Line data Source code
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/ctype.h>
23 : #include <linux/interrupt.h>
24 : #include <linux/mm.h>
25 : #include <linux/fs.h>
26 : #include <linux/mount.h>
27 : #include <linux/kdev_t.h>
28 : #include <linux/major.h>
29 : #include <linux/reboot.h>
30 : #include <linux/sysrq.h>
31 : #include <linux/kbd_kern.h>
32 : #include <linux/proc_fs.h>
33 : #include <linux/nmi.h>
34 : #include <linux/quotaops.h>
35 : #include <linux/perf_event.h>
36 : #include <linux/kernel.h>
37 : #include <linux/module.h>
38 : #include <linux/suspend.h>
39 : #include <linux/writeback.h>
40 : #include <linux/swap.h>
41 : #include <linux/spinlock.h>
42 : #include <linux/vt_kern.h>
43 : #include <linux/workqueue.h>
44 : #include <linux/hrtimer.h>
45 : #include <linux/oom.h>
46 : #include <linux/slab.h>
47 : #include <linux/input.h>
48 : #include <linux/uaccess.h>
49 : #include <linux/moduleparam.h>
50 : #include <linux/jiffies.h>
51 : #include <linux/syscalls.h>
52 : #include <linux/of.h>
53 : #include <linux/rcupdate.h>
54 :
55 : #include <asm/ptrace.h>
56 : #include <asm/irq_regs.h>
57 :
58 : /* Whether we react on sysrq keys or just ignore them */
59 : static int __read_mostly sysrq_enabled = CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE;
60 : static bool __read_mostly sysrq_always_enabled;
61 :
62 1 : static bool sysrq_on(void)
63 : {
64 0 : return sysrq_enabled || sysrq_always_enabled;
65 : }
66 :
67 : /**
68 : * sysrq_mask - Getter for sysrq_enabled mask.
69 : *
70 : * Return: 1 if sysrq is always enabled, enabled sysrq_key_op mask otherwise.
71 : */
72 0 : int sysrq_mask(void)
73 : {
74 0 : if (sysrq_always_enabled)
75 : return 1;
76 0 : return sysrq_enabled;
77 : }
78 : EXPORT_SYMBOL_GPL(sysrq_mask);
79 :
80 : /*
81 : * A value of 1 means 'all', other nonzero values are an op mask:
82 : */
83 0 : static bool sysrq_on_mask(int mask)
84 : {
85 0 : return sysrq_always_enabled ||
86 0 : sysrq_enabled == 1 ||
87 0 : (sysrq_enabled & mask);
88 : }
89 :
90 0 : static int __init sysrq_always_enabled_setup(char *str)
91 : {
92 0 : sysrq_always_enabled = true;
93 0 : pr_info("sysrq always enabled.\n");
94 :
95 0 : return 1;
96 : }
97 :
98 : __setup("sysrq_always_enabled", sysrq_always_enabled_setup);
99 :
100 :
101 0 : static void sysrq_handle_loglevel(int key)
102 : {
103 0 : int i;
104 :
105 0 : i = key - '0';
106 0 : console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
107 0 : pr_info("Loglevel set to %d\n", i);
108 0 : console_loglevel = i;
109 0 : }
110 : static const struct sysrq_key_op sysrq_loglevel_op = {
111 : .handler = sysrq_handle_loglevel,
112 : .help_msg = "loglevel(0-9)",
113 : .action_msg = "Changing Loglevel",
114 : .enable_mask = SYSRQ_ENABLE_LOG,
115 : };
116 :
117 : #ifdef CONFIG_VT
118 0 : static void sysrq_handle_SAK(int key)
119 : {
120 0 : struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
121 0 : schedule_work(SAK_work);
122 0 : }
123 : static const struct sysrq_key_op sysrq_SAK_op = {
124 : .handler = sysrq_handle_SAK,
125 : .help_msg = "sak(k)",
126 : .action_msg = "SAK",
127 : .enable_mask = SYSRQ_ENABLE_KEYBOARD,
128 : };
129 : #else
130 : #define sysrq_SAK_op (*(const struct sysrq_key_op *)NULL)
131 : #endif
132 :
133 : #ifdef CONFIG_VT
134 0 : static void sysrq_handle_unraw(int key)
135 : {
136 0 : vt_reset_unicode(fg_console);
137 0 : }
138 :
139 : static const struct sysrq_key_op sysrq_unraw_op = {
140 : .handler = sysrq_handle_unraw,
141 : .help_msg = "unraw(r)",
142 : .action_msg = "Keyboard mode set to system default",
143 : .enable_mask = SYSRQ_ENABLE_KEYBOARD,
144 : };
145 : #else
146 : #define sysrq_unraw_op (*(const struct sysrq_key_op *)NULL)
147 : #endif /* CONFIG_VT */
148 :
149 0 : static void sysrq_handle_crash(int key)
150 : {
151 : /* release the RCU read lock before crashing */
152 0 : rcu_read_unlock();
153 :
154 0 : panic("sysrq triggered crash\n");
155 : }
156 : static const struct sysrq_key_op sysrq_crash_op = {
157 : .handler = sysrq_handle_crash,
158 : .help_msg = "crash(c)",
159 : .action_msg = "Trigger a crash",
160 : .enable_mask = SYSRQ_ENABLE_DUMP,
161 : };
162 :
163 0 : static void sysrq_handle_reboot(int key)
164 : {
165 0 : lockdep_off();
166 0 : local_irq_enable();
167 0 : emergency_restart();
168 0 : }
169 : static const struct sysrq_key_op sysrq_reboot_op = {
