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/sched.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/mm.h>
  18 #include <linux/fs.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>
  38 #include <linux/irq.h>
  39
  40 #include <asm/ptrace.h>
  41 #include <asm/irq_regs.h>
  42
  43 /* Whether we react on sysrq keys or just ignore them */
  44 int __read_mostly __sysrq_enabled = 1;
  45
  46 static int __read_mostly sysrq_always_enabled;
  47
  48 int sysrq_on(void)
  49 {
  50         return __sysrq_enabled || sysrq_always_enabled;
  51 }
  52
  53 /*
  54  * A value of 1 means 'all', other nonzero values are an op mask:
  55  */
  56 static inline int sysrq_on_mask(int mask)
  57 {
  58         return sysrq_always_enabled || __sysrq_enabled == 1 ||
  59                                                 (__sysrq_enabled & mask);
  60 }
  61
  62 static int __init sysrq_always_enabled_setup(char *str)
  63 {
  64         sysrq_always_enabled = 1;
  65         printk(KERN_INFO "debug: sysrq always enabled.\n");
  66
  67         return 1;
  68 }
  69
  70 __setup("sysrq_always_enabled", sysrq_always_enabled_setup);
  71
  72
  73 static void sysrq_handle_loglevel(int key, struct tty_struct *tty)
  74 {
  75         int i;
  76         i = key - '0';
  77         console_loglevel = 7;
  78         printk("Loglevel set to %d\n", i);
  79         console_loglevel = i;
  80 }
  81 static struct sysrq_key_op sysrq_loglevel_op = {
  82         .handler        = sysrq_handle_loglevel,
  83         .help_msg       = "loglevel0-8",
  84         .action_msg     = "Changing Loglevel",
  85         .enable_mask    = SYSRQ_ENABLE_LOG,
  86 };
  87
  88 #ifdef CONFIG_VT
  89 static void sysrq_handle_SAK(int key, struct tty_struct *tty)
  90 {
  91         if (tty)
  92                 do_SAK(tty);
  93         reset_vc(vc_cons[fg_console].d);
  94 }
  95 static struct sysrq_key_op sysrq_SAK_op = {
  96         .handler        = sysrq_handle_SAK,
  97         .help_msg       = "saK",
  98         .action_msg     = "SAK",
  99         .enable_mask    = SYSRQ_ENABLE_KEYBOARD,
 100 };
 101 #else
 102 #define sysrq_SAK_op (*(struct sysrq_key_op *)0)
 103 #endif
 104
 105 #ifdef CONFIG_VT
 106 static void sysrq_handle_unraw(int key, struct tty_struct *tty)
 107 {
 108         struct kbd_struct *kbd = &kbd_table[fg_console];
 109
 110         if (kbd)
 111                 kbd->kbdmode = VC_XLATE;
 112 }
 113 static struct sysrq_key_op sysrq_unraw_op = {
 114         .handler        = sysrq_handle_unraw,
 115         .help_msg       = "unRaw",
 116         .action_msg     = "Keyboard mode set to XLATE",
 117         .enable_mask    = SYSRQ_ENABLE_KEYBOARD,
 118 };
 119 #else
 120 #define sysrq_unraw_op (*(struct sysrq_key_op *)0)
 121 #endif /* CONFIG_VT */
 122
 123 #ifdef CONFIG_KEXEC
 124 static void sysrq_handle_crashdump(int key, struct tty_struct *tty)
 125 {
 126         crash_kexec(get_irq_regs());
 127 }
 128 static struct sysrq_key_op sysrq_crashdump_op = {
 129         .handler        = sysrq_handle_crashdump,
 130         .help_msg       = "Crashdump",
 131         .action_msg     = "Trigger a crashdump",
 132         .enable_mask    = SYSRQ_ENABLE_DUMP,
 133 };
 134 #else
 135 #define sysrq_crashdump_op (*(struct sysrq_key_op *)0)
 136 #endif
 137
