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 #include <linux/oom.h>
  40
  41 #include <asm/ptrace.h>
  42 #include <asm/irq_regs.h>
  43
  44 /* Whether we react on sysrq keys or just ignore them */
  45 int __read_mostly __sysrq_enabled = 1;
  46
  47 static int __read_mostly sysrq_always_enabled;
  48
  49 int sysrq_on(void)
  50 {
  51         return __sysrq_enabled || sysrq_always_enabled;
  52 }
  53
  54 /*
  55  * A value of 1 means 'all', other nonzero values are an op mask:
  56  */
  57 static inline int sysrq_on_mask(int mask)
  58 {
  59         return sysrq_always_enabled || __sysrq_enabled == 1 ||
  60                                                 (__sysrq_enabled & mask);
  61 }
  62
  63 static int __init sysrq_always_enabled_setup(char *str)
  64 {
  65         sysrq_always_enabled = 1;
  66         printk(KERN_INFO "debug: sysrq always enabled.\n");
  67
  68         return 1;
  69 }
  70
  71 __setup("sysrq_always_enabled", sysrq_always_enabled_setup);
  72
  73
  74 static void sysrq_handle_loglevel(int key, struct tty_struct *tty)
  75 {
  76         int i;
  77         i = key - '0';
  78         console_loglevel = 7;
  79         printk("Loglevel set to %d\n", i);
  80         console_loglevel = i;
  81 }
  82 static struct sysrq_key_op sysrq_loglevel_op = {
  83         .handler        = sysrq_handle_loglevel,
  84         .help_msg       = "loglevel0-8",
  85         .action_msg     = "Changing Loglevel",
  86         .enable_mask    = SYSRQ_ENABLE_LOG,
  87 };
  88
  89 #ifdef CONFIG_VT
  90 static void sysrq_handle_SAK(int key, struct tty_struct *tty)
  91 {
  92         struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
  93         schedule_work(SAK_work);
  94 }
  95 static struct sysrq_key_op sysrq_SAK_op = {
  96         .handler        = sysrq_handle_SAK,
  97         .help_msg       = "saK",
  98         .action_msg     = "SAK",
  99         .enable_mask    = SYSRQ_ENABLE_KEYBOARD,
 100 };
 101 #else
 102 #define sysrq_SAK_op (*(struct sysrq_key_op *)0)
 103 #endif
 104
 105 #ifdef CONFIG_VT
 106 static void sysrq_handle_unraw(int key, struct tty_struct *tty)
 107 {
 108         struct kbd_struct *kbd = &kbd_table[fg_console];
 109
 110         if (kbd)
 111                 kbd->kbdmode = default_utf8 ? VC_UNICODE : VC_XLATE;
 112 }
 113 static struct sysrq_key_op sysrq_unraw_op = {
 114         .handler        = sysrq_handle_unraw,
 115         .help_msg       = "unRaw",
 116         .action_msg     = "Keyboard mode set to system default",
 117         .enable_mask    = SYSRQ_ENABLE_KEYBOARD,
 118 };
 119 #else
 120 #define sysrq_unraw_op (*(struct sysrq_key_op *)0)
 121 #endif /* CONFIG_VT */
 122
 123 #ifdef CONFIG_KEXEC
 124 static void sysrq_handle_crashdump(int key, struct tty_struct *tty)
 125 {
 126         crash_kexec(get_irq_regs());
 127 }
 128 static struct sysrq_key_op sysrq_crashdump_op = {
 129         .handler        = sysrq_handle_crashdump,
 130         .help_msg       = "Crashdump",
 131         .action_msg     = "Trigger a crashdump",
 132         .enable_mask    = SYSRQ_ENABLE_DUMP,
 133 };
 134 #else
 135 #define sysrq_crashdump_op (*(struct sysrq_key_op *)0)
 136 #endif
 137
 138 static void sysrq_handle_reboot(int key, struct tty_struct *tty)
 139 {
 140         lockdep_off();
 141         local_irq_enable();
 142         emergency_restart();
 143 }
 144 static struct sysrq_key_op sysrq_reboot_op = {
 145         .handler        = sysrq_handle_reboot,
 146         .help_msg       = "reBoot",
 147         .action_msg     = "Resetting",
 148         .enable_mask    = SYSRQ_ENABLE_BOOT,
 149 };
 150
 151 static void sysrq_handle_sync(int key, struct tty_struct *tty)
 152 {
 153         emergency_sync();
 154 }
 155 static struct sysrq_key_op sysrq_sync_op = {
 156         .handler        = sysrq_handle_sync,
 157         .help_msg       = "Sync",
 158         .action_msg     = "Emergency Sync",
 159         .enable_mask    = SYSRQ_ENABLE_SYNC,
 160 };
 161
 162 static void sysrq_handle_show_timers(int key, struct tty_struct *tty)
 163 {
 164         sysrq_timer_list_show();
 165 }
 166
