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16#include <linux/kprobes.h>
17#include <linux/ptrace.h>
18#include <linux/preempt.h>
19#include <linux/extable.h>
20#include <linux/kdebug.h>
21#include <linux/slab.h>
22#include <linux/moduleloader.h>
23#include <asm/code-patching.h>
24#include <asm/cacheflush.h>
25#include <asm/sstep.h>
26#include <asm/sections.h>
27#include <asm/inst.h>
28#include <asm/set_memory.h>
29#include <linux/uaccess.h>
30
31DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
32DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
33
34struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
35
36bool arch_within_kprobe_blacklist(unsigned long addr)
37{
38 return (addr >= (unsigned long)__kprobes_text_start &&
39 addr < (unsigned long)__kprobes_text_end) ||
40 (addr >= (unsigned long)_stext &&
41 addr < (unsigned long)__head_end);
42}
43
44kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset)
45{
46 kprobe_opcode_t *addr = NULL;
47
48#ifdef PPC64_ELF_ABI_v2
49
50 addr = (kprobe_opcode_t *)kallsyms_lookup_name(name);
51 if (addr && !offset) {
52#ifdef CONFIG_KPROBES_ON_FTRACE
53 unsigned long faddr;
54
55
56
57
58 faddr = ftrace_location_range((unsigned long)addr,
59 (unsigned long)addr + 16);
60 if (faddr)
61 addr = (kprobe_opcode_t *)faddr;
62 else
63#endif
64 addr = (kprobe_opcode_t *)ppc_function_entry(addr);
65 }
66#elif defined(PPC64_ELF_ABI_v1)
67
68
69
70
71
72
73
74
75
76
77 char dot_name[MODULE_NAME_LEN + 1 + KSYM_NAME_LEN];
78 bool dot_appended = false;
79 const char *c;
80 ssize_t ret = 0;
81 int len = 0;
82
83 if ((c = strnchr(name, MODULE_NAME_LEN, ':')) != NULL) {
84 c++;
85 len = c - name;
86 memcpy(dot_name, name, len);
87 } else
88 c = name;
89
90 if (*c != '\0' && *c != '.') {
91 dot_name[len++] = '.';
92 dot_appended = true;
93 }
94 ret = strscpy(dot_name + len, c, KSYM_NAME_LEN);
95 if (ret > 0)
96 addr = (kprobe_opcode_t *)kallsyms_lookup_name(dot_name);
97
98
99 if (!addr && dot_appended)
100 addr = (kprobe_opcode_t *)kallsyms_lookup_name(name);
101#else
102 addr = (kprobe_opcode_t *)kallsyms_lookup_name(name);
103#endif
104
105 return addr;
106}
107
108void *alloc_insn_page(void)
109{
110 void *page;
111
112 page = module_alloc(PAGE_SIZE);
113 if (!page)
114 return NULL;
115
116 if (strict_module_rwx_enabled()) {
117 set_memory_ro((unsigned long)page, 1);
118 set_memory_x((unsigned long)page, 1);
119 }
120 return page;
121}
122
123int arch_prepare_kprobe(struct kprobe *p)
124{
125 int ret = 0;
126 struct kprobe *prev;
127 struct ppc_inst insn = ppc_inst_read(p->addr);
128
129 if ((unsigned long)p->addr & 0x03) {
130 printk("Attempt to register kprobe at an unaligned address\n");
131 ret = -EINVAL;
132 } else if (IS_MTMSRD(insn) || IS_RFID(insn)) {
133 printk("Cannot register a kprobe on mtmsr[d]/rfi[d]\n");
134 ret = -EINVAL;
135 } else if ((unsigned long)p->addr & ~PAGE_MASK &&
136 ppc_inst_prefixed(ppc_inst_read(p->addr - 1))) {
137 printk("Cannot register a kprobe on the second word of prefixed instruction\n");
138 ret = -EINVAL;
139 }
140 preempt_disable();
141 prev = get_kprobe(p->addr - 1);
142 preempt_enable_no_resched();
143 if (prev && ppc_inst_prefixed(ppc_inst_read(prev->ainsn.insn))) {
144 printk("Cannot register a kprobe on the second word of prefixed instruction\n");
145 ret = -EINVAL;
146 }
147
148
149
150 if (!ret) {
151 p->ainsn.insn = get_insn_slot();
152 if (!p->ainsn.insn)
153 ret = -ENOMEM;
154 }
155
156 if (!ret) {
157 patch_instruction(p->ainsn.insn, insn);
158 p->opcode = ppc_inst_val(insn);
159 }
160
161 p->ainsn.boostable = 0;
162 return ret;
163}
164NOKPROBE_SYMBOL(arch_prepare_kprobe);
165
166void arch_arm_kprobe(struct kprobe *p)
167{
168 WARN_ON_ONCE(patch_instruction(p->addr, ppc_inst(BREAKPOINT_INSTRUCTION)));
169}
170NOKPROBE_SYMBOL(arch_arm_kprobe);
171
172void arch_disarm_kprobe(struct kprobe *p)
173{
174 WARN_ON_ONCE(patch_instruction(p->addr, ppc_inst(p->opcode)));
