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4ba069b8 MG |
1 | /* |
2 | * Kernel Probes (KProbes) | |
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, 2006 | |
19 | * | |
20 | * s390 port, used ppc64 as template. Mike Grundy <grundym@us.ibm.com> | |
21 | */ | |
22 | ||
23 | #include <linux/config.h> | |
24 | #include <linux/kprobes.h> | |
25 | #include <linux/ptrace.h> | |
26 | #include <linux/preempt.h> | |
27 | #include <linux/stop_machine.h> | |
28 | #include <asm/cacheflush.h> | |
29 | #include <asm/kdebug.h> | |
30 | #include <asm/sections.h> | |
31 | #include <asm/uaccess.h> | |
32 | #include <linux/module.h> | |
33 | ||
34 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; | |
35 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); | |
36 | ||
37 | int __kprobes arch_prepare_kprobe(struct kprobe *p) | |
38 | { | |
39 | /* Make sure the probe isn't going on a difficult instruction */ | |
40 | if (is_prohibited_opcode((kprobe_opcode_t *) p->addr)) | |
41 | return -EINVAL; | |
42 | ||
43 | if ((unsigned long)p->addr & 0x01) { | |
44 | printk("Attempt to register kprobe at an unaligned address\n"); | |
45 | return -EINVAL; | |
46 | } | |
47 | ||
48 | /* Use the get_insn_slot() facility for correctness */ | |
49 | if (!(p->ainsn.insn = get_insn_slot())) | |
50 | return -ENOMEM; | |
51 | ||
52 | memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); | |
53 | ||
54 | get_instruction_type(&p->ainsn); | |
55 | p->opcode = *p->addr; | |
56 | return 0; | |
57 | } | |
58 | ||
59 | int __kprobes is_prohibited_opcode(kprobe_opcode_t *instruction) | |
60 | { | |
61 | switch (*(__u8 *) instruction) { | |
62 | case 0x0c: /* bassm */ | |
63 | case 0x0b: /* bsm */ | |
64 | case 0x83: /* diag */ | |
65 | case 0x44: /* ex */ | |
66 | return -EINVAL; | |
67 | } | |
68 | switch (*(__u16 *) instruction) { | |
69 | case 0x0101: /* pr */ | |
70 | case 0xb25a: /* bsa */ | |
71 | case 0xb240: /* bakr */ | |
72 | case 0xb258: /* bsg */ | |
73 | case 0xb218: /* pc */ | |
74 | case 0xb228: /* pt */ | |
75 | return -EINVAL; | |
76 | } | |
77 | return 0; | |
78 | } | |
79 | ||
80 | void __kprobes get_instruction_type(struct arch_specific_insn *ainsn) | |
81 | { | |
82 | /* default fixup method */ | |
83 | ainsn->fixup = FIXUP_PSW_NORMAL; | |
84 | ||
85 | /* save r1 operand */ | |
86 | ainsn->reg = (*ainsn->insn & 0xf0) >> 4; | |
87 | ||
88 | /* save the instruction length (pop 5-5) in bytes */ | |
89 | switch (*(__u8 *) (ainsn->insn) >> 4) { | |
90 | case 0: | |
91 | ainsn->ilen = 2; | |
92 | break; | |
93 | case 1: | |
94 | case 2: | |
95 | ainsn->ilen = 4; | |
96 | break; | |
97 | case 3: | |
98 | ainsn->ilen = 6; | |
99 | break; | |
100 | } | |
101 | ||
102 | switch (*(__u8 *) ainsn->insn) { | |
103 | case 0x05: /* balr */ | |
104 | case 0x0d: /* basr */ | |
105 | ainsn->fixup = FIXUP_RETURN_REGISTER; | |
106 | /* if r2 = 0, no branch will be taken */ | |
107 | if ((*ainsn->insn & 0x0f) == 0) | |
108 | ainsn->fixup |= FIXUP_BRANCH_NOT_TAKEN; | |
109 | break; | |
110 | case 0x06: /* bctr */ | |
111 | case 0x07: /* bcr */ | |
112 | ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN; | |
113 | break; | |
114 | case 0x45: /* bal */ | |
115 | case 0x4d: /* bas */ | |
116 | ainsn->fixup = FIXUP_RETURN_REGISTER; | |
