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 <asm/cacheflush.h>
29 #include <asm/sections.h>
30 #include <asm/uaccess.h>
31 #include <linux/module.h>
33 DEFINE_PER_CPU(struct kprobe
*, current_kprobe
) = NULL
;
34 DEFINE_PER_CPU(struct kprobe_ctlblk
, kprobe_ctlblk
);
36 struct kretprobe_blackpoint kretprobe_blacklist
[] = {{NULL
, NULL
}};
38 int __kprobes
arch_prepare_kprobe(struct kprobe
*p
)
40 /* Make sure the probe isn't going on a difficult instruction */
41 if (is_prohibited_opcode((kprobe_opcode_t
*) p
->addr
))
44 if ((unsigned long)p
->addr
& 0x01)
47 /* Use the get_insn_slot() facility for correctness */
48 if (!(p
->ainsn
.insn
= get_insn_slot()))
51 memcpy(p
->ainsn
.insn
, p
->addr
, MAX_INSN_SIZE
* sizeof(kprobe_opcode_t
));
53 get_instruction_type(&p
->ainsn
);
58 int __kprobes
is_prohibited_opcode(kprobe_opcode_t
*instruction
)
60 switch (*(__u8
*) instruction
) {
61 case 0x0c: /* bassm */
67 switch (*(__u16
*) instruction
) {
69 case 0xb25a: /* bsa */
70 case 0xb240: /* bakr */
71 case 0xb258: /* bsg */
79 void __kprobes
get_instruction_type(struct arch_specific_insn
*ainsn
)
81 /* default fixup method */
82 ainsn
->fixup
= FIXUP_PSW_NORMAL
;
85 ainsn
->reg
= (*ainsn
->insn
& 0xf0) >> 4;
87 /* save the instruction length (pop 5-5) in bytes */
88 switch (*(__u8
*) (ainsn
->insn
) >> 6) {
101 switch (*(__u8
*) ainsn
->insn
) {
102 case 0x05: /* balr */
103 case 0x0d: /* basr */
104 ainsn
->fixup
= FIXUP_RETURN_REGISTER
;
105 /* if r2 = 0, no branch will be taken */
106 if ((*ainsn
->insn
& 0x0f) == 0)
107 ainsn
->fixup
|= FIXUP_BRANCH_NOT_TAKEN
;
109 case 0x06: /* bctr */
111 ainsn
->fixup
= FIXUP_BRANCH_NOT_TAKEN
;
115 ainsn
->fixup
= FIXUP_RETURN_REGISTER
;
120 case 0x87: /* bxle */
121 ainsn
->fixup
= FIXUP_BRANCH_NOT_TAKEN
;
123 case 0x82: /* lpsw */
124 ainsn
->fixup
= FIXUP_NOT_REQUIRED
;
126 case 0xb2: /* lpswe */
127 if (*(((__u8
*) ainsn
->insn
) + 1) == 0xb2) {
128 ainsn
->fixup
= FIXUP_NOT_REQUIRED
;
131 case 0xa7: /* bras */
132 if ((*ainsn
->insn
& 0x0f) == 0x05) {
133 ainsn
->fixup
|= FIXUP_RETURN_REGISTER
;
137 if ((*ainsn
->insn
& 0x0f) == 0x00 /* larl */
138 || (*ainsn
->insn
& 0x0f) == 0x05) /* brasl */
139 ainsn
->fixup
|= FIXUP_RETURN_REGISTER
;
142 if (*(((__u8
*) ainsn
->insn
) + 5 ) == 0x44 || /* bxhg */
143 *(((__u8
*) ainsn
->insn
) + 5) == 0x45) {/* bxleg */
144 ainsn
->fixup
= FIXUP_BRANCH_NOT_TAKEN
;
147 case 0xe3: /* bctg */
148 if (*(((__u8
*) ainsn
->insn
) + 5) == 0x46) {
149 ainsn
->fixup
= FIXUP_BRANCH_NOT_TAKEN
;
155 static int __kprobes
swap_instruction(void *aref
)
157 struct ins_replace_args
*args
= aref
;
163 * Text segment is read-only, hence we use stura to bypass dynamic
164 * address translation to exchange the instruction. Since stura
165 * always operates on four bytes, but we only want to exchange two
166 * bytes do some calculations to get things right. In addition we
167 * shall not cross any page boundaries (vmalloc area!) when writing
168 * the new instruction.
