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
  16 typedef void (*phys_reset_t)(unsigned long, bool);
  17
  18 /*
  19  * Function pointers to optional machine specific functions
  20  */
  21 void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
  22 void (*pm_power_off)(void);
  23 EXPORT_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  */
  32 static u64 soft_restart_stack[16];
  33
  34 static 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
  60 void _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
  79 void 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  */
  93 void 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  */
 103 void 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  */
 116 void 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  */
 136 void 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 }