MIPS: Add board_ebase_setup()

Some systems need to relocate the MIPS exception vector base during
trap initialization.  Add a hook to make this possible.
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2959/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/traps.h

@@ -24,6 +24,7 @@ extern int (*board_be_handler)(struct pt_regs *regs, int is_fixup);
 extern void (*board_nmi_handler_setup)(void);
 extern void (*board_ejtag_handler_setup)(void);
 extern void (*board_bind_eic_interrupt)(int irq, int regset);
+extern void (*board_ebase_setup)(void);
 
 extern int register_nmi_notifier(struct notifier_block *nb);
 

arch/mips/kernel/traps.c

@@ -91,6 +91,7 @@ int (*board_be_handler)(struct pt_regs *regs, int is_fixup);
 void (*board_nmi_handler_setup)(void);
 void (*board_ejtag_handler_setup)(void);
 void (*board_bind_eic_interrupt)(int irq, int regset);
+void (*board_ebase_setup)(void);
 
 
 static void show_raw_backtrace(unsigned long reg29)
@@ -1691,6 +1692,8 @@ void __init trap_init(void)
 			ebase += (read_c0_ebase() & 0x3ffff000);
 	}
 
+	if (board_ebase_setup)
+		board_ebase_setup();
 	per_cpu_trap_init();
 
 	/*