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1// SPDX-License-Identifier: GPL-2.02/*3 * Linux Magic System Request Key Hacks4 *5 * (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>6 * based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz>7 *8 * (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>9 * overhauled to use key registration10 * based upon discusions in irc://irc.openprojects.net/#kernelnewbies11 *12 * Copyright (c) 2010 Dmitry Torokhov13 * Input handler conversion14 */15 16#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt17 18#include <linux/sched/signal.h>19#include <linux/sched/rt.h>20#include <linux/sched/debug.h>21#include <linux/sched/task.h>22#include <linux/ctype.h>23#include <linux/interrupt.h>24#include <linux/mm.h>25#include <linux/fs.h>26#include <linux/mount.h>27#include <linux/kdev_t.h>28#include <linux/major.h>29#include <linux/reboot.h>30#include <linux/sysrq.h>31#include <linux/kbd_kern.h>32#include <linux/proc_fs.h>33#include <linux/nmi.h>34#include <linux/quotaops.h>35#include <linux/perf_event.h>36#include <linux/kernel.h>37#include <linux/module.h>38#include <linux/suspend.h>39#include <linux/writeback.h>40#include <linux/swap.h>41#include <linux/spinlock.h>42#include <linux/vt_kern.h>43#include <linux/workqueue.h>44#include <linux/hrtimer.h>45#include <linux/oom.h>46#include <linux/slab.h>47#include <linux/input.h>48#include <linux/uaccess.h>49#include <linux/moduleparam.h>50#include <linux/jiffies.h>51#include <linux/syscalls.h>52#include <linux/of.h>53#include <linux/rcupdate.h>54 55#include <asm/ptrace.h>56#include <asm/irq_regs.h>57 58/* Whether we react on sysrq keys or just ignore them */59static int __read_mostly sysrq_enabled = CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE;60static bool __read_mostly sysrq_always_enabled;61 62static bool sysrq_on(void)63{64 return sysrq_enabled || sysrq_always_enabled;65}66 67/**68 * sysrq_mask - Getter for sysrq_enabled mask.69 *70 * Return: 1 if sysrq is always enabled, enabled sysrq_key_op mask otherwise.71 */72int sysrq_mask(void)73{74 if (sysrq_always_enabled)75 return 1;76 return sysrq_enabled;77}78EXPORT_SYMBOL_GPL(sysrq_mask);79 80/*81 * A value of 1 means 'all', other nonzero values are an op mask:82 */83static bool sysrq_on_mask(int mask)84{85 return sysrq_always_enabled ||86 sysrq_enabled == 1 ||87 (sysrq_enabled & mask);88}89 90static int __init sysrq_always_enabled_setup(char *str)91{92 sysrq_always_enabled = true;93 pr_info("sysrq always enabled.\n");94 95 return 1;96}97 98__setup("sysrq_always_enabled", sysrq_always_enabled_setup);99 100 101static void sysrq_handle_loglevel(u8 key)102{103 u8 loglevel = key - '0';104 105 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;106 pr_info("Loglevel set to %u\n", loglevel);107 console_loglevel = loglevel;108}109static const struct sysrq_key_op sysrq_loglevel_op = {110 .handler = sysrq_handle_loglevel,111 .help_msg = "loglevel(0-9)",112 .action_msg = "Changing Loglevel",113 .enable_mask = SYSRQ_ENABLE_LOG,114};115 116#ifdef CONFIG_VT117static void sysrq_handle_SAK(u8 key)118{119 struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;120 121 schedule_work(SAK_work);122}123static const struct sysrq_key_op sysrq_SAK_op = {124 .handler = sysrq_handle_SAK,125 .help_msg = "sak(k)",126 .action_msg = "SAK",127 .enable_mask = SYSRQ_ENABLE_KEYBOARD,128};129#else130#define sysrq_SAK_op (*(const struct sysrq_key_op *)NULL)131#endif132 133#ifdef CONFIG_VT134static void sysrq_handle_unraw(u8 key)135{136 vt_reset_unicode(fg_console);137}138 139static const struct sysrq_key_op sysrq_unraw_op = {140 .handler = sysrq_handle_unraw,141 .help_msg = "unraw(r)",142 .action_msg = "Keyboard mode set to system default",143 .enable_mask = SYSRQ_ENABLE_KEYBOARD,144};145#else146#define sysrq_unraw_op (*(const struct sysrq_key_op *)NULL)147#endif /* CONFIG_VT */148 149static