3 * $Id: sysrq.c,v 1.15 1998/08/23 14:56:41 mj Exp $
5 * Linux Magic System Request Key Hacks
7 * (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
8 * based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz>
10 * (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
11 * overhauled to use key registration
12 * based upon discusions in irc://irc.openprojects.net/#kernelnewbies
15 #include <linux/sched.h>
16 #include <linux/interrupt.h>
19 #include <linux/tty.h>
20 #include <linux/mount.h>
21 #include <linux/kdev_t.h>
22 #include <linux/major.h>
23 #include <linux/reboot.h>
24 #include <linux/sysrq.h>
25 #include <linux/kbd_kern.h>
26 #include <linux/proc_fs.h>
27 #include <linux/nmi.h>
28 #include <linux/quotaops.h>
29 #include <linux/perf_event.h>
30 #include <linux/kernel.h>
31 #include <linux/module.h>
32 #include <linux/suspend.h>
33 #include <linux/writeback.h>
34 #include <linux/buffer_head.h> /* for fsync_bdev() */
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>
42 #include <asm/ptrace.h>
43 #include <asm/irq_regs.h>
45 /* Whether we react on sysrq keys or just ignore them */
46 int __read_mostly __sysrq_enabled = 1;
48 static int __read_mostly sysrq_always_enabled;
52 return __sysrq_enabled || sysrq_always_enabled;
56 * A value of 1 means 'all', other nonzero values are an op mask:
58 static inline int sysrq_on_mask(int mask)
60 return sysrq_always_enabled || __sysrq_enabled == 1 ||
61 (__sysrq_enabled & mask);
64 static int __init sysrq_always_enabled_setup(char *str)
66 sysrq_always_enabled = 1;
67 printk(KERN_INFO "debug: sysrq always enabled.\n");
72 __setup("sysrq_always_enabled", sysrq_always_enabled_setup);
75 static void sysrq_handle_loglevel(int key, struct tty_struct *tty)
80 printk("Loglevel set to %d\n", i);
83 static struct sysrq_key_op sysrq_loglevel_op = {
84 .handler = sysrq_handle_loglevel,
85 .help_msg = "loglevel(0-9)",
86 .action_msg = "Changing Loglevel",
87 .enable_mask = SYSRQ_ENABLE_LOG,
91 static void sysrq_handle_SAK(int key, struct tty_struct *tty)
93 struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
94 schedule_work(SAK_work);
96 static struct sysrq_key_op sysrq_SAK_op = {
97 .handler = sysrq_handle_SAK,
100 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
103 #define sysrq_SAK_op (*(struct sysrq_key_op *)0)
107 static void sysrq_handle_unraw(int key, struct tty_struct *tty)
109 struct kbd_struct *kbd = &kbd_table[fg_console];
112 kbd->kbdmode = default_utf8 ? VC_UNICODE : VC_XLATE;
114 static struct sysrq_key_op sysrq_unraw_op = {
115 .handler = sysrq_handle_unraw,
117 .action_msg = "Keyboard mode set to system default",
118 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
121 #define sysrq_unraw_op (*(struct sysrq_key_op *)0)
122 #endif /* CONFIG_VT */
124 static void sysrq_handle_crash(int key, struct tty_struct *tty)
128 panic_on_oops = 1; /* force panic */
132 static struct sysrq_key_op sysrq_crash_op = {
133 .handler = sysrq_handle_crash,
135 .action_msg = "Trigger a crash",
136 .enable_mask = SYSRQ_ENABLE_DUMP,
139 static void sysrq_handle_reboot(int key, struct tty_struct *tty)
145 static struct sysrq_key_op sysrq_reboot_op = {
146 .handler = sysrq_handle_reboot,
147 .help_msg = "reBoot",
148 .action_msg = "Resetting",
149 .enable_mask = SYSRQ_ENABLE_BOOT,
152 static void sysrq_handle_sync(int key, struct tty_struct *tty)
156 static struct sysrq_key_op sysrq_sync_op = {
157 .handler = sysrq_handle_sync,
159 .action_msg = "Emergency Sync",
160 .enable_mask = SYSRQ_ENABLE_SYNC,
163 static void sysrq_handle_show_timers(int key, struct tty_struct *tty)
165 sysrq_timer_list_show();
168 static struct sysrq_key_op sysrq_show_timers_op = {
