| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * linux/kernel/reboot.c |
| * |
| * Copyright (C) 2013 Linus Torvalds |
| */ |
| |
| #define pr_fmt(fmt) "reboot: " fmt |
| |
| #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 |
| */ |
| |
| int C_A_D = 1; |
| struct pid *cad_pid; |
| EXPORT_SYMBOL(cad_pid); |
| |
| #if defined(CONFIG_ARM) || defined(CONFIG_UNICORE32) |
| #define DEFAULT_REBOOT_MODE = REBOOT_HARD |
| #else |
| #define DEFAULT_REBOOT_MODE |
| #endif |
| enum reboot_mode reboot_mode DEFAULT_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; |
| |
| /* |
| * If set, this is used for preparing the system to power off. |
| */ |
| |
| void (*pm_power_off_prepare)(void); |
| EXPORT_SYMBOL_GPL(pm_power_off_prepare); |
| |
| /** |
| * 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); |
| 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)); |
| } |
| |
| /** |
| * 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); |
| 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_RESTART); |
| 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_HALT); |
| machine_halt(); |
| } |
| EXPORT_SYMBOL_GPL(kernel_halt); |
| |
| /** |
| * 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); |
| if (pm_power_off_prepare) |
| pm_power_off_prepare(); |
| migrate_to_reboot_cpu(); |
| syscore_shutdown(); |
| pr_emerg("Power down\n"); |
| kmsg_dump(KMSG_DUMP_POWEROFF); |
| 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) && !pm_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); |
| panic("cannot halt"); |
| |
| 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); |
| } |
| |
| 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); |
| |
| 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': |
| if (isdigit(*(str+1))) |
| reboot_cpu = simple_strtoul(str+1, NULL, 0); |
| else if (str[1] == 'm' && str[2] == 'p' && |
| isdigit(*(str+3))) |
| reboot_cpu = simple_strtoul(str+3, NULL, 0); |
| else |
| *mode = REBOOT_SOFT; |
| if (reboot_cpu >= num_possible_cpus()) { |
| pr_err("Ignoring the CPU number in reboot= option. " |
| "CPU %d exceeds possible cpu number %d\n", |
| reboot_cpu, num_possible_cpus()); |
| reboot_cpu = 0; |
| break; |
| } |
| 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); |