[mirror_ubuntu-artful-kernel.git] / arch / ppc64 / kernel / kprobes.c

/*
 *  Kernel Probes (KProbes)
 *  arch/ppc64/kernel/kprobes.c
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright (C) IBM Corporation, 2002, 2004
 *
 * 2002-Oct	Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
 *		Probes initial implementation ( includes contributions from
 *		Rusty Russell).
 * 2004-July	Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
 *		interface to access function arguments.
 * 2004-Nov	Ananth N Mavinakayanahalli <ananth@in.ibm.com> kprobes port
 *		for PPC64
 */

#include <linux/config.h>
#include <linux/kprobes.h>
#include <linux/ptrace.h>
#include <linux/spinlock.h>
#include <linux/preempt.h>
#include <asm/cacheflush.h>
#include <asm/kdebug.h>
#include <asm/sstep.h>

static DECLARE_MUTEX(kprobe_mutex);

static struct kprobe *current_kprobe;
static unsigned long kprobe_status, kprobe_saved_msr;
static struct kprobe *kprobe_prev;
static unsigned long kprobe_status_prev, kprobe_saved_msr_prev;
static struct pt_regs jprobe_saved_regs;

int arch_prepare_kprobe(struct kprobe *p)
{
	int ret = 0;
	kprobe_opcode_t insn = *p->addr;

	if ((unsigned long)p->addr & 0x03) {
		printk("Attempt to register kprobe at an unaligned address\n");
		ret = -EINVAL;
	} else if (IS_MTMSRD(insn) || IS_RFID(insn)) {
		printk("Cannot register a kprobe on rfid or mtmsrd\n");
		ret = -EINVAL;
	}

	/* insn must be on a special executable page on ppc64 */
	if (!ret) {
		up(&kprobe_mutex);
		p->ainsn.insn = get_insn_slot();
		down(&kprobe_mutex);
		if (!p->ainsn.insn)
			ret = -ENOMEM;
	}
	return ret;
}

void arch_copy_kprobe(struct kprobe *p)
{
	memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
	p->opcode = *p->addr;
}

void arch_arm_kprobe(struct kprobe *p)
{
	*p->addr = BREAKPOINT_INSTRUCTION;
	flush_icache_range((unsigned long) p->addr,
			   (unsigned long) p->addr + sizeof(kprobe_opcode_t));
}

void arch_disarm_kprobe(struct kprobe *p)
{
	*p->addr = p->opcode;
	flush_icache_range((unsigned long) p->addr,
			   (unsigned long) p->addr + sizeof(kprobe_opcode_t));
}

void arch_remove_kprobe(struct kprobe *p)
{
	up(&kprobe_mutex);
	free_insn_slot(p->ainsn.insn);
	down(&kprobe_mutex);
}

static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
{
	kprobe_opcode_t insn = *p->ainsn.insn;

	regs->msr |= MSR_SE;

	/* single step inline if it is a trap variant */
	if (IS_TW(insn) || IS_TD(insn) || IS_TWI(insn) || IS_TDI(insn))
		regs->nip = (unsigned long)p->addr;
	else
		regs->nip = (unsigned long)p->ainsn.insn;
}

static inline void save_previous_kprobe(void)
{
	kprobe_prev = current_kprobe;
	kprobe_status_prev = kprobe_status;
	kprobe_saved_msr_prev = kprobe_saved_msr;
}

static inline void restore_previous_kprobe(void)
{
	current_kprobe = kprobe_prev;
	kprobe_status = kprobe_status_prev;
	kprobe_saved_msr = kprobe_saved_msr_prev;
}

static inline int kprobe_handler(struct pt_regs *regs)
{
	struct kprobe *p;
	int ret = 0;
	unsigned int *addr = (unsigned int *)regs->nip;

