Re: [XEN PATCH] automation/eclair_analysis: address violations of Rule 18.2

[Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>]

On 2024-09-06 08:03, Jan Beulich wrote:
> On 05.09.2024 18:37, Nicola Vetrini wrote:
> > MISRA C Rule 18.2 states: "Subtraction between pointers shall
> > only be applied to pointers that address elements of the same array".
> >
> > Subtractions between pointer where at least one symbol is a
> > symbol defined by the linker are safe and thus deviated, because
> > the compiler cannot exploit the undefined behaviour that would
> > arise from violating the rules in this case.
> >
> > To create an ECLAIR configuration that contains the list of
> > linker-defined symbols, the script "linker-symbols.sh" is used
> > after a build of xen (without static analysis) is performed.
> > The generated file "linker_symbols.ecl" is then used as part of the
> > static analysis configuration.
> >
> > Additional changes to the ECLAIR integration are:
> > - perform a build of xen without static analysis during prepare.sh
> > - run the scripts to generated ECL configuration during the 
> > prepare.sh,
> >   rather than analysis.sh
> > - export ECLAIR_PROJECT_ROOT earlier, to allow such generation
> >
> > Additionally, the macro page_to_mfn performs a subtraction that is 
> > safe,
> > so its uses are deviated.
> >
> > No functional changes.
> >
> > Signed-off-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
> > ---
> > Macro page_to_pdx is also the cause of some caution reports:
> > perhaps that should be deviated as well, since its definition is very
> > similar to page_to_mfn.
> >
> > Relevant CI runs:
> >
> > - arm64: 
> > https://saas.eclairit.com:3787/fs/var/local/eclair/xen-project.ecdf/xen-project/people/bugseng/xen/ECLAIR_normal/MC3R1.R18.2/ARM64/7754928624/PROJECT.ecd;/by_service/MC3R1.R18.2.html
> > - x86_64: 
> > https://saas.eclairit.com:3787/fs/var/local/eclair/xen-project.ecdf/xen-project/people/bugseng/xen/ECLAIR_normal/MC3R1.R18.2/X86_64/7754928613/PROJECT.ecd;/by_service/MC3R1.R18.2.html
> > - x86_64 (without page_to_pdx reports): 
> > https://saas.eclairit.com:3787/fs/var/local/eclair/xen-project.ecdf/xen-project/people/bugseng/xen/ECLAIR_normal/MC3R1.R18.2/X86_64/7754928613/PROJECT.ecd;/by_service/MC3R1.R18.2.html#{"select":true,"selection":{"hiddenAreaKinds":[],"hiddenSubareaKinds":[],"show":false,"selector":{"enabled":true,"negated":false,"kind":0,"domain":"message","inputs":[{"enabled":true,"text":"^.*expanded 
> > from macro `page_to_pdx'"}]}}}
> > ---
> >  automation/eclair_analysis/ECLAIR/analyze.sh  |  6 ----
> >  .../eclair_analysis/ECLAIR/deviations.ecl     | 11 +++++++
> >  .../eclair_analysis/ECLAIR/generate_ecl.sh    |  3 ++
> >  .../ECLAIR/generate_linker_symbols.sh         | 31 
> > +++++++++++++++++++
> >  automation/eclair_analysis/prepare.sh         |  6 +++-
> >  automation/scripts/eclair                     |  3 ++
> >  docs/misra/deviations.rst                     | 10 ++++++
> >  7 files changed, 63 insertions(+), 7 deletions(-)
> >  create mode 100755 
> > automation/eclair_analysis/ECLAIR/generate_linker_symbols.sh
> Nit: Dashes instead of underscores in names of new files, please.
>
> Jan
Thanks. Perhaps is will be a good idea to make a follow-up patch to use 
dashes consistently.
--
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)