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/kprobes.h>
24 #include <linux/ptrace.h>
25 #include <linux/preempt.h>
26 #include <linux/stop_machine.h>
27 #include <linux/kdebug.h>
28 #include <asm/cacheflush.h>
29 #include <asm/sections.h>
30 #include <asm/uaccess.h>
31 #include <linux/module.h>
32
33 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
34 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
35
36 struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
37
arch_prepare_kprobe(struct kprobe * p)38 int __kprobes arch_prepare_kprobe(struct kprobe *p)
39 {
40 /* Make sure the probe isn't going on a difficult instruction */
41 if (is_prohibited_opcode((kprobe_opcode_t *) p->addr))
42 return -EINVAL;
43
44 if ((unsigned long)p->addr & 0x01)
45 return -EINVAL;
46
47 /* Use the get_insn_slot() facility for correctness */
48 if (!(p->ainsn.insn = get_insn_slot()))
49 return -ENOMEM;
50
51 memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
52
53 get_instruction_type(&p->ainsn);
54 p->opcode = *p->addr;
55 return 0;
56 }
57
is_prohibited_opcode(kprobe_opcode_t * instruction)58 int __kprobes is_prohibited_opcode(kprobe_opcode_t *instruction)
59 {
60 switch (*(__u8 *) instruction) {
61 case 0x0c: /* bassm */
62 case 0x0b: /* bsm */
63 case 0x83: /* diag */
64 case 0x44: /* ex */
65 return -EINVAL;
66 }
67 switch (*(__u16 *) instruction) {
68 case 0x0101: /* pr */
69 case 0xb25a: /* bsa */
70 case 0xb240: /* bakr */
71 case 0xb258: /* bsg */
72 case 0xb218: /* pc */
73 case 0xb228: /* pt */
74 return -EINVAL;
75 }
76 return 0;
77 }
78
get_instruction_type(struct arch_specific_insn * ainsn)79 void __kprobes get_instruction_type(struct arch_specific_insn *ainsn)
80 {
81 /* default fixup method */
82 ainsn->fixup = FIXUP_PSW_NORMAL;
83
84 /* save r1 operand */
85 ainsn->reg = (*ainsn->insn & 0xf0) >> 4;
86
87 /* save the instruction length (pop 5-5) in bytes */
88 switch (*(__u8 *) (ainsn->insn) >> 6) {
89 case 0:
90 ainsn->ilen = 2;
91 break;
92 case 1:
93 case 2:
94 ainsn->ilen = 4;
95 break;
96 case 3:
97 ainsn->ilen = 6;
98 break;
99 }
100
101 switch (*(__u8 *) ainsn->insn) {
102 case 0x05: /* balr */
103 case 0x0d: /* basr */
104 ainsn->fixup = FIXUP_RETURN_REGISTER;
105 /* if r2 = 0, no branch will be taken */
106 if ((*ainsn->insn & 0x0f) == 0)
107 ainsn->fixup |= FIXUP_BRANCH_NOT_TAKEN;
108 break;
109 case 0x06: /* bctr */
110 case 0x07: /* bcr */
111 ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
112 break;
113 case 0x45: /* bal */
114 case 0x4d: /* bas */
115 ainsn->fixup = FIXUP_RETURN_REGISTER;
116 break;
117 case 0x47: /* bc */
118 case 0x46: /* bct */
119 case 0x86: /* bxh */
120 case 0x87: /* bxle */
121 ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
122 break;
123 case 0x82: /* lpsw */
124 ainsn->fixup = FIXUP_NOT_REQUIRED;
125 break;
126 case 0xb2: /* lpswe */
127 if (*(((__u8 *) ainsn->insn) + 1) == 0xb2) {
128 ainsn->fixup = FIXUP_NOT_REQUIRED;
129 }
130 break;
131 case 0xa7: /* bras */
132 if ((*ainsn->insn & 0x0f) == 0x05) {
133 ainsn->fixup |= FIXUP_RETURN_REGISTER;
134 }
135 break;
136 case 0xc0:
137 if ((*ainsn->insn & 0x0f) == 0x00 /* larl */
138 || (*ainsn->insn & 0x0f) == 0x05) /* brasl */
139 ainsn->fixup |= FIXUP_RETURN_REGISTER;
140 break;
141 case 0xeb:
142 if (*(((__u8 *) ainsn->insn) + 5 ) == 0x44 || /* bxhg */
143 *(((__u8 *) ainsn->insn) + 5) == 0x45) {/* bxleg */
144 ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
145 }
146 break;
147 case 0xe3: /* bctg */
148 if (*(((__u8 *) ainsn->insn) + 5) == 0x46) {
149 ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
150 }
151 break;
152 }
153 }
154
swap_instruction(void * aref)155 static int __kprobes swap_instruction(void *aref)
156 {
157 struct ins_replace_args *args = aref;
158 u32 *addr;
159 u32 instr;
160 int err = -EFAULT;
161
162 /*
163 * Text segment is read-only, hence we use stura to bypass dynamic
164 * address translation to exchange the instruction. Since stura
165 * always operates on four bytes, but we only want to exchange two
166 * bytes do some calculations to get things right. In addition we
167 * shall not cross any page boundaries (vmalloc area!) when writing
168 * the new instruction.
