LXR linux/arch/arm/kernel/reboot.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  Copyright (C) 1996-2000 Russell King - Converted to ARM.
   4 *  Original Copyright (C) 1995  Linus Torvalds
   5 */
   6#include <linux/cpu.h>
   7#include <linux/delay.h>
   8#include <linux/reboot.h>
   9
  10#include <asm/cacheflush.h>
  11#include <asm/idmap.h>
  12#include <asm/virt.h>
  13
  14#include "reboot.h"
  15
  16typedef void (*phys_reset_t)(unsigned long, bool);
  17
  18/*
  19 * Function pointers to optional machine specific functions
  20 */
  21void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
  22void (*pm_power_off)(void);
  23EXPORT_SYMBOL(pm_power_off);
  24
  25/*
  26 * A temporary stack to use for CPU reset. This is static so that we
  27 * don't clobber it with the identity mapping. When running with this
  28 * stack, any references to the current task *will not work* so you
  29 * should really do as little as possible before jumping to your reset
  30 * code.
  31 */
  32static u64 soft_restart_stack[16];
  33
  34static void __soft_restart(void *addr)
  35{
  36        phys_reset_t phys_reset;
  37
  38        /* Take out a flat memory mapping. */
  39        setup_mm_for_reboot();
  40
  41        /* Clean and invalidate caches */
  42        flush_cache_all();
  43
  44        /* Turn off caching */
  45        cpu_proc_fin();
  46
  47        /* Push out any further dirty data, and ensure cache is empty */
  48        flush_cache_all();
  49
  50        /* Switch to the identity mapping. */
  51        phys_reset = (phys_reset_t)virt_to_idmap(cpu_reset);
  52
  53        /* original stub should be restored by kvm */
  54        phys_reset((unsigned long)addr, is_hyp_mode_available());
  55
  56        /* Should never get here. */
  57        BUG();
  58}
  59
  60void _soft_restart(unsigned long addr, bool disable_l2)
  61{
  62        u64 *stack = soft_restart_stack + ARRAY_SIZE(soft_restart_stack);
  63
  64        /* Disable interrupts first */
  65        raw_local_irq_disable();
  66        local_fiq_disable();
  67
  68        /* Disable the L2 if we're the last man standing. */
  69        if (disable_l2)
  70                outer_disable();
  71
  72        /* Change to the new stack and continue with the reset. */
  73        call_with_stack(__soft_restart, (void *)addr, (void *)stack);
  74
  75        /* Should never get here. */
  76        BUG();
  77}
  78
  79void soft_restart(unsigned long addr)
  80{
  81        _soft_restart(addr, num_online_cpus() == 1);
  82}
  83
  84/*
  85 * Called by kexec, immediately prior to machine_kexec().
  86 *
  87 * This must completely disable all secondary CPUs; simply causing those CPUs
  88 * to execute e.g. a RAM-based pin loop is not sufficient. This allows the
  89 * kexec'd kernel to use any and all RAM as it sees fit, without having to
  90 * avoid any code or data used by any SW CPU pin loop. The CPU hotplug
  91 * functionality embodied in disable_nonboot_cpus() to achieve this.
  92 */
  93void machine_shutdown(void)
  94{
  95        disable_nonboot_cpus();
  96}
  97
  98/*
  99 * Halting simply requires that the secondary CPUs stop performing any
 100 * activity (executing tasks, handling interrupts). smp_send_stop()
 101 * achieves this.
 102 */
 103void machine_halt(void)
 104{
 105        local_irq_disable();
 106        smp_send_stop();
 107        while (1);
 108}
 109
 110/*
 111 * Power-off simply requires that the secondary CPUs stop performing any
 112 * activity (executing tasks, handling interrupts). smp_send_stop()
 113 * achieves this. When the system power is turned off, it will take all CPUs
 114 * with it.
 115 */
 116void machine_power_off(void)
 117{
 118        local_irq_disable();
 119        smp_send_stop();
 120
 121        if (pm_power_off)
 122                pm_power_off();
 123}
 124
 125/*
 126 * Restart requires that the secondary CPUs stop performing any activity
 127 * while the primary CPU resets the system. Systems with a single CPU can
 128 * use soft_restart() as their machine descriptor's .restart hook, since that
 129 * will cause the only available CPU to reset. Systems with multiple CPUs must
 130 * provide a HW restart implementation, to ensure that all CPUs reset at once.
 131 * This is required so that any code running after reset on the primary CPU
 132 * doesn't have to co-ordinate with other CPUs to ensure they aren't still
 133 * executing pre-reset code, and using RAM that the primary CPU's code wishes
 134 * to use. Implementing such co-ordination would be essentially impossible.
 135 */
 136void machine_restart(char *cmd)
 137{
 138        local_irq_disable();
 139        smp_send_stop();
 140
 141        if (arm_pm_restart)
 142                arm_pm_restart(reboot_mode, cmd);
 143        else
 144                do_kernel_restart(cmd);
 145
 146        /* Give a grace period for failure to restart of 1s */
 147        mdelay(1000);
 148
 149        /* Whoops - the platform was unable to reboot. Tell the user! */
 150        printk("Reboot failed -- System halted\n");
 151        while (1);
 152}
 153