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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 /* release the RCU read lock before crashing */
138 rcu_read_unlock();
139
140 panic("sysrq triggered crash\n");
141}
142static struct sysrq_key_op sysrq_crash_op = {
143 .handler = sysrq_handle_crash,
144 .help_msg = "crash(c)",
145 .action_msg = "Trigger a crash",
146 .enable_mask = SYSRQ_ENABLE_DUMP,
147};
148
149static void sysrq_handle_reboot(int key)
150{
151 lockdep_off();
152 local_irq_enable();
153 emergency_restart();
154}
155static struct sysrq_key_op sysrq_reboot_op = {
156 .handler = sysrq_handle_reboot,
157 .help_msg = "reboot(b)",
158 .action_msg = "Resetting",
159 .enable_mask = SYSRQ_ENABLE_BOOT,
160};
161
162static void sysrq_handle_sync(int key)
163{
164 emergency_sync();
165}
166static struct sysrq_key_op sysrq_sync_op = {
167 .handler = sysrq_handle_sync,
168 .help_msg = "sync(s)",
169 .action_msg = "Emergency Sync",
170 .enable_mask = SYSRQ_ENABLE_SYNC,
171};
172
173static void sysrq_handle_show_timers(int key)
174{
175 sysrq_timer_list_show();
176}
177
178static struct sysrq_key_op sysrq_show_timers_op = {
179 .handler = sysrq_handle_show_timers,
180 .help_msg = "show-all-timers(q)",
181 .action_msg = "Show clockevent devices & pending hrtimers (no others)",
182};
183
184static void sysrq_handle_mountro(int key)
185{
186 emergency_remount();
187}
188static struct sysrq_key_op sysrq_mountro_op = {
189 .handler = sysrq_handle_mountro,
190 .help_msg = "unmount(u)",
191 .action_msg = "Emergency Remount R/O",
192 .enable_mask = SYSRQ_ENABLE_REMOUNT,
193};
194
195#ifdef CONFIG_LOCKDEP
196static void sysrq_handle_showlocks(int key)
197{
198 debug_show_all_locks();
199}
200
201static struct sysrq_key_op sysrq_showlocks_op = {
202 .handler = sysrq_handle_showlocks,
203 .help_msg = "show-all-locks(d)",
204 .action_msg = "Show Locks Held",
205};
206#else
207#define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL)
208#endif
209
210#ifdef CONFIG_SMP
211static DEFINE_RAW_SPINLOCK(show_lock);
212
213static void showacpu(void *dummy)
214{
215 unsigned long flags;
216
217 /* Idle CPUs have no interesting backtrace. */
218 if (idle_cpu(smp_processor_id()))
219 return;
220
221 raw_spin_lock_irqsave(&show_lock, flags);
222 pr_info("CPU%d:\n", smp_processor_id());
223 show_stack(NULL, NULL);
224 raw_spin_unlock_irqrestore(&show_lock, flags);
225}
226
227static void sysrq_showregs_othercpus(struct work_struct *dummy)
228{
229 smp_call_function(showacpu, NULL, 0);
230}
231
232static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
233
234static void sysrq_handle_showallcpus(int key)
235{
236 /*
237 * Fall back to the workqueue based printing if the
238 * backtrace printing did not succeed or the
239 * architecture has no support for it:
240 */
241 if (!trigger_all_cpu_backtrace()) {
242 struct pt_regs *regs = NULL;
243
244 if (in_irq())
245 regs = get_irq_regs();
246 if (regs) {
247 pr_info("CPU%d:\n", smp_processor_id());
248 show_regs(regs);
249 }
250 schedule_work(&sysrq_showallcpus);
251 }
252}
253
254static struct sysrq_key_op sysrq_showallcpus_op = {
255 .handler = sysrq_handle_showallcpus,
256 .help_msg = "show-backtrace-all-active-cpus(l)",
257 .action_msg = "Show backtrace of all active CPUs",
258 .enable_mask = SYSRQ_ENABLE_DUMP,
259};
260#endif
261
262static void sysrq_handle_showregs(int key)
263{
264 struct pt_regs *regs = NULL;
265
266 if (in_irq())
267 regs = get_irq_regs();
268 if (regs)
269 show_regs(regs);
270 perf_event_print_debug();
271}
272static struct sysrq_key_op sysrq_showregs_op = {
273 .handler = sysrq_handle_showregs,
274 .help_msg = "show-registers(p)",
275 .action_msg = "Show Regs",
276 .enable_mask = SYSRQ_ENABLE_DUMP,
277};
278
279static void sysrq_handle_showstate(int key)
280{
281 show_state();
282 show_workqueue_state();
283}
284static struct sysrq_key_op sysrq_showstate_op = {
285 .handler = sysrq_handle_showstate,
286 .help_msg = "show-task-states(t)",
287 .action_msg = "Show State",
288 .enable_mask = SYSRQ_ENABLE_DUMP,
289};
290
291static void sysrq_handle_showstate_blocked(int key)
292{
293 show_state_filter(TASK_UNINTERRUPTIBLE);
294}
295static struct sysrq_key_op sysrq_showstate_blocked_op = {
296 .handler = sysrq_handle_showstate_blocked,
297 .help_msg = "show-blocked-tasks(w)",
298 .action_msg = "Show Blocked State",
299 .enable_mask = SYSRQ_ENABLE_DUMP,
300};
301
302#ifdef CONFIG_TRACING
303#include <linux/ftrace.h>
304
305static void sysrq_ftrace_dump(int key)
306{
307 ftrace_dump(DUMP_ALL);
308}
309static struct sysrq_key_op sysrq_ftrace_dump_op = {
310 .handler = sysrq_ftrace_dump,
311 .help_msg = "dump-ftrace-buffer(z)",
312 .action_msg = "Dump ftrace buffer",
313 .enable_mask = SYSRQ_ENABLE_DUMP,
314};
315#else
316#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
317#endif
318
319static void sysrq_handle_showmem(int key)
320{
321 show_mem(0, NULL);
322}
323static struct sysrq_key_op sysrq_showmem_op = {
324 .handler = sysrq_handle_showmem,
325 .help_msg = "show-memory-usage(m)",
326 .action_msg = "Show Memory",
327 .enable_mask = SYSRQ_ENABLE_DUMP,
328};
329
330/*
331 * Signal sysrq helper function. Sends a signal to all user processes.
