![David Howells](/assets/img/avatar_default.png)
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
480 lines
11 KiB
C
480 lines
11 KiB
C
/*
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* National Semiconductor PC87307/PC97307 (ala SC1200) WDT driver
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* (c) Copyright 2002 Zwane Mwaikambo <zwane@commfireservices.com>,
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* All Rights Reserved.
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* Based on wdt.c and wdt977.c by Alan Cox and Woody Suwalski respectively.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* The author(s) of this software shall not be held liable for damages
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* of any nature resulting due to the use of this software. This
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* software is provided AS-IS with no warranties.
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*
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* Changelog:
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* 20020220 Zwane Mwaikambo Code based on datasheet, no hardware.
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* 20020221 Zwane Mwaikambo Cleanups as suggested by Jeff Garzik
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* and Alan Cox.
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* 20020222 Zwane Mwaikambo Added probing.
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* 20020225 Zwane Mwaikambo Added ISAPNP support.
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* 20020412 Rob Radez Broke out start/stop functions
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* <rob@osinvestor.com> Return proper status instead of
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* temperature warning
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* Add WDIOC_GETBOOTSTATUS and
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* WDIOC_SETOPTIONS ioctls
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* Fix CONFIG_WATCHDOG_NOWAYOUT
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* 20020530 Joel Becker Add Matt Domsch's nowayout module
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* option
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* 20030116 Adam Belay Updated to the latest pnp code
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*
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/miscdevice.h>
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#include <linux/watchdog.h>
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#include <linux/ioport.h>
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#include <linux/spinlock.h>
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#include <linux/notifier.h>
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#include <linux/reboot.h>
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#include <linux/init.h>
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#include <linux/pnp.h>
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#include <linux/fs.h>
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#include <linux/semaphore.h>
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#include <linux/io.h>
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#include <linux/uaccess.h>
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#define SC1200_MODULE_VER "build 20020303"
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#define SC1200_MODULE_NAME "sc1200wdt"
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#define MAX_TIMEOUT 255 /* 255 minutes */
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#define PMIR (io) /* Power Management Index Register */
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#define PMDR (io+1) /* Power Management Data Register */
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/* Data Register indexes */
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#define FER1 0x00 /* Function enable register 1 */
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#define FER2 0x01 /* Function enable register 2 */
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#define PMC1 0x02 /* Power Management Ctrl 1 */
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#define PMC2 0x03 /* Power Management Ctrl 2 */
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#define PMC3 0x04 /* Power Management Ctrl 3 */
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#define WDTO 0x05 /* Watchdog timeout register */
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#define WDCF 0x06 /* Watchdog config register */
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#define WDST 0x07 /* Watchdog status register */
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/* WDCF bitfields - which devices assert WDO */
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#define KBC_IRQ 0x01 /* Keyboard Controller */
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#define MSE_IRQ 0x02 /* Mouse */
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#define UART1_IRQ 0x03 /* Serial0 */
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#define UART2_IRQ 0x04 /* Serial1 */
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/* 5 -7 are reserved */
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static int timeout = 1;
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static int io = -1;
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static int io_len = 2; /* for non plug and play */
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static unsigned long open_flag;
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static char expect_close;
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static DEFINE_SPINLOCK(sc1200wdt_lock); /* io port access serialisation */
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#if defined CONFIG_PNP
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static int isapnp = 1;
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static struct pnp_dev *wdt_dev;
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module_param(isapnp, int, 0);
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MODULE_PARM_DESC(isapnp,
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"When set to 0 driver ISA PnP support will be disabled");
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#endif
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module_param_hw(io, int, ioport, 0);
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MODULE_PARM_DESC(io, "io port");
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module_param(timeout, int, 0);
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MODULE_PARM_DESC(timeout, "range is 0-255 minutes, default is 1");
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static bool nowayout = WATCHDOG_NOWAYOUT;
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module_param(nowayout, bool, 0);
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MODULE_PARM_DESC(nowayout,
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"Watchdog cannot be stopped once started (default="
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__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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/* Read from Data Register */
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static inline void __sc1200wdt_read_data(unsigned char index,
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unsigned char *data)
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{
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outb_p(index, PMIR);
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*data = inb(PMDR);
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}
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static void sc1200wdt_read_data(unsigned char index, unsigned char *data)
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{
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spin_lock(&sc1200wdt_lock);
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__sc1200wdt_read_data(index, data);
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spin_unlock(&sc1200wdt_lock);
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}
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/* Write to Data Register */
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static inline void __sc1200wdt_write_data(unsigned char index,
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unsigned char data)
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{
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outb_p(index, PMIR);
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outb(data, PMDR);
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}
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static inline void sc1200wdt_write_data(unsigned char index,
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unsigned char data)
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{
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spin_lock(&sc1200wdt_lock);
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__sc1200wdt_write_data(index, data);
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spin_unlock(&sc1200wdt_lock);
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}
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static void sc1200wdt_start(void)
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{
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unsigned char reg;
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spin_lock(&sc1200wdt_lock);
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__sc1200wdt_read_data(WDCF, ®);
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/* assert WDO when any of the following interrupts are triggered too */
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reg |= (KBC_IRQ | MSE_IRQ | UART1_IRQ | UART2_IRQ);
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__sc1200wdt_write_data(WDCF, reg);
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/* set the timeout and get the ball rolling */
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__sc1200wdt_write_data(WDTO, timeout);
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spin_unlock(&sc1200wdt_lock);
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}
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static void sc1200wdt_stop(void)
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{
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sc1200wdt_write_data(WDTO, 0);
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}
