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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/* 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 <linux/context_tracking.h>
12#include <asm/signal.h>
13#include <asm/cacheflush.h>
14#include <asm/uaccess.h>
15
16/* We do not have hardware single-stepping on sparc64.
17 * So we implement software single-stepping with breakpoint
18 * traps. The top-level scheme is similar to that used
19 * in the x86 kprobes implementation.
20 *
21 * In the kprobe->ainsn.insn[] array we store the original
22 * instruction at index zero and a break instruction at
23 * index one.
24 *
25 * When we hit a kprobe we:
26 * - Run the pre-handler
27 * - Remember "regs->tnpc" and interrupt level stored in
28 * "regs->tstate" so we can restore them later
29 * - Disable PIL interrupts
30 * - Set regs->tpc to point to kprobe->ainsn.insn[0]
31 * - Set regs->tnpc to point to kprobe->ainsn.insn[1]
32 * - Mark that we are actively in a kprobe
33 *
34 * At this point we wait for the second breakpoint at
35 * kprobe->ainsn.insn[1] to hit. When it does we:
36 * - Run the post-handler
37 * - Set regs->tpc to "remembered" regs->tnpc stored above,
38 * restore the PIL interrupt level in "regs->tstate" as well
39 * - Make any adjustments necessary to regs->tnpc in order
40 * to handle relative branches correctly. See below.
41 * - Mark that we are no longer actively in a kprobe.
42 */
43
44DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
45DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
46
47struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
48
49int __kprobes arch_prepare_kprobe(struct kprobe *p)
50{
51 if ((unsigned long) p->addr & 0x3UL)
52 return -EILSEQ;
53
54 p->ainsn.insn[0] = *p->addr;
55 flushi(&p->ainsn.insn[0]);
56
57 p->ainsn.insn[1] = BREAKPOINT_INSTRUCTION_2;
58 flushi(&p->ainsn.insn[1]);
59
60 p->opcode = *p->addr;
61 return 0;
62}
63
64void __kprobes arch_arm_kprobe(struct kprobe *p)
65{
66 *p->addr = BREAKPOINT_INSTRUCTION;
67 flushi(p->addr);
68}
69
70void __kprobes arch_disarm_kprobe(struct kprobe *p)
71{
72 *p->addr = p->opcode;
73 flushi(p->addr);
74}
75
76static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
77{
78 kcb->prev_kprobe.kp = kprobe_running();
79 kcb->prev_kprobe.status = kcb->kprobe_status;
80 kcb->prev_kprobe.orig_tnpc = kcb->kprobe_orig_tnpc;
81 kcb->prev_kprobe.orig_tstate_pil = kcb->kprobe_orig_tstate_pil;
82}
83
84static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
85{
86 __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
87 kcb->kprobe_status = kcb->prev_kprobe.status;
88 kcb->kprobe_orig_tnpc = kcb->prev_kprobe.orig_tnpc;
89 kcb->kprobe_orig_tstate_pil = kcb->prev_kprobe.orig_tstate_pil;
90}
91
92static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
93 struct kprobe_ctlblk *kcb)
94{
95 __this_cpu_write(current_kprobe, p);
96 kcb->kprobe_orig_tnpc = regs->tnpc;
97 kcb->kprobe_orig_tstate_pil = (regs->tstate & TSTATE_PIL);
98}
99
100static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs,
101 struct kprobe_ctlblk *kcb)
102{
103 regs->tstate |= TSTATE_PIL;
104
105 /*single step inline, if it a breakpoint instruction*/
106 if (p->opcode == BREAKPOINT_INSTRUCTION) {
107 regs->tpc = (unsigned long) p->addr;
108 regs->tnpc = kcb->kprobe_orig_tnpc;
109 } else {
110 regs->tpc = (unsigned long) &p->ainsn.insn[0];
111 regs->tnpc = (unsigned long) &p->ainsn.insn[1];
112 }
113}
114
115static int __kprobes kprobe_handler(struct pt_regs *regs)
116{
117 struct kprobe *p;
118 void *addr = (void *) regs->tpc;
119 int ret = 0;
120 struct kprobe_ctlblk *kcb;
121
122 /*
123 * We don't want to be preempted for the entire
124 * duration of kprobe processing
125 */
126 preempt_disable();
127 kcb = get_kprobe_ctlblk();
128
129 if (kprobe_running()) {
130 p = get_kprobe(addr);
131 if (p) {
132 if (kcb->kprobe_status == KPROBE_HIT_SS) {
133 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
134 kcb->kprobe_orig_tstate_pil);
135 goto no_kprobe;
136 }
137 /* We have reentered the kprobe_handler(), since
138 * another probe was hit while within the handler.
139 * We here save the original kprobes variables and
140 * just single step on the instruction of the new probe
141 * without calling any user handlers.
