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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>
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -070026#include <linux/proc_fs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070027#include <linux/quotaops.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070028#include <linux/kernel.h>
29#include <linux/module.h>
30#include <linux/suspend.h>
31#include <linux/writeback.h>
32#include <linux/buffer_head.h> /* for fsync_bdev() */
33#include <linux/swap.h>
34#include <linux/spinlock.h>
35#include <linux/vt_kern.h>
36#include <linux/workqueue.h>
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -070037#include <linux/kexec.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,
Randy Dunlap208b95c2009-01-06 14:41:13 -080084 .help_msg = "loglevel(0-9)",
Linus Torvalds1da177e2005-04-16 15:20:36 -070085 .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)",
Thomas Gleixner322acf62008-10-20 12:33:14 +0200170 .action_msg = "Show clockevent devices & pending hrtimers (no others)",
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800171};
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{
Ingo Molnar8b604d52008-06-27 11:52:45 +0200218 smp_call_function(showacpu, NULL, 0);
Rik van Riel5045bca2008-04-29 00:59:21 -0700219}
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,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800235 .help_msg = "show-backtrace-all-active-cpus(L)",
Rik van Riel5045bca2008-04-29 00:59:21 -0700236 .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,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800249 .help_msg = "show-registers(P)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250 .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,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800260 .help_msg = "show-task-states(T)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261 .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 Dunlap208b95c2009-01-06 14:41:13 -0800271 .help_msg = "show-blocked-tasks(W)",
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800272 .action_msg = "Show Blocked State",
273 .enable_mask = SYSRQ_ENABLE_DUMP,
274};
275
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100276#ifdef CONFIG_TRACING
277#include <linux/ftrace.h>
278
279static void sysrq_ftrace_dump(int key, struct tty_struct *tty)
280{
281 ftrace_dump();
282}
283static struct sysrq_key_op sysrq_ftrace_dump_op = {
284 .handler = sysrq_ftrace_dump,
Randy Dunlap3871f2f2008-12-24 16:06:57 -0800285 .help_msg = "dump-ftrace-buffer(Z)",
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100286 .action_msg = "Dump ftrace buffer",
287 .enable_mask = SYSRQ_ENABLE_DUMP,
288};
289#else
290#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)0)
291#endif
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800292
David Howells7d12e782006-10-05 14:55:46 +0100293static void sysrq_handle_showmem(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294{
295 show_mem();
296}
297static struct sysrq_key_op sysrq_showmem_op = {
298 .handler = sysrq_handle_showmem,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800299 .help_msg = "show-memory-usage(M)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 .action_msg = "Show Memory",
301 .enable_mask = SYSRQ_ENABLE_DUMP,
302};
303
Andrew Mortonbf36b902006-03-25 03:07:08 -0800304/*
305 * Signal sysrq helper function. Sends a signal to all user processes.
306 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307static void send_sig_all(int sig)
308{
309 struct task_struct *p;
310
311 for_each_process(p) {
Serge E. Hallynb460cbc2007-10-18 23:39:52 -0700312 if (p->mm && !is_global_init(p))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313 /* Not swapper, init nor kernel thread */
314 force_sig(sig, p);
315 }
316}
317
David Howells7d12e782006-10-05 14:55:46 +0100318static void sysrq_handle_term(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319{
320 send_sig_all(SIGTERM);
321 console_loglevel = 8;
322}
323static struct sysrq_key_op sysrq_term_op = {
324 .handler = sysrq_handle_term,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800325 .help_msg = "terminate-all-tasks(E)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326 .action_msg = "Terminate All Tasks",
327 .enable_mask = SYSRQ_ENABLE_SIGNAL,
328};
329
David Howells65f27f32006-11-22 14:55:48 +0000330static void moom_callback(struct work_struct *ignored)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331{
Mel Gorman0e884602008-04-28 02:12:14 -0700332 out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333}
334
David Howells65f27f32006-11-22 14:55:48 +0000335static DECLARE_WORK(moom_work, moom_callback);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336
David Howells7d12e782006-10-05 14:55:46 +0100337static void sysrq_handle_moom(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338{
339 schedule_work(&moom_work);
340}
341static struct sysrq_key_op sysrq_moom_op = {
342 .handler = sysrq_handle_moom,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800343 .help_msg = "memory-full-oom-kill(F)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 .action_msg = "Manual OOM execution",
Naohiro Ooiwab4236f82008-10-15 22:01:43 -0700345 .enable_mask = SYSRQ_ENABLE_SIGNAL,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346};
347
Eric Sandeenc2d75432009-03-31 15:23:46 -0700348#ifdef CONFIG_BLOCK
