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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
Ingo Molnar3f07c012017-02-08 18:51:30 +010017#include <linux/sched/signal.h>
Clark Williams8bd75c72013-02-07 09:47:07 -060018#include <linux/sched/rt.h>
Ingo Molnarb17b0152017-02-08 18:51:35 +010019#include <linux/sched/debug.h>
Ingo Molnar29930022017-02-08 18:51:36 +010020#include <linux/sched/task.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <linux/interrupt.h>
22#include <linux/mm.h>
23#include <linux/fs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#include <linux/mount.h>
25#include <linux/kdev_t.h>
26#include <linux/major.h>
27#include <linux/reboot.h>
28#include <linux/sysrq.h>
29#include <linux/kbd_kern.h>
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -070030#include <linux/proc_fs.h>
Ingo Molnarc1dc0b92009-08-02 11:28:21 +020031#include <linux/nmi.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070032#include <linux/quotaops.h>
Ingo Molnarcdd6c482009-09-21 12:02:48 +020033#include <linux/perf_event.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070034#include <linux/kernel.h>
35#include <linux/module.h>
36#include <linux/suspend.h>
37#include <linux/writeback.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070038#include <linux/swap.h>
39#include <linux/spinlock.h>
40#include <linux/vt_kern.h>
41#include <linux/workqueue.h>
Ingo Molnar88ad0bf62007-02-16 01:28:16 -080042#include <linux/hrtimer.h>
David Rientjes5a3135c22007-10-16 23:25:53 -070043#include <linux/oom.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090044#include <linux/slab.h>
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070045#include <linux/input.h>
Al Viroff01bb42011-09-16 02:31:11 -040046#include <linux/uaccess.h>
Mathieu Poirier154b7a42013-01-06 23:23:33 -080047#include <linux/moduleparam.h>
Mathieu J. Poirier39030782013-04-01 22:14:19 -070048#include <linux/jiffies.h>
Mathieu J. Poirier3d289512013-06-05 22:51:46 -070049#include <linux/syscalls.h>
Mathieu J. Poirier4c076eb2013-08-03 17:22:08 -070050#include <linux/of.h>
Rik van Riel722773a2014-06-06 14:38:14 -070051#include <linux/rcupdate.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070052
53#include <asm/ptrace.h>
Heiko Carstens2033b0c2006-10-06 16:38:42 +020054#include <asm/irq_regs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070055
56/* Whether we react on sysrq keys or just ignore them */
Ben Hutchings8eaede42013-10-07 01:05:46 +010057static int __read_mostly sysrq_enabled = CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070058static bool __read_mostly sysrq_always_enabled;
Ingo Molnar5d6f6472006-12-13 00:34:36 -080059
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070060static bool sysrq_on(void)
Ingo Molnar5d6f6472006-12-13 00:34:36 -080061{
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070062 return sysrq_enabled || sysrq_always_enabled;
Ingo Molnar5d6f6472006-12-13 00:34:36 -080063}
64
65/*
66 * A value of 1 means 'all', other nonzero values are an op mask:
67 */
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070068static bool sysrq_on_mask(int mask)
Ingo Molnar5d6f6472006-12-13 00:34:36 -080069{
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070070 return sysrq_always_enabled ||
71 sysrq_enabled == 1 ||
72 (sysrq_enabled & mask);
Ingo Molnar5d6f6472006-12-13 00:34:36 -080073}
74
75static int __init sysrq_always_enabled_setup(char *str)
76{
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070077 sysrq_always_enabled = true;
78 pr_info("sysrq always enabled.\n");
Ingo Molnar5d6f6472006-12-13 00:34:36 -080079
80 return 1;
81}
82
83__setup("sysrq_always_enabled", sysrq_always_enabled_setup);
84
Linus Torvalds1da177e2005-04-16 15:20:36 -070085
Dmitry Torokhov1495cc92010-08-17 21:15:46 -070086static void sysrq_handle_loglevel(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -070087{
88 int i;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -070089
Linus Torvalds1da177e2005-04-16 15:20:36 -070090 i = key - '0';
Borislav Petkova8fe19e2014-06-04 16:11:46 -070091 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
Michal Hocko401e4a72015-02-11 15:26:21 -080092 pr_info("Loglevel set to %d\n", i);
Linus Torvalds1da177e2005-04-16 15:20:36 -070093 console_loglevel = i;
Andrew Mortonbf36b902006-03-25 03:07:08 -080094}
Linus Torvalds1da177e2005-04-16 15:20:36 -070095static struct sysrq_key_op sysrq_loglevel_op = {
96 .handler = sysrq_handle_loglevel,
Randy Dunlap208b95c2009-01-06 14:41:13 -080097 .help_msg = "loglevel(0-9)",
Linus Torvalds1da177e2005-04-16 15:20:36 -070098 .action_msg = "Changing Loglevel",
99 .enable_mask = SYSRQ_ENABLE_LOG,
100};
101
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102#ifdef CONFIG_VT
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700103static void sysrq_handle_SAK(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104{
Eric W. Biederman8b6312f2007-02-10 01:44:34 -0800105 struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
Eric W. Biederman8b6312f2007-02-10 01:44:34 -0800106 schedule_work(SAK_work);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107}
108static struct sysrq_key_op sysrq_SAK_op = {
109 .handler = sysrq_handle_SAK,
zhangwei(Jovi)afa80cc2013-03-07 17:00:02 +0800110 .help_msg = "sak(k)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 .action_msg = "SAK",
112 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
113};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800114#else
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700115#define sysrq_SAK_op (*(struct sysrq_key_op *)NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116#endif
117
118#ifdef CONFIG_VT
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700119static void sysrq_handle_unraw(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120{
Alan Cox079c9532012-02-28 14:49:23 +0000121 vt_reset_unicode(fg_console);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122}
Alan Cox079c9532012-02-28 14:49:23 +0000123
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124static struct sysrq_key_op sysrq_unraw_op = {
125 .handler = sysrq_handle_unraw,
zhangwei(Jovi)afa80cc2013-03-07 17:00:02 +0800126 .help_msg = "unraw(r)",
Bill Nottingham2e8ecb92007-10-16 23:29:38 -0700127 .action_msg = "Keyboard mode set to system default",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
129};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800130#else
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700131#define sysrq_unraw_op (*(struct sysrq_key_op *)NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132#endif /* CONFIG_VT */
133
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700134static void sysrq_handle_crash(int key)
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700135{
Neil Hormand6580a92009-06-17 16:28:17 -0700136 char *killer = NULL;
Hidetoshi Setocab8bd32009-07-29 15:04:14 -0700137
Ani Sinha984cf352015-12-17 17:15:10 -0800138 /* we need to release the RCU read lock here,
139 * otherwise we get an annoying
140 * 'BUG: sleeping function called from invalid context'
141 * complaint from the kernel before the panic.
