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 int __kprobes
arch_prepare_kprobe(struct kprobe
*p
)
38 /* Make sure the probe isn't going on a difficult instruction */
39 if (is_prohibited_opcode((kprobe_opcode_t
*) p
->addr
))
42 if ((unsigned long)p
->addr
& 0x01) {
43 printk("Attempt to register kprobe at an unaligned address\n");
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
) >> 4) {
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_run(swap_instruction
, &args
, NR_CPUS
);
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_run(swap_instruction
, &args
, NR_CPUS
);
216 kcb
->kprobe_status
= status
;
219 void __kprobes
arch_remove_kprobe(struct kprobe
*p
)
221 mutex_lock(&kprobe_mutex
);
222 free_insn_slot(p
->ainsn
.insn
, 0);
223 mutex_unlock(&kprobe_mutex
);
226 static void __kprobes
prepare_singlestep(struct kprobe
*p
, struct pt_regs
*regs
)
228 per_cr_bits kprobe_per_regs
[1];
230 memset(kprobe_per_regs
, 0, sizeof(per_cr_bits
));
231 regs
->psw
.addr
= (unsigned long)p
->ainsn
.insn
| PSW_ADDR_AMODE
;
233 /* Set up the per control reg info, will pass to lctl */
234 kprobe_per_regs
[0].em_instruction_fetch
= 1;
235 kprobe_per_regs
[0].starting_addr
= (unsigned long)p
->ainsn
.insn
;
236 kprobe_per_regs
[0].ending_addr
= (unsigned long)p
->ainsn
.insn
+ 1;
238 /* Set the PER control regs, turns on single step for this address */
239 __ctl_load(kprobe_per_regs
, 9, 11);
240 regs
->psw
.mask
|= PSW_MASK_PER
;
241 regs
->psw
.mask
&= ~(PSW_MASK_IO
| PSW_MASK_EXT
| PSW_MASK_MCHECK
);
244 static void __kprobes
save_previous_kprobe(struct kprobe_ctlblk
*kcb
)
246 kcb
->prev_kprobe
.kp
= kprobe_running();
247 kcb
->prev_kprobe
.status
= kcb
->kprobe_status
;
248 kcb
->prev_kprobe
.kprobe_saved_imask
= kcb
->kprobe_saved_imask
;
249 memcpy(kcb
->prev_kprobe
.kprobe_saved_ctl
, kcb
->kprobe_saved_ctl
,
250 sizeof(kcb
->kprobe_saved_ctl
));
253 static void __kprobes
restore_previous_kprobe(struct kprobe_ctlblk
*kcb
)
255 __get_cpu_var(current_kprobe
) = kcb
->prev_kprobe
.kp
;
256 kcb
->kprobe_status
= kcb
->prev_kprobe
.status
;
257 kcb
->kprobe_saved_imask
= kcb
->prev_kprobe
.kprobe_saved_imask
;
258 memcpy(kcb
->kprobe_saved_ctl
, kcb
->prev_kprobe
.kprobe_saved_ctl
,
259 sizeof(kcb
->kprobe_saved_ctl
));
262 static void __kprobes
set_current_kprobe(struct kprobe
*p
, struct pt_regs
*regs
,
263 struct kprobe_ctlblk
*kcb
)
265 __get_cpu_var(current_kprobe
) = p
;
266 /* Save the interrupt and per flags */
267 kcb
->kprobe_saved_imask
= regs
->psw
.mask
&
268 (PSW_MASK_PER
| PSW_MASK_IO
| PSW_MASK_EXT
| PSW_MASK_MCHECK
);
269 /* Save the control regs that govern PER */
270 __ctl_store(kcb
->kprobe_saved_ctl
, 9, 11);
273 /* Called with kretprobe_lock held */
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_run 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 void 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 spin_lock_irqsave(&kretprobe_lock
, flags
);
381 head
= kretprobe_inst_table_head(current
);
384 * It is possible to have multiple instances associated with a given
385 * task either because an multiple functions in the call path
386 * have a return probe installed on them, and/or more then one return
387 * return probe was registered for a target function.
