// SPDX-License-Identifier: GPL-2.0 /* * Linux Magic System Request Key Hacks * * (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz> * based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz> * * (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com> * overhauled to use key registration * based upon discusions in irc://irc.openprojects.net/#kernelnewbies * * Copyright (c) 2010 Dmitry Torokhov * Input handler conversion */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/sched/signal.h> #include <linux/sched/rt.h> #include <linux/sched/debug.h> #include <linux/sched/task.h> #include <linux/interrupt.h> #include <linux/mm.h> #include <linux/fs.h> #include <linux/mount.h> #include <linux/kdev_t.h> #include <linux/major.h> #include <linux/reboot.h> #include <linux/sysrq.h> #include <linux/kbd_kern.h> #include <linux/proc_fs.h> #include <linux/nmi.h> #include <linux/quotaops.h> #include <linux/perf_event.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/suspend.h> #include <linux/writeback.h> #include <linux/swap.h> #include <linux/spinlock.h> #include <linux/vt_kern.h> #include <linux/workqueue.h> #include <linux/hrtimer.h> #include <linux/oom.h> #include <linux/slab.h> #include <linux/input.h> #include <linux/uaccess.h> #include <linux/moduleparam.h> #include <linux/jiffies.h> #include <linux/syscalls.h> #include <linux/of.h> #include <linux/rcupdate.h> #include <asm/ptrace.h> #include <asm/irq_regs.h> /* Whether we react on sysrq keys or just ignore them */ static int __read_mostly sysrq_enabled = CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE; static bool __read_mostly sysrq_always_enabled; static bool sysrq_on(void) { return sysrq_enabled || sysrq_always_enabled; } /* * A value of 1 means 'all', other nonzero values are an op mask: */ static bool sysrq_on_mask(int mask) { return sysrq_always_enabled || sysrq_enabled == 1 || (sysrq_enabled & mask); } static int __init sysrq_always_enabled_setup(char *str) { sysrq_always_enabled = true; pr_info("sysrq always enabled.\n"); return 1; } __setup("sysrq_always_enabled", sysrq_always_enabled_setup); static void sysrq_handle_loglevel(int key) { int i; i = key - '0'; console_loglevel = CONSOLE_LOGLEVEL_DEFAULT; pr_info("Loglevel set to %d\n", i); console_loglevel = i; } static struct sysrq_key_op sysrq_loglevel_op = { .handler = sysrq_handle_loglevel, .help_msg = "loglevel(0-9)", .action_msg = "Changing Loglevel", .enable_mask = SYSRQ_ENABLE_LOG, }; #ifdef CONFIG_VT static void sysrq_handle_SAK(int key) { struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work; schedule_work(SAK_work); } static struct sysrq_key_op sysrq_SAK_op = { .handler = sysrq_handle_SAK, .help_msg = "sak(k)", .action_msg = "SAK", .enable_mask = SYSRQ_ENABLE_KEYBOARD, }; #else #define sysrq_SAK_op (*(struct sysrq_key_op *)NULL) #endif #ifdef CONFIG_VT static void sysrq_handle_unraw(int key) { vt_reset_unicode(fg_console); } static struct sysrq_key_op sysrq_unraw_op = { .handler = sysrq_handle_unraw, .help_msg = "unraw(r)", .action_msg = "Keyboard mode set to system default", .enable_mask = SYSRQ_ENABLE_KEYBOARD, }; #else #define sysrq_unraw_op (*(struct sysrq_key_op *)NULL) #endif /* CONFIG_VT */ static void sysrq_handle_crash(int key) { /* release the RCU read lock before crashing */ rcu_read_unlock(); panic("sysrq triggered crash\n"); } static struct sysrq_key_op sysrq_crash_op = { .handler = sysrq_handle_crash, .help_msg = "crash(c)", .action_msg = "Trigger a crash", .enable_mask = SYSRQ_ENABLE_DUMP, }; static void sysrq_handle_reboot(int key) { lockdep_off(); local_irq_enable(); emergency_restart(); } static