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1/*
2 * Kernel probes (kprobes) for SuperH
3 *
4 * Copyright (C) 2007 Chris Smith <chris.smith@st.com>
5 * Copyright (C) 2006 Lineo Solutions, Inc.
6 *
7 * This file is subject to the terms and conditions of the GNU General Public
8 * License. See the file "COPYING" in the main directory of this archive
9 * for more details.
10 */
11#include <linux/kprobes.h>
12#include <linux/module.h>
13#include <linux/ptrace.h>
14#include <linux/preempt.h>
15#include <linux/kdebug.h>
16#include <linux/slab.h>
17#include <asm/cacheflush.h>
18#include <asm/uaccess.h>
19
20DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
21DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
22
23static DEFINE_PER_CPU(struct kprobe, saved_current_opcode);
24static DEFINE_PER_CPU(struct kprobe, saved_next_opcode);
25static DEFINE_PER_CPU(struct kprobe, saved_next_opcode2);
26
27#define OPCODE_JMP(x) (((x) & 0xF0FF) == 0x402b)
28#define OPCODE_JSR(x) (((x) & 0xF0FF) == 0x400b)
29#define OPCODE_BRA(x) (((x) & 0xF000) == 0xa000)
30#define OPCODE_BRAF(x) (((x) & 0xF0FF) == 0x0023)
31#define OPCODE_BSR(x) (((x) & 0xF000) == 0xb000)
32#define OPCODE_BSRF(x) (((x) & 0xF0FF) == 0x0003)
33
34#define OPCODE_BF_S(x) (((x) & 0xFF00) == 0x8f00)
35#define OPCODE_BT_S(x) (((x) & 0xFF00) == 0x8d00)
36
37#define OPCODE_BF(x) (((x) & 0xFF00) == 0x8b00)
38#define OPCODE_BT(x) (((x) & 0xFF00) == 0x8900)
39
40#define OPCODE_RTS(x) (((x) & 0x000F) == 0x000b)
41#define OPCODE_RTE(x) (((x) & 0xFFFF) == 0x002b)
42
43int __kprobes arch_prepare_kprobe(struct kprobe *p)
44{
45 kprobe_opcode_t opcode = *(kprobe_opcode_t *) (p->addr);
46
47 if (OPCODE_RTE(opcode))
48 return -EFAULT; /* Bad breakpoint */
49
50 p->opcode = opcode;
51
52 return 0;
53}
54
55void __kprobes arch_copy_kprobe(struct kprobe *p)
56{
57 memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
58 p->opcode = *p->addr;
59}
60
61void __kprobes arch_arm_kprobe(struct kprobe *p)
62{
63 *p->addr = BREAKPOINT_INSTRUCTION;
64 flush_icache_range((unsigned long)p->addr,
65 (unsigned long)p->addr + sizeof(kprobe_opcode_t));
66}
67
68void __kprobes arch_disarm_kprobe(struct kprobe *p)
69{
70 *p->addr = p->opcode;
71 flush_icache_range((unsigned long)p->addr,
72 (unsigned long)p->addr + sizeof(kprobe_opcode_t));
73}
74
75int __kprobes arch_trampoline_kprobe(struct kprobe *p)
76{
77 if (*p->addr == BREAKPOINT_INSTRUCTION)
78 return 1;
79
80 return 0;
81}
82
83/**
84 * If an illegal slot instruction exception occurs for an address
85 * containing a kprobe, remove the probe.
86 *
87 * Returns 0 if the exception was handled successfully, 1 otherwise.
