2 * Linux Magic System Request Key Hacks
4 * (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
5 * based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz>
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
11 * Copyright (c) 2010 Dmitry Torokhov
12 * Input handler conversion
15 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
17 #include <linux/sched.h>
18 #include <linux/sched/rt.h>
19 #include <linux/interrupt.h>
22 #include <linux/mount.h>
23 #include <linux/kdev_t.h>
24 #include <linux/major.h>
25 #include <linux/reboot.h>
26 #include <linux/sysrq.h>
27 #include <linux/kbd_kern.h>
28 #include <linux/proc_fs.h>
29 #include <linux/nmi.h>
30 #include <linux/quotaops.h>
31 #include <linux/perf_event.h>
32 #include <linux/kernel.h>
33 #include <linux/module.h>
34 #include <linux/suspend.h>
35 #include <linux/writeback.h>
36 #include <linux/swap.h>
37 #include <linux/spinlock.h>
38 #include <linux/vt_kern.h>
39 #include <linux/workqueue.h>
40 #include <linux/hrtimer.h>
41 #include <linux/oom.h>
42 #include <linux/slab.h>
43 #include <linux/input.h>
44 #include <linux/uaccess.h>
45 #include <linux/moduleparam.h>
46 #include <linux/jiffies.h>
47 #include <linux/syscalls.h>
49 #include <linux/rcupdate.h>
51 #include <asm/ptrace.h>
52 #include <asm/irq_regs.h>
54 /* Whether we react on sysrq keys or just ignore them */
55 static int __read_mostly sysrq_enabled = CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE;
56 static bool __read_mostly sysrq_always_enabled;
58 unsigned short platform_sysrq_reset_seq[] __weak = { KEY_RESERVED };
59 int sysrq_reset_downtime_ms __weak;
61 static bool sysrq_on(void)
63 return sysrq_enabled || sysrq_always_enabled;
67 * A value of 1 means 'all', other nonzero values are an op mask:
69 static bool sysrq_on_mask(int mask)
71 return sysrq_always_enabled ||
73 (sysrq_enabled & mask);
76 static int __init sysrq_always_enabled_setup(char *str)
78 sysrq_always_enabled = true;
79 pr_info("sysrq always enabled.\n");
84 __setup("sysrq_always_enabled", sysrq_always_enabled_setup);
87 static void sysrq_handle_loglevel(int key)
92 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
93 pr_info("Loglevel set to %d\n", i);
96 static struct sysrq_key_op sysrq_loglevel_op = {
97 .handler = sysrq_handle_loglevel,
98 .help_msg = "loglevel(0-9)",
99 .action_msg = "Changing Loglevel",
100 .enable_mask = SYSRQ_ENABLE_LOG,
104 static void sysrq_handle_SAK(int key)
106 struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
107 schedule_work(SAK_work);
109 static struct sysrq_key_op sysrq_SAK_op = {
110 .handler = sysrq_handle_SAK,
111 .help_msg = "sak(k)",
113 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
116 #define sysrq_SAK_op (*(struct sysrq_key_op *)NULL)
120 static void sysrq_handle_unraw(int key)
122 vt_reset_unicode(fg_console);
125 static struct sysrq_key_op sysrq_unraw_op = {
126 .handler = sysrq_handle_unraw,
127 .help_msg = "unraw(r)",
128 .action_msg = "Keyboard mode set to system default",
129 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
132 #define sysrq_unraw_op (*(struct sysrq_key_op *)NULL)
133 #endif /* CONFIG_VT */
135 static void sysrq_handle_crash(int key)
139 panic_on_oops = 1; /* force panic */
143 static struct sysrq_key_op sysrq_crash_op = {
144 .handler = sysrq_handle_crash,
145 .help_msg = "crash(c)",
146 .action_msg = "Trigger a crash",
147 .enable_mask = SYSRQ_ENABLE_DUMP,
150 static void sysrq_handle_reboot(int key)
156 static struct sysrq_key_op sysrq_reboot_op = {
157 .handler = sysrq_handle_reboot,
158 .help_msg = "reboot(b)",
159 .action_msg = "Resetting",
160 .enable_mask = SYSRQ_ENABLE_BOOT,
163 static void sysrq_handle_sync(int key)
167 static struct sysrq_key_op sysrq_sync_op = {