struct sysrq_key_op sysrq_reboot_op = { .handler = sysrq_handle_reboot, .help_msg = "reboot(b)", .action_msg = "Resetting", .enable_mask = SYSRQ_ENABLE_BOOT, }; static void sysrq_handle_sync(int key) { emergency_sync(); } static struct sysrq_key_op sysrq_sync_op = { .handler = sysrq_handle_sync, .help_msg = "sync(s)", .action_msg = "Emergency Sync", .enable_mask = SYSRQ_ENABLE_SYNC, }; static void sysrq_handle_show_timers(int key) { sysrq_timer_list_show(); } static struct sysrq_key_op sysrq_show_timers_op = { .handler = sysrq_handle_show_timers, .help_msg = "show-all-timers(q)", .action_msg = "Show clockevent devices & pending hrtimers (no others)", }; static void sysrq_handle_mountro(int key) { emergency_remount(); } static struct sysrq_key_op sysrq_mountro_op = { .handler = sysrq_handle_mountro, .help_msg = "unmount(u)", .action_msg = "Emergency Remount R/O", .enable_mask = SYSRQ_ENABLE_REMOUNT, }; #ifdef CONFIG_LOCKDEP static void sysrq_handle_showlocks(int key) { debug_show_all_locks(); } static struct sysrq_key_op sysrq_showlocks_op = { .handler = sysrq_handle_showlocks, .help_msg = "show-all-locks(d)", .action_msg = "Show Locks Held", }; #else #define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL) #endif #ifdef CONFIG_SMP static DEFINE_RAW_SPINLOCK(show_lock); static void showacpu(void *dummy) { unsigned long flags; /* Idle CPUs have no interesting backtrace. */ if (idle_cpu(smp_processor_id())) return; raw_spin_lock_irqsave(&show_lock, flags); pr_info("CPU%d:\n", smp_processor_id()); show_stack(NULL, NULL); raw_spin_unlock_irqrestore(&show_lock, flags); } static void sysrq_showregs_othercpus(struct work_struct *dummy) { smp_call_function(showacpu, NULL, 0); } static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus); static void sysrq_handle_showallcpus(int key) { /* * Fall back to the workqueue based printing if the * backtrace printing did not succeed or the * architecture has no support for it: */ if (!trigger_all_cpu_backtrace()) { struct pt_regs *regs = NULL; if (in_irq()) regs = get_irq_regs(); if (regs) { pr_info("CPU%d:\n", smp_processor_id()); show_regs(regs); } schedule_work(&sysrq_showallcpus); } } static struct sysrq_key_op sysrq_showallcpus_op = { .handler = sysrq_handle_showallcpus, .help_msg = "show-backtrace-all-active-cpus(l)", .action_msg = "Show backtrace of all active CPUs", .enable_mask = SYSRQ_ENABLE_DUMP, }; #endif static void sysrq_handle_showregs(int key) { struct pt_regs *regs = NULL; if (in_irq()) regs = get_irq_regs(); if (regs) show_regs(regs); perf_event_print_debug(); } static struct sysrq_key_op sysrq_showregs_op = { .handler = sysrq_handle_showregs, .help_msg = "show-registers(p)", .action_msg = "Show Regs", .enable_mask = SYSRQ_ENABLE_DUMP, }; static void sysrq_handle_showstate(int key) { show_state(); show_workqueue_state(); } static struct sysrq_key_op sysrq_showstate_op = { .handler = sysrq_handle_showstate, .help_msg = "show-task-states(t)", .action_msg = "Show State", .enable_mask = SYSRQ_ENABLE_DUMP, }; static void sysrq_handle_showstate_blocked(int key) { show_state_filter(TASK_UNINTERRUPTIBLE); } static struct sysrq_key_op sysrq_showstate_blocked_op = { .handler = sysrq_handle_showstate_blocked, .help_msg = "show-blocked-tasks(w)", .action_msg = "Show Blocked State", .enable_mask = SYSRQ_ENABLE_DUMP, }; #ifdef CONFIG_TRACING #include <linux/ftrace.h> static void sysrq_ftrace_dump(int key) { ftrace_dump(DUMP_ALL); } static struct sysrq_key_op sysrq_ftrace_dump_op = { .handler = sysrq_ftrace_dump, .help_msg = "dump-ftrace-buffer(z)", .action_msg = "Dump ftrace buffer", .enable_mask = SYSRQ_ENABLE_DUMP, }; #else #define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL) #endif static void sysrq_handle_showmem(int key) { show_mem(0, NULL); } static struct sysrq_key_op sysrq_showmem_op = { .handler = sysrq_handle_showmem, .help_msg = "show-memory-usage(m)", .action_msg = "Show Memory", .enable_mask = SYSRQ_ENABLE_DUMP, }; /* * Signal sysrq helper function. Sends a signal to all user processes. */ static void send_sig_all(int sig) { struct task_struct *p; read_lock(&tasklist_lock); for_each_process(p) { if (p->flags & PF_KTHREAD) continue; if (is_global_init(p)) continue; do_send_sig_info(sig, SEND_SIG_PRIV, p, PIDTYPE_MAX); } read_unlock(&tasklist_lock); } static void sysrq_handle_term(int key) { send_sig_all(SIGTERM); console_loglevel = CONSOLE_LOGLEVEL_DEBUG; } static struct sysrq_key_op sysrq_term_op = { .handler = sysrq_handle_term, .help_msg = "terminate-all-tasks(e)", .action_msg = "Terminate All Tasks", .enable_mask = SYSRQ_ENABLE_SIGNAL, }; static void moom_callback(struct work_struct *ignored) { const gfp_t gfp_mask = GFP_KERNEL; struct oom_control oc = { .zonelist = node_zonelist(first_memory_node, gfp_mask), .nodemask = NULL, .memcg = NULL, .gfp_mask = gfp_mask, .order = -1, }; mutex_lock(&oom_lock); if (!out_of_memory(&oc)) pr_info("OOM request ignored. No task eligible\n"); mutex_unlock(&oom_lock); } static DECLARE_WORK(moom_work, moom_callback); static void sysrq_handle_moom(int key) { schedule_work(&moom_work); } static struct sysrq_key_op sysrq_moom_op = { .handler = sysrq_handle_moom, .help_msg = "memory-full-oom-kill(f)", .action_msg = "Manual OOM execution", .enable_mask = SYSRQ_ENABLE_SIGNAL, }; #ifdef CONFIG_BLOCK static void sysrq_handle_thaw(int key) { emergency_thaw_all(); } static struct sysrq_key_op sysrq_thaw_op = { .handler = sysrq_handle_thaw, .help_msg = "thaw-filesystems(j)", .action_msg = "Emergency Thaw of all frozen filesystems", .enable_mask = SYSRQ_ENABLE_SIGNAL, }; #endif static void sysrq_handle_kill(int key) { send_sig_all(SIGKILL); console_loglevel = CONSOLE_LOGLEVEL_DEBUG; } static struct sysrq_key_op sysrq_kill_op = { .handler = sysrq_handle_kill, .help_msg = "kill-all-tasks(i)", .action_msg = "Kill All Tasks", .enable_mask = SYSRQ_ENABLE_SIGNAL, }; static void sysrq_handle_unrt(int key) { normalize_rt_tasks(); } static struct sysrq_key_op sysrq_unrt_op = { .handler = sysrq_handle_unrt, .help_msg = "nice-all-RT-tasks(n)", .action_msg = "Nice All RT Tasks", .enable_mask = SYSRQ_ENABLE_RTNICE, }; /* Key Operations table and lock */ static DEFINE_SPINLOCK(sysrq_key_table_lock); static struct sysrq_key_op *sysrq_key_table[36] = { &sysrq_loglevel_op, /* 0 */ &sysrq_loglevel_op, /* 1 */ &sysrq_loglevel_op, /* 2 */ &sysrq_loglevel_op, /* 3 */ &sysrq_loglevel_op, /* 4 */ &sysrq_loglevel_op, /* 5 */ &sysrq_loglevel_op, /* 6 */ &sysrq_loglevel_op, /* 7 */ &sysrq_loglevel_op, /* 8 */ &sysrq_loglevel_op, /* 9 */ /* * a: Don't use for system provided sysrqs, it is handled specially on * sparc and will never arrive. */ NULL, /* a */ &sysrq_reboot_op, /* b */ &sysrq_crash_op, /* c */ &sysrq_showlocks_op, /* d */ &sysrq_term_op, /* e */ &sysrq_moom_op, /* f */ /* g: May be registered for the kernel debugger */ NULL, /* g */ NULL, /* h - reserved for help */ &sysrq_kill_op, /* i */ #ifdef CONFIG_BLOCK &sysrq_thaw_op, /* j */ #else NULL, /* j */ #endif &sysrq_SAK_op, /* k */ #ifdef CONFIG_SMP &sysrq_showallcpus_op, /* l */ #else NULL, /* l */ #endif &sysrq_showmem_op, /* m */ &sysrq_unrt_op, /* n */ /* o: This will often be registered as 'Off' at init time */ NULL, /* o */ &sysrq_showregs_op, /* p */ &sysrq_show_timers_op, /* q */ &sysrq_unraw_op, /* r */ &sysrq_sync_op, /* s */ &sysrq_showstate_op, /* t */ &sysrq_mountro_op, /* u */ /* v: May be registered for frame buffer console restore */ NULL, /* v */ &sysrq_showstate_blocked_op, /* w */ /* x: May be registered on mips for TLB dump */ /* x: May be registered on ppc/powerpc for xmon */ /* x: May be registered on sparc64 for global PMU dump */ NULL, /* x */ /* y: May be registered on sparc64 for global register dump */ NULL, /* y */ &sysrq_ftrace_dump_op, /* z */ }; /* key2index calculation, -1 on invalid index */ static int sysrq_key_table_key2index(int key) { int retval; if ((key >= '0') && (key <= '9')) retval = key - '0'; else if ((key >= 'a') && (key <= 'z')) retval = key + 10 - 'a'; else retval = -1; return retval; } /* * get and put functions for the table, exposed to modules. */ struct sysrq_key_op *__sysrq_get_key_op(int key) { struct sysrq_key_op *op_p = NULL; int i; i = sysrq_key_table_key2index(key); if (i != -1) op_p = sysrq_key_table[i]; return op_p; } static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p) { int i = sysrq_key_table_key2index(key); if (i != -1) sysrq_key_table[i] = op_p; } void __handle_sysrq(int key, bool check_mask) { struct sysrq_key_op *op_p; int orig_log_level; int orig_suppress_printk; int i; orig_suppress_printk = suppress_printk; suppress_printk = 0; rcu_sysrq_start(); rcu_read_lock(); /* * Raise the apparent loglevel to maximum so that the sysrq header * is shown to provide the user with positive feedback. We do not * simply emit this at KERN_EMERG as that would change message * routing in the consumers of /proc/kmsg. */ orig_log_level = console_loglevel; console_loglevel = CONSOLE_LOGLEVEL_DEFAULT; op_p = __sysrq_get_key_op(key); if (op_p) { /* * Should we check for enabled operations (/proc/sysrq-trigger * should not) and is the invoked operation enabled? */ if (!check_mask || sysrq_on_mask(op_p->enable_mask)) { pr_info("%s\n", op_p->action_msg); console_loglevel = orig_log_level; op_p->handler(key); } else { pr_info("This sysrq operation is disabled.\n"); console_loglevel = orig_log_level; } } else { pr_info("HELP : "); /* Only print the help msg once per handler */ for (i = 0; i < ARRAY_SIZE(sysrq_key_table); i++) { if (sysrq_key_table[i]) { int j; for (j = 0; sysrq_key_table[i] != sysrq_key_table[j]; j++) ; if (j != i) continue; pr_cont("%s ", sysrq_key_table[i]->help_msg); } } pr_cont("\n"); console_loglevel = orig_log_level; } rcu_read_unlock(); rcu_sysrq_end(); suppress_printk = orig_suppress_printk; } void handle_sysrq(int key) { if (sysrq_on()) __handle_sysrq(key, true); } EXPORT_SYMBOL(handle_sysrq); #ifdef CONFIG_INPUT static int sysrq_reset_downtime_ms; /* Simple translation table for the SysRq keys */ static const unsigned char sysrq_xlate[KEY_CNT] = "\000\0331234567890-=\177\t" /* 0x00 - 0x0f */ "qwertyuiop[]\r\000as" /* 0x10 - 0x1f */ "dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */ "bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */ "\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */ "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */ "\r\000/"; /* 0x60 - 0x6f */ struct sysrq_state { struct input_handle handle; struct work_struct reinject_work; unsigned long key_down[BITS_TO_LONGS(KEY_CNT)]; unsigned int alt; unsigned int alt_use; bool active; bool need_reinject; bool reinjecting; /* reset sequence handling */ bool reset_canceled; bool reset_requested; unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)]; int reset_seq_len; int reset_seq_cnt; int reset_seq_version; struct timer_list keyreset_timer; }; #define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */ static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX]; static unsigned int sysrq_reset_seq_len; static unsigned int sysrq_reset_seq_version = 1; static void sysrq_parse_reset_sequence(struct sysrq_state *state) { int i; unsigned short key; state->reset_seq_cnt = 0; for (i = 0; i < sysrq_reset_seq_len; i++) { key = sysrq_reset_seq[i]; if (key == KEY_RESERVED || key > KEY_MAX) break; __set_bit(key, state->reset_keybit); state->reset_seq_len++; if (test_bit(key, state->key_down)) state->reset_seq_cnt++; } /* Disable reset until old keys are not released */ state->reset_canceled = state->reset_seq_cnt != 0; state->reset_seq_version = sysrq_reset_seq_version; } static void sysrq_do_reset(struct timer_list *t) { struct sysrq_state *state = from_timer(state, t, keyreset_timer); state->reset_requested = true; orderly_reboot(); } static void sysrq_handle_reset_request(struct sysrq_state *state) { if (state->reset_requested) __handle_sysrq(sysrq_xlate[KEY_B], false); if (sysrq_reset_downtime_ms) mod_timer(&state->keyreset_timer, jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms)); else sysrq_do_reset(&state->keyreset_timer); } static void sysrq_detect_reset_sequence(struct sysrq_state *state, unsigned int code, int value) { if (!test_bit(code, state->reset_keybit)) { /* * Pressing any key _not_ in reset sequence cancels * the reset sequence. Also cancelling the timer in * case additional keys were pressed after a reset * has been requested. */ if (value && state->reset_seq_cnt) { state->reset_canceled = true; del_timer(&state->keyreset_timer); } } else if (value == 0) { /* * Key release - all keys in the reset sequence need * to be pressed and held for the reset timeout * to hold. */ del_timer(&state->keyreset_timer); if (--state->reset_seq_cnt == 0) state->reset_canceled = false; } else if (value == 1) { /* key press, not autorepeat */ if (++state->reset_seq_cnt == state->reset_seq_len && !state->reset_canceled) { sysrq_handle_reset_request(state); } } } #ifdef CONFIG_OF static void sysrq_of_get_keyreset_config(void) { u32 key; struct device_node *np; struct property *prop; const __be32 *p; np = of_find_node_by_path("/chosen/linux,sysrq-reset-seq"); if (!np) { pr_debug("No sysrq node found"); return; } /* Reset in case a __weak definition was present */ sysrq_reset_seq_len = 0; of_property_for_each_u32(np, "keyset", prop, p, key) { if (key == KEY_RESERVED || key > KEY_MAX || sysrq_reset_seq_len == SYSRQ_KEY_RESET_MAX) break; sysrq_reset_seq[sysrq_reset_seq_len++] = (unsigned short)key; } /* Get reset timeout if any. */ of_property_read_u32(np, "timeout-ms", &sysrq_reset_downtime_ms); of_node_put(np); } #else static void sysrq_of_get_keyreset_config(void) { } #endif static void sysrq_reinject_alt_sysrq(struct work_struct *work) { struct sysrq_state *sysrq = container_of(work, struct sysrq_state, reinject_work); struct input_handle *handle = &sysrq->handle; unsigned int alt_code = sysrq->alt_use; if (sysrq->need_reinject) { /* we do not want the assignment to be reordered */ sysrq->reinjecting = true; mb(); /* Simulate press and release of Alt + SysRq */ input_inject_event(handle, EV_KEY, alt_code, 1); input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1); input_inject_event(handle, EV_SYN, SYN_REPORT, 1); input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0); input_inject_event(handle, EV_KEY, alt_code, 0); input_inject_event(handle, EV_SYN, SYN_REPORT, 1); mb(); sysrq->reinjecting = false; } } static bool sysrq_handle_keypress(struct sysrq_state *sysrq, unsigned int code, int value) { bool was_active = sysrq->active; bool