1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (c) 2019 SUSE LLC
4 * Author: Christian Amann <[email protected]>
5 *
6 * Test userfaultfd
7 *
8 * Force a pagefault event and handle it using userfaultfd
9 * from a different thread
10 */
11
12 #include "config.h"
13 #include "tst_test.h"
14
15 #include <poll.h>
16
17 #include "tst_safe_macros.h"
18 #include "tst_safe_pthread.h"
19 #include "lapi/userfaultfd.h"
20
21 static int page_size;
22 static char *page;
23 static void *copy_page;
24 static int uffd;
25
sys_userfaultfd(int flags)26 static int sys_userfaultfd(int flags)
27 {
28 return tst_syscall(__NR_userfaultfd, flags);
29 }
30
set_pages(void)31 static void set_pages(void)
32 {
33 page_size = sysconf(_SC_PAGE_SIZE);
34 page = SAFE_MMAP(NULL, page_size, PROT_READ | PROT_WRITE,
35 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
36 copy_page = SAFE_MMAP(NULL, page_size, PROT_READ | PROT_WRITE,
37 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
38 }
39
handle_thread(void)40 static void handle_thread(void)
41 {
42 static struct uffd_msg msg;
43 struct uffdio_copy uffdio_copy;
44
45 struct pollfd pollfd;
46 int nready;
47
48 pollfd.fd = uffd;
49 pollfd.events = POLLIN;
50 nready = poll(&pollfd, 1, -1);
51 if (nready == -1)
52 tst_brk(TBROK | TERRNO,
53 "Error on poll");
54
55 SAFE_READ(1, uffd, &msg, sizeof(msg));
56
57 if (msg.event != UFFD_EVENT_PAGEFAULT)
58 tst_brk(TBROK | TERRNO,
59 "Received unexpected UFFD_EVENT");
60
61 memset(copy_page, 'X', page_size);
62
63 uffdio_copy.src = (unsigned long) copy_page;
64
65 uffdio_copy.dst = (unsigned long) msg.arg.pagefault.address
66 & ~(page_size - 1);
67 uffdio_copy.len = page_size;
68 uffdio_copy.mode = 0;
69 uffdio_copy.copy = 0;
70 SAFE_IOCTL(uffd, UFFDIO_COPY, &uffdio_copy);
71
72 close(uffd);
73 }
74
run(void)75 static void run(void)
76 {
77 pthread_t thr;
78 struct uffdio_api uffdio_api;
79 struct uffdio_register uffdio_register;
80
81 set_pages();
82
83 TEST(sys_userfaultfd(O_CLOEXEC | O_NONBLOCK));
84
85 if (TST_RET == -1) {
86 if (TST_ERR == EPERM) {
87 tst_res(TCONF, "Hint: check /proc/sys/vm/unprivileged_userfaultfd");
88 tst_brk(TCONF | TTERRNO,
89 "userfaultfd() requires CAP_SYS_PTRACE on this system");
90 } else
91 tst_brk(TBROK | TTERRNO,
92 "Could not create userfault file descriptor");
93 }
94
95 uffd = TST_RET;
96 uffdio_api.api = UFFD_API;
97 uffdio_api.features = 0;
98 SAFE_IOCTL(uffd, UFFDIO_API, &uffdio_api);
99
100 uffdio_register.range.start = (unsigned long) page;
101 uffdio_register.range.len = page_size;
102 uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
103
104 SAFE_IOCTL(uffd, UFFDIO_REGISTER, &uffdio_register);
105
106 SAFE_PTHREAD_CREATE(&thr, NULL,
107 (void * (*)(void *)) handle_thread, NULL);
108
109 char c = page[0xf];
110
111 if (c == 'X')
112 tst_res(TPASS, "Pagefault handled!");
113 else
114 tst_res(TFAIL, "Pagefault not handled!");
115
116 SAFE_PTHREAD_JOIN(thr, NULL);
117 }
118
119 static struct tst_test test = {
120 .test_all = run,
121 .min_kver = "4.3",
122 };
123