1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Exercise /dev/mem mmap cases that have been troublesome in the past 4 * 5 * (c) Copyright 2007 Hewlett-Packard Development Company, L.P. 6 * Bjorn Helgaas <bjorn.helgaas@hp.com> 7 */ 8 9 #include <stdlib.h> 10 #include <stdio.h> 11 #include <sys/types.h> 12 #include <dirent.h> 13 #include <fcntl.h> 14 #include <fnmatch.h> 15 #include <string.h> 16 #include <sys/ioctl.h> 17 #include <sys/mman.h> 18 #include <sys/stat.h> 19 #include <unistd.h> 20 #include <linux/pci.h> 21 22 int sum; 23 24 static int map_mem(char *path, off_t offset, size_t length, int touch) 25 { 26 int fd, rc; 27 void *addr; 28 int *c; 29 30 fd = open(path, O_RDWR); 31 if (fd == -1) { 32 perror(path); 33 return -1; 34 } 35 36 if (fnmatch("/proc/bus/pci/*", path, 0) == 0) { 37 rc = ioctl(fd, PCIIOC_MMAP_IS_MEM); 38 if (rc == -1) 39 perror("PCIIOC_MMAP_IS_MEM ioctl"); 40 } 41 42 addr = mmap(NULL, length, PROT_READ|PROT_WRITE, MAP_SHARED, fd, offset); 43 if (addr == MAP_FAILED) 44 return 1; 45 46 if (touch) { 47 c = (int *) addr; 48 while (c < (int *) (addr + length)) 49 sum += *c++; 50 } 51 52 rc = munmap(addr, length); 53 if (rc == -1) { 54 perror("munmap"); 55 return -1; 56 } 57 58 close(fd); 59 return 0; 60 } 61 62 static int scan_tree(char *path, char *file, off_t offset, size_t length, int touch) 63 { 64 struct dirent **namelist; 65 char *name, *path2; 66 int i, n, r, rc = 0, result = 0; 67 struct stat buf; 68 69 n = scandir(path, &namelist, 0, alphasort); 70 if (n < 0) { 71 perror("scandir"); 72 return -1; 73 } 74 75 for (i = 0; i < n; i++) { 76 name = namelist[i]->d_name; 77 78 if (fnmatch(".", name, 0) == 0) 79 goto skip; 80 if (fnmatch("..", name, 0) == 0) 81 goto skip; 82 83 path2 = malloc(strlen(path) + strlen(name) + 3); 84 strcpy(path2, path); 85 strcat(path2, "/"); 86 strcat(path2, name); 87 88 if (fnmatch(file, name, 0) == 0) { 89 rc = map_mem(path2, offset, length, touch); 90 if (rc == 0) 91 fprintf(stderr, "PASS: %s 0x%lx-0x%lx is %s\n", path2, offset, offset + length, touch ? "readable" : "mappable"); 92 else if (rc > 0) 93 fprintf(stderr, "PASS: %s 0x%lx-0x%lx not mappable\n", path2, offset, offset + length); 94 else { 95 fprintf(stderr, "FAIL: %s 0x%lx-0x%lx not accessible\n", path2, offset, offset + length); 96 return rc; 97 } 98 } else { 99 r = lstat(path2, &buf); 100 if (r == 0 && S_ISDIR(buf.st_mode)) { 101 rc = scan_tree(path2, file, offset, length, touch); 102 if (rc < 0) 103 return rc; 104 } 105 } 106 107 result |= rc; 108 free(path2); 109 110 skip: 111 free(namelist[i]); 112 } 113 free(namelist); 114 return result; 115 } 116 117 char buf[1024]; 118 119 static int read_rom(char *path) 120 { 121 int fd, rc; 122 size_t size = 0; 123 124 fd = open(path, O_RDWR); 125 if (fd == -1) { 126 perror(path); 127 return -1; 128 } 129 130 rc = write(fd, "1", 2); 131 if (rc <= 0) { 132 close(fd); 133 perror("write"); 134 return -1; 135 } 136 137 do { 138 rc = read(fd, buf, sizeof(buf)); 139 if (rc > 0) 140 size += rc; 141 } while (rc > 0); 142 143 close(fd); 144 return size; 145 } 146 147 static int scan_rom(char *path, char *file) 148 { 149 struct dirent **namelist; 150 char *name, *path2; 151 int i, n, r, rc = 0, result = 0; 152 struct stat buf; 153 154 n = scandir(path, &namelist, 