W^X Transition (5 of 6): Without per-page X



Some cpu lack per-page X
but have a less refined
"range of execution".

We can put a "line" in the
address space: above line
execution does not work

Split code from data:
Move data high, code low.

Data above 512MB
Code below 512MB

Lots of room for the heap


W^X for:
   i386  (powerpc)