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(first_online_node, GFP_KERNEL), GFP_KERNEL, 350 0, NULL, true); 351 } 352 353 static DECLARE_WORK(moom_work, moom_callback); 354 355 static void sysrq_handle_moom(int key) 356 { 357 schedule_work(&moom_work); 358 } 359 static struct sysrq_key_op sysrq_moom_op = { 360 .handler = sysrq_handle_moom, 361 .help_msg = "memory-full-oom-kill(F)", 362 .action_msg = "Manual OOM execution", 363 .enable_mask = SYSRQ_ENABLE_SIGNAL, 364 }; 365 366 #ifdef CONFIG_BLOCK 367 static void sysrq_handle_thaw(int key) 368 { 369 emergency_thaw_all(); 370 } 371 static struct sysrq_key_op sysrq_thaw_op = { 372 .handler = sysrq_handle_thaw, 373 .help_msg = "thaw-filesystems(J)", 374 .action_msg = "Emergency Thaw of all frozen filesystems", 375 .enable_mask = SYSRQ_ENABLE_SIGNAL, 376 }; 377 #endif 378 379 static void sysrq_handle_kill(int key) 380 { 381 send_sig_all(SIGKILL); 382 console_loglevel = 8; 383 } 384 static struct sysrq_key_op sysrq_kill_op = { 385 .handler = sysrq_handle_kill, 386 .help_msg = "kill-all-tasks(I)", 387 .action_msg = "Kill All Tasks", 388 .enable_mask = SYSRQ_ENABLE_SIGNAL, 389 }; 390 391 static void sysrq_handle_unrt(int key) 392 { 393 normalize_rt_tasks(); 394 } 395 static struct sysrq_key_op sysrq_unrt_op = { 396 .handler = sysrq_handle_unrt, 397 .help_msg = "nice-all-RT-tasks(N)", 398 .action_msg = "Nice All RT Tasks", 399 .enable_mask = SYSRQ_ENABLE_RTNICE, 400 }; 401 402 /* Key Operations table and lock */ 403 static DEFINE_SPINLOCK(sysrq_key_table_lock); 404 405 static struct sysrq_key_op *sysrq_key_table[36] = { 406 &sysrq_loglevel_op, /* 0 */ 407 &sysrq_loglevel_op, /* 1 */ 408 &sysrq_loglevel_op, /* 2 */ 409 &sysrq_loglevel_op, /* 3 */ 410 &sysrq_loglevel_op, /* 4 */ 411 &sysrq_loglevel_op, /* 5 */ 412 &sysrq_loglevel_op, /* 6 */ 413 &sysrq_loglevel_op, /* 7 */ 414 &sysrq_loglevel_op, /* 8 */ 415 &sysrq_loglevel_op, /* 9 */ 416 417 /* 418 * a: Don't use for system provided sysrqs, it is handled specially on 419 * sparc and will never arrive. 420 */ 421 NULL, /* a */ 422 &sysrq_reboot_op, /* b */ 423 &sysrq_crash_op, /* c & ibm_emac driver debug */ 424 &sysrq_showlocks_op, /* d */ 425 &sysrq_term_op, /* e */ 426 &sysrq_moom_op, /* f */ 427 /* g: May be registered for the kernel debugger */ 428 NULL, /* g */ 429 NULL, /* h - reserved for help */ 430 &sysrq_kill_op, /* i */ 431 #ifdef CONFIG_BLOCK 432 &sysrq_thaw_op, /* j */ 433 #else 434 NULL, /* j */ 435 #endif 436 &sysrq_SAK_op, /* k */ 437 #ifdef CONFIG_SMP 438 &sysrq_showallcpus_op, /* l */ 439 #else 440 NULL, /* l */ 441 #endif 442 &sysrq_showmem_op, /* m */ 443 &sysrq_unrt_op, /* n */ 444 /* o: This will often be registered as 'Off' at init time */ 445 NULL, /* o */ 446 &sysrq_showregs_op, /* p */ 447 &sysrq_show_timers_op, /* q */ 448 &sysrq_unraw_op, /* r */ 449 &sysrq_sync_op, /* s */ 450 &sysrq_showstate_op, /* t */ 451 &sysrq_mountro_op, /* u */ 452 /* v: May be registered for frame buffer console restore */ 453 NULL, /* v */ 454 &sysrq_showstate_blocked_op, /* w */ 455 /* x: May be registered on ppc/powerpc for xmon */ 456 /* x: May be registered on sparc64 for global PMU dump */ 457 NULL, /* x */ 458 /* y: May be registered on sparc64 for global register dump */ 459 NULL, /* y */ 460 &sysrq_ftrace_dump_op, /* z */ 461 }; 462 463 /* key2index calculation, -1 on invalid index */ 464 static int sysrq_key_table_key2index(int key) 465 { 466 int retval; 467 468 if ((key >= '0') && (key <= '9')) 469 retval = key - '0'; 470 else if ((key >= 'a') && (key <= 'z')) 471 retval = key + 10 - 'a'; 472 else 473 retval = -1; 474 return retval; 475 } 476 477 /* 478 * get and put functions for the table, exposed to modules. 