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 | static bool sysrq_on(void) |
63 | { |
64 | 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 | int sysrq_mask(void) |
73 | { |
74 | if (sysrq_always_enabled) |
75 | return 1; |
76 | 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 | static bool sysrq_on_mask(int mask) |
84 | { |
85 | return sysrq_always_enabled || |
86 | sysrq_enabled == 1 || |
87 | (sysrq_enabled & mask); |
88 | } |
89 | |
90 | static int __init sysrq_always_enabled_setup(char *str) |
91 | { |
92 | sysrq_always_enabled = true; |
93 | pr_info("sysrq always enabled.\n" ); |
94 | |
95 | return 1; |
96 | } |
97 | |
98 | __setup("sysrq_always_enabled" , sysrq_always_enabled_setup); |
99 | |
100 | |
101 | static void sysrq_handle_loglevel(u8 key) |
102 | { |
103 | u8 loglevel = key - '0'; |
104 | |
105 | console_loglevel = CONSOLE_LOGLEVEL_DEFAULT; |
106 | pr_info("Loglevel set to %u\n" , loglevel); |
107 | console_loglevel = loglevel; |
108 | } |
109 | static const struct sysrq_key_op sysrq_loglevel_op = { |
110 | .handler = sysrq_handle_loglevel, |
111 | .help_msg = "loglevel(0-9)" , |
112 | .action_msg = "Changing Loglevel" , |
113 | .enable_mask = SYSRQ_ENABLE_LOG, |
114 | }; |
115 | |
116 | #ifdef CONFIG_VT |
117 | static void sysrq_handle_SAK(u8 key) |
118 | { |
119 | struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work; |
120 | |
121 | schedule_work(work: SAK_work); |
122 | } |
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 | static void sysrq_handle_unraw(u8 key) |
135 | { |
136 | vt_reset_unicode(console: fg_console); |
137 | } |
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 | static void sysrq_handle_crash(u8 key) |
150 | { |
151 | /* release the RCU read lock before crashing */ |
152 | rcu_read_unlock(); |
153 | |
154 | panic(fmt: "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 | static void sysrq_handle_reboot(u8 key) |
164 | { |
165 | lockdep_off(); |
166 | local_irq_enable(); |
167 | emergency_restart(); |
168 | } |
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 | static void sysrq_handle_sync(u8 key) |
179 | { |
180 | emergency_sync(); |
181 | } |
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 | static void sysrq_handle_show_timers(u8 key) |
190 | { |
191 | sysrq_timer_list_show(); |
192 | } |
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 | static void sysrq_handle_mountro(u8 key) |
201 | { |
202 | emergency_remount(); |
203 | } |
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 | static void sysrq_handle_showlocks(u8 key) |
213 | { |
214 | debug_show_all_locks(); |
215 | } |
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 | pr_info("CPU%d: backtrace skipped as idling\n" , smp_processor_id()); |
236 | return; |
237 | } |
238 | |
239 | raw_spin_lock_irqsave(&show_lock, flags); |
240 | pr_info("CPU%d:\n" , smp_processor_id()); |
241 | show_stack(NULL, NULL, KERN_INFO); |
242 | raw_spin_unlock_irqrestore(&show_lock, flags); |
243 | } |
244 | |
245 | static void sysrq_showregs_othercpus(struct work_struct *dummy) |
246 | { |
247 | smp_call_function(func: showacpu, NULL, wait: 0); |
248 | } |
249 | |
250 | static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus); |
251 | |
252 | static void sysrq_handle_showallcpus(u8 key) |
253 | { |
254 | /* |
255 | * Fall back to the workqueue based printing if the |
256 | * backtrace printing did not succeed or the |
257 | * architecture has no support for it: |
258 | */ |
259 | if (!trigger_all_cpu_backtrace()) { |
260 | struct pt_regs *regs = NULL; |
261 | |
262 | if (in_hardirq()) |
263 | regs = get_irq_regs(); |
264 | |
265 | pr_info("CPU%d:\n" , get_cpu()); |
266 | if (regs) |
267 | show_regs(regs); |
268 | else |
269 | show_stack(NULL, NULL, KERN_INFO); |
270 | |
271 | schedule_work(work: &sysrq_showallcpus); |
272 | put_cpu(); |
273 | } |
274 | } |
275 | |
276 | static const struct sysrq_key_op sysrq_showallcpus_op = { |
277 | .handler = sysrq_handle_showallcpus, |
278 | .help_msg = "show-backtrace-all-active-cpus(l)" , |
