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1 | /* | |
2 | * Kernel Probes (KProbes) | |
3 | * kernel/kprobes.c | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License as published by | |
7 | * the Free Software Foundation; either version 2 of the License, or | |
8 | * (at your option) any later version. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, | |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | * GNU General Public License for more details. | |
14 | * | |
15 | * You should have received a copy of the GNU General Public License | |
16 | * along with this program; if not, write to the Free Software | |
17 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
18 | * | |
19 | * Copyright (C) IBM Corporation, 2002, 2004 | |
20 | * | |
21 | * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel | |
22 | * Probes initial implementation (includes suggestions from | |
23 | * Rusty Russell). | |
24 | * 2004-Aug Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with | |
25 | * hlists and exceptions notifier as suggested by Andi Kleen. | |
26 | * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes | |
27 | * interface to access function arguments. | |
28 | * 2004-Sep Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes | |
29 | * exceptions notifier to be first on the priority list. | |
30 | * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston | |
31 | * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi | |
32 | * <prasanna@in.ibm.com> added function-return probes. | |
33 | */ | |
34 | #include <linux/kprobes.h> | |
35 | #include <linux/hash.h> | |
36 | #include <linux/init.h> | |
37 | #include <linux/slab.h> | |
38 | #include <linux/stddef.h> | |
39 | #include <linux/export.h> | |
40 | #include <linux/moduleloader.h> | |
41 | #include <linux/kallsyms.h> | |
42 | #include <linux/freezer.h> | |
43 | #include <linux/seq_file.h> | |
44 | #include <linux/debugfs.h> | |
45 | #include <linux/sysctl.h> | |
46 | #include <linux/kdebug.h> | |
47 | #include <linux/memory.h> | |
48 | #include <linux/ftrace.h> | |
49 | #include <linux/cpu.h> | |
50 | #include <linux/jump_label.h> | |
51 | ||
52 | #include <asm/sections.h> | |
53 | #include <asm/cacheflush.h> | |
54 | #include <asm/errno.h> | |
55 | #include <linux/uaccess.h> | |
56 | ||
57 | #define KPROBE_HASH_BITS 6 | |
58 | #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS) | |
59 | ||
60 | ||
61 | static int kprobes_initialized; | |
62 | static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; | |
63 | static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE]; | |
64 | ||
65 | /* NOTE: change this value only with kprobe_mutex held */ | |
66 | static bool kprobes_all_disarmed; | |
67 | ||
68 | /* This protects kprobe_table and optimizing_list */ | |
69 | static DEFINE_MUTEX(kprobe_mutex); | |
70 | static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL; | |
71 | static struct { | |
72 | raw_spinlock_t lock ____cacheline_aligned_in_smp; | |
73 | } kretprobe_table_locks[KPROBE_TABLE_SIZE]; | |
74 | ||
75 | kprobe_opcode_t * __weak kprobe_lookup_name(const char *name, | |
76 | unsigned int __unused) | |
77 | { | |
78 | return ((kprobe_opcode_t *)(kallsyms_lookup_name(name))); | |
79 | } | |
80 | ||
81 | static raw_spinlock_t *kretprobe_table_lock_ptr(unsigned long hash) | |
82 | { | |
83 | return &(kretprobe_table_locks[hash].lock); | |
84 | } | |
85 | ||
86 | /* Blacklist -- list of struct kprobe_blacklist_entry */ | |
87 | static LIST_HEAD(kprobe_blacklist); | |
88 | ||
89 | #ifdef __ARCH_WANT_KPROBES_INSN_SLOT | |
90 | /* | |
91 | * kprobe->ainsn.insn points to the copy of the instruction to be | |
92 | * single-stepped. x86_64, POWER4 and above have no-exec support and | |
93 | * stepping on the instruction on a vmalloced/kmalloced/data page | |
94 | * is a recipe for disaster | |
95 | */ | |
96 | struct kprobe_insn_page { | |
97 | struct list_head list; | |
98 | kprobe_opcode_t *insns; /* Page of instruction slots */ | |
99 | struct kprobe_insn_cache *cache; | |
100 | int nused; | |
101 | int ngarbage; | |
102 | char slot_used[]; | |
103 | }; | |
104 | ||
105 | #define KPROBE_INSN_PAGE_SIZE(slots) \ | |
106 | (offsetof(struct kprobe_insn_page, slot_used) + \ | |
107 | (sizeof(char) * (slots))) | |
108 | ||
109 | static int slots_per_page(struct kprobe_insn_cache *c) | |
110 | { | |
111 | return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t)); | |
112 | } | |
113 | ||
114 | enum kprobe_slot_state { | |
115 | SLOT_CLEAN = 0, | |
116 | SLOT_DIRTY = 1, | |
117 | SLOT_USED = 2, | |
118 | }; | |
119 | ||
120 | void __weak *alloc_insn_page(void) | |
121 | { | |
122 | return module_alloc(PAGE_SIZE); | |
123 | } | |
124 | ||
125 | void __weak free_insn_page(void *page) | |
126 | { | |
127 | module_memfree(page); | |
128 | } | |
129 | ||
130 | struct kprobe_insn_cache kprobe_insn_slots = { | |
131 | .mutex = __MUTEX_INITIALIZER(kprobe_insn_slots.mutex), | |
132 | .alloc = alloc_insn_page, | |
133 | .free = free_insn_page, | |
134 | .pages = LIST_HEAD_INIT(kprobe_insn_slots.pages), | |
135 | .insn_size = MAX_INSN_SIZE, | |
136 | .nr_garbage = 0, | |
137 | }; | |
138 | static 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 | */ | |
144 | kprobe_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 | for (i = 0; i < slots_per_page(c); i++) { | |
157 | if (kip->slot_used[i] == SLOT_CLEAN) { | |
158 | kip->slot_used[i] = SLOT_USED; | |
159 | kip->nused++; | |
160 | slot = kip->insns + (i * c->insn_size); | |
161 | rcu_read_unlock(); | |
162 | goto out; | |
163 | } | |
164 | } | |
165 | /* kip->nused is broken. Fix it. */ | |
166 | kip->nused = slots_per_page(c); | |
167 | WARN_ON(1); | |
168 | } | |
169 | } | |
170 | rcu_read_unlock(); | |
171 | ||
172 | /* If there are any garbage slots, collect it and try again. */ | |
173 | if (c->nr_garbage && collect_garbage_slots(c) == 0) | |
174 | goto retry; | |
175 | ||
176 | /* All out of space. Need to allocate a new page. */ | |
177 | kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL); | |
178 | if (!kip) | |
179 | goto out; | |
180 | ||
181 | /* | |
182 | * Use module_alloc so this page is within +/- 2GB of where the | |
183 | * kernel image and loaded module images reside. This is required | |
184 | * so x86_64 can correctly handle the %rip-relative fixups. | |
185 | */ | |
186 | kip->insns = c->alloc(); | |
187 | if (!kip->insns) { | |
188 | kfree(kip); | |
189 | goto out; | |
190 | } | |
191 | INIT_LIST_HEAD(&kip->list); | |
192 | memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c)); | |
193 | kip->slot_used[0] = SLOT_USED; | |
194 | kip->nused = 1; | |
195 | kip->ngarbage = 0; | |
196 | kip->cache = c; | |
197 | list_add_rcu(&kip->list, &c->pages); | |
198 | slot = kip->insns; | |
199 | out: | |
200 | mutex_unlock(&c->mutex); | |
201 | return slot; | |
202 | } | |
203 | ||
204 | /* Return 1 if all garbages are collected, otherwise 0. */ | |
205 | static int 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 | list_del_rcu(&kip->list); | |
218 | synchronize_rcu(); | |
219 | kip->cache->free(kip->insns); | |
220 | kfree(kip); | |
221 | } | |
222 | return 1; | |
223 | } | |
224 | return 0; | |
225 | } | |
226 | ||
227 | static int collect_garbage_slots(struct kprobe_insn_cache *c) | |
228 | { | |
229 | struct kprobe_insn_page *kip, *next; | |
230 | ||
231 | /* Ensure no-one is interrupted on the garbages */ | |
232 | synchronize_sched(); | |
233 | ||
234 | list_for_each_entry_safe(kip, next, &c->pages, list) { | |
235 | int i; | |
236 | if (kip->ngarbage == 0) | |
237 | continue; | |
238 | kip->ngarbage = 0; /* we will collect all garbages */ | |
239 | for (i = 0; i < slots_per_page(c); i++) { | |
240 | if (kip->slot_used[i] == SLOT_DIRTY && collect_one_slot(kip, i)) | |
241 | break; | |
242 | } | |
243 | } | |
244 | c->nr_garbage = 0; | |
245 | return 0; | |
246 | } | |
247 | ||
248 | void __free_insn_slot(struct kprobe_insn_cache *c, | |
249 | kprobe_opcode_t *slot, int dirty) | |
250 | { | |
251 | struct kprobe_insn_page *kip; | |
252 | long idx; | |
253 | ||
254 | mutex_lock(&c->mutex); | |
255 | rcu_read_lock(); | |
256 | list_for_each_entry_rcu(kip, &c->pages, list) { | |
257 | idx = ((long)slot - (long)kip->insns) / | |
258 | (c->insn_size * sizeof(kprobe_opcode_t)); | |
259 | if (idx >= 0 && idx < slots_per_page(c)) | |
260 | goto out; | |
261 | } | |
262 | /* Could not find this slot. */ | |
263 | WARN_ON(1); | |
264 | kip = NULL; | |
265 | out: | |
266 | rcu_read_unlock(); | |
267 | /* Mark and sweep: this may sleep */ | |
268 | if (kip) { | |
269 | /* Check double free */ | |
270 | WARN_ON(kip->slot_used[idx] != SLOT_USED); | |
271 | if (dirty) { | |
272 | kip->slot_used[idx] = SLOT_DIRTY; | |
273 | kip->ngarbage++; | |
274 | if (++c->nr_garbage > slots_per_page(c)) | |
275 | collect_garbage_slots(c); | |
276 | } else { | |
277 | collect_one_slot(kip, idx); | |
278 | } | |
279 | } | |
280 | mutex_unlock(&c->mutex); | |
281 | } | |
282 | ||
283 | /* | |
284 | * Check given address is on the page of kprobe instruction slots. | |
285 | * This will be used for checking whether the address on a stack | |
286 | * is on a text area or not. | |
287 | */ | |
288 | bool __is_insn_slot_addr(struct kprobe_insn_cache *c, unsigned long addr) | |
289 | { | |
290 | struct kprobe_insn_page *kip; | |
291 | bool ret = false; | |
292 | ||
293 | rcu_read_lock(); | |
294 | list_for_each_entry_rcu(kip, &c->pages, list) { | |
295 | if (addr >= (unsigned long)kip->insns && | |
296 | addr < (unsigned long)kip->insns + PAGE_SIZE) { | |
297 | ret = true; | |
298 | break; | |
299 | } | |
300 | } | |
301 | rcu_read_unlock(); | |
302 | ||
303 | return ret; | |
304 | } | |
305 | ||
306 | #ifdef CONFIG_OPTPROBES | |
307 | /* For optimized_kprobe buffer */ | |
308 | struct kprobe_insn_cache kprobe_optinsn_slots = { | |
309 | .mutex = __MUTEX_INITIALIZER(kprobe_optinsn_slots.mutex), | |
310 | .alloc = alloc_insn_page, | |
311 | .free = free_insn_page, | |
312 | .pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages), | |
313 | /* .insn_size is initialized later */ | |
314 | .nr_garbage = 0, | |
315 | }; | |
316 | #endif | |
317 | #endif | |
318 | ||
319 | /* We have preemption disabled.. so it is safe to use __ versions */ | |
320 | static inline void set_kprobe_instance(struct kprobe *kp) | |
321 | { | |
322 | __this_cpu_write(kprobe_instance, kp); | |
323 | } | |
324 | ||
325 | static inline void reset_kprobe_instance(void) | |
326 | { | |
327 | __this_cpu_write(kprobe_instance, NULL); | |
328 | } | |
329 | ||
330 | /* | |
331 | * This routine is called either: | |
332 | * - under the kprobe_mutex - during kprobe_[un]register() | |
333 | * OR | |
334 | * - with preemption disabled - from arch/xxx/kernel/kprobes.c | |
335 | */ | |
336 | struct kprobe *get_kprobe(void *addr) | |
337 | { | |
338 | struct hlist_head *head; | |
339 | struct kprobe *p; | |
340 | ||
341 | head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)]; | |
342 | hlist_for_each_entry_rcu(p, head, hlist) { | |
343 | if (p->addr == addr) | |
