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