[PATCH] sparc: Fix context switch on SMP

[Sebastian Huber]

We must not load registers (e.g. PSR) from the heir context area before
the heir stopped execution.  Bug reported by Daniel Cederman.
---
 c/src/lib/libbsp/sparc/shared/irq_asm.S | 32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/c/src/lib/libbsp/sparc/shared/irq_asm.S b/c/src/lib/libbsp/sparc/shared/irq_asm.S
index 9d8600e..d6c0ee6 100644
--- a/c/src/lib/libbsp/sparc/shared/irq_asm.S
+++ b/c/src/lib/libbsp/sparc/shared/irq_asm.S
@@ -91,6 +91,22 @@ SYM(_CPU_Context_switch):
 
         PUBLIC(_CPU_Context_restore_heir)
 SYM(_CPU_Context_restore_heir):
+#if defined(RTEMS_SMP)
+        ! The executing context no longer executes on this processor
+        st      %g0, [%o0 + SPARC_CONTEXT_CONTROL_IS_EXECUTING_OFFSET]
+
+        ! Try to update the is executing indicator of the heir context
+        mov     1, %g1
+
+try_update_is_executing:
+
+        swap    [%o1 + SPARC_CONTEXT_CONTROL_IS_EXECUTING_OFFSET], %g1
+        cmp     %g1, 0
+        bne     check_is_executing
+
+        ! The next load is in a delay slot, which is all right
+#endif
+
         /*
          *  Flush all windows with valid contents except the current one.
          *  In examining the set register windows, one may logically divide
@@ -186,22 +202,6 @@ done_flushing:
         nop
         nop
 
-#if defined(RTEMS_SMP)
-        ! The executing context no longer executes on this processor
-        st      %g0, [%o0 + SPARC_CONTEXT_CONTROL_IS_EXECUTING_OFFSET]
-
-        ! Try to update the is executing indicator of the heir context
-        mov     1, %g1
-
-try_update_is_executing:
-
-        swap    [%o1 + SPARC_CONTEXT_CONTROL_IS_EXECUTING_OFFSET], %g1
-        cmp     %g1, 0
-        bne     check_is_executing
-
-        ! The next load is in a delay slot, which is all right
-#endif
-
         ld      [%o1 + G5_OFFSET], %g5        ! restore the global registers
         ld      [%o1 + G7_OFFSET], %g7
 
-- 
1.8.4.5