170 : .handler = sysrq_handle_reboot,
171 : .help_msg = "reboot(b)",
172 : .action_msg = "Resetting",
173 : .enable_mask = SYSRQ_ENABLE_BOOT,
174 : };
175 :
176 : const struct sysrq_key_op *__sysrq_reboot_op = &sysrq_reboot_op;
177 :
178 0 : static void sysrq_handle_sync(int key)
179 : {
180 0 : emergency_sync();
181 0 : }
182 : static const struct sysrq_key_op sysrq_sync_op = {
183 : .handler = sysrq_handle_sync,
184 : .help_msg = "sync(s)",
185 : .action_msg = "Emergency Sync",
186 : .enable_mask = SYSRQ_ENABLE_SYNC,
187 : };
188 :
189 0 : static void sysrq_handle_show_timers(int key)
190 : {
191 0 : sysrq_timer_list_show();
192 0 : }
193 :
194 : static const struct sysrq_key_op sysrq_show_timers_op = {
195 : .handler = sysrq_handle_show_timers,
196 : .help_msg = "show-all-timers(q)",
197 : .action_msg = "Show clockevent devices & pending hrtimers (no others)",
198 : };
199 :
200 0 : static void sysrq_handle_mountro(int key)
201 : {
202 0 : emergency_remount();
203 0 : }
204 : static const struct sysrq_key_op sysrq_mountro_op = {
205 : .handler = sysrq_handle_mountro,
206 : .help_msg = "unmount(u)",
207 : .action_msg = "Emergency Remount R/O",
208 : .enable_mask = SYSRQ_ENABLE_REMOUNT,
209 : };
210 :
211 : #ifdef CONFIG_LOCKDEP
212 0 : static void sysrq_handle_showlocks(int key)
213 : {
214 0 : debug_show_all_locks();
215 0 : }
216 :
217 : static const struct sysrq_key_op sysrq_showlocks_op = {
218 : .handler = sysrq_handle_showlocks,
219 : .help_msg = "show-all-locks(d)",
220 : .action_msg = "Show Locks Held",
221 : };
222 : #else
223 : #define sysrq_showlocks_op (*(const struct sysrq_key_op *)NULL)
224 : #endif
225 :
226 : #ifdef CONFIG_SMP
227 : static DEFINE_RAW_SPINLOCK(show_lock);
228 :
229 : static void showacpu(void *dummy)
230 : {
231 : unsigned long flags;
232 :
233 : /* Idle CPUs have no interesting backtrace. */
234 : if (idle_cpu(smp_processor_id()))
235 : return;
236 :
237 : raw_spin_lock_irqsave(&show_lock, flags);
238 : pr_info("CPU%d:\n", smp_processor_id());
239 : show_stack(NULL, NULL, KERN_INFO);
240 : raw_spin_unlock_irqrestore(&show_lock, flags);
241 : }
242 :
243 : static void sysrq_showregs_othercpus(struct work_struct *dummy)
244 : {
245 : smp_call_function(showacpu, NULL, 0);
246 : }
247 :
248 : static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
249 :
250 0 : static void sysrq_handle_showallcpus(int key)
251 : {
252 : /*
253 : * Fall back to the workqueue based printing if the
254 : * backtrace printing did not succeed or the
255 : * architecture has no support for it:
256 : */
257 0 : if (!trigger_all_cpu_backtrace()) {
258 : struct pt_regs *regs = NULL;
259 :
260 : if (in_irq())
261 : regs = get_irq_regs();
262 : if (regs) {
263 : pr_info("CPU%d:\n", smp_processor_id());
264 : show_regs(regs);
265 : }
266 : schedule_work(&sysrq_showallcpus);
267 : }
268 0 : }
269 :
270 : static const struct sysrq_key_op sysrq_showallcpus_op = {
271 : .handler = sysrq_handle_showallcpus,
272 : .help_msg = "show-backtrace-all-active-cpus(l)",
273 : .action_msg = "Show backtrace of all active CPUs",
274 : .enable_mask = SYSRQ_ENABLE_DUMP,
275 : };
276 : #endif
277 :
278 0 : static void sysrq_handle_showregs(int key)
279 : {
280 0 : struct pt_regs *regs = NULL;
281 :
282 0 : if (in_irq())
283 0 : regs = get_irq_regs();
284 0 : if (regs)
285 0 : show_regs(regs);
286 0 : perf_event_print_debug();
287 0 : }
288 : static const struct sysrq_key_op sysrq_showregs_op = {
289 : .handler = sysrq_handle_showregs,
290 : .help_msg = "show-registers(p)",
291 : .action_msg = "Show Regs",
292 : .enable_mask = SYSRQ_ENABLE_DUMP,
293 : };
294 :
295 0 : static void sysrq_handle_showstate(int key)
296 : {
297 0 : show_state();
298 0 : show_workqueue_state();
299 0 : }
300 : static const struct sysrq_key_op sysrq_showstate_op = {
301 : .handler = sysrq_handle_showstate,
302 : .help_msg = "show-task-states(t)",
303 : .action_msg = "Show State",
304 : .enable_mask = SYSRQ_ENABLE_DUMP,
305 : };
306 :
307 0 : static void sysrq_handle_showstate_blocked(int key)
308 : {
309 0 : show_state_filter(TASK_UNINTERRUPTIBLE);
310 0 : }
311 : static const struct sysrq_key_op sysrq_showstate_blocked_op = {
312 : .handler = sysrq_handle_showstate_blocked,
313 : .help_msg = "show-blocked-tasks(w)",
314 : .action_msg = "Show Blocked State",