332 */
333static void send_sig_all(int sig)
334{
335 struct task_struct *p;
336
337 read_lock(&tasklist_lock);
338 for_each_process(p) {
339 if (p->flags & PF_KTHREAD)
340 continue;
341 if (is_global_init(p))
342 continue;
343
344 do_send_sig_info(sig, SEND_SIG_PRIV, p, PIDTYPE_MAX);
345 }
346 read_unlock(&tasklist_lock);
347}
348
349static void sysrq_handle_term(int key)
350{
351 send_sig_all(SIGTERM);
352 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
353}
354static struct sysrq_key_op sysrq_term_op = {
355 .handler = sysrq_handle_term,
356 .help_msg = "terminate-all-tasks(e)",
357 .action_msg = "Terminate All Tasks",
358 .enable_mask = SYSRQ_ENABLE_SIGNAL,
359};
360
361static void moom_callback(struct work_struct *ignored)
362{
363 const gfp_t gfp_mask = GFP_KERNEL;
364 struct oom_control oc = {
365 .zonelist = node_zonelist(first_memory_node, gfp_mask),
366 .nodemask = NULL,
367 .memcg = NULL,
368 .gfp_mask = gfp_mask,
369 .order = -1,
370 };
371
372 mutex_lock(&oom_lock);
373 if (!out_of_memory(&oc))
374 pr_info("OOM request ignored. No task eligible\n");
375 mutex_unlock(&oom_lock);
376}
377
378static DECLARE_WORK(moom_work, moom_callback);
379
380static void sysrq_handle_moom(int key)
381{
382 schedule_work(&moom_work);
383}
384static struct sysrq_key_op sysrq_moom_op = {
385 .handler = sysrq_handle_moom,
386 .help_msg = "memory-full-oom-kill(f)",
387 .action_msg = "Manual OOM execution",
388 .enable_mask = SYSRQ_ENABLE_SIGNAL,
389};
390
391#ifdef CONFIG_BLOCK
392static void sysrq_handle_thaw(int key)
393{
394 emergency_thaw_all();
395}
396static struct sysrq_key_op sysrq_thaw_op = {
397 .handler = sysrq_handle_thaw,
398 .help_msg = "thaw-filesystems(j)",
399 .action_msg = "Emergency Thaw of all frozen filesystems",
400 .enable_mask = SYSRQ_ENABLE_SIGNAL,
401};
402#endif
403
404static void sysrq_handle_kill(int key)
405{
406 send_sig_all(SIGKILL);
407 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
408}
409static struct sysrq_key_op sysrq_kill_op = {
410 .handler = sysrq_handle_kill,
411 .help_msg = "kill-all-tasks(i)",
412 .action_msg = "Kill All Tasks",
413 .enable_mask = SYSRQ_ENABLE_SIGNAL,
414};
415
416static void sysrq_handle_unrt(int key)
417{
418 normalize_rt_tasks();
419}
420static struct sysrq_key_op sysrq_unrt_op = {
421 .handler = sysrq_handle_unrt,
422 .help_msg = "nice-all-RT-tasks(n)",
423 .action_msg = "Nice All RT Tasks",
424 .enable_mask = SYSRQ_ENABLE_RTNICE,
425};
426
427/* Key Operations table and lock */
428static DEFINE_SPINLOCK(sysrq_key_table_lock);
429
430static struct sysrq_key_op *sysrq_key_table[36] = {
431 &sysrq_loglevel_op, /* 0 */
432 &sysrq_loglevel_op, /* 1 */
433 &sysrq_loglevel_op, /* 2 */
434 &sysrq_loglevel_op, /* 3 */
435 &sysrq_loglevel_op, /* 4 */
436 &sysrq_loglevel_op, /* 5 */
437 &sysrq_loglevel_op, /* 6 */
438 &sysrq_loglevel_op, /* 7 */
439 &sysrq_loglevel_op, /* 8 */
440 &sysrq_loglevel_op, /* 9 */
441
442 /*
443 * a: Don't use for system provided sysrqs, it is handled specially on
444 * sparc and will never arrive.
