cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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indydog.c (4523B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 *	IndyDog	0.3	A Hardware Watchdog Device for SGI IP22
      4 *
      5 *	(c) Copyright 2002 Guido Guenther <agx@sigxcpu.org>,
      6 *						All Rights Reserved.
      7 *
      8 *	based on softdog.c by Alan Cox <alan@lxorguk.ukuu.org.uk>
      9 */
     10
     11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
     12
     13#include <linux/module.h>
     14#include <linux/moduleparam.h>
     15#include <linux/types.h>
     16#include <linux/kernel.h>
     17#include <linux/fs.h>
     18#include <linux/mm.h>
     19#include <linux/miscdevice.h>
     20#include <linux/watchdog.h>
     21#include <linux/notifier.h>
     22#include <linux/reboot.h>
     23#include <linux/init.h>
     24#include <linux/uaccess.h>
     25#include <asm/sgi/mc.h>
     26
     27static unsigned long indydog_alive;
     28static DEFINE_SPINLOCK(indydog_lock);
     29
     30#define WATCHDOG_TIMEOUT 30		/* 30 sec default timeout */
     31
     32static bool nowayout = WATCHDOG_NOWAYOUT;
     33module_param(nowayout, bool, 0);
     34MODULE_PARM_DESC(nowayout,
     35		"Watchdog cannot be stopped once started (default="
     36				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
     37
     38static void indydog_start(void)
     39{
     40	spin_lock(&indydog_lock);
     41	sgimc->cpuctrl0 |= SGIMC_CCTRL0_WDOG;
     42	spin_unlock(&indydog_lock);
     43}
     44
     45static void indydog_stop(void)
     46{
     47	spin_lock(&indydog_lock);
     48	sgimc->cpuctrl0 &= ~SGIMC_CCTRL0_WDOG;
     49	spin_unlock(&indydog_lock);
     50
     51	pr_info("Stopped watchdog timer\n");
     52}
     53
     54static void indydog_ping(void)
     55{
     56	sgimc->watchdogt = 0;
     57}
     58
     59/*
     60 *	Allow only one person to hold it open
     61 */
     62static int indydog_open(struct inode *inode, struct file *file)
     63{
     64	if (test_and_set_bit(0, &indydog_alive))
     65		return -EBUSY;
     66
     67	if (nowayout)
     68		__module_get(THIS_MODULE);
     69
     70	/* Activate timer */
     71	indydog_start();
     72	indydog_ping();
     73
     74	pr_info("Started watchdog timer\n");
     75
     76	return stream_open(inode, file);
     77}
     78
     79static int indydog_release(struct inode *inode, struct file *file)
     80{
     81	/* Shut off the timer.
     82	 * Lock it in if it's a module and we defined ...NOWAYOUT */
     83	if (!nowayout)
     84		indydog_stop();		/* Turn the WDT off */
     85	clear_bit(0, &indydog_alive);
     86	return 0;
     87}
     88
     89static ssize_t indydog_write(struct file *file, const char *data,
     90						size_t len, loff_t *ppos)
     91{
     92	/* Refresh the timer. */
     93	if (len)
     94		indydog_ping();
     95	return len;
     96}
     97
     98static long indydog_ioctl(struct file *file, unsigned int cmd,
     99							unsigned long arg)
    100{
    101	int options, retval = -EINVAL;
    102	static const struct watchdog_info ident = {
    103		.options		= WDIOF_KEEPALIVEPING,
    104		.firmware_version	= 0,
    105		.identity		= "Hardware Watchdog for SGI IP22",
    106	};
    107
    108	switch (cmd) {
    109	case WDIOC_GETSUPPORT:
    110		if (copy_to_user((struct watchdog_info *)arg,
    111				 &ident, sizeof(ident)))
    112			return -EFAULT;
    113		return 0;
    114	case WDIOC_GETSTATUS:
    115	case WDIOC_GETBOOTSTATUS:
    116		return put_user(0, (int *)arg);
    117	case WDIOC_SETOPTIONS:
    118	{
    119		if (get_user(options, (int *)arg))
    120			return -EFAULT;
    121		if (options & WDIOS_DISABLECARD) {
    122			indydog_stop();
    123			retval = 0;
    124		}
    125		if (options & WDIOS_ENABLECARD) {
    126			indydog_start();
    127			retval = 0;
    128		}
    129		return retval;
    130	}
    131	case WDIOC_KEEPALIVE:
    132		indydog_ping();
    133		return 0;
    134	case WDIOC_GETTIMEOUT:
    135		return put_user(WATCHDOG_TIMEOUT, (int *)arg);
    136	default:
    137		return -ENOTTY;
    138	}
    139}
    140
    141static int indydog_notify_sys(struct notifier_block *this,
    142					unsigned long code, void *unused)
    143{
    144	if (code == SYS_DOWN || code == SYS_HALT)
    145		indydog_stop();		/* Turn the WDT off */
    146
    147	return NOTIFY_DONE;
    148}
    149
    150static const struct file_operations indydog_fops = {
    151	.owner		= THIS_MODULE,
    152	.llseek		= no_llseek,
    153	.write		= indydog_write,
    154	.unlocked_ioctl	= indydog_ioctl,
    155	.compat_ioctl	= compat_ptr_ioctl,
    156	.open		= indydog_open,
    157	.release	= indydog_release,
    158};
    159
    160static struct miscdevice indydog_miscdev = {
    161	.minor		= WATCHDOG_MINOR,
    162	.name		= "watchdog",
    163	.fops		= &indydog_fops,
    164};
    165
    166static struct notifier_block indydog_notifier = {
    167	.notifier_call = indydog_notify_sys,
    168};
    169
    170static int __init watchdog_init(void)
    171{
    172	int ret;
    173
    174	ret = register_reboot_notifier(&indydog_notifier);
    175	if (ret) {
    176		pr_err("cannot register reboot notifier (err=%d)\n", ret);
    177		return ret;
    178	}
    179
    180	ret = misc_register(&indydog_miscdev);
    181	if (ret) {
    182		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
    183		       WATCHDOG_MINOR, ret);
    184		unregister_reboot_notifier(&indydog_notifier);
    185		return ret;
    186	}
    187
    188	pr_info("Hardware Watchdog Timer for SGI IP22: 0.3\n");
    189
    190	return 0;
    191}
    192
    193static void __exit watchdog_exit(void)
    194{
    195	misc_deregister(&indydog_miscdev);
    196	unregister_reboot_notifier(&indydog_notifier);
    197}
    198
    199module_init(watchdog_init);
    200module_exit(watchdog_exit);
    201
    202MODULE_AUTHOR("Guido Guenther <agx@sigxcpu.org>");
    203MODULE_DESCRIPTION("Hardware Watchdog Device for SGI IP22");
    204MODULE_LICENSE("GPL");