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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 <linux/uaccess.h>
29#include <linux/module.h>
30#include <linux/slab.h>
31#include <linux/hardirq.h>
32#include <linux/ftrace.h>
33#include <asm/cacheflush.h>
34#include <asm/sections.h>
35#include <asm/dis.h>
36
37DEFINE_PER_CPU(struct kprobe *, current_kprobe);
38DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
39
40struct kretprobe_blackpoint kretprobe_blacklist[] = { };
41
42DEFINE_INSN_CACHE_OPS(dmainsn);
43
44static void *alloc_dmainsn_page(void)
45{
46 return (void *)__get_free_page(GFP_KERNEL | GFP_DMA);
47}
48
49static void free_dmainsn_page(void *page)
50{
51 free_page((unsigned long)page);
52}
53
54struct kprobe_insn_cache kprobe_dmainsn_slots = {
55 .mutex = __MUTEX_INITIALIZER(kprobe_dmainsn_slots.mutex),
56 .alloc = alloc_dmainsn_page,
57 .free = free_dmainsn_page,
58 .pages = LIST_HEAD_INIT(kprobe_dmainsn_slots.pages),
59 .insn_size = MAX_INSN_SIZE,
60};
61
62static void copy_instruction(struct kprobe *p)
63{
64 unsigned long ip = (unsigned long) p->addr;
65 s64 disp, new_disp;
66 u64 addr, new_addr;
67
68 if (ftrace_location(ip) == ip) {
69
70
71
72
73
74
75 ftrace_generate_nop_insn((struct ftrace_insn *)p->ainsn.insn);
76 p->ainsn.is_ftrace_insn = 1;
77 } else
78 memcpy(p->ainsn.insn, p->addr, insn_length(*p->addr >> 8));
79 p->opcode = p->ainsn.insn[0];
80 if (!probe_is_insn_relative_long(p->ainsn.insn))
81 return;
82
83
84
85
86
87
88
89 disp = *(s32 *)&p->ainsn.insn[1];
90 addr = (u64)(unsigned long)p->addr;
91 new_addr = (u64)(unsigned long)p->ainsn.insn;
92 new_disp = ((addr + (disp * 2)) - new_addr) / 2;
93 *(s32 *)&p->ainsn.insn[1] = new_disp;
94}
95NOKPROBE_SYMBOL(copy_instruction);
96
97static inline int is_kernel_addr(void *addr)
98{
99 return addr < (void *)_end;
100}
101
102static int s390_get_insn_slot(struct kprobe *p)
103{
104
105
106
107
108
109 p->ainsn.insn = NULL;
110 if (is_kernel_addr(p->addr))
111 p->ainsn.insn = get_dmainsn_slot();
112 else if (is_module_addr(p->addr))
113 p->ainsn.insn = get_insn_slot();
114 return p->ainsn.insn ? 0 : -ENOMEM;
115}
116NOKPROBE_SYMBOL(s390_get_insn_slot);
117
118static void s390_free_insn_slot(struct kprobe *p)
119{
120 if (!p->ainsn.insn)
121 return;
122 if (is_kernel_addr(p->addr))
123 free_dmainsn_slot(p->ainsn.insn, 0);
124 else
125 free_insn_slot(p->ainsn.insn, 0);
126 p->ainsn.insn = NULL;
127}
128NOKPROBE_SYMBOL(s390_free_insn_slot);
129
130int arch_prepare_kprobe(struct kprobe *p)
131{
132 if ((unsigned long) p->addr & 0x01)
133 return -EINVAL;
134
135 if (probe_is_prohibited_opcode(p->addr))
136 return -EINVAL;
137 if (s390_get_insn_slot(p))
138 return -ENOMEM;
139 copy_instruction(p);
140 return 0;
141}
142NOKPROBE_SYMBOL(arch_prepare_kprobe);
143
144int arch_check_ftrace_location(struct kprobe *p)
145{
146 return 0;
147}
148
149struct swap_insn_args {
150 struct kprobe *p;
151 unsigned int arm_kprobe : 1;
152};
153
154static int swap_instruction(void *data)
155{
156 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
157 unsigned long status = kcb->kprobe_status;
