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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{
Alan Cox079c9532012-02-28 14:49:23 +0000113 vt_reset_unicode(fg_console);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114}
Alan Cox079c9532012-02-28 14:49:23 +0000115
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116static struct sysrq_key_op sysrq_unraw_op = {
117 .handler = sysrq_handle_unraw,
118 .help_msg = "unRaw",
Bill Nottingham2e8ecb92007-10-16 23:29:38 -0700119 .action_msg = "Keyboard mode set to system default",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
121};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800122#else
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700123#define sysrq_unraw_op (*(struct sysrq_key_op *)NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124#endif /* CONFIG_VT */
125
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700126static void sysrq_handle_crash(int key)
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700127{
Neil Hormand6580a92009-06-17 16:28:17 -0700128 char *killer = NULL;
Hidetoshi Setocab8bd32009-07-29 15:04:14 -0700129
130 panic_on_oops = 1; /* force panic */
131 wmb();
Neil Hormand6580a92009-06-17 16:28:17 -0700132 *killer = 1;
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700133}
Hidetoshi Setocab8bd32009-07-29 15:04:14 -0700134static struct sysrq_key_op sysrq_crash_op = {
Neil Hormand6580a92009-06-17 16:28:17 -0700135 .handler = sysrq_handle_crash,
136 .help_msg = "Crash",
137 .action_msg = "Trigger a crash",
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700138 .enable_mask = SYSRQ_ENABLE_DUMP,
139};
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700140
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700141static void sysrq_handle_reboot(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142{
Peter Zijlstrab2e9c7d2006-09-30 23:28:02 -0700143 lockdep_off();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144 local_irq_enable();
Eric W. Biederman4de8b9b2005-07-26 11:51:06 -0600145 emergency_restart();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147static struct sysrq_key_op sysrq_reboot_op = {
148 .handler = sysrq_handle_reboot,
149 .help_msg = "reBoot",
150 .action_msg = "Resetting",
151 .enable_mask = SYSRQ_ENABLE_BOOT,
152};
153
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700154static void sysrq_handle_sync(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155{
156 emergency_sync();
157}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158static struct sysrq_key_op sysrq_sync_op = {
159 .handler = sysrq_handle_sync,
160 .help_msg = "Sync",
161 .action_msg = "Emergency Sync",
162 .enable_mask = SYSRQ_ENABLE_SYNC,
163};
164
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700165static void sysrq_handle_show_timers(int key)
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800166{
167 sysrq_timer_list_show();
168}
169
170static struct sysrq_key_op sysrq_show_timers_op = {
171 .handler = sysrq_handle_show_timers,
172 .help_msg = "show-all-timers(Q)",
Thomas Gleixner322acf62008-10-20 12:33:14 +0200173 .action_msg = "Show clockevent devices & pending hrtimers (no others)",
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800174};
175
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700176static void sysrq_handle_mountro(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177{
178 emergency_remount();
179}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180static struct sysrq_key_op sysrq_mountro_op = {
181 .handler = sysrq_handle_mountro,
182 .help_msg = "Unmount",
183 .action_msg = "Emergency Remount R/O",
184 .enable_mask = SYSRQ_ENABLE_REMOUNT,
185};
186
Ingo Molnar8c645802006-07-03 00:24:56 -0700187#ifdef CONFIG_LOCKDEP
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700188static void sysrq_handle_showlocks(int key)
Ingo Molnarde5097c2006-01-09 15:59:21 -0800189{
Ingo Molnar9a11b49a2006-07-03 00:24:33 -0700190 debug_show_all_locks();
Ingo Molnarde5097c2006-01-09 15:59:21 -0800191}
Ingo Molnar8c645802006-07-03 00:24:56 -0700192
Ingo Molnarde5097c2006-01-09 15:59:21 -0800193static struct sysrq_key_op sysrq_showlocks_op = {
194 .handler = sysrq_handle_showlocks,
195 .help_msg = "show-all-locks(D)",
196 .action_msg = "Show Locks Held",
197};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800198#else
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700199#define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL)
Ingo Molnarde5097c2006-01-09 15:59:21 -0800200#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201
Rik van Riel5045bca2008-04-29 00:59:21 -0700202#ifdef CONFIG_SMP
203static DEFINE_SPINLOCK(show_lock);
204
205static void showacpu(void *dummy)
206{
207 unsigned long flags;
208
209 /* Idle CPUs have no interesting backtrace. */
210 if (idle_cpu(smp_processor_id()))
211 return;
