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 /* Loglevel sysrq handler */
  46 static void sysrq_handle_loglevel(int key, struct pt_regs *pt_regs,
  47                                   struct tty_struct *tty)
  48 {
  49         int i;
  50         i = key - '0';
  51         console_loglevel = 7;
  52         printk("Loglevel set to %d\n", i);
  53         console_loglevel = i;
  54 }
  55 static struct sysrq_key_op sysrq_loglevel_op = {
  56         .handler        = sysrq_handle_loglevel,
  57         .help_msg       = "loglevel0-8",
  58         .action_msg     = "Changing Loglevel",
  59         .enable_mask    = SYSRQ_ENABLE_LOG,
  60 };
  61
  62
  63 /* SAK sysrq handler */
  64 #ifdef CONFIG_VT
  65 static void sysrq_handle_SAK(int key, struct pt_regs *pt_regs,
  66                              struct tty_struct *tty)
  67 {
  68         if (tty)
  69                 do_SAK(tty);
  70         reset_vc(vc_cons[fg_console].d);
  71 }
  72 static struct sysrq_key_op sysrq_SAK_op = {
  73         .handler        = sysrq_handle_SAK,
  74         .help_msg       = "saK",
  75         .action_msg     = "SAK",
  76         .enable_mask    = SYSRQ_ENABLE_KEYBOARD,
  77 };
  78 #endif
  79
  80 #ifdef CONFIG_VT
  81 /* unraw sysrq handler */
  82 static void sysrq_handle_unraw(int key, struct pt_regs *pt_regs,
  83                                struct tty_struct *tty)
  84 {
  85         struct kbd_struct *kbd = &kbd_table[fg_console];
  86
  87         if (kbd)
  88                 kbd->kbdmode = VC_XLATE;
  89 }
  90 static struct sysrq_key_op sysrq_unraw_op = {
  91         .handler        = sysrq_handle_unraw,
  92         .help_msg       = "unRaw",
  93         .action_msg     = "Keyboard mode set to XLATE",
  94         .enable_mask    = SYSRQ_ENABLE_KEYBOARD,
  95 };
  96 #endif /* CONFIG_VT */
  97
  98 #ifdef CONFIG_KEXEC
  99 /* crashdump sysrq handler */
 100 static void sysrq_handle_crashdump(int key, struct pt_regs *pt_regs,
 101                                 struct tty_struct *tty)
 102 {
 103         crash_kexec(pt_regs);
 104 }
 105 static struct sysrq_key_op sysrq_crashdump_op = {
 106         .handler        = sysrq_handle_crashdump,
 107         .help_msg       = "Crashdump",
 108         .action_msg     = "Trigger a crashdump",
 109         .enable_mask    = SYSRQ_ENABLE_DUMP,
 110 };
 111 #endif
 112
 113 /* reboot sysrq handler */
 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
 121 static struct sysrq_key_op sysrq_reboot_op = {
 122         .handler        = sysrq_handle_reboot,
 123         .help_msg       = "reBoot",
 124         .action_msg     = "Resetting",
 125         .enable_mask    = SYSRQ_ENABLE_BOOT,
 126 };
 127
 128 static void sysrq_handle_sync(int key, struct pt_regs *pt_regs,
 129                               struct tty_struct *tty)
 130 {
 131         emergency_sync();
 132 }
 133
 134 static struct sysrq_key_op sysrq_sync_op = {
 135         .handler        = sysrq_handle_sync,
 136         .help_msg       = "Sync",
 137         .action_msg     = "Emergency Sync",
 138         .enable_mask    = SYSRQ_ENABLE_SYNC,
 139 };
 140
 141 static void sysrq_handle_mountro(int key, struct pt_regs *pt_regs,
 142                                  struct tty_struct *tty)
 143 {
 144         emergency_remount();
 145 }
 146
 147 static struct sysrq_key_op sysrq_mountro_op = {
 148         .handler        = sysrq_handle_mountro,
 149         .help_msg       = "Unmount",
 150         .action_msg     = "Emergency Remount R/O",
 151         .enable_mask    = SYSRQ_ENABLE_REMOUNT,
 152 };
 153
 154 /* END SYNC SYSRQ HANDLERS BLOCK */
 155
 156
 157 /* SHOW SYSRQ HANDLERS BLOCK */
 158
 159 static void sysrq_handle_showregs(int key, struct pt_regs *pt_regs,
 160                                   struct tty_struct *tty)
 161 {
 162         if (pt_regs)
 163                 show_regs(pt_regs);
 164 }
 165 static struct sysrq_key_op sysrq_showregs_op = {
 166         .handler        = sysrq_handle_showregs,
 167         .help_msg       = "showPc",
 168         .action_msg     = "Show Regs",
 169         .enable_mask    = SYSRQ_ENABLE_DUMP,
 170 };
 171
 172
 173 static void sysrq_handle_showstate(int key, struct pt_regs *pt_regs,
 174                                    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
 186 static void sysrq_handle_showmem(int key, struct pt_regs *pt_regs,
 187                                  struct tty_struct *tty)
