sysrq.c 11.2 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

/* Whether we react on sysrq keys or just ignore them */
44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71
int __read_mostly __sysrq_enabled = 1;

static int __read_mostly sysrq_always_enabled;

int sysrq_on(void)
{
	return __sysrq_enabled || sysrq_always_enabled;
}

/*
 * A value of 1 means 'all', other nonzero values are an op mask:
 */
static inline int sysrq_on_mask(int mask)
{
	return sysrq_always_enabled || __sysrq_enabled == 1 ||
						(__sysrq_enabled & mask);
}

static int __init sysrq_always_enabled_setup(char *str)
{
	sysrq_always_enabled = 1;
	printk(KERN_INFO "debug: sysrq always enabled.\n");

	return 1;
}

__setup("sysrq_always_enabled", sysrq_always_enabled_setup);

Linus Torvalds's avatar
Linus Torvalds committed
72

73
static void sysrq_handle_loglevel(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
74 75 76 77 78 79
{
	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
80
}
Linus Torvalds's avatar
Linus Torvalds committed
81 82 83 84 85 86 87 88
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
89
static void sysrq_handle_SAK(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
90 91 92 93 94 95 96 97 98 99 100
{
	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
101 102
#else
#define sysrq_SAK_op (*(struct sysrq_key_op *)0)
Linus Torvalds's avatar
Linus Torvalds committed
103 104 105
#endif

#ifdef CONFIG_VT
106
static void sysrq_handle_unraw(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
107 108 109 110 111 112 113 114 115 116 117 118
{
	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
119 120
#else
#define sysrq_unraw_op (*(struct sysrq_key_op *)0)
Linus Torvalds's avatar
Linus Torvalds committed
121 122
#endif /* CONFIG_VT */

123
#ifdef CONFIG_KEXEC
124
static void sysrq_handle_crashdump(int key, struct tty_struct *tty)
125
{
126
	crash_kexec(get_irq_regs());
127 128 129 130 131 132 133
}
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
134 135
#else
#define sysrq_crashdump_op (*(struct sysrq_key_op *)0)
136 137
#endif

138
static void sysrq_handle_reboot(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
139
{
140
	lockdep_off();
Linus Torvalds's avatar
Linus Torvalds committed
141
	local_irq_enable();
142
	emergency_restart();
Linus Torvalds's avatar
Linus Torvalds committed
143 144 145 146 147 148 149 150
}
static struct sysrq_key_op sysrq_reboot_op = {
	.handler	= sysrq_handle_reboot,
	.help_msg	= "reBoot",
	.action_msg	= "Resetting",
	.enable_mask	= SYSRQ_ENABLE_BOOT,
};

151
static void sysrq_handle_sync(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
152 153 154 155 156 157 158 159 160 161
{
	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,
};

162
static void sysrq_handle_mountro(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
163 164 165 166 167 168 169 170 171 172
{
	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,
};

173
#ifdef CONFIG_LOCKDEP
174
static void sysrq_handle_showlocks(int key, struct tty_struct *tty)
175
{
176
	debug_show_all_locks();
177
}
178

179 180 181 182 183
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
184 185
#else
#define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
186
#endif
Linus Torvalds's avatar
Linus Torvalds committed
187

188
static void sysrq_handle_showregs(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
189
{
190 191 192
	struct pt_regs *regs = get_irq_regs();
	if (regs)
		show_regs(regs);
Linus Torvalds's avatar
Linus Torvalds committed
193 194 195 196 197 198 199 200
}
static struct sysrq_key_op sysrq_showregs_op = {
	.handler	= sysrq_handle_showregs,
	.help_msg	= "showPc",
	.action_msg	= "Show Regs",
	.enable_mask	= SYSRQ_ENABLE_DUMP,
};

201
static void sysrq_handle_showstate(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
202 203 204 205 206 207 208 209 210 211
{
	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,
};

212 213 214 215 216 217 218 219 220 221 222 223
static void sysrq_handle_showstate_blocked(int key, struct tty_struct *tty)
{
	show_state_filter(TASK_UNINTERRUPTIBLE);
}
static struct sysrq_key_op sysrq_showstate_blocked_op = {
	.handler	= sysrq_handle_showstate_blocked,
	.help_msg	= "showBlockedTasks",
	.action_msg	= "Show Blocked State",
	.enable_mask	= SYSRQ_ENABLE_DUMP,
};


224
static void sysrq_handle_showmem(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
225 226 227 228 229 230 231 232 233 234
{
	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
235 236 237
/*
 * Signal sysrq helper function.  Sends a signal to all user processes.
 */
Linus Torvalds's avatar
Linus Torvalds committed
238 239 240 241 242
static void send_sig_all(int sig)
{
	struct task_struct *p;

	for_each_process(p) {
243
		if (p->mm && !is_init(p))
Linus Torvalds's avatar
Linus Torvalds committed
244 245 246 247 248
			/* Not swapper, init nor kernel thread */
			force_sig(sig, p);
	}
}

249
static void sysrq_handle_term(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
250 251 252 253 254 255 256 257 258 259 260
{
	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,
};