170 addr
= (u32
*)((unsigned long)args
->ptr
& -4UL);
171 if ((unsigned long)args
->ptr
& 2)
172 instr
= ((*addr
) & 0xffff0000) | args
->new;
174 instr
= ((*addr
) & 0x0000ffff) | args
->new << 16;
183 : "a" (addr
), "d" (instr
)
189 void __kprobes
arch_arm_kprobe(struct kprobe
*p
)
191 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
192 unsigned long status
= kcb
->kprobe_status
;
193 struct ins_replace_args args
;
196 args
.old
= p
->opcode
;
197 args
.new = BREAKPOINT_INSTRUCTION
;
199 kcb
->kprobe_status
= KPROBE_SWAP_INST
;
200 stop_machine(swap_instruction
, &args
, NULL
);
201 kcb
->kprobe_status
= status
;
204 void __kprobes
arch_disarm_kprobe(struct kprobe
*p
)
206 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
207 unsigned long status
= kcb
->kprobe_status
;
208 struct ins_replace_args args
;
211 args
.old
= BREAKPOINT_INSTRUCTION
;
212 args
.new = p
->opcode
;
214 kcb
->kprobe_status
= KPROBE_SWAP_INST
;
215 stop_machine(swap_instruction
, &args
, NULL
);
216 kcb
->kprobe_status
= status
;
219 void __kprobes
arch_remove_kprobe(struct kprobe
*p
)
222 free_insn_slot(p
->ainsn
.insn
, 0);
223 p
->ainsn
.insn
= NULL
;
227 static void __kprobes
prepare_singlestep(struct kprobe
*p
, struct pt_regs
*regs
)
229 per_cr_bits kprobe_per_regs
[1];
231 memset(kprobe_per_regs
, 0, sizeof(per_cr_bits
));
232 regs
->psw
.addr
= (unsigned long)p
->ainsn
.insn
| PSW_ADDR_AMODE
;
234 /* Set up the per control reg info, will pass to lctl */
235 kprobe_per_regs
[0].em_instruction_fetch
= 1;
236 kprobe_per_regs
[0].starting_addr
= (unsigned long)p
->ainsn
.insn
;
237 kprobe_per_regs
[0].ending_addr
= (unsigned long)p
->ainsn
.insn
+ 1;
239 /* Set the PER control regs, turns on single step for this address */
240 __ctl_load(kprobe_per_regs
, 9, 11);
241 regs
->psw
.mask
|= PSW_MASK_PER
;
242 regs
->psw
.mask
&= ~(PSW_MASK_IO
| PSW_MASK_EXT
| PSW_MASK_MCHECK
);
245 static void __kprobes
save_previous_kprobe(struct kprobe_ctlblk
*kcb
)
247 kcb
->prev_kprobe
.kp
= kprobe_running();
248 kcb
->prev_kprobe
.status
= kcb
->kprobe_status
;
249 kcb
->prev_kprobe
.kprobe_saved_imask
= kcb
->kprobe_saved_imask
;
250 memcpy(kcb
->prev_kprobe
.kprobe_saved_ctl
, kcb
->kprobe_saved_ctl
,
251 sizeof(kcb
->kprobe_saved_ctl
));
254 static void __kprobes
restore_previous_kprobe(struct kprobe_ctlblk
*kcb
)
256 __get_cpu_var(current_kprobe
) = kcb
->prev_kprobe
.kp
;
257 kcb
->kprobe_status
= kcb
->prev_kprobe
.status
;
258 kcb
->kprobe_saved_imask
= kcb
->prev_kprobe
.kprobe_saved_imask
;
259 memcpy(kcb
->kprobe_saved_ctl
, kcb
->prev_kprobe
.kprobe_saved_ctl
,
260 sizeof(kcb
->kprobe_saved_ctl
));
263 static void __kprobes
set_current_kprobe(struct kprobe
*p
, struct pt_regs
*regs
,
264 struct kprobe_ctlblk
*kcb
)
266 __get_cpu_var(current_kprobe
) = p
;
267 /* Save the interrupt and per flags */
268 kcb
->kprobe_saved_imask
= regs
->psw
.mask
&
269 (PSW_MASK_PER
| PSW_MASK_IO
| PSW_MASK_EXT
| PSW_MASK_MCHECK
);
270 /* Save the control regs that govern PER */
271 __ctl_store(kcb
->kprobe_saved_ctl
, 9, 11);
274 void __kprobes
