Commit | Line | Data |
---|---|---|
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> | |
1da177e4 LT |
35 | #include <linux/hash.h> |
36 | #include <linux/init.h> | |
4e57b681 | 37 | #include <linux/slab.h> |
e3869792 | 38 | #include <linux/stddef.h> |
1da177e4 | 39 | #include <linux/module.h> |
9ec4b1f3 | 40 | #include <linux/moduleloader.h> |
3a872d89 | 41 | #include <linux/kallsyms.h> |
b4c6c34a | 42 | #include <linux/freezer.h> |
346fd59b SD |
43 | #include <linux/seq_file.h> |
44 | #include <linux/debugfs.h> | |
1eeb66a1 | 45 | #include <linux/kdebug.h> |
d0aaff97 | 46 | #include <asm-generic/sections.h> |
1da177e4 LT |
47 | #include <asm/cacheflush.h> |
48 | #include <asm/errno.h> | |
1da177e4 LT |
49 | |
50 | #define KPROBE_HASH_BITS 6 | |
51 | #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS) | |
52 | ||
3a872d89 AM |
53 | |
54 | /* | |
55 | * Some oddball architectures like 64bit powerpc have function descriptors | |
56 | * so this must be overridable. | |
57 | */ | |
58 | #ifndef kprobe_lookup_name | |
59 | #define kprobe_lookup_name(name, addr) \ | |
60 | addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name))) | |
61 | #endif | |
62 | ||
1da177e4 | 63 | static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; |
b94cce92 | 64 | static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE]; |
e6f47f97 | 65 | static atomic_t kprobe_count; |
1da177e4 | 66 | |
7a7d1cf9 | 67 | DEFINE_MUTEX(kprobe_mutex); /* Protects kprobe_table */ |
3516a460 | 68 | DEFINE_SPINLOCK(kretprobe_lock); /* Protects kretprobe_inst_table */ |
e6584523 | 69 | static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL; |
1da177e4 | 70 | |
e6f47f97 AK |
71 | static struct notifier_block kprobe_page_fault_nb = { |
72 | .notifier_call = kprobe_exceptions_notify, | |
73 | .priority = 0x7fffffff /* we need to notified first */ | |
74 | }; | |
75 | ||
2d14e39d | 76 | #ifdef __ARCH_WANT_KPROBES_INSN_SLOT |
9ec4b1f3 AM |
77 | /* |
78 | * kprobe->ainsn.insn points to the copy of the instruction to be | |
79 | * single-stepped. x86_64, POWER4 and above have no-exec support and | |
80 | * stepping on the instruction on a vmalloced/kmalloced/data page | |
81 | * is a recipe for disaster | |
82 | */ | |
83 | #define INSNS_PER_PAGE (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t))) | |
84 | ||
85 | struct kprobe_insn_page { | |
86 | struct hlist_node hlist; | |
87 | kprobe_opcode_t *insns; /* Page of instruction slots */ | |
88 | char slot_used[INSNS_PER_PAGE]; | |
89 | int nused; | |
b4c6c34a | 90 | int ngarbage; |
9ec4b1f3 AM |
91 | }; |
92 | ||
ab40c5c6 MH |
93 | enum kprobe_slot_state { |
94 | SLOT_CLEAN = 0, | |
95 | SLOT_DIRTY = 1, | |
96 | SLOT_USED = 2, | |
97 | }; | |
98 | ||
9ec4b1f3 | 99 | static struct hlist_head kprobe_insn_pages; |
b4c6c34a MH |
100 | static int kprobe_garbage_slots; |
101 | static int collect_garbage_slots(void); | |
102 | ||
103 | static int __kprobes check_safety(void) | |
104 | { | |
105 | int ret = 0; | |
106 | #if defined(CONFIG_PREEMPT) && defined(CONFIG_PM) | |
107 | ret = freeze_processes(); | |
108 | if (ret == 0) { | |
109 | struct task_struct *p, *q; | |
110 | do_each_thread(p, q) { | |
111 | if (p != current && p->state == TASK_RUNNING && | |
112 | p->pid != 0) { | |
113 | printk("Check failed: %s is running\n",p->comm); | |
114 | ret = -1; | |
115 | goto loop_end; | |
116 | } | |
117 | } while_each_thread(p, q); | |
118 | } | |
119 | loop_end: | |
120 | thaw_processes(); | |
121 | #else | |
122 | synchronize_sched(); | |
123 | #endif | |
124 | return ret; | |
125 | } | |
9ec4b1f3 AM |
126 | |
127 | /** | |
128 | * get_insn_slot() - Find a slot on an executable page for an instruction. | |
129 | * We allocate an executable page if there's no room on existing ones. | |
130 | */ | |
d0aaff97 | 131 | kprobe_opcode_t __kprobes *get_insn_slot(void) |
9ec4b1f3 AM |
132 | { |
133 | struct kprobe_insn_page *kip; | |
134 | struct hlist_node *pos; | |
135 | ||
b4c6c34a | 136 | retry: |
9ec4b1f3 AM |
137 | hlist_for_each(pos, &kprobe_insn_pages) { |
138 | kip = hlist_entry(pos, struct kprobe_insn_page, hlist); | |
