feat: Implemented `HalPagingMgr` for AArch64.

Signed-off-by: Amlal El Mahrouss <amlal@nekernel.org>

3 files changed, 49 insertions, 2 deletions

diff --git a/compile_flags.txt b/compile_flags.txt
index 2005c689..12740fa6 100644
--- a/compile_flags.txt
+++ b/compile_flags.txt
@@ -19,6 +19,7 @@
 -I./
 -std=c++20
 -D__NE_AMD64__
+-D__NE_ARM64__
 -D__NEOSKRNL__
 -D__NE_ED__
 -xc++
diff --git a/dev/boot/src/BootThread.cc b/dev/boot/src/BootThread.cc
index c4a55ae1..377e6e3a 100644
--- a/dev/boot/src/BootThread.cc
+++ b/dev/boot/src/BootThread.cc
@@ -107,6 +107,10 @@ BootThread::BootThread(VoidPtr blob) : fStartAddress(nullptr), fBlob(blob) {
             .Write("\r");
 
         /// @note .text region shall be marked as executable on ARM.
+
+#ifdef __NE_ARM64__
+
+#endif
       } else if (StrCmp(sectionForBootZ, sect->Name) == 0) {
         struct HANDOVER_INFORMATION_STUB {
           UInt64 HandoverMagic;
diff --git a/dev/kernel/HALKit/ARM64/HalPagingMgr.cc b/dev/kernel/HALKit/ARM64/HalPagingMgr.cc
index faad6778..953cee3b 100644
--- a/dev/kernel/HALKit/ARM64/HalPagingMgr.cc
+++ b/dev/kernel/HALKit/ARM64/HalPagingMgr.cc
@@ -13,15 +13,57 @@
 namespace Kernel::HAL {
 typedef UInt32 PageTableIndex;
 
+EXTERN_C UIntPtr mm_get_page_addr(VoidPtr virtual_address) {
+  if (!virtual_address) return 0;
+
+  UInt64 ttbr0_val = 0;
+
+  asm volatile("mrs %0, ttbr0_el1" : "=r"(ttbr0_val));
+  volatile UInt64* l1_table = reinterpret_cast<volatile UInt64*>(ttbr0_val);
+
+  UInt64 l1_idx = (reinterpret_cast<UIntPtr>(virtual_address) >> 39) & 0x1FF;
+  UInt64 l2_idx = (reinterpret_cast<UIntPtr>(virtual_address) >> 30) & 0x1FF;
+  UInt64 l3_idx = (reinterpret_cast<UIntPtr>(virtual_address) >> 21) & 0x1FF;
+
+  if (!l1_table[l1_idx]) return 0;
+
+  volatile UInt64* l2_table = reinterpret_cast<volatile UInt64*>(l1_table[l1_idx] & ~0xFFFUL);
+
+  if (!l2_table[l2_idx]) return 0;
+
+  volatile UInt64* l3_table = reinterpret_cast<volatile UInt64*>(l2_table[l2_idx] & ~0xFFFUL);
+
+  if (!l3_table[l3_idx]) return 0;
+
+  return (l3_table[l3_idx] & ~0xFFFUL);
+}
+
 /// @brief Maps or allocates a page from virtual_address.
 /// @param virtual_address a valid virtual address.
 /// @param phys_addr point to physical address.
 /// @param flags the flags to put on the page.
 /// @return Status code of page manipulation process.
 EXTERN_C Int32 mm_map_page(VoidPtr virtual_address, VoidPtr physical_address, UInt32 flags) {
-  if (!virtual_address || !flags) return kErrorInvalidData;
+  if (!virtual_address || !flags || !physical_address) return kErrorInvalidData;
+
+  UInt64 ttbr0_val = 0;
+
+  asm volatile("mrs %0, ttbr0_el1" : "=r"(ttbr0_val));
+  volatile UInt64* l1_table = reinterpret_cast<volatile UInt64*>(ttbr0_val);
+
+  UInt64 l1_idx = (reinterpret_cast<UIntPtr>(virtual_address) >> 39) & 0x1FF;
+  UInt64 l2_idx = (reinterpret_cast<UIntPtr>(virtual_address) >> 30) & 0x1FF;
+  UInt64 l3_idx = (reinterpret_cast<UIntPtr>(virtual_address) >> 21) & 0x1FF;
+
+  if (!l1_table[l1_idx]) return kErrorInvalidData;
+
+  volatile UInt64* l2_table = reinterpret_cast<volatile UInt64*>(l1_table[l1_idx] & ~0xFFFUL);
+
+  if (!l2_table[l2_idx]) return kErrorInvalidData;
+
+  volatile UInt64* l3_table = reinterpret_cast<volatile UInt64*>(l2_table[l2_idx] & ~0xFFFUL);
 
-  NE_UNUSED(physical_address);
+  l3_table[l3_idx] = (reinterpret_cast<UInt64>(physical_address) & ~0xFFFUL) | flags;
 
   return kErrorSuccess;
 }