From 1ad156902ae1c251f8d6641b58668a1db50c0512 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Lov=C3=A9n?= <thomasloven@gmail.com>
Date: Sat, 23 Dec 2017 22:01:07 +0100
Subject: [PATCH] VMM - get_page ignores flags -- also restructuring - bad
 Thomas!

---
 src/kernel/memory/vmm.c  | 35 ++++++++++++++++++++---------------
 src/kernel/memory/vmm.tt | 14 ++++++++++++++
 2 files changed, 34 insertions(+), 15 deletions(-)

diff --git a/src/kernel/memory/vmm.c b/src/kernel/memory/vmm.c
index d5dbf47..079ec35 100644
--- a/src/kernel/memory/vmm.c
+++ b/src/kernel/memory/vmm.c
@@ -1,26 +1,31 @@
 #include <memory.h>
 
 #define FLAGS_MASK (PAGE_SIZE-1)
+#define MASK_FLAGS(addr) ((uintptr_t)addr & ~FLAGS_MASK)
 
-struct PT {
-  struct PT *p[ENTRIES_PER_PT];
-}__attribute__((packed));
+union PTE {
+  uint64_t value;
+  struct {
+    uintptr_t flags:12;
+  };
+};
 
-#define P(pt) ((struct PT *)((uintptr_t)pt & ~(FLAGS_MASK)))
+typedef union PTE PT[512];
 
-#define P3(pt, addr) (P(pt)->p[P4_OFFSET(addr)])
-#define P2(pt, addr) (P(P3(pt, addr))->p[P3_OFFSET(addr)])
-#define P1(pt, addr) (P(P2(pt, addr))->p[P2_OFFSET(addr)])
-#define P0(pt, addr) (P(P1(pt, addr))->p[P1_OFFSET(addr)])
+#define PT(ptr) ((PT *)MASK_FLAGS(ptr->value))
+#define P4e(pt, addr) (((PT *)pt)[P4_OFFSET(addr)])
+#define P3e(pt, addr) PT(P4e(pt, addr))[P3_OFFSET(addr)]
+#define P2e(pt, addr) PT(P3e(pt, addr))[P2_OFFSET(addr)]
+#define P1e(pt, addr) PT(P2e(pt, addr))[P1_OFFSET(addr)]
 
-
-uintptr_t vmm_get_page(uintptr_t *P4, uintptr_t addr)
+uintptr_t vmm_get_page(void *P4, uintptr_t addr)
 {
   if(P4
-      && P3(P4, addr)
-      && P2(P4, addr)
-      && P1(P4, addr)
+      && P4e(P4, addr)
+      && P3e(P4, addr)
+      && P2e(P4, addr)
     )
-    return (uintptr_t)P0(P4, addr);
-  return 0;
+    return MASK_FLAGS(P1e(P4, addr)->value);
+  else
+    return 0;
 }
diff --git a/src/kernel/memory/vmm.tt b/src/kernel/memory/vmm.tt
index 469f2fc..9e1fe0b 100644
--- a/src/kernel/memory/vmm.tt
+++ b/src/kernel/memory/vmm.tt
@@ -30,3 +30,17 @@ TEST(get_page_returns_correct_address)
 
   ASSERT_EQ_PTR(ret, 0x1234567890ABC000);
 }
+TEST(get_page_ignores_flags)
+{
+  p4[0] = (uintptr_t)p3;
+  p4[0] |= 0x123;
+  p3[0] = (uintptr_t)p2;
+  p3[0] |= 0x456;
+  p2[0] = (uintptr_t)p1;
+  p2[0] |= 0x789;
+  p1[0] = 0x1234567890ABCDEF;
+
+  uintptr_t ret = vmm_get_page(p4, 0);
+
+  ASSERT_EQ_PTR(ret, 0x1234567890ABC000);
+}