Add Cortex-A53 port with system register interface for CPU interface access (#357)

The difference between this port and portable/GCC/ARM_CA53_64_BIT is
that this port uses System Register interface to access CPU interface
while the other one uses Memory-mapped interface.

Signed-off-by: Gaurav Aggarwal 
Co-authored-by: Cobus van Eeden <35851496+cobusve@users.noreply.github.com>
diff --git a/portable/GCC/ARM_CA53_64_BIT_SRE/port.c b/portable/GCC/ARM_CA53_64_BIT_SRE/port.c
new file mode 100644
index 0000000..475916f
--- /dev/null
+++ b/portable/GCC/ARM_CA53_64_BIT_SRE/port.c
@@ -0,0 +1,459 @@
+/*
+ * FreeRTOS Kernel <DEVELOPMENT BRANCH>
+ * Copyright (C) 2021 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * https://www.FreeRTOS.org
+ * https://github.com/FreeRTOS
+ *
+ */
+
+/* Standard includes. */
+#include <stdlib.h>
+
+/* Scheduler includes. */
+#include "FreeRTOS.h"
+#include "task.h"
+
+#ifndef configUNIQUE_INTERRUPT_PRIORITIES
+	#error configUNIQUE_INTERRUPT_PRIORITIES must be defined.  See https://www.FreeRTOS.org/Using-FreeRTOS-on-Cortex-A-Embedded-Processors.html
+#endif
+
+#ifndef configSETUP_TICK_INTERRUPT
+	#error configSETUP_TICK_INTERRUPT() must be defined.  See https://www.FreeRTOS.org/Using-FreeRTOS-on-Cortex-A-Embedded-Processors.html
+#endif /* configSETUP_TICK_INTERRUPT */
+
+#ifndef configMAX_API_CALL_INTERRUPT_PRIORITY
+	#error configMAX_API_CALL_INTERRUPT_PRIORITY must be defined.  See https://www.FreeRTOS.org/Using-FreeRTOS-on-Cortex-A-Embedded-Processors.html
+#endif
+
+#if configMAX_API_CALL_INTERRUPT_PRIORITY == 0
+	#error configMAX_API_CALL_INTERRUPT_PRIORITY must not be set to 0
+#endif
+
+#if configMAX_API_CALL_INTERRUPT_PRIORITY > configUNIQUE_INTERRUPT_PRIORITIES
+	#error configMAX_API_CALL_INTERRUPT_PRIORITY must be less than or equal to configUNIQUE_INTERRUPT_PRIORITIES as the lower the numeric priority value the higher the logical interrupt priority
+#endif
+
+#if configUSE_PORT_OPTIMISED_TASK_SELECTION == 1
+	/* Check the configuration. */
+	#if( configMAX_PRIORITIES > 32 )
+		#error configUSE_PORT_OPTIMISED_TASK_SELECTION can only be set to 1 when configMAX_PRIORITIES is less than or equal to 32.  It is very rare that a system requires more than 10 to 15 difference priorities as tasks that share a priority will time slice.
+	#endif
+#endif /* configUSE_PORT_OPTIMISED_TASK_SELECTION */
+
+/* In case security extensions are implemented. */
+#if configMAX_API_CALL_INTERRUPT_PRIORITY <= ( configUNIQUE_INTERRUPT_PRIORITIES / 2 )
+	#error configMAX_API_CALL_INTERRUPT_PRIORITY must be greater than ( configUNIQUE_INTERRUPT_PRIORITIES / 2 )
+#endif
+
+/* Some vendor specific files default configCLEAR_TICK_INTERRUPT() in
+portmacro.h. */
+#ifndef configCLEAR_TICK_INTERRUPT
+	#define configCLEAR_TICK_INTERRUPT()
+#endif
+
+/* A critical section is exited when the critical section nesting count reaches
+this value. */
+#define portNO_CRITICAL_NESTING			( ( size_t ) 0 )
+
+/* In all GICs 255 can be written to the priority mask register to unmask all
+(but the lowest) interrupt priority. */
+#define portUNMASK_VALUE				( 0xFFUL )
+
+/* Tasks are not created with a floating point context, but can be given a
+floating point context after they have been created.  A variable is stored as
+part of the tasks context that holds portNO_FLOATING_POINT_CONTEXT if the task
+does not have an FPU context, or any other value if the task does have an FPU
+context. */
+#define portNO_FLOATING_POINT_CONTEXT	( ( StackType_t ) 0 )
+
+/* Constants required to setup the initial task context. */
+#define portSP_ELx						( ( StackType_t ) 0x01 )
+#define portSP_EL0						( ( StackType_t ) 0x00 )
+
+#if defined( GUEST )
+	#define portEL1						( ( StackType_t ) 0x04 )
+	#define portINITIAL_PSTATE				( portEL1 | portSP_EL0 )
+#else
+	#define portEL3						( ( StackType_t ) 0x0c )
+	/* At the time of writing, the BSP only supports EL3. */
+	#define portINITIAL_PSTATE			( portEL3 | portSP_EL0 )
+#endif
+
+/* Masks all bits in the APSR other than the mode bits. */
+#define portAPSR_MODE_BITS_MASK			( 0x0C )
+
+/* The I bit in the DAIF bits. */
+#define portDAIF_I						( 0x80 )
+
+/* Macro to unmask all interrupt priorities. */
+/* s3_0_c4_c6_0 is ICC_PMR_EL1. */
+#define portCLEAR_INTERRUPT_MASK()						\
+{														\
+	__asm volatile (	"MSR DAIFSET, #2 		\n"		\
+						"DSB SY					\n"		\
+						"ISB SY					\n"		\
+						"MSR s3_0_c4_c6_0, %0 	\n"		\
+						"DSB SY					\n"		\
+						"ISB SY					\n"		\
+						"MSR DAIFCLR, #2 		\n"		\
+						"DSB SY					\n"		\
+						"ISB SY					\n"		\
+						::"r"( portUNMASK_VALUE ) );	\
+}
+
+/*-----------------------------------------------------------*/
+
+/*
+ * Starts the first task executing.  This function is necessarily written in
+ * assembly code so is implemented in portASM.s.
