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 sysrq_enabled = 1;
  45
  46 static void sysrq_handle_loglevel(int key, struct tty_struct *tty)
  47 {
  48         int i;
  49         i = key - '0';
  50         console_loglevel = 7;
  51         printk("Loglevel set to %d\n", i);
  52         console_loglevel = i;
  53 }
  54 static struct sysrq_key_op sysrq_loglevel_op = {
  55         .handler        = sysrq_handle_loglevel,
  56         .help_msg       = "loglevel0-8",
  57         .action_msg     = "Changing Loglevel",
  58         .enable_mask    = SYSRQ_ENABLE_LOG,
  59 };
  60
  61 #ifdef CONFIG_VT
  62 static void sysrq_handle_SAK(int key, 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 tty_struct *tty)
  80 {
  81         struct kbd_struct *kbd = &kbd_table[fg_console];
  82
  83         if (kbd)
  84                 kbd->kbdmode = VC_XLATE;
  85 }
  86 static struct sysrq_key_op sysrq_unraw_op = {
  87         .handler        = sysrq_handle_unraw,
  88         .help_msg       = "unRaw",
  89         .action_msg     = "Keyboard mode set to XLATE",
  90         .enable_mask    = SYSRQ_ENABLE_KEYBOARD,
  91 };
  92 #else
  93 #define sysrq_unraw_op (*(struct sysrq_key_op *)0)
  94 #endif /* CONFIG_VT */
  95
  96 #ifdef CONFIG_KEXEC
  97 static void sysrq_handle_crashdump(int key, struct tty_struct *tty)
  98 {
  99         crash_kexec(get_irq_regs());
 100 }
 101 static struct sysrq_key_op sysrq_crashdump_op = {
 102         .handler        = sysrq_handle_crashdump,
 103         .help_msg       = "Crashdump",
 104         .action_msg     = "Trigger a crashdump",
 105         .enable_mask    = SYSRQ_ENABLE_DUMP,
 106 };
 107 #else
 108 #define sysrq_crashdump_op (*(struct sysrq_key_op *)0)
 109 #endif
 110
 111 static void sysrq_handle_reboot(int key, struct tty_struct *tty)
 112 {
 113         lockdep_off();
 114         local_irq_enable();
 115         emergency_restart();
 116 }
 117 static struct sysrq_key_op sysrq_reboot_op = {
 118         .handler        = sysrq_handle_reboot,
 119         .help_msg       = "reBoot",
 120         .action_msg     = "Resetting",
 121         .enable_mask    = SYSRQ_ENABLE_BOOT,
 122 };
 123
 124 static void sysrq_handle_sync(int key, struct tty_struct *tty)
 125 {
 126         emergency_sync();
 127 }
 128 static struct sysrq_key_op sysrq_sync_op = {
 129         .handler        = sysrq_handle_sync,
 130         .help_msg       = "Sync",
 131         .action_msg     = "Emergency Sync",
 132         .enable_mask    = SYSRQ_ENABLE_SYNC,
 133 };
 134
 135 static void sysrq_handle_mountro(int key, struct tty_struct *tty)
 136 {
 137         emergency_remount();
 138 }
 139 static struct sysrq_key_op sysrq_mountro_op = {
 140         .handler        = sysrq_handle_mountro,
 141         .help_msg       = "Unmount",
 142         .action_msg     = "Emergency Remount R/O",
 143         .enable_mask    = SYSRQ_ENABLE_REMOUNT,
 144 };
 145
 146 #ifdef CONFIG_LOCKDEP
 147 static void sysrq_handle_showlocks(int key, struct tty_struct *tty)
 148 {
 149         debug_show_all_locks();
 150 }
 151
 152 static struct sysrq_key_op sysrq_showlocks_op = {
 153         .handler        = sysrq_handle_showlocks,
 154         .help_msg       = "show-all-locks(D)",
 155         .action_msg     = "Show Locks Held",
 156 };
 157 #else
 158 #define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
 159 #endif
 160
 161 static void sysrq_handle_showregs(int key, struct tty_struct *tty)
 162 {
 163         struct pt_regs *regs = get_irq_regs();
 164         if (regs)
 165                 show_regs(regs);
 166 }
 167 static struct sysrq_key_op sysrq_showregs_op = {
 168         .handler        = sysrq_handle_showregs,
 169         .help_msg       = "showPc",
 170         .action_msg     = "Show Regs",
 171         .enable_mask    = SYSRQ_ENABLE_DUMP,
 172 };
 173
 174 static void sysrq_handle_showstate(int key, struct tty_struct *tty)
 175 {
 176         show_state();
 177 }
 178 static struct sysrq_key_op sysrq_showstate_op = {
 179         .handler        = sysrq_handle_showstate,
 180         .help_msg       = "showTasks",
 181         .action_msg     = "Show State",
 182         .enable_mask    = SYSRQ_ENABLE_DUMP,
 183 };
 184
 185 static void sysrq_handle_showstate_blocked(int key, struct tty_struct *tty)
 186 {
 187         show_state_filter(TASK_UNINTERRUPTIBLE);
 188 }
 189 static struct sysrq_key_op sysrq_showstate_blocked_op = {
 190         .handler        = sysrq_handle_showstate_blocked,
 191         .help_msg       = "showBlockedTasks",
 192         .action_msg     = "Show Blocked State",
 193         .enable_mask    = SYSRQ_ENABLE_DUMP,
 194 };
 195
 196
 197 static void sysrq_handle_showmem(int key, struct tty_struct *tty)
 198 {
 199         show_mem();
 200 }
 201 static struct sysrq_key_op sysrq_showmem_op = {
 202         .handler        = sysrq_handle_showmem,
 203         .help_msg       = "showMem",
 204         .action_msg     = "Show Memory",
 205         .enable_mask    = SYSRQ_ENABLE_DUMP,
 206 };
 207
 208 /*
 209  * Signal sysrq helper function.  Sends a signal to all user processes.
