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Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -07001/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 * Linux Magic System Request Key Hacks
3 *
4 * (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
5 * based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz>
6 *
7 * (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
8 * overhauled to use key registration
9 * based upon discusions in irc://irc.openprojects.net/#kernelnewbies
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070010 *
11 * Copyright (c) 2010 Dmitry Torokhov
12 * Input handler conversion
Linus Torvalds1da177e2005-04-16 15:20:36 -070013 */
14
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070015#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
16
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/sched.h>
18#include <linux/interrupt.h>
19#include <linux/mm.h>
20#include <linux/fs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <linux/mount.h>
22#include <linux/kdev_t.h>
23#include <linux/major.h>
24#include <linux/reboot.h>
25#include <linux/sysrq.h>
26#include <linux/kbd_kern.h>
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -070027#include <linux/proc_fs.h>
Ingo Molnarc1dc0b92009-08-02 11:28:21 +020028#include <linux/nmi.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#include <linux/quotaops.h>
Ingo Molnarcdd6c482009-09-21 12:02:48 +020030#include <linux/perf_event.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031#include <linux/kernel.h>
32#include <linux/module.h>
33#include <linux/suspend.h>
34#include <linux/writeback.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035#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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090041#include <linux/slab.h>
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070042#include <linux/input.h>
Al Viroff01bb482011-09-16 02:31:11 -040043#include <linux/uaccess.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070044
45#include <asm/ptrace.h>
Heiko Carstens2033b0c2006-10-06 16:38:42 +020046#include <asm/irq_regs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070047
48/* Whether we react on sysrq keys or just ignore them */
Andy Whitcroft8c6a98b2011-01-24 09:31:38 -080049static int __read_mostly sysrq_enabled = SYSRQ_DEFAULT_ENABLE;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070050static bool __read_mostly sysrq_always_enabled;
Ingo Molnar5d6f6472006-12-13 00:34:36 -080051
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070052static bool sysrq_on(void)
Ingo Molnar5d6f6472006-12-13 00:34:36 -080053{
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070054 return sysrq_enabled || sysrq_always_enabled;
Ingo Molnar5d6f6472006-12-13 00:34:36 -080055}
56
57/*
58 * A value of 1 means 'all', other nonzero values are an op mask:
59 */
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070060static bool sysrq_on_mask(int mask)
Ingo Molnar5d6f6472006-12-13 00:34:36 -080061{
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070062 return sysrq_always_enabled ||
63 sysrq_enabled == 1 ||
64 (sysrq_enabled & mask);
Ingo Molnar5d6f6472006-12-13 00:34:36 -080065}
66
67static int __init sysrq_always_enabled_setup(char *str)
68{
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070069 sysrq_always_enabled = true;
70 pr_info("sysrq always enabled.\n");
Ingo Molnar5d6f6472006-12-13 00:34:36 -080071
72 return 1;
73}
74
75__setup("sysrq_always_enabled", sysrq_always_enabled_setup);
76
Linus Torvalds1da177e2005-04-16 15:20:36 -070077
Dmitry Torokhov1495cc92010-08-17 21:15:46 -070078static void sysrq_handle_loglevel(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -070079{
80 int i;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070081
Linus Torvalds1da177e2005-04-16 15:20:36 -070082 i = key - '0';
83 console_loglevel = 7;
84 printk("Loglevel set to %d\n", i);
85 console_loglevel = i;
Andrew Mortonbf36b902006-03-25 03:07:08 -080086}
Linus Torvalds1da177e2005-04-16 15:20:36 -070087static struct sysrq_key_op sysrq_loglevel_op = {
88 .handler = sysrq_handle_loglevel,
Randy Dunlap208b95c2009-01-06 14:41:13 -080089 .help_msg = "loglevel(0-9)",
Linus Torvalds1da177e2005-04-16 15:20:36 -070090 .action_msg = "Changing Loglevel",
91 .enable_mask = SYSRQ_ENABLE_LOG,
92};
93
Linus Torvalds1da177e2005-04-16 15:20:36 -070094#ifdef CONFIG_VT
Dmitry Torokhov1495cc92010-08-17 21:15:46 -070095static void sysrq_handle_SAK(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -070096{
Eric W. Biederman8b6312f2007-02-10 01:44:34 -080097 struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
Eric W. Biederman8b6312f2007-02-10 01:44:34 -080098 schedule_work(SAK_work);
Linus Torvalds1da177e2005-04-16 15:20:36 -070099}
100static struct sysrq_key_op sysrq_SAK_op = {
101 .handler = sysrq_handle_SAK,
102 .help_msg = "saK",
103 .action_msg = "SAK",
104 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
105};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800106#else
