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
  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         struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
  92         schedule_work(SAK_work);
  93 }
  94 static struct sysrq_key_op sysrq_SAK_op = {
  95         .handler        = sysrq_handle_SAK,
  96         .help_msg       = "saK",
  97         .action_msg     = "SAK",
  98         .enable_mask    = SYSRQ_ENABLE_KEYBOARD,
  99 };
 100 #else
 101 #define sysrq_SAK_op (*(struct sysrq_key_op *)0)
 102 #endif
 103
 104 #ifdef CONFIG_VT
 105 static void sysrq_handle_unraw(int key, struct tty_struct *tty)
 106 {
 107         struct kbd_struct *kbd = &kbd_table[fg_console];
 108
 109         if (kbd)
 110                 kbd->kbdmode = VC_XLATE;
 111 }
 112 static struct sysrq_key_op sysrq_unraw_op = {
 113         .handler        = sysrq_handle_unraw,
 114         .help_msg       = "unRaw",
 115         .action_msg     = "Keyboard mode set to XLATE",
 116         .enable_mask    = SYSRQ_ENABLE_KEYBOARD,
 117 };
 118 #else
 119 #define sysrq_unraw_op (*(struct sysrq_key_op *)0)
 120 #endif /* CONFIG_VT */
 121
 122 #ifdef CONFIG_KEXEC
 123 static void sysrq_handle_crashdump(int key, struct tty_struct *tty)
 124 {
 125         crash_kexec(get_irq_regs());
 126 }
 127 static struct sysrq_key_op sysrq_crashdump_op = {
 128         .handler        = sysrq_handle_crashdump,
 129         .help_msg       = "Crashdump",
 130         .action_msg     = "Trigger a crashdump",
 131         .enable_mask    = SYSRQ_ENABLE_DUMP,
 132 };
 133 #else
 134 #define sysrq_crashdump_op (*(struct sysrq_key_op *)0)
 135 #endif
 136
 137 static void sysrq_handle_reboot(int key, struct tty_struct *tty)
 138 {
 139         lockdep_off();
 140         local_irq_enable();
 141         emergency_restart();
 142 }
 143 static struct sysrq_key_op sysrq_reboot_op = {
 144         .handler        = sysrq_handle_reboot,
 145         .help_msg       = "reBoot",
 146         .action_msg     = "Resetting",
 147         .enable_mask    = SYSRQ_ENABLE_BOOT,
 148 };
 149
 150 static void sysrq_handle_sync(int key, struct tty_struct *tty)
 151 {
 152         emergency_sync();
 153 }
 154 static struct sysrq_key_op sysrq_sync_op = {
 155         .handler        = sysrq_handle_sync,
 156         .help_msg       = "Sync",
 157         .action_msg     = "Emergency Sync",
 158         .enable_mask    = SYSRQ_ENABLE_SYNC,
 159 };
 160
 161 static void sysrq_handle_show_timers(int key, struct tty_struct *tty)
 162 {
 163         sysrq_timer_list_show();
 164 }
 165
 166 static struct sysrq_key_op sysrq_show_timers_op = {
 167         .handler        = sysrq_handle_show_timers,
 168         .help_msg       = "show-all-timers(Q)",
 169         .action_msg     = "Show Pending Timers",
 170 };
 171
 172 static void sysrq_handle_mountro(int key, struct tty_struct *tty)
 173 {
 174         emergency_remount();
 175 }
 176 static struct sysrq_key_op sysrq_mountro_op = {
 177         .handler        = sysrq_handle_mountro,
 178         .help_msg       = "Unmount",
 179         .action_msg     = "Emergency Remount R/O",
 180         .enable_mask    = SYSRQ_ENABLE_REMOUNT,
 181 };
 182
 183 #ifdef CONFIG_LOCKDEP
 184 static void sysrq_handle_showlocks(int key, struct tty_struct *tty)
 185 {
 186         debug_show_all_locks();
 187 }
 188
 189 static struct sysrq_key_op sysrq_showlocks_op = {
 190         .handler        = sysrq_handle_showlocks,
 191         .help_msg       = "show-all-locks(D)",
 192         .action_msg     = "Show Locks Held",
 193 };
 194 #else
 195 #define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
 196 #endif
 197
 198 static void sysrq_handle_showregs(int key, struct tty_struct *tty)
 199 {
 200         struct pt_regs *regs = get_irq_regs();
 201         if (regs)
 202                 show_regs(regs);
 203 }
 204 static struct sysrq_key_op sysrq_showregs_op = {
 205         .handler        = sysrq_handle_showregs,
 206         .help_msg       = "showPc",
 207         .action_msg     = "Show Regs",
 208         .enable_mask    = SYSRQ_ENABLE_DUMP,
 209 };
 210
 211 static void sysrq_handle_showstate(int key, struct tty_struct *tty)
 212 {
 213         show_state();
 214 }
 215 static struct sysrq_key_op sysrq_showstate_op = {
 216         .handler        = sysrq_handle_showstate,
 217         .help_msg       = "showTasks",
 218         .action_msg     = "Show State",
 219         .enable_mask    = SYSRQ_ENABLE_DUMP,
 220 };
 221
 222 static void sysrq_handle_showstate_blocked(int key, struct tty_struct *tty)
 223 {
 224         show_state_filter(TASK_UNINTERRUPTIBLE);
 225 }
 226 static struct sysrq_key_op sysrq_showstate_blocked_op = {
 227         .handler        = sysrq_handle_showstate_blocked,
 228         .help_msg       = "shoW-blocked-tasks",
 229         .action_msg     = "Show Blocked State",
 230         .enable_mask    = SYSRQ_ENABLE_DUMP,
 231 };
 232
 233
 234 static void sysrq_handle_showmem(int key, struct tty_struct *tty)
 235 {
 236         show_mem();
 237 }
 238 static struct sysrq_key_op sysrq_showmem_op = {
 239         .handler        = sysrq_handle_showmem,
 240         .help_msg       = "showMem",
 241         .action_msg     = "Show Memory",
 242         .enable_mask    = SYSRQ_ENABLE_DUMP,
 243 };
 244
 245 /*
 246  * Signal sysrq helper function.  Sends a signal to all user processes.
