arm: nxp: mpu: Rework handling of region descriptor 0
The NXP MPU requires special handling of region descriptor 0 to
guarantee that the debugger has access to the entire address space. It
does not allow writes from the core to affect the start or end
addresses, or the permissions associated with the debugger.
The original implementation of this driver attempted to work around
region descriptor 0, resulting in an off-by-1 error caught by Coverity.
Instead, define region descriptor 0 explicitly in the mpu_regions array,
and add some asserts to ensure that one doesn't try to change its start
or end addresses. This has an added benefit such that more permissions
can be enabled in region 0 if desired, whereas the previous
implementation always forced all writable permissions to be cleared.
Coverity-CID: 170473
Jira: ZEP-2258
Signed-off-by: Maureen Helm <maureen.helm@nxp.com>
2 files changed