88 */
89int __kprobes kprobe_handle_illslot(unsigned long pc)
90{
91 struct kprobe *p = get_kprobe((kprobe_opcode_t *) pc + 1);
92
93 if (p != NULL) {
94 printk("Warning: removing kprobe from delay slot: 0x%.8x\n",
95 (unsigned int)pc + 2);
96 unregister_kprobe(p);
97 return 0;
98 }
99
100 return 1;
101}
102
103void __kprobes arch_remove_kprobe(struct kprobe *p)
104{
105 struct kprobe *saved = &__get_cpu_var(saved_next_opcode);
106
107 if (saved->addr) {
108 arch_disarm_kprobe(p);
109 arch_disarm_kprobe(saved);
110
111 saved->addr = NULL;
112 saved->opcode = 0;
113
114 saved = &__get_cpu_var(saved_next_opcode2);
115 if (saved->addr) {
116 arch_disarm_kprobe(saved);
117
118 saved->addr = NULL;
119 saved->opcode = 0;
120 }
121 }
122}
123
124static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
125{
126 kcb->prev_kprobe.kp = kprobe_running();
127 kcb->prev_kprobe.status = kcb->kprobe_status;
128}
129
130static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
131{
132 __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
133 kcb->kprobe_status = kcb->prev_kprobe.status;
134}
135
136static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
137 struct kprobe_ctlblk *kcb)
138{
139 __get_cpu_var(current_kprobe) = p;
140}
141
142/*
143 * Singlestep is implemented by disabling the current kprobe and setting one
144 * on the next instruction, following branches. Two probes are set if the
145 * branch is conditional.
146 */
147static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
148{
149 __get_cpu_var(saved_current_opcode).addr = (kprobe_opcode_t *)regs->pc;
150
151 if (p != NULL) {
152 struct kprobe *op1, *op2;
153
154 arch_disarm_kprobe(p);
155
156 op1 = &__get_cpu_var(saved_next_opcode);
157 op2 = &__get_cpu_var(saved_next_opcode2);
158
159 if (OPCODE_JSR(p->opcode) || OPCODE_JMP(p->opcode)) {
160 unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
161 op1->addr = (kprobe_opcode_t *) regs->regs[reg_nr];
162 } else if (OPCODE_BRA(p->opcode) || OPCODE_BSR(p->opcode)) {
163 unsigned long disp = (p->opcode & 0x0FFF);
164 op1->addr =
165 (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
166
167 } else if (OPCODE_BRAF(p->opcode) || OPCODE_BSRF(p->opcode)) {
168 unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
169 op1->addr =
170 (kprobe_opcode_t *) (regs->pc + 4 +
171 regs->regs[reg_nr]);
172
173 } else if (OPCODE_RTS(p->opcode)) {
174 op1->addr = (kprobe_opcode_t *) regs->pr;
175
176 } else if (OPCODE_BF(p->opcode) || OPCODE_BT(p->opcode)) {
177 unsigned long disp = (p->opcode & 0x00FF);
178 /* case 1 */
179 op1->addr = p->addr + 1;
180 /* case 2 */
181 op2->addr =
182 (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
183 op2->opcode = *(op2->addr);
184 arch_arm_kprobe(op2);
185
186 } else if (OPCODE_BF_S(p->opcode) || OPCODE_BT_S(p->opcode)) {
187 unsigned long disp = (p->opcode & 0x00FF);
188 /* case 1 */
189 op1->addr = p->addr + 2;
190 /* case 2 */
191 op2->addr =
192 (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
193 op2->opcode = *(op2->addr);
194 arch_arm_kprobe(op2);
195
196 } else {
197 op1->addr = p->addr + 1;
198 }
199
200 op1->opcode = *(op1->addr);
201 arch_arm_kprobe(op1);
202 }
203}
204
205/* Called with kretprobe_lock held */
206void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
207 struct pt_regs *regs)
208{
209 ri->ret_addr = (kprobe_opcode_t *) regs->pr;
210
211 /* Replace the return addr with trampoline addr */
212 regs->pr = (unsigned long)kretprobe_trampoline;
213}
214
215static int __kprobes kprobe_handler(struct pt_regs *regs)
216{
217 struct kprobe *p;
218 int ret = 0;
219 kprobe_opcode_t *addr = NULL;
220 struct kprobe_ctlblk *kcb;
221
222 /*
223 * We don't want to be preempted for the entire
224 * duration of kprobe processing
225 */
226 preempt_disable();
227 kcb = get_kprobe_ctlblk();
228
229 addr = (kprobe_opcode_t *) (regs->pc);
230
231 /* Check we're not actually recursing */
232 if (kprobe_running()) {
233 p = get_kprobe(addr);
234 if (p) {
235 if (kcb->kprobe_status == KPROBE_HIT_SS &&
236 *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
237 goto no_kprobe;
238 }
239 /* We have reentered the kprobe_handler(), since
240 * another probe was hit while within the handler.
