[deliverable/linux.git] / kernel / kprobes.c

/*
 *  Kernel Probes (KProbes)
 *  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 suggestions from
 *		Rusty Russell).
 * 2004-Aug	Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with
 *		hlists and exceptions notifier as suggested by Andi Kleen.
 * 2004-July	Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
 *		interface to access function arguments.
 * 2004-Sep	Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
 *		exceptions notifier to be first on the priority list.
 * 2005-May	Hien Nguyen <hien@us.ibm.com>, Jim Keniston
 *		<jkenisto@us.ibm.com> and Prasanna S Panchamukhi
 *		<prasanna@in.ibm.com> added function-return probes.
 */
#include <linux/kprobes.h>
#include <linux/spinlock.h>
#include <linux/hash.h>
#include <linux/init.h>
#include <linux/module.h>
#include <asm/cacheflush.h>
#include <asm/errno.h>
#include <asm/kdebug.h>

#define KPROBE_HASH_BITS 6
#define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)

static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];

unsigned int kprobe_cpu = NR_CPUS;
static DEFINE_SPINLOCK(kprobe_lock);
static struct kprobe *curr_kprobe;

/* Locks kprobe: irqs must be disabled */
void lock_kprobes(void)
{
	spin_lock(&kprobe_lock);
	kprobe_cpu = smp_processor_id();
}

void unlock_kprobes(void)
{
	kprobe_cpu = NR_CPUS;
	spin_unlock(&kprobe_lock);
}

/* You have to be holding the kprobe_lock */
struct kprobe *get_kprobe(void *addr)
{
	struct hlist_head *head;
	struct hlist_node *node;

	head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
	hlist_for_each(node, head) {
		struct kprobe *p = hlist_entry(node, struct kprobe, hlist);
		if (p->addr == addr)
			return p;
	}
	return NULL;
}

/*
 * Aggregate handlers for multiple kprobes support - these handlers
 * take care of invoking the individual kprobe handlers on p->list
 */
static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
	struct kprobe *kp;

	list_for_each_entry(kp, &p->list, list) {
		if (kp->pre_handler) {
			curr_kprobe = kp;
			kp->pre_handler(kp, regs);
			curr_kprobe = NULL;
		}
	}
	return 0;
}

static void aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
			      unsigned long flags)
{
	struct kprobe *kp;

	list_for_each_entry(kp, &p->list, list) {
		if (kp->post_handler) {
			curr_kprobe = kp;
			kp->post_handler(kp, regs, flags);
			curr_kprobe = NULL;
		}
	}
	return;
}

static int aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
			      int trapnr)
{
	/*
	 * if we faulted "during" the execution of a user specified
	 * probe handler, invoke just that probe's fault handler
	 */
	if (curr_kprobe && curr_kprobe->fault_handler) {
		if (curr_kprobe->fault_handler(curr_kprobe, regs, trapnr))
			return 1;
	}
	return 0;
}

struct kprobe trampoline_p = {
		.addr = (kprobe_opcode_t *) &kretprobe_trampoline,
		.pre_handler = trampoline_probe_handler,
		.post_handler = trampoline_post_handler
};

struct kretprobe_instance *get_free_rp_inst(struct kretprobe *rp)
{
	struct hlist_node *node;
	struct kretprobe_instance *ri;
	hlist_for_each_entry(ri, node, &rp->free_instances, uflist)
		return ri;
	return NULL;
}

static struct kretprobe_instance *get_used_rp_inst(struct kretprobe *rp)
{
	struct hlist_node *node;
	struct kretprobe_instance *ri;
	hlist_for_each_entry(ri, node, &rp->used_instances, uflist)
		return ri;
	return NULL;
}

struct kretprobe_instance *get_rp_inst(void *sara)
{
	struct hlist_head *head;
	struct hlist_node *node;
	struct task_struct *tsk;
	struct kretprobe_instance *ri;

	tsk = arch_get_kprobe_task(sara);
	head = &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)];
	hlist_for_each_entry(ri, node, head, hlist) {
		if (ri->stack_addr == sara)
			return ri;
	}
	return NULL;
}

void add_rp_inst(struct kretprobe_instance *ri)
{
	struct task_struct *tsk;
	/*
	 * Remove rp inst off the free list -
	 * Add it back when probed function returns
	 */
	hlist_del(&ri->uflist);
	tsk = arch_get_kprobe_task(ri->stack_addr);
	/* Add rp inst onto table */
	INIT_HLIST_NODE(&ri->hlist);
	hlist_add_head(&ri->hlist,
			&kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)]);

