1 /* 2 * "Optimize" a list of dependencies as spit out by gcc -MD 3 * for the kernel build 4 * =========================================================================== 5 * 6 * Author Kai Germaschewski 7 * Copyright 2002 by Kai Germaschewski <kai.germaschewski@gmx.de> 8 * 9 * This software may be used and distributed according to the terms 10 * of the GNU General Public License, incorporated herein by reference. 11 * 12 * 13 * Introduction: 14 * 15 * gcc produces a very nice and correct list of dependencies which 16 * tells make when to remake a file. 17 * 18 * To use this list as-is however has the drawback that virtually 19 * every file in the kernel includes <linux/config.h> which then again 20 * includes <linux/autoconf.h> 21 * 22 * If the user re-runs make *config, linux/autoconf.h will be 23 * regenerated. make notices that and will rebuild every file which 24 * includes autoconf.h, i.e. basically all files. This is extremely 25 * annoying if the user just changed CONFIG_HIS_DRIVER from n to m. 26 * 27 * So we play the same trick that "mkdep" played before. We replace 28 * the dependency on linux/autoconf.h by a dependency on every config 29 * option which is mentioned in any of the listed prequisites. 30 * 31 * kconfig populates a tree in include/config/ with an empty file 32 * for each config symbol and when the configuration is updated 33 * the files representing changed config options are touched 34 * which then let make pick up the changes and the files that use 35 * the config symbols are rebuilt. 36 * 37 * So if the user changes his CONFIG_HIS_DRIVER option, only the objects 38 * which depend on "include/linux/config/his/driver.h" will be rebuilt, 39 * so most likely only his driver ;-) 40 * 41 * The idea above dates, by the way, back to Michael E Chastain, AFAIK. 42 * 43 * So to get dependencies right, there are two issues: 44 * o if any of the files the compiler read changed, we need to rebuild 45 * o if the command line given to the compile the file changed, we 46 * better rebuild as well. 47 * 48 * The former is handled by using the -MD output, the later by saving 49 * the command line used to compile the old object and comparing it 50 * to the one we would now use. 51 * 52 * Again, also this idea is pretty old and has been discussed on 53 * kbuild-devel a long time ago. I don't have a sensibly working 54 * internet connection right now, so I rather don't mention names 55 * without double checking. 56 * 57 * This code here has been based partially based on mkdep.c, which 58 * says the following about its history: 59 * 60 * Copyright abandoned, Michael Chastain, <mailto:mec@shout.net>. 61 * This is a C version of syncdep.pl by Werner Almesberger. 62 * 63 * 64 * It is invoked as 65 * 66 * fixdep <depfile> <target> <cmdline> 67 * 68 * and will read the dependency file <depfile> 69 * 70 * The transformed dependency snipped is written to stdout. 71 * 72 * It first generates a line 73 * 74 * cmd_<target> = <cmdline> 75 * 76 * and then basically copies the .<target>.d file to stdout, in the 77 * process filtering out the dependency on linux/autoconf.h and adding 78 * dependencies on include/config/my/option.h for every 79 * CONFIG_MY_OPTION encountered in any of the prequisites. 80 * 81 * It will also filter out all the dependencies on *.ver. We need 82 * to make sure that the generated version checksum are globally up 83 * to date before even starting the recursive build, so it's too late 84 * at this point anyway. 85 * 86 * The algorithm to grep for "CONFIG_..." is bit unusual, but should 87 * be fast ;-) We don't even try to really parse the header files, but 88 * merely grep, i.e. if CONFIG_FOO is mentioned in a comment, it will 89 * be picked up as well. It's not a problem with respect to 90 * correctness, since that can only give too many dependencies, thus 91 * we cannot miss a rebuild. Since people tend to not mention totally 92 * unrelated CONFIG_ options all over the place, it's not an 93 * efficiency problem either. 94 * 95 * (Note: it'd be easy to port over the complete mkdep state machine, 96 * but I don't think the added complexity is worth it) 97 */ 98 /* 99 * Note 2: if somebody writes HELLO_CONFIG_BOOM in a file, it will depend onto 100 * CONFIG_BOOM. This could seem a bug (not too hard to fix), but please do not 101 * fix it! Some UserModeLinux files (look at arch/um/) call CONFIG_BOOM as 102 * UML_CONFIG_BOOM, to avoid conflicts with /usr/include/linux/autoconf.h, 103 * through arch/um/include/uml-config.h; this fixdep "bug" makes sure that 104 * those files will have correct dependencies. 