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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/interrupt.h>
19#include <linux/mm.h>
20#include <linux/fs.h>
21#include <linux/mount.h>
22#include <linux/kdev_t.h>
23#include <linux/major.h>
24#include <linux/reboot.h>
25#include <linux/sysrq.h>
26#include <linux/kbd_kern.h>
27#include <linux/proc_fs.h>
28#include <linux/nmi.h>
29#include <linux/quotaops.h>
30#include <linux/perf_event.h>
31#include <linux/kernel.h>
32#include <linux/module.h>
33#include <linux/suspend.h>
34#include <linux/writeback.h>
35#include <linux/buffer_head.h> /* for fsync_bdev() */
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
45#include <asm/ptrace.h>
46#include <asm/irq_regs.h>
47
48/* Whether we react on sysrq keys or just ignore them */
49static int __read_mostly sysrq_enabled = SYSRQ_DEFAULT_ENABLE;
50static bool __read_mostly sysrq_always_enabled;
51
52static bool sysrq_on(void)
53{
54 return sysrq_enabled || sysrq_always_enabled;
55}
56
57/*
58 * A value of 1 means 'all', other nonzero values are an op mask:
59 */
60static bool sysrq_on_mask(int mask)
61{
62 return sysrq_always_enabled ||
63 sysrq_enabled == 1 ||
64 (sysrq_enabled & mask);
65}
66
67static int __init sysrq_always_enabled_setup(char *str)
68{
69 sysrq_always_enabled = true;
70 pr_info("sysrq always enabled.\n");
71
72 return 1;
73}
74
75__setup("sysrq_always_enabled", sysrq_always_enabled_setup);
76
77
78static void sysrq_handle_loglevel(int key)
79{
80 int i;
81
82 i = key - '0';
83 console_loglevel = 7;
84 printk("Loglevel set to %d\n", i);
85 console_loglevel = i;
86}
87static struct sysrq_key_op sysrq_loglevel_op = {
88 .handler = sysrq_handle_loglevel,
89 .help_msg = "loglevel(0-9)",
90 .action_msg = "Changing Loglevel",
91 .enable_mask = SYSRQ_ENABLE_LOG,
92};
93
94#ifdef CONFIG_VT
95static void sysrq_handle_SAK(int key)
96{
97 struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
98 schedule_work(SAK_work);
99}
100static struct sysrq_key_op sysrq_SAK_op = {
101 .handler = sysrq_handle_SAK,
102 .help_msg = "saK",
103 .action_msg = "SAK",
104 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
105};
106#else
107#define sysrq_SAK_op (*(struct sysrq_key_op *)NULL)
108#endif
109
110#ifdef CONFIG_VT
111static void sysrq_handle_unraw(int key)
112{
113 struct kbd_struct *kbd = &kbd_table[fg_console];
114
115 if (kbd)
116 kbd->kbdmode = default_utf8 ? VC_UNICODE : VC_XLATE;
117}
118static struct sysrq_key_op sysrq_unraw_op = {
119 .handler = sysrq_handle_unraw,
120 .help_msg = "unRaw",
121 .action_msg = "Keyboard mode set to system default",
122 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
123};
124#else
125#define sysrq_unraw_op (*(struct sysrq_key_op *)NULL)
126#endif /* CONFIG_VT */
127
128static void sysrq_handle_crash(int key)
129{
130 char *killer = NULL;
131
132 panic_on_oops = 1; /* force panic */
133 wmb();
134 *killer = 1;
135}
136static struct sysrq_key_op sysrq_crash_op = {
137 .handler = sysrq_handle_crash,
138 .help_msg = "Crash",
139 .action_msg = "Trigger a crash",
140 .enable_mask = SYSRQ_ENABLE_DUMP,
141};
142
143static void sysrq_handle_reboot(int key)
144{
145 lockdep_off();
146 local_irq_enable();
147 emergency_restart();
148}
149static struct sysrq_key_op sysrq_reboot_op = {
150 .handler = sysrq_handle_reboot,
151 .help_msg = "reBoot",
152 .action_msg = "Resetting",
153 .enable_mask = SYSRQ_ENABLE_BOOT,
154};
155
156static void sysrq_handle_sync(int key)
157{
158 emergency_sync();
159}
160static struct sysrq_key_op sysrq_sync_op = {
161 .handler = sysrq_handle_sync,
162 .help_msg = "Sync",
163 .action_msg = "Emergency Sync",
164 .enable_mask = SYSRQ_ENABLE_SYNC,
165};
166
167static void sysrq_handle_show_timers(int key)
168{
169 sysrq_timer_list_show();
170}
171
172static struct sysrq_key_op sysrq_show_timers_op = {
173 .handler = sysrq_handle_show_timers,
174 .help_msg = "show-all-timers(Q)",
175 .action_msg = "Show clockevent devices & pending hrtimers (no others)",
176};
177
178static void sysrq_handle_mountro(int key)
179{
180 emergency_remount();
181}
182static struct sysrq_key_op sysrq_mountro_op = {
183 .handler = sysrq_handle_mountro,
184 .help_msg = "Unmount",
185 .action_msg = "Emergency Remount R/O",
186 .enable_mask = SYSRQ_ENABLE_REMOUNT,
187};
188
189#ifdef CONFIG_LOCKDEP
190static void sysrq_handle_showlocks(int key)
191{
192 debug_show_all_locks();
193}
194
195static struct sysrq_key_op sysrq_showlocks_op = {
196 .handler = sysrq_handle_showlocks,
197 .help_msg = "show-all-locks(D)",
198 .action_msg = "Show Locks Held",
199};
200#else
201#define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL)
202#endif
203
204#ifdef CONFIG_SMP
205static DEFINE_SPINLOCK(show_lock);
206
207static void showacpu(void *dummy)
208{
209 unsigned long flags;
210
211 /* Idle CPUs have no interesting backtrace. */
212 if (idle_cpu(smp_processor_id()))
213 return;
214
215 spin_lock_irqsave(&show_lock, flags);
216 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
217 show_stack(NULL, NULL);
218 spin_unlock_irqrestore(&show_lock, flags);
219}
220
221static void sysrq_showregs_othercpus(struct work_struct *dummy)
222{
223 smp_call_function(showacpu, NULL, 0);