	/* Also add this rp inst to the used list. */
	INIT_HLIST_NODE(&ri->uflist);
	hlist_add_head(&ri->uflist, &ri->rp->used_instances);
}

void recycle_rp_inst(struct kretprobe_instance *ri)
{
	/* remove rp inst off the rprobe_inst_table */
	hlist_del(&ri->hlist);
	if (ri->rp) {
		/* remove rp inst off the used list */
		hlist_del(&ri->uflist);
		/* put rp inst back onto the free list */
		INIT_HLIST_NODE(&ri->uflist);
		hlist_add_head(&ri->uflist, &ri->rp->free_instances);
	} else
		/* Unregistering */
		kfree(ri);
}

struct hlist_head * kretprobe_inst_table_head(struct task_struct *tsk)
{
	return &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)];
}

struct kretprobe_instance *get_rp_inst_tsk(struct task_struct *tk)
{
	struct task_struct *tsk;
	struct hlist_head *head;
	struct hlist_node *node;
	struct kretprobe_instance *ri;

	head = &kretprobe_inst_table[hash_ptr(tk, KPROBE_HASH_BITS)];

	hlist_for_each_entry(ri, node, head, hlist) {
		tsk = arch_get_kprobe_task(ri->stack_addr);
		if (tsk == tk)
			return ri;
	}
	return NULL;
}

/*
 * This function is called from do_exit or do_execv when task tk's stack is
 * about to be recycled. Recycle any function-return probe instances
 * associated with this task. These represent probed functions that have
 * been called but may never return.
 */
void kprobe_flush_task(struct task_struct *tk)
{
	unsigned long flags = 0;
	spin_lock_irqsave(&kprobe_lock, flags);
	arch_kprobe_flush_task(tk);
	spin_unlock_irqrestore(&kprobe_lock, flags);
}

/*
 * This kprobe pre_handler is registered with every kretprobe. When probe
 * hits it will set up the return probe.
 */
static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
{
	struct kretprobe *rp = container_of(p, struct kretprobe, kp);

	/*TODO: consider to only swap the RA after the last pre_handler fired */
	arch_prepare_kretprobe(rp, regs);
	return 0;
}

static inline void free_rp_inst(struct kretprobe *rp)
{
	struct kretprobe_instance *ri;
	while ((ri = get_free_rp_inst(rp)) != NULL) {
		hlist_del(&ri->uflist);
		kfree(ri);
	}
}

/*
 * Fill in the required fields of the "manager kprobe". Replace the
 * earlier kprobe in the hlist with the manager kprobe
 */
static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
{
	ap->addr = p->addr;
	memcpy(&ap->opcode, &p->opcode, sizeof(kprobe_opcode_t));
	memcpy(&ap->ainsn, &p->ainsn, sizeof(struct arch_specific_insn));

	ap->pre_handler = aggr_pre_handler;
	ap->post_handler = aggr_post_handler;
	ap->fault_handler = aggr_fault_handler;

	INIT_LIST_HEAD(&ap->list);
	list_add(&p->list, &ap->list);

	INIT_HLIST_NODE(&ap->hlist);
	hlist_del(&p->hlist);
	hlist_add_head(&ap->hlist,
		&kprobe_table[hash_ptr(ap->addr, KPROBE_HASH_BITS)]);
}

