#ifdef __KERNEL__
-#define STACK_TOP (test_thread_flag(TIF_32BIT) ? 0xf0000000 : 0x80000000000L)
+#define STACK_TOP32 ((1UL << 32UL) - PAGE_SIZE)
+#define STACK_TOP64 (0x0000080000000000UL - (1UL << 32UL))
+
+#define STACK_TOP (test_thread_flag(TIF_32BIT) ? \
+ STACK_TOP32 : STACK_TOP64)
#endif