315 : .enable_mask = SYSRQ_ENABLE_DUMP,
316 : };
317 :
318 : #ifdef CONFIG_TRACING
319 : #include <linux/ftrace.h>
320 :
321 0 : static void sysrq_ftrace_dump(int key)
322 : {
323 0 : ftrace_dump(DUMP_ALL);
324 0 : }
325 : static const struct sysrq_key_op sysrq_ftrace_dump_op = {
326 : .handler = sysrq_ftrace_dump,
327 : .help_msg = "dump-ftrace-buffer(z)",
328 : .action_msg = "Dump ftrace buffer",
329 : .enable_mask = SYSRQ_ENABLE_DUMP,
330 : };
331 : #else
332 : #define sysrq_ftrace_dump_op (*(const struct sysrq_key_op *)NULL)
333 : #endif
334 :
335 0 : static void sysrq_handle_showmem(int key)
336 : {
337 0 : show_mem(0, NULL);
338 0 : }
339 : static const struct sysrq_key_op sysrq_showmem_op = {
340 : .handler = sysrq_handle_showmem,
341 : .help_msg = "show-memory-usage(m)",
342 : .action_msg = "Show Memory",
343 : .enable_mask = SYSRQ_ENABLE_DUMP,
344 : };
345 :
346 : /*
347 : * Signal sysrq helper function. Sends a signal to all user processes.
348 : */
349 0 : static void send_sig_all(int sig)
350 : {
351 0 : struct task_struct *p;
352 :
353 0 : read_lock(&tasklist_lock);
354 0 : for_each_process(p) {
355 0 : if (p->flags & PF_KTHREAD)
356 0 : continue;
357 0 : if (is_global_init(p))
358 0 : continue;
359 :
360 0 : do_send_sig_info(sig, SEND_SIG_PRIV, p, PIDTYPE_MAX);
361 : }
362 0 : read_unlock(&tasklist_lock);
363 0 : }
364 :
365 0 : static void sysrq_handle_term(int key)
366 : {
367 0 : send_sig_all(SIGTERM);
368 0 : console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
369 0 : }
370 : static const struct sysrq_key_op sysrq_term_op = {
371 : .handler = sysrq_handle_term,
372 : .help_msg = "terminate-all-tasks(e)",
373 : .action_msg = "Terminate All Tasks",
374 : .enable_mask = SYSRQ_ENABLE_SIGNAL,
375 : };
376 :
377 0 : static void moom_callback(struct work_struct *ignored)
378 : {
379 0 : const gfp_t gfp_mask = GFP_KERNEL;
380 0 : struct oom_control oc = {
381 0 : .zonelist = node_zonelist(first_memory_node, gfp_mask),
382 : .nodemask = NULL,
383 : .memcg = NULL,
384 : .gfp_mask = gfp_mask,
385 : .order = -1,
386 : };
387 :
388 0 : mutex_lock(&oom_lock);
389 0 : if (!out_of_memory(&oc))
390 0 : pr_info("OOM request ignored. No task eligible\n");
391 0 : mutex_unlock(&oom_lock);
392 0 : }
393 :
394 : static DECLARE_WORK(moom_work, moom_callback);
395 :
396 0 : static void sysrq_handle_moom(int key)
397 : {
398 0 : schedule_work(&moom_work);
399 0 : }
400 : static const struct sysrq_key_op sysrq_moom_op = {
401 : .handler = sysrq_handle_moom,
402 : .help_msg = "memory-full-oom-kill(f)",
403 : .action_msg = "Manual OOM execution",
404 : .enable_mask = SYSRQ_ENABLE_SIGNAL,
405 : };
406 :
407 0 : static void sysrq_handle_thaw(int key)
408 : {
409 0 : emergency_thaw_all();
410 0 : }
411 : static const struct sysrq_key_op sysrq_thaw_op = {
412 : .handler = sysrq_handle_thaw,
413 : .help_msg = "thaw-filesystems(j)",
414 : .action_msg = "Emergency Thaw of all frozen filesystems",
415 : .enable_mask = SYSRQ_ENABLE_SIGNAL,
416 : };
417 :
418 0 : static void sysrq_handle_kill(int key)
419 : {
420 0 : send_sig_all(SIGKILL);
421 0 : console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
422 0 : }
423 : static const struct sysrq_key_op sysrq_kill_op = {
424 : .handler = sysrq_handle_kill,
425 : .help_msg = "kill-all-tasks(i)",
426 : .action_msg = "Kill All Tasks",
427 : .enable_mask = SYSRQ_ENABLE_SIGNAL,
428 : };
429 :
430 0 : static void sysrq_handle_unrt(int key)
431 : {
432 0 : normalize_rt_tasks();
433 0 : }
434 : static const struct sysrq_key_op sysrq_unrt_op = {
435 : .handler = sysrq_handle_unrt,
436 : .help_msg = "nice-all-RT-tasks(n)",
437 : .action_msg = "Nice All RT Tasks",
438 : .enable_mask = SYSRQ_ENABLE_RTNICE,
439 : };
440 :
441 : /* Key Operations table and lock */
442 : static DEFINE_SPINLOCK(sysrq_key_table_lock);
443 :
444 : static const struct sysrq_key_op *sysrq_key_table[62] = {
445 : &sysrq_loglevel_op, /* 0 */
446 : &sysrq_loglevel_op, /* 1 */
447 : &sysrq_loglevel_op, /* 2 */
448 : &sysrq_loglevel_op, /* 3 */
449 : &sysrq_loglevel_op, /* 4 */
450 : &sysrq_loglevel_op, /* 5 */
451 : &sysrq_loglevel_op, /* 6 */
452 : &sysrq_loglevel_op, /* 7 */
453 : &sysrq_loglevel_op, /* 8 */
454 : &sysrq_loglevel_op, /* 9 */
455 :
456 : /*
457 : * a: Don't use for system provided sysrqs, it is handled specially on
458 : * sparc and will never arrive.
