Re: [PATCH V3 (resend) 08/19] xen/x86: Add build assertion for fixmap entries

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Mon, May 13, 2024 at 01:40:35PM +0000, Elias El Yandouzi wrote:
> The early fixed addresses must all fit into the static L1 table.
> Introduce a build assertion to this end.
> 
> Signed-off-by: Elias El Yandouzi <eliasely@xxxxxxxxxx>
> 
> ----
> 
>      Changes in v2:
>          * New patch
> 
> diff --git a/xen/arch/x86/include/asm/fixmap.h 
> b/xen/arch/x86/include/asm/fixmap.h
> index a7ac365fc6..904bee0480 100644
> --- a/xen/arch/x86/include/asm/fixmap.h
> +++ b/xen/arch/x86/include/asm/fixmap.h
> @@ -77,6 +77,11 @@ enum fixed_addresses {
>  #define FIXADDR_SIZE  (__end_of_fixed_addresses << PAGE_SHIFT)
>  #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
>  
> +static inline void fixaddr_build_assertion(void)
> +{
> +    BUILD_BUG_ON(FIX_PMAP_END > L1_PAGETABLE_ENTRIES - 1);
> +}

Just introduce the BUILD_BUG_ON somewhere else, no need for a new
function just for this.

Adding the BUILD_BUG_ON() to pmap_map() would be perfectly fine.

Thanks, Roger.