241 * We here save the original kprobes variables and
242 * just single step on the instruction of the new probe
243 * without calling any user handlers.
244 */
245 save_previous_kprobe(kcb);
246 set_current_kprobe(p, regs, kcb);
247 kprobes_inc_nmissed_count(p);
248 prepare_singlestep(p, regs);
249 kcb->kprobe_status = KPROBE_REENTER;
250 return 1;
251 } else {
252 p = __get_cpu_var(current_kprobe);
253 if (p->break_handler && p->break_handler(p, regs)) {
254 goto ss_probe;
255 }
256 }
257 goto no_kprobe;
258 }
259
260 p = get_kprobe(addr);
261 if (!p) {
262 /* Not one of ours: let kernel handle it */
263 if (*(kprobe_opcode_t *)addr != BREAKPOINT_INSTRUCTION) {
264 /*
265 * The breakpoint instruction was removed right
266 * after we hit it. Another cpu has removed
267 * either a probepoint or a debugger breakpoint
268 * at this address. In either case, no further
269 * handling of this interrupt is appropriate.
270 */
271 ret = 1;
272 }
273
274 goto no_kprobe;
275 }
276
277 set_current_kprobe(p, regs, kcb);
278 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
279
280 if (p->pre_handler && p->pre_handler(p, regs))
281 /* handler has already set things up, so skip ss setup */
282 return 1;
283
284ss_probe:
285 prepare_singlestep(p, regs);
286 kcb->kprobe_status = KPROBE_HIT_SS;
287 return 1;
288
289no_kprobe:
290 preempt_enable_no_resched();
291 return ret;
292}
293
294/*
295 * For function-return probes, init_kprobes() establishes a probepoint
296 * here. When a retprobed function returns, this probe is hit and
297 * trampoline_probe_handler() runs, calling the kretprobe's handler.
298 */
299static void __used kretprobe_trampoline_holder(void)
300{
301 asm volatile (".globl kretprobe_trampoline\n"
302 "kretprobe_trampoline:\n\t"
303 "nop\n");
304}
305
306/*
307 * Called when we hit the probe point at kretprobe_trampoline
308 */
309int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
310{
311 struct kretprobe_instance *ri = NULL;
312 struct hlist_head *head, empty_rp;
313 struct hlist_node *tmp;
314 unsigned long flags, orig_ret_address = 0;
315 unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
316
317 INIT_HLIST_HEAD(&empty_rp);
318 kretprobe_hash_lock(current, &head, &flags);
319
320 /*
321 * It is possible to have multiple instances associated with a given
322 * task either because an multiple functions in the call path
323 * have a return probe installed on them, and/or more then one return
324 * return probe was registered for a target function.
325 *
326 * We can handle this because:
327 * - instances are always inserted at the head of the list
328 * - when multiple return probes are registered for the same
329 * function, the first instance's ret_addr will point to the
330 * real return address, and all the rest will point to
331 * kretprobe_trampoline
332 */
333 hlist_for_each_entry_safe(ri, tmp, head, hlist) {
334 if (ri->task != current)
335 /* another task is sharing our hash bucket */
336 continue;
337
338 if (ri->rp && ri->rp->handler) {
339 __get_cpu_var(current_kprobe) = &ri->rp->kp;
340 ri->rp->handler(ri, regs);
341 __get_cpu_var(current_kprobe) = NULL;
342 }
343
344 orig_ret_address = (unsigned long)ri->ret_addr;
345 recycle_rp_inst(ri, &empty_rp);
346
347 if (orig_ret_address != trampoline_address)
348 /*
349 * This is the real return address. Any other
350 * instances associated with this task are for
351 * other calls deeper on the call stack
352 */
353 break;
354 }
355
356 kretprobe_assert(ri, orig_ret_address, trampoline_address);
357
358 regs->pc = orig_ret_address;
359 kretprobe_hash_unlock(current, &flags);
360
361 preempt_enable_no_resched();
362
363 hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
364 hlist_del(&ri->hlist);
365 kfree(ri);
366 }
367
368 return orig_ret_address;
369}
370
371static int __kprobes post_kprobe_handler(struct pt_regs *regs)
372{
373 struct kprobe *cur = kprobe_running();
374 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
375 kprobe_opcode_t *addr = NULL;
376 struct kprobe *p = NULL;
377
378 if (!cur)
379 return 0;
380
