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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/*
2 * Linux Magic System Request Key Hacks
3 *
4 * (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
5 * based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz>
6 *
7 * (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
8 * overhauled to use key registration
9 * based upon discusions in irc://irc.openprojects.net/#kernelnewbies
10 *
11 * Copyright (c) 2010 Dmitry Torokhov
12 * Input handler conversion
13 */
14
15#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
16
17#include <linux/sched.h>
18#include <linux/sched/rt.h>
19#include <linux/interrupt.h>
20#include <linux/mm.h>
21#include <linux/fs.h>
22#include <linux/mount.h>
23#include <linux/kdev_t.h>
24#include <linux/major.h>
25#include <linux/reboot.h>
26#include <linux/sysrq.h>
27#include <linux/kbd_kern.h>
28#include <linux/proc_fs.h>
29#include <linux/nmi.h>
30#include <linux/quotaops.h>
31#include <linux/perf_event.h>
32#include <linux/kernel.h>
33#include <linux/module.h>
34#include <linux/suspend.h>
35#include <linux/writeback.h>
36#include <linux/swap.h>
37#include <linux/spinlock.h>
38#include <linux/vt_kern.h>
39#include <linux/workqueue.h>
40#include <linux/hrtimer.h>
41#include <linux/oom.h>
42#include <linux/slab.h>
43#include <linux/input.h>
44#include <linux/uaccess.h>
45#include <linux/moduleparam.h>
46#include <linux/jiffies.h>
47#include <linux/syscalls.h>
48#include <linux/of.h>
49#include <linux/rcupdate.h>
50
51#include <asm/ptrace.h>
52#include <asm/irq_regs.h>
53
54/* Whether we react on sysrq keys or just ignore them */
55static int __read_mostly sysrq_enabled = CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE;
56static bool __read_mostly sysrq_always_enabled;
57
58static bool sysrq_on(void)
59{
60 return sysrq_enabled || sysrq_always_enabled;
61}
62
63/*
64 * A value of 1 means 'all', other nonzero values are an op mask:
65 */
66static bool sysrq_on_mask(int mask)
67{
68 return sysrq_always_enabled ||
69 sysrq_enabled == 1 ||
70 (sysrq_enabled & mask);
71}
72
73static int __init sysrq_always_enabled_setup(char *str)
74{
75 sysrq_always_enabled = true;
76 pr_info("sysrq always enabled.\n");
77
78 return 1;
79}
80
81__setup("sysrq_always_enabled", sysrq_always_enabled_setup);
82
83
84static void sysrq_handle_loglevel(int key)
85{
86 int i;
87
88 i = key - '0';
89 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
90 pr_info("Loglevel set to %d\n", i);
91 console_loglevel = i;
92}
93static struct sysrq_key_op sysrq_loglevel_op = {
94 .handler = sysrq_handle_loglevel,
95 .help_msg = "loglevel(0-9)",
96 .action_msg = "Changing Loglevel",
97 .enable_mask = SYSRQ_ENABLE_LOG,
98};
99
100#ifdef CONFIG_VT
101static void sysrq_handle_SAK(int key)
102{
103 struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
104 schedule_work(SAK_work);
105}
106static struct sysrq_key_op sysrq_SAK_op = {
107 .handler = sysrq_handle_SAK,
108 .help_msg = "sak(k)",
109 .action_msg = "SAK",
110 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
111};
112#else
113#define sysrq_SAK_op (*(struct sysrq_key_op *)NULL)
114#endif
115
116#ifdef CONFIG_VT
117static void sysrq_handle_unraw(int key)
118{
119 vt_reset_unicode(fg_console);
120}
121
122static struct sysrq_key_op sysrq_unraw_op = {
123 .handler = sysrq_handle_unraw,
124 .help_msg = "unraw(r)",
125 .action_msg = "Keyboard mode set to system default",
126 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
127};
128#else
129#define sysrq_unraw_op (*(struct sysrq_key_op *)NULL)
130#endif /* CONFIG_VT */
131
132static void sysrq_handle_crash(int key)
133{
134 char *killer = NULL;
135
136 /* we need to release the RCU read lock here,
137 * otherwise we get an annoying
138 * 'BUG: sleeping function called from invalid context'
139 * complaint from the kernel before the panic.
