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 #include <linux/syscalls.h> 48 #include <linux/of.h> 49 #include <linux/rcupdate.h> 50 51 #include <asm/ptrace.h> 52 #include <asm/irq_regs.h> 53 54 /* Whether we react on sysrq keys or just ignore them */ 55 static int __read_mostly sysrq_enabled = CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE; 56 static bool __read_mostly sysrq_always_enabled; 57 58 unsigned short platform_sysrq_reset_seq[] __weak = { KEY_RESERVED }; 59 int sysrq_reset_downtime_ms __weak; 60 61 static bool sysrq_on(void) 62 { 63 return sysrq_enabled || sysrq_always_enabled; 64 } 65 66 /* 67 * A value of 1 means 'all', other nonzero values are an op mask: 68 */ 69 static bool sysrq_on_mask(int mask) 70 { 71 return sysrq_always_enabled || 72 sysrq_enabled == 1 || 73 (sysrq_enabled & mask); 74 } 75 76 static int __init sysrq_always_enabled_setup(char *str) 77 { 78 sysrq_always_enabled = true; 79 pr_info("sysrq always enabled.\n"); 80 81 return 1; 82 } 83 84 __setup("sysrq_always_enabled", sysrq_always_enabled_setup); 85 86 87 static void sysrq_handle_loglevel(int key) 88 { 89 int i; 90 91 i = key - '0'; 92 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT; 93 pr_info("Loglevel set to %d\n", i); 94 console_loglevel = i; 95 } 96 static struct sysrq_key_op sysrq_loglevel_op = { 97 .handler = sysrq_handle_loglevel, 98 .help_msg = "loglevel(0-9)", 99 .action_msg = "Changing Loglevel", 100 .enable_mask = SYSRQ_ENABLE_LOG, 101 }; 102 103 #ifdef CONFIG_VT 104 static void sysrq_handle_SAK(int key) 105 { 106 struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work; 107 schedule_work(SAK_work); 108 } 109 static struct sysrq_key_op sysrq_SAK_op = { 110 .handler = sysrq_handle_SAK, 111 .help_msg = "sak(k)", 112 .action_msg = "SAK", 113 .enable_mask = SYSRQ_ENABLE_KEYBOARD, 114 }; 115 #else 116 #define sysrq_SAK_op (*(struct sysrq_key_op *)NULL) 117 #endif 118 119 #ifdef CONFIG_VT 120 static void sysrq_handle_unraw(int key) 121 { 122 vt_reset_unicode(fg_console); 123 } 124 125 static struct sysrq_key_op sysrq_unraw_op = { 126 .handler = sysrq_handle_unraw, 127 .help_msg = "unraw(r)", 128 .action_msg = "Keyboard mode set to system default", 129 .enable_mask = SYSRQ_ENABLE_KEYBOARD, 130 }; 131 #else 132 #define sysrq_unraw_op (*(struct sysrq_key_op *)NULL) 133 #endif /* CONFIG_VT */ 134 135 static void sysrq_handle_crash(int key) 136 { 137 char *killer = NULL; 138 139 panic_on_oops = 1; /* force panic */ 140 wmb(); 141 *killer = 1; 142 } 143 static struct sysrq_key_op sysrq_crash_op = { 144 .handler = sysrq_handle_crash, 145 .help_msg = "crash(c)", 146 .action_msg = "Trigger a crash", 147 .enable_mask = SYSRQ_ENABLE_DUMP, 148 }; 149 150 static void sysrq_handle_reboot(int key) 151 { 152 lockdep_off(); 153 local_irq_enable(); 154 emergency_restart(); 155 } 156 static struct sysrq_key_op sysrq_reboot_op = { 157 .handler = sysrq_handle_reboot, 158 .help_msg = "reboot(b)", 159 .action_msg = "Resetting", 160 .enable_mask = SYSRQ_ENABLE_BOOT, 161 }; 162 163 static void sysrq_handle_sync(int key) 164 { 165 emergency_sync(); 166 } 167 static struct sysrq_key_op sysrq_sync_op = { 168 .handler = sysrq_handle_sync, 169 .help_msg = "sync(s)", 170 .action_msg = "Emergency Sync", 171 .enable_mask = SYSRQ_ENABLE_SYNC, 172 }; 173 174 static void sysrq_handle_show_timers(int key) 175 { 176 sysrq_timer_list_show(); 177 } 178 179 static struct sysrq_key_op sysrq_show_timers_op = { 180 .handler = sysrq_handle_show_timers, 181 .help_msg = "show-all-timers(q)", 182 .action_msg = "Show