344 | return p; | |
345 | } | |
346 | ||
347 | return NULL; | |
348 | } | |
349 | NOKPROBE_SYMBOL(get_kprobe); | |
350 | ||
351 | static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs); | |
352 | ||
353 | /* Return true if the kprobe is an aggregator */ | |
354 | static inline int kprobe_aggrprobe(struct kprobe *p) | |
355 | { | |
356 | return p->pre_handler == aggr_pre_handler; | |
357 | } | |
358 | ||
359 | /* Return true(!0) if the kprobe is unused */ | |
360 | static inline int kprobe_unused(struct kprobe *p) | |
361 | { | |
362 | return kprobe_aggrprobe(p) && kprobe_disabled(p) && | |
363 | list_empty(&p->list); | |
364 | } | |
365 | ||
366 | /* | |
367 | * Keep all fields in the kprobe consistent | |
368 | */ | |
369 | static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p) | |
370 | { | |
371 | memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t)); | |
372 | memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn)); | |
373 | } | |
374 | ||
375 | #ifdef CONFIG_OPTPROBES | |
376 | /* NOTE: change this value only with kprobe_mutex held */ | |
377 | static bool kprobes_allow_optimization; | |
378 | ||
379 | /* | |
380 | * Call all pre_handler on the list, but ignores its return value. | |
381 | * This must be called from arch-dep optimized caller. | |
382 | */ | |
383 | void opt_pre_handler(struct kprobe *p, struct pt_regs *regs) | |
384 | { | |
385 | struct kprobe *kp; | |
386 | ||
387 | list_for_each_entry_rcu(kp, &p->list, list) { | |
388 | if (kp->pre_handler && likely(!kprobe_disabled(kp))) { | |
389 | set_kprobe_instance(kp); | |
390 | kp->pre_handler(kp, regs); | |
391 | } | |
392 | reset_kprobe_instance(); | |
393 | } | |
394 | } | |
395 | NOKPROBE_SYMBOL(opt_pre_handler); | |
396 | ||
397 | /* Free optimized instructions and optimized_kprobe */ | |
398 | static void free_aggr_kprobe(struct kprobe *p) | |
399 | { | |
400 | struct optimized_kprobe *op; | |
401 | ||
402 | op = container_of(p, struct optimized_kprobe, kp); | |
403 | arch_remove_optimized_kprobe(op); | |
404 | arch_remove_kprobe(p); | |
405 | kfree(op); | |
406 | } | |
407 | ||
408 | /* Return true(!0) if the kprobe is ready for optimization. */ | |
409 | static inline int kprobe_optready(struct kprobe *p) | |
410 | { | |
411 | struct optimized_kprobe *op; | |
412 | ||
413 | if (kprobe_aggrprobe(p)) { | |
414 | op = container_of(p, struct optimized_kprobe, kp); | |
415 | return arch_prepared_optinsn(&op->optinsn); | |
416 | } | |
417 | ||
418 | return 0; | |
419 | } | |
420 | ||
421 | /* Return true(!0) if the kprobe is disarmed. Note: p must be on hash list */ | |
422 | static inline int kprobe_disarmed(struct kprobe *p) | |
423 | { | |
424 | struct optimized_kprobe *op; | |
425 | ||
426 | /* If kprobe is not aggr/opt probe, just return kprobe is disabled */ | |
427 | if (!kprobe_aggrprobe(p)) | |
428 | return kprobe_disabled(p); | |
429 | ||
430 | op = container_of(p, struct optimized_kprobe, kp); | |
431 | ||
432 | return kprobe_disabled(p) && list_empty(&op->list); | |
433 | } | |
434 | ||
435 | /* Return true(!0) if the probe is queued on (un)optimizing lists */ | |
436 | static int kprobe_queued(struct kprobe *p) | |
437 | { | |
438 | struct optimized_kprobe *op; | |
439 | ||
440 | if (kprobe_aggrprobe(p)) { | |
441 | op = container_of(p, struct optimized_kprobe, kp); | |
442 | if (!list_empty(&op->list)) | |
443 | return 1; | |
444 | } | |
445 | return 0; | |
446 | } | |
447 | ||
448 | /* | |
449 | * Return an optimized kprobe whose optimizing code replaces | |
450 | * instructions including addr (exclude breakpoint). | |
451 | */ | |
452 | static struct kprobe *get_optimized_kprobe(unsigned long addr) | |
453 | { | |
454 | int i; | |
455 | struct kprobe *p = NULL; | |
456 | struct optimized_kprobe *op; | |
457 | ||
458 | /* Don't check i == 0, since that is a breakpoint case. */ | |
459 | for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH; i++) | |
460 | p = get_kprobe((void *)(addr - i)); | |
461 | ||
462 | if (p && kprobe_optready(p)) { | |
463 | op = container_of(p, struct optimized_kprobe, kp); | |
464 | if (arch_within_optimized_kprobe(op, addr)) | |
465 | return p; | |
466 | } | |
467 | ||
468 | return NULL; | |
469 | } | |
470 | ||
471 | /* Optimization staging list, protected by kprobe_mutex */ | |
472 | static LIST_HEAD(optimizing_list); | |
473 | static LIST_HEAD(unoptimizing_list); | |
474 | static LIST_HEAD(freeing_list); | |
475 | ||
476 | static void kprobe_optimizer(struct work_struct *work); | |
477 | static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer); | |
478 | #define OPTIMIZE_DELAY 5 | |
479 | ||
480 | /* | |
481 | * Optimize (replace a breakpoint with a jump) kprobes listed on | |
482 | * optimizing_list. | |
483 | */ | |
484 | static void do_optimize_kprobes(void) | |
485 | { | |
486 | lockdep_assert_held(&text_mutex); | |
487 | /* | |
488 | * The optimization/unoptimization refers online_cpus via | |
489 | * stop_machine() and cpu-hotplug modifies online_cpus. | |
490 | * And same time, text_mutex will be held in cpu-hotplug and here. | |
491 | * This combination can cause a deadlock (cpu-hotplug try to lock | |
492 | * text_mutex but stop_machine can not be done because online_cpus | |
493 | * has been changed) | |
494 | * To avoid this deadlock, caller must have locked cpu hotplug | |
495 | * for preventing cpu-hotplug outside of text_mutex locking. | |
496 | */ | |
497 | lockdep_assert_cpus_held(); | |
498 | ||
499 | /* Optimization never be done when disarmed */ | |
500 | if (kprobes_all_disarmed || !kprobes_allow_optimization || | |
501 | list_empty(&optimizing_list)) | |
502 | return; | |
503 | ||
504 | arch_optimize_kprobes(&optimizing_list); | |
505 | } | |
506 | ||
507 | /* | |
508 | * Unoptimize (replace a jump with a breakpoint and remove the breakpoint | |
509 | * if need) kprobes listed on unoptimizing_list. | |
510 | */ | |
511 | static void do_unoptimize_kprobes(void) | |
512 | { | |
513 | struct optimized_kprobe *op, *tmp; | |
514 | ||
515 | lockdep_assert_held(&text_mutex); | |
516 | /* See comment in do_optimize_kprobes() */ | |
517 | lockdep_assert_cpus_held(); | |
518 | ||
519 | /* Unoptimization must be done anytime */ | |
520 | if (list_empty(&unoptimizing_list)) | |
521 | return; | |
522 | ||
523 | arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list); | |
524 | /* Loop free_list for disarming */ | |
525 | list_for_each_entry_safe(op, tmp, &freeing_list, list) { | |
526 | /* Disarm probes if marked disabled */ | |
527 | if (kprobe_disabled(&op->kp)) | |
528 | arch_disarm_kprobe(&op->kp); | |
529 | if (kprobe_unused(&op->kp)) { | |
530 | /* | |
531 | * Remove unused probes from hash list. After waiting | |
532 | * for synchronization, these probes are reclaimed. | |
533 | * (reclaiming is done by do_free_cleaned_kprobes.) | |
534 | */ | |
535 | hlist_del_rcu(&op->kp.hlist); | |
536 | } else | |
537 | list_del_init(&op->list); | |
538 | } | |
539 | } | |
540 | ||
541 | /* Reclaim all kprobes on the free_list */ | |
542 | static void do_free_cleaned_kprobes(void) | |
543 | { | |
544 | struct optimized_kprobe *op, *tmp; | |
545 | ||
546 | list_for_each_entry_safe(op, tmp, &freeing_list, list) { | |
547 | list_del_init(&op->list); | |
548 | if (WARN_ON_ONCE(!kprobe_unused(&op->kp))) { | |
549 | /* | |
550 | * This must not happen, but if there is a kprobe | |
551 | * still in use, keep it on kprobes hash list. | |
552 | */ | |
553 | continue; | |
554 | } | |
555 | free_aggr_kprobe(&op->kp); | |
556 | } | |
557 | } | |
558 | ||
559 | /* Start optimizer after OPTIMIZE_DELAY passed */ | |
560 | static void kick_kprobe_optimizer(void) | |
561 | { | |
562 | schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY); | |
563 | } | |
564 | ||
565 | /* Kprobe jump optimizer */ | |
566 | static void kprobe_optimizer(struct work_struct *work) | |
567 | { | |
568 | mutex_lock(&kprobe_mutex); | |
569 | cpus_read_lock(); | |
570 | mutex_lock(&text_mutex); | |
571 | /* Lock modules while optimizing kprobes */ | |
572 | mutex_lock(&module_mutex); | |
573 | ||
574 | /* | |
575 | * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed) | |
576 | * kprobes before waiting for quiesence period. | |
577 | */ | |
578 | do_unoptimize_kprobes(); | |
579 | ||
580 | /* | |
581 | * Step 2: Wait for quiesence period to ensure all potentially | |
582 | * preempted tasks to have normally scheduled. Because optprobe | |
583 | * may modify multiple instructions, there is a chance that Nth | |
584 | * instruction is preempted. In that case, such tasks can return | |
585 | * to 2nd-Nth byte of jump instruction. This wait is for avoiding it. | |
586 | * Note that on non-preemptive kernel, this is transparently converted | |
587 | * to synchronoze_sched() to wait for all interrupts to have completed. | |
588 | */ | |
589 | synchronize_rcu_tasks(); | |
590 | ||
591 | /* Step 3: Optimize kprobes after quiesence period */ | |
592 | do_optimize_kprobes(); | |
593 | ||
594 | /* Step 4: Free cleaned kprobes after quiesence period */ | |
595 | do_free_cleaned_kprobes(); | |
596 | ||
597 | mutex_unlock(&module_mutex); | |
598 | mutex_unlock(&text_mutex); | |
599 | cpus_read_unlock(); | |
600 | mutex_unlock(&kprobe_mutex); | |
601 | ||
602 | /* Step 5: Kick optimizer again if needed */ | |
603 | if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) | |
604 | kick_kprobe_optimizer(); | |
605 | } | |
606 | ||
607 | /* Wait for completing optimization and unoptimization */ | |
608 | void wait_for_kprobe_optimizer(void) | |
609 | { | |
610 | mutex_lock(&kprobe_mutex); | |
611 | ||
612 | while (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) { | |
613 | mutex_unlock(&kprobe_mutex); | |
614 | ||
615 | /* this will also make optimizing_work execute immmediately */ | |
616 | flush_delayed_work(&optimizing_work); | |
617 | /* @optimizing_work might not have been queued yet, relax */ | |
618 | cpu_relax(); | |
619 | ||
620 | mutex_lock(&kprobe_mutex); | |
621 | } | |
622 | ||
623 | mutex_unlock(&kprobe_mutex); | |
624 | } | |
625 | ||
626 | /* Optimize kprobe if p is ready to be optimized */ | |
627 | static void optimize_kprobe(struct kprobe *p) | |
628 | { | |
629 | struct optimized_kprobe *op; | |
630 | ||
631 | /* Check if the kprobe is disabled or not ready for optimization. */ | |
632 | if (!kprobe_optready(p) || !kprobes_allow_optimization || | |
633 | (kprobe_disabled(p) || kprobes_all_disarmed)) | |
634 | return; | |
635 | ||
636 | /* Both of break_handler and post_handler are not supported. */ | |
637 | if (p->break_handler || p->post_handler) | |
638 | return; | |
639 | ||
640 | op = container_of(p, struct optimized_kprobe, kp); | |
641 | ||
642 | /* Check there is no other kprobes at the optimized instructions */ | |
643 | if (arch_check_optimized_kprobe(op) < 0) | |
644 | return; | |
645 | ||
646 | /* Check if it is already optimized. */ | |
647 | if (op->kp.flags & KPROBE_FLAG_OPTIMIZED) | |
648 | return; | |
649 | op->kp.flags |= KPROBE_FLAG_OPTIMIZED; | |
650 | ||
651 | if (!list_empty(&op->list)) | |
