| 1 | /* |
| 2 | * Linux Magic System Request Key Hacks |
| 3 | * |
| 4 | * (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz> |
| 5 | * based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz> |
| 6 | * |
| 7 | * (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com> |
| 8 | * overhauled to use key registration |
| 9 | * based upon discusions in irc://irc.openprojects.net/#kernelnewbies |
| 10 | * |
| 11 | * Copyright (c) 2010 Dmitry Torokhov |
| 12 | * Input handler conversion |
| 13 | */ |
| 14 | |
| 15 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| 16 | |
| 17 | #include <linux/sched.h> |
| 18 | #include <linux/interrupt.h> |
| 19 | #include <linux/mm.h> |
| 20 | #include <linux/fs.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/proc_fs.h> |
| 28 | #include <linux/nmi.h> |
| 29 | #include <linux/quotaops.h> |
| 30 | #include <linux/perf_event.h> |
| 31 | #include <linux/kernel.h> |
| 32 | #include <linux/module.h> |
| 33 | #include <linux/suspend.h> |
| 34 | #include <linux/writeback.h> |
| 35 | #include <linux/buffer_head.h> /* for fsync_bdev() */ |
| 36 | #include <linux/swap.h> |
| 37 | #include <linux/spinlock.h> |
| 38 | #include <linux/vt_kern.h> |
| 39 | #include <linux/workqueue.h> |
| 40 | #include <linux/hrtimer.h> |
| 41 | #include <linux/oom.h> |
| 42 | #include <linux/slab.h> |
| 43 | #include <linux/input.h> |
| 44 | |
| 45 | #include <asm/ptrace.h> |
| 46 | #include <asm/irq_regs.h> |
| 47 | |
| 48 | /* Whether we react on sysrq keys or just ignore them */ |
| 49 | static int __read_mostly sysrq_enabled = SYSRQ_DEFAULT_ENABLE; |
| 50 | static bool __read_mostly sysrq_always_enabled; |
| 51 | |
| 52 | static bool sysrq_on(void) |
| 53 | { |
| 54 | return sysrq_enabled || sysrq_always_enabled; |
| 55 | } |
| 56 | |
| 57 | /* |
| 58 | * A value of 1 means 'all', other nonzero values are an op mask: |
| 59 | */ |
| 60 | static bool sysrq_on_mask(int mask) |
| 61 | { |
| 62 | return sysrq_always_enabled || |
| 63 | sysrq_enabled == 1 || |
| 64 | (sysrq_enabled & mask); |
| 65 | } |
| 66 | |
| 67 | static int __init sysrq_always_enabled_setup(char *str) |
| 68 | { |
| 69 | sysrq_always_enabled = true; |
| 70 | pr_info("sysrq always enabled.\n"); |
| 71 | |
| 72 | return 1; |
| 73 | } |
| 74 | |
| 75 | __setup("sysrq_always_enabled", sysrq_always_enabled_setup); |
| 76 | |
| 77 | |
| 78 | static void sysrq_handle_loglevel(int key) |
| 79 | { |
| 80 | int i; |
| 81 | |
| 82 | i = key - '0'; |
| 83 | console_loglevel = 7; |
| 84 | printk("Loglevel set to %d\n", i); |
| 85 | console_loglevel = i; |
| 86 | } |
| 87 | static struct sysrq_key_op sysrq_loglevel_op = { |
| 88 | .handler = sysrq_handle_loglevel, |
| 89 | .help_msg = "loglevel(0-9)", |
| 90 | .action_msg = "Changing Loglevel", |
| 91 | .enable_mask = SYSRQ_ENABLE_LOG, |
| 92 | }; |
| 93 | |
| 94 | #ifdef CONFIG_VT |
| 95 | static void sysrq_handle_SAK(int key) |
| 96 | { |
| 97 | struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work; |
| 98 | schedule_work(SAK_work); |
| 99 | } |
| 100 | static struct sysrq_key_op sysrq_SAK_op = { |
| 101 | .handler = sysrq_handle_SAK, |
| 102 | .help_msg = "saK", |
| 103 | .action_msg = "SAK", |
| 104 | .enable_mask = SYSRQ_ENABLE_KEYBOARD, |
| 105 | }; |
| 106 | #else |
| 107 | #define sysrq_SAK_op (*(struct sysrq_key_op *)NULL) |
| 108 | #endif |
| 109 | |
| 110 | #ifdef CONFIG_VT |
| 111 | static void sysrq_handle_unraw(int key) |
| 112 | { |
| 113 | struct kbd_struct *kbd = &kbd_table[fg_console]; |
| 114 | |
| 115 | if (kbd) |
| 116 | kbd->kbdmode = default_utf8 ? VC_UNICODE : VC_XLATE; |