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700107#define sysrq_SAK_op (*(struct sysrq_key_op *)NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108#endif
109
110#ifdef CONFIG_VT
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700111static void sysrq_handle_unraw(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112{
113 struct kbd_struct *kbd = &kbd_table[fg_console];
114
115 if (kbd)
Bill Nottingham2e8ecb92007-10-16 23:29:38 -0700116 kbd->kbdmode = default_utf8 ? VC_UNICODE : VC_XLATE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117}
118static struct sysrq_key_op sysrq_unraw_op = {
119 .handler = sysrq_handle_unraw,
120 .help_msg = "unRaw",
Bill Nottingham2e8ecb92007-10-16 23:29:38 -0700121 .action_msg = "Keyboard mode set to system default",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
123};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800124#else
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700125#define sysrq_unraw_op (*(struct sysrq_key_op *)NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126#endif /* CONFIG_VT */
127
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700128static void sysrq_handle_crash(int key)
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700129{
Neil Hormand6580a92009-06-17 16:28:17 -0700130 char *killer = NULL;
Hidetoshi Setocab8bd32009-07-29 15:04:14 -0700131
132 panic_on_oops = 1; /* force panic */
133 wmb();
Neil Hormand6580a92009-06-17 16:28:17 -0700134 *killer = 1;
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700135}
Hidetoshi Setocab8bd32009-07-29 15:04:14 -0700136static struct sysrq_key_op sysrq_crash_op = {
Neil Hormand6580a92009-06-17 16:28:17 -0700137 .handler = sysrq_handle_crash,
138 .help_msg = "Crash",
139 .action_msg = "Trigger a crash",
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700140 .enable_mask = SYSRQ_ENABLE_DUMP,
141};
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700142
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700143static void sysrq_handle_reboot(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144{
Peter Zijlstrab2e9c7d2006-09-30 23:28:02 -0700145 lockdep_off();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 local_irq_enable();
Eric W. Biederman4de8b9b2005-07-26 11:51:06 -0600147 emergency_restart();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149static struct sysrq_key_op sysrq_reboot_op = {
150 .handler = sysrq_handle_reboot,
151 .help_msg = "reBoot",
152 .action_msg = "Resetting",
153 .enable_mask = SYSRQ_ENABLE_BOOT,
154};
155
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700156static void sysrq_handle_sync(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157{
158 emergency_sync();
159}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160static struct sysrq_key_op sysrq_sync_op = {
161 .handler = sysrq_handle_sync,
162 .help_msg = "Sync",
163 .action_msg = "Emergency Sync",
164 .enable_mask = SYSRQ_ENABLE_SYNC,
165};
166
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700167static void sysrq_handle_show_timers(int key)
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800168{
169 sysrq_timer_list_show();
170}
171
172static struct sysrq_key_op sysrq_show_timers_op = {
173 .handler = sysrq_handle_show_timers,
174 .help_msg = "show-all-timers(Q)",
Thomas Gleixner322acf62008-10-20 12:33:14 +0200175 .action_msg = "Show clockevent devices & pending hrtimers (no others)",
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800176};
177
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700178static void sysrq_handle_mountro(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179{
180 emergency_remount();
181}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182static struct sysrq_key_op sysrq_mountro_op = {
183 .handler = sysrq_handle_mountro,
184 .help_msg = "Unmount",
185 .action_msg = "Emergency Remount R/O",
186 .enable_mask = SYSRQ_ENABLE_REMOUNT,
187};
188
Ingo Molnar8c645802006-07-03 00:24:56 -0700189#ifdef CONFIG_LOCKDEP
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700190static void sysrq_handle_showlocks(int key)
Ingo Molnarde5097c2006-01-09 15:59:21 -0800191{
Ingo Molnar9a11b49a2006-07-03 00:24:33 -0700192 debug_show_all_locks();
Ingo Molnarde5097c2006-01-09 15:59:21 -0800193}
Ingo Molnar8c645802006-07-03 00:24:56 -0700194
Ingo Molnarde5097c2006-01-09 15:59:21 -0800195static struct sysrq_key_op sysrq_showlocks_op = {
196 .handler = sysrq_handle_showlocks,
197 .help_msg = "show-all-locks(D)",
198 .action_msg = "Show Locks Held",
199};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800200#else
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700201#define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL)
Ingo Molnarde5097c2006-01-09 15:59:21 -0800202#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203
Rik van Riel5045bca2008-04-29 00:59:21 -0700204#ifdef CONFIG_SMP
205static DEFINE_SPINLOCK(show_lock);
206
207static void showacpu(void *dummy)
208{
