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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>
David Howells7d12e782006-10-05 14:55:46 +010038#include <linux/irq.h>
Ingo Molnar88ad0bf62007-02-16 01:28:16 -080039#include <linux/hrtimer.h>
David Rientjes5a3135c22007-10-16 23:25:53 -070040#include <linux/oom.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070041
42#include <asm/ptrace.h>
Heiko Carstens2033b0c2006-10-06 16:38:42 +020043#include <asm/irq_regs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070044
45/* Whether we react on sysrq keys or just ignore them */
Ingo Molnar5d6f6472006-12-13 00:34:36 -080046int __read_mostly __sysrq_enabled = 1;
47
48static int __read_mostly sysrq_always_enabled;
49
50int sysrq_on(void)
51{
52 return __sysrq_enabled || sysrq_always_enabled;
53}
54
55/*
56 * A value of 1 means 'all', other nonzero values are an op mask:
57 */
58static inline int sysrq_on_mask(int mask)
59{
60 return sysrq_always_enabled || __sysrq_enabled == 1 ||
61 (__sysrq_enabled & mask);
62}
63
64static int __init sysrq_always_enabled_setup(char *str)
65{
66 sysrq_always_enabled = 1;
67 printk(KERN_INFO "debug: sysrq always enabled.\n");
68
69 return 1;
70}
71
72__setup("sysrq_always_enabled", sysrq_always_enabled_setup);
73
Linus Torvalds1da177e2005-04-16 15:20:36 -070074
David Howells7d12e782006-10-05 14:55:46 +010075static void sysrq_handle_loglevel(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -070076{
77 int i;
78 i = key - '0';
79 console_loglevel = 7;
80 printk("Loglevel set to %d\n", i);
81 console_loglevel = i;
Andrew Mortonbf36b902006-03-25 03:07:08 -080082}
Linus Torvalds1da177e2005-04-16 15:20:36 -070083static struct sysrq_key_op sysrq_loglevel_op = {
84 .handler = sysrq_handle_loglevel,
85 .help_msg = "loglevel0-8",
86 .action_msg = "Changing Loglevel",
87 .enable_mask = SYSRQ_ENABLE_LOG,
88};
89
Linus Torvalds1da177e2005-04-16 15:20:36 -070090#ifdef CONFIG_VT
David Howells7d12e782006-10-05 14:55:46 +010091static void sysrq_handle_SAK(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -070092{
Eric W. Biederman8b6312f2007-02-10 01:44:34 -080093 struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
Eric W. Biederman8b6312f2007-02-10 01:44:34 -080094 schedule_work(SAK_work);
Linus Torvalds1da177e2005-04-16 15:20:36 -070095}
96static struct sysrq_key_op sysrq_SAK_op = {
97 .handler = sysrq_handle_SAK,
98 .help_msg = "saK",
99 .action_msg = "SAK",
100 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
101};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800102#else
103#define sysrq_SAK_op (*(struct sysrq_key_op *)0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104#endif
105
106#ifdef CONFIG_VT
David Howells7d12e782006-10-05 14:55:46 +0100107static void sysrq_handle_unraw(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108{
109 struct kbd_struct *kbd = &kbd_table[fg_console];
110
111 if (kbd)
Bill Nottingham2e8ecb92007-10-16 23:29:38 -0700112 kbd->kbdmode = default_utf8 ? VC_UNICODE : VC_XLATE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113}
114static struct sysrq_key_op sysrq_unraw_op = {
115 .handler = sysrq_handle_unraw,
116 .help_msg = "unRaw",
Bill Nottingham2e8ecb92007-10-16 23:29:38 -0700117 .action_msg = "Keyboard mode set to system default",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
119};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800120#else
121#define sysrq_unraw_op (*(struct sysrq_key_op *)0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122#endif /* CONFIG_VT */
123
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700124#ifdef CONFIG_KEXEC
David Howells7d12e782006-10-05 14:55:46 +0100125static void sysrq_handle_crashdump(int key, struct tty_struct *tty)
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700126{
David Howells7d12e782006-10-05 14:55:46 +0100127 crash_kexec(get_irq_regs());
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700128}
129static struct sysrq_key_op sysrq_crashdump_op = {
130 .handler = sysrq_handle_crashdump,
131 .help_msg = "Crashdump",
