Re: [XEN PATCH][for-4.19 v2] xen: Add SAF deviations for MISRA C:2012 Rule 7.1

[Nicola Vetrini <nicola.vetrini@bugseng.com>]

On 23/10/2023 10:47, Jan Beulich wrote:
> On 23.10.2023 10:44, Nicola Vetrini wrote:
>> 
>>>>>> 3. an use of MASK_EXTR() in x86/hvm/svm/emulate.c appears, with
>>>>>> octal
>>>>>>     constants in the expansion. This will be deviated;
>>>>> 
>>>>> This is what I'm concerned of: How do you know up front whether 
>>>>> such
>>>>> new
>>>>> uses want deviating?
>>>> 
>>>> I understand you concern now. I can argue that all the macros in 
>>>> that
>>>> table have indeed
>>>> an octal constant in their definition (0 is explicitly allowed by
>>>> MISRA).
>>>> This is also specified in the comment above the INSTR_ENC macro
>>>> definition, therefore any
>>>> new addition should have an octal the second argument to INSTR_ENC.
>>> 
>>> Right, and I previously indicated I agree as far as INSTR_ENC() goes.
>>> What we appear to continue to disagree about is MASK_EXTR().
>>> 
>> 
>> Yeah, sorry. What about
>> 
>> if ( modrm_mod       == MASK_EXTR(instr_modrm, 0300) && /* octal-ok */
>>       (modrm_reg & 7) == MASK_EXTR(instr_modrm, 0070) && /* octal-ok 
>> */
>>       (modrm_rm  & 7) == MASK_EXTR(instr_modrm, 0007) )  /* octal-ok 
>> */
>>              return emul_len;
>> 
>> It does not really fit in the SAF framework, because the deviation is
>> still done with a
>> configuration, but at least it gives some clear indication on how to
>> introduce an octal
>> constant in this file.
> 
> Well, I don't mind the comment, but is the config change then going to
> also match (part of) the comment, i.e. key off of not just MASK_EXTR()?
> 
> Jan

Yes, I added that to my reply.

-- 
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)