drivers/char/sysrq.c

   1 /* -*- 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>
  38
  39 #include <asm/ptrace.h>
  40
  41 /* Whether we react on sysrq keys or just ignore them */
  42 int sysrq_enabled = 1;
  43
  44 /* Loglevel sysrq handler */
  45 static void sysrq_handle_loglevel(int key, struct pt_regs *pt_regs,
  46                                   struct tty_struct *tty)
  47 {
  48         int i;
  49         i = key - '0';
  50         console_loglevel = 7;
  51         printk("Loglevel set to %d\n", i);
  52         console_loglevel = i;
  53 }
  54 static struct sysrq_key_op sysrq_loglevel_op = {
  55         .handler        = sysrq_handle_loglevel,
  56         .help_msg       = "loglevel0-8",
  57         .action_msg     = "Changing Loglevel",
  58         .enable_mask    = SYSRQ_ENABLE_LOG,
  59 };
  60
  61
  62 /* SAK sysrq handler */
  63 #ifdef CONFIG_VT
  64 static void sysrq_handle_SAK(int key, struct pt_regs *pt_regs,
  65                              struct tty_struct *tty)
  66 {
  67         if (tty)
  68                 do_SAK(tty);
  69         reset_vc(vc_cons[fg_console].d);
  70 }
  71 static struct sysrq_key_op sysrq_SAK_op = {
  72         .handler        = sysrq_handle_SAK,
  73         .help_msg       = "saK",
  74         .action_msg     = "SAK",
  75         .enable_mask    = SYSRQ_ENABLE_KEYBOARD,
  76 };
  77 #endif
  78
  79 #ifdef CONFIG_VT
  80 /* unraw sysrq handler */
  81 static void sysrq_handle_unraw(int key, struct pt_regs *pt_regs,
  82                                struct tty_struct *tty)
  83 {
  84         struct kbd_struct *kbd = &kbd_table[fg_console];
  85
  86         if (kbd)
  87                 kbd->kbdmode = VC_XLATE;
  88 }
  89 static struct sysrq_key_op sysrq_unraw_op = {
  90         .handler        = sysrq_handle_unraw,
  91         .help_msg       = "unRaw",
  92         .action_msg     = "Keyboard mode set to XLATE",
  93         .enable_mask    = SYSRQ_ENABLE_KEYBOARD,
  94 };
  95 #endif /* CONFIG_VT */
  96
  97 /* reboot sysrq handler */
  98 static void sysrq_handle_reboot(int key, struct pt_regs *pt_regs,
  99                                 struct tty_struct *tty)
 100 {
 101         local_irq_enable();
 102         machine_restart(NULL);
 103 }
 104
 105 static struct sysrq_key_op sysrq_reboot_op = {
 106         .handler        = sysrq_handle_reboot,
 107         .help_msg       = "reBoot",
 108         .action_msg     = "Resetting",
 109         .enable_mask    = SYSRQ_ENABLE_BOOT,
 110 };
 111
 112 static void sysrq_handle_sync(int key, struct pt_regs *pt_regs,
 113                               struct tty_struct *tty)
 114 {
 115         emergency_sync();
 116 }
 117
 118 static struct sysrq_key_op sysrq_sync_op = {
 119         .handler        = sysrq_handle_sync,
 120         .help_msg       = "Sync",
 121         .action_msg     = "Emergency Sync",
 122         .enable_mask    = SYSRQ_ENABLE_SYNC,
 123 };
 124
 125 static void sysrq_handle_mountro(int key, struct pt_regs *pt_regs,
 126                                  struct tty_struct *tty)
 127 {
 128         emergency_remount();
 129 }
 130
 131 static struct sysrq_key_op sysrq_mountro_op = {
 132         .handler        = sysrq_handle_mountro,
 133         .help_msg       = "Unmount",
 134         .action_msg     = "Emergency Remount R/O",
 135         .enable_mask    = SYSRQ_ENABLE_REMOUNT,
 136 };
 137
 138 /* END SYNC SYSRQ HANDLERS BLOCK */
 139
 140
 141 /* SHOW SYSRQ HANDLERS BLOCK */
 142
 143 static void sysrq_handle_showregs(int key, struct pt_regs *pt_regs,
 144                                   struct tty_struct *tty)
 145 {
 146         if (pt_regs)
 147                 show_regs(pt_regs);
 148 }
 149 static struct sysrq_key_op sysrq_showregs_op = {
 150         .handler        = sysrq_handle_showregs,
 151         .help_msg       = "showPc",
 152         .action_msg     = "Show Regs",
 153         .enable_mask    = SYSRQ_ENABLE_DUMP,
 154 };
 155
 156
 157 static void sysrq_handle_showstate(int key, struct pt_regs *pt_regs,
 158                                    struct tty_struct *tty)
 159 {
 160         show_state();
 161 }
 162 static struct sysrq_key_op sysrq_showstate_op = {
 163         .handler        = sysrq_handle_showstate,
 164         .help_msg       = "showTasks",
 165         .action_msg     = "Show State",
 166         .enable_mask    = SYSRQ_ENABLE_DUMP,
 167 };
 168
 169
 170 static void sysrq_handle_showmem(int key, struct pt_regs *pt_regs,
 171                                  struct tty_struct *tty)
 172 {
 173         show_mem();
 174 }
 175 static struct sysrq_key_op sysrq_showmem_op = {
 176         .handler        = sysrq_handle_showmem,
