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1/* arch/sparc64/kernel/kprobes.c
2 *
3 * Copyright (C) 2004 David S. Miller <davem@davemloft.net>
4 */
5
6#include <linux/kernel.h>
7#include <linux/kprobes.h>
8#include <linux/module.h>
9#include <linux/kdebug.h>
10#include <linux/slab.h>
11#include <asm/signal.h>
12#include <asm/cacheflush.h>
13#include <asm/uaccess.h>
14
15/* We do not have hardware single-stepping on sparc64.
16 * So we implement software single-stepping with breakpoint
17 * traps. The top-level scheme is similar to that used
18 * in the x86 kprobes implementation.
19 *
20 * In the kprobe->ainsn.insn[] array we store the original
21 * instruction at index zero and a break instruction at
22 * index one.
23 *
24 * When we hit a kprobe we:
25 * - Run the pre-handler
26 * - Remember "regs->tnpc" and interrupt level stored in
27 * "regs->tstate" so we can restore them later
28 * - Disable PIL interrupts
29 * - Set regs->tpc to point to kprobe->ainsn.insn[0]
30 * - Set regs->tnpc to point to kprobe->ainsn.insn[1]
31 * - Mark that we are actively in a kprobe
32 *
33 * At this point we wait for the second breakpoint at
34 * kprobe->ainsn.insn[1] to hit. When it does we:
35 * - Run the post-handler
36 * - Set regs->tpc to "remembered" regs->tnpc stored above,
37 * restore the PIL interrupt level in "regs->tstate" as well
38 * - Make any adjustments necessary to regs->tnpc in order
39 * to handle relative branches correctly. See below.
40 * - Mark that we are no longer actively in a kprobe.
41 */
42
43DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
44DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
45
46struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
47
48int __kprobes arch_prepare_kprobe(struct kprobe *p)
49{
50 if ((unsigned long) p->addr & 0x3UL)
51 return -EILSEQ;
52
53 p->ainsn.insn[0] = *p->addr;
54 flushi(&p->ainsn.insn[0]);
55
56 p->ainsn.insn[1] = BREAKPOINT_INSTRUCTION_2;
57 flushi(&p->ainsn.insn[1]);
58
59 p->opcode = *p->addr;
60 return 0;
61}
62
63void __kprobes arch_arm_kprobe(struct kprobe *p)
64{
65 *p->addr = BREAKPOINT_INSTRUCTION;
66 flushi(p->addr);
67}
68
69void __kprobes arch_disarm_kprobe(struct kprobe *p)
70{
71 *p->addr = p->opcode;
72 flushi(p->addr);
73}
74
75static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
76{
77 kcb->prev_kprobe.kp = kprobe_running();
78 kcb->prev_kprobe.status = kcb->kprobe_status;
79 kcb->prev_kprobe.orig_tnpc = kcb->kprobe_orig_tnpc;
80 kcb->prev_kprobe.orig_tstate_pil = kcb->kprobe_orig_tstate_pil;
81}
82
83static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
84{
85 __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
86 kcb->kprobe_status = kcb->prev_kprobe.status;
87 kcb->kprobe_orig_tnpc = kcb->prev_kprobe.orig_tnpc;
88 kcb->kprobe_orig_tstate_pil = kcb->prev_kprobe.orig_tstate_pil;
89}
90
91static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
92 struct kprobe_ctlblk *kcb)
93{
94 __get_cpu_var(current_kprobe) = p;
95 kcb->kprobe_orig_tnpc = regs->tnpc;
96 kcb->kprobe_orig_tstate_pil = (regs->tstate & TSTATE_PIL);
97}
98
99static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs,
100 struct kprobe_ctlblk *kcb)
101{
102 regs->tstate |= TSTATE_PIL;
103
104 /*single step inline, if it a breakpoint instruction*/
105 if (p->opcode == BREAKPOINT_INSTRUCTION) {
106 regs->tpc = (unsigned long) p->addr;
107 regs->tnpc = kcb->kprobe_orig_tnpc;
108 } else {
109 regs->tpc = (unsigned long) &p->ainsn.insn[0];
110 regs->tnpc = (unsigned long) &p->ainsn.insn[1];
111 }
112}
113
114static int __kprobes kprobe_handler(struct pt_regs *regs)
115{
116 struct kprobe *p;
117 void *addr = (void *) regs->tpc;
118 int ret = 0;
119 struct kprobe_ctlblk *kcb;
120
121 /*
122 * We don't want to be preempted for the entire
123 * duration of kprobe processing
124 */
125 preempt_disable();
126 kcb = get_kprobe_ctlblk();
127
128 if (kprobe_running()) {
129 p = get_kprobe(addr);
130 if (p) {
131 if (kcb->kprobe_status == KPROBE_HIT_SS) {
132 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
133 kcb->kprobe_orig_tstate_pil);
134 goto no_kprobe;
135 }
136 /* We have reentered the kprobe_handler(), since
137 * another probe was hit while within the handler.
