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/swap.h> 36 #include <linux/spinlock.h> 37 #include <linux/vt_kern.h> 38 #include <linux/workqueue.h> 39 #include <linux/hrtimer.h> 40 #include <linux/oom.h> 41 #include <linux/slab.h> 42 #include <linux/input.h> 43 #include <linux/uaccess.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 vt_reset_unicode(fg_console); 114 } 115 116 static struct sysrq_key_op sysrq_unraw_op = { 117 .handler = sysrq_handle_unraw, 118 .help_msg = "unRaw", 119 .action_msg = "Keyboard mode set to system default", 120 .enable_mask = SYSRQ_ENABLE_KEYBOARD, 121 }; 122 #else 123 #define sysrq_unraw_op (*(struct sysrq_key_op *)NULL) 124 #endif /* CONFIG_VT */ 125 126 static void sysrq_handle_crash(int key) 127 { 128 char *killer = NULL; 129 130 panic_on_oops = 1; /* force panic */ 131 wmb(); 132 *killer = 1; 133 } 134 static struct sysrq_key_op sysrq_crash_op = { 135 .handler = sysrq_handle_crash, 136 .help_msg = "Crash", 137 .action_msg = "Trigger a crash", 138 .enable_mask = SYSRQ_ENABLE_DUMP, 139 }; 140 141 static void sysrq_handle_reboot(int key) 142 { 143 lockdep_off(); 144 local_irq_enable(); 145 emergency_restart(); 146 } 147 static struct sysrq_key_op sysrq_reboot_op = { 148 .handler = sysrq_handle_reboot, 149 .help_msg = "reBoot", 150 .action_msg = "Resetting", 151 .enable_mask = SYSRQ_ENABLE_BOOT, 152 }; 153 154 static void sysrq_handle_sync(int key) 155 { 156 emergency_sync(); 157 } 158 static struct sysrq_key_op sysrq_sync_op = { 159 .handler = sysrq_handle_sync, 160 .help_msg = "Sync", 161 .action_msg = "Emergency Sync", 162 .enable_mask = SYSRQ_ENABLE_SYNC, 163 }; 164 165 static void sysrq_handle_show_timers(int key) 166 { 167 sysrq_timer_list_show(); 168 } 169 170 static struct sysrq_key_op sysrq_show_timers_op = { 171 .handler = sysrq_handle_show_timers, 172 .help_msg = "show-all-timers(Q)", 173 .action_msg = "Show clockevent devices & pending hrtimers (no others)", 174 }; 175 176 static void sysrq_handle_mountro(int key) 177 { 178 emergency_remount(); 179 } 180 static struct sysrq_key_op sysrq_mountro_op = { 181 .handler = sysrq_handle_mountro, 182 .help_msg = "Unmount", 183 .action_msg = "Emergency Remount R/O", 184 .enable_mask = SYSRQ_ENABLE_REMOUNT, 185 }; 186 187 #ifdef CONFIG_LOCKDEP 188 static void sysrq_handle_showlocks(int key) 189 { 190 debug_show_all_locks(); 191 } 192 193 static struct sysrq_key_op sysrq_showlocks_op = { 194 .handler = sysrq_handle_showlocks, 195 .help_msg = "show-all-locks(D)", 196 .action_msg = "Show Locks Held", 197 }; 198 #else 199 #define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL) 200 #endif 201 202 #ifdef CONFIG_SMP 203 static DEFINE_SPINLOCK(show_lock); 204 205 static void showacpu(void *dummy) 206 { 207 unsigned long flags; 208 209 /* Idle CPUs have no interesting backtrace. */ 210 if (idle_cpu(smp_processor_id())) 211 return; 212 213 spin_lock_irqsave(&show_lock, flags); 214 printk(KERN_INFO "CPU%d:\n", smp_processor_id()); 215 show_stack(NULL, NULL); 216 spin_unlock_irqrestore(&show_lock, flags); 217 } 218 219 static void sysrq_showregs_othercpus(struct work_struct *dummy) 220 { 221 smp_call_function(showacpu, NULL, 0); 222 } 223 224 static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus); 225 226 static void sysrq_handle_showallcpus(int key) 227 { 228 /* 229 * Fall back to the workqueue based printing if the 230 * backtrace printing did not succeed or the 231 * architecture has no support for it: 232 */ 233 if (!trigger_all_cpu_backtrace()) { 234 struct pt_regs *regs = get_irq_regs(); 235 236 if (regs) { 237 printk(KERN_INFO "CPU%d:\n", smp_processor_id()); 238 show_regs(regs); 239 } 240 schedule_work(&sysrq_showallcpus); 241 } 242 } 243 244 static struct sysrq_key_op sysrq_showallcpus_op = { 245 .handler = sysrq_handle_showallcpus, 246 .help_msg = "show-backtrace-all-active-cpus(L)", 247 .action_msg = "Show backtrace of all active CPUs", 248 .enable_mask = SYSRQ_ENABLE_DUMP, 249 }; 250 #endif 251 252 static void sysrq_handle_showregs(int key) 253 { 254 struct pt_regs *regs = get_irq_regs(); 255 if (regs) 256 show_regs(regs); 257 perf_event_print_debug(); 258 } 259 static struct sysrq_key_op sysrq_showregs_op = { 260 .handler = sysrq_handle_showregs, 261 .help_msg = "show-registers(P)", 262 .action_msg = "Show Regs", 263 .enable_mask = SYSRQ_ENABLE_DUMP, 264 }; 265 266 static void sysrq_handle_showstate(int key) 267 { 268 show_state(); 269 } 270 static struct sysrq_key_op sysrq_showstate_op = { 271 .handler = sysrq_handle_showstate, 272 .help_msg = "show-task-states(T)", 273 .action_msg = "Show State", 274 .enable_mask = SYSRQ_ENABLE_DUMP, 275 }; 276 277 static void sysrq_handle_showstate_blocked(int key) 278 { 279 show_state_filter(TASK_UNINTERRUPTIBLE); 280 } 281 static struct sysrq_key_op sysrq_showstate_blocked_op = { 282 .handler = sysrq_handle_showstate_blocked, 283 .help_msg = "show-blocked-tasks(W)", 284 .action_msg = "Show Blocked State", 285 .enable_mask = SYSRQ_ENABLE_DUMP, 286 }; 287 288 #ifdef CONFIG_TRACING 289 #include <linux/ftrace.h> 290 291 static void sysrq_ftrace_dump(int key) 292 { 293 ftrace_dump(DUMP_ALL); 294 } 295 static struct sysrq_key_op sysrq_ftrace_dump_op = { 296 .handler = sysrq_ftrace_dump, 297 .help_msg = "dump-ftrace-buffer(Z)", 298 .action_msg = "Dump ftrace buffer", 299 .enable_mask = SYSRQ_ENABLE_DUMP, 300 }; 301 #else 302 #define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL) 303 #endif 304 305 static void sysrq_handle_showmem(int key) 306 { 307 show_mem(0); 308 } 309 static struct sysrq_key_op sysrq_showmem_op = { 310 .handler = sysrq_handle_showmem, 311 .help_msg = "show-memory-usage(M)", 312 .action_msg = "Show Memory", 313 .enable_mask = SYSRQ_ENABLE_DUMP, 314 }; 315 316 /* 317 * Signal sysrq helper function. Sends a signal to all user processes. 318 */ 319 static void send_sig_all(int sig) 320 { 321 struct task_struct *p; 322 323 read_lock(&tasklist_lock); 324 for_each_process(p) { 325 if (p->flags & PF_KTHREAD) 326 continue; 327 if (is_global_init(p)) 328 continue; 329 330 do_send_sig_info(sig, SEND_SIG_FORCED, p, true); 331 } 332 read_unlock(&tasklist_lock); 333 } 334 335 static void sysrq_handle_term(int key) 336 { 337 send_sig_all(SIGTERM); 338 console_loglevel = 8; 339 } 340 static struct sysrq_key_op sysrq_term_op = { 341 .handler = sysrq_handle_term, 342 .help_msg = "terminate-all-tasks(E)", 343 .action_msg = "Terminate All Tasks", 344 .enable_mask = SYSRQ_ENABLE_SIGNAL, 345 }; 346 347 static void moom_callback(struct work_struct *ignored) 348 { 349 out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0, NULL, true); 350 } 351 352 static DECLARE_WORK(moom_work, moom_callback); 353 354 static void sysrq_handle_moom(int key) 355 { 356 schedule_work(&moom_work); 357 } 358 static struct sysrq_key_op sysrq_moom_op = { 359 .handler = sysrq_handle_moom, 360 .help_msg = "memory-full-oom-kill(F)", 361 .action_msg = "Manual OOM execution", 362 .enable_mask = SYSRQ_ENABLE_SIGNAL, 