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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* -*- linux-c -*-
2 *
3 * $Id: sysrq.c,v 1.15 1998/08/23 14:56:41 mj Exp $
4 *
5 * Linux Magic System Request Key Hacks
6 *
7 * (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
8 * based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz>
9 *
10 * (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
11 * overhauled to use key registration
12 * based upon discusions in irc://irc.openprojects.net/#kernelnewbies
13 */
14
Linus Torvalds1da177e2005-04-16 15:20:36 -070015#include <linux/sched.h>
16#include <linux/interrupt.h>
17#include <linux/mm.h>
18#include <linux/fs.h>
19#include <linux/tty.h>
20#include <linux/mount.h>
21#include <linux/kdev_t.h>
22#include <linux/major.h>
23#include <linux/reboot.h>
24#include <linux/sysrq.h>
25#include <linux/kbd_kern.h>
26#include <linux/quotaops.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070027#include <linux/kernel.h>
28#include <linux/module.h>
29#include <linux/suspend.h>
30#include <linux/writeback.h>
31#include <linux/buffer_head.h> /* for fsync_bdev() */
32#include <linux/swap.h>
33#include <linux/spinlock.h>
34#include <linux/vt_kern.h>
35#include <linux/workqueue.h>
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -070036#include <linux/kexec.h>
David Howells7d12e782006-10-05 14:55:46 +010037#include <linux/irq.h>
Ingo Molnar88ad0bf62007-02-16 01:28:16 -080038#include <linux/hrtimer.h>
David Rientjes5a3135c22007-10-16 23:25:53 -070039#include <linux/oom.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070040
41#include <asm/ptrace.h>
Heiko Carstens2033b0c2006-10-06 16:38:42 +020042#include <asm/irq_regs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
44/* Whether we react on sysrq keys or just ignore them */
Ingo Molnar5d6f6472006-12-13 00:34:36 -080045int __read_mostly __sysrq_enabled = 1;
46
47static int __read_mostly sysrq_always_enabled;
48
49int sysrq_on(void)
50{
51 return __sysrq_enabled || sysrq_always_enabled;
52}
53
54/*
55 * A value of 1 means 'all', other nonzero values are an op mask:
56 */
57static inline int sysrq_on_mask(int mask)
58{
59 return sysrq_always_enabled || __sysrq_enabled == 1 ||
60 (__sysrq_enabled & mask);
61}
62
63static int __init sysrq_always_enabled_setup(char *str)
64{
65 sysrq_always_enabled = 1;
66 printk(KERN_INFO "debug: sysrq always enabled.\n");
67
68 return 1;
69}
70
71__setup("sysrq_always_enabled", sysrq_always_enabled_setup);
72
Linus Torvalds1da177e2005-04-16 15:20:36 -070073
David Howells7d12e782006-10-05 14:55:46 +010074static void sysrq_handle_loglevel(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -070075{
76 int i;
77 i = key - '0';
78 console_loglevel = 7;
79 printk("Loglevel set to %d\n", i);
80 console_loglevel = i;
Andrew Mortonbf36b902006-03-25 03:07:08 -080081}
Linus Torvalds1da177e2005-04-16 15:20:36 -070082static struct sysrq_key_op sysrq_loglevel_op = {
83 .handler = sysrq_handle_loglevel,
84 .help_msg = "loglevel0-8",
85 .action_msg = "Changing Loglevel",
86 .enable_mask = SYSRQ_ENABLE_LOG,
87};
88
Linus Torvalds1da177e2005-04-16 15:20:36 -070089#ifdef CONFIG_VT
David Howells7d12e782006-10-05 14:55:46 +010090static void sysrq_handle_SAK(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -070091{
Eric W. Biederman8b6312f2007-02-10 01:44:34 -080092 struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
Eric W. Biederman8b6312f2007-02-10 01:44:34 -080093 schedule_work(SAK_work);
Linus Torvalds1da177e2005-04-16 15:20:36 -070094}
95static struct sysrq_key_op sysrq_SAK_op = {
96 .handler = sysrq_handle_SAK,
97 .help_msg = "saK",
98 .action_msg = "SAK",
99 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