arch_prepare_kretprobe(struct kretprobe_instance
*ri
,
275 struct pt_regs
*regs
)
277 ri
->ret_addr
= (kprobe_opcode_t
*) regs
->gprs
[14];
279 /* Replace the return addr with trampoline addr */
280 regs
->gprs
[14] = (unsigned long)&kretprobe_trampoline
;
283 static int __kprobes
kprobe_handler(struct pt_regs
*regs
)
287 unsigned long *addr
= (unsigned long *)
288 ((regs
->psw
.addr
& PSW_ADDR_INSN
) - 2);
289 struct kprobe_ctlblk
*kcb
;
292 * We don't want to be preempted for the entire
293 * duration of kprobe processing
296 kcb
= get_kprobe_ctlblk();
298 /* Check we're not actually recursing */
299 if (kprobe_running()) {
300 p
= get_kprobe(addr
);
302 if (kcb
->kprobe_status
== KPROBE_HIT_SS
&&
303 *p
->ainsn
.insn
== BREAKPOINT_INSTRUCTION
) {
304 regs
->psw
.mask
&= ~PSW_MASK_PER
;
305 regs
->psw
.mask
|= kcb
->kprobe_saved_imask
;
308 /* We have reentered the kprobe_handler(), since
309 * another probe was hit while within the handler.
310 * We here save the original kprobes variables and
311 * just single step on the instruction of the new probe
312 * without calling any user handlers.
314 save_previous_kprobe(kcb
);
315 set_current_kprobe(p
, regs
, kcb
);
316 kprobes_inc_nmissed_count(p
);
317 prepare_singlestep(p
, regs
);
318 kcb
->kprobe_status
= KPROBE_REENTER
;
321 p
= __get_cpu_var(current_kprobe
);
322 if (p
->break_handler
&& p
->break_handler(p
, regs
)) {
329 p
= get_kprobe(addr
);
332 * No kprobe at this address. The fault has not been
333 * caused by a kprobe breakpoint. The race of breakpoint
334 * vs. kprobe remove does not exist because on s390 we
335 * use stop_machine to arm/disarm the breakpoints.
339 kcb
->kprobe_status
= KPROBE_HIT_ACTIVE
;
340 set_current_kprobe(p
, regs
, kcb
);
341 if (p
->pre_handler
&& p
->pre_handler(p
, regs
))
342 /* handler has already set things up, so skip ss setup */
346 prepare_singlestep(p
, regs
);
347 kcb
->kprobe_status
= KPROBE_HIT_SS
;
351 preempt_enable_no_resched();
356 * Function return probe trampoline:
357 * - init_kprobes() establishes a probepoint here
358 * - When the probed function returns, this probe
359 * causes the handlers to fire
361 static void __used
kretprobe_trampoline_holder(void)
363 asm volatile(".global kretprobe_trampoline\n"
364 "kretprobe_trampoline: bcr 0,0\n");
368 * Called when the probe at kretprobe trampoline is hit
370 static int __kprobes
trampoline_probe_handler(struct kprobe
*p
,
371 struct pt_regs
*regs
)
373 struct kretprobe_instance
*ri
= NULL
;
374 struct hlist_head
*head
, empty_rp
;
375 struct hlist_node
*node
, *tmp
;
376 unsigned long flags
, orig_ret_address
= 0;
377 unsigned long trampoline_address
= (unsigned long)&kretprobe_trampoline
;
379 INIT_HLIST_HEAD(&empty_rp
);
380 kretprobe_hash_lock(current
, &head
, &flags
);
383 * It is possible to have multiple instances associated with a given
384 * task either because an multiple functions in the call path
385 * have a return probe installed on them, and/or more than one return
386 * return probe was registered for a target function.