+ */
+extern void vPortRestoreTaskContext( void );
+
+/*-----------------------------------------------------------*/
+
+/* A variable is used to keep track of the critical section nesting.  This
+variable has to be stored as part of the task context and must be initialised to
+a non zero value to ensure interrupts don't inadvertently become unmasked before
+the scheduler starts.  As it is stored as part of the task context it will
+automatically be set to 0 when the first task is started. */
+volatile uint64_t ullCriticalNesting = 9999ULL;
+
+/* Saved as part of the task context.  If ullPortTaskHasFPUContext is non-zero
+then floating point context must be saved and restored for the task. */
+uint64_t ullPortTaskHasFPUContext = pdFALSE;
+
+/* Set to 1 to pend a context switch from an ISR. */
+uint64_t ullPortYieldRequired = pdFALSE;
+
+/* Counts the interrupt nesting depth.  A context switch is only performed if
+if the nesting depth is 0. */
+uint64_t ullPortInterruptNesting = 0;
+
+/* Used in the ASM code. */
+__attribute__(( used )) const uint64_t ullMaxAPIPriorityMask = ( configMAX_API_CALL_INTERRUPT_PRIORITY << portPRIORITY_SHIFT );
+
+/*-----------------------------------------------------------*/
+
+/*
+ * See header file for description.
+ */
+StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
+{
+	/* Setup the initial stack of the task.  The stack is set exactly as
+	expected by the portRESTORE_CONTEXT() macro. */
+
+	/* First all the general purpose registers. */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x0101010101010101ULL;	/* R1 */
+	pxTopOfStack--;
+	*pxTopOfStack = ( StackType_t ) pvParameters; /* R0 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x0303030303030303ULL;	/* R3 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x0202020202020202ULL;	/* R2 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x0505050505050505ULL;	/* R5 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x0404040404040404ULL;	/* R4 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x0707070707070707ULL;	/* R7 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x0606060606060606ULL;	/* R6 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x0909090909090909ULL;	/* R9 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x0808080808080808ULL;	/* R8 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x1111111111111111ULL;	/* R11 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x1010101010101010ULL;	/* R10 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x1313131313131313ULL;	/* R13 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x1212121212121212ULL;	/* R12 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x1515151515151515ULL;	/* R15 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x1414141414141414ULL;	/* R14 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x1717171717171717ULL;	/* R17 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x1616161616161616ULL;	/* R16 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x1919191919191919ULL;	/* R19 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x1818181818181818ULL;	/* R18 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x2121212121212121ULL;	/* R21 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x2020202020202020ULL;	/* R20 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x2323232323232323ULL;	/* R23 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x2222222222222222ULL;	/* R22 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x2525252525252525ULL;	/* R25 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x2424242424242424ULL;	/* R24 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x2727272727272727ULL;	/* R27 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x2626262626262626ULL;	/* R26 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x2929292929292929ULL;	/* R29 */
+	pxTopOfStack--;
+	*pxTopOfStack = 0x2828282828282828ULL;	/* R28 */
+	pxTopOfStack--;
+	*pxTopOfStack = ( StackType_t ) 0x00;	/* XZR - has no effect, used so there are an even number of registers. */
+	pxTopOfStack--;
+	*pxTopOfStack = ( StackType_t ) 0x00;	/* R30 - procedure call link register. */
+	pxTopOfStack--;
+
+	*pxTopOfStack = portINITIAL_PSTATE;
+	pxTopOfStack--;
+
+	*pxTopOfStack = ( StackType_t ) pxCode; /* Exception return address. */
+	pxTopOfStack--;
+
+	/* The task will start with a critical nesting count of 0 as interrupts are
+	enabled. */
+	*pxTopOfStack = portNO_CRITICAL_NESTING;
+	pxTopOfStack--;
+
+	/* The task will start without a floating point context.  A task that uses
+	the floating point hardware must call vPortTaskUsesFPU() before executing
+	any floating point instructions. */
+	*pxTopOfStack = portNO_FLOATING_POINT_CONTEXT;
+
+	return pxTopOfStack;
+}
+/*-----------------------------------------------------------*/
+
+BaseType_t xPortStartScheduler( void )
+{
+uint32_t ulAPSR;
+
+	__asm volatile ( "MRS %0, CurrentEL" : "=r" ( ulAPSR ) );
+	ulAPSR &= portAPSR_MODE_BITS_MASK;
+
+#if defined( GUEST )
+	configASSERT( ulAPSR == portEL1 );
+	if( ulAPSR == portEL1 )
+#else
+	configASSERT( ulAPSR == portEL3 );
+	if( ulAPSR == portEL3 )
+#endif
+	{
+		/* Interrupts are turned off in the CPU itself to ensure a tick does
+		not execute	while the scheduler is being started.  Interrupts are
+		automatically turned back on in the CPU when the first task starts
+		executing. */
+		portDISABLE_INTERRUPTS();
+
+		/* Start the timer that generates the tick ISR. */
+		configSETUP_TICK_INTERRUPT();
+
+		/* Start the first task executing. */
+		vPortRestoreTaskContext();
+	}
+
+	return 0;
+}
+/*-----------------------------------------------------------*/
+
+void vPortEndScheduler( void )
+{
+	/* Not implemented in ports where there is nothing to return to.
