sysrq.c 14.9 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
/* -*- 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>
26
#include <linux/proc_fs.h>
27
#include <linux/nmi.h>
Linus Torvalds's avatar
Linus Torvalds committed
28
#include <linux/quotaops.h>
29
#include <linux/perf_event.h>
Linus Torvalds's avatar
Linus Torvalds committed
30 31 32 33 34 35 36 37 38
#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>
39
#include <linux/hrtimer.h>
40
#include <linux/oom.h>
41
#include <linux/slab.h>
Linus Torvalds's avatar
Linus Torvalds committed
42 43

#include <asm/ptrace.h>
44
#include <asm/irq_regs.h>
Linus Torvalds's avatar
Linus Torvalds committed
45 46

/* Whether we react on sysrq keys or just ignore them */
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 72 73 74
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
75

76
static void sysrq_handle_loglevel(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
77 78 79 80 81 82
{
	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
83
}
Linus Torvalds's avatar
Linus Torvalds committed
84 85
static struct sysrq_key_op sysrq_loglevel_op = {
	.handler	= sysrq_handle_loglevel,
86
	.help_msg	= "loglevel(0-9)",
Linus Torvalds's avatar
Linus Torvalds committed
87 88 89 90 91
	.action_msg	= "Changing Loglevel",
	.enable_mask	= SYSRQ_ENABLE_LOG,
};

#ifdef CONFIG_VT
92
static void sysrq_handle_SAK(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
93
{
94 95
	struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
	schedule_work(SAK_work);
Linus Torvalds's avatar
Linus Torvalds committed
96 97 98 99 100 101 102
}
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
103 104
#else
#define sysrq_SAK_op (*(struct sysrq_key_op *)0)
Linus Torvalds's avatar
Linus Torvalds committed
105 106 107
#endif

#ifdef CONFIG_VT
108
static void sysrq_handle_unraw(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
109 110 111 112
{
	struct kbd_struct *kbd = &kbd_table[fg_console];

	if (kbd)
Bill Nottingham's avatar
Bill Nottingham committed
113
		kbd->kbdmode = default_utf8 ? VC_UNICODE : VC_XLATE;
Linus Torvalds's avatar
Linus Torvalds committed
114 115 116 117
}
static struct sysrq_key_op sysrq_unraw_op = {
	.handler	= sysrq_handle_unraw,
	.help_msg	= "unRaw",
Bill Nottingham's avatar
Bill Nottingham committed
118
	.action_msg	= "Keyboard mode set to system default",
Linus Torvalds's avatar
Linus Torvalds committed
119 120
	.enable_mask	= SYSRQ_ENABLE_KEYBOARD,
};
Andrew Morton's avatar
Andrew Morton committed
121 122
#else
#define sysrq_unraw_op (*(struct sysrq_key_op *)0)
Linus Torvalds's avatar
Linus Torvalds committed
123 124
#endif /* CONFIG_VT */

125
static void sysrq_handle_crash(int key, struct tty_struct *tty)
126
{
127
	char *killer = NULL;
128 129 130

	panic_on_oops = 1;	/* force panic */
	wmb();
131
	*killer = 1;
132
}
133
static struct sysrq_key_op sysrq_crash_op = {
134 135 136
	.handler	= sysrq_handle_crash,
	.help_msg	= "Crash",
	.action_msg	= "Trigger a crash",
137 138 139
	.enable_mask	= SYSRQ_ENABLE_DUMP,
};

140
static void sysrq_handle_reboot(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
141
{
142
	lockdep_off();
Linus Torvalds's avatar
Linus Torvalds committed
143
	local_irq_enable();
144
	emergency_restart();
Linus Torvalds's avatar
Linus Torvalds committed
145 146 147 148 149 150 151 152
}
static struct sysrq_key_op sysrq_reboot_op = {
	.handler	= sysrq_handle_reboot,
	.help_msg	= "reBoot",
	.action_msg	= "Resetting",
	.enable_mask	= SYSRQ_ENABLE_BOOT,
};

153
static void sysrq_handle_sync(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
154 155 156 157 158 159 160 161 162 163
{
	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,
};