363 }; 364 365 #ifdef CONFIG_BLOCK 366 static void sysrq_handle_thaw(int key) 367 { 368 emergency_thaw_all(); 369 } 370 static struct sysrq_key_op sysrq_thaw_op = { 371 .handler = sysrq_handle_thaw, 372 .help_msg = "thaw-filesystems(J)", 373 .action_msg = "Emergency Thaw of all frozen filesystems", 374 .enable_mask = SYSRQ_ENABLE_SIGNAL, 375 }; 376 #endif 377 378 static void sysrq_handle_kill(int key) 379 { 380 send_sig_all(SIGKILL); 381 console_loglevel = 8; 382 } 383 static struct sysrq_key_op sysrq_kill_op = { 384 .handler = sysrq_handle_kill, 385 .help_msg = "kill-all-tasks(I)", 386 .action_msg = "Kill All Tasks", 387 .enable_mask = SYSRQ_ENABLE_SIGNAL, 388 }; 389 390 static void sysrq_handle_unrt(int key) 391 { 392 normalize_rt_tasks(); 393 } 394 static struct sysrq_key_op sysrq_unrt_op = { 395 .handler = sysrq_handle_unrt, 396 .help_msg = "nice-all-RT-tasks(N)", 397 .action_msg = "Nice All RT Tasks", 398 .enable_mask = SYSRQ_ENABLE_RTNICE, 399 }; 400 401 /* Key Operations table and lock */ 402 static DEFINE_SPINLOCK(sysrq_key_table_lock); 403 404 static struct sysrq_key_op *sysrq_key_table[36] = { 405 &sysrq_loglevel_op, /* 0 */ 406 &sysrq_loglevel_op, /* 1 */ 407 &sysrq_loglevel_op, /* 2 */ 408 &sysrq_loglevel_op, /* 3 */ 409 &sysrq_loglevel_op, /* 4 */ 410 &sysrq_loglevel_op, /* 5 */ 411 &sysrq_loglevel_op, /* 6 */ 412 &sysrq_loglevel_op, /* 7 */ 413 &sysrq_loglevel_op, /* 8 */ 414 &sysrq_loglevel_op, /* 9 */ 415 416 /* 417 * a: Don't use for system provided sysrqs, it is handled specially on 418 * sparc and will never arrive. 419 */ 420 NULL, /* a */ 421 &sysrq_reboot_op, /* b */ 422 &sysrq_crash_op, /* c & ibm_emac driver debug */ 423 &sysrq_showlocks_op, /* d */ 424 &sysrq_term_op, /* e */ 425 &sysrq_moom_op, /* f */ 426 /* g: May be registered for the kernel debugger */ 427 NULL, /* g */ 428 NULL, /* h - reserved for help */ 429 &sysrq_kill_op, /* i */ 430 #ifdef CONFIG_BLOCK 431 &sysrq_thaw_op, /* j */ 432 #else 433 NULL, /* j */ 434 #endif 435 &sysrq_SAK_op, /* k */ 436 #ifdef CONFIG_SMP 437 &sysrq_showallcpus_op, /* l */ 438 #else 439 NULL, /* l */ 440 #endif 441 &sysrq_showmem_op, /* m */ 442 &sysrq_unrt_op, /* n */ 443 /* o: This will often be registered as 'Off' at init time */ 444 NULL, /* o */ 445 &sysrq_showregs_op, /* p */ 446 &sysrq_show_timers_op, /* q */ 447 &sysrq_unraw_op, /* r */ 448 &sysrq_sync_op, /* s */ 449 &sysrq_showstate_op, /* t */ 450 &sysrq_mountro_op, /* u */ 451 /* v: May be registered for frame buffer console restore */ 452 NULL, /* v */ 453 &sysrq_showstate_blocked_op, /* w */ 454 /* x: May be registered on ppc/powerpc for xmon */ 455 /* x: May be registered on sparc64 for global PMU dump */ 456 NULL, /* x */ 457 /* y: May be registered on sparc64 for global register dump */ 458 NULL, /* y */ 459 &sysrq_ftrace_dump_op, /* z */ 460 }; 461 462 /* key2index calculation, -1 on invalid index */ 463 static int sysrq_key_table_key2index(int key) 464 { 465 int retval; 466 467 if ((key >= '0') && (key <= '9')) 468 retval = key - '0'; 469 else if ((key >= 'a') && (key <= 'z')) 470 retval = key + 10 - 'a'; 471 else 472 retval = -1; 473 return retval; 474 } 475 476 /* 477 * get and put functions for the table, exposed to modules. 