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15#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
16
17#include <linux/sched/signal.h>
18#include <linux/sched/rt.h>
19#include <linux/sched/debug.h>
20#include <linux/sched/task.h>
21#include <linux/interrupt.h>
22#include <linux/mm.h>
23#include <linux/fs.h>
24#include <linux/mount.h>
25#include <linux/kdev_t.h>
26#include <linux/major.h>
27#include <linux/reboot.h>
28#include <linux/sysrq.h>
29#include <linux/kbd_kern.h>
30#include <linux/proc_fs.h>
31#include <linux/nmi.h>
32#include <linux/quotaops.h>
33#include <linux/perf_event.h>
34#include <linux/kernel.h>
35#include <linux/module.h>
36#include <linux/suspend.h>
37#include <linux/writeback.h>
38#include <linux/swap.h>
39#include <linux/spinlock.h>
40#include <linux/vt_kern.h>
41#include <linux/workqueue.h>
42#include <linux/hrtimer.h>
43#include <linux/oom.h>
44#include <linux/slab.h>
45#include <linux/input.h>
46#include <linux/uaccess.h>
47#include <linux/moduleparam.h>
48#include <linux/jiffies.h>
49#include <linux/syscalls.h>
50#include <linux/of.h>
51#include <linux/rcupdate.h>
52
53#include <asm/ptrace.h>
54#include <asm/irq_regs.h>
55
56
57static int __read_mostly sysrq_enabled = CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE;
58static bool __read_mostly sysrq_always_enabled;
59
60static bool sysrq_on(void)
61{
62 return sysrq_enabled || sysrq_always_enabled;
63}
64
65
66
67
68static bool sysrq_on_mask(int mask)
69{
70 return sysrq_always_enabled ||
71 sysrq_enabled == 1 ||
72 (sysrq_enabled & mask);
73}
74
75static int __init sysrq_always_enabled_setup(char *str)
76{
77 sysrq_always_enabled = true;
78 pr_info("sysrq always enabled.\n");
79
80 return 1;
81}
82
83__setup("sysrq_always_enabled", sysrq_always_enabled_setup);
84
85
86static void sysrq_handle_loglevel(int key)
87{
88 int i;
89
90 i = key - '0';
91 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
92 pr_info("Loglevel set to %d\n", i);
93 console_loglevel = i;
94}
95static struct sysrq_key_op sysrq_loglevel_op = {
96 .handler = sysrq_handle_loglevel,
97 .help_msg = "loglevel(0-9)",
98 .action_msg = "Changing Loglevel",
99 .enable_mask = SYSRQ_ENABLE_LOG,
100};
101
102#ifdef CONFIG_VT
103static void sysrq_handle_SAK(int key)
104{
105 struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
106 schedule_work(SAK_work);
107}
108static struct sysrq_key_op sysrq_SAK_op = {
109 .handler = sysrq_handle_SAK,
110 .help_msg = "sak(k)",
111 .action_msg = "SAK",
112 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
113};
114#else
115#define sysrq_SAK_op (*(struct sysrq_key_op *)NULL)
116#endif
117
118#ifdef CONFIG_VT
119static void sysrq_handle_unraw(int key)
120{
121 vt_reset_unicode(fg_console);
122}
123
124static struct sysrq_key_op sysrq_unraw_op = {
125 .handler = sysrq_handle_unraw,
126 .help_msg = "unraw(r)",
127 .action_msg = "Keyboard mode set to system default",
128 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
129};
130#else
131#define sysrq_unraw_op (*(struct sysrq_key_op *)NULL)
132#endif
133
134static void sysrq_handle_crash(int key)
135{
136 char *killer = NULL;
137
138
139
140
141
142
143 rcu_read_unlock();
144 panic_on_oops = 1;
145 wmb();
146 *killer = 1;
147}
148static struct sysrq_key_op sysrq_crash_op = {
149 .handler = sysrq_handle_crash,
150 .help_msg = "crash(c)",
151 .action_msg = "Trigger a crash",
152 .enable_mask = SYSRQ_ENABLE_DUMP,
153};
154
155static void sysrq_handle_reboot(int key)
156{
157 lockdep_off();
158 local_irq_enable();