138 * We here save the original kprobes variables and
139 * just single step on the instruction of the new probe
140 * without calling any user handlers.
141 */
142 save_previous_kprobe(kcb);
143 set_current_kprobe(p, regs, kcb);
144 kprobes_inc_nmissed_count(p);
145 kcb->kprobe_status = KPROBE_REENTER;
146 prepare_singlestep(p, regs, kcb);
147 return 1;
148 } else {
149 if (*(u32 *)addr != BREAKPOINT_INSTRUCTION) {
150 /* The breakpoint instruction was removed by
151 * another cpu right after we hit, no further
152 * handling of this interrupt is appropriate
153 */
154 ret = 1;
155 goto no_kprobe;
156 }
157 p = __get_cpu_var(current_kprobe);
158 if (p->break_handler && p->break_handler(p, regs))
159 goto ss_probe;
160 }
161 goto no_kprobe;
162 }
163
164 p = get_kprobe(addr);
165 if (!p) {
166 if (*(u32 *)addr != BREAKPOINT_INSTRUCTION) {
167 /*
168 * The breakpoint instruction was removed right
169 * after we hit it. Another cpu has removed
170 * either a probepoint or a debugger breakpoint
171 * at this address. In either case, no further
172 * handling of this interrupt is appropriate.
173 */
174 ret = 1;
175 }
176 /* Not one of ours: let kernel handle it */
177 goto no_kprobe;
178 }
179
180 set_current_kprobe(p, regs, kcb);
181 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
182 if (p->pre_handler && p->pre_handler(p, regs))
183 return 1;
184
185ss_probe:
186 prepare_singlestep(p, regs, kcb);
187 kcb->kprobe_status = KPROBE_HIT_SS;
188 return 1;
189
190no_kprobe:
191 preempt_enable_no_resched();
192 return ret;
193}
194
195/* If INSN is a relative control transfer instruction,
196 * return the corrected branch destination value.
197 *
198 * regs->tpc and regs->tnpc still hold the values of the
199 * program counters at the time of trap due to the execution
200 * of the BREAKPOINT_INSTRUCTION_2 at p->ainsn.insn[1]
201 *
202 */
203static unsigned long __kprobes relbranch_fixup(u32 insn, struct kprobe *p,
204 struct pt_regs *regs)
205{
206 unsigned long real_pc = (unsigned long) p->addr;
207
208 /* Branch not taken, no mods necessary. */
209 if (regs->tnpc == regs->tpc + 0x4UL)
210 return real_pc + 0x8UL;
211
212 /* The three cases are call, branch w/prediction,
213 * and traditional branch.
