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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(s390_insn);
31
32static int insn_page_in_use;
33static char insn_page[PAGE_SIZE] __aligned(PAGE_SIZE);
34
35static void *alloc_s390_insn_page(void)
36{
37 if (xchg(&insn_page_in_use, 1) == 1)
38 return NULL;
39 set_memory_x((unsigned long) &insn_page, 1);
40 return &insn_page;
41}
42
43static void free_s390_insn_page(void *page)
44{
45 set_memory_nx((unsigned long) page, 1);
46 xchg(&insn_page_in_use, 0);
47}
48
49struct kprobe_insn_cache kprobe_s390_insn_slots = {
50 .mutex = __MUTEX_INITIALIZER(kprobe_s390_insn_slots.mutex),
51 .alloc = alloc_s390_insn_page,
52 .free = free_s390_insn_page,
53 .pages = LIST_HEAD_INIT(kprobe_s390_insn_slots.pages),
54 .insn_size = MAX_INSN_SIZE,
55};
56
57static void copy_instruction(struct kprobe *p)
58{
59 s64 disp, new_disp;
60 u64 addr, new_addr;
61
62 memcpy(p->ainsn.insn, p->addr, insn_length(*p->addr >> 8));
63 p->opcode = p->ainsn.insn[0];
64 if (!probe_is_insn_relative_long(p->ainsn.insn))
65 return;
66
67
68
69
70
71
72
73 disp = *(s32 *)&p->ainsn.insn[1];
74 addr = (u64)(unsigned long)p->addr;
75 new_addr = (u64)(unsigned long)p->ainsn.insn;
76 new_disp = ((addr + (disp * 2)) - new_addr) / 2;
77 *(s32 *)&p->ainsn.insn[1] = new_disp;
78}
79NOKPROBE_SYMBOL(copy_instruction);
80
81static inline int is_kernel_addr(void *addr)
82{
83 return addr < (void *)_end;
84}
85
86static int s390_get_insn_slot(struct kprobe *p)
87{
88
89
90
91
92
93 p->ainsn.insn = NULL;
94 if (is_kernel_addr(p->addr))
95 p->ainsn.insn = get_s390_insn_slot();
96 else if (is_module_addr(p->addr))
97 p->ainsn.insn = get_insn_slot();
98 return p->ainsn.insn ? 0 : -ENOMEM;
99}
100NOKPROBE_SYMBOL(s390_get_insn_slot);
101
102static void s390_free_insn_slot(struct kprobe *p)
103{
104 if (!p->ainsn.insn)
105 return;
106 if (is_kernel_addr(p->addr))
107 free_s390_insn_slot(p->ainsn.insn, 0);
108 else
109 free_insn_slot(p->ainsn.insn, 0);
110 p->ainsn.insn = NULL;
111}
112NOKPROBE_SYMBOL(s390_free_insn_slot);
113
114int arch_prepare_kprobe(struct kprobe *p)
115{
116 if ((unsigned long) p->addr & 0x01)
117 return -EINVAL;
118
119 if (probe_is_prohibited_opcode(p->addr))
120 return -EINVAL;
121 if (s390_get_insn_slot(p))
122 return -ENOMEM;
123 copy_instruction(p);
124 return 0;
125}
126NOKPROBE_SYMBOL(arch_prepare_kprobe);
127
128struct swap_insn_args {
129 struct kprobe *p;
130 unsigned int arm_kprobe : 1;
131};
132
133static int swap_instruction(void *data)
134{
135 struct swap_insn_args *args = data;
136 struct kprobe *p = args->p;
137 u16 opc;
138
139 opc = args->arm_kprobe ? BREAKPOINT_INSTRUCTION : p->opcode;
140 s390_kernel_write(p->addr, &opc, sizeof(opc));
141 return 0;
142}
143NOKPROBE_SYMBOL(swap_instruction);
144
145void arch_arm_kprobe(struct kprobe *p)
146{
147 struct swap_insn_args args = {.p = p, .arm_kprobe = 1};
148
149 stop_machine_cpuslocked(swap_instruction, &args, NULL);
150}
151NOKPROBE_SYMBOL(arch_arm_kprobe);
152
153void arch_disarm_kprobe(struct kprobe *p)
154{
155 struct swap_insn_args args = {.p = p, .arm_kprobe = 0};
156
157 stop_machine_cpuslocked(swap_instruction, &args, NULL);
158}
159NOKPROBE_SYMBOL(arch_disarm_kprobe);
160
161void arch_remove_kprobe(struct kprobe *p)
162{
163 s390_free_insn_slot(p);
164}
165NOKPROBE_SYMBOL(arch_remove_kprobe);
166
167static void enable_singlestep(struct kprobe_ctlblk *kcb,
168 struct pt_regs *regs,
169 unsigned long ip)
170{
171 struct per_regs per_kprobe;
172
173
174 per_kprobe.control = PER_EVENT_IFETCH;
175 per_kprobe.start = ip;
176 per_kprobe.end = ip;
177
178
179 __ctl_store(kcb->kprobe_saved_ctl, 9, 11);
180 kcb->kprobe_saved_imask = regs->psw.mask &
181 (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT);
182
183
184 __ctl_load(per_kprobe, 9, 11);
185 regs->psw.mask |= PSW_MASK_PER;
186 regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT);
187 regs->psw.addr = ip;
188}
189NOKPROBE_SYMBOL(enable_singlestep);
190
191static void disable_singlestep(struct kprobe_ctlblk *kcb,
192 struct pt_regs *regs,
193 unsigned long ip)
194{
195
196 __ctl_load(kcb->kprobe_saved_ctl, 9, 11);
197 regs->psw.mask &= ~PSW_MASK_PER;