139 | if (kip->nused < INSNS_PER_PAGE) { | |
140 | int i; | |
141 | for (i = 0; i < INSNS_PER_PAGE; i++) { | |
ab40c5c6 MH |
142 | if (kip->slot_used[i] == SLOT_CLEAN) { |
143 | kip->slot_used[i] = SLOT_USED; | |
9ec4b1f3 AM |
144 | kip->nused++; |
145 | return kip->insns + (i * MAX_INSN_SIZE); | |
146 | } | |
147 | } | |
148 | /* Surprise! No unused slots. Fix kip->nused. */ | |
149 | kip->nused = INSNS_PER_PAGE; | |
150 | } | |
151 | } | |
152 | ||
b4c6c34a MH |
153 | /* If there are any garbage slots, collect it and try again. */ |
154 | if (kprobe_garbage_slots && collect_garbage_slots() == 0) { | |
155 | goto retry; | |
156 | } | |
157 | /* All out of space. Need to allocate a new page. Use slot 0. */ | |
9ec4b1f3 AM |
158 | kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL); |
159 | if (!kip) { | |
160 | return NULL; | |
161 | } | |
162 | ||
163 | /* | |
164 | * Use module_alloc so this page is within +/- 2GB of where the | |
165 | * kernel image and loaded module images reside. This is required | |
166 | * so x86_64 can correctly handle the %rip-relative fixups. | |
167 | */ | |
168 | kip->insns = module_alloc(PAGE_SIZE); | |
169 | if (!kip->insns) { | |
170 | kfree(kip); | |
171 | return NULL; | |
172 | } | |
173 | INIT_HLIST_NODE(&kip->hlist); | |
174 | hlist_add_head(&kip->hlist, &kprobe_insn_pages); | |
ab40c5c6 MH |
175 | memset(kip->slot_used, SLOT_CLEAN, INSNS_PER_PAGE); |
176 | kip->slot_used[0] = SLOT_USED; | |
9ec4b1f3 | 177 | kip->nused = 1; |
b4c6c34a | 178 | kip->ngarbage = 0; |
9ec4b1f3 AM |
179 | return kip->insns; |
180 | } | |
181 | ||
b4c6c34a MH |
182 | /* Return 1 if all garbages are collected, otherwise 0. */ |
183 | static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx) | |
184 | { | |
ab40c5c6 | 185 | kip->slot_used[idx] = SLOT_CLEAN; |
b4c6c34a MH |
186 | kip->nused--; |
187 | if (kip->nused == 0) { | |
188 | /* | |
189 | * Page is no longer in use. Free it unless | |
190 | * it's the last one. We keep the last one | |
191 | * so as not to have to set it up again the | |
192 | * next time somebody inserts a probe. | |
193 | */ | |
194 | hlist_del(&kip->hlist); | |
195 | if (hlist_empty(&kprobe_insn_pages)) { | |
196 | INIT_HLIST_NODE(&kip->hlist); | |
197 | hlist_add_head(&kip->hlist, | |
198 | &kprobe_insn_pages); | |
199 | } else { | |
200 | module_free(NULL, kip->insns); | |
201 | kfree(kip); | |
202 | } | |
203 | return 1; | |
204 | } | |
205 | return 0; | |
206 | } | |
207 | ||
208 | static int __kprobes collect_garbage_slots(void) | |
209 | { | |
210 | struct kprobe_insn_page *kip; | |
211 | struct hlist_node *pos, *next; | |
212 | ||
213 | /* Ensure no-one is preepmted on the garbages */ | |
214 | if (check_safety() != 0) | |
215 | return -EAGAIN; | |
216 | ||
217 | hlist_for_each_safe(pos, next, &kprobe_insn_pages) { | |
218 | int i; | |
219 | kip = hlist_entry(pos, struct kprobe_insn_page, hlist); | |
220 | if (kip->ngarbage == 0) | |
221 | continue; | |
222 | kip->ngarbage = 0; /* we will collect all garbages */ | |
223 | for (i = 0; i < INSNS_PER_PAGE; i++) { | |
ab40c5c6 | 224 | if (kip->slot_used[i] == SLOT_DIRTY && |
b4c6c34a MH |
225 | collect_one_slot(kip, i)) |
226 | break; | |
227 | } | |
228 | } | |
229 | kprobe_garbage_slots = 0; | |
230 | return 0; | |
231 | } | |
232 | ||
233 | void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty) | |
9ec4b1f3 AM |
234 | { |
235 | struct kprobe_insn_page *kip; | |
236 | struct hlist_node *pos; | |
237 | ||
238 | hlist_for_each(pos, &kprobe_insn_pages) { | |
239 | kip = hlist_entry(pos, struct kprobe_insn_page, hlist); | |
240 | if (kip->insns <= slot && | |
241 | slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) { | |
242 | int i = (slot - kip->insns) / MAX_INSN_SIZE; | |
b4c6c34a | 243 | if (dirty) { |
ab40c5c6 | 244 | kip->slot_used[i] = SLOT_DIRTY; |
b4c6c34a MH |
245 | kip->ngarbage++; |
246 | } else { | |
247 | collect_one_slot(kip, i); | |
9ec4b1f3 | 248 | } |
b4c6c34a | 249 | break; |
9ec4b1f3 AM |
250 | } |
251 | } | |
b4c6c34a MH |
252 | if (dirty && (++kprobe_garbage_slots > INSNS_PER_PAGE)) { |
253 | collect_garbage_slots(); | |
