
850 struct kprobe *_p;
851
852 /* Check collision with other optimized kprobes */
853 _p = get_optimized_kprobe((unsigned long)p->addr);
854 if (unlikely(_p))
855 /* Fallback to unoptimized kprobe */
856 unoptimize_kprobe(_p, true);
857
858 arch_arm_kprobe(p);
859 optimize_kprobe(p); /* Try to optimize (add kprobe to a list) */
860}
861
862/* Remove the breakpoint of a probe. Must be called with text_mutex locked */
863static void __kprobes __disarm_kprobe(struct kprobe *p, bool reopt)
864{
865 struct kprobe *_p;
866
867 unoptimize_kprobe(p, false); /* Try to unoptimize */
868
869 if (!kprobe_queued(p)) {
870 arch_disarm_kprobe(p);
871 /* If another kprobe was blocked, optimize it. */
872 _p = get_optimized_kprobe((unsigned long)p->addr);
873 if (unlikely(_p) && reopt)
874 optimize_kprobe(_p);
875 }
876 /* TODO: reoptimize others after unoptimized this probe */
877}
878
879#else /* !CONFIG_OPTPROBES */
880
881#define optimize_kprobe(p) do {} while (0)
882#define unoptimize_kprobe(p, f) do {} while (0)
883#define kill_optimized_kprobe(p) do {} while (0)
884#define prepare_optimized_kprobe(p) do {} while (0)
885#define try_to_optimize_kprobe(p) do {} while (0)
886#define __arm_kprobe(p) arch_arm_kprobe(p)
887#define __disarm_kprobe(p, o) arch_disarm_kprobe(p)
888#define kprobe_disarmed(p) kprobe_disabled(p)
889#define wait_for_kprobe_optimizer() do {} while (0)
890
891/* There should be no unused kprobes can be reused without optimization */
892static void reuse_unused_kprobe(struct kprobe *ap)
893{
894 printk(KERN_ERR "Error: There should be no unused kprobe here.\n");
895 BUG_ON(kprobe_unused(ap));
896}
897
898static __kprobes void free_aggr_kprobe(struct kprobe *p)
899{
900 arch_remove_kprobe(p);
901 kfree(p);
902}
903
904static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
905{
906 return kzalloc(sizeof(struct kprobe), GFP_KERNEL);
907}
908#endif /* CONFIG_OPTPROBES */
909
910/* Arm a kprobe with text_mutex */
911static void __kprobes arm_kprobe(struct kprobe *kp)
912{
913 /*
914 * Here, since __arm_kprobe() doesn't use stop_machine(),
915 * this doesn't cause deadlock on text_mutex. So, we don't
916 * need get_online_cpus().
917 */
918 mutex_lock(&text_mutex);
919 __arm_kprobe(kp);
920 mutex_unlock(&text_mutex);
921}
922
923/* Disarm a kprobe with text_mutex */
924static void __kprobes disarm_kprobe(struct kprobe *kp)
925{
926 /* Ditto */
927 mutex_lock(&text_mutex);
928 __disarm_kprobe(kp, true);
929 mutex_unlock(&text_mutex);
930}
931
932/*
933 * Aggregate handlers for multiple kprobes support - these handlers
934 * take care of invoking the individual kprobe handlers on p->list
935 */
936static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
937{
938 struct kprobe *kp;
939
940 list_for_each_entry_rcu(kp, &p->list, list) {
941 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
942 set_kprobe_instance(kp);
943 if (kp->pre_handler(kp, regs))
944 return 1;
945 }
946 reset_kprobe_instance();
947 }
948 return 0;
949}
950
951static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
952 unsigned long flags)
953{
954 struct kprobe *kp;
955
956 list_for_each_entry_rcu(kp, &p->list, list) {
957 if (kp->post_handler && likely(!kprobe_disabled(kp))) {
958 set_kprobe_instance(kp);
959 kp->post_handler(kp, regs, flags);
960 reset_kprobe_instance();
961 }
962 }
963}
964
965static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
966 int trapnr)
967{
968 struct kprobe *cur = __this_cpu_read(kprobe_instance);
969
970 /*
971 * if we faulted "during" the execution of a user specified
972 * probe handler, invoke just that probe's fault handler
973 */
974 if (cur && cur->fault_handler) {
975 if (cur->fault_handler(cur, regs, trapnr))
976 return 1;
977 }
978 return 0;
979}
980
981static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
982{
983 struct kprobe *cur = __this_cpu_read(kprobe_instance);
984 int ret = 0;
985
986 if (cur && cur->break_handler) {
987 if (cur->break_handler(cur, regs))
988 ret = 1;
989 }
990 reset_kprobe_instance();
991 return ret;
992}
993
994/* Walks the list and increments nmissed count for multiprobe case */
995void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
996{
997 struct kprobe *kp;
998 if (!kprobe_aggrprobe(p)) {
999 p->nmissed++;
1000 } else {
1001 list_for_each_entry_rcu(kp, &p->list, list)
1002 kp->nmissed++;
1003 }
1004 return;
1005}
1006
1007void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
1008 struct hlist_head *head)
1009{
1010 struct kretprobe *rp = ri->rp;
1011
1012 /* remove rp inst off the rprobe_inst_table */
1013 hlist_del(&ri->hlist);
1014 INIT_HLIST_NODE(&ri->hlist);
1015 if (likely(rp)) {
1016 spin_lock(&rp->lock);
1017 hlist_add_head(&ri->hlist, &rp->free_instances);
1018 spin_unlock(&rp->lock);
1019 } else
1020 /* Unregistering */
1021 hlist_add_head(&ri->hlist, head);
1022}
1023
1024void __kprobes kretprobe_hash_lock(struct task_struct *tsk,
1025 struct hlist_head **head, unsigned long *flags)
1026__acquires(hlist_lock)
1027{
1028 unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1029 spinlock_t *hlist_lock;
1030
1031 *head = &kretprobe_inst_table[hash];
1032 hlist_lock = kretprobe_table_lock_ptr(hash);
1033 spin_lock_irqsave(hlist_lock, *flags);
1034}
1035
1036static void __kprobes kretprobe_table_lock(unsigned long hash,
1037 unsigned long *flags)
1038__acquires(hlist_lock)
1039{
1040 spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1041 spin_lock_irqsave(hlist_lock, *flags);
1042}
1043
1044void __kprobes kretprobe_hash_unlock(struct task_struct *tsk,
1045 unsigned long *flags)
1046__releases(hlist_lock)
1047{
1048 unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1049 spinlock_t *hlist_lock;
1050
1051 hlist_lock = kretprobe_table_lock_ptr(hash);
1052 spin_unlock_irqrestore(hlist_lock, *flags);
1053}
1054
1055static void __kprobes kretprobe_table_unlock(unsigned long hash,
1056 unsigned long *flags)
1057__releases(hlist_lock)
1058{
1059 spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1060 spin_unlock_irqrestore(hlist_lock, *flags);
1061}
1062
1063/*
1064 * This function is called from finish_task_switch when task tk becomes dead,
1065 * so that we can recycle any function-return probe instances associated
1066 * with this task. These left over instances represent probed functions
1067 * that have been called but will never return.