214 */
215 if ((insn & 0xc0000000) == 0x40000000 ||
216 (insn & 0xc1c00000) == 0x00400000 ||
217 (insn & 0xc1c00000) == 0x00800000) {
218 unsigned long ainsn_addr;
219
220 ainsn_addr = (unsigned long) &p->ainsn.insn[0];
221
222 /* The instruction did all the work for us
223 * already, just apply the offset to the correct
224 * instruction location.
225 */
226 return (real_pc + (regs->tnpc - ainsn_addr));
227 }
228
229 /* It is jmpl or some other absolute PC modification instruction,
230 * leave NPC as-is.
231 */
232 return regs->tnpc;
233}
234
235/* If INSN is an instruction which writes it's PC location
236 * into a destination register, fix that up.
237 */
238static void __kprobes retpc_fixup(struct pt_regs *regs, u32 insn,
239 unsigned long real_pc)
240{
241 unsigned long *slot = NULL;
242
243 /* Simplest case is 'call', which always uses %o7 */
244 if ((insn & 0xc0000000) == 0x40000000) {
245 slot = ®s->u_regs[UREG_I7];
246 }
247
248 /* 'jmpl' encodes the register inside of the opcode */
249 if ((insn & 0xc1f80000) == 0x81c00000) {
250 unsigned long rd = ((insn >> 25) & 0x1f);
251
252 if (rd <= 15) {
253 slot = ®s->u_regs[rd];
254 } else {
255 /* Hard case, it goes onto the stack. */
256 flushw_all();
257
258 rd -= 16;
259 slot = (unsigned long *)
260 (regs->u_regs[UREG_FP] + STACK_BIAS);
261 slot += rd;
262 }
263 }
264 if (slot != NULL)
265 *slot = real_pc;
266}
267
268/*
269 * Called after single-stepping. p->addr is the address of the
270 * instruction which has been replaced by the breakpoint
271 * instruction. To avoid the SMP problems that can occur when we
272 * temporarily put back the original opcode to single-step, we
273 * single-stepped a copy of the instruction. The address of this
274 * copy is &p->ainsn.insn[0].
275 *
276 * This function prepares to return from the post-single-step
277 * breakpoint trap.
278 */
279static void __kprobes resume_execution(struct kprobe *p,
280 struct pt_regs *regs, struct kprobe_ctlblk *kcb)
281{
282 u32 insn = p->ainsn.insn[0];
283
284 regs->tnpc = relbranch_fixup(insn, p, regs);
285
286 /* This assignment must occur after relbranch_fixup() */
287 regs->tpc = kcb->kprobe_orig_tnpc;
288
289 retpc_fixup(regs, insn, (unsigned long) p->addr);
290
291 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
292 kcb->kprobe_orig_tstate_pil);
293}
294
295static int __kprobes post_kprobe_handler(struct pt_regs *regs)
296{
297 struct kprobe *cur = kprobe_running();
298 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
299
300 if (!cur)
301 return 0;
302
303 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
304 kcb->kprobe_status = KPROBE_HIT_SSDONE;
305 cur->post_handler(cur, regs, 0);
306 }
307
308 resume_execution(cur, regs, kcb);
309
310 /*Restore back the original saved kprobes variables and continue. */
311 if (kcb->kprobe_status == KPROBE_REENTER) {
312 restore_previous_kprobe(kcb);
313 goto out;
314 }
315 reset_current_kprobe();
316out:
317 preempt_enable_no_resched();
318
319 return 1;
320}
321
322int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
323{
324 struct kprobe *cur = kprobe_running();
325 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
326 const struct exception_table_entry *entry;
327
328 switch(kcb->kprobe_status) {
329 case KPROBE_HIT_SS:
330 case KPROBE_REENTER:
331 /*
332 * We are here because the instruction being single
333 * stepped caused a page fault. We reset the current
334 * kprobe and the tpc points back to the probe address
335 * and allow the page fault handler to continue as a
336 * normal page fault.