0, alphasort); 155 if (n < 0) { 156 perror("scandir"); 157 return -1; 158 } 159 160 for (i = 0; i < n; i++) { 161 name = namelist[i]->d_name; 162 163 if (fnmatch(".", name, 0) == 0) 164 goto skip; 165 if (fnmatch("..", name, 0) == 0) 166 goto skip; 167 168 path2 = malloc(strlen(path) + strlen(name) + 3); 169 strcpy(path2, path); 170 strcat(path2, "/"); 171 strcat(path2, name); 172 173 if (fnmatch(file, name, 0) == 0) { 174 rc = read_rom(path2); 175 176 /* 177 * It's OK if the ROM is unreadable. Maybe there 178 * is no ROM, or some other error occurred. The 179 * important thing is that no MCA happened. 180 */ 181 if (rc > 0) 182 fprintf(stderr, "PASS: %s read %d bytes\n", path2, rc); 183 else { 184 fprintf(stderr, "PASS: %s not readable\n", path2); 185 return rc; 186 } 187 } else { 188 r = lstat(path2, &buf); 189 if (r == 0 && S_ISDIR(buf.st_mode)) { 190 rc = scan_rom(path2, file); 191 if (rc < 0) 192 return rc; 193 } 194 } 195 196 result |= rc; 197 free(path2); 198 199 skip: 200 free(namelist[i]); 201 } 202 free(namelist); 203 return result; 204 } 205 206 int main(void) 207 { 208 int rc; 209 210 if (map_mem("/dev/mem", 0, 0xA0000, 1) == 0) 211 fprintf(stderr, "PASS: /dev/mem 0x0-0xa0000 is readable\n"); 212 else 213 fprintf(stderr, "FAIL: /dev/mem 0x0-0xa0000 not accessible\n"); 214 215 /* 216 * It's not safe to blindly read the VGA frame buffer. If you know 217 * how to poke the card the right way, it should respond, but it's 218 * not safe in general. Many machines, e.g., Intel chipsets, cover 219 * up a non-responding card by just returning -1, but others will 220 * report the failure as a machine check. 221 */ 222 if (map_mem("/dev/mem", 0xA0000, 0x20000, 0) == 0) 223 fprintf(stderr, "PASS: /dev/mem 0xa0000-0xc0000 is mappable\n"); 224 else 225 fprintf(stderr, "FAIL: /dev/mem 0xa0000-0xc0000 not accessible\n"); 226 227 if (map_mem("/dev/mem", 0xC0000, 0x40000, 1) == 0) 228 fprintf(stderr, "PASS: /dev/mem 0xc0000-0x100000 is readable\n"); 229 else 230 fprintf(stderr, "FAIL: /dev/mem 0xc0000-0x100000 not accessible\n"); 231 232 /* 233 * Often you can map all the individual pieces above (0-0xA0000, 234 * 0xA0000-0xC0000, and 0xC0000-0x100000), but can't map the whole 235 * thing at once. This is because the individual pieces use different 236 * attributes, and there's no single attribute supported over the 237 * whole region. 238 */ 239 rc = map_mem("/dev/mem", 0, 1024*1024, 0); 240 if (rc == 0) 241 fprintf(stderr, "PASS: /dev/mem 0x0-0x100000 is mappable\n"); 242 else if (rc > 0) 243 fprintf(stderr, "PASS: /dev/mem 0x0-0x100000 not mappable\n"); 244 else 245 fprintf(stderr, "FAIL: /dev/mem 0x0-0x100000 not accessible\n"); 246 247 scan_tree("/sys/class/pci_bus", "legacy_mem", 0, 0xA0000, 1); 248 scan_tree("/sys/class/pci_bus", "legacy_mem", 0xA0000, 0x20000, 0); 249 scan_tree("/sys/class/pci_bus", "legacy_mem", 0xC0000, 0x40000, 1); 250 scan_tree("/sys/class/pci_bus", "legacy_mem", 0, 1024*1024, 0); 251 252 scan_rom("/sys/devices", "rom"); 253 254 scan_tree("/proc/bus/pci", "??.?", 0, 0xA0000, 1); 255 scan_tree("/proc/bus/pci", "??.?", 0xA0000, 0x20000, 0); 256 scan_tree("/proc/bus/pci", "??.?", 0xC0000, 0x40000, 1); 257 scan_tree("/proc/bus/pci", "??.?", 0, 1024*1024, 0); 258 259 return rc; 260 } 261