m68knommu: use user stack pointer hardware on some ColdFire cores

The more modern ColdFire parts (even if based on older version cores)
have separate user and supervisor stack pointers (a7 register).
Modify the ColdFire CPU setup and exception code to enable and use
this on parts that have it.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>

1 files changed, 8 insertions, 5 deletions

diff --git a/arch/m68k/include/asm/processor.h b/arch/m68k/include/asm/processor.h
index 7a6a7590cc02..278c69bad57a 100644
--- a/arch/m68k/include/asm/processor.h
+++ b/arch/m68k/include/asm/processor.h
@@ -20,23 +20,26 @@
 
 static inline unsigned long rdusp(void)
 {
-#ifdef CONFIG_COLDFIRE
+#ifdef CONFIG_COLDFIRE_SW_A7
         extern unsigned int sw_usp;
         return sw_usp;
 #else
-        unsigned long usp;
-        __asm__ __volatile__("move %/usp,%0" : "=a" (usp));
+        register unsigned long usp __asm__("a0");
+        /* move %usp,%a0 */
+        __asm__ __volatile__(".word 0x4e68" : "=a" (usp));
         return usp;
 #endif
 }
 
 static inline void wrusp(unsigned long usp)
 {
-#ifdef CONFIG_COLDFIRE
+#ifdef CONFIG_COLDFIRE_SW_A7
         extern unsigned int sw_usp;
         sw_usp = usp;
 #else
-        __asm__ __volatile__("move %0,%/usp" : : "a" (usp));
+        register unsigned long a0 __asm__("a0") = usp;
+        /* move %a0,%usp */
+        __asm__ __volatile__(".word 0x4e60" : : "a" (a0) );
 #endif
 }