132 .action_msg = "Trigger a crashdump",
133 .enable_mask = SYSRQ_ENABLE_DUMP,
134};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800135#else
136#define sysrq_crashdump_op (*(struct sysrq_key_op *)0)
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700137#endif
138
David Howells7d12e782006-10-05 14:55:46 +0100139static void sysrq_handle_reboot(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140{
Peter Zijlstrab2e9c7d2006-09-30 23:28:02 -0700141 lockdep_off();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 local_irq_enable();
Eric W. Biederman4de8b9b2005-07-26 11:51:06 -0600143 emergency_restart();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145static struct sysrq_key_op sysrq_reboot_op = {
146 .handler = sysrq_handle_reboot,
147 .help_msg = "reBoot",
148 .action_msg = "Resetting",
149 .enable_mask = SYSRQ_ENABLE_BOOT,
150};
151
David Howells7d12e782006-10-05 14:55:46 +0100152static void sysrq_handle_sync(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153{
154 emergency_sync();
155}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156static struct sysrq_key_op sysrq_sync_op = {
157 .handler = sysrq_handle_sync,
158 .help_msg = "Sync",
159 .action_msg = "Emergency Sync",
160 .enable_mask = SYSRQ_ENABLE_SYNC,
161};
162
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800163static void sysrq_handle_show_timers(int key, struct tty_struct *tty)
164{
165 sysrq_timer_list_show();
166}
167
168static struct sysrq_key_op sysrq_show_timers_op = {
169 .handler = sysrq_handle_show_timers,
170 .help_msg = "show-all-timers(Q)",
Thomas Gleixner322acf62008-10-20 12:33:14 +0200171 .action_msg = "Show clockevent devices & pending hrtimers (no others)",
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800172};
173
David Howells7d12e782006-10-05 14:55:46 +0100174static void sysrq_handle_mountro(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175{
176 emergency_remount();
177}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178static struct sysrq_key_op sysrq_mountro_op = {
179 .handler = sysrq_handle_mountro,
180 .help_msg = "Unmount",
181 .action_msg = "Emergency Remount R/O",
182 .enable_mask = SYSRQ_ENABLE_REMOUNT,
183};
184
Ingo Molnar8c645802006-07-03 00:24:56 -0700185#ifdef CONFIG_LOCKDEP
David Howells7d12e782006-10-05 14:55:46 +0100186static void sysrq_handle_showlocks(int key, struct tty_struct *tty)
Ingo Molnarde5097c2006-01-09 15:59:21 -0800187{
Ingo Molnar9a11b49a2006-07-03 00:24:33 -0700188 debug_show_all_locks();
Ingo Molnarde5097c2006-01-09 15:59:21 -0800189}
Ingo Molnar8c645802006-07-03 00:24:56 -0700190
Ingo Molnarde5097c2006-01-09 15:59:21 -0800191static struct sysrq_key_op sysrq_showlocks_op = {
192 .handler = sysrq_handle_showlocks,
193 .help_msg = "show-all-locks(D)",
194 .action_msg = "Show Locks Held",
195};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800196#else
197#define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
Ingo Molnarde5097c2006-01-09 15:59:21 -0800198#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199
Rik van Riel5045bca2008-04-29 00:59:21 -0700200#ifdef CONFIG_SMP
201static DEFINE_SPINLOCK(show_lock);
202
203static void showacpu(void *dummy)
204{
205 unsigned long flags;
206
207 /* Idle CPUs have no interesting backtrace. */
208 if (idle_cpu(smp_processor_id()))
209 return;
210
211 spin_lock_irqsave(&show_lock, flags);
212 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
213 show_stack(NULL, NULL);
214 spin_unlock_irqrestore(&show_lock, flags);
215}
216
217static void sysrq_showregs_othercpus(struct work_struct *dummy)
218{
Ingo Molnar8b604d52008-06-27 11:52:45 +0200219 smp_call_function(showacpu, NULL, 0);
Rik van Riel5045bca2008-04-29 00:59:21 -0700220}
221
222static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
223
224static void sysrq_handle_showallcpus(int key, struct tty_struct *tty)
225{
226 struct pt_regs *regs = get_irq_regs();
227 if (regs) {
228 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
229 show_regs(regs);
230 }
231 schedule_work(&sysrq_showallcpus);
232}
233
234static struct sysrq_key_op sysrq_showallcpus_op = {