| 117 | } |
| 118 | static struct sysrq_key_op sysrq_unraw_op = { |
| 119 | .handler = sysrq_handle_unraw, |
| 120 | .help_msg = "unRaw", |
| 121 | .action_msg = "Keyboard mode set to system default", |
| 122 | .enable_mask = SYSRQ_ENABLE_KEYBOARD, |
| 123 | }; |
| 124 | #else |
| 125 | #define sysrq_unraw_op (*(struct sysrq_key_op *)NULL) |
| 126 | #endif /* CONFIG_VT */ |
| 127 | |
| 128 | static void sysrq_handle_crash(int key) |
| 129 | { |
| 130 | char *killer = NULL; |
| 131 | |
| 132 | panic_on_oops = 1; /* force panic */ |
| 133 | wmb(); |
| 134 | *killer = 1; |
| 135 | } |
| 136 | static struct sysrq_key_op sysrq_crash_op = { |
| 137 | .handler = sysrq_handle_crash, |
| 138 | .help_msg = "Crash", |
| 139 | .action_msg = "Trigger a crash", |
| 140 | .enable_mask = SYSRQ_ENABLE_DUMP, |
| 141 | }; |
| 142 | |
| 143 | static void sysrq_handle_reboot(int key) |
| 144 | { |
| 145 | lockdep_off(); |
| 146 | local_irq_enable(); |
| 147 | emergency_restart(); |
| 148 | } |
| 149 | static struct sysrq_key_op sysrq_reboot_op = { |
| 150 | .handler = sysrq_handle_reboot, |
| 151 | .help_msg = "reBoot", |
| 152 | .action_msg = "Resetting", |
| 153 | .enable_mask = SYSRQ_ENABLE_BOOT, |
| 154 | }; |
| 155 | |
| 156 | static void sysrq_handle_sync(int key) |
| 157 | { |
| 158 | emergency_sync(); |
| 159 | } |
| 160 | static struct sysrq_key_op sysrq_sync_op = { |
| 161 | .handler = sysrq_handle_sync, |
| 162 | .help_msg = "Sync", |
| 163 | .action_msg = "Emergency Sync", |
| 164 | .enable_mask = SYSRQ_ENABLE_SYNC, |
| 165 | }; |
| 166 | |
| 167 | static void sysrq_handle_show_timers(int key) |
| 168 | { |
| 169 | sysrq_timer_list_show(); |
| 170 | } |
| 171 | |
| 172 | static struct sysrq_key_op sysrq_show_timers_op = { |
| 173 | .handler = sysrq_handle_show_timers, |
| 174 | .help_msg = "show-all-timers(Q)", |
| 175 | .action_msg = "Show clockevent devices & pending hrtimers (no others)", |
| 176 | }; |
| 177 | |
| 178 | static void sysrq_handle_mountro(int key) |
| 179 | { |
| 180 | emergency_remount(); |
| 181 | } |
| 182 | static struct sysrq_key_op sysrq_mountro_op = { |
| 183 | .handler = sysrq_handle_mountro, |
| 184 | .help_msg = "Unmount", |
| 185 | .action_msg = "Emergency Remount R/O", |
| 186 | .enable_mask = SYSRQ_ENABLE_REMOUNT, |
| 187 | }; |
| 188 | |
| 189 | #ifdef CONFIG_LOCKDEP |
| 190 | static void sysrq_handle_showlocks(int key) |
| 191 | { |
| 192 | debug_show_all_locks(); |
| 193 | } |
| 194 | |
| 195 | static struct sysrq_key_op sysrq_showlocks_op = { |
| 196 | .handler = sysrq_handle_showlocks, |
| 197 | .help_msg = "show-all-locks(D)", |
| 198 | .action_msg = "Show Locks Held", |
| 199 | }; |
| 200 | #else |
| 201 | #define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL) |
| 202 | #endif |
| 203 | |
| 204 | #ifdef CONFIG_SMP |
| 205 | static DEFINE_SPINLOCK(show_lock); |
| 206 | |
| 207 | static void showacpu(void *dummy) |
| 208 | { |
| 209 | unsigned long flags; |
| 210 | |
| 211 | /* Idle CPUs have no interesting backtrace. */ |
| 212 | if (idle_cpu(smp_processor_id())) |
| 213 | return; |
| 214 | |
| 215 | spin_lock_irqsave(&show_lock, flags); |
| 216 | printk(KERN_INFO "CPU%d:\n", smp_processor_id()); |
| 217 | show_stack(NULL, NULL); |
| 218 | spin_unlock_irqrestore(&show_lock, flags); |
| 219 | } |
| 220 | |
| 221 | static void sysrq_showregs_othercpus(struct work_struct *dummy) |
| 222 | { |
| 223 | smp_call_function(showacpu, NULL, 0); |
| 224 | } |
| 225 | |
| 226 | static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus); |
| 227 | |
| 228 | static void sysrq_handle_showallcpus(int key) |