140 */
141 rcu_read_unlock();
142 panic_on_oops = 1; /* force panic */
143 wmb();
144 *killer = 1;
145}
146static struct sysrq_key_op sysrq_crash_op = {
147 .handler = sysrq_handle_crash,
148 .help_msg = "crash(c)",
149 .action_msg = "Trigger a crash",
150 .enable_mask = SYSRQ_ENABLE_DUMP,
151};
152
153static void sysrq_handle_reboot(int key)
154{
155 lockdep_off();
156 local_irq_enable();
157 emergency_restart();
158}
159static struct sysrq_key_op sysrq_reboot_op = {
160 .handler = sysrq_handle_reboot,
161 .help_msg = "reboot(b)",
162 .action_msg = "Resetting",
163 .enable_mask = SYSRQ_ENABLE_BOOT,
164};
165
166static void sysrq_handle_sync(int key)
167{
168 emergency_sync();
169}
170static struct sysrq_key_op sysrq_sync_op = {
171 .handler = sysrq_handle_sync,
172 .help_msg = "sync(s)",
173 .action_msg = "Emergency Sync",
174 .enable_mask = SYSRQ_ENABLE_SYNC,
175};
176
177static void sysrq_handle_show_timers(int key)
178{
179 sysrq_timer_list_show();
180}
181
182static struct sysrq_key_op sysrq_show_timers_op = {
183 .handler = sysrq_handle_show_timers,
184 .help_msg = "show-all-timers(q)",
185 .action_msg = "Show clockevent devices & pending hrtimers (no others)",
186};
187
188static void sysrq_handle_mountro(int key)
189{
190 emergency_remount();
191}
192static struct sysrq_key_op sysrq_mountro_op = {
193 .handler = sysrq_handle_mountro,
194 .help_msg = "unmount(u)",
195 .action_msg = "Emergency Remount R/O",
196 .enable_mask = SYSRQ_ENABLE_REMOUNT,
197};
198
199#ifdef CONFIG_LOCKDEP
200static void sysrq_handle_showlocks(int key)
201{
202 debug_show_all_locks();
203}
204
205static struct sysrq_key_op sysrq_showlocks_op = {
206 .handler = sysrq_handle_showlocks,
207 .help_msg = "show-all-locks(d)",
208 .action_msg = "Show Locks Held",
209};
210#else
211#define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL)
212#endif
213
214#ifdef CONFIG_SMP
215static DEFINE_SPINLOCK(show_lock);
216
217static void showacpu(void *dummy)
218{
219 unsigned long flags;
220
221 /* Idle CPUs have no interesting backtrace. */
222 if (idle_cpu(smp_processor_id()))
223 return;
224
225 spin_lock_irqsave(&show_lock, flags);
226 pr_info("CPU%d:\n", smp_processor_id());
227 show_stack(NULL, NULL);
228 spin_unlock_irqrestore(&show_lock, flags);
229}
230
231static void sysrq_showregs_othercpus(struct work_struct *dummy)
232{
233 smp_call_function(showacpu, NULL, 0);
234}
235
236static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
237
238static void sysrq_handle_showallcpus(int key)
239{
240 /*
241 * Fall back to the workqueue based printing if the
242 * backtrace printing did not succeed or the
243 * architecture has no support for it:
244 */
245 if (!trigger_all_cpu_backtrace()) {
246 struct pt_regs *regs = get_irq_regs();
247
248 if (regs) {
249 pr_info("CPU%d:\n", smp_processor_id());
250 show_regs(regs);
251 }
252 schedule_work(&sysrq_showallcpus);
253 }
254}
255
256static struct sysrq_key_op sysrq_showallcpus_op = {
257 .handler = sysrq_handle_showallcpus,
258 .help_msg = "show-backtrace-all-active-cpus(l)",
259 .action_msg = "Show backtrace of all active CPUs",
260 .enable_mask = SYSRQ_ENABLE_DUMP,
261};
262#endif
263
264static void sysrq_handle_showregs(int key)
265{
266 struct pt_regs *regs = get_irq_regs();