212
213 spin_lock_irqsave(&show_lock, flags);
214 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
215 show_stack(NULL, NULL);
216 spin_unlock_irqrestore(&show_lock, flags);
217}
218
219static void sysrq_showregs_othercpus(struct work_struct *dummy)
220{
Ingo Molnar8b604d52008-06-27 11:52:45 +0200221 smp_call_function(showacpu, NULL, 0);
Rik van Riel5045bca2008-04-29 00:59:21 -0700222}
223
224static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
225
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700226static void sysrq_handle_showallcpus(int key)
Rik van Riel5045bca2008-04-29 00:59:21 -0700227{
Ingo Molnar47cab6a2009-08-03 09:31:54 +0200228 /*
229 * Fall back to the workqueue based printing if the
230 * backtrace printing did not succeed or the
231 * architecture has no support for it:
232 */
233 if (!trigger_all_cpu_backtrace()) {
234 struct pt_regs *regs = get_irq_regs();
235
236 if (regs) {
237 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
238 show_regs(regs);
239 }
240 schedule_work(&sysrq_showallcpus);
241 }
Rik van Riel5045bca2008-04-29 00:59:21 -0700242}
243
244static struct sysrq_key_op sysrq_showallcpus_op = {
245 .handler = sysrq_handle_showallcpus,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800246 .help_msg = "show-backtrace-all-active-cpus(L)",
Rik van Riel5045bca2008-04-29 00:59:21 -0700247 .action_msg = "Show backtrace of all active CPUs",
248 .enable_mask = SYSRQ_ENABLE_DUMP,
249};
250#endif
251
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700252static void sysrq_handle_showregs(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253{
David Howells7d12e782006-10-05 14:55:46 +0100254 struct pt_regs *regs = get_irq_regs();
255 if (regs)
256 show_regs(regs);
Ingo Molnarcdd6c482009-09-21 12:02:48 +0200257 perf_event_print_debug();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258}
259static struct sysrq_key_op sysrq_showregs_op = {
260 .handler = sysrq_handle_showregs,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800261 .help_msg = "show-registers(P)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 .action_msg = "Show Regs",
263 .enable_mask = SYSRQ_ENABLE_DUMP,
264};
265
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700266static void sysrq_handle_showstate(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267{
268 show_state();
269}
270static struct sysrq_key_op sysrq_showstate_op = {
271 .handler = sysrq_handle_showstate,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800272 .help_msg = "show-task-states(T)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273 .action_msg = "Show State",
274 .enable_mask = SYSRQ_ENABLE_DUMP,
275};
276
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700277static void sysrq_handle_showstate_blocked(int key)
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800278{
279 show_state_filter(TASK_UNINTERRUPTIBLE);
280}
281static struct sysrq_key_op sysrq_showstate_blocked_op = {
282 .handler = sysrq_handle_showstate_blocked,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800283 .help_msg = "show-blocked-tasks(W)",
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800284 .action_msg = "Show Blocked State",
285 .enable_mask = SYSRQ_ENABLE_DUMP,
286};
287
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100288#ifdef CONFIG_TRACING
289#include <linux/ftrace.h>
290
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700291static void sysrq_ftrace_dump(int key)
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100292{
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200293 ftrace_dump(DUMP_ALL);
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100294}
295static struct sysrq_key_op sysrq_ftrace_dump_op = {
296 .handler = sysrq_ftrace_dump,
Randy Dunlap3871f2f2008-12-24 16:06:57 -0800297 .help_msg = "dump-ftrace-buffer(Z)",
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100298 .action_msg = "Dump ftrace buffer",
299 .enable_mask = SYSRQ_ENABLE_DUMP,
300};
301#else
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700302#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100303#endif
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800304
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700305static void sysrq_handle_showmem(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306{
David Rientjesb2b755b2011-03-24 15:18:15 -0700307 show_mem(0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308}
309static struct sysrq_key_op sysrq_showmem_op = {
310 .handler = sysrq_handle_showmem,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800311 .help_msg = "show-memory-usage(M)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312 .action_msg = "Show Memory",
313 .enable_mask = SYSRQ_ENABLE_DUMP,
314};
315
Andrew Mortonbf36b902006-03-25 03:07:08 -0800316/*
317 * Signal sysrq helper function. Sends a signal to all user processes.