1068 */
1069void __kprobes kprobe_flush_task(struct task_struct *tk)
1070{
1071 struct kretprobe_instance *ri;
1072 struct hlist_head *head, empty_rp;
1073 struct hlist_node *node, *tmp;
1074 unsigned long hash, flags = 0;
1075
1076 if (unlikely(!kprobes_initialized))
1077 /* Early boot. kretprobe_table_locks not yet initialized. */
1078 return;
1079
1080 hash = hash_ptr(tk, KPROBE_HASH_BITS);
1081 head = &kretprobe_inst_table[hash];
1082 kretprobe_table_lock(hash, &flags);
1083 hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
1084 if (ri->task == tk)
1085 recycle_rp_inst(ri, &empty_rp);
1086 }
1087 kretprobe_table_unlock(hash, &flags);
1088 INIT_HLIST_HEAD(&empty_rp);
1089 hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
1090 hlist_del(&ri->hlist);
1091 kfree(ri);
1092 }
1093}
1094
1095static inline void free_rp_inst(struct kretprobe *rp)
1096{
1097 struct kretprobe_instance *ri;
1098 struct hlist_node *pos, *next;
1099
1100 hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, hlist) {
1101 hlist_del(&ri->hlist);
1102 kfree(ri);
1103 }
1104}
1105
1106static void __kprobes cleanup_rp_inst(struct kretprobe *rp)
1107{
1108 unsigned long flags, hash;
1109 struct kretprobe_instance *ri;
1110 struct hlist_node *pos, *next;
1111 struct hlist_head *head;
1112
1113 /* No race here */
1114 for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
1115 kretprobe_table_lock(hash, &flags);
1116 head = &kretprobe_inst_table[hash];
1117 hlist_for_each_entry_safe(ri, pos, next, head, hlist) {
1118 if (ri->rp == rp)
1119 ri->rp = NULL;
1120 }
1121 kretprobe_table_unlock(hash, &flags);
1122 }
1123 free_rp_inst(rp);
1124}
1125
1126/*
1127* Add the new probe to ap->list. Fail if this is the
1128* second jprobe at the address - two jprobes can't coexist
1129*/
1130static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p)
1131{
1132 BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
1133
1134 if (p->break_handler || p->post_handler)
1135 unoptimize_kprobe(ap, true); /* Fall back to normal kprobe */
1136
1137 if (p->break_handler) {
1138 if (ap->break_handler)
1139 return -EEXIST;
1140 list_add_tail_rcu(&p->list, &ap->list);
1141 ap->break_handler = aggr_break_handler;
1142 } else
1143 list_add_rcu(&p->list, &ap->list);
1144 if (p->post_handler && !ap->post_handler)
1145 ap->post_handler = aggr_post_handler;
1146
1147 if (kprobe_disabled(ap) && !kprobe_disabled(p)) {
1148 ap->flags &= ~KPROBE_FLAG_DISABLED;
1149 if (!kprobes_all_disarmed)
1150 /* Arm the breakpoint again. */
1151 __arm_kprobe(ap);
1152 }
1153 return 0;
1154}
1155
1156/*
1157 * Fill in the required fields of the "manager kprobe". Replace the
1158 * earlier kprobe in the hlist with the manager kprobe
1159 */
1160static void __kprobes init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
1161{
1162 /* Copy p's insn slot to ap */
1163 copy_kprobe(p, ap);
1164 flush_insn_slot(ap);
1165 ap->addr = p->addr;
1166 ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED;
1167 ap->pre_handler = aggr_pre_handler;
1168 ap->fault_handler = aggr_fault_handler;
1169 /* We don't care the kprobe which has gone. */
1170 if (p->post_handler && !kprobe_gone(p))
1171 ap->post_handler = aggr_post_handler;
1172 if (p->break_handler && !kprobe_gone(p))
1173 ap->break_handler = aggr_break_handler;
1174
1175 INIT_LIST_HEAD(&ap->list);
1176 INIT_HLIST_NODE(&ap->hlist);
1177
1178 list_add_rcu(&p->list, &ap->list);
1179 hlist_replace_rcu(&p->hlist, &ap->hlist);
1180}
1181
1182/*
1183 * This is the second or subsequent kprobe at the address - handle
1184 * the intricacies
1185 */
1186static int __kprobes register_aggr_kprobe(struct kprobe *orig_p,
1187 struct kprobe *p)
1188{
1189 int ret = 0;
1190 struct kprobe *ap = orig_p;
1191
1192 if (!kprobe_aggrprobe(orig_p)) {
1193 /* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */
1194 ap = alloc_aggr_kprobe(orig_p);
1195 if (!ap)
1196 return -ENOMEM;
1197 init_aggr_kprobe(ap, orig_p);
1198 } else if (kprobe_unused(ap))
1199 /* This probe is going to die. Rescue it */
1200 reuse_unused_kprobe(ap);
1201
1202 if (kprobe_gone(ap)) {
1203 /*
1204 * Attempting to insert new probe at the same location that
1205 * had a probe in the module vaddr area which already
1206 * freed. So, the instruction slot has already been
1207 * released. We need a new slot for the new probe.