169 .handler = sysrq_handle_show_timers,
170 .help_msg = "show-all-timers(Q)",
171 .action_msg = "Show clockevent devices & pending hrtimers (no others)",
174 static void sysrq_handle_mountro(int key, struct tty_struct *tty)
178 static struct sysrq_key_op sysrq_mountro_op = {
179 .handler = sysrq_handle_mountro,
180 .help_msg = "Unmount",
181 .action_msg = "Emergency Remount R/O",
182 .enable_mask = SYSRQ_ENABLE_REMOUNT,
185 #ifdef CONFIG_LOCKDEP
186 static void sysrq_handle_showlocks(int key, struct tty_struct *tty)
188 debug_show_all_locks();
191 static struct sysrq_key_op sysrq_showlocks_op = {
192 .handler = sysrq_handle_showlocks,
193 .help_msg = "show-all-locks(D)",
194 .action_msg = "Show Locks Held",
197 #define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
201 static DEFINE_SPINLOCK(show_lock);
203 static void showacpu(void *dummy)
207 /* Idle CPUs have no interesting backtrace. */
208 if (idle_cpu(smp_processor_id()))
211 spin_lock_irqsave(&show_lock, flags);
212 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
213 show_stack(NULL, NULL);
214 spin_unlock_irqrestore(&show_lock, flags);
217 static void sysrq_showregs_othercpus(struct work_struct *dummy)
219 smp_call_function(showacpu, NULL, 0);
222 static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
224 static void sysrq_handle_showallcpus(int key, struct tty_struct *tty)
227 * Fall back to the workqueue based printing if the
228 * backtrace printing did not succeed or the
229 * architecture has no support for it:
231 if (!trigger_all_cpu_backtrace()) {
232 struct pt_regs *regs = get_irq_regs();
235 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
238 schedule_work(&sysrq_showallcpus);
242 static struct sysrq_key_op sysrq_showallcpus_op = {
243 .handler = sysrq_handle_showallcpus,
244 .help_msg = "show-backtrace-all-active-cpus(L)",
245 .action_msg = "Show backtrace of all active CPUs",
246 .enable_mask = SYSRQ_ENABLE_DUMP,
250 static void sysrq_handle_showregs(int key, struct tty_struct *tty)
252 struct pt_regs *regs = get_irq_regs();
255 perf_event_print_debug();
257 static struct sysrq_key_op sysrq_showregs_op = {
258 .handler = sysrq_handle_showregs,
259 .help_msg = "show-registers(P)",
260 .action_msg = "Show Regs",
261 .enable_mask = SYSRQ_ENABLE_DUMP,
264 static void sysrq_handle_showstate(int key, struct tty_struct *tty)
268 static struct sysrq_key_op sysrq_showstate_op = {
269 .handler = sysrq_handle_showstate,
270 .help_msg = "show-task-states(T)",
271 .action_msg = "Show State",
272 .enable_mask = SYSRQ_ENABLE_DUMP,
275 static void sysrq_handle_showstate_blocked(int key, struct tty_struct *tty)
277 show_state_filter(TASK_UNINTERRUPTIBLE);
279 static struct sysrq_key_op sysrq_showstate_blocked_op = {
280 .handler = sysrq_handle_showstate_blocked,
281 .help_msg = "show-blocked-tasks(W)",
282 .action_msg = "Show Blocked State",
283 .enable_mask = SYSRQ_ENABLE_DUMP,
286 #ifdef CONFIG_TRACING
287 #include <linux/ftrace.h>
289 static void sysrq_ftrace_dump(int key, struct tty_struct *tty)
293 static struct sysrq_key_op sysrq_ftrace_dump_op = {
294 .handler = sysrq_ftrace_dump,
295 .help_msg = "dump-ftrace-buffer(Z)",
296 .action_msg = "Dump ftrace buffer",
297 .enable_mask = SYSRQ_ENABLE_DUMP,
300 #define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)0)
303 static void sysrq_handle_showmem(int key, struct tty_struct *tty)
307 static struct sysrq_key_op sysrq_showmem_op = {
308 .handler = sysrq_handle_showmem,
309 .help_msg = "show-memory-usage(M)",
310 .action_msg = "Show Memory",
311 .enable_mask = SYSRQ_ENABLE_DUMP,
315 * Signal sysrq helper function. Sends a signal to all user processes.