445 */
446 NULL, /* a */
447 &sysrq_reboot_op, /* b */
448 &sysrq_crash_op, /* c */
449 &sysrq_showlocks_op, /* d */
450 &sysrq_term_op, /* e */
451 &sysrq_moom_op, /* f */
452 /* g: May be registered for the kernel debugger */
453 NULL, /* g */
454 NULL, /* h - reserved for help */
455 &sysrq_kill_op, /* i */
456#ifdef CONFIG_BLOCK
457 &sysrq_thaw_op, /* j */
458#else
459 NULL, /* j */
460#endif
461 &sysrq_SAK_op, /* k */
462#ifdef CONFIG_SMP
463 &sysrq_showallcpus_op, /* l */
464#else
465 NULL, /* l */
466#endif
467 &sysrq_showmem_op, /* m */
468 &sysrq_unrt_op, /* n */
469 /* o: This will often be registered as 'Off' at init time */
470 NULL, /* o */
471 &sysrq_showregs_op, /* p */
472 &sysrq_show_timers_op, /* q */
473 &sysrq_unraw_op, /* r */
474 &sysrq_sync_op, /* s */
475 &sysrq_showstate_op, /* t */
476 &sysrq_mountro_op, /* u */
477 /* v: May be registered for frame buffer console restore */
478 NULL, /* v */
479 &sysrq_showstate_blocked_op, /* w */
480 /* x: May be registered on mips for TLB dump */
481 /* x: May be registered on ppc/powerpc for xmon */
482 /* x: May be registered on sparc64 for global PMU dump */
483 NULL, /* x */
484 /* y: May be registered on sparc64 for global register dump */
485 NULL, /* y */
486 &sysrq_ftrace_dump_op, /* z */
487};
488
489/* key2index calculation, -1 on invalid index */
490static int sysrq_key_table_key2index(int key)
491{
492 int retval;
493
494 if ((key >= '0') && (key <= '9'))
495 retval = key - '0';
496 else if ((key >= 'a') && (key <= 'z'))
497 retval = key + 10 - 'a';
498 else
499 retval = -1;
500 return retval;
501}
502
503/*
504 * get and put functions for the table, exposed to modules.
505 */
506struct sysrq_key_op *__sysrq_get_key_op(int key)
507{
508 struct sysrq_key_op *op_p = NULL;
509 int i;
510
511 i = sysrq_key_table_key2index(key);
512 if (i != -1)
513 op_p = sysrq_key_table[i];
514
515 return op_p;
516}
517
518static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
519{
520 int i = sysrq_key_table_key2index(key);
521
522 if (i != -1)
523 sysrq_key_table[i] = op_p;
524}
525
526void __handle_sysrq(int key, bool check_mask)
527{
528 struct sysrq_key_op *op_p;
529 int orig_log_level;
530 int orig_suppress_printk;
531 int i;
532
533 orig_suppress_printk = suppress_printk;
534 suppress_printk = 0;
535
536 rcu_sysrq_start();
537 rcu_read_lock();
538 /*
539 * Raise the apparent loglevel to maximum so that the sysrq header
540 * is shown to provide the user with positive feedback. We do not
541 * simply emit this at KERN_EMERG as that would change message
542 * routing in the consumers of /proc/kmsg.
543 */
544 orig_log_level = console_loglevel;
545 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
546
547 op_p = __sysrq_get_key_op(key);
548 if (op_p) {
549 /*
550 * Should we check for enabled operations (/proc/sysrq-trigger
551 * should not) and is the invoked operation enabled?
552 */
553 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
554 pr_info("%s\n", op_p->action_msg);
555 console_loglevel = orig_log_level;
556 op_p->handler(key);
557 } else {
558 pr_info("This sysrq operation is disabled.\n");
559 console_loglevel = orig_log_level;
560 }
561 } else {
562 pr_info("HELP : ");
563 /* Only print the help msg once per handler */
564 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
565 if (sysrq_key_table[i]) {
566 int j;
567
568 for (j = 0; sysrq_key_table[i] !=
569 sysrq_key_table[j]; j++)
570 ;
571 if (j != i)
572 continue;
573 pr_cont("%s ", sysrq_key_table[i]->help_msg);
574 }
575 }
576 pr_cont("\n");
577 console_loglevel = orig_log_level;
578 }
579 rcu_read_unlock();
580 rcu_sysrq_end();
581
582 suppress_printk = orig_suppress_printk;
583}
584
585void handle_sysrq(int key)
586{
587 if (sysrq_on())
588 __handle_sysrq(key, true);
589}
590EXPORT_SYMBOL(handle_sysrq);
591
592#ifdef CONFIG_INPUT
593static int sysrq_reset_downtime_ms;
594
595/* Simple translation table for the SysRq keys */
596static const unsigned char sysrq_xlate[KEY_CNT] =
597 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */
598 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */
599 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */
600 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */
601 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */
602 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
603 "\r\000/"; /* 0x60 - 0x6f */
604
605struct sysrq_state {
606 struct input_handle handle;
607 struct work_struct reinject_work;
608 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
609 unsigned int alt;
610 unsigned int alt_use;
611 bool active;
612 bool need_reinject;
613 bool reinjecting;
614
615 /* reset sequence handling */
616 bool reset_canceled;
617 bool reset_requested;
618 unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)];
619 int reset_seq_len;
620 int reset_seq_cnt;
621 int reset_seq_version;
622 struct timer_list keyreset_timer;
623};
624
625#define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */
626static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX];
627static unsigned int sysrq_reset_seq_len;
628static unsigned int sysrq_reset_seq_version = 1;
629
630static void sysrq_parse_reset_sequence(struct sysrq_state *state)
631{
632 int i;
633 unsigned short key;
634
635 state->reset_seq_cnt = 0;
636
637 for (i = 0; i < sysrq_reset_seq_len; i++) {
638 key = sysrq_reset_seq[i];
639
640 if (key == KEY_RESERVED || key > KEY_MAX)
641 break;
642
643 __set_bit(key, state->reset_keybit);
644 state->reset_seq_len++;
645
646 if (test_bit(key, state->key_down))
647 state->reset_seq_cnt++;
648 }
649
650 /* Disable reset until old keys are not released */
651 state->reset_canceled = state->reset_seq_cnt != 0;
652
653 state->reset_seq_version = sysrq_reset_seq_version;
654}
655
656static void sysrq_do_reset(struct timer_list *t)
657{
658 struct sysrq_state *state = from_timer(state, t, keyreset_timer);
659
660 state->reset_requested = true;
661
662 orderly_reboot();
663}
664
665static void sysrq_handle_reset_request(struct sysrq_state *state)
666{
667 if (state->reset_requested)
668 __handle_sysrq(sysrq_xlate[KEY_B], false);
669
670 if (sysrq_reset_downtime_ms)
671 mod_timer(&state->keyreset_timer,
672 jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms));
673 else
674 sysrq_do_reset(&state->keyreset_timer);
675}
676
677static void sysrq_detect_reset_sequence(struct sysrq_state *state,
678 unsigned int code, int value)
679{
680 if (!test_bit(code, state->reset_keybit)) {
681 /*
682 * Pressing any key _not_ in reset sequence cancels
683 * the reset sequence. Also cancelling the timer in
684 * case additional keys were pressed after a reset
685 * has been requested.
