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/sched/rt.h> 19 #include <linux/interrupt.h> 20 #include <linux/mm.h> 21 #include <linux/fs.h> 22 #include <linux/mount.h> 23 #include <linux/kdev_t.h> 24 #include <linux/major.h> 25 #include <linux/reboot.h> 26 #include <linux/sysrq.h> 27 #include <linux/kbd_kern.h> 28 #include <linux/proc_fs.h> 29 #include <linux/nmi.h> 30 #include <linux/quotaops.h> 31 #include <linux/perf_event.h> 32 #include <linux/kernel.h> 33 #include <linux/module.h> 34 #include <linux/suspend.h> 35 #include <linux/writeback.h> 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 #include <linux/uaccess.h> 45 #include <linux/moduleparam.h> 46 #include <linux/jiffies.h> 47 48 #include <asm/ptrace.h> 49 #include <asm/irq_regs.h> 50 51 /* Whether we react on sysrq keys or just ignore them */ 52 static int __read_mostly sysrq_enabled = SYSRQ_DEFAULT_ENABLE; 53 static bool __read_mostly sysrq_always_enabled; 54 55 unsigned short platform_sysrq_reset_seq[] __weak = { KEY_RESERVED }; 56 int sysrq_reset_downtime_ms __weak; 57 58 static bool sysrq_on(void) 59 { 60 return sysrq_enabled || sysrq_always_enabled; 61 } 62 63 /* 64 * A value of 1 means 'all', other nonzero values are an op mask: 65 */ 66 static bool sysrq_on_mask(int mask) 67 { 68 return sysrq_always_enabled || 69 sysrq_enabled == 1 || 70 (sysrq_enabled & mask); 71 } 72 73 static int __init sysrq_always_enabled_setup(char *str) 74 { 75 sysrq_always_enabled = true; 76 pr_info("sysrq always enabled.\n"); 77 78 return 1; 79 } 80 81 __setup("sysrq_always_enabled", sysrq_always_enabled_setup); 82 83 84 static void sysrq_handle_loglevel(int key) 85 { 86 int i; 87 88 i = key - '0'; 89 console_loglevel = 7; 90 printk("Loglevel set to %d\n", i); 91 console_loglevel = i; 92 } 93 static struct sysrq_key_op sysrq_loglevel_op = { 94 .handler = sysrq_handle_loglevel, 95 .help_msg = "loglevel(0-9)", 96 .action_msg = "Changing Loglevel", 97 .enable_mask = SYSRQ_ENABLE_LOG, 98 }; 99 100 #ifdef CONFIG_VT 101 static void sysrq_handle_SAK(int key) 102 { 103 struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work; 104 schedule_work(SAK_work); 105 } 106 static struct sysrq_key_op sysrq_SAK_op = { 107 .handler = sysrq_handle_SAK, 108 .help_msg = "sak(k)", 109 .action_msg = "SAK", 110 .enable_mask = SYSRQ_ENABLE_KEYBOARD, 111 }; 112 #else 113 #define sysrq_SAK_op (*(struct sysrq_key_op *)NULL) 114 #endif 115 116 #ifdef CONFIG_VT 117 static void sysrq_handle_unraw(int key) 118 { 119 vt_reset_unicode(fg_console); 120 } 121 122 static struct sysrq_key_op sysrq_unraw_op = { 123 .handler = sysrq_handle_unraw, 124 .help_msg = "unraw(r)", 125 .action_msg = "Keyboard mode set to system default", 126 .enable_mask = SYSRQ_ENABLE_KEYBOARD, 127 }; 128 #else 129 #define sysrq_unraw_op (*(struct sysrq_key_op *)NULL) 130 #endif /* CONFIG_VT */ 131 132 static void sysrq_handle_crash(int key) 133 { 134 char *killer = NULL; 135 136 panic_on_oops = 1; /* force panic */ 137 wmb(); 138 *killer = 1; 139 } 140 static struct sysrq_key_op sysrq_crash_op = { 141 .handler = sysrq_handle_crash, 142 .help_msg = "crash(c)", 143 .action_msg = "Trigger a crash", 144 .enable_mask = SYSRQ_ENABLE_DUMP, 145 }; 146 147 static void sysrq_handle_reboot(int key) 148 { 149 lockdep_off(); 150 local_irq_enable(); 151 emergency_restart(); 152 } 153 static struct sysrq_key_op sysrq_reboot_op = { 154 .handler = sysrq_handle_reboot, 