Re: [PATCH v4 1/2] kho: add KHOSER_COPY_TYPE(UN)SAFE for phys copy

On Mon, 22 Jun 2026 22:57:35 +0000, Tarun Sahu <[email protected]> wrote:
> Adding KHOSER_COPY_TYPESAFE and KHOSER_COPY_TYPEUNSAFE to copy one
> serializeable pointer to another. It basically allows copy of phys val
> of the serializeable pointer.

Please update the commit message :)

>
>
> diff --git a/include/linux/kho/abi/kexec_handover.h b/include/linux/kho/abi/kexec_handover.h
> index 5e2eb8519bda..c1b61d875dcc 100644
> --- a/include/linux/kho/abi/kexec_handover.h
> +++ b/include/linux/kho/abi/kexec_handover.h
> @@ -139,6 +139,17 @@
>  		(typeof((s).ptr))((s).phys ? phys_to_virt((s).phys) : NULL); \
>  	})
>  
> +/* Copies one serializable pointer to another. */
> +#define KHOSER_COPY_PTR(dest, src) \
> +	({ \
> +		static_assert( \
> +			__builtin_types_compatible_p(typeof((dest).ptr), typeof((src).ptr)) || \
> +			__builtin_types_compatible_p(typeof((dest).ptr), void *) || \
> +			__builtin_types_compatible_p(typeof((src).ptr), void *), \
> +			"pointer type mismatch in KHOSER_COPY_PTR" \
> +		); \
> +		(dest).phys = (src).phys; \
> +	})

I'd suggest declaring local variables for the pointers and verifying
their compatibility. E.g.

	({								\
		typeof((dest).ptr) __dst;				\
		typeof((src).ptr) __src;				\
		static_assert(						\
			__builtin_types_compatible_p(__dst, __src)) ||	\
			__builtin_types_compatible_p(__dst, void *) ||	\
			__builtin_types_compatible_p(__src, void *),	\
			"pointer type mismatch in KHOSER_COPY_PTR"	\
		); \
		(dest).phys = (src).phys; \
	})

IMO it's easier to decipher this way.

-- 
Sincerely yours,
Mike.