254 | } | |
9ec4b1f3 | 255 | } |
2d14e39d | 256 | #endif |
9ec4b1f3 | 257 | |
e6584523 AM |
258 | /* We have preemption disabled.. so it is safe to use __ versions */ |
259 | static inline void set_kprobe_instance(struct kprobe *kp) | |
260 | { | |
261 | __get_cpu_var(kprobe_instance) = kp; | |
262 | } | |
263 | ||
264 | static inline void reset_kprobe_instance(void) | |
265 | { | |
266 | __get_cpu_var(kprobe_instance) = NULL; | |
267 | } | |
268 | ||
3516a460 AM |
269 | /* |
270 | * This routine is called either: | |
49a2a1b8 | 271 | * - under the kprobe_mutex - during kprobe_[un]register() |
3516a460 | 272 | * OR |
d217d545 | 273 | * - with preemption disabled - from arch/xxx/kernel/kprobes.c |
3516a460 | 274 | */ |
d0aaff97 | 275 | struct kprobe __kprobes *get_kprobe(void *addr) |
1da177e4 LT |
276 | { |
277 | struct hlist_head *head; | |
278 | struct hlist_node *node; | |
3516a460 | 279 | struct kprobe *p; |
1da177e4 LT |
280 | |
281 | head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)]; | |
3516a460 | 282 | hlist_for_each_entry_rcu(p, node, head, hlist) { |
1da177e4 LT |
283 | if (p->addr == addr) |
284 | return p; | |
285 | } | |
286 | return NULL; | |
287 | } | |
288 | ||
64f562c6 AM |
289 | /* |
290 | * Aggregate handlers for multiple kprobes support - these handlers | |
291 | * take care of invoking the individual kprobe handlers on p->list | |
292 | */ | |
d0aaff97 | 293 | static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs) |
64f562c6 AM |
294 | { |
295 | struct kprobe *kp; | |
296 | ||
3516a460 | 297 | list_for_each_entry_rcu(kp, &p->list, list) { |
64f562c6 | 298 | if (kp->pre_handler) { |
e6584523 | 299 | set_kprobe_instance(kp); |
8b0914ea PP |
300 | if (kp->pre_handler(kp, regs)) |
301 | return 1; | |
64f562c6 | 302 | } |
e6584523 | 303 | reset_kprobe_instance(); |
64f562c6 AM |
304 | } |
305 | return 0; | |
306 | } | |
307 | ||
d0aaff97 PP |
308 | static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs, |
309 | unsigned long flags) | |
64f562c6 AM |
310 | { |
311 | struct kprobe *kp; | |
312 | ||
3516a460 | 313 | list_for_each_entry_rcu(kp, &p->list, list) { |
64f562c6 | 314 | if (kp->post_handler) { |
e6584523 | 315 | set_kprobe_instance(kp); |
64f562c6 | 316 | kp->post_handler(kp, regs, flags); |
e6584523 | 317 | reset_kprobe_instance(); |
64f562c6 AM |
318 | } |
319 | } | |
320 | return; | |
321 | } | |
322 | ||
d0aaff97 PP |
323 | static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs, |
324 | int trapnr) | |
64f562c6 | 325 | { |
e6584523 AM |
326 | struct kprobe *cur = __get_cpu_var(kprobe_instance); |
327 | ||
64f562c6 AM |
328 | /* |
329 | * if we faulted "during" the execution of a user specified | |
330 | * probe handler, invoke just that probe's fault handler | |
331 | */ | |
e6584523 AM |
332 | if (cur && cur->fault_handler) { |
333 | if (cur->fault_handler(cur, regs, trapnr)) | |
64f562c6 AM |
334 | return 1; |
335 | } | |
336 | return 0; | |
337 | } | |
338 | ||
d0aaff97 | 339 | static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs) |
8b0914ea | 340 | { |
e6584523 AM |
341 | struct kprobe *cur = __get_cpu_var(kprobe_instance); |
342 | int ret = 0; | |
343 | ||
344 | if (cur && cur->break_handler) { | |
345 | if (cur->break_handler(cur, regs)) | |
346 | ret = 1; | |
8b0914ea | 347 | } |
e6584523 AM |
348 | reset_kprobe_instance(); |
349 | return ret; | |
8b0914ea PP |
350 | } |
351 | ||
bf8d5c52 KA |
352 | /* Walks the list and increments nmissed count for multiprobe case */ |
353 | void __kprobes kprobes_inc_nmissed_count(struct kprobe *p) | |
354 | { | |
355 | struct kprobe *kp; | |
356 | if (p->pre_handler != aggr_pre_handler) { | |
357 | p->nmissed++; | |
358 | } else { | |
359 | list_for_each_entry_rcu(kp, &p->list, list) | |
360 | kp->nmissed++; | |
361 | } | |
362 | return; | |
363 | } | |
364 | ||
3516a460 | 365 | /* Called with kretprobe_lock held */ |
d0aaff97 | 366 | struct kretprobe_instance __kprobes *get_free_rp_inst(struct kretprobe *rp) |
b94cce92 HN |
367 | { |
368 | struct hlist_node *node; | |
369 | struct kretprobe_instance *ri; | |
370 | hlist_for_each_entry(ri, node, &rp->free_instances, uflist) | |