175}
176NOKPROBE_SYMBOL(arch_disarm_kprobe);
177
178void arch_remove_kprobe(struct kprobe *p)
179{
180 if (p->ainsn.insn) {
181 free_insn_slot(p->ainsn.insn, 0);
182 p->ainsn.insn = NULL;
183 }
184}
185NOKPROBE_SYMBOL(arch_remove_kprobe);
186
187static nokprobe_inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
188{
189 enable_single_step(regs);
190
191
192
193
194
195
196
197 regs_set_return_ip(regs, (unsigned long)p->ainsn.insn);
198}
199
200static nokprobe_inline void save_previous_kprobe(struct kprobe_ctlblk *kcb)
201{
202 kcb->prev_kprobe.kp = kprobe_running();
203 kcb->prev_kprobe.status = kcb->kprobe_status;
204 kcb->prev_kprobe.saved_msr = kcb->kprobe_saved_msr;
205}
206
207static nokprobe_inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
208{
209 __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
210 kcb->kprobe_status = kcb->prev_kprobe.status;
211 kcb->kprobe_saved_msr = kcb->prev_kprobe.saved_msr;
212}
213
214static nokprobe_inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
215 struct kprobe_ctlblk *kcb)
216{
217 __this_cpu_write(current_kprobe, p);
218 kcb->kprobe_saved_msr = regs->msr;
219}
220
221bool arch_kprobe_on_func_entry(unsigned long offset)
222{
223#ifdef PPC64_ELF_ABI_v2
224#ifdef CONFIG_KPROBES_ON_FTRACE
225 return offset <= 16;
226#else
227 return offset <= 8;
228#endif
229#else
230 return !offset;
231#endif
232}
233
234void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs)
235{
236 ri->ret_addr = (kprobe_opcode_t *)regs->link;
237 ri->fp = NULL;
238
239
240 regs->link = (unsigned long)kretprobe_trampoline;
241}
242NOKPROBE_SYMBOL(arch_prepare_kretprobe);
243
244static int try_to_emulate(struct kprobe *p, struct pt_regs *regs)
245{
246 int ret;
247 struct ppc_inst insn = ppc_inst_read(p->ainsn.insn);
248
249
250 ret = emulate_step(regs, insn);
251 if (ret > 0) {
252
253
254
255
256 if (unlikely(p->ainsn.boostable == 0))
257 p->ainsn.boostable = 1;
258 } else if (ret < 0) {
259
260
261
262
263
264 printk("Can't step on instruction %s\n", ppc_inst_as_str(insn));
265 BUG();
266 } else {
267
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275
276
277 if (unlikely(p->ainsn.boostable != 1))
278 p->ainsn.boostable = -1;
279 }
280
281 return ret;
282}
283NOKPROBE_SYMBOL(try_to_emulate);
284
285int kprobe_handler(struct pt_regs *regs)
286{
287 struct kprobe *p;
288 int ret = 0;
289 unsigned int *addr = (unsigned int *)regs->nip;
290 struct kprobe_ctlblk *kcb;
291
292 if (user_mode(regs))
293 return 0;
294
295 if (!IS_ENABLED(CONFIG_BOOKE) &&
296 (!(regs->msr & MSR_IR) || !(regs->msr & MSR_DR)))
297 return 0;
298
299
300
301
302
303 preempt_disable();
304 kcb = get_kprobe_ctlblk();
305
306 p = get_kprobe(addr);
307 if (!p) {
308 unsigned int instr;
309
310 if (get_kernel_nofault(instr, addr))
311 goto no_kprobe;
312
313 if (instr != BREAKPOINT_INSTRUCTION) {
314
315
316
317
318
319 if (is_trap(instr))
320 goto no_kprobe;
321
322
323
324
325
326
327
328 ret = 1;
329 }
330
331 goto no_kprobe;
332 }
333
334
335 if (kprobe_running()) {
336 kprobe_opcode_t insn = *p->ainsn.insn;
337 if (kcb->kprobe_status == KPROBE_HIT_SS && is_trap(insn)) {
338
339 regs_set_return_msr(regs,
340 (regs->msr & ~MSR_SINGLESTEP) |
341 kcb->kprobe_saved_msr);
342 goto no_kprobe;
343 }
344
345
346
347
348
349
350
351 save_previous_kprobe(kcb);
352 set_current_kprobe(p, regs, kcb);
353 kprobes_inc_nmissed_count(p);
354 kcb->kprobe_status = KPROBE_REENTER;
355 if (p->ainsn.boostable >= 0) {
356 ret = try_to_emulate(p, regs);
357
358 if (ret > 0) {
359 restore_previous_kprobe(kcb);
360 preempt_enable_no_resched();
361 return 1;
362 }
363 }
364 prepare_singlestep(p, regs);
365 return 1;
366 }
367
368 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
369 set_current_kprobe(p, regs, kcb);
370 if (p->pre_handler && p->pre_handler(p, regs)) {
371
372 reset_current_kprobe();
373 preempt_enable_no_resched();
374 return 1;
375 }
376