clockevent devices & pending hrtimers (no others)", 183 }; 184 185 static void sysrq_handle_mountro(int key) 186 { 187 emergency_remount(); 188 } 189 static struct sysrq_key_op sysrq_mountro_op = { 190 .handler = sysrq_handle_mountro, 191 .help_msg = "unmount(u)", 192 .action_msg = "Emergency Remount R/O", 193 .enable_mask = SYSRQ_ENABLE_REMOUNT, 194 }; 195 196 #ifdef CONFIG_LOCKDEP 197 static void sysrq_handle_showlocks(int key) 198 { 199 debug_show_all_locks(); 200 } 201 202 static struct sysrq_key_op sysrq_showlocks_op = { 203 .handler = sysrq_handle_showlocks, 204 .help_msg = "show-all-locks(d)", 205 .action_msg = "Show Locks Held", 206 }; 207 #else 208 #define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL) 209 #endif 210 211 #ifdef CONFIG_SMP 212 static DEFINE_SPINLOCK(show_lock); 213 214 static void showacpu(void *dummy) 215 { 216 unsigned long flags; 217 218 /* Idle CPUs have no interesting backtrace. */ 219 if (idle_cpu(smp_processor_id())) 220 return; 221 222 spin_lock_irqsave(&show_lock, flags); 223 pr_info("CPU%d:\n", smp_processor_id()); 224 show_stack(NULL, NULL); 225 spin_unlock_irqrestore(&show_lock, flags); 226 } 227 228 static void sysrq_showregs_othercpus(struct work_struct *dummy) 229 { 230 smp_call_function(showacpu, NULL, 0); 231 } 232 233 static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus); 234 235 static void sysrq_handle_showallcpus(int key) 236 { 237 /* 238 * Fall back to the workqueue based printing if the 239 * backtrace printing did not succeed or the 240 * architecture has no support for it: 241 */ 242 if (!trigger_all_cpu_backtrace()) { 243 struct pt_regs *regs = get_irq_regs(); 244 245 if (regs) { 246 pr_info("CPU%d:\n", smp_processor_id()); 247 show_regs(regs); 248 } 249 schedule_work(&sysrq_showallcpus); 250 } 251 } 252 253 static struct sysrq_key_op sysrq_showallcpus_op = { 254 .handler = sysrq_handle_showallcpus, 255 .help_msg = "show-backtrace-all-active-cpus(l)", 256 .action_msg = "Show backtrace of all active CPUs", 257 .enable_mask = SYSRQ_ENABLE_DUMP, 258 }; 259 #endif 260 261 static void sysrq_handle_showregs(int key) 262 { 263 struct pt_regs *regs = get_irq_regs(); 264 if (regs) 265 show_regs(regs); 266 perf_event_print_debug(); 267 } 268 static struct sysrq_key_op sysrq_showregs_op = { 269 .handler = sysrq_handle_showregs, 270 .help_msg = "show-registers(p)", 271 .action_msg = "Show Regs", 272 .enable_mask = SYSRQ_ENABLE_DUMP, 273 }; 274 275 static void sysrq_handle_showstate(int key) 276 { 277 show_state(); 278 show_workqueue_state(); 279 } 280 static struct sysrq_key_op sysrq_showstate_op = { 281 .handler = sysrq_handle_showstate, 282 .help_msg = "show-task-states(t)", 283 .action_msg = "Show State", 284 .enable_mask = SYSRQ_ENABLE_DUMP, 285 }; 286 287 static void sysrq_handle_showstate_blocked(int key) 288 { 289 show_state_filter(TASK_UNINTERRUPTIBLE); 290 } 291 static struct sysrq_key_op sysrq_showstate_blocked_op = { 292 .handler = sysrq_handle_showstate_blocked, 293 .help_msg = "show-blocked-tasks(w)", 294 .action_msg = "Show Blocked State", 295 .enable_mask = SYSRQ_ENABLE_DUMP, 296 }; 297 298 #ifdef CONFIG_TRACING 299 #include <linux/ftrace.h> 300 301 static void sysrq_ftrace_dump(int key) 302 { 303 ftrace_dump(DUMP_ALL); 304 } 305 static struct sysrq_key_op sysrq_ftrace_dump_op = { 306 .handler = sysrq_ftrace_dump, 307 .help_msg = "dump-ftrace-buffer(z)", 308 .action_msg = "Dump ftrace buffer", 309 .enable_mask = SYSRQ_ENABLE_DUMP, 310 }; 311 #else 312 #define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL) 313 #endif 314 315 static void sysrq_handle_showmem(int key) 316 { 317 show_mem(0); 318 } 319 static struct sysrq_key_op sysrq_showmem_op = { 320 .handler = sysrq_handle_showmem, 321 .help_msg = "show-memory-usage(m)", 322 .action_msg = "Show Memory", 323 .enable_mask = SYSRQ_ENABLE_DUMP, 324 }; 325 326 /* 327 * Signal sysrq helper function. Sends a signal to all user processes. 