155 .help_msg = "reboot(b)", 156 .action_msg = "Resetting", 157 .enable_mask = SYSRQ_ENABLE_BOOT, 158 }; 159 160 static void sysrq_handle_sync(int key) 161 { 162 emergency_sync(); 163 } 164 static struct sysrq_key_op sysrq_sync_op = { 165 .handler = sysrq_handle_sync, 166 .help_msg = "sync(s)", 167 .action_msg = "Emergency Sync", 168 .enable_mask = SYSRQ_ENABLE_SYNC, 169 }; 170 171 static void sysrq_handle_show_timers(int key) 172 { 173 sysrq_timer_list_show(); 174 } 175 176 static struct sysrq_key_op sysrq_show_timers_op = { 177 .handler = sysrq_handle_show_timers, 178 .help_msg = "show-all-timers(q)", 179 .action_msg = "Show clockevent devices & pending hrtimers (no others)", 180 }; 181 182 static void sysrq_handle_mountro(int key) 183 { 184 emergency_remount(); 185 } 186 static struct sysrq_key_op sysrq_mountro_op = { 187 .handler = sysrq_handle_mountro, 188 .help_msg = "unmount(u)", 189 .action_msg = "Emergency Remount R/O", 190 .enable_mask = SYSRQ_ENABLE_REMOUNT, 191 }; 192 193 #ifdef CONFIG_LOCKDEP 194 static void sysrq_handle_showlocks(int key) 195 { 196 debug_show_all_locks(); 197 } 198 199 static struct sysrq_key_op sysrq_showlocks_op = { 200 .handler = sysrq_handle_showlocks, 201 .help_msg = "show-all-locks(d)", 202 .action_msg = "Show Locks Held", 203 }; 204 #else 205 #define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL) 206 #endif 207 208 #ifdef CONFIG_SMP 209 static DEFINE_SPINLOCK(show_lock); 210 211 static void showacpu(void *dummy) 212 { 213 unsigned long flags; 214 215 /* Idle CPUs have no interesting backtrace. */ 216 if (idle_cpu(smp_processor_id())) 217 return; 218 219 spin_lock_irqsave(&show_lock, flags); 220 printk(KERN_INFO "CPU%d:\n", smp_processor_id()); 221 show_stack(NULL, NULL); 222 spin_unlock_irqrestore(&show_lock, flags); 223 } 224 225 static void sysrq_showregs_othercpus(struct work_struct *dummy) 226 { 227 smp_call_function(showacpu, NULL, 0); 228 } 229 230 static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus); 231 232 static void sysrq_handle_showallcpus(int key) 233 { 234 /* 235 * Fall back to the workqueue based printing if the 236 * backtrace printing did not succeed or the 237 * architecture has no support for it: 238 */ 239 if (!trigger_all_cpu_backtrace()) { 240 struct pt_regs *regs = get_irq_regs(); 241 242 if (regs) { 243 printk(KERN_INFO "CPU%d:\n", smp_processor_id()); 244 show_regs(regs); 245 } 246 schedule_work(&sysrq_showallcpus); 247 } 248 } 249 250 static struct sysrq_key_op sysrq_showallcpus_op = { 251 .handler = sysrq_handle_showallcpus, 252 .help_msg = "show-backtrace-all-active-cpus(l)", 253 .action_msg = "Show backtrace of all active CPUs", 254 .enable_mask = SYSRQ_ENABLE_DUMP, 255 }; 256 #endif 257 258 static void sysrq_handle_showregs(int key) 259 { 260 struct pt_regs *regs = get_irq_regs(); 261 if (regs) 262 show_regs(regs); 263 perf_event_print_debug(); 264 } 265 static struct sysrq_key_op sysrq_showregs_op = { 266 .handler = sysrq_handle_showregs, 267 .help_msg = "show-registers(p)", 268 .action_msg = "Show Regs", 269 .enable_mask = SYSRQ_ENABLE_DUMP, 270 }; 271 272 static void sysrq_handle_showstate(int key) 273 { 274 show_state(); 275 } 276 static struct sysrq_key_op sysrq_showstate_op = { 277 .handler = sysrq_handle_showstate, 278 .help_msg = "show-task-states(t)", 279 .action_msg = "Show State", 280 .enable_mask = SYSRQ_ENABLE_DUMP, 281 }; 282 283 static