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

[Jan Beulich <jbeulich@xxxxxxxx>]

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