159 emergency_restart();
160}
161static struct sysrq_key_op sysrq_reboot_op = {
162 .handler = sysrq_handle_reboot,
163 .help_msg = "reboot(b)",
164 .action_msg = "Resetting",
165 .enable_mask = SYSRQ_ENABLE_BOOT,
166};
167
168static void sysrq_handle_sync(int key)
169{
170 emergency_sync();
171}
172static struct sysrq_key_op sysrq_sync_op = {
173 .handler = sysrq_handle_sync,
174 .help_msg = "sync(s)",
175 .action_msg = "Emergency Sync",
176 .enable_mask = SYSRQ_ENABLE_SYNC,
177};
178
179static void sysrq_handle_show_timers(int key)
180{
181 sysrq_timer_list_show();
182}
183
184static struct sysrq_key_op sysrq_show_timers_op = {
185 .handler = sysrq_handle_show_timers,
186 .help_msg = "show-all-timers(q)",
187 .action_msg = "Show clockevent devices & pending hrtimers (no others)",
188};
189
190static void sysrq_handle_mountro(int key)
191{
192 emergency_remount();
193}
194static struct sysrq_key_op sysrq_mountro_op = {
195 .handler = sysrq_handle_mountro,
196 .help_msg = "unmount(u)",
197 .action_msg = "Emergency Remount R/O",
198 .enable_mask = SYSRQ_ENABLE_REMOUNT,
199};
200
201#ifdef CONFIG_LOCKDEP
202static void sysrq_handle_showlocks(int key)
203{
204 debug_show_all_locks();
205}
206
207static struct sysrq_key_op sysrq_showlocks_op = {
208 .handler = sysrq_handle_showlocks,
209 .help_msg = "show-all-locks(d)",
210 .action_msg = "Show Locks Held",
211};
212#else
213#define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL)
214#endif
215
216#ifdef CONFIG_SMP
217static DEFINE_SPINLOCK(show_lock);
218
219static void showacpu(void *dummy)
220{
221 unsigned long flags;
222
223
224 if (idle_cpu(smp_processor_id()))
225 return;
226
227 spin_lock_irqsave(&show_lock, flags);
228 pr_info("CPU%d:\n", smp_processor_id());
229 show_stack(NULL, NULL);
230 spin_unlock_irqrestore(&show_lock, flags);
231}
232
233static void sysrq_showregs_othercpus(struct work_struct *dummy)
234{
235 smp_call_function(showacpu, NULL, 0);
236}
237
238static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
239
240static void sysrq_handle_showallcpus(int key)
241{
242
243
244
245
246
247 if (!trigger_all_cpu_backtrace()) {
248 struct pt_regs *regs = get_irq_regs();
249
250 if (regs) {
251 pr_info("CPU%d:\n", smp_processor_id());
252 show_regs(regs);
253 }
254 schedule_work(&sysrq_showallcpus);
255 }
256}
257
258static struct sysrq_key_op sysrq_showallcpus_op = {
259 .handler = sysrq_handle_showallcpus,
260 .help_msg = "show-backtrace-all-active-cpus(l)",
261 .action_msg = "Show backtrace of all active CPUs",
262 .enable_mask = SYSRQ_ENABLE_DUMP,
263};
264#endif
265
266static void sysrq_handle_showregs(int key)
267{
268 struct pt_regs *regs = get_irq_regs();
269 if (regs)
270 show_regs(regs);
271 perf_event_print_debug();
272}
273static struct sysrq_key_op sysrq_showregs_op = {
274 .handler = sysrq_handle_showregs,
275 .help_msg = "show-registers(p)",
276 .action_msg = "Show Regs",
277 .enable_mask = SYSRQ_ENABLE_DUMP,
278};
279
280static void sysrq_handle_showstate(int key)
281{
282 show_state();
283 show_workqueue_state();
284}
285static struct sysrq_key_op sysrq_showstate_op = {
286 .handler = sysrq_handle_showstate,
287 .help_msg = "show-task-states(t)",
288 .action_msg = "Show State",
289 .enable_mask = SYSRQ_ENABLE_DUMP,
290};
291
292static void sysrq_handle_showstate_blocked(int key)
293{
294 show_state_filter(TASK_UNINTERRUPTIBLE);
295}
296static struct sysrq_key_op sysrq_showstate_blocked_op = {
297 .handler = sysrq_handle_showstate_blocked,
298 .help_msg = "show-blocked-tasks(w)",
