2 * Kernel Probes (KProbes)
3 * arch/x86_64/kernel/kprobes.c
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
19 * Copyright (C) IBM Corporation, 2002, 2004
21 * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
22 * Probes initial implementation ( includes contributions from
24 * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
25 * interface to access function arguments.
26 * 2004-Oct Jim Keniston <kenistoj@us.ibm.com> and Prasanna S Panchamukhi
27 * <prasanna@in.ibm.com> adapted for x86_64
28 * 2005-Mar Roland McGrath <roland@redhat.com>
29 * Fixed to handle %rip-relative addressing mode correctly.
30 * 2005-May Rusty Lynch <rusty.lynch@intel.com>
31 * Added function return probes functionality
34 #include <linux/config.h>
35 #include <linux/kprobes.h>
36 #include <linux/ptrace.h>
37 #include <linux/string.h>
38 #include <linux/slab.h>
39 #include <linux/preempt.h>
40 #include <linux/module.h>
42 #include <asm/cacheflush.h>
43 #include <asm/pgtable.h>
44 #include <asm/kdebug.h>
45 #include <asm/uaccess.h>
47 void jprobe_return_end(void);
48 static void __kprobes
arch_copy_kprobe(struct kprobe
*p
);
50 DEFINE_PER_CPU(struct kprobe
*, current_kprobe
) = NULL
;
51 DEFINE_PER_CPU(struct kprobe_ctlblk
, kprobe_ctlblk
);
54 * returns non-zero if opcode modifies the interrupt flag.
56 static __always_inline
int is_IF_modifier(kprobe_opcode_t
*insn
)
61 case 0xcf: /* iret/iretd */
62 case 0x9d: /* popf/popfd */
66 if (*insn
>= 0x40 && *insn
<= 0x4f && *++insn
== 0xcf)
71 int __kprobes
arch_prepare_kprobe(struct kprobe
*p
)
73 /* insn: must be on special executable page on x86_64. */
74 p
->ainsn
.insn
= get_insn_slot();
83 * Determine if the instruction uses the %rip-relative addressing mode.
84 * If it does, return the address of the 32-bit displacement word.
85 * If not, return null.
87 static s32 __kprobes
*is_riprel(u8
*insn
)
89 #define W(row,b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,ba,bb,bc,bd,be,bf) \
90 (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \
91 (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \
92 (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \
93 (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \
95 static const u64 onebyte_has_modrm
[256 / 64] = {
96 /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
97 /* ------------------------------- */
98 W(0x00, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 00 */
99 W(0x10, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 10 */
100 W(0x20, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 20 */
101 W(0x30, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0), /* 30 */
102 W(0x40, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 40 */
103 W(0x50, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 50 */
104 W(0x60, 0,0,1,1,0,0,0,0,0,1,0,1,0,0,0,0)| /* 60 */
105 W(0x70, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 70 */
106 W(0x80, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 80 */
107 W(0x90, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 90 */
108 W(0xa0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* a0 */
109 W(0xb0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* b0 */
110 W(0xc0, 1,1,0,0,1,1,1,1,0,0,0,0,0,0,0,0)| /* c0 */
111 W(0xd0, 1,1,1,1,0,0,0,0,1,1,1,1,1,1,1,1)| /* d0 */
112 W(0xe0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* e0 */
113 W(0xf0, 0,0,0,0,0,0,1,1,0,0,0,0,0,0,1,1) /* f0 */
114 /* ------------------------------- */
115 /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
