Re: [PATCH mig] Change complex_align_of to be sizeof(uintptr_t)

[Samuel Thibault]

Applied, thanks!

Flavio Cruz, le dim. 19 févr. 2023 18:11:05 -0500, a ecrit:
> By using uintptr_t, we ensure that all 64 bit stubs are free of
> undefined behavior since we support up to 8-byte alignment. This works
> fine given that Mig will type check types that have higher alignment
> requirements through the use of _Static_assert.
> 
> This even works for a 64 bit kernel / 32 bit user land since we can use
> mig64 to build stubs for the 8-byte aligned kernel stubs and existing 32
> bit mig to build the old user side stubs. Pragma is no longer required as we 
> take
> advantage of the compiler to drive the alignment and avoid undefined
> behavior.
> ---
>  cpu.sym | 2 +-
>  utils.c | 2 --
>  2 files changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/cpu.sym b/cpu.sym
> index 39ae712..bee12f0 100644
> --- a/cpu.sym
> +++ b/cpu.sym
> @@ -95,7 +95,7 @@ expr MACH_MSG_TYPE_POLYMORPHIC
>  
>  
>  /* Types used in interfaces */
> -expr sizeof(natural_t)                       desired_complex_alignof
> +expr sizeof(uintptr_t)                       desired_complex_alignof
>  expr sizeof(void*)                   sizeof_pointer
>  expr sizeof(char)                    sizeof_char
>  expr sizeof(short)                   sizeof_short
> diff --git a/utils.c b/utils.c
> index f2f45f6..419105a 100644
> --- a/utils.c
> +++ b/utils.c
> @@ -342,12 +342,10 @@ void
>  WriteStructDecl(FILE *file, const argument_t *args, write_list_fn_t *func,
>               u_int mask, const char *name)
>  {
> -    fprintf(file, "#pragma pack(push,%d)\n", complex_alignof);
>      fprintf(file, "\ttypedef struct {\n");
>      fprintf(file, "\t\tmach_msg_header_t Head;\n");
>      WriteList(file, args, func, mask, "\n", "\n");
>      fprintf(file, "\t} %s;\n", name);
> -    fprintf(file, "#pragma pack(pop)\n");
>      fprintf(file, "\n");
>  }
>  
> -- 
> 2.39.1
> 
> 

-- 
Samuel
---
Pour une évaluation indépendante, transparente et rigoureuse !
Je soutiens la Commission d'Évaluation de l'Inria.