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16#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
17
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>
23#include <linux/mm.h>
24#include <linux/fs.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>
51#include <linux/of.h>
52#include <linux/rcupdate.h>
53
54#include <asm/ptrace.h>
55#include <asm/irq_regs.h>
56
57
58static int __read_mostly sysrq_enabled = CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE;
59static bool __read_mostly sysrq_always_enabled;
60
61static bool sysrq_on(void)
62{
63 return sysrq_enabled || sysrq_always_enabled;
64}
65
66
67
68
69static bool sysrq_on_mask(int mask)
70{
71 return sysrq_always_enabled ||
72 sysrq_enabled == 1 ||
73 (sysrq_enabled & mask);
74}
75
76static int __init sysrq_always_enabled_setup(char *str)
77{
78 sysrq_always_enabled = true;
79 pr_info("sysrq always enabled.\n");
80
81 return 1;
82}
83
84__setup("sysrq_always_enabled", sysrq_always_enabled_setup);
85
86
87static void sysrq_handle_loglevel(int key)
88{
89 int i;
90
91 i = key - '0';
92 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
93 pr_info("Loglevel set to %d\n", i);
94 console_loglevel = i;
95}
96static struct sysrq_key_op sysrq_loglevel_op = {
97 .handler = sysrq_handle_loglevel,
98 .help_msg = "loglevel(0-9)",
99 .action_msg = "Changing Loglevel",
100 .enable_mask = SYSRQ_ENABLE_LOG,
101};
102
103#ifdef CONFIG_VT
104static void sysrq_handle_SAK(int key)
105{
106 struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
107 schedule_work(SAK_work);
108}
109static struct sysrq_key_op sysrq_SAK_op = {
110 .handler = sysrq_handle_SAK,
111 .help_msg = "sak(k)",
112 .action_msg = "SAK",
113 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
114};
115#else
116#define sysrq_SAK_op (*(struct sysrq_key_op *)NULL)
117#endif
118
119#ifdef CONFIG_VT
120static void sysrq_handle_unraw(int key)
121{
122 vt_reset_unicode(fg_console);
123}
124
125static struct sysrq_key_op sysrq_unraw_op = {
126 .handler = sysrq_handle_unraw,
127 .help_msg = "unraw(r)",
128 .action_msg = "Keyboard mode set to system default",
129 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
130};
131#else
132#define sysrq_unraw_op (*(struct sysrq_key_op *)NULL)
133#endif
134
135static void sysrq_handle_crash(int key)
136{
137 char *killer = NULL;
138
139
140
141
142
143
144 rcu_read_unlock();
145 panic_on_oops = 1;
146 wmb();
147 *killer = 1;
148}
149static struct sysrq_key_op sysrq_crash_op = {
150 .handler = sysrq_handle_crash,
151 .help_msg = "crash(c)",
152 .action_msg = "Trigger a crash",
153 .enable_mask = SYSRQ_ENABLE_DUMP,
154};
155
156static void sysrq_handle_reboot(int key)
157{
158 lockdep_off();
159 local_irq_enable();
160 emergency_restart();
161}
162static struct sysrq_key_op sysrq_reboot_op = {
163 .handler = sysrq_handle_reboot,
164 .help_msg = "reboot(b)",
165 .action_msg = "Resetting",
166 .enable_mask = SYSRQ_ENABLE_BOOT,
167};
168
169static void sysrq_handle_sync(int key)
170{
171 emergency_sync();
172}
173static struct sysrq_key_op sysrq_sync_op = {
174 .handler = sysrq_handle_sync,
175 .help_msg = "sync(s)",
176 .action_msg = "Emergency Sync",
177 .enable_mask = SYSRQ_ENABLE_SYNC,
178};
179
180static void sysrq_handle_show_timers(int key)
181{
182 sysrq_timer_list_show();
183}
184
185static struct sysrq_key_op sysrq_show_timers_op = {
186 .handler = sysrq_handle_show_timers,
187 .help_msg = "show-all-timers(q)",