478 */ 479 struct sysrq_key_op *__sysrq_get_key_op(int key) 480 { 481 struct sysrq_key_op *op_p = NULL; 482 int i; 483 484 i = sysrq_key_table_key2index(key); 485 if (i != -1) 486 op_p = sysrq_key_table[i]; 487 488 return op_p; 489 } 490 491 static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p) 492 { 493 int i = sysrq_key_table_key2index(key); 494 495 if (i != -1) 496 sysrq_key_table[i] = op_p; 497 } 498 499 void __handle_sysrq(int key, bool check_mask) 500 { 501 struct sysrq_key_op *op_p; 502 int orig_log_level; 503 int i; 504 unsigned long flags; 505 506 spin_lock_irqsave(&sysrq_key_table_lock, flags); 507 /* 508 * Raise the apparent loglevel to maximum so that the sysrq header 509 * is shown to provide the user with positive feedback. We do not 510 * simply emit this at KERN_EMERG as that would change message 511 * routing in the consumers of /proc/kmsg. 512 */ 513 orig_log_level = console_loglevel; 514 console_loglevel = 7; 515 printk(KERN_INFO "SysRq : "); 516 517 op_p = __sysrq_get_key_op(key); 518 if (op_p) { 519 /* 520 * Should we check for enabled operations (/proc/sysrq-trigger 521 * should not) and is the invoked operation enabled? 522 */ 523 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) { 524 printk("%s\n", op_p->action_msg); 525 console_loglevel = orig_log_level; 526 op_p->handler(key); 527 } else { 528 printk("This sysrq operation is disabled.\n"); 529 } 530 } else { 531 printk("HELP : "); 532 /* Only print the help msg once per handler */ 533 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) { 534 if (sysrq_key_table[i]) { 535 int j; 536 537 for (j = 0; sysrq_key_table[i] != 538 sysrq_key_table[j]; j++) 539 ; 540 if (j != i) 541 continue; 542 printk("%s ", sysrq_key_table[i]->help_msg); 543 } 544 } 545 printk("\n"); 546 console_loglevel = orig_log_level; 547 } 548 spin_unlock_irqrestore(&sysrq_key_table_lock, flags); 549 } 550 551 void handle_sysrq(int key) 552 { 553 if (sysrq_on()) 554 __handle_sysrq(key, true); 555 } 556 EXPORT_SYMBOL(handle_sysrq); 557 558 #ifdef CONFIG_INPUT 559 560 /* Simple translation table for the SysRq keys */ 561 static const unsigned char sysrq_xlate[KEY_CNT] = 562 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */ 563 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */ 564 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */ 565 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */ 566 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */ 567 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */ 568 "\r\000/"; /* 0x60 - 0x6f */ 569 570 struct sysrq_state { 571 struct input_handle handle; 572 struct work_struct reinject_work; 573 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)]; 574 unsigned int alt; 575 unsigned int alt_use; 576 bool active; 577 bool need_reinject; 578 bool reinjecting; 579 }; 580 581 static void sysrq_reinject_alt_sysrq(struct work_struct *work) 582 { 583 struct sysrq_state *sysrq = 584 container_of(work, struct sysrq_state, reinject_work); 585 struct input_handle *handle = &sysrq->handle; 586 unsigned int alt_code = sysrq->alt_use; 587 588 if (sysrq->need_reinject) { 589 /* we do not want the assignment to be reordered */ 590 sysrq->reinjecting = true; 591 mb(); 592 593 /* Simulate press and release of Alt + SysRq */ 594 input_inject_event(handle, EV_KEY, alt_code, 1); 595 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1); 596 input_inject_event(handle, EV_SYN, SYN_REPORT, 1); 597 598 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0); 599 input_inject_event(handle, EV_KEY, alt_code, 0); 600 input_inject_event(handle, EV_SYN, SYN_REPORT, 1); 601 602 mb(); 603 sysrq->reinjecting = false; 604 } 605 } 606 607 static bool sysrq_filter(struct input_handle *handle, 608 unsigned int type, unsigned int code, int value) 609 { 610 struct sysrq_state *sysrq = handle->private; 611 bool was_active = sysrq->active; 612 bool suppress; 613 614 /* 615 * Do not filter anything if we are in the process of re-injecting 616 * Alt+SysRq combination. 