void sysrq_handle_showstate_blocked(int key) 284 { 285 show_state_filter(TASK_UNINTERRUPTIBLE); 286 } 287 static struct sysrq_key_op sysrq_showstate_blocked_op = { 288 .handler = sysrq_handle_showstate_blocked, 289 .help_msg = "show-blocked-tasks(w)", 290 .action_msg = "Show Blocked State", 291 .enable_mask = SYSRQ_ENABLE_DUMP, 292 }; 293 294 #ifdef CONFIG_TRACING 295 #include <linux/ftrace.h> 296 297 static void sysrq_ftrace_dump(int key) 298 { 299 ftrace_dump(DUMP_ALL); 300 } 301 static struct sysrq_key_op sysrq_ftrace_dump_op = { 302 .handler = sysrq_ftrace_dump, 303 .help_msg = "dump-ftrace-buffer(z)", 304 .action_msg = "Dump ftrace buffer", 305 .enable_mask = SYSRQ_ENABLE_DUMP, 306 }; 307 #else 308 #define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL) 309 #endif 310 311 static void sysrq_handle_showmem(int key) 312 { 313 show_mem(0); 314 } 315 static struct sysrq_key_op sysrq_showmem_op = { 316 .handler = sysrq_handle_showmem, 317 .help_msg = "show-memory-usage(m)", 318 .action_msg = "Show Memory", 319 .enable_mask = SYSRQ_ENABLE_DUMP, 320 }; 321 322 /* 323 * Signal sysrq helper function. Sends a signal to all user processes. 324 */ 325 static void send_sig_all(int sig) 326 { 327 struct task_struct *p; 328 329 read_lock(&tasklist_lock); 330 for_each_process(p) { 331 if (p->flags & PF_KTHREAD) 332 continue; 333 if (is_global_init(p)) 334 continue; 335 336 do_send_sig_info(sig, SEND_SIG_FORCED, p, true); 337 } 338 read_unlock(&tasklist_lock); 339 } 340 341 static void sysrq_handle_term(int key) 342 { 343 send_sig_all(SIGTERM); 344 console_loglevel = 8; 345 } 346 static struct sysrq_key_op sysrq_term_op = { 347 .handler = sysrq_handle_term, 348 .help_msg = "terminate-all-tasks(e)", 349 .action_msg = "Terminate All Tasks", 350 .enable_mask = SYSRQ_ENABLE_SIGNAL, 351 }; 352 353 static void moom_callback(struct work_struct *ignored) 354 { 355 out_of_memory(node_zonelist(first_online_node, GFP_KERNEL), GFP_KERNEL, 356 0, NULL, true); 357 } 358 359 static DECLARE_WORK(moom_work, moom_callback); 360 361 static void sysrq_handle_moom(int key) 362 { 363 schedule_work(&moom_work); 364 } 365 static struct sysrq_key_op sysrq_moom_op = { 366 .handler = sysrq_handle_moom, 367 .help_msg = "memory-full-oom-kill(f)", 368 .action_msg = "Manual OOM execution", 369 .enable_mask = SYSRQ_ENABLE_SIGNAL, 370 }; 371 372 #ifdef CONFIG_BLOCK 373 static void sysrq_handle_thaw(int key) 374 { 375 emergency_thaw_all(); 376 } 377 static struct sysrq_key_op sysrq_thaw_op = { 378 .handler = sysrq_handle_thaw, 379 .help_msg = "thaw-filesystems(j)", 380 .action_msg = "Emergency Thaw of all frozen filesystems", 381 .enable_mask = SYSRQ_ENABLE_SIGNAL, 382 }; 383 #endif 384 385 static void sysrq_handle_kill(int key) 386 { 387 send_sig_all(SIGKILL); 388 console_loglevel = 8; 389 } 390 static struct sysrq_key_op sysrq_kill_op = { 391 .handler = sysrq_handle_kill, 392 .help_msg = "kill-all-tasks(i)", 393 .action_msg = "Kill All Tasks", 394 .enable_mask = SYSRQ_ENABLE_SIGNAL, 395 }; 396 397 static void sysrq_handle_unrt(int key) 398 { 399 normalize_rt_tasks(); 400 } 401 static struct sysrq_key_op sysrq_unrt_op = { 402 .handler = sysrq_handle_unrt, 403 .help_msg = "nice-all-RT-tasks(n)", 404 .action_msg = "Nice All RT Tasks", 405 .enable_mask = SYSRQ_ENABLE_RTNICE, 406 }; 407 408 /* Key Operations table and lock */ 409 static DEFINE_SPINLOCK(sysrq_key_table_lock); 410 411 static struct sysrq_key_op *sysrq_key_table[36] = { 412 &sysrq_loglevel_op, /* 0 */ 413 &sysrq_loglevel_op, /* 1 */ 414 &sysrq_loglevel_op, /* 2 */ 415 &sysrq_loglevel_op, /* 3 */ 416 &sysrq_loglevel_op, /* 4 */ 417 &sysrq_loglevel_op, /* 5 */ 418 &sysrq_loglevel_op, /* 6 */ 419 &sysrq_loglevel_op, /* 7 */ 420 &sysrq_loglevel_op, /* 8 */ 421 &sysrq_loglevel_op, /* 9 */ 422 423 /* 424 * a: Don't use for system provided sysrqs, it is handled specially on 425 * sparc and will never arrive. 