371 | return ri; | |
372 | return NULL; | |
373 | } | |
374 | ||
3516a460 | 375 | /* Called with kretprobe_lock held */ |
d0aaff97 PP |
376 | static struct kretprobe_instance __kprobes *get_used_rp_inst(struct kretprobe |
377 | *rp) | |
b94cce92 HN |
378 | { |
379 | struct hlist_node *node; | |
380 | struct kretprobe_instance *ri; | |
381 | hlist_for_each_entry(ri, node, &rp->used_instances, uflist) | |
382 | return ri; | |
383 | return NULL; | |
384 | } | |
385 | ||
3516a460 | 386 | /* Called with kretprobe_lock held */ |
d0aaff97 | 387 | void __kprobes add_rp_inst(struct kretprobe_instance *ri) |
b94cce92 | 388 | { |
b94cce92 HN |
389 | /* |
390 | * Remove rp inst off the free list - | |
391 | * Add it back when probed function returns | |
392 | */ | |
393 | hlist_del(&ri->uflist); | |
802eae7c | 394 | |
b94cce92 HN |
395 | /* Add rp inst onto table */ |
396 | INIT_HLIST_NODE(&ri->hlist); | |
397 | hlist_add_head(&ri->hlist, | |
802eae7c | 398 | &kretprobe_inst_table[hash_ptr(ri->task, KPROBE_HASH_BITS)]); |
b94cce92 HN |
399 | |
400 | /* Also add this rp inst to the used list. */ | |
401 | INIT_HLIST_NODE(&ri->uflist); | |
402 | hlist_add_head(&ri->uflist, &ri->rp->used_instances); | |
403 | } | |
404 | ||
3516a460 | 405 | /* Called with kretprobe_lock held */ |
99219a3f | 406 | void __kprobes recycle_rp_inst(struct kretprobe_instance *ri, |
407 | struct hlist_head *head) | |
b94cce92 HN |
408 | { |
409 | /* remove rp inst off the rprobe_inst_table */ | |
410 | hlist_del(&ri->hlist); | |
411 | if (ri->rp) { | |
412 | /* remove rp inst off the used list */ | |
413 | hlist_del(&ri->uflist); | |
414 | /* put rp inst back onto the free list */ | |
415 | INIT_HLIST_NODE(&ri->uflist); | |
416 | hlist_add_head(&ri->uflist, &ri->rp->free_instances); | |
417 | } else | |
418 | /* Unregistering */ | |
99219a3f | 419 | hlist_add_head(&ri->hlist, head); |
b94cce92 HN |
420 | } |
421 | ||
d0aaff97 | 422 | struct hlist_head __kprobes *kretprobe_inst_table_head(struct task_struct *tsk) |
b94cce92 HN |
423 | { |
424 | return &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)]; | |
425 | } | |
426 | ||
b94cce92 | 427 | /* |
c6fd91f0 | 428 | * This function is called from finish_task_switch when task tk becomes dead, |
429 | * so that we can recycle any function-return probe instances associated | |
430 | * with this task. These left over instances represent probed functions | |
431 | * that have been called but will never return. | |
b94cce92 | 432 | */ |
d0aaff97 | 433 | void __kprobes kprobe_flush_task(struct task_struct *tk) |
b94cce92 | 434 | { |
62c27be0 | 435 | struct kretprobe_instance *ri; |
99219a3f | 436 | struct hlist_head *head, empty_rp; |
802eae7c | 437 | struct hlist_node *node, *tmp; |
0aa55e4d | 438 | unsigned long flags = 0; |
802eae7c | 439 | |
99219a3f | 440 | INIT_HLIST_HEAD(&empty_rp); |
3516a460 | 441 | spin_lock_irqsave(&kretprobe_lock, flags); |
62c27be0 | 442 | head = kretprobe_inst_table_head(tk); |
443 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { | |
444 | if (ri->task == tk) | |
99219a3f | 445 | recycle_rp_inst(ri, &empty_rp); |
62c27be0 | 446 | } |
3516a460 | 447 | spin_unlock_irqrestore(&kretprobe_lock, flags); |
99219a3f | 448 | |
449 | hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { | |
450 | hlist_del(&ri->hlist); | |
451 | kfree(ri); | |
452 | } | |
b94cce92 HN |
453 | } |
454 | ||
b94cce92 HN |
455 | static inline void free_rp_inst(struct kretprobe *rp) |
456 | { | |
457 | struct kretprobe_instance *ri; | |
458 | while ((ri = get_free_rp_inst(rp)) != NULL) { | |
459 | hlist_del(&ri->uflist); | |
460 | kfree(ri); | |
461 | } | |
462 | } | |
463 | ||
8b0914ea PP |
464 | /* |
465 | * Keep all fields in the kprobe consistent | |
466 | */ | |
467 | static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p) | |
468 | { | |
469 | memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t)); | |
470 | memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn)); | |
471 | } | |
472 | ||
473 | /* | |
474 | * Add the new probe to old_p->list. Fail if this is the | |
