core: hle: kernel: k_page_buffer: Add KPageBuffer primitive.

src/core/CMakeLists.txt

@@ -207,6 +207,7 @@ add_library(core STATIC
     hle/kernel/k_memory_region.h
     hle/kernel/k_memory_region_type.h
     hle/kernel/k_page_bitmap.h
+    hle/kernel/k_page_buffer.h
     hle/kernel/k_page_heap.cpp
     hle/kernel/k_page_heap.h
     hle/kernel/k_page_linked_list.h

src/core/hle/kernel/k_page_buffer.h

@@ -0,0 +1,34 @@
+// Copyright 2022 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <array>
+
+#include "common/alignment.h"
+#include "common/assert.h"
+#include "common/common_types.h"
+#include "core/core.h"
+#include "core/device_memory.h"
+#include "core/hle/kernel/memory_types.h"
+
+namespace Kernel {
+
+class KPageBuffer final : public KSlabAllocated<KPageBuffer> {
+public:
+    KPageBuffer() = default;
+
+    static KPageBuffer* FromPhysicalAddress(Core::System& system, PAddr phys_addr) {
+        ASSERT(Common::IsAligned(phys_addr, PageSize));
+        return reinterpret_cast<KPageBuffer*>(system.DeviceMemory().GetPointer(phys_addr));
+    }
+
+private:
+    [[maybe_unused]] alignas(PageSize) std::array<u8, PageSize> m_buffer{};
+};
+
+static_assert(sizeof(KPageBuffer) == PageSize);
+static_assert(alignof(KPageBuffer) == PageSize);
+
+} // namespace Kernel