From f2d5548d7a46d054f5015e29e90995a70106dc19 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Wed, 17 Nov 2021 19:31:30 +0100
Subject: [PATCH] Kernel: Add MemoryManager::copy_physical_page()

This is a handy helper that copies out the full contents of a physical
page into a caller-provided buffer. It uses quickmapping internally
(and takes the MM lock for the duration.)
---
 Kernel/Memory/MemoryManager.cpp | 8 ++++++++
 Kernel/Memory/MemoryManager.h   | 2 ++
 2 files changed, 10 insertions(+)

diff --git a/Kernel/Memory/MemoryManager.cpp b/Kernel/Memory/MemoryManager.cpp
index 2a5afa3688..c16984e955 100644
--- a/Kernel/Memory/MemoryManager.cpp
+++ b/Kernel/Memory/MemoryManager.cpp
@@ -1118,4 +1118,12 @@ void CommittedPhysicalPageSet::uncommit_one()
     MM.uncommit_user_physical_pages({}, 1);
 }
 
+void MemoryManager::copy_physical_page(PhysicalPage& physical_page, u8 page_buffer[PAGE_SIZE])
+{
+    SpinlockLocker locker(s_mm_lock);
+    auto* quickmapped_page = quickmap_page(physical_page);
+    memcpy(page_buffer, quickmapped_page, PAGE_SIZE);
+    unquickmap_page();
+}
+
 }
diff --git a/Kernel/Memory/MemoryManager.h b/Kernel/Memory/MemoryManager.h
index e1229d1bb5..edd6dd1640 100644
--- a/Kernel/Memory/MemoryManager.h
+++ b/Kernel/Memory/MemoryManager.h
@@ -240,6 +240,8 @@ public:
     PhysicalPageEntry& get_physical_page_entry(PhysicalAddress);
     PhysicalAddress get_physical_address(PhysicalPage const&);
 
+    void copy_physical_page(PhysicalPage&, u8 page_buffer[PAGE_SIZE]);
+
 private:
     MemoryManager();
     ~MemoryManager();