1
2
3
4
5
6
7#include <linux/kernel.h>
8#include <linux/kprobes.h>
9#include <linux/extable.h>
10#include <linux/kdebug.h>
11#include <linux/slab.h>
12#include <linux/context_tracking.h>
13#include <asm/signal.h>
14#include <asm/cacheflush.h>
15#include <linux/uaccess.h>
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
46DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
47
48struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
49
50int __kprobes arch_prepare_kprobe(struct kprobe *p)
51{
52 if ((unsigned long) p->addr & 0x3UL)
53 return -EILSEQ;
54
55 p->ainsn.insn[0] = *p->addr;
56 flushi(&p->ainsn.insn[0]);
57
58 p->ainsn.insn[1] = BREAKPOINT_INSTRUCTION_2;
59 flushi(&p->ainsn.insn[1]);
60
61 p->opcode = *p->addr;
62 return 0;
63}
64
65void __kprobes arch_arm_kprobe(struct kprobe *p)
66{
67 *p->addr = BREAKPOINT_INSTRUCTION;
68 flushi(p->addr);
69}
70
71void __kprobes arch_disarm_kprobe(struct kprobe *p)
72{
73 *p->addr = p->opcode;
74 flushi(p->addr);
75}
76
77static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
78{
79 kcb->prev_kprobe.kp = kprobe_running();
80 kcb->prev_kprobe.status = kcb->kprobe_status;
81 kcb->prev_kprobe.orig_tnpc = kcb->kprobe_orig_tnpc;
82 kcb->prev_kprobe.orig_tstate_pil = kcb->kprobe_orig_tstate_pil;
83}
84
85static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
86{
87 __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
88 kcb->kprobe_status = kcb->prev_kprobe.status;
89 kcb->kprobe_orig_tnpc = kcb->prev_kprobe.orig_tnpc;
90 kcb->kprobe_orig_tstate_pil = kcb->prev_kprobe.orig_tstate_pil;
91}
92
93static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
94 struct kprobe_ctlblk *kcb)
95{
96 __this_cpu_write(current_kprobe, p);
97 kcb->kprobe_orig_tnpc = regs->tnpc;
98 kcb->kprobe_orig_tstate_pil = (regs->tstate & TSTATE_PIL);
99}
100
101static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs,
102 struct kprobe_ctlblk *kcb)
103{
104 regs->tstate |= TSTATE_PIL;
105
106
107 if (p->opcode == BREAKPOINT_INSTRUCTION) {
108 regs->tpc = (unsigned long) p->addr;
109 regs->tnpc = kcb->kprobe_orig_tnpc;
110 } else {
111 regs->tpc = (unsigned long) &p->ainsn.insn[0];
112 regs->tnpc = (unsigned long) &p->ainsn.insn[1];
113 }
114}
115
116static int __kprobes kprobe_handler(struct pt_regs *regs)
117{
118 struct kprobe *p;
119 void *addr = (void *) regs->tpc;
120 int ret = 0;
121 struct kprobe_ctlblk *kcb;
122
123
124
125
126
127 preempt_disable();
128 kcb = get_kprobe_ctlblk();
129
130 if (kprobe_running()) {
131 p = get_kprobe(addr);
132 if (p) {
133 if (kcb->kprobe_status == KPROBE_HIT_SS) {
134 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
135 kcb->kprobe_orig_tstate_pil);
136 goto no_kprobe;
137 }
138
139
140
141
142
143
144 save_previous_kprobe(kcb);
145 set_current_kprobe(p, regs, kcb);
146 kprobes_inc_nmissed_count(p);
147 kcb->kprobe_status = KPROBE_REENTER;
148 prepare_singlestep(p, regs, kcb);
149 return 1;
150 } else if (*(u32 *)addr != BREAKPOINT_INSTRUCTION) {
151
152
153
154
155 ret = 1;
156 }
157 goto no_kprobe;
158 }
159
160 p = get_kprobe(addr);
161 if (!p) {
162 if (*(u32 *)addr != BREAKPOINT_INSTRUCTION) {
163
164
165
166
167
168
169
170 ret = 1;
171 }
172
173 goto no_kprobe;
174 }
175
176 set_current_kprobe(p, regs, kcb);
177 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
178 if (p->pre_handler && p->pre_handler(p, regs)) {
179 reset_current_kprobe();
180 preempt_enable_no_resched();
181 return 1;
182 }
183
184 prepare_singlestep(p, regs, kcb);
185 kcb->kprobe_status = KPROBE_HIT_SS;
186 return 1;
187
188no_kprobe:
189 preempt_enable_no_resched();
190 return ret;
191}
192
193
194
195
196
197
198
199
200
201static unsigned long __kprobes relbranch_fixup(u32 insn, struct kprobe *p,
202 struct pt_regs *regs)
203{
204 unsigned long real_pc = (unsigned long) p->addr;
205
206
207 if (regs->tnpc == regs->tpc + 0x4UL)
208 return real_pc + 0x8UL;
209
210
211
212
213 if ((insn & 0xc0000000) == 0x40000000 ||
214 (insn & 0xc1c00000) == 0x00400000 ||
215 (insn & 0xc1c00000) == 0x00800000) {
216 unsigned long ainsn_addr;
217
218 ainsn_addr = (unsigned long) &p->ainsn.insn[0];
219
220
221
222
223
224 return (real_pc + (regs->tnpc - ainsn_addr));
225 }
226
227
228
229
230 return regs->tnpc;
231}
232
233
234
235
236static void __kprobes retpc_fixup(struct pt_regs *regs, u32 insn,
237 unsigned long real_pc)
238{
239 unsigned long *slot = NULL;
240
241
242 if ((insn & 0xc0000000) == 0x40000000) {
243 slot = ®s->u_regs[UREG_I7];
244 }
245
246
247 if ((insn & 0xc1f80000) == 0x81c00000) {
248 unsigned long rd = ((insn >> 25) & 0x1f);
249
250 if (rd <= 15) {
251 slot = ®s->u_regs[rd];