142 */
143 save_previous_kprobe(kcb);
144 set_current_kprobe(p, regs, kcb);
145 kprobes_inc_nmissed_count(p);
146 kcb->kprobe_status = KPROBE_REENTER;
147 prepare_singlestep(p, regs, kcb);
148 return 1;
149 } else {
150 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 goto no_kprobe;
157 }
158 p = __this_cpu_read(current_kprobe);
159 if (p->break_handler && p->break_handler(p, regs))
160 goto ss_probe;
161 }
162 goto no_kprobe;
163 }
164
165 p = get_kprobe(addr);
166 if (!p) {
167 if (*(u32 *)addr != BREAKPOINT_INSTRUCTION) {
168 /*
169 * The breakpoint instruction was removed right
170 * after we hit it. Another cpu has removed
171 * either a probepoint or a debugger breakpoint
172 * at this address. In either case, no further
173 * handling of this interrupt is appropriate.
174 */
175 ret = 1;
176 }
177 /* Not one of ours: let kernel handle it */
178 goto no_kprobe;
179 }
180
181 set_current_kprobe(p, regs, kcb);
182 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
183 if (p->pre_handler && p->pre_handler(p, regs))
184 return 1;
185
186ss_probe:
187 prepare_singlestep(p, regs, kcb);
188 kcb->kprobe_status = KPROBE_HIT_SS;
189 return 1;
190
191no_kprobe:
192 preempt_enable_no_resched();
193 return ret;
194}
195
196/* If INSN is a relative control transfer instruction,
197 * return the corrected branch destination value.
198 *
199 * regs->tpc and regs->tnpc still hold the values of the
200 * program counters at the time of trap due to the execution
201 * of the BREAKPOINT_INSTRUCTION_2 at p->ainsn.insn[1]
202 *
203 */
204static unsigned long __kprobes relbranch_fixup(u32 insn, struct kprobe *p,
205 struct pt_regs *regs)
206{
207 unsigned long real_pc = (unsigned long) p->addr;
208
209 /* Branch not taken, no mods necessary. */
210 if (regs->tnpc == regs->tpc + 0x4UL)
211 return real_pc + 0x8UL;
212
213 /* The three cases are call, branch w/prediction,
214 * and traditional branch.
215 */
216 if ((insn & 0xc0000000) == 0x40000000 ||
217 (insn & 0xc1c00000) == 0x00400000 ||
218 (insn & 0xc1c00000) == 0x00800000) {
219 unsigned long ainsn_addr;
220
221 ainsn_addr = (unsigned long) &p->ainsn.insn[0];
222
223 /* The instruction did all the work for us
224 * already, just apply the offset to the correct
225 * instruction location.
226 */
227 return (real_pc + (regs->tnpc - ainsn_addr));
228 }
229
230 /* It is jmpl or some other absolute PC modification instruction,
231 * leave NPC as-is.
232 */
233 return regs->tnpc;
234}
235
236/* If INSN is an instruction which writes it's PC location
237 * into a destination register, fix that up.
238 */
239static void __kprobes retpc_fixup(struct pt_regs *regs, u32 insn,
240 unsigned long real_pc)
241{
242 unsigned long *slot = NULL;
243
244 /* Simplest case is 'call', which always uses %o7 */
245 if ((insn & 0xc0000000) == 0x40000000) {
246 slot = ®s->u_regs[UREG_I7];
247 }
248
249 /* 'jmpl' encodes the register inside of the opcode */
250 if ((insn & 0xc1f80000) == 0x81c00000) {
251 unsigned long rd = ((insn >> 25) & 0x1f);
252
253 if (rd <= 15) {
254 slot = ®s->u_regs[rd];
255 } else {
256 /* Hard case, it goes onto the stack. */
257 flushw_all();
258
259 rd -= 16;
260 slot = (unsigned long *)
261 (regs->u_regs[UREG_FP] + STACK_BIAS);
262 slot += rd;
263 }
264 }
265 if (slot != NULL)
266 *slot = real_pc;
267}
268
269/*
270 * Called after single-stepping. p->addr is the address of the
271 * instruction which has been replaced by the breakpoint
272 * instruction. To avoid the SMP problems that can occur when we
273 * temporarily put back the original opcode to single-step, we
274 * single-stepped a copy of the instruction. The address of this
275 * copy is &p->ainsn.insn[0].
276 *
277 * This function prepares to return from the post-single-step
278 * breakpoint trap.
