[reactos] 01/02: [NTOS:MM] Allow "creating" a PDE in legacy Mm for foreign process

[Jérôme Gardou]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=57e8684bc60e9cf54105e…

commit 57e8684bc60e9cf54105e0dcf6c3a13a621cde41
Author:     Jérôme Gardou <jerome.gardou(a)reactos.org>
AuthorDate: Fri Jan 22 09:31:34 2021 +0100
Commit:     Jérôme Gardou <jerome.gardou(a)reactos.org>
CommitDate: Fri Jan 22 09:32:36 2021 +0100

    [NTOS:MM] Allow "creating" a PDE in legacy Mm for foreign process
---
 ntoskrnl/mm/i386/page.c | 35 +++++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/ntoskrnl/mm/i386/page.c b/ntoskrnl/mm/i386/page.c
index 336e65a3c45..83c52423d5a 100644
--- a/ntoskrnl/mm/i386/page.c
+++ b/ntoskrnl/mm/i386/page.c
@@ -219,10 +219,6 @@ MmGetPageTableForProcess(PEPROCESS Process, PVOID Address, BOOLEAN
Create)
             PMMPDE PdeBase;
             ULONG PdeOffset = MiGetPdeOffset(Address);
 
-            /* Nobody but page fault should ask for creating the PDE,
-             * Which imples that Process is the current one */
-            ASSERT(Create == FALSE);
-
             PdeBase =
MmCreateHyperspaceMapping(PTE_TO_PFN(Process->Pcb.DirectoryTableBase[0]));
             if (PdeBase == NULL)
             {
@@ -231,13 +227,32 @@ MmGetPageTableForProcess(PEPROCESS Process, PVOID Address, BOOLEAN
Create)
             PointerPde = PdeBase + PdeOffset;
             if (PointerPde->u.Hard.Valid == 0)
             {
-                MmDeleteHyperspaceMapping(PdeBase);
-                return NULL;
-            }
-            else
-            {
-                Pfn = PointerPde->u.Hard.PageFrameNumber;
+                KAPC_STATE ApcState;
+                NTSTATUS Status;
+
+                if (!Create)
+                {
+                    MmDeleteHyperspaceMapping(PdeBase);
+                    return NULL;
+                }
+
+                KeStackAttachProcess(&Process->Pcb, &ApcState);
+
+                Status = MiDispatchFault(0x1,
+                                     MiAddressToPte(Address),
+                                     MiAddressToPde(Address),
+                                     NULL,
+                                     FALSE,
+                                     Process,
+                                     NULL,
+                                     NULL);
+
+                KeUnstackDetachProcess(&ApcState);
+                if (!NT_SUCCESS(Status))
+                    return NULL;
             }
+
+            Pfn = PointerPde->u.Hard.PageFrameNumber;
             MmDeleteHyperspaceMapping(PdeBase);
             Pt = MmCreateHyperspaceMapping(Pfn);
             if (Pt == NULL)