 167 static struct sysrq_key_op sysrq_show_timers_op = {
 168         .handler        = sysrq_handle_show_timers,
 169         .help_msg       = "show-all-timers(Q)",
 170         .action_msg     = "Show Pending Timers",
 171 };
 172
 173 static void sysrq_handle_mountro(int key, struct tty_struct *tty)
 174 {
 175         emergency_remount();
 176 }
 177 static struct sysrq_key_op sysrq_mountro_op = {
 178         .handler        = sysrq_handle_mountro,
 179         .help_msg       = "Unmount",
 180         .action_msg     = "Emergency Remount R/O",
 181         .enable_mask    = SYSRQ_ENABLE_REMOUNT,
 182 };
 183
 184 #ifdef CONFIG_LOCKDEP
 185 static void sysrq_handle_showlocks(int key, struct tty_struct *tty)
 186 {
 187         debug_show_all_locks();
 188 }
 189
 190 static struct sysrq_key_op sysrq_showlocks_op = {
 191         .handler        = sysrq_handle_showlocks,
 192         .help_msg       = "show-all-locks(D)",
 193         .action_msg     = "Show Locks Held",
 194 };
 195 #else
 196 #define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
 197 #endif
 198
 199 #ifdef CONFIG_SMP
 200 static DEFINE_SPINLOCK(show_lock);
 201
 202 static void showacpu(void *dummy)
 203 {
 204         unsigned long flags;
 205
 206         /* Idle CPUs have no interesting backtrace. */
 207         if (idle_cpu(smp_processor_id()))
 208                 return;
 209
 210         spin_lock_irqsave(&show_lock, flags);
 211         printk(KERN_INFO "CPU%d:\n", smp_processor_id());
 212         show_stack(NULL, NULL);
 213         spin_unlock_irqrestore(&show_lock, flags);
 214 }
 215
 216 static void sysrq_showregs_othercpus(struct work_struct *dummy)
 217 {
 218         smp_call_function(showacpu, NULL, 0, 0);
 219 }
 220
 221 static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
 222
 223 static void sysrq_handle_showallcpus(int key, struct tty_struct *tty)
 224 {
 225         struct pt_regs *regs = get_irq_regs();
 226         if (regs) {
 227                 printk(KERN_INFO "CPU%d:\n", smp_processor_id());
 228                 show_regs(regs);
 229         }
 230         schedule_work(&sysrq_showallcpus);
 231 }
 232
 233 static struct sysrq_key_op sysrq_showallcpus_op = {
 234         .handler        = sysrq_handle_showallcpus,
 235         .help_msg       = "aLlcpus",
 236         .action_msg     = "Show backtrace of all active CPUs",
 237         .enable_mask    = SYSRQ_ENABLE_DUMP,
 238 };
 239 #endif
 240
 241 static void sysrq_handle_showregs(int key, struct tty_struct *tty)
 242 {
 243         struct pt_regs *regs = get_irq_regs();
 244         if (regs)
 245                 show_regs(regs);
 246 }
 247 static struct sysrq_key_op sysrq_showregs_op = {
 248         .handler        = sysrq_handle_showregs,
 249         .help_msg       = "showPc",
 250         .action_msg     = "Show Regs",
 251         .enable_mask    = SYSRQ_ENABLE_DUMP,
 252 };
 253
 254 static void sysrq_handle_showstate(int key, struct tty_struct *tty)
 255 {
 256         show_state();
 257 }
 258 static struct sysrq_key_op sysrq_showstate_op = {
 259         .handler        = sysrq_handle_showstate,
 260         .help_msg       = "showTasks",
 261         .action_msg     = "Show State",
 262         .enable_mask    = SYSRQ_ENABLE_DUMP,
 263 };
 264
 265 static void sysrq_handle_showstate_blocked(int key, struct tty_struct *tty)
 266 {
 267         show_state_filter(TASK_UNINTERRUPTIBLE);
 268 }
 269 static struct sysrq_key_op sysrq_showstate_blocked_op = {
 270         .handler        = sysrq_handle_showstate_blocked,
 271         .help_msg       = "shoW-blocked-tasks",
 272         .action_msg     = "Show Blocked State",
 273         .enable_mask    = SYSRQ_ENABLE_DUMP,
 274 };
 275
 276
 277 static void sysrq_handle_showmem(int key, struct tty_struct *tty)
 278 {
 279         show_mem();
 280 }
 281 static struct sysrq_key_op sysrq_showmem_op = {
 282         .handler        = sysrq_handle_showmem,
 283         .help_msg       = "showMem",
 284         .action_msg     = "Show Memory",
 285         .enable_mask    = SYSRQ_ENABLE_DUMP,
 286 };
 287
 288 /*
 289  * Signal sysrq helper function.  Sends a signal to all user processes.
