user: implement mlibc as the libc, finally.

It's finally done..

Signed-off-by: kaguya <vpshinomiya@protonmail.com>

src/mm/vmm.c

@@ -320,4 +320,13 @@ fail:
     spinlock_drop(&pagemap->lock);
     printf("Invalid Phys!\n");
     return INVALID_PHYS;
-}
+}
+
+uintptr_t find_free_vaddr(struct pagemap *pm, size_t len) {
+    // Very naive for now - start from a high address
+    static uintptr_t next = 0x700050000000ULL;
+
+    uintptr_t addr = next;
+    next += ALIGN_UP(len, 0x1000000ULL); // 16 MiB alignment for simplicity
+    return addr;
+}