377 if (p->ainsn.boostable >= 0) {
378 ret = try_to_emulate(p, regs);
379
380 if (ret > 0) {
381 if (p->post_handler)
382 p->post_handler(p, regs, 0);
383
384 kcb->kprobe_status = KPROBE_HIT_SSDONE;
385 reset_current_kprobe();
386 preempt_enable_no_resched();
387 return 1;
388 }
389 }
390 prepare_singlestep(p, regs);
391 kcb->kprobe_status = KPROBE_HIT_SS;
392 return 1;
393
394no_kprobe:
395 preempt_enable_no_resched();
396 return ret;
397}
398NOKPROBE_SYMBOL(kprobe_handler);
399
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401
402
403
404
405
406asm(".global kretprobe_trampoline\n"
407 ".type kretprobe_trampoline, @function\n"
408 "kretprobe_trampoline:\n"
409 "nop\n"
410 "blr\n"
411 ".size kretprobe_trampoline, .-kretprobe_trampoline\n");
412
413
414
415
416static int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
417{
418 unsigned long orig_ret_address;
419
420 orig_ret_address = __kretprobe_trampoline_handler(regs, &kretprobe_trampoline, NULL);
421
422
423
424
425
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428
429
430
431
432
433
434
435
436 regs_set_return_ip(regs, orig_ret_address - 4);
437 regs->link = orig_ret_address;
438
439 return 0;
440}
441NOKPROBE_SYMBOL(trampoline_probe_handler);
442
443
444
445
446
447
448
449
450
451int kprobe_post_handler(struct pt_regs *regs)
452{
453 int len;
454 struct kprobe *cur = kprobe_running();
455 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
456
457 if (!cur || user_mode(regs))
458 return 0;
459
460 len = ppc_inst_len(ppc_inst_read(cur->ainsn.insn));
461
462 if (((unsigned long)cur->ainsn.insn + len) != regs->nip)
463 return 0;
464
465 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
466 kcb->kprobe_status = KPROBE_HIT_SSDONE;
467 cur->post_handler(cur, regs, 0);
468 }
469
470
471 regs_set_return_ip(regs, (unsigned long)cur->addr + len);
472 regs_set_return_msr(regs, regs->msr | kcb->kprobe_saved_msr);
473
474
475 if (kcb->kprobe_status == KPROBE_REENTER) {
476 restore_previous_kprobe(kcb);
477 goto out;
478 }
479 reset_current_kprobe();
480out:
481 preempt_enable_no_resched();
482
483
484
485
486
487
488 if (regs->msr & MSR_SINGLESTEP)
489 return 0;
490
491 return 1;
492}
493NOKPROBE_SYMBOL(kprobe_post_handler);
494
495int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
496{
497 struct kprobe *cur = kprobe_running();
498 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
499 const struct exception_table_entry *entry;
500
501 switch(kcb->kprobe_status) {
502 case KPROBE_HIT_SS:
503 case KPROBE_REENTER:
504
505
506
507
508
509
510
511 regs_set_return_ip(regs, (unsigned long)cur->addr);
512
513 regs_set_return_msr(regs,
514 (regs->msr & ~MSR_SINGLESTEP) |
515 kcb->kprobe_saved_msr);
516 if (kcb->kprobe_status == KPROBE_REENTER)
517 restore_previous_kprobe(kcb);
518 else
519 reset_current_kprobe();
520 preempt_enable_no_resched();
521 break;
522 case KPROBE_HIT_ACTIVE:
523 case KPROBE_HIT_SSDONE:
524
525
526
527
528 if ((entry = search_exception_tables(regs->nip)) != NULL) {
529 regs_set_return_ip(regs, extable_fixup(entry));
530 return 1;
531 }
532
533
534
535
536
537 break;
538 default:
539 break;
540 }
541 return 0;
542}
543NOKPROBE_SYMBOL(kprobe_fault_handler);
544
545unsigned long arch_deref_entry_point(void *entry)
546{
547#ifdef PPC64_ELF_ABI_v1
548 if (!kernel_text_address((unsigned long)entry))
549 return ppc_global_function_entry(entry);
550 else
551#endif
552 return (unsigned long)entry;
553}
554NOKPROBE_SYMBOL(arch_deref_entry_point);
555
556static struct kprobe trampoline_p = {
557 .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
558 .pre_handler = trampoline_probe_handler
559};
560
561int __init arch_init_kprobes(void)
562{
563 return register_kprobe(&trampoline_p);
564}
565
566int arch_trampoline_kprobe(struct kprobe *p)
567{
568 if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
569 return 1;
570
571 return 0;
572}
573NOKPROBE_SYMBOL(arch_trampoline_kprobe);
574