224}
225
226static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
227
228static void sysrq_handle_showallcpus(int key)
229{
230 /*
231 * Fall back to the workqueue based printing if the
232 * backtrace printing did not succeed or the
233 * architecture has no support for it:
234 */
235 if (!trigger_all_cpu_backtrace()) {
236 struct pt_regs *regs = get_irq_regs();
237
238 if (regs) {
239 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
240 show_regs(regs);
241 }
242 schedule_work(&sysrq_showallcpus);
243 }
244}
245
246static struct sysrq_key_op sysrq_showallcpus_op = {
247 .handler = sysrq_handle_showallcpus,
248 .help_msg = "show-backtrace-all-active-cpus(L)",
249 .action_msg = "Show backtrace of all active CPUs",
250 .enable_mask = SYSRQ_ENABLE_DUMP,
251};
252#endif
253
254static void sysrq_handle_showregs(int key)
255{
256 struct pt_regs *regs = get_irq_regs();
257 if (regs)
258 show_regs(regs);
259 perf_event_print_debug();
260}
261static struct sysrq_key_op sysrq_showregs_op = {
262 .handler = sysrq_handle_showregs,
263 .help_msg = "show-registers(P)",
264 .action_msg = "Show Regs",
265 .enable_mask = SYSRQ_ENABLE_DUMP,
266};
267
268static void sysrq_handle_showstate(int key)
269{
270 show_state();
271}
272static struct sysrq_key_op sysrq_showstate_op = {
273 .handler = sysrq_handle_showstate,
274 .help_msg = "show-task-states(T)",
275 .action_msg = "Show State",
276 .enable_mask = SYSRQ_ENABLE_DUMP,
277};
278
279static void sysrq_handle_showstate_blocked(int key)
280{
281 show_state_filter(TASK_UNINTERRUPTIBLE);
282}
283static struct sysrq_key_op sysrq_showstate_blocked_op = {
284 .handler = sysrq_handle_showstate_blocked,
285 .help_msg = "show-blocked-tasks(W)",
286 .action_msg = "Show Blocked State",
287 .enable_mask = SYSRQ_ENABLE_DUMP,
288};
289
290#ifdef CONFIG_TRACING
291#include <linux/ftrace.h>
292
293static void sysrq_ftrace_dump(int key)
294{
295 ftrace_dump(DUMP_ALL);
296}
297static struct sysrq_key_op sysrq_ftrace_dump_op = {
298 .handler = sysrq_ftrace_dump,
299 .help_msg = "dump-ftrace-buffer(Z)",
300 .action_msg = "Dump ftrace buffer",
301 .enable_mask = SYSRQ_ENABLE_DUMP,
302};
303#else
304#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
305#endif
306
307static void sysrq_handle_showmem(int key)
308{
309 show_mem(0);
310}
311static struct sysrq_key_op sysrq_showmem_op = {
312 .handler = sysrq_handle_showmem,
313 .help_msg = "show-memory-usage(M)",
314 .action_msg = "Show Memory",
315 .enable_mask = SYSRQ_ENABLE_DUMP,
316};
317
318/*
319 * Signal sysrq helper function. Sends a signal to all user processes.
320 */
321static void send_sig_all(int sig)
322{
323 struct task_struct *p;
324
325 for_each_process(p) {
326 if (p->mm && !is_global_init(p))
327 /* Not swapper, init nor kernel thread */
328 force_sig(sig, p);
329 }
330}
331
332static void sysrq_handle_term(int key)
333{
334 send_sig_all(SIGTERM);
335 console_loglevel = 8;
336}
337static struct sysrq_key_op sysrq_term_op = {
338 .handler = sysrq_handle_term,
339 .help_msg = "terminate-all-tasks(E)",
340 .action_msg = "Terminate All Tasks",
341 .enable_mask = SYSRQ_ENABLE_SIGNAL,
342};
343
344static void moom_callback(struct work_struct *ignored)
345{
346 out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0, NULL);
347}
348
349static DECLARE_WORK(moom_work, moom_callback);
350
351static void sysrq_handle_moom(int key)
352{
353 schedule_work(&moom_work);
354}
355static struct sysrq_key_op sysrq_moom_op = {
356 .handler = sysrq_handle_moom,
357 .help_msg = "memory-full-oom-kill(F)",
358 .action_msg = "Manual OOM execution",
359 .enable_mask = SYSRQ_ENABLE_SIGNAL,
360};
361
362#ifdef CONFIG_BLOCK
363static void sysrq_handle_thaw(int key)
364{
365 emergency_thaw_all();
366}
367static struct sysrq_key_op sysrq_thaw_op = {
368 .handler = sysrq_handle_thaw,
369 .help_msg = "thaw-filesystems(J)",
370 .action_msg = "Emergency Thaw of all frozen filesystems",
371 .enable_mask = SYSRQ_ENABLE_SIGNAL,
372};
373#endif
374
375static void sysrq_handle_kill(int key)
376{
377 send_sig_all(SIGKILL);
378 console_loglevel = 8;
379}
380static struct sysrq_key_op sysrq_kill_op = {
381 .handler = sysrq_handle_kill,
382 .help_msg = "kill-all-tasks(I)",
383 .action_msg = "Kill All Tasks",
384 .enable_mask = SYSRQ_ENABLE_SIGNAL,
385};
386
387static void sysrq_handle_unrt(int key)
388{
389 normalize_rt_tasks();
390}
391static struct sysrq_key_op sysrq_unrt_op = {
392 .handler = sysrq_handle_unrt,
393 .help_msg = "nice-all-RT-tasks(N)",
394 .action_msg = "Nice All RT Tasks",
395 .enable_mask = SYSRQ_ENABLE_RTNICE,
396};
397
398/* Key Operations table and lock */
399static DEFINE_SPINLOCK(sysrq_key_table_lock);
400
401static struct sysrq_key_op *sysrq_key_table[36] = {
402 &sysrq_loglevel_op, /* 0 */
403 &sysrq_loglevel_op, /* 1 */
404 &sysrq_loglevel_op, /* 2 */
405 &sysrq_loglevel_op, /* 3 */
406 &sysrq_loglevel_op, /* 4 */
407 &sysrq_loglevel_op, /* 5 */
408 &sysrq_loglevel_op, /* 6 */
409 &sysrq_loglevel_op, /* 7 */
410 &sysrq_loglevel_op, /* 8 */
411 &sysrq_loglevel_op, /* 9 */
412
413 /*
414 * a: Don't use for system provided sysrqs, it is handled specially on
415 * sparc and will never arrive.