117 | break; | |
118 | case 0x47: /* bc */ | |
119 | case 0x46: /* bct */ | |
120 | case 0x86: /* bxh */ | |
121 | case 0x87: /* bxle */ | |
122 | ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN; | |
123 | break; | |
124 | case 0x82: /* lpsw */ | |
125 | ainsn->fixup = FIXUP_NOT_REQUIRED; | |
126 | break; | |
127 | case 0xb2: /* lpswe */ | |
128 | if (*(((__u8 *) ainsn->insn) + 1) == 0xb2) { | |
129 | ainsn->fixup = FIXUP_NOT_REQUIRED; | |
130 | } | |
131 | break; | |
132 | case 0xa7: /* bras */ | |
133 | if ((*ainsn->insn & 0x0f) == 0x05) { | |
134 | ainsn->fixup |= FIXUP_RETURN_REGISTER; | |
135 | } | |
136 | break; | |
137 | case 0xc0: | |
138 | if ((*ainsn->insn & 0x0f) == 0x00 /* larl */ | |
139 | || (*ainsn->insn & 0x0f) == 0x05) /* brasl */ | |
140 | ainsn->fixup |= FIXUP_RETURN_REGISTER; | |
141 | break; | |
142 | case 0xeb: | |
143 | if (*(((__u8 *) ainsn->insn) + 5 ) == 0x44 || /* bxhg */ | |
144 | *(((__u8 *) ainsn->insn) + 5) == 0x45) {/* bxleg */ | |
145 | ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN; | |
146 | } | |
147 | break; | |
148 | case 0xe3: /* bctg */ | |
149 | if (*(((__u8 *) ainsn->insn) + 5) == 0x46) { | |
150 | ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN; | |
151 | } | |
152 | break; | |
153 | } | |
154 | } | |
155 | ||
156 | static int __kprobes swap_instruction(void *aref) | |
157 | { | |
158 | struct ins_replace_args *args = aref; | |
159 | int err = -EFAULT; | |
160 | ||
161 | asm volatile( | |
162 | "0: mvc 0(2,%2),0(%3)\n" | |
163 | "1: la %0,0\n" | |
164 | "2:\n" | |
165 | EX_TABLE(0b,2b) | |
166 | : "+d" (err), "=m" (*args->ptr) | |
167 | : "a" (args->ptr), "a" (&args->new), "m" (args->new)); | |
168 | return err; | |
169 | } | |
170 | ||
171 | void __kprobes arch_arm_kprobe(struct kprobe *p) | |
172 | { | |
173 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
174 | unsigned long status = kcb->kprobe_status; | |
175 | struct ins_replace_args args; | |
176 | ||
177 | args.ptr = p->addr; | |
178 | args.old = p->opcode; | |
179 | args.new = BREAKPOINT_INSTRUCTION; | |
180 | ||
181 | kcb->kprobe_status = KPROBE_SWAP_INST; | |
182 | stop_machine_run(swap_instruction, &args, NR_CPUS); | |
183 | kcb->kprobe_status = status; | |
184 | } | |
185 | ||
186 | void __kprobes arch_disarm_kprobe(struct kprobe *p) | |
187 | { | |
188 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
189 | unsigned long status = kcb->kprobe_status; | |
190 | struct ins_replace_args args; | |
191 | ||
192 | args.ptr = p->addr; | |
193 | args.old = BREAKPOINT_INSTRUCTION; | |
194 | args.new = p->opcode; | |
195 | ||
196 | kcb->kprobe_status = KPROBE_SWAP_INST; | |
197 | stop_machine_run(swap_instruction, &args, NR_CPUS); | |
198 | kcb->kprobe_status = status; | |
199 | } | |
200 | ||
201 | void __kprobes arch_remove_kprobe(struct kprobe *p) | |
202 | { | |
203 | mutex_lock(&kprobe_mutex); | |
204 | free_insn_slot(p->ainsn.insn); | |
205 | mutex_unlock(&kprobe_mutex); | |
206 | } | |
207 | ||
208 | static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) | |
209 | { | |
210 | per_cr_bits kprobe_per_regs[1]; | |
211 | ||
212 | memset(kprobe_per_regs, 0, sizeof(per_cr_bits)); | |
213 | regs->psw.addr = (unsigned long)p->ainsn.insn | PSW_ADDR_AMODE; | |
