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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/module.h> |
40 | #include <linux/moduleloader.h> |
41 | #include <linux/kallsyms.h> |
42 | #include <linux/freezer.h> |
43 | #include <linux/seq_file.h> |
44 | #include <linux/debugfs.h> |
45 | #include <linux/sysctl.h> |
46 | #include <linux/kdebug.h> |
47 | #include <linux/memory.h> |
48 | #include <linux/ftrace.h> |
49 | #include <linux/cpu.h> |
50 | #include <linux/jump_label.h> |
51 | |
52 | #include <asm-generic/sections.h> |
53 | #include <asm/cacheflush.h> |
54 | #include <asm/errno.h> |
55 | #include <asm/uaccess.h> |
56 | |
57 | #define KPROBE_HASH_BITS 6 |
58 | #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS) |
59 | |
60 | |
61 | /* |
62 | * Some oddball architectures like 64bit powerpc have function descriptors |
63 | * so this must be overridable. |
64 | */ |
65 | #ifndef kprobe_lookup_name |
66 | #define kprobe_lookup_name(name, addr) \ |
67 | addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name))) |
68 | #endif |
69 | |
70 | static int kprobes_initialized; |
71 | static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; |
72 | static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE]; |
73 | |
74 | /* NOTE: change this value only with kprobe_mutex held */ |
75 | static bool kprobes_all_disarmed; |
76 | |
77 | /* This protects kprobe_table and optimizing_list */ |
78 | static DEFINE_MUTEX(kprobe_mutex); |
79 | static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL; |
80 | static struct { |
81 | spinlock_t lock ____cacheline_aligned_in_smp; |
82 | } kretprobe_table_locks[KPROBE_TABLE_SIZE]; |
83 | |
84 | static spinlock_t *kretprobe_table_lock_ptr(unsigned long hash) |
85 | { |
86 | return &(kretprobe_table_locks[hash].lock); |
87 | } |
88 | |
89 | /* |
90 | * Normally, functions that we'd want to prohibit kprobes in, are marked |
91 | * __kprobes. But, there are cases where such functions already belong to |
92 | * a different section (__sched for preempt_schedule) |
93 | * |
94 | * For such cases, we now have a blacklist |
95 | */ |
96 | static struct kprobe_blackpoint kprobe_blacklist[] = { |
97 | {"preempt_schedule",}, |
98 | {"native_get_debugreg",}, |
99 | {"irq_entries_start",}, |
100 | {"common_interrupt",}, |
101 | {"mcount",}, /* mcount can be called from everywhere */ |
102 | {NULL} /* Terminator */ |
103 | }; |
104 | |
105 | #ifdef __ARCH_WANT_KPROBES_INSN_SLOT |
106 | /* |
107 | * kprobe->ainsn.insn points to the copy of the instruction to be |
108 | * single-stepped. x86_64, POWER4 and above have no-exec support and |
109 | * stepping on the instruction on a vmalloced/kmalloced/data page |
110 | * is a recipe for disaster |
111 | */ |
112 | struct kprobe_insn_page { |
113 | struct list_head list; |
114 | kprobe_opcode_t *insns; /* Page of instruction slots */ |
115 | int nused; |
116 | int ngarbage; |
117 | char slot_used[]; |
118 | }; |
119 | |
120 | #define KPROBE_INSN_PAGE_SIZE(slots) \ |
121 | (offsetof(struct kprobe_insn_page, slot_used) + \ |
122 | (sizeof(char) * (slots))) |
123 | |
124 | struct kprobe_insn_cache { |
125 | struct list_head pages; /* list of kprobe_insn_page */ |
126 | size_t insn_size; /* size of instruction slot */ |
127 | int nr_garbage; |
128 | }; |
129 | |
130 | static int slots_per_page(struct kprobe_insn_cache *c) |
131 | { |
132 | return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t)); |
133 | } |
134 | |
135 | enum kprobe_slot_state { |
136 | SLOT_CLEAN = 0, |
137 | SLOT_DIRTY = 1, |
138 | SLOT_USED = 2, |
139 | }; |
140 | |
141 | static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_slots */ |
142 | static struct kprobe_insn_cache kprobe_insn_slots = { |
143 | .pages = LIST_HEAD_INIT(kprobe_insn_slots.pages), |
144 | .insn_size = MAX_INSN_SIZE, |
145 | .nr_garbage = 0, |
146 | }; |
147 | static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c); |
148 | |
149 | /** |
150 | * __get_insn_slot() - Find a slot on an executable page for an instruction. |
151 | * We allocate an executable page if there's no room on existing ones. |
152 | */ |
153 | static kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c) |
154 | { |
155 | struct kprobe_insn_page *kip; |
156 | |
157 | retry: |
158 | list_for_each_entry(kip, &c->pages, list) { |
159 | if (kip->nused < slots_per_page(c)) { |
160 | int i; |
161 | for (i = 0; i < slots_per_page(c); i++) { |
162 | if (kip->slot_used[i] == SLOT_CLEAN) { |
163 | kip->slot_used[i] = SLOT_USED; |
164 | kip->nused++; |
165 | return kip->insns + (i * c->insn_size); |
166 | } |
167 | } |
168 | /* kip->nused is broken. Fix it. */ |
169 | kip->nused = slots_per_page(c); |
170 | WARN_ON(1); |
171 | } |
172 | } |
173 | |
174 | /* If there are any garbage slots, collect it and try again. */ |
175 | if (c->nr_garbage && collect_garbage_slots(c) == 0) |
176 | goto retry; |
177 | |
178 | /* All out of space. Need to allocate a new page. */ |
179 | kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL); |
180 | if (!kip) |
181 | return NULL; |
182 | |
183 | /* |
184 | * Use module_alloc so this page is within +/- 2GB of where the |
185 | * kernel image and loaded module images reside. This is required |
186 | * so x86_64 can correctly handle the %rip-relative fixups. |
187 | */ |
188 | kip->insns = module_alloc(PAGE_SIZE); |
189 | if (!kip->insns) { |
190 | kfree(kip); |
191 | return NULL; |
192 | } |
193 | INIT_LIST_HEAD(&kip->list); |
194 | memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c)); |
195 | kip->slot_used[0] = SLOT_USED; |
196 | kip->nused = 1; |
197 | kip->ngarbage = 0; |
198 | list_add(&kip->list, &c->pages); |
199 | return kip->insns; |
200 | } |
201 | |
202 | |
203 | kprobe_opcode_t __kprobes *get_insn_slot(void) |
204 | { |
205 | kprobe_opcode_t *ret = NULL; |
206 | |
207 | mutex_lock(&kprobe_insn_mutex); |
208 | ret = __get_insn_slot(&kprobe_insn_slots); |
209 | mutex_unlock(&kprobe_insn_mutex); |
210 | |
211 | return ret; |
212 | } |
213 | |
214 | /* Return 1 if all garbages are collected, otherwise 0. */ |
215 | static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx) |
216 | { |
217 | kip->slot_used[idx] = SLOT_CLEAN; |
218 | kip->nused--; |
219 | if (kip->nused == 0) { |
220 | /* |
221 | * Page is no longer in use. Free it unless |
222 | * it's the last one. We keep the last one |
223 | * so as not to have to set it up again the |
224 | * next time somebody inserts a probe. |
225 | */ |
226 | if (!list_is_singular(&kip->list)) { |
227 | list_del(&kip->list); |
228 | module_free(NULL, kip->insns); |
229 | kfree(kip); |
230 | } |
231 | return 1; |
232 | } |
233 | return 0; |
234 | } |
235 | |
236 | static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c) |
237 | { |
238 | struct kprobe_insn_page *kip, *next; |
239 | |
240 | /* Ensure no-one is interrupted on the garbages */ |
241 | synchronize_sched(); |
242 | |
243 | list_for_each_entry_safe(kip, next, &c->pages, list) { |
244 | int i; |
245 | if (kip->ngarbage == 0) |
246 | continue; |
247 | kip->ngarbage = 0; /* we will collect all garbages */ |
248 | for (i = 0; i < slots_per_page(c); i++) { |
249 | if (kip->slot_used[i] == SLOT_DIRTY && |
250 | collect_one_slot(kip, i)) |
251 | break; |
252 | } |
253 | } |
254 | c->nr_garbage = 0; |
255 | return 0; |
256 | } |
257 | |
258 | static void __kprobes __free_insn_slot(struct kprobe_insn_cache *c, |
259 | kprobe_opcode_t *slot, int dirty) |
260 | { |
261 | struct kprobe_insn_page *kip; |
262 | |
263 | list_for_each_entry(kip, &c->pages, list) { |
264 | long idx = ((long)slot - (long)kip->insns) / |
265 | (c->insn_size * sizeof(kprobe_opcode_t)); |
266 | if (idx >= 0 && idx < slots_per_page(c)) { |
267 | WARN_ON(kip->slot_used[idx] != SLOT_USED); |
268 | if (dirty) { |
269 | kip->slot_used[idx] = SLOT_DIRTY; |
270 | kip->ngarbage++; |
271 | if (++c->nr_garbage > slots_per_page(c)) |
272 | collect_garbage_slots(c); |
273 | } else |
274 | collect_one_slot(kip, idx); |
275 | return; |
276 | } |
277 | } |
278 | /* Could not free this slot. */ |
279 | WARN_ON(1); |