388 * We can handle this because:
389 * - instances are always inserted at the head of the list
390 * - when multiple return probes are registered for the same
391 * function, the first instance's ret_addr will point to the
392 * real return address, and all the rest will point to
393 * kretprobe_trampoline
395 hlist_for_each_entry_safe(ri
, node
, tmp
, head
, hlist
) {
396 if (ri
->task
!= current
)
397 /* another task is sharing our hash bucket */
400 if (ri
->rp
&& ri
->rp
->handler
)
401 ri
->rp
->handler(ri
, regs
);
403 orig_ret_address
= (unsigned long)ri
->ret_addr
;
404 recycle_rp_inst(ri
, &empty_rp
);
406 if (orig_ret_address
!= trampoline_address
) {
408 * This is the real return address. Any other
409 * instances associated with this task are for
410 * other calls deeper on the call stack
415 kretprobe_assert(ri
, orig_ret_address
, trampoline_address
);
416 regs
->psw
.addr
= orig_ret_address
| PSW_ADDR_AMODE
;
418 reset_current_kprobe();
419 kretprobe_hash_unlock(current
, &flags
);
420 preempt_enable_no_resched();
422 hlist_for_each_entry_safe(ri
, node
, tmp
, &empty_rp
, hlist
) {
423 hlist_del(&ri
->hlist
);
427 * By returning a non-zero value, we are telling
428 * kprobe_handler() that we don't want the post_handler
429 * to run (and have re-enabled preemption)
435 * Called after single-stepping. p->addr is the address of the
436 * instruction whose first byte has been replaced by the "breakpoint"
437 * instruction. To avoid the SMP problems that can occur when we
438 * temporarily put back the original opcode to single-step, we
439 * single-stepped a copy of the instruction. The address of this
440 * copy is p->ainsn.insn.
442 static void __kprobes
resume_execution(struct kprobe
*p
, struct pt_regs
*regs
)
444 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
446 regs
->psw
.addr
&= PSW_ADDR_INSN
;
448 if (p
->ainsn
.fixup
& FIXUP_PSW_NORMAL
)
449 regs
->psw
.addr
= (unsigned long)p
->addr
+
450 ((unsigned long)regs
->psw
.addr
-
451 (unsigned long)p
->ainsn
.insn
);
453 if (p
->ainsn
.fixup
& FIXUP_BRANCH_NOT_TAKEN
)
454 if ((unsigned long)regs
->psw
.addr
-
455 (unsigned long)p
->ainsn
.insn
== p
->ainsn
.ilen
)
456 regs
->psw
.addr
= (unsigned long)p
->addr
+ p
->ainsn
.ilen
;
458 if (p
->ainsn
.fixup
& FIXUP_RETURN_REGISTER
)
459 regs
->gprs
[p
->ainsn
.reg
] = ((unsigned long)p
->addr
+
460 (regs
->gprs
[p
->ainsn
.reg
] -
461 (unsigned long)p
->ainsn
.insn
))
464 regs
->psw
.addr
|= PSW_ADDR_AMODE
;
465 /* turn off PER mode */
466 regs
->psw
.mask
&= ~PSW_MASK_PER
;
467 /* Restore the original per control regs */
468 __ctl_load(kcb
->kprobe_saved_ctl
, 9, 11);
469 regs
->psw
.mask
|= kcb
->kprobe_saved_imask
;
472 static int __kprobes
post_kprobe_handler(struct pt_regs
*regs
)
474 struct kprobe
*cur
= kprobe_running();
475 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
480 if ((kcb
->kprobe_status
!= KPROBE_REENTER
) && cur
->post_handler
) {
481 kcb
->kprobe_status
= KPROBE_HIT_SSDONE
;
482 cur
->post_handler(cur
, regs
, 0);
485 resume_execution(cur
, regs
);
487 /*Restore back the original saved kprobes variables and continue. */
488 if (kcb
->kprobe_status
== KPROBE_REENTER
) {
489 restore_previous_kprobe(kcb
);
492 reset_current_kprobe();
494 preempt_enable_no_resched();
497 * if somebody else is singlestepping across a probe point, psw mask
498 * will have PER set, in which case, continue the remaining processing
499 * of do_single_step, as if this is not a probe hit.
