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
	lockdep_off();
Linus Torvalds's avatar
Linus Torvalds committed
117
	local_irq_enable();
118
	emergency_restart();
Linus Torvalds's avatar
Linus Torvalds committed
119 120 121 122 123 124 125 126 127
}
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
128
			      struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
129 130 131 132 133 134 135 136 137 138 139
{
	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
140
				 struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
141 142 143 144 145 146 147 148 149 150
{
	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,
};

151
#ifdef CONFIG_LOCKDEP
Andrew Morton's avatar
Andrew Morton committed
152 153
static void sysrq_handle_showlocks(int key, struct pt_regs *pt_regs,
				struct tty_struct *tty)
154
{
155
	debug_show_all_locks();
156
}
157

158 159 160 161 162
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
163 164
#else
#define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
165
#endif
Linus Torvalds's avatar
Linus Torvalds committed
166 167

static void sysrq_handle_showregs(int key, struct pt_regs *pt_regs,
Andrew Morton's avatar
Andrew Morton committed
168
				  struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
169 170 171 172 173 174 175 176 177 178 179 180
{
	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
181
				   struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
182 183 184 185 186 187 188 189 190 191 192
{
	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
193
				 struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
194 195 196 197 198 199 200 201 202 203
{
	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
204 205 206
/*
 * Signal sysrq helper function.  Sends a signal to all user processes.
 */
Linus Torvalds's avatar
Linus Torvalds committed
207 208 209 210 211
static void send_sig_all(int sig)
{
	struct task_struct *p;

	for_each_process(p) {
212
		if (p->mm && !is_init(p))
Linus Torvalds's avatar
Linus Torvalds committed
213 214 215 216 217 218
			/* 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
219
			      struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
220 221 222 223 224 225 226 227 228 229 230 231 232
{
	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
233 234
	out_of_memory(&NODE_DATA(0)->node_zonelists[ZONE_NORMAL],
			GFP_KERNEL, 0);
Linus Torvalds's avatar
Linus Torvalds committed
235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250
}

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
251
			      struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276
{
	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
277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321

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
322 323 324
};

/* key2index calculation, -1 on invalid index */
Andrew Morton's avatar
Andrew Morton committed
325 326
static int sysrq_key_table_key2index(int key)
{
Linus Torvalds's avatar
Linus Torvalds committed
327
	int retval;
Andrew Morton's avatar
Andrew Morton committed
328 329

	if ((key >= '0') && (key <= '9'))
Linus Torvalds's avatar
Linus Torvalds committed
330
		retval = key - '0';
Andrew Morton's avatar
Andrew Morton committed
331
	else if ((key >= 'a') && (key <= 'z'))
Linus Torvalds's avatar
Linus Torvalds committed
332
		retval = key + 10 - 'a';
Andrew Morton's avatar
Andrew Morton committed
333
	else
Linus Torvalds's avatar
Linus Torvalds committed
334 335 336 337 338 339 340
		retval = -1;
	return retval;
}

/*
 * get and put functions for the table, exposed to modules.
 */
Andrew Morton's avatar
Andrew Morton committed
341 342 343
struct sysrq_key_op *__sysrq_get_key_op(int key)
{
        struct sysrq_key_op *op_p = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
344
        int i;
Andrew Morton's avatar
Andrew Morton committed
345

Linus Torvalds's avatar
Linus Torvalds committed
346
	i = sysrq_key_table_key2index(key);
Andrew Morton's avatar
Andrew Morton committed
347 348
	if (i != -1)
	        op_p = sysrq_key_table[i];
Linus Torvalds's avatar
Linus Torvalds committed
349 350 351
        return op_p;
}

Andrew Morton's avatar
Andrew Morton committed
352 353 354
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
355 356 357 358 359 360

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

/*
Andrew Morton's avatar
Andrew Morton committed
361 362
 * 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
363
 */
Andrew Morton's avatar
Andrew Morton committed
364 365
void __handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty,
			int check_mask)
Linus Torvalds's avatar
Linus Torvalds committed
366 367 368
{
	struct sysrq_key_op *op_p;
	int orig_log_level;
Andrew Morton's avatar
Andrew Morton committed
369
	int i;
Linus Torvalds's avatar
Linus Torvalds committed
370 371 372 373 374 375 376 377 378
	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
379 380 381 382
		/*
		 * Should we check for enabled operations (/proc/sysrq-trigger
		 * should not) and is the invoked operation enabled?
		 */
Linus Torvalds's avatar
Linus Torvalds committed
383 384
		if (!check_mask || sysrq_enabled == 1 ||
		    (sysrq_enabled & op_p->enable_mask)) {
Andrew Morton's avatar
Andrew Morton committed
385
			printk("%s\n", op_p->action_msg);
Linus Torvalds's avatar
Linus Torvalds committed
386 387
			console_loglevel = orig_log_level;
			op_p->handler(key, pt_regs, tty);
Andrew Morton's avatar
Andrew Morton committed
388
		} else {
Linus Torvalds's avatar
Linus Torvalds committed
389
			printk("This sysrq operation is disabled.\n");
Andrew Morton's avatar
Andrew Morton committed
390
		}
Linus Torvalds's avatar
Linus Torvalds committed
391 392 393
	} else {
		printk("HELP : ");
		/* Only print the help msg once per handler */
Andrew Morton's avatar
Andrew Morton committed
394 395 396 397 398 399 400 401 402 403 404
		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
405
		}
Andrew Morton's avatar
Andrew Morton committed
406
		printk("\n");
Linus Torvalds's avatar
Linus Torvalds committed
407 408 409 410 411 412 413 414 415 416 417 418 419 420 421
		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
422
EXPORT_SYMBOL(handle_sysrq);
Linus Torvalds's avatar
Linus Torvalds committed
423

424
static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
Andrew Morton's avatar
Andrew Morton committed
425 426
                                struct sysrq_key_op *remove_op_p)
{
Linus Torvalds's avatar
Linus Torvalds committed
427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445

	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
446
EXPORT_SYMBOL(register_sysrq_key);
Linus Torvalds's avatar
Linus Torvalds committed
447 448 449 450 451 452

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);