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

[Nicola Vetrini]

On 26/10/2023 08:49, Jan Beulich wrote:

On 26.10.2023 00:34, Stefano Stabellini wrote:

On Wed, 25 Oct 2023, Jan Beulich wrote:

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.vetr...@bugseng.com>
---
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.

What about:

* - R7.1
  - It is safe to use certain octal constants the way they are defined

in specifications, manuals, and algorithm descriptions. Such places are marked safe with a /* octal-ok */ in-code comment, or with a SAF

    comment (see safe.json).

Fine with me.

Jan

Ok, I'll update the deviation record.

--
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)