501 if (regs
->psw
.mask
& PSW_MASK_PER
) {
508 int __kprobes
kprobe_fault_handler(struct pt_regs
*regs
, int trapnr
)
510 struct kprobe
*cur
= kprobe_running();
511 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
512 const struct exception_table_entry
*entry
;
514 switch(kcb
->kprobe_status
) {
515 case KPROBE_SWAP_INST
:
516 /* We are here because the instruction replacement failed */
521 * We are here because the instruction being single
522 * stepped caused a page fault. We reset the current
523 * kprobe and the nip points back to the probe address
524 * and allow the page fault handler to continue as a
527 regs
->psw
.addr
= (unsigned long)cur
->addr
| PSW_ADDR_AMODE
;
528 regs
->psw
.mask
&= ~PSW_MASK_PER
;
529 regs
->psw
.mask
|= kcb
->kprobe_saved_imask
;
530 if (kcb
->kprobe_status
== KPROBE_REENTER
)
531 restore_previous_kprobe(kcb
);
533 reset_current_kprobe();
534 preempt_enable_no_resched();
536 case KPROBE_HIT_ACTIVE
:
537 case KPROBE_HIT_SSDONE
:
539 * We increment the nmissed count for accounting,
540 * we can also use npre/npostfault count for accouting
541 * these specific fault cases.
543 kprobes_inc_nmissed_count(cur
);
546 * We come here because instructions in the pre/post
547 * handler caused the page_fault, this could happen
548 * if handler tries to access user space by
549 * copy_from_user(), get_user() etc. Let the
550 * user-specified handler try to fix it first.
552 if (cur
->fault_handler
&& cur
->fault_handler(cur
, regs
, trapnr
))
556 * In case the user-specified fault handler returned
557 * zero, try to fix up.
559 entry
= search_exception_tables(regs
->psw
.addr
& PSW_ADDR_INSN
);
561 regs
->psw
.addr
= entry
->fixup
| PSW_ADDR_AMODE
;
566 * fixup_exception() could not handle it,
567 * Let do_page_fault() fix it.
577 * Wrapper routine to for handling exceptions.
579 int __kprobes
kprobe_exceptions_notify(struct notifier_block
*self
,
580 unsigned long val
, void *data
)
582 struct die_args
*args
= (struct die_args
*)data
;
583 int ret
= NOTIFY_DONE
;
587 if (kprobe_handler(args
->regs
))
591 if (post_kprobe_handler(args
->regs
))
595 /* kprobe_running() needs smp_processor_id() */
597 if (kprobe_running() &&
598 kprobe_fault_handler(args
->regs
, args
->trapnr
))
608 int __kprobes
setjmp_pre_handler(struct kprobe
*p
, struct pt_regs
*regs
)
610 struct jprobe
*jp
= container_of(p
, struct jprobe
, kp
);
612 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
614 memcpy(&kcb
->jprobe_saved_regs
, regs
, sizeof(struct pt_regs
));
616 /* setup return addr to the jprobe handler routine */
617 regs
->psw
.addr
= (unsigned long)(jp
->entry
) | PSW_ADDR_AMODE
;
619 /* r14 is the function return address */
620 kcb
->jprobe_saved_r14
= (unsigned long)regs
->gprs
[14];
621 /* r15 is the stack pointer */
622 kcb
->jprobe_saved_r15
= (unsigned long)regs
->gprs
[15];
623 addr
= (unsigned long)kcb
->jprobe_saved_r15
;
625 memcpy(kcb
->jprobes_stack
, (kprobe_opcode_t
*) addr
,
626 MIN_STACK_SIZE(addr
));
630 void __kprobes
jprobe_return(void)
632 asm volatile(".word 0x0002");
635 void __kprobes
jprobe_return_end(void)
637 asm volatile("bcr 0,0");
640 int __kprobes
longjmp_break_handler(struct kprobe
*p
, struct pt_regs
*regs
)
642 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
643 unsigned long stack_addr
= (unsigned long)(kcb
->jprobe_saved_r15
);
645 /* Put the regs back */
646 memcpy(regs
, &kcb
->jprobe_saved_regs
, sizeof(struct pt_regs
));
647 /* put the stack back */
648 memcpy((kprobe_opcode_t
*) stack_addr
, kcb
->jprobes_stack
,
649 MIN_STACK_SIZE(stack_addr
));
650 preempt_enable_no_resched();
654 static struct kprobe trampoline_p
= {
655 .addr
= (kprobe_opcode_t
*) & kretprobe_trampoline
,
656 .pre_handler
= trampoline_probe_handler
659 int __init
arch_init_kprobes(void)
661 return register_kprobe(&trampoline_p
);
664 int __kprobes
arch_trampoline_kprobe(struct kprobe
*p
)
666 if (p
->addr
== (kprobe_opcode_t
*) & kretprobe_trampoline
)