2 * Kernel Probes (KProbes)
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
18 * Copyright (C) IBM Corporation, 2002, 2006
20 * s390 port, used ppc64 as template. Mike Grundy <grundym@us.ibm.com>
23 #include <linux/kprobes.h>
24 #include <linux/ptrace.h>
25 #include <linux/preempt.h>
26 #include <linux/stop_machine.h>
27 #include <linux/kdebug.h>
28 #include <linux/uaccess.h>
29 #include <asm/cacheflush.h>
30 #include <asm/sections.h>
31 #include <linux/module.h>
32 #include <linux/slab.h>
34 DEFINE_PER_CPU(struct kprobe
*, current_kprobe
) = NULL
;
35 DEFINE_PER_CPU(struct kprobe_ctlblk
, kprobe_ctlblk
);
37 struct kretprobe_blackpoint kretprobe_blacklist
[] = {{NULL
, NULL
}};
39 int __kprobes
arch_prepare_kprobe(struct kprobe
*p
)
41 /* Make sure the probe isn't going on a difficult instruction */
42 if (is_prohibited_opcode((kprobe_opcode_t
*) p
->addr
))
45 if ((unsigned long)p
->addr
& 0x01)
48 /* Use the get_insn_slot() facility for correctness */
49 if (!(p
->ainsn
.insn
= get_insn_slot()))
52 memcpy(p
->ainsn
.insn
, p
->addr
, MAX_INSN_SIZE
* sizeof(kprobe_opcode_t
));
54 get_instruction_type(&p
->ainsn
);
59 int __kprobes
is_prohibited_opcode(kprobe_opcode_t
*instruction
)
61 switch (*(__u8
*) instruction
) {
62 case 0x0c: /* bassm */
66 case 0xac: /* stnsm */
67 case 0xad: /* stosm */
70 switch (*(__u16
*) instruction
) {
72 case 0xb25a: /* bsa */
73 case 0xb240: /* bakr */
74 case 0xb258: /* bsg */
77 case 0xb98d: /* epsw */
83 void __kprobes
get_instruction_type(struct arch_specific_insn
*ainsn
)
85 /* default fixup method */
86 ainsn
->fixup
= FIXUP_PSW_NORMAL
;
89 ainsn
->reg
= (*ainsn
->insn
& 0xf0) >> 4;
91 /* save the instruction length (pop 5-5) in bytes */
92 switch (*(__u8
*) (ainsn
->insn
) >> 6) {
105 switch (*(__u8
*) ainsn
->insn
) {
106 case 0x05: /* balr */
107 case 0x0d: /* basr */
108 ainsn
->fixup
= FIXUP_RETURN_REGISTER
;
109 /* if r2 = 0, no branch will be taken */
110 if ((*ainsn
->insn
& 0x0f) == 0)
111 ainsn
->fixup
|= FIXUP_BRANCH_NOT_TAKEN
;
113 case 0x06: /* bctr */
115 ainsn
->fixup
= FIXUP_BRANCH_NOT_TAKEN
;
119 ainsn
->fixup
= FIXUP_RETURN_REGISTER
;
124 case 0x87: /* bxle */
125 ainsn
->fixup
= FIXUP_BRANCH_NOT_TAKEN
;
127 case 0x82: /* lpsw */
128 ainsn
->fixup
= FIXUP_NOT_REQUIRED
;
130 case 0xb2: /* lpswe */
131 if (*(((__u8
*) ainsn
->insn
) + 1) == 0xb2) {
132 ainsn
->fixup
= FIXUP_NOT_REQUIRED
;
135 case 0xa7: /* bras */
136 if ((*ainsn
->insn
& 0x0f) == 0x05) {
137 ainsn
->fixup
|= FIXUP_RETURN_REGISTER
;
141 if ((*ainsn
->insn
& 0x0f) == 0x00 /* larl */
142 || (*ainsn
->insn
& 0x0f) == 0x05) /* brasl */
143 ainsn
->fixup
|= FIXUP_RETURN_REGISTER
;
146 if (*(((__u8
*) ainsn
->insn
) + 5 ) == 0x44 || /* bxhg */
147 *(((__u8
*) ainsn
->insn
) + 5) == 0x45) {/* bxleg */
148 ainsn
->fixup
= FIXUP_BRANCH_NOT_TAKEN
;
151 case 0xe3: /* bctg */
152 if (*(((__u8
*) ainsn
->insn
) + 5) == 0x46) {
153 ainsn
->fixup
= FIXUP_BRANCH_NOT_TAKEN
;
159 static int __kprobes
swap_instruction(void *aref
)
161 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
162 unsigned long status
= kcb
->kprobe_status
;
163 struct ins_replace_args
*args
= aref
;
166 kcb
->kprobe_status
= KPROBE_SWAP_INST
;
167 rc
= probe_kernel_write(args
->ptr
, &args
->new, sizeof(args
->new));
168 kcb
->kprobe_status
= status
;
172 void __kprobes
arch_arm_kprobe(struct kprobe
*p
)