209 unsigned long flags;
210
211 /* Idle CPUs have no interesting backtrace. */
212 if (idle_cpu(smp_processor_id()))
213 return;
214
215 spin_lock_irqsave(&show_lock, flags);
216 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
217 show_stack(NULL, NULL);
218 spin_unlock_irqrestore(&show_lock, flags);
219}
220
221static void sysrq_showregs_othercpus(struct work_struct *dummy)
222{
Ingo Molnar8b604d52008-06-27 11:52:45 +0200223 smp_call_function(showacpu, NULL, 0);
Rik van Riel5045bca2008-04-29 00:59:21 -0700224}
225
226static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
227
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700228static void sysrq_handle_showallcpus(int key)
Rik van Riel5045bca2008-04-29 00:59:21 -0700229{
Ingo Molnar47cab6a2009-08-03 09:31:54 +0200230 /*
231 * Fall back to the workqueue based printing if the
232 * backtrace printing did not succeed or the
233 * architecture has no support for it:
234 */
235 if (!trigger_all_cpu_backtrace()) {
236 struct pt_regs *regs = get_irq_regs();
237
238 if (regs) {
239 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
240 show_regs(regs);
241 }
242 schedule_work(&sysrq_showallcpus);
243 }
Rik van Riel5045bca2008-04-29 00:59:21 -0700244}
245
246static struct sysrq_key_op sysrq_showallcpus_op = {
247 .handler = sysrq_handle_showallcpus,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800248 .help_msg = "show-backtrace-all-active-cpus(L)",
Rik van Riel5045bca2008-04-29 00:59:21 -0700249 .action_msg = "Show backtrace of all active CPUs",
250 .enable_mask = SYSRQ_ENABLE_DUMP,
251};
252#endif
253
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700254static void sysrq_handle_showregs(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255{
David Howells7d12e782006-10-05 14:55:46 +0100256 struct pt_regs *regs = get_irq_regs();
257 if (regs)
258 show_regs(regs);
Ingo Molnarcdd6c482009-09-21 12:02:48 +0200259 perf_event_print_debug();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260}
261static struct sysrq_key_op sysrq_showregs_op = {
262 .handler = sysrq_handle_showregs,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800263 .help_msg = "show-registers(P)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264 .action_msg = "Show Regs",
265 .enable_mask = SYSRQ_ENABLE_DUMP,
266};
267
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700268static void sysrq_handle_showstate(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269{
270 show_state();
271}
272static struct sysrq_key_op sysrq_showstate_op = {
273 .handler = sysrq_handle_showstate,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800274 .help_msg = "show-task-states(T)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275 .action_msg = "Show State",
276 .enable_mask = SYSRQ_ENABLE_DUMP,
277};
278
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700279static void sysrq_handle_showstate_blocked(int key)
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800280{
281 show_state_filter(TASK_UNINTERRUPTIBLE);
282}
283static struct sysrq_key_op sysrq_showstate_blocked_op = {
284 .handler = sysrq_handle_showstate_blocked,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800285 .help_msg = "show-blocked-tasks(W)",
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800286 .action_msg = "Show Blocked State",
287 .enable_mask = SYSRQ_ENABLE_DUMP,
288};
289
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100290#ifdef CONFIG_TRACING
291#include <linux/ftrace.h>
292
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700293static void sysrq_ftrace_dump(int key)
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100294{
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200295 ftrace_dump(DUMP_ALL);
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100296}
297static struct sysrq_key_op sysrq_ftrace_dump_op = {
298 .handler = sysrq_ftrace_dump,
Randy Dunlap3871f2f2008-12-24 16:06:57 -0800299 .help_msg = "dump-ftrace-buffer(Z)",
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100300 .action_msg = "Dump ftrace buffer",
301 .enable_mask = SYSRQ_ENABLE_DUMP,
302};
303#else
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700304#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100305#endif
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800306
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700307static void sysrq_handle_showmem(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308{
David Rientjesb2b755b2011-03-24 15:18:15 -0700309 show_mem(0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310}
311static struct sysrq_key_op sysrq_showmem_op = {
312 .handler = sysrq_handle_showmem,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800313 .help_msg = "show-memory-usage(M)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314 .action_msg = "Show Memory",
315 .enable_mask = SYSRQ_ENABLE_DUMP,
316};
317
Andrew Mortonbf36b902006-03-25 03:07:08 -0800318/*
319 * Signal sysrq helper function. Sends a signal to all user processes.
