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/kernel.h>
29 #include <linux/module.h>
30 #include <linux/suspend.h>
31 #include <linux/writeback.h>
32 #include <linux/buffer_head.h> /* for fsync_bdev() */
33 #include <linux/swap.h>
34 #include <linux/spinlock.h>
35 #include <linux/vt_kern.h>
36 #include <linux/workqueue.h>
37 #include <linux/kexec.h>
38 #include <linux/irq.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
= "loglevel0-8",
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 Pending Timers",
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
= "aLlcpus",
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();
248 static struct sysrq_key_op sysrq_showregs_op
= {
249 .handler
= sysrq_handle_showregs
,
250 .help_msg
= "showPc",
251 .action_msg
= "Show Regs",
252 .enable_mask
= SYSRQ_ENABLE_DUMP
,
255 static void sysrq_handle_showstate(int key
, struct tty_struct
*tty
)
259 static struct sysrq_key_op sysrq_showstate_op
= {
260 .handler
= sysrq_handle_showstate
,
261 .help_msg
= "showTasks",
262 .action_msg
= "Show State",
263 .enable_mask
= SYSRQ_ENABLE_DUMP
,
266 static void sysrq_handle_showstate_blocked(int key
, struct tty_struct
*tty
)
268 show_state_filter(TASK_UNINTERRUPTIBLE
);
270 static struct sysrq_key_op sysrq_showstate_blocked_op
= {
271 .handler
= sysrq_handle_showstate_blocked
,
272 .help_msg
= "shoW-blocked-tasks",
273 .action_msg
= "Show Blocked State",
274 .enable_mask
= SYSRQ_ENABLE_DUMP
,
278 static void sysrq_handle_showmem(int key
, struct tty_struct
*tty
)
282 static struct sysrq_key_op sysrq_showmem_op
= {
283 .handler
= sysrq_handle_showmem
,
284 .help_msg
= "showMem",
285 .action_msg
= "Show Memory",
286 .enable_mask
= SYSRQ_ENABLE_DUMP
,
290 * Signal sysrq helper function. Sends a signal to all user processes.
292 static void send_sig_all(int sig
)
294 struct task_struct
*p
;
296 for_each_process(p
) {
297 if (p
->mm
&& !is_global_init(p
))
298 /* Not swapper, init nor kernel thread */
303 static void sysrq_handle_term(int key
, struct tty_struct
*tty
)
305 send_sig_all(SIGTERM
);
306 console_loglevel
= 8;
308 static struct sysrq_key_op sysrq_term_op
= {
309 .handler
= sysrq_handle_term
,
311 .action_msg
= "Terminate All Tasks",
312 .enable_mask
= SYSRQ_ENABLE_SIGNAL
,
315 static void moom_callback(struct work_struct
*ignored
)
317 out_of_memory(node_zonelist(0, GFP_KERNEL
), GFP_KERNEL
, 0);
320 static DECLARE_WORK(moom_work
, moom_callback
);
322 static void sysrq_handle_moom(int key
, struct tty_struct
*tty
)
324 schedule_work(&moom_work
);
326 static struct sysrq_key_op sysrq_moom_op
= {
327 .handler
= sysrq_handle_moom
,
329 .action_msg
= "Manual OOM execution",
330 .enable_mask
= SYSRQ_ENABLE_SIGNAL
,
333 static void sysrq_handle_kill(int key
, struct tty_struct
*tty
)
335 send_sig_all(SIGKILL
);
336 console_loglevel
= 8;
338 static struct sysrq_key_op sysrq_kill_op
= {
339 .handler
= sysrq_handle_kill
,
341 .action_msg
= "Kill All Tasks",
342 .enable_mask
= SYSRQ_ENABLE_SIGNAL
,
345 static void sysrq_handle_unrt(int key
, struct tty_struct
*tty
)
347 normalize_rt_tasks();
349 static struct sysrq_key_op sysrq_unrt_op
= {
350 .handler
= sysrq_handle_unrt
,
352 .action_msg
= "Nice All RT Tasks",
353 .enable_mask
= SYSRQ_ENABLE_RTNICE
,
356 /* Key Operations table and lock */
357 static DEFINE_SPINLOCK(sysrq_key_table_lock
);
359 static struct sysrq_key_op
*sysrq_key_table
[36] = {
360 &sysrq_loglevel_op
, /* 0 */
361 &sysrq_loglevel_op
, /* 1 */
362 &sysrq_loglevel_op
, /* 2 */
363 &sysrq_loglevel_op
, /* 3 */
364 &sysrq_loglevel_op
, /* 4 */
365 &sysrq_loglevel_op
, /* 5 */
366 &sysrq_loglevel_op
, /* 6 */
367 &sysrq_loglevel_op
, /* 7 */
368 &sysrq_loglevel_op
, /* 8 */
369 &sysrq_loglevel_op
, /* 9 */
372 * a: Don't use for system provided sysrqs, it is handled specially on
373 * sparc and will never arrive.
