Kernel: Handle unaligned ELF segments gracefully in the executable loader.

Kernel/Process.cpp

@@ -338,14 +338,16 @@ int Process::do_exec(String path, Vector<String> arguments, Vector<String> envir
         loader.map_section_hook = [&] (LinearAddress laddr, size_t size, size_t alignment, size_t offset_in_image, bool is_readable, bool is_writable, const String& name) {
             ASSERT(size);
             ASSERT(alignment == PAGE_SIZE);
-            size = ((size / 4096) + 1) * 4096; // FIXME: Use ceil_div?
+            size = ceil_div(size, PAGE_SIZE) * PAGE_SIZE;
             (void) allocate_region_with_vmo(laddr, size, vmo.copy_ref(), offset_in_image, String(name), is_readable, is_writable);
             return laddr.as_ptr();
         };
         loader.alloc_section_hook = [&] (LinearAddress laddr, size_t size, size_t alignment, bool is_readable, bool is_writable, const String& name) {
             ASSERT(size);
             ASSERT(alignment == PAGE_SIZE);
-            size = ((size / 4096) + 1) * 4096; // FIXME: Use ceil_div?
+            size += laddr.get() & 0xfff;
+            laddr.mask(0xffff000);
+            size = ceil_div(size, PAGE_SIZE) * PAGE_SIZE;
             (void) allocate_region(laddr, size, String(name), is_readable, is_writable);
             return laddr.as_ptr();
         };