VMM -- Know what? Let's ignore huge pages for simplicity

src/kernel/memory/memory.c

@@ -24,7 +24,7 @@ void memory_init()
       uint64_t page = vmm_get_page(kernel_P4, addr);
       if(!PAGE_EXIST(page) || !(page & PAGE_PRESENT))
       {
-        uint16_t flags = PAGE_GLOBAL | PAGE_HUGE | PAGE_WRITE;
+        uint16_t flags = PAGE_GLOBAL | PAGE_WRITE;
         vmm_set_page(kernel_P4, addr, p, flags | PAGE_PRESENT, 1);
       }
 

src/kernel/memory/vmm.c

@@ -39,8 +39,6 @@ uint64_t vmm_get_page(uint64_t P4, uint64_t addr)
 {
   if(page_exists(P4, addr))
   {
-    if(P2E.huge)
-      return P2E.value;
     return P1E.value;
   }
   return -1;
@@ -48,22 +46,6 @@ uint64_t vmm_get_page(uint64_t P4, uint64_t addr)
 
 int vmm_set_page(uint64_t P4, uint64_t addr, uint64_t page, uint16_t flags, int touch)
 {
-  if(flags & PAGE_HUGE)
-  {
-    if(!(P4 && P4E.present && P3E.present))
-    {
-      if(!touch)
-        return -1;
-      touch_page(P4, addr, flags);
-    }
-
-    // Don't overwrite a non-huge page with a huge one
-    if(P2E.present && !P2E.huge)
-      return -1;
-    P2E.value = page | flags;
-    return 0;
-  }
-
   if(!page_exists(P4, addr))
   {
     if(!touch)
@@ -79,9 +61,6 @@ int touch_page(uint64_t P4, uint64_t addr, uint16_t flags)
 {
   if(!P4) return -1;
 
-  int huge=(flags & PAGE_HUGE)?1:0;
-  flags ^= PAGE_HUGE*huge;
-
   if((!P4E.present) && (!(P4E.value = pmm_calloc())))
     return -1;
   P4E.value |= flags | PAGE_PRESENT;
@@ -90,8 +69,6 @@ int touch_page(uint64_t P4, uint64_t addr, uint16_t flags)
     return -1;
   P3E.value |= flags | PAGE_PRESENT;
 
-  if(huge) return 0;
-
   if((!P2E.present) && (!(P2E.value = pmm_calloc())))
     return -1;
   P2E.value |= flags | PAGE_PRESENT;
@@ -106,25 +83,17 @@ void free_page(uint64_t P4, uint64_t addr, int free)
 
   union PTE *pt;
 
-  if(P2E.huge)
+  P1E.value = 0;
-  {
-    P2E.value = 0;
 
-    if(!free)
+  if(!free)
+    return;
+
+  pt = PT(P2E.value);
+  for(int i = 0; i < ENTRIES_PER_PT; i++)
+    if(pt[i].value)
       return;
-  } else {
+  pmm_free(MASK_FLAGS(P2E.value));
-    P1E.value = 0;
+  P2E.value = 0;
-
-    if(!free)
-      return;
-
-    pt = PT(P2E.value);
-    for(int i = 0; i < ENTRIES_PER_PT; i++)
-      if(pt[i].value)
-        return;
-    pmm_free(MASK_FLAGS(P2E.value));
-    P2E.value = 0;
-  }
 
   pt = PT(P3E.value);
   for(int i = 0; i < ENTRIES_PER_PT; i++)

src/kernel/memory/vmm.tt

@@ -68,15 +68,6 @@ TEST(get_page_fails_if_PTE_not_present)
 
   ASSERT_EQ_PTR(ret, -1);
 }
-TEST(get_page_gets_2mb_pages)
-{
-  p4[1] = (uint64_t)p3; p4[1] |= PAGE_PRESENT;
-  p3[2] = (uint64_t)p2; p3[2] |= PAGE_PRESENT;
-  p2[3] = 0x1234567890A00000 | PAGE_HUGE | PAGE_PRESENT;
-
-  uint64_t ret = vmm_get_page(P4, ADDR1234);
-  ASSERT_EQ_PTR(ret, 0x1234567890A00000 | PAGE_HUGE | PAGE_PRESENT);
-}
 
 TEST(set_page_sets_page)
 {
@@ -121,23 +112,6 @@ TEST(set_page_makes_P3_if_PT_missing_but_touch_flag_is_set)
 
   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, 0);
-
-  ASSERT_EQ_PTR(p2[3], 0x1234567890A00000 | PAGE_HUGE | PAGE_PRESENT);
-}
-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, 0);
-
-  ASSERT_NEQ_INT(retval, 0);
-}
 
 uint64_t pmm_calloc()
 {
@@ -177,11 +151,6 @@ TEST(touch_page_fails_if_out_of_pages)
   int retval = touch_page(P4, 0, 0);
   ASSERT_NEQ_INT(retval, 0);
 }
-TEST(touch_page_stops_at_P2_for_huge_pages)
-{
-  touch_page(P4, 0, PAGE_HUGE);
-  ASSERT_EQ_PTR(p2[0], 0);
-}
 
 TEST(free_page_unsets_page)
 {
@@ -220,17 +189,6 @@ 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);
-}
 
 uint64_t freed[] = {0,0,0,0,0};
 void pmm_free(uint64_t page)