1208 */
1209 ret = arch_prepare_kprobe(ap);
1210 if (ret)
1211 /*
1212 * Even if fail to allocate new slot, don't need to
1213 * free aggr_probe. It will be used next time, or
1214 * freed by unregister_kprobe.
1215 */
1216 return ret;
1217
1218 /* Prepare optimized instructions if possible. */
1219 prepare_optimized_kprobe(ap);
1220
1221 /*
1222 * Clear gone flag to prevent allocating new slot again, and
1223 * set disabled flag because it is not armed yet.
1224 */
1225 ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
1226 | KPROBE_FLAG_DISABLED;
1227 }
1228
1229 /* Copy ap's insn slot to p */
1230 copy_kprobe(ap, p);
1231 return add_new_kprobe(ap, p);
1232}
1233
1234static int __kprobes in_kprobes_functions(unsigned long addr)
1235{
1236 struct kprobe_blackpoint *kb;
1237
1238 if (addr >= (unsigned long)__kprobes_text_start &&
1239 addr < (unsigned long)__kprobes_text_end)
1240 return -EINVAL;
1241 /*
1242 * If there exists a kprobe_blacklist, verify and
1243 * fail any probe registration in the prohibited area
1244 */
1245 for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
1246 if (kb->start_addr) {
1247 if (addr >= kb->start_addr &&
1248 addr < (kb->start_addr + kb->range))
1249 return -EINVAL;
1250 }
1251 }
1252 return 0;
1253}
1254
1255/*
1256 * If we have a symbol_name argument, look it up and add the offset field
1257 * to it. This way, we can specify a relative address to a symbol.
1258 * This returns encoded errors if it fails to look up symbol or invalid
1259 * combination of parameters.
1260 */
1261static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p)
1262{
1263 kprobe_opcode_t *addr = p->addr;
1264
1265 if ((p->symbol_name && p->addr) ||
1266 (!p->symbol_name && !p->addr))
1267 goto invalid;
1268
1269 if (p->symbol_name) {
1270 kprobe_lookup_name(p->symbol_name, addr);
1271 if (!addr)
1272 return ERR_PTR(-ENOENT);
1273 }
1274
1275 addr = (kprobe_opcode_t *)(((char *)addr) + p->offset);
1276 if (addr)
1277 return addr;
1278
1279invalid:
1280 return ERR_PTR(-EINVAL);
1281}
1282
1283/* Check passed kprobe is valid and return kprobe in kprobe_table. */
1284static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p)
1285{
1286 struct kprobe *ap, *list_p;
1287
1288 ap = get_kprobe(p->addr);
1289 if (unlikely(!ap))
1290 return NULL;
1291
1292 if (p != ap) {
1293 list_for_each_entry_rcu(list_p, &ap->list, list)
1294 if (list_p == p)
1295 /* kprobe p is a valid probe */
1296 goto valid;
1297 return NULL;
1298 }
1299valid:
1300 return ap;
1301}
1302
1303/* Return error if the kprobe is being re-registered */
1304static inline int check_kprobe_rereg(struct kprobe *p)
1305{
1306 int ret = 0;
1307
1308 mutex_lock(&kprobe_mutex);
1309 if (__get_valid_kprobe(p))
1310 ret = -EINVAL;
1311 mutex_unlock(&kprobe_mutex);
1312
1313 return ret;
1314}
1315
1316int __kprobes register_kprobe(struct kprobe *p)
1317{
1318 int ret = 0;
1319 struct kprobe *old_p;
1320 struct module *probed_mod;
1321 kprobe_opcode_t *addr;
1322
1323 addr = kprobe_addr(p);
1324 if (IS_ERR(addr))
1325 return PTR_ERR(addr);
1326 p->addr = addr;
1327
1328 ret = check_kprobe_rereg(p);
1329 if (ret)
1330 return ret;
1331
1332 jump_label_lock();
1333 preempt_disable();
1334 if (!kernel_text_address((unsigned long) p->addr) ||
1335 in_kprobes_functions((unsigned long) p->addr) ||
1336 ftrace_text_reserved(p->addr, p->addr) ||
1337 jump_label_text_reserved(p->addr, p->addr))
1338 goto fail_with_jump_label;
1339
1340 /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
1341 p->flags &= KPROBE_FLAG_DISABLED;
1342
1343 /*
1344 * Check if are we probing a module.
1345 */
1346 probed_mod = __module_text_address((unsigned long) p->addr);
1347 if (probed_mod) {
1348 /* Return -ENOENT if fail. */
1349 ret = -ENOENT;
1350 /*
1351 * We must hold a refcount of the probed module while updating
1352 * its code to prohibit unexpected unloading.
1353 */
1354 if (unlikely(!try_module_get(probed_mod)))
1355 goto fail_with_jump_label;
1356
1357 /*
1358 * If the module freed .init.text, we couldn't insert
1359 * kprobes in there.
