arm64: Add support for 32 bit app specific settings

Add support to enable app specific settings, whenever
a 32 bit application is running.

Change-Id: I0cf40e8ea6e3f9e62258a44ccdd959e9eae09d88
Signed-off-by: Imran Khan <kimran@codeaurora.org>

2 files changed, 50 insertions, 0 deletions

diff --git a/arch/arm64/kernel/app_api.c b/arch/arm64/kernel/app_api.c
index 39eeee1a9029..1b3732accd4b 100644
--- a/arch/arm64/kernel/app_api.c
+++ b/arch/arm64/kernel/app_api.c
@@ -18,6 +18,7 @@
 #include <asm/app_api.h>
 
 static spinlock_t spinlock;
+static spinlock_t spinlock_32bit_app;
 static DEFINE_PER_CPU(int, app_config_applied);
 static unsigned long app_config_set[NR_CPUS];
 static unsigned long app_config_clear[NR_CPUS];
@@ -67,9 +68,43 @@ void clear_app_setting_bit(uint32_t bit)
 }
 EXPORT_SYMBOL(clear_app_setting_bit);
 
+void set_app_setting_bit_for_32bit_apps(void)
+{
+	unsigned long flags;
+	uint64_t reg;
+
+	spin_lock_irqsave(&spinlock_32bit_app, flags);
+	asm volatile("mrs %0, S3_0_c15_c15_1 " : "=r" (reg));
+	reg = reg | BIT(18);
+	reg = reg & ~BIT(2);
+	reg = reg | 0x3;
+	isb();
+	asm volatile("msr S3_0_c15_c15_1, %0" : : "r" (reg));
+	isb();
+	spin_unlock_irqrestore(&spinlock_32bit_app, flags);
+}
+EXPORT_SYMBOL(set_app_setting_bit_for_32bit_apps);
+
+void clear_app_setting_bit_for_32bit_apps(void)
+{
+	unsigned long flags;
+	uint64_t reg;
+
+	spin_lock_irqsave(&spinlock_32bit_app, flags);
+	asm volatile("mrs %0, S3_0_c15_c15_1 " : "=r" (reg));
+	reg = reg & ~BIT(18);
+	reg = reg & ~0x3;
+	isb();
+	asm volatile("msr S3_0_c15_c15_1, %0" : : "r" (reg));
+	isb();
+	spin_unlock_irqrestore(&spinlock_32bit_app, flags);
+}
+EXPORT_SYMBOL(clear_app_setting_bit_for_32bit_apps);
+
 static int __init init_app_api(void)
 {
 	spin_lock_init(&spinlock);
+	spin_lock_init(&spinlock_32bit_app);
 	return 0;
 }
 early_initcall(init_app_api);
diff --git a/arch/arm64/kernel/app_setting.c b/arch/arm64/kernel/app_setting.c
index 6b4eb28d0e24..8e7aeab39edd 100644
--- a/arch/arm64/kernel/app_setting.c
+++ b/arch/arm64/kernel/app_setting.c
@@ -35,6 +35,10 @@ bool use_app_setting = true;
 module_param(use_app_setting, bool, 0644);
 MODULE_PARM_DESC(use_app_setting, "control use of app specific settings");
 
+bool use_32bit_app_setting = true;
+module_param(use_32bit_app_setting, bool, 0644);
+MODULE_PARM_DESC(use_32bit_app_setting, "control use of 32 bit app specific settings");
+
 static int set_name(const char *str, struct kernel_param *kp)
 {
 	int len = strlen(str);
@@ -87,6 +91,17 @@ void switch_app_setting_bit(struct task_struct *prev, struct task_struct *next)
 }
 EXPORT_SYMBOL(switch_app_setting_bit);
 
+void switch_32bit_app_setting_bit(struct task_struct *prev,
+					struct task_struct *next)
+{
+	if (prev->mm && unlikely(is_compat_thread(task_thread_info(prev))))
+		clear_app_setting_bit_for_32bit_apps();
+
+	if (next->mm && unlikely(is_compat_thread(task_thread_info(next))))
+		set_app_setting_bit_for_32bit_apps();
+}
+EXPORT_SYMBOL(switch_32bit_app_setting_bit);
+
 void apply_app_setting_bit(struct file *file)
 {
 	bool found = false;