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 #include <linux/kexec.h>
  39
  40 #include <asm/ptrace.h>
  41
  42 /* Whether we react on sysrq keys or just ignore them */
  43 int sysrq_enabled = 1;
  44
  45 /* Loglevel sysrq handler */
  46 static 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 }
  55 static 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
  65 static 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 }
  72 static 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 */
  82 static 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 }
  90 static 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
  98 #ifdef CONFIG_KEXEC
  99 /* crashdump sysrq handler */
 100 static void sysrq_handle_crashdump(int key, struct pt_regs *pt_regs,
 101                                 struct tty_struct *tty)
 102 {
 103         crash_kexec(pt_regs);
 104 }
 105 static 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
 113 /* reboot sysrq handler */
 114 static void sysrq_handle_reboot(int key, struct pt_regs *pt_regs,
 115                                 struct tty_struct *tty)
 116 {
 117         local_irq_enable();
 118         emergency_restart();
 119 }
 120
 121 static 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
 128 static void sysrq_handle_sync(int key, struct pt_regs *pt_regs,
 129                               struct tty_struct *tty)
 130 {
 131         emergency_sync();
 132 }
 133
 134 static 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
 141 static void sysrq_handle_mountro(int key, struct pt_regs *pt_regs,
 142                                  struct tty_struct *tty)
 143 {
 144         emergency_remount();
 145 }
 146
 147 static 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 #ifdef CONFIG_DEBUG_MUTEXES
 157
 158 static void
 159 sysrq_handle_showlocks(int key, struct pt_regs *pt_regs, struct tty_struct *tty)
 160 {
 161         mutex_debug_show_all_locks();
 162 }
 163
 164 static struct sysrq_key_op sysrq_showlocks_op = {
 165         .handler        = sysrq_handle_showlocks,
 166         .help_msg       = "show-all-locks(D)",
 167         .action_msg     = "Show Locks Held",
 168 };
 169
 170 #endif
 171
 172 /* SHOW SYSRQ HANDLERS BLOCK */
 173
 174 static void sysrq_handle_showregs(int key, struct pt_regs *pt_regs,
 175                                   struct tty_struct *tty)
 176 {
 177         if (pt_regs)
 178                 show_regs(pt_regs);
 179 }
 180 static struct sysrq_key_op sysrq_showregs_op = {
 181         .handler        = sysrq_handle_showregs,
 182         .help_msg       = "showPc",
 183         .action_msg     = "Show Regs",
 184         .enable_mask    = SYSRQ_ENABLE_DUMP,
 185 };
 186
 187
 188 static void sysrq_handle_showstate(int key, struct pt_regs *pt_regs,
 189                                    struct tty_struct *tty)
 190 {
 191         show_state();
 192 }
 193 static struct sysrq_key_op sysrq_showstate_op = {
 194         .handler        = sysrq_handle_showstate,
 195         .help_msg       = "showTasks",
 196         .action_msg     = "Show State",
 197         .enable_mask    = SYSRQ_ENABLE_DUMP,
 198 };
 199
 200
 201 static void sysrq_handle_showmem(int key, struct pt_regs *pt_regs,
 202                                  struct tty_struct *tty)
 203 {
 204         show_mem();
 205 }
 206 static struct sysrq_key_op sysrq_showmem_op = {
 207         .handler        = sysrq_handle_showmem,
 208         .help_msg       = "showMem",
 209         .action_msg     = "Show Memory",
 210         .enable_mask    = SYSRQ_ENABLE_DUMP,
 211 };
 212
 213 /* SHOW SYSRQ HANDLERS BLOCK */
 214
 215
 216 /* SIGNAL SYSRQ HANDLERS BLOCK */
 217
 218 /* signal sysrq helper function
 219  * Sends a signal to all user processes */
 220 static void send_sig_all(int sig)
 221 {
 222         struct task_struct *p;
 223
 224         for_each_process(p) {
 225                 if (p->mm && p->pid != 1)
 226                         /* Not swapper, init nor kernel thread */
 227                         force_sig(sig, p);
 228         }
 229 }
 230
 231 static void sysrq_handle_term(int key, struct pt_regs *pt_regs,
 232                               struct tty_struct *tty)
