| 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/proc_fs.h> |
| 27 | #include <linux/quotaops.h> |
| 28 | #include <linux/perf_counter.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 | #include <linux/hrtimer.h> |
| 40 | #include <linux/oom.h> |
| 41 | |
| 42 | #include <asm/ptrace.h> |
| 43 | #include <asm/irq_regs.h> |
| 44 | |
| 45 | /* Whether we react on sysrq keys or just ignore them */ |
| 46 | int __read_mostly __sysrq_enabled = 1; |
| 47 | |
| 48 | static int __read_mostly sysrq_always_enabled; |
| 49 | |
| 50 | int sysrq_on(void) |
| 51 | { |
| 52 | return __sysrq_enabled || sysrq_always_enabled; |
| 53 | } |
| 54 | |
| 55 | /* |
| 56 | * A value of 1 means 'all', other nonzero values are an op mask: |
| 57 | */ |
| 58 | static inline int sysrq_on_mask(int mask) |
| 59 | { |
| 60 | return sysrq_always_enabled || __sysrq_enabled == 1 || |
| 61 | (__sysrq_enabled & mask); |
| 62 | } |
| 63 | |
| 64 | static int __init sysrq_always_enabled_setup(char *str) |
| 65 | { |
| 66 | sysrq_always_enabled = 1; |
| 67 | printk(KERN_INFO "debug: sysrq always enabled.\n"); |
| 68 | |
| 69 | return 1; |
| 70 | } |
| 71 | |
| 72 | __setup("sysrq_always_enabled", sysrq_always_enabled_setup); |
| 73 | |
| 74 | |
| 75 | static void sysrq_handle_loglevel(int key, struct tty_struct *tty) |
| 76 | { |
| 77 | int i; |
| 78 | i = key - '0'; |
| 79 | console_loglevel = 7; |
| 80 | printk("Loglevel set to %d\n", i); |
| 81 | console_loglevel = i; |
| 82 | } |
| 83 | static struct sysrq_key_op sysrq_loglevel_op = { |
| 84 | .handler = sysrq_handle_loglevel, |
| 85 | .help_msg = "loglevel(0-9)", |
| 86 | .action_msg = "Changing Loglevel", |
| 87 | .enable_mask = SYSRQ_ENABLE_LOG, |
| 88 | }; |
| 89 | |
| 90 | #ifdef CONFIG_VT |
| 91 | static void sysrq_handle_SAK(int key, struct tty_struct *tty) |
| 92 | { |
| 93 | struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work; |
| 94 | schedule_work(SAK_work); |
| 95 | } |
| 96 | static struct sysrq_key_op sysrq_SAK_op = { |
| 97 | .handler = sysrq_handle_SAK, |
| 98 | .help_msg = "saK", |
| 99 | .action_msg = "SAK", |
| 100 | .enable_mask = SYSRQ_ENABLE_KEYBOARD, |
| 101 | }; |
| 102 | #else |
| 103 | #define sysrq_SAK_op (*(struct sysrq_key_op *)0) |
| 104 | #endif |
| 105 | |
| 106 | #ifdef CONFIG_VT |
| 107 | static void sysrq_handle_unraw(int key, struct tty_struct *tty) |
| 108 | { |
| 109 | struct kbd_struct *kbd = &kbd_table[fg_console]; |
| 110 | |
| 111 | if (kbd) |
| 112 | kbd->kbdmode = default_utf8 ? VC_UNICODE : VC_XLATE; |
| 113 | } |
| 114 | static struct sysrq_key_op sysrq_unraw_op = { |
| 115 | .handler = sysrq_handle_unraw, |
| 116 | .help_msg = "unRaw", |
| 117 | .action_msg = "Keyboard mode set to system default", |
| 118 | .enable_mask = SYSRQ_ENABLE_KEYBOARD, |
| 119 | }; |
| 120 | #else |
| 121 | #define sysrq_unraw_op (*(struct sysrq_key_op *)0) |
| 122 | #endif /* CONFIG_VT */ |
| 123 | |
| 124 | static void sysrq_handle_crash(int key, struct tty_struct *tty) |
| 125 | { |
| 126 | char *killer = NULL; |
| 127 | *killer = 1; |
| 128 | } |
| 129 | static struct sysrq_key_op sysrq_crashdump_op = { |
| 130 | .handler = sysrq_handle_crash, |
