Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * Kernel Probes (KProbes) | |
1da177e4 LT |
3 | * |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2 of the License, or | |
7 | * (at your option) any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program; if not, write to the Free Software | |
16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
17 | * | |
18 | * Copyright (C) IBM Corporation, 2002, 2004 | |
19 | * | |
20 | * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel | |
21 | * Probes initial implementation ( includes contributions from | |
22 | * Rusty Russell). | |
23 | * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes | |
24 | * interface to access function arguments. | |
25 | * 2004-Nov Ananth N Mavinakayanahalli <ananth@in.ibm.com> kprobes port | |
26 | * for PPC64 | |
27 | */ | |
28 | ||
29 | #include <linux/config.h> | |
30 | #include <linux/kprobes.h> | |
31 | #include <linux/ptrace.h> | |
1da177e4 | 32 | #include <linux/preempt.h> |
7e1048b1 | 33 | #include <asm/cacheflush.h> |
1da177e4 LT |
34 | #include <asm/kdebug.h> |
35 | #include <asm/sstep.h> | |
36 | ||
0dc036c9 AM |
37 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
38 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); | |
1da177e4 | 39 | |
bb144a85 | 40 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
1da177e4 | 41 | { |
63224d1e | 42 | int ret = 0; |
1da177e4 LT |
43 | kprobe_opcode_t insn = *p->addr; |
44 | ||
63224d1e AM |
45 | if ((unsigned long)p->addr & 0x03) { |
46 | printk("Attempt to register kprobe at an unaligned address\n"); | |
47 | ret = -EINVAL; | |
48 | } else if (IS_MTMSRD(insn) || IS_RFID(insn)) { | |
49 | printk("Cannot register a kprobe on rfid or mtmsrd\n"); | |
50 | ret = -EINVAL; | |
51 | } | |
9ec4b1f3 AM |
52 | |
53 | /* insn must be on a special executable page on ppc64 */ | |
54 | if (!ret) { | |
2d8ab6ad | 55 | p->ainsn.insn = get_insn_slot(); |
9ec4b1f3 AM |
56 | if (!p->ainsn.insn) |
57 | ret = -ENOMEM; | |
58 | } | |
1da177e4 | 59 | |
49a2a1b8 AK |
60 | if (!ret) { |
61 | memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); | |
62 | p->opcode = *p->addr; | |
63 | } | |
64 | ||
65 | return ret; | |
1da177e4 LT |
66 | } |
67 | ||
bb144a85 | 68 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
1da177e4 | 69 | { |
7e1048b1 RL |
70 | *p->addr = BREAKPOINT_INSTRUCTION; |
71 | flush_icache_range((unsigned long) p->addr, | |
72 | (unsigned long) p->addr + sizeof(kprobe_opcode_t)); | |
1da177e4 LT |
73 | } |
74 | ||
bb144a85 | 75 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
1da177e4 LT |
76 | { |
77 | *p->addr = p->opcode; | |
7e1048b1 RL |
78 | flush_icache_range((unsigned long) p->addr, |
79 | (unsigned long) p->addr + sizeof(kprobe_opcode_t)); | |
80 | } | |
81 | ||
0498b635 | 82 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
7e1048b1 | 83 | { |
7a7d1cf9 | 84 | mutex_lock(&kprobe_mutex); |
2d8ab6ad | 85 | free_insn_slot(p->ainsn.insn); |
7a7d1cf9 | 86 | mutex_unlock(&kprobe_mutex); |
1da177e4 LT |
87 | } |
88 | ||
89 | static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs) | |
90 | { | |
9ec4b1f3 AM |
91 | kprobe_opcode_t insn = *p->ainsn.insn; |
92 | ||
1da177e4 | 93 | regs->msr |= MSR_SE; |
9ec4b1f3 AM |
94 | |
95 | /* single step inline if it is a trap variant */ | |
deac66ae | 96 | if (is_trap(insn)) |
1da177e4 LT |
97 | regs->nip = (unsigned long)p->addr; |
98 | else | |
9ec4b1f3 | 99 | regs->nip = (unsigned long)p->ainsn.insn; |
