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