PT_DAR
CHECK_REG(PT_DAR, dar);
unsafe_get_user(regs->dar, &sc->gp_regs[PT_DAR], efault_out);
err |= __get_user(regs->dar, &sc->gp_regs[PT_DAR]);
ucp->uc_mcontext.gp_regs[PT_DAR] = random();
ucp->uc_link->uc_mcontext.gp_regs[PT_DAR] = random();