169 */
170 addr = (u32 *)((unsigned long)args->ptr & -4UL);
171 if ((unsigned long)args->ptr & 2)
172 instr = ((*addr) & 0xffff0000) | args->new;
173 else
174 instr = ((*addr) & 0x0000ffff) | args->new << 16;
175
176 asm volatile(
177 " lra %1,0(%1)\n"
178 "0: stura %2,%1\n"
179 "1: la %0,0\n"
180 "2:\n"
181 EX_TABLE(0b,2b)
182 : "+d" (err)
183 : "a" (addr), "d" (instr)
184 : "memory", "cc");
185
186 return err;
187 }
188
arch_arm_kprobe(struct kprobe * p)189 void __kprobes arch_arm_kprobe(struct kprobe *p)
190 {
191 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
192 unsigned long status = kcb->kprobe_status;
193 struct ins_replace_args args;
194
195 args.ptr = p->addr;
196 args.old = p->opcode;
197 args.new = BREAKPOINT_INSTRUCTION;
198
199 kcb->kprobe_status = KPROBE_SWAP_INST;
200 stop_machine(swap_instruction, &args, NULL);
201 kcb->kprobe_status = status;
202 }
203
arch_disarm_kprobe(struct kprobe * p)204 void __kprobes arch_disarm_kprobe(struct kprobe *p)
205 {
206 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
207 unsigned long status = kcb->kprobe_status;
208 struct ins_replace_args args;
209
210 args.ptr = p->addr;
211 args.old = BREAKPOINT_INSTRUCTION;
212 args.new = p->opcode;
213
214 kcb->kprobe_status = KPROBE_SWAP_INST;
215 stop_machine(swap_instruction, &args, NULL);
216 kcb->kprobe_status = status;
217 }
218
arch_remove_kprobe(struct kprobe * p)219 void __kprobes arch_remove_kprobe(struct kprobe *p)
220 {
221 if (p->ainsn.insn) {
222 free_insn_slot(p->ainsn.insn, 0);
223 p->ainsn.insn = NULL;
224 }
225 }
226
prepare_singlestep(struct kprobe * p,struct pt_regs * regs)227 static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
228 {
229 per_cr_bits kprobe_per_regs[1];
230
231 memset(kprobe_per_regs, 0, sizeof(per_cr_bits));
232 regs->psw.addr = (unsigned long)p->ainsn.insn | PSW_ADDR_AMODE;
233
234 /* Set up the per control reg info, will pass to lctl */
235 kprobe_per_regs[0].em_instruction_fetch = 1;
236 kprobe_per_regs[0].starting_addr = (unsigned long)p->ainsn.insn;
237 kprobe_per_regs[0].ending_addr = (unsigned long)p->ainsn.insn + 1;
238
239 /* Set the PER control regs, turns on single step for this address */
240 __ctl_load(kprobe_per_regs, 9, 11);
241 regs->psw.mask |= PSW_MASK_PER;
242 regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK);
243 }
244
save_previous_kprobe(struct kprobe_ctlblk * kcb)245 static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
246 {
247 kcb->prev_kprobe.kp = kprobe_running();
248 kcb->prev_kprobe.status = kcb->kprobe_status;
249 kcb->prev_kprobe.kprobe_saved_imask = kcb->kprobe_saved_imask;
250 memcpy(kcb->prev_kprobe.kprobe_saved_ctl, kcb->kprobe_saved_ctl,
251 sizeof(kcb->kprobe_saved_ctl));
252 }
253
restore_previous_kprobe(struct kprobe_ctlblk * kcb)254 static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
255 {
256 __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
257 kcb->kprobe_status = kcb->prev_kprobe.status;
258 kcb->kprobe_saved_imask = kcb->prev_kprobe.kprobe_saved_imask;
259 memcpy(kcb->kprobe_saved_ctl, kcb->prev_kprobe.kprobe_saved_ctl,
260 sizeof(kcb->kprobe_saved_ctl));
261 }
262
set_current_kprobe(struct kprobe * p,struct pt_regs * regs,struct kprobe_ctlblk * kcb)263 static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
264 struct kprobe_ctlblk *kcb)
265 {
266 __get_cpu_var(current_kprobe) = p;
267 /* Save the interrupt and per flags */
268 kcb->kprobe_saved_imask = regs->psw.mask &
269 (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK);
270 /* Save the control regs that govern PER */
271 __ctl_store(kcb->kprobe_saved_ctl, 9, 11);
272 }
273