416 */
417 NULL, /* a */
418 &sysrq_reboot_op, /* b */
419 &sysrq_crash_op, /* c & ibm_emac driver debug */
420 &sysrq_showlocks_op, /* d */
421 &sysrq_term_op, /* e */
422 &sysrq_moom_op, /* f */
423 /* g: May be registered for the kernel debugger */
424 NULL, /* g */
425 NULL, /* h - reserved for help */
426 &sysrq_kill_op, /* i */
427#ifdef CONFIG_BLOCK
428 &sysrq_thaw_op, /* j */
429#else
430 NULL, /* j */
431#endif
432 &sysrq_SAK_op, /* k */
433#ifdef CONFIG_SMP
434 &sysrq_showallcpus_op, /* l */
435#else
436 NULL, /* l */
437#endif
438 &sysrq_showmem_op, /* m */
439 &sysrq_unrt_op, /* n */
440 /* o: This will often be registered as 'Off' at init time */
441 NULL, /* o */
442 &sysrq_showregs_op, /* p */
443 &sysrq_show_timers_op, /* q */
444 &sysrq_unraw_op, /* r */
445 &sysrq_sync_op, /* s */
446 &sysrq_showstate_op, /* t */
447 &sysrq_mountro_op, /* u */
448 /* v: May be registered for frame buffer console restore */
449 NULL, /* v */
450 &sysrq_showstate_blocked_op, /* w */
451 /* x: May be registered on ppc/powerpc for xmon */
452 NULL, /* x */
453 /* y: May be registered on sparc64 for global register dump */
454 NULL, /* y */
455 &sysrq_ftrace_dump_op, /* z */
456};
457
458/* key2index calculation, -1 on invalid index */
459static int sysrq_key_table_key2index(int key)
460{
461 int retval;
462
463 if ((key >= '0') && (key <= '9'))
464 retval = key - '0';
465 else if ((key >= 'a') && (key <= 'z'))
466 retval = key + 10 - 'a';
467 else
468 retval = -1;
469 return retval;
470}
471
472/*
473 * get and put functions for the table, exposed to modules.
474 */
475struct sysrq_key_op *__sysrq_get_key_op(int key)
476{
477 struct sysrq_key_op *op_p = NULL;
478 int i;
479
480 i = sysrq_key_table_key2index(key);
481 if (i != -1)
482 op_p = sysrq_key_table[i];
483
484 return op_p;
485}
486
487static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
488{
489 int i = sysrq_key_table_key2index(key);
490
491 if (i != -1)
492 sysrq_key_table[i] = op_p;
493}
494
495void __handle_sysrq(int key, bool check_mask)
496{
497 struct sysrq_key_op *op_p;
498 int orig_log_level;
499 int i;
500 unsigned long flags;
501
502 spin_lock_irqsave(&sysrq_key_table_lock, flags);
503 /*
504 * Raise the apparent loglevel to maximum so that the sysrq header
505 * is shown to provide the user with positive feedback. We do not
506 * simply emit this at KERN_EMERG as that would change message
507 * routing in the consumers of /proc/kmsg.
508 */
509 orig_log_level = console_loglevel;
510 console_loglevel = 7;
511 printk(KERN_INFO "SysRq : ");
512
513 op_p = __sysrq_get_key_op(key);
514 if (op_p) {
515 /*
516 * Should we check for enabled operations (/proc/sysrq-trigger
517 * should not) and is the invoked operation enabled?
518 */
519 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
520 printk("%s\n", op_p->action_msg);
521 console_loglevel = orig_log_level;
522 op_p->handler(key);
523 } else {
524 printk("This sysrq operation is disabled.\n");
525 }
526 } else {
527 printk("HELP : ");
528 /* Only print the help msg once per handler */
529 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
530 if (sysrq_key_table[i]) {
531 int j;
532
533 for (j = 0; sysrq_key_table[i] !=
534 sysrq_key_table[j]; j++)
535 ;
536 if (j != i)
537 continue;
538 printk("%s ", sysrq_key_table[i]->help_msg);
539 }
540 }
541 printk("\n");
542 console_loglevel = orig_log_level;
543 }
544 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
545}
546
547void handle_sysrq(int key)
548{
549 if (sysrq_on())
550 __handle_sysrq(key, true);
551}
552EXPORT_SYMBOL(handle_sysrq);
553
554#ifdef CONFIG_INPUT
555
556/* Simple translation table for the SysRq keys */
557static const unsigned char sysrq_xlate[KEY_CNT] =
558 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */
559 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */
560 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */
561 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */
562 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */
563 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
564 "\r\000/"; /* 0x60 - 0x6f */
565
566struct sysrq_state {
567 struct input_handle handle;
568 struct work_struct reinject_work;
569 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
570 unsigned int alt;
571 unsigned int alt_use;
572 bool active;
573 bool need_reinject;
574 bool reinjecting;
575};
576
577static void sysrq_reinject_alt_sysrq(struct work_struct *work)
578{
579 struct sysrq_state *sysrq =
580 container_of(work, struct sysrq_state, reinject_work);
581 struct input_handle *handle = &sysrq->handle;
582 unsigned int alt_code = sysrq->alt_use;
583
584 if (sysrq->need_reinject) {
585 /* we do not want the assignment to be reordered */
586 sysrq->reinjecting = true;
587 mb();
588
589 /* Simulate press and release of Alt + SysRq */
590 input_inject_event(handle, EV_KEY, alt_code, 1);
591 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
592 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
593
594 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
595 input_inject_event(handle, EV_KEY, alt_code, 0);
596 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
597
598 mb();
599 sysrq->reinjecting = false;
600 }
601}
602
603static bool sysrq_filter(struct input_handle *handle,
604 unsigned int type, unsigned int code, int value)
605{
606 struct sysrq_state *sysrq = handle->private;
607 bool was_active = sysrq->active;
608 bool suppress;
609
610 /*
611 * Do not filter anything if we are in the process of re-injecting
612 * Alt+SysRq combination.
613 */
614 if (sysrq->reinjecting)
615 return false;
616
617 switch (type) {
618
619 case EV_SYN:
620 suppress = false;
621 break;
622
623 case EV_KEY:
624 switch (code) {
625
626 case KEY_LEFTALT:
627 case KEY_RIGHTALT:
628 if (!value) {
629 /* One of ALTs is being released */
630 if (sysrq->active && code == sysrq->alt_use)
631 sysrq->active = false;
632
633 sysrq->alt = KEY_RESERVED;
634
635 } else if (value != 2) {
636 sysrq->alt = code;
637 sysrq->need_reinject = false;
638 }
639 break;
640
641 case KEY_SYSRQ:
642 if (value == 1 && sysrq->alt != KEY_RESERVED) {
643 sysrq->active = true;
644 sysrq->alt_use = sysrq->alt;
645 /*
646 * If nothing else will be pressed we'll need
647 * to re-inject Alt-SysRq keysroke.
648 */
649 sysrq->need_reinject = true;
650 }
651
652 /*
653 * Pretend that sysrq was never pressed at all. This
654 * is needed to properly handle KGDB which will try
655 * to release all keys after exiting debugger. If we
656 * do not clear key bit it KGDB will end up sending
657 * release events for Alt and SysRq, potentially
658 * triggering print screen function.
