page.c

ReactOS是一些高手根据Windows XP的内核编写出的类XP。内核实现机理和API函数调用几乎相同。甚至可以兼容XP的程序。喜欢研究系统内核的人可以看一看。

   {
      ULONG Pte;
      PULONG Pt;

      Pt = MmGetPageTableForProcess(Process, Address, FALSE);

      if (Pt == NULL)
      {
         if (WasDirty != NULL)
         {
            *WasDirty = FALSE;
         }
         if (Page != NULL)
         {
            *Page = 0;
         }
         return;
      }

      /*
       * Atomically set the entry to zero and get the old value.
       */
      Pte = InterlockedExchangeUL(Pt, 0);

      MiFlushTlb(Pt, Address);

      WasValid = (PAGE_MASK(Pte) != 0);
      if (WasValid)
      {
         Pfn = PTE_TO_PFN(Pte);
         MmMarkPageUnmapped(Pfn);
      }
      else
      {
         Pfn = 0;
      }

      if (FreePage && WasValid)
      {
         MmReleasePageMemoryConsumer(MC_NPPOOL, Pfn);
      }

      /*
       * Return some information to the caller
       */
      if (WasDirty != NULL)
      {
         *WasDirty = Pte & PA_DIRTY ? TRUE : FALSE;
      }
      if (Page != NULL)
      {
         *Page = Pfn;
      }
   }
   /*
    * Decrement the reference count for this page table.
    */
   if (Process != NULL && WasValid &&
       ((PMADDRESS_SPACE)&Process->VadRoot)->PageTableRefCountTable != NULL &&
       Address < MmSystemRangeStart)
   {
      PUSHORT Ptrc;
      ULONG Idx;

      Ptrc = ((PMADDRESS_SPACE)&Process->VadRoot)->PageTableRefCountTable;
      Idx = Ke386Pae ? PAE_ADDR_TO_PAGE_TABLE(Address) : ADDR_TO_PAGE_TABLE(Address);

      Ptrc[Idx]--;
      if (Ptrc[Idx] == 0)
      {
         MmFreePageTable(Process, Address);
      }
   }
}

VOID
NTAPI
MmDeletePageFileMapping(PEPROCESS Process, PVOID Address,
                        SWAPENTRY* SwapEntry)
/*
 * FUNCTION: Delete a virtual mapping
 */
{
   if (Ke386Pae)
   {
      ULONGLONG Pte;
      PULONGLONG Pt;

      Pt = MmGetPageTableForProcessForPAE(Process, Address, FALSE);
      if (Pt == NULL)
      {
         *SwapEntry = 0;
         return;
      }

      /*
       * Atomically set the entry to zero and get the old value.
       */
      Pte = 0LL;
      Pte = ExfpInterlockedExchange64UL(Pt, &Pte);

      MiFlushTlb((PULONG)Pt, Address);

      /*
       * Decrement the reference count for this page table.
       */
      if (Process != NULL && Pte &&
          ((PMADDRESS_SPACE)&Process->VadRoot)->PageTableRefCountTable != NULL &&
          Address < MmSystemRangeStart)
      {
         PUSHORT Ptrc;

         Ptrc = ((PMADDRESS_SPACE)&Process->VadRoot)->PageTableRefCountTable;

         Ptrc[PAE_ADDR_TO_PAGE_TABLE(Address)]--;
         if (Ptrc[PAE_ADDR_TO_PAGE_TABLE(Address)] == 0)
         {
            MmFreePageTable(Process, Address);
         }
      }


      /*
       * Return some information to the caller
       */
      *SwapEntry = Pte >> 1;
   }
   else
   {
      ULONG Pte;
      PULONG Pt;

      Pt = MmGetPageTableForProcess(Process, Address, FALSE);

      if (Pt == NULL)
      {
         *SwapEntry = 0;
         return;
      }

      /*
       * Atomically set the entry to zero and get the old value.
       */
      Pte = InterlockedExchangeUL(Pt, 0);

      MiFlushTlb(Pt, Address);

      /*
       * Decrement the reference count for this page table.
       */
      if (Process != NULL && Pte &&
          ((PMADDRESS_SPACE)&Process->VadRoot)->PageTableRefCountTable != NULL &&
          Address < MmSystemRangeStart)
      {
         PUSHORT Ptrc;