479 */ 480 struct sysrq_key_op *__sysrq_get_key_op(int key) 481 { 482 struct sysrq_key_op *op_p = NULL; 483 int i; 484 485 i = sysrq_key_table_key2index(key); 486 if (i != -1) 487 op_p = sysrq_key_table[i]; 488 489 return op_p; 490 } 491 492 static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p) 493 { 494 int i = sysrq_key_table_key2index(key); 495 496 if (i != -1) 497 sysrq_key_table[i] = op_p; 498 } 499 500 void __handle_sysrq(int key, bool check_mask) 501 { 502 struct sysrq_key_op *op_p; 503 int orig_log_level; 504 int i; 505 unsigned long flags; 506 507 spin_lock_irqsave(&sysrq_key_table_lock, flags); 508 /* 509 * Raise the apparent loglevel to maximum so that the sysrq header 510 * is shown to provide the user with positive feedback. We do not 511 * simply emit this at KERN_EMERG as that would change message 512 * routing in the consumers of /proc/kmsg. 513 */ 514 orig_log_level = console_loglevel; 515 console_loglevel = 7; 516 printk(KERN_INFO "SysRq : "); 517 518 op_p = __sysrq_get_key_op(key); 519 if (op_p) { 520 /* 521 * Should we check for enabled operations (/proc/sysrq-trigger 522 * should not) and is the invoked operation enabled? 523 */ 524 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) { 525 printk("%s\n", op_p->action_msg); 526 console_loglevel = orig_log_level; 527 op_p->handler(key); 528 } else { 529 printk("This sysrq operation is disabled.\n"); 530 } 531 } else { 532 printk("HELP : "); 533 /* Only print the help msg once per handler */ 534 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) { 535 if (sysrq_key_table[i]) { 536 int j; 537 538 for (j = 0; sysrq_key_table[i] != 539 sysrq_key_table[j]; j++) 540 ; 541 if (j != i) 542 continue; 543 printk("%s ", sysrq_key_table[i]->help_msg); 544 } 545 } 546 printk("\n"); 547 console_loglevel = orig_log_level; 548 } 549 spin_unlock_irqrestore(&sysrq_key_table_lock, flags); 550 } 551 552 void handle_sysrq(int key) 553 { 554 if (sysrq_on()) 555 __handle_sysrq(key, true); 556 } 557 EXPORT_SYMBOL(handle_sysrq); 558 559 #ifdef CONFIG_INPUT 560 561 /* Simple translation table for the SysRq keys */ 562 static const unsigned char sysrq_xlate[KEY_CNT] = 563 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */ 564 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */ 565 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */ 566 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */ 567 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */ 568 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */ 569 "\r\000/"; /* 0x60 - 0x6f */ 570 571 struct sysrq_state { 572 struct input_handle handle; 573 struct work_struct reinject_work; 574 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)]; 575 unsigned int alt; 576 unsigned int alt_use; 577 bool active; 578 bool need_reinject; 579 bool reinjecting; 580 }; 581 582 static void sysrq_reinject_alt_sysrq(struct work_struct *work) 583 { 584 struct sysrq_state *sysrq = 585 container_of(work, struct sysrq_state, reinject_work); 586 struct input_handle *handle = &sysrq->handle; 587 unsigned int alt_code = sysrq->alt_use; 588 589 if (sysrq->need_reinject) { 590 /* we do not want the assignment to be reordered */ 591 sysrq->reinjecting = true; 592 mb(); 593 594 /* Simulate press and release of Alt + SysRq */ 595 input_inject_event(handle, EV_KEY, alt_code, 1); 596 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1); 597 input_inject_event(handle, EV_SYN, SYN_REPORT, 1); 598 599 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0); 600 input_inject_event(handle, EV_KEY, alt_code, 0); 601 input_inject_event(handle, EV_SYN, SYN_REPORT, 1); 602 603 mb(); 604 sysrq->reinjecting = false; 605 } 606 } 607 608 static bool sysrq_filter(struct input_handle *handle, 609 unsigned int type, unsigned int code, int value) 610 { 611 struct sysrq_state *sysrq = handle->private; 612 bool was_active = sysrq->active; 613 bool suppress; 614 615 /* 616 * Do not filter anything if we are in the process of re-injecting 617 * Alt+SysRq combination. 