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1// SPDX-License-Identifier: GPL-2.0
2/* arch/sparc64/kernel/kprobes.c
3 *
4 * Copyright (C) 2004 David S. Miller <davem@davemloft.net>
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/* We do not have hardware single-stepping on sparc64.
18 * So we implement software single-stepping with breakpoint
19 * traps. The top-level scheme is similar to that used
20 * in the x86 kprobes implementation.
21 *
22 * In the kprobe->ainsn.insn[] array we store the original
23 * instruction at index zero and a break instruction at
24 * index one.
25 *
26 * When we hit a kprobe we:
27 * - Run the pre-handler
28 * - Remember "regs->tnpc" and interrupt level stored in
29 * "regs->tstate" so we can restore them later
30 * - Disable PIL interrupts
31 * - Set regs->tpc to point to kprobe->ainsn.insn[0]
32 * - Set regs->tnpc to point to kprobe->ainsn.insn[1]
33 * - Mark that we are actively in a kprobe
34 *
35 * At this point we wait for the second breakpoint at
36 * kprobe->ainsn.insn[1] to hit. When it does we:
37 * - Run the post-handler
38 * - Set regs->tpc to "remembered" regs->tnpc stored above,
39 * restore the PIL interrupt level in "regs->tstate" as well
40 * - Make any adjustments necessary to regs->tnpc in order
41 * to handle relative branches correctly. See below.
42 * - Mark that we are no longer actively in a kprobe.
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 /*single step inline, if it a breakpoint instruction*/
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 * We don't want to be preempted for the entire
125 * duration of kprobe processing
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 /* We have reentered the kprobe_handler(), since
139 * another probe was hit while within the handler.
140 * We here save the original kprobes variables and
141 * just single step on the instruction of the new probe
142 * without calling any user handlers.
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 {
151 if (*(u32 *)addr != BREAKPOINT_INSTRUCTION) {
152 /* The breakpoint instruction was removed by
153 * another cpu right after we hit, no further
154 * handling of this interrupt is appropriate
155 */
156 ret = 1;
157 goto no_kprobe;
158 }
159 p = __this_cpu_read(current_kprobe);
160 if (p->break_handler && p->break_handler(p, regs))
161 goto ss_probe;
162 }
163 goto no_kprobe;
164 }
165
166 p = get_kprobe(addr);
167 if (!p) {
168 if (*(u32 *)addr != BREAKPOINT_INSTRUCTION) {
169 /*
170 * The breakpoint instruction was removed right
171 * after we hit it. Another cpu has removed
172 * either a probepoint or a debugger breakpoint
173 * at this address. In either case, no further
174 * handling of this interrupt is appropriate.
175 */
176 ret = 1;
177 }
178 /* Not one of ours: let kernel handle it */
179 goto no_kprobe;
180 }
181
182 set_current_kprobe(p, regs, kcb);
183 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
184 if (p->pre_handler && p->pre_handler(p, regs))
185 return 1;
186
187ss_probe:
188 prepare_singlestep(p, regs, kcb);
189 kcb->kprobe_status = KPROBE_HIT_SS;
190 return 1;
191
192no_kprobe:
193 preempt_enable_no_resched();
194 return ret;
195}
196
197/* If INSN is a relative control transfer instruction,
198 * return the corrected branch destination value.
199 *
200 * regs->tpc and regs->tnpc still hold the values of the
201 * program counters at the time of trap due to the execution
202 * of the BREAKPOINT_INSTRUCTION_2 at p->ainsn.insn[1]
203 *
204 */
205static unsigned long __kprobes relbranch_fixup(u32 insn, struct kprobe *p,
206 struct pt_regs *regs)
207{
208 unsigned long real_pc = (unsigned long) p->addr;
209
210 /* Branch not taken, no mods necessary. */
211 if (regs->tnpc == regs->tpc + 0x4UL)
212 return real_pc + 0x8UL;
213
214 /* The three cases are call, branch w/prediction,
215 * and traditional branch.
216 */
217 if ((insn & 0xc0000000) == 0x40000000 ||
218 (insn & 0xc1c00000) == 0x00400000 ||
219 (insn & 0xc1c00000) == 0x00800000) {
220 unsigned long ainsn_addr;
221
222 ainsn_addr = (unsigned long) &p->ainsn.insn[0];
223
224 /* The instruction did all the work for us
225 * already, just apply the offset to the correct
226 * instruction location.
