From d00577ac8da0ebf1bd181a769e343724f9ea9c4e Mon Sep 17 00:00:00 2001
From: Aiken Harris <harraiken91@gmail.com>
Date: Tue, 31 Mar 2026 23:10:45 +0200
Subject: [PATCH] Fix previous mode detection by reading CS from the trap frame

---
 xtoskrnl/ar/i686/archsup.S         | 2 +-
 xtoskrnl/includes/ar/i686/asmsup.h | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/xtoskrnl/ar/i686/archsup.S b/xtoskrnl/ar/i686/archsup.S
index 1dcbceb..dcd8817 100644
--- a/xtoskrnl/ar/i686/archsup.S
+++ b/xtoskrnl/ar/i686/archsup.S
@@ -111,7 +111,7 @@ _Ar\Type\Vector\()Start:
 
         /* Test previous mode and swap GS if needed */
         movl $0, TrapPreviousMode(%ebp)
-        mov %cs, %ax
+        mov TrapSegCs(%ebp), %ax
         and $3, %al
         mov %al, TrapPreviousMode(%ebp)
         jz KernelMode\Type\Vector
diff --git a/xtoskrnl/includes/ar/i686/asmsup.h b/xtoskrnl/includes/ar/i686/asmsup.h
index 1593bc8..6b228f2 100644
--- a/xtoskrnl/includes/ar/i686/asmsup.h
+++ b/xtoskrnl/includes/ar/i686/asmsup.h
@@ -25,6 +25,7 @@
 #define TrapSegFs                               40
 #define TrapSegGs                               42
 #define TrapVector                              72
+#define TrapSegCs                               84
 #define TrapEsp                                 92
 #define TrapSegSs                               96