299 .action_msg = "Show Blocked State",
300 .enable_mask = SYSRQ_ENABLE_DUMP,
301};
302
303#ifdef CONFIG_TRACING
304#include <linux/ftrace.h>
305
306static void sysrq_ftrace_dump(int key)
307{
308 ftrace_dump(DUMP_ALL);
309}
310static struct sysrq_key_op sysrq_ftrace_dump_op = {
311 .handler = sysrq_ftrace_dump,
312 .help_msg = "dump-ftrace-buffer(z)",
313 .action_msg = "Dump ftrace buffer",
314 .enable_mask = SYSRQ_ENABLE_DUMP,
315};
316#else
317#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
318#endif
319
320static void sysrq_handle_showmem(int key)
321{
322 show_mem(0, NULL);
323}
324static struct sysrq_key_op sysrq_showmem_op = {
325 .handler = sysrq_handle_showmem,
326 .help_msg = "show-memory-usage(m)",
327 .action_msg = "Show Memory",
328 .enable_mask = SYSRQ_ENABLE_DUMP,
329};
330
331
332
333
334static void send_sig_all(int sig)
335{
336 struct task_struct *p;
337
338 read_lock(&tasklist_lock);
339 for_each_process(p) {
340 if (p->flags & PF_KTHREAD)
341 continue;
342 if (is_global_init(p))
343 continue;
344
345 do_send_sig_info(sig, SEND_SIG_FORCED, p, true);
346 }
347 read_unlock(&tasklist_lock);
348}
349
350static void sysrq_handle_term(int key)
351{
352 send_sig_all(SIGTERM);
353 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
354}
355static struct sysrq_key_op sysrq_term_op = {
356 .handler = sysrq_handle_term,
357 .help_msg = "terminate-all-tasks(e)",
358 .action_msg = "Terminate All Tasks",
359 .enable_mask = SYSRQ_ENABLE_SIGNAL,
360};
361
362static void moom_callback(struct work_struct *ignored)
363{
364 const gfp_t gfp_mask = GFP_KERNEL;
365 struct oom_control oc = {
366 .zonelist = node_zonelist(first_memory_node, gfp_mask),
367 .nodemask = NULL,
368 .memcg = NULL,
369 .gfp_mask = gfp_mask,
370 .order = -1,
371 };
372
373 mutex_lock(&oom_lock);
374 if (!out_of_memory(&oc))
375 pr_info("OOM request ignored. No task eligible\n");
376 mutex_unlock(&oom_lock);
377}
378
379static DECLARE_WORK(moom_work, moom_callback);
380
381static void sysrq_handle_moom(int key)
382{
383 schedule_work(&moom_work);
384}
385static struct sysrq_key_op sysrq_moom_op = {
386 .handler = sysrq_handle_moom,
387 .help_msg = "memory-full-oom-kill(f)",
388 .action_msg = "Manual OOM execution",
389 .enable_mask = SYSRQ_ENABLE_SIGNAL,
390};
391
392#ifdef CONFIG_BLOCK
393static void sysrq_handle_thaw(int key)
394{
395 emergency_thaw_all();
396}
397static struct sysrq_key_op sysrq_thaw_op = {
398 .handler = sysrq_handle_thaw,
399 .help_msg = "thaw-filesystems(j)",
400 .action_msg = "Emergency Thaw of all frozen filesystems",
401 .enable_mask = SYSRQ_ENABLE_SIGNAL,
402};
403#endif
404
405static void sysrq_handle_kill(int key)
406{
407 send_sig_all(SIGKILL);
408 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
409}
410static struct sysrq_key_op sysrq_kill_op = {
411 .handler = sysrq_handle_kill,
412 .help_msg = "kill-all-tasks(i)",
413 .action_msg = "Kill All Tasks",
414 .enable_mask = SYSRQ_ENABLE_SIGNAL,
415};
416
417static void sysrq_handle_unrt(int key)
418{
419 normalize_rt_tasks();
420}
421static struct sysrq_key_op sysrq_unrt_op = {
422 .handler = sysrq_handle_unrt,
423 .help_msg = "nice-all-RT-tasks(n)",
424 .action_msg = "Nice All RT Tasks",
425 .enable_mask = SYSRQ_ENABLE_RTNICE,
426};
427
428
429static DEFINE_SPINLOCK(sysrq_key_table_lock);
430
431static struct sysrq_key_op *sysrq_key_table[36] = {
432 &sysrq_loglevel_op,
433 &sysrq_loglevel_op,
434 &sysrq_loglevel_op,
435 &sysrq_loglevel_op,
436 &sysrq_loglevel_op,
437 &sysrq_loglevel_op,