459 : */
460 : NULL, /* a */
461 : &sysrq_reboot_op, /* b */
462 : &sysrq_crash_op, /* c */
463 : &sysrq_showlocks_op, /* d */
464 : &sysrq_term_op, /* e */
465 : &sysrq_moom_op, /* f */
466 : /* g: May be registered for the kernel debugger */
467 : NULL, /* g */
468 : NULL, /* h - reserved for help */
469 : &sysrq_kill_op, /* i */
470 : #ifdef CONFIG_BLOCK
471 : &sysrq_thaw_op, /* j */
472 : #else
473 : NULL, /* j */
474 : #endif
475 : &sysrq_SAK_op, /* k */
476 : #ifdef CONFIG_SMP
477 : &sysrq_showallcpus_op, /* l */
478 : #else
479 : NULL, /* l */
480 : #endif
481 : &sysrq_showmem_op, /* m */
482 : &sysrq_unrt_op, /* n */
483 : /* o: This will often be registered as 'Off' at init time */
484 : NULL, /* o */
485 : &sysrq_showregs_op, /* p */
486 : &sysrq_show_timers_op, /* q */
487 : &sysrq_unraw_op, /* r */
488 : &sysrq_sync_op, /* s */
489 : &sysrq_showstate_op, /* t */
490 : &sysrq_mountro_op, /* u */
491 : /* v: May be registered for frame buffer console restore */
492 : NULL, /* v */
493 : &sysrq_showstate_blocked_op, /* w */
494 : /* x: May be registered on mips for TLB dump */
495 : /* x: May be registered on ppc/powerpc for xmon */
496 : /* x: May be registered on sparc64 for global PMU dump */
497 : NULL, /* x */
498 : /* y: May be registered on sparc64 for global register dump */
499 : NULL, /* y */
500 : &sysrq_ftrace_dump_op, /* z */
501 : NULL, /* A */
502 : NULL, /* B */
503 : NULL, /* C */
504 : NULL, /* D */
505 : NULL, /* E */
506 : NULL, /* F */
507 : NULL, /* G */
508 : NULL, /* H */
509 : NULL, /* I */
510 : NULL, /* J */
511 : NULL, /* K */
512 : NULL, /* L */
513 : NULL, /* M */
514 : NULL, /* N */
515 : NULL, /* O */
516 : NULL, /* P */
517 : NULL, /* Q */
518 : NULL, /* R */
519 : NULL, /* S */
520 : NULL, /* T */
521 : NULL, /* U */
522 : NULL, /* V */
523 : NULL, /* W */
524 : NULL, /* X */
525 : NULL, /* Y */
526 : NULL, /* Z */
527 : };
528 :
529 : /* key2index calculation, -1 on invalid index */
530 2 : static int sysrq_key_table_key2index(int key)
531 : {
532 2 : int retval;
533 :
534 2 : if ((key >= '0') && (key <= '9'))
535 0 : retval = key - '0';
536 2 : else if ((key >= 'a') && (key <= 'z'))
537 2 : retval = key + 10 - 'a';
538 0 : else if ((key >= 'A') && (key <= 'Z'))
539 0 : retval = key + 36 - 'A';
540 : else
541 : retval = -1;
542 2 : return retval;
543 : }
544 :
545 : /*
546 : * get and put functions for the table, exposed to modules.
547 : */
548 1 : static const struct sysrq_key_op *__sysrq_get_key_op(int key)
549 : {
550 1 : const struct sysrq_key_op *op_p = NULL;
551 1 : int i;
552 :
553 1 : i = sysrq_key_table_key2index(key);
554 1 : if (i != -1)
555 1 : op_p = sysrq_key_table[i];
556 :
557 1 : return op_p;
558 : }
559 :
560 1 : static void __sysrq_put_key_op(int key, const struct sysrq_key_op *op_p)
561 : {
562 1 : int i = sysrq_key_table_key2index(key);
563 :
564 1 : if (i != -1)
565 1 : sysrq_key_table[i] = op_p;
566 1 : }
567 :
568 0 : void __handle_sysrq(int key, bool check_mask)
569 : {
570 0 : const struct sysrq_key_op *op_p;
571 0 : int orig_log_level;
572 0 : int orig_suppress_printk;
573 0 : int i;
574 :
575 0 : orig_suppress_printk = suppress_printk;
576 0 : suppress_printk = 0;
577 :
578 0 : rcu_sysrq_start();
579 0 : rcu_read_lock();
580 : /*
581 : * Raise the apparent loglevel to maximum so that the sysrq header
582 : * is shown to provide the user with positive feedback. We do not
583 : * simply emit this at KERN_EMERG as that would change message
584 : * routing in the consumers of /proc/kmsg.
