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-rw-r--r--kernel/reboot.c1312
1 files changed, 1312 insertions, 0 deletions
diff --git a/kernel/reboot.c b/kernel/reboot.c
new file mode 100644
index 0000000000..6ebef11c88
--- /dev/null
+++ b/kernel/reboot.c
@@ -0,0 +1,1312 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/kernel/reboot.c
+ *
+ * Copyright (C) 2013 Linus Torvalds
+ */
+
+#define pr_fmt(fmt) "reboot: " fmt
+
+#include <linux/atomic.h>
+#include <linux/ctype.h>
+#include <linux/export.h>
+#include <linux/kexec.h>
+#include <linux/kmod.h>
+#include <linux/kmsg_dump.h>
+#include <linux/reboot.h>
+#include <linux/suspend.h>
+#include <linux/syscalls.h>
+#include <linux/syscore_ops.h>
+#include <linux/uaccess.h>
+
+/*
+ * this indicates whether you can reboot with ctrl-alt-del: the default is yes
+ */
+
+static int C_A_D = 1;
+struct pid *cad_pid;
+EXPORT_SYMBOL(cad_pid);
+
+#if defined(CONFIG_ARM)
+#define DEFAULT_REBOOT_MODE = REBOOT_HARD
+#else
+#define DEFAULT_REBOOT_MODE
+#endif
+enum reboot_mode reboot_mode DEFAULT_REBOOT_MODE;
+EXPORT_SYMBOL_GPL(reboot_mode);
+enum reboot_mode panic_reboot_mode = REBOOT_UNDEFINED;
+
+/*
+ * This variable is used privately to keep track of whether or not
+ * reboot_type is still set to its default value (i.e., reboot= hasn't
+ * been set on the command line). This is needed so that we can
+ * suppress DMI scanning for reboot quirks. Without it, it's
+ * impossible to override a faulty reboot quirk without recompiling.
+ */
+int reboot_default = 1;
+int reboot_cpu;
+enum reboot_type reboot_type = BOOT_ACPI;
+int reboot_force;
+
+struct sys_off_handler {
+ struct notifier_block nb;
+ int (*sys_off_cb)(struct sys_off_data *data);
+ void *cb_data;
+ enum sys_off_mode mode;
+ bool blocking;
+ void *list;
+};
+
+/*
+ * Temporary stub that prevents linkage failure while we're in process
+ * of removing all uses of legacy pm_power_off() around the kernel.
+ */
+void __weak (*pm_power_off)(void);
+
+/**
+ * emergency_restart - reboot the system
+ *
+ * Without shutting down any hardware or taking any locks
+ * reboot the system. This is called when we know we are in
+ * trouble so this is our best effort to reboot. This is
+ * safe to call in interrupt context.
+ */
+void emergency_restart(void)
+{
+ kmsg_dump(KMSG_DUMP_EMERG);
+ system_state = SYSTEM_RESTART;
+ machine_emergency_restart();
+}
+EXPORT_SYMBOL_GPL(emergency_restart);
+
+void kernel_restart_prepare(char *cmd)
+{
+ blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
+ system_state = SYSTEM_RESTART;
+ usermodehelper_disable();
+ device_shutdown();
+}
+
+/**
+ * register_reboot_notifier - Register function to be called at reboot time
+ * @nb: Info about notifier function to be called
+ *
+ * Registers a function with the list of functions
+ * to be called at reboot time.
+ *
+ * Currently always returns zero, as blocking_notifier_chain_register()
+ * always returns zero.
+ */
+int register_reboot_notifier(struct notifier_block *nb)
+{
+ return blocking_notifier_chain_register(&reboot_notifier_list, nb);
+}
+EXPORT_SYMBOL(register_reboot_notifier);
+
+/**
+ * unregister_reboot_notifier - Unregister previously registered reboot notifier
+ * @nb: Hook to be unregistered
+ *
+ * Unregisters a previously registered reboot
+ * notifier function.
+ *
+ * Returns zero on success, or %-ENOENT on failure.
+ */
+int unregister_reboot_notifier(struct notifier_block *nb)
+{
+ return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
+}
+EXPORT_SYMBOL(unregister_reboot_notifier);
+
+static void devm_unregister_reboot_notifier(struct device *dev, void *res)
+{
+ WARN_ON(unregister_reboot_notifier(*(struct notifier_block **)res));
+}
+
+int devm_register_reboot_notifier(struct device *dev, struct notifier_block *nb)
+{
+ struct notifier_block **rcnb;
+ int ret;
+
+ rcnb = devres_alloc(devm_unregister_reboot_notifier,
+ sizeof(*rcnb), GFP_KERNEL);
+ if (!rcnb)
+ return -ENOMEM;
+
+ ret = register_reboot_notifier(nb);
+ if (!ret) {
+ *rcnb = nb;
+ devres_add(dev, rcnb);
+ } else {
+ devres_free(rcnb);
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL(devm_register_reboot_notifier);
+
+/*
+ * Notifier list for kernel code which wants to be called
+ * to restart the system.
+ */
+static ATOMIC_NOTIFIER_HEAD(restart_handler_list);
+
+/**
+ * register_restart_handler - Register function to be called to reset
+ * the system
+ * @nb: Info about handler function to be called
+ * @nb->priority: Handler priority. Handlers should follow the
+ * following guidelines for setting priorities.