142 */
143 rcu_read_unlock();
Hidetoshi Setocab8bd32009-07-29 15:04:14 -0700144 panic_on_oops = 1; /* force panic */
145 wmb();
Neil Hormand6580a92009-06-17 16:28:17 -0700146 *killer = 1;
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700147}
Hidetoshi Setocab8bd32009-07-29 15:04:14 -0700148static struct sysrq_key_op sysrq_crash_op = {
Neil Hormand6580a92009-06-17 16:28:17 -0700149 .handler = sysrq_handle_crash,
zhangwei(Jovi)afa80cc2013-03-07 17:00:02 +0800150 .help_msg = "crash(c)",
Neil Hormand6580a92009-06-17 16:28:17 -0700151 .action_msg = "Trigger a crash",
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700152 .enable_mask = SYSRQ_ENABLE_DUMP,
153};
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700154
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700155static void sysrq_handle_reboot(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156{
Peter Zijlstrab2e9c7d2006-09-30 23:28:02 -0700157 lockdep_off();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158 local_irq_enable();
Eric W. Biederman4de8b9b2005-07-26 11:51:06 -0600159 emergency_restart();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161static struct sysrq_key_op sysrq_reboot_op = {
162 .handler = sysrq_handle_reboot,
zhangwei(Jovi)afa80cc2013-03-07 17:00:02 +0800163 .help_msg = "reboot(b)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164 .action_msg = "Resetting",
165 .enable_mask = SYSRQ_ENABLE_BOOT,
166};
167
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700168static void sysrq_handle_sync(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169{
170 emergency_sync();
171}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172static struct sysrq_key_op sysrq_sync_op = {
173 .handler = sysrq_handle_sync,
zhangwei(Jovi)afa80cc2013-03-07 17:00:02 +0800174 .help_msg = "sync(s)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 .action_msg = "Emergency Sync",
176 .enable_mask = SYSRQ_ENABLE_SYNC,
177};
178
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700179static void sysrq_handle_show_timers(int key)
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800180{
181 sysrq_timer_list_show();
182}
183
184static struct sysrq_key_op sysrq_show_timers_op = {
185 .handler = sysrq_handle_show_timers,
zhangwei(Jovi)afa80cc2013-03-07 17:00:02 +0800186 .help_msg = "show-all-timers(q)",
Thomas Gleixner322acf62008-10-20 12:33:14 +0200187 .action_msg = "Show clockevent devices & pending hrtimers (no others)",
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800188};
189
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700190static void sysrq_handle_mountro(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191{
192 emergency_remount();
193}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194static struct sysrq_key_op sysrq_mountro_op = {
195 .handler = sysrq_handle_mountro,
zhangwei(Jovi)afa80cc2013-03-07 17:00:02 +0800196 .help_msg = "unmount(u)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197 .action_msg = "Emergency Remount R/O",
198 .enable_mask = SYSRQ_ENABLE_REMOUNT,
199};
200
Ingo Molnar8c645802006-07-03 00:24:56 -0700201#ifdef CONFIG_LOCKDEP
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700202static void sysrq_handle_showlocks(int key)
Ingo Molnarde5097c2006-01-09 15:59:21 -0800203{
Ingo Molnar9a11b49a2006-07-03 00:24:33 -0700204 debug_show_all_locks();
Ingo Molnarde5097c2006-01-09 15:59:21 -0800205}
Ingo Molnar8c645802006-07-03 00:24:56 -0700206
Ingo Molnarde5097c2006-01-09 15:59:21 -0800207static struct sysrq_key_op sysrq_showlocks_op = {
208 .handler = sysrq_handle_showlocks,
zhangwei(Jovi)afa80cc2013-03-07 17:00:02 +0800209 .help_msg = "show-all-locks(d)",
Ingo Molnarde5097c2006-01-09 15:59:21 -0800210 .action_msg = "Show Locks Held",
211};
Andrew Mortonbf36b902006-03-25 03:07:08 -0800212#else
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700213#define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL)
Ingo Molnarde5097c2006-01-09 15:59:21 -0800214#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215
Rik van Riel5045bca2008-04-29 00:59:21 -0700216#ifdef CONFIG_SMP
217static DEFINE_SPINLOCK(show_lock);
218
219static void showacpu(void *dummy)
220{
221 unsigned long flags;
222
223 /* Idle CPUs have no interesting backtrace. */
224 if (idle_cpu(smp_processor_id()))
225 return;
226
227 spin_lock_irqsave(&show_lock, flags);
Michal Hocko401e4a72015-02-11 15:26:21 -0800228 pr_info("CPU%d:\n", smp_processor_id());
Rik van Riel5045bca2008-04-29 00:59:21 -0700229 show_stack(NULL, NULL);
230 spin_unlock_irqrestore(&show_lock, flags);
231}
232
233static void sysrq_showregs_othercpus(struct work_struct *dummy)
234{
Ingo Molnar8b604d52008-06-27 11:52:45 +0200235 smp_call_function(showacpu, NULL, 0);
Rik van Riel5045bca2008-04-29 00:59:21 -0700236}
237
238static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
239
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700240static void sysrq_handle_showallcpus(int key)
Rik van Riel5045bca2008-04-29 00:59:21 -0700241{
Ingo Molnar47cab6a2009-08-03 09:31:54 +0200242 /*
243 * Fall back to the workqueue based printing if the
244 * backtrace printing did not succeed or the
245 * architecture has no support for it:
246 */
247 if (!trigger_all_cpu_backtrace()) {
248 struct pt_regs *regs = get_irq_regs();
249
250 if (regs) {
Michal Hocko401e4a72015-02-11 15:26:21 -0800251 pr_info("CPU%d:\n", smp_processor_id());
Ingo Molnar47cab6a2009-08-03 09:31:54 +0200252 show_regs(regs);
253 }
254 schedule_work(&sysrq_showallcpus);
255 }
Rik van Riel5045bca2008-04-29 00:59:21 -0700256}
257
258static struct sysrq_key_op sysrq_showallcpus_op = {
259 .handler = sysrq_handle_showallcpus,
zhangwei(Jovi)afa80cc2013-03-07 17:00:02 +0800260 .help_msg = "show-backtrace-all-active-cpus(l)",
Rik van Riel5045bca2008-04-29 00:59:21 -0700261 .action_msg = "Show backtrace of all active CPUs",
262 .enable_mask = SYSRQ_ENABLE_DUMP,
263};
264#endif
265
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700266static void sysrq_handle_showregs(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267{
David Howells7d12e782006-10-05 14:55:46 +0100268 struct pt_regs *regs = get_irq_regs();