328 */ 329 static void send_sig_all(int sig) 330 { 331 struct task_struct *p; 332 333 read_lock(&tasklist_lock); 334 for_each_process(p) { 335 if (p->flags & PF_KTHREAD) 336 continue; 337 if (is_global_init(p)) 338 continue; 339 340 do_send_sig_info(sig, SEND_SIG_FORCED, p, true); 341 } 342 read_unlock(&tasklist_lock); 343 } 344 345 static void sysrq_handle_term(int key) 346 { 347 send_sig_all(SIGTERM); 348 console_loglevel = CONSOLE_LOGLEVEL_DEBUG; 349 } 350 static struct sysrq_key_op sysrq_term_op = { 351 .handler = sysrq_handle_term, 352 .help_msg = "terminate-all-tasks(e)", 353 .action_msg = "Terminate All Tasks", 354 .enable_mask = SYSRQ_ENABLE_SIGNAL, 355 }; 356 357 static void moom_callback(struct work_struct *ignored) 358 { 359 if (!out_of_memory(node_zonelist(first_memory_node, GFP_KERNEL), 360 GFP_KERNEL, 0, NULL, true)) 361 pr_info("OOM request ignored because killer is disabled\n"); 362 } 363 364 static DECLARE_WORK(moom_work, moom_callback); 365 366 static void sysrq_handle_moom(int key) 367 { 368 schedule_work(&moom_work); 369 } 370 static struct sysrq_key_op sysrq_moom_op = { 371 .handler = sysrq_handle_moom, 372 .help_msg = "memory-full-oom-kill(f)", 373 .action_msg = "Manual OOM execution", 374 .enable_mask = SYSRQ_ENABLE_SIGNAL, 375 }; 376 377 #ifdef CONFIG_BLOCK 378 static void sysrq_handle_thaw(int key) 379 { 380 emergency_thaw_all(); 381 } 382 static struct sysrq_key_op sysrq_thaw_op = { 383 .handler = sysrq_handle_thaw, 384 .help_msg = "thaw-filesystems(j)", 385 .action_msg = "Emergency Thaw of all frozen filesystems", 386 .enable_mask = SYSRQ_ENABLE_SIGNAL, 387 }; 388 #endif 389 390 static void sysrq_handle_kill(int key) 391 { 392 send_sig_all(SIGKILL); 393 console_loglevel = CONSOLE_LOGLEVEL_DEBUG; 394 } 395 static struct sysrq_key_op sysrq_kill_op = { 396 .handler = sysrq_handle_kill, 397 .help_msg = "kill-all-tasks(i)", 398 .action_msg = "Kill All Tasks", 399 .enable_mask = SYSRQ_ENABLE_SIGNAL, 400 }; 401 402 static void sysrq_handle_unrt(int key) 403 { 404 normalize_rt_tasks(); 405 } 406 static struct sysrq_key_op sysrq_unrt_op = { 407 .handler = sysrq_handle_unrt, 408 .help_msg = "nice-all-RT-tasks(n)", 409 .action_msg = "Nice All RT Tasks", 410 .enable_mask = SYSRQ_ENABLE_RTNICE, 411 }; 412 413 /* Key Operations table and lock */ 414 static DEFINE_SPINLOCK(sysrq_key_table_lock); 415 416 static struct sysrq_key_op *sysrq_key_table[36] = { 417 &sysrq_loglevel_op, /* 0 */ 418 &sysrq_loglevel_op, /* 1 */ 419 &sysrq_loglevel_op, /* 2 */ 420 &sysrq_loglevel_op, /* 3 */ 421 &sysrq_loglevel_op, /* 4 */ 422 &sysrq_loglevel_op, /* 5 */ 423 &sysrq_loglevel_op, /* 6 */ 424 &sysrq_loglevel_op, /* 7 */ 425 &sysrq_loglevel_op, /* 8 */ 426 &sysrq_loglevel_op, /* 9 */ 427 428 /* 429 * a: Don't use for system provided sysrqs, it is handled specially on 430 * sparc and will never arrive. 