+ * 0: Restart handler of last resort,
+ * with limited restart capabilities
+ * 128: Default restart handler; use if no other
+ * restart handler is expected to be available,
+ * and/or if restart functionality is
+ * sufficient to restart the entire system
+ * 255: Highest priority restart handler, will
+ * preempt all other restart handlers
+ *
+ * Registers a function with code to be called to restart the
+ * system.
+ *
+ * Registered functions will be called from machine_restart as last
+ * step of the restart sequence (if the architecture specific
+ * machine_restart function calls do_kernel_restart - see below
+ * for details).
+ * Registered functions are expected to restart the system immediately.
+ * If more than one function is registered, the restart handler priority
+ * selects which function will be called first.
+ *
+ * Restart handlers are expected to be registered from non-architecture
+ * code, typically from drivers. A typical use case would be a system
+ * where restart functionality is provided through a watchdog. Multiple
+ * restart handlers may exist; for example, one restart handler might
+ * restart the entire system, while another only restarts the CPU.
+ * In such cases, the restart handler which only restarts part of the
+ * hardware is expected to register with low priority to ensure that
+ * it only runs if no other means to restart the system is available.
+ *
+ * Currently always returns zero, as atomic_notifier_chain_register()
+ * always returns zero.
+ */
+int register_restart_handler(struct notifier_block *nb)
+{
+ return atomic_notifier_chain_register(&restart_handler_list, nb);
+}
+EXPORT_SYMBOL(register_restart_handler);
+
+/**
+ * unregister_restart_handler - Unregister previously registered
+ * restart handler
+ * @nb: Hook to be unregistered
+ *
+ * Unregisters a previously registered restart handler function.
+ *
+ * Returns zero on success, or %-ENOENT on failure.
+ */
+int unregister_restart_handler(struct notifier_block *nb)
+{
+ return atomic_notifier_chain_unregister(&restart_handler_list, nb);
+}
+EXPORT_SYMBOL(unregister_restart_handler);
+
+/**
+ * do_kernel_restart - Execute kernel restart handler call chain
+ *
+ * Calls functions registered with register_restart_handler.
+ *
+ * Expected to be called from machine_restart as last step of the restart
+ * sequence.
+ *
+ * Restarts the system immediately if a restart handler function has been
+ * registered. Otherwise does nothing.
+ */
+void do_kernel_restart(char *cmd)
+{
+ atomic_notifier_call_chain(&restart_handler_list, reboot_mode, cmd);
+}
+
+void migrate_to_reboot_cpu(void)
+{
+ /* The boot cpu is always logical cpu 0 */
+ int cpu = reboot_cpu;
+
+ cpu_hotplug_disable();
+
+ /* Make certain the cpu I'm about to reboot on is online */
+ if (!cpu_online(cpu))
+ cpu = cpumask_first(cpu_online_mask);
+
+ /* Prevent races with other tasks migrating this task */
+ current->flags |= PF_NO_SETAFFINITY;
+
+ /* Make certain I only run on the appropriate processor */
+ set_cpus_allowed_ptr(current, cpumask_of(cpu));
+}
+
+/*
+ * Notifier list for kernel code which wants to be called
+ * to prepare system for restart.
+ */
+static BLOCKING_NOTIFIER_HEAD(restart_prep_handler_list);
+
+static void do_kernel_restart_prepare(void)
+{
+ blocking_notifier_call_chain(&restart_prep_handler_list, 0, NULL);
+}
+
+/**
+ * kernel_restart - reboot the system
+ * @cmd: pointer to buffer containing command to execute for restart
+ * or %NULL
+ *
+ * Shutdown everything and perform a clean reboot.
+ * This is not safe to call in interrupt context.
+ */
+void kernel_restart(char *cmd)
+{
+ kernel_restart_prepare(cmd);
+ do_kernel_restart_prepare();
+ migrate_to_reboot_cpu();
+ syscore_shutdown();
+ if (!cmd)
+ pr_emerg("Restarting system\n");
+ else
+ pr_emerg("Restarting system with command '%s'\n", cmd);
+ kmsg_dump(KMSG_DUMP_SHUTDOWN);
+ machine_restart(cmd);
+}
+EXPORT_SYMBOL_GPL(kernel_restart);
+
+static void kernel_shutdown_prepare(enum system_states state)
+{
+ blocking_notifier_call_chain(&reboot_notifier_list,
+ (state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL);
+ system_state = state;
+ usermodehelper_disable();
+ device_shutdown();
+}
+/**
+ * kernel_halt - halt the system
+ *
+ * Shutdown everything and perform a clean system halt.
+ */
+void kernel_halt(void)
+{
+ kernel_shutdown_prepare(SYSTEM_HALT);
+ migrate_to_reboot_cpu();
+ syscore_shutdown();
+ pr_emerg("System halted\n");
+ kmsg_dump(KMSG_DUMP_SHUTDOWN);
+ machine_halt();
+}
+EXPORT_SYMBOL_GPL(kernel_halt);
+
+/*
+ * Notifier list for kernel code which wants to be called
+ * to prepare system for power off.