	/* Check we're not actually recursing */
	if (kprobe_running()) {
		/* We *are* holding lock here, so this is safe.
		   Disarm the probe we just hit, and ignore it. */
		p = get_kprobe(addr);
		if (p) {
			if (kprobe_status == KPROBE_HIT_SS) {
				regs->msr &= ~MSR_SE;
				regs->msr |= kprobe_saved_msr;
				unlock_kprobes();
				goto no_kprobe;
			}
			/* We have reentered the kprobe_handler(), since
			 * another probe was hit while within the handler.
			 * We here save the original kprobes variables and
			 * just single step on the instruction of the new probe
			 * without calling any user handlers.
			 */
			save_previous_kprobe();
			current_kprobe = p;
			kprobe_saved_msr = regs->msr;
			p->nmissed++;
			prepare_singlestep(p, regs);
			kprobe_status = KPROBE_REENTER;
			return 1;
		} else {
			p = current_kprobe;
			if (p->break_handler && p->break_handler(p, regs)) {
				goto ss_probe;
			}
		}
		/* If it's not ours, can't be delete race, (we hold lock). */
		goto no_kprobe;
	}

	lock_kprobes();
	p = get_kprobe(addr);
	if (!p) {
		unlock_kprobes();
		if (*addr != BREAKPOINT_INSTRUCTION) {
			/*
			 * PowerPC has multiple variants of the "trap"
			 * instruction. If the current instruction is a
			 * trap variant, it could belong to someone else
			 */
			kprobe_opcode_t cur_insn = *addr;
			if (IS_TW(cur_insn) || IS_TD(cur_insn) ||
					IS_TWI(cur_insn) || IS_TDI(cur_insn))
		       		goto no_kprobe;
			/*
			 * The breakpoint instruction was removed right
			 * after we hit it.  Another cpu has removed
			 * either a probepoint or a debugger breakpoint
			 * at this address.  In either case, no further
			 * handling of this interrupt is appropriate.
			 */
			ret = 1;
		}
		/* Not one of ours: let kernel handle it */
		goto no_kprobe;
	}

	kprobe_status = KPROBE_HIT_ACTIVE;
	current_kprobe = p;
	kprobe_saved_msr = regs->msr;
	if (p->pre_handler && p->pre_handler(p, regs))
		/* handler has already set things up, so skip ss setup */
		return 1;

ss_probe:
	prepare_singlestep(p, regs);
	kprobe_status = KPROBE_HIT_SS;
	/*
	 * This preempt_disable() matches the preempt_enable_no_resched()
	 * in post_kprobe_handler().
	 */
	preempt_disable();
	return 1;

no_kprobe:
	return ret;
}

/*
 * Called after single-stepping.  p->addr is the address of the
 * instruction whose first byte has been replaced by the "breakpoint"
 * instruction.  To avoid the SMP problems that can occur when we
 * temporarily put back the original opcode to single-step, we
 * single-stepped a copy of the instruction.  The address of this
 * copy is p->ainsn.insn.
 */
static void resume_execution(struct kprobe *p, struct pt_regs *regs)
{
	int ret;
	unsigned int insn = *p->ainsn.insn;

	regs->nip = (unsigned long)p->addr;
	ret = emulate_step(regs, insn);
	if (ret == 0)
		regs->nip = (unsigned long)p->addr + 4;
}

static inline int post_kprobe_handler(struct pt_regs *regs)
{
	if (!kprobe_running())
		return 0;

	if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) {
		kprobe_status = KPROBE_HIT_SSDONE;
		current_kprobe->post_handler(current_kprobe, regs, 0);
	}

	resume_execution(current_kprobe, regs);
	regs->msr |= kprobe_saved_msr;

	/*Restore back the original saved kprobes variables and continue. */
	if (kprobe_status == KPROBE_REENTER) {
		restore_previous_kprobe();
		goto out;
	}
	unlock_kprobes();
out:
	preempt_enable_no_resched();

