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 mutex_lock(&oom_lock); 360 if (!out_of_memory(node_zonelist(first_memory_node, GFP_KERNEL), 361 GFP_KERNEL, 0, NULL, true)) 362 pr_info("OOM request ignored because killer is disabled\n"); 363 mutex_unlock(&oom_lock); 364 } 365 366 static DECLARE_WORK(moom_work, moom_callback); 367 368 static void sysrq_handle_moom(int key) 369 { 370 schedule_work(&moom_work); 371 } 372 static struct sysrq_key_op sysrq_moom_op = { 373 .handler = sysrq_handle_moom, 374 .help_msg = "memory-full-oom-kill(f)", 375 .action_msg = "Manual OOM execution", 376 .enable_mask = SYSRQ_ENABLE_SIGNAL, 377 }; 378 379 #ifdef CONFIG_BLOCK 380 static void sysrq_handle_thaw(int key) 381 { 382 emergency_thaw_all(); 383 } 384 static struct sysrq_key_op sysrq_thaw_op = { 385 .handler = sysrq_handle_thaw, 386 .help_msg = "thaw-filesystems(j)", 387 .action_msg = "Emergency Thaw of all frozen filesystems", 388 .enable_mask = SYSRQ_ENABLE_SIGNAL, 389 }; 390 #endif 391 392 static void sysrq_handle_kill(int key) 393 { 394 send_sig_all(SIGKILL); 395 console_loglevel = CONSOLE_LOGLEVEL_DEBUG; 396 } 397 static struct sysrq_key_op sysrq_kill_op = { 398 .handler = sysrq_handle_kill, 399 .help_msg = "kill-all-tasks(i)", 400 .action_msg = "Kill All Tasks", 401 .enable_mask = SYSRQ_ENABLE_SIGNAL, 402 }; 403 404 static void sysrq_handle_unrt(int key) 405 { 406 normalize_rt_tasks(); 407 } 408 static struct sysrq_key_op sysrq_unrt_op = { 409 .handler = sysrq_handle_unrt, 410 .help_msg = "nice-all-RT-tasks(n)", 411 .action_msg = "Nice All RT Tasks", 412 .enable_mask = SYSRQ_ENABLE_RTNICE, 413 }; 414 415 /* Key Operations table and lock */ 416 static DEFINE_SPINLOCK(sysrq_key_table_lock); 417 418 static struct sysrq_key_op *sysrq_key_table[36] = { 419 &sysrq_loglevel_op, /* 0 */ 420 &sysrq_loglevel_op, /* 1 */ 421 &sysrq_loglevel_op, /* 2 */ 422 &sysrq_loglevel_op, /* 3 */ 423 &sysrq_loglevel_op, /* 4 */ 424 &sysrq_loglevel_op, /* 5 */ 425 &sysrq_loglevel_op, /* 6 */ 426 &sysrq_loglevel_op, /* 7 */ 427 &sysrq_loglevel_op, /* 8 */ 428 &sysrq_loglevel_op, /* 9 */ 429 430 /* 431 * a: Don't use for system provided sysrqs, it is handled specially on 432 * sparc and will never arrive. 433 */ 434 NULL, /* a */ 435 &sysrq_reboot_op, /* b */ 436 &sysrq_crash_op, /* c & ibm_emac driver debug */ 437 &sysrq_showlocks_op, /* d */ 438 &sysrq_term_op, /* e */ 439 &sysrq_moom_op, /* f */ 440 /* g: May be registered for the kernel debugger */ 441 NULL, /* g */ 442 NULL, /* h - reserved for help */ 443 &sysrq_kill_op, /* i */ 444 #ifdef CONFIG_BLOCK 445 &sysrq_thaw_op, /* j */ 446 #else 447 NULL, /* j */ 448 #endif 449 &sysrq_SAK_op, /* k */ 450 #ifdef CONFIG_SMP 451 &sysrq_showallcpus_op, /* l */ 452 #else 453 NULL, /* l */ 454 #endif 455 &sysrq_showmem_op, /* m */ 456 &sysrq_unrt_op, /* n */ 457 /* o: This will often be registered as 'Off' at init time */ 458 NULL, /* o */ 459 &sysrq_showregs_op, /* p */ 460 &sysrq_show_timers_op, /* q */ 461 &sysrq_unraw_op, /* r */ 462 &sysrq_sync_op, /* s */ 463 &sysrq_showstate_op, /* t */ 464 &sysrq_mountro_op, /* u */ 465 /* v: May be registered for frame buffer console restore */ 466 NULL, /* v */ 467 &sysrq_showstate_blocked_op, /* w */ 468 /* x: May be registered on ppc/powerpc for xmon */ 469 /* x: May be registered on sparc64 for global PMU dump */ 470 NULL, /* x */ 471 /* y: May be registered on sparc64 for global register dump */ 472 NULL, /* y */ 473 &sysrq_ftrace_dump_op, /* z */ 474 }; 475 476 /* key2index calculation, -1 on invalid index */ 477 static int sysrq_key_table_key2index(int key) 478 { 479 int retval; 480 481 if ((key >= '0') && (key <= '9')) 482 retval = key - '0'; 483 else if ((key >= 'a') && (key <= 'z')) 484 retval = key + 10 - 'a'; 485 else 486 retval = -1; 487 return retval; 488 } 489 490 /* 491 * get and put functions for the table, exposed to modules. 