652 | /* This is under unoptimizing. Just dequeue the probe */ | |
653 | list_del_init(&op->list); | |
654 | else { | |
655 | list_add(&op->list, &optimizing_list); | |
656 | kick_kprobe_optimizer(); | |
657 | } | |
658 | } | |
659 | ||
660 | /* Short cut to direct unoptimizing */ | |
661 | static void force_unoptimize_kprobe(struct optimized_kprobe *op) | |
662 | { | |
663 | lockdep_assert_cpus_held(); | |
664 | arch_unoptimize_kprobe(op); | |
665 | if (kprobe_disabled(&op->kp)) | |
666 | arch_disarm_kprobe(&op->kp); | |
667 | } | |
668 | ||
669 | /* Unoptimize a kprobe if p is optimized */ | |
670 | static void unoptimize_kprobe(struct kprobe *p, bool force) | |
671 | { | |
672 | struct optimized_kprobe *op; | |
673 | ||
674 | if (!kprobe_aggrprobe(p) || kprobe_disarmed(p)) | |
675 | return; /* This is not an optprobe nor optimized */ | |
676 | ||
677 | op = container_of(p, struct optimized_kprobe, kp); | |
678 | if (!kprobe_optimized(p)) { | |
679 | /* Unoptimized or unoptimizing case */ | |
680 | if (force && !list_empty(&op->list)) { | |
681 | /* | |
682 | * Only if this is unoptimizing kprobe and forced, | |
683 | * forcibly unoptimize it. (No need to unoptimize | |
684 | * unoptimized kprobe again :) | |
685 | */ | |
686 | list_del_init(&op->list); | |
687 | force_unoptimize_kprobe(op); | |
688 | } | |
689 | return; | |
690 | } | |
691 | ||
692 | op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED; | |
693 | if (!list_empty(&op->list)) { | |
694 | /* Dequeue from the optimization queue */ | |
695 | list_del_init(&op->list); | |
696 | return; | |
697 | } | |
698 | /* Optimized kprobe case */ | |
699 | if (force) | |
700 | /* Forcibly update the code: this is a special case */ | |
701 | force_unoptimize_kprobe(op); | |
702 | else { | |
703 | list_add(&op->list, &unoptimizing_list); | |
704 | kick_kprobe_optimizer(); | |
705 | } | |
706 | } | |
707 | ||
708 | /* Cancel unoptimizing for reusing */ | |
709 | static int reuse_unused_kprobe(struct kprobe *ap) | |
710 | { | |
711 | struct optimized_kprobe *op; | |
712 | ||
713 | BUG_ON(!kprobe_unused(ap)); | |
714 | /* | |
715 | * Unused kprobe MUST be on the way of delayed unoptimizing (means | |
716 | * there is still a relative jump) and disabled. | |
717 | */ | |
718 | op = container_of(ap, struct optimized_kprobe, kp); | |
719 | WARN_ON_ONCE(list_empty(&op->list)); | |
720 | /* Enable the probe again */ | |
721 | ap->flags &= ~KPROBE_FLAG_DISABLED; | |
722 | /* Optimize it again (remove from op->list) */ | |
723 | if (!kprobe_optready(ap)) | |
724 | return -EINVAL; | |
725 | ||
726 | optimize_kprobe(ap); | |
727 | return 0; | |
728 | } | |
729 | ||
730 | /* Remove optimized instructions */ | |
731 | static void kill_optimized_kprobe(struct kprobe *p) | |
732 | { | |
733 | struct optimized_kprobe *op; | |
734 | ||
735 | op = container_of(p, struct optimized_kprobe, kp); | |
736 | if (!list_empty(&op->list)) | |
737 | /* Dequeue from the (un)optimization queue */ | |
738 | list_del_init(&op->list); | |
739 | op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED; | |
740 | ||
741 | if (kprobe_unused(p)) { | |
742 | /* Enqueue if it is unused */ | |
743 | list_add(&op->list, &freeing_list); | |
744 | /* | |
745 | * Remove unused probes from the hash list. After waiting | |
746 | * for synchronization, this probe is reclaimed. | |
747 | * (reclaiming is done by do_free_cleaned_kprobes().) | |
748 | */ | |
749 | hlist_del_rcu(&op->kp.hlist); | |
750 | } | |
751 | ||
752 | /* Don't touch the code, because it is already freed. */ | |
753 | arch_remove_optimized_kprobe(op); | |
754 | } | |
755 | ||
756 | static inline | |
757 | void __prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p) | |
758 | { | |
759 | if (!kprobe_ftrace(p)) | |
760 | arch_prepare_optimized_kprobe(op, p); | |
761 | } | |
762 | ||
763 | /* Try to prepare optimized instructions */ | |
764 | static void prepare_optimized_kprobe(struct kprobe *p) | |
765 | { | |
766 | struct optimized_kprobe *op; | |
767 | ||
768 | op = container_of(p, struct optimized_kprobe, kp); | |
769 | __prepare_optimized_kprobe(op, p); | |
770 | } | |
771 | ||
772 | /* Allocate new optimized_kprobe and try to prepare optimized instructions */ | |
773 | static struct kprobe *alloc_aggr_kprobe(struct kprobe *p) | |
774 | { | |
775 | struct optimized_kprobe *op; | |
776 | ||
777 | op = kzalloc(sizeof(struct optimized_kprobe), GFP_KERNEL); | |
778 | if (!op) | |
779 | return NULL; | |
780 | ||
781 | INIT_LIST_HEAD(&op->list); | |
782 | op->kp.addr = p->addr; | |
783 | __prepare_optimized_kprobe(op, p); | |
784 | ||
785 | return &op->kp; | |
786 | } | |
787 | ||
788 | static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p); | |
789 | ||
790 | /* | |
791 | * Prepare an optimized_kprobe and optimize it | |
792 | * NOTE: p must be a normal registered kprobe | |
793 | */ | |
794 | static void try_to_optimize_kprobe(struct kprobe *p) | |
795 | { | |
796 | struct kprobe *ap; | |
797 | struct optimized_kprobe *op; | |
798 | ||
799 | /* Impossible to optimize ftrace-based kprobe */ | |
800 | if (kprobe_ftrace(p)) | |
801 | return; | |
802 | ||
803 | /* For preparing optimization, jump_label_text_reserved() is called */ | |
804 | cpus_read_lock(); | |
805 | jump_label_lock(); | |
806 | mutex_lock(&text_mutex); | |
807 | ||
808 | ap = alloc_aggr_kprobe(p); | |
809 | if (!ap) | |
810 | goto out; | |
811 | ||
812 | op = container_of(ap, struct optimized_kprobe, kp); | |
813 | if (!arch_prepared_optinsn(&op->optinsn)) { | |
814 | /* If failed to setup optimizing, fallback to kprobe */ | |
815 | arch_remove_optimized_kprobe(op); | |
816 | kfree(op); | |
817 | goto out; | |
818 | } | |
819 | ||
820 | init_aggr_kprobe(ap, p); | |
821 | optimize_kprobe(ap); /* This just kicks optimizer thread */ | |
822 | ||
823 | out: | |
824 | mutex_unlock(&text_mutex); | |
825 | jump_label_unlock(); | |
826 | cpus_read_unlock(); | |
827 | } | |
828 | ||
829 | #ifdef CONFIG_SYSCTL | |
830 | static void optimize_all_kprobes(void) | |
831 | { | |
832 | struct hlist_head *head; | |
833 | struct kprobe *p; | |
834 | unsigned int i; | |
835 | ||
836 | mutex_lock(&kprobe_mutex); | |
837 | /* If optimization is already allowed, just return */ | |
838 | if (kprobes_allow_optimization) | |
839 | goto out; | |
840 | ||
841 | cpus_read_lock(); | |
842 | kprobes_allow_optimization = true; | |
843 | for (i = 0; i < KPROBE_TABLE_SIZE; i++) { | |
844 | head = &kprobe_table[i]; | |
845 | hlist_for_each_entry_rcu(p, head, hlist) | |
846 | if (!kprobe_disabled(p)) | |
847 | optimize_kprobe(p); | |
848 | } | |
849 | cpus_read_unlock(); | |
850 | printk(KERN_INFO "Kprobes globally optimized\n"); | |
851 | out: | |
852 | mutex_unlock(&kprobe_mutex); | |
853 | } | |
854 | ||
855 | static void unoptimize_all_kprobes(void) | |
856 | { | |
857 | struct hlist_head *head; | |
858 | struct kprobe *p; | |
859 | unsigned int i; | |
860 | ||
861 | mutex_lock(&kprobe_mutex); | |
862 | /* If optimization is already prohibited, just return */ | |
863 | if (!kprobes_allow_optimization) { | |
864 | mutex_unlock(&kprobe_mutex); | |
865 | return; | |
866 | } | |
867 | ||
868 | cpus_read_lock(); | |
869 | kprobes_allow_optimization = false; | |
870 | for (i = 0; i < KPROBE_TABLE_SIZE; i++) { | |
871 | head = &kprobe_table[i]; | |
872 | hlist_for_each_entry_rcu(p, head, hlist) { | |
873 | if (!kprobe_disabled(p)) | |
874 | unoptimize_kprobe(p, false); | |
875 | } | |
876 | } | |
877 | cpus_read_unlock(); | |
878 | mutex_unlock(&kprobe_mutex); | |
879 | ||
880 | /* Wait for unoptimizing completion */ | |
881 | wait_for_kprobe_optimizer(); | |
882 | printk(KERN_INFO "Kprobes globally unoptimized\n"); | |
883 | } | |
884 | ||
885 | static DEFINE_MUTEX(kprobe_sysctl_mutex); | |
886 | int sysctl_kprobes_optimization; | |
887 | int proc_kprobes_optimization_handler(struct ctl_table *table, int write, | |
888 | void __user *buffer, size_t *length, | |
889 | loff_t *ppos) | |
890 | { | |
891 | int ret; | |
892 | ||
893 | mutex_lock(&kprobe_sysctl_mutex); | |
894 | sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0; | |
895 | ret = proc_dointvec_minmax(table, write, buffer, length, ppos); | |
896 | ||
897 | if (sysctl_kprobes_optimization) | |
898 | optimize_all_kprobes(); | |
899 | else | |
900 | unoptimize_all_kprobes(); | |
901 | mutex_unlock(&kprobe_sysctl_mutex); | |
902 | ||
903 | return ret; | |
904 | } | |
905 | #endif /* CONFIG_SYSCTL */ | |
906 | ||
907 | /* Put a breakpoint for a probe. Must be called with text_mutex locked */ | |
908 | static void __arm_kprobe(struct kprobe *p) | |
909 | { | |
910 | struct kprobe *_p; | |
911 | ||
912 | /* Check collision with other optimized kprobes */ | |
913 | _p = get_optimized_kprobe((unsigned long)p->addr); | |
914 | if (unlikely(_p)) | |
915 | /* Fallback to unoptimized kprobe */ | |
916 | unoptimize_kprobe(_p, true); | |
917 | ||
918 | arch_arm_kprobe(p); | |
919 | optimize_kprobe(p); /* Try to optimize (add kprobe to a list) */ | |
920 | } | |
921 | ||
922 | /* Remove the breakpoint of a probe. Must be called with text_mutex locked */ | |
923 | static void __disarm_kprobe(struct kprobe *p, bool reopt) | |
924 | { | |
925 | struct kprobe *_p; | |
926 | ||
927 | /* Try to unoptimize */ | |
928 | unoptimize_kprobe(p, kprobes_all_disarmed); | |
929 | ||
930 | if (!kprobe_queued(p)) { | |
931 | arch_disarm_kprobe(p); | |
932 | /* If another kprobe was blocked, optimize it. */ | |
933 | _p = get_optimized_kprobe((unsigned long)p->addr); | |
934 | if (unlikely(_p) && reopt) | |
935 | optimize_kprobe(_p); | |
936 | } | |
937 | /* TODO: reoptimize others after unoptimized this probe */ | |
938 | } | |
939 | ||
940 | #else /* !CONFIG_OPTPROBES */ | |
941 | ||
942 | #define optimize_kprobe(p) do {} while (0) | |
943 | #define unoptimize_kprobe(p, f) do {} while (0) | |
944 | #define kill_optimized_kprobe(p) do {} while (0) | |
945 | #define prepare_optimized_kprobe(p) do {} while (0) | |
946 | #define try_to_optimize_kprobe(p) do {} while (0) | |
947 | #define __arm_kprobe(p) arch_arm_kprobe(p) | |
948 | #define __disarm_kprobe(p, o) arch_disarm_kprobe(p) | |
949 | #define kprobe_disarmed(p) kprobe_disabled(p) | |
950 | #define wait_for_kprobe_optimizer() do {} while (0) | |
951 | ||
952 | static int reuse_unused_kprobe(struct kprobe *ap) | |
953 | { | |
954 | /* | |
955 | * If the optimized kprobe is NOT supported, the aggr kprobe is | |
956 | * released at the same time that the last aggregated kprobe is | |
957 | * unregistered. | |
958 | * Thus there should be no chance to reuse unused kprobe. | |
959 | */ | |
960 | printk(KERN_ERR "Error: There should be no unused kprobe here.\n"); | |
961 | return -EINVAL; | |
962 | } | |
963 | ||
964 | static void free_aggr_kprobe(struct kprobe *p) | |
965 | { | |
966 | arch_remove_kprobe(p); | |
967 | kfree(p); | |
968 | } | |
969 | ||
970 | static struct kprobe *alloc_aggr_kprobe(struct kprobe *p) | |
971 | { | |
972 | return kzalloc(sizeof(struct kprobe), GFP_KERNEL); | |
973 | } | |
974 | #endif /* CONFIG_OPTPROBES */ | |
