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26#include <linux/kprobes.h>
27#include <linux/preempt.h>
28#include <linux/uaccess.h>
29#include <linux/kdebug.h>
30#include <linux/slab.h>
31
32#include <asm/ptrace.h>
33#include <asm/branch.h>
34#include <asm/break.h>
35#include <asm/inst.h>
36
37static const union mips_instruction breakpoint_insn = {
38 .b_format = {
39 .opcode = spec_op,
40 .code = BRK_KPROBE_BP,
41 .func = break_op
42 }
43};
44
45static const union mips_instruction breakpoint2_insn = {
46 .b_format = {
47 .opcode = spec_op,
48 .code = BRK_KPROBE_SSTEPBP,
49 .func = break_op
50 }
51};
52
53DEFINE_PER_CPU(struct kprobe *, current_kprobe);
54DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
55
56static int __kprobes insn_has_delayslot(union mips_instruction insn)
57{
58 switch (insn.i_format.opcode) {
59
60
61
62
63
64 case spec_op:
65 switch (insn.r_format.func) {
66 case jr_op:
67 case jalr_op:
68 break;
69 default:
70 goto insn_ok;
71 }
72
73
74
75
76
77
78 case bcond_op:
79
80
81
82
83 case jal_op:
84 case j_op:
85
86
87
88
89 case beq_op:
90 case beql_op:
91 case bne_op:
92 case bnel_op:
93 case blez_op:
94 case blezl_op:
95 case bgtz_op:
96 case bgtzl_op:
97
98
99
100
101 case cop1_op:
102
103#ifdef CONFIG_CPU_CAVIUM_OCTEON
104 case lwc2_op:
105 case ldc2_op:
106 case swc2_op:
107 case sdc2_op:
108#endif
109 return 1;
110 default:
111 break;
112 }
113insn_ok:
114 return 0;
115}
116
117
118
119
120
121
122
123
124static int __kprobes insn_has_ll_or_sc(union mips_instruction insn)
125{
126 int ret = 0;
127
128 switch (insn.i_format.opcode) {
129 case ll_op:
130 case lld_op:
131 case sc_op:
132 case scd_op:
133 ret = 1;
134 break;
135 default:
136 break;
137 }
138 return ret;
139}
140
141int __kprobes arch_prepare_kprobe(struct kprobe *p)
142{
143 union mips_instruction insn;
144 union mips_instruction prev_insn;
145 int ret = 0;
146
147 insn = p->addr[0];
148
149 if (insn_has_ll_or_sc(insn)) {
150 pr_notice("Kprobes for ll and sc instructions are not"
151 "supported\n");
152 ret = -EINVAL;
153 goto out;
154 }
155
156 if ((probe_kernel_read(&prev_insn, p->addr - 1,
157 sizeof(mips_instruction)) == 0) &&
158 insn_has_delayslot(prev_insn)) {
159 pr_notice("Kprobes for branch delayslot are not supported\n");
160 ret = -EINVAL;
161 goto out;
162 }
163
164
165 p->ainsn.insn = get_insn_slot();
166 if (!p->ainsn.insn) {
167 ret = -ENOMEM;
168 goto out;
169 }
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184 if (insn_has_delayslot(insn))
185 memcpy(&p->ainsn.insn[0], p->addr + 1, sizeof(kprobe_opcode_t));
186 else
187 memcpy(&p->ainsn.insn[0], p->addr, sizeof(kprobe_opcode_t));
188
189 p->ainsn.insn[1] = breakpoint2_insn;
190 p->opcode = *p->addr;
191
192out:
193 return ret;
194}
195
196void __kprobes arch_arm_kprobe(struct kprobe *p)
197{
198 *p->addr = breakpoint_insn;
199 flush_insn_slot(p);
200}
201
202void __kprobes arch_disarm_kprobe(struct kprobe *p)
203{
204 *p->addr = p->opcode;
205 flush_insn_slot(p);
206}
207
208void __kprobes arch_remove_kprobe(struct kprobe *p)
209{
210 if (p->ainsn.insn) {
211 free_insn_slot(p->ainsn.insn, 0);
212 p->ainsn.insn = NULL;
213 }
214}
215
216static void save_previous_kprobe(struct kprobe_ctlblk *kcb)
217{
