From 4c6fd454d0b96734092661fb3739abe2a576c4ce Mon Sep 17 00:00:00 2001
From: Idan Horowitz <idan.horowitz@gmail.com>
Date: Sun, 24 Dec 2023 15:52:15 +0200
Subject: [PATCH] Kernel: Add MM helper for shrinking a virtual range to page
 boundaries

---
 Kernel/Memory/MemoryManager.h | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Kernel/Memory/MemoryManager.h b/Kernel/Memory/MemoryManager.h
index 04812fb93b4..168d72fffb0 100644
--- a/Kernel/Memory/MemoryManager.h
+++ b/Kernel/Memory/MemoryManager.h
@@ -321,4 +321,18 @@ inline ErrorOr<Memory::VirtualRange> expand_range_to_page_boundaries(FlatPtr add
     return Memory::VirtualRange { base, end - base.get() };
 }
 
+inline ErrorOr<Memory::VirtualRange> shrink_range_to_page_boundaries(FlatPtr address, size_t size)
+{
+    if ((address + size) < address)
+        return EINVAL;
+
+    auto base = TRY(Memory::page_round_up(address));
+    auto end = Memory::page_round_down(address + size);
+
+    if (end < base)
+        return EINVAL;
+
+    return Memory::VirtualRange { VirtualAddress(base), end - base };
+}
+
 }