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Implement kernel stack deallocation and physical page freeing logic
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This commit is contained in:
Aiken Harris
2026-01-05 01:20:21 +01:00
parent 0a43a93f41
commit cb6efc648f
3 changed files with 231 additions and 1 deletions
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5
xtoskrnl/includes/mm/pfn.hh
View File

@@ -39,6 +39,11 @@ namespace MM
STATIC XTAPI PFN_NUMBER AllocateBootstrapPages(IN PFN_NUMBER NumberOfPages);
STATIC XTAPI PFN_NUMBER AllocatePhysicalPage(IN ULONG Color);
STATIC XTAPI VOID ComputePfnDatabaseSize(VOID);
STATIC XTAPI VOID DecrementReferenceCount(IN PMMPFN Pfn1,
IN PFN_NUMBER PageFrameIndex);
STATIC XTAPI VOID DecrementShareCount(IN PMMPFN Pfn1,
IN PFN_NUMBER PageFrameIndex);
STATIC XTAPI VOID FreePhysicalPage(IN PMMPTE PointerPte);
STATIC XTAPI ULONG_PTR GetHighestPhysicalPage(VOID);
STATIC XTAPI ULONGLONG GetNumberOfPhysicalPages(VOID);
STATIC XTAPI PFN_NUMBER GetPfnDatabaseSize(VOID);

30
xtoskrnl/mm/kpool.cc
View File

@@ -155,7 +155,35 @@ VOID
MM::KernelPool::FreeKernelStack(IN PVOID Stack,
IN ULONG StackSize)
{
UNIMPLEMENTED;
PFN_COUNT StackPages;
PMMPTE PointerPte;
ULONG Index;
/* Get the PTE for the top of the stack, including the guard page */
MM::Paging::AdvancePte(MM::Paging::GetPteAddress(Stack), -1);
/* Convert the stack size into a page count */
StackPages = SIZE_TO_PAGES(StackSize);
/* Acquire the PFN database lock */
KE::QueuedSpinLockGuard SpinLock(SystemSpaceLock);
/* Loop through each page of the stack that needs to be freed */
for(Index = 0; Index < StackPages; Index++)
{
/* Ensure the PTE is valid */
if(MM::Paging::PteValid(PointerPte))
{
/* Free the physical page */
MM::Pfn::FreePhysicalPage(PointerPte);
}
/* Advance to the next PTE */
PointerPte = MM::Paging::AdvancePte(PointerPte, -1);
}
/* Release all system PTEs used by the stack, including the guard page */
MM::Pte::ReleaseSystemPtes(PointerPte, StackPages + 1, SystemPteSpace);
}
/**