168 .handler = sysrq_handle_sync,
169 .help_msg = "sync(s)",
170 .action_msg = "Emergency Sync",
171 .enable_mask = SYSRQ_ENABLE_SYNC,
174 static void sysrq_handle_show_timers(int key)
176 sysrq_timer_list_show();
179 static struct sysrq_key_op sysrq_show_timers_op = {
180 .handler = sysrq_handle_show_timers,
181 .help_msg = "show-all-timers(q)",
182 .action_msg = "Show clockevent devices & pending hrtimers (no others)",
185 static void sysrq_handle_mountro(int key)
189 static struct sysrq_key_op sysrq_mountro_op = {
190 .handler = sysrq_handle_mountro,
191 .help_msg = "unmount(u)",
192 .action_msg = "Emergency Remount R/O",
193 .enable_mask = SYSRQ_ENABLE_REMOUNT,
196 #ifdef CONFIG_LOCKDEP
197 static void sysrq_handle_showlocks(int key)
199 debug_show_all_locks();
202 static struct sysrq_key_op sysrq_showlocks_op = {
203 .handler = sysrq_handle_showlocks,
204 .help_msg = "show-all-locks(d)",
205 .action_msg = "Show Locks Held",
208 #define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL)
212 static DEFINE_SPINLOCK(show_lock);
214 static void showacpu(void *dummy)
218 /* Idle CPUs have no interesting backtrace. */
219 if (idle_cpu(smp_processor_id()))
222 spin_lock_irqsave(&show_lock, flags);
223 pr_info("CPU%d:\n", smp_processor_id());
224 show_stack(NULL, NULL);
225 spin_unlock_irqrestore(&show_lock, flags);
228 static void sysrq_showregs_othercpus(struct work_struct *dummy)
230 smp_call_function(showacpu, NULL, 0);
233 static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
235 static void sysrq_handle_showallcpus(int key)
238 * Fall back to the workqueue based printing if the
239 * backtrace printing did not succeed or the
240 * architecture has no support for it:
242 if (!trigger_all_cpu_backtrace()) {
243 struct pt_regs *regs = get_irq_regs();
246 pr_info("CPU%d:\n", smp_processor_id());
249 schedule_work(&sysrq_showallcpus);
253 static struct sysrq_key_op sysrq_showallcpus_op = {
254 .handler = sysrq_handle_showallcpus,
255 .help_msg = "show-backtrace-all-active-cpus(l)",
256 .action_msg = "Show backtrace of all active CPUs",
257 .enable_mask = SYSRQ_ENABLE_DUMP,
261 static void sysrq_handle_showregs(int key)
263 struct pt_regs *regs = get_irq_regs();
266 perf_event_print_debug();
268 static struct sysrq_key_op sysrq_showregs_op = {
269 .handler = sysrq_handle_showregs,
270 .help_msg = "show-registers(p)",
271 .action_msg = "Show Regs",
272 .enable_mask = SYSRQ_ENABLE_DUMP,
275 static void sysrq_handle_showstate(int key)
279 static struct sysrq_key_op sysrq_showstate_op = {
280 .handler = sysrq_handle_showstate,
281 .help_msg = "show-task-states(t)",
282 .action_msg = "Show State",
283 .enable_mask = SYSRQ_ENABLE_DUMP,
286 static void sysrq_handle_showstate_blocked(int key)
288 show_state_filter(TASK_UNINTERRUPTIBLE);
290 static struct sysrq_key_op sysrq_showstate_blocked_op = {
291 .handler = sysrq_handle_showstate_blocked,
292 .help_msg = "show-blocked-tasks(w)",
293 .action_msg = "Show Blocked State",
294 .enable_mask = SYSRQ_ENABLE_DUMP,
297 #ifdef CONFIG_TRACING
298 #include <linux/ftrace.h>
300 static void sysrq_ftrace_dump(int key)
302 ftrace_dump(DUMP_ALL);
304 static struct sysrq_key_op sysrq_ftrace_dump_op = {
305 .handler = sysrq_ftrace_dump,
306 .help_msg = "dump-ftrace-buffer(z)",
307 .action_msg = "Dump ftrace buffer",
308 .enable_mask = SYSRQ_ENABLE_DUMP,
311 #define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
314 static void sysrq_handle_showmem(int key)
318 static struct sysrq_key_op sysrq_showmem_op = {
319 .handler = sysrq_handle_showmem,
320 .help_msg = "show-memory-usage(m)",
321 .action_msg = "Show Memory",
322 .enable_mask = SYSRQ_ENABLE_DUMP,
326 * Signal sysrq helper function. Sends a signal to all user processes.
