Add check for if the scheduler is running to MPU ports

[Skptak]

Description

Add a check for if the scheduler is running to xPortIsAuthorizedToAccessBuffer().

This fixes an issue where before the scheduler is started APIs can fail as the TCB pointed to by pxCurrentTCB may not have access to requested APIs.

Test Steps

Call xTimerStart(), which calls MPU_xTimerGenericCommandFromTask:

xReturn = MPU_xTimerGenericCommandFromTaskEntry( &( xParams ) );

Which calls MPU_xTimerGenericCommandFromTaskEntry

BaseType_t MPU_xTimerGenericCommandFromTaskEntry(
    const xTimerGenericCommandFromTaskParams_t * pxParams
 ) /* __attribute__ (( naked )) FREERTOS_SYSTEM_CALL */
    {
        __asm volatile
        (
            " .syntax unified                                               \n"
            " .extern MPU_xTimerGenericCommandFromTaskImpl                  \n"
            "                                                               \n"
            " push {r0}                                                     \n"
            " mrs r0, control                                               \n"
            " tst r0, #1                                                    \n"
            " bne MPU_xTimerGenericCommandFromTask_Unpriv                   \n"
            " MPU_xTimerGenericCommandFromTask_Priv:                        \n"
            "     pop {r0}                                                  \n"
            "     b MPU_xTimerGenericCommandFromTaskImpl                    \n"

This calls MPU_xTimerGenericCommandFromTaskImpl:

xAreParamsReadable = xPortIsAuthorizedToAccessBuffer( pxParams,
                                            sizeof( xTimerGenericCommandFromTaskParams_t ),
                                            tskMPU_READ_PERMISSION );
}

Which calls xPortIsAuthorizedToAccessBuffer This loads pxCurrentTCB to check if you are allowed to start the timer

BaseType_t xPortIsAuthorizedToAccessBuffer(
    const void * pvBuffer,
    uint32_t ulBufferLength,
    uint32_t ulAccessRequested
) /* PRIVILEGED_FUNCTION */
{
    uint32_t i, ulBufferStartAddress, ulBufferEndAddress;
    BaseType_t xAccessGranted = pdFALSE;
    const xMPU_SETTINGS * xTaskMpuSettings = xTaskGetMPUSettings( NULL ); /* Calling task's MPU settings. */

    if( ( xTaskMpuSettings->ulTaskFlags & portTASK_IS_PRIVILEGED_FLAG ) == portTASK_IS_PRIVILEGED_FLAG )
    {
            xAccessGranted = pdTRUE;
    }
    else
    {
        <CHECK_IF_ACCESS_ALLOWED>

However, there's no actual calling task that made this call. It just checks whatever TCB happens to be there.

A check is needed for when the scheduler is not running yet, as at this point the current TCB is irrelevant to the operation being performed.

Checklist:

• [ ] I have tested my changes. No regression in existing tests.
• [ ] I have modified and/or added unit-tests to cover the code changes in this Pull Request.

Related Issue

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (cf2366c) 93.42% compared to head (921ea9a) 93.42%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #954 +/- ## ======================================= Coverage 93.42% 93.42% ======================================= Files 6 6 Lines 3196 3196 Branches 886 886 ======================================= Hits 2986 2986 Misses 103 103 Partials 107 107 ``` | [Flag](https://app.codecov.io/gh/FreeRTOS/FreeRTOS-Kernel/pull/954/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=FreeRTOS) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/FreeRTOS/FreeRTOS-Kernel/pull/954/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=FreeRTOS) | `93.42% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=FreeRTOS#carryforward-flags-in-the-pull-request-comment) to find out more.

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[sonarcloud[bot]]

Quality Gate passed

Kudos, no new issues were introduced!

0 New issues
0 Security Hotspots
No data about Coverage
No data about Duplication

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