117 static const u64 twobyte_has_modrm
[256 / 64] = {
118 /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
119 /* ------------------------------- */
120 W(0x00, 1,1,1,1,0,0,0,0,0,0,0,0,0,1,0,1)| /* 0f */
121 W(0x10, 1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0)| /* 1f */
122 W(0x20, 1,1,1,1,1,0,1,0,1,1,1,1,1,1,1,1)| /* 2f */
123 W(0x30, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 3f */
124 W(0x40, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 4f */
125 W(0x50, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 5f */
126 W(0x60, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 6f */
127 W(0x70, 1,1,1,1,1,1,1,0,0,0,0,0,1,1,1,1), /* 7f */
128 W(0x80, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 8f */
129 W(0x90, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 9f */
130 W(0xa0, 0,0,0,1,1,1,1,1,0,0,0,1,1,1,1,1)| /* af */
131 W(0xb0, 1,1,1,1,1,1,1,1,0,0,1,1,1,1,1,1), /* bf */
132 W(0xc0, 1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0)| /* cf */
133 W(0xd0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* df */
134 W(0xe0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* ef */
135 W(0xf0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0) /* ff */
136 /* ------------------------------- */
137 /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
142 /* Skip legacy instruction prefixes. */
162 /* Skip REX instruction prefix. */
163 if ((*insn
& 0xf0) == 0x40)
166 if (*insn
== 0x0f) { /* Two-byte opcode. */
168 need_modrm
= test_bit(*insn
, twobyte_has_modrm
);
169 } else { /* One-byte opcode. */
170 need_modrm
= test_bit(*insn
, onebyte_has_modrm
);
175 if ((modrm
& 0xc7) == 0x05) { /* %rip+disp32 addressing mode */
176 /* Displacement follows ModRM byte. */
177 return (s32
*) ++insn
;
181 /* No %rip-relative addressing mode here. */
185 static void __kprobes
arch_copy_kprobe(struct kprobe
*p
)
188 memcpy(p
->ainsn
.insn
, p
->addr
, MAX_INSN_SIZE
);
189 ripdisp
= is_riprel(p
->ainsn
.insn
);
192 * The copied instruction uses the %rip-relative
193 * addressing mode. Adjust the displacement for the
194 * difference between the original location of this
195 * instruction and the location of the copy that will
196 * actually be run. The tricky bit here is making sure
197 * that the sign extension happens correctly in this
198 * calculation, since we need a signed 32-bit result to
199 * be sign-extended to 64 bits when it's added to the
200 * %rip value and yield the same 64-bit result that the
201 * sign-extension of the original signed 32-bit
202 * displacement would have given.
204 s64 disp
= (u8
*) p
->addr
+ *ripdisp
- (u8
*) p
->ainsn
.insn
;
205 BUG_ON((s64
) (s32
) disp
!= disp
); /* Sanity check. */
208 p
->opcode
= *p
->addr
;
211 void __kprobes
arch_arm_kprobe(struct kprobe
*p
)
213 *p
->addr
= BREAKPOINT_INSTRUCTION
;
214 flush_icache_range((unsigned long) p
->addr
,
215 (unsigned long) p
->addr
+ sizeof(kprobe_opcode_t
));
218 void __kprobes
arch_disarm_kprobe(struct kprobe
*p
)
220 *p
->addr
= p
->opcode
;
221 flush_icache_range((unsigned long) p
->addr
,
222 (unsigned long) p
->addr
+ sizeof(kprobe_opcode_t
));
225 void __kprobes
arch_remove_kprobe(struct kprobe
*p
)
227 mutex_lock(&kprobe_mutex
);
228 free_insn_slot(p
->ainsn
.insn
);
229 mutex_unlock(&kprobe_mutex
);
232 static void __kprobes
save_previous_kprobe(struct kprobe_ctlblk
*kcb
)
234 kcb
->prev_kprobe
.kp
= kprobe_running();
235 kcb
->prev_kprobe
.status
= kcb
->kprobe_status
;
236 kcb
->prev_kprobe
.old_rflags
= kcb
