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

[Jan Beulich <jbeulich@xxxxxxxx>]

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.

Jan