1360 */
1361 if (within_module_init((unsigned long)p->addr, probed_mod) &&
1362 probed_mod->state != MODULE_STATE_COMING) {
1363 module_put(probed_mod);
1364 goto fail_with_jump_label;
1365 }
1366 /* ret will be updated by following code */
1367 }
1368 preempt_enable();
1369 jump_label_unlock();
1370
1371 p->nmissed = 0;
1372 INIT_LIST_HEAD(&p->list);
1373 mutex_lock(&kprobe_mutex);
1374
1375 jump_label_lock(); /* needed to call jump_label_text_reserved() */
1376
1377 get_online_cpus(); /* For avoiding text_mutex deadlock. */
1378 mutex_lock(&text_mutex);
1379
1380 old_p = get_kprobe(p->addr);
1381 if (old_p) {
1382 /* Since this may unoptimize old_p, locking text_mutex. */
1383 ret = register_aggr_kprobe(old_p, p);
1384 goto out;
1385 }
1386
1387 ret = arch_prepare_kprobe(p);
1388 if (ret)
1389 goto out;
1390
1391 INIT_HLIST_NODE(&p->hlist);
1392 hlist_add_head_rcu(&p->hlist,
1393 &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
1394
1395 if (!kprobes_all_disarmed && !kprobe_disabled(p))
1396 __arm_kprobe(p);
1397
1398 /* Try to optimize kprobe */
1399 try_to_optimize_kprobe(p);
1400
1401out:
1402 mutex_unlock(&text_mutex);
1403 put_online_cpus();
1404 jump_label_unlock();
1405 mutex_unlock(&kprobe_mutex);
1406
1407 if (probed_mod)
1408 module_put(probed_mod);
1409
1410 return ret;
1411
1412fail_with_jump_label:
1413 preempt_enable();
1414 jump_label_unlock();
1415 return ret;
1416}
1417EXPORT_SYMBOL_GPL(register_kprobe);
1418
1419/* Check if all probes on the aggrprobe are disabled */
1420static int __kprobes aggr_kprobe_disabled(struct kprobe *ap)
1421{
1422 struct kprobe *kp;
1423
1424 list_for_each_entry_rcu(kp, &ap->list, list)
1425 if (!kprobe_disabled(kp))
1426 /*
1427 * There is an active probe on the list.
1428 * We can't disable this ap.
1429 */
1430 return 0;
1431
1432 return 1;
1433}
1434
1435/* Disable one kprobe: Make sure called under kprobe_mutex is locked */
1436static struct kprobe *__kprobes __disable_kprobe(struct kprobe *p)
1437{
1438 struct kprobe *orig_p;
1439
1440 /* Get an original kprobe for return */
1441 orig_p = __get_valid_kprobe(p);
1442 if (unlikely(orig_p == NULL))
1443 return NULL;
1444
1445 if (!kprobe_disabled(p)) {
1446 /* Disable probe if it is a child probe */
1447 if (p != orig_p)
1448 p->flags |= KPROBE_FLAG_DISABLED;
1449
1450 /* Try to disarm and disable this/parent probe */
1451 if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
1452 disarm_kprobe(orig_p);
1453 orig_p->flags |= KPROBE_FLAG_DISABLED;
1454 }
1455 }
1456
1457 return orig_p;
1458}
1459
1460/*
1461 * Unregister a kprobe without a scheduler synchronization.
1462 */
1463static int __kprobes __unregister_kprobe_top(struct kprobe *p)
1464{
1465 struct kprobe *ap, *list_p;
1466
1467 /* Disable kprobe. This will disarm it if needed. */
1468 ap = __disable_kprobe(p);
1469 if (ap == NULL)
1470 return -EINVAL;
1471
1472 if (ap == p)
1473 /*
1474 * This probe is an independent(and non-optimized) kprobe
1475 * (not an aggrprobe). Remove from the hash list.
1476 */
1477 goto disarmed;
1478
1479 /* Following process expects this probe is an aggrprobe */
1480 WARN_ON(!kprobe_aggrprobe(ap));
1481
1482 if (list_is_singular(&ap->list) && kprobe_disarmed(ap))
1483 /*
1484 * !disarmed could be happen if the probe is under delayed
1485 * unoptimizing.
1486 */
1487 goto disarmed;
1488 else {
1489 /* If disabling probe has special handlers, update aggrprobe */
1490 if (p->break_handler && !kprobe_gone(p))
1491 ap->break_handler = NULL;
1492 if (p->post_handler && !kprobe_gone(p)) {
1493 list_for_each_entry_rcu(list_p, &ap->list, list) {
1494 if ((list_p != p) && (list_p->post_handler))
1495 goto noclean;
1496 }
1497 ap->post_handler = NULL;
1498 }
1499noclean:
1500 /*
1501 * Remove from the aggrprobe: this path will do nothing in
1502 * __unregister_kprobe_bottom().
1503 */
1504 list_del_rcu(&p->list);
1505 if (!kprobe_disabled(ap) && !kprobes_all_disarmed)
1506 /*
1507 * Try to optimize this probe again, because post
1508 * handler may have been changed.