475 | * second jprobe at the address - two jprobes can't coexist | |
476 | */ | |
d0aaff97 | 477 | static int __kprobes add_new_kprobe(struct kprobe *old_p, struct kprobe *p) |
8b0914ea | 478 | { |
8b0914ea | 479 | if (p->break_handler) { |
36721656 | 480 | if (old_p->break_handler) |
481 | return -EEXIST; | |
3516a460 | 482 | list_add_tail_rcu(&p->list, &old_p->list); |
36721656 | 483 | old_p->break_handler = aggr_break_handler; |
8b0914ea | 484 | } else |
3516a460 | 485 | list_add_rcu(&p->list, &old_p->list); |
36721656 | 486 | if (p->post_handler && !old_p->post_handler) |
487 | old_p->post_handler = aggr_post_handler; | |
8b0914ea PP |
488 | return 0; |
489 | } | |
490 | ||
64f562c6 AM |
491 | /* |
492 | * Fill in the required fields of the "manager kprobe". Replace the | |
493 | * earlier kprobe in the hlist with the manager kprobe | |
494 | */ | |
495 | static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p) | |
496 | { | |
8b0914ea | 497 | copy_kprobe(p, ap); |
a9ad965e | 498 | flush_insn_slot(ap); |
64f562c6 | 499 | ap->addr = p->addr; |
64f562c6 | 500 | ap->pre_handler = aggr_pre_handler; |
64f562c6 | 501 | ap->fault_handler = aggr_fault_handler; |
36721656 | 502 | if (p->post_handler) |
503 | ap->post_handler = aggr_post_handler; | |
504 | if (p->break_handler) | |
505 | ap->break_handler = aggr_break_handler; | |
64f562c6 AM |
506 | |
507 | INIT_LIST_HEAD(&ap->list); | |
3516a460 | 508 | list_add_rcu(&p->list, &ap->list); |
64f562c6 | 509 | |
adad0f33 | 510 | hlist_replace_rcu(&p->hlist, &ap->hlist); |
64f562c6 AM |
511 | } |
512 | ||
513 | /* | |
514 | * This is the second or subsequent kprobe at the address - handle | |
515 | * the intricacies | |
64f562c6 | 516 | */ |
d0aaff97 PP |
517 | static int __kprobes register_aggr_kprobe(struct kprobe *old_p, |
518 | struct kprobe *p) | |
64f562c6 AM |
519 | { |
520 | int ret = 0; | |
521 | struct kprobe *ap; | |
522 | ||
8b0914ea PP |
523 | if (old_p->pre_handler == aggr_pre_handler) { |
524 | copy_kprobe(old_p, p); | |
525 | ret = add_new_kprobe(old_p, p); | |
64f562c6 | 526 | } else { |
a0d50069 | 527 | ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL); |
64f562c6 AM |
528 | if (!ap) |
529 | return -ENOMEM; | |
530 | add_aggr_kprobe(ap, old_p); | |
8b0914ea PP |
531 | copy_kprobe(ap, p); |
532 | ret = add_new_kprobe(ap, p); | |
64f562c6 AM |
533 | } |
534 | return ret; | |
535 | } | |
536 | ||
d0aaff97 PP |
537 | static int __kprobes in_kprobes_functions(unsigned long addr) |
538 | { | |
539 | if (addr >= (unsigned long)__kprobes_text_start | |
540 | && addr < (unsigned long)__kprobes_text_end) | |
541 | return -EINVAL; | |
542 | return 0; | |
543 | } | |
544 | ||
df019b1d KA |
545 | static int __kprobes __register_kprobe(struct kprobe *p, |
546 | unsigned long called_from) | |
1da177e4 LT |
547 | { |
548 | int ret = 0; | |
64f562c6 | 549 | struct kprobe *old_p; |
df019b1d | 550 | struct module *probed_mod; |
b3e55c72 | 551 | |
3a872d89 AM |
552 | /* |
553 | * If we have a symbol_name argument look it up, | |
554 | * and add it to the address. That way the addr | |
555 | * field can either be global or relative to a symbol. | |
556 | */ | |
557 | if (p->symbol_name) { | |
558 | if (p->addr) | |
559 | return -EINVAL; | |
560 | kprobe_lookup_name(p->symbol_name, p->addr); | |
561 | } | |
562 | ||
563 | if (!p->addr) | |
564 | return -EINVAL; | |
565 | p->addr = (kprobe_opcode_t *)(((char *)p->addr)+ p->offset); | |
566 | ||
b3e55c72 MB |
567 | if ((!kernel_text_address((unsigned long) p->addr)) || |
568 | in_kprobes_functions((unsigned long) p->addr)) | |
569 | return -EINVAL; | |
570 | ||
df019b1d KA |
571 | p->mod_refcounted = 0; |
572 | /* Check are we probing a module */ | |
573 | if ((probed_mod = module_text_address((unsigned long) p->addr))) { | |
574 | struct module *calling_mod = module_text_address(called_from); | |
575 | /* We must allow modules to probe themself and | |
576 | * in this case avoid incrementing the module refcount, | |
577 | * so as to allow unloading of self probing modules. | |
578 | */ | |
579 | if (calling_mod && (calling_mod != probed_mod)) { | |