381 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
382 kcb->kprobe_status = KPROBE_HIT_SSDONE;
383 cur->post_handler(cur, regs, 0);
384 }
385
386 p = &__get_cpu_var(saved_next_opcode);
387 if (p->addr) {
388 arch_disarm_kprobe(p);
389 p->addr = NULL;
390 p->opcode = 0;
391
392 addr = __get_cpu_var(saved_current_opcode).addr;
393 __get_cpu_var(saved_current_opcode).addr = NULL;
394
395 p = get_kprobe(addr);
396 arch_arm_kprobe(p);
397
398 p = &__get_cpu_var(saved_next_opcode2);
399 if (p->addr) {
400 arch_disarm_kprobe(p);
401 p->addr = NULL;
402 p->opcode = 0;
403 }
404 }
405
406 /* Restore back the original saved kprobes variables and continue. */
407 if (kcb->kprobe_status == KPROBE_REENTER) {
408 restore_previous_kprobe(kcb);
409 goto out;
410 }
411
412 reset_current_kprobe();
413
414out:
415 preempt_enable_no_resched();
416
417 return 1;
418}
419
420int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
421{
422 struct kprobe *cur = kprobe_running();
423 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
424 const struct exception_table_entry *entry;
425
426 switch (kcb->kprobe_status) {
427 case KPROBE_HIT_SS:
428 case KPROBE_REENTER:
429 /*
430 * We are here because the instruction being single
431 * stepped caused a page fault. We reset the current
432 * kprobe, point the pc back to the probe address
433 * and allow the page fault handler to continue as a
434 * normal page fault.
435 */
436 regs->pc = (unsigned long)cur->addr;
437 if (kcb->kprobe_status == KPROBE_REENTER)
438 restore_previous_kprobe(kcb);
439 else
440 reset_current_kprobe();
441 preempt_enable_no_resched();
442 break;
443 case KPROBE_HIT_ACTIVE:
444 case KPROBE_HIT_SSDONE:
445 /*
446 * We increment the nmissed count for accounting,
447 * we can also use npre/npostfault count for accounting
448 * these specific fault cases.
449 */
450 kprobes_inc_nmissed_count(cur);
451
452 /*
453 * We come here because instructions in the pre/post
454 * handler caused the page_fault, this could happen
455 * if handler tries to access user space by
456 * copy_from_user(), get_user() etc. Let the
457 * user-specified handler try to fix it first.
458 */
459 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
460 return 1;
461
462 /*
463 * In case the user-specified fault handler returned
464 * zero, try to fix up.
465 */
466 if ((entry = search_exception_tables(regs->pc)) != NULL) {
467 regs->pc = entry->fixup;
468 return 1;
469 }
470
471 /*
472 * fixup_exception() could not handle it,
473 * Let do_page_fault() fix it.
474 */
475 break;
476 default:
477 break;
478 }
479
480 return 0;
481}
482
483/*
484 * Wrapper routine to for handling exceptions.
485 */
486int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
487 unsigned long val, void *data)
488{
489 struct kprobe *p = NULL;
490 struct die_args *args = (struct die_args *)data;
491 int ret = NOTIFY_DONE;
492 kprobe_opcode_t *addr = NULL;
493 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
494
495 addr = (kprobe_opcode_t *) (args->regs->pc);
496 if (val == DIE_TRAP) {
497 if (!kprobe_running()) {
498 if (kprobe_handler(args->regs)) {
499 ret = NOTIFY_STOP;
500 } else {
501 /* Not a kprobe trap */
502 ret = NOTIFY_DONE;
503 }
504 } else {
505 p = get_kprobe(addr);
506 if ((kcb->kprobe_status == KPROBE_HIT_SS) ||
507 (kcb->kprobe_status == KPROBE_REENTER)) {
508 if (post_kprobe_handler(args->regs))
509 ret = NOTIFY_STOP;
510 } else {
511 if (kprobe_handler(args->regs)) {
512 ret = NOTIFY_STOP;
513 } else {
514 p = __get_cpu_var(current_kprobe);
515 if (p->break_handler &&
516 p->break_handler(p, args->regs))
517 ret = NOTIFY_STOP;
518 }
519 }
520 }
521 }
522
523 return ret;
524}
525
526int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
527{
528 struct jprobe *jp = container_of(p, struct jprobe, kp);
529 unsigned long addr;
530 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
531
532 kcb->jprobe_saved_regs = *regs;
533 kcb->jprobe_saved_r15 = regs->regs[15];
534 addr = kcb->jprobe_saved_r15;
535
536 /*
537 * TBD: As Linus pointed out, gcc assumes that the callee
538 * owns the argument space and could overwrite it, e.g.
