blob: 44203ff599daa10420407265db91f88116473413 [file] [log] [blame]
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>
Ingo Molnarc1dc0b92009-08-02 11:28:21 +020027#include <linux/nmi.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070028#include <linux/quotaops.h>
Ingo Molnarcdd6c482009-09-21 12:02:48 +020029#include <linux/perf_event.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070030#include <linux/kernel.h>
31#include <linux/module.h>
32#include <linux/suspend.h>
33#include <linux/writeback.h>
34#include <linux/buffer_head.h> /* for fsync_bdev() */
35#include <linux/swap.h>
36#include <linux/spinlock.h>
37#include <linux/vt_kern.h>
38#include <linux/workqueue.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,
Randy Dunlap208b95c2009-01-06 14:41:13 -080085 .help_msg = "loglevel(0-9)",
Linus Torvalds1da177e2005-04-16 15:20:36 -070086 .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
Neil Hormand6580a92009-06-17 16:28:17 -0700124static void sysrq_handle_crash(int key, struct tty_struct *tty)
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700125{
Neil Hormand6580a92009-06-17 16:28:17 -0700126 char *killer = NULL;
Hidetoshi Setocab8bd32009-07-29 15:04:14 -0700127
128 panic_on_oops = 1; /* force panic */
129 wmb();
Neil Hormand6580a92009-06-17 16:28:17 -0700130 *killer = 1;
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700131}
Hidetoshi Setocab8bd32009-07-29 15:04:14 -0700132static struct sysrq_key_op sysrq_crash_op = {
Neil Hormand6580a92009-06-17 16:28:17 -0700133 .handler = sysrq_handle_crash,
134 .help_msg = "Crash",
135 .action_msg = "Trigger a crash",
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700136 .enable_mask = SYSRQ_ENABLE_DUMP,
137};
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700138
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{
Ingo Molnar47cab6a2009-08-03 09:31:54 +0200226 /*
227 * Fall back to the workqueue based printing if the
228 * backtrace printing did not succeed or the
229 * architecture has no support for it:
230 */
231 if (!trigger_all_cpu_backtrace()) {
232 struct pt_regs *regs = get_irq_regs();
233
234 if (regs) {
235 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
236 show_regs(regs);
237 }
238 schedule_work(&sysrq_showallcpus);
239 }
Rik van Riel5045bca2008-04-29 00:59:21 -0700240}
241
242static struct sysrq_key_op sysrq_showallcpus_op = {
243 .handler = sysrq_handle_showallcpus,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800244 .help_msg = "show-backtrace-all-active-cpus(L)",
Rik van Riel5045bca2008-04-29 00:59:21 -0700245 .action_msg = "Show backtrace of all active CPUs",
246 .enable_mask = SYSRQ_ENABLE_DUMP,
247};
248#endif
249
David Howells7d12e782006-10-05 14:55:46 +0100250static void sysrq_handle_showregs(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251{
David Howells7d12e782006-10-05 14:55:46 +0100252 struct pt_regs *regs = get_irq_regs();
253 if (regs)
254 show_regs(regs);
Ingo Molnarcdd6c482009-09-21 12:02:48 +0200255 perf_event_print_debug();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256}
257static struct sysrq_key_op sysrq_showregs_op = {
258 .handler = sysrq_handle_showregs,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800259 .help_msg = "show-registers(P)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260 .action_msg = "Show Regs",
261 .enable_mask = SYSRQ_ENABLE_DUMP,
262};
263
David Howells7d12e782006-10-05 14:55:46 +0100264static void sysrq_handle_showstate(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265{
266 show_state();
267}
268static struct sysrq_key_op sysrq_showstate_op = {
269 .handler = sysrq_handle_showstate,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800270 .help_msg = "show-task-states(T)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 .action_msg = "Show State",
272 .enable_mask = SYSRQ_ENABLE_DUMP,
273};
274
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800275static void sysrq_handle_showstate_blocked(int key, struct tty_struct *tty)
276{
277 show_state_filter(TASK_UNINTERRUPTIBLE);
278}
279static struct sysrq_key_op sysrq_showstate_blocked_op = {
280 .handler = sysrq_handle_showstate_blocked,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800281 .help_msg = "show-blocked-tasks(W)",
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800282 .action_msg = "Show Blocked State",
283 .enable_mask = SYSRQ_ENABLE_DUMP,
284};
285
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100286#ifdef CONFIG_TRACING
287#include <linux/ftrace.h>
288
289static void sysrq_ftrace_dump(int key, struct tty_struct *tty)
290{
291 ftrace_dump();
292}
293static struct sysrq_key_op sysrq_ftrace_dump_op = {
294 .handler = sysrq_ftrace_dump,
Randy Dunlap3871f2f2008-12-24 16:06:57 -0800295 .help_msg = "dump-ftrace-buffer(Z)",
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100296 .action_msg = "Dump ftrace buffer",
297 .enable_mask = SYSRQ_ENABLE_DUMP,
298};
299#else
300#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)0)
301#endif
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800302
David Howells7d12e782006-10-05 14:55:46 +0100303static void sysrq_handle_showmem(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304{
305 show_mem();
306}
307static struct sysrq_key_op sysrq_showmem_op = {
308 .handler = sysrq_handle_showmem,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800309 .help_msg = "show-memory-usage(M)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 .action_msg = "Show Memory",
311 .enable_mask = SYSRQ_ENABLE_DUMP,
312};
313
Andrew Mortonbf36b902006-03-25 03:07:08 -0800314/*
315 * Signal sysrq helper function. Sends a signal to all user processes.
