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 NULL, /* x */ 456 /* y: May be registered on sparc64 for global register dump */ 457 NULL, /* y */ 458 &sysrq_ftrace_dump_op, /* z */ 459 }; 460 461 /* key2index calculation, -1 on invalid index */ 462 static int sysrq_key_table_key2index(int key) 463 { 464 int retval; 465 466 if ((key >= '0') && (key <= '9')) 467 retval = key - '0'; 468 else if ((key >= 'a') && (key <= 'z')) 469 retval = key + 10 - 'a'; 470 else 471 retval = -1; 472 return retval; 473 } 474 475 /* 476 * get and put functions for the table, exposed to modules. 477 */ 478 struct sysrq_key_op *__sysrq_get_key_op(int key) 479 { 480 struct sysrq_key_op *op_p = NULL; 481 int i; 482 483 i = sysrq_key_table_key2index(key); 484 if (i != -1) 485 op_p = sysrq_key_table[i]; 486 487 return op_p; 488 } 489 490 static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p) 491 { 492 int i = sysrq_key_table_key2index(key); 493 494 if (i != -1) 495 sysrq_key_table[i] = op_p; 496 } 497 498 void __handle_sysrq(int key, bool check_mask) 499 { 500 struct sysrq_key_op *op_p; 501 int orig_log_level; 502 int i; 503 unsigned long flags; 504 505 spin_lock_irqsave(&sysrq_key_table_lock, flags); 506 /* 507 * Raise the apparent loglevel to maximum so that the sysrq header 508 * is shown to provide the user with positive feedback. We do not 509 * simply emit this at KERN_EMERG as that would change message 510 * routing in the consumers of /proc/kmsg. 511 */ 512 orig_log_level = console_loglevel; 513 console_loglevel = 7; 514 printk(KERN_INFO "SysRq : "); 515 516 op_p = __sysrq_get_key_op(key); 517 if (op_p) { 518 /* 519 * Should we check for enabled operations (/proc/sysrq-trigger 520 * should not) and is the invoked operation enabled? 521 */ 522 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) { 523 printk("%s\n", op_p->action_msg); 524 console_loglevel = orig_log_level; 525 op_p->handler(key); 526 } else { 527 printk("This sysrq operation is disabled.\n"); 528 } 529 } else { 530 printk("HELP : "); 531 /* Only print the help msg once per handler */ 532 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) { 533 if (sysrq_key_table[i]) { 534 int j; 535 536 for (j = 0; sysrq_key_table[i] != 537 sysrq_key_table[j]; j++) 538 ; 539 if (j != i) 540 continue; 541 printk("%s ", sysrq_key_table[i]->help_msg); 542 } 543 } 544 printk("\n"); 545 console_loglevel = orig_log_level; 546 } 547 spin_unlock_irqrestore(&sysrq_key_table_lock, flags); 548 } 549 550 void handle_sysrq(int key) 551 { 552 if (sysrq_on()) 553 __handle_sysrq(key, true); 554 } 555 EXPORT_SYMBOL(handle_sysrq); 556 557 #ifdef CONFIG_INPUT 558 559 /* Simple translation table for the SysRq keys */ 560 static const unsigned char sysrq_xlate[KEY_CNT] = 561 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */ 562 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */ 563 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */ 564 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */ 565 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */ 566 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */ 567 "\r\000/"; /* 0x60 - 0x6f */ 568 569 struct sysrq_state { 570 struct input_handle handle; 571 struct work_struct reinject_work; 572 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)]; 573 unsigned int alt; 574 unsigned int alt_use; 575 bool active; 576 bool need_reinject; 577 bool reinjecting; 578 }; 579 580 static void sysrq_reinject_alt_sysrq(struct work_struct *work) 581 { 582 struct sysrq_state *sysrq = 583 container_of(work, struct sysrq_state, reinject_work); 584 struct input_handle *handle = &sysrq->handle; 585 unsigned int alt_code = sysrq->alt_use; 586 587 if (sysrq->need_reinject) { 588 /* we do not want the assignment to be reordered */ 589 sysrq->reinjecting = true; 590 mb(); 591 592 /* Simulate press and release of Alt + SysRq */ 593 input_inject_event(handle, EV_KEY, alt_code, 1); 594 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1); 595 input_inject_event(handle, EV_SYN, SYN_REPORT, 1); 596 597 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0); 598 input_inject_event(handle, EV_KEY, alt_code, 0); 599 input_inject_event(handle, EV_SYN, SYN_REPORT, 1); 600 601 mb(); 602 sysrq->reinjecting = false; 603 } 604 } 605 606 static bool sysrq_filter(struct input_handle *handle, 607 unsigned int type, unsigned int code, int value) 608 { 609 struct sysrq_state *sysrq = handle->private; 610 bool was_active = sysrq->active; 611 bool suppress; 612 613 /* 614 * Do not filter anything if we are in the process of re-injecting 615 * Alt+SysRq combination. 616 */ 617 if (sysrq->reinjecting) 618 return false; 619 620 switch (type) { 621 622 case EV_SYN: 623 suppress = false; 624 break; 625 626 case EV_KEY: 627 switch (code) { 628 629 case KEY_LEFTALT: 630 case KEY_RIGHTALT: 631 if (!value) { 632 /* One of ALTs is being released */ 633 if (sysrq->active && code == sysrq->alt_use) 634 sysrq->active = false; 635 636 sysrq->alt = KEY_RESERVED; 637 638 } else if (value != 2) { 639 sysrq->alt = code; 640 sysrq->need_reinject = false; 641 } 642 break; 643 644 case KEY_SYSRQ: 645 if (value == 1 && sysrq->alt != KEY_RESERVED) { 646 sysrq->active = true; 647 sysrq->alt_use = sysrq->alt; 648 /* 649 * If nothing else will be pressed we'll need 650 * to re-inject Alt-SysRq keysroke. 651 */ 652 sysrq->need_reinject = true; 653 } 654 655 /* 656 * Pretend that sysrq was never pressed at all. This 657 * is needed to properly handle KGDB which will try 658 * to release all keys after exiting debugger. If we 659 * do not clear key bit it KGDB will end up sending 660 * release events for Alt and SysRq, potentially 661 * triggering print screen function. 662 */ 663 if (sysrq->active) 664 clear_bit(KEY_SYSRQ, handle->dev->key); 665 666 break; 667 668 default: 669 if (sysrq->active && value && value != 2) { 670 sysrq->need_reinject = false; 671 __handle_sysrq(sysrq_xlate[code], true); 672 } 673 break; 674 } 675 676 suppress = sysrq->active; 677 678 if (!sysrq->active) { 679 /* 680 * If we are not suppressing key presses keep track of 681 * keyboard state so we can release keys that have been 682 * pressed before entering SysRq mode. 683 */ 684 if (value) 685 set_bit(code, sysrq->key_down); 686 else 687 clear_bit(code, sysrq->key_down); 688 689 if (was_active) 690 schedule_work(&sysrq->reinject_work); 691 692 } else if (value == 0 && 693 test_and_clear_bit(code, sysrq->key_down)) { 694 /* 695 * Pass on release events for keys that was pressed before 696 * entering SysRq mode. 697 */ 698 suppress = false; 699 } 700 break; 701 702 default: 703 suppress = sysrq->active; 704 break; 705 } 706 707 return suppress; 708 } 709 710 static int sysrq_connect(struct input_handler *handler, 711 struct input_dev *dev, 712 const struct input_device_id *id) 713 { 714 struct sysrq_state *sysrq; 715 int error; 716 717 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL); 718 if (!sysrq) 719 return -ENOMEM; 720 721 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq); 722 723 sysrq->handle.dev = dev; 724 sysrq->handle.handler = handler; 725 sysrq->handle.name = "sysrq"; 726 sysrq->handle.private = sysrq; 727 728 error = input_register_handle(&sysrq->handle); 729 if (error) { 730 pr_err("Failed to register input sysrq handler, error %d\n", 731 error); 732 goto err_free; 733 } 734 735 error = input_open_device(&sysrq->handle); 736 if (error) { 737 pr_err("Failed to open input device, error %d\n", error); 738 goto err_unregister; 739 } 740 741 return 0; 742 743 err_unregister: 