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/kernel.h>
  28 #include <linux/module.h>
  29 #include <linux/suspend.h>
  30 #include <linux/writeback.h>
  31 #include <linux/buffer_head.h>          /* for fsync_bdev() */
  32 #include <linux/swap.h>
  33 #include <linux/spinlock.h>
  34 #include <linux/vt_kern.h>
  35 #include <linux/workqueue.h>
  36 #include <linux/kexec.h>
  37 #include <linux/irq.h>
  38 #include <linux/hrtimer.h>
  39 #include <linux/oom.h>
  40
  41 #include <asm/ptrace.h>
  42 #include <asm/irq_regs.h>
  43
  44 /* Whether we react on sysrq keys or just ignore them */
  45 int __read_mostly __sysrq_enabled = 1;
  46
  47 static int __read_mostly sysrq_always_enabled;
  48
  49 int sysrq_on(void)
  50 {
  51         return __sysrq_enabled || sysrq_always_enabled;
  52 }
  53
  54 /*
  55  * A value of 1 means 'all', other nonzero values are an op mask:
  56  */
  57 static inline int sysrq_on_mask(int mask)
  58 {
  59         return sysrq_always_enabled || __sysrq_enabled == 1 ||
  60                                                 (__sysrq_enabled & mask);
  61 }
  62
  63 static int __init sysrq_always_enabled_setup(char *str)
  64 {
  65         sysrq_always_enabled = 1;
  66         printk(KERN_INFO "debug: sysrq always enabled.\n");
  67
  68         return 1;
  69 }
  70
  71 __setup("sysrq_always_enabled", sysrq_always_enabled_setup);
  72
  73
  74 static void sysrq_handle_loglevel(int key, struct tty_struct *tty)
  75 {
  76         int i;
  77         i = key - '0';
  78         console_loglevel = 7;
  79         printk("Loglevel set to %d\n", i);
  80         console_loglevel = i;
  81 }
  82 static struct sysrq_key_op sysrq_loglevel_op = {
  83         .handler        = sysrq_handle_loglevel,
  84         .help_msg       = "loglevel0-8",
  85         .action_msg     = "Changing Loglevel",
  86         .enable_mask    = SYSRQ_ENABLE_LOG,
  87 };
  88
  89 #ifdef CONFIG_VT
  90 static void sysrq_handle_SAK(int key, struct tty_struct *tty)
  91 {
  92         struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
  93         schedule_work(SAK_work);
  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_show_timers(int key, struct tty_struct *tty)
 163 {
 164         sysrq_timer_list_show();
 165 }
 166
 167 static struct sysrq_key_op sysrq_show_timers_op = {
 168         .handler        = sysrq_handle_show_timers,
 169         .help_msg       = "show-all-timers(Q)",
 170         .action_msg     = "Show Pending Timers",
 171 };
 172
 173 static void sysrq_handle_mountro(int key, struct tty_struct *tty)
 174 {
 175         emergency_remount();
 176 }
 177 static struct sysrq_key_op sysrq_mountro_op = {
 178         .handler        = sysrq_handle_mountro,
 179         .help_msg       = "Unmount",
 180         .action_msg     = "Emergency Remount R/O",
 181         .enable_mask    = SYSRQ_ENABLE_REMOUNT,
 182 };
 183
 184 #ifdef CONFIG_LOCKDEP
 185 static void sysrq_handle_showlocks(int key, struct tty_struct *tty)
 186 {
 187         debug_show_all_locks();
 188 }
 189
 190 static struct sysrq_key_op sysrq_showlocks_op = {
 191         .handler        = sysrq_handle_showlocks,
 192         .help_msg       = "show-all-locks(D)",
 193         .action_msg     = "Show Locks Held",
 194 };
 195 #else
 196 #define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
 197 #endif
 198
 199 static void sysrq_handle_showregs(int key, struct tty_struct *tty)
 200 {
 201         struct pt_regs *regs = get_irq_regs();
 202         if (regs)
 203                 show_regs(regs);
 204 }
 205 static struct sysrq_key_op sysrq_showregs_op = {
 206         .handler        = sysrq_handle_showregs,
 207         .help_msg       = "showPc",
 208         .action_msg     = "Show Regs",
 209         .enable_mask    = SYSRQ_ENABLE_DUMP,
 210 };
 211
 212 static void sysrq_handle_showstate(int key, struct tty_struct *tty)
 213 {
 214         show_state();
 215 }
 216 static struct sysrq_key_op sysrq_showstate_op = {
 217         .handler        = sysrq_handle_showstate,
 218         .help_msg       = "showTasks",
 219         .action_msg     = "Show State",
 220         .enable_mask    = SYSRQ_ENABLE_DUMP,
 221 };
 222
 223 static void sysrq_handle_showstate_blocked(int key, struct tty_struct *tty)
 224 {
 225         show_state_filter(TASK_UNINTERRUPTIBLE);
 226 }
 227 static struct sysrq_key_op sysrq_showstate_blocked_op = {
 228         .handler        = sysrq_handle_showstate_blocked,
 229         .help_msg       = "shoW-blocked-tasks",
 230         .action_msg     = "Show Blocked State",
 231         .enable_mask    = SYSRQ_ENABLE_DUMP,
 232 };
 233
 234
 235 static void sysrq_handle_showmem(int key, struct tty_struct *tty)
 236 {
 237         show_mem();
 238 }
 239 static struct sysrq_key_op sysrq_showmem_op = {
 240         .handler        = sysrq_handle_showmem,
 241         .help_msg       = "showMem",
 242         .action_msg     = "Show Memory",
 243         .enable_mask    = SYSRQ_ENABLE_DUMP,
 244 };
 245
 246 /*
 247  * Signal sysrq helper function.  Sends a signal to all user processes.