686 */
687 if (value && state->reset_seq_cnt) {
688 state->reset_canceled = true;
689 del_timer(&state->keyreset_timer);
690 }
691 } else if (value == 0) {
692 /*
693 * Key release - all keys in the reset sequence need
694 * to be pressed and held for the reset timeout
695 * to hold.
696 */
697 del_timer(&state->keyreset_timer);
698
699 if (--state->reset_seq_cnt == 0)
700 state->reset_canceled = false;
701 } else if (value == 1) {
702 /* key press, not autorepeat */
703 if (++state->reset_seq_cnt == state->reset_seq_len &&
704 !state->reset_canceled) {
705 sysrq_handle_reset_request(state);
706 }
707 }
708}
709
710#ifdef CONFIG_OF
711static void sysrq_of_get_keyreset_config(void)
712{
713 u32 key;
714 struct device_node *np;
715 struct property *prop;
716 const __be32 *p;
717
718 np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq");
719 if (!np) {
720 pr_debug("No sysrq node found");
721 return;
722 }
723
724 /* Reset in case a __weak definition was present */
725 sysrq_reset_seq_len = 0;
726
727 of_property_for_each_u32(np, "keyset", prop, p, key) {
728 if (key == KEY_RESERVED || key > KEY_MAX ||
729 sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX)
730 break;
731
732 sysrq_reset_seq[sysrq_reset_seq_len++] = (unsigned short)key;
733 }
734
735 /* Get reset timeout if any. */
736 of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms);
737
738 of_node_put(np);
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);
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/swap.h>
36#include <linux/spinlock.h>
37#include <linux/vt_kern.h>
38#include <linux/workqueue.h>
39#include <linux/hrtimer.h>
40#include <linux/oom.h>
41#include <linux/slab.h>
42#include <linux/input.h>
43#include <linux/uaccess.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 vt_reset_unicode(fg_console);
114}
115
116static struct sysrq_key_op sysrq_unraw_op = {
117 .handler = sysrq_handle_unraw,
118 .help_msg = "unRaw",
119 .action_msg = "Keyboard mode set to system default",
120 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
121};
122#else
123#define sysrq_unraw_op (*(struct sysrq_key_op *)NULL)
124#endif /* CONFIG_VT */
125
126static void sysrq_handle_crash(int key)
127{
128 char *killer = NULL;
129
130 panic_on_oops = 1; /* force panic */
131 wmb();
132 *killer = 1;
133}
134static struct sysrq_key_op sysrq_crash_op = {
135 .handler = sysrq_handle_crash,
136 .help_msg = "Crash",
137 .action_msg = "Trigger a crash",
138 .enable_mask = SYSRQ_ENABLE_DUMP,
139};
140
141static void sysrq_handle_reboot(int key)
142{
143 lockdep_off();
144 local_irq_enable();
145 emergency_restart();
146}
147static struct sysrq_key_op sysrq_reboot_op = {
148 .handler = sysrq_handle_reboot,
149 .help_msg = "reBoot",
150 .action_msg = "Resetting",
151 .enable_mask = SYSRQ_ENABLE_BOOT,
152};
153
154static void sysrq_handle_sync(int key)
155{
156 emergency_sync();
157}
158static struct sysrq_key_op sysrq_sync_op = {
159 .handler = sysrq_handle_sync,
160 .help_msg = "Sync",
161 .action_msg = "Emergency Sync",
162 .enable_mask = SYSRQ_ENABLE_SYNC,
163};
164
165static void sysrq_handle_show_timers(int key)
166{
167 sysrq_timer_list_show();
168}
169
170static struct sysrq_key_op sysrq_show_timers_op = {
171 .handler = sysrq_handle_show_timers,
172 .help_msg = "show-all-timers(Q)",
173 .action_msg = "Show clockevent devices & pending hrtimers (no others)",
174};
175
176static void sysrq_handle_mountro(int key)
177{
178 emergency_remount();
179}
180static struct sysrq_key_op sysrq_mountro_op = {
181 .handler = sysrq_handle_mountro,
182 .help_msg = "Unmount",
