kernel: virtual_mm: Simplify vmm implementation

2 files changed, 11 insertions, 126 deletions

diff --git a/kernel/include/mm/virtual_mm.h b/kernel/include/mm/virtual_mm.h
index f605cc7..4873a30 100644
--- a/kernel/include/mm/virtual_mm.h
+++ b/kernel/include/mm/virtual_mm.h
@@ -64,31 +64,6 @@
 #define ADD_ATTRIB(entry, attribute) (*entry |= (attribute))
 
 /*
- * Given a page table entry, it sets the frame to a newly allocated address,
- * and sets the present bit to false.
- */
-bool virtual_mm_allocate_page(uint32_t *pt_entry);
-
-/*
- * Given a page table entry, it sets the entry to 0 (therefore zero-ing the
- * frame and present bit).
- */
-bool virtual_mm_free_page(uint32_t *pt_entry);
-
-/*
- * Given a page table and virtual address, it returns a pointer to the page
- * table entry referenced by the virtual address.
- */
-uint32_t *virtual_mm_lookup_table(uint32_t *page_table, uint32_t virtual_addr);
-
-/*
- * Given a page directory and virtual address, it returns a pointer to the page
- * directory entry referenced by the virtual address.
- */
-uint32_t *virtual_mm_lookup_directory(uint32_t *page_directory,
-                                      uint32_t virtual_addr);
-
-/*
  * Loads a given page directory into CR0
  */
 void virtual_mm_load_page_directory(uint32_t *page_directory);
@@ -99,16 +74,6 @@ void virtual_mm_load_page_directory(uint32_t *page_directory);
 bool virtual_mm_switch_page_directory(uint32_t *page_directory);
 
 /*
- * Flushes the given TLB entry
- */
-void virtual_mm_flush_tlb_entry(uint32_t *virtual_addr);
-
-/*
- * Map a given physical address to a virtual address
- */
-bool virtual_mm_map_page(uint32_t *physical_addr, uint32_t *virtual_addr);
-
-/*
  * Initialize the virtual memory manager
  */
 void virtual_mm_initialize(void);
diff --git a/kernel/mm/virtual_mm/virtual_mm.c b/kernel/mm/virtual_mm/virtual_mm.c
index 7007350..d8d3d70 100644
--- a/kernel/mm/virtual_mm/virtual_mm.c
+++ b/kernel/mm/virtual_mm/virtual_mm.c
@@ -30,53 +30,10 @@ extern uint32_t kernel_end;
 
 uint32_t *current_page_directory = 0;
 
-bool
-virtual_mm_allocate_page(uint32_t *pt_entry)
-{
-  void *ptr = physical_mm_allocate_block();
-  if (!ptr)
-    return false;
-
-  ADD_ATTRIB(pt_entry, SET_PTE_FRAME((uint32_t) ptr));
-  ADD_ATTRIB(pt_entry, SET_PTE_PRESENT(1));
-
-  return true;
-}
-
-bool
-virtual_mm_free_page(uint32_t *pt_entry)
-{
-  void *ptr = (void *) GET_PTE_FRAME(pt_entry);
-  if (ptr)
-    physical_mm_free_block(ptr);
-
-  *pt_entry = 0;
-
-  return true;
-}
-
-ALWAYS_INLINE uint32_t *
-virtual_mm_lookup_table(uint32_t *page_table, uint32_t virtual_addr)
-{
-  if (page_table)
-    return &page_table[PAGE_TABLE_INDEX(virtual_addr)];
-
-  return NULL;
-}
-
-ALWAYS_INLINE uint32_t *
-virtual_mm_lookup_directory(uint32_t *page_directory, uint32_t virtual_addr)
-{
-  if (page_directory)
-    return &page_directory[PAGE_DIRECTORY_INDEX(virtual_addr)];
-
-  return NULL;
-}
-
 ALWAYS_INLINE void
 virtual_mm_load_page_directory(uint32_t *page_directory)
 {
-  __asm__("movl %0, %%cr3" ::"r"(page_directory));
+  __asm__("movl %0, %%eax" ::"r"(page_directory));
 }
 
 bool
@@ -90,43 +47,6 @@ virtual_mm_switch_page_directory(uint32_t *page_directory)
   return true;
 }
 
