1 // SPDX-License-Identifier: GPL-2.0
3 * Linux Magic System Request Key Hacks
5 * (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
6 * based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz>
8 * (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
9 * overhauled to use key registration
10 * based upon discusions in irc://irc.openprojects.net/#kernelnewbies
12 * Copyright (c) 2010 Dmitry Torokhov
13 * Input handler conversion
16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18 #include <linux/sched/signal.h>
19 #include <linux/sched/rt.h>
20 #include <linux/sched/debug.h>
21 #include <linux/sched/task.h>
22 #include <linux/interrupt.h>
25 #include <linux/mount.h>
26 #include <linux/kdev_t.h>
27 #include <linux/major.h>
28 #include <linux/reboot.h>
29 #include <linux/sysrq.h>
30 #include <linux/kbd_kern.h>
31 #include <linux/proc_fs.h>
32 #include <linux/nmi.h>
33 #include <linux/quotaops.h>
34 #include <linux/perf_event.h>
35 #include <linux/kernel.h>
36 #include <linux/module.h>
37 #include <linux/suspend.h>
38 #include <linux/writeback.h>
39 #include <linux/swap.h>
40 #include <linux/spinlock.h>
41 #include <linux/vt_kern.h>
42 #include <linux/workqueue.h>
43 #include <linux/hrtimer.h>
44 #include <linux/oom.h>
45 #include <linux/slab.h>
46 #include <linux/input.h>
47 #include <linux/uaccess.h>
48 #include <linux/moduleparam.h>
49 #include <linux/jiffies.h>
50 #include <linux/syscalls.h>
52 #include <linux/rcupdate.h>
54 #include <asm/ptrace.h>
55 #include <asm/irq_regs.h>
57 /* Whether we react on sysrq keys or just ignore them */
58 static int __read_mostly sysrq_enabled = CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE;
59 static bool __read_mostly sysrq_always_enabled;
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)
137 /* release the RCU read lock before crashing */
140 panic("sysrq triggered crash\n");
142 static struct sysrq_key_op sysrq_crash_op = {
143 .handler = sysrq_handle_crash,
144 .help_msg = "crash(c)",
145 .action_msg = "Trigger a crash",
146 .enable_mask = SYSRQ_ENABLE_DUMP,
149 static void sysrq_handle_reboot(int key)
155 static struct sysrq_key_op sysrq_reboot_op = {
156 .handler = sysrq_handle_reboot,
157 .help_msg = "reboot(b)",
158 .action_msg = "Resetting",
159 .enable_mask = SYSRQ_ENABLE_BOOT,
162 static void sysrq_handle_sync(int key)
166 static struct sysrq_key_op sysrq_sync_op = {
167 .handler = sysrq_handle_sync,
168 .help_msg = "sync(s)",
169 .action_msg = "Emergency Sync",
170 .enable_mask = SYSRQ_ENABLE_SYNC,
173 static void sysrq_handle_show_timers(int key)
175 sysrq_timer_list_show();
178 static struct sysrq_key_op sysrq_show_timers_op = {
179 .handler = sysrq_handle_show_timers,
180 .help_msg = "show-all-timers(q)",
181 .action_msg = "Show clockevent devices & pending hrtimers (no others)",
184 static void sysrq_handle_mountro(int key)
188 static struct sysrq_key_op sysrq_mountro_op = {
189 .handler = sysrq_handle_mountro,
190 .help_msg = "unmount(u)",
191 .action_msg = "Emergency Remount R/O",
192 .enable_mask = SYSRQ_ENABLE_REMOUNT,
195 #ifdef CONFIG_LOCKDEP