227 */
228 return (real_pc + (regs->tnpc - ainsn_addr));
229 }
230
231 /* It is jmpl or some other absolute PC modification instruction,
232 * leave NPC as-is.
233 */
234 return regs->tnpc;
235}
236
237/* If INSN is an instruction which writes it's PC location
238 * into a destination register, fix that up.
239 */
240static void __kprobes retpc_fixup(struct pt_regs *regs, u32 insn,
241 unsigned long real_pc)
242{
243 unsigned long *slot = NULL;
244
245 /* Simplest case is 'call', which always uses %o7 */
246 if ((insn & 0xc0000000) == 0x40000000) {
247 slot = ®s->u_regs[UREG_I7];
248 }
249
250 /* 'jmpl' encodes the register inside of the opcode */
251 if ((insn & 0xc1f80000) == 0x81c00000) {
252 unsigned long rd = ((insn >> 25) & 0x1f);
253
254 if (rd <= 15) {
255 slot = ®s->u_regs[rd];
256 } else {
257 /* Hard case, it goes onto the stack. */
258 flushw_all();
259
260 rd -= 16;
261 slot = (unsigned long *)
262 (regs->u_regs[UREG_FP] + STACK_BIAS);
263 slot += rd;
264 }
265 }
266 if (slot != NULL)
267 *slot = real_pc;
268}
269
270/*
271 * Called after single-stepping. p->addr is the address of the
272 * instruction which has been replaced by the breakpoint
273 * instruction. To avoid the SMP problems that can occur when we
274 * temporarily put back the original opcode to single-step, we
275 * single-stepped a copy of the instruction. The address of this
276 * copy is &p->ainsn.insn[0].
277 *
278 * This function prepares to return from the post-single-step
279 * breakpoint trap.
280 */
281static void __kprobes resume_execution(struct kprobe *p,
282 struct pt_regs *regs, struct kprobe_ctlblk *kcb)
283{
284 u32 insn = p->ainsn.insn[0];
285
286 regs->tnpc = relbranch_fixup(insn, p, regs);
287
288 /* This assignment must occur after relbranch_fixup() */
289 regs->tpc = kcb->kprobe_orig_tnpc;
290
291 retpc_fixup(regs, insn, (unsigned long) p->addr);
292
293 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
294 kcb->kprobe_orig_tstate_pil);
295}
296
297static int __kprobes post_kprobe_handler(struct pt_regs *regs)
298{
299 struct kprobe *cur = kprobe_running();
300 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
301
302 if (!cur)
303 return 0;
304
305 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
306 kcb->kprobe_status = KPROBE_HIT_SSDONE;
307 cur->post_handler(cur, regs, 0);
308 }
309
310 resume_execution(cur, regs, kcb);
311
312 /*Restore back the original saved kprobes variables and continue. */
313 if (kcb->kprobe_status == KPROBE_REENTER) {
314 restore_previous_kprobe(kcb);
315 goto out;
316 }
317 reset_current_kprobe();
318out:
319 preempt_enable_no_resched();
320
321 return 1;
322}
323
324int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
325{
326 struct kprobe *cur = kprobe_running();
327 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
328 const struct exception_table_entry *entry;
329
330 switch(kcb->kprobe_status) {
331 case KPROBE_HIT_SS:
332 case KPROBE_REENTER:
333 /*
334 * We are here because the instruction being single
335 * stepped caused a page fault. We reset the current
336 * kprobe and the tpc points back to the probe address
337 * and allow the page fault handler to continue as a
338 * normal page fault.
339 */
340 regs->tpc = (unsigned long)cur->addr;
341 regs->tnpc = kcb->kprobe_orig_tnpc;
342 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
343 kcb->kprobe_orig_tstate_pil);
344 if (kcb->kprobe_status == KPROBE_REENTER)
345 restore_previous_kprobe(kcb);
346 else
347 reset_current_kprobe();
348 preempt_enable_no_resched();
349 break;
350 case KPROBE_HIT_ACTIVE:
351 case KPROBE_HIT_SSDONE:
352 /*
353 * We increment the nmissed count for accounting,
354 * we can also use npre/npostfault count for accounting
355 * these specific fault cases.
