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 * sysrq_mask - Getter for sysrq_enabled mask.
69 * Return: 1 if sysrq is always enabled, enabled sysrq_key_op mask otherwise.
73 if (sysrq_always_enabled)
79 * A value of 1 means 'all', other nonzero values are an op mask:
81 static bool sysrq_on_mask(int mask)
83 return sysrq_always_enabled ||
85 (sysrq_enabled & mask);
88 static int __init sysrq_always_enabled_setup(char *str)
90 sysrq_always_enabled = true;
91 pr_info("sysrq always enabled.\n");
96 __setup("sysrq_always_enabled", sysrq_always_enabled_setup);
99 static void sysrq_handle_loglevel(int key)
104 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
105 pr_info("Loglevel set to %d\n", i);
106 console_loglevel = i;
108 static struct sysrq_key_op sysrq_loglevel_op = {
109 .handler = sysrq_handle_loglevel,
110 .help_msg = "loglevel(0-9)",
111 .action_msg = "Changing Loglevel",
112 .enable_mask = SYSRQ_ENABLE_LOG,
116 static void sysrq_handle_SAK(int key)
118 struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
119 schedule_work(SAK_work);
121 static struct sysrq_key_op sysrq_SAK_op = {
122 .handler = sysrq_handle_SAK,
123 .help_msg = "sak(k)",
125 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
128 #define sysrq_SAK_op (*(struct sysrq_key_op *)NULL)
132 static void sysrq_handle_unraw(int key)
134 vt_reset_unicode(fg_console);
137 static struct sysrq_key_op sysrq_unraw_op = {
138 .handler = sysrq_handle_unraw,
139 .help_msg = "unraw(r)",
140 .action_msg = "Keyboard mode set to system default",
141 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
144 #define sysrq_unraw_op (*(struct sysrq_key_op *)NULL)
145 #endif /* CONFIG_VT */
147 static void sysrq_handle_crash(int key)
149 /* release the RCU read lock before crashing */
152 panic("sysrq triggered crash\n");
154 static struct sysrq_key_op sysrq_crash_op = {
155 .handler = sysrq_handle_crash,
156 .help_msg = "crash(c)",
157 .action_msg = "Trigger a crash",
158 .enable_mask = SYSRQ_ENABLE_DUMP,
161 static void sysrq_handle_reboot(int key)
167 static struct sysrq_key_op sysrq_reboot_op = {
168 .handler = sysrq_handle_reboot,
169 .help_msg = "reboot(b)",
170 .action_msg = "Resetting",
171 .enable_mask = SYSRQ_ENABLE_BOOT,
174 static void sysrq_handle_sync(int key)
178 static struct sysrq_key_op sysrq_sync_op = {
179 .handler = sysrq_handle_sync,
180 .help_msg = "sync(s)",
181 .action_msg = "Emergency Sync",
182 .enable_mask = SYSRQ_ENABLE_SYNC,
185 static void sysrq_handle_show_timers(int key)
187 sysrq_timer_list_show();
190 static struct sysrq_key_op sysrq_show_timers_op = {
191 .handler = sysrq_handle_show_timers,
192 .help_msg = "show-all-timers(q)",
193 .action_msg = "Show clockevent devices & pending hrtimers (no others)",
196 static void sysrq_handle_mountro(int key)
200 static struct sysrq_key_op sysrq_mountro_op = {
201 .handler = sysrq_handle_mountro,
202 .help_msg = "unmount(u)",
203 .action_msg = "Emergency Remount R/O",
204 .enable_mask = SYSRQ_ENABLE_REMOUNT,
207 #ifdef CONFIG_LOCKDEP
208 static void sysrq_handle_showlocks(int key)
