On some variants of the Fujitsu-A64FX cores ver(1.0, 1.1),
memory accesses may cause undefined fault (Data abort, DFSC=0b111111).
This problem will be fixed by next version of Fujitsu-A64FX.
This fault occurs under a specific hardware condition
when a load/store instruction perform an address translation using:
case-1 TTBR0_EL1 with TCR_EL1.NFD0 == 1.
case-2 TTBR0_EL2 with TCR_EL2.NFD0 == 1.
case-3 TTBR1_EL1 with TCR_EL1.NFD1 == 1.
case-4 TTBR1_EL2 with TCR_EL2.NFD1 == 1.
And this fault occurs completely spurious.
Since TCR_ELx.NFD1 is set to '1' at the kernel in versions
past 4.17, the case-3 or case-4 may happen.