389 * We can handle this because:
390 * - instances are always inserted at the head of the list
391 * - when multiple return probes are registered for the same
392 * function, the first instance's ret_addr will point to the
393 * real return address, and all the rest will point to
394 * kretprobe_trampoline
396 hlist_for_each_entry_safe(ri
, node
, tmp
, head
, hlist
) {
397 if (ri
->task
!= current
)
398 /* another task is sharing our hash bucket */
401 if (ri
->rp
&& ri
->rp
->handler
)
402 ri
->rp
->handler(ri
, regs
);
404 orig_ret_address
= (unsigned long)ri
->ret_addr
;
405 recycle_rp_inst(ri
, &empty_rp
);
407 if (orig_ret_address
!= trampoline_address
) {
409 * This is the real return address. Any other
410 * instances associated with this task are for
411 * other calls deeper on the call stack
416 BUG_ON(!orig_ret_address
|| (orig_ret_address
== trampoline_address
));
417 regs
->psw
.addr
= orig_ret_address
| PSW_ADDR_AMODE
;
419 reset_current_kprobe();
420 spin_unlock_irqrestore(&kretprobe_lock
, flags
);
421 preempt_enable_no_resched();
423 hlist_for_each_entry_safe(ri
, node
, tmp
, &empty_rp
, hlist
) {
424 hlist_del(&ri
->hlist
);
428 * By returning a non-zero value, we are telling
429 * kprobe_handler() that we don't want the post_handler
430 * to run (and have re-enabled preemption)
436 * Called after single-stepping. p->addr is the address of the
437 * instruction whose first byte has been replaced by the "breakpoint"
438 * instruction. To avoid the SMP problems that can occur when we
439 * temporarily put back the original opcode to single-step, we
440 * single-stepped a copy of the instruction. The address of this
441 * copy is p->ainsn.insn.
443 static void __kprobes
resume_execution(struct kprobe
*p
, struct pt_regs
*regs
)
445 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
447 regs
->psw
.addr
&= PSW_ADDR_INSN
;
449 if (p
->ainsn
.fixup
& FIXUP_PSW_NORMAL
)
450 regs
->psw
.addr
= (unsigned long)p
->addr
+
451 ((unsigned long)regs
->psw
.addr
-
452 (unsigned long)p
->ainsn
.insn
);
454 if (p
->ainsn
.fixup
& FIXUP_BRANCH_NOT_TAKEN
)
455 if ((unsigned long)regs
->psw
.addr
-
456 (unsigned long)p
->ainsn
.insn
== p
->ainsn
.ilen
)
457 regs
->psw
.addr
= (unsigned long)p
->addr
+ p
->ainsn
.ilen
;
459 if (p
->ainsn
.fixup
& FIXUP_RETURN_REGISTER
)
460 regs
->gprs
[p
->ainsn
.reg
] = ((unsigned long)p
->addr
+
461 (regs
->gprs
[p
->ainsn
.reg
] -
462 (unsigned long)p
->ainsn
.insn
))
465 regs
->psw
.addr
|= PSW_ADDR_AMODE
;
466 /* turn off PER mode */
467 regs
->psw
.mask
&= ~PSW_MASK_PER
;
468 /* Restore the original per control regs */
469 __ctl_load(kcb
->kprobe_saved_ctl
, 9, 11);
470 regs
->psw
.mask
|= kcb
->kprobe_saved_imask
;
473 static int __kprobes
post_kprobe_handler(struct pt_regs
*regs
)
475 struct kprobe
*cur
= kprobe_running();
476 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
481 if ((kcb
->kprobe_status
!= KPROBE_REENTER
) && cur
->post_handler
) {
482 kcb
->kprobe_status
= KPROBE_HIT_SSDONE
;
483 cur
->post_handler(cur
, regs
, 0);
486 resume_execution(cur
, regs
);
488 /*Restore back the original saved kprobes variables and continue. */
489 if (kcb
->kprobe_status
== KPROBE_REENTER
) {
490 restore_previous_kprobe(kcb
);
493 reset_current_kprobe();
495 preempt_enable_no_resched();
498 * if somebody else is singlestepping across a probe point, psw mask
499 * will have PER set, in which case, continue the remaining processing
500 * of do_single_step, as if this is not a probe hit.