100};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800101#else
102#define sysrq_SAK_op (*(struct sysrq_key_op *)0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103#endif
104
105#ifdef CONFIG_VT
David Howells7d12e782006-10-05 14:55:46 +0100106static void sysrq_handle_unraw(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107{
108 struct kbd_struct *kbd = &kbd_table[fg_console];
109
110 if (kbd)
Bill Nottingham2e8ecb92007-10-16 23:29:38 -0700111 kbd->kbdmode = default_utf8 ? VC_UNICODE : VC_XLATE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112}
113static struct sysrq_key_op sysrq_unraw_op = {
114 .handler = sysrq_handle_unraw,
115 .help_msg = "unRaw",
Bill Nottingham2e8ecb92007-10-16 23:29:38 -0700116 .action_msg = "Keyboard mode set to system default",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
118};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800119#else
120#define sysrq_unraw_op (*(struct sysrq_key_op *)0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121#endif /* CONFIG_VT */
122
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700123#ifdef CONFIG_KEXEC
David Howells7d12e782006-10-05 14:55:46 +0100124static void sysrq_handle_crashdump(int key, struct tty_struct *tty)
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700125{
David Howells7d12e782006-10-05 14:55:46 +0100126 crash_kexec(get_irq_regs());
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700127}
128static struct sysrq_key_op sysrq_crashdump_op = {
129 .handler = sysrq_handle_crashdump,
130 .help_msg = "Crashdump",
131 .action_msg = "Trigger a crashdump",
132 .enable_mask = SYSRQ_ENABLE_DUMP,
133};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800134#else
135#define sysrq_crashdump_op (*(struct sysrq_key_op *)0)
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700136#endif
137
David Howells7d12e782006-10-05 14:55:46 +0100138static void sysrq_handle_reboot(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139{
Peter Zijlstrab2e9c7d2006-09-30 23:28:02 -0700140 lockdep_off();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 local_irq_enable();
Eric W. Biederman4de8b9b2005-07-26 11:51:06 -0600142 emergency_restart();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144static struct sysrq_key_op sysrq_reboot_op = {
145 .handler = sysrq_handle_reboot,
146 .help_msg = "reBoot",
147 .action_msg = "Resetting",
148 .enable_mask = SYSRQ_ENABLE_BOOT,
149};
150
David Howells7d12e782006-10-05 14:55:46 +0100151static void sysrq_handle_sync(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152{
153 emergency_sync();
154}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155static struct sysrq_key_op sysrq_sync_op = {
156 .handler = sysrq_handle_sync,
157 .help_msg = "Sync",
158 .action_msg = "Emergency Sync",
159 .enable_mask = SYSRQ_ENABLE_SYNC,
160};
161
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800162static void sysrq_handle_show_timers(int key, struct tty_struct *tty)
163{
164 sysrq_timer_list_show();
165}
166
167static struct sysrq_key_op sysrq_show_timers_op = {
168 .handler = sysrq_handle_show_timers,
169 .help_msg = "show-all-timers(Q)",
170 .action_msg = "Show Pending Timers",
171};
172
David Howells7d12e782006-10-05 14:55:46 +0100173static void sysrq_handle_mountro(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174{
175 emergency_remount();
176}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177static struct sysrq_key_op sysrq_mountro_op = {
178 .handler = sysrq_handle_mountro,
179 .help_msg = "Unmount",
180 .action_msg = "Emergency Remount R/O",
181 .enable_mask = SYSRQ_ENABLE_REMOUNT,
182};
183
Ingo Molnar8c645802006-07-03 00:24:56 -0700184#ifdef CONFIG_LOCKDEP
David Howells7d12e782006-10-05 14:55:46 +0100185static void sysrq_handle_showlocks(int key, struct tty_struct *tty)