617 */ 618 if (sysrq->reinjecting) 619 return false; 620 621 switch (type) { 622 623 case EV_SYN: 624 suppress = false; 625 break; 626 627 case EV_KEY: 628 switch (code) { 629 630 case KEY_LEFTALT: 631 case KEY_RIGHTALT: 632 if (!value) { 633 /* One of ALTs is being released */ 634 if (sysrq->active && code == sysrq->alt_use) 635 sysrq->active = false; 636 637 sysrq->alt = KEY_RESERVED; 638 639 } else if (value != 2) { 640 sysrq->alt = code; 641 sysrq->need_reinject = false; 642 } 643 break; 644 645 case KEY_SYSRQ: 646 if (value == 1 && sysrq->alt != KEY_RESERVED) { 647 sysrq->active = true; 648 sysrq->alt_use = sysrq->alt; 649 /* 650 * If nothing else will be pressed we'll need 651 * to re-inject Alt-SysRq keysroke. 652 */ 653 sysrq->need_reinject = true; 654 } 655 656 /* 657 * Pretend that sysrq was never pressed at all. This 658 * is needed to properly handle KGDB which will try 659 * to release all keys after exiting debugger. If we 660 * do not clear key bit it KGDB will end up sending 661 * release events for Alt and SysRq, potentially 662 * triggering print screen function. 663 */ 664 if (sysrq->active) 665 clear_bit(KEY_SYSRQ, handle->dev->key); 666 667 break; 668 669 default: 670 if (sysrq->active && value && value != 2) { 671 sysrq->need_reinject = false; 672 __handle_sysrq(sysrq_xlate[code], true); 673 } 674 break; 675 } 676 677 suppress = sysrq->active; 678 679 if (!sysrq->active) { 680 /* 681 * If we are not suppressing key presses keep track of 682 * keyboard state so we can release keys that have been 683 * pressed before entering SysRq mode. 684 */ 685 if (value) 686 set_bit(code, sysrq->key_down); 687 else 688 clear_bit(code, sysrq->key_down); 689 690 if (was_active) 691 schedule_work(&sysrq->reinject_work); 692 693 } else if (value == 0 && 694 test_and_clear_bit(code, sysrq->key_down)) { 695 /* 696 * Pass on release events for keys that was pressed before 697 * entering SysRq mode. 698 */ 699 suppress = false; 700 } 701 break; 702 703 default: 704 suppress = sysrq->active; 705 break; 706 } 707 708 return suppress; 709 } 710 711 static int sysrq_connect(struct input_handler *handler, 712 struct input_dev *dev, 713 const struct input_device_id *id) 714 { 715 struct sysrq_state *sysrq; 716 int error; 717 718 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL); 719 if (!sysrq) 720 return -ENOMEM; 721 722 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq); 723 724 sysrq->handle.dev = dev; 725 sysrq->handle.handler = handler; 726 sysrq->handle.name = "sysrq"; 727 sysrq->handle.private = sysrq; 728 729 error = input_register_handle(&sysrq->handle); 730 if (error) { 731 pr_err("Failed to register input sysrq handler, error %d\n", 732 error); 733 goto err_free; 734 } 735 736 error = input_open_device(&sysrq->handle); 737 if (error) { 738 pr_err("Failed to open input device, error %d\n", error); 739 goto err_unregister; 740 } 741 742 return 0; 743 744 err_unregister: 745 input_unregister_handle(&sysrq->handle); 746 err_free: 747 kfree(sysrq); 748 return error; 749 } 750 751 static void sysrq_disconnect(struct input_handle *handle) 752 { 753 struct sysrq_state *sysrq = handle->private; 754 755 input_close_device(handle); 756 