210 debug_show_all_locks();
213 static struct sysrq_key_op sysrq_showlocks_op = {
214 .handler = sysrq_handle_showlocks,
215 .help_msg = "show-all-locks(d)",
216 .action_msg = "Show Locks Held",
219 #define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL)
223 static DEFINE_RAW_SPINLOCK(show_lock);
225 static void showacpu(void *dummy)
229 /* Idle CPUs have no interesting backtrace. */
230 if (idle_cpu(smp_processor_id()))
233 raw_spin_lock_irqsave(&show_lock, flags);
234 pr_info("CPU%d:\n", smp_processor_id());
235 show_stack(NULL, NULL);
236 raw_spin_unlock_irqrestore(&show_lock, flags);
239 static void sysrq_showregs_othercpus(struct work_struct *dummy)
241 smp_call_function(showacpu, NULL, 0);
244 static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
246 static void sysrq_handle_showallcpus(int key)
249 * Fall back to the workqueue based printing if the
250 * backtrace printing did not succeed or the
251 * architecture has no support for it:
253 if (!trigger_all_cpu_backtrace()) {
254 struct pt_regs *regs = NULL;
257 regs = get_irq_regs();
259 pr_info("CPU%d:\n", smp_processor_id());
262 schedule_work(&sysrq_showallcpus);
266 static struct sysrq_key_op sysrq_showallcpus_op = {
267 .handler = sysrq_handle_showallcpus,
268 .help_msg = "show-backtrace-all-active-cpus(l)",
269 .action_msg = "Show backtrace of all active CPUs",
270 .enable_mask = SYSRQ_ENABLE_DUMP,
274 static void sysrq_handle_showregs(int key)
276 struct pt_regs *regs = NULL;
279 regs = get_irq_regs();
282 perf_event_print_debug();
284 static struct sysrq_key_op sysrq_showregs_op = {
285 .handler = sysrq_handle_showregs,
286 .help_msg = "show-registers(p)",
287 .action_msg = "Show Regs",
288 .enable_mask = SYSRQ_ENABLE_DUMP,
291 static void sysrq_handle_showstate(int key)
294 show_workqueue_state();
296 static struct sysrq_key_op sysrq_showstate_op = {
297 .handler = sysrq_handle_showstate,
298 .help_msg = "show-task-states(t)",
299 .action_msg = "Show State",
300 .enable_mask = SYSRQ_ENABLE_DUMP,
303 static void sysrq_handle_showstate_blocked(int key)
305 show_state_filter(TASK_UNINTERRUPTIBLE);
307 static struct sysrq_key_op sysrq_showstate_blocked_op = {
308 .handler = sysrq_handle_showstate_blocked,
309 .help_msg = "show-blocked-tasks(w)",
310 .action_msg = "Show Blocked State",
311 .enable_mask = SYSRQ_ENABLE_DUMP,
314 #ifdef CONFIG_TRACING
315 #include <linux/ftrace.h>
317 static void sysrq_ftrace_dump(int key)
319 ftrace_dump(DUMP_ALL);
321 static struct sysrq_key_op sysrq_ftrace_dump_op = {
322 .handler = sysrq_ftrace_dump,
323 .help_msg = "dump-ftrace-buffer(z)",
324 .action_msg = "Dump ftrace buffer",
325 .enable_mask = SYSRQ_ENABLE_DUMP,
328 #define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
331 static void sysrq_handle_showmem(int key)
335 static struct sysrq_key_op sysrq_showmem_op = {
336 .handler = sysrq_handle_showmem,
337 .help_msg = "show-memory-usage(m)",
338 .action_msg = "Show Memory",
339 .enable_mask = SYSRQ_ENABLE_DUMP,
343 * Signal sysrq helper function. Sends a signal to all user processes.