269 if (regs)
270 show_regs(regs);
Ingo Molnarcdd6c482009-09-21 12:02:48 +0200271 perf_event_print_debug();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272}
273static struct sysrq_key_op sysrq_showregs_op = {
274 .handler = sysrq_handle_showregs,
zhangwei(Jovi)afa80cc2013-03-07 17:00:02 +0800275 .help_msg = "show-registers(p)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 .action_msg = "Show Regs",
277 .enable_mask = SYSRQ_ENABLE_DUMP,
278};
279
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700280static void sysrq_handle_showstate(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281{
282 show_state();
Tejun Heo3494fc32015-03-09 09:22:28 -0400283 show_workqueue_state();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284}
285static struct sysrq_key_op sysrq_showstate_op = {
286 .handler = sysrq_handle_showstate,
zhangwei(Jovi)afa80cc2013-03-07 17:00:02 +0800287 .help_msg = "show-task-states(t)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288 .action_msg = "Show State",
289 .enable_mask = SYSRQ_ENABLE_DUMP,
290};
291
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700292static void sysrq_handle_showstate_blocked(int key)
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800293{
294 show_state_filter(TASK_UNINTERRUPTIBLE);
295}
296static struct sysrq_key_op sysrq_showstate_blocked_op = {
297 .handler = sysrq_handle_showstate_blocked,
zhangwei(Jovi)afa80cc2013-03-07 17:00:02 +0800298 .help_msg = "show-blocked-tasks(w)",
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800299 .action_msg = "Show Blocked State",
300 .enable_mask = SYSRQ_ENABLE_DUMP,
301};
302
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100303#ifdef CONFIG_TRACING
304#include <linux/ftrace.h>
305
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700306static void sysrq_ftrace_dump(int key)
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100307{
Frederic Weisbeckercecbca92010-04-18 19:08:41 +0200308 ftrace_dump(DUMP_ALL);
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100309}
310static struct sysrq_key_op sysrq_ftrace_dump_op = {
311 .handler = sysrq_ftrace_dump,
zhangwei(Jovi)afa80cc2013-03-07 17:00:02 +0800312 .help_msg = "dump-ftrace-buffer(z)",
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100313 .action_msg = "Dump ftrace buffer",
314 .enable_mask = SYSRQ_ENABLE_DUMP,
315};
316#else
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700317#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100318#endif
Ingo Molnare59e2ae2006-12-06 20:35:59 -0800319
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700320static void sysrq_handle_showmem(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321{
Michal Hocko9af744d2017-02-22 15:46:16 -0800322 show_mem(0, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323}
324static struct sysrq_key_op sysrq_showmem_op = {
325 .handler = sysrq_handle_showmem,
zhangwei(Jovi)afa80cc2013-03-07 17:00:02 +0800326 .help_msg = "show-memory-usage(m)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327 .action_msg = "Show Memory",
328 .enable_mask = SYSRQ_ENABLE_DUMP,
329};
330
Andrew Mortonbf36b902006-03-25 03:07:08 -0800331/*
332 * Signal sysrq helper function. Sends a signal to all user processes.
333 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334static void send_sig_all(int sig)
335{
336 struct task_struct *p;
337
Anton Vorontsove502bab2012-02-07 10:49:39 +0400338 read_lock(&tasklist_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339 for_each_process(p) {
Anton Vorontsovd3a532a2012-02-07 10:49:51 +0400340 if (p->flags & PF_KTHREAD)
341 continue;
342 if (is_global_init(p))
343 continue;
344
Anton Vorontsovb82c3282012-04-05 14:25:05 -0700345 do_send_sig_info(sig, SEND_SIG_FORCED, p, true);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346 }
Anton Vorontsove502bab2012-02-07 10:49:39 +0400347 read_unlock(&tasklist_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348}
349
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700350static void sysrq_handle_term(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351{
352 send_sig_all(SIGTERM);
Borislav Petkova8fe19e2014-06-04 16:11:46 -0700353 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354}
355static struct sysrq_key_op sysrq_term_op = {
356 .handler = sysrq_handle_term,
zhangwei(Jovi)afa80cc2013-03-07 17:00:02 +0800357 .help_msg = "terminate-all-tasks(e)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358 .action_msg = "Terminate All Tasks",
359 .enable_mask = SYSRQ_ENABLE_SIGNAL,
360};
361
David Howells65f27f32006-11-22 14:55:48 +0000362static void moom_callback(struct work_struct *ignored)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363{
David Rientjes6e0fc462015-09-08 15:00:36 -0700364 const gfp_t gfp_mask = GFP_KERNEL;
365 struct oom_control oc = {
366 .zonelist = node_zonelist(first_memory_node, gfp_mask),
367 .nodemask = NULL,
Vladimir Davydov2a966b72016-07-26 15:22:33 -0700368 .memcg = NULL,
David Rientjes6e0fc462015-09-08 15:00:36 -0700369 .gfp_mask = gfp_mask,
David Rientjes54e9e292015-09-08 15:00:39 -0700370 .order = -1,
David Rientjes6e0fc462015-09-08 15:00:36 -0700371 };
372
Johannes Weinerdc564012015-06-24 16:57:19 -0700373 mutex_lock(&oom_lock);
David Rientjes6e0fc462015-09-08 15:00:36 -0700374 if (!out_of_memory(&oc))
Michal Hockod75da002017-05-03 14:54:57 -0700375 pr_info("OOM request ignored. No task eligible\n");
Johannes Weinerdc564012015-06-24 16:57:19 -0700376 mutex_unlock(&oom_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377}
378
David Howells65f27f32006-11-22 14:55:48 +0000379static DECLARE_WORK(moom_work, moom_callback);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700381static void sysrq_handle_moom(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382{
383 schedule_work(&moom_work);
384}
385static struct sysrq_key_op sysrq_moom_op = {
386 .handler = sysrq_handle_moom,
zhangwei(Jovi)afa80cc2013-03-07 17:00:02 +0800387 .help_msg = "memory-full-oom-kill(f)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 .action_msg = "Manual OOM execution",
