start reworking memory. Again.

src/mem.c

@@ -5,10 +5,6 @@
 #include "mem.h"
 #include "serial.h"
 
-// page_directory is currently defined once and should not be touched
-// later. It must be page aligned for the MMU to read properly
-page_directory_entry page_directory[1024] __attribute__((aligned(4096)));
-
 // populate_page_table makes a page table at `table` mapping `num`
 // pages to bytes after `start + offset*4KB`
 // both table and start must be properly aligned
@@ -73,6 +69,22 @@ void page_free(void* page_start)
     *index = ~(~*index | (1<<(8-(page_number%8))));
 }
 
+// Just pages the entire addressable space. Takes about 4MB of space.
+// Should be ~fine~ this won't break things I totally know what I'm doing
+void page_everything(page_directory_entry* pg_dir)
+{
+    for (int i = 0; i < 1024; i++)
+    {
+        page_table_entry* pg_tab = (page_table_entry*) page_allocate();
+        pg_dir[i] = (page_directory_entry)((uint32_t)pg_tab | PAGE_WRITABLE | PAGE_PRESENT);
+        for (int j = 0; j < 1024; j++)
+        {
+            void* page = (void*)((i << 22) | (j << 12));
+            pg_tab[j] = (page_directory_entry)((uint32_t)page | PAGE_WRITABLE | PAGE_PRESENT);
+        }
+    }
+}
+
 // This goes through all available memory, and maps 1 to 1 virtual memory to it.
 page_directory_entry* mem_init_kern_tables(multiboot_memory_map* mmap, multiboot_memory_map* mmap_end)
 {
@@ -100,8 +112,8 @@ page_directory_entry* mem_init_kern_tables(multiboot_memory_map* mmap, multiboot
             // Lower memory should be first in the page directory and
             // mapped one to one
             populate_page_table(next_table, 0, 1024, 0);
-            page_directory[0] = (uint32_t) next_table;
-            page_directory[0] |= PAGE_WRITABLE | PAGE_PRESENT;
+            kern_page_dir[0] = (uint32_t) next_table;
+            kern_page_dir[0] |= PAGE_WRITABLE | PAGE_PRESENT;
 
             current_dir_entry = 1;
             /* next_table += 0x1000; */
@@ -112,8 +124,8 @@ page_directory_entry* mem_init_kern_tables(multiboot_memory_map* mmap, multiboot
             for (i = 0; i+0x1000000 < mmap->length; i += 0x1000000)
             {
                 populate_page_table(next_table, (void*)(intptr_t) mmap->base_addr + i, 1024 ,0);
-                page_directory[current_dir_entry] = (uint32_t) next_table;
-                page_directory[current_dir_entry] |= PAGE_WRITABLE | PAGE_PRESENT;
+                kern_page_dir[current_dir_entry] = (uint32_t) next_table;
+                kern_page_dir[current_dir_entry] |= PAGE_WRITABLE | PAGE_PRESENT;
 
                 current_dir_entry += 1;
                 /* next_table += 0x1000; */
@@ -123,8 +135,8 @@ page_directory_entry* mem_init_kern_tables(multiboot_memory_map* mmap, multiboot
             if (i != mmap->length)
             {
                 populate_page_table(next_table, (void*)(intptr_t) mmap->base_addr + i, (mmap->length - i) / 0x1000 ,0);
-                page_directory[current_dir_entry] = (uint32_t) next_table;
-                page_directory[current_dir_entry] |= PAGE_WRITABLE | PAGE_PRESENT;
+                kern_page_dir[current_dir_entry] = (uint32_t) next_table;
+                kern_page_dir[current_dir_entry] |= PAGE_WRITABLE | PAGE_PRESENT;
 
                 current_dir_entry += 1;
                 /* next_table += 0x1000; */
@@ -206,15 +218,15 @@ page_directory_entry* initiate_directory()
         //   Write Enabled: It can be both read from and written to
         //     (this is the 2 bit)
         //   Not Present: The page table is not present
-        page_directory[i] = 0;
-        page_directory[i] |= PAGE_WRITABLE;
+        kernel_page_directory[i] = 0;
+        kernel_page_directory[i] |= PAGE_WRITABLE;
     }
 
     // Set last directory entry to point back
-    page_directory[1023] = (uint32_t) page_directory;
-    page_directory[1023] |= PAGE_WRITABLE | PAGE_PRESENT;
+    kernel_page_directory[1023] = (uint32_t) kernel_page_directory;
+    kernel_page_directory[1023] |= PAGE_WRITABLE | PAGE_PRESENT;
 
-    return page_directory;
+    return kernel_page_directory;
 }
 
 void* malloc(uint32_t bytes)
@@ -229,3 +241,21 @@ void* kmalloc(uint32_t size __attribute__((unused)))
 {
     return page_allocate();
 }
+
+
+// Debugging
+void* page_table_inspect(page_directory_entry* pg_dir, void* addr)
+{
+    serial_writestring("Inspecting page tables for address 0x");
+    serial_hexword((uint32_t)addr);
+    serial_writestring("\nDirectory Entry: 0x");
+    page_directory_entry page_dir_entry = pg_dir[((uint32_t)addr) >> 22];
+    serial_hexword(page_dir_entry);
+    serial_writestring("\nPage Table Entry: 0x");
+    page_table_entry* page_table = (page_table_entry*)((uint32_t) page_dir_entry & 0xfffff000);
+    page_table_entry pg_tab_entry = page_table[((uint32_t)addr >> 12) % 1024];
+    serial_hexword(pg_tab_entry);
+    serial_writechar('\n');
+
+    return (void*)((uint32_t)pg_tab_entry & 0xfffff000);
+}

src/mem.h

@@ -27,6 +27,10 @@ typedef uint32_t page_table_entry;
 extern void loadPageDirectory(page_directory_entry*);
 extern void enablePaging();
 
+// page_directory is currently defined once and should not be touched
+// later. It must be page aligned for the MMU to read properly
+page_directory_entry kernel_page_directory[1024] __attribute__((aligned(4096)));
+
 // Defined in linker.ld
 extern char _kernel_end[];
 
@@ -36,6 +40,7 @@ void page_free(void* page_start);
 void* page_map(page_directory_entry pgdir[], void* page_start);
 
 // Initilization
+void page_everything(page_directory_entry* pg_dir);
 page_directory_entry* mem_init_kern_tables(multiboot_memory_map* mmap, multiboot_memory_map* mmap_end);
 
 // Directory and table handling
@@ -51,6 +56,9 @@ void* memory_mark;
 void* kmalloc(uint32_t);
 void* malloc(uint32_t bytes);
 
+// Debugging
+void* page_table_inspect(page_directory_entry* pg_dir, void* addr);
+
 // Required for elf loading - virtual memory and stuff
 
 // TODO: