MemoryManager: Add get_kernel_mapping_for_frames()

This function allocates a continuous range of VM and maps the physical frames passed to said VM range.

kernel/src/memory/MemoryManager.cpp

@@ -247,6 +247,32 @@ namespace MemoryManager
         return start;
     }
 
+    Result<u64> get_kernel_mapping_for_frames(u64 phys, usize count, int flags)
+    {
+        u64 start = TRY(KernelVM::alloc_several_pages(count));
+
+        usize pages_mapped = 0;
+
+        auto guard = make_scope_guard([=, &pages_mapped] {
+            KernelVM::free_several_pages(start, pages_mapped);
+            unmap_weak(start, pages_mapped);
+        });
+
+        u64 virt = start;
+
+        while (pages_mapped < count)
+        {
+            TRY(MMU::map(virt, phys, flags));
+            virt += ARCH_PAGE_SIZE;
+            phys += ARCH_PAGE_SIZE;
+            pages_mapped++;
+        }
+
+        guard.deactivate();
+
+        return start;
+    }
+
     Result<void> unmap_owned(u64 virt, usize count)
     {
         CHECK_PAGE_ALIGNED(virt);

kernel/src/memory/MemoryManager.h

@@ -25,6 +25,8 @@ namespace MemoryManager
     Result<u64> alloc_at(u64 virt, usize count, int flags);
     Result<u64> alloc_for_kernel(usize count, int flags);
 
+    Result<u64> get_kernel_mapping_for_frames(u64 phys, usize count, int flags);
+
     Result<void> unmap_owned(u64 virt, usize count);
     Result<void> unmap_owned_and_free_vm(u64 virt, usize count);
     Result<void> unmap_weak(u64 virt, usize count);