Ingo Molnarde5097c2006-01-09 15:59:21 -0800186{
Ingo Molnar9a11b49a2006-07-03 00:24:33 -0700187 debug_show_all_locks();
Ingo Molnarde5097c2006-01-09 15:59:21 -0800188}
Ingo Molnar8c645802006-07-03 00:24:56 -0700189
Ingo Molnarde5097c2006-01-09 15:59:21 -0800190static struct sysrq_key_op sysrq_showlocks_op = {
191 .handler = sysrq_handle_showlocks,
192 .help_msg = "show-all-locks(D)",
193 .action_msg = "Show Locks Held",
194};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800195#else
196#define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
Ingo Molnarde5097c2006-01-09 15:59:21 -0800197#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198
Rik van Riel5045bca2008-04-29 00:59:21 -0700199#ifdef CONFIG_SMP
200static DEFINE_SPINLOCK(show_lock);
201
202static void showacpu(void *dummy)
203{
204 unsigned long flags;
205
206 /* Idle CPUs have no interesting backtrace. */
207 if (idle_cpu(smp_processor_id()))
208 return;
209
210 spin_lock_irqsave(&show_lock, flags);
211 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
212 show_stack(NULL, NULL);
213 spin_unlock_irqrestore(&show_lock, flags);
214}
215
216static void sysrq_showregs_othercpus(struct work_struct *dummy)
217{
218 smp_call_function(showacpu, NULL, 0, 0);
219}
220
221static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
222
223static void sysrq_handle_showallcpus(int key, struct tty_struct *tty)
224{
225 struct pt_regs *regs = get_irq_regs();
226 if (regs) {
227 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
228 show_regs(regs);
229 }
230 schedule_work(&sysrq_showallcpus);
231}
232
233static struct sysrq_key_op sysrq_showallcpus_op = {
234 .handler = sysrq_handle_showallcpus,
235 .help_msg = "aLlcpus",
236 .action_msg = "Show backtrace of all active CPUs",
237 .enable_mask = SYSRQ_ENABLE_DUMP,
238};
239#endif
240
David Howells7d12e782006-10-05 14:55:46 +0100241static void sysrq_handle_showregs(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242{
David Howells7d12e782006-10-05 14:55:46 +0100243 struct pt_regs *regs = get_irq_regs();
244 if (regs)
245 show_regs(regs);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246}
247static struct sysrq_key_op sysrq_showregs_op = {
248 .handler = sysrq_handle_showregs,
249 .help_msg = "showPc",
250 .action_msg = "Show Regs",
251 .enable_mask = SYSRQ_ENABLE_DUMP,
252};
253
David Howells7d12e782006-10-05 14:55:46 +0100254static void sysrq_handle_showstate(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255{
256 show_state();
257}
258static struct sysrq_key_op sysrq_showstate_op = {
259 .handler = sysrq_handle_showstate,
260 .help_msg = "showTasks",
261 .action_msg = "Show State",
262 .enable_mask = SYSRQ_ENABLE_DUMP,
263};
264
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800265static void sysrq_handle_showstate_blocked(int key, struct tty_struct *tty)
266{
267 show_state_filter(TASK_UNINTERRUPTIBLE);
268}
269static struct sysrq_key_op sysrq_showstate_blocked_op = {
270 .handler = sysrq_handle_showstate_blocked,
Randy Dunlapd346cce2007-01-31 23:48:17 -0800271 .help_msg = "shoW-blocked-tasks",
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800272 .action_msg = "Show Blocked State",
273 .enable_mask = SYSRQ_ENABLE_DUMP,
274};
275
276
David Howells7d12e782006-10-05 14:55:46 +0100277static void sysrq_handle_showmem(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278{
279 show_mem();
280}
281static struct sysrq_key_op sysrq_showmem_op = {
282 .handler = sysrq_handle_showmem,
283 .help_msg = "showMem",
284 .action_msg = "Show Memory",
285 .enable_mask = SYSRQ_ENABLE_DUMP,
286};
287
Andrew Mortonbf36b902006-03-25 03:07:08 -0800288/*
289 * Signal sysrq helper function. Sends a signal to all user processes.