+ */
+static BLOCKING_NOTIFIER_HEAD(power_off_prep_handler_list);
+
+/*
+ * Notifier list for kernel code which wants to be called
+ * to power off system.
+ */
+static ATOMIC_NOTIFIER_HEAD(power_off_handler_list);
+
+static int sys_off_notify(struct notifier_block *nb,
+ unsigned long mode, void *cmd)
+{
+ struct sys_off_handler *handler;
+ struct sys_off_data data = {};
+
+ handler = container_of(nb, struct sys_off_handler, nb);
+ data.cb_data = handler->cb_data;
+ data.mode = mode;
+ data.cmd = cmd;
+
+ return handler->sys_off_cb(&data);
+}
+
+static struct sys_off_handler platform_sys_off_handler;
+
+static struct sys_off_handler *alloc_sys_off_handler(int priority)
+{
+ struct sys_off_handler *handler;
+ gfp_t flags;
+
+ /*
+ * Platforms like m68k can't allocate sys_off handler dynamically
+ * at the early boot time because memory allocator isn't available yet.
+ */
+ if (priority == SYS_OFF_PRIO_PLATFORM) {
+ handler = &platform_sys_off_handler;
+ if (handler->cb_data)
+ return ERR_PTR(-EBUSY);
+ } else {
+ if (system_state > SYSTEM_RUNNING)
+ flags = GFP_ATOMIC;
+ else
+ flags = GFP_KERNEL;
+
+ handler = kzalloc(sizeof(*handler), flags);
+ if (!handler)
+ return ERR_PTR(-ENOMEM);
+ }
+
+ return handler;
+}
+
+static void free_sys_off_handler(struct sys_off_handler *handler)
+{
+ if (handler == &platform_sys_off_handler)
+ memset(handler, 0, sizeof(*handler));
+ else
+ kfree(handler);
+}
+
+/**
+ * register_sys_off_handler - Register sys-off handler
+ * @mode: Sys-off mode
+ * @priority: Handler priority
+ * @callback: Callback function
+ * @cb_data: Callback argument
+ *
+ * Registers system power-off or restart handler that will be invoked
+ * at the step corresponding to the given sys-off mode. Handler's callback
+ * should return NOTIFY_DONE to permit execution of the next handler in
+ * the call chain or NOTIFY_STOP to break the chain (in error case for
+ * example).
+ *
+ * Multiple handlers can be registered at the default priority level.
+ *
+ * Only one handler can be registered at the non-default priority level,
+ * otherwise ERR_PTR(-EBUSY) is returned.
+ *
+ * Returns a new instance of struct sys_off_handler on success, or
+ * an ERR_PTR()-encoded error code otherwise.
+ */
+struct sys_off_handler *
+register_sys_off_handler(enum sys_off_mode mode,
+ int priority,
+ int (*callback)(struct sys_off_data *data),
+ void *cb_data)
+{
+ struct sys_off_handler *handler;
+ int err;
+
+ handler = alloc_sys_off_handler(priority);
+ if (IS_ERR(handler))
+ return handler;
+
+ switch (mode) {
+ case SYS_OFF_MODE_POWER_OFF_PREPARE:
+ handler->list = &power_off_prep_handler_list;
+ handler->blocking = true;
+ break;
+
+ case SYS_OFF_MODE_POWER_OFF:
+ handler->list = &power_off_handler_list;
+ break;
+
+ case SYS_OFF_MODE_RESTART_PREPARE:
+ handler->list = &restart_prep_handler_list;
+ handler->blocking = true;
+ break;
+
+ case SYS_OFF_MODE_RESTART:
+ handler->list = &restart_handler_list;
+ break;
+
+ default:
+ free_sys_off_handler(handler);
+ return ERR_PTR(-EINVAL);
+ }
+
+ handler->nb.notifier_call = sys_off_notify;
+ handler->nb.priority = priority;
+ handler->sys_off_cb = callback;
+ handler->cb_data = cb_data;
+ handler->mode = mode;
+
+ if (handler->blocking) {
+ if (priority == SYS_OFF_PRIO_DEFAULT)
+ err = blocking_notifier_chain_register(handler->list,
+ &handler->nb);
+ else
+ err = blocking_notifier_chain_register_unique_prio(handler->list,
+ &handler->nb);
+ } else {
+ if (priority == SYS_OFF_PRIO_DEFAULT)
+ err = atomic_notifier_chain_register(handler->list,
+ &handler->nb);
+ else
+ err = atomic_notifier_chain_register_unique_prio(handler->list,
+ &handler->nb);
+ }
+
+ if (err) {
+ free_sys_off_handler(handler);
+ return ERR_PTR(err);
+ }
+
+ return handler;
+}
+EXPORT_SYMBOL_GPL(register_sys_off_handler);
+
+/**
+ * unregister_sys_off_handler - Unregister sys-off handler
+ * @handler: Sys-off handler
+ *
+ * Unregisters given sys-off handler.
