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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* -*- linux-c -*-
2 *
3 * $Id: sysrq.c,v 1.15 1998/08/23 14:56:41 mj Exp $
4 *
5 * Linux Magic System Request Key Hacks
6 *
7 * (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
8 * based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz>
9 *
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
13 */
14
15#include <linux/config.h>
16#include <linux/sched.h>
17#include <linux/interrupt.h>
18#include <linux/mm.h>
19#include <linux/fs.h>
20#include <linux/tty.h>
21#include <linux/mount.h>
22#include <linux/kdev_t.h>
23#include <linux/major.h>
24#include <linux/reboot.h>
25#include <linux/sysrq.h>
26#include <linux/kbd_kern.h>
27#include <linux/quotaops.h>
28#include <linux/smp_lock.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>
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -070038#include <linux/kexec.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070039
40#include <asm/ptrace.h>
41
42/* Whether we react on sysrq keys or just ignore them */
43int sysrq_enabled = 1;
44
45/* Loglevel sysrq handler */
46static void sysrq_handle_loglevel(int key, struct pt_regs *pt_regs,
47 struct tty_struct *tty)
48{
49 int i;
50 i = key - '0';
51 console_loglevel = 7;
52 printk("Loglevel set to %d\n", i);
53 console_loglevel = i;
54}
55static struct sysrq_key_op sysrq_loglevel_op = {
56 .handler = sysrq_handle_loglevel,
57 .help_msg = "loglevel0-8",
58 .action_msg = "Changing Loglevel",
59 .enable_mask = SYSRQ_ENABLE_LOG,
60};
61
62
63/* SAK sysrq handler */
64#ifdef CONFIG_VT
65static void sysrq_handle_SAK(int key, struct pt_regs *pt_regs,
66 struct tty_struct *tty)
67{
68 if (tty)
69 do_SAK(tty);
70 reset_vc(vc_cons[fg_console].d);
71}
72static struct sysrq_key_op sysrq_SAK_op = {
73 .handler = sysrq_handle_SAK,
74 .help_msg = "saK",
75 .action_msg = "SAK",
76 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
77};
78#endif
79
80#ifdef CONFIG_VT
81/* unraw sysrq handler */
82static void sysrq_handle_unraw(int key, struct pt_regs *pt_regs,
83 struct tty_struct *tty)
84{
85 struct kbd_struct *kbd = &kbd_table[fg_console];
86
87 if (kbd)
88 kbd->kbdmode = VC_XLATE;
89}
90static struct sysrq_key_op sysrq_unraw_op = {
91 .handler = sysrq_handle_unraw,
92 .help_msg = "unRaw",
93 .action_msg = "Keyboard mode set to XLATE",
94 .enable_mask = SYSRQ_ENABLE_KEYBOARD,
95};
96#endif /* CONFIG_VT */
97
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -070098#ifdef CONFIG_KEXEC
99/* crashdump sysrq handler */
100static void sysrq_handle_crashdump(int key, struct pt_regs *pt_regs,
101 struct tty_struct *tty)
102{
Alexander Nyberg6e274d12005-06-25 14:58:26 -0700103 crash_kexec(pt_regs);
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700104}
105static struct sysrq_key_op sysrq_crashdump_op = {
106 .handler = sysrq_handle_crashdump,
107 .help_msg = "Crashdump",
108 .action_msg = "Trigger a crashdump",
109 .enable_mask = SYSRQ_ENABLE_DUMP,
110};
111#endif
112
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113/* reboot sysrq handler */
114static void sysrq_handle_reboot(int key, struct pt_regs *pt_regs,
115 struct tty_struct *tty)
116{
117 local_irq_enable();
Eric W. Biederman4de8b9b2005-07-26 11:51:06 -0600118 emergency_restart();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119}
120
121static struct sysrq_key_op sysrq_reboot_op = {
122 .handler = sysrq_handle_reboot,
123 .help_msg = "reBoot",
124 .action_msg = "Resetting",
125 .enable_mask = SYSRQ_ENABLE_BOOT,
126};
127
128static void sysrq_handle_sync(int key, struct pt_regs *pt_regs,
129 struct tty_struct *tty)
130{
131 emergency_sync();
132}
133
134static struct sysrq_key_op sysrq_sync_op = {
135 .handler = sysrq_handle_sync,
136 .help_msg = "Sync",
137 .action_msg = "Emergency Sync",
138 .enable_mask = SYSRQ_ENABLE_SYNC,
139};
140
141static void sysrq_handle_mountro(int key, struct pt_regs *pt_regs,
142 struct tty_struct *tty)
143{
144 emergency_remount();
145}
146
147static struct sysrq_key_op sysrq_mountro_op = {