290 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291static void send_sig_all(int sig)
292{
293 struct task_struct *p;
294
295 for_each_process(p) {
Serge E. Hallynb460cbc2007-10-18 23:39:52 -0700296 if (p->mm && !is_global_init(p))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297 /* Not swapper, init nor kernel thread */
298 force_sig(sig, p);
299 }
300}
301
David Howells7d12e782006-10-05 14:55:46 +0100302static void sysrq_handle_term(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303{
304 send_sig_all(SIGTERM);
305 console_loglevel = 8;
306}
307static struct sysrq_key_op sysrq_term_op = {
308 .handler = sysrq_handle_term,
309 .help_msg = "tErm",
310 .action_msg = "Terminate All Tasks",
311 .enable_mask = SYSRQ_ENABLE_SIGNAL,
312};
313
David Howells65f27f32006-11-22 14:55:48 +0000314static void moom_callback(struct work_struct *ignored)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315{
Mel Gorman0e884602008-04-28 02:12:14 -0700316 out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317}
318
David Howells65f27f32006-11-22 14:55:48 +0000319static DECLARE_WORK(moom_work, moom_callback);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320
David Howells7d12e782006-10-05 14:55:46 +0100321static void sysrq_handle_moom(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322{
323 schedule_work(&moom_work);
324}
325static struct sysrq_key_op sysrq_moom_op = {
326 .handler = sysrq_handle_moom,
327 .help_msg = "Full",
328 .action_msg = "Manual OOM execution",
329};
330
David Howells7d12e782006-10-05 14:55:46 +0100331static void sysrq_handle_kill(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332{
333 send_sig_all(SIGKILL);
334 console_loglevel = 8;
335}
336static struct sysrq_key_op sysrq_kill_op = {
337 .handler = sysrq_handle_kill,
338 .help_msg = "kIll",
339 .action_msg = "Kill All Tasks",
340 .enable_mask = SYSRQ_ENABLE_SIGNAL,
341};
342
David Howells7d12e782006-10-05 14:55:46 +0100343static void sysrq_handle_unrt(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344{
345 normalize_rt_tasks();
346}
347static struct sysrq_key_op sysrq_unrt_op = {
348 .handler = sysrq_handle_unrt,
349 .help_msg = "Nice",
350 .action_msg = "Nice All RT Tasks",
351 .enable_mask = SYSRQ_ENABLE_RTNICE,
352};
353
354/* Key Operations table and lock */
355static DEFINE_SPINLOCK(sysrq_key_table_lock);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800356
357static struct sysrq_key_op *sysrq_key_table[36] = {
358 &sysrq_loglevel_op, /* 0 */
359 &sysrq_loglevel_op, /* 1 */
360 &sysrq_loglevel_op, /* 2 */
361 &sysrq_loglevel_op, /* 3 */
362 &sysrq_loglevel_op, /* 4 */
363 &sysrq_loglevel_op, /* 5 */
364 &sysrq_loglevel_op, /* 6 */
365 &sysrq_loglevel_op, /* 7 */
366 &sysrq_loglevel_op, /* 8 */
367 &sysrq_loglevel_op, /* 9 */
368
369 /*
Randy Dunlapd346cce2007-01-31 23:48:17 -0800370 * a: Don't use for system provided sysrqs, it is handled specially on
371 * sparc and will never arrive.
Andrew Mortonbf36b902006-03-25 03:07:08 -0800372 */
373 NULL, /* a */
374 &sysrq_reboot_op, /* b */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800375 &sysrq_crashdump_op, /* c & ibm_emac driver debug */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800376 &sysrq_showlocks_op, /* d */
377 &sysrq_term_op, /* e */
378 &sysrq_moom_op, /* f */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800379 /* g: May be registered by ppc for kgdb */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800380 NULL, /* g */
381 NULL, /* h */
382 &sysrq_kill_op, /* i */
383 NULL, /* j */
384 &sysrq_SAK_op, /* k */
Rik van Riel5045bca2008-04-29 00:59:21 -0700385#ifdef CONFIG_SMP
386 &sysrq_showallcpus_op, /* l */
387#else
Andrew Mortonbf36b902006-03-25 03:07:08 -0800388 NULL, /* l */
Rik van Riel5045bca2008-04-29 00:59:21 -0700389#endif
Andrew Mortonbf36b902006-03-25 03:07:08 -0800390 &sysrq_showmem_op, /* m */
391 &sysrq_unrt_op, /* n */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800392 /* o: This will often be registered as 'Off' at init time */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800393 NULL, /* o */
394 &sysrq_showregs_op, /* p */
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800395 &sysrq_show_timers_op, /* q */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800396 &sysrq_unraw_op, /* r */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800397 &sysrq_sync_op, /* s */
398 &sysrq_showstate_op, /* t */
399 &sysrq_mountro_op, /* u */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800400 /* v: May be registered at init time by SMP VOYAGER */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800401 NULL, /* v */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800402 &sysrq_showstate_blocked_op, /* w */
403 /* x: May be registered on ppc/powerpc for xmon */
404 NULL, /* x */
David S. Miller93dae5b2008-05-19 23:46:00 -0700405 /* y: May be registered on sparc64 for global register dump */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800406 NULL, /* y */
407 NULL /* z */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408};
409
410/* key2index calculation, -1 on invalid index */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800411static int sysrq_key_table_key2index(int key)
412{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 int retval;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800414
415 if ((key >= '0') && (key <= '9'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 retval = key - '0';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800417 else if ((key >= 'a') && (key <= 'z'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 retval = key + 10 - 'a';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800419 else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420 retval = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421 return retval;
422}
423
424/*
425 * get and put functions for the table, exposed to modules.
