From 441ccab2b4b37ed35be71e4cbde48c6c25f8449c Mon Sep 17 00:00:00 2001
From: Aleksandar Andrejevic <aandrejevic@reactos.org>
Date: Sat, 26 Sep 2015 19:22:50 +0000
Subject: [PATCH] [FAST486] Whether a TSS is 16-bit or 32-bit depends solely on
 its signature. Its size is irrelevant.

svn path=/trunk/; revision=69367
---
 reactos/lib/fast486/common.c   | 24 ++++++++++++------------
 reactos/lib/fast486/opgroups.c |  2 ++
 2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/reactos/lib/fast486/common.c b/reactos/lib/fast486/common.c
index 2c2a4ac2111..cb47a7eb3da 100644
--- a/reactos/lib/fast486/common.c
+++ b/reactos/lib/fast486/common.c
@@ -328,7 +328,7 @@ Fast486InterruptInternal(PFAST486_STATE State,
             if (!Fast486ReadLinearMemory(State,
                                          State->TaskReg.Base,
                                          &Tss,
-                                         State->TaskReg.Limit >= (sizeof(FAST486_TSS) - 1)
+                                         State->TaskReg.Modern
                                          ? sizeof(FAST486_TSS) : sizeof(FAST486_LEGACY_TSS),
                                          FALSE))
             {
@@ -347,7 +347,7 @@ Fast486InterruptInternal(PFAST486_STATE State,
             {
                 case 0:
                 {
-                    if (State->TaskReg.Limit >= (sizeof(FAST486_TSS) - 1))
+                    if (State->TaskReg.Modern)
                     {
                         NewSs = Tss.Ss0;
                         NewEsp = Tss.Esp0;
@@ -363,7 +363,7 @@ Fast486InterruptInternal(PFAST486_STATE State,
 
                 case 1:
                 {
-                    if (State->TaskReg.Limit >= (sizeof(FAST486_TSS) - 1))
+                    if (State->TaskReg.Modern)
                     {
                         NewSs = Tss.Ss1;
                         NewEsp = Tss.Esp1;
@@ -379,7 +379,7 @@ Fast486InterruptInternal(PFAST486_STATE State,
 
                 case 2:
                 {
-                    if (State->TaskReg.Limit >= (sizeof(FAST486_TSS) - 1))
+                    if (State->TaskReg.Modern)
                     {
                         NewSs = Tss.Ss2;
                         NewEsp = Tss.Esp2;
@@ -632,7 +632,7 @@ Fast486TaskSwitch(PFAST486_STATE State, FAST486_TASK_SWITCH_TYPE Type, USHORT Se
     if (!Fast486ReadLinearMemory(State,
                                  State->TaskReg.Base,
                                  &OldTss,
-                                 State->TaskReg.Limit >= (sizeof(FAST486_TSS) - 1)
+                                 State->TaskReg.Modern
                                  ? sizeof(FAST486_TSS) : sizeof(FAST486_LEGACY_TSS),
                                  FALSE))
     {
@@ -644,7 +644,7 @@ Fast486TaskSwitch(PFAST486_STATE State, FAST486_TASK_SWITCH_TYPE Type, USHORT Se
     /* If this is a task return, use the linked previous selector */
     if (Type == FAST486_TASK_RETURN)
     {
-        if (State->TaskReg.Limit >= (sizeof(FAST486_TSS) - 1)) Selector = LOWORD(OldTss.Link);
+        if (State->TaskReg.Modern) Selector = LOWORD(OldTss.Link);
         else Selector = OldLegacyTss->Link;
     }
 
@@ -761,7 +761,7 @@ Fast486TaskSwitch(PFAST486_STATE State, FAST486_TASK_SWITCH_TYPE Type, USHORT Se
     }
 
     /* Save the current task into the TSS */
-    if (State->TaskReg.Limit >= (sizeof(FAST486_TSS) - 1))
+    if (State->TaskReg.Modern)
     {
         OldTss.Cr3 = State->ControlRegisters[FAST486_REG_CR3];
         OldTss.Eip = State->InstPtr.Long;
@@ -805,7 +805,7 @@ Fast486TaskSwitch(PFAST486_STATE State, FAST486_TASK_SWITCH_TYPE Type, USHORT Se
     if (!Fast486WriteLinearMemory(State,
                                   State->TaskReg.Base,
                                   &OldTss,
-                                  State->TaskReg.Limit >= (sizeof(FAST486_TSS) - 1)
+                                  State->TaskReg.Modern
                                   ? sizeof(FAST486_TSS) : sizeof(FAST486_LEGACY_TSS),
                                   FALSE))
     {
@@ -1059,7 +1059,7 @@ Fast486CallGate(PFAST486_STATE State,
             if (!Fast486ReadLinearMemory(State,
                                          State->TaskReg.Base,
                                          &Tss,
-                                         State->TaskReg.Limit >= (sizeof(FAST486_TSS) - 1)
+                                         State->TaskReg.Modern
                                          ? sizeof(FAST486_TSS) : sizeof(FAST486_LEGACY_TSS),
                                          FALSE))
             {
@@ -1075,7 +1075,7 @@ Fast486CallGate(PFAST486_STATE State,
             {
                 case 0:
                 {
-                    if (State->TaskReg.Limit >= (sizeof(FAST486_TSS) - 1))
+                    if (State->TaskReg.Modern)
                     {
                         NewSs = Tss.Ss0;
                         NewEsp = Tss.Esp0;
@@ -1091,7 +1091,7 @@ Fast486CallGate(PFAST486_STATE State,
 
                 case 1:
                 {
-                    if (State->TaskReg.Limit >= (sizeof(FAST486_TSS) - 1))
+                    if (State->TaskReg.Modern)
                     {
                         NewSs = Tss.Ss1;
                         NewEsp = Tss.Esp1;
@@ -1107,7 +1107,7 @@ Fast486CallGate(PFAST486_STATE State,
 
                 case 2:
                 {
-                    if (State->TaskReg.Limit >= (sizeof(FAST486_TSS) - 1))
+                    if (State->TaskReg.Modern)
                     {
                         NewSs = Tss.Ss2;
                         NewEsp = Tss.Esp2;
diff --git a/reactos/lib/fast486/opgroups.c b/reactos/lib/fast486/opgroups.c
index 28ac67aaf1e..e7605f1b234 100644
--- a/reactos/lib/fast486/opgroups.c
+++ b/reactos/lib/fast486/opgroups.c
@@ -1960,6 +1960,8 @@ FAST486_OPCODE_HANDLER(Fast486ExtOpcodeGroup0F00)
             State->TaskReg.Selector = Selector;
             State->TaskReg.Base = GdtEntry.Base | (GdtEntry.BaseMid << 16) | (GdtEntry.BaseHigh << 24);
             State->TaskReg.Limit = GdtEntry.Limit | (GdtEntry.LimitHigh << 16);
+            State->TaskReg.Modern = GdtEntry.Signature == FAST486_TSS_SIGNATURE
+                                    || GdtEntry.Signature == FAST486_BUSY_TSS_SIGNATURE;
 
             if (GdtEntry.Granularity)
             {