blob: 05728894a88c23330e7b57eb8994f50477fc1b73 [file] [log] [blame]
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 Rientjes5a3135c2007-10-16 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 Viroff01bb42011-09-16 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 Rientjes08ab9b12012-03-21 16:34:04 -0700349 out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0, NULL, true);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350}
351
David Howells65f27f32006-11-22 14:55:48 +0000352static DECLARE_WORK(moom_work, moom_callback);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700354static void sysrq_handle_moom(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700355{
356 schedule_work(&moom_work);
357}
358static struct sysrq_key_op sysrq_moom_op = {
359 .handler = sysrq_handle_moom,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800360 .help_msg = "memory-full-oom-kill(F)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 .action_msg = "Manual OOM execution",
Naohiro Ooiwab4236f82008-10-15 22:01:43 -0700362 .enable_mask = SYSRQ_ENABLE_SIGNAL,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363};
364
Eric Sandeenc2d75432009-03-31 15:23:46 -0700365#ifdef CONFIG_BLOCK
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700366static void sysrq_handle_thaw(int key)
Eric Sandeenc2d75432009-03-31 15:23:46 -0700367{
368 emergency_thaw_all();
369}
370static struct sysrq_key_op sysrq_thaw_op = {
371 .handler = sysrq_handle_thaw,
372 .help_msg = "thaw-filesystems(J)",
373 .action_msg = "Emergency Thaw of all frozen filesystems",
374 .enable_mask = SYSRQ_ENABLE_SIGNAL,
375};
376#endif
377
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700378static void sysrq_handle_kill(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379{
380 send_sig_all(SIGKILL);
381 console_loglevel = 8;
382}
383static struct sysrq_key_op sysrq_kill_op = {
384 .handler = sysrq_handle_kill,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800385 .help_msg = "kill-all-tasks(I)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386 .action_msg = "Kill All Tasks",
387 .enable_mask = SYSRQ_ENABLE_SIGNAL,
388};
389
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700390static void sysrq_handle_unrt(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391{
392 normalize_rt_tasks();
393}
394static struct sysrq_key_op sysrq_unrt_op = {
395 .handler = sysrq_handle_unrt,
Randy Dunlap208b95c2009-01-06 14:41:13 -0800396 .help_msg = "nice-all-RT-tasks(N)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397 .action_msg = "Nice All RT Tasks",
398 .enable_mask = SYSRQ_ENABLE_RTNICE,
399};
400
401/* Key Operations table and lock */
402static DEFINE_SPINLOCK(sysrq_key_table_lock);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800403
404static struct sysrq_key_op *sysrq_key_table[36] = {
405 &sysrq_loglevel_op, /* 0 */
406 &sysrq_loglevel_op, /* 1 */
407 &sysrq_loglevel_op, /* 2 */
408 &sysrq_loglevel_op, /* 3 */
409 &sysrq_loglevel_op, /* 4 */
410 &sysrq_loglevel_op, /* 5 */
411 &sysrq_loglevel_op, /* 6 */
412 &sysrq_loglevel_op, /* 7 */
413 &sysrq_loglevel_op, /* 8 */
414 &sysrq_loglevel_op, /* 9 */
415
416 /*
Randy Dunlapd346cce2007-01-31 23:48:17 -0800417 * a: Don't use for system provided sysrqs, it is handled specially on
418 * sparc and will never arrive.
Andrew Mortonbf36b902006-03-25 03:07:08 -0800419 */
420 NULL, /* a */
421 &sysrq_reboot_op, /* b */
Hidetoshi Setocab8bd32009-07-29 15:04:14 -0700422 &sysrq_crash_op, /* c & ibm_emac driver debug */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800423 &sysrq_showlocks_op, /* d */
424 &sysrq_term_op, /* e */
425 &sysrq_moom_op, /* f */
Jason Wessel364b5b72009-05-13 21:56:59 -0500426 /* g: May be registered for the kernel debugger */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800427 NULL, /* g */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700428 NULL, /* h - reserved for help */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800429 &sysrq_kill_op, /* i */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700430#ifdef CONFIG_BLOCK
431 &sysrq_thaw_op, /* j */
432#else
Andrew Mortonbf36b902006-03-25 03:07:08 -0800433 NULL, /* j */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700434#endif
Andrew Mortonbf36b902006-03-25 03:07:08 -0800435 &sysrq_SAK_op, /* k */
Rik van Riel5045bca2008-04-29 00:59:21 -0700436#ifdef CONFIG_SMP
437 &sysrq_showallcpus_op, /* l */
438#else
Andrew Mortonbf36b902006-03-25 03:07:08 -0800439 NULL, /* l */
Rik van Riel5045bca2008-04-29 00:59:21 -0700440#endif
Andrew Mortonbf36b902006-03-25 03:07:08 -0800441 &sysrq_showmem_op, /* m */
442 &sysrq_unrt_op, /* n */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800443 /* o: This will often be registered as 'Off' at init time */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800444 NULL, /* o */
445 &sysrq_showregs_op, /* p */
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800446 &sysrq_show_timers_op, /* q */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800447 &sysrq_unraw_op, /* r */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800448 &sysrq_sync_op, /* s */
449 &sysrq_showstate_op, /* t */
450 &sysrq_mountro_op, /* u */
Jason Wessel364b5b72009-05-13 21:56:59 -0500451 /* v: May be registered for frame buffer console restore */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800452 NULL, /* v */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800453 &sysrq_showstate_blocked_op, /* w */
454 /* x: May be registered on ppc/powerpc for xmon */
455 NULL, /* x */
David S. Miller93dae5b2008-05-19 23:46:00 -0700456 /* y: May be registered on sparc64 for global register dump */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800457 NULL, /* y */
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100458 &sysrq_ftrace_dump_op, /* z */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459};
460
461/* key2index calculation, -1 on invalid index */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800462static int sysrq_key_table_key2index(int key)
463{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464 int retval;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800465
466 if ((key >= '0') && (key <= '9'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467 retval = key - '0';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800468 else if ((key >= 'a') && (key <= 'z'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469 retval = key + 10 - 'a';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800470 else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 retval = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472 return retval;
473}
474
475/*
476 * get and put functions for the table, exposed to modules.