659 */
660 if (sysrq->active)
661 clear_bit(KEY_SYSRQ, handle->dev->key);
662
663 break;
664
665 default:
666 if (sysrq->active && value && value != 2) {
667 sysrq->need_reinject = false;
668 __handle_sysrq(sysrq_xlate[code], true);
669 }
670 break;
671 }
672
673 suppress = sysrq->active;
674
675 if (!sysrq->active) {
676 /*
677 * If we are not suppressing key presses keep track of
678 * keyboard state so we can release keys that have been
679 * pressed before entering SysRq mode.
680 */
681 if (value)
682 set_bit(code, sysrq->key_down);
683 else
684 clear_bit(code, sysrq->key_down);
685
686 if (was_active)
687 schedule_work(&sysrq->reinject_work);
688
689 } else if (value == 0 &&
690 test_and_clear_bit(code, sysrq->key_down)) {
691 /*
692 * Pass on release events for keys that was pressed before
693 * entering SysRq mode.
694 */
695 suppress = false;
696 }
697 break;
698
699 default:
700 suppress = sysrq->active;
701 break;
702 }
703
704 return suppress;
705}
706
707static int sysrq_connect(struct input_handler *handler,
708 struct input_dev *dev,
709 const struct input_device_id *id)
710{
711 struct sysrq_state *sysrq;
712 int error;
713
714 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);
715 if (!sysrq)
716 return -ENOMEM;
717
718 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
719
720 sysrq->handle.dev = dev;
721 sysrq->handle.handler = handler;
722 sysrq->handle.name = "sysrq";
723 sysrq->handle.private = sysrq;
724
725 error = input_register_handle(&sysrq->handle);
726 if (error) {
727 pr_err("Failed to register input sysrq handler, error %d\n",
728 error);
729 goto err_free;
730 }
731
732 error = input_open_device(&sysrq->handle);
733 if (error) {
734 pr_err("Failed to open input device, error %d\n", error);
735 goto err_unregister;
736 }
737
738 return 0;
739
740 err_unregister:
741 input_unregister_handle(&sysrq->handle);
742 err_free:
743 kfree(sysrq);
744 return error;
745}
746
747static void sysrq_disconnect(struct input_handle *handle)
748{
749 struct sysrq_state *sysrq = handle->private;
750
751 input_close_device(handle);
752 cancel_work_sync(&sysrq->reinject_work);
753 input_unregister_handle(handle);
754 kfree(sysrq);
755}
756
757/*
758 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all
759 * keyboards have SysRq key predefined and so user may add it to keymap
760 * later, but we expect all such keyboards to have left alt.
761 */
762static const struct input_device_id sysrq_ids[] = {
763 {
764 .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
765 INPUT_DEVICE_ID_MATCH_KEYBIT,
766 .evbit = { BIT_MASK(EV_KEY) },
767 .keybit = { BIT_MASK(KEY_LEFTALT) },
768 },
769 { },
770};
771
772static struct input_handler sysrq_handler = {
773 .filter = sysrq_filter,
774 .connect = sysrq_connect,
775 .disconnect = sysrq_disconnect,
776 .name = "sysrq",
777 .id_table = sysrq_ids,
778};
779
780static bool sysrq_handler_registered;
781
782static inline void sysrq_register_handler(void)
783{
784 int error;
785
786 error = input_register_handler(&sysrq_handler);
787 if (error)
788 pr_err("Failed to register input handler, error %d", error);
789 else
790 sysrq_handler_registered = true;
791}
792
793static inline void sysrq_unregister_handler(void)
794{
795 if (sysrq_handler_registered) {
796 input_unregister_handler(&sysrq_handler);
797 sysrq_handler_registered = false;
798 }
799}
800
801#else
802
803static inline void sysrq_register_handler(void)
804{
805}
806
807static inline void sysrq_unregister_handler(void)
808{
809}
810
811#endif /* CONFIG_INPUT */
812
813int sysrq_toggle_support(int enable_mask)
814{
815 bool was_enabled = sysrq_on();
816
817 sysrq_enabled = enable_mask;
818
819 if (was_enabled != sysrq_on()) {
820 if (sysrq_on())
821 sysrq_register_handler();
822 else
823 sysrq_unregister_handler();
824 }
825
826 return 0;
827}
828
829static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
830 struct sysrq_key_op *remove_op_p)
831{
832 int retval;
833 unsigned long flags;
834
835 spin_lock_irqsave(&sysrq_key_table_lock, flags);
836 if (__sysrq_get_key_op(key) == remove_op_p) {
837 __sysrq_put_key_op(key, insert_op_p);
838 retval = 0;
839 } else {
840 retval = -1;
841 }
842 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
843 return retval;
844}
845
846int register_sysrq_key(int key, struct sysrq_key_op *op_p)
847{
848 return __sysrq_swap_key_ops(key, op_p, NULL);
849}
850EXPORT_SYMBOL(register_sysrq_key);
851
852int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
853{
854 return __sysrq_swap_key_ops(key, NULL, op_p);
855}
856EXPORT_SYMBOL(unregister_sysrq_key);
857
858#ifdef CONFIG_PROC_FS
859/*
860 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
861 */
862static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
863 size_t count, loff_t *ppos)
864{
865 if (count) {
866 char c;
867
868 if (get_user(c, buf))
869 return -EFAULT;
870 __handle_sysrq(c, false);
871 }
872
873 return count;
874}
875
876static const struct file_operations proc_sysrq_trigger_operations = {
877 .write = write_sysrq_trigger,
878 .llseek = noop_llseek,
879};
880
881static void sysrq_init_procfs(void)
882{
883 if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
884 &proc_sysrq_trigger_operations))
885 pr_err("Failed to register proc interface\n");
886}
887
888#else
889
890static inline void sysrq_init_procfs(void)
891{
892}
893
894#endif /* CONFIG_PROC_FS */
895
896static int __init sysrq_init(void)
897{
898 sysrq_init_procfs();
899
900 if (sysrq_on())
901 sysrq_register_handler();
902
903 return 0;
904}
905module_init(sysrq_init);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Linux Magic System Request Key Hacks
4 *
5 * (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
6 * based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz>
7 *
8 * (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
9 * overhauled to use key registration
10 * based upon discusions in irc://irc.openprojects.net/#kernelnewbies
11 *
12 * Copyright (c) 2010 Dmitry Torokhov
13 * Input handler conversion
14 */
15
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/* Whether we react on sysrq keys or just ignore them */
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 * A value of 1 means 'all', other nonzero values are an op mask:
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 /* CONFIG_VT */
134
135static void sysrq_handle_crash(int key)
136{
137 char *killer = NULL;
138
139 /* we need to release the RCU read lock here,
140 * otherwise we get an annoying
141 * 'BUG: sleeping function called from invalid context'
142 * complaint from the kernel before the panic.