arch_prepare_kretprobe(struct kretprobe_instance * ri,struct pt_regs * regs)274 void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
275 struct pt_regs *regs)
276 {
277 ri->ret_addr = (kprobe_opcode_t *) regs->gprs[14];
278
279 /* Replace the return addr with trampoline addr */
280 regs->gprs[14] = (unsigned long)&kretprobe_trampoline;
281 }
282
kprobe_handler(struct pt_regs * regs)283 static int __kprobes kprobe_handler(struct pt_regs *regs)
284 {
285 struct kprobe *p;
286 int ret = 0;
287 unsigned long *addr = (unsigned long *)
288 ((regs->psw.addr & PSW_ADDR_INSN) - 2);
289 struct kprobe_ctlblk *kcb;
290
291 /*
292 * We don't want to be preempted for the entire
293 * duration of kprobe processing
294 */
295 preempt_disable();
296 kcb = get_kprobe_ctlblk();
297
298 /* Check we're not actually recursing */
299 if (kprobe_running()) {
300 p = get_kprobe(addr);
301 if (p) {
302 if (kcb->kprobe_status == KPROBE_HIT_SS &&
303 *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
304 regs->psw.mask &= ~PSW_MASK_PER;
305 regs->psw.mask |= kcb->kprobe_saved_imask;
306 goto no_kprobe;
307 }
308 /* We have reentered the kprobe_handler(), since
309 * another probe was hit while within the handler.
310 * We here save the original kprobes variables and
311 * just single step on the instruction of the new probe
312 * without calling any user handlers.
313 */
314 save_previous_kprobe(kcb);
315 set_current_kprobe(p, regs, kcb);
316 kprobes_inc_nmissed_count(p);
317 prepare_singlestep(p, regs);
318 kcb->kprobe_status = KPROBE_REENTER;
319 return 1;
320 } else {
321 p = __get_cpu_var(current_kprobe);
322 if (p->break_handler && p->break_handler(p, regs)) {
323 goto ss_probe;
324 }
325 }
326 goto no_kprobe;
327 }
328
329 p = get_kprobe(addr);
330 if (!p)
331 /*
332 * No kprobe at this address. The fault has not been
333 * caused by a kprobe breakpoint. The race of breakpoint
334 * vs. kprobe remove does not exist because on s390 we
335 * use stop_machine to arm/disarm the breakpoints.
336 */
337 goto no_kprobe;
338
339 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
340 set_current_kprobe(p, regs, kcb);
341 if (p->pre_handler && p->pre_handler(p, regs))
342 /* handler has already set things up, so skip ss setup */
343 return 1;
344
345 ss_probe:
346 prepare_singlestep(p, regs);
347 kcb->kprobe_status = KPROBE_HIT_SS;
348 return 1;
349
350 no_kprobe:
351 preempt_enable_no_resched();
352 return ret;
353 }
354
355 /*
356 * Function return probe trampoline:
357 * - init_kprobes() establishes a probepoint here
358 * - When the probed function returns, this probe
359 * causes the handlers to fire
360 */
kretprobe_trampoline_holder(void)361 static void __used kretprobe_trampoline_holder(void)
362 {
363 asm volatile(".global kretprobe_trampoline\n"
364 "kretprobe_trampoline: bcr 0,0\n");
365 }
366
367 /*
368 * Called when the probe at kretprobe trampoline is hit
369 */
trampoline_probe_handler(struct kprobe * p,struct pt_regs * regs)370 static int __kprobes trampoline_probe_handler(struct kprobe *p,
371 struct pt_regs *regs)
372 {
373 struct kretprobe_instance *ri = NULL;
374 struct hlist_head *head, empty_rp;
375 struct hlist_node *node, *tmp;
376 unsigned long flags, orig_ret_address = 0;
377 unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
378
379 INIT_HLIST_HEAD(&empty_rp);
380 kretprobe_hash_lock(current, &head, &flags);
381
382 /*
383 * It is possible to have multiple instances associated with a given
384 * task either because an multiple functions in the call path
385 * have a return probe installed on them, and/or more than one return
386 * return probe was registered for a target function.