426 */ 427 NULL, /* a */ 428 &sysrq_reboot_op, /* b */ 429 &sysrq_crash_op, /* c & ibm_emac driver debug */ 430 &sysrq_showlocks_op, /* d */ 431 &sysrq_term_op, /* e */ 432 &sysrq_moom_op, /* f */ 433 /* g: May be registered for the kernel debugger */ 434 NULL, /* g */ 435 NULL, /* h - reserved for help */ 436 &sysrq_kill_op, /* i */ 437 #ifdef CONFIG_BLOCK 438 &sysrq_thaw_op, /* j */ 439 #else 440 NULL, /* j */ 441 #endif 442 &sysrq_SAK_op, /* k */ 443 #ifdef CONFIG_SMP 444 &sysrq_showallcpus_op, /* l */ 445 #else 446 NULL, /* l */ 447 #endif 448 &sysrq_showmem_op, /* m */ 449 &sysrq_unrt_op, /* n */ 450 /* o: This will often be registered as 'Off' at init time */ 451 NULL, /* o */ 452 &sysrq_showregs_op, /* p */ 453 &sysrq_show_timers_op, /* q */ 454 &sysrq_unraw_op, /* r */ 455 &sysrq_sync_op, /* s */ 456 &sysrq_showstate_op, /* t */ 457 &sysrq_mountro_op, /* u */ 458 /* v: May be registered for frame buffer console restore */ 459 NULL, /* v */ 460 &sysrq_showstate_blocked_op, /* w */ 461 /* x: May be registered on ppc/powerpc for xmon */ 462 /* x: May be registered on sparc64 for global PMU dump */ 463 NULL, /* x */ 464 /* y: May be registered on sparc64 for global register dump */ 465 NULL, /* y */ 466 &sysrq_ftrace_dump_op, /* z */ 467 }; 468 469 /* key2index calculation, -1 on invalid index */ 470 static int sysrq_key_table_key2index(int key) 471 { 472 int retval; 473 474 if ((key >= '0') && (key <= '9')) 475 retval = key - '0'; 476 else if ((key >= 'a') && (key <= 'z')) 477 retval = key + 10 - 'a'; 478 else 479 retval = -1; 480 return retval; 481 } 482 483 /* 484 * get and put functions for the table, exposed to modules. 485 */ 486 struct sysrq_key_op *__sysrq_get_key_op(int key) 487 { 488 struct sysrq_key_op *op_p = NULL; 489 int i; 490 491 i = sysrq_key_table_key2index(key); 492 if (i != -1) 493 op_p = sysrq_key_table[i]; 494 495 return op_p; 496 } 497 498 static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p) 499 { 500 int i = sysrq_key_table_key2index(key); 501 502 if (i != -1) 503 sysrq_key_table[i] = op_p; 504 } 505 506 void __handle_sysrq(int key, bool check_mask) 507 { 508 struct sysrq_key_op *op_p; 509 int orig_log_level; 510 int i; 511 unsigned long flags; 512 513 spin_lock_irqsave(&sysrq_key_table_lock, flags); 514 /* 515 * Raise the apparent loglevel to maximum so that the sysrq header 516 * is shown to provide the user with positive feedback. We do not 517 * simply emit this at KERN_EMERG as that would change message 518 * routing in the consumers of /proc/kmsg. 519 */ 520 orig_log_level = console_loglevel; 521 console_loglevel = 7; 522 printk(KERN_INFO "SysRq : "); 523 524 op_p = __sysrq_get_key_op(key); 525 if (op_p) { 526 /* 527 * Should we check for enabled operations (/proc/sysrq-trigger 528 * should not) and is the invoked operation enabled? 