sysklogd/oops.c

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/*
oops.c - Dummy loadable module for testing klogd.
Copyright (c) 2007 Martin Schulze <joey@infodrom.org>
This file is part of the sysklogd package, a kernel and system log daemon.
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., 675 Mass Ave, Cambridge, MA 02139, USA.
Helpful documentation: http://www.tldp.org/LDP/lkmpg/2.6/html/
SYNOPSIS
echo TEXT > /proc/oops Emits TEXT via printk at log level
[<address+delta>] triggers klogd address decoding
echo level: info > /proc/oops Sets the log level to 'info'
echo oops > /proc/oops Creates a real oops, kills executing shell
cat /proc/oops Display current log level and last oops time
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/poll.h>
#include <linux/time.h>
#define MODNAME "oops"
#define PROCNAME "oops"
MODULE_AUTHOR("Martin Schulze <joey@infodrom.org>");
MODULE_DESCRIPTION("Oops module from klogd");
MODULE_LICENSE("GPL");
static DEFINE_MUTEX(oops_lock);
struct oops_t {
unsigned long lastoops;
int loglevel;
};
static struct oops_t oops_data;
static int procflag = 0;
struct code {
char *name;
int level;
};
struct code priorities[] = {
{"emerg", 0},
{"panic", 0}, /* DEPRECATED */
{"alert", 1},
{"crit", 2},
{"err", 3},
{"error", 3}, /* DEPRECATED */
{"warning", 4},
{"warn", 4}, /* DEPRECATED */
{"notice", 5},
{"info", 6},
{"debug", 7},
{NULL, -1}
};
void oops_decode_level (char *line)
{
char *p;
struct code *prio;
if (strncmp(line, "level:", 6))
return;
for (p = (char *)(line) + 6;*p == ' ' || *p == '\t';p++);
for (prio = priorities; prio->name; prio++)
if (!strcmp(p, prio->name)) {
oops_data.loglevel = prio->level;
return;
}
}
/*
* This routine will create a real and ugly oops
*/
static void oops(void)
{
auto unsigned long *p = (unsigned long *) 828282828;
*p = 5;
return;
}
static int oops_proc_open (struct inode *inode, struct file *file)
{
#ifdef DEBUG
printk (KERN_DEBUG "oops_proc_open().\n");
#endif
return 0;
}
static ssize_t
oops_proc_read (struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
{
char s[70];
int size;
struct code *prio;
char *level = NULL;
#ifdef DEBUG
printk (KERN_DEBUG "oops_proc_read(%d).\n",nbytes);
#endif
if (procflag) {
procflag = 0;
return 0;
}
for (prio = priorities;
prio->name && prio->level != oops_data.loglevel;
prio++);
level = prio->name;
if (oops_data.lastoops == 0)
size = sprintf (s, "Log level: %s\nLast oops: none\n", level);
else {
unsigned long now = get_seconds();
unsigned long delta = now - oops_data.lastoops;
size = sprintf (s, "Log level: %s\nLast oops: %lu (%lu second%s ago)\n",
level, oops_data.lastoops,
delta, delta == 1 ? "" : "s");
}
if (size < nbytes)
nbytes = size;
if (copy_to_user(buf, s, nbytes))
return -EFAULT;
*ppos += nbytes;
procflag++;
return nbytes;
}
static int
oops_proc_release(struct inode *inode, struct file *filp)
{
#ifdef DEBUG
printk (KERN_DEBUG "oops_proc_release().\n");
#endif
return 0;
}
static ssize_t
oops_proc_write(struct file *file, const char __user *buf,
size_t nbytes, loff_t *ppos)
{
char input[100];
int len;
#ifdef DEBUG
printk (KERN_DEBUG "oops_proc_write(%d).\n", nbytes);
#endif
len = nbytes >= sizeof(input) ? sizeof(input)-1 : nbytes;
if (copy_from_user(input, buf, len))
return -EFAULT;
input[len] = '\0';
if (input[len-1] == '\n')
input[len-1] = '\0';
if (!strncmp(input, "level:", 6))
oops_decode_level(input);
else if (!strcmp(input, "oops")) {
oops_data.lastoops = get_seconds();
oops();
} else
printk ("<%d>%s\n", oops_data.loglevel, input);
return nbytes;
}
static const struct file_operations oops_proc_operations = {
.read = oops_proc_read,
.release = oops_proc_release,
.write = oops_proc_write,
.open = oops_proc_open,
};
void oops_proc_add (void)
{
struct proc_dir_entry *entry;
mutex_lock (&oops_lock);
entry = create_proc_entry (PROCNAME, 0, NULL);
if (entry) {
entry->proc_fops = &oops_proc_operations;
}
mutex_unlock (&oops_lock);
}
void oops_proc_remove (void)
{
mutex_lock (&oops_lock);
remove_proc_entry(PROCNAME, NULL);
mutex_unlock(&oops_lock);
}
int oops_init (void)
{
printk (KERN_INFO "Loading module " MODNAME ".\n");
oops_data.lastoops = 0;
oops_data.loglevel = 5;
oops_proc_add();
return 0;
}
void oops_cleanup (void)
{
oops_proc_remove();
printk (KERN_INFO "Removing module " MODNAME ".\n");
}
module_init(oops_init);
module_exit(oops_cleanup);