602c9a74bec69b786962bf5c1d2e3a0384148efc
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / drivers / tty / sysrq.c
1 /*
2 * Linux Magic System Request Key Hacks
3 *
4 * (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
5 * based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz>
6 *
7 * (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
8 * overhauled to use key registration
9 * based upon discusions in irc://irc.openprojects.net/#kernelnewbies
10 *
11 * Copyright (c) 2010 Dmitry Torokhov
12 * Input handler conversion
13 */
14
15 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
16
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
48 #include <asm/ptrace.h>
49 #include <asm/irq_regs.h>
50
51 /* Whether we react on sysrq keys or just ignore them */
52 static int __read_mostly sysrq_enabled = SYSRQ_DEFAULT_ENABLE;
53 static bool __read_mostly sysrq_always_enabled;
54
55 unsigned short platform_sysrq_reset_seq[] __weak = { KEY_RESERVED };
56 int sysrq_reset_downtime_ms __weak;
57
58 static bool sysrq_on(void)
59 {
60 return sysrq_enabled || sysrq_always_enabled;
61 }
62
63 /*
64 * A value of 1 means 'all', other nonzero values are an op mask:
65 */
66 static bool sysrq_on_mask(int mask)
67 {
68 return sysrq_always_enabled ||
69 sysrq_enabled == 1 ||
70 (sysrq_enabled & mask);
71 }
72
73 static int __init sysrq_always_enabled_setup(char *str)
74 {
75 sysrq_always_enabled = true;
76 pr_info("sysrq always enabled.\n");
77
78 return 1;
79 }
80
81 __setup("sysrq_always_enabled", sysrq_always_enabled_setup);
82
83
84 static void sysrq_handle_loglevel(int key)
85 {
86 int i;
87
88 i = key - '0';
89 console_loglevel = 7;
90 printk("Loglevel set to %d\n", i);
91 console_loglevel = i;
92 }
93 static struct sysrq_key_op sysrq_loglevel_op = {
94 .handler = sysrq_handle_loglevel,
95 .help_msg = "loglevel(0-9)",
96 .action_msg = "Changing Loglevel",
97 .enable_mask = SYSRQ_ENABLE_LOG,
98 };
99
100 #ifdef CONFIG_VT
101 static void sysrq_handle_SAK(int key)
102 {
103 struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
104 schedule_work(SAK_work);
105 }
106 static struct sysrq_key_op sysrq_SAK_op = {
107 .handler = sysrq_handle_SAK,
108 .help_msg = "sak(k)",
109 .action_msg = "SAK",
110 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
111 };
112 #else
113 #define sysrq_SAK_op (*(struct sysrq_key_op *)NULL)
114 #endif
115
116 #ifdef CONFIG_VT
117 static void sysrq_handle_unraw(int key)
118 {
119 vt_reset_unicode(fg_console);
120 }
121
122 static struct sysrq_key_op sysrq_unraw_op = {
123 .handler = sysrq_handle_unraw,
124 .help_msg = "unraw(r)",
125 .action_msg = "Keyboard mode set to system default",
126 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
127 };
128 #else
129 #define sysrq_unraw_op (*(struct sysrq_key_op *)NULL)
130 #endif /* CONFIG_VT */
131
132 static void sysrq_handle_crash(int key)
133 {
134 char *killer = NULL;
135
136 panic_on_oops = 1; /* force panic */
137 wmb();
138 *killer = 1;
139 }
140 static struct sysrq_key_op sysrq_crash_op = {
141 .handler = sysrq_handle_crash,
142 .help_msg = "crash(c)",