198 regs->psw.mask |= kcb->kprobe_saved_imask;
199 regs->psw.addr = ip;
200}
201NOKPROBE_SYMBOL(disable_singlestep);
202
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206
207
208static void push_kprobe(struct kprobe_ctlblk *kcb, struct kprobe *p)
209{
210 kcb->prev_kprobe.kp = __this_cpu_read(current_kprobe);
211 kcb->prev_kprobe.status = kcb->kprobe_status;
212 __this_cpu_write(current_kprobe, p);
213}
214NOKPROBE_SYMBOL(push_kprobe);
215
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218
219
220
221static void pop_kprobe(struct kprobe_ctlblk *kcb)
222{
223 __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
224 kcb->kprobe_status = kcb->prev_kprobe.status;
225}
226NOKPROBE_SYMBOL(pop_kprobe);
227
228void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs)
229{
230 ri->ret_addr = (kprobe_opcode_t *) regs->gprs[14];
231
232
233 regs->gprs[14] = (unsigned long) &kretprobe_trampoline;
234}
235NOKPROBE_SYMBOL(arch_prepare_kretprobe);
236
237static void kprobe_reenter_check(struct kprobe_ctlblk *kcb, struct kprobe *p)
238{
239 switch (kcb->kprobe_status) {
240 case KPROBE_HIT_SSDONE:
241 case KPROBE_HIT_ACTIVE:
242 kprobes_inc_nmissed_count(p);
243 break;
244 case KPROBE_HIT_SS:
245 case KPROBE_REENTER:
246 default:
247
248
249
250
251
252 pr_err("Invalid kprobe detected.\n");
253 dump_kprobe(p);
254 BUG();
255 }
256}
257NOKPROBE_SYMBOL(kprobe_reenter_check);
258
259static int kprobe_handler(struct pt_regs *regs)
260{
261 struct kprobe_ctlblk *kcb;
262 struct kprobe *p;
263
264
265
266
267
268
269 preempt_disable();
270 kcb = get_kprobe_ctlblk();
271 p = get_kprobe((void *)(regs->psw.addr - 2));
272
273 if (p) {
274 if (kprobe_running()) {
275
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282
283
284 kprobe_reenter_check(kcb, p);
285 push_kprobe(kcb, p);
286 kcb->kprobe_status = KPROBE_REENTER;
287 } else {
288
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293
294
295 push_kprobe(kcb, p);
296 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
297 if (p->pre_handler && p->pre_handler(p, regs)) {
298 pop_kprobe(kcb);
299 preempt_enable_no_resched();
300 return 1;
301 }
302 kcb->kprobe_status = KPROBE_HIT_SS;
303 }
304 enable_singlestep(kcb, regs, (unsigned long) p->ainsn.insn);
305 return 1;
306 }
307
308
309
310
311
312 preempt_enable_no_resched();
313 return 0;
314}
315NOKPROBE_SYMBOL(kprobe_handler);
316
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321
322
323static void __used kretprobe_trampoline_holder(void)
324{
325 asm volatile(".global kretprobe_trampoline\n"
326 "kretprobe_trampoline: bcr 0,0\n");
327}
328
329
330
331
332static int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
333{
334 struct kretprobe_instance *ri;
335 struct hlist_head *head, empty_rp;
336 struct hlist_node *tmp;
337 unsigned long flags, orig_ret_address;
338 unsigned long trampoline_address;
339 kprobe_opcode_t *correct_ret_addr;
340
341 INIT_HLIST_HEAD(&empty_rp);
342 kretprobe_hash_lock(current, &head, &flags);
343
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355
356
357 ri = NULL;
358 orig_ret_address = 0;
359 correct_ret_addr = NULL;
360 trampoline_address = (unsigned long) &kretprobe_trampoline;
361 hlist_for_each_entry_safe(ri, tmp, head, hlist) {
362 if (ri->task != current)
363
364 continue;
365
366 orig_ret_address = (unsigned long) ri->ret_addr;
367
368 if (orig_ret_address != trampoline_address)
369
370
371
372
373
374 break;
375 }
376
377 kretprobe_assert(ri, orig_ret_address, trampoline_address);
378
379 correct_ret_addr = ri->ret_addr;
380 hlist_for_each_entry_safe(ri, tmp, head, hlist) {
381 if (ri->task != current)
382
383 continue;
384
385 orig_ret_address = (unsigned long) ri->ret_addr;
386
387 if (ri->rp && ri->rp->handler) {
388 ri->ret_addr = correct_ret_addr;
389 ri->rp->handler(ri, regs);
390 }
391
392 recycle_rp_inst(ri, &empty_rp);
393
394 if (orig_ret_address != trampoline_address)
395
396
397
398
399
400 break;
401 }
402
403 regs->psw.addr = orig_ret_address;
404
405 kretprobe_hash_unlock(current, &flags);
406
407 hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
408 hlist_del(&ri->hlist);
409 kfree(ri);
410 }
411
412
413
414
415
416 return 1;
417}