261
static void moom_callback(struct work_struct *ignored)
Linus Torvalds's avatar
Linus Torvalds committed
262
{
Andrew Morton's avatar
Andrew Morton committed
263 264
	out_of_memory(&NODE_DATA(0)->node_zonelists[ZONE_NORMAL],
			GFP_KERNEL, 0);
Linus Torvalds's avatar
Linus Torvalds committed
265 266
}

267
static DECLARE_WORK(moom_work, moom_callback);
Linus Torvalds's avatar
Linus Torvalds committed
268

269
static void sysrq_handle_moom(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
270 271 272 273 274 275 276 277 278
{
	schedule_work(&moom_work);
}
static struct sysrq_key_op sysrq_moom_op = {
	.handler	= sysrq_handle_moom,
	.help_msg	= "Full",
	.action_msg	= "Manual OOM execution",
};

279
static void sysrq_handle_kill(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
280 281 282 283 284 285 286 287 288 289 290
{
	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,
};

291
static void sysrq_handle_unrt(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
292 293 294 295 296 297 298 299 300 301 302 303
{
	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
304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345

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 */
346
	&sysrq_showstate_blocked_op,	/* x */
Andrew Morton's avatar
Andrew Morton committed
347 348
	NULL,				/* y */
	NULL				/* z */
Linus Torvalds's avatar
Linus Torvalds committed
349 350 351
};

/* key2index calculation, -1 on invalid index */
Andrew Morton's avatar
Andrew Morton committed
352 353
static int sysrq_key_table_key2index(int key)
{
Linus Torvalds's avatar
Linus Torvalds committed
354
	int retval;
Andrew Morton's avatar
Andrew Morton committed
355 356

	if ((key >= '0') && (key <= '9'))
Linus Torvalds's avatar
Linus Torvalds committed
357
		retval = key - '0';
Andrew Morton's avatar
Andrew Morton committed
358
	else if ((key >= 'a') && (key <= 'z'))
Linus Torvalds's avatar
Linus Torvalds committed
359
		retval = key + 10 - 'a';
Andrew Morton's avatar
Andrew Morton committed
360
	else
Linus Torvalds's avatar
Linus Torvalds committed
361 362 363 364 365 366 367
		retval = -1;
	return retval;
}

/*
 * get and put functions for the table, exposed to modules.
 */
Andrew Morton's avatar
Andrew Morton committed
368 369 370
struct sysrq_key_op *__sysrq_get_key_op(int key)
{
        struct sysrq_key_op *op_p = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
371
        int i;
Andrew Morton's avatar
Andrew Morton committed
372

Linus Torvalds's avatar
Linus Torvalds committed
373
	i = sysrq_key_table_key2index(key);
Andrew Morton's avatar
Andrew Morton committed
374 375
	if (i != -1)
	        op_p = sysrq_key_table[i];
Linus Torvalds's avatar
Linus Torvalds committed
376 377 378
        return op_p;
}

Andrew Morton's avatar
Andrew Morton committed
379 380 381
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
382 383 384 385 386 387

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

/*
Andrew Morton's avatar
Andrew Morton committed
388 389
 * 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
390
 */
391
void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
Linus Torvalds's avatar
Linus Torvalds committed
392 393 394
{
	struct sysrq_key_op *op_p;
	int orig_log_level;
Andrew Morton's avatar
Andrew Morton committed
395
	int i;
Linus Torvalds's avatar
Linus Torvalds committed
396 397 398 399 400 401 402 403 404
	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
405 406 407 408
		/*
		 * Should we check for enabled operations (/proc/sysrq-trigger
		 * should not) and is the invoked operation enabled?
		 */
409
		if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
Andrew Morton's avatar
Andrew Morton committed
410
			printk("%s\n", op_p->action_msg);
Linus Torvalds's avatar
Linus Torvalds committed
411
			console_loglevel = orig_log_level;
412
			op_p->handler(key, tty);
Andrew Morton's avatar
Andrew Morton committed
413
		} else {
Linus Torvalds's avatar
Linus Torvalds committed
414
			printk("This sysrq operation is disabled.\n");
Andrew Morton's avatar
Andrew Morton committed
415
		}
Linus Torvalds's avatar
Linus Torvalds committed
416 417 418
	} else {
		printk("HELP : ");
		/* Only print the help msg once per handler */
Andrew Morton's avatar
Andrew Morton committed
419 420 421 422 423 424 425 426 427 428 429
		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
430
		}
Andrew Morton's avatar
Andrew Morton committed
431
		printk("\n");
Linus Torvalds's avatar
Linus Torvalds committed
432 433 434 435 436 437 438 439 440
		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.
 */
441
void handle_sysrq(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
442
{
443 444
	if (sysrq_on())
		__handle_sysrq(key, tty, 1);
Linus Torvalds's avatar
Linus Torvalds committed
445
}
Andrew Morton's avatar
Andrew Morton committed
446
EXPORT_SYMBOL(handle_sysrq);
Linus Torvalds's avatar
Linus Torvalds committed
447

448
static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
Andrew Morton's avatar
Andrew Morton committed
449 450
                                struct sysrq_key_op *remove_op_p)
{
Linus Torvalds's avatar
Linus Torvalds committed
451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469

	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
470
EXPORT_SYMBOL(register_sysrq_key);
Linus Torvalds's avatar
Linus Torvalds committed
471 472 473 474 475 476

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);