Add portTASK_SWITCH_HOOK (#867)

This commit adds a portTASK_SWITCH_HOOK() macro which allows ports to inject
behavior immediately after a context switch. For example, this macro could be
used by ports that need to set an end of stack watchpoint after a context
swtich.

Co-authored-by: Rahul Kar <118818625+kar-rahul-aws@users.noreply.github.com>
Co-authored-by: Soren Ptak <ptaksoren@gmail.com>
Co-authored-by: chinglee-iot <61685396+chinglee-iot@users.noreply.github.com>
Co-authored-by: Tony Josi <tonyjosi@amazon.com>
Co-authored-by: Gaurav-Aggarwal-AWS <33462878+aggarg@users.noreply.github.com>

include/FreeRTOS.h

@@ -529,6 +529,10 @@
     #define portSETUP_TCB( pxTCB )    ( void ) ( pxTCB )
 #endif
 
+#ifndef portTASK_SWITCH_HOOK
+    #define portTASK_SWITCH_HOOK( pxTCB )    ( void ) ( pxTCB )
+#endif
+
 #ifndef configQUEUE_REGISTRY_SIZE
     #define configQUEUE_REGISTRY_SIZE    0U
 #endif

tasks.c

@@ -5153,6 +5153,11 @@ BaseType_t xTaskIncrementTick( void )
             taskSELECT_HIGHEST_PRIORITY_TASK();
             traceTASK_SWITCHED_IN();
 
+            /* Macro to inject port specific behaviour immediately after
+             * switching tasks, such as setting an end of stack watchpoint
+             * or reconfiguring the MPU. */
+            portTASK_SWITCH_HOOK( pxCurrentTCB );
+
             /* After the new task is switched in, update the global errno. */
             #if ( configUSE_POSIX_ERRNO == 1 )
             {
@@ -5245,6 +5250,11 @@ BaseType_t xTaskIncrementTick( void )
                 taskSELECT_HIGHEST_PRIORITY_TASK( xCoreID );
                 traceTASK_SWITCHED_IN();
 
+                /* Macro to inject port specific behaviour immediately after
+                 * switching tasks, such as setting an end of stack watchpoint
+                 * or reconfiguring the MPU. */
+                portTASK_SWITCH_HOOK( pxCurrentTCBs[ portGET_CORE_ID() ] );
+
                 /* After the new task is switched in, update the global errno. */
                 #if ( configUSE_POSIX_ERRNO == 1 )
                 {