328 static void send_sig_all(int sig)
330 struct task_struct *p;
332 read_lock(&tasklist_lock);
333 for_each_process(p) {
334 if (p->flags & PF_KTHREAD)
336 if (is_global_init(p))
339 do_send_sig_info(sig, SEND_SIG_FORCED, p, true);
341 read_unlock(&tasklist_lock);
344 static void sysrq_handle_term(int key)
346 send_sig_all(SIGTERM);
347 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
349 static struct sysrq_key_op sysrq_term_op = {
350 .handler = sysrq_handle_term,
351 .help_msg = "terminate-all-tasks(e)",
352 .action_msg = "Terminate All Tasks",
353 .enable_mask = SYSRQ_ENABLE_SIGNAL,
356 static void moom_callback(struct work_struct *ignored)
358 if (!out_of_memory(node_zonelist(first_memory_node, GFP_KERNEL),
359 GFP_KERNEL, 0, NULL, true))
360 pr_info("OOM request ignored because killer is disabled\n");
363 static DECLARE_WORK(moom_work, moom_callback);
365 static void sysrq_handle_moom(int key)
367 schedule_work(&moom_work);
369 static struct sysrq_key_op sysrq_moom_op = {
370 .handler = sysrq_handle_moom,
371 .help_msg = "memory-full-oom-kill(f)",
372 .action_msg = "Manual OOM execution",
373 .enable_mask = SYSRQ_ENABLE_SIGNAL,
377 static void sysrq_handle_thaw(int key)
379 emergency_thaw_all();
381 static struct sysrq_key_op sysrq_thaw_op = {
382 .handler = sysrq_handle_thaw,
383 .help_msg = "thaw-filesystems(j)",
384 .action_msg = "Emergency Thaw of all frozen filesystems",
385 .enable_mask = SYSRQ_ENABLE_SIGNAL,
389 static void sysrq_handle_kill(int key)
391 send_sig_all(SIGKILL);
392 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
394 static struct sysrq_key_op sysrq_kill_op = {
395 .handler = sysrq_handle_kill,
396 .help_msg = "kill-all-tasks(i)",
397 .action_msg = "Kill All Tasks",
398 .enable_mask = SYSRQ_ENABLE_SIGNAL,
401 static void sysrq_handle_unrt(int key)
403 normalize_rt_tasks();
405 static struct sysrq_key_op sysrq_unrt_op = {
406 .handler = sysrq_handle_unrt,
407 .help_msg = "nice-all-RT-tasks(n)",
408 .action_msg = "Nice All RT Tasks",
409 .enable_mask = SYSRQ_ENABLE_RTNICE,
412 /* Key Operations table and lock */
413 static DEFINE_SPINLOCK(sysrq_key_table_lock);
415 static struct sysrq_key_op *sysrq_key_table[36] = {
416 &sysrq_loglevel_op, /* 0 */
417 &sysrq_loglevel_op, /* 1 */
418 &sysrq_loglevel_op, /* 2 */
419 &sysrq_loglevel_op, /* 3 */
420 &sysrq_loglevel_op, /* 4 */
421 &sysrq_loglevel_op, /* 5 */
422 &sysrq_loglevel_op, /* 6 */
423 &sysrq_loglevel_op, /* 7 */
424 &sysrq_loglevel_op, /* 8 */
425 &sysrq_loglevel_op, /* 9 */
428 * a: Don't use for system provided sysrqs, it is handled specially on
429 * sparc and will never arrive.
