| /* | |
| * 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 | |
| * | |
| */ | |
| /* Secure context includes. */ | |
| #include "secure_context.h" | |
| /* Secure heap includes. */ | |
| #include "secure_heap.h" | |
| /* Secure port macros. */ | |
| #include "secure_port_macros.h" | |
| /** | |
| * @brief CONTROL value for privileged tasks. | |
| * | |
| * Bit[0] - 0 --> Thread mode is privileged. | |
| * Bit[1] - 1 --> Thread mode uses PSP. | |
| */ | |
| #define securecontextCONTROL_VALUE_PRIVILEGED 0x02 | |
| /** | |
| * @brief CONTROL value for un-privileged tasks. | |
| * | |
| * Bit[0] - 1 --> Thread mode is un-privileged. | |
| * Bit[1] - 1 --> Thread mode uses PSP. | |
| */ | |
| #define securecontextCONTROL_VALUE_UNPRIVILEGED 0x03 | |
| /** | |
| * @brief Invalid context ID. | |
| */ | |
| #define securecontextINVALID_CONTEXT_ID 0UL | |
| /** | |
| * @brief Maximum number of secure contexts. | |
| */ | |
| #ifndef secureconfigMAX_SECURE_CONTEXTS | |
| #define secureconfigMAX_SECURE_CONTEXTS 8UL | |
| #endif | |
| /*-----------------------------------------------------------*/ | |
| /** | |
| * @brief Pre-allocated array of secure contexts. | |
| */ | |
| SecureContext_t xSecureContexts[ secureconfigMAX_SECURE_CONTEXTS ]; | |
| /*-----------------------------------------------------------*/ | |
| /** | |
| * @brief Get a free context from the secure context pool (xSecureContexts). | |
| * | |
| * @return Index of a free context in the xSecureContexts array. | |
| */ | |
| static uint32_t ulGetSecureContext( void ); | |
| /** | |
| * @brief Return the secure context to the secure context pool (xSecureContexts). | |
| * | |
| * @param[in] ulSecureContextIndex Index of the context in the xSecureContexts array. | |
| */ | |
| static void vReturnSecureContext( uint32_t ulSecureContextIndex ); | |
| /* These are implemented in assembly. */ | |
| extern void SecureContext_LoadContextAsm( SecureContext_t * pxSecureContext ); | |
| extern void SecureContext_SaveContextAsm( SecureContext_t * pxSecureContext ); | |
| /*-----------------------------------------------------------*/ | |
| static uint32_t ulGetSecureContext( void ) | |
| { | |
| uint32_t ulSecureContextIndex; | |
| for( ulSecureContextIndex = 0; ulSecureContextIndex < secureconfigMAX_SECURE_CONTEXTS; ulSecureContextIndex++ ) | |
| { | |
| if( ( xSecureContexts[ ulSecureContextIndex ].pucCurrentStackPointer == NULL ) && | |
| ( xSecureContexts[ ulSecureContextIndex ].pucStackLimit == NULL ) && | |
| ( xSecureContexts[ ulSecureContextIndex ].pucStackStart == NULL ) ) | |
| { | |
| break; | |
| } | |
| } | |
| return ulSecureContextIndex; | |
| } | |
| /*-----------------------------------------------------------*/ | |
| static void vReturnSecureContext( uint32_t ulSecureContextIndex ) | |
| { | |
| xSecureContexts[ ulSecureContextIndex ].pucCurrentStackPointer = NULL; | |
| xSecureContexts[ ulSecureContextIndex ].pucStackLimit = NULL; | |
| xSecureContexts[ ulSecureContextIndex ].pucStackStart = NULL; | |
| } | |
| /*-----------------------------------------------------------*/ | |
| secureportNON_SECURE_CALLABLE void SecureContext_Init( void ) | |
| { | |
| uint32_t ulIPSR, i; | |
| /* Read the Interrupt Program Status Register (IPSR) value. */ | |
