The Xen domctl ABI currently relies on the union containing a field with
alignment of 8.
32bit projects which only copy the used subset of functionality end up with an
ABI breakage if they don't have at least one uint64_aligned_t field copied.
Insert explicit padding, and some build assertions to ensure it never changes
moving forwards.
Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
---
CC: George Dunlap <george.dun...@eu.citrix.com>
CC: Ian Jackson <ian.jack...@citrix.com>
CC: Jan Beulich <jbeul...@suse.com>
CC: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
CC: Stefano Stabellini <sstabell...@kernel.org>
CC: Wei Liu <w...@xen.org>
CC: Julien Grall <jul...@xen.org>
Further proof that C isn't an appropriate way to desribe an ABI...
---
xen/common/domctl.c | 8 ++++++++
xen/include/public/domctl.h | 1 +
2 files changed, 9 insertions(+)
diff --git a/xen/common/domctl.c b/xen/common/domctl.c
index a69b3b59a8..20ef8399bd 100644
--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -959,6 +959,14 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t)
u_domctl)
return ret;
}
+static void __init __maybe_unused build_assertions(void)
+{
+ struct xen_domctl d;
+
+ BUILD_BUG_ON(sizeof(d) != 16 /* header */ + 128 /* union */);
+ BUILD_BUG_ON(offsetof(typeof(d), u) != 16);
+}
+
/*
* Local variables:
* mode: C
diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index 59bdc28c89..9464a9058a 100644
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -1222,6 +1222,7 @@ struct xen_domctl {
#define XEN_DOMCTL_gdbsx_domstatus 1003
uint32_t interface_version; /* XEN_DOMCTL_INTERFACE_VERSION */
domid_t domain;
+ uint16_t _pad[3];
union {
struct xen_domctl_createdomain createdomain;
struct xen_domctl_getdomaininfo getdomaininfo;
--
2.11.0