580 | if (unlikely(!try_module_get(probed_mod))) | |
581 | return -EINVAL; | |
582 | p->mod_refcounted = 1; | |
583 | } else | |
584 | probed_mod = NULL; | |
585 | } | |
1da177e4 | 586 | |
3516a460 | 587 | p->nmissed = 0; |
7a7d1cf9 | 588 | mutex_lock(&kprobe_mutex); |
64f562c6 AM |
589 | old_p = get_kprobe(p->addr); |
590 | if (old_p) { | |
591 | ret = register_aggr_kprobe(old_p, p); | |
e6f47f97 AK |
592 | if (!ret) |
593 | atomic_inc(&kprobe_count); | |
1da177e4 LT |
594 | goto out; |
595 | } | |
1da177e4 | 596 | |
49a2a1b8 AK |
597 | if ((ret = arch_prepare_kprobe(p)) != 0) |
598 | goto out; | |
599 | ||
64f562c6 | 600 | INIT_HLIST_NODE(&p->hlist); |
3516a460 | 601 | hlist_add_head_rcu(&p->hlist, |
1da177e4 LT |
602 | &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]); |
603 | ||
e6f47f97 AK |
604 | if (atomic_add_return(1, &kprobe_count) == \ |
605 | (ARCH_INACTIVE_KPROBE_COUNT + 1)) | |
606 | register_page_fault_notifier(&kprobe_page_fault_nb); | |
607 | ||
62c27be0 | 608 | arch_arm_kprobe(p); |
7e1048b1 | 609 | |
1da177e4 | 610 | out: |
7a7d1cf9 | 611 | mutex_unlock(&kprobe_mutex); |
49a2a1b8 | 612 | |
df019b1d KA |
613 | if (ret && probed_mod) |
614 | module_put(probed_mod); | |
1da177e4 LT |
615 | return ret; |
616 | } | |
617 | ||
df019b1d KA |
618 | int __kprobes register_kprobe(struct kprobe *p) |
619 | { | |
620 | return __register_kprobe(p, | |
621 | (unsigned long)__builtin_return_address(0)); | |
622 | } | |
623 | ||
d0aaff97 | 624 | void __kprobes unregister_kprobe(struct kprobe *p) |
1da177e4 | 625 | { |
b3e55c72 | 626 | struct module *mod; |
f709b122 KA |
627 | struct kprobe *old_p, *list_p; |
628 | int cleanup_p; | |
64f562c6 | 629 | |
7a7d1cf9 | 630 | mutex_lock(&kprobe_mutex); |
64f562c6 | 631 | old_p = get_kprobe(p->addr); |
49a2a1b8 | 632 | if (unlikely(!old_p)) { |
7a7d1cf9 | 633 | mutex_unlock(&kprobe_mutex); |
49a2a1b8 AK |
634 | return; |
635 | } | |
f709b122 KA |
636 | if (p != old_p) { |
637 | list_for_each_entry_rcu(list_p, &old_p->list, list) | |
638 | if (list_p == p) | |
639 | /* kprobe p is a valid probe */ | |
640 | goto valid_p; | |
7a7d1cf9 | 641 | mutex_unlock(&kprobe_mutex); |
f709b122 KA |
642 | return; |
643 | } | |
644 | valid_p: | |
645 | if ((old_p == p) || ((old_p->pre_handler == aggr_pre_handler) && | |
49a2a1b8 | 646 | (p->list.next == &old_p->list) && |
f709b122 KA |
647 | (p->list.prev == &old_p->list))) { |
648 | /* Only probe on the hash list */ | |
49a2a1b8 AK |
649 | arch_disarm_kprobe(p); |
650 | hlist_del_rcu(&old_p->hlist); | |
f709b122 | 651 | cleanup_p = 1; |
49a2a1b8 AK |
652 | } else { |
653 | list_del_rcu(&p->list); | |
f709b122 | 654 | cleanup_p = 0; |
49a2a1b8 | 655 | } |
3516a460 | 656 | |
7a7d1cf9 | 657 | mutex_unlock(&kprobe_mutex); |
b3e55c72 | 658 | |
49a2a1b8 | 659 | synchronize_sched(); |
df019b1d KA |
660 | if (p->mod_refcounted && |
661 | (mod = module_text_address((unsigned long)p->addr))) | |
49a2a1b8 | 662 | module_put(mod); |
b3e55c72 | 663 | |
49a2a1b8 | 664 | if (cleanup_p) { |
f709b122 | 665 | if (p != old_p) { |
49a2a1b8 | 666 | list_del_rcu(&p->list); |
3516a460 | 667 | kfree(old_p); |
49a2a1b8 | 668 | } |
0498b635 | 669 | arch_remove_kprobe(p); |
36721656 | 670 | } else { |
671 | mutex_lock(&kprobe_mutex); | |
672 | if (p->break_handler) | |
673 | old_p->break_handler = NULL; | |
674 | if (p->post_handler){ | |
675 | list_for_each_entry_rcu(list_p, &old_p->list, list){ | |
676 | if (list_p->post_handler){ | |
677 | cleanup_p = 2; | |
678 | break; | |
679 | } | |
680 | } | |
681 | if (cleanup_p == 0) | |
682 | old_p->post_handler = NULL; | |
683 | } | |
684 | mutex_unlock(&kprobe_mutex); | |
49a2a1b8 | 685 | } |
e6f47f97 AK |
686 | |
687 | /* Call unregister_page_fault_notifier() | |
688 | * if no probes are active | |
689 | */ | |
690 | mutex_lock(&kprobe_mutex); | |
691 | if (atomic_add_return(-1, &kprobe_count) == \ | |
692 | ARCH_INACTIVE_KPROBE_COUNT) | |
693 | unregister_page_fault_notifier(&kprobe_page_fault_nb); | |
694 | mutex_unlock(&kprobe_mutex); | |
695 | return; | |
1da177e4 LT |
696 | } |
697 | ||
698 | static struct notifier_block kprobe_exceptions_nb = { | |
3d5631e0 AK |