431 */ 432 NULL, /* a */ 433 &sysrq_reboot_op, /* b */ 434 &sysrq_crash_op, /* c & ibm_emac driver debug */ 435 &sysrq_showlocks_op, /* d */ 436 &sysrq_term_op, /* e */ 437 &sysrq_moom_op, /* f */ 438 /* g: May be registered for the kernel debugger */ 439 NULL, /* g */ 440 NULL, /* h - reserved for help */ 441 &sysrq_kill_op, /* i */ 442 #ifdef CONFIG_BLOCK 443 &sysrq_thaw_op, /* j */ 444 #else 445 NULL, /* j */ 446 #endif 447 &sysrq_SAK_op, /* k */ 448 #ifdef CONFIG_SMP 449 &sysrq_showallcpus_op, /* l */ 450 #else 451 NULL, /* l */ 452 #endif 453 &sysrq_showmem_op, /* m */ 454 &sysrq_unrt_op, /* n */ 455 /* o: This will often be registered as 'Off' at init time */ 456 NULL, /* o */ 457 &sysrq_showregs_op, /* p */ 458 &sysrq_show_timers_op, /* q */ 459 &sysrq_unraw_op, /* r */ 460 &sysrq_sync_op, /* s */ 461 &sysrq_showstate_op, /* t */ 462 &sysrq_mountro_op, /* u */ 463 /* v: May be registered for frame buffer console restore */ 464 NULL, /* v */ 465 &sysrq_showstate_blocked_op, /* w */ 466 /* x: May be registered on ppc/powerpc for xmon */ 467 /* x: May be registered on sparc64 for global PMU dump */ 468 NULL, /* x */ 469 /* y: May be registered on sparc64 for global register dump */ 470 NULL, /* y */ 471 &sysrq_ftrace_dump_op, /* z */ 472 }; 473 474 /* key2index calculation, -1 on invalid index */ 475 static int sysrq_key_table_key2index(int key) 476 { 477 int retval; 478 479 if ((key >= '0') && (key <= '9')) 480 retval = key - '0'; 481 else if ((key >= 'a') && (key <= 'z')) 482 retval = key + 10 - 'a'; 483 else 484 retval = -1; 485 return retval; 486 } 487 488 /* 489 * get and put functions for the table, exposed to modules. 490 */ 491 struct sysrq_key_op *__sysrq_get_key_op(int key) 492 { 493 struct sysrq_key_op *op_p = NULL; 494 int i; 495 496 i = sysrq_key_table_key2index(key); 497 if (i != -1) 498 op_p = sysrq_key_table[i]; 499 500 return op_p; 501 } 502 503 static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p) 504 { 505 int i = sysrq_key_table_key2index(key); 506 507 if (i != -1) 508 sysrq_key_table[i] = op_p; 509 } 510 511 void __handle_sysrq(int key, bool check_mask) 512 { 513 struct sysrq_key_op *op_p; 514 int orig_log_level; 515 int i; 516 517 rcu_sysrq_start(); 518 rcu_read_lock(); 519 /* 520 * Raise the apparent loglevel to maximum so that the sysrq header 521 * is shown to provide the user with positive feedback. We do not 522 * simply emit this at KERN_EMERG as that would change message 523 * routing in the consumers of /proc/kmsg. 524 */ 525 orig_log_level = console_loglevel; 526 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT; 527 pr_info("SysRq : "); 528 529 op_p = __sysrq_get_key_op(key); 530 if (op_p) { 531 /* 532 * Should we check for enabled operations (/proc/sysrq-trigger 533 * should not) and is the invoked operation enabled? 534 */ 535 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) { 536 pr_cont("%s\n", op_p->action_msg); 537 console_loglevel = orig_log_level; 538 op_p->handler(key); 539 } else { 540 pr_cont("This sysrq operation is disabled.\n"); 541 } 542 } else { 543 pr_cont("HELP : "); 544 /* Only print the help msg once per handler */ 545 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) { 546 if (sysrq_key_table[i]) { 547 int j; 548 549 for (j = 0; sysrq_key_table[i] != 550 sysrq_key_table[j]; j++) 551 ; 552 if (j != i) 553 continue; 554 pr_cont("%s ", sysrq_key_table[i]->help_msg); 555 } 556 } 557 pr_cont("\n"); 558 console_loglevel = orig_log_level; 559 } 560 rcu_read_unlock(); 561 rcu_sysrq_end(); 562 } 563 564 void handle_sysrq(int key) 565 { 566 if (sysrq_on()) 567 __handle_sysrq(key, true); 568 } 569 EXPORT_SYMBOL(handle_sysrq); 570 571 #ifdef CONFIG_INPUT 572 573 /* Simple translation table for the SysRq keys */ 574 static const unsigned char sysrq_xlate[KEY_CNT] = 575 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */ 576 