Linux 3.11-rc3
[cris-mirror.git] / drivers / tty / sysrq.c
blobd5cc3acecfd382d820b9eb5d5c3fbebf0f105b71
1 /*
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>
20 #include <linux/mm.h>
21 #include <linux/fs.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 <asm/ptrace.h>
50 #include <asm/irq_regs.h>
52 /* Whether we react on sysrq keys or just ignore them */
53 static int __read_mostly sysrq_enabled = SYSRQ_DEFAULT_ENABLE;
54 static bool __read_mostly sysrq_always_enabled;
56 unsigned short platform_sysrq_reset_seq[] __weak = { KEY_RESERVED };
57 int sysrq_reset_downtime_ms __weak;
59 static bool sysrq_on(void)
61 return sysrq_enabled || sysrq_always_enabled;
65 * A value of 1 means 'all', other nonzero values are an op mask:
67 static bool sysrq_on_mask(int mask)
69 return sysrq_always_enabled ||
70 sysrq_enabled == 1 ||
71 (sysrq_enabled & mask);
74 static int __init sysrq_always_enabled_setup(char *str)
76 sysrq_always_enabled = true;
77 pr_info("sysrq always enabled.\n");
79 return 1;
82 __setup("sysrq_always_enabled", sysrq_always_enabled_setup);
85 static void sysrq_handle_loglevel(int key)
87 int i;
89 i = key - '0';
90 console_loglevel = 7;
91 printk("Loglevel set to %d\n", i);
92 console_loglevel = i;
94 static struct sysrq_key_op sysrq_loglevel_op = {
95 .handler = sysrq_handle_loglevel,
96 .help_msg = "loglevel(0-9)",
97 .action_msg = "Changing Loglevel",
98 .enable_mask = SYSRQ_ENABLE_LOG,
101 #ifdef CONFIG_VT
102 static void sysrq_handle_SAK(int key)
104 struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
105 schedule_work(SAK_work);
107 static struct sysrq_key_op sysrq_SAK_op = {
108 .handler = sysrq_handle_SAK,
109 .help_msg = "sak(k)",
110 .action_msg = "SAK",
111 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
113 #else
114 #define sysrq_SAK_op (*(struct sysrq_key_op *)NULL)
115 #endif
117 #ifdef CONFIG_VT
118 static void sysrq_handle_unraw(int key)
120 vt_reset_unicode(fg_console);
123 static struct sysrq_key_op sysrq_unraw_op = {
124 .handler = sysrq_handle_unraw,
125 .help_msg = "unraw(r)",
126 .action_msg = "Keyboard mode set to system default",
127 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
129 #else
130 #define sysrq_unraw_op (*(struct sysrq_key_op *)NULL)
131 #endif /* CONFIG_VT */
133 static void sysrq_handle_crash(int key)
135 char *killer = NULL;
137 panic_on_oops = 1; /* force panic */
138 wmb();
139 *killer = 1;
141 static struct sysrq_key_op sysrq_crash_op = {
142 .handler = sysrq_handle_crash,
143 .help_msg = "crash(c)",
144 .action_msg = "Trigger a crash",
145 .enable_mask = SYSRQ_ENABLE_DUMP,
148 static void sysrq_handle_reboot(int key)
150 lockdep_off();
151 local_irq_enable();
152 emergency_restart();
154 static struct sysrq_key_op sysrq_reboot_op = {
155 .handler = sysrq_handle_reboot,
156 .help_msg = "reboot(b)",
157 .action_msg = "Resetting",
158 .enable_mask = SYSRQ_ENABLE_BOOT,
161 static void sysrq_handle_sync(int key)
163 emergency_sync();
165 static struct sysrq_key_op sysrq_sync_op = {
166 .handler = sysrq_handle_sync,
167 .help_msg = "sync(s)",
168 .action_msg = "Emergency Sync",
169 .enable_mask = SYSRQ_ENABLE_SYNC,
172 static void sysrq_handle_show_timers(int key)
174 sysrq_timer_list_show();
177 static struct sysrq_key_op sysrq_show_timers_op = {
178 .handler = sysrq_handle_show_timers,
179 .help_msg = "show-all-timers(q)",
180 .action_msg = "Show clockevent devices & pending hrtimers (no others)",
183 static void sysrq_handle_mountro(int key)
185 emergency_remount();