+	Artificially force an assert. */
+	configASSERT( ullCriticalNesting == 1000ULL );
+}
+/*-----------------------------------------------------------*/
+
+void vPortEnterCritical( void )
+{
+	/* Mask interrupts up to the max syscall interrupt priority. */
+	uxPortSetInterruptMask();
+
+	/* Now interrupts are disabled ullCriticalNesting can be accessed
+	directly.  Increment ullCriticalNesting to keep a count of how many times
+	portENTER_CRITICAL() has been called. */
+	ullCriticalNesting++;
+
+	/* This is not the interrupt safe version of the enter critical function so
+	assert() if it is being called from an interrupt context.  Only API
+	functions that end in "FromISR" can be used in an interrupt.  Only assert if
+	the critical nesting count is 1 to protect against recursive calls if the
+	assert function also uses a critical section. */
+	if( ullCriticalNesting == 1ULL )
+	{
+		configASSERT( ullPortInterruptNesting == 0 );
+	}
+}
+/*-----------------------------------------------------------*/
+
+void vPortExitCritical( void )
+{
+	if( ullCriticalNesting > portNO_CRITICAL_NESTING )
+	{
+		/* Decrement the nesting count as the critical section is being
+		exited. */
+		ullCriticalNesting--;
+
+		/* If the nesting level has reached zero then all interrupt
+		priorities must be re-enabled. */
+		if( ullCriticalNesting == portNO_CRITICAL_NESTING )
+		{
+			/* Critical nesting has reached zero so all interrupt priorities
+			should be unmasked. */
+			portCLEAR_INTERRUPT_MASK();
+		}
+	}
+}
+/*-----------------------------------------------------------*/
+
+void FreeRTOS_Tick_Handler( void )
+{
+	/* Must be the lowest possible priority. */
+	#if !defined( QEMU )
+	{
+		uint64_t ullRunningInterruptPriority;
+		/* s3_0_c12_c11_3 is ICC_RPR_EL1. */
+		__asm volatile ( "MRS %0, s3_0_c12_c11_3" : "=r" ( ullRunningInterruptPriority ) );
+		configASSERT( ullRunningInterruptPriority == ( portLOWEST_USABLE_INTERRUPT_PRIORITY << portPRIORITY_SHIFT ) );
+	}
+	#endif
+
+	/* Interrupts should not be enabled before this point. */
+	#if( configASSERT_DEFINED == 1 )
+	{
+		uint32_t ulMaskBits;
+
+		__asm volatile( "MRS %0, DAIF" : "=r"( ulMaskBits ) :: "memory" );
+		configASSERT( ( ulMaskBits & portDAIF_I ) != 0 );
+	}
+	#endif /* configASSERT_DEFINED */
+
+	/* Set interrupt mask before altering scheduler structures.   The tick
+	handler runs at the lowest priority, so interrupts cannot already be masked,
+	so there is no need to save and restore the current mask value.  It is
+	necessary to turn off interrupts in the CPU itself while the ICCPMR is being
+	updated. */
+	/* s3_0_c4_c6_0 is ICC_PMR_EL1. */
+	__asm volatile ( "MSR s3_0_c4_c6_0, %0		\n"
+					 "DSB SY					\n"
+					 "ISB SY					\n"
+					 :: "r" ( configMAX_API_CALL_INTERRUPT_PRIORITY << portPRIORITY_SHIFT ) : "memory" );
+
+	/* Ok to enable interrupts after the interrupt source has been cleared. */
+	configCLEAR_TICK_INTERRUPT();
+	portENABLE_INTERRUPTS();
+
+	/* Increment the RTOS tick. */
+	if( xTaskIncrementTick() != pdFALSE )
+	{
+		ullPortYieldRequired = pdTRUE;
+	}
+
+	/* Ensure all interrupt priorities are active again. */
+	portCLEAR_INTERRUPT_MASK();
+}
+/*-----------------------------------------------------------*/
+
+void vPortTaskUsesFPU( void )
+{
+	/* A task is registering the fact that it needs an FPU context.  Set the
+	FPU flag (which is saved as part of the task context). */
+	ullPortTaskHasFPUContext = pdTRUE;
+
+	/* Consider initialising the FPSR here - but probably not necessary in
+	AArch64. */
+}
+/*-----------------------------------------------------------*/
+
+void vPortClearInterruptMask( UBaseType_t uxNewMaskValue )
+{
+	if( uxNewMaskValue == pdFALSE )
+	{
+		portCLEAR_INTERRUPT_MASK();
+	}
+}