376 &sysrq_reboot_op
, /* b */
377 &sysrq_crashdump_op
, /* c & ibm_emac driver debug */
378 &sysrq_showlocks_op
, /* d */
379 &sysrq_term_op
, /* e */
380 &sysrq_moom_op
, /* f */
381 /* g: May be registered by ppc for kgdb */
384 &sysrq_kill_op
, /* i */
386 &sysrq_SAK_op
, /* k */
388 &sysrq_showallcpus_op
, /* l */
392 &sysrq_showmem_op
, /* m */
393 &sysrq_unrt_op
, /* n */
394 /* o: This will often be registered as 'Off' at init time */
396 &sysrq_showregs_op
, /* p */
397 &sysrq_show_timers_op
, /* q */
398 &sysrq_unraw_op
, /* r */
399 &sysrq_sync_op
, /* s */
400 &sysrq_showstate_op
, /* t */
401 &sysrq_mountro_op
, /* u */
402 /* v: May be registered at init time by SMP VOYAGER */
404 &sysrq_showstate_blocked_op
, /* w */
405 /* x: May be registered on ppc/powerpc for xmon */
407 /* y: May be registered on sparc64 for global register dump */
412 /* key2index calculation, -1 on invalid index */
413 static int sysrq_key_table_key2index(int key
)
417 if ((key
>= '0') && (key
<= '9'))
419 else if ((key
>= 'a') && (key
<= 'z'))
420 retval
= key
+ 10 - 'a';
427 * get and put functions for the table, exposed to modules.
429 struct sysrq_key_op
*__sysrq_get_key_op(int key
)
431 struct sysrq_key_op
*op_p
= NULL
;
434 i
= sysrq_key_table_key2index(key
);
436 op_p
= sysrq_key_table
[i
];
440 static void __sysrq_put_key_op(int key
, struct sysrq_key_op
*op_p
)
442 int i
= sysrq_key_table_key2index(key
);
445 sysrq_key_table
[i
] = op_p
;
449 * This is the non-locking version of handle_sysrq. It must/can only be called
450 * by sysrq key handlers, as they are inside of the lock
452 void __handle_sysrq(int key
, struct tty_struct
*tty
, int check_mask
)
454 struct sysrq_key_op
*op_p
;
459 spin_lock_irqsave(&sysrq_key_table_lock
, flags
);
460 orig_log_level
= console_loglevel
;
461 console_loglevel
= 7;
462 printk(KERN_INFO
"SysRq : ");
464 op_p
= __sysrq_get_key_op(key
);
467 * Should we check for enabled operations (/proc/sysrq-trigger
468 * should not) and is the invoked operation enabled?
470 if (!check_mask
|| sysrq_on_mask(op_p
->enable_mask
)) {
471 printk("%s\n", op_p
->action_msg
);
472 console_loglevel
= orig_log_level
;
473 op_p
->handler(key
, tty
);
475 printk("This sysrq operation is disabled.\n");
479 /* Only print the help msg once per handler */
480 for (i
= 0; i
< ARRAY_SIZE(sysrq_key_table
); i
++) {
481 if (sysrq_key_table
[i
]) {
484 for (j
= 0; sysrq_key_table
[i
] !=
485 sysrq_key_table
[j
]; j
++)
489 printk("%s ", sysrq_key_table
[i
]->help_msg
);
493 console_loglevel
= orig_log_level
;
495 spin_unlock_irqrestore(&sysrq_key_table_lock
, flags
);
499 * This function is called by the keyboard handler when SysRq is pressed
500 * and any other keycode arrives.
502 void handle_sysrq(int key
, struct tty_struct
*tty
)
505 __handle_sysrq(key
, tty
, 1);
507 EXPORT_SYMBOL(handle_sysrq
);
509 static int __sysrq_swap_key_ops(int key
, struct sysrq_key_op
*insert_op_p
,
510 struct sysrq_key_op
*remove_op_p
)
516 spin_lock_irqsave(&sysrq_key_table_lock
, flags
);
517 if (__sysrq_get_key_op(key
) == remove_op_p
) {
518 __sysrq_put_key_op(key
, insert_op_p
);
523 spin_unlock_irqrestore(&sysrq_key_table_lock
, flags
);
527 int register_sysrq_key(int key
, struct sysrq_key_op
*op_p
)
529 return __sysrq_swap_key_ops(key
, op_p
, NULL
);
531 EXPORT_SYMBOL(register_sysrq_key
);
533 int unregister_sysrq_key(int key
, struct sysrq_key_op
*op_p
)
535 return __sysrq_swap_key_ops(key
, NULL
, op_p
);
537 EXPORT_SYMBOL(unregister_sysrq_key
);
539 #ifdef CONFIG_PROC_FS
541 * writing 'C' to /proc/sysrq-trigger is like sysrq-C
543 static ssize_t
write_sysrq_trigger(struct file
*file
, const char __user
*buf
,
544 size_t count
, loff_t
*ppos
)
549 if (get_user(c
, buf
))
551 __handle_sysrq(c
, NULL
, 0);
556 static const struct file_operations proc_sysrq_trigger_operations
= {
557 .write
= write_sysrq_trigger
,
560 static int __init
sysrq_init(void)
562 proc_create("sysrq-trigger", S_IWUSR
, NULL
, &proc_sysrq_trigger_operations
);
565 module_init(sysrq_init
);