On Mon, 27 Mar 2017 18:59:04 +0100 Peter Maydell <peter.mayd...@linaro.org> wrote:
> For a packed struct like 'P9Hdr' the fields within it may not be > aligned as much as the natural alignment for their types. This means > it is not valid to pass the address of such a field to a function > like le32_to_cpus() which operate on uint32_t* and assume alignment. > Doing this results in a SIGBUS on hosts like SPARC which have strict > alignment requirements. > > Use ldl_le_p() instead, which is specified to correctly handle > unaligned pointers. > > Signed-off-by: Peter Maydell <peter.mayd...@linaro.org> > --- Reviewed-by: Greg Kurz <gr...@kaod.org> I'll apply this to my tree and send a pull request tomorrow. Cheers. -- Greg > Sadly gcc doesn't warn about this: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=51628 > clang supposedly was fixed to do so: > https://bugs.llvm.org//show_bug.cgi?id=22821 > but I think that commit was reverted without the bug being > reopened; at least my clang doesn't have that warning flag. > --- > tests/virtio-9p-test.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/tests/virtio-9p-test.c b/tests/virtio-9p-test.c > index 43a1ad8..ad33d96 100644 > --- a/tests/virtio-9p-test.c > +++ b/tests/virtio-9p-test.c > @@ -256,8 +256,8 @@ static void v9fs_req_recv(P9Req *req, uint8_t id) > qvirtio_wait_queue_isr(v9p->dev, v9p->vq, 1000 * 1000); > > v9fs_memread(req, &hdr, 7); > - le32_to_cpus(&hdr.size); > - le16_to_cpus(&hdr.tag); > + hdr.size = ldl_le_p(&hdr.size); > + hdr.tag = lduw_le_p(&hdr.tag); > if (hdr.size >= 7) { > break; > }
pgpPg_6kMUAvS.pgp
Description: OpenPGP digital signature