356 */
357 kprobes_inc_nmissed_count(cur);
358
359 /*
360 * We come here because instructions in the pre/post
361 * handler caused the page_fault, this could happen
362 * if handler tries to access user space by
363 * copy_from_user(), get_user() etc. Let the
364 * user-specified handler try to fix it first.
365 */
366 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
367 return 1;
368
369 /*
370 * In case the user-specified fault handler returned
371 * zero, try to fix up.
372 */
373
374 entry = search_exception_tables(regs->tpc);
375 if (entry) {
376 regs->tpc = entry->fixup;
377 regs->tnpc = regs->tpc + 4;
378 return 1;
379 }
380
381 /*
382 * fixup_exception() could not handle it,
383 * Let do_page_fault() fix it.
384 */
385 break;
386 default:
387 break;
388 }
389
390 return 0;
391}
392
393/*
394 * Wrapper routine to for handling exceptions.
395 */
396int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
397 unsigned long val, void *data)
398{
399 struct die_args *args = (struct die_args *)data;
400 int ret = NOTIFY_DONE;
401
402 if (args->regs && user_mode(args->regs))
403 return ret;
404
405 switch (val) {
406 case DIE_DEBUG:
407 if (kprobe_handler(args->regs))
408 ret = NOTIFY_STOP;
409 break;
410 case DIE_DEBUG_2:
411 if (post_kprobe_handler(args->regs))
412 ret = NOTIFY_STOP;
413 break;
414 default:
415 break;
416 }
417 return ret;
418}
419
420asmlinkage void __kprobes kprobe_trap(unsigned long trap_level,
421 struct pt_regs *regs)
422{
423 enum ctx_state prev_state = exception_enter();
424
425 BUG_ON(trap_level != 0x170 && trap_level != 0x171);
426
427 if (user_mode(regs)) {
428 local_irq_enable();
429 bad_trap(regs, trap_level);
430 goto out;
431 }
432
433 /* trap_level == 0x170 --> ta 0x70
434 * trap_level == 0x171 --> ta 0x71
435 */
436 if (notify_die((trap_level == 0x170) ? DIE_DEBUG : DIE_DEBUG_2,
437 (trap_level == 0x170) ? "debug" : "debug_2",
438 regs, 0, trap_level, SIGTRAP) != NOTIFY_STOP)
439 bad_trap(regs, trap_level);
440out:
441 exception_exit(prev_state);
442}
443
444/* Jprobes support. */
445int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
446{
447 struct jprobe *jp = container_of(p, struct jprobe, kp);
448 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
449
450 memcpy(&(kcb->jprobe_saved_regs), regs, sizeof(*regs));
451
452 regs->tpc = (unsigned long) jp->entry;
453 regs->tnpc = ((unsigned long) jp->entry) + 0x4UL;
454 regs->tstate |= TSTATE_PIL;
455
456 return 1;
457}
458
459void __kprobes jprobe_return(void)
460{
461 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
462 register unsigned long orig_fp asm("g1");
463
464 orig_fp = kcb->jprobe_saved_regs.u_regs[UREG_FP];
465 __asm__ __volatile__("\n"
466"1: cmp %%sp, %0\n\t"
467 "blu,a,pt %%xcc, 1b\n\t"
468 " restore\n\t"
469 ".globl jprobe_return_trap_instruction\n"
470"jprobe_return_trap_instruction:\n\t"
471 "ta 0x70"
472 : /* no outputs */
473 : "r" (orig_fp));
474}
475
476extern void jprobe_return_trap_instruction(void);
477
478int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
479{
480 u32 *addr = (u32 *) regs->tpc;
481 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
482
483 if (addr == (u32 *) jprobe_return_trap_instruction) {
484 memcpy(regs, &(kcb->jprobe_saved_regs), sizeof(*regs));
485 preempt_enable_no_resched();
486 return 1;
487 }
488 return 0;
489}
490
491/* The value stored in the return address register is actually 2
492 * instructions before where the callee will return to.
493 * Sequences usually look something like this
494 *
495 * call some_function <--- return register points here
496 * nop <--- call delay slot
497 * whatever <--- where callee returns to
498 *
499 * To keep trampoline_probe_handler logic simpler, we normalize the
500 * value kept in ri->ret_addr so we don't need to keep adjusting it
501 * back and forth.