 247  */
 248 static void send_sig_all(int sig)
 249 {
 250         struct task_struct *p;
 251
 252         for_each_process(p) {
 253                 if (p->mm && !is_init(p))
 254                         /* Not swapper, init nor kernel thread */
 255                         force_sig(sig, p);
 256         }
 257 }
 258
 259 static void sysrq_handle_term(int key, struct tty_struct *tty)
 260 {
 261         send_sig_all(SIGTERM);
 262         console_loglevel = 8;
 263 }
 264 static struct sysrq_key_op sysrq_term_op = {
 265         .handler        = sysrq_handle_term,
 266         .help_msg       = "tErm",
 267         .action_msg     = "Terminate All Tasks",
 268         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
 269 };
 270
 271 static void moom_callback(struct work_struct *ignored)
 272 {
 273         out_of_memory(&NODE_DATA(0)->node_zonelists[ZONE_NORMAL],
 274                         GFP_KERNEL, 0);
 275 }
 276
 277 static DECLARE_WORK(moom_work, moom_callback);
 278
 279 static void sysrq_handle_moom(int key, struct tty_struct *tty)
 280 {
 281         schedule_work(&moom_work);
 282 }
 283 static struct sysrq_key_op sysrq_moom_op = {
 284         .handler        = sysrq_handle_moom,
 285         .help_msg       = "Full",
 286         .action_msg     = "Manual OOM execution",
 287 };
 288
 289 static void sysrq_handle_kill(int key, struct tty_struct *tty)
 290 {
 291         send_sig_all(SIGKILL);
 292         console_loglevel = 8;
 293 }
 294 static struct sysrq_key_op sysrq_kill_op = {
 295         .handler        = sysrq_handle_kill,
 296         .help_msg       = "kIll",
 297         .action_msg     = "Kill All Tasks",
 298         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
 299 };
 300
 301 static void sysrq_handle_unrt(int key, struct tty_struct *tty)
 302 {
 303         normalize_rt_tasks();
 304 }
 305 static struct sysrq_key_op sysrq_unrt_op = {
 306         .handler        = sysrq_handle_unrt,
 307         .help_msg       = "Nice",
 308         .action_msg     = "Nice All RT Tasks",
 309         .enable_mask    = SYSRQ_ENABLE_RTNICE,
 310 };
 311
 312 /* Key Operations table and lock */
 313 static DEFINE_SPINLOCK(sysrq_key_table_lock);
 314
 315 static struct sysrq_key_op *sysrq_key_table[36] = {
 316         &sysrq_loglevel_op,             /* 0 */
 317         &sysrq_loglevel_op,             /* 1 */
 318         &sysrq_loglevel_op,             /* 2 */
 319         &sysrq_loglevel_op,             /* 3 */
 320         &sysrq_loglevel_op,             /* 4 */
 321         &sysrq_loglevel_op,             /* 5 */
 322         &sysrq_loglevel_op,             /* 6 */
 323         &sysrq_loglevel_op,             /* 7 */
 324         &sysrq_loglevel_op,             /* 8 */
 325         &sysrq_loglevel_op,             /* 9 */
 326
 327         /*
 328          * a: Don't use for system provided sysrqs, it is handled specially on
 329          * sparc and will never arrive.