+/*-----------------------------------------------------------*/
+
+UBaseType_t uxPortSetInterruptMask( void )
+{
+uint32_t ulReturn;
+uint64_t ullPMRValue;
+
+	/* Interrupt in the CPU must be turned off while the ICCPMR is being
+	updated. */
+	portDISABLE_INTERRUPTS();
+	/* s3_0_c4_c6_0 is ICC_PMR_EL1. */
+	__asm volatile ( "MRS %0, s3_0_c4_c6_0" : "=r" ( ullPMRValue ) );
+	if( ullPMRValue == ( configMAX_API_CALL_INTERRUPT_PRIORITY << portPRIORITY_SHIFT ) )
+	{
+		/* Interrupts were already masked. */
+		ulReturn = pdTRUE;
+	}
+	else
+	{
+		ulReturn = pdFALSE;
+		/* s3_0_c4_c6_0 is ICC_PMR_EL1. */
+		__asm volatile ( "MSR s3_0_c4_c6_0, %0		\n"
+						 "DSB SY					\n"
+						 "ISB SY					\n"
+						 :: "r" ( configMAX_API_CALL_INTERRUPT_PRIORITY << portPRIORITY_SHIFT ) : "memory" );
+	}
+
+	portENABLE_INTERRUPTS();
+
+	return ulReturn;
+}
+/*-----------------------------------------------------------*/
+
+#if( configASSERT_DEFINED == 1 )
+
+	void vPortValidateInterruptPriority( void )
+	{
+		/* The following assertion will fail if a service routine (ISR) for
+		an interrupt that has been assigned a priority above
+		configMAX_SYSCALL_INTERRUPT_PRIORITY calls an ISR safe FreeRTOS API
+		function.  ISR safe FreeRTOS API functions must *only* be called
+		from interrupts that have been assigned a priority at or below
+		configMAX_SYSCALL_INTERRUPT_PRIORITY.
+
+		Numerically low interrupt priority numbers represent logically high
+		interrupt priorities, therefore the priority of the interrupt must
+		be set to a value equal to or numerically *higher* than
+		configMAX_SYSCALL_INTERRUPT_PRIORITY.
+
+		FreeRTOS maintains separate thread and ISR API functions to ensure
+		interrupt entry is as fast and simple as possible. */
+		uint64_t ullRunningInterruptPriority;
+		/* s3_0_c12_c11_3 is ICC_RPR_EL1. */
+		__asm volatile ( "MRS %0, s3_0_c12_c11_3" : "=r" ( ullRunningInterruptPriority ) );
+		configASSERT( ullRunningInterruptPriority >= ( configMAX_API_CALL_INTERRUPT_PRIORITY << portPRIORITY_SHIFT ) );
+	}
+
+#endif /* configASSERT_DEFINED */
+/*-----------------------------------------------------------*/
+
diff --git a/portable/GCC/ARM_CA53_64_BIT_SRE/portASM.S b/portable/GCC/ARM_CA53_64_BIT_SRE/portASM.S
new file mode 100644
index 0000000..79a5465
--- /dev/null
+++ b/portable/GCC/ARM_CA53_64_BIT_SRE/portASM.S
@@ -0,0 +1,400 @@
+/*
+ * FreeRTOS Kernel <DEVELOPMENT BRANCH>
+ * Copyright (C) 2021 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * https://www.FreeRTOS.org
+ * https://github.com/FreeRTOS
+ *
+ */
+
+	.text
+
+	/* Variables and functions. */
+	.extern ullMaxAPIPriorityMask
+	.extern pxCurrentTCB
+	.extern vTaskSwitchContext
+	.extern vApplicationIRQHandler
+	.extern ullPortInterruptNesting
+	.extern ullPortTaskHasFPUContext
+	.extern ullCriticalNesting
+	.extern ullPortYieldRequired
+	.extern _freertos_vector_table
+
+	.global FreeRTOS_IRQ_Handler
+	.global FreeRTOS_SWI_Handler
+	.global vPortRestoreTaskContext
+
+
+.macro portSAVE_CONTEXT
+
+	/* Switch to use the EL0 stack pointer. */
+	MSR 	SPSEL, #0
+
+	/* Save the entire context. */
+	STP 	X0, X1, [SP, #-0x10]!
+	STP 	X2, X3, [SP, #-0x10]!
+	STP 	X4, X5, [SP, #-0x10]!
+	STP 	X6, X7, [SP, #-0x10]!
+	STP 	X8, X9, [SP, #-0x10]!
+	STP 	X10, X11, [SP, #-0x10]!
+	STP 	X12, X13, [SP, #-0x10]!
+	STP 	X14, X15, [SP, #-0x10]!
+	STP 	X16, X17, [SP, #-0x10]!
+	STP 	X18, X19, [SP, #-0x10]!
+	STP 	X20, X21, [SP, #-0x10]!
+	STP 	X22, X23, [SP, #-0x10]!
+	STP 	X24, X25, [SP, #-0x10]!
+	STP 	X26, X27, [SP, #-0x10]!
+	STP 	X28, X29, [SP, #-0x10]!
+	STP 	X30, XZR, [SP, #-0x10]!
+
+	/* Save the SPSR. */
+#if defined( GUEST )
+	MRS		X3, SPSR_EL1
+	MRS		X2, ELR_EL1
+#else
+	MRS		X3, SPSR_EL3
+	/* Save the ELR. */
+	MRS		X2, ELR_EL3
+#endif
+
+	STP 	X2, X3, [SP, #-0x10]!