279 | .action_msg = "Show backtrace of all active CPUs" , |
280 | .enable_mask = SYSRQ_ENABLE_DUMP, |
281 | }; |
282 | #else |
283 | #define sysrq_showallcpus_op (*(const struct sysrq_key_op *)NULL) |
284 | #endif |
285 | |
286 | static void sysrq_handle_showregs(u8 key) |
287 | { |
288 | struct pt_regs *regs = NULL; |
289 | |
290 | if (in_hardirq()) |
291 | regs = get_irq_regs(); |
292 | if (regs) |
293 | show_regs(regs); |
294 | perf_event_print_debug(); |
295 | } |
296 | static const struct sysrq_key_op sysrq_showregs_op = { |
297 | .handler = sysrq_handle_showregs, |
298 | .help_msg = "show-registers(p)" , |
299 | .action_msg = "Show Regs" , |
300 | .enable_mask = SYSRQ_ENABLE_DUMP, |
301 | }; |
302 | |
303 | static void sysrq_handle_showstate(u8 key) |
304 | { |
305 | show_state(); |
306 | show_all_workqueues(); |
307 | } |
308 | static const struct sysrq_key_op sysrq_showstate_op = { |
309 | .handler = sysrq_handle_showstate, |
310 | .help_msg = "show-task-states(t)" , |
311 | .action_msg = "Show State" , |
312 | .enable_mask = SYSRQ_ENABLE_DUMP, |
313 | }; |
314 | |
315 | static void sysrq_handle_showstate_blocked(u8 key) |
316 | { |
317 | show_state_filter(TASK_UNINTERRUPTIBLE); |
318 | } |
319 | static const struct sysrq_key_op sysrq_showstate_blocked_op = { |
320 | .handler = sysrq_handle_showstate_blocked, |
321 | .help_msg = "show-blocked-tasks(w)" , |
322 | .action_msg = "Show Blocked State" , |
323 | .enable_mask = SYSRQ_ENABLE_DUMP, |
324 | }; |
325 | |
326 | #ifdef CONFIG_TRACING |
327 | #include <linux/ftrace.h> |
328 | |
329 | static void sysrq_ftrace_dump(u8 key) |
330 | { |
331 | ftrace_dump(oops_dump_mode: DUMP_ALL); |
332 | } |
333 | static const struct sysrq_key_op sysrq_ftrace_dump_op = { |
334 | .handler = sysrq_ftrace_dump, |
335 | .help_msg = "dump-ftrace-buffer(z)" , |
336 | .action_msg = "Dump ftrace buffer" , |
337 | .enable_mask = SYSRQ_ENABLE_DUMP, |
338 | }; |
339 | #else |
340 | #define sysrq_ftrace_dump_op (*(const struct sysrq_key_op *)NULL) |
341 | #endif |
342 | |
343 | static void sysrq_handle_showmem(u8 key) |
344 | { |
345 | show_mem(); |
346 | } |
347 | static const struct sysrq_key_op sysrq_showmem_op = { |
348 | .handler = sysrq_handle_showmem, |
349 | .help_msg = "show-memory-usage(m)" , |
350 | .action_msg = "Show Memory" , |
351 | .enable_mask = SYSRQ_ENABLE_DUMP, |
352 | }; |
353 | |
354 | /* |
355 | * Signal sysrq helper function. Sends a signal to all user processes. |
356 | */ |
357 | static void send_sig_all(int sig) |
358 | { |
359 | struct task_struct *p; |
360 | |
361 | read_lock(&tasklist_lock); |
362 | for_each_process(p) { |
363 | if (p->flags & PF_KTHREAD) |
364 | continue; |
365 | if (is_global_init(tsk: p)) |
366 | continue; |
367 | |
368 | do_send_sig_info(sig, SEND_SIG_PRIV, p, type: PIDTYPE_MAX); |
369 | } |
370 | read_unlock(&tasklist_lock); |
371 | } |
372 | |
373 | static void sysrq_handle_term(u8 key) |
374 | { |
375 | send_sig_all(SIGTERM); |
376 | console_loglevel = CONSOLE_LOGLEVEL_DEBUG; |
377 | } |
378 | static const struct sysrq_key_op sysrq_term_op = { |
379 | .handler = sysrq_handle_term, |
380 | .help_msg = "terminate-all-tasks(e)" , |
381 | .action_msg = "Terminate All Tasks" , |
382 | .enable_mask = SYSRQ_ENABLE_SIGNAL, |
383 | }; |
384 | |
385 | static void moom_callback(struct work_struct *ignored) |
386 | { |
387 | const gfp_t gfp_mask = GFP_KERNEL; |
388 | struct oom_control oc = { |
389 | .zonelist = node_zonelist(first_memory_node, flags: gfp_mask), |
390 | .nodemask = NULL, |
391 | .memcg = NULL, |
392 | .gfp_mask = gfp_mask, |
393 | .order = -1, |
394 | }; |
395 | |
396 | mutex_lock(&oom_lock); |
397 | if (!out_of_memory(oc: &oc)) |
398 | pr_info("OOM request ignored. No task eligible\n" ); |
399 | mutex_unlock(lock: &oom_lock); |
400 | } |
401 | |
402 | static DECLARE_WORK(moom_work, moom_callback); |
403 | |
404 | static void sysrq_handle_moom(u8 key) |
405 | { |
406 | schedule_work(work: &moom_work); |
407 | } |
408 | static const struct sysrq_key_op sysrq_moom_op = { |
