docs/misra: new rules addition

For Dir 1.1, a document describing all implementation-defined behaviour
(i.e. gcc-specific behavior) will be added to docs/misra, also including
implementation-specific (gcc-specific) appropriate types for bit-field
relevant to Rule 6.1.

Rule 21.21 is lacking an example on gitlab but the rule is
straightforward: we don't use stdlib at all in Xen.

Signed-off-by: Stefano Stabellini <stefano.stabellini@amd.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>

docs/misra/rules.rst

@@ -40,6 +40,12 @@ existing codebase are work-in-progress.
      - Summary
      - Notes
 
+   * - `Dir 1.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_01_01.c>`_
+     - Required
+     - Any implementation-defined behaviour on which the output of the
+       program depends shall be documented and understood
+     -
+
    * - `Dir 2.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_02_01.c>`_
      - Required
      - All source files shall compile without any compilation errors
@@ -57,6 +63,13 @@ existing codebase are work-in-progress.
        header file being included more than once
      -
 
+   * - `Dir 4.11 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_04_11.c>`_
+     - Required
+     - The validity of values passed to library functions shall be checked
+     - We do not have libraries in Xen (libfdt and others are not
+       considered libraries from MISRA C point of view as they are
+       imported in source form)
+
    * - `Dir 4.14 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_04_14.c>`_
      - Required
      - The validity of values received from external sources shall be
@@ -133,6 +146,12 @@ existing codebase are work-in-progress.
        headers (xen/include/public/) are allowed to retain longer
        identifiers for backward compatibility.
 
+   * - `Rule 6.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_06_01.c>`_
+     - Required
+     - Bit-fields shall only be declared with an appropriate type
+     - In addition to the C99 types, we also consider appropriate types
+       enum and all explicitly signed / unsigned integer types.
+
    * - `Rule 6.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_06_02.c>`_
      - Required
      - Single-bit named bit fields shall not be of a signed type
@@ -143,6 +162,32 @@ existing codebase are work-in-progress.
      - Octal constants shall not be used
      -
 
+   * - `Rule 7.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_07_02.c>`_
+     - Required
+     - A "u" or "U" suffix shall be applied to all integer constants
+       that are represented in an unsigned type
+     - The rule asks that any integer literal that is implicitly
+       unsigned is made explicitly unsigned by using one of the
+       indicated suffixes.  As an example, on a machine where the int
+       type is 32-bit wide, 0x77777777 is signed whereas 0x80000000 is
+       (implicitly) unsigned. In order to comply with the rule, the
+       latter should be rewritten as either 0x80000000u or 0x80000000U.
+       Consistency considerations may suggest using the same suffix even
+       when not required by the rule. For instance, if one has:
+
+       Original: f(0x77777777); f(0x80000000);
+
+       one should do
+
+       Solution 1: f(0x77777777U); f(0x80000000U);
+
+       over
+
+       Solution 2: f(0x77777777); f(0x80000000U);
+
+       after having ascertained that "Solution 1" is compatible with the
+       intended semantics.
+
    * - `Rule 7.3 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_07_03.c>`_
      - Required
      - The lowercase character l shall not be used in a literal suffix
@@ -314,6 +359,11 @@ existing codebase are work-in-progress.
        used following a subsequent call to the same function
      -
 
+   * - `Rule 21.21 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/>`_
+     - Required
+     - The Standard Library function system of <stdlib.h> shall not be used
+     -
+
    * - `Rule 22.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_22_02.c>`_
      - Mandatory
      - A block of memory shall only be freed if it was allocated by means of a