Like it has already been done for linux-m68k in JDK-8187227, Zero should also be patched on linux-arm to use compiler built-ins for the atomic functions in hotspot/os_cpu/linux_zero/assembler_linux_zero.cpp.

Since the compiler built-ins for cmpxchg() work exactly like the current ARM-specific implementation in Zero, there is no need anymore to carry our own implementation but rather rely on gcc which helps simplifying the code.