| 131 | .help_msg = "Crash", |
| 132 | .action_msg = "Trigger a crash", |
| 133 | .enable_mask = SYSRQ_ENABLE_DUMP, |
| 134 | }; |
| 135 | |
| 136 | static void sysrq_handle_reboot(int key, struct tty_struct *tty) |
| 137 | { |
| 138 | lockdep_off(); |
| 139 | local_irq_enable(); |
| 140 | emergency_restart(); |
| 141 | } |
| 142 | static struct sysrq_key_op sysrq_reboot_op = { |
| 143 | .handler = sysrq_handle_reboot, |
| 144 | .help_msg = "reBoot", |
| 145 | .action_msg = "Resetting", |
| 146 | .enable_mask = SYSRQ_ENABLE_BOOT, |
| 147 | }; |
| 148 | |
| 149 | static void sysrq_handle_sync(int key, struct tty_struct *tty) |
| 150 | { |
| 151 | emergency_sync(); |
| 152 | } |
| 153 | static struct sysrq_key_op sysrq_sync_op = { |
| 154 | .handler = sysrq_handle_sync, |
| 155 | .help_msg = "Sync", |
| 156 | .action_msg = "Emergency Sync", |
| 157 | .enable_mask = SYSRQ_ENABLE_SYNC, |
| 158 | }; |
| 159 | |
| 160 | static void sysrq_handle_show_timers(int key, struct tty_struct *tty) |
| 161 | { |
| 162 | sysrq_timer_list_show(); |
| 163 | } |
| 164 | |
| 165 | static struct sysrq_key_op sysrq_show_timers_op = { |
| 166 | .handler = sysrq_handle_show_timers, |
| 167 | .help_msg = "show-all-timers(Q)", |
| 168 | .action_msg = "Show clockevent devices & pending hrtimers (no others)", |
| 169 | }; |
| 170 | |
| 171 | static void sysrq_handle_mountro(int key, struct tty_struct *tty) |
| 172 | { |
| 173 | emergency_remount(); |
| 174 | } |
| 175 | static struct sysrq_key_op sysrq_mountro_op = { |
| 176 | .handler = sysrq_handle_mountro, |
| 177 | .help_msg = "Unmount", |
| 178 | .action_msg = "Emergency Remount R/O", |
| 179 | .enable_mask = SYSRQ_ENABLE_REMOUNT, |
| 180 | }; |
| 181 | |
| 182 | #ifdef CONFIG_LOCKDEP |
| 183 | static void sysrq_handle_showlocks(int key, struct tty_struct *tty) |
| 184 | { |
| 185 | debug_show_all_locks(); |
| 186 | } |
| 187 | |
| 188 | static struct sysrq_key_op sysrq_showlocks_op = { |
| 189 | .handler = sysrq_handle_showlocks, |
| 190 | .help_msg = "show-all-locks(D)", |
| 191 | .action_msg = "Show Locks Held", |
| 192 | }; |
| 193 | #else |
| 194 | #define sysrq_showlocks_op (*(struct sysrq_key_op *)0) |
| 195 | #endif |
| 196 | |
| 197 | #ifdef CONFIG_SMP |
| 198 | static DEFINE_SPINLOCK(show_lock); |
| 199 | |
| 200 | static void showacpu(void *dummy) |
| 201 | { |
| 202 | unsigned long flags; |
| 203 | |
| 204 | /* Idle CPUs have no interesting backtrace. */ |
| 205 | if (idle_cpu(smp_processor_id())) |
| 206 | return; |
| 207 | |
| 208 | spin_lock_irqsave(&show_lock, flags); |
| 209 | printk(KERN_INFO "CPU%d:\n", smp_processor_id()); |
| 210 | show_stack(NULL, NULL); |
| 211 | spin_unlock_irqrestore(&show_lock, flags); |
| 212 | } |
| 213 | |
| 214 | static void sysrq_showregs_othercpus(struct work_struct *dummy) |
| 215 | { |
| 216 | smp_call_function(showacpu, NULL, 0); |
| 217 | } |
| 218 | |
| 219 | static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus); |
| 220 | |
| 221 | static void sysrq_handle_showallcpus(int key, struct tty_struct *tty) |
| 222 | { |
| 223 | struct pt_regs *regs = get_irq_regs(); |
| 224 | if (regs) { |
| 225 | printk(KERN_INFO "CPU%d:\n", smp_processor_id()); |