218 kcb->prev_kprobe.kp = kprobe_running();
219 kcb->prev_kprobe.status = kcb->kprobe_status;
220 kcb->prev_kprobe.old_SR = kcb->kprobe_old_SR;
221 kcb->prev_kprobe.saved_SR = kcb->kprobe_saved_SR;
222 kcb->prev_kprobe.saved_epc = kcb->kprobe_saved_epc;
223}
224
225static void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
226{
227 __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
228 kcb->kprobe_status = kcb->prev_kprobe.status;
229 kcb->kprobe_old_SR = kcb->prev_kprobe.old_SR;
230 kcb->kprobe_saved_SR = kcb->prev_kprobe.saved_SR;
231 kcb->kprobe_saved_epc = kcb->prev_kprobe.saved_epc;
232}
233
234static void set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
235 struct kprobe_ctlblk *kcb)
236{
237 __get_cpu_var(current_kprobe) = p;
238 kcb->kprobe_saved_SR = kcb->kprobe_old_SR = (regs->cp0_status & ST0_IE);
239 kcb->kprobe_saved_epc = regs->cp0_epc;
240}
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255static int evaluate_branch_instruction(struct kprobe *p, struct pt_regs *regs,
256 struct kprobe_ctlblk *kcb)
257{
258 union mips_instruction insn = p->opcode;
259 long epc;
260 int ret = 0;
261
262 epc = regs->cp0_epc;
263 if (epc & 3)
264 goto unaligned;
265
266 if (p->ainsn.insn->word == 0)
267 kcb->flags |= SKIP_DELAYSLOT;
268 else
269 kcb->flags &= ~SKIP_DELAYSLOT;
270
271 ret = __compute_return_epc_for_insn(regs, insn);
272 if (ret < 0)
273 return ret;
274
275 if (ret == BRANCH_LIKELY_TAKEN)
276 kcb->flags |= SKIP_DELAYSLOT;
277
278 kcb->target_epc = regs->cp0_epc;
279
280 return 0;
281
282unaligned:
283 pr_notice("%s: unaligned epc - sending SIGBUS.\n", current->comm);
284 force_sig(SIGBUS, current);
285 return -EFAULT;
286
287}
288
289static void prepare_singlestep(struct kprobe *p, struct pt_regs *regs,
290 struct kprobe_ctlblk *kcb)
291{
292 int ret = 0;
293
294 regs->cp0_status &= ~ST0_IE;
295
296
297 if (p->opcode.word == breakpoint_insn.word ||
298 p->opcode.word == breakpoint2_insn.word)
299 regs->cp0_epc = (unsigned long)p->addr;
300 else if (insn_has_delayslot(p->opcode)) {
301 ret = evaluate_branch_instruction(p, regs, kcb);
302 if (ret < 0) {
303 pr_notice("Kprobes: Error in evaluating branch\n");
304 return;
305 }
306 }
307 regs->cp0_epc = (unsigned long)&p->ainsn.insn[0];
308}
309
310
311
312
313
314
315
316
317
318
319
320
321
322static void __kprobes resume_execution(struct kprobe *p,
323 struct pt_regs *regs,
324 struct kprobe_ctlblk *kcb)
325{
326 if (insn_has_delayslot(p->opcode))
327 regs->cp0_epc = kcb->target_epc;
328 else {
329 unsigned long orig_epc = kcb->kprobe_saved_epc;
330 regs->cp0_epc = orig_epc + 4;
331 }
332}
333
334static int __kprobes kprobe_handler(struct pt_regs *regs)
335{
336 struct kprobe *p;
337 int ret = 0;
338 kprobe_opcode_t *addr;
339 struct kprobe_ctlblk *kcb;
340
341 addr = (kprobe_opcode_t *) regs->cp0_epc;
342
343
344
345
346
347 preempt_disable();
348 kcb = get_kprobe_ctlblk();
349
350
351 if (kprobe_running()) {
352 p = get_kprobe(addr);
353 if (p) {
354 if (kcb->kprobe_status == KPROBE_HIT_SS &&
355 p->ainsn.insn->word == breakpoint_insn.word) {
356 regs->cp0_status &= ~ST0_IE;
357 regs->cp0_status |= kcb->kprobe_saved_SR;
358 goto no_kprobe;
359 }
360
361
362
363
364
365
366
367 save_previous_kprobe(kcb);