188 .action_msg = "Show clockevent devices & pending hrtimers (no others)",
189};
190
191static void sysrq_handle_mountro(int key)
192{
193 emergency_remount();
194}
195static struct sysrq_key_op sysrq_mountro_op = {
196 .handler = sysrq_handle_mountro,
197 .help_msg = "unmount(u)",
198 .action_msg = "Emergency Remount R/O",
199 .enable_mask = SYSRQ_ENABLE_REMOUNT,
200};
201
202#ifdef CONFIG_LOCKDEP
203static void sysrq_handle_showlocks(int key)
204{
205 debug_show_all_locks();
206}
207
208static struct sysrq_key_op sysrq_showlocks_op = {
209 .handler = sysrq_handle_showlocks,
210 .help_msg = "show-all-locks(d)",
211 .action_msg = "Show Locks Held",
212};
213#else
214#define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL)
215#endif
216
217#ifdef CONFIG_SMP
218static DEFINE_SPINLOCK(show_lock);
219
220static void showacpu(void *dummy)
221{
222 unsigned long flags;
223
224
225 if (idle_cpu(smp_processor_id()))
226 return;
227
228 spin_lock_irqsave(&show_lock, flags);
229 pr_info("CPU%d:\n", smp_processor_id());
230 show_stack(NULL, NULL);
231 spin_unlock_irqrestore(&show_lock, flags);
232}
233
234static void sysrq_showregs_othercpus(struct work_struct *dummy)
235{
236 smp_call_function(showacpu, NULL, 0);
237}
238
239static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
240
241static void sysrq_handle_showallcpus(int key)
242{
243
244
245
246
247
248 if (!trigger_all_cpu_backtrace()) {
249 struct pt_regs *regs = get_irq_regs();
250
251 if (regs) {
252 pr_info("CPU%d:\n", smp_processor_id());
253 show_regs(regs);
254 }
255 schedule_work(&sysrq_showallcpus);
256 }
257}
258
259static struct sysrq_key_op sysrq_showallcpus_op = {
260 .handler = sysrq_handle_showallcpus,
261 .help_msg = "show-backtrace-all-active-cpus(l)",
262 .action_msg = "Show backtrace of all active CPUs",
263 .enable_mask = SYSRQ_ENABLE_DUMP,
264};
265#endif
266
267static void sysrq_handle_showregs(int key)
268{
269 struct pt_regs *regs = get_irq_regs();
270 if (regs)
271 show_regs(regs);
272 perf_event_print_debug();
273}
274static struct sysrq_key_op sysrq_showregs_op = {
275 .handler = sysrq_handle_showregs,
276 .help_msg = "show-registers(p)",
277 .action_msg = "Show Regs",
278 .enable_mask = SYSRQ_ENABLE_DUMP,
279};
280
281static void sysrq_handle_showstate(int key)
282{
283 show_state();
284 show_workqueue_state();
285}
286static struct sysrq_key_op sysrq_showstate_op = {
287 .handler = sysrq_handle_showstate,
288 .help_msg = "show-task-states(t)",
289 .action_msg = "Show State",
290 .enable_mask = SYSRQ_ENABLE_DUMP,
291};
292
293static void sysrq_handle_showstate_blocked(int key)
294{
295 show_state_filter(TASK_UNINTERRUPTIBLE);
296}
297static struct sysrq_key_op sysrq_showstate_blocked_op = {
298 .handler = sysrq_handle_showstate_blocked,
299 .help_msg = "show-blocked-tasks(w)",
300 .action_msg = "Show Blocked State",
301 .enable_mask = SYSRQ_ENABLE_DUMP,
302};
303
304#ifdef CONFIG_TRACING
305#include <linux/ftrace.h>
306
307static void sysrq_ftrace_dump(int key)
308{
309 ftrace_dump(DUMP_ALL);
310}
311static struct sysrq_key_op sysrq_ftrace_dump_op = {
312 .handler = sysrq_ftrace_dump,
313 .help_msg = "dump-ftrace-buffer(z)",
314 .action_msg = "Dump ftrace buffer",
315 .enable_mask = SYSRQ_ENABLE_DUMP,
316};
317#else
318#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
319#endif
320
321static void sysrq_handle_showmem(int key)
322{
323 show_mem(0, NULL);
324}