320 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321static void send_sig_all(int sig)
322{
323 struct task_struct *p;
324
325 for_each_process(p) {
Serge E. Hallynb460cbc2007-10-18 23:39:52 -0700326 if (p->mm && !is_global_init(p))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327 /* Not swapper, init nor kernel thread */
328 force_sig(sig, p);
329 }
330}
331
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700332static void sysrq_handle_term(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333{
334 send_sig_all(SIGTERM);
335 console_loglevel = 8;
336}
337static struct sysrq_key_op sysrq_term_op = {
338 .handler = sysrq_handle_term,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800339 .help_msg = "terminate-all-tasks(E)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 .action_msg = "Terminate All Tasks",
341 .enable_mask = SYSRQ_ENABLE_SIGNAL,
342};
343
David Howells65f27f32006-11-22 14:55:48 +0000344static void moom_callback(struct work_struct *ignored)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345{
KAMEZAWA Hiroyuki4365a562009-12-15 16:45:33 -0800346 out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347}
348
David Howells65f27f32006-11-22 14:55:48 +0000349static DECLARE_WORK(moom_work, moom_callback);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700351static void sysrq_handle_moom(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352{
353 schedule_work(&moom_work);
354}
355static struct sysrq_key_op sysrq_moom_op = {
356 .handler = sysrq_handle_moom,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800357 .help_msg = "memory-full-oom-kill(F)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358 .action_msg = "Manual OOM execution",
Naohiro Ooiwab4236f82008-10-15 22:01:43 -0700359 .enable_mask = SYSRQ_ENABLE_SIGNAL,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360};
361
Eric Sandeenc2d75432009-03-31 15:23:46 -0700362#ifdef CONFIG_BLOCK
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700363static void sysrq_handle_thaw(int key)
Eric Sandeenc2d75432009-03-31 15:23:46 -0700364{
365 emergency_thaw_all();
366}
367static struct sysrq_key_op sysrq_thaw_op = {
368 .handler = sysrq_handle_thaw,
369 .help_msg = "thaw-filesystems(J)",
370 .action_msg = "Emergency Thaw of all frozen filesystems",
371 .enable_mask = SYSRQ_ENABLE_SIGNAL,
372};
373#endif
374
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700375static void sysrq_handle_kill(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376{
377 send_sig_all(SIGKILL);
378 console_loglevel = 8;
379}
380static struct sysrq_key_op sysrq_kill_op = {
381 .handler = sysrq_handle_kill,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800382 .help_msg = "kill-all-tasks(I)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383 .action_msg = "Kill All Tasks",
384 .enable_mask = SYSRQ_ENABLE_SIGNAL,
385};
386
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700387static void sysrq_handle_unrt(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388{
389 normalize_rt_tasks();
390}
391static struct sysrq_key_op sysrq_unrt_op = {
392 .handler = sysrq_handle_unrt,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800393 .help_msg = "nice-all-RT-tasks(N)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 .action_msg = "Nice All RT Tasks",
395 .enable_mask = SYSRQ_ENABLE_RTNICE,
396};
397
398/* Key Operations table and lock */
399static DEFINE_SPINLOCK(sysrq_key_table_lock);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800400
401static struct sysrq_key_op *sysrq_key_table[36] = {
402 &sysrq_loglevel_op, /* 0 */
403 &sysrq_loglevel_op, /* 1 */
404 &sysrq_loglevel_op, /* 2 */
405 &sysrq_loglevel_op, /* 3 */
406 &sysrq_loglevel_op, /* 4 */
407 &sysrq_loglevel_op, /* 5 */
408 &sysrq_loglevel_op, /* 6 */
409 &sysrq_loglevel_op, /* 7 */
410 &sysrq_loglevel_op, /* 8 */
411 &sysrq_loglevel_op, /* 9 */
412
413 /*
Randy Dunlapd346cce2007-01-31 23:48:17 -0800414 * a: Don't use for system provided sysrqs, it is handled specially on
415 * sparc and will never arrive.