/*
 * This is the second or subsequent kprobe at the address - handle
 * the intricacies
 * TODO: Move kcalloc outside the spinlock
 */
static int register_aggr_kprobe(struct kprobe *old_p, struct kprobe *p)
{
	int ret = 0;
	struct kprobe *ap;

	if (old_p->break_handler || p->break_handler) {
		ret = -EEXIST;	/* kprobe and jprobe can't (yet) coexist */
	} else if (old_p->pre_handler == aggr_pre_handler) {
		list_add(&p->list, &old_p->list);
	} else {
		ap = kcalloc(1, sizeof(struct kprobe), GFP_ATOMIC);
		if (!ap)
			return -ENOMEM;
		add_aggr_kprobe(ap, old_p);
		list_add(&p->list, &ap->list);
	}
	return ret;
}

/* kprobe removal house-keeping routines */
static inline void cleanup_kprobe(struct kprobe *p, unsigned long flags)
{
	arch_disarm_kprobe(p);
	hlist_del(&p->hlist);
	spin_unlock_irqrestore(&kprobe_lock, flags);
	arch_remove_kprobe(p);
}

static inline void cleanup_aggr_kprobe(struct kprobe *old_p,
		struct kprobe *p, unsigned long flags)
{
	list_del(&p->list);
	if (list_empty(&old_p->list)) {
		cleanup_kprobe(old_p, flags);
		kfree(old_p);
	} else
		spin_unlock_irqrestore(&kprobe_lock, flags);
}

int register_kprobe(struct kprobe *p)
{
	int ret = 0;
	unsigned long flags = 0;
	struct kprobe *old_p;

	if ((ret = arch_prepare_kprobe(p)) != 0) {
		goto rm_kprobe;
	}
	spin_lock_irqsave(&kprobe_lock, flags);
	old_p = get_kprobe(p->addr);
	p->nmissed = 0;
	if (old_p) {
		ret = register_aggr_kprobe(old_p, p);
		goto out;
	}

	arch_copy_kprobe(p);
	INIT_HLIST_NODE(&p->hlist);
	hlist_add_head(&p->hlist,
		       &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);

  	arch_arm_kprobe(p);

out:
	spin_unlock_irqrestore(&kprobe_lock, flags);
rm_kprobe:
	if (ret == -EEXIST)
		arch_remove_kprobe(p);
	return ret;
}

void unregister_kprobe(struct kprobe *p)
{
	unsigned long flags;
	struct kprobe *old_p;

	spin_lock_irqsave(&kprobe_lock, flags);
	old_p = get_kprobe(p->addr);
	if (old_p) {
		if (old_p->pre_handler == aggr_pre_handler)
			cleanup_aggr_kprobe(old_p, p, flags);
		else
			cleanup_kprobe(p, flags);
	} else
		spin_unlock_irqrestore(&kprobe_lock, flags);
}

static struct notifier_block kprobe_exceptions_nb = {
	.notifier_call = kprobe_exceptions_notify,
	.priority = 0x7fffffff /* we need to notified first */
};

int register_jprobe(struct jprobe *jp)
{
	/* Todo: Verify probepoint is a function entry point */
	jp->kp.pre_handler = setjmp_pre_handler;
	jp->kp.break_handler = longjmp_break_handler;

	return register_kprobe(&jp->kp);
}

void unregister_jprobe(struct jprobe *jp)
{
	unregister_kprobe(&jp->kp);
}

#ifdef ARCH_SUPPORTS_KRETPROBES

int register_kretprobe(struct kretprobe *rp)
{
	int ret = 0;
	struct kretprobe_instance *inst;
	int i;

	rp->kp.pre_handler = pre_handler_kretprobe;

	/* Pre-allocate memory for max kretprobe instances */
	if (rp->maxactive <= 0) {
#ifdef CONFIG_PREEMPT
		rp->maxactive = max(10, 2 * NR_CPUS);
#else
		rp->maxactive = NR_CPUS;
#endif
	}
	INIT_HLIST_HEAD(&rp->used_instances);
	INIT_HLIST_HEAD(&rp->free_instances);
	for (i = 0; i < rp->maxactive; i++) {
		inst = kmalloc(sizeof(struct kretprobe_instance), GFP_KERNEL);
		if (inst == NULL) {
			free_rp_inst(rp);
			return -ENOMEM;
		}
		INIT_HLIST_NODE(&inst->uflist);
		hlist_add_head(&inst->uflist, &rp->free_instances);
	}

	rp->nmissed = 0;
	/* Establish function entry probe point */
	if ((ret = register_kprobe(&rp->kp)) != 0)
		free_rp_inst(rp);
	return ret;
}

