The implementation of try_arch_atomic_exchange does not correctly pass
RELEASE memory ordering (or stronger) to the exchange operation.
To acknowledge this, try_arch_atomic_exchange is replaced by a relaxed
try_arch_atomic_exchange_rlx which does not apply any memory ordering.
Instead, the memory ordering is now added manually by
sel4_atomic_exchange. This provides better latency for interrupts as no
barriers are evoked inside the loop which performs the relaxed exchange
and checks for interrupts.
Furthermore, the new manual application of barriers ensures the memory
ordering passed to sel4_atomic_exchange.
Signed-off-by: jonas <s9joober@gmail.com>
8ba22dcdc5