+ */
+void unregister_sys_off_handler(struct sys_off_handler *handler)
+{
+ int err;
+
+ if (IS_ERR_OR_NULL(handler))
+ return;
+
+ if (handler->blocking)
+ err = blocking_notifier_chain_unregister(handler->list,
+ &handler->nb);
+ else
+ err = atomic_notifier_chain_unregister(handler->list,
+ &handler->nb);
+
+ /* sanity check, shall never happen */
+ WARN_ON(err);
+
+ free_sys_off_handler(handler);
+}
+EXPORT_SYMBOL_GPL(unregister_sys_off_handler);
+
+static void devm_unregister_sys_off_handler(void *data)
+{
+ struct sys_off_handler *handler = data;
+
+ unregister_sys_off_handler(handler);
+}
+
+/**
+ * devm_register_sys_off_handler - Register sys-off handler
+ * @dev: Device that registers handler
+ * @mode: Sys-off mode
+ * @priority: Handler priority
+ * @callback: Callback function
+ * @cb_data: Callback argument
+ *
+ * Registers resource-managed sys-off handler.
+ *
+ * Returns zero on success, or error code on failure.
+ */
+int devm_register_sys_off_handler(struct device *dev,
+ enum sys_off_mode mode,
+ int priority,
+ int (*callback)(struct sys_off_data *data),
+ void *cb_data)
+{
+ struct sys_off_handler *handler;
+
+ handler = register_sys_off_handler(mode, priority, callback, cb_data);
+ if (IS_ERR(handler))
+ return PTR_ERR(handler);
+
+ return devm_add_action_or_reset(dev, devm_unregister_sys_off_handler,
+ handler);
+}
+EXPORT_SYMBOL_GPL(devm_register_sys_off_handler);
+
+/**
+ * devm_register_power_off_handler - Register power-off handler
+ * @dev: Device that registers callback
+ * @callback: Callback function
+ * @cb_data: Callback's argument
+ *
+ * Registers resource-managed sys-off handler with a default priority
+ * and using power-off mode.
+ *
+ * Returns zero on success, or error code on failure.
+ */
+int devm_register_power_off_handler(struct device *dev,
+ int (*callback)(struct sys_off_data *data),
+ void *cb_data)
+{
+ return devm_register_sys_off_handler(dev,
+ SYS_OFF_MODE_POWER_OFF,
+ SYS_OFF_PRIO_DEFAULT,
+ callback, cb_data);
+}
+EXPORT_SYMBOL_GPL(devm_register_power_off_handler);
+
+/**
+ * devm_register_restart_handler - Register restart handler
+ * @dev: Device that registers callback
+ * @callback: Callback function
+ * @cb_data: Callback's argument
+ *
+ * Registers resource-managed sys-off handler with a default priority
+ * and using restart mode.
+ *
+ * Returns zero on success, or error code on failure.
+ */
+int devm_register_restart_handler(struct device *dev,
+ int (*callback)(struct sys_off_data *data),
+ void *cb_data)
+{
+ return devm_register_sys_off_handler(dev,
+ SYS_OFF_MODE_RESTART,
+ SYS_OFF_PRIO_DEFAULT,
+ callback, cb_data);
+}
+EXPORT_SYMBOL_GPL(devm_register_restart_handler);
+
+static struct sys_off_handler *platform_power_off_handler;
+
+static int platform_power_off_notify(struct sys_off_data *data)
+{
+ void (*platform_power_power_off_cb)(void) = data->cb_data;
+
+ platform_power_power_off_cb();
+
+ return NOTIFY_DONE;
+}
+
+/**
+ * register_platform_power_off - Register platform-level power-off callback
+ * @power_off: Power-off callback
+ *
+ * Registers power-off callback that will be called as last step
+ * of the power-off sequence. This callback is expected to be invoked
+ * for the last resort. Only one platform power-off callback is allowed
+ * to be registered at a time.
+ *
+ * Returns zero on success, or error code on failure.
+ */
+int register_platform_power_off(void (*power_off)(void))
+{
+ struct sys_off_handler *handler;
+
+ handler = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF,
+ SYS_OFF_PRIO_PLATFORM,
+ platform_power_off_notify,
+ power_off);
+ if (IS_ERR(handler))
+ return PTR_ERR(handler);
+
+ platform_power_off_handler = handler;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(register_platform_power_off);
+
+/**
+ * unregister_platform_power_off - Unregister platform-level power-off callback
+ * @power_off: Power-off callback
+ *
+ * Unregisters previously registered platform power-off callback.
+ */
+void unregister_platform_power_off(void (*power_off)(void))
+{
+ if (platform_power_off_handler &&
+ platform_power_off_handler->cb_data == power_off) {
+ unregister_sys_off_handler(platform_power_off_handler);
+ platform_power_off_handler = NULL;
+ }
+}
+EXPORT_SYMBOL_GPL(unregister_platform_power_off);
+
+static int legacy_pm_power_off(struct sys_off_data *data)
+{
+ if (pm_power_off)
+ pm_power_off();
+
+ return NOTIFY_DONE;
+}
+
+static void do_kernel_power_off_prepare(void)
+{
+ blocking_notifier_call_chain(&power_off_prep_handler_list, 0, NULL);
+}
+
+/**
+ * do_kernel_power_off - Execute kernel power-off handler call chain
+ *
+ * Expected to be called as last step of the power-off sequence.