267 if (regs)
268 show_regs(regs);
269 perf_event_print_debug();
270}
271static struct sysrq_key_op sysrq_showregs_op = {
272 .handler = sysrq_handle_showregs,
273 .help_msg = "show-registers(p)",
274 .action_msg = "Show Regs",
275 .enable_mask = SYSRQ_ENABLE_DUMP,
276};
277
278static void sysrq_handle_showstate(int key)
279{
280 show_state();
281 show_workqueue_state();
282}
283static struct sysrq_key_op sysrq_showstate_op = {
284 .handler = sysrq_handle_showstate,
285 .help_msg = "show-task-states(t)",
286 .action_msg = "Show State",
287 .enable_mask = SYSRQ_ENABLE_DUMP,
288};
289
290static void sysrq_handle_showstate_blocked(int key)
291{
292 show_state_filter(TASK_UNINTERRUPTIBLE);
293}
294static struct sysrq_key_op sysrq_showstate_blocked_op = {
295 .handler = sysrq_handle_showstate_blocked,
296 .help_msg = "show-blocked-tasks(w)",
297 .action_msg = "Show Blocked State",
298 .enable_mask = SYSRQ_ENABLE_DUMP,
299};
300
301#ifdef CONFIG_TRACING
302#include <linux/ftrace.h>
303
304static void sysrq_ftrace_dump(int key)
305{
306 ftrace_dump(DUMP_ALL);
307}
308static struct sysrq_key_op sysrq_ftrace_dump_op = {
309 .handler = sysrq_ftrace_dump,
310 .help_msg = "dump-ftrace-buffer(z)",
311 .action_msg = "Dump ftrace buffer",
312 .enable_mask = SYSRQ_ENABLE_DUMP,
313};
314#else
315#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
316#endif
317
318static void sysrq_handle_showmem(int key)
319{
320 show_mem(0);
321}
322static struct sysrq_key_op sysrq_showmem_op = {
323 .handler = sysrq_handle_showmem,
324 .help_msg = "show-memory-usage(m)",
325 .action_msg = "Show Memory",
326 .enable_mask = SYSRQ_ENABLE_DUMP,
327};
328
329/*
330 * Signal sysrq helper function. Sends a signal to all user processes.
331 */
332static void send_sig_all(int sig)
333{
334 struct task_struct *p;
335
336 read_lock(&tasklist_lock);
337 for_each_process(p) {
338 if (p->flags & PF_KTHREAD)
339 continue;
340 if (is_global_init(p))
341 continue;
342
343 do_send_sig_info(sig, SEND_SIG_FORCED, p, true);
344 }
345 read_unlock(&tasklist_lock);
346}
347
348static void sysrq_handle_term(int key)
349{
350 send_sig_all(SIGTERM);
351 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
352}
353static struct sysrq_key_op sysrq_term_op = {
354 .handler = sysrq_handle_term,
355 .help_msg = "terminate-all-tasks(e)",
356 .action_msg = "Terminate All Tasks",
357 .enable_mask = SYSRQ_ENABLE_SIGNAL,
358};
359
360static void moom_callback(struct work_struct *ignored)
361{
362 const gfp_t gfp_mask = GFP_KERNEL;
363 struct oom_control oc = {
364 .zonelist = node_zonelist(first_memory_node, gfp_mask),
365 .nodemask = NULL,
366 .memcg = NULL,
367 .gfp_mask = gfp_mask,
368 .order = -1,
369 };
370
371 mutex_lock(&oom_lock);
372 if (!out_of_memory(&oc))
373 pr_info("OOM request ignored because killer is disabled\n");
374 mutex_unlock(&oom_lock);
375}
376
377static DECLARE_WORK(moom_work, moom_callback);
378
379static void sysrq_handle_moom(int key)
380{
381 schedule_work(&moom_work);
382}
383static struct sysrq_key_op sysrq_moom_op = {
384 .handler = sysrq_handle_moom,
385 .help_msg = "memory-full-oom-kill(f)",
386 .action_msg = "Manual OOM execution",
387 .enable_mask = SYSRQ_ENABLE_SIGNAL,
388};
389
390#ifdef CONFIG_BLOCK
