SH: Move address environment switch from the task switchers to the interrupt handler. That may save doing the action multiple times per interrupt

arch/sh/src/common/up_blocktask.c

@@ -49,7 +49,7 @@
 #include "up_internal.h"
 
 /****************************************************************************
- * Private Definitions
+ * Pre-processor Definitions
  ****************************************************************************/
 
 /****************************************************************************
@@ -136,19 +136,11 @@ void up_block_task(struct tcb_s *tcb, tstate_t task_state)
 
           rtcb = (struct tcb_s*)g_readytorun.head;
 
-          /* Then switch contexts */
+          /* Then switch contexts.  Any necessary address environment
-
+           * changes will be made when the interrupt returns.
-          current_regs = rtcb->xcp.regs;
-
-#ifdef CONFIG_ARCH_ADDRENV
-         /* Make sure that the address environment for the previously
-          * running task is closed down gracefully (data caches dump,
-          * MMU flushed) and set up the address environment for the new
-          * thread at the head of the ready-to-run list.
            */
 
-         (void)group_addrenv(rtcb);
+          current_regs = rtcb->xcp.regs;
-#endif
         }
 
       /* Copy the user C context into the TCB at the (old) head of the

arch/sh/src/common/up_doirq.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/sh/src/common/up_doirq.c
  *
- *   Copyright (C) 2008-2009, 2011 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2008-2009, 2011, 2014 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -48,8 +48,10 @@
 #include "up_arch.h"
 #include "up_internal.h"
 
+#include "group/group.h"
+
 /****************************************************************************
- * Definitions
+ * Pre-processor Definitions
  ****************************************************************************/
 
 /****************************************************************************
@@ -76,23 +78,14 @@ uint32_t *up_doirq(int irq, uint32_t* regs)
 #else
   if ((unsigned)irq < NR_IRQS)
     {
-       uint32_t *savestate;
-
-       /* Nested interrupts are not supported in this implementation.  If
-        * you want to implement nested interrupts, you would have to (1)
-        * change the way that current_regs is handled and (2) the design
-        * associated with CONFIG_ARCH_INTERRUPTSTACK.  The savestate
-        * variable will not work for that purpose as implemented here
-        * because only the outermost nested interrupt can result in a
-        * context switch (it can probably be deleted).
-        */
-
       /* Current regs non-zero indicates that we are processing
        * an interrupt; current_regs is also used to manage
        * interrupt level context switches.
+       *
+       * Nested interrupts are not supported.
        */
 
-       savestate    = (uint32_t*)current_regs;
+      DEBUGASSERT(current_regs == NULL);
       current_regs = regs;
 
       /* Mask and acknowledge the interrupt (if supported by the chip) */
@@ -105,18 +98,44 @@ uint32_t *up_doirq(int irq, uint32_t* regs)
 
       irq_dispatch(irq, regs);
 
+#if defined(CONFIG_ARCH_FPU) || defined(CONFIG_ARCH_ADDRENV)
+      /* Check for a context switch.  If a context switch occurred, then
+       * current_regs will have a different value than it did on entry.  If an
+       * interrupt level context switch has occurred, then restore the floating
+       * point state and the establish the correct address environment before
+       * returning from the interrupt.
+       */
+
+      if (regs != current_regs)
+        {
+#ifdef CONFIG_ARCH_FPU
+          /* Restore floating point registers */
+
+          up_restorefpu((uint32_t*)current_regs);
+#endif
+
+#ifdef CONFIG_ARCH_ADDRENV
+          /* Make sure that the address environment for the previously
+           * running task is closed down gracefully (data caches dump,
+           * MMU flushed) and set up the address environment for the new
+           * thread at the head of the ready-to-run list.
+           */
+
+          (void)group_addrenv(rtcb);
+#endif
+        }
+#endif
       /* Get the current value of regs... it may have changed because
        * of a context switch performed during interrupt processing.
        */
 
       regs = current_regs;
 
-       /* Restore the previous value of current_regs.  NULL would indicate that
+      /* Set current_regs to NULL to indicate that we are no longer in an
-        * we are no longer in an interrupt handler.  It will be non-NULL if we
+       * interrupt handler.
-        * are returning from a nested interrupt.
        */
 
-       current_regs = savestate;
+      current_regs = NULL;
 
       /* Unmask the last interrupt (global interrupts are still
        * disabled.
@@ -126,6 +145,7 @@ uint32_t *up_doirq(int irq, uint32_t* regs)
       up_enable_irq(irq);
 #endif
     }
+
   board_led_off(LED_INIRQ);
 #endif
   return regs;

arch/sh/src/common/up_unblocktask.c

@@ -49,7 +49,7 @@
 #include "up_internal.h"
 
 /****************************************************************************
- * Private Definitions
+ * Pre-processor Definitions
  ****************************************************************************/
 
 /****************************************************************************
@@ -127,19 +127,11 @@ void up_unblock_task(struct tcb_s *tcb)
 
           rtcb = (struct tcb_s*)g_readytorun.head;
 
-          /* Then switch contexts */
+          /* Then switch contexts.  Any necessary address environment
-
+           * changes will be made when the interrupt returns.
-          current_regs = rtcb->xcp.regs;
-
-#ifdef CONFIG_ARCH_ADDRENV
-         /* Make sure that the address environment for the previously
-          * running task is closed down gracefully (data caches dump,
-          * MMU flushed) and set up the address environment for the new
-          * thread at the head of the ready-to-run list.
            */
 
-         (void)group_addrenv(rtcb);
+          current_regs = rtcb->xcp.regs;
-#endif
         }
 
       /* We are not in an interrupt handler.  Copy the user C context