280 | } |
281 | |
282 | void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty) |
283 | { |
284 | mutex_lock(&kprobe_insn_mutex); |
285 | __free_insn_slot(&kprobe_insn_slots, slot, dirty); |
286 | mutex_unlock(&kprobe_insn_mutex); |
287 | } |
288 | #ifdef CONFIG_OPTPROBES |
289 | /* For optimized_kprobe buffer */ |
290 | static DEFINE_MUTEX(kprobe_optinsn_mutex); /* Protects kprobe_optinsn_slots */ |
291 | static struct kprobe_insn_cache kprobe_optinsn_slots = { |
292 | .pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages), |
293 | /* .insn_size is initialized later */ |
294 | .nr_garbage = 0, |
295 | }; |
296 | /* Get a slot for optimized_kprobe buffer */ |
297 | kprobe_opcode_t __kprobes *get_optinsn_slot(void) |
298 | { |
299 | kprobe_opcode_t *ret = NULL; |
300 | |
301 | mutex_lock(&kprobe_optinsn_mutex); |
302 | ret = __get_insn_slot(&kprobe_optinsn_slots); |
303 | mutex_unlock(&kprobe_optinsn_mutex); |
304 | |
305 | return ret; |
306 | } |
307 | |
308 | void __kprobes free_optinsn_slot(kprobe_opcode_t * slot, int dirty) |
309 | { |
310 | mutex_lock(&kprobe_optinsn_mutex); |
311 | __free_insn_slot(&kprobe_optinsn_slots, slot, dirty); |
312 | mutex_unlock(&kprobe_optinsn_mutex); |
313 | } |
314 | #endif |
315 | #endif |
316 | |
317 | /* We have preemption disabled.. so it is safe to use __ versions */ |
318 | static inline void set_kprobe_instance(struct kprobe *kp) |
319 | { |
320 | __get_cpu_var(kprobe_instance) = kp; |
321 | } |
322 | |
323 | static inline void reset_kprobe_instance(void) |
324 | { |
325 | __get_cpu_var(kprobe_instance) = NULL; |
326 | } |
327 | |
328 | /* |
329 | * This routine is called either: |
330 | * - under the kprobe_mutex - during kprobe_[un]register() |
331 | * OR |
332 | * - with preemption disabled - from arch/xxx/kernel/kprobes.c |
333 | */ |
334 | struct kprobe __kprobes *get_kprobe(void *addr) |
335 | { |
336 | struct hlist_head *head; |
337 | struct hlist_node *node; |
338 | struct kprobe *p; |
339 | |
340 | head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)]; |
341 | hlist_for_each_entry_rcu(p, node, head, hlist) { |
342 | if (p->addr == addr) |
343 | return p; |
344 | } |
345 | |
346 | return NULL; |
347 | } |
348 | |
349 | static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs); |
350 | |
351 | /* Return true if the kprobe is an aggregator */ |
352 | static inline int kprobe_aggrprobe(struct kprobe *p) |
353 | { |
354 | return p->pre_handler == aggr_pre_handler; |
355 | } |
356 | |
357 | /* |
358 | * Keep all fields in the kprobe consistent |
359 | */ |
360 | static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p) |
361 | { |
362 | memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t)); |
363 | memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn)); |
364 | } |
365 | |
366 | #ifdef CONFIG_OPTPROBES |
367 | /* NOTE: change this value only with kprobe_mutex held */ |
368 | static bool kprobes_allow_optimization; |
369 | |
370 | /* |
371 | * Call all pre_handler on the list, but ignores its return value. |
372 | * This must be called from arch-dep optimized caller. |
373 | */ |
374 | void __kprobes opt_pre_handler(struct kprobe *p, struct pt_regs *regs) |
375 | { |
376 | struct kprobe *kp; |
377 | |
378 | list_for_each_entry_rcu(kp, &p->list, list) { |
379 | if (kp->pre_handler && likely(!kprobe_disabled(kp))) { |
380 | set_kprobe_instance(kp); |
381 | kp->pre_handler(kp, regs); |
382 | } |
383 | reset_kprobe_instance(); |
384 | } |
385 | } |
386 | |
387 | /* Return true(!0) if the kprobe is ready for optimization. */ |
388 | static inline int kprobe_optready(struct kprobe *p) |
389 | { |
390 | struct optimized_kprobe *op; |
391 | |
392 | if (kprobe_aggrprobe(p)) { |
393 | op = container_of(p, struct optimized_kprobe, kp); |
394 | return arch_prepared_optinsn(&op->optinsn); |
395 | } |
396 | |
397 | return 0; |
398 | } |
399 | |
400 | /* |
401 | * Return an optimized kprobe whose optimizing code replaces |
402 | * instructions including addr (exclude breakpoint). |
403 | */ |
404 | static struct kprobe *__kprobes get_optimized_kprobe(unsigned long addr) |
405 | { |
406 | int i; |
407 | struct kprobe *p = NULL; |
408 | struct optimized_kprobe *op; |
409 | |
410 | /* Don't check i == 0, since that is a breakpoint case. */ |
411 | for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH; i++) |
412 | p = get_kprobe((void *)(addr - i)); |
413 | |
414 | if (p && kprobe_optready(p)) { |
415 | op = container_of(p, struct optimized_kprobe, kp); |
416 | if (arch_within_optimized_kprobe(op, addr)) |
417 | return p; |
418 | } |
419 | |
420 | return NULL; |
421 | } |
422 | |
423 | /* Optimization staging list, protected by kprobe_mutex */ |
424 | static LIST_HEAD(optimizing_list); |
425 | |
426 | static void kprobe_optimizer(struct work_struct *work); |
427 | static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer); |
428 | #define OPTIMIZE_DELAY 5 |
429 | |
430 | /* Kprobe jump optimizer */ |
431 | static __kprobes void kprobe_optimizer(struct work_struct *work) |
432 | { |
433 | struct optimized_kprobe *op, *tmp; |
434 | |
435 | /* Lock modules while optimizing kprobes */ |
436 | mutex_lock(&module_mutex); |
437 | mutex_lock(&kprobe_mutex); |
438 | if (kprobes_all_disarmed || !kprobes_allow_optimization) |
439 | goto end; |
440 | |
441 | /* |
442 | * Wait for quiesence period to ensure all running interrupts |
443 | * are done. Because optprobe may modify multiple instructions |
444 | * there is a chance that Nth instruction is interrupted. In that |
445 | * case, running interrupt can return to 2nd-Nth byte of jump |
446 | * instruction. This wait is for avoiding it. |
447 | */ |
448 | synchronize_sched(); |
449 | |
450 | /* |
451 | * The optimization/unoptimization refers online_cpus via |
452 | * stop_machine() and cpu-hotplug modifies online_cpus. |
453 | * And same time, text_mutex will be held in cpu-hotplug and here. |
454 | * This combination can cause a deadlock (cpu-hotplug try to lock |
455 | * text_mutex but stop_machine can not be done because online_cpus |
456 | * has been changed) |
457 | * To avoid this deadlock, we need to call get_online_cpus() |
458 | * for preventing cpu-hotplug outside of text_mutex locking. |
459 | */ |
460 | get_online_cpus(); |
461 | mutex_lock(&text_mutex); |
462 | list_for_each_entry_safe(op, tmp, &optimizing_list, list) { |
463 | WARN_ON(kprobe_disabled(&op->kp)); |
464 | if (arch_optimize_kprobe(op) < 0) |
465 | op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED; |
466 | list_del_init(&op->list); |
467 | } |
468 | mutex_unlock(&text_mutex); |
469 | put_online_cpus(); |
470 | end: |
471 | mutex_unlock(&kprobe_mutex); |
472 | mutex_unlock(&module_mutex); |
473 | } |
474 | |
475 | /* Optimize kprobe if p is ready to be optimized */ |
476 | static __kprobes void optimize_kprobe(struct kprobe *p) |
477 | { |
478 | struct optimized_kprobe *op; |
479 | |
480 | /* Check if the kprobe is disabled or not ready for optimization. */ |
481 | if (!kprobe_optready(p) || !kprobes_allow_optimization || |
482 | (kprobe_disabled(p) || kprobes_all_disarmed)) |
483 | return; |
484 | |
485 | /* Both of break_handler and post_handler are not supported. */ |
486 | if (p->break_handler || p->post_handler) |
487 | return; |
488 | |
489 | op = container_of(p, struct optimized_kprobe, kp); |
490 | |
491 | /* Check there is no other kprobes at the optimized instructions */ |
492 | if (arch_check_optimized_kprobe(op) < 0) |
493 | return; |
494 | |
495 | /* Check if it is already optimized. */ |
496 | if (op->kp.flags & KPROBE_FLAG_OPTIMIZED) |
497 | return; |
498 | |
499 | op->kp.flags |= KPROBE_FLAG_OPTIMIZED; |
500 | list_add(&op->list, &optimizing_list); |
501 | if (!delayed_work_pending(&optimizing_work)) |
502 | schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY); |
503 | } |
504 | |
505 | /* Unoptimize a kprobe if p is optimized */ |
506 | static __kprobes void unoptimize_kprobe(struct kprobe *p) |
507 | { |
508 | struct optimized_kprobe *op; |
509 | |
510 | if ((p->flags & KPROBE_FLAG_OPTIMIZED) && kprobe_aggrprobe(p)) { |