391static void sysrq_handle_thaw(int key)
392{
393 emergency_thaw_all();
394}
395static struct sysrq_key_op sysrq_thaw_op = {
396 .handler = sysrq_handle_thaw,
397 .help_msg = "thaw-filesystems(j)",
398 .action_msg = "Emergency Thaw of all frozen filesystems",
399 .enable_mask = SYSRQ_ENABLE_SIGNAL,
400};
401#endif
402
403static void sysrq_handle_kill(int key)
404{
405 send_sig_all(SIGKILL);
406 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
407}
408static struct sysrq_key_op sysrq_kill_op = {
409 .handler = sysrq_handle_kill,
410 .help_msg = "kill-all-tasks(i)",
411 .action_msg = "Kill All Tasks",
412 .enable_mask = SYSRQ_ENABLE_SIGNAL,
413};
414
415static void sysrq_handle_unrt(int key)
416{
417 normalize_rt_tasks();
418}
419static struct sysrq_key_op sysrq_unrt_op = {
420 .handler = sysrq_handle_unrt,
421 .help_msg = "nice-all-RT-tasks(n)",
422 .action_msg = "Nice All RT Tasks",
423 .enable_mask = SYSRQ_ENABLE_RTNICE,
424};
425
426/* Key Operations table and lock */
427static DEFINE_SPINLOCK(sysrq_key_table_lock);
428
429static struct sysrq_key_op *sysrq_key_table[36] = {
430 &sysrq_loglevel_op, /* 0 */
431 &sysrq_loglevel_op, /* 1 */
432 &sysrq_loglevel_op, /* 2 */
433 &sysrq_loglevel_op, /* 3 */
434 &sysrq_loglevel_op, /* 4 */
435 &sysrq_loglevel_op, /* 5 */
436 &sysrq_loglevel_op, /* 6 */
437 &sysrq_loglevel_op, /* 7 */
438 &sysrq_loglevel_op, /* 8 */
439 &sysrq_loglevel_op, /* 9 */
440
441 /*
442 * a: Don't use for system provided sysrqs, it is handled specially on
443 * sparc and will never arrive.
444 */
445 NULL, /* a */
446 &sysrq_reboot_op, /* b */
447 &sysrq_crash_op, /* c & ibm_emac driver debug */
448 &sysrq_showlocks_op, /* d */
449 &sysrq_term_op, /* e */
450 &sysrq_moom_op, /* f */
451 /* g: May be registered for the kernel debugger */
452 NULL, /* g */
453 NULL, /* h - reserved for help */
454 &sysrq_kill_op, /* i */
455#ifdef CONFIG_BLOCK
456 &sysrq_thaw_op, /* j */
457#else
458 NULL, /* j */
459#endif
460 &sysrq_SAK_op, /* k */
461#ifdef CONFIG_SMP
462 &sysrq_showallcpus_op, /* l */
463#else
464 NULL, /* l */
465#endif
466 &sysrq_showmem_op, /* m */
467 &sysrq_unrt_op, /* n */
468 /* o: This will often be registered as 'Off' at init time */
469 NULL, /* o */
470 &sysrq_showregs_op, /* p */
471 &sysrq_show_timers_op, /* q */
472 &sysrq_unraw_op, /* r */
473 &sysrq_sync_op, /* s */
474 &sysrq_showstate_op, /* t */
475 &sysrq_mountro_op, /* u */
476 /* v: May be registered for frame buffer console restore */
477 NULL, /* v */
478 &sysrq_showstate_blocked_op, /* w */
479 /* x: May be registered on mips for TLB dump */
480 /* x: May be registered on ppc/powerpc for xmon */
481 /* x: May be registered on sparc64 for global PMU dump */
482 NULL, /* x */
483 /* y: May be registered on sparc64 for global register dump */
484 NULL, /* y */
485 &sysrq_ftrace_dump_op, /* z */
486};
487
488/* key2index calculation, -1 on invalid index */
489static int sysrq_key_table_key2index(int key)
490{
491 int retval;
492
493 if ((key >= '0') && (key <= '9'))
494 retval = key - '0';
495 else if ((key >= 'a') && (key <= 'z'))
496 retval = key + 10 - 'a';
497 else
498 retval = -1;
499 return retval;
500}
501
502/*
503 * get and put functions for the table, exposed to modules.
