cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

harddog_kern.c (4217B)

      1/* UML hardware watchdog, shamelessly stolen from:
      2 *
      3 *	SoftDog	0.05:	A Software Watchdog Device
      4 *
      5 *	(c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
      6 *				http://www.redhat.com
      7 *
      8 *	This program is free software; you can redistribute it and/or
      9 *	modify it under the terms of the GNU General Public License
     10 *	as published by the Free Software Foundation; either version
     11 *	2 of the License, or (at your option) any later version.
     12 *
     13 *	Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
     14 *	warranty for any of this software. This material is provided
     15 *	"AS-IS" and at no charge.
     16 *
     17 *	(c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
     18 *
     19 *	Software only watchdog driver. Unlike its big brother the WDT501P
     20 *	driver this won't always recover a failed machine.
     21 *
     22 *  03/96: Angelo Haritsis <ah@doc.ic.ac.uk> :
     23 *	Modularised.
     24 *	Added soft_margin; use upon insmod to change the timer delay.
     25 *	NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate
     26 *	    minors.
     27 *
     28 *  19980911 Alan Cox
     29 *	Made SMP safe for 2.3.x
     30 *
     31 *  20011127 Joel Becker (jlbec@evilplan.org>
     32 *	Added soft_noboot; Allows testing the softdog trigger without
     33 *	requiring a recompile.
     34 *	Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT.
     35 */
     36
     37#include <linux/module.h>
     38#include <linux/types.h>
     39#include <linux/kernel.h>
     40#include <linux/fs.h>
     41#include <linux/mm.h>
     42#include <linux/miscdevice.h>
     43#include <linux/watchdog.h>
     44#include <linux/reboot.h>
     45#include <linux/mutex.h>
     46#include <linux/init.h>
     47#include <linux/spinlock.h>
     48#include <linux/uaccess.h>
     49#include "mconsole.h"
     50
     51MODULE_LICENSE("GPL");
     52
     53static DEFINE_MUTEX(harddog_mutex);
     54static DEFINE_SPINLOCK(lock);
     55static int timer_alive;
     56static int harddog_in_fd = -1;
     57static int harddog_out_fd = -1;
     58
     59/*
     60 *	Allow only one person to hold it open
     61 */
     62
     63extern int start_watchdog(int *in_fd_ret, int *out_fd_ret, char *sock);
     64
     65static int harddog_open(struct inode *inode, struct file *file)
     66{
     67	int err = -EBUSY;
     68	char *sock = NULL;
     69
     70	mutex_lock(&harddog_mutex);
     71	spin_lock(&lock);
     72	if(timer_alive)
     73		goto err;
     74#ifdef CONFIG_WATCHDOG_NOWAYOUT
     75	__module_get(THIS_MODULE);
     76#endif
     77
     78#ifdef CONFIG_MCONSOLE
     79	sock = mconsole_notify_socket();
     80#endif
     81	err = start_watchdog(&harddog_in_fd, &harddog_out_fd, sock);
     82	if(err)
     83		goto err;
     84
     85	timer_alive = 1;
     86	spin_unlock(&lock);
     87	mutex_unlock(&harddog_mutex);
     88	return stream_open(inode, file);
     89err:
     90	spin_unlock(&lock);
     91	mutex_unlock(&harddog_mutex);
     92	return err;
     93}
     94
     95extern void stop_watchdog(int in_fd, int out_fd);
     96
     97static int harddog_release(struct inode *inode, struct file *file)
     98{
     99	/*
    100	 *	Shut off the timer.
    101	 */
    102
    103	spin_lock(&lock);
    104
    105	stop_watchdog(harddog_in_fd, harddog_out_fd);
    106	harddog_in_fd = -1;
    107	harddog_out_fd = -1;
    108
    109	timer_alive=0;
    110	spin_unlock(&lock);
    111
    112	return 0;
    113}
    114
    115extern int ping_watchdog(int fd);
    116
    117static ssize_t harddog_write(struct file *file, const char __user *data, size_t len,
    118			     loff_t *ppos)
    119{
    120	/*
    121	 *	Refresh the timer.
    122	 */
    123	if(len)
    124		return ping_watchdog(harddog_out_fd);
    125	return 0;
    126}
    127
    128static int harddog_ioctl_unlocked(struct file *file,
    129				  unsigned int cmd, unsigned long arg)
    130{
    131	void __user *argp= (void __user *)arg;
    132	static struct watchdog_info ident = {
    133		WDIOC_SETTIMEOUT,
    134		0,
    135		"UML Hardware Watchdog"
    136	};
    137	switch (cmd) {
    138		default:
    139			return -ENOTTY;
    140		case WDIOC_GETSUPPORT:
    141			if(copy_to_user(argp, &ident, sizeof(ident)))
    142				return -EFAULT;
    143			return 0;
    144		case WDIOC_GETSTATUS:
    145		case WDIOC_GETBOOTSTATUS:
    146			return put_user(0,(int __user *)argp);
    147		case WDIOC_KEEPALIVE:
    148			return ping_watchdog(harddog_out_fd);
    149	}
    150}
    151
    152static long harddog_ioctl(struct file *file,
    153			  unsigned int cmd, unsigned long arg)
    154{
    155	long ret;
    156
    157	mutex_lock(&harddog_mutex);
    158	ret = harddog_ioctl_unlocked(file, cmd, arg);
    159	mutex_unlock(&harddog_mutex);
    160
    161	return ret;
    162}
    163
    164static const struct file_operations harddog_fops = {
    165	.owner		= THIS_MODULE,
    166	.write		= harddog_write,
    167	.unlocked_ioctl	= harddog_ioctl,
    168	.compat_ioctl	= compat_ptr_ioctl,
    169	.open		= harddog_open,
    170	.release	= harddog_release,
    171	.llseek		= no_llseek,
    172};
    173
    174static struct miscdevice harddog_miscdev = {
    175	.minor		= WATCHDOG_MINOR,
    176	.name		= "watchdog",
    177	.fops		= &harddog_fops,
    178};
    179module_misc_device(harddog_miscdev);