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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,
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);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247}
248static struct sysrq_key_op sysrq_showregs_op = {
249 .handler = sysrq_handle_showregs,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800250 .help_msg = "show-registers(P)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251 .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,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800261 .help_msg = "show-task-states(T)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 .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 Dunlap208b95c2009-01-06 14:41:13 -0800272 .help_msg = "show-blocked-tasks(W)",
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800273 .action_msg = "Show Blocked State",
274 .enable_mask = SYSRQ_ENABLE_DUMP,
275};
276
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100277#ifdef CONFIG_TRACING
278#include <linux/ftrace.h>
279
280static void sysrq_ftrace_dump(int key, struct tty_struct *tty)
281{
282 ftrace_dump();
283}
284static struct sysrq_key_op sysrq_ftrace_dump_op = {
285 .handler = sysrq_ftrace_dump,
286 .help_msg = "dumpZ-ftrace-buffer",
287 .action_msg = "Dump ftrace buffer",
288 .enable_mask = SYSRQ_ENABLE_DUMP,
289};
290#else
291#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)0)
292#endif
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800293
David Howells7d12e782006-10-05 14:55:46 +0100294static void sysrq_handle_showmem(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295{
296 show_mem();
297}
298static struct sysrq_key_op sysrq_showmem_op = {
299 .handler = sysrq_handle_showmem,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800300 .help_msg = "show-memory-usage(M)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 .action_msg = "Show Memory",
302 .enable_mask = SYSRQ_ENABLE_DUMP,
303};
304
Andrew Mortonbf36b902006-03-25 03:07:08 -0800305/*
306 * Signal sysrq helper function. Sends a signal to all user processes.
307 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308static void send_sig_all(int sig)
309{
310 struct task_struct *p;
311
312 for_each_process(p) {
Serge E. Hallynb460cbc2007-10-18 23:39:52 -0700313 if (p->mm && !is_global_init(p))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314 /* Not swapper, init nor kernel thread */
315 force_sig(sig, p);
316 }
317}
318
David Howells7d12e782006-10-05 14:55:46 +0100319static void sysrq_handle_term(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320{
321 send_sig_all(SIGTERM);
322 console_loglevel = 8;
323}
324static struct sysrq_key_op sysrq_term_op = {
325 .handler = sysrq_handle_term,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800326 .help_msg = "terminate-all-tasks(E)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327 .action_msg = "Terminate All Tasks",
328 .enable_mask = SYSRQ_ENABLE_SIGNAL,
329};
330
David Howells65f27f32006-11-22 14:55:48 +0000331static void moom_callback(struct work_struct *ignored)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332{
Mel Gorman0e884602008-04-28 02:12:14 -0700333 out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334}
335
David Howells65f27f32006-11-22 14:55:48 +0000336static DECLARE_WORK(moom_work, moom_callback);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337
David Howells7d12e782006-10-05 14:55:46 +0100338static void sysrq_handle_moom(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339{
340 schedule_work(&moom_work);
341}
342static struct sysrq_key_op sysrq_moom_op = {
343 .handler = sysrq_handle_moom,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800344 .help_msg = "memory-full-oom-kill(F)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345 .action_msg = "Manual OOM execution",
Naohiro Ooiwab4236f82008-10-15 22:01:43 -0700346 .enable_mask = SYSRQ_ENABLE_SIGNAL,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347};
348
David Howells7d12e782006-10-05 14:55:46 +0100349static void sysrq_handle_kill(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350{
351 send_sig_all(SIGKILL);
352 console_loglevel = 8;
353}
354static struct sysrq_key_op sysrq_kill_op = {
355 .handler = sysrq_handle_kill,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800356 .help_msg = "kill-all-tasks(I)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357 .action_msg = "Kill All Tasks",
358 .enable_mask = SYSRQ_ENABLE_SIGNAL,
359};
360
David Howells7d12e782006-10-05 14:55:46 +0100361static void sysrq_handle_unrt(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362{
363 normalize_rt_tasks();
364}
365static struct sysrq_key_op sysrq_unrt_op = {
366 .handler = sysrq_handle_unrt,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800367 .help_msg = "nice-all-RT-tasks(N)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368 .action_msg = "Nice All RT Tasks",
369 .enable_mask = SYSRQ_ENABLE_RTNICE,
370};
371
372/* Key Operations table and lock */
373static DEFINE_SPINLOCK(sysrq_key_table_lock);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800374
375static struct sysrq_key_op *sysrq_key_table[36] = {
376 &sysrq_loglevel_op, /* 0 */
377 &sysrq_loglevel_op, /* 1 */
378 &sysrq_loglevel_op, /* 2 */
379 &sysrq_loglevel_op, /* 3 */
380 &sysrq_loglevel_op, /* 4 */
381 &sysrq_loglevel_op, /* 5 */
382 &sysrq_loglevel_op, /* 6 */
383 &sysrq_loglevel_op, /* 7 */
384 &sysrq_loglevel_op, /* 8 */
385 &sysrq_loglevel_op, /* 9 */
386
387 /*
Randy Dunlapd346cce2007-01-31 23:48:17 -0800388 * a: Don't use for system provided sysrqs, it is handled specially on
389 * sparc and will never arrive.
