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 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 = CONSOLE_LOGLEVEL_DEFAULT; 90 pr_info("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 pr_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 pr_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 show_workqueue_state(); 276 } 277 static struct sysrq_key_op sysrq_showstate_op = { 278 .handler = sysrq_handle_showstate, 279 .help_msg = "show-task-states(t)", 280 .action_msg = "Show State", 281 .enable_mask = SYSRQ_ENABLE_DUMP, 282 }; 283 284 static void sysrq_handle_showstate_blocked(int key) 285 { 286 show_state_filter(TASK_UNINTERRUPTIBLE); 287 } 288 static struct sysrq_key_op sysrq_showstate_blocked_op = { 289 .handler = sysrq_handle_showstate_blocked, 290 .help_msg = "show-blocked-tasks(w)", 291 .action_msg = "Show Blocked State", 292 .enable_mask = SYSRQ_ENABLE_DUMP, 293 }; 294 295 #ifdef CONFIG_TRACING 296 #include <linux/ftrace.h> 297 298 static void sysrq_ftrace_dump(int key) 299 { 300 ftrace_dump(DUMP_ALL); 301 } 302 static struct sysrq_key_op sysrq_ftrace_dump_op = { 303 .handler = sysrq_ftrace_dump, 304 .help_msg = "dump-ftrace-buffer(z)", 305 .action_msg = "Dump ftrace buffer", 306 .enable_mask = SYSRQ_ENABLE_DUMP, 307 }; 308 #else 309 #define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL) 310 #endif 311 312 static void sysrq_handle_showmem(int key) 313 { 314 show_mem(0); 315 } 316 static struct sysrq_key_op sysrq_showmem_op = { 317 .handler = sysrq_handle_showmem, 318 .help_msg = "show-memory-usage(m)", 319 .action_msg = "Show Memory", 320 .enable_mask = SYSRQ_ENABLE_DUMP, 321 }; 322 323 /* 324 * Signal sysrq helper function. Sends a signal to all user processes. 325 */ 326 static void send_sig_all(int sig) 327 { 328 struct task_struct *p; 329 330 read_lock(&tasklist_lock); 331 for_each_process(p) { 332 if (p->flags & PF_KTHREAD) 333 continue; 334 if (is_global_init(p)) 335 continue; 336 337 do_send_sig_info(sig, SEND_SIG_FORCED, p, true); 338 } 339 read_unlock(&tasklist_lock); 340 } 341 342 static void sysrq_handle_term(int key) 343 { 344 send_sig_all(SIGTERM); 345 console_loglevel = CONSOLE_LOGLEVEL_DEBUG; 346 } 347 static struct sysrq_key_op sysrq_term_op = { 348 .handler = sysrq_handle_term, 349 .help_msg = "terminate-all-tasks(e)", 350 .action_msg = "Terminate All Tasks", 351 .enable_mask = SYSRQ_ENABLE_SIGNAL, 352 }; 353 354 static void moom_callback(struct work_struct *ignored) 355 { 356 mutex_lock(&oom_lock); 357 if (!out_of_memory(node_zonelist(first_memory_node, GFP_KERNEL), 358 GFP_KERNEL, 0, NULL, true)) 359 pr_info("OOM request ignored because killer is disabled\n"); 360 mutex_unlock(&oom_lock); 361 } 362 363 static DECLARE_WORK(moom_work, moom_callback); 364 365 static void sysrq_handle_moom(int key) 366 { 367 schedule_work(&moom_work); 368 } 369 static struct sysrq_key_op sysrq_moom_op = { 370 .handler = sysrq_handle_moom, 371 .help_msg = "memory-full-oom-kill(f)", 372 .action_msg = "Manual OOM execution", 373 .enable_mask = SYSRQ_ENABLE_SIGNAL, 374 }; 375 376 #ifdef CONFIG_BLOCK 377 static void sysrq_handle_thaw(int key) 378 { 379 emergency_thaw_all(); 380 } 381 static struct sysrq_key_op sysrq_thaw_op = { 382 .handler = sysrq_handle_thaw, 383 .help_msg = "thaw-filesystems(j)", 