 248  */
 249 static void send_sig_all(int sig)
 250 {
 251         struct task_struct *p;
 252
 253         for_each_process(p) {
 254                 if (p->mm && !is_init(p))
 255                         /* Not swapper, init nor kernel thread */
 256                         force_sig(sig, p);
 257         }
 258 }
 259
 260 static void sysrq_handle_term(int key, struct tty_struct *tty)
 261 {
 262         send_sig_all(SIGTERM);
 263         console_loglevel = 8;
 264 }
 265 static struct sysrq_key_op sysrq_term_op = {
 266         .handler        = sysrq_handle_term,
 267         .help_msg       = "tErm",
 268         .action_msg     = "Terminate All Tasks",
 269         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
 270 };
 271
 272 static void moom_callback(struct work_struct *ignored)
 273 {
 274         out_of_memory(&NODE_DATA(0)->node_zonelists[ZONE_NORMAL],
 275                         GFP_KERNEL, 0);
 276 }
 277
 278 static DECLARE_WORK(moom_work, moom_callback);
 279
 280 static void sysrq_handle_moom(int key, struct tty_struct *tty)
 281 {
 282         schedule_work(&moom_work);
 283 }
 284 static struct sysrq_key_op sysrq_moom_op = {
 285         .handler        = sysrq_handle_moom,
 286         .help_msg       = "Full",
 287         .action_msg     = "Manual OOM execution",
 288 };
 289
 290 static void sysrq_handle_kill(int key, struct tty_struct *tty)
 291 {
 292         send_sig_all(SIGKILL);
 293         console_loglevel = 8;
 294 }
 295 static struct sysrq_key_op sysrq_kill_op = {
 296         .handler        = sysrq_handle_kill,
 297         .help_msg       = "kIll",
 298         .action_msg     = "Kill All Tasks",
 299         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
 300 };
 301
 302 static void sysrq_handle_unrt(int key, struct tty_struct *tty)
 303 {
 304         normalize_rt_tasks();
 305 }
 306 static struct sysrq_key_op sysrq_unrt_op = {
 307         .handler        = sysrq_handle_unrt,
 308         .help_msg       = "Nice",
 309         .action_msg     = "Nice All RT Tasks",
 310         .enable_mask    = SYSRQ_ENABLE_RTNICE,
 311 };
 312
 313 /* Key Operations table and lock */
 314 static DEFINE_SPINLOCK(sysrq_key_table_lock);
 315
 316 static struct sysrq_key_op *sysrq_key_table[36] = {
 317         &sysrq_loglevel_op,             /* 0 */
 318         &sysrq_loglevel_op,             /* 1 */
 319         &sysrq_loglevel_op,             /* 2 */
 320         &sysrq_loglevel_op,             /* 3 */
 321         &sysrq_loglevel_op,             /* 4 */
 322         &sysrq_loglevel_op,             /* 5 */
 323         &sysrq_loglevel_op,             /* 6 */
 324         &sysrq_loglevel_op,             /* 7 */
 325         &sysrq_loglevel_op,             /* 8 */
 326         &sysrq_loglevel_op,             /* 9 */
 327
 328         /*
 329          * a: Don't use for system provided sysrqs, it is handled specially on
 330          * sparc and will never arrive.
