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ARM: 8728/1: B15: Register reboot notifier for KEXEC

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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: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Florian Fainelli 2017-12-01 01:10:13 +01:00 committed by Russell King
parent 534f5f36a2
commit 576a086022
1 changed files with 44 additions and 0 deletions
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44
arch/arm/mm/cache-b15-rac.c
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@ -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);