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/kallsyms.h>
30#include <linux/freezer.h>
31#include <linux/seq_file.h>
32#include <linux/debugfs.h>
33#include <linux/sysctl.h>
34#include <linux/kdebug.h>
35#include <linux/memory.h>
36#include <linux/ftrace.h>
37#include <linux/cpu.h>
38#include <linux/jump_label.h>
39#include <linux/static_call.h>
40#include <linux/perf_event.h>
41#include <linux/execmem.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
98static int slots_per_page(struct kprobe_insn_cache *c)
99{
100 return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));
101}
102
103enum kprobe_slot_state {
104 SLOT_CLEAN = 0,
105 SLOT_DIRTY = 1,
106 SLOT_USED = 2,
107};
108
109void __weak *alloc_insn_page(void)
110{
111 /*
112 * Use execmem_alloc() so this page is within +/- 2GB of where the
113 * kernel image and loaded module images reside. This is required
114 * for most of the architectures.
115 * (e.g. x86-64 needs this to handle the %rip-relative fixups.)
116 */
117 return execmem_alloc(EXECMEM_KPROBES, PAGE_SIZE);
118}
119
120static void free_insn_page(void *page)
121{
122 execmem_free(page);
123}
124
125struct kprobe_insn_cache kprobe_insn_slots = {
126 .mutex = __MUTEX_INITIALIZER(kprobe_insn_slots.mutex),
127 .alloc = alloc_insn_page,
128 .free = free_insn_page,
129 .sym = KPROBE_INSN_PAGE_SYM,
130 .pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
131 .insn_size = MAX_INSN_SIZE,
132 .nr_garbage = 0,
133};
134static int collect_garbage_slots(struct kprobe_insn_cache *c);
135
136/**
137 * __get_insn_slot() - Find a slot on an executable page for an instruction.
138 * We allocate an executable page if there's no room on existing ones.
139 */
140kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c)
141{
142 struct kprobe_insn_page *kip;
143 kprobe_opcode_t *slot = NULL;
144
145 /* Since the slot array is not protected by rcu, we need a mutex */
146 mutex_lock(&c->mutex);
147 retry:
148 rcu_read_lock();
149 list_for_each_entry_rcu(kip, &c->pages, list) {
150 if (kip->nused < slots_per_page(c)) {
151 int i;
152
153 for (i = 0; i < slots_per_page(c); i++) {
154 if (kip->slot_used[i] == SLOT_CLEAN) {
155 kip->slot_used[i] = SLOT_USED;
156 kip->nused++;
157 slot = kip->insns + (i * c->insn_size);
158 rcu_read_unlock();
159 goto out;
160 }
161 }
162 /* kip->nused is broken. Fix it. */
163 kip->nused = slots_per_page(c);
164 WARN_ON(1);
165 }
166 }
167 rcu_read_unlock();
168
169 /* If there are any garbage slots, collect it and try again. */
170 if (c->nr_garbage && collect_garbage_slots(c) == 0)
171 goto retry;
172
173 /* All out of space. Need to allocate a new page. */
174 kip = kmalloc(struct_size(kip, slot_used, slots_per_page(c)), GFP_KERNEL);
175 if (!kip)
176 goto out;
177
178 kip->insns = c->alloc();
179 if (!kip->insns) {
180 kfree(kip);
181 goto out;
182 }
183 INIT_LIST_HEAD(&kip->list);
184 memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c));
185 kip->slot_used[0] = SLOT_USED;
186 kip->nused = 1;
187 kip->ngarbage = 0;
188 kip->cache = c;
189 list_add_rcu(&kip->list, &c->pages);
190 slot = kip->insns;
191
192 /* Record the perf ksymbol register event after adding the page */
193 perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL, (unsigned long)kip->insns,
194 PAGE_SIZE, false, c->sym);
195out:
196 mutex_unlock(&c->mutex);
197 return slot;
198}
199
200/* Return true if all garbages are collected, otherwise false. */
201static bool collect_one_slot(struct kprobe_insn_page *kip, int idx)
202{
203 kip->slot_used[idx] = SLOT_CLEAN;
204 kip->nused--;
205 if (kip->nused != 0)
206 return false;
207
208 /*
209 * Page is no longer in use. Free it unless
210 * it's the last one. We keep the last one
211 * so as not to have to set it up again the
212 * next time somebody inserts a probe.
213 */
214 if (!list_is_singular(&kip->list)) {
215 /*
216 * Record perf ksymbol unregister event before removing
217 * the page.
218 */
219 perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL,
220 (unsigned long)kip->insns, PAGE_SIZE, true,
221 kip->cache->sym);
222 list_del_rcu(&kip->list);
223 synchronize_rcu();
224 kip->cache->free(kip->insns);
225 kfree(kip);
226 }
227 return true;
228}
229
230static int collect_garbage_slots(struct kprobe_insn_cache *c)
231{
232 struct kprobe_insn_page *kip, *next;
233
234 /* Ensure no-one is interrupted on the garbages */
235 synchronize_rcu();
236
237 list_for_each_entry_safe(kip, next, &c->pages, list) {
238 int i;
239
240 if (kip->ngarbage == 0)
241 continue;
242 kip->ngarbage = 0; /* we will collect all garbages */
243 for (i = 0; i < slots_per_page(c); i++) {
244 if (kip->slot_used[i] == SLOT_DIRTY && collect_one_slot(kip, i))
245 break;
246 }
247 }
248 c->nr_garbage = 0;
249 return 0;
250}
251
252void __free_insn_slot(struct kprobe_insn_cache *c,
253 kprobe_opcode_t *slot, int dirty)
254{
255 struct kprobe_insn_page *kip;
256 long idx;
257
258 mutex_lock(&c->mutex);
259 rcu_read_lock();
260 list_for_each_entry_rcu(kip, &c->pages, list) {
261 idx = ((long)slot - (long)kip->insns) /
262 (c->insn_size * sizeof(kprobe_opcode_t));
263 if (idx >= 0 && idx < slots_per_page(c))
264 goto out;
265 }
266 /* Could not find this slot. */
267 WARN_ON(1);
268 kip = NULL;
269out:
270 rcu_read_unlock();
271 /* Mark and sweep: this may sleep */
272 if (kip) {
273 /* Check double free */
274 WARN_ON(kip->slot_used[idx] != SLOT_USED);
275 if (dirty) {
276 kip->slot_used[idx] = SLOT_DIRTY;
277 kip->ngarbage++;
278 if (++c->nr_garbage > slots_per_page(c))
279 collect_garbage_slots(c);
280 } else {
281 collect_one_slot(kip, idx);
282 }
283 }
284 mutex_unlock(&c->mutex);
285}
286
287/*
288 * Check given address is on the page of kprobe instruction slots.
289 * This will be used for checking whether the address on a stack
290 * is on a text area or not.
291 */
292bool __is_insn_slot_addr(struct kprobe_insn_cache *c, unsigned long addr)
293{
294 struct kprobe_insn_page *kip;
295 bool ret = false;
296
297 rcu_read_lock();
298 list_for_each_entry_rcu(kip, &c->pages, list) {
299 if (addr >= (unsigned long)kip->insns &&
300 addr < (unsigned long)kip->insns + PAGE_SIZE) {
301 ret = true;
302 break;
303 }
304 }
305 rcu_read_unlock();
306
307 return ret;
308}
309
310int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum,
311 unsigned long *value, char *type, char *sym)
312{
313 struct kprobe_insn_page *kip;
314 int ret = -ERANGE;
315
316 rcu_read_lock();
317 list_for_each_entry_rcu(kip, &c->pages, list) {
318 if ((*symnum)--)
319 continue;
320 strscpy(sym, c->sym, KSYM_NAME_LEN);
321 *type = 't';
322 *value = (unsigned long)kip->insns;
323 ret = 0;
324 break;
325 }
326 rcu_read_unlock();
327
328 return ret;
329}
330
331#ifdef CONFIG_OPTPROBES
332void __weak *alloc_optinsn_page(void)
333{
334 return alloc_insn_page();
335}
336
337void __weak free_optinsn_page(void *page)
338{
339 free_insn_page(page);
340}
341
342/* For optimized_kprobe buffer */
343struct kprobe_insn_cache kprobe_optinsn_slots = {
344 .mutex = __MUTEX_INITIALIZER(kprobe_optinsn_slots.mutex),
345 .alloc = alloc_optinsn_page,
346 .free = free_optinsn_page,
347 .sym = KPROBE_OPTINSN_PAGE_SYM,
348 .pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
349 /* .insn_size is initialized later */
350 .nr_garbage = 0,
351};
352#endif /* CONFIG_OPTPROBES */
353#endif /* __ARCH_WANT_KPROBES_INSN_SLOT */
354
355/* We have preemption disabled.. so it is safe to use __ versions */
356static inline void set_kprobe_instance(struct kprobe *kp)
357{
358 __this_cpu_write(kprobe_instance, kp);
359}
360
361static inline void reset_kprobe_instance(void)
362{
363 __this_cpu_write(kprobe_instance, NULL);
364}
365
366/*
367 * This routine is called either:
368 * - under the 'kprobe_mutex' - during kprobe_[un]register().
369 * OR
370 * - with preemption disabled - from architecture specific code.
371 */
372struct kprobe *get_kprobe(void *addr)
373{
374 struct hlist_head *head;
375 struct kprobe *p;
376
377 head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
378 hlist_for_each_entry_rcu(p, head, hlist,
379 lockdep_is_held(&kprobe_mutex)) {
380 if (p->addr == addr)
381 return p;
382 }
383
384 return NULL;
385}
386NOKPROBE_SYMBOL(get_kprobe);
387
388static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs);
389
390/* Return true if 'p' is an aggregator */
391static inline bool kprobe_aggrprobe(struct kprobe *p)
392{
393 return p->pre_handler == aggr_pre_handler;
394}
395
396/* Return true if 'p' is unused */
397static inline bool kprobe_unused(struct kprobe *p)
398{
399 return kprobe_aggrprobe(p) && kprobe_disabled(p) &&
400 list_empty(&p->list);
401}
402
403/* Keep all fields in the kprobe consistent. */
404static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p)
405{
406 memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t));
407 memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn));
408}
409
410#ifdef CONFIG_OPTPROBES
411/* NOTE: This is protected by 'kprobe_mutex'. */
412static bool kprobes_allow_optimization;
413
414/*
415 * Call all 'kprobe::pre_handler' on the list, but ignores its return value.
416 * This must be called from arch-dep optimized caller.
417 */
418void opt_pre_handler(struct kprobe *p, struct pt_regs *regs)
419{
420 struct kprobe *kp;
421
422 list_for_each_entry_rcu(kp, &p->list, list) {
423 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
424 set_kprobe_instance(kp);
425 kp->pre_handler(kp, regs);
426 }
427 reset_kprobe_instance();
428 }
429}
430NOKPROBE_SYMBOL(opt_pre_handler);
431
432/* Free optimized instructions and optimized_kprobe */
433static void free_aggr_kprobe(struct kprobe *p)
434{
435 struct optimized_kprobe *op;
436
437 op = container_of(p, struct optimized_kprobe, kp);
438 arch_remove_optimized_kprobe(op);
439 arch_remove_kprobe(p);
440 kfree(op);
441}
442
443/* Return true if the kprobe is ready for optimization. */
444static inline int kprobe_optready(struct kprobe *p)
445{
446 struct optimized_kprobe *op;
447
448 if (kprobe_aggrprobe(p)) {
449 op = container_of(p, struct optimized_kprobe, kp);
450 return arch_prepared_optinsn(&op->optinsn);
451 }
452
453 return 0;
454}
455
456/* Return true if the kprobe is disarmed. Note: p must be on hash list */
457bool kprobe_disarmed(struct kprobe *p)
458{
459 struct optimized_kprobe *op;
460
461 /* If kprobe is not aggr/opt probe, just return kprobe is disabled */
462 if (!kprobe_aggrprobe(p))
463 return kprobe_disabled(p);
464
465 op = container_of(p, struct optimized_kprobe, kp);
466
467 return kprobe_disabled(p) && list_empty(&op->list);
468}
469
470/* Return true if the probe is queued on (un)optimizing lists */
471static bool kprobe_queued(struct kprobe *p)
472{
473 struct optimized_kprobe *op;
474
475 if (kprobe_aggrprobe(p)) {
476 op = container_of(p, struct optimized_kprobe, kp);
477 if (!list_empty(&op->list))
478 return true;
479 }
480 return false;
481}
482
483/*
484 * Return an optimized kprobe whose optimizing code replaces
485 * instructions including 'addr' (exclude breakpoint).