 138 static void sysrq_handle_reboot(int key, struct tty_struct *tty)
 139 {
 140         lockdep_off();
 141         local_irq_enable();
 142         emergency_restart();
 143 }
 144 static struct sysrq_key_op sysrq_reboot_op = {
 145         .handler        = sysrq_handle_reboot,
 146         .help_msg       = "reBoot",
 147         .action_msg     = "Resetting",
 148         .enable_mask    = SYSRQ_ENABLE_BOOT,
 149 };
 150
 151 static void sysrq_handle_sync(int key, struct tty_struct *tty)
 152 {
 153         emergency_sync();
 154 }
 155 static struct sysrq_key_op sysrq_sync_op = {
 156         .handler        = sysrq_handle_sync,
 157         .help_msg       = "Sync",
 158         .action_msg     = "Emergency Sync",
 159         .enable_mask    = SYSRQ_ENABLE_SYNC,
 160 };
 161
 162 static void sysrq_handle_mountro(int key, struct tty_struct *tty)
 163 {
 164         emergency_remount();
 165 }
 166 static struct sysrq_key_op sysrq_mountro_op = {
 167         .handler        = sysrq_handle_mountro,
 168         .help_msg       = "Unmount",
 169         .action_msg     = "Emergency Remount R/O",
 170         .enable_mask    = SYSRQ_ENABLE_REMOUNT,
 171 };
 172
 173 #ifdef CONFIG_LOCKDEP
 174 static void sysrq_handle_showlocks(int key, struct tty_struct *tty)
 175 {
 176         debug_show_all_locks();
 177 }
 178
 179 static struct sysrq_key_op sysrq_showlocks_op = {
 180         .handler        = sysrq_handle_showlocks,
 181         .help_msg       = "show-all-locks(D)",
 182         .action_msg     = "Show Locks Held",
 183 };
 184 #else
 185 #define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
 186 #endif
 187
 188 static void sysrq_handle_showregs(int key, struct tty_struct *tty)
 189 {
 190         struct pt_regs *regs = get_irq_regs();
 191         if (regs)
 192                 show_regs(regs);
 193 }
 194 static struct sysrq_key_op sysrq_showregs_op = {
 195         .handler        = sysrq_handle_showregs,
 196         .help_msg       = "showPc",
 197         .action_msg     = "Show Regs",
 198         .enable_mask    = SYSRQ_ENABLE_DUMP,
 199 };
 200
 201 static void sysrq_handle_showstate(int key, struct tty_struct *tty)
 202 {
 203         show_state();
 204 }
 205 static struct sysrq_key_op sysrq_showstate_op = {
 206         .handler        = sysrq_handle_showstate,
 207         .help_msg       = "showTasks",
 208         .action_msg     = "Show State",
 209         .enable_mask    = SYSRQ_ENABLE_DUMP,
 210 };
 211
 212 static void sysrq_handle_showstate_blocked(int key, struct tty_struct *tty)
 213 {
 214         show_state_filter(TASK_UNINTERRUPTIBLE);
 215 }
 216 static struct sysrq_key_op sysrq_showstate_blocked_op = {
 217         .handler        = sysrq_handle_showstate_blocked,
 218         .help_msg       = "showBlockedTasks",
 219         .action_msg     = "Show Blocked State",
 220         .enable_mask    = SYSRQ_ENABLE_DUMP,
 221 };
 222
 223
 224 static void sysrq_handle_showmem(int key, struct tty_struct *tty)
 225 {
 226         show_mem();
 227 }
 228 static struct sysrq_key_op sysrq_showmem_op = {
 229         .handler        = sysrq_handle_showmem,
 230         .help_msg       = "showMem",
 231         .action_msg     = "Show Memory",
 232         .enable_mask    = SYSRQ_ENABLE_DUMP,
 233 };
 234
 235 /*
 236  * Signal sysrq helper function.  Sends a signal to all user processes.