975 | ||
976 | #ifdef CONFIG_KPROBES_ON_FTRACE | |
977 | static struct ftrace_ops kprobe_ftrace_ops __read_mostly = { | |
978 | .func = kprobe_ftrace_handler, | |
979 | .flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_IPMODIFY, | |
980 | }; | |
981 | static int kprobe_ftrace_enabled; | |
982 | ||
983 | /* Must ensure p->addr is really on ftrace */ | |
984 | static int prepare_kprobe(struct kprobe *p) | |
985 | { | |
986 | if (!kprobe_ftrace(p)) | |
987 | return arch_prepare_kprobe(p); | |
988 | ||
989 | return arch_prepare_kprobe_ftrace(p); | |
990 | } | |
991 | ||
992 | /* Caller must lock kprobe_mutex */ | |
993 | static void arm_kprobe_ftrace(struct kprobe *p) | |
994 | { | |
995 | int ret; | |
996 | ||
997 | ret = ftrace_set_filter_ip(&kprobe_ftrace_ops, | |
998 | (unsigned long)p->addr, 0, 0); | |
999 | WARN(ret < 0, "Failed to arm kprobe-ftrace at %pS (%d)\n", p->addr, ret); | |
1000 | kprobe_ftrace_enabled++; | |
1001 | if (kprobe_ftrace_enabled == 1) { | |
1002 | ret = register_ftrace_function(&kprobe_ftrace_ops); | |
1003 | WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret); | |
1004 | } | |
1005 | } | |
1006 | ||
1007 | /* Caller must lock kprobe_mutex */ | |
1008 | static void disarm_kprobe_ftrace(struct kprobe *p) | |
1009 | { | |
1010 | int ret; | |
1011 | ||
1012 | kprobe_ftrace_enabled--; | |
1013 | if (kprobe_ftrace_enabled == 0) { | |
1014 | ret = unregister_ftrace_function(&kprobe_ftrace_ops); | |
1015 | WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret); | |
1016 | } | |
1017 | ret = ftrace_set_filter_ip(&kprobe_ftrace_ops, | |
1018 | (unsigned long)p->addr, 1, 0); | |
1019 | WARN(ret < 0, "Failed to disarm kprobe-ftrace at %pS (%d)\n", p->addr, ret); | |
1020 | } | |
1021 | #else /* !CONFIG_KPROBES_ON_FTRACE */ | |
1022 | #define prepare_kprobe(p) arch_prepare_kprobe(p) | |
1023 | #define arm_kprobe_ftrace(p) do {} while (0) | |
1024 | #define disarm_kprobe_ftrace(p) do {} while (0) | |
1025 | #endif | |
1026 | ||
1027 | /* Arm a kprobe with text_mutex */ | |
1028 | static void arm_kprobe(struct kprobe *kp) | |
1029 | { | |
1030 | if (unlikely(kprobe_ftrace(kp))) { | |
1031 | arm_kprobe_ftrace(kp); | |
1032 | return; | |
1033 | } | |
1034 | cpus_read_lock(); | |
1035 | mutex_lock(&text_mutex); | |
1036 | __arm_kprobe(kp); | |
1037 | mutex_unlock(&text_mutex); | |
1038 | cpus_read_unlock(); | |
1039 | } | |
1040 | ||
1041 | /* Disarm a kprobe with text_mutex */ | |
1042 | static void disarm_kprobe(struct kprobe *kp, bool reopt) | |
1043 | { | |
1044 | if (unlikely(kprobe_ftrace(kp))) { | |
1045 | disarm_kprobe_ftrace(kp); | |
1046 | return; | |
1047 | } | |
1048 | ||
1049 | cpus_read_lock(); | |
1050 | mutex_lock(&text_mutex); | |
1051 | __disarm_kprobe(kp, reopt); | |
1052 | mutex_unlock(&text_mutex); | |
1053 | cpus_read_unlock(); | |
1054 | } | |
1055 | ||
1056 | /* | |
1057 | * Aggregate handlers for multiple kprobes support - these handlers | |
1058 | * take care of invoking the individual kprobe handlers on p->list | |
1059 | */ | |
1060 | static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs) | |
1061 | { | |
1062 | struct kprobe *kp; | |
1063 | ||
1064 | list_for_each_entry_rcu(kp, &p->list, list) { | |
1065 | if (kp->pre_handler && likely(!kprobe_disabled(kp))) { | |
1066 | set_kprobe_instance(kp); | |
1067 | if (kp->pre_handler(kp, regs)) | |
1068 | return 1; | |
1069 | } | |
1070 | reset_kprobe_instance(); | |
1071 | } | |
1072 | return 0; | |
1073 | } | |
1074 | NOKPROBE_SYMBOL(aggr_pre_handler); | |
1075 | ||
1076 | static void aggr_post_handler(struct kprobe *p, struct pt_regs *regs, | |
1077 | unsigned long flags) | |
1078 | { | |
1079 | struct kprobe *kp; | |
1080 | ||
1081 | list_for_each_entry_rcu(kp, &p->list, list) { | |
1082 | if (kp->post_handler && likely(!kprobe_disabled(kp))) { | |
1083 | set_kprobe_instance(kp); | |
1084 | kp->post_handler(kp, regs, flags); | |
1085 | reset_kprobe_instance(); | |
1086 | } | |
1087 | } | |
1088 | } | |
1089 | NOKPROBE_SYMBOL(aggr_post_handler); | |
1090 | ||
1091 | static int aggr_fault_handler(struct kprobe *p, struct pt_regs *regs, | |
1092 | int trapnr) | |
1093 | { | |
1094 | struct kprobe *cur = __this_cpu_read(kprobe_instance); | |
1095 | ||
1096 | /* | |
1097 | * if we faulted "during" the execution of a user specified | |
1098 | * probe handler, invoke just that probe's fault handler | |
1099 | */ | |
1100 | if (cur && cur->fault_handler) { | |
1101 | if (cur->fault_handler(cur, regs, trapnr)) | |
1102 | return 1; | |
1103 | } | |
1104 | return 0; | |
1105 | } | |
1106 | NOKPROBE_SYMBOL(aggr_fault_handler); | |
1107 | ||
1108 | static int aggr_break_handler(struct kprobe *p, struct pt_regs *regs) | |
1109 | { | |
1110 | struct kprobe *cur = __this_cpu_read(kprobe_instance); | |
1111 | int ret = 0; | |
1112 | ||
1113 | if (cur && cur->break_handler) { | |
1114 | if (cur->break_handler(cur, regs)) | |
1115 | ret = 1; | |
1116 | } | |
1117 | reset_kprobe_instance(); | |
1118 | return ret; | |
1119 | } | |
1120 | NOKPROBE_SYMBOL(aggr_break_handler); | |
1121 | ||
1122 | /* Walks the list and increments nmissed count for multiprobe case */ | |
1123 | void kprobes_inc_nmissed_count(struct kprobe *p) | |
1124 | { | |
1125 | struct kprobe *kp; | |
1126 | if (!kprobe_aggrprobe(p)) { | |
1127 | p->nmissed++; | |
1128 | } else { | |
1129 | list_for_each_entry_rcu(kp, &p->list, list) | |
1130 | kp->nmissed++; | |
1131 | } | |
1132 | return; | |
1133 | } | |
1134 | NOKPROBE_SYMBOL(kprobes_inc_nmissed_count); | |
1135 | ||
1136 | void recycle_rp_inst(struct kretprobe_instance *ri, | |
1137 | struct hlist_head *head) | |
1138 | { | |
1139 | struct kretprobe *rp = ri->rp; | |
1140 | ||
1141 | /* remove rp inst off the rprobe_inst_table */ | |
1142 | hlist_del(&ri->hlist); | |
1143 | INIT_HLIST_NODE(&ri->hlist); | |
1144 | if (likely(rp)) { | |
1145 | raw_spin_lock(&rp->lock); | |
1146 | hlist_add_head(&ri->hlist, &rp->free_instances); | |
1147 | raw_spin_unlock(&rp->lock); | |
1148 | } else | |
1149 | /* Unregistering */ | |
1150 | hlist_add_head(&ri->hlist, head); | |
1151 | } | |
1152 | NOKPROBE_SYMBOL(recycle_rp_inst); | |
1153 | ||
1154 | void kretprobe_hash_lock(struct task_struct *tsk, | |
1155 | struct hlist_head **head, unsigned long *flags) | |
1156 | __acquires(hlist_lock) | |
1157 | { | |
1158 | unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS); | |
1159 | raw_spinlock_t *hlist_lock; | |
1160 | ||
1161 | *head = &kretprobe_inst_table[hash]; | |
1162 | hlist_lock = kretprobe_table_lock_ptr(hash); | |
1163 | raw_spin_lock_irqsave(hlist_lock, *flags); | |
1164 | } | |
1165 | NOKPROBE_SYMBOL(kretprobe_hash_lock); | |
1166 | ||
1167 | static void kretprobe_table_lock(unsigned long hash, | |
1168 | unsigned long *flags) | |
1169 | __acquires(hlist_lock) | |
1170 | { | |
1171 | raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash); | |
1172 | raw_spin_lock_irqsave(hlist_lock, *flags); | |
1173 | } | |
1174 | NOKPROBE_SYMBOL(kretprobe_table_lock); | |
1175 | ||
1176 | void kretprobe_hash_unlock(struct task_struct *tsk, | |
1177 | unsigned long *flags) | |
1178 | __releases(hlist_lock) | |
1179 | { | |
1180 | unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS); | |
1181 | raw_spinlock_t *hlist_lock; | |
1182 | ||
1183 | hlist_lock = kretprobe_table_lock_ptr(hash); | |
1184 | raw_spin_unlock_irqrestore(hlist_lock, *flags); | |
1185 | } | |
1186 | NOKPROBE_SYMBOL(kretprobe_hash_unlock); | |
1187 | ||
1188 | static void kretprobe_table_unlock(unsigned long hash, | |
1189 | unsigned long *flags) | |
1190 | __releases(hlist_lock) | |
1191 | { | |
1192 | raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash); | |
1193 | raw_spin_unlock_irqrestore(hlist_lock, *flags); | |
1194 | } | |
1195 | NOKPROBE_SYMBOL(kretprobe_table_unlock); | |
1196 | ||
1197 | /* | |
1198 | * This function is called from finish_task_switch when task tk becomes dead, | |
1199 | * so that we can recycle any function-return probe instances associated | |
1200 | * with this task. These left over instances represent probed functions | |
1201 | * that have been called but will never return. | |
1202 | */ | |
1203 | void kprobe_flush_task(struct task_struct *tk) | |
1204 | { | |
1205 | struct kretprobe_instance *ri; | |
1206 | struct hlist_head *head, empty_rp; | |
1207 | struct hlist_node *tmp; | |
1208 | unsigned long hash, flags = 0; | |
1209 | ||
1210 | if (unlikely(!kprobes_initialized)) | |
1211 | /* Early boot. kretprobe_table_locks not yet initialized. */ | |
1212 | return; | |
1213 | ||
1214 | INIT_HLIST_HEAD(&empty_rp); | |
1215 | hash = hash_ptr(tk, KPROBE_HASH_BITS); | |
1216 | head = &kretprobe_inst_table[hash]; | |
1217 | kretprobe_table_lock(hash, &flags); | |
1218 | hlist_for_each_entry_safe(ri, tmp, head, hlist) { | |
1219 | if (ri->task == tk) | |
1220 | recycle_rp_inst(ri, &empty_rp); | |
1221 | } | |
1222 | kretprobe_table_unlock(hash, &flags); | |
1223 | hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { | |
1224 | hlist_del(&ri->hlist); | |
1225 | kfree(ri); | |
1226 | } | |
1227 | } | |
1228 | NOKPROBE_SYMBOL(kprobe_flush_task); | |
1229 | ||
1230 | static inline void free_rp_inst(struct kretprobe *rp) | |
1231 | { | |
1232 | struct kretprobe_instance *ri; | |
1233 | struct hlist_node *next; | |
1234 | ||
1235 | hlist_for_each_entry_safe(ri, next, &rp->free_instances, hlist) { | |
1236 | hlist_del(&ri->hlist); | |
1237 | kfree(ri); | |
1238 | } | |
1239 | } | |
1240 | ||
1241 | static void cleanup_rp_inst(struct kretprobe *rp) | |
1242 | { | |
1243 | unsigned long flags, hash; | |
1244 | struct kretprobe_instance *ri; | |
1245 | struct hlist_node *next; | |
1246 | struct hlist_head *head; | |
1247 | ||
1248 | /* No race here */ | |
1249 | for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) { | |
1250 | kretprobe_table_lock(hash, &flags); | |
1251 | head = &kretprobe_inst_table[hash]; | |
1252 | hlist_for_each_entry_safe(ri, next, head, hlist) { | |
1253 | if (ri->rp == rp) | |
1254 | ri->rp = NULL; | |
1255 | } | |
1256 | kretprobe_table_unlock(hash, &flags); | |
1257 | } | |
1258 | free_rp_inst(rp); | |
1259 | } | |
1260 | NOKPROBE_SYMBOL(cleanup_rp_inst); | |
1261 | ||
1262 | /* | |
1263 | * Add the new probe to ap->list. Fail if this is the | |
1264 | * second jprobe at the address - two jprobes can't coexist | |
1265 | */ | |
1266 | static int add_new_kprobe(struct kprobe *ap, struct kprobe *p) | |
1267 | { | |
1268 | BUG_ON(kprobe_gone(ap) || kprobe_gone(p)); | |
1269 | ||
1270 | if (p->break_handler || p->post_handler) | |
1271 | unoptimize_kprobe(ap, true); /* Fall back to normal kprobe */ | |
1272 | ||
1273 | if (p->break_handler) { | |
1274 | if (ap->break_handler) | |
1275 | return -EEXIST; | |
1276 | list_add_tail_rcu(&p->list, &ap->list); | |
1277 | ap->break_handler = aggr_break_handler; | |
1278 | } else | |
1279 | list_add_rcu(&p->list, &ap->list); | |
1280 | if (p->post_handler && !ap->post_handler) | |
1281 | ap->post_handler = aggr_post_handler; | |
1282 | ||
1283 | return 0; | |
1284 | } | |
1285 | ||