#else /* ARCH_SUPPORTS_KRETPROBES */

int register_kretprobe(struct kretprobe *rp)
{
	return -ENOSYS;
}

#endif /* ARCH_SUPPORTS_KRETPROBES */

void unregister_kretprobe(struct kretprobe *rp)
{
	unsigned long flags;
	struct kretprobe_instance *ri;

	unregister_kprobe(&rp->kp);
	/* No race here */
	spin_lock_irqsave(&kprobe_lock, flags);
	free_rp_inst(rp);
	while ((ri = get_used_rp_inst(rp)) != NULL) {
		ri->rp = NULL;
		hlist_del(&ri->uflist);
	}
	spin_unlock_irqrestore(&kprobe_lock, flags);
}

static int __init init_kprobes(void)
{
	int i, err = 0;

	/* FIXME allocate the probe table, currently defined statically */
	/* initialize all list heads */
	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
		INIT_HLIST_HEAD(&kprobe_table[i]);
		INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
	}

	err = register_die_notifier(&kprobe_exceptions_nb);
	/* Register the trampoline probe for return probe */
	register_kprobe(&trampoline_p);
	return err;
}

__initcall(init_kprobes);

EXPORT_SYMBOL_GPL(register_kprobe);
EXPORT_SYMBOL_GPL(unregister_kprobe);
EXPORT_SYMBOL_GPL(register_jprobe);
EXPORT_SYMBOL_GPL(unregister_jprobe);
EXPORT_SYMBOL_GPL(jprobe_return);
EXPORT_SYMBOL_GPL(register_kretprobe);
EXPORT_SYMBOL_GPL(unregister_kretprobe);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Kernel Probes (KProbes)
	3	* 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 suggestions from
	23	* Rusty Russell).
	24	* 2004-Aug Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with
	25	* hlists and exceptions notifier as suggested by Andi Kleen.
	26	* 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
	27	* interface to access function arguments.
	28	* 2004-Sep Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
	29	* exceptions notifier to be first on the priority list.
b94cce92 HN	30	* 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston
	31	* <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
	32	* <prasanna@in.ibm.com> added function-return probes.
1da177e4 LT	33	*/
	34	#include <linux/kprobes.h>
	35	#include <linux/spinlock.h>
	36	#include <linux/hash.h>
	37	#include <linux/init.h>
	38	#include <linux/module.h>
	39	#include <asm/cacheflush.h>
	40	#include <asm/errno.h>
	41	#include <asm/kdebug.h>
	42
	43	#define KPROBE_HASH_BITS 6
	44	#define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
	45
	46	static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
b94cce92	47	static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
1da177e4 LT	48
	49	unsigned int kprobe_cpu = NR_CPUS;
	50	static DEFINE_SPINLOCK(kprobe_lock);
64f562c6	51	static struct kprobe *curr_kprobe;
1da177e4 LT	52
	53	/* Locks kprobe: irqs must be disabled */
	54	void lock_kprobes(void)
	55	{
	56	spin_lock(&kprobe_lock);
	57	kprobe_cpu = smp_processor_id();
	58	}
	59
	60	void unlock_kprobes(void)
	61	{
	62	kprobe_cpu = NR_CPUS;
	63	spin_unlock(&kprobe_lock);
	64	}
	65
	66	/* You have to be holding the kprobe_lock */
	67	struct kprobe get_kprobe(void addr)
	68	{
	69	struct hlist_head *head;