492 */ 493 struct sysrq_key_op *__sysrq_get_key_op(int key) 494 { 495 struct sysrq_key_op *op_p = NULL; 496 int i; 497 498 i = sysrq_key_table_key2index(key); 499 if (i != -1) 500 op_p = sysrq_key_table[i]; 501 502 return op_p; 503 } 504 505 static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p) 506 { 507 int i = sysrq_key_table_key2index(key); 508 509 if (i != -1) 510 sysrq_key_table[i] = op_p; 511 } 512 513 void __handle_sysrq(int key, bool check_mask) 514 { 515 struct sysrq_key_op *op_p; 516 int orig_log_level; 517 int i; 518 519 rcu_sysrq_start(); 520 rcu_read_lock(); 521 /* 522 * Raise the apparent loglevel to maximum so that the sysrq header 523 * is shown to provide the user with positive feedback. We do not 524 * simply emit this at KERN_EMERG as that would change message 525 * routing in the consumers of /proc/kmsg. 526 */ 527 orig_log_level = console_loglevel; 528 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT; 529 pr_info("SysRq : "); 530 531 op_p = __sysrq_get_key_op(key); 532 if (op_p) { 533 /* 534 * Should we check for enabled operations (/proc/sysrq-trigger 535 * should not) and is the invoked operation enabled? 536 */ 537 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) { 538 pr_cont("%s\n", op_p->action_msg); 539 console_loglevel = orig_log_level; 540 op_p->handler(key); 541 } else { 542 pr_cont("This sysrq operation is disabled.\n"); 543 } 544 } else { 545 pr_cont("HELP : "); 546 /* Only print the help msg once per handler */ 547 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) { 548 if (sysrq_key_table[i]) { 549 int j; 550 551 for (j = 0; sysrq_key_table[i] != 552 sysrq_key_table[j]; j++) 553 ; 554 if (j != i) 555 continue; 556 pr_cont("%s ", sysrq_key_table[i]->help_msg); 557 } 558 } 559 pr_cont("\n"); 560 console_loglevel = orig_log_level; 561 } 562 rcu_read_unlock(); 563 rcu_sysrq_end(); 564 } 565 566 void handle_sysrq(int key) 567 { 568 if (sysrq_on()) 569 __handle_sysrq(key, true); 570 } 571 EXPORT_SYMBOL(handle_sysrq); 572 573 #ifdef CONFIG_INPUT 574 575 /* Simple translation table for the SysRq keys */ 576 static const unsigned char sysrq_xlate[KEY_CNT] = 577 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */ 578 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */ 579 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */ 580 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */ 581 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */ 582 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */ 583 "\r\000/"; /* 0x60 - 0x6f */ 584 585 struct sysrq_state { 586 struct input_handle handle; 587 struct work_struct reinject_work; 588 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)]; 589 unsigned int alt; 590 unsigned int alt_use; 591 bool active; 592 bool need_reinject; 593 bool reinjecting; 594 595 /* reset sequence handling */ 596 bool reset_canceled; 597 bool reset_requested; 598 unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)]; 599 int reset_seq_len; 600 int reset_seq_cnt; 601 int reset_seq_version; 602 struct timer_list keyreset_timer; 603 }; 604 605 #define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */ 606 static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX]; 607 static unsigned int sysrq_reset_seq_len; 608 static unsigned int sysrq_reset_seq_version = 1; 609 610 static void sysrq_parse_reset_sequence(struct sysrq_state *state) 611 { 612 int i; 613 unsigned short key; 614 615 state->reset_seq_cnt = 0; 616 617 for (i = 0; i < sysrq_reset_seq_len; i++) { 618 key = sysrq_reset_seq[i]; 619 620 if (key == KEY_RESERVED || key > KEY_MAX) 621 break; 622 623 __set_bit(key, state->reset_keybit); 624 state->reset_seq_len++; 625 626 if (test_bit(key, state->key_down)) 627 state->reset_seq_cnt++; 628 } 629 630 /* Disable reset until old keys are not released */ 631 state->reset_canceled = state->reset_seq_cnt != 0; 632 633 state->reset_seq_version = sysrq_reset_seq_version; 634 } 635 636 static void sysrq_do_reset(unsigned long _state) 637 { 638 struct sysrq_state *state = (struct sysrq_state *) _state; 639 640 state->reset_requested = true; 641 642 sys_sync(); 643 kernel_restart(NULL); 644 } 645 646 static void sysrq_handle_reset_request(struct sysrq_state *state) 647 { 648 if (state->reset_requested) 649 __handle_sysrq(sysrq_xlate[KEY_B], false); 650 651 if (sysrq_reset_downtime_ms) 652 mod_timer(&state->keyreset_timer, 653 jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms)); 654 else 655 sysrq_do_reset((unsigned long)state); 656 } 657 658 static void sysrq_detect_reset_sequence(struct sysrq_state *state, 659 unsigned int code, int value) 660 { 661 if (!test_bit(code, state->reset_keybit)) { 662 /* 663 * Pressing any key _not_ in reset sequence cancels 664 * the reset sequence. Also cancelling the timer in 665 * case additional keys were pressed after a reset 666 * has been requested. 667 */ 668 if (value && state->reset_seq_cnt) { 669 state->reset_canceled = true; 670 del_timer(&state->keyreset_timer); 671 } 672 } else if (value == 0) { 673 /* 674 * Key release - all keys in the reset sequence need 675 * to be pressed and held for the reset timeout 676 * to hold. 677 */ 678 del_timer(&state->keyreset_timer); 679 680 if (--state->reset_seq_cnt == 0) 681 state->reset_canceled = false; 682 } else if (value == 1) { 683 /* key press, not autorepeat */ 684 if (++state->reset_seq_cnt == state->reset_seq_len && 685 !state->reset_canceled) { 686 sysrq_handle_reset_request(state); 687 } 688 } 689 } 690 691 #ifdef CONFIG_OF 692 static void sysrq_of_get_keyreset_config(void) 693 { 694 u32 key; 695 struct device_node *np; 696 struct property *prop; 697 const __be32 *p; 698 699 np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq"); 700 if (!np) { 701 pr_debug("No sysrq node found"); 702 return; 703 } 704 705 /* Reset in case a __weak definition was present */ 706 sysrq_reset_seq_len = 0; 707 708 of_property_for_each_u32(np, "keyset", prop, p, key) { 709 if (key == KEY_RESERVED || key > KEY_MAX || 710 sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX) 711 break; 712 713 sysrq_reset_seq[sysrq_reset_seq_len++] = (unsigned short)key; 714 } 715 716 /* Get reset timeout if any. */ 717 of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms); 718 } 719 #else 720 static void