148 .handler = sysrq_handle_mountro,
149 .help_msg = "Unmount",
150 .action_msg = "Emergency Remount R/O",
151 .enable_mask = SYSRQ_ENABLE_REMOUNT,
152};
153
154/* END SYNC SYSRQ HANDLERS BLOCK */
155
156
157/* SHOW SYSRQ HANDLERS BLOCK */
158
159static void sysrq_handle_showregs(int key, struct pt_regs *pt_regs,
160 struct tty_struct *tty)
161{
162 if (pt_regs)
163 show_regs(pt_regs);
164}
165static struct sysrq_key_op sysrq_showregs_op = {
166 .handler = sysrq_handle_showregs,
167 .help_msg = "showPc",
168 .action_msg = "Show Regs",
169 .enable_mask = SYSRQ_ENABLE_DUMP,
170};
171
172
173static void sysrq_handle_showstate(int key, struct pt_regs *pt_regs,
174 struct tty_struct *tty)
175{
176 show_state();
177}
178static struct sysrq_key_op sysrq_showstate_op = {
179 .handler = sysrq_handle_showstate,
180 .help_msg = "showTasks",
181 .action_msg = "Show State",
182 .enable_mask = SYSRQ_ENABLE_DUMP,
183};
184
185
186static void sysrq_handle_showmem(int key, struct pt_regs *pt_regs,
187 struct tty_struct *tty)
188{
189 show_mem();
190}
191static struct sysrq_key_op sysrq_showmem_op = {
192 .handler = sysrq_handle_showmem,
193 .help_msg = "showMem",
194 .action_msg = "Show Memory",
195 .enable_mask = SYSRQ_ENABLE_DUMP,
196};
197
198/* SHOW SYSRQ HANDLERS BLOCK */
199
200
201/* SIGNAL SYSRQ HANDLERS BLOCK */
202
203/* signal sysrq helper function
204 * Sends a signal to all user processes */
205static void send_sig_all(int sig)
206{
207 struct task_struct *p;
208
209 for_each_process(p) {
210 if (p->mm && p->pid != 1)
211 /* Not swapper, init nor kernel thread */
212 force_sig(sig, p);
213 }
214}
215
216static void sysrq_handle_term(int key, struct pt_regs *pt_regs,
217 struct tty_struct *tty)
218{
219 send_sig_all(SIGTERM);
220 console_loglevel = 8;
221}
222static struct sysrq_key_op sysrq_term_op = {
223 .handler = sysrq_handle_term,
224 .help_msg = "tErm",
225 .action_msg = "Terminate All Tasks",
226 .enable_mask = SYSRQ_ENABLE_SIGNAL,
227};
228
229static void moom_callback(void *ignored)
230{
Marcelo Tosatti79b9ce32005-07-07 17:56:04 -0700231 out_of_memory(GFP_KERNEL, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232}
233
234static DECLARE_WORK(moom_work, moom_callback, NULL);
235
236static void sysrq_handle_moom(int key, struct pt_regs *pt_regs,
237 struct tty_struct *tty)
238{
239 schedule_work(&moom_work);
240}
241static struct sysrq_key_op sysrq_moom_op = {
242 .handler = sysrq_handle_moom,
243 .help_msg = "Full",
244 .action_msg = "Manual OOM execution",
245};
246
247static void sysrq_handle_kill(int key, struct pt_regs *pt_regs,
248 struct tty_struct *tty)
249{
250 send_sig_all(SIGKILL);
251 console_loglevel = 8;
252}
253static struct sysrq_key_op sysrq_kill_op = {
254 .handler = sysrq_handle_kill,
255 .help_msg = "kIll",
256 .action_msg = "Kill All Tasks",
257 .enable_mask = SYSRQ_ENABLE_SIGNAL,
258};
259
260/* END SIGNAL SYSRQ HANDLERS BLOCK */
261
262static void sysrq_handle_unrt(int key, struct pt_regs *pt_regs,
263 struct tty_struct *tty)
264{
265 normalize_rt_tasks();
266}
267static struct sysrq_key_op sysrq_unrt_op = {
268 .handler = sysrq_handle_unrt,
269 .help_msg = "Nice",
270 .action_msg = "Nice All RT Tasks",
271 .enable_mask = SYSRQ_ENABLE_RTNICE,
272};
273
274/* Key Operations table and lock */
275static DEFINE_SPINLOCK(sysrq_key_table_lock);
276#define SYSRQ_KEY_TABLE_LENGTH 36
277static struct sysrq_key_op *sysrq_key_table[SYSRQ_KEY_TABLE_LENGTH] = {
278/* 0 */ &sysrq_loglevel_op,
279/* 1 */ &sysrq_loglevel_op,
280/* 2 */ &sysrq_loglevel_op,
281/* 3 */ &sysrq_loglevel_op,
282/* 4 */ &sysrq_loglevel_op,
283/* 5 */ &sysrq_loglevel_op,
284/* 6 */ &sysrq_loglevel_op,
285/* 7 */ &sysrq_loglevel_op,
286/* 8 */ &sysrq_loglevel_op,
287/* 9 */ &sysrq_loglevel_op,
288/* a */ NULL, /* Don't use for system provided sysrqs,
289 it is handled specially on the sparc
290 and will never arrive */
291/* b */ &sysrq_reboot_op,
Hariprasad Nellitheertha86b1ae32005-06-25 14:58:25 -0700292#ifdef CONFIG_KEXEC
293/* c */ &sysrq_crashdump_op,
294#else
295/* c */ NULL,
296#endif
