Re: [XEN PATCH v3] xen: replace occurrences of SAF-1-safe with asmlinkage attribute

[Jan Beulich <jbeulich@xxxxxxxx>]

On 16.11.2023 10:08, Nicola Vetrini wrote:
> The comment-based justifications for MISRA C:2012 Rule 8.4 are replaced
> by the asmlinkage pseudo-attribute, for the sake of uniformity.
> 
> Add missing 'xen/compiler.h' #include-s where needed.
> 
> The text in docs/misra/deviations.rst and docs/misra/safe.json
> is modified to reflect this change.
> 
> Signed-off-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
> ---
> This patch should be applied after patch 2 of this series.
> The request made by Julien to update the wording is
> contained in the present patch.

Along with this request he supplied you with an ack. Did you drop that
for a particular reason, or did you simply forget to record it here?

> --- a/xen/arch/x86/boot/reloc.c
> +++ b/xen/arch/x86/boot/reloc.c
> @@ -28,6 +28,7 @@ asm (
>  
>  #include "defs.h"
>  
> +#include <xen/compiler.h>
>  #include <xen/kconfig.h>
>  #include <xen/multiboot.h>
>  #include <xen/multiboot2.h>
> @@ -348,9 +349,8 @@ static multiboot_info_t *mbi2_reloc(uint32_t mbi_in, 
> uint32_t video_out)
>      return mbi_out;
>  }
>  
> -/* SAF-1-safe */
> -void *__stdcall reloc(uint32_t magic, uint32_t in, uint32_t trampoline,
> -                      uint32_t video_info)
> +void *asmlinkage __stdcall reloc(uint32_t magic, uint32_t in,
> +                                 uint32_t trampoline, uint32_t video_info)
>  {

One purpose of asmlinkage is to possibly alter the default C calling convention
to some more easy to use in assembly code. At least over a period of time Linux
for example used that on ix86. If we decided to do something like this, there
would be a collision with __stdcall. Hence I'm not convinced we can put
asmlinkage here. At which point the complete removal of SAF-1-safe also would
need dropping.

> --- a/xen/common/efi/boot.c
> +++ b/xen/common/efi/boot.c
> @@ -1254,9 +1254,8 @@ static void __init efi_exit_boot(EFI_HANDLE 
> ImageHandle, EFI_SYSTEM_TABLE *Syste
>      efi_fw_vendor = (void *)efi_fw_vendor + DIRECTMAP_VIRT_START;
>  }
>  
> -/* SAF-1-safe */
> -void EFIAPI __init noreturn efi_start(EFI_HANDLE ImageHandle,
> -                                      EFI_SYSTEM_TABLE *SystemTable)
> +void asmlinkage EFIAPI __init noreturn efi_start(EFI_HANDLE ImageHandle,
> +                                                 EFI_SYSTEM_TABLE 
> *SystemTable)

Same here wrt EFIAPI, as that also alters the calling convention.

Jan