1286 | /* | |
1287 | * Fill in the required fields of the "manager kprobe". Replace the | |
1288 | * earlier kprobe in the hlist with the manager kprobe | |
1289 | */ | |
1290 | static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p) | |
1291 | { | |
1292 | /* Copy p's insn slot to ap */ | |
1293 | copy_kprobe(p, ap); | |
1294 | flush_insn_slot(ap); | |
1295 | ap->addr = p->addr; | |
1296 | ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED; | |
1297 | ap->pre_handler = aggr_pre_handler; | |
1298 | ap->fault_handler = aggr_fault_handler; | |
1299 | /* We don't care the kprobe which has gone. */ | |
1300 | if (p->post_handler && !kprobe_gone(p)) | |
1301 | ap->post_handler = aggr_post_handler; | |
1302 | if (p->break_handler && !kprobe_gone(p)) | |
1303 | ap->break_handler = aggr_break_handler; | |
1304 | ||
1305 | INIT_LIST_HEAD(&ap->list); | |
1306 | INIT_HLIST_NODE(&ap->hlist); | |
1307 | ||
1308 | list_add_rcu(&p->list, &ap->list); | |
1309 | hlist_replace_rcu(&p->hlist, &ap->hlist); | |
1310 | } | |
1311 | ||
1312 | /* | |
1313 | * This is the second or subsequent kprobe at the address - handle | |
1314 | * the intricacies | |
1315 | */ | |
1316 | static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p) | |
1317 | { | |
1318 | int ret = 0; | |
1319 | struct kprobe *ap = orig_p; | |
1320 | ||
1321 | cpus_read_lock(); | |
1322 | ||
1323 | /* For preparing optimization, jump_label_text_reserved() is called */ | |
1324 | jump_label_lock(); | |
1325 | mutex_lock(&text_mutex); | |
1326 | ||
1327 | if (!kprobe_aggrprobe(orig_p)) { | |
1328 | /* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */ | |
1329 | ap = alloc_aggr_kprobe(orig_p); | |
1330 | if (!ap) { | |
1331 | ret = -ENOMEM; | |
1332 | goto out; | |
1333 | } | |
1334 | init_aggr_kprobe(ap, orig_p); | |
1335 | } else if (kprobe_unused(ap)) { | |
1336 | /* This probe is going to die. Rescue it */ | |
1337 | ret = reuse_unused_kprobe(ap); | |
1338 | if (ret) | |
1339 | goto out; | |
1340 | } | |
1341 | ||
1342 | if (kprobe_gone(ap)) { | |
1343 | /* | |
1344 | * Attempting to insert new probe at the same location that | |
1345 | * had a probe in the module vaddr area which already | |
1346 | * freed. So, the instruction slot has already been | |
1347 | * released. We need a new slot for the new probe. | |
1348 | */ | |
1349 | ret = arch_prepare_kprobe(ap); | |
1350 | if (ret) | |
1351 | /* | |
1352 | * Even if fail to allocate new slot, don't need to | |
1353 | * free aggr_probe. It will be used next time, or | |
1354 | * freed by unregister_kprobe. | |
1355 | */ | |
1356 | goto out; | |
1357 | ||
1358 | /* Prepare optimized instructions if possible. */ | |
1359 | prepare_optimized_kprobe(ap); | |
1360 | ||
1361 | /* | |
1362 | * Clear gone flag to prevent allocating new slot again, and | |
1363 | * set disabled flag because it is not armed yet. | |
1364 | */ | |
1365 | ap->flags = (ap->flags & ~KPROBE_FLAG_GONE) | |
1366 | | KPROBE_FLAG_DISABLED; | |
1367 | } | |
1368 | ||
1369 | /* Copy ap's insn slot to p */ | |
1370 | copy_kprobe(ap, p); | |
1371 | ret = add_new_kprobe(ap, p); | |
1372 | ||
1373 | out: | |
1374 | mutex_unlock(&text_mutex); | |
1375 | jump_label_unlock(); | |
1376 | cpus_read_unlock(); | |
1377 | ||
1378 | if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) { | |
1379 | ap->flags &= ~KPROBE_FLAG_DISABLED; | |
1380 | if (!kprobes_all_disarmed) | |
1381 | /* Arm the breakpoint again. */ | |
1382 | arm_kprobe(ap); | |
1383 | } | |
1384 | return ret; | |
1385 | } | |
1386 | ||
1387 | bool __weak arch_within_kprobe_blacklist(unsigned long addr) | |
1388 | { | |
1389 | /* The __kprobes marked functions and entry code must not be probed */ | |
1390 | return addr >= (unsigned long)__kprobes_text_start && | |
1391 | addr < (unsigned long)__kprobes_text_end; | |
1392 | } | |
1393 | ||
1394 | bool within_kprobe_blacklist(unsigned long addr) | |
1395 | { | |
1396 | struct kprobe_blacklist_entry *ent; | |
1397 | ||
1398 | if (arch_within_kprobe_blacklist(addr)) | |
1399 | return true; | |
1400 | /* | |
1401 | * If there exists a kprobe_blacklist, verify and | |
1402 | * fail any probe registration in the prohibited area | |
1403 | */ | |
1404 | list_for_each_entry(ent, &kprobe_blacklist, list) { | |
1405 | if (addr >= ent->start_addr && addr < ent->end_addr) | |
1406 | return true; | |
1407 | } | |
1408 | ||
1409 | return false; | |
1410 | } | |
1411 | ||
1412 | /* | |
1413 | * If we have a symbol_name argument, look it up and add the offset field | |
1414 | * to it. This way, we can specify a relative address to a symbol. | |
1415 | * This returns encoded errors if it fails to look up symbol or invalid | |
1416 | * combination of parameters. | |
1417 | */ | |
1418 | static kprobe_opcode_t *_kprobe_addr(kprobe_opcode_t *addr, | |
1419 | const char *symbol_name, unsigned int offset) | |
1420 | { | |
1421 | if ((symbol_name && addr) || (!symbol_name && !addr)) | |
1422 | goto invalid; | |
1423 | ||
1424 | if (symbol_name) { | |
1425 | addr = kprobe_lookup_name(symbol_name, offset); | |
1426 | if (!addr) | |
1427 | return ERR_PTR(-ENOENT); | |
1428 | } | |
1429 | ||
1430 | addr = (kprobe_opcode_t *)(((char *)addr) + offset); | |
1431 | if (addr) | |
1432 | return addr; | |
1433 | ||
1434 | invalid: | |
1435 | return ERR_PTR(-EINVAL); | |
1436 | } | |
1437 | ||
1438 | static kprobe_opcode_t *kprobe_addr(struct kprobe *p) | |
1439 | { | |
1440 | return _kprobe_addr(p->addr, p->symbol_name, p->offset); | |
1441 | } | |
1442 | ||
1443 | /* Check passed kprobe is valid and return kprobe in kprobe_table. */ | |
1444 | static struct kprobe *__get_valid_kprobe(struct kprobe *p) | |
1445 | { | |
1446 | struct kprobe *ap, *list_p; | |
1447 | ||
1448 | ap = get_kprobe(p->addr); | |
1449 | if (unlikely(!ap)) | |
1450 | return NULL; | |
1451 | ||
1452 | if (p != ap) { | |
1453 | list_for_each_entry_rcu(list_p, &ap->list, list) | |
1454 | if (list_p == p) | |
1455 | /* kprobe p is a valid probe */ | |
1456 | goto valid; | |
1457 | return NULL; | |
1458 | } | |
1459 | valid: | |
1460 | return ap; | |
1461 | } | |
1462 | ||
1463 | /* Return error if the kprobe is being re-registered */ | |
1464 | static inline int check_kprobe_rereg(struct kprobe *p) | |
1465 | { | |
1466 | int ret = 0; | |
1467 | ||
1468 | mutex_lock(&kprobe_mutex); | |
1469 | if (__get_valid_kprobe(p)) | |
1470 | ret = -EINVAL; | |
1471 | mutex_unlock(&kprobe_mutex); | |
1472 | ||
1473 | return ret; | |
1474 | } | |
1475 | ||
1476 | int __weak arch_check_ftrace_location(struct kprobe *p) | |
1477 | { | |
1478 | unsigned long ftrace_addr; | |
1479 | ||
1480 | ftrace_addr = ftrace_location((unsigned long)p->addr); | |
1481 | if (ftrace_addr) { | |
1482 | #ifdef CONFIG_KPROBES_ON_FTRACE | |
1483 | /* Given address is not on the instruction boundary */ | |
1484 | if ((unsigned long)p->addr != ftrace_addr) | |
1485 | return -EILSEQ; | |
1486 | p->flags |= KPROBE_FLAG_FTRACE; | |
1487 | #else /* !CONFIG_KPROBES_ON_FTRACE */ | |
1488 | return -EINVAL; | |
1489 | #endif | |
1490 | } | |
1491 | return 0; | |
1492 | } | |
1493 | ||
1494 | static int check_kprobe_address_safe(struct kprobe *p, | |
1495 | struct module **probed_mod) | |
1496 | { | |
1497 | int ret; | |
1498 | ||
1499 | ret = arch_check_ftrace_location(p); | |
1500 | if (ret) | |
1501 | return ret; | |
1502 | jump_label_lock(); | |
1503 | preempt_disable(); | |
1504 | ||
1505 | /* Ensure it is not in reserved area nor out of text */ | |
1506 | if (!kernel_text_address((unsigned long) p->addr) || | |
1507 | within_kprobe_blacklist((unsigned long) p->addr) || | |
1508 | jump_label_text_reserved(p->addr, p->addr) || | |
1509 | find_bug((unsigned long)p->addr)) { | |
1510 | ret = -EINVAL; | |
1511 | goto out; | |
1512 | } | |
1513 | ||
1514 | /* Check if are we probing a module */ | |
1515 | *probed_mod = __module_text_address((unsigned long) p->addr); | |
1516 | if (*probed_mod) { | |
1517 | /* | |
1518 | * We must hold a refcount of the probed module while updating | |
1519 | * its code to prohibit unexpected unloading. | |
1520 | */ | |
1521 | if (unlikely(!try_module_get(*probed_mod))) { | |
1522 | ret = -ENOENT; | |
1523 | goto out; | |
1524 | } | |
1525 | ||
1526 | /* | |
1527 | * If the module freed .init.text, we couldn't insert | |
1528 | * kprobes in there. | |
1529 | */ | |
1530 | if (within_module_init((unsigned long)p->addr, *probed_mod) && | |
1531 | (*probed_mod)->state != MODULE_STATE_COMING) { | |
1532 | module_put(*probed_mod); | |
1533 | *probed_mod = NULL; | |
1534 | ret = -ENOENT; | |
1535 | } | |
1536 | } | |
1537 | out: | |
1538 | preempt_enable(); | |
1539 | jump_label_unlock(); | |
1540 | ||
1541 | return ret; | |
1542 | } | |
1543 | ||
1544 | int register_kprobe(struct kprobe *p) | |
1545 | { | |
1546 | int ret; | |
1547 | struct kprobe *old_p; | |
1548 | struct module *probed_mod; | |
1549 | kprobe_opcode_t *addr; | |
1550 | ||
1551 | /* Adjust probe address from symbol */ | |
1552 | addr = kprobe_addr(p); | |
1553 | if (IS_ERR(addr)) | |
1554 | return PTR_ERR(addr); | |
1555 | p->addr = addr; | |
1556 | ||
1557 | ret = check_kprobe_rereg(p); | |
1558 | if (ret) | |
1559 | return ret; | |
1560 | ||
1561 | /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */ | |
1562 | p->flags &= KPROBE_FLAG_DISABLED; | |
1563 | p->nmissed = 0; | |
1564 | INIT_LIST_HEAD(&p->list); | |
1565 | ||
1566 | ret = check_kprobe_address_safe(p, &probed_mod); | |
1567 | if (ret) | |
1568 | return ret; | |
1569 | ||
1570 | mutex_lock(&kprobe_mutex); | |
1571 | ||
1572 | old_p = get_kprobe(p->addr); | |
1573 | if (old_p) { | |
1574 | /* Since this may unoptimize old_p, locking text_mutex. */ | |
1575 | ret = register_aggr_kprobe(old_p, p); | |
1576 | goto out; | |
1577 | } | |
1578 | ||
1579 | cpus_read_lock(); | |
1580 | /* Prevent text modification */ | |
1581 | mutex_lock(&text_mutex); | |
1582 | ret = prepare_kprobe(p); | |
1583 | mutex_unlock(&text_mutex); | |
1584 | cpus_read_unlock(); | |
1585 | if (ret) | |
1586 | goto out; | |
1587 | ||
1588 | INIT_HLIST_NODE(&p->hlist); | |
1589 | hlist_add_head_rcu(&p->hlist, | |
1590 | &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]); | |
1591 | ||
1592 | if (!kprobes_all_disarmed && !kprobe_disabled(p)) | |
1593 | arm_kprobe(p); | |
1594 | ||
1595 | /* Try to optimize kprobe */ | |
1596 | try_to_optimize_kprobe(p); | |
1597 | out: | |
1598 | mutex_unlock(&kprobe_mutex); | |
1599 | ||
1600 | if (probed_mod) | |
1601 | module_put(probed_mod); | |
1602 | ||
1603 | return ret; | |
1604 | } | |
1605 | EXPORT_SYMBOL_GPL(register_kprobe); | |
1606 | ||
1607 | /* Check if all probes on the aggrprobe are disabled */ | |
1608 | static int aggr_kprobe_disabled(struct kprobe *ap) | |
1609 | { | |
1610 | struct kprobe *kp; | |
1611 | ||
1612 | list_for_each_entry_rcu(kp, &ap->list, list) | |
1613 | if (!kprobe_disabled(kp)) | |
1614 | /* | |
1615 | * There is an active probe on the list. | |
1616 | * We can't disable this ap. | |
1617 | */ | |
1618 | return 0; | |
1619 | ||
1620 | return 1; | |
1621 | } | |
1622 | ||
