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-rw-r--r--arch/sh/kernel/kprobes.c584
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diff --git a/arch/sh/kernel/kprobes.c b/arch/sh/kernel/kprobes.c
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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 <asm/cacheflush.h>
17#include <asm/uaccess.h>
18
19DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
20DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
21
22static struct kprobe saved_current_opcode;
23static struct kprobe saved_next_opcode;
24static struct kprobe saved_next_opcode2;
25
26#define OPCODE_JMP(x) (((x) & 0xF0FF) == 0x402b)
27#define OPCODE_JSR(x) (((x) & 0xF0FF) == 0x400b)
28#define OPCODE_BRA(x) (((x) & 0xF000) == 0xa000)
29#define OPCODE_BRAF(x) (((x) & 0xF0FF) == 0x0023)
30#define OPCODE_BSR(x) (((x) & 0xF000) == 0xb000)
31#define OPCODE_BSRF(x) (((x) & 0xF0FF) == 0x0003)
32
33#define OPCODE_BF_S(x) (((x) & 0xFF00) == 0x8f00)
34#define OPCODE_BT_S(x) (((x) & 0xFF00) == 0x8d00)
35
36#define OPCODE_BF(x) (((x) & 0xFF00) == 0x8b00)
37#define OPCODE_BT(x) (((x) & 0xFF00) == 0x8900)
38
39#define OPCODE_RTS(x) (((x) & 0x000F) == 0x000b)
40#define OPCODE_RTE(x) (((x) & 0xFFFF) == 0x002b)
41
42int __kprobes arch_prepare_kprobe(struct kprobe *p)
43{
44 kprobe_opcode_t opcode = *(kprobe_opcode_t *) (p->addr);
45
46 if (OPCODE_RTE(opcode))
47 return -EFAULT; /* Bad breakpoint */
48
49 p->opcode = opcode;
50
51 return 0;
52}
53
54void __kprobes arch_copy_kprobe(struct kprobe *p)
55{
56 memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
57 p->opcode = *p->addr;
58}
59
60void __kprobes arch_arm_kprobe(struct kprobe *p)
61{
62 *p->addr = BREAKPOINT_INSTRUCTION;
63 flush_icache_range((unsigned long)p->addr,
64 (unsigned long)p->addr + sizeof(kprobe_opcode_t));
65}
66
67void __kprobes arch_disarm_kprobe(struct kprobe *p)
68{
69 *p->addr = p->opcode;
70 flush_icache_range((unsigned long)p->addr,
71 (unsigned long)p->addr + sizeof(kprobe_opcode_t));
72}
73
74int __kprobes arch_trampoline_kprobe(struct kprobe *p)
75{
76 if (*p->addr == BREAKPOINT_INSTRUCTION)
77 return 1;
78
79 return 0;
80}
81
82/**
83 * If an illegal slot instruction exception occurs for an address
84 * containing a kprobe, remove the probe.
85 *
86 * Returns 0 if the exception was handled successfully, 1 otherwise.
87 */
88int __kprobes kprobe_handle_illslot(unsigned long pc)
89{
90 struct kprobe *p = get_kprobe((kprobe_opcode_t *) pc + 1);
91
92 if (p != NULL) {
93 printk("Warning: removing kprobe from delay slot: 0x%.8x\n",
94 (unsigned int)pc + 2);
95 unregister_kprobe(p);
96 return 0;
97 }
98
99 return 1;
100}
101
102void __kprobes arch_remove_kprobe(struct kprobe *p)
103{
104 if (saved_next_opcode.addr != 0x0) {
105 arch_disarm_kprobe(p);
106 arch_disarm_kprobe(&saved_next_opcode);
107 saved_next_opcode.addr = 0x0;
108 saved_next_opcode.opcode = 0x0;
109
110 if (saved_next_opcode2.addr != 0x0) {
111 arch_disarm_kprobe(&saved_next_opcode2);
112 saved_next_opcode2.addr = 0x0;
113 saved_next_opcode2.opcode = 0x0;
114 }
115 }
116}
117
118static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
119{
120 kcb->prev_kprobe.kp = kprobe_running();
121 kcb->prev_kprobe.status = kcb->kprobe_status;
122}
123
124static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
125{
126 __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
127 kcb->kprobe_status = kcb->prev_kprobe.status;
128}
129
130static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
131 struct kprobe_ctlblk *kcb)
132{
133 __get_cpu_var(current_kprobe) = p;
134}
135
136/*
137 * Singlestep is implemented by disabling the current kprobe and setting one
138 * on the next instruction, following branches. Two probes are set if the
139 * branch is conditional.
