[reactos] 01/01: [NTOS:MM] Use MI_ZERO_PTES as the number of usable zeroing PTEs, not the total allocated. CORE-11856

[Thomas Faber]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=754e175d12454cecc3996…

commit 754e175d12454cecc3996b207bf9650b048060e4
Author:     Thomas Faber <thomas.faber(a)reactos.org>
AuthorDate: Sat Nov 4 14:08:56 2017 +0100
Commit:     Thomas Faber <thomas.faber(a)reactos.org>
CommitDate: Sat Feb 22 12:33:54 2020 +0100

    [NTOS:MM] Use MI_ZERO_PTES as the number of usable zeroing PTEs, not the total
allocated. CORE-11856
    
    We'll now have 32 usable zeroing PTEs instead of 31.
    MP kernels will (some day) zero up to 32 pages at a time.
---
 ntoskrnl/mm/ARM3/hypermap.c  | 6 +++---
 ntoskrnl/mm/ARM3/i386/init.c | 6 +++---
 ntoskrnl/mm/amd64/init.c     | 7 ++++---
 3 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/ntoskrnl/mm/ARM3/hypermap.c b/ntoskrnl/mm/ARM3/hypermap.c
index 9391cee80bc..6f7c32aa45e 100644
--- a/ntoskrnl/mm/ARM3/hypermap.c
+++ b/ntoskrnl/mm/ARM3/hypermap.c
@@ -122,7 +122,7 @@ MiMapPagesInZeroSpace(IN PMMPFN Pfn1,
     //
     ASSERT(KeGetCurrentIrql() == PASSIVE_LEVEL);
     ASSERT(NumberOfPages != 0);
-    ASSERT(NumberOfPages <= (MI_ZERO_PTES - 1));
+    ASSERT(NumberOfPages <= MI_ZERO_PTES);
 
     //
     // Pick the first zeroing PTE
@@ -138,7 +138,7 @@ MiMapPagesInZeroSpace(IN PMMPFN Pfn1,
         //
         // Reset the PTEs
         //
-        Offset = MI_ZERO_PTES - 1;
+        Offset = MI_ZERO_PTES;
         PointerPte->u.Hard.PageFrameNumber = Offset;
         KeFlushProcessTb();
     }
@@ -192,7 +192,7 @@ MiUnmapPagesInZeroSpace(IN PVOID VirtualAddress,
     //
     ASSERT(KeGetCurrentIrql() == PASSIVE_LEVEL);
     ASSERT (NumberOfPages != 0);
-    ASSERT (NumberOfPages <= (MI_ZERO_PTES - 1));
+    ASSERT(NumberOfPages <= MI_ZERO_PTES);
 
     //
     // Get the first PTE for the mapped zero VA
diff --git a/ntoskrnl/mm/ARM3/i386/init.c b/ntoskrnl/mm/ARM3/i386/init.c
index 6d3e2e7045b..79ed102c230 100644
--- a/ntoskrnl/mm/ARM3/i386/init.c
+++ b/ntoskrnl/mm/ARM3/i386/init.c
@@ -522,14 +522,14 @@ MiInitMachineDependent(IN PLOADER_PARAMETER_BLOCK LoaderBlock)
     //
     // Reserve system PTEs for zeroing PTEs and clear them
     //
-    MiFirstReservedZeroingPte = MiReserveSystemPtes(MI_ZERO_PTES,
+    MiFirstReservedZeroingPte = MiReserveSystemPtes(MI_ZERO_PTES + 1,
                                                     SystemPteSpace);
-    RtlZeroMemory(MiFirstReservedZeroingPte, MI_ZERO_PTES * sizeof(MMPTE));
+    RtlZeroMemory(MiFirstReservedZeroingPte, (MI_ZERO_PTES + 1) * sizeof(MMPTE));
 
     //
     // Set the counter to maximum to boot with
     //
-    MiFirstReservedZeroingPte->u.Hard.PageFrameNumber = MI_ZERO_PTES - 1;
+    MiFirstReservedZeroingPte->u.Hard.PageFrameNumber = MI_ZERO_PTES;
 
     /* Lock PFN database */
     OldIrql = MiAcquirePfnLock();
diff --git a/ntoskrnl/mm/amd64/init.c b/ntoskrnl/mm/amd64/init.c
index 0f6ae0eceaa..6e3344bfe52 100644
--- a/ntoskrnl/mm/amd64/init.c
+++ b/ntoskrnl/mm/amd64/init.c
@@ -382,11 +382,12 @@ MiBuildSystemPteSpace(VOID)
     MiInitializeSystemPtes(PointerPte, MmNumberOfSystemPtes, SystemPteSpace);
 
     /* Reserve system PTEs for zeroing PTEs and clear them */
-    MiFirstReservedZeroingPte = MiReserveSystemPtes(MI_ZERO_PTES, SystemPteSpace);
-    RtlZeroMemory(MiFirstReservedZeroingPte, MI_ZERO_PTES * sizeof(MMPTE));
+    MiFirstReservedZeroingPte = MiReserveSystemPtes(MI_ZERO_PTES + 1,
+                                                    SystemPteSpace);
+    RtlZeroMemory(MiFirstReservedZeroingPte, (MI_ZERO_PTES + 1) * sizeof(MMPTE));
 
     /* Set the counter to maximum */
-    MiFirstReservedZeroingPte->u.Hard.PageFrameNumber = MI_ZERO_PTES - 1;
+    MiFirstReservedZeroingPte->u.Hard.PageFrameNumber = MI_ZERO_PTES;
 }
 
 static