529 */ 530 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) { 531 printk("%s\n", op_p->action_msg); 532 console_loglevel = orig_log_level; 533 op_p->handler(key); 534 } else { 535 printk("This sysrq operation is disabled.\n"); 536 } 537 } else { 538 printk("HELP : "); 539 /* Only print the help msg once per handler */ 540 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) { 541 if (sysrq_key_table[i]) { 542 int j; 543 544 for (j = 0; sysrq_key_table[i] != 545 sysrq_key_table[j]; j++) 546 ; 547 if (j != i) 548 continue; 549 printk("%s ", sysrq_key_table[i]->help_msg); 550 } 551 } 552 printk("\n"); 553 console_loglevel = orig_log_level; 554 } 555 spin_unlock_irqrestore(&sysrq_key_table_lock, flags); 556 } 557 558 void handle_sysrq(int key) 559 { 560 if (sysrq_on()) 561 __handle_sysrq(key, true); 562 } 563 EXPORT_SYMBOL(handle_sysrq); 564 565 #ifdef CONFIG_INPUT 566 567 /* Simple translation table for the SysRq keys */ 568 static const unsigned char sysrq_xlate[KEY_CNT] = 569 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */ 570 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */ 571 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */ 572 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */ 573 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */ 574 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */ 575 "\r\000/"; /* 0x60 - 0x6f */ 576 577 struct sysrq_state { 578 struct input_handle handle; 579 struct work_struct reinject_work; 580 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)]; 581 unsigned int alt; 582 unsigned int alt_use; 583 bool active; 584 bool need_reinject; 585 bool reinjecting; 586 587 /* reset sequence handling */ 588 bool reset_canceled; 589 unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)]; 590 int reset_seq_len; 591 int reset_seq_cnt; 592 int reset_seq_version; 593 struct timer_list keyreset_timer; 594 }; 595 596 #define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */ 597 static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX]; 598 static unsigned int sysrq_reset_seq_len; 599 static unsigned int sysrq_reset_seq_version = 1; 600 601 static void sysrq_parse_reset_sequence(struct sysrq_state *state) 602 { 603 int i; 604 unsigned short key; 605 606 state->reset_seq_cnt = 0; 607 608 for (i = 0; i < sysrq_reset_seq_len; i++) { 609 key = sysrq_reset_seq[i]; 610 611 if (key == KEY_RESERVED || key > KEY_MAX) 612 break; 613 614 __set_bit(key, state->reset_keybit); 615 state->reset_seq_len++; 616 617 if (test_bit(key, state->key_down)) 618 state->reset_seq_cnt++; 619 } 620 621 /* Disable reset until old keys are not released */ 622 state->reset_canceled = state->reset_seq_cnt != 0; 623 624 state->reset_seq_version = sysrq_reset_seq_version; 625 } 626 627 static void sysrq_do_reset(unsigned long dummy) 628 { 629 __handle_sysrq(sysrq_xlate[KEY_B], false); 630 } 631 632 static void sysrq_handle_reset_request(struct sysrq_state *state) 633 { 634 if (sysrq_reset_downtime_ms) 635 mod_timer(&state->keyreset_timer, 636 jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms)); 637 else 638 sysrq_do_reset(0); 639 } 640 641 static void sysrq_detect_reset_sequence(struct sysrq_state *state, 642 unsigned int code, int value) 643 { 644 if (!test_bit(code, state->reset_keybit)) { 645 /* 646 * Pressing any key _not_ in reset sequence cancels 647 * the reset sequence. Also cancelling the timer in 648 * case additional keys were pressed after a reset 649 * has been requested. 