| 226 | show_regs(regs); |
| 227 | } |
| 228 | schedule_work(&sysrq_showallcpus); |
| 229 | } |
| 230 | |
| 231 | static struct sysrq_key_op sysrq_showallcpus_op = { |
| 232 | .handler = sysrq_handle_showallcpus, |
| 233 | .help_msg = "show-backtrace-all-active-cpus(L)", |
| 234 | .action_msg = "Show backtrace of all active CPUs", |
| 235 | .enable_mask = SYSRQ_ENABLE_DUMP, |
| 236 | }; |
| 237 | #endif |
| 238 | |
| 239 | static void sysrq_handle_showregs(int key, struct tty_struct *tty) |
| 240 | { |
| 241 | struct pt_regs *regs = get_irq_regs(); |
| 242 | if (regs) |
| 243 | show_regs(regs); |
| 244 | perf_counter_print_debug(); |
| 245 | } |
| 246 | static struct sysrq_key_op sysrq_showregs_op = { |
| 247 | .handler = sysrq_handle_showregs, |
| 248 | .help_msg = "show-registers(P)", |
| 249 | .action_msg = "Show Regs", |
| 250 | .enable_mask = SYSRQ_ENABLE_DUMP, |
| 251 | }; |
| 252 | |
| 253 | static void sysrq_handle_showstate(int key, struct tty_struct *tty) |
| 254 | { |
| 255 | show_state(); |
| 256 | } |
| 257 | static struct sysrq_key_op sysrq_showstate_op = { |
| 258 | .handler = sysrq_handle_showstate, |
| 259 | .help_msg = "show-task-states(T)", |
| 260 | .action_msg = "Show State", |
| 261 | .enable_mask = SYSRQ_ENABLE_DUMP, |
| 262 | }; |
| 263 | |
| 264 | static void sysrq_handle_showstate_blocked(int key, struct tty_struct *tty) |
| 265 | { |
| 266 | show_state_filter(TASK_UNINTERRUPTIBLE); |
| 267 | } |
| 268 | static struct sysrq_key_op sysrq_showstate_blocked_op = { |
| 269 | .handler = sysrq_handle_showstate_blocked, |
| 270 | .help_msg = "show-blocked-tasks(W)", |
| 271 | .action_msg = "Show Blocked State", |
| 272 | .enable_mask = SYSRQ_ENABLE_DUMP, |
| 273 | }; |
| 274 | |
| 275 | #ifdef CONFIG_TRACING |
| 276 | #include <linux/ftrace.h> |
| 277 | |
| 278 | static void sysrq_ftrace_dump(int key, struct tty_struct *tty) |
| 279 | { |
| 280 | ftrace_dump(); |
| 281 | } |
| 282 | static struct sysrq_key_op sysrq_ftrace_dump_op = { |
| 283 | .handler = sysrq_ftrace_dump, |
| 284 | .help_msg = "dump-ftrace-buffer(Z)", |
| 285 | .action_msg = "Dump ftrace buffer", |
| 286 | .enable_mask = SYSRQ_ENABLE_DUMP, |
| 287 | }; |
| 288 | #else |
| 289 | #define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)0) |
| 290 | #endif |
| 291 | |
| 292 | static void sysrq_handle_showmem(int key, struct tty_struct *tty) |
| 293 | { |
| 294 | show_mem(); |
| 295 | } |
| 296 | static struct sysrq_key_op sysrq_showmem_op = { |
| 297 | .handler = sysrq_handle_showmem, |
| 298 | .help_msg = "show-memory-usage(M)", |
| 299 | .action_msg = "Show Memory", |
| 300 | .enable_mask = SYSRQ_ENABLE_DUMP, |
| 301 | }; |
| 302 | |
| 303 | /* |
| 304 | * Signal sysrq helper function. Sends a signal to all user processes. |
| 305 | */ |
| 306 | static void send_sig_all(int sig) |
| 307 | { |
| 308 | struct task_struct *p; |
| 309 | |
| 310 | for_each_process(p) { |
| 311 | if (p->mm && !is_global_init(p)) |
| 312 | /* Not swapper, init nor kernel thread */ |
| 313 | force_sig(sig, p); |
| 314 | } |
| 315 | } |
| 316 | |
| 317 | static void sysrq_handle_term(int key, struct tty_struct *tty) |
| 318 | { |