325static struct sysrq_key_op sysrq_showmem_op = {
326 .handler = sysrq_handle_showmem,
327 .help_msg = "show-memory-usage(m)",
328 .action_msg = "Show Memory",
329 .enable_mask = SYSRQ_ENABLE_DUMP,
330};
331
332
333
334
335static void send_sig_all(int sig)
336{
337 struct task_struct *p;
338
339 read_lock(&tasklist_lock);
340 for_each_process(p) {
341 if (p->flags & PF_KTHREAD)
342 continue;
343 if (is_global_init(p))
344 continue;
345
346 do_send_sig_info(sig, SEND_SIG_FORCED, p, true);
347 }
348 read_unlock(&tasklist_lock);
349}
350
351static void sysrq_handle_term(int key)
352{
353 send_sig_all(SIGTERM);
354 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
355}
356static struct sysrq_key_op sysrq_term_op = {
357 .handler = sysrq_handle_term,
358 .help_msg = "terminate-all-tasks(e)",
359 .action_msg = "Terminate All Tasks",
360 .enable_mask = SYSRQ_ENABLE_SIGNAL,
361};
362
363static void moom_callback(struct work_struct *ignored)
364{
365 const gfp_t gfp_mask = GFP_KERNEL;
366 struct oom_control oc = {
367 .zonelist = node_zonelist(first_memory_node, gfp_mask),
368 .nodemask = NULL,
369 .memcg = NULL,
370 .gfp_mask = gfp_mask,
371 .order = -1,
372 };
373
374 mutex_lock(&oom_lock);
375 if (!out_of_memory(&oc))
376 pr_info("OOM request ignored. No task eligible\n");
377 mutex_unlock(&oom_lock);
378}
379
380static DECLARE_WORK(moom_work, moom_callback);
381
382static void sysrq_handle_moom(int key)
383{
384 schedule_work(&moom_work);
385}
386static struct sysrq_key_op sysrq_moom_op = {
387 .handler = sysrq_handle_moom,
388 .help_msg = "memory-full-oom-kill(f)",
389 .action_msg = "Manual OOM execution",
390 .enable_mask = SYSRQ_ENABLE_SIGNAL,
391};
392
393#ifdef CONFIG_BLOCK
394static void sysrq_handle_thaw(int key)
395{
396 emergency_thaw_all();
397}
398static struct sysrq_key_op sysrq_thaw_op = {
399 .handler = sysrq_handle_thaw,
400 .help_msg = "thaw-filesystems(j)",
401 .action_msg = "Emergency Thaw of all frozen filesystems",
402 .enable_mask = SYSRQ_ENABLE_SIGNAL,
403};
404#endif
405
406static void sysrq_handle_kill(int key)
407{
408 send_sig_all(SIGKILL);
409 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
410}
411static struct sysrq_key_op sysrq_kill_op = {
412 .handler = sysrq_handle_kill,
413 .help_msg = "kill-all-tasks(i)",
414 .action_msg = "Kill All Tasks",
415 .enable_mask = SYSRQ_ENABLE_SIGNAL,
416};
417
418static void sysrq_handle_unrt(int key)
419{
420 normalize_rt_tasks();
421}
422static struct sysrq_key_op sysrq_unrt_op = {
423 .handler = sysrq_handle_unrt,
424 .help_msg = "nice-all-RT-tasks(n)",
425 .action_msg = "Nice All RT Tasks",
426 .enable_mask = SYSRQ_ENABLE_RTNICE,
427};
428
429
430static DEFINE_SPINLOCK(sysrq_key_table_lock);
431
432static struct sysrq_key_op *sysrq_key_table[36] = {
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 &sysrq_loglevel_op,
443
444
445
446
447
448 NULL,
449 &sysrq_reboot_op,
450 &sysrq_crash_op,
451 &sysrq_showlocks_op,
452 &sysrq_term_op,
453 &sysrq_moom_op,
454
455 NULL,
456 NULL,
457 &sysrq_kill_op,
458#ifdef CONFIG_BLOCK
459 &sysrq_thaw_op,
460#else
461 NULL,
462#endif
463 &sysrq_SAK_op,
464#ifdef CONFIG_SMP
465 &sysrq_showallcpus_op,
466#else
467 NULL,
468#endif
469 &sysrq_showmem_op,
470 &sysrq_unrt_op,
471
472 NULL,
473 &sysrq_showregs_op,
474 &sysrq_show_timers_op,
475 &sysrq_unraw_op,
476 &sysrq_sync_op,
477 &sysrq_showstate_op,
478 &sysrq_mountro_op,
479
480 NULL,
481 &sysrq_showstate_blocked_op,
482
483
484
485 NULL,