502 */
503void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
504 struct pt_regs *regs)
505{
506 ri->ret_addr = (kprobe_opcode_t *)(regs->u_regs[UREG_RETPC] + 8);
507
508 /* Replace the return addr with trampoline addr */
509 regs->u_regs[UREG_RETPC] =
510 ((unsigned long)kretprobe_trampoline) - 8;
511}
512
513/*
514 * Called when the probe at kretprobe trampoline is hit
515 */
516static int __kprobes trampoline_probe_handler(struct kprobe *p,
517 struct pt_regs *regs)
518{
519 struct kretprobe_instance *ri = NULL;
520 struct hlist_head *head, empty_rp;
521 struct hlist_node *tmp;
522 unsigned long flags, orig_ret_address = 0;
523 unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;
524
525 INIT_HLIST_HEAD(&empty_rp);
526 kretprobe_hash_lock(current, &head, &flags);
527
528 /*
529 * It is possible to have multiple instances associated with a given
530 * task either because an multiple functions in the call path
531 * have a return probe installed on them, and/or more than one return
532 * return probe was registered for a target function.
533 *
534 * We can handle this because:
535 * - instances are always inserted at the head of the list
536 * - when multiple return probes are registered for the same
537 * function, the first instance's ret_addr will point to the
538 * real return address, and all the rest will point to
539 * kretprobe_trampoline
540 */
541 hlist_for_each_entry_safe(ri, tmp, head, hlist) {
542 if (ri->task != current)
543 /* another task is sharing our hash bucket */
544 continue;
545
546 if (ri->rp && ri->rp->handler)
547 ri->rp->handler(ri, regs);
548
549 orig_ret_address = (unsigned long)ri->ret_addr;
550 recycle_rp_inst(ri, &empty_rp);
551
552 if (orig_ret_address != trampoline_address)
553 /*
554 * This is the real return address. Any other
555 * instances associated with this task are for
556 * other calls deeper on the call stack
557 */
558 break;
559 }
560
561 kretprobe_assert(ri, orig_ret_address, trampoline_address);
562 regs->tpc = orig_ret_address;
563 regs->tnpc = orig_ret_address + 4;
564
565 reset_current_kprobe();
566 kretprobe_hash_unlock(current, &flags);
567 preempt_enable_no_resched();
568
569 hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
570 hlist_del(&ri->hlist);
571 kfree(ri);
572 }
573 /*
574 * By returning a non-zero value, we are telling
575 * kprobe_handler() that we don't want the post_handler
576 * to run (and have re-enabled preemption)
577 */
578 return 1;
579}
580
581static void __used kretprobe_trampoline_holder(void)
582{
583 asm volatile(".global kretprobe_trampoline\n"
584 "kretprobe_trampoline:\n"
585 "\tnop\n"
586 "\tnop\n");
587}
588static struct kprobe trampoline_p = {
589 .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
590 .pre_handler = trampoline_probe_handler
591};
592
593int __init arch_init_kprobes(void)
594{
595 return register_kprobe(&trampoline_p);
596}
597
598int __kprobes arch_trampoline_kprobe(struct kprobe *p)
599{
600 if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
601 return 1;
602
603 return 0;
604}
1// SPDX-License-Identifier: GPL-2.0
2/* arch/sparc64/kernel/kprobes.c
3 *
4 * Copyright (C) 2004 David S. Miller <davem@davemloft.net>
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/* We do not have hardware single-stepping on sparc64.
18 * So we implement software single-stepping with breakpoint
19 * traps. The top-level scheme is similar to that used
20 * in the x86 kprobes implementation.
21 *
22 * In the kprobe->ainsn.insn[] array we store the original
23 * instruction at index zero and a break instruction at
24 * index one.
25 *
26 * When we hit a kprobe we:
27 * - Run the pre-handler
28 * - Remember "regs->tnpc" and interrupt level stored in
29 * "regs->tstate" so we can restore them later
30 * - Disable PIL interrupts
31 * - Set regs->tpc to point to kprobe->ainsn.insn[0]
32 * - Set regs->tnpc to point to kprobe->ainsn.insn[1]
33 * - Mark that we are actively in a kprobe
34 *
35 * At this point we wait for the second breakpoint at
36 * kprobe->ainsn.insn[1] to hit. When it does we:
37 * - Run the post-handler
38 * - Set regs->tpc to "remembered" regs->tnpc stored above,
39 * restore the PIL interrupt level in "regs->tstate" as well
40 * - Make any adjustments necessary to regs->tnpc in order
41 * to handle relative branches correctly. See below.