511 | op = container_of(p, struct optimized_kprobe, kp); |
512 | if (!list_empty(&op->list)) |
513 | /* Dequeue from the optimization queue */ |
514 | list_del_init(&op->list); |
515 | else |
516 | /* Replace jump with break */ |
517 | arch_unoptimize_kprobe(op); |
518 | op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED; |
519 | } |
520 | } |
521 | |
522 | /* Remove optimized instructions */ |
523 | static void __kprobes kill_optimized_kprobe(struct kprobe *p) |
524 | { |
525 | struct optimized_kprobe *op; |
526 | |
527 | op = container_of(p, struct optimized_kprobe, kp); |
528 | if (!list_empty(&op->list)) { |
529 | /* Dequeue from the optimization queue */ |
530 | list_del_init(&op->list); |
531 | op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED; |
532 | } |
533 | /* Don't unoptimize, because the target code will be freed. */ |
534 | arch_remove_optimized_kprobe(op); |
535 | } |
536 | |
537 | /* Try to prepare optimized instructions */ |
538 | static __kprobes void prepare_optimized_kprobe(struct kprobe *p) |
539 | { |
540 | struct optimized_kprobe *op; |
541 | |
542 | op = container_of(p, struct optimized_kprobe, kp); |
543 | arch_prepare_optimized_kprobe(op); |
544 | } |
545 | |
546 | /* Free optimized instructions and optimized_kprobe */ |
547 | static __kprobes void free_aggr_kprobe(struct kprobe *p) |
548 | { |
549 | struct optimized_kprobe *op; |
550 | |
551 | op = container_of(p, struct optimized_kprobe, kp); |
552 | arch_remove_optimized_kprobe(op); |
553 | kfree(op); |
554 | } |
555 | |
556 | /* Allocate new optimized_kprobe and try to prepare optimized instructions */ |
557 | static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p) |
558 | { |
559 | struct optimized_kprobe *op; |
560 | |
561 | op = kzalloc(sizeof(struct optimized_kprobe), GFP_KERNEL); |
562 | if (!op) |
563 | return NULL; |
564 | |
565 | INIT_LIST_HEAD(&op->list); |
566 | op->kp.addr = p->addr; |
567 | arch_prepare_optimized_kprobe(op); |
568 | |
569 | return &op->kp; |
570 | } |
571 | |
572 | static void __kprobes init_aggr_kprobe(struct kprobe *ap, struct kprobe *p); |
573 | |
574 | /* |
575 | * Prepare an optimized_kprobe and optimize it |
576 | * NOTE: p must be a normal registered kprobe |
577 | */ |
578 | static __kprobes void try_to_optimize_kprobe(struct kprobe *p) |
579 | { |
580 | struct kprobe *ap; |
581 | struct optimized_kprobe *op; |
582 | |
583 | ap = alloc_aggr_kprobe(p); |
584 | if (!ap) |
585 | return; |
586 | |
587 | op = container_of(ap, struct optimized_kprobe, kp); |
588 | if (!arch_prepared_optinsn(&op->optinsn)) { |
589 | /* If failed to setup optimizing, fallback to kprobe */ |
590 | free_aggr_kprobe(ap); |
591 | return; |
592 | } |
593 | |
594 | init_aggr_kprobe(ap, p); |
595 | optimize_kprobe(ap); |
596 | } |
597 | |
598 | #ifdef CONFIG_SYSCTL |
599 | /* This should be called with kprobe_mutex locked */ |
600 | static void __kprobes optimize_all_kprobes(void) |
601 | { |
602 | struct hlist_head *head; |
603 | struct hlist_node *node; |
604 | struct kprobe *p; |
605 | unsigned int i; |
606 | |
607 | /* If optimization is already allowed, just return */ |
608 | if (kprobes_allow_optimization) |
609 | return; |
610 | |
611 | kprobes_allow_optimization = true; |
612 | for (i = 0; i < KPROBE_TABLE_SIZE; i++) { |
613 | head = &kprobe_table[i]; |
614 | hlist_for_each_entry_rcu(p, node, head, hlist) |
615 | if (!kprobe_disabled(p)) |
616 | optimize_kprobe(p); |
617 | } |
618 | printk(KERN_INFO "Kprobes globally optimized\n"); |
619 | } |
620 | |
621 | /* This should be called with kprobe_mutex locked */ |
622 | static void __kprobes unoptimize_all_kprobes(void) |
623 | { |
624 | struct hlist_head *head; |
625 | struct hlist_node *node; |
626 | struct kprobe *p; |
627 | unsigned int i; |
628 | |
629 | /* If optimization is already prohibited, just return */ |
630 | if (!kprobes_allow_optimization) |
631 | return; |
632 | |
633 | kprobes_allow_optimization = false; |
634 | printk(KERN_INFO "Kprobes globally unoptimized\n"); |
635 | get_online_cpus(); /* For avoiding text_mutex deadlock */ |
636 | mutex_lock(&text_mutex); |
637 | for (i = 0; i < KPROBE_TABLE_SIZE; i++) { |
638 | head = &kprobe_table[i]; |
639 | hlist_for_each_entry_rcu(p, node, head, hlist) { |
640 | if (!kprobe_disabled(p)) |
641 | unoptimize_kprobe(p); |
642 | } |
643 | } |
644 | |
645 | mutex_unlock(&text_mutex); |
646 | put_online_cpus(); |
647 | /* Allow all currently running kprobes to complete */ |
648 | synchronize_sched(); |
649 | } |
650 | |
651 | int sysctl_kprobes_optimization; |
652 | int proc_kprobes_optimization_handler(struct ctl_table *table, int write, |
653 | void __user *buffer, size_t *length, |
654 | loff_t *ppos) |
655 | { |
656 | int ret; |
657 | |
658 | mutex_lock(&kprobe_mutex); |
659 | sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0; |
660 | ret = proc_dointvec_minmax(table, write, buffer, length, ppos); |
661 | |
662 | if (sysctl_kprobes_optimization) |
663 | optimize_all_kprobes(); |
664 | else |
665 | unoptimize_all_kprobes(); |
666 | mutex_unlock(&kprobe_mutex); |
667 | |
668 | return ret; |
669 | } |
670 | #endif /* CONFIG_SYSCTL */ |
671 | |
672 | static void __kprobes __arm_kprobe(struct kprobe *p) |
673 | { |
674 | struct kprobe *old_p; |
675 | |
676 | /* Check collision with other optimized kprobes */ |
677 | old_p = get_optimized_kprobe((unsigned long)p->addr); |
678 | if (unlikely(old_p)) |
679 | unoptimize_kprobe(old_p); /* Fallback to unoptimized kprobe */ |
680 | |
681 | arch_arm_kprobe(p); |
682 | optimize_kprobe(p); /* Try to optimize (add kprobe to a list) */ |
683 | } |
684 | |
685 | static void __kprobes __disarm_kprobe(struct kprobe *p) |
686 | { |
687 | struct kprobe *old_p; |
688 | |
689 | unoptimize_kprobe(p); /* Try to unoptimize */ |
690 | arch_disarm_kprobe(p); |
691 | |
692 | /* If another kprobe was blocked, optimize it. */ |
693 | old_p = get_optimized_kprobe((unsigned long)p->addr); |
694 | if (unlikely(old_p)) |
695 | optimize_kprobe(old_p); |
696 | } |
697 | |
698 | #else /* !CONFIG_OPTPROBES */ |
699 | |
700 | #define optimize_kprobe(p) do {} while (0) |
701 | #define unoptimize_kprobe(p) do {} while (0) |
702 | #define kill_optimized_kprobe(p) do {} while (0) |
703 | #define prepare_optimized_kprobe(p) do {} while (0) |
704 | #define try_to_optimize_kprobe(p) do {} while (0) |
705 | #define __arm_kprobe(p) arch_arm_kprobe(p) |
706 | #define __disarm_kprobe(p) arch_disarm_kprobe(p) |
707 | |
708 | static __kprobes void free_aggr_kprobe(struct kprobe *p) |
709 | { |
710 | kfree(p); |
711 | } |
712 | |
713 | static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p) |
714 | { |
715 | return kzalloc(sizeof(struct kprobe), GFP_KERNEL); |
716 | } |
717 | #endif /* CONFIG_OPTPROBES */ |
718 | |
719 | /* Arm a kprobe with text_mutex */ |
720 | static void __kprobes arm_kprobe(struct kprobe *kp) |
721 | { |
722 | /* |
723 | * Here, since __arm_kprobe() doesn't use stop_machine(), |
724 | * this doesn't cause deadlock on text_mutex. So, we don't |
725 | * need get_online_cpus(). |
726 | */ |
727 | mutex_lock(&text_mutex); |
728 | __arm_kprobe(kp); |
729 | mutex_unlock(&text_mutex); |
730 | } |
731 | |
732 | /* Disarm a kprobe with text_mutex */ |
733 | static void __kprobes disarm_kprobe(struct kprobe *kp) |
734 | { |
735 | get_online_cpus(); /* For avoiding text_mutex deadlock */ |
736 | mutex_lock(&text_mutex); |
737 | __disarm_kprobe(kp); |
738 | mutex_unlock(&text_mutex); |
739 | put_online_cpus(); |
740 | } |
741 | |
742 | /* |
743 | * Aggregate handlers for multiple kprobes support - these handlers |
744 | * take care of invoking the individual kprobe handlers on p->list |
745 | */ |
746 | static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs) |
747 | { |
748 | struct kprobe *kp; |
749 | |
750 | list_for_each_entry_rcu(kp, &p->list, list) { |
751 | if (kp->pre_handler && likely(!kprobe_disabled(kp))) { |
752 | set_kprobe_instance(kp); |
753 | if (kp->pre_handler(kp, regs)) |
754 | return 1; |
755 | } |
756 | reset_kprobe_instance(); |
