[PATCH] fix kgdb exception handler from user mode

[Atsushi Nemoto <anemo@mba.ocn.ne.jp>]

Fix a calculation of saved vector address in trap_low (damage done by
f4c72cc737561aab0d9c7f877abbc0a853f1c465)

diff --git a/arch/mips/kernel/gdb-low.S b/arch/mips/kernel/gdb-low.S
index 10f28fb..5fd7a8a 100644
--- a/arch/mips/kernel/gdb-low.S
+++ b/arch/mips/kernel/gdb-low.S
@@ -54,9 +54,11 @@ #endif
                 */
                mfc0    k0, CP0_CAUSE
                andi    k0, k0, 0x7c
-               add     k1, k1, k0
-               PTR_L   k0, saved_vectors(k1)
-               jr      k0
+#ifdef CONFIG_64BIT
+               dsll    k0, k0, 1
+#endif
+               PTR_L   k1, saved_vectors(k0)
+               jr      k1
                nop
 1:
                move    k0, sp