Re: [PATCH v15 05/23] tools: include: Add kbuild.h for assembly structure offsets

[Xiaoyao Li <xiaoyao.li@intel.com>]

On 10/2/2026 3:37 AM, Lisa Wang wrote:
> From: Sagi Shahar <sagis@google.com>
> 
> Add the Kbuild macros needed to enable the filechk_offsets mechanism to
> generate C header files containing structure member offset information.
> 
> Tools depending on assembly code that operate on structures have to
> hardcode the offsets of structure members. The Kbuild infrastructure
> can instead generate C header files with these offsets automatically,
> allowing them to be included in assembly code as symbolic constants.
> 
> For example, the TDX guest boot code requires access to parameters
> passed in the C structure (struct td_boot_parameters). This header
> provides the macros needed to extract these offsets from C code and
> expose them to assembly, ensuring the two remain synchronized.
> 
> Signed-off-by: Sagi Shahar <sagis@google.com>
> Signed-off-by: Lisa Wang <wyihan@google.com>
> Reviewed-by: Ira Weiny <ira.weiny@intel.com>
> Reviewed-by: Ackerley Tng <ackerleytng@google.com>
> Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>

Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>

> ---
>  tools/include/linux/kbuild.h | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/tools/include/linux/kbuild.h b/tools/include/linux/kbuild.h
> new file mode 100644
> index 000000000000..957fd55cd159
> --- /dev/null
> +++ b/tools/include/linux/kbuild.h
> @@ -0,0 +1,11 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __TOOLS_LINUX_KBUILD_H
> +#define __TOOLS_LINUX_KBUILD_H
> +
> +#define DEFINE(sym, val) \
> +	asm volatile("\n.ascii \"->" #sym " %0 " #val "\"" : : "i" (val))
> +
> +#define OFFSET(sym, str, mem) \
> +	DEFINE(sym, __builtin_offsetof(struct str, mem))
> +
> +#endif /* __TOOLS_LINUX_KBUILD_H */
>