| 319 | send_sig_all(SIGTERM); |
| 320 | console_loglevel = 8; |
| 321 | } |
| 322 | static struct sysrq_key_op sysrq_term_op = { |
| 323 | .handler = sysrq_handle_term, |
| 324 | .help_msg = "terminate-all-tasks(E)", |
| 325 | .action_msg = "Terminate All Tasks", |
| 326 | .enable_mask = SYSRQ_ENABLE_SIGNAL, |
| 327 | }; |
| 328 | |
| 329 | static void moom_callback(struct work_struct *ignored) |
| 330 | { |
| 331 | out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0); |
| 332 | } |
| 333 | |
| 334 | static DECLARE_WORK(moom_work, moom_callback); |
| 335 | |
| 336 | static void sysrq_handle_moom(int key, struct tty_struct *tty) |
| 337 | { |
| 338 | schedule_work(&moom_work); |
| 339 | } |
| 340 | static struct sysrq_key_op sysrq_moom_op = { |
| 341 | .handler = sysrq_handle_moom, |
| 342 | .help_msg = "memory-full-oom-kill(F)", |
| 343 | .action_msg = "Manual OOM execution", |
| 344 | .enable_mask = SYSRQ_ENABLE_SIGNAL, |
| 345 | }; |
| 346 | |
| 347 | #ifdef CONFIG_BLOCK |
| 348 | static void sysrq_handle_thaw(int key, struct tty_struct *tty) |
| 349 | { |
| 350 | emergency_thaw_all(); |
| 351 | } |
| 352 | static struct sysrq_key_op sysrq_thaw_op = { |
| 353 | .handler = sysrq_handle_thaw, |
| 354 | .help_msg = "thaw-filesystems(J)", |
| 355 | .action_msg = "Emergency Thaw of all frozen filesystems", |
| 356 | .enable_mask = SYSRQ_ENABLE_SIGNAL, |
| 357 | }; |
| 358 | #endif |
| 359 | |
| 360 | static void sysrq_handle_kill(int key, struct tty_struct *tty) |
| 361 | { |
| 362 | send_sig_all(SIGKILL); |
| 363 | console_loglevel = 8; |
| 364 | } |
| 365 | static struct sysrq_key_op sysrq_kill_op = { |
| 366 | .handler = sysrq_handle_kill, |
| 367 | .help_msg = "kill-all-tasks(I)", |
| 368 | .action_msg = "Kill All Tasks", |
| 369 | .enable_mask = SYSRQ_ENABLE_SIGNAL, |
| 370 | }; |
| 371 | |
| 372 | static void sysrq_handle_unrt(int key, struct tty_struct *tty) |
| 373 | { |
| 374 | normalize_rt_tasks(); |
| 375 | } |
| 376 | static struct sysrq_key_op sysrq_unrt_op = { |
| 377 | .handler = sysrq_handle_unrt, |
| 378 | .help_msg = "nice-all-RT-tasks(N)", |
| 379 | .action_msg = "Nice All RT Tasks", |
| 380 | .enable_mask = SYSRQ_ENABLE_RTNICE, |
| 381 | }; |
| 382 | |
| 383 | /* Key Operations table and lock */ |
| 384 | static DEFINE_SPINLOCK(sysrq_key_table_lock); |
| 385 | |
| 386 | static struct sysrq_key_op *sysrq_key_table[36] = { |
| 387 | &sysrq_loglevel_op, /* 0 */ |
| 388 | &sysrq_loglevel_op, /* 1 */ |
| 389 | &sysrq_loglevel_op, /* 2 */ |
| 390 | &sysrq_loglevel_op, /* 3 */ |
| 391 | &sysrq_loglevel_op, /* 4 */ |
| 392 | &sysrq_loglevel_op, /* 5 */ |
| 393 | &sysrq_loglevel_op, /* 6 */ |
| 394 | &sysrq_loglevel_op, /* 7 */ |
| 395 | &sysrq_loglevel_op, /* 8 */ |
| 396 | &sysrq_loglevel_op, /* 9 */ |
| 397 | |
| 398 | /* |
| 399 | * a: Don't use for system provided sysrqs, it is handled specially on |
| 400 | * sparc and will never arrive. |
| 401 | */ |
| 402 | NULL, /* a */ |
| 403 | &sysrq_reboot_op, /* b */ |
| 404 | &sysrq_crashdump_op, /* c & ibm_emac driver debug */ |
| 405 | &sysrq_showlocks_op, /* d */ |
| 406 | &sysrq_term_op, /* e */ |
| 407 | &sysrq_moom_op, /* f */ |
