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

[Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>]

On 19/10/2023 17:57, Jan Beulich wrote:
> On 19.10.2023 13:04, Nicola Vetrini wrote:
> > --- a/automation/eclair_analysis/ECLAIR/deviations.ecl
> > +++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
> > @@ -85,10 +85,10 @@ conform to the directive."
> >  # Series 7.
> >  #
> >
> > --doc_begin="Usage of the following constants is safe, since they are 
> > given as-is
> > -in the inflate algorithm specification and there is therefore no risk 
> > of them
> > -being interpreted as decimal constants."
> > --config=MC3R1.R7.1,literals={safe, 
> > "^0(007|37|070|213|236|300|321|330|331|332|333|334|335|337|371)$"}
> > +-doc_begin="Octal constants used as arguments to macro INSTR_ENC or 
> > MASK_EXTR
> > +can be used, because they appear as is in specifications, manuals, 
> > and
> > +algorithm descriptions."
> > +-config=MC3R1.R7.1,reports+={safe, 
> > "any_area(any_loc(any_exp(macro(^(INSTR_ENC|MASK_EXTR)$))))"}
> INSTR_ENC() is a local macro in x86'es AMD SVM code. A macro of the 
> same
> name could imo be introduced without issues in, say, Arm code. The 
> above
> would then needlessly suppress findings there, aiui.
>
> MASK_EXTR() otoh is a global macro which ise used for various purposes.
> Excluding checking there is imo going too far, too.
I should have thought about it; I can simply enforce the deviation to 
additionally match
only a specific file for each of the macros.

> > --- a/docs/misra/deviations.rst
> > +++ b/docs/misra/deviations.rst
> > @@ -90,6 +90,12 @@ Deviations related to MISRA C:2012 Rules:
> >           - __emulate_2op and __emulate_2op_nobyte
> >           - read_debugreg and write_debugreg
> >
> > +   * - R7.1
> > +     - It is safe to use certain octal constants the way they are 
> > defined in
> > +       specifications, manuals, and algorithm descriptions as 
> > arguments to
> > +       macros 'INSTR_ENC' and 'MASK_EXTR'.
> > +     - Tagged as `safe` for ECLAIR.
> Similarly this wording is imo inappropriate, while ...
I tried to be a bit more specific about what is actually being deviated, 
on the assumption
that the maintainers and contributors would find it more useful than 
parsing ecl files, but
if you prefer it to be more general, no problem.

> > --- a/docs/misra/safe.json
> > +++ b/docs/misra/safe.json
> > @@ -20,6 +20,14 @@
> >          },
> >          {
> >              "id": "SAF-2-safe",
> > +            "analyser": {
> > +                "eclair": "MC3R1.R7.1"
> > +            },
> > +            "name": "Rule 7.1: constants defined in specifications, 
> > manuals, and algorithm descriptions",
> > +            "text": "It is safe to use certain octal constants the 
> > way they are defined in specifications, manuals, and algorithm 
> > descriptions."
> > +        },
> ... this reads good to me.
>
> Jan
--
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)