arm64: arm_mpu: Add userspace
Add dynamic_areas_init. It will mark a mpu region as a dynamic region
area. The dynamic region areas is designed to be the background
regions, so that the system could re-program the thread regions on
the backgroud regions.
Add configure_dynamic_mpu_regions to re-program the thread regions on
the backgroud regions. The configure_dynamic_mpu_regions function is
the core function of implementing the userspace for the MPU. This
function is used in thread creation and context switch.
During context switch, the pre thread's regions should be disabled,
and the new thread's regions will be re-programed. Since the thread's
stack region will also be switched, there will be a problem before
new thread's region being re-programed which is the new thread's
stack usage. To avoid the exception generated by stack usage caused by
unprogramed new thread's stack region, I disable mpu first before
flush_dynamic_regions_to_mpu and then enable it.
Signed-off-by: Jaxson Han <jaxson.han@arm.com>
1 file changed