->kprobe_old_rflags
;
237 kcb
->prev_kprobe
.saved_rflags
= kcb
->kprobe_saved_rflags
;
240 static void __kprobes
restore_previous_kprobe(struct kprobe_ctlblk
*kcb
)
242 __get_cpu_var(current_kprobe
) = kcb
->prev_kprobe
.kp
;
243 kcb
->kprobe_status
= kcb
->prev_kprobe
.status
;
244 kcb
->kprobe_old_rflags
= kcb
->prev_kprobe
.old_rflags
;
245 kcb
->kprobe_saved_rflags
= kcb
->prev_kprobe
.saved_rflags
;
248 static void __kprobes
set_current_kprobe(struct kprobe
*p
, struct pt_regs
*regs
,
249 struct kprobe_ctlblk
*kcb
)
251 __get_cpu_var(current_kprobe
) = p
;
252 kcb
->kprobe_saved_rflags
= kcb
->kprobe_old_rflags
253 = (regs
->eflags
& (TF_MASK
| IF_MASK
));
254 if (is_IF_modifier(p
->ainsn
.insn
))
255 kcb
->kprobe_saved_rflags
&= ~IF_MASK
;
258 static void __kprobes
prepare_singlestep(struct kprobe
*p
, struct pt_regs
*regs
)
260 regs
->eflags
|= TF_MASK
;
261 regs
->eflags
&= ~IF_MASK
;
262 /*single step inline if the instruction is an int3*/
263 if (p
->opcode
== BREAKPOINT_INSTRUCTION
)
264 regs
->rip
= (unsigned long)p
->addr
;
266 regs
->rip
= (unsigned long)p
->ainsn
.insn
;
269 /* Called with kretprobe_lock held */
270 void __kprobes
arch_prepare_kretprobe(struct kretprobe
*rp
,
271 struct pt_regs
*regs
)
273 unsigned long *sara
= (unsigned long *)regs
->rsp
;
274 struct kretprobe_instance
*ri
;
276 if ((ri
= get_free_rp_inst(rp
)) != NULL
) {
279 ri
->ret_addr
= (kprobe_opcode_t
*) *sara
;
281 /* Replace the return addr with trampoline addr */
282 *sara
= (unsigned long) &kretprobe_trampoline
;
290 int __kprobes
kprobe_handler(struct pt_regs
*regs
)
294 kprobe_opcode_t
*addr
= (kprobe_opcode_t
*)(regs
->rip
- sizeof(kprobe_opcode_t
));
295 struct kprobe_ctlblk
*kcb
;
298 * We don't want to be preempted for the entire
299 * duration of kprobe processing
302 kcb
= get_kprobe_ctlblk();
304 /* Check we're not actually recursing */
305 if (kprobe_running()) {
306 p
= get_kprobe(addr
);
308 if (kcb
->kprobe_status
== KPROBE_HIT_SS
&&
309 *p
->ainsn
.insn
== BREAKPOINT_INSTRUCTION
) {
310 regs
->eflags
&= ~TF_MASK
;
311 regs
->eflags
|= kcb
->kprobe_saved_rflags
;
313 } else if (kcb
->kprobe_status
== KPROBE_HIT_SSDONE
) {
314 /* TODO: Provide re-entrancy from
315 * post_kprobes_handler() and avoid exception
316 * stack corruption while single-stepping on
317 * the instruction of the new probe.
319 arch_disarm_kprobe(p
);
320 regs
->rip
= (unsigned long)p
->addr
;
321 reset_current_kprobe();
324 /* We have reentered the kprobe_handler(), since
325 * another probe was hit while within the
326 * handler. We here save the original kprobe
327 * variables and just single step on instruction
328 * of the new probe without calling any user
331 save_previous_kprobe(kcb
);
332 set_current_kprobe(p
, regs
, kcb
);
333 kprobes_inc_nmissed_count(p
);
334 prepare_singlestep(p
, regs
);
335 kcb
->kprobe_status
= KPROBE_REENTER
;
339 if (*addr
!= BREAKPOINT_INSTRUCTION
) {
340 /* The breakpoint instruction was removed by
341 * another cpu right after we hit, no further
342 * handling of this interrupt is appropriate
344 regs
->rip
= (unsigned long)addr
;
348 p
= __get_cpu_var(current_kprobe
);
349 if (p
->break_handler
&& p
->break_handler(p
, regs
)) {
356 p
= get_kprobe(addr
);
358 if (*addr
!= BREAKPOINT_INSTRUCTION
) {
360 * The breakpoint instruction was removed right
361 * after we hit it. Another cpu has removed
362 * either a probepoint or a debugger breakpoint
363 * at this address. In either case, no further
364 * handling of this interrupt is appropriate.