	/*
	 * if somebody else is singlestepping across a probe point, msr
	 * will have SE set, in which case, continue the remaining processing
	 * of do_debug, as if this is not a probe hit.
	 */
	if (regs->msr & MSR_SE)
		return 0;

	return 1;
}

/* Interrupts disabled, kprobe_lock held. */
static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
{
	if (current_kprobe->fault_handler
	    && current_kprobe->fault_handler(current_kprobe, regs, trapnr))
		return 1;

	if (kprobe_status & KPROBE_HIT_SS) {
		resume_execution(current_kprobe, regs);
		regs->msr &= ~MSR_SE;
		regs->msr |= kprobe_saved_msr;

		unlock_kprobes();
		preempt_enable_no_resched();
	}
	return 0;
}

/*
 * Wrapper routine to for handling exceptions.
 */
int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val,
			     void *data)
{
	struct die_args *args = (struct die_args *)data;
	int ret = NOTIFY_DONE;

	/*
	 * Interrupts are not disabled here.  We need to disable
	 * preemption, because kprobe_running() uses smp_processor_id().
	 */
	preempt_disable();
	switch (val) {
	case DIE_BPT:
		if (kprobe_handler(args->regs))
			ret = NOTIFY_STOP;
		break;
	case DIE_SSTEP:
		if (post_kprobe_handler(args->regs))
			ret = NOTIFY_STOP;
		break;
	case DIE_GPF:
	case DIE_PAGE_FAULT:
		if (kprobe_running() &&
		    kprobe_fault_handler(args->regs, args->trapnr))
			ret = NOTIFY_STOP;
		break;
	default:
		break;
	}
	preempt_enable();
	return ret;
}

int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
	struct jprobe *jp = container_of(p, struct jprobe, kp);

	memcpy(&jprobe_saved_regs, regs, sizeof(struct pt_regs));

	/* setup return addr to the jprobe handler routine */
	regs->nip = (unsigned long)(((func_descr_t *)jp->entry)->entry);
	regs->gpr[2] = (unsigned long)(((func_descr_t *)jp->entry)->toc);

	return 1;
}

void jprobe_return(void)
{
	asm volatile("trap" ::: "memory");
}

void jprobe_return_end(void)
{
};

