From ce937c808841b40f23e898e9aa71071860b6068a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Lov=C3=A9n?= <thomasloven@gmail.com>
Date: Wed, 3 Jan 2018 14:16:02 +0100
Subject: [PATCH] VMM - free_page does not unset P2 entry if P1 is not empty

---
 src/kernel/memory/vmm.c  | 27 +++++++++++++++++----------
 src/kernel/memory/vmm.tt | 11 +++++++++++
 2 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/src/kernel/memory/vmm.c b/src/kernel/memory/vmm.c
index 6acfd13..4ba7afc 100644
--- a/src/kernel/memory/vmm.c
+++ b/src/kernel/memory/vmm.c
@@ -98,21 +98,28 @@ int touch_page(void *P4, uintptr_t addr, uint16_t flags)
 
 void free_page(void *P4, uintptr_t addr, int free)
 {
-  (void)free;
   if(!page_exists(P4, addr))
     return;
-  P1e(P4, addr).value = 0;
-
-  if(!free) return;
 
   union PTE *pt;
 
-  pt = PT(P2e(P4, addr).value);
-  for(int i = 0; i < ENTRIES_PER_PT; i++)
-    if(pt[i].value)
-      return;
-  pmm_free(MASK_FLAGS(P2e(P4, addr).value));
-  P2e(P4, addr).value = 0;
+  if(P2e(P4, addr).huge)
+  {
+    P2e(P4, addr).value = 0;
+
+    if(!free) return;
+  } else {
+    P1e(P4, addr).value = 0;
+
+    if(!free) return;
+
+    pt = PT(P2e(P4, addr).value);
+    for(int i = 0; i < ENTRIES_PER_PT; i++)
+      if(pt[i].value)
+        return;
+    pmm_free(MASK_FLAGS(P2e(P4, addr).value));
+    P2e(P4, addr).value = 0;
+  }
 
   pt = PT(P3e(P4, addr).value);
   for(int i = 0; i < ENTRIES_PER_PT; i++)
diff --git a/src/kernel/memory/vmm.tt b/src/kernel/memory/vmm.tt
index b3e729b..b08f308 100644
--- a/src/kernel/memory/vmm.tt
+++ b/src/kernel/memory/vmm.tt
@@ -196,6 +196,17 @@ TEST(free_page_does_not_unset_P2_entry_if_P1_is_not_empty)
 
   ASSERT_NEQ_PTR(p2[3], 0);
 }
+TEST(free_page_does_not_stop_if_P2_pointed_page_is_not_empty)
+{
+  BUILD_PT(1,2,3);
+  p2[3] |= PAGE_HUGE;
+  p1[4] = PAGE_PRESENT;
+  p1[0] = PAGE_PRESENT;
+
+  free_page(p4, ADDR1234, 1);
+
+  ASSERT_EQ_PTR(p2[3], 0);
+}
 
 uintptr_t freed[] = {0,0,0,0,0};
 void pmm_free(uintptr_t page)