699 | .notifier_call = kprobe_exceptions_notify, |
700 | .priority = 0x7fffffff /* we need to be notified first */ | |
701 | }; | |
702 | ||
1da177e4 | 703 | |
d0aaff97 | 704 | int __kprobes register_jprobe(struct jprobe *jp) |
1da177e4 LT |
705 | { |
706 | /* Todo: Verify probepoint is a function entry point */ | |
707 | jp->kp.pre_handler = setjmp_pre_handler; | |
708 | jp->kp.break_handler = longjmp_break_handler; | |
709 | ||
df019b1d KA |
710 | return __register_kprobe(&jp->kp, |
711 | (unsigned long)__builtin_return_address(0)); | |
1da177e4 LT |
712 | } |
713 | ||
d0aaff97 | 714 | void __kprobes unregister_jprobe(struct jprobe *jp) |
1da177e4 LT |
715 | { |
716 | unregister_kprobe(&jp->kp); | |
717 | } | |
718 | ||
b94cce92 HN |
719 | #ifdef ARCH_SUPPORTS_KRETPROBES |
720 | ||
e65cefe8 AB |
721 | /* |
722 | * This kprobe pre_handler is registered with every kretprobe. When probe | |
723 | * hits it will set up the return probe. | |
724 | */ | |
725 | static int __kprobes pre_handler_kretprobe(struct kprobe *p, | |
726 | struct pt_regs *regs) | |
727 | { | |
728 | struct kretprobe *rp = container_of(p, struct kretprobe, kp); | |
729 | unsigned long flags = 0; | |
730 | ||
731 | /*TODO: consider to only swap the RA after the last pre_handler fired */ | |
732 | spin_lock_irqsave(&kretprobe_lock, flags); | |
733 | arch_prepare_kretprobe(rp, regs); | |
734 | spin_unlock_irqrestore(&kretprobe_lock, flags); | |
735 | return 0; | |
736 | } | |
737 | ||
d0aaff97 | 738 | int __kprobes register_kretprobe(struct kretprobe *rp) |
b94cce92 HN |
739 | { |
740 | int ret = 0; | |
741 | struct kretprobe_instance *inst; | |
742 | int i; | |
743 | ||
744 | rp->kp.pre_handler = pre_handler_kretprobe; | |
7522a842 AM |
745 | rp->kp.post_handler = NULL; |
746 | rp->kp.fault_handler = NULL; | |
747 | rp->kp.break_handler = NULL; | |
b94cce92 HN |
748 | |
749 | /* Pre-allocate memory for max kretprobe instances */ | |
750 | if (rp->maxactive <= 0) { | |
751 | #ifdef CONFIG_PREEMPT | |
752 | rp->maxactive = max(10, 2 * NR_CPUS); | |
753 | #else | |
754 | rp->maxactive = NR_CPUS; | |
755 | #endif | |
756 | } | |
757 | INIT_HLIST_HEAD(&rp->used_instances); | |
758 | INIT_HLIST_HEAD(&rp->free_instances); | |
759 | for (i = 0; i < rp->maxactive; i++) { | |
760 | inst = kmalloc(sizeof(struct kretprobe_instance), GFP_KERNEL); | |
761 | if (inst == NULL) { | |
762 | free_rp_inst(rp); | |
763 | return -ENOMEM; | |
764 | } | |
765 | INIT_HLIST_NODE(&inst->uflist); | |
766 | hlist_add_head(&inst->uflist, &rp->free_instances); | |
767 | } | |
768 | ||
769 | rp->nmissed = 0; | |
770 | /* Establish function entry probe point */ | |
df019b1d KA |
771 | if ((ret = __register_kprobe(&rp->kp, |
772 | (unsigned long)__builtin_return_address(0))) != 0) | |
b94cce92 HN |
773 | free_rp_inst(rp); |
774 | return ret; | |
775 | } | |
776 | ||
777 | #else /* ARCH_SUPPORTS_KRETPROBES */ | |
778 | ||
d0aaff97 | 779 | int __kprobes register_kretprobe(struct kretprobe *rp) |
b94cce92 HN |
780 | { |
781 | return -ENOSYS; | |
782 | } | |
783 | ||
346fd59b SD |
784 | static int __kprobes pre_handler_kretprobe(struct kprobe *p, |
785 | struct pt_regs *regs) | |
786 | { | |
787 | return 0; | |
788 | } | |
789 | ||
b94cce92 HN |
790 | #endif /* ARCH_SUPPORTS_KRETPROBES */ |
791 | ||
d0aaff97 | 792 | void __kprobes unregister_kretprobe(struct kretprobe *rp) |
b94cce92 HN |
793 | { |
794 | unsigned long flags; | |
795 | struct kretprobe_instance *ri; | |
796 | ||
797 | unregister_kprobe(&rp->kp); | |
798 | /* No race here */ | |
3516a460 | 799 | spin_lock_irqsave(&kretprobe_lock, flags); |
b94cce92 HN |
800 | while ((ri = get_used_rp_inst(rp)) != NULL) { |
801 | ri->rp = NULL; | |
802 | hlist_del(&ri->uflist); | |
803 | } | |
3516a460 | 804 | spin_unlock_irqrestore(&kretprobe_lock, flags); |
278ff953 | 805 | free_rp_inst(rp); |
b94cce92 HN |
806 | } |
807 | ||
1da177e4 LT |
808 | static int __init init_kprobes(void) |
809 | { | |
810 | int i, err = 0; | |
811 | ||
812 | /* FIXME allocate the probe table, currently defined statically */ | |
813 | /* initialize all list heads */ | |
