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