174 struct ins_replace_args args
;
177 args
.old
= p
->opcode
;
178 args
.new = BREAKPOINT_INSTRUCTION
;
179 stop_machine(swap_instruction
, &args
, NULL
);
182 void __kprobes
arch_disarm_kprobe(struct kprobe
*p
)
184 struct ins_replace_args args
;
187 args
.old
= BREAKPOINT_INSTRUCTION
;
188 args
.new = p
->opcode
;
189 stop_machine(swap_instruction
, &args
, NULL
);
192 void __kprobes
arch_remove_kprobe(struct kprobe
*p
)
195 free_insn_slot(p
->ainsn
.insn
, 0);
196 p
->ainsn
.insn
= NULL
;
200 static void __kprobes
prepare_singlestep(struct kprobe
*p
, struct pt_regs
*regs
)
202 per_cr_bits kprobe_per_regs
[1];
204 memset(kprobe_per_regs
, 0, sizeof(per_cr_bits
));
205 regs
->psw
.addr
= (unsigned long)p
->ainsn
.insn
| PSW_ADDR_AMODE
;
207 /* Set up the per control reg info, will pass to lctl */
208 kprobe_per_regs
[0].em_instruction_fetch
= 1;
209 kprobe_per_regs
[0].starting_addr
= (unsigned long)p
->ainsn
.insn
;
210 kprobe_per_regs
[0].ending_addr
= (unsigned long)p
->ainsn
.insn
+ 1;
212 /* Set the PER control regs, turns on single step for this address */
213 __ctl_load(kprobe_per_regs
, 9, 11);
214 regs
->psw
.mask
|= PSW_MASK_PER
;
215 regs
->psw
.mask
&= ~(PSW_MASK_IO
| PSW_MASK_EXT
| PSW_MASK_MCHECK
);
218 static void __kprobes
save_previous_kprobe(struct kprobe_ctlblk
*kcb
)
220 kcb
->prev_kprobe
.kp
= kprobe_running();
221 kcb
->prev_kprobe
.status
= kcb
->kprobe_status
;
222 kcb
->prev_kprobe
.kprobe_saved_imask
= kcb
->kprobe_saved_imask
;
223 memcpy(kcb
->prev_kprobe
.kprobe_saved_ctl
, kcb
->kprobe_saved_ctl
,
224 sizeof(kcb
->kprobe_saved_ctl
));
227 static void __kprobes
restore_previous_kprobe(struct kprobe_ctlblk
*kcb
)
229 __get_cpu_var(current_kprobe
) = kcb
->prev_kprobe
.kp
;
230 kcb
->kprobe_status
= kcb
->prev_kprobe
.status
;
231 kcb
->kprobe_saved_imask
= kcb
->prev_kprobe
.kprobe_saved_imask
;
232 memcpy(kcb
->kprobe_saved_ctl
, kcb
->prev_kprobe
.kprobe_saved_ctl
,
233 sizeof(kcb
->kprobe_saved_ctl
));
236 static void __kprobes
set_current_kprobe(struct kprobe
*p
, struct pt_regs
*regs
,
237 struct kprobe_ctlblk
*kcb
)
239 __get_cpu_var(current_kprobe
) = p
;
240 /* Save the interrupt and per flags */
241 kcb
->kprobe_saved_imask
= regs
->psw
.mask
&
242 (PSW_MASK_PER
| PSW_MASK_IO
| PSW_MASK_EXT
| PSW_MASK_MCHECK
);
243 /* Save the control regs that govern PER */
244 __ctl_store(kcb
->kprobe_saved_ctl
, 9, 11);
247 void __kprobes
arch_prepare_kretprobe(struct kretprobe_instance
*ri
,
248 struct pt_regs
*regs
)
250 ri
->ret_addr
= (kprobe_opcode_t
*) regs
->gprs
[14];
252 /* Replace the return addr with trampoline addr */
253 regs
->gprs
[14] = (unsigned long)&kretprobe_trampoline
;
256 static int __kprobes
kprobe_handler(struct pt_regs
*regs
)
260 unsigned long *addr
= (unsigned long *)
261 ((regs
->psw
.addr
& PSW_ADDR_INSN
) - 2);
262 struct kprobe_ctlblk
*kcb
;
265 * We don't want to be preempted for the entire
266 * duration of kprobe processing
269 kcb
= get_kprobe_ctlblk();
271 /* Check we're not actually recursing */
272 if (kprobe_running()) {
273 p
= get_kprobe(addr
);
275 if (kcb
->kprobe_status
== KPROBE_HIT_SS
&&
276 *p
->ainsn
.insn
== BREAKPOINT_INSTRUCTION
) {
277 regs
->psw
.mask
&= ~PSW_MASK_PER
;
278 regs
->psw
.mask
|= kcb
->kprobe_saved_imask
;
281 /* We have reentered the kprobe_handler(), since
282 * another probe was hit while within the handler.