 210  */
 211 static void send_sig_all(int sig)
 212 {
 213         struct task_struct *p;
 214
 215         for_each_process(p) {
 216                 if (p->mm && !is_init(p))
 217                         /* Not swapper, init nor kernel thread */
 218                         force_sig(sig, p);
 219         }
 220 }
 221
 222 static void sysrq_handle_term(int key, struct tty_struct *tty)
 223 {
 224         send_sig_all(SIGTERM);
 225         console_loglevel = 8;
 226 }
 227 static struct sysrq_key_op sysrq_term_op = {
 228         .handler        = sysrq_handle_term,
 229         .help_msg       = "tErm",
 230         .action_msg     = "Terminate All Tasks",
 231         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
 232 };
 233
 234 static void moom_callback(struct work_struct *ignored)
 235 {
 236         out_of_memory(&NODE_DATA(0)->node_zonelists[ZONE_NORMAL],
 237                         GFP_KERNEL, 0);
 238 }
 239
 240 static DECLARE_WORK(moom_work, moom_callback);
 241
 242 static void sysrq_handle_moom(int key, struct tty_struct *tty)
 243 {
 244         schedule_work(&moom_work);
 245 }
 246 static struct sysrq_key_op sysrq_moom_op = {
 247         .handler        = sysrq_handle_moom,
 248         .help_msg       = "Full",
 249         .action_msg     = "Manual OOM execution",
 250 };
 251
 252 static void sysrq_handle_kill(int key, struct tty_struct *tty)
 253 {
 254         send_sig_all(SIGKILL);
 255         console_loglevel = 8;
 256 }
 257 static struct sysrq_key_op sysrq_kill_op = {
 258         .handler        = sysrq_handle_kill,
 259         .help_msg       = "kIll",
 260         .action_msg     = "Kill All Tasks",
 261         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
 262 };
 263
 264 static void sysrq_handle_unrt(int key, 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         &sysrq_showstate_blocked_op,    /* 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 tty_struct *tty, int check_mask)
 365 {
 366         struct sysrq_key_op *op_p;
 367         int orig_log_level;
 368         int i;
 369         unsigned long flags;
 370
 371         spin_lock_irqsave(&sysrq_key_table_lock, flags);
 372         orig_log_level = console_loglevel;
 373         console_loglevel = 7;
 374         printk(KERN_INFO "SysRq : ");
 375
 376         op_p = __sysrq_get_key_op(key);
 377         if (op_p) {
 378                 /*
 379                  * Should we check for enabled operations (/proc/sysrq-trigger
 380                  * should not) and is the invoked operation enabled?
 381                  */
 382                 if (!check_mask || sysrq_enabled == 1 ||
 383                     (sysrq_enabled & op_p->enable_mask)) {
 384                         printk("%s\n", op_p->action_msg);
 385                         console_loglevel = orig_log_level;
 386                         op_p->handler(key, tty);
 387                 } else {
 388                         printk("This sysrq operation is disabled.\n");
 389                 }
 390         } else {
 391                 printk("HELP : ");
 392                 /* Only print the help msg once per handler */
 393                 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
 394                         if (sysrq_key_table[i]) {
 395                                 int j;
 396
 397                                 for (j = 0; sysrq_key_table[i] !=
 398                                                 sysrq_key_table[j]; j++)
 399                                         ;
 400                                 if (j != i)
 401                                         continue;
 402                                 printk("%s ", sysrq_key_table[i]->help_msg);
 403                         }
 404                 }
 405                 printk("\n");
 406                 console_loglevel = orig_log_level;
 407         }
 408         spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
 409 }
 410
 411 /*
 412  * This function is called by the keyboard handler when SysRq is pressed
 413  * and any other keycode arrives.
 414  */
 415 void handle_sysrq(int key, struct tty_struct *tty)
 416 {
 417         if (!sysrq_enabled)
 418                 return;
 419         __handle_sysrq(key, tty, 1);
 420 }
 421 EXPORT_SYMBOL(handle_sysrq);
 422
 423 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
 424                                 struct sysrq_key_op *remove_op_p)
 425 {
 426
 427         int retval;
 428         unsigned long flags;
 429
 430         spin_lock_irqsave(&sysrq_key_table_lock, flags);
 431         if (__sysrq_get_key_op(key) == remove_op_p) {
 432                 __sysrq_put_key_op(key, insert_op_p);
 433                 retval = 0;
 434         } else {
 435                 retval = -1;
 436         }
 437         spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
 438         return retval;
 439 }
 440
 441 int register_sysrq_key(int key, struct sysrq_key_op *op_p)
 442 {
 443         return __sysrq_swap_key_ops(key, op_p, NULL);
 444 }
 445 EXPORT_SYMBOL(register_sysrq_key);
 446
 447 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
 448 {
 449         return __sysrq_swap_key_ops(key, NULL, op_p);
 450 }
 451 EXPORT_SYMBOL(unregister_sysrq_key);