235 .handler = sysrq_handle_showallcpus,
236 .help_msg = "aLlcpus",
237 .action_msg = "Show backtrace of all active CPUs",
238 .enable_mask = SYSRQ_ENABLE_DUMP,
239};
240#endif
241
David Howells7d12e782006-10-05 14:55:46 +0100242static void sysrq_handle_showregs(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243{
David Howells7d12e782006-10-05 14:55:46 +0100244 struct pt_regs *regs = get_irq_regs();
245 if (regs)
246 show_regs(regs);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247}
248static struct sysrq_key_op sysrq_showregs_op = {
249 .handler = sysrq_handle_showregs,
250 .help_msg = "showPc",
251 .action_msg = "Show Regs",
252 .enable_mask = SYSRQ_ENABLE_DUMP,
253};
254
David Howells7d12e782006-10-05 14:55:46 +0100255static void sysrq_handle_showstate(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256{
257 show_state();
258}
259static struct sysrq_key_op sysrq_showstate_op = {
260 .handler = sysrq_handle_showstate,
261 .help_msg = "showTasks",
262 .action_msg = "Show State",
263 .enable_mask = SYSRQ_ENABLE_DUMP,
264};
265
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800266static void sysrq_handle_showstate_blocked(int key, struct tty_struct *tty)
267{
268 show_state_filter(TASK_UNINTERRUPTIBLE);
269}
270static struct sysrq_key_op sysrq_showstate_blocked_op = {
271 .handler = sysrq_handle_showstate_blocked,
Randy Dunlapd346cce2007-01-31 23:48:17 -0800272 .help_msg = "shoW-blocked-tasks",
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800273 .action_msg = "Show Blocked State",
274 .enable_mask = SYSRQ_ENABLE_DUMP,
275};
276
277
David Howells7d12e782006-10-05 14:55:46 +0100278static void sysrq_handle_showmem(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279{
280 show_mem();
281}
282static struct sysrq_key_op sysrq_showmem_op = {
283 .handler = sysrq_handle_showmem,
284 .help_msg = "showMem",
285 .action_msg = "Show Memory",
286 .enable_mask = SYSRQ_ENABLE_DUMP,
287};
288
Andrew Mortonbf36b902006-03-25 03:07:08 -0800289/*
290 * Signal sysrq helper function. Sends a signal to all user processes.
291 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292static void send_sig_all(int sig)
293{
294 struct task_struct *p;
295
296 for_each_process(p) {
Serge E. Hallynb460cbc2007-10-18 23:39:52 -0700297 if (p->mm && !is_global_init(p))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298 /* Not swapper, init nor kernel thread */
299 force_sig(sig, p);
300 }
301}
302
David Howells7d12e782006-10-05 14:55:46 +0100303static void sysrq_handle_term(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304{
305 send_sig_all(SIGTERM);
306 console_loglevel = 8;
307}
308static struct sysrq_key_op sysrq_term_op = {
309 .handler = sysrq_handle_term,
310 .help_msg = "tErm",
311 .action_msg = "Terminate All Tasks",
312 .enable_mask = SYSRQ_ENABLE_SIGNAL,
313};
314
David Howells65f27f32006-11-22 14:55:48 +0000315static void moom_callback(struct work_struct *ignored)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316{
Mel Gorman0e884602008-04-28 02:12:14 -0700317 out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318}
319
David Howells65f27f32006-11-22 14:55:48 +0000320static DECLARE_WORK(moom_work, moom_callback);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321
David Howells7d12e782006-10-05 14:55:46 +0100322static void sysrq_handle_moom(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323{
324 schedule_work(&moom_work);
325}
326static struct sysrq_key_op sysrq_moom_op = {
327 .handler = sysrq_handle_moom,
328 .help_msg = "Full",
329 .action_msg = "Manual OOM execution",
Naohiro Ooiwab4236f82008-10-15 22:01:43 -0700330 .enable_mask = SYSRQ_ENABLE_SIGNAL,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331};
332
David Howells7d12e782006-10-05 14:55:46 +0100333static void sysrq_handle_kill(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334{
335 send_sig_all(SIGKILL);
336 console_loglevel = 8;
337}
338static struct sysrq_key_op sysrq_kill_op = {
339 .handler = sysrq_handle_kill,
340 .help_msg = "kIll",
341 .action_msg = "Kill All Tasks",