345 static void send_sig_all(int sig)
347 struct task_struct *p;
349 read_lock(&tasklist_lock);
350 for_each_process(p) {
351 if (p->flags & PF_KTHREAD)
353 if (is_global_init(p))
356 do_send_sig_info(sig, SEND_SIG_PRIV, p, PIDTYPE_MAX);
358 read_unlock(&tasklist_lock);
361 static void sysrq_handle_term(int key)
363 send_sig_all(SIGTERM);
364 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
366 static struct sysrq_key_op sysrq_term_op = {
367 .handler = sysrq_handle_term,
368 .help_msg = "terminate-all-tasks(e)",
369 .action_msg = "Terminate All Tasks",
370 .enable_mask = SYSRQ_ENABLE_SIGNAL,
373 static void moom_callback(struct work_struct *ignored)
375 const gfp_t gfp_mask = GFP_KERNEL;
376 struct oom_control oc = {
377 .zonelist = node_zonelist(first_memory_node, gfp_mask),
380 .gfp_mask = gfp_mask,
384 mutex_lock(&oom_lock);
385 if (!out_of_memory(&oc))
386 pr_info("OOM request ignored. No task eligible\n");
387 mutex_unlock(&oom_lock);
390 static DECLARE_WORK(moom_work, moom_callback);
392 static void sysrq_handle_moom(int key)
394 schedule_work(&moom_work);
396 static struct sysrq_key_op sysrq_moom_op = {
397 .handler = sysrq_handle_moom,
398 .help_msg = "memory-full-oom-kill(f)",
399 .action_msg = "Manual OOM execution",
400 .enable_mask = SYSRQ_ENABLE_SIGNAL,
404 static void sysrq_handle_thaw(int key)
406 emergency_thaw_all();
408 static struct sysrq_key_op sysrq_thaw_op = {
409 .handler = sysrq_handle_thaw,
410 .help_msg = "thaw-filesystems(j)",
411 .action_msg = "Emergency Thaw of all frozen filesystems",
412 .enable_mask = SYSRQ_ENABLE_SIGNAL,
416 static void sysrq_handle_kill(int key)
418 send_sig_all(SIGKILL);
419 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
421 static struct sysrq_key_op sysrq_kill_op = {
422 .handler = sysrq_handle_kill,
423 .help_msg = "kill-all-tasks(i)",
424 .action_msg = "Kill All Tasks",
425 .enable_mask = SYSRQ_ENABLE_SIGNAL,
428 static void sysrq_handle_unrt(int key)
430 normalize_rt_tasks();
432 static struct sysrq_key_op sysrq_unrt_op = {
433 .handler = sysrq_handle_unrt,
434 .help_msg = "nice-all-RT-tasks(n)",
435 .action_msg = "Nice All RT Tasks",
436 .enable_mask = SYSRQ_ENABLE_RTNICE,
439 /* Key Operations table and lock */
440 static DEFINE_SPINLOCK(sysrq_key_table_lock);
442 static struct sysrq_key_op *sysrq_key_table[36] = {
443 &sysrq_loglevel_op, /* 0 */
444 &sysrq_loglevel_op, /* 1 */
445 &sysrq_loglevel_op, /* 2 */
446 &sysrq_loglevel_op, /* 3 */
447 &sysrq_loglevel_op, /* 4 */
448 &sysrq_loglevel_op, /* 5 */
449 &sysrq_loglevel_op, /* 6 */
450 &sysrq_loglevel_op, /* 7 */
451 &sysrq_loglevel_op, /* 8 */
452 &sysrq_loglevel_op, /* 9 */
455 * a: Don't use for system provided sysrqs, it is handled specially on
456 * sparc and will never arrive.
459 &sysrq_reboot_op, /* b */
460 &sysrq_crash_op, /* c */
461 &sysrq_showlocks_op, /* d */
462 &sysrq_term_op, /* e */
463 &sysrq_moom_op, /* f */
464 /* g: May be registered for the kernel debugger */
466 NULL, /* h - reserved for help */
467 &sysrq_kill_op, /* i */
469 &sysrq_thaw_op, /* j */
473 &sysrq_SAK_op, /* k */
475 &sysrq_showallcpus_op, /* l */
479 &sysrq_showmem_op, /* m */
480 &sysrq_unrt_op, /* n */
481 /* o: This will often be registered as 'Off' at init time */
483 &sysrq_showregs_op, /* p */
484 &sysrq_show_timers_op, /* q */
485 &sysrq_unraw_op, /* r */
486 &sysrq_sync_op, /* s */
487 &sysrq_showstate_op, /* t */
488 &sysrq_mountro_op, /* u */
489 /* v: May be registered for frame buffer console restore */
491 &sysrq_showstate_blocked_op, /* w */
492 /* x: May be registered on mips for TLB dump */
493 /* x: May be registered on ppc/powerpc for xmon */
494 /* x: May be registered on sparc64 for global PMU dump */
496 /* y: May be registered on sparc64 for global register dump */
498 &sysrq_ftrace_dump_op, /* z */
501 /* key2index calculation, -1 on invalid index */
502 static int sysrq_key_table_key2index(int key)
506 if ((key >= '0') && (key <= '9'))
508 else if ((key >= 'a') && (key <= 'z'))
509 retval = key + 10 - 'a';
516 * get and put functions for the table, exposed to modules.
