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/quotaops.h>
27 #include <linux/smp_lock.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>
39 #include <asm/ptrace.h>
41 /* Whether we react on sysrq keys or just ignore them */
42 int sysrq_enabled = 1;
44 static void sysrq_handle_loglevel(int key, struct pt_regs *pt_regs,
45 struct tty_struct *tty)
50 printk("Loglevel set to %d\n", i);
53 static struct sysrq_key_op sysrq_loglevel_op = {
54 .handler = sysrq_handle_loglevel,
55 .help_msg = "loglevel0-8",
56 .action_msg = "Changing Loglevel",
57 .enable_mask = SYSRQ_ENABLE_LOG,
61 static void sysrq_handle_SAK(int key, struct pt_regs *pt_regs,
62 struct tty_struct *tty)
66 reset_vc(vc_cons[fg_console].d);
68 static struct sysrq_key_op sysrq_SAK_op = {
69 .handler = sysrq_handle_SAK,
72 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
75 #define sysrq_SAK_op (*(struct sysrq_key_op *)0)
79 static void sysrq_handle_unraw(int key, struct pt_regs *pt_regs,
80 struct tty_struct *tty)
82 struct kbd_struct *kbd = &kbd_table[fg_console];
85 kbd->kbdmode = VC_XLATE;
87 static struct sysrq_key_op sysrq_unraw_op = {
88 .handler = sysrq_handle_unraw,
90 .action_msg = "Keyboard mode set to XLATE",
91 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
94 #define sysrq_unraw_op (*(struct sysrq_key_op *)0)
95 #endif /* CONFIG_VT */
97 static void sysrq_handle_crashdump(int key, struct pt_regs *pt_regs,
98 struct tty_struct *tty)
101 crash_kexec(pt_regs);
102 /* can't get here if crash image is loaded */
103 printk("Kexec: Warning: crash image not loaded\n");
106 panic("SysRq-triggered panic!\n");
108 static struct sysrq_key_op sysrq_crashdump_op = {
109 .handler = sysrq_handle_crashdump,
110 .help_msg = "Crashdump",
111 .action_msg = "Trigger a crashdump",
112 .enable_mask = SYSRQ_ENABLE_DUMP,
115 static void sysrq_handle_reboot(int key, struct pt_regs *pt_regs,
116 struct tty_struct *tty)
122 static struct sysrq_key_op sysrq_reboot_op = {
123 .handler = sysrq_handle_reboot,
124 .help_msg = "reBoot",
125 .action_msg = "Resetting",
126 .enable_mask = SYSRQ_ENABLE_BOOT,
129 static void sysrq_handle_sync(int key, struct pt_regs *pt_regs,
130 struct tty_struct *tty)
134 static struct sysrq_key_op sysrq_sync_op = {
135 .handler = sysrq_handle_sync,
137 .action_msg = "Emergency Sync",
138 .enable_mask = SYSRQ_ENABLE_SYNC,
141 static void sysrq_handle_mountro(int key, struct pt_regs *pt_regs,
142 struct tty_struct *tty)
146 static struct sysrq_key_op sysrq_mountro_op = {
147 .handler = sysrq_handle_mountro,
148 .help_msg = "Unmount",
149 .action_msg = "Emergency Remount R/O",
150 .enable_mask = SYSRQ_ENABLE_REMOUNT,
153 #ifdef CONFIG_LOCKDEP
154 static void sysrq_handle_showlocks(int key, struct pt_regs *pt_regs,
155 struct tty_struct *tty)
157 debug_show_all_locks();
160 static struct sysrq_key_op sysrq_showlocks_op = {
161 .handler = sysrq_handle_showlocks,
162 .help_msg = "show-all-locks(D)",
163 .action_msg = "Show Locks Held",
166 #define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
169 static void sysrq_handle_showregs(int key, struct pt_regs *pt_regs,
170 struct tty_struct *tty)
175 static struct sysrq_key_op sysrq_showregs_op = {
176 .handler = sysrq_handle_showregs,
177 .help_msg = "showPc",
178 .action_msg = "Show Regs",
179 .enable_mask = SYSRQ_ENABLE_DUMP,
182 static void sysrq_handle_showstate(int key, struct pt_regs *pt_regs,
183 struct tty_struct *tty)
187 static struct sysrq_key_op sysrq_showstate_op = {
188 .handler = sysrq_handle_showstate,
189 .help_msg = "showTasks",
190 .action_msg = "Show State",
191 .enable_mask = SYSRQ_ENABLE_DUMP,
194 static void sysrq_handle_showmem(int key, struct pt_regs *pt_regs,
195 struct tty_struct *tty)
199 static struct sysrq_key_op sysrq_showmem_op = {
200 .handler = sysrq_handle_showmem,
201 .help_msg = "showMem",
202 .action_msg = "Show Memory",
203 .enable_mask = SYSRQ_ENABLE_DUMP,
207 * Signal sysrq helper function. Sends a signal to all user processes.
