Root/arch/s390/kernel/kprobes.c

1/*
2 * Kernel Probes (KProbes)
3 *
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.
8 *
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.
13 *
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.
17 *
18 * Copyright (C) IBM Corporation, 2002, 2006
19 *
20 * s390 port, used ppc64 as template. Mike Grundy <grundym@us.ibm.com>
21 */
22
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>
33#include <linux/hardirq.h>
34
35DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
36DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
37
38struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
39
40int __kprobes arch_prepare_kprobe(struct kprobe *p)
41{
42    /* Make sure the probe isn't going on a difficult instruction */
43    if (is_prohibited_opcode((kprobe_opcode_t *) p->addr))
44        return -EINVAL;
45
46    if ((unsigned long)p->addr & 0x01)
47        return -EINVAL;
48
49    /* Use the get_insn_slot() facility for correctness */
50    if (!(p->ainsn.insn = get_insn_slot()))
51        return -ENOMEM;
52
53    memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
54
55    get_instruction_type(&p->ainsn);
56    p->opcode = *p->addr;
57    return 0;
58}
59
60int __kprobes is_prohibited_opcode(kprobe_opcode_t *instruction)
61{
62    switch (*(__u8 *) instruction) {
63    case 0x0c: /* bassm */
64    case 0x0b: /* bsm */
65    case 0x83: /* diag */
66    case 0x44: /* ex */
67    case 0xac: /* stnsm */
68    case 0xad: /* stosm */
69        return -EINVAL;
70    }
71    switch (*(__u16 *) instruction) {
72    case 0x0101: /* pr */
73    case 0xb25a: /* bsa */
74    case 0xb240: /* bakr */
75    case 0xb258: /* bsg */
76    case 0xb218: /* pc */
77    case 0xb228: /* pt */
78    case 0xb98d: /* epsw */
79        return -EINVAL;
80    }
81    return 0;
82}
83
84void __kprobes get_instruction_type(struct arch_specific_insn *ainsn)
85{
86    /* default fixup method */
87    ainsn->fixup = FIXUP_PSW_NORMAL;
88
89    /* save r1 operand */
90    ainsn->reg = (*ainsn->insn & 0xf0) >> 4;
91
92    /* save the instruction length (pop 5-5) in bytes */
93    switch (*(__u8 *) (ainsn->insn) >> 6) {
94    case 0:
95        ainsn->ilen = 2;
96        break;
97    case 1:
98    case 2:
99        ainsn->ilen = 4;
100        break;
101    case 3:
102        ainsn->ilen = 6;
103        break;
104    }
105
106    switch (*(__u8 *) ainsn->insn) {
107    case 0x05: /* balr */
108    case 0x0d: /* basr */
109        ainsn->fixup = FIXUP_RETURN_REGISTER;
110        /* if r2 = 0, no branch will be taken */
111        if ((*ainsn->insn & 0x0f) == 0)
112            ainsn->fixup |= FIXUP_BRANCH_NOT_TAKEN;
113        break;
114    case 0x06: /* bctr */
115    case 0x07: /* bcr */
116        ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
117        break;
118    case 0x45: /* bal */
119    case 0x4d: /* bas */
120        ainsn->fixup = FIXUP_RETURN_REGISTER;
121        break;
122    case 0x47: /* bc */
123    case 0x46: /* bct */
124    case 0x86: /* bxh */
125    case 0x87: /* bxle */
126        ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
127        break;
128    case 0x82: /* lpsw */
129        ainsn->fixup = FIXUP_NOT_REQUIRED;
130        break;
131    case 0xb2: /* lpswe */
132        if (*(((__u8 *) ainsn->insn) + 1) == 0xb2) {
133            ainsn->fixup = FIXUP_NOT_REQUIRED;
134        }
135        break;
136    case 0xa7: /* bras */
137        if ((*ainsn->insn & 0x0f) == 0x05) {
138            ainsn->fixup |= FIXUP_RETURN_REGISTER;
139        }
140        break;
141    case 0xc0:
142        if ((*ainsn->insn & 0x0f) == 0x00 /* larl */
143            || (*ainsn->insn & 0x0f) == 0x05) /* brasl */
144        ainsn->fixup |= FIXUP_RETURN_REGISTER;
145        break;
146    case 0xeb:
147        if (*(((__u8 *) ainsn->insn) + 5 ) == 0x44 || /* bxhg */
148            *(((__u8 *) ainsn->insn) + 5) == 0x45) {/* bxleg */
149            ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
150        }
151        break;
152    case 0xe3: /* bctg */
153        if (*(((__u8 *) ainsn->insn) + 5) == 0x46) {
154            ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
155        }
156        break;
157    }
158}
159
160static int __kprobes swap_instruction(void *aref)
161{
