It looks that _last_Java_sp is additionally used as acquire/release flag that guards the rest of the state. Yet, the coding in javaFrameAnchor_aarch64.hpp is incorrect at least in one place:

    _last_Java_fp = src->_last_Java_fp;
    _last_Java_pc = src->_last_Java_pc;
    // Must be last so profiler will always see valid frame if has_last_frame() is true
    _last_Java_sp = src->_last_Java_sp;

There should be OrderAccess::release() where the comment suggesting the ordering constraint actually is. Additionally, it has to be matched with OrderAccess::acquire() before _last_Java_sp reads.

Example fix:
 https://github.com/openjdk/jdk/compare/master...shipilev:JDK-8253611-aarch64-javaframeanchor