140 */
141static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
142{
143 kprobe_opcode_t *addr = NULL;
144 saved_current_opcode.addr = (kprobe_opcode_t *) (regs->pc);
145 addr = saved_current_opcode.addr;
146
147 if (p != NULL) {
148 arch_disarm_kprobe(p);
149
150 if (OPCODE_JSR(p->opcode) || OPCODE_JMP(p->opcode)) {
151 unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
152 saved_next_opcode.addr =
153 (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 saved_next_opcode.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 saved_next_opcode.addr =
162 (kprobe_opcode_t *) (regs->pc + 4 +
163 regs->regs[reg_nr]);
164
165 } else if (OPCODE_RTS(p->opcode)) {
166 saved_next_opcode.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 saved_next_opcode.addr = p->addr + 1;
172 /* case 2 */
173 saved_next_opcode2.addr =
174 (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
175 saved_next_opcode2.opcode = *(saved_next_opcode2.addr);
176 arch_arm_kprobe(&saved_next_opcode2);
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 saved_next_opcode.addr = p->addr + 2;
182 /* case 2 */
183 saved_next_opcode2.addr =
184 (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
185 saved_next_opcode2.opcode = *(saved_next_opcode2.addr);
186 arch_arm_kprobe(&saved_next_opcode2);
187
188 } else {
189 saved_next_opcode.addr = p->addr + 1;
190 }
191
192 saved_next_opcode.opcode = *(saved_next_opcode.addr);
193 arch_arm_kprobe(&saved_next_opcode);
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
203 /* Replace the return addr with trampoline addr */
204 regs->pr = (unsigned long)kretprobe_trampoline;
205}
206
207static int __kprobes kprobe_handler(struct pt_regs *regs)
208{
209 struct kprobe *p;
210 int ret = 0;
211 kprobe_opcode_t *addr = NULL;
212 struct kprobe_ctlblk *kcb;
213
214 /*
215 * We don't want to be preempted for the entire
216 * duration of kprobe processing
217 */
218 preempt_disable();
219 kcb = get_kprobe_ctlblk();
220
221 addr = (kprobe_opcode_t *) (regs->pc);
222
223 /* Check we're not actually recursing */
224 if (kprobe_running()) {
225 p = get_kprobe(addr);
226 if (p) {
227 if (kcb->kprobe_status == KPROBE_HIT_SS &&
228 *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
229 goto no_kprobe;
230 }
231 /* We have reentered the kprobe_handler(), since
232 * another probe was hit while within the handler.
233 * We here save the original kprobes variables and
234 * just single step on the instruction of the new probe
235 * without calling any user handlers.
236 */
237 save_previous_kprobe(kcb);
238 set_current_kprobe(p, regs, kcb);
239 kprobes_inc_nmissed_count(p);
240 prepare_singlestep(p, regs);
241 kcb->kprobe_status = KPROBE_REENTER;
242 return 1;
243 } else {
244 p = __get_cpu_var(current_kprobe);
245 if (p->break_handler && p->break_handler(p, regs)) {
246 goto ss_probe;
247 }
248 }
249 goto no_kprobe;
250 }
251
252 p = get_kprobe(addr);
253 if (!p) {
254 /* Not one of ours: let kernel handle it */
255 if (*(kprobe_opcode_t *)addr != BREAKPOINT_INSTRUCTION) {
256 /*
257 * The breakpoint instruction was removed right
258 * after we hit it. Another cpu has removed
259 * either a probepoint or a debugger breakpoint
260 * at this address. In either case, no further
261 * handling of this interrupt is appropriate.
262 */
263 ret = 1;
264 }
265
266 goto no_kprobe;
267 }
268
269 set_current_kprobe(p, regs, kcb);
270 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
271
272 if (p->pre_handler && p->pre_handler(p, regs))
273 /* handler has already set things up, so skip ss setup */
274 return 1;
275
276ss_probe:
277 prepare_singlestep(p, regs);
278 kcb->kprobe_status = KPROBE_HIT_SS;
279 return 1;
280
281no_kprobe:
282 preempt_enable_no_resched();
283 return ret;
284}
285
286/*
287 * For function-return probes, init_kprobes() establishes a probepoint
288 * here. When a retprobed function returns, this probe is hit and
289 * trampoline_probe_handler() runs, calling the kretprobe's handler.
