Comment 1 for bug 1906295

QEMU's load/store exclusive implementation is known to not be architecturally compliant. Most notably, it works on virtual addresses and the architecture specifies that exclusives are supposed to work on physical addresses. We provide a "good enough for what real code (not weird test cases) needs" implementation.

However, in this specific case, we're within the architectural requirements. In the ARMv8A Arm ARM (DDI0487F.c) the pseudocode AArch32.ExclusiveMonitorsPass() function has this comment:

// It is IMPLEMENTATION DEFINED whether the detection of memory aborts happens
// before or after the check on the local Exclusives monitor. As a result a failure
// of the local monitor can occur on some implementations even if the memory
// access would give a memory about.

In other words, it's up to the implementation whether it detects and reports the invalid address first. QEMU's implementation chooses not to.