LINUX_CSIGNAL
sig = flags & LINUX_CSIGNAL;
val = (unsigned)flags & ~LINUX_CSIGNAL;
.flags = (lower_32_bits(args->flags) & ~LINUX_CSIGNAL),
.exit_signal = (lower_32_bits(args->flags) & LINUX_CSIGNAL),
if ((uca->flags & (LINUX_CLONE_DETACHED | LINUX_CSIGNAL)) != 0)
if ((uca->exit_signal & ~(uint64_t)LINUX_CSIGNAL) != 0)