b94cce92 | 814 | for (i = 0; i < KPROBE_TABLE_SIZE; i++) { |
1da177e4 | 815 | INIT_HLIST_HEAD(&kprobe_table[i]); |
b94cce92 HN |
816 | INIT_HLIST_HEAD(&kretprobe_inst_table[i]); |
817 | } | |
e6f47f97 | 818 | atomic_set(&kprobe_count, 0); |
1da177e4 | 819 | |
6772926b | 820 | err = arch_init_kprobes(); |
802eae7c RL |
821 | if (!err) |
822 | err = register_die_notifier(&kprobe_exceptions_nb); | |
823 | ||
1da177e4 LT |
824 | return err; |
825 | } | |
826 | ||
346fd59b SD |
827 | #ifdef CONFIG_DEBUG_FS |
828 | static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p, | |
829 | const char *sym, int offset,char *modname) | |
830 | { | |
831 | char *kprobe_type; | |
832 | ||
833 | if (p->pre_handler == pre_handler_kretprobe) | |
834 | kprobe_type = "r"; | |
835 | else if (p->pre_handler == setjmp_pre_handler) | |
836 | kprobe_type = "j"; | |
837 | else | |
838 | kprobe_type = "k"; | |
839 | if (sym) | |
840 | seq_printf(pi, "%p %s %s+0x%x %s\n", p->addr, kprobe_type, | |
841 | sym, offset, (modname ? modname : " ")); | |
842 | else | |
843 | seq_printf(pi, "%p %s %p\n", p->addr, kprobe_type, p->addr); | |
844 | } | |
845 | ||
846 | static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos) | |
847 | { | |
848 | return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL; | |
849 | } | |
850 | ||
851 | static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos) | |
852 | { | |
853 | (*pos)++; | |
854 | if (*pos >= KPROBE_TABLE_SIZE) | |
855 | return NULL; | |
856 | return pos; | |
857 | } | |
858 | ||
859 | static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v) | |
860 | { | |
861 | /* Nothing to do */ | |
862 | } | |
863 | ||
864 | static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v) | |
865 | { | |
866 | struct hlist_head *head; | |
867 | struct hlist_node *node; | |
868 | struct kprobe *p, *kp; | |
869 | const char *sym = NULL; | |
870 | unsigned int i = *(loff_t *) v; | |
871 | unsigned long size, offset = 0; | |
872 | char *modname, namebuf[128]; | |
873 | ||
874 | head = &kprobe_table[i]; | |
875 | preempt_disable(); | |
876 | hlist_for_each_entry_rcu(p, node, head, hlist) { | |
877 | sym = kallsyms_lookup((unsigned long)p->addr, &size, | |
878 | &offset, &modname, namebuf); | |
879 | if (p->pre_handler == aggr_pre_handler) { | |
880 | list_for_each_entry_rcu(kp, &p->list, list) | |
881 | report_probe(pi, kp, sym, offset, modname); | |
882 | } else | |
883 | report_probe(pi, p, sym, offset, modname); | |
884 | } | |
885 | preempt_enable(); | |
886 | return 0; | |
887 | } | |
888 | ||
889 | static struct seq_operations kprobes_seq_ops = { | |
890 | .start = kprobe_seq_start, | |
891 | .next = kprobe_seq_next, | |
892 | .stop = kprobe_seq_stop, | |
893 | .show = show_kprobe_addr | |
894 | }; | |
895 | ||
896 | static int __kprobes kprobes_open(struct inode *inode, struct file *filp) | |
897 | { | |
898 | return seq_open(filp, &kprobes_seq_ops); | |
899 | } | |
900 | ||
901 | static struct file_operations debugfs_kprobes_operations = { | |
902 | .open = kprobes_open, | |
903 | .read = seq_read, | |
904 | .llseek = seq_lseek, | |
905 | .release = seq_release, | |
906 | }; | |
907 | ||
908 | static int __kprobes debugfs_kprobe_init(void) | |
909 | { | |
910 | struct dentry *dir, *file; | |
911 | ||
912 | dir = debugfs_create_dir("kprobes", NULL); | |
913 | if (!dir) | |
914 | return -ENOMEM; | |
915 | ||
e3869792 | 916 | file = debugfs_create_file("list", 0444, dir, NULL, |
346fd59b SD |
917 | &debugfs_kprobes_operations); |
918 | if (!file) { | |
919 | debugfs_remove(dir); | |
920 | return -ENOMEM; | |
921 | } | |
922 | ||
923 | return 0; | |
924 | } | |
925 | ||
926 | late_initcall(debugfs_kprobe_init); | |
927 | #endif /* CONFIG_DEBUG_FS */ | |
928 | ||
929 | module_init(init_kprobes); | |
1da177e4 LT |
930 | |
931 | EXPORT_SYMBOL_GPL(register_kprobe); | |
932 | EXPORT_SYMBOL_GPL(unregister_kprobe); | |
933 | EXPORT_SYMBOL_GPL(register_jprobe); | |
934 | EXPORT_SYMBOL_GPL(unregister_jprobe); | |
935 | EXPORT_SYMBOL_GPL(jprobe_return); | |
b94cce92 HN |
936 | EXPORT_SYMBOL_GPL(register_kretprobe); |
937 | EXPORT_SYMBOL_GPL(unregister_kretprobe); |