linux/drivers/watchdog/cpu5wdt.c
David Howells 5d1c93ce21 Annotate hardware config module parameters in drivers/watchdog/
When the kernel is running in secure boot mode, we lock down the kernel to
prevent userspace from modifying the running kernel image.  Whilst this
includes prohibiting access to things like /dev/mem, it must also prevent
access by means of configuring driver modules in such a way as to cause a
device to access or modify the kernel image.

To this end, annotate module_param* statements that refer to hardware
configuration and indicate for future reference what type of parameter they
specify.  The parameter parser in the core sees this information and can
skip such parameters with an error message if the kernel is locked down.
The module initialisation then runs as normal, but just sees whatever the
default values for those parameters is.

Note that we do still need to do the module initialisation because some
drivers have viable defaults set in case parameters aren't specified and
some drivers support automatic configuration (e.g. PNP or PCI) in addition
to manually coded parameters.

This patch annotates drivers in drivers/watchdog/.

Suggested-by: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
cc: Wim Van Sebroeck <wim@iguana.be>
cc: Zwane Mwaikambo <zwanem@gmail.com>
cc: linux-watchdog@vger.kernel.org
2017-04-20 12:02:32 +01:00

300 lines
6.6 KiB
C

/*
* sma cpu5 watchdog driver
*
* Copyright (C) 2003 Heiko Ronsdorf <hero@ihg.uni-duisburg.de>
*
* 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.
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/fs.h>
#include <linux/ioport.h>
#include <linux/timer.h>
#include <linux/completion.h>
#include <linux/jiffies.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/watchdog.h>
/* adjustable parameters */
static int verbose;
static int port = 0x91;
static int ticks = 10000;
static DEFINE_SPINLOCK(cpu5wdt_lock);
#define PFX "cpu5wdt: "
#define CPU5WDT_EXTENT 0x0A
#define CPU5WDT_STATUS_REG 0x00
#define CPU5WDT_TIME_A_REG 0x02
#define CPU5WDT_TIME_B_REG 0x03
#define CPU5WDT_MODE_REG 0x04
#define CPU5WDT_TRIGGER_REG 0x07
#define CPU5WDT_ENABLE_REG 0x08
#define CPU5WDT_RESET_REG 0x09
#define CPU5WDT_INTERVAL (HZ/10+1)
/* some device data */
static struct {
struct completion stop;
int running;
struct timer_list timer;
int queue;
int default_ticks;
unsigned long inuse;
} cpu5wdt_device;
/* generic helper functions */
static void cpu5wdt_trigger(unsigned long unused)
{
if (verbose > 2)
pr_debug("trigger at %i ticks\n", ticks);
if (cpu5wdt_device.running)
ticks--;
spin_lock(&cpu5wdt_lock);
/* keep watchdog alive */
outb(1, port + CPU5WDT_TRIGGER_REG);
/* requeue?? */
if (cpu5wdt_device.queue && ticks)
mod_timer(&cpu5wdt_device.timer, jiffies + CPU5WDT_INTERVAL);
else {
/* ticks doesn't matter anyway */
complete(&cpu5wdt_device.stop);
}
spin_unlock(&cpu5wdt_lock);
}
static void cpu5wdt_reset(void)
{
ticks = cpu5wdt_device.default_ticks;
if (verbose)
pr_debug("reset (%i ticks)\n", (int) ticks);
}
static void cpu5wdt_start(void)
{
unsigned long flags;
spin_lock_irqsave(&cpu5wdt_lock, flags);
if (!cpu5wdt_device.queue) {
cpu5wdt_device.queue = 1;
outb(0, port + CPU5WDT_TIME_A_REG);
outb(0, port + CPU5WDT_TIME_B_REG);
outb(1, port + CPU5WDT_MODE_REG);
outb(0, port + CPU5WDT_RESET_REG);
outb(0, port + CPU5WDT_ENABLE_REG);
mod_timer(&cpu5wdt_device.timer, jiffies + CPU5WDT_INTERVAL);
}
/* if process dies, counter is not decremented */
cpu5wdt_device.running++;
spin_unlock_irqrestore(&cpu5wdt_lock, flags);