252 } else {
253
254 flushw_all();
255
256 rd -= 16;
257 slot = (unsigned long *)
258 (regs->u_regs[UREG_FP] + STACK_BIAS);
259 slot += rd;
260 }
261 }
262 if (slot != NULL)
263 *slot = real_pc;
264}
265
266
267
268
269
270
271
272
273
274
275
276
277static void __kprobes resume_execution(struct kprobe *p,
278 struct pt_regs *regs, struct kprobe_ctlblk *kcb)
279{
280 u32 insn = p->ainsn.insn[0];
281
282 regs->tnpc = relbranch_fixup(insn, p, regs);
283
284
285 regs->tpc = kcb->kprobe_orig_tnpc;
286
287 retpc_fixup(regs, insn, (unsigned long) p->addr);
288
289 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
290 kcb->kprobe_orig_tstate_pil);
291}
292
293static int __kprobes post_kprobe_handler(struct pt_regs *regs)
294{
295 struct kprobe *cur = kprobe_running();
296 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
297
298 if (!cur)
299 return 0;
300
301 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
302 kcb->kprobe_status = KPROBE_HIT_SSDONE;
303 cur->post_handler(cur, regs, 0);
304 }
305
306 resume_execution(cur, regs, kcb);
307
308
309 if (kcb->kprobe_status == KPROBE_REENTER) {
310 restore_previous_kprobe(kcb);
311 goto out;
312 }
313 reset_current_kprobe();
314out:
315 preempt_enable_no_resched();
316
317 return 1;
318}
319
320int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
321{
322 struct kprobe *cur = kprobe_running();
323 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
324 const struct exception_table_entry *entry;
325
326 switch(kcb->kprobe_status) {
327 case KPROBE_HIT_SS:
328 case KPROBE_REENTER:
329
330
331
332
333
334
335
336 regs->tpc = (unsigned long)cur->addr;
337 regs->tnpc = kcb->kprobe_orig_tnpc;
338 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
339 kcb->kprobe_orig_tstate_pil);
340 if (kcb->kprobe_status == KPROBE_REENTER)
341 restore_previous_kprobe(kcb);
342 else
343 reset_current_kprobe();
344 preempt_enable_no_resched();
345 break;
346 case KPROBE_HIT_ACTIVE:
347 case KPROBE_HIT_SSDONE:
348
349
350
351
352
353 entry = search_exception_tables(regs->tpc);
354 if (entry) {
355 regs->tpc = entry->fixup;
356 regs->tnpc = regs->tpc + 4;
357 return 1;
358 }
359
360
361
362
363
364 break;
365 default:
366 break;
367 }
368
369 return 0;
370}
371
372
373
374
375int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
376 unsigned long val, void *data)
377{
378 struct die_args *args = (struct die_args *)data;
379 int ret = NOTIFY_DONE;
380
381 if (args->regs && user_mode(args->regs))
382 return ret;
383
384 switch (val) {
385 case DIE_DEBUG:
386 if (kprobe_handler(args->regs))
387 ret = NOTIFY_STOP;
388 break;
389 case DIE_DEBUG_2:
390 if (post_kprobe_handler(args->regs))
391 ret = NOTIFY_STOP;
392 break;
393 default:
394 break;
395 }
396 return ret;
397}
398
399asmlinkage void __kprobes kprobe_trap(unsigned long trap_level,
400 struct pt_regs *regs)
401{
402 enum ctx_state prev_state = exception_enter();
403
404 BUG_ON(trap_level != 0x170 && trap_level != 0x171);
405
406 if (user_mode(regs)) {
407 local_irq_enable();
408 bad_trap(regs, trap_level);
409 goto out;
410 }
411
412
413
414
415 if (notify_die((trap_level == 0x170) ? DIE_DEBUG : DIE_DEBUG_2,
416 (trap_level == 0x170) ? "debug" : "debug_2",
417 regs, 0, trap_level, SIGTRAP) != NOTIFY_STOP)
418 bad_trap(regs, trap_level);
419out:
420 exception_exit(prev_state);
421}
422
423
424
425
426
427
428
429
430
431
432
433
434
435void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
436 struct pt_regs *regs)
437{
438 ri->ret_addr = (kprobe_opcode_t *)(regs->u_regs[UREG_RETPC] + 8);
439 ri->fp = NULL;
440
441
442 regs->u_regs[UREG_RETPC] =
443 ((unsigned long)kretprobe_trampoline) - 8;
444}
445
446
447
448
449static int __kprobes trampoline_probe_handler(struct kprobe *p,
450 struct pt_regs *regs)
451{
452 unsigned long orig_ret_address = 0;
453
454 orig_ret_address = __kretprobe_trampoline_handler(regs, &kretprobe_trampoline, NULL);
455 regs->tpc = orig_ret_address;
456 regs->tnpc = orig_ret_address + 4;
457
458
459
460
461
462
463 return 1;
464}
465
466static void __used kretprobe_trampoline_holder(void)
467{
468 asm volatile(".global kretprobe_trampoline\n"
469 "kretprobe_trampoline:\n"
470 "\tnop\n"
471 "\tnop\n");
472}
473static struct kprobe trampoline_p = {
474 .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
475 .pre_handler = trampoline_probe_handler
476};
477
478int __init arch_init_kprobes(void)
479{
480 return register_kprobe(&trampoline_p);
481}
482
483int __kprobes arch_trampoline_kprobe(struct kprobe *p)
484{
485 if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
486 return 1;
487
488 return 0;
489}
490