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