162    struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
163    unsigned long status = kcb->kprobe_status;
164    struct ins_replace_args *args = aref;
165    int rc;
166
167    kcb->kprobe_status = KPROBE_SWAP_INST;
168    rc = probe_kernel_write(args->ptr, &args->new, sizeof(args->new));
169    kcb->kprobe_status = status;
170    return rc;
171}
172
173void __kprobes arch_arm_kprobe(struct kprobe *p)
174{
175    struct ins_replace_args args;
176
177    args.ptr = p->addr;
178    args.old = p->opcode;
179    args.new = BREAKPOINT_INSTRUCTION;
180    stop_machine(swap_instruction, &args, NULL);
181}
182
183void __kprobes arch_disarm_kprobe(struct kprobe *p)
184{
185    struct ins_replace_args args;
186
187    args.ptr = p->addr;
188    args.old = BREAKPOINT_INSTRUCTION;
189    args.new = p->opcode;
190    stop_machine(swap_instruction, &args, NULL);
191}
192
193void __kprobes arch_remove_kprobe(struct kprobe *p)
194{
195    if (p->ainsn.insn) {
196        free_insn_slot(p->ainsn.insn, 0);
197        p->ainsn.insn = NULL;
198    }
199}
200
201static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
202{
203    per_cr_bits kprobe_per_regs[1];
204
205    memset(kprobe_per_regs, 0, sizeof(per_cr_bits));
206    regs->psw.addr = (unsigned long)p->ainsn.insn | PSW_ADDR_AMODE;
207
208    /* Set up the per control reg info, will pass to lctl */
209    kprobe_per_regs[0].em_instruction_fetch = 1;
210    kprobe_per_regs[0].starting_addr = (unsigned long)p->ainsn.insn;
211    kprobe_per_regs[0].ending_addr = (unsigned long)p->ainsn.insn + 1;
212
213    /* Set the PER control regs, turns on single step for this address */
214    __ctl_load(kprobe_per_regs, 9, 11);
215    regs->psw.mask |= PSW_MASK_PER;
216    regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT);
217}
218
219static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
220{
221    kcb->prev_kprobe.kp = kprobe_running();
222    kcb->prev_kprobe.status = kcb->kprobe_status;
223    kcb->prev_kprobe.kprobe_saved_imask = kcb->kprobe_saved_imask;
224    memcpy(kcb->prev_kprobe.kprobe_saved_ctl, kcb->kprobe_saved_ctl,
225                    sizeof(kcb->kprobe_saved_ctl));
226}
227
228static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
229{
230    __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
231    kcb->kprobe_status = kcb->prev_kprobe.status;
232    kcb->kprobe_saved_imask = kcb->prev_kprobe.kprobe_saved_imask;
233    memcpy(kcb->kprobe_saved_ctl, kcb->prev_kprobe.kprobe_saved_ctl,
234                    sizeof(kcb->kprobe_saved_ctl));
235}
236
237static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
238                        struct kprobe_ctlblk *kcb)
239{
240    __get_cpu_var(current_kprobe) = p;
241    /* Save the interrupt and per flags */
242    kcb->kprobe_saved_imask = regs->psw.mask &
243        (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT);
244    /* Save the control regs that govern PER */
245    __ctl_store(kcb->kprobe_saved_ctl, 9, 11);
246}
247
248void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
249                    struct pt_regs *regs)
250{
251    ri->ret_addr = (kprobe_opcode_t *) regs->gprs[14];
252
253    /* Replace the return addr with trampoline addr */
254    regs->gprs[14] = (unsigned long)&kretprobe_trampoline;
255}
256
257static int __kprobes kprobe_handler(struct pt_regs *regs)
258{
259    struct kprobe *p;
260    int ret = 0;
261    unsigned long *addr = (unsigned long *)
262        ((regs->psw.addr & PSW_ADDR_INSN) - 2);
263    struct kprobe_ctlblk *kcb;
264
265    /*
266     * We don't want to be preempted for the entire
267     * duration of kprobe processing
268     */
269    preempt_disable();
270    kcb = get_kprobe_ctlblk();
271
272    /* Check we're not actually recursing */
273    if (kprobe_running()) {
274        p = get_kprobe(addr);
275        if (p) {
276            if (kcb->kprobe_status == KPROBE_HIT_SS &&
277                *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
278                regs->psw.mask &= ~PSW_MASK_PER;
279                regs->psw.mask |= kcb->kprobe_saved_imask;
280                goto no_kprobe;
281            }
282            /* We have reentered the kprobe_handler(), since
283             * another probe was hit while within the handler.