1623 | /* Disable one kprobe: Make sure called under kprobe_mutex is locked */ | |
1624 | static struct kprobe *__disable_kprobe(struct kprobe *p) | |
1625 | { | |
1626 | struct kprobe *orig_p; | |
1627 | ||
1628 | /* Get an original kprobe for return */ | |
1629 | orig_p = __get_valid_kprobe(p); | |
1630 | if (unlikely(orig_p == NULL)) | |
1631 | return NULL; | |
1632 | ||
1633 | if (!kprobe_disabled(p)) { | |
1634 | /* Disable probe if it is a child probe */ | |
1635 | if (p != orig_p) | |
1636 | p->flags |= KPROBE_FLAG_DISABLED; | |
1637 | ||
1638 | /* Try to disarm and disable this/parent probe */ | |
1639 | if (p == orig_p || aggr_kprobe_disabled(orig_p)) { | |
1640 | /* | |
1641 | * If kprobes_all_disarmed is set, orig_p | |
1642 | * should have already been disarmed, so | |
1643 | * skip unneed disarming process. | |
1644 | */ | |
1645 | if (!kprobes_all_disarmed) | |
1646 | disarm_kprobe(orig_p, true); | |
1647 | orig_p->flags |= KPROBE_FLAG_DISABLED; | |
1648 | } | |
1649 | } | |
1650 | ||
1651 | return orig_p; | |
1652 | } | |
1653 | ||
1654 | /* | |
1655 | * Unregister a kprobe without a scheduler synchronization. | |
1656 | */ | |
1657 | static int __unregister_kprobe_top(struct kprobe *p) | |
1658 | { | |
1659 | struct kprobe *ap, *list_p; | |
1660 | ||
1661 | /* Disable kprobe. This will disarm it if needed. */ | |
1662 | ap = __disable_kprobe(p); | |
1663 | if (ap == NULL) | |
1664 | return -EINVAL; | |
1665 | ||
1666 | if (ap == p) | |
1667 | /* | |
1668 | * This probe is an independent(and non-optimized) kprobe | |
1669 | * (not an aggrprobe). Remove from the hash list. | |
1670 | */ | |
1671 | goto disarmed; | |
1672 | ||
1673 | /* Following process expects this probe is an aggrprobe */ | |
1674 | WARN_ON(!kprobe_aggrprobe(ap)); | |
1675 | ||
1676 | if (list_is_singular(&ap->list) && kprobe_disarmed(ap)) | |
1677 | /* | |
1678 | * !disarmed could be happen if the probe is under delayed | |
1679 | * unoptimizing. | |
1680 | */ | |
1681 | goto disarmed; | |
1682 | else { | |
1683 | /* If disabling probe has special handlers, update aggrprobe */ | |
1684 | if (p->break_handler && !kprobe_gone(p)) | |
1685 | ap->break_handler = NULL; | |
1686 | if (p->post_handler && !kprobe_gone(p)) { | |
1687 | list_for_each_entry_rcu(list_p, &ap->list, list) { | |
1688 | if ((list_p != p) && (list_p->post_handler)) | |
1689 | goto noclean; | |
1690 | } | |
1691 | ap->post_handler = NULL; | |
1692 | } | |
1693 | noclean: | |
1694 | /* | |
1695 | * Remove from the aggrprobe: this path will do nothing in | |
1696 | * __unregister_kprobe_bottom(). | |
1697 | */ | |
1698 | list_del_rcu(&p->list); | |
1699 | if (!kprobe_disabled(ap) && !kprobes_all_disarmed) | |
1700 | /* | |
1701 | * Try to optimize this probe again, because post | |
1702 | * handler may have been changed. | |
1703 | */ | |
1704 | optimize_kprobe(ap); | |
1705 | } | |
1706 | return 0; | |
1707 | ||
1708 | disarmed: | |
1709 | BUG_ON(!kprobe_disarmed(ap)); | |
1710 | hlist_del_rcu(&ap->hlist); | |
1711 | return 0; | |
1712 | } | |
1713 | ||
1714 | static void __unregister_kprobe_bottom(struct kprobe *p) | |
1715 | { | |
1716 | struct kprobe *ap; | |
1717 | ||
1718 | if (list_empty(&p->list)) | |
1719 | /* This is an independent kprobe */ | |
1720 | arch_remove_kprobe(p); | |
1721 | else if (list_is_singular(&p->list)) { | |
1722 | /* This is the last child of an aggrprobe */ | |
1723 | ap = list_entry(p->list.next, struct kprobe, list); | |
1724 | list_del(&p->list); | |
1725 | free_aggr_kprobe(ap); | |
1726 | } | |
1727 | /* Otherwise, do nothing. */ | |
1728 | } | |
1729 | ||
1730 | int register_kprobes(struct kprobe **kps, int num) | |
1731 | { | |
1732 | int i, ret = 0; | |
1733 | ||
1734 | if (num <= 0) | |
1735 | return -EINVAL; | |
1736 | for (i = 0; i < num; i++) { | |
1737 | ret = register_kprobe(kps[i]); | |
1738 | if (ret < 0) { | |
1739 | if (i > 0) | |
1740 | unregister_kprobes(kps, i); | |
1741 | break; | |
1742 | } | |
1743 | } | |
1744 | return ret; | |
1745 | } | |
1746 | EXPORT_SYMBOL_GPL(register_kprobes); | |
1747 | ||
1748 | void unregister_kprobe(struct kprobe *p) | |
1749 | { | |
1750 | unregister_kprobes(&p, 1); | |
1751 | } | |
1752 | EXPORT_SYMBOL_GPL(unregister_kprobe); | |
1753 | ||
1754 | void unregister_kprobes(struct kprobe **kps, int num) | |
1755 | { | |
1756 | int i; | |
1757 | ||
1758 | if (num <= 0) | |
1759 | return; | |
1760 | mutex_lock(&kprobe_mutex); | |
1761 | for (i = 0; i < num; i++) | |
1762 | if (__unregister_kprobe_top(kps[i]) < 0) | |
1763 | kps[i]->addr = NULL; | |
1764 | mutex_unlock(&kprobe_mutex); | |
1765 | ||
1766 | synchronize_sched(); | |
1767 | for (i = 0; i < num; i++) | |
1768 | if (kps[i]->addr) | |
1769 | __unregister_kprobe_bottom(kps[i]); | |
1770 | } | |
1771 | EXPORT_SYMBOL_GPL(unregister_kprobes); | |
1772 | ||
1773 | int __weak kprobe_exceptions_notify(struct notifier_block *self, | |
1774 | unsigned long val, void *data) | |
1775 | { | |
1776 | return NOTIFY_DONE; | |
1777 | } | |
1778 | NOKPROBE_SYMBOL(kprobe_exceptions_notify); | |
1779 | ||
1780 | static struct notifier_block kprobe_exceptions_nb = { | |
1781 | .notifier_call = kprobe_exceptions_notify, | |
1782 | .priority = 0x7fffffff /* we need to be notified first */ | |
1783 | }; | |
1784 | ||
1785 | unsigned long __weak arch_deref_entry_point(void *entry) | |
1786 | { | |
1787 | return (unsigned long)entry; | |
1788 | } | |
1789 | ||
1790 | #if 0 | |
1791 | int register_jprobes(struct jprobe **jps, int num) | |
1792 | { | |
1793 | int ret = 0, i; | |
1794 | ||
1795 | if (num <= 0) | |
1796 | return -EINVAL; | |
1797 | ||
1798 | for (i = 0; i < num; i++) { | |
1799 | ret = register_jprobe(jps[i]); | |
1800 | ||
1801 | if (ret < 0) { | |
1802 | if (i > 0) | |
1803 | unregister_jprobes(jps, i); | |
1804 | break; | |
1805 | } | |
1806 | } | |
1807 | ||
1808 | return ret; | |
1809 | } | |
1810 | EXPORT_SYMBOL_GPL(register_jprobes); | |
1811 | ||
1812 | int register_jprobe(struct jprobe *jp) | |
1813 | { | |
1814 | unsigned long addr, offset; | |
1815 | struct kprobe *kp = &jp->kp; | |
1816 | ||
1817 | /* | |
1818 | * Verify probepoint as well as the jprobe handler are | |
1819 | * valid function entry points. | |
1820 | */ | |
1821 | addr = arch_deref_entry_point(jp->entry); | |
1822 | ||
1823 | if (kallsyms_lookup_size_offset(addr, NULL, &offset) && offset == 0 && | |
1824 | kprobe_on_func_entry(kp->addr, kp->symbol_name, kp->offset)) { | |
1825 | kp->pre_handler = setjmp_pre_handler; | |
1826 | kp->break_handler = longjmp_break_handler; | |
1827 | return register_kprobe(kp); | |
1828 | } | |
1829 | ||
1830 | return -EINVAL; | |
1831 | } | |
1832 | EXPORT_SYMBOL_GPL(register_jprobe); | |
1833 | ||
1834 | void unregister_jprobe(struct jprobe *jp) | |
1835 | { | |
1836 | unregister_jprobes(&jp, 1); | |
1837 | } | |
1838 | EXPORT_SYMBOL_GPL(unregister_jprobe); | |
1839 | ||
1840 | void unregister_jprobes(struct jprobe **jps, int num) | |
1841 | { | |
1842 | int i; | |
1843 | ||
1844 | if (num <= 0) | |
1845 | return; | |
1846 | mutex_lock(&kprobe_mutex); | |
1847 | for (i = 0; i < num; i++) | |
1848 | if (__unregister_kprobe_top(&jps[i]->kp) < 0) | |
1849 | jps[i]->kp.addr = NULL; | |
1850 | mutex_unlock(&kprobe_mutex); | |
1851 | ||
1852 | synchronize_sched(); | |
1853 | for (i = 0; i < num; i++) { | |
1854 | if (jps[i]->kp.addr) | |
1855 | __unregister_kprobe_bottom(&jps[i]->kp); | |
1856 | } | |
1857 | } | |
1858 | EXPORT_SYMBOL_GPL(unregister_jprobes); | |
1859 | #endif | |
1860 | ||
1861 | #ifdef CONFIG_KRETPROBES | |
1862 | /* | |
1863 | * This kprobe pre_handler is registered with every kretprobe. When probe | |
1864 | * hits it will set up the return probe. | |
1865 | */ | |
1866 | static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs) | |
1867 | { | |
1868 | struct kretprobe *rp = container_of(p, struct kretprobe, kp); | |
1869 | unsigned long hash, flags = 0; | |
1870 | struct kretprobe_instance *ri; | |
1871 | ||
1872 | /* | |
1873 | * To avoid deadlocks, prohibit return probing in NMI contexts, | |
1874 | * just skip the probe and increase the (inexact) 'nmissed' | |
1875 | * statistical counter, so that the user is informed that | |
1876 | * something happened: | |
1877 | */ | |
1878 | if (unlikely(in_nmi())) { | |
1879 | rp->nmissed++; | |
1880 | return 0; | |
1881 | } | |
1882 | ||
1883 | /* TODO: consider to only swap the RA after the last pre_handler fired */ | |
1884 | hash = hash_ptr(current, KPROBE_HASH_BITS); | |
1885 | raw_spin_lock_irqsave(&rp->lock, flags); | |
1886 | if (!hlist_empty(&rp->free_instances)) { | |
1887 | ri = hlist_entry(rp->free_instances.first, | |
1888 | struct kretprobe_instance, hlist); | |
1889 | hlist_del(&ri->hlist); | |
1890 | raw_spin_unlock_irqrestore(&rp->lock, flags); | |
1891 | ||
1892 | ri->rp = rp; | |
1893 | ri->task = current; | |
1894 | ||
1895 | if (rp->entry_handler && rp->entry_handler(ri, regs)) { | |
1896 | raw_spin_lock_irqsave(&rp->lock, flags); | |
1897 | hlist_add_head(&ri->hlist, &rp->free_instances); | |
1898 | raw_spin_unlock_irqrestore(&rp->lock, flags); | |
1899 | return 0; | |
1900 | } | |
1901 | ||
1902 | arch_prepare_kretprobe(ri, regs); | |
1903 | ||
1904 | /* XXX(hch): why is there no hlist_move_head? */ | |
1905 | INIT_HLIST_NODE(&ri->hlist); | |
1906 | kretprobe_table_lock(hash, &flags); | |
1907 | hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]); | |
1908 | kretprobe_table_unlock(hash, &flags); | |
1909 | } else { | |
1910 | rp->nmissed++; | |
1911 | raw_spin_unlock_irqrestore(&rp->lock, flags); | |
1912 | } | |
1913 | return 0; | |
1914 | } | |
1915 | NOKPROBE_SYMBOL(pre_handler_kretprobe); | |
1916 | ||
1917 | bool __weak arch_kprobe_on_func_entry(unsigned long offset) | |
1918 | { | |
1919 | return !offset; | |
1920 | } | |
1921 | ||
1922 | bool kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset) | |
1923 | { | |
1924 | kprobe_opcode_t *kp_addr = _kprobe_addr(addr, sym, offset); | |
1925 | ||
1926 | if (IS_ERR(kp_addr)) | |
1927 | return false; | |
1928 | ||
1929 | if (!kallsyms_lookup_size_offset((unsigned long)kp_addr, NULL, &offset) || | |
1930 | !arch_kprobe_on_func_entry(offset)) | |
1931 | return false; | |
1932 | ||
1933 | return true; | |
1934 | } | |
1935 | ||
1936 | int register_kretprobe(struct kretprobe *rp) | |
1937 | { | |
1938 | int ret = 0; | |
1939 | struct kretprobe_instance *inst; | |
1940 | int i; | |
1941 | void *addr; | |
1942 | ||
1943 | if (!kprobe_on_func_entry(rp->kp.addr, rp->kp.symbol_name, rp->kp.offset)) | |
1944 | return -EINVAL; | |
1945 | ||
1946 | if (kretprobe_blacklist_size) { | |
1947 | addr = kprobe_addr(&rp->kp); | |
1948 | if (IS_ERR(addr)) | |
1949 | return PTR_ERR(addr); | |
1950 | ||
1951 | for (i = 0; kretprobe_blacklist[i].name != NULL; i++) { | |
1952 | if (kretprobe_blacklist[i].addr == addr) | |
1953 | return -EINVAL; | |
1954 | } | |
1955 | } | |
1956 | ||
1957 | rp->kp.pre_handler = pre_handler_kretprobe; | |
1958 | rp->kp.post_handler = NULL; | |
1959 | rp->kp.fault_handler = NULL; | |
1960 | rp->kp.break_handler = NULL; | |