void sysrq_handle_crash(u8 key)150{151 /* release the RCU read lock before crashing */152 rcu_read_unlock();153 154 panic("sysrq triggered crash\n");155}156static const struct sysrq_key_op sysrq_crash_op = {157 .handler = sysrq_handle_crash,158 .help_msg = "crash(c)",159 .action_msg = "Trigger a crash",160 .enable_mask = SYSRQ_ENABLE_DUMP,161};162 163static void sysrq_handle_reboot(u8 key)164{165 lockdep_off();166 local_irq_enable();167 emergency_restart();168}169static const struct sysrq_key_op sysrq_reboot_op = {170 .handler = sysrq_handle_reboot,171 .help_msg = "reboot(b)",172 .action_msg = "Resetting",173 .enable_mask = SYSRQ_ENABLE_BOOT,174};175 176const struct sysrq_key_op *__sysrq_reboot_op = &sysrq_reboot_op;177 178static void sysrq_handle_sync(u8 key)179{180 emergency_sync();181}182static const struct sysrq_key_op sysrq_sync_op = {183 .handler = sysrq_handle_sync,184 .help_msg = "sync(s)",185 .action_msg = "Emergency Sync",186 .enable_mask = SYSRQ_ENABLE_SYNC,187};188 189static void sysrq_handle_show_timers(u8 key)190{191 sysrq_timer_list_show();192}193 194static const struct sysrq_key_op sysrq_show_timers_op = {195 .handler = sysrq_handle_show_timers,196 .help_msg = "show-all-timers(q)",197 .action_msg = "Show clockevent devices & pending hrtimers (no others)",198};199 200static void sysrq_handle_mountro(u8 key)201{202 emergency_remount();203}204static const struct sysrq_key_op sysrq_mountro_op = {205 .handler = sysrq_handle_mountro,206 .help_msg = "unmount(u)",207 .action_msg = "Emergency Remount R/O",208 .enable_mask = SYSRQ_ENABLE_REMOUNT,209};210 211#ifdef CONFIG_LOCKDEP212static void sysrq_handle_showlocks(u8 key)213{214 debug_show_all_locks();215}216 217static const struct sysrq_key_op sysrq_showlocks_op = {218 .handler = sysrq_handle_showlocks,219 .help_msg = "show-all-locks(d)",220 .action_msg = "Show Locks Held",221};222#else223#define sysrq_showlocks_op (*(const struct sysrq_key_op *)NULL)224#endif225 226#ifdef CONFIG_SMP227static DEFINE_RAW_SPINLOCK(show_lock);228 229static void showacpu(void *dummy)230{231 unsigned long flags;232 233 /* Idle CPUs have no interesting backtrace. */234 if (idle_cpu(smp_processor_id())) {235 pr_info("CPU%d: backtrace skipped as idling\n", smp_processor_id());236 return;237 }238 239 raw_spin_lock_irqsave(&show_lock, flags);240 pr_info("CPU%d:\n", smp_processor_id());241 show_stack(NULL, NULL, KERN_INFO);242 raw_spin_unlock_irqrestore(&show_lock, flags);243}244 245static void sysrq_showregs_othercpus(struct work_struct *dummy)246{247 smp_call_function(showacpu, NULL, 0);248}249 250static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);251 252static void sysrq_handle_showallcpus(u8 key)253{254 /*255 * Fall back to the workqueue based printing if the256 * backtrace printing did not succeed or the257 * architecture has no support for it:258 */259 if (!trigger_all_cpu_backtrace()) {260 struct pt_regs *regs = NULL;261 262 if (in_hardirq())263 regs = get_irq_regs();264 265 pr_info("CPU%d:\n", get_cpu());266 if (regs)267 show_regs(regs);268 else269 show_stack(NULL, NULL, KERN_INFO);270 271 schedule_work(&sysrq_showallcpus);272 put_cpu();273 }274}275 276static const struct sysrq_key_op sysrq_showallcpus_op = {277 .handler = sysrq_handle_showallcpus,278 .help_msg = "show-backtrace-all-active-cpus(l)",279 .action_msg = "Show backtrace of all active CPUs",280 .enable_mask = SYSRQ_ENABLE_DUMP,281};282#else283#define sysrq_showallcpus_op (*(const struct sysrq_key_op *)NULL)284#endif285 286static void sysrq_handle_showregs(u8 key)287{288 struct pt_regs *regs = NULL;289 290 if (in_hardirq())291 regs = get_irq_regs();292 if (regs)293 show_regs(regs);294 perf_event_print_debug();295}296static const struct sysrq_key_op sysrq_showregs_op = {297 .handler = sysrq_handle_showregs,298 .help_msg = "show-registers(p)",299 .action_msg = "Show Regs",300 .enable_mask = SYSRQ_ENABLE_DUMP,301};302 