618 */ 619 if (sysrq->reinjecting) 620 return false; 621 622 switch (type) { 623 624 case EV_SYN: 625 suppress = false; 626 break; 627 628 case EV_KEY: 629 switch (code) { 630 631 case KEY_LEFTALT: 632 case KEY_RIGHTALT: 633 if (!value) { 634 /* One of ALTs is being released */ 635 if (sysrq->active && code == sysrq->alt_use) 636 sysrq->active = false; 637 638 sysrq->alt = KEY_RESERVED; 639 640 } else if (value != 2) { 641 sysrq->alt = code; 642 sysrq->need_reinject = false; 643 } 644 break; 645 646 case KEY_SYSRQ: 647 if (value == 1 && sysrq->alt != KEY_RESERVED) { 648 sysrq->active = true; 649 sysrq->alt_use = sysrq->alt; 650 /* 651 * If nothing else will be pressed we'll need 652 * to re-inject Alt-SysRq keysroke. 653 */ 654 sysrq->need_reinject = true; 655 } 656 657 /* 658 * Pretend that sysrq was never pressed at all. This 659 * is needed to properly handle KGDB which will try 660 * to release all keys after exiting debugger. If we 661 * do not clear key bit it KGDB will end up sending 662 * release events for Alt and SysRq, potentially 663 * triggering print screen function. 664 */ 665 if (sysrq->active) 666 clear_bit(KEY_SYSRQ, handle->dev->key); 667 668 break; 669 670 default: 671 if (sysrq->active && value && value != 2) { 672 sysrq->need_reinject = false; 673 __handle_sysrq(sysrq_xlate[code], true); 674 } 675 break; 676 } 677 678 suppress = sysrq->active; 679 680 if (!sysrq->active) { 681 /* 682 * If we are not suppressing key presses keep track of 683 * keyboard state so we can release keys that have been 684 * pressed before entering SysRq mode. 685 */ 686 if (value) 687 set_bit(code, sysrq->key_down); 688 else 689 clear_bit(code, sysrq->key_down); 690 691 if (was_active) 692 schedule_work(&sysrq->reinject_work); 693 694 } else if (value == 0 && 695 test_and_clear_bit(code, sysrq->key_down)) { 696 /* 697 * Pass on release events for keys that was pressed before 698 * entering SysRq mode. 699 */ 700 suppress = false; 701 } 702 break; 703 704 default: 705 suppress = sysrq->active; 706 break; 707 } 708 709 return suppress; 710 } 711 712 static int sysrq_connect(struct input_handler *handler, 713 struct input_dev *dev, 714 const struct input_device_id *id) 715 { 716 struct sysrq_state *sysrq; 717 int error; 718 719 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL); 720 if (!sysrq) 721 return -ENOMEM; 722 723 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq); 724 725 sysrq->handle.dev = dev; 726 sysrq->handle.handler = handler; 727 sysrq->handle.name = "sysrq"; 728 sysrq->handle.private = sysrq; 729 730 error = input_register_handle(&sysrq->handle); 731 if (error) { 732 pr_err("Failed to register input sysrq handler, error %d\n", 733 error); 734 goto err_free; 735 } 736 737 error = input_open_device(&sysrq->handle); 738 if (error) { 739 pr_err("Failed to open input device, error %d\n", error); 740 goto err_unregister; 741 } 742 743 return 0; 744 745 err_unregister: 746 input_unregister_handle(&sysrq->handle); 747 err_free: 748 kfree(sysrq); 749 return error; 750 } 751 752 static void sysrq_disconnect(struct input_handle *handle) 753 { 754 struct sysrq_state *sysrq = handle->private; 755 756 input_close_device(handle); 757 cancel_work_sync(&sysrq->reinject_work); 758 input_unregister_handle(handle); 759 kfree(sysrq); 760 } 761 762 /* 763 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all 764 * keyboards have SysRq key predefined and so user may add it to keymap 765 * later, but we expect all such keyboards to have left alt. 766 */ 767 static const struct input_device_id sysrq_ids[] = { 768 { 769 .flags = INPUT_DEVICE_ID_MATCH_EVBIT | 770 INPUT_DEVICE_ID_MATCH_KEYBIT, 771 .evbit = { BIT_MASK(EV_KEY) }, 772 .keybit = { BIT_MASK(KEY_LEFTALT) }, 773 }, 774 { }, 775 }; 776 777 static struct input_handler sysrq_handler = { 778 .filter = sysrq_filter, 779 .connect = sysrq_connect, 780 .disconnect = sysrq_disconnect, 781 .name = "sysrq", 782 .id_table = sysrq_ids, 783 }; 784 785 static bool sysrq_handler_registered; 786 787 static inline void sysrq_register_handler(void) 788 { 789 int error; 790 791 error = input_register_handler(&sysrq_handler); 792 if (error) 793 pr_err("Failed to register input handler, error %d", error); 794 else 795 sysrq_handler_registered = true; 796 } 797 798 static inline void sysrq_unregister_handler(void) 799 { 800 if (sysrq_handler_registered) { 801 input_unregister_handler(&sysrq_handler); 802 sysrq_handler_registered = false; 803 } 804 } 805 806 #else 807 808 static inline void sysrq_register_handler(void) 809 { 810 } 811 812 static inline void sysrq_unregister_handler(void) 813 { 814 } 815 816 #endif /* CONFIG_INPUT */ 817 818 int sysrq_toggle_support(int enable_mask) 819 { 820 bool was_enabled = sysrq_on(); 821 822 sysrq_enabled = enable_mask; 823 824 if (was_enabled != sysrq_on()) { 825 if (sysrq_on()) 826 sysrq_register_handler(); 827 else 828 sysrq_unregister_handler(); 829 } 830 831 return 0; 832 } 833 834 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p, 835 struct sysrq_key_op *remove_op_p) 836 { 837 int retval; 838 unsigned long flags; 839 840 spin_lock_irqsave(&sysrq_key_table_lock, flags); 841 if (__sysrq_get_key_op(key) == remove_op_p) { 842 __sysrq_put_key_op(key, insert_op_p); 843 retval = 0; 844 } else { 845 retval = -1; 846 } 847 spin_unlock_irqrestore(&sysrq_key_table_lock, flags); 848 return retval; 849 } 850 851 int register_sysrq_key(int key, struct sysrq_key_op *op_p) 852 { 853 return __sysrq_swap_key_ops(key, op_p, NULL); 854 } 855 EXPORT_SYMBOL(register_sysrq_key); 856 857 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p) 858 { 859 return __sysrq_swap_key_ops(key, NULL, op_p); 860 } 861 EXPORT_SYMBOL(unregister_sysrq_key); 862 863 #ifdef CONFIG_PROC_FS 864 /* 865 * writing 'C' to /proc/sysrq-trigger is like sysrq-C 866 */ 867 static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf, 868 size_t count, loff_t *ppos) 869 { 870 if (count) { 871 char c; 872 873 if (get_user(c, buf)) 874 return -EFAULT; 875 __handle_sysrq(c, false); 876 } 877 878 return count; 879 } 880 881 static const struct file_operations proc_sysrq_trigger_operations = { 882 .write = write_sysrq_trigger, 883 .llseek = noop_llseek, 884 }; 885 886 static void sysrq_init_procfs(void) 887 { 888 if (!proc_create("sysrq-trigger", S_IWUSR, NULL, 889 &proc_sysrq_trigger_operations)) 890 pr_err("Failed to register proc interface\n"); 891 } 892 893 #else 894 895 static inline void sysrq_init_procfs(void) 896 { 897 } 898 899 #endif /* CONFIG_PROC_FS */ 900 901 static int __init sysrq_init(void) 902 { 903 sysrq_init_procfs(); 904 905 if (sysrq_on()) 906 sysrq_register_handler(); 907 908 return 0; 909 } 910 module_init(sysrq_init); 911