| 229 | { |
| 230 | /* |
| 231 | * Fall back to the workqueue based printing if the |
| 232 | * backtrace printing did not succeed or the |
| 233 | * architecture has no support for it: |
| 234 | */ |
| 235 | if (!trigger_all_cpu_backtrace()) { |
| 236 | struct pt_regs *regs = get_irq_regs(); |
| 237 | |
| 238 | if (regs) { |
| 239 | printk(KERN_INFO "CPU%d:\n", smp_processor_id()); |
| 240 | show_regs(regs); |
| 241 | } |
| 242 | schedule_work(&sysrq_showallcpus); |
| 243 | } |
| 244 | } |
| 245 | |
| 246 | static struct sysrq_key_op sysrq_showallcpus_op = { |
| 247 | .handler = sysrq_handle_showallcpus, |
| 248 | .help_msg = "show-backtrace-all-active-cpus(L)", |
| 249 | .action_msg = "Show backtrace of all active CPUs", |
| 250 | .enable_mask = SYSRQ_ENABLE_DUMP, |
| 251 | }; |
| 252 | #endif |
| 253 | |
| 254 | static void sysrq_handle_showregs(int key) |
| 255 | { |
| 256 | struct pt_regs *regs = get_irq_regs(); |
| 257 | if (regs) |
| 258 | show_regs(regs); |
| 259 | perf_event_print_debug(); |
| 260 | } |
| 261 | static struct sysrq_key_op sysrq_showregs_op = { |
| 262 | .handler = sysrq_handle_showregs, |
| 263 | .help_msg = "show-registers(P)", |
| 264 | .action_msg = "Show Regs", |
| 265 | .enable_mask = SYSRQ_ENABLE_DUMP, |
| 266 | }; |
| 267 | |
| 268 | static void sysrq_handle_showstate(int key) |
| 269 | { |
| 270 | show_state(); |
| 271 | } |
| 272 | static struct sysrq_key_op sysrq_showstate_op = { |
| 273 | .handler = sysrq_handle_showstate, |
| 274 | .help_msg = "show-task-states(T)", |
| 275 | .action_msg = "Show State", |
| 276 | .enable_mask = SYSRQ_ENABLE_DUMP, |
| 277 | }; |
| 278 | |
| 279 | static void sysrq_handle_showstate_blocked(int key) |
| 280 | { |
| 281 | show_state_filter(TASK_UNINTERRUPTIBLE); |
| 282 | } |
| 283 | static struct sysrq_key_op sysrq_showstate_blocked_op = { |
| 284 | .handler = sysrq_handle_showstate_blocked, |
| 285 | .help_msg = "show-blocked-tasks(W)", |
| 286 | .action_msg = "Show Blocked State", |
| 287 | .enable_mask = SYSRQ_ENABLE_DUMP, |
| 288 | }; |
| 289 | |
| 290 | #ifdef CONFIG_TRACING |
| 291 | #include <linux/ftrace.h> |
| 292 | |
| 293 | static void sysrq_ftrace_dump(int key) |
| 294 | { |
| 295 | ftrace_dump(DUMP_ALL); |
| 296 | } |
| 297 | static struct sysrq_key_op sysrq_ftrace_dump_op = { |
| 298 | .handler = sysrq_ftrace_dump, |
| 299 | .help_msg = "dump-ftrace-buffer(Z)", |
| 300 | .action_msg = "Dump ftrace buffer", |
| 301 | .enable_mask = SYSRQ_ENABLE_DUMP, |
| 302 | }; |
| 303 | #else |
| 304 | #define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL) |
| 305 | #endif |
| 306 | |
| 307 | static void sysrq_handle_showmem(int key) |
| 308 | { |
| 309 | show_mem(); |
| 310 | } |
| 311 | static struct sysrq_key_op sysrq_showmem_op = { |
| 312 | .handler = sysrq_handle_showmem, |
| 313 | .help_msg = "show-memory-usage(M)", |
| 314 | .action_msg = "Show Memory", |
| 315 | .enable_mask = SYSRQ_ENABLE_DUMP, |
| 316 | }; |
| 317 | |
| 318 | /* |
| 319 | * Signal sysrq helper function. Sends a signal to all user processes. |
| 320 | */ |
| 321 | static void send_sig_all(int sig) |
| 322 | { |
| 323 | struct task_struct *p; |
| 324 | |
| 325 | for_each_process(p) { |
| 326 | if (p->mm && !is_global_init(p)) |
| 327 | /* Not swapper, init nor kernel thread */ |
| 328 | force_sig(sig, p); |
| 329 | } |
| 330 | } |
| 331 | |
| 332 | static void sysrq_handle_term(int key) |
| 333 | { |
| 334 | send_sig_all(SIGTERM); |
| 335 | console_loglevel = 8; |
| 336 | } |
| 337 | static struct sysrq_key_op sysrq_term_op = { |
| 338 | .handler = sysrq_handle_term, |