143 .action_msg = "Trigger a crash",
144 .enable_mask = SYSRQ_ENABLE_DUMP,
145 };
146
147 static void sysrq_handle_reboot(int key)
148 {
149 lockdep_off();
150 local_irq_enable();
151 emergency_restart();
152 }
153 static struct sysrq_key_op sysrq_reboot_op = {
154 .handler = sysrq_handle_reboot,
155 .help_msg = "reboot(b)",
156 .action_msg = "Resetting",
157 .enable_mask = SYSRQ_ENABLE_BOOT,
158 };
159
160 static void sysrq_handle_sync(int key)
161 {
162 emergency_sync();
163 }
164 static struct sysrq_key_op sysrq_sync_op = {
165 .handler = sysrq_handle_sync,
166 .help_msg = "sync(s)",
167 .action_msg = "Emergency Sync",
168 .enable_mask = SYSRQ_ENABLE_SYNC,
169 };
170
171 static void sysrq_handle_show_timers(int key)
172 {
173 sysrq_timer_list_show();
174 }
175
176 static struct sysrq_key_op sysrq_show_timers_op = {
177 .handler = sysrq_handle_show_timers,
178 .help_msg = "show-all-timers(q)",
179 .action_msg = "Show clockevent devices & pending hrtimers (no others)",
180 };
181
182 static void sysrq_handle_mountro(int key)
183 {
184 emergency_remount();
185 }
186 static struct sysrq_key_op sysrq_mountro_op = {
187 .handler = sysrq_handle_mountro,
188 .help_msg = "unmount(u)",
189 .action_msg = "Emergency Remount R/O",
190 .enable_mask = SYSRQ_ENABLE_REMOUNT,
191 };
192
193 #ifdef CONFIG_LOCKDEP
194 static void sysrq_handle_showlocks(int key)
195 {
196 debug_show_all_locks();
197 }
198
199 static struct sysrq_key_op sysrq_showlocks_op = {
200 .handler = sysrq_handle_showlocks,
201 .help_msg = "show-all-locks(d)",
202 .action_msg = "Show Locks Held",
203 };
204 #else
205 #define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL)
206 #endif
207
208 #ifdef CONFIG_SMP
209 static DEFINE_SPINLOCK(show_lock);
210
211 static void showacpu(void *dummy)
212 {
213 unsigned long flags;
214
215 /* Idle CPUs have no interesting backtrace. */
216 if (idle_cpu(smp_processor_id()))
217 return;
218
219 spin_lock_irqsave(&show_lock, flags);
220 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
221 show_stack(NULL, NULL);
222 spin_unlock_irqrestore(&show_lock, flags);
223 }
224
225 static void sysrq_showregs_othercpus(struct work_struct *dummy)
226 {
227 smp_call_function(showacpu, NULL, 0);
228 }
229
230 static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
231
232 static void sysrq_handle_showallcpus(int key)
233 {
234 /*
235 * Fall back to the workqueue based printing if the
236 * backtrace printing did not succeed or the
237 * architecture has no support for it:
238 */
239 if (!trigger_all_cpu_backtrace()) {
240 struct pt_regs *regs = get_irq_regs();
241
242 if (regs) {
243 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
244 show_regs(regs);
245 }
246 schedule_work(&sysrq_showallcpus);
247 }
248 }
249
250 static struct sysrq_key_op sysrq_showallcpus_op = {
251 .handler = sysrq_handle_showallcpus,
252 .help_msg = "show-backtrace-all-active-cpus(l)",
253 .action_msg = "Show backtrace of all active CPUs",
254 .enable_mask = SYSRQ_ENABLE_DUMP,
255 };
256 #endif
257
258 static void sysrq_handle_showregs(int key)
259 {
