drivers/s390/char/vmwatchdog.c - kernel/msm - Gitiles

 /*
  * Watchdog implementation based on z/VM Watchdog Timer API
  *
  * The user space watchdog daemon can use this driver as
  * /dev/vmwatchdog to have z/VM execute the specified CP
  * command when the timeout expires. The default command is
  * "IPL", which which cause an immediate reboot.
  */
 #include <linux/init.h>
 #include <linux/fs.h>
 #include <linux/kernel.h>
 #include <linux/miscdevice.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/watchdog.h>

 #include <asm/ebcdic.h>
 #include <asm/io.h>
 #include <asm/uaccess.h>

 #define MAX_CMDLEN 240
 #define MIN_INTERVAL 15
 static char vmwdt_cmd[MAX_CMDLEN] = "IPL";
 static int vmwdt_conceal;

 static int vmwdt_nowayout = WATCHDOG_NOWAYOUT;

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");
 MODULE_DESCRIPTION("z/VM Watchdog Timer");
 module_param_string(cmd, vmwdt_cmd, MAX_CMDLEN, 0644);
 MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers");
 module_param_named(conceal, vmwdt_conceal, bool, 0644);
 MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog "
 		" is active");
 module_param_named(nowayout, vmwdt_nowayout, bool, 0);
 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started"
 		" (default=CONFIG_WATCHDOG_NOWAYOUT)");
 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

 static unsigned int vmwdt_interval = 60;
 static unsigned long vmwdt_is_open;
 static int vmwdt_expect_close;

 enum vmwdt_func {
 	/* function codes */
 	wdt_init   = 0,
 	wdt_change = 1,
 	wdt_cancel = 2,
 	/* flags */
 	wdt_conceal = 0x80000000,
 };

 static int __diag288(enum vmwdt_func func, unsigned int timeout,
 			    char *cmd, size_t len)
 {
 	register unsigned long __func asm("2");
 	register unsigned long __timeout asm("3");
 	register unsigned long __cmdp asm("4");
 	register unsigned long __cmdl asm("5");
 	int err;

 	__func = func;
 	__timeout = timeout;
 	__cmdp = virt_to_phys(cmd);
 	__cmdl = len;
 	err = 0;
 	asm volatile (
 #ifdef CONFIG_64BIT
 		       "diag %2,%4,0x288\n"
 		"1:	\n"
 		".section .fixup,\"ax\"\n"
 		"2:	lghi %0,%1\n"
 		"	jg 1b\n"
 		".previous\n"
 		".section __ex_table,\"a\"\n"
 		"	.align 8\n"
 		"	.quad 1b,2b\n"
 		".previous\n"
 #else
 		       "diag %2,%4,0x288\n"
 		"1:	\n"
 		".section .fixup,\"ax\"\n"
 		"2:	lhi %0,%1\n"
 		"	bras 1,3f\n"
 		"	.long 1b\n"
 		"3:	l 1,0(1)\n"
 		"	br 1\n"
 		".previous\n"
 		".section __ex_table,\"a\"\n"
 		"	.align 4\n"
 		"	.long 1b,2b\n"
 		".previous\n"
 #endif
 		: "+&d"(err)
 		: "i"(-EINVAL), "d"(__func), "d"(__timeout),
 		  "d"(__cmdp), "d"(__cmdl)
 		: "1", "cc");
 	return err;
 }

 static int vmwdt_keepalive(void)
 {
 	/* we allocate new memory every time to avoid having
 	 * to track the state. static allocation is not an
 	 * option since that might not be contiguous in real
 	 * storage in case of a modular build */
 	static char *ebc_cmd;
 	size_t len;
 	int ret;
 	unsigned int func;

 	ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
 	if (!ebc_cmd)
 		return -ENOMEM;

 	len = strlcpy(ebc_cmd, vmwdt_cmd, MAX_CMDLEN);
 	ASCEBC(ebc_cmd, MAX_CMDLEN);
 	EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);

 	func = vmwdt_conceal ? (wdt_init | wdt_conceal) : wdt_init;
 	ret = __diag288(func, vmwdt_interval, ebc_cmd, len);
 	kfree(ebc_cmd);

 	if (ret) {
 		printk(KERN_WARNING "%s: problem setting interval %d, "
 			"cmd %s\n", __FUNCTION__, vmwdt_interval,
 			vmwdt_cmd);
 	}
 	return ret;
 }