365 * Back up over the (now missing) int3 and run
366 * the original instruction.
368 regs
->rip
= (unsigned long)addr
;
371 /* Not one of ours: let kernel handle it */
375 set_current_kprobe(p
, regs
, kcb
);
376 kcb
->kprobe_status
= KPROBE_HIT_ACTIVE
;
378 if (p
->pre_handler
&& p
->pre_handler(p
, regs
))
379 /* handler has already set things up, so skip ss setup */
383 prepare_singlestep(p
, regs
);
384 kcb
->kprobe_status
= KPROBE_HIT_SS
;
388 preempt_enable_no_resched();
393 * For function-return probes, init_kprobes() establishes a probepoint
394 * here. When a retprobed function returns, this probe is hit and
395 * trampoline_probe_handler() runs, calling the kretprobe's handler.
397 void kretprobe_trampoline_holder(void)
399 asm volatile ( ".global kretprobe_trampoline\n"
400 "kretprobe_trampoline: \n"
405 * Called when we hit the probe point at kretprobe_trampoline
407 int __kprobes
trampoline_probe_handler(struct kprobe
*p
, struct pt_regs
*regs
)
409 struct kretprobe_instance
*ri
= NULL
;
410 struct hlist_head
*head
;
411 struct hlist_node
*node
, *tmp
;
412 unsigned long flags
, orig_ret_address
= 0;
413 unsigned long trampoline_address
=(unsigned long)&kretprobe_trampoline
;
415 spin_lock_irqsave(&kretprobe_lock
, flags
);
416 head
= kretprobe_inst_table_head(current
);
419 * It is possible to have multiple instances associated with a given
420 * task either because an multiple functions in the call path
421 * have a return probe installed on them, and/or more then one return
422 * return probe was registered for a target function.
424 * We can handle this because:
425 * - instances are always inserted at the head of the list
426 * - when multiple return probes are registered for the same
427 * function, the first instance's ret_addr will point to the
428 * real return address, and all the rest will point to
429 * kretprobe_trampoline
431 hlist_for_each_entry_safe(ri
, node
, tmp
, head
, hlist
) {
432 if (ri
->task
!= current
)
433 /* another task is sharing our hash bucket */
436 if (ri
->rp
&& ri
->rp
->handler
)
437 ri
->rp
->handler(ri
, regs
);
439 orig_ret_address
= (unsigned long)ri
->ret_addr
;
442 if (orig_ret_address
!= trampoline_address
)
444 * This is the real return address. Any other
445 * instances associated with this task are for
446 * other calls deeper on the call stack
451 BUG_ON(!orig_ret_address
|| (orig_ret_address
== trampoline_address
));
452 regs
->rip
= orig_ret_address
;
454 reset_current_kprobe();
455 spin_unlock_irqrestore(&kretprobe_lock
, flags
);
456 preempt_enable_no_resched();
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)
467 * Called after single-stepping. p->addr is the address of the
468 * instruction whose first byte has been replaced by the "int 3"
469 * instruction. To avoid the SMP problems that can occur when we
470 * temporarily put back the original opcode to single-step, we
471 * single-stepped a copy of the instruction. The address of this
472 * copy is p->ainsn.insn.
474 * This function prepares to return from the post-single-step
475 * interrupt. We have to fix up the stack as follows:
477 * 0) Except in the case of absolute or indirect jump or call instructions,
478 * the new rip is relative to the copied instruction. We need to make
479 * it relative to the original instruction.
481 * 1) If the single-stepped instruction was pushfl, then the TF and IF
482 * flags are set in the just-pushed eflags, and may need to be cleared.
484 * 2) If the single-stepped instruction was a call, the return address
485 * that is atop the stack is the address following the copied instruction.
486 * We need to make it the address following the original instruction.