	70	struct hlist_node *node;
	71
	72	head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
	73	hlist_for_each(node, head) {
	74	struct kprobe *p = hlist_entry(node, struct kprobe, hlist);
	75	if (p->addr == addr)
	76	return p;
	77	}
	78	return NULL;
	79	}
	80
64f562c6 AM	81	/*
	82	* Aggregate handlers for multiple kprobes support - these handlers
	83	* take care of invoking the individual kprobe handlers on p->list
	84	*/
b94cce92	85	static int aggr_pre_handler(struct kprobe p, struct pt_regs regs)
64f562c6 AM	86	{
	87	struct kprobe *kp;
	88
	89	list_for_each_entry(kp, &p->list, list) {
	90	if (kp->pre_handler) {
	91	curr_kprobe = kp;
	92	kp->pre_handler(kp, regs);
	93	curr_kprobe = NULL;
	94	}
	95	}
	96	return 0;
	97	}
	98
b94cce92 HN	99	static void aggr_post_handler(struct kprobe p, struct pt_regs regs,
b94cce92 HN	100	unsigned long flags)
64f562c6 AM	101	{
	102	struct kprobe *kp;
	103
	104	list_for_each_entry(kp, &p->list, list) {
	105	if (kp->post_handler) {
	106	curr_kprobe = kp;
	107	kp->post_handler(kp, regs, flags);
	108	curr_kprobe = NULL;
	109	}
	110	}
	111	return;
	112	}
	113
b94cce92 HN	114	static int aggr_fault_handler(struct kprobe p, struct pt_regs regs,
b94cce92 HN	115	int trapnr)
64f562c6 AM	116	{
	117	/*
	118	* if we faulted "during" the execution of a user specified
	119	* probe handler, invoke just that probe's fault handler
	120	*/
	121	if (curr_kprobe && curr_kprobe->fault_handler) {
	122	if (curr_kprobe->fault_handler(curr_kprobe, regs, trapnr))
	123	return 1;
	124	}
	125	return 0;
	126	}
	127
b94cce92 HN	128	struct kprobe trampoline_p = {
	129	.addr = (kprobe_opcode_t *) &kretprobe_trampoline,
	130	.pre_handler = trampoline_probe_handler,
	131	.post_handler = trampoline_post_handler
	132	};
	133
	134	struct kretprobe_instance get_free_rp_inst(struct kretprobe rp)
	135	{
	136	struct hlist_node *node;
	137	struct kretprobe_instance *ri;
	138	hlist_for_each_entry(ri, node, &rp->free_instances, uflist)
	139	return ri;
	140	return NULL;
	141	}
	142
	143	static struct kretprobe_instance get_used_rp_inst(struct kretprobe rp)
	144	{
	145	struct hlist_node *node;
	146	struct kretprobe_instance *ri;
	147	hlist_for_each_entry(ri, node, &rp->used_instances, uflist)
	148	return ri;
	149	return NULL;
	150	}
	151
	152	struct kretprobe_instance get_rp_inst(void sara)
	153	{
	154	struct hlist_head *head;
	155	struct hlist_node *node;
	156	struct task_struct *tsk;
	157	struct kretprobe_instance *ri;
	158
	159	tsk = arch_get_kprobe_task(sara);
	160	head = &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)];
	161	hlist_for_each_entry(ri, node, head, hlist) {
	162	if (ri->stack_addr == sara)
	163	return ri;
	164	}
	165	return NULL;
	166	}
	167
	168	void add_rp_inst(struct kretprobe_instance *ri)
	169	{
	170	struct task_struct *tsk;
	171	/*
	172	* Remove rp inst off the free list -
	173	* Add it back when probed function returns
	174	*/
	175	hlist_del(&ri->uflist);
	176	tsk = arch_get_kprobe_task(ri->stack_addr);
	177	/* Add rp inst onto table */
	178	INIT_HLIST_NODE(&ri->hlist);