387 *
388 * We can handle this because:
389 * - instances are always inserted at the head of the list
390 * - when multiple return probes are registered for the same
391 * function, the first instance's ret_addr will point to the
392 * real return address, and all the rest will point to
393 * kretprobe_trampoline
394 */
395 hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
396 if (ri->task != current)
397 /* another task is sharing our hash bucket */
398 continue;
399
400 if (ri->rp && ri->rp->handler)
401 ri->rp->handler(ri, regs);
402
403 orig_ret_address = (unsigned long)ri->ret_addr;
404 recycle_rp_inst(ri, &empty_rp);
405
406 if (orig_ret_address != trampoline_address) {
407 /*
408 * This is the real return address. Any other
409 * instances associated with this task are for
410 * other calls deeper on the call stack
411 */
412 break;
413 }
414 }
415 kretprobe_assert(ri, orig_ret_address, trampoline_address);
416 regs->psw.addr = orig_ret_address | PSW_ADDR_AMODE;
417
418 reset_current_kprobe();
419 kretprobe_hash_unlock(current, &flags);
420 preempt_enable_no_resched();
421
422 hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
423 hlist_del(&ri->hlist);
424 kfree(ri);
425 }
426 /*
427 * By returning a non-zero value, we are telling
428 * kprobe_handler() that we don't want the post_handler
429 * to run (and have re-enabled preemption)
430 */
431 return 1;
432 }
433
434 /*
435 * Called after single-stepping. p->addr is the address of the
436 * instruction whose first byte has been replaced by the "breakpoint"
437 * instruction. To avoid the SMP problems that can occur when we
438 * temporarily put back the original opcode to single-step, we
439 * single-stepped a copy of the instruction. The address of this
440 * copy is p->ainsn.insn.
441 */
resume_execution(struct kprobe * p,struct pt_regs * regs)442 static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
443 {
444 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
445
446 regs->psw.addr &= PSW_ADDR_INSN;
447
448 if (p->ainsn.fixup & FIXUP_PSW_NORMAL)
449 regs->psw.addr = (unsigned long)p->addr +
450 ((unsigned long)regs->psw.addr -
451 (unsigned long)p->ainsn.insn);
452
453 if (p->ainsn.fixup & FIXUP_BRANCH_NOT_TAKEN)
454 if ((unsigned long)regs->psw.addr -
455 (unsigned long)p->ainsn.insn == p->ainsn.ilen)
456 regs->psw.addr = (unsigned long)p->addr + p->ainsn.ilen;
457
458 if (p->ainsn.fixup & FIXUP_RETURN_REGISTER)
459 regs->gprs[p->ainsn.reg] = ((unsigned long)p->addr +
460 (regs->gprs[p->ainsn.reg] -
461 (unsigned long)p->ainsn.insn))
462 | PSW_ADDR_AMODE;
463
464 regs->psw.addr |= PSW_ADDR_AMODE;
465 /* turn off PER mode */
466 regs->psw.mask &= ~PSW_MASK_PER;
467 /* Restore the original per control regs */
468 __ctl_load(kcb->kprobe_saved_ctl, 9, 11);
469 regs->psw.mask |= kcb->kprobe_saved_imask;
470 }
471
post_kprobe_handler(struct pt_regs * regs)472 static int __kprobes post_kprobe_handler(struct pt_regs *regs)
473 {
474 struct kprobe *cur = kprobe_running();
475 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
476
477 if (!cur)
478 return 0;
479
480 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
481 kcb->kprobe_status = KPROBE_HIT_SSDONE;
482 cur->post_handler(cur, regs, 0);
483 }
484
485 resume_execution(cur, regs);
486
487 /*Restore back the original saved kprobes variables and continue. */
488 if (kcb->kprobe_status == KPROBE_REENTER) {
489 restore_previous_kprobe(kcb);
490 goto out;
491 }
492 reset_current_kprobe();
493 out:
494 preempt_enable_no_resched();
495
496 /*
497 * if somebody else is singlestepping across a probe point, psw mask
498 * will have PER set, in which case, continue the remaining processing
499 * of do_single_step, as if this is not a probe hit.