+
+	/* Save the critical section nesting depth. */
+	LDR		X0, ullCriticalNestingConst
+	LDR		X3, [X0]
+
+	/* Save the FPU context indicator. */
+	LDR		X0, ullPortTaskHasFPUContextConst
+	LDR		X2, [X0]
+
+	/* Save the FPU context, if any (32 128-bit registers). */
+	CMP		X2, #0
+	B.EQ	1f
+	STP		Q0, Q1, [SP,#-0x20]!
+	STP		Q2, Q3, [SP,#-0x20]!
+	STP		Q4, Q5, [SP,#-0x20]!
+	STP		Q6, Q7, [SP,#-0x20]!
+	STP		Q8, Q9, [SP,#-0x20]!
+	STP		Q10, Q11, [SP,#-0x20]!
+	STP		Q12, Q13, [SP,#-0x20]!
+	STP		Q14, Q15, [SP,#-0x20]!
+	STP		Q16, Q17, [SP,#-0x20]!
+	STP		Q18, Q19, [SP,#-0x20]!
+	STP		Q20, Q21, [SP,#-0x20]!
+	STP		Q22, Q23, [SP,#-0x20]!
+	STP		Q24, Q25, [SP,#-0x20]!
+	STP		Q26, Q27, [SP,#-0x20]!
+	STP		Q28, Q29, [SP,#-0x20]!
+	STP		Q30, Q31, [SP,#-0x20]!
+
+1:
+	/* Store the critical nesting count and FPU context indicator. */
+	STP 	X2, X3, [SP, #-0x10]!
+
+	LDR 	X0, pxCurrentTCBConst
+	LDR 	X1, [X0]
+	MOV 	X0, SP   /* Move SP into X0 for saving. */
+	STR 	X0, [X1]
+
+	/* Switch to use the ELx stack pointer. */
+	MSR 	SPSEL, #1
+
+	.endm
+
+; /**********************************************************************/
+
+.macro portRESTORE_CONTEXT
+
+	/* Switch to use the EL0 stack pointer. */
+	MSR 	SPSEL, #0
+
+	/* Set the SP to point to the stack of the task being restored. */
+	LDR		X0, pxCurrentTCBConst
+	LDR		X1, [X0]
+	LDR		X0, [X1]
+	MOV		SP, X0
+
+	LDP 	X2, X3, [SP], #0x10  /* Critical nesting and FPU context. */
+
+	/* Set the PMR register to be correct for the current critical nesting
+	depth. */
+	LDR		X0, ullCriticalNestingConst /* X0 holds the address of ullCriticalNesting. */
+	MOV		X1, #255					/* X1 holds the unmask value. */
+	CMP		X3, #0
+	B.EQ	1f
+	LDR		X6, ullMaxAPIPriorityMaskConst
+	LDR		X1, [X6]					/* X1 holds the mask value. */
+1:
+	MSR		s3_0_c4_c6_0, X1			/* Write the mask value to ICCPMR. s3_0_c4_c6_0 is ICC_PMR_EL1. */
+	DSB 	SY							/* _RB_Barriers probably not required here. */
+	ISB 	SY
+	STR		X3, [X0]					/* Restore the task's critical nesting count. */
+
+	/* Restore the FPU context indicator. */
+	LDR		X0, ullPortTaskHasFPUContextConst
+	STR		X2, [X0]
+
+	/* Restore the FPU context, if any. */
+	CMP		X2, #0
+	B.EQ	1f
+	LDP		Q30, Q31, [SP], #0x20
+	LDP		Q28, Q29, [SP], #0x20
+	LDP		Q26, Q27, [SP], #0x20
+	LDP		Q24, Q25, [SP], #0x20
+	LDP		Q22, Q23, [SP], #0x20
+	LDP		Q20, Q21, [SP], #0x20
+	LDP		Q18, Q19, [SP], #0x20
+	LDP		Q16, Q17, [SP], #0x20
+	LDP		Q14, Q15, [SP], #0x20
+	LDP		Q12, Q13, [SP], #0x20
+	LDP		Q10, Q11, [SP], #0x20
+	LDP		Q8, Q9, [SP], #0x20
+	LDP		Q6, Q7, [SP], #0x20
+	LDP		Q4, Q5, [SP], #0x20
+	LDP		Q2, Q3, [SP], #0x20
+	LDP		Q0, Q1, [SP], #0x20
+1:
+	LDP 	X2, X3, [SP], #0x10  /* SPSR and ELR. */
+
+#if defined( GUEST )
+	/* Restore the SPSR. */
+	MSR		SPSR_EL1, X3
+	/* Restore the ELR. */
+	MSR		ELR_EL1, X2
+#else
+	/* Restore the SPSR. */
+	MSR		SPSR_EL3, X3 /*_RB_ Assumes started in EL3. */
+	/* Restore the ELR. */
+	MSR		ELR_EL3, X2
+#endif
+
+	LDP 	X30, XZR, [SP], #0x10
+	LDP 	X28, X29, [SP], #0x10
+	LDP 	X26, X27, [SP], #0x10
+	LDP 	X24, X25, [SP], #0x10
+	LDP 	X22, X23, [SP], #0x10
+	LDP 	X20, X21, [SP], #0x10
+	LDP 	X18, X19, [SP], #0x10
+	LDP 	X16, X17, [SP], #0x10
+	LDP 	X14, X15, [SP], #0x10
+	LDP 	X12, X13, [SP], #0x10
+	LDP 	X10, X11, [SP], #0x10
+	LDP 	X8, X9, [SP], #0x10
+	LDP 	X6, X7, [SP], #0x10
+	LDP 	X4, X5, [SP], #0x10
+	LDP 	X2, X3, [SP], #0x10
+	LDP 	X0, X1, [SP], #0x10
+
+	/* Switch to use the ELx stack pointer.  _RB_ Might not be required. */
+	MSR 	SPSEL, #1
+
+	ERET
+
+	.endm
+
+
+/******************************************************************************
+ * FreeRTOS_SWI_Handler handler is used to perform a context switch.
