1
2
3
4
5
6
7
8
9
10#include <linux/kprobes.h>
11#include <linux/ptrace.h>
12#include <linux/preempt.h>
13#include <linux/stop_machine.h>
14#include <linux/kdebug.h>
15#include <linux/uaccess.h>
16#include <linux/extable.h>
17#include <linux/module.h>
18#include <linux/slab.h>
19#include <linux/hardirq.h>
20#include <linux/ftrace.h>
21#include <asm/set_memory.h>
22#include <asm/sections.h>
23#include <asm/dis.h>
24
25DEFINE_PER_CPU(struct kprobe *, current_kprobe);
26DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
27
28struct kretprobe_blackpoint kretprobe_blacklist[] = { };
29
30DEFINE_INSN_CACHE_OPS(dmainsn);
31
32static void *alloc_dmainsn_page(void)
33{
34 void *page;
35
36 page = (void *) __get_free_page(GFP_KERNEL | GFP_DMA);
37 if (page)
38 set_memory_x((unsigned long) page, 1);
39 return page;
40}
41
42static void free_dmainsn_page(void *page)
43{
44 set_memory_nx((unsigned long) page, 1);
45 free_page((unsigned long)page);
46}
47
48struct kprobe_insn_cache kprobe_dmainsn_slots = {
49 .mutex = __MUTEX_INITIALIZER(kprobe_dmainsn_slots.mutex),
50 .alloc = alloc_dmainsn_page,
51 .free = free_dmainsn_page,
52 .pages = LIST_HEAD_INIT(kprobe_dmainsn_slots.pages),
53 .insn_size = MAX_INSN_SIZE,
54};
55
56static void copy_instruction(struct kprobe *p)
57{
58 unsigned long ip = (unsigned long) p->addr;
59 s64 disp, new_disp;
60 u64 addr, new_addr;
61
62 if (ftrace_location(ip) == ip) {
63
64
65
66
67
68
69 ftrace_generate_nop_insn((struct ftrace_insn *)p->ainsn.insn);
70 p->ainsn.is_ftrace_insn = 1;
71 } else
72 memcpy(p->ainsn.insn, p->addr, insn_length(*p->addr >> 8));
73 p->opcode = p->ainsn.insn[0];
74 if (!probe_is_insn_relative_long(p->ainsn.insn))
75 return;
76
77
78
79
80
81
82
83 disp = *(s32 *)&p->ainsn.insn[1];
84 addr = (u64)(unsigned long)p->addr;
85 new_addr = (u64)(unsigned long)p->ainsn.insn;
86 new_disp = ((addr + (disp * 2)) - new_addr) / 2;
87 *(s32 *)&p->ainsn.insn[1] = new_disp;
88}
89NOKPROBE_SYMBOL(copy_instruction);
90
91static inline int is_kernel_addr(void *addr)
92{
93 return addr < (void *)_end;
94}
95
96static int s390_get_insn_slot(struct kprobe *p)
97{
98
99
100
101
102
103 p->ainsn.insn = NULL;
104 if (is_kernel_addr(p->addr))
105 p->ainsn.insn = get_dmainsn_slot();
106 else if (is_module_addr(p->addr))
107 p->ainsn.insn = get_insn_slot();
108 return p->ainsn.insn ? 0 : -ENOMEM;
109}
110NOKPROBE_SYMBOL(s390_get_insn_slot);
111
112static void s390_free_insn_slot(struct kprobe *p)
113{
114 if (!p->ainsn.insn)
115 return;
116 if (is_kernel_addr(p->addr))
117 free_dmainsn_slot(p->ainsn.insn, 0);
118 else
119 free_insn_slot(p->ainsn.insn, 0);
120 p->ainsn.insn = NULL;
121}
122NOKPROBE_SYMBOL(s390_free_insn_slot);
123
124int arch_prepare_kprobe(struct kprobe *p)
125{
126 if ((unsigned long) p->addr & 0x01)
127 return -EINVAL;
128
129 if (probe_is_prohibited_opcode(p->addr))
130 return -EINVAL;
131 if (s390_get_insn_slot(p))
132 return -ENOMEM;
133 copy_instruction(p);
134 return 0;
135}
136NOKPROBE_SYMBOL(arch_prepare_kprobe);
137
138int arch_check_ftrace_location(struct kprobe *p)
139{
140 return 0;
141}
142
143struct swap_insn_args {
144 struct kprobe *p;
145 unsigned int arm_kprobe : 1;
146};
147
148static int swap_instruction(void *data)
149{
150 struct swap_insn_args *args = data;
151 struct ftrace_insn new_insn, *insn;
152 struct kprobe *p = args->p;
153 size_t len;
154
155 new_insn.opc = args->arm_kprobe ? BREAKPOINT_INSTRUCTION : p->opcode;
156 len = sizeof(new_insn.opc);