 188 {
 189         show_mem();
 190 }
 191 static struct sysrq_key_op sysrq_showmem_op = {
 192         .handler        = sysrq_handle_showmem,
 193         .help_msg       = "showMem",
 194         .action_msg     = "Show Memory",
 195         .enable_mask    = SYSRQ_ENABLE_DUMP,
 196 };
 197
 198 /* SHOW SYSRQ HANDLERS BLOCK */
 199
 200
 201 /* SIGNAL SYSRQ HANDLERS BLOCK */
 202
 203 /* signal sysrq helper function
 204  * Sends a signal to all user processes */
 205 static void send_sig_all(int sig)
 206 {
 207         struct task_struct *p;
 208
 209         for_each_process(p) {
 210                 if (p->mm && p->pid != 1)
 211                         /* Not swapper, init nor kernel thread */
 212                         force_sig(sig, p);
 213         }
 214 }
 215
 216 static void sysrq_handle_term(int key, struct pt_regs *pt_regs,
 217                               struct tty_struct *tty)
 218 {
 219         send_sig_all(SIGTERM);
 220         console_loglevel = 8;
 221 }
 222 static struct sysrq_key_op sysrq_term_op = {
 223         .handler        = sysrq_handle_term,
 224         .help_msg       = "tErm",
 225         .action_msg     = "Terminate All Tasks",
 226         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
 227 };
 228
 229 static void moom_callback(void *ignored)
 230 {
 231         out_of_memory(GFP_KERNEL, 0);
 232 }
 233
 234 static DECLARE_WORK(moom_work, moom_callback, NULL);
 235
 236 static void sysrq_handle_moom(int key, struct pt_regs *pt_regs,
 237                               struct tty_struct *tty)
 238 {
 239         schedule_work(&moom_work);
 240 }
 241 static struct sysrq_key_op sysrq_moom_op = {
 242         .handler        = sysrq_handle_moom,
 243         .help_msg       = "Full",
 244         .action_msg     = "Manual OOM execution",
 245 };
 246
 247 static void sysrq_handle_kill(int key, struct pt_regs *pt_regs,
 248                               struct tty_struct *tty)
 249 {
 250         send_sig_all(SIGKILL);
 251         console_loglevel = 8;
 252 }
 253 static struct sysrq_key_op sysrq_kill_op = {
 254         .handler        = sysrq_handle_kill,
 255         .help_msg       = "kIll",
 256         .action_msg     = "Kill All Tasks",
 257         .enable_mask    = SYSRQ_ENABLE_SIGNAL,
 258 };
 259
 260 /* END SIGNAL SYSRQ HANDLERS BLOCK */
 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 #define SYSRQ_KEY_TABLE_LENGTH 36
 277 static struct sysrq_key_op *sysrq_key_table[SYSRQ_KEY_TABLE_LENGTH] = {
 278 /* 0 */ &sysrq_loglevel_op,
 279 /* 1 */ &sysrq_loglevel_op,
 280 /* 2 */ &sysrq_loglevel_op,
 281 /* 3 */ &sysrq_loglevel_op,
 282 /* 4 */ &sysrq_loglevel_op,
 283 /* 5 */ &sysrq_loglevel_op,
 284 /* 6 */ &sysrq_loglevel_op,
 285 /* 7 */ &sysrq_loglevel_op,
 286 /* 8 */ &sysrq_loglevel_op,
 287 /* 9 */ &sysrq_loglevel_op,
 288 /* a */ NULL, /* Don't use for system provided sysrqs,
 289                  it is handled specially on the sparc
 290                  and will never arrive */
 291 /* b */ &sysrq_reboot_op,
 292 #ifdef CONFIG_KEXEC
 293 /* c */ &sysrq_crashdump_op,
 294 #else
 295 /* c */ NULL,
 296 #endif
 297 /* d */ NULL,
 298 /* e */ &sysrq_term_op,
 299 /* f */ &sysrq_moom_op,
 300 /* g */ NULL,
 301 /* h */ NULL,
 302 /* i */ &sysrq_kill_op,
 303 /* j */ NULL,
 304 #ifdef CONFIG_VT
 305 /* k */ &sysrq_SAK_op,
 306 #else
 307 /* k */ NULL,
 308 #endif
 309 /* l */ NULL,
 310 /* m */ &sysrq_showmem_op,
 311 /* n */ &sysrq_unrt_op,
 312 /* o */ NULL, /* This will often be registered
 313                  as 'Off' at init time */
 314 /* p */ &sysrq_showregs_op,
 315 /* q */ NULL,
 316 #ifdef CONFIG_VT
 317 /* r */ &sysrq_unraw_op,
 318 #else
 319 /* r */ NULL,
 320 #endif
 321 /* s */ &sysrq_sync_op,
 322 /* t */ &sysrq_showstate_op,
 323 /* u */ &sysrq_mountro_op,
 324 /* v */ NULL, /* May be assigned at init time by SMP VOYAGER */
 325 /* w */ NULL,
 326 /* x */ NULL,
 327 /* y */ NULL,
 328 /* z */ NULL
 329 };
 330
 331 /* key2index calculation, -1 on invalid index */
 332 static int sysrq_key_table_key2index(int key) {
 333         int retval;
 334         if ((key >= '0') && (key <= '9')) {
 335                 retval = key - '0';
 336         } else if ((key >= 'a') && (key <= 'z')) {
 337                 retval = key + 10 - 'a';
 338         } else {
 339                 retval = -1;
 340         }
 341         return retval;
 342 }
 343
 344 /*
 345  * get and put functions for the table, exposed to modules.