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */ 577 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */ 578 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */ 579 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */ 580 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */ 581 "\r\000/"; /* 0x60 - 0x6f */ 582 583 struct sysrq_state { 584 struct input_handle handle; 585 struct work_struct reinject_work; 586 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)]; 587 unsigned int alt; 588 unsigned int alt_use; 589 bool active; 590 bool need_reinject; 591 bool reinjecting; 592 593 /* reset sequence handling */ 594 bool reset_canceled; 595 bool reset_requested; 596 unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)]; 597 int reset_seq_len; 598 int reset_seq_cnt; 599 int reset_seq_version; 600 struct timer_list keyreset_timer; 601 }; 602 603 #define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */ 604 static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX]; 605 static unsigned int sysrq_reset_seq_len; 606 static unsigned int sysrq_reset_seq_version = 1; 607 608 static void sysrq_parse_reset_sequence(struct sysrq_state *state) 609 { 610 int i; 611 unsigned short key; 612 613 state->reset_seq_cnt = 0; 614 615 for (i = 0; i < sysrq_reset_seq_len; i++) { 616 key = sysrq_reset_seq[i]; 617 618 if (key == KEY_RESERVED || key > KEY_MAX) 619 break; 620 621 __set_bit(key, state->reset_keybit); 622 state->reset_seq_len++; 623 624 if (test_bit(key, state->key_down)) 625 state->reset_seq_cnt++; 626 } 627 628 /* Disable reset until old keys are not released */ 629 state->reset_canceled = state->reset_seq_cnt != 0; 630 631 state->reset_seq_version = sysrq_reset_seq_version; 632 } 633 634 static void sysrq_do_reset(unsigned long _state) 635 { 636 struct sysrq_state *state = (struct sysrq_state *) _state; 637 638 state->reset_requested = true; 639 640 sys_sync(); 641 kernel_restart(NULL); 642 } 643 644 static void sysrq_handle_reset_request(struct sysrq_state *state) 645 { 646 if (state->reset_requested) 647 __handle_sysrq(sysrq_xlate[KEY_B], false); 648 649 if (sysrq_reset_downtime_ms) 650 mod_timer(&state->keyreset_timer, 651 jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms)); 652 else 653 sysrq_do_reset((unsigned long)state); 654 } 655 656 static void sysrq_detect_reset_sequence(struct sysrq_state *state, 657 unsigned int code, int value) 658 { 659 if (!test_bit(code, state->reset_keybit)) { 660 /* 661 * Pressing any key _not_ in reset sequence cancels 662 * the reset sequence. Also cancelling the timer in 663 * case additional keys were pressed after a reset 664 * has been requested. 665 */ 666 if (value && state->reset_seq_cnt) { 667 state->reset_canceled = true; 668 del_timer(&state->keyreset_timer); 669 } 670 } else if (value == 0) { 671 /* 672 * Key release - all keys in the reset sequence need 673 * to be pressed and held for the reset timeout 674 * to hold. 675 */ 676 del_timer(&state->keyreset_timer); 677 678 if (--state->reset_seq_cnt == 0) 679 state->reset_canceled = false; 680 } else if (value == 1) { 681 /* key press, not autorepeat */ 682 if (++state->reset_seq_cnt == state->reset_seq_len && 683 !state->reset_canceled) { 684 sysrq_handle_reset_request(state); 685 } 686 } 687 } 688 689 #ifdef CONFIG_OF 690 static void sysrq_of_get_keyreset_config(void) 691 { 692 u32 key; 693 struct device_node *np; 694 struct property *prop; 695 const __be32 *p; 696 697 np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq"); 698 if (!np) { 699 pr_debug("No sysrq node found"); 