384 .action_msg = "Emergency Thaw of all frozen filesystems", 385 .enable_mask = SYSRQ_ENABLE_SIGNAL, 386 }; 387 #endif 388 389 static void sysrq_handle_kill(int key) 390 { 391 send_sig_all(SIGKILL); 392 console_loglevel = CONSOLE_LOGLEVEL_DEBUG; 393 } 394 static struct sysrq_key_op sysrq_kill_op = { 395 .handler = sysrq_handle_kill, 396 .help_msg = "kill-all-tasks(i)", 397 .action_msg = "Kill All Tasks", 398 .enable_mask = SYSRQ_ENABLE_SIGNAL, 399 }; 400 401 static void sysrq_handle_unrt(int key) 402 { 403 normalize_rt_tasks(); 404 } 405 static struct sysrq_key_op sysrq_unrt_op = { 406 .handler = sysrq_handle_unrt, 407 .help_msg = "nice-all-RT-tasks(n)", 408 .action_msg = "Nice All RT Tasks", 409 .enable_mask = SYSRQ_ENABLE_RTNICE, 410 }; 411 412 /* Key Operations table and lock */ 413 static DEFINE_SPINLOCK(sysrq_key_table_lock); 414 415 static struct sysrq_key_op *sysrq_key_table[36] = { 416 &sysrq_loglevel_op, /* 0 */ 417 &sysrq_loglevel_op, /* 1 */ 418 &sysrq_loglevel_op, /* 2 */ 419 &sysrq_loglevel_op, /* 3 */ 420 &sysrq_loglevel_op, /* 4 */ 421 &sysrq_loglevel_op, /* 5 */ 422 &sysrq_loglevel_op, /* 6 */ 423 &sysrq_loglevel_op, /* 7 */ 424 &sysrq_loglevel_op, /* 8 */ 425 &sysrq_loglevel_op, /* 9 */ 426 427 /* 428 * a: Don't use for system provided sysrqs, it is handled specially on 429 * sparc and will never arrive. 430 */ 431 NULL, /* a */ 432 &sysrq_reboot_op, /* b */ 433 &sysrq_crash_op, /* c & ibm_emac driver debug */ 434 &sysrq_showlocks_op, /* d */ 435 &sysrq_term_op, /* e */ 436 &sysrq_moom_op, /* f */ 437 /* g: May be registered for the kernel debugger */ 438 NULL, /* g */ 439 NULL, /* h - reserved for help */ 440 &sysrq_kill_op, /* i */ 441 #ifdef CONFIG_BLOCK 442 &sysrq_thaw_op, /* j */ 443 #else 444 NULL, /* j */ 445 #endif 446 &sysrq_SAK_op, /* k */ 447 #ifdef CONFIG_SMP 448 &sysrq_showallcpus_op, /* l */ 449 #else 450 NULL, /* l */ 451 #endif 452 &sysrq_showmem_op, /* m */ 453 &sysrq_unrt_op, /* n */ 454 /* o: This will often be registered as 'Off' at init time */ 455 NULL, /* o */ 456 &sysrq_showregs_op, /* p */ 457 &sysrq_show_timers_op, /* q */ 458 &sysrq_unraw_op, /* r */ 459 &sysrq_sync_op, /* s */ 460 &sysrq_showstate_op, /* t */ 461 &sysrq_mountro_op, /* u */ 462 /* v: May be registered for frame buffer console restore */ 463 NULL, /* v */ 464 &sysrq_showstate_blocked_op, /* w */ 465 /* x: May be registered on mips for TLB dump */ 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 static int sysrq_reset_downtime_ms; 573 574 /* Simple translation table for the SysRq keys */ 575 static const unsigned char sysrq_xlate[KEY_CNT] = 576 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */ 577 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */ 578 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */ 579 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */ 580 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */ 581 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */ 582 "\r\000/"; /* 0x60 - 0x6f */ 583 584 struct sysrq_state { 585 struct input_handle handle; 586 struct work_struct reinject_work; 587 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)]; 588 unsigned int alt; 589 unsigned int alt_use; 590 bool active; 591 bool need_reinject; 592 bool reinjecting; 593 594 /* reset sequence