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

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

>>>> 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.

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