303static void sysrq_handle_showstate(u8 key)304{305 show_state();306 show_all_workqueues();307}308static const struct sysrq_key_op sysrq_showstate_op = {309 .handler = sysrq_handle_showstate,310 .help_msg = "show-task-states(t)",311 .action_msg = "Show State",312 .enable_mask = SYSRQ_ENABLE_DUMP,313};314 315static void sysrq_handle_showstate_blocked(u8 key)316{317 show_state_filter(TASK_UNINTERRUPTIBLE);318}319static const struct sysrq_key_op sysrq_showstate_blocked_op = {320 .handler = sysrq_handle_showstate_blocked,321 .help_msg = "show-blocked-tasks(w)",322 .action_msg = "Show Blocked State",323 .enable_mask = SYSRQ_ENABLE_DUMP,324};325 326#ifdef CONFIG_TRACING327#include <linux/ftrace.h>328 329static void sysrq_ftrace_dump(u8 key)330{331 ftrace_dump(DUMP_ALL);332}333static const struct sysrq_key_op sysrq_ftrace_dump_op = {334 .handler = sysrq_ftrace_dump,335 .help_msg = "dump-ftrace-buffer(z)",336 .action_msg = "Dump ftrace buffer",337 .enable_mask = SYSRQ_ENABLE_DUMP,338};339#else340#define sysrq_ftrace_dump_op (*(const struct sysrq_key_op *)NULL)341#endif342 343static void sysrq_handle_showmem(u8 key)344{345 show_mem();346}347static const struct sysrq_key_op sysrq_showmem_op = {348 .handler = sysrq_handle_showmem,349 .help_msg = "show-memory-usage(m)",350 .action_msg = "Show Memory",351 .enable_mask = SYSRQ_ENABLE_DUMP,352};353 354/*355 * Signal sysrq helper function. Sends a signal to all user processes.356 */357static void send_sig_all(int sig)358{359 struct task_struct *p;360 361 read_lock(&tasklist_lock);362 for_each_process(p) {363 if (p->flags & PF_KTHREAD)364 continue;365 if (is_global_init(p))366 continue;367 368 do_send_sig_info(sig, SEND_SIG_PRIV, p, PIDTYPE_MAX);369 }370 read_unlock(&tasklist_lock);371}372 373static void sysrq_handle_term(u8 key)374{375 send_sig_all(SIGTERM);376 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;377}378static const struct sysrq_key_op sysrq_term_op = {379 .handler = sysrq_handle_term,380 .help_msg = "terminate-all-tasks(e)",381 .action_msg = "Terminate All Tasks",382 .enable_mask = SYSRQ_ENABLE_SIGNAL,383};384 385static void moom_callback(struct work_struct *ignored)386{387 const gfp_t gfp_mask = GFP_KERNEL;388 struct oom_control oc = {389 .zonelist = node_zonelist(first_memory_node, gfp_mask),390 .nodemask = NULL,391 .memcg = NULL,392 .gfp_mask = gfp_mask,393 .order = -1,394 };395 396 mutex_lock(&oom_lock);397 if (!out_of_memory(&oc))398 pr_info("OOM request ignored. No task eligible\n");399 mutex_unlock(&oom_lock);400}401 402static DECLARE_WORK(moom_work, moom_callback);403 404static void sysrq_handle_moom(u8 key)405{406 schedule_work(&moom_work);407}408static const struct sysrq_key_op sysrq_moom_op = {409 .handler = sysrq_handle_moom,410 .help_msg = "memory-full-oom-kill(f)",411 .action_msg = "Manual OOM execution",412 .enable_mask = SYSRQ_ENABLE_SIGNAL,413};414 415#ifdef CONFIG_BLOCK416static void sysrq_handle_thaw(u8 key)417{418 emergency_thaw_all();419}420static const struct sysrq_key_op sysrq_thaw_op = {421 .handler = sysrq_handle_thaw,422 .help_msg = "thaw-filesystems(j)",423 .action_msg = "Emergency Thaw of all frozen filesystems",424 .enable_mask = SYSRQ_ENABLE_SIGNAL,425};426#else427#define sysrq_thaw_op (*(const struct sysrq_key_op *)NULL)428#endif429 430static void sysrq_handle_kill(u8 key)431{432 send_sig_all(SIGKILL);433 console_loglevel = CONSOLE_LOGLEVEL_DEBUG;434}435static const struct sysrq_key_op sysrq_kill_op = {436 .handler = sysrq_handle_kill,437 .help_msg = "kill-all-tasks(i)",438 .action_msg = "Kill All Tasks",439 .enable_mask = SYSRQ_ENABLE_SIGNAL,440};441 442static void sysrq_handle_unrt(u8 key)443{444 normalize_rt_tasks();445}446static const struct sysrq_key_op sysrq_unrt_op = {447 .handler = sysrq_handle_unrt,448 .help_msg = "nice-all-RT-tasks(n)",449 .action_msg = "Nice All RT Tasks",450 .enable_mask = SYSRQ_ENABLE_RTNICE,451};452 