342 .enable_mask = SYSRQ_ENABLE_SIGNAL,
343};
344
David Howells7d12e782006-10-05 14:55:46 +0100345static void sysrq_handle_unrt(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346{
347 normalize_rt_tasks();
348}
349static struct sysrq_key_op sysrq_unrt_op = {
350 .handler = sysrq_handle_unrt,
351 .help_msg = "Nice",
352 .action_msg = "Nice All RT Tasks",
353 .enable_mask = SYSRQ_ENABLE_RTNICE,
354};
355
356/* Key Operations table and lock */
357static DEFINE_SPINLOCK(sysrq_key_table_lock);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800358
359static struct sysrq_key_op *sysrq_key_table[36] = {
360 &sysrq_loglevel_op, /* 0 */
361 &sysrq_loglevel_op, /* 1 */
362 &sysrq_loglevel_op, /* 2 */
363 &sysrq_loglevel_op, /* 3 */
364 &sysrq_loglevel_op, /* 4 */
365 &sysrq_loglevel_op, /* 5 */
366 &sysrq_loglevel_op, /* 6 */
367 &sysrq_loglevel_op, /* 7 */
368 &sysrq_loglevel_op, /* 8 */
369 &sysrq_loglevel_op, /* 9 */
370
371 /*
Randy Dunlapd346cce2007-01-31 23:48:17 -0800372 * a: Don't use for system provided sysrqs, it is handled specially on
373 * sparc and will never arrive.
Andrew Mortonbf36b902006-03-25 03:07:08 -0800374 */
375 NULL, /* a */
376 &sysrq_reboot_op, /* b */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800377 &sysrq_crashdump_op, /* c & ibm_emac driver debug */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800378 &sysrq_showlocks_op, /* d */
379 &sysrq_term_op, /* e */
380 &sysrq_moom_op, /* f */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800381 /* g: May be registered by ppc for kgdb */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800382 NULL, /* g */
383 NULL, /* h */
384 &sysrq_kill_op, /* i */
385 NULL, /* j */
386 &sysrq_SAK_op, /* k */
Rik van Riel5045bca2008-04-29 00:59:21 -0700387#ifdef CONFIG_SMP
388 &sysrq_showallcpus_op, /* l */
389#else
Andrew Mortonbf36b902006-03-25 03:07:08 -0800390 NULL, /* l */
Rik van Riel5045bca2008-04-29 00:59:21 -0700391#endif
Andrew Mortonbf36b902006-03-25 03:07:08 -0800392 &sysrq_showmem_op, /* m */
393 &sysrq_unrt_op, /* n */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800394 /* o: This will often be registered as 'Off' at init time */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800395 NULL, /* o */
396 &sysrq_showregs_op, /* p */
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800397 &sysrq_show_timers_op, /* q */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800398 &sysrq_unraw_op, /* r */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800399 &sysrq_sync_op, /* s */
400 &sysrq_showstate_op, /* t */
401 &sysrq_mountro_op, /* u */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800402 /* v: May be registered at init time by SMP VOYAGER */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800403 NULL, /* v */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800404 &sysrq_showstate_blocked_op, /* w */
405 /* x: May be registered on ppc/powerpc for xmon */
406 NULL, /* x */
David S. Miller93dae5b2008-05-19 23:46:00 -0700407 /* y: May be registered on sparc64 for global register dump */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800408 NULL, /* y */
409 NULL /* z */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410};
411
412/* key2index calculation, -1 on invalid index */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800413static int sysrq_key_table_key2index(int key)
414{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 int retval;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800416
417 if ((key >= '0') && (key <= '9'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 retval = key - '0';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800419 else if ((key >= 'a') && (key <= 'z'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420 retval = key + 10 - 'a';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800421 else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422 retval = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423 return retval;
424}
425
426/*
427 * get and put functions for the table, exposed to modules.
