• Heiko Carstens's avatar
    s390/bpf,jit: fix 32 bit divisions, use unsigned divide instructions · 3af57f78
    Heiko Carstens authored
    The s390 bpf jit compiler emits the signed divide instructions "dr" and "d"
    for unsigned divisions.
    This can cause problems: the dividend will be zero extended to a 64 bit value
    and the divisor is the 32 bit signed value as specified A or X accumulator,
    even though A and X are supposed to be treated as unsigned values.
    The divide instrunctions will generate an exception if the result cannot be
    expressed with a 32 bit signed value.
    This is the case if e.g. the dividend is 0xffffffff and the divisor either 1
    or also 0xffffffff (signed: -1).
    To avoid all these issues simply use unsigned divide instructions.
    Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>