284             * We here save the original kprobes variables and
285             * just single step on the instruction of the new probe
286             * without calling any user handlers.
287             */
288            save_previous_kprobe(kcb);
289            set_current_kprobe(p, regs, kcb);
290            kprobes_inc_nmissed_count(p);
291            prepare_singlestep(p, regs);
292            kcb->kprobe_status = KPROBE_REENTER;
293            return 1;
294        } else {
295            p = __get_cpu_var(current_kprobe);
296            if (p->break_handler && p->break_handler(p, regs)) {
297                goto ss_probe;
298            }
299        }
300        goto no_kprobe;
301    }
302
303    p = get_kprobe(addr);
304    if (!p)
305        /*
306         * No kprobe at this address. The fault has not been
307         * caused by a kprobe breakpoint. The race of breakpoint
308         * vs. kprobe remove does not exist because on s390 we
309         * use stop_machine to arm/disarm the breakpoints.
310         */
311        goto no_kprobe;
312
313    kcb->kprobe_status = KPROBE_HIT_ACTIVE;
314    set_current_kprobe(p, regs, kcb);
315    if (p->pre_handler && p->pre_handler(p, regs))
316        /* handler has already set things up, so skip ss setup */
317        return 1;
318
319ss_probe:
320    prepare_singlestep(p, regs);
321    kcb->kprobe_status = KPROBE_HIT_SS;
322    return 1;
323
324no_kprobe:
325    preempt_enable_no_resched();
326    return ret;
327}
328
329/*
330 * Function return probe trampoline:
331 * - init_kprobes() establishes a probepoint here
332 * - When the probed function returns, this probe
333 * causes the handlers to fire
334 */
335static void __used kretprobe_trampoline_holder(void)
336{
337    asm volatile(".global kretprobe_trampoline\n"
338             "kretprobe_trampoline: bcr 0,0\n");
339}
340
341/*
342 * Called when the probe at kretprobe trampoline is hit
343 */
344static int __kprobes trampoline_probe_handler(struct kprobe *p,
345                          struct pt_regs *regs)
346{
347    struct kretprobe_instance *ri = NULL;
348    struct hlist_head *head, empty_rp;
349    struct hlist_node *node, *tmp;
350    unsigned long flags, orig_ret_address = 0;
351    unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
352    kprobe_opcode_t *correct_ret_addr = NULL;
353
354    INIT_HLIST_HEAD(&empty_rp);
355    kretprobe_hash_lock(current, &head, &flags);
356
357    /*
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.