| secureportREAD_IPSR( ulIPSR ); | |
| /* Do nothing if the processor is running in the Thread Mode. IPSR is zero | |
| * when the processor is running in the Thread Mode. */ | |
| if( ulIPSR != 0 ) | |
| { | |
| /* No stack for thread mode until a task's context is loaded. */ | |
| secureportSET_PSPLIM( securecontextNO_STACK ); | |
| secureportSET_PSP( securecontextNO_STACK ); | |
| /* Initialize all secure contexts. */ | |
| for( i = 0; i < secureconfigMAX_SECURE_CONTEXTS; i++ ) | |
| { | |
| xSecureContexts[ i ].pucCurrentStackPointer = NULL; | |
| xSecureContexts[ i ].pucStackLimit = NULL; | |
| xSecureContexts[ i ].pucStackStart = NULL; | |
| } | |
| #if ( configENABLE_MPU == 1 ) | |
| { | |
| /* Configure thread mode to use PSP and to be unprivileged. */ | |
| secureportSET_CONTROL( securecontextCONTROL_VALUE_UNPRIVILEGED ); | |
| } | |
| #else /* configENABLE_MPU */ | |
| { | |
| /* Configure thread mode to use PSP and to be privileged. */ | |
| secureportSET_CONTROL( securecontextCONTROL_VALUE_PRIVILEGED ); | |
| } | |
| #endif /* configENABLE_MPU */ | |
| } | |
| } | |
| /*-----------------------------------------------------------*/ | |
| #if ( configENABLE_MPU == 1 ) | |
| secureportNON_SECURE_CALLABLE SecureContextHandle_t SecureContext_AllocateContext( uint32_t ulSecureStackSize, | |
| uint32_t ulIsTaskPrivileged ) | |
| #else /* configENABLE_MPU */ | |
| secureportNON_SECURE_CALLABLE SecureContextHandle_t SecureContext_AllocateContext( uint32_t ulSecureStackSize ) | |
| #endif /* configENABLE_MPU */ | |
| { | |
| uint8_t * pucStackMemory = NULL; | |
| uint32_t ulIPSR, ulSecureContextIndex; | |
| SecureContextHandle_t xSecureContextHandle; | |
| #if ( configENABLE_MPU == 1 ) | |
| uint32_t * pulCurrentStackPointer = NULL; | |
| #endif /* configENABLE_MPU */ | |
| /* Read the Interrupt Program Status Register (IPSR) value. */ | |
| secureportREAD_IPSR( ulIPSR ); | |
| /* Do nothing if the processor is running in the Thread Mode. IPSR is zero | |
| * when the processor is running in the Thread Mode. */ | |
| if( ulIPSR != 0 ) | |
| { | |
| /* Ontain a free secure context. */ | |
| ulSecureContextIndex = ulGetSecureContext(); | |
| /* Were we able to get a free context? */ | |
| if( ulSecureContextIndex < secureconfigMAX_SECURE_CONTEXTS ) | |
| { | |
| /* Allocate the stack space. */ | |
| pucStackMemory = pvPortMalloc( ulSecureStackSize ); | |
| if( pucStackMemory != NULL ) | |
| { | |
| /* Since stack grows down, the starting point will be the last | |
| * location. Note that this location is next to the last | |
| * allocated byte because the hardware decrements the stack | |
| * pointer before writing i.e. if stack pointer is 0x2, a push | |
| * operation will decrement the stack pointer to 0x1 and then | |
| * write at 0x1. */ | |
| xSecureContexts[ ulSecureContextIndex ].pucStackStart = pucStackMemory + ulSecureStackSize; | |
| /* The stack cannot go beyond this location. This value is | |
| * programmed in the PSPLIM register on context switch.*/ | |
| xSecureContexts[ ulSecureContextIndex ].pucStackLimit = pucStackMemory; | |
| #if ( configENABLE_MPU == 1 ) | |
| { | |
| /* Store the correct CONTROL value for the task on the stack. | |
| * This value is programmed in the CONTROL register on | |
| * context switch. */ | |
