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- From cd22e3c62bdf90babba3bdf1bc2b48e4e2e664d5 Mon Sep 17 00:00:00 2001
- From: Maxim Levitsky <[email protected]>
- Date: Tue, 25 Oct 2022 15:47:27 +0300
- Subject: [PATCH] bug: introduce ASSERT_STRUCT_OFFSET
- 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 <[email protected]>
- ---
- 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 746129ddd5ae..01936013428b 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 e3a0be2c90ad..3aa3640f8c18 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 */
- --
- 2.38.1
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