	179	hlist_add_head(&ri->hlist,
	180	&kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)]);
	181
	182	/* Also add this rp inst to the used list. */
	183	INIT_HLIST_NODE(&ri->uflist);
	184	hlist_add_head(&ri->uflist, &ri->rp->used_instances);
	185	}
	186
	187	void recycle_rp_inst(struct kretprobe_instance *ri)
	188	{
	189	/* remove rp inst off the rprobe_inst_table */
	190	hlist_del(&ri->hlist);
	191	if (ri->rp) {
192	/* remove rp inst off the used list */
193	hlist_del(&ri->uflist);
194	/* put rp inst back onto the free list */
195	INIT_HLIST_NODE(&ri->uflist);
196	hlist_add_head(&ri->uflist, &ri->rp->free_instances);
197	} else
198	/* Unregistering */
199	kfree(ri);
200	}
201
202	struct hlist_head * kretprobe_inst_table_head(struct task_struct *tsk)
203	{
204	return &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)];
205	}
206
207	struct kretprobe_instance get_rp_inst_tsk(struct task_struct tk)
208	{
209	struct task_struct *tsk;
210	struct hlist_head *head;
211	struct hlist_node *node;
212	struct kretprobe_instance *ri;
213
214	head = &kretprobe_inst_table[hash_ptr(tk, KPROBE_HASH_BITS)];
215
216	hlist_for_each_entry(ri, node, head, hlist) {
217	tsk = arch_get_kprobe_task(ri->stack_addr);
218	if (tsk == tk)
219	return ri;
220	}
221	return NULL;
222	}
223
224	/*
225	* This function is called from do_exit or do_execv when task tk's stack is
226	* about to be recycled. Recycle any function-return probe instances
227	* associated with this task. These represent probed functions that have
228	* been called but may never return.
229	*/
230	void kprobe_flush_task(struct task_struct *tk)
231	{
0aa55e4d HN	232	unsigned long flags = 0;
	233	spin_lock_irqsave(&kprobe_lock, flags);
	234	arch_kprobe_flush_task(tk);
	235	spin_unlock_irqrestore(&kprobe_lock, flags);
b94cce92 HN	236	}
	237
	238	/*
	239	* This kprobe pre_handler is registered with every kretprobe. When probe
	240	* hits it will set up the return probe.
	241	*/
	242	static int pre_handler_kretprobe(struct kprobe p, struct pt_regs regs)
	243	{
	244	struct kretprobe *rp = container_of(p, struct kretprobe, kp);
	245
	246	/TODO: consider to only swap the RA after the last pre_handler fired /
	247	arch_prepare_kretprobe(rp, regs);
	248	return 0;
	249	}
	250
	251	static inline void free_rp_inst(struct kretprobe *rp)
	252	{
	253	struct kretprobe_instance *ri;
	254	while ((ri = get_free_rp_inst(rp)) != NULL) {
	255	hlist_del(&ri->uflist);
	256	kfree(ri);
	257	}
	258	}
	259
64f562c6 AM	260	/*
	261	* Fill in the required fields of the "manager kprobe". Replace the
	262	* earlier kprobe in the hlist with the manager kprobe
	263	*/
	264	static inline void add_aggr_kprobe(struct kprobe ap, struct kprobe p)
	265	{
	266	ap->addr = p->addr;
7e1048b1	267	memcpy(&ap->opcode, &p->opcode, sizeof(kprobe_opcode_t));
64f562c6 AM	268	memcpy(&ap->ainsn, &p->ainsn, sizeof(struct arch_specific_insn));
	269
	270	ap->pre_handler = aggr_pre_handler;
	271	ap->post_handler = aggr_post_handler;
	272	ap->fault_handler = aggr_fault_handler;
	273