handling */ 595 bool reset_canceled; 596 bool reset_requested; 597 unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)]; 598 int reset_seq_len; 599 int reset_seq_cnt; 600 int reset_seq_version; 601 struct timer_list keyreset_timer; 602 }; 603 604 #define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */ 605 static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX]; 606 static unsigned int sysrq_reset_seq_len; 607 static unsigned int sysrq_reset_seq_version = 1; 608 609 static void sysrq_parse_reset_sequence(struct sysrq_state *state) 610 { 611 int i; 612 unsigned short key; 613 614 state->reset_seq_cnt = 0; 615 616 for (i = 0; i < sysrq_reset_seq_len; i++) { 617 key = sysrq_reset_seq[i]; 618 619 if (key == KEY_RESERVED || key > KEY_MAX) 620 break; 621 622 __set_bit(key, state->reset_keybit); 623 state->reset_seq_len++; 624 625 if (test_bit(key, state->key_down)) 626 state->reset_seq_cnt++; 627 } 628 629 /* Disable reset until old keys are not released */ 630 state->reset_canceled = state->reset_seq_cnt != 0; 631 632 state->reset_seq_version = sysrq_reset_seq_version; 633 } 634 635 static void sysrq_do_reset(unsigned long _state) 636 { 637 struct sysrq_state *state = (struct sysrq_state *) _state; 638 639 state->reset_requested = true; 640 641 sys_sync(); 642 kernel_restart(NULL); 643 } 644 645 static void sysrq_handle_reset_request(struct sysrq_state *state) 646 { 647 if (state->reset_requested) 648 __handle_sysrq(sysrq_xlate[KEY_B], false); 649 650 if (sysrq_reset_downtime_ms) 651 mod_timer(&state->keyreset_timer, 652 jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms)); 653 else 654 sysrq_do_reset((unsigned long)state); 655 } 656 657 static void sysrq_detect_reset_sequence(struct sysrq_state *state, 658 unsigned int code, int value) 659 { 660 if (!test_bit(code, state->reset_keybit)) { 661 /* 662 * Pressing any key _not_ in reset sequence cancels 663 * the reset sequence. Also cancelling the timer in 664 * case additional keys were pressed after a reset 665 * has been requested. 666 */ 667 if (value && state->reset_seq_cnt) { 668 state->reset_canceled = true; 669 del_timer(&state->keyreset_timer); 670 } 671 } else if (value == 0) { 672 /* 673 * Key release - all keys in the reset sequence need 674 * to be pressed and held for the reset timeout 675 * to hold. 676 */ 677 del_timer(&state->keyreset_timer); 678 679 if (--state->reset_seq_cnt == 0) 680 state->reset_canceled = false; 681 } else if (value == 1) { 682 /* key press, not autorepeat */ 683 if (++state->reset_seq_cnt == state->reset_seq_len && 684 !state->reset_canceled) { 685 sysrq_handle_reset_request(state); 686 } 687 } 688 } 689 690 #ifdef CONFIG_OF 691 static void sysrq_of_get_keyreset_config(void) 692 { 693 u32 key; 694 struct device_node *np; 695 struct property *prop; 696 const __be32 *p; 697 698 np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq"); 699 if (!np) { 700 pr_debug("No sysrq node found"); 701 return; 702 } 703 704 /* Reset in case a __weak definition was present */ 705 sysrq_reset_seq_len = 0; 706 707 of_property_for_each_u32(np, "keyset", prop, p, key) { 708 if (key == KEY_RESERVED || key > KEY_MAX || 709 sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX) 710 break; 711 712 sysrq_reset_seq[sysrq_reset_seq_len++] = (unsigned