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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>
Thomas Gleixner0793a612008-12-04 20:12:29 +010028#include <linux/perf_counter.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#include <linux/kernel.h>
30#include <linux/module.h>
31#include <linux/suspend.h>
32#include <linux/writeback.h>
33#include <linux/buffer_head.h> /* for fsync_bdev() */
34#include <linux/swap.h>
35#include <linux/spinlock.h>
36#include <linux/vt_kern.h>
37#include <linux/workqueue.h>
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -070038#include <linux/kexec.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
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,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800236 .help_msg = "show-backtrace-all-active-cpus(L)",
Rik van Riel5045bca2008-04-29 00:59:21 -0700237 .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);
Thomas Gleixner0793a612008-12-04 20:12:29 +0100247 perf_counter_print_debug();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248}
249static struct sysrq_key_op sysrq_showregs_op = {
250 .handler = sysrq_handle_showregs,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800251 .help_msg = "show-registers(P)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252 .action_msg = "Show Regs",
253 .enable_mask = SYSRQ_ENABLE_DUMP,
254};
255
David Howells7d12e782006-10-05 14:55:46 +0100256static void sysrq_handle_showstate(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257{
258 show_state();
259}
260static struct sysrq_key_op sysrq_showstate_op = {
261 .handler = sysrq_handle_showstate,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800262 .help_msg = "show-task-states(T)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263 .action_msg = "Show State",
264 .enable_mask = SYSRQ_ENABLE_DUMP,
265};
266
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800267static void sysrq_handle_showstate_blocked(int key, struct tty_struct *tty)
268{
269 show_state_filter(TASK_UNINTERRUPTIBLE);
270}
271static struct sysrq_key_op sysrq_showstate_blocked_op = {
272 .handler = sysrq_handle_showstate_blocked,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800273 .help_msg = "show-blocked-tasks(W)",
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800274 .action_msg = "Show Blocked State",
275 .enable_mask = SYSRQ_ENABLE_DUMP,
276};
277
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100278#ifdef CONFIG_TRACING
279#include <linux/ftrace.h>
280
281static void sysrq_ftrace_dump(int key, struct tty_struct *tty)
282{
283 ftrace_dump();
284}
285static struct sysrq_key_op sysrq_ftrace_dump_op = {
286 .handler = sysrq_ftrace_dump,
Randy Dunlap3871f2f2008-12-24 16:06:57 -0800287 .help_msg = "dump-ftrace-buffer(Z)",
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100288 .action_msg = "Dump ftrace buffer",
289 .enable_mask = SYSRQ_ENABLE_DUMP,
290};
291#else
292#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)0)
293#endif
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800294
David Howells7d12e782006-10-05 14:55:46 +0100295static void sysrq_handle_showmem(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296{
297 show_mem();
298}
299static struct sysrq_key_op sysrq_showmem_op = {
300 .handler = sysrq_handle_showmem,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800301 .help_msg = "show-memory-usage(M)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302 .action_msg = "Show Memory",
303 .enable_mask = SYSRQ_ENABLE_DUMP,
304};
305
Andrew Mortonbf36b902006-03-25 03:07:08 -0800306/*
307 * Signal sysrq helper function. Sends a signal to all user processes.
308 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309static void send_sig_all(int sig)
310{
311 struct task_struct *p;
312
313 for_each_process(p) {
Serge E. Hallynb460cbc2007-10-18 23:39:52 -0700314 if (p->mm && !is_global_init(p))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315 /* Not swapper, init nor kernel thread */
316 force_sig(sig, p);
317 }
318}
319
David Howells7d12e782006-10-05 14:55:46 +0100320static void sysrq_handle_term(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321{
322 send_sig_all(SIGTERM);
323 console_loglevel = 8;
324}
325static struct sysrq_key_op sysrq_term_op = {
326 .handler = sysrq_handle_term,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800327 .help_msg = "terminate-all-tasks(E)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328 .action_msg = "Terminate All Tasks",
329 .enable_mask = SYSRQ_ENABLE_SIGNAL,
330};
331
David Howells65f27f32006-11-22 14:55:48 +0000332static void moom_callback(struct work_struct *ignored)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333{
Mel Gorman0e884602008-04-28 02:12:14 -0700334 out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335}
336
David Howells65f27f32006-11-22 14:55:48 +0000337static DECLARE_WORK(moom_work, moom_callback);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338
David Howells7d12e782006-10-05 14:55:46 +0100339static void sysrq_handle_moom(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340{
341 schedule_work(&moom_work);
342}
343static struct sysrq_key_op sysrq_moom_op = {
344 .handler = sysrq_handle_moom,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800345 .help_msg = "memory-full-oom-kill(F)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346 .action_msg = "Manual OOM execution",
Naohiro Ooiwab4236f82008-10-15 22:01:43 -0700347 .enable_mask = SYSRQ_ENABLE_SIGNAL,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348};
