fix potential speculative access that might trigger bus faults on Cortex-M7 #90305
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Due to erratum ERR011573, speculative accesses might be performed to normal memory unmapped in the MPU. This can be avoided by using MPU region 0 to cover all unmapped memory and make this region execute-never and inaccessible. Fixes zephyrproject-rtos#89852 Co-authored-by: Peter van der Perk <peter.vanderperk@nxp.com> Signed-off-by: Manuel Argüelles <manuel.arguelles@nxp.com>
Due to erratum 1013783-B, speculative accesses might be performed to normal memory unmapped in the MPU. This can be avoided by using MPU region 0 to cover all unmapped memory and make this region execute-never and inaccessible. Note that this applies when CPU Cortex-M7 implements MPU and D-cache. Signed-off-by: Manuel Argüelles <manuel.arguelles@nxp.com>
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| /* Erratum 1013783-B (SDEN-1068427): use first region to prevent speculative access | ||
| * in entire memory space | ||
| */ | ||
| MPU_REGION_ENTRY("BACKGROUND", |
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nit: "UNMAPPED" would be a better name
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I didn’t get to address this due to the timezone difference, already merged :)
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Due to erratum 1013783-B, speculative accesses might be performed to normal memory unmapped in the MPU. This can be avoided by using MPU region 0 to cover all unmapped memory and make this region execute-never and inaccessible.
Note that this applies for all Cortex-M7 revisions implementing MPU and D-cache, so although the issue was reported for
mr_canhubk3board that implements custom SoC MPU regions, I added the fix for any Cortex-M7 SoC having those features enabled.Fixes #89852