 330          */
 331         NULL,                           /* a */
 332         &sysrq_reboot_op,               /* b */
 333         &sysrq_crashdump_op,            /* c & ibm_emac driver debug */
 334         &sysrq_showlocks_op,            /* d */
 335         &sysrq_term_op,                 /* e */
 336         &sysrq_moom_op,                 /* f */
 337         /* g: May be registered by ppc for kgdb */
 338         NULL,                           /* g */
 339         NULL,                           /* h */
 340         &sysrq_kill_op,                 /* i */
 341         NULL,                           /* j */
 342         &sysrq_SAK_op,                  /* k */
 343         NULL,                           /* l */
 344         &sysrq_showmem_op,              /* m */
 345         &sysrq_unrt_op,                 /* n */
 346         /* o: This will often be registered as 'Off' at init time */
 347         NULL,                           /* o */
 348         &sysrq_showregs_op,             /* p */
 349         &sysrq_show_timers_op,          /* q */
 350         &sysrq_unraw_op,                /* r */
 351         &sysrq_sync_op,                 /* s */
 352         &sysrq_showstate_op,            /* t */
 353         &sysrq_mountro_op,              /* u */
 354         /* v: May be registered at init time by SMP VOYAGER */
 355         NULL,                           /* v */
 356         &sysrq_showstate_blocked_op,    /* w */
 357         /* x: May be registered on ppc/powerpc for xmon */
 358         NULL,                           /* x */
 359         NULL,                           /* y */
 360         NULL                            /* z */
 361 };
 362
 363 /* key2index calculation, -1 on invalid index */
 364 static int sysrq_key_table_key2index(int key)
 365 {
 366         int retval;
 367
 368         if ((key >= '0') && (key <= '9'))
 369                 retval = key - '0';
 370         else if ((key >= 'a') && (key <= 'z'))
 371                 retval = key + 10 - 'a';
 372         else
 373                 retval = -1;
 374         return retval;
 375 }
 376
 377 /*
 378  * get and put functions for the table, exposed to modules.
 379  */
 380 struct sysrq_key_op *__sysrq_get_key_op(int key)
 381 {
 382         struct sysrq_key_op *op_p = NULL;
 383         int i;
 384
 385         i = sysrq_key_table_key2index(key);
 386         if (i != -1)
 387                 op_p = sysrq_key_table[i];
 388         return op_p;
 389 }
 390
 391 static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
 392 {
 393         int i = sysrq_key_table_key2index(key);
 394
 395         if (i != -1)
 396                 sysrq_key_table[i] = op_p;
 397 }
 398
 399 /*
 400  * This is the non-locking version of handle_sysrq.  It must/can only be called
 401  * by sysrq key handlers, as they are inside of the lock
 402  */
 403 void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
 404 {
 405         struct sysrq_key_op *op_p;
 406         int orig_log_level;
 407         int i;
 408         unsigned long flags;
 409
 410         spin_lock_irqsave(&sysrq_key_table_lock, flags);
 411         orig_log_level = console_loglevel;
 412         console_loglevel = 7;
 413         printk(KERN_INFO "SysRq : ");
 414
 415         op_p = __sysrq_get_key_op(key);
 416         if (op_p) {
 417                 /*
 418                  * Should we check for enabled operations (/proc/sysrq-trigger
 419                  * should not) and is the invoked operation enabled?
 420                  */
 421                 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
 422                         printk("%s\n", op_p->action_msg);
 423                         console_loglevel = orig_log_level;
 424                         op_p->handler(key, tty);
 425                 } else {
 426                         printk("This sysrq operation is disabled.\n");
 427                 }
 428         } else {
 429                 printk("HELP : ");
 430                 /* Only print the help msg once per handler */
 431                 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
 432                         if (sysrq_key_table[i]) {
 433                                 int j;
 434
 435                                 for (j = 0; sysrq_key_table[i] !=
 436                                                 sysrq_key_table[j]; j++)
 437                                         ;
 438                                 if (j != i)
 439                                         continue;
 440                                 printk("%s ", sysrq_key_table[i]->help_msg);
 441                         }
 442                 }
 443                 printk("\n");
 444                 console_loglevel = orig_log_level;
 445         }
 446         spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
 447 }
 448
 449 /*
 450  * This function is called by the keyboard handler when SysRq is pressed
 451  * and any other keycode arrives.
 452  */
 453 void handle_sysrq(int key, struct tty_struct *tty)
 454 {
 455         if (sysrq_on())
 456                 __handle_sysrq(key, tty, 1);
 457 }
 458 EXPORT_SYMBOL(handle_sysrq);
 459
 460 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
 461                                 struct sysrq_key_op *remove_op_p)
 462 {
 463
 464         int retval;
 465         unsigned long flags;
 466
 467         spin_lock_irqsave(&sysrq_key_table_lock, flags);
 468         if (__sysrq_get_key_op(key) == remove_op_p) {
 469                 __sysrq_put_key_op(key, insert_op_p);
 470                 retval = 0;
 471         } else {
 472                 retval = -1;
 473         }
 474         spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
 475         return retval;
 476 }
 477
 478 int register_sysrq_key(int key, struct sysrq_key_op *op_p)
 479 {
 480         return __sysrq_swap_key_ops(key, op_p, NULL);
 481 }
 482 EXPORT_SYMBOL(register_sysrq_key);
 483
 484 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
 485 {
 486         return __sysrq_swap_key_ops(key, NULL, op_p);
 487 }
 488 EXPORT_SYMBOL(unregister_sysrq_key);