mconsole_kern.c

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static int mem_id(char **str, int *start_out, int *end_out)
{
	*start_out = 0;
	*end_out = 0;

	return 0;
}

static int mem_remove(int n, char **error_out)
{
	*error_out = "Memory doesn't support the remove operation";
	return -EBUSY;
}

static struct mc_device mem_mc = {
	.list		= LIST_HEAD_INIT(mem_mc.list),
	.name		= "mem",
	.config		= mem_config,
	.get_config	= mem_get_config,
	.id		= mem_id,
	.remove		= mem_remove,
};

static int __init mem_mc_init(void)
{
	if (can_drop_memory())
		mconsole_register_dev(&mem_mc);
	else printk(KERN_ERR "Can't release memory to the host - memory "
		    "hotplug won't be supported\n");
	return 0;
}

__initcall(mem_mc_init);

#define CONFIG_BUF_SIZE 64

static void mconsole_get_config(int (*get_config)(char *, char *, int,
						  char **),
				struct mc_request *req, char *name)
{
	char default_buf[CONFIG_BUF_SIZE], *error, *buf;
	int n, size;

	if (get_config == NULL) {
		mconsole_reply(req, "No get_config routine defined", 1, 0);
		return;
	}

	error = NULL;
	size = ARRAY_SIZE(default_buf);
	buf = default_buf;

	while (1) {
		n = (*get_config)(name, buf, size, &error);
		if (error != NULL) {
			mconsole_reply(req, error, 1, 0);
			goto out;
		}

		if (n <= size) {
			mconsole_reply(req, buf, 0, 0);
			goto out;
		}

		if (buf != default_buf)
			kfree(buf);

		size = n;
		buf = kmalloc(size, GFP_KERNEL);
		if (buf == NULL) {
			mconsole_reply(req, "Failed to allocate buffer", 1, 0);
			return;
		}
	}
 out:
	if (buf != default_buf)
		kfree(buf);
}

void mconsole_config(struct mc_request *req)
{
	struct mc_device *dev;
	char *ptr = req->request.data, *name, *error_string = "";
	int err;

	ptr += strlen("config");
	while (isspace(*ptr))
		ptr++;
	dev = mconsole_find_dev(ptr);
	if (dev == NULL) {
		mconsole_reply(req, "Bad configuration option", 1, 0);
		return;
	}

	name = &ptr[strlen(dev->name)];
	ptr = name;
	while ((*ptr != '=') && (*ptr != '\0'))
		ptr++;

	if (*ptr == '=') {
		err = (*dev->config)(name, &error_string);
		mconsole_reply(req, error_string, err, 0);
	}
	else mconsole_get_config(dev->get_config, req, name);
}

void mconsole_remove(struct mc_request *req)
{
	struct mc_device *dev;
	char *ptr = req->request.data, *err_msg = "";
	char error[256];
	int err, start, end, n;

	ptr += strlen("remove");
	while (isspace(*ptr)) ptr++;
	dev = mconsole_find_dev(ptr);
	if (dev == NULL) {
		mconsole_reply(req, "Bad remove option", 1, 0);
		return;
	}

	ptr = &ptr[strlen(dev->name)];

	err = 1;
	n = (*dev->id)(&ptr, &start, &end);
	if (n < 0) {
		err_msg = "Couldn't parse device number";
		goto out;
	}
	else if ((n < start) || (n > end)) {
		sprintf(error, "Invalid device number - must be between "
			"%d and %d", start, end);
		err_msg = error;
		goto out;
	}

	err_msg = NULL;
	err = (*dev->remove)(n, &err_msg);
	switch(err) {
	case 0:
		err_msg = "";
		break;
	case -ENODEV:
		if (err_msg == NULL)
			err_msg = "Device doesn't exist";
		break;
	case -EBUSY:
		if (err_msg == NULL)
			err_msg = "Device is currently open";
		break;
	default:
		break;
	}
out:
	mconsole_reply(req, err_msg, err, 0);
}