486
487 NULL,
488 &sysrq_ftrace_dump_op,
489};
490
491
492static int sysrq_key_table_key2index(int key)
493{
494 int retval;
495
496 if ((key >= '0') && (key <= '9'))
497 retval = key - '0';
498 else if ((key >= 'a') && (key <= 'z'))
499 retval = key + 10 - 'a';
500 else
501 retval = -1;
502 return retval;
503}
504
505
506
507
508struct sysrq_key_op *__sysrq_get_key_op(int key)
509{
510 struct sysrq_key_op *op_p = NULL;
511 int i;
512
513 i = sysrq_key_table_key2index(key);
514 if (i != -1)
515 op_p = sysrq_key_table[i];
516
517 return op_p;
518}
519
520static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
521{
522 int i = sysrq_key_table_key2index(key);
523
524 if (i != -1)
525 sysrq_key_table[i] = op_p;
526}
527
528void __handle_sysrq(int key, bool check_mask)
529{
530 struct sysrq_key_op *op_p;
531 int orig_log_level;
532 int i;
533
534 rcu_sysrq_start();
535 rcu_read_lock();
536
537
538
539
540
541
542 orig_log_level = console_loglevel;
543 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
544 pr_info("SysRq : ");
545
546 op_p = __sysrq_get_key_op(key);
547 if (op_p) {
548
549
550
551
552 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
553 pr_cont("%s\n", op_p->action_msg);
554 console_loglevel = orig_log_level;
555 op_p->handler(key);
556 } else {
557 pr_cont("This sysrq operation is disabled.\n");
558 }
559 } else {
560 pr_cont("HELP : ");
561
562 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
563 if (sysrq_key_table[i]) {
564 int j;
565
566 for (j = 0; sysrq_key_table[i] !=
567 sysrq_key_table[j]; j++)
568 ;
569 if (j != i)
570 continue;
571 pr_cont("%s ", sysrq_key_table[i]->help_msg);
572 }
573 }
574 pr_cont("\n");
575 console_loglevel = orig_log_level;
576 }
577 rcu_read_unlock();
578 rcu_sysrq_end();
579}
580
581void handle_sysrq(int key)
582{
583 if (sysrq_on())
584 __handle_sysrq(key, true);
585}
586EXPORT_SYMBOL(handle_sysrq);
587
588#ifdef CONFIG_INPUT
589static int sysrq_reset_downtime_ms;
590
591
592static const unsigned char sysrq_xlate[KEY_CNT] =
593 "\000\0331234567890-=\177\t"
594 "qwertyuiop[]\r\000as"
595 "dfghjkl;'`\000\\zxcv"
596 "bnm,./\000*\000 \000\201\202\203\204\205"
597 "\206\207\210\211\212\000\000789-456+1"
598 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000"
599 "\r\000/";
600
601struct sysrq_state {
602 struct input_handle handle;
603 struct work_struct reinject_work;
604 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
605 unsigned int alt;
606 unsigned int alt_use;
607 bool active;
608 bool need_reinject;
609 bool reinjecting;
610
611
612 bool reset_canceled;
613 bool reset_requested;
614 unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)];
615 int reset_seq_len;
616 int reset_seq_cnt;
617 int reset_seq_version;
618 struct timer_list keyreset_timer;
619};
620
621#define SYSRQ_KEY_RESET_MAX 20
622static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX];
623static unsigned int sysrq_reset_seq_len;
624static unsigned int sysrq_reset_seq_version = 1;
625
626static void sysrq_parse_reset_sequence(struct sysrq_state *state)
627{
628 int i;
629 unsigned short key;
630
631 state->reset_seq_cnt = 0;
632
633 for (i = 0; i < sysrq_reset_seq_len; i++) {
634 key = sysrq_reset_seq[i];
635
636 if (key == KEY_RESERVED || key > KEY_MAX)
637 break;
638
639 __set_bit(key, state->reset_keybit);
640 state->reset_seq_len++;
641
642 if (test_bit(key, state->key_down))
643 state->reset_seq_cnt++;
644 }
645
646