143 */
144 rcu_read_unlock();
145 panic_on_oops = 1; /* force panic */
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 /* Idle CPUs have no interesting backtrace. */
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 * Fall back to the workqueue based printing if the
245 * backtrace printing did not succeed or the
246 * architecture has no support for it:
247 */
248 if (!trigger_all_cpu_backtrace()) {
249 struct pt_regs *regs = NULL;
250
251 if (in_irq())
252 regs = get_irq_regs();
253 if (regs) {
254 pr_info("CPU%d:\n", smp_processor_id());
255 show_regs(regs);
256 }
257 schedule_work(&sysrq_showallcpus);
258 }
259}
260
261static struct sysrq_key_op sysrq_showallcpus_op = {
262 .handler = sysrq_handle_showallcpus,
263 .help_msg = "show-backtrace-all-active-cpus(l)",
264 .action_msg = "Show backtrace of all active CPUs",
265 .enable_mask = SYSRQ_ENABLE_DUMP,
266};
267#endif
268
269static void sysrq_handle_showregs(int key)
270{
271 struct pt_regs *regs = NULL;
272
273 if (in_irq())
274 regs = get_irq_regs();
275 if (regs)
276 show_regs(regs);
277 perf_event_print_debug();
278}
279static struct sysrq_key_op sysrq_showregs_op = {
280 .handler = sysrq_handle_showregs,
281 .help_msg = "show-registers(p)",
282 .action_msg = "Show Regs",
283 .enable_mask = SYSRQ_ENABLE_DUMP,
284};
285
286static void sysrq_handle_showstate(int key)
287{
288 show_state();
289 show_workqueue_state();
290}
291static struct sysrq_key_op sysrq_showstate_op = {
292 .handler = sysrq_handle_showstate,
293 .help_msg = "show-task-states(t)",
294 .action_msg = "Show State",
295 .enable_mask = SYSRQ_ENABLE_DUMP,
296};
297
298static void sysrq_handle_showstate_blocked(int key)
299{
300 show_state_filter(TASK_UNINTERRUPTIBLE);
301}
302static struct sysrq_key_op sysrq_showstate_blocked_op = {
303 .handler = sysrq_handle_showstate_blocked,
304 .help_msg = "show-blocked-tasks(w)",
305 .action_msg = "Show Blocked State",
306 .enable_mask = SYSRQ_ENABLE_DUMP,
307};
308
309#ifdef CONFIG_TRACING
310#include <linux/ftrace.h>
311
312static void sysrq_ftrace_dump(int key)
313{
314 ftrace_dump(DUMP_ALL);
315}
316static struct sysrq_key_op sysrq_ftrace_dump_op = {
317 .handler = sysrq_ftrace_dump,
318 .help_msg = "dump-ftrace-buffer(z)",
319 .action_msg = "Dump ftrace buffer",
320 .enable_mask = SYSRQ_ENABLE_DUMP,
321};
322#else
323#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
324#endif
325
326static void sysrq_handle_showmem(int key)
327{
328 show_mem(0, NULL);
329}
330static struct sysrq_key_op sysrq_showmem_op = {
331 .handler = sysrq_handle_showmem,
332 .help_msg = "show-memory-usage(m)",
333 .action_msg = "Show Memory",
334 .enable_mask = SYSRQ_ENABLE_DUMP,
335};
336
337/*
338 * Signal sysrq helper function. Sends a signal to all user processes.
339 */
340static void send_sig_all(int sig)
341{
342 struct task_struct *p;
343
344 read_lock(&tasklist_lock);
345 for_each_process(p) {
346 if (p->flags & PF_KTHREAD)
347 continue;
348 if (is_global_init(p))
349 continue;
350
351 do_send_sig_info(sig, SEND_SIG_FORCED, p, true);
352 }
353 read_unlock(&tasklist_lock);
354}
355
356static void sysrq_handle_term(int key)
357{
358 send_sig_all(SIGTERM);
359 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
360}
361static struct sysrq_key_op sysrq_term_op = {
362 .handler = sysrq_handle_term,
363 .help_msg = "terminate-all-tasks(e)",
364 .action_msg = "Terminate All Tasks",
365 .enable_mask = SYSRQ_ENABLE_SIGNAL,
366};
367
368static void moom_callback(struct work_struct *ignored)
369{
370 const gfp_t gfp_mask = GFP_KERNEL;
371 struct oom_control oc = {
372 .zonelist = node_zonelist(first_memory_node, gfp_mask),
373 .nodemask = NULL,
374 .memcg = NULL,
375 .gfp_mask = gfp_mask,
376 .order = -1,
377 };
378
379 mutex_lock(&oom_lock);
380 if (!out_of_memory(&oc))
381 pr_info("OOM request ignored. No task eligible\n");
382 mutex_unlock(&oom_lock);
383}
384
385static DECLARE_WORK(moom_work, moom_callback);
386
387static void sysrq_handle_moom(int key)
388{
389 schedule_work(&moom_work);
390}
391static struct sysrq_key_op sysrq_moom_op = {
392 .handler = sysrq_handle_moom,
393 .help_msg = "memory-full-oom-kill(f)",
394 .action_msg = "Manual OOM execution",
395 .enable_mask = SYSRQ_ENABLE_SIGNAL,
396};
397
398#ifdef CONFIG_BLOCK
399static void sysrq_handle_thaw(int key)
400{
401 emergency_thaw_all();
402}
403static struct sysrq_key_op sysrq_thaw_op = {
404 .handler = sysrq_handle_thaw,
405 .help_msg = "thaw-filesystems(j)",
406 .action_msg = "Emergency Thaw of all frozen filesystems",
407 .enable_mask = SYSRQ_ENABLE_SIGNAL,
408};
409#endif
410
411static void sysrq_handle_kill(int key)
412{
413 send_sig_all(SIGKILL);
414 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
415}
416static struct sysrq_key_op sysrq_kill_op = {
417 .handler = sysrq_handle_kill,
418 .help_msg = "kill-all-tasks(i)",
419 .action_msg = "Kill All Tasks",
420 .enable_mask = SYSRQ_ENABLE_SIGNAL,
421};
422
423static void sysrq_handle_unrt(int key)
424{
425 normalize_rt_tasks();
426}
427static struct sysrq_key_op sysrq_unrt_op = {
428 .handler = sysrq_handle_unrt,
429 .help_msg = "nice-all-RT-tasks(n)",
430 .action_msg = "Nice All RT Tasks",
431 .enable_mask = SYSRQ_ENABLE_RTNICE,
432};
433
434/* Key Operations table and lock */
435static DEFINE_SPINLOCK(sysrq_key_table_lock);
436
437static struct sysrq_key_op *sysrq_key_table[36] = {
438 &sysrq_loglevel_op, /* 0 */
439 &sysrq_loglevel_op, /* 1 */
440 &sysrq_loglevel_op, /* 2 */
441 &sysrq_loglevel_op, /* 3 */
442 &sysrq_loglevel_op, /* 4 */
443 &sysrq_loglevel_op, /* 5 */
444 &sysrq_loglevel_op, /* 6 */
445 &sysrq_loglevel_op, /* 7 */
446 &sysrq_loglevel_op, /* 8 */
447 &sysrq_loglevel_op, /* 9 */
448
449 /*
450 * a: Don't use for system provided sysrqs, it is handled specially on
451 * sparc and will never arrive.