short)key; 713 } 714 715 /* Get reset timeout if any. */ 716 of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms); 717 } 718 #else 719 static void sysrq_of_get_keyreset_config(void) 720 { 721 } 722 #endif 723 724 static void sysrq_reinject_alt_sysrq(struct work_struct *work) 725 { 726 struct sysrq_state *sysrq = 727 container_of(work, struct sysrq_state, reinject_work); 728 struct input_handle *handle = &sysrq->handle; 729 unsigned int alt_code = sysrq->alt_use; 730 731 if (sysrq->need_reinject) { 732 /* we do not want the assignment to be reordered */ 733 sysrq->reinjecting = true; 734 mb(); 735 736 /* Simulate press and release of Alt + SysRq */ 737 input_inject_event(handle, EV_KEY, alt_code, 1); 738 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1); 739 input_inject_event(handle, EV_SYN, SYN_REPORT, 1); 740 741 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0); 742 input_inject_event(handle, EV_KEY, alt_code, 0); 743 input_inject_event(handle, EV_SYN, SYN_REPORT, 1); 744 745 mb(); 746 sysrq->reinjecting = false; 747 } 748 } 749 750 static bool sysrq_handle_keypress(struct sysrq_state *sysrq, 751 unsigned int code, int value) 752 { 753 bool was_active = sysrq->active; 754 bool suppress; 755 756 switch (code) { 757 758 case KEY_LEFTALT: 759 case KEY_RIGHTALT: 760 if (!value) { 761 /* One of ALTs is being released */ 762 if (sysrq->active && code == sysrq->alt_use) 763 sysrq->active = false; 764 765 sysrq->alt = KEY_RESERVED; 766 767 } else if (value != 2) { 768 sysrq->alt = code; 769 sysrq->need_reinject = false; 770 } 771 break; 772 773 case KEY_SYSRQ: 774 if (value == 1 && sysrq->alt != KEY_RESERVED) { 775 sysrq->active = true; 776 sysrq->alt_use = sysrq->alt; 777 /* 778 * If nothing else will be pressed we'll need 779 * to re-inject Alt-SysRq keysroke. 780 */ 781 sysrq->need_reinject = true; 782 } 783 784 /* 785 * Pretend that sysrq was never pressed at all. This 786 * is needed to properly handle KGDB which will try 787 * to release all keys after exiting debugger. If we 788 * do not clear key bit it KGDB will end up sending 789 * release events for Alt and SysRq, potentially 790 * triggering print screen function. 791 */ 792 if (sysrq->active) 793 clear_bit(KEY_SYSRQ, sysrq->handle.dev->key); 794 795 break; 796 797 default: 798 if (sysrq->active && value && value != 2) { 799 sysrq->need_reinject = false; 800 __handle_sysrq(sysrq_xlate[code], true); 801 } 802 break; 803 } 804 805 suppress = sysrq->active; 806 807 if (!sysrq->active) { 808 809 /* 810 * See if reset sequence has changed since the last time. 811 */ 812 if (sysrq->reset_seq_version != sysrq_reset_seq_version) 813 sysrq_parse_reset_sequence(sysrq); 814 815 /* 816 * If we are not suppressing key presses keep track of 817 * keyboard state so we can release keys that have been 818 * pressed before entering SysRq mode. 819 */ 820 if (value) 821 set_bit(code, sysrq->key_down); 822 else 823 clear_bit(code, sysrq->key_down); 824 825 if (was_active) 826 schedule_work(&sysrq->reinject_work); 827 828 /* Check for reset sequence */ 829 sysrq_detect_reset_sequence(sysrq, code, value); 830 831 } else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) { 832 /* 833 * Pass on release events for keys that was pressed before 834 * entering SysRq mode. 835 */ 836 suppress = false; 837 } 838 839 return suppress; 840 } 841 842 static bool sysrq_filter(struct input_handle *handle, 843 unsigned int type, unsigned int code, int value) 844 { 845 struct sysrq_state *sysrq = handle->private; 846 bool suppress; 847 848 /* 849 * Do not filter anything if we are in the process of re-injecting 850 * Alt+SysRq combination. 