317 static void send_sig_all(int sig)
319 struct task_struct *p;
321 for_each_process(p) {
322 if (p->mm && !is_global_init(p))
323 /* Not swapper, init nor kernel thread */
328 static void sysrq_handle_term(int key, struct tty_struct *tty)
330 send_sig_all(SIGTERM);
331 console_loglevel = 8;
333 static struct sysrq_key_op sysrq_term_op = {
334 .handler = sysrq_handle_term,
335 .help_msg = "terminate-all-tasks(E)",
336 .action_msg = "Terminate All Tasks",
337 .enable_mask = SYSRQ_ENABLE_SIGNAL,
340 static void moom_callback(struct work_struct *ignored)
342 out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0, NULL);
345 static DECLARE_WORK(moom_work, moom_callback);
347 static void sysrq_handle_moom(int key, struct tty_struct *tty)
349 schedule_work(&moom_work);
351 static struct sysrq_key_op sysrq_moom_op = {
352 .handler = sysrq_handle_moom,
353 .help_msg = "memory-full-oom-kill(F)",
354 .action_msg = "Manual OOM execution",
355 .enable_mask = SYSRQ_ENABLE_SIGNAL,
359 static void sysrq_handle_thaw(int key, struct tty_struct *tty)
361 emergency_thaw_all();
363 static struct sysrq_key_op sysrq_thaw_op = {
364 .handler = sysrq_handle_thaw,
365 .help_msg = "thaw-filesystems(J)",
366 .action_msg = "Emergency Thaw of all frozen filesystems",
367 .enable_mask = SYSRQ_ENABLE_SIGNAL,
371 static void sysrq_handle_kill(int key, struct tty_struct *tty)
373 send_sig_all(SIGKILL);
374 console_loglevel = 8;
376 static struct sysrq_key_op sysrq_kill_op = {
377 .handler = sysrq_handle_kill,
378 .help_msg = "kill-all-tasks(I)",
379 .action_msg = "Kill All Tasks",
380 .enable_mask = SYSRQ_ENABLE_SIGNAL,
383 static void sysrq_handle_unrt(int key, struct tty_struct *tty)
385 normalize_rt_tasks();
387 static struct sysrq_key_op sysrq_unrt_op = {
388 .handler = sysrq_handle_unrt,
389 .help_msg = "nice-all-RT-tasks(N)",
390 .action_msg = "Nice All RT Tasks",
391 .enable_mask = SYSRQ_ENABLE_RTNICE,
394 /* Key Operations table and lock */
395 static DEFINE_SPINLOCK(sysrq_key_table_lock);
397 static struct sysrq_key_op *sysrq_key_table[36] = {
398 &sysrq_loglevel_op, /* 0 */
399 &sysrq_loglevel_op, /* 1 */
400 &sysrq_loglevel_op, /* 2 */
401 &sysrq_loglevel_op, /* 3 */
402 &sysrq_loglevel_op, /* 4 */
403 &sysrq_loglevel_op, /* 5 */
404 &sysrq_loglevel_op, /* 6 */
405 &sysrq_loglevel_op, /* 7 */
406 &sysrq_loglevel_op, /* 8 */
407 &sysrq_loglevel_op, /* 9 */
410 * a: Don't use for system provided sysrqs, it is handled specially on
411 * sparc and will never arrive.