Andrew Mortonbf36b902006-03-25 03:07:08 -0800416 */
417 NULL, /* a */
418 &sysrq_reboot_op, /* b */
Hidetoshi Setocab8bd32009-07-29 15:04:14 -0700419 &sysrq_crash_op, /* c & ibm_emac driver debug */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800420 &sysrq_showlocks_op, /* d */
421 &sysrq_term_op, /* e */
422 &sysrq_moom_op, /* f */
Jason Wessel364b5b72009-05-13 21:56:59 -0500423 /* g: May be registered for the kernel debugger */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800424 NULL, /* g */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700425 NULL, /* h - reserved for help */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800426 &sysrq_kill_op, /* i */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700427#ifdef CONFIG_BLOCK
428 &sysrq_thaw_op, /* j */
429#else
Andrew Mortonbf36b902006-03-25 03:07:08 -0800430 NULL, /* j */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700431#endif
Andrew Mortonbf36b902006-03-25 03:07:08 -0800432 &sysrq_SAK_op, /* k */
Rik van Riel5045bca2008-04-29 00:59:21 -0700433#ifdef CONFIG_SMP
434 &sysrq_showallcpus_op, /* l */
435#else
Andrew Mortonbf36b902006-03-25 03:07:08 -0800436 NULL, /* l */
Rik van Riel5045bca2008-04-29 00:59:21 -0700437#endif
Andrew Mortonbf36b902006-03-25 03:07:08 -0800438 &sysrq_showmem_op, /* m */
439 &sysrq_unrt_op, /* n */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800440 /* o: This will often be registered as 'Off' at init time */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800441 NULL, /* o */
442 &sysrq_showregs_op, /* p */
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800443 &sysrq_show_timers_op, /* q */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800444 &sysrq_unraw_op, /* r */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800445 &sysrq_sync_op, /* s */
446 &sysrq_showstate_op, /* t */
447 &sysrq_mountro_op, /* u */
Jason Wessel364b5b72009-05-13 21:56:59 -0500448 /* v: May be registered for frame buffer console restore */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800449 NULL, /* v */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800450 &sysrq_showstate_blocked_op, /* w */
451 /* x: May be registered on ppc/powerpc for xmon */
452 NULL, /* x */
David S. Miller93dae5b2008-05-19 23:46:00 -0700453 /* y: May be registered on sparc64 for global register dump */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800454 NULL, /* y */
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100455 &sysrq_ftrace_dump_op, /* z */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456};
457
458/* key2index calculation, -1 on invalid index */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800459static int sysrq_key_table_key2index(int key)
460{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461 int retval;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800462
463 if ((key >= '0') && (key <= '9'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464 retval = key - '0';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800465 else if ((key >= 'a') && (key <= 'z'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466 retval = key + 10 - 'a';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800467 else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468 retval = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469 return retval;
470}
471
472/*
473 * get and put functions for the table, exposed to modules.