851 */ 852 if (sysrq->reinjecting) 853 return false; 854 855 switch (type) { 856 857 case EV_SYN: 858 suppress = false; 859 break; 860 861 case EV_KEY: 862 suppress = sysrq_handle_keypress(sysrq, code, value); 863 break; 864 865 default: 866 suppress = sysrq->active; 867 break; 868 } 869 870 return suppress; 871 } 872 873 static int sysrq_connect(struct input_handler *handler, 874 struct input_dev *dev, 875 const struct input_device_id *id) 876 { 877 struct sysrq_state *sysrq; 878 int error; 879 880 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL); 881 if (!sysrq) 882 return -ENOMEM; 883 884 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq); 885 886 sysrq->handle.dev = dev; 887 sysrq->handle.handler = handler; 888 sysrq->handle.name = "sysrq"; 889 sysrq->handle.private = sysrq; 890 setup_timer(&sysrq->keyreset_timer, 891 sysrq_do_reset, (unsigned long)sysrq); 892 893 error = input_register_handle(&sysrq->handle); 894 if (error) { 895 pr_err("Failed to register input sysrq handler, error %d\n", 896 error); 897 goto err_free; 898 } 899 900 error = input_open_device(&sysrq->handle); 901 if (error) { 902 pr_err("Failed to open input device, error %d\n", error); 903 goto err_unregister; 904 } 905 906 return 0; 907 908 err_unregister: 909 input_unregister_handle(&sysrq->handle); 910 err_free: 911 kfree(sysrq); 912 return error; 913 } 914 915 static void sysrq_disconnect(struct input_handle *handle) 916 { 917 struct sysrq_state *sysrq = handle->private; 918 919 input_close_device(handle); 920 cancel_work_sync(&sysrq->reinject_work); 921 del_timer_sync(&sysrq->keyreset_timer); 922 input_unregister_handle(handle); 923 kfree(sysrq); 924 } 925 926 /* 927 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all 928 * keyboards have SysRq key predefined and so user may add it to keymap 929 * later, but we expect all such keyboards to have left alt. 930 */ 931 static const struct input_device_id sysrq_ids[] = { 932 { 933 .flags = INPUT_DEVICE_ID_MATCH_EVBIT | 934 INPUT_DEVICE_ID_MATCH_KEYBIT, 935 .evbit = { BIT_MASK(EV_KEY) }, 936 .keybit = { BIT_MASK(KEY_LEFTALT) }, 937 }, 938 { }, 939 }; 940 941 static struct input_handler sysrq_handler = { 942 .filter = sysrq_filter, 943 .connect = sysrq_connect, 944 .disconnect = sysrq_disconnect, 945 .name = "sysrq", 946 .id_table = sysrq_ids, 947 }; 948 949 static bool sysrq_handler_registered; 950 951 static inline void sysrq_register_handler(void) 952 { 953 int error; 954 955 sysrq_of_get_keyreset_config(); 956 957 error = input_register_handler(&sysrq_handler); 958 if (error) 959 pr_err("Failed to register input handler, error %d", error); 960 else 961 sysrq_handler_registered = true; 962 } 963 964 static inline void sysrq_unregister_handler(void) 965 { 966 if (sysrq_handler_registered) { 967 input_unregister_handler(&sysrq_handler); 968 sysrq_handler_registered = false; 969 } 970 } 971 972 static int sysrq_reset_seq_param_set(const