int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
{
	/*
	 * FIXME - we should ideally be validating that we got here 'cos
	 * of the "trap" in jprobe_return() above, before restoring the
	 * saved regs...
	 */
	memcpy(regs, &jprobe_saved_regs, sizeof(struct pt_regs));
	return 1;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Kernel Probes (KProbes)
	3	* arch/ppc64/kernel/kprobes.c
	4	*
	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.
	9	*
	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.
	14	*
	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.
	18	*
	19	* Copyright (C) IBM Corporation, 2002, 2004
	20	*
	21	* 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
	22	* Probes initial implementation ( includes contributions from
	23	* Rusty Russell).
	24	* 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
	25	* interface to access function arguments.
	26	* 2004-Nov Ananth N Mavinakayanahalli <ananth@in.ibm.com> kprobes port
	27	* for PPC64
	28	*/
	29
	30	#include <linux/config.h>
	31	#include <linux/kprobes.h>
	32	#include <linux/ptrace.h>
	33	#include <linux/spinlock.h>
	34	#include <linux/preempt.h>
7e1048b1	35	#include <asm/cacheflush.h>
1da177e4 LT	36	#include <asm/kdebug.h>
	37	#include <asm/sstep.h>
	38
9ec4b1f3 AM	39	static DECLARE_MUTEX(kprobe_mutex);
9ec4b1f3 AM	40
1da177e4 LT	41	static struct kprobe *current_kprobe;
1da177e4 LT	42	static unsigned long kprobe_status, kprobe_saved_msr;
42cc2060 PP	43	static struct kprobe *kprobe_prev;
42cc2060 PP	44	static unsigned long kprobe_status_prev, kprobe_saved_msr_prev;
1da177e4 LT	45	static struct pt_regs jprobe_saved_regs;
	46
	47	int arch_prepare_kprobe(struct kprobe *p)
	48	{
63224d1e	49	int ret = 0;
1da177e4 LT	50	kprobe_opcode_t insn = *p->addr;
1da177e4 LT	51
63224d1e AM	52	if ((unsigned long)p->addr & 0x03) {
	53	printk("Attempt to register kprobe at an unaligned address\n");
	54	ret = -EINVAL;
	55	} else if (IS_MTMSRD(insn) \|\| IS_RFID(insn)) {
	56	printk("Cannot register a kprobe on rfid or mtmsrd\n");
	57	ret = -EINVAL;
	58	}
9ec4b1f3 AM	59
	60	/* insn must be on a special executable page on ppc64 */
	61	if (!ret) {
	62	up(&kprobe_mutex);
	63	p->ainsn.insn = get_insn_slot();
	64	down(&kprobe_mutex);
	65	if (!p->ainsn.insn)
	66	ret = -ENOMEM;
	67	}
63224d1e	68	return ret;
1da177e4 LT	69	}
	70
	71	void arch_copy_kprobe(struct kprobe *p)
	72	{
	73	memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
7e1048b1	74	p->opcode = *p->addr;
1da177e4 LT	75	}
1da177e4 LT	76
7e1048b1	77	void arch_arm_kprobe(struct kprobe *p)
1da177e4	78	{
7e1048b1 RL	79	*p->addr = BREAKPOINT_INSTRUCTION;
	80	flush_icache_range((unsigned long) p->addr,
	81	(unsigned long) p->addr + sizeof(kprobe_opcode_t));
1da177e4 LT	82	}
1da177e4 LT	83
7e1048b1	84	void arch_disarm_kprobe(struct kprobe *p)
1da177e4 LT	85	{
1da177e4 LT	86	*p->addr = p->opcode;
7e1048b1 RL	87	flush_icache_range((unsigned long) p->addr,
	88	(unsigned long) p->addr + sizeof(kprobe_opcode_t));
	89	}
	90
	91	void arch_remove_kprobe(struct kprobe *p)
	92	{
9ec4b1f3 AM	93	up(&kprobe_mutex);
	94	free_insn_slot(p->ainsn.insn);
	95	down(&kprobe_mutex);
1da177e4 LT	96	}
	97
	98	static inline void prepare_singlestep(struct kprobe p, struct pt_regs regs)
	99	{
9ec4b1f3 AM	100	kprobe_opcode_t insn = *p->ainsn.insn;
9ec4b1f3 AM	101
1da177e4	102	regs->msr \|= MSR_SE;
9ec4b1f3 AM	103
	104	/* single step inline if it is a trap variant */
	105	if (IS_TW(insn) \|\| IS_TD(insn) \|\| IS_TWI(insn) \|\| IS_TDI(insn))
1da177e4 LT	106	regs->nip = (unsigned long)p->addr;
1da177e4 LT	107	else