474 */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800475struct sysrq_key_op *__sysrq_get_key_op(int key)
476{
477 struct sysrq_key_op *op_p = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700478 int i;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800479
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480 i = sysrq_key_table_key2index(key);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800481 if (i != -1)
482 op_p = sysrq_key_table[i];
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700483
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484 return op_p;
485}
486
Andrew Mortonbf36b902006-03-25 03:07:08 -0800487static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
488{
489 int i = sysrq_key_table_key2index(key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491 if (i != -1)
492 sysrq_key_table[i] = op_p;
493}
494
Dmitry Torokhovf3353972010-08-17 21:15:47 -0700495void __handle_sysrq(int key, bool check_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700496{
497 struct sysrq_key_op *op_p;
498 int orig_log_level;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800499 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500 unsigned long flags;
501
502 spin_lock_irqsave(&sysrq_key_table_lock, flags);
Andy Whitcroftfb144ad2009-01-15 13:50:52 -0800503 /*
504 * Raise the apparent loglevel to maximum so that the sysrq header
505 * is shown to provide the user with positive feedback. We do not
506 * simply emit this at KERN_EMERG as that would change message
507 * routing in the consumers of /proc/kmsg.
508 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700509 orig_log_level = console_loglevel;
510 console_loglevel = 7;
511 printk(KERN_INFO "SysRq : ");
512
513 op_p = __sysrq_get_key_op(key);
514 if (op_p) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800515 /*
516 * Should we check for enabled operations (/proc/sysrq-trigger
517 * should not) and is the invoked operation enabled?
518 */
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800519 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800520 printk("%s\n", op_p->action_msg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521 console_loglevel = orig_log_level;
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700522 op_p->handler(key);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800523 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524 printk("This sysrq operation is disabled.\n");
Andrew Mortonbf36b902006-03-25 03:07:08 -0800525 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526 } else {
527 printk("HELP : ");
528 /* Only print the help msg once per handler */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800529 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
530 if (sysrq_key_table[i]) {
531 int j;
532
533 for (j = 0; sysrq_key_table[i] !=
534 sysrq_key_table[j]; j++)
535 ;
536 if (j != i)
537 continue;
538 printk("%s ", sysrq_key_table[i]->help_msg);
539 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540 }
Andrew Mortonbf36b902006-03-25 03:07:08 -0800541 printk("\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542 console_loglevel = orig_log_level;
543 }
544 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
545}
546
Dmitry Torokhovf3353972010-08-17 21:15:47 -0700547void handle_sysrq(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548{
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800549 if (sysrq_on())
Dmitry Torokhovf3353972010-08-17 21:15:47 -0700550 __handle_sysrq(key, true);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800552EXPORT_SYMBOL(handle_sysrq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700554#ifdef CONFIG_INPUT
555
556/* Simple translation table for the SysRq keys */
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800557static const unsigned char sysrq_xlate[KEY_CNT] =
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700558 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */
559 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */
560 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */
561 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */
562 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */
563 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
564 "\r\000/"; /* 0x60 - 0x6f */
565
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800566struct sysrq_state {
567 struct input_handle handle;
568 struct work_struct reinject_work;
569 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
570 unsigned int alt;
571 unsigned int alt_use;
572 bool active;
573 bool need_reinject;
Dmitry Torokhov7ab7b5a2011-02-02 22:59:54 -0800574 bool reinjecting;
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800575};
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700576
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800577static void sysrq_reinject_alt_sysrq(struct work_struct *work)
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700578{
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800579 struct sysrq_state *sysrq =
580 container_of(work, struct sysrq_state, reinject_work);
581 struct input_handle *handle = &sysrq->handle;
582 unsigned int alt_code = sysrq->alt_use;
583
584 if (sysrq->need_reinject) {
Dmitry Torokhov7ab7b5a2011-02-02 22:59:54 -0800585 /* we do not want the assignment to be reordered */
586 sysrq->reinjecting = true;
587 mb();
588
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800589 /* Simulate press and release of Alt + SysRq */
590 input_inject_event(handle, EV_KEY, alt_code, 1);
591 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
592 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
593
594 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
595 input_inject_event(handle, EV_KEY, alt_code, 0);
596 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
Dmitry Torokhov7ab7b5a2011-02-02 22:59:54 -0800597
598 mb();
599 sysrq->reinjecting = false;
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800600 }
601}
602
603static bool sysrq_filter(struct input_handle *handle,
604 unsigned int type, unsigned int code, int value)
605{
606 struct sysrq_state *sysrq = handle->private;
607 bool was_active = sysrq->active;
Dmitry Torokhov1966cb22010-09-29 18:04:21 -0700608 bool suppress;
609
Dmitry Torokhov7ab7b5a2011-02-02 22:59:54 -0800610 /*
611 * Do not filter anything if we are in the process of re-injecting
612 * Alt+SysRq combination.
