Introduce a Kconfig option to allow Secure function calls to be
pre-empted.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>
Signed-off-by: Øyvind Rønningstad <oyvind.ronningstad@nordicsemi.no>

This adds code to swap_helper.S which does special handling of LR when
the interrupt came from secure. The LR value is stored to memory, and
put back into LR when swapping back to the relevant thread.

Also, add special handling of FP state when switching from secure to
non-secure, since we don't know whether the original non-secure thread
(which called a secure service) was using FP registers, so we always
store them, just in case.

Signed-off-by: Øyvind Rønningstad <oyvind.ronningstad@nordicsemi.no>

When ARM_NONSECURE_PREEMPTIBLE_SECURE_CALLS is enabled, if FPU is
being used (CONTROL.FPCA == 1), store all FP registers before
entering the secure function, and restore them afterwards.

This is needed if any NS thread or ISR that interrupts the secure
function uses FP registers. If they do, a secure UsageFault occurs
unless this change is applied.

This allows k_sched_lock() and k_sched_unlock() to be dropped when
ARM_NONSECURE_PREEMPTIBLE_SECURE_CALLS is enabled.

Enable ARM_NONSECURE_PREEMPTIBLE_SECURE_CALLS by default when
building TF-M.

Signed-off-by: Øyvind Rønningstad <oyvind.ronningstad@nordicsemi.no>

For testing secure->non-secure thread swapping.
This also tests that the FP context is correctly preserved
when calling a secure function.

Signed-off-by: Øyvind Rønningstad <oyvind.ronningstad@nordicsemi.no>

Add an entry in the release notes regarding the
support for non-blocking secure calls in Zephyr.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>

Decrease the submitted work delay, to ensure that the PSA
crypto operation will be preempted when the work fires. The
modification is required for devices with fast crypto
operations. Also minor corrections to the test ase name,
so it is not the same with the other arm_thread_swap test.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>

Correct thee dt overlays for the STM32 boards, so the Zephyr
image starting address is in accordance with what TF-m expects
it to be.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>