 static int vmwdt_disable(void)
 {
 	int ret = __diag288(wdt_cancel, 0, "", 0);
 	if (ret) {
 		printk(KERN_WARNING "%s: problem disabling watchdog\n",
 			__FUNCTION__);
 	}
 	return ret;
 }

 static int __init vmwdt_probe(void)
 {
 	/* there is no real way to see if the watchdog is supported,
 	 * so we try initializing it with a NOP command ("BEGIN")
 	 * that won't cause any harm even if the following disable
 	 * fails for some reason */
 	static char __initdata ebc_begin[] = {
 		194, 197, 199, 201, 213
 	};
 	if (__diag288(wdt_init, 15, ebc_begin, sizeof(ebc_begin)) != 0) {
 		printk(KERN_INFO "z/VM watchdog not available\n");
 		return -EINVAL;
 	}
 	return vmwdt_disable();
 }

 static int vmwdt_open(struct inode *i, struct file *f)
 {
 	int ret;
 	if (test_and_set_bit(0, &vmwdt_is_open))
 		return -EBUSY;
 	ret = vmwdt_keepalive();
 	if (ret)
 		clear_bit(0, &vmwdt_is_open);
 	return ret ? ret : nonseekable_open(i, f);
 }

 static int vmwdt_close(struct inode *i, struct file *f)
 {
 	if (vmwdt_expect_close == 42)
 		vmwdt_disable();
 	vmwdt_expect_close = 0;
 	clear_bit(0, &vmwdt_is_open);
 	return 0;
 }

 static struct watchdog_info vmwdt_info = {
 	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 	.firmware_version = 0,
 	.identity = "z/VM Watchdog Timer",
 };

 static int vmwdt_ioctl(struct inode *i, struct file *f,
 			  unsigned int cmd, unsigned long arg)
 {
 	switch (cmd) {
 	case WDIOC_GETSUPPORT:
 		if (copy_to_user((void __user *)arg, &vmwdt_info,
 					sizeof(vmwdt_info)))
 			return -EFAULT;
 		return 0;
 	case WDIOC_GETSTATUS:
 	case WDIOC_GETBOOTSTATUS:
 		return put_user(0, (int *)arg);
 	case WDIOC_GETTEMP:
 		return -EINVAL;
 	case WDIOC_SETOPTIONS:
 		{
 			int options, ret;
 			if (get_user(options, (int __user *)arg))
 				return -EFAULT;
 			ret = -EINVAL;
 			if (options & WDIOS_DISABLECARD) {
 				ret = vmwdt_disable();
 				if (ret)
 					return ret;
 			}
 			if (options & WDIOS_ENABLECARD) {
 				ret = vmwdt_keepalive();
 			}
 			return ret;
 		}
 	case WDIOC_GETTIMEOUT:
 		return put_user(vmwdt_interval, (int __user *)arg);
 	case WDIOC_SETTIMEOUT:
 		{
 			int interval;
 			if (get_user(interval, (int __user *)arg))
 				return -EFAULT;
 			if (interval < MIN_INTERVAL)
 				return -EINVAL;
 			vmwdt_interval = interval;
 		}
 		return vmwdt_keepalive();
 	case WDIOC_KEEPALIVE:
 		return vmwdt_keepalive();
 	}

 	return -EINVAL;
 }

 static ssize_t vmwdt_write(struct file *f, const char __user *buf,
 				size_t count, loff_t *ppos)
 {
 	if(count) {
 		if (!vmwdt_nowayout) {
 			size_t i;

 			/* note: just in case someone wrote the magic character
 			 * five months ago... */
 			vmwdt_expect_close = 0;

 			for (i = 0; i != count; i++) {
 				char c;
 				if (get_user(c, buf+i))
 					return -EFAULT;
 				if (c == 'V')
 					vmwdt_expect_close = 42;
 			}
 		}
 		/* someone wrote to us, we should restart timer */
 		vmwdt_keepalive();
 	}
 	return count;
 }

 static struct file_operations vmwdt_fops = {
 	.open    = &vmwdt_open,
 	.release = &vmwdt_close,
 	.ioctl   = &vmwdt_ioctl,
 	.write   = &vmwdt_write,
 	.owner   = THIS_MODULE,
 };

 static struct miscdevice vmwdt_dev = {
 	.minor      = WATCHDOG_MINOR,
 	.name       = "watchdog",
 	.fops       = &vmwdt_fops,
 };

 static int __init vmwdt_init(void)
 {
 	int ret;