613 */
614 if (sysrq->reinjecting)
615 return false;
616
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800617 switch (type) {
Dmitry Torokhov1966cb22010-09-29 18:04:21 -0700618
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800619 case EV_SYN:
620 suppress = false;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700621 break;
622
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800623 case EV_KEY:
624 switch (code) {
625
626 case KEY_LEFTALT:
627 case KEY_RIGHTALT:
628 if (!value) {
629 /* One of ALTs is being released */
630 if (sysrq->active && code == sysrq->alt_use)
631 sysrq->active = false;
632
633 sysrq->alt = KEY_RESERVED;
634
635 } else if (value != 2) {
636 sysrq->alt = code;
637 sysrq->need_reinject = false;
638 }
639 break;
640
641 case KEY_SYSRQ:
642 if (value == 1 && sysrq->alt != KEY_RESERVED) {
643 sysrq->active = true;
644 sysrq->alt_use = sysrq->alt;
645 /*
646 * If nothing else will be pressed we'll need
Dmitry Torokhov7ab7b5a2011-02-02 22:59:54 -0800647 * to re-inject Alt-SysRq keysroke.
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800648 */
649 sysrq->need_reinject = true;
650 }
651
652 /*
653 * Pretend that sysrq was never pressed at all. This
654 * is needed to properly handle KGDB which will try
655 * to release all keys after exiting debugger. If we
656 * do not clear key bit it KGDB will end up sending
657 * release events for Alt and SysRq, potentially
658 * triggering print screen function.
659 */
660 if (sysrq->active)
661 clear_bit(KEY_SYSRQ, handle->dev->key);
662
663 break;
664
665 default:
666 if (sysrq->active && value && value != 2) {
667 sysrq->need_reinject = false;
668 __handle_sysrq(sysrq_xlate[code], true);
669 }
670 break;
671 }
672
673 suppress = sysrq->active;
674
675 if (!sysrq->active) {
676 /*
677 * If we are not suppressing key presses keep track of
678 * keyboard state so we can release keys that have been
679 * pressed before entering SysRq mode.
680 */
681 if (value)
682 set_bit(code, sysrq->key_down);
683 else
684 clear_bit(code, sysrq->key_down);
685
686 if (was_active)
687 schedule_work(&sysrq->reinject_work);
688
689 } else if (value == 0 &&
690 test_and_clear_bit(code, sysrq->key_down)) {
691 /*
692 * Pass on release events for keys that was pressed before
693 * entering SysRq mode.
694 */
695 suppress = false;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700696 }
697 break;
698
699 default:
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800700 suppress = sysrq->active;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700701 break;
702 }
703
Dmitry Torokhov1966cb22010-09-29 18:04:21 -0700704 return suppress;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700705}
706
707static int sysrq_connect(struct input_handler *handler,
708 struct input_dev *dev,
709 const struct input_device_id *id)
710{
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800711 struct sysrq_state *sysrq;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700712 int error;
713
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800714 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);
715 if (!sysrq)
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700716 return -ENOMEM;
717
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800718 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700719
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800720 sysrq->handle.dev = dev;
721 sysrq->handle.handler = handler;
722 sysrq->handle.name = "sysrq";
723 sysrq->handle.private = sysrq;
724
725 error = input_register_handle(&sysrq->handle);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700726 if (error) {
727 pr_err("Failed to register input sysrq handler, error %d\n",
728 error);
729 goto err_free;
730 }
731
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800732 error = input_open_device(&sysrq->handle);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700733 if (error) {
734 pr_err("Failed to open input device, error %d\n", error);
735 goto err_unregister;
736 }
737
738 return 0;
739
740 err_unregister:
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800741 input_unregister_handle(&sysrq->handle);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700742 err_free:
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800743 kfree(sysrq);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700744 return error;
745}
746
747static void sysrq_disconnect(struct input_handle *handle)
748{
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800749 struct sysrq_state *sysrq = handle->private;
750
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700751 input_close_device(handle);
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800752 cancel_work_sync(&sysrq->reinject_work);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700753 input_unregister_handle(handle);
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800754 kfree(sysrq);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700755}
756
757/*
Dmitry Torokhov1966cb22010-09-29 18:04:21 -0700758 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all
759 * keyboards have SysRq key predefined and so user may add it to keymap
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700760 * later, but we expect all such keyboards to have left alt.