647 state->reset_canceled = state->reset_seq_cnt != 0;
648
649 state->reset_seq_version = sysrq_reset_seq_version;
650}
651
652static void sysrq_do_reset(unsigned long _state)
653{
654 struct sysrq_state *state = (struct sysrq_state *) _state;
655
656 state->reset_requested = true;
657
658 sys_sync();
659 kernel_restart(NULL);
660}
661
662static void sysrq_handle_reset_request(struct sysrq_state *state)
663{
664 if (state->reset_requested)
665 __handle_sysrq(sysrq_xlate[KEY_B], false);
666
667 if (sysrq_reset_downtime_ms)
668 mod_timer(&state->keyreset_timer,
669 jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms));
670 else
671 sysrq_do_reset((unsigned long)state);
672}
673
674static void sysrq_detect_reset_sequence(struct sysrq_state *state,
675 unsigned int code, int value)
676{
677 if (!test_bit(code, state->reset_keybit)) {
678
679
680
681
682
683
684 if (value && state->reset_seq_cnt) {
685 state->reset_canceled = true;
686 del_timer(&state->keyreset_timer);
687 }
688 } else if (value == 0) {
689
690
691
692
693
694 del_timer(&state->keyreset_timer);
695
696 if (--state->reset_seq_cnt == 0)
697 state->reset_canceled = false;
698 } else if (value == 1) {
699
700 if (++state->reset_seq_cnt == state->reset_seq_len &&
701 !state->reset_canceled) {
702 sysrq_handle_reset_request(state);
703 }
704 }
705}
706
707#ifdef CONFIG_OF
708static void sysrq_of_get_keyreset_config(void)
709{
710 u32 key;
711 struct device_node *np;
712 struct property *prop;
713 const __be32 *p;
714
715 np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq");
716 if (!np) {
717 pr_debug("No sysrq node found");
718 return;
719 }
720
721
722 sysrq_reset_seq_len = 0;
723
724 of_property_for_each_u32(np, "keyset", prop, p, key) {
725 if (key == KEY_RESERVED || key > KEY_MAX ||
726 sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX)
727 break;
728
729 sysrq_reset_seq[sysrq_reset_seq_len++] = (unsigned short)key;
730 }
731
732
733 of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms);
734}
735#else
736static void sysrq_of_get_keyreset_config(void)
737{
738}
739#endif
740
741static void sysrq_reinject_alt_sysrq(struct work_struct *work)
742{
743 struct sysrq_state *sysrq =
744 container_of(work, struct sysrq_state, reinject_work);
745 struct input_handle *handle = &sysrq->handle;
746 unsigned int alt_code = sysrq->alt_use;
747
748 if (sysrq->need_reinject) {
749
750 sysrq->reinjecting = true;
751 mb();
752
753
754 input_inject_event(handle, EV_KEY, alt_code, 1);
755 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
756 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
757
758 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
759 input_inject_event(handle, EV_KEY, alt_code, 0);
760 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
761
762 mb();
763 sysrq->reinjecting = false;
764 }
765}
766
767static bool sysrq_handle_keypress(struct sysrq_state *sysrq,
768 unsigned int code, int value)
769{
770 bool was_active = sysrq->active;
771 bool suppress;
772
773 switch (code) {
774
775 case KEY_LEFTALT:
776 case KEY_RIGHTALT:
777 if (!value) {
778
779 if (sysrq->active && code == sysrq->alt_use)
780 sysrq->active = false;
781
782 sysrq->alt = KEY_RESERVED;
783
784 } else if (value != 2) {
785 sysrq->alt = code;
786 sysrq->need_reinject = false;
787 }
788 break;
789
790 case KEY_SYSRQ:
791 if (value == 1 && sysrq->alt != KEY_RESERVED) {
792 sysrq->active = true;
793 sysrq->alt_use = sysrq->alt;
