mm: implement heap with liballoc, might review later

include/kheap.h

@@ -0,0 +1,16 @@
+#ifndef KERNEL_HEAP_H
+#define KERNEL_HEAP_H
+
+#include <stdint.h>
+#include <stddef.h>
+
+#define KHEAP_START  0xE0000000  // Start of kernel heap
+#define KHEAP_INITIAL_SIZE 0x100000 // 1 MiB initial size
+#define KHEAP_END    (KHEAP_START + KHEAP_INITIAL_SIZE)
+#define KHEAP_PAGES  (KHEAP_INITIAL_SIZE / PAGE_SIZE)
+
+void kheap_init();
+void* kvalloc(size_t npages);
+void kvfree(void* addr, size_t npages);
+
+#endif