From b163fa4521c4ee1c37de53fb1ad30bc48890ff33 Mon Sep 17 00:00:00 2001
From: Stefan Lankes <stlankes@users.noreply.github.com>
Date: Sun, 20 Aug 2017 10:19:25 +0200
Subject: [PATCH 1/3] reload the segment descriptors after loading GDT

---
 arch/x86/kernel/entry.asm | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/x86/kernel/entry.asm b/arch/x86/kernel/entry.asm
index fadc21c3d..28d49943b 100644
--- a/arch/x86/kernel/entry.asm
+++ b/arch/x86/kernel/entry.asm
@@ -264,6 +264,16 @@ extern gp
 ; C as 'extern void gdt_flush();'
 gdt_flush:
     lgdt [gp]
+    ; reload the segment descriptors
+    mov eax, 0x10
+    mov ds, eax
+    mov es, eax
+    mov ss, eax
+    xor eax, eax
+    mov fs, eax
+    mov gs, eax
+    jmp 0x08:flush2
+flush2:
     ret
 
 ; The first 32 interrupt service routines (ISR) entries correspond to exceptions.

From e38722c7f4d7dddf8a86826fb14e7b77a99fbdf2 Mon Sep 17 00:00:00 2001
From: Stefan Lankes <stlankes@users.noreply.github.com>
Date: Sun, 20 Aug 2017 10:36:49 +0200
Subject: [PATCH 2/3] remove 32bit code

---
 arch/x86/kernel/entry.asm | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/entry.asm b/arch/x86/kernel/entry.asm
index 28d49943b..022f0209c 100644
--- a/arch/x86/kernel/entry.asm
+++ b/arch/x86/kernel/entry.asm
@@ -272,7 +272,10 @@ gdt_flush:
     xor eax, eax
     mov fs, eax
     mov gs, eax
-    jmp 0x08:flush2
+    ; create pseudo interrupt to set cs
+    push 0x08
+    push flush2
+    iretq
 flush2:
     ret
 

From 3b8e6791ee47d6210870515de58b95ca87e700d5 Mon Sep 17 00:00:00 2001
From: Stefan Lankes <slankes@eonerc.rwth-aachen.de>
Date: Sun, 20 Aug 2017 10:51:52 +0200
Subject: [PATCH 3/3] create valid pseudo interrupt to set cs

---
 arch/x86/kernel/entry.asm | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/entry.asm b/arch/x86/kernel/entry.asm
index 022f0209c..5775dfbcc 100644
--- a/arch/x86/kernel/entry.asm
+++ b/arch/x86/kernel/entry.asm
@@ -273,11 +273,13 @@ gdt_flush:
     mov fs, eax
     mov gs, eax
     ; create pseudo interrupt to set cs
-    push 0x08
-    push flush2
+    push QWORD 0x10             ; SS
+    push rsp                    ; RSP
+    add QWORD [rsp], 0x08       ; => value of rsp before the creation of a pseudo interrupt
+    pushfq                      ; RFLAGS
+    push QWORD 0x08             ; CS
+    push QWORD rollback         ; RIP
     iretq
-flush2:
-    ret
 
 ; The first 32 interrupt service routines (ISR) entries correspond to exceptions.
 ; Some exceptions will push an error code onto the stack which is specific to