318 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319static void send_sig_all(int sig)
320{
321 struct task_struct *p;
322
Anton Vorontsove502bab2012-02-07 10:49:39 +0400323 read_lock(&tasklist_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324 for_each_process(p) {
Anton Vorontsovd3a532a2012-02-07 10:49:51 +0400325 if (p->flags & PF_KTHREAD)
326 continue;
327 if (is_global_init(p))
328 continue;
329
Anton Vorontsovb82c3282012-04-05 14:25:05 -0700330 do_send_sig_info(sig, SEND_SIG_FORCED, p, true);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 }
Anton Vorontsove502bab2012-02-07 10:49:39 +0400332 read_unlock(&tasklist_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333}
334
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700335static void sysrq_handle_term(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336{
337 send_sig_all(SIGTERM);
338 console_loglevel = 8;
339}
340static struct sysrq_key_op sysrq_term_op = {
341 .handler = sysrq_handle_term,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800342 .help_msg = "terminate-all-tasks(E)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343 .action_msg = "Terminate All Tasks",
344 .enable_mask = SYSRQ_ENABLE_SIGNAL,
345};
346
David Howells65f27f32006-11-22 14:55:48 +0000347static void moom_callback(struct work_struct *ignored)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348{
David Rientjes53186092012-11-14 01:15:19 -0800349 out_of_memory(node_zonelist(first_online_node, GFP_KERNEL), GFP_KERNEL,
350 0, NULL, true);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351}
352
David Howells65f27f32006-11-22 14:55:48 +0000353static DECLARE_WORK(moom_work, moom_callback);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700355static void sysrq_handle_moom(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356{
357 schedule_work(&moom_work);
358}
359static struct sysrq_key_op sysrq_moom_op = {
360 .handler = sysrq_handle_moom,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800361 .help_msg = "memory-full-oom-kill(F)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362 .action_msg = "Manual OOM execution",
Naohiro Ooiwab4236f82008-10-15 22:01:43 -0700363 .enable_mask = SYSRQ_ENABLE_SIGNAL,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364};
365
Eric Sandeenc2d75432009-03-31 15:23:46 -0700366#ifdef CONFIG_BLOCK
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700367static void sysrq_handle_thaw(int key)
Eric Sandeenc2d75432009-03-31 15:23:46 -0700368{
369 emergency_thaw_all();
370}
371static struct sysrq_key_op sysrq_thaw_op = {
372 .handler = sysrq_handle_thaw,
373 .help_msg = "thaw-filesystems(J)",
374 .action_msg = "Emergency Thaw of all frozen filesystems",
375 .enable_mask = SYSRQ_ENABLE_SIGNAL,
376};
377#endif
378
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700379static void sysrq_handle_kill(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380{
381 send_sig_all(SIGKILL);
382 console_loglevel = 8;
383}
384static struct sysrq_key_op sysrq_kill_op = {
385 .handler = sysrq_handle_kill,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800386 .help_msg = "kill-all-tasks(I)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387 .action_msg = "Kill All Tasks",
388 .enable_mask = SYSRQ_ENABLE_SIGNAL,
389};
390
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700391static void sysrq_handle_unrt(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392{
393 normalize_rt_tasks();
394}
395static struct sysrq_key_op sysrq_unrt_op = {
396 .handler = sysrq_handle_unrt,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800397 .help_msg = "nice-all-RT-tasks(N)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398 .action_msg = "Nice All RT Tasks",
399 .enable_mask = SYSRQ_ENABLE_RTNICE,
400};
401
402/* Key Operations table and lock */
403static DEFINE_SPINLOCK(sysrq_key_table_lock);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800404
405static struct sysrq_key_op *sysrq_key_table[36] = {
406 &sysrq_loglevel_op, /* 0 */
407 &sysrq_loglevel_op, /* 1 */
408 &sysrq_loglevel_op, /* 2 */
409 &sysrq_loglevel_op, /* 3 */
410 &sysrq_loglevel_op, /* 4 */
411 &sysrq_loglevel_op, /* 5 */
412 &sysrq_loglevel_op, /* 6 */
413 &sysrq_loglevel_op, /* 7 */
414 &sysrq_loglevel_op, /* 8 */
415 &sysrq_loglevel_op, /* 9 */
416
417 /*
Randy Dunlapd346cce2007-01-31 23:48:17 -0800418 * a: Don't use for system provided sysrqs, it is handled specially on
419 * sparc and will never arrive.