Naohiro Ooiwab4236f82008-10-15 22:01:43 -0700389 .enable_mask = SYSRQ_ENABLE_SIGNAL,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390};
391
Eric Sandeenc2d75432009-03-31 15:23:46 -0700392#ifdef CONFIG_BLOCK
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700393static void sysrq_handle_thaw(int key)
Eric Sandeenc2d75432009-03-31 15:23:46 -0700394{
395 emergency_thaw_all();
396}
397static struct sysrq_key_op sysrq_thaw_op = {
398 .handler = sysrq_handle_thaw,
zhangwei(Jovi)afa80cc2013-03-07 17:00:02 +0800399 .help_msg = "thaw-filesystems(j)",
Eric Sandeenc2d75432009-03-31 15:23:46 -0700400 .action_msg = "Emergency Thaw of all frozen filesystems",
401 .enable_mask = SYSRQ_ENABLE_SIGNAL,
402};
403#endif
404
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700405static void sysrq_handle_kill(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406{
407 send_sig_all(SIGKILL);
Borislav Petkova8fe19e2014-06-04 16:11:46 -0700408 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409}
410static struct sysrq_key_op sysrq_kill_op = {
411 .handler = sysrq_handle_kill,
zhangwei(Jovi)afa80cc2013-03-07 17:00:02 +0800412 .help_msg = "kill-all-tasks(i)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 .action_msg = "Kill All Tasks",
414 .enable_mask = SYSRQ_ENABLE_SIGNAL,
415};
416
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700417static void sysrq_handle_unrt(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418{
419 normalize_rt_tasks();
420}
421static struct sysrq_key_op sysrq_unrt_op = {
422 .handler = sysrq_handle_unrt,
zhangwei(Jovi)afa80cc2013-03-07 17:00:02 +0800423 .help_msg = "nice-all-RT-tasks(n)",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 .action_msg = "Nice All RT Tasks",
425 .enable_mask = SYSRQ_ENABLE_RTNICE,
426};
427
428/* Key Operations table and lock */
429static DEFINE_SPINLOCK(sysrq_key_table_lock);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800430
431static struct sysrq_key_op *sysrq_key_table[36] = {
432 &sysrq_loglevel_op, /* 0 */
433 &sysrq_loglevel_op, /* 1 */
434 &sysrq_loglevel_op, /* 2 */
435 &sysrq_loglevel_op, /* 3 */
436 &sysrq_loglevel_op, /* 4 */
437 &sysrq_loglevel_op, /* 5 */
438 &sysrq_loglevel_op, /* 6 */
439 &sysrq_loglevel_op, /* 7 */
440 &sysrq_loglevel_op, /* 8 */
441 &sysrq_loglevel_op, /* 9 */
442
443 /*
Randy Dunlapd346cce2007-01-31 23:48:17 -0800444 * a: Don't use for system provided sysrqs, it is handled specially on
445 * sparc and will never arrive.
Andrew Mortonbf36b902006-03-25 03:07:08 -0800446 */
447 NULL, /* a */
448 &sysrq_reboot_op, /* b */
Eric Biggers5e351412017-04-03 22:50:20 -0700449 &sysrq_crash_op, /* c */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800450 &sysrq_showlocks_op, /* d */
451 &sysrq_term_op, /* e */
452 &sysrq_moom_op, /* f */
Jason Wessel364b5b72009-05-13 21:56:59 -0500453 /* g: May be registered for the kernel debugger */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800454 NULL, /* g */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700455 NULL, /* h - reserved for help */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800456 &sysrq_kill_op, /* i */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700457#ifdef CONFIG_BLOCK
458 &sysrq_thaw_op, /* j */
459#else
Andrew Mortonbf36b902006-03-25 03:07:08 -0800460 NULL, /* j */
Eric Sandeenc2d75432009-03-31 15:23:46 -0700461#endif
Andrew Mortonbf36b902006-03-25 03:07:08 -0800462 &sysrq_SAK_op, /* k */
Rik van Riel5045bca2008-04-29 00:59:21 -0700463#ifdef CONFIG_SMP
464 &sysrq_showallcpus_op, /* l */
465#else
Andrew Mortonbf36b902006-03-25 03:07:08 -0800466 NULL, /* l */
Rik van Riel5045bca2008-04-29 00:59:21 -0700467#endif
Andrew Mortonbf36b902006-03-25 03:07:08 -0800468 &sysrq_showmem_op, /* m */
469 &sysrq_unrt_op, /* n */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800470 /* o: This will often be registered as 'Off' at init time */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800471 NULL, /* o */
472 &sysrq_showregs_op, /* p */
Ingo Molnar88ad0bf62007-02-16 01:28:16 -0800473 &sysrq_show_timers_op, /* q */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800474 &sysrq_unraw_op, /* r */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800475 &sysrq_sync_op, /* s */
476 &sysrq_showstate_op, /* t */
477 &sysrq_mountro_op, /* u */
Jason Wessel364b5b72009-05-13 21:56:59 -0500478 /* v: May be registered for frame buffer console restore */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800479 NULL, /* v */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800480 &sysrq_showstate_blocked_op, /* w */
James Hogand1e9a4f2015-05-19 09:50:29 +0100481 /* x: May be registered on mips for TLB dump */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800482 /* x: May be registered on ppc/powerpc for xmon */
David S. Miller916ca142012-10-16 09:34:01 -0700483 /* x: May be registered on sparc64 for global PMU dump */
Randy Dunlapd346cce2007-01-31 23:48:17 -0800484 NULL, /* x */
David S. Miller93dae5b2008-05-19 23:46:00 -0700485 /* y: May be registered on sparc64 for global register dump */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800486 NULL, /* y */
Peter Zijlstra69f698a2008-11-01 19:53:34 +0100487 &sysrq_ftrace_dump_op, /* z */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488};
489
490/* key2index calculation, -1 on invalid index */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800491static int sysrq_key_table_key2index(int key)
492{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493 int retval;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800494
495 if ((key >= '0') && (key <= '9'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700496 retval = key - '0';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800497 else if ((key >= 'a') && (key <= 'z'))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498 retval = key + 10 - 'a';
Andrew Mortonbf36b902006-03-25 03:07:08 -0800499 else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500 retval = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501 return retval;
502}
503
504/*
505 * get and put functions for the table, exposed to modules.