700 return; 701 } 702 703 /* Reset in case a __weak definition was present */ 704 sysrq_reset_seq_len = 0; 705 706 of_property_for_each_u32(np, "keyset", prop, p, key) { 707 if (key == KEY_RESERVED || key > KEY_MAX || 708 sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX) 709 break; 710 711 sysrq_reset_seq[sysrq_reset_seq_len++] = (unsigned short)key; 712 } 713 714 /* Get reset timeout if any. */ 715 of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms); 716 } 717 #else 718 static void sysrq_of_get_keyreset_config(void) 719 { 720 } 721 #endif 722 723 static void sysrq_reinject_alt_sysrq(struct work_struct *work) 724 { 725 struct sysrq_state *sysrq = 726 container_of(work, struct sysrq_state, reinject_work); 727 struct input_handle *handle = &sysrq->handle; 728 unsigned int alt_code = sysrq->alt_use; 729 730 if (sysrq->need_reinject) { 731 /* we do not want the assignment to be reordered */ 732 sysrq->reinjecting = true; 733 mb(); 734 735 /* Simulate press and release of Alt + SysRq */ 736 input_inject_event(handle, EV_KEY, alt_code, 1); 737 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1); 738 input_inject_event(handle, EV_SYN, SYN_REPORT, 1); 739 740 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0); 741 input_inject_event(handle, EV_KEY, alt_code, 0); 742 input_inject_event(handle, EV_SYN, SYN_REPORT, 1); 743 744 mb(); 745 sysrq->reinjecting = false; 746 } 747 } 748 749 static bool sysrq_handle_keypress(struct sysrq_state *sysrq, 750 unsigned int code, int value) 751 { 752 bool was_active = sysrq->active; 753 bool suppress; 754 755 switch (code) { 756 757 case KEY_LEFTALT: 758 case KEY_RIGHTALT: 759 if (!value) { 760 /* One of ALTs is being released */ 761 if (sysrq->active && code == sysrq->alt_use) 762 sysrq->active = false; 763 764 sysrq->alt = KEY_RESERVED; 765 766 } else if (value != 2) { 767 sysrq->alt = code; 768 sysrq->need_reinject = false; 769 } 770 break; 771 772 case KEY_SYSRQ: 773 if (value == 1 && sysrq->alt != KEY_RESERVED) { 774 sysrq->active = true; 775 sysrq->alt_use = sysrq->alt; 776 /* 777 * If nothing else will be pressed we'll need 778 * to re-inject Alt-SysRq keysroke. 779 */ 780 sysrq->need_reinject = true; 781 } 782 783 /* 784 * Pretend that sysrq was never pressed at all. This 785 * is needed to properly handle KGDB which will try 786 * to release all keys after exiting debugger. If we 787 * do not clear key bit it KGDB will end up sending 788 * release events for Alt and SysRq, potentially 789 * triggering print screen function. 790 */ 791 if (sysrq->active) 792 clear_bit(KEY_SYSRQ, sysrq->handle.dev->key); 793 794 break; 795 796 default: 797 if (sysrq->active && value && value != 2) { 798 sysrq->need_reinject = false; 799 __handle_sysrq(sysrq_xlate[code], true); 800 } 801 break; 802 } 803 804 suppress = sysrq->active; 805 806 if (!sysrq->active) { 807 808 /* 809 * See if reset sequence has changed since the last time. 810 */ 811 if (sysrq->reset_seq_version != sysrq_reset_seq_version) 812 sysrq_parse_reset_sequence(sysrq); 813 814 /* 815 * If we are not suppressing key presses keep track of 816 * keyboard state so we can release keys that have been 817 * pressed before entering SysRq mode. 818 */ 819 if (value) 820 set_bit(code, sysrq->key_down); 821 else 822 clear_bit(code, sysrq->key_down); 823 824 if (was_active) 825 schedule_work(&sysrq->reinject_work); 826 827 /* Check for reset sequence */ 828 sysrq_detect_reset_sequence(sysrq, code, value); 829 830 } else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) { 831 /* 832 * Pass on release events for keys that was pressed before 833 * entering SysRq mode. 834 */ 835 suppress = false; 836 } 837 838 return suppress; 839 } 840 841 static bool sysrq_filter(struct input_handle *handle, 842 unsigned int type, unsigned int code, int value) 843 { 844 struct sysrq_state *sysrq = handle->private; 845 bool suppress; 846 847 /* 848 * Do not filter anything if we are in the process of re-injecting 849 * Alt+SysRq combination. 