Andrew Mortonbf36b902006-03-25 03:07:08 -0800420 */
421 NULL, /* a */
422 &sysrq_reboot_op, /* b */
Hidetoshi Setocab8bd32009-07-29 15:04:14 -0700423 &sysrq_crash_op, /* c & ibm_emac driver debug */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800424 &sysrq_showlocks_op, /* d */
425 &sysrq_term_op, /* e */
426 &sysrq_moom_op, /* f */
Jason Wessel364b5b72009-05-13 21:56:59 -0500427 /* g: May be registered for the kernel debugger */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800428 NULL, /* g */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700429 NULL, /* h - reserved for help */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800430 &sysrq_kill_op, /* i */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700431#ifdef CONFIG_BLOCK
432 &sysrq_thaw_op, /* j */
433#else
Andrew Mortonbf36b902006-03-25 03:07:08 -0800434 NULL, /* j */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700435#endif
Andrew Mortonbf36b902006-03-25 03:07:08 -0800436 &sysrq_SAK_op, /* k */
Rik van Riel5045bca2008-04-29 00:59:21 -0700437#ifdef CONFIG_SMP
438 &sysrq_showallcpus_op, /* l */
439#else
Andrew Mortonbf36b902006-03-25 03:07:08 -0800440 NULL, /* l */
Rik van Riel5045bca2008-04-29 00:59:21 -0700441#endif
Andrew Mortonbf36b902006-03-25 03:07:08 -0800442 &sysrq_showmem_op, /* m */
443 &sysrq_unrt_op, /* n */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800444 /* o: This will often be registered as 'Off' at init time */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800445 NULL, /* o */
446 &sysrq_showregs_op, /* p */
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800447 &sysrq_show_timers_op, /* q */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800448 &sysrq_unraw_op, /* r */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800449 &sysrq_sync_op, /* s */
450 &sysrq_showstate_op, /* t */
451 &sysrq_mountro_op, /* u */
Jason Wessel364b5b72009-05-13 21:56:59 -0500452 /* v: May be registered for frame buffer console restore */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800453 NULL, /* v */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800454 &sysrq_showstate_blocked_op, /* w */
455 /* x: May be registered on ppc/powerpc for xmon */
David S. Miller916ca142012-10-16 09:34:01 -0700456 /* x: May be registered on sparc64 for global PMU dump */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800457 NULL, /* x */
David S. Miller93dae5b2008-05-19 23:46:00 -0700458 /* y: May be registered on sparc64 for global register dump */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800459 NULL, /* y */
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100460 &sysrq_ftrace_dump_op, /* z */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461};
462
463/* key2index calculation, -1 on invalid index */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800464static int sysrq_key_table_key2index(int key)
465{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466 int retval;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800467
468 if ((key >= '0') && (key <= '9'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469 retval = key - '0';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800470 else if ((key >= 'a') && (key <= 'z'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 retval = key + 10 - 'a';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800472 else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473 retval = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474 return retval;
475}
476
477/*
478 * get and put functions for the table, exposed to modules.