183 .action_msg = "Emergency Remount R/O",
184 .enable_mask = SYSRQ_ENABLE_REMOUNT,
185};
186
187#ifdef CONFIG_LOCKDEP
188static void sysrq_handle_showlocks(int key)
189{
190 debug_show_all_locks();
191}
192
193static struct sysrq_key_op sysrq_showlocks_op = {
194 .handler = sysrq_handle_showlocks,
195 .help_msg = "show-all-locks(D)",
196 .action_msg = "Show Locks Held",
197};
198#else
199#define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL)
200#endif
201
202#ifdef CONFIG_SMP
203static DEFINE_SPINLOCK(show_lock);
204
205static void showacpu(void *dummy)
206{
207 unsigned long flags;
208
209 /* Idle CPUs have no interesting backtrace. */
210 if (idle_cpu(smp_processor_id()))
211 return;
212
213 spin_lock_irqsave(&show_lock, flags);
214 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
215 show_stack(NULL, NULL);
216 spin_unlock_irqrestore(&show_lock, flags);
217}
218
219static void sysrq_showregs_othercpus(struct work_struct *dummy)
220{
221 smp_call_function(showacpu, NULL, 0);
222}
223
224static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
225
226static void sysrq_handle_showallcpus(int key)
227{
228 /*
229 * Fall back to the workqueue based printing if the
230 * backtrace printing did not succeed or the
231 * architecture has no support for it:
232 */
233 if (!trigger_all_cpu_backtrace()) {
234 struct pt_regs *regs = get_irq_regs();
235
236 if (regs) {
237 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
238 show_regs(regs);
239 }
240 schedule_work(&sysrq_showallcpus);
241 }
242}
243
244static struct sysrq_key_op sysrq_showallcpus_op = {
245 .handler = sysrq_handle_showallcpus,
246 .help_msg = "show-backtrace-all-active-cpus(L)",
247 .action_msg = "Show backtrace of all active CPUs",
248 .enable_mask = SYSRQ_ENABLE_DUMP,
249};
250#endif
251
252static void sysrq_handle_showregs(int key)
253{
254 struct pt_regs *regs = get_irq_regs();
255 if (regs)
256 show_regs(regs);
257 perf_event_print_debug();
258}
259static struct sysrq_key_op sysrq_showregs_op = {
260 .handler = sysrq_handle_showregs,
261 .help_msg = "show-registers(P)",
262 .action_msg = "Show Regs",
263 .enable_mask = SYSRQ_ENABLE_DUMP,
264};
265
266static void sysrq_handle_showstate(int key)
267{
268 show_state();
269}
270static struct sysrq_key_op sysrq_showstate_op = {
271 .handler = sysrq_handle_showstate,
272 .help_msg = "show-task-states(T)",
273 .action_msg = "Show State",
274 .enable_mask = SYSRQ_ENABLE_DUMP,
275};
276
277static void sysrq_handle_showstate_blocked(int key)
278{
279 show_state_filter(TASK_UNINTERRUPTIBLE);
280}
281static struct sysrq_key_op sysrq_showstate_blocked_op = {
282 .handler = sysrq_handle_showstate_blocked,
283 .help_msg = "show-blocked-tasks(W)",
284 .action_msg = "Show Blocked State",
285 .enable_mask = SYSRQ_ENABLE_DUMP,
286};
287
288#ifdef CONFIG_TRACING
289#include <linux/ftrace.h>
290
291static void sysrq_ftrace_dump(int key)
292{
293 ftrace_dump(DUMP_ALL);
294}
295static struct sysrq_key_op sysrq_ftrace_dump_op = {
296 .handler = sysrq_ftrace_dump,
297 .help_msg = "dump-ftrace-buffer(Z)",
298 .action_msg = "Dump ftrace buffer",
299 .enable_mask = SYSRQ_ENABLE_DUMP,
300};
301#else
302#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
303#endif
304
305static void sysrq_handle_showmem(int key)
306{
307 show_mem(0);
308}
309static struct sysrq_key_op sysrq_showmem_op = {
310 .handler = sysrq_handle_showmem,
311 .help_msg = "show-memory-usage(M)",
312 .action_msg = "Show Memory",
313 .enable_mask = SYSRQ_ENABLE_DUMP,
314};
315
316/*
317 * Signal sysrq helper function. Sends a signal to all user processes.