1509 */
1510 optimize_kprobe(ap);
1511 }
1512 return 0;
1513
1514disarmed:
1515 BUG_ON(!kprobe_disarmed(ap));
1516 hlist_del_rcu(&ap->hlist);
1517 return 0;
1518}
1519
1520static void __kprobes __unregister_kprobe_bottom(struct kprobe *p)
1521{
1522 struct kprobe *ap;
1523
1524 if (list_empty(&p->list))
1525 /* This is an independent kprobe */
1526 arch_remove_kprobe(p);
1527 else if (list_is_singular(&p->list)) {
1528 /* This is the last child of an aggrprobe */
1529 ap = list_entry(p->list.next, struct kprobe, list);
1530 list_del(&p->list);
1531 free_aggr_kprobe(ap);
1532 }
1533 /* Otherwise, do nothing. */
1534}
1535
1536int __kprobes register_kprobes(struct kprobe **kps, int num)
1537{
1538 int i, ret = 0;
1539
1540 if (num <= 0)
1541 return -EINVAL;
1542 for (i = 0; i < num; i++) {
1543 ret = register_kprobe(kps[i]);
1544 if (ret < 0) {
1545 if (i > 0)
1546 unregister_kprobes(kps, i);
1547 break;
1548 }
1549 }
1550 return ret;
1551}
1552EXPORT_SYMBOL_GPL(register_kprobes);
1553
1554void __kprobes unregister_kprobe(struct kprobe *p)
1555{
1556 unregister_kprobes(&p, 1);
1557}
1558EXPORT_SYMBOL_GPL(unregister_kprobe);
1559
1560void __kprobes unregister_kprobes(struct kprobe **kps, int num)
1561{
1562 int i;
1563
1564 if (num <= 0)
1565 return;
1566 mutex_lock(&kprobe_mutex);
1567 for (i = 0; i < num; i++)
1568 if (__unregister_kprobe_top(kps[i]) < 0)
1569 kps[i]->addr = NULL;
1570 mutex_unlock(&kprobe_mutex);
1571
1572 synchronize_sched();
1573 for (i = 0; i < num; i++)
1574 if (kps[i]->addr)
1575 __unregister_kprobe_bottom(kps[i]);
1576}
1577EXPORT_SYMBOL_GPL(unregister_kprobes);
1578
1579static struct notifier_block kprobe_exceptions_nb = {
1580 .notifier_call = kprobe_exceptions_notify,
1581 .priority = 0x7fffffff /* we need to be notified first */
1582};
1583
1584unsigned long __weak arch_deref_entry_point(void *entry)
1585{
1586 return (unsigned long)entry;
1587}
1588
1589int __kprobes register_jprobes(struct jprobe **jps, int num)
1590{
1591 struct jprobe *jp;
1592 int ret = 0, i;
1593
1594 if (num <= 0)
1595 return -EINVAL;
1596 for (i = 0; i < num; i++) {
1597 unsigned long addr, offset;
1598 jp = jps[i];
1599 addr = arch_deref_entry_point(jp->entry);
1600
1601 /* Verify probepoint is a function entry point */
1602 if (kallsyms_lookup_size_offset(addr, NULL, &offset) &&
1603 offset == 0) {
1604 jp->kp.pre_handler = setjmp_pre_handler;
1605 jp->kp.break_handler = longjmp_break_handler;
1606 ret = register_kprobe(&jp->kp);
1607 } else
1608 ret = -EINVAL;
1609
1610 if (ret < 0) {
1611 if (i > 0)
1612 unregister_jprobes(jps, i);
1613 break;
1614 }
1615 }
1616 return ret;
1617}
1618EXPORT_SYMBOL_GPL(register_jprobes);
1619
1620int __kprobes register_jprobe(struct jprobe *jp)
1621{
1622 return register_jprobes(&jp, 1);
1623}
1624EXPORT_SYMBOL_GPL(register_jprobe);
1625
1626void __kprobes unregister_jprobe(struct jprobe *jp)
1627{
1628 unregister_jprobes(&jp, 1);
1629}
1630EXPORT_SYMBOL_GPL(unregister_jprobe);
1631
1632void __kprobes unregister_jprobes(struct jprobe **jps, int num)
1633{
1634 int i;
1635
1636 if (num <= 0)
1637 return;
1638 mutex_lock(&kprobe_mutex);
1639 for (i = 0; i < num; i++)
1640 if (__unregister_kprobe_top(&jps[i]->kp) < 0)
1641 jps[i]->kp.addr = NULL;
1642 mutex_unlock(&kprobe_mutex);
1643
1644 synchronize_sched();
1645 for (i = 0; i < num; i++) {
1646 if (jps[i]->kp.addr)
1647 __unregister_kprobe_bottom(&jps[i]->kp);
1648 }
1649}
1650EXPORT_SYMBOL_GPL(unregister_jprobes);
1651
1652#ifdef CONFIG_KRETPROBES
1653/*
1654 * This kprobe pre_handler is registered with every kretprobe. When probe
1655 * hits it will set up the return probe.
1656 */
1657static int __kprobes pre_handler_kretprobe(struct kprobe *p,
1658 struct pt_regs *regs)
1659{
1660 struct kretprobe *rp = container_of(p, struct kretprobe, kp);
1661 unsigned long hash, flags = 0;
1662 struct kretprobe_instance *ri;
1663
1664 /*TODO: consider to only swap the RA after the last pre_handler fired */
1665 hash = hash_ptr(current, KPROBE_HASH_BITS);
1666 spin_lock_irqsave(&rp->lock, flags);
1667 if (!hlist_empty(&rp->free_instances)) {
1668 ri = hlist_entry(rp->free_instances.first,
1669 struct kretprobe_instance, hlist);
1670 hlist_del(&ri->hlist);
1671 spin_unlock_irqrestore(&rp->lock, flags);
1672
1673 ri->rp = rp;
1674 ri->task = current;
1675
1676 if (rp->entry_handler && rp->entry_handler(ri, regs))
1677 return 0;
1678
1679 arch_prepare_kretprobe(ri, regs);
1680
1681 /* XXX(hch): why is there no hlist_move_head? */
1682 INIT_HLIST_NODE(&ri->hlist);
1683 kretprobe_table_lock(hash, &flags);
1684 hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
1685 kretprobe_table_unlock(hash, &flags);
1686 } else {
1687 rp->nmissed++;
1688 spin_unlock_irqrestore(&rp->lock, flags);
1689 }
1690 return 0;
1691}
1692
1693int __kprobes register_kretprobe(struct kretprobe *rp)
1694{
1695 int ret = 0;
1696 struct kretprobe_instance *inst;
1697 int i;
1698 void *addr;
1699
1700 if (kretprobe_blacklist_size) {
1701 addr = kprobe_addr(&rp->kp);
1702 if (IS_ERR(addr))
1703 return PTR_ERR(addr);
1704
1705 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1706 if (kretprobe_blacklist[i].addr == addr)
1707 return -EINVAL;
1708 }
1709 }
1710
1711 rp->kp.pre_handler = pre_handler_kretprobe;
1712 rp->kp.post_handler = NULL;
1713 rp->kp.fault_handler = NULL;
1714 rp->kp.break_handler = NULL;
1715
1716 /* Pre-allocate memory for max kretprobe instances */