214 | ||
215 | /* Set up the per control reg info, will pass to lctl */ | |
216 | kprobe_per_regs[0].em_instruction_fetch = 1; | |
217 | kprobe_per_regs[0].starting_addr = (unsigned long)p->ainsn.insn; | |
218 | kprobe_per_regs[0].ending_addr = (unsigned long)p->ainsn.insn + 1; | |
219 | ||
220 | /* Set the PER control regs, turns on single step for this address */ | |
221 | __ctl_load(kprobe_per_regs, 9, 11); | |
222 | regs->psw.mask |= PSW_MASK_PER; | |
223 | regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK); | |
224 | } | |
225 | ||
226 | static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) | |
227 | { | |
228 | kcb->prev_kprobe.kp = kprobe_running(); | |
229 | kcb->prev_kprobe.status = kcb->kprobe_status; | |
230 | kcb->prev_kprobe.kprobe_saved_imask = kcb->kprobe_saved_imask; | |
231 | memcpy(kcb->prev_kprobe.kprobe_saved_ctl, kcb->kprobe_saved_ctl, | |
232 | sizeof(kcb->kprobe_saved_ctl)); | |
233 | } | |
234 | ||
235 | static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) | |
236 | { | |
237 | __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; | |
238 | kcb->kprobe_status = kcb->prev_kprobe.status; | |
239 | kcb->kprobe_saved_imask = kcb->prev_kprobe.kprobe_saved_imask; | |
240 | memcpy(kcb->kprobe_saved_ctl, kcb->prev_kprobe.kprobe_saved_ctl, | |
241 | sizeof(kcb->kprobe_saved_ctl)); | |
242 | } | |
243 | ||
244 | static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, | |
245 | struct kprobe_ctlblk *kcb) | |
246 | { | |
247 | __get_cpu_var(current_kprobe) = p; | |
248 | /* Save the interrupt and per flags */ | |
249 | kcb->kprobe_saved_imask = regs->psw.mask & | |
250 | (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK); | |
251 | /* Save the control regs that govern PER */ | |
252 | __ctl_store(kcb->kprobe_saved_ctl, 9, 11); | |
253 | } | |
254 | ||
255 | /* Called with kretprobe_lock held */ | |
256 | void __kprobes arch_prepare_kretprobe(struct kretprobe *rp, | |
257 | struct pt_regs *regs) | |
258 | { | |
259 | struct kretprobe_instance *ri; | |
260 | ||
261 | if ((ri = get_free_rp_inst(rp)) != NULL) { | |
262 | ri->rp = rp; | |
263 | ri->task = current; | |
264 | ri->ret_addr = (kprobe_opcode_t *) regs->gprs[14]; | |
265 | ||
266 | /* Replace the return addr with trampoline addr */ | |
267 | regs->gprs[14] = (unsigned long)&kretprobe_trampoline; | |
268 | ||
269 | add_rp_inst(ri); | |
270 | } else { | |
271 | rp->nmissed++; | |
272 | } | |
273 | } | |
274 | ||
275 | static int __kprobes kprobe_handler(struct pt_regs *regs) | |
276 | { | |
277 | struct kprobe *p; | |
278 | int ret = 0; | |
279 | unsigned long *addr = (unsigned long *) | |
280 | ((regs->psw.addr & PSW_ADDR_INSN) - 2); | |
281 | struct kprobe_ctlblk *kcb; | |
282 | ||
283 | /* | |
284 | * We don't want to be preempted for the entire | |
285 | * duration of kprobe processing | |
286 | */ | |
287 | preempt_disable(); | |
288 | kcb = get_kprobe_ctlblk(); | |
289 | ||
290 | /* Check we're not actually recursing */ | |
291 | if (kprobe_running()) { | |
292 | p = get_kprobe(addr); | |
293 | if (p) { | |
294 | if (kcb->kprobe_status == KPROBE_HIT_SS && | |
295 | *p->ainsn.insn == BREAKPOINT_INSTRUCTION) { | |
296 | regs->psw.mask &= ~PSW_MASK_PER; | |