502 if (regs
->psw
.mask
& PSW_MASK_PER
) {
509 int __kprobes
kprobe_fault_handler(struct pt_regs
*regs
, int trapnr
)
511 struct kprobe
*cur
= kprobe_running();
512 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
513 const struct exception_table_entry
*entry
;
515 switch(kcb
->kprobe_status
) {
516 case KPROBE_SWAP_INST
:
517 /* We are here because the instruction replacement failed */
522 * We are here because the instruction being single
523 * stepped caused a page fault. We reset the current
524 * kprobe and the nip points back to the probe address
525 * and allow the page fault handler to continue as a
528 regs
->psw
.addr
= (unsigned long)cur
->addr
| PSW_ADDR_AMODE
;
529 regs
->psw
.mask
&= ~PSW_MASK_PER
;
530 regs
->psw
.mask
|= kcb
->kprobe_saved_imask
;
531 if (kcb
->kprobe_status
== KPROBE_REENTER
)
532 restore_previous_kprobe(kcb
);
534 reset_current_kprobe();
535 preempt_enable_no_resched();
537 case KPROBE_HIT_ACTIVE
:
538 case KPROBE_HIT_SSDONE
:
540 * We increment the nmissed count for accounting,
541 * we can also use npre/npostfault count for accouting
542 * these specific fault cases.
544 kprobes_inc_nmissed_count(cur
);
547 * We come here because instructions in the pre/post
548 * handler caused the page_fault, this could happen
549 * if handler tries to access user space by
550 * copy_from_user(), get_user() etc. Let the
551 * user-specified handler try to fix it first.
553 if (cur
->fault_handler
&& cur
->fault_handler(cur
, regs
, trapnr
))
557 * In case the user-specified fault handler returned
558 * zero, try to fix up.
560 entry
= search_exception_tables(regs
->psw
.addr
& PSW_ADDR_INSN
);
562 regs
->psw
.addr
= entry
->fixup
| PSW_ADDR_AMODE
;
567 * fixup_exception() could not handle it,
568 * Let do_page_fault() fix it.
578 * Wrapper routine to for handling exceptions.
580 int __kprobes
kprobe_exceptions_notify(struct notifier_block
*self
,
581 unsigned long val
, void *data
)
583 struct die_args
*args
= (struct die_args
*)data
;
584 int ret
= NOTIFY_DONE
;
588 if (kprobe_handler(args
->regs
))
592 if (post_kprobe_handler(args
->regs
))
596 /* kprobe_running() needs smp_processor_id() */
598 if (kprobe_running() &&
599 kprobe_fault_handler(args
->regs
, args
->trapnr
))
609 int __kprobes
setjmp_pre_handler(struct kprobe
*p
, struct pt_regs
*regs
)
611 struct jprobe
*jp
= container_of(p
, struct jprobe
, kp
);
613 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
615 memcpy(&kcb
->jprobe_saved_regs
, regs
, sizeof(struct pt_regs
));
617 /* setup return addr to the jprobe handler routine */
618 regs
->psw
.addr
= (unsigned long)(jp
->entry
) | PSW_ADDR_AMODE
;
620 /* r14 is the function return address */
621 kcb
->jprobe_saved_r14
= (unsigned long)regs
->gprs
[14];
622 /* r15 is the stack pointer */
623 kcb
->jprobe_saved_r15
= (unsigned long)regs
->gprs
[15];
624 addr
= (unsigned long)kcb
->jprobe_saved_r15
;
626 memcpy(kcb
->jprobes_stack
, (kprobe_opcode_t
*) addr
,
627 MIN_STACK_SIZE(addr
));
631 void __kprobes
jprobe_return(void)
633 asm volatile(".word 0x0002");
636 void __kprobes
jprobe_return_end(void)
638 asm volatile("bcr 0,0");
641 int __kprobes
longjmp_break_handler(struct kprobe
*p
, struct pt_regs
*regs
)
643 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
644 unsigned long stack_addr
= (unsigned long)(kcb
->jprobe_saved_r15
);
646 /* Put the regs back */
647 memcpy(regs
, &kcb
->jprobe_saved_regs
, sizeof(struct pt_regs
));
648 /* put the stack back */
649 memcpy((kprobe_opcode_t
*) stack_addr
, kcb
->jprobes_stack
,
650 MIN_STACK_SIZE(stack_addr
));
651 preempt_enable_no_resched();
655 static struct kprobe trampoline_p
= {
656 .addr
= (kprobe_opcode_t
*) & kretprobe_trampoline
,
657 .pre_handler
= trampoline_probe_handler
660 int __init
arch_init_kprobes(void)
662 return register_kprobe(&trampoline_p
);
665 int __kprobes
arch_trampoline_kprobe(struct kprobe
*p
)
667 if (p
->addr
== (kprobe_opcode_t
*) & kretprobe_trampoline
)