For the case where the source is not aligned modulo 8
we don't use load-twins to suck the data in and this
kills performance since normal loads allocate in the
L1 cache (unlike load-twin) and thus big memcpys swipe
the entire L1 D-cache.

We need to allocate a register window to implement this
properly, but that actually simplifies a lot of things
as a nice side-effect.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The manual says that it is required and we actually have crash reports
where loads see stale data due to not having membars here.

In one case the networking does:

	memset(skb, 0, offsetof(struct sk_buff, truesize));

and then some code later checks skb->nohdr for zero, but it's still
the value that was there before the memset().

Note that arch/sparc64/lib/xor.S already got this right.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We need to restore the %asi register properly.
For the kernel this means get_fs(), for user this
means ASI_PNF.

Also, NGcopy_to_user.S was including U3memcpy.S instead
of NGmemcpy.S, oops :-)
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>