297 | regs->psw.mask |= kcb->kprobe_saved_imask; | |
298 | goto no_kprobe; | |
299 | } | |
300 | /* We have reentered the kprobe_handler(), since | |
301 | * another probe was hit while within the handler. | |
302 | * We here save the original kprobes variables and | |
303 | * just single step on the instruction of the new probe | |
304 | * without calling any user handlers. | |
305 | */ | |
306 | save_previous_kprobe(kcb); | |
307 | set_current_kprobe(p, regs, kcb); | |
308 | kprobes_inc_nmissed_count(p); | |
309 | prepare_singlestep(p, regs); | |
310 | kcb->kprobe_status = KPROBE_REENTER; | |
311 | return 1; | |
312 | } else { | |
313 | p = __get_cpu_var(current_kprobe); | |
314 | if (p->break_handler && p->break_handler(p, regs)) { | |
315 | goto ss_probe; | |
316 | } | |
317 | } | |
318 | goto no_kprobe; | |
319 | } | |
320 | ||
321 | p = get_kprobe(addr); | |
322 | if (!p) { | |
323 | if (*addr != BREAKPOINT_INSTRUCTION) { | |
324 | /* | |
325 | * The breakpoint instruction was removed right | |
326 | * after we hit it. Another cpu has removed | |
327 | * either a probepoint or a debugger breakpoint | |
328 | * at this address. In either case, no further | |
329 | * handling of this interrupt is appropriate. | |
330 | * | |
331 | */ | |
332 | ret = 1; | |
333 | } | |
334 | /* Not one of ours: let kernel handle it */ | |
335 | goto no_kprobe; | |
336 | } | |
337 | ||
338 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
339 | set_current_kprobe(p, regs, kcb); | |
340 | if (p->pre_handler && p->pre_handler(p, regs)) | |
341 | /* handler has already set things up, so skip ss setup */ | |
342 | return 1; | |
343 | ||
344 | ss_probe: | |
345 | prepare_singlestep(p, regs); | |
346 | kcb->kprobe_status = KPROBE_HIT_SS; | |
347 | return 1; | |
348 | ||
349 | no_kprobe: | |
350 | preempt_enable_no_resched(); | |
351 | return ret; | |
352 | } | |
353 | ||
354 | /* | |
355 | * Function return probe trampoline: | |
356 | * - init_kprobes() establishes a probepoint here | |
357 | * - When the probed function returns, this probe | |
358 | * causes the handlers to fire | |
359 | */ | |
360 | void __kprobes kretprobe_trampoline_holder(void) | |
361 | { | |
362 | asm volatile(".global kretprobe_trampoline\n" | |
363 | "kretprobe_trampoline: bcr 0,0\n"); | |
364 | } | |
365 | ||
366 | /* | |
367 | * Called when the probe at kretprobe trampoline is hit | |
368 | */ | |
369 | int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) | |
370 | { | |
371 | struct kretprobe_instance *ri = NULL; | |
99219a3f | 372 | struct hlist_head *head, empty_rp; |
4ba069b8 MG |
373 | struct hlist_node *node, *tmp; |
374 | unsigned long flags, orig_ret_address = 0; | |
375 | unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline; | |
376 | ||
99219a3f | 377 | INIT_HLIST_HEAD(&empty_rp); |
4ba069b8 MG |
378 | spin_lock_irqsave(&kretprobe_lock, flags); |
379 | head = kretprobe_inst_table_head(current); | |
380 | ||
381 | /* | |
382 | * It is possible to have multiple instances associated with a given | |
383 | * task either because an multiple functions in the call path | |
384 | * have a return probe installed on them, and/or more then one return | |
385 | * return probe was registered for a target function. | |
386 | * | |