539 * tailcall optimization. So, to be absolutely safe
540 * we also save and restore enough stack bytes to cover
541 * the argument area.
542 */
543 memcpy(kcb->jprobes_stack, (kprobe_opcode_t *) addr,
544 MIN_STACK_SIZE(addr));
545
546 regs->pc = (unsigned long)(jp->entry);
547
548 return 1;
549}
550
551void __kprobes jprobe_return(void)
552{
553 asm volatile ("trapa #0x3a\n\t" "jprobe_return_end:\n\t" "nop\n\t");
554}
555
556int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
557{
558 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
559 unsigned long stack_addr = kcb->jprobe_saved_r15;
560 u8 *addr = (u8 *)regs->pc;
561
562 if ((addr >= (u8 *)jprobe_return) &&
563 (addr <= (u8 *)jprobe_return_end)) {
564 *regs = kcb->jprobe_saved_regs;
565
566 memcpy((kprobe_opcode_t *)stack_addr, kcb->jprobes_stack,
567 MIN_STACK_SIZE(stack_addr));
568
569 kcb->kprobe_status = KPROBE_HIT_SS;
570 preempt_enable_no_resched();
571 return 1;
572 }
573
574 return 0;
575}
576
577static struct kprobe trampoline_p = {
578 .addr = (kprobe_opcode_t *)&kretprobe_trampoline,
579 .pre_handler = trampoline_probe_handler
580};
581
582int __init arch_init_kprobes(void)
583{
584 return register_kprobe(&trampoline_p);
585}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Kernel probes (kprobes) for SuperH
4 *
5 * Copyright (C) 2007 Chris Smith <chris.smith@st.com>
6 * Copyright (C) 2006 Lineo Solutions, Inc.
7 */
8#include <linux/kprobes.h>
9#include <linux/extable.h>
10#include <linux/ptrace.h>
11#include <linux/preempt.h>
12#include <linux/kdebug.h>
13#include <linux/slab.h>
14#include <asm/cacheflush.h>
15#include <linux/uaccess.h>
16
17DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
18DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
19
20static DEFINE_PER_CPU(struct kprobe, saved_current_opcode);
21static DEFINE_PER_CPU(struct kprobe, saved_next_opcode);
22static DEFINE_PER_CPU(struct kprobe, saved_next_opcode2);
23
24#define OPCODE_JMP(x) (((x) & 0xF0FF) == 0x402b)
25#define OPCODE_JSR(x) (((x) & 0xF0FF) == 0x400b)
26#define OPCODE_BRA(x) (((x) & 0xF000) == 0xa000)
27#define OPCODE_BRAF(x) (((x) & 0xF0FF) == 0x0023)
28#define OPCODE_BSR(x) (((x) & 0xF000) == 0xb000)
29#define OPCODE_BSRF(x) (((x) & 0xF0FF) == 0x0003)
30
31#define OPCODE_BF_S(x) (((x) & 0xFF00) == 0x8f00)
32#define OPCODE_BT_S(x) (((x) & 0xFF00) == 0x8d00)
33
34#define OPCODE_BF(x) (((x) & 0xFF00) == 0x8b00)
35#define OPCODE_BT(x) (((x) & 0xFF00) == 0x8900)
36
37#define OPCODE_RTS(x) (((x) & 0x000F) == 0x000b)
38#define OPCODE_RTE(x) (((x) & 0xFFFF) == 0x002b)
39
40int __kprobes arch_prepare_kprobe(struct kprobe *p)
41{
42 kprobe_opcode_t opcode = *p->addr;
43
44 if (OPCODE_RTE(opcode))
45 return -EFAULT; /* Bad breakpoint */
46
47 memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
48 p->opcode = opcode;
49
50 return 0;
51}
52
53void __kprobes arch_arm_kprobe(struct kprobe *p)
54{
55 *p->addr = BREAKPOINT_INSTRUCTION;
56 flush_icache_range((unsigned long)p->addr,
57 (unsigned long)p->addr + sizeof(kprobe_opcode_t));
58}
59
60void __kprobes arch_disarm_kprobe(struct kprobe *p)
61{
62 *p->addr = p->opcode;
63 flush_icache_range((unsigned long)p->addr,
64 (unsigned long)p->addr + sizeof(kprobe_opcode_t));
65}
66
67int __kprobes arch_trampoline_kprobe(struct kprobe *p)
68{
69 if (*p->addr == BREAKPOINT_INSTRUCTION)
70 return 1;
71
72 return 0;
73}
74
75/**
76 * If an illegal slot instruction exception occurs for an address
77 * containing a kprobe, remove the probe.