757 | } |
758 | return 0; |
759 | } |
760 | |
761 | static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs, |
762 | unsigned long flags) |
763 | { |
764 | struct kprobe *kp; |
765 | |
766 | list_for_each_entry_rcu(kp, &p->list, list) { |
767 | if (kp->post_handler && likely(!kprobe_disabled(kp))) { |
768 | set_kprobe_instance(kp); |
769 | kp->post_handler(kp, regs, flags); |
770 | reset_kprobe_instance(); |
771 | } |
772 | } |
773 | } |
774 | |
775 | static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs, |
776 | int trapnr) |
777 | { |
778 | struct kprobe *cur = __get_cpu_var(kprobe_instance); |
779 | |
780 | /* |
781 | * if we faulted "during" the execution of a user specified |
782 | * probe handler, invoke just that probe's fault handler |
783 | */ |
784 | if (cur && cur->fault_handler) { |
785 | if (cur->fault_handler(cur, regs, trapnr)) |
786 | return 1; |
787 | } |
788 | return 0; |
789 | } |
790 | |
791 | static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs) |
792 | { |
793 | struct kprobe *cur = __get_cpu_var(kprobe_instance); |
794 | int ret = 0; |
795 | |
796 | if (cur && cur->break_handler) { |
797 | if (cur->break_handler(cur, regs)) |
798 | ret = 1; |
799 | } |
800 | reset_kprobe_instance(); |
801 | return ret; |
802 | } |
803 | |
804 | /* Walks the list and increments nmissed count for multiprobe case */ |
805 | void __kprobes kprobes_inc_nmissed_count(struct kprobe *p) |
806 | { |
807 | struct kprobe *kp; |
808 | if (!kprobe_aggrprobe(p)) { |
809 | p->nmissed++; |
810 | } else { |
811 | list_for_each_entry_rcu(kp, &p->list, list) |
812 | kp->nmissed++; |
813 | } |
814 | return; |
815 | } |
816 | |
817 | void __kprobes recycle_rp_inst(struct kretprobe_instance *ri, |
818 | struct hlist_head *head) |
819 | { |
820 | struct kretprobe *rp = ri->rp; |
821 | |
822 | /* remove rp inst off the rprobe_inst_table */ |
823 | hlist_del(&ri->hlist); |
824 | INIT_HLIST_NODE(&ri->hlist); |
825 | if (likely(rp)) { |
826 | spin_lock(&rp->lock); |
827 | hlist_add_head(&ri->hlist, &rp->free_instances); |
828 | spin_unlock(&rp->lock); |
829 | } else |
830 | /* Unregistering */ |
831 | hlist_add_head(&ri->hlist, head); |
832 | } |
833 | |
834 | void __kprobes kretprobe_hash_lock(struct task_struct *tsk, |
835 | struct hlist_head **head, unsigned long *flags) |
836 | __acquires(hlist_lock) |
837 | { |
838 | unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS); |
839 | spinlock_t *hlist_lock; |
840 | |
841 | *head = &kretprobe_inst_table[hash]; |
842 | hlist_lock = kretprobe_table_lock_ptr(hash); |
843 | spin_lock_irqsave(hlist_lock, *flags); |
844 | } |
845 | |
846 | static void __kprobes kretprobe_table_lock(unsigned long hash, |
847 | unsigned long *flags) |
848 | __acquires(hlist_lock) |
849 | { |
850 | spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash); |
851 | spin_lock_irqsave(hlist_lock, *flags); |
852 | } |
853 | |
854 | void __kprobes kretprobe_hash_unlock(struct task_struct *tsk, |
855 | unsigned long *flags) |
856 | __releases(hlist_lock) |
857 | { |
858 | unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS); |
859 | spinlock_t *hlist_lock; |
860 | |
861 | hlist_lock = kretprobe_table_lock_ptr(hash); |
862 | spin_unlock_irqrestore(hlist_lock, *flags); |
863 | } |
864 | |
865 | static void __kprobes kretprobe_table_unlock(unsigned long hash, |
866 | unsigned long *flags) |
867 | __releases(hlist_lock) |
868 | { |
869 | spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash); |
870 | spin_unlock_irqrestore(hlist_lock, *flags); |
871 | } |
872 | |
873 | /* |
874 | * This function is called from finish_task_switch when task tk becomes dead, |
875 | * so that we can recycle any function-return probe instances associated |
876 | * with this task. These left over instances represent probed functions |
877 | * that have been called but will never return. |
878 | */ |
879 | void __kprobes kprobe_flush_task(struct task_struct *tk) |
880 | { |
881 | struct kretprobe_instance *ri; |
882 | struct hlist_head *head, empty_rp; |
883 | struct hlist_node *node, *tmp; |
884 | unsigned long hash, flags = 0; |
885 | |
886 | if (unlikely(!kprobes_initialized)) |
887 | /* Early boot. kretprobe_table_locks not yet initialized. */ |
888 | return; |
889 | |
890 | hash = hash_ptr(tk, KPROBE_HASH_BITS); |
891 | head = &kretprobe_inst_table[hash]; |
892 | kretprobe_table_lock(hash, &flags); |
893 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { |
894 | if (ri->task == tk) |
895 | recycle_rp_inst(ri, &empty_rp); |
896 | } |
897 | kretprobe_table_unlock(hash, &flags); |
898 | INIT_HLIST_HEAD(&empty_rp); |
899 | hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { |
900 | hlist_del(&ri->hlist); |
901 | kfree(ri); |
902 | } |
903 | } |
904 | |
905 | static inline void free_rp_inst(struct kretprobe *rp) |
906 | { |
907 | struct kretprobe_instance *ri; |
908 | struct hlist_node *pos, *next; |
909 | |
910 | hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, hlist) { |
911 | hlist_del(&ri->hlist); |
912 | kfree(ri); |
913 | } |
914 | } |
915 | |
916 | static void __kprobes cleanup_rp_inst(struct kretprobe *rp) |
917 | { |
918 | unsigned long flags, hash; |
919 | struct kretprobe_instance *ri; |
920 | struct hlist_node *pos, *next; |
921 | struct hlist_head *head; |
922 | |
923 | /* No race here */ |
924 | for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) { |
925 | kretprobe_table_lock(hash, &flags); |
926 | head = &kretprobe_inst_table[hash]; |
927 | hlist_for_each_entry_safe(ri, pos, next, head, hlist) { |
928 | if (ri->rp == rp) |
929 | ri->rp = NULL; |
930 | } |
931 | kretprobe_table_unlock(hash, &flags); |
932 | } |
933 | free_rp_inst(rp); |
934 | } |
935 | |
936 | /* |
937 | * Add the new probe to ap->list. Fail if this is the |
938 | * second jprobe at the address - two jprobes can't coexist |
939 | */ |
940 | static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p) |
941 | { |
942 | BUG_ON(kprobe_gone(ap) || kprobe_gone(p)); |
943 | |
944 | if (p->break_handler || p->post_handler) |
945 | unoptimize_kprobe(ap); /* Fall back to normal kprobe */ |
946 | |
947 | if (p->break_handler) { |
948 | if (ap->break_handler) |
949 | return -EEXIST; |
950 | list_add_tail_rcu(&p->list, &ap->list); |
951 | ap->break_handler = aggr_break_handler; |
952 | } else |
953 | list_add_rcu(&p->list, &ap->list); |
954 | if (p->post_handler && !ap->post_handler) |
955 | ap->post_handler = aggr_post_handler; |
956 | |
957 | if (kprobe_disabled(ap) && !kprobe_disabled(p)) { |
958 | ap->flags &= ~KPROBE_FLAG_DISABLED; |
959 | if (!kprobes_all_disarmed) |
960 | /* Arm the breakpoint again. */ |
961 | __arm_kprobe(ap); |
962 | } |
963 | return 0; |
964 | } |
965 | |
966 | /* |
967 | * Fill in the required fields of the "manager kprobe". Replace the |
968 | * earlier kprobe in the hlist with the manager kprobe |
969 | */ |
970 | static void __kprobes init_aggr_kprobe(struct kprobe *ap, struct kprobe *p) |
971 | { |
972 | /* Copy p's insn slot to ap */ |
973 | copy_kprobe(p, ap); |
974 | flush_insn_slot(ap); |
975 | ap->addr = p->addr; |
976 | ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED; |
977 | ap->pre_handler = aggr_pre_handler; |
978 | ap->fault_handler = aggr_fault_handler; |
979 | /* We don't care the kprobe which has gone. */ |
980 | if (p->post_handler && !kprobe_gone(p)) |
981 | ap->post_handler = aggr_post_handler; |
982 | if (p->break_handler && !kprobe_gone(p)) |
983 | ap->break_handler = aggr_break_handler; |
984 | |
985 | INIT_LIST_HEAD(&ap->list); |
986 | INIT_HLIST_NODE(&ap->hlist); |
987 | |
988 | list_add_rcu(&p->list, &ap->list); |
989 | hlist_replace_rcu(&p->hlist, &ap->hlist); |
990 | } |
991 | |
992 | /* |
993 | * This is the second or subsequent kprobe at the address - handle |
994 | * the intricacies |
995 | */ |
996 | static int __kprobes register_aggr_kprobe(struct kprobe *old_p, |
997 | struct kprobe *p) |
998 | { |
999 | int ret = 0; |
1000 | struct kprobe *ap = old_p; |
1001 | |
1002 | if (!kprobe_aggrprobe(old_p)) { |