 290  */
 291 static void send_sig_all(int sig)
 292 {
 293         struct task_struct *p;
 294
 295         for_each_process(p) {
 296                 if (p->mm && !is_global_init(p))
 297                         /* Not swapper, init nor kernel thread */
 298                         force_sig(sig, p);
 299         }
 300 }
 301
 302 static void sysrq_handle_term(int key, struct tty_struct *tty)
 303 {
 304         send_sig_all(SIGTERM);
 305         console_loglevel = 8;
 306 }
 307 static struct sysrq_key_op sysrq_term_op = {
 308         .handler        = sysrq_handle_term,
 309         .help_msg       = "tErm",
 310         .action_msg     = "Terminate All Tasks",
 311         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
 312 };
 313
 314 static void moom_callback(struct work_struct *ignored)
 315 {
 316         out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0);
 317 }
 318
 319 static DECLARE_WORK(moom_work, moom_callback);
 320
 321 static void sysrq_handle_moom(int key, struct tty_struct *tty)
 322 {
 323         schedule_work(&moom_work);
 324 }
 325 static struct sysrq_key_op sysrq_moom_op = {
 326         .handler        = sysrq_handle_moom,
 327         .help_msg       = "Full",
 328         .action_msg     = "Manual OOM execution",
 329 };
 330
 331 static void sysrq_handle_kill(int key, struct tty_struct *tty)
 332 {
 333         send_sig_all(SIGKILL);
 334         console_loglevel = 8;
 335 }
 336 static struct sysrq_key_op sysrq_kill_op = {
 337         .handler        = sysrq_handle_kill,
 338         .help_msg       = "kIll",
 339         .action_msg     = "Kill All Tasks",
 340         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
 341 };
 342
 343 static void sysrq_handle_unrt(int key, struct tty_struct *tty)
 344 {
 345         normalize_rt_tasks();
 346 }
 347 static struct sysrq_key_op sysrq_unrt_op = {
 348         .handler        = sysrq_handle_unrt,
 349         .help_msg       = "Nice",
 350         .action_msg     = "Nice All RT Tasks",
 351         .enable_mask    = SYSRQ_ENABLE_RTNICE,
 352 };
 353
 354 /* Key Operations table and lock */
 355 static DEFINE_SPINLOCK(sysrq_key_table_lock);
 356
 357 static struct sysrq_key_op *sysrq_key_table[36] = {
 358         &sysrq_loglevel_op,             /* 0 */
 359         &sysrq_loglevel_op,             /* 1 */
 360         &sysrq_loglevel_op,             /* 2 */
 361         &sysrq_loglevel_op,             /* 3 */
 362         &sysrq_loglevel_op,             /* 4 */
 363         &sysrq_loglevel_op,             /* 5 */
 364         &sysrq_loglevel_op,             /* 6 */
 365         &sysrq_loglevel_op,             /* 7 */
 366         &sysrq_loglevel_op,             /* 8 */
 367         &sysrq_loglevel_op,             /* 9 */
 368
 369         /*
 370          * a: Don't use for system provided sysrqs, it is handled specially on
 371          * sparc and will never arrive.