187 static struct sysrq_key_op sysrq_mountro_op = {
188 .handler = sysrq_handle_mountro,
189 .help_msg = "unmount(u)",
190 .action_msg = "Emergency Remount R/O",
191 .enable_mask = SYSRQ_ENABLE_REMOUNT,
194 #ifdef CONFIG_LOCKDEP
195 static void sysrq_handle_showlocks(int key)
197 debug_show_all_locks();
200 static struct sysrq_key_op sysrq_showlocks_op = {
201 .handler = sysrq_handle_showlocks,
202 .help_msg = "show-all-locks(d)",
203 .action_msg = "Show Locks Held",
205 #else
206 #define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL)
207 #endif
209 #ifdef CONFIG_SMP
210 static DEFINE_SPINLOCK(show_lock);
212 static void showacpu(void *dummy)
214 unsigned long flags;
216 /* Idle CPUs have no interesting backtrace. */
217 if (idle_cpu(smp_processor_id()))
218 return;
220 spin_lock_irqsave(&show_lock, flags);
221 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
222 show_stack(NULL, NULL);
223 spin_unlock_irqrestore(&show_lock, flags);
226 static void sysrq_showregs_othercpus(struct work_struct *dummy)
228 smp_call_function(showacpu, NULL, 0);
231 static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
233 static void sysrq_handle_showallcpus(int key)
236 * Fall back to the workqueue based printing if the
237 * backtrace printing did not succeed or the
238 * architecture has no support for it:
240 if (!trigger_all_cpu_backtrace()) {
241 struct pt_regs *regs = get_irq_regs();
243 if (regs) {
244 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
245 show_regs(regs);
247 schedule_work(&sysrq_showallcpus);
251 static struct sysrq_key_op sysrq_showallcpus_op = {
252 .handler = sysrq_handle_showallcpus,
253 .help_msg = "show-backtrace-all-active-cpus(l)",
254 .action_msg = "Show backtrace of all active CPUs",
255 .enable_mask = SYSRQ_ENABLE_DUMP,
257 #endif
259 static void sysrq_handle_showregs(int key)
261 struct pt_regs *regs = get_irq_regs();
262 if (regs)
263 show_regs(regs);
264 perf_event_print_debug();
266 static struct sysrq_key_op sysrq_showregs_op = {
267 .handler = sysrq_handle_showregs,
268 .help_msg = "show-registers(p)",
269 .action_msg = "Show Regs",
270 .enable_mask = SYSRQ_ENABLE_DUMP,
273 static void sysrq_handle_showstate(int key)
275 show_state();
277 static struct sysrq_key_op sysrq_showstate_op = {
278 .handler = sysrq_handle_showstate,
279 .help_msg = "show-task-states(t)",
280 .action_msg = "Show State",
281 .enable_mask = SYSRQ_ENABLE_DUMP,
284 static void sysrq_handle_showstate_blocked(int key)
286 show_state_filter(TASK_UNINTERRUPTIBLE);
288 static struct sysrq_key_op sysrq_showstate_blocked_op = {
289 .handler = sysrq_handle_showstate_blocked,
290 .help_msg = "show-blocked-tasks(w)",
291 .action_msg = "Show Blocked State",
292 .enable_mask = SYSRQ_ENABLE_DUMP,
295 #ifdef CONFIG_TRACING
296 #include <linux/ftrace.h>
298 static void sysrq_ftrace_dump(int key)
300 ftrace_dump(DUMP_ALL);
302 static struct sysrq_key_op sysrq_ftrace_dump_op = {
303 .handler = sysrq_ftrace_dump,
304 .help_msg = "dump-ftrace-buffer(z)",
305 .action_msg = "Dump ftrace buffer",
306 .enable_mask = SYSRQ_ENABLE_DUMP,
308 #else
309 #define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
310 #endif
312 static void sysrq_handle_showmem(int key)
314 show_mem(0);
316 static struct sysrq_key_op sysrq_showmem_op = {
317 .handler = sysrq_handle_showmem,
318 .help_msg = "show-memory-usage(m)",
319 .action_msg = "Show Memory",
320 .enable_mask = SYSRQ_ENABLE_DUMP,
324 * Signal sysrq helper function. Sends a signal to all user processes.
