[ros-diffs] [aandrejevic] 60995: [FAST486] - Fix the privilege checks. - Store the CPL in a special field, so that it doesn't get mixed up with the lowest 2 bits of real mode selectors while switching into pro...

Author: aandrejevic
Date: Fri Nov 15 02:32:08 2013
New Revision: 60995

URL: http://svn.reactos.org/svn/reactos?rev=60995&view=rev
Log:
[FAST486]
- Fix the privilege checks.
- Store the CPL in a special field, so that it doesn't get mixed up
  with the lowest 2 bits of real mode selectors while switching
  into protected mode.
- Reset the exception count after a successful ISR call.
- In Fast486OpcodeGroup0F01, check for prefix overrides after parsing
  the Mod-Reg-R/M, which might add a SS: prefix override in some cases.


Modified:
    branches/ntvdm/include/reactos/libs/fast486/fast486.h
    branches/ntvdm/lib/fast486/common.c
    branches/ntvdm/lib/fast486/common.inl
    branches/ntvdm/lib/fast486/fast486.c
    branches/ntvdm/lib/fast486/opgroups.c

Modified: branches/ntvdm/include/reactos/libs/fast486/fast486.h
URL:
http://svn.reactos.org/svn/reactos/branches/ntvdm/include/reactos/libs/fast…
==============================================================================
--- branches/ntvdm/include/reactos/libs/fast486/fast486.h	[iso-8859-1] (original)
+++ branches/ntvdm/include/reactos/libs/fast486/fast486.h	[iso-8859-1] Fri Nov 15 02:32:08
2013
@@ -394,6 +394,7 @@
     FAST486_REG InstPtr, SavedInstPtr;
     FAST486_FLAGS_REG Flags;
     FAST486_TABLE_REG Gdtr, Idtr, Ldtr, Tss;
+    UCHAR Cpl;
     ULONG ControlRegisters[FAST486_NUM_CTRL_REGS];
     ULONG DebugRegisters[FAST486_NUM_DBG_REGS];
     ULONG ExceptionCount;

Modified: branches/ntvdm/lib/fast486/common.c
URL:
http://svn.reactos.org/svn/reactos/branches/ntvdm/lib/fast486/common.c?rev=…
==============================================================================
--- branches/ntvdm/lib/fast486/common.c	[iso-8859-1] (original)
+++ branches/ntvdm/lib/fast486/common.c	[iso-8859-1] Fri Nov 15 02:32:08 2013
@@ -65,7 +65,8 @@
             return FALSE;
         }
 
-        if (GET_SEGMENT_RPL(CachedDescriptor->Selector) >
CachedDescriptor->Dpl)
+        if ((!InstFetch && (GET_SEGMENT_RPL(CachedDescriptor->Selector) >
CachedDescriptor->Dpl))
+            || (Fast486GetCurrentPrivLevel(State) > CachedDescriptor->Dpl))
         {
             Fast486Exception(State, FAST486_EXCEPTION_GP);
             return FALSE;
@@ -132,7 +133,8 @@
             return FALSE;
         }
 
-        if (GET_SEGMENT_RPL(CachedDescriptor->Selector) >
CachedDescriptor->Dpl)
+        if ((GET_SEGMENT_RPL(CachedDescriptor->Selector) >
CachedDescriptor->Dpl)
+            || (Fast486GetCurrentPrivLevel(State) > CachedDescriptor->Dpl))
         {
             Fast486Exception(State, FAST486_EXCEPTION_GP);
             return FALSE;
@@ -330,8 +332,18 @@
         && (State->ControlRegisters[FAST486_REG_CR0] & FAST486_CR0_PE))
     {
         /* Push the error code */
-        Fast486StackPush(State, ErrorCode);
-    }
+        if (!Fast486StackPush(State, ErrorCode))
+        {
+            /*
+             * If this function failed, that means Fast486Exception
+             * was called again, so just return in this case.
+             */
+            return;
+        }
+    }
+
+    /* Reset the exception count */
+    State->ExceptionCount = 0;
 }
 