 372          */
 373         NULL,                           /* a */
 374         &sysrq_reboot_op,               /* b */
 375         &sysrq_crashdump_op,            /* c & ibm_emac driver debug */
 376         &sysrq_showlocks_op,            /* d */
 377         &sysrq_term_op,                 /* e */
 378         &sysrq_moom_op,                 /* f */
 379         /* g: May be registered by ppc for kgdb */
 380         NULL,                           /* g */
 381         NULL,                           /* h */
 382         &sysrq_kill_op,                 /* i */
 383         NULL,                           /* j */
 384         &sysrq_SAK_op,                  /* k */
 385 #ifdef CONFIG_SMP
 386         &sysrq_showallcpus_op,          /* l */
 387 #else
 388         NULL,                           /* l */
 389 #endif
 390         &sysrq_showmem_op,              /* m */
 391         &sysrq_unrt_op,                 /* n */
 392         /* o: This will often be registered as 'Off' at init time */
 393         NULL,                           /* o */
 394         &sysrq_showregs_op,             /* p */
 395         &sysrq_show_timers_op,          /* q */
 396         &sysrq_unraw_op,                /* r */
 397         &sysrq_sync_op,                 /* s */
 398         &sysrq_showstate_op,            /* t */
 399         &sysrq_mountro_op,              /* u */
 400         /* v: May be registered at init time by SMP VOYAGER */
 401         NULL,                           /* v */
 402         &sysrq_showstate_blocked_op,    /* w */
 403         /* x: May be registered on ppc/powerpc for xmon */
 404         NULL,                           /* x */
 405         NULL,                           /* y */
 406         NULL                            /* z */
 407 };
 408
 409 /* key2index calculation, -1 on invalid index */
 410 static int sysrq_key_table_key2index(int key)
 411 {
 412         int retval;
 413
 414         if ((key >= '0') && (key <= '9'))
 415                 retval = key - '0';
 416         else if ((key >= 'a') && (key <= 'z'))
 417                 retval = key + 10 - 'a';
 418         else
 419                 retval = -1;
 420         return retval;
 421 }
 422
 423 /*
 424  * get and put functions for the table, exposed to modules.
 425  */
 426 struct sysrq_key_op *__sysrq_get_key_op(int key)
 427 {
 428         struct sysrq_key_op *op_p = NULL;
 429         int i;
 430
 431         i = sysrq_key_table_key2index(key);
 432         if (i != -1)
 433                 op_p = sysrq_key_table[i];
 434         return op_p;
 435 }
 436
 437 static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
 438 {
 439         int i = sysrq_key_table_key2index(key);
 440
 441         if (i != -1)
 442                 sysrq_key_table[i] = op_p;
 443 }
 444
 445 /*
 446  * This is the non-locking version of handle_sysrq.  It must/can only be called
 447  * by sysrq key handlers, as they are inside of the lock
 448  */
 449 void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
 450 {
 451         struct sysrq_key_op *op_p;
 452         int orig_log_level;
 453         int i;
 454         unsigned long flags;
 455
 456         spin_lock_irqsave(&sysrq_key_table_lock, flags);
 457         orig_log_level = console_loglevel;
 458         console_loglevel = 7;
 459         printk(KERN_INFO "SysRq : ");
 460
 461         op_p = __sysrq_get_key_op(key);
 462         if (op_p) {
 463                 /*
 464                  * Should we check for enabled operations (/proc/sysrq-trigger
 465                  * should not) and is the invoked operation enabled?
 466                  */
 467                 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
 468                         printk("%s\n", op_p->action_msg);
 469                         console_loglevel = orig_log_level;
 470                         op_p->handler(key, tty);
 471                 } else {
 472                         printk("This sysrq operation is disabled.\n");
 473                 }
 474         } else {
 475                 printk("HELP : ");
 476                 /* Only print the help msg once per handler */
 477                 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {
 478                         if (sysrq_key_table[i]) {
 479                                 int j;
 480
 481                                 for (j = 0; sysrq_key_table[i] !=
 482                                                 sysrq_key_table[j]; j++)
 483                                         ;
 484                                 if (j != i)
 485                                         continue;
 486                                 printk("%s ", sysrq_key_table[i]->help_msg);
 487                         }
 488                 }
 489                 printk("\n");
 490                 console_loglevel = orig_log_level;
 491         }
 492         spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
 493 }
 494
 495 /*
 496  * This function is called by the keyboard handler when SysRq is pressed
 497  * and any other keycode arrives.
 498  */
 499 void handle_sysrq(int key, struct tty_struct *tty)
 500 {
 501         if (sysrq_on())
 502                 __handle_sysrq(key, tty, 1);
 503 }
 504 EXPORT_SYMBOL(handle_sysrq);
 505
 506 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
 507                                 struct sysrq_key_op *remove_op_p)
 508 {
 509
 510         int retval;
 511         unsigned long flags;
 512
 513         spin_lock_irqsave(&sysrq_key_table_lock, flags);
 514         if (__sysrq_get_key_op(key) == remove_op_p) {
 515                 __sysrq_put_key_op(key, insert_op_p);
 516                 retval = 0;
 517         } else {
 518                 retval = -1;
 519         }
 520         spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
 521         return retval;
 522 }
 523
 524 int register_sysrq_key(int key, struct sysrq_key_op *op_p)
 525 {
 526         return __sysrq_swap_key_ops(key, op_p, NULL);
 527 }
 528 EXPORT_SYMBOL(register_sysrq_key);
 529
 530 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
 531 {
 532         return __sysrq_swap_key_ops(key, NULL, op_p);
 533 }
 534 EXPORT_SYMBOL(unregister_sysrq_key);