428 */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800429struct sysrq_key_op *__sysrq_get_key_op(int key)
430{
431 struct sysrq_key_op *op_p = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 int i;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800433
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434 i = sysrq_key_table_key2index(key);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800435 if (i != -1)
436 op_p = sysrq_key_table[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700437 return op_p;
438}
439
Andrew Mortonbf36b902006-03-25 03:07:08 -0800440static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
441{
442 int i = sysrq_key_table_key2index(key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443
Linus Torvalds1da177e2005-04-16 15:20:36 -0700444 if (i != -1)
445 sysrq_key_table[i] = op_p;
446}
447
448/*
Andrew Mortonbf36b902006-03-25 03:07:08 -0800449 * This is the non-locking version of handle_sysrq. It must/can only be called
450 * by sysrq key handlers, as they are inside of the lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700451 */
David Howells7d12e782006-10-05 14:55:46 +0100452void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700453{
454 struct sysrq_key_op *op_p;
455 int orig_log_level;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800456 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457 unsigned long flags;
458
459 spin_lock_irqsave(&sysrq_key_table_lock, flags);
460 orig_log_level = console_loglevel;
461 console_loglevel = 7;
462 printk(KERN_INFO "SysRq : ");
463
464 op_p = __sysrq_get_key_op(key);
465 if (op_p) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800466 /*
467 * Should we check for enabled operations (/proc/sysrq-trigger
468 * should not) and is the invoked operation enabled?
469 */
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800470 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800471 printk("%s\n", op_p->action_msg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472 console_loglevel = orig_log_level;
David Howells7d12e782006-10-05 14:55:46 +0100473 op_p->handler(key, tty);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800474 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475 printk("This sysrq operation is disabled.\n");
Andrew Mortonbf36b902006-03-25 03:07:08 -0800476 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477 } else {
478 printk("HELP : ");
479 /* Only print the help msg once per handler */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800480 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
481 if (sysrq_key_table[i]) {
482 int j;
483
484 for (j = 0; sysrq_key_table[i] !=
485 sysrq_key_table[j]; j++)
486 ;
487 if (j != i)
488 continue;
489 printk("%s ", sysrq_key_table[i]->help_msg);
490 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491 }
Andrew Mortonbf36b902006-03-25 03:07:08 -0800492 printk("\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493 console_loglevel = orig_log_level;
494 }
495 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
496}
497
498/*
499 * This function is called by the keyboard handler when SysRq is pressed
500 * and any other keycode arrives.
501 */
David Howells7d12e782006-10-05 14:55:46 +0100502void handle_sysrq(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503{
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800504 if (sysrq_on())
505 __handle_sysrq(key, tty, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800507EXPORT_SYMBOL(handle_sysrq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508
Adrian Bunkcf62ddc2005-11-08 21:39:47 -0800509static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
Andrew Mortonbf36b902006-03-25 03:07:08 -0800510 struct sysrq_key_op *remove_op_p)
511{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512
513 int retval;
514 unsigned long flags;
515
516 spin_lock_irqsave(&sysrq_key_table_lock, flags);
517 if (__sysrq_get_key_op(key) == remove_op_p) {
518 __sysrq_put_key_op(key, insert_op_p);
519 retval = 0;
520 } else {
521 retval = -1;
522 }
523 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524 return retval;
525}
526
527int register_sysrq_key(int key, struct sysrq_key_op *op_p)
528{
529 return __sysrq_swap_key_ops(key, op_p, NULL);
530}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800531EXPORT_SYMBOL(register_sysrq_key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532
533int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
534{
535 return __sysrq_swap_key_ops(key, NULL, op_p);
536}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537EXPORT_SYMBOL(unregister_sysrq_key);
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700538
539#ifdef CONFIG_PROC_FS
540/*
541 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
542 */
543static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
544 size_t count, loff_t *ppos)
545{
546 if (count) {
547 char c;
548
549 if (get_user(c, buf))
550 return -EFAULT;
551 __handle_sysrq(c, NULL, 0);
552 }
553 return count;
554}
555
556static const struct file_operations proc_sysrq_trigger_operations = {
557 .write = write_sysrq_trigger,
558};
559
560static int __init sysrq_init(void)
561{
562 proc_create("sysrq-trigger", S_IWUSR, NULL, &proc_sysrq_trigger_operations);
563 return 0;
564}
565module_init(sysrq_init);
566#endif