Commit | Line | Data |
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1da177e4 LT |
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. | |
b94cce92 HN |
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. | |
1da177e4 LT |
33 | */ |
34 | #include <linux/kprobes.h> | |
35 | #include <linux/spinlock.h> | |
36 | #include <linux/hash.h> | |
37 | #include <linux/init.h> | |
38 | #include <linux/module.h> | |
39 | #include <asm/cacheflush.h> | |
40 | #include <asm/errno.h> | |
41 | #include <asm/kdebug.h> | |
42 | ||
43 | #define KPROBE_HASH_BITS 6 | |
44 | #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS) | |
45 | ||
46 | static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; | |
b94cce92 | 47 | static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE]; |
1da177e4 LT |
48 | |
49 | unsigned int kprobe_cpu = NR_CPUS; | |
50 | static DEFINE_SPINLOCK(kprobe_lock); | |
64f562c6 | 51 | static struct kprobe *curr_kprobe; |
1da177e4 LT |
52 | |
53 | /* Locks kprobe: irqs must be disabled */ | |
54 | void lock_kprobes(void) | |
55 | { | |
56 | spin_lock(&kprobe_lock); | |
57 | kprobe_cpu = smp_processor_id(); | |
58 | } | |
59 | ||
60 | void unlock_kprobes(void) | |
61 | { | |
62 | kprobe_cpu = NR_CPUS; | |
63 | spin_unlock(&kprobe_lock); | |
64 | } | |
65 | ||
66 | /* You have to be holding the kprobe_lock */ | |
67 | struct kprobe *get_kprobe(void *addr) | |
68 | { | |
69 | struct hlist_head *head; | |
70 | struct hlist_node *node; | |
71 | ||
72 | head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)]; | |
73 | hlist_for_each(node, head) { | |
74 | struct kprobe *p = hlist_entry(node, struct kprobe, hlist); | |
75 | if (p->addr == addr) | |
76 | return p; | |
77 | } | |
78 | return NULL; | |
79 | } | |
80 | ||
64f562c6 AM |
81 | /* |
82 | * Aggregate handlers for multiple kprobes support - these handlers | |
83 | * take care of invoking the individual kprobe handlers on p->list | |
84 | */ | |
b94cce92 | 85 | static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs) |
64f562c6 AM |
86 | { |
87 | struct kprobe *kp; | |
88 | ||
89 | list_for_each_entry(kp, &p->list, list) { | |
90 | if (kp->pre_handler) { | |
91 | curr_kprobe = kp; | |
8b0914ea PP |
92 | if (kp->pre_handler(kp, regs)) |
93 | return 1; | |
64f562c6 | 94 | } |
8b0914ea | 95 | curr_kprobe = NULL; |
64f562c6 AM |
96 | } |
97 | return 0; | |
98 | } | |
99 | ||
b94cce92 HN |
100 | static void aggr_post_handler(struct kprobe *p, struct pt_regs *regs, |
101 | unsigned long flags) | |
64f562c6 AM |
102 | { |
103 | struct kprobe *kp; | |
104 | ||
105 | list_for_each_entry(kp, &p->list, list) { | |
106 | if (kp->post_handler) { | |
107 | curr_kprobe = kp; | |
108 | kp->post_handler(kp, regs, flags); | |
109 | curr_kprobe = NULL; | |
110 | } | |
111 | } | |
112 | return; | |
113 | } | |
114 | ||
b94cce92 HN |
115 | static int aggr_fault_handler(struct kprobe *p, struct pt_regs *regs, |
116 | int trapnr) | |
64f562c6 AM |
117 | { |
118 | /* | |
119 | * if we faulted "during" the execution of a user specified | |
120 | * probe handler, invoke just that probe's fault handler | |
121 | */ | |
122 | if (curr_kprobe && curr_kprobe->fault_handler) { | |
123 | if (curr_kprobe->fault_handler(curr_kprobe, regs, trapnr)) | |
124 | return 1; | |
125 | } | |
126 | return 0; | |
127 | } | |
128 | ||
8b0914ea PP |