209 static void send_sig_all(int sig)
211 struct task_struct *p;
213 for_each_process(p) {
214 if (p->mm && p->pid != 1)
215 /* Not swapper, init nor kernel thread */
220 static void sysrq_handle_term(int key, struct pt_regs *pt_regs,
221 struct tty_struct *tty)
223 send_sig_all(SIGTERM);
224 console_loglevel = 8;
226 static struct sysrq_key_op sysrq_term_op = {
227 .handler = sysrq_handle_term,
229 .action_msg = "Terminate All Tasks",
230 .enable_mask = SYSRQ_ENABLE_SIGNAL,
233 static void moom_callback(void *ignored)
235 out_of_memory(&NODE_DATA(0)->node_zonelists[ZONE_NORMAL],
239 static DECLARE_WORK(moom_work, moom_callback, NULL);
241 static void sysrq_handle_moom(int key, struct pt_regs *pt_regs,
242 struct tty_struct *tty)
244 schedule_work(&moom_work);
246 static struct sysrq_key_op sysrq_moom_op = {
247 .handler = sysrq_handle_moom,
249 .action_msg = "Manual OOM execution",
252 static void sysrq_handle_kill(int key, struct pt_regs *pt_regs,
253 struct tty_struct *tty)
255 send_sig_all(SIGKILL);
256 console_loglevel = 8;
258 static struct sysrq_key_op sysrq_kill_op = {
259 .handler = sysrq_handle_kill,
261 .action_msg = "Kill All Tasks",
262 .enable_mask = SYSRQ_ENABLE_SIGNAL,
265 static void sysrq_handle_unrt(int key, struct pt_regs *pt_regs,
266 struct tty_struct *tty)
268 normalize_rt_tasks();
270 static struct sysrq_key_op sysrq_unrt_op = {
271 .handler = sysrq_handle_unrt,
273 .action_msg = "Nice All RT Tasks",
274 .enable_mask = SYSRQ_ENABLE_RTNICE,
277 /* Key Operations table and lock */
278 static DEFINE_SPINLOCK(sysrq_key_table_lock);
280 static struct sysrq_key_op *sysrq_key_table[36] = {
281 &sysrq_loglevel_op, /* 0 */
282 &sysrq_loglevel_op, /* 1 */
283 &sysrq_loglevel_op, /* 2 */
284 &sysrq_loglevel_op, /* 3 */
285 &sysrq_loglevel_op, /* 4 */
286 &sysrq_loglevel_op, /* 5 */
287 &sysrq_loglevel_op, /* 6 */
288 &sysrq_loglevel_op, /* 7 */
289 &sysrq_loglevel_op, /* 8 */
290 &sysrq_loglevel_op, /* 9 */
293 * Don't use for system provided sysrqs, it is handled specially on
294 * sparc and will never arrive
297 &sysrq_reboot_op, /* b */
298 &sysrq_crashdump_op, /* c */
299 &sysrq_showlocks_op, /* d */
300 &sysrq_term_op, /* e */
301 &sysrq_moom_op, /* f */
304 &sysrq_kill_op, /* i */
306 &sysrq_SAK_op, /* k */
308 &sysrq_showmem_op, /* m */
309 &sysrq_unrt_op, /* n */
310 /* This will often be registered as 'Off' at init time */
312 &sysrq_showregs_op, /* p */
314 &sysrq_unraw_op, /* r */
315 &sysrq_sync_op, /* s */
316 &sysrq_showstate_op, /* t */
317 &sysrq_mountro_op, /* u */
318 /* May be assigned at init time by SMP VOYAGER */
326 /* key2index calculation, -1 on invalid index */
327 static int sysrq_key_table_key2index(int key)
331 if ((key >= '0') && (key <= '9'))
333 else if ((key >= 'a') && (key <= 'z'))
334 retval = key + 10 - 'a';
341 * get and put functions for the table, exposed to modules.
343 struct sysrq_key_op *__sysrq_get_key_op(int key)
345 struct sysrq_key_op *op_p = NULL;
348 i = sysrq_key_table_key2index(key);
350 op_p = sysrq_key_table[i];
354 static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
356 int i = sysrq_key_table_key2index(key);
359 sysrq_key_table[i] = op_p;
363 * This is the non-locking version of handle_sysrq. It must/can only be called
364 * by sysrq key handlers, as they are inside of the lock
366 void __handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty,
369 struct sysrq_key_op *op_p;
374 spin_lock_irqsave(&sysrq_key_table_lock, flags);
375 orig_log_level = console_loglevel;
376 console_loglevel = 7;
377 printk(KERN_INFO "SysRq : ");
379 op_p = __sysrq_get_key_op(key);
382 * Should we check for enabled operations (/proc/sysrq-trigger
383 * should not) and is the invoked operation enabled?
385 if (!check_mask || sysrq_enabled == 1 ||
386 (sysrq_enabled & op_p->enable_mask)) {
387 printk("%s\n", op_p->action_msg);
388 console_loglevel = orig_log_level;
389 op_p->handler(key, pt_regs, tty);
391 printk("This sysrq operation is disabled.\n");
395 /* Only print the help msg once per handler */
396 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
397 if (sysrq_key_table[i]) {
400 for (j = 0; sysrq_key_table[i] !=
401 sysrq_key_table[j]; j++)
405 printk("%s ", sysrq_key_table[i]->help_msg);
409 console_loglevel = orig_log_level;
411 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
415 * This function is called by the keyboard handler when SysRq is pressed
416 * and any other keycode arrives.
418 void handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty)
422 __handle_sysrq(key, pt_regs, tty, 1);
424 EXPORT_SYMBOL(handle_sysrq);
426 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
427 struct sysrq_key_op *remove_op_p)
433 spin_lock_irqsave(&sysrq_key_table_lock, flags);
434 if (__sysrq_get_key_op(key) == remove_op_p) {
435 __sysrq_put_key_op(key, insert_op_p);
440 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
444 int register_sysrq_key(int key, struct sysrq_key_op *op_p)
446 return __sysrq_swap_key_ops(key, op_p, NULL);
448 EXPORT_SYMBOL(register_sysrq_key);
450 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
452 return __sysrq_swap_key_ops(key, NULL, op_p);
454 EXPORT_SYMBOL(unregister_sysrq_key);