504 */
505struct sysrq_key_op *__sysrq_get_key_op(int key)
506{
507 struct sysrq_key_op *op_p = NULL;
508 int i;
509
510 i = sysrq_key_table_key2index(key);
511 if (i != -1)
512 op_p = sysrq_key_table[i];
513
514 return op_p;
515}
516
517static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
518{
519 int i = sysrq_key_table_key2index(key);
520
521 if (i != -1)
522 sysrq_key_table[i] = op_p;
523}
524
525void __handle_sysrq(int key, bool check_mask)
526{
527 struct sysrq_key_op *op_p;
528 int orig_log_level;
529 int i;
530
531 rcu_sysrq_start();
532 rcu_read_lock();
533 /*
534 * Raise the apparent loglevel to maximum so that the sysrq header
535 * is shown to provide the user with positive feedback. We do not
536 * simply emit this at KERN_EMERG as that would change message
537 * routing in the consumers of /proc/kmsg.
538 */
539 orig_log_level = console_loglevel;
540 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
541 pr_info("SysRq : ");
542
543 op_p = __sysrq_get_key_op(key);
544 if (op_p) {
545 /*
546 * Should we check for enabled operations (/proc/sysrq-trigger
547 * should not) and is the invoked operation enabled?
548 */
549 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
550 pr_cont("%s\n", op_p->action_msg);
551 console_loglevel = orig_log_level;
552 op_p->handler(key);
553 } else {
554 pr_cont("This sysrq operation is disabled.\n");
555 }
556 } else {
557 pr_cont("HELP : ");
558 /* Only print the help msg once per handler */
559 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
560 if (sysrq_key_table[i]) {
561 int j;
562
563 for (j = 0; sysrq_key_table[i] !=
564 sysrq_key_table[j]; j++)
565 ;
566 if (j != i)
567 continue;
568 pr_cont("%s ", sysrq_key_table[i]->help_msg);
569 }
570 }
571 pr_cont("\n");
572 console_loglevel = orig_log_level;
573 }
574 rcu_read_unlock();
575 rcu_sysrq_end();
576}
577
578void handle_sysrq(int key)
579{
580 if (sysrq_on())
581 __handle_sysrq(key, true);
582}
583EXPORT_SYMBOL(handle_sysrq);
584
585#ifdef CONFIG_INPUT
586static int sysrq_reset_downtime_ms;
587
588/* Simple translation table for the SysRq keys */
589static const unsigned char sysrq_xlate[KEY_CNT] =
590 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */
591 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */
592 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */
593 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */
594 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */
595 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
596 "\r\000/"; /* 0x60 - 0x6f */
597
598struct sysrq_state {
599 struct input_handle handle;
600 struct work_struct reinject_work;
601 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
602 unsigned int alt;
603 unsigned int alt_use;
604 bool active;
605 bool need_reinject;
606 bool reinjecting;
607
608 /* reset sequence handling */
609 bool reset_canceled;
610 bool reset_requested;
611 unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)];
612 int reset_seq_len;
613 int reset_seq_cnt;
614 int reset_seq_version;
615 struct timer_list keyreset_timer;
616};
617
618#define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */
619static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX];
620static unsigned int sysrq_reset_seq_len;
621static unsigned int sysrq_reset_seq_version = 1;
622
623static void sysrq_parse_reset_sequence(struct sysrq_state *state)
624{
625 int i;
626 unsigned short key;
627
628 state->reset_seq_cnt = 0;
629
630 for (i = 0; i < sysrq_reset_seq_len; i++) {
631 key = sysrq_reset_seq[i];
632
633 if (key == KEY_RESERVED || key > KEY_MAX)
634 break;
635
636 __set_bit(key, state->reset_keybit);
637 state->reset_seq_len++;
638
639 if (test_bit(key, state->key_down))
640 state->reset_seq_cnt++;
641 }
642
643 /* Disable reset until old keys are not released */
644 state->reset_canceled = state->reset_seq_cnt != 0;
645
646 state->reset_seq_version = sysrq_reset_seq_version;
647}
648
649static void sysrq_do_reset(unsigned long _state)
650{
651 struct sysrq_state *state = (struct sysrq_state *) _state;
652
653 state->reset_requested = true;
654
655 sys_sync();
656 kernel_restart(NULL);
657}
658
659static void sysrq_handle_reset_request(struct sysrq_state *state)
660{
661 if (state->reset_requested)
662 __handle_sysrq(sysrq_xlate[KEY_B], false);
663
664 if (sysrq_reset_downtime_ms)
665 mod_timer(&state->keyreset_timer,
666 jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms));
667 else
668 sysrq_do_reset((unsigned long)state);
669}
670
671static void sysrq_detect_reset_sequence(struct sysrq_state *state,
672 unsigned int code, int value)
673{
674 if (!test_bit(code, state->reset_keybit)) {
675 /*
676 * Pressing any key _not_ in reset sequence cancels
677 * the reset sequence. Also cancelling the timer in
678 * case additional keys were pressed after a reset
679 * has been requested.