 346  */
 347
 348 struct sysrq_key_op *__sysrq_get_key_op (int key) {
 349         struct sysrq_key_op *op_p;
 350         int i;
 351
 352         i = sysrq_key_table_key2index(key);
 353         op_p = (i == -1) ? NULL : sysrq_key_table[i];
 354         return op_p;
 355 }
 356
 357 static void __sysrq_put_key_op (int key, struct sysrq_key_op *op_p) {
 358         int i;
 359
 360         i = sysrq_key_table_key2index(key);
 361         if (i != -1)
 362                 sysrq_key_table[i] = op_p;
 363 }
 364
 365 /*
 366  * This is the non-locking version of handle_sysrq
 367  * It must/can only be called by sysrq key handlers,
 368  * as they are inside of the lock
 369  */
 370
 371 void __handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty, int check_mask)
 372 {
 373         struct sysrq_key_op *op_p;
 374         int orig_log_level;
 375         int i, j;
 376         unsigned long flags;
 377
 378         spin_lock_irqsave(&sysrq_key_table_lock, flags);
 379         orig_log_level = console_loglevel;
 380         console_loglevel = 7;
 381         printk(KERN_INFO "SysRq : ");
 382
 383         op_p = __sysrq_get_key_op(key);
 384         if (op_p) {
 385                 /* Should we check for enabled operations (/proc/sysrq-trigger should not)
 386                  * and is the invoked operation enabled? */
 387                 if (!check_mask || sysrq_enabled == 1 ||
 388                     (sysrq_enabled & op_p->enable_mask)) {
 389                         printk ("%s\n", op_p->action_msg);
 390                         console_loglevel = orig_log_level;
 391                         op_p->handler(key, pt_regs, tty);
 392                 }
 393                 else
 394                         printk("This sysrq operation is disabled.\n");
 395         } else {
 396                 printk("HELP : ");
 397                 /* Only print the help msg once per handler */
 398                 for (i=0; i<SYSRQ_KEY_TABLE_LENGTH; i++)
 399                 if (sysrq_key_table[i]) {
 400                         for (j=0; sysrq_key_table[i] != sysrq_key_table[j]; j++);
 401                         if (j == i)
 402                                 printk ("%s ", sysrq_key_table[i]->help_msg);
 403                 }
 404                 printk ("\n");
 405                 console_loglevel = orig_log_level;
 406         }
 407         spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
 408 }
 409
 410 /*
 411  * This function is called by the keyboard handler when SysRq is pressed
 412  * and any other keycode arrives.
 413  */
 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
 422 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
 423                                 struct sysrq_key_op *remove_op_p) {
 424
 425         int retval;
 426         unsigned long flags;
 427
 428         spin_lock_irqsave(&sysrq_key_table_lock, flags);
 429         if (__sysrq_get_key_op(key) == remove_op_p) {
 430                 __sysrq_put_key_op(key, insert_op_p);
 431                 retval = 0;
 432         } else {
 433                 retval = -1;
 434         }
 435         spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
 436
 437         return retval;
 438 }
 439
 440 int register_sysrq_key(int key, struct sysrq_key_op *op_p)
 441 {
 442         return __sysrq_swap_key_ops(key, op_p, NULL);
 443 }
 444
 445 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
 446 {
 447         return __sysrq_swap_key_ops(key, NULL, op_p);
 448 }
 449
 450 EXPORT_SYMBOL(handle_sysrq);
 451 EXPORT_SYMBOL(register_sysrq_key);
 452 EXPORT_SYMBOL(unregister_sysrq_key);