157 if (!p->ainsn.is_ftrace_insn)
158 goto skip_ftrace;
159 len = sizeof(new_insn);
160 insn = (struct ftrace_insn *) p->addr;
161 if (args->arm_kprobe) {
162 if (is_ftrace_nop(insn))
163 new_insn.disp = KPROBE_ON_FTRACE_NOP;
164 else
165 new_insn.disp = KPROBE_ON_FTRACE_CALL;
166 } else {
167 ftrace_generate_call_insn(&new_insn, (unsigned long)p->addr);
168 if (insn->disp == KPROBE_ON_FTRACE_NOP)
169 ftrace_generate_nop_insn(&new_insn);
170 }
171skip_ftrace:
172 s390_kernel_write(p->addr, &new_insn, len);
173 return 0;
174}
175NOKPROBE_SYMBOL(swap_instruction);
176
177void arch_arm_kprobe(struct kprobe *p)
178{
179 struct swap_insn_args args = {.p = p, .arm_kprobe = 1};
180
181 stop_machine_cpuslocked(swap_instruction, &args, NULL);
182}
183NOKPROBE_SYMBOL(arch_arm_kprobe);
184
185void arch_disarm_kprobe(struct kprobe *p)
186{
187 struct swap_insn_args args = {.p = p, .arm_kprobe = 0};
188
189 stop_machine_cpuslocked(swap_instruction, &args, NULL);
190}
191NOKPROBE_SYMBOL(arch_disarm_kprobe);
192
193void arch_remove_kprobe(struct kprobe *p)
194{
195 s390_free_insn_slot(p);
196}
197NOKPROBE_SYMBOL(arch_remove_kprobe);
198
199static void enable_singlestep(struct kprobe_ctlblk *kcb,
200 struct pt_regs *regs,
201 unsigned long ip)
202{
203 struct per_regs per_kprobe;
204
205
206 per_kprobe.control = PER_EVENT_IFETCH;
207 per_kprobe.start = ip;
208 per_kprobe.end = ip;
209
210
211 __ctl_store(kcb->kprobe_saved_ctl, 9, 11);
212 kcb->kprobe_saved_imask = regs->psw.mask &
213 (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT);
214
215
216 __ctl_load(per_kprobe, 9, 11);
217 regs->psw.mask |= PSW_MASK_PER;
218 regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT);
219 regs->psw.addr = ip;
220}
221NOKPROBE_SYMBOL(enable_singlestep);
222
223static void disable_singlestep(struct kprobe_ctlblk *kcb,
224 struct pt_regs *regs,
225 unsigned long ip)
226{
227
228 __ctl_load(kcb->kprobe_saved_ctl, 9, 11);
229 regs->psw.mask &= ~PSW_MASK_PER;
230 regs->psw.mask |= kcb->kprobe_saved_imask;
231 regs->psw.addr = ip;
232}
233NOKPROBE_SYMBOL(disable_singlestep);
234
235
236
237
238
239
240static void push_kprobe(struct kprobe_ctlblk *kcb, struct kprobe *p)
241{
242 kcb->prev_kprobe.kp = __this_cpu_read(current_kprobe);
243 kcb->prev_kprobe.status = kcb->kprobe_status;
244 __this_cpu_write(current_kprobe, p);
245}
246NOKPROBE_SYMBOL(push_kprobe);
247
248
249
250
251
252
253static void pop_kprobe(struct kprobe_ctlblk *kcb)
254{
255 __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
256 kcb->kprobe_status = kcb->prev_kprobe.status;
257}
258NOKPROBE_SYMBOL(pop_kprobe);
259
260void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs)
261{
262 ri->ret_addr = (kprobe_opcode_t *) regs->gprs[14];
263
264
265 regs->gprs[14] = (unsigned long) &kretprobe_trampoline;
266}
267NOKPROBE_SYMBOL(arch_prepare_kretprobe);
268
269static void kprobe_reenter_check(struct kprobe_ctlblk *kcb, struct kprobe *p)
270{
271 switch (kcb->kprobe_status) {
272 case KPROBE_HIT_SSDONE:
273 case KPROBE_HIT_ACTIVE:
274 kprobes_inc_nmissed_count(p);
275 break;
276 case KPROBE_HIT_SS:
277 case KPROBE_REENTER:
278 default:
279
280
281
282
283
284 pr_err("Invalid kprobe detected.\n");
285 dump_kprobe(p);
286 BUG();
287 }
288}
289NOKPROBE_SYMBOL(kprobe_reenter_check);
290
291static int kprobe_handler(struct pt_regs *regs)
292{
293 struct kprobe_ctlblk *kcb;
294 struct kprobe *p;
295
296
297
298
299
300
301 preempt_disable();
302 kcb = get_kprobe_ctlblk();
303 p = get_kprobe((void *)(regs->psw.addr - 2));
