sysrq.c 10.8 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>
Linus Torvalds's avatar
Linus Torvalds committed
38 39 40 41 42 43 44

#include <asm/ptrace.h>

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

static void sysrq_handle_loglevel(int key, struct pt_regs *pt_regs,
Andrew Morton's avatar
Andrew Morton committed
45
				  struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
46 47 48 49 50 51
{
	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
52
}
Linus Torvalds's avatar
Linus Torvalds committed
53 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
static void sysrq_handle_SAK(int key, struct pt_regs *pt_regs,
Andrew Morton's avatar
Andrew Morton committed
62
			     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 79
#endif

#ifdef CONFIG_VT
static void sysrq_handle_unraw(int key, struct pt_regs *pt_regs,
Andrew Morton's avatar
Andrew Morton committed
80
			       struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
81 82 83 84 85 86 87 88 89 90 91 92
{
	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
93 94
#else
#define sysrq_unraw_op (*(struct sysrq_key_op *)0)
Linus Torvalds's avatar
Linus Torvalds committed
95 96
#endif /* CONFIG_VT */

97 98 99 100
#ifdef CONFIG_KEXEC
static void sysrq_handle_crashdump(int key, struct pt_regs *pt_regs,
				struct tty_struct *tty)
{
101
	crash_kexec(pt_regs);
102 103 104 105 106 107 108
}
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
109 110
#else
#define sysrq_crashdump_op (*(struct sysrq_key_op *)0)
111 112
#endif

Linus Torvalds's avatar
Linus Torvalds committed
113
static void sysrq_handle_reboot(int key, struct pt_regs *pt_regs,
Andrew Morton's avatar
Andrew Morton committed
114
				struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
115 116
{
	local_irq_enable();
117
	emergency_restart();
Linus Torvalds's avatar
Linus Torvalds committed
118 119 120 121 122 123 124 125 126
}
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,
Andrew Morton's avatar
Andrew Morton committed
127
			      struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
128 129 130 131 132 133 134 135 136 137 138
{
	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,
Andrew Morton's avatar
Andrew Morton committed
139
				 struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
140 141 142 143 144 145 146 147 148 149
{
	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,
};

150
#ifdef CONFIG_DEBUG_MUTEXES
Andrew Morton's avatar
Andrew Morton committed
151 152
static void sysrq_handle_showlocks(int key, struct pt_regs *pt_regs,
				struct tty_struct *tty)
153 154 155 156 157 158 159 160
{
	mutex_debug_show_all_locks();
}
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
161 162
#else
#define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
163
#endif
Linus Torvalds's avatar
Linus Torvalds committed
164 165

static void sysrq_handle_showregs(int key, struct pt_regs *pt_regs,
Andrew Morton's avatar
Andrew Morton committed
166
				  struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
167 168 169 170 171 172 173 174 175 176 177 178
{
	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,
Andrew Morton's avatar
Andrew Morton committed
179
				   struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
180 181 182 183 184 185 186 187 188 189 190
{
	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,
Andrew Morton's avatar
Andrew Morton committed
191
				 struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
192 193 194 195 196 197 198 199 200 201
{
	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
202 203 204
/*
 * Signal sysrq helper function.  Sends a signal to all user processes.
 */
Linus Torvalds's avatar
Linus Torvalds committed
205 206 207 208 209 210 211 212 213 214 215 216
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,
Andrew Morton's avatar
Andrew Morton committed
217
			      struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
218 219 220 221 222 223 224 225 226 227 228 229 230
{
	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
231 232
	out_of_memory(&NODE_DATA(0)->node_zonelists[ZONE_NORMAL],
			GFP_KERNEL, 0);
Linus Torvalds's avatar
Linus Torvalds committed
233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248
}

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,
Andrew Morton's avatar
Andrew Morton committed
249
			      struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274
{
	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,
};

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);
Andrew Morton's avatar
Andrew Morton committed
275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319

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
320 321 322
};

