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/quotaops.h>
28 #include <linux/perf_counter.h>
29 #include <linux/kernel.h>
30 #include <linux/module.h>
31 #include <linux/suspend.h>
32 #include <linux/writeback.h>
33 #include <linux/buffer_head.h> /* for fsync_bdev() */
34 #include <linux/swap.h>
35 #include <linux/spinlock.h>
36 #include <linux/vt_kern.h>
37 #include <linux/workqueue.h>
38 #include <linux/kexec.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 */
125 static void sysrq_handle_crashdump(int key
, struct tty_struct
*tty
)
127 crash_kexec(get_irq_regs());
129 static struct sysrq_key_op sysrq_crashdump_op
= {
130 .handler
= sysrq_handle_crashdump
,
131 .help_msg
= "Crashdump",
132 .action_msg
= "Trigger a crashdump",
133 .enable_mask
= SYSRQ_ENABLE_DUMP
,
136 #define sysrq_crashdump_op (*(struct sysrq_key_op *)0)
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
)
226 struct pt_regs
*regs
= get_irq_regs();
228 printk(KERN_INFO
"CPU%d:\n", smp_processor_id());
231 schedule_work(&sysrq_showallcpus
);
234 static struct sysrq_key_op sysrq_showallcpus_op
= {
235 .handler
= sysrq_handle_showallcpus
,
236 .help_msg
= "show-backtrace-all-active-cpus(L)",
237 .action_msg
= "Show backtrace of all active CPUs",
238 .enable_mask
= SYSRQ_ENABLE_DUMP
,
242 static void sysrq_handle_showregs(int key
, struct tty_struct
*tty
)
244 struct pt_regs
*regs
= get_irq_regs();
247 perf_counter_print_debug();
249 static struct sysrq_key_op sysrq_showregs_op
= {
250 .handler
= sysrq_handle_showregs
,
251 .help_msg
= "show-registers(P)",
252 .action_msg
= "Show Regs",
253 .enable_mask
= SYSRQ_ENABLE_DUMP
,
256 static void sysrq_handle_showstate(int key
, struct tty_struct
*tty
)
260 static struct sysrq_key_op sysrq_showstate_op
= {
261 .handler
= sysrq_handle_showstate
,
262 .help_msg
= "show-task-states(T)",
263 .action_msg
= "Show State",
264 .enable_mask
= SYSRQ_ENABLE_DUMP
,
267 static void sysrq_handle_showstate_blocked(int key
, struct tty_struct
*tty
)
269 show_state_filter(TASK_UNINTERRUPTIBLE
);
271 static struct sysrq_key_op sysrq_showstate_blocked_op
= {
272 .handler
= sysrq_handle_showstate_blocked
,
273 .help_msg
= "show-blocked-tasks(W)",
274 .action_msg
= "Show Blocked State",
275 .enable_mask
= SYSRQ_ENABLE_DUMP
,
278 #ifdef CONFIG_TRACING
279 #include <linux/ftrace.h>
281 static void sysrq_ftrace_dump(int key
, struct tty_struct
*tty
)
285 static struct sysrq_key_op sysrq_ftrace_dump_op
= {
286 .handler
= sysrq_ftrace_dump
,
287 .help_msg
= "dump-ftrace-buffer(Z)",
288 .action_msg
= "Dump ftrace buffer",
289 .enable_mask
= SYSRQ_ENABLE_DUMP
,
292 #define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)0)
295 static void sysrq_handle_showmem(int key
, struct tty_struct
*tty
)
299 static struct sysrq_key_op sysrq_showmem_op
= {
300 .handler
= sysrq_handle_showmem
,
301 .help_msg
= "show-memory-usage(M)",
302 .action_msg
= "Show Memory",
303 .enable_mask
= SYSRQ_ENABLE_DUMP
,
307 * Signal sysrq helper function. Sends a signal to all user processes.