1961 | ||
1962 | /* Pre-allocate memory for max kretprobe instances */ | |
1963 | if (rp->maxactive <= 0) { | |
1964 | #ifdef CONFIG_PREEMPT | |
1965 | rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus()); | |
1966 | #else | |
1967 | rp->maxactive = num_possible_cpus(); | |
1968 | #endif | |
1969 | } | |
1970 | raw_spin_lock_init(&rp->lock); | |
1971 | INIT_HLIST_HEAD(&rp->free_instances); | |
1972 | for (i = 0; i < rp->maxactive; i++) { | |
1973 | inst = kmalloc(sizeof(struct kretprobe_instance) + | |
1974 | rp->data_size, GFP_KERNEL); | |
1975 | if (inst == NULL) { | |
1976 | free_rp_inst(rp); | |
1977 | return -ENOMEM; | |
1978 | } | |
1979 | INIT_HLIST_NODE(&inst->hlist); | |
1980 | hlist_add_head(&inst->hlist, &rp->free_instances); | |
1981 | } | |
1982 | ||
1983 | rp->nmissed = 0; | |
1984 | /* Establish function entry probe point */ | |
1985 | ret = register_kprobe(&rp->kp); | |
1986 | if (ret != 0) | |
1987 | free_rp_inst(rp); | |
1988 | return ret; | |
1989 | } | |
1990 | EXPORT_SYMBOL_GPL(register_kretprobe); | |
1991 | ||
1992 | int register_kretprobes(struct kretprobe **rps, int num) | |
1993 | { | |
1994 | int ret = 0, i; | |
1995 | ||
1996 | if (num <= 0) | |
1997 | return -EINVAL; | |
1998 | for (i = 0; i < num; i++) { | |
1999 | ret = register_kretprobe(rps[i]); | |
2000 | if (ret < 0) { | |
2001 | if (i > 0) | |
2002 | unregister_kretprobes(rps, i); | |
2003 | break; | |
2004 | } | |
2005 | } | |
2006 | return ret; | |
2007 | } | |
2008 | EXPORT_SYMBOL_GPL(register_kretprobes); | |
2009 | ||
2010 | void unregister_kretprobe(struct kretprobe *rp) | |
2011 | { | |
2012 | unregister_kretprobes(&rp, 1); | |
2013 | } | |
2014 | EXPORT_SYMBOL_GPL(unregister_kretprobe); | |
2015 | ||
2016 | void unregister_kretprobes(struct kretprobe **rps, int num) | |
2017 | { | |
2018 | int i; | |
2019 | ||
2020 | if (num <= 0) | |
2021 | return; | |
2022 | mutex_lock(&kprobe_mutex); | |
2023 | for (i = 0; i < num; i++) | |
2024 | if (__unregister_kprobe_top(&rps[i]->kp) < 0) | |
2025 | rps[i]->kp.addr = NULL; | |
2026 | mutex_unlock(&kprobe_mutex); | |
2027 | ||
2028 | synchronize_sched(); | |
2029 | for (i = 0; i < num; i++) { | |
2030 | if (rps[i]->kp.addr) { | |
2031 | __unregister_kprobe_bottom(&rps[i]->kp); | |
2032 | cleanup_rp_inst(rps[i]); | |
2033 | } | |
2034 | } | |
2035 | } | |
2036 | EXPORT_SYMBOL_GPL(unregister_kretprobes); | |
2037 | ||
2038 | #else /* CONFIG_KRETPROBES */ | |
2039 | int register_kretprobe(struct kretprobe *rp) | |
2040 | { | |
2041 | return -ENOSYS; | |
2042 | } | |
2043 | EXPORT_SYMBOL_GPL(register_kretprobe); | |
2044 | ||
2045 | int register_kretprobes(struct kretprobe **rps, int num) | |
2046 | { | |
2047 | return -ENOSYS; | |
2048 | } | |
2049 | EXPORT_SYMBOL_GPL(register_kretprobes); | |
2050 | ||
2051 | void unregister_kretprobe(struct kretprobe *rp) | |
2052 | { | |
2053 | } | |
2054 | EXPORT_SYMBOL_GPL(unregister_kretprobe); | |
2055 | ||
2056 | void unregister_kretprobes(struct kretprobe **rps, int num) | |
2057 | { | |
2058 | } | |
2059 | EXPORT_SYMBOL_GPL(unregister_kretprobes); | |
2060 | ||
2061 | static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs) | |
2062 | { | |
2063 | return 0; | |
2064 | } | |
2065 | NOKPROBE_SYMBOL(pre_handler_kretprobe); | |
2066 | ||
2067 | #endif /* CONFIG_KRETPROBES */ | |
2068 | ||
2069 | /* Set the kprobe gone and remove its instruction buffer. */ | |
2070 | static void kill_kprobe(struct kprobe *p) | |
2071 | { | |
2072 | struct kprobe *kp; | |
2073 | ||
2074 | p->flags |= KPROBE_FLAG_GONE; | |
2075 | if (kprobe_aggrprobe(p)) { | |
2076 | /* | |
2077 | * If this is an aggr_kprobe, we have to list all the | |
2078 | * chained probes and mark them GONE. | |
2079 | */ | |
2080 | list_for_each_entry_rcu(kp, &p->list, list) | |
2081 | kp->flags |= KPROBE_FLAG_GONE; | |
2082 | p->post_handler = NULL; | |
2083 | p->break_handler = NULL; | |
2084 | kill_optimized_kprobe(p); | |
2085 | } | |
2086 | /* | |
2087 | * Here, we can remove insn_slot safely, because no thread calls | |
2088 | * the original probed function (which will be freed soon) any more. | |
2089 | */ | |
2090 | arch_remove_kprobe(p); | |
2091 | } | |
2092 | ||
2093 | /* Disable one kprobe */ | |
2094 | int disable_kprobe(struct kprobe *kp) | |
2095 | { | |
2096 | int ret = 0; | |
2097 | ||
2098 | mutex_lock(&kprobe_mutex); | |
2099 | ||
2100 | /* Disable this kprobe */ | |
2101 | if (__disable_kprobe(kp) == NULL) | |
2102 | ret = -EINVAL; | |
2103 | ||
2104 | mutex_unlock(&kprobe_mutex); | |
2105 | return ret; | |
2106 | } | |
2107 | EXPORT_SYMBOL_GPL(disable_kprobe); | |
2108 | ||
2109 | /* Enable one kprobe */ | |
2110 | int enable_kprobe(struct kprobe *kp) | |
2111 | { | |
2112 | int ret = 0; | |
2113 | struct kprobe *p; | |
2114 | ||
2115 | mutex_lock(&kprobe_mutex); | |
2116 | ||
2117 | /* Check whether specified probe is valid. */ | |
2118 | p = __get_valid_kprobe(kp); | |
2119 | if (unlikely(p == NULL)) { | |
2120 | ret = -EINVAL; | |
2121 | goto out; | |
2122 | } | |
2123 | ||
2124 | if (kprobe_gone(kp)) { | |
2125 | /* This kprobe has gone, we couldn't enable it. */ | |
2126 | ret = -EINVAL; | |
2127 | goto out; | |
2128 | } | |
2129 | ||
2130 | if (p != kp) | |
2131 | kp->flags &= ~KPROBE_FLAG_DISABLED; | |
2132 | ||
2133 | if (!kprobes_all_disarmed && kprobe_disabled(p)) { | |
2134 | p->flags &= ~KPROBE_FLAG_DISABLED; | |
2135 | arm_kprobe(p); | |
2136 | } | |
2137 | out: | |
2138 | mutex_unlock(&kprobe_mutex); | |
2139 | return ret; | |
2140 | } | |
2141 | EXPORT_SYMBOL_GPL(enable_kprobe); | |
2142 | ||
2143 | /* Caller must NOT call this in usual path. This is only for critical case */ | |
2144 | void dump_kprobe(struct kprobe *kp) | |
2145 | { | |
2146 | pr_err("Dumping kprobe:\n"); | |
2147 | pr_err("Name: %s\nOffset: %x\nAddress: %pS\n", | |
2148 | kp->symbol_name, kp->offset, kp->addr); | |
2149 | } | |
2150 | NOKPROBE_SYMBOL(dump_kprobe); | |
2151 | ||
2152 | int kprobe_add_ksym_blacklist(unsigned long entry) | |
2153 | { | |
2154 | struct kprobe_blacklist_entry *ent; | |
2155 | unsigned long offset = 0, size = 0; | |
2156 | ||
2157 | if (!kernel_text_address(entry) || | |
2158 | !kallsyms_lookup_size_offset(entry, &size, &offset)) | |
2159 | return -EINVAL; | |
2160 | ||
2161 | ent = kmalloc(sizeof(*ent), GFP_KERNEL); | |
2162 | if (!ent) | |
2163 | return -ENOMEM; | |
2164 | ent->start_addr = entry; | |
2165 | ent->end_addr = entry + size; | |
2166 | INIT_LIST_HEAD(&ent->list); | |
2167 | list_add_tail(&ent->list, &kprobe_blacklist); | |
2168 | ||
2169 | return (int)size; | |
2170 | } | |
2171 | ||
2172 | /* Add all symbols in given area into kprobe blacklist */ | |
2173 | int kprobe_add_area_blacklist(unsigned long start, unsigned long end) | |
2174 | { | |
2175 | unsigned long entry; | |
2176 | int ret = 0; | |
2177 | ||
2178 | for (entry = start; entry < end; entry += ret) { | |
2179 | ret = kprobe_add_ksym_blacklist(entry); | |
2180 | if (ret < 0) | |
2181 | return ret; | |
2182 | if (ret == 0) /* In case of alias symbol */ | |
2183 | ret = 1; | |
2184 | } | |
2185 | return 0; | |
2186 | } | |
2187 | ||
2188 | int __init __weak arch_populate_kprobe_blacklist(void) | |
2189 | { | |
2190 | return 0; | |
2191 | } | |
2192 | ||
2193 | /* | |
2194 | * Lookup and populate the kprobe_blacklist. | |
2195 | * | |
2196 | * Unlike the kretprobe blacklist, we'll need to determine | |
2197 | * the range of addresses that belong to the said functions, | |
2198 | * since a kprobe need not necessarily be at the beginning | |
2199 | * of a function. | |
2200 | */ | |
2201 | static int __init populate_kprobe_blacklist(unsigned long *start, | |
2202 | unsigned long *end) | |
2203 | { | |
2204 | unsigned long entry; | |
2205 | unsigned long *iter; | |
2206 | int ret; | |
2207 | ||
2208 | for (iter = start; iter < end; iter++) { | |
2209 | entry = arch_deref_entry_point((void *)*iter); | |
2210 | ret = kprobe_add_ksym_blacklist(entry); | |
2211 | if (ret == -EINVAL) | |
2212 | continue; | |
2213 | if (ret < 0) | |
2214 | return ret; | |
2215 | } | |
2216 | ||
2217 | /* Symbols in __kprobes_text are blacklisted */ | |
2218 | ret = kprobe_add_area_blacklist((unsigned long)__kprobes_text_start, | |
2219 | (unsigned long)__kprobes_text_end); | |
2220 | ||
2221 | return ret ? : arch_populate_kprobe_blacklist(); | |
2222 | } | |
2223 | ||
2224 | /* Module notifier call back, checking kprobes on the module */ | |
2225 | static int kprobes_module_callback(struct notifier_block *nb, | |
2226 | unsigned long val, void *data) | |
2227 | { | |
2228 | struct module *mod = data; | |
2229 | struct hlist_head *head; | |
2230 | struct kprobe *p; | |
2231 | unsigned int i; | |
2232 | int checkcore = (val == MODULE_STATE_GOING); | |
2233 | ||
2234 | if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE) | |
2235 | return NOTIFY_DONE; | |
2236 | ||
2237 | /* | |
2238 | * When MODULE_STATE_GOING was notified, both of module .text and | |
2239 | * .init.text sections would be freed. When MODULE_STATE_LIVE was | |
2240 | * notified, only .init.text section would be freed. We need to | |
2241 | * disable kprobes which have been inserted in the sections. | |
2242 | */ | |
2243 | mutex_lock(&kprobe_mutex); | |
2244 | for (i = 0; i < KPROBE_TABLE_SIZE; i++) { | |
2245 | head = &kprobe_table[i]; | |
2246 | hlist_for_each_entry_rcu(p, head, hlist) | |
2247 | if (within_module_init((unsigned long)p->addr, mod) || | |
2248 | (checkcore && | |
2249 | within_module_core((unsigned long)p->addr, mod))) { | |
2250 | /* | |
2251 | * The vaddr this probe is installed will soon | |
2252 | * be vfreed buy not synced to disk. Hence, | |
2253 | * disarming the breakpoint isn't needed. | |
2254 | * | |
2255 | * Note, this will also move any optimized probes | |
2256 | * that are pending to be removed from their | |
2257 | * corresponding lists to the freeing_list and | |
2258 | * will not be touched by the delayed | |
2259 | * kprobe_optimizer work handler. | |
2260 | */ | |
2261 | kill_kprobe(p); | |
2262 | } | |
2263 | } | |
2264 | mutex_unlock(&kprobe_mutex); | |
2265 | return NOTIFY_DONE; | |
2266 | } | |
2267 | ||
2268 | static struct notifier_block kprobe_module_nb = { | |
2269 | .notifier_call = kprobes_module_callback, | |
2270 | .priority = 0 | |
2271 | }; | |
2272 | ||
2273 | /* Markers of _kprobe_blacklist section */ | |
2274 | extern unsigned long __start_kprobe_blacklist[]; | |
2275 | extern unsigned long __stop_kprobe_blacklist[]; | |
2276 | ||
2277 | static int __init init_kprobes(void) | |
2278 | { | |
2279 | int i, err = 0; | |
2280 | ||
2281 | /* FIXME allocate the probe table, currently defined statically */ | |
2282 | /* initialize all list heads */ | |
2283 | for (i = 0; i < KPROBE_TABLE_SIZE; i++) { | |
2284 | INIT_HLIST_HEAD(&kprobe_table[i]); | |
2285 | INIT_HLIST_HEAD(&kretprobe_inst_table[i]); | |
2286 | raw_spin_lock_init(&(kretprobe_table_locks[i].lock)); | |
2287 | } | |
2288 | ||
2289 | err = populate_kprobe_blacklist(__start_kprobe_blacklist, | |
2290 | __stop_kprobe_blacklist); | |
2291 | if (err) { | |