453static void sysrq_handle_replay_logs(u8 key)454{455 console_try_replay_all();456}457static struct sysrq_key_op sysrq_replay_logs_op = {458 .handler = sysrq_handle_replay_logs,459 .help_msg = "replay-kernel-logs(R)",460 .action_msg = "Replay kernel logs on consoles",461 .enable_mask = SYSRQ_ENABLE_DUMP,462};463 464/* Key Operations table and lock */465static DEFINE_SPINLOCK(sysrq_key_table_lock);466 467static const struct sysrq_key_op *sysrq_key_table[62] = {468 &sysrq_loglevel_op, /* 0 */469 &sysrq_loglevel_op, /* 1 */470 &sysrq_loglevel_op, /* 2 */471 &sysrq_loglevel_op, /* 3 */472 &sysrq_loglevel_op, /* 4 */473 &sysrq_loglevel_op, /* 5 */474 &sysrq_loglevel_op, /* 6 */475 &sysrq_loglevel_op, /* 7 */476 &sysrq_loglevel_op, /* 8 */477 &sysrq_loglevel_op, /* 9 */478 479 /*480 * a: Don't use for system provided sysrqs, it is handled specially on481 * sparc and will never arrive.482 */483 NULL, /* a */484 &sysrq_reboot_op, /* b */485 &sysrq_crash_op, /* c */486 &sysrq_showlocks_op, /* d */487 &sysrq_term_op, /* e */488 &sysrq_moom_op, /* f */489 /* g: May be registered for the kernel debugger */490 NULL, /* g */491 NULL, /* h - reserved for help */492 &sysrq_kill_op, /* i */493 &sysrq_thaw_op, /* j */494 &sysrq_SAK_op, /* k */495 &sysrq_showallcpus_op, /* l */496 &sysrq_showmem_op, /* m */497 &sysrq_unrt_op, /* n */498 /* o: This will often be registered as 'Off' at init time */499 NULL, /* o */500 &sysrq_showregs_op, /* p */501 &sysrq_show_timers_op, /* q */502 &sysrq_unraw_op, /* r */503 &sysrq_sync_op, /* s */504 &sysrq_showstate_op, /* t */505 &sysrq_mountro_op, /* u */506 /* v: May be registered for frame buffer console restore */507 NULL, /* v */508 &sysrq_showstate_blocked_op, /* w */509 /* x: May be registered on mips for TLB dump */510 /* x: May be registered on ppc/powerpc for xmon */511 /* x: May be registered on sparc64 for global PMU dump */512 NULL, /* x */513 /* y: May be registered on sparc64 for global register dump */514 NULL, /* y */515 &sysrq_ftrace_dump_op, /* z */516 NULL, /* A */517 NULL, /* B */518 NULL, /* C */519 NULL, /* D */520 NULL, /* E */521 NULL, /* F */522 NULL, /* G */523 NULL, /* H */524 NULL, /* I */525 NULL, /* J */526 NULL, /* K */527 NULL, /* L */528 NULL, /* M */529 NULL, /* N */530 NULL, /* O */531 NULL, /* P */532 NULL, /* Q */533 &sysrq_replay_logs_op, /* R */534 /* S: May be registered by sched_ext for resetting */535 NULL, /* S */536 NULL, /* T */537 NULL, /* U */538 NULL, /* V */539 NULL, /* W */540 NULL, /* X */541 NULL, /* Y */542 NULL, /* Z */543};544 545/* key2index calculation, -1 on invalid index */546static int sysrq_key_table_key2index(u8 key)547{548 switch (key) {549 case '0' ... '9':550 return key - '0';551 case 'a' ... 'z':552 return key - 'a' + 10;553 case 'A' ... 'Z':554 return key - 'A' + 10 + 26;555 default:556 return -1;557 }558}559 560/*561 * get and put functions for the table, exposed to modules.562 */563static const struct sysrq_key_op *__sysrq_get_key_op(u8 key)564{565 const struct sysrq_key_op *op_p = NULL;566 int i;567 568 i = sysrq_key_table_key2index(key);569 if (i != -1)570 op_p = sysrq_key_table[i];571 572 return op_p;573}574 575static void __sysrq_put_key_op(u8 key, const struct sysrq_key_op *op_p)576{577 int i = sysrq_key_table_key2index(key);578 579 if (i != -1)580 sysrq_key_table[i] = op_p;581}582 583void __handle_sysrq(u8 key, bool check_mask)584{585 const struct sysrq_key_op *op_p;586 int orig_log_level;587 int orig_suppress_printk;588 int i;589 590 orig_suppress_printk = suppress_printk;591 suppress_printk = 0;592 593 rcu_sysrq_start();594 rcu_read_lock();595 /*596 * Raise the apparent loglevel to maximum so that the sysrq header597 * is shown to provide the user with positive feedback. We do not598 * simply emit this at KERN_EMERG as that would change message599 * routing in the consumers of /proc/kmsg.600 */601 orig_log_level = console_loglevel;602 console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;603 604 op_p = __sysrq_get_key_op(key);605 if (op_p) {606 /*607 * Should we check for enabled operations (/proc/sysrq-trigger608 * should not) and is the invoked operation enabled?609 */610 if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {611 pr_info("%s\n", op_p->action_msg);612 console_loglevel = orig_log_level;613 op_p->handler(key);614 } else {615 pr_info("This sysrq operation is disabled.