794
795
796
797
798 sysrq->need_reinject = true;
799 }
800
801
802
803
804
805
806
807
808
809 if (sysrq->active)
810 clear_bit(KEY_SYSRQ, sysrq->handle.dev->key);
811
812 break;
813
814 default:
815 if (sysrq->active && value && value != 2) {
816 sysrq->need_reinject = false;
817 __handle_sysrq(sysrq_xlate[code], true);
818 }
819 break;
820 }
821
822 suppress = sysrq->active;
823
824 if (!sysrq->active) {
825
826
827
828
829 if (sysrq->reset_seq_version != sysrq_reset_seq_version)
830 sysrq_parse_reset_sequence(sysrq);
831
832
833
834
835
836
837 if (value)
838 set_bit(code, sysrq->key_down);
839 else
840 clear_bit(code, sysrq->key_down);
841
842 if (was_active)
843 schedule_work(&sysrq->reinject_work);
844
845
846 sysrq_detect_reset_sequence(sysrq, code, value);
847
848 } else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) {
849
850
851
852
853 suppress = false;
854 }
855
856 return suppress;
857}
858
859static bool sysrq_filter(struct input_handle *handle,
860 unsigned int type, unsigned int code, int value)
861{
862 struct sysrq_state *sysrq = handle->private;
863 bool suppress;
864
865
866
867
868
869 if (sysrq->reinjecting)
870 return false;
871
872 switch (type) {
873
874 case EV_SYN:
875 suppress = false;
876 break;
877
878 case EV_KEY:
879 suppress = sysrq_handle_keypress(sysrq, code, value);
880 break;
881
882 default:
883 suppress = sysrq->active;
884 break;
885 }
886
887 return suppress;
888}
889
890static int sysrq_connect(struct input_handler *handler,
891 struct input_dev *dev,
892 const struct input_device_id *id)
893{
894 struct sysrq_state *sysrq;
895 int error;
896
897 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);
898 if (!sysrq)
899 return -ENOMEM;
900
901 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
902
903 sysrq->handle.dev = dev;
904 sysrq->handle.handler = handler;
905 sysrq->handle.name = "sysrq";
906 sysrq->handle.private = sysrq;
907 setup_timer(&sysrq->keyreset_timer,
908 sysrq_do_reset, (unsigned long)sysrq);
909
910 error = input_register_handle(&sysrq->handle);
911 if (error) {
912 pr_err("Failed to register input sysrq handler, error %d\n",
913 error);
914 goto err_free;
915 }
916
917 error = input_open_device(&sysrq->handle);
918 if (error) {
919 pr_err("Failed to open input device, error %d\n", error);
920 goto err_unregister;
921 }
922
923 return 0;
924
925 err_unregister:
926 input_unregister_handle(&sysrq->handle);
927 err_free:
928 kfree(sysrq);
929 return error;
930}
931
932static void sysrq_disconnect(struct input_handle *handle)
933{
934 struct sysrq_state *sysrq = handle->private;
935
936 input_close_device(handle);
937 cancel_work_sync(&sysrq->reinject_work);
938 del_timer_sync(&sysrq->keyreset_timer);
939 input_unregister_handle(handle);
940 kfree(sysrq);
941}
942
943
944
945
946
947
948static const struct input_device_id sysrq_ids[] = {
949 {
950 .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
951 INPUT_DEVICE_ID_MATCH_KEYBIT,
952 .evbit = { [BIT_WORD(EV_KEY)] = BIT_MASK(EV_KEY) },
953 .keybit = { [BIT_WORD(KEY_LEFTALT)] = BIT_MASK(KEY_LEFTALT) },
954 },
955 { },
956};
957
958static struct input_handler sysrq_handler = {
959 .filter = sysrq_filter,
960 .connect = sysrq_connect,
961 .disconnect = sysrq_disconnect,
962 .name = "sysrq",
963 .id_table = sysrq_ids,
964};
965
966static bool sysrq_handler_registered;
967
968static inline void sysrq_register_handler(void)
969{
970 int error;
971