326 static void send_sig_all(int sig)
328 struct task_struct *p;
330 read_lock(&tasklist_lock);
331 for_each_process(p) {
332 if (p->flags & PF_KTHREAD)
333 continue;
334 if (is_global_init(p))
335 continue;
337 do_send_sig_info(sig, SEND_SIG_FORCED, p, true);
339 read_unlock(&tasklist_lock);
342 static void sysrq_handle_term(int key)
344 send_sig_all(SIGTERM);
345 console_loglevel = 8;
347 static struct sysrq_key_op sysrq_term_op = {
348 .handler = sysrq_handle_term,
349 .help_msg = "terminate-all-tasks(e)",
350 .action_msg = "Terminate All Tasks",
351 .enable_mask = SYSRQ_ENABLE_SIGNAL,
354 static void moom_callback(struct work_struct *ignored)
356 out_of_memory(node_zonelist(first_online_node, GFP_KERNEL), GFP_KERNEL,
357 0, NULL, true);
360 static DECLARE_WORK(moom_work, moom_callback);
362 static void sysrq_handle_moom(int key)
364 schedule_work(&moom_work);
366 static struct sysrq_key_op sysrq_moom_op = {
367 .handler = sysrq_handle_moom,
368 .help_msg = "memory-full-oom-kill(f)",
369 .action_msg = "Manual OOM execution",
370 .enable_mask = SYSRQ_ENABLE_SIGNAL,
373 #ifdef CONFIG_BLOCK
374 static void sysrq_handle_thaw(int key)
376 emergency_thaw_all();
378 static struct sysrq_key_op sysrq_thaw_op = {
379 .handler = sysrq_handle_thaw,
380 .help_msg = "thaw-filesystems(j)",
381 .action_msg = "Emergency Thaw of all frozen filesystems",
382 .enable_mask = SYSRQ_ENABLE_SIGNAL,
384 #endif
386 static void sysrq_handle_kill(int key)
388 send_sig_all(SIGKILL);
389 console_loglevel = 8;
391 static struct sysrq_key_op sysrq_kill_op = {
392 .handler = sysrq_handle_kill,
393 .help_msg = "kill-all-tasks(i)",
394 .action_msg = "Kill All Tasks",
395 .enable_mask = SYSRQ_ENABLE_SIGNAL,
398 static void sysrq_handle_unrt(int key)
400 normalize_rt_tasks();
402 static struct sysrq_key_op sysrq_unrt_op = {
403 .handler = sysrq_handle_unrt,
404 .help_msg = "nice-all-RT-tasks(n)",
405 .action_msg = "Nice All RT Tasks",
406 .enable_mask = SYSRQ_ENABLE_RTNICE,
409 /* Key Operations table and lock */
410 static DEFINE_SPINLOCK(sysrq_key_table_lock);
412 static struct sysrq_key_op *sysrq_key_table[36] = {
413 &sysrq_loglevel_op, /* 0 */
414 &sysrq_loglevel_op, /* 1 */
415 &sysrq_loglevel_op, /* 2 */
416 &sysrq_loglevel_op, /* 3 */
417 &sysrq_loglevel_op, /* 4 */
418 &sysrq_loglevel_op, /* 5 */
419 &sysrq_loglevel_op, /* 6 */
420 &sysrq_loglevel_op, /* 7 */
421 &sysrq_loglevel_op, /* 8 */
422 &sysrq_loglevel_op, /* 9 */
425 * a: Don't use for system provided sysrqs, it is handled specially on
426 * sparc and will never arrive.
