kernel26-2.6.12-alx-r9/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.
 */
#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];

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
 */
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;
}

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;
}

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;
}

/*
 * 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;
	ap->opcode = p->opcode;
	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)
{
	*p->addr = p->opcode;
	hlist_del(&p->hlist);
	flush_icache_range((unsigned long) p->addr,
		   (unsigned long) p->addr + sizeof(kprobe_opcode_t));
	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);
	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)]);

	p->opcode = *p->addr;
	*p->addr = BREAKPOINT_INSTRUCTION;
	flush_icache_range((unsigned long) p->addr,
			   (unsigned long) p->addr + sizeof(kprobe_opcode_t));
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);
}

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]);

	err = register_die_notifier(&kprobe_exceptions_nb);
	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);
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.
30	*/
31	#include <linux/kprobes.h>
32	#include <linux/spinlock.h>
33	#include <linux/hash.h>
34	#include <linux/init.h>
35	#include <linux/module.h>
36	#include <asm/cacheflush.h>
37	#include <asm/errno.h>
38	#include <asm/kdebug.h>
39
40	#define KPROBE_HASH_BITS 6
41	#define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
42
43	static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
44
45	unsigned int kprobe_cpu = NR_CPUS;
46	static DEFINE_SPINLOCK(kprobe_lock);
47	static struct kprobe *curr_kprobe;
48
49	/* Locks kprobe: irqs must be disabled */
50	void lock_kprobes(void)
51	{
52	spin_lock(&kprobe_lock);
53	kprobe_cpu = smp_processor_id();
54	}
55
56	void unlock_kprobes(void)
57	{
58	kprobe_cpu = NR_CPUS;
59	spin_unlock(&kprobe_lock);
60	}
61
62	/* You have to be holding the kprobe_lock */
63	struct kprobe get_kprobe(void addr)
64	{
65	struct hlist_head *head;
66	struct hlist_node *node;
67
68	head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
69	hlist_for_each(node, head) {
70	struct kprobe *p = hlist_entry(node, struct kprobe, hlist);
71	if (p->addr == addr)
72	return p;
73	}
74	return NULL;
75	}
76
77	/*
78	* Aggregate handlers for multiple kprobes support - these handlers
79	* take care of invoking the individual kprobe handlers on p->list
80	*/
81	int aggr_pre_handler(struct kprobe p, struct pt_regs regs)
82	{
83	struct kprobe *kp;
84
85	list_for_each_entry(kp, &p->list, list) {
86	if (kp->pre_handler) {
87	curr_kprobe = kp;
88	kp->pre_handler(kp, regs);
89	curr_kprobe = NULL;
90	}
91	}
92	return 0;
93	}
94
95	void aggr_post_handler(struct kprobe p, struct pt_regs regs,
96	unsigned long flags)
97	{
98	struct kprobe *kp;
99
100	list_for_each_entry(kp, &p->list, list) {
101	if (kp->post_handler) {
102	curr_kprobe = kp;
103	kp->post_handler(kp, regs, flags);
104	curr_kprobe = NULL;
105	}
106	}
107	return;
108	}
109
110	int aggr_fault_handler(struct kprobe p, struct pt_regs regs, int trapnr)
111	{
112	/*
113	* if we faulted "during" the execution of a user specified
114	* probe handler, invoke just that probe's fault handler
115	*/
116	if (curr_kprobe && curr_kprobe->fault_handler) {
117	if (curr_kprobe->fault_handler(curr_kprobe, regs, trapnr))
118	return 1;
119	}
120	return 0;
121	}
122
123	/*
124	* Fill in the required fields of the "manager kprobe". Replace the
125	* earlier kprobe in the hlist with the manager kprobe
126	*/
127	static inline void add_aggr_kprobe(struct kprobe ap, struct kprobe p)
128	{
129	ap->addr = p->addr;
130	ap->opcode = p->opcode;
131	memcpy(&ap->ainsn, &p->ainsn, sizeof(struct arch_specific_insn));
132
133	ap->pre_handler = aggr_pre_handler;
134	ap->post_handler = aggr_post_handler;
135	ap->fault_handler = aggr_fault_handler;