585 : */
586 0 : orig_log_level = console_loglevel;
587 0 : console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
588 :
589 0 : op_p = __sysrq_get_key_op(key);
590 0 : if (op_p) {
591 : /*
592 : * Should we check for enabled operations (/proc/sysrq-trigger
593 : * should not) and is the invoked operation enabled?
594 : */
595 0 : if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
596 0 : pr_info("%s\n", op_p->action_msg);
597 0 : console_loglevel = orig_log_level;
598 0 : op_p->handler(key);
599 : } else {
600 0 : pr_info("This sysrq operation is disabled.\n");
601 0 : console_loglevel = orig_log_level;
602 : }
603 : } else {
604 0 : pr_info("HELP : ");
605 : /* Only print the help msg once per handler */
606 0 : for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
607 0 : if (sysrq_key_table[i]) {
608 : int j;
609 :
610 0 : for (j = 0; sysrq_key_table[i] !=
611 0 : sysrq_key_table[j]; j++)
612 0 : ;
613 0 : if (j != i)
614 0 : continue;
615 0 : pr_cont("%s ", sysrq_key_table[i]->help_msg);
616 : }
617 : }
618 0 : pr_cont("\n");
619 0 : console_loglevel = orig_log_level;
620 : }
621 0 : rcu_read_unlock();
622 0 : rcu_sysrq_end();
623 :
624 0 : suppress_printk = orig_suppress_printk;
625 0 : }
626 :
627 0 : void handle_sysrq(int key)
628 : {
629 0 : if (sysrq_on())
630 0 : __handle_sysrq(key, true);
631 0 : }
632 : EXPORT_SYMBOL(handle_sysrq);
633 :
634 : #ifdef CONFIG_INPUT
635 : static int sysrq_reset_downtime_ms;
636 :
637 : /* Simple translation table for the SysRq keys */
638 : static const unsigned char sysrq_xlate[KEY_CNT] =
639 : "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */
640 : "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */
641 : "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */
642 : "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */
643 : "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */
644 : "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
645 : "\r\000/"; /* 0x60 - 0x6f */
646 :
647 : struct sysrq_state {
648 : struct input_handle handle;
649 : struct work_struct reinject_work;
650 : unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
651 : unsigned int alt;
652 : unsigned int alt_use;
653 : unsigned int shift;
654 : unsigned int shift_use;
655 : bool active;
656 : bool need_reinject;
657 : bool reinjecting;
658 :
659 : /* reset sequence handling */
660 : bool reset_canceled;
661 : bool reset_requested;
662 : unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)];
663 : int reset_seq_len;
664 : int reset_seq_cnt;
665 : int reset_seq_version;
666 : struct timer_list keyreset_timer;
667 : };
668 :
669 : #define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */
670 : static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX];
671 : static unsigned int sysrq_reset_seq_len;
672 : static unsigned int sysrq_reset_seq_version = 1;
673 :
674 0 : static void sysrq_parse_reset_sequence(struct sysrq_state *state)
675 : {
676 0 : int i;
677 0 : unsigned short key;
678 :
679 0 : state->reset_seq_cnt = 0;
680 :
681 0 : for (i = 0; i < sysrq_reset_seq_len; i++) {
682 0 : key = sysrq_reset_seq[i];
683 :
684 0 : if (key == KEY_RESERVED || key > KEY_MAX)
685 : break;
686 :
687 0 : __set_bit(key, state->reset_keybit);
688 0 : state->reset_seq_len++;
689 :
690 0 : if (test_bit(key, state->key_down))
691 0 : state->reset_seq_cnt++;
692 : }
693 :
694 : /* Disable reset until old keys are not released */
695 0 : state->reset_canceled = state->reset_seq_cnt != 0;
696 :
697 0 : state->reset_seq_version = sysrq_reset_seq_version;
698 0 : }
699 :
700 0 : static void sysrq_do_reset(struct timer_list *t)
701 : {
702 0 : struct sysrq_state *state = from_timer(state, t, keyreset_timer);
703 :
704 0 : state->reset_requested = true;
705 :
706 0 : orderly_reboot();
707 0 : }
708 :
709 0 : static void sysrq_handle_reset_request(struct sysrq_state *state)
710 : {
711 0 : if (state->reset_requested)
712 0 : __handle_sysrq(sysrq_xlate[KEY_B], false);
713 :
714 0 : if (sysrq_reset_downtime_ms)
715 0 : mod_timer(&state->keyreset_timer,
716 0 : jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms));
717 : else
718 0 : sysrq_do_reset(&state->keyreset_timer);
719 0 : }
720 :
721 0 : static void sysrq_detect_reset_sequence(struct sysrq_state *state,
722 : unsigned int code, int value)
723 : {
724 0 : if (!test_bit(code, state->reset_keybit)) {
725 : /*
726 : * Pressing any key _not_ in reset sequence cancels
727 : * the reset sequence. Also cancelling the timer in
728 : * case additional keys were pressed after a reset
729 : * has been requested.