409 | .handler = sysrq_handle_moom, |
410 | .help_msg = "memory-full-oom-kill(f)" , |
411 | .action_msg = "Manual OOM execution" , |
412 | .enable_mask = SYSRQ_ENABLE_SIGNAL, |
413 | }; |
414 | |
415 | #ifdef CONFIG_BLOCK |
416 | static void sysrq_handle_thaw(u8 key) |
417 | { |
418 | emergency_thaw_all(); |
419 | } |
420 | static const struct sysrq_key_op sysrq_thaw_op = { |
421 | .handler = sysrq_handle_thaw, |
422 | .help_msg = "thaw-filesystems(j)" , |
423 | .action_msg = "Emergency Thaw of all frozen filesystems" , |
424 | .enable_mask = SYSRQ_ENABLE_SIGNAL, |
425 | }; |
426 | #else |
427 | #define sysrq_thaw_op (*(const struct sysrq_key_op *)NULL) |
428 | #endif |
429 | |
430 | static void sysrq_handle_kill(u8 key) |
431 | { |
432 | send_sig_all(SIGKILL); |
433 | console_loglevel = CONSOLE_LOGLEVEL_DEBUG; |
434 | } |
435 | static const struct sysrq_key_op sysrq_kill_op = { |
436 | .handler = sysrq_handle_kill, |
437 | .help_msg = "kill-all-tasks(i)" , |
438 | .action_msg = "Kill All Tasks" , |
439 | .enable_mask = SYSRQ_ENABLE_SIGNAL, |
440 | }; |
441 | |
442 | static void sysrq_handle_unrt(u8 key) |
443 | { |
444 | normalize_rt_tasks(); |
445 | } |
446 | static const struct sysrq_key_op sysrq_unrt_op = { |
447 | .handler = sysrq_handle_unrt, |
448 | .help_msg = "nice-all-RT-tasks(n)" , |
449 | .action_msg = "Nice All RT Tasks" , |
450 | .enable_mask = SYSRQ_ENABLE_RTNICE, |
451 | }; |
452 | |
453 | /* Key Operations table and lock */ |
454 | static DEFINE_SPINLOCK(sysrq_key_table_lock); |
455 | |
456 | static const struct sysrq_key_op *sysrq_key_table[62] = { |
457 | &sysrq_loglevel_op, /* 0 */ |
458 | &sysrq_loglevel_op, /* 1 */ |
459 | &sysrq_loglevel_op, /* 2 */ |
460 | &sysrq_loglevel_op, /* 3 */ |
461 | &sysrq_loglevel_op, /* 4 */ |
462 | &sysrq_loglevel_op, /* 5 */ |
463 | &sysrq_loglevel_op, /* 6 */ |
464 | &sysrq_loglevel_op, /* 7 */ |
465 | &sysrq_loglevel_op, /* 8 */ |
466 | &sysrq_loglevel_op, /* 9 */ |
467 | |
468 | /* |
469 | * a: Don't use for system provided sysrqs, it is handled specially on |
470 | * sparc and will never arrive. |
471 | */ |
472 | NULL, /* a */ |
473 | &sysrq_reboot_op, /* b */ |
474 | &sysrq_crash_op, /* c */ |
475 | &sysrq_showlocks_op, /* d */ |
476 | &sysrq_term_op, /* e */ |
477 | &sysrq_moom_op, /* f */ |
478 | /* g: May be registered for the kernel debugger */ |
479 | NULL, /* g */ |
480 | NULL, /* h - reserved for help */ |
481 | &sysrq_kill_op, /* i */ |
482 | &sysrq_thaw_op, /* j */ |
483 | &sysrq_SAK_op, /* k */ |
484 | &sysrq_showallcpus_op, /* l */ |
485 | &sysrq_showmem_op, /* m */ |
486 | &sysrq_unrt_op, /* n */ |
487 | /* o: This will often be registered as 'Off' at init time */ |
488 | NULL, /* o */ |
489 | &sysrq_showregs_op, /* p */ |
490 | &sysrq_show_timers_op, /* q */ |
491 | &sysrq_unraw_op, /* r */ |
492 | &sysrq_sync_op, /* s */ |
493 | &sysrq_showstate_op, /* t */ |
494 | &sysrq_mountro_op, /* u */ |
495 | /* v: May be registered for frame buffer console restore */ |
496 | NULL, /* v */ |
497 | &sysrq_showstate_blocked_op, /* w */ |
498 | /* x: May be registered on mips for TLB dump */ |
499 | /* x: May be registered on ppc/powerpc for xmon */ |
500 | /* x: May be registered on sparc64 for global PMU dump */ |
501 | NULL, /* x */ |
502 | /* y: May be registered on sparc64 for global register dump */ |
503 | NULL, /* y */ |
504 | &sysrq_ftrace_dump_op, /* z */ |
505 | NULL, /* A */ |
506 | NULL, /* B */ |
507 | NULL, /* C */ |
508 | NULL, /* D */ |
509 | NULL, /* E */ |
510 | NULL, /* F */ |
511 | NULL, /* G */ |
512 | NULL, /* H */ |
513 | NULL, /* I */ |
514 | NULL, /* J */ |
515 | NULL, /* K */ |
516 | NULL, /* L */ |
517 | NULL, /* M */ |
518 | NULL, /* N */ |
519 | NULL, /* O */ |
520 | NULL, /* P */ |
521 | NULL, /* Q */ |
522 | NULL, /* R */ |
523 | NULL, /* S */ |
524 | NULL, /* T */ |
525 | NULL, /* U */ |
526 | NULL, /* V */ |
527 | NULL, /* W */ |
528 | NULL, /* X */ |
529 | NULL, /* Y */ |
530 | NULL, /* Z */ |
531 | }; |
532 | |
533 | /* key2index calculation, -1 on invalid index */ |