279 */
280static void __kprobes resume_execution(struct kprobe *p,
281 struct pt_regs *regs, struct kprobe_ctlblk *kcb)
282{
283 u32 insn = p->ainsn.insn[0];
284
285 regs->tnpc = relbranch_fixup(insn, p, regs);
286
287 /* This assignment must occur after relbranch_fixup() */
288 regs->tpc = kcb->kprobe_orig_tnpc;
289
290 retpc_fixup(regs, insn, (unsigned long) p->addr);
291
292 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
293 kcb->kprobe_orig_tstate_pil);
294}
295
296static int __kprobes post_kprobe_handler(struct pt_regs *regs)
297{
298 struct kprobe *cur = kprobe_running();
299 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
300
301 if (!cur)
302 return 0;
303
304 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
305 kcb->kprobe_status = KPROBE_HIT_SSDONE;
306 cur->post_handler(cur, regs, 0);
307 }
308
309 resume_execution(cur, regs, kcb);
310
311 /*Restore back the original saved kprobes variables and continue. */
312 if (kcb->kprobe_status == KPROBE_REENTER) {
313 restore_previous_kprobe(kcb);
314 goto out;
315 }
316 reset_current_kprobe();
317out:
318 preempt_enable_no_resched();
319
320 return 1;
321}
322
323int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
324{
325 struct kprobe *cur = kprobe_running();
326 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
327 const struct exception_table_entry *entry;
328
329 switch(kcb->kprobe_status) {
330 case KPROBE_HIT_SS:
331 case KPROBE_REENTER:
332 /*
333 * We are here because the instruction being single
334 * stepped caused a page fault. We reset the current
335 * kprobe and the tpc points back to the probe address
336 * and allow the page fault handler to continue as a
337 * normal page fault.
338 */
339 regs->tpc = (unsigned long)cur->addr;
340 regs->tnpc = kcb->kprobe_orig_tnpc;
341 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
342 kcb->kprobe_orig_tstate_pil);
343 if (kcb->kprobe_status == KPROBE_REENTER)
344 restore_previous_kprobe(kcb);
345 else
346 reset_current_kprobe();
347 preempt_enable_no_resched();
348 break;
349 case KPROBE_HIT_ACTIVE:
350 case KPROBE_HIT_SSDONE:
351 /*
352 * We increment the nmissed count for accounting,
353 * we can also use npre/npostfault count for accounting
354 * these specific fault cases.
355 */
356 kprobes_inc_nmissed_count(cur);
357
358 /*
359 * We come here because instructions in the pre/post
360 * handler caused the page_fault, this could happen
361 * if handler tries to access user space by
362 * copy_from_user(), get_user() etc. Let the
363 * user-specified handler try to fix it first.
364 */
365 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
366 return 1;
367
368 /*
369 * In case the user-specified fault handler returned
370 * zero, try to fix up.
371 */
372
373 entry = search_exception_tables(regs->tpc);
374 if (entry) {
375 regs->tpc = entry->fixup;
376 regs->tnpc = regs->tpc + 4;
377 return 1;
378 }
379
380 /*
381 * fixup_exception() could not handle it,
382 * Let do_page_fault() fix it.
383 */
384 break;
385 default:
386 break;
387 }
388
389 return 0;
390}
391
392/*
393 * Wrapper routine to for handling exceptions.
394 */
395int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
396 unsigned long val, void *data)
397{
398 struct die_args *args = (struct die_args *)data;
399 int ret = NOTIFY_DONE;
400
401 if (args->regs && user_mode(args->regs))
402 return ret;
403
404 switch (val) {
405 case DIE_DEBUG:
406 if (kprobe_handler(args->regs))
407 ret = NOTIFY_STOP;
408 break;
409 case DIE_DEBUG_2:
410 if (post_kprobe_handler(args->regs))
411 ret = NOTIFY_STOP;
412 break;
413 default:
414 break;
415 }
416 return ret;
417}
418
419asmlinkage void __kprobes kprobe_trap(unsigned long trap_level,
420 struct pt_regs *regs)
421{
422 enum ctx_state prev_state = exception_enter();
423
424 BUG_ON(trap_level != 0x170 && trap_level != 0x171);
425
426 if (user_mode(regs)) {
427 local_irq_enable();
428 bad_trap(regs, trap_level);
429 goto out;
430 }
431
432 /* trap_level == 0x170 --> ta 0x70
433 * trap_level == 0x171 --> ta 0x71
434 */
435 if (notify_die((trap_level == 0x170) ? DIE_DEBUG : DIE_DEBUG_2,
436 (trap_level == 0x170) ? "debug" : "debug_2",
437 regs, 0, trap_level, SIGTRAP) != NOTIFY_STOP)
438 bad_trap(regs, trap_level);
439out:
440 exception_exit(prev_state);
441}
442
443/* Jprobes support. */
444int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
445{
446 struct jprobe *jp = container_of(p, struct jprobe, kp);
447 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
448
449 memcpy(&(kcb->jprobe_saved_regs), regs, sizeof(*regs));
450
451 regs->tpc = (unsigned long) jp->entry;
452 regs->tnpc = ((unsigned long) jp->entry) + 0x4UL;
453 regs->tstate |= TSTATE_PIL;
454
455 return 1;
456}
457
458void __kprobes jprobe_return(void)
459{
460 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
461 register unsigned long orig_fp asm("g1");
462
463 orig_fp = kcb->jprobe_saved_regs.u_regs[UREG_FP];
464 __asm__ __volatile__("\n"
465"1: cmp %%sp, %0\n\t"
466 "blu,a,pt %%xcc, 1b\n\t"
467 " restore\n\t"
468 ".globl jprobe_return_trap_instruction\n"
469"jprobe_return_trap_instruction:\n\t"
470 "ta 0x70"
471 : /* no outputs */
472 : "r" (orig_fp));
473}
474
475extern void jprobe_return_trap_instruction(void);
476
477int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
478{
479 u32 *addr = (u32 *) regs->tpc;
480 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
481
482 if (addr == (u32 *) jprobe_return_trap_instruction) {
483 memcpy(regs, &(kcb->jprobe_saved_regs), sizeof(*regs));
484 preempt_enable_no_resched();
485 return 1;
486 }
487 return 0;
488}
489
490/* The value stored in the return address register is actually 2
491 * instructions before where the callee will return to.
