When compiling with W=1 enabling -Wmissing-prototypes the compiler
warns:

  arch/openrisc/kernel/traps.c:221:17: sing-prototypesrror: no previous prototype for 'die' [-Werror=missing-prototypes]

Fix by adding the prototype to the appropriate header file and including
the header file in the appropriate C files.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Closes: https://lore.kernel.org/linux-kernel/20230810141947.1236730-17-arnd@kernel.org/
Signed-off-by: Stafford Horne <shorne@gmail.com>
---
 arch/openrisc/include/asm/bug.h | 11 +++++++++++
 arch/openrisc/kernel/traps.c    |  1 +
 arch/openrisc/mm/fault.c        |  3 +--
 3 files changed, 13 insertions(+), 2 deletions(-)
 create mode 100644 arch/openrisc/include/asm/bug.h

diff --git a/arch/openrisc/include/asm/bug.h b/arch/openrisc/include/asm/bug.h
new file mode 100644
index 000000000000..6d04776eaf10
--- /dev/null
+++ b/arch/openrisc/include/asm/bug.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __ASM_OPENRISC_BUG_H
+#define __ASM_OPENRISC_BUG_H
+
+#include <asm-generic/bug.h>
+
+struct pt_regs;
+
+void __noreturn die(const char *str, struct pt_regs *regs, long err);
+
+#endif /* __ASM_OPENRISC_BUG_H */
diff --git a/arch/openrisc/kernel/traps.c b/arch/openrisc/kernel/traps.c
index f221e4b4298f..879fbf57c04e 100644
--- a/arch/openrisc/kernel/traps.c
+++ b/arch/openrisc/kernel/traps.c
@@ -30,6 +30,7 @@
 #include <linux/kallsyms.h>
 #include <linux/uaccess.h>
 
+#include <asm/bug.h>
 #include <asm/io.h>
 #include <asm/processor.h>
 #include <asm/unwinder.h>
diff --git a/arch/openrisc/mm/fault.c b/arch/openrisc/mm/fault.c
index 01dc18aa8410..29e232d78d82 100644
--- a/arch/openrisc/mm/fault.c
+++ b/arch/openrisc/mm/fault.c
@@ -18,6 +18,7 @@
 #include <linux/perf_event.h>
 
 #include <linux/uaccess.h>
+#include <asm/bug.h>
 #include <asm/mmu_context.h>
 #include <asm/siginfo.h>
 #include <asm/signal.h>
@@ -30,8 +31,6 @@
  */
 volatile pgd_t *current_pgd[NR_CPUS];
 
-extern void __noreturn die(char *, struct pt_regs *, long);
-
 asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long address,
 			      unsigned long vector, int write_acc);
 
-- 
2.39.1