260 struct pt_regs *regs = get_irq_regs();
261 if (regs)
262 show_regs(regs);
263 perf_event_print_debug();
264 }
265 static struct sysrq_key_op sysrq_showregs_op = {
266 .handler = sysrq_handle_showregs,
267 .help_msg = "show-registers(p)",
268 .action_msg = "Show Regs",
269 .enable_mask = SYSRQ_ENABLE_DUMP,
270 };
271
272 static void sysrq_handle_showstate(int key)
273 {
274 show_state();
275 }
276 static struct sysrq_key_op sysrq_showstate_op = {
277 .handler = sysrq_handle_showstate,
278 .help_msg = "show-task-states(t)",
279 .action_msg = "Show State",
280 .enable_mask = SYSRQ_ENABLE_DUMP,
281 };
282
283 static void sysrq_handle_showstate_blocked(int key)
284 {
285 show_state_filter(TASK_UNINTERRUPTIBLE);
286 }
287 static struct sysrq_key_op sysrq_showstate_blocked_op = {
288 .handler = sysrq_handle_showstate_blocked,
289 .help_msg = "show-blocked-tasks(w)",
290 .action_msg = "Show Blocked State",
291 .enable_mask = SYSRQ_ENABLE_DUMP,
292 };
293
294 #ifdef CONFIG_TRACING
295 #include <linux/ftrace.h>
296
297 static void sysrq_ftrace_dump(int key)
298 {
299 ftrace_dump(DUMP_ALL);
300 }
301 static struct sysrq_key_op sysrq_ftrace_dump_op = {
302 .handler = sysrq_ftrace_dump,
303 .help_msg = "dump-ftrace-buffer(z)",
304 .action_msg = "Dump ftrace buffer",
305 .enable_mask = SYSRQ_ENABLE_DUMP,
306 };
307 #else
308 #define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
309 #endif
310
311 static void sysrq_handle_showmem(int key)
312 {
313 show_mem(0);
314 }
315 static struct sysrq_key_op sysrq_showmem_op = {
316 .handler = sysrq_handle_showmem,
317 .help_msg = "show-memory-usage(m)",
318 .action_msg = "Show Memory",
319 .enable_mask = SYSRQ_ENABLE_DUMP,
320 };
321
322 /*
323 * Signal sysrq helper function. Sends a signal to all user processes.
324 */
325 static void send_sig_all(int sig)
326 {
327 struct task_struct *p;
328
329 read_lock(&tasklist_lock);
330 for_each_process(p) {
331 if (p->flags & PF_KTHREAD)
332 continue;
333 if (is_global_init(p))
334 continue;
335
336 do_send_sig_info(sig, SEND_SIG_FORCED, p, true);
337 }
338 read_unlock(&tasklist_lock);
339 }
340
341 static void sysrq_handle_term(int key)
342 {
343 send_sig_all(SIGTERM);
344 console_loglevel = 8;
345 }
346 static struct sysrq_key_op sysrq_term_op = {
347 .handler = sysrq_handle_term,
348 .help_msg = "terminate-all-tasks(e)",
349 .action_msg = "Terminate All Tasks",
350 .enable_mask = SYSRQ_ENABLE_SIGNAL,
351 };
352
353 static void moom_callback(struct work_struct *ignored)
354 {
355 out_of_memory(node_zonelist(first_online_node, GFP_KERNEL), GFP_KERNEL,
356 0, NULL, true);
357 }
358
359 static DECLARE_WORK(moom_work, moom_callback);
360
361 static void sysrq_handle_moom(int key)
362 {
363 schedule_work(&moom_work);
364 }
365 static struct sysrq_key_op sysrq_moom_op = {
366 .handler = sysrq_handle_moom,
367 .help_msg = "memory-full-oom-kill(f)",
368 .action_msg = "Manual OOM execution",
369 .enable_mask = SYSRQ_ENABLE_SIGNAL,
370 };
371
372 #ifdef CONFIG_BLOCK
373 static void sysrq_handle_thaw(int key)
374 {
375 emergency_thaw_all();
376 }