struct mconsole_output {
	struct list_head list;
	struct mc_request *req;
};

static DEFINE_SPINLOCK(client_lock);
static LIST_HEAD(clients);
static char console_buf[MCONSOLE_MAX_DATA];

static void console_write(struct console *console, const char *string,
			  unsigned int len)
{
	struct list_head *ele;
	int n;

	if (list_empty(&clients))
		return;

	while (len > 0) {
		n = min((size_t) len, ARRAY_SIZE(console_buf));
		strncpy(console_buf, string, n);
		string += n;
		len -= n;

		list_for_each(ele, &clients) {
			struct mconsole_output *entry;

			entry = list_entry(ele, struct mconsole_output, list);
			mconsole_reply_len(entry->req, console_buf, n, 0, 1);
		}
	}
}

static struct console mc_console = { .name	= "mc",
				     .write	= console_write,
				     .flags	= CON_ENABLED,
				     .index	= -1 };

static int mc_add_console(void)
{
	register_console(&mc_console);
	return 0;
}

late_initcall(mc_add_console);

static void with_console(struct mc_request *req, void (*proc)(void *),
			 void *arg)
{
	struct mconsole_output entry;
	unsigned long flags;

	entry.req = req;
	spin_lock_irqsave(&client_lock, flags);
	list_add(&entry.list, &clients);
	spin_unlock_irqrestore(&client_lock, flags);

	(*proc)(arg);

	mconsole_reply_len(req, "", 0, 0, 0);

	spin_lock_irqsave(&client_lock, flags);
	list_del(&entry.list);
	spin_unlock_irqrestore(&client_lock, flags);
}

#ifdef CONFIG_MAGIC_SYSRQ

#include <linux/sysrq.h>

static void sysrq_proc(void *arg)
{
	char *op = arg;
	handle_sysrq(*op, NULL);
}

void mconsole_sysrq(struct mc_request *req)
{
	char *ptr = req->request.data;

	ptr += strlen("sysrq");
	while (isspace(*ptr)) ptr++;

	/*
	 * With 'b', the system will shut down without a chance to reply,
	 * so in this case, we reply first.
	 */
	if (*ptr == 'b')
		mconsole_reply(req, "", 0, 0);

	with_console(req, sysrq_proc, ptr);
}
#else
void mconsole_sysrq(struct mc_request *req)
{
	mconsole_reply(req, "Sysrq not compiled in", 1, 0);
}
#endif

static void stack_proc(void *arg)
{
	struct task_struct *from = current, *to = arg;

	to->thread.saved_task = from;
	switch_to(from, to, from);
}

/*
 * Mconsole stack trace
 *  Added by Allan Graves, Jeff Dike
 *  Dumps a stacks registers to the linux console.
 *  Usage stack <pid>.
 */
void mconsole_stack(struct mc_request *req)
{
	char *ptr = req->request.data;
	int pid_requested= -1;
	struct task_struct *from = NULL;
	struct task_struct *to = NULL;

	/*
	 * Would be nice:
	 * 1) Send showregs output to mconsole.
	 * 2) Add a way to stack dump all pids.
	 */

	ptr += strlen("stack");
	while (isspace(*ptr))
		ptr++;

	/*
	 * Should really check for multiple pids or reject bad args here
	 */
	/* What do the arguments in mconsole_reply mean? */
	if (sscanf(ptr, "%d", &pid_requested) == 0) {
		mconsole_reply(req, "Please specify a pid", 1, 0);
		return;
	}

	from = current;

	to = find_task_by_pid(pid_requested);
	if ((to == NULL) || (pid_requested == 0)) {
		mconsole_reply(req, "Couldn't find that pid", 1, 0);
		return;
	}
	with_console(req, stack_proc, to);
}

