m68k: set register a2 to current if MMU enabled on ColdFire

Virtual memory m68k systems build with register a2 dedicated to being the
current proc pointer (non-MMU don't do this). Add code to the ColdFire
interrupt and exception processing to set this on entry, and at context
switch time. We use the same GET_CURRENT() macro that MMU enabled code
uses - modifying it so that the assembler is ColdFire clean.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Acked-by: Matt Waddel <mwaddel@yahoo.com>
Acked-by: Kurt Mahan <kmahan@xmission.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>

arch/m68k/include/asm/entry.h

@@ -222,16 +222,24 @@
  * Non-MMU systems do not reserve %a2 in this way, and this definition is
  * not used for them.
  */
+#ifdef CONFIG_MMU
+
 #define curptr a2
 
 #define GET_CURRENT(tmp) get_current tmp
 .macro get_current reg=%d0
 	movel	%sp,\reg
-	andw	#-THREAD_SIZE,\reg
+	andl	#-THREAD_SIZE,\reg
 	movel	\reg,%curptr
 	movel	%curptr@,%curptr
 .endm
 
+#else
+
+#define GET_CURRENT(tmp)
+
+#endif /* CONFIG_MMU */
+
 #else /* C source */
 
 #define STR(X) STR1(X)

arch/m68k/kernel/entry_no.S

@@ -44,13 +44,15 @@
 
 ENTRY(buserr)
 	SAVE_ALL_INT
+	GET_CURRENT(%d0)
 	movel	%sp,%sp@- 		/* stack frame pointer argument */
 	jsr	buserr_c
 	addql	#4,%sp
 	jra	ret_from_exception
 
 ENTRY(trap)
 	SAVE_ALL_INT
+	GET_CURRENT(%d0)
 	movel	%sp,%sp@- 		/* stack frame pointer argument */
 	jsr	trap_c
 	addql	#4,%sp
@@ -61,6 +63,7 @@ ENTRY(trap)
 .globl dbginterrupt
 ENTRY(dbginterrupt)
 	SAVE_ALL_INT
+	GET_CURRENT(%d0)
 	movel	%sp,%sp@- 		/* stack frame pointer argument */
 	jsr	dbginterrupt_c
 	addql	#4,%sp

arch/m68k/platform/coldfire/entry.S

@@ -62,6 +62,7 @@ enosys:
 ENTRY(system_call)
 	SAVE_ALL_SYS
 	move	#0x2000,%sr		/* enable intrs again */
+	GET_CURRENT(%d2)
 
 	cmpl	#NR_syscalls,%d0
 	jcc	enosys
@@ -165,6 +166,7 @@ Lsignal_return:
  */
 ENTRY(inthandler)
 	SAVE_ALL_INT
+	GET_CURRENT(%d2)
 
 	movew	%sp@(PT_OFF_FORMATVEC),%d0 /* put exception # in d0 */
 	andl	#0x03fc,%d0		/* mask out vector only */
@@ -190,7 +192,9 @@ ENTRY(resume)
 	movel	%sp,%a0@(TASK_THREAD+THREAD_KSP) /* save kernel stack pointer */
 	RDUSP					 /* movel %usp,%a3 */
 	movel	%a3,%a0@(TASK_THREAD+THREAD_USP) /* save thread user stack */
-
+#ifdef CONFIG_MMU
+	movel	%a1,%a2				 /* set new current */
+#endif
 	movel	%a1@(TASK_THREAD+THREAD_USP),%a3 /* restore thread user stack */
 	WRUSP					 /* movel %a3,%usp */
 	movel	%a1@(TASK_THREAD+THREAD_KSP),%sp /* restore new kernel stack */