377 static struct sysrq_key_op sysrq_thaw_op = {
378 .handler = sysrq_handle_thaw,
379 .help_msg = "thaw-filesystems(j)",
380 .action_msg = "Emergency Thaw of all frozen filesystems",
381 .enable_mask = SYSRQ_ENABLE_SIGNAL,
382 };
383 #endif
384
385 static void sysrq_handle_kill(int key)
386 {
387 send_sig_all(SIGKILL);
388 console_loglevel = 8;
389 }
390 static struct sysrq_key_op sysrq_kill_op = {
391 .handler = sysrq_handle_kill,
392 .help_msg = "kill-all-tasks(i)",
393 .action_msg = "Kill All Tasks",
394 .enable_mask = SYSRQ_ENABLE_SIGNAL,
395 };
396
397 static void sysrq_handle_unrt(int key)
398 {
399 normalize_rt_tasks();
400 }
401 static struct sysrq_key_op sysrq_unrt_op = {
402 .handler = sysrq_handle_unrt,
403 .help_msg = "nice-all-RT-tasks(n)",
404 .action_msg = "Nice All RT Tasks",
405 .enable_mask = SYSRQ_ENABLE_RTNICE,
406 };
407
408 /* Key Operations table and lock */
409 static DEFINE_SPINLOCK(sysrq_key_table_lock);
410
411 static struct sysrq_key_op *sysrq_key_table[36] = {
412 &sysrq_loglevel_op, /* 0 */
413 &sysrq_loglevel_op, /* 1 */
414 &sysrq_loglevel_op, /* 2 */
415 &sysrq_loglevel_op, /* 3 */
416 &sysrq_loglevel_op, /* 4 */
417 &sysrq_loglevel_op, /* 5 */
418 &sysrq_loglevel_op, /* 6 */
419 &sysrq_loglevel_op, /* 7 */
420 &sysrq_loglevel_op, /* 8 */
421 &sysrq_loglevel_op, /* 9 */
422
423 /*
424 * a: Don't use for system provided sysrqs, it is handled specially on
425 * sparc and will never arrive.
426 */
427 NULL, /* a */
428 &sysrq_reboot_op, /* b */
429 &sysrq_crash_op, /* c & ibm_emac driver debug */
430 &sysrq_showlocks_op, /* d */
431 &sysrq_term_op, /* e */
432 &sysrq_moom_op, /* f */
433 /* g: May be registered for the kernel debugger */
434 NULL, /* g */
435 NULL, /* h - reserved for help */
436 &sysrq_kill_op, /* i */
437 #ifdef CONFIG_BLOCK
438 &sysrq_thaw_op, /* j */
439 #else
440 NULL, /* j */
441 #endif
442 &sysrq_SAK_op, /* k */
443 #ifdef CONFIG_SMP
444 &sysrq_showallcpus_op, /* l */
445 #else
446 NULL, /* l */
447 #endif
448 &sysrq_showmem_op, /* m */
449 &sysrq_unrt_op, /* n */
450 /* o: This will often be registered as 'Off' at init time */
451 NULL, /* o */
452 &sysrq_showregs_op, /* p */
453 &sysrq_show_timers_op, /* q */
454 &sysrq_unraw_op, /* r */
455 &sysrq_sync_op, /* s */
456 &sysrq_showstate_op, /* t */
457 &sysrq_mountro_op, /* u */
458 /* v: May be registered for frame buffer console restore */
459 NULL, /* v */
460 &sysrq_showstate_blocked_op, /* w */
461 /* x: May be registered on ppc/powerpc for xmon */
462 /* x: May be registered on sparc64 for global PMU dump */
463 NULL, /* x */
464 /* y: May be registered on sparc64 for global register dump */
465 NULL, /* y */
466 &sysrq_ftrace_dump_op, /* z */
467 };
468
469 /* key2index calculation, -1 on invalid index */
470 static int sysrq_key_table_key2index(int key)
471 {
472 int retval;
473
474 if ((key >= '0') && (key <= '9'))
475 retval = key - '0';
476 else if ((key >= 'a') && (key <= 'z'))
477 retval = key + 10 - 'a';
478 else
479 retval = -1;
480 return retval;
481 }
482
483 /*
484 * get and put functions for the table, exposed to modules.