196 static void sysrq_handle_showlocks(int key)
198 debug_show_all_locks();
201 static struct sysrq_key_op sysrq_showlocks_op = {
202 .handler = sysrq_handle_showlocks,
203 .help_msg = "show-all-locks(d)",
204 .action_msg = "Show Locks Held",
207 #define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL)
211 static DEFINE_SPINLOCK(show_lock);
213 static void showacpu(void *dummy)
217 /* Idle CPUs have no interesting backtrace. */
218 if (idle_cpu(smp_processor_id()))
221 spin_lock_irqsave(&show_lock, flags);
222 pr_info("CPU%d:\n", smp_processor_id());
223 show_stack(NULL, NULL);
224 spin_unlock_irqrestore(&show_lock, flags);
227 static void sysrq_showregs_othercpus(struct work_struct *dummy)
229 smp_call_function(showacpu, NULL, 0);
232 static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
234 static void sysrq_handle_showallcpus(int key)
237 * Fall back to the workqueue based printing if the
238 * backtrace printing did not succeed or the
239 * architecture has no support for it:
241 if (!trigger_all_cpu_backtrace()) {
242 struct pt_regs *regs = NULL;
245 regs = get_irq_regs();
247 pr_info("CPU%d:\n", smp_processor_id());
250 schedule_work(&sysrq_showallcpus);
254 static struct sysrq_key_op sysrq_showallcpus_op = {
255 .handler = sysrq_handle_showallcpus,
256 .help_msg = "show-backtrace-all-active-cpus(l)",
257 .action_msg = "Show backtrace of all active CPUs",
258 .enable_mask = SYSRQ_ENABLE_DUMP,
262 static void sysrq_handle_showregs(int key)
264 struct pt_regs *regs = NULL;
267 regs = get_irq_regs();
270 perf_event_print_debug();
272 static struct sysrq_key_op sysrq_showregs_op = {
273 .handler = sysrq_handle_showregs,
274 .help_msg = "show-registers(p)",
275 .action_msg = "Show Regs",
276 .enable_mask = SYSRQ_ENABLE_DUMP,
279 static void sysrq_handle_showstate(int key)
282 show_workqueue_state();
284 static struct sysrq_key_op sysrq_showstate_op = {
285 .handler = sysrq_handle_showstate,
286 .help_msg = "show-task-states(t)",
287 .action_msg = "Show State",
288 .enable_mask = SYSRQ_ENABLE_DUMP,
291 static void sysrq_handle_showstate_blocked(int key)
293 show_state_filter(TASK_UNINTERRUPTIBLE);
295 static struct sysrq_key_op sysrq_showstate_blocked_op = {
296 .handler = sysrq_handle_showstate_blocked,
297 .help_msg = "show-blocked-tasks(w)",
298 .action_msg = "Show Blocked State",
299 .enable_mask = SYSRQ_ENABLE_DUMP,
302 #ifdef CONFIG_TRACING
303 #include <linux/ftrace.h>
305 static void sysrq_ftrace_dump(int key)
307 ftrace_dump(DUMP_ALL);
309 static struct sysrq_key_op sysrq_ftrace_dump_op = {
310 .handler = sysrq_ftrace_dump,
311 .help_msg = "dump-ftrace-buffer(z)",
312 .action_msg = "Dump ftrace buffer",
313 .enable_mask = SYSRQ_ENABLE_DUMP,
316 #define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
319 static void sysrq_handle_showmem(int key)
323 static struct sysrq_key_op sysrq_showmem_op = {
324 .handler = sysrq_handle_showmem,
325 .help_msg = "show-memory-usage(m)",
326 .action_msg = "Show Memory",
327 .enable_mask = SYSRQ_ENABLE_DUMP,
331 * Signal sysrq helper function. Sends a signal to all user processes.