349
Eric Sandeenc2d75432009-03-31 15:23:46 -0700350#ifdef CONFIG_BLOCK
351static void sysrq_handle_thaw(int key, struct tty_struct *tty)
352{
353 emergency_thaw_all();
354}
355static struct sysrq_key_op sysrq_thaw_op = {
356 .handler = sysrq_handle_thaw,
357 .help_msg = "thaw-filesystems(J)",
358 .action_msg = "Emergency Thaw of all frozen filesystems",
359 .enable_mask = SYSRQ_ENABLE_SIGNAL,
360};
361#endif
362
David Howells7d12e782006-10-05 14:55:46 +0100363static void sysrq_handle_kill(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364{
365 send_sig_all(SIGKILL);
366 console_loglevel = 8;
367}
368static struct sysrq_key_op sysrq_kill_op = {
369 .handler = sysrq_handle_kill,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800370 .help_msg = "kill-all-tasks(I)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371 .action_msg = "Kill All Tasks",
372 .enable_mask = SYSRQ_ENABLE_SIGNAL,
373};
374
David Howells7d12e782006-10-05 14:55:46 +0100375static void sysrq_handle_unrt(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376{
377 normalize_rt_tasks();
378}
379static struct sysrq_key_op sysrq_unrt_op = {
380 .handler = sysrq_handle_unrt,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800381 .help_msg = "nice-all-RT-tasks(N)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 .action_msg = "Nice All RT Tasks",
383 .enable_mask = SYSRQ_ENABLE_RTNICE,
384};
385
386/* Key Operations table and lock */
387static DEFINE_SPINLOCK(sysrq_key_table_lock);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800388
389static struct sysrq_key_op *sysrq_key_table[36] = {
390 &sysrq_loglevel_op, /* 0 */
391 &sysrq_loglevel_op, /* 1 */
392 &sysrq_loglevel_op, /* 2 */
393 &sysrq_loglevel_op, /* 3 */
394 &sysrq_loglevel_op, /* 4 */
395 &sysrq_loglevel_op, /* 5 */
396 &sysrq_loglevel_op, /* 6 */
397 &sysrq_loglevel_op, /* 7 */
398 &sysrq_loglevel_op, /* 8 */
399 &sysrq_loglevel_op, /* 9 */
400
401 /*
Randy Dunlapd346cce2007-01-31 23:48:17 -0800402 * a: Don't use for system provided sysrqs, it is handled specially on
403 * sparc and will never arrive.
Andrew Mortonbf36b902006-03-25 03:07:08 -0800404 */
405 NULL, /* a */
406 &sysrq_reboot_op, /* b */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800407 &sysrq_crashdump_op, /* c & ibm_emac driver debug */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800408 &sysrq_showlocks_op, /* d */
409 &sysrq_term_op, /* e */
410 &sysrq_moom_op, /* f */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800411 /* g: May be registered by ppc for kgdb */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800412 NULL, /* g */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700413 NULL, /* h - reserved for help */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800414 &sysrq_kill_op, /* i */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700415#ifdef CONFIG_BLOCK
416 &sysrq_thaw_op, /* j */
417#else
Andrew Mortonbf36b902006-03-25 03:07:08 -0800418 NULL, /* j */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700419#endif
Andrew Mortonbf36b902006-03-25 03:07:08 -0800420 &sysrq_SAK_op, /* k */
Rik van Riel5045bca2008-04-29 00:59:21 -0700421#ifdef CONFIG_SMP
422 &sysrq_showallcpus_op, /* l */
423#else
Andrew Mortonbf36b902006-03-25 03:07:08 -0800424 NULL, /* l */
Rik van Riel5045bca2008-04-29 00:59:21 -0700425#endif
Andrew Mortonbf36b902006-03-25 03:07:08 -0800426 &sysrq_showmem_op, /* m */
427 &sysrq_unrt_op, /* n */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800428 /* o: This will often be registered as 'Off' at init time */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800429 NULL, /* o */
430 &sysrq_showregs_op, /* p */
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800431 &sysrq_show_timers_op, /* q */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800432 &sysrq_unraw_op, /* r */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800433 &sysrq_sync_op, /* s */
434 &sysrq_showstate_op, /* t */
435 &sysrq_mountro_op, /* u */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800436 /* v: May be registered at init time by SMP VOYAGER */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800437 NULL, /* v */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800438 &sysrq_showstate_blocked_op, /* w */
439 /* x: May be registered on ppc/powerpc for xmon */
440 NULL, /* x */
David S. Miller93dae5b2008-05-19 23:46:00 -0700441 /* y: May be registered on sparc64 for global register dump */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800442 NULL, /* y */
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100443 &sysrq_ftrace_dump_op, /* z */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700444};
445
446/* key2index calculation, -1 on invalid index */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800447static int sysrq_key_table_key2index(int key)
448{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700449 int retval;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800450
451 if ((key >= '0') && (key <= '9'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 retval = key - '0';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800453 else if ((key >= 'a') && (key <= 'z'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700454 retval = key + 10 - 'a';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800455 else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456 retval = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457 return retval;
458}
459
460/*
461 * get and put functions for the table, exposed to modules.
