PATCH: Add x32 arch_prctl support

[Roland McGrath]

> The goes back to user uint32_t vs kernel uint64_t:
> 
> http://sourceware.org/ml/libc-alpha/2012-05/msg01519.html
> 
> The difference is movq vs movl.  There is no need for movq
> since x32 will only pass unsigned 32-bit value to kernel.

I see.  That one byte in a rarely-used call is not reason enough to
make the code uglier.

> Thanks.  But since x32 kernel takes PTRACE_ARCH_PRCTL, I
> still need x32 ptrace to either handle it properly or set EINVAL
> when PTRACE_ARCH_PRCTL is passed.

It was my proposal that the kernel be changed to refuse PTRACE_ARCH_PRCTL
in a ptrace call made from an x32 task.


Thanks,
Roland