1003 | /* If old_p is not an aggr_kprobe, create new aggr_kprobe. */ |
1004 | ap = alloc_aggr_kprobe(old_p); |
1005 | if (!ap) |
1006 | return -ENOMEM; |
1007 | init_aggr_kprobe(ap, old_p); |
1008 | } |
1009 | |
1010 | if (kprobe_gone(ap)) { |
1011 | /* |
1012 | * Attempting to insert new probe at the same location that |
1013 | * had a probe in the module vaddr area which already |
1014 | * freed. So, the instruction slot has already been |
1015 | * released. We need a new slot for the new probe. |
1016 | */ |
1017 | ret = arch_prepare_kprobe(ap); |
1018 | if (ret) |
1019 | /* |
1020 | * Even if fail to allocate new slot, don't need to |
1021 | * free aggr_probe. It will be used next time, or |
1022 | * freed by unregister_kprobe. |
1023 | */ |
1024 | return ret; |
1025 | |
1026 | /* Prepare optimized instructions if possible. */ |
1027 | prepare_optimized_kprobe(ap); |
1028 | |
1029 | /* |
1030 | * Clear gone flag to prevent allocating new slot again, and |
1031 | * set disabled flag because it is not armed yet. |
1032 | */ |
1033 | ap->flags = (ap->flags & ~KPROBE_FLAG_GONE) |
1034 | | KPROBE_FLAG_DISABLED; |
1035 | } |
1036 | |
1037 | /* Copy ap's insn slot to p */ |
1038 | copy_kprobe(ap, p); |
1039 | return add_new_kprobe(ap, p); |
1040 | } |
1041 | |
1042 | /* Try to disable aggr_kprobe, and return 1 if succeeded.*/ |
1043 | static int __kprobes try_to_disable_aggr_kprobe(struct kprobe *p) |
1044 | { |
1045 | struct kprobe *kp; |
1046 | |
1047 | list_for_each_entry_rcu(kp, &p->list, list) { |
1048 | if (!kprobe_disabled(kp)) |
1049 | /* |
1050 | * There is an active probe on the list. |
1051 | * We can't disable aggr_kprobe. |
1052 | */ |
1053 | return 0; |
1054 | } |
1055 | p->flags |= KPROBE_FLAG_DISABLED; |
1056 | return 1; |
1057 | } |
1058 | |
1059 | static int __kprobes in_kprobes_functions(unsigned long addr) |
1060 | { |
1061 | struct kprobe_blackpoint *kb; |
1062 | |
1063 | if (addr >= (unsigned long)__kprobes_text_start && |
1064 | addr < (unsigned long)__kprobes_text_end) |
1065 | return -EINVAL; |
1066 | /* |
1067 | * If there exists a kprobe_blacklist, verify and |
1068 | * fail any probe registration in the prohibited area |
1069 | */ |
1070 | for (kb = kprobe_blacklist; kb->name != NULL; kb++) { |
1071 | if (kb->start_addr) { |
1072 | if (addr >= kb->start_addr && |
1073 | addr < (kb->start_addr + kb->range)) |
1074 | return -EINVAL; |
1075 | } |
1076 | } |
1077 | return 0; |
1078 | } |
1079 | |
1080 | /* |
1081 | * If we have a symbol_name argument, look it up and add the offset field |
1082 | * to it. This way, we can specify a relative address to a symbol. |
1083 | */ |
1084 | static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p) |
1085 | { |
1086 | kprobe_opcode_t *addr = p->addr; |
1087 | if (p->symbol_name) { |
1088 | if (addr) |
1089 | return NULL; |
1090 | kprobe_lookup_name(p->symbol_name, addr); |
1091 | } |
1092 | |
1093 | if (!addr) |
1094 | return NULL; |
1095 | return (kprobe_opcode_t *)(((char *)addr) + p->offset); |
1096 | } |
1097 | |
1098 | /* Check passed kprobe is valid and return kprobe in kprobe_table. */ |
1099 | static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p) |
1100 | { |
1101 | struct kprobe *old_p, *list_p; |
1102 | |
1103 | old_p = get_kprobe(p->addr); |
1104 | if (unlikely(!old_p)) |
1105 | return NULL; |
1106 | |
1107 | if (p != old_p) { |
1108 | list_for_each_entry_rcu(list_p, &old_p->list, list) |
1109 | if (list_p == p) |
1110 | /* kprobe p is a valid probe */ |
1111 | goto valid; |
1112 | return NULL; |
1113 | } |
1114 | valid: |
1115 | return old_p; |
1116 | } |
1117 | |
1118 | /* Return error if the kprobe is being re-registered */ |
1119 | static inline int check_kprobe_rereg(struct kprobe *p) |
1120 | { |
1121 | int ret = 0; |
1122 | struct kprobe *old_p; |
1123 | |
1124 | mutex_lock(&kprobe_mutex); |
1125 | old_p = __get_valid_kprobe(p); |
1126 | if (old_p) |
1127 | ret = -EINVAL; |
1128 | mutex_unlock(&kprobe_mutex); |
1129 | return ret; |
1130 | } |
1131 | |
1132 | int __kprobes register_kprobe(struct kprobe *p) |
1133 | { |
1134 | int ret = 0; |
1135 | struct kprobe *old_p; |
1136 | struct module *probed_mod; |
1137 | kprobe_opcode_t *addr; |
1138 | |
1139 | addr = kprobe_addr(p); |
1140 | if (!addr) |
1141 | return -EINVAL; |
1142 | p->addr = addr; |
1143 | |
1144 | ret = check_kprobe_rereg(p); |
1145 | if (ret) |
1146 | return ret; |
1147 | |
1148 | jump_label_lock(); |
1149 | preempt_disable(); |
1150 | if (!kernel_text_address((unsigned long) p->addr) || |
1151 | in_kprobes_functions((unsigned long) p->addr) || |
1152 | ftrace_text_reserved(p->addr, p->addr) || |
1153 | jump_label_text_reserved(p->addr, p->addr)) |
1154 | goto fail_with_jump_label; |
1155 | |
1156 | /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */ |
1157 | p->flags &= KPROBE_FLAG_DISABLED; |
1158 | |
1159 | /* |
1160 | * Check if are we probing a module. |
1161 | */ |
1162 | probed_mod = __module_text_address((unsigned long) p->addr); |
1163 | if (probed_mod) { |
1164 | /* |
1165 | * We must hold a refcount of the probed module while updating |
1166 | * its code to prohibit unexpected unloading. |
1167 | */ |
1168 | if (unlikely(!try_module_get(probed_mod))) |
1169 | goto fail_with_jump_label; |
1170 | |
1171 | /* |
1172 | * If the module freed .init.text, we couldn't insert |
1173 | * kprobes in there. |
1174 | */ |
1175 | if (within_module_init((unsigned long)p->addr, probed_mod) && |
1176 | probed_mod->state != MODULE_STATE_COMING) { |
1177 | module_put(probed_mod); |
1178 | goto fail_with_jump_label; |
1179 | } |
1180 | } |
1181 | preempt_enable(); |
1182 | jump_label_unlock(); |
1183 | |
1184 | p->nmissed = 0; |
1185 | INIT_LIST_HEAD(&p->list); |
1186 | mutex_lock(&kprobe_mutex); |
1187 | |
1188 | jump_label_lock(); /* needed to call jump_label_text_reserved() */ |
1189 | |
1190 | get_online_cpus(); /* For avoiding text_mutex deadlock. */ |
1191 | mutex_lock(&text_mutex); |
1192 | |
1193 | old_p = get_kprobe(p->addr); |
1194 | if (old_p) { |
1195 | /* Since this may unoptimize old_p, locking text_mutex. */ |
1196 | ret = register_aggr_kprobe(old_p, p); |
1197 | goto out; |
1198 | } |
1199 | |
1200 | ret = arch_prepare_kprobe(p); |
1201 | if (ret) |
1202 | goto out; |
1203 | |
1204 | INIT_HLIST_NODE(&p->hlist); |
1205 | hlist_add_head_rcu(&p->hlist, |
1206 | &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]); |
1207 | |
1208 | if (!kprobes_all_disarmed && !kprobe_disabled(p)) |
1209 | __arm_kprobe(p); |
1210 | |
1211 | /* Try to optimize kprobe */ |
1212 | try_to_optimize_kprobe(p); |
1213 | |
1214 | out: |
1215 | mutex_unlock(&text_mutex); |
1216 | put_online_cpus(); |
1217 | jump_label_unlock(); |
1218 | mutex_unlock(&kprobe_mutex); |
1219 | |
1220 | if (probed_mod) |
1221 | module_put(probed_mod); |
1222 | |
1223 | return ret; |
1224 | |
1225 | fail_with_jump_label: |
1226 | preempt_enable(); |
1227 | jump_label_unlock(); |
1228 | return -EINVAL; |
1229 | } |
1230 | EXPORT_SYMBOL_GPL(register_kprobe); |
1231 | |
1232 | /* |
1233 | * Unregister a kprobe without a scheduler synchronization. |
1234 | */ |
1235 | static int __kprobes __unregister_kprobe_top(struct kprobe *p) |
1236 | { |
1237 | struct kprobe *old_p, *list_p; |
1238 | |
1239 | old_p = __get_valid_kprobe(p); |
1240 | if (old_p == NULL) |
1241 | return -EINVAL; |
1242 | |
1243 | if (old_p == p || |
1244 | (kprobe_aggrprobe(old_p) && |
1245 | list_is_singular(&old_p->list))) { |
1246 | /* |
1247 | * Only probe on the hash list. Disarm only if kprobes are |
1248 | * enabled and not gone - otherwise, the breakpoint would |
1249 | * already have been removed. We save on flushing icache. |
1250 | */ |
1251 | if (!kprobes_all_disarmed && !kprobe_disabled(old_p)) |
1252 | disarm_kprobe(old_p); |
1253 | hlist_del_rcu(&old_p->hlist); |
1254 | } else { |
1255 | if (p->break_handler && !kprobe_gone(p)) |
1256 | old_p->break_handler = NULL; |
1257 | if (p->post_handler && !kprobe_gone(p)) { |
1258 | list_for_each_entry_rcu(list_p, &old_p->list, list) { |
1259 | if ((list_p != p) && (list_p->post_handler)) |
1260 | goto noclean; |