}
static int cpu5wdt_stop(void)
{
unsigned long flags;
spin_lock_irqsave(&cpu5wdt_lock, flags);
if (cpu5wdt_device.running)
cpu5wdt_device.running = 0;
ticks = cpu5wdt_device.default_ticks;
spin_unlock_irqrestore(&cpu5wdt_lock, flags);
if (verbose)
pr_crit("stop not possible\n");
return -EIO;
}
/* filesystem operations */
static int cpu5wdt_open(struct inode *inode, struct file *file)
{
if (test_and_set_bit(0, &cpu5wdt_device.inuse))
return -EBUSY;
return nonseekable_open(inode, file);
}
static int cpu5wdt_release(struct inode *inode, struct file *file)
{
clear_bit(0, &cpu5wdt_device.inuse);
return 0;
}
static long cpu5wdt_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
void __user *argp = (void __user *)arg;
int __user *p = argp;
unsigned int value;
static const struct watchdog_info ident = {
.options = WDIOF_CARDRESET,
.identity = "CPU5 WDT",
};
switch (cmd) {
case WDIOC_GETSUPPORT:
if (copy_to_user(argp, &ident, sizeof(ident)))
return -EFAULT;
break;
case WDIOC_GETSTATUS:
value = inb(port + CPU5WDT_STATUS_REG);
value = (value >> 2) & 1;
return put_user(value, p);
case WDIOC_GETBOOTSTATUS:
return put_user(0, p);
case WDIOC_SETOPTIONS:
if (get_user(value, p))
return -EFAULT;
if (value & WDIOS_ENABLECARD)
cpu5wdt_start();
if (value & WDIOS_DISABLECARD)
cpu5wdt_stop();
break;
case WDIOC_KEEPALIVE:
cpu5wdt_reset();
break;
default:
return -ENOTTY;
}
return 0;
}
static ssize_t cpu5wdt_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
if (!count)
return -EIO;
cpu5wdt_reset();
return count;
}
static const struct file_operations cpu5wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.unlocked_ioctl = cpu5wdt_ioctl,
.open = cpu5wdt_open,
.write = cpu5wdt_write,
.release = cpu5wdt_release,
};
static struct miscdevice cpu5wdt_misc = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &cpu5wdt_fops,
};
/* init/exit function */
static int cpu5wdt_init(void)
{
unsigned int val;
int err;
if (verbose)
pr_debug("port=0x%x, verbose=%i\n", port, verbose);
init_completion(&cpu5wdt_device.stop);
cpu5wdt_device.queue = 0;
setup_timer(&cpu5wdt_device.timer, cpu5wdt_trigger, 0);
cpu5wdt_device.default_ticks = ticks;
if (!request_region(port, CPU5WDT_EXTENT, PFX)) {
pr_err("request_region failed\n");
err = -EBUSY;
goto no_port;
}
/* watchdog reboot? */
val = inb(port + CPU5WDT_STATUS_REG);
val = (val >> 2) & 1;
if (!val)
pr_info("sorry, was my fault\n");
err = misc_register(&cpu5wdt_misc);
if (err < 0) {
pr_err("misc_register failed\n");
goto no_misc;
}
pr_info("init success\n");
return 0;
no_misc:
release_region(port, CPU5WDT_EXTENT);
no_port:
return err;
}
static int cpu5wdt_init_module(void)
{
return cpu5wdt_init();
}
static void cpu5wdt_exit(void)
{
if (cpu5wdt_device.queue) {
cpu5wdt_device.queue = 0;
wait_for_completion(&cpu5wdt_device.stop);
del_timer(&cpu5wdt_device.timer);
}
misc_deregister(&cpu5wdt_misc);
release_region(port, CPU5WDT_EXTENT);
}
static void cpu5wdt_exit_module(void)
{
cpu5wdt_exit();
}
/* module entry points */
module_init(cpu5wdt_init_module);
module_exit(cpu5wdt_exit_module);
MODULE_AUTHOR("Heiko Ronsdorf <hero@ihg.uni-duisburg.de>");
MODULE_DESCRIPTION("sma cpu5 watchdog driver");
MODULE_SUPPORTED_DEVICE("sma cpu5 watchdog");
MODULE_LICENSE("GPL");
module_param_hw(port, int, ioport, 0);
MODULE_PARM_DESC(port, "base address of watchdog card, default is 0x91");
module_param(verbose, int, 0);
MODULE_PARM_DESC(verbose, "be verbose, default is 0 (no)");
module_param(ticks, int, 0);
MODULE_PARM_DESC(ticks, "count down ticks, default is 10000");