Fix portSWITCH_TO_USER_MODE() on Armv7-M MPU ports

Skptak commented 1 year ago

Description

A task's privilege level is stored in ulTaskFlag member in the TCB. Current implementation of portSWITCH_TO_USER_MODE() does not update this flag but just lowers the processor's privilege level. This results in many APIs incorrectly determining task's privilege level and access permissions -

xPortIsAuthorizedToAccessBuffer
xPortIsTaskPrivileged
xPortIsAuthorizedToAccessKernelObject

This PR fixes the portSWITCH_TO_USER_MODE() implementation to correctly update the ulTaskFlag member in the TCB before lowering the processor's privilege level.

Test Steps

Tested on Cortex-M7.

Checklist:

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

Related Issue

NA.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

codecov[bot] commented 1 year ago

Codecov Report

All modified lines are covered by tests :white_check_mark:

Comparison is base (ac5deb1) 93.62% compared to head (7721ab0) 93.62%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #803 +/- ## ======================================= Coverage 93.62% 93.62% ======================================= Files 6 6 Lines 2508 2508 Branches 598 598 ======================================= Hits 2348 2348 Misses 107 107 Partials 53 53 ``` | [Flag](https://app.codecov.io/gh/FreeRTOS/FreeRTOS-Kernel/pull/803/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/803/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=FreeRTOS) | `93.62% <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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Skptak commented 1 year ago

/bot run formatting