 177         .help_msg       = "showMem",
 178         .action_msg     = "Show Memory",
 179         .enable_mask    = SYSRQ_ENABLE_DUMP,
 180 };
 181
 182 /* SHOW SYSRQ HANDLERS BLOCK */
 183
 184
 185 /* SIGNAL SYSRQ HANDLERS BLOCK */
 186
 187 /* signal sysrq helper function
 188  * Sends a signal to all user processes */
 189 static void send_sig_all(int sig)
 190 {
 191         struct task_struct *p;
 192
 193         for_each_process(p) {
 194                 if (p->mm && p->pid != 1)
 195                         /* Not swapper, init nor kernel thread */
 196                         force_sig(sig, p);
 197         }
 198 }
 199
 200 static void sysrq_handle_term(int key, struct pt_regs *pt_regs,
 201                               struct tty_struct *tty)
 202 {
 203         send_sig_all(SIGTERM);
 204         console_loglevel = 8;
 205 }
 206 static struct sysrq_key_op sysrq_term_op = {
 207         .handler        = sysrq_handle_term,
 208         .help_msg       = "tErm",
 209         .action_msg     = "Terminate All Tasks",
 210         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
 211 };
 212
 213 static void moom_callback(void *ignored)
 214 {
 215         out_of_memory(GFP_KERNEL);
 216 }
 217
 218 static DECLARE_WORK(moom_work, moom_callback, NULL);
 219
 220 static void sysrq_handle_moom(int key, struct pt_regs *pt_regs,
 221                               struct tty_struct *tty)
 222 {
 223         schedule_work(&moom_work);
 224 }
 225 static struct sysrq_key_op sysrq_moom_op = {
 226         .handler        = sysrq_handle_moom,
 227         .help_msg       = "Full",
 228         .action_msg     = "Manual OOM execution",
 229 };
 230
 231 static void sysrq_handle_kill(int key, struct pt_regs *pt_regs,
 232                               struct tty_struct *tty)
 233 {
 234         send_sig_all(SIGKILL);
 235         console_loglevel = 8;
 236 }
 237 static struct sysrq_key_op sysrq_kill_op = {
 238         .handler        = sysrq_handle_kill,
 239         .help_msg       = "kIll",
 240         .action_msg     = "Kill All Tasks",
 241         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
 242 };
 243
 244 /* END SIGNAL SYSRQ HANDLERS BLOCK */
 245
 246 static void sysrq_handle_unrt(int key, struct pt_regs *pt_regs,
 247                                 struct tty_struct *tty)
 248 {
 249         normalize_rt_tasks();
 250 }
 251 static struct sysrq_key_op sysrq_unrt_op = {
 252         .handler        = sysrq_handle_unrt,
 253         .help_msg       = "Nice",
 254         .action_msg     = "Nice All RT Tasks",
 255         .enable_mask    = SYSRQ_ENABLE_RTNICE,
 256 };
 257
 258 /* Key Operations table and lock */
 259 static DEFINE_SPINLOCK(sysrq_key_table_lock);
 260 #define SYSRQ_KEY_TABLE_LENGTH 36
 261 static struct sysrq_key_op *sysrq_key_table[SYSRQ_KEY_TABLE_LENGTH] = {
 262 /* 0 */ &sysrq_loglevel_op,
 263 /* 1 */ &sysrq_loglevel_op,
 264 /* 2 */ &sysrq_loglevel_op,
 265 /* 3 */ &sysrq_loglevel_op,
 266 /* 4 */ &sysrq_loglevel_op,
 267 /* 5 */ &sysrq_loglevel_op,
 268 /* 6 */ &sysrq_loglevel_op,
 269 /* 7 */ &sysrq_loglevel_op,
 270 /* 8 */ &sysrq_loglevel_op,
 271 /* 9 */ &sysrq_loglevel_op,
 272 /* a */ NULL, /* Don't use for system provided sysrqs,
 273                  it is handled specially on the sparc
 274                  and will never arrive */
 275 /* b */ &sysrq_reboot_op,
 276 /* c */ NULL,
 277 /* d */ NULL,
 278 /* e */ &sysrq_term_op,
 279 /* f */ &sysrq_moom_op,
 280 /* g */ NULL,
 281 /* h */ NULL,
 282 /* i */ &sysrq_kill_op,
 283 /* j */ NULL,
 284 #ifdef CONFIG_VT
 285 /* k */ &sysrq_SAK_op,
 286 #else
 287 /* k */ NULL,
 288 #endif
 289 /* l */ NULL,
 290 /* m */ &sysrq_showmem_op,
 291 /* n */ &sysrq_unrt_op,
 292 /* o */ NULL, /* This will often be registered
 293                  as 'Off' at init time */
 294 /* p */ &sysrq_showregs_op,
 295 /* q */ NULL,
 296 #ifdef CONFIG_VT
 297 /* r */ &sysrq_unraw_op,
 298 #else
 299 /* r */ NULL,
 300 #endif
 301 /* s */ &sysrq_sync_op,
 302 /* t */ &sysrq_showstate_op,
 303 /* u */ &sysrq_mountro_op,
 304 /* v */ NULL, /* May be assigned at init time by SMP VOYAGER */
 305 /* w */ NULL,
 306 /* x */ NULL,
 307 /* y */ NULL,
 308 /* z */ NULL
 309 };
 310
 311 /* key2index calculation, -1 on invalid index */
 312 static int sysrq_key_table_key2index(int key) {
 313         int retval;
 314         if ((key >= '0') && (key <= '9')) {
 315                 retval = key - '0';
 316         } else if ((key >= 'a') && (key <= 'z')) {
 317                 retval = key + 10 - 'a';
 318         } else {
 319                 retval = -1;
 320         }
 321         return retval;
 322 }
 323
 324 /*
 325  * get and put functions for the table, exposed to modules.