136
137	INIT_LIST_HEAD(&ap->list);
138	list_add(&p->list, &ap->list);
139
140	INIT_HLIST_NODE(&ap->hlist);
141	hlist_del(&p->hlist);
142	hlist_add_head(&ap->hlist,
143	&kprobe_table[hash_ptr(ap->addr, KPROBE_HASH_BITS)]);
144	}
145
146	/*
147	* This is the second or subsequent kprobe at the address - handle
148	* the intricacies
149	* TODO: Move kcalloc outside the spinlock
150	*/
151	static int register_aggr_kprobe(struct kprobe old_p, struct kprobe p)
152	{
153	int ret = 0;
154	struct kprobe *ap;
155
156	if (old_p->break_handler \|\| p->break_handler) {
157	ret = -EEXIST; /* kprobe and jprobe can't (yet) coexist */
158	} else if (old_p->pre_handler == aggr_pre_handler) {
159	list_add(&p->list, &old_p->list);
160	} else {
161	ap = kcalloc(1, sizeof(struct kprobe), GFP_ATOMIC);
162	if (!ap)
163	return -ENOMEM;
164	add_aggr_kprobe(ap, old_p);
165	list_add(&p->list, &ap->list);
166	}
167	return ret;
168	}
169
170	/* kprobe removal house-keeping routines */
171	static inline void cleanup_kprobe(struct kprobe *p, unsigned long flags)
172	{
173	*p->addr = p->opcode;
174	hlist_del(&p->hlist);
175	flush_icache_range((unsigned long) p->addr,
176	(unsigned long) p->addr + sizeof(kprobe_opcode_t));
177	spin_unlock_irqrestore(&kprobe_lock, flags);
178	arch_remove_kprobe(p);
179	}
180
181	static inline void cleanup_aggr_kprobe(struct kprobe *old_p,
182	struct kprobe *p, unsigned long flags)
183	{
184	list_del(&p->list);
185	if (list_empty(&old_p->list)) {
186	cleanup_kprobe(old_p, flags);
187	kfree(old_p);
188	} else
189	spin_unlock_irqrestore(&kprobe_lock, flags);
190	}
191
192	int register_kprobe(struct kprobe *p)
193	{
194	int ret = 0;
195	unsigned long flags = 0;
196	struct kprobe *old_p;
197
198	if ((ret = arch_prepare_kprobe(p)) != 0) {
199	goto rm_kprobe;
200	}
201	spin_lock_irqsave(&kprobe_lock, flags);
202	old_p = get_kprobe(p->addr);
203	if (old_p) {
204	ret = register_aggr_kprobe(old_p, p);
205	goto out;
206	}
207
208	arch_copy_kprobe(p);
209	INIT_HLIST_NODE(&p->hlist);
210	hlist_add_head(&p->hlist,
211	&kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
212
213	p->opcode = *p->addr;
214	*p->addr = BREAKPOINT_INSTRUCTION;
215	flush_icache_range((unsigned long) p->addr,
216	(unsigned long) p->addr + sizeof(kprobe_opcode_t));
217	out:
218	spin_unlock_irqrestore(&kprobe_lock, flags);
219	rm_kprobe:
220	if (ret == -EEXIST)
221	arch_remove_kprobe(p);
222	return ret;
223	}
224
225	void unregister_kprobe(struct kprobe *p)
226	{
227	unsigned long flags;
228	struct kprobe *old_p;
229
230	spin_lock_irqsave(&kprobe_lock, flags);
231	old_p = get_kprobe(p->addr);
232	if (old_p) {
233	if (old_p->pre_handler == aggr_pre_handler)
234	cleanup_aggr_kprobe(old_p, p, flags);
235	else
236	cleanup_kprobe(p, flags);
237	} else
238	spin_unlock_irqrestore(&kprobe_lock, flags);
239	}
240
241	static struct notifier_block kprobe_exceptions_nb = {
242	.notifier_call = kprobe_exceptions_notify,
243	.priority = 0x7fffffff /* we need to notified first */
244	};
245
246	int register_jprobe(struct jprobe *jp)
247	{
248	/* Todo: Verify probepoint is a function entry point */
249	jp->kp.pre_handler = setjmp_pre_handler;
250	jp->kp.break_handler = longjmp_break_handler;
251
252	return register_kprobe(&jp->kp);
253	}
254
255	void unregister_jprobe(struct jprobe *jp)
256	{
257	unregister_kprobe(&jp->kp);
258	}
259
260	static int __init init_kprobes(void)
261	{
262	int i, err = 0;
263
264	/* FIXME allocate the probe table, currently defined statically */
265	/* initialize all list heads */
266	for (i = 0; i < KPROBE_TABLE_SIZE; i++)
267	INIT_HLIST_HEAD(&kprobe_table[i]);
268
269	err = register_die_notifier(&kprobe_exceptions_nb);
270	return err;
271	}
272
273	__initcall(init_kprobes);
274
275	EXPORT_SYMBOL_GPL(register_kprobe);
276	EXPORT_SYMBOL_GPL(unregister_kprobe);
277	EXPORT_SYMBOL_GPL(register_jprobe);
278	EXPORT_SYMBOL_GPL(unregister_jprobe);
279	EXPORT_SYMBOL_GPL(jprobe_return);