Andrew Mortonbf36b902006-03-25 03:07:08 -0800390 */
391 NULL, /* a */
392 &sysrq_reboot_op, /* b */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800393 &sysrq_crashdump_op, /* c & ibm_emac driver debug */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800394 &sysrq_showlocks_op, /* d */
395 &sysrq_term_op, /* e */
396 &sysrq_moom_op, /* f */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800397 /* g: May be registered by ppc for kgdb */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800398 NULL, /* g */
399 NULL, /* h */
400 &sysrq_kill_op, /* i */
401 NULL, /* j */
402 &sysrq_SAK_op, /* k */
Rik van Riel5045bca2008-04-29 00:59:21 -0700403#ifdef CONFIG_SMP
404 &sysrq_showallcpus_op, /* l */
405#else
Andrew Mortonbf36b902006-03-25 03:07:08 -0800406 NULL, /* l */
Rik van Riel5045bca2008-04-29 00:59:21 -0700407#endif
Andrew Mortonbf36b902006-03-25 03:07:08 -0800408 &sysrq_showmem_op, /* m */
409 &sysrq_unrt_op, /* n */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800410 /* o: This will often be registered as 'Off' at init time */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800411 NULL, /* o */
412 &sysrq_showregs_op, /* p */
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800413 &sysrq_show_timers_op, /* q */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800414 &sysrq_unraw_op, /* r */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800415 &sysrq_sync_op, /* s */
416 &sysrq_showstate_op, /* t */
417 &sysrq_mountro_op, /* u */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800418 /* v: May be registered at init time by SMP VOYAGER */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800419 NULL, /* v */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800420 &sysrq_showstate_blocked_op, /* w */
421 /* x: May be registered on ppc/powerpc for xmon */
422 NULL, /* x */
David S. Miller93dae5b2008-05-19 23:46:00 -0700423 /* y: May be registered on sparc64 for global register dump */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800424 NULL, /* y */
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100425 &sysrq_ftrace_dump_op, /* z */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426};
427
428/* key2index calculation, -1 on invalid index */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800429static int sysrq_key_table_key2index(int key)
430{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 int retval;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800432
433 if ((key >= '0') && (key <= '9'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434 retval = key - '0';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800435 else if ((key >= 'a') && (key <= 'z'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436 retval = key + 10 - 'a';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800437 else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 retval = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700439 return retval;
440}
441
442/*
443 * get and put functions for the table, exposed to modules.
