[xen staging] xen/compiler: deviate the inline macro for MISRA C Rule 20.4

[patchbot@xxxxxxx]

commit d2686bf96483668b826b6a428679ba03402d4a52
Author:     Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
AuthorDate: Thu Mar 14 13:54:14 2024 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Mar 14 13:54:14 2024 +0100

    xen/compiler: deviate the inline macro for MISRA C Rule 20.4
    
    Rule 20.4 states: "A macro shall not be defined with the same name
    as a keyword".
    
    Defining this macro with the same name as the inline keyword
    allows for additionally checking that out-of-lined static inline
    functions end up in the correct section while minimizing churn and
    has a positive impact on the overall safety. See [1] for additional
    context on the motivation of this deviation.
    
    No functional change.
    
    [1] 
https://lore.kernel.org/xen-devel/adaa6d55-266d-4df8-8967-9340080d17e4@xxxxxxxxxx/
    
    Signed-off-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
---
 docs/misra/deviations.rst  | 6 ++++++
 docs/misra/safe.json       | 8 ++++++++
 xen/include/xen/compiler.h | 1 +
 3 files changed, 15 insertions(+)

diff --git a/docs/misra/deviations.rst b/docs/misra/deviations.rst
index 6d532a872d..41fa5b31b0 100644
--- a/docs/misra/deviations.rst
+++ b/docs/misra/deviations.rst
@@ -328,6 +328,12 @@ Deviations related to MISRA C:2012 Rules:
        improve readability.
      - Tagged as `deliberate` for ECLAIR.
 
+   * - R20.4
+     - The override of the keyword \"inline\" in xen/compiler.h is present so
+       that section contents checks pass when the compiler chooses not to
+       inline a particular function.
+     - Comment-based deviation.
+
    * - R20.7
      - Code violating Rule 20.7 is safe when macro parameters are used:
        (1) as function arguments;
diff --git a/docs/misra/safe.json b/docs/misra/safe.json
index 952324f85c..d361d0e65c 100644
--- a/docs/misra/safe.json
+++ b/docs/misra/safe.json
@@ -28,6 +28,14 @@
         },
         {
             "id": "SAF-3-safe",
+            "analyser": {
+                "eclair": "MC3R1.R20.4"
+            },
+            "name": "MC3R1.R20.4: allow the definition of a macro with the 
same name as a keyword in some special cases",
+            "text": "The definition of a macro with the same name as a keyword 
can be useful in certain configurations to improve the guarantees that can be 
provided by Xen. See docs/misra/deviations.rst for a precise rationale for all 
such cases."
+        },
+        {
+            "id": "SAF-4-safe",
             "analyser": {},
             "name": "Sentinel",
             "text": "Next ID to be used"
diff --git a/xen/include/xen/compiler.h b/xen/include/xen/compiler.h
index 16d554f2a5..fc87a2edad 100644
--- a/xen/include/xen/compiler.h
+++ b/xen/include/xen/compiler.h
@@ -82,6 +82,7 @@
  * inline functions not expanded inline get placed in .init.text.
  */
 #include <xen/init.h>
+/* SAF-3-safe MISRA C Rule 20.4: allow section checks to pass when not inlined 
*/
 #define inline inline __init
 #endif
 
--
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