744 input_unregister_handle(&sysrq->handle); 745 err_free: 746 kfree(sysrq); 747 return error; 748 } 749 750 static void sysrq_disconnect(struct input_handle *handle) 751 { 752 struct sysrq_state *sysrq = handle->private; 753 754 input_close_device(handle); 755 cancel_work_sync(&sysrq->reinject_work); 756 input_unregister_handle(handle); 757 kfree(sysrq); 758 } 759 760 /* 761 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all 762 * keyboards have SysRq key predefined and so user may add it to keymap 763 * later, but we expect all such keyboards to have left alt. 764 */ 765 static const struct input_device_id sysrq_ids[] = { 766 { 767 .flags = INPUT_DEVICE_ID_MATCH_EVBIT | 768 INPUT_DEVICE_ID_MATCH_KEYBIT, 769 .evbit = { BIT_MASK(EV_KEY) }, 770 .keybit = { BIT_MASK(KEY_LEFTALT) }, 771 }, 772 { }, 773 }; 774 775 static struct input_handler sysrq_handler = { 776 .filter = sysrq_filter, 777 .connect = sysrq_connect, 778 .disconnect = sysrq_disconnect, 779 .name = "sysrq", 780 .id_table = sysrq_ids, 781 }; 782 783 static bool sysrq_handler_registered; 784 785 static inline void sysrq_register_handler(void) 786 { 787 int error; 788 789 error = input_register_handler(&sysrq_handler); 790 if (error) 791 pr_err("Failed to register input handler, error %d", error); 792 else 793 sysrq_handler_registered = true; 794 } 795 796 static inline void sysrq_unregister_handler(void) 797 { 798 if (sysrq_handler_registered) { 799 input_unregister_handler(&sysrq_handler); 800 sysrq_handler_registered = false; 801 } 802 } 803 804 #else 805 806 static inline void sysrq_register_handler(void) 807 { 808 } 809 810 static inline void sysrq_unregister_handler(void) 811 { 812 } 813 814 #endif /* CONFIG_INPUT */ 815 816 int sysrq_toggle_support(int enable_mask) 817 { 818 bool was_enabled = sysrq_on(); 819 820 sysrq_enabled = enable_mask; 821 822 if (was_enabled != sysrq_on()) { 823 if (sysrq_on()) 824 sysrq_register_handler(); 825 else 826 sysrq_unregister_handler(); 827 } 828 829 return 0; 830 } 831 832 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p, 833 struct sysrq_key_op *remove_op_p) 834 { 835 int retval; 836 unsigned long flags; 837 838 spin_lock_irqsave(&sysrq_key_table_lock, flags); 839 if (__sysrq_get_key_op(key) == remove_op_p) { 840 __sysrq_put_key_op(key, insert_op_p); 841 retval = 0; 842 } else { 843 retval = -1; 844 } 845 spin_unlock_irqrestore(&sysrq_key_table_lock, flags); 846 return retval; 847 } 848 849 int register_sysrq_key(int key, struct sysrq_key_op *op_p) 850 { 851 return __sysrq_swap_key_ops(key, op_p, NULL); 852 } 853 EXPORT_SYMBOL(register_sysrq_key); 854 855 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p) 856 { 857 return __sysrq_swap_key_ops(key, NULL, op_p); 858 } 859 EXPORT_SYMBOL(unregister_sysrq_key); 860 861 #ifdef CONFIG_PROC_FS 862 /* 863 * writing 'C' to /proc/sysrq-trigger is like sysrq-C 864 */ 865 static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf, 866 size_t count, loff_t *ppos) 867 { 868 if (count) { 869 char c; 870 871 if (get_user(c, buf)) 872 return -EFAULT; 873 __handle_sysrq(c, false); 874 } 875 876 return count; 877 } 878 879 static const struct file_operations proc_sysrq_trigger_operations = { 880 .write = write_sysrq_trigger, 881 .llseek = noop_llseek, 882 }; 883 884 static void sysrq_init_procfs(void) 885 { 886 if (!proc_create("sysrq-trigger", S_IWUSR, NULL, 887 &proc_sysrq_trigger_operations)) 888 pr_err("Failed to register proc interface\n"); 889 } 890 891 #else 892 893 static inline void sysrq_init_procfs(void) 894 { 895 } 896 897 #endif /* CONFIG_PROC_FS */ 898 899 static int __init sysrq_init(void) 900 { 901 sysrq_init_procfs(); 902 903 if (sysrq_on()) 904 sysrq_register_handler(); 905 906 return 0; 907 } 908 module_init(sysrq_init); 909