479 */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800480struct sysrq_key_op *__sysrq_get_key_op(int key)
481{
482 struct sysrq_key_op *op_p = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483 int i;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800484
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485 i = sysrq_key_table_key2index(key);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800486 if (i != -1)
487 op_p = sysrq_key_table[i];
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700488
Linus Torvalds1da177e2005-04-16 15:20:36 -0700489 return op_p;
490}
491
Andrew Mortonbf36b902006-03-25 03:07:08 -0800492static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
493{
494 int i = sysrq_key_table_key2index(key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700495
Linus Torvalds1da177e2005-04-16 15:20:36 -0700496 if (i != -1)
497 sysrq_key_table[i] = op_p;
498}
499
Dmitry Torokhovf3353972010-08-17 21:15:47 -0700500void __handle_sysrq(int key, bool check_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501{
502 struct sysrq_key_op *op_p;
503 int orig_log_level;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800504 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700505 unsigned long flags;
506
507 spin_lock_irqsave(&sysrq_key_table_lock, flags);
Andy Whitcroftfb144ad2009-01-15 13:50:52 -0800508 /*
509 * Raise the apparent loglevel to maximum so that the sysrq header
510 * is shown to provide the user with positive feedback. We do not
511 * simply emit this at KERN_EMERG as that would change message
512 * routing in the consumers of /proc/kmsg.
513 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514 orig_log_level = console_loglevel;
515 console_loglevel = 7;
516 printk(KERN_INFO "SysRq : ");
517
518 op_p = __sysrq_get_key_op(key);
519 if (op_p) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800520 /*
521 * Should we check for enabled operations (/proc/sysrq-trigger
522 * should not) and is the invoked operation enabled?
523 */
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800524 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800525 printk("%s\n", op_p->action_msg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526 console_loglevel = orig_log_level;
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700527 op_p->handler(key);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800528 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 printk("This sysrq operation is disabled.\n");
Andrew Mortonbf36b902006-03-25 03:07:08 -0800530 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531 } else {
532 printk("HELP : ");
533 /* Only print the help msg once per handler */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800534 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
535 if (sysrq_key_table[i]) {
536 int j;
537
538 for (j = 0; sysrq_key_table[i] !=
539 sysrq_key_table[j]; j++)
540 ;
541 if (j != i)
542 continue;
543 printk("%s ", sysrq_key_table[i]->help_msg);
544 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545 }
Andrew Mortonbf36b902006-03-25 03:07:08 -0800546 printk("\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547 console_loglevel = orig_log_level;
548 }
549 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
550}
551
Dmitry Torokhovf3353972010-08-17 21:15:47 -0700552void handle_sysrq(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553{
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800554 if (sysrq_on())
Dmitry Torokhovf3353972010-08-17 21:15:47 -0700555 __handle_sysrq(key, true);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800557EXPORT_SYMBOL(handle_sysrq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700559#ifdef CONFIG_INPUT
560
561/* Simple translation table for the SysRq keys */
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800562static const unsigned char sysrq_xlate[KEY_CNT] =
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700563 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */
564 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */
565 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */
566 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */
567 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */
568 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
569 "\r\000/"; /* 0x60 - 0x6f */
570
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800571struct sysrq_state {
572 struct input_handle handle;
573 struct work_struct reinject_work;
574 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
575 unsigned int alt;
576 unsigned int alt_use;
577 bool active;
578 bool need_reinject;
Dmitry Torokhov7ab7b5a2011-02-02 22:59:54 -0800579 bool reinjecting;
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800580};
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700581
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800582static void sysrq_reinject_alt_sysrq(struct work_struct *work)
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700583{
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800584 struct sysrq_state *sysrq =
585 container_of(work, struct sysrq_state, reinject_work);
586 struct input_handle *handle = &sysrq->handle;
587 unsigned int alt_code = sysrq->alt_use;
588
589 if (sysrq->need_reinject) {
Dmitry Torokhov7ab7b5a2011-02-02 22:59:54 -0800590 /* we do not want the assignment to be reordered */
591 sysrq->reinjecting = true;
592 mb();
593
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800594 /* Simulate press and release of Alt + SysRq */
595 input_inject_event(handle, EV_KEY, alt_code, 1);
596 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
597 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
598
599 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
600 input_inject_event(handle, EV_KEY, alt_code, 0);
601 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
Dmitry Torokhov7ab7b5a2011-02-02 22:59:54 -0800602
603 mb();
604 sysrq->reinjecting = false;
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800605 }
606}
607
608static bool sysrq_filter(struct input_handle *handle,
609 unsigned int type, unsigned int code, int value)
610{
611 struct sysrq_state *sysrq = handle->private;
612 bool was_active = sysrq->active;
Dmitry Torokhov1966cb22010-09-29 18:04:21 -0700613 bool suppress;
614
Dmitry Torokhov7ab7b5a2011-02-02 22:59:54 -0800615 /*
616 * Do not filter anything if we are in the process of re-injecting
617 * Alt+SysRq combination.