1261 | } |
1262 | old_p->post_handler = NULL; |
1263 | } |
1264 | noclean: |
1265 | list_del_rcu(&p->list); |
1266 | if (!kprobe_disabled(old_p)) { |
1267 | try_to_disable_aggr_kprobe(old_p); |
1268 | if (!kprobes_all_disarmed) { |
1269 | if (kprobe_disabled(old_p)) |
1270 | disarm_kprobe(old_p); |
1271 | else |
1272 | /* Try to optimize this probe again */ |
1273 | optimize_kprobe(old_p); |
1274 | } |
1275 | } |
1276 | } |
1277 | return 0; |
1278 | } |
1279 | |
1280 | static void __kprobes __unregister_kprobe_bottom(struct kprobe *p) |
1281 | { |
1282 | struct kprobe *old_p; |
1283 | |
1284 | if (list_empty(&p->list)) |
1285 | arch_remove_kprobe(p); |
1286 | else if (list_is_singular(&p->list)) { |
1287 | /* "p" is the last child of an aggr_kprobe */ |
1288 | old_p = list_entry(p->list.next, struct kprobe, list); |
1289 | list_del(&p->list); |
1290 | arch_remove_kprobe(old_p); |
1291 | free_aggr_kprobe(old_p); |
1292 | } |
1293 | } |
1294 | |
1295 | int __kprobes register_kprobes(struct kprobe **kps, int num) |
1296 | { |
1297 | int i, ret = 0; |
1298 | |
1299 | if (num <= 0) |
1300 | return -EINVAL; |
1301 | for (i = 0; i < num; i++) { |
1302 | ret = register_kprobe(kps[i]); |
1303 | if (ret < 0) { |
1304 | if (i > 0) |
1305 | unregister_kprobes(kps, i); |
1306 | break; |
1307 | } |
1308 | } |
1309 | return ret; |
1310 | } |
1311 | EXPORT_SYMBOL_GPL(register_kprobes); |
1312 | |
1313 | void __kprobes unregister_kprobe(struct kprobe *p) |
1314 | { |
1315 | unregister_kprobes(&p, 1); |
1316 | } |
1317 | EXPORT_SYMBOL_GPL(unregister_kprobe); |
1318 | |
1319 | void __kprobes unregister_kprobes(struct kprobe **kps, int num) |
1320 | { |
1321 | int i; |
1322 | |
1323 | if (num <= 0) |
1324 | return; |
1325 | mutex_lock(&kprobe_mutex); |
1326 | for (i = 0; i < num; i++) |
1327 | if (__unregister_kprobe_top(kps[i]) < 0) |
1328 | kps[i]->addr = NULL; |
1329 | mutex_unlock(&kprobe_mutex); |
1330 | |
1331 | synchronize_sched(); |
1332 | for (i = 0; i < num; i++) |
1333 | if (kps[i]->addr) |
1334 | __unregister_kprobe_bottom(kps[i]); |
1335 | } |
1336 | EXPORT_SYMBOL_GPL(unregister_kprobes); |
1337 | |
1338 | static struct notifier_block kprobe_exceptions_nb = { |
1339 | .notifier_call = kprobe_exceptions_notify, |
1340 | .priority = 0x7fffffff /* we need to be notified first */ |
1341 | }; |
1342 | |
1343 | unsigned long __weak arch_deref_entry_point(void *entry) |
1344 | { |
1345 | return (unsigned long)entry; |
1346 | } |
1347 | |
1348 | int __kprobes register_jprobes(struct jprobe **jps, int num) |
1349 | { |
1350 | struct jprobe *jp; |
1351 | int ret = 0, i; |
1352 | |
1353 | if (num <= 0) |
1354 | return -EINVAL; |
1355 | for (i = 0; i < num; i++) { |
1356 | unsigned long addr, offset; |
1357 | jp = jps[i]; |
1358 | addr = arch_deref_entry_point(jp->entry); |
1359 | |
1360 | /* Verify probepoint is a function entry point */ |
1361 | if (kallsyms_lookup_size_offset(addr, NULL, &offset) && |
1362 | offset == 0) { |
1363 | jp->kp.pre_handler = setjmp_pre_handler; |
1364 | jp->kp.break_handler = longjmp_break_handler; |
1365 | ret = register_kprobe(&jp->kp); |
1366 | } else |
1367 | ret = -EINVAL; |
1368 | |
1369 | if (ret < 0) { |
1370 | if (i > 0) |
1371 | unregister_jprobes(jps, i); |
1372 | break; |
1373 | } |
1374 | } |
1375 | return ret; |
1376 | } |
1377 | EXPORT_SYMBOL_GPL(register_jprobes); |
1378 | |
1379 | int __kprobes register_jprobe(struct jprobe *jp) |
1380 | { |
1381 | return register_jprobes(&jp, 1); |
1382 | } |
1383 | EXPORT_SYMBOL_GPL(register_jprobe); |
1384 | |
1385 | void __kprobes unregister_jprobe(struct jprobe *jp) |
1386 | { |
1387 | unregister_jprobes(&jp, 1); |
1388 | } |
1389 | EXPORT_SYMBOL_GPL(unregister_jprobe); |
1390 | |
1391 | void __kprobes unregister_jprobes(struct jprobe **jps, int num) |
1392 | { |
1393 | int i; |
1394 | |
1395 | if (num <= 0) |
1396 | return; |
1397 | mutex_lock(&kprobe_mutex); |
1398 | for (i = 0; i < num; i++) |
1399 | if (__unregister_kprobe_top(&jps[i]->kp) < 0) |
1400 | jps[i]->kp.addr = NULL; |
1401 | mutex_unlock(&kprobe_mutex); |
1402 | |
1403 | synchronize_sched(); |
1404 | for (i = 0; i < num; i++) { |
1405 | if (jps[i]->kp.addr) |
1406 | __unregister_kprobe_bottom(&jps[i]->kp); |
1407 | } |
1408 | } |
1409 | EXPORT_SYMBOL_GPL(unregister_jprobes); |
1410 | |
1411 | #ifdef CONFIG_KRETPROBES |
1412 | /* |
1413 | * This kprobe pre_handler is registered with every kretprobe. When probe |
1414 | * hits it will set up the return probe. |
1415 | */ |
1416 | static int __kprobes pre_handler_kretprobe(struct kprobe *p, |
1417 | struct pt_regs *regs) |
1418 | { |
1419 | struct kretprobe *rp = container_of(p, struct kretprobe, kp); |
1420 | unsigned long hash, flags = 0; |
1421 | struct kretprobe_instance *ri; |
1422 | |
1423 | /*TODO: consider to only swap the RA after the last pre_handler fired */ |
1424 | hash = hash_ptr(current, KPROBE_HASH_BITS); |
1425 | spin_lock_irqsave(&rp->lock, flags); |
1426 | if (!hlist_empty(&rp->free_instances)) { |
1427 | ri = hlist_entry(rp->free_instances.first, |
1428 | struct kretprobe_instance, hlist); |
1429 | hlist_del(&ri->hlist); |
1430 | spin_unlock_irqrestore(&rp->lock, flags); |
1431 | |
1432 | ri->rp = rp; |
1433 | ri->task = current; |
1434 | |
1435 | if (rp->entry_handler && rp->entry_handler(ri, regs)) |
1436 | return 0; |
1437 | |
1438 | arch_prepare_kretprobe(ri, regs); |
1439 | |
1440 | /* XXX(hch): why is there no hlist_move_head? */ |
1441 | INIT_HLIST_NODE(&ri->hlist); |
1442 | kretprobe_table_lock(hash, &flags); |
1443 | hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]); |
1444 | kretprobe_table_unlock(hash, &flags); |
1445 | } else { |
1446 | rp->nmissed++; |
1447 | spin_unlock_irqrestore(&rp->lock, flags); |
1448 | } |
1449 | return 0; |
1450 | } |
1451 | |
1452 | int __kprobes register_kretprobe(struct kretprobe *rp) |
1453 | { |
1454 | int ret = 0; |
1455 | struct kretprobe_instance *inst; |
1456 | int i; |
1457 | void *addr; |
1458 | |
1459 | if (kretprobe_blacklist_size) { |
1460 | addr = kprobe_addr(&rp->kp); |
1461 | if (!addr) |
1462 | return -EINVAL; |
1463 | |
1464 | for (i = 0; kretprobe_blacklist[i].name != NULL; i++) { |
1465 | if (kretprobe_blacklist[i].addr == addr) |
1466 | return -EINVAL; |
1467 | } |
1468 | } |
1469 | |
1470 | rp->kp.pre_handler = pre_handler_kretprobe; |
1471 | rp->kp.post_handler = NULL; |
1472 | rp->kp.fault_handler = NULL; |
1473 | rp->kp.break_handler = NULL; |
1474 | |
1475 | /* Pre-allocate memory for max kretprobe instances */ |
1476 | if (rp->maxactive <= 0) { |
1477 | #ifdef CONFIG_PREEMPT |
1478 | rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus()); |
1479 | #else |
1480 | rp->maxactive = num_possible_cpus(); |
1481 | #endif |
1482 | } |
1483 | spin_lock_init(&rp->lock); |
1484 | INIT_HLIST_HEAD(&rp->free_instances); |
1485 | for (i = 0; i < rp->maxactive; i++) { |
1486 | inst = kmalloc(sizeof(struct kretprobe_instance) + |
1487 | rp->data_size, GFP_KERNEL); |
1488 | if (inst == NULL) { |
1489 | free_rp_inst(rp); |
1490 | return -ENOMEM; |
1491 | } |
1492 | INIT_HLIST_NODE(&inst->hlist); |
1493 | hlist_add_head(&inst->hlist, &rp->free_instances); |
1494 | } |
1495 | |
1496 | rp->nmissed = 0; |
1497 | /* Establish function entry probe point */ |
1498 | ret = register_kprobe(&rp->kp); |
1499 | if (ret != 0) |
1500 | free_rp_inst(rp); |
1501 | return ret; |
1502 | } |
1503 | EXPORT_SYMBOL_GPL(register_kretprobe); |
1504 | |
1505 | int __kprobes register_kretprobes(struct kretprobe **rps, int num) |
1506 | { |
1507 | int ret = 0, i; |
1508 | |
1509 | if (num <= 0) |
1510 | return -EINVAL; |
1511 | for (i = 0; i < num; i++) { |
1512 | ret = register_kretprobe(rps[i]); |
1513 | if (ret < 0) { |
1514 | if (i > 0) |
1515 | unregister_kretprobes(rps, i); |
1516 | break; |
1517 | } |
1518 | } |
1519 | return ret; |
1520 | } |
1521 | EXPORT_SYMBOL_GPL(register_kretprobes); |
1522 | |
1523 | void __kprobes unregister_kretprobe(struct kretprobe *rp) |
1524 | { |
1525 | unregister_kretprobes(&rp, 1); |
1526 | } |
1527 | EXPORT_SYMBOL_GPL(unregister_kretprobe); |