318 */
319static void send_sig_all(int sig)
320{
321 struct task_struct *p;
322
323 read_lock(&tasklist_lock);
324 for_each_process(p) {
325 if (p->flags & PF_KTHREAD)
326 continue;
327 if (is_global_init(p))
328 continue;
329
330 do_send_sig_info(sig, SEND_SIG_FORCED, p, true);
331 }
332 read_unlock(&tasklist_lock);
333}
334
335static void sysrq_handle_term(int key)
336{
337 send_sig_all(SIGTERM);
338 console_loglevel = 8;
339}
340static struct sysrq_key_op sysrq_term_op = {
341 .handler = sysrq_handle_term,
342 .help_msg = "terminate-all-tasks(E)",
343 .action_msg = "Terminate All Tasks",
344 .enable_mask = SYSRQ_ENABLE_SIGNAL,
345};
346
347static void moom_callback(struct work_struct *ignored)
348{
349 out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0, NULL, true);
350}
351
352static DECLARE_WORK(moom_work, moom_callback);
353
354static void sysrq_handle_moom(int key)
355{
356 schedule_work(&moom_work);
357}
358static struct sysrq_key_op sysrq_moom_op = {
359 .handler = sysrq_handle_moom,
360 .help_msg = "memory-full-oom-kill(F)",
361 .action_msg = "Manual OOM execution",
362 .enable_mask = SYSRQ_ENABLE_SIGNAL,
363};
364
365#ifdef CONFIG_BLOCK
366static void sysrq_handle_thaw(int key)
367{
368 emergency_thaw_all();
369}
370static struct sysrq_key_op sysrq_thaw_op = {
371 .handler = sysrq_handle_thaw,
372 .help_msg = "thaw-filesystems(J)",
373 .action_msg = "Emergency Thaw of all frozen filesystems",
374 .enable_mask = SYSRQ_ENABLE_SIGNAL,
375};
376#endif
377
378static void sysrq_handle_kill(int key)
379{
380 send_sig_all(SIGKILL);
381 console_loglevel = 8;
382}
383static struct sysrq_key_op sysrq_kill_op = {
384 .handler = sysrq_handle_kill,
385 .help_msg = "kill-all-tasks(I)",
386 .action_msg = "Kill All Tasks",
387 .enable_mask = SYSRQ_ENABLE_SIGNAL,
388};
389
390static void sysrq_handle_unrt(int key)
391{
392 normalize_rt_tasks();
393}
394static struct sysrq_key_op sysrq_unrt_op = {
395 .handler = sysrq_handle_unrt,
396 .help_msg = "nice-all-RT-tasks(N)",
397 .action_msg = "Nice All RT Tasks",
398 .enable_mask = SYSRQ_ENABLE_RTNICE,
399};
400
401/* Key Operations table and lock */
402static DEFINE_SPINLOCK(sysrq_key_table_lock);
403
404static struct sysrq_key_op *sysrq_key_table[36] = {
405 &sysrq_loglevel_op, /* 0 */
406 &sysrq_loglevel_op, /* 1 */
407 &sysrq_loglevel_op, /* 2 */
408 &sysrq_loglevel_op, /* 3 */
409 &sysrq_loglevel_op, /* 4 */
410 &sysrq_loglevel_op, /* 5 */
411 &sysrq_loglevel_op, /* 6 */
412 &sysrq_loglevel_op, /* 7 */
413 &sysrq_loglevel_op, /* 8 */
414 &sysrq_loglevel_op, /* 9 */
415
416 /*
417 * a: Don't use for system provided sysrqs, it is handled specially on
418 * sparc and will never arrive.
419 */
420 NULL, /* a */
421 &sysrq_reboot_op, /* b */
422 &sysrq_crash_op, /* c & ibm_emac driver debug */
423 &sysrq_showlocks_op, /* d */
424 &sysrq_term_op, /* e */
425 &sysrq_moom_op, /* f */
426 /* g: May be registered for the kernel debugger */
427 NULL, /* g */
428 NULL, /* h - reserved for help */
429 &sysrq_kill_op, /* i */
430#ifdef CONFIG_BLOCK
431 &sysrq_thaw_op, /* j */
432#else
433 NULL, /* j */
434#endif
435 &sysrq_SAK_op, /* k */
436#ifdef CONFIG_SMP
437 &sysrq_showallcpus_op, /* l */
438#else
439 NULL, /* l */
440#endif
441 &sysrq_showmem_op, /* m */
442 &sysrq_unrt_op, /* n */
443 /* o: This will often be registered as 'Off' at init time */
444 NULL, /* o */
445 &sysrq_showregs_op, /* p */
446 &sysrq_show_timers_op, /* q */
447 &sysrq_unraw_op, /* r */
448 &sysrq_sync_op, /* s */
449 &sysrq_showstate_op, /* t */
450 &sysrq_mountro_op, /* u */
451 /* v: May be registered for frame buffer console restore */
452 NULL, /* v */
453 &sysrq_showstate_blocked_op, /* w */
454 /* x: May be registered on ppc/powerpc for xmon */
455 NULL, /* x */
456 /* y: May be registered on sparc64 for global register dump */
457 NULL, /* y */
458 &sysrq_ftrace_dump_op, /* z */
459};
460
461/* key2index calculation, -1 on invalid index */
462static int sysrq_key_table_key2index(int key)
463{
464 int retval;
465
466 if ((key >= '0') && (key <= '9'))
467 retval = key - '0';
468 else if ((key >= 'a') && (key <= 'z'))
469 retval = key + 10 - 'a';
470 else
471 retval = -1;
472 return retval;
473}
474
475/*
476 * get and put functions for the table, exposed to modules.
477 */
478struct sysrq_key_op *__sysrq_get_key_op(int key)
479{
480 struct sysrq_key_op *op_p = NULL;
481 int i;
482
483 i = sysrq_key_table_key2index(key);
484 if (i != -1)
485 op_p = sysrq_key_table[i];
486
487 return op_p;
488}
489
490static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
491{
492 int i = sysrq_key_table_key2index(key);
493
494 if (i != -1)
495 sysrq_key_table[i] = op_p;
496}
497
498void __handle_sysrq(int key, bool check_mask)
499{
500 struct sysrq_key_op *op_p;
501 int orig_log_level;
502 int i;
503 unsigned long flags;
504
505 spin_lock_irqsave(&sysrq_key_table_lock, flags);
506 /*
507 * Raise the apparent loglevel to maximum so that the sysrq header
508 * is shown to provide the user with positive feedback. We do not
509 * simply emit this at KERN_EMERG as that would change message
510 * routing in the consumers of /proc/kmsg.