309 static void send_sig_all(int sig
)
311 struct task_struct
*p
;
313 for_each_process(p
) {
314 if (p
->mm
&& !is_global_init(p
))
315 /* Not swapper, init nor kernel thread */
320 static void sysrq_handle_term(int key
, struct tty_struct
*tty
)
322 send_sig_all(SIGTERM
);
323 console_loglevel
= 8;
325 static struct sysrq_key_op sysrq_term_op
= {
326 .handler
= sysrq_handle_term
,
327 .help_msg
= "terminate-all-tasks(E)",
328 .action_msg
= "Terminate All Tasks",
329 .enable_mask
= SYSRQ_ENABLE_SIGNAL
,
332 static void moom_callback(struct work_struct
*ignored
)
334 out_of_memory(node_zonelist(0, GFP_KERNEL
), GFP_KERNEL
, 0);
337 static DECLARE_WORK(moom_work
, moom_callback
);
339 static void sysrq_handle_moom(int key
, struct tty_struct
*tty
)
341 schedule_work(&moom_work
);
343 static struct sysrq_key_op sysrq_moom_op
= {
344 .handler
= sysrq_handle_moom
,
345 .help_msg
= "memory-full-oom-kill(F)",
346 .action_msg
= "Manual OOM execution",
347 .enable_mask
= SYSRQ_ENABLE_SIGNAL
,
351 static void sysrq_handle_thaw(int key
, struct tty_struct
*tty
)
353 emergency_thaw_all();
355 static struct sysrq_key_op sysrq_thaw_op
= {
356 .handler
= sysrq_handle_thaw
,
357 .help_msg
= "thaw-filesystems(J)",
358 .action_msg
= "Emergency Thaw of all frozen filesystems",
359 .enable_mask
= SYSRQ_ENABLE_SIGNAL
,
363 static void sysrq_handle_kill(int key
, struct tty_struct
*tty
)
365 send_sig_all(SIGKILL
);
366 console_loglevel
= 8;
368 static struct sysrq_key_op sysrq_kill_op
= {
369 .handler
= sysrq_handle_kill
,
370 .help_msg
= "kill-all-tasks(I)",
371 .action_msg
= "Kill All Tasks",
372 .enable_mask
= SYSRQ_ENABLE_SIGNAL
,
375 static void sysrq_handle_unrt(int key
, struct tty_struct
*tty
)
377 normalize_rt_tasks();
379 static struct sysrq_key_op sysrq_unrt_op
= {
380 .handler
= sysrq_handle_unrt
,
381 .help_msg
= "nice-all-RT-tasks(N)",
382 .action_msg
= "Nice All RT Tasks",
383 .enable_mask
= SYSRQ_ENABLE_RTNICE
,
386 /* Key Operations table and lock */
387 static DEFINE_SPINLOCK(sysrq_key_table_lock
);
389 static struct sysrq_key_op
*sysrq_key_table
[36] = {
390 &sysrq_loglevel_op
, /* 0 */
391 &sysrq_loglevel_op
, /* 1 */
392 &sysrq_loglevel_op
, /* 2 */
393 &sysrq_loglevel_op
, /* 3 */
394 &sysrq_loglevel_op
, /* 4 */
395 &sysrq_loglevel_op
, /* 5 */
396 &sysrq_loglevel_op
, /* 6 */
397 &sysrq_loglevel_op
, /* 7 */
398 &sysrq_loglevel_op
, /* 8 */
399 &sysrq_loglevel_op
, /* 9 */
402 * a: Don't use for system provided sysrqs, it is handled specially on
403 * sparc and will never arrive.
406 &sysrq_reboot_op
, /* b */
407 &sysrq_crashdump_op
, /* c & ibm_emac driver debug */
408 &sysrq_showlocks_op
, /* d */
409 &sysrq_term_op
, /* e */
410 &sysrq_moom_op
, /* f */
411 /* g: May be registered for the kernel debugger */
413 NULL
, /* h - reserved for help */
414 &sysrq_kill_op
, /* i */
416 &sysrq_thaw_op
, /* j */
420 &sysrq_SAK_op
, /* k */
422 &sysrq_showallcpus_op
, /* l */
426 &sysrq_showmem_op
, /* m */
427 &sysrq_unrt_op
, /* n */
428 /* o: This will often be registered as 'Off' at init time */
430 &sysrq_showregs_op
, /* p */
431 &sysrq_show_timers_op
, /* q */
432 &sysrq_unraw_op
, /* r */
433 &sysrq_sync_op
, /* s */
434 &sysrq_showstate_op
, /* t */
435 &sysrq_mountro_op
, /* u */
436 /* v: May be registered for frame buffer console restore */
438 &sysrq_showstate_blocked_op
, /* w */
439 /* x: May be registered on ppc/powerpc for xmon */
441 /* y: May be registered on sparc64 for global register dump */
443 &sysrq_ftrace_dump_op
, /* z */
446 /* key2index calculation, -1 on invalid index */
447 static int sysrq_key_table_key2index(int key
)
451 if ((key
>= '0') && (key
<= '9'))
453 else if ((key
>= 'a') && (key
<= 'z'))
454 retval
= key
+ 10 - 'a';
461 * get and put functions for the table, exposed to modules.
