[net-next-2.6.git] / drivers / char / sysrq.c

/* -*- linux-c -*-
 *
 *	$Id: sysrq.c,v 1.15 1998/08/23 14:56:41 mj Exp $
 *
 *	Linux Magic System Request Key Hacks
 *
 *	(c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
 *	based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz>
 *
 *	(c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
 *	overhauled to use key registration
 *	based upon discusions in irc://irc.openprojects.net/#kernelnewbies
 */

#include <linux/config.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/tty.h>
#include <linux/mount.h>
#include <linux/kdev_t.h>
#include <linux/major.h>
#include <linux/reboot.h>
#include <linux/sysrq.h>
#include <linux/kbd_kern.h>
#include <linux/quotaops.h>
#include <linux/smp_lock.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/suspend.h>
#include <linux/writeback.h>
#include <linux/buffer_head.h>		/* for fsync_bdev() */
#include <linux/swap.h>
#include <linux/spinlock.h>
#include <linux/vt_kern.h>
#include <linux/workqueue.h>
#include <linux/kexec.h>

#include <asm/ptrace.h>

/* Whether we react on sysrq keys or just ignore them */
int sysrq_enabled = 1;

/* Loglevel sysrq handler */
static void sysrq_handle_loglevel(int key, struct pt_regs *pt_regs,
				  struct tty_struct *tty) 
{
	int i;
	i = key - '0';
	console_loglevel = 7;
	printk("Loglevel set to %d\n", i);
	console_loglevel = i;
}	
static struct sysrq_key_op sysrq_loglevel_op = {
	.handler	= sysrq_handle_loglevel,
	.help_msg	= "loglevel0-8",
	.action_msg	= "Changing Loglevel",
	.enable_mask	= SYSRQ_ENABLE_LOG,
};


/* SAK sysrq handler */
#ifdef CONFIG_VT
static void sysrq_handle_SAK(int key, struct pt_regs *pt_regs,
			     struct tty_struct *tty) 
{
	if (tty)
		do_SAK(tty);
	reset_vc(vc_cons[fg_console].d);
}
static struct sysrq_key_op sysrq_SAK_op = {
	.handler	= sysrq_handle_SAK,
	.help_msg	= "saK",
	.action_msg	= "SAK",
	.enable_mask	= SYSRQ_ENABLE_KEYBOARD,
};
#endif

#ifdef CONFIG_VT
/* unraw sysrq handler */
static void sysrq_handle_unraw(int key, struct pt_regs *pt_regs,
			       struct tty_struct *tty) 
{
	struct kbd_struct *kbd = &kbd_table[fg_console];

	if (kbd)
		kbd->kbdmode = VC_XLATE;
}
static struct sysrq_key_op sysrq_unraw_op = {
	.handler	= sysrq_handle_unraw,
	.help_msg	= "unRaw",
	.action_msg	= "Keyboard mode set to XLATE",
	.enable_mask	= SYSRQ_ENABLE_KEYBOARD,
};
#endif /* CONFIG_VT */

#ifdef CONFIG_KEXEC
/* crashdump sysrq handler */
static void sysrq_handle_crashdump(int key, struct pt_regs *pt_regs,
				struct tty_struct *tty)
{
	crash_kexec(pt_regs);
}
static struct sysrq_key_op sysrq_crashdump_op = {
	.handler	= sysrq_handle_crashdump,
	.help_msg	= "Crashdump",
	.action_msg	= "Trigger a crashdump",
	.enable_mask	= SYSRQ_ENABLE_DUMP,
};
#endif