	274	INIT_LIST_HEAD(&ap->list);
	275	list_add(&p->list, &ap->list);
	276
	277	INIT_HLIST_NODE(&ap->hlist);
	278	hlist_del(&p->hlist);
	279	hlist_add_head(&ap->hlist,
	280	&kprobe_table[hash_ptr(ap->addr, KPROBE_HASH_BITS)]);
	281	}
	282
	283	/*
	284	* This is the second or subsequent kprobe at the address - handle
	285	* the intricacies
	286	* TODO: Move kcalloc outside the spinlock
	287	*/
	288	static int register_aggr_kprobe(struct kprobe old_p, struct kprobe p)
	289	{
	290	int ret = 0;
	291	struct kprobe *ap;
	292
	293	if (old_p->break_handler \|\| p->break_handler) {
	294	ret = -EEXIST; /* kprobe and jprobe can't (yet) coexist */
	295	} else if (old_p->pre_handler == aggr_pre_handler) {
	296	list_add(&p->list, &old_p->list);
	297	} else {
	298	ap = kcalloc(1, sizeof(struct kprobe), GFP_ATOMIC);
	299	if (!ap)
	300	return -ENOMEM;
	301	add_aggr_kprobe(ap, old_p);
	302	list_add(&p->list, &ap->list);
	303	}
	304	return ret;
	305	}
	306
	307	/* kprobe removal house-keeping routines */
	308	static inline void cleanup_kprobe(struct kprobe *p, unsigned long flags)
	309	{
7e1048b1	310	arch_disarm_kprobe(p);
64f562c6	311	hlist_del(&p->hlist);
64f562c6 AM	312	spin_unlock_irqrestore(&kprobe_lock, flags);
	313	arch_remove_kprobe(p);
	314	}
	315
	316	static inline void cleanup_aggr_kprobe(struct kprobe *old_p,
	317	struct kprobe *p, unsigned long flags)
	318	{
	319	list_del(&p->list);
	320	if (list_empty(&old_p->list)) {
	321	cleanup_kprobe(old_p, flags);
	322	kfree(old_p);
	323	} else
	324	spin_unlock_irqrestore(&kprobe_lock, flags);
	325	}
	326
1da177e4 LT	327	int register_kprobe(struct kprobe *p)
	328	{
	329	int ret = 0;
	330	unsigned long flags = 0;
64f562c6	331	struct kprobe *old_p;
1da177e4 LT	332
	333	if ((ret = arch_prepare_kprobe(p)) != 0) {
	334	goto rm_kprobe;
	335	}
	336	spin_lock_irqsave(&kprobe_lock, flags);
64f562c6	337	old_p = get_kprobe(p->addr);
ea32c65c	338	p->nmissed = 0;
64f562c6 AM	339	if (old_p) {
64f562c6 AM	340	ret = register_aggr_kprobe(old_p, p);
1da177e4 LT	341	goto out;
1da177e4 LT	342	}
1da177e4	343
64f562c6 AM	344	arch_copy_kprobe(p);
64f562c6 AM	345	INIT_HLIST_NODE(&p->hlist);
1da177e4 LT	346	hlist_add_head(&p->hlist,
	347	&kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
	348
7e1048b1 RL	349	arch_arm_kprobe(p);
7e1048b1 RL	350
1da177e4 LT	351	out:
	352	spin_unlock_irqrestore(&kprobe_lock, flags);
	353	rm_kprobe:
	354	if (ret == -EEXIST)
	355	arch_remove_kprobe(p);
	356	return ret;
	357	}
	358
	359	void unregister_kprobe(struct kprobe *p)
	360	{
	361	unsigned long flags;
64f562c6 AM	362	struct kprobe *old_p;
64f562c6 AM	363
1da177e4	364	spin_lock_irqsave(&kprobe_lock, flags);
64f562c6 AM	365	old_p = get_kprobe(p->addr);
	366	if (old_p) {
	367	if (old_p->pre_handler == aggr_pre_handler)
	368	cleanup_aggr_kprobe(old_p, p, flags);
	369	else
	370	cleanup_kprobe(p, flags);
	371	} else
04dea5f9	372	spin_unlock_irqrestore(&kprobe_lock, flags);
1da177e4 LT	373	}
	374
	375	static struct notifier_block kprobe_exceptions_nb = {
	376	.notifier_call = kprobe_exceptions_notify,