428 NULL, /* a */
429 &sysrq_reboot_op, /* b */
430 &sysrq_crash_op, /* c & ibm_emac driver debug */
431 &sysrq_showlocks_op, /* d */
432 &sysrq_term_op, /* e */
433 &sysrq_moom_op, /* f */
434 /* g: May be registered for the kernel debugger */
435 NULL, /* g */
436 NULL, /* h - reserved for help */
437 &sysrq_kill_op, /* i */
438 #ifdef CONFIG_BLOCK
439 &sysrq_thaw_op, /* j */
440 #else
441 NULL, /* j */
442 #endif
443 &sysrq_SAK_op, /* k */
444 #ifdef CONFIG_SMP
445 &sysrq_showallcpus_op, /* l */
446 #else
447 NULL, /* l */
448 #endif
449 &sysrq_showmem_op, /* m */
450 &sysrq_unrt_op, /* n */
451 /* o: This will often be registered as 'Off' at init time */
452 NULL, /* o */
453 &sysrq_showregs_op, /* p */
454 &sysrq_show_timers_op, /* q */
455 &sysrq_unraw_op, /* r */
456 &sysrq_sync_op, /* s */
457 &sysrq_showstate_op, /* t */
458 &sysrq_mountro_op, /* u */
459 /* v: May be registered for frame buffer console restore */
460 NULL, /* v */
461 &sysrq_showstate_blocked_op, /* w */
462 /* x: May be registered on ppc/powerpc for xmon */
463 /* x: May be registered on sparc64 for global PMU dump */
464 NULL, /* x */
465 /* y: May be registered on sparc64 for global register dump */
466 NULL, /* y */
467 &sysrq_ftrace_dump_op, /* z */
470 /* key2index calculation, -1 on invalid index */
471 static int sysrq_key_table_key2index(int key)
473 int retval;
475 if ((key >= '0') && (key <= '9'))
476 retval = key - '0';
477 else if ((key >= 'a') && (key <= 'z'))
478 retval = key + 10 - 'a';
479 else
480 retval = -1;
481 return retval;
485 * get and put functions for the table, exposed to modules.
487 struct sysrq_key_op *__sysrq_get_key_op(int key)
489 struct sysrq_key_op *op_p = NULL;
490 int i;
492 i = sysrq_key_table_key2index(key);
493 if (i != -1)
494 op_p = sysrq_key_table[i];
496 return op_p;
499 static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
501 int i = sysrq_key_table_key2index(key);
503 if (i != -1)
504 sysrq_key_table[i] = op_p;
507 void __handle_sysrq(int key, bool check_mask)
509 struct sysrq_key_op *op_p;
510 int orig_log_level;
511 int i;
512 unsigned long flags;
514 spin_lock_irqsave(&sysrq_key_table_lock, flags);
516 * Raise the apparent loglevel to maximum so that the sysrq header
517 * is shown to provide the user with positive feedback. We do not
518 * simply emit this at KERN_EMERG as that would change message
519 * routing in the consumers of /proc/kmsg.
521 orig_log_level = console_loglevel;
522 console_loglevel = 7;
523 printk(KERN_INFO "SysRq : ");
525 op_p = __sysrq_get_key_op(key);
526 if (op_p) {
528 * Should we check for enabled operations (/proc/sysrq-trigger
529 * should not) and is the invoked operation enabled?
