feat: add support for shutdown/reboot via UEFI Runtime Services

kernel/src/Memory/Paging.cpp

@@ -267,4 +267,34 @@ namespace Memory::VMM {
     std::uint64_t Paging::GetPhysAddr(std::uint64_t virtualAddress) {
         return GetPhysAddr((std::uint64_t)PML4, virtualAddress, false);
     }
+
+    void Paging::MapEfiRuntime(limine_efi_memmap_response* efiMemmap) {
+        if (!efiMemmap) return;
+
+        auto* base = (uint8_t*)efiMemmap->memmap;
+        uint64_t descSize = efiMemmap->desc_size;
+        uint64_t count = efiMemmap->memmap_size / descSize;
+
+        struct EfiMemDesc {
+            uint32_t Type;
+            uint64_t PhysicalStart;
+            uint64_t VirtualStart;
+            uint64_t NumberOfPages;
+            uint64_t Attribute;
+        };
+
+        static constexpr uint64_t EFI_MEMORY_RUNTIME = 0x8000000000000000ULL;
+
+        for (uint64_t i = 0; i < count; i++) {
+            auto* desc = (EfiMemDesc*)(base + i * descSize);
+            if (desc->Attribute & EFI_MEMORY_RUNTIME) {
+                for (uint64_t p = 0; p < desc->NumberOfPages; p++) {
+                    uint64_t addr = desc->PhysicalStart + p * 0x1000;
+                    Map(addr, addr);
+                }
+            }
+        }
+
+        FlushTLB();
+    }
 };

kernel/src/Memory/Paging.hpp

@@ -108,10 +108,18 @@ public:
 
         // Map a page into an arbitrary PML4 with User + Write-Combining attributes.
         static void MapUserInWC(std::uint64_t pml4Phys, std::uint64_t physicalAddress, std::uint64_t virtualAddress);
+
+        // Identity-map EFI runtime service regions so firmware code can
+        // reference its own data at physical addresses.
+        void MapEfiRuntime(limine_efi_memmap_response* efiMemmap);
     };
 
     extern Paging* g_paging;
 
     extern "C" uint64_t GetCR3();
     extern "C" void LoadCR3(PageTable* PML4);
+
+    inline void FlushTLB() {
+        asm volatile("mov %%cr3, %%rax; mov %%rax, %%cr3" ::: "rax", "memory");
+    }
 };