[FIX] move VMT allocator to specific HAL.

Signed-off-by: Amlal EL Mahrouss <amlalelmahrouss@icloud.com>

1 files changed, 115 insertions, 0 deletions

diff --git a/Kernel/HALKit/AMD64/HalPageAlloc.cxx b/Kernel/HALKit/AMD64/HalPageAlloc.cxx
new file mode 100644
index 00000000..d8c7696e
--- /dev/null
+++ b/Kernel/HALKit/AMD64/HalPageAlloc.cxx
@@ -0,0 +1,115 @@
+/* -------------------------------------------
+
+	Copyright ZKA Technologies
+
+------------------------------------------- */
+
+#include <ArchKit/ArchKit.hxx>
+
+#ifdef __NEWOS_AMD64__
+#include <HALKit/AMD64/HalPageAlloc.hxx>
+#elif defined(__NEWOS_ARM64__)
+#include <HALKit/ARM64/HalPageAlloc.hxx>
+#endif
+
+#include <NewKit/Defines.hxx>
+#include <NewKit/KernelCheck.hxx>
+
+Kernel::Boolean kAllocationInProgress = false;
+
+namespace Kernel
+{
+	constexpr auto cVMHMagic = 0xDEEFD00D;
+
+	namespace HAL
+	{
+		namespace Detail
+		{
+			struct VIRTUAL_MEMORY_HEADER
+			{
+				UInt32	Magic;
+				Boolean Present : 1;
+				Boolean ReadWrite : 1;
+				Boolean User : 1;
+				SizeT	Size;
+			};
+
+			struct VirtualMemoryHeaderTraits final
+			{
+				/// @brief Get next header.
+				/// @param current
+				/// @return
+				VIRTUAL_MEMORY_HEADER* Next(VIRTUAL_MEMORY_HEADER* current)
+				{
+					if (current->Magic != cVMHMagic)
+						current->Size = 8196;
+
+					return current + sizeof(VIRTUAL_MEMORY_HEADER) + current->Size;
+				}
+
+				/// @brief Get previous header.
+				/// @param current
+				/// @return
+				VIRTUAL_MEMORY_HEADER* Prev(VIRTUAL_MEMORY_HEADER* current)
+				{
+					if (current->Magic != cVMHMagic)
+						current->Size = 8196;
+
+					return current - sizeof(VIRTUAL_MEMORY_HEADER) - current->Size;
+				}
+			};
+		} // namespace Detail
+
+		/// @brief Allocates a new page of memory.
+		/// @param sz the size of it.
+		/// @param rw read/write flag.
+		/// @param user user flag.
+		/// @return the page table of it.
+		STATIC auto hal_try_alloc_new_page(Boolean rw, Boolean user, SizeT size) -> VoidPtr
+		{
+			if (kAllocationInProgress)
+				return nullptr;
+
+			kAllocationInProgress = true;
+
+			//! fetch from the start.
+			Detail::VIRTUAL_MEMORY_HEADER*	  vmHeader = reinterpret_cast<Detail::VIRTUAL_MEMORY_HEADER*>(kKernelVMTStart);
+			Detail::VirtualMemoryHeaderTraits traits;
+
+			while (vmHeader->Present &&
+				   vmHeader->Magic == cVMHMagic)
+			{
+				vmHeader = traits.Next(vmHeader);
+			}
+
+			vmHeader->Magic		= cVMHMagic;
+			vmHeader->Present	= true;
+			vmHeader->ReadWrite = rw;
+			vmHeader->User		= user;
+			vmHeader->Size		= size;
+
+			kAllocationInProgress = false;
+
+			return reinterpret_cast<VoidPtr>(vmHeader + sizeof(Detail::VIRTUAL_MEMORY_HEADER));
+		}
+
+		/// @brief Allocate a new page to be used by the OS.
+		/// @param rw read/write bit.
+		/// @param user user bit.
+		/// @return
+		auto hal_alloc_page(Boolean rw, Boolean user, SizeT size) -> VoidPtr
+		{
+			// Wait for a ongoing allocation to complete.
+			while (kAllocationInProgress)
+			{
+				(void)0;
+			}
+
+			if (size == 0)
+				++size;
+
+			// allocate new page.
+			return hal_try_alloc_new_page(rw, user, size);
+		}
+	} // namespace HAL
+} // namespace Kernel