531 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
532 printk("%s\n", op_p->action_msg);
533 console_loglevel = orig_log_level;
534 op_p->handler(key);
535 } else {
536 printk("This sysrq operation is disabled.\n");
538 } else {
539 printk("HELP : ");
540 /* Only print the help msg once per handler */
541 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
542 if (sysrq_key_table[i]) {
543 int j;
545 for (j = 0; sysrq_key_table[i] !=
546 sysrq_key_table[j]; j++)
548 if (j != i)
549 continue;
550 printk("%s ", sysrq_key_table[i]->help_msg);
553 printk("\n");
554 console_loglevel = orig_log_level;
556 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
559 void handle_sysrq(int key)
561 if (sysrq_on())
562 __handle_sysrq(key, true);
564 EXPORT_SYMBOL(handle_sysrq);
566 #ifdef CONFIG_INPUT
568 /* Simple translation table for the SysRq keys */
569 static const unsigned char sysrq_xlate[KEY_CNT] =
570 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */
571 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */
572 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */
573 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */
574 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */
575 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
576 "\r\000/"; /* 0x60 - 0x6f */
578 struct sysrq_state {
579 struct input_handle handle;
580 struct work_struct reinject_work;
581 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
582 unsigned int alt;
583 unsigned int alt_use;
584 bool active;
585 bool need_reinject;
586 bool reinjecting;
588 /* reset sequence handling */
589 bool reset_canceled;
590 bool reset_requested;
591 unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)];
592 int reset_seq_len;
593 int reset_seq_cnt;
594 int reset_seq_version;
595 struct timer_list keyreset_timer;
598 #define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */
599 static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX];
600 static unsigned int sysrq_reset_seq_len;
601 static unsigned int sysrq_reset_seq_version = 1;
603 static void sysrq_parse_reset_sequence(struct sysrq_state *state)
605 int i;
606 unsigned short key;
608 state->reset_seq_cnt = 0;
610 for (i = 0; i < sysrq_reset_seq_len; i++) {
611 key = sysrq_reset_seq[i];
613 if (key == KEY_RESERVED || key > KEY_MAX)
614 break;
616 __set_bit(key, state->reset_keybit);
617 state->reset_seq_len++;
619 if (test_bit(key, state->key_down))
620 state->reset_seq_cnt++;
623 /* Disable reset until old keys are not released */
624 state->reset_canceled = state->reset_seq_cnt != 0;
626 state->reset_seq_version = sysrq_reset_seq_version;
629 static void sysrq_do_reset(unsigned long _state)
631 struct sysrq_state *state = (struct sysrq_state *) _state;
633 state->reset_requested = true;
635 sys_sync();
636 kernel_restart(NULL);
639 static void sysrq_handle_reset_request(struct sysrq_state *state)
641 if (state->reset_requested)
642 __handle_sysrq(sysrq_xlate[KEY_B], false);
644 if (sysrq_reset_downtime_ms)
645 mod_timer(&state->keyreset_timer,
646 jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms));
647 else
648 sysrq_do_reset((unsigned long)state);
651 static void sysrq_detect_reset_sequence(struct sysrq_state *state,
652 unsigned int code, int value)
654 if (!test_bit(code, state->reset_keybit)) {
656 * Pressing any key _not_ in reset sequence cancels
657 * the reset sequence. Also cancelling the timer in
658 * case additional keys were pressed after a reset
659 * has been requested.
661 if (value && state->reset_seq_cnt) {
662 state->reset_canceled = true;
663 del_timer(&state->keyreset_timer);
665 } else if (value == 0) {
667 * Key release - all keys in the reset sequence need
668 * to be pressed and held for the reset timeout
669 * to hold.
671 del_timer(&state->keyreset_timer);
673 if (--state->reset_seq_cnt == 0)
674 state->reset_canceled = false;
675 } else if (value == 1) {
676 /* key press, not autorepeat */
677 if (++state->reset_seq_cnt == state->reset_seq_len &&
678 !state->reset_canceled) {
679 sysrq_handle_reset_request(state);
684 static void sysrq_reinject_alt_sysrq(struct work_struct *work)
686 struct sysrq_state *sysrq =
687 container_of(work, struct sysrq_state, reinject_work);
688 struct input_handle *handle = &sysrq->handle;
689 unsigned int alt_code = sysrq->alt_use;
691 if (sysrq->need_reinject) {
692 /* we do not want the assignment to be reordered */
693 sysrq->reinjecting = true;
694 mb();
696 /* Simulate press and release of Alt + SysRq */
697 input_inject_event(handle, EV_KEY, alt_code, 1);
698 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
699 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
701 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
702 input_inject_event(handle, EV_KEY, alt_code, 0);
703 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
705 mb();
706 sysrq->reinjecting = false;
710 static bool sysrq_handle_keypress(struct sysrq_state *sysrq,
711 unsigned int code, int value)
713 bool was_active = sysrq->active;
714 bool suppress;
716 switch (code) {
718 case KEY_LEFTALT:
719 case KEY_RIGHTALT:
720 if (!value) {
721 /* One of ALTs is being released */
722 if (sysrq->active && code == sysrq->alt_use)
723 sysrq->active = false;
725 sysrq->alt = KEY_RESERVED;
727 } else if (value != 2) {
728 sysrq->alt = code;
729 sysrq->need_reinject = false;
731 break;
733 case KEY_SYSRQ:
734 if (value == 1 && sysrq->alt != KEY_RESERVED) {
735 sysrq->active = true;
736 sysrq->alt_use = sysrq->alt;
738 * If nothing else will be pressed we'll need
739 * to re-inject Alt-SysRq keysroke.