164 165 166 167 168 169 170 171
static void sysrq_handle_show_timers(int key, struct tty_struct *tty)
{
	sysrq_timer_list_show();
}

static struct sysrq_key_op sysrq_show_timers_op = {
	.handler	= sysrq_handle_show_timers,
	.help_msg	= "show-all-timers(Q)",
172
	.action_msg	= "Show clockevent devices & pending hrtimers (no others)",
173 174
};

175
static void sysrq_handle_mountro(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
176 177 178 179 180 181 182 183 184 185
{
	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,
};

186
#ifdef CONFIG_LOCKDEP
187
static void sysrq_handle_showlocks(int key, struct tty_struct *tty)
188
{
189
	debug_show_all_locks();
190
}
191

192 193 194 195 196
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
197 198
#else
#define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
199
#endif
Linus Torvalds's avatar
Linus Torvalds committed
200

201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219
#ifdef CONFIG_SMP
static DEFINE_SPINLOCK(show_lock);

static void showacpu(void *dummy)
{
	unsigned long flags;

	/* Idle CPUs have no interesting backtrace. */
	if (idle_cpu(smp_processor_id()))
		return;

	spin_lock_irqsave(&show_lock, flags);
	printk(KERN_INFO "CPU%d:\n", smp_processor_id());
	show_stack(NULL, NULL);
	spin_unlock_irqrestore(&show_lock, flags);
}

static void sysrq_showregs_othercpus(struct work_struct *dummy)
{
220
	smp_call_function(showacpu, NULL, 0);
221 222 223 224 225 226
}

static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);

static void sysrq_handle_showallcpus(int key, struct tty_struct *tty)
{
227 228 229 230 231 232 233 234 235 236 237 238 239 240
	/*
	 * Fall back to the workqueue based printing if the
	 * backtrace printing did not succeed or the
	 * architecture has no support for it:
	 */
	if (!trigger_all_cpu_backtrace()) {
		struct pt_regs *regs = get_irq_regs();

		if (regs) {
			printk(KERN_INFO "CPU%d:\n", smp_processor_id());
			show_regs(regs);
		}
		schedule_work(&sysrq_showallcpus);
	}
241 242 243 244
}

static struct sysrq_key_op sysrq_showallcpus_op = {
	.handler	= sysrq_handle_showallcpus,
245
	.help_msg	= "show-backtrace-all-active-cpus(L)",
246 247 248 249 250
	.action_msg	= "Show backtrace of all active CPUs",
	.enable_mask	= SYSRQ_ENABLE_DUMP,
};
#endif

251
static void sysrq_handle_showregs(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
252
{
253 254 255
	struct pt_regs *regs = get_irq_regs();
	if (regs)
		show_regs(regs);
256
	perf_event_print_debug();
Linus Torvalds's avatar
Linus Torvalds committed
257 258 259
}
static struct sysrq_key_op sysrq_showregs_op = {
	.handler	= sysrq_handle_showregs,
260
	.help_msg	= "show-registers(P)",
Linus Torvalds's avatar
Linus Torvalds committed
261 262 263 264
	.action_msg	= "Show Regs",
	.enable_mask	= SYSRQ_ENABLE_DUMP,
};

265
static void sysrq_handle_showstate(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
266 267 268 269 270
{
	show_state();
}
static struct sysrq_key_op sysrq_showstate_op = {
	.handler	= sysrq_handle_showstate,
271
	.help_msg	= "show-task-states(T)",
Linus Torvalds's avatar
Linus Torvalds committed
272 273 274 275
	.action_msg	= "Show State",
	.enable_mask	= SYSRQ_ENABLE_DUMP,
};

276 277 278 279 280 281
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,
282
	.help_msg	= "show-blocked-tasks(W)",
283 284 285 286
	.action_msg	= "Show Blocked State",
	.enable_mask	= SYSRQ_ENABLE_DUMP,
};

