/* * Linux Magic System Request Key Hacks * * (c) 1997 Martin Mares * based on ideas by Pavel Machek * * (c) 2000 Crutcher Dunnavant * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* for fsync_bdev() */ #include #include #include #include #include #include #include #include #include #include /* Whether we react on sysrq keys or just ignore them */ static int __read_mostly sysrq_enabled = 1; 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 = 7; printk("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", .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) { struct kbd_struct *kbd = &kbd_table[fg_console]; if (kbd) kbd->kbdmode = default_utf8 ? VC_UNICODE : VC_XLATE; } static struct sysrq_key_op sysrq_unraw_op = { .handler = sysrq_handle_unraw, .help_msg = "unRaw", .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) { char *killer = NULL; panic_on_oops = 1; /* force panic */ wmb(); *killer = 1; } static struct sysrq_key_op sysrq_crash_op = { .handler = sysrq_handle_crash, .help_msg = "Crash", .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", .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", .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", .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_SPINLOCK(show_lock); static void showacpu(void *dummy) { unsigned long flags; /* Idle CPUs have no interesting backtrace. */ if (idle_cpu(smp_processor_id())) return; spin_lock_irqsave(&show_lock, flags); printk(KERN_INFO "CPU%d:\n", smp_processor_id()); show_stack(NULL, NULL); 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 = get_irq_regs(); if (regs) { printk(KERN_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 = 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(); } 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 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(); } 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; for_each_process(p) { if (p->mm && !is_global_init(p)) /* Not swapper, init nor kernel thread */ force_sig(sig, p); } } static void sysrq_handle_term(int key) { send_sig_all(SIGTERM); console_loglevel = 8; } 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) { out_of_memory(node_zonelist(0, GFP_KERNEL), GFP_KERNEL, 0, NULL); } 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 = 8; } 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 */ NULL, /* b */ NULL, /* c & ibm_emac driver debug */ &sysrq_showlocks_op, /* d */ NULL, /* e */ NULL, /* f */ /* g: May be registered for the kernel debugger */ NULL, /* g */ NULL, /* h - reserved for help */ NULL, /* i */ NULL, /* j */ &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 */ NULL, /* u */ /* v: May be registered for frame buffer console restore */ NULL, /* v */ &sysrq_showstate_blocked_op, /* w */ /* x: May be registered on ppc/powerpc for xmon */ 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 i; unsigned long flags; spin_lock_irqsave(&sysrq_key_table_lock, flags); /* * 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 = 7; printk(KERN_INFO "SysRq : "); 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)) { printk("%s\n", op_p->action_msg); console_loglevel = orig_log_level; op_p->handler(key); } else { printk("This sysrq operation is disabled.\n"); } } else { printk("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; printk("%s ", sysrq_key_table[i]->help_msg); } } printk("\n"); console_loglevel = orig_log_level; } spin_unlock_irqrestore(&sysrq_key_table_lock, flags); } void handle_sysrq(int key) { if (sysrq_on()) __handle_sysrq(key, true); } EXPORT_SYMBOL(handle_sysrq); #ifdef CONFIG_INPUT /* Simple translation table for the SysRq keys */ static const unsigned char sysrq_xlate[KEY_MAX + 1] = "\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 */ static bool sysrq_down; static int sysrq_alt_use; static int sysrq_alt; static bool sysrq_filter(struct input_handle *handle, unsigned int type, unsigned int code, int value) { if (type != EV_KEY) goto out; switch (code) { case KEY_LEFTALT: case KEY_RIGHTALT: if (value) sysrq_alt = code; else { if (sysrq_down && code == sysrq_alt_use) sysrq_down = false; sysrq_alt = 0; } break; case KEY_SYSRQ: if (value == 1 && sysrq_alt) { sysrq_down = true; sysrq_alt_use = sysrq_alt; } break; default: if (sysrq_down && value && value != 2) __handle_sysrq(sysrq_xlate[code], true); break; } out: return sysrq_down; } static int sysrq_connect(struct input_handler *handler, struct input_dev *dev, const struct input_device_id *id) { struct input_handle *handle; int error; sysrq_down = false; sysrq_alt = 0; handle = kzalloc(sizeof(struct input_handle), GFP_KERNEL); if (!handle) return -ENOMEM; handle->dev = dev; handle->handler = handler; handle->name = "sysrq"; error = input_register_handle(handle); if (error) { pr_err("Failed to register input sysrq handler, error %d\n", error); goto err_free; } error = input_open_device(handle); if (error) { pr_err("Failed to open input device, error %d\n", error); goto err_unregister; } return 0; err_unregister: input_unregister_handle(handle); err_free: kfree(handle); return error; } static void sysrq_disconnect(struct input_handle *handle) { input_close_device(handle); input_unregister_handle(handle); kfree(handle); } /* * We are matching on KEY_LEFTALT insteard of KEY_SYSRQ because not all * keyboards have SysRq ikey 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_MASK(EV_KEY) }, .keybit = { 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; 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; } } #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; unsigned long flags; spin_lock_irqsave(&sysrq_key_table_lock, flags); if (__sysrq_get_key_op(key) == remove_op_p) { __sysrq_put_key_op(key, insert_op_p); retval = 0; } else { retval = -1; } spin_unlock_irqrestore(&sysrq_key_table_lock, flags); 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, }; 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; } module_init(sysrq_init);