283 * We here save the original kprobes variables and
284 * just single step on the instruction of the new probe
285 * without calling any user handlers.
287 save_previous_kprobe(kcb
);
288 set_current_kprobe(p
, regs
, kcb
);
289 kprobes_inc_nmissed_count(p
);
290 prepare_singlestep(p
, regs
);
291 kcb
->kprobe_status
= KPROBE_REENTER
;
294 p
= __get_cpu_var(current_kprobe
);
295 if (p
->break_handler
&& p
->break_handler(p
, regs
)) {
302 p
= get_kprobe(addr
);
305 * No kprobe at this address. The fault has not been
306 * caused by a kprobe breakpoint. The race of breakpoint
307 * vs. kprobe remove does not exist because on s390 we
308 * use stop_machine to arm/disarm the breakpoints.
312 kcb
->kprobe_status
= KPROBE_HIT_ACTIVE
;
313 set_current_kprobe(p
, regs
, kcb
);
314 if (p
->pre_handler
&& p
->pre_handler(p
, regs
))
315 /* handler has already set things up, so skip ss setup */
319 if (regs
->psw
.mask
& (PSW_MASK_PER
| PSW_MASK_IO
))
321 prepare_singlestep(p
, regs
);
322 kcb
->kprobe_status
= KPROBE_HIT_SS
;
326 preempt_enable_no_resched();
331 * Function return probe trampoline:
332 * - init_kprobes() establishes a probepoint here
333 * - When the probed function returns, this probe
334 * causes the handlers to fire
336 static void __used
kretprobe_trampoline_holder(void)
338 asm volatile(".global kretprobe_trampoline\n"
339 "kretprobe_trampoline: bcr 0,0\n");
343 * Called when the probe at kretprobe trampoline is hit
345 static int __kprobes
trampoline_probe_handler(struct kprobe
*p
,
346 struct pt_regs
*regs
)
348 struct kretprobe_instance
*ri
= NULL
;
349 struct hlist_head
*head
, empty_rp
;
350 struct hlist_node
*node
, *tmp
;
351 unsigned long flags
, orig_ret_address
= 0;
352 unsigned long trampoline_address
= (unsigned long)&kretprobe_trampoline
;
354 INIT_HLIST_HEAD(&empty_rp
);
355 kretprobe_hash_lock(current
, &head
, &flags
);
358 * It is possible to have multiple instances associated with a given
359 * task either because an multiple functions in the call path
360 * have a return probe installed on them, and/or more than one return
361 * return probe was registered for a target function.
