Re: [Qemu-devel] [PATCH 01/13] linux-user: Use memcpy in get_user/put_user.

[Peter Maydell]

On 17 September 2012 16:28, Richard Henderson <address@hidden> wrote:
> Not sure whether this is a gcc bug, but on sparc we wind up
> trying to use std to an unaligned address.  The patch does
> work around the problem.
>
> Signed-off-by: Richard Henderson <address@hidden>

As far as the code is concerned:
Reviewed-by: Peter Maydell <address@hidden>

but please rewrite the commit message to be more sure of itself :-)

Specifically, this is required because the guest's alignment
requirements may be laxer than those of the host, so we can't
take a hptr for a 16/32/64 bit type (which only has the alignment
restrictions of the guest) and do a gcc pointer dereference on it
(which may assume the alignment restrictions of the host).

Does anybody know the semantics of the kernel's copy_from_user()?
Does it fail on misaligned userspace structs or does it allow
them?

-- PMM