[PATCH] fix Thread-Local Storage GDT access

The gdt entry is consulted only while loading its index into
the segment register.

So load_TLS_desc(next, cpu) must be called before loading
next->fs,next->gs in __switch_to().

arch/i386/kernel/process.c

@@ -674,6 +674,14 @@ void __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 	 */
 	tss->esp0 = next->esp0;
 
+	/*
+	 * Load the per-thread Thread-Local Storage descriptor.
+	 *
+	 * NOTE: it's faster to do the two stores unconditionally
+	 * than to branch away.
+	 */
+	load_TLS_desc(next, cpu);
+
 	/*
 	 * Save away %fs and %gs. No need to save %es and %ds, as
 	 * those are always kernel segments while inside the kernel.
@@ -689,14 +697,6 @@ void __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 		loadsegment(gs, next->gs);
 	}
 
-	/*
-	 * Load the per-thread Thread-Local Storage descriptor.
-	 *
-	 * NOTE: it's faster to do the two stores unconditionally
-	 * than to branch away.
-	 */
-	load_TLS_desc(next, cpu);
-
 	/*
 	 * Now maybe reload the debug registers
 	 */