| 339 | .help_msg = "terminate-all-tasks(E)", |
| 340 | .action_msg = "Terminate All Tasks", |
| 341 | .enable_mask = SYSRQ_ENABLE_SIGNAL, |
| 342 | }; |
| 343 | |
| 344 | static void moom_callback(struct work_struct *ignored) |
| 345 | { |
| 346 | out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0, NULL); |
| 347 | } |
| 348 | |
| 349 | static DECLARE_WORK(moom_work, moom_callback); |
| 350 | |
| 351 | static void sysrq_handle_moom(int key) |
| 352 | { |
| 353 | schedule_work(&moom_work); |
| 354 | } |
| 355 | static struct sysrq_key_op sysrq_moom_op = { |
| 356 | .handler = sysrq_handle_moom, |
| 357 | .help_msg = "memory-full-oom-kill(F)", |
| 358 | .action_msg = "Manual OOM execution", |
| 359 | .enable_mask = SYSRQ_ENABLE_SIGNAL, |
| 360 | }; |
| 361 | |
| 362 | #ifdef CONFIG_BLOCK |
| 363 | static void sysrq_handle_thaw(int key) |
| 364 | { |
| 365 | emergency_thaw_all(); |
| 366 | } |
| 367 | static struct sysrq_key_op sysrq_thaw_op = { |
| 368 | .handler = sysrq_handle_thaw, |
| 369 | .help_msg = "thaw-filesystems(J)", |
| 370 | .action_msg = "Emergency Thaw of all frozen filesystems", |
| 371 | .enable_mask = SYSRQ_ENABLE_SIGNAL, |
| 372 | }; |
| 373 | #endif |
| 374 | |
| 375 | static void sysrq_handle_kill(int key) |
| 376 | { |
| 377 | send_sig_all(SIGKILL); |
| 378 | console_loglevel = 8; |
| 379 | } |
| 380 | static struct sysrq_key_op sysrq_kill_op = { |
| 381 | .handler = sysrq_handle_kill, |
| 382 | .help_msg = "kill-all-tasks(I)", |
| 383 | .action_msg = "Kill All Tasks", |
| 384 | .enable_mask = SYSRQ_ENABLE_SIGNAL, |
| 385 | }; |
| 386 | |
| 387 | static void sysrq_handle_unrt(int key) |
| 388 | { |
| 389 | normalize_rt_tasks(); |
| 390 | } |
| 391 | static struct sysrq_key_op sysrq_unrt_op = { |
| 392 | .handler = sysrq_handle_unrt, |
| 393 | .help_msg = "nice-all-RT-tasks(N)", |
| 394 | .action_msg = "Nice All RT Tasks", |
| 395 | .enable_mask = SYSRQ_ENABLE_RTNICE, |
| 396 | }; |
| 397 | |
| 398 | /* Key Operations table and lock */ |
| 399 | static DEFINE_SPINLOCK(sysrq_key_table_lock); |
| 400 | |
| 401 | static struct sysrq_key_op *sysrq_key_table[36] = { |
| 402 | &sysrq_loglevel_op, /* 0 */ |
| 403 | &sysrq_loglevel_op, /* 1 */ |
| 404 | &sysrq_loglevel_op, /* 2 */ |
| 405 | &sysrq_loglevel_op, /* 3 */ |
| 406 | &sysrq_loglevel_op, /* 4 */ |
| 407 | &sysrq_loglevel_op, /* 5 */ |
| 408 | &sysrq_loglevel_op, /* 6 */ |
| 409 | &sysrq_loglevel_op, /* 7 */ |
| 410 | &sysrq_loglevel_op, /* 8 */ |
| 411 | &sysrq_loglevel_op, /* 9 */ |
| 412 | |
| 413 | /* |
| 414 | * a: Don't use for system provided sysrqs, it is handled specially on |
| 415 | * sparc and will never arrive. |
| 416 | */ |
| 417 | NULL, /* a */ |
| 418 | &sysrq_reboot_op, /* b */ |
| 419 | &sysrq_crash_op, /* c & ibm_emac driver debug */ |
| 420 | &sysrq_showlocks_op, /* d */ |
| 421 | &sysrq_term_op, /* e */ |
| 422 | &sysrq_moom_op, /* f */ |
| 423 | /* g: May be registered for the kernel debugger */ |
| 424 | NULL, /* g */ |
| 425 | NULL, /* h - reserved for help */ |
| 426 | &sysrq_kill_op, /* i */ |
| 427 | #ifdef CONFIG_BLOCK |
| 428 | &sysrq_thaw_op, /* j */ |
| 429 | #else |
| 430 | NULL, /* j */ |
| 431 | #endif |
| 432 | &sysrq_SAK_op, /* k */ |
| 433 | #ifdef CONFIG_SMP |
| 434 | &sysrq_showallcpus_op, /* l */ |
| 435 | #else |
| 436 | NULL, /* l */ |
| 437 | #endif |
| 438 | &sysrq_showmem_op, /* m */ |
| 439 | &sysrq_unrt_op, /* n */ |
| 440 | /* o: This will often be registered as 'Off' at init time */ |
| 441 | NULL, /* o */ |
| 442 | &sysrq_showregs_op, /* p */ |
| 443 | &sysrq_show_timers_op, /* q */ |