105 */ 106 107 #include <sys/types.h> 108 #include <sys/stat.h> 109 #include <sys/mman.h> 110 #include <unistd.h> 111 #include <fcntl.h> 112 #include <string.h> 113 #include <stdlib.h> 114 #include <stdio.h> 115 #include <limits.h> 116 #include <ctype.h> 117 #include <arpa/inet.h> 118 119 #define INT_CONF ntohl(0x434f4e46) 120 #define INT_ONFI ntohl(0x4f4e4649) 121 #define INT_NFIG ntohl(0x4e464947) 122 #define INT_FIG_ ntohl(0x4649475f) 123 124 char *target; 125 char *depfile; 126 char *cmdline; 127 128 void usage(void) 129 130 { 131 fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n"); 132 exit(1); 133 } 134 135 /* 136 * Print out the commandline prefixed with cmd_<target filename> := 137 */ 138 void print_cmdline(void) 139 { 140 printf("cmd_%s := %s\n\n", target, cmdline); 141 } 142 143 char * str_config = NULL; 144 int size_config = 0; 145 int len_config = 0; 146 147 /* 148 * Grow the configuration string to a desired length. 149 * Usually the first growth is plenty. 150 */ 151 void grow_config(int len) 152 { 153 while (len_config + len > size_config) { 154 if (size_config == 0) 155 size_config = 2048; 156 str_config = realloc(str_config, size_config *= 2); 157 if (str_config == NULL) 158 { perror("fixdep:malloc"); exit(1); } 159 } 160 } 161 162 163 164 /* 165 * Lookup a value in the configuration string. 166 */ 167 int is_defined_config(const char * name, int len) 168 { 169 const char * pconfig; 170 const char * plast = str_config + len_config - len; 171 for ( pconfig = str_config + 1; pconfig < plast; pconfig++ ) { 172 if (pconfig[ -1] == '\n' 173 && pconfig[len] == '\n' 174 && !memcmp(pconfig, name, len)) 175 return 1; 176 } 177 return 0; 178 } 179 180 /* 181 * Add a new value to the configuration string. 182 */ 183 void define_config(const char * name, int len) 184 { 185 grow_config(len + 1); 186 187 memcpy(str_config+len_config, name, len); 188 len_config += len; 189 str_config[len_config++] = '\n'; 190 } 191 192 /* 193 * Clear the set of configuration strings. 194 */ 195 void clear_config(void) 196 { 197 len_config = 0; 198 define_config("", 0); 199 } 200 201 /* 202 * Record the use of a CONFIG_* word. 203 */ 204 void use_config(char *m, int slen) 205 { 206 char s[PATH_MAX]; 207 char *p; 208 209 if (is_defined_config(m, slen)) 210 return; 211 212 define_config(m, slen); 213 214 memcpy(s, m, slen); s[slen] = 0; 215 216 for (p = s; p < s + slen; p++) { 217 if (*p == '_') 218 *p = '/'; 219 else 220 *p = tolower((int)*p); 221 } 222 printf(" $(wildcard include/config/%s.h) \\\n", s); 223 } 224 225 void parse_config_file(char *map, size_t len) 226 { 227 int *end = (int *) (map + len); 228 /* start at +1, so that p can never be < map */ 229 int *m = (int *) map + 1; 230 char *p, *q; 231 232 for (; m < end; m++) { 233 if (*m == INT_CONF) { p = (char *) m ; goto conf; } 234 if (*m == INT_ONFI) { p = (char *) m-1; goto conf; } 235 if (*m == INT_NFIG) { p = (char *) m-2; goto conf; } 236 if (*m == INT_FIG_) { p = (char *) m-3; goto conf; } 237 continue; 238 conf: 239 if (p > map + len - 7) 240 continue; 241 if (memcmp(p, "CONFIG_", 7)) 242 continue; 243 for (q = p + 7; q < map + len; q++) { 244 if (!(isalnum(*q) || *q == '_')) 245 goto found; 246 } 247 continue; 248 249 found: 250 if (!memcmp(q - 7, "_MODULE", 7)) 251 q -= 7; 252 use_config(p+7, q-p-7); 253 } 254 } 255 256 /* test is s ends in sub */ 257 int strrcmp(char *s, char *sub) 258 { 259 int slen = strlen(s); 260 int sublen = strlen(sub); 261 262 if (sublen > slen) 263 return 1; 264 265 return memcmp(s + slen - sublen, sub, sublen); 266 } 267 268 void do_config_file(char *filename) 269 { 270 struct stat st; 271 int fd; 272 void *map; 273 274 fd = open(filename, O_RDONLY); 275 if (fd < 0) { 276 fprintf(stderr, "fixdep: "); 277 perror(filename); 278 exit(2); 279 } 280 fstat(fd, &st); 281 if (st.st_size == 0) { 282 close(fd); 283 return; 284 } 285 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 286 if ((long) map == -1) { 287 perror("fixdep: mmap"); 288 close(fd); 289 return; 290 } 291 292 parse_config_file(map, st.st_size); 293 294 munmap(map, st.st_size); 295 296 close(fd); 297 } 298 299 void parse_dep_file(void *map, size_t len) 300 { 301 char *m = map; 302 char *end = m + len; 303 char *p; 304 char s[PATH_MAX]; 305 306 p = strchr(m, ':'); 307 if (!p) { 308 fprintf(stderr, "fixdep: parse error\n"); 309 exit(1); 310 } 311 memcpy(s, m, p-m); s[p-m] = 0; 312 printf("deps_%s := \\\n", target); 313 m = p+1; 314 315 clear_config(); 316 317 while (m < end) { 318 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n')) 319 m++; 320 p = m; 321 while (p < end && *p != ' ') p++; 322 if (p == end) { 323 do p--; while (!isalnum(*p)); 324 p++; 325 } 326 memcpy(s, m, p-m); s[p-m] = 0; 327 if (strrcmp(s, "include/linux/autoconf.h") && 328 strrcmp(s, "arch/um/include/uml-config.h") && 329 strrcmp(s, ".ver")) { 330 printf(" %s \\\n", s); 331 do_config_file(s); 332 } 333 m = p + 1; 334 } 335 printf("\n%s: $(deps