438 &sysrq_loglevel_op,
439 &sysrq_loglevel_op,
440 &sysrq_loglevel_op,
441 &sysrq_loglevel_op,
442
443
444
445
446
447 NULL,
448 &sysrq_reboot_op,
449 &sysrq_crash_op,
450 &sysrq_showlocks_op,
451 &sysrq_term_op,
452 &sysrq_moom_op,
453
454 NULL,
455 NULL,
456 &sysrq_kill_op,
457#ifdef CONFIG_BLOCK
458 &sysrq_thaw_op,
459#else
460 NULL,
461#endif
462 &sysrq_SAK_op,
463#ifdef CONFIG_SMP
464 &sysrq_showallcpus_op,
465#else
466 NULL,
467#endif
468 &sysrq_showmem_op,
469 &sysrq_unrt_op,
470
471 NULL,
472 &sysrq_showregs_op,
473 &sysrq_show_timers_op,
474 &sysrq_unraw_op,
475 &sysrq_sync_op,
476 &sysrq_showstate_op,
477 &sysrq_mountro_op,
478
479 NULL,
480 &sysrq_showstate_blocked_op,
481
482
483
484 NULL,
485
486 NULL,
487 &sysrq_ftrace_dump_op,
488};
489
490
491static int sysrq_key_table_key2index(int key)
492{
493 int retval;
494
495 if ((key >= '0') && (key <= '9'))
496 retval = key - '0';
497 else if ((key >= 'a') && (key <= 'z'))
498 retval = key + 10 - 'a';
499 else
500 retval = -1;
501 return retval;
502}
503
504
505
506
507struct sysrq_key_op *__sysrq_get_key_op(int key)
508{
509 struct sysrq_key_op *op_p = NULL;
510 int i;
511
512 i = sysrq_key_table_key2index(key);
513 if (i != -1)
514 op_p = sysrq_key_table[i];
515
516 return op_p;
517}
518
519static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
520{
521 int i = sysrq_key_table_key2index(key);
522
523 if (i != -1)
524 sysrq_key_table[i] = op_p;
525}
526
527void __handle_sysrq(int key, bool check_mask)
528{
529 struct sysrq_key_op *op_p;
530 int orig_log_level;
531 int i;
532
533 rcu_sysrq_start();
534 rcu_read_lock();
535
536
537
538
539
540
541 orig_log_level = console_loglevel;
542 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
543 pr_info("SysRq : ");
544
545 op_p = __sysrq_get_key_op(key);
546 if (op_p) {
547
548
549
550
551 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
552 pr_cont("%s\n", op_p->action_msg);
553 console_loglevel = orig_log_level;
554 op_p->handler(key);
555 } else {
556 pr_cont("This sysrq operation is disabled.\n");
557 }
558 } else {
559 pr_cont("HELP : ");
560
561 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
562 if (sysrq_key_table[i]) {
563 int j;
564
565 for (j = 0; sysrq_key_table[i] !=
566 sysrq_key_table[j]; j++)
567 ;
568 if (j != i)
569 continue;
570 pr_cont("%s ", sysrq_key_table[i]->help_msg);
571 }
572 }
573 pr_cont("\n");
574 console_loglevel = orig_log_level;
575 }
576 rcu_read_unlock();
577 rcu_sysrq_end();
578}
579
580void handle_sysrq(int key)
581{
582 if (sysrq_on())
583 __handle_sysrq(key, true);
584}
585EXPORT_SYMBOL(handle_sysrq);
586
587#ifdef CONFIG_INPUT
588static int sysrq_reset_downtime_ms;
589
590
591static const unsigned char sysrq_xlate[KEY_CNT] =
592 "\000\0331234567890-=\177\t"
593 "qwertyuiop[]\r\000as"
594 "dfghjkl;'`\000\\zxcv"
595 "bnm,./\000*\000 \000\201\202\203\204\205"
596 "\206\207\210\211\212\000\000789-456+1"
597 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000"
598 "\r\000/";
599
600struct sysrq_state {
601 struct input_handle handle;
602 struct work_struct reinject_work;
603 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
604 unsigned int alt;
605 unsigned int alt_use;
606 bool active;
607 bool need_reinject;
608 bool reinjecting;
609
610
611 bool reset_canceled;
612 bool reset_requested;
613 unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)];
614 int reset_seq_len;
615 int reset_seq_cnt;
616 int reset_seq_version;
617 struct timer_list keyreset_timer;
618};
619
620#define SYSRQ_KEY_RESET_MAX 20