486 */
487static struct kprobe *get_optimized_kprobe(kprobe_opcode_t *addr)
488{
489 int i;
490 struct kprobe *p = NULL;
491 struct optimized_kprobe *op;
492
493 /* Don't check i == 0, since that is a breakpoint case. */
494 for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH / sizeof(kprobe_opcode_t); i++)
495 p = get_kprobe(addr - i);
496
497 if (p && kprobe_optready(p)) {
498 op = container_of(p, struct optimized_kprobe, kp);
499 if (arch_within_optimized_kprobe(op, addr))
500 return p;
501 }
502
503 return NULL;
504}
505
506/* Optimization staging list, protected by 'kprobe_mutex' */
507static LIST_HEAD(optimizing_list);
508static LIST_HEAD(unoptimizing_list);
509static LIST_HEAD(freeing_list);
510
511static void kprobe_optimizer(struct work_struct *work);
512static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
513#define OPTIMIZE_DELAY 5
514
515/*
516 * Optimize (replace a breakpoint with a jump) kprobes listed on
517 * 'optimizing_list'.
518 */
519static void do_optimize_kprobes(void)
520{
521 lockdep_assert_held(&text_mutex);
522 /*
523 * The optimization/unoptimization refers 'online_cpus' via
524 * stop_machine() and cpu-hotplug modifies the 'online_cpus'.
525 * And same time, 'text_mutex' will be held in cpu-hotplug and here.
526 * This combination can cause a deadlock (cpu-hotplug tries to lock
527 * 'text_mutex' but stop_machine() can not be done because
528 * the 'online_cpus' has been changed)
529 * To avoid this deadlock, caller must have locked cpu-hotplug
530 * for preventing cpu-hotplug outside of 'text_mutex' locking.
531 */
532 lockdep_assert_cpus_held();
533
534 /* Optimization never be done when disarmed */
535 if (kprobes_all_disarmed || !kprobes_allow_optimization ||
536 list_empty(&optimizing_list))
537 return;
538
539 arch_optimize_kprobes(&optimizing_list);
540}
541
542/*
543 * Unoptimize (replace a jump with a breakpoint and remove the breakpoint
544 * if need) kprobes listed on 'unoptimizing_list'.
545 */
546static void do_unoptimize_kprobes(void)
547{
548 struct optimized_kprobe *op, *tmp;
549
550 lockdep_assert_held(&text_mutex);
551 /* See comment in do_optimize_kprobes() */
552 lockdep_assert_cpus_held();
553
554 if (!list_empty(&unoptimizing_list))
555 arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list);
556
557 /* Loop on 'freeing_list' for disarming and removing from kprobe hash list */
558 list_for_each_entry_safe(op, tmp, &freeing_list, list) {
559 /* Switching from detour code to origin */
560 op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
561 /* Disarm probes if marked disabled and not gone */
562 if (kprobe_disabled(&op->kp) && !kprobe_gone(&op->kp))
563 arch_disarm_kprobe(&op->kp);
564 if (kprobe_unused(&op->kp)) {
565 /*
566 * Remove unused probes from hash list. After waiting
567 * for synchronization, these probes are reclaimed.
568 * (reclaiming is done by do_free_cleaned_kprobes().)
569 */
570 hlist_del_rcu(&op->kp.hlist);
571 } else
572 list_del_init(&op->list);
573 }
574}
575
576/* Reclaim all kprobes on the 'freeing_list' */
577static void do_free_cleaned_kprobes(void)
578{
579 struct optimized_kprobe *op, *tmp;
580
581 list_for_each_entry_safe(op, tmp, &freeing_list, list) {
582 list_del_init(&op->list);
583 if (WARN_ON_ONCE(!kprobe_unused(&op->kp))) {
584 /*
585 * This must not happen, but if there is a kprobe
586 * still in use, keep it on kprobes hash list.
587 */
588 continue;
589 }
590 free_aggr_kprobe(&op->kp);
591 }
592}
593
594/* Start optimizer after OPTIMIZE_DELAY passed */
595static void kick_kprobe_optimizer(void)
596{
597 schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
598}
599
600/* Kprobe jump optimizer */
601static void kprobe_optimizer(struct work_struct *work)
602{
603 mutex_lock(&kprobe_mutex);
604 cpus_read_lock();
605 mutex_lock(&text_mutex);
606
607 /*
608 * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
609 * kprobes before waiting for quiesence period.
610 */
611 do_unoptimize_kprobes();
612
613 /*
614 * Step 2: Wait for quiesence period to ensure all potentially
615 * preempted tasks to have normally scheduled. Because optprobe
616 * may modify multiple instructions, there is a chance that Nth
617 * instruction is preempted. In that case, such tasks can return
618 * to 2nd-Nth byte of jump instruction. This wait is for avoiding it.
619 * Note that on non-preemptive kernel, this is transparently converted
620 * to synchronoze_sched() to wait for all interrupts to have completed.
621 */
622 synchronize_rcu_tasks();
623
624 /* Step 3: Optimize kprobes after quiesence period */
625 do_optimize_kprobes();
626
627 /* Step 4: Free cleaned kprobes after quiesence period */
628 do_free_cleaned_kprobes();
629
630 mutex_unlock(&text_mutex);
631 cpus_read_unlock();
632
633 /* Step 5: Kick optimizer again if needed */
634 if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
635 kick_kprobe_optimizer();
636
637 mutex_unlock(&kprobe_mutex);
638}
639
640/* Wait for completing optimization and unoptimization */
641void wait_for_kprobe_optimizer(void)
642{
643 mutex_lock(&kprobe_mutex);
644
645 while (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) {
646 mutex_unlock(&kprobe_mutex);
647
648 /* This will also make 'optimizing_work' execute immmediately */
649 flush_delayed_work(&optimizing_work);
650 /* 'optimizing_work' might not have been queued yet, relax */
651 cpu_relax();
652
653 mutex_lock(&kprobe_mutex);
654 }
655
656 mutex_unlock(&kprobe_mutex);
657}
658
659bool optprobe_queued_unopt(struct optimized_kprobe *op)
660{
661 struct optimized_kprobe *_op;
662
663 list_for_each_entry(_op, &unoptimizing_list, list) {
664 if (op == _op)
665 return true;
666 }
667
668 return false;
669}
670
671/* Optimize kprobe if p is ready to be optimized */
672static void optimize_kprobe(struct kprobe *p)
673{
674 struct optimized_kprobe *op;
675
676 /* Check if the kprobe is disabled or not ready for optimization. */
677 if (!kprobe_optready(p) || !kprobes_allow_optimization ||
678 (kprobe_disabled(p) || kprobes_all_disarmed))
679 return;
680
681 /* kprobes with 'post_handler' can not be optimized */
682 if (p->post_handler)
683 return;
684
685 op = container_of(p, struct optimized_kprobe, kp);
686
687 /* Check there is no other kprobes at the optimized instructions */
688 if (arch_check_optimized_kprobe(op) < 0)
689 return;
690
691 /* Check if it is already optimized. */
692 if (op->kp.flags & KPROBE_FLAG_OPTIMIZED) {
693 if (optprobe_queued_unopt(op)) {
694 /* This is under unoptimizing. Just dequeue the probe */
695 list_del_init(&op->list);
696 }
697 return;
698 }
699 op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
700
701 /*
702 * On the 'unoptimizing_list' and 'optimizing_list',
703 * 'op' must have OPTIMIZED flag
704 */
705 if (WARN_ON_ONCE(!list_empty(&op->list)))
706 return;
707
708 list_add(&op->list, &optimizing_list);
709 kick_kprobe_optimizer();
710}
711
712/* Short cut to direct unoptimizing */
713static void force_unoptimize_kprobe(struct optimized_kprobe *op)
714{
715 lockdep_assert_cpus_held();
716 arch_unoptimize_kprobe(op);
717 op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
718}
719
720/* Unoptimize a kprobe if p is optimized */
721static void unoptimize_kprobe(struct kprobe *p, bool force)
722{
723 struct optimized_kprobe *op;
724
725 if (!kprobe_aggrprobe(p) || kprobe_disarmed(p))
726 return; /* This is not an optprobe nor optimized */
727
728 op = container_of(p, struct optimized_kprobe, kp);
729 if (!kprobe_optimized(p))
730 return;
731
732 if (!list_empty(&op->list)) {
733 if (optprobe_queued_unopt(op)) {
734 /* Queued in unoptimizing queue */
735 if (force) {
736 /*
737 * Forcibly unoptimize the kprobe here, and queue it
738 * in the freeing list for release afterwards.
739 */
740 force_unoptimize_kprobe(op);
741 list_move(&op->list, &freeing_list);
742 }
743 } else {
744 /* Dequeue from the optimizing queue */
745 list_del_init(&op->list);
746 op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
747 }
748 return;
749 }
750
751 /* Optimized kprobe case */
752 if (force) {
753 /* Forcibly update the code: this is a special case */
754 force_unoptimize_kprobe(op);
755 } else {
756 list_add(&op->list, &unoptimizing_list);
757 kick_kprobe_optimizer();
758 }
759}
760
761/* Cancel unoptimizing for reusing */
762static int reuse_unused_kprobe(struct kprobe *ap)
763{
764 struct optimized_kprobe *op;
765
766 /*
767 * Unused kprobe MUST be on the way of delayed unoptimizing (means
768 * there is still a relative jump) and disabled.
769 */
770 op = container_of(ap, struct optimized_kprobe, kp);
771 WARN_ON_ONCE(list_empty(&op->list));
772 /* Enable the probe again */
773 ap->flags &= ~KPROBE_FLAG_DISABLED;
774 /* Optimize it again. (remove from 'op->list') */
775 if (!kprobe_optready(ap))
776 return -EINVAL;
777
778 optimize_kprobe(ap);
779 return 0;
780}
781
782/* Remove optimized instructions */
783static void kill_optimized_kprobe(struct kprobe *p)
784{
785 struct optimized_kprobe *op;
786
787 op = container_of(p, struct optimized_kprobe, kp);
788 if (!list_empty(&op->list))
789 /* Dequeue from the (un)optimization queue */
790 list_del_init(&op->list);
791 op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
792
793 if (kprobe_unused(p)) {
794 /*
795 * Unused kprobe is on unoptimizing or freeing list. We move it
796 * to freeing_list and let the kprobe_optimizer() remove it from
797 * the kprobe hash list and free it.
798 */
799 if (optprobe_queued_unopt(op))
800 list_move(&op->list, &freeing_list);
801 }
802
803 /* Don't touch the code, because it is already freed. */
804 arch_remove_optimized_kprobe(op);
805}
806
807static inline
808void __prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
809{
810 if (!kprobe_ftrace(p))
811 arch_prepare_optimized_kprobe(op, p);
812}
813
814/* Try to prepare optimized instructions */
815static void prepare_optimized_kprobe(struct kprobe *p)
816{
817 struct optimized_kprobe *op;
818
819 op = container_of(p, struct optimized_kprobe, kp);
820 __prepare_optimized_kprobe(op, p);
821}
822
823/* Allocate new optimized_kprobe and try to prepare optimized instructions. */
824static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
825{
826 struct optimized_kprobe *op;
827
828 op = kzalloc(sizeof(struct optimized_kprobe), GFP_KERNEL);
829 if (!op)
830 return NULL;
831
832 INIT_LIST_HEAD(&op->list);
833 op->kp.addr = p->addr;
834 __prepare_optimized_kprobe(op, p);
835
836 return &op->kp;
837}
838
839static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p);
840
841/*
842 * Prepare an optimized_kprobe and optimize it.
843 * NOTE: 'p' must be a normal registered kprobe.
