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Re: [XEN PATCH v2] arm64/vfp: address MISRA C:2012 Dir 4.3



On 24/08/2023 10:01, Michal Orzel wrote:
Hi Nicola,

On 24/08/2023 09:37, Nicola Vetrini wrote:


Directive 4.3 prescribes the following:
"Assembly language shall be encapsulated and isolated",
on the grounds of improved readability and ease of maintenance.

A static inline function is the chosen encapsulation mechanism.

No functional change.

Signed-off-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
---
Changes in v2:
- Switched to a static inline function
---
xen/arch/arm/arm64/vfp.c | 78 ++++++++++++++++++++++------------------
 1 file changed, 44 insertions(+), 34 deletions(-)

diff --git a/xen/arch/arm/arm64/vfp.c b/xen/arch/arm/arm64/vfp.c
index 2d0d7c2e6ddb..5c884380ee42 100644
--- a/xen/arch/arm/arm64/vfp.c
+++ b/xen/arch/arm/arm64/vfp.c
@@ -4,6 +4,48 @@
 #include <asm/vfp.h>
 #include <asm/arm64/sve.h>

+static inline void save_state(uint64_t *fpregs)
+{
+    asm volatile("stp q0, q1, [%1, #16 * 0]\n\t"
+                 "stp q2, q3, [%1, #16 * 2]\n\t"
+                 "stp q4, q5, [%1, #16 * 4]\n\t"
+                 "stp q6, q7, [%1, #16 * 6]\n\t"
+                 "stp q8, q9, [%1, #16 * 8]\n\t"
+                 "stp q10, q11, [%1, #16 * 10]\n\t"
+                 "stp q12, q13, [%1, #16 * 12]\n\t"
+                 "stp q14, q15, [%1, #16 * 14]\n\t"
+                 "stp q16, q17, [%1, #16 * 16]\n\t"
+                 "stp q18, q19, [%1, #16 * 18]\n\t"
+                 "stp q20, q21, [%1, #16 * 20]\n\t"
+                 "stp q22, q23, [%1, #16 * 22]\n\t"
+                 "stp q24, q25, [%1, #16 * 24]\n\t"
+                 "stp q26, q27, [%1, #16 * 26]\n\t"
+                 "stp q28, q29, [%1, #16 * 28]\n\t"
+                 "stp q30, q31, [%1, #16 * 30]\n\t"
+                 : "=Q" (*fpregs) : "r" (fpregs));
+}
+
+static inline void restore_state(uint64_t *fpregs)
This can be const as you are loading data from fpregs into registers


I wonder whether this would make a difference, given that the return type is void.
It's fine either way, tough.

--
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)



 


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