/* reboot sysrq handler */
static void sysrq_handle_reboot(int key, struct pt_regs *pt_regs,
				struct tty_struct *tty) 
{
	local_irq_enable();
	emergency_restart();
}

static struct sysrq_key_op sysrq_reboot_op = {
	.handler	= sysrq_handle_reboot,
	.help_msg	= "reBoot",
	.action_msg	= "Resetting",
	.enable_mask	= SYSRQ_ENABLE_BOOT,
};

static void sysrq_handle_sync(int key, struct pt_regs *pt_regs,
			      struct tty_struct *tty) 
{
	emergency_sync();
}

static struct sysrq_key_op sysrq_sync_op = {
	.handler	= sysrq_handle_sync,
	.help_msg	= "Sync",
	.action_msg	= "Emergency Sync",
	.enable_mask	= SYSRQ_ENABLE_SYNC,
};

static void sysrq_handle_mountro(int key, struct pt_regs *pt_regs,
				 struct tty_struct *tty) 
{
	emergency_remount();
}

static struct sysrq_key_op sysrq_mountro_op = {
	.handler	= sysrq_handle_mountro,
	.help_msg	= "Unmount",
	.action_msg	= "Emergency Remount R/O",
	.enable_mask	= SYSRQ_ENABLE_REMOUNT,
};

/* END SYNC SYSRQ HANDLERS BLOCK */


/* SHOW SYSRQ HANDLERS BLOCK */

static void sysrq_handle_showregs(int key, struct pt_regs *pt_regs,
				  struct tty_struct *tty) 
{
	if (pt_regs)
		show_regs(pt_regs);
}
static struct sysrq_key_op sysrq_showregs_op = {
	.handler	= sysrq_handle_showregs,
	.help_msg	= "showPc",
	.action_msg	= "Show Regs",
	.enable_mask	= SYSRQ_ENABLE_DUMP,
};


static void sysrq_handle_showstate(int key, struct pt_regs *pt_regs,
				   struct tty_struct *tty) 
{
	show_state();
}
static struct sysrq_key_op sysrq_showstate_op = {
	.handler	= sysrq_handle_showstate,
	.help_msg	= "showTasks",
	.action_msg	= "Show State",
	.enable_mask	= SYSRQ_ENABLE_DUMP,
};


static void sysrq_handle_showmem(int key, struct pt_regs *pt_regs,
				 struct tty_struct *tty) 
{
	show_mem();
}
static struct sysrq_key_op sysrq_showmem_op = {
	.handler	= sysrq_handle_showmem,
	.help_msg	= "showMem",
	.action_msg	= "Show Memory",
	.enable_mask	= SYSRQ_ENABLE_DUMP,
};

/* SHOW SYSRQ HANDLERS BLOCK */


/* SIGNAL SYSRQ HANDLERS BLOCK */

/* signal sysrq helper function
 * Sends a signal to all user processes */
static void send_sig_all(int sig)
{
	struct task_struct *p;

	for_each_process(p) {
		if (p->mm && p->pid != 1)
			/* Not swapper, init nor kernel thread */
			force_sig(sig, p);
	}
}

static void sysrq_handle_term(int key, struct pt_regs *pt_regs,
			      struct tty_struct *tty) 
{
	send_sig_all(SIGTERM);
	console_loglevel = 8;
}
static struct sysrq_key_op sysrq_term_op = {
	.handler	= sysrq_handle_term,
	.help_msg	= "tErm",
	.action_msg	= "Terminate All Tasks",
	.enable_mask	= SYSRQ_ENABLE_SIGNAL,
};

static void moom_callback(void *ignored)
{
	out_of_memory(GFP_KERNEL, 0);
}

static DECLARE_WORK(moom_work, moom_callback, NULL);

static void sysrq_handle_moom(int key, struct pt_regs *pt_regs,
			      struct tty_struct *tty)
{
	schedule_work(&moom_work);
}
static struct sysrq_key_op sysrq_moom_op = {
	.handler	= sysrq_handle_moom,
	.help_msg	= "Full",
	.action_msg	= "Manual OOM execution",
};

static void sysrq_handle_kill(int key, struct pt_regs *pt_regs,
			      struct tty_struct *tty) 
{
	send_sig_all(SIGKILL);
	console_loglevel = 8;
}
static struct sysrq_key_op sysrq_kill_op = {
	.handler	= sysrq_handle_kill,
	.help_msg	= "kIll",
	.action_msg	= "Kill All Tasks",
	.enable_mask	= SYSRQ_ENABLE_SIGNAL,
};

/* END SIGNAL SYSRQ HANDLERS BLOCK */

static void sysrq_handle_unrt(int key, struct pt_regs *pt_regs,
				struct tty_struct *tty)
{
	normalize_rt_tasks();
}
static struct sysrq_key_op sysrq_unrt_op = {
	.handler	= sysrq_handle_unrt,
	.help_msg	= "Nice",
	.action_msg	= "Nice All RT Tasks",
	.enable_mask	= SYSRQ_ENABLE_RTNICE,
};

/* Key Operations table and lock */
static DEFINE_SPINLOCK(sysrq_key_table_lock);
#define SYSRQ_KEY_TABLE_LENGTH 36
static struct sysrq_key_op *sysrq_key_table[SYSRQ_KEY_TABLE_LENGTH] = {
/* 0 */	&sysrq_loglevel_op,
/* 1 */	&sysrq_loglevel_op,
/* 2 */	&sysrq_loglevel_op,
/* 3 */	&sysrq_loglevel_op,
/* 4 */	&sysrq_loglevel_op,
/* 5 */	&sysrq_loglevel_op,
/* 6 */	&sysrq_loglevel_op,
/* 7 */	&sysrq_loglevel_op,
/* 8 */	&sysrq_loglevel_op,
/* 9 */	&sysrq_loglevel_op,
/* a */	NULL, /* Don't use for system provided sysrqs,
		 it is handled specially on the sparc
		 and will never arrive */
/* b */	&sysrq_reboot_op,
#ifdef CONFIG_KEXEC
/* c */ &sysrq_crashdump_op,
#else
/* c */	NULL,
#endif
/* d */ NULL,
/* e */	&sysrq_term_op,
/* f */	&sysrq_moom_op,
/* g */	NULL,
/* h */	NULL,
/* i */	&sysrq_kill_op,
/* j */	NULL,
#ifdef CONFIG_VT
/* k */	&sysrq_SAK_op,
#else
/* k */	NULL,
#endif
/* l */	NULL,
/* m */	&sysrq_showmem_op,
/* n */	&sysrq_unrt_op,
/* o */	NULL, /* This will often be registered
		 as 'Off' at init time */
/* p */	&sysrq_showregs_op,
/* q */	NULL,
#ifdef CONFIG_VT
/* r */	&sysrq_unraw_op,
#else
/* r */ NULL,
#endif
/* s */	&sysrq_sync_op,
/* t */	&sysrq_showstate_op,
/* u */	&sysrq_mountro_op,
/* v */	NULL, /* May be assigned at init time by SMP VOYAGER */
/* w */	NULL,
/* x */	NULL,
/* y */	NULL,
/* z */	NULL
};

/* key2index calculation, -1 on invalid index */
static int sysrq_key_table_key2index(int key) {
	int retval;
	if ((key >= '0') && (key <= '9')) {
		retval = key - '0';
	} else if ((key >= 'a') && (key <= 'z')) {
		retval = key + 10 - 'a';
	} else {
		retval = -1;
	}
	return retval;
}

/*
 * get and put functions for the table, exposed to modules.
 */

struct sysrq_key_op *__sysrq_get_key_op (int key) {
        struct sysrq_key_op *op_p;
        int i;
	
	i = sysrq_key_table_key2index(key);
        op_p = (i == -1) ? NULL : sysrq_key_table[i];
        return op_p;
}

void __sysrq_put_key_op (int key, struct sysrq_key_op *op_p) {
        int i;

	i = sysrq_key_table_key2index(key);
        if (i != -1)
                sysrq_key_table[i] = op_p;
}