| 444 | &sysrq_unraw_op, /* r */ |
| 445 | &sysrq_sync_op, /* s */ |
| 446 | &sysrq_showstate_op, /* t */ |
| 447 | &sysrq_mountro_op, /* u */ |
| 448 | /* v: May be registered for frame buffer console restore */ |
| 449 | NULL, /* v */ |
| 450 | &sysrq_showstate_blocked_op, /* w */ |
| 451 | /* x: May be registered on ppc/powerpc for xmon */ |
| 452 | NULL, /* x */ |
| 453 | /* y: May be registered on sparc64 for global register dump */ |
| 454 | NULL, /* y */ |
| 455 | &sysrq_ftrace_dump_op, /* z */ |
| 456 | }; |
| 457 | |
| 458 | /* key2index calculation, -1 on invalid index */ |
| 459 | static int sysrq_key_table_key2index(int key) |
| 460 | { |
| 461 | int retval; |
| 462 | |
| 463 | if ((key >= '0') && (key <= '9')) |
| 464 | retval = key - '0'; |
| 465 | else if ((key >= 'a') && (key <= 'z')) |
| 466 | retval = key + 10 - 'a'; |
| 467 | else |
| 468 | retval = -1; |
| 469 | return retval; |
| 470 | } |
| 471 | |
| 472 | /* |
| 473 | * get and put functions for the table, exposed to modules. |
| 474 | */ |
| 475 | struct sysrq_key_op *__sysrq_get_key_op(int key) |
| 476 | { |
| 477 | struct sysrq_key_op *op_p = NULL; |
| 478 | int i; |
| 479 | |
| 480 | i = sysrq_key_table_key2index(key); |
| 481 | if (i != -1) |
| 482 | op_p = sysrq_key_table[i]; |
| 483 | |
| 484 | return op_p; |
| 485 | } |
| 486 | |
| 487 | static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p) |
| 488 | { |
| 489 | int i = sysrq_key_table_key2index(key); |
| 490 | |
| 491 | if (i != -1) |
| 492 | sysrq_key_table[i] = op_p; |
| 493 | } |
| 494 | |
| 495 | void __handle_sysrq(int key, bool check_mask) |
| 496 | { |
| 497 | struct sysrq_key_op *op_p; |
| 498 | int orig_log_level; |
| 499 | int i; |
| 500 | unsigned long flags; |
| 501 | |
| 502 | spin_lock_irqsave(&sysrq_key_table_lock, flags); |
| 503 | /* |
| 504 | * Raise the apparent loglevel to maximum so that the sysrq header |
| 505 | * is shown to provide the user with positive feedback. We do not |
| 506 | * simply emit this at KERN_EMERG as that would change message |
| 507 | * routing in the consumers of /proc/kmsg. |
| 508 | */ |
| 509 | orig_log_level = console_loglevel; |
| 510 | console_loglevel = 7; |
| 511 | printk(KERN_INFO "SysRq : "); |
| 512 | |
| 513 | op_p = __sysrq_get_key_op(key); |
| 514 | if (op_p) { |
| 515 | /* |
| 516 | * Should we check for enabled operations (/proc/sysrq-trigger |
| 517 | * should not) and is the invoked operation enabled? |
| 518 | */ |
| 519 | if (!check_mask || sysrq_on_mask(op_p->enable_mask)) { |
| 520 | printk("%s\n", op_p->action_msg); |
| 521 | console_loglevel = orig_log_level; |
| 522 | op_p->handler(key); |
| 523 | } else { |
| 524 | printk("This sysrq operation is disabled.\n"); |
| 525 | } |
| 526 | } else { |
| 527 | printk("HELP : "); |
| 528 | /* Only print the help msg once per handler */ |
| 529 | for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) { |
| 530 | if (sysrq_key_table[i]) { |
| 531 | int j; |
| 532 | |
| 533 | for (j = 0; sysrq_key_table[i] != |
| 534 | sysrq_key_table[j]; j++) |
| 535 | ; |
| 536 | if (j != i) |
| 537 | continue; |
| 538 | printk("%s ", sysrq_key_table[i]->help_msg); |
| 539 | } |
| 540 | } |
| 541 | printk("\n"); |
| 542 | console_loglevel = orig_log_level; |
| 543 | } |
| 544 | spin_unlock_irqrestore(&sysrq_key_table_lock, flags); |
| 545 | } |
| 546 | |
| 547 | void handle_sysrq(int key) |
| 548 | { |
| 549 | if (sysrq_on()) |
| 550 | __handle_sysrq(key, true); |
| 551 | } |
| 552 | EXPORT_SYMBOL(handle_sysrq); |
| 553 | |
| 554 | #ifdef CONFIG_INPUT |
| 555 | |
