From 9bc1abceff7d4d6b51bdb3cc5ea4b7b20b9fe83c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Lov=C3=A9n?= <thomasloven@gmail.com>
Date: Tue, 20 Feb 2018 21:58:14 +0100
Subject: [PATCH] VMM -- Touch and set page in one operation

---
 src/kernel/include/memory.h |  2 +-
 src/kernel/memory/memory.c  |  3 +--
 src/kernel/memory/vmm.c     | 16 +++++++++++++---
 src/kernel/memory/vmm.tt    | 28 +++++++++++++++++++++++-----
 4 files changed, 38 insertions(+), 11 deletions(-)

diff --git a/src/kernel/include/memory.h b/src/kernel/include/memory.h
index ffaccb8..4915980 100644
--- a/src/kernel/include/memory.h
+++ b/src/kernel/include/memory.h
@@ -41,7 +41,7 @@ uint64_t pmm_calloc();
 
 uint64_t vmm_get_page(uint64_t P4, uint64_t addr);
 #define PAGE_EXIST(p) ((p) != (uint64_t)-1)
-int vmm_set_page(uint64_t P4, uint64_t addr, uint64_t page, uint16_t flags);
+int vmm_set_page(uint64_t P4, uint64_t addr, uint64_t page, uint16_t flags, int touch);
 int touch_page(uint64_t P4, uint64_t addr, uint16_t flags);
 void free_page(uint64_t P4, uint64_t addr, int free);
 
diff --git a/src/kernel/memory/memory.c b/src/kernel/memory/memory.c
index 3d8ff36..56d62ba 100644
--- a/src/kernel/memory/memory.c
+++ b/src/kernel/memory/memory.c
@@ -25,8 +25,7 @@ void memory_init()
       if(!PAGE_EXIST(page) || !(page & PAGE_PRESENT))
       {
         uint16_t flags = PAGE_GLOBAL | PAGE_HUGE | PAGE_WRITE;
-        touch_page(kernel_P4, addr, flags);
-        vmm_set_page(kernel_P4, addr, p, flags | PAGE_PRESENT);
+        vmm_set_page(kernel_P4, addr, p, flags | PAGE_PRESENT, 1);
       }
 
       if(type == MMAP_FREE)
diff --git a/src/kernel/memory/vmm.c b/src/kernel/memory/vmm.c
index 754ae1e..859eb42 100644
--- a/src/kernel/memory/vmm.c
+++ b/src/kernel/memory/vmm.c
@@ -47,7 +47,7 @@ uint64_t vmm_get_page(uint64_t P4, uint64_t addr)
     return -1;
 }
 
-int vmm_set_page(uint64_t P4, uint64_t addr, uint64_t page, uint16_t flags)
+int vmm_set_page(uint64_t P4, uint64_t addr, uint64_t page, uint16_t flags, int touch)
 {
   if(flags & PAGE_HUGE)
   {
@@ -55,7 +55,12 @@ int vmm_set_page(uint64_t P4, uint64_t addr, uint64_t page, uint16_t flags)
           && P4e(P4, addr).present
           && P3e(P4, addr).present
         ))
-      return -1;
+    {
+      if(touch)
+        touch_page(P4, addr, flags);
+      else
+        return -1;
+    }
     if(P2e(P4, addr).present && !P2e(P4,addr).huge)
       return -1;
     P2e(P4, addr).value = page | flags;
@@ -63,7 +68,12 @@ int vmm_set_page(uint64_t P4, uint64_t addr, uint64_t page, uint16_t flags)
   }
 
   if(!page_exists(P4, addr))
-    return -1;
+  {
+    if(touch)
+      touch_page(P4, addr, flags);
+    else
+      return -1;
+  }
 
   P1e(P4, addr).value = page | flags;
   return 0;
diff --git a/src/kernel/memory/vmm.tt b/src/kernel/memory/vmm.tt
index 272234d..57c25f0 100644
--- a/src/kernel/memory/vmm.tt
+++ b/src/kernel/memory/vmm.tt
@@ -82,7 +82,7 @@ TEST(set_page_sets_page)
 {
   BUILD_PT(0,0,0);
 
-  vmm_set_page(P4, 0, 0x1234567890ABC000, PAGE_PRESENT);
+  vmm_set_page(P4, 0, 0x1234567890ABC000, PAGE_PRESENT, 0);
 
   ASSERT_EQ_PTR(p1[0], 0x1234567890ABC000 | PAGE_PRESENT);
 }
@@ -90,7 +90,7 @@ TEST(set_page_returns_success_if_working)
 {
   BUILD_PT(0,0,0);
 
-  int retval = vmm_set_page(P4, 0, 0x1234567890ABC000, PAGE_PRESENT);
+  int retval = vmm_set_page(P4, 0, 0x1234567890ABC000, PAGE_PRESENT, 0);
 
   ASSERT_EQ_INT(retval, 0);
 }
@@ -99,16 +99,34 @@ TEST(set_page_fails_if_PT_missing)
   BUILD_PT(0,0,0);
   p3[0] = (uint64_t)p2;
 
-  int retval = vmm_set_page(P4, 0, 0x1234567890ABC000, PAGE_PRESENT);
+  int retval = vmm_set_page(P4, 0, 0x1234567890ABC000, PAGE_PRESENT, 0);
 
   ASSERT_NEQ_INT(retval, 0);
 }
+TEST(set_page_does_not_fail_if_PT_missing_but_touch_flag_is_set)
+{
+  BUILD_PT(0,0,0);
+  p3[0] = (uint64_t)p2;
+
+  int retval = vmm_set_page(P4, 0, 0x1234567890ABC000, PAGE_PRESENT, 1);
+
+  ASSERT_EQ_INT(retval, 0);
+}
+TEST(set_page_makes_P3_if_PT_missing_but_touch_flag_is_set)
+{
+  BUILD_PT(0,0,0);
+  p3[0] = (uint64_t)p2;
+
+  vmm_set_page(P4, 0, 0x1234567890ABC000, PAGE_PRESENT, 1);
+
+  ASSERT_EQ_INT(p3[0] & PAGE_PRESENT, PAGE_PRESENT);
+}
 TEST(set_page_sets_2mb_pages)
 {
   p4[1] = (uint64_t)p3; p4[1] |= PAGE_PRESENT;
   p3[2] = (uint64_t)p2; p3[2] |= PAGE_PRESENT;
 
-  vmm_set_page(P4, (1UL<<39)+(2UL<<30)+(3UL<<21), 0x1234567890A00000, PAGE_HUGE | PAGE_PRESENT);
+  vmm_set_page(P4, (1UL<<39)+(2UL<<30)+(3UL<<21), 0x1234567890A00000, PAGE_HUGE | PAGE_PRESENT, 0);
 
   ASSERT_EQ_PTR(p2[3], 0x1234567890A00000 | PAGE_HUGE | PAGE_PRESENT);
 }
@@ -116,7 +134,7 @@ TEST(set_page_does_not_overwrite_4kb_pages_with_2mb)
 {
   BUILD_PT(0,0,0);
 
-  int retval = vmm_set_page(P4, 0, 0, PAGE_HUGE | PAGE_PRESENT);
+  int retval = vmm_set_page(P4, 0, 0, PAGE_HUGE | PAGE_PRESENT, 0);
 
   ASSERT_NEQ_INT(retval, 0);
 }