/*
 * This is the non-locking version of handle_sysrq
 * It must/can only be called by sysrq key handlers,
 * as they are inside of the lock
 */

void __handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty, int check_mask)
{
	struct sysrq_key_op *op_p;
	int orig_log_level;
	int i, j;
	unsigned long flags;

	spin_lock_irqsave(&sysrq_key_table_lock, flags);
	orig_log_level = console_loglevel;
	console_loglevel = 7;
	printk(KERN_INFO "SysRq : ");

        op_p = __sysrq_get_key_op(key);
        if (op_p) {
		/* Should we check for enabled operations (/proc/sysrq-trigger should not)
		 * and is the invoked operation enabled? */
		if (!check_mask || sysrq_enabled == 1 ||
		    (sysrq_enabled & op_p->enable_mask)) {
			printk ("%s\n", op_p->action_msg);
			console_loglevel = orig_log_level;
			op_p->handler(key, pt_regs, tty);
		}
		else
			printk("This sysrq operation is disabled.\n");
	} else {
		printk("HELP : ");
		/* Only print the help msg once per handler */
		for (i=0; i<SYSRQ_KEY_TABLE_LENGTH; i++) 
		if (sysrq_key_table[i]) {
			for (j=0; sysrq_key_table[i] != sysrq_key_table[j]; j++);
			if (j == i)
				printk ("%s ", sysrq_key_table[i]->help_msg);
		}
		printk ("\n");
		console_loglevel = orig_log_level;
	}
	spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
}

/*
 * This function is called by the keyboard handler when SysRq is pressed
 * and any other keycode arrives.
 */

void handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty)
{
	if (!sysrq_enabled)
		return;
	__handle_sysrq(key, pt_regs, tty, 1);
}

int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
                                struct sysrq_key_op *remove_op_p) {

	int retval;
	unsigned long flags;

	spin_lock_irqsave(&sysrq_key_table_lock, flags);
	if (__sysrq_get_key_op(key) == remove_op_p) {
		__sysrq_put_key_op(key, insert_op_p);
		retval = 0;
	} else {
		retval = -1;
	}
	spin_unlock_irqrestore(&sysrq_key_table_lock, flags);

	return retval;
}

int register_sysrq_key(int key, struct sysrq_key_op *op_p)
{
	return __sysrq_swap_key_ops(key, op_p, NULL);
}

int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
{
	return __sysrq_swap_key_ops(key, NULL, op_p);
}