492 * Sequences usually look something like this
493 *
494 * call some_function <--- return register points here
495 * nop <--- call delay slot
496 * whatever <--- where callee returns to
497 *
498 * To keep trampoline_probe_handler logic simpler, we normalize the
499 * value kept in ri->ret_addr so we don't need to keep adjusting it
500 * back and forth.
501 */
502void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
503 struct pt_regs *regs)
504{
505 ri->ret_addr = (kprobe_opcode_t *)(regs->u_regs[UREG_RETPC] + 8);
506
507 /* Replace the return addr with trampoline addr */
508 regs->u_regs[UREG_RETPC] =
509 ((unsigned long)kretprobe_trampoline) - 8;
510}
511
512/*
513 * Called when the probe at kretprobe trampoline is hit
514 */
515static int __kprobes trampoline_probe_handler(struct kprobe *p,
516 struct pt_regs *regs)
517{
518 struct kretprobe_instance *ri = NULL;
519 struct hlist_head *head, empty_rp;
520 struct hlist_node *tmp;
521 unsigned long flags, orig_ret_address = 0;
522 unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;
523
524 INIT_HLIST_HEAD(&empty_rp);
525 kretprobe_hash_lock(current, &head, &flags);
526
527 /*
528 * It is possible to have multiple instances associated with a given
529 * task either because an multiple functions in the call path
530 * have a return probe installed on them, and/or more than one return
531 * return probe was registered for a target function.
532 *
533 * We can handle this because:
534 * - instances are always inserted at the head of the list
535 * - when multiple return probes are registered for the same
536 * function, the first instance's ret_addr will point to the
537 * real return address, and all the rest will point to
538 * kretprobe_trampoline
539 */
540 hlist_for_each_entry_safe(ri, tmp, head, hlist) {
541 if (ri->task != current)
542 /* another task is sharing our hash bucket */
543 continue;
544
545 if (ri->rp && ri->rp->handler)
546 ri->rp->handler(ri, regs);
547
548 orig_ret_address = (unsigned long)ri->ret_addr;
549 recycle_rp_inst(ri, &empty_rp);
550
551 if (orig_ret_address != trampoline_address)
552 /*
553 * This is the real return address. Any other
554 * instances associated with this task are for
555 * other calls deeper on the call stack
556 */
557 break;
558 }
559
560 kretprobe_assert(ri, orig_ret_address, trampoline_address);
561 regs->tpc = orig_ret_address;
562 regs->tnpc = orig_ret_address + 4;
563
564 reset_current_kprobe();
565 kretprobe_hash_unlock(current, &flags);
566 preempt_enable_no_resched();
567
568 hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
569 hlist_del(&ri->hlist);
570 kfree(ri);
571 }
572 /*
573 * By returning a non-zero value, we are telling
574 * kprobe_handler() that we don't want the post_handler
575 * to run (and have re-enabled preemption)
576 */
577 return 1;
578}
579
580static void __used kretprobe_trampoline_holder(void)
581{
582 asm volatile(".global kretprobe_trampoline\n"
583 "kretprobe_trampoline:\n"
584 "\tnop\n"
585 "\tnop\n");
586}
587static struct kprobe trampoline_p = {
588 .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
589 .pre_handler = trampoline_probe_handler
590};
591
592int __init arch_init_kprobes(void)
593{
594 return register_kprobe(&trampoline_p);
595}
596
597int __kprobes arch_trampoline_kprobe(struct kprobe *p)
598{
599 if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
600 return 1;
601
602 return 0;
603}