432 &sysrq_reboot_op, /* b */
433 &sysrq_crash_op, /* c & ibm_emac driver debug */
434 &sysrq_showlocks_op, /* d */
435 &sysrq_term_op, /* e */
436 &sysrq_moom_op, /* f */
437 /* g: May be registered for the kernel debugger */
439 NULL, /* h - reserved for help */
440 &sysrq_kill_op, /* i */
442 &sysrq_thaw_op, /* j */
446 &sysrq_SAK_op, /* k */
448 &sysrq_showallcpus_op, /* l */
452 &sysrq_showmem_op, /* m */
453 &sysrq_unrt_op, /* n */
454 /* o: This will often be registered as 'Off' at init time */
456 &sysrq_showregs_op, /* p */
457 &sysrq_show_timers_op, /* q */
458 &sysrq_unraw_op, /* r */
459 &sysrq_sync_op, /* s */
460 &sysrq_showstate_op, /* t */
461 &sysrq_mountro_op, /* u */
462 /* v: May be registered for frame buffer console restore */
464 &sysrq_showstate_blocked_op, /* w */
465 /* x: May be registered on ppc/powerpc for xmon */
466 /* x: May be registered on sparc64 for global PMU dump */
468 /* y: May be registered on sparc64 for global register dump */
470 &sysrq_ftrace_dump_op, /* z */
473 /* key2index calculation, -1 on invalid index */
474 static int sysrq_key_table_key2index(int key)
478 if ((key >= '0') && (key <= '9'))
480 else if ((key >= 'a') && (key <= 'z'))
481 retval = key + 10 - 'a';
488 * get and put functions for the table, exposed to modules.
490 struct sysrq_key_op *__sysrq_get_key_op(int key)
492 struct sysrq_key_op *op_p = NULL;
495 i = sysrq_key_table_key2index(key);
497 op_p = sysrq_key_table[i];
502 static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
504 int i = sysrq_key_table_key2index(key);
507 sysrq_key_table[i] = op_p;
510 void __handle_sysrq(int key, bool check_mask)
512 struct sysrq_key_op *op_p;
519 * Raise the apparent loglevel to maximum so that the sysrq header
520 * is shown to provide the user with positive feedback. We do not
521 * simply emit this at KERN_EMERG as that would change message
522 * routing in the consumers of /proc/kmsg.
524 orig_log_level = console_loglevel;
525 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
528 op_p = __sysrq_get_key_op(key);
531 * Should we check for enabled operations (/proc/sysrq-trigger
532 * should not) and is the invoked operation enabled?