         Ptrc = ((PMADDRESS_SPACE)&Process->VadRoot)->PageTableRefCountTable;

         Ptrc[ADDR_TO_PAGE_TABLE(Address)]--;
         if (Ptrc[ADDR_TO_PAGE_TABLE(Address)] == 0)
         {
            MmFreePageTable(Process, Address);
         }
      }


      /*
       * Return some information to the caller
       */
      *SwapEntry = Pte >> 1;
   }
}

BOOLEAN
Mmi386MakeKernelPageTableGlobal(PVOID PAddress)
{
   if (Ke386Pae)
   {
      PULONGLONG Pt;
      PULONGLONG Pde;
      Pde = PAE_ADDR_TO_PDE(PAddress);
      if (*Pde == 0LL)
      {
         Pt = MmGetPageTableForProcessForPAE(NULL, PAddress, FALSE);
#if 0
         /* Non existing mappings are not cached within the tlb. We must not invalidate this entry */
         FLASH_TLB_ONE(PAddress);
#endif
         if (Pt != NULL)
         {
            return TRUE;
         }
      }
   }
   else
   {
      PULONG Pt, Pde;
      Pde = ADDR_TO_PDE(PAddress);
      if (*Pde == 0)
      {
         Pt = MmGetPageTableForProcess(NULL, PAddress, FALSE);
#if 0
         /* Non existing mappings are not cached within the tlb. We must not invalidate this entry */
         FLASH_TLB_ONE(PAddress);
#endif
         if (Pt != NULL)
         {
            return TRUE;
         }
      }
   }
   return(FALSE);
}

BOOLEAN
NTAPI
MmIsDirtyPage(PEPROCESS Process, PVOID Address)
{
   if (Ke386Pae)
   {
      return MmGetPageEntryForProcessForPAE(Process, Address) & PA_DIRTY ? TRUE : FALSE;
   }
   else
   {
      return MmGetPageEntryForProcess(Process, Address) & PA_DIRTY ? TRUE : FALSE;
   }
}

BOOLEAN
NTAPI
MmIsAccessedAndResetAccessPage(PEPROCESS Process, PVOID Address)
{
   if (Address < MmSystemRangeStart && Process == NULL)
   {
      DPRINT1("MmIsAccessedAndResetAccessPage is called for user space without a process.\n");
      KEBUGCHECK(0);
   }
   if (Ke386Pae)
   {
      PULONGLONG Pt;
      ULONGLONG Pte;
      ULONGLONG tmpPte;

      Pt = MmGetPageTableForProcessForPAE(Process, Address, FALSE);
      if (Pt == NULL)
      {
         KEBUGCHECK(0);
      }

      do
      {
         Pte = *Pt;
	 tmpPte = Pte & ~PA_ACCESSED;
      } while (Pte != ExfInterlockedCompareExchange64UL(Pt, &tmpPte, &Pte));

      if (Pte & PA_ACCESSED)
      {
         MiFlushTlb((PULONG)Pt, Address);
         return TRUE;
      }
      else
      {
         MmUnmapPageTable((PULONG)Pt);
         return FALSE;
      }
   }
   else
   {
      PULONG Pt;
      ULONG Pte;

      Pt = MmGetPageTableForProcess(Process, Address, FALSE);
      if (Pt == NULL)
      {
         KEBUGCHECK(0);
      }

      do
      {
         Pte = *Pt;
      } while (Pte != InterlockedCompareExchangeUL(Pt, Pte & ~PA_ACCESSED, Pte));

      if (Pte & PA_ACCESSED)
      {
         MiFlushTlb(Pt, Address);
         return TRUE;
      }
      else
      {
         MmUnmapPageTable(Pt);
         return FALSE;
      }
   }
}

VOID
NTAPI
MmSetCleanPage(PEPROCESS Process, PVOID Address)
{
   if (Address < MmSystemRangeStart && Process == NULL)
   {
      DPRINT1("MmSetCleanPage is called for user space without a process.\n");
      KEBUGCHECK(0);
   }
   if (Ke386Pae)
   {
      PULONGLONG Pt;
      ULONGLONG Pte;
      ULONGLONG tmpPte;

