1 // SPDX-License-Identifier: GPL-2.0
2
3 /*
4 * Test that MAP_FIXED_NOREPLACE works.
5 *
6 * Copyright 2018, Jann Horn <jannh@google.com>
7 * Copyright 2018, Michael Ellerman, IBM Corporation.
8 */
9
10 #include <sys/mman.h>
11 #include <errno.h>
12 #include <stdio.h>
13 #include <stdlib.h>
14 #include <unistd.h>
15
16 #ifndef MAP_FIXED_NOREPLACE
17 #define MAP_FIXED_NOREPLACE 0x100000
18 #endif
19
20 #define BASE_ADDRESS (256ul * 1024 * 1024)
21
22
dump_maps(void)23 static void dump_maps(void)
24 {
25 char cmd[32];
26
27 snprintf(cmd, sizeof(cmd), "cat /proc/%d/maps", getpid());
28 system(cmd);
29 }
30
main(void)31 int main(void)
32 {
33 unsigned long flags, addr, size, page_size;
34 char *p;
35
36 page_size = sysconf(_SC_PAGE_SIZE);
37
38 flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED_NOREPLACE;
39
40 // Check we can map all the areas we need below
41 errno = 0;
42 addr = BASE_ADDRESS;
43 size = 5 * page_size;
44 p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
45
46 printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
47
48 if (p == MAP_FAILED) {
49 dump_maps();
50 printf("Error: couldn't map the space we need for the test\n");
51 return 1;
52 }
53
54 errno = 0;
55 if (munmap((void *)addr, 5 * page_size) != 0) {
56 dump_maps();
57 printf("Error: munmap failed!?\n");
58 return 1;
59 }
60 printf("unmap() successful\n");
61
62 errno = 0;
63 addr = BASE_ADDRESS + page_size;
64 size = 3 * page_size;
65 p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
66 printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
67
68 if (p == MAP_FAILED) {
69 dump_maps();
70 printf("Error: first mmap() failed unexpectedly\n");
71 return 1;
72 }
73
74 /*
75 * Exact same mapping again:
76 * base | free | new
77 * +1 | mapped | new
78 * +2 | mapped | new
79 * +3 | mapped | new
80 * +4 | free | new
81 */
82 errno = 0;
83 addr = BASE_ADDRESS;
84 size = 5 * page_size;
85 p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
86 printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
87
88 if (p != MAP_FAILED) {
89 dump_maps();
90 printf("Error:1: mmap() succeeded when it shouldn't have\n");
91 return 1;
92 }
93
94 /*
95 * Second mapping contained within first:
96 *
97 * base | free |
98 * +1 | mapped |
99 * +2 | mapped | new
100 * +3 | mapped |
101 * +4 | free |
102 */
103 errno = 0;
104 addr = BASE_ADDRESS + (2 * page_size);
105 size = page_size;
106 p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
107 printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
108
109 if (p != MAP_FAILED) {
110 dump_maps();
111 printf("Error:2: mmap() succeeded when it shouldn't have\n");
112 return 1;
113 }
114
115 /*
116 * Overlap end of existing mapping:
117 * base | free |
118 * +1 | mapped |
119 * +2 | mapped |
120 * +3 | mapped | new
121 * +4 | free | new
122 */
123 errno = 0;
124 addr = BASE_ADDRESS + (3 * page_size);
125 size = 2 * page_size;
126 p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
127 printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
128
129 if (p != MAP_FAILED) {
130 dump_maps();
131 printf("Error:3: mmap() succeeded when it shouldn't have\n");
132 return 1;
133 }
134
135 /*
136 * Overlap start of existing mapping:
137 * base | free | new
138 * +1 | mapped | new
139 * +2 | mapped |
140 * +3 | mapped |
141 * +4 | free |
142 */
143 errno = 0;
144 addr = BASE_ADDRESS;
145 size = 2 * page_size;
146 p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
147 printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
148
149 if (p != MAP_FAILED) {
150 dump_maps();
151 printf("Error:4: mmap() succeeded when it shouldn't have\n");
152 return 1;
153 }
154
155 /*
156 * Adjacent to start of existing mapping:
157 * base | free | new
158 * +1 | mapped |
159 * +2 | mapped |
160 * +3 | mapped |
161 * +4 | free |
162 */
163 errno = 0;
164 addr = BASE_ADDRESS;
165 size = page_size;
166 p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
167 printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
168
169 if (p == MAP_FAILED) {
170 dump_maps();
171 printf("Error:5: mmap() failed when it shouldn't have\n");
172 return 1;
173 }
174
175 /*
176 * Adjacent to end of existing mapping:
177 * base | free |
178 * +1 | mapped |
179 * +2 | mapped |
180 * +3 | mapped |
181 * +4 | free | new
182 */
183 errno = 0;
184 addr = BASE_ADDRESS + (4 * page_size);
185 size = page_size;
186 p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
187 printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
188
189 if (p == MAP_FAILED) {
190 dump_maps();
191 printf("Error:6: mmap() failed when it shouldn't have\n");
192 return 1;
193 }
194
195 addr = BASE_ADDRESS;
196 size = 5 * page_size;
197 if (munmap((void *)addr, size) != 0) {
198 dump_maps();
199 printf("Error: munmap failed!?\n");
200 return 1;
201 }
202 printf("unmap() successful\n");
203
204 printf("OK\n");
205 return 0;
206 }
207
