Re: [XEN PATCH][for-4.19 v3] xen: Add deviations for MISRA C:2012 Rule 7.1

[Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>]

On 26/10/2023 08:49, Jan Beulich wrote:
> On 26.10.2023 00:34, Stefano Stabellini wrote:
> > On Wed, 25 Oct 2023, Jan Beulich wrote:
> > > On 24.10.2023 22:30, Stefano Stabellini wrote:
> > > > On Tue, 24 Oct 2023, Nicola Vetrini wrote:
> > > > > As specified in rules.rst, these constants can be used
> > > > > in the code.
> > > > >
> > > > > Signed-off-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
> > > > > ---
> > > > > Changes in v2:
> > > > > - replace some SAF deviations with configurations
> > > > > Changes in v3:
> > > > > - refine configurations and justifications
> > > > > ---
> > > > >  automation/eclair_analysis/ECLAIR/deviations.ecl | 10 ++++++----
> > > > >  docs/misra/deviations.rst                        |  5 +++++
> > > > >  docs/misra/safe.json                             |  8 ++++++++
> > > > >  xen/arch/x86/hvm/svm/emulate.c                   |  6 +++---
> > > > >  xen/common/inflate.c                             |  4 ++--
> > > > >  5 files changed, 24 insertions(+), 9 deletions(-)
> > > > >
> > > > > diff --git a/automation/eclair_analysis/ECLAIR/deviations.ecl 
> > > > > b/automation/eclair_analysis/ECLAIR/deviations.ecl
> > > > > index fa56e5c00a27..ea5e0eb1813f 100644
> > > > > --- a/automation/eclair_analysis/ECLAIR/deviations.ecl
> > > > > +++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
> > > > > @@ -85,10 +85,12 @@ 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)$"}
> > > > > +-doc_begin="It is safe to use certain octal constants the way they 
> > > > > are defined in
> > > > > +specifications, manuals, and algorithm descriptions."
> > > > > +-file_tag+={x86_svm_h, "^xen/arch/x86/hvm/svm/svm\\.h$"}
> > > > > +-file_tag+={x86_emulate_c, "^xen/arch/x86/hvm/svm/emulate\\.c$"}
> > > > > +-config=MC3R1.R7.1,reports+={safe, 
> > > > > "any_area(any_loc(any_exp(file(x86_svm_h)&&macro(^INSTR_ENC$))))"}
> > > > > +-config=MC3R1.R7.1,reports+={safe, 
> > > > > "any_area(text(^.*octal-ok.*$)&&any_loc(any_exp(file(x86_emulate_c)&&macro(^MASK_EXTR$))))"}
> > > > >  -doc_end
> > > > >
> > > > >  -doc_begin="Violations in files that maintainers have asked to not 
> > > > > modify in the
> > > > > diff --git a/docs/misra/deviations.rst b/docs/misra/deviations.rst
> > > > > index 8511a189253b..26c6dbbc9ffe 100644
> > > > > --- a/docs/misra/deviations.rst
> > > > > +++ b/docs/misra/deviations.rst
> > > > > @@ -90,6 +90,11 @@ 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.
> > > > I think we should add that these cases have "octal-ok" as a in-code
> > > > comment. Everything else looks OK so this small change could be done 
> > > > on
> > > > commit.
> > > But that needs wording carefully, as it doesn't hold across the 
> > > board:
> > > Right now relevant MASK_EXTR() uses gain such comments, but 
> > > INSTR_ENC()
> > > ones (deliberately) don't.
> > What about:
> >
> > * - R7.1
> >   - It is safe to use certain octal constants the way they are defined
> >     in specifications, manuals, and algorithm descriptions. Such 
> > places
> >     are marked safe with a /* octal-ok */ in-code comment, or with a 
> > SAF
> >     comment (see safe.json).
> Fine with me.
>
> Jan
Ok, I'll update the deviation record.

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