349static void sysrq_handle_thaw(int key, struct tty_struct *tty)
350{
351 emergency_thaw_all();
352}
353static struct sysrq_key_op sysrq_thaw_op = {
354 .handler = sysrq_handle_thaw,
355 .help_msg = "thaw-filesystems(J)",
356 .action_msg = "Emergency Thaw of all frozen filesystems",
357 .enable_mask = SYSRQ_ENABLE_SIGNAL,
358};
359#endif
360
David Howells7d12e782006-10-05 14:55:46 +0100361static void sysrq_handle_kill(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362{
363 send_sig_all(SIGKILL);
364 console_loglevel = 8;
365}
366static struct sysrq_key_op sysrq_kill_op = {
367 .handler = sysrq_handle_kill,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800368 .help_msg = "kill-all-tasks(I)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369 .action_msg = "Kill All Tasks",
370 .enable_mask = SYSRQ_ENABLE_SIGNAL,
371};
372
David Howells7d12e782006-10-05 14:55:46 +0100373static void sysrq_handle_unrt(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374{
375 normalize_rt_tasks();
376}
377static struct sysrq_key_op sysrq_unrt_op = {
378 .handler = sysrq_handle_unrt,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800379 .help_msg = "nice-all-RT-tasks(N)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380 .action_msg = "Nice All RT Tasks",
381 .enable_mask = SYSRQ_ENABLE_RTNICE,
382};
383
384/* Key Operations table and lock */
385static DEFINE_SPINLOCK(sysrq_key_table_lock);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800386
387static struct sysrq_key_op *sysrq_key_table[36] = {
388 &sysrq_loglevel_op, /* 0 */
389 &sysrq_loglevel_op, /* 1 */
390 &sysrq_loglevel_op, /* 2 */
391 &sysrq_loglevel_op, /* 3 */
392 &sysrq_loglevel_op, /* 4 */
393 &sysrq_loglevel_op, /* 5 */
394 &sysrq_loglevel_op, /* 6 */
395 &sysrq_loglevel_op, /* 7 */
396 &sysrq_loglevel_op, /* 8 */
397 &sysrq_loglevel_op, /* 9 */
398
399 /*
Randy Dunlapd346cce2007-01-31 23:48:17 -0800400 * a: Don't use for system provided sysrqs, it is handled specially on
401 * sparc and will never arrive.
Andrew Mortonbf36b902006-03-25 03:07:08 -0800402 */
403 NULL, /* a */
404 &sysrq_reboot_op, /* b */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800405 &sysrq_crashdump_op, /* c & ibm_emac driver debug */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800406 &sysrq_showlocks_op, /* d */
407 &sysrq_term_op, /* e */
408 &sysrq_moom_op, /* f */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800409 /* g: May be registered by ppc for kgdb */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800410 NULL, /* g */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700411 NULL, /* h - reserved for help */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800412 &sysrq_kill_op, /* i */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700413#ifdef CONFIG_BLOCK
414 &sysrq_thaw_op, /* j */
415#else
Andrew Mortonbf36b902006-03-25 03:07:08 -0800416 NULL, /* j */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700417#endif
Andrew Mortonbf36b902006-03-25 03:07:08 -0800418 &sysrq_SAK_op, /* k */
Rik van Riel5045bca2008-04-29 00:59:21 -0700419#ifdef CONFIG_SMP
420 &sysrq_showallcpus_op, /* l */
421#else
Andrew Mortonbf36b902006-03-25 03:07:08 -0800422 NULL, /* l */
Rik van Riel5045bca2008-04-29 00:59:21 -0700423#endif
Andrew Mortonbf36b902006-03-25 03:07:08 -0800424 &sysrq_showmem_op, /* m */
425 &sysrq_unrt_op, /* n */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800426 /* o: This will often be registered as 'Off' at init time */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800427 NULL, /* o */
428 &sysrq_showregs_op, /* p */
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800429 &sysrq_show_timers_op, /* q */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800430 &sysrq_unraw_op, /* r */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800431 &sysrq_sync_op, /* s */
432 &sysrq_showstate_op, /* t */
433 &sysrq_mountro_op, /* u */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800434 /* v: May be registered at init time by SMP VOYAGER */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800435 NULL, /* v */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800436 &sysrq_showstate_blocked_op, /* w */
437 /* x: May be registered on ppc/powerpc for xmon */
438 NULL, /* x */
David S. Miller93dae5b2008-05-19 23:46:00 -0700439 /* y: May be registered on sparc64 for global register dump */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800440 NULL, /* y */
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100441 &sysrq_ftrace_dump_op, /* z */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442};
443
444/* key2index calculation, -1 on invalid index */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800445static int sysrq_key_table_key2index(int key)
446{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700447 int retval;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800448
449 if ((key >= '0') && (key <= '9'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450 retval = key - '0';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800451 else if ((key >= 'a') && (key <= 'z'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 retval = key + 10 - 'a';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800453 else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700454 retval = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455 return retval;
456}
457
458/*
459 * get and put functions for the table, exposed to modules.