477 */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800478struct sysrq_key_op *__sysrq_get_key_op(int key)
479{
480 struct sysrq_key_op *op_p = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481 int i;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800482
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483 i = sysrq_key_table_key2index(key);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800484 if (i != -1)
485 op_p = sysrq_key_table[i];
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700486
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487 return op_p;
488}
489
Andrew Mortonbf36b902006-03-25 03:07:08 -0800490static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
491{
492 int i = sysrq_key_table_key2index(key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494 if (i != -1)
495 sysrq_key_table[i] = op_p;
496}
497
Dmitry Torokhovf3353972010-08-17 21:15:47 -0700498void __handle_sysrq(int key, bool check_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700499{
500 struct sysrq_key_op *op_p;
501 int orig_log_level;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800502 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503 unsigned long flags;
504
505 spin_lock_irqsave(&sysrq_key_table_lock, flags);
Andy Whitcroftfb144ad2009-01-15 13:50:52 -0800506 /*
507 * Raise the apparent loglevel to maximum so that the sysrq header
508 * is shown to provide the user with positive feedback. We do not
509 * simply emit this at KERN_EMERG as that would change message
510 * routing in the consumers of /proc/kmsg.
511 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512 orig_log_level = console_loglevel;
513 console_loglevel = 7;
514 printk(KERN_INFO "SysRq : ");
515
516 op_p = __sysrq_get_key_op(key);
517 if (op_p) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800518 /*
519 * Should we check for enabled operations (/proc/sysrq-trigger
520 * should not) and is the invoked operation enabled?
521 */
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800522 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800523 printk("%s\n", op_p->action_msg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524 console_loglevel = orig_log_level;
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700525 op_p->handler(key);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800526 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527 printk("This sysrq operation is disabled.\n");
Andrew Mortonbf36b902006-03-25 03:07:08 -0800528 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 } else {
530 printk("HELP : ");
531 /* Only print the help msg once per handler */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800532 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
533 if (sysrq_key_table[i]) {
534 int j;
535
536 for (j = 0; sysrq_key_table[i] !=
537 sysrq_key_table[j]; j++)
538 ;
539 if (j != i)
540 continue;
541 printk("%s ", sysrq_key_table[i]->help_msg);
542 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543 }
Andrew Mortonbf36b902006-03-25 03:07:08 -0800544 printk("\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545 console_loglevel = orig_log_level;
546 }
547 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
548}
549
Dmitry Torokhovf3353972010-08-17 21:15:47 -0700550void handle_sysrq(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551{
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800552 if (sysrq_on())
Dmitry Torokhovf3353972010-08-17 21:15:47 -0700553 __handle_sysrq(key, true);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800555EXPORT_SYMBOL(handle_sysrq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700557#ifdef CONFIG_INPUT
558
559/* Simple translation table for the SysRq keys */
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800560static const unsigned char sysrq_xlate[KEY_CNT] =
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700561 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */
562 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */
563 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */
564 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */
565 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */
566 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
567 "\r\000/"; /* 0x60 - 0x6f */
568
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800569struct sysrq_state {