387 | * We can handle this because: | |
388 | * - instances are always inserted at the head of the list | |
389 | * - when multiple return probes are registered for the same | |
390 | * function, the first instance's ret_addr will point to the | |
391 | * real return address, and all the rest will point to | |
392 | * kretprobe_trampoline | |
393 | */ | |
394 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { | |
395 | if (ri->task != current) | |
396 | /* another task is sharing our hash bucket */ | |
397 | continue; | |
398 | ||
399 | if (ri->rp && ri->rp->handler) | |
400 | ri->rp->handler(ri, regs); | |
401 | ||
402 | orig_ret_address = (unsigned long)ri->ret_addr; | |
99219a3f | 403 | recycle_rp_inst(ri, &empty_rp); |
4ba069b8 MG |
404 | |
405 | if (orig_ret_address != trampoline_address) { | |
406 | /* | |
407 | * This is the real return address. Any other | |
408 | * instances associated with this task are for | |
409 | * other calls deeper on the call stack | |
410 | */ | |
411 | break; | |
412 | } | |
413 | } | |
414 | BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address)); | |
415 | regs->psw.addr = orig_ret_address | PSW_ADDR_AMODE; | |
416 | ||
417 | reset_current_kprobe(); | |
418 | spin_unlock_irqrestore(&kretprobe_lock, flags); | |
419 | preempt_enable_no_resched(); | |
420 | ||
99219a3f | 421 | hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { |
422 | hlist_del(&ri->hlist); | |
423 | kfree(ri); | |
424 | } | |
4ba069b8 MG |
425 | /* |
426 | * By returning a non-zero value, we are telling | |
427 | * kprobe_handler() that we don't want the post_handler | |
428 | * to run (and have re-enabled preemption) | |
429 | */ | |
430 | return 1; | |
431 | } | |
432 | ||
433 | /* | |
434 | * Called after single-stepping. p->addr is the address of the | |
435 | * instruction whose first byte has been replaced by the "breakpoint" | |
436 | * instruction. To avoid the SMP problems that can occur when we | |
437 | * temporarily put back the original opcode to single-step, we | |
438 | * single-stepped a copy of the instruction. The address of this | |
439 | * copy is p->ainsn.insn. | |
440 | */ | |
441 | static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs) | |
442 | { | |
443 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
444 | ||
445 | regs->psw.addr &= PSW_ADDR_INSN; | |
446 | ||
447 | if (p->ainsn.fixup & FIXUP_PSW_NORMAL) | |
448 | regs->psw.addr = (unsigned long)p->addr + | |
449 | ((unsigned long)regs->psw.addr - | |
450 | (unsigned long)p->ainsn.insn); | |
451 | ||
452 | if (p->ainsn.fixup & FIXUP_BRANCH_NOT_TAKEN) | |
453 | if ((unsigned long)regs->psw.addr - | |
454 | (unsigned long)p->ainsn.insn == p->ainsn.ilen) | |
455 | regs->psw.addr = (unsigned long)p->addr + p->ainsn.ilen; | |
456 | ||
457 | if (p->ainsn.fixup & FIXUP_RETURN_REGISTER) | |
458 | regs->gprs[p->ainsn.reg] = ((unsigned long)p->addr + | |
459 | (regs->gprs[p->ainsn.reg] - | |
460 | (unsigned long)p->ainsn.insn)) | |
461 | | PSW_ADDR_AMODE; | |
462 | ||
463 | regs->psw.addr |= PSW_ADDR_AMODE; | |
464 | /* turn off PER mode */ | |
465 | regs->psw.mask &= ~PSW_MASK_PER; | |
466 | /* Restore the original per control regs */ | |
467 | __ctl_load(kcb->kprobe_saved_ctl, 9, 11); | |
468 | regs->psw.mask |= kcb->kprobe_saved_imask; | |