460 */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800461struct sysrq_key_op *__sysrq_get_key_op(int key)
462{
463 struct sysrq_key_op *op_p = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464 int i;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800465
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466 i = sysrq_key_table_key2index(key);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800467 if (i != -1)
468 op_p = sysrq_key_table[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469 return op_p;
470}
471
Andrew Mortonbf36b902006-03-25 03:07:08 -0800472static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
473{
474 int i = sysrq_key_table_key2index(key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476 if (i != -1)
477 sysrq_key_table[i] = op_p;
478}
479
480/*
Andrew Mortonbf36b902006-03-25 03:07:08 -0800481 * This is the non-locking version of handle_sysrq. It must/can only be called
482 * by sysrq key handlers, as they are inside of the lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483 */
David Howells7d12e782006-10-05 14:55:46 +0100484void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485{
486 struct sysrq_key_op *op_p;
487 int orig_log_level;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800488 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700489 unsigned long flags;
490
491 spin_lock_irqsave(&sysrq_key_table_lock, flags);
Andy Whitcroftfb144ad2009-01-15 13:50:52 -0800492 /*
493 * Raise the apparent loglevel to maximum so that the sysrq header
494 * is shown to provide the user with positive feedback. We do not
495 * simply emit this at KERN_EMERG as that would change message
496 * routing in the consumers of /proc/kmsg.
497 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498 orig_log_level = console_loglevel;
499 console_loglevel = 7;
500 printk(KERN_INFO "SysRq : ");
501
502 op_p = __sysrq_get_key_op(key);
503 if (op_p) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800504 /*
505 * Should we check for enabled operations (/proc/sysrq-trigger
506 * should not) and is the invoked operation enabled?
507 */
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800508 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800509 printk("%s\n", op_p->action_msg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510 console_loglevel = orig_log_level;
David Howells7d12e782006-10-05 14:55:46 +0100511 op_p->handler(key, tty);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800512 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513 printk("This sysrq operation is disabled.\n");
Andrew Mortonbf36b902006-03-25 03:07:08 -0800514 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515 } else {
516 printk("HELP : ");
517 /* Only print the help msg once per handler */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800518 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
519 if (sysrq_key_table[i]) {
520 int j;
521
522 for (j = 0; sysrq_key_table[i] !=
523 sysrq_key_table[j]; j++)
524 ;
525 if (j != i)
526 continue;
527 printk("%s ", sysrq_key_table[i]->help_msg);
528 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 }
Andrew Mortonbf36b902006-03-25 03:07:08 -0800530 printk("\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531 console_loglevel = orig_log_level;
532 }
533 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
534}
535
536/*
537 * This function is called by the keyboard handler when SysRq is pressed
538 * and any other keycode arrives.
539 */
David Howells7d12e782006-10-05 14:55:46 +0100540void handle_sysrq(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541{
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800542 if (sysrq_on())
543 __handle_sysrq(key, tty, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800545EXPORT_SYMBOL(handle_sysrq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546
Adrian Bunkcf62ddc2005-11-08 21:39:47 -0800547static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
Andrew Mortonbf36b902006-03-25 03:07:08 -0800548 struct sysrq_key_op *remove_op_p)
549{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550
551 int retval;
552 unsigned long flags;
553
554 spin_lock_irqsave(&sysrq_key_table_lock, flags);
555 if (__sysrq_get_key_op(key) == remove_op_p) {
556 __sysrq_put_key_op(key, insert_op_p);
557 retval = 0;
558 } else {
559 retval = -1;
560 }
561 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562 return retval;
563}
564
565int register_sysrq_key(int key, struct sysrq_key_op *op_p)
566{
567 return __sysrq_swap_key_ops(key, op_p, NULL);
568}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800569EXPORT_SYMBOL(register_sysrq_key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570
571int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
572{
573 return __sysrq_swap_key_ops(key, NULL, op_p);
574}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575EXPORT_SYMBOL(unregister_sysrq_key);
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700576
577#ifdef CONFIG_PROC_FS
578/*
579 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
580 */
581static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
582 size_t count, loff_t *ppos)
583{
584 if (count) {
585 char c;
586
587 if (get_user(c, buf))
588 return -EFAULT;
589 __handle_sysrq(c, NULL, 0);
590 }
591 return count;
592}
593
594static const struct file_operations proc_sysrq_trigger_operations = {
595 .write = write_sysrq_trigger,
596};
597
598static int __init sysrq_init(void)
599{
600 proc_create("sysrq-trigger", S_IWUSR, NULL, &proc_sysrq_trigger_operations);
601 return 0;
602}
603module_init(sysrq_init);
604#endif