621static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX];
622static unsigned int sysrq_reset_seq_len;
623static unsigned int sysrq_reset_seq_version = 1;
624
625static void sysrq_parse_reset_sequence(struct sysrq_state *state)
626{
627 int i;
628 unsigned short key;
629
630 state->reset_seq_cnt = 0;
631
632 for (i = 0; i < sysrq_reset_seq_len; i++) {
633 key = sysrq_reset_seq[i];
634
635 if (key == KEY_RESERVED || key > KEY_MAX)
636 break;
637
638 __set_bit(key, state->reset_keybit);
639 state->reset_seq_len++;
640
641 if (test_bit(key, state->key_down))
642 state->reset_seq_cnt++;
643 }
644
645
646 state->reset_canceled = state->reset_seq_cnt != 0;
647
648 state->reset_seq_version = sysrq_reset_seq_version;
649}
650
651static void sysrq_do_reset(unsigned long _state)
652{
653 struct sysrq_state *state = (struct sysrq_state *) _state;
654
655 state->reset_requested = true;
656
657 sys_sync();
658 kernel_restart(NULL);
659}
660
661static void sysrq_handle_reset_request(struct sysrq_state *state)
662{
663 if (state->reset_requested)
664 __handle_sysrq(sysrq_xlate[KEY_B], false);
665
666 if (sysrq_reset_downtime_ms)
667 mod_timer(&state->keyreset_timer,
668 jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms));
669 else
670 sysrq_do_reset((unsigned long)state);
671}
672
673static void sysrq_detect_reset_sequence(struct sysrq_state *state,
674 unsigned int code, int value)
675{
676 if (!test_bit(code, state->reset_keybit)) {
677
678
679
680
681
682
683 if (value && state->reset_seq_cnt) {
684 state->reset_canceled = true;
685 del_timer(&state->keyreset_timer);
686 }
687 } else if (value == 0) {
688
689
690
691
692
693 del_timer(&state->keyreset_timer);
694
695 if (--state->reset_seq_cnt == 0)
696 state->reset_canceled = false;
697 } else if (value == 1) {
698
699 if (++state->reset_seq_cnt == state->reset_seq_len &&
700 !state->reset_canceled) {
701 sysrq_handle_reset_request(state);
702 }
703 }
704}
705
706#ifdef CONFIG_OF
707static void sysrq_of_get_keyreset_config(void)
708{
709 u32 key;
710 struct device_node *np;
711 struct property *prop;
712 const __be32 *p;
713
714 np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq");
715 if (!np) {
716 pr_debug("No sysrq node found");
717 return;
718 }
719
720
721 sysrq_reset_seq_len = 0;
722
723 of_property_for_each_u32(np, "keyset", prop, p, key) {
724 if (key == KEY_RESERVED || key > KEY_MAX ||
725 sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX)
726 break;
727
728 sysrq_reset_seq[sysrq_reset_seq_len++] = (unsigned short)key;
729 }
730
731
732 of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms);
733}
734#else
735static void sysrq_of_get_keyreset_config(void)
736{
737}
738#endif
739
740static void sysrq_reinject_alt_sysrq(struct work_struct *work)
741{
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;
746
747 if (sysrq->need_reinject) {
748
749 sysrq->reinjecting = true;
750 mb();
751
752
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);
756
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);
760
761 mb();
762 sysrq->reinjecting = false;
763 }
764}
765
766static bool sysrq_handle_keypress(struct sysrq_state *sysrq,
767 unsigned int code, int value)
768{
769 bool was_active = sysrq->active;
770 bool suppress;
771
772 switch (code) {
773
774 case KEY_LEFTALT:
775 case KEY_RIGHTALT:
776 if (!value) {
777
778 if (sysrq->active && code == sysrq->alt_use)
779 sysrq->active = false;
780
781 sysrq->alt = KEY_RESERVED;
782
783 } else if (value != 2) {
784 sysrq->alt = code;