534 | static int sysrq_key_table_key2index(u8 key) |
535 | { |
536 | switch (key) { |
537 | case '0' ... '9': |
538 | return key - '0'; |
539 | case 'a' ... 'z': |
540 | return key - 'a' + 10; |
541 | case 'A' ... 'Z': |
542 | return key - 'A' + 10 + 26; |
543 | default: |
544 | return -1; |
545 | } |
546 | } |
547 | |
548 | /* |
549 | * get and put functions for the table, exposed to modules. |
550 | */ |
551 | static const struct sysrq_key_op *__sysrq_get_key_op(u8 key) |
552 | { |
553 | const struct sysrq_key_op *op_p = NULL; |
554 | int i; |
555 | |
556 | i = sysrq_key_table_key2index(key); |
557 | if (i != -1) |
558 | op_p = sysrq_key_table[i]; |
559 | |
560 | return op_p; |
561 | } |
562 | |
563 | static void __sysrq_put_key_op(u8 key, const struct sysrq_key_op *op_p) |
564 | { |
565 | int i = sysrq_key_table_key2index(key); |
566 | |
567 | if (i != -1) |
568 | sysrq_key_table[i] = op_p; |
569 | } |
570 | |
571 | void __handle_sysrq(u8 key, bool check_mask) |
572 | { |
573 | const struct sysrq_key_op *op_p; |
574 | int orig_log_level; |
575 | int orig_suppress_printk; |
576 | int i; |
577 | |
578 | orig_suppress_printk = suppress_printk; |
579 | suppress_printk = 0; |
580 | |
581 | rcu_sysrq_start(); |
582 | rcu_read_lock(); |
583 | /* |
584 | * Raise the apparent loglevel to maximum so that the sysrq header |
585 | * is shown to provide the user with positive feedback. We do not |
586 | * simply emit this at KERN_EMERG as that would change message |
587 | * routing in the consumers of /proc/kmsg. |
588 | */ |
589 | orig_log_level = console_loglevel; |
590 | console_loglevel = CONSOLE_LOGLEVEL_DEFAULT; |
591 | |
592 | op_p = __sysrq_get_key_op(key); |
593 | if (op_p) { |
594 | /* |
595 | * Should we check for enabled operations (/proc/sysrq-trigger |
596 | * should not) and is the invoked operation enabled? |
597 | */ |
598 | if (!check_mask || sysrq_on_mask(mask: op_p->enable_mask)) { |
599 | pr_info("%s\n" , op_p->action_msg); |
600 | console_loglevel = orig_log_level; |
601 | op_p->handler(key); |
602 | } else { |
603 | pr_info("This sysrq operation is disabled.\n" ); |
604 | console_loglevel = orig_log_level; |
605 | } |
606 | } else { |
607 | pr_info("HELP : " ); |
608 | /* Only print the help msg once per handler */ |
609 | for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) { |
610 | if (sysrq_key_table[i]) { |
611 | int j; |
612 | |
613 | for (j = 0; sysrq_key_table[i] != |
614 | sysrq_key_table[j]; j++) |
615 | ; |
616 | if (j != i) |
617 | continue; |
618 | pr_cont("%s " , sysrq_key_table[i]->help_msg); |
619 | } |
620 | } |
621 | pr_cont("\n" ); |
622 | console_loglevel = orig_log_level; |
623 | } |
624 | rcu_read_unlock(); |
625 | rcu_sysrq_end(); |
626 | |
627 | suppress_printk = orig_suppress_printk; |
628 | } |
629 | |
630 | void handle_sysrq(u8 key) |
631 | { |
632 | if (sysrq_on()) |
633 | __handle_sysrq(key, check_mask: true); |
634 | } |
635 | EXPORT_SYMBOL(handle_sysrq); |
636 | |
637 | #ifdef CONFIG_INPUT |
638 | static int sysrq_reset_downtime_ms; |
639 | |
640 | /* Simple translation table for the SysRq keys */ |
641 | static const unsigned char sysrq_xlate[KEY_CNT] = |
642 | "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */ |
643 | "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */ |
644 | "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */ |
645 | "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */ |
646 | "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */ |
647 | "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */ |
648 | "\r\000/" ; /* 0x60 - 0x6f */ |
649 | |
650 | struct sysrq_state { |
651 | struct input_handle handle; |
652 | struct work_struct reinject_work; |
653 | unsigned long key_down[BITS_TO_LONGS(KEY_CNT)]; |
654 | unsigned int alt; |
655 | unsigned int alt_use; |
656 | unsigned int shift; |
657 | unsigned int shift_use; |
658 | bool active; |
659 | bool need_reinject; |
660 | bool reinjecting; |
661 | |
662 | /* reset sequence handling */ |
663 | bool reset_canceled; |
664 | bool reset_requested; |
