static void flush_gdt(uint16_t cs, uint16_t ds)
{
    uint64_t scratch0;
    __asm goto(
        "lea %l[lngjmp_target](%%rip), %0\n"
        "push %1\n"
        "push %0\n"
        "ljmpq *(%%rsp)"
    : "=&r"(scratch0)
    : "g"(cs)
    : "rax"
    : lngjmp_target);
    __builtin_unreachable();

lngjmp_target:
    __asm(
        "add $0x10,%%rsp\n"
        "mov %0, %%ds\n"
        "mov %0, %%es\n"
        "mov %0, %%fs\n"
        "mov %0, %%gs\n"
        "mov %0, %%ss\n"
    :
    : "rm"(ds));
}