1// SPDX-License-Identifier: LGPL-2.1-or-later
2/*
3 * Copyright (C) 2013 LG Electronics.
4 * Author: Joonsoo Kim
5 */
6
7/*\
8 * [Description]
9 *
10 * Test to preserve a reserved page against no-reserved mapping. If all
11 * hugepages are reserved, access to no-reserved shared mapping cause a
12 * process die, instead of stealing a hugepage which is reserved for other
13 * process.
14 */
15
16#include <setjmp.h>
17#include "hugetlb.h"
18
19#define MNTPOINT "hugetlbfs/"
20static long hpage_size;
21static int fd1 = -1, fd2 = -1;
22static sigjmp_buf sig_escape;
23static void *sig_expected = MAP_FAILED;
24
25static void sig_handler(int signum, siginfo_t *si, void *uc)
26{
27	(void)uc;
28
29	if (signum == SIGBUS) {
30		if (si->si_addr == sig_expected)
31			siglongjmp(sig_escape, 1);
32		tst_res(TFAIL, "SIGBUS somewhere unexpected: %p (expected: %p)",
33				si->si_addr, sig_expected);
34	} else {
35		tst_res(TFAIL, "Unexpected signal %s", strsignal(signum));
36	}
37}
38
39static int test_write(void *p)
40{
41	volatile char *pl = p;
42
43	if (sigsetjmp(sig_escape, 1)) {
44		/* We got a SIGBUS */
45		return 1;
46	}
47
48	sig_expected = p;
49	barrier();
50	*pl = 's';
51	return 0;
52}
53
54static void run_test(void)
55{
56	int nr_hugepages;
57	int surp_hugepages;
58	int ret;
59	char *p, *q;
60	struct sigaction sa = {
61		.sa_sigaction = sig_handler,
62		.sa_flags = SA_SIGINFO,
63	};
64
65	nr_hugepages = SAFE_READ_MEMINFO(MEMINFO_HPAGE_FREE);
66
67	SAFE_SIGACTION(SIGBUS, &sa, NULL);
68
69	p = SAFE_MMAP(NULL, hpage_size * nr_hugepages,
70		PROT_READ | PROT_WRITE, MAP_SHARED, fd1, 0);
71
72	tst_res(TINFO, "Reserve all hugepages %d", nr_hugepages);
73
74	q = SAFE_MMAP(NULL, hpage_size,
75		PROT_READ | PROT_WRITE, MAP_SHARED | MAP_NORESERVE, fd2, 0);
76
77	tst_res(TINFO, "Write to %p to steal reserved page", q);
78
79	surp_hugepages = SAFE_READ_MEMINFO(MEMINFO_HPAGE_SURP);
80	ret = test_write(q);
81	if (ret == 1) {
82		tst_res(TPASS, "Successful with SIGSEGV received");
83		goto cleanup;
84	}
85
86	/* Provisioning succeeded because of overcommit */
87	if (SAFE_READ_MEMINFO(MEMINFO_HPAGE_SURP) ==
88			surp_hugepages + 1) {
89		tst_res(TPASS, "Successful because of surplus pages");
90		goto cleanup;
91	}
92
93	tst_res(TFAIL, "Steal reserved page");
94cleanup:
95	SAFE_MUNMAP(p, hpage_size * nr_hugepages);
96	SAFE_MUNMAP(q, hpage_size);
97}
98
99static void setup(void)
100{
101	hpage_size = tst_get_hugepage_size();
102	fd1 = tst_creat_unlinked(MNTPOINT, 0);
103	fd2 = tst_creat_unlinked(MNTPOINT, 0);
104}
105
106static void cleanup(void)
107{
108	if (fd1 >= 0)
109		SAFE_CLOSE(fd1);
110	if (fd2 >= 0)
111		SAFE_CLOSE(fd2);
112}
113
114static struct tst_test test = {
115	.needs_root = 1,
116	.mntpoint = MNTPOINT,
117	.needs_hugetlbfs = 1,
118	.needs_tmpdir = 1,
119	.setup = setup,
120	.cleanup = cleanup,
121	.test_all = run_test,
122	.hugepages = {2, TST_NEEDS},
123};
124