78 *
79 * Returns 0 if the exception was handled successfully, 1 otherwise.
80 */
81int __kprobes kprobe_handle_illslot(unsigned long pc)
82{
83 struct kprobe *p = get_kprobe((kprobe_opcode_t *) pc + 1);
84
85 if (p != NULL) {
86 printk("Warning: removing kprobe from delay slot: 0x%.8x\n",
87 (unsigned int)pc + 2);
88 unregister_kprobe(p);
89 return 0;
90 }
91
92 return 1;
93}
94
95void __kprobes arch_remove_kprobe(struct kprobe *p)
96{
97 struct kprobe *saved = this_cpu_ptr(&saved_next_opcode);
98
99 if (saved->addr) {
100 arch_disarm_kprobe(p);
101 arch_disarm_kprobe(saved);
102
103 saved->addr = NULL;
104 saved->opcode = 0;
105
106 saved = this_cpu_ptr(&saved_next_opcode2);
107 if (saved->addr) {
108 arch_disarm_kprobe(saved);
109
110 saved->addr = NULL;
111 saved->opcode = 0;
112 }
113 }
114}
115
116static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
117{
118 kcb->prev_kprobe.kp = kprobe_running();
119 kcb->prev_kprobe.status = kcb->kprobe_status;
120}
121
122static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
123{
124 __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
125 kcb->kprobe_status = kcb->prev_kprobe.status;
126}
127
128static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
129 struct kprobe_ctlblk *kcb)
130{
131 __this_cpu_write(current_kprobe, p);
132}
133
134/*
135 * Singlestep is implemented by disabling the current kprobe and setting one
136 * on the next instruction, following branches. Two probes are set if the
137 * branch is conditional.
138 */
139static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
140{
141 __this_cpu_write(saved_current_opcode.addr, (kprobe_opcode_t *)regs->pc);
142
143 if (p != NULL) {
144 struct kprobe *op1, *op2;
145
146 arch_disarm_kprobe(p);
147
148 op1 = this_cpu_ptr(&saved_next_opcode);
149 op2 = this_cpu_ptr(&saved_next_opcode2);
150
151 if (OPCODE_JSR(p->opcode) || OPCODE_JMP(p->opcode)) {
152 unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
153 op1->addr = (kprobe_opcode_t *) regs->regs[reg_nr];
154 } else if (OPCODE_BRA(p->opcode) || OPCODE_BSR(p->opcode)) {
155 unsigned long disp = (p->opcode & 0x0FFF);
156 op1->addr =
157 (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
158
159 } else if (OPCODE_BRAF(p->opcode) || OPCODE_BSRF(p->opcode)) {
160 unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
161 op1->addr =
162 (kprobe_opcode_t *) (regs->pc + 4 +
163 regs->regs[reg_nr]);
164
165 } else if (OPCODE_RTS(p->opcode)) {
166 op1->addr = (kprobe_opcode_t *) regs->pr;
167
168 } else if (OPCODE_BF(p->opcode) || OPCODE_BT(p->opcode)) {
169 unsigned long disp = (p->opcode & 0x00FF);
170 /* case 1 */
171 op1->addr = p->addr + 1;
172 /* case 2 */
173 op2->addr =
174 (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
175 op2->opcode = *(op2->addr);
176 arch_arm_kprobe(op2);
177
178 } else if (OPCODE_BF_S(p->opcode) || OPCODE_BT_S(p->opcode)) {
179 unsigned long disp = (p->opcode & 0x00FF);