129 | static int aggr_break_handler(struct kprobe *p, struct pt_regs *regs) |
130 | { | |
131 | struct kprobe *kp = curr_kprobe; | |
132 | if (curr_kprobe && kp->break_handler) { | |
133 | if (kp->break_handler(kp, regs)) { | |
134 | curr_kprobe = NULL; | |
135 | return 1; | |
136 | } | |
137 | } | |
138 | curr_kprobe = NULL; | |
139 | return 0; | |
140 | } | |
141 | ||
b94cce92 HN |
142 | struct kprobe trampoline_p = { |
143 | .addr = (kprobe_opcode_t *) &kretprobe_trampoline, | |
144 | .pre_handler = trampoline_probe_handler, | |
145 | .post_handler = trampoline_post_handler | |
146 | }; | |
147 | ||
148 | struct kretprobe_instance *get_free_rp_inst(struct kretprobe *rp) | |
149 | { | |
150 | struct hlist_node *node; | |
151 | struct kretprobe_instance *ri; | |
152 | hlist_for_each_entry(ri, node, &rp->free_instances, uflist) | |
153 | return ri; | |
154 | return NULL; | |
155 | } | |
156 | ||
157 | static struct kretprobe_instance *get_used_rp_inst(struct kretprobe *rp) | |
158 | { | |
159 | struct hlist_node *node; | |
160 | struct kretprobe_instance *ri; | |
161 | hlist_for_each_entry(ri, node, &rp->used_instances, uflist) | |
162 | return ri; | |
163 | return NULL; | |
164 | } | |
165 | ||
166 | struct kretprobe_instance *get_rp_inst(void *sara) | |
167 | { | |
168 | struct hlist_head *head; | |
169 | struct hlist_node *node; | |
170 | struct task_struct *tsk; | |
171 | struct kretprobe_instance *ri; | |
172 | ||
173 | tsk = arch_get_kprobe_task(sara); | |
174 | head = &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)]; | |
175 | hlist_for_each_entry(ri, node, head, hlist) { | |
176 | if (ri->stack_addr == sara) | |
177 | return ri; | |
178 | } | |
179 | return NULL; | |
180 | } | |
181 | ||
182 | void add_rp_inst(struct kretprobe_instance *ri) | |
183 | { | |
184 | struct task_struct *tsk; | |
185 | /* | |
186 | * Remove rp inst off the free list - | |
187 | * Add it back when probed function returns | |
188 | */ | |
189 | hlist_del(&ri->uflist); | |
190 | tsk = arch_get_kprobe_task(ri->stack_addr); | |
191 | /* Add rp inst onto table */ | |
192 | INIT_HLIST_NODE(&ri->hlist); | |
193 | hlist_add_head(&ri->hlist, | |
194 | &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)]); | |
195 | ||
196 | /* Also add this rp inst to the used list. */ | |
197 | INIT_HLIST_NODE(&ri->uflist); | |
198 | hlist_add_head(&ri->uflist, &ri->rp->used_instances); | |
199 | } | |
200 | ||
201 | void recycle_rp_inst(struct kretprobe_instance *ri) | |
202 | { | |
203 | /* remove rp inst off the rprobe_inst_table */ | |
204 | hlist_del(&ri->hlist); | |
205 | if (ri->rp) { | |
206 | /* remove rp inst off the used list */ | |
207 | hlist_del(&ri->uflist); | |
208 | /* put rp inst back onto the free list */ | |
209 | INIT_HLIST_NODE(&ri->uflist); | |
210 | hlist_add_head(&ri->uflist, &ri->rp->free_instances); | |
211 | } else | |
212 | /* Unregistering */ | |
213 | kfree(ri); | |
214 | } | |
215 | ||
216 | struct hlist_head * kretprobe_inst_table_head(struct task_struct *tsk) | |
217 | { | |
218 | return &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)]; | |
219 | } | |
220 | ||
221 | struct kretprobe_instance *get_rp_inst_tsk(struct task_struct *tk) | |
222 | { | |
223 | struct task_struct *tsk; | |
224 | struct hlist_head *head; | |
225 | struct hlist_node *node; | |
226 | struct kretprobe_instance *ri; | |
227 | ||