444 */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800445struct sysrq_key_op *__sysrq_get_key_op(int key)
446{
447 struct sysrq_key_op *op_p = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448 int i;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800449
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450 i = sysrq_key_table_key2index(key);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800451 if (i != -1)
452 op_p = sysrq_key_table[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700453 return op_p;
454}
455
Andrew Mortonbf36b902006-03-25 03:07:08 -0800456static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
457{
458 int i = sysrq_key_table_key2index(key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460 if (i != -1)
461 sysrq_key_table[i] = op_p;
462}
463
464/*
Andrew Mortonbf36b902006-03-25 03:07:08 -0800465 * This is the non-locking version of handle_sysrq. It must/can only be called
466 * by sysrq key handlers, as they are inside of the lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467 */
David Howells7d12e782006-10-05 14:55:46 +0100468void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469{
470 struct sysrq_key_op *op_p;
471 int orig_log_level;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800472 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473 unsigned long flags;
474
475 spin_lock_irqsave(&sysrq_key_table_lock, flags);
Andy Whitcroftfb144ad2009-01-15 13:50:52 -0800476 /*
477 * Raise the apparent loglevel to maximum so that the sysrq header
478 * is shown to provide the user with positive feedback. We do not
479 * simply emit this at KERN_EMERG as that would change message
480 * routing in the consumers of /proc/kmsg.
481 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700482 orig_log_level = console_loglevel;
483 console_loglevel = 7;
484 printk(KERN_INFO "SysRq : ");
485
486 op_p = __sysrq_get_key_op(key);
487 if (op_p) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800488 /*
489 * Should we check for enabled operations (/proc/sysrq-trigger
490 * should not) and is the invoked operation enabled?
491 */
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800492 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800493 printk("%s\n", op_p->action_msg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494 console_loglevel = orig_log_level;
David Howells7d12e782006-10-05 14:55:46 +0100495 op_p->handler(key, tty);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800496 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700497 printk("This sysrq operation is disabled.\n");
Andrew Mortonbf36b902006-03-25 03:07:08 -0800498 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700499 } else {
500 printk("HELP : ");
501 /* Only print the help msg once per handler */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800502 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
503 if (sysrq_key_table[i]) {
504 int j;
505
506 for (j = 0; sysrq_key_table[i] !=
507 sysrq_key_table[j]; j++)
508 ;
509 if (j != i)
510 continue;
511 printk("%s ", sysrq_key_table[i]->help_msg);
512 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513 }
Andrew Mortonbf36b902006-03-25 03:07:08 -0800514 printk("\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515 console_loglevel = orig_log_level;
516 }
517 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
518}
519
520/*
521 * This function is called by the keyboard handler when SysRq is pressed
522 * and any other keycode arrives.
523 */
David Howells7d12e782006-10-05 14:55:46 +0100524void handle_sysrq(int key, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525{
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800526 if (sysrq_on())
527 __handle_sysrq(key, tty, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700528}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800529EXPORT_SYMBOL(handle_sysrq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530
Adrian Bunkcf62ddc2005-11-08 21:39:47 -0800531static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
Andrew Mortonbf36b902006-03-25 03:07:08 -0800532 struct sysrq_key_op *remove_op_p)
533{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700534
535 int retval;
536 unsigned long flags;
537
538 spin_lock_irqsave(&sysrq_key_table_lock, flags);
539 if (__sysrq_get_key_op(key) == remove_op_p) {
540 __sysrq_put_key_op(key, insert_op_p);
541 retval = 0;
542 } else {
543 retval = -1;
544 }
545 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546 return retval;
547}
548
549int register_sysrq_key(int key, struct sysrq_key_op *op_p)
550{
551 return __sysrq_swap_key_ops(key, op_p, NULL);
552}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800553EXPORT_SYMBOL(register_sysrq_key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554
555int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
556{
557 return __sysrq_swap_key_ops(key, NULL, op_p);
558}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700559EXPORT_SYMBOL(unregister_sysrq_key);
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700560
561#ifdef CONFIG_PROC_FS
562/*
563 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
564 */
565static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
566 size_t count, loff_t *ppos)
567{
568 if (count) {
569 char c;
570
571 if (get_user(c, buf))
572 return -EFAULT;
573 __handle_sysrq(c, NULL, 0);
574 }
575 return count;
576}
577
578static const struct file_operations proc_sysrq_trigger_operations = {
579 .write = write_sysrq_trigger,
580};
581
582static int __init sysrq_init(void)
583{
584 proc_create("sysrq-trigger", S_IWUSR, NULL, &proc_sysrq_trigger_operations);
585 return 0;
586}
587module_init(sysrq_init);
588#endif