469 | } | |
470 | ||
471 | static int __kprobes post_kprobe_handler(struct pt_regs *regs) | |
472 | { | |
473 | struct kprobe *cur = kprobe_running(); | |
474 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
475 | ||
476 | if (!cur) | |
477 | return 0; | |
478 | ||
479 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { | |
480 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
481 | cur->post_handler(cur, regs, 0); | |
482 | } | |
483 | ||
484 | resume_execution(cur, regs); | |
485 | ||
486 | /*Restore back the original saved kprobes variables and continue. */ | |
487 | if (kcb->kprobe_status == KPROBE_REENTER) { | |
488 | restore_previous_kprobe(kcb); | |
489 | goto out; | |
490 | } | |
491 | reset_current_kprobe(); | |
492 | out: | |
493 | preempt_enable_no_resched(); | |
494 | ||
495 | /* | |
496 | * if somebody else is singlestepping across a probe point, psw mask | |
497 | * will have PER set, in which case, continue the remaining processing | |
498 | * of do_single_step, as if this is not a probe hit. | |
499 | */ | |
500 | if (regs->psw.mask & PSW_MASK_PER) { | |
501 | return 0; | |
502 | } | |
503 | ||
504 | return 1; | |
505 | } | |
506 | ||
507 | static int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) | |
508 | { | |
509 | struct kprobe *cur = kprobe_running(); | |
510 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
511 | const struct exception_table_entry *entry; | |
512 | ||
513 | switch(kcb->kprobe_status) { | |
514 | case KPROBE_SWAP_INST: | |
515 | /* We are here because the instruction replacement failed */ | |
516 | return 0; | |
517 | case KPROBE_HIT_SS: | |
518 | case KPROBE_REENTER: | |
519 | /* | |
520 | * We are here because the instruction being single | |
521 | * stepped caused a page fault. We reset the current | |
522 | * kprobe and the nip points back to the probe address | |
523 | * and allow the page fault handler to continue as a | |
524 | * normal page fault. | |
525 | */ | |
526 | regs->psw.addr = (unsigned long)cur->addr | PSW_ADDR_AMODE; | |
527 | regs->psw.mask &= ~PSW_MASK_PER; | |
528 | regs->psw.mask |= kcb->kprobe_saved_imask; | |
529 | if (kcb->kprobe_status == KPROBE_REENTER) | |
530 | restore_previous_kprobe(kcb); | |
531 | else | |
532 | reset_current_kprobe(); | |
533 | preempt_enable_no_resched(); | |
534 | break; | |
535 | case KPROBE_HIT_ACTIVE: | |
536 | case KPROBE_HIT_SSDONE: | |
537 | /* | |
538 | * We increment the nmissed count for accounting, | |
539 | * we can also use npre/npostfault count for accouting | |
540 | * these specific fault cases. | |
541 | */ | |
542 | kprobes_inc_nmissed_count(cur); | |
543 | ||
544 | /* | |
545 | * We come here because instructions in the pre/post | |
546 | * handler caused the page_fault, this could happen | |
547 | * if handler tries to access user space by | |
548 | * copy_from_user(), get_user() etc. Let the | |
549 | * user-specified handler try to fix it first. | |
550 | */ | |
551 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
552 | return 1; | |
553 | ||
554 | /* | |
555 | * In case the user-specified fault handler returned | |
556 | * zero, try to fix up. | |
557 | */ | |
558 | entry = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN); | |
