Re: [XEN PATCH v3 5/7] automation/eclair: add deviations for Rule 20.7

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Fri, 29 Mar 2024, Nicola Vetrini wrote:
> These deviations deal with the following cases:
> - macro arguments used directly as initializer list arguments;
> - uses of the __config_enabled macro, that can't be brought
>   into compliance without breaking its functionality;
> - exclude files that are out of scope (efi headers and cpu_idle);
> - uses of alternative_{call,vcall}[0-9] macros.
> 
> The existing configuration for R20.7 is reordered so that it matches the
> cases listed in its documentation comment.
> 
> Signed-off-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>

> ---
>  .../eclair_analysis/ECLAIR/deviations.ecl     | 25 +++++++++++++++++--
>  docs/misra/deviations.rst                     | 14 ++++++++++-
>  docs/misra/rules.rst                          |  2 +-
>  3 files changed, 37 insertions(+), 4 deletions(-)
> 
> diff --git a/automation/eclair_analysis/ECLAIR/deviations.ecl 
> b/automation/eclair_analysis/ECLAIR/deviations.ecl
> index de9ba723fbc7..70756503f594 100644
> --- a/automation/eclair_analysis/ECLAIR/deviations.ecl
> +++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
> @@ -401,12 +401,33 @@ unexpected result when the structure is given as 
> argument to a sizeof() operator
>  
>  -doc_begin="Code violating Rule 20.7 is safe when macro parameters are used: 
> (1)
>  as function arguments; (2) as macro arguments; (3) as array indices; (4) as 
> lhs
> -in assignments."
> +in assignments; (5) as initializers, possibly designated, in initalizer 
> lists."
>  -config=MC3R1.R20.7,expansion_context=
>  {safe, "context(__call_expr_arg_contexts)"},
> +{safe, "left_right(^[(,\\[]$,^[),\\]]$)"},
>  {safe, "context(skip_to(__expr_non_syntactic_contexts, 
> stmt_child(node(array_subscript_expr), subscript)))"},
>  {safe, "context(skip_to(__expr_non_syntactic_contexts, 
> stmt_child(operator(assign), lhs)))"},
> -{safe, "left_right(^[(,\\[]$,^[),\\]]$)"}
> +{safe, "context(skip_to(__expr_non_syntactic_contexts, 
> stmt_child(node(init_list_expr||designated_init_expr), init)))"}
> +-doc_end
> +
> +-doc_begin="Violations involving the __config_enabled macros cannot be fixed 
> without
> +breaking the macro's logic; futhermore, the macro is only ever used in the 
> context
> +of the IS_ENABLED or STATIC_IF/STATIC_IF_NOT macros, so it always receives a 
> literal
> +0 or 1 as input, posing no risk to safety."
> +-config=MC3R1.R20.7,reports+={safe, 
> "any_area(any_loc(any_exp(macro(^___config_enabled$))))"}
> +-doc_end
> +
> +-doc_begin="Violations due to the use of macros defined in files that are
> +not in scope for compliance are allowed, as that is imported code."
> +-file_tag+={gnu_efi_include, "^xen/include/efi/.*$"}
> +-file_tag+={acpi_cpu_idle, "^xen/arch/x86/acpi/cpu_idle\\.c$"}
> +-config=MC3R1.R20.7,reports+={safe, 
> "any_area(any_loc(file(gnu_efi_include)))"}
> +-config=MC3R1.R20.7,reports+={safe, "any_area(any_loc(file(acpi_cpu_idle)))"}
> +-doc_end
> +
> +-doc_begin="To avoid compromising readability, the macros 
> alternative_(v)?call[0-9] are allowed
> +not to parenthesize their arguments."
> +-config=MC3R1.R20.7,reports+={safe, 
> "any_area(any_loc(any_exp(macro(^alternative_(v)?call[0-9]$))))"}
>  -doc_end
>  
>  -doc_begin="Uses of variadic macros that have one of their arguments defined 
> as
> diff --git a/docs/misra/deviations.rst b/docs/misra/deviations.rst
> index eb5ef2bd9dd6..5fdacfd420a1 100644
> --- a/docs/misra/deviations.rst
> +++ b/docs/misra/deviations.rst
> @@ -345,7 +345,19 @@ Deviations related to MISRA C:2012 Rules:
>         (1) as function arguments;
>         (2) as macro arguments;
>         (3) as array indices;
> -       (4) as lhs in assignments.
> +       (4) as lhs in assignments;
> +       (5) as initializers, possibly designated, in initalizer lists.
> +     - Tagged as `safe` for ECLAIR.
> +
> +   * - R20.7
> +     - Violations due to the use of macros defined in files that are not
> +       in scope for compliance are allowed, as that is imported code.
> +     - Tagged as `safe` for ECLAIR.
> +
> +   * - R20.7
> +     - To avoid compromising readability, the macros 
> `alternative_(v)?call[0-9]`
> +       are allowed not to parenthesize their arguments, as there are already
> +       sanity checks in place.
>       - Tagged as `safe` for ECLAIR.
>  
>     * - R20.12
> diff --git a/docs/misra/rules.rst b/docs/misra/rules.rst
> index 1e134ccebc48..3914af08495b 100644
> --- a/docs/misra/rules.rst
> +++ b/docs/misra/rules.rst
> @@ -560,7 +560,7 @@ maintainers if you want to suggest a change.
>         shall be enclosed in parentheses
>       - Extra parentheses are not required when macro parameters are used
>         as function arguments, as macro arguments, array indices, lhs in
> -       assignments
> +       assignments or as initializers in initalizer lists.
>  
>     * - `Rule 20.9 
> <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_20_09.c>`_
>       - Required
> -- 
> 2.34.1
>