785 sysrq->need_reinject = false;
786 }
787 break;
788
789 case KEY_SYSRQ:
790 if (value == 1 && sysrq->alt != KEY_RESERVED) {
791 sysrq->active = true;
792 sysrq->alt_use = sysrq->alt;
793
794
795
796
797 sysrq->need_reinject = true;
798 }
799
800
801
802
803
804
805
806
807
808 if (sysrq->active)
809 clear_bit(KEY_SYSRQ, sysrq->handle.dev->key);
810
811 break;
812
813 default:
814 if (sysrq->active && value && value != 2) {
815 sysrq->need_reinject = false;
816 __handle_sysrq(sysrq_xlate[code], true);
817 }
818 break;
819 }
820
821 suppress = sysrq->active;
822
823 if (!sysrq->active) {
824
825
826
827
828 if (sysrq->reset_seq_version != sysrq_reset_seq_version)
829 sysrq_parse_reset_sequence(sysrq);
830
831
832
833
834
835
836 if (value)
837 set_bit(code, sysrq->key_down);
838 else
839 clear_bit(code, sysrq->key_down);
840
841 if (was_active)
842 schedule_work(&sysrq->reinject_work);
843
844
845 sysrq_detect_reset_sequence(sysrq, code, value);
846
847 } else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) {
848
849
850
851
852 suppress = false;
853 }
854
855 return suppress;
856}
857
858static bool sysrq_filter(struct input_handle *handle,
859 unsigned int type, unsigned int code, int value)
860{
861 struct sysrq_state *sysrq = handle->private;
862 bool suppress;
863
864
865
866
867
868 if (sysrq->reinjecting)
869 return false;
870
871 switch (type) {
872
873 case EV_SYN:
874 suppress = false;
875 break;
876
877 case EV_KEY:
878 suppress = sysrq_handle_keypress(sysrq, code, value);
879 break;
880
881 default:
882 suppress = sysrq->active;
883 break;
884 }
885
886 return suppress;
887}
888
889static int sysrq_connect(struct input_handler *handler,
890 struct input_dev *dev,
891 const struct input_device_id *id)
892{
893 struct sysrq_state *sysrq;
894 int error;
895
896 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);
897 if (!sysrq)
898 return -ENOMEM;
899
900 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
901
902 sysrq->handle.dev = dev;
903 sysrq->handle.handler = handler;
904 sysrq->handle.name = "sysrq";
905 sysrq->handle.private = sysrq;
906 setup_timer(&sysrq->keyreset_timer,
907 sysrq_do_reset, (unsigned long)sysrq);
908
909 error = input_register_handle(&sysrq->handle);
910 if (error) {
911 pr_err("Failed to register input sysrq handler, error %d\n",
912 error);
913 goto err_free;
914 }
915
916 error = input_open_device(&sysrq->handle);
917 if (error) {
918 pr_err("Failed to open input device, error %d\n", error);
919 goto err_unregister;
920 }
921
922 return 0;
923
924 err_unregister:
925 input_unregister_handle(&sysrq->handle);
926 err_free:
927 kfree(sysrq);
928 return error;
929}
930
931static void sysrq_disconnect(struct input_handle *handle)
932{
933 struct sysrq_state *sysrq = handle->private;
934
935 input_close_device(handle);
936 cancel_work_sync(&sysrq->reinject_work);
937 del_timer_sync(&sysrq->keyreset_timer);
938 input_unregister_handle(handle);
939 kfree(sysrq);
940}
941
942
943
944
945
946
947static const struct input_device_id sysrq_ids[] = {
948 {
949 .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
950 INPUT_DEVICE_ID_MATCH_KEYBIT,
951 .evbit = { [BIT_WORD(EV_KEY)] = BIT_MASK(EV_KEY) },
952 .keybit = { [BIT_WORD(KEY_LEFTALT)] = BIT_MASK(KEY_LEFTALT) },
953 },
954 { },
955};
956
957static struct input_handler sysrq_handler = {
958 .filter = sysrq_filter,
959 .connect = sysrq_connect,
960 .disconnect = sysrq_disconnect,
961 .name = "sysrq",
962 .id_table = sysrq_ids,
963};
964
965static bool sysrq_handler_registered;
966