650 */ 651 if (value && state->reset_seq_cnt) { 652 state->reset_canceled = true; 653 del_timer(&state->keyreset_timer); 654 } 655 } else if (value == 0) { 656 /* 657 * Key release - all keys in the reset sequence need 658 * to be pressed and held for the reset timeout 659 * to hold. 660 */ 661 del_timer(&state->keyreset_timer); 662 663 if (--state->reset_seq_cnt == 0) 664 state->reset_canceled = false; 665 } else if (value == 1) { 666 /* key press, not autorepeat */ 667 if (++state->reset_seq_cnt == state->reset_seq_len && 668 !state->reset_canceled) { 669 sysrq_handle_reset_request(state); 670 } 671 } 672 } 673 674 static void sysrq_reinject_alt_sysrq(struct work_struct *work) 675 { 676 struct sysrq_state *sysrq = 677 container_of(work, struct sysrq_state, reinject_work); 678 struct input_handle *handle = &sysrq->handle; 679 unsigned int alt_code = sysrq->alt_use; 680 681 if (sysrq->need_reinject) { 682 /* we do not want the assignment to be reordered */ 683 sysrq->reinjecting = true; 684 mb(); 685 686 /* Simulate press and release of Alt + SysRq */ 687 input_inject_event(handle, EV_KEY, alt_code, 1); 688 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1); 689 input_inject_event(handle, EV_SYN, SYN_REPORT, 1); 690 691 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0); 692 input_inject_event(handle, EV_KEY, alt_code, 0); 693 input_inject_event(handle, EV_SYN, SYN_REPORT, 1); 694 695 mb(); 696 sysrq->reinjecting = false; 697 } 698 } 699 700 static bool sysrq_handle_keypress(struct sysrq_state *sysrq, 701 unsigned int code, int value) 702 { 703 bool was_active = sysrq->active; 704 bool suppress; 705 706 switch (code) { 707 708 case KEY_LEFTALT: 709 case KEY_RIGHTALT: 710 if (!value) { 711 /* One of ALTs is being released */ 712 if (sysrq->active && code == sysrq->alt_use) 713 sysrq->active = false; 714 715 sysrq->alt = KEY_RESERVED; 716 717 } else if (value != 2) { 718 sysrq->alt = code; 719 sysrq->need_reinject = false; 720 } 721 break; 722 723 case KEY_SYSRQ: 724 if (value == 1 && sysrq->alt != KEY_RESERVED) { 725 sysrq->active = true; 726 sysrq->alt_use = sysrq->alt; 727 /* 728 * If nothing else will be pressed we'll need 729 * to re-inject Alt-SysRq keysroke. 730 */ 731 sysrq->need_reinject = true; 732 } 733 734 /* 735 * Pretend that sysrq was never pressed at all. This 736 * is needed to properly handle KGDB which will try 737 * to release all keys after exiting debugger. If we 738 * do not clear key bit it KGDB will end up sending 739 * release events for Alt and SysRq, potentially 740 * triggering print screen function. 741 */ 742 if (sysrq->active) 743 clear_bit(KEY_SYSRQ, sysrq->handle.dev->key); 744 745 break; 746 747 default: 748 if (sysrq->active && value && value != 2) { 749 sysrq->need_reinject = false; 750 __handle_sysrq(sysrq_xlate[code], true); 751 } 752 break; 753 } 754 755 suppress = sysrq->active; 756 757 if (!sysrq->active) { 758 759 /* 760 * See if reset sequence has changed since the last time. 761 */ 762 if (sysrq->reset_seq_version != sysrq_reset_seq_version) 763 sysrq_parse_reset_sequence(sysrq); 764 765 /* 766 * If we are not suppressing key presses keep track of 767 * keyboard state so we can release keys that have been 768 * pressed before entering SysRq mode. 769 */ 770 if (value) 771 set_bit(code, sysrq->key_down); 772 else 773 clear_bit(code, sysrq->key_down); 774 775 if (was_active) 776 