 233 {
 234         send_sig_all(SIGTERM);
 235         console_loglevel = 8;
 236 }
 237 static struct sysrq_key_op sysrq_term_op = {
 238         .handler        = sysrq_handle_term,
 239         .help_msg       = "tErm",
 240         .action_msg     = "Terminate All Tasks",
 241         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
 242 };
 243
 244 static void moom_callback(void *ignored)
 245 {
 246         out_of_memory(&NODE_DATA(0)->node_zonelists[ZONE_NORMAL], GFP_KERNEL, 0);
 247 }
 248
 249 static DECLARE_WORK(moom_work, moom_callback, NULL);
 250
 251 static void sysrq_handle_moom(int key, struct pt_regs *pt_regs,
 252                               struct tty_struct *tty)
 253 {
 254         schedule_work(&moom_work);
 255 }
 256 static struct sysrq_key_op sysrq_moom_op = {
 257         .handler        = sysrq_handle_moom,
 258         .help_msg       = "Full",
 259         .action_msg     = "Manual OOM execution",
 260 };
 261
 262 static void sysrq_handle_kill(int key, struct pt_regs *pt_regs,
 263                               struct tty_struct *tty)
 264 {
 265         send_sig_all(SIGKILL);
 266         console_loglevel = 8;
 267 }
 268 static struct sysrq_key_op sysrq_kill_op = {
 269         .handler        = sysrq_handle_kill,
 270         .help_msg       = "kIll",
 271         .action_msg     = "Kill All Tasks",
 272         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
 273 };
 274
 275 /* END SIGNAL SYSRQ HANDLERS BLOCK */
 276
 277 static void sysrq_handle_unrt(int key, struct pt_regs *pt_regs,
 278                                 struct tty_struct *tty)
 279 {
 280         normalize_rt_tasks();
 281 }
 282 static struct sysrq_key_op sysrq_unrt_op = {
 283         .handler        = sysrq_handle_unrt,
 284         .help_msg       = "Nice",
 285         .action_msg     = "Nice All RT Tasks",
 286         .enable_mask    = SYSRQ_ENABLE_RTNICE,
 287 };
 288
 289 /* Key Operations table and lock */
 290 static DEFINE_SPINLOCK(sysrq_key_table_lock);
 291 #define SYSRQ_KEY_TABLE_LENGTH 36
 292 static struct sysrq_key_op *sysrq_key_table[SYSRQ_KEY_TABLE_LENGTH] = {
 293 /* 0 */ &sysrq_loglevel_op,
 294 /* 1 */ &sysrq_loglevel_op,
 295 /* 2 */ &sysrq_loglevel_op,
 296 /* 3 */ &sysrq_loglevel_op,
 297 /* 4 */ &sysrq_loglevel_op,
 298 /* 5 */ &sysrq_loglevel_op,
 299 /* 6 */ &sysrq_loglevel_op,
 300 /* 7 */ &sysrq_loglevel_op,
 301 /* 8 */ &sysrq_loglevel_op,
 302 /* 9 */ &sysrq_loglevel_op,
 303 /* a */ NULL, /* Don't use for system provided sysrqs,
 304                  it is handled specially on the sparc
 305                  and will never arrive */
 306 /* b */ &sysrq_reboot_op,
 307 #ifdef CONFIG_KEXEC
 308 /* c */ &sysrq_crashdump_op,
 309 #else
 310 /* c */ NULL,
 311 #endif
 312 #ifdef CONFIG_DEBUG_MUTEXES
 313 /* d */ &sysrq_showlocks_op,
 314 #else
 315 /* d */ NULL,
 316 #endif
 317 /* e */ &sysrq_term_op,
 318 /* f */ &sysrq_moom_op,
 319 /* g */ NULL,
 320 /* h */ NULL,
 321 /* i */ &sysrq_kill_op,
 322 /* j */ NULL,
 323 #ifdef CONFIG_VT
 324 /* k */ &sysrq_SAK_op,
 325 #else
 326 /* k */ NULL,
 327 #endif
 328 /* l */ NULL,
 329 /* m */ &sysrq_showmem_op,
 330 /* n */ &sysrq_unrt_op,
 331 /* o */ NULL, /* This will often be registered
 332                  as 'Off' at init time */
 333 /* p */ &sysrq_showregs_op,
 334 /* q */ NULL,
 335 #ifdef CONFIG_VT
 336 /* r */ &sysrq_unraw_op,
 337 #else
 338 /* r */ NULL,
 339 #endif
 340 /* s */ &sysrq_sync_op,
 341 /* t */ &sysrq_showstate_op,
 342 /* u */ &sysrq_mountro_op,
 343 /* v */ NULL, /* May be assigned at init time by SMP VOYAGER */
 344 /* w */ NULL,
 345 /* x */ NULL,
 346 /* y */ NULL,
 347 /* z */ NULL
 348 };
 349
 350 /* key2index calculation, -1 on invalid index */
 351 static int sysrq_key_table_key2index(int key) {
 352         int retval;
 353         if ((key >= '0') && (key <= '9')) {
 354                 retval = key - '0';
 355         } else if ((key >= 'a') && (key <= 'z')) {
 356                 retval = key + 10 - 'a';
 357         } else {
 358                 retval = -1;
 359         }
 360         return retval;
 361 }
 362
 363 /*
 364  * get and put functions for the table, exposed to modules.