+ *
+ * Powers off the system immediately if a power-off handler function has
+ * been registered. Otherwise does nothing.
+ */
+void do_kernel_power_off(void)
+{
+ struct sys_off_handler *sys_off = NULL;
+
+ /*
+ * Register sys-off handlers for legacy PM callback. This allows
+ * legacy PM callbacks temporary co-exist with the new sys-off API.
+ *
+ * TODO: Remove legacy handlers once all legacy PM users will be
+ * switched to the sys-off based APIs.
+ */
+ if (pm_power_off)
+ sys_off = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF,
+ SYS_OFF_PRIO_DEFAULT,
+ legacy_pm_power_off, NULL);
+
+ atomic_notifier_call_chain(&power_off_handler_list, 0, NULL);
+
+ unregister_sys_off_handler(sys_off);
+}
+
+/**
+ * kernel_can_power_off - check whether system can be powered off
+ *
+ * Returns true if power-off handler is registered and system can be
+ * powered off, false otherwise.
+ */
+bool kernel_can_power_off(void)
+{
+ return !atomic_notifier_call_chain_is_empty(&power_off_handler_list) ||
+ pm_power_off;
+}
+EXPORT_SYMBOL_GPL(kernel_can_power_off);
+
+/**
+ * kernel_power_off - power_off the system
+ *
+ * Shutdown everything and perform a clean system power_off.
+ */
+void kernel_power_off(void)
+{
+ kernel_shutdown_prepare(SYSTEM_POWER_OFF);
+ do_kernel_power_off_prepare();
+ migrate_to_reboot_cpu();
+ syscore_shutdown();
+ pr_emerg("Power down\n");
+ kmsg_dump(KMSG_DUMP_SHUTDOWN);
+ machine_power_off();
+}
+EXPORT_SYMBOL_GPL(kernel_power_off);
+
+DEFINE_MUTEX(system_transition_mutex);
+
+/*
+ * Reboot system call: for obvious reasons only root may call it,
+ * and even root needs to set up some magic numbers in the registers
+ * so that some mistake won't make this reboot the whole machine.
+ * You can also set the meaning of the ctrl-alt-del-key here.
+ *
+ * reboot doesn't sync: do that yourself before calling this.
+ */
+SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
+ void __user *, arg)
+{
+ struct pid_namespace *pid_ns = task_active_pid_ns(current);
+ char buffer[256];
+ int ret = 0;
+
+ /* We only trust the superuser with rebooting the system. */
+ if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT))
+ return -EPERM;
+
+ /* For safety, we require "magic" arguments. */
+ if (magic1 != LINUX_REBOOT_MAGIC1 ||
+ (magic2 != LINUX_REBOOT_MAGIC2 &&
+ magic2 != LINUX_REBOOT_MAGIC2A &&
+ magic2 != LINUX_REBOOT_MAGIC2B &&
+ magic2 != LINUX_REBOOT_MAGIC2C))
+ return -EINVAL;
+
+ /*
+ * If pid namespaces are enabled and the current task is in a child
+ * pid_namespace, the command is handled by reboot_pid_ns() which will
+ * call do_exit().
+ */
+ ret = reboot_pid_ns(pid_ns, cmd);
+ if (ret)
+ return ret;
+
+ /* Instead of trying to make the power_off code look like
+ * halt when pm_power_off is not set do it the easy way.
+ */
+ if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !kernel_can_power_off())
+ cmd = LINUX_REBOOT_CMD_HALT;
+
+ mutex_lock(&system_transition_mutex);
+ switch (cmd) {
+ case LINUX_REBOOT_CMD_RESTART:
+ kernel_restart(NULL);
+ break;
+
+ case LINUX_REBOOT_CMD_CAD_ON:
+ C_A_D = 1;
+ break;
+
+ case LINUX_REBOOT_CMD_CAD_OFF:
+ C_A_D = 0;
+ break;
+
+ case LINUX_REBOOT_CMD_HALT:
+ kernel_halt();
+ do_exit(0);
+
+ case LINUX_REBOOT_CMD_POWER_OFF:
+ kernel_power_off();
+ do_exit(0);
+ break;
+
+ case LINUX_REBOOT_CMD_RESTART2:
+ ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1);
+ if (ret < 0) {
+ ret = -EFAULT;
+ break;
+ }
+ buffer[sizeof(buffer) - 1] = '\0';
+
+ kernel_restart(buffer);
+ break;
+
+#ifdef CONFIG_KEXEC_CORE
+ case LINUX_REBOOT_CMD_KEXEC:
+ ret = kernel_kexec();
+ break;
+#endif
+
+#ifdef CONFIG_HIBERNATION
+ case LINUX_REBOOT_CMD_SW_SUSPEND:
+ ret = hibernate();
+ break;
+#endif
+
+ default:
+ ret = -EINVAL;
+ break;
+ }
+ mutex_unlock(&system_transition_mutex);
+ return ret;
+}
+
+static void deferred_cad(struct work_struct *dummy)
+{
+ kernel_restart(NULL);
+}
+
+/*
+ * This function gets called by ctrl-alt-del - ie the keyboard interrupt.
+ * As it's called within an interrupt, it may NOT sync: the only choice
+ * is whether to reboot at once, or just ignore the ctrl-alt-del.