\n");616 console_loglevel = orig_log_level;617 }618 } else {619 pr_info("HELP : ");620 /* Only print the help msg once per handler */621 for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) {622 if (sysrq_key_table[i]) {623 int j;624 625 for (j = 0; sysrq_key_table[i] !=626 sysrq_key_table[j]; j++)627 ;628 if (j != i)629 continue;630 pr_cont("%s ", sysrq_key_table[i]->help_msg);631 }632 }633 pr_cont("\n");634 console_loglevel = orig_log_level;635 }636 rcu_read_unlock();637 rcu_sysrq_end();638 639 suppress_printk = orig_suppress_printk;640}641 642void handle_sysrq(u8 key)643{644 if (sysrq_on())645 __handle_sysrq(key, true);646}647EXPORT_SYMBOL(handle_sysrq);648 649#ifdef CONFIG_INPUT650static int sysrq_reset_downtime_ms;651 652/* Simple translation table for the SysRq keys */653static const unsigned char sysrq_xlate[KEY_CNT] =654 "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */655 "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */656 "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */657 "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */658 "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */659 "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */660 "\r\000/"; /* 0x60 - 0x6f */661 662struct sysrq_state {663 struct input_handle handle;664 struct work_struct reinject_work;665 unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];666 unsigned int alt;667 unsigned int alt_use;668 unsigned int shift;669 unsigned int shift_use;670 bool active;671 bool need_reinject;672 bool reinjecting;673 674 /* reset sequence handling */675 bool reset_canceled;676 bool reset_requested;677 unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)];678 int reset_seq_len;679 int reset_seq_cnt;680 int reset_seq_version;681 struct timer_list keyreset_timer;682};683 684#define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */685static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX];686static unsigned int sysrq_reset_seq_len;687static unsigned int sysrq_reset_seq_version = 1;688 689static void sysrq_parse_reset_sequence(struct sysrq_state *state)690{691 int i;692 unsigned short key;693 694 state->reset_seq_cnt = 0;695 696 for (i = 0; i < sysrq_reset_seq_len; i++) {697 key = sysrq_reset_seq[i];698 699 if (key == KEY_RESERVED || key > KEY_MAX)700 break;701 702 __set_bit(key, state->reset_keybit);703 state->reset_seq_len++;704 705 if (test_bit(key, state->key_down))706 state->reset_seq_cnt++;707 }708 709 /* Disable reset until old keys are not released */710 state->reset_canceled = state->reset_seq_cnt != 0;711 712 state->reset_seq_version = sysrq_reset_seq_version;713}714 715static void sysrq_do_reset(struct timer_list *t)716{717 struct sysrq_state *state = from_timer(state, t, keyreset_timer);718 719 state->reset_requested = true;720 721 orderly_reboot();722}723 724static void sysrq_handle_reset_request(struct sysrq_state *state)725{726 if (state->reset_requested)727 __handle_sysrq(sysrq_xlate[KEY_B], false);728 729 if (sysrq_reset_downtime_ms)730 mod_timer(&state->keyreset_timer,731 jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms));732 else733 sysrq_do_reset(&state->keyreset_timer);734}735 736static void sysrq_detect_reset_sequence(struct sysrq_state *state,737 unsigned int code, int value)738{739 if (!test_bit(code, state->reset_keybit)) {740 /*741 * Pressing any key _not_ in reset sequence cancels742 * the reset sequence. Also cancelling the timer in743 * case additional keys were pressed after a reset744 * has been requested.745 */746 if (value && state->reset_seq_cnt) {747 state->reset_canceled = true;748 del_timer(&state->keyreset_timer);749 }750 } else if (value == 0) {751 /*752 * Key release - all keys in the reset sequence need753 * to be pressed and held for the reset timeout754 * to hold.755 */756 del_timer(&state->keyreset_timer);757 758 if (--state->reset_seq_cnt == 0)759 state->reset_canceled = false;760 } else if (value == 1) {761 /* key press, not autorepeat */762 if (++state->reset_seq_cnt == state->reset_seq_len &&763 !state->reset_canceled) {764 sysrq_handle_reset_request(state);765 }766 }767}768 769#ifdef CONFIG_OF770static void sysrq_of_get_keyreset_config(void)771{772 u32 key;773 struct device_node *np;774 775 np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq");776 if (!np) {777 pr_debug("No sysrq node found");778 return;779 }780 781 /* Reset in case a __weak definition was present */782 sysrq_reset_seq_len = 0;783 784 of_property_for_each_u32(np, "keyset", key) {785 if (key == KEY_RESERVED || key > KEY_MAX ||786 sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX)787 break;788 789 sysrq_reset_seq[sysrq_reset_seq_len++] = (unsigned short)key;790 }791 792 /* Get reset timeout if any. */793 of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms);794 795 of_node_put(np);796}797#else798static void sysrq_of_get_keyreset_config(void)799{800}801#endif802 803static void sysrq_reinject_alt_sysrq(struct work_struct *work)804{805 struct sysrq_state *sysrq =806 container_of(work, struct sysrq_state, reinject_work);807 struct input_handle *handle = &sysrq->handle;808 unsigned int alt_code = sysrq->alt_use;809 810 if (sysrq->need_reinject) {811 /* we do not want the assignment to be reordered */812 sysrq->reinjecting = true;813 mb();814 815 /* Simulate press and release of Alt + SysRq */816 input_inject_event(handle, EV_KEY, alt_code, 1);817 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);818 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);819 820 input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);821 input_inject_event(handle, EV_KEY, alt_code, 0);822 input_inject_event(handle, EV_SYN, SYN_REPORT, 1);823 824 mb();825 sysrq->reinjecting = false;826 }827}828 829static bool sysrq_handle_keypress(struct sysrq_state *sysrq,830 unsigned int code, int value)831{832 bool was_active = sysrq->active;833 bool suppress;834 835 switch (code) {836 837 case KEY_LEFTALT:838 case KEY_RIGHTALT:839 if (!value) {840 /* One of ALTs is being released */841 if (sysrq->active && code == sysrq->alt_use)842 sysrq->active = false;843 844 sysrq->alt = KEY_RESERVED;845 846 } else if (value != 2) {847 sysrq->alt = code;848 sysrq->need_reinject = false;849 }850 break;851 852 case KEY_LEFTSHIFT:853 case KEY_RIGHTSHIFT:854 if (!value)855 sysrq->shift = KEY_RESERVED;856 else if (value != 2)857 sysrq->shift = code;858 if (sysrq->active)859 sysrq->shift_use = sysrq->shift;860 break;861 862 case KEY_SYSRQ:863 if (value == 1 && sysrq->alt != KEY_RESERVED) {864 sysrq->active = true;865 sysrq->alt_use = sysrq->alt;866 /* either RESERVED (for released) or actual code */867 sysrq->shift_use = sysrq->shift;868 /*869 * If nothing else will be pressed we'll need870 * to re-inject Alt-SysRq keysroke.871 */872 sysrq->need_reinject = true;873 }874 875 /*876 * Pretend that sysrq was never pressed at all. This877 * is needed to properly handle KGDB which will try878 * to release all keys after exiting debugger. If we879 * do not clear key bit it KGDB will end up sending880 * release events for Alt and SysRq, potentially881 * triggering print screen function.882 */883 if (sysrq->active)884 clear_bit(KEY_SYSRQ, sysrq->handle.dev->key);885 886 break;887 888 default:889 if (sysrq->active && value && value != 2) {890 