665 | unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)]; |
666 | int reset_seq_len; |
667 | int reset_seq_cnt; |
668 | int reset_seq_version; |
669 | struct timer_list keyreset_timer; |
670 | }; |
671 | |
672 | #define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */ |
673 | static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX]; |
674 | static unsigned int sysrq_reset_seq_len; |
675 | static unsigned int sysrq_reset_seq_version = 1; |
676 | |
677 | static void sysrq_parse_reset_sequence(struct sysrq_state *state) |
678 | { |
679 | int i; |
680 | unsigned short key; |
681 | |
682 | state->reset_seq_cnt = 0; |
683 | |
684 | for (i = 0; i < sysrq_reset_seq_len; i++) { |
685 | key = sysrq_reset_seq[i]; |
686 | |
687 | if (key == KEY_RESERVED || key > KEY_MAX) |
688 | break; |
689 | |
690 | __set_bit(key, state->reset_keybit); |
691 | state->reset_seq_len++; |
692 | |
693 | if (test_bit(key, state->key_down)) |
694 | state->reset_seq_cnt++; |
695 | } |
696 | |
697 | /* Disable reset until old keys are not released */ |
698 | state->reset_canceled = state->reset_seq_cnt != 0; |
699 | |
700 | state->reset_seq_version = sysrq_reset_seq_version; |
701 | } |
702 | |
703 | static void sysrq_do_reset(struct timer_list *t) |
704 | { |
705 | struct sysrq_state *state = from_timer(state, t, keyreset_timer); |
706 | |
707 | state->reset_requested = true; |
708 | |
709 | orderly_reboot(); |
710 | } |
711 | |
712 | static void sysrq_handle_reset_request(struct sysrq_state *state) |
713 | { |
714 | if (state->reset_requested) |
715 | __handle_sysrq(key: sysrq_xlate[KEY_B], check_mask: false); |
716 | |
717 | if (sysrq_reset_downtime_ms) |
718 | mod_timer(timer: &state->keyreset_timer, |
719 | expires: jiffies + msecs_to_jiffies(m: sysrq_reset_downtime_ms)); |
720 | else |
721 | sysrq_do_reset(t: &state->keyreset_timer); |
722 | } |
723 | |
724 | static void sysrq_detect_reset_sequence(struct sysrq_state *state, |
725 | unsigned int code, int value) |
726 | { |
727 | if (!test_bit(code, state->reset_keybit)) { |
728 | /* |
729 | * Pressing any key _not_ in reset sequence cancels |
730 | * the reset sequence. Also cancelling the timer in |
731 | * case additional keys were pressed after a reset |
732 | * has been requested. |
733 | */ |
734 | if (value && state->reset_seq_cnt) { |
735 | state->reset_canceled = true; |
736 | del_timer(timer: &state->keyreset_timer); |
737 | } |
738 | } else if (value == 0) { |
739 | /* |
740 | * Key release - all keys in the reset sequence need |
741 | * to be pressed and held for the reset timeout |
742 | * to hold. |
743 | */ |
744 | del_timer(timer: &state->keyreset_timer); |
745 | |
746 | if (--state->reset_seq_cnt == 0) |
747 | state->reset_canceled = false; |
748 | } else if (value == 1) { |
749 | /* key press, not autorepeat */ |
750 | if (++state->reset_seq_cnt == state->reset_seq_len && |
751 | !state->reset_canceled) { |
752 | sysrq_handle_reset_request(state); |
753 | } |
754 | } |
755 | } |
756 | |
757 | #ifdef CONFIG_OF |
758 | static void sysrq_of_get_keyreset_config(void) |
759 | { |
760 | u32 key; |
761 | struct device_node *np; |
762 | struct property *prop; |
763 | const __be32 *p; |
764 | |
765 | np = of_find_node_by_path(path: "/chosen/linux,sysrq-reset-seq" ); |
766 | if (!np) { |
767 | pr_debug("No sysrq node found" ); |
768 | return; |
769 | } |
770 | |
771 | /* Reset in case a __weak definition was present */ |
772 | sysrq_reset_seq_len = 0; |
773 | |
774 | of_property_for_each_u32(np, "keyset" , prop, p, key) { |
775 | if (key == KEY_RESERVED || key > KEY_MAX || |
776 | sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX) |
777 | break; |
778 | |
779 | sysrq_reset_seq[sysrq_reset_seq_len++] = (unsigned short)key; |
780 | } |
781 | |
782 | /* Get reset timeout if any. */ |
783 | of_property_read_u32(np, propname: "timeout-ms" , out_value: &sysrq_reset_downtime_ms); |
784 | |
785 | of_node_put(node: np); |
786 | } |
787 | #else |
788 | static void sysrq_of_get_keyreset_config(void) |
789 | { |
790 | } |