 331          */
 332         NULL,                           /* a */
 333         &sysrq_reboot_op,               /* b */
 334         &sysrq_crashdump_op,            /* c & ibm_emac driver debug */
 335         &sysrq_showlocks_op,            /* d */
 336         &sysrq_term_op,                 /* e */
 337         &sysrq_moom_op,                 /* f */
 338         /* g: May be registered by ppc for kgdb */
 339         NULL,                           /* g */
 340         NULL,                           /* h */
 341         &sysrq_kill_op,                 /* i */
 342         NULL,                           /* j */
 343         &sysrq_SAK_op,                  /* k */
 344         NULL,                           /* l */
 345         &sysrq_showmem_op,              /* m */
 346         &sysrq_unrt_op,                 /* n */
 347         /* o: This will often be registered as 'Off' at init time */
 348         NULL,                           /* o */
 349         &sysrq_showregs_op,             /* p */
 350         &sysrq_show_timers_op,          /* q */
 351         &sysrq_unraw_op,                /* r */
 352         &sysrq_sync_op,                 /* s */
 353         &sysrq_showstate_op,            /* t */
 354         &sysrq_mountro_op,              /* u */
 355         /* v: May be registered at init time by SMP VOYAGER */
 356         NULL,                           /* v */
 357         &sysrq_showstate_blocked_op,    /* w */
 358         /* x: May be registered on ppc/powerpc for xmon */
 359         NULL,                           /* x */
 360         NULL,                           /* y */
 361         NULL                            /* z */
 362 };
 363
 364 /* key2index calculation, -1 on invalid index */
 365 static int sysrq_key_table_key2index(int key)
 366 {
 367         int retval;
 368
 369         if ((key >= '0') && (key <= '9'))
 370                 retval = key - '0';
 371         else if ((key >= 'a') && (key <= 'z'))
 372                 retval = key + 10 - 'a';
 373         else
 374                 retval = -1;
 375         return retval;
 376 }
 377
 378 /*
 379  * get and put functions for the table, exposed to modules.
 380  */
 381 struct sysrq_key_op *__sysrq_get_key_op(int key)
 382 {
 383         struct sysrq_key_op *op_p = NULL;
 384         int i;
 385
 386         i = sysrq_key_table_key2index(key);
 387         if (i != -1)
 388                 op_p = sysrq_key_table[i];
 389         return op_p;
 390 }
 391
 392 static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
 393 {
 394         int i = sysrq_key_table_key2index(key);
 395
 396         if (i != -1)
 397                 sysrq_key_table[i] = op_p;
 398 }
 399
 400 /*
 401  * This is the non-locking version of handle_sysrq.  It must/can only be called
 402  * by sysrq key handlers, as they are inside of the lock
 403  */
 404 void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
 405 {
 406         struct sysrq_key_op *op_p;
 407         int orig_log_level;
 408         int i;
 409         unsigned long flags;
 410
 411         spin_lock_irqsave(&sysrq_key_table_lock, flags);
 412         orig_log_level = console_loglevel;
 413         console_loglevel = 7;
 414         printk(KERN_INFO "SysRq : ");
 415
 416         op_p = __sysrq_get_key_op(key);
 417         if (op_p) {
 418                 /*
 419                  * Should we check for enabled operations (/proc/sysrq-trigger
 420                  * should not) and is the invoked operation enabled?
 421                  */
 422                 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
 423                         printk("%s\n", op_p->action_msg);
 424                         console_loglevel = orig_log_level;
 425                         op_p->handler(key, tty);
 426                 } else {
 427                         printk("This sysrq operation is disabled.\n");
 428                 }
 429         } else {
 430                 printk("HELP : ");
 431                 /* Only print the help msg once per handler */
 432                 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
 433                         if (sysrq_key_table[i]) {
 434                                 int j;
 435
 436                                 for (j = 0; sysrq_key_table[i] !=
 437                                                 sysrq_key_table[j]; j++)
 438                                         ;
 439                                 if (j != i)
 440                                         continue;
 441                                 printk("%s ", sysrq_key_table[i]->help_msg);
 442                         }
 443                 }
 444                 printk("\n");
 445                 console_loglevel = orig_log_level;
 446         }
 447         spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
 448 }
 449
 450 /*
 451  * This function is called by the keyboard handler when SysRq is pressed
 452  * and any other keycode arrives.
 453  */
 454 void handle_sysrq(int key, struct tty_struct *tty)
 455 {
 456         if (sysrq_on())
 457                 __handle_sysrq(key, tty, 1);
 458 }
 459 EXPORT_SYMBOL(handle_sysrq);
 460
 461 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
 462                                 struct sysrq_key_op *remove_op_p)
 463 {
 464
 465         int retval;
 466         unsigned long flags;
 467
 468         spin_lock_irqsave(&sysrq_key_table_lock, flags);
 469         if (__sysrq_get_key_op(key) == remove_op_p) {
 470                 __sysrq_put_key_op(key, insert_op_p);
 471                 retval = 0;
 472         } else {
 473                 retval = -1;
 474         }
 475         spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
 476         return retval;
 477 }
 478
 479 int register_sysrq_key(int key, struct sysrq_key_op *op_p)
 480 {
 481         return __sysrq_swap_key_ops(key, op_p, NULL);
 482 }
 483 EXPORT_SYMBOL(register_sysrq_key);
 484
 485 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
 486 {
 487         return __sysrq_swap_key_ops(key, NULL, op_p);
 488 }
 489 EXPORT_SYMBOL(unregister_sysrq_key);