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/config.h>
  16 #include <linux/sched.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/mm.h>
  19 #include <linux/fs.h>
  20 #include <linux/tty.h>
  21 #include <linux/mount.h>
  22 #include <linux/kdev_t.h>
  23 #include <linux/major.h>
  24 #include <linux/reboot.h>
  25 #include <linux/sysrq.h>
  26 #include <linux/kbd_kern.h>
  27 #include <linux/quotaops.h>
  28 #include <linux/smp_lock.h>
  29 #include <linux/kernel.h>
  30 #include <linux/module.h>
  31 #include <linux/suspend.h>
  32 #include <linux/writeback.h>
  33 #include <linux/buffer_head.h>          /* for fsync_bdev() */
  34 #include <linux/swap.h>
  35 #include <linux/spinlock.h>
  36 #include <linux/vt_kern.h>
  37 #include <linux/workqueue.h>
  38 #include <linux/kexec.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 pt_regs *pt_regs,
  46                                   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 pt_regs *pt_regs,
  63                              struct tty_struct *tty)
  64 {
  65         if (tty)
  66                 do_SAK(tty);
  67         reset_vc(vc_cons[fg_console].d);
  68 }
  69 static struct sysrq_key_op sysrq_SAK_op = {
  70         .handler        = sysrq_handle_SAK,
  71         .help_msg       = "saK",
  72         .action_msg     = "SAK",
  73         .enable_mask    = SYSRQ_ENABLE_KEYBOARD,
  74 };
  75 #else
  76 #define sysrq_SAK_op (*(struct sysrq_key_op *)0)
  77 #endif
  78
  79 #ifdef CONFIG_VT
  80 static void sysrq_handle_unraw(int key, struct pt_regs *pt_regs,
  81                                struct tty_struct *tty)
  82 {
  83         struct kbd_struct *kbd = &kbd_table[fg_console];
  84
  85         if (kbd)
  86                 kbd->kbdmode = VC_XLATE;
  87 }
  88 static struct sysrq_key_op sysrq_unraw_op = {
  89         .handler        = sysrq_handle_unraw,
  90         .help_msg       = "unRaw",
  91         .action_msg     = "Keyboard mode set to XLATE",
  92         .enable_mask    = SYSRQ_ENABLE_KEYBOARD,
  93 };
  94 #else
  95 #define sysrq_unraw_op (*(struct sysrq_key_op *)0)
  96 #endif /* CONFIG_VT */
  97
  98 #ifdef CONFIG_KEXEC
  99 static void sysrq_handle_crashdump(int key, struct pt_regs *pt_regs,
 100                                 struct tty_struct *tty)
 101 {
 102         crash_kexec(pt_regs);
 103 }
 104 static struct sysrq_key_op sysrq_crashdump_op = {
 105         .handler        = sysrq_handle_crashdump,
 106         .help_msg       = "Crashdump",
 107         .action_msg     = "Trigger a crashdump",
 108         .enable_mask    = SYSRQ_ENABLE_DUMP,
 109 };
 110 #else
 111 #define sysrq_crashdump_op (*(struct sysrq_key_op *)0)
 112 #endif
 113
 114 static void sysrq_handle_reboot(int key, struct pt_regs *pt_regs,
 115                                 struct tty_struct *tty)
 116 {
 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_DEBUG_MUTEXES
 152 static void sysrq_handle_showlocks(int key, struct pt_regs *pt_regs,
 153                                 struct tty_struct *tty)
 154 {
 155         mutex_debug_show_all_locks();
 156 }
 157 static struct sysrq_key_op sysrq_showlocks_op = {
 158         .handler        = sysrq_handle_showlocks,
 159         .help_msg       = "show-all-locks(D)",
 160         .action_msg     = "Show Locks Held",
 161 };
 162 #else
 163 #define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
 164 #endif
 165
 166 static void sysrq_handle_showregs(int key, struct pt_regs *pt_regs,
 167                                   struct tty_struct *tty)
 168 {
 169         if (pt_regs)
 170                 show_regs(pt_regs);
 171 }
 172 static struct sysrq_key_op sysrq_showregs_op = {
 173         .handler        = sysrq_handle_showregs,