518 struct sysrq_key_op *__sysrq_get_key_op(int key)
520 struct sysrq_key_op *op_p = NULL;
523 i = sysrq_key_table_key2index(key);
525 op_p = sysrq_key_table[i];
530 static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
532 int i = sysrq_key_table_key2index(key);
535 sysrq_key_table[i] = op_p;
538 void __handle_sysrq(int key, bool check_mask)
540 struct sysrq_key_op *op_p;
542 int orig_suppress_printk;
545 orig_suppress_printk = suppress_printk;
551 * Raise the apparent loglevel to maximum so that the sysrq header
552 * is shown to provide the user with positive feedback. We do not
553 * simply emit this at KERN_EMERG as that would change message
554 * routing in the consumers of /proc/kmsg.
556 orig_log_level = console_loglevel;
557 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
559 op_p = __sysrq_get_key_op(key);
562 * Should we check for enabled operations (/proc/sysrq-trigger
563 * should not) and is the invoked operation enabled?
565 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
566 pr_info("%s\n", op_p->action_msg);
567 console_loglevel = orig_log_level;
570 pr_info("This sysrq operation is disabled.\n");
571 console_loglevel = orig_log_level;
575 /* Only print the help msg once per handler */
576 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
577 if (sysrq_key_table[i]) {
580 for (j = 0; sysrq_key_table[i] !=
581 sysrq_key_table[j]; j++)
585 pr_cont("%s ", sysrq_key_table[i]->help_msg);
589 console_loglevel = orig_log_level;
594 suppress_printk = orig_suppress_printk;
597 void handle_sysrq(int key)
600 __handle_sysrq(key, true);
602 EXPORT_SYMBOL(handle_sysrq);
605 static int sysrq_reset_downtime_ms;
607 /* Simple translation table for the SysRq keys */
608 static const unsigned char sysrq_xlate[KEY_CNT] =
609 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */
610 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */
611 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */
612 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */
613 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */
614 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
615 "\r\000/"; /* 0x60 - 0x6f */
618 struct input_handle handle;
619 struct work_struct reinject_work;
620 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
622 unsigned int alt_use;
627 /* reset sequence handling */
629 bool reset_requested;
630 unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)];
633 int reset_seq_version;
634 struct timer_list keyreset_timer;
637 #define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */
638 static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX];
639 static unsigned int sysrq_reset_seq_len;
640 static unsigned int sysrq_reset_seq_version = 1;
642 static void sysrq_parse_reset_sequence(struct sysrq_state *state)
647 state->reset_seq_cnt = 0;
649 for (i = 0; i < sysrq_reset_seq_len; i++) {
650 key = sysrq_reset_seq[i];
652 if (key == KEY_RESERVED || key > KEY_MAX)
655 __set_bit(key, state->reset_keybit);
656 state->reset_seq_len++;
658 if (test_bit(key, state->key_down))
659 state->reset_seq_cnt++;
662 /* Disable reset until old keys are not released */
663 state->reset_canceled = state->reset_seq_cnt != 0;
665 state->reset_seq_version = sysrq_reset_seq_version;
668 static void sysrq_do_reset(struct timer_list *t)
670 struct sysrq_state *state = from_timer(state, t, keyreset_timer);
672 state->reset_requested = true;
677 static void sysrq_handle_reset_request(struct sysrq_state *state)
679 if (state->reset_requested)
680 __handle_sysrq(sysrq_xlate[KEY_B], false);
682 if (sysrq_reset_downtime_ms)
683 mod_timer(&state->keyreset_timer,
684 jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms));
686 sysrq_do_reset(&state->keyreset_timer);
689 static void sysrq_detect_reset_sequence(struct sysrq_state *state,
690 unsigned int code, int value)
692 if (!test_bit(code, state->reset_keybit)) {
694 * Pressing any key _not_ in reset sequence cancels
695 * the reset sequence. Also cancelling the timer in
696 * case additional keys were pressed after a reset
697 * has been requested.