680 */
681 if (value && state->reset_seq_cnt) {
682 state->reset_canceled = true;
683 del_timer(&state->keyreset_timer);
684 }
685 } else if (value == 0) {
686 /*
687 * Key release - all keys in the reset sequence need
688 * to be pressed and held for the reset timeout
689 * to hold.
690 */
691 del_timer(&state->keyreset_timer);
692
693 if (--state->reset_seq_cnt == 0)
694 state->reset_canceled = false;
695 } else if (value == 1) {
696 /* key press, not autorepeat */
697 if (++state->reset_seq_cnt == state->reset_seq_len &&
698 !state->reset_canceled) {
699 sysrq_handle_reset_request(state);
700 }
701 }
702}
703
704#ifdef CONFIG_OF
705static void sysrq_of_get_keyreset_config(void)
706{
707 u32 key;
708 struct device_node *np;
709 struct property *prop;
710 const __be32 *p;
711
712 np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq");
713 if (!np) {
714 pr_debug("No sysrq node found");
715 return;
716 }
717
718 /* Reset in case a __weak definition was present */
719 sysrq_reset_seq_len = 0;
720
721 of_property_for_each_u32(np, "keyset", prop, p, key) {
722 if (key == KEY_RESERVED || key > KEY_MAX ||
723 sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX)
724 break;
725
726 sysrq_reset_seq[sysrq_reset_seq_len++] = (unsigned short)key;
727 }
728
729 /* Get reset timeout if any. */
730 of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms);
731}
732#else
733static void sysrq_of_get_keyreset_config(void)
734{
735}
736#endif
737
738static void sysrq_reinject_alt_sysrq(struct work_struct *work)
739{
740 struct sysrq_state *sysrq =
741 container_of(work, struct sysrq_state, reinject_work);
742 struct input_handle *handle = &sysrq->handle;
743 unsigned int alt_code = sysrq->alt_use;
744
745 if (sysrq->need_reinject) {
746 /* we do not want the assignment to be reordered */
747 sysrq->reinjecting = true;
748 mb();
749
750 /* Simulate press and release of Alt + SysRq */
751 input_inject_event(handle, EV_KEY, alt_code, 1);
752 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
753 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
754
755 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
756 input_inject_event(handle, EV_KEY, alt_code, 0);
757 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
758
759 mb();
760 sysrq->reinjecting = false;
761 }
762}
763
764static bool sysrq_handle_keypress(struct sysrq_state *sysrq,
765 unsigned int code, int value)
766{
767 bool was_active = sysrq->active;
768 bool suppress;
769
770 switch (code) {
771
772 case KEY_LEFTALT:
773 case KEY_RIGHTALT:
774 if (!value) {
775 /* One of ALTs is being released */
776 if (sysrq->active && code == sysrq->alt_use)
777 sysrq->active = false;
778
779 sysrq->alt = KEY_RESERVED;
780
781 } else if (value != 2) {
782 sysrq->alt = code;
783 sysrq->need_reinject = false;
784 }
785 break;
786
787 case KEY_SYSRQ:
788 if (value == 1 && sysrq->alt != KEY_RESERVED) {
789 sysrq->active = true;
790 sysrq->alt_use = sysrq->alt;
791 /*
792 * If nothing else will be pressed we'll need
793 * to re-inject Alt-SysRq keysroke.
794 */
795 sysrq->need_reinject = true;
796 }
797
798 /*
799 * Pretend that sysrq was never pressed at all. This
800 * is needed to properly handle KGDB which will try
801 * to release all keys after exiting debugger. If we
802 * do not clear key bit it KGDB will end up sending
803 * release events for Alt and SysRq, potentially
804 * triggering print screen function.
805 */
806 if (sysrq->active)
807 clear_bit(KEY_SYSRQ, sysrq->handle.dev->key);
808
809 break;
810
811 default:
812 if (sysrq->active && value && value != 2) {
813 sysrq->need_reinject = false;
814 __handle_sysrq(sysrq_xlate[code], true);
815 }
816 break;
817 }
818
819 suppress = sysrq->active;
820
821 if (!sysrq->active) {
822
823 /*
824 * See if reset sequence has changed since the last time.