368 set_current_kprobe(p, regs, kcb);
369 kprobes_inc_nmissed_count(p);
370 prepare_singlestep(p, regs, kcb);
371 kcb->kprobe_status = KPROBE_REENTER;
372 if (kcb->flags & SKIP_DELAYSLOT) {
373 resume_execution(p, regs, kcb);
374 restore_previous_kprobe(kcb);
375 preempt_enable_no_resched();
376 }
377 return 1;
378 } else {
379 if (addr->word != breakpoint_insn.word) {
380
381
382
383
384
385 ret = 1;
386 goto no_kprobe;
387 }
388 p = __get_cpu_var(current_kprobe);
389 if (p->break_handler && p->break_handler(p, regs))
390 goto ss_probe;
391 }
392 goto no_kprobe;
393 }
394
395 p = get_kprobe(addr);
396 if (!p) {
397 if (addr->word != breakpoint_insn.word) {
398
399
400
401
402
403
404
405 ret = 1;
406 }
407
408 goto no_kprobe;
409 }
410
411 set_current_kprobe(p, regs, kcb);
412 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
413
414 if (p->pre_handler && p->pre_handler(p, regs)) {
415
416 return 1;
417 }
418
419ss_probe:
420 prepare_singlestep(p, regs, kcb);
421 if (kcb->flags & SKIP_DELAYSLOT) {
422 kcb->kprobe_status = KPROBE_HIT_SSDONE;
423 if (p->post_handler)
424 p->post_handler(p, regs, 0);
425 resume_execution(p, regs, kcb);
426 preempt_enable_no_resched();
427 } else
428 kcb->kprobe_status = KPROBE_HIT_SS;
429
430 return 1;
431
432no_kprobe:
433 preempt_enable_no_resched();
434 return ret;
435
436}
437
438static inline int post_kprobe_handler(struct pt_regs *regs)
439{
440 struct kprobe *cur = kprobe_running();
441 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
442
443 if (!cur)
444 return 0;
445
446 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
447 kcb->kprobe_status = KPROBE_HIT_SSDONE;
448 cur->post_handler(cur, regs, 0);
449 }
450
451 resume_execution(cur, regs, kcb);
452
453 regs->cp0_status |= kcb->kprobe_saved_SR;
454
455
456 if (kcb->kprobe_status == KPROBE_REENTER) {
457 restore_previous_kprobe(kcb);
458 goto out;
459 }
460 reset_current_kprobe();
461out:
462 preempt_enable_no_resched();
463
464 return 1;
465}
466
467static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
468{
469 struct kprobe *cur = kprobe_running();
470 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
471
472 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
473 return 1;
474
475 if (kcb->kprobe_status & KPROBE_HIT_SS) {
476 resume_execution(cur, regs, kcb);
477 regs->cp0_status |= kcb->kprobe_old_SR;
478
479 reset_current_kprobe();
480 preempt_enable_no_resched();
481 }
482 return 0;
483}
484
485
486
487
488int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
489 unsigned long val, void *data)
490{
491
492 struct die_args *args = (struct die_args *)data;
493 int ret = NOTIFY_DONE;
494
495 switch (val) {
496 case DIE_BREAK:
497 if (kprobe_handler(args->regs))
498 ret = NOTIFY_STOP;
499 break;
500 case DIE_SSTEPBP:
501 if (post_kprobe_handler(args->regs))
502 ret = NOTIFY_STOP;
503 break;
504
505 case DIE_PAGE_FAULT:
506
507 preempt_disable();
508
509 if (kprobe_running()
510 && kprobe_fault_handler(args->regs, args->trapnr))
511 ret = NOTIFY_STOP;
512 preempt_enable();
513 break;
514 default:
515 break;
516 }
517 return ret;
518}
519
520int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
521{
522 struct jprobe *jp = container_of(p, struct jprobe, kp);
