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

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 22/05/2026 11:24 am, Roger Pau Monné wrote:
> 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.

Yes.  Teddy has a patch out to fix that, and this patch needs rebasing
over it.

~Andrew