485 */
486 struct sysrq_key_op *__sysrq_get_key_op(int key)
487 {
488 struct sysrq_key_op *op_p = NULL;
489 int i;
490
491 i = sysrq_key_table_key2index(key);
492 if (i != -1)
493 op_p = sysrq_key_table[i];
494
495 return op_p;
496 }
497
498 static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
499 {
500 int i = sysrq_key_table_key2index(key);
501
502 if (i != -1)
503 sysrq_key_table[i] = op_p;
504 }
505
506 void __handle_sysrq(int key, bool check_mask)
507 {
508 struct sysrq_key_op *op_p;
509 int orig_log_level;
510 int i;
511 unsigned long flags;
512
513 spin_lock_irqsave(&sysrq_key_table_lock, flags);
514 /*
515 * Raise the apparent loglevel to maximum so that the sysrq header
516 * is shown to provide the user with positive feedback. We do not
517 * simply emit this at KERN_EMERG as that would change message
518 * routing in the consumers of /proc/kmsg.
519 */
520 orig_log_level = console_loglevel;
521 console_loglevel = 7;
522 printk(KERN_INFO "SysRq : ");
523
524 op_p = __sysrq_get_key_op(key);
525 if (op_p) {
526 /*
527 * Should we check for enabled operations (/proc/sysrq-trigger
528 * should not) and is the invoked operation enabled?
529 */
530 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
531 printk("%s\n", op_p->action_msg);
532 console_loglevel = orig_log_level;
533 op_p->handler(key);
534 } else {
535 printk("This sysrq operation is disabled.\n");
536 }
537 } else {
538 printk("HELP : ");
539 /* Only print the help msg once per handler */
540 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
541 if (sysrq_key_table[i]) {
542 int j;
543
544 for (j = 0; sysrq_key_table[i] !=
545 sysrq_key_table[j]; j++)
546 ;
547 if (j != i)
548 continue;
549 printk("%s ", sysrq_key_table[i]->help_msg);
550 }
551 }
552 printk("\n");
553 console_loglevel = orig_log_level;
554 }
555 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
556 }
557
558 void handle_sysrq(int key)
559 {
560 if (sysrq_on())
561 __handle_sysrq(key, true);
562 }
563 EXPORT_SYMBOL(handle_sysrq);
564
565 #ifdef CONFIG_INPUT
566
567 /* Simple translation table for the SysRq keys */
568 static const unsigned char sysrq_xlate[KEY_CNT] =
569 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */
570 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */
571 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */
572 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */
573 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */
574 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
575 "\r\000/"; /* 0x60 - 0x6f */
576
577 struct sysrq_state {
578 struct input_handle handle;
579 struct work_struct reinject_work;
580 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
581 unsigned int alt;
582 unsigned int alt_use;
583 bool active;
584 bool need_reinject;
585 bool reinjecting;
586
587 /* reset sequence handling */
588 bool reset_canceled;
589 unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)];
590 int reset_seq_len;
591 int reset_seq_cnt;
592 int reset_seq_version;
593 struct timer_list keyreset_timer;
594 };
595
596 #define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */
597 static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX];
598 static unsigned int sysrq_reset_seq_len;
599 static unsigned int sysrq_reset_seq_version = 1;
600
601 static void sysrq_parse_reset_sequence(struct sysrq_state *state)
602 {
603 int i;
604 unsigned short key;
605
606 state->reset_seq_cnt = 0;
607
608 for (i = 0; i < sysrq_reset_seq_len; i++) {
609 key = sysrq_reset_seq[i];
610
611 if (key == KEY_RESERVED || key > KEY_MAX)
612 break;
613
614 __set_bit(key, state->reset_keybit);
615 state->reset_seq_len++;
616
617 if (test_bit(key, state->key_down))
618 state->reset_seq_cnt++;
619 }
620
621 /* Disable reset until old keys are not released */
622 state->reset_canceled = state->reset_seq_cnt != 0;
623
624 state->reset_seq_version = sysrq_reset_seq_version;
625 }
626
627 static void sysrq_do_reset(unsigned long dummy)
628 {
629 __handle_sysrq(sysrq_xlate[KEY_B], false);
630 }
631
632 static void sysrq_handle_reset_request(struct sysrq_state *state)
633 {
634 if (sysrq_reset_downtime_ms)
635 mod_timer(&state->keyreset_timer,
636 jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms));
637 else
638 sysrq_do_reset(0);
639 }
640
641 static void sysrq_detect_reset_sequence(struct sysrq_state *state,
642 unsigned int code, int value)
643 {
644 if (!test_bit(code, state->reset_keybit)) {
645 /*
646 * Pressing any key _not_ in reset sequence cancels
647 * the reset sequence. Also cancelling the timer in
648 * case additional keys were pressed after a reset
649 * has been requested.