850 */ 851 if (sysrq->reinjecting) 852 return false; 853 854 switch (type) { 855 856 case EV_SYN: 857 suppress = false; 858 break; 859 860 case EV_KEY: 861 suppress = sysrq_handle_keypress(sysrq, code, value); 862 break; 863 864 default: 865 suppress = sysrq->active; 866 break; 867 } 868 869 return suppress; 870 } 871 872 static int sysrq_connect(struct input_handler *handler, 873 struct input_dev *dev, 874 const struct input_device_id *id) 875 { 876 struct sysrq_state *sysrq; 877 int error; 878 879 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL); 880 if (!sysrq) 881 return -ENOMEM; 882 883 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq); 884 885 sysrq->handle.dev = dev; 886 sysrq->handle.handler = handler; 887 sysrq->handle.name = "sysrq"; 888 sysrq->handle.private = sysrq; 889 setup_timer(&sysrq->keyreset_timer, 890 sysrq_do_reset, (unsigned long)sysrq); 891 892 error = input_register_handle(&sysrq->handle); 893 if (error) { 894 pr_err("Failed to register input sysrq handler, error %d\n", 895 error); 896 goto err_free; 897 } 898 899 error = input_open_device(&sysrq->handle); 900 if (error) { 901 pr_err("Failed to open input device, error %d\n", error); 902 goto err_unregister; 903 } 904 905 return 0; 906 907 err_unregister: 908 input_unregister_handle(&sysrq->handle); 909 err_free: 910 kfree(sysrq); 911 return error; 912 } 913 914 static void sysrq_disconnect(struct input_handle *handle) 915 { 916 struct sysrq_state *sysrq = handle->private; 917 918 input_close_device(handle); 919 cancel_work_sync(&sysrq->reinject_work); 920 del_timer_sync(&sysrq->keyreset_timer); 921 input_unregister_handle(handle); 922 kfree(sysrq); 923 } 924 925 /* 926 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all 927 * keyboards have SysRq key predefined and so user may add it to keymap 928 * later, but we expect all such keyboards to have left alt. 929 */ 930 static const struct input_device_id sysrq_ids[] = { 931 { 932 .flags = INPUT_DEVICE_ID_MATCH_EVBIT | 933 INPUT_DEVICE_ID_MATCH_KEYBIT, 934 .evbit = { BIT_MASK(EV_KEY) }, 935 .keybit = { BIT_MASK(KEY_LEFTALT) }, 936 }, 937 { }, 938 }; 939 940 static struct input_handler sysrq_handler = { 941 .filter = sysrq_filter, 942 .connect = sysrq_connect, 943 .disconnect = sysrq_disconnect, 944 .name = "sysrq", 945 .id_table = sysrq_ids, 946 }; 947 948 static bool sysrq_handler_registered; 949 950 static inline void sysrq_register_handler(void) 951 { 952 unsigned short key; 953 int error; 954 int i; 955 956 /* First check if a __weak interface was instantiated. */ 957 for (i = 0; i < ARRAY_SIZE(sysrq_reset_seq); i++) { 958 key = platform_sysrq_reset_seq[i]; 959 if (key == KEY_RESERVED || key > KEY_MAX) 960 break; 961 962 sysrq_reset_seq[sysrq_reset_seq_len++] = key; 963 } 964 965 /* 966 * DT configuration takes precedence over anything that would 967 * have been defined via the __weak interface. 