228 | head = &kretprobe_inst_table[hash_ptr(tk, KPROBE_HASH_BITS)]; | |
229 | ||
230 | hlist_for_each_entry(ri, node, head, hlist) { | |
231 | tsk = arch_get_kprobe_task(ri->stack_addr); | |
232 | if (tsk == tk) | |
233 | return ri; | |
234 | } | |
235 | return NULL; | |
236 | } | |
237 | ||
238 | /* | |
239 | * This function is called from do_exit or do_execv when task tk's stack is | |
240 | * about to be recycled. Recycle any function-return probe instances | |
241 | * associated with this task. These represent probed functions that have | |
242 | * been called but may never return. | |
243 | */ | |
244 | void kprobe_flush_task(struct task_struct *tk) | |
245 | { | |
0aa55e4d HN |
246 | unsigned long flags = 0; |
247 | spin_lock_irqsave(&kprobe_lock, flags); | |
248 | arch_kprobe_flush_task(tk); | |
249 | spin_unlock_irqrestore(&kprobe_lock, flags); | |
b94cce92 HN |
250 | } |
251 | ||
252 | /* | |
253 | * This kprobe pre_handler is registered with every kretprobe. When probe | |
254 | * hits it will set up the return probe. | |
255 | */ | |
256 | static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs) | |
257 | { | |
258 | struct kretprobe *rp = container_of(p, struct kretprobe, kp); | |
259 | ||
260 | /*TODO: consider to only swap the RA after the last pre_handler fired */ | |
261 | arch_prepare_kretprobe(rp, regs); | |
262 | return 0; | |
263 | } | |
264 | ||
265 | static inline void free_rp_inst(struct kretprobe *rp) | |
266 | { | |
267 | struct kretprobe_instance *ri; | |
268 | while ((ri = get_free_rp_inst(rp)) != NULL) { | |
269 | hlist_del(&ri->uflist); | |
270 | kfree(ri); | |
271 | } | |
272 | } | |
273 | ||
8b0914ea PP |
274 | /* |
275 | * Keep all fields in the kprobe consistent | |
276 | */ | |
277 | static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p) | |
278 | { | |
279 | memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t)); | |
280 | memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn)); | |
281 | } | |
282 | ||
283 | /* | |
284 | * Add the new probe to old_p->list. Fail if this is the | |
285 | * second jprobe at the address - two jprobes can't coexist | |
286 | */ | |
287 | static int add_new_kprobe(struct kprobe *old_p, struct kprobe *p) | |
288 | { | |
289 | struct kprobe *kp; | |
290 | ||
291 | if (p->break_handler) { | |
292 | list_for_each_entry(kp, &old_p->list, list) { | |
293 | if (kp->break_handler) | |
294 | return -EEXIST; | |
295 | } | |
296 | list_add_tail(&p->list, &old_p->list); | |
297 | } else | |
298 | list_add(&p->list, &old_p->list); | |
299 | return 0; | |
300 | } | |
301 | ||
64f562c6 AM |
302 | /* |
303 | * Fill in the required fields of the "manager kprobe". Replace the | |
304 | * earlier kprobe in the hlist with the manager kprobe | |
305 | */ | |
306 | static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p) | |
307 | { | |
8b0914ea | 308 | copy_kprobe(p, ap); |
64f562c6 | 309 | ap->addr = p->addr; |
64f562c6 AM |
310 | ap->pre_handler = aggr_pre_handler; |
311 | ap->post_handler = aggr_post_handler; | |
312 | ap->fault_handler = aggr_fault_handler; | |
8b0914ea | 313 | ap->break_handler = aggr_break_handler; |
64f562c6 AM |
314 | |
315 | INIT_LIST_HEAD(&ap->list); | |
316 | list_add(&p->list, &ap->list); | |
317 | ||
318 | INIT_HLIST_NODE(&ap->hlist); | |
319 | hlist_del(&p->hlist); | |
320 | hlist_add_head(&ap->hlist, | |
321 | &kprobe_table[hash_ptr(ap->addr, KPROBE_HASH_BITS)]); | |
