1// SPDX-License-Identifier: LGPL-2.1-or-later
2/*
3 * Copyright (C) 2005-2006 IBM Corporation.
4 * Author: David Gibson & Adam Litke
5 */
6
7/*\
8 * [Description]
9 *
10 * Tests copy-on-write semantics of large pages where a number of threads
11 * map the same file with the MAP_PRIVATE flag. The threads then write
12 * into their copy of the mapping and recheck the contents to ensure they
13 * were not corrupted by the other threads.
14 */
15
16#include "hugetlb.h"
17
18#define THREADS 5
19#define NR_HUGEPAGES 6
20#define MNTPOINT "hugetlbfs/"
21
22static int fd = -1;
23static long hpage_size;
24
25static void do_work(int thread, size_t size, int fd)
26{
27	char *addr;
28	size_t i;
29	char pattern = thread+65;
30
31	addr = SAFE_MMAP(NULL, size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
32
33	tst_res(TINFO, "Thread %d (pid %d): Mapped at address %p",
34	       thread, getpid(), addr);
35
36	for (i = 0; i < size; i++)
37		memcpy((char *)addr+i, &pattern, 1);
38
39	if (msync(addr, size, MS_SYNC))
40		tst_brk(TBROK | TERRNO, "Thread %d (pid %d): msync() failed",
41				thread, getpid());
42
43	for (i = 0; i < size; i++) {
44		if (addr[i] != pattern) {
45			tst_res(TFAIL, "thread %d (pid: %d): Corruption at %p; "
46				   "Got %c, Expected %c", thread, getpid(),
47				   &addr[i], addr[i], pattern);
48			goto cleanup;
49		}
50	}
51
52	tst_res(TINFO, "Thread %d (pid %d): Pattern verified",
53			thread, getpid());
54
55cleanup:
56	SAFE_MUNMAP(addr, size);
57	exit(0);
58}
59
60static void run_test(void)
61{
62	int i, pid;
63	char *addr;
64	size_t size, itr;
65	pid_t *wait_list;
66
67	wait_list = SAFE_MALLOC(THREADS * sizeof(pid_t));
68	size = (NR_HUGEPAGES / (THREADS+1)) * hpage_size;
69
70	/*
71	 * First, mmap the file with MAP_SHARED and fill with data
72	 * If this is not done, then the fault handler will not be
73	 * called in the kernel since private mappings will be
74	 * created for the children at prefault time.
75	 */
76	addr = SAFE_MMAP(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
77
78	for (itr = 0; itr < size; itr += 8)
79		memcpy(addr+itr, "deadbeef", 8);
80
81	for (i = 0; i < THREADS; i++) {
82		pid = SAFE_FORK();
83
84		if (pid == 0)
85			do_work(i, size, fd);
86
87		wait_list[i] = pid;
88	}
89	tst_reap_children();
90
91	SAFE_MUNMAP(addr, size);
92	free(wait_list);
93	tst_res(TPASS, "mmap COW working as expected.");
94}
95
96static void setup(void)
97{
98	hpage_size = tst_get_hugepage_size();
99	fd = tst_creat_unlinked(MNTPOINT, 0);
100}
101
102static void cleanup(void)
103{
104	if (fd >= 1)
105		SAFE_CLOSE(fd);
106}
107
108static struct tst_test test = {
109	.needs_root = 1,
110	.mntpoint = MNTPOINT,
111	.needs_hugetlbfs = 1,
112	.needs_tmpdir = 1,
113	.forks_child = 1,
114	.setup = setup,
115	.cleanup = cleanup,
116	.test_all = run_test,
117	.hugepages = {NR_HUGEPAGES, TST_NEEDS},
118};
119