[PATCH] x68: consolidate code segment base calculation

Calculating the base address of the segment is tricky and is used in
several places as well.  This patch moves this tricky part in a common
place as suggested by Andi Kleen.
Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/i386/kernel/kprobes.c

@@ -31,6 +31,7 @@
 #include <linux/spinlock.h>
 #include <linux/preempt.h>
 #include <asm/kdebug.h>
+#include <asm/desc.h>
 
 /* kprobe_status settings */
 #define KPROBE_HIT_ACTIVE	0x00000001
@@ -101,10 +102,8 @@ static int kprobe_handler(struct pt_regs *regs)
 	if ((regs->xcs & 4) && (current->mm)) {
 		lp = (unsigned long *) ((unsigned long)((regs->xcs >> 3) * 8)
 					+ (char *) current->mm->context.ldt);
-		addr = (kprobe_opcode_t *) ((((*lp) >> 16 &  0x0000ffff)
-				| (*(lp +1) & 0xff000000)
-				| ((*(lp +1) << 16) & 0x00ff0000))
-				+ regs->eip - sizeof(kprobe_opcode_t));
+		addr = (kprobe_opcode_t *) (get_desc_base(lp) + regs->eip -
+						sizeof(kprobe_opcode_t));
 	} else {
 		addr = (kprobe_opcode_t *)(regs->eip - sizeof(kprobe_opcode_t));
 	}

arch/i386/mm/fault.c

@@ -112,9 +112,7 @@ static inline unsigned long get_segment_eip(struct pt_regs *regs,
 	}
 
 	/* Decode the code segment base from the descriptor */
-	base =   (desc[0] >> 16) |
-		((desc[1] & 0xff) << 16) |
-		 (desc[1] & 0xff000000);
+	base = get_desc_base((unsigned long *)desc);
 
 	if (seg & (1<<2)) { 
 		up(&current->mm->context.sem);

include/asm-i386/desc.h

@@ -126,6 +126,15 @@ static inline void load_LDT(mm_context_t *pc)
 	put_cpu();
 }
 
+static inline unsigned long get_desc_base(unsigned long *desc)
+{
+	unsigned long base;
+	base = ((desc[0] >> 16)  & 0x0000ffff) |
+		((desc[1] << 16) & 0x00ff0000) |
+		(desc[1] & 0xff000000);
+	return base;
+}
+
 #endif /* !__ASSEMBLY__ */
 
 #endif