1528 | |
1529 | void __kprobes unregister_kretprobes(struct kretprobe **rps, int num) |
1530 | { |
1531 | int i; |
1532 | |
1533 | if (num <= 0) |
1534 | return; |
1535 | mutex_lock(&kprobe_mutex); |
1536 | for (i = 0; i < num; i++) |
1537 | if (__unregister_kprobe_top(&rps[i]->kp) < 0) |
1538 | rps[i]->kp.addr = NULL; |
1539 | mutex_unlock(&kprobe_mutex); |
1540 | |
1541 | synchronize_sched(); |
1542 | for (i = 0; i < num; i++) { |
1543 | if (rps[i]->kp.addr) { |
1544 | __unregister_kprobe_bottom(&rps[i]->kp); |
1545 | cleanup_rp_inst(rps[i]); |
1546 | } |
1547 | } |
1548 | } |
1549 | EXPORT_SYMBOL_GPL(unregister_kretprobes); |
1550 | |
1551 | #else /* CONFIG_KRETPROBES */ |
1552 | int __kprobes register_kretprobe(struct kretprobe *rp) |
1553 | { |
1554 | return -ENOSYS; |
1555 | } |
1556 | EXPORT_SYMBOL_GPL(register_kretprobe); |
1557 | |
1558 | int __kprobes register_kretprobes(struct kretprobe **rps, int num) |
1559 | { |
1560 | return -ENOSYS; |
1561 | } |
1562 | EXPORT_SYMBOL_GPL(register_kretprobes); |
1563 | |
1564 | void __kprobes unregister_kretprobe(struct kretprobe *rp) |
1565 | { |
1566 | } |
1567 | EXPORT_SYMBOL_GPL(unregister_kretprobe); |
1568 | |
1569 | void __kprobes unregister_kretprobes(struct kretprobe **rps, int num) |
1570 | { |
1571 | } |
1572 | EXPORT_SYMBOL_GPL(unregister_kretprobes); |
1573 | |
1574 | static int __kprobes pre_handler_kretprobe(struct kprobe *p, |
1575 | struct pt_regs *regs) |
1576 | { |
1577 | return 0; |
1578 | } |
1579 | |
1580 | #endif /* CONFIG_KRETPROBES */ |
1581 | |
1582 | /* Set the kprobe gone and remove its instruction buffer. */ |
1583 | static void __kprobes kill_kprobe(struct kprobe *p) |
1584 | { |
1585 | struct kprobe *kp; |
1586 | |
1587 | p->flags |= KPROBE_FLAG_GONE; |
1588 | if (kprobe_aggrprobe(p)) { |
1589 | /* |
1590 | * If this is an aggr_kprobe, we have to list all the |
1591 | * chained probes and mark them GONE. |
1592 | */ |
1593 | list_for_each_entry_rcu(kp, &p->list, list) |
1594 | kp->flags |= KPROBE_FLAG_GONE; |
1595 | p->post_handler = NULL; |
1596 | p->break_handler = NULL; |
1597 | kill_optimized_kprobe(p); |
1598 | } |
1599 | /* |
1600 | * Here, we can remove insn_slot safely, because no thread calls |
1601 | * the original probed function (which will be freed soon) any more. |
1602 | */ |
1603 | arch_remove_kprobe(p); |
1604 | } |
1605 | |
1606 | /* Disable one kprobe */ |
1607 | int __kprobes disable_kprobe(struct kprobe *kp) |
1608 | { |
1609 | int ret = 0; |
1610 | struct kprobe *p; |
1611 | |
1612 | mutex_lock(&kprobe_mutex); |
1613 | |
1614 | /* Check whether specified probe is valid. */ |
1615 | p = __get_valid_kprobe(kp); |
1616 | if (unlikely(p == NULL)) { |
1617 | ret = -EINVAL; |
1618 | goto out; |
1619 | } |
1620 | |
1621 | /* If the probe is already disabled (or gone), just return */ |
1622 | if (kprobe_disabled(kp)) |
1623 | goto out; |
1624 | |
1625 | kp->flags |= KPROBE_FLAG_DISABLED; |
1626 | if (p != kp) |
1627 | /* When kp != p, p is always enabled. */ |
1628 | try_to_disable_aggr_kprobe(p); |
1629 | |
1630 | if (!kprobes_all_disarmed && kprobe_disabled(p)) |
1631 | disarm_kprobe(p); |
1632 | out: |
1633 | mutex_unlock(&kprobe_mutex); |
1634 | return ret; |
1635 | } |
1636 | EXPORT_SYMBOL_GPL(disable_kprobe); |
1637 | |
1638 | /* Enable one kprobe */ |
1639 | int __kprobes enable_kprobe(struct kprobe *kp) |
1640 | { |
1641 | int ret = 0; |
1642 | struct kprobe *p; |
1643 | |
1644 | mutex_lock(&kprobe_mutex); |
1645 | |
1646 | /* Check whether specified probe is valid. */ |
1647 | p = __get_valid_kprobe(kp); |
1648 | if (unlikely(p == NULL)) { |
1649 | ret = -EINVAL; |
1650 | goto out; |
1651 | } |
1652 | |
1653 | if (kprobe_gone(kp)) { |
1654 | /* This kprobe has gone, we couldn't enable it. */ |
1655 | ret = -EINVAL; |
1656 | goto out; |
1657 | } |
1658 | |
1659 | if (p != kp) |
1660 | kp->flags &= ~KPROBE_FLAG_DISABLED; |
1661 | |
1662 | if (!kprobes_all_disarmed && kprobe_disabled(p)) { |
1663 | p->flags &= ~KPROBE_FLAG_DISABLED; |
1664 | arm_kprobe(p); |
1665 | } |
1666 | out: |
1667 | mutex_unlock(&kprobe_mutex); |
1668 | return ret; |
1669 | } |
1670 | EXPORT_SYMBOL_GPL(enable_kprobe); |
1671 | |
1672 | void __kprobes dump_kprobe(struct kprobe *kp) |
1673 | { |
1674 | printk(KERN_WARNING "Dumping kprobe:\n"); |
1675 | printk(KERN_WARNING "Name: %s\nAddress: %p\nOffset: %x\n", |
1676 | kp->symbol_name, kp->addr, kp->offset); |
1677 | } |
1678 | |
1679 | /* Module notifier call back, checking kprobes on the module */ |
1680 | static int __kprobes kprobes_module_callback(struct notifier_block *nb, |
1681 | unsigned long val, void *data) |
1682 | { |
1683 | struct module *mod = data; |
1684 | struct hlist_head *head; |
1685 | struct hlist_node *node; |
1686 | struct kprobe *p; |
1687 | unsigned int i; |
1688 | int checkcore = (val == MODULE_STATE_GOING); |
1689 | |
1690 | if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE) |
1691 | return NOTIFY_DONE; |
1692 | |
1693 | /* |
1694 | * When MODULE_STATE_GOING was notified, both of module .text and |
1695 | * .init.text sections would be freed. When MODULE_STATE_LIVE was |
1696 | * notified, only .init.text section would be freed. We need to |
1697 | * disable kprobes which have been inserted in the sections. |
1698 | */ |
1699 | mutex_lock(&kprobe_mutex); |
1700 | for (i = 0; i < KPROBE_TABLE_SIZE; i++) { |
1701 | head = &kprobe_table[i]; |
1702 | hlist_for_each_entry_rcu(p, node, head, hlist) |
1703 | if (within_module_init((unsigned long)p->addr, mod) || |
1704 | (checkcore && |
1705 | within_module_core((unsigned long)p->addr, mod))) { |
1706 | /* |
1707 | * The vaddr this probe is installed will soon |
1708 | * be vfreed buy not synced to disk. Hence, |
1709 | * disarming the breakpoint isn't needed. |
1710 | */ |
1711 | kill_kprobe(p); |
1712 | } |
1713 | } |
1714 | mutex_unlock(&kprobe_mutex); |
1715 | return NOTIFY_DONE; |
1716 | } |
1717 | |
1718 | static struct notifier_block kprobe_module_nb = { |
1719 | .notifier_call = kprobes_module_callback, |
1720 | .priority = 0 |
1721 | }; |
1722 | |
1723 | static int __init init_kprobes(void) |
1724 | { |
1725 | int i, err = 0; |
1726 | unsigned long offset = 0, size = 0; |
1727 | char *modname, namebuf[128]; |
1728 | const char *symbol_name; |
1729 | void *addr; |
1730 | struct kprobe_blackpoint *kb; |
1731 | |
1732 | /* FIXME allocate the probe table, currently defined statically */ |
1733 | /* initialize all list heads */ |
1734 | for (i = 0; i < KPROBE_TABLE_SIZE; i++) { |
1735 | INIT_HLIST_HEAD(&kprobe_table[i]); |
1736 | INIT_HLIST_HEAD(&kretprobe_inst_table[i]); |
1737 | spin_lock_init(&(kretprobe_table_locks[i].lock)); |
1738 | } |
1739 | |
1740 | /* |
1741 | * Lookup and populate the kprobe_blacklist. |
1742 | * |
1743 | * Unlike the kretprobe blacklist, we'll need to determine |
1744 | * the range of addresses that belong to the said functions, |
1745 | * since a kprobe need not necessarily be at the beginning |
1746 | * of a function. |
1747 | */ |
1748 | for (kb = kprobe_blacklist; kb->name != NULL; kb++) { |
1749 | kprobe_lookup_name(kb->name, addr); |
1750 | if (!addr) |
1751 | continue; |
1752 | |
1753 | kb->start_addr = (unsigned long)addr; |
1754 | symbol_name = kallsyms_lookup(kb->start_addr, |
1755 | &size, &offset, &modname, namebuf); |
1756 | if (!symbol_name) |
1757 | kb->range = 0; |
1758 | else |
1759 | kb->range = size; |
1760 | } |
1761 | |
1762 | if (kretprobe_blacklist_size) { |
1763 | /* lookup the function address from its name */ |
1764 | for (i = 0; kretprobe_blacklist[i].name != NULL; i++) { |
1765 | kprobe_lookup_name(kretprobe_blacklist[i].name, |
1766 | kretprobe_blacklist[i].addr); |
1767 | if (!kretprobe_blacklist[i].addr) |
1768 | printk("kretprobe: lookup failed: %s\n", |
1769 | kretprobe_blacklist[i].name); |
1770 | } |
1771 | } |
1772 | |
1773 | #if defined(CONFIG_OPTPROBES) |
1774 | #if defined(__ARCH_WANT_KPROBES_INSN_SLOT) |
1775 | /* Init kprobe_optinsn_slots */ |
1776 | kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE; |
1777 | #endif |
