Implement MicroBlazeV9 stack protection (#523)

* Implement stack protection for MicroBlaze (without MPU wrappers)

portable/GCC/MicroBlazeV9/port.c

@@ -105,7 +105,11 @@ static XIntc xInterruptControllerInstance;
  *
  * See the portable.h header file.
  */
+#if ( portHAS_STACK_OVERFLOW_CHECKING == 1 )
+StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, StackType_t *pxEndOfStack, TaskFunction_t pxCode, void *pvParameters )
+#else
 StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
+#endif
 {
 extern void *_SDA2_BASE_, *_SDA_BASE_;
 const uint32_t ulR2 = ( uint32_t ) &_SDA2_BASE_;
@@ -122,6 +126,14 @@ extern void _start1( void );
 	*pxTopOfStack = ( StackType_t ) 0x00000000;
 	pxTopOfStack--;
 
+	#if ( portHAS_STACK_OVERFLOW_CHECKING == 1 )
+		/* Store the stack limits. */
+		*pxTopOfStack = (StackType_t) (pxTopOfStack + 3);
+		pxTopOfStack--;
+		*pxTopOfStack = (StackType_t) pxEndOfStack;
+		pxTopOfStack--;
+	#endif
+
 	#if( XPAR_MICROBLAZE_USE_FPU != 0 )
 		/* The FSR value placed in the initial task context is just 0. */
 		*pxTopOfStack = portINITIAL_FSR;

portable/GCC/MicroBlazeV9/portasm.S

@@ -33,16 +33,6 @@
 #include "microblaze_exceptions_g.h"
 #include "xparameters.h"
 
-/* The context is oversized to allow functions called from the ISR to write
-back into the caller stack. */
-#if( XPAR_MICROBLAZE_USE_FPU != 0 )
-	#define portCONTEXT_SIZE 136
-	#define portMINUS_CONTEXT_SIZE -136
-#else
-	#define portCONTEXT_SIZE 132
-	#define portMINUS_CONTEXT_SIZE -132
-#endif
-
 /* Offsets from the stack pointer at which saved registers are placed. */
 #define portR31_OFFSET	4
 #define portR30_OFFSET	8
@@ -76,7 +66,31 @@ back into the caller stack. */
 #define portR2_OFFSET	120
 #define portCRITICAL_NESTING_OFFSET 124
 #define portMSR_OFFSET 128
-#define portFSR_OFFSET 132
+
+#if( XPAR_MICROBLAZE_USE_FPU != 0 )
+	#define portFSR_OFFSET 132
+	#if( XPAR_MICROBLAZE_USE_STACK_PROTECTION )
+		#define portSLR_OFFSET 136
+		#define portSHR_OFFSET 140
+
+		#define portCONTEXT_SIZE 144
+		#define portMINUS_CONTEXT_SIZE -144
+	#else
+		#define portCONTEXT_SIZE 136
+		#define portMINUS_CONTEXT_SIZE -136
+	#endif
+#else
+	#if( XPAR_MICROBLAZE_USE_STACK_PROTECTION )
+		#define portSLR_OFFSET 132
+		#define portSHR_OFFSET 136
+
+		#define portCONTEXT_SIZE 140
+		#define portMINUS_CONTEXT_SIZE -140
+	#else
+		#define portCONTEXT_SIZE 132
+		#define portMINUS_CONTEXT_SIZE -132
+	#endif
+#endif
 
 	.extern pxCurrentTCB
 	.extern XIntc_DeviceInterruptHandler
@@ -144,6 +158,14 @@ back into the caller stack. */
 		swi r18, r1, portFSR_OFFSET
 	#endif
 
+#if( XPAR_MICROBLAZE_USE_STACK_PROTECTION )
+	/* Save the stack limits */
+	mfs r18, rslr
+	swi r18, r1, portSLR_OFFSET
+	mfs r18, rshr
+	swi r18, r1, portSHR_OFFSET
+#endif
+
 	/* Save the top of stack value to the TCB. */
 	lwi r3, r0, pxCurrentTCB
 	sw	r1, r0, r3
@@ -156,6 +178,17 @@ back into the caller stack. */
 	lwi r18, r0, pxCurrentTCB
 	lw	r1, r0, r18
 
+#if( XPAR_MICROBLAZE_USE_STACK_PROTECTION )
+	/* Restore the stack limits -- must not load from r1 (Stack Pointer)
+	because if the address of load or store instruction is out of range,
+	it will trigger Stack Protection Violation exception. */
+	or	r18, r0, r1
+	lwi	r12, r18, portSLR_OFFSET
+	mts	rslr, r12
+	lwi	r12, r18, portSHR_OFFSET
+	mts	rshr, r12
+#endif
+
 	/* Restore the general registers. */
 	lwi r31, r1, portR31_OFFSET
 	lwi r30, r1, portR30_OFFSET
@@ -252,6 +285,13 @@ _interrupt_handler:
 	/* Switch to the ISR stack. */
 	lwi r1, r0, pulISRStack
 
+#if( XPAR_MICROBLAZE_USE_STACK_PROTECTION )
+	ori r18, r0, _stack_end
+	mts rslr, r18
+	ori r18, r0, _stack
+	mts rshr, r18
+#endif
+
 	/* The parameter to the interrupt handler. */
 	ori r5, r0, configINTERRUPT_CONTROLLER_TO_USE
 
@@ -296,6 +336,13 @@ VPortYieldASM:
 	/* Switch to use the ISR stack. */
 	lwi r1, r0, pulISRStack
 
+#if( XPAR_MICROBLAZE_USE_STACK_PROTECTION )
+	ori r18, r0, _stack_end
+	mts rslr, r18
+	ori r18, r0, _stack
+	mts rshr, r18
+#endif
+
 	/* Select the next task to execute. */
 	bralid r15, vTaskSwitchContext
 	or r0, r0, r0

portable/GCC/MicroBlazeV9/portmacro.h

@@ -152,6 +152,11 @@ extern volatile uint32_t ulTaskSwitchRequested;
 #define portNOP()					asm volatile ( "NOP" )
 /*-----------------------------------------------------------*/
 
+#if( XPAR_MICROBLAZE_USE_STACK_PROTECTION )
+#define portHAS_STACK_OVERFLOW_CHECKING	1
+#endif
+/*-----------------------------------------------------------*/
+
 /* Task function macros as described on the FreeRTOS.org WEB site. */
 #define portTASK_FUNCTION_PROTO( vFunction, pvParameters ) void vFunction( void *pvParameters )
 #define portTASK_FUNCTION( vFunction, pvParameters ) void vFunction( void *pvParameters )