#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>

int main()
{
	unsigned short ax, cx, dx;
	printf("PID = %d\n", (int)getpid());
	asm volatile ("mov %[one], %%gs\n\t"
		      "1:\n\t"
		      "mov %%gs, %%eax\n\t"
		      "mov %%gs, %%ecx\n\t"
		      "mov %%gs, %%edx\n\t"
		      "cmpw $1, %%ax\n\tjne 2f\n\t"
		      "cmpw $1, %%cx\n\tjne 2f\n\t"
		      "cmpw $1, %%dx\n\tjne 2f\n\t"
		      "jmp 1b\n\t"
		      "2:"
		      : "=a" (ax), "=c" (cx), "=d" (dx)
		      : [one] "rm" ((unsigned short)1));
	printf("ax = %hx, cx = %hx, dx = %hx\n", ax, cx, dx);
	return 0;
}