/* key2index calculation, -1 on invalid index */
Andrew Morton's avatar
Andrew Morton committed
323 324
static int sysrq_key_table_key2index(int key)
{
Linus Torvalds's avatar
Linus Torvalds committed
325
	int retval;
Andrew Morton's avatar
Andrew Morton committed
326 327

	if ((key >= '0') && (key <= '9'))
Linus Torvalds's avatar
Linus Torvalds committed
328
		retval = key - '0';
Andrew Morton's avatar
Andrew Morton committed
329
	else if ((key >= 'a') && (key <= 'z'))
Linus Torvalds's avatar
Linus Torvalds committed
330
		retval = key + 10 - 'a';
Andrew Morton's avatar
Andrew Morton committed
331
	else
Linus Torvalds's avatar
Linus Torvalds committed
332 333 334 335 336 337 338
		retval = -1;
	return retval;
}

/*
 * get and put functions for the table, exposed to modules.
 */
Andrew Morton's avatar
Andrew Morton committed
339 340 341
struct sysrq_key_op *__sysrq_get_key_op(int key)
{
        struct sysrq_key_op *op_p = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
342
        int i;
Andrew Morton's avatar
Andrew Morton committed
343

Linus Torvalds's avatar
Linus Torvalds committed
344
	i = sysrq_key_table_key2index(key);
Andrew Morton's avatar
Andrew Morton committed
345 346
	if (i != -1)
	        op_p = sysrq_key_table[i];
Linus Torvalds's avatar
Linus Torvalds committed
347 348 349
        return op_p;
}

Andrew Morton's avatar
Andrew Morton committed
350 351 352
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
353 354 355 356 357 358

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

/*
Andrew Morton's avatar
Andrew Morton committed
359 360
 * 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
361
 */
Andrew Morton's avatar
Andrew Morton committed
362 363
void __handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty,
			int check_mask)
Linus Torvalds's avatar
Linus Torvalds committed
364 365 366
{
	struct sysrq_key_op *op_p;
	int orig_log_level;
Andrew Morton's avatar
Andrew Morton committed
367
	int i;
Linus Torvalds's avatar
Linus Torvalds committed
368 369 370 371 372 373 374 375 376
	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
377 378 379 380
		/*
		 * Should we check for enabled operations (/proc/sysrq-trigger
		 * should not) and is the invoked operation enabled?
		 */
Linus Torvalds's avatar
Linus Torvalds committed
381 382
		if (!check_mask || sysrq_enabled == 1 ||
		    (sysrq_enabled & op_p->enable_mask)) {
Andrew Morton's avatar
Andrew Morton committed
383
			printk("%s\n", op_p->action_msg);
Linus Torvalds's avatar
Linus Torvalds committed
384 385
			console_loglevel = orig_log_level;
			op_p->handler(key, pt_regs, tty);
Andrew Morton's avatar
Andrew Morton committed
386
		} else {
Linus Torvalds's avatar
Linus Torvalds committed
387
			printk("This sysrq operation is disabled.\n");
Andrew Morton's avatar
Andrew Morton committed
388
		}
Linus Torvalds's avatar
Linus Torvalds committed
389 390 391
	} else {
		printk("HELP : ");
		/* Only print the help msg once per handler */
Andrew Morton's avatar
Andrew Morton committed
392 393 394 395 396 397 398 399 400 401 402
		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
403
		}
Andrew Morton's avatar
Andrew Morton committed
404
		printk("\n");
Linus Torvalds's avatar
Linus Torvalds committed
405 406 407 408 409 410 411 412 413 414 415 416 417 418 419
		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);
}
Andrew Morton's avatar
Andrew Morton committed
420
EXPORT_SYMBOL(handle_sysrq);
Linus Torvalds's avatar
Linus Torvalds committed
421

422
static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
Andrew Morton's avatar
Andrew Morton committed
423 424
                                struct sysrq_key_op *remove_op_p)
{
Linus Torvalds's avatar
Linus Torvalds committed
425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443

	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
444
EXPORT_SYMBOL(register_sysrq_key);
Linus Torvalds's avatar
Linus Torvalds committed
445 446 447 448 449 450

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);