| 556 | /* Simple translation table for the SysRq keys */ |
| 557 | static const unsigned char sysrq_xlate[KEY_CNT] = |
| 558 | "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */ |
| 559 | "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */ |
| 560 | "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */ |
| 561 | "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */ |
| 562 | "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */ |
| 563 | "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */ |
| 564 | "\r\000/"; /* 0x60 - 0x6f */ |
| 565 | |
| 566 | struct sysrq_state { |
| 567 | struct input_handle handle; |
| 568 | struct work_struct reinject_work; |
| 569 | unsigned long key_down[BITS_TO_LONGS(KEY_CNT)]; |
| 570 | unsigned int alt; |
| 571 | unsigned int alt_use; |
| 572 | bool active; |
| 573 | bool need_reinject; |
| 574 | bool reinjecting; |
| 575 | }; |
| 576 | |
| 577 | static void sysrq_reinject_alt_sysrq(struct work_struct *work) |
| 578 | { |
| 579 | struct sysrq_state *sysrq = |
| 580 | container_of(work, struct sysrq_state, reinject_work); |
| 581 | struct input_handle *handle = &sysrq->handle; |
| 582 | unsigned int alt_code = sysrq->alt_use; |
| 583 | |
| 584 | if (sysrq->need_reinject) { |
| 585 | /* we do not want the assignment to be reordered */ |
| 586 | sysrq->reinjecting = true; |
| 587 | mb(); |
| 588 | |
| 589 | /* Simulate press and release of Alt + SysRq */ |
| 590 | input_inject_event(handle, EV_KEY, alt_code, 1); |
| 591 | input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1); |
| 592 | input_inject_event(handle, EV_SYN, SYN_REPORT, 1); |
| 593 | |
| 594 | input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0); |
| 595 | input_inject_event(handle, EV_KEY, alt_code, 0); |
| 596 | input_inject_event(handle, EV_SYN, SYN_REPORT, 1); |
| 597 | |
| 598 | mb(); |
| 599 | sysrq->reinjecting = false; |
| 600 | } |
| 601 | } |
| 602 | |
| 603 | static bool sysrq_filter(struct input_handle *handle, |
| 604 | unsigned int type, unsigned int code, int value) |
| 605 | { |
| 606 | struct sysrq_state *sysrq = handle->private; |
| 607 | bool was_active = sysrq->active; |
| 608 | bool suppress; |
| 609 | |
| 610 | /* |
| 611 | * Do not filter anything if we are in the process of re-injecting |
| 612 | * Alt+SysRq combination. |
| 613 | */ |
| 614 | if (sysrq->reinjecting) |
| 615 | return false; |
| 616 | |
| 617 | switch (type) { |
| 618 | |
| 619 | case EV_SYN: |
| 620 | suppress = false; |
| 621 | break; |
| 622 | |
| 623 | case EV_KEY: |
| 624 | switch (code) { |
| 625 | |
| 626 | case KEY_LEFTALT: |
| 627 | case KEY_RIGHTALT: |
| 628 | if (!value) { |
| 629 | /* One of ALTs is being released */ |
| 630 | if (sysrq->active && code == sysrq->alt_use) |
| 631 | sysrq->active = false; |
| 632 | |
| 633 | sysrq->alt = KEY_RESERVED; |
| 634 | |
| 635 | } else if (value != 2) { |
| 636 | sysrq->alt = code; |
| 637 | sysrq->need_reinject = false; |
| 638 | } |
| 639 | break; |
| 640 | |
| 641 | case KEY_SYSRQ: |
| 642 | if (value == 1 && sysrq->alt != KEY_RESERVED) { |
| 643 | sysrq->active = true; |
| 644 | sysrq->alt_use = sysrq->alt; |
| 645 | /* |
| 646 | * If nothing else will be pressed we'll need |
| 647 | * to re-inject Alt-SysRq keysroke. |
| 648 | */ |
| 649 | sysrq->need_reinject = true; |
| 650 | } |
| 651 | |
| 652 | /* |
| 653 | * Pretend that sysrq was never pressed at all. This |
| 654 | * is needed to properly handle KGDB which will try |
| 655 | * to release all keys after exiting debugger. If we |
| 656 | * do not clear key bit it KGDB will end up sending |
