[PATCH v2] Allow exec on 32-bit from readable, non-exec pages, with a warning.

[Paul Mackerras]

Scott Wood writes:

> In older versions of glibc (through 2.3), the dynamic linker executes a
> small amount of code from the data segment, which is not marked as
> executable.  A recent change (commit 9ba4ace39fdfe22268daca9f28c5df384ae462cf)
> stops this from working; there should be a deprecation period before
> older glibc versions stop working.

Actually I see no good reason to enforce no-exec at all if we can't do
it consistently.  And if we're not going to enforce it then there is
no point whinging about it.

When I applied Segher's original patch I thought that we had the
read-implies-exec stuff enabled for the affected CPUs, but it turns
out we don't.  (We only have that stuff turned on for 32-bit processes
on 64-bit cpus - see elf_read_implies_exec in include/asm-powerpc/elf.h.)

Paul.