534 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
535 pr_cont("%s\n", op_p->action_msg);
536 console_loglevel = orig_log_level;
539 pr_cont("This sysrq operation is disabled.\n");
543 /* Only print the help msg once per handler */
544 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
545 if (sysrq_key_table[i]) {
548 for (j = 0; sysrq_key_table[i] !=
549 sysrq_key_table[j]; j++)
553 pr_cont("%s ", sysrq_key_table[i]->help_msg);
557 console_loglevel = orig_log_level;
563 void handle_sysrq(int key)
566 __handle_sysrq(key, true);
568 EXPORT_SYMBOL(handle_sysrq);
572 /* Simple translation table for the SysRq keys */
573 static const unsigned char sysrq_xlate[KEY_CNT] =
574 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */
575 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */
576 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */
577 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */
578 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */
579 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
580 "\r\000/"; /* 0x60 - 0x6f */
583 struct input_handle handle;
584 struct work_struct reinject_work;
585 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
587 unsigned int alt_use;
592 /* reset sequence handling */
594 bool reset_requested;
595 unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)];
598 int reset_seq_version;
599 struct timer_list keyreset_timer;
602 #define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */
603 static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX];
604 static unsigned int sysrq_reset_seq_len;
605 static unsigned int sysrq_reset_seq_version = 1;
607 static void sysrq_parse_reset_sequence(struct sysrq_state *state)
612 state->reset_seq_cnt = 0;
614 for (i = 0; i < sysrq_reset_seq_len; i++) {
615 key = sysrq_reset_seq[i];
617 if (key == KEY_RESERVED || key > KEY_MAX)
620 __set_bit(key, state->reset_keybit);
621 state->reset_seq_len++;
623 if (test_bit(key, state->key_down))
624 state->reset_seq_cnt++;
627 /* Disable reset until old keys are not released */
628 state->reset_canceled = state->reset_seq_cnt != 0;
630 state->reset_seq_version = sysrq_reset_seq_version;
633 static void sysrq_do_reset(unsigned long _state)
635 struct sysrq_state *state = (struct sysrq_state *) _state;
637 state->reset_requested = true;
640 kernel_restart(NULL);
643 static void sysrq_handle_reset_request(struct sysrq_state *state)
645 if (state->reset_requested)
646 __handle_sysrq(sysrq_xlate[KEY_B], false);
648 if (sysrq_reset_downtime_ms)
649 mod_timer(&state->keyreset_timer,
650 jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms));
652 sysrq_do_reset((unsigned long)state);
655 static void sysrq_detect_reset_sequence(struct sysrq_state *state,
656 unsigned int code, int value)
658 if (!test_bit(code, state->reset_keybit)) {
660 * Pressing any key _not_ in reset sequence cancels
661 * the reset sequence. Also cancelling the timer in
662 * case additional keys were pressed after a reset
663 * has been requested.
665 if (value && state->reset_seq_cnt) {
666 state->reset_canceled = true;
667 del_timer(&state->keyreset_timer);
669 } else if (value == 0) {
671 * Key release - all keys in the reset sequence need
672 * to be pressed and held for the reset timeout
675 del_timer(&state->keyreset_timer);
677 if (--state->reset_seq_cnt == 0)
678 state->reset_canceled = false;
679 } else if (value == 1) {
680 /* key press, not autorepeat */
681 if (++state->reset_seq_cnt == state->reset_seq_len &&
682 !state->reset_canceled) {
683 sysrq_handle_reset_request(state);
689 static void sysrq_of_get_keyreset_config(void)
692 struct device_node *np;
693 struct property *prop;
696 np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq");
698 pr_debug("No sysrq node found");
702 /* Reset in case a __weak definition was present */
703 sysrq_reset_seq_len = 0;
705 of_property_for_each_u32(np, "keyset", prop, p, key) {
706 if (key == KEY_RESERVED || key > KEY_MAX ||
707 sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX)
710 sysrq_reset_seq[sysrq_reset_seq_len++] = (unsigned short)key;
713 /* Get reset timeout if any. */
714 of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms);
717 static void sysrq_of_get_keyreset_config(void)
722 static void sysrq_reinject_alt_sysrq(struct work_struct *work)
724 struct sysrq_state *sysrq =
725 container_of(work, struct sysrq_state, reinject_work);
726 struct input_handle *handle = &sysrq->handle;
727 unsigned int alt_code = sysrq->alt_use;
729 if (sysrq->need_reinject) {
730 /* we do not want the assignment to be reordered */
731 sysrq->reinjecting = true;
734 /* Simulate press and release of Alt + SysRq */
735 input_inject_event(handle, EV_KEY, alt_code, 1);
736 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
737 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
739 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
740 input_inject_event(handle, EV_KEY, alt_code, 0);
741 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
744 sysrq->reinjecting = false;
748 static bool sysrq_handle_keypress(struct sysrq_state *sysrq,
749 unsigned int code, int value)
751 bool was_active = sysrq->active;
759 /* One of ALTs is being released */
760 if (sysrq->active && code == sysrq->alt_use)
761 sysrq->active = false;
763 sysrq->alt = KEY_RESERVED;
765 } else if (value != 2) {
767 sysrq->need_reinject = false;
772 if (value == 1 && sysrq->alt != KEY_RESERVED) {
773 sysrq->active = true;
774 sysrq->alt_use = sysrq->alt;
776 * If nothing else will be pressed we'll need
777 * to re-inject Alt-SysRq keysroke.
