From 1d4b689215654d68f6312318d0c134ab649195bc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Lov=C3=A9n?= <thomasloven@gmail.com>
Date: Wed, 27 Dec 2017 23:08:41 +0100
Subject: [PATCH] VMM - touch_page adds P3

---
 src/kernel/memory/vmm.c  | 10 ++++++++++
 src/kernel/memory/vmm.tt | 16 ++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/src/kernel/memory/vmm.c b/src/kernel/memory/vmm.c
index 15447d6..fccb76c 100644
--- a/src/kernel/memory/vmm.c
+++ b/src/kernel/memory/vmm.c
@@ -49,3 +49,13 @@ int vmm_set_page(void *P4, uintptr_t addr, uintptr_t page, uint16_t flags)
   P1e(P4, addr).value = page | flags;
   return 0;
 }
+
+int touch_page(void *P4, uintptr_t addr, uint16_t flags)
+{
+  (void)flags;
+  if(!P4) return -1;
+  if(!P4e(P4, addr).present)
+    P4e(P4, addr).value = pmm_alloc();
+
+  return 0;
+}
diff --git a/src/kernel/memory/vmm.tt b/src/kernel/memory/vmm.tt
index 3388f8a..6da6503 100644
--- a/src/kernel/memory/vmm.tt
+++ b/src/kernel/memory/vmm.tt
@@ -114,3 +114,19 @@ TEST(set_page_fails_if_PT_missing)
 
   ASSERT_NEQ_INT(retval, 0);
 }
+
+uintptr_t pmm_alloc()
+{
+  uintptr_t *pages[] = {p3, p2, p1};
+  static int counter=0;
+  return (uintptr_t)pages[counter++];
+}
+
+TEST(touch_page_adds_P3)
+{
+  p4[0] = 0;
+
+  touch_page(p4, 0, 0);
+
+  ASSERT_NEQ_PTR(p4[0], 0);
+}