+ *****************************************************************************/
+.align 8
+.type FreeRTOS_SWI_Handler, %function
+FreeRTOS_SWI_Handler:
+	/* Save the context of the current task and select a new task to run. */
+	portSAVE_CONTEXT
+#if defined( GUEST )
+	MRS		X0, ESR_EL1
+#else
+	MRS		X0, ESR_EL3
+#endif
+
+	LSR		X1, X0, #26
+
+#if defined( GUEST )
+	CMP		X1, #0x15 	/* 0x15 = SVC instruction. */
+#else
+	CMP		X1, #0x17 	/* 0x17 = SMC instruction. */
+#endif
+	B.NE	FreeRTOS_Abort
+	BL 		vTaskSwitchContext
+
+	portRESTORE_CONTEXT
+
+FreeRTOS_Abort:
+	/* Full ESR is in X0, exception class code is in X1. */
+	B		.
+
+/******************************************************************************
+ * vPortRestoreTaskContext is used to start the scheduler.
+ *****************************************************************************/
+.align 8
+.type vPortRestoreTaskContext, %function
+vPortRestoreTaskContext:
+.set freertos_vector_base,	_freertos_vector_table
+
+	/* Install the FreeRTOS interrupt handlers. */
+	LDR		X1, =freertos_vector_base
+#if defined( GUEST )
+	MSR		VBAR_EL1, X1
+#else
+	MSR		VBAR_EL3, X1
+#endif
+	DSB		SY
+	ISB		SY
+
+	/* Start the first task. */
+	portRESTORE_CONTEXT
+
+
+/******************************************************************************
+ * FreeRTOS_IRQ_Handler handles IRQ entry and exit.
+ *****************************************************************************/
+.align 8
+.type FreeRTOS_IRQ_Handler, %function
+FreeRTOS_IRQ_Handler:
+	/* Save volatile registers. */
+	STP		X0, X1, [SP, #-0x10]!
+	STP		X2, X3, [SP, #-0x10]!
+	STP		X4, X5, [SP, #-0x10]!
+	STP		X6, X7, [SP, #-0x10]!
+	STP		X8, X9, [SP, #-0x10]!
+	STP		X10, X11, [SP, #-0x10]!
+	STP		X12, X13, [SP, #-0x10]!
+	STP		X14, X15, [SP, #-0x10]!
+	STP		X16, X17, [SP, #-0x10]!
+	STP		X18, X19, [SP, #-0x10]!
+	STP		X29, X30, [SP, #-0x10]!
+
+	/* Save the SPSR and ELR. */
+#if defined( GUEST )
+	MRS		X3, SPSR_EL1
+	MRS		X2, ELR_EL1
+#else
+	MRS		X3, SPSR_EL3
+	MRS		X2, ELR_EL3
+#endif
+	STP 	X2, X3, [SP, #-0x10]!
+
+	/* Increment the interrupt nesting counter. */
+	LDR		X5, ullPortInterruptNestingConst
+	LDR		X1, [X5]	/* Old nesting count in X1. */
+	ADD		X6, X1, #1
+	STR		X6, [X5]	/* Address of nesting count variable in X5. */
+
+	/* Maintain the interrupt nesting information across the function call. */
+	STP		X1, X5, [SP, #-0x10]!