+ */
+void ctrl_alt_del(void)
+{
+ static DECLARE_WORK(cad_work, deferred_cad);
+
+ if (C_A_D)
+ schedule_work(&cad_work);
+ else
+ kill_cad_pid(SIGINT, 1);
+}
+
+#define POWEROFF_CMD_PATH_LEN 256
+static char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
+static const char reboot_cmd[] = "/sbin/reboot";
+
+static int run_cmd(const char *cmd)
+{
+ char **argv;
+ static char *envp[] = {
+ "HOME=/",
+ "PATH=/sbin:/bin:/usr/sbin:/usr/bin",
+ NULL
+ };
+ int ret;
+ argv = argv_split(GFP_KERNEL, cmd, NULL);
+ if (argv) {
+ ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
+ argv_free(argv);
+ } else {
+ ret = -ENOMEM;
+ }
+
+ return ret;
+}
+
+static int __orderly_reboot(void)
+{
+ int ret;
+
+ ret = run_cmd(reboot_cmd);
+
+ if (ret) {
+ pr_warn("Failed to start orderly reboot: forcing the issue\n");
+ emergency_sync();
+ kernel_restart(NULL);
+ }
+
+ return ret;
+}
+
+static int __orderly_poweroff(bool force)
+{
+ int ret;
+
+ ret = run_cmd(poweroff_cmd);
+
+ if (ret && force) {
+ pr_warn("Failed to start orderly shutdown: forcing the issue\n");
+
+ /*
+ * I guess this should try to kick off some daemon to sync and
+ * poweroff asap. Or not even bother syncing if we're doing an
+ * emergency shutdown?
+ */
+ emergency_sync();
+ kernel_power_off();
+ }
+
+ return ret;
+}
+
+static bool poweroff_force;
+
+static void poweroff_work_func(struct work_struct *work)
+{
+ __orderly_poweroff(poweroff_force);
+}
+
+static DECLARE_WORK(poweroff_work, poweroff_work_func);
+
+/**
+ * orderly_poweroff - Trigger an orderly system poweroff
+ * @force: force poweroff if command execution fails
+ *
+ * This may be called from any context to trigger a system shutdown.
+ * If the orderly shutdown fails, it will force an immediate shutdown.
+ */
+void orderly_poweroff(bool force)
+{
+ if (force) /* do not override the pending "true" */
+ poweroff_force = true;
+ schedule_work(&poweroff_work);
+}
+EXPORT_SYMBOL_GPL(orderly_poweroff);
+
+static void reboot_work_func(struct work_struct *work)
+{
+ __orderly_reboot();
+}
+
+static DECLARE_WORK(reboot_work, reboot_work_func);
+
+/**
+ * orderly_reboot - Trigger an orderly system reboot
+ *
+ * This may be called from any context to trigger a system reboot.
+ * If the orderly reboot fails, it will force an immediate reboot.
+ */
+void orderly_reboot(void)
+{
+ schedule_work(&reboot_work);
+}
+EXPORT_SYMBOL_GPL(orderly_reboot);
+
+/**
+ * hw_failure_emergency_poweroff_func - emergency poweroff work after a known delay
+ * @work: work_struct associated with the emergency poweroff function
+ *
+ * This function is called in very critical situations to force
+ * a kernel poweroff after a configurable timeout value.
+ */
+static void hw_failure_emergency_poweroff_func(struct work_struct *work)
+{
+ /*
+ * We have reached here after the emergency shutdown waiting period has
+ * expired. This means orderly_poweroff has not been able to shut off
+ * the system for some reason.
+ *
+ * Try to shut down the system immediately using kernel_power_off
+ * if populated
+ */
+ pr_emerg("Hardware protection timed-out. Trying forced poweroff\n");
+ kernel_power_off();
+
+ /*
+ * Worst of the worst case trigger emergency restart
+ */
+ pr_emerg("Hardware protection shutdown failed. Trying emergency restart\n");
+ emergency_restart();
+}
+
+static DECLARE_DELAYED_WORK(hw_failure_emergency_poweroff_work,
+ hw_failure_emergency_poweroff_func);
+
+/**
+ * hw_failure_emergency_poweroff - Trigger an emergency system poweroff
+ *
+ * This may be called from any critical situation to trigger a system shutdown
+ * after a given period of time. If time is negative this is not scheduled.
+ */
+static void hw_failure_emergency_poweroff(int poweroff_delay_ms)
+{
+ if (poweroff_delay_ms <= 0)
+ return;
+ schedule_delayed_work(&hw_failure_emergency_poweroff_work,
+ msecs_to_jiffies(poweroff_delay_ms));
+}
+
+/**
+ * hw_protection_shutdown - Trigger an emergency system poweroff
+ *
+ * @reason: Reason of emergency shutdown to be printed.
+ * @ms_until_forced: Time to wait for orderly shutdown before tiggering a
+ * forced shudown. Negative value disables the forced
+ * shutdown.
+ *
+ * Initiate an emergency system shutdown in order to protect hardware from
+ * further damage. Usage examples include a thermal protection or a voltage or
+ * current regulator failures.
+ * NOTE: The request is ignored if protection shutdown is already pending even
+ * if the previous request has given a large timeout for forced shutdown.
