![Russell King](/assets/img/avatar_default.png)
When we soft-reboot (eg, kexec) from one kernel into the next, we need to ensure that we enter the new kernel in the same processor mode as when we were entered, so that (eg) the new kernel can install its own hypervisor - the old kernel's hypervisor will have been overwritten. In order to do this, we need to pass a flag to cpu_reset() so it knows what to do, and we need to modify the kernel's own hypervisor stub to allow it to handle a soft-reboot. As we are always guaranteed to install our own hypervisor if we're entered in HYP32 mode, and KVM will have moved itself out of the way on kexec/normal reboot, we can assume that our hypervisor is in place when we want to kexec, so changing our hypervisor API should not be a problem. Tested-by: Keerthy <j-keerthy@ti.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Christoffer Dall <cdall@linaro.org>
156 lines
4.2 KiB
C
156 lines
4.2 KiB
C
/*
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* Copyright (C) 1996-2000 Russell King - Converted to ARM.
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* Original Copyright (C) 1995 Linus Torvalds
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/cpu.h>
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#include <linux/delay.h>
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#include <linux/reboot.h>
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#include <asm/cacheflush.h>
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#include <asm/idmap.h>
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#include <asm/virt.h>
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#include "reboot.h"
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typedef void (*phys_reset_t)(unsigned long, bool);
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/*
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* Function pointers to optional machine specific functions
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*/
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void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
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void (*pm_power_off)(void);
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EXPORT_SYMBOL(pm_power_off);
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/*
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* A temporary stack to use for CPU reset. This is static so that we
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* don't clobber it with the identity mapping. When running with this
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* stack, any references to the current task *will not work* so you
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* should really do as little as possible before jumping to your reset
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* code.
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*/
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static u64 soft_restart_stack[16];
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static void __soft_restart(void *addr)
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{
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phys_reset_t phys_reset;
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/* Take out a flat memory mapping. */
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setup_mm_for_reboot();
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/* Clean and invalidate caches */
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flush_cache_all();
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/* Turn off caching */
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cpu_proc_fin();
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/* Push out any further dirty data, and ensure cache is empty */
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flush_cache_all();
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/* Switch to the identity mapping. */
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phys_reset = (phys_reset_t)virt_to_idmap(cpu_reset);
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/* original stub should be restored by kvm */
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phys_reset((unsigned long)addr, is_hyp_mode_available());
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/* Should never get here. */
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BUG();
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}
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void _soft_restart(unsigned long addr, bool disable_l2)
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{
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u64 *stack = soft_restart_stack + ARRAY_SIZE(soft_restart_stack);
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/* Disable interrupts first */
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raw_local_irq_disable();
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local_fiq_disable();
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/* Disable the L2 if we're the last man standing. */
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if (disable_l2)
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outer_disable();
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/* Change to the new stack and continue with the reset. */
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call_with_stack(__soft_restart, (void *)addr, (void *)stack);
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/* Should never get here. */
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BUG();
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}
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void soft_restart(unsigned long addr)
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{
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_soft_restart(addr, num_online_cpus() == 1);
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}
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/*
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* Called by kexec, immediately prior to machine_kexec().
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*
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* This must completely disable all secondary CPUs; simply causing those CPUs
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* to execute e.g. a RAM-based pin loop is not sufficient. This allows the
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* kexec'd kernel to use any and all RAM as it sees fit, without having to
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* avoid any code or data used by any SW CPU pin loop. The CPU hotplug
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* functionality embodied in disable_nonboot_cpus() to achieve this.
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*/
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void machine_shutdown(void)
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{
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disable_nonboot_cpus();
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}
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/*
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* Halting simply requires that the secondary CPUs stop performing any
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* activity (executing tasks, handling interrupts). smp_send_stop()
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* achieves this.
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*/
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void machine_halt(void)
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{
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local_irq_disable();
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smp_send_stop();
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while (1);
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}
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/*
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* Power-off simply requires that the secondary CPUs stop performing any
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* activity (executing tasks, handling interrupts). smp_send_stop()
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* achieves this. When the system power is turned off, it will take all CPUs
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* with it.
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*/
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void machine_power_off(void)
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{
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local_irq_disable();
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smp_send_stop();
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if (pm_power_off)
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pm_power_off();
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}
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/*
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* Restart requires that the secondary CPUs stop performing any activity
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* while the primary CPU resets the system. Systems with a single CPU can
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* use soft_restart() as their machine descriptor's .restart hook, since that
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* will cause the only available CPU to reset. Systems with multiple CPUs must
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* provide a HW restart implementation, to ensure that all CPUs reset at once.
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* This is required so that any code running after reset on the primary CPU
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* doesn't have to co-ordinate with other CPUs to ensure they aren't still
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* executing pre-reset code, and using RAM that the primary CPU's code wishes
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* to use. Implementing such co-ordination would be essentially impossible.
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*/
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void machine_restart(char *cmd)
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{
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local_irq_disable();
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smp_send_stop();
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if (arm_pm_restart)
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arm_pm_restart(reboot_mode, cmd);
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else
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do_kernel_restart(cmd);
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/* Give a grace period for failure to restart of 1s */
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mdelay(1000);
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/* Whoops - the platform was unable to reboot. Tell the user! */
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printk("Reboot failed -- System halted\n");
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while (1);
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}
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