EXPORT_SYMBOL(handle_sysrq);
EXPORT_SYMBOL(register_sysrq_key);
EXPORT_SYMBOL(unregister_sysrq_key);
Commit	Line	Data
1da177e4 LT	1	/* -- linux-c --
	2	*
	3	* $Id: sysrq.c,v 1.15 1998/08/23 14:56:41 mj Exp $
	4	*
	5	* Linux Magic System Request Key Hacks
	6	*
	7	* (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
	8	* based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz>
	9	*
	10	* (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
	11	* overhauled to use key registration
	12	* based upon discusions in irc://irc.openprojects.net/#kernelnewbies
	13	*/
	14
	15	#include <linux/config.h>
	16	#include <linux/sched.h>
	17	#include <linux/interrupt.h>
	18	#include <linux/mm.h>
	19	#include <linux/fs.h>
	20	#include <linux/tty.h>
	21	#include <linux/mount.h>
	22	#include <linux/kdev_t.h>
	23	#include <linux/major.h>
	24	#include <linux/reboot.h>
	25	#include <linux/sysrq.h>
	26	#include <linux/kbd_kern.h>
	27	#include <linux/quotaops.h>
	28	#include <linux/smp_lock.h>
	29	#include <linux/kernel.h>
	30	#include <linux/module.h>
	31	#include <linux/suspend.h>
	32	#include <linux/writeback.h>
	33	#include <linux/buffer_head.h> /* for fsync_bdev() */
	34	#include <linux/swap.h>
	35	#include <linux/spinlock.h>
	36	#include <linux/vt_kern.h>
	37	#include <linux/workqueue.h>
86b1ae38	38	#include <linux/kexec.h>
1da177e4 LT	39
	40	#include <asm/ptrace.h>
	41
	42	/* Whether we react on sysrq keys or just ignore them */
	43	int sysrq_enabled = 1;
	44
	45	/* Loglevel sysrq handler */
	46	static void sysrq_handle_loglevel(int key, struct pt_regs *pt_regs,
	47	struct tty_struct *tty)
	48	{
	49	int i;
	50	i = key - '0';
	51	console_loglevel = 7;
	52	printk("Loglevel set to %d\n", i);
	53	console_loglevel = i;
	54	}
	55	static struct sysrq_key_op sysrq_loglevel_op = {
	56	.handler = sysrq_handle_loglevel,
	57	.help_msg = "loglevel0-8",
	58	.action_msg = "Changing Loglevel",
	59	.enable_mask = SYSRQ_ENABLE_LOG,
	60	};
	61
	62
	63	/* SAK sysrq handler */
	64	#ifdef CONFIG_VT
	65	static void sysrq_handle_SAK(int key, struct pt_regs *pt_regs,
	66	struct tty_struct *tty)
	67	{
	68	if (tty)
	69	do_SAK(tty);
	70	reset_vc(vc_cons[fg_console].d);
	71	}
	72	static struct sysrq_key_op sysrq_SAK_op = {
	73	.handler = sysrq_handle_SAK,
	74	.help_msg = "saK",
	75	.action_msg = "SAK",
	76	.enable_mask = SYSRQ_ENABLE_KEYBOARD,
	77	};
	78	#endif
	79
	80	#ifdef CONFIG_VT
	81	/* unraw sysrq handler */
	82	static void sysrq_handle_unraw(int key, struct pt_regs *pt_regs,
	83	struct tty_struct *tty)
	84	{
	85	struct kbd_struct *kbd = &kbd_table[fg_console];
	86
	87	if (kbd)
	88	kbd->kbdmode = VC_XLATE;
	89	}
	90	static struct sysrq_key_op sysrq_unraw_op = {
	91	.handler = sysrq_handle_unraw,
	92	.help_msg = "unRaw",
	93	.action_msg = "Keyboard mode set to XLATE",
	94	.enable_mask = SYSRQ_ENABLE_KEYBOARD,
	95	};
	96	#endif /* CONFIG_VT */
	97
86b1ae38 HN	98	#ifdef CONFIG_KEXEC
	99	/* crashdump sysrq handler */
	100	static void sysrq_handle_crashdump(int key, struct pt_regs *pt_regs,
	101	struct tty_struct *tty)
	102	{
6e274d14	103	crash_kexec(pt_regs);
86b1ae38 HN	104	}
	105	static struct sysrq_key_op sysrq_crashdump_op = {