 174         .help_msg       = "showPc",
 175         .action_msg     = "Show Regs",
 176         .enable_mask    = SYSRQ_ENABLE_DUMP,
 177 };
 178
 179 static void sysrq_handle_showstate(int key, struct pt_regs *pt_regs,
 180                                    struct tty_struct *tty)
 181 {
 182         show_state();
 183 }
 184 static struct sysrq_key_op sysrq_showstate_op = {
 185         .handler        = sysrq_handle_showstate,
 186         .help_msg       = "showTasks",
 187         .action_msg     = "Show State",
 188         .enable_mask    = SYSRQ_ENABLE_DUMP,
 189 };
 190
 191 static void sysrq_handle_showmem(int key, struct pt_regs *pt_regs,
 192                                  struct tty_struct *tty)
 193 {
 194         show_mem();
 195 }
 196 static struct sysrq_key_op sysrq_showmem_op = {
 197         .handler        = sysrq_handle_showmem,
 198         .help_msg       = "showMem",
 199         .action_msg     = "Show Memory",
 200         .enable_mask    = SYSRQ_ENABLE_DUMP,
 201 };
 202
 203 /*
 204  * Signal sysrq helper function.  Sends a signal to all user processes.
 205  */
 206 static void send_sig_all(int sig)
 207 {
 208         struct task_struct *p;
 209
 210         for_each_process(p) {
 211                 if (p->mm && p->pid != 1)
 212                         /* Not swapper, init nor kernel thread */
 213                         force_sig(sig, p);
 214         }
 215 }
 216
 217 static void sysrq_handle_term(int key, struct pt_regs *pt_regs,
 218                               struct tty_struct *tty)
 219 {
 220         send_sig_all(SIGTERM);
 221         console_loglevel = 8;
 222 }
 223 static struct sysrq_key_op sysrq_term_op = {
 224         .handler        = sysrq_handle_term,
 225         .help_msg       = "tErm",
 226         .action_msg     = "Terminate All Tasks",
 227         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
 228 };
 229
 230 static void moom_callback(void *ignored)
 231 {
 232         out_of_memory(&NODE_DATA(0)->node_zonelists[ZONE_NORMAL],
 233                         GFP_KERNEL, 0);
 234 }
 235
 236 static DECLARE_WORK(moom_work, moom_callback, NULL);
 237
 238 static void sysrq_handle_moom(int key, struct pt_regs *pt_regs,
 239                               struct tty_struct *tty)
 240 {
 241         schedule_work(&moom_work);
 242 }
 243 static struct sysrq_key_op sysrq_moom_op = {
 244         .handler        = sysrq_handle_moom,
 245         .help_msg       = "Full",
 246         .action_msg     = "Manual OOM execution",
 247 };
 248
 249 static void sysrq_handle_kill(int key, struct pt_regs *pt_regs,
 250                               struct tty_struct *tty)
 251 {
 252         send_sig_all(SIGKILL);
 253         console_loglevel = 8;
 254 }
 255 static struct sysrq_key_op sysrq_kill_op = {
 256         .handler        = sysrq_handle_kill,
 257         .help_msg       = "kIll",
 258         .action_msg     = "Kill All Tasks",
 259         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
 260 };
 261
 262 static void sysrq_handle_unrt(int key, struct pt_regs *pt_regs,
 263                                 struct tty_struct *tty)
 264 {
 265         normalize_rt_tasks();
 266 }
 267 static struct sysrq_key_op sysrq_unrt_op = {
 268         .handler        = sysrq_handle_unrt,
 269         .help_msg       = "Nice",
 270         .action_msg     = "Nice All RT Tasks",
 271         .enable_mask    = SYSRQ_ENABLE_RTNICE,
 272 };
 273
 274 /* Key Operations table and lock */
 275 static DEFINE_SPINLOCK(sysrq_key_table_lock);
 276
 277 static struct sysrq_key_op *sysrq_key_table[36] = {
 278         &sysrq_loglevel_op,             /* 0 */
 279         &sysrq_loglevel_op,             /* 1 */