/*
 * Changed by mconsole_setup, which is __setup, and called before SMP is
 * active.
 */
static char *notify_socket = NULL;

static int __init mconsole_init(void)
{
	/* long to avoid size mismatch warnings from gcc */
	long sock;
	int err;
	char file[256];

	if (umid_file_name("mconsole", file, sizeof(file)))
		return -1;
	snprintf(mconsole_socket_name, sizeof(file), "%s", file);

	sock = os_create_unix_socket(file, sizeof(file), 1);
	if (sock < 0) {
		printk(KERN_ERR "Failed to initialize management console\n");
		return 1;
	}

	register_reboot_notifier(&reboot_notifier);

	err = um_request_irq(MCONSOLE_IRQ, sock, IRQ_READ, mconsole_interrupt,
			     IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM,
			     "mconsole", (void *)sock);
	if (err) {
		printk(KERN_ERR "Failed to get IRQ for management console\n");
		return 1;
	}

	if (notify_socket != NULL) {
		notify_socket = kstrdup(notify_socket, GFP_KERNEL);
		if (notify_socket != NULL)
			mconsole_notify(notify_socket, MCONSOLE_SOCKET,
					mconsole_socket_name,
					strlen(mconsole_socket_name) + 1);
		else printk(KERN_ERR "mconsole_setup failed to strdup "
			    "string\n");
	}

	printk(KERN_INFO "mconsole (version %d) initialized on %s\n",
	       MCONSOLE_VERSION, mconsole_socket_name);
	return 0;
}

__initcall(mconsole_init);

static int write_proc_mconsole(struct file *file, const char __user *buffer,
			       unsigned long count, void *data)
{
	char *buf;

	buf = kmalloc(count + 1, GFP_KERNEL);
	if (buf == NULL)
		return -ENOMEM;

	if (copy_from_user(buf, buffer, count)) {
		count = -EFAULT;
		goto out;
	}

	buf[count] = '\0';

	mconsole_notify(notify_socket, MCONSOLE_USER_NOTIFY, buf, count);
 out:
	kfree(buf);
	return count;
}

static int create_proc_mconsole(void)
{
	struct proc_dir_entry *ent;

	if (notify_socket == NULL)
		return 0;

	ent = create_proc_entry("mconsole", S_IFREG | 0200, NULL);
	if (ent == NULL) {
		printk(KERN_INFO "create_proc_mconsole : create_proc_entry "
		       "failed\n");
		return 0;
	}

	ent->read_proc = NULL;
	ent->write_proc = write_proc_mconsole;
	return 0;
}

static DEFINE_SPINLOCK(notify_spinlock);

void lock_notify(void)
{
	spin_lock(&notify_spinlock);
}

void unlock_notify(void)
{
	spin_unlock(&notify_spinlock);
}

__initcall(create_proc_mconsole);

#define NOTIFY "notify:"

static int mconsole_setup(char *str)
{
	if (!strncmp(str, NOTIFY, strlen(NOTIFY))) {
		str += strlen(NOTIFY);
		notify_socket = str;
	}
	else printk(KERN_ERR "mconsole_setup : Unknown option - '%s'\n", str);
	return 1;
}

__setup("mconsole=", mconsole_setup);

__uml_help(mconsole_setup,
"mconsole=notify:<socket>\n"
"    Requests that the mconsole driver send a message to the named Unix\n"
"    socket containing the name of the mconsole socket.  This also serves\n"
"    to notify outside processes when UML has booted far enough to respond\n"
"    to mconsole requests.\n\n"
);

static int notify_panic(struct notifier_block *self, unsigned long unused1,
			void *ptr)
{
	char *message = ptr;

	if (notify_socket == NULL)
		return 0;

	mconsole_notify(notify_socket, MCONSOLE_PANIC, message,
			strlen(message) + 1);
	return 0;
}

static struct notifier_block panic_exit_notifier = {
	.notifier_call 		= notify_panic,
	.next 			= NULL,
	.priority 		= 1
};

static int add_notifier(void)
{
	atomic_notifier_chain_register(&panic_notifier_list,
			&panic_exit_notifier);
	return 0;
}

__initcall(add_notifier);

char *mconsole_notify_socket(void)
{
	return notify_socket;
}

EXPORT_SYMBOL(mconsole_notify_socket);