180 /* case 1 */
181 op1->addr = p->addr + 2;
182 /* case 2 */
183 op2->addr =
184 (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
185 op2->opcode = *(op2->addr);
186 arch_arm_kprobe(op2);
187
188 } else {
189 op1->addr = p->addr + 1;
190 }
191
192 op1->opcode = *(op1->addr);
193 arch_arm_kprobe(op1);
194 }
195}
196
197/* Called with kretprobe_lock held */
198void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
199 struct pt_regs *regs)
200{
201 ri->ret_addr = (kprobe_opcode_t *) regs->pr;
202 ri->fp = NULL;
203
204 /* Replace the return addr with trampoline addr */
205 regs->pr = (unsigned long)__kretprobe_trampoline;
206}
207
208static int __kprobes kprobe_handler(struct pt_regs *regs)
209{
210 struct kprobe *p;
211 int ret = 0;
212 kprobe_opcode_t *addr = NULL;
213 struct kprobe_ctlblk *kcb;
214
215 /*
216 * We don't want to be preempted for the entire
217 * duration of kprobe processing
218 */
219 preempt_disable();
220 kcb = get_kprobe_ctlblk();
221
222 addr = (kprobe_opcode_t *) (regs->pc);
223
224 /* Check we're not actually recursing */
225 if (kprobe_running()) {
226 p = get_kprobe(addr);
227 if (p) {
228 if (kcb->kprobe_status == KPROBE_HIT_SS &&
229 *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
230 goto no_kprobe;
231 }
232 /* We have reentered the kprobe_handler(), since
233 * another probe was hit while within the handler.
234 * We here save the original kprobes variables and
235 * just single step on the instruction of the new probe
236 * without calling any user handlers.
237 */
238 save_previous_kprobe(kcb);
239 set_current_kprobe(p, regs, kcb);
240 kprobes_inc_nmissed_count(p);
241 prepare_singlestep(p, regs);
242 kcb->kprobe_status = KPROBE_REENTER;
243 return 1;
244 }
245 goto no_kprobe;
246 }
247
248 p = get_kprobe(addr);
249 if (!p) {
250 /* Not one of ours: let kernel handle it */
251 if (*addr != BREAKPOINT_INSTRUCTION) {
252 /*
253 * The breakpoint instruction was removed right
254 * after we hit it. Another cpu has removed
255 * either a probepoint or a debugger breakpoint
256 * at this address. In either case, no further
257 * handling of this interrupt is appropriate.
258 */
259 ret = 1;
260 }
261
262 goto no_kprobe;
263 }
264
265 set_current_kprobe(p, regs, kcb);
266 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
267
268 if (p->pre_handler && p->pre_handler(p, regs)) {
269 /* handler has already set things up, so skip ss setup */
270 reset_current_kprobe();
271 preempt_enable_no_resched();
272 return 1;
273 }
274
275 prepare_singlestep(p, regs);
276 kcb->kprobe_status = KPROBE_HIT_SS;
277 return 1;
278
279no_kprobe:
280 preempt_enable_no_resched();
281 return ret;
282}
283
284/*
285 * For function-return probes, init_kprobes() establishes a probepoint
286 * here. When a retprobed function returns, this probe is hit and
287 * trampoline_probe_handler() runs, calling the kretprobe's handler.