287 288 289 290 291 292 293 294 295
#ifdef CONFIG_TRACING
#include <linux/ftrace.h>

static void sysrq_ftrace_dump(int key, struct tty_struct *tty)
{
	ftrace_dump();
}
static struct sysrq_key_op sysrq_ftrace_dump_op = {
	.handler	= sysrq_ftrace_dump,
296
	.help_msg	= "dump-ftrace-buffer(Z)",
297 298 299 300 301 302
	.action_msg	= "Dump ftrace buffer",
	.enable_mask	= SYSRQ_ENABLE_DUMP,
};
#else
#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)0)
#endif
303

304
static void sysrq_handle_showmem(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
305 306 307 308 309
{
	show_mem();
}
static struct sysrq_key_op sysrq_showmem_op = {
	.handler	= sysrq_handle_showmem,
310
	.help_msg	= "show-memory-usage(M)",
Linus Torvalds's avatar
Linus Torvalds committed
311 312 313 314
	.action_msg	= "Show Memory",
	.enable_mask	= SYSRQ_ENABLE_DUMP,
};

Andrew Morton's avatar
Andrew Morton committed
315 316 317
/*
 * Signal sysrq helper function.  Sends a signal to all user processes.
 */
Linus Torvalds's avatar
Linus Torvalds committed
318 319 320 321 322
static void send_sig_all(int sig)
{
	struct task_struct *p;

	for_each_process(p) {
323
		if (p->mm && !is_global_init(p))
Linus Torvalds's avatar
Linus Torvalds committed
324 325 326 327 328
			/* Not swapper, init nor kernel thread */
			force_sig(sig, p);
	}
}

329
static void sysrq_handle_term(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
330 331 332 333 334 335
{
	send_sig_all(SIGTERM);
	console_loglevel = 8;
}
static struct sysrq_key_op sysrq_term_op = {
	.handler	= sysrq_handle_term,
336
	.help_msg	= "terminate-all-tasks(E)",
Linus Torvalds's avatar
Linus Torvalds committed
337 338 339 340
	.action_msg	= "Terminate All Tasks",
	.enable_mask	= SYSRQ_ENABLE_SIGNAL,
};

341
static void moom_callback(struct work_struct *ignored)
Linus Torvalds's avatar
Linus Torvalds committed
342
{
343
	out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0, NULL);
Linus Torvalds's avatar
Linus Torvalds committed
344 345
}

346
static DECLARE_WORK(moom_work, moom_callback);
Linus Torvalds's avatar
Linus Torvalds committed
347

348
static void sysrq_handle_moom(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
349 350 351 352 353
{
	schedule_work(&moom_work);
}
static struct sysrq_key_op sysrq_moom_op = {
	.handler	= sysrq_handle_moom,
354
	.help_msg	= "memory-full-oom-kill(F)",
Linus Torvalds's avatar
Linus Torvalds committed
355
	.action_msg	= "Manual OOM execution",
356
	.enable_mask	= SYSRQ_ENABLE_SIGNAL,
Linus Torvalds's avatar
Linus Torvalds committed
357 358
};

359 360 361 362 363 364 365 366 367 368 369 370 371
#ifdef CONFIG_BLOCK
static void sysrq_handle_thaw(int key, struct tty_struct *tty)
{
	emergency_thaw_all();
}
static struct sysrq_key_op sysrq_thaw_op = {
	.handler	= sysrq_handle_thaw,
	.help_msg	= "thaw-filesystems(J)",
	.action_msg	= "Emergency Thaw of all frozen filesystems",
	.enable_mask	= SYSRQ_ENABLE_SIGNAL,
};
#endif

372
static void sysrq_handle_kill(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
373 374 375 376 377 378
{
	send_sig_all(SIGKILL);
	console_loglevel = 8;
}
static struct sysrq_key_op sysrq_kill_op = {
	.handler	= sysrq_handle_kill,
379
	.help_msg	= "kill-all-tasks(I)",
Linus Torvalds's avatar
Linus Torvalds committed
380 381 382 383
	.action_msg	= "Kill All Tasks",
	.enable_mask	= SYSRQ_ENABLE_SIGNAL,
};