+ * Can be called from any context.
+ */
+void hw_protection_shutdown(const char *reason, int ms_until_forced)
+{
+ static atomic_t allow_proceed = ATOMIC_INIT(1);
+
+ pr_emerg("HARDWARE PROTECTION shutdown (%s)\n", reason);
+
+ /* Shutdown should be initiated only once. */
+ if (!atomic_dec_and_test(&allow_proceed))
+ return;
+
+ /*
+ * Queue a backup emergency shutdown in the event of
+ * orderly_poweroff failure
+ */
+ hw_failure_emergency_poweroff(ms_until_forced);
+ orderly_poweroff(true);
+}
+EXPORT_SYMBOL_GPL(hw_protection_shutdown);
+
+static int __init reboot_setup(char *str)
+{
+ for (;;) {
+ enum reboot_mode *mode;
+
+ /*
+ * Having anything passed on the command line via
+ * reboot= will cause us to disable DMI checking
+ * below.
+ */
+ reboot_default = 0;
+
+ if (!strncmp(str, "panic_", 6)) {
+ mode = &panic_reboot_mode;
+ str += 6;
+ } else {
+ mode = &reboot_mode;
+ }
+
+ switch (*str) {
+ case 'w':
+ *mode = REBOOT_WARM;
+ break;
+
+ case 'c':
+ *mode = REBOOT_COLD;
+ break;
+
+ case 'h':
+ *mode = REBOOT_HARD;
+ break;
+
+ case 's':
+ /*
+ * reboot_cpu is s[mp]#### with #### being the processor
+ * to be used for rebooting. Skip 's' or 'smp' prefix.
+ */
+ str += str[1] == 'm' && str[2] == 'p' ? 3 : 1;
+
+ if (isdigit(str[0])) {
+ int cpu = simple_strtoul(str, NULL, 0);
+
+ if (cpu >= num_possible_cpus()) {
+ pr_err("Ignoring the CPU number in reboot= option. "
+ "CPU %d exceeds possible cpu number %d\n",
+ cpu, num_possible_cpus());
+ break;
+ }
+ reboot_cpu = cpu;
+ } else
+ *mode = REBOOT_SOFT;
+ break;
+
+ case 'g':
+ *mode = REBOOT_GPIO;
+ break;
+
+ case 'b':
+ case 'a':
+ case 'k':
+ case 't':
+ case 'e':
+ case 'p':
+ reboot_type = *str;
+ break;
+
+ case 'f':
+ reboot_force = 1;
+ break;
+ }
+
+ str = strchr(str, ',');
+ if (str)
+ str++;
+ else
+ break;
+ }
+ return 1;
+}
+__setup("reboot=", reboot_setup);
+
+#ifdef CONFIG_SYSFS
+
+#define REBOOT_COLD_STR "cold"
+#define REBOOT_WARM_STR "warm"
+#define REBOOT_HARD_STR "hard"
+#define REBOOT_SOFT_STR "soft"
+#define REBOOT_GPIO_STR "gpio"
+#define REBOOT_UNDEFINED_STR "undefined"
+
+#define BOOT_TRIPLE_STR "triple"
+#define BOOT_KBD_STR "kbd"
+#define BOOT_BIOS_STR "bios"
+#define BOOT_ACPI_STR "acpi"
+#define BOOT_EFI_STR "efi"
+#define BOOT_PCI_STR "pci"
+
+static ssize_t mode_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+{
+ const char *val;
+
+ switch (reboot_mode) {
+ case REBOOT_COLD:
+ val = REBOOT_COLD_STR;
+ break;
+ case REBOOT_WARM:
+ val = REBOOT_WARM_STR;
+ break;
+ case REBOOT_HARD:
+ val = REBOOT_HARD_STR;
+ break;
+ case REBOOT_SOFT:
+ val = REBOOT_SOFT_STR;
+ break;
+ case REBOOT_GPIO:
+ val = REBOOT_GPIO_STR;
+ break;
+ default:
+ val = REBOOT_UNDEFINED_STR;
+ }
+
+ return sprintf(buf, "%s\n", val);
+}
+static ssize_t mode_store(struct kobject *kobj, struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ if (!capable(CAP_SYS_BOOT))
+ return -EPERM;
+
+ if (!strncmp(buf, REBOOT_COLD_STR, strlen(REBOOT_COLD_STR)))
+ reboot_mode = REBOOT_COLD;
+ else if (!strncmp(buf, REBOOT_WARM_STR, strlen(REBOOT_WARM_STR)))
+ reboot_mode = REBOOT_WARM;
+ else if (!strncmp(buf, REBOOT_HARD_STR, strlen(REBOOT_HARD_STR)))
+ reboot_mode = REBOOT_HARD;
+ else if (!strncmp(buf, REBOOT_SOFT_STR, strlen(REBOOT_SOFT_STR)))
+ reboot_mode = REBOOT_SOFT;
+ else if (!strncmp(buf, REBOOT_GPIO_STR, strlen(REBOOT_GPIO_STR)))
+ reboot_mode = REBOOT_GPIO;
+ else
+ return -EINVAL;
+
+ reboot_default = 0;
+
+ return count;
+}
+static struct kobj_attribute reboot_mode_attr = __ATTR_RW(mode);
+
+#ifdef CONFIG_X86