791 | #endif |
792 | |
793 | static void sysrq_reinject_alt_sysrq(struct work_struct *work) |
794 | { |
795 | struct sysrq_state *sysrq = |
796 | container_of(work, struct sysrq_state, reinject_work); |
797 | struct input_handle *handle = &sysrq->handle; |
798 | unsigned int alt_code = sysrq->alt_use; |
799 | |
800 | if (sysrq->need_reinject) { |
801 | /* we do not want the assignment to be reordered */ |
802 | sysrq->reinjecting = true; |
803 | mb(); |
804 | |
805 | /* Simulate press and release of Alt + SysRq */ |
806 | input_inject_event(handle, EV_KEY, code: alt_code, value: 1); |
807 | input_inject_event(handle, EV_KEY, KEY_SYSRQ, value: 1); |
808 | input_inject_event(handle, EV_SYN, SYN_REPORT, value: 1); |
809 | |
810 | input_inject_event(handle, EV_KEY, KEY_SYSRQ, value: 0); |
811 | input_inject_event(handle, EV_KEY, code: alt_code, value: 0); |
812 | input_inject_event(handle, EV_SYN, SYN_REPORT, value: 1); |
813 | |
814 | mb(); |
815 | sysrq->reinjecting = false; |
816 | } |
817 | } |
818 | |
819 | static bool sysrq_handle_keypress(struct sysrq_state *sysrq, |
820 | unsigned int code, int value) |
821 | { |
822 | bool was_active = sysrq->active; |
823 | bool suppress; |
824 | |
825 | switch (code) { |
826 | |
827 | case KEY_LEFTALT: |
828 | case KEY_RIGHTALT: |
829 | if (!value) { |
830 | /* One of ALTs is being released */ |
831 | if (sysrq->active && code == sysrq->alt_use) |
832 | sysrq->active = false; |
833 | |
834 | sysrq->alt = KEY_RESERVED; |
835 | |
836 | } else if (value != 2) { |
837 | sysrq->alt = code; |
838 | sysrq->need_reinject = false; |
839 | } |
840 | break; |
841 | |
842 | case KEY_LEFTSHIFT: |
843 | case KEY_RIGHTSHIFT: |
844 | if (!value) |
845 | sysrq->shift = KEY_RESERVED; |
846 | else if (value != 2) |
847 | sysrq->shift = code; |
848 | if (sysrq->active) |
849 | sysrq->shift_use = sysrq->shift; |
850 | break; |
851 | |
852 | case KEY_SYSRQ: |
853 | if (value == 1 && sysrq->alt != KEY_RESERVED) { |
854 | sysrq->active = true; |
855 | sysrq->alt_use = sysrq->alt; |
856 | /* either RESERVED (for released) or actual code */ |
857 | sysrq->shift_use = sysrq->shift; |
858 | /* |
859 | * If nothing else will be pressed we'll need |
860 | * to re-inject Alt-SysRq keysroke. |
861 | */ |
862 | sysrq->need_reinject = true; |
863 | } |
864 | |
865 | /* |
866 | * Pretend that sysrq was never pressed at all. This |
867 | * is needed to properly handle KGDB which will try |
868 | * to release all keys after exiting debugger. If we |
869 | * do not clear key bit it KGDB will end up sending |
870 | * release events for Alt and SysRq, potentially |
871 | * triggering print screen function. |
872 | */ |
873 | if (sysrq->active) |
874 | clear_bit(KEY_SYSRQ, addr: sysrq->handle.dev->key); |
875 | |
876 | break; |
877 | |
878 | default: |
879 | if (sysrq->active && value && value != 2) { |
880 | unsigned char c = sysrq_xlate[code]; |
881 | |
882 | sysrq->need_reinject = false; |
883 | if (sysrq->shift_use != KEY_RESERVED) |
884 | c = toupper(c); |
885 | __handle_sysrq(key: c, check_mask: true); |
886 | } |
887 | break; |
888 | } |
889 | |
890 | suppress = sysrq->active; |
891 | |
892 | if (!sysrq->active) { |
893 | |
894 | /* |
895 | * See if reset sequence has changed since the last time. |
896 | */ |
897 | if (sysrq->reset_seq_version != sysrq_reset_seq_version) |
898 | sysrq_parse_reset_sequence(state: sysrq); |
899 | |
900 | /* |
901 | * If we are not suppressing key presses keep track of |
902 | * keyboard state so we can release keys that have been |
903 | * pressed before entering SysRq mode. |
904 | */ |
905 | if (value) |
906 | set_bit(nr: code, addr: sysrq->key_down); |
907 | else |
908 | clear_bit(nr: code, addr: sysrq->key_down); |
909 | |
910 | if (was_active) |
911 | schedule_work(work: &sysrq->reinject_work); |
912 | |
913 | /* Check for reset sequence */ |
914 | sysrq_detect_reset_sequence(state: sysrq, code, value); |
915 | |
916 | } else if (value == 0 && test_and_clear_bit(nr: code, addr: sysrq->key_down)) { |
917 | /* |