char *buffer, 973 const struct kernel_param *kp) 974 { 975 unsigned long val; 976 int error; 977 978 error = kstrtoul(buffer, 0, &val); 979 if (error < 0) 980 return error; 981 982 if (val > KEY_MAX) 983 return -EINVAL; 984 985 *((unsigned short *)kp->arg) = val; 986 sysrq_reset_seq_version++; 987 988 return 0; 989 } 990 991 static const struct kernel_param_ops param_ops_sysrq_reset_seq = { 992 .get = param_get_ushort, 993 .set = sysrq_reset_seq_param_set, 994 }; 995 996 #define param_check_sysrq_reset_seq(name, p) \ 997 __param_check(name, p, unsigned short) 998 999 module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq, 1000 &sysrq_reset_seq_len, 0644); 1001 1002 module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644); 1003 1004 #else 1005 1006 static inline void sysrq_register_handler(void) 1007 { 1008 } 1009 1010 static inline void sysrq_unregister_handler(void) 1011 { 1012 } 1013 1014 #endif /* CONFIG_INPUT */ 1015 1016 int sysrq_toggle_support(int enable_mask) 1017 { 1018 bool was_enabled = sysrq_on(); 1019 1020 sysrq_enabled = enable_mask; 1021 1022 if (was_enabled != sysrq_on()) { 1023 if (sysrq_on()) 1024 sysrq_register_handler(); 1025 else 1026 sysrq_unregister_handler(); 1027 } 1028 1029 return 0; 1030 } 1031 1032 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p, 1033 struct sysrq_key_op *remove_op_p) 1034 { 1035 int retval; 1036 1037 spin_lock(&sysrq_key_table_lock); 1038 if (__sysrq_get_key_op(key) == remove_op_p) { 1039 __sysrq_put_key_op(key, insert_op_p); 1040 retval = 0; 1041 } else { 1042 retval = -1; 1043 } 1044 spin_unlock(&sysrq_key_table_lock); 1045 1046 /* 1047 * A concurrent __handle_sysrq either got the old op or the new op. 1048 * Wait for it to go away before returning, so the code for an old 1049 * op is not freed (eg. on module unload) while it is in use. 1050 */ 1051 synchronize_rcu(); 1052 1053 return retval; 1054 } 1055 1056 int register_sysrq_key(int key, struct sysrq_key_op *op_p) 1057 { 1058 return __sysrq_swap_key_ops(key, op_p, NULL); 1059 } 1060 EXPORT_SYMBOL(register_sysrq_key); 1061 1062 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p) 1063 { 1064 return __sysrq_swap_key_ops(key, NULL, op_p); 1065 } 1066 EXPORT_SYMBOL(unregister_sysrq_key); 1067 1068 #ifdef CONFIG_PROC_FS 1069 /* 1070 * writing 'C' to /proc/sysrq-trigger is like sysrq-C 1071 */ 1072 static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf, 1073 size_t count, loff_t *ppos) 1074 { 1075 if (count) { 1076 char c; 1077 1078 if (get_user(c, buf)) 1079 return -EFAULT; 1080 __handle_sysrq(c, false); 1081 } 1082 1083 return count; 1084 } 1085 1086 static const struct file_operations proc_sysrq_trigger_operations = { 1087 .write = write_sysrq_trigger, 1088 .llseek = noop_llseek, 1089 }; 1090 1091 static void sysrq_init_procfs(void) 1092 { 1093 if (!proc_create("sysrq-trigger", S_IWUSR, NULL, 1094 &proc_sysrq_trigger_operations)) 1095 pr_err("Failed to register proc interface\n"); 1096 } 1097 1098 #else 1099 1100 static inline void sysrq_init_procfs(void) 1101 { 1102 } 1103 1104 #endif /* CONFIG_PROC_FS */ 1105 1106 static int __init sysrq_init(void) 1107 { 1108 sysrq_init_procfs(); 1109 1110 if (sysrq_on()) 1111 sysrq_register_handler(); 1112 1113 return 0; 1114 } 1115 module_init(sysrq_init); 1116