-/* TODO: I have absolutely _no_ idea if this works */
-void
-virtual_mm_flush_tlb_entry(uint32_t *virtual_addr)
-{
-  __asm__("cli;"
-          "invlpg (%0);"
-          "sti" ::"r"(virtual_addr));
-}
-
-bool
-virtual_mm_map_page(uint32_t *physical_addr, uint32_t *virtual_addr)
-{
-  uint32_t *pd_entry
-      = &current_page_directory[PAGE_DIRECTORY_INDEX((uint32_t) virtual_addr)];
-
-  /* If the page directory entry isn't present */
-  if (!PTE_IS_PRESENT(*pd_entry)) {
-    uint32_t *page_table = physical_mm_allocate_block();
-    if (!page_table)
-      return false;
-
-    *pd_entry = 0;
-    ADD_ATTRIB(pd_entry, SET_PDE_PRESENT(1));
-    ADD_ATTRIB(pd_entry, SET_PDE_WRITABLE(1));
-    ADD_ATTRIB(pd_entry, SET_PDE_FRAME((uint32_t) page_table));
-  }
-
-  uint32_t *page_table = (uint32_t *) GET_PDE_FRAME(pd_entry);
-  uint32_t *pt_entry = &page_table[PAGE_TABLE_INDEX((uint32_t) virtual_addr)];
-  *pt_entry = 0;
-
-  ADD_ATTRIB(pt_entry, SET_PTE_PRESENT(1));
-  ADD_ATTRIB(pt_entry, SET_PTE_FRAME((uint32_t) physical_addr));
-
-  return true;
-}
-
 ALWAYS_INLINE static void
 virtual_mm_enable_paging(void)
 {
@@ -149,15 +69,14 @@ virtual_mm_initialize(void)
   /* Identity map the first 4MiB (maps 4KiB 1024 times) */
   for (uint32_t i = 0, physical_addr = 0, virtual_addr = 0; i < 1024;
        i++, physical_addr += 4096, virtual_addr += 4096) {
-    uint32_t page = 0;
-    ADD_ATTRIB(&page, SET_PTE_PRESENT(1));
-    ADD_ATTRIB(&page, SET_PTE_FRAME(physical_addr));
+    uint32_t pt_entry = 0;
+    ADD_ATTRIB(&pt_entry, SET_PTE_PRESENT(1));
+    ADD_ATTRIB(&pt_entry, SET_PTE_WRITABLE(1));
+    ADD_ATTRIB(&pt_entry, SET_PTE_FRAME(physical_addr));
 
-    table[PAGE_TABLE_INDEX(virtual_addr)] = page;
+    table[PAGE_TABLE_INDEX(virtual_addr)] = pt_entry;
   }
-  printk("\n\ndebug",
-         "Table: 0x%x",
-         GET_PTE_FRAME(&table[PAGE_TABLE_INDEX(0x2000)]));
+  printk("debug", "Page table is at: 0x%x", table);
 
   uint32_t *page_directory = physical_mm_allocate_block();
   if (!page_directory)
@@ -166,13 +85,14 @@ virtual_mm_initialize(void)
   for (uint32_t i = 0; i < 1024; i++)
     page_directory[i] = 0;
 
-  current_page_directory = page_directory;
-
   uint32_t *pd_entry = &page_directory[PAGE_DIRECTORY_INDEX(0)];
   ADD_ATTRIB(pd_entry, SET_PDE_PRESENT(1));
   ADD_ATTRIB(pd_entry, SET_PDE_WRITABLE(1));
   ADD_ATTRIB(pd_entry, SET_PDE_FRAME((uint32_t) table));
 
-  virtual_mm_switch_page_directory(current_page_directory);
+  printk("debug", "Page directory is at: 0x%x", page_directory);
+  printk("debug", "pd_entry: 0x%x", pd_entry);
+
+  virtual_mm_switch_page_directory(page_directory);
   virtual_mm_enable_paging();
 }