ptos/amd64+hal: Add page unmap interface

Signed-off-by: Chloe M <chloe@mensia.org>

service/ptos/arch/amd64/cpu/mmu.c

@@ -231,3 +231,30 @@ HalMmuMapPage(
     MdTlbFlushSingle(VirtualBase);
     return STATUS_SUCCESS;
 }
+
+PT_STATUS
+HalMmuUnmapPage(MMU_VAS *Vas, UPTR VirtualBase, MMU_PAGESIZE PageSize)
+{
+    UPTR *PageTable;
+    USIZE PageTableIndex;
+
+    if (Vas == NULL) {
+        return STATUS_INVALID_PARAM;
+    }
+
+    if (!MmuPageSizeValid(PageSize)) {
+        return STATUS_INVALID_PARAM;
+    }
+
+    PageTable = MmuPageMapExtract(Vas, VirtualBase, PAGEMAP_PML1, false);
+    if (PageTable == NULL) {
+        return STATUS_NOT_FOUND;
+    }
+
+    PageTableIndex = MmuPageMapIndex(VirtualBase, PAGEMAP_PML1);
+
+    /* Unmap and flush the TLB */
+    PageTable[PageTableIndex] = 0;
+    MdTlbFlushSingle(VirtualBase);
+    return STATUS_SUCCESS;
+}

service/ptos/head/hal/mmu.h

@@ -52,4 +52,16 @@ PT_STATUS HalMmuMapPage(
     MMU_PAGESIZE PageSize
 );
 
+/*
+ * Unmap a single page of memory
+ *
+ * @Vas:            Virtual address space to unmap within
+ * @VirtualBase:    Virtual address to unmap
+ * @PageSize:       Page size to unmap
+ */
+PT_STATUS HalMmuUnmapPage(
+    MMU_VAS *Vas, UPTR VirtualBase,
+    MMU_PAGESIZE PageSize
+);
+
 #endif  /* !_HAL_MMU_H_ */