      Pt = MmGetPageTableForProcessForPAE(Process, Address, FALSE);

      if (Pt == NULL)
      {
         KEBUGCHECK(0);
      }

      do
      {
         Pte = *Pt;
	 tmpPte = Pte & ~PA_DIRTY;
      } while (Pte != ExfInterlockedCompareExchange64UL(Pt, &tmpPte, &Pte));

      if (Pte & PA_DIRTY)
      {
         MiFlushTlb((PULONG)Pt, Address);
      }
      else
      {
         MmUnmapPageTable((PULONG)Pt);
      }
   }
   else
   {
      PULONG Pt;
      ULONG Pte;

      Pt = MmGetPageTableForProcess(Process, Address, FALSE);

      if (Pt == NULL)
      {
         KEBUGCHECK(0);
      }

      do
      {
         Pte = *Pt;
      } while (Pte != InterlockedCompareExchangeUL(Pt, Pte & ~PA_DIRTY, Pte));

      if (Pte & PA_DIRTY)
      {
         MiFlushTlb(Pt, Address);
      }
      else
      {
         MmUnmapPageTable(Pt);
      }
   }
}

VOID
NTAPI
MmSetDirtyPage(PEPROCESS Process, PVOID Address)
{
   if (Address < MmSystemRangeStart && Process == NULL)
   {
      DPRINT1("MmSetDirtyPage is called for user space without a process.\n");
      KEBUGCHECK(0);
   }
   if (Ke386Pae)
   {
      PULONGLONG Pt;
      ULONGLONG Pte;
      ULONGLONG tmpPte;

      Pt = MmGetPageTableForProcessForPAE(Process, Address, FALSE);
      if (Pt == NULL)
      {
         KEBUGCHECK(0);
      }

      do
      {
         Pte = *Pt;
	 tmpPte = Pte | PA_DIRTY;
      } while (Pte != ExfInterlockedCompareExchange64UL(Pt, &tmpPte, &Pte));
      if (!(Pte & PA_DIRTY))
      {
         MiFlushTlb((PULONG)Pt, Address);
      }
      else
      {
         MmUnmapPageTable((PULONG)Pt);
      }
   }
   else
   {
      PULONG Pt;
      ULONG Pte;

      Pt = MmGetPageTableForProcess(Process, Address, FALSE);
      if (Pt == NULL)
      {
         KEBUGCHECK(0);
      }

      do
      {
         Pte = *Pt;
      } while (Pte != InterlockedCompareExchangeUL(Pt, Pte | PA_DIRTY, Pte));
      if (!(Pte & PA_DIRTY))
      {
         MiFlushTlb(Pt, Address);
      }
      else
      {
         MmUnmapPageTable(Pt);
      }
   }
}

VOID
NTAPI
MmEnableVirtualMapping(PEPROCESS Process, PVOID Address)
{
   if (Ke386Pae)
   {
      PULONGLONG Pt;
      ULONGLONG Pte;
      ULONGLONG tmpPte;

      Pt = MmGetPageTableForProcessForPAE(Process, Address, FALSE);
      if (Pt == NULL)
      {
         KEBUGCHECK(0);
      }

      do
      {
         Pte = *Pt;
	 tmpPte = Pte | PA_PRESENT;
      } while (Pte != ExfInterlockedCompareExchange64UL(Pt, &tmpPte, &Pte));
      if (!(Pte & PA_PRESENT))
      {
         MiFlushTlb((PULONG)Pt, Address);
      }
      else
      {
         MmUnmapPageTable((PULONG)Pt);
      }
   }
   else
   {
      PULONG Pt;
      ULONG Pte;

      Pt = MmGetPageTableForProcess(Process, Address, FALSE);
      if (Pt == NULL)
      {
         KEBUGCHECK(0);
      }

      do
      {
         Pte = *Pt;
      } while (Pte != InterlockedCompareExchangeUL(Pt, Pte | PA_PRESENT, Pte));
      if (!(Pte & PA_PRESENT))
      {
         MiFlushTlb(Pt, Address);
      }
      else
      {
         MmUnmapPageTable(Pt);
      }
   }
}

BOOLEAN
NTAPI
MmIsPagePresent(PEPROCESS Process, PVOID Address)
{
   if (Ke386Pae)
   {
      return MmGetPageEntryForProcessForPAE(Process, Address) & PA_PRESENT ? TRUE : FALSE;
   }
   else
   {
      return MmGetPageEntryForProcess(Process, Address) & PA_PRESENT ? TRUE : FALSE;
   }
}