761 */
762static const struct input_device_id sysrq_ids[] = {
763 {
764 .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
765 INPUT_DEVICE_ID_MATCH_KEYBIT,
766 .evbit = { BIT_MASK(EV_KEY) },
767 .keybit = { BIT_MASK(KEY_LEFTALT) },
768 },
769 { },
770};
771
772static struct input_handler sysrq_handler = {
773 .filter = sysrq_filter,
774 .connect = sysrq_connect,
775 .disconnect = sysrq_disconnect,
776 .name = "sysrq",
777 .id_table = sysrq_ids,
778};
779
780static bool sysrq_handler_registered;
781
782static inline void sysrq_register_handler(void)
783{
784 int error;
785
786 error = input_register_handler(&sysrq_handler);
787 if (error)
788 pr_err("Failed to register input handler, error %d", error);
789 else
790 sysrq_handler_registered = true;
791}
792
793static inline void sysrq_unregister_handler(void)
794{
795 if (sysrq_handler_registered) {
796 input_unregister_handler(&sysrq_handler);
797 sysrq_handler_registered = false;
798 }
799}
800
801#else
802
803static inline void sysrq_register_handler(void)
804{
805}
806
807static inline void sysrq_unregister_handler(void)
808{
809}
810
811#endif /* CONFIG_INPUT */
812
813int sysrq_toggle_support(int enable_mask)
814{
815 bool was_enabled = sysrq_on();
816
817 sysrq_enabled = enable_mask;
818
819 if (was_enabled != sysrq_on()) {
820 if (sysrq_on())
821 sysrq_register_handler();
822 else
823 sysrq_unregister_handler();
824 }
825
826 return 0;
827}
828
Adrian Bunkcf62ddc2005-11-08 21:39:47 -0800829static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
Andrew Mortonbf36b902006-03-25 03:07:08 -0800830 struct sysrq_key_op *remove_op_p)
831{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832 int retval;
833 unsigned long flags;
834
835 spin_lock_irqsave(&sysrq_key_table_lock, flags);
836 if (__sysrq_get_key_op(key) == remove_op_p) {
837 __sysrq_put_key_op(key, insert_op_p);
838 retval = 0;
839 } else {
840 retval = -1;
841 }
842 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843 return retval;
844}
845
846int register_sysrq_key(int key, struct sysrq_key_op *op_p)
847{
848 return __sysrq_swap_key_ops(key, op_p, NULL);
849}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800850EXPORT_SYMBOL(register_sysrq_key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700851
852int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
853{
854 return __sysrq_swap_key_ops(key, NULL, op_p);
855}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700856EXPORT_SYMBOL(unregister_sysrq_key);
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700857
858#ifdef CONFIG_PROC_FS
859/*
860 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
861 */
862static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
863 size_t count, loff_t *ppos)
864{
865 if (count) {
866 char c;
867
868 if (get_user(c, buf))
869 return -EFAULT;
Dmitry Torokhovf3353972010-08-17 21:15:47 -0700870 __handle_sysrq(c, false);
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700871 }
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700872
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700873 return count;
874}
875
876static const struct file_operations proc_sysrq_trigger_operations = {
877 .write = write_sysrq_trigger,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200878 .llseek = noop_llseek,
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700879};
880
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700881static void sysrq_init_procfs(void)
882{
883 if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
884 &proc_sysrq_trigger_operations))
885 pr_err("Failed to register proc interface\n");
886}
887
888#else
889
890static inline void sysrq_init_procfs(void)
891{
892}
893
894#endif /* CONFIG_PROC_FS */
895
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700896static int __init sysrq_init(void)
897{
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700898 sysrq_init_procfs();
899
900 if (sysrq_on())
901 sysrq_register_handler();
902
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700903 return 0;
904}
905module_init(sysrq_init);