304
305 if (p) {
306 if (kprobe_running()) {
307
308
309
310
311
312
313
314
315
316 kprobe_reenter_check(kcb, p);
317 push_kprobe(kcb, p);
318 kcb->kprobe_status = KPROBE_REENTER;
319 } else {
320
321
322
323
324
325
326
327 push_kprobe(kcb, p);
328 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
329 if (p->pre_handler && p->pre_handler(p, regs)) {
330 pop_kprobe(kcb);
331 preempt_enable_no_resched();
332 return 1;
333 }
334 kcb->kprobe_status = KPROBE_HIT_SS;
335 }
336 enable_singlestep(kcb, regs, (unsigned long) p->ainsn.insn);
337 return 1;
338 }
339
340
341
342
343
344 preempt_enable_no_resched();
345 return 0;
346}
347NOKPROBE_SYMBOL(kprobe_handler);
348
349
350
351
352
353
354
355static void __used kretprobe_trampoline_holder(void)
356{
357 asm volatile(".global kretprobe_trampoline\n"
358 "kretprobe_trampoline: bcr 0,0\n");
359}
360
361
362
363
364static int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
365{
366 struct kretprobe_instance *ri;
367 struct hlist_head *head, empty_rp;
368 struct hlist_node *tmp;
369 unsigned long flags, orig_ret_address;
370 unsigned long trampoline_address;
371 kprobe_opcode_t *correct_ret_addr;
372
373 INIT_HLIST_HEAD(&empty_rp);
374 kretprobe_hash_lock(current, &head, &flags);
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389 ri = NULL;
390 orig_ret_address = 0;
391 correct_ret_addr = NULL;
392 trampoline_address = (unsigned long) &kretprobe_trampoline;
393 hlist_for_each_entry_safe(ri, tmp, head, hlist) {
394 if (ri->task != current)
395
396 continue;
397
398 orig_ret_address = (unsigned long) ri->ret_addr;
399
400 if (orig_ret_address != trampoline_address)
401
402
403
404
405
406 break;
407 }
408
409 kretprobe_assert(ri, orig_ret_address, trampoline_address);
410
411 correct_ret_addr = ri->ret_addr;
412 hlist_for_each_entry_safe(ri, tmp, head, hlist) {
413 if (ri->task != current)
414
415 continue;
416
417 orig_ret_address = (unsigned long) ri->ret_addr;
418
419 if (ri->rp && ri->rp->handler) {
420 ri->ret_addr = correct_ret_addr;
421 ri->rp->handler(ri, regs);
422 }
423
424 recycle_rp_inst(ri, &empty_rp);
425
426 if (orig_ret_address != trampoline_address)
427
428
429
430
431
432 break;
433 }
434
435 regs->psw.addr = orig_ret_address;
436
437 kretprobe_hash_unlock(current, &flags);
438
439 hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
440 hlist_del(&ri->hlist);
441 kfree(ri);
442 }
443
444
445
446
447
448 return 1;
449}
450NOKPROBE_SYMBOL(trampoline_probe_handler);
451
452
453
454
455
456
457
458
459
460static void resume_execution(struct kprobe *p, struct pt_regs *regs)
461{
462 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
463 unsigned long ip = regs->psw.addr;
464 int fixup = probe_get_fixup_type(p->ainsn.insn);
465
466
467 if (p->ainsn.is_ftrace_insn) {
468 struct ftrace_insn *insn = (struct ftrace_insn *) p->addr;
469 struct ftrace_insn call_insn;
470
471 ftrace_generate_call_insn(&call_insn, (unsigned long) p->addr);
472
473
474
475
476
477
478 if (insn->disp == KPROBE_ON_FTRACE_CALL) {
479 ip += call_insn.disp * 2 - MCOUNT_INSN_SIZE;
480 regs->gprs[0] = (unsigned long)p->addr + sizeof(*insn);
481 }
482 }
483
484 if (fixup & FIXUP_PSW_NORMAL)
485 ip += (unsigned long) p->addr - (unsigned long) p->ainsn.insn;
486
487 if (fixup & FIXUP_BRANCH_NOT_TAKEN) {
488 int ilen = insn_length(p->ainsn.insn[0] >> 8);
489 if (ip - (unsigned long) p->ainsn.insn == ilen)
490 ip = (unsigned long) p->addr + ilen;
491 }
492
