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

[Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>]

> > > > 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)