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, 10 insertions, 20 deletions

diff --git a/arch/m68knommu/platform/coldfire/entry.S b/arch/m68knommu/platform/coldfire/entry.S
index b9ce31966181..f90e6173ccd4 100644
--- a/arch/m68knommu/platform/coldfire/entry.S
+++ b/arch/m68knommu/platform/coldfire/entry.S
@@ -36,13 +36,16 @@
 #include <asm/asm-offsets.h>
 #include <asm/entry.h>
 
+#ifdef CONFIG_COLDFIRE_SW_A7
+/*
+ *      Define software copies of the supervisor and user stack pointers.
+ */
 .bss
-
 sw_ksp:
 .long   0
-
 sw_usp:
 .long   0
+#endif /* CONFIG_COLDFIRE_SW_A7 */
 
 .text
 
@@ -52,6 +55,7 @@ sw_usp:
 .globl ret_from_signal
 .globl sys_call_table
 .globl inthandler
+.globl fasthandler
 
 enosys:
         mov.l   #sys_ni_syscall,%d3
@@ -138,20 +142,7 @@ Luser_return:
         jne     Lwork_to_do             /* still work to do */
 
 Lreturn:
-        move    #0x2700,%sr             /* disable intrs */
-        movel   sw_usp,%a0              /* get usp */
-        movel   %sp@(PT_OFF_PC),%a0@-   /* copy exception program counter */
-        movel   %sp@(PT_OFF_FORMATVEC),%a0@- /* copy exception format/vector/sr */
-        moveml  %sp@,%d1-%d5/%a0-%a2
-        lea     %sp@(32),%sp            /* space for 8 regs */
-        movel   %sp@+,%d0
-        addql   #4,%sp                  /* orig d0 */
-        addl    %sp@+,%sp               /* stk adj */
-        addql   #8,%sp                  /* remove exception */
-        movel   %sp,sw_ksp              /* save ksp */
-        subql   #8,sw_usp               /* set exception */
-        movel   sw_usp,%sp              /* restore usp */
-        rte
+        RESTORE_USER
 
 Lwork_to_do:
         movel   %a0@(TI_FLAGS),%d1      /* get thread_info->flags */
@@ -201,9 +192,8 @@ ENTRY(inthandler)
  */
 ENTRY(resume)
         movel   %a0, %d1                        /* get prev thread in d1 */
-
-        movel   sw_usp,%d0                      /* save usp */
-        movel   %d0,%a0@(TASK_THREAD+THREAD_USP)
+        RDUSP
+        movel   %a2,%a0@(TASK_THREAD+THREAD_USP)
 
         SAVE_SWITCH_STACK
         movel   %sp,%a0@(TASK_THREAD+THREAD_KSP) /* save kernel stack pointer */
@@ -211,5 +201,5 @@ ENTRY(resume)
         RESTORE_SWITCH_STACK
 
         movel   %a1@(TASK_THREAD+THREAD_USP),%a0 /* restore thread user stack */
-        movel   %a0, sw_usp
+        WRUSP
         rts