384
static void sysrq_handle_unrt(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
385 386 387 388 389
{
	normalize_rt_tasks();
}
static struct sysrq_key_op sysrq_unrt_op = {
	.handler	= sysrq_handle_unrt,
390
	.help_msg	= "nice-all-RT-tasks(N)",
Linus Torvalds's avatar
Linus Torvalds committed
391 392 393 394 395 396
	.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
397 398 399 400 401 402 403 404 405 406 407 408 409 410

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 */

	/*
411 412
	 * a: Don't use for system provided sysrqs, it is handled specially on
	 * sparc and will never arrive.
Andrew Morton's avatar
Andrew Morton committed
413 414 415
	 */
	NULL,				/* a */
	&sysrq_reboot_op,		/* b */
416
	&sysrq_crash_op,		/* c & ibm_emac driver debug */
Andrew Morton's avatar
Andrew Morton committed
417 418 419
	&sysrq_showlocks_op,		/* d */
	&sysrq_term_op,			/* e */
	&sysrq_moom_op,			/* f */
420
	/* g: May be registered for the kernel debugger */
Andrew Morton's avatar
Andrew Morton committed
421
	NULL,				/* g */
422
	NULL,				/* h - reserved for help */
Andrew Morton's avatar
Andrew Morton committed
423
	&sysrq_kill_op,			/* i */
424 425 426
#ifdef CONFIG_BLOCK
	&sysrq_thaw_op,			/* j */
#else
Andrew Morton's avatar
Andrew Morton committed
427
	NULL,				/* j */
428
#endif
Andrew Morton's avatar
Andrew Morton committed
429
	&sysrq_SAK_op,			/* k */
430 431 432
#ifdef CONFIG_SMP
	&sysrq_showallcpus_op,		/* l */
#else
Andrew Morton's avatar
Andrew Morton committed
433
	NULL,				/* l */
434
#endif
Andrew Morton's avatar
Andrew Morton committed
435 436
	&sysrq_showmem_op,		/* m */
	&sysrq_unrt_op,			/* n */
437
	/* o: This will often be registered as 'Off' at init time */
Andrew Morton's avatar
Andrew Morton committed
438 439
	NULL,				/* o */
	&sysrq_showregs_op,		/* p */
440
	&sysrq_show_timers_op,		/* q */
441
	&sysrq_unraw_op,		/* r */
Andrew Morton's avatar
Andrew Morton committed
442 443 444
	&sysrq_sync_op,			/* s */
	&sysrq_showstate_op,		/* t */
	&sysrq_mountro_op,		/* u */
445
	/* v: May be registered for frame buffer console restore */
Andrew Morton's avatar
Andrew Morton committed
446
	NULL,				/* v */
447 448 449
	&sysrq_showstate_blocked_op,	/* w */
	/* x: May be registered on ppc/powerpc for xmon */
	NULL,				/* x */
450
	/* y: May be registered on sparc64 for global register dump */
Andrew Morton's avatar
Andrew Morton committed
451
	NULL,				/* y */
452
	&sysrq_ftrace_dump_op,		/* z */
Linus Torvalds's avatar
Linus Torvalds committed
453 454 455
};

/* key2index calculation, -1 on invalid index */
Andrew Morton's avatar
Andrew Morton committed
456 457
static int sysrq_key_table_key2index(int key)
{
Linus Torvalds's avatar
Linus Torvalds committed
458
	int retval;
Andrew Morton's avatar
Andrew Morton committed
459 460

	if ((key >= '0') && (key <= '9'))
Linus Torvalds's avatar
Linus Torvalds committed
461
		retval = key - '0';
Andrew Morton's avatar
Andrew Morton committed
462
	else if ((key >= 'a') && (key <= 'z'))
Linus Torvalds's avatar
Linus Torvalds committed
463
		retval = key + 10 - 'a';
Andrew Morton's avatar
Andrew Morton committed
464
	else
Linus Torvalds's avatar
Linus Torvalds committed
465 466 467 468 469 470 471
		retval = -1;
	return retval;
}

/*
 * get and put functions for the table, exposed to modules.
 */
Andrew Morton's avatar
Andrew Morton committed
472 473 474
struct sysrq_key_op *__sysrq_get_key_op(int key)
{
        struct sysrq_key_op *op_p = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
475
        int i;
Andrew Morton's avatar
Andrew Morton committed
476