918 | * Pass on release events for keys that was pressed before |
919 | * entering SysRq mode. |
920 | */ |
921 | suppress = false; |
922 | } |
923 | |
924 | return suppress; |
925 | } |
926 | |
927 | static bool sysrq_filter(struct input_handle *handle, |
928 | unsigned int type, unsigned int code, int value) |
929 | { |
930 | struct sysrq_state *sysrq = handle->private; |
931 | bool suppress; |
932 | |
933 | /* |
934 | * Do not filter anything if we are in the process of re-injecting |
935 | * Alt+SysRq combination. |
936 | */ |
937 | if (sysrq->reinjecting) |
938 | return false; |
939 | |
940 | switch (type) { |
941 | |
942 | case EV_SYN: |
943 | suppress = false; |
944 | break; |
945 | |
946 | case EV_KEY: |
947 | suppress = sysrq_handle_keypress(sysrq, code, value); |
948 | break; |
949 | |
950 | default: |
951 | suppress = sysrq->active; |
952 | break; |
953 | } |
954 | |
955 | return suppress; |
956 | } |
957 | |
958 | static int sysrq_connect(struct input_handler *handler, |
959 | struct input_dev *dev, |
960 | const struct input_device_id *id) |
961 | { |
962 | struct sysrq_state *sysrq; |
963 | int error; |
964 | |
965 | sysrq = kzalloc(size: sizeof(struct sysrq_state), GFP_KERNEL); |
966 | if (!sysrq) |
967 | return -ENOMEM; |
968 | |
969 | INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq); |
970 | |
971 | sysrq->handle.dev = dev; |
972 | sysrq->handle.handler = handler; |
973 | sysrq->handle.name = "sysrq" ; |
974 | sysrq->handle.private = sysrq; |
975 | timer_setup(&sysrq->keyreset_timer, sysrq_do_reset, 0); |
976 | |
977 | error = input_register_handle(&sysrq->handle); |
978 | if (error) { |
979 | pr_err("Failed to register input sysrq handler, error %d\n" , |
980 | error); |
981 | goto err_free; |
982 | } |
983 | |
984 | error = input_open_device(&sysrq->handle); |
985 | if (error) { |
986 | pr_err("Failed to open input device, error %d\n" , error); |
987 | goto err_unregister; |
988 | } |
989 | |
990 | return 0; |
991 | |
992 | err_unregister: |
993 | input_unregister_handle(&sysrq->handle); |
994 | err_free: |
995 | kfree(objp: sysrq); |
996 | return error; |
997 | } |
998 | |
999 | static void sysrq_disconnect(struct input_handle *handle) |
1000 | { |
1001 | struct sysrq_state *sysrq = handle->private; |
1002 | |
1003 | input_close_device(handle); |
1004 | cancel_work_sync(work: &sysrq->reinject_work); |
1005 | timer_shutdown_sync(timer: &sysrq->keyreset_timer); |
1006 | input_unregister_handle(handle); |
1007 | kfree(objp: sysrq); |
1008 | } |
1009 | |
1010 | /* |
1011 | * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all |
1012 | * keyboards have SysRq key predefined and so user may add it to keymap |
1013 | * later, but we expect all such keyboards to have left alt. |
1014 | */ |
1015 | static const struct input_device_id sysrq_ids[] = { |
1016 | { |
1017 | .flags = INPUT_DEVICE_ID_MATCH_EVBIT | |
1018 | INPUT_DEVICE_ID_MATCH_KEYBIT, |
1019 | .evbit = { [BIT_WORD(EV_KEY)] = BIT_MASK(EV_KEY) }, |
1020 | .keybit = { [BIT_WORD(KEY_LEFTALT)] = BIT_MASK(KEY_LEFTALT) }, |
1021 | }, |
1022 | { }, |
1023 | }; |
1024 | |
1025 | static struct input_handler sysrq_handler = { |
1026 | .filter = sysrq_filter, |
1027 | .connect = sysrq_connect, |
1028 | .disconnect = sysrq_disconnect, |
1029 | .name = "sysrq" , |
1030 | .id_table = sysrq_ids, |
1031 | }; |
1032 | |
1033 | static inline void sysrq_register_handler(void) |
1034 | { |
1035 | int error; |
1036 | |
1037 | sysrq_of_get_keyreset_config(); |
1038 | |
1039 | error = input_register_handler(&sysrq_handler); |
1040 | if (error) |
1041 | pr_err("Failed to register input handler, error %d" , error); |
1042 | } |
1043 | |
1044 | static inline void sysrq_unregister_handler(void) |
1045 | { |
1046 | input_unregister_handler(&sysrq_handler); |
1047 | } |
1048 | |
1049 | static int sysrq_reset_seq_param_set(const char *buffer, |
1050 | const struct kernel_param *kp) |
1051 | { |
1052 | unsigned long val; |
1053 | int error; |
1054 | |
1055 | error = kstrtoul(s: buffer, base: 0, res: &val); |
1056 | if (error < 0) |