+
+	/* Call the C handler. */
+	BL vApplicationIRQHandler
+
+	/* Disable interrupts. */
+	MSR 	DAIFSET, #2
+	DSB		SY
+	ISB		SY
+
+	/* Restore the critical nesting count. */
+	LDP		X1, X5, [SP], #0x10
+	STR		X1, [X5]
+
+	/* Has interrupt nesting unwound? */
+	CMP		X1, #0
+	B.NE	Exit_IRQ_No_Context_Switch
+
+	/* Is a context switch required? */
+	LDR		X0, ullPortYieldRequiredConst
+	LDR		X1, [X0]
+	CMP		X1, #0
+	B.EQ	Exit_IRQ_No_Context_Switch
+
+	/* Reset ullPortYieldRequired to 0. */
+	MOV		X2, #0
+	STR		X2, [X0]
+
+	/* Restore volatile registers. */
+	LDP 	X4, X5, [SP], #0x10  /* SPSR and ELR. */
+#if defined( GUEST )
+	MSR		SPSR_EL1, X5
+	MSR		ELR_EL1, X4
+#else
+	MSR		SPSR_EL3, X5 /*_RB_ Assumes started in EL3. */
+	MSR		ELR_EL3, X4
+#endif
+	DSB		SY
+	ISB		SY
+
+	LDP		X29, X30, [SP], #0x10
+	LDP		X18, X19, [SP], #0x10
+	LDP		X16, X17, [SP], #0x10
+	LDP		X14, X15, [SP], #0x10
+	LDP		X12, X13, [SP], #0x10
+	LDP		X10, X11, [SP], #0x10
+	LDP		X8, X9, [SP], #0x10
+	LDP		X6, X7, [SP], #0x10
+	LDP		X4, X5, [SP], #0x10
+	LDP		X2, X3, [SP], #0x10
+	LDP		X0, X1, [SP], #0x10
+
+	/* Save the context of the current task and select a new task to run. */
+	portSAVE_CONTEXT
+	BL vTaskSwitchContext
+	portRESTORE_CONTEXT
+
+Exit_IRQ_No_Context_Switch:
+	/* Restore volatile registers. */
+	LDP 	X4, X5, [SP], #0x10  /* SPSR and ELR. */
+#if defined( GUEST )
+	MSR		SPSR_EL1, X5
+	MSR		ELR_EL1, X4
+#else
+	MSR		SPSR_EL3, X5 /*_RB_ Assumes started in EL3. */
+	MSR		ELR_EL3, X4
+#endif
+	DSB		SY
+	ISB		SY
+
+	LDP		X29, X30, [SP], #0x10
+	LDP		X18, X19, [SP], #0x10
+	LDP		X16, X17, [SP], #0x10
+	LDP		X14, X15, [SP], #0x10
+	LDP		X12, X13, [SP], #0x10
+	LDP		X10, X11, [SP], #0x10
+	LDP		X8, X9, [SP], #0x10
+	LDP		X6, X7, [SP], #0x10
+	LDP		X4, X5, [SP], #0x10
+	LDP		X2, X3, [SP], #0x10
+	LDP		X0, X1, [SP], #0x10
+
+	ERET
+
+
+
+
+.align 8
+pxCurrentTCBConst: .dword pxCurrentTCB
+ullCriticalNestingConst: .dword ullCriticalNesting
+ullPortTaskHasFPUContextConst: .dword ullPortTaskHasFPUContext
+
+ullMaxAPIPriorityMaskConst: .dword ullMaxAPIPriorityMask
+ullPortInterruptNestingConst: .dword ullPortInterruptNesting
+ullPortYieldRequiredConst: .dword ullPortYieldRequired
+
+.end
diff --git a/portable/GCC/ARM_CA53_64_BIT_SRE/portmacro.h b/portable/GCC/ARM_CA53_64_BIT_SRE/portmacro.h
new file mode 100644
index 0000000..2cfeb80
--- /dev/null
+++ b/portable/GCC/ARM_CA53_64_BIT_SRE/portmacro.h
@@ -0,0 +1,197 @@
+/*
+ * FreeRTOS Kernel <DEVELOPMENT BRANCH>
+ * Copyright (C) 2021 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * https://www.FreeRTOS.org
+ * https://github.com/FreeRTOS
+ *
+ */
+
+#ifndef PORTMACRO_H
+#define PORTMACRO_H
+
+#ifdef __cplusplus
+	extern "C" {
+#endif
+
+/*-----------------------------------------------------------
+ * Port specific definitions.
+ *
+ * The settings in this file configure FreeRTOS correctly for the given hardware
+ * and compiler.
+ *
+ * These settings should not be altered.
+ *-----------------------------------------------------------
+ */
+
+/* Type definitions. */
+#define portCHAR		char
+#define portFLOAT		float
+#define portDOUBLE		double
+#define portLONG		long
+#define portSHORT		short
+#define portSTACK_TYPE	size_t
+#define portBASE_TYPE	long
+
+typedef portSTACK_TYPE StackType_t;
+typedef portBASE_TYPE BaseType_t;
+typedef uint64_t UBaseType_t;
+
+typedef uint64_t TickType_t;
+#define portMAX_DELAY ( ( TickType_t ) 0xffffffffffffffff )
+
+/* 32-bit tick type on a 32-bit architecture, so reads of the tick count do
+not need to be guarded with a critical section. */
+#define portTICK_TYPE_IS_ATOMIC 1
+
+/*-----------------------------------------------------------*/
+
+/* Hardware specifics. */
+#define portSTACK_GROWTH			( -1 )
+#define portTICK_PERIOD_MS			( ( TickType_t ) 1000 / configTICK_RATE_HZ )
+#define portBYTE_ALIGNMENT			16
+#define portPOINTER_SIZE_TYPE 		uint64_t
+
+/*-----------------------------------------------------------*/
+
+/* Task utilities. */
+
+/* Called at the end of an ISR that can cause a context switch. */
+#define portEND_SWITCHING_ISR( xSwitchRequired )\
+{												\
+extern uint64_t ullPortYieldRequired;			\
+												\
+	if( xSwitchRequired != pdFALSE )			\
+	{											\
+		ullPortYieldRequired = pdTRUE;			\
+	}											\
+}
+
+#define portYIELD_FROM_ISR( x ) portEND_SWITCHING_ISR( x )
+#if defined( GUEST )
+	#define portYIELD() __asm volatile ( "SVC 0" ::: "memory" )
