"Secondly, it turns out that, contrary to all my expectations, the executable bit can be dropped from the p_flags field. It turns out that the readable and executable bits are redundant: either one will imply the other."

Wonder if this will still work with processors that use NX-bits, or if that is set outside the ELF header.

Can't entirely tell since there seems to be some kind of backwards compatibility hack on x86 for legacy apps that might have been unaware of the potential for NX: https://lwn.net/Articles/94068/