506 */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800507struct sysrq_key_op *__sysrq_get_key_op(int key)
508{
509 struct sysrq_key_op *op_p = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510 int i;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800511
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512 i = sysrq_key_table_key2index(key);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800513 if (i != -1)
514 op_p = sysrq_key_table[i];
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700515
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516 return op_p;
517}
518
Andrew Mortonbf36b902006-03-25 03:07:08 -0800519static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
520{
521 int i = sysrq_key_table_key2index(key);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523 if (i != -1)
524 sysrq_key_table[i] = op_p;
525}
526
Dmitry Torokhovf3353972010-08-17 21:15:47 -0700527void __handle_sysrq(int key, bool check_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700528{
529 struct sysrq_key_op *op_p;
530 int orig_log_level;
Andrew Mortonbf36b902006-03-25 03:07:08 -0800531 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532
Rik van Riel722773a2014-06-06 14:38:14 -0700533 rcu_sysrq_start();
Rik van Riel984d74a2014-06-06 14:38:13 -0700534 rcu_read_lock();
Andy Whitcroftfb144ad2009-01-15 13:50:52 -0800535 /*
536 * Raise the apparent loglevel to maximum so that the sysrq header
537 * is shown to provide the user with positive feedback. We do not
538 * simply emit this at KERN_EMERG as that would change message
539 * routing in the consumers of /proc/kmsg.
540 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541 orig_log_level = console_loglevel;
Borislav Petkova8fe19e2014-06-04 16:11:46 -0700542 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
Michal Hocko401e4a72015-02-11 15:26:21 -0800543 pr_info("SysRq : ");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544
545 op_p = __sysrq_get_key_op(key);
546 if (op_p) {
Andrew Mortonbf36b902006-03-25 03:07:08 -0800547 /*
548 * Should we check for enabled operations (/proc/sysrq-trigger
549 * should not) and is the invoked operation enabled?
550 */
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800551 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
Michal Hocko401e4a72015-02-11 15:26:21 -0800552 pr_cont("%s\n", op_p->action_msg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553 console_loglevel = orig_log_level;
Dmitry Torokhov1495cc92010-08-17 21:15:46 -0700554 op_p->handler(key);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800555 } else {
Michal Hocko401e4a72015-02-11 15:26:21 -0800556 pr_cont("This sysrq operation is disabled.\n");
Andrew Mortonbf36b902006-03-25 03:07:08 -0800557 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558 } else {
Michal Hocko401e4a72015-02-11 15:26:21 -0800559 pr_cont("HELP : ");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700560 /* Only print the help msg once per handler */
Andrew Mortonbf36b902006-03-25 03:07:08 -0800561 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
562 if (sysrq_key_table[i]) {
563 int j;
564
565 for (j = 0; sysrq_key_table[i] !=
566 sysrq_key_table[j]; j++)
567 ;
568 if (j != i)
569 continue;
Michal Hocko401e4a72015-02-11 15:26:21 -0800570 pr_cont("%s ", sysrq_key_table[i]->help_msg);
Andrew Mortonbf36b902006-03-25 03:07:08 -0800571 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572 }
Michal Hocko401e4a72015-02-11 15:26:21 -0800573 pr_cont("\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574 console_loglevel = orig_log_level;
575 }
Rik van Riel984d74a2014-06-06 14:38:13 -0700576 rcu_read_unlock();
Rik van Riel722773a2014-06-06 14:38:14 -0700577 rcu_sysrq_end();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700578}
579
Dmitry Torokhovf3353972010-08-17 21:15:47 -0700580void handle_sysrq(int key)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581{
Ingo Molnar5d6f6472006-12-13 00:34:36 -0800582 if (sysrq_on())
Dmitry Torokhovf3353972010-08-17 21:15:47 -0700583 __handle_sysrq(key, true);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584}
Andrew Mortonbf36b902006-03-25 03:07:08 -0800585EXPORT_SYMBOL(handle_sysrq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700587#ifdef CONFIG_INPUT
Arnd Bergmannffb6e0c2015-05-26 14:45:29 -0700588static int sysrq_reset_downtime_ms;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700589
590/* Simple translation table for the SysRq keys */
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800591static const unsigned char sysrq_xlate[KEY_CNT] =
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700592 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */
593 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */
594 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */
595 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */
596 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */
597 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
598 "\r\000/"; /* 0x60 - 0x6f */
599
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800600struct sysrq_state {
601 struct input_handle handle;
602 struct work_struct reinject_work;
603 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
604 unsigned int alt;
605 unsigned int alt_use;
606 bool active;
607 bool need_reinject;
Dmitry Torokhov7ab7b5a2011-02-02 22:59:54 -0800608 bool reinjecting;
Mathieu Poirier154b7a42013-01-06 23:23:33 -0800609
610 /* reset sequence handling */
611 bool reset_canceled;
Mathieu J. Poirier3d289512013-06-05 22:51:46 -0700612 bool reset_requested;
Mathieu Poirier154b7a42013-01-06 23:23:33 -0800613 unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)];
614 int reset_seq_len;
615 int reset_seq_cnt;
616 int reset_seq_version;
Mathieu J. Poirier39030782013-04-01 22:14:19 -0700617 struct timer_list keyreset_timer;
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800618};
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700619
Mathieu Poirier154b7a42013-01-06 23:23:33 -0800620#define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */
621static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX];