 	ret = vmwdt_probe();
 	if (ret)
 		return ret;
 	return misc_register(&vmwdt_dev);
 }
 module_init(vmwdt_init);

 static void __exit vmwdt_exit(void)
 {
 	WARN_ON(misc_deregister(&vmwdt_dev) != 0);
 }
 module_exit(vmwdt_exit);
	/*
	* Watchdog implementation based on z/VM Watchdog Timer API
	*
	* The user space watchdog daemon can use this driver as
	* /dev/vmwatchdog to have z/VM execute the specified CP
	* command when the timeout expires. The default command is
	* "IPL", which which cause an immediate reboot.
	*/
	#include <linux/init.h>
	#include <linux/fs.h>
	#include <linux/kernel.h>
	#include <linux/miscdevice.h>
	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/watchdog.h>

	#include <asm/ebcdic.h>
	#include <asm/io.h>
	#include <asm/uaccess.h>

	#define MAX_CMDLEN 240
	#define MIN_INTERVAL 15
	static char vmwdt_cmd[MAX_CMDLEN] = "IPL";
	static int vmwdt_conceal;

	static int vmwdt_nowayout = WATCHDOG_NOWAYOUT;

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");
	MODULE_DESCRIPTION("z/VM Watchdog Timer");
	module_param_string(cmd, vmwdt_cmd, MAX_CMDLEN, 0644);
	MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers");
	module_param_named(conceal, vmwdt_conceal, bool, 0644);
	MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog "
	" is active");
	module_param_named(nowayout, vmwdt_nowayout, bool, 0);
	MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started"
	" (default=CONFIG_WATCHDOG_NOWAYOUT)");
	MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

	static unsigned int vmwdt_interval = 60;
	static unsigned long vmwdt_is_open;
	static int vmwdt_expect_close;

	enum vmwdt_func {
	/* function codes */
	wdt_init = 0,
	wdt_change = 1,
	wdt_cancel = 2,
	/* flags */
	wdt_conceal = 0x80000000,
	};

	static int __diag288(enum vmwdt_func func, unsigned int timeout,
	char *cmd, size_t len)
	{
	register unsigned long __func asm("2");
	register unsigned long __timeout asm("3");
	register unsigned long __cmdp asm("4");
	register unsigned long __cmdl asm("5");
	int err;

	__func = func;
	__timeout = timeout;
	__cmdp = virt_to_phys(cmd);
	__cmdl = len;
	err = 0;
	asm volatile (
	#ifdef CONFIG_64BIT
	"diag %2,%4,0x288\n"
	"1: \n"
	".section .fixup,\"ax\"\n"
	"2: lghi %0,%1\n"
	" jg 1b\n"
	".previous\n"
	".section __ex_table,\"a\"\n"
	" .align 8\n"
	" .quad 1b,2b\n"
	".previous\n"
	#else
	"diag %2,%4,0x288\n"
	"1: \n"
	".section .fixup,\"ax\"\n"
	"2: lhi %0,%1\n"
	" bras 1,3f\n"
	" .long 1b\n"
	"3: l 1,0(1)\n"
	" br 1\n"
	".previous\n"
	".section __ex_table,\"a\"\n"
	" .align 4\n"
	" .long 1b,2b\n"
	".previous\n"
	#endif
	: "+&d"(err)
	: "i"(-EINVAL), "d"(__func), "d"(__timeout),
	"d"(__cmdp), "d"(__cmdl)
	: "1", "cc");
	return err;
	}

	static int vmwdt_keepalive(void)
	{
	/* we allocate new memory every time to avoid having
	* to track the state. static allocation is not an
	* option since that might not be contiguous in real
	* storage in case of a modular build */
	static char *ebc_cmd;
	size_t len;
	int ret;
	unsigned int func;

	ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
	if (!ebc_cmd)
	return -ENOMEM;

	len = strlcpy(ebc_cmd, vmwdt_cmd, MAX_CMDLEN);
	ASCEBC(ebc_cmd, MAX_CMDLEN);
	EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);

	func = vmwdt_conceal ? (wdt_init \| wdt_conceal) : wdt_init;
	ret = __diag288(func, vmwdt_interval, ebc_cmd, len);
	kfree(ebc_cmd);

	if (ret) {
	printk(KERN_WARNING "%s: problem setting interval %d, "
	"cmd %s\n", __FUNCTION__, vmwdt_interval,
	vmwdt_cmd);
	}
	return ret;
	}