333 static void send_sig_all(int sig)
335 struct task_struct *p;
337 read_lock(&tasklist_lock);
338 for_each_process(p) {
339 if (p->flags & PF_KTHREAD)
341 if (is_global_init(p))
344 do_send_sig_info(sig, SEND_SIG_PRIV, p, PIDTYPE_MAX);
346 read_unlock(&tasklist_lock);
349 static void sysrq_handle_term(int key)
351 send_sig_all(SIGTERM);
352 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
354 static struct sysrq_key_op sysrq_term_op = {
355 .handler = sysrq_handle_term,
356 .help_msg = "terminate-all-tasks(e)",
357 .action_msg = "Terminate All Tasks",
358 .enable_mask = SYSRQ_ENABLE_SIGNAL,
361 static void moom_callback(struct work_struct *ignored)
363 const gfp_t gfp_mask = GFP_KERNEL;
364 struct oom_control oc = {
365 .zonelist = node_zonelist(first_memory_node, gfp_mask),
368 .gfp_mask = gfp_mask,
372 mutex_lock(&oom_lock);
373 if (!out_of_memory(&oc))
374 pr_info("OOM request ignored. No task eligible\n");
375 mutex_unlock(&oom_lock);
378 static DECLARE_WORK(moom_work, moom_callback);
380 static void sysrq_handle_moom(int key)
382 schedule_work(&moom_work);
384 static struct sysrq_key_op sysrq_moom_op = {
385 .handler = sysrq_handle_moom,
386 .help_msg = "memory-full-oom-kill(f)",
387 .action_msg = "Manual OOM execution",
388 .enable_mask = SYSRQ_ENABLE_SIGNAL,
392 static void sysrq_handle_thaw(int key)
394 emergency_thaw_all();
396 static struct sysrq_key_op sysrq_thaw_op = {
397 .handler = sysrq_handle_thaw,
398 .help_msg = "thaw-filesystems(j)",
399 .action_msg = "Emergency Thaw of all frozen filesystems",
400 .enable_mask = SYSRQ_ENABLE_SIGNAL,
404 static void sysrq_handle_kill(int key)
406 send_sig_all(SIGKILL);
407 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
409 static struct sysrq_key_op sysrq_kill_op = {
410 .handler = sysrq_handle_kill,
411 .help_msg = "kill-all-tasks(i)",
412 .action_msg = "Kill All Tasks",
413 .enable_mask = SYSRQ_ENABLE_SIGNAL,
416 static void sysrq_handle_unrt(int key)
418 normalize_rt_tasks();
420 static struct sysrq_key_op sysrq_unrt_op = {
421 .handler = sysrq_handle_unrt,
422 .help_msg = "nice-all-RT-tasks(n)",
423 .action_msg = "Nice All RT Tasks",
424 .enable_mask = SYSRQ_ENABLE_RTNICE,
427 /* Key Operations table and lock */
428 static DEFINE_SPINLOCK(sysrq_key_table_lock);
430 static struct sysrq_key_op *sysrq_key_table[36] = {
431 &sysrq_loglevel_op, /* 0 */
432 &sysrq_loglevel_op, /* 1 */
433 &sysrq_loglevel_op, /* 2 */
434 &sysrq_loglevel_op, /* 3 */
435 &sysrq_loglevel_op, /* 4 */
436 &sysrq_loglevel_op, /* 5 */
437 &sysrq_loglevel_op, /* 6 */
438 &sysrq_loglevel_op, /* 7 */
439 &sysrq_loglevel_op, /* 8 */
440 &sysrq_loglevel_op, /* 9 */
443 * a: Don't use for system provided sysrqs, it is handled specially on
444 * sparc and will never arrive.
447 &sysrq_reboot_op, /* b */
448 &sysrq_crash_op, /* c */
449 &sysrq_showlocks_op, /* d */
450 &sysrq_term_op, /* e */
451 &sysrq_moom_op, /* f */
452 /* g: May be registered for the kernel debugger */
454 NULL, /* h - reserved for help */
455 &sysrq_kill_op, /* i */
457 &sysrq_thaw_op, /* j */
461 &sysrq_SAK_op, /* k */
463 &sysrq_showallcpus_op, /* l */
467 &sysrq_showmem_op, /* m */
468 &sysrq_unrt_op, /* n */
469 /* o: This will often be registered as 'Off' at init time */
471 &sysrq_showregs_op, /* p */
472 &sysrq_show_timers_op, /* q */
473 &sysrq_unraw_op, /* r */
474 &sysrq_sync_op, /* s */
475 &sysrq_showstate_op, /* t */
476 &sysrq_mountro_op, /* u */
477 /* v: May be registered for frame buffer console restore */
479 &sysrq_showstate_blocked_op, /* w */
480 /* x: May be registered on mips for TLB dump */
481 /* x: May be registered on ppc/powerpc for xmon */
482 /* x: May be registered on sparc64 for global PMU dump */
484 /* y: May be registered on sparc64 for global register dump */
486 &sysrq_ftrace_dump_op, /* z */
489 /* key2index calculation, -1 on invalid index */
490 static int sysrq_key_table_key2index(int key)
494 if ((key >= '0') && (key <= '9'))
496 else if ((key >= 'a') && (key <= 'z'))
497 retval = key + 10 - 'a';
504 * get and put functions for the table, exposed to modules.
