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/*
* 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);
/* 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;
}
int register_kprobe(struct kprobe *p)
{
int ret = 0;
unsigned long flags = 0;
if ((ret = arch_prepare_kprobe(p)) != 0) {
goto rm_kprobe;
}
spin_lock_irqsave(&kprobe_lock, flags);
INIT_HLIST_NODE(&p->hlist);
if (get_kprobe(p->addr)) {
ret = -EEXIST;
goto out;
}
arch_copy_kprobe(p);
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;
spin_lock_irqsave(&kprobe_lock, flags);
if (!get_kprobe(p->addr)) {
spin_unlock_irqrestore(&kprobe_lock, flags);
return;
}
*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 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);
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