 237  */
 238 static void send_sig_all(int sig)
 239 {
 240         struct task_struct *p;
 241
 242         for_each_process(p) {
 243                 if (p->mm && !is_init(p))
 244                         /* Not swapper, init nor kernel thread */
 245                         force_sig(sig, p);
 246         }
 247 }
 248
 249 static void sysrq_handle_term(int key, struct tty_struct *tty)
 250 {
 251         send_sig_all(SIGTERM);
 252         console_loglevel = 8;
 253 }
 254 static struct sysrq_key_op sysrq_term_op = {
 255         .handler        = sysrq_handle_term,
 256         .help_msg       = "tErm",
 257         .action_msg     = "Terminate All Tasks",
 258         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
 259 };
 260
 261 static void moom_callback(struct work_struct *ignored)
 262 {
 263         out_of_memory(&NODE_DATA(0)->node_zonelists[ZONE_NORMAL],
 264                         GFP_KERNEL, 0);
 265 }
 266
 267 static DECLARE_WORK(moom_work, moom_callback);
 268
 269 static void sysrq_handle_moom(int key, struct tty_struct *tty)
 270 {
 271         schedule_work(&moom_work);
 272 }
 273 static struct sysrq_key_op sysrq_moom_op = {
 274         .handler        = sysrq_handle_moom,
 275         .help_msg       = "Full",
 276         .action_msg     = "Manual OOM execution",
 277 };
 278
 279 static void sysrq_handle_kill(int key, struct tty_struct *tty)
 280 {
 281         send_sig_all(SIGKILL);
 282         console_loglevel = 8;
 283 }
 284 static struct sysrq_key_op sysrq_kill_op = {
 285         .handler        = sysrq_handle_kill,
 286         .help_msg       = "kIll",
 287         .action_msg     = "Kill All Tasks",
 288         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
 289 };
 290
 291 static void sysrq_handle_unrt(int key, struct tty_struct *tty)
 292 {
 293         normalize_rt_tasks();
 294 }
 295 static struct sysrq_key_op sysrq_unrt_op = {
 296         .handler        = sysrq_handle_unrt,
 297         .help_msg       = "Nice",
 298         .action_msg     = "Nice All RT Tasks",
 299         .enable_mask    = SYSRQ_ENABLE_RTNICE,
 300 };
 301
 302 /* Key Operations table and lock */
 303 static DEFINE_SPINLOCK(sysrq_key_table_lock);
 304
 305 static struct sysrq_key_op *sysrq_key_table[36] = {
 306         &sysrq_loglevel_op,             /* 0 */
 307         &sysrq_loglevel_op,             /* 1 */
 308         &sysrq_loglevel_op,             /* 2 */
 309         &sysrq_loglevel_op,             /* 3 */
 310         &sysrq_loglevel_op,             /* 4 */
 311         &sysrq_loglevel_op,             /* 5 */
 312         &sysrq_loglevel_op,             /* 6 */
 313         &sysrq_loglevel_op,             /* 7 */
 314         &sysrq_loglevel_op,             /* 8 */
 315         &sysrq_loglevel_op,             /* 9 */
 316
 317         /*
 318          * Don't use for system provided sysrqs, it is handled specially on
 319          * sparc and will never arrive
 320          */
 321         NULL,                           /* a */
 322         &sysrq_reboot_op,               /* b */
 323         &sysrq_crashdump_op,            /* c */
 324         &sysrq_showlocks_op,            /* d */
 325         &sysrq_term_op,                 /* e */
 326         &sysrq_moom_op,                 /* f */
 327         NULL,                           /* g */
 328         NULL,                           /* h */
 329         &sysrq_kill_op,                 /* i */
 330         NULL,                           /* j */
 331         &sysrq_SAK_op,                  /* k */
 332         NULL,                           /* l */
 333         &sysrq_showmem_op,              /* m */
 334         &sysrq_unrt_op,                 /* n */
 335         /* This will often be registered as 'Off' at init time */
 336         NULL,                           /* o */
 337         &sysrq_showregs_op,             /* p */
 338         NULL,                           /* q */
 339         &sysrq_unraw_op,                        /* r */
 340         &sysrq_sync_op,                 /* s */
 341         &sysrq_showstate_op,            /* t */
 342         &sysrq_mountro_op,              /* u */
 343         /* May be assigned at init time by SMP VOYAGER */
 344         NULL,                           /* v */
 345         NULL,                           /* w */
 346         &sysrq_showstate_blocked_op,    /* x */
 347         NULL,                           /* y */
 348         NULL                            /* z */
 349 };
 350
 351 /* key2index calculation, -1 on invalid index */
 352 static int sysrq_key_table_key2index(int key)
 353 {
 354         int retval;
 355
 356         if ((key >= '0') && (key <= '9'))
 357                 retval = key - '0';
 358         else if ((key >= 'a') && (key <= 'z'))
 359                 retval = key + 10 - 'a';
 360         else
 361                 retval = -1;
 362         return retval;
 363 }
 364
 365 /*
 366  * get and put functions for the table, exposed to modules.