1057 | return error; |
1058 | |
1059 | if (val > KEY_MAX) |
1060 | return -EINVAL; |
1061 | |
1062 | *((unsigned short *)kp->arg) = val; |
1063 | sysrq_reset_seq_version++; |
1064 | |
1065 | return 0; |
1066 | } |
1067 | |
1068 | static const struct kernel_param_ops param_ops_sysrq_reset_seq = { |
1069 | .get = param_get_ushort, |
1070 | .set = sysrq_reset_seq_param_set, |
1071 | }; |
1072 | |
1073 | #define param_check_sysrq_reset_seq(name, p) \ |
1074 | __param_check(name, p, unsigned short) |
1075 | |
1076 | /* |
1077 | * not really modular, but the easiest way to keep compat with existing |
1078 | * bootargs behaviour is to continue using module_param here. |
1079 | */ |
1080 | module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq, |
1081 | &sysrq_reset_seq_len, 0644); |
1082 | |
1083 | module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644); |
1084 | |
1085 | #else |
1086 | |
1087 | static inline void sysrq_register_handler(void) |
1088 | { |
1089 | } |
1090 | |
1091 | static inline void sysrq_unregister_handler(void) |
1092 | { |
1093 | } |
1094 | |
1095 | #endif /* CONFIG_INPUT */ |
1096 | |
1097 | int sysrq_toggle_support(int enable_mask) |
1098 | { |
1099 | bool was_enabled = sysrq_on(); |
1100 | |
1101 | sysrq_enabled = enable_mask; |
1102 | |
1103 | if (was_enabled != sysrq_on()) { |
1104 | if (sysrq_on()) |
1105 | sysrq_register_handler(); |
1106 | else |
1107 | sysrq_unregister_handler(); |
1108 | } |
1109 | |
1110 | return 0; |
1111 | } |
1112 | EXPORT_SYMBOL_GPL(sysrq_toggle_support); |
1113 | |
1114 | static int __sysrq_swap_key_ops(u8 key, const struct sysrq_key_op *insert_op_p, |
1115 | const struct sysrq_key_op *remove_op_p) |
1116 | { |
1117 | int retval; |
1118 | |
1119 | spin_lock(lock: &sysrq_key_table_lock); |
1120 | if (__sysrq_get_key_op(key) == remove_op_p) { |
1121 | __sysrq_put_key_op(key, op_p: insert_op_p); |
1122 | retval = 0; |
1123 | } else { |
1124 | retval = -1; |
1125 | } |
1126 | spin_unlock(lock: &sysrq_key_table_lock); |
1127 | |
1128 | /* |
1129 | * A concurrent __handle_sysrq either got the old op or the new op. |
1130 | * Wait for it to go away before returning, so the code for an old |
1131 | * op is not freed (eg. on module unload) while it is in use. |
1132 | */ |
1133 | synchronize_rcu(); |
1134 | |
1135 | return retval; |
1136 | } |
1137 | |
1138 | int register_sysrq_key(u8 key, const struct sysrq_key_op *op_p) |
1139 | { |
1140 | return __sysrq_swap_key_ops(key, insert_op_p: op_p, NULL); |
1141 | } |
1142 | EXPORT_SYMBOL(register_sysrq_key); |
1143 | |
1144 | int unregister_sysrq_key(u8 key, const struct sysrq_key_op *op_p) |
1145 | { |
1146 | return __sysrq_swap_key_ops(key, NULL, remove_op_p: op_p); |
1147 | } |
1148 | EXPORT_SYMBOL(unregister_sysrq_key); |
1149 | |
1150 | #ifdef CONFIG_PROC_FS |
1151 | /* |
1152 | * writing 'C' to /proc/sysrq-trigger is like sysrq-C |
1153 | */ |
1154 | static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf, |
1155 | size_t count, loff_t *ppos) |
1156 | { |
1157 | if (count) { |
1158 | char c; |
1159 | |
1160 | if (get_user(c, buf)) |
1161 | return -EFAULT; |
1162 | __handle_sysrq(key: c, check_mask: false); |
1163 | } |
1164 | |
1165 | return count; |
1166 | } |
1167 | |
1168 | static const struct proc_ops sysrq_trigger_proc_ops = { |
1169 | .proc_write = write_sysrq_trigger, |
1170 | .proc_lseek = noop_llseek, |
1171 | }; |
1172 | |
1173 | static void sysrq_init_procfs(void) |
1174 | { |
1175 | if (!proc_create(name: "sysrq-trigger" , S_IWUSR, NULL, |
1176 | proc_ops: &sysrq_trigger_proc_ops)) |
1177 | pr_err("Failed to register proc interface\n" ); |
1178 | } |
1179 | |
1180 | #else |
1181 | |
1182 | static inline void sysrq_init_procfs(void) |
1183 | { |
1184 | } |
1185 | |
1186 | #endif /* CONFIG_PROC_FS */ |
1187 | |
1188 | static int __init sysrq_init(void) |
1189 | { |
1190 | sysrq_init_procfs(); |
1191 | |
1192 | if (sysrq_on()) |
1193 | sysrq_register_handler(); |
1194 | |
1195 | return 0; |
1196 | } |
1197 | device_initcall(sysrq_init); |
1198 | |