362     *
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
369     */
370    hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
371        if (ri->task != current)
372            /* another task is sharing our hash bucket */
373            continue;
374
375        orig_ret_address = (unsigned long)ri->ret_addr;
376
377        if (orig_ret_address != trampoline_address)
378            /*
379             * This is the real return address. Any other
380             * instances associated with this task are for
381             * other calls deeper on the call stack
382             */
383            break;
384    }
385
386    kretprobe_assert(ri, orig_ret_address, trampoline_address);
387
388    correct_ret_addr = ri->ret_addr;
389    hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
390        if (ri->task != current)
391            /* another task is sharing our hash bucket */
392            continue;
393
394        orig_ret_address = (unsigned long)ri->ret_addr;
395
396        if (ri->rp && ri->rp->handler) {
397            ri->ret_addr = correct_ret_addr;
398            ri->rp->handler(ri, regs);
399        }
400
401        recycle_rp_inst(ri, &empty_rp);
402
403        if (orig_ret_address != trampoline_address) {
404            /*
405             * This is the real return address. Any other
406             * instances associated with this task are for
407             * other calls deeper on the call stack
408             */
409            break;
410        }
411    }
412
413    regs->psw.addr = orig_ret_address | PSW_ADDR_AMODE;
414
415    reset_current_kprobe();
416    kretprobe_hash_unlock(current, &flags);
417    preempt_enable_no_resched();
418
419    hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
420        hlist_del(&ri->hlist);
421        kfree(ri);
422    }
423    /*
424     * By returning a non-zero value, we are telling
425     * kprobe_handler() that we don't want the post_handler
426     * to run (and have re-enabled preemption)
427     */
428    return 1;
429}
430
431/*
432 * Called after single-stepping. p->addr is the address of the
433 * instruction whose first byte has been replaced by the "breakpoint"
434 * instruction. To avoid the SMP problems that can occur when we
435 * temporarily put back the original opcode to single-step, we
436 * single-stepped a copy of the instruction. The address of this
437 * copy is p->ainsn.insn.
438 */
439static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
440{
441    struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
442
443    regs->psw.addr &= PSW_ADDR_INSN;
444
445    if (p->ainsn.fixup & FIXUP_PSW_NORMAL)
446        regs->psw.addr = (unsigned long)p->addr +
447                ((unsigned long)regs->psw.addr -
448                 (unsigned long)p->ainsn.insn);
449
450    if (p->ainsn.fixup & FIXUP_BRANCH_NOT_TAKEN)
451        if ((unsigned long)regs->psw.addr -
452            (unsigned long)p->ainsn.insn == p->ainsn.ilen)
453            regs->psw.addr = (unsigned long)p->addr + p->ainsn.ilen;
454
455    if (p->ainsn.fixup & FIXUP_RETURN_REGISTER)
456        regs->gprs[p->ainsn.reg] = ((unsigned long)p->addr +
457                        (regs->gprs[p->ainsn.reg] -
458                        (unsigned long)p->ainsn.insn))
459                        | PSW_ADDR_AMODE;
460
461    regs->psw.addr |= PSW_ADDR_AMODE;
462    /* turn off PER mode */
463    regs->psw.mask &= ~PSW_MASK_PER;
464    /* Restore the original per control regs */
465    __ctl_load(kcb->kprobe_saved_ctl, 9, 11);
466    regs->psw.mask |= kcb->kprobe_saved_imask;
467}
468
469static int __kprobes post_kprobe_handler(struct pt_regs *regs)
470{
471    struct kprobe *cur = kprobe_running();
472    struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
473
474    if (!cur)
475        return 0;
476
477    if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
478        kcb->kprobe_status = KPROBE_HIT_SSDONE;
479        cur->post_handler(cur, regs, 0);
480    }
481
482    resume_execution(cur, regs);
483
484    /*Restore back the original saved kprobes variables and continue. */
485    if (kcb->kprobe_status == KPROBE_REENTER) {
486        restore_previous_kprobe(kcb);
487        goto out;
488    }
489    reset_current_kprobe();
490out:
491    preempt_enable_no_resched();
492
493    /*
494     * if somebody else is singlestepping across a probe point, psw mask
495     * will have PER set, in which case, continue the remaining processing
496     * of do_single_step, as if this is not a probe hit.
497     */
498    if (regs->psw.mask & PSW_MASK_PER) {
499        return 0;
500    }
501
502    return 1;
503}
504
505static int __kprobes kprobe_trap_handler(struct pt_regs *regs, int trapnr)
506{
507    struct kprobe *cur = kprobe_running();
508    struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
509    const struct exception_table_entry *entry;
510
511    switch(kcb->kprobe_status) {
512    case KPROBE_SWAP_INST:
513        /* We are here because the instruction replacement failed */
514        return 0;
515    case KPROBE_HIT_SS:
516    case KPROBE_REENTER:
517        /*
518         * We are here because the instruction being single
519         * stepped caused a page fault. We reset the current
520         * kprobe and the nip points back to the probe address
521         * and allow the page fault handler to continue as a
522         * normal page fault.