322 | } | |
323 | ||
324 | /* | |
325 | * This is the second or subsequent kprobe at the address - handle | |
326 | * the intricacies | |
327 | * TODO: Move kcalloc outside the spinlock | |
328 | */ | |
329 | static int register_aggr_kprobe(struct kprobe *old_p, struct kprobe *p) | |
330 | { | |
331 | int ret = 0; | |
332 | struct kprobe *ap; | |
333 | ||
8b0914ea PP |
334 | if (old_p->pre_handler == aggr_pre_handler) { |
335 | copy_kprobe(old_p, p); | |
336 | ret = add_new_kprobe(old_p, p); | |
64f562c6 AM |
337 | } else { |
338 | ap = kcalloc(1, sizeof(struct kprobe), GFP_ATOMIC); | |
339 | if (!ap) | |
340 | return -ENOMEM; | |
341 | add_aggr_kprobe(ap, old_p); | |
8b0914ea PP |
342 | copy_kprobe(ap, p); |
343 | ret = add_new_kprobe(ap, p); | |
64f562c6 AM |
344 | } |
345 | return ret; | |
346 | } | |
347 | ||
348 | /* kprobe removal house-keeping routines */ | |
349 | static inline void cleanup_kprobe(struct kprobe *p, unsigned long flags) | |
350 | { | |
7e1048b1 | 351 | arch_disarm_kprobe(p); |
64f562c6 | 352 | hlist_del(&p->hlist); |
64f562c6 AM |
353 | spin_unlock_irqrestore(&kprobe_lock, flags); |
354 | arch_remove_kprobe(p); | |
355 | } | |
356 | ||
357 | static inline void cleanup_aggr_kprobe(struct kprobe *old_p, | |
358 | struct kprobe *p, unsigned long flags) | |
359 | { | |
360 | list_del(&p->list); | |
361 | if (list_empty(&old_p->list)) { | |
362 | cleanup_kprobe(old_p, flags); | |
363 | kfree(old_p); | |
364 | } else | |
365 | spin_unlock_irqrestore(&kprobe_lock, flags); | |
366 | } | |
367 | ||
1da177e4 LT |
368 | int register_kprobe(struct kprobe *p) |
369 | { | |
370 | int ret = 0; | |
371 | unsigned long flags = 0; | |
64f562c6 | 372 | struct kprobe *old_p; |
1da177e4 LT |
373 | |
374 | if ((ret = arch_prepare_kprobe(p)) != 0) { | |
375 | goto rm_kprobe; | |
376 | } | |
377 | spin_lock_irqsave(&kprobe_lock, flags); | |
64f562c6 | 378 | old_p = get_kprobe(p->addr); |
ea32c65c | 379 | p->nmissed = 0; |
64f562c6 AM |
380 | if (old_p) { |
381 | ret = register_aggr_kprobe(old_p, p); | |
1da177e4 LT |
382 | goto out; |
383 | } | |
1da177e4 | 384 | |
64f562c6 AM |
385 | arch_copy_kprobe(p); |
386 | INIT_HLIST_NODE(&p->hlist); | |
1da177e4 LT |
387 | hlist_add_head(&p->hlist, |
388 | &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]); | |
389 | ||
7e1048b1 RL |
390 | arch_arm_kprobe(p); |
391 | ||
1da177e4 LT |
392 | out: |
393 | spin_unlock_irqrestore(&kprobe_lock, flags); | |
394 | rm_kprobe: | |
395 | if (ret == -EEXIST) | |
396 | arch_remove_kprobe(p); | |
397 | return ret; | |
398 | } | |
399 | ||
400 | void unregister_kprobe(struct kprobe *p) | |
401 | { | |
402 | unsigned long flags; | |
64f562c6 AM |
403 | struct kprobe *old_p; |
404 | ||
1da177e4 | 405 | spin_lock_irqsave(&kprobe_lock, flags); |
64f562c6 AM |
406 | old_p = get_kprobe(p->addr); |
407 | if (old_p) { | |
408 | if (old_p->pre_handler == aggr_pre_handler) | |
409 | cleanup_aggr_kprobe(old_p, p, flags); | |
410 | else | |
411 | cleanup_kprobe(p, flags); | |
412 | } else | |
04dea5f9 | 413 | spin_unlock_irqrestore(&kprobe_lock, flags); |
1da177e4 LT |
414 | } |
415 | ||
416 | static struct notifier_block kprobe_exceptions_nb = { | |
417 | .notifier_call = kprobe_exceptions_notify, | |
418 | .priority = 0x7fffffff /* we need to notified first */ | |
419 | }; | |
420 | ||
421 | int register_jprobe(struct jprobe *jp) | |