unsigned char c = sysrq_xlate[code];891 892 sysrq->need_reinject = false;893 if (sysrq->shift_use != KEY_RESERVED)894 c = toupper(c);895 __handle_sysrq(c, true);896 }897 break;898 }899 900 suppress = sysrq->active;901 902 if (!sysrq->active) {903 904 /*905 * See if reset sequence has changed since the last time.906 */907 if (sysrq->reset_seq_version != sysrq_reset_seq_version)908 sysrq_parse_reset_sequence(sysrq);909 910 /*911 * If we are not suppressing key presses keep track of912 * keyboard state so we can release keys that have been913 * pressed before entering SysRq mode.914 */915 if (value)916 set_bit(code, sysrq->key_down);917 else918 clear_bit(code, sysrq->key_down);919 920 if (was_active)921 schedule_work(&sysrq->reinject_work);922 923 /* Check for reset sequence */924 sysrq_detect_reset_sequence(sysrq, code, value);925 926 } else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) {927 /*928 * Pass on release events for keys that was pressed before929 * entering SysRq mode.930 */931 suppress = false;932 }933 934 return suppress;935}936 937static bool sysrq_filter(struct input_handle *handle,938 unsigned int type, unsigned int code, int value)939{940 struct sysrq_state *sysrq = handle->private;941 bool suppress;942 943 /*944 * Do not filter anything if we are in the process of re-injecting945 * Alt+SysRq combination.946 */947 if (sysrq->reinjecting)948 return false;949 950 switch (type) {951 952 case EV_SYN:953 suppress = false;954 break;955 956 case EV_KEY:957 suppress = sysrq_handle_keypress(sysrq, code, value);958 break;959 960 default:961 suppress = sysrq->active;962 break;963 }964 965 return suppress;966}967 968static int sysrq_connect(struct input_handler *handler,969 struct input_dev *dev,970 const struct input_device_id *id)971{972 struct sysrq_state *sysrq;973 int error;974 975 sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL);976 if (!sysrq)977 return -ENOMEM;978 979 INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq);980 981 sysrq->handle.dev = dev;982 sysrq->handle.handler = handler;983 sysrq->handle.name = "sysrq";984 sysrq->handle.private = sysrq;985 timer_setup(&sysrq->keyreset_timer, sysrq_do_reset, 0);986 987 error = input_register_handle(&sysrq->handle);988 if (error) {989 pr_err("Failed to register input sysrq handler, error %d\n",990 error);991 goto err_free;992 }993 994 error = input_open_device(&sysrq->handle);995 if (error) {996 pr_err("Failed to open input device, error %d\n", error);997 goto err_unregister;998 }999 1000 return 0;1001 1002 err_unregister:1003 input_unregister_handle(&sysrq->handle);1004 err_free:1005 kfree(sysrq);1006 return error;1007}1008 1009static void sysrq_disconnect(struct input_handle *handle)1010{1011 struct sysrq_state *sysrq = handle->private;1012 1013 input_close_device(handle);1014 cancel_work_sync(&sysrq->reinject_work);1015 timer_shutdown_sync(&sysrq->keyreset_timer);1016 input_unregister_handle(handle);1017 kfree(sysrq);1018}1019 1020/*1021 * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all1022 * keyboards have SysRq key predefined and so user may add it to keymap1023 * later, but we expect all such keyboards to have left alt.1024 */1025static const struct input_device_id sysrq_ids[] = {1026 {1027 .flags = INPUT_DEVICE_ID_MATCH_EVBIT |1028 INPUT_DEVICE_ID_MATCH_KEYBIT,1029 .evbit = { [BIT_WORD(EV_KEY)] = BIT_MASK(EV_KEY) },1030 .keybit = { [BIT_WORD(KEY_LEFTALT)] = BIT_MASK(KEY_LEFTALT) },1031 },1032 { },1033};1034 1035static struct input_handler sysrq_handler = {1036 .filter = sysrq_filter,1037 .connect = sysrq_connect,1038 .disconnect = sysrq_disconnect,1039 .name = "sysrq",1040 .id_table = sysrq_ids,1041};1042 1043static inline void sysrq_register_handler(void)1044{1045 int error;1046 1047 sysrq_of_get_keyreset_config();1048 1049 error = input_register_handler(&sysrq_handler);1050 if (error)1051 pr_err("Failed to register