1778 | /* By default, kprobes can be optimized */ |
1779 | kprobes_allow_optimization = true; |
1780 | #endif |
1781 | |
1782 | /* By default, kprobes are armed */ |
1783 | kprobes_all_disarmed = false; |
1784 | |
1785 | err = arch_init_kprobes(); |
1786 | if (!err) |
1787 | err = register_die_notifier(&kprobe_exceptions_nb); |
1788 | if (!err) |
1789 | err = register_module_notifier(&kprobe_module_nb); |
1790 | |
1791 | kprobes_initialized = (err == 0); |
1792 | |
1793 | if (!err) |
1794 | init_test_probes(); |
1795 | return err; |
1796 | } |
1797 | |
1798 | #ifdef CONFIG_DEBUG_FS |
1799 | static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p, |
1800 | const char *sym, int offset, char *modname, struct kprobe *pp) |
1801 | { |
1802 | char *kprobe_type; |
1803 | |
1804 | if (p->pre_handler == pre_handler_kretprobe) |
1805 | kprobe_type = "r"; |
1806 | else if (p->pre_handler == setjmp_pre_handler) |
1807 | kprobe_type = "j"; |
1808 | else |
1809 | kprobe_type = "k"; |
1810 | |
1811 | if (sym) |
1812 | seq_printf(pi, "%p %s %s+0x%x %s ", |
1813 | p->addr, kprobe_type, sym, offset, |
1814 | (modname ? modname : " ")); |
1815 | else |
1816 | seq_printf(pi, "%p %s %p ", |
1817 | p->addr, kprobe_type, p->addr); |
1818 | |
1819 | if (!pp) |
1820 | pp = p; |
1821 | seq_printf(pi, "%s%s%s\n", |
1822 | (kprobe_gone(p) ? "[GONE]" : ""), |
1823 | ((kprobe_disabled(p) && !kprobe_gone(p)) ? "[DISABLED]" : ""), |
1824 | (kprobe_optimized(pp) ? "[OPTIMIZED]" : "")); |
1825 | } |
1826 | |
1827 | static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos) |
1828 | { |
1829 | return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL; |
1830 | } |
1831 | |
1832 | static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos) |
1833 | { |
1834 | (*pos)++; |
1835 | if (*pos >= KPROBE_TABLE_SIZE) |
1836 | return NULL; |
1837 | return pos; |
1838 | } |
1839 | |
1840 | static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v) |
1841 | { |
1842 | /* Nothing to do */ |
1843 | } |
1844 | |
1845 | static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v) |
1846 | { |
1847 | struct hlist_head *head; |
1848 | struct hlist_node *node; |
1849 | struct kprobe *p, *kp; |
1850 | const char *sym = NULL; |
1851 | unsigned int i = *(loff_t *) v; |
1852 | unsigned long offset = 0; |
1853 | char *modname, namebuf[128]; |
1854 | |
1855 | head = &kprobe_table[i]; |
1856 | preempt_disable(); |
1857 | hlist_for_each_entry_rcu(p, node, head, hlist) { |
1858 | sym = kallsyms_lookup((unsigned long)p->addr, NULL, |
1859 | &offset, &modname, namebuf); |
1860 | if (kprobe_aggrprobe(p)) { |
1861 | list_for_each_entry_rcu(kp, &p->list, list) |
1862 | report_probe(pi, kp, sym, offset, modname, p); |
1863 | } else |
1864 | report_probe(pi, p, sym, offset, modname, NULL); |
1865 | } |
1866 | preempt_enable(); |
1867 | return 0; |
1868 | } |
1869 | |
1870 | static const struct seq_operations kprobes_seq_ops = { |
1871 | .start = kprobe_seq_start, |
1872 | .next = kprobe_seq_next, |
1873 | .stop = kprobe_seq_stop, |
1874 | .show = show_kprobe_addr |
1875 | }; |
1876 | |
1877 | static int __kprobes kprobes_open(struct inode *inode, struct file *filp) |
1878 | { |
1879 | return seq_open(filp, &kprobes_seq_ops); |
1880 | } |
1881 | |
1882 | static const struct file_operations debugfs_kprobes_operations = { |
1883 | .open = kprobes_open, |
1884 | .read = seq_read, |
1885 | .llseek = seq_lseek, |
1886 | .release = seq_release, |
1887 | }; |
1888 | |
1889 | static void __kprobes arm_all_kprobes(void) |
1890 | { |
1891 | struct hlist_head *head; |
1892 | struct hlist_node *node; |
1893 | struct kprobe *p; |
1894 | unsigned int i; |
1895 | |
1896 | mutex_lock(&kprobe_mutex); |
1897 | |
1898 | /* If kprobes are armed, just return */ |
1899 | if (!kprobes_all_disarmed) |
1900 | goto already_enabled; |
1901 | |
1902 | /* Arming kprobes doesn't optimize kprobe itself */ |
1903 | mutex_lock(&text_mutex); |
1904 | for (i = 0; i < KPROBE_TABLE_SIZE; i++) { |
1905 | head = &kprobe_table[i]; |
1906 | hlist_for_each_entry_rcu(p, node, head, hlist) |
1907 | if (!kprobe_disabled(p)) |
1908 | __arm_kprobe(p); |
1909 | } |
1910 | mutex_unlock(&text_mutex); |
1911 | |
1912 | kprobes_all_disarmed = false; |
1913 | printk(KERN_INFO "Kprobes globally enabled\n"); |
1914 | |
1915 | already_enabled: |
1916 | mutex_unlock(&kprobe_mutex); |
1917 | return; |
1918 | } |
1919 | |
1920 | static void __kprobes disarm_all_kprobes(void) |
1921 | { |
1922 | struct hlist_head *head; |
1923 | struct hlist_node *node; |
1924 | struct kprobe *p; |
1925 | unsigned int i; |
1926 | |
1927 | mutex_lock(&kprobe_mutex); |
1928 | |
1929 | /* If kprobes are already disarmed, just return */ |
1930 | if (kprobes_all_disarmed) |
1931 | goto already_disabled; |
1932 | |
1933 | kprobes_all_disarmed = true; |
1934 | printk(KERN_INFO "Kprobes globally disabled\n"); |
1935 | |
1936 | /* |
1937 | * Here we call get_online_cpus() for avoiding text_mutex deadlock, |
1938 | * because disarming may also unoptimize kprobes. |
1939 | */ |
1940 | get_online_cpus(); |
1941 | mutex_lock(&text_mutex); |
1942 | for (i = 0; i < KPROBE_TABLE_SIZE; i++) { |
1943 | head = &kprobe_table[i]; |
1944 | hlist_for_each_entry_rcu(p, node, head, hlist) { |
1945 | if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p)) |
1946 | __disarm_kprobe(p); |
1947 | } |
1948 | } |
1949 | |
1950 | mutex_unlock(&text_mutex); |
1951 | put_online_cpus(); |
1952 | mutex_unlock(&kprobe_mutex); |
1953 | /* Allow all currently running kprobes to complete */ |
1954 | synchronize_sched(); |
1955 | return; |
1956 | |
1957 | already_disabled: |
1958 | mutex_unlock(&kprobe_mutex); |
1959 | return; |
1960 | } |
1961 | |
1962 | /* |
1963 | * XXX: The debugfs bool file interface doesn't allow for callbacks |
1964 | * when the bool state is switched. We can reuse that facility when |
1965 | * available |
1966 | */ |
1967 | static ssize_t read_enabled_file_bool(struct file *file, |
1968 | char __user *user_buf, size_t count, loff_t *ppos) |
1969 | { |
1970 | char buf[3]; |
1971 | |
1972 | if (!kprobes_all_disarmed) |
1973 | buf[0] = '1'; |
1974 | else |
1975 | buf[0] = '0'; |
1976 | buf[1] = '\n'; |
1977 | buf[2] = 0x00; |
1978 | return simple_read_from_buffer(user_buf, count, ppos, buf, 2); |
1979 | } |
1980 | |
1981 | static ssize_t write_enabled_file_bool(struct file *file, |
1982 | const char __user *user_buf, size_t count, loff_t *ppos) |
1983 | { |
1984 | char buf[32]; |
1985 | int buf_size; |
1986 | |
1987 | buf_size = min(count, (sizeof(buf)-1)); |
1988 | if (copy_from_user(buf, user_buf, buf_size)) |
1989 | return -EFAULT; |
1990 | |
1991 | switch (buf[0]) { |
1992 | case 'y': |
1993 | case 'Y': |
1994 | case '1': |
1995 | arm_all_kprobes(); |
1996 | break; |
1997 | case 'n': |
1998 | case 'N': |
1999 | case '0': |
2000 | disarm_all_kprobes(); |
2001 | break; |
2002 | } |
2003 | |
2004 | return count; |
2005 | } |
2006 | |
2007 | static const struct file_operations fops_kp = { |
2008 | .read = read_enabled_file_bool, |
2009 | .write = write_enabled_file_bool, |
2010 | .llseek = default_llseek, |
2011 | }; |
2012 | |
2013 | static int __kprobes debugfs_kprobe_init(void) |
2014 | { |
2015 | struct dentry *dir, *file; |
2016 | unsigned int value = 1; |
2017 | |
2018 | dir = debugfs_create_dir("kprobes", NULL); |
2019 | if (!dir) |
2020 | return -ENOMEM; |
2021 | |
2022 | file = debugfs_create_file("list", 0444, dir, NULL, |
2023 | &debugfs_kprobes_operations); |
2024 | if (!file) { |
2025 | debugfs_remove(dir); |
2026 | return -ENOMEM; |
2027 | } |
2028 | |
2029 | file = debugfs_create_file("enabled", 0600, dir, |
2030 | &value, &fops_kp); |
2031 | if (!file) { |
2032 | debugfs_remove(dir); |
2033 | return -ENOMEM; |
2034 | } |
2035 | |
2036 | return 0; |
2037 | } |
2038 | |
2039 | late_initcall(debugfs_kprobe_init); |
2040 | #endif /* CONFIG_DEBUG_FS */ |
2041 | |
2042 | module_init(init_kprobes); |
2043 | |
2044 | /* defined in arch/.../kernel/kprobes.c */ |
2045 | EXPORT_SYMBOL_GPL(jprobe_return); |
2046 |
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