844 */
845static void try_to_optimize_kprobe(struct kprobe *p)
846{
847 struct kprobe *ap;
848 struct optimized_kprobe *op;
849
850 /* Impossible to optimize ftrace-based kprobe. */
851 if (kprobe_ftrace(p))
852 return;
853
854 /* For preparing optimization, jump_label_text_reserved() is called. */
855 cpus_read_lock();
856 jump_label_lock();
857 mutex_lock(&text_mutex);
858
859 ap = alloc_aggr_kprobe(p);
860 if (!ap)
861 goto out;
862
863 op = container_of(ap, struct optimized_kprobe, kp);
864 if (!arch_prepared_optinsn(&op->optinsn)) {
865 /* If failed to setup optimizing, fallback to kprobe. */
866 arch_remove_optimized_kprobe(op);
867 kfree(op);
868 goto out;
869 }
870
871 init_aggr_kprobe(ap, p);
872 optimize_kprobe(ap); /* This just kicks optimizer thread. */
873
874out:
875 mutex_unlock(&text_mutex);
876 jump_label_unlock();
877 cpus_read_unlock();
878}
879
880static void optimize_all_kprobes(void)
881{
882 struct hlist_head *head;
883 struct kprobe *p;
884 unsigned int i;
885
886 mutex_lock(&kprobe_mutex);
887 /* If optimization is already allowed, just return. */
888 if (kprobes_allow_optimization)
889 goto out;
890
891 cpus_read_lock();
892 kprobes_allow_optimization = true;
893 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
894 head = &kprobe_table[i];
895 hlist_for_each_entry(p, head, hlist)
896 if (!kprobe_disabled(p))
897 optimize_kprobe(p);
898 }
899 cpus_read_unlock();
900 pr_info("kprobe jump-optimization is enabled. All kprobes are optimized if possible.\n");
901out:
902 mutex_unlock(&kprobe_mutex);
903}
904
905#ifdef CONFIG_SYSCTL
906static void unoptimize_all_kprobes(void)
907{
908 struct hlist_head *head;
909 struct kprobe *p;
910 unsigned int i;
911
912 mutex_lock(&kprobe_mutex);
913 /* If optimization is already prohibited, just return. */
914 if (!kprobes_allow_optimization) {
915 mutex_unlock(&kprobe_mutex);
916 return;
917 }
918
919 cpus_read_lock();
920 kprobes_allow_optimization = false;
921 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
922 head = &kprobe_table[i];
923 hlist_for_each_entry(p, head, hlist) {
924 if (!kprobe_disabled(p))
925 unoptimize_kprobe(p, false);
926 }
927 }
928 cpus_read_unlock();
929 mutex_unlock(&kprobe_mutex);
930
931 /* Wait for unoptimizing completion. */
932 wait_for_kprobe_optimizer();
933 pr_info("kprobe jump-optimization is disabled. All kprobes are based on software breakpoint.\n");
934}
935
936static DEFINE_MUTEX(kprobe_sysctl_mutex);
937static int sysctl_kprobes_optimization;
938static int proc_kprobes_optimization_handler(const struct ctl_table *table,
939 int write, void *buffer,
940 size_t *length, loff_t *ppos)
941{
942 int ret;
943
944 mutex_lock(&kprobe_sysctl_mutex);
945 sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0;
946 ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
947
948 if (sysctl_kprobes_optimization)
949 optimize_all_kprobes();
950 else
951 unoptimize_all_kprobes();
952 mutex_unlock(&kprobe_sysctl_mutex);
953
954 return ret;
955}
956
957static struct ctl_table kprobe_sysctls[] = {
958 {
959 .procname = "kprobes-optimization",
960 .data = &sysctl_kprobes_optimization,
961 .maxlen = sizeof(int),
962 .mode = 0644,
963 .proc_handler = proc_kprobes_optimization_handler,
964 .extra1 = SYSCTL_ZERO,
965 .extra2 = SYSCTL_ONE,
966 },
967};
968
969static void __init kprobe_sysctls_init(void)
970{
971 register_sysctl_init("debug", kprobe_sysctls);
972}
973#endif /* CONFIG_SYSCTL */
974
975/* Put a breakpoint for a probe. */
976static void __arm_kprobe(struct kprobe *p)
977{
978 struct kprobe *_p;
979
980 lockdep_assert_held(&text_mutex);
981
982 /* Find the overlapping optimized kprobes. */
983 _p = get_optimized_kprobe(p->addr);
984 if (unlikely(_p))
985 /* Fallback to unoptimized kprobe */
986 unoptimize_kprobe(_p, true);
987
988 arch_arm_kprobe(p);
989 optimize_kprobe(p); /* Try to optimize (add kprobe to a list) */
990}
991
992/* Remove the breakpoint of a probe. */
993static void __disarm_kprobe(struct kprobe *p, bool reopt)
994{
995 struct kprobe *_p;
996
997 lockdep_assert_held(&text_mutex);
998
999 /* Try to unoptimize */
1000 unoptimize_kprobe(p, kprobes_all_disarmed);
1001
1002 if (!kprobe_queued(p)) {
1003 arch_disarm_kprobe(p);
1004 /* If another kprobe was blocked, re-optimize it. */
1005 _p = get_optimized_kprobe(p->addr);
1006 if (unlikely(_p) && reopt)
1007 optimize_kprobe(_p);
1008 }
1009 /*
1010 * TODO: Since unoptimization and real disarming will be done by
1011 * the worker thread, we can not check whether another probe are
1012 * unoptimized because of this probe here. It should be re-optimized
1013 * by the worker thread.
1014 */
1015}
1016
1017#else /* !CONFIG_OPTPROBES */
1018
1019#define optimize_kprobe(p) do {} while (0)
1020#define unoptimize_kprobe(p, f) do {} while (0)
1021#define kill_optimized_kprobe(p) do {} while (0)
1022#define prepare_optimized_kprobe(p) do {} while (0)
1023#define try_to_optimize_kprobe(p) do {} while (0)
1024#define __arm_kprobe(p) arch_arm_kprobe(p)
1025#define __disarm_kprobe(p, o) arch_disarm_kprobe(p)
1026#define kprobe_disarmed(p) kprobe_disabled(p)
1027#define wait_for_kprobe_optimizer() do {} while (0)
1028
1029static int reuse_unused_kprobe(struct kprobe *ap)
1030{
1031 /*
1032 * If the optimized kprobe is NOT supported, the aggr kprobe is
1033 * released at the same time that the last aggregated kprobe is
1034 * unregistered.
1035 * Thus there should be no chance to reuse unused kprobe.
1036 */
1037 WARN_ON_ONCE(1);
1038 return -EINVAL;
1039}
1040
1041static void free_aggr_kprobe(struct kprobe *p)
1042{
1043 arch_remove_kprobe(p);
1044 kfree(p);
1045}
1046
1047static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
1048{
1049 return kzalloc(sizeof(struct kprobe), GFP_KERNEL);
1050}
1051#endif /* CONFIG_OPTPROBES */
1052
1053#ifdef CONFIG_KPROBES_ON_FTRACE
1054static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
1055 .func = kprobe_ftrace_handler,
1056 .flags = FTRACE_OPS_FL_SAVE_REGS,
1057};
1058
1059static struct ftrace_ops kprobe_ipmodify_ops __read_mostly = {
1060 .func = kprobe_ftrace_handler,
1061 .flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_IPMODIFY,
1062};
1063
1064static int kprobe_ipmodify_enabled;
1065static int kprobe_ftrace_enabled;
1066bool kprobe_ftrace_disabled;
1067
1068static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
1069 int *cnt)
1070{
1071 int ret;
1072
1073 lockdep_assert_held(&kprobe_mutex);
1074
1075 ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 0, 0);
1076 if (WARN_ONCE(ret < 0, "Failed to arm kprobe-ftrace at %pS (error %d)\n", p->addr, ret))
1077 return ret;
1078
1079 if (*cnt == 0) {
1080 ret = register_ftrace_function(ops);
1081 if (WARN(ret < 0, "Failed to register kprobe-ftrace (error %d)\n", ret))
1082 goto err_ftrace;
1083 }
1084
1085 (*cnt)++;
1086 return ret;
1087
1088err_ftrace:
1089 /*
1090 * At this point, sinec ops is not registered, we should be sefe from
1091 * registering empty filter.
1092 */
1093 ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0);
1094 return ret;
1095}
1096
1097static int arm_kprobe_ftrace(struct kprobe *p)
1098{
1099 bool ipmodify = (p->post_handler != NULL);
1100
1101 return __arm_kprobe_ftrace(p,
1102 ipmodify ? &kprobe_ipmodify_ops : &kprobe_ftrace_ops,
1103 ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);
1104}
1105
1106static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
1107 int *cnt)
1108{
1109 int ret;
1110
1111 lockdep_assert_held(&kprobe_mutex);
1112
1113 if (*cnt == 1) {
1114 ret = unregister_ftrace_function(ops);
1115 if (WARN(ret < 0, "Failed to unregister kprobe-ftrace (error %d)\n", ret))
1116 return ret;
1117 }
1118
1119 (*cnt)--;
1120
1121 ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0);
1122 WARN_ONCE(ret < 0, "Failed to disarm kprobe-ftrace at %pS (error %d)\n",
1123 p->addr, ret);
1124 return ret;
1125}
1126
1127static int disarm_kprobe_ftrace(struct kprobe *p)
1128{
1129 bool ipmodify = (p->post_handler != NULL);
1130
1131 return __disarm_kprobe_ftrace(p,
1132 ipmodify ? &kprobe_ipmodify_ops : &kprobe_ftrace_ops,
1133 ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);
1134}
1135
1136void kprobe_ftrace_kill(void)
1137{
1138 kprobe_ftrace_disabled = true;
1139}
1140#else /* !CONFIG_KPROBES_ON_FTRACE */
1141static inline int arm_kprobe_ftrace(struct kprobe *p)
1142{
1143 return -ENODEV;
1144}
1145
1146static inline int disarm_kprobe_ftrace(struct kprobe *p)
1147{
1148 return -ENODEV;
1149}
1150#endif
1151
1152static int prepare_kprobe(struct kprobe *p)
1153{
1154 /* Must ensure p->addr is really on ftrace */
1155 if (kprobe_ftrace(p))
1156 return arch_prepare_kprobe_ftrace(p);
1157
1158 return arch_prepare_kprobe(p);
1159}
1160
1161static int arm_kprobe(struct kprobe *kp)
1162{
1163 if (unlikely(kprobe_ftrace(kp)))
1164 return arm_kprobe_ftrace(kp);
1165
1166 cpus_read_lock();
1167 mutex_lock(&text_mutex);
1168 __arm_kprobe(kp);
1169 mutex_unlock(&text_mutex);
1170 cpus_read_unlock();
1171
1172 return 0;
1173}
1174
1175static int disarm_kprobe(struct kprobe *kp, bool reopt)
1176{
1177 if (unlikely(kprobe_ftrace(kp)))
1178 return disarm_kprobe_ftrace(kp);
1179
1180 cpus_read_lock();
1181 mutex_lock(&text_mutex);
1182 __disarm_kprobe(kp, reopt);
1183 mutex_unlock(&text_mutex);
1184 cpus_read_unlock();
1185
1186 return 0;
1187}
1188
1189/*
1190 * Aggregate handlers for multiple kprobes support - these handlers
1191 * take care of invoking the individual kprobe handlers on p->list
1192 */
1193static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
1194{
1195 struct kprobe *kp;
1196
1197 list_for_each_entry_rcu(kp, &p->list, list) {
1198 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
1199 set_kprobe_instance(kp);
1200 if (kp->pre_handler(kp, regs))
1201 return 1;
1202 }
1203 reset_kprobe_instance();
1204 }
1205 return 0;
1206}
1207NOKPROBE_SYMBOL(aggr_pre_handler);
1208
1209static void aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
1210 unsigned long flags)
1211{
1212 struct kprobe *kp;
1213
1214 list_for_each_entry_rcu(kp, &p->list, list) {
1215 if (kp->post_handler && likely(!kprobe_disabled(kp))) {
1216 set_kprobe_instance(kp);
1217 kp->post_handler(kp, regs, flags);
1218 reset_kprobe_instance();
1219 }
1220 }
1221}
1222NOKPROBE_SYMBOL(aggr_post_handler);
1223
1224/* Walks the list and increments 'nmissed' if 'p' has child probes. */
1225void kprobes_inc_nmissed_count(struct kprobe *p)
1226{
1227 struct kprobe *kp;
1228
1229 if (!kprobe_aggrprobe(p)) {
1230 p->nmissed++;
1231 } else {
1232 list_for_each_entry_rcu(kp, &p->list, list)
1233 kp->nmissed++;
1234 }
1235}
1236NOKPROBE_SYMBOL(kprobes_inc_nmissed_count);
1237
1238static struct kprobe kprobe_busy = {
1239 .addr = (void *) get_kprobe,
1240};
1241
1242void kprobe_busy_begin(void)
1243{
1244 struct kprobe_ctlblk *kcb;
1245
1246 preempt_disable();
1247 __this_cpu_write(current_kprobe, &kprobe_busy);
1248 kcb = get_kprobe_ctlblk();
1249 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
1250}
1251
1252void kprobe_busy_end(void)
1253{
1254 __this_cpu_write(current_kprobe, NULL);
1255 preempt_enable();
1256}
1257
1258/* Add the new probe to 'ap->list'. */
1259static int add_new_kprobe(struct kprobe *ap, struct kprobe *p)
1260{
1261 if (p->post_handler)
1262 unoptimize_kprobe(ap, true); /* Fall back to normal kprobe */
1263
1264 list_add_rcu(&p->list, &ap->list);
1265 if (p->post_handler && !ap->post_handler)
1266 ap->post_handler = aggr_post_handler;
1267
1268 return 0;
1269}
1270
1271/*
1272 * Fill in the required fields of the aggregator kprobe. Replace the
1273 * earlier kprobe in the hlist with the aggregator kprobe.
