1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (c) 2018 Dmitry Safonov, Arista Networks
4 *
5 * MAP_POPULATE | MAP_PRIVATE should COW VMA pages.
6 */
7
8#define _GNU_SOURCE
9#include <errno.h>
10#include <fcntl.h>
11#include <sys/mman.h>
12#include <sys/socket.h>
13#include <sys/types.h>
14#include <sys/wait.h>
15#include <stdio.h>
16#include <stdlib.h>
17#include <string.h>
18#include <unistd.h>
19#include "../kselftest.h"
20
21#define MMAP_SZ 4096
22
23#define BUG_ON(condition, description) \
24 do { \
25 if (condition) \
26 ksft_exit_fail_msg("[FAIL]\t%s:%d\t%s:%s\n", \
27 __func__, __LINE__, (description), \
28 strerror(errno)); \
29 } while (0)
30
31#define TESTS_IN_CHILD 2
32
33static void parent_f(int sock, unsigned long *smap, int child)
34{
35 int status, ret;
36
37 ret = read(sock, &status, sizeof(int));
38 BUG_ON(ret <= 0, "read(sock)");
39
40 *smap = 0x22222BAD;
41 ret = msync(smap, MMAP_SZ, MS_SYNC);
42 BUG_ON(ret, "msync()");
43
44 ret = write(sock, &status, sizeof(int));
45 BUG_ON(ret <= 0, "write(sock)");
46
47 waitpid(child, &status, 0);
48
49 /* The ksft macros don't keep counters between processes */
50 ksft_cnt.ksft_pass = WEXITSTATUS(status);
51 ksft_cnt.ksft_fail = TESTS_IN_CHILD - WEXITSTATUS(status);
52}
53
54static int child_f(int sock, unsigned long *smap, int fd)
55{
56 int ret, buf = 0;
57
58 smap = mmap(0, MMAP_SZ, PROT_READ | PROT_WRITE,
59 MAP_PRIVATE | MAP_POPULATE, fd, 0);
60 BUG_ON(smap == MAP_FAILED, "mmap()");
61
62 BUG_ON(*smap != 0xdeadbabe, "MAP_PRIVATE | MAP_POPULATE changed file");
63
64 ret = write(sock, &buf, sizeof(int));
65 BUG_ON(ret <= 0, "write(sock)");
66
67 ret = read(sock, &buf, sizeof(int));
68 BUG_ON(ret <= 0, "read(sock)");
69
70 ksft_test_result(*smap != 0x22222BAD, "MAP_POPULATE COW private page\n");
71 ksft_test_result(*smap == 0xdeadbabe, "The mapping state\n");
72
73 /* The ksft macros don't keep counters between processes */
74 return ksft_cnt.ksft_pass;
75}
76
77int main(int argc, char **argv)
78{
79 int sock[2], child, ret;
80 FILE *ftmp;
81 unsigned long *smap;
82
83 ksft_print_header();
84 ksft_set_plan(TESTS_IN_CHILD);
85
86 ftmp = tmpfile();
87 BUG_ON(!ftmp, "tmpfile()");
88
89 ret = ftruncate(fileno(ftmp), MMAP_SZ);
90 BUG_ON(ret, "ftruncate()");
91
92 smap = mmap(0, MMAP_SZ, PROT_READ | PROT_WRITE,
93 MAP_SHARED, fileno(ftmp), 0);
94 BUG_ON(smap == MAP_FAILED, "mmap()");
95
96 *smap = 0xdeadbabe;
97 /* Probably unnecessary, but let it be. */
98 ret = msync(smap, MMAP_SZ, MS_SYNC);
99 BUG_ON(ret, "msync()");
100
101 ret = socketpair(PF_LOCAL, SOCK_SEQPACKET, 0, sock);
102 BUG_ON(ret, "socketpair()");
103
104 child = fork();
105 BUG_ON(child == -1, "fork()");
106
107 if (child) {
108 ret = close(sock[0]);
109 BUG_ON(ret, "close()");
110
111 parent_f(sock: sock[1], smap, child);
112
113 ksft_finished();
114 }
115
116 ret = close(sock[1]);
117 BUG_ON(ret, "close()");
118
119 return child_f(sock: sock[0], smap, fd: fileno(ftmp));
120}
121

source code of linux/tools/testing/selftests/mm/map_populate.c