158 struct swap_insn_args *args = data;
159 struct ftrace_insn new_insn, *insn;
160 struct kprobe *p = args->p;
161 size_t len;
162
163 new_insn.opc = args->arm_kprobe ? BREAKPOINT_INSTRUCTION : p->opcode;
164 len = sizeof(new_insn.opc);
165 if (!p->ainsn.is_ftrace_insn)
166 goto skip_ftrace;
167 len = sizeof(new_insn);
168 insn = (struct ftrace_insn *) p->addr;
169 if (args->arm_kprobe) {
170 if (is_ftrace_nop(insn))
171 new_insn.disp = KPROBE_ON_FTRACE_NOP;
172 else
173 new_insn.disp = KPROBE_ON_FTRACE_CALL;
174 } else {
175 ftrace_generate_call_insn(&new_insn, (unsigned long)p->addr);
176 if (insn->disp == KPROBE_ON_FTRACE_NOP)
177 ftrace_generate_nop_insn(&new_insn);
178 }
179skip_ftrace:
180 kcb->kprobe_status = KPROBE_SWAP_INST;
181 s390_kernel_write(p->addr, &new_insn, len);
182 kcb->kprobe_status = status;
183 return 0;
184}
185NOKPROBE_SYMBOL(swap_instruction);
186
187void arch_arm_kprobe(struct kprobe *p)
188{
189 struct swap_insn_args args = {.p = p, .arm_kprobe = 1};
190
191 stop_machine(swap_instruction, &args, NULL);
192}
193NOKPROBE_SYMBOL(arch_arm_kprobe);
194
195void arch_disarm_kprobe(struct kprobe *p)
196{
197 struct swap_insn_args args = {.p = p, .arm_kprobe = 0};
198
199 stop_machine(swap_instruction, &args, NULL);
200}
201NOKPROBE_SYMBOL(arch_disarm_kprobe);
202
203void arch_remove_kprobe(struct kprobe *p)
204{
205 s390_free_insn_slot(p);
206}
207NOKPROBE_SYMBOL(arch_remove_kprobe);
208
209static void enable_singlestep(struct kprobe_ctlblk *kcb,
210 struct pt_regs *regs,
211 unsigned long ip)
212{
213 struct per_regs per_kprobe;
214
215
216 per_kprobe.control = PER_EVENT_IFETCH;
217 per_kprobe.start = ip;
218 per_kprobe.end = ip;
219
220
221 __ctl_store(kcb->kprobe_saved_ctl, 9, 11);
222 kcb->kprobe_saved_imask = regs->psw.mask &
223 (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT);
224
225
226 __ctl_load(per_kprobe, 9, 11);
227 regs->psw.mask |= PSW_MASK_PER;
228 regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT);
229 regs->psw.addr = ip | PSW_ADDR_AMODE;
230}
231NOKPROBE_SYMBOL(enable_singlestep);
232
233static void disable_singlestep(struct kprobe_ctlblk *kcb,
234 struct pt_regs *regs,
235 unsigned long ip)
236{
237
238 __ctl_load(kcb->kprobe_saved_ctl, 9, 11);
239 regs->psw.mask &= ~PSW_MASK_PER;
240 regs->psw.mask |= kcb->kprobe_saved_imask;
241 regs->psw.addr = ip | PSW_ADDR_AMODE;
242}
243NOKPROBE_SYMBOL(disable_singlestep);
244
245
246
247
248
249
250static void push_kprobe(struct kprobe_ctlblk *kcb, struct kprobe *p)
251{
252 kcb->prev_kprobe.kp = __this_cpu_read(current_kprobe);
253 kcb->prev_kprobe.status = kcb->kprobe_status;
254 __this_cpu_write(current_kprobe, p);
255}
256NOKPROBE_SYMBOL(push_kprobe);
257
258
259
260
261
262
263static void pop_kprobe(struct kprobe_ctlblk *kcb)
264{
265 __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
266 kcb->kprobe_status = kcb->prev_kprobe.status;
267}
268NOKPROBE_SYMBOL(pop_kprobe);
269
270void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs)
271{
272 ri->ret_addr = (kprobe_opcode_t *) regs->gprs[14];
273
274
275 regs->gprs[14] = (unsigned long) &kretprobe_trampoline;