	106	.handler = sysrq_handle_crashdump,
	107	.help_msg = "Crashdump",
	108	.action_msg = "Trigger a crashdump",
	109	.enable_mask = SYSRQ_ENABLE_DUMP,
	110	};
	111	#endif
	112
1da177e4 LT	113	/* reboot sysrq handler */
	114	static void sysrq_handle_reboot(int key, struct pt_regs *pt_regs,
	115	struct tty_struct *tty)
	116	{
	117	local_irq_enable();
4de8b9b7	118	emergency_restart();
1da177e4 LT	119	}
	120
	121	static struct sysrq_key_op sysrq_reboot_op = {
	122	.handler = sysrq_handle_reboot,
	123	.help_msg = "reBoot",
	124	.action_msg = "Resetting",
	125	.enable_mask = SYSRQ_ENABLE_BOOT,
	126	};
	127
	128	static void sysrq_handle_sync(int key, struct pt_regs *pt_regs,
	129	struct tty_struct *tty)
	130	{
	131	emergency_sync();
	132	}
	133
	134	static struct sysrq_key_op sysrq_sync_op = {
	135	.handler = sysrq_handle_sync,
	136	.help_msg = "Sync",
	137	.action_msg = "Emergency Sync",
	138	.enable_mask = SYSRQ_ENABLE_SYNC,
	139	};
	140
	141	static void sysrq_handle_mountro(int key, struct pt_regs *pt_regs,
	142	struct tty_struct *tty)
	143	{
	144	emergency_remount();
	145	}
	146
	147	static struct sysrq_key_op sysrq_mountro_op = {
	148	.handler = sysrq_handle_mountro,
	149	.help_msg = "Unmount",
	150	.action_msg = "Emergency Remount R/O",
	151	.enable_mask = SYSRQ_ENABLE_REMOUNT,
	152	};
	153
	154	/* END SYNC SYSRQ HANDLERS BLOCK */
	155
	156
	157	/* SHOW SYSRQ HANDLERS BLOCK */
	158
	159	static void sysrq_handle_showregs(int key, struct pt_regs *pt_regs,
	160	struct tty_struct *tty)
	161	{
	162	if (pt_regs)
	163	show_regs(pt_regs);
	164	}
	165	static struct sysrq_key_op sysrq_showregs_op = {
	166	.handler = sysrq_handle_showregs,
	167	.help_msg = "showPc",
	168	.action_msg = "Show Regs",
	169	.enable_mask = SYSRQ_ENABLE_DUMP,
	170	};
	171
	172
	173	static void sysrq_handle_showstate(int key, struct pt_regs *pt_regs,
	174	struct tty_struct *tty)
	175	{
	176	show_state();
	177	}
	178	static struct sysrq_key_op sysrq_showstate_op = {
	179	.handler = sysrq_handle_showstate,
	180	.help_msg = "showTasks",
	181	.action_msg = "Show State",
	182	.enable_mask = SYSRQ_ENABLE_DUMP,
183	};
184
185
186	static void sysrq_handle_showmem(int key, struct pt_regs *pt_regs,
187	struct tty_struct *tty)
188	{
189	show_mem();
190	}
191	static struct sysrq_key_op sysrq_showmem_op = {
192	.handler = sysrq_handle_showmem,
193	.help_msg = "showMem",
194	.action_msg = "Show Memory",
195	.enable_mask = SYSRQ_ENABLE_DUMP,
196	};
197
198	/* SHOW SYSRQ HANDLERS BLOCK */
199
200
201	/* SIGNAL SYSRQ HANDLERS BLOCK */
202
203	/* signal sysrq helper function
204	* Sends a signal to all user processes */
205	static void send_sig_all(int sig)
206	{
207	struct task_struct *p;
208
209	for_each_process(p) {
210	if (p->mm && p->pid != 1)
211	/* Not swapper, init nor kernel thread */
212	force_sig(sig, p);
213	}
214	}
215
216	static void sysrq_handle_term(int key, struct pt_regs *pt_regs,
217	struct tty_struct *tty)
218	{
219	send_sig_all(SIGTERM);
220	console_loglevel = 8;
221	}
222	static struct sysrq_key_op sysrq_term_op = {
223	.handler = sysrq_handle_term,
224	.help_msg = "tErm",
225	.action_msg = "Terminate All Tasks",