316 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317static void send_sig_all(int sig)
318{
319 struct task_struct *p;
320
321 for_each_process(p) {
Serge E. Hallynb460cbc2007-10-18 23:39:52 -0700322 if (p->mm && !is_global_init(p))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 /* Not swapper, init nor kernel thread */
324 force_sig(sig, p);
325 }
326}
327
David Howells7d12e782006-10-05 14:55:46 +0100328static void sysrq_handle_term(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329{
330 send_sig_all(SIGTERM);
331 console_loglevel = 8;
332}
333static struct sysrq_key_op sysrq_term_op = {
334 .handler = sysrq_handle_term,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800335 .help_msg = "terminate-all-tasks(E)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 .action_msg = "Terminate All Tasks",
337 .enable_mask = SYSRQ_ENABLE_SIGNAL,
338};
339
David Howells65f27f32006-11-22 14:55:48 +0000340static void moom_callback(struct work_struct *ignored)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341{
Mel Gorman0e884602008-04-28 02:12:14 -0700342 out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343}
344
David Howells65f27f32006-11-22 14:55:48 +0000345static DECLARE_WORK(moom_work, moom_callback);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346
David Howells7d12e782006-10-05 14:55:46 +0100347static void sysrq_handle_moom(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348{
349 schedule_work(&moom_work);
350}
351static struct sysrq_key_op sysrq_moom_op = {
352 .handler = sysrq_handle_moom,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800353 .help_msg = "memory-full-oom-kill(F)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354 .action_msg = "Manual OOM execution",
Naohiro Ooiwab4236f82008-10-15 22:01:43 -0700355 .enable_mask = SYSRQ_ENABLE_SIGNAL,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356};
357
Eric Sandeenc2d75432009-03-31 15:23:46 -0700358#ifdef CONFIG_BLOCK
359static void sysrq_handle_thaw(int key, struct tty_struct *tty)
360{
361 emergency_thaw_all();
362}
363static struct sysrq_key_op sysrq_thaw_op = {
364 .handler = sysrq_handle_thaw,
365 .help_msg = "thaw-filesystems(J)",
366 .action_msg = "Emergency Thaw of all frozen filesystems",
367 .enable_mask = SYSRQ_ENABLE_SIGNAL,
368};
369#endif
370
David Howells7d12e782006-10-05 14:55:46 +0100371static void sysrq_handle_kill(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372{
373 send_sig_all(SIGKILL);
374 console_loglevel = 8;
375}
376static struct sysrq_key_op sysrq_kill_op = {
377 .handler = sysrq_handle_kill,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800378 .help_msg = "kill-all-tasks(I)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 .action_msg = "Kill All Tasks",
380 .enable_mask = SYSRQ_ENABLE_SIGNAL,
381};
382
David Howells7d12e782006-10-05 14:55:46 +0100383static void sysrq_handle_unrt(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384{
385 normalize_rt_tasks();
386}
387static struct sysrq_key_op sysrq_unrt_op = {
388 .handler = sysrq_handle_unrt,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800389 .help_msg = "nice-all-RT-tasks(N)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390 .action_msg = "Nice All RT Tasks",
391 .enable_mask = SYSRQ_ENABLE_RTNICE,
392};
393
394/* Key Operations table and lock */
395static DEFINE_SPINLOCK(sysrq_key_table_lock);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800396
397static struct sysrq_key_op *sysrq_key_table[36] = {
398 &sysrq_loglevel_op, /* 0 */
399 &sysrq_loglevel_op, /* 1 */
400 &sysrq_loglevel_op, /* 2 */
401 &sysrq_loglevel_op, /* 3 */
402 &sysrq_loglevel_op, /* 4 */
403 &sysrq_loglevel_op, /* 5 */
404 &sysrq_loglevel_op, /* 6 */
405 &sysrq_loglevel_op, /* 7 */
406 &sysrq_loglevel_op, /* 8 */
407 &sysrq_loglevel_op, /* 9 */
408
409 /*
Randy Dunlapd346cce2007-01-31 23:48:17 -0800410 * a: Don't use for system provided sysrqs, it is handled specially on
411 * sparc and will never arrive.
