[dgorbachev] 40008: Return to an old idea of MiMapPageToZeroInHyperSpace(), "fix" bug #4267.

Author: dgorbachev
Date: Sat Mar 14 04:20:18 2009
New Revision: 40008

URL: http://svn.reactos.org/svn/reactos?rev=40008&view=rev
Log:
Return to an old idea of MiMapPageToZeroInHyperSpace(), "fix" bug #4267.

Modified:
    trunk/reactos/ntoskrnl/mm/hypermap.c

Modified: trunk/reactos/ntoskrnl/mm/hypermap.c
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/mm/hypermap.c?rev=...
==============================================================================
--- trunk/reactos/ntoskrnl/mm/hypermap.c [iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/mm/hypermap.c [iso-8859-1] Sat Mar 14 04:20:18 2009
@@ -14,8 +14,11 @@

/* GLOBALS ********************************************************************/

+#define MI_ZEROING_PTES  255
+
 PMMPTE MmFirstReservedMappingPte;
 PMMPTE MmLastReservedMappingPte;
+PMMPTE MmFirstReservedZeroingPte;
 MMPTE HyperTemplatePte;
 PEPROCESS HyperProcess;
 KIRQL HyperIrql;
@@ -40,6 +43,8 @@
     MmFirstReservedMappingPte = MiAddressToPte(MI_MAPPING_RANGE_START);
     MmLastReservedMappingPte =  MiAddressToPte(MI_MAPPING_RANGE_END);
     MmFirstReservedMappingPte->u.Hard.PageFrameNumber = MI_HYPERSPACE_PTES;
+    MmFirstReservedZeroingPte = MiAddressToPte(MI_ZERO_PTE);
+    MmFirstReservedZeroingPte->u.Hard.PageFrameNumber = MI_ZEROING_PTES;
 }

PVOID
@@ -134,38 +139,62 @@
 {
     MMPTE TempPte;
     PMMPTE PointerPte;
+    PFN_NUMBER Offset;
     PVOID Address; 
-    
+
     //
     // Never accept page 0
     //
     ASSERT(Page != 0);
-    
+
     //
     // Build the PTE
     //
     TempPte = HyperTemplatePte;
     TempPte.u.Hard.PageFrameNumber = Page;
-    
-    //
-    // Get the Zero PTE and its address
-    //
-    PointerPte = MiAddressToPte(MI_ZERO_PTE);
+
+    //
+    // Pick the first zeroing PTE
+    //
+    PointerPte = MmFirstReservedZeroingPte;
+
+    //
+    // Now get the first free PTE
+    //
+    Offset = PFN_FROM_PTE(PointerPte);
+    if (!Offset)
+    {
+        //
+        // Reset the PTEs
+        //
+        Offset = MI_ZEROING_PTES;
+        KeFlushProcessTb();
+    }
+
+    //
+    // Prepare the next PTE
+    //
+    PointerPte->u.Hard.PageFrameNumber = Offset - 1;
+
+    //
+    // Write the current PTE
+    //
+    PointerPte += Offset;
+    *PointerPte = TempPte;
+
+    //
+    // Return the address
+    //
     Address = (PVOID)((ULONG_PTR)PointerPte << 10);
-    
-    //
-    // Invalidate the old address
-    //
-    __invlpg(Address);
-    
-    //
-    // Write the current PTE
-    //
-    TempPte.u.Hard.PageFrameNumber = Page;
-    *PointerPte = TempPte;
-    
-    //
-    // Return the address
-    //
     return Address;
 }
+
+VOID
+NTAPI
+MiUnmapPageInZeroSpace(IN PVOID Address)
+{
+    //
+    // Blow away the mapping
+    //
+    MiAddressToPte(Address)->u.Long = 0;
+}