1274 */
1275static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
1276{
1277 /* Copy the insn slot of 'p' to 'ap'. */
1278 copy_kprobe(p, ap);
1279 flush_insn_slot(ap);
1280 ap->addr = p->addr;
1281 ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED;
1282 ap->pre_handler = aggr_pre_handler;
1283 /* We don't care the kprobe which has gone. */
1284 if (p->post_handler && !kprobe_gone(p))
1285 ap->post_handler = aggr_post_handler;
1286
1287 INIT_LIST_HEAD(&ap->list);
1288 INIT_HLIST_NODE(&ap->hlist);
1289
1290 list_add_rcu(&p->list, &ap->list);
1291 hlist_replace_rcu(&p->hlist, &ap->hlist);
1292}
1293
1294/*
1295 * This registers the second or subsequent kprobe at the same address.
1296 */
1297static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p)
1298{
1299 int ret = 0;
1300 struct kprobe *ap = orig_p;
1301
1302 cpus_read_lock();
1303
1304 /* For preparing optimization, jump_label_text_reserved() is called */
1305 jump_label_lock();
1306 mutex_lock(&text_mutex);
1307
1308 if (!kprobe_aggrprobe(orig_p)) {
1309 /* If 'orig_p' is not an 'aggr_kprobe', create new one. */
1310 ap = alloc_aggr_kprobe(orig_p);
1311 if (!ap) {
1312 ret = -ENOMEM;
1313 goto out;
1314 }
1315 init_aggr_kprobe(ap, orig_p);
1316 } else if (kprobe_unused(ap)) {
1317 /* This probe is going to die. Rescue it */
1318 ret = reuse_unused_kprobe(ap);
1319 if (ret)
1320 goto out;
1321 }
1322
1323 if (kprobe_gone(ap)) {
1324 /*
1325 * Attempting to insert new probe at the same location that
1326 * had a probe in the module vaddr area which already
1327 * freed. So, the instruction slot has already been
1328 * released. We need a new slot for the new probe.
1329 */
1330 ret = arch_prepare_kprobe(ap);
1331 if (ret)
1332 /*
1333 * Even if fail to allocate new slot, don't need to
1334 * free the 'ap'. It will be used next time, or
1335 * freed by unregister_kprobe().
1336 */
1337 goto out;
1338
1339 /* Prepare optimized instructions if possible. */
1340 prepare_optimized_kprobe(ap);
1341
1342 /*
1343 * Clear gone flag to prevent allocating new slot again, and
1344 * set disabled flag because it is not armed yet.
1345 */
1346 ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
1347 | KPROBE_FLAG_DISABLED;
1348 }
1349
1350 /* Copy the insn slot of 'p' to 'ap'. */
1351 copy_kprobe(ap, p);
1352 ret = add_new_kprobe(ap, p);
1353
1354out:
1355 mutex_unlock(&text_mutex);
1356 jump_label_unlock();
1357 cpus_read_unlock();
1358
1359 if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) {
1360 ap->flags &= ~KPROBE_FLAG_DISABLED;
1361 if (!kprobes_all_disarmed) {
1362 /* Arm the breakpoint again. */
1363 ret = arm_kprobe(ap);
1364 if (ret) {
1365 ap->flags |= KPROBE_FLAG_DISABLED;
1366 list_del_rcu(&p->list);
1367 synchronize_rcu();
1368 }
1369 }
1370 }
1371 return ret;
1372}
1373
1374bool __weak arch_within_kprobe_blacklist(unsigned long addr)
1375{
1376 /* The '__kprobes' functions and entry code must not be probed. */
1377 return addr >= (unsigned long)__kprobes_text_start &&
1378 addr < (unsigned long)__kprobes_text_end;
1379}
1380
1381static bool __within_kprobe_blacklist(unsigned long addr)
1382{
1383 struct kprobe_blacklist_entry *ent;
1384
1385 if (arch_within_kprobe_blacklist(addr))
1386 return true;
1387 /*
1388 * If 'kprobe_blacklist' is defined, check the address and
1389 * reject any probe registration in the prohibited area.
1390 */
1391 list_for_each_entry(ent, &kprobe_blacklist, list) {
1392 if (addr >= ent->start_addr && addr < ent->end_addr)
1393 return true;
1394 }
1395 return false;
1396}
1397
1398bool within_kprobe_blacklist(unsigned long addr)
1399{
1400 char symname[KSYM_NAME_LEN], *p;
1401
1402 if (__within_kprobe_blacklist(addr))
1403 return true;
1404
1405 /* Check if the address is on a suffixed-symbol */
1406 if (!lookup_symbol_name(addr, symname)) {
1407 p = strchr(symname, '.');
1408 if (!p)
1409 return false;
1410 *p = '\0';
1411 addr = (unsigned long)kprobe_lookup_name(symname, 0);
1412 if (addr)
1413 return __within_kprobe_blacklist(addr);
1414 }
1415 return false;
1416}
1417
1418/*
1419 * arch_adjust_kprobe_addr - adjust the address
1420 * @addr: symbol base address
1421 * @offset: offset within the symbol
1422 * @on_func_entry: was this @addr+@offset on the function entry
1423 *
1424 * Typically returns @addr + @offset, except for special cases where the
1425 * function might be prefixed by a CFI landing pad, in that case any offset
1426 * inside the landing pad is mapped to the first 'real' instruction of the
1427 * symbol.
1428 *
1429 * Specifically, for things like IBT/BTI, skip the resp. ENDBR/BTI.C
1430 * instruction at +0.
1431 */
1432kprobe_opcode_t *__weak arch_adjust_kprobe_addr(unsigned long addr,
1433 unsigned long offset,
1434 bool *on_func_entry)
1435{
1436 *on_func_entry = !offset;
1437 return (kprobe_opcode_t *)(addr + offset);
1438}
1439
1440/*
1441 * If 'symbol_name' is specified, look it up and add the 'offset'
1442 * to it. This way, we can specify a relative address to a symbol.
1443 * This returns encoded errors if it fails to look up symbol or invalid
1444 * combination of parameters.
1445 */
1446static kprobe_opcode_t *
1447_kprobe_addr(kprobe_opcode_t *addr, const char *symbol_name,
1448 unsigned long offset, bool *on_func_entry)
1449{
1450 if ((symbol_name && addr) || (!symbol_name && !addr))
1451 goto invalid;
1452
1453 if (symbol_name) {
1454 /*
1455 * Input: @sym + @offset
1456 * Output: @addr + @offset
1457 *
1458 * NOTE: kprobe_lookup_name() does *NOT* fold the offset
1459 * argument into it's output!
1460 */
1461 addr = kprobe_lookup_name(symbol_name, offset);
1462 if (!addr)
1463 return ERR_PTR(-ENOENT);
1464 }
1465
1466 /*
1467 * So here we have @addr + @offset, displace it into a new
1468 * @addr' + @offset' where @addr' is the symbol start address.
1469 */
1470 addr = (void *)addr + offset;
1471 if (!kallsyms_lookup_size_offset((unsigned long)addr, NULL, &offset))
1472 return ERR_PTR(-ENOENT);
1473 addr = (void *)addr - offset;
1474
1475 /*
1476 * Then ask the architecture to re-combine them, taking care of
1477 * magical function entry details while telling us if this was indeed
1478 * at the start of the function.
1479 */
1480 addr = arch_adjust_kprobe_addr((unsigned long)addr, offset, on_func_entry);
1481 if (addr)
1482 return addr;
1483
1484invalid:
1485 return ERR_PTR(-EINVAL);
1486}
1487
1488static kprobe_opcode_t *kprobe_addr(struct kprobe *p)
1489{
1490 bool on_func_entry;
1491 return _kprobe_addr(p->addr, p->symbol_name, p->offset, &on_func_entry);
1492}
1493
1494/*
1495 * Check the 'p' is valid and return the aggregator kprobe
1496 * at the same address.
1497 */
1498static struct kprobe *__get_valid_kprobe(struct kprobe *p)
1499{
1500 struct kprobe *ap, *list_p;
1501
1502 lockdep_assert_held(&kprobe_mutex);
1503
1504 ap = get_kprobe(p->addr);
1505 if (unlikely(!ap))
1506 return NULL;
1507
1508 if (p != ap) {
1509 list_for_each_entry(list_p, &ap->list, list)
1510 if (list_p == p)
1511 /* kprobe p is a valid probe */
1512 goto valid;
1513 return NULL;
1514 }
1515valid:
1516 return ap;
1517}
1518
1519/*
1520 * Warn and return error if the kprobe is being re-registered since
1521 * there must be a software bug.
1522 */
1523static inline int warn_kprobe_rereg(struct kprobe *p)
1524{
1525 int ret = 0;
1526
1527 mutex_lock(&kprobe_mutex);
1528 if (WARN_ON_ONCE(__get_valid_kprobe(p)))
1529 ret = -EINVAL;
1530 mutex_unlock(&kprobe_mutex);
1531
1532 return ret;
1533}
1534
1535static int check_ftrace_location(struct kprobe *p)
1536{
1537 unsigned long addr = (unsigned long)p->addr;
1538
1539 if (ftrace_location(addr) == addr) {
1540#ifdef CONFIG_KPROBES_ON_FTRACE
1541 p->flags |= KPROBE_FLAG_FTRACE;
1542#else
1543 return -EINVAL;
1544#endif
1545 }
1546 return 0;
1547}
1548
1549static bool is_cfi_preamble_symbol(unsigned long addr)
1550{
1551 char symbuf[KSYM_NAME_LEN];
1552
1553 if (lookup_symbol_name(addr, symbuf))
1554 return false;
1555
1556 return str_has_prefix(symbuf, "__cfi_") ||
1557 str_has_prefix(symbuf, "__pfx_");
1558}
1559
1560static int check_kprobe_address_safe(struct kprobe *p,
1561 struct module **probed_mod)
1562{
1563 int ret;
1564
1565 ret = check_ftrace_location(p);
1566 if (ret)
1567 return ret;
1568 jump_label_lock();
1569 preempt_disable();
1570
1571 /* Ensure the address is in a text area, and find a module if exists. */
1572 *probed_mod = NULL;
1573 if (!core_kernel_text((unsigned long) p->addr)) {
1574 *probed_mod = __module_text_address((unsigned long) p->addr);
1575 if (!(*probed_mod)) {
1576 ret = -EINVAL;
1577 goto out;
1578 }
1579 }
1580 /* Ensure it is not in reserved area. */
1581 if (in_gate_area_no_mm((unsigned long) p->addr) ||
1582 within_kprobe_blacklist((unsigned long) p->addr) ||
1583 jump_label_text_reserved(p->addr, p->addr) ||
1584 static_call_text_reserved(p->addr, p->addr) ||
1585 find_bug((unsigned long)p->addr) ||
1586 is_cfi_preamble_symbol((unsigned long)p->addr)) {
1587 ret = -EINVAL;
1588 goto out;
1589 }
1590
1591 /* Get module refcount and reject __init functions for loaded modules. */
1592 if (IS_ENABLED(CONFIG_MODULES) && *probed_mod) {
1593 /*
1594 * We must hold a refcount of the probed module while updating
1595 * its code to prohibit unexpected unloading.
1596 */
1597 if (unlikely(!try_module_get(*probed_mod))) {
1598 ret = -ENOENT;
1599 goto out;
1600 }
1601
1602 /*
1603 * If the module freed '.init.text', we couldn't insert
1604 * kprobes in there.