+static ssize_t force_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%d\n", reboot_force);
+}
+static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ bool res;
+
+ if (!capable(CAP_SYS_BOOT))
+ return -EPERM;
+
+ if (kstrtobool(buf, &res))
+ return -EINVAL;
+
+ reboot_default = 0;
+ reboot_force = res;
+
+ return count;
+}
+static struct kobj_attribute reboot_force_attr = __ATTR_RW(force);
+
+static ssize_t type_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+{
+ const char *val;
+
+ switch (reboot_type) {
+ case BOOT_TRIPLE:
+ val = BOOT_TRIPLE_STR;
+ break;
+ case BOOT_KBD:
+ val = BOOT_KBD_STR;
+ break;
+ case BOOT_BIOS:
+ val = BOOT_BIOS_STR;
+ break;
+ case BOOT_ACPI:
+ val = BOOT_ACPI_STR;
+ break;
+ case BOOT_EFI:
+ val = BOOT_EFI_STR;
+ break;
+ case BOOT_CF9_FORCE:
+ val = BOOT_PCI_STR;
+ break;
+ default:
+ val = REBOOT_UNDEFINED_STR;
+ }
+
+ return sprintf(buf, "%s\n", val);
+}
+static ssize_t type_store(struct kobject *kobj, struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ if (!capable(CAP_SYS_BOOT))
+ return -EPERM;
+
+ if (!strncmp(buf, BOOT_TRIPLE_STR, strlen(BOOT_TRIPLE_STR)))
+ reboot_type = BOOT_TRIPLE;
+ else if (!strncmp(buf, BOOT_KBD_STR, strlen(BOOT_KBD_STR)))
+ reboot_type = BOOT_KBD;
+ else if (!strncmp(buf, BOOT_BIOS_STR, strlen(BOOT_BIOS_STR)))
+ reboot_type = BOOT_BIOS;
+ else if (!strncmp(buf, BOOT_ACPI_STR, strlen(BOOT_ACPI_STR)))
+ reboot_type = BOOT_ACPI;
+ else if (!strncmp(buf, BOOT_EFI_STR, strlen(BOOT_EFI_STR)))
+ reboot_type = BOOT_EFI;
+ else if (!strncmp(buf, BOOT_PCI_STR, strlen(BOOT_PCI_STR)))
+ reboot_type = BOOT_CF9_FORCE;
+ else
+ return -EINVAL;
+
+ reboot_default = 0;
+
+ return count;
+}
+static struct kobj_attribute reboot_type_attr = __ATTR_RW(type);
+#endif
+
+#ifdef CONFIG_SMP
+static ssize_t cpu_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%d\n", reboot_cpu);
+}
+static ssize_t cpu_store(struct kobject *kobj, struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ unsigned int cpunum;
+ int rc;
+
+ if (!capable(CAP_SYS_BOOT))
+ return -EPERM;
+
+ rc = kstrtouint(buf, 0, &cpunum);
+
+ if (rc)
+ return rc;
+
+ if (cpunum >= num_possible_cpus())
+ return -ERANGE;
+
+ reboot_default = 0;
+ reboot_cpu = cpunum;
+
+ return count;
+}
+static struct kobj_attribute reboot_cpu_attr = __ATTR_RW(cpu);
+#endif
+
+static struct attribute *reboot_attrs[] = {
+ &reboot_mode_attr.attr,
+#ifdef CONFIG_X86
+ &reboot_force_attr.attr,
+ &reboot_type_attr.attr,
+#endif
+#ifdef CONFIG_SMP
+ &reboot_cpu_attr.attr,
+#endif
+ NULL,
+};
+
+#ifdef CONFIG_SYSCTL
+static struct ctl_table kern_reboot_table[] = {
+ {
+ .procname = "poweroff_cmd",
+ .data = &poweroff_cmd,
+ .maxlen = POWEROFF_CMD_PATH_LEN,
+ .mode = 0644,
+ .proc_handler = proc_dostring,
+ },
+ {
+ .procname = "ctrl-alt-del",
+ .data = &C_A_D,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
+ { }
+};
+
+static void __init kernel_reboot_sysctls_init(void)
+{
+ register_sysctl_init("kernel", kern_reboot_table);
+}
+#else
+#define kernel_reboot_sysctls_init() do { } while (0)
+#endif /* CONFIG_SYSCTL */
+
+static const struct attribute_group reboot_attr_group = {
+ .attrs = reboot_attrs,
+};
+
+static int __init reboot_ksysfs_init(void)
+{
+ struct kobject *reboot_kobj;
+ int ret;
+
+ reboot_kobj = kobject_create_and_add("reboot", kernel_kobj);
+ if (!reboot_kobj)
+ return -ENOMEM;
+
+ ret = sysfs_create_group(reboot_kobj, &reboot_attr_group);
+ if (ret) {
+ kobject_put(reboot_kobj);
+ return ret;
+ }
+
+ kernel_reboot_sysctls_init();
+
+ return 0;
+}
+late_initcall(reboot_ksysfs_init);
+
+#endif