1717 if (rp->maxactive <= 0) {
1718#ifdef CONFIG_PREEMPT
1719 rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
1720#else
1721 rp->maxactive = num_possible_cpus();
1722#endif
1723 }
1724 spin_lock_init(&rp->lock);
1725 INIT_HLIST_HEAD(&rp->free_instances);
1726 for (i = 0; i < rp->maxactive; i++) {
1727 inst = kmalloc(sizeof(struct kretprobe_instance) +
1728 rp->data_size, GFP_KERNEL);
1729 if (inst == NULL) {
1730 free_rp_inst(rp);
1731 return -ENOMEM;
1732 }
1733 INIT_HLIST_NODE(&inst->hlist);
1734 hlist_add_head(&inst->hlist, &rp->free_instances);
1735 }
1736
1737 rp->nmissed = 0;
1738 /* Establish function entry probe point */
1739 ret = register_kprobe(&rp->kp);
1740 if (ret != 0)
1741 free_rp_inst(rp);
1742 return ret;
1743}
1744EXPORT_SYMBOL_GPL(register_kretprobe);
1745
1746int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1747{
1748 int ret = 0, i;
1749
1750 if (num <= 0)
1751 return -EINVAL;
1752 for (i = 0; i < num; i++) {
1753 ret = register_kretprobe(rps[i]);
1754 if (ret < 0) {
1755 if (i > 0)
1756 unregister_kretprobes(rps, i);
1757 break;
1758 }
1759 }
1760 return ret;
1761}
1762EXPORT_SYMBOL_GPL(register_kretprobes);
1763
1764void __kprobes unregister_kretprobe(struct kretprobe *rp)
1765{
1766 unregister_kretprobes(&rp, 1);
1767}
1768EXPORT_SYMBOL_GPL(unregister_kretprobe);
1769
1770void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1771{
1772 int i;
1773
1774 if (num <= 0)
1775 return;
1776 mutex_lock(&kprobe_mutex);
1777 for (i = 0; i < num; i++)
1778 if (__unregister_kprobe_top(&rps[i]->kp) < 0)
1779 rps[i]->kp.addr = NULL;
1780 mutex_unlock(&kprobe_mutex);
1781
1782 synchronize_sched();
1783 for (i = 0; i < num; i++) {
1784 if (rps[i]->kp.addr) {
1785 __unregister_kprobe_bottom(&rps[i]->kp);
1786 cleanup_rp_inst(rps[i]);
1787 }
1788 }
1789}
1790EXPORT_SYMBOL_GPL(unregister_kretprobes);
1791
1792#else /* CONFIG_KRETPROBES */
1793int __kprobes register_kretprobe(struct kretprobe *rp)
1794{
1795 return -ENOSYS;
1796}
1797EXPORT_SYMBOL_GPL(register_kretprobe);
1798
1799int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1800{
1801 return -ENOSYS;
1802}
1803EXPORT_SYMBOL_GPL(register_kretprobes);
1804
1805void __kprobes unregister_kretprobe(struct kretprobe *rp)
1806{
1807}
1808EXPORT_SYMBOL_GPL(unregister_kretprobe);
1809
1810void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1811{
1812}
1813EXPORT_SYMBOL_GPL(unregister_kretprobes);
1814
1815static int __kprobes pre_handler_kretprobe(struct kprobe *p,
1816 struct pt_regs *regs)
1817{
1818 return 0;
1819}
1820
1821#endif /* CONFIG_KRETPROBES */
1822
1823/* Set the kprobe gone and remove its instruction buffer. */
1824static void __kprobes kill_kprobe(struct kprobe *p)
1825{
1826 struct kprobe *kp;
1827
1828 p->flags |= KPROBE_FLAG_GONE;
1829 if (kprobe_aggrprobe(p)) {
1830 /*
1831 * If this is an aggr_kprobe, we have to list all the
1832 * chained probes and mark them GONE.
1833 */
1834 list_for_each_entry_rcu(kp, &p->list, list)
1835 kp->flags |= KPROBE_FLAG_GONE;
1836 p->post_handler = NULL;
1837 p->break_handler = NULL;
1838 kill_optimized_kprobe(p);
1839 }
1840 /*
1841 * Here, we can remove insn_slot safely, because no thread calls
1842 * the original probed function (which will be freed soon) any more.
1843 */
1844 arch_remove_kprobe(p);
1845}
1846
1847/* Disable one kprobe */
1848int __kprobes disable_kprobe(struct kprobe *kp)
1849{
1850 int ret = 0;
1851
1852 mutex_lock(&kprobe_mutex);
1853
1854 /* Disable this kprobe */
1855 if (__disable_kprobe(kp) == NULL)
1856 ret = -EINVAL;
1857
1858 mutex_unlock(&kprobe_mutex);
1859 return ret;
1860}
1861EXPORT_SYMBOL_GPL(disable_kprobe);
1862
1863/* Enable one kprobe */
1864int __kprobes enable_kprobe(struct kprobe *kp)
1865{
1866 int ret = 0;
1867 struct kprobe *p;
1868
1869 mutex_lock(&kprobe_mutex);
1870
1871 /* Check whether specified probe is valid. */
1872 p = __get_valid_kprobe(kp);
1873 if (unlikely(p == NULL)) {
1874 ret = -EINVAL;
1875 goto out;
1876 }
1877
1878 if (kprobe_gone(kp)) {
1879 /* This kprobe has gone, we couldn't enable it. */
1880 ret = -EINVAL;
1881 goto out;
1882 }
1883
1884 if (p != kp)
1885 kp->flags &= ~KPROBE_FLAG_DISABLED;
1886
1887 if (!kprobes_all_disarmed && kprobe_disabled(p)) {
1888 p->flags &= ~KPROBE_FLAG_DISABLED;
1889 arm_kprobe(p);
1890 }
1891out:
1892 mutex_unlock(&kprobe_mutex);
1893 return ret;
1894}
1895EXPORT_SYMBOL_GPL(enable_kprobe);
1896
1897void __kprobes dump_kprobe(struct kprobe *kp)
1898{
1899 printk(KERN_WARNING "Dumping kprobe:\n");
1900 printk(KERN_WARNING "Name: %s\nAddress: %p\nOffset: %x\n",
1901 kp->symbol_name, kp->addr, kp->offset);
1902}
1903
1904/* Module notifier call back, checking kprobes on the module */
1905static int __kprobes kprobes_module_callback(struct notifier_block *nb,
1906 unsigned long val, void *data)
1907{
1908 struct module *mod = data;
1909 struct hlist_head *head;
1910 struct hlist_node *node;
1911 struct kprobe *p;
1912 unsigned int i;
1913 int checkcore = (val == MODULE_STATE_GOING);
1914
1915 if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
1916 return NOTIFY_DONE;
1917
1918 /*
1919 * When MODULE_STATE_GOING was notified, both of module .text and
1920 * .init.text sections would be freed. When MODULE_STATE_LIVE was
1921 * notified, only .init.text section would be freed. We need to
1922 * disable kprobes which have been inserted in the sections.
