From 4bf1a72d2158f7a1531f643444cb896558094973 Mon Sep 17 00:00:00 2001
From: Andreas Kling <awesomekling@gmail.com>
Date: Sun, 3 Nov 2019 20:59:54 +0100
Subject: [PATCH] Kernel: Teach Region how to remap itself

Now remapping (i.e flushing kernel metadata to the CPU page tables)
is done by simply calling Region::remap().
---
 Kernel/Process.cpp          |  4 ++--
 Kernel/SharedBuffer.cpp     |  2 +-
 Kernel/VM/InodeVMObject.cpp | 10 ++++------
 Kernel/VM/MemoryManager.cpp |  7 -------
 Kernel/VM/MemoryManager.h   |  2 --
 Kernel/VM/Region.cpp        |  8 +++++++-
 Kernel/VM/Region.h          |  1 +
 7 files changed, 15 insertions(+), 19 deletions(-)

diff --git a/Kernel/Process.cpp b/Kernel/Process.cpp
index 74a643ee6e4..1ff6fd85864 100644
--- a/Kernel/Process.cpp
+++ b/Kernel/Process.cpp
@@ -283,7 +283,7 @@ int Process::sys$mprotect(void* addr, size_t size, int prot)
     if (!region)
         return -EINVAL;
     region->set_writable(prot & PROT_WRITE);
-    MM.remap_region(page_directory(), *region);
+    region->remap();
     return 0;
 }
 
@@ -885,7 +885,7 @@ void create_signal_trampolines()
     memcpy(code_ptr, trampoline, trampoline_size);
 
     trampoline_region->set_writable(false);
-    MM.remap_region(*trampoline_region->page_directory(), *trampoline_region);
+    trampoline_region->remap();
 }
 
 int Process::sys$restore_signal_mask(u32 mask)
diff --git a/Kernel/SharedBuffer.cpp b/Kernel/SharedBuffer.cpp
index d95e9ba2243..87b119cad02 100644
--- a/Kernel/SharedBuffer.cpp
+++ b/Kernel/SharedBuffer.cpp
@@ -155,7 +155,7 @@ void SharedBuffer::seal()
     for (auto& ref : m_refs) {
         if (ref.region) {
             ref.region->set_writable(false);
-            MM.remap_region(*ref.region->page_directory(), *ref.region);
+            ref.region->remap();
         }
     }
 }
diff --git a/Kernel/VM/InodeVMObject.cpp b/Kernel/VM/InodeVMObject.cpp
index e96e44b4733..93bcc65bf3f 100644
--- a/Kernel/VM/InodeVMObject.cpp
+++ b/Kernel/VM/InodeVMObject.cpp
@@ -47,9 +47,8 @@ void InodeVMObject::inode_size_changed(Badge<Inode>, size_t old_size, size_t new
     m_physical_pages.resize(new_page_count);
 
     // FIXME: Consolidate with inode_contents_changed() so we only do a single walk.
-    for_each_region([](Region& region) {
-        ASSERT(region.page_directory());
-        MM.remap_region(*region.page_directory(), region);
+    for_each_region([](auto& region) {
+        region.remap();
     });
 }
 
@@ -99,9 +98,8 @@ void InodeVMObject::inode_contents_changed(Badge<Inode>, off_t offset, ssize_t s
 #endif
 
     // FIXME: Consolidate with inode_size_changed() so we only do a single walk.
-    for_each_region([](Region& region) {
-        ASSERT(region.page_directory());
-        MM.remap_region(*region.page_directory(), region);
+    for_each_region([](auto& region) {
+        region.remap();
     });
 }
 
diff --git a/Kernel/VM/MemoryManager.cpp b/Kernel/VM/MemoryManager.cpp
index bb3adcfe889..67cddbf1446 100644
--- a/Kernel/VM/MemoryManager.cpp
+++ b/Kernel/VM/MemoryManager.cpp
@@ -673,13 +673,6 @@ void MemoryManager::unquickmap_page()
     m_quickmap_in_use = false;
 }
 
-void MemoryManager::remap_region(PageDirectory& page_directory, Region& region)
-{
-    InterruptDisabler disabler;
-    ASSERT(region.page_directory() == &page_directory);
-    map_region_at_address(page_directory, region, region.vaddr());
-}
-
 void MemoryManager::map_region_at_address(PageDirectory& page_directory, Region& region, VirtualAddress vaddr)
 {
     InterruptDisabler disabler;
diff --git a/Kernel/VM/MemoryManager.h b/Kernel/VM/MemoryManager.h
index 7a77933127d..38ed88ba42b 100644
--- a/Kernel/VM/MemoryManager.h
+++ b/Kernel/VM/MemoryManager.h
@@ -64,8 +64,6 @@ public:
     void deallocate_user_physical_page(PhysicalPage&&);
     void deallocate_supervisor_physical_page(PhysicalPage&&);
 
-    void remap_region(PageDirectory&, Region&);
-
     void map_for_kernel(VirtualAddress, PhysicalAddress, bool cache_disabled = false);
 
     OwnPtr<Region> allocate_kernel_region(size_t, const StringView& name, bool user_accessible = false, bool should_commit = true);
diff --git a/Kernel/VM/Region.cpp b/Kernel/VM/Region.cpp
index e1901350864..c47d1c8eb48 100644
--- a/Kernel/VM/Region.cpp
+++ b/Kernel/VM/Region.cpp
@@ -75,7 +75,7 @@ NonnullOwnPtr<Region> Region::clone()
 #endif
     // Set up a COW region. The parent (this) region becomes COW as well!
     ensure_cow_map().fill(true);
-    MM.remap_region(current->process().page_directory(), *this);
+    remap();
     auto clone_region = Region::create_user_accessible(m_range, m_vmobject->clone(), m_offset_in_vmo, m_name, m_access);
     clone_region->ensure_cow_map();
     return clone_region;
@@ -220,3 +220,9 @@ void Region::map(PageDirectory& page_directory)
 {
     MM.map_region_at_address(page_directory, *this, vaddr());
 }
+
+void Region::remap()
+{
+    ASSERT(m_page_directory);
+    MM.map_region_at_address(*m_page_directory, *this, vaddr());
+}
diff --git a/Kernel/VM/Region.h b/Kernel/VM/Region.h
index cc8c2766405..104661bfad3 100644
--- a/Kernel/VM/Region.h
+++ b/Kernel/VM/Region.h
@@ -121,6 +121,7 @@ public:
     };
     void unmap(ShouldDeallocateVirtualMemoryRange = ShouldDeallocateVirtualMemoryRange::Yes);
 
+    void remap();
     void remap_page(size_t index);
 
     // For InlineLinkedListNode