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
22 static int fd = -1;
23 static long hpage_size;
24
do_work(int thread,size_t size,int fd)25 static 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 SAFE_MSYNC(addr, size, MS_SYNC);
40
41 for (i = 0; i < size; i++) {
42 if (addr[i] != pattern) {
43 tst_res(TFAIL, "thread %d (pid: %d): Corruption at %p; "
44 "Got %c, Expected %c", thread, getpid(),
45 &addr[i], addr[i], pattern);
46 goto cleanup;
47 }
48 }
49
50 tst_res(TINFO, "Thread %d (pid %d): Pattern verified",
51 thread, getpid());
52
53 cleanup:
54 SAFE_MUNMAP(addr, size);
55 exit(0);
56 }
57
run_test(void)58 static void run_test(void)
59 {
60 int i, pid;
61 char *addr;
62 size_t size, itr;
63 pid_t *wait_list;
64
65 wait_list = SAFE_MALLOC(THREADS * sizeof(pid_t));
66 size = (NR_HUGEPAGES / (THREADS+1)) * hpage_size;
67
68 /*
69 * First, mmap the file with MAP_SHARED and fill with data
70 * If this is not done, then the fault handler will not be
71 * called in the kernel since private mappings will be
72 * created for the children at prefault time.
73 */
74 addr = SAFE_MMAP(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
75
76 for (itr = 0; itr < size; itr += 8)
77 memcpy(addr+itr, "deadbeef", 8);
78
79 for (i = 0; i < THREADS; i++) {
80 pid = SAFE_FORK();
81
82 if (pid == 0)
83 do_work(i, size, fd);
84
85 wait_list[i] = pid;
86 }
87 tst_reap_children();
88
89 SAFE_MUNMAP(addr, size);
90 free(wait_list);
91 tst_res(TPASS, "mmap COW working as expected.");
92 }
93
setup(void)94 static void setup(void)
95 {
96 hpage_size = tst_get_hugepage_size();
97 fd = tst_creat_unlinked(MNTPOINT, 0);
98 }
99
cleanup(void)100 static void cleanup(void)
101 {
102 if (fd >= 1)
103 SAFE_CLOSE(fd);
104 }
105
106 static struct tst_test test = {
107 .needs_root = 1,
108 .mntpoint = MNTPOINT,
109 .needs_hugetlbfs = 1,
110 .needs_tmpdir = 1,
111 .forks_child = 1,
112 .setup = setup,
113 .cleanup = cleanup,
114 .test_all = run_test,
115 .hugepages = {NR_HUGEPAGES, TST_NEEDS},
116 };
117