972 sysrq_of_get_keyreset_config();
973
974 error = input_register_handler(&sysrq_handler);
975 if (error)
976 pr_err("Failed to register input handler, error %d", error);
977 else
978 sysrq_handler_registered = true;
979}
980
981static inline void sysrq_unregister_handler(void)
982{
983 if (sysrq_handler_registered) {
984 input_unregister_handler(&sysrq_handler);
985 sysrq_handler_registered = false;
986 }
987}
988
989static int sysrq_reset_seq_param_set(const char *buffer,
990 const struct kernel_param *kp)
991{
992 unsigned long val;
993 int error;
994
995 error = kstrtoul(buffer, 0, &val);
996 if (error < 0)
997 return error;
998
999 if (val > KEY_MAX)
1000 return -EINVAL;
1001
1002 *((unsigned short *)kp->arg) = val;
1003 sysrq_reset_seq_version++;
1004
1005 return 0;
1006}
1007
1008static const struct kernel_param_ops param_ops_sysrq_reset_seq = {
1009 .get = param_get_ushort,
1010 .set = sysrq_reset_seq_param_set,
1011};
1012
1013#define param_check_sysrq_reset_seq(name, p) \
1014 __param_check(name, p, unsigned short)
1015
1016
1017
1018
1019
1020module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq,
1021 &sysrq_reset_seq_len, 0644);
1022
1023module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644);
1024
1025#else
1026
1027static inline void sysrq_register_handler(void)
1028{
1029}
1030
1031static inline void sysrq_unregister_handler(void)
1032{
1033}
1034
1035#endif
1036
1037int sysrq_toggle_support(int enable_mask)
1038{
1039 bool was_enabled = sysrq_on();
1040
1041 sysrq_enabled = enable_mask;
1042
1043 if (was_enabled != sysrq_on()) {
1044 if (sysrq_on())
1045 sysrq_register_handler();
1046 else
1047 sysrq_unregister_handler();
1048 }
1049
1050 return 0;
1051}
1052
1053static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
1054 struct sysrq_key_op *remove_op_p)
1055{
1056 int retval;
1057
1058 spin_lock(&sysrq_key_table_lock);
1059 if (__sysrq_get_key_op(key) == remove_op_p) {
1060 __sysrq_put_key_op(key, insert_op_p);
1061 retval = 0;
1062 } else {
1063 retval = -1;
1064 }
1065 spin_unlock(&sysrq_key_table_lock);
1066
1067
1068
1069
1070
1071
1072 synchronize_rcu();
1073
1074 return retval;
1075}
1076
1077int register_sysrq_key(int key, struct sysrq_key_op *op_p)
1078{
1079 return __sysrq_swap_key_ops(key, op_p, NULL);
1080}
1081EXPORT_SYMBOL(register_sysrq_key);
1082
1083int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
1084{
1085 return __sysrq_swap_key_ops(key, NULL, op_p);
1086}
1087EXPORT_SYMBOL(unregister_sysrq_key);
1088
1089#ifdef CONFIG_PROC_FS
1090
1091
1092
1093static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
1094 size_t count, loff_t *ppos)
1095{
1096 if (count) {
1097 char c;
1098
1099 if (get_user(c, buf))
1100 return -EFAULT;
1101 __handle_sysrq(c, false);
1102 }
1103
1104 return count;
1105}
1106
1107static const struct file_operations proc_sysrq_trigger_operations = {
1108 .write = write_sysrq_trigger,
1109 .llseek = noop_llseek,
1110};
1111
1112static void sysrq_init_procfs(void)
1113{
1114 if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
1115 &proc_sysrq_trigger_operations))
1116 pr_err("Failed to register proc interface\n");
1117}
1118
1119#else
1120
1121static inline void sysrq_init_procfs(void)
1122{
1123}
1124
1125#endif
1126
1127static int __init sysrq_init(void)
1128{
1129 sysrq_init_procfs();
1130
1131 if (sysrq_on())
1132 sysrq_register_handler();
1133
1134 return 0;
1135}
1136device_initcall(sysrq_init);
1137