+#else
+	#define portYIELD() __asm volatile ( "SMC 0" ::: "memory" )
+#endif
+/*-----------------------------------------------------------
+ * Critical section control
+ *----------------------------------------------------------*/
+
+extern void vPortEnterCritical( void );
+extern void vPortExitCritical( void );
+extern UBaseType_t uxPortSetInterruptMask( void );
+extern void vPortClearInterruptMask( UBaseType_t uxNewMaskValue );
+extern void vPortInstallFreeRTOSVectorTable( void );
+
+#define portDISABLE_INTERRUPTS()									\
+	__asm volatile ( "MSR DAIFSET, #2" ::: "memory" );				\
+	__asm volatile ( "DSB SY" );									\
+	__asm volatile ( "ISB SY" );
+
+#define portENABLE_INTERRUPTS()										\
+	__asm volatile ( "MSR DAIFCLR, #2" ::: "memory" );				\
+	__asm volatile ( "DSB SY" );									\
+	__asm volatile ( "ISB SY" );
+
+
+/* These macros do not globally disable/enable interrupts.  They do mask off
+interrupts that have a priority below configMAX_API_CALL_INTERRUPT_PRIORITY. */
+#define portENTER_CRITICAL()		vPortEnterCritical();
+#define portEXIT_CRITICAL()			vPortExitCritical();
+#define portSET_INTERRUPT_MASK_FROM_ISR()		uxPortSetInterruptMask()
+#define portCLEAR_INTERRUPT_MASK_FROM_ISR(x)	vPortClearInterruptMask(x)
+
+/*-----------------------------------------------------------*/
+
+/* Task function macros as described on the FreeRTOS.org WEB site.  These are
+not required for this port but included in case common demo code that uses these
+macros is used. */
+#define portTASK_FUNCTION_PROTO( vFunction, pvParameters )	void vFunction( void *pvParameters )
+#define portTASK_FUNCTION( vFunction, pvParameters )	void vFunction( void *pvParameters )
+
+/* Prototype of the FreeRTOS tick handler.  This must be installed as the
+handler for whichever peripheral is used to generate the RTOS tick. */
+void FreeRTOS_Tick_Handler( void );
+
+/* Any task that uses the floating point unit MUST call vPortTaskUsesFPU()
+before any floating point instructions are executed. */
+void vPortTaskUsesFPU( void );
+#define portTASK_USES_FLOATING_POINT() vPortTaskUsesFPU()
+
+#define portLOWEST_INTERRUPT_PRIORITY ( ( ( uint32_t ) configUNIQUE_INTERRUPT_PRIORITIES ) - 1UL )
+#define portLOWEST_USABLE_INTERRUPT_PRIORITY ( portLOWEST_INTERRUPT_PRIORITY - 1UL )
+
+/* Architecture specific optimisations. */
+#ifndef configUSE_PORT_OPTIMISED_TASK_SELECTION
+	#define configUSE_PORT_OPTIMISED_TASK_SELECTION 1
+#endif
+
+#if configUSE_PORT_OPTIMISED_TASK_SELECTION == 1
+
+	/* Store/clear the ready priorities in a bit map. */
+	#define portRECORD_READY_PRIORITY( uxPriority, uxReadyPriorities ) ( uxReadyPriorities ) |= ( 1UL << ( uxPriority ) )
+	#define portRESET_READY_PRIORITY( uxPriority, uxReadyPriorities ) ( uxReadyPriorities ) &= ~( 1UL << ( uxPriority ) )
+
+	/*-----------------------------------------------------------*/
+
+	#define portGET_HIGHEST_PRIORITY( uxTopPriority, uxReadyPriorities ) uxTopPriority = ( 31 - __builtin_clz( uxReadyPriorities ) )
+
+#endif /* configUSE_PORT_OPTIMISED_TASK_SELECTION */
+
+#ifdef configASSERT
+	void vPortValidateInterruptPriority( void );
+	#define portASSERT_IF_INTERRUPT_PRIORITY_INVALID() 	vPortValidateInterruptPriority()
+#endif /* configASSERT */
+
+#define portNOP() __asm volatile( "NOP" )
+#define portINLINE __inline
+
+#ifdef __cplusplus
+	} /* extern C */
+#endif
+
+
+/* The number of bits to shift for an interrupt priority is dependent on the
+number of bits implemented by the interrupt controller. */
+#if configUNIQUE_INTERRUPT_PRIORITIES == 16
+	#define portPRIORITY_SHIFT 4
+	#define portMAX_BINARY_POINT_VALUE	3
+#elif configUNIQUE_INTERRUPT_PRIORITIES == 32
+	#define portPRIORITY_SHIFT 3
+	#define portMAX_BINARY_POINT_VALUE	2
+#elif configUNIQUE_INTERRUPT_PRIORITIES == 64
+	#define portPRIORITY_SHIFT 2
+	#define portMAX_BINARY_POINT_VALUE	1
+#elif configUNIQUE_INTERRUPT_PRIORITIES == 128
+	#define portPRIORITY_SHIFT 1
+	#define portMAX_BINARY_POINT_VALUE	0
+#elif configUNIQUE_INTERRUPT_PRIORITIES == 256
+	#define portPRIORITY_SHIFT 0
+	#define portMAX_BINARY_POINT_VALUE	0
+#else
+	#error Invalid configUNIQUE_INTERRUPT_PRIORITIES setting.  configUNIQUE_INTERRUPT_PRIORITIES must be set to the number of unique priorities implemented by the target hardware
+#endif
+
+#define portMEMORY_BARRIER() __asm volatile( "" ::: "memory" )
+
+#endif /* PORTMACRO_H */
+