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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: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
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1 changed files with 44 additions and 0 deletions
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@ -16,6 +16,7 @@
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#include <linux/notifier.h>
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#include <linux/cpu.h>
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#include <linux/syscore_ops.h>
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#include <linux/reboot.h>
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#include <asm/cacheflush.h>
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#include <asm/hardware/cache-b15-rac.h>
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@ -151,6 +152,29 @@ static void b15_rac_enable(void)
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__b15_rac_enable(enable);
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}
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static int b15_rac_reboot_notifier(struct notifier_block *nb,
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unsigned long action,
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void *data)
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{
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/* During kexec, we are not yet migrated on the boot CPU, so we need to
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* make sure we are SMP safe here. Once the RAC is disabled, flag it as
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* suspended such that the hotplug notifier returns early.
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*/
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if (action == SYS_RESTART) {
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spin_lock(&rac_lock);
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b15_rac_disable_and_flush();
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clear_bit(RAC_ENABLED, &b15_rac_flags);
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set_bit(RAC_SUSPENDED, &b15_rac_flags);
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spin_unlock(&rac_lock);
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}
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return NOTIFY_DONE;
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}
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static struct notifier_block b15_rac_reboot_nb = {
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.notifier_call = b15_rac_reboot_notifier,
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};
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#ifdef CONFIG_HOTPLUG_CPU
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/* The CPU hotplug case is the most interesting one, we basically need to make
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* sure that the RAC is disabled for the entire system prior to having a CPU
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@ -191,6 +215,12 @@ static void b15_rac_enable(void)
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/* Running on the dying CPU */
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static int b15_rac_dying_cpu(unsigned int cpu)
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{
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/* During kexec/reboot, the RAC is disabled via the reboot notifier
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* return early here.
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*/
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if (test_bit(RAC_SUSPENDED, &b15_rac_flags))
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return 0;
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spin_lock(&rac_lock);
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/* Indicate that we are starting a hotplug procedure */
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@ -207,6 +237,12 @@ static int b15_rac_dying_cpu(unsigned int cpu)
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/* Running on a non-dying CPU */
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static int b15_rac_dead_cpu(unsigned int cpu)
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{
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/* During kexec/reboot, the RAC is disabled via the reboot notifier
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* return early here.
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*/
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if (test_bit(RAC_SUSPENDED, &b15_rac_flags))
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return 0;
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spin_lock(&rac_lock);
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/* And enable it */
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@ -272,6 +308,13 @@ static int __init b15_rac_init(void)
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goto out;
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}
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ret = register_reboot_notifier(&b15_rac_reboot_nb);
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if (ret) {
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pr_err("failed to register reboot notifier\n");
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iounmap(b15_rac_base);
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goto out;
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}
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#ifdef CONFIG_HOTPLUG_CPU
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ret = cpuhp_setup_state_nocalls(CPUHP_AP_ARM_CACHE_B15_RAC_DEAD,
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"arm/cache-b15-rac:dead",
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@ -308,6 +351,7 @@ static int __init b15_rac_init(void)
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out_cpu_dead:
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cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CACHE_B15_RAC_DYING);
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out_unmap:
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unregister_reboot_notifier(&b15_rac_reboot_nb);
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iounmap(b15_rac_base);
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out:
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of_node_put(dn);
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