622static unsigned int sysrq_reset_seq_len;
623static unsigned int sysrq_reset_seq_version = 1;
624
625static void sysrq_parse_reset_sequence(struct sysrq_state *state)
626{
627 int i;
628 unsigned short key;
629
630 state->reset_seq_cnt = 0;
631
632 for (i = 0; i < sysrq_reset_seq_len; i++) {
633 key = sysrq_reset_seq[i];
634
635 if (key == KEY_RESERVED || key > KEY_MAX)
636 break;
637
638 __set_bit(key, state->reset_keybit);
639 state->reset_seq_len++;
640
641 if (test_bit(key, state->key_down))
642 state->reset_seq_cnt++;
643 }
644
645 /* Disable reset until old keys are not released */
646 state->reset_canceled = state->reset_seq_cnt != 0;
647
648 state->reset_seq_version = sysrq_reset_seq_version;
649}
650
Mathieu J. Poirier3d289512013-06-05 22:51:46 -0700651static void sysrq_do_reset(unsigned long _state)
Mathieu J. Poirier39030782013-04-01 22:14:19 -0700652{
Mathieu J. Poirier3d289512013-06-05 22:51:46 -0700653 struct sysrq_state *state = (struct sysrq_state *) _state;
654
655 state->reset_requested = true;
656
657 sys_sync();
658 kernel_restart(NULL);
Mathieu J. Poirier39030782013-04-01 22:14:19 -0700659}
660
661static void sysrq_handle_reset_request(struct sysrq_state *state)
662{
Mathieu J. Poirier3d289512013-06-05 22:51:46 -0700663 if (state->reset_requested)
664 __handle_sysrq(sysrq_xlate[KEY_B], false);
665
Mathieu J. Poirier39030782013-04-01 22:14:19 -0700666 if (sysrq_reset_downtime_ms)
667 mod_timer(&state->keyreset_timer,
668 jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms));
669 else
Mathieu J. Poirier3d289512013-06-05 22:51:46 -0700670 sysrq_do_reset((unsigned long)state);
Mathieu J. Poirier39030782013-04-01 22:14:19 -0700671}
672
673static void sysrq_detect_reset_sequence(struct sysrq_state *state,
Mathieu Poirier154b7a42013-01-06 23:23:33 -0800674 unsigned int code, int value)
675{
676 if (!test_bit(code, state->reset_keybit)) {
677 /*
678 * Pressing any key _not_ in reset sequence cancels
Mathieu J. Poirier39030782013-04-01 22:14:19 -0700679 * the reset sequence. Also cancelling the timer in
680 * case additional keys were pressed after a reset
681 * has been requested.
Mathieu Poirier154b7a42013-01-06 23:23:33 -0800682 */
Mathieu J. Poirier39030782013-04-01 22:14:19 -0700683 if (value && state->reset_seq_cnt) {
Mathieu Poirier154b7a42013-01-06 23:23:33 -0800684 state->reset_canceled = true;
Mathieu J. Poirier39030782013-04-01 22:14:19 -0700685 del_timer(&state->keyreset_timer);
686 }
Mathieu Poirier154b7a42013-01-06 23:23:33 -0800687 } else if (value == 0) {
Mathieu J. Poirier39030782013-04-01 22:14:19 -0700688 /*
689 * Key release - all keys in the reset sequence need
690 * to be pressed and held for the reset timeout
691 * to hold.
692 */
693 del_timer(&state->keyreset_timer);
694
Mathieu Poirier154b7a42013-01-06 23:23:33 -0800695 if (--state->reset_seq_cnt == 0)
696 state->reset_canceled = false;
697 } else if (value == 1) {
698 /* key press, not autorepeat */
699 if (++state->reset_seq_cnt == state->reset_seq_len &&
700 !state->reset_canceled) {
Mathieu J. Poirier39030782013-04-01 22:14:19 -0700701 sysrq_handle_reset_request(state);
Mathieu Poirier154b7a42013-01-06 23:23:33 -0800702 }
703 }
Mathieu Poirier154b7a42013-01-06 23:23:33 -0800704}
705
Mathieu J. Poirier4c076eb2013-08-03 17:22:08 -0700706#ifdef CONFIG_OF
707static void sysrq_of_get_keyreset_config(void)
708{
709 u32 key;
710 struct device_node *np;
711 struct property *prop;
712 const __be32 *p;
713
714 np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq");
715 if (!np) {
716 pr_debug("No sysrq node found");
717 return;
718 }
719
720 /* Reset in case a __weak definition was present */
721 sysrq_reset_seq_len = 0;
722
723 of_property_for_each_u32(np, "keyset", prop, p, key) {
724 if (key == KEY_RESERVED || key > KEY_MAX ||
725 sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX)
726 break;
727
728 sysrq_reset_seq[sysrq_reset_seq_len++] = (unsigned short)key;
729 }
730
731 /* Get reset timeout if any. */
732 of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms);
733}
734#else
735static void sysrq_of_get_keyreset_config(void)
736{
737}
738#endif
739
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800740static void sysrq_reinject_alt_sysrq(struct work_struct *work)
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700741{
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800742 struct sysrq_state *sysrq =
743 container_of(work, struct sysrq_state, reinject_work);
744 struct input_handle *handle = &sysrq->handle;
745 unsigned int alt_code = sysrq->alt_use;
746
747 if (sysrq->need_reinject) {
Dmitry Torokhov7ab7b5a2011-02-02 22:59:54 -0800748 /* we do not want the assignment to be reordered */
749 sysrq->reinjecting = true;
750 mb();
751
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800752 /* Simulate press and release of Alt + SysRq */
753 input_inject_event(handle, EV_KEY, alt_code, 1);
754 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
755 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
756
757 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
758 input_inject_event(handle, EV_KEY, alt_code, 0);
759 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
Dmitry Torokhov7ab7b5a2011-02-02 22:59:54 -0800760
761 mb();
762 sysrq->reinjecting = false;
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800763 }
764}
765
Mathieu Poirier154b7a42013-01-06 23:23:33 -0800766static bool sysrq_handle_keypress(struct sysrq_state *sysrq,
767 unsigned int code, int value)
768{
769 bool was_active = sysrq->active;
770 bool suppress;
771
772 switch (code) {
773
774 case KEY_LEFTALT:
775 case KEY_RIGHTALT:
776 if (!value) {
777 /* One of ALTs is being released */
778 if (sysrq->active && code == sysrq->alt_use)
779 sysrq->active = false;
780
781 sysrq->alt = KEY_RESERVED;
782
783 } else if (value != 2) {
784 sysrq->alt = code;
785 sysrq->need_reinject = false;
786 }
787 break;
788
789 case KEY_SYSRQ:
790 if (value == 1 && sysrq->alt != KEY_RESERVED) {
791 sysrq->active = true;
792 sysrq->alt_use = sysrq->alt;
793 /*
794 * If nothing else will be pressed we'll need
795 * to re-inject Alt-SysRq keysroke.