197
xtoskrnl/mm/pfn.cc
View File

@@ -129,6 +129,203 @@ MM::Pfn::DecrementAvailablePages(VOID)
AvailablePages--;
}
/**
* Decrements the reference count of a PFN entry.
*
* @param PageFrameNumber
* A pointer to the PFN database entry for the physical page.
*
* @param PageFrameIndex
* The page frame number of the physical page.
*
* @return This routine does not return any value.
*
* @since XT 1.0
*/
XTAPI
VOID
MM::Pfn::DecrementReferenceCount(IN PMMPFN PageFrameNumber,
IN PFN_NUMBER PageFrameIndex)
{
/* Decrement the PFN reference count */
PageFrameNumber->u3.e2.ReferenceCount--;
/* If other references exist, no further action is needed */
if(PageFrameNumber->u3.e2.ReferenceCount)
{
/* No further action can be taken */
return;
}
/* If the reference count is zero, the share count should also be zero */
if(PageFrameNumber->u2.ShareCount)
{
/* This indicates a bug; crash the system */
KE::Crash::PanicEx(0x4E,
0x07,
PageFrameIndex,
PageFrameNumber->u2.ShareCount,
0);
}
/* Check if the PTE is marked as being ready for removal */
if(MM::Paging::GetPte(PageFrameNumber->PteAddress) & 0x1)
{
/* Check the page's cache attribute */
if((PageFrameNumber->u3.e1.CacheAttribute != PfnCached) &&
(PageFrameNumber->u3.e1.CacheAttribute != PfnNotMapped))
{
UNIMPLEMENTED;
}
/* The page is no longer needed, free it by linking it to the free list */
LinkFreePage(PageFrameIndex);
/* No further action is needed */
return;
}
/* The page is unreferenced and unmapped, so place it on the appropriate list */
if(PageFrameNumber->u3.e1.Modified == 1)
{
/* Link dirty page to the modified list */
LinkPage(&ModifiedPagesList, PageFrameIndex);
}
else
{
/* Check if the page has been marked for removal */
if(PageFrameNumber->u3.e1.RemovalRequested == 1)
{
/* Update the page location and move it to the bad pages list */
PageFrameNumber->u3.e1.PageLocation = StandbyPageList;
LinkPage(&BadPagesList, PageFrameIndex);
}
else
{
/* Link clean page to the standby list */
LinkPage(&StandbyPagesList, PageFrameIndex)
}
}
}
/**
* Decrements the share count of a PFN entry, which represents the number of PTEs mapping the page.
*
* @param PageFrameNumber
* A pointer to the PFN database entry for the physical page.
*
* @param PageFrameIndex
* The page frame number of the physical page.
*
* @return This routine does not return any value.
*
* @since XT 1.0
*/
XTAPI
VOID
MM::Pfn::DecrementShareCount(IN PMMPFN PageFrameNumber,
IN PFN_NUMBER PageFrameIndex)
{
/* Ensure the page is in a valid state */
if((PageFrameNumber->u3.e1.PageLocation != ActiveAndValid) &&
(PageFrameNumber->u3.e1.PageLocation != StandbyPageList))
{
/* This indicates a bug; crash the system */
KE::Crash::PanicEx(0x4E,
0x99,
PageFrameIndex,
PageFrameNumber->u3.e1.PageLocation,
0);
}
/* Decrement the PFN share count */
PageFrameNumber->u2.ShareCount--;
/* Check if the share count has dropped to zero */
if(!PageFrameNumber->u2.ShareCount)
{
/* Check if this is a prototype PTE */
if(PageFrameNumber->u3.e1.PrototypePte)
{
/* Transition the PTE to invalid state */
MM::Paging::TransitionPte(PageFrameNumber->PteAddress,
MM::Paging::GetPteSoftwareProtection(&PageFrameNumber->OriginalPte));
}
/* Mark the page as being in a transition state */
PageFrameNumber->u3.e1.PageLocation = TransitionPage;
/* Check if there are still outstanding references */
if(PageFrameNumber->u3.e2.ReferenceCount == 1)
{
/* Check if the PTE is marked as being ready for removal */
if(MM::Paging::GetPte(PageFrameNumber->PteAddress) & 0x1)
{
/* Reset the reference count */
PageFrameNumber->u3.e2.ReferenceCount = 0;
/* Check the page's cache attribute */
if((PageFrameNumber->u3.e1.CacheAttribute != PfnCached) &&
(PageFrameNumber->u3.e1.CacheAttribute != PfnNotMapped))
{
UNIMPLEMENTED;
}
/* Mark the page as active and valid again */
PageFrameNumber->u3.e1.PageLocation = ActiveAndValid;
/* The page is no longer needed, free it by linking it to the free list */
MM::Pfn::LinkFreePage(PageFrameIndex);
}
else
{
/* The PTE can not be removed yet, decrement the reference count */
DecrementReferenceCount(PageFrameNumber, PageFrameIndex);
}
}
else
{
/* There are still some outstanding references, decrement the reference count */
PageFrameNumber->u3.e2.ReferenceCount--;
}
}
}
/**
* Frees a physical page that is mapped by a given PTE.
*
* @param PointerPte
* A pointer to the Page Table Entry (PTE) that maps the physical page to be freed.
*
* @return This routine does not return a value.
*
* @since XT 1.0
*/
XTAPI
VOID
MM::Pfn::FreePhysicalPage(IN PMMPTE PointerPte)
{
PFN_COUNT PageFrameNumber, PageTableFrameNumber;
PMMPFN PageFrame, PageTableFrame;
/* Get the page frame number from the PTE */
PageFrameNumber = MM::Paging::GetPageFrameNumber(PointerPte);
PageFrame = MM::Pfn::GetPfnEntry(PageFrameNumber);
/* Get the page table frame number corresponding to the PTE */
PageTableFrameNumber = PageFrame->u4.PteFrame;
PageTableFrame = MM::Pfn::GetPfnEntry(PageTableFrameNumber);
/* Decrement the share count of the page table */
MM::Pfn::DecrementShareCount(PageTableFrame, PageTableFrameNumber);
/* Mark the PTE as being ready for removal */
MM::Paging::SetPte(PageFrame->PteAddress, MM::Paging::GetPte(PageFrame->PteAddress) | 1);
/* Decrement the share count of the page */
MM::Pfn::DecrementShareCount(PageFrame, PageFrameNumber);
}
/**
* Retrieves the highest physical page number (PFN) detected in the system.
*