288 */
289static void __used kretprobe_trampoline_holder(void)
290{
291 asm volatile (".globl __kretprobe_trampoline\n"
292 "__kretprobe_trampoline:\n\t"
293 "nop\n");
294}
295
296/*
297 * Called when we hit the probe point at __kretprobe_trampoline
298 */
299static int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
300{
301 regs->pc = __kretprobe_trampoline_handler(regs, NULL);
302
303 return 1;
304}
305
306static int __kprobes post_kprobe_handler(struct pt_regs *regs)
307{
308 struct kprobe *cur = kprobe_running();
309 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
310 kprobe_opcode_t *addr = NULL;
311 struct kprobe *p = NULL;
312
313 if (!cur)
314 return 0;
315
316 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
317 kcb->kprobe_status = KPROBE_HIT_SSDONE;
318 cur->post_handler(cur, regs, 0);
319 }
320
321 p = this_cpu_ptr(&saved_next_opcode);
322 if (p->addr) {
323 arch_disarm_kprobe(p);
324 p->addr = NULL;
325 p->opcode = 0;
326
327 addr = __this_cpu_read(saved_current_opcode.addr);
328 __this_cpu_write(saved_current_opcode.addr, NULL);
329
330 p = get_kprobe(addr);
331 arch_arm_kprobe(p);
332
333 p = this_cpu_ptr(&saved_next_opcode2);
334 if (p->addr) {
335 arch_disarm_kprobe(p);
336 p->addr = NULL;
337 p->opcode = 0;
338 }
339 }
340
341 /* Restore back the original saved kprobes variables and continue. */
342 if (kcb->kprobe_status == KPROBE_REENTER) {
343 restore_previous_kprobe(kcb);
344 goto out;
345 }
346
347 reset_current_kprobe();
348
349out:
350 preempt_enable_no_resched();
351
352 return 1;
353}
354
355int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
356{
357 struct kprobe *cur = kprobe_running();
358 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
359 const struct exception_table_entry *entry;
360
361 switch (kcb->kprobe_status) {
362 case KPROBE_HIT_SS:
363 case KPROBE_REENTER:
364 /*
365 * We are here because the instruction being single
366 * stepped caused a page fault. We reset the current
367 * kprobe, point the pc back to the probe address
368 * and allow the page fault handler to continue as a
369 * normal page fault.
370 */
371 regs->pc = (unsigned long)cur->addr;
372 if (kcb->kprobe_status == KPROBE_REENTER)
373 restore_previous_kprobe(kcb);
374 else
375 reset_current_kprobe();
376 preempt_enable_no_resched();
377 break;
378 case KPROBE_HIT_ACTIVE:
379 case KPROBE_HIT_SSDONE:
380 /*
381 * In case the user-specified fault handler returned
382 * zero, try to fix up.
383 */
384 if ((entry = search_exception_tables(regs->pc)) != NULL) {
385 regs->pc = entry->fixup;
386 return 1;
387 }
388
389 /*
390 * fixup_exception() could not handle it,
391 * Let do_page_fault() fix it.
392 */
393 break;
394 default:
395 break;
396 }
397
398 return 0;
399}
400
401/*
402 * Wrapper routine to for handling exceptions.
403 */
404int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
405 unsigned long val, void *data)
406{
407 struct kprobe *p = NULL;
408 struct die_args *args = (struct die_args *)data;
409 int ret = NOTIFY_DONE;
410 kprobe_opcode_t *addr = NULL;
411 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
412
413 addr = (kprobe_opcode_t *) (args->regs->pc);
414 if (val == DIE_TRAP &&
415 args->trapnr == (BREAKPOINT_INSTRUCTION & 0xff)) {
416 if (!kprobe_running()) {
417 if (kprobe_handler(args->regs)) {
418 ret = NOTIFY_STOP;
419 } else {
420 /* Not a kprobe trap */
421 ret = NOTIFY_DONE;
422 }
423 } else {
424 p = get_kprobe(addr);
425 if ((kcb->kprobe_status == KPROBE_HIT_SS) ||
426 (kcb->kprobe_status == KPROBE_REENTER)) {
427 if (post_kprobe_handler(args->regs))
428 ret = NOTIFY_STOP;
429 } else {
430 if (kprobe_handler(args->regs))
431 ret = NOTIFY_STOP;
432 }
433 }
434 }
435
436 return ret;
437}
438
439static struct kprobe trampoline_p = {
440 .addr = (kprobe_opcode_t *)&__kretprobe_trampoline,
441 .pre_handler = trampoline_probe_handler
442};
443
444int __init arch_init_kprobes(void)
445{
446 return register_kprobe(&trampoline_p);
447}