input handler, error %d", error);1052}1053 1054static inline void sysrq_unregister_handler(void)1055{1056 input_unregister_handler(&sysrq_handler);1057}1058 1059static int sysrq_reset_seq_param_set(const char *buffer,1060 const struct kernel_param *kp)1061{1062 unsigned long val;1063 int error;1064 1065 error = kstrtoul(buffer, 0, &val);1066 if (error < 0)1067 return error;1068 1069 if (val > KEY_MAX)1070 return -EINVAL;1071 1072 *((unsigned short *)kp->arg) = val;1073 sysrq_reset_seq_version++;1074 1075 return 0;1076}1077 1078static const struct kernel_param_ops param_ops_sysrq_reset_seq = {1079 .get = param_get_ushort,1080 .set = sysrq_reset_seq_param_set,1081};1082 1083#define param_check_sysrq_reset_seq(name, p) \1084 __param_check(name, p, unsigned short)1085 1086/*1087 * not really modular, but the easiest way to keep compat with existing1088 * bootargs behaviour is to continue using module_param here.1089 */1090module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq,1091 &sysrq_reset_seq_len, 0644);1092 1093module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644);1094 1095#else1096 1097static inline void sysrq_register_handler(void)1098{1099}1100 1101static inline void sysrq_unregister_handler(void)1102{1103}1104 1105#endif /* CONFIG_INPUT */1106 1107int sysrq_toggle_support(int enable_mask)1108{1109 bool was_enabled = sysrq_on();1110 1111 sysrq_enabled = enable_mask;1112 1113 if (was_enabled != sysrq_on()) {1114 if (sysrq_on())1115 sysrq_register_handler();1116 else1117 sysrq_unregister_handler();1118 }1119 1120 return 0;1121}1122EXPORT_SYMBOL_GPL(sysrq_toggle_support);1123 1124static int __sysrq_swap_key_ops(u8 key, const struct sysrq_key_op *insert_op_p,1125 const struct sysrq_key_op *remove_op_p)1126{1127 int retval;1128 1129 spin_lock(&sysrq_key_table_lock);1130 if (__sysrq_get_key_op(key) == remove_op_p) {1131 __sysrq_put_key_op(key, insert_op_p);1132 retval = 0;1133 } else {1134 retval = -1;1135 }1136 spin_unlock(&sysrq_key_table_lock);1137 1138 /*1139 * A concurrent __handle_sysrq either got the old op or the new op.1140 * Wait for it to go away before returning, so the code for an old1141 * op is not freed (eg. on module unload) while it is in use.1142 */1143 synchronize_rcu();1144 1145 return retval;1146}1147 1148int register_sysrq_key(u8 key, const struct sysrq_key_op *op_p)1149{1150 return __sysrq_swap_key_ops(key, op_p, NULL);1151}1152EXPORT_SYMBOL(register_sysrq_key);1153 1154int unregister_sysrq_key(u8 key, const struct sysrq_key_op *op_p)1155{1156 return __sysrq_swap_key_ops(key, NULL, op_p);1157}1158EXPORT_SYMBOL(unregister_sysrq_key);1159 1160#ifdef CONFIG_PROC_FS1161/*1162 * writing 'C' to /proc/sysrq-trigger is like sysrq-C1163 * Normally, only the first character written is processed.1164 * However, if the first character is an underscore,1165 * all characters are processed.1166 */1167static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,1168 size_t count, loff_t *ppos)1169{1170 bool bulk = false;1171 size_t i;1172 1173 for (i = 0; i < count; i++) {1174 char c;1175 1176 if (get_user(c, buf + i))1177 return -EFAULT;1178 1179 if (c == '_')1180 bulk = true;1181 else1182 __handle_sysrq(c, false);1183 1184 if (!bulk)1185 break;1186 }1187 1188 return count;1189}1190 1191static const struct proc_ops sysrq_trigger_proc_ops = {1192 .proc_write = write_sysrq_trigger,1193 .proc_lseek = noop_llseek,1194};1195 1196static void sysrq_init_procfs(void)1197{1198 if (!proc_create("sysrq-trigger", S_IWUSR, NULL,1199 &sysrq_trigger_proc_ops))1200 pr_err("Failed to register proc interface\n");1201}1202 1203#else1204 1205static inline void sysrq_init_procfs(void)1206{1207}1208 1209#endif /* CONFIG_PROC_FS */1210 1211static int __init sysrq_init(void)1212{1213 sysrq_init_procfs();1214 1215 if (sysrq_on())1216 sysrq_register_handler();1217 1218 return 0;1219}1220device_initcall(sysrq_init);1221