Re: [PATCH v3] xen: address violations of MISRA C:2012 Rule 11.8.

[Jan Beulich <jbeulich@xxxxxxxx>]

On 04.12.2023 17:32, Simone Ballarin wrote:
> From: Maria Celeste Cesario <maria.celeste.cesario@xxxxxxxxxxx>
> 
> Remove or amend casts to comply with Rule 11.8.
> 
> Fix violations by adding missing const qualifier in cast.
> Fix violations by removing unnecessary cast.
> Change type of operands from char* to uintptr_t: uintptr_t is
> the appropriate type for memory address operations.
> 
> No functional changes.
> 
> Signed-off-by: Maria Celeste Cesario  <maria.celeste.cesario@xxxxxxxxxxx>
> Signed-off-by: Simone Ballarin  <simone.ballarin@xxxxxxxxxxx>

I consider it good practice to at least briefly say what the rule is
about, so it is clear why certain changes need doing.

> --- a/xen/arch/arm/include/asm/atomic.h
> +++ b/xen/arch/arm/include/asm/atomic.h
> @@ -154,7 +154,7 @@ static always_inline void write_atomic_size(volatile void 
> *p,
>   */
>  static inline int atomic_read(const atomic_t *v)
>  {
> -    return *(volatile int *)&v->counter;
> +    return *(const volatile int *)&v->counter;
>  }

What about PPC's identical code?

> --- a/xen/arch/x86/include/asm/regs.h
> +++ b/xen/arch/x86/include/asm/regs.h
> @@ -6,7 +6,7 @@
>  
>  #define guest_mode(r)                                                        
>  \
>  ({                                                                           
>  \
> -    unsigned long diff = (char *)guest_cpu_user_regs() - (char *)(r);        
>  \
> +    unsigned long diff = (uintptr_t)guest_cpu_user_regs() - (uintptr_t)(r);  
>  \
>      /* Frame pointer must point into current CPU stack. */                   
>  \
>      ASSERT(diff < STACK_SIZE);                                               
>  \
>      /* If not a guest frame, it must be a hypervisor frame. */               
>  \

This part
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>

Jan