| 408 | /* g: May be registered for the kernel debugger */ |
| 409 | NULL, /* g */ |
| 410 | NULL, /* h - reserved for help */ |
| 411 | &sysrq_kill_op, /* i */ |
| 412 | #ifdef CONFIG_BLOCK |
| 413 | &sysrq_thaw_op, /* j */ |
| 414 | #else |
| 415 | NULL, /* j */ |
| 416 | #endif |
| 417 | &sysrq_SAK_op, /* k */ |
| 418 | #ifdef CONFIG_SMP |
| 419 | &sysrq_showallcpus_op, /* l */ |
| 420 | #else |
| 421 | NULL, /* l */ |
| 422 | #endif |
| 423 | &sysrq_showmem_op, /* m */ |
| 424 | &sysrq_unrt_op, /* n */ |
| 425 | /* o: This will often be registered as 'Off' at init time */ |
| 426 | NULL, /* o */ |
| 427 | &sysrq_showregs_op, /* p */ |
| 428 | &sysrq_show_timers_op, /* q */ |
| 429 | &sysrq_unraw_op, /* r */ |
| 430 | &sysrq_sync_op, /* s */ |
| 431 | &sysrq_showstate_op, /* t */ |
| 432 | &sysrq_mountro_op, /* u */ |
| 433 | /* v: May be registered for frame buffer console restore */ |
| 434 | NULL, /* v */ |
| 435 | &sysrq_showstate_blocked_op, /* w */ |
| 436 | /* x: May be registered on ppc/powerpc for xmon */ |
| 437 | NULL, /* x */ |
| 438 | /* y: May be registered on sparc64 for global register dump */ |
| 439 | NULL, /* y */ |
| 440 | &sysrq_ftrace_dump_op, /* z */ |
| 441 | }; |
| 442 | |
| 443 | /* key2index calculation, -1 on invalid index */ |
| 444 | static int sysrq_key_table_key2index(int key) |
| 445 | { |
| 446 | int retval; |
| 447 | |
| 448 | if ((key >= '0') && (key <= '9')) |
| 449 | retval = key - '0'; |
| 450 | else if ((key >= 'a') && (key <= 'z')) |
| 451 | retval = key + 10 - 'a'; |
| 452 | else |
| 453 | retval = -1; |
| 454 | return retval; |
| 455 | } |
| 456 | |
| 457 | /* |
| 458 | * get and put functions for the table, exposed to modules. |
| 459 | */ |
| 460 | struct sysrq_key_op *__sysrq_get_key_op(int key) |
| 461 | { |
| 462 | struct sysrq_key_op *op_p = NULL; |
| 463 | int i; |
| 464 | |
| 465 | i = sysrq_key_table_key2index(key); |
| 466 | if (i != -1) |
| 467 | op_p = sysrq_key_table[i]; |
| 468 | return op_p; |
| 469 | } |
| 470 | |
| 471 | static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p) |
| 472 | { |
| 473 | int i = sysrq_key_table_key2index(key); |
| 474 | |
| 475 | if (i != -1) |
| 476 | sysrq_key_table[i] = op_p; |
| 477 | } |
| 478 | |
| 479 | /* |
| 480 | * This is the non-locking version of handle_sysrq. It must/can only be called |
| 481 | * by sysrq key handlers, as they are inside of the lock |
| 482 | */ |
| 483 | void __handle_sysrq(int key, struct tty_struct *tty, int check_mask) |
| 484 | { |
| 485 | struct sysrq_key_op *op_p; |
| 486 | int orig_log_level; |
| 487 | int i; |
| 488 | unsigned long flags; |
| 489 | |
| 490 | spin_lock_irqsave(&sysrq_key_table_lock, flags); |
| 491 | /* |
| 492 | * Raise the apparent loglevel to maximum so that the sysrq header |
| 493 | * is shown to provide the user with positive feedback. We do not |
| 494 | * simply emit this at KERN_EMERG as that would change message |
| 495 | * routing in the consumers of /proc/kmsg. |
| 496 | */ |
| 497 | orig_log_level = console_loglevel; |
| 498 | console_loglevel = 7; |
| 499 | printk(KERN_INFO "SysRq : "); |
| 500 | |
| 501 | op_p = __sysrq_get_key_op(key); |
| 502 | if (op_p) { |
| 503 | /* |
