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

arch/arm/src/arm/up_blocktask.c

@@ -137,19 +137,11 @@ 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.
-          up_restorestate(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);
+          up_restorestate(rtcb->xcp.regs);
-#endif
         }
 
       /* Copy the user C context into the TCB at the (old) head of the

arch/arm/src/arm/up_doirq.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/arm/src/arm/up_doirq.c
  *
- *   Copyright (C) 2007-2009, 2011, 2013 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2011, 2013-2014 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -49,6 +49,8 @@
 #include "up_arch.h"
 #include "up_internal.h"
 
+#include "group/group.h"
+
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -75,21 +77,14 @@ void up_doirq(int irq, uint32_t *regs)
 #ifdef CONFIG_SUPPRESS_INTERRUPTS
   PANIC();
 #else
-  uint32_t *savestate;
+  /* Nested interrupts are not supported */
 
-  /* Nested interrupts are not supported in this implementation.  If you want
+  DEBUGASSERT(current_regs == NULL);
-   * to implement nested interrupts, you would have to (1) change the way that
-   * current_regs is handled and (2) implement design changes 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.
    */
 
-  savestate    = (uint32_t*)current_regs;
   current_regs = regs;
 
   /* Mask and acknowledge the interrupt */
@@ -100,12 +95,39 @@ void up_doirq(int irq, uint32_t *regs)
 
   irq_dispatch(irq, regs);
 
-  /* Restore the previous value of current_regs.  NULL would indicate that
+  /* Check for a context switch.  If a context switch occurred, then
-   * we are no longer in an interrupt handler.  It will be non-NULL if we
+   * current_regs will have a different value than it did on entry.  If an
-   * are returning from a nested interrupt.
+   * interrupt level context switch has occurred, then restore the floating
+   * point state and the establish the correct address environment before
+   * returning from the interrupt.
    */
 
-  current_regs = savestate;
+#if defined(CONFIG_ARCH_FPU) || defined(CONFIG_ARCH_ADDRENV)
+  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
+
+  /* Set current_regs to NULL to indicate that we are no longer in an
+   * interrupt handler.
+   */
+
+  current_regs = NULL;
 
   /* Unmask the last interrupt (global interrupts are still disabled) */
 

arch/arm/src/arm/up_unblocktask.c

@@ -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.
-          up_restorestate(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);
+          up_restorestate(rtcb->xcp.regs);
-#endif
         }
 
       /* We are not in an interrupt handler.  Copy the user C context

arch/arm/src/armv7-a/arm_blocktask.c

@@ -137,19 +137,11 @@ 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.
-          up_restorestate(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);
+          up_restorestate(rtcb->xcp.regs);
-#endif
         }
 
       /* Copy the user C context into the TCB at the (old) head of the

arch/arm/src/armv7-a/arm_doirq.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/arm/src/armv7-a/arm_doirq.c
  *
- *   Copyright (C) 2013 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2013-2014 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -49,6 +49,8 @@
 #include "up_arch.h"
 #include "up_internal.h"
 
+#include "group/group.h"
+
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -93,18 +95,31 @@ uint32_t *arm_doirq(int irq, uint32_t *regs)
 
   irq_dispatch(irq, regs);
 
-  /* Check for a context switch.  If a context switch occured, then
+  /* 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 before returning from the interrupt.
+   * point state and the establish the correct address environment before
+   * returning from the interrupt.
    */
 
-#ifdef CONFIG_ARCH_FPU
+#if defined(CONFIG_ARCH_FPU) || defined(CONFIG_ARCH_ADDRENV)
   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
 

arch/arm/src/armv7-a/arm_unblocktask.c

@@ -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.
-          up_restorestate(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);
+          up_restorestate(rtcb->xcp.regs);
-#endif
         }
 
       /* We are not in an interrupt handler.  Copy the user C context