modules: Load module sections at page-aligned addresses

modules: Load module sections at page-aligned addresses

Currently we load module sections at whatever alignment gcc+ld happened
to dump into the ELF section header which is often less then the page
size. Since NX protections are page based this alignment must be rounded
up to page size on platforms supporting NX protections. This patch
switches EFI platforms to load module sections at 4 KiB page-aligned
addresses. It then changes the allocation size computation and the
loader code in grub_dl_load_segments() to align the locations and sizes
up to these boundaries and fills any added padding with zeros. All of
this happens before relocations are applied, so the relocations factor
that in with no change.

Signed-off-by: Peter Jones <pjones@redhat.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Jan Setje-Eilers <jan.setjeeilers@oracle.com>
Signed-off-by: Mate Kukri <mate.kukri@canonical.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>