| pulCurrentStackPointer = ( uint32_t * ) xSecureContexts[ ulSecureContextIndex ].pucStackStart; | |
| pulCurrentStackPointer--; | |
| if( ulIsTaskPrivileged ) | |
| { | |
| *( pulCurrentStackPointer ) = securecontextCONTROL_VALUE_PRIVILEGED; | |
| } | |
| else | |
| { | |
| *( pulCurrentStackPointer ) = securecontextCONTROL_VALUE_UNPRIVILEGED; | |
| } | |
| /* Store the current stack pointer. This value is programmed in | |
| * the PSP register on context switch. */ | |
| xSecureContexts[ ulSecureContextIndex ].pucCurrentStackPointer = ( uint8_t * ) pulCurrentStackPointer; | |
| } | |
| #else /* configENABLE_MPU */ | |
| { | |
| /* Current SP is set to the starting of the stack. This | |
| * value programmed in the PSP register on context switch. */ | |
| xSecureContexts[ ulSecureContextIndex ].pucCurrentStackPointer = xSecureContexts[ ulSecureContextIndex ].pucStackStart; | |
| } | |
| #endif /* configENABLE_MPU */ | |
| /* Ensure to never return 0 as a valid context handle. */ | |
| xSecureContextHandle = ulSecureContextIndex + 1UL; | |
| } | |
| else | |
| { | |
| xSecureContextHandle = securecontextINVALID_CONTEXT_ID; | |
| } | |
| } | |
| } | |
| return xSecureContextHandle; | |
| } | |
| /*-----------------------------------------------------------*/ | |
| secureportNON_SECURE_CALLABLE void SecureContext_FreeContext( SecureContextHandle_t xSecureContextHandle ) | |
| { | |
| uint32_t ulIPSR, ulSecureContextIndex; | |
| /* Read the Interrupt Program Status Register (IPSR) value. */ | |
| secureportREAD_IPSR( ulIPSR ); | |
| /* Do nothing if the processor is running in the Thread Mode. IPSR is zero | |
| * when the processor is running in the Thread Mode. */ | |
| if( ulIPSR != 0 ) | |
| { | |
| /* Only free if a valid context handle is passed. */ | |
| if( ( xSecureContextHandle > 0UL ) && ( xSecureContextHandle <= secureconfigMAX_SECURE_CONTEXTS ) ) | |
| { | |
| ulSecureContextIndex = xSecureContextHandle - 1UL; | |
| /* Free the stack space. */ | |
| vPortFree( xSecureContexts[ ulSecureContextIndex ].pucStackLimit ); | |
| /* Return the context back to the free contexts pool. */ | |
| vReturnSecureContext( ulSecureContextIndex ); | |
| } | |
| } | |
| } | |
| /*-----------------------------------------------------------*/ | |
| secureportNON_SECURE_CALLABLE void SecureContext_LoadContext( SecureContextHandle_t xSecureContextHandle ) | |
| { | |
| uint32_t ulSecureContextIndex; | |
| if( ( xSecureContextHandle > 0UL ) && ( xSecureContextHandle <= secureconfigMAX_SECURE_CONTEXTS ) ) | |
| { | |
| ulSecureContextIndex = xSecureContextHandle - 1UL; | |
| SecureContext_LoadContextAsm( &( xSecureContexts[ ulSecureContextIndex ] ) ); | |
| } | |
| } | |
| /*-----------------------------------------------------------*/ | |
| secureportNON_SECURE_CALLABLE void SecureContext_SaveContext( SecureContextHandle_t xSecureContextHandle ) | |
| { | |
| uint32_t ulSecureContextIndex; | |
| if( ( xSecureContextHandle > 0UL ) && ( xSecureContextHandle <= secureconfigMAX_SECURE_CONTEXTS ) ) | |
| { | |
| ulSecureContextIndex = xSecureContextHandle - 1UL; | |
| SecureContext_SaveContextAsm( &( xSecureContexts[ ulSecureContextIndex ] ) ); | |
| } | |
| } | |
| /*-----------------------------------------------------------*/ |