1605 */
1606 if (within_module_init((unsigned long)p->addr, *probed_mod) &&
1607 !module_is_coming(*probed_mod)) {
1608 module_put(*probed_mod);
1609 *probed_mod = NULL;
1610 ret = -ENOENT;
1611 }
1612 }
1613
1614out:
1615 preempt_enable();
1616 jump_label_unlock();
1617
1618 return ret;
1619}
1620
1621int register_kprobe(struct kprobe *p)
1622{
1623 int ret;
1624 struct kprobe *old_p;
1625 struct module *probed_mod;
1626 kprobe_opcode_t *addr;
1627 bool on_func_entry;
1628
1629 /* Adjust probe address from symbol */
1630 addr = _kprobe_addr(p->addr, p->symbol_name, p->offset, &on_func_entry);
1631 if (IS_ERR(addr))
1632 return PTR_ERR(addr);
1633 p->addr = addr;
1634
1635 ret = warn_kprobe_rereg(p);
1636 if (ret)
1637 return ret;
1638
1639 /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
1640 p->flags &= KPROBE_FLAG_DISABLED;
1641 p->nmissed = 0;
1642 INIT_LIST_HEAD(&p->list);
1643
1644 ret = check_kprobe_address_safe(p, &probed_mod);
1645 if (ret)
1646 return ret;
1647
1648 mutex_lock(&kprobe_mutex);
1649
1650 if (on_func_entry)
1651 p->flags |= KPROBE_FLAG_ON_FUNC_ENTRY;
1652
1653 old_p = get_kprobe(p->addr);
1654 if (old_p) {
1655 /* Since this may unoptimize 'old_p', locking 'text_mutex'. */
1656 ret = register_aggr_kprobe(old_p, p);
1657 goto out;
1658 }
1659
1660 cpus_read_lock();
1661 /* Prevent text modification */
1662 mutex_lock(&text_mutex);
1663 ret = prepare_kprobe(p);
1664 mutex_unlock(&text_mutex);
1665 cpus_read_unlock();
1666 if (ret)
1667 goto out;
1668
1669 INIT_HLIST_NODE(&p->hlist);
1670 hlist_add_head_rcu(&p->hlist,
1671 &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
1672
1673 if (!kprobes_all_disarmed && !kprobe_disabled(p)) {
1674 ret = arm_kprobe(p);
1675 if (ret) {
1676 hlist_del_rcu(&p->hlist);
1677 synchronize_rcu();
1678 goto out;
1679 }
1680 }
1681
1682 /* Try to optimize kprobe */
1683 try_to_optimize_kprobe(p);
1684out:
1685 mutex_unlock(&kprobe_mutex);
1686
1687 if (probed_mod)
1688 module_put(probed_mod);
1689
1690 return ret;
1691}
1692EXPORT_SYMBOL_GPL(register_kprobe);
1693
1694/* Check if all probes on the 'ap' are disabled. */
1695static bool aggr_kprobe_disabled(struct kprobe *ap)
1696{
1697 struct kprobe *kp;
1698
1699 lockdep_assert_held(&kprobe_mutex);
1700
1701 list_for_each_entry(kp, &ap->list, list)
1702 if (!kprobe_disabled(kp))
1703 /*
1704 * Since there is an active probe on the list,
1705 * we can't disable this 'ap'.
1706 */
1707 return false;
1708
1709 return true;
1710}
1711
1712static struct kprobe *__disable_kprobe(struct kprobe *p)
1713{
1714 struct kprobe *orig_p;
1715 int ret;
1716
1717 lockdep_assert_held(&kprobe_mutex);
1718
1719 /* Get an original kprobe for return */
1720 orig_p = __get_valid_kprobe(p);
1721 if (unlikely(orig_p == NULL))
1722 return ERR_PTR(-EINVAL);
1723
1724 if (kprobe_disabled(p))
1725 return orig_p;
1726
1727 /* Disable probe if it is a child probe */
1728 if (p != orig_p)
1729 p->flags |= KPROBE_FLAG_DISABLED;
1730
1731 /* Try to disarm and disable this/parent probe */
1732 if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
1733 /*
1734 * Don't be lazy here. Even if 'kprobes_all_disarmed'
1735 * is false, 'orig_p' might not have been armed yet.
1736 * Note arm_all_kprobes() __tries__ to arm all kprobes
1737 * on the best effort basis.
1738 */
1739 if (!kprobes_all_disarmed && !kprobe_disabled(orig_p)) {
1740 ret = disarm_kprobe(orig_p, true);
1741 if (ret) {
1742 p->flags &= ~KPROBE_FLAG_DISABLED;
1743 return ERR_PTR(ret);
1744 }
1745 }
1746 orig_p->flags |= KPROBE_FLAG_DISABLED;
1747 }
1748
1749 return orig_p;
1750}
1751
1752/*
1753 * Unregister a kprobe without a scheduler synchronization.
1754 */
1755static int __unregister_kprobe_top(struct kprobe *p)
1756{
1757 struct kprobe *ap, *list_p;
1758
1759 /* Disable kprobe. This will disarm it if needed. */
1760 ap = __disable_kprobe(p);
1761 if (IS_ERR(ap))
1762 return PTR_ERR(ap);
1763
1764 if (ap == p)
1765 /*
1766 * This probe is an independent(and non-optimized) kprobe
1767 * (not an aggrprobe). Remove from the hash list.
1768 */
1769 goto disarmed;
1770
1771 /* Following process expects this probe is an aggrprobe */
1772 WARN_ON(!kprobe_aggrprobe(ap));
1773
1774 if (list_is_singular(&ap->list) && kprobe_disarmed(ap))
1775 /*
1776 * !disarmed could be happen if the probe is under delayed
1777 * unoptimizing.
1778 */
1779 goto disarmed;
1780 else {
1781 /* If disabling probe has special handlers, update aggrprobe */
1782 if (p->post_handler && !kprobe_gone(p)) {
1783 list_for_each_entry(list_p, &ap->list, list) {
1784 if ((list_p != p) && (list_p->post_handler))
1785 goto noclean;
1786 }
1787 /*
1788 * For the kprobe-on-ftrace case, we keep the
1789 * post_handler setting to identify this aggrprobe
1790 * armed with kprobe_ipmodify_ops.
1791 */
1792 if (!kprobe_ftrace(ap))
1793 ap->post_handler = NULL;
1794 }
1795noclean:
1796 /*
1797 * Remove from the aggrprobe: this path will do nothing in
1798 * __unregister_kprobe_bottom().
1799 */
1800 list_del_rcu(&p->list);
1801 if (!kprobe_disabled(ap) && !kprobes_all_disarmed)
1802 /*
1803 * Try to optimize this probe again, because post
1804 * handler may have been changed.
1805 */
1806 optimize_kprobe(ap);
1807 }
1808 return 0;
1809
1810disarmed:
1811 hlist_del_rcu(&ap->hlist);
1812 return 0;
1813}
1814
1815static void __unregister_kprobe_bottom(struct kprobe *p)
1816{
1817 struct kprobe *ap;
1818
1819 if (list_empty(&p->list))
1820 /* This is an independent kprobe */
1821 arch_remove_kprobe(p);
1822 else if (list_is_singular(&p->list)) {
1823 /* This is the last child of an aggrprobe */
1824 ap = list_entry(p->list.next, struct kprobe, list);
1825 list_del(&p->list);
1826 free_aggr_kprobe(ap);
1827 }
1828 /* Otherwise, do nothing. */
1829}
1830
1831int register_kprobes(struct kprobe **kps, int num)
1832{
1833 int i, ret = 0;
1834
1835 if (num <= 0)
1836 return -EINVAL;
1837 for (i = 0; i < num; i++) {
1838 ret = register_kprobe(kps[i]);
1839 if (ret < 0) {
1840 if (i > 0)
1841 unregister_kprobes(kps, i);
1842 break;
1843 }
1844 }
1845 return ret;
1846}
1847EXPORT_SYMBOL_GPL(register_kprobes);
1848
1849void unregister_kprobe(struct kprobe *p)
1850{
1851 unregister_kprobes(&p, 1);
1852}
1853EXPORT_SYMBOL_GPL(unregister_kprobe);
1854
1855void unregister_kprobes(struct kprobe **kps, int num)
1856{
1857 int i;
1858
1859 if (num <= 0)
1860 return;
1861 mutex_lock(&kprobe_mutex);
1862 for (i = 0; i < num; i++)
1863 if (__unregister_kprobe_top(kps[i]) < 0)
1864 kps[i]->addr = NULL;
1865 mutex_unlock(&kprobe_mutex);
1866
1867 synchronize_rcu();
1868 for (i = 0; i < num; i++)
1869 if (kps[i]->addr)
1870 __unregister_kprobe_bottom(kps[i]);
1871}
1872EXPORT_SYMBOL_GPL(unregister_kprobes);
1873
1874int __weak kprobe_exceptions_notify(struct notifier_block *self,
1875 unsigned long val, void *data)
1876{
1877 return NOTIFY_DONE;
1878}
1879NOKPROBE_SYMBOL(kprobe_exceptions_notify);
1880
1881static struct notifier_block kprobe_exceptions_nb = {
1882 .notifier_call = kprobe_exceptions_notify,
1883 .priority = 0x7fffffff /* we need to be notified first */
1884};
1885
1886#ifdef CONFIG_KRETPROBES
1887
1888#if !defined(CONFIG_KRETPROBE_ON_RETHOOK)
1889
1890/* callbacks for objpool of kretprobe instances */
1891static int kretprobe_init_inst(void *nod, void *context)
1892{
1893 struct kretprobe_instance *ri = nod;
1894
1895 ri->rph = context;
1896 return 0;
1897}
1898static int kretprobe_fini_pool(struct objpool_head *head, void *context)
1899{
1900 kfree(context);
1901 return 0;
1902}
1903
1904static void free_rp_inst_rcu(struct rcu_head *head)
1905{
1906 struct kretprobe_instance *ri = container_of(head, struct kretprobe_instance, rcu);
1907 struct kretprobe_holder *rph = ri->rph;
1908
1909 objpool_drop(ri, &rph->pool);
1910}
1911NOKPROBE_SYMBOL(free_rp_inst_rcu);
1912
1913static void recycle_rp_inst(struct kretprobe_instance *ri)
1914{
1915 struct kretprobe *rp = get_kretprobe(ri);
1916
1917 if (likely(rp))
1918 objpool_push(ri, &rp->rph->pool);
1919 else
1920 call_rcu(&ri->rcu, free_rp_inst_rcu);
1921}
1922NOKPROBE_SYMBOL(recycle_rp_inst);
1923
1924/*
1925 * This function is called from delayed_put_task_struct() when a task is
1926 * dead and cleaned up to recycle any kretprobe instances associated with
1927 * this task. These left over instances represent probed functions that
1928 * have been called but will never return.
1929 */
1930void kprobe_flush_task(struct task_struct *tk)
1931{
1932 struct kretprobe_instance *ri;
1933 struct llist_node *node;
1934
1935 /* Early boot, not yet initialized. */
1936 if (unlikely(!kprobes_initialized))
1937 return;
1938
1939 kprobe_busy_begin();
1940
1941 node = __llist_del_all(&tk->kretprobe_instances);
1942 while (node) {
1943 ri = container_of(node, struct kretprobe_instance, llist);
1944 node = node->next;
1945
1946 recycle_rp_inst(ri);
1947 }
1948
1949 kprobe_busy_end();
1950}
1951NOKPROBE_SYMBOL(kprobe_flush_task);
1952
1953static inline void free_rp_inst(struct kretprobe *rp)
1954{
1955 struct kretprobe_holder *rph = rp->rph;
1956
1957 if (!rph)
1958 return;
1959 rp->rph = NULL;
1960 objpool_fini(&rph->pool);
1961}
1962
1963/* This assumes the 'tsk' is the current task or the is not running. */
1964static kprobe_opcode_t *__kretprobe_find_ret_addr(struct task_struct *tsk,
1965 struct llist_node **cur)
1966{
1967 struct kretprobe_instance *ri = NULL;
1968 struct llist_node *node = *cur;
1969
1970 if (!node)
1971 node = tsk->kretprobe_instances.first;
1972 else
1973 node = node->next;
1974
1975 while (node) {
1976 ri = container_of(node, struct kretprobe_instance, llist);
1977 if (ri->ret_addr != kretprobe_trampoline_addr()) {
1978 *cur = node;
1979 return ri->ret_addr;
1980 }
1981 node = node->next;
1982 }
1983 return NULL;
1984}
1985NOKPROBE_SYMBOL(__kretprobe_find_ret_addr);
1986
1987/**
1988 * kretprobe_find_ret_addr -- Find correct return address modified by kretprobe
1989 * @tsk: Target task
1990 * @fp: A frame pointer
1991 * @cur: a storage of the loop cursor llist_node pointer for next call
1992 *
1993 * Find the correct return address modified by a kretprobe on @tsk in unsigned
1994 * long type. If it finds the return address, this returns that address value,
1995 * or this returns 0.