276}
277NOKPROBE_SYMBOL(arch_prepare_kretprobe);
278
279static void kprobe_reenter_check(struct kprobe_ctlblk *kcb, struct kprobe *p)
280{
281 switch (kcb->kprobe_status) {
282 case KPROBE_HIT_SSDONE:
283 case KPROBE_HIT_ACTIVE:
284 kprobes_inc_nmissed_count(p);
285 break;
286 case KPROBE_HIT_SS:
287 case KPROBE_REENTER:
288 default:
289
290
291
292
293
294 printk(KERN_EMERG "Invalid kprobe detected at %p.\n", p->addr);
295 dump_kprobe(p);
296 BUG();
297 }
298}
299NOKPROBE_SYMBOL(kprobe_reenter_check);
300
301static int kprobe_handler(struct pt_regs *regs)
302{
303 struct kprobe_ctlblk *kcb;
304 struct kprobe *p;
305
306
307
308
309
310
311 preempt_disable();
312 kcb = get_kprobe_ctlblk();
313 p = get_kprobe((void *)((regs->psw.addr & PSW_ADDR_INSN) - 2));
314
315 if (p) {
316 if (kprobe_running()) {
317
318
319
320
321
322
323
324
325
326 kprobe_reenter_check(kcb, p);
327 push_kprobe(kcb, p);
328 kcb->kprobe_status = KPROBE_REENTER;
329 } else {
330
331
332
333
334
335
336
337
338 push_kprobe(kcb, p);
339 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
340 if (p->pre_handler && p->pre_handler(p, regs))
341 return 1;
342 kcb->kprobe_status = KPROBE_HIT_SS;
343 }
344 enable_singlestep(kcb, regs, (unsigned long) p->ainsn.insn);
345 return 1;
346 } else if (kprobe_running()) {
347 p = __this_cpu_read(current_kprobe);
348 if (p->break_handler && p->break_handler(p, regs)) {
349
350
351
352
353
354
355
356 kcb->kprobe_status = KPROBE_HIT_SS;
357 enable_singlestep(kcb, regs,
358 (unsigned long) p->ainsn.insn);
359 return 1;
360 }
361
362
363
364
365
366 }
367
368
369
370
371
372 preempt_enable_no_resched();
373 return 0;
374}
375NOKPROBE_SYMBOL(kprobe_handler);
376
377
378
379
380
381
382
383static void __used kretprobe_trampoline_holder(void)
384{
385 asm volatile(".global kretprobe_trampoline\n"
386 "kretprobe_trampoline: bcr 0,0\n");
387}
388
389
390
391
392static int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
393{
394 struct kretprobe_instance *ri;
395 struct hlist_head *head, empty_rp;
396 struct hlist_node *tmp;
397 unsigned long flags, orig_ret_address;
398 unsigned long trampoline_address;
399 kprobe_opcode_t *correct_ret_addr;
400
401 INIT_HLIST_HEAD(&empty_rp);
402 kretprobe_hash_lock(current, &head, &flags);
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417 ri = NULL;
418 orig_ret_address = 0;
419 correct_ret_addr = NULL;
420 trampoline_address = (unsigned long) &kretprobe_trampoline;
421 hlist_for_each_entry_safe(ri, tmp, head, hlist) {
422 if (ri->task != current)
423
424 continue;
425
426 orig_ret_address = (unsigned long) ri->ret_addr;
427
428 if (orig_ret_address != trampoline_address)
429
430
431
432
433
434 break;
435 }
436
437 kretprobe_assert(ri, orig_ret_address, trampoline_address);
438
439 correct_ret_addr = ri->ret_addr;
440 hlist_for_each_entry_safe(ri, tmp, head, hlist) {
441 if (ri->task != current)
442
443 continue;
444
445 orig_ret_address = (unsigned long) ri->ret_addr;
446
447 if (ri->rp && ri->rp->handler) {
448 ri->ret_addr = correct_ret_addr;
449 ri->rp->handler(ri, regs);
450 }
451