414 &sysrq_reboot_op, /* b */
415 &sysrq_crash_op, /* c & ibm_emac driver debug */
416 &sysrq_showlocks_op, /* d */
417 &sysrq_term_op, /* e */
418 &sysrq_moom_op, /* f */
419 /* g: May be registered for the kernel debugger */
421 NULL, /* h - reserved for help */
422 &sysrq_kill_op, /* i */
424 &sysrq_thaw_op, /* j */
428 &sysrq_SAK_op, /* k */
430 &sysrq_showallcpus_op, /* l */
434 &sysrq_showmem_op, /* m */
435 &sysrq_unrt_op, /* n */
436 /* o: This will often be registered as 'Off' at init time */
438 &sysrq_showregs_op, /* p */
439 &sysrq_show_timers_op, /* q */
440 &sysrq_unraw_op, /* r */
441 &sysrq_sync_op, /* s */
442 &sysrq_showstate_op, /* t */
443 &sysrq_mountro_op, /* u */
444 /* v: May be registered for frame buffer console restore */
446 &sysrq_showstate_blocked_op, /* w */
447 /* x: May be registered on ppc/powerpc for xmon */
449 /* y: May be registered on sparc64 for global register dump */
451 &sysrq_ftrace_dump_op, /* z */
454 /* key2index calculation, -1 on invalid index */
455 static int sysrq_key_table_key2index(int key)
459 if ((key >= '0') && (key <= '9'))
461 else if ((key >= 'a') && (key <= 'z'))
462 retval = key + 10 - 'a';
469 * get and put functions for the table, exposed to modules.
471 struct sysrq_key_op *__sysrq_get_key_op(int key)
473 struct sysrq_key_op *op_p = NULL;
476 i = sysrq_key_table_key2index(key);
478 op_p = sysrq_key_table[i];
482 static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
484 int i = sysrq_key_table_key2index(key);
487 sysrq_key_table[i] = op_p;
491 * This is the non-locking version of handle_sysrq. It must/can only be called
492 * by sysrq key handlers, as they are inside of the lock
494 void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
496 struct sysrq_key_op *op_p;
501 spin_lock_irqsave(&sysrq_key_table_lock, flags);
503 * Raise the apparent loglevel to maximum so that the sysrq header
504 * is shown to provide the user with positive feedback. We do not
505 * simply emit this at KERN_EMERG as that would change message
506 * routing in the consumers of /proc/kmsg.
508 orig_log_level = console_loglevel;
509 console_loglevel = 7;
510 printk(KERN_INFO "SysRq : ");
512 op_p = __sysrq_get_key_op(key);
515 * Should we check for enabled operations (/proc/sysrq-trigger
516 * should not) and is the invoked operation enabled?
518 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
519 printk("%s\n", op_p->action_msg);
520 console_loglevel = orig_log_level;
521 op_p->handler(key, tty);
523 printk("This sysrq operation is disabled.\n");
527 /* Only print the help msg once per handler */
528 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
529 if (sysrq_key_table[i]) {
532 for (j = 0; sysrq_key_table[i] !=
533 sysrq_key_table[j]; j++)
537 printk("%s ", sysrq_key_table[i]->help_msg);
541 console_loglevel = orig_log_level;
543 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
547 * This function is called by the keyboard handler when SysRq is pressed
548 * and any other keycode arrives.
550 void handle_sysrq(int key, struct tty_struct *tty)
553 __handle_sysrq(key, tty, 1);
555 EXPORT_SYMBOL(handle_sysrq);
557 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
558 struct sysrq_key_op *remove_op_p)
564 spin_lock_irqsave(&sysrq_key_table_lock, flags);
565 if (__sysrq_get_key_op(key) == remove_op_p) {
566 __sysrq_put_key_op(key, insert_op_p);
571 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
575 int register_sysrq_key(int key, struct sysrq_key_op *op_p)
577 return __sysrq_swap_key_ops(key, op_p, NULL);
579 EXPORT_SYMBOL(register_sysrq_key);
581 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
583 return __sysrq_swap_key_ops(key, NULL, op_p);
585 EXPORT_SYMBOL(unregister_sysrq_key);
587 #ifdef CONFIG_PROC_FS
589 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
591 static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
592 size_t count, loff_t *ppos)
597 if (get_user(c, buf))
599 __handle_sysrq(c, NULL, 0);
604 static const struct file_operations proc_sysrq_trigger_operations = {
605 .write = write_sysrq_trigger,
608 static int __init sysrq_init(void)
610 proc_create("sysrq-trigger", S_IWUSR, NULL, &proc_sysrq_trigger_operations);
613 module_init(sysrq_init);