Espresso 0.0.2c

lib/mm/pmm.c

@@ -12,6 +12,10 @@ static size_t total_pages;
 #define BITMAP_CLEAR(i) (bitmap[(i) / 8] &= ~(1 << ((i) % 8)))
 #define BITMAP_TEST(i)  (bitmap[(i) / 8] &   (1 << ((i) % 8)))
 
+
+extern uint32_t __kernel_start;
+extern uint32_t __kernel_end;
+
 void pmm_init(multiboot_info_t* mb)
 {
 #ifdef _DEBUG
@@ -45,6 +49,18 @@ void pmm_init(multiboot_info_t* mb)
     }
   }
   total_pages = MAX_PAGES;
+
+  uintptr_t start = (uintptr_t)&__kernel_start;
+  uintptr_t end   = (uintptr_t)&__kernel_end;
+
+  start &= ~0xFFF;
+  end = (end + 0xFFF) & ~0xFFF;
+
+  for (uintptr_t addr = start; addr < end; addr += 0x1000)
+  {
+    size_t idx = addr / 0x1000;
+    BITMAP_SET(idx);   // Mark kernel pages as USED
+  }
   
 #ifdef _DEBUG
   printf("[ PMM ] Physical memory manager initialized\n");
@@ -55,6 +71,14 @@ void* pmm_alloc_page(void)
 {
   for (uint32_t i = 0; i < total_pages; ++i)
   {
+    void* page = (void*)(i * 4096);
+
+    if ((uintptr_t)page >= (uintptr_t)&__kernel_start &&
+        (uintptr_t)page <  (uintptr_t)&__kernel_end)
+    {
+      printf("PMM allocating inside kernel at %x\n", page);
+    }
+    
     if (!BITMAP_TEST(i))
     {
       BITMAP_SET(i);