779 sysrq->need_reinject = true;
783 * Pretend that sysrq was never pressed at all. This
784 * is needed to properly handle KGDB which will try
785 * to release all keys after exiting debugger. If we
786 * do not clear key bit it KGDB will end up sending
787 * release events for Alt and SysRq, potentially
788 * triggering print screen function.
791 clear_bit(KEY_SYSRQ, sysrq->handle.dev->key);
796 if (sysrq->active && value && value != 2) {
797 sysrq->need_reinject = false;
798 __handle_sysrq(sysrq_xlate[code], true);
803 suppress = sysrq->active;
805 if (!sysrq->active) {
808 * See if reset sequence has changed since the last time.
810 if (sysrq->reset_seq_version != sysrq_reset_seq_version)
811 sysrq_parse_reset_sequence(sysrq);
814 * If we are not suppressing key presses keep track of
815 * keyboard state so we can release keys that have been
816 * pressed before entering SysRq mode.
819 set_bit(code, sysrq->key_down);
821 clear_bit(code, sysrq->key_down);
824 schedule_work(&sysrq->reinject_work);
826 /* Check for reset sequence */
827 sysrq_detect_reset_sequence(sysrq, code, value);
829 } else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) {
831 * Pass on release events for keys that was pressed before
832 * entering SysRq mode.
840 static bool sysrq_filter(struct input_handle *handle,
841 unsigned int type, unsigned int code, int value)
843 struct sysrq_state *sysrq = handle->private;
847 * Do not filter anything if we are in the process of re-injecting
848 * Alt+SysRq combination.
850 if (sysrq->reinjecting)
860 suppress = sysrq_handle_keypress(sysrq, code, value);
864 suppress = sysrq->active;
871 static int sysrq_connect(struct input_handler *handler,
872 struct input_dev *dev,
873 const struct input_device_id *id)
875 struct sysrq_state *sysrq;
878 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);
882 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
884 sysrq->handle.dev = dev;
885 sysrq->handle.handler = handler;
886 sysrq->handle.name = "sysrq";
887 sysrq->handle.private = sysrq;
888 setup_timer(&sysrq->keyreset_timer,
889 sysrq_do_reset, (unsigned long)sysrq);
891 error = input_register_handle(&sysrq->handle);
893 pr_err("Failed to register input sysrq handler, error %d\n",
898 error = input_open_device(&sysrq->handle);
900 pr_err("Failed to open input device, error %d\n", error);
907 input_unregister_handle(&sysrq->handle);
913 static void sysrq_disconnect(struct input_handle *handle)
915 struct sysrq_state *sysrq = handle->private;
917 input_close_device(handle);
918 cancel_work_sync(&sysrq->reinject_work);
919 del_timer_sync(&sysrq->keyreset_timer);
920 input_unregister_handle(handle);
925 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all
926 * keyboards have SysRq key predefined and so user may add it to keymap
927 * later, but we expect all such keyboards to have left alt.