1996 * The @tsk must be 'current' or a task which is not running. @fp is a hint
1997 * to get the currect return address - which is compared with the
1998 * kretprobe_instance::fp field. The @cur is a loop cursor for searching the
1999 * kretprobe return addresses on the @tsk. The '*@cur' should be NULL at the
2000 * first call, but '@cur' itself must NOT NULL.
2001 */
2002unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
2003 struct llist_node **cur)
2004{
2005 struct kretprobe_instance *ri;
2006 kprobe_opcode_t *ret;
2007
2008 if (WARN_ON_ONCE(!cur))
2009 return 0;
2010
2011 do {
2012 ret = __kretprobe_find_ret_addr(tsk, cur);
2013 if (!ret)
2014 break;
2015 ri = container_of(*cur, struct kretprobe_instance, llist);
2016 } while (ri->fp != fp);
2017
2018 return (unsigned long)ret;
2019}
2020NOKPROBE_SYMBOL(kretprobe_find_ret_addr);
2021
2022void __weak arch_kretprobe_fixup_return(struct pt_regs *regs,
2023 kprobe_opcode_t *correct_ret_addr)
2024{
2025 /*
2026 * Do nothing by default. Please fill this to update the fake return
2027 * address on the stack with the correct one on each arch if possible.
2028 */
2029}
2030
2031unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
2032 void *frame_pointer)
2033{
2034 struct kretprobe_instance *ri = NULL;
2035 struct llist_node *first, *node = NULL;
2036 kprobe_opcode_t *correct_ret_addr;
2037 struct kretprobe *rp;
2038
2039 /* Find correct address and all nodes for this frame. */
2040 correct_ret_addr = __kretprobe_find_ret_addr(current, &node);
2041 if (!correct_ret_addr) {
2042 pr_err("kretprobe: Return address not found, not execute handler. Maybe there is a bug in the kernel.\n");
2043 BUG_ON(1);
2044 }
2045
2046 /*
2047 * Set the return address as the instruction pointer, because if the
2048 * user handler calls stack_trace_save_regs() with this 'regs',
2049 * the stack trace will start from the instruction pointer.
2050 */
2051 instruction_pointer_set(regs, (unsigned long)correct_ret_addr);
2052
2053 /* Run the user handler of the nodes. */
2054 first = current->kretprobe_instances.first;
2055 while (first) {
2056 ri = container_of(first, struct kretprobe_instance, llist);
2057
2058 if (WARN_ON_ONCE(ri->fp != frame_pointer))
2059 break;
2060
2061 rp = get_kretprobe(ri);
2062 if (rp && rp->handler) {
2063 struct kprobe *prev = kprobe_running();
2064
2065 __this_cpu_write(current_kprobe, &rp->kp);
2066 ri->ret_addr = correct_ret_addr;
2067 rp->handler(ri, regs);
2068 __this_cpu_write(current_kprobe, prev);
2069 }
2070 if (first == node)
2071 break;
2072
2073 first = first->next;
2074 }
2075
2076 arch_kretprobe_fixup_return(regs, correct_ret_addr);
2077
2078 /* Unlink all nodes for this frame. */
2079 first = current->kretprobe_instances.first;
2080 current->kretprobe_instances.first = node->next;
2081 node->next = NULL;
2082
2083 /* Recycle free instances. */
2084 while (first) {
2085 ri = container_of(first, struct kretprobe_instance, llist);
2086 first = first->next;
2087
2088 recycle_rp_inst(ri);
2089 }
2090
2091 return (unsigned long)correct_ret_addr;
2092}
2093NOKPROBE_SYMBOL(__kretprobe_trampoline_handler)
2094
2095/*
2096 * This kprobe pre_handler is registered with every kretprobe. When probe
2097 * hits it will set up the return probe.
2098 */
2099static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
2100{
2101 struct kretprobe *rp = container_of(p, struct kretprobe, kp);
2102 struct kretprobe_holder *rph = rp->rph;
2103 struct kretprobe_instance *ri;
2104
2105 ri = objpool_pop(&rph->pool);
2106 if (!ri) {
2107 rp->nmissed++;
2108 return 0;
2109 }
2110
2111 if (rp->entry_handler && rp->entry_handler(ri, regs)) {
2112 objpool_push(ri, &rph->pool);
2113 return 0;
2114 }
2115
2116 arch_prepare_kretprobe(ri, regs);
2117
2118 __llist_add(&ri->llist, ¤t->kretprobe_instances);
2119
2120 return 0;
2121}
2122NOKPROBE_SYMBOL(pre_handler_kretprobe);
2123#else /* CONFIG_KRETPROBE_ON_RETHOOK */
2124/*
2125 * This kprobe pre_handler is registered with every kretprobe. When probe
2126 * hits it will set up the return probe.
2127 */
2128static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
2129{
2130 struct kretprobe *rp = container_of(p, struct kretprobe, kp);
2131 struct kretprobe_instance *ri;
2132 struct rethook_node *rhn;
2133
2134 rhn = rethook_try_get(rp->rh);
2135 if (!rhn) {
2136 rp->nmissed++;
2137 return 0;
2138 }
2139
2140 ri = container_of(rhn, struct kretprobe_instance, node);
2141
2142 if (rp->entry_handler && rp->entry_handler(ri, regs))
2143 rethook_recycle(rhn);
2144 else
2145 rethook_hook(rhn, regs, kprobe_ftrace(p));
2146
2147 return 0;
2148}
2149NOKPROBE_SYMBOL(pre_handler_kretprobe);
2150
2151static void kretprobe_rethook_handler(struct rethook_node *rh, void *data,
2152 unsigned long ret_addr,
2153 struct pt_regs *regs)
2154{
2155 struct kretprobe *rp = (struct kretprobe *)data;
2156 struct kretprobe_instance *ri;
2157 struct kprobe_ctlblk *kcb;
2158
2159 /* The data must NOT be null. This means rethook data structure is broken. */
2160 if (WARN_ON_ONCE(!data) || !rp->handler)
2161 return;
2162
2163 __this_cpu_write(current_kprobe, &rp->kp);
2164 kcb = get_kprobe_ctlblk();
2165 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
2166
2167 ri = container_of(rh, struct kretprobe_instance, node);
2168 rp->handler(ri, regs);
2169
2170 __this_cpu_write(current_kprobe, NULL);
2171}
2172NOKPROBE_SYMBOL(kretprobe_rethook_handler);
2173
2174#endif /* !CONFIG_KRETPROBE_ON_RETHOOK */
2175
2176/**
2177 * kprobe_on_func_entry() -- check whether given address is function entry
2178 * @addr: Target address
2179 * @sym: Target symbol name
2180 * @offset: The offset from the symbol or the address
2181 *
2182 * This checks whether the given @addr+@offset or @sym+@offset is on the
2183 * function entry address or not.
2184 * This returns 0 if it is the function entry, or -EINVAL if it is not.
2185 * And also it returns -ENOENT if it fails the symbol or address lookup.
2186 * Caller must pass @addr or @sym (either one must be NULL), or this
2187 * returns -EINVAL.
2188 */
2189int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset)
2190{
2191 bool on_func_entry;
2192 kprobe_opcode_t *kp_addr = _kprobe_addr(addr, sym, offset, &on_func_entry);
2193
2194 if (IS_ERR(kp_addr))
2195 return PTR_ERR(kp_addr);
2196
2197 if (!on_func_entry)
2198 return -EINVAL;
2199
2200 return 0;
2201}
2202
2203int register_kretprobe(struct kretprobe *rp)
2204{
2205 int ret;
2206 int i;
2207 void *addr;
2208
2209 ret = kprobe_on_func_entry(rp->kp.addr, rp->kp.symbol_name, rp->kp.offset);
2210 if (ret)
2211 return ret;
2212
2213 /* If only 'rp->kp.addr' is specified, check reregistering kprobes */
2214 if (rp->kp.addr && warn_kprobe_rereg(&rp->kp))
2215 return -EINVAL;
2216
2217 if (kretprobe_blacklist_size) {
2218 addr = kprobe_addr(&rp->kp);
2219 if (IS_ERR(addr))
2220 return PTR_ERR(addr);
2221
2222 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
2223 if (kretprobe_blacklist[i].addr == addr)
2224 return -EINVAL;
2225 }
2226 }
2227
2228 if (rp->data_size > KRETPROBE_MAX_DATA_SIZE)
2229 return -E2BIG;
2230
2231 rp->kp.pre_handler = pre_handler_kretprobe;
2232 rp->kp.post_handler = NULL;
2233
2234 /* Pre-allocate memory for max kretprobe instances */
2235 if (rp->maxactive <= 0)
2236 rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
2237
2238#ifdef CONFIG_KRETPROBE_ON_RETHOOK
2239 rp->rh = rethook_alloc((void *)rp, kretprobe_rethook_handler,
2240 sizeof(struct kretprobe_instance) +
2241 rp->data_size, rp->maxactive);
2242 if (IS_ERR(rp->rh))
2243 return PTR_ERR(rp->rh);
2244
2245 rp->nmissed = 0;
2246 /* Establish function entry probe point */
2247 ret = register_kprobe(&rp->kp);
2248 if (ret != 0) {
2249 rethook_free(rp->rh);
2250 rp->rh = NULL;
2251 }
2252#else /* !CONFIG_KRETPROBE_ON_RETHOOK */
2253 rp->rph = kzalloc(sizeof(struct kretprobe_holder), GFP_KERNEL);
2254 if (!rp->rph)
2255 return -ENOMEM;
2256
2257 if (objpool_init(&rp->rph->pool, rp->maxactive, rp->data_size +
2258 sizeof(struct kretprobe_instance), GFP_KERNEL,
2259 rp->rph, kretprobe_init_inst, kretprobe_fini_pool)) {
2260 kfree(rp->rph);
2261 rp->rph = NULL;
2262 return -ENOMEM;
2263 }
2264 rcu_assign_pointer(rp->rph->rp, rp);
2265 rp->nmissed = 0;
2266 /* Establish function entry probe point */
2267 ret = register_kprobe(&rp->kp);
2268 if (ret != 0)
2269 free_rp_inst(rp);
2270#endif
2271 return ret;
2272}
2273EXPORT_SYMBOL_GPL(register_kretprobe);
2274
2275int register_kretprobes(struct kretprobe **rps, int num)
2276{
2277 int ret = 0, i;
2278
2279 if (num <= 0)
2280 return -EINVAL;
2281 for (i = 0; i < num; i++) {
2282 ret = register_kretprobe(rps[i]);
2283 if (ret < 0) {
2284 if (i > 0)
2285 unregister_kretprobes(rps, i);
2286 break;
2287 }
2288 }
2289 return ret;
2290}
2291EXPORT_SYMBOL_GPL(register_kretprobes);
2292
2293void unregister_kretprobe(struct kretprobe *rp)
2294{
2295 unregister_kretprobes(&rp, 1);
2296}
2297EXPORT_SYMBOL_GPL(unregister_kretprobe);
2298
2299void unregister_kretprobes(struct kretprobe **rps, int num)
2300{
2301 int i;
2302
2303 if (num <= 0)
2304 return;
2305 mutex_lock(&kprobe_mutex);
2306 for (i = 0; i < num; i++) {
2307 if (__unregister_kprobe_top(&rps[i]->kp) < 0)
2308 rps[i]->kp.addr = NULL;
2309#ifdef CONFIG_KRETPROBE_ON_RETHOOK
2310 rethook_free(rps[i]->rh);
2311#else
2312 rcu_assign_pointer(rps[i]->rph->rp, NULL);
2313#endif
2314 }
2315 mutex_unlock(&kprobe_mutex);
2316
2317 synchronize_rcu();
2318 for (i = 0; i < num; i++) {
2319 if (rps[i]->kp.addr) {
2320 __unregister_kprobe_bottom(&rps[i]->kp);
2321#ifndef CONFIG_KRETPROBE_ON_RETHOOK
2322 free_rp_inst(rps[i]);
2323#endif
2324 }
2325 }
2326}
2327EXPORT_SYMBOL_GPL(unregister_kretprobes);
2328
2329#else /* CONFIG_KRETPROBES */
2330int register_kretprobe(struct kretprobe *rp)
2331{
2332 return -EOPNOTSUPP;
2333}
2334EXPORT_SYMBOL_GPL(register_kretprobe);
2335
2336int register_kretprobes(struct kretprobe **rps, int num)
2337{
2338 return -EOPNOTSUPP;
2339}
2340EXPORT_SYMBOL_GPL(register_kretprobes);
2341
2342void unregister_kretprobe(struct kretprobe *rp)
2343{
2344}
2345EXPORT_SYMBOL_GPL(unregister_kretprobe);
2346
2347void unregister_kretprobes(struct kretprobe **rps, int num)
2348{
2349}
2350EXPORT_SYMBOL_GPL(unregister_kretprobes);
2351
2352static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
2353{
2354 return 0;
2355}
2356NOKPROBE_SYMBOL(pre_handler_kretprobe);
2357
2358#endif /* CONFIG_KRETPROBES */
2359
2360/* Set the kprobe gone and remove its instruction buffer. */
2361static void kill_kprobe(struct kprobe *p)
2362{
2363 struct kprobe *kp;
2364
2365 lockdep_assert_held(&kprobe_mutex);
2366
2367 /*
2368 * The module is going away. We should disarm the kprobe which
2369 * is using ftrace, because ftrace framework is still available at
2370 * 'MODULE_STATE_GOING' notification.