 365  */
 366
 367 struct sysrq_key_op *__sysrq_get_key_op (int key) {
 368         struct sysrq_key_op *op_p;
 369         int i;
 370
 371         i = sysrq_key_table_key2index(key);
 372         op_p = (i == -1) ? NULL : sysrq_key_table[i];
 373         return op_p;
 374 }
 375
 376 static void __sysrq_put_key_op (int key, struct sysrq_key_op *op_p) {
 377         int i;
 378
 379         i = sysrq_key_table_key2index(key);
 380         if (i != -1)
 381                 sysrq_key_table[i] = op_p;
 382 }
 383
 384 /*
 385  * This is the non-locking version of handle_sysrq
 386  * It must/can only be called by sysrq key handlers,
 387  * as they are inside of the lock
 388  */
 389
 390 void __handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty, int check_mask)
 391 {
 392         struct sysrq_key_op *op_p;
 393         int orig_log_level;
 394         int i, j;
 395         unsigned long flags;
 396
 397         spin_lock_irqsave(&sysrq_key_table_lock, flags);
 398         orig_log_level = console_loglevel;
 399         console_loglevel = 7;
 400         printk(KERN_INFO "SysRq : ");
 401
 402         op_p = __sysrq_get_key_op(key);
 403         if (op_p) {
 404                 /* Should we check for enabled operations (/proc/sysrq-trigger should not)
 405                  * and is the invoked operation enabled? */
 406                 if (!check_mask || sysrq_enabled == 1 ||
 407                     (sysrq_enabled & op_p->enable_mask)) {
 408                         printk ("%s\n", op_p->action_msg);
 409                         console_loglevel = orig_log_level;
 410                         op_p->handler(key, pt_regs, tty);
 411                 }
 412                 else
 413                         printk("This sysrq operation is disabled.\n");
 414         } else {
 415                 printk("HELP : ");
 416                 /* Only print the help msg once per handler */
 417                 for (i=0; i<SYSRQ_KEY_TABLE_LENGTH; i++)
 418                 if (sysrq_key_table[i]) {
 419                         for (j=0; sysrq_key_table[i] != sysrq_key_table[j]; j++);
 420                         if (j == i)
 421                                 printk ("%s ", sysrq_key_table[i]->help_msg);
 422                 }
 423                 printk ("\n");
 424                 console_loglevel = orig_log_level;
 425         }
 426         spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
 427 }
 428
 429 /*
 430  * This function is called by the keyboard handler when SysRq is pressed
 431  * and any other keycode arrives.
 432  */
 433
 434 void handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty)
 435 {
 436         if (!sysrq_enabled)
 437                 return;
 438         __handle_sysrq(key, pt_regs, tty, 1);
 439 }
 440
 441 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
 442                                 struct sysrq_key_op *remove_op_p) {
 443
 444         int retval;
 445         unsigned long flags;
 446
 447         spin_lock_irqsave(&sysrq_key_table_lock, flags);
 448         if (__sysrq_get_key_op(key) == remove_op_p) {
 449                 __sysrq_put_key_op(key, insert_op_p);
 450                 retval = 0;
 451         } else {
 452                 retval = -1;
 453         }
 454         spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
 455
 456         return retval;
 457 }
 458
 459 int register_sysrq_key(int key, struct sysrq_key_op *op_p)
 460 {
 461         return __sysrq_swap_key_ops(key, op_p, NULL);
 462 }
 463
 464 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
 465 {
 466         return __sysrq_swap_key_ops(key, NULL, op_p);
 467 }
 468
 469 EXPORT_SYMBOL(handle_sysrq);
 470 EXPORT_SYMBOL(register_sysrq_key);
 471 EXPORT_SYMBOL(unregister_sysrq_key);