290 */
291static void __used kretprobe_trampoline_holder(void)
292{
293 asm volatile (".globl kretprobe_trampoline\n"
294 "kretprobe_trampoline:\n\t"
295 "nop\n");
296}
297
298/*
299 * Called when we hit the probe point at kretprobe_trampoline
300 */
301int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
302{
303 struct kretprobe_instance *ri = NULL;
304 struct hlist_head *head, empty_rp;
305 struct hlist_node *node, *tmp;
306 unsigned long flags, orig_ret_address = 0;
307 unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
308
309 INIT_HLIST_HEAD(&empty_rp);
310 kretprobe_hash_lock(current, &head, &flags);
311
312 /*
313 * It is possible to have multiple instances associated with a given
314 * task either because an multiple functions in the call path
315 * have a return probe installed on them, and/or more then one return
316 * return probe was registered for a target function.
317 *
318 * We can handle this because:
319 * - instances are always inserted at the head of the list
320 * - when multiple return probes are registered for the same
321 * function, the first instance's ret_addr will point to the
322 * real return address, and all the rest will point to
323 * kretprobe_trampoline
324 */
325 hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
326 if (ri->task != current)
327 /* another task is sharing our hash bucket */
328 continue;
329
330 if (ri->rp && ri->rp->handler) {
331 __get_cpu_var(current_kprobe) = &ri->rp->kp;
332 ri->rp->handler(ri, regs);
333 __get_cpu_var(current_kprobe) = NULL;
334 }
335
336 orig_ret_address = (unsigned long)ri->ret_addr;
337 recycle_rp_inst(ri, &empty_rp);
338
339 if (orig_ret_address != trampoline_address)
340 /*
341 * This is the real return address. Any other
342 * instances associated with this task are for
343 * other calls deeper on the call stack
344 */
345 break;
346 }
347
348 kretprobe_assert(ri, orig_ret_address, trampoline_address);
349
350 regs->pc = orig_ret_address;
351 kretprobe_hash_unlock(current, &flags);
352
353 preempt_enable_no_resched();
354
355 hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
356 hlist_del(&ri->hlist);
357 kfree(ri);
358 }
359
360 return orig_ret_address;
361}
362
363static int __kprobes post_kprobe_handler(struct pt_regs *regs)
364{
365 struct kprobe *cur = kprobe_running();
366 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
367 kprobe_opcode_t *addr = NULL;
368 struct kprobe *p = NULL;
369
370 if (!cur)
371 return 0;
372
373 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
374 kcb->kprobe_status = KPROBE_HIT_SSDONE;
375 cur->post_handler(cur, regs, 0);
376 }
377
378 if (saved_next_opcode.addr != 0x0) {
379 arch_disarm_kprobe(&saved_next_opcode);
380 saved_next_opcode.addr = 0x0;
381 saved_next_opcode.opcode = 0x0;
382
383 addr = saved_current_opcode.addr;
384 saved_current_opcode.addr = 0x0;
385
386 p = get_kprobe(addr);
387 arch_arm_kprobe(p);
388
389 if (saved_next_opcode2.addr != 0x0) {
390 arch_disarm_kprobe(&saved_next_opcode2);
391 saved_next_opcode2.addr = 0x0;
392 saved_next_opcode2.opcode = 0x0;
393 }
394 }
395
396 /* Restore back the original saved kprobes variables and continue. */
397 if (kcb->kprobe_status == KPROBE_REENTER) {
398 restore_previous_kprobe(kcb);
399 goto out;
400 }
401
402 reset_current_kprobe();
403
404out:
405 preempt_enable_no_resched();
406
407 return 1;
408}
409
410int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
411{
412 struct kprobe *cur = kprobe_running();
413 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
414 const struct exception_table_entry *entry;
415
416 switch (kcb->kprobe_status) {
417 case KPROBE_HIT_SS:
418 case KPROBE_REENTER:
419 /*
420 * We are here because the instruction being single
421 * stepped caused a page fault. We reset the current
422 * kprobe, point the pc back to the probe address
423 * and allow the page fault handler to continue as a
424 * normal page fault.
425 */
426 regs->pc = (unsigned long)cur->addr;
427 if (kcb->kprobe_status == KPROBE_REENTER)
428 restore_previous_kprobe(kcb);
429 else
430 reset_current_kprobe();
431 preempt_enable_no_resched();
432 break;
433 case KPROBE_HIT_ACTIVE:
434 case KPROBE_HIT_SSDONE:
435 /*
436 * We increment the nmissed count for accounting,
437 * we can also use npre/npostfault count for accounting
438 * these specific fault cases.
