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




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

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

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

Data above 512MB
Code below 512MB

Code and data are 512MB apart

Lots of room for the heap

W^X for:

   i386  (powerpc)