618 */
619 if (sysrq->reinjecting)
620 return false;
621
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800622 switch (type) {
Dmitry Torokhov1966cb22010-09-29 18:04:21 -0700623
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800624 case EV_SYN:
625 suppress = false;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700626 break;
627
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800628 case EV_KEY:
629 switch (code) {
630
631 case KEY_LEFTALT:
632 case KEY_RIGHTALT:
633 if (!value) {
634 /* One of ALTs is being released */
635 if (sysrq->active && code == sysrq->alt_use)
636 sysrq->active = false;
637
638 sysrq->alt = KEY_RESERVED;
639
640 } else if (value != 2) {
641 sysrq->alt = code;
642 sysrq->need_reinject = false;
643 }
644 break;
645
646 case KEY_SYSRQ:
647 if (value == 1 && sysrq->alt != KEY_RESERVED) {
648 sysrq->active = true;
649 sysrq->alt_use = sysrq->alt;
650 /*
651 * If nothing else will be pressed we'll need
Dmitry Torokhov7ab7b5a2011-02-02 22:59:54 -0800652 * to re-inject Alt-SysRq keysroke.
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800653 */
654 sysrq->need_reinject = true;
655 }
656
657 /*
658 * Pretend that sysrq was never pressed at all. This
659 * is needed to properly handle KGDB which will try
660 * to release all keys after exiting debugger. If we
661 * do not clear key bit it KGDB will end up sending
662 * release events for Alt and SysRq, potentially
663 * triggering print screen function.
664 */
665 if (sysrq->active)
666 clear_bit(KEY_SYSRQ, handle->dev->key);
667
668 break;
669
670 default:
671 if (sysrq->active && value && value != 2) {
672 sysrq->need_reinject = false;
673 __handle_sysrq(sysrq_xlate[code], true);
674 }
675 break;
676 }
677
678 suppress = sysrq->active;
679
680 if (!sysrq->active) {
681 /*
682 * If we are not suppressing key presses keep track of
683 * keyboard state so we can release keys that have been
684 * pressed before entering SysRq mode.
685 */
686 if (value)
687 set_bit(code, sysrq->key_down);
688 else
689 clear_bit(code, sysrq->key_down);
690
691 if (was_active)
692 schedule_work(&sysrq->reinject_work);
693
694 } else if (value == 0 &&
695 test_and_clear_bit(code, sysrq->key_down)) {
696 /*
697 * Pass on release events for keys that was pressed before
698 * entering SysRq mode.
699 */
700 suppress = false;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700701 }
702 break;
703
704 default:
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800705 suppress = sysrq->active;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700706 break;
707 }
708
Dmitry Torokhov1966cb22010-09-29 18:04:21 -0700709 return suppress;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700710}
711
712static int sysrq_connect(struct input_handler *handler,
713 struct input_dev *dev,
714 const struct input_device_id *id)
715{
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800716 struct sysrq_state *sysrq;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700717 int error;
718
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800719 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);
720 if (!sysrq)
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700721 return -ENOMEM;
722
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800723 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700724
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800725 sysrq->handle.dev = dev;
726 sysrq->handle.handler = handler;
727 sysrq->handle.name = "sysrq";
728 sysrq->handle.private = sysrq;
729
730 error = input_register_handle(&sysrq->handle);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700731 if (error) {
732 pr_err("Failed to register input sysrq handler, error %d\n",
733 error);
734 goto err_free;
735 }
736
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800737 error = input_open_device(&sysrq->handle);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700738 if (error) {
739 pr_err("Failed to open input device, error %d\n", error);
740 goto err_unregister;
741 }
742
743 return 0;
744
745 err_unregister:
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800746 input_unregister_handle(&sysrq->handle);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700747 err_free:
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800748 kfree(sysrq);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700749 return error;
750}
751
752static void sysrq_disconnect(struct input_handle *handle)
753{
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800754 struct sysrq_state *sysrq = handle->private;
755
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700756 input_close_device(handle);
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800757 cancel_work_sync(&sysrq->reinject_work);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700758 input_unregister_handle(handle);
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800759 kfree(sysrq);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700760}
761
762/*
Dmitry Torokhov1966cb22010-09-29 18:04:21 -0700763 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all
764 * keyboards have SysRq key predefined and so user may add it to keymap
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700765 * later, but we expect all such keyboards to have left alt.