schedule_work(&sysrq->reinject_work); 777 778 /* Check for reset sequence */ 779 sysrq_detect_reset_sequence(sysrq, code, value); 780 781 } else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) { 782 /* 783 * Pass on release events for keys that was pressed before 784 * entering SysRq mode. 785 */ 786 suppress = false; 787 } 788 789 return suppress; 790 } 791 792 static bool sysrq_filter(struct input_handle *handle, 793 unsigned int type, unsigned int code, int value) 794 { 795 struct sysrq_state *sysrq = handle->private; 796 bool suppress; 797 798 /* 799 * Do not filter anything if we are in the process of re-injecting 800 * Alt+SysRq combination. 801 */ 802 if (sysrq->reinjecting) 803 return false; 804 805 switch (type) { 806 807 case EV_SYN: 808 suppress = false; 809 break; 810 811 case EV_KEY: 812 suppress = sysrq_handle_keypress(sysrq, code, value); 813 break; 814 815 default: 816 suppress = sysrq->active; 817 break; 818 } 819 820 return suppress; 821 } 822 823 static int sysrq_connect(struct input_handler *handler, 824 struct input_dev *dev, 825 const struct input_device_id *id) 826 { 827 struct sysrq_state *sysrq; 828 int error; 829 830 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL); 831 if (!sysrq) 832 return -ENOMEM; 833 834 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq); 835 836 sysrq->handle.dev = dev; 837 sysrq->handle.handler = handler; 838 sysrq->handle.name = "sysrq"; 839 sysrq->handle.private = sysrq; 840 setup_timer(&sysrq->keyreset_timer, sysrq_do_reset, 0); 841 842 error = input_register_handle(&sysrq->handle); 843 if (error) { 844 pr_err("Failed to register input sysrq handler, error %d\n", 845 error); 846 goto err_free; 847 } 848 849 error = input_open_device(&sysrq->handle); 850 if (error) { 851 pr_err("Failed to open input device, error %d\n", error); 852 goto err_unregister; 853 } 854 855 return 0; 856 857 err_unregister: 858 input_unregister_handle(&sysrq->handle); 859 err_free: 860 kfree(sysrq); 861 return error; 862 } 863 864 static void sysrq_disconnect(struct input_handle *handle) 865 { 866 struct sysrq_state *sysrq = handle->private; 867 868 input_close_device(handle); 869 cancel_work_sync(&sysrq->reinject_work); 870 del_timer_sync(&sysrq->keyreset_timer); 871 input_unregister_handle(handle); 872 kfree(sysrq); 873 } 874 875 /* 876 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all 877 * keyboards have SysRq key predefined and so user may add it to keymap 878 * later, but we expect all such keyboards to have left alt. 879 */ 880 static const struct input_device_id sysrq_ids[] = { 881 { 882 .flags = INPUT_DEVICE_ID_MATCH_EVBIT | 883 INPUT_DEVICE_ID_MATCH_KEYBIT, 884 .evbit = { BIT_MASK(EV_KEY) }, 885 .keybit = { BIT_MASK(KEY_LEFTALT) }, 886 }, 887 { }, 888 }; 889 890 static struct input_handler sysrq_handler = { 891 .filter = sysrq_filter, 892 .connect = sysrq_connect, 893 .disconnect = sysrq_disconnect, 894 .name = "sysrq", 895 .id_table = sysrq_ids, 896 }; 897 898 static bool sysrq_handler_registered; 899 900 static inline void sysrq_register_handler(void) 901 { 902 unsigned short key; 903 int error; 904 int i; 905 906 for (i = 0; i < ARRAY_SIZE(sysrq_reset_seq); i++) { 907 key = platform_sysrq_reset_seq[i]; 908 if (key == KEY_RESERVED || key > KEY_MAX) 909 break; 910 911 sysrq_reset_seq[sysrq_reset_seq_len++] = key; 912 } 913 914 error = input_register_handler(&sysrq_handler); 915 if (error) 