Memory protection keys

One application use that may benefit from cheap changing of protections is garbage collection. There are schemes where you want to catch it if additional pointers from old to new memory are written. If such writes into old memory are rare, catching that with memory protection is more efficient than software checking of writes. I am not sure if the keys described in the article are really useful for that, it has been some time since I read garbage collection papers.

Another application use may be hardening JIT compiler-generated code against vulnerabilities. Last year I heard a presentation where the JIT compiler was put in a separate process to get different protections for the JIT compiler than for the execution. The protection keys may be an easier way to get the same protection.