 326  */
 327
 328 struct sysrq_key_op *__sysrq_get_key_op (int key) {
 329         struct sysrq_key_op *op_p;
 330         int i;
 331
 332         i = sysrq_key_table_key2index(key);
 333         op_p = (i == -1) ? NULL : sysrq_key_table[i];
 334         return op_p;
 335 }
 336
 337 void __sysrq_put_key_op (int key, struct sysrq_key_op *op_p) {
 338         int i;
 339
 340         i = sysrq_key_table_key2index(key);
 341         if (i != -1)
 342                 sysrq_key_table[i] = op_p;
 343 }
 344
 345 /*
 346  * This is the non-locking version of handle_sysrq
 347  * It must/can only be called by sysrq key handlers,
 348  * as they are inside of the lock
 349  */
 350
 351 void __handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty, int check_mask)
 352 {
 353         struct sysrq_key_op *op_p;
 354         int orig_log_level;
 355         int i, j;
 356         unsigned long flags;
 357
 358         spin_lock_irqsave(&sysrq_key_table_lock, flags);
 359         orig_log_level = console_loglevel;
 360         console_loglevel = 7;
 361         printk(KERN_INFO "SysRq : ");
 362
 363         op_p = __sysrq_get_key_op(key);
 364         if (op_p) {
 365                 /* Should we check for enabled operations (/proc/sysrq-trigger should not)
 366                  * and is the invoked operation enabled? */
 367                 if (!check_mask || sysrq_enabled == 1 ||
 368                     (sysrq_enabled & op_p->enable_mask)) {
 369                         printk ("%s\n", op_p->action_msg);
 370                         console_loglevel = orig_log_level;
 371                         op_p->handler(key, pt_regs, tty);
 372                 }
 373                 else
 374                         printk("This sysrq operation is disabled.\n");
 375         } else {
 376                 printk("HELP : ");
 377                 /* Only print the help msg once per handler */
 378                 for (i=0; i<SYSRQ_KEY_TABLE_LENGTH; i++)
 379                 if (sysrq_key_table[i]) {
 380                         for (j=0; sysrq_key_table[i] != sysrq_key_table[j]; j++);
 381                         if (j == i)
 382                                 printk ("%s ", sysrq_key_table[i]->help_msg);
 383                 }
 384                 printk ("\n");
 385                 console_loglevel = orig_log_level;
 386         }
 387         spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
 388 }
 389
 390 /*
 391  * This function is called by the keyboard handler when SysRq is pressed
 392  * and any other keycode arrives.
 393  */
 394
 395 void handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty)
 396 {
 397         if (!sysrq_enabled)
 398                 return;
 399         __handle_sysrq(key, pt_regs, tty, 1);
 400 }
 401
 402 int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
 403                                 struct sysrq_key_op *remove_op_p) {
 404
 405         int retval;
 406         unsigned long flags;
 407
 408         spin_lock_irqsave(&sysrq_key_table_lock, flags);
 409         if (__sysrq_get_key_op(key) == remove_op_p) {
 410                 __sysrq_put_key_op(key, insert_op_p);
 411                 retval = 0;
 412         } else {
 413                 retval = -1;
 414         }
 415         spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
 416
 417         return retval;
 418 }
 419
 420 int register_sysrq_key(int key, struct sysrq_key_op *op_p)
 421 {
 422         return __sysrq_swap_key_ops(key, op_p, NULL);
 423 }
 424
 425 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
 426 {
 427         return __sysrq_swap_key_ops(key, NULL, op_p);
 428 }
 429
 430 EXPORT_SYMBOL(handle_sysrq);
 431 EXPORT_SYMBOL(register_sysrq_key);
 432 EXPORT_SYMBOL(unregister_sysrq_key);