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Commit 576a0860 authored by Florian Fainelli's avatar Florian Fainelli Committed by Russell King
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ARM: 8728/1: B15: Register reboot notifier for KEXEC 



During kexec, we will go through kernel_kexec() -> syscore_suspend() if
CONFIG_KEXEC_JUMP is set, if not, down the road we end-up calling
kernel_restart_prepare() which invokes reboot notifiers with
SYS_RESTART.

We register a reboot notifier to make sure that the B15 read-ahead cache
is disabled, since it is another level of instruction and data cache,
and we want to avoid any potential side effects with booting a new
kernel with such a cache still turned on.

Signed-off-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
parent 534f5f36

arch/arm/mm/cache-b15-rac.c

+44 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include <linux/notifier.h>

#include <linux/cpu.h>

#include <linux/syscore_ops.h>

#include <linux/reboot.h>



#include <asm/cacheflush.h>

#include <asm/hardware/cache-b15-rac.h>
@@ -151,6 +152,29 @@ static void b15_rac_enable(void) 
	__b15_rac_enable(enable);

}



static int b15_rac_reboot_notifier(struct notifier_block *nb,

				   unsigned long action,

				   void *data)

{

	/* During kexec, we are not yet migrated on the boot CPU, so we need to

	 * make sure we are SMP safe here. Once the RAC is disabled, flag it as

	 * suspended such that the hotplug notifier returns early.

	 */

	if (action == SYS_RESTART) {

		spin_lock(&rac_lock);

		b15_rac_disable_and_flush();

		clear_bit(RAC_ENABLED, &b15_rac_flags);

		set_bit(RAC_SUSPENDED, &b15_rac_flags);

		spin_unlock(&rac_lock);

	}



	return NOTIFY_DONE;

}



static struct notifier_block b15_rac_reboot_nb = {

	.notifier_call	= b15_rac_reboot_notifier,

};



#ifdef CONFIG_HOTPLUG_CPU

/* The CPU hotplug case is the most interesting one, we basically need to make

 * sure that the RAC is disabled for the entire system prior to having a CPU
@@ -191,6 +215,12 @@ static void b15_rac_enable(void) 
/* Running on the dying CPU */

static int b15_rac_dying_cpu(unsigned int cpu)

{

	/* During kexec/reboot, the RAC is disabled via the reboot notifier

	 * return early here.

	 */

	if (test_bit(RAC_SUSPENDED, &b15_rac_flags))

		return 0;



	spin_lock(&rac_lock);



	/* Indicate that we are starting a hotplug procedure */
@@ -207,6 +237,12 @@ static int b15_rac_dying_cpu(unsigned int cpu) 
/* Running on a non-dying CPU */

static int b15_rac_dead_cpu(unsigned int cpu)

{

	/* During kexec/reboot, the RAC is disabled via the reboot notifier

	 * return early here.

	 */

	if (test_bit(RAC_SUSPENDED, &b15_rac_flags))

		return 0;



	spin_lock(&rac_lock);



	/* And enable it */
@@ -272,6 +308,13 @@ static int __init b15_rac_init(void) 
		goto out;

	}



	ret = register_reboot_notifier(&b15_rac_reboot_nb);

	if (ret) {

		pr_err("failed to register reboot notifier\n");

		iounmap(b15_rac_base);

		goto out;

	}



#ifdef CONFIG_HOTPLUG_CPU

	ret = cpuhp_setup_state_nocalls(CPUHP_AP_ARM_CACHE_B15_RAC_DEAD,

					"arm/cache-b15-rac:dead",
@@ -308,6 +351,7 @@ static int __init b15_rac_init(void) 
out_cpu_dead:

	cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CACHE_B15_RAC_DYING);

out_unmap:

	unregister_reboot_notifier(&b15_rac_reboot_nb);

	iounmap(b15_rac_base);

out:

	of_node_put(dn);