Deduplicate PFN descriptor processing logic across architectures

2026-02-06 09:08:59 +01:00
parent a46f30045a
commit 0ce2741e18
3 changed files with 119 additions and 227 deletions
--- a/xtoskrnl/mm/pfn.cc
+++ b/xtoskrnl/mm/pfn.cc
@@ -942,6 +942,125 @@ MM::Pfn::LinkStandbyPage(IN PFN_NUMBER PageFrameIndex)
    IncrementAvailablePages();
 }

+/**
+ * Processes a memory descriptor and initializes the corresponding PFN database entries
+ *
+ * @param BasePage
+ *        The starting physical page number of the memory run
+ *
+ * @param PageCount
+ *        The number of pages in the memory run
+ *
+ * @param MemoryType
+ *        The type of memory as reported by the bootloader (e.g., free, ROM, in-use)
+ *
+ * @return This routine does not return any value.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+VOID
+MM::Pfn::ProcessMemoryDescriptor(IN PFN_NUMBER BasePage,
+                                 IN PFN_NUMBER PageCount,
+                                 IN LOADER_MEMORY_TYPE MemoryType)
+{
+    PVOID VirtualRangeStart, VirtualRangeEnd;
+    PFN_NUMBER PageNumber;
+    PMMPDE PointerPde;
+    PMMPFN Pfn;
+
+    /* Check if the memory descriptor describes a free memory region */
+    if(MM::Manager::VerifyMemoryTypeFree(MemoryType))
+    {
+        /* Iterate over each page in this free memory run */
+        for(PageNumber = 0; PageNumber < PageCount; PageNumber++)
+        {
+            /* Get the PFN entry for the current page and ensure it is not referenced */
+            Pfn = GetPfnEntry(BasePage + PageNumber);
+            if(Pfn->u3.e2.ReferenceCount == 0)
+            {
+                /* Add the page to the free list to make it available for allocation */
+                LinkFreePage(BasePage + PageNumber);
+            }
+        }
+    }
+    else
+    {
+        /* Calculate the virtual address range for this physical memory region */
+        VirtualRangeStart = (PVOID)(KSEG0_BASE + (BasePage << MM_PAGE_SHIFT));
+        VirtualRangeEnd = (PVOID)(KSEG0_BASE + ((BasePage + PageCount) << MM_PAGE_SHIFT));
+
+        /* Handle all other (non-free) memory types */
+        switch(MemoryType)
+        {
+            case LoaderBad:
+                /* This memory is marked as bad and should not be used */
+                for(PageNumber = 0; PageNumber < PageCount; PageNumber++)
+                {
+                    /* Link the page to the bad pages list */
+                    LinkPage(&BadPagesList, BasePage + PageNumber);
+                }
+                break;
+            case LoaderXIPRom:
+                /* Get the page directory entry for the current page */
+                PointerPde = MM::Paging::GetPdeAddress(VirtualRangeStart);
+
+                /* Initialize the page directory entries covering this memory range */
+                InitializePageDirectory(PointerPde, MM::Paging::GetPdeAddress(VirtualRangeEnd));
+
+                /* This memory range contains Read-Only Memory (ROM) */
+                for(PageNumber = 0; PageNumber < PageCount; PageNumber++)
+                {
+                    /* Get the PFN entry for the current ROM page */
+                    Pfn = GetPfnEntry(BasePage + PageNumber);
+
+                    /* Ensure that the page is not already in-use */
+                    if(Pfn->u3.e2.ReferenceCount == 0)
+                    {
+                        /* Initialize the PFN entry to represent a ROM page */
+                        Pfn->PteAddress = MM::Paging::GetPteAddress(VirtualRangeStart);
+                        Pfn->u1.Flink = 0;
+                        Pfn->u2.ShareCount = 0;
+                        Pfn->u3.e1.CacheAttribute = PfnCached;
+                        Pfn->u3.e1.PageLocation = 0;
+                        Pfn->u3.e1.PrototypePte = 1;
+                        Pfn->u3.e1.Rom = 1;
+                        Pfn->u3.e2.ReferenceCount = 0;
+                        Pfn->u4.InPageError = 0;
+                        Pfn->u4.PteFrame = MM::Paging::GetPageFrameNumber(PointerPde);
+                    }
+                }
+                break;
+            default:
+                /* Get the page directory entry for the current page */
+                PointerPde = MM::Paging::GetPdeAddress(VirtualRangeStart);
+
+                /* Initialize the page directory entries covering this memory range */
+                InitializePageDirectory(PointerPde, MM::Paging::GetPdeAddress(VirtualRangeEnd));
+
+                /* All other types are considered in-use (ie, by the kernel, ACPI, etc) */
+                for(PageNumber = 0; PageNumber < PageCount; PageNumber++)
+                {
+                    /* Get the PFN entry for the current in-use page */
+                    Pfn = GetPfnEntry(BasePage + PageNumber);
+
+                    /* Ensure that the page is not already in-use */
+                    if(Pfn->u3.e2.ReferenceCount == 0)
+                    {
+                        /* Initialize the PFN entry to represent an in-use page and prevent it from being allocated */
+                        Pfn->PteAddress = MM::Paging::GetPteAddress(VirtualRangeStart);
+                        Pfn->u2.ShareCount++;
+                        Pfn->u3.e1.CacheAttribute = PfnCached;
+                        Pfn->u3.e1.PageLocation = ActiveAndValid;
+                        Pfn->u3.e2.ReferenceCount = 1;
+                        Pfn->u4.PteFrame = MM::Paging::GetPageFrameNumber(PointerPde);
+                    }
+                }
+                break;
+        }
+    }
+}
+
 /**
 * Scans memory descriptors provided by the boot loader.
 *