x86: Remove GDR related magic numbers

--
Changes for v2:
 - Use an enum
 - Add defined for GDT size (previously added in patch 7)
 - Use X86_ namespace (as per Linux headers)

arch/x86/include/asm/processor.h

@@ -24,9 +24,24 @@
 #ifndef __ASM_PROCESSOR_H_
 #define __ASM_PROCESSOR_H_ 1
 
-#define GDT_ENTRY_32BIT_CS	2
-#define GDT_ENTRY_32BIT_DS	(GDT_ENTRY_32BIT_CS + 1)
-#define GDT_ENTRY_16BIT_CS	(GDT_ENTRY_32BIT_DS + 1)
-#define GDT_ENTRY_16BIT_DS	(GDT_ENTRY_16BIT_CS + 1)
+#define X86_GDT_ENTRY_SIZE	8
+
+#ifndef __ASSEMBLY__
+
+enum {
+	X86_GDT_ENTRY_NULL = 0,
+	X86_GDT_ENTRY_UNUSED,
+	X86_GDT_ENTRY_32BIT_CS,
+	X86_GDT_ENTRY_32BIT_DS,
+	X86_GDT_ENTRY_16BIT_CS,
+	X86_GDT_ENTRY_16BIT_DS,
+	X86_GDT_NUM_ENTRIES
+};
+#else
+/* NOTE: If the above enum is modified, this define must be checked */
+#define X86_GDT_ENTRY_32BIT_DS	3
+#endif
+
+#define X86_GDT_SIZE		(X86_GDT_NUM_ENTRIES * X86_GDT_ENTRY_SIZE)
 
 #endif