506 struct sysrq_key_op *__sysrq_get_key_op(int key)
508 struct sysrq_key_op *op_p = NULL;
511 i = sysrq_key_table_key2index(key);
513 op_p = sysrq_key_table[i];
518 static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
520 int i = sysrq_key_table_key2index(key);
523 sysrq_key_table[i] = op_p;
526 void __handle_sysrq(int key, bool check_mask)
528 struct sysrq_key_op *op_p;
535 * Raise the apparent loglevel to maximum so that the sysrq header
536 * is shown to provide the user with positive feedback. We do not
537 * simply emit this at KERN_EMERG as that would change message
538 * routing in the consumers of /proc/kmsg.
540 orig_log_level = console_loglevel;
541 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
544 op_p = __sysrq_get_key_op(key);
547 * Should we check for enabled operations (/proc/sysrq-trigger
548 * should not) and is the invoked operation enabled?
550 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
551 pr_cont("%s\n", op_p->action_msg);
552 console_loglevel = orig_log_level;
555 pr_cont("This sysrq operation is disabled.\n");
559 /* Only print the help msg once per handler */
560 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
561 if (sysrq_key_table[i]) {
564 for (j = 0; sysrq_key_table[i] !=
565 sysrq_key_table[j]; j++)
569 pr_cont("%s ", sysrq_key_table[i]->help_msg);
573 console_loglevel = orig_log_level;
579 void handle_sysrq(int key)
582 __handle_sysrq(key, true);
584 EXPORT_SYMBOL(handle_sysrq);
587 static int sysrq_reset_downtime_ms;
589 /* Simple translation table for the SysRq keys */
590 static const unsigned char sysrq_xlate[KEY_CNT] =
591 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */
592 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */
593 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */
594 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */
595 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */
596 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
597 "\r\000/"; /* 0x60 - 0x6f */
600 struct input_handle handle;
601 struct work_struct reinject_work;
602 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
604 unsigned int alt_use;
609 /* reset sequence handling */
611 bool reset_requested;
612 unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)];
615 int reset_seq_version;
616 struct timer_list keyreset_timer;
619 #define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */
620 static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX];
621 static unsigned int sysrq_reset_seq_len;
622 static unsigned int sysrq_reset_seq_version = 1;
624 static void sysrq_parse_reset_sequence(struct sysrq_state *state)
629 state->reset_seq_cnt = 0;
631 for (i = 0; i < sysrq_reset_seq_len; i++) {
632 key = sysrq_reset_seq[i];
634 if (key == KEY_RESERVED || key > KEY_MAX)
637 __set_bit(key, state->reset_keybit);
638 state->reset_seq_len++;
640 if (test_bit(key, state->key_down))
641 state->reset_seq_cnt++;
644 /* Disable reset until old keys are not released */
645 state->reset_canceled = state->reset_seq_cnt != 0;
647 state->reset_seq_version = sysrq_reset_seq_version;
650 static void sysrq_do_reset(struct timer_list *t)
652 struct sysrq_state *state = from_timer(state, t, keyreset_timer);
654 state->reset_requested = true;
659 static void sysrq_handle_reset_request(struct sysrq_state *state)
661 if (state->reset_requested)
662 __handle_sysrq(sysrq_xlate[KEY_B], false);
664 if (sysrq_reset_downtime_ms)
665 mod_timer(&state->keyreset_timer,
666 jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms));
668 sysrq_do_reset(&state->keyreset_timer);
671 static void sysrq_detect_reset_sequence(struct sysrq_state *state,
672 unsigned int code, int value)
674 if (!test_bit(code, state->reset_keybit)) {
676 * Pressing any key _not_ in reset sequence cancels
677 * the reset sequence. Also cancelling the timer in
678 * case additional keys were pressed after a reset
679 * has been requested.