226	.enable_mask = SYSRQ_ENABLE_SIGNAL,
227	};
228
229	static void moom_callback(void *ignored)
230	{
79b9ce31	231	out_of_memory(GFP_KERNEL, 0);
1da177e4 LT	232	}
	233
	234	static DECLARE_WORK(moom_work, moom_callback, NULL);
	235
	236	static void sysrq_handle_moom(int key, struct pt_regs *pt_regs,
	237	struct tty_struct *tty)
	238	{
	239	schedule_work(&moom_work);
	240	}
	241	static struct sysrq_key_op sysrq_moom_op = {
	242	.handler = sysrq_handle_moom,
	243	.help_msg = "Full",
	244	.action_msg = "Manual OOM execution",
	245	};
	246
	247	static void sysrq_handle_kill(int key, struct pt_regs *pt_regs,
	248	struct tty_struct *tty)
	249	{
	250	send_sig_all(SIGKILL);
	251	console_loglevel = 8;
	252	}
	253	static struct sysrq_key_op sysrq_kill_op = {
	254	.handler = sysrq_handle_kill,
	255	.help_msg = "kIll",
	256	.action_msg = "Kill All Tasks",
	257	.enable_mask = SYSRQ_ENABLE_SIGNAL,
	258	};
	259
	260	/* END SIGNAL SYSRQ HANDLERS BLOCK */
	261
	262	static void sysrq_handle_unrt(int key, struct pt_regs *pt_regs,
	263	struct tty_struct *tty)
	264	{
	265	normalize_rt_tasks();
	266	}
	267	static struct sysrq_key_op sysrq_unrt_op = {
	268	.handler = sysrq_handle_unrt,
	269	.help_msg = "Nice",
	270	.action_msg = "Nice All RT Tasks",
	271	.enable_mask = SYSRQ_ENABLE_RTNICE,
	272	};
	273
	274	/* Key Operations table and lock */
	275	static DEFINE_SPINLOCK(sysrq_key_table_lock);
	276	#define SYSRQ_KEY_TABLE_LENGTH 36
	277	static struct sysrq_key_op *sysrq_key_table[SYSRQ_KEY_TABLE_LENGTH] = {
	278	/* 0 */ &sysrq_loglevel_op,
	279	/* 1 */ &sysrq_loglevel_op,
	280	/* 2 */ &sysrq_loglevel_op,
	281	/* 3 */ &sysrq_loglevel_op,
	282	/* 4 */ &sysrq_loglevel_op,
	283	/* 5 */ &sysrq_loglevel_op,
	284	/* 6 */ &sysrq_loglevel_op,
	285	/* 7 */ &sysrq_loglevel_op,
	286	/* 8 */ &sysrq_loglevel_op,
	287	/* 9 */ &sysrq_loglevel_op,
	288	/* a / NULL, / Don't use for system provided sysrqs,
	289	it is handled specially on the sparc
	290	and will never arrive */
	291	/* b */ &sysrq_reboot_op,
86b1ae38 HN	292	#ifdef CONFIG_KEXEC
	293	/* c */ &sysrq_crashdump_op,
	294	#else
	295	/* c */ NULL,
	296	#endif
	297	/* d */ NULL,
1da177e4 LT	298	/* e */ &sysrq_term_op,
	299	/* f */ &sysrq_moom_op,
	300	/* g */ NULL,
	301	/* h */ NULL,
	302	/* i */ &sysrq_kill_op,
	303	/* j */ NULL,
	304	#ifdef CONFIG_VT
	305	/* k */ &sysrq_SAK_op,
	306	#else
	307	/* k */ NULL,
	308	#endif
	309	/* l */ NULL,
	310	/* m */ &sysrq_showmem_op,
	311	/* n */ &sysrq_unrt_op,
	312	/* o / NULL, / This will often be registered
	313	as 'Off' at init time */
	314	/* p */ &sysrq_showregs_op,
	315	/* q */ NULL,
	316	#ifdef CONFIG_VT
	317	/* r */ &sysrq_unraw_op,
	318	#else
	319	/* r */ NULL,
	320	#endif
	321	/* s */ &sysrq_sync_op,
	322	/* t */ &sysrq_showstate_op,
	323	/* u */ &sysrq_mountro_op,
	324	/* v / NULL, / May be assigned at init time by SMP VOYAGER */
	325	/* w */ NULL,
	326	/* x */ NULL,
	327	/* y */ NULL,
	328	/* z */ NULL
	329	};
	330
	331	/* key2index calculation, -1 on invalid index */
	332	static int sysrq_key_table_key2index(int key) {
	333	int retval;
	334	if ((key >= '0') && (key <= '9')) {
	335	retval = key - '0';
