[RFC PATCH 2/4] xen/arm64: bitops: justify uninitialized variable inside a macro

[Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>]

The macro 'testop' expands to a function that declares the local
variable 'oldbit', which is written before being set, but is such a
way that is not amenable to automatic checking.

Therefore, a deviation comment, is introduced to document this situation.

A similar reasoning applies to macro 'guest_testop'.

Signed-off-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
---
 docs/misra/safe.json                     | 16 ++++++++++++++++
 xen/arch/arm/arm64/lib/bitops.c          |  3 +++
 xen/arch/arm/include/asm/guest_atomics.h |  3 +++
 3 files changed, 22 insertions(+)

diff --git a/docs/misra/safe.json b/docs/misra/safe.json
index 244001f5be..4cf7cbf57b 100644
--- a/docs/misra/safe.json
+++ b/docs/misra/safe.json
@@ -20,6 +20,22 @@
         },
         {
             "id": "SAF-2-safe",
+            "analyser": {
+                "eclair": "MC3R1.R9.1"
+            },
+            "name": "Rule 9.1: initializer not needed",
+            "text": "The following local variables are possibly subject to 
being read before being written, but code inspection ensured that the control 
flow in the construct where they appear ensures that no such event may happen."
+        },
+        {
+            "id": "SAF-3-safe",
+            "analyser": {
+                "eclair": "MC3R1.R9.1"
+            },
+            "name": "Rule 9.1: initializer not needed",
+            "text": "The following local variables are possibly subject to 
being read before being written, but code inspection ensured that the control 
flow in the construct where they appear ensures that no such event may happen."
+        },
+        {
+            "id": "SAF-4-safe",
             "analyser": {},
             "name": "Sentinel",
             "text": "Next ID to be used"
diff --git a/xen/arch/arm/arm64/lib/bitops.c b/xen/arch/arm/arm64/lib/bitops.c
index 20e3f3d6ce..e0728bb29d 100644
--- a/xen/arch/arm/arm64/lib/bitops.c
+++ b/xen/arch/arm/arm64/lib/bitops.c
@@ -114,8 +114,11 @@ bitop(change_bit, eor)
 bitop(clear_bit, bic)
 bitop(set_bit, orr)
 
+/* SAF-2-safe MC3R1.R9.1 */
 testop(test_and_change_bit, eor)
+/* SAF-2-safe MC3R1.R9.1 */
 testop(test_and_clear_bit, bic)
+/* SAF-2-safe MC3R1.R9.1 */
 testop(test_and_set_bit, orr)
 
 static always_inline bool int_clear_mask16(uint16_t mask, volatile uint16_t *p,
diff --git a/xen/arch/arm/include/asm/guest_atomics.h 
b/xen/arch/arm/include/asm/guest_atomics.h
index a1745f8613..9d8f8ec3a3 100644
--- a/xen/arch/arm/include/asm/guest_atomics.h
+++ b/xen/arch/arm/include/asm/guest_atomics.h
@@ -67,8 +67,11 @@ guest_bitop(change_bit)
 /* test_bit does not use load-store atomic operations */
 #define guest_test_bit(d, nr, p) ((void)(d), test_bit(nr, p))
 
+/* SAF-3-safe MC3R1.R9.1 */
 guest_testop(test_and_set_bit)
+/* SAF-3-safe MC3R1.R9.1 */
 guest_testop(test_and_clear_bit)
+/* SAF-3-safe MC3R1.R9.1 */
 guest_testop(test_and_change_bit)
 
 #undef guest_testop
-- 
2.34.1