9ec4b1f3	108	regs->nip = (unsigned long)p->ainsn.insn;
1da177e4 LT	109	}
1da177e4 LT	110
42cc2060 PP	111	static inline void save_previous_kprobe(void)
	112	{
	113	kprobe_prev = current_kprobe;
	114	kprobe_status_prev = kprobe_status;
	115	kprobe_saved_msr_prev = kprobe_saved_msr;
	116	}
	117
	118	static inline void restore_previous_kprobe(void)
	119	{
	120	current_kprobe = kprobe_prev;
	121	kprobe_status = kprobe_status_prev;
	122	kprobe_saved_msr = kprobe_saved_msr_prev;
	123	}
	124
1da177e4 LT	125	static inline int kprobe_handler(struct pt_regs *regs)
	126	{
	127	struct kprobe *p;
	128	int ret = 0;
	129	unsigned int addr = (unsigned int )regs->nip;
	130
	131	/* Check we're not actually recursing */
	132	if (kprobe_running()) {
	133	/* We are holding lock here, so this is safe.
	134	Disarm the probe we just hit, and ignore it. */
	135	p = get_kprobe(addr);
	136	if (p) {
	137	if (kprobe_status == KPROBE_HIT_SS) {
	138	regs->msr &= ~MSR_SE;
	139	regs->msr \|= kprobe_saved_msr;
	140	unlock_kprobes();
	141	goto no_kprobe;
	142	}
42cc2060 PP	143	/* We have reentered the kprobe_handler(), since
	144	* another probe was hit while within the handler.
	145	* We here save the original kprobes variables and
	146	* just single step on the instruction of the new probe
	147	* without calling any user handlers.
	148	*/
	149	save_previous_kprobe();
	150	current_kprobe = p;
	151	kprobe_saved_msr = regs->msr;
	152	p->nmissed++;
	153	prepare_singlestep(p, regs);
	154	kprobe_status = KPROBE_REENTER;
	155	return 1;
1da177e4 LT	156	} else {
	157	p = current_kprobe;
	158	if (p->break_handler && p->break_handler(p, regs)) {
	159	goto ss_probe;
	160	}
	161	}
	162	/* If it's not ours, can't be delete race, (we hold lock). */
	163	goto no_kprobe;
	164	}
	165
	166	lock_kprobes();
	167	p = get_kprobe(addr);
	168	if (!p) {
	169	unlock_kprobes();
	170	if (*addr != BREAKPOINT_INSTRUCTION) {
	171	/*
	172	* PowerPC has multiple variants of the "trap"
	173	* instruction. If the current instruction is a
	174	* trap variant, it could belong to someone else
	175	*/
	176	kprobe_opcode_t cur_insn = *addr;
	177	if (IS_TW(cur_insn) \|\| IS_TD(cur_insn) \|\|
	178	IS_TWI(cur_insn) \|\| IS_TDI(cur_insn))
	179	goto no_kprobe;
	180	/*
	181	* The breakpoint instruction was removed right
	182	* after we hit it. Another cpu has removed
	183	* either a probepoint or a debugger breakpoint
	184	* at this address. In either case, no further
	185	* handling of this interrupt is appropriate.
	186	*/
	187	ret = 1;
	188	}
	189	/* Not one of ours: let kernel handle it */
	190	goto no_kprobe;
	191	}
	192
	193	kprobe_status = KPROBE_HIT_ACTIVE;
	194	current_kprobe = p;
	195	kprobe_saved_msr = regs->msr;
	196	if (p->pre_handler && p->pre_handler(p, regs))
	197	/* handler has already set things up, so skip ss setup */
	198	return 1;
	199
	200	ss_probe:
	201	prepare_singlestep(p, regs);
	202	kprobe_status = KPROBE_HIT_SS;
	203	/*
	204	* This preempt_disable() matches the preempt_enable_no_resched()
	205	* in post_kprobe_handler().
	206	*/
	207	preempt_disable();
	208	return 1;
	209
	210	no_kprobe:
	211	return ret;
	212	}
	213
	214	/*
	215	* Called after single-stepping. p->addr is the address of the
	216	* instruction whose first byte has been replaced by the "breakpoint"
	217	* instruction. To avoid the SMP problems that can occur when we
	218	* temporarily put back the original opcode to single-step, we
	219	* single-stepped a copy of the instruction. The address of this
220	* copy is p->ainsn.insn.
221	*/
222	static void resume_execution(struct kprobe p, struct pt_regs regs)
223	{
224	int ret;