cancel_work_sync(&sysrq->reinject_work); 757 input_unregister_handle(handle); 758 kfree(sysrq); 759 } 760 761 /* 762 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all 763 * keyboards have SysRq key predefined and so user may add it to keymap 764 * later, but we expect all such keyboards to have left alt. 765 */ 766 static const struct input_device_id sysrq_ids[] = { 767 { 768 .flags = INPUT_DEVICE_ID_MATCH_EVBIT | 769 INPUT_DEVICE_ID_MATCH_KEYBIT, 770 .evbit = { BIT_MASK(EV_KEY) }, 771 .keybit = { BIT_MASK(KEY_LEFTALT) }, 772 }, 773 { }, 774 }; 775 776 static struct input_handler sysrq_handler = { 777 .filter = sysrq_filter, 778 .connect = sysrq_connect, 779 .disconnect = sysrq_disconnect, 780 .name = "sysrq", 781 .id_table = sysrq_ids, 782 }; 783 784 static bool sysrq_handler_registered; 785 786 static inline void sysrq_register_handler(void) 787 { 788 int error; 789 790 error = input_register_handler(&sysrq_handler); 791 if (error) 792 pr_err("Failed to register input handler, error %d", error); 793 else 794 sysrq_handler_registered = true; 795 } 796 797 static inline void sysrq_unregister_handler(void) 798 { 799 if (sysrq_handler_registered) { 800 input_unregister_handler(&sysrq_handler); 801 sysrq_handler_registered = false; 802 } 803 } 804 805 #else 806 807 static inline void sysrq_register_handler(void) 808 { 809 } 810 811 static inline void sysrq_unregister_handler(void) 812 { 813 } 814 815 #endif /* CONFIG_INPUT */ 816 817 int sysrq_toggle_support(int enable_mask) 818 { 819 bool was_enabled = sysrq_on(); 820 821 sysrq_enabled = enable_mask; 822 823 if (was_enabled != sysrq_on()) { 824 if (sysrq_on()) 825 sysrq_register_handler(); 826 else 827 sysrq_unregister_handler(); 828 } 829 830 return 0; 831 } 832 833 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p, 834 struct sysrq_key_op *remove_op_p) 835 { 836 int retval; 837 unsigned long flags; 838 839 spin_lock_irqsave(&sysrq_key_table_lock, flags); 840 if (__sysrq_get_key_op(key) == remove_op_p) { 841 __sysrq_put_key_op(key, insert_op_p); 842 retval = 0; 843 } else { 844 retval = -1; 845 } 846 spin_unlock_irqrestore(&sysrq_key_table_lock, flags); 847 return retval; 848 } 849 850 int register_sysrq_key(int key, struct sysrq_key_op *op_p) 851 { 852 return __sysrq_swap_key_ops(key, op_p, NULL); 853 } 854 EXPORT_SYMBOL(register_sysrq_key); 855 856 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p) 857 { 858 return __sysrq_swap_key_ops(key, NULL, op_p); 859 } 860 EXPORT_SYMBOL(unregister_sysrq_key); 861 862 #ifdef CONFIG_PROC_FS 863 /* 864 * writing 'C' to /proc/sysrq-trigger is like sysrq-C 865 */ 866 static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf, 867 size_t count, loff_t *ppos) 868 { 869 if (count) { 870 char c; 871 872 if (get_user(c, buf)) 873 return -EFAULT; 874 __handle_sysrq(c, false); 875 } 876 877 return count; 878 } 879 880 static const struct file_operations proc_sysrq_trigger_operations = { 881 .write = write_sysrq_trigger, 882 .llseek = noop_llseek, 883 }; 884 885 static void sysrq_init_procfs(void) 886 { 887 if (!proc_create("sysrq-trigger", S_IWUSR, NULL, 888 &proc_sysrq_trigger_operations)) 889 pr_err("Failed to register proc interface\n"); 890 } 891 892 #else 893 894 static inline void sysrq_init_procfs(void) 895 { 896 } 897 898 #endif /* CONFIG_PROC_FS */ 899 900 static int __init sysrq_init(void) 901 { 902 sysrq_init_procfs(); 903 904 if (sysrq_on()) 905 sysrq_register_handler(); 906 907 return 0; 908 } 909 module_init(sysrq_init); 910