929 static const struct input_device_id sysrq_ids[] = {
931 .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
932 INPUT_DEVICE_ID_MATCH_KEYBIT,
933 .evbit = { BIT_MASK(EV_KEY) },
934 .keybit = { BIT_MASK(KEY_LEFTALT) },
939 static struct input_handler sysrq_handler = {
940 .filter = sysrq_filter,
941 .connect = sysrq_connect,
942 .disconnect = sysrq_disconnect,
944 .id_table = sysrq_ids,
947 static bool sysrq_handler_registered;
949 static inline void sysrq_register_handler(void)
955 /* First check if a __weak interface was instantiated. */
956 for (i = 0; i < ARRAY_SIZE(sysrq_reset_seq); i++) {
957 key = platform_sysrq_reset_seq[i];
958 if (key == KEY_RESERVED || key > KEY_MAX)
961 sysrq_reset_seq[sysrq_reset_seq_len++] = key;
965 * DT configuration takes precedence over anything that would
966 * have been defined via the __weak interface.
968 sysrq_of_get_keyreset_config();
970 error = input_register_handler(&sysrq_handler);
972 pr_err("Failed to register input handler, error %d", error);
974 sysrq_handler_registered = true;
977 static inline void sysrq_unregister_handler(void)
979 if (sysrq_handler_registered) {
980 input_unregister_handler(&sysrq_handler);
981 sysrq_handler_registered = false;
985 static int sysrq_reset_seq_param_set(const char *buffer,
986 const struct kernel_param *kp)
991 error = kstrtoul(buffer, 0, &val);
998 *((unsigned short *)kp->arg) = val;
999 sysrq_reset_seq_version++;
1004 static struct kernel_param_ops param_ops_sysrq_reset_seq = {
1005 .get = param_get_ushort,
1006 .set = sysrq_reset_seq_param_set,
1009 #define param_check_sysrq_reset_seq(name, p) \
1010 __param_check(name, p, unsigned short)
1012 module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq,
1013 &sysrq_reset_seq_len, 0644);
1015 module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644);
1019 static inline void sysrq_register_handler(void)
1023 static inline void sysrq_unregister_handler(void)
1027 #endif /* CONFIG_INPUT */
1029 int sysrq_toggle_support(int enable_mask)
1031 bool was_enabled = sysrq_on();
1033 sysrq_enabled = enable_mask;
1035 if (was_enabled != sysrq_on()) {
1037 sysrq_register_handler();
1039 sysrq_unregister_handler();
1045 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
1046 struct sysrq_key_op *remove_op_p)
1050 spin_lock(&sysrq_key_table_lock);
1051 if (__sysrq_get_key_op(key) == remove_op_p) {
1052 __sysrq_put_key_op(key, insert_op_p);
1057 spin_unlock(&sysrq_key_table_lock);
1060 * A concurrent __handle_sysrq either got the old op or the new op.
1061 * Wait for it to go away before returning, so the code for an old
1062 * op is not freed (eg. on module unload) while it is in use.
1069 int register_sysrq_key(int key, struct sysrq_key_op *op_p)
1071 return __sysrq_swap_key_ops(key, op_p, NULL);
1073 EXPORT_SYMBOL(register_sysrq_key);
1075 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
1077 return __sysrq_swap_key_ops(key, NULL, op_p);
1079 EXPORT_SYMBOL(unregister_sysrq_key);
1081 #ifdef CONFIG_PROC_FS
1083 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
1085 static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
1086 size_t count, loff_t *ppos)
1091 if (get_user(c, buf))
1093 __handle_sysrq(c, false);
1099 static const struct file_operations proc_sysrq_trigger_operations = {
1100 .write = write_sysrq_trigger,
1101 .llseek = noop_llseek,
1104 static void sysrq_init_procfs(void)
1106 if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
1107 &proc_sysrq_trigger_operations))
1108 pr_err("Failed to register proc interface\n");
1113 static inline void sysrq_init_procfs(void)
1117 #endif /* CONFIG_PROC_FS */
1119 static int __init sysrq_init(void)
1121 sysrq_init_procfs();
1124 sysrq_register_handler();
1128 module_init(sysrq_init);