523 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
524
525 kcb->jprobe_saved_regs = *regs;
526 kcb->jprobe_saved_sp = regs->regs[29];
527
528 memcpy(kcb->jprobes_stack, (void *)kcb->jprobe_saved_sp,
529 MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
530
531 regs->cp0_epc = (unsigned long)(jp->entry);
532
533 return 1;
534}
535
536
537void jprobe_return_end(void);
538
539void __kprobes jprobe_return(void)
540{
541
542 asm volatile(
543 "break 0,%0\n\t"
544 ".globl jprobe_return_end\n"
545 "jprobe_return_end:\n"
546 : : "n" (BRK_KPROBE_BP) : "memory");
547}
548
549int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
550{
551 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
552
553 if (regs->cp0_epc >= (unsigned long)jprobe_return &&
554 regs->cp0_epc <= (unsigned long)jprobe_return_end) {
555 *regs = kcb->jprobe_saved_regs;
556 memcpy((void *)kcb->jprobe_saved_sp, kcb->jprobes_stack,
557 MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
558 preempt_enable_no_resched();
559
560 return 1;
561 }
562 return 0;
563}
564
565
566
567
568
569
570
571static void __used kretprobe_trampoline_holder(void)
572{
573 asm volatile(
574 ".set push\n\t"
575
576 ".set noreorder\n\t"
577 "nop\n\t"
578 ".global kretprobe_trampoline\n"
579 "kretprobe_trampoline:\n\t"
580 "nop\n\t"
581 ".set pop"
582 : : : "memory");
583}
584
585void kretprobe_trampoline(void);
586
587void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
588 struct pt_regs *regs)
589{
590 ri->ret_addr = (kprobe_opcode_t *) regs->regs[31];
591
592
593 regs->regs[31] = (unsigned long)kretprobe_trampoline;
594}
595
596
597
598
599static int __kprobes trampoline_probe_handler(struct kprobe *p,
600 struct pt_regs *regs)
601{
602 struct kretprobe_instance *ri = NULL;
603 struct hlist_head *head, empty_rp;
604 struct hlist_node *tmp;
605 unsigned long flags, orig_ret_address = 0;
606 unsigned long trampoline_address = (unsigned long)kretprobe_trampoline;
607
608 INIT_HLIST_HEAD(&empty_rp);
609 kretprobe_hash_lock(current, &head, &flags);
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624 hlist_for_each_entry_safe(ri, tmp, head, hlist) {
625 if (ri->task != current)
626
627 continue;
628
629 if (ri->rp && ri->rp->handler)
630 ri->rp->handler(ri, regs);
631
632 orig_ret_address = (unsigned long)ri->ret_addr;
633 recycle_rp_inst(ri, &empty_rp);
634
635 if (orig_ret_address != trampoline_address)
636
637
638
639
640
641 break;
642 }
643
644 kretprobe_assert(ri, orig_ret_address, trampoline_address);
645 instruction_pointer(regs) = orig_ret_address;
646
647 reset_current_kprobe();
648 kretprobe_hash_unlock(current, &flags);
649 preempt_enable_no_resched();
650
651 hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
652 hlist_del(&ri->hlist);
653 kfree(ri);
654 }
655
656
657
658
659
660 return 1;
661}
662
663int __kprobes arch_trampoline_kprobe(struct kprobe *p)
664{
665 if (p->addr == (kprobe_opcode_t *)kretprobe_trampoline)
666 return 1;
667
668 return 0;
669}
670
671static struct kprobe trampoline_p = {
672 .addr = (kprobe_opcode_t *)kretprobe_trampoline,
673 .pre_handler = trampoline_probe_handler
674};
675
676int __init arch_init_kprobes(void)
677{
678 return register_kprobe(&trampoline_p);
679}
680