2292 | pr_err("kprobes: failed to populate blacklist: %d\n", err); | |
2293 | pr_err("Please take care of using kprobes.\n"); | |
2294 | } | |
2295 | ||
2296 | if (kretprobe_blacklist_size) { | |
2297 | /* lookup the function address from its name */ | |
2298 | for (i = 0; kretprobe_blacklist[i].name != NULL; i++) { | |
2299 | kretprobe_blacklist[i].addr = | |
2300 | kprobe_lookup_name(kretprobe_blacklist[i].name, 0); | |
2301 | if (!kretprobe_blacklist[i].addr) | |
2302 | printk("kretprobe: lookup failed: %s\n", | |
2303 | kretprobe_blacklist[i].name); | |
2304 | } | |
2305 | } | |
2306 | ||
2307 | #if defined(CONFIG_OPTPROBES) | |
2308 | #if defined(__ARCH_WANT_KPROBES_INSN_SLOT) | |
2309 | /* Init kprobe_optinsn_slots */ | |
2310 | kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE; | |
2311 | #endif | |
2312 | /* By default, kprobes can be optimized */ | |
2313 | kprobes_allow_optimization = true; | |
2314 | #endif | |
2315 | ||
2316 | /* By default, kprobes are armed */ | |
2317 | kprobes_all_disarmed = false; | |
2318 | ||
2319 | err = arch_init_kprobes(); | |
2320 | if (!err) | |
2321 | err = register_die_notifier(&kprobe_exceptions_nb); | |
2322 | if (!err) | |
2323 | err = register_module_notifier(&kprobe_module_nb); | |
2324 | ||
2325 | kprobes_initialized = (err == 0); | |
2326 | ||
2327 | if (!err) | |
2328 | init_test_probes(); | |
2329 | return err; | |
2330 | } | |
2331 | ||
2332 | #ifdef CONFIG_DEBUG_FS | |
2333 | static void report_probe(struct seq_file *pi, struct kprobe *p, | |
2334 | const char *sym, int offset, char *modname, struct kprobe *pp) | |
2335 | { | |
2336 | char *kprobe_type; | |
2337 | ||
2338 | if (p->pre_handler == pre_handler_kretprobe) | |
2339 | kprobe_type = "r"; | |
2340 | else if (p->pre_handler == setjmp_pre_handler) | |
2341 | kprobe_type = "j"; | |
2342 | else | |
2343 | kprobe_type = "k"; | |
2344 | ||
2345 | if (sym) | |
2346 | seq_printf(pi, "%p %s %s+0x%x %s ", | |
2347 | p->addr, kprobe_type, sym, offset, | |
2348 | (modname ? modname : " ")); | |
2349 | else | |
2350 | seq_printf(pi, "%p %s %p ", | |
2351 | p->addr, kprobe_type, p->addr); | |
2352 | ||
2353 | if (!pp) | |
2354 | pp = p; | |
2355 | seq_printf(pi, "%s%s%s%s\n", | |
2356 | (kprobe_gone(p) ? "[GONE]" : ""), | |
2357 | ((kprobe_disabled(p) && !kprobe_gone(p)) ? "[DISABLED]" : ""), | |
2358 | (kprobe_optimized(pp) ? "[OPTIMIZED]" : ""), | |
2359 | (kprobe_ftrace(pp) ? "[FTRACE]" : "")); | |
2360 | } | |
2361 | ||
2362 | static void *kprobe_seq_start(struct seq_file *f, loff_t *pos) | |
2363 | { | |
2364 | return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL; | |
2365 | } | |
2366 | ||
2367 | static void *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos) | |
2368 | { | |
2369 | (*pos)++; | |
2370 | if (*pos >= KPROBE_TABLE_SIZE) | |
2371 | return NULL; | |
2372 | return pos; | |
2373 | } | |
2374 | ||
2375 | static void kprobe_seq_stop(struct seq_file *f, void *v) | |
2376 | { | |
2377 | /* Nothing to do */ | |
2378 | } | |
2379 | ||
2380 | static int show_kprobe_addr(struct seq_file *pi, void *v) | |
2381 | { | |
2382 | struct hlist_head *head; | |
2383 | struct kprobe *p, *kp; | |
2384 | const char *sym = NULL; | |
2385 | unsigned int i = *(loff_t *) v; | |
2386 | unsigned long offset = 0; | |
2387 | char *modname, namebuf[KSYM_NAME_LEN]; | |
2388 | ||
2389 | head = &kprobe_table[i]; | |
2390 | preempt_disable(); | |
2391 | hlist_for_each_entry_rcu(p, head, hlist) { | |
2392 | sym = kallsyms_lookup((unsigned long)p->addr, NULL, | |
2393 | &offset, &modname, namebuf); | |
2394 | if (kprobe_aggrprobe(p)) { | |
2395 | list_for_each_entry_rcu(kp, &p->list, list) | |
2396 | report_probe(pi, kp, sym, offset, modname, p); | |
2397 | } else | |
2398 | report_probe(pi, p, sym, offset, modname, NULL); | |
2399 | } | |
2400 | preempt_enable(); | |
2401 | return 0; | |
2402 | } | |
2403 | ||
2404 | static const struct seq_operations kprobes_seq_ops = { | |
2405 | .start = kprobe_seq_start, | |
2406 | .next = kprobe_seq_next, | |
2407 | .stop = kprobe_seq_stop, | |
2408 | .show = show_kprobe_addr | |
2409 | }; | |
2410 | ||
2411 | static int kprobes_open(struct inode *inode, struct file *filp) | |
2412 | { | |
2413 | return seq_open(filp, &kprobes_seq_ops); | |
2414 | } | |
2415 | ||
2416 | static const struct file_operations debugfs_kprobes_operations = { | |
2417 | .open = kprobes_open, | |
2418 | .read = seq_read, | |
2419 | .llseek = seq_lseek, | |
2420 | .release = seq_release, | |
2421 | }; | |
2422 | ||
2423 | /* kprobes/blacklist -- shows which functions can not be probed */ | |
2424 | static void *kprobe_blacklist_seq_start(struct seq_file *m, loff_t *pos) | |
2425 | { | |
2426 | return seq_list_start(&kprobe_blacklist, *pos); | |
2427 | } | |
2428 | ||
2429 | static void *kprobe_blacklist_seq_next(struct seq_file *m, void *v, loff_t *pos) | |
2430 | { | |
2431 | return seq_list_next(v, &kprobe_blacklist, pos); | |
2432 | } | |
2433 | ||
2434 | static int kprobe_blacklist_seq_show(struct seq_file *m, void *v) | |
2435 | { | |
2436 | struct kprobe_blacklist_entry *ent = | |
2437 | list_entry(v, struct kprobe_blacklist_entry, list); | |
2438 | ||
2439 | /* | |
2440 | * If /proc/kallsyms is not showing kernel address, we won't | |
2441 | * show them here either. | |
2442 | */ | |
2443 | if (!kallsyms_show_value()) | |
2444 | seq_printf(m, "0x%px-0x%px\t%ps\n", NULL, NULL, | |
2445 | (void *)ent->start_addr); | |
2446 | else | |
2447 | seq_printf(m, "0x%px-0x%px\t%ps\n", (void *)ent->start_addr, | |
2448 | (void *)ent->end_addr, (void *)ent->start_addr); | |
2449 | return 0; | |
2450 | } | |
2451 | ||
2452 | static const struct seq_operations kprobe_blacklist_seq_ops = { | |
2453 | .start = kprobe_blacklist_seq_start, | |
2454 | .next = kprobe_blacklist_seq_next, | |
2455 | .stop = kprobe_seq_stop, /* Reuse void function */ | |
2456 | .show = kprobe_blacklist_seq_show, | |
2457 | }; | |
2458 | ||
2459 | static int kprobe_blacklist_open(struct inode *inode, struct file *filp) | |
2460 | { | |
2461 | return seq_open(filp, &kprobe_blacklist_seq_ops); | |
2462 | } | |
2463 | ||
2464 | static const struct file_operations debugfs_kprobe_blacklist_ops = { | |
2465 | .open = kprobe_blacklist_open, | |
2466 | .read = seq_read, | |
2467 | .llseek = seq_lseek, | |
2468 | .release = seq_release, | |
2469 | }; | |
2470 | ||
2471 | static void arm_all_kprobes(void) | |
2472 | { | |
2473 | struct hlist_head *head; | |
2474 | struct kprobe *p; | |
2475 | unsigned int i; | |
2476 | ||
2477 | mutex_lock(&kprobe_mutex); | |
2478 | ||
2479 | /* If kprobes are armed, just return */ | |
2480 | if (!kprobes_all_disarmed) | |
2481 | goto already_enabled; | |
2482 | ||
2483 | /* | |
2484 | * optimize_kprobe() called by arm_kprobe() checks | |
2485 | * kprobes_all_disarmed, so set kprobes_all_disarmed before | |
2486 | * arm_kprobe. | |
2487 | */ | |
2488 | kprobes_all_disarmed = false; | |
2489 | /* Arming kprobes doesn't optimize kprobe itself */ | |
2490 | for (i = 0; i < KPROBE_TABLE_SIZE; i++) { | |
2491 | head = &kprobe_table[i]; | |
2492 | hlist_for_each_entry_rcu(p, head, hlist) | |
2493 | if (!kprobe_disabled(p)) | |
2494 | arm_kprobe(p); | |
2495 | } | |
2496 | ||
2497 | printk(KERN_INFO "Kprobes globally enabled\n"); | |
2498 | ||
2499 | already_enabled: | |
2500 | mutex_unlock(&kprobe_mutex); | |
2501 | return; | |
2502 | } | |
2503 | ||
2504 | static void disarm_all_kprobes(void) | |
2505 | { | |
2506 | struct hlist_head *head; | |
2507 | struct kprobe *p; | |
2508 | unsigned int i; | |
2509 | ||
2510 | mutex_lock(&kprobe_mutex); | |
2511 | ||
2512 | /* If kprobes are already disarmed, just return */ | |
2513 | if (kprobes_all_disarmed) { | |
2514 | mutex_unlock(&kprobe_mutex); | |
2515 | return; | |
2516 | } | |
2517 | ||
2518 | kprobes_all_disarmed = true; | |
2519 | printk(KERN_INFO "Kprobes globally disabled\n"); | |
2520 | ||
2521 | for (i = 0; i < KPROBE_TABLE_SIZE; i++) { | |
2522 | head = &kprobe_table[i]; | |
2523 | hlist_for_each_entry_rcu(p, head, hlist) { | |
2524 | if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p)) | |
2525 | disarm_kprobe(p, false); | |
2526 | } | |
2527 | } | |
2528 | mutex_unlock(&kprobe_mutex); | |
2529 | ||
2530 | /* Wait for disarming all kprobes by optimizer */ | |
2531 | wait_for_kprobe_optimizer(); | |
2532 | } | |
2533 | ||
2534 | /* | |
2535 | * XXX: The debugfs bool file interface doesn't allow for callbacks | |
2536 | * when the bool state is switched. We can reuse that facility when | |
2537 | * available | |
2538 | */ | |
2539 | static ssize_t read_enabled_file_bool(struct file *file, | |
2540 | char __user *user_buf, size_t count, loff_t *ppos) | |
2541 | { | |
2542 | char buf[3]; | |
2543 | ||
2544 | if (!kprobes_all_disarmed) | |
2545 | buf[0] = '1'; | |
2546 | else | |
2547 | buf[0] = '0'; | |
2548 | buf[1] = '\n'; | |
2549 | buf[2] = 0x00; | |
2550 | return simple_read_from_buffer(user_buf, count, ppos, buf, 2); | |
2551 | } | |
2552 | ||
2553 | static ssize_t write_enabled_file_bool(struct file *file, | |
2554 | const char __user *user_buf, size_t count, loff_t *ppos) | |
2555 | { | |
2556 | char buf[32]; | |
2557 | size_t buf_size; | |
2558 | ||
2559 | buf_size = min(count, (sizeof(buf)-1)); | |
2560 | if (copy_from_user(buf, user_buf, buf_size)) | |
2561 | return -EFAULT; | |
2562 | ||
2563 | buf[buf_size] = '\0'; | |
2564 | switch (buf[0]) { | |
2565 | case 'y': | |
2566 | case 'Y': | |
2567 | case '1': | |
2568 | arm_all_kprobes(); | |
2569 | break; | |
2570 | case 'n': | |
2571 | case 'N': | |
2572 | case '0': | |
2573 | disarm_all_kprobes(); | |
2574 | break; | |
2575 | default: | |
2576 | return -EINVAL; | |
2577 | } | |
2578 | ||
2579 | return count; | |
2580 | } | |
2581 | ||
2582 | static const struct file_operations fops_kp = { | |
2583 | .read = read_enabled_file_bool, | |
2584 | .write = write_enabled_file_bool, | |
2585 | .llseek = default_llseek, | |
2586 | }; | |
2587 | ||
2588 | static int __init debugfs_kprobe_init(void) | |
2589 | { | |
2590 | struct dentry *dir, *file; | |
2591 | unsigned int value = 1; | |
2592 | ||
2593 | dir = debugfs_create_dir("kprobes", NULL); | |
2594 | if (!dir) | |
2595 | return -ENOMEM; | |
2596 | ||
2597 | file = debugfs_create_file("list", 0400, dir, NULL, | |
2598 | &debugfs_kprobes_operations); | |
2599 | if (!file) | |
2600 | goto error; | |
2601 | ||
2602 | file = debugfs_create_file("enabled", 0600, dir, | |
2603 | &value, &fops_kp); | |
2604 | if (!file) | |
2605 | goto error; | |
2606 | ||
2607 | file = debugfs_create_file("blacklist", 0400, dir, NULL, | |
2608 | &debugfs_kprobe_blacklist_ops); | |
2609 | if (!file) | |
2610 | goto error; | |
2611 | ||
2612 | return 0; | |
2613 | ||
2614 | error: | |
2615 | debugfs_remove(dir); | |
2616 | return -ENOMEM; | |
2617 | } | |
2618 | ||
2619 | late_initcall(debugfs_kprobe_init); | |
2620 | #endif /* CONFIG_DEBUG_FS */ | |
2621 | ||
2622 | module_init(init_kprobes); | |
2623 | ||
2624 | /* defined in arch/.../kernel/kprobes.c */ | |
2625 | EXPORT_SYMBOL_GPL(jprobe_return); |