| 657 | * release events for Alt and SysRq, potentially |
| 658 | * triggering print screen function. |
| 659 | */ |
| 660 | if (sysrq->active) |
| 661 | clear_bit(KEY_SYSRQ, handle->dev->key); |
| 662 | |
| 663 | break; |
| 664 | |
| 665 | default: |
| 666 | if (sysrq->active && value && value != 2) { |
| 667 | sysrq->need_reinject = false; |
| 668 | __handle_sysrq(sysrq_xlate[code], true); |
| 669 | } |
| 670 | break; |
| 671 | } |
| 672 | |
| 673 | suppress = sysrq->active; |
| 674 | |
| 675 | if (!sysrq->active) { |
| 676 | /* |
| 677 | * If we are not suppressing key presses keep track of |
| 678 | * keyboard state so we can release keys that have been |
| 679 | * pressed before entering SysRq mode. |
| 680 | */ |
| 681 | if (value) |
| 682 | set_bit(code, sysrq->key_down); |
| 683 | else |
| 684 | clear_bit(code, sysrq->key_down); |
| 685 | |
| 686 | if (was_active) |
| 687 | schedule_work(&sysrq->reinject_work); |
| 688 | |
| 689 | } else if (value == 0 && |
| 690 | test_and_clear_bit(code, sysrq->key_down)) { |
| 691 | /* |
| 692 | * Pass on release events for keys that was pressed before |
| 693 | * entering SysRq mode. |
| 694 | */ |
| 695 | suppress = false; |
| 696 | } |
| 697 | break; |
| 698 | |
| 699 | default: |
| 700 | suppress = sysrq->active; |
| 701 | break; |
| 702 | } |
| 703 | |
| 704 | return suppress; |
| 705 | } |
| 706 | |
| 707 | static int sysrq_connect(struct input_handler *handler, |
| 708 | struct input_dev *dev, |
| 709 | const struct input_device_id *id) |
| 710 | { |
| 711 | struct sysrq_state *sysrq; |
| 712 | int error; |
| 713 | |
| 714 | sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL); |
| 715 | if (!sysrq) |
| 716 | return -ENOMEM; |
| 717 | |
| 718 | INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq); |
| 719 | |
| 720 | sysrq->handle.dev = dev; |
| 721 | sysrq->handle.handler = handler; |
| 722 | sysrq->handle.name = "sysrq"; |
| 723 | sysrq->handle.private = sysrq; |
| 724 | |
| 725 | error = input_register_handle(&sysrq->handle); |
| 726 | if (error) { |
| 727 | pr_err("Failed to register input sysrq handler, error %d\n", |
| 728 | error); |
| 729 | goto err_free; |
| 730 | } |
| 731 | |
| 732 | error = input_open_device(&sysrq->handle); |
| 733 | if (error) { |
| 734 | pr_err("Failed to open input device, error %d\n", error); |
| 735 | goto err_unregister; |
| 736 | } |
| 737 | |
| 738 | return 0; |
| 739 | |
| 740 | err_unregister: |
| 741 | input_unregister_handle(&sysrq->handle); |
| 742 | err_free: |
| 743 | kfree(sysrq); |
| 744 | return error; |
| 745 | } |
| 746 | |
| 747 | static void sysrq_disconnect(struct input_handle *handle) |
| 748 | { |
| 749 | struct sysrq_state *sysrq = handle->private; |
| 750 | |
| 751 | input_close_device(handle); |
| 752 | cancel_work_sync(&sysrq->reinject_work); |
| 753 | input_unregister_handle(handle); |
| 754 | kfree(sysrq); |
| 755 | } |
| 756 | |
| 757 | /* |
| 758 | * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all |
| 759 | * keyboards have SysRq key predefined and so user may add it to keymap |
| 760 | * later, but we expect all such keyboards to have left alt. |
| 761 | */ |
| 762 | static const struct input_device_id sysrq_ids[] = { |
| 763 | { |
| 764 | .flags = INPUT_DEVICE_ID_MATCH_EVBIT | |
| 765 | INPUT_DEVICE_ID_MATCH_KEYBIT, |
| 766 | .evbit = { BIT_MASK(EV_KEY) }, |
| 767 | .keybit = { BIT_MASK(KEY_LEFTALT) }, |
| 768 | }, |
| 769 | { }, |
| 770 | }; |
| 771 | |
| 772 | static struct input_handler sysrq_handler = { |
| 773 | .filter = sysrq_filter, |
| 774 | .connect = sysrq_connect, |
| 775 | .disconnect = sysrq_disconnect, |