511 */
512 orig_log_level = console_loglevel;
513 console_loglevel = 7;
514 printk(KERN_INFO "SysRq : ");
515
516 op_p = __sysrq_get_key_op(key);
517 if (op_p) {
518 /*
519 * Should we check for enabled operations (/proc/sysrq-trigger
520 * should not) and is the invoked operation enabled?
521 */
522 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
523 printk("%s\n", op_p->action_msg);
524 console_loglevel = orig_log_level;
525 op_p->handler(key);
526 } else {
527 printk("This sysrq operation is disabled.\n");
528 }
529 } else {
530 printk("HELP : ");
531 /* Only print the help msg once per handler */
532 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
533 if (sysrq_key_table[i]) {
534 int j;
535
536 for (j = 0; sysrq_key_table[i] !=
537 sysrq_key_table[j]; j++)
538 ;
539 if (j != i)
540 continue;
541 printk("%s ", sysrq_key_table[i]->help_msg);
542 }
543 }
544 printk("\n");
545 console_loglevel = orig_log_level;
546 }
547 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
548}
549
550void handle_sysrq(int key)
551{
552 if (sysrq_on())
553 __handle_sysrq(key, true);
554}
555EXPORT_SYMBOL(handle_sysrq);
556
557#ifdef CONFIG_INPUT
558
559/* Simple translation table for the SysRq keys */
560static const unsigned char sysrq_xlate[KEY_CNT] =
561 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */
562 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */
563 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */
564 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */
565 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */
566 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
567 "\r\000/"; /* 0x60 - 0x6f */
568
569struct sysrq_state {
570 struct input_handle handle;
571 struct work_struct reinject_work;
572 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
573 unsigned int alt;
574 unsigned int alt_use;
575 bool active;
576 bool need_reinject;
577 bool reinjecting;
578};
579
580static void sysrq_reinject_alt_sysrq(struct work_struct *work)
581{
582 struct sysrq_state *sysrq =
583 container_of(work, struct sysrq_state, reinject_work);
584 struct input_handle *handle = &sysrq->handle;
585 unsigned int alt_code = sysrq->alt_use;
586
587 if (sysrq->need_reinject) {
588 /* we do not want the assignment to be reordered */
589 sysrq->reinjecting = true;
590 mb();
591
592 /* Simulate press and release of Alt + SysRq */
593 input_inject_event(handle, EV_KEY, alt_code, 1);
594 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
595 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
596
597 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
598 input_inject_event(handle, EV_KEY, alt_code, 0);
599 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
600
601 mb();
602 sysrq->reinjecting = false;
603 }
604}
605
606static bool sysrq_filter(struct input_handle *handle,
607 unsigned int type, unsigned int code, int value)
608{
609 struct sysrq_state *sysrq = handle->private;
610 bool was_active = sysrq->active;
611 bool suppress;
612
613 /*
614 * Do not filter anything if we are in the process of re-injecting
615 * Alt+SysRq combination.
616 */
617 if (sysrq->reinjecting)
618 return false;
619
620 switch (type) {
621
622 case EV_SYN:
623 suppress = false;
624 break;
625
626 case EV_KEY:
627 switch (code) {
628
629 case KEY_LEFTALT:
630 case KEY_RIGHTALT:
631 if (!value) {
632 /* One of ALTs is being released */
633 if (sysrq->active && code == sysrq->alt_use)
634 sysrq->active = false;
635
636 sysrq->alt = KEY_RESERVED;
637
638 } else if (value != 2) {
639 sysrq->alt = code;
640 sysrq->need_reinject = false;
641 }
642 break;
643
644 case KEY_SYSRQ:
645 if (value == 1 && sysrq->alt != KEY_RESERVED) {
646 sysrq->active = true;
647 sysrq->alt_use = sysrq->alt;
648 /*
649 * If nothing else will be pressed we'll need
650 * to re-inject Alt-SysRq keysroke.
651 */
652 sysrq->need_reinject = true;
653 }
654
655 /*
656 * Pretend that sysrq was never pressed at all. This
657 * is needed to properly handle KGDB which will try
658 * to release all keys after exiting debugger. If we
659 * do not clear key bit it KGDB will end up sending
660 * release events for Alt and SysRq, potentially
661 * triggering print screen function.
662 */
663 if (sysrq->active)
664 clear_bit(KEY_SYSRQ, handle->dev->key);
665
666 break;
667
668 default:
669 if (sysrq->active && value && value != 2) {
670 sysrq->need_reinject = false;
671 __handle_sysrq(sysrq_xlate[code], true);
672 }
673 break;
674 }
675
676 suppress = sysrq->active;
677
678 if (!sysrq->active) {
679 /*
680 * If we are not suppressing key presses keep track of
681 * keyboard state so we can release keys that have been
682 * pressed before entering SysRq mode.