916 pr_err("Failed to register input handler, error %d", error); 917 else 918 sysrq_handler_registered = true; 919 } 920 921 static inline void sysrq_unregister_handler(void) 922 { 923 if (sysrq_handler_registered) { 924 input_unregister_handler(&sysrq_handler); 925 sysrq_handler_registered = false; 926 } 927 } 928 929 static int sysrq_reset_seq_param_set(const char *buffer, 930 const struct kernel_param *kp) 931 { 932 unsigned long val; 933 int error; 934 935 error = strict_strtoul(buffer, 0, &val); 936 if (error < 0) 937 return error; 938 939 if (val > KEY_MAX) 940 return -EINVAL; 941 942 *((unsigned short *)kp->arg) = val; 943 sysrq_reset_seq_version++; 944 945 return 0; 946 } 947 948 static struct kernel_param_ops param_ops_sysrq_reset_seq = { 949 .get = param_get_ushort, 950 .set = sysrq_reset_seq_param_set, 951 }; 952 953 #define param_check_sysrq_reset_seq(name, p) \ 954 __param_check(name, p, unsigned short) 955 956 module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq, 957 &sysrq_reset_seq_len, 0644); 958 959 module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644); 960 961 #else 962 963 static inline void sysrq_register_handler(void) 964 { 965 } 966 967 static inline void sysrq_unregister_handler(void) 968 { 969 } 970 971 #endif /* CONFIG_INPUT */ 972 973 int sysrq_toggle_support(int enable_mask) 974 { 975 bool was_enabled = sysrq_on(); 976 977 sysrq_enabled = enable_mask; 978 979 if (was_enabled != sysrq_on()) { 980 if (sysrq_on()) 981 sysrq_register_handler(); 982 else 983 sysrq_unregister_handler(); 984 } 985 986 return 0; 987 } 988 989 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p, 990 struct sysrq_key_op *remove_op_p) 991 { 992 int retval; 993 unsigned long flags; 994 995 spin_lock_irqsave(&sysrq_key_table_lock, flags); 996 if (__sysrq_get_key_op(key) == remove_op_p) { 997 __sysrq_put_key_op(key, insert_op_p); 998 retval = 0; 999 } else { 1000 retval = -1; 1001 } 1002 spin_unlock_irqrestore(&sysrq_key_table_lock, flags); 1003 return retval; 1004 } 1005 1006 int register_sysrq_key(int key, struct sysrq_key_op *op_p) 1007 { 1008 return __sysrq_swap_key_ops(key, op_p, NULL); 1009 } 1010 EXPORT_SYMBOL(register_sysrq_key); 1011 1012 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p) 1013 { 1014 return __sysrq_swap_key_ops(key, NULL, op_p); 1015 } 1016 EXPORT_SYMBOL(unregister_sysrq_key); 1017 1018 #ifdef CONFIG_PROC_FS 1019 /* 1020 * writing 'C' to /proc/sysrq-trigger is like sysrq-C 1021 */ 1022 static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf, 1023 size_t count, loff_t *ppos) 1024 { 1025 if (count) { 1026 char c; 1027 1028 if (get_user(c, buf)) 1029 return -EFAULT; 1030 __handle_sysrq(c, false); 1031 } 1032 1033 return count; 1034 } 1035 1036 static const struct file_operations proc_sysrq_trigger_operations = { 1037 .write = write_sysrq_trigger, 1038 .llseek = noop_llseek, 1039 }; 1040 1041 static void sysrq_init_procfs(void) 1042 { 1043 if (!proc_create("sysrq-trigger", S_IWUSR, NULL, 1044 &proc_sysrq_trigger_operations)) 1045 pr_err("Failed to register proc interface\n"); 1046 } 1047 1048 #else 1049 1050 static inline void sysrq_init_procfs(void) 1051 { 1052 } 1053 1054 #endif /* CONFIG_PROC_FS */ 1055 1056 static int __init sysrq_init(void) 1057 { 1058 sysrq_init_procfs(); 1059 1060 if (sysrq_on()) 1061 sysrq_register_handler(); 1062 1063 return 0; 1064 } 1065 module_init(sysrq_init); 1066