1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
|
/* $OpenBSD: mmaptest.c,v 1.6 2003/07/31 21:48:08 deraadt Exp $ */
/*
* Written by Artur Grabowski <art@openbsd.org>, 2001 Public Domain
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <err.h>
#include <string.h>
#include <sys/types.h>
#include <sys/mman.h>
/*
* Map the same physical page in two places in memory.
* Should cause a cache alias on sparc and other VAC architectures.
*/
#define MAGIC "The voices in my head are trying to ignore me."
int
main(int argc, char *argv[])
{
char fname[25] = "/tmp/mmaptestXXXXXXXXXX";
int page_size;
int fd;
char *v1, *v2;
if ((fd = mkstemp(fname)) < 0)
err(1, "mkstemp");
if (remove(fname) < 0)
err(1, "remove");
if ((page_size = sysconf(_SC_PAGESIZE)) < 0)
err(1, "sysconf");
if (ftruncate(fd, 2 * page_size) < 0)
err(1, "ftruncate");
/* map two pages, then map the first page over the second */
v1 = mmap(NULL, 2 * page_size, PROT_READ|PROT_WRITE,
MAP_SHARED, fd, 0);
if (v1 == MAP_FAILED)
err(1, "mmap 1");
/* No need to unmap, mmap is supposed to do that for us if MAP_FIXED */
v2 = mmap(v1 + page_size, page_size, PROT_READ|PROT_WRITE,
MAP_SHARED|MAP_FIXED, fd, 0);
if (v2 == MAP_FAILED)
err(1, "mmap 2");
memcpy(v1, MAGIC, sizeof(MAGIC));
if (memcmp(v2, MAGIC, sizeof(MAGIC)) != 0)
errx(1, "comparison 1 failed");
if (memcmp(v1, v2, sizeof(MAGIC)) != 0)
errx(1, "comparison 2 failed");
if (munmap(v1, 2 * page_size) < 0)
errx(1, "munmap");
close(fd);
return 0;
}
|
