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
17static int test_fd;
18static char *mmaped_area;
19static long pagesize;
20
21#define STRING_TO_WRITE	"AAAAAAAAAA"
22
23uint64_t get_dirty_bit(void *data)
24{
25	int pagemap_fd, pageflags_fd;
26	unsigned long addr;
27	uint64_t pagemap_entry, pageflag_entry, pfn, index;
28
29	addr = (unsigned long)data;
30	index = (addr / pagesize) * sizeof(uint64_t);
31	pagemap_fd = SAFE_OPEN("/proc/self/pagemap", O_RDONLY);
32	SAFE_LSEEK(pagemap_fd, index, SEEK_SET);
33	SAFE_READ(1, pagemap_fd, &pagemap_entry, sizeof(pagemap_entry));
34	SAFE_CLOSE(pagemap_fd);
35	pfn = pagemap_entry & ((1ULL << 55) - 1);
36	if (!pfn)
37		return 0;
38	pageflags_fd = SAFE_OPEN("/proc/kpageflags", O_RDONLY);
39	index = pfn * sizeof(uint64_t);
40	SAFE_LSEEK(pageflags_fd, index, SEEK_SET);
41	SAFE_READ(1, pageflags_fd, &pageflag_entry, sizeof(pageflag_entry));
42	SAFE_CLOSE(pageflags_fd);
43	return pageflag_entry & (1ULL << 4);
44}
45
46static void test_msync(void)
47{
48	uint64_t dirty;
49
50	test_fd = SAFE_OPEN("msync04/testfile", O_CREAT | O_TRUNC | O_RDWR,
51		0644);
52	SAFE_WRITE(SAFE_WRITE_ANY, test_fd, STRING_TO_WRITE, sizeof(STRING_TO_WRITE) - 1);
53	mmaped_area = SAFE_MMAP(NULL, pagesize, PROT_READ | PROT_WRITE,
54			MAP_SHARED, test_fd, 0);
55	SAFE_CLOSE(test_fd);
56	mmaped_area[8] = 'B';
57	dirty = get_dirty_bit(mmaped_area);
58	if (!dirty) {
59		tst_res(TFAIL, "Expected dirty bit to be set after writing to"
60				" mmap()-ed area");
61		goto clean;
62	}
63	if (msync(mmaped_area, pagesize, MS_SYNC) < 0) {
64		tst_res(TFAIL | TERRNO, "msync() failed");
65		goto clean;
66	}
67	dirty = get_dirty_bit(mmaped_area);
68	if (dirty)
69		tst_res(TFAIL, "msync() failed to write dirty page despite"
70				" succeeding");
71	else
72		tst_res(TPASS, "msync() working correctly");
73
74clean:
75	SAFE_MUNMAP(mmaped_area, pagesize);
76	mmaped_area = NULL;
77}
78
79static void setup(void)
80{
81	pagesize = (off_t)SAFE_SYSCONF(_SC_PAGESIZE);
82}
83
84static void cleanup(void)
85{
86	if (mmaped_area)
87		SAFE_MUNMAP(mmaped_area, pagesize);
88
89	if (test_fd > 0)
90		SAFE_CLOSE(test_fd);
91}
92
93static struct tst_test test = {
94	.test_all = test_msync,
95	.setup = setup,
96	.cleanup = cleanup,
97	.needs_root = 1,
98	.mntpoint = "msync04",
99	.mount_device = 1,
100	.all_filesystems = 1,
101	.skip_filesystems = (const char *[]) {
102		"tmpfs",
103		NULL
104	},
105};
106