ARM: 8078/1: get rid of hardcoded assumptions about kernel stack size

Changing kernel stack size on arm is not as simple as it should be:
1) THREAD_SIZE macro doesn't respect PAGE_SIZE and THREAD_SIZE_ORDER
2) stack size is hardcoded in get_thread_info macro

This patch fixes it by calculating THREAD_SIZE and thread_info address
taking into account PAGE_SIZE and THREAD_SIZE_ORDER.

Now changing stack size becomes simply changing THREAD_SIZE_ORDER.

Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index e4e4208..fc44d37 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -14,9 +14,10 @@
 
 #include <linux/compiler.h>
 #include <asm/fpstate.h>
+#include <asm/page.h>
 
 #define THREAD_SIZE_ORDER	1
-#define THREAD_SIZE		8192
+#define THREAD_SIZE		(PAGE_SIZE << THREAD_SIZE_ORDER)
 #define THREAD_START_SP		(THREAD_SIZE - 8)
 
 #ifndef __ASSEMBLY__