 280         &sysrq_loglevel_op,             /* 2 */
 281         &sysrq_loglevel_op,             /* 3 */
 282         &sysrq_loglevel_op,             /* 4 */
 283         &sysrq_loglevel_op,             /* 5 */
 284         &sysrq_loglevel_op,             /* 6 */
 285         &sysrq_loglevel_op,             /* 7 */
 286         &sysrq_loglevel_op,             /* 8 */
 287         &sysrq_loglevel_op,             /* 9 */
 288
 289         /*
 290          * Don't use for system provided sysrqs, it is handled specially on
 291          * sparc and will never arrive
 292          */
 293         NULL,                           /* a */
 294         &sysrq_reboot_op,               /* b */
 295         &sysrq_crashdump_op,            /* c */
 296         &sysrq_showlocks_op,            /* d */
 297         &sysrq_term_op,                 /* e */
 298         &sysrq_moom_op,                 /* f */
 299         NULL,                           /* g */
 300         NULL,                           /* h */
 301         &sysrq_kill_op,                 /* i */
 302         NULL,                           /* j */
 303         &sysrq_SAK_op,                  /* k */
 304         NULL,                           /* l */
 305         &sysrq_showmem_op,              /* m */
 306         &sysrq_unrt_op,                 /* n */
 307         /* This will often be registered as 'Off' at init time */
 308         NULL,                           /* o */
 309         &sysrq_showregs_op,             /* p */
 310         NULL,                           /* q */
 311         &sysrq_unraw_op,                        /* r */
 312         &sysrq_sync_op,                 /* s */
 313         &sysrq_showstate_op,            /* t */
 314         &sysrq_mountro_op,              /* u */
 315         /* May be assigned at init time by SMP VOYAGER */
 316         NULL,                           /* v */
 317         NULL,                           /* w */
 318         NULL,                           /* x */
 319         NULL,                           /* y */
 320         NULL                            /* z */
 321 };
 322
 323 /* key2index calculation, -1 on invalid index */
 324 static int sysrq_key_table_key2index(int key)
 325 {
 326         int retval;
 327
 328         if ((key >= '0') && (key <= '9'))
 329                 retval = key - '0';
 330         else if ((key >= 'a') && (key <= 'z'))
 331                 retval = key + 10 - 'a';
 332         else
 333                 retval = -1;
 334         return retval;
 335 }
 336
 337 /*
 338  * get and put functions for the table, exposed to modules.
 339  */
 340 struct sysrq_key_op *__sysrq_get_key_op(int key)
 341 {
 342         struct sysrq_key_op *op_p = NULL;
 343         int i;
 344
 345         i = sysrq_key_table_key2index(key);
 346         if (i != -1)
 347                 op_p = sysrq_key_table[i];
 348         return op_p;
 349 }
 350
 351 static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
 352 {
 353         int i = sysrq_key_table_key2index(key);
 354
 355         if (i != -1)
 356                 sysrq_key_table[i] = op_p;
 357 }
 358
 359 /*
 360  * This is the non-locking version of handle_sysrq.  It must/can only be called
 361  * by sysrq key handlers, as they are inside of the lock
 362  */
 363 void __handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty,
 364                         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, pt_regs, 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 pt_regs *pt_regs, struct tty_struct *tty)
 416 {
 417         if (!sysrq_enabled)
 418                 return;
 419         __handle_sysrq(key, pt_regs, 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);