699 if (value && state->reset_seq_cnt) {
700 state->reset_canceled = true;
701 del_timer(&state->keyreset_timer);
703 } else if (value == 0) {
705 * Key release - all keys in the reset sequence need
706 * to be pressed and held for the reset timeout
709 del_timer(&state->keyreset_timer);
711 if (--state->reset_seq_cnt == 0)
712 state->reset_canceled = false;
713 } else if (value == 1) {
714 /* key press, not autorepeat */
715 if (++state->reset_seq_cnt == state->reset_seq_len &&
716 !state->reset_canceled) {
717 sysrq_handle_reset_request(state);
723 static void sysrq_of_get_keyreset_config(void)
726 struct device_node *np;
727 struct property *prop;
730 np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq");
732 pr_debug("No sysrq node found");
736 /* Reset in case a __weak definition was present */
737 sysrq_reset_seq_len = 0;
739 of_property_for_each_u32(np, "keyset", prop, p, key) {
740 if (key == KEY_RESERVED || key > KEY_MAX ||
741 sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX)
744 sysrq_reset_seq[sysrq_reset_seq_len++] = (unsigned short)key;
747 /* Get reset timeout if any. */
748 of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms);
753 static void sysrq_of_get_keyreset_config(void)
758 static void sysrq_reinject_alt_sysrq(struct work_struct *work)
760 struct sysrq_state *sysrq =
761 container_of(work, struct sysrq_state, reinject_work);
762 struct input_handle *handle = &sysrq->handle;
763 unsigned int alt_code = sysrq->alt_use;
765 if (sysrq->need_reinject) {
766 /* we do not want the assignment to be reordered */
767 sysrq->reinjecting = true;
770 /* Simulate press and release of Alt + SysRq */
771 input_inject_event(handle, EV_KEY, alt_code, 1);
772 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
773 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
775 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
776 input_inject_event(handle, EV_KEY, alt_code, 0);
777 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
780 sysrq->reinjecting = false;
784 static bool sysrq_handle_keypress(struct sysrq_state *sysrq,
785 unsigned int code, int value)
787 bool was_active = sysrq->active;
795 /* One of ALTs is being released */
796 if (sysrq->active && code == sysrq->alt_use)
797 sysrq->active = false;
799 sysrq->alt = KEY_RESERVED;
801 } else if (value != 2) {
803 sysrq->need_reinject = false;
808 if (value == 1 && sysrq->alt != KEY_RESERVED) {
809 sysrq->active = true;
810 sysrq->alt_use = sysrq->alt;
812 * If nothing else will be pressed we'll need
813 * to re-inject Alt-SysRq keysroke.
815 sysrq->need_reinject = true;
819 * Pretend that sysrq was never pressed at all. This
820 * is needed to properly handle KGDB which will try
821 * to release all keys after exiting debugger. If we
822 * do not clear key bit it KGDB will end up sending
823 * release events for Alt and SysRq, potentially
824 * triggering print screen function.
827 clear_bit(KEY_SYSRQ, sysrq->handle.dev->key);
832 if (sysrq->active && value && value != 2) {
833 sysrq->need_reinject = false;
834 __handle_sysrq(sysrq_xlate[code], true);
839 suppress = sysrq->active;
841 if (!sysrq->active) {
844 * See if reset sequence has changed since the last time.
846 if (sysrq->reset_seq_version != sysrq_reset_seq_version)
847 sysrq_parse_reset_sequence(sysrq);
850 * If we are not suppressing key presses keep track of
851 * keyboard state so we can release keys that have been
852 * pressed before entering SysRq mode.
855 set_bit(code, sysrq->key_down);
857 clear_bit(code, sysrq->key_down);
860 schedule_work(&sysrq->reinject_work);
862 /* Check for reset sequence */
863 sysrq_detect_reset_sequence(sysrq, code, value);
865 } else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) {
867 * Pass on release events for keys that was pressed before
868 * entering SysRq mode.
876 static bool sysrq_filter(struct input_handle *handle,
877 unsigned int type, unsigned int code, int value)
879 struct sysrq_state *sysrq = handle->private;
883 * Do not filter anything if we are in the process of re-injecting
884 * Alt+SysRq combination.
886 if (sysrq->reinjecting)
896 suppress = sysrq_handle_keypress(sysrq, code, value);
900 suppress = sysrq->active;
907 static int sysrq_connect(struct input_handler *handler,
908 struct input_dev *dev,
909 const struct input_device_id *id)
911 struct sysrq_state *sysrq;
914 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);
918 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
920 sysrq->handle.dev = dev;
921 sysrq->handle.handler = handler;
922 sysrq->handle.name = "sysrq";
923 sysrq->handle.private = sysrq;
924 timer_setup(&sysrq->keyreset_timer, sysrq_do_reset, 0);
926 error = input_register_handle(&sysrq->handle);
928 pr_err("Failed to register input sysrq handler, error %d\n",
933 error = input_open_device(&sysrq->handle);
935 pr_err("Failed to open input device, error %d\n", error);
942 input_unregister_handle(&sysrq->handle);
948 static void sysrq_disconnect(struct input_handle *handle)
950 struct sysrq_state *sysrq = handle->private;
952 input_close_device(handle);
953 cancel_work_sync(&sysrq->reinject_work);
954 del_timer_sync(&sysrq->keyreset_timer);
955 input_unregister_handle(handle);
960 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all
961 * keyboards have SysRq key predefined and so user may add it to keymap
962 * later, but we expect all such keyboards to have left alt.