683 */
684 if (value)
685 set_bit(code, sysrq->key_down);
686 else
687 clear_bit(code, sysrq->key_down);
688
689 if (was_active)
690 schedule_work(&sysrq->reinject_work);
691
692 } else if (value == 0 &&
693 test_and_clear_bit(code, sysrq->key_down)) {
694 /*
695 * Pass on release events for keys that was pressed before
696 * entering SysRq mode.
697 */
698 suppress = false;
699 }
700 break;
701
702 default:
703 suppress = sysrq->active;
704 break;
705 }
706
707 return suppress;
708}
709
710static int sysrq_connect(struct input_handler *handler,
711 struct input_dev *dev,
712 const struct input_device_id *id)
713{
714 struct sysrq_state *sysrq;
715 int error;
716
717 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);
718 if (!sysrq)
719 return -ENOMEM;
720
721 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
722
723 sysrq->handle.dev = dev;
724 sysrq->handle.handler = handler;
725 sysrq->handle.name = "sysrq";
726 sysrq->handle.private = sysrq;
727
728 error = input_register_handle(&sysrq->handle);
729 if (error) {
730 pr_err("Failed to register input sysrq handler, error %d\n",
731 error);
732 goto err_free;
733 }
734
735 error = input_open_device(&sysrq->handle);
736 if (error) {
737 pr_err("Failed to open input device, error %d\n", error);
738 goto err_unregister;
739 }
740
741 return 0;
742
743 err_unregister:
744 input_unregister_handle(&sysrq->handle);
745 err_free:
746 kfree(sysrq);
747 return error;
748}
749
750static void sysrq_disconnect(struct input_handle *handle)
751{
752 struct sysrq_state *sysrq = handle->private;
753
754 input_close_device(handle);
755 cancel_work_sync(&sysrq->reinject_work);
756 input_unregister_handle(handle);
757 kfree(sysrq);
758}
759
760/*
761 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all
762 * keyboards have SysRq key predefined and so user may add it to keymap
763 * later, but we expect all such keyboards to have left alt.
764 */
765static const struct input_device_id sysrq_ids[] = {
766 {
767 .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
768 INPUT_DEVICE_ID_MATCH_KEYBIT,
769 .evbit = { BIT_MASK(EV_KEY) },
770 .keybit = { BIT_MASK(KEY_LEFTALT) },
771 },
772 { },
773};
774
775static struct input_handler sysrq_handler = {
776 .filter = sysrq_filter,
777 .connect = sysrq_connect,
778 .disconnect = sysrq_disconnect,
779 .name = "sysrq",
780 .id_table = sysrq_ids,
781};
782
783static bool sysrq_handler_registered;
784
785static inline void sysrq_register_handler(void)
786{
787 int error;
788
789 error = input_register_handler(&sysrq_handler);
790 if (error)
791 pr_err("Failed to register input handler, error %d", error);
792 else
793 sysrq_handler_registered = true;
794}
795
796static inline void sysrq_unregister_handler(void)
797{
798 if (sysrq_handler_registered) {
799 input_unregister_handler(&sysrq_handler);
800 sysrq_handler_registered = false;
801 }
802}
803
804#else
805
806static inline void sysrq_register_handler(void)
807{
808}
809
810static inline void sysrq_unregister_handler(void)
811{
812}
813
814#endif /* CONFIG_INPUT */
815
816int sysrq_toggle_support(int enable_mask)
817{
818 bool was_enabled = sysrq_on();
819
820 sysrq_enabled = enable_mask;
821
822 if (was_enabled != sysrq_on()) {
823 if (sysrq_on())
824 sysrq_register_handler();
825 else
826 sysrq_unregister_handler();
827 }
828
829 return 0;
830}
831
832static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
833 struct sysrq_key_op *remove_op_p)
834{
835 int retval;
836 unsigned long flags;
837
838 spin_lock_irqsave(&sysrq_key_table_lock, flags);
839 if (__sysrq_get_key_op(key) == remove_op_p) {
840 __sysrq_put_key_op(key, insert_op_p);
841 retval = 0;
842 } else {
843 retval = -1;
844 }
845 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
846 return retval;
847}
848
849int register_sysrq_key(int key, struct sysrq_key_op *op_p)
850{
851 return __sysrq_swap_key_ops(key, op_p, NULL);
852}
853EXPORT_SYMBOL(register_sysrq_key);
854
855int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
856{
857 return __sysrq_swap_key_ops(key, NULL, op_p);
858}
859EXPORT_SYMBOL(unregister_sysrq_key);
860
861#ifdef CONFIG_PROC_FS
862/*
863 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
864 */
865static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
866 size_t count, loff_t *ppos)
867{
868 if (count) {
869 char c;
870
871 if (get_user(c, buf))
872 return -EFAULT;
873 __handle_sysrq(c, false);
874 }
875
876 return count;
877}
878
879static const struct file_operations proc_sysrq_trigger_operations = {
880 .write = write_sysrq_trigger,
881 .llseek = noop_llseek,
882};
883
884static void sysrq_init_procfs(void)
885{
886 if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
887 &proc_sysrq_trigger_operations))
888 pr_err("Failed to register proc interface\n");
889}
890
891#else
892
893static inline void sysrq_init_procfs(void)
894{
895}
896
897#endif /* CONFIG_PROC_FS */
898
899static int __init sysrq_init(void)
900{
901 sysrq_init_procfs();
902
903 if (sysrq_on())
904 sysrq_register_handler();
905
906 return 0;
907}
908module_init(sysrq_init);