439 */
440 kprobes_inc_nmissed_count(cur);
441
442 /*
443 * We come here because instructions in the pre/post
444 * handler caused the page_fault, this could happen
445 * if handler tries to access user space by
446 * copy_from_user(), get_user() etc. Let the
447 * user-specified handler try to fix it first.
448 */
449 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
450 return 1;
451
452 /*
453 * In case the user-specified fault handler returned
454 * zero, try to fix up.
455 */
456 if ((entry = search_exception_tables(regs->pc)) != NULL) {
457 regs->pc = entry->fixup;
458 return 1;
459 }
460
461 /*
462 * fixup_exception() could not handle it,
463 * Let do_page_fault() fix it.
464 */
465 break;
466 default:
467 break;
468 }
469
470 return 0;
471}
472
473/*
474 * Wrapper routine to for handling exceptions.
475 */
476int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
477 unsigned long val, void *data)
478{
479 struct kprobe *p = NULL;
480 struct die_args *args = (struct die_args *)data;
481 int ret = NOTIFY_DONE;
482 kprobe_opcode_t *addr = NULL;
483 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
484
485 addr = (kprobe_opcode_t *) (args->regs->pc);
486 if (val == DIE_TRAP) {
487 if (!kprobe_running()) {
488 if (kprobe_handler(args->regs)) {
489 ret = NOTIFY_STOP;
490 } else {
491 /* Not a kprobe trap */
492 ret = NOTIFY_DONE;
493 }
494 } else {
495 p = get_kprobe(addr);
496 if ((kcb->kprobe_status == KPROBE_HIT_SS) ||
497 (kcb->kprobe_status == KPROBE_REENTER)) {
498 if (post_kprobe_handler(args->regs))
499 ret = NOTIFY_STOP;
500 } else {
501 if (kprobe_handler(args->regs)) {
502 ret = NOTIFY_STOP;
503 } else {
504 p = __get_cpu_var(current_kprobe);
505 if (p->break_handler &&
506 p->break_handler(p, args->regs))
507 ret = NOTIFY_STOP;
508 }
509 }
510 }
511 }
512
513 return ret;
514}
515
516int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
517{
518 struct jprobe *jp = container_of(p, struct jprobe, kp);
519 unsigned long addr;
520 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
521
522 kcb->jprobe_saved_regs = *regs;
523 kcb->jprobe_saved_r15 = regs->regs[15];
524 addr = kcb->jprobe_saved_r15;
525
526 /*
527 * TBD: As Linus pointed out, gcc assumes that the callee
528 * owns the argument space and could overwrite it, e.g.
529 * tailcall optimization. So, to be absolutely safe
530 * we also save and restore enough stack bytes to cover
531 * the argument area.
532 */
533 memcpy(kcb->jprobes_stack, (kprobe_opcode_t *) addr,
534 MIN_STACK_SIZE(addr));
535
536 regs->pc = (unsigned long)(jp->entry);
537
538 return 1;
539}
540
541void __kprobes jprobe_return(void)
542{
543 asm volatile ("trapa #0x3a\n\t" "jprobe_return_end:\n\t" "nop\n\t");
544}
545
546int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
547{
548 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
549 unsigned long stack_addr = kcb->jprobe_saved_r15;
550 u8 *addr = (u8 *)regs->pc;
551
552 if ((addr >= (u8 *)jprobe_return) &&
553 (addr <= (u8 *)jprobe_return_end)) {
554 *regs = kcb->jprobe_saved_regs;
555
556 memcpy((kprobe_opcode_t *)stack_addr, kcb->jprobes_stack,
557 MIN_STACK_SIZE(stack_addr));
558
559 kcb->kprobe_status = KPROBE_HIT_SS;
560 preempt_enable_no_resched();
561 return 1;
562 }
563
564 return 0;
565}
566
567static struct kprobe trampoline_p = {
568 .addr = (kprobe_opcode_t *)&kretprobe_trampoline,
569 .pre_handler = trampoline_probe_handler
570};
571
572int __init arch_init_kprobes(void)
573{
574 saved_next_opcode.addr = 0x0;
575 saved_next_opcode.opcode = 0x0;
576
577 saved_current_opcode.addr = 0x0;
578 saved_current_opcode.opcode = 0x0;
579
580 saved_next_opcode2.addr = 0x0;
581 saved_next_opcode2.opcode = 0x0;
582
583 return register_kprobe(&trampoline_p);
584}