825 */
826 if (sysrq->reset_seq_version != sysrq_reset_seq_version)
827 sysrq_parse_reset_sequence(sysrq);
828
829 /*
830 * If we are not suppressing key presses keep track of
831 * keyboard state so we can release keys that have been
832 * pressed before entering SysRq mode.
833 */
834 if (value)
835 set_bit(code, sysrq->key_down);
836 else
837 clear_bit(code, sysrq->key_down);
838
839 if (was_active)
840 schedule_work(&sysrq->reinject_work);
841
842 /* Check for reset sequence */
843 sysrq_detect_reset_sequence(sysrq, code, value);
844
845 } else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) {
846 /*
847 * Pass on release events for keys that was pressed before
848 * entering SysRq mode.
849 */
850 suppress = false;
851 }
852
853 return suppress;
854}
855
856static bool sysrq_filter(struct input_handle *handle,
857 unsigned int type, unsigned int code, int value)
858{
859 struct sysrq_state *sysrq = handle->private;
860 bool suppress;
861
862 /*
863 * Do not filter anything if we are in the process of re-injecting
864 * Alt+SysRq combination.
865 */
866 if (sysrq->reinjecting)
867 return false;
868
869 switch (type) {
870
871 case EV_SYN:
872 suppress = false;
873 break;
874
875 case EV_KEY:
876 suppress = sysrq_handle_keypress(sysrq, code, value);
877 break;
878
879 default:
880 suppress = sysrq->active;
881 break;
882 }
883
884 return suppress;
885}
886
887static int sysrq_connect(struct input_handler *handler,
888 struct input_dev *dev,
889 const struct input_device_id *id)
890{
891 struct sysrq_state *sysrq;
892 int error;
893
894 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);
895 if (!sysrq)
896 return -ENOMEM;
897
898 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
899
900 sysrq->handle.dev = dev;
901 sysrq->handle.handler = handler;
902 sysrq->handle.name = "sysrq";
903 sysrq->handle.private = sysrq;
904 setup_timer(&sysrq->keyreset_timer,
905 sysrq_do_reset, (unsigned long)sysrq);
906
907 error = input_register_handle(&sysrq->handle);
908 if (error) {
909 pr_err("Failed to register input sysrq handler, error %d\n",
910 error);
911 goto err_free;
912 }
913
914 error = input_open_device(&sysrq->handle);
915 if (error) {
916 pr_err("Failed to open input device, error %d\n", error);
917 goto err_unregister;
918 }
919
920 return 0;
921
922 err_unregister:
923 input_unregister_handle(&sysrq->handle);
924 err_free:
925 kfree(sysrq);
926 return error;
927}
928
929static void sysrq_disconnect(struct input_handle *handle)
930{
931 struct sysrq_state *sysrq = handle->private;
932
933 input_close_device(handle);
934 cancel_work_sync(&sysrq->reinject_work);
935 del_timer_sync(&sysrq->keyreset_timer);
936 input_unregister_handle(handle);
937 kfree(sysrq);
938}
939
940/*
941 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all
942 * keyboards have SysRq key predefined and so user may add it to keymap
943 * later, but we expect all such keyboards to have left alt.
