[XEN PATCH][for-4.19 v4] xen: Add deviations for MISRA C:2012 Rule 7.1

[Nicola Vetrini <nicola.vetrini@bugseng.com>]

As specified in rules.rst, these constants can be used
in the code.

Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
---
Changes in v2:
- replace some SAF deviations with configurations
Changes in v3:
- refine configurations and justifications
Changes in v4:
- updated deviation record comment.
---
 automation/eclair_analysis/ECLAIR/deviations.ecl | 10 ++++++----
 docs/misra/deviations.rst                        |  7 +++++++
 docs/misra/safe.json                             |  8 ++++++++
 xen/arch/x86/hvm/svm/emulate.c                   |  6 +++---
 xen/common/inflate.c                             |  4 ++--
 5 files changed, 26 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..8aaaa1473fb4 100644
--- a/docs/misra/deviations.rst
+++ b/docs/misra/deviations.rst
@@ -90,6 +90,13 @@ 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. Such places
+       are marked safe with a /\* octal-ok \*/ in-code comment, or with a SAF
+       comment (see safe.json).
+     - Tagged as `safe` for ECLAIR.
+
    * - R7.2
      - Violations caused by __HYPERVISOR_VIRT_START are related to the
        particular use of it done in xen_mk_ulong.
diff --git a/docs/misra/safe.json b/docs/misra/safe.json
index 39c5c056c7d4..7ea47344ffcc 100644
--- a/docs/misra/safe.json
+++ b/docs/misra/safe.json
@@ -20,6 +20,14 @@
         },
         {
             "id": "SAF-2-safe",
+            "analyser": {
+                "eclair": "MC3R1.R7.1"
+            },
+            "name": "Rule 7.1: constants defined in specifications, manuals, and algorithm descriptions",
+            "text": "It is safe to use certain octal constants the way they are defined in specifications, manuals, and algorithm descriptions."
+        },
+        {
+            "id": "SAF-3-safe",
             "analyser": {},
             "name": "Sentinel",
             "text": "Next ID to be used"
diff --git a/xen/arch/x86/hvm/svm/emulate.c b/xen/arch/x86/hvm/svm/emulate.c
index aa2c61c433b3..93ac1d3435f9 100644
--- a/xen/arch/x86/hvm/svm/emulate.c
+++ b/xen/arch/x86/hvm/svm/emulate.c
@@ -90,9 +90,9 @@ unsigned int svm_get_insn_len(struct vcpu *v, unsigned int instr_enc)
         if ( !instr_modrm )
             return emul_len;
 
-        if ( modrm_mod       == MASK_EXTR(instr_modrm, 0300) &&
-             (modrm_reg & 7) == MASK_EXTR(instr_modrm, 0070) &&
-             (modrm_rm  & 7) == MASK_EXTR(instr_modrm, 0007) )
+        if ( modrm_mod       == MASK_EXTR(instr_modrm, 0300) && /* octal-ok */
+             (modrm_reg & 7) == MASK_EXTR(instr_modrm, 0070) && /* octal-ok */
+             (modrm_rm  & 7) == MASK_EXTR(instr_modrm, 0007) )  /* octal-ok */
             return emul_len;
     }
 
diff --git a/xen/common/inflate.c b/xen/common/inflate.c
index 8fa4b96d12a3..be6a9115187e 100644
--- a/xen/common/inflate.c
+++ b/xen/common/inflate.c
@@ -1201,8 +1201,8 @@ static int __init gunzip(void)
     magic[1] = NEXTBYTE();
     method   = NEXTBYTE();
 
-    if (magic[0] != 037 ||
-        ((magic[1] != 0213) && (magic[1] != 0236))) {
+    /* SAF-2-safe */
+    if (magic[0] != 037 || ((magic[1] != 0213) && (magic[1] != 0236))) {
         error("bad gzip magic numbers");
         return -1;
     }
-- 
2.34.1