462 */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800463struct sysrq_key_op *__sysrq_get_key_op(int key)
464{
465 struct sysrq_key_op *op_p = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466 int i;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800467
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468 i = sysrq_key_table_key2index(key);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800469 if (i != -1)
470 op_p = sysrq_key_table[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 return op_p;
472}
473
Andrew Mortonbf36b902006-03-25 03:07:08 -0800474static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
475{
476 int i = sysrq_key_table_key2index(key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477
Linus Torvalds1da177e2005-04-16 15:20:36 -0700478 if (i != -1)
479 sysrq_key_table[i] = op_p;
480}
481
482/*
Andrew Mortonbf36b902006-03-25 03:07:08 -0800483 * This is the non-locking version of handle_sysrq. It must/can only be called
484 * by sysrq key handlers, as they are inside of the lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485 */
David Howells7d12e782006-10-05 14:55:46 +0100486void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487{
488 struct sysrq_key_op *op_p;
489 int orig_log_level;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800490 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491 unsigned long flags;
492
493 spin_lock_irqsave(&sysrq_key_table_lock, flags);
Andy Whitcroftfb144ad2009-01-15 13:50:52 -0800494 /*
495 * Raise the apparent loglevel to maximum so that the sysrq header
496 * is shown to provide the user with positive feedback. We do not
497 * simply emit this at KERN_EMERG as that would change message
498 * routing in the consumers of /proc/kmsg.
499 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500 orig_log_level = console_loglevel;
501 console_loglevel = 7;
502 printk(KERN_INFO "SysRq : ");
503
504 op_p = __sysrq_get_key_op(key);
505 if (op_p) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800506 /*
507 * Should we check for enabled operations (/proc/sysrq-trigger
508 * should not) and is the invoked operation enabled?
509 */
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800510 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800511 printk("%s\n", op_p->action_msg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512 console_loglevel = orig_log_level;
David Howells7d12e782006-10-05 14:55:46 +0100513 op_p->handler(key, tty);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800514 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515 printk("This sysrq operation is disabled.\n");
Andrew Mortonbf36b902006-03-25 03:07:08 -0800516 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700517 } else {
518 printk("HELP : ");
519 /* Only print the help msg once per handler */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800520 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
521 if (sysrq_key_table[i]) {
522 int j;
523
524 for (j = 0; sysrq_key_table[i] !=
525 sysrq_key_table[j]; j++)
526 ;
527 if (j != i)
528 continue;
529 printk("%s ", sysrq_key_table[i]->help_msg);
530 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531 }
Andrew Mortonbf36b902006-03-25 03:07:08 -0800532 printk("\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533 console_loglevel = orig_log_level;
534 }
535 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
536}
537
538/*
539 * This function is called by the keyboard handler when SysRq is pressed
540 * and any other keycode arrives.
541 */
David Howells7d12e782006-10-05 14:55:46 +0100542void handle_sysrq(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543{
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800544 if (sysrq_on())
545 __handle_sysrq(key, tty, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800547EXPORT_SYMBOL(handle_sysrq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548
Adrian Bunkcf62ddc2005-11-08 21:39:47 -0800549static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
Andrew Mortonbf36b902006-03-25 03:07:08 -0800550 struct sysrq_key_op *remove_op_p)
551{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552
553 int retval;
554 unsigned long flags;
555
556 spin_lock_irqsave(&sysrq_key_table_lock, flags);
557 if (__sysrq_get_key_op(key) == remove_op_p) {
558 __sysrq_put_key_op(key, insert_op_p);
559 retval = 0;
560 } else {
561 retval = -1;
562 }
563 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700564 return retval;
565}
566
567int register_sysrq_key(int key, struct sysrq_key_op *op_p)
568{
569 return __sysrq_swap_key_ops(key, op_p, NULL);
570}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800571EXPORT_SYMBOL(register_sysrq_key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572
573int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
574{
575 return __sysrq_swap_key_ops(key, NULL, op_p);
576}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700577EXPORT_SYMBOL(unregister_sysrq_key);
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700578
579#ifdef CONFIG_PROC_FS
580/*
581 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
582 */
583static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
584 size_t count, loff_t *ppos)
585{
586 if (count) {
587 char c;
588
589 if (get_user(c, buf))
590 return -EFAULT;
591 __handle_sysrq(c, NULL, 0);
592 }
593 return count;
594}
595
596static const struct file_operations proc_sysrq_trigger_operations = {
597 .write = write_sysrq_trigger,
598};
599
600static int __init sysrq_init(void)
601{
602 proc_create("sysrq-trigger", S_IWUSR, NULL, &proc_sysrq_trigger_operations);
603 return 0;
604}
605module_init(sysrq_init);
606#endif