650 */
651 if (value && state->reset_seq_cnt) {
652 state->reset_canceled = true;
653 del_timer(&state->keyreset_timer);
654 }
655 } else if (value == 0) {
656 /*
657 * Key release - all keys in the reset sequence need
658 * to be pressed and held for the reset timeout
659 * to hold.
660 */
661 del_timer(&state->keyreset_timer);
662
663 if (--state->reset_seq_cnt == 0)
664 state->reset_canceled = false;
665 } else if (value == 1) {
666 /* key press, not autorepeat */
667 if (++state->reset_seq_cnt == state->reset_seq_len &&
668 !state->reset_canceled) {
669 sysrq_handle_reset_request(state);
670 }
671 }
672 }
673
674 static void sysrq_reinject_alt_sysrq(struct work_struct *work)
675 {
676 struct sysrq_state *sysrq =
677 container_of(work, struct sysrq_state, reinject_work);
678 struct input_handle *handle = &sysrq->handle;
679 unsigned int alt_code = sysrq->alt_use;
680
681 if (sysrq->need_reinject) {
682 /* we do not want the assignment to be reordered */
683 sysrq->reinjecting = true;
684 mb();
685
686 /* Simulate press and release of Alt + SysRq */
687 input_inject_event(handle, EV_KEY, alt_code, 1);
688 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
689 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
690
691 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
692 input_inject_event(handle, EV_KEY, alt_code, 0);
693 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
694
695 mb();
696 sysrq->reinjecting = false;
697 }
698 }
699
700 static bool sysrq_handle_keypress(struct sysrq_state *sysrq,
701 unsigned int code, int value)
702 {
703 bool was_active = sysrq->active;
704 bool suppress;
705
706 switch (code) {
707
708 case KEY_LEFTALT:
709 case KEY_RIGHTALT:
710 if (!value) {
711 /* One of ALTs is being released */
712 if (sysrq->active && code == sysrq->alt_use)
713 sysrq->active = false;
714
715 sysrq->alt = KEY_RESERVED;
716
717 } else if (value != 2) {
718 sysrq->alt = code;
719 sysrq->need_reinject = false;
720 }
721 break;
722
723 case KEY_SYSRQ:
724 if (value == 1 && sysrq->alt != KEY_RESERVED) {
725 sysrq->active = true;
726 sysrq->alt_use = sysrq->alt;
727 /*
728 * If nothing else will be pressed we'll need
729 * to re-inject Alt-SysRq keysroke.
730 */
731 sysrq->need_reinject = true;
732 }
733
734 /*
735 * Pretend that sysrq was never pressed at all. This
736 * is needed to properly handle KGDB which will try
737 * to release all keys after exiting debugger. If we
738 * do not clear key bit it KGDB will end up sending
739 * release events for Alt and SysRq, potentially
740 * triggering print screen function.
741 */
742 if (sysrq->active)
743 clear_bit(KEY_SYSRQ, sysrq->handle.dev->key);
744
745 break;
746
747 default:
748 if (sysrq->active && value && value != 2) {
749 sysrq->need_reinject = false;
750 __handle_sysrq(sysrq_xlate[code], true);
751 }
752 break;
753 }
754
755 suppress = sysrq->active;
756
757 if (!sysrq->active) {
758
759 /*
760 * See if reset sequence has changed since the last time.
761 */
762 if (sysrq->reset_seq_version != sysrq_reset_seq_version)
763 sysrq_parse_reset_sequence(sysrq);
764
765 /*
766 * If we are not suppressing key presses keep track of
767 * keyboard state so we can release keys that have been
768 * pressed before entering SysRq mode.