944 */
945static const struct input_device_id sysrq_ids[] = {
946 {
947 .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
948 INPUT_DEVICE_ID_MATCH_KEYBIT,
949 .evbit = { [BIT_WORD(EV_KEY)] = BIT_MASK(EV_KEY) },
950 .keybit = { [BIT_WORD(KEY_LEFTALT)] = BIT_MASK(KEY_LEFTALT) },
951 },
952 { },
953};
954
955static struct input_handler sysrq_handler = {
956 .filter = sysrq_filter,
957 .connect = sysrq_connect,
958 .disconnect = sysrq_disconnect,
959 .name = "sysrq",
960 .id_table = sysrq_ids,
961};
962
963static bool sysrq_handler_registered;
964
965static inline void sysrq_register_handler(void)
966{
967 int error;
968
969 sysrq_of_get_keyreset_config();
970
971 error = input_register_handler(&sysrq_handler);
972 if (error)
973 pr_err("Failed to register input handler, error %d", error);
974 else
975 sysrq_handler_registered = true;
976}
977
978static inline void sysrq_unregister_handler(void)
979{
980 if (sysrq_handler_registered) {
981 input_unregister_handler(&sysrq_handler);
982 sysrq_handler_registered = false;
983 }
984}
985
986static int sysrq_reset_seq_param_set(const char *buffer,
987 const struct kernel_param *kp)
988{
989 unsigned long val;
990 int error;
991
992 error = kstrtoul(buffer, 0, &val);
993 if (error < 0)
994 return error;
995
996 if (val > KEY_MAX)
997 return -EINVAL;
998
999 *((unsigned short *)kp->arg) = val;
1000 sysrq_reset_seq_version++;
1001
1002 return 0;
1003}
1004
1005static const struct kernel_param_ops param_ops_sysrq_reset_seq = {
1006 .get = param_get_ushort,
1007 .set = sysrq_reset_seq_param_set,
1008};
1009
1010#define param_check_sysrq_reset_seq(name, p) \
1011 __param_check(name, p, unsigned short)
1012
1013/*
1014 * not really modular, but the easiest way to keep compat with existing
1015 * bootargs behaviour is to continue using module_param here.
1016 */
1017module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq,
1018 &sysrq_reset_seq_len, 0644);
1019
1020module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644);
1021
1022#else
1023
1024static inline void sysrq_register_handler(void)
1025{
1026}
1027
1028static inline void sysrq_unregister_handler(void)
1029{
1030}
1031
1032#endif /* CONFIG_INPUT */
1033
1034int sysrq_toggle_support(int enable_mask)
1035{
1036 bool was_enabled = sysrq_on();
1037
1038 sysrq_enabled = enable_mask;
1039
1040 if (was_enabled != sysrq_on()) {
1041 if (sysrq_on())
1042 sysrq_register_handler();
1043 else
1044 sysrq_unregister_handler();
1045 }
1046
1047 return 0;
1048}
1049
1050static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
1051 struct sysrq_key_op *remove_op_p)
1052{
1053 int retval;
1054
1055 spin_lock(&sysrq_key_table_lock);
1056 if (__sysrq_get_key_op(key) == remove_op_p) {
1057 __sysrq_put_key_op(key, insert_op_p);
1058 retval = 0;
1059 } else {
1060 retval = -1;
1061 }
1062 spin_unlock(&sysrq_key_table_lock);
1063
1064 /*
1065 * A concurrent __handle_sysrq either got the old op or the new op.
1066 * Wait for it to go away before returning, so the code for an old
1067 * op is not freed (eg. on module unload) while it is in use.
1068 */
1069 synchronize_rcu();
1070
1071 return retval;
1072}
1073
1074int register_sysrq_key(int key, struct sysrq_key_op *op_p)
1075{
1076 return __sysrq_swap_key_ops(key, op_p, NULL);
1077}
1078EXPORT_SYMBOL(register_sysrq_key);
1079
1080int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
1081{
1082 return __sysrq_swap_key_ops(key, NULL, op_p);
1083}
1084EXPORT_SYMBOL(unregister_sysrq_key);
1085
1086#ifdef CONFIG_PROC_FS
1087/*
1088 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
1089 */
1090static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
1091 size_t count, loff_t *ppos)
1092{
1093 if (count) {
1094 char c;
1095
1096 if (get_user(c, buf))
1097 return -EFAULT;
1098 __handle_sysrq(c, false);
1099 }
1100
1101 return count;
1102}
1103
1104static const struct file_operations proc_sysrq_trigger_operations = {
1105 .write = write_sysrq_trigger,
1106 .llseek = noop_llseek,
1107};
1108
1109static void sysrq_init_procfs(void)
1110{
1111 if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
1112 &proc_sysrq_trigger_operations))
1113 pr_err("Failed to register proc interface\n");
1114}
1115
1116#else
1117
1118static inline void sysrq_init_procfs(void)
1119{
1120}
1121
1122#endif /* CONFIG_PROC_FS */
1123
1124static int __init sysrq_init(void)
1125{
1126 sysrq_init_procfs();
1127
1128 if (sysrq_on())
1129 sysrq_register_handler();
1130
1131 return 0;
1132}
1133device_initcall(sysrq_init);