418NOKPROBE_SYMBOL(trampoline_probe_handler);
419
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425
426
427
428static void resume_execution(struct kprobe *p, struct pt_regs *regs)
429{
430 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
431 unsigned long ip = regs->psw.addr;
432 int fixup = probe_get_fixup_type(p->ainsn.insn);
433
434 if (fixup & FIXUP_PSW_NORMAL)
435 ip += (unsigned long) p->addr - (unsigned long) p->ainsn.insn;
436
437 if (fixup & FIXUP_BRANCH_NOT_TAKEN) {
438 int ilen = insn_length(p->ainsn.insn[0] >> 8);
439 if (ip - (unsigned long) p->ainsn.insn == ilen)
440 ip = (unsigned long) p->addr + ilen;
441 }
442
443 if (fixup & FIXUP_RETURN_REGISTER) {
444 int reg = (p->ainsn.insn[0] & 0xf0) >> 4;
445 regs->gprs[reg] += (unsigned long) p->addr -
446 (unsigned long) p->ainsn.insn;
447 }
448
449 disable_singlestep(kcb, regs, ip);
450}
451NOKPROBE_SYMBOL(resume_execution);
452
453static int post_kprobe_handler(struct pt_regs *regs)
454{
455 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
456 struct kprobe *p = kprobe_running();
457
458 if (!p)
459 return 0;
460
461 if (kcb->kprobe_status != KPROBE_REENTER && p->post_handler) {
462 kcb->kprobe_status = KPROBE_HIT_SSDONE;
463 p->post_handler(p, regs, 0);
464 }
465
466 resume_execution(p, regs);
467 pop_kprobe(kcb);
468 preempt_enable_no_resched();
469
470
471
472
473
474
475 if (regs->psw.mask & PSW_MASK_PER)
476 return 0;
477
478 return 1;
479}
480NOKPROBE_SYMBOL(post_kprobe_handler);
481
482static int kprobe_trap_handler(struct pt_regs *regs, int trapnr)
483{
484 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
485 struct kprobe *p = kprobe_running();
486 const struct exception_table_entry *entry;
487
488 switch(kcb->kprobe_status) {
489 case KPROBE_HIT_SS:
490 case KPROBE_REENTER:
491
492
493
494
495
496
497
498 disable_singlestep(kcb, regs, (unsigned long) p->addr);
499 pop_kprobe(kcb);
500 preempt_enable_no_resched();
501 break;
502 case KPROBE_HIT_ACTIVE:
503 case KPROBE_HIT_SSDONE:
504
505
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507
508
509 kprobes_inc_nmissed_count(p);
510
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515
516
517
518 if (p->fault_handler && p->fault_handler(p, regs, trapnr))
519 return 1;
520
521
522
523
524
525 entry = s390_search_extables(regs->psw.addr);
526 if (entry && ex_handle(entry, regs))
527 return 1;
528
529
530
531
532
533 break;
534 default:
535 break;
536 }
537 return 0;
538}
539NOKPROBE_SYMBOL(kprobe_trap_handler);
540
541int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
542{
543 int ret;
544
545 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
546 local_irq_disable();
547 ret = kprobe_trap_handler(regs, trapnr);
548 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
549 local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
550 return ret;
551}
552NOKPROBE_SYMBOL(kprobe_fault_handler);
553
554
555
556
557int kprobe_exceptions_notify(struct notifier_block *self,
558 unsigned long val, void *data)
559{
560 struct die_args *args = (struct die_args *) data;
561 struct pt_regs *regs = args->regs;
562 int ret = NOTIFY_DONE;
563
564 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
565 local_irq_disable();
566
567 switch (val) {
568 case DIE_BPT:
569 if (kprobe_handler(regs))
570 ret = NOTIFY_STOP;
571 break;
572 case DIE_SSTEP:
573 if (post_kprobe_handler(regs))
574 ret = NOTIFY_STOP;
575 break;
576 case DIE_TRAP:
577 if (!preemptible() && kprobe_running() &&
578 kprobe_trap_handler(regs, args->trapnr))
579 ret = NOTIFY_STOP;
580 break;
581 default:
582 break;
583 }
584
585 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
586 local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
587
588 return ret;
589}
590NOKPROBE_SYMBOL(kprobe_exceptions_notify);
591
592static struct kprobe trampoline = {
593 .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
594 .pre_handler = trampoline_probe_handler
595};
596
597int __init arch_init_kprobes(void)
598{
599 return register_kprobe(&trampoline);
600}
601
602int arch_trampoline_kprobe(struct kprobe *p)
603{
604 return p->addr == (kprobe_opcode_t *) &kretprobe_trampoline;
605}
606NOKPROBE_SYMBOL(arch_trampoline_kprobe);
607