Simplify the assert that checks if a non-ISR safe function is called from an ISR in the GCC Cortex-A9 port.

FreeRTOS/Source/portable/GCC/ARM_CA9/port.c

@@ -110,10 +110,6 @@
 	#error configMAX_API_CALL_INTERRUPT_PRIORITY must be greater than ( configUNIQUE_INTERRUPT_PRIORITIES / 2 )
 #endif
 
-/* Used to check non ISR safe API functions are not called from inside an
-ISR. */
-#define portASSERT_IF_IN_INTERRUPT() configASSERT( ( portICCRPR_RUNNING_PRIORITY_REGISTER == 0xffUL ) || ( portICCRPR_RUNNING_PRIORITY_REGISTER == portLOWEST_INTERRUPT_PRIORITY ) )
-
 /* Some vendor specific files default configCLEAR_TICK_INTERRUPT() in
 portmacro.h. */
 #ifndef configCLEAR_TICK_INTERRUPT
@@ -375,10 +371,6 @@ void vPortEndScheduler( void )
 
 void vPortEnterCritical( void )
 {
-	/* This is not the interrupt safe version of the enter critical function.
-	Only API functions that end in "FromISR" can be used in an interrupt. */
-	portASSERT_IF_IN_INTERRUPT();
-
 	/* Mask interrupts up to the max syscall interrupt priority. */
 	ulPortSetInterruptMask();
 
@@ -386,15 +378,20 @@ void vPortEnterCritical( void )
 	directly.  Increment ulCriticalNesting to keep a count of how many times
 	portENTER_CRITICAL() has been called. */
 	ulCriticalNesting++;
+
+	/* This is not the interrupt safe version of the enter critical function.
+	Only API functions that end in "FromISR" can be used in an interrupt.  The
+	test of ulCriticalNesting() guards against recursive calls to assert in the
+	case that assert itself contains a call to taskENTER_CRITICAL. */
+	if( ulCriticalNesting == 1 )
+	{
+		configASSERT( ulPortInterruptNesting == 0 );
+	}
 }
 /*-----------------------------------------------------------*/
 
 void vPortExitCritical( void )
 {
-	/* This is not the interrupt safe version of the enter critical function.
-	Only API functions that end in "FromISR" can be used in an interrupt. */
-	portASSERT_IF_IN_INTERRUPT();
-
 	if( ulCriticalNesting > portNO_CRITICAL_NESTING )
 	{
 		/* Decrement the nesting count as the critical section is being