559 | if (entry) { | |
560 | regs->psw.addr = entry->fixup | PSW_ADDR_AMODE; | |
561 | return 1; | |
562 | } | |
563 | ||
564 | /* | |
565 | * fixup_exception() could not handle it, | |
566 | * Let do_page_fault() fix it. | |
567 | */ | |
568 | break; | |
569 | default: | |
570 | break; | |
571 | } | |
572 | return 0; | |
573 | } | |
574 | ||
575 | /* | |
576 | * Wrapper routine to for handling exceptions. | |
577 | */ | |
578 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, | |
579 | unsigned long val, void *data) | |
580 | { | |
581 | struct die_args *args = (struct die_args *)data; | |
582 | int ret = NOTIFY_DONE; | |
583 | ||
584 | switch (val) { | |
585 | case DIE_BPT: | |
586 | if (kprobe_handler(args->regs)) | |
587 | ret = NOTIFY_STOP; | |
588 | break; | |
589 | case DIE_SSTEP: | |
590 | if (post_kprobe_handler(args->regs)) | |
591 | ret = NOTIFY_STOP; | |
592 | break; | |
593 | case DIE_TRAP: | |
594 | case DIE_PAGE_FAULT: | |
595 | /* kprobe_running() needs smp_processor_id() */ | |
596 | preempt_disable(); | |
597 | if (kprobe_running() && | |
598 | kprobe_fault_handler(args->regs, args->trapnr)) | |
599 | ret = NOTIFY_STOP; | |
600 | preempt_enable(); | |
601 | break; | |
602 | default: | |
603 | break; | |
604 | } | |
605 | return ret; | |
606 | } | |
607 | ||
608 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) | |
609 | { | |
610 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
611 | unsigned long addr; | |
612 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
613 | ||
614 | memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs)); | |
615 | ||
616 | /* setup return addr to the jprobe handler routine */ | |
617 | regs->psw.addr = (unsigned long)(jp->entry) | PSW_ADDR_AMODE; | |
618 | ||
619 | /* r14 is the function return address */ | |
620 | kcb->jprobe_saved_r14 = (unsigned long)regs->gprs[14]; | |
621 | /* r15 is the stack pointer */ | |
622 | kcb->jprobe_saved_r15 = (unsigned long)regs->gprs[15]; | |
623 | addr = (unsigned long)kcb->jprobe_saved_r15; | |
624 | ||
625 | memcpy(kcb->jprobes_stack, (kprobe_opcode_t *) addr, | |
626 | MIN_STACK_SIZE(addr)); | |
627 | return 1; | |
628 | } | |
629 | ||
630 | void __kprobes jprobe_return(void) | |
631 | { | |
632 | asm volatile(".word 0x0002"); | |
633 | } | |
634 | ||
635 | void __kprobes jprobe_return_end(void) | |
636 | { | |
637 | asm volatile("bcr 0,0"); | |
638 | } | |
639 | ||
640 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) | |
641 | { | |
642 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
643 | unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_r15); | |
644 | ||
645 | /* Put the regs back */ | |
646 | memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs)); | |
647 | /* put the stack back */ | |
648 | memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack, | |
649 | MIN_STACK_SIZE(stack_addr)); | |
650 | preempt_enable_no_resched(); | |
651 | return 1; | |
652 | } | |
653 | ||
654 | static struct kprobe trampoline_p = { | |
655 | .addr = (kprobe_opcode_t *) & kretprobe_trampoline, | |
656 | .pre_handler = trampoline_probe_handler | |
657 | }; | |
658 | ||
659 | int __init arch_init_kprobes(void) | |
660 | { | |
661 | return register_kprobe(&trampoline_p); | |
662 | } |