2371 */
2372 if (kprobe_ftrace(p) && !kprobe_disabled(p) && !kprobes_all_disarmed)
2373 disarm_kprobe_ftrace(p);
2374
2375 p->flags |= KPROBE_FLAG_GONE;
2376 if (kprobe_aggrprobe(p)) {
2377 /*
2378 * If this is an aggr_kprobe, we have to list all the
2379 * chained probes and mark them GONE.
2380 */
2381 list_for_each_entry(kp, &p->list, list)
2382 kp->flags |= KPROBE_FLAG_GONE;
2383 p->post_handler = NULL;
2384 kill_optimized_kprobe(p);
2385 }
2386 /*
2387 * Here, we can remove insn_slot safely, because no thread calls
2388 * the original probed function (which will be freed soon) any more.
2389 */
2390 arch_remove_kprobe(p);
2391}
2392
2393/* Disable one kprobe */
2394int disable_kprobe(struct kprobe *kp)
2395{
2396 int ret = 0;
2397 struct kprobe *p;
2398
2399 mutex_lock(&kprobe_mutex);
2400
2401 /* Disable this kprobe */
2402 p = __disable_kprobe(kp);
2403 if (IS_ERR(p))
2404 ret = PTR_ERR(p);
2405
2406 mutex_unlock(&kprobe_mutex);
2407 return ret;
2408}
2409EXPORT_SYMBOL_GPL(disable_kprobe);
2410
2411/* Enable one kprobe */
2412int enable_kprobe(struct kprobe *kp)
2413{
2414 int ret = 0;
2415 struct kprobe *p;
2416
2417 mutex_lock(&kprobe_mutex);
2418
2419 /* Check whether specified probe is valid. */
2420 p = __get_valid_kprobe(kp);
2421 if (unlikely(p == NULL)) {
2422 ret = -EINVAL;
2423 goto out;
2424 }
2425
2426 if (kprobe_gone(kp)) {
2427 /* This kprobe has gone, we couldn't enable it. */
2428 ret = -EINVAL;
2429 goto out;
2430 }
2431
2432 if (p != kp)
2433 kp->flags &= ~KPROBE_FLAG_DISABLED;
2434
2435 if (!kprobes_all_disarmed && kprobe_disabled(p)) {
2436 p->flags &= ~KPROBE_FLAG_DISABLED;
2437 ret = arm_kprobe(p);
2438 if (ret) {
2439 p->flags |= KPROBE_FLAG_DISABLED;
2440 if (p != kp)
2441 kp->flags |= KPROBE_FLAG_DISABLED;
2442 }
2443 }
2444out:
2445 mutex_unlock(&kprobe_mutex);
2446 return ret;
2447}
2448EXPORT_SYMBOL_GPL(enable_kprobe);
2449
2450/* Caller must NOT call this in usual path. This is only for critical case */
2451void dump_kprobe(struct kprobe *kp)
2452{
2453 pr_err("Dump kprobe:\n.symbol_name = %s, .offset = %x, .addr = %pS\n",
2454 kp->symbol_name, kp->offset, kp->addr);
2455}
2456NOKPROBE_SYMBOL(dump_kprobe);
2457
2458int kprobe_add_ksym_blacklist(unsigned long entry)
2459{
2460 struct kprobe_blacklist_entry *ent;
2461 unsigned long offset = 0, size = 0;
2462
2463 if (!kernel_text_address(entry) ||
2464 !kallsyms_lookup_size_offset(entry, &size, &offset))
2465 return -EINVAL;
2466
2467 ent = kmalloc(sizeof(*ent), GFP_KERNEL);
2468 if (!ent)
2469 return -ENOMEM;
2470 ent->start_addr = entry;
2471 ent->end_addr = entry + size;
2472 INIT_LIST_HEAD(&ent->list);
2473 list_add_tail(&ent->list, &kprobe_blacklist);
2474
2475 return (int)size;
2476}
2477
2478/* Add all symbols in given area into kprobe blacklist */
2479int kprobe_add_area_blacklist(unsigned long start, unsigned long end)
2480{
2481 unsigned long entry;
2482 int ret = 0;
2483
2484 for (entry = start; entry < end; entry += ret) {
2485 ret = kprobe_add_ksym_blacklist(entry);
2486 if (ret < 0)
2487 return ret;
2488 if (ret == 0) /* In case of alias symbol */
2489 ret = 1;
2490 }
2491 return 0;
2492}
2493
2494int __weak arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value,
2495 char *type, char *sym)
2496{
2497 return -ERANGE;
2498}
2499
2500int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
2501 char *sym)
2502{
2503#ifdef __ARCH_WANT_KPROBES_INSN_SLOT
2504 if (!kprobe_cache_get_kallsym(&kprobe_insn_slots, &symnum, value, type, sym))
2505 return 0;
2506#ifdef CONFIG_OPTPROBES
2507 if (!kprobe_cache_get_kallsym(&kprobe_optinsn_slots, &symnum, value, type, sym))
2508 return 0;
2509#endif
2510#endif
2511 if (!arch_kprobe_get_kallsym(&symnum, value, type, sym))
2512 return 0;
2513 return -ERANGE;
2514}
2515
2516int __init __weak arch_populate_kprobe_blacklist(void)
2517{
2518 return 0;
2519}
2520
2521/*
2522 * Lookup and populate the kprobe_blacklist.
2523 *
2524 * Unlike the kretprobe blacklist, we'll need to determine
2525 * the range of addresses that belong to the said functions,
2526 * since a kprobe need not necessarily be at the beginning
2527 * of a function.
2528 */
2529static int __init populate_kprobe_blacklist(unsigned long *start,
2530 unsigned long *end)
2531{
2532 unsigned long entry;
2533 unsigned long *iter;
2534 int ret;
2535
2536 for (iter = start; iter < end; iter++) {
2537 entry = (unsigned long)dereference_symbol_descriptor((void *)*iter);
2538 ret = kprobe_add_ksym_blacklist(entry);
2539 if (ret == -EINVAL)
2540 continue;
2541 if (ret < 0)
2542 return ret;
2543 }
2544
2545 /* Symbols in '__kprobes_text' are blacklisted */
2546 ret = kprobe_add_area_blacklist((unsigned long)__kprobes_text_start,
2547 (unsigned long)__kprobes_text_end);
2548 if (ret)
2549 return ret;
2550
2551 /* Symbols in 'noinstr' section are blacklisted */
2552 ret = kprobe_add_area_blacklist((unsigned long)__noinstr_text_start,
2553 (unsigned long)__noinstr_text_end);
2554
2555 return ret ? : arch_populate_kprobe_blacklist();
2556}
2557
2558#ifdef CONFIG_MODULES
2559/* Remove all symbols in given area from kprobe blacklist */
2560static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end)
2561{
2562 struct kprobe_blacklist_entry *ent, *n;
2563
2564 list_for_each_entry_safe(ent, n, &kprobe_blacklist, list) {
2565 if (ent->start_addr < start || ent->start_addr >= end)
2566 continue;
2567 list_del(&ent->list);
2568 kfree(ent);
2569 }
2570}
2571
2572static void kprobe_remove_ksym_blacklist(unsigned long entry)
2573{
2574 kprobe_remove_area_blacklist(entry, entry + 1);
2575}
2576
2577static void add_module_kprobe_blacklist(struct module *mod)
2578{
2579 unsigned long start, end;
2580 int i;
2581
2582 if (mod->kprobe_blacklist) {
2583 for (i = 0; i < mod->num_kprobe_blacklist; i++)
2584 kprobe_add_ksym_blacklist(mod->kprobe_blacklist[i]);
2585 }
2586
2587 start = (unsigned long)mod->kprobes_text_start;
2588 if (start) {
2589 end = start + mod->kprobes_text_size;
2590 kprobe_add_area_blacklist(start, end);
2591 }
2592
2593 start = (unsigned long)mod->noinstr_text_start;
2594 if (start) {
2595 end = start + mod->noinstr_text_size;
2596 kprobe_add_area_blacklist(start, end);
2597 }
2598}
2599
2600static void remove_module_kprobe_blacklist(struct module *mod)
2601{
2602 unsigned long start, end;
2603 int i;
2604
2605 if (mod->kprobe_blacklist) {
2606 for (i = 0; i < mod->num_kprobe_blacklist; i++)
2607 kprobe_remove_ksym_blacklist(mod->kprobe_blacklist[i]);
2608 }
2609
2610 start = (unsigned long)mod->kprobes_text_start;
2611 if (start) {
2612 end = start + mod->kprobes_text_size;
2613 kprobe_remove_area_blacklist(start, end);
2614 }
2615
2616 start = (unsigned long)mod->noinstr_text_start;
2617 if (start) {
2618 end = start + mod->noinstr_text_size;
2619 kprobe_remove_area_blacklist(start, end);
2620 }
2621}
2622
2623/* Module notifier call back, checking kprobes on the module */
2624static int kprobes_module_callback(struct notifier_block *nb,
2625 unsigned long val, void *data)
2626{
2627 struct module *mod = data;
2628 struct hlist_head *head;
2629 struct kprobe *p;
2630 unsigned int i;
2631 int checkcore = (val == MODULE_STATE_GOING);
2632
2633 if (val == MODULE_STATE_COMING) {
2634 mutex_lock(&kprobe_mutex);
2635 add_module_kprobe_blacklist(mod);
2636 mutex_unlock(&kprobe_mutex);
2637 }
2638 if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
2639 return NOTIFY_DONE;
2640
2641 /*
2642 * When 'MODULE_STATE_GOING' was notified, both of module '.text' and
2643 * '.init.text' sections would be freed. When 'MODULE_STATE_LIVE' was
2644 * notified, only '.init.text' section would be freed. We need to
2645 * disable kprobes which have been inserted in the sections.
2646 */
2647 mutex_lock(&kprobe_mutex);
2648 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2649 head = &kprobe_table[i];
2650 hlist_for_each_entry(p, head, hlist)
2651 if (within_module_init((unsigned long)p->addr, mod) ||
2652 (checkcore &&
2653 within_module_core((unsigned long)p->addr, mod))) {
2654 /*
2655 * The vaddr this probe is installed will soon
2656 * be vfreed buy not synced to disk. Hence,
2657 * disarming the breakpoint isn't needed.
2658 *
2659 * Note, this will also move any optimized probes
2660 * that are pending to be removed from their
2661 * corresponding lists to the 'freeing_list' and
2662 * will not be touched by the delayed
2663 * kprobe_optimizer() work handler.