426 */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800427struct sysrq_key_op *__sysrq_get_key_op(int key)
428{
429 struct sysrq_key_op *op_p = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430 int i;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800431
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 i = sysrq_key_table_key2index(key);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800433 if (i != -1)
434 op_p = sysrq_key_table[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435 return op_p;
436}
437
Andrew Mortonbf36b902006-03-25 03:07:08 -0800438static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
439{
440 int i = sysrq_key_table_key2index(key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442 if (i != -1)
443 sysrq_key_table[i] = op_p;
444}
445
446/*
Andrew Mortonbf36b902006-03-25 03:07:08 -0800447 * This is the non-locking version of handle_sysrq. It must/can only be called
448 * by sysrq key handlers, as they are inside of the lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700449 */
David Howells7d12e782006-10-05 14:55:46 +0100450void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700451{
452 struct sysrq_key_op *op_p;
453 int orig_log_level;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800454 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455 unsigned long flags;
456
457 spin_lock_irqsave(&sysrq_key_table_lock, flags);
458 orig_log_level = console_loglevel;
459 console_loglevel = 7;
460 printk(KERN_INFO "SysRq : ");
461
462 op_p = __sysrq_get_key_op(key);
463 if (op_p) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800464 /*
465 * Should we check for enabled operations (/proc/sysrq-trigger
466 * should not) and is the invoked operation enabled?
467 */
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800468 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800469 printk("%s\n", op_p->action_msg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470 console_loglevel = orig_log_level;
David Howells7d12e782006-10-05 14:55:46 +0100471 op_p->handler(key, tty);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800472 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473 printk("This sysrq operation is disabled.\n");
Andrew Mortonbf36b902006-03-25 03:07:08 -0800474 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475 } else {
476 printk("HELP : ");
477 /* Only print the help msg once per handler */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800478 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
479 if (sysrq_key_table[i]) {
480 int j;
481
482 for (j = 0; sysrq_key_table[i] !=
483 sysrq_key_table[j]; j++)
484 ;
485 if (j != i)
486 continue;
487 printk("%s ", sysrq_key_table[i]->help_msg);
488 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700489 }
Andrew Mortonbf36b902006-03-25 03:07:08 -0800490 printk("\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491 console_loglevel = orig_log_level;
492 }
493 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
494}
495
496/*
497 * This function is called by the keyboard handler when SysRq is pressed
498 * and any other keycode arrives.
499 */
David Howells7d12e782006-10-05 14:55:46 +0100500void handle_sysrq(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501{
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800502 if (sysrq_on())
503 __handle_sysrq(key, tty, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800505EXPORT_SYMBOL(handle_sysrq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506
Adrian Bunkcf62ddc2005-11-08 21:39:47 -0800507static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
Andrew Mortonbf36b902006-03-25 03:07:08 -0800508 struct sysrq_key_op *remove_op_p)
509{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510
511 int retval;
512 unsigned long flags;
513
514 spin_lock_irqsave(&sysrq_key_table_lock, flags);
515 if (__sysrq_get_key_op(key) == remove_op_p) {
516 __sysrq_put_key_op(key, insert_op_p);
517 retval = 0;
518 } else {
519 retval = -1;
520 }
521 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522 return retval;
523}
524
525int register_sysrq_key(int key, struct sysrq_key_op *op_p)
526{
527 return __sysrq_swap_key_ops(key, op_p, NULL);
528}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800529EXPORT_SYMBOL(register_sysrq_key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530
531int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
532{
533 return __sysrq_swap_key_ops(key, NULL, op_p);
534}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535EXPORT_SYMBOL(unregister_sysrq_key);