Andrew Mortonbf36b902006-03-25 03:07:08 -0800412 */
413 NULL, /* a */
414 &sysrq_reboot_op, /* b */
Hidetoshi Setocab8bd32009-07-29 15:04:14 -0700415 &sysrq_crash_op, /* c & ibm_emac driver debug */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800416 &sysrq_showlocks_op, /* d */
417 &sysrq_term_op, /* e */
418 &sysrq_moom_op, /* f */
Jason Wessel364b5b72009-05-13 21:56:59 -0500419 /* g: May be registered for the kernel debugger */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800420 NULL, /* g */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700421 NULL, /* h - reserved for help */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800422 &sysrq_kill_op, /* i */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700423#ifdef CONFIG_BLOCK
424 &sysrq_thaw_op, /* j */
425#else
Andrew Mortonbf36b902006-03-25 03:07:08 -0800426 NULL, /* j */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700427#endif
Andrew Mortonbf36b902006-03-25 03:07:08 -0800428 &sysrq_SAK_op, /* k */
Rik van Riel5045bca2008-04-29 00:59:21 -0700429#ifdef CONFIG_SMP
430 &sysrq_showallcpus_op, /* l */
431#else
Andrew Mortonbf36b902006-03-25 03:07:08 -0800432 NULL, /* l */
Rik van Riel5045bca2008-04-29 00:59:21 -0700433#endif
Andrew Mortonbf36b902006-03-25 03:07:08 -0800434 &sysrq_showmem_op, /* m */
435 &sysrq_unrt_op, /* n */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800436 /* o: This will often be registered as 'Off' at init time */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800437 NULL, /* o */
438 &sysrq_showregs_op, /* p */
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800439 &sysrq_show_timers_op, /* q */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800440 &sysrq_unraw_op, /* r */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800441 &sysrq_sync_op, /* s */
442 &sysrq_showstate_op, /* t */
443 &sysrq_mountro_op, /* u */
Jason Wessel364b5b72009-05-13 21:56:59 -0500444 /* v: May be registered for frame buffer console restore */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800445 NULL, /* v */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800446 &sysrq_showstate_blocked_op, /* w */
447 /* x: May be registered on ppc/powerpc for xmon */
448 NULL, /* x */
David S. Miller93dae5b2008-05-19 23:46:00 -0700449 /* y: May be registered on sparc64 for global register dump */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800450 NULL, /* y */
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100451 &sysrq_ftrace_dump_op, /* z */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452};
453
454/* key2index calculation, -1 on invalid index */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800455static int sysrq_key_table_key2index(int key)
456{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457 int retval;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800458
459 if ((key >= '0') && (key <= '9'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460 retval = key - '0';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800461 else if ((key >= 'a') && (key <= 'z'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462 retval = key + 10 - 'a';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800463 else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464 retval = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465 return retval;
466}
467
468/*
469 * get and put functions for the table, exposed to modules.