2664 */
2665 kill_kprobe(p);
2666 }
2667 }
2668 if (val == MODULE_STATE_GOING)
2669 remove_module_kprobe_blacklist(mod);
2670 mutex_unlock(&kprobe_mutex);
2671 return NOTIFY_DONE;
2672}
2673
2674static struct notifier_block kprobe_module_nb = {
2675 .notifier_call = kprobes_module_callback,
2676 .priority = 0
2677};
2678
2679static int kprobe_register_module_notifier(void)
2680{
2681 return register_module_notifier(&kprobe_module_nb);
2682}
2683#else
2684static int kprobe_register_module_notifier(void)
2685{
2686 return 0;
2687}
2688#endif /* CONFIG_MODULES */
2689
2690void kprobe_free_init_mem(void)
2691{
2692 void *start = (void *)(&__init_begin);
2693 void *end = (void *)(&__init_end);
2694 struct hlist_head *head;
2695 struct kprobe *p;
2696 int i;
2697
2698 mutex_lock(&kprobe_mutex);
2699
2700 /* Kill all kprobes on initmem because the target code has been freed. */
2701 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2702 head = &kprobe_table[i];
2703 hlist_for_each_entry(p, head, hlist) {
2704 if (start <= (void *)p->addr && (void *)p->addr < end)
2705 kill_kprobe(p);
2706 }
2707 }
2708
2709 mutex_unlock(&kprobe_mutex);
2710}
2711
2712static int __init init_kprobes(void)
2713{
2714 int i, err;
2715
2716 /* FIXME allocate the probe table, currently defined statically */
2717 /* initialize all list heads */
2718 for (i = 0; i < KPROBE_TABLE_SIZE; i++)
2719 INIT_HLIST_HEAD(&kprobe_table[i]);
2720
2721 err = populate_kprobe_blacklist(__start_kprobe_blacklist,
2722 __stop_kprobe_blacklist);
2723 if (err)
2724 pr_err("Failed to populate blacklist (error %d), kprobes not restricted, be careful using them!\n", err);
2725
2726 if (kretprobe_blacklist_size) {
2727 /* lookup the function address from its name */
2728 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
2729 kretprobe_blacklist[i].addr =
2730 kprobe_lookup_name(kretprobe_blacklist[i].name, 0);
2731 if (!kretprobe_blacklist[i].addr)
2732 pr_err("Failed to lookup symbol '%s' for kretprobe blacklist. Maybe the target function is removed or renamed.\n",
2733 kretprobe_blacklist[i].name);
2734 }
2735 }
2736
2737 /* By default, kprobes are armed */
2738 kprobes_all_disarmed = false;
2739
2740#if defined(CONFIG_OPTPROBES) && defined(__ARCH_WANT_KPROBES_INSN_SLOT)
2741 /* Init 'kprobe_optinsn_slots' for allocation */
2742 kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
2743#endif
2744
2745 err = arch_init_kprobes();
2746 if (!err)
2747 err = register_die_notifier(&kprobe_exceptions_nb);
2748 if (!err)
2749 err = kprobe_register_module_notifier();
2750
2751 kprobes_initialized = (err == 0);
2752 kprobe_sysctls_init();
2753 return err;
2754}
2755early_initcall(init_kprobes);
2756
2757#if defined(CONFIG_OPTPROBES)
2758static int __init init_optprobes(void)
2759{
2760 /*
2761 * Enable kprobe optimization - this kicks the optimizer which
2762 * depends on synchronize_rcu_tasks() and ksoftirqd, that is
2763 * not spawned in early initcall. So delay the optimization.
2764 */
2765 optimize_all_kprobes();
2766
2767 return 0;
2768}
2769subsys_initcall(init_optprobes);
2770#endif
2771
2772#ifdef CONFIG_DEBUG_FS
2773static void report_probe(struct seq_file *pi, struct kprobe *p,
2774 const char *sym, int offset, char *modname, struct kprobe *pp)
2775{
2776 char *kprobe_type;
2777 void *addr = p->addr;
2778
2779 if (p->pre_handler == pre_handler_kretprobe)
2780 kprobe_type = "r";
2781 else
2782 kprobe_type = "k";
2783
2784 if (!kallsyms_show_value(pi->file->f_cred))
2785 addr = NULL;
2786
2787 if (sym)
2788 seq_printf(pi, "%px %s %s+0x%x %s ",
2789 addr, kprobe_type, sym, offset,
2790 (modname ? modname : " "));
2791 else /* try to use %pS */
2792 seq_printf(pi, "%px %s %pS ",
2793 addr, kprobe_type, p->addr);
2794
2795 if (!pp)
2796 pp = p;
2797 seq_printf(pi, "%s%s%s%s\n",
2798 (kprobe_gone(p) ? "[GONE]" : ""),
2799 ((kprobe_disabled(p) && !kprobe_gone(p)) ? "[DISABLED]" : ""),
2800 (kprobe_optimized(pp) ? "[OPTIMIZED]" : ""),
2801 (kprobe_ftrace(pp) ? "[FTRACE]" : ""));
2802}
2803
2804static void *kprobe_seq_start(struct seq_file *f, loff_t *pos)
2805{
2806 return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
2807}
2808
2809static void *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
2810{
2811 (*pos)++;
2812 if (*pos >= KPROBE_TABLE_SIZE)
2813 return NULL;
2814 return pos;
2815}
2816
2817static void kprobe_seq_stop(struct seq_file *f, void *v)
2818{
2819 /* Nothing to do */
2820}
2821
2822static int show_kprobe_addr(struct seq_file *pi, void *v)
2823{
2824 struct hlist_head *head;
2825 struct kprobe *p, *kp;
2826 const char *sym;
2827 unsigned int i = *(loff_t *) v;
2828 unsigned long offset = 0;
2829 char *modname, namebuf[KSYM_NAME_LEN];
2830
2831 head = &kprobe_table[i];
2832 preempt_disable();
2833 hlist_for_each_entry_rcu(p, head, hlist) {
2834 sym = kallsyms_lookup((unsigned long)p->addr, NULL,
2835 &offset, &modname, namebuf);
2836 if (kprobe_aggrprobe(p)) {
2837 list_for_each_entry_rcu(kp, &p->list, list)
2838 report_probe(pi, kp, sym, offset, modname, p);
2839 } else
2840 report_probe(pi, p, sym, offset, modname, NULL);
2841 }
2842 preempt_enable();
2843 return 0;
2844}
2845
2846static const struct seq_operations kprobes_sops = {
2847 .start = kprobe_seq_start,
2848 .next = kprobe_seq_next,
2849 .stop = kprobe_seq_stop,
2850 .show = show_kprobe_addr
2851};
2852
2853DEFINE_SEQ_ATTRIBUTE(kprobes);
2854
2855/* kprobes/blacklist -- shows which functions can not be probed */
2856static void *kprobe_blacklist_seq_start(struct seq_file *m, loff_t *pos)
2857{
2858 mutex_lock(&kprobe_mutex);
2859 return seq_list_start(&kprobe_blacklist, *pos);
2860}
2861
2862static void *kprobe_blacklist_seq_next(struct seq_file *m, void *v, loff_t *pos)
2863{
2864 return seq_list_next(v, &kprobe_blacklist, pos);
2865}
2866
2867static int kprobe_blacklist_seq_show(struct seq_file *m, void *v)
2868{
2869 struct kprobe_blacklist_entry *ent =
2870 list_entry(v, struct kprobe_blacklist_entry, list);
2871
2872 /*
2873 * If '/proc/kallsyms' is not showing kernel address, we won't
2874 * show them here either.
2875 */
2876 if (!kallsyms_show_value(m->file->f_cred))
2877 seq_printf(m, "0x%px-0x%px\t%ps\n", NULL, NULL,
2878 (void *)ent->start_addr);
2879 else
2880 seq_printf(m, "0x%px-0x%px\t%ps\n", (void *)ent->start_addr,
2881 (void *)ent->end_addr, (void *)ent->start_addr);
2882 return 0;
2883}
2884
2885static void kprobe_blacklist_seq_stop(struct seq_file *f, void *v)
2886{
2887 mutex_unlock(&kprobe_mutex);
2888}
2889
2890static const struct seq_operations kprobe_blacklist_sops = {
2891 .start = kprobe_blacklist_seq_start,
2892 .next = kprobe_blacklist_seq_next,
2893 .stop = kprobe_blacklist_seq_stop,
2894 .show = kprobe_blacklist_seq_show,
2895};
2896DEFINE_SEQ_ATTRIBUTE(kprobe_blacklist);
2897
2898static int arm_all_kprobes(void)
2899{
2900 struct hlist_head *head;
2901 struct kprobe *p;
2902 unsigned int i, total = 0, errors = 0;
2903 int err, ret = 0;
2904
2905 mutex_lock(&kprobe_mutex);
2906
2907 /* If kprobes are armed, just return */
2908 if (!kprobes_all_disarmed)
2909 goto already_enabled;
2910
2911 /*
2912 * optimize_kprobe() called by arm_kprobe() checks
2913 * kprobes_all_disarmed, so set kprobes_all_disarmed before
2914 * arm_kprobe.
2915 */
2916 kprobes_all_disarmed = false;
2917 /* Arming kprobes doesn't optimize kprobe itself */
2918 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2919 head = &kprobe_table[i];
2920 /* Arm all kprobes on a best-effort basis */
2921 hlist_for_each_entry(p, head, hlist) {
2922 if (!kprobe_disabled(p)) {
2923 err = arm_kprobe(p);
2924 if (err) {
2925 errors++;
2926 ret = err;
2927 }
2928 total++;
2929 }
2930 }
2931 }
2932
2933 if (errors)
2934 pr_warn("Kprobes globally enabled, but failed to enable %d out of %d probes. Please check which kprobes are kept disabled via debugfs.\n",
2935 errors, total);
2936 else
2937 pr_info("Kprobes globally enabled\n");
2938
2939already_enabled:
2940 mutex_unlock(&kprobe_mutex);
2941 return ret;
2942}
2943
2944static int disarm_all_kprobes(void)
2945{
2946 struct hlist_head *head;
2947 struct kprobe *p;
2948 unsigned int i, total = 0, errors = 0;
2949 int err, ret = 0;
2950
2951 mutex_lock(&kprobe_mutex);
2952
2953 /* If kprobes are already disarmed, just return */
2954 if (kprobes_all_disarmed) {
2955 mutex_unlock(&kprobe_mutex);
2956 return 0;
2957 }
2958
2959 kprobes_all_disarmed = true;
2960
2961 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2962 head = &kprobe_table[i];
2963 /* Disarm all kprobes on a best-effort basis */
2964 hlist_for_each_entry(p, head, hlist) {
2965 if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p)) {
2966 err = disarm_kprobe(p, false);
2967 if (err) {
2968 errors++;
2969 ret = err;
2970 }
2971 total++;
2972 }
2973 }
2974 }
2975
2976 if (errors)
2977 pr_warn("Kprobes globally disabled, but failed to disable %d out of %d probes. Please check which kprobes are kept enabled via debugfs.\n",
2978 errors, total);
2979 else
2980 pr_info("Kprobes globally disabled\n");
2981
2982 mutex_unlock(&kprobe_mutex);
2983
2984 /* Wait for disarming all kprobes by optimizer */
2985 wait_for_kprobe_optimizer();
2986
2987 return ret;
2988}
2989
2990/*
2991 * XXX: The debugfs bool file interface doesn't allow for callbacks
2992 * when the bool state is switched. We can reuse that facility when
2993 * available
2994 */
2995static ssize_t read_enabled_file_bool(struct file *file,
2996 char __user *user_buf, size_t count, loff_t *ppos)
2997{
2998 char buf[3];
2999
3000 if (!kprobes_all_disarmed)
3001 buf[0] = '1';
3002 else
3003 buf[0] = '0';
3004 buf[1] = '\n';
3005 buf[2] = 0x00;
3006 return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
3007}
3008
3009static ssize_t write_enabled_file_bool(struct file *file,
3010 const char __user *user_buf, size_t count, loff_t *ppos)
3011{
3012 bool enable;
3013 int ret;
3014
3015 ret = kstrtobool_from_user(user_buf, count, &enable);
3016 if (ret)
3017 return ret;
3018
3019 ret = enable ? arm_all_kprobes() : disarm_all_kprobes();
3020 if (ret)
3021 return ret;
3022
3023 return count;
3024}
3025
3026static const struct file_operations fops_kp = {
3027 .read = read_enabled_file_bool,
3028 .write = write_enabled_file_bool,
3029 .llseek = default_llseek,
3030};
3031
3032static int __init debugfs_kprobe_init(void)
3033{
3034 struct dentry *dir;
3035
3036 dir = debugfs_create_dir("kprobes", NULL);
3037
3038 debugfs_create_file("list", 0400, dir, NULL, &kprobes_fops);
3039
3040 debugfs_create_file("enabled", 0600, dir, NULL, &fops_kp);
3041
3042 debugfs_create_file("blacklist", 0400, dir, NULL,
3043 &kprobe_blacklist_fops);
3044
3045 return 0;
3046}
3047
3048late_initcall(debugfs_kprobe_init);
3049#endif /* CONFIG_DEBUG_FS */
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 */