741 sysrq->need_reinject = true;
745 * Pretend that sysrq was never pressed at all. This
746 * is needed to properly handle KGDB which will try
747 * to release all keys after exiting debugger. If we
748 * do not clear key bit it KGDB will end up sending
749 * release events for Alt and SysRq, potentially
750 * triggering print screen function.
752 if (sysrq->active)
753 clear_bit(KEY_SYSRQ, sysrq->handle.dev->key);
755 break;
757 default:
758 if (sysrq->active && value && value != 2) {
759 sysrq->need_reinject = false;
760 __handle_sysrq(sysrq_xlate[code], true);
762 break;
765 suppress = sysrq->active;
767 if (!sysrq->active) {
770 * See if reset sequence has changed since the last time.
772 if (sysrq->reset_seq_version != sysrq_reset_seq_version)
773 sysrq_parse_reset_sequence(sysrq);
776 * If we are not suppressing key presses keep track of
777 * keyboard state so we can release keys that have been
778 * pressed before entering SysRq mode.
780 if (value)
781 set_bit(code, sysrq->key_down);
782 else
783 clear_bit(code, sysrq->key_down);
785 if (was_active)
786 schedule_work(&sysrq->reinject_work);
788 /* Check for reset sequence */
789 sysrq_detect_reset_sequence(sysrq, code, value);
791 } else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) {
793 * Pass on release events for keys that was pressed before
794 * entering SysRq mode.
796 suppress = false;
799 return suppress;
802 static bool sysrq_filter(struct input_handle *handle,
803 unsigned int type, unsigned int code, int value)
805 struct sysrq_state *sysrq = handle->private;
806 bool suppress;
809 * Do not filter anything if we are in the process of re-injecting
810 * Alt+SysRq combination.
812 if (sysrq->reinjecting)
813 return false;
815 switch (type) {
817 case EV_SYN:
818 suppress = false;
819 break;
821 case EV_KEY:
822 suppress = sysrq_handle_keypress(sysrq, code, value);
823 break;
825 default:
826 suppress = sysrq->active;
827 break;
830 return suppress;
833 static int sysrq_connect(struct input_handler *handler,
834 struct input_dev *dev,
835 const struct input_device_id *id)
837 struct sysrq_state *sysrq;
838 int error;
840 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);
841 if (!sysrq)
842 return -ENOMEM;
844 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
846 sysrq->handle.dev = dev;
847 sysrq->handle.handler = handler;
848 sysrq->handle.name = "sysrq";
849 sysrq->handle.private = sysrq;
850 setup_timer(&sysrq->keyreset_timer,
851 sysrq_do_reset, (unsigned long)sysrq);
853 error = input_register_handle(&sysrq->handle);
854 if (error) {
855 pr_err("Failed to register input sysrq handler, error %d\n",
856 error);
857 goto err_free;
860 error = input_open_device(&sysrq->handle);
861 if (error) {
862 pr_err("Failed to open input device, error %d\n", error);
863 goto err_unregister;
866 return 0;
868 err_unregister:
869 input_unregister_handle(&sysrq->handle);
870 err_free:
871 kfree(sysrq);
872 return error;
875 static void sysrq_disconnect(struct input_handle *handle)
877 struct sysrq_state *sysrq = handle->private;
879 input_close_device(handle);
880 cancel_work_sync(&sysrq->reinject_work);
881 del_timer_sync(&sysrq->keyreset_timer);
882 input_unregister_handle(handle);
883 kfree(sysrq);
887 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all
888 * keyboards have SysRq key predefined and so user may add it to keymap
889 * later, but we expect all such keyboards to have left alt.
