MN10300: Make the FPU operate in non-lazy mode under SMP

Make the FPU operate in non-lazy mode under SMP so that when the process that
is currently using the FPU migrates to a different CPU, we don't have to ping
its previous CPU to flush the FPU context.

Signed-off-by: Akira Takeuchi <takeuchi.akr@jp.panasonic.com>
Signed-off-by: Kiyoshi Owada <owada.kiyoshi@jp.panasonic.com>
Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/arch/mn10300/kernel/fpu-nofpu-low.S b/arch/mn10300/kernel/fpu-nofpu-low.S
new file mode 100644
index 000000000000..7ea087a549f4
--- /dev/null
+++ b/arch/mn10300/kernel/fpu-nofpu-low.S
@@ -0,0 +1,39 @@
+/* MN10300 Low level FPU management operations
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+#include <linux/linkage.h>
+#include <asm/cpu-regs.h>
+#include <asm/smp.h>
+#include <asm/thread_info.h>
+#include <asm/asm-offsets.h>
+#include <asm/frame.inc>
+
+###############################################################################
+#
+# void fpu_disabled(void)
+# - handle an exception due to the FPU being disabled
+#   when CONFIG_FPU is disabled
+#
+###############################################################################
+        .type   fpu_disabled,@function
+        .globl  fpu_disabled
+fpu_disabled:
+        add     -4,sp
+        SAVE_ALL
+        mov     -1,d0
+        mov     d0,(REG_ORIG_D0,fp)
+
+        and     ~EPSW_NMID,epsw
+
+        mov     fp,d0
+        call    unexpected_fpu_exception[],0
+        jmp     ret_from_exception
+
+        .size   fpu_disabled,.-fpu_disabled