1da177e4 LT |
100 | } |
101 | ||
0dc036c9 AM |
102 | static inline void save_previous_kprobe(struct kprobe_ctlblk *kcb) |
103 | { | |
104 | kcb->prev_kprobe.kp = kprobe_running(); | |
105 | kcb->prev_kprobe.status = kcb->kprobe_status; | |
106 | kcb->prev_kprobe.saved_msr = kcb->kprobe_saved_msr; | |
107 | } | |
108 | ||
109 | static inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb) | |
42cc2060 | 110 | { |
0dc036c9 AM |
111 | __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; |
112 | kcb->kprobe_status = kcb->prev_kprobe.status; | |
113 | kcb->kprobe_saved_msr = kcb->prev_kprobe.saved_msr; | |
42cc2060 PP |
114 | } |
115 | ||
0dc036c9 AM |
116 | static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
117 | struct kprobe_ctlblk *kcb) | |
42cc2060 | 118 | { |
0dc036c9 AM |
119 | __get_cpu_var(current_kprobe) = p; |
120 | kcb->kprobe_saved_msr = regs->msr; | |
42cc2060 PP |
121 | } |
122 | ||
991a51d8 | 123 | /* Called with kretprobe_lock held */ |
bb144a85 PP |
124 | void __kprobes arch_prepare_kretprobe(struct kretprobe *rp, |
125 | struct pt_regs *regs) | |
97f7943d RL |
126 | { |
127 | struct kretprobe_instance *ri; | |
128 | ||
129 | if ((ri = get_free_rp_inst(rp)) != NULL) { | |
130 | ri->rp = rp; | |
131 | ri->task = current; | |
132 | ri->ret_addr = (kprobe_opcode_t *)regs->link; | |
133 | ||
134 | /* Replace the return addr with trampoline addr */ | |
135 | regs->link = (unsigned long)kretprobe_trampoline; | |
136 | add_rp_inst(ri); | |
137 | } else { | |
138 | rp->nmissed++; | |
139 | } | |
140 | } | |
141 | ||
1da177e4 LT |
142 | static inline int kprobe_handler(struct pt_regs *regs) |
143 | { | |
144 | struct kprobe *p; | |
145 | int ret = 0; | |
146 | unsigned int *addr = (unsigned int *)regs->nip; | |
d217d545 AM |
147 | struct kprobe_ctlblk *kcb; |
148 | ||
149 | /* | |
150 | * We don't want to be preempted for the entire | |
151 | * duration of kprobe processing | |
152 | */ | |
153 | preempt_disable(); | |
154 | kcb = get_kprobe_ctlblk(); | |
1da177e4 LT |
155 | |
156 | /* Check we're not actually recursing */ | |
157 | if (kprobe_running()) { | |
1da177e4 LT |
158 | p = get_kprobe(addr); |
159 | if (p) { | |
deac66ae | 160 | kprobe_opcode_t insn = *p->ainsn.insn; |
0dc036c9 | 161 | if (kcb->kprobe_status == KPROBE_HIT_SS && |
deac66ae | 162 | is_trap(insn)) { |
1da177e4 | 163 | regs->msr &= ~MSR_SE; |
0dc036c9 | 164 | regs->msr |= kcb->kprobe_saved_msr; |
1da177e4 LT |
165 | goto no_kprobe; |
166 | } | |
42cc2060 PP |
167 | /* We have reentered the kprobe_handler(), since |
168 | * another probe was hit while within the handler. | |
169 | * We here save the original kprobes variables and | |
170 | * just single step on the instruction of the new probe | |
171 | * without calling any user handlers. | |
172 | */ | |
0dc036c9 AM |
173 | save_previous_kprobe(kcb); |
174 | set_current_kprobe(p, regs, kcb); | |
175 | kcb->kprobe_saved_msr = regs->msr; | |
bf8d5c52 | 176 | kprobes_inc_nmissed_count(p); |
42cc2060 | 177 | prepare_singlestep(p, regs); |
0dc036c9 | 178 | kcb->kprobe_status = KPROBE_REENTER; |
42cc2060 | 179 | return 1; |
1da177e4 | 180 | } else { |
eb3a7292 KA |
181 | if (*addr != BREAKPOINT_INSTRUCTION) { |
182 | /* If trap variant, then it belongs not to us */ | |
183 | kprobe_opcode_t cur_insn = *addr; | |
184 | if (is_trap(cur_insn)) | |
185 | goto no_kprobe; | |
186 | /* The breakpoint instruction was removed by | |