1923 */
1924 mutex_lock(&kprobe_mutex);
1925 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1926 head = &kprobe_table[i];
1927 hlist_for_each_entry_rcu(p, node, head, hlist)
1928 if (within_module_init((unsigned long)p->addr, mod) ||
1929 (checkcore &&
1930 within_module_core((unsigned long)p->addr, mod))) {
1931 /*
1932 * The vaddr this probe is installed will soon
1933 * be vfreed buy not synced to disk. Hence,
1934 * disarming the breakpoint isn't needed.
1935 */
1936 kill_kprobe(p);
1937 }
1938 }
1939 mutex_unlock(&kprobe_mutex);
1940 return NOTIFY_DONE;
1941}
1942
1943static struct notifier_block kprobe_module_nb = {
1944 .notifier_call = kprobes_module_callback,
1945 .priority = 0
1946};
1947
1948static int __init init_kprobes(void)
1949{
1950 int i, err = 0;
1951 unsigned long offset = 0, size = 0;
1952 char *modname, namebuf[128];
1953 const char *symbol_name;
1954 void *addr;
1955 struct kprobe_blackpoint *kb;
1956
1957 /* FIXME allocate the probe table, currently defined statically */
1958 /* initialize all list heads */
1959 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1960 INIT_HLIST_HEAD(&kprobe_table[i]);
1961 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
1962 spin_lock_init(&(kretprobe_table_locks[i].lock));
1963 }
1964
1965 /*
1966 * Lookup and populate the kprobe_blacklist.
1967 *
1968 * Unlike the kretprobe blacklist, we'll need to determine
1969 * the range of addresses that belong to the said functions,
1970 * since a kprobe need not necessarily be at the beginning
1971 * of a function.
1972 */
1973 for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
1974 kprobe_lookup_name(kb->name, addr);
1975 if (!addr)
1976 continue;
1977
1978 kb->start_addr = (unsigned long)addr;
1979 symbol_name = kallsyms_lookup(kb->start_addr,
1980 &size, &offset, &modname, namebuf);
1981 if (!symbol_name)
1982 kb->range = 0;
1983 else
1984 kb->range = size;
1985 }
1986
1987 if (kretprobe_blacklist_size) {
1988 /* lookup the function address from its name */
1989 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1990 kprobe_lookup_name(kretprobe_blacklist[i].name,
1991 kretprobe_blacklist[i].addr);
1992 if (!kretprobe_blacklist[i].addr)
1993 printk("kretprobe: lookup failed: %s\n",
1994 kretprobe_blacklist[i].name);
1995 }
1996 }
1997
1998#if defined(CONFIG_OPTPROBES)
1999#if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
2000 /* Init kprobe_optinsn_slots */
2001 kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
2002#endif
2003 /* By default, kprobes can be optimized */
2004 kprobes_allow_optimization = true;
2005#endif
2006
2007 /* By default, kprobes are armed */
2008 kprobes_all_disarmed = false;
2009
2010 err = arch_init_kprobes();
2011 if (!err)
2012 err = register_die_notifier(&kprobe_exceptions_nb);
2013 if (!err)
2014 err = register_module_notifier(&kprobe_module_nb);
2015
2016 kprobes_initialized = (err == 0);
2017
2018 if (!err)
2019 init_test_probes();
2020 return err;
2021}
2022
2023#ifdef CONFIG_DEBUG_FS
2024static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
2025 const char *sym, int offset, char *modname, struct kprobe *pp)
2026{
2027 char *kprobe_type;
2028
2029 if (p->pre_handler == pre_handler_kretprobe)
2030 kprobe_type = "r";
2031 else if (p->pre_handler == setjmp_pre_handler)
2032 kprobe_type = "j";
2033 else
2034 kprobe_type = "k";
2035
2036 if (sym)
2037 seq_printf(pi, "%p %s %s+0x%x %s ",
2038 p->addr, kprobe_type, sym, offset,
2039 (modname ? modname : " "));
2040 else
2041 seq_printf(pi, "%p %s %p ",
2042 p->addr, kprobe_type, p->addr);
2043
2044 if (!pp)
2045 pp = p;
2046 seq_printf(pi, "%s%s%s\n",
2047 (kprobe_gone(p) ? "[GONE]" : ""),
2048 ((kprobe_disabled(p) && !kprobe_gone(p)) ? "[DISABLED]" : ""),
2049 (kprobe_optimized(pp) ? "[OPTIMIZED]" : ""));
2050}
2051
2052static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
2053{
2054 return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
2055}
2056
2057static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
2058{
2059 (*pos)++;
2060 if (*pos >= KPROBE_TABLE_SIZE)
2061 return NULL;
2062 return pos;
2063}
2064
2065static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v)
2066{
2067 /* Nothing to do */
2068}
2069
2070static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v)
2071{
2072 struct hlist_head *head;
2073 struct hlist_node *node;
2074 struct kprobe *p, *kp;
2075 const char *sym = NULL;
2076 unsigned int i = *(loff_t *) v;
2077 unsigned long offset = 0;
2078 char *modname, namebuf[128];
2079
2080 head = &kprobe_table[i];
2081 preempt_disable();
