sysrq.c 10.4 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
/* -*- 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/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>
37
#include <linux/kexec.h>
38
#include <linux/irq.h>
Linus Torvalds's avatar
Linus Torvalds committed
39 40

#include <asm/ptrace.h>
41
#include <asm/irq_regs.h>
Linus Torvalds's avatar
Linus Torvalds committed
42 43 44 45

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

46
static void sysrq_handle_loglevel(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
47 48 49 50 51 52
{
	int i;
	i = key - '0';
	console_loglevel = 7;
	printk("Loglevel set to %d\n", i);
	console_loglevel = i;
Andrew Morton's avatar
Andrew Morton committed
53
}
Linus Torvalds's avatar
Linus Torvalds committed
54 55 56 57 58 59 60 61
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,
};

#ifdef CONFIG_VT
62
static void sysrq_handle_SAK(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
63 64 65 66 67 68 69 70 71 72 73
{
	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,
};
Andrew Morton's avatar
Andrew Morton committed
74 75
#else
#define sysrq_SAK_op (*(struct sysrq_key_op *)0)
Linus Torvalds's avatar
Linus Torvalds committed
76 77 78
#endif

#ifdef CONFIG_VT
79
static void sysrq_handle_unraw(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
80 81 82 83 84 85 86 87 88 89 90 91
{
	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,
};
Andrew Morton's avatar
Andrew Morton committed
92 93
#else
#define sysrq_unraw_op (*(struct sysrq_key_op *)0)
Linus Torvalds's avatar
Linus Torvalds committed
94 95
#endif /* CONFIG_VT */

96
#ifdef CONFIG_KEXEC
97
static void sysrq_handle_crashdump(int key, struct tty_struct *tty)
98
{
99
	crash_kexec(get_irq_regs());
100 101 102 103 104 105 106
}
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,
};
Andrew Morton's avatar
Andrew Morton committed
107 108
#else
#define sysrq_crashdump_op (*(struct sysrq_key_op *)0)
109 110
#endif

111
static void sysrq_handle_reboot(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
112
{
113
	lockdep_off();
Linus Torvalds's avatar
Linus Torvalds committed
114
	local_irq_enable();
115
	emergency_restart();
Linus Torvalds's avatar
Linus Torvalds committed
116 117 118 119 120 121 122 123
}
static struct sysrq_key_op sysrq_reboot_op = {
	.handler	= sysrq_handle_reboot,
	.help_msg	= "reBoot",
	.action_msg	= "Resetting",
	.enable_mask	= SYSRQ_ENABLE_BOOT,
};

124
static void sysrq_handle_sync(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
125 126 127 128 129 130 131 132 133 134
{
	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,
};

135
static void sysrq_handle_mountro(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
136 137 138 139 140 141 142 143 144 145
{
	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,
};

146
#ifdef CONFIG_LOCKDEP
147
static void sysrq_handle_showlocks(int key, struct tty_struct *tty)
148
{
149
	debug_show_all_locks();
150
}
151

152 153 154 155 156
static struct sysrq_key_op sysrq_showlocks_op = {
	.handler	= sysrq_handle_showlocks,
	.help_msg	= "show-all-locks(D)",
	.action_msg	= "Show Locks Held",
};
Andrew Morton's avatar
Andrew Morton committed
157 158
#else
#define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
159
#endif
Linus Torvalds's avatar
Linus Torvalds committed
160

161
static void sysrq_handle_showregs(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
162
{
163 164 165
	struct pt_regs *regs = get_irq_regs();
	if (regs)
		show_regs(regs);
Linus Torvalds's avatar
Linus Torvalds committed
166 167 168 169 170 171 172 173
}
static struct sysrq_key_op sysrq_showregs_op = {
	.handler	= sysrq_handle_showregs,
	.help_msg	= "showPc",
	.action_msg	= "Show Regs",
	.enable_mask	= SYSRQ_ENABLE_DUMP,
};

174
static void sysrq_handle_showstate(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
175 176 177 178 179 180 181 182 183 184
{
	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,
};

185
static void sysrq_handle_showmem(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
186 187 188 189 190 191 192 193 194 195
{
	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,
};

Andrew Morton's avatar
Andrew Morton committed
196 197 198
/*
 * Signal sysrq helper function.  Sends a signal to all user processes.
 */
Linus Torvalds's avatar
Linus Torvalds committed
199 200 201 202 203
static void send_sig_all(int sig)
{
	struct task_struct *p;

	for_each_process(p) {
204
		if (p->mm && !is_init(p))
Linus Torvalds's avatar
Linus Torvalds committed
205 206 207 208 209
			/* Not swapper, init nor kernel thread */
			force_sig(sig, p);
	}
}

210
static void sysrq_handle_term(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
211 212 213 214 215 216 217 218 219 220 221 222 223
{
	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)
{
Andrew Morton's avatar
Andrew Morton committed
224 225
	out_of_memory(&NODE_DATA(0)->node_zonelists[ZONE_NORMAL],
			GFP_KERNEL, 0);
Linus Torvalds's avatar
Linus Torvalds committed
226 227 228 229
}

static DECLARE_WORK(moom_work, moom_callback, NULL);

230
static void sysrq_handle_moom(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
231 232 233 234 235 236 237 238 239
{
	schedule_work(&moom_work);
}
static struct sysrq_key_op sysrq_moom_op = {
	.handler	= sysrq_handle_moom,
	.help_msg	= "Full",
	.action_msg	= "Manual OOM execution",
};

240
static void sysrq_handle_kill(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
241 242 243 244 245 246 247 248 249 250 251
{
	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,
};

252
static void sysrq_handle_unrt(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
253 254 255 256 257 258 259 260 261 262 263 264
{
	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);
Andrew Morton's avatar
Andrew Morton committed
265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309

static struct sysrq_key_op *sysrq_key_table[36] = {
	&sysrq_loglevel_op,		/* 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 */

	/*
	 * Don't use for system provided sysrqs, it is handled specially on
	 * sparc and will never arrive
	 */
	NULL,				/* a */
	&sysrq_reboot_op,		/* b */
	&sysrq_crashdump_op,		/* c */
	&sysrq_showlocks_op,		/* d */
	&sysrq_term_op,			/* e */
	&sysrq_moom_op,			/* f */
	NULL,				/* g */
	NULL,				/* h */
	&sysrq_kill_op,			/* i */
	NULL,				/* j */
	&sysrq_SAK_op,			/* k */
	NULL,				/* l */
	&sysrq_showmem_op,		/* m */
	&sysrq_unrt_op,			/* n */
	/* This will often be registered as 'Off' at init time */
	NULL,				/* o */
	&sysrq_showregs_op,		/* p */
	NULL,				/* q */
	&sysrq_unraw_op,			/* r */
	&sysrq_sync_op,			/* s */
	&sysrq_showstate_op,		/* t */
	&sysrq_mountro_op,		/* u */
	/* May be assigned at init time by SMP VOYAGER */
	NULL,				/* v */
	NULL,				/* w */
	NULL,				/* x */
	NULL,				/* y */
	NULL				/* z */
Linus Torvalds's avatar
Linus Torvalds committed
310 311 312
};

/* key2index calculation, -1 on invalid index */
Andrew Morton's avatar
Andrew Morton committed
313 314
static int sysrq_key_table_key2index(int key)
{
Linus Torvalds's avatar
Linus Torvalds committed
315
	int retval;
Andrew Morton's avatar
Andrew Morton committed
316 317

	if ((key >= '0') && (key <= '9'))
Linus Torvalds's avatar
Linus Torvalds committed
318
		retval = key - '0';
Andrew Morton's avatar
Andrew Morton committed
319
	else if ((key >= 'a') && (key <= 'z'))
Linus Torvalds's avatar
Linus Torvalds committed
320
		retval = key + 10 - 'a';
Andrew Morton's avatar
Andrew Morton committed
321
	else
Linus Torvalds's avatar
Linus Torvalds committed
322 323 324 325 326 327 328
		retval = -1;
	return retval;
}

/*
 * get and put functions for the table, exposed to modules.
 */
Andrew Morton's avatar
Andrew Morton committed
329 330 331
struct sysrq_key_op *__sysrq_get_key_op(int key)
{
        struct sysrq_key_op *op_p = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
332
        int i;
Andrew Morton's avatar
Andrew Morton committed
333

Linus Torvalds's avatar
Linus Torvalds committed
334
	i = sysrq_key_table_key2index(key);
Andrew Morton's avatar
Andrew Morton committed
335 336
	if (i != -1)
	        op_p = sysrq_key_table[i];
Linus Torvalds's avatar
Linus Torvalds committed
337 338 339
        return op_p;
}

Andrew Morton's avatar
Andrew Morton committed
340 341 342
static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
{
        int i = sysrq_key_table_key2index(key);
Linus Torvalds's avatar
Linus Torvalds committed
343 344 345 346 347 348

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

/*
Andrew Morton's avatar
Andrew Morton committed
349 350
 * 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
Linus Torvalds's avatar
Linus Torvalds committed
351
 */
352
void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
Linus Torvalds's avatar
Linus Torvalds committed
353 354 355
{
	struct sysrq_key_op *op_p;
	int orig_log_level;
Andrew Morton's avatar
Andrew Morton committed
356
	int i;
Linus Torvalds's avatar
Linus Torvalds committed
357 358 359 360 361 362 363 364 365
	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) {
Andrew Morton's avatar
Andrew Morton committed
366 367 368 369
		/*
		 * Should we check for enabled operations (/proc/sysrq-trigger
		 * should not) and is the invoked operation enabled?
		 */
Linus Torvalds's avatar
Linus Torvalds committed
370 371
		if (!check_mask || sysrq_enabled == 1 ||
		    (sysrq_enabled & op_p->enable_mask)) {
Andrew Morton's avatar
Andrew Morton committed
372
			printk("%s\n", op_p->action_msg);
Linus Torvalds's avatar
Linus Torvalds committed
373
			console_loglevel = orig_log_level;
374
			op_p->handler(key, tty);
Andrew Morton's avatar
Andrew Morton committed
375
		} else {
Linus Torvalds's avatar
Linus Torvalds committed
376
			printk("This sysrq operation is disabled.\n");
Andrew Morton's avatar
Andrew Morton committed
377
		}
Linus Torvalds's avatar
Linus Torvalds committed
378 379 380
	} else {
		printk("HELP : ");
		/* Only print the help msg once per handler */
Andrew Morton's avatar
Andrew Morton committed
381 382 383 384 385 386 387 388 389 390 391
		for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
			if (sysrq_key_table[i]) {
				int j;

				for (j = 0; sysrq_key_table[i] !=
						sysrq_key_table[j]; j++)
					;
				if (j != i)
					continue;
				printk("%s ", sysrq_key_table[i]->help_msg);
			}
Linus Torvalds's avatar
Linus Torvalds committed
392
		}
Andrew Morton's avatar
Andrew Morton committed
393
		printk("\n");
Linus Torvalds's avatar
Linus Torvalds committed
394 395 396 397 398 399 400 401 402
		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.
 */
403
void handle_sysrq(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
404 405 406
{
	if (!sysrq_enabled)
		return;
407
	__handle_sysrq(key, tty, 1);
Linus Torvalds's avatar
Linus Torvalds committed
408
}
Andrew Morton's avatar
Andrew Morton committed
409
EXPORT_SYMBOL(handle_sysrq);
Linus Torvalds's avatar
Linus Torvalds committed
410

411
static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
Andrew Morton's avatar
Andrew Morton committed
412 413
                                struct sysrq_key_op *remove_op_p)
{
Linus Torvalds's avatar
Linus Torvalds committed
414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432

	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);
}
Andrew Morton's avatar
Andrew Morton committed
433
EXPORT_SYMBOL(register_sysrq_key);
Linus Torvalds's avatar
Linus Torvalds committed
434 435 436 437 438 439

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