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[PATCH 4/6] x86/cpufreq: annotate Eclair false-positives for rule 18.2


  • To: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Wed, 9 Sep 2026 15:00:42 +0200
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  • Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Teddy Astie <teddy.astie@xxxxxxxxxx>, Roger Pau Monné <roger@xxxxxxxxxxxxxx>, Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
  • Delivery-date: Wed, 09 Sep 2026 13:00:46 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

"Subtraction between pointers shall only be applied to pointers that
address elements of the same array" is not violated here. Elsewhere, on
simple "e - s" Eclair manages to notice this; apparently "(end ?: e)" is
too complex ("end" being derived from "s" a few lines earlier).

Suggested-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
As per Nicola Eclair 16.0.0 has this fixed.

--- a/docs/misra/false-positive-eclair.json
+++ b/docs/misra/false-positive-eclair.json
@@ -3,6 +3,13 @@
     "content": [
         {
             "id": "SAF-0-false-positive-eclair",
+            "violation-id": "MC3A2.R18.2",
+            "tool-version": "3.14.0",
+            "name": "Rule 18.2: pointer subtraction",
+            "text": "Cmdline parsing start/end pointers point into the same 
array"
+        },
+        {
+            "id": "SAF-1-false-positive-eclair",
             "violation-id": "",
             "tool-version": "",
             "name": "Sentinel",
--- a/xen/arch/x86/acpi/cpufreq/amd-cppc.c
+++ b/xen/arch/x86/acpi/cpufreq/amd-cppc.c
@@ -67,6 +67,7 @@ int __init amd_cppc_cmdline_parse(const
         {
             printk(XENLOG_WARNING
                    "cpufreq/amd-cppc: option '%.*s' not recognized\n",
+                   /* SAF-0-false-positive-eclair s, e, and end point into the 
cmdline array */
                    (int)((end ?: e) - s), s);
 
             return -EINVAL;
--- a/xen/arch/x86/acpi/cpufreq/hwp.c
+++ b/xen/arch/x86/acpi/cpufreq/hwp.c
@@ -85,6 +85,7 @@ int __init hwp_cmdline_parse(const char
         if ( !hwp_handle_option(s, end) )
         {
             printk(XENLOG_WARNING "cpufreq/hwp: option '%.*s' not 
recognized\n",
+                   /* SAF-0-false-positive-eclair s, e, and end point into the 
cmdline array */
                    (int)((end ?: e) - s), s);
 
             return -EINVAL;




 


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