1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2017 Red Hat, Inc.
4 *
5 */
6
7 /*
8 * Test description: Verify msync() after writing into mmap()-ed file works.
9 *
10 * Write to mapped region and sync the memory back with file. Check the page
11 * is no longer dirty after msync() call.
12 */
13
14 #include <errno.h>
15 #include "tst_test.h"
16 #include "pgsize_helpers.h"
17
18 static int test_fd;
19 static char *mmaped_area;
20 static long pagesize;
21
22 #define STRING_TO_WRITE "AAAAAAAAAA"
23
get_dirty_bit(void * data)24 uint64_t get_dirty_bit(void *data)
25 {
26 int pagemap_fd, pageflags_fd;
27 unsigned long addr;
28 uint64_t pagemap_entry, pageflag_entry, pfn, index;
29
30 addr = (unsigned long)data;
31 index = (addr / kernel_page_size()) * sizeof(uint64_t);
32 pagemap_fd = SAFE_OPEN("/proc/self/pagemap", O_RDONLY);
33 SAFE_LSEEK(pagemap_fd, index, SEEK_SET);
34 SAFE_READ(1, pagemap_fd, &pagemap_entry, sizeof(pagemap_entry));
35 SAFE_CLOSE(pagemap_fd);
36 pfn = pagemap_entry & ((1ULL << 55) - 1);
37 if (!pfn)
38 return 0;
39 pageflags_fd = SAFE_OPEN("/proc/kpageflags", O_RDONLY);
40 index = pfn * sizeof(uint64_t);
41 SAFE_LSEEK(pageflags_fd, index, SEEK_SET);
42 SAFE_READ(1, pageflags_fd, &pageflag_entry, sizeof(pageflag_entry));
43 SAFE_CLOSE(pageflags_fd);
44 return pageflag_entry & (1ULL << 4);
45 }
46
test_msync(void)47 static void test_msync(void)
48 {
49 uint64_t dirty;
50
51 test_fd = SAFE_OPEN("msync04/testfile", O_CREAT | O_TRUNC | O_RDWR,
52 0644);
53 SAFE_WRITE(SAFE_WRITE_ANY, test_fd, STRING_TO_WRITE, sizeof(STRING_TO_WRITE) - 1);
54 mmaped_area = SAFE_MMAP(NULL, pagesize, PROT_READ | PROT_WRITE,
55 MAP_SHARED, test_fd, 0);
56 SAFE_CLOSE(test_fd);
57 mmaped_area[8] = 'B';
58 dirty = get_dirty_bit(mmaped_area);
59 if (!dirty) {
60 tst_res(TFAIL, "Expected dirty bit to be set after writing to"
61 " mmap()-ed area");
62 goto clean;
63 }
64 if (msync(mmaped_area, pagesize, MS_SYNC) < 0) {
65 tst_res(TFAIL | TERRNO, "msync() failed");
66 goto clean;
67 }
68 dirty = get_dirty_bit(mmaped_area);
69 if (dirty)
70 tst_res(TFAIL, "msync() failed to write dirty page despite"
71 " succeeding");
72 else
73 tst_res(TPASS, "msync() working correctly");
74
75 clean:
76 SAFE_MUNMAP(mmaped_area, pagesize);
77 mmaped_area = NULL;
78 }
79
setup(void)80 static void setup(void)
81 {
82 pagesize = (off_t)SAFE_SYSCONF(_SC_PAGESIZE);
83 }
84
cleanup(void)85 static void cleanup(void)
86 {
87 if (mmaped_area)
88 SAFE_MUNMAP(mmaped_area, pagesize);
89
90 if (test_fd > 0)
91 SAFE_CLOSE(test_fd);
92 }
93
94 static struct tst_test test = {
95 .test_all = test_msync,
96 .setup = setup,
97 .cleanup = cleanup,
98 .needs_root = 1,
99 .mntpoint = "msync04",
100 .mount_device = 1,
101 .all_filesystems = 1,
102 .skip_filesystems = (const char *[]) {
103 "tmpfs",
104 NULL
105 },
106 };
107