#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/mman.h>

int main(void) {

	int rc, fd;
	char str[20];
	unsigned long kva;
	void *mmkva;

	fd = open("/proc/xen/xsd_kva", O_RDONLY);
	if (fd == -1) {
		printf("open(/proc/xen/xsd_kva) failed: %s\n", strerror(errno));
		return 1;
	}

	rc = read(fd, str, sizeof(str));
	if (rc == -1) {
		printf("read() failed: %s\n", strerror(errno));
		close(fd);
		return 1;
	}

	close(fd);
	str[rc] = '\0';
	kva = strtoul(str, NULL, 0);
	printf("kva: 0x%lx\n", kva);

	fd = open("/dev/kmem", O_RDWR);
	if (fd == -1) {
		printf("open(/dev/kmem) failed: %s\n", strerror(errno));
		return 1;
	}
	
	mmkva = mmap(NULL, getpagesize(), PROT_READ|PROT_WRITE, MAP_SHARED, fd, kva);
	if (mmkva == MAP_FAILED) {
		printf("mmap() failed: %s\n", strerror(errno));
		close(fd);
		return 1;
	}

	printf("success\n");

	sleep(60);
	munmap(mmkva, getpagesize());
	close(fd);
	return 0;
}