452 */
453 NULL, /* a */
454 &sysrq_reboot_op, /* b */
455 &sysrq_crash_op, /* c */
456 &sysrq_showlocks_op, /* d */
457 &sysrq_term_op, /* e */
458 &sysrq_moom_op, /* f */
459 /* g: May be registered for the kernel debugger */
460 NULL, /* g */
461 NULL, /* h - reserved for help */
462 &sysrq_kill_op, /* i */
463#ifdef CONFIG_BLOCK
464 &sysrq_thaw_op, /* j */
465#else
466 NULL, /* j */
467#endif
468 &sysrq_SAK_op, /* k */
469#ifdef CONFIG_SMP
470 &sysrq_showallcpus_op, /* l */
471#else
472 NULL, /* l */
473#endif
474 &sysrq_showmem_op, /* m */
475 &sysrq_unrt_op, /* n */
476 /* o: This will often be registered as 'Off' at init time */
477 NULL, /* o */
478 &sysrq_showregs_op, /* p */
479 &sysrq_show_timers_op, /* q */
480 &sysrq_unraw_op, /* r */
481 &sysrq_sync_op, /* s */
482 &sysrq_showstate_op, /* t */
483 &sysrq_mountro_op, /* u */
484 /* v: May be registered for frame buffer console restore */
485 NULL, /* v */
486 &sysrq_showstate_blocked_op, /* w */
487 /* x: May be registered on mips for TLB dump */
488 /* x: May be registered on ppc/powerpc for xmon */
489 /* x: May be registered on sparc64 for global PMU dump */
490 NULL, /* x */
491 /* y: May be registered on sparc64 for global register dump */
492 NULL, /* y */
493 &sysrq_ftrace_dump_op, /* z */
494};
495
496/* key2index calculation, -1 on invalid index */
497static int sysrq_key_table_key2index(int key)
498{
499 int retval;
500
501 if ((key >= '0') && (key <= '9'))
502 retval = key - '0';
503 else if ((key >= 'a') && (key <= 'z'))
504 retval = key + 10 - 'a';
505 else
506 retval = -1;
507 return retval;
508}
509
510/*
511 * get and put functions for the table, exposed to modules.
512 */
513struct sysrq_key_op *__sysrq_get_key_op(int key)
514{
515 struct sysrq_key_op *op_p = NULL;
516 int i;
517
518 i = sysrq_key_table_key2index(key);
519 if (i != -1)
520 op_p = sysrq_key_table[i];
521
522 return op_p;
523}
524
525static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
526{
527 int i = sysrq_key_table_key2index(key);
528
529 if (i != -1)
530 sysrq_key_table[i] = op_p;
531}
532
533void __handle_sysrq(int key, bool check_mask)
534{
535 struct sysrq_key_op *op_p;
536 int orig_log_level;
537 int i;
538
539 rcu_sysrq_start();
540 rcu_read_lock();
541 /*
542 * Raise the apparent loglevel to maximum so that the sysrq header
543 * is shown to provide the user with positive feedback. We do not
544 * simply emit this at KERN_EMERG as that would change message
545 * routing in the consumers of /proc/kmsg.
546 */
547 orig_log_level = console_loglevel;
548 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
549 pr_info("SysRq : ");
550
551 op_p = __sysrq_get_key_op(key);
552 if (op_p) {
553 /*
554 * Should we check for enabled operations (/proc/sysrq-trigger
555 * should not) and is the invoked operation enabled?
556 */
557 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
558 pr_cont("%s\n", op_p->action_msg);
559 console_loglevel = orig_log_level;
560 op_p->handler(key);
561 } else {
562 pr_cont("This sysrq operation is disabled.\n");
563 }
564 } else {
565 pr_cont("HELP : ");
566 /* Only print the help msg once per handler */
567 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
568 if (sysrq_key_table[i]) {
569 int j;
570
571 for (j = 0; sysrq_key_table[i] !=
572 sysrq_key_table[j]; j++)
573 ;
574 if (j != i)
575 continue;
576 pr_cont("%s ", sysrq_key_table[i]->help_msg);
577 }
578 }
579 pr_cont("\n");
580 console_loglevel = orig_log_level;
581 }
582 rcu_read_unlock();
583 rcu_sysrq_end();
584}
585
586void handle_sysrq(int key)
587{
588 if (sysrq_on())
589 __handle_sysrq(key, true);
590}
591EXPORT_SYMBOL(handle_sysrq);
592
593#ifdef CONFIG_INPUT
594static int sysrq_reset_downtime_ms;
595
596/* Simple translation table for the SysRq keys */
597static const unsigned char sysrq_xlate[KEY_CNT] =
598 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */
599 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */
600 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */
601 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */
602 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */
603 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
604 "\r\000/"; /* 0x60 - 0x6f */
605
606struct sysrq_state {
607 struct input_handle handle;
608 struct work_struct reinject_work;
609 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
610 unsigned int alt;
611 unsigned int alt_use;
612 bool active;
613 bool need_reinject;
614 bool reinjecting;
615
616 /* reset sequence handling */
617 bool reset_canceled;
618 bool reset_requested;
619 unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)];
620 int reset_seq_len;
621 int reset_seq_cnt;
622 int reset_seq_version;
623 struct timer_list keyreset_timer;
624};
625
626#define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */
627static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX];
628static unsigned int sysrq_reset_seq_len;
629static unsigned int sysrq_reset_seq_version = 1;
630
631static void sysrq_parse_reset_sequence(struct sysrq_state *state)
632{
633 int i;
634 unsigned short key;
635
636 state->reset_seq_cnt = 0;
637
638 for (i = 0; i < sysrq_reset_seq_len; i++) {
639 key = sysrq_reset_seq[i];
640
641 if (key == KEY_RESERVED || key > KEY_MAX)
642 break;
643
644 __set_bit(key, state->reset_keybit);
645 state->reset_seq_len++;
646
647 if (test_bit(key, state->key_down))
648 state->reset_seq_cnt++;
649 }
650
651 /* Disable reset until old keys are not released */
652 state->reset_canceled = state->reset_seq_cnt != 0;
653
654 state->reset_seq_version = sysrq_reset_seq_version;
655}
656
657static void sysrq_do_reset(struct timer_list *t)
658{
659 struct sysrq_state *state = from_timer(state, t, keyreset_timer);
660
661 state->reset_requested = true;
662
663 ksys_sync();
664 kernel_restart(NULL);
665}
666
667static void sysrq_handle_reset_request(struct sysrq_state *state)
668{
669 if (state->reset_requested)
670 __handle_sysrq(sysrq_xlate[KEY_B], false);
671
672 if (sysrq_reset_downtime_ms)
673 mod_timer(&state->keyreset_timer,
674 jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms));
675 else
676 sysrq_do_reset(&state->keyreset_timer);
677}
678
679static void sysrq_detect_reset_sequence(struct sysrq_state *state,
680 unsigned int code, int value)
681{
682 if (!test_bit(code, state->reset_keybit)) {
683 /*
684 * Pressing any key _not_ in reset sequence cancels
685 * the reset sequence. Also cancelling the timer in
686 * case additional keys were pressed after a reset
687 * has been requested.
