[PATCH v4] misra: add deviations of MISRA C Rule 5.5

[Dmytro Prokopchuk1 <dmytro_prokopchuk1@xxxxxxxx>]

MISRA C Rule 5.5 states: "Identifiers shall be distinct from macro names".

Update ECLAIR configuration to deviate clashes: specify the macros that
should be ignored. Update deviations.rst and rules.rst accordingly.

Signed-off-by: Dmytro Prokopchuk <dmytro_prokopchuk1@xxxxxxxx>
---
Changes in v4:
- fixed formatting (aligned length chars per line)
- set 'ignored_macros' as a regex expression
- set a deviation restriction on xen/common/grant_table.c
- s/ensures/to ensure/
- fixed grammar errors

Link to v3:
https://patchew.org/Xen/e681e0c083d945f48e6d0add1aee32af16be224e.1753911247.git.dmytro._5Fprokopchuk1@xxxxxxxx/

Test CI pipeline:
https://gitlab.com/xen-project/people/dimaprkp4k/xen/-/pipelines/1960066579
---
 .../eclair_analysis/ECLAIR/deviations.ecl     | 10 +++++++++
 docs/misra/deviations.rst                     | 22 +++++++++++++++++++
 docs/misra/rules.rst                          | 17 ++++++++++++++
 3 files changed, 49 insertions(+)

diff --git a/automation/eclair_analysis/ECLAIR/deviations.ecl 
b/automation/eclair_analysis/ECLAIR/deviations.ecl
index 483507e7b9..ab3400fc89 100644
--- a/automation/eclair_analysis/ECLAIR/deviations.ecl
+++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
@@ -117,6 +117,16 @@ it defines would (in the common case) be already defined. 
Peer reviewed by the c
 -config=MC3A2.R5.5,reports+={deliberate, 
"any_area(decl(kind(function))||any_loc(macro(name(memcpy||memset||memmove))))&&any_area(any_loc(file(^xen/common/libelf/libelf-private\\.h$)))"}
 -doc_end
 
+-doc_begin="Clashes between bitops functions and macro names are deliberate.
+These macros are needed for input validation and error handling."
+-config=MC3A2.R5.5,ignored_macros+="^(__)?(test|set|clear|change|test_and_(set|clear|change))_bit$"
+-doc_end
+
+-doc_begin="Clashes between grant table functions and macro names in 
'xen/common/grant_table.c' are deliberate.
+These macros address differences in argument count during compile-time, 
effectively discarding unused parameters to avoid warnings or errors related to 
them."
+-config=MC3A2.R5.5,ignored_macros+="name(update_gnttab_par||parse_gnttab_limit)&&loc(file(^xen/common/grant_table\\.c$))"
+-doc_end
+
 -doc_begin="The type \"ret_t\" is deliberately defined multiple times,
 depending on the guest."
 -config=MC3A2.R5.6,reports+={deliberate,"any_area(any_loc(text(^.*ret_t.*$)))"}
diff --git a/docs/misra/deviations.rst b/docs/misra/deviations.rst
index e78179fcb8..4c64a8be62 100644
--- a/docs/misra/deviations.rst
+++ b/docs/misra/deviations.rst
@@ -142,6 +142,28 @@ Deviations related to MISRA C:2012 Rules:
        memmove.
      - Tagged as `deliberate` for ECLAIR.
 
+   * - R5.5
+     - Clashes between bitops ('__test_and_set_bit', '__test_and_clear_bit',
+       '__test_and_change_bit', 'test_bit', 'set_bit', 'clear_bit', 
'change_bit',
+       'test_and_set_bit', 'test_and_clear_bit', 'test_and_change_bit')
+       functions and macro names are intentional. These are necessary for error
+       handling and input validation to ensure that the size of the object 
being
+       referenced by the memory address (passed as an argument to the macro)
+       meets the minimum requirements for the bit operation. This prevents 
unsafe
+       operations on improperly sized data types that could lead to undefined
+       behavior or memory corruption. The macros encapsulate this conditional
+       logic into a single, reusable form, simplifying the code and avoiding
+       function call overhead. Also this bit operations API was inherited from
+       Linux and should be kept for familiarity.
+     - ECLAIR has been configured to ignore these macros.
+
+   * - R5.5
+     - Clashes between grant table ('update_gnttab_par', 'parse_gnttab_limit')
+       functions and macro names are intentional. These macros address
+       differences in argument count during compile-time, effectively 
discarding
+       unused 2nd and 3rd parameters to avoid warnings or errors related to 
them.
+     - ECLAIR has been configured to ignore these macros.
+
    * - R5.6
      - The type ret_t is deliberately defined multiple times depending on the
        type of guest to service.
diff --git a/docs/misra/rules.rst b/docs/misra/rules.rst
index 3e014a6298..cba15933fe 100644
--- a/docs/misra/rules.rst
+++ b/docs/misra/rules.rst
@@ -196,6 +196,23 @@ maintainers if you want to suggest a change.
            #define f(x, y) f(x, y)
            void f(int x, int y);
 
+       Clashes between bitops functions and macro names are allowed
+       because they are used for input validation and error handling.
+       Example::
+
+           static inline void set_bit(int nr, volatile void *addr)
+           {
+               asm volatile ( "lock btsl %1,%0"
+                              : "+m" (ADDR) : "Ir" (nr) : "memory");
+           }
+           #define set_bit(nr, addr) ({                            \
+               if ( bitop_bad_size(addr) ) __bitop_bad_size();     \
+               set_bit(nr, addr);                                  \
+           })
+
+       Clashes between grant table functions and macro names are allowed
+       because they are used for discarding unused parameters.
+
    * - `Rule 5.6 
<https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_05_06.c>`_
      - Required
      - A typedef name shall be a unique identifier
-- 
2.43.0