796 */
797 sysrq->need_reinject = true;
798 }
799
800 /*
801 * Pretend that sysrq was never pressed at all. This
802 * is needed to properly handle KGDB which will try
803 * to release all keys after exiting debugger. If we
804 * do not clear key bit it KGDB will end up sending
805 * release events for Alt and SysRq, potentially
806 * triggering print screen function.
807 */
808 if (sysrq->active)
809 clear_bit(KEY_SYSRQ, sysrq->handle.dev->key);
810
811 break;
812
813 default:
814 if (sysrq->active && value && value != 2) {
815 sysrq->need_reinject = false;
816 __handle_sysrq(sysrq_xlate[code], true);
817 }
818 break;
819 }
820
821 suppress = sysrq->active;
822
823 if (!sysrq->active) {
824
825 /*
826 * See if reset sequence has changed since the last time.
827 */
828 if (sysrq->reset_seq_version != sysrq_reset_seq_version)
829 sysrq_parse_reset_sequence(sysrq);
830
831 /*
832 * If we are not suppressing key presses keep track of
833 * keyboard state so we can release keys that have been
834 * pressed before entering SysRq mode.
835 */
836 if (value)
837 set_bit(code, sysrq->key_down);
838 else
839 clear_bit(code, sysrq->key_down);
840
841 if (was_active)
842 schedule_work(&sysrq->reinject_work);
843
Mathieu J. Poirier39030782013-04-01 22:14:19 -0700844 /* Check for reset sequence */
845 sysrq_detect_reset_sequence(sysrq, code, value);
Mathieu Poirier154b7a42013-01-06 23:23:33 -0800846
847 } else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) {
848 /*
849 * Pass on release events for keys that was pressed before
850 * entering SysRq mode.
851 */
852 suppress = false;
853 }
854
855 return suppress;
856}
857
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800858static bool sysrq_filter(struct input_handle *handle,
859 unsigned int type, unsigned int code, int value)
860{
861 struct sysrq_state *sysrq = handle->private;
Dmitry Torokhov1966cb22010-09-29 18:04:21 -0700862 bool suppress;
863
Dmitry Torokhov7ab7b5a2011-02-02 22:59:54 -0800864 /*
865 * Do not filter anything if we are in the process of re-injecting
866 * Alt+SysRq combination.
867 */
868 if (sysrq->reinjecting)
869 return false;
870
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800871 switch (type) {
Dmitry Torokhov1966cb22010-09-29 18:04:21 -0700872
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800873 case EV_SYN:
874 suppress = false;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700875 break;
876
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800877 case EV_KEY:
Mathieu Poirier154b7a42013-01-06 23:23:33 -0800878 suppress = sysrq_handle_keypress(sysrq, code, value);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700879 break;
880
881 default:
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800882 suppress = sysrq->active;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700883 break;
884 }
885
Dmitry Torokhov1966cb22010-09-29 18:04:21 -0700886 return suppress;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700887}
888
889static int sysrq_connect(struct input_handler *handler,
890 struct input_dev *dev,
891 const struct input_device_id *id)
892{
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800893 struct sysrq_state *sysrq;
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700894 int error;
895
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800896 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);
897 if (!sysrq)
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700898 return -ENOMEM;
899
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800900 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700901
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800902 sysrq->handle.dev = dev;
903 sysrq->handle.handler = handler;
904 sysrq->handle.name = "sysrq";
905 sysrq->handle.private = sysrq;
Mathieu J. Poirier3d289512013-06-05 22:51:46 -0700906 setup_timer(&sysrq->keyreset_timer,
907 sysrq_do_reset, (unsigned long)sysrq);
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800908
909 error = input_register_handle(&sysrq->handle);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700910 if (error) {
911 pr_err("Failed to register input sysrq handler, error %d\n",
912 error);
913 goto err_free;
914 }
915
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800916 error = input_open_device(&sysrq->handle);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700917 if (error) {
918 pr_err("Failed to open input device, error %d\n", error);
919 goto err_unregister;
920 }
921
922 return 0;
923
924 err_unregister:
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800925 input_unregister_handle(&sysrq->handle);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700926 err_free:
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800927 kfree(sysrq);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700928 return error;
929}
930
931static void sysrq_disconnect(struct input_handle *handle)
932{
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800933 struct sysrq_state *sysrq = handle->private;
934
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700935 input_close_device(handle);
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800936 cancel_work_sync(&sysrq->reinject_work);
Mathieu J. Poirier39030782013-04-01 22:14:19 -0700937 del_timer_sync(&sysrq->keyreset_timer);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700938 input_unregister_handle(handle);
Dmitry Torokhovfcb71932010-11-15 00:23:42 -0800939 kfree(sysrq);
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700940}
941
942/*
Dmitry Torokhov1966cb22010-09-29 18:04:21 -0700943 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all
944 * keyboards have SysRq key predefined and so user may add it to keymap
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700945 * later, but we expect all such keyboards to have left alt.
