powerpc PROT_EXEC best-effort


powerpc lacks per-page X bit

Hardware feature:  16 256MB segments, these have an X bit

architecture has a near-access offset limit of 256MB (pic vs PIC)

Solution: Make every 2nd segment X or not-X

Link each shared object to have 256MB gap between code & data

Map code & data segments from program, ld.so, and library over
segment boundaries

Result: W^X on powerpc

Might be in 3.4