422 | { | |
423 | /* Todo: Verify probepoint is a function entry point */ | |
424 | jp->kp.pre_handler = setjmp_pre_handler; | |
425 | jp->kp.break_handler = longjmp_break_handler; | |
426 | ||
427 | return register_kprobe(&jp->kp); | |
428 | } | |
429 | ||
430 | void unregister_jprobe(struct jprobe *jp) | |
431 | { | |
432 | unregister_kprobe(&jp->kp); | |
433 | } | |
434 | ||
b94cce92 HN |
435 | #ifdef ARCH_SUPPORTS_KRETPROBES |
436 | ||
437 | int register_kretprobe(struct kretprobe *rp) | |
438 | { | |
439 | int ret = 0; | |
440 | struct kretprobe_instance *inst; | |
441 | int i; | |
442 | ||
443 | rp->kp.pre_handler = pre_handler_kretprobe; | |
444 | ||
445 | /* Pre-allocate memory for max kretprobe instances */ | |
446 | if (rp->maxactive <= 0) { | |
447 | #ifdef CONFIG_PREEMPT | |
448 | rp->maxactive = max(10, 2 * NR_CPUS); | |
449 | #else | |
450 | rp->maxactive = NR_CPUS; | |
451 | #endif | |
452 | } | |
453 | INIT_HLIST_HEAD(&rp->used_instances); | |
454 | INIT_HLIST_HEAD(&rp->free_instances); | |
455 | for (i = 0; i < rp->maxactive; i++) { | |
456 | inst = kmalloc(sizeof(struct kretprobe_instance), GFP_KERNEL); | |
457 | if (inst == NULL) { | |
458 | free_rp_inst(rp); | |
459 | return -ENOMEM; | |
460 | } | |
461 | INIT_HLIST_NODE(&inst->uflist); | |
462 | hlist_add_head(&inst->uflist, &rp->free_instances); | |
463 | } | |
464 | ||
465 | rp->nmissed = 0; | |
466 | /* Establish function entry probe point */ | |
467 | if ((ret = register_kprobe(&rp->kp)) != 0) | |
468 | free_rp_inst(rp); | |
469 | return ret; | |
470 | } | |
471 | ||
472 | #else /* ARCH_SUPPORTS_KRETPROBES */ | |
473 | ||
474 | int register_kretprobe(struct kretprobe *rp) | |
475 | { | |
476 | return -ENOSYS; | |
477 | } | |
478 | ||
479 | #endif /* ARCH_SUPPORTS_KRETPROBES */ | |
480 | ||
481 | void unregister_kretprobe(struct kretprobe *rp) | |
482 | { | |
483 | unsigned long flags; | |
484 | struct kretprobe_instance *ri; | |
485 | ||
486 | unregister_kprobe(&rp->kp); | |
487 | /* No race here */ | |
488 | spin_lock_irqsave(&kprobe_lock, flags); | |
489 | free_rp_inst(rp); | |
490 | while ((ri = get_used_rp_inst(rp)) != NULL) { | |
491 | ri->rp = NULL; | |
492 | hlist_del(&ri->uflist); | |
493 | } | |
494 | spin_unlock_irqrestore(&kprobe_lock, flags); | |
495 | } | |
496 | ||
1da177e4 LT |
497 | static int __init init_kprobes(void) |
498 | { | |
499 | int i, err = 0; | |
500 | ||
501 | /* FIXME allocate the probe table, currently defined statically */ | |
502 | /* initialize all list heads */ | |
b94cce92 | 503 | for (i = 0; i < KPROBE_TABLE_SIZE; i++) { |
1da177e4 | 504 | INIT_HLIST_HEAD(&kprobe_table[i]); |
b94cce92 HN |
505 | INIT_HLIST_HEAD(&kretprobe_inst_table[i]); |
506 | } | |
1da177e4 LT |
507 | |
508 | err = register_die_notifier(&kprobe_exceptions_nb); | |
b94cce92 HN |
509 | /* Register the trampoline probe for return probe */ |
510 | register_kprobe(&trampoline_p); | |
1da177e4 LT |
511 | return err; |
512 | } | |
513 | ||
514 | __initcall(init_kprobes); | |
515 | ||
516 | EXPORT_SYMBOL_GPL(register_kprobe); | |
517 | EXPORT_SYMBOL_GPL(unregister_kprobe); | |
518 | EXPORT_SYMBOL_GPL(register_jprobe); | |
519 | EXPORT_SYMBOL_GPL(unregister_jprobe); | |
520 | EXPORT_SYMBOL_GPL(jprobe_return); | |
b94cce92 HN |
521 | EXPORT_SYMBOL_GPL(register_kretprobe); |
522 | EXPORT_SYMBOL_GPL(unregister_kretprobe); | |
523 |