| 504 | * Should we check for enabled operations (/proc/sysrq-trigger |
| 505 | * should not) and is the invoked operation enabled? |
| 506 | */ |
| 507 | if (!check_mask || sysrq_on_mask(op_p->enable_mask)) { |
| 508 | printk("%s\n", op_p->action_msg); |
| 509 | console_loglevel = orig_log_level; |
| 510 | op_p->handler(key, tty); |
| 511 | } else { |
| 512 | printk("This sysrq operation is disabled.\n"); |
| 513 | } |
| 514 | } else { |
| 515 | printk("HELP : "); |
| 516 | /* Only print the help msg once per handler */ |
| 517 | for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) { |
| 518 | if (sysrq_key_table[i]) { |
| 519 | int j; |
| 520 | |
| 521 | for (j = 0; sysrq_key_table[i] != |
| 522 | sysrq_key_table[j]; j++) |
| 523 | ; |
| 524 | if (j != i) |
| 525 | continue; |
| 526 | printk("%s ", sysrq_key_table[i]->help_msg); |
| 527 | } |
| 528 | } |
| 529 | printk("\n"); |
| 530 | console_loglevel = orig_log_level; |
| 531 | } |
| 532 | spin_unlock_irqrestore(&sysrq_key_table_lock, flags); |
| 533 | } |
| 534 | |
| 535 | /* |
| 536 | * This function is called by the keyboard handler when SysRq is pressed |
| 537 | * and any other keycode arrives. |
| 538 | */ |
| 539 | void handle_sysrq(int key, struct tty_struct *tty) |
| 540 | { |
| 541 | if (sysrq_on()) |
| 542 | __handle_sysrq(key, tty, 1); |
| 543 | } |
| 544 | EXPORT_SYMBOL(handle_sysrq); |
| 545 | |
| 546 | static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p, |
| 547 | struct sysrq_key_op *remove_op_p) |
| 548 | { |
| 549 | |
| 550 | int retval; |
| 551 | unsigned long flags; |
| 552 | |
| 553 | spin_lock_irqsave(&sysrq_key_table_lock, flags); |
| 554 | if (__sysrq_get_key_op(key) == remove_op_p) { |
| 555 | __sysrq_put_key_op(key, insert_op_p); |
| 556 | retval = 0; |
| 557 | } else { |
| 558 | retval = -1; |
| 559 | } |
| 560 | spin_unlock_irqrestore(&sysrq_key_table_lock, flags); |
| 561 | return retval; |
| 562 | } |
| 563 | |
| 564 | int register_sysrq_key(int key, struct sysrq_key_op *op_p) |
| 565 | { |
| 566 | return __sysrq_swap_key_ops(key, op_p, NULL); |
| 567 | } |
| 568 | EXPORT_SYMBOL(register_sysrq_key); |
| 569 | |
| 570 | int unregister_sysrq_key(int key, struct sysrq_key_op *op_p) |
| 571 | { |
| 572 | return __sysrq_swap_key_ops(key, NULL, op_p); |
| 573 | } |
| 574 | EXPORT_SYMBOL(unregister_sysrq_key); |
| 575 | |
| 576 | #ifdef CONFIG_PROC_FS |
| 577 | /* |
| 578 | * writing 'C' to /proc/sysrq-trigger is like sysrq-C |
| 579 | */ |
| 580 | static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf, |
| 581 | size_t count, loff_t *ppos) |
| 582 | { |
| 583 | if (count) { |
| 584 | char c; |
| 585 | |
| 586 | if (get_user(c, buf)) |
| 587 | return -EFAULT; |
| 588 | __handle_sysrq(c, NULL, 0); |
| 589 | } |
| 590 | return count; |
| 591 | } |
| 592 | |
| 593 | static const struct file_operations proc_sysrq_trigger_operations = { |
| 594 | .write = write_sysrq_trigger, |
| 595 | }; |
| 596 | |
| 597 | static int __init sysrq_init(void) |
| 598 | { |
| 599 | proc_create("sysrq-trigger", S_IWUSR, NULL, &proc_sysrq_trigger_operations); |
| 600 | return 0; |
| 601 | } |
| 602 | module_init(sysrq_init); |
| 603 | #endif |