730 : */
731 0 : if (value && state->reset_seq_cnt) {
732 0 : state->reset_canceled = true;
733 0 : del_timer(&state->keyreset_timer);
734 : }
735 0 : } else if (value == 0) {
736 : /*
737 : * Key release - all keys in the reset sequence need
738 : * to be pressed and held for the reset timeout
739 : * to hold.
740 : */
741 0 : del_timer(&state->keyreset_timer);
742 :
743 0 : if (--state->reset_seq_cnt == 0)
744 0 : state->reset_canceled = false;
745 0 : } else if (value == 1) {
746 : /* key press, not autorepeat */
747 0 : if (++state->reset_seq_cnt == state->reset_seq_len &&
748 0 : !state->reset_canceled) {
749 0 : sysrq_handle_reset_request(state);
750 : }
751 : }
752 0 : }
753 :
754 : #ifdef CONFIG_OF
755 : static void sysrq_of_get_keyreset_config(void)
756 : {
757 : u32 key;
758 : struct device_node *np;
759 : struct property *prop;
760 : const __be32 *p;
761 :
762 : np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq");
763 : if (!np) {
764 : pr_debug("No sysrq node found");
765 : return;
766 : }
767 :
768 : /* Reset in case a __weak definition was present */
769 : sysrq_reset_seq_len = 0;
770 :
771 : of_property_for_each_u32(np, "keyset", prop, p, key) {
772 : if (key == KEY_RESERVED || key > KEY_MAX ||
773 : sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX)
774 : break;
775 :
776 : sysrq_reset_seq[sysrq_reset_seq_len++] = (unsigned short)key;
777 : }
778 :
779 : /* Get reset timeout if any. */
780 : of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms);
781 :
782 : of_node_put(np);
783 : }
784 : #else
785 1 : static void sysrq_of_get_keyreset_config(void)
786 : {
787 1 : }
788 : #endif
789 :
790 0 : static void sysrq_reinject_alt_sysrq(struct work_struct *work)
791 : {
792 0 : struct sysrq_state *sysrq =
793 0 : container_of(work, struct sysrq_state, reinject_work);
794 0 : struct input_handle *handle = &sysrq->handle;
795 0 : unsigned int alt_code = sysrq->alt_use;
796 :
797 0 : if (sysrq->need_reinject) {
798 : /* we do not want the assignment to be reordered */
799 0 : sysrq->reinjecting = true;
800 0 : mb();
801 :
802 : /* Simulate press and release of Alt + SysRq */
803 0 : input_inject_event(handle, EV_KEY, alt_code, 1);
804 0 : input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
805 0 : input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
806 :
807 0 : input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
808 0 : input_inject_event(handle, EV_KEY, alt_code, 0);
809 0 : input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
810 :
811 0 : mb();
812 0 : sysrq->reinjecting = false;
813 : }
814 0 : }
815 :
816 0 : static bool sysrq_handle_keypress(struct sysrq_state *sysrq,
817 : unsigned int code, int value)
818 : {
819 0 : bool was_active = sysrq->active;
820 0 : bool suppress;
821 :
822 0 : switch (code) {
823 :
824 0 : case KEY_LEFTALT:
825 : case KEY_RIGHTALT:
826 0 : if (!value) {
827 : /* One of ALTs is being released */
828 0 : if (sysrq->active && code == sysrq->alt_use)
829 0 : sysrq->active = false;
830 :
831 0 : sysrq->alt = KEY_RESERVED;
832 :
833 0 : } else if (value != 2) {
834 0 : sysrq->alt = code;
835 0 : sysrq->need_reinject = false;
836 : }
837 : break;
838 :
839 0 : case KEY_LEFTSHIFT:
840 : case KEY_RIGHTSHIFT:
841 0 : if (!value)
842 0 : sysrq->shift = KEY_RESERVED;
843 0 : else if (value != 2)
844 0 : sysrq->shift = code;
845 : break;
846 :
847 0 : case KEY_SYSRQ:
848 0 : if (value == 1 && sysrq->alt != KEY_RESERVED) {
849 0 : sysrq->active = true;
850 0 : sysrq->alt_use = sysrq->alt;
851 : /* either RESERVED (for released) or actual code */
852 0 : sysrq->shift_use = sysrq->shift;
853 : /*
854 : * If nothing else will be pressed we'll need
855 : * to re-inject Alt-SysRq keysroke.
856 : */
857 0 : sysrq->need_reinject = true;
858 : }
859 :
860 : /*
861 : * Pretend that sysrq was never pressed at all. This
862 : * is needed to properly handle KGDB which will try
863 : * to release all keys after exiting debugger. If we
864 : * do not clear key bit it KGDB will end up sending
865 : * release events for Alt and SysRq, potentially
866 : * triggering print screen function.
