ASSERT_STRUCT_OFFSET allows to assert during the build of the kernel that a field in a struct have an expected offset.
KVM used to have such macro, but there is almost nothing KVM specific in it so move it to build_bug.h, so that it can be used in other places in KVM.
Signed-off-by: Maxim Levitsky mlevitsk@redhat.com --- arch/x86/kvm/vmx/vmcs12.h | 5 ++--- include/linux/build_bug.h | 9 +++++++++ 2 files changed, 11 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmcs12.h b/arch/x86/kvm/vmx/vmcs12.h index 746129ddd5ae02..01936013428b5c 100644 --- a/arch/x86/kvm/vmx/vmcs12.h +++ b/arch/x86/kvm/vmx/vmcs12.h @@ -208,9 +208,8 @@ struct __packed vmcs12 { /* * For save/restore compatibility, the vmcs12 field offsets must not change. */ -#define CHECK_OFFSET(field, loc) \ - BUILD_BUG_ON_MSG(offsetof(struct vmcs12, field) != (loc), \ - "Offset of " #field " in struct vmcs12 has changed.") +#define CHECK_OFFSET(field, loc) \ + ASSERT_STRUCT_OFFSET(struct vmcs12, field, loc)
static inline void vmx_check_vmcs12_offsets(void) { diff --git a/include/linux/build_bug.h b/include/linux/build_bug.h index e3a0be2c90ad98..3aa3640f8c181f 100644 --- a/include/linux/build_bug.h +++ b/include/linux/build_bug.h @@ -77,4 +77,13 @@ #define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr) #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
+ +/* + * Compile time check that field has an expected offset + */ +#define ASSERT_STRUCT_OFFSET(type, field, expected_offset) \ + BUILD_BUG_ON_MSG(offsetof(type, field) != (expected_offset), \ + "Offset of " #field " in " #type " has changed.") + + #endif /* _LINUX_BUILD_BUG_H */