suppress; switch (code) { case KEY_LEFTALT: case KEY_RIGHTALT: if (!value) { /* One of ALTs is being released */ if (sysrq->active && code == sysrq->alt_use) sysrq->active = false; sysrq->alt = KEY_RESERVED; } else if (value != 2) { sysrq->alt = code; sysrq->need_reinject = false; } break; case KEY_SYSRQ: if (value == 1 && sysrq->alt != KEY_RESERVED) { sysrq->active = true; sysrq->alt_use = sysrq->alt; /* * If nothing else will be pressed we'll need * to re-inject Alt-SysRq keysroke. */ sysrq->need_reinject = true; } /* * Pretend that sysrq was never pressed at all. This * is needed to properly handle KGDB which will try * to release all keys after exiting debugger. If we * do not clear key bit it KGDB will end up sending * release events for Alt and SysRq, potentially * triggering print screen function. */ if (sysrq->active) clear_bit(KEY_SYSRQ, sysrq->handle.dev->key); break; default: if (sysrq->active && value && value != 2) { sysrq->need_reinject = false; __handle_sysrq(sysrq_xlate[code], true); } break; } suppress = sysrq->active; if (!sysrq->active) { /* * See if reset sequence has changed since the last time. */ if (sysrq->reset_seq_version != sysrq_reset_seq_version) sysrq_parse_reset_sequence(sysrq); /* * If we are not suppressing key presses keep track of * keyboard state so we can release keys that have been * pressed before entering SysRq mode. */ if (value) set_bit(code, sysrq->key_down); else clear_bit(code, sysrq->key_down); if (was_active) schedule_work(&sysrq->reinject_work); /* Check for reset sequence */ sysrq_detect_reset_sequence(sysrq, code, value); } else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) { /* * Pass on release events for keys that was pressed before * entering SysRq mode. */ suppress = false; } return suppress; } static bool sysrq_filter(struct input_handle *handle, unsigned int type, unsigned int code, int value) { struct sysrq_state *sysrq = handle->private; bool suppress; /* * Do not filter anything if we are in the process of re-injecting * Alt+SysRq combination. */ if (sysrq->reinjecting) return false; switch (type) { case EV_SYN: suppress = false; break; case EV_KEY: suppress = sysrq_handle_keypress(sysrq, code, value); break; default: suppress = sysrq->active; break; } return suppress; } static int sysrq_connect(struct input_handler *handler, struct input_dev *dev, const struct input_device_id *id) { struct sysrq_state *sysrq; int error; sysrq = kzalloc(sizeof(struct sysrq_state), GFP_KERNEL); if (!sysrq) return -ENOMEM; INIT_WORK(&sysrq->reinject_work, sysrq_reinject_alt_sysrq); sysrq->handle.dev = dev; sysrq->handle.handler = handler; sysrq->handle.name = "sysrq"; sysrq->handle.private = sysrq; timer_setup(&sysrq->keyreset_timer, sysrq_do_reset, 0); error = input_register_handle(&sysrq->handle); if (error) { pr_err("Failed to register input sysrq handler, error %d\n", error); goto err_free; } error = input_open_device(&sysrq->handle); if (error) { pr_err("Failed to open input device, error %d\n", error); goto err_unregister; } return 0; err_unregister: input_unregister_handle(&sysrq->handle); err_free: kfree(sysrq); return error; } static void sysrq_disconnect(struct input_handle *handle) { struct sysrq_state *sysrq = handle->private; input_close_device(handle); cancel_work_sync(&sysrq->reinject_work); del_timer_sync(&sysrq->keyreset_timer); input_unregister_handle(handle); kfree(sysrq); } /* * We are matching on KEY_LEFTALT instead of KEY_SYSRQ because not all * keyboards have SysRq key predefined and so user may add it to keymap * later, but we expect all such keyboards to have left alt. */ static