> Write XOR execute (W^X)
> Apple Silicon Macs will enforce a restriction called “write XOR execute” (W^X). This means that chunks of memory will be designated as writable, or as executable, but never as both at the same time. Many macOS apps contain performance optimization programs that require memory to be both writable and executable, but this can lead to serious security issues. By enforcing W^X, Apple will harden Mac security at the memory level. App developers, however, won’t be left out in the cold — if they still need those optimization programs for their apps, they can use a new macOS API that provides a way to switch between write and execute permissions quickly and safely.
And the nature of W^X - https://en.wikipedia.org/wiki/W%5EX
> W^X ("write xor execute", pronounced W xor X) is a security feature in operating systems and virtual machines. It is a memory protection policy whereby every page in a process's or kernel's address space may be either writable or executable, but not both. Without such protection, a program can write (as data "W") CPU instructions in an area of memory intended for data and then run (as executable "X"; or read-execute "RX") those instructions. This can be dangerous if the writer of the memory is malicious. W^X is the Unix-like terminology for a strict use of the general concept of executable space protection, controlled via the mprotect system call.
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See also Porting just-in-time compilers to Apple silicon - https://developer.apple.com/documentation/apple-silicon/port...
And W^X now mandatory in OpenBSD (8 years ago : https://news.ycombinator.com/item?id=11789169 )