	377	.priority = 0x7fffffff /* we need to notified first */
	378	};
	379
	380	int register_jprobe(struct jprobe *jp)
	381	{
	382	/* Todo: Verify probepoint is a function entry point */
	383	jp->kp.pre_handler = setjmp_pre_handler;
	384	jp->kp.break_handler = longjmp_break_handler;
	385
	386	return register_kprobe(&jp->kp);
	387	}
	388
	389	void unregister_jprobe(struct jprobe *jp)
	390	{
	391	unregister_kprobe(&jp->kp);
	392	}
	393
b94cce92 HN	394	#ifdef ARCH_SUPPORTS_KRETPROBES
	395
	396	int register_kretprobe(struct kretprobe *rp)
	397	{
	398	int ret = 0;
	399	struct kretprobe_instance *inst;
	400	int i;
	401
	402	rp->kp.pre_handler = pre_handler_kretprobe;
	403
	404	/* Pre-allocate memory for max kretprobe instances */
	405	if (rp->maxactive <= 0) {
	406	#ifdef CONFIG_PREEMPT
	407	rp->maxactive = max(10, 2 * NR_CPUS);
	408	#else
	409	rp->maxactive = NR_CPUS;
	410	#endif
	411	}
	412	INIT_HLIST_HEAD(&rp->used_instances);
	413	INIT_HLIST_HEAD(&rp->free_instances);
	414	for (i = 0; i < rp->maxactive; i++) {
	415	inst = kmalloc(sizeof(struct kretprobe_instance), GFP_KERNEL);
	416	if (inst == NULL) {
	417	free_rp_inst(rp);
	418	return -ENOMEM;
	419	}
	420	INIT_HLIST_NODE(&inst->uflist);
	421	hlist_add_head(&inst->uflist, &rp->free_instances);
	422	}
	423
	424	rp->nmissed = 0;
	425	/* Establish function entry probe point */
	426	if ((ret = register_kprobe(&rp->kp)) != 0)
	427	free_rp_inst(rp);
	428	return ret;
	429	}
	430
	431	#else /* ARCH_SUPPORTS_KRETPROBES */
	432
	433	int register_kretprobe(struct kretprobe *rp)
	434	{
	435	return -ENOSYS;
	436	}
	437
	438	#endif /* ARCH_SUPPORTS_KRETPROBES */
	439
	440	void unregister_kretprobe(struct kretprobe *rp)
	441	{
	442	unsigned long flags;
	443	struct kretprobe_instance *ri;
	444
	445	unregister_kprobe(&rp->kp);
	446	/* No race here */
	447	spin_lock_irqsave(&kprobe_lock, flags);
	448	free_rp_inst(rp);
	449	while ((ri = get_used_rp_inst(rp)) != NULL) {
	450	ri->rp = NULL;
	451	hlist_del(&ri->uflist);
	452	}
	453	spin_unlock_irqrestore(&kprobe_lock, flags);
	454	}
	455
1da177e4 LT	456	static int __init init_kprobes(void)
	457	{
	458	int i, err = 0;
	459
	460	/* FIXME allocate the probe table, currently defined statically */
	461	/* initialize all list heads */
b94cce92	462	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1da177e4	463	INIT_HLIST_HEAD(&kprobe_table[i]);
b94cce92 HN	464	INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
b94cce92 HN	465	}
1da177e4 LT	466
1da177e4 LT	467	err = register_die_notifier(&kprobe_exceptions_nb);
b94cce92 HN	468	/* Register the trampoline probe for return probe */
b94cce92 HN	469	register_kprobe(&trampoline_p);
1da177e4 LT	470	return err;
	471	}
	472
	473	__initcall(init_kprobes);
	474
	475	EXPORT_SYMBOL_GPL(register_kprobe);
	476	EXPORT_SYMBOL_GPL(unregister_kprobe);
	477	EXPORT_SYMBOL_GPL(register_jprobe);
	478	EXPORT_SYMBOL_GPL(unregister_jprobe);
	479	EXPORT_SYMBOL_GPL(jprobe_return);
b94cce92 HN	480	EXPORT_SYMBOL_GPL(register_kretprobe);
	481	EXPORT_SYMBOL_GPL(unregister_kretprobe);
	482