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/* This returns the status of the WDO signal, inactive high. */
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static inline int sc1200wdt_status(void)
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{
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unsigned char ret;
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sc1200wdt_read_data(WDST, &ret);
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/* If the bit is inactive, the watchdog is enabled, so return
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* KEEPALIVEPING which is a bit of a kludge because there's nothing
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* else for enabled/disabled status
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*/
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return (ret & 0x01) ? 0 : WDIOF_KEEPALIVEPING;
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}
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static int sc1200wdt_open(struct inode *inode, struct file *file)
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{
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/* allow one at a time */
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if (test_and_set_bit(0, &open_flag))
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return -EBUSY;
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if (timeout > MAX_TIMEOUT)
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timeout = MAX_TIMEOUT;
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sc1200wdt_start();
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pr_info("Watchdog enabled, timeout = %d min(s)", timeout);
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return nonseekable_open(inode, file);
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}
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static long sc1200wdt_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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int new_timeout;
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void __user *argp = (void __user *)arg;
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int __user *p = argp;
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static const struct watchdog_info ident = {
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.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
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WDIOF_MAGICCLOSE,
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.firmware_version = 0,
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.identity = "PC87307/PC97307",
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};
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switch (cmd) {
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case WDIOC_GETSUPPORT:
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if (copy_to_user(argp, &ident, sizeof(ident)))
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return -EFAULT;
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return 0;
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case WDIOC_GETSTATUS:
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return put_user(sc1200wdt_status(), p);
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case WDIOC_GETBOOTSTATUS:
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return put_user(0, p);
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case WDIOC_SETOPTIONS:
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{
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int options, retval = -EINVAL;
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if (get_user(options, p))
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return -EFAULT;
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if (options & WDIOS_DISABLECARD) {
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sc1200wdt_stop();
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retval = 0;
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}
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if (options & WDIOS_ENABLECARD) {
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sc1200wdt_start();
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retval = 0;
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}
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return retval;
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}
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case WDIOC_KEEPALIVE:
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sc1200wdt_write_data(WDTO, timeout);
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return 0;
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case WDIOC_SETTIMEOUT:
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if (get_user(new_timeout, p))
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return -EFAULT;
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/* the API states this is given in secs */
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new_timeout /= 60;
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if (new_timeout < 0 || new_timeout > MAX_TIMEOUT)
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return -EINVAL;
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timeout = new_timeout;
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sc1200wdt_write_data(WDTO, timeout);
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/* fall through and return the new timeout */
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case WDIOC_GETTIMEOUT:
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return put_user(timeout * 60, p);
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default:
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return -ENOTTY;
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}
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}
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static int sc1200wdt_release(struct inode *inode, struct file *file)
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{
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if (expect_close == 42) {
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sc1200wdt_stop();
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pr_info("Watchdog disabled\n");
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} else {
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sc1200wdt_write_data(WDTO, timeout);
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pr_crit("Unexpected close!, timeout = %d min(s)\n", timeout);
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}
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clear_bit(0, &open_flag);
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expect_close = 0;
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return 0;
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}
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static ssize_t sc1200wdt_write(struct file *file, const char __user *data,
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size_t len, loff_t *ppos)
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{
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if (len) {
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if (!nowayout) {
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size_t i;
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expect_close = 0;
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for (i = 0; i != len; i++) {
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char c;
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if (get_user(c, data + i))
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return -EFAULT;
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if (c == 'V')
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expect_close = 42;
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}
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}
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sc1200wdt_write_data(WDTO, timeout);
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return len;
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}
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return 0;
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}
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static int sc1200wdt_notify_sys(struct notifier_block *this,
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unsigned long code, void *unused)
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{
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if (code == SYS_DOWN || code == SYS_HALT)
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sc1200wdt_stop();
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return NOTIFY_DONE;
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}
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static struct notifier_block sc1200wdt_notifier = {
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.notifier_call = sc1200wdt_notify_sys,
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};
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static const struct file_operations sc1200wdt_fops = {
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.owner = THIS_MODULE,
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.llseek = no_llseek,
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.write = sc1200wdt_write,
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.unlocked_ioctl = sc1200wdt_ioctl,
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.open = sc1200wdt_open,
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.release = sc1200wdt_release,
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};
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static struct miscdevice sc1200wdt_miscdev = {
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.minor = WATCHDOG_MINOR,
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.name = "watchdog",
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.fops = &sc1200wdt_fops,
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};
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static int __init sc1200wdt_probe(void)
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{
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/* The probe works by reading the PMC3 register's default value of 0x0e
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* there is one caveat, if the device disables the parallel port or any
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* of the UARTs we won't be able to detect it.