297/* d */ NULL,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298/* e */ &sysrq_term_op,
299/* f */ &sysrq_moom_op,
300/* g */ NULL,
301/* h */ NULL,
302/* i */ &sysrq_kill_op,
303/* j */ NULL,
304#ifdef CONFIG_VT
305/* k */ &sysrq_SAK_op,
306#else
307/* k */ NULL,
308#endif
309/* l */ NULL,
310/* m */ &sysrq_showmem_op,
311/* n */ &sysrq_unrt_op,
312/* o */ NULL, /* This will often be registered
313 as 'Off' at init time */
314/* p */ &sysrq_showregs_op,
315/* q */ NULL,
316#ifdef CONFIG_VT
317/* r */ &sysrq_unraw_op,
318#else
319/* r */ NULL,
320#endif
321/* s */ &sysrq_sync_op,
322/* t */ &sysrq_showstate_op,
323/* u */ &sysrq_mountro_op,
324/* v */ NULL, /* May be assigned at init time by SMP VOYAGER */
325/* w */ NULL,
326/* x */ NULL,
327/* y */ NULL,
328/* z */ NULL
329};
330
331/* key2index calculation, -1 on invalid index */
332static int sysrq_key_table_key2index(int key) {
333 int retval;
334 if ((key >= '0') && (key <= '9')) {
335 retval = key - '0';
336 } else if ((key >= 'a') && (key <= 'z')) {
337 retval = key + 10 - 'a';
338 } else {
339 retval = -1;
340 }
341 return retval;
342}
343
344/*
345 * get and put functions for the table, exposed to modules.
346 */
347
348struct sysrq_key_op *__sysrq_get_key_op (int key) {
349 struct sysrq_key_op *op_p;
350 int i;
351
352 i = sysrq_key_table_key2index(key);
353 op_p = (i == -1) ? NULL : sysrq_key_table[i];
354 return op_p;
355}
356
357void __sysrq_put_key_op (int key, struct sysrq_key_op *op_p) {
358 int i;
359
360 i = sysrq_key_table_key2index(key);
361 if (i != -1)
362 sysrq_key_table[i] = op_p;
363}
364
365/*
366 * This is the non-locking version of handle_sysrq
367 * It must/can only be called by sysrq key handlers,
368 * as they are inside of the lock
369 */
370
371void __handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty, int check_mask)
372{
373 struct sysrq_key_op *op_p;
374 int orig_log_level;
375 int i, j;
376 unsigned long flags;
377
378 spin_lock_irqsave(&sysrq_key_table_lock, flags);
379 orig_log_level = console_loglevel;
380 console_loglevel = 7;
381 printk(KERN_INFO "SysRq : ");
382
383 op_p = __sysrq_get_key_op(key);
384 if (op_p) {
385 /* Should we check for enabled operations (/proc/sysrq-trigger should not)
386 * and is the invoked operation enabled? */
387 if (!check_mask || sysrq_enabled == 1 ||
388 (sysrq_enabled & op_p->enable_mask)) {
389 printk ("%s\n", op_p->action_msg);
390 console_loglevel = orig_log_level;
391 op_p->handler(key, pt_regs, tty);
392 }
393 else
394 printk("This sysrq operation is disabled.\n");
395 } else {
396 printk("HELP : ");
397 /* Only print the help msg once per handler */
398 for (i=0; i<SYSRQ_KEY_TABLE_LENGTH; i++)
399 if (sysrq_key_table[i]) {
400 for (j=0; sysrq_key_table[i] != sysrq_key_table[j]; j++);
401 if (j == i)
402 printk ("%s ", sysrq_key_table[i]->help_msg);
403 }
404 printk ("\n");
405 console_loglevel = orig_log_level;
406 }
407 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
408}
409
410/*
411 * This function is called by the keyboard handler when SysRq is pressed
412 * and any other keycode arrives.
413 */
414
415void handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty)
416{
417 if (!sysrq_enabled)
418 return;
419 __handle_sysrq(key, pt_regs, tty, 1);
420}
421
422int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
423 struct sysrq_key_op *remove_op_p) {
424
425 int retval;
426 unsigned long flags;
427
428 spin_lock_irqsave(&sysrq_key_table_lock, flags);
429 if (__sysrq_get_key_op(key) == remove_op_p) {
430 __sysrq_put_key_op(key, insert_op_p);
431 retval = 0;
432 } else {
433 retval = -1;
434 }
435 spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
436
437 return retval;
438}
439
440int register_sysrq_key(int key, struct sysrq_key_op *op_p)
441{
442 return __sysrq_swap_key_ops(key, op_p, NULL);
443}
444
445int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
446{
447 return __sysrq_swap_key_ops(key, NULL, op_p);
448}
449
450EXPORT_SYMBOL(handle_sysrq);
451EXPORT_SYMBOL(register_sysrq_key);
452EXPORT_SYMBOL(unregister_sysrq_key);