500 */
501 if (regs->psw.mask & PSW_MASK_PER) {
502 return 0;
503 }
504
505 return 1;
506 }
507
kprobe_fault_handler(struct pt_regs * regs,int trapnr)508 int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
509 {
510 struct kprobe *cur = kprobe_running();
511 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
512 const struct exception_table_entry *entry;
513
514 switch(kcb->kprobe_status) {
515 case KPROBE_SWAP_INST:
516 /* We are here because the instruction replacement failed */
517 return 0;
518 case KPROBE_HIT_SS:
519 case KPROBE_REENTER:
520 /*
521 * We are here because the instruction being single
522 * stepped caused a page fault. We reset the current
523 * kprobe and the nip points back to the probe address
524 * and allow the page fault handler to continue as a
525 * normal page fault.
526 */
527 regs->psw.addr = (unsigned long)cur->addr | PSW_ADDR_AMODE;
528 regs->psw.mask &= ~PSW_MASK_PER;
529 regs->psw.mask |= kcb->kprobe_saved_imask;
530 if (kcb->kprobe_status == KPROBE_REENTER)
531 restore_previous_kprobe(kcb);
532 else
533 reset_current_kprobe();
534 preempt_enable_no_resched();
535 break;
536 case KPROBE_HIT_ACTIVE:
537 case KPROBE_HIT_SSDONE:
538 /*
539 * We increment the nmissed count for accounting,
540 * we can also use npre/npostfault count for accouting
541 * these specific fault cases.
542 */
543 kprobes_inc_nmissed_count(cur);
544
545 /*
546 * We come here because instructions in the pre/post
547 * handler caused the page_fault, this could happen
548 * if handler tries to access user space by
549 * copy_from_user(), get_user() etc. Let the
550 * user-specified handler try to fix it first.
551 */
552 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
553 return 1;
554
555 /*
556 * In case the user-specified fault handler returned
557 * zero, try to fix up.
558 */
559 entry = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
560 if (entry) {
561 regs->psw.addr = entry->fixup | PSW_ADDR_AMODE;
562 return 1;
563 }
564
565 /*
566 * fixup_exception() could not handle it,
567 * Let do_page_fault() fix it.
568 */
569 break;
570 default:
571 break;
572 }
573 return 0;
574 }
575
576 /*
577 * Wrapper routine to for handling exceptions.
578 */
kprobe_exceptions_notify(struct notifier_block * self,unsigned long val,void * data)579 int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
580 unsigned long val, void *data)
581 {
582 struct die_args *args = (struct die_args *)data;
583 int ret = NOTIFY_DONE;
584
585 switch (val) {
586 case DIE_BPT:
587 if (kprobe_handler(args->regs))
588 ret = NOTIFY_STOP;
589 break;
590 case DIE_SSTEP:
591 if (post_kprobe_handler(args->regs))
592 ret = NOTIFY_STOP;
593 break;
594 case DIE_TRAP:
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
setjmp_pre_handler(struct kprobe * p,struct pt_regs * regs)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
jprobe_return(void)630 void __kprobes jprobe_return(void)
631 {
632 asm volatile(".word 0x0002");
633 }
634
jprobe_return_end(void)635 void __kprobes jprobe_return_end(void)
636 {
637 asm volatile("bcr 0,0");
638 }
639
longjmp_break_handler(struct kprobe * p,struct pt_regs * regs)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
arch_init_kprobes(void)659 int __init arch_init_kprobes(void)
660 {
661 return register_kprobe(&trampoline_p);
662 }
663
arch_trampoline_kprobe(struct kprobe * p)664 int __kprobes arch_trampoline_kprobe(struct kprobe *p)
665 {
666 if (p->addr == (kprobe_opcode_t *) & kretprobe_trampoline)
667 return 1;
668 return 0;
669 }
670