337 */
338 regs->tpc = (unsigned long)cur->addr;
339 regs->tnpc = kcb->kprobe_orig_tnpc;
340 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
341 kcb->kprobe_orig_tstate_pil);
342 if (kcb->kprobe_status == KPROBE_REENTER)
343 restore_previous_kprobe(kcb);
344 else
345 reset_current_kprobe();
346 preempt_enable_no_resched();
347 break;
348 case KPROBE_HIT_ACTIVE:
349 case KPROBE_HIT_SSDONE:
350 /*
351 * We increment the nmissed count for accounting,
352 * we can also use npre/npostfault count for accouting
353 * these specific fault cases.
354 */
355 kprobes_inc_nmissed_count(cur);
356
357 /*
358 * We come here because instructions in the pre/post
359 * handler caused the page_fault, this could happen
360 * if handler tries to access user space by
361 * copy_from_user(), get_user() etc. Let the
362 * user-specified handler try to fix it first.
363 */
364 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
365 return 1;
366
367 /*
368 * In case the user-specified fault handler returned
369 * zero, try to fix up.
370 */
371
372 entry = search_exception_tables(regs->tpc);
373 if (entry) {
374 regs->tpc = entry->fixup;
375 regs->tnpc = regs->tpc + 4;
376 return 1;
377 }
378
379 /*
380 * fixup_exception() could not handle it,
381 * Let do_page_fault() fix it.
382 */
383 break;
384 default:
385 break;
386 }
387
388 return 0;
389}
390
391/*
392 * Wrapper routine to for handling exceptions.
393 */
394int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
395 unsigned long val, void *data)
396{
397 struct die_args *args = (struct die_args *)data;
398 int ret = NOTIFY_DONE;
399
400 if (args->regs && user_mode(args->regs))
401 return ret;
402
403 switch (val) {
404 case DIE_DEBUG:
405 if (kprobe_handler(args->regs))
406 ret = NOTIFY_STOP;
407 break;
408 case DIE_DEBUG_2:
409 if (post_kprobe_handler(args->regs))
410 ret = NOTIFY_STOP;
411 break;
412 default:
413 break;
414 }
415 return ret;
416}
417
418asmlinkage void __kprobes kprobe_trap(unsigned long trap_level,
419 struct pt_regs *regs)
420{
421 BUG_ON(trap_level != 0x170 && trap_level != 0x171);
422
423 if (user_mode(regs)) {
424 local_irq_enable();
425 bad_trap(regs, trap_level);
426 return;
427 }
428
429 /* trap_level == 0x170 --> ta 0x70
430 * trap_level == 0x171 --> ta 0x71
431 */
432 if (notify_die((trap_level == 0x170) ? DIE_DEBUG : DIE_DEBUG_2,
433 (trap_level == 0x170) ? "debug" : "debug_2",
434 regs, 0, trap_level, SIGTRAP) != NOTIFY_STOP)
435 bad_trap(regs, trap_level);
436}
437
438/* Jprobes support. */
439int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
440{
441 struct jprobe *jp = container_of(p, struct jprobe, kp);
442 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
443
444 memcpy(&(kcb->jprobe_saved_regs), regs, sizeof(*regs));
445
446 regs->tpc = (unsigned long) jp->entry;
447 regs->tnpc = ((unsigned long) jp->entry) + 0x4UL;
448 regs->tstate |= TSTATE_PIL;
449
450 return 1;
451}
452
453void __kprobes jprobe_return(void)
454{
455 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
456 register unsigned long orig_fp asm("g1");
457
458 orig_fp = kcb->jprobe_saved_regs.u_regs[UREG_FP];
459 __asm__ __volatile__("\n"
460"1: cmp %%sp, %0\n\t"
461 "blu,a,pt %%xcc, 1b\n\t"
462 " restore\n\t"
463 ".globl jprobe_return_trap_instruction\n"
464"jprobe_return_trap_instruction:\n\t"
465 "ta 0x70"
466 : /* no outputs */
467 : "r" (orig_fp));
468}
469
470extern void jprobe_return_trap_instruction(void);
471
472int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
473{
474 u32 *addr = (u32 *) regs->tpc;
475 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
476
477 if (addr == (u32 *) jprobe_return_trap_instruction) {
478 memcpy(regs, &(kcb->jprobe_saved_regs), sizeof(*regs));
479 preempt_enable_no_resched();
480 return 1;
481 }
482 return 0;
483}
484
485/* The value stored in the return address register is actually 2
486 * instructions before where the callee will return to.