2082 hlist_for_each_entry_rcu(p, node, head, hlist) {
2083 sym = kallsyms_lookup((unsigned long)p->addr, NULL,
2084 &offset, &modname, namebuf);
2085 if (kprobe_aggrprobe(p)) {
2086 list_for_each_entry_rcu(kp, &p->list, list)
2087 report_probe(pi, kp, sym, offset, modname, p);
2088 } else
2089 report_probe(pi, p, sym, offset, modname, NULL);
2090 }
2091 preempt_enable();
2092 return 0;
2093}
2094
2095static const struct seq_operations kprobes_seq_ops = {
2096 .start = kprobe_seq_start,
2097 .next = kprobe_seq_next,
2098 .stop = kprobe_seq_stop,
2099 .show = show_kprobe_addr
2100};
2101
2102static int __kprobes kprobes_open(struct inode *inode, struct file *filp)
2103{
2104 return seq_open(filp, &kprobes_seq_ops);
2105}
2106
2107static const struct file_operations debugfs_kprobes_operations = {
2108 .open = kprobes_open,
2109 .read = seq_read,
2110 .llseek = seq_lseek,
2111 .release = seq_release,
2112};
2113
2114static void __kprobes arm_all_kprobes(void)
2115{
2116 struct hlist_head *head;
2117 struct hlist_node *node;
2118 struct kprobe *p;
2119 unsigned int i;
2120
2121 mutex_lock(&kprobe_mutex);
2122
2123 /* If kprobes are armed, just return */
2124 if (!kprobes_all_disarmed)
2125 goto already_enabled;
2126
2127 /* Arming kprobes doesn't optimize kprobe itself */
2128 mutex_lock(&text_mutex);
2129 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2130 head = &kprobe_table[i];
2131 hlist_for_each_entry_rcu(p, node, head, hlist)
2132 if (!kprobe_disabled(p))
2133 __arm_kprobe(p);
2134 }
2135 mutex_unlock(&text_mutex);
2136
2137 kprobes_all_disarmed = false;
2138 printk(KERN_INFO "Kprobes globally enabled\n");
2139
2140already_enabled:
2141 mutex_unlock(&kprobe_mutex);
2142 return;
2143}
2144
2145static void __kprobes disarm_all_kprobes(void)
2146{
2147 struct hlist_head *head;
2148 struct hlist_node *node;
2149 struct kprobe *p;
2150 unsigned int i;
2151
2152 mutex_lock(&kprobe_mutex);
2153
2154 /* If kprobes are already disarmed, just return */
2155 if (kprobes_all_disarmed) {
2156 mutex_unlock(&kprobe_mutex);
2157 return;
2158 }
2159
2160 kprobes_all_disarmed = true;
2161 printk(KERN_INFO "Kprobes globally disabled\n");
2162
2163 mutex_lock(&text_mutex);
2164 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2165 head = &kprobe_table[i];
2166 hlist_for_each_entry_rcu(p, node, head, hlist) {
2167 if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
2168 __disarm_kprobe(p, false);
2169 }
2170 }
2171 mutex_unlock(&text_mutex);
2172 mutex_unlock(&kprobe_mutex);
2173
2174 /* Wait for disarming all kprobes by optimizer */
2175 wait_for_kprobe_optimizer();
2176}
2177
2178/*
2179 * XXX: The debugfs bool file interface doesn't allow for callbacks
2180 * when the bool state is switched. We can reuse that facility when
2181 * available
2182 */
2183static ssize_t read_enabled_file_bool(struct file *file,
2184 char __user *user_buf, size_t count, loff_t *ppos)
2185{
2186 char buf[3];
2187
2188 if (!kprobes_all_disarmed)
2189 buf[0] = '1';
2190 else
2191 buf[0] = '0';
2192 buf[1] = '\n';
2193 buf[2] = 0x00;
2194 return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
2195}
2196
2197static ssize_t write_enabled_file_bool(struct file *file,
2198 const char __user *user_buf, size_t count, loff_t *ppos)
2199{
2200 char buf[32];
2201 int buf_size;
2202
2203 buf_size = min(count, (sizeof(buf)-1));
2204 if (copy_from_user(buf, user_buf, buf_size))
2205 return -EFAULT;
2206
2207 switch (buf[0]) {
2208 case 'y':
2209 case 'Y':
2210 case '1':
2211 arm_all_kprobes();
2212 break;
2213 case 'n':
2214 case 'N':
2215 case '0':
2216 disarm_all_kprobes();
2217 break;
2218 }
2219
2220 return count;
2221}
2222
2223static const struct file_operations fops_kp = {
2224 .read = read_enabled_file_bool,
2225 .write = write_enabled_file_bool,
2226 .llseek = default_llseek,
2227};
2228
2229static int __kprobes debugfs_kprobe_init(void)
2230{
2231 struct dentry *dir, *file;
2232 unsigned int value = 1;
2233
2234 dir = debugfs_create_dir("kprobes", NULL);
2235 if (!dir)
2236 return -ENOMEM;
2237
2238 file = debugfs_create_file("list", 0444, dir, NULL,
2239 &debugfs_kprobes_operations);
2240 if (!file) {
2241 debugfs_remove(dir);
2242 return -ENOMEM;
2243 }
2244
2245 file = debugfs_create_file("enabled", 0600, dir,
2246 &value, &fops_kp);
2247 if (!file) {
2248 debugfs_remove(dir);
2249 return -ENOMEM;
2250 }
2251
2252 return 0;
2253}
2254
2255late_initcall(debugfs_kprobe_init);
2256#endif /* CONFIG_DEBUG_FS */
2257
2258module_init(init_kprobes);
2259
2260/* defined in arch/.../kernel/kprobes.c */
2261EXPORT_SYMBOL_GPL(jprobe_return);