	static int vmwdt_disable(void)
	{
	int ret = __diag288(wdt_cancel, 0, "", 0);
	if (ret) {
	printk(KERN_WARNING "%s: problem disabling watchdog\n",
	__FUNCTION__);
	}
	return ret;
	}

	static int __init vmwdt_probe(void)
	{
	/* there is no real way to see if the watchdog is supported,
	* so we try initializing it with a NOP command ("BEGIN")
	* that won't cause any harm even if the following disable
	* fails for some reason */
	static char __initdata ebc_begin[] = {
	194, 197, 199, 201, 213
	};
	if (__diag288(wdt_init, 15, ebc_begin, sizeof(ebc_begin)) != 0) {
	printk(KERN_INFO "z/VM watchdog not available\n");
	return -EINVAL;
	}
	return vmwdt_disable();
	}

	static int vmwdt_open(struct inode i, struct file f)
	{
	int ret;
	if (test_and_set_bit(0, &vmwdt_is_open))
	return -EBUSY;
	ret = vmwdt_keepalive();
	if (ret)
	clear_bit(0, &vmwdt_is_open);
	return ret ? ret : nonseekable_open(i, f);
	}

	static int vmwdt_close(struct inode i, struct file f)
	{
	if (vmwdt_expect_close == 42)
	vmwdt_disable();
	vmwdt_expect_close = 0;
	clear_bit(0, &vmwdt_is_open);
	return 0;
	}

	static struct watchdog_info vmwdt_info = {
	.options = WDIOF_SETTIMEOUT \| WDIOF_KEEPALIVEPING \| WDIOF_MAGICCLOSE,
	.firmware_version = 0,
	.identity = "z/VM Watchdog Timer",
	};

	static int vmwdt_ioctl(struct inode i, struct file f,
	unsigned int cmd, unsigned long arg)
	{
	switch (cmd) {
	case WDIOC_GETSUPPORT:
	if (copy_to_user((void __user *)arg, &vmwdt_info,
	sizeof(vmwdt_info)))
	return -EFAULT;
	return 0;
	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
	return put_user(0, (int *)arg);
	case WDIOC_GETTEMP:
	return -EINVAL;
	case WDIOC_SETOPTIONS:
	{
	int options, ret;
	if (get_user(options, (int __user *)arg))
	return -EFAULT;
	ret = -EINVAL;
	if (options & WDIOS_DISABLECARD) {
	ret = vmwdt_disable();
	if (ret)
	return ret;
	}
	if (options & WDIOS_ENABLECARD) {
	ret = vmwdt_keepalive();
	}
	return ret;
	}
	case WDIOC_GETTIMEOUT:
	return put_user(vmwdt_interval, (int __user *)arg);
	case WDIOC_SETTIMEOUT:
	{
	int interval;
	if (get_user(interval, (int __user *)arg))
	return -EFAULT;
	if (interval < MIN_INTERVAL)
	return -EINVAL;
	vmwdt_interval = interval;
	}
	return vmwdt_keepalive();
	case WDIOC_KEEPALIVE:
	return vmwdt_keepalive();
	}

	return -EINVAL;
	}

	static ssize_t vmwdt_write(struct file f, const char __user buf,
	size_t count, loff_t *ppos)
	{
	if(count) {
	if (!vmwdt_nowayout) {
	size_t i;

	/* note: just in case someone wrote the magic character
	* five months ago... */
	vmwdt_expect_close = 0;

	for (i = 0; i != count; i++) {
	char c;
	if (get_user(c, buf+i))
	return -EFAULT;
	if (c == 'V')
	vmwdt_expect_close = 42;
	}
	}
	/* someone wrote to us, we should restart timer */
	vmwdt_keepalive();
	}
	return count;
	}

	static struct file_operations vmwdt_fops = {
	.open = &vmwdt_open,
	.release = &vmwdt_close,
	.ioctl = &vmwdt_ioctl,
	.write = &vmwdt_write,
	.owner = THIS_MODULE,
	};

	static struct miscdevice vmwdt_dev = {
	.minor = WATCHDOG_MINOR,
	.name = "watchdog",
	.fops = &vmwdt_fops,
	};

	static int __init vmwdt_init(void)
	{
	int ret;

	ret = vmwdt_probe();
	if (ret)
	return ret;
	return misc_register(&vmwdt_dev);
	}
	module_init(vmwdt_init);

	static void __exit vmwdt_exit(void)
	{
	WARN_ON(misc_deregister(&vmwdt_dev) != 0);
	}
	module_exit(vmwdt_exit);