/* this program checks cache consistency for a virtually indexed
   direct-mapped cache larger than the page size */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/mman.h>

#define PAGE 8192

main(int argc, char *argv[])
{
  char name[]="/tmp/mapcheckXXXXXX";
  void *area1, *area2;
  long res,res2;
  int fd=mkstemp(name);

  if (fd==-1) {
    fprintf(stderr,"could not open file");
    exit(1);
  }
  unlink(name);
  if (ftruncate(fd,PAGE)) {
    perror("ftruncate");
    exit(1);
  }
  /* map a file */
  if ((area1=mmap(0,PAGE,PROT_READ|PROT_WRITE,MAP_FILE|MAP_SHARED,fd,0))==(void *)-1) {
    perror("map1");
    exit(1);
  }
  /* map same file at an address that differs by an odd number of
     pages, such that it does not map to the same cache entry in a
     two-page cache */
  if ((area2=mmap(area1+3*PAGE,PAGE,PROT_READ|PROT_WRITE,MAP_FILE|MAP_SHARED|MAP_FIXED,fd,0))==(void *)-1) {
    perror("map2");
    exit(1);
  }
  res2=*(long *)area1+*(long *)area2; /* warm up cache */
  *(long *)area1=42; /* write word */
  asm("mb");
  *(long *)area2=23; /* overwrite the same physical word at a
			different virtual address */
  asm("mb");
  res=*(long *)area1; /* read overwritten word from first virtual
			 address */
  printf("area1=0x%lx, area2=0x%lx, Result=%d\n",(long)area1, (long) area2, res);
  if (res==23)
    printf("ok\n");
  else
    printf("cache not consistent\n");
  sprintf(area1,"%d",res2); /* use res2, so the compiler does not
			       optimize it (and the cache warming code) away */
  return 0;
}