867 : */
868 0 : if (sysrq->active)
869 0 : clear_bit(KEY_SYSRQ, sysrq->handle.dev->key);
870 :
871 : break;
872 :
873 0 : default:
874 0 : if (sysrq->active && value && value != 2) {
875 0 : unsigned char c = sysrq_xlate[code];
876 :
877 0 : sysrq->need_reinject = false;
878 0 : if (sysrq->shift_use != KEY_RESERVED)
879 0 : c = toupper(c);
880 0 : __handle_sysrq(c, true);
881 : }
882 : break;
883 : }
884 :
885 0 : suppress = sysrq->active;
886 :
887 0 : if (!sysrq->active) {
888 :
889 : /*
890 : * See if reset sequence has changed since the last time.
891 : */
892 0 : if (sysrq->reset_seq_version != sysrq_reset_seq_version)
893 0 : sysrq_parse_reset_sequence(sysrq);
894 :
895 : /*
896 : * If we are not suppressing key presses keep track of
897 : * keyboard state so we can release keys that have been
898 : * pressed before entering SysRq mode.
899 : */
900 0 : if (value)
901 0 : set_bit(code, sysrq->key_down);
902 : else
903 0 : clear_bit(code, sysrq->key_down);
904 :
905 0 : if (was_active)
906 0 : schedule_work(&sysrq->reinject_work);
907 :
908 : /* Check for reset sequence */
909 0 : sysrq_detect_reset_sequence(sysrq, code, value);
910 :
911 0 : } else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) {
912 : /*
913 : * Pass on release events for keys that was pressed before
914 : * entering SysRq mode.
915 : */
916 0 : suppress = false;
917 : }
918 :
919 0 : return suppress;
920 : }
921 :
922 0 : static bool sysrq_filter(struct input_handle *handle,
923 : unsigned int type, unsigned int code, int value)
924 : {
925 0 : struct sysrq_state *sysrq = handle->private;
926 0 : bool suppress;
927 :
928 : /*
929 : * Do not filter anything if we are in the process of re-injecting
930 : * Alt+SysRq combination.
931 : */
932 0 : if (sysrq->reinjecting)
933 : return false;
934 :
935 0 : switch (type) {
936 :
937 : case EV_SYN:
938 : suppress = false;
939 : break;
940 :
941 0 : case EV_KEY:
942 0 : suppress = sysrq_handle_keypress(sysrq, code, value);
943 0 : break;
944 :
945 0 : default:
946 0 : suppress = sysrq->active;
947 0 : break;
948 : }
949 :
950 : return suppress;
951 : }
952 :
953 0 : static int sysrq_connect(struct input_handler *handler,
954 : struct input_dev *dev,
955 : const struct input_device_id *id)
956 : {
957 0 : struct sysrq_state *sysrq;
958 0 : int error;
959 :
960 0 : sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);
961 0 : if (!sysrq)
962 : return -ENOMEM;
963 :
964 0 : INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);
965 :
966 0 : sysrq->handle.dev = dev;
967 0 : sysrq->handle.handler = handler;
968 0 : sysrq->handle.name = "sysrq";
969 0 : sysrq->handle.private = sysrq;
970 0 : timer_setup(&sysrq->keyreset_timer, sysrq_do_reset, 0);
971 :
972 0 : error = input_register_handle(&sysrq->handle);
973 0 : if (error) {
974 0 : pr_err("Failed to register input sysrq handler, error %d\n",
975 : error);
976 0 : goto err_free;
977 : }
978 :
979 0 : error = input_open_device(&sysrq->handle);
980 0 : if (error) {
981 0 : pr_err("Failed to open input device, error %d\n", error);
982 0 : goto err_unregister;
983 : }
984 :
985 : return 0;
986 :
987 0 : err_unregister:
988 0 : input_unregister_handle(&sysrq->handle);
989 0 : err_free:
990 0 : kfree(sysrq);
991 0 : return error;
992 : }
993 :
994 0 : static void sysrq_disconnect(struct input_handle *handle)
995 : {
996 0 : struct sysrq_state *sysrq = handle->private;
997 :
998 0 : input_close_device(handle);
999 0 : cancel_work_sync(&sysrq->reinject_work);
1000 0 : del_timer_sync(&sysrq->keyreset_timer);
1001 0 : input_unregister_handle(handle);
1002 0 : kfree(sysrq);
1003 0 : }
1004 :
1005 : /*
1006 : * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all
1007 : * keyboards have SysRq key predefined and so user may add it to keymap
1008 : * later, but we expect all such keyboards to have left alt.