187 | * another cpu right after we hit, no further | |
188 | * handling of this interrupt is appropriate | |
189 | */ | |
190 | ret = 1; | |
191 | goto no_kprobe; | |
192 | } | |
0dc036c9 | 193 | p = __get_cpu_var(current_kprobe); |
1da177e4 LT |
194 | if (p->break_handler && p->break_handler(p, regs)) { |
195 | goto ss_probe; | |
196 | } | |
197 | } | |
1da177e4 LT |
198 | goto no_kprobe; |
199 | } | |
200 | ||
1da177e4 LT |
201 | p = get_kprobe(addr); |
202 | if (!p) { | |
1da177e4 LT |
203 | if (*addr != BREAKPOINT_INSTRUCTION) { |
204 | /* | |
205 | * PowerPC has multiple variants of the "trap" | |
206 | * instruction. If the current instruction is a | |
207 | * trap variant, it could belong to someone else | |
208 | */ | |
209 | kprobe_opcode_t cur_insn = *addr; | |
deac66ae | 210 | if (is_trap(cur_insn)) |
1da177e4 LT |
211 | goto no_kprobe; |
212 | /* | |
213 | * The breakpoint instruction was removed right | |
214 | * after we hit it. Another cpu has removed | |
215 | * either a probepoint or a debugger breakpoint | |
216 | * at this address. In either case, no further | |
217 | * handling of this interrupt is appropriate. | |
218 | */ | |
219 | ret = 1; | |
220 | } | |
221 | /* Not one of ours: let kernel handle it */ | |
222 | goto no_kprobe; | |
223 | } | |
224 | ||
0dc036c9 AM |
225 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; |
226 | set_current_kprobe(p, regs, kcb); | |
1da177e4 LT |
227 | if (p->pre_handler && p->pre_handler(p, regs)) |
228 | /* handler has already set things up, so skip ss setup */ | |
229 | return 1; | |
230 | ||
231 | ss_probe: | |
232 | prepare_singlestep(p, regs); | |
0dc036c9 | 233 | kcb->kprobe_status = KPROBE_HIT_SS; |
1da177e4 LT |
234 | return 1; |
235 | ||
236 | no_kprobe: | |
d217d545 | 237 | preempt_enable_no_resched(); |
1da177e4 LT |
238 | return ret; |
239 | } | |
240 | ||
97f7943d RL |
241 | /* |
242 | * Function return probe trampoline: | |
243 | * - init_kprobes() establishes a probepoint here | |
244 | * - When the probed function returns, this probe | |
245 | * causes the handlers to fire | |
246 | */ | |
247 | void kretprobe_trampoline_holder(void) | |
248 | { | |
249 | asm volatile(".global kretprobe_trampoline\n" | |
250 | "kretprobe_trampoline:\n" | |
251 | "nop\n"); | |
252 | } | |
253 | ||
254 | /* | |
255 | * Called when the probe at kretprobe trampoline is hit | |
256 | */ | |
bb144a85 | 257 | int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) |
97f7943d RL |
258 | { |
259 | struct kretprobe_instance *ri = NULL; | |
260 | struct hlist_head *head; | |
261 | struct hlist_node *node, *tmp; | |
991a51d8 | 262 | unsigned long flags, orig_ret_address = 0; |
97f7943d RL |
263 | unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline; |
264 | ||
991a51d8 | 265 | spin_lock_irqsave(&kretprobe_lock, flags); |
97f7943d RL |
266 | head = kretprobe_inst_table_head(current); |
267 | ||
268 | /* | |
269 | * It is possible to have multiple instances associated with a given | |
270 | * task either because an multiple functions in the call path | |
271 | * have a return probe installed on them, and/or more then one return | |
272 | * return probe was registered for a target function. | |
273 | * | |
274 | * We can handle this because: | |
275 | * - instances are always inserted at the head of the list | |
276 | * - when multiple return probes are registered for the same | |
277 | * function, the first instance's ret_addr will point to the | |