452 recycle_rp_inst(ri, &empty_rp);
453
454 if (orig_ret_address != trampoline_address)
455
456
457
458
459
460 break;
461 }
462
463 regs->psw.addr = orig_ret_address | PSW_ADDR_AMODE;
464
465 pop_kprobe(get_kprobe_ctlblk());
466 kretprobe_hash_unlock(current, &flags);
467 preempt_enable_no_resched();
468
469 hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
470 hlist_del(&ri->hlist);
471 kfree(ri);
472 }
473
474
475
476
477
478 return 1;
479}
480NOKPROBE_SYMBOL(trampoline_probe_handler);
481
482
483
484
485
486
487
488
489
490static void resume_execution(struct kprobe *p, struct pt_regs *regs)
491{
492 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
493 unsigned long ip = regs->psw.addr & PSW_ADDR_INSN;
494 int fixup = probe_get_fixup_type(p->ainsn.insn);
495
496
497 if (p->ainsn.is_ftrace_insn) {
498 struct ftrace_insn *insn = (struct ftrace_insn *) p->addr;
499 struct ftrace_insn call_insn;
500
501 ftrace_generate_call_insn(&call_insn, (unsigned long) p->addr);
502
503
504
505
506
507
508 if (insn->disp == KPROBE_ON_FTRACE_CALL) {
509 ip += call_insn.disp * 2 - MCOUNT_INSN_SIZE;
510 regs->gprs[0] = (unsigned long)p->addr + sizeof(*insn);
511 }
512 }
513
514 if (fixup & FIXUP_PSW_NORMAL)
515 ip += (unsigned long) p->addr - (unsigned long) p->ainsn.insn;
516
517 if (fixup & FIXUP_BRANCH_NOT_TAKEN) {
518 int ilen = insn_length(p->ainsn.insn[0] >> 8);
519 if (ip - (unsigned long) p->ainsn.insn == ilen)
520 ip = (unsigned long) p->addr + ilen;
521 }
522
523 if (fixup & FIXUP_RETURN_REGISTER) {
524 int reg = (p->ainsn.insn[0] & 0xf0) >> 4;
525 regs->gprs[reg] += (unsigned long) p->addr -
526 (unsigned long) p->ainsn.insn;
527 }
528
529 disable_singlestep(kcb, regs, ip);
530}
531NOKPROBE_SYMBOL(resume_execution);
532
533static int post_kprobe_handler(struct pt_regs *regs)
534{
535 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
536 struct kprobe *p = kprobe_running();
537
538 if (!p)
539 return 0;
540
541 if (kcb->kprobe_status != KPROBE_REENTER && p->post_handler) {
542 kcb->kprobe_status = KPROBE_HIT_SSDONE;
543 p->post_handler(p, regs, 0);
544 }
545
546 resume_execution(p, regs);
547 pop_kprobe(kcb);
548 preempt_enable_no_resched();
549
550
551
552
553
554
555 if (regs->psw.mask & PSW_MASK_PER)
556 return 0;
557
558 return 1;
559}
560NOKPROBE_SYMBOL(post_kprobe_handler);
561
562static int kprobe_trap_handler(struct pt_regs *regs, int trapnr)
563{
564 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
565 struct kprobe *p = kprobe_running();
566 const struct exception_table_entry *entry;
567
568 switch(kcb->kprobe_status) {
569 case KPROBE_SWAP_INST:
570
571 return 0;
572 case KPROBE_HIT_SS:
573 case KPROBE_REENTER:
574
575
576
577
578
579
580
581 disable_singlestep(kcb, regs, (unsigned long) p->addr);
582 pop_kprobe(kcb);
583 preempt_enable_no_resched();
584 break;
585 case KPROBE_HIT_ACTIVE:
586 case KPROBE_HIT_SSDONE:
587
588
589
590
591
592 kprobes_inc_nmissed_count(p);
593
594
595
596
597
598
599
600
601 if (p->fault_handler && p->fault_handler(p, regs, trapnr))
602 return 1;
603
604
605
606
607
608 entry = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