891 static const struct input_device_id sysrq_ids[] = {
893 .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
894 INPUT_DEVICE_ID_MATCH_KEYBIT,
895 .evbit = { BIT_MASK(EV_KEY) },
896 .keybit = { BIT_MASK(KEY_LEFTALT) },
898 { },
901 static struct input_handler sysrq_handler = {
902 .filter = sysrq_filter,
903 .connect = sysrq_connect,
904 .disconnect = sysrq_disconnect,
905 .name = "sysrq",
906 .id_table = sysrq_ids,
909 static bool sysrq_handler_registered;
911 static inline void sysrq_register_handler(void)
913 unsigned short key;
914 int error;
915 int i;
917 for (i = 0; i < ARRAY_SIZE(sysrq_reset_seq); i++) {
918 key = platform_sysrq_reset_seq[i];
919 if (key == KEY_RESERVED || key > KEY_MAX)
920 break;
922 sysrq_reset_seq[sysrq_reset_seq_len++] = key;
925 error = input_register_handler(&sysrq_handler);
926 if (error)
927 pr_err("Failed to register input handler, error %d", error);
928 else
929 sysrq_handler_registered = true;
932 static inline void sysrq_unregister_handler(void)
934 if (sysrq_handler_registered) {
935 input_unregister_handler(&sysrq_handler);
936 sysrq_handler_registered = false;
940 static int sysrq_reset_seq_param_set(const char *buffer,
941 const struct kernel_param *kp)
943 unsigned long val;
944 int error;
946 error = kstrtoul(buffer, 0, &val);
947 if (error < 0)
948 return error;
950 if (val > KEY_MAX)
951 return -EINVAL;
953 *((unsigned short *)kp->arg) = val;
954 sysrq_reset_seq_version++;
956 return 0;
959 static struct kernel_param_ops param_ops_sysrq_reset_seq = {
960 .get = param_get_ushort,
961 .set = sysrq_reset_seq_param_set,
964 #define param_check_sysrq_reset_seq(name, p) \
965 __param_check(name, p, unsigned short)
967 module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq,
968 &sysrq_reset_seq_len, 0644);
970 module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644);
972 #else
974 static inline void sysrq_register_handler(void)
978 static inline void sysrq_unregister_handler(void)
982 #endif /* CONFIG_INPUT */
984 int sysrq_toggle_support(int enable_mask)
986 bool was_enabled = sysrq_on();
988 sysrq_enabled = enable_mask;
990 if (was_enabled != sysrq_on()) {
991 if (sysrq_on())
992 sysrq_register_handler();
993 else
994 sysrq_unregister_handler();
997 return 0;
1000 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
1001 struct sysrq_key_op *remove_op_p)
1003 int retval;
1004 unsigned long flags;
1006 spin_lock_irqsave(&sysrq_key_table_lock, flags);
1007 if (__sysrq_get_key_op(key) == remove_op_p) {
1008 __sysrq_put_key_op(key, insert_op_p);
1009 retval = 0;
1010 } else {
1011 retval = -1;
1013 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
1014 return retval;
1017 int register_sysrq_key(int key, struct sysrq_key_op *op_p)
1019 return __sysrq_swap_key_ops(key, op_p, NULL);
1021 EXPORT_SYMBOL(register_sysrq_key);
1023 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
1025 return __sysrq_swap_key_ops(key, NULL, op_p);
1027 EXPORT_SYMBOL(unregister_sysrq_key);
1029 #ifdef CONFIG_PROC_FS
1031 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
1033 static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
1034 size_t count, loff_t *ppos)
1036 if (count) {
1037 char c;
1039 if (get_user(c, buf))
1040 return -EFAULT;
1041 __handle_sysrq(c, false);
1044 return count;
1047 static const struct file_operations proc_sysrq_trigger_operations = {
1048 .write = write_sysrq_trigger,
1049 .llseek = noop_llseek,
1052 static void sysrq_init_procfs(void)
1054 if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
1055 &proc_sysrq_trigger_operations))
1056 pr_err("Failed to register proc interface\n");
1059 #else
1061 static inline void sysrq_init_procfs(void)
1065 #endif /* CONFIG_PROC_FS */
1067 static int __init sysrq_init(void)
1069 sysrq_init_procfs();
1071 if (sysrq_on())
1072 sysrq_register_handler();
1074 return 0;
1076 module_init(sysrq_init);