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If xTaskCreate API is used to create a task, the task's stack is allocated on heap using pvPortMalloc. This places the task's stack in the privileged data section, if the heap is placed in the privileged data section. We use a separate MPU region to grant a task access to its stack. If the task's stack is in the privileged data section, this results in overlapping MPU regions as privileged data section is already protected using a separate MPU region. ARMv8-M does not allow overlapping MPU regions and this results in a fault. This commit ensures to not use a separate MPU region for the task's stack if it lies within the privileged data section. Note that if the heap memory is placed in the privileged data section, the xTaskCreate API cannot be used to create an unprivileged task as the task's stack will be in the privileged data section and the task won't have access to it. xTaskCreateRestricted and xTaskCreateRestrictedStatic API should be used to create unprivileged tasks. Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>
Each real time kernel port consists of three files that contain the core kernel components and are common to every port, and one or more files that are specific to a particular microcontroller and/or compiler. + The FreeRTOS/Source/Portable/MemMang directory contains the five sample memory allocators as described on the http://www.FreeRTOS.org WEB site. + The other directories each contain files specific to a particular microcontroller or compiler, where the directory name denotes the compiler specific files the directory contains. For example, if you are interested in the [compiler] port for the [architecture] microcontroller, then the port specific files are contained in FreeRTOS/Source/Portable/[compiler]/[architecture] directory. If this is the only port you are interested in then all the other directories can be ignored.