extable: Skip sorting if sorted at build time.

If the build program sortextable has already sorted the exception
table, don't sort it again.

Signed-off-by: David Daney <david.daney@cavium.com>
Link: http://lkml.kernel.org/r/1334872799-14589-3-git-send-email-ddaney.cavm@gmail.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

kernel/extable.c

@@ -35,10 +35,16 @@ DEFINE_MUTEX(text_mutex);
 extern struct exception_table_entry __start___ex_table[];
 extern struct exception_table_entry __stop___ex_table[];
 
+/* Cleared by build time tools if the table is already sorted. */
+u32 __initdata main_extable_sort_needed = 1;
+
 /* Sort the kernel's built-in exception table */
 void __init sort_main_extable(void)
 {
-	sort_extable(__start___ex_table, __stop___ex_table);
+	if (main_extable_sort_needed)
+		sort_extable(__start___ex_table, __stop___ex_table);
+	else
+		pr_notice("__ex_table already sorted, skipping sort\n");
 }
 
 /* Given an address, look for it in the exception tables. */