278 | * real return address, and all the rest will point to | |
279 | * kretprobe_trampoline | |
280 | */ | |
281 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { | |
282 | if (ri->task != current) | |
283 | /* another task is sharing our hash bucket */ | |
284 | continue; | |
285 | ||
286 | if (ri->rp && ri->rp->handler) | |
287 | ri->rp->handler(ri, regs); | |
288 | ||
289 | orig_ret_address = (unsigned long)ri->ret_addr; | |
290 | recycle_rp_inst(ri); | |
291 | ||
292 | if (orig_ret_address != trampoline_address) | |
293 | /* | |
294 | * This is the real return address. Any other | |
295 | * instances associated with this task are for | |
296 | * other calls deeper on the call stack | |
297 | */ | |
298 | break; | |
299 | } | |
300 | ||
301 | BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address)); | |
302 | regs->nip = orig_ret_address; | |
303 | ||
0dc036c9 | 304 | reset_current_kprobe(); |
991a51d8 | 305 | spin_unlock_irqrestore(&kretprobe_lock, flags); |
66ff2d06 | 306 | preempt_enable_no_resched(); |
97f7943d RL |
307 | |
308 | /* | |
309 | * By returning a non-zero value, we are telling | |
d217d545 AM |
310 | * kprobe_handler() that we don't want the post_handler |
311 | * to run (and have re-enabled preemption) | |
97f7943d RL |
312 | */ |
313 | return 1; | |
314 | } | |
315 | ||
1da177e4 LT |
316 | /* |
317 | * Called after single-stepping. p->addr is the address of the | |
318 | * instruction whose first byte has been replaced by the "breakpoint" | |
319 | * instruction. To avoid the SMP problems that can occur when we | |
320 | * temporarily put back the original opcode to single-step, we | |
321 | * single-stepped a copy of the instruction. The address of this | |
322 | * copy is p->ainsn.insn. | |
323 | */ | |
bb144a85 | 324 | static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
325 | { |
326 | int ret; | |
9ec4b1f3 | 327 | unsigned int insn = *p->ainsn.insn; |
1da177e4 LT |
328 | |
329 | regs->nip = (unsigned long)p->addr; | |
9ec4b1f3 | 330 | ret = emulate_step(regs, insn); |
1da177e4 LT |
331 | if (ret == 0) |
332 | regs->nip = (unsigned long)p->addr + 4; | |
1da177e4 LT |
333 | } |
334 | ||
335 | static inline int post_kprobe_handler(struct pt_regs *regs) | |
336 | { | |
0dc036c9 AM |
337 | struct kprobe *cur = kprobe_running(); |
338 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
339 | ||
340 | if (!cur) | |
1da177e4 LT |
341 | return 0; |
342 | ||
0dc036c9 AM |
343 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
344 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
345 | cur->post_handler(cur, regs, 0); | |
42cc2060 | 346 | } |
1da177e4 | 347 | |
0dc036c9 AM |
348 | resume_execution(cur, regs); |
349 | regs->msr |= kcb->kprobe_saved_msr; | |
1da177e4 | 350 | |
42cc2060 | 351 | /*Restore back the original saved kprobes variables and continue. */ |
0dc036c9 AM |
352 | if (kcb->kprobe_status == KPROBE_REENTER) { |
353 | restore_previous_kprobe(kcb); | |
42cc2060 PP |
354 | goto out; |
355 | } | |
0dc036c9 | 356 | reset_current_kprobe(); |
42cc2060 | 357 | out: |
1da177e4 LT |
358 | preempt_enable_no_resched(); |
359 | ||
360 | /* | |
361 | * if somebody else is singlestepping across a probe point, msr | |
362 | * will have SE set, in which case, continue the remaining processing | |
363 | * of do_debug, as if this is not a probe hit. | |
364 | */ | |
365 | if (regs->msr & MSR_SE) | |
366 | return 0; | |
367 | ||
368 | return 1; | |
