+#ifdef ENABLE_USER_MODE
+ asm volatile("movw %0, %%ax\n"
+ "movw %%ax, %%es\n"
+ "movw %%ax, %%ds\n"
+ "movw %%ax, %%fs\n"
+ "movw %%ax, %%gs\n"
+ "pushl %0\n"
+ "pushl %1\n"
+ "pushl %2\n"
+ "pushl %3\n"
+ "retf" ::"i"(UDATA_SEG),
+ "i"(USTACK_TOP & ~0xf),
+ "i"(UCODE_SEG),
+ "r"(&&usr));
+#endif
+usr: