[PATCH] off_t: fix register pair calculation for 64-bit case

[Yury Norov]

On Fri, Jun 24, 2016 at 05:30:32AM -0700, H.J. Lu wrote:
> On Fri, Jun 24, 2016 at 5:23 AM, Yury Norov <ynorov@caviumnetworks.com> wrote:
> > There are 3 syscall wrappers under sysdeps/unix/sysv/linux that
> > calculate register pair for off_t like this:
> >         __LONG_LONG_PAIR (offset >> 31, offset)
> >
> > While it works for 32-bit off_t, new 32-bit APIs that use 64-bit
> > off_t will be broken with it. This patch redirects affected syscalls
> > to their 64-bit versions. It also saves few instructions and symbols
> > in glibc, as 32-bit syscall wrappers are not generated anymore.
> 
> If you have 64-bit register, should you use wordsize-64, like
> 
> sysdeps/unix/sysv/linux/wordsize-64
> 
> H.J.

Sometimes it's not possible. AARCh64/ILP32 requires to pass 64-bit
parameters as pair. (this is one of two options for ILP32 that is
under discussion)