463 struct sysrq_key_op
*__sysrq_get_key_op(int key
)
465 struct sysrq_key_op
*op_p
= NULL
;
468 i
= sysrq_key_table_key2index(key
);
470 op_p
= sysrq_key_table
[i
];
474 static void __sysrq_put_key_op(int key
, struct sysrq_key_op
*op_p
)
476 int i
= sysrq_key_table_key2index(key
);
479 sysrq_key_table
[i
] = op_p
;
483 * This is the non-locking version of handle_sysrq. It must/can only be called
484 * by sysrq key handlers, as they are inside of the lock
486 void __handle_sysrq(int key
, struct tty_struct
*tty
, int check_mask
)
488 struct sysrq_key_op
*op_p
;
493 spin_lock_irqsave(&sysrq_key_table_lock
, flags
);
495 * Raise the apparent loglevel to maximum so that the sysrq header
496 * is shown to provide the user with positive feedback. We do not
497 * simply emit this at KERN_EMERG as that would change message
498 * routing in the consumers of /proc/kmsg.
500 orig_log_level
= console_loglevel
;
501 console_loglevel
= 7;
502 printk(KERN_INFO
"SysRq : ");
504 op_p
= __sysrq_get_key_op(key
);
507 * Should we check for enabled operations (/proc/sysrq-trigger
508 * should not) and is the invoked operation enabled?
510 if (!check_mask
|| sysrq_on_mask(op_p
->enable_mask
)) {
511 printk("%s\n", op_p
->action_msg
);
512 console_loglevel
= orig_log_level
;
513 op_p
->handler(key
, tty
);
515 printk("This sysrq operation is disabled.\n");
519 /* Only print the help msg once per handler */
520 for (i
= 0; i
< ARRAY_SIZE(sysrq_key_table
); i
++) {
521 if (sysrq_key_table
[i
]) {
524 for (j
= 0; sysrq_key_table
[i
] !=
525 sysrq_key_table
[j
]; j
++)
529 printk("%s ", sysrq_key_table
[i
]->help_msg
);
533 console_loglevel
= orig_log_level
;
535 spin_unlock_irqrestore(&sysrq_key_table_lock
, flags
);
539 * This function is called by the keyboard handler when SysRq is pressed
540 * and any other keycode arrives.
542 void handle_sysrq(int key
, struct tty_struct
*tty
)
545 __handle_sysrq(key
, tty
, 1);
547 EXPORT_SYMBOL(handle_sysrq
);
549 static int __sysrq_swap_key_ops(int key
, struct sysrq_key_op
*insert_op_p
,
550 struct sysrq_key_op
*remove_op_p
)
556 spin_lock_irqsave(&sysrq_key_table_lock
, flags
);
557 if (__sysrq_get_key_op(key
) == remove_op_p
) {
558 __sysrq_put_key_op(key
, insert_op_p
);
563 spin_unlock_irqrestore(&sysrq_key_table_lock
, flags
);
567 int register_sysrq_key(int key
, struct sysrq_key_op
*op_p
)
569 return __sysrq_swap_key_ops(key
, op_p
, NULL
);
571 EXPORT_SYMBOL(register_sysrq_key
);
573 int unregister_sysrq_key(int key
, struct sysrq_key_op
*op_p
)
575 return __sysrq_swap_key_ops(key
, NULL
, op_p
);
577 EXPORT_SYMBOL(unregister_sysrq_key
);
579 #ifdef CONFIG_PROC_FS
581 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
583 static ssize_t
write_sysrq_trigger(struct file
*file
, const char __user
*buf
,
584 size_t count
, loff_t
*ppos
)
589 if (get_user(c
, buf
))
591 __handle_sysrq(c
, NULL
, 0);
596 static const struct file_operations proc_sysrq_trigger_operations
= {
597 .write
= write_sysrq_trigger
,
600 static int __init
sysrq_init(void)
602 proc_create("sysrq-trigger", S_IWUSR
, NULL
, &proc_sysrq_trigger_operations
);
605 module_init(sysrq_init
);