570 struct input_handle handle;
571 struct work_struct reinject_work;
572 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
573 unsigned int alt;
574 unsigned int alt_use;
575 bool active;
576 bool need_reinject;
Dmitry Torokhov7ab7b5a2011-02-02 22:59:54 -0800577 bool reinjecting;
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800578};
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700579
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800580static void sysrq_reinject_alt_sysrq(struct work_struct *work)
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700581{
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800582 struct sysrq_state *sysrq =
583 container_of(work, struct sysrq_state, reinject_work);
584 struct input_handle *handle = &sysrq->handle;
585 unsigned int alt_code = sysrq->alt_use;
586
587 if (sysrq->need_reinject) {
Dmitry Torokhov7ab7b5a2011-02-02 22:59:54 -0800588 /* we do not want the assignment to be reordered */
589 sysrq->reinjecting = true;
590 mb();
591
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800592 /* Simulate press and release of Alt + SysRq */
593 input_inject_event(handle, EV_KEY, alt_code, 1);
594 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
595 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
596
597 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
598 input_inject_event(handle, EV_KEY, alt_code, 0);
599 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
Dmitry Torokhov7ab7b5a2011-02-02 22:59:54 -0800600
601 mb();
602 sysrq->reinjecting = false;
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800603 }
604}
605
606static bool sysrq_filter(struct input_handle *handle,
607 unsigned int type, unsigned int code, int value)
608{
609 struct sysrq_state *sysrq = handle->private;
610 bool was_active = sysrq->active;
Dmitry Torokhov1966cb22010-09-29 18:04:21 -0700611 bool suppress;
612
Dmitry Torokhov7ab7b5a2011-02-02 22:59:54 -0800613 /*
614 * Do not filter anything if we are in the process of re-injecting
615 * Alt+SysRq combination.
616 */
617 if (sysrq->reinjecting)
618 return false;
619
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800620 switch (type) {
Dmitry Torokhov1966cb22010-09-29 18:04:21 -0700621
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800622 case EV_SYN:
623 suppress = false;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700624 break;
625
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800626 case EV_KEY:
627 switch (code) {
628
629 case KEY_LEFTALT:
630 case KEY_RIGHTALT:
631 if (!value) {
632 /* One of ALTs is being released */
633 if (sysrq->active && code == sysrq->alt_use)
634 sysrq->active = false;
635
636 sysrq->alt = KEY_RESERVED;
637
638 } else if (value != 2) {
639 sysrq->alt = code;
640 sysrq->need_reinject = false;
641 }
642 break;
643
644 case KEY_SYSRQ:
645 if (value == 1 && sysrq->alt != KEY_RESERVED) {
646 sysrq->active = true;
647 sysrq->alt_use = sysrq->alt;
648 /*
649 * If nothing else will be pressed we'll need
Dmitry Torokhov7ab7b5a2011-02-02 22:59:54 -0800650 * to re-inject Alt-SysRq keysroke.
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800651 */
652 sysrq->need_reinject = true;
653 }
654
655 /*
656 * Pretend that sysrq was never pressed at all. This
657 * is needed to properly handle KGDB which will try
658 * to release all keys after exiting debugger. If we
659 * do not clear key bit it KGDB will end up sending
660 * release events for Alt and SysRq, potentially
661 * triggering print screen function.
662 */
663 if (sysrq->active)
664 clear_bit(KEY_SYSRQ, handle->dev->key);
665
666 break;
667
668 default:
669 if (sysrq->active && value && value != 2) {
670 sysrq->need_reinject = false;
671 __handle_sysrq(sysrq_xlate[code], true);
672 }
673 break;
674 }
675
676 suppress = sysrq->active;
677
678 if (!sysrq->active) {
679 /*
680 * If we are not suppressing key presses keep track of
681 * keyboard state so we can release keys that have been
682 * pressed before entering SysRq mode.
683 */
684 if (value)
685 set_bit(code, sysrq->key_down);
686 else
687 clear_bit(code, sysrq->key_down);
688
689 if (was_active)
690 schedule_work(&sysrq->reinject_work);
691
692 } else if (value == 0 &&
693 test_and_clear_bit(code, sysrq->key_down)) {
694 /*
695 * Pass on release events for keys that was pressed before
696 * entering SysRq mode.