964 static const struct input_device_id sysrq_ids[] = {
966 .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
967 INPUT_DEVICE_ID_MATCH_KEYBIT,
968 .evbit = { [BIT_WORD(EV_KEY)] = BIT_MASK(EV_KEY) },
969 .keybit = { [BIT_WORD(KEY_LEFTALT)] = BIT_MASK(KEY_LEFTALT) },
974 static struct input_handler sysrq_handler = {
975 .filter = sysrq_filter,
976 .connect = sysrq_connect,
977 .disconnect = sysrq_disconnect,
979 .id_table = sysrq_ids,
982 static inline void sysrq_register_handler(void)
986 sysrq_of_get_keyreset_config();
988 error = input_register_handler(&sysrq_handler);
990 pr_err("Failed to register input handler, error %d", error);
993 static inline void sysrq_unregister_handler(void)
995 input_unregister_handler(&sysrq_handler);
998 static int sysrq_reset_seq_param_set(const char *buffer,
999 const struct kernel_param *kp)
1004 error = kstrtoul(buffer, 0, &val);
1011 *((unsigned short *)kp->arg) = val;
1012 sysrq_reset_seq_version++;
1017 static const struct kernel_param_ops param_ops_sysrq_reset_seq = {
1018 .get = param_get_ushort,
1019 .set = sysrq_reset_seq_param_set,
1022 #define param_check_sysrq_reset_seq(name, p) \
1023 __param_check(name, p, unsigned short)
1026 * not really modular, but the easiest way to keep compat with existing
1027 * bootargs behaviour is to continue using module_param here.
1029 module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq,
1030 &sysrq_reset_seq_len, 0644);
1032 module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644);
1036 static inline void sysrq_register_handler(void)
1040 static inline void sysrq_unregister_handler(void)
1044 #endif /* CONFIG_INPUT */
1046 int sysrq_toggle_support(int enable_mask)
1048 bool was_enabled = sysrq_on();
1050 sysrq_enabled = enable_mask;
1052 if (was_enabled != sysrq_on()) {
1054 sysrq_register_handler();
1056 sysrq_unregister_handler();
1062 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
1063 struct sysrq_key_op *remove_op_p)
1067 spin_lock(&sysrq_key_table_lock);
1068 if (__sysrq_get_key_op(key) == remove_op_p) {
1069 __sysrq_put_key_op(key, insert_op_p);
1074 spin_unlock(&sysrq_key_table_lock);
1077 * A concurrent __handle_sysrq either got the old op or the new op.
1078 * Wait for it to go away before returning, so the code for an old
1079 * op is not freed (eg. on module unload) while it is in use.
1086 int register_sysrq_key(int key, struct sysrq_key_op *op_p)
1088 return __sysrq_swap_key_ops(key, op_p, NULL);
1090 EXPORT_SYMBOL(register_sysrq_key);
1092 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
1094 return __sysrq_swap_key_ops(key, NULL, op_p);
1096 EXPORT_SYMBOL(unregister_sysrq_key);
1098 #ifdef CONFIG_PROC_FS
1100 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
1102 static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
1103 size_t count, loff_t *ppos)
1108 if (get_user(c, buf))
1110 __handle_sysrq(c, false);
1116 static const struct proc_ops sysrq_trigger_proc_ops = {
1117 .proc_write = write_sysrq_trigger,
1118 .proc_lseek = noop_llseek,
1121 static void sysrq_init_procfs(void)
1123 if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
1124 &sysrq_trigger_proc_ops))
1125 pr_err("Failed to register proc interface\n");
1130 static inline void sysrq_init_procfs(void)
1134 #endif /* CONFIG_PROC_FS */
1136 static int __init sysrq_init(void)
1138 sysrq_init_procfs();
1141 sysrq_register_handler();
1145 device_initcall(sysrq_init);