sysrq_of_get_keyreset_config(void) 721 { 722 } 723 #endif 724 725 static void sysrq_reinject_alt_sysrq(struct work_struct *work) 726 { 727 struct sysrq_state *sysrq = 728 container_of(work, struct sysrq_state, reinject_work); 729 struct input_handle *handle = &sysrq->handle; 730 unsigned int alt_code = sysrq->alt_use; 731 732 if (sysrq->need_reinject) { 733 /* we do not want the assignment to be reordered */ 734 sysrq->reinjecting = true; 735 mb(); 736 737 /* Simulate press and release of Alt + SysRq */ 738 input_inject_event(handle, EV_KEY, alt_code, 1); 739 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1); 740 input_inject_event(handle, EV_SYN, SYN_REPORT, 1); 741 742 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0); 743 input_inject_event(handle, EV_KEY, alt_code, 0); 744 input_inject_event(handle, EV_SYN, SYN_REPORT, 1); 745 746 mb(); 747 sysrq->reinjecting = false; 748 } 749 } 750 751 static bool sysrq_handle_keypress(struct sysrq_state *sysrq, 752 unsigned int code, int value) 753 { 754 bool was_active = sysrq->active; 755 bool suppress; 756 757 switch (code) { 758 759 case KEY_LEFTALT: 760 case KEY_RIGHTALT: 761 if (!value) { 762 /* One of ALTs is being released */ 763 if (sysrq->active && code == sysrq->alt_use) 764 sysrq->active = false; 765 766 sysrq->alt = KEY_RESERVED; 767 768 } else if (value != 2) { 769 sysrq->alt = code; 770 sysrq->need_reinject = false; 771 } 772 break; 773 774 case KEY_SYSRQ: 775 if (value == 1 && sysrq->alt != KEY_RESERVED) { 776 sysrq->active = true; 777 sysrq->alt_use = sysrq->alt; 778 /* 779 * If nothing else will be pressed we'll need 780 * to re-inject Alt-SysRq keysroke. 781 */ 782 sysrq->need_reinject = true; 783 } 784 785 /* 786 * Pretend that sysrq was never pressed at all. This 787 * is needed to properly handle KGDB which will try 788 * to release all keys after exiting debugger. If we 789 * do not clear key bit it KGDB will end up sending 790 * release events for Alt and SysRq, potentially 791 * triggering print screen function. 792 */ 793 if (sysrq->active) 794 clear_bit(KEY_SYSRQ, sysrq->handle.dev->key); 795 796 break; 797 798 default: 799 if (sysrq->active && value && value != 2) { 800 sysrq->need_reinject = false; 801 __handle_sysrq(sysrq_xlate[code], true); 802 } 803 break; 804 } 805 806 suppress = sysrq->active; 807 808 if (!sysrq->active) { 809 810 /* 811 * See if reset sequence has changed since the last time. 812 */ 813 if (sysrq->reset_seq_version != sysrq_reset_seq_version) 814 sysrq_parse_reset_sequence(sysrq); 815 816 /* 817 * If we are not suppressing key presses keep track of 818 * keyboard state so we can release keys that have been 819 * pressed before entering SysRq mode. 820 */ 821 if (value) 822 set_bit(code, sysrq->key_down); 823 else 824 clear_bit(code, sysrq->key_down); 825 826 if (was_active) 827 schedule_work(&sysrq->reinject_work); 828 829 /* Check for reset sequence */ 830 sysrq_detect_reset_sequence(sysrq, code, value); 831 832 } else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) { 833 /* 834 * Pass on release events for keys that was pressed before 835 * entering SysRq mode. 836 */ 837 suppress = false; 838 } 839 840 return suppress; 841 } 842 843 static bool sysrq_filter(struct input_handle *handle, 844 unsigned int type, unsigned int code, int value) 845 { 846 struct sysrq_state *sysrq = handle->private; 847 bool suppress; 848 849 /* 850 * Do not filter anything if we are in the process of re-injecting 851 * Alt+SysRq combination. 