609 if (entry) {
610 regs->psw.addr = extable_fixup(entry) | PSW_ADDR_AMODE;
611 return 1;
612 }
613
614
615
616
617
618 break;
619 default:
620 break;
621 }
622 return 0;
623}
624NOKPROBE_SYMBOL(kprobe_trap_handler);
625
626int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
627{
628 int ret;
629
630 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
631 local_irq_disable();
632 ret = kprobe_trap_handler(regs, trapnr);
633 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
634 local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
635 return ret;
636}
637NOKPROBE_SYMBOL(kprobe_fault_handler);
638
639
640
641
642int kprobe_exceptions_notify(struct notifier_block *self,
643 unsigned long val, void *data)
644{
645 struct die_args *args = (struct die_args *) data;
646 struct pt_regs *regs = args->regs;
647 int ret = NOTIFY_DONE;
648
649 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
650 local_irq_disable();
651
652 switch (val) {
653 case DIE_BPT:
654 if (kprobe_handler(regs))
655 ret = NOTIFY_STOP;
656 break;
657 case DIE_SSTEP:
658 if (post_kprobe_handler(regs))
659 ret = NOTIFY_STOP;
660 break;
661 case DIE_TRAP:
662 if (!preemptible() && kprobe_running() &&
663 kprobe_trap_handler(regs, args->trapnr))
664 ret = NOTIFY_STOP;
665 break;
666 default:
667 break;
668 }
669
670 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
671 local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
672
673 return ret;
674}
675NOKPROBE_SYMBOL(kprobe_exceptions_notify);
676
677int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
678{
679 struct jprobe *jp = container_of(p, struct jprobe, kp);
680 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
681 unsigned long stack;
682
683 memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs));
684
685
686 regs->psw.addr = (unsigned long) jp->entry | PSW_ADDR_AMODE;
687 regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT);
688
689
690 stack = (unsigned long) regs->gprs[15];
691
692 memcpy(kcb->jprobes_stack, (void *) stack, MIN_STACK_SIZE(stack));
693 return 1;
694}
695NOKPROBE_SYMBOL(setjmp_pre_handler);
696
697void jprobe_return(void)
698{
699 asm volatile(".word 0x0002");
700}
701NOKPROBE_SYMBOL(jprobe_return);
702
703int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
704{
705 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
706 unsigned long stack;
707
708 stack = (unsigned long) kcb->jprobe_saved_regs.gprs[15];
709
710
711 memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));
712
713 memcpy((void *) stack, kcb->jprobes_stack, MIN_STACK_SIZE(stack));
714 preempt_enable_no_resched();
715 return 1;
716}
717NOKPROBE_SYMBOL(longjmp_break_handler);
718
719static struct kprobe trampoline = {
720 .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
721 .pre_handler = trampoline_probe_handler
722};
723
724int __init arch_init_kprobes(void)
725{
726 return register_kprobe(&trampoline);
727}
728
729int arch_trampoline_kprobe(struct kprobe *p)
730{
731 return p->addr == (kprobe_opcode_t *) &kretprobe_trampoline;
732}
733NOKPROBE_SYMBOL(arch_trampoline_kprobe);
734