487 * Sequences usually look something like this
488 *
489 * call some_function <--- return register points here
490 * nop <--- call delay slot
491 * whatever <--- where callee returns to
492 *
493 * To keep trampoline_probe_handler logic simpler, we normalize the
494 * value kept in ri->ret_addr so we don't need to keep adjusting it
495 * back and forth.
496 */
497void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
498 struct pt_regs *regs)
499{
500 ri->ret_addr = (kprobe_opcode_t *)(regs->u_regs[UREG_RETPC] + 8);
501
502 /* Replace the return addr with trampoline addr */
503 regs->u_regs[UREG_RETPC] =
504 ((unsigned long)kretprobe_trampoline) - 8;
505}
506
507/*
508 * Called when the probe at kretprobe trampoline is hit
509 */
510int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
511{
512 struct kretprobe_instance *ri = NULL;
513 struct hlist_head *head, empty_rp;
514 struct hlist_node *node, *tmp;
515 unsigned long flags, orig_ret_address = 0;
516 unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;
517
518 INIT_HLIST_HEAD(&empty_rp);
519 kretprobe_hash_lock(current, &head, &flags);
520
521 /*
522 * It is possible to have multiple instances associated with a given
523 * task either because an multiple functions in the call path
524 * have a return probe installed on them, and/or more than one return
525 * return probe was registered for a target function.
526 *
527 * We can handle this because:
528 * - instances are always inserted at the head of the list
529 * - when multiple return probes are registered for the same
530 * function, the first instance's ret_addr will point to the
531 * real return address, and all the rest will point to
532 * kretprobe_trampoline
533 */
534 hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
535 if (ri->task != current)
536 /* another task is sharing our hash bucket */
537 continue;
538
539 if (ri->rp && ri->rp->handler)
540 ri->rp->handler(ri, regs);
541
542 orig_ret_address = (unsigned long)ri->ret_addr;
543 recycle_rp_inst(ri, &empty_rp);
544
545 if (orig_ret_address != trampoline_address)
546 /*
547 * This is the real return address. Any other
548 * instances associated with this task are for
549 * other calls deeper on the call stack
550 */
551 break;
552 }
553
554 kretprobe_assert(ri, orig_ret_address, trampoline_address);
555 regs->tpc = orig_ret_address;
556 regs->tnpc = orig_ret_address + 4;
557
558 reset_current_kprobe();
559 kretprobe_hash_unlock(current, &flags);
560 preempt_enable_no_resched();
561
562 hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
563 hlist_del(&ri->hlist);
564 kfree(ri);
565 }
566 /*
567 * By returning a non-zero value, we are telling
568 * kprobe_handler() that we don't want the post_handler
569 * to run (and have re-enabled preemption)
570 */
571 return 1;
572}
573
574void kretprobe_trampoline_holder(void)
575{
576 asm volatile(".global kretprobe_trampoline\n"
577 "kretprobe_trampoline:\n"
578 "\tnop\n"
579 "\tnop\n");
580}
581static struct kprobe trampoline_p = {
582 .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
583 .pre_handler = trampoline_probe_handler
584};
585
586int __init arch_init_kprobes(void)
587{
588 return register_kprobe(&trampoline_p);
589}
590
591int __kprobes arch_trampoline_kprobe(struct kprobe *p)
592{
593 if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
594 return 1;
595
596 return 0;
597}
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}