769 */
770 if (value)
771 set_bit(code, sysrq->key_down);
772 else
773 clear_bit(code, sysrq->key_down);
774
775 if (was_active)
776 schedule_work(&sysrq->reinject_work);
777
778 /* Check for reset sequence */
779 sysrq_detect_reset_sequence(sysrq, code, value);
780
781 } else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) {
782 /*
783 * Pass on release events for keys that was pressed before
784 * entering SysRq mode.
785 */
786 suppress = false;
787 }
788
789 return suppress;
790 }
791
792 static bool sysrq_filter(struct input_handle *handle,
793 unsigned int type, unsigned int code, int value)
794 {
795 struct sysrq_state *sysrq = handle->private;
796 bool suppress;
797
798 /*
799 * Do not filter anything if we are in the process of re-injecting
800 * Alt+SysRq combination.
801 */
802 if (sysrq->reinjecting)
803 return false;
804
805 switch (type) {
806
807 case EV_SYN:
808 suppress = false;
809 break;
810
811 case EV_KEY:
812 suppress = sysrq_handle_keypress(sysrq, code, value);
813 break;
814
815 default:
816 suppress = sysrq->active;
817 break;
818 }
819
820 return suppress;
821 }
822
823 static int sysrq_connect(struct input_handler *handler,
824 struct input_dev *dev,
825 const struct input_device_id *id)
826 {
827 struct sysrq_state *sysrq;
828 int error;
829
830 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);
831 if (!sysrq)
832 return -ENOMEM;
833
834 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
835
836 sysrq->handle.dev = dev;
837 sysrq->handle.handler = handler;
838 sysrq->handle.name = "sysrq";
839 sysrq->handle.private = sysrq;
840 setup_timer(&sysrq->keyreset_timer, sysrq_do_reset, 0);
841
842 error = input_register_handle(&sysrq->handle);
843 if (error) {
844 pr_err("Failed to register input sysrq handler, error %d\n",
845 error);
846 goto err_free;
847 }
848
849 error = input_open_device(&sysrq->handle);
850 if (error) {
851 pr_err("Failed to open input device, error %d\n", error);
852 goto err_unregister;
853 }
854
855 return 0;
856
857 err_unregister:
858 input_unregister_handle(&sysrq->handle);
859 err_free:
860 kfree(sysrq);
861 return error;
862 }
863
864 static void sysrq_disconnect(struct input_handle *handle)
865 {
866 struct sysrq_state *sysrq = handle->private;
867
868 input_close_device(handle);
869 cancel_work_sync(&sysrq->reinject_work);
870 del_timer_sync(&sysrq->keyreset_timer);
871 input_unregister_handle(handle);
872 kfree(sysrq);
873 }
874
875 /*
876 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all
877 * keyboards have SysRq key predefined and so user may add it to keymap
878 * later, but we expect all such keyboards to have left alt.
