Build fails with gcc 9:

crypto/block-luks.c:689:18: error: taking address of packed member of ‘struct QCryptoBlockLUKSHeader’ may result in an unaligned pointer value [-Werror=address-of-packed-member]
  689 |     be32_to_cpus(&luks->header.payload_offset);
      |                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
crypto/block-luks.c:690:18: error: taking address of packed member of ‘struct QCryptoBlockLUKSHeader’ may result in an unaligned pointer value [-Werror=address-of-packed-member]
  690 |     be32_to_cpus(&luks->header.key_bytes);
      |                  ^~~~~~~~~~~~~~~~~~~~~~~
crypto/block-luks.c:691:18: error: taking address of packed member of ‘struct QCryptoBlockLUKSHeader’ may result in an unaligned pointer value [-Werror=address-of-packed-member]
  691 |     be32_to_cpus(&luks->header.master_key_iterations);
      |                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

... a bunch of similar errors...

crypto/block-luks.c:1288:22: error: taking address of packed member of ‘struct QCryptoBlockLUKSKeySlot’ may result in an unaligned pointer value [-Werror=address-of-packed-member]
 1288 |         be32_to_cpus(&luks->header.key_slots[i].stripes);
      |                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

All members of the QCryptoBlockLUKSKeySlot and QCryptoBlockLUKSHeader are
naturally aligned and we already check at build time there isn't any
unwanted padding. Drop the QEMU_PACKED attribute.

Signed-off-by: Greg Kurz <groug@kaod.org>
---
 crypto/block-luks.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/crypto/block-luks.c b/crypto/block-luks.c
index 6bac79c3ab6b..5a69b3ce74d3 100644
--- a/crypto/block-luks.c
+++ b/crypto/block-luks.c
@@ -146,7 +146,7 @@ struct QCryptoBlockLUKSKeySlot {
     uint32_t key_offset;
     /* number of anti-forensic stripes */
     uint32_t stripes;
-} QEMU_PACKED;
+};
 
 QEMU_BUILD_BUG_ON(sizeof(struct QCryptoBlockLUKSKeySlot) != 48);
 
@@ -191,7 +191,7 @@ struct QCryptoBlockLUKSHeader {
 
     /* key slots */
     QCryptoBlockLUKSKeySlot key_slots[QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS];
-} QEMU_PACKED;
+};
 
 QEMU_BUILD_BUG_ON(sizeof(struct QCryptoBlockLUKSHeader) != 592);
 

On 2/28/19 9:06 AM, Greg Kurz wrote:
> Build fails with gcc 9:
> 
> crypto/block-luks.c:689:18: error: taking address of packed member of ‘struct QCryptoBlockLUKSHeader’ may result in an unaligned pointer value [-Werror=address-of-packed-member]
>   689 |     be32_to_cpus(&luks->header.payload_offset);
>       |                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~

> 
> All members of the QCryptoBlockLUKSKeySlot and QCryptoBlockLUKSHeader are
> naturally aligned and we already check at build time there isn't any
> unwanted padding. Drop the QEMU_PACKED attribute.
> 
> Signed-off-by: Greg Kurz <groug@kaod.org>
> ---
>  crypto/block-luks.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

On Thu, Feb 28, 2019 at 04:06:06PM +0100, Greg Kurz wrote:
> Build fails with gcc 9:
> 
> crypto/block-luks.c:689:18: error: taking address of packed member of ‘struct QCryptoBlockLUKSHeader’ may result in an unaligned pointer value [-Werror=address-of-packed-member]
>   689 |     be32_to_cpus(&luks->header.payload_offset);
>       |                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
> crypto/block-luks.c:690:18: error: taking address of packed member of ‘struct QCryptoBlockLUKSHeader’ may result in an unaligned pointer value [-Werror=address-of-packed-member]
>   690 |     be32_to_cpus(&luks->header.key_bytes);
>       |                  ^~~~~~~~~~~~~~~~~~~~~~~
> crypto/block-luks.c:691:18: error: taking address of packed member of ‘struct QCryptoBlockLUKSHeader’ may result in an unaligned pointer value [-Werror=address-of-packed-member]
>   691 |     be32_to_cpus(&luks->header.master_key_iterations);
>       |                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> ... a bunch of similar errors...
> 
> crypto/block-luks.c:1288:22: error: taking address of packed member of ‘struct QCryptoBlockLUKSKeySlot’ may result in an unaligned pointer value [-Werror=address-of-packed-member]
>  1288 |         be32_to_cpus(&luks->header.key_slots[i].stripes);
>       |                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> cc1: all warnings being treated as errors
> 
> All members of the QCryptoBlockLUKSKeySlot and QCryptoBlockLUKSHeader are
> naturally aligned and we already check at build time there isn't any
> unwanted padding. Drop the QEMU_PACKED attribute.
> 
> Signed-off-by: Greg Kurz <groug@kaod.org>
> ---
>  crypto/block-luks.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

I'll queue this one.


Regards,
Daniel
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