1009 : */
1010 : static const struct input_device_id sysrq_ids[] = {
1011 : {
1012 : .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
1013 : INPUT_DEVICE_ID_MATCH_KEYBIT,
1014 : .evbit = { [BIT_WORD(EV_KEY)] = BIT_MASK(EV_KEY) },
1015 : .keybit = { [BIT_WORD(KEY_LEFTALT)] = BIT_MASK(KEY_LEFTALT) },
1016 : },
1017 : { },
1018 : };
1019 :
1020 : static struct input_handler sysrq_handler = {
1021 : .filter = sysrq_filter,
1022 : .connect = sysrq_connect,
1023 : .disconnect = sysrq_disconnect,
1024 : .name = "sysrq",
1025 : .id_table = sysrq_ids,
1026 : };
1027 :
1028 1 : static inline void sysrq_register_handler(void)
1029 : {
1030 1 : int error;
1031 :
1032 1 : sysrq_of_get_keyreset_config();
1033 :
1034 1 : error = input_register_handler(&sysrq_handler);
1035 1 : if (error)
1036 0 : pr_err("Failed to register input handler, error %d", error);
1037 1 : }
1038 :
1039 0 : static inline void sysrq_unregister_handler(void)
1040 : {
1041 0 : input_unregister_handler(&sysrq_handler);
1042 0 : }
1043 :
1044 0 : static int sysrq_reset_seq_param_set(const char *buffer,
1045 : const struct kernel_param *kp)
1046 : {
1047 0 : unsigned long val;
1048 0 : int error;
1049 :
1050 0 : error = kstrtoul(buffer, 0, &val);
1051 0 : if (error < 0)
1052 : return error;
1053 :
1054 0 : if (val > KEY_MAX)
1055 : return -EINVAL;
1056 :
1057 0 : *((unsigned short *)kp->arg) = val;
1058 0 : sysrq_reset_seq_version++;
1059 :
1060 0 : return 0;
1061 : }
1062 :
1063 : static const struct kernel_param_ops param_ops_sysrq_reset_seq = {
1064 : .get = param_get_ushort,
1065 : .set = sysrq_reset_seq_param_set,
1066 : };
1067 :
1068 : #define param_check_sysrq_reset_seq(name, p) \
1069 : __param_check(name, p, unsigned short)
1070 :
1071 : /*
1072 : * not really modular, but the easiest way to keep compat with existing
1073 : * bootargs behaviour is to continue using module_param here.
1074 : */
1075 : module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq,
1076 : &sysrq_reset_seq_len, 0644);
1077 :
1078 : module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644);
1079 :
1080 : #else
1081 :
1082 : static inline void sysrq_register_handler(void)
1083 : {
1084 : }
1085 :
1086 : static inline void sysrq_unregister_handler(void)
1087 : {
1088 : }
1089 :
1090 : #endif /* CONFIG_INPUT */
1091 :
1092 0 : int sysrq_toggle_support(int enable_mask)
1093 : {
1094 0 : bool was_enabled = sysrq_on();
1095 :
1096 0 : sysrq_enabled = enable_mask;
1097 :
1098 0 : if (was_enabled != sysrq_on()) {
1099 0 : if (sysrq_on())
1100 0 : sysrq_register_handler();
1101 : else
1102 0 : sysrq_unregister_handler();
1103 : }
1104 :
1105 0 : return 0;
1106 : }
1107 : EXPORT_SYMBOL_GPL(sysrq_toggle_support);
1108 :
1109 1 : static int __sysrq_swap_key_ops(int key, const struct sysrq_key_op *insert_op_p,
1110 : const struct sysrq_key_op *remove_op_p)
1111 : {
1112 1 : int retval;
1113 :
1114 1 : spin_lock(&sysrq_key_table_lock);
1115 1 : if (__sysrq_get_key_op(key) == remove_op_p) {
1116 1 : __sysrq_put_key_op(key, insert_op_p);
1117 1 : retval = 0;
1118 : } else {
1119 : retval = -1;
1120 : }
1121 1 : spin_unlock(&sysrq_key_table_lock);
1122 :
1123 : /*
1124 : * A concurrent __handle_sysrq either got the old op or the new op.
1125 : * Wait for it to go away before returning, so the code for an old
1126 : * op is not freed (eg. on module unload) while it is in use.
1127 : */
1128 1 : synchronize_rcu();
1129 :
1130 1 : return retval;
1131 : }
1132 :
1133 1 : int register_sysrq_key(int key, const struct sysrq_key_op *op_p)
1134 : {
1135 1 : return __sysrq_swap_key_ops(key, op_p, NULL);
1136 : }
1137 : EXPORT_SYMBOL(register_sysrq_key);
1138 :
1139 0 : int unregister_sysrq_key(int key, const struct sysrq_key_op *op_p)
1140 : {
1141 0 : return __sysrq_swap_key_ops(key, NULL, op_p);
1142 : }
1143 : EXPORT_SYMBOL(unregister_sysrq_key);
1144 :
1145 : #ifdef CONFIG_PROC_FS
1146 : /*
1147 : * writing 'C' to /proc/sysrq-trigger is like sysrq-C
1148 : */
1149 0 : static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
1150 : size_t count, loff_t *ppos)
1151 : {
1152 0 : if (count) {
1153 0 : char c;
1154 :
1155 0 : if (get_user(c, buf))
1156 : return -EFAULT;
1157 0 : __handle_sysrq(c, false);
1158 : }
1159 :
1160 0 : return count;
1161 : }
1162 :
1163 : static const struct proc_ops sysrq_trigger_proc_ops = {
1164 : .proc_write = write_sysrq_trigger,
1165 : .proc_lseek = noop_llseek,
1166 : };
1167 :
1168 1 : static void sysrq_init_procfs(void)
1169 : {
1170 1 : if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
1171 : &sysrq_trigger_proc_ops))
1172 0 : pr_err("Failed to register proc interface\n");
1173 1 : }
1174 :
1175 : #else
1176 :
1177 : static inline void sysrq_init_procfs(void)
1178 : {
1179 : }
1180 :
1181 : #endif /* CONFIG_PROC_FS */
1182 :
1183 1 : static int __init sysrq_init(void)
1184 : {
1185 1 : sysrq_init_procfs();
1186 :
1187 1 : if (sysrq_on())
1188 1 : sysrq_register_handler();
1189 :
1190 1 : return 0;
1191 : }
1192 : device_initcall(sysrq_init);
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