852 */ 853 if (sysrq->reinjecting) 854 return false; 855 856 switch (type) { 857 858 case EV_SYN: 859 suppress = false; 860 break; 861 862 case EV_KEY: 863 suppress = sysrq_handle_keypress(sysrq, code, value); 864 break; 865 866 default: 867 suppress = sysrq->active; 868 break; 869 } 870 871 return suppress; 872 } 873 874 static int sysrq_connect(struct input_handler *handler, 875 struct input_dev *dev, 876 const struct input_device_id *id) 877 { 878 struct sysrq_state *sysrq; 879 int error; 880 881 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL); 882 if (!sysrq) 883 return -ENOMEM; 884 885 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq); 886 887 sysrq->handle.dev = dev; 888 sysrq->handle.handler = handler; 889 sysrq->handle.name = "sysrq"; 890 sysrq->handle.private = sysrq; 891 setup_timer(&sysrq->keyreset_timer, 892 sysrq_do_reset, (unsigned long)sysrq); 893 894 error = input_register_handle(&sysrq->handle); 895 if (error) { 896 pr_err("Failed to register input sysrq handler, error %d\n", 897 error); 898 goto err_free; 899 } 900 901 error = input_open_device(&sysrq->handle); 902 if (error) { 903 pr_err("Failed to open input device, error %d\n", error); 904 goto err_unregister; 905 } 906 907 return 0; 908 909 err_unregister: 910 input_unregister_handle(&sysrq->handle); 911 err_free: 912 kfree(sysrq); 913 return error; 914 } 915 916 static void sysrq_disconnect(struct input_handle *handle) 917 { 918 struct sysrq_state *sysrq = handle->private; 919 920 input_close_device(handle); 921 cancel_work_sync(&sysrq->reinject_work); 922 del_timer_sync(&sysrq->keyreset_timer); 923 input_unregister_handle(handle); 924 kfree(sysrq); 925 } 926 927 /* 928 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all 929 * keyboards have SysRq key predefined and so user may add it to keymap 930 * later, but we expect all such keyboards to have left alt. 931 */ 932 static const struct input_device_id sysrq_ids[] = { 933 { 934 .flags = INPUT_DEVICE_ID_MATCH_EVBIT | 935 INPUT_DEVICE_ID_MATCH_KEYBIT, 936 .evbit = { BIT_MASK(EV_KEY) }, 937 .keybit = { BIT_MASK(KEY_LEFTALT) }, 938 }, 939 { }, 940 }; 941 942 static struct input_handler sysrq_handler = { 943 .filter = sysrq_filter, 944 .connect = sysrq_connect, 945 .disconnect = sysrq_disconnect, 946 .name = "sysrq", 947 .id_table = sysrq_ids, 948 }; 949 950 static bool sysrq_handler_registered; 951 952 static inline void sysrq_register_handler(void) 953 { 954 unsigned short key; 955 int error; 956 int i; 957 958 /* First check if a __weak interface was instantiated. */ 959 for (i = 0; i < ARRAY_SIZE(sysrq_reset_seq); i++) { 960 key = platform_sysrq_reset_seq[i]; 961 if (key == KEY_RESERVED || key > KEY_MAX) 962 break; 963 964 sysrq_reset_seq[sysrq_reset_seq_len++] = key; 965 } 966 967 /* 968 * DT configuration takes precedence over anything that would 969 * have been defined via the __weak interface. 