From 4bcb47a522b92aeb36187f337f31d5b1c9b30909 Mon Sep 17 00:00:00 2001
From: Thomas Faber <thomas.faber@reactos.org>
Date: Tue, 19 Jul 2016 12:51:49 +0000
Subject: [PATCH] [NTOS:KE] - Load LDT on context switch if required.
 CORE-11511 #resolve

svn path=/trunk/; revision=71967
---
 reactos/ntoskrnl/ke/i386/context.c | 14 +++++++++++---
 reactos/ntoskrnl/ke/i386/ldt.c     |  2 +-
 reactos/ntoskrnl/ke/i386/thrdini.c | 13 +++++++++++--
 3 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/reactos/ntoskrnl/ke/i386/context.c b/reactos/ntoskrnl/ke/i386/context.c
index e1a7f11a6c5..5617a678514 100644
--- a/reactos/ntoskrnl/ke/i386/context.c
+++ b/reactos/ntoskrnl/ke/i386/context.c
@@ -34,9 +34,17 @@ KiSwapProcess(IN PKPROCESS NewProcess,
     /* Check for new LDT */
     if (NewProcess->LdtDescriptor.LimitLow != OldProcess->LdtDescriptor.LimitLow)
     {
-        /* Not handled yet */
-        UNIMPLEMENTED_DBGBREAK();
-        return;
+        if (NewProcess->LdtDescriptor.LimitLow)
+        {
+            KeSetGdtSelector(KGDT_LDT,
+                             ((PULONG)&NewProcess->LdtDescriptor)[0],
+                             ((PULONG)&NewProcess->LdtDescriptor)[1]);
+            Ke386SetLocalDescriptorTable(KGDT_LDT);
+        }
+        else
+        {
+            Ke386SetLocalDescriptorTable(0);
+        }
     }
 
     /* Update CR3 */
diff --git a/reactos/ntoskrnl/ke/i386/ldt.c b/reactos/ntoskrnl/ke/i386/ldt.c
index 14298de2994..3501712ffaf 100644
--- a/reactos/ntoskrnl/ke/i386/ldt.c
+++ b/reactos/ntoskrnl/ke/i386/ldt.c
@@ -167,7 +167,7 @@ BOOLEAN PspIsDescriptorValid(PLDT_ENTRY ldt_entry)
   if ((Base + SegLimit > (ULONG_PTR) MmHighestUserAddress) ||
       (Base > Base+SegLimit))
   {
-    DPRINT1("WARNING: Windows would mark this descriptor invalid!");
+    DPRINT1("WARNING: Windows would mark this descriptor invalid!\n");
   }
 
   /*
diff --git a/reactos/ntoskrnl/ke/i386/thrdini.c b/reactos/ntoskrnl/ke/i386/thrdini.c
index ba7935c3dd1..66264b5030e 100644
--- a/reactos/ntoskrnl/ke/i386/thrdini.c
+++ b/reactos/ntoskrnl/ke/i386/thrdini.c
@@ -345,8 +345,17 @@ KiSwapContextExit(IN PKTHREAD OldThread,
         /* Check if there is a different LDT */
         if (*(PULONGLONG)&OldProcess->LdtDescriptor != *(PULONGLONG)&NewProcess->LdtDescriptor)
         {
-            DPRINT1("LDT switch not implemented\n");
-            ASSERT(FALSE);
+            if (NewProcess->LdtDescriptor.LimitLow)
+            {
+                KeSetGdtSelector(KGDT_LDT,
+                                 ((PULONG)&NewProcess->LdtDescriptor)[0],
+                                 ((PULONG)&NewProcess->LdtDescriptor)[1]);
+                Ke386SetLocalDescriptorTable(KGDT_LDT);
+            }
+            else
+            {
+                Ke386SetLocalDescriptorTable(0);
+            }
         }
 
         /* Switch address space and flush TLB */
-- 
2.17.1