766 */
767static const struct input_device_id sysrq_ids[] = {
768 {
769 .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
770 INPUT_DEVICE_ID_MATCH_KEYBIT,
771 .evbit = { BIT_MASK(EV_KEY) },
772 .keybit = { BIT_MASK(KEY_LEFTALT) },
773 },
774 { },
775};
776
777static struct input_handler sysrq_handler = {
778 .filter = sysrq_filter,
779 .connect = sysrq_connect,
780 .disconnect = sysrq_disconnect,
781 .name = "sysrq",
782 .id_table = sysrq_ids,
783};
784
785static bool sysrq_handler_registered;
786
787static inline void sysrq_register_handler(void)
788{
789 int error;
790
791 error = input_register_handler(&sysrq_handler);
792 if (error)
793 pr_err("Failed to register input handler, error %d", error);
794 else
795 sysrq_handler_registered = true;
796}
797
798static inline void sysrq_unregister_handler(void)
799{
800 if (sysrq_handler_registered) {
801 input_unregister_handler(&sysrq_handler);
802 sysrq_handler_registered = false;
803 }
804}
805
806#else
807
808static inline void sysrq_register_handler(void)
809{
810}
811
812static inline void sysrq_unregister_handler(void)
813{
814}
815
816#endif /* CONFIG_INPUT */
817
818int sysrq_toggle_support(int enable_mask)
819{
820 bool was_enabled = sysrq_on();
821
822 sysrq_enabled = enable_mask;
823
824 if (was_enabled != sysrq_on()) {
825 if (sysrq_on())
826 sysrq_register_handler();
827 else
828 sysrq_unregister_handler();
829 }
830
831 return 0;
832}
833
Adrian Bunkcf62ddc2005-11-08 21:39:47 -0800834static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
Andrew Mortonbf36b902006-03-25 03:07:08 -0800835 struct sysrq_key_op *remove_op_p)
836{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700837 int retval;
838 unsigned long flags;
839
840 spin_lock_irqsave(&sysrq_key_table_lock, flags);
841 if (__sysrq_get_key_op(key) == remove_op_p) {
842 __sysrq_put_key_op(key, insert_op_p);
843 retval = 0;
844 } else {
845 retval = -1;
846 }
847 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700848 return retval;
849}
850
851int register_sysrq_key(int key, struct sysrq_key_op *op_p)
852{
853 return __sysrq_swap_key_ops(key, op_p, NULL);
854}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800855EXPORT_SYMBOL(register_sysrq_key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700856
857int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
858{
859 return __sysrq_swap_key_ops(key, NULL, op_p);
860}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700861EXPORT_SYMBOL(unregister_sysrq_key);
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700862
863#ifdef CONFIG_PROC_FS
864/*
865 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
866 */
867static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
868 size_t count, loff_t *ppos)
869{
870 if (count) {
871 char c;
872
873 if (get_user(c, buf))
874 return -EFAULT;
Dmitry Torokhovf3353972010-08-17 21:15:47 -0700875 __handle_sysrq(c, false);
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700876 }
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700877
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700878 return count;
879}
880
881static const struct file_operations proc_sysrq_trigger_operations = {
882 .write = write_sysrq_trigger,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200883 .llseek = noop_llseek,
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700884};
885
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700886static void sysrq_init_procfs(void)
887{
888 if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
889 &proc_sysrq_trigger_operations))
890 pr_err("Failed to register proc interface\n");
891}
892
893#else
894
895static inline void sysrq_init_procfs(void)
896{
897}
898
899#endif /* CONFIG_PROC_FS */
900
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700901static int __init sysrq_init(void)
902{
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700903 sysrq_init_procfs();
904
905 if (sysrq_on())
906 sysrq_register_handler();
907
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700908 return 0;
909}
910module_init(sysrq_init);