681 if (value && state->reset_seq_cnt) {
682 state->reset_canceled = true;
683 del_timer(&state->keyreset_timer);
685 } else if (value == 0) {
687 * Key release - all keys in the reset sequence need
688 * to be pressed and held for the reset timeout
691 del_timer(&state->keyreset_timer);
693 if (--state->reset_seq_cnt == 0)
694 state->reset_canceled = false;
695 } else if (value == 1) {
696 /* key press, not autorepeat */
697 if (++state->reset_seq_cnt == state->reset_seq_len &&
698 !state->reset_canceled) {
699 sysrq_handle_reset_request(state);
705 static void sysrq_of_get_keyreset_config(void)
708 struct device_node *np;
709 struct property *prop;
712 np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq");
714 pr_debug("No sysrq node found");
718 /* Reset in case a __weak definition was present */
719 sysrq_reset_seq_len = 0;
721 of_property_for_each_u32(np, "keyset", prop, p, key) {
722 if (key == KEY_RESERVED || key > KEY_MAX ||
723 sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX)
726 sysrq_reset_seq[sysrq_reset_seq_len++] = (unsigned short)key;
729 /* Get reset timeout if any. */
730 of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms);
735 static void sysrq_of_get_keyreset_config(void)
740 static void sysrq_reinject_alt_sysrq(struct work_struct *work)
742 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;
747 if (sysrq->need_reinject) {
748 /* we do not want the assignment to be reordered */
749 sysrq->reinjecting = true;
752 /* 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);
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);
762 sysrq->reinjecting = false;
766 static bool sysrq_handle_keypress(struct sysrq_state *sysrq,
767 unsigned int code, int value)
769 bool was_active = sysrq->active;
777 /* One of ALTs is being released */
778 if (sysrq->active && code == sysrq->alt_use)
779 sysrq->active = false;
781 sysrq->alt = KEY_RESERVED;
783 } else if (value != 2) {
785 sysrq->need_reinject = false;
790 if (value == 1 && sysrq->alt != KEY_RESERVED) {
791 sysrq->active = true;
792 sysrq->alt_use = sysrq->alt;
794 * If nothing else will be pressed we'll need
795 * to re-inject Alt-SysRq keysroke.
797 sysrq->need_reinject = true;
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.
809 clear_bit(KEY_SYSRQ, sysrq->handle.dev->key);
814 if (sysrq->active && value && value != 2) {
815 sysrq->need_reinject = false;
816 __handle_sysrq(sysrq_xlate[code], true);
821 suppress = sysrq->active;
823 if (!sysrq->active) {
826 * See if reset sequence has changed since the last time.
828 if (sysrq->reset_seq_version != sysrq_reset_seq_version)
829 sysrq_parse_reset_sequence(sysrq);
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.
837 set_bit(code, sysrq->key_down);
839 clear_bit(code, sysrq->key_down);
842 schedule_work(&sysrq->reinject_work);
844 /* Check for reset sequence */
845 sysrq_detect_reset_sequence(sysrq, code, value);
847 } else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) {
849 * Pass on release events for keys that was pressed before
850 * entering SysRq mode.
858 static bool sysrq_filter(struct input_handle *handle,
859 unsigned int type, unsigned int code, int value)
861 struct sysrq_state *sysrq = handle->private;
865 * Do not filter anything if we are in the process of re-injecting
866 * Alt+SysRq combination.
868 if (sysrq->reinjecting)
878 suppress = sysrq_handle_keypress(sysrq, code, value);
882 suppress = sysrq->active;
889 static int sysrq_connect(struct input_handler *handler,
890 struct input_dev *dev,
891 const struct input_device_id *id)
893 struct sysrq_state *sysrq;
896 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);
900 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
902 sysrq->handle.dev = dev;
903 sysrq->handle.handler = handler;
904 sysrq->handle.name = "sysrq";
905 sysrq->handle.private = sysrq;
906 timer_setup(&sysrq->keyreset_timer, sysrq_do_reset, 0);
908 error = input_register_handle(&sysrq->handle);
910 pr_err("Failed to register input sysrq handler, error %d\n",
915 error = input_open_device(&sysrq->handle);
917 pr_err("Failed to open input device, error %d\n", error);
924 input_unregister_handle(&sysrq->handle);
930 static void sysrq_disconnect(struct input_handle *handle)
932 struct sysrq_state *sysrq = handle->private;
934 input_close_device(handle);
935 cancel_work_sync(&sysrq->reinject_work);
936 del_timer_sync(&sysrq->keyreset_timer);
937 input_unregister_handle(handle);
942 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all
943 * keyboards have SysRq key predefined and so user may add it to keymap
944 * later, but we expect all such keyboards to have left alt.