42 * - Mark that we are no longer actively in a kprobe.
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 /*single step inline, if it a breakpoint instruction*/
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 * We don't want to be preempted for the entire
125 * duration of kprobe processing
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 /* We have reentered the kprobe_handler(), since
139 * another probe was hit while within the handler.
140 * We here save the original kprobes variables and
141 * just single step on the instruction of the new probe
142 * without calling any user handlers.
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 /* The breakpoint instruction was removed by
152 * another cpu right after we hit, no further
153 * handling of this interrupt is appropriate
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 * The breakpoint instruction was removed right
165 * after we hit it. Another cpu has removed
166 * either a probepoint or a debugger breakpoint
167 * at this address. In either case, no further
168 * handling of this interrupt is appropriate.
169 */
170 ret = 1;
171 }
172 /* Not one of ours: let kernel handle it */
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/* If INSN is a relative control transfer instruction,
194 * return the corrected branch destination value.
195 *
196 * regs->tpc and regs->tnpc still hold the values of the
197 * program counters at the time of trap due to the execution
198 * of the BREAKPOINT_INSTRUCTION_2 at p->ainsn.insn[1]
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 /* Branch not taken, no mods necessary. */
207 if (regs->tnpc == regs->tpc + 0x4UL)
208 return real_pc + 0x8UL;
209
210 /* The three cases are call, branch w/prediction,
211 * and traditional branch.
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 /* The instruction did all the work for us
221 * already, just apply the offset to the correct
222 * instruction location.
223 */
224 return (real_pc + (regs->tnpc - ainsn_addr));
225 }
226
227 /* It is jmpl or some other absolute PC modification instruction,
228 * leave NPC as-is.
229 */
230 return regs->tnpc;
231}
232
233/* If INSN is an instruction which writes it's PC location
234 * into a destination register, fix that up.
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 /* Simplest case is 'call', which always uses %o7 */
242 if ((insn & 0xc0000000) == 0x40000000) {
243 slot = ®s->u_regs[UREG_I7];
244 }
245
246 /* 'jmpl' encodes the register inside of the opcode */
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 /* Hard case, it goes onto the stack. */
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 * Called after single-stepping. p->addr is the address of the
268 * instruction which has been replaced by the breakpoint
269 * instruction. To avoid the SMP problems that can occur when we
270 * temporarily put back the original opcode to single-step, we
271 * single-stepped a copy of the instruction. The address of this
272 * copy is &p->ainsn.insn[0].
273 *
274 * This function prepares to return from the post-single-step
275 * breakpoint trap.
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 /* This assignment must occur after relbranch_fixup() */
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 /*Restore back the original saved kprobes variables and continue. */
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 * We are here because the instruction being single
331 * stepped caused a page fault. We reset the current
332 * kprobe and the tpc points back to the probe address
333 * and allow the page fault handler to continue as a
334 * normal page fault.
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 * In case the user-specified fault handler returned
350 * zero, try to fix up.
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 * fixup_exception() could not handle it,
362 * Let do_page_fault() fix it.
363 */
364 break;
365 default:
366 break;
367 }
368
369 return 0;
370}
371
372/*
373 * Wrapper routine to for handling exceptions.
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 /* trap_level == 0x170 --> ta 0x70
413 * trap_level == 0x171 --> ta 0x71
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/* The value stored in the return address register is actually 2
424 * instructions before where the callee will return to.
425 * Sequences usually look something like this
426 *
427 * call some_function <--- return register points here
428 * nop <--- call delay slot
429 * whatever <--- where callee returns to
430 *
431 * To keep trampoline_probe_handler logic simpler, we normalize the
432 * value kept in ri->ret_addr so we don't need to keep adjusting it
433 * back and forth.
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 /* Replace the return addr with trampoline addr */
442 regs->u_regs[UREG_RETPC] =
443 ((unsigned long)__kretprobe_trampoline) - 8;
444}
445
446/*
447 * Called when the probe at kretprobe trampoline is hit
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, NULL);
455 regs->tpc = orig_ret_address;
456 regs->tnpc = orig_ret_address + 4;
457
458 /*
459 * By returning a non-zero value, we are telling
460 * kprobe_handler() that we don't want the post_handler
461 * to run (and have re-enabled preemption)
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}