970 */ 971 sysrq_of_get_keyreset_config(); 972 973 error = input_register_handler(&sysrq_handler); 974 if (error) 975 pr_err("Failed to register input handler, error %d", error); 976 else 977 sysrq_handler_registered = true; 978 } 979 980 static inline void sysrq_unregister_handler(void) 981 { 982 if (sysrq_handler_registered) { 983 input_unregister_handler(&sysrq_handler); 984 sysrq_handler_registered = false; 985 } 986 } 987 988 static int sysrq_reset_seq_param_set(const char *buffer, 989 const struct kernel_param *kp) 990 { 991 unsigned long val; 992 int error; 993 994 error = kstrtoul(buffer, 0, &val); 995 if (error < 0) 996 return error; 997 998 if (val > KEY_MAX) 999 return -EINVAL; 1000 1001 *((unsigned short *)kp->arg) = val; 1002 sysrq_reset_seq_version++; 1003 1004 return 0; 1005 } 1006 1007 static struct kernel_param_ops param_ops_sysrq_reset_seq = { 1008 .get = param_get_ushort, 1009 .set = sysrq_reset_seq_param_set, 1010 }; 1011 1012 #define param_check_sysrq_reset_seq(name, p) \ 1013 __param_check(name, p, unsigned short) 1014 1015 module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq, 1016 &sysrq_reset_seq_len, 0644); 1017 1018 module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644); 1019 1020 #else 1021 1022 static inline void sysrq_register_handler(void) 1023 { 1024 } 1025 1026 static inline void sysrq_unregister_handler(void) 1027 { 1028 } 1029 1030 #endif /* CONFIG_INPUT */ 1031 1032 int sysrq_toggle_support(int enable_mask) 1033 { 1034 bool was_enabled = sysrq_on(); 1035 1036 sysrq_enabled = enable_mask; 1037 1038 if (was_enabled != sysrq_on()) { 1039 if (sysrq_on()) 1040 sysrq_register_handler(); 1041 else 1042 sysrq_unregister_handler(); 1043 } 1044 1045 return 0; 1046 } 1047 1048 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p, 1049 struct sysrq_key_op *remove_op_p) 1050 { 1051 int retval; 1052 1053 spin_lock(&sysrq_key_table_lock); 1054 if (__sysrq_get_key_op(key) == remove_op_p) { 1055 __sysrq_put_key_op(key, insert_op_p); 1056 retval = 0; 1057 } else { 1058 retval = -1; 1059 } 1060 spin_unlock(&sysrq_key_table_lock); 1061 1062 /* 1063 * A concurrent __handle_sysrq either got the old op or the new op. 1064 * Wait for it to go away before returning, so the code for an old 1065 * op is not freed (eg. on module unload) while it is in use. 1066 */ 1067 synchronize_rcu(); 1068 1069 return retval; 1070 } 1071 1072 int register_sysrq_key(int key, struct sysrq_key_op *op_p) 1073 { 1074 return __sysrq_swap_key_ops(key, op_p, NULL); 1075 } 1076 EXPORT_SYMBOL(register_sysrq_key); 1077 1078 int unregister_sysrq_key(int key, struct sysrq_key_op *op_p) 1079 { 1080 return __sysrq_swap_key_ops(key, NULL, op_p); 1081 } 1082 EXPORT_SYMBOL(unregister_sysrq_key); 1083 1084 #ifdef CONFIG_PROC_FS 1085 /* 1086 * writing 'C' to /proc/sysrq-trigger is like sysrq-C 1087 */ 1088 static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf, 1089 size_t count, loff_t *ppos) 1090 { 1091 if (count) { 1092 char c; 1093 1094 if (get_user(c, buf)) 1095 return -EFAULT; 1096 __handle_sysrq(c, false); 1097 } 1098 1099 return count; 1100 } 1101 1102 static const struct file_operations proc_sysrq_trigger_operations = { 1103 .write = write_sysrq_trigger, 1104 .llseek = noop_llseek, 1105 }; 1106 1107 static void sysrq_init_procfs(void) 1108 { 1109 if (!proc_create("sysrq-trigger", S_IWUSR, NULL, 1110 &proc_sysrq_trigger_operations)) 1111 pr_err("Failed to register proc interface\n"); 1112 } 1113 1114 #else 1115 1116 static inline void sysrq_init_procfs(void) 1117 { 1118 } 1119 1120 #endif /* CONFIG_PROC_FS */ 1121 1122 static int __init sysrq_init(void) 1123 { 1124 sysrq_init_procfs(); 1125 1126 if (sysrq_on()) 1127 sysrq_register_handler(); 1128 1129 return 0; 1130 } 1131 module_init(sysrq_init); 1132