946 static const struct input_device_id sysrq_ids[] = {
948 .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
949 INPUT_DEVICE_ID_MATCH_KEYBIT,
950 .evbit = { [BIT_WORD(EV_KEY)] = BIT_MASK(EV_KEY) },
951 .keybit = { [BIT_WORD(KEY_LEFTALT)] = BIT_MASK(KEY_LEFTALT) },
956 static struct input_handler sysrq_handler = {
957 .filter = sysrq_filter,
958 .connect = sysrq_connect,
959 .disconnect = sysrq_disconnect,
961 .id_table = sysrq_ids,
964 static bool sysrq_handler_registered;
966 static inline void sysrq_register_handler(void)
970 sysrq_of_get_keyreset_config();
972 error = input_register_handler(&sysrq_handler);
974 pr_err("Failed to register input handler, error %d", error);
976 sysrq_handler_registered = true;
979 static inline void sysrq_unregister_handler(void)
981 if (sysrq_handler_registered) {
982 input_unregister_handler(&sysrq_handler);
983 sysrq_handler_registered = false;
987 static int sysrq_reset_seq_param_set(const char *buffer,
988 const struct kernel_param *kp)
993 error = kstrtoul(buffer, 0, &val);
1000 *((unsigned short *)kp->arg) = val;
1001 sysrq_reset_seq_version++;
1006 static const struct kernel_param_ops param_ops_sysrq_reset_seq = {
1007 .get = param_get_ushort,
1008 .set = sysrq_reset_seq_param_set,
1011 #define param_check_sysrq_reset_seq(name, p) \
1012 __param_check(name, p, unsigned short)
1015 * not really modular, but the easiest way to keep compat with existing
1016 * bootargs behaviour is to continue using module_param here.
1018 module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq,
1019 &sysrq_reset_seq_len, 0644);
1021 module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644);
1025 static inline void sysrq_register_handler(void)
1029 static inline void sysrq_unregister_handler(void)
1033 #endif /* CONFIG_INPUT */
1035 int sysrq_toggle_support(int enable_mask)
1037 bool was_enabled = sysrq_on();
1039 sysrq_enabled = enable_mask;
1041 if (was_enabled != sysrq_on()) {
1043 sysrq_register_handler();
1045 sysrq_unregister_handler();
1051 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
1052 struct sysrq_key_op *remove_op_p)
1056 spin_lock(&sysrq_key_table_lock);
1057 if (__sysrq_get_key_op(key) == remove_op_p) {
1058 __sysrq_put_key_op(key, insert_op_p);
1063 spin_unlock(&sysrq_key_table_lock);
1066 * A concurrent __handle_sysrq either got the old op or the new op.
1067 * Wait for it to go away before returning, so the code for an old
1068 * op is not freed (eg. on module unload) while it is in use.
1075 int register_sysrq_key(int key, struct sysrq_key_op *op_p)
1077 return __sysrq_swap_key_ops(key, op_p, NULL);
1079 EXPORT_SYMBOL(register_sysrq_key);
1081 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
1083 return __sysrq_swap_key_ops(key, NULL, op_p);
1085 EXPORT_SYMBOL(unregister_sysrq_key);
1087 #ifdef CONFIG_PROC_FS
1089 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
1091 static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
1092 size_t count, loff_t *ppos)
1097 if (get_user(c, buf))
1099 __handle_sysrq(c, false);
1105 static const struct file_operations proc_sysrq_trigger_operations = {
1106 .write = write_sysrq_trigger,
1107 .llseek = noop_llseek,
1110 static void sysrq_init_procfs(void)
1112 if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
1113 &proc_sysrq_trigger_operations))
1114 pr_err("Failed to register proc interface\n");
1119 static inline void sysrq_init_procfs(void)
1123 #endif /* CONFIG_PROC_FS */
1125 static int __init sysrq_init(void)
1127 sysrq_init_procfs();
1130 sysrq_register_handler();
1134 device_initcall(sysrq_init);