Re: [XEN PATCH][for-4.19 v6 2/8] x86: add deviation for asm-only functions

[Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>]

On 2023-11-02 14:27, Jan Beulich wrote:
> On 02.11.2023 00:10, Stefano Stabellini wrote:
> > On Wed, 1 Nov 2023, Nicola Vetrini wrote:
> > > As stated in rules.rst, functions used only in asm modules
> > > are allowed to have no prior declaration visible when being
> > > defined, hence these functions are marked with an
> > > 'asmlinkage' macro, which is then deviated for MISRA C:2012
> > > Rule 8.4.
> > >
> > > Signed-off-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
> > > ---
> > > Changes in v3:
> > > - added SAF deviations for vmx counterparts to svm functions.
> > > Changes in v5:
> > > - drop SAF deviations in favour of the pseudo-attribute asmlinkage
> > > Changes in v6:
> > > - conditioned asmlinkage definition to make it overridable;
> > > - move the pseudo-attribute after the return type
> > > ---
> > >  automation/eclair_analysis/ECLAIR/deviations.ecl | 9 +++++++++
> > >  docs/misra/deviations.rst                        | 6 ++++++
> > >  xen/arch/x86/hvm/svm/intr.c                      | 2 +-
> > >  xen/arch/x86/hvm/svm/nestedsvm.c                 | 2 +-
> > >  xen/arch/x86/hvm/svm/svm.c                       | 4 ++--
> > >  xen/arch/x86/hvm/vmx/intr.c                      | 2 +-
> > >  xen/arch/x86/hvm/vmx/vmx.c                       | 4 ++--
> > >  xen/arch/x86/hvm/vmx/vvmx.c                      | 2 +-
> > >  xen/arch/x86/traps.c                             | 2 +-
> > >  xen/arch/x86/x86_64/traps.c                      | 2 +-
> > >  xen/include/xen/compiler.h                       | 5 +++++
> > >  11 files changed, 30 insertions(+), 10 deletions(-)
> > >
> > > diff --git a/automation/eclair_analysis/ECLAIR/deviations.ecl 
> > > b/automation/eclair_analysis/ECLAIR/deviations.ecl
> > > index fa56e5c00a27..06619ecf7e8d 100644
> > > --- a/automation/eclair_analysis/ECLAIR/deviations.ecl
> > > +++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
> > > @@ -163,6 +163,15 @@ Therefore the absence of prior declarations is 
> > > safe."
> > >  -config=MC3R1.R8.4,reports+={safe, 
> > > "first_area(any_loc(file(gcov)))"}
> > >  -doc_end
> > >
> > > +-doc_begin="Recognize the occurrence of current_stack_pointer as a 
> > > declaration."
> > > +-file_tag+={asm_defns, "^xen/arch/x86/include/asm/asm_defns\\.h$"}
> > > +-config=MC3R1.R8.4,declarations+={safe, 
> > > "loc(file(asm_defns))&&^current_stack_pointer$"}
> > > +-doc_end
> > > +
> > > +-doc_begin="asmlinkage is a marker to indicate that the function is 
> > > only used to interface with asm modules."
> > > +-config=MC3R1.R8.4,declarations+={safe,"loc(text(^(?s).*asmlinkage.*$, 
> > > -1..0))"}
> > > +-doc_end
> > > +
> > >  -doc_begin="The following variables are compiled in multiple 
> > > translation units
> > >  belonging to different executables and therefore are safe."
> > >  -config=MC3R1.R8.6,declarations+={safe, 
> > > "name(current_stack_pointer||bsearch||sort)"}
> > > diff --git a/docs/misra/deviations.rst b/docs/misra/deviations.rst
> > > index 8511a189253b..d468da2f5ce9 100644
> > > --- a/docs/misra/deviations.rst
> > > +++ b/docs/misra/deviations.rst
> > > @@ -133,6 +133,12 @@ Deviations related to MISRA C:2012 Rules:
> > >         configuration. Therefore, the absence of prior declarations 
> > > is safe.
> > >       - Tagged as `safe` for ECLAIR.
> > >
> > > +   * - R8.4
> > > +     - Functions and variables used only by asm modules are either 
> > > marked with
> > > +       the `asmlinkage` macro or with a SAF-1-safe textual deviation
> > > +       (see safe.json).
> > > +     - Tagged as `safe` for ECLAIR.
> > Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
> with ...
>
> > If Julien prefers a different wording I could modify on commit as 
> > needed
> ... wording clarified along the lines of his subsequent reply. Yet 
> better
> would be, as also suggested by him, to accompany this with a 2nd patch
> replacing the now deprecated SAF-* comments.
>
> Jan
Yes, as replied to Julien in this thread: a second patch will be 
submitted shortly.
--
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)