967static inline void sysrq_register_handler(void)
968{
969 int error;
970
971 sysrq_of_get_keyreset_config();
972
973 error = input_register_handler(&sysrq_handler);
974 if (error)
975 pr_err("Failed to register input handler, error %d", error);
976 else
977 sysrq_handler_registered = true;
978}
979
980static inline void sysrq_unregister_handler(void)
981{
982 if (sysrq_handler_registered) {
983 input_unregister_handler(&sysrq_handler);
984 sysrq_handler_registered = false;
985 }
986}
987
988static int sysrq_reset_seq_param_set(const char *buffer,
989 const struct kernel_param *kp)
990{
991 unsigned long val;
992 int error;
993
994 error = kstrtoul(buffer, 0, &val);
995 if (error < 0)
996 return error;
997
998 if (val > KEY_MAX)
999 return -EINVAL;
1000
1001 *((unsigned short *)kp->arg) = val;
1002 sysrq_reset_seq_version++;
1003
1004 return 0;
1005}
1006
1007static const struct kernel_param_ops param_ops_sysrq_reset_seq = {
1008 .get = param_get_ushort,
1009 .set = sysrq_reset_seq_param_set,
1010};
1011
1012#define param_check_sysrq_reset_seq(name, p) \
1013 __param_check(name, p, unsigned short)
1014
1015
1016
1017
1018
1019module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq,
1020 &sysrq_reset_seq_len, 0644);
1021
1022module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644);
1023
1024#else
1025
1026static inline void sysrq_register_handler(void)
1027{
1028}
1029
1030static inline void sysrq_unregister_handler(void)
1031{
1032}
1033
1034#endif
1035
1036int sysrq_toggle_support(int enable_mask)
1037{
1038 bool was_enabled = sysrq_on();
1039
1040 sysrq_enabled = enable_mask;
1041
1042 if (was_enabled != sysrq_on()) {
1043 if (sysrq_on())
1044 sysrq_register_handler();
1045 else
1046 sysrq_unregister_handler();
1047 }
1048
1049 return 0;
1050}
1051
1052static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
1053 struct sysrq_key_op *remove_op_p)
1054{
1055 int retval;
1056
1057 spin_lock(&sysrq_key_table_lock);
1058 if (__sysrq_get_key_op(key) == remove_op_p) {
1059 __sysrq_put_key_op(key, insert_op_p);
1060 retval = 0;
1061 } else {
1062 retval = -1;
1063 }
1064 spin_unlock(&sysrq_key_table_lock);
1065
1066
1067
1068
1069
1070
1071 synchronize_rcu();
1072
1073 return retval;
1074}
1075
1076int register_sysrq_key(int key, struct sysrq_key_op *op_p)
1077{
1078 return __sysrq_swap_key_ops(key, op_p, NULL);
1079}
1080EXPORT_SYMBOL(register_sysrq_key);
1081
1082int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
1083{
1084 return __sysrq_swap_key_ops(key, NULL, op_p);
1085}
1086EXPORT_SYMBOL(unregister_sysrq_key);
1087
1088#ifdef CONFIG_PROC_FS
1089
1090
1091
1092static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
1093 size_t count, loff_t *ppos)
1094{
1095 if (count) {
1096 char c;
1097
1098 if (get_user(c, buf))
1099 return -EFAULT;
1100 __handle_sysrq(c, false);
1101 }
1102
1103 return count;
1104}
1105
1106static const struct file_operations proc_sysrq_trigger_operations = {
1107 .write = write_sysrq_trigger,
1108 .llseek = noop_llseek,
1109};
1110
1111static void sysrq_init_procfs(void)
1112{
1113 if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
1114 &proc_sysrq_trigger_operations))
1115 pr_err("Failed to register proc interface\n");
1116}
1117
1118#else
1119
1120static inline void sysrq_init_procfs(void)
1121{
1122}
1123
1124#endif
1125
1126static int __init sysrq_init(void)
1127{
1128 sysrq_init_procfs();
1129
1130 if (sysrq_on())
1131 sysrq_register_handler();
1132
1133 return 0;
1134}
1135device_initcall(sysrq_init);
1136