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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>
35#include <linux/buffer_head.h> /* for fsync_bdev() */
36#include <linux/swap.h>
37#include <linux/spinlock.h>
38#include <linux/vt_kern.h>
39#include <linux/workqueue.h>
Ingo Molnar88ad0bf62007-02-16 01:28:16 -080040#include <linux/hrtimer.h>
David Rientjes5a3135c22007-10-16 23:25:53 -070041#include <linux/oom.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090042#include <linux/slab.h>
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070043#include <linux/input.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 */
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070049static int __read_mostly sysrq_enabled = 1;
50static 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{
309 show_mem();
310}
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 */
557static const unsigned char sysrq_xlate[KEY_MAX + 1] =
558 "\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
566static bool sysrq_down;
567static int sysrq_alt_use;
568static int sysrq_alt;
569
570static bool sysrq_filter(struct input_handle *handle, unsigned int type,
571 unsigned int code, int value)
572{
573 if (type != EV_KEY)
574 goto out;
575
576 switch (code) {
577
578 case KEY_LEFTALT:
579 case KEY_RIGHTALT:
580 if (value)
581 sysrq_alt = code;
Dmitry Torokhovf5dec512010-06-09 08:13:06 -0700582 else {
583 if (sysrq_down && code == sysrq_alt_use)
584 sysrq_down = false;
585
586 sysrq_alt = 0;
587 }
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700588 break;
589
590 case KEY_SYSRQ:
591 if (value == 1 && sysrq_alt) {
592 sysrq_down = true;
593 sysrq_alt_use = sysrq_alt;
594 }
595 break;
596
597 default:
598 if (sysrq_down && value && value != 2)
Dmitry Torokhovf3353972010-08-17 21:15:47 -0700599 __handle_sysrq(sysrq_xlate[code], true);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700600 break;
601 }
602
603out:
604 return sysrq_down;
605}
606
607static int sysrq_connect(struct input_handler *handler,
608 struct input_dev *dev,
609 const struct input_device_id *id)
610{
611 struct input_handle *handle;
612 int error;
613
614 sysrq_down = false;
615 sysrq_alt = 0;
616
617 handle = kzalloc(sizeof(struct input_handle), GFP_KERNEL);
618 if (!handle)
619 return -ENOMEM;
620
621 handle->dev = dev;
622 handle->handler = handler;
623 handle->name = "sysrq";
624
625 error = input_register_handle(handle);
626 if (error) {
627 pr_err("Failed to register input sysrq handler, error %d\n",
628 error);
629 goto err_free;
630 }
631
632 error = input_open_device(handle);
633 if (error) {
634 pr_err("Failed to open input device, error %d\n", error);
635 goto err_unregister;
636 }
637
638 return 0;
639
640 err_unregister:
641 input_unregister_handle(handle);
642 err_free:
643 kfree(handle);
644 return error;
645}
646
647static void sysrq_disconnect(struct input_handle *handle)
648{
649 input_close_device(handle);
650 input_unregister_handle(handle);
651 kfree(handle);
652}
653
654/*
655 * We are matching on KEY_LEFTALT insteard of KEY_SYSRQ because not all
656 * keyboards have SysRq ikey predefined and so user may add it to keymap
657 * later, but we expect all such keyboards to have left alt.
658 */
659static const struct input_device_id sysrq_ids[] = {
660 {
661 .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
662 INPUT_DEVICE_ID_MATCH_KEYBIT,
663 .evbit = { BIT_MASK(EV_KEY) },
664 .keybit = { BIT_MASK(KEY_LEFTALT) },
665 },
666 { },
667};
668
669static struct input_handler sysrq_handler = {
670 .filter = sysrq_filter,
671 .connect = sysrq_connect,
672 .disconnect = sysrq_disconnect,
673 .name = "sysrq",
674 .id_table = sysrq_ids,
675};
676
677static bool sysrq_handler_registered;
678
679static inline void sysrq_register_handler(void)
680{
681 int error;
682
683 error = input_register_handler(&sysrq_handler);
684 if (error)
685 pr_err("Failed to register input handler, error %d", error);
686 else
687 sysrq_handler_registered = true;
688}
689
690static inline void sysrq_unregister_handler(void)
691{
692 if (sysrq_handler_registered) {
693 input_unregister_handler(&sysrq_handler);
694 sysrq_handler_registered = false;
695 }
696}
697
698#else
699
700static inline void sysrq_register_handler(void)
701{
702}
703
704static inline void sysrq_unregister_handler(void)
705{
706}
707
708#endif /* CONFIG_INPUT */
709
710int sysrq_toggle_support(int enable_mask)
711{
712 bool was_enabled = sysrq_on();
713
714 sysrq_enabled = enable_mask;
715
716 if (was_enabled != sysrq_on()) {
717 if (sysrq_on())
718 sysrq_register_handler();
719 else
720 sysrq_unregister_handler();
721 }
722
723 return 0;
724}
725
Adrian Bunkcf62ddc2005-11-08 21:39:47 -0800726static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
Andrew Mortonbf36b902006-03-25 03:07:08 -0800727 struct sysrq_key_op *remove_op_p)
728{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729 int retval;
730 unsigned long flags;
731
732 spin_lock_irqsave(&sysrq_key_table_lock, flags);
733 if (__sysrq_get_key_op(key) == remove_op_p) {
734 __sysrq_put_key_op(key, insert_op_p);
735 retval = 0;
736 } else {
737 retval = -1;
738 }
739 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 return retval;
741}
742
743int register_sysrq_key(int key, struct sysrq_key_op *op_p)
744{
745 return __sysrq_swap_key_ops(key, op_p, NULL);
746}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800747EXPORT_SYMBOL(register_sysrq_key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748
749int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
750{
751 return __sysrq_swap_key_ops(key, NULL, op_p);
752}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753EXPORT_SYMBOL(unregister_sysrq_key);
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700754
755#ifdef CONFIG_PROC_FS
756/*
757 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
758 */
759static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
760 size_t count, loff_t *ppos)
761{
762 if (count) {
763 char c;
764
765 if (get_user(c, buf))
766 return -EFAULT;
Dmitry Torokhovf3353972010-08-17 21:15:47 -0700767 __handle_sysrq(c, false);
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700768 }
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700769
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700770 return count;
771}
772
773static const struct file_operations proc_sysrq_trigger_operations = {
774 .write = write_sysrq_trigger,
775};
776
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700777static void sysrq_init_procfs(void)
778{
779 if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
780 &proc_sysrq_trigger_operations))
781 pr_err("Failed to register proc interface\n");
782}
783
784#else
785
786static inline void sysrq_init_procfs(void)
787{
788}
789
790#endif /* CONFIG_PROC_FS */
791
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700792static int __init sysrq_init(void)
793{
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700794 sysrq_init_procfs();
795
796 if (sysrq_on())
797 sysrq_register_handler();
798
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -0700799 return 0;
800}
801module_init(sysrq_init);