470 */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800471struct sysrq_key_op *__sysrq_get_key_op(int key)
472{
473 struct sysrq_key_op *op_p = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474 int i;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800475
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476 i = sysrq_key_table_key2index(key);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800477 if (i != -1)
478 op_p = sysrq_key_table[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479 return op_p;
480}
481
Andrew Mortonbf36b902006-03-25 03:07:08 -0800482static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
483{
484 int i = sysrq_key_table_key2index(key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486 if (i != -1)
487 sysrq_key_table[i] = op_p;
488}
489
490/*
Andrew Mortonbf36b902006-03-25 03:07:08 -0800491 * This is the non-locking version of handle_sysrq. It must/can only be called
492 * by sysrq key handlers, as they are inside of the lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493 */
David Howells7d12e782006-10-05 14:55:46 +0100494void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700495{
496 struct sysrq_key_op *op_p;
497 int orig_log_level;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800498 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700499 unsigned long flags;
500
501 spin_lock_irqsave(&sysrq_key_table_lock, flags);
Andy Whitcroftfb144ad2009-01-15 13:50:52 -0800502 /*
503 * Raise the apparent loglevel to maximum so that the sysrq header
504 * is shown to provide the user with positive feedback. We do not
505 * simply emit this at KERN_EMERG as that would change message
506 * routing in the consumers of /proc/kmsg.
507 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508 orig_log_level = console_loglevel;
509 console_loglevel = 7;
510 printk(KERN_INFO "SysRq : ");
511
512 op_p = __sysrq_get_key_op(key);
513 if (op_p) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800514 /*
515 * Should we check for enabled operations (/proc/sysrq-trigger
516 * should not) and is the invoked operation enabled?
517 */
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800518 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800519 printk("%s\n", op_p->action_msg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700520 console_loglevel = orig_log_level;
David Howells7d12e782006-10-05 14:55:46 +0100521 op_p->handler(key, tty);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800522 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523 printk("This sysrq operation is disabled.\n");
Andrew Mortonbf36b902006-03-25 03:07:08 -0800524 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525 } else {
526 printk("HELP : ");
527 /* Only print the help msg once per handler */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800528 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
529 if (sysrq_key_table[i]) {
530 int j;
531
532 for (j = 0; sysrq_key_table[i] !=
533 sysrq_key_table[j]; j++)
534 ;
535 if (j != i)
536 continue;
537 printk("%s ", sysrq_key_table[i]->help_msg);
538 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539 }
Andrew Mortonbf36b902006-03-25 03:07:08 -0800540 printk("\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541 console_loglevel = orig_log_level;
542 }
543 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
544}
545
546/*
547 * This function is called by the keyboard handler when SysRq is pressed
548 * and any other keycode arrives.
549 */
David Howells7d12e782006-10-05 14:55:46 +0100550void handle_sysrq(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551{
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800552 if (sysrq_on())
553 __handle_sysrq(key, tty, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800555EXPORT_SYMBOL(handle_sysrq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556
Adrian Bunkcf62ddc2005-11-08 21:39:47 -0800557static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
Andrew Mortonbf36b902006-03-25 03:07:08 -0800558 struct sysrq_key_op *remove_op_p)
559{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700560
561 int retval;
562 unsigned long flags;
563
564 spin_lock_irqsave(&sysrq_key_table_lock, flags);
565 if (__sysrq_get_key_op(key) == remove_op_p) {
566 __sysrq_put_key_op(key, insert_op_p);
567 retval = 0;
568 } else {
569 retval = -1;
570 }
571 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572 return retval;
573}
574
575int register_sysrq_key(int key, struct sysrq_key_op *op_p)
576{
577 return __sysrq_swap_key_ops(key, op_p, NULL);
578}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800579EXPORT_SYMBOL(register_sysrq_key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580
581int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
582{
583 return __sysrq_swap_key_ops(key, NULL, op_p);
584}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585EXPORT_SYMBOL(unregister_sysrq_key);
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700586
587#ifdef CONFIG_PROC_FS
588/*
589 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
590 */
591static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
592 size_t count, loff_t *ppos)
593{
594 if (count) {
595 char c;
596
597 if (get_user(c, buf))
598 return -EFAULT;
599 __handle_sysrq(c, NULL, 0);
600 }
601 return count;
602}
603
604static const struct file_operations proc_sysrq_trigger_operations = {
605 .write = write_sysrq_trigger,
606};
607
608static int __init sysrq_init(void)
609{
610 proc_create("sysrq-trigger", S_IWUSR, NULL, &proc_sysrq_trigger_operations);
611 return 0;
612}
613module_init(sysrq_init);
614#endif