946 */
947static const struct input_device_id sysrq_ids[] = {
948 {
949 .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
950 INPUT_DEVICE_ID_MATCH_KEYBIT,
Akinobu Mita802c0382017-01-06 02:14:16 +0900951 .evbit = { [BIT_WORD(EV_KEY)] = BIT_MASK(EV_KEY) },
952 .keybit = { [BIT_WORD(KEY_LEFTALT)] = BIT_MASK(KEY_LEFTALT) },
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700953 },
954 { },
955};
956
957static struct input_handler sysrq_handler = {
958 .filter = sysrq_filter,
959 .connect = sysrq_connect,
960 .disconnect = sysrq_disconnect,
961 .name = "sysrq",
962 .id_table = sysrq_ids,
963};
964
965static bool sysrq_handler_registered;
966
967static inline void sysrq_register_handler(void)
968{
969 int error;
Mathieu Poirier154b7a42013-01-06 23:23:33 -0800970
Mathieu J. Poirier4c076eb2013-08-03 17:22:08 -0700971 sysrq_of_get_keyreset_config();
972
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -0700973 error = input_register_handler(&sysrq_handler);
974 if (error)
975 pr_err("Failed to register input handler, error %d", error);
976 else
977 sysrq_handler_registered = true;
978}
979
980static inline void sysrq_unregister_handler(void)
981{
982 if (sysrq_handler_registered) {
983 input_unregister_handler(&sysrq_handler);
984 sysrq_handler_registered = false;
985 }
986}
987
Mathieu Poirier154b7a42013-01-06 23:23:33 -0800988static int sysrq_reset_seq_param_set(const char *buffer,
989 const struct kernel_param *kp)
990{
991 unsigned long val;
992 int error;
993
Jingoo Han86b40562013-06-01 16:30:06 +0900994 error = kstrtoul(buffer, 0, &val);
Mathieu Poirier154b7a42013-01-06 23:23:33 -0800995 if (error < 0)
996 return error;
997
998 if (val > KEY_MAX)
999 return -EINVAL;
1000
1001 *((unsigned short *)kp->arg) = val;
1002 sysrq_reset_seq_version++;
1003
1004 return 0;
1005}
1006
Luis R. Rodriguez9c278472015-05-27 11:09:38 +09301007static const struct kernel_param_ops param_ops_sysrq_reset_seq = {
Mathieu Poirier154b7a42013-01-06 23:23:33 -08001008 .get = param_get_ushort,
1009 .set = sysrq_reset_seq_param_set,
1010};
1011
1012#define param_check_sysrq_reset_seq(name, p) \
1013 __param_check(name, p, unsigned short)
1014
Paul Gortmaker3bce6f62015-08-19 17:48:06 -04001015/*
1016 * not really modular, but the easiest way to keep compat with existing
1017 * bootargs behaviour is to continue using module_param here.
1018 */
Mathieu Poirier154b7a42013-01-06 23:23:33 -08001019module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq,
1020 &sysrq_reset_seq_len, 0644);
1021
Mathieu J. Poirier39030782013-04-01 22:14:19 -07001022module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644);
1023
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -07001024#else
1025
1026static inline void sysrq_register_handler(void)
1027{
1028}
1029
1030static inline void sysrq_unregister_handler(void)
1031{
1032}
1033
1034#endif /* CONFIG_INPUT */
1035
1036int sysrq_toggle_support(int enable_mask)
1037{
1038 bool was_enabled = sysrq_on();
1039
1040 sysrq_enabled = enable_mask;
1041
1042 if (was_enabled != sysrq_on()) {
1043 if (sysrq_on())
1044 sysrq_register_handler();
1045 else
1046 sysrq_unregister_handler();
1047 }
1048
1049 return 0;
1050}
1051
Adrian Bunkcf62ddc2005-11-08 21:39:47 -08001052static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
Andrew Mortonbf36b902006-03-25 03:07:08 -08001053 struct sysrq_key_op *remove_op_p)
1054{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001055 int retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001056
Rik van Riel984d74a2014-06-06 14:38:13 -07001057 spin_lock(&sysrq_key_table_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001058 if (__sysrq_get_key_op(key) == remove_op_p) {
1059 __sysrq_put_key_op(key, insert_op_p);
1060 retval = 0;
1061 } else {
1062 retval = -1;
1063 }
Rik van Riel984d74a2014-06-06 14:38:13 -07001064 spin_unlock(&sysrq_key_table_lock);
1065
1066 /*
1067 * A concurrent __handle_sysrq either got the old op or the new op.
1068 * Wait for it to go away before returning, so the code for an old
1069 * op is not freed (eg. on module unload) while it is in use.
1070 */
1071 synchronize_rcu();
1072
Linus Torvalds1da177e2005-04-16 15:20:36 -07001073 return retval;
1074}
1075
1076int register_sysrq_key(int key, struct sysrq_key_op *op_p)
1077{
1078 return __sysrq_swap_key_ops(key, op_p, NULL);
1079}
Andrew Mortonbf36b902006-03-25 03:07:08 -08001080EXPORT_SYMBOL(register_sysrq_key);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001081
1082int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
1083{
1084 return __sysrq_swap_key_ops(key, NULL, op_p);
1085}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001086EXPORT_SYMBOL(unregister_sysrq_key);
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -07001087
1088#ifdef CONFIG_PROC_FS
1089/*
1090 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
1091 */
1092static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
1093 size_t count, loff_t *ppos)
1094{
1095 if (count) {
1096 char c;
1097
1098 if (get_user(c, buf))
1099 return -EFAULT;
Dmitry Torokhovf3353972010-08-17 21:15:47 -07001100 __handle_sysrq(c, false);
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -07001101 }
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -07001102
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -07001103 return count;
1104}
1105
1106static const struct file_operations proc_sysrq_trigger_operations = {
1107 .write = write_sysrq_trigger,
Arnd Bergmann6038f372010-08-15 18:52:59 +02001108 .llseek = noop_llseek,
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -07001109};
1110
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -07001111static void sysrq_init_procfs(void)
1112{
1113 if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
1114 &proc_sysrq_trigger_operations))
1115 pr_err("Failed to register proc interface\n");
1116}
1117
1118#else
1119
1120static inline void sysrq_init_procfs(void)
1121{
1122}
1123
1124#endif /* CONFIG_PROC_FS */
1125
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -07001126static int __init sysrq_init(void)
1127{
Dmitry Torokhov97f5f0c2010-03-21 22:31:26 -07001128 sysrq_init_procfs();
1129
1130 if (sysrq_on())
1131 sysrq_register_handler();
1132
Alexey Dobriyanf40cbaa2008-10-15 22:04:23 -07001133 return 0;
1134}
Paul Gortmaker3bce6f62015-08-19 17:48:06 -04001135device_initcall(sysrq_init);