| 776 | .name = "sysrq", |
| 777 | .id_table = sysrq_ids, |
| 778 | }; |
| 779 | |
| 780 | static bool sysrq_handler_registered; |
| 781 | |
| 782 | static inline void sysrq_register_handler(void) |
| 783 | { |
| 784 | int error; |
| 785 | |
| 786 | error = input_register_handler(&sysrq_handler); |
| 787 | if (error) |
| 788 | pr_err("Failed to register input handler, error %d", error); |
| 789 | else |
| 790 | sysrq_handler_registered = true; |
| 791 | } |
| 792 | |
| 793 | static inline void sysrq_unregister_handler(void) |
| 794 | { |
| 795 | if (sysrq_handler_registered) { |
| 796 | input_unregister_handler(&sysrq_handler); |
| 797 | sysrq_handler_registered = false; |
| 798 | } |
| 799 | } |
| 800 | |
| 801 | #else |
| 802 | |
| 803 | static inline void sysrq_register_handler(void) |
| 804 | { |
| 805 | } |
| 806 | |
| 807 | static inline void sysrq_unregister_handler(void) |
| 808 | { |
| 809 | } |
| 810 | |
| 811 | #endif /* CONFIG_INPUT */ |
| 812 | |
| 813 | int sysrq_toggle_support(int enable_mask) |
| 814 | { |
| 815 | bool was_enabled = sysrq_on(); |
| 816 | |
| 817 | sysrq_enabled = enable_mask; |
| 818 | |
| 819 | if (was_enabled != sysrq_on()) { |
| 820 | if (sysrq_on()) |
| 821 | sysrq_register_handler(); |
| 822 | else |
| 823 | sysrq_unregister_handler(); |
| 824 | } |
| 825 | |
| 826 | return 0; |
| 827 | } |
| 828 | |
| 829 | static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p, |
| 830 | struct sysrq_key_op *remove_op_p) |
| 831 | { |
| 832 | int retval; |
| 833 | unsigned long flags; |
| 834 | |
| 835 | spin_lock_irqsave(&sysrq_key_table_lock, flags); |
| 836 | if (__sysrq_get_key_op(key) == remove_op_p) { |
| 837 | __sysrq_put_key_op(key, insert_op_p); |
| 838 | retval = 0; |
| 839 | } else { |
| 840 | retval = -1; |
| 841 | } |
| 842 | spin_unlock_irqrestore(&sysrq_key_table_lock, flags); |
| 843 | return retval; |
| 844 | } |
| 845 | |
| 846 | int register_sysrq_key(int key, struct sysrq_key_op *op_p) |
| 847 | { |
| 848 | return __sysrq_swap_key_ops(key, op_p, NULL); |
| 849 | } |
| 850 | EXPORT_SYMBOL(register_sysrq_key); |
| 851 | |
| 852 | int unregister_sysrq_key(int key, struct sysrq_key_op *op_p) |
| 853 | { |
| 854 | return __sysrq_swap_key_ops(key, NULL, op_p); |
| 855 | } |
| 856 | EXPORT_SYMBOL(unregister_sysrq_key); |
| 857 | |
| 858 | #ifdef CONFIG_PROC_FS |
| 859 | /* |
| 860 | * writing 'C' to /proc/sysrq-trigger is like sysrq-C |
| 861 | */ |
| 862 | static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf, |
| 863 | size_t count, loff_t *ppos) |
| 864 | { |
| 865 | if (count) { |
| 866 | char c; |
| 867 | |
| 868 | if (get_user(c, buf)) |
| 869 | return -EFAULT; |
| 870 | __handle_sysrq(c, false); |
| 871 | } |
| 872 | |
| 873 | return count; |
| 874 | } |
| 875 | |
| 876 | static const struct file_operations proc_sysrq_trigger_operations = { |
| 877 | .write = write_sysrq_trigger, |
| 878 | .llseek = noop_llseek, |
| 879 | }; |
| 880 | |
| 881 | static void sysrq_init_procfs(void) |
| 882 | { |
| 883 | if (!proc_create("sysrq-trigger", S_IWUSR, NULL, |
| 884 | &proc_sysrq_trigger_operations)) |
| 885 | pr_err("Failed to register proc interface\n"); |
| 886 | } |
| 887 | |
| 888 | #else |
| 889 | |
| 890 | static inline void sysrq_init_procfs(void) |
| 891 | { |
| 892 | } |
| 893 | |
| 894 | #endif /* CONFIG_PROC_FS */ |
| 895 | |
| 896 | static int __init sysrq_init(void) |
| 897 | { |
| 898 | sysrq_init_procfs(); |
| 899 | |
| 900 | if (sysrq_on()) |
| 901 | sysrq_register_handler(); |
| 902 | |
| 903 | return 0; |
| 904 | } |
| 905 | module_init(sysrq_init); |