968 */ 969 sysrq_of_get_keyreset_config(); 970 971 error = input_register_handler(&sysrq_handler); 972 if (error) 973 pr_err("Failed to register input handler, error %d", error); 974 else 975 sysrq_handler_registered = true; 976 } 977 978 static inline void sysrq_unregister_handler(void) 979 { 980 if (sysrq_handler_registered) { 981 input_unregister_handler(&sysrq_handler); 982 sysrq_handler_registered = false; 983 } 984 } 985 986 static int sysrq_reset_seq_param_set(const char *buffer, 987 const struct kernel_param *kp) 988 { 989 unsigned long val; 990 int error; 991 992 error = kstrtoul(buffer, 0, &val); 993 if (error < 0) 994 return error; 995 996 if (val > KEY_MAX) 997 return -EINVAL; 998 999 *((unsigned short *)kp->arg) = val; 1000 sysrq_reset_seq_version++; 1001 1002 return 0; 1003 } 1004 1005 static struct kernel_param_ops param_ops_sysrq_reset_seq = { 1006 .get = param_get_ushort, 1007 .set = sysrq_reset_seq_param_set, 1008 }; 1009 1010 #define param_check_sysrq_reset_seq(name, p) \ 1011 __param_check(name, p, unsigned short) 1012 1013 module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq, 1014 &sysrq_reset_seq_len, 0644); 1015 1016 module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644); 1017 1018 #else 1019 1020 static inline void sysrq_register_handler(void) 1021 { 1022 } 1023 1024 static inline void sysrq_unregister_handler(void) 1025 { 1026 } 1027 1028 #endif /* CONFIG_INPUT */ 1029 1030 int sysrq_toggle_support(int enable_mask) 1031 { 1032 bool was_enabled = sysrq_on(); 1033 1034 sysrq_enabled = enable_mask; 1035 1036 if (was_enabled != sysrq_on()) { 1037 if (sysrq_on()) 1038 sysrq_register_handler(); 1039 else 1040 sysrq_unregister_handler(); 1041 } 1042 1043 return 0; 1044 } 1045 1046 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p, 1047 struct sysrq_key_op *remove_op_p) 1048 { 1049 int retval; 1050 1051 spin_lock(&sysrq_key_table_lock); 1052 if (__sysrq_get_key_op(key) == remove_op_p) { 1053 __sysrq_put_key_op(key, insert_op_p); 1054 retval = 0; 1055 } else { 1056 retval = -1; 1057 } 1058 spin_unlock(&sysrq_key_table_lock); 1059 1060 /* 1061 * A concurrent __handle_sysrq either got the old op or the new op. 1062 * Wait for it to go away before returning, so the code for an old 1063 * op is not freed (eg. on module unload) while it is in use. 1064 */ 1065 synchronize_rcu(); 1066 1067 return retval; 1068 } 1069 1070 int register_sysrq_key(int key, struct sysrq_key_op *op_p) 1071 { 1072 return __sysrq_swap_key_ops(key, op_p, NULL); 1073 } 1074 EXPORT_SYMBOL(register_sysrq_key); 1075 1076 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p) 1077 { 1078 return __sysrq_swap_key_ops(key, NULL, op_p); 1079 } 1080 EXPORT_SYMBOL(unregister_sysrq_key); 1081 1082 #ifdef CONFIG_PROC_FS 1083 /* 1084 * writing 'C' to /proc/sysrq-trigger is like sysrq-C 1085 */ 1086 static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf, 1087 size_t count, loff_t *ppos) 1088 { 1089 if (count) { 1090 char c; 1091 1092 if (get_user(c, buf)) 1093 return -EFAULT; 1094 __handle_sysrq(c, false); 1095 } 1096 1097 return count; 1098 } 1099 1100 static const struct file_operations proc_sysrq_trigger_operations = { 1101 .write = write_sysrq_trigger, 1102 .llseek = noop_llseek, 1103 }; 1104 1105 static void sysrq_init_procfs(void) 1106 { 1107 if (!proc_create("sysrq-trigger", S_IWUSR, NULL, 1108 &proc_sysrq_trigger_operations)) 1109 pr_err("Failed to register proc interface\n"); 1110 } 1111 1112 #else 1113 1114 static inline void sysrq_init_procfs(void) 1115 { 1116 } 1117 1118 #endif /* CONFIG_PROC_FS */ 1119 1120 static int __init sysrq_init(void) 1121 { 1122 sysrq_init_procfs(); 1123 1124 if (sysrq_on()) 1125 sysrq_register_handler(); 1126 1127 return 0; 1128 } 1129 module_init(sysrq_init); 1130