879 */
880 static const struct input_device_id sysrq_ids[] = {
881 {
882 .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
883 INPUT_DEVICE_ID_MATCH_KEYBIT,
884 .evbit = { [BIT_WORD(EV_KEY)] = BIT_MASK(EV_KEY) },
885 .keybit = { [BIT_WORD(KEY_LEFTALT)] = BIT_MASK(KEY_LEFTALT) },
886 },
887 { },
888 };
889
890 static struct input_handler sysrq_handler = {
891 .filter = sysrq_filter,
892 .connect = sysrq_connect,
893 .disconnect = sysrq_disconnect,
894 .name = "sysrq",
895 .id_table = sysrq_ids,
896 };
897
898 static bool sysrq_handler_registered;
899
900 static inline void sysrq_register_handler(void)
901 {
902 unsigned short key;
903 int error;
904 int i;
905
906 for (i = 0; i < ARRAY_SIZE(sysrq_reset_seq); i++) {
907 key = platform_sysrq_reset_seq[i];
908 if (key == KEY_RESERVED || key > KEY_MAX)
909 break;
910
911 sysrq_reset_seq[sysrq_reset_seq_len++] = key;
912 }
913
914 error = input_register_handler(&sysrq_handler);
915 if (error)
916 pr_err("Failed to register input handler, error %d", error);
917 else
918 sysrq_handler_registered = true;
919 }
920
921 static inline void sysrq_unregister_handler(void)
922 {
923 if (sysrq_handler_registered) {
924 input_unregister_handler(&sysrq_handler);
925 sysrq_handler_registered = false;
926 }
927 }
928
929 static int sysrq_reset_seq_param_set(const char *buffer,
930 const struct kernel_param *kp)
931 {
932 unsigned long val;
933 int error;
934
935 error = strict_strtoul(buffer, 0, &val);
936 if (error < 0)
937 return error;
938
939 if (val > KEY_MAX)
940 return -EINVAL;
941
942 *((unsigned short *)kp->arg) = val;
943 sysrq_reset_seq_version++;
944
945 return 0;
946 }
947
948 static struct kernel_param_ops param_ops_sysrq_reset_seq = {
949 .get = param_get_ushort,
950 .set = sysrq_reset_seq_param_set,
951 };
952
953 #define param_check_sysrq_reset_seq(name, p) \
954 __param_check(name, p, unsigned short)
955
956 module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq,
957 &sysrq_reset_seq_len, 0644);
958
959 module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644);
960
961 #else
962
963 static inline void sysrq_register_handler(void)
964 {
965 }
966
967 static inline void sysrq_unregister_handler(void)
968 {
969 }
970
971 #endif /* CONFIG_INPUT */
972
973 int sysrq_toggle_support(int enable_mask)
974 {
975 bool was_enabled = sysrq_on();
976
977 sysrq_enabled = enable_mask;
978
979 if (was_enabled != sysrq_on()) {
980 if (sysrq_on())
981 sysrq_register_handler();
982 else
983 sysrq_unregister_handler();
984 }
985
986 return 0;
987 }
988
989 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
990 struct sysrq_key_op *remove_op_p)
991 {
992 int retval;
993 unsigned long flags;
994
995 spin_lock_irqsave(&sysrq_key_table_lock, flags);
996 if (__sysrq_get_key_op(key) == remove_op_p) {
997 __sysrq_put_key_op(key, insert_op_p);
998 retval = 0;
999 } else {
1000 retval = -1;
1001 }
1002 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
1003 return retval;
1004 }
1005
1006 int register_sysrq_key(int key, struct sysrq_key_op *op_p)
1007 {
1008 return __sysrq_swap_key_ops(key, op_p, NULL);
1009 }
1010 EXPORT_SYMBOL(register_sysrq_key);
1011
1012 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
1013 {
1014 return __sysrq_swap_key_ops(key, NULL, op_p);
1015 }
1016 EXPORT_SYMBOL(unregister_sysrq_key);
1017
1018 #ifdef CONFIG_PROC_FS
1019 /*
1020 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
1021 */
1022 static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
1023 size_t count, loff_t *ppos)
1024 {
1025 if (count) {
1026 char c;
1027
1028 if (get_user(c, buf))
1029 return -EFAULT;
1030 __handle_sysrq(c, false);
1031 }
1032
1033 return count;
1034 }
1035
1036 static const struct file_operations proc_sysrq_trigger_operations = {
1037 .write = write_sysrq_trigger,
1038 .llseek = noop_llseek,
1039 };
1040
1041 static void sysrq_init_procfs(void)
1042 {
1043 if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
1044 &proc_sysrq_trigger_operations))
1045 pr_err("Failed to register proc interface\n");
1046 }
1047
1048 #else
1049
1050 static inline void sysrq_init_procfs(void)
1051 {
1052 }
1053
1054 #endif /* CONFIG_PROC_FS */
1055
1056 static int __init sysrq_init(void)
1057 {
1058 sysrq_init_procfs();
1059
1060 if (sysrq_on())
1061 sysrq_register_handler();
1062
1063 return 0;
1064 }
1065 module_init(sysrq_init);