493 if (fixup & FIXUP_RETURN_REGISTER) {
494 int reg = (p->ainsn.insn[0] & 0xf0) >> 4;
495 regs->gprs[reg] += (unsigned long) p->addr -
496 (unsigned long) p->ainsn.insn;
497 }
498
499 disable_singlestep(kcb, regs, ip);
500}
501NOKPROBE_SYMBOL(resume_execution);
502
503static int post_kprobe_handler(struct pt_regs *regs)
504{
505 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
506 struct kprobe *p = kprobe_running();
507
508 if (!p)
509 return 0;
510
511 if (kcb->kprobe_status != KPROBE_REENTER && p->post_handler) {
512 kcb->kprobe_status = KPROBE_HIT_SSDONE;
513 p->post_handler(p, regs, 0);
514 }
515
516 resume_execution(p, regs);
517 pop_kprobe(kcb);
518 preempt_enable_no_resched();
519
520
521
522
523
524
525 if (regs->psw.mask & PSW_MASK_PER)
526 return 0;
527
528 return 1;
529}
530NOKPROBE_SYMBOL(post_kprobe_handler);
531
532static int kprobe_trap_handler(struct pt_regs *regs, int trapnr)
533{
534 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
535 struct kprobe *p = kprobe_running();
536 const struct exception_table_entry *entry;
537
538 switch(kcb->kprobe_status) {
539 case KPROBE_HIT_SS:
540 case KPROBE_REENTER:
541
542
543
544
545
546
547
548 disable_singlestep(kcb, regs, (unsigned long) p->addr);
549 pop_kprobe(kcb);
550 preempt_enable_no_resched();
551 break;
552 case KPROBE_HIT_ACTIVE:
553 case KPROBE_HIT_SSDONE:
554
555
556
557
558
559 kprobes_inc_nmissed_count(p);
560
561
562
563
564
565
566
567
568 if (p->fault_handler && p->fault_handler(p, regs, trapnr))
569 return 1;
570
571
572
573
574
575 entry = search_exception_tables(regs->psw.addr);
576 if (entry) {
577 regs->psw.addr = extable_fixup(entry);
578 return 1;
579 }
580
581
582
583
584
585 break;
586 default:
587 break;
588 }
589 return 0;
590}
591NOKPROBE_SYMBOL(kprobe_trap_handler);
592
593int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
594{
595 int ret;
596
597 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
598 local_irq_disable();
599 ret = kprobe_trap_handler(regs, trapnr);
600 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
601 local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
602 return ret;
603}
604NOKPROBE_SYMBOL(kprobe_fault_handler);
605
606
607
608
609int kprobe_exceptions_notify(struct notifier_block *self,
610 unsigned long val, void *data)
611{
612 struct die_args *args = (struct die_args *) data;
613 struct pt_regs *regs = args->regs;
614 int ret = NOTIFY_DONE;
615
616 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
617 local_irq_disable();
618
619 switch (val) {
620 case DIE_BPT:
621 if (kprobe_handler(regs))
622 ret = NOTIFY_STOP;
623 break;
624 case DIE_SSTEP:
625 if (post_kprobe_handler(regs))
626 ret = NOTIFY_STOP;
627 break;
628 case DIE_TRAP:
629 if (!preemptible() && kprobe_running() &&
630 kprobe_trap_handler(regs, args->trapnr))
631 ret = NOTIFY_STOP;
632 break;
633 default:
634 break;
635 }
636
637 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
638 local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
639
640 return ret;
641}
642NOKPROBE_SYMBOL(kprobe_exceptions_notify);
643
644static struct kprobe trampoline = {
645 .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
646 .pre_handler = trampoline_probe_handler
647};
648
649int __init arch_init_kprobes(void)
650{
651 return register_kprobe(&trampoline);
652}
653
654int arch_trampoline_kprobe(struct kprobe *p)
655{
656 return p->addr == (kprobe_opcode_t *) &kretprobe_trampoline;
657}
658NOKPROBE_SYMBOL(arch_trampoline_kprobe);
659