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* NB. This could be done with accuracy by reading the SID registers,
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* but we don't have access to those io regions.
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*/
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unsigned char reg;
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sc1200wdt_read_data(PMC3, ®);
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reg &= 0x0f; /* we don't want the UART busy bits */
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return (reg == 0x0e) ? 0 : -ENODEV;
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}
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#if defined CONFIG_PNP
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static struct pnp_device_id scl200wdt_pnp_devices[] = {
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/* National Semiconductor PC87307/PC97307 watchdog component */
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{.id = "NSC0800", .driver_data = 0},
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{.id = ""},
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};
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static int scl200wdt_pnp_probe(struct pnp_dev *dev,
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const struct pnp_device_id *dev_id)
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{
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/* this driver only supports one card at a time */
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if (wdt_dev || !isapnp)
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return -EBUSY;
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wdt_dev = dev;
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io = pnp_port_start(wdt_dev, 0);
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io_len = pnp_port_len(wdt_dev, 0);
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if (!request_region(io, io_len, SC1200_MODULE_NAME)) {
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pr_err("Unable to register IO port %#x\n", io);
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return -EBUSY;
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}
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pr_info("PnP device found at io port %#x/%d\n", io, io_len);
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return 0;
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}
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static void scl200wdt_pnp_remove(struct pnp_dev *dev)
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{
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if (wdt_dev) {
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release_region(io, io_len);
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wdt_dev = NULL;
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}
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}
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static struct pnp_driver scl200wdt_pnp_driver = {
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.name = "scl200wdt",
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.id_table = scl200wdt_pnp_devices,
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.probe = scl200wdt_pnp_probe,
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.remove = scl200wdt_pnp_remove,
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};
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#endif /* CONFIG_PNP */
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static int __init sc1200wdt_init(void)
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{
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int ret;
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pr_info("%s\n", SC1200_MODULE_VER);
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#if defined CONFIG_PNP
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if (isapnp) {
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ret = pnp_register_driver(&scl200wdt_pnp_driver);
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if (ret)
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goto out_clean;
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}
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#endif
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if (io == -1) {
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pr_err("io parameter must be specified\n");
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ret = -EINVAL;
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goto out_pnp;
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}
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#if defined CONFIG_PNP
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/* now that the user has specified an IO port and we haven't detected
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* any devices, disable pnp support */
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if (isapnp)
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pnp_unregister_driver(&scl200wdt_pnp_driver);
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isapnp = 0;
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#endif
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if (!request_region(io, io_len, SC1200_MODULE_NAME)) {
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pr_err("Unable to register IO port %#x\n", io);
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ret = -EBUSY;
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goto out_pnp;
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}
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ret = sc1200wdt_probe();
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if (ret)
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goto out_io;
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ret = register_reboot_notifier(&sc1200wdt_notifier);
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if (ret) {
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pr_err("Unable to register reboot notifier err = %d\n", ret);
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goto out_io;
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}
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ret = misc_register(&sc1200wdt_miscdev);
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if (ret) {
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pr_err("Unable to register miscdev on minor %d\n",
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WATCHDOG_MINOR);
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goto out_rbt;
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}
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/* ret = 0 */
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out_clean:
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return ret;
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out_rbt:
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unregister_reboot_notifier(&sc1200wdt_notifier);
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out_io:
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release_region(io, io_len);
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out_pnp:
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#if defined CONFIG_PNP
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if (isapnp)
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pnp_unregister_driver(&scl200wdt_pnp_driver);
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#endif
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goto out_clean;
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}
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static void __exit sc1200wdt_exit(void)
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{
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misc_deregister(&sc1200wdt_miscdev);
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unregister_reboot_notifier(&sc1200wdt_notifier);
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#if defined CONFIG_PNP
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if (isapnp)
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pnp_unregister_driver(&scl200wdt_pnp_driver);
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else
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#endif
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release_region(io, io_len);
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}
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module_init(sc1200wdt_init);
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module_exit(sc1200wdt_exit);
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MODULE_AUTHOR("Zwane Mwaikambo <zwane@commfireservices.com>");
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MODULE_DESCRIPTION(
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"Driver for National Semiconductor PC87307/PC97307 watchdog component");
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MODULE_LICENSE("GPL");
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