697 */
698 suppress = false;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700699 }
700 break;
701
702 default:
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800703 suppress = sysrq->active;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700704 break;
705 }
706
Dmitry Torokhov1966cb22010-09-29 18:04:21 -0700707 return suppress;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700708}
709
710static int sysrq_connect(struct input_handler *handler,
711 struct input_dev *dev,
712 const struct input_device_id *id)
713{
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800714 struct sysrq_state *sysrq;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700715 int error;
716
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800717 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);
718 if (!sysrq)
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700719 return -ENOMEM;
720
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800721 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700722
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800723 sysrq->handle.dev = dev;
724 sysrq->handle.handler = handler;
725 sysrq->handle.name = "sysrq";
726 sysrq->handle.private = sysrq;
727
728 error = input_register_handle(&sysrq->handle);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700729 if (error) {
730 pr_err("Failed to register input sysrq handler, error %d\n",
731 error);
732 goto err_free;
733 }
734
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800735 error = input_open_device(&sysrq->handle);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700736 if (error) {
737 pr_err("Failed to open input device, error %d\n", error);
738 goto err_unregister;
739 }
740
741 return 0;
742
743 err_unregister:
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800744 input_unregister_handle(&sysrq->handle);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700745 err_free:
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800746 kfree(sysrq);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700747 return error;
748}
749
750static void sysrq_disconnect(struct input_handle *handle)
751{
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800752 struct sysrq_state *sysrq = handle->private;
753
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700754 input_close_device(handle);
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800755 cancel_work_sync(&sysrq->reinject_work);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700756 input_unregister_handle(handle);
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800757 kfree(sysrq);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700758}
759
760/*
Dmitry Torokhov1966cb22010-09-29 18:04:21 -0700761 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all
762 * keyboards have SysRq key predefined and so user may add it to keymap
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700763 * later, but we expect all such keyboards to have left alt.
764 */
765static const struct input_device_id sysrq_ids[] = {
766 {
767 .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
768 INPUT_DEVICE_ID_MATCH_KEYBIT,
769 .evbit = { BIT_MASK(EV_KEY) },
770 .keybit = { BIT_MASK(KEY_LEFTALT) },
771 },
772 { },
773};
774
775static struct input_handler sysrq_handler = {
776 .filter = sysrq_filter,
777 .connect = sysrq_connect,
778 .disconnect = sysrq_disconnect,
779 .name = "sysrq",
780 .id_table = sysrq_ids,
781};
782
783static bool sysrq_handler_registered;
784
785static inline void sysrq_register_handler(void)
786{
787 int error;
788
789 error = input_register_handler(&sysrq_handler);
790 if (error)
791 pr_err("Failed to register input handler, error %d", error);
792 else
793 sysrq_handler_registered = true;
794}
795
796static inline void sysrq_unregister_handler(void)
797{
798 if (sysrq_handler_registered) {
799 input_unregister_handler(&sysrq_handler);
800 sysrq_handler_registered = false;
801 }
802}
803
804#else
805
806static inline void sysrq_register_handler(void)
807{
808}
809
810static inline void sysrq_unregister_handler(void)
811{
812}
813
814#endif /* CONFIG_INPUT */
815
816int sysrq_toggle_support(int enable_mask)
817{
818 bool was_enabled = sysrq_on();
819
820 sysrq_enabled = enable_mask;
821
822 if (was_enabled != sysrq_on()) {
823 if (sysrq_on())
824 sysrq_register_handler();
825 else
826 sysrq_unregister_handler();
827 }
828
829 return 0;
830}
831
Adrian Bunkcf62ddc2005-11-08 21:39:47 -0800832static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
Andrew Mortonbf36b902006-03-25 03:07:08 -0800833 struct sysrq_key_op *remove_op_p)
834{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700835 int retval;
836 unsigned long flags;
837
838 spin_lock_irqsave(&sysrq_key_table_lock, flags);
839 if (__sysrq_get_key_op(key) == remove_op_p) {
840 __sysrq_put_key_op(key, insert_op_p);
841 retval = 0;
842 } else {
843 retval = -1;
844 }
845 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700846 return retval;
847}
848
849int register_sysrq_key(int key, struct sysrq_key_op *op_p)
850{
851 return __sysrq_swap_key_ops(key, op_p, NULL);
852}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800853EXPORT_SYMBOL(register_sysrq_key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700854
855int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
856{
857 return __sysrq_swap_key_ops(key, NULL, op_p);
858}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700859EXPORT_SYMBOL(unregister_sysrq_key);
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700860
861#ifdef CONFIG_PROC_FS
862/*
863 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
864 */
865static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
866 size_t count, loff_t *ppos)
867{
868 if (count) {
869 char c;
870
871 if (get_user(c, buf))
872 return -EFAULT;
Dmitry Torokhovf3353972010-08-17 21:15:47 -0700873 __handle_sysrq(c, false);
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700874 }
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700875
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700876 return count;
877}
878
879static const struct file_operations proc_sysrq_trigger_operations = {
880 .write = write_sysrq_trigger,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200881 .llseek = noop_llseek,
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700882};
883
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700884static void sysrq_init_procfs(void)
885{
886 if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
887 &proc_sysrq_trigger_operations))
888 pr_err("Failed to register proc interface\n");
889}
890
891#else
892
893static inline void sysrq_init_procfs(void)
894{
895}
896
897#endif /* CONFIG_PROC_FS */
898
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700899static int __init sysrq_init(void)
900{
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700901 sysrq_init_procfs();
902
903 if (sysrq_on())
904 sysrq_register_handler();
905
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700906 return 0;
907}
908module_init(sysrq_init);