488 static void __kprobes
resume_execution(struct kprobe
*p
,
489 struct pt_regs
*regs
, struct kprobe_ctlblk
*kcb
)
491 unsigned long *tos
= (unsigned long *)regs
->rsp
;
492 unsigned long next_rip
= 0;
493 unsigned long copy_rip
= (unsigned long)p
->ainsn
.insn
;
494 unsigned long orig_rip
= (unsigned long)p
->addr
;
495 kprobe_opcode_t
*insn
= p
->ainsn
.insn
;
497 /*skip the REX prefix*/
498 if (*insn
>= 0x40 && *insn
<= 0x4f)
502 case 0x9c: /* pushfl */
503 *tos
&= ~(TF_MASK
| IF_MASK
);
504 *tos
|= kcb
->kprobe_old_rflags
;
506 case 0xc3: /* ret/lret */
510 regs
->eflags
&= ~TF_MASK
;
511 /* rip is already adjusted, no more changes required*/
513 case 0xe8: /* call relative - Fix return addr */
514 *tos
= orig_rip
+ (*tos
- copy_rip
);
517 if ((*insn
& 0x30) == 0x10) {
518 /* call absolute, indirect */
519 /* Fix return addr; rip is correct. */
520 next_rip
= regs
->rip
;
521 *tos
= orig_rip
+ (*tos
- copy_rip
);
522 } else if (((*insn
& 0x31) == 0x20) || /* jmp near, absolute indirect */
523 ((*insn
& 0x31) == 0x21)) { /* jmp far, absolute indirect */
524 /* rip is correct. */
525 next_rip
= regs
->rip
;
528 case 0xea: /* jmp absolute -- rip is correct */
529 next_rip
= regs
->rip
;
535 regs
->eflags
&= ~TF_MASK
;
537 regs
->rip
= next_rip
;
539 regs
->rip
= orig_rip
+ (regs
->rip
- copy_rip
);
543 int __kprobes
post_kprobe_handler(struct pt_regs
*regs
)
545 struct kprobe
*cur
= kprobe_running();
546 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
551 if ((kcb
->kprobe_status
!= KPROBE_REENTER
) && cur
->post_handler
) {
552 kcb
->kprobe_status
= KPROBE_HIT_SSDONE
;
553 cur
->post_handler(cur
, regs
, 0);
556 resume_execution(cur
, regs
, kcb
);
557 regs
->eflags
|= kcb
->kprobe_saved_rflags
;
559 /* Restore the original saved kprobes variables and continue. */
560 if (kcb
->kprobe_status
== KPROBE_REENTER
) {
561 restore_previous_kprobe(kcb
);
564 reset_current_kprobe();
566 preempt_enable_no_resched();
569 * if somebody else is singlestepping across a probe point, eflags
570 * will have TF set, in which case, continue the remaining processing
571 * of do_debug, as if this is not a probe hit.
573 if (regs
->eflags
& TF_MASK
)
579 int __kprobes
kprobe_fault_handler(struct pt_regs
*regs
, int trapnr
)
581 struct kprobe
*cur
= kprobe_running();
582 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
583 const struct exception_table_entry
*fixup
;
585 switch(kcb
->kprobe_status
) {
589 * We are here because the instruction being single
590 * stepped caused a page fault. We reset the current
591 * kprobe and the rip points back to the probe address
592 * and allow the page fault handler to continue as a
595 regs
->rip
= (unsigned long)cur
->addr
;
596 regs
->eflags
|= kcb
->kprobe_old_rflags
;
597 if (kcb
->kprobe_status
== KPROBE_REENTER
)
598 restore_previous_kprobe(kcb
);
600 reset_current_kprobe();
601 preempt_enable_no_resched();
603 case KPROBE_HIT_ACTIVE
:
604 case KPROBE_HIT_SSDONE
:
606 * We increment the nmissed count for accounting,
607 * we can also use npre/npostfault count for accouting
608 * these specific fault cases.