9ec4b1f3	225	unsigned int insn = *p->ainsn.insn;
1da177e4 LT	226
1da177e4 LT	227	regs->nip = (unsigned long)p->addr;
9ec4b1f3	228	ret = emulate_step(regs, insn);
1da177e4 LT	229	if (ret == 0)
1da177e4 LT	230	regs->nip = (unsigned long)p->addr + 4;
1da177e4 LT	231	}
	232
	233	static inline int post_kprobe_handler(struct pt_regs *regs)
	234	{
	235	if (!kprobe_running())
	236	return 0;
	237
42cc2060 PP	238	if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) {
42cc2060 PP	239	kprobe_status = KPROBE_HIT_SSDONE;
1da177e4	240	current_kprobe->post_handler(current_kprobe, regs, 0);
42cc2060	241	}
1da177e4 LT	242
	243	resume_execution(current_kprobe, regs);
	244	regs->msr \|= kprobe_saved_msr;
	245
42cc2060 PP	246	/Restore back the original saved kprobes variables and continue. /
	247	if (kprobe_status == KPROBE_REENTER) {
	248	restore_previous_kprobe();
	249	goto out;
	250	}
1da177e4	251	unlock_kprobes();
42cc2060	252	out:
1da177e4 LT	253	preempt_enable_no_resched();
	254
	255	/*
	256	* if somebody else is singlestepping across a probe point, msr
	257	* will have SE set, in which case, continue the remaining processing
	258	* of do_debug, as if this is not a probe hit.
	259	*/
	260	if (regs->msr & MSR_SE)
	261	return 0;
	262
	263	return 1;
	264	}
	265
	266	/* Interrupts disabled, kprobe_lock held. */
	267	static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
	268	{
	269	if (current_kprobe->fault_handler
	270	&& current_kprobe->fault_handler(current_kprobe, regs, trapnr))
	271	return 1;
	272
	273	if (kprobe_status & KPROBE_HIT_SS) {
	274	resume_execution(current_kprobe, regs);
f829fd23	275	regs->msr &= ~MSR_SE;
1da177e4 LT	276	regs->msr \|= kprobe_saved_msr;
	277
	278	unlock_kprobes();
	279	preempt_enable_no_resched();
	280	}
	281	return 0;
	282	}
	283
	284	/*
	285	* Wrapper routine to for handling exceptions.
	286	*/
	287	int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val,
	288	void *data)
	289	{
	290	struct die_args args = (struct die_args )data;
	291	int ret = NOTIFY_DONE;
	292
	293	/*
	294	* Interrupts are not disabled here. We need to disable
	295	* preemption, because kprobe_running() uses smp_processor_id().
	296	*/
	297	preempt_disable();
	298	switch (val) {
1da177e4 LT	299	case DIE_BPT:
	300	if (kprobe_handler(args->regs))
	301	ret = NOTIFY_STOP;
	302	break;
	303	case DIE_SSTEP:
	304	if (post_kprobe_handler(args->regs))
	305	ret = NOTIFY_STOP;
	306	break;
	307	case DIE_GPF:
	308	case DIE_PAGE_FAULT:
	309	if (kprobe_running() &&
	310	kprobe_fault_handler(args->regs, args->trapnr))
	311	ret = NOTIFY_STOP;
	312	break;
	313	default:
	314	break;
	315	}
	316	preempt_enable();
	317	return ret;
	318	}
	319
	320	int setjmp_pre_handler(struct kprobe p, struct pt_regs regs)
	321	{
	322	struct jprobe *jp = container_of(p, struct jprobe, kp);
	323
	324	memcpy(&jprobe_saved_regs, regs, sizeof(struct pt_regs));
	325
	326	/* setup return addr to the jprobe handler routine */
	327	regs->nip = (unsigned long)(((func_descr_t *)jp->entry)->entry);
	328	regs->gpr[2] = (unsigned long)(((func_descr_t *)jp->entry)->toc);
	329
	330	return 1;
	331	}
	332
	333	void jprobe_return(void)
	334	{
	335	asm volatile("trap" ::: "memory");
	336	}
	337
	338	void jprobe_return_end(void)
	339	{
	340	};
	341
	342	int longjmp_break_handler(struct kprobe p, struct pt_regs regs)
	343	{
	344	/*
	345	* FIXME - we should ideally be validating that we got here 'cos
	346	* of the "trap" in jprobe_return() above, before restoring the
	347	* saved regs...
	348	*/
	349	memcpy(regs, &jprobe_saved_regs, sizeof(struct pt_regs));
	350	return 1;
	351	}