523         */
524        regs->psw.addr = (unsigned long)cur->addr | PSW_ADDR_AMODE;
525        regs->psw.mask &= ~PSW_MASK_PER;
526        regs->psw.mask |= kcb->kprobe_saved_imask;
527        if (kcb->kprobe_status == KPROBE_REENTER)
528            restore_previous_kprobe(kcb);
529        else {
530            reset_current_kprobe();
531        }
532        preempt_enable_no_resched();
533        break;
534    case KPROBE_HIT_ACTIVE:
535    case KPROBE_HIT_SSDONE:
536        /*
537         * We increment the nmissed count for accounting,
538         * we can also use npre/npostfault count for accouting
539         * these specific fault cases.
540         */
541        kprobes_inc_nmissed_count(cur);
542
543        /*
544         * We come here because instructions in the pre/post
545         * handler caused the page_fault, this could happen
546         * if handler tries to access user space by
547         * copy_from_user(), get_user() etc. Let the
548         * user-specified handler try to fix it first.
549         */
550        if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
551            return 1;
552
553        /*
554         * In case the user-specified fault handler returned
555         * zero, try to fix up.
556         */
557        entry = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
558        if (entry) {
559            regs->psw.addr = entry->fixup | PSW_ADDR_AMODE;
560            return 1;
561        }
562
563        /*
564         * fixup_exception() could not handle it,
565         * Let do_page_fault() fix it.
566         */
567        break;
568    default:
569        break;
570    }
571    return 0;
572}
573
574int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
575{
576    int ret;
577
578    if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
579        local_irq_disable();
580    ret = kprobe_trap_handler(regs, trapnr);
581    if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
582        local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
583    return ret;
584}
585
586/*
587 * Wrapper routine to for handling exceptions.
588 */
589int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
590                       unsigned long val, void *data)
591{
592    struct die_args *args = (struct die_args *)data;
593    struct pt_regs *regs = args->regs;
594    int ret = NOTIFY_DONE;
595
596    if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
597        local_irq_disable();
598
599    switch (val) {
600    case DIE_BPT:
601        if (kprobe_handler(args->regs))
602            ret = NOTIFY_STOP;
603        break;
604    case DIE_SSTEP:
605        if (post_kprobe_handler(args->regs))
606            ret = NOTIFY_STOP;
607        break;
608    case DIE_TRAP:
609        if (!preemptible() && kprobe_running() &&
610            kprobe_trap_handler(args->regs, args->trapnr))
611            ret = NOTIFY_STOP;
612        break;
613    default:
614        break;
615    }
616
617    if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
618        local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
619
620    return ret;
621}
622
623int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
624{
625    struct jprobe *jp = container_of(p, struct jprobe, kp);
626    unsigned long addr;
627    struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
628
629    memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs));
630
631    /* setup return addr to the jprobe handler routine */
632    regs->psw.addr = (unsigned long)(jp->entry) | PSW_ADDR_AMODE;
633    regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT);
634
635    /* r14 is the function return address */
636    kcb->jprobe_saved_r14 = (unsigned long)regs->gprs[14];
637    /* r15 is the stack pointer */
638    kcb->jprobe_saved_r15 = (unsigned long)regs->gprs[15];
639    addr = (unsigned long)kcb->jprobe_saved_r15;
640
641    memcpy(kcb->jprobes_stack, (kprobe_opcode_t *) addr,
642           MIN_STACK_SIZE(addr));
643    return 1;
644}
645
646void __kprobes jprobe_return(void)
647{
648    asm volatile(".word 0x0002");
649}
650
651void __kprobes jprobe_return_end(void)
652{
653    asm volatile("bcr 0,0");
654}
655
656int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
657{
658    struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
659    unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_r15);
660
661    /* Put the regs back */
662    memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));
663    /* put the stack back */
664    memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack,
665           MIN_STACK_SIZE(stack_addr));
666    preempt_enable_no_resched();
667    return 1;
668}
669
670static struct kprobe trampoline_p = {
671    .addr = (kprobe_opcode_t *) & kretprobe_trampoline,
672    .pre_handler = trampoline_probe_handler
673};
674
675int __init arch_init_kprobes(void)
676{
677    return register_kprobe(&trampoline_p);
678}
679
680int __kprobes arch_trampoline_kprobe(struct kprobe *p)
681{
682    if (p->addr == (kprobe_opcode_t *) & kretprobe_trampoline)
683        return 1;
684    return 0;
685}
686

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