688 */
689 if (value && state->reset_seq_cnt) {
690 state->reset_canceled = true;
691 del_timer(&state->keyreset_timer);
692 }
693 } else if (value == 0) {
694 /*
695 * Key release - all keys in the reset sequence need
696 * to be pressed and held for the reset timeout
697 * to hold.
698 */
699 del_timer(&state->keyreset_timer);
700
701 if (--state->reset_seq_cnt == 0)
702 state->reset_canceled = false;
703 } else if (value == 1) {
704 /* key press, not autorepeat */
705 if (++state->reset_seq_cnt == state->reset_seq_len &&
706 !state->reset_canceled) {
707 sysrq_handle_reset_request(state);
708 }
709 }
710}
711
712#ifdef CONFIG_OF
713static void sysrq_of_get_keyreset_config(void)
714{
715 u32 key;
716 struct device_node *np;
717 struct property *prop;
718 const __be32 *p;
719
720 np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq");
721 if (!np) {
722 pr_debug("No sysrq node found");
723 return;
724 }
725
726 /* Reset in case a __weak definition was present */
727 sysrq_reset_seq_len = 0;
728
729 of_property_for_each_u32(np, "keyset", prop, p, key) {
730 if (key == KEY_RESERVED || key > KEY_MAX ||
731 sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX)
732 break;
733
734 sysrq_reset_seq[sysrq_reset_seq_len++] = (unsigned short)key;
735 }
736
737 /* Get reset timeout if any. */
738 of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms);
739}
740#else
741static void sysrq_of_get_keyreset_config(void)
742{
743}
744#endif
745
746static void sysrq_reinject_alt_sysrq(struct work_struct *work)
747{
748 struct sysrq_state *sysrq =
749 container_of(work, struct sysrq_state, reinject_work);
750 struct input_handle *handle = &sysrq->handle;
751 unsigned int alt_code = sysrq->alt_use;
752
753 if (sysrq->need_reinject) {
754 /* we do not want the assignment to be reordered */
755 sysrq->reinjecting = true;
756 mb();
757
758 /* Simulate press and release of Alt + SysRq */
759 input_inject_event(handle, EV_KEY, alt_code, 1);
760 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
761 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
762
763 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
764 input_inject_event(handle, EV_KEY, alt_code, 0);
765 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
766
767 mb();
768 sysrq->reinjecting = false;
769 }
770}
771
772static bool sysrq_handle_keypress(struct sysrq_state *sysrq,
773 unsigned int code, int value)
774{
775 bool was_active = sysrq->active;
776 bool suppress;
777
778 switch (code) {
779
780 case KEY_LEFTALT:
781 case KEY_RIGHTALT:
782 if (!value) {
783 /* One of ALTs is being released */
784 if (sysrq->active && code == sysrq->alt_use)
785 sysrq->active = false;
786
787 sysrq->alt = KEY_RESERVED;
788
789 } else if (value != 2) {
790 sysrq->alt = code;
791 sysrq->need_reinject = false;
792 }
793 break;
794
795 case KEY_SYSRQ:
796 if (value == 1 && sysrq->alt != KEY_RESERVED) {
797 sysrq->active = true;
798 sysrq->alt_use = sysrq->alt;
799 /*
800 * If nothing else will be pressed we'll need
801 * to re-inject Alt-SysRq keysroke.
802 */
803 sysrq->need_reinject = true;
804 }
805
806 /*
807 * Pretend that sysrq was never pressed at all. This
808 * is needed to properly handle KGDB which will try
809 * to release all keys after exiting debugger. If we
810 * do not clear key bit it KGDB will end up sending
811 * release events for Alt and SysRq, potentially
812 * triggering print screen function.
813 */
814 if (sysrq->active)
815 clear_bit(KEY_SYSRQ, sysrq->handle.dev->key);
816
817 break;
818
819 default:
820 if (sysrq->active && value && value != 2) {
821 sysrq->need_reinject = false;
822 __handle_sysrq(sysrq_xlate[code], true);
823 }
824 break;
825 }
826
827 suppress = sysrq->active;
828
829 if (!sysrq->active) {
830
831 /*
832 * See if reset sequence has changed since the last time.
833 */
834 if (sysrq->reset_seq_version != sysrq_reset_seq_version)
835 sysrq_parse_reset_sequence(sysrq);
836
837 /*
838 * If we are not suppressing key presses keep track of
839 * keyboard state so we can release keys that have been
840 * pressed before entering SysRq mode.
841 */
842 if (value)
843 set_bit(code, sysrq->key_down);
844 else
845 clear_bit(code, sysrq->key_down);
846
847 if (was_active)
848 schedule_work(&sysrq->reinject_work);
849
850 /* Check for reset sequence */
851 sysrq_detect_reset_sequence(sysrq, code, value);
852
853 } else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) {
854 /*
855 * Pass on release events for keys that was pressed before
856 * entering SysRq mode.
857 */
858 suppress = false;
859 }
860
861 return suppress;
862}
863
864static bool sysrq_filter(struct input_handle *handle,
865 unsigned int type, unsigned int code, int value)
866{
867 struct sysrq_state *sysrq = handle->private;
868 bool suppress;
869
870 /*
871 * Do not filter anything if we are in the process of re-injecting
872 * Alt+SysRq combination.
