SATP_ASID_MASK
#define cntx2asid(cntx) ((cntx) & SATP_ASID_MASK)
#define cntx2version(cntx) ((cntx) & ~SATP_ASID_MASK)
asid_bits = old | (SATP_ASID_MASK << SATP_ASID_SHIFT);
asid_bits = (csr_read(CSR_SATP) >> SATP_ASID_SHIFT) & SATP_ASID_MASK;