	336	} else if ((key >= 'a') && (key <= 'z')) {
	337	retval = key + 10 - 'a';
	338	} else {
	339	retval = -1;
	340	}
	341	return retval;
	342	}
	343
	344	/*
	345	* get and put functions for the table, exposed to modules.
	346	*/
	347
	348	struct sysrq_key_op *__sysrq_get_key_op (int key) {
	349	struct sysrq_key_op *op_p;
	350	int i;
	351
	352	i = sysrq_key_table_key2index(key);
	353	op_p = (i == -1) ? NULL : sysrq_key_table[i];
	354	return op_p;
	355	}
	356
	357	void __sysrq_put_key_op (int key, struct sysrq_key_op *op_p) {
	358	int i;
	359
	360	i = sysrq_key_table_key2index(key);
	361	if (i != -1)
362	sysrq_key_table[i] = op_p;
363	}
364
365	/*
366	* This is the non-locking version of handle_sysrq
367	* It must/can only be called by sysrq key handlers,
368	* as they are inside of the lock
369	*/
370
371	void __handle_sysrq(int key, struct pt_regs pt_regs, struct tty_struct tty, int check_mask)
372	{
373	struct sysrq_key_op *op_p;
374	int orig_log_level;
375	int i, j;
376	unsigned long flags;
377
378	spin_lock_irqsave(&sysrq_key_table_lock, flags);
379	orig_log_level = console_loglevel;
380	console_loglevel = 7;
381	printk(KERN_INFO "SysRq : ");
382
383	op_p = __sysrq_get_key_op(key);
384	if (op_p) {
385	/* Should we check for enabled operations (/proc/sysrq-trigger should not)
386	* and is the invoked operation enabled? */
387	if (!check_mask \|\| sysrq_enabled == 1 \|\|
388	(sysrq_enabled & op_p->enable_mask)) {
389	printk ("%s\n", op_p->action_msg);
390	console_loglevel = orig_log_level;
391	op_p->handler(key, pt_regs, tty);
392	}
393	else
394	printk("This sysrq operation is disabled.\n");
395	} else {
396	printk("HELP : ");
397	/* Only print the help msg once per handler */
398	for (i=0; i<SYSRQ_KEY_TABLE_LENGTH; i++)
399	if (sysrq_key_table[i]) {
400	for (j=0; sysrq_key_table[i] != sysrq_key_table[j]; j++);
401	if (j == i)
402	printk ("%s ", sysrq_key_table[i]->help_msg);
403	}
404	printk ("\n");
405	console_loglevel = orig_log_level;
406	}
407	spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
408	}
409
410	/*
411	* This function is called by the keyboard handler when SysRq is pressed
412	* and any other keycode arrives.
413	*/
414
415	void handle_sysrq(int key, struct pt_regs pt_regs, struct tty_struct tty)
416	{
417	if (!sysrq_enabled)
418	return;
419	__handle_sysrq(key, pt_regs, tty, 1);
420	}
421
422	int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
423	struct sysrq_key_op *remove_op_p) {
424
425	int retval;
426	unsigned long flags;
427
428	spin_lock_irqsave(&sysrq_key_table_lock, flags);
429	if (__sysrq_get_key_op(key) == remove_op_p) {
430	__sysrq_put_key_op(key, insert_op_p);
431	retval = 0;
432	} else {
433	retval = -1;
434	}
435	spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
436
437	return retval;
438	}
439
440	int register_sysrq_key(int key, struct sysrq_key_op *op_p)
441	{
442	return __sysrq_swap_key_ops(key, op_p, NULL);
443	}
444
445	int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
446	{
447	return __sysrq_swap_key_ops(key, NULL, op_p);
448	}
449
450	EXPORT_SYMBOL(handle_sysrq);
451	EXPORT_SYMBOL(register_sysrq_key);
452	EXPORT_SYMBOL(unregister_sysrq_key);