mm: improve stability by making the page bitmap full by default, also implement liballoc_lock and liballoc_unlock

src/mm/kheap.c

@@ -8,11 +8,13 @@
 
 int liballoc_lock() {
     // Implement locking (disable interrupts or use spinlock)
+    asm volatile("cli");
     return 0;
 }
 
 int liballoc_unlock() {
     // Implement unlocking
+    asm volatile("sti");
     return 0;
 }
 
@@ -81,19 +83,18 @@ void* kvalloc(size_t npages) {
     }
 
     // Temporarily store physical addresses
-    void* phys_addrs[npages];
     uint32_t vaddr = KHEAP_START + start * PAGE_SIZE;
 
-    // Allocate physical pages first
     for (uint32_t i = 0; i < npages; i++) {
-        phys_addrs[i] = alloc_page();
-        if (!phys_addrs[i]) {
-            // Cleanup on failure
-            for (uint32_t j = 0; j < i; j++) {
-                free_page(phys_addrs[j]);
-            }
+        void* phys = alloc_page();
+        if (!phys) {
+            // Out of physical memory! Unmap what we just did and fail.
+            kvfree((void*)vaddr, i); 
             return NULL;
         }
+        
+        // Map the page
+        map_page(phys, (void*)(vaddr + i * PAGE_SIZE), PAGE_PRESENT | PAGE_RW);
     }
 
     // Mark virtual pages as allocated
@@ -101,12 +102,6 @@ void* kvalloc(size_t npages) {
         kheap_bitmap_set(i);
     }
 
-    // Map virtual to physical pages
-    for (uint32_t i = 0; i < npages; i++) {
-        map_page(phys_addrs[i], (void*)(vaddr + i * PAGE_SIZE),
-                 PAGE_PRESENT | PAGE_RW);
-    }
-
     return (void*)vaddr;
 }
 

src/mm/page_alloc.c

@@ -45,7 +45,7 @@ void clear_bit(uint32_t page_index) {
 void init_allocator() {
     int i;
     
-    memset(page_bitmap, 0x00, BITMAP_SIZE);
+    memset(page_bitmap, 0xFF, BITMAP_SIZE);
 }
 
 void* alloc_page() {

src/mm/paging.c

@@ -73,14 +73,14 @@ void grub_memory_map(unsigned int magic, struct multiboot_info* mbi)
         printf("Start Addr: %x | Length: %x | Size: %x | Type: %x\n",
             mmmt->addr_low, mmmt->len_low, mmmt->size, mmmt->type);
 
-        if(mmmt->type != MULTIBOOT_MEMORY_AVAILABLE) {
+        if(mmmt->type == MULTIBOOT_MEMORY_AVAILABLE) {
             /* 
              * Do something with this memory block!
              * BE WARNED that some of memory shown as availiable is actually 
              * actively being used by the kernel! You'll need to take that
              * into account before writing to memory!
              */
-			printf("not available\n");
+			printf("available\n");
             uint32_t size_in_pages = mmmt->len_low / PAGE_SIZE;
             printf("size_in_pages: 0x%X\n", size_in_pages);
 
@@ -88,7 +88,10 @@ void grub_memory_map(unsigned int magic, struct multiboot_info* mbi)
             uint32_t page_count = mmmt->len_low / PAGE_SIZE;
             printf("page_base: %X, page_count: %X\n", base_page, page_count);
 		    for (uint32_t j = 0; j < page_count; j++) {
-                set_bit(base_page + j);
+                // Only clear the bit if it fits in our bitmap
+                if ((base_page + j) < (BITMAP_SIZE * 8)) {
+                    clear_bit(base_page + j);
+                }
             }
         }
     }