363 * We can handle this because:
364 * - instances are always inserted at the head of the list
365 * - when multiple return probes are registered for the same
366 * function, the first instance's ret_addr will point to the
367 * real return address, and all the rest will point to
368 * kretprobe_trampoline
370 hlist_for_each_entry_safe(ri
, node
, tmp
, head
, hlist
) {
371 if (ri
->task
!= current
)
372 /* another task is sharing our hash bucket */
375 if (ri
->rp
&& ri
->rp
->handler
)
376 ri
->rp
->handler(ri
, regs
);
378 orig_ret_address
= (unsigned long)ri
->ret_addr
;
379 recycle_rp_inst(ri
, &empty_rp
);
381 if (orig_ret_address
!= trampoline_address
) {
383 * This is the real return address. Any other
384 * instances associated with this task are for
385 * other calls deeper on the call stack
390 kretprobe_assert(ri
, orig_ret_address
, trampoline_address
);
391 regs
->psw
.addr
= orig_ret_address
| PSW_ADDR_AMODE
;
393 reset_current_kprobe();
394 kretprobe_hash_unlock(current
, &flags
);
395 preempt_enable_no_resched();
397 hlist_for_each_entry_safe(ri
, node
, tmp
, &empty_rp
, hlist
) {
398 hlist_del(&ri
->hlist
);
402 * By returning a non-zero value, we are telling
403 * kprobe_handler() that we don't want the post_handler
404 * to run (and have re-enabled preemption)
410 * Called after single-stepping. p->addr is the address of the
411 * instruction whose first byte has been replaced by the "breakpoint"
412 * instruction. To avoid the SMP problems that can occur when we
413 * temporarily put back the original opcode to single-step, we
414 * single-stepped a copy of the instruction. The address of this
415 * copy is p->ainsn.insn.
417 static void __kprobes
resume_execution(struct kprobe
*p
, struct pt_regs
*regs
)
419 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
421 regs
->psw
.addr
&= PSW_ADDR_INSN
;
423 if (p
->ainsn
.fixup
& FIXUP_PSW_NORMAL
)
424 regs
->psw
.addr
= (unsigned long)p
->addr
+
425 ((unsigned long)regs
->psw
.addr
-
426 (unsigned long)p
->ainsn
.insn
);
428 if (p
->ainsn
.fixup
& FIXUP_BRANCH_NOT_TAKEN
)
429 if ((unsigned long)regs
->psw
.addr
-
430 (unsigned long)p
->ainsn
.insn
== p
->ainsn
.ilen
)
431 regs
->psw
.addr
= (unsigned long)p
->addr
+ p
->ainsn
.ilen
;
433 if (p
->ainsn
.fixup
& FIXUP_RETURN_REGISTER
)
434 regs
->gprs
[p
->ainsn
.reg
] = ((unsigned long)p
->addr
+
435 (regs
->gprs
[p
->ainsn
.reg
] -
436 (unsigned long)p
->ainsn
.insn
))
439 regs
->psw
.addr
|= PSW_ADDR_AMODE
;
440 /* turn off PER mode */
441 regs
->psw
.mask
&= ~PSW_MASK_PER
;
442 /* Restore the original per control regs */
443 __ctl_load(kcb
->kprobe_saved_ctl
, 9, 11);
444 regs
->psw
.mask
|= kcb
->kprobe_saved_imask
;
447 static int __kprobes
post_kprobe_handler(struct pt_regs
*regs
)
449 struct kprobe
*cur
= kprobe_running();
450 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
455 if ((kcb
->kprobe_status
!= KPROBE_REENTER
) && cur
->post_handler
) {
456 kcb
->kprobe_status
= KPROBE_HIT_SSDONE
;
457 cur
->post_handler(cur
, regs
, 0);
460 resume_execution(cur
, regs
);
462 /*Restore back the original saved kprobes variables and continue. */
463 if (kcb
->kprobe_status
== KPROBE_REENTER
) {
464 restore_previous_kprobe(kcb
);
467 reset_current_kprobe();
468 if (regs
->psw
.mask
& (PSW_MASK_PER
| PSW_MASK_IO
))
471 preempt_enable_no_resched();
474 * if somebody else is singlestepping across a probe point, psw mask
475 * will have PER set, in which case, continue the remaining processing
476 * of do_single_step, as if this is not a probe hit.
478 if (regs
->psw
.mask
& PSW_MASK_PER
) {
485 int __kprobes
kprobe_fault_handler(struct pt_regs
*regs
, int trapnr
)
487 struct kprobe
*cur
= kprobe_running();
488 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
489 const struct exception_table_entry
*entry
;
491 switch(kcb
->kprobe_status
) {
492 case KPROBE_SWAP_INST
:
493 /* We are here because the instruction replacement failed */
498 * We are here because the instruction being single
499 * stepped caused a page fault. We reset the current
500 * kprobe and the nip points back to the probe address
501 * and allow the page fault handler to continue as a
504 regs
->psw
.addr
= (unsigned long)cur
->addr
| PSW_ADDR_AMODE
;
505 regs
->psw
.mask
&= ~PSW_MASK_PER
;
506 regs
->psw
.mask
|= kcb
->kprobe_saved_imask
;
507 if (kcb
->kprobe_status
== KPROBE_REENTER
)
508 restore_previous_kprobe(kcb
);
510 reset_current_kprobe();
511 if (regs
->psw
.mask
& (PSW_MASK_PER
| PSW_MASK_IO
))
514 preempt_enable_no_resched();
516 case KPROBE_HIT_ACTIVE
:
517 case KPROBE_HIT_SSDONE
:
519 * We increment the nmissed count for accounting,
520 * we can also use npre/npostfault count for accouting
521 * these specific fault cases.
523 kprobes_inc_nmissed_count(cur
);
526 * We come here because instructions in the pre/post
527 * handler caused the page_fault, this could happen
528 * if handler tries to access user space by
529 * copy_from_user(), get_user() etc. Let the
530 * user-specified handler try to fix it first.
532 if (cur
->fault_handler
&& cur
->fault_handler(cur
, regs
, trapnr
))
536 * In case the user-specified fault handler returned
537 * zero, try to fix up.
539 entry
= search_exception_tables(regs
->psw
.addr
& PSW_ADDR_INSN
);
541 regs
->psw
.addr
= entry
->fixup
| PSW_ADDR_AMODE
;
546 * fixup_exception() could not handle it,
547 * Let do_page_fault() fix it.
557 * Wrapper routine to for handling exceptions.
559 int __kprobes
kprobe_exceptions_notify(struct notifier_block
*self
,
560 unsigned long val
, void *data
)
562 struct die_args
*args
= (struct die_args
*)data
;
563 int ret
= NOTIFY_DONE
;
567 if (kprobe_handler(args
->regs
))
571 if (post_kprobe_handler(args
->regs
))
575 /* kprobe_running() needs smp_processor_id() */
577 if (kprobe_running() &&
578 kprobe_fault_handler(args
->regs
, args
->trapnr
))
588 int __kprobes
setjmp_pre_handler(struct kprobe
*p
, struct pt_regs
*regs
)
590 struct jprobe
*jp
= container_of(p
, struct jprobe
, kp
);
592 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
594 memcpy(&kcb
->jprobe_saved_regs
, regs
, sizeof(struct pt_regs
));
596 /* setup return addr to the jprobe handler routine */
597 regs
->psw
.addr
= (unsigned long)(jp
->entry
) | PSW_ADDR_AMODE
;
599 /* r14 is the function return address */
600 kcb
->jprobe_saved_r14
= (unsigned long)regs
->gprs
[14];
601 /* r15 is the stack pointer */
602 kcb
->jprobe_saved_r15
= (unsigned long)regs
->gprs
[15];
603 addr
= (unsigned long)kcb
->jprobe_saved_r15
;
605 memcpy(kcb
->jprobes_stack
, (kprobe_opcode_t
*) addr
,
606 MIN_STACK_SIZE(addr
));
610 void __kprobes
jprobe_return(void)
612 asm volatile(".word 0x0002");
615 void __kprobes
jprobe_return_end(void)
617 asm volatile("bcr 0,0");
620 int __kprobes
longjmp_break_handler(struct kprobe
*p
, struct pt_regs
*regs
)
622 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
623 unsigned long stack_addr
= (unsigned long)(kcb
->jprobe_saved_r15
);
625 /* Put the regs back */
626 memcpy(regs
, &kcb
->jprobe_saved_regs
, sizeof(struct pt_regs
));
627 /* put the stack back */
628 memcpy((kprobe_opcode_t
*) stack_addr
, kcb
->jprobes_stack
,
629 MIN_STACK_SIZE(stack_addr
));
630 preempt_enable_no_resched();
634 static struct kprobe trampoline_p
= {
635 .addr
= (kprobe_opcode_t
*) & kretprobe_trampoline
,
636 .pre_handler
= trampoline_probe_handler
639 int __init
arch_init_kprobes(void)
641 return register_kprobe(&trampoline_p
);
644 int __kprobes
arch_trampoline_kprobe(struct kprobe
*p
)
646 if (p
->addr
== (kprobe_opcode_t
*) & kretprobe_trampoline
)