const struct input_device_id sysrq_ids[] = { { .flags = INPUT_DEVICE_ID_MATCH_EVBIT | INPUT_DEVICE_ID_MATCH_KEYBIT, .evbit = { [BIT_WORD(EV_KEY)] = BIT_MASK(EV_KEY) }, .keybit = { [BIT_WORD(KEY_LEFTALT)] = BIT_MASK(KEY_LEFTALT) }, }, { }, }; static struct input_handler sysrq_handler = { .filter = sysrq_filter, .connect = sysrq_connect, .disconnect = sysrq_disconnect, .name = "sysrq", .id_table = sysrq_ids, }; static bool sysrq_handler_registered; static inline void sysrq_register_handler(void) { int error; sysrq_of_get_keyreset_config(); error = input_register_handler(&sysrq_handler); if (error) pr_err("Failed to register input handler, error %d", error); else sysrq_handler_registered = true; } static inline void sysrq_unregister_handler(void) { if (sysrq_handler_registered) { input_unregister_handler(&sysrq_handler); sysrq_handler_registered = false; } } static int sysrq_reset_seq_param_set(const char *buffer, const struct kernel_param *kp) { unsigned long val; int error; error = kstrtoul(buffer, 0, &val); if (error < 0) return error; if (val > KEY_MAX) return -EINVAL; *((unsigned short *)kp->arg) = val; sysrq_reset_seq_version++; return 0; } static const struct kernel_param_ops param_ops_sysrq_reset_seq = { .get = param_get_ushort, .set = sysrq_reset_seq_param_set, }; #define param_check_sysrq_reset_seq(name, p) \ __param_check(name, p, unsigned short) /* * not really modular, but the easiest way to keep compat with existing * bootargs behaviour is to continue using module_param here. */ module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq, &sysrq_reset_seq_len, 0644); module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644); #else static inline void sysrq_register_handler(void) { } static inline void sysrq_unregister_handler(void) { } #endif /* CONFIG_INPUT */ int sysrq_toggle_support(int enable_mask) { bool was_enabled = sysrq_on(); sysrq_enabled = enable_mask; if (was_enabled != sysrq_on()) { if (sysrq_on()) sysrq_register_handler(); else sysrq_unregister_handler(); } return 0; } static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p, struct sysrq_key_op *remove_op_p) { int retval; spin_lock(&sysrq_key_table_lock); if (__sysrq_get_key_op(key) == remove_op_p) { __sysrq_put_key_op(key, insert_op_p); retval = 0; } else { retval = -1; } spin_unlock(&sysrq_key_table_lock); /* * A concurrent __handle_sysrq either got the old op or the new op. * Wait for it to go away before returning, so the code for an old * op is not freed (eg. on module unload) while it is in use. */ synchronize_rcu(); return retval; } int register_sysrq_key(int key, struct sysrq_key_op *op_p) { return __sysrq_swap_key_ops(key, op_p, NULL); } EXPORT_SYMBOL(register_sysrq_key); int unregister_sysrq_key(int key, struct sysrq_key_op *op_p) { return __sysrq_swap_key_ops(key, NULL, op_p); } EXPORT_SYMBOL(unregister_sysrq_key); #ifdef CONFIG_PROC_FS /* * writing 'C' to /proc/sysrq-trigger is like sysrq-C */ static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { if (count) { char c; if (get_user(c, buf)) return -EFAULT; __handle_sysrq(c, false); } return count; } static const struct file_operations proc_sysrq_trigger_operations = { .write = write_sysrq_trigger, .llseek = noop_llseek, }; static void sysrq_init_procfs(void) { if (!proc_create("sysrq-trigger", S_IWUSR, NULL, &proc_sysrq_trigger_operations)) pr_err("Failed to register proc interface\n"); } #else static inline void sysrq_init_procfs(void) { } #endif /* CONFIG_PROC_FS */ static int __init sysrq_init(void) { sysrq_init_procfs(); if (sysrq_on()) sysrq_register_handler(); return 0; } device_initcall(sysrq_init);