 367  */
 368 struct sysrq_key_op *__sysrq_get_key_op(int key)
 369 {
 370         struct sysrq_key_op *op_p = NULL;
 371         int i;
 372
 373         i = sysrq_key_table_key2index(key);
 374         if (i != -1)
 375                 op_p = sysrq_key_table[i];
 376         return op_p;
 377 }
 378
 379 static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
 380 {
 381         int i = sysrq_key_table_key2index(key);
 382
 383         if (i != -1)
 384                 sysrq_key_table[i] = op_p;
 385 }
 386
 387 /*
 388  * This is the non-locking version of handle_sysrq.  It must/can only be called
 389  * by sysrq key handlers, as they are inside of the lock
 390  */
 391 void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
 392 {
 393         struct sysrq_key_op *op_p;
 394         int orig_log_level;
 395         int i;
 396         unsigned long flags;
 397
 398         spin_lock_irqsave(&sysrq_key_table_lock, flags);
 399         orig_log_level = console_loglevel;
 400         console_loglevel = 7;
 401         printk(KERN_INFO "SysRq : ");
 402
 403         op_p = __sysrq_get_key_op(key);
 404         if (op_p) {
 405                 /*
 406                  * Should we check for enabled operations (/proc/sysrq-trigger
 407                  * should not) and is the invoked operation enabled?
 408                  */
 409                 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
 410                         printk("%s\n", op_p->action_msg);
 411                         console_loglevel = orig_log_level;
 412                         op_p->handler(key, tty);
 413                 } else {
 414                         printk("This sysrq operation is disabled.\n");
 415                 }
 416         } else {
 417                 printk("HELP : ");
 418                 /* Only print the help msg once per handler */
 419                 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
 420                         if (sysrq_key_table[i]) {
 421                                 int j;
 422
 423                                 for (j = 0; sysrq_key_table[i] !=
 424                                                 sysrq_key_table[j]; j++)
 425                                         ;
 426                                 if (j != i)
 427                                         continue;
 428                                 printk("%s ", sysrq_key_table[i]->help_msg);
 429                         }
 430                 }
 431                 printk("\n");
 432                 console_loglevel = orig_log_level;
 433         }
 434         spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
 435 }
 436
 437 /*
 438  * This function is called by the keyboard handler when SysRq is pressed
 439  * and any other keycode arrives.
 440  */
 441 void handle_sysrq(int key, struct tty_struct *tty)
 442 {
 443         if (sysrq_on())
 444                 __handle_sysrq(key, tty, 1);
 445 }
 446 EXPORT_SYMBOL(handle_sysrq);
 447
 448 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
 449                                 struct sysrq_key_op *remove_op_p)
 450 {
 451
 452         int retval;
 453         unsigned long flags;
 454
 455         spin_lock_irqsave(&sysrq_key_table_lock, flags);
 456         if (__sysrq_get_key_op(key) == remove_op_p) {
 457                 __sysrq_put_key_op(key, insert_op_p);
 458                 retval = 0;
 459         } else {
 460                 retval = -1;
 461         }
 462         spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
 463         return retval;
 464 }
 465
 466 int register_sysrq_key(int key, struct sysrq_key_op *op_p)
 467 {
 468         return __sysrq_swap_key_ops(key, op_p, NULL);
 469 }
 470 EXPORT_SYMBOL(register_sysrq_key);
 471
 472 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
 473 {
 474         return __sysrq_swap_key_ops(key, NULL, op_p);
 475 }
 476 EXPORT_SYMBOL(unregister_sysrq_key);