873 */
874 if (sysrq->reinjecting)
875 return false;
876
877 switch (type) {
878
879 case EV_SYN:
880 suppress = false;
881 break;
882
883 case EV_KEY:
884 suppress = sysrq_handle_keypress(sysrq, code, value);
885 break;
886
887 default:
888 suppress = sysrq->active;
889 break;
890 }
891
892 return suppress;
893}
894
895static int sysrq_connect(struct input_handler *handler,
896 struct input_dev *dev,
897 const struct input_device_id *id)
898{
899 struct sysrq_state *sysrq;
900 int error;
901
902 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);
903 if (!sysrq)
904 return -ENOMEM;
905
906 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
907
908 sysrq->handle.dev = dev;
909 sysrq->handle.handler = handler;
910 sysrq->handle.name = "sysrq";
911 sysrq->handle.private = sysrq;
912 timer_setup(&sysrq->keyreset_timer, sysrq_do_reset, 0);
913
914 error = input_register_handle(&sysrq->handle);
915 if (error) {
916 pr_err("Failed to register input sysrq handler, error %d\n",
917 error);
918 goto err_free;
919 }
920
921 error = input_open_device(&sysrq->handle);
922 if (error) {
923 pr_err("Failed to open input device, error %d\n", error);
924 goto err_unregister;
925 }
926
927 return 0;
928
929 err_unregister:
930 input_unregister_handle(&sysrq->handle);
931 err_free:
932 kfree(sysrq);
933 return error;
934}
935
936static void sysrq_disconnect(struct input_handle *handle)
937{
938 struct sysrq_state *sysrq = handle->private;
939
940 input_close_device(handle);
941 cancel_work_sync(&sysrq->reinject_work);
942 del_timer_sync(&sysrq->keyreset_timer);
943 input_unregister_handle(handle);
944 kfree(sysrq);
945}
946
947/*
948 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all
949 * keyboards have SysRq key predefined and so user may add it to keymap
950 * later, but we expect all such keyboards to have left alt.
951 */
952static const struct input_device_id sysrq_ids[] = {
953 {
954 .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
955 INPUT_DEVICE_ID_MATCH_KEYBIT,
956 .evbit = { [BIT_WORD(EV_KEY)] = BIT_MASK(EV_KEY) },
957 .keybit = { [BIT_WORD(KEY_LEFTALT)] = BIT_MASK(KEY_LEFTALT) },
958 },
959 { },
960};
961
962static struct input_handler sysrq_handler = {
963 .filter = sysrq_filter,
964 .connect = sysrq_connect,
965 .disconnect = sysrq_disconnect,
966 .name = "sysrq",
967 .id_table = sysrq_ids,
968};
969
970static bool sysrq_handler_registered;
971
972static inline void sysrq_register_handler(void)
973{
974 int error;
975
976 sysrq_of_get_keyreset_config();
977
978 error = input_register_handler(&sysrq_handler);
979 if (error)
980 pr_err("Failed to register input handler, error %d", error);
981 else
982 sysrq_handler_registered = true;
983}
984
985static inline void sysrq_unregister_handler(void)
986{
987 if (sysrq_handler_registered) {
988 input_unregister_handler(&sysrq_handler);
989 sysrq_handler_registered = false;
990 }
991}
992
993static int sysrq_reset_seq_param_set(const char *buffer,
994 const struct kernel_param *kp)
995{
996 unsigned long val;
997 int error;
998
999 error = kstrtoul(buffer, 0, &val);
1000 if (error < 0)
1001 return error;
1002
1003 if (val > KEY_MAX)
1004 return -EINVAL;
1005
1006 *((unsigned short *)kp->arg) = val;
1007 sysrq_reset_seq_version++;
1008
1009 return 0;
1010}
1011
1012static const struct kernel_param_ops param_ops_sysrq_reset_seq = {
1013 .get = param_get_ushort,
1014 .set = sysrq_reset_seq_param_set,
1015};
1016
1017#define param_check_sysrq_reset_seq(name, p) \
1018 __param_check(name, p, unsigned short)
1019
1020/*
1021 * not really modular, but the easiest way to keep compat with existing
1022 * bootargs behaviour is to continue using module_param here.
1023 */
1024module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq,
1025 &sysrq_reset_seq_len, 0644);
1026
1027module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644);
1028
1029#else
1030
1031static inline void sysrq_register_handler(void)
1032{
1033}
1034
1035static inline void sysrq_unregister_handler(void)
1036{
1037}
1038
1039#endif /* CONFIG_INPUT */
1040
1041int sysrq_toggle_support(int enable_mask)
1042{
1043 bool was_enabled = sysrq_on();
1044
1045 sysrq_enabled = enable_mask;
1046
1047 if (was_enabled != sysrq_on()) {
1048 if (sysrq_on())
1049 sysrq_register_handler();
1050 else
1051 sysrq_unregister_handler();
1052 }
1053
1054 return 0;
1055}
1056
1057static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
1058 struct sysrq_key_op *remove_op_p)
1059{
1060 int retval;
1061
1062 spin_lock(&sysrq_key_table_lock);
1063 if (__sysrq_get_key_op(key) == remove_op_p) {
1064 __sysrq_put_key_op(key, insert_op_p);
1065 retval = 0;
1066 } else {
1067 retval = -1;
1068 }
1069 spin_unlock(&sysrq_key_table_lock);
1070
1071 /*
1072 * A concurrent __handle_sysrq either got the old op or the new op.
1073 * Wait for it to go away before returning, so the code for an old
1074 * op is not freed (eg. on module unload) while it is in use.
1075 */
1076 synchronize_rcu();
1077
1078 return retval;
1079}
1080
1081int register_sysrq_key(int key, struct sysrq_key_op *op_p)
1082{
1083 return __sysrq_swap_key_ops(key, op_p, NULL);
1084}
1085EXPORT_SYMBOL(register_sysrq_key);
1086
1087int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
1088{
1089 return __sysrq_swap_key_ops(key, NULL, op_p);
1090}
1091EXPORT_SYMBOL(unregister_sysrq_key);
1092
1093#ifdef CONFIG_PROC_FS
1094/*
1095 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
1096 */
1097static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
1098 size_t count, loff_t *ppos)
1099{
1100 if (count) {
1101 char c;
1102
1103 if (get_user(c, buf))
1104 return -EFAULT;
1105 __handle_sysrq(c, false);
1106 }
1107
1108 return count;
1109}
1110
1111static const struct file_operations proc_sysrq_trigger_operations = {
1112 .write = write_sysrq_trigger,
1113 .llseek = noop_llseek,
1114};
1115
1116static void sysrq_init_procfs(void)
1117{
1118 if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
1119 &proc_sysrq_trigger_operations))
1120 pr_err("Failed to register proc interface\n");
1121}
1122
1123#else
1124
1125static inline void sysrq_init_procfs(void)
1126{
1127}
1128
1129#endif /* CONFIG_PROC_FS */
1130
1131static int __init sysrq_init(void)
1132{
1133 sysrq_init_procfs();
1134
1135 if (sysrq_on())
1136 sysrq_register_handler();
1137
1138 return 0;
1139}
1140device_initcall(sysrq_init);