arch/arm/kernel/reboot.c

Source file repositories/reference/linux-study-clean/arch/arm/kernel/reboot.c

File Facts

System
Linux kernel
Corpus path
arch/arm/kernel/reboot.c
Extension
.c
Size
4061 bytes
Lines
148
Domain
Architecture Layer
Bucket
arch/arm
Inferred role
Architecture Layer: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  Copyright (C) 1996-2000 Russell King - Converted to ARM.
 *  Original Copyright (C) 1995  Linus Torvalds
 */
#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/reboot.h>

#include <asm/cacheflush.h>
#include <asm/idmap.h>
#include <asm/virt.h>
#include <asm/system_misc.h>

#include "reboot.h"

typedef void (*phys_reset_t)(unsigned long, bool);

/*
 * Function pointers to optional machine specific functions
 */
void (*pm_power_off)(void);
EXPORT_SYMBOL(pm_power_off);

/*
 * A temporary stack to use for CPU reset. This is static so that we
 * don't clobber it with the identity mapping. When running with this
 * stack, any references to the current task *will not work* so you
 * should really do as little as possible before jumping to your reset
 * code.
 */
static u64 soft_restart_stack[16];

static void __soft_restart(void *addr)
{
	phys_reset_t phys_reset;

	/* Take out a flat memory mapping. */
	setup_mm_for_reboot();

	/* Clean and invalidate caches */
	flush_cache_all();

	/* Turn off caching */
	cpu_proc_fin();

	/* Push out any further dirty data, and ensure cache is empty */
	flush_cache_all();

	/* Switch to the identity mapping. */
	phys_reset = (phys_reset_t)virt_to_idmap(cpu_reset);

	/* original stub should be restored by kvm */
	phys_reset((unsigned long)addr, is_hyp_mode_available());

	/* Should never get here. */
	BUG();
}

void _soft_restart(unsigned long addr, bool disable_l2)
{
	u64 *stack = soft_restart_stack + ARRAY_SIZE(soft_restart_stack);

	/* Disable interrupts first */
	raw_local_irq_disable();
	local_fiq_disable();

	/* Disable the L2 if we're the last man standing. */
	if (disable_l2)
		outer_disable();

	/* Change to the new stack and continue with the reset. */
	call_with_stack(__soft_restart, (void *)addr, (void *)stack);

	/* Should never get here. */
	BUG();
}

void soft_restart(unsigned long addr)
{
	_soft_restart(addr, num_online_cpus() == 1);
}

/*
 * Called by kexec, immediately prior to machine_kexec().
 *
 * This must completely disable all secondary CPUs; simply causing those CPUs
 * to execute e.g. a RAM-based pin loop is not sufficient. This allows the
 * kexec'd kernel to use any and all RAM as it sees fit, without having to
 * avoid any code or data used by any SW CPU pin loop. The CPU hotplug

Annotation

Implementation Notes