Re: [PATCH 2/5] x86/PV: rename a local variable in pv_emulate_gate_op()

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

On Wed, May 13, 2026 at 01:44:47PM +0200, Jan Beulich wrote:
> ... shadowing a function scope one, thus violating Misra C:2012 rule 5.3
> ("An identifier declared in an inner scope shall not hide an identifier
> declared in an outer scope"). No difference in generated code.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> ---
> Technically, as the outer scope "rc" isn't used again later, we could
> simply drop the inner decl. That seemed more error prone to me, though.
> 
> --- a/xen/arch/x86/pv/emul-gate-op.c
> +++ b/xen/arch/x86/pv/emul-gate-op.c
> @@ -286,16 +286,16 @@ void pv_emulate_gate_op(struct cpu_user_
>      if ( !jump )
>      {
>          unsigned int ss, esp, *stkp;
> -        int rc;
> +        int left;
>  #define push(item) do \
>          { \
>              --stkp; \
>              esp -= 4; \
> -            rc = __put_guest(item, stkp); \
> -            if ( rc ) \
> +            left = __put_guest(item, stkp); \
> +            if ( left ) \
>              { \
>                  pv_inject_page_fault(PFEC_write_access, \
> -                                     (unsigned long)(stkp + 1) - rc); \
> +                                     (unsigned long)(stkp + 1) - left); \
>                  return; \
>              } \
>          } while ( 0 )
> @@ -359,10 +359,11 @@ void pv_emulate_gate_op(struct cpu_user_
>                      unsigned int parm;
>  
>                      --ustkp;
> -                    rc = __get_guest(parm, ustkp);
> -                    if ( rc )
> +                    left = __get_guest(parm, ustkp);
> +                    if ( left )
>                      {
> -                        pv_inject_page_fault(0, (unsigned long)(ustkp + 1) - 
> rc);
> +                        pv_inject_page_fault(0,
> +                                             (unsigned long)(ustkp + 1) - 
> left);

__{put,get}_guest() return -EFAULT on error, and hence the
addition/subtraction here is wrong AFAICT.

Thanks, Roger.