 /* EOF */

Modified: branches/ntvdm/lib/fast486/common.inl
URL:
http://svn.reactos.org/svn/reactos/branches/ntvdm/lib/fast486/common.inl?re…
==============================================================================
--- branches/ntvdm/lib/fast486/common.inl	[iso-8859-1] (original)
+++ branches/ntvdm/lib/fast486/common.inl	[iso-8859-1] Fri Nov 15 02:32:08 2013
@@ -27,16 +27,8 @@
 INT
 Fast486GetCurrentPrivLevel(PFAST486_STATE State)
 {
-    if (State->ControlRegisters[FAST486_REG_CR0] & FAST486_CR0_PE)
-    {
-        /* In protected mode, return the RPL of the CS */
-        return GET_SEGMENT_RPL(State->SegmentRegs[FAST486_REG_CS].Selector);
-    }
-    else
-    {
-        /* Real mode is always in supervisor mode */
-        return 0;
-    }
+    /* Return the CPL, or 3 if we're in virtual 8086 mode */
+    return (!State->Flags.Vm) ? State->Cpl : 3;
 }
 
 FORCEINLINE
@@ -464,7 +456,10 @@
         else if (Segment == FAST486_REG_CS)
         {
             /* Loading the code segment */
-            // TODO: NOT IMPLEMENTED
+            // TODO: Implement security checks, call gates, etc...
+
+            /* Update CPL */
+            State->Cpl = GET_SEGMENT_RPL(Selector);
         }
         else
         {
@@ -478,7 +473,7 @@
             }
 
             if ((GET_SEGMENT_RPL(Selector) > GdtEntry.Dpl)
-                && (Fast486GetCurrentPrivLevel(State) > GdtEntry.Dpl))
+                || (Fast486GetCurrentPrivLevel(State) > GdtEntry.Dpl))
             {
                 Fast486Exception(State, FAST486_EXCEPTION_GP);
                 return FALSE;

Modified: branches/ntvdm/lib/fast486/fast486.c
URL:
http://svn.reactos.org/svn/reactos/branches/ntvdm/lib/fast486/fast486.c?rev…
==============================================================================
--- branches/ntvdm/lib/fast486/fast486.c	[iso-8859-1] (original)
+++ branches/ntvdm/lib/fast486/fast486.c	[iso-8859-1] Fri Nov 15 02:32:08 2013
@@ -238,6 +238,9 @@
     /* Initialize the registers */
     State->Flags.AlwaysSet = 1;
     State->InstPtr.LowWord = 0xFFF0;
+
+    /* Set the CPL to 0 */
+    State->Cpl = 0;
 
     /* Initialize segments */
     for (i = 0; i < FAST486_NUM_SEG_REGS; i++)

Modified: branches/ntvdm/lib/fast486/opgroups.c
URL:
http://svn.reactos.org/svn/reactos/branches/ntvdm/lib/fast486/opgroups.c?re…
==============================================================================
--- branches/ntvdm/lib/fast486/opgroups.c	[iso-8859-1] (original)
+++ branches/ntvdm/lib/fast486/opgroups.c	[iso-8859-1] Fri Nov 15 02:32:08 2013
@@ -1668,17 +1668,17 @@
     NO_LOCK_PREFIX();
     TOGGLE_ADSIZE(AddressSize);
 
+    if (!Fast486ParseModRegRm(State, AddressSize, &ModRegRm))
+    {
+        /* Exception occurred */
+        return FALSE;
+    }
+
     /* Check for the segment override */
     if (State->PrefixFlags & FAST486_PREFIX_SEG)
     {
         /* Use the override segment instead */
         Segment = State->SegmentOverride;
-    }
-
-    if (!Fast486ParseModRegRm(State, AddressSize, &ModRegRm))
-    {
-        /* Exception occurred */
-        return FALSE;
     }
 
     /* Check which operation this is */