369 | } | |
370 | ||
1da177e4 LT |
371 | static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
372 | { | |
0dc036c9 AM |
373 | struct kprobe *cur = kprobe_running(); |
374 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
375 | ||
376 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
1da177e4 LT |
377 | return 1; |
378 | ||
0dc036c9 AM |
379 | if (kcb->kprobe_status & KPROBE_HIT_SS) { |
380 | resume_execution(cur, regs); | |
f829fd23 | 381 | regs->msr &= ~MSR_SE; |
0dc036c9 | 382 | regs->msr |= kcb->kprobe_saved_msr; |
1da177e4 | 383 | |
0dc036c9 | 384 | reset_current_kprobe(); |
1da177e4 LT |
385 | preempt_enable_no_resched(); |
386 | } | |
387 | return 0; | |
388 | } | |
389 | ||
390 | /* | |
391 | * Wrapper routine to for handling exceptions. | |
392 | */ | |
bb144a85 PP |
393 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
394 | unsigned long val, void *data) | |
1da177e4 LT |
395 | { |
396 | struct die_args *args = (struct die_args *)data; | |
397 | int ret = NOTIFY_DONE; | |
398 | ||
1da177e4 | 399 | switch (val) { |
1da177e4 LT |
400 | case DIE_BPT: |
401 | if (kprobe_handler(args->regs)) | |
402 | ret = NOTIFY_STOP; | |
403 | break; | |
404 | case DIE_SSTEP: | |
405 | if (post_kprobe_handler(args->regs)) | |
406 | ret = NOTIFY_STOP; | |
407 | break; | |
1da177e4 | 408 | case DIE_PAGE_FAULT: |
d217d545 AM |
409 | /* kprobe_running() needs smp_processor_id() */ |
410 | preempt_disable(); | |
1da177e4 LT |
411 | if (kprobe_running() && |
412 | kprobe_fault_handler(args->regs, args->trapnr)) | |
413 | ret = NOTIFY_STOP; | |
d217d545 | 414 | preempt_enable(); |
1da177e4 LT |
415 | break; |
416 | default: | |
417 | break; | |
418 | } | |
1da177e4 LT |
419 | return ret; |
420 | } | |
421 | ||
bb144a85 | 422 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
423 | { |
424 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
0dc036c9 | 425 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 426 | |
0dc036c9 | 427 | memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs)); |
1da177e4 LT |
428 | |
429 | /* setup return addr to the jprobe handler routine */ | |
430 | regs->nip = (unsigned long)(((func_descr_t *)jp->entry)->entry); | |
431 | regs->gpr[2] = (unsigned long)(((func_descr_t *)jp->entry)->toc); | |
432 | ||
433 | return 1; | |
434 | } | |
435 | ||
bb144a85 | 436 | void __kprobes jprobe_return(void) |
1da177e4 LT |
437 | { |
438 | asm volatile("trap" ::: "memory"); | |
439 | } | |
440 | ||
bb144a85 | 441 | void __kprobes jprobe_return_end(void) |
1da177e4 LT |
442 | { |
443 | }; | |
444 | ||
bb144a85 | 445 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 446 | { |
0dc036c9 AM |
447 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
448 | ||
1da177e4 LT |
449 | /* |
450 | * FIXME - we should ideally be validating that we got here 'cos | |
451 | * of the "trap" in jprobe_return() above, before restoring the | |
452 | * saved regs... | |
453 | */ | |
0dc036c9 | 454 | memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs)); |
d217d545 | 455 | preempt_enable_no_resched(); |
1da177e4 LT |
456 | return 1; |
457 | } | |
97f7943d RL |
458 | |
459 | static struct kprobe trampoline_p = { | |
460 | .addr = (kprobe_opcode_t *) &kretprobe_trampoline, | |
461 | .pre_handler = trampoline_probe_handler | |
462 | }; | |
463 | ||
6772926b | 464 | int __init arch_init_kprobes(void) |
97f7943d RL |
465 | { |
466 | return register_kprobe(&trampoline_p); | |
467 | } |