Linus Torvalds's avatar
Linus Torvalds committed
477
	i = sysrq_key_table_key2index(key);
Andrew Morton's avatar
Andrew Morton committed
478 479
	if (i != -1)
	        op_p = sysrq_key_table[i];
Linus Torvalds's avatar
Linus Torvalds committed
480 481 482
        return op_p;
}

Andrew Morton's avatar
Andrew Morton committed
483 484 485
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
486 487 488 489 490 491

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

/*
Andrew Morton's avatar
Andrew Morton committed
492 493
 * 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
494
 */
495
void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
Linus Torvalds's avatar
Linus Torvalds committed
496 497 498
{
	struct sysrq_key_op *op_p;
	int orig_log_level;
Andrew Morton's avatar
Andrew Morton committed
499
	int i;
Linus Torvalds's avatar
Linus Torvalds committed
500 501 502
	unsigned long flags;

	spin_lock_irqsave(&sysrq_key_table_lock, flags);
503 504 505 506 507 508
	/*
	 * Raise the apparent loglevel to maximum so that the sysrq header
	 * is shown to provide the user with positive feedback.  We do not
	 * simply emit this at KERN_EMERG as that would change message
	 * routing in the consumers of /proc/kmsg.
	 */
Linus Torvalds's avatar
Linus Torvalds committed
509 510 511 512 513 514
	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
515 516 517 518
		/*
		 * Should we check for enabled operations (/proc/sysrq-trigger
		 * should not) and is the invoked operation enabled?
		 */
519
		if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
Andrew Morton's avatar
Andrew Morton committed
520
			printk("%s\n", op_p->action_msg);
Linus Torvalds's avatar
Linus Torvalds committed
521
			console_loglevel = orig_log_level;
522
			op_p->handler(key, tty);
Andrew Morton's avatar
Andrew Morton committed
523
		} else {
Linus Torvalds's avatar
Linus Torvalds committed
524
			printk("This sysrq operation is disabled.\n");
Andrew Morton's avatar
Andrew Morton committed
525
		}
Linus Torvalds's avatar
Linus Torvalds committed
526 527 528
	} else {
		printk("HELP : ");
		/* Only print the help msg once per handler */
Andrew Morton's avatar
Andrew Morton committed
529 530 531 532 533 534 535 536 537 538 539
		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
540
		}
Andrew Morton's avatar
Andrew Morton committed
541
		printk("\n");
Linus Torvalds's avatar
Linus Torvalds committed
542 543 544 545 546 547 548 549 550
		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.
 */
551
void handle_sysrq(int key, struct tty_struct *tty)
Linus Torvalds's avatar
Linus Torvalds committed
552
{
553 554
	if (sysrq_on())
		__handle_sysrq(key, tty, 1);
Linus Torvalds's avatar
Linus Torvalds committed
555
}
Andrew Morton's avatar
Andrew Morton committed
556
EXPORT_SYMBOL(handle_sysrq);
Linus Torvalds's avatar
Linus Torvalds committed
557

558
static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
Andrew Morton's avatar
Andrew Morton committed
559 560
                                struct sysrq_key_op *remove_op_p)
{
Linus Torvalds's avatar
Linus Torvalds committed
561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579

	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
580
EXPORT_SYMBOL(register_sysrq_key);
Linus Torvalds's avatar
Linus Torvalds committed
581 582 583 584 585 586

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);
587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615

#ifdef CONFIG_PROC_FS
/*
 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
 */
static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
				   size_t count, loff_t *ppos)
{
	if (count) {
		char c;

		if (get_user(c, buf))
			return -EFAULT;
		__handle_sysrq(c, NULL, 0);
	}
	return count;
}

static const struct file_operations proc_sysrq_trigger_operations = {
	.write		= write_sysrq_trigger,
};

static int __init sysrq_init(void)
{
	proc_create("sysrq-trigger", S_IWUSR, NULL, &proc_sysrq_trigger_operations);
	return 0;
}
module_init(sysrq_init);
#endif