610 kprobes_inc_nmissed_count(cur
);
613 * We come here because instructions in the pre/post
614 * handler caused the page_fault, this could happen
615 * if handler tries to access user space by
616 * copy_from_user(), get_user() etc. Let the
617 * user-specified handler try to fix it first.
619 if (cur
->fault_handler
&& cur
->fault_handler(cur
, regs
, trapnr
))
623 * In case the user-specified fault handler returned
624 * zero, try to fix up.
626 fixup
= search_exception_tables(regs
->rip
);
628 regs
->rip
= fixup
->fixup
;
633 * fixup() could not handle it,
634 * Let do_page_fault() fix it.
644 * Wrapper routine for handling exceptions.
646 int __kprobes
kprobe_exceptions_notify(struct notifier_block
*self
,
647 unsigned long val
, void *data
)
649 struct die_args
*args
= (struct die_args
*)data
;
650 int ret
= NOTIFY_DONE
;
652 if (args
->regs
&& user_mode(args
->regs
))
657 if (kprobe_handler(args
->regs
))
661 if (post_kprobe_handler(args
->regs
))
666 /* kprobe_running() needs smp_processor_id() */
668 if (kprobe_running() &&
669 kprobe_fault_handler(args
->regs
, args
->trapnr
))
679 int __kprobes
setjmp_pre_handler(struct kprobe
*p
, struct pt_regs
*regs
)
681 struct jprobe
*jp
= container_of(p
, struct jprobe
, kp
);
683 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
685 kcb
->jprobe_saved_regs
= *regs
;
686 kcb
->jprobe_saved_rsp
= (long *) regs
->rsp
;
687 addr
= (unsigned long)(kcb
->jprobe_saved_rsp
);
689 * As Linus pointed out, gcc assumes that the callee
690 * owns the argument space and could overwrite it, e.g.
691 * tailcall optimization. So, to be absolutely safe
692 * we also save and restore enough stack bytes to cover
695 memcpy(kcb
->jprobes_stack
, (kprobe_opcode_t
*)addr
,
696 MIN_STACK_SIZE(addr
));
697 regs
->eflags
&= ~IF_MASK
;
698 regs
->rip
= (unsigned long)(jp
->entry
);
702 void __kprobes
jprobe_return(void)
704 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
706 asm volatile (" xchg %%rbx,%%rsp \n"
708 " .globl jprobe_return_end \n"
709 " jprobe_return_end: \n"
711 (kcb
->jprobe_saved_rsp
):"memory");
714 int __kprobes
longjmp_break_handler(struct kprobe
*p
, struct pt_regs
*regs
)
716 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
717 u8
*addr
= (u8
*) (regs
->rip
- 1);
718 unsigned long stack_addr
= (unsigned long)(kcb
->jprobe_saved_rsp
);
719 struct jprobe
*jp
= container_of(p
, struct jprobe
, kp
);
721 if ((addr
> (u8
*) jprobe_return
) && (addr
< (u8
*) jprobe_return_end
)) {
722 if ((long *)regs
->rsp
!= kcb
->jprobe_saved_rsp
) {
723 struct pt_regs
*saved_regs
=
724 container_of(kcb
->jprobe_saved_rsp
,
725 struct pt_regs
, rsp
);
726 printk("current rsp %p does not match saved rsp %p\n",
727 (long *)regs
->rsp
, kcb
->jprobe_saved_rsp
);
728 printk("Saved registers for jprobe %p\n", jp
);
729 show_registers(saved_regs
);
730 printk("Current registers\n");
731 show_registers(regs
);
734 *regs
= kcb
->jprobe_saved_regs
;
735 memcpy((kprobe_opcode_t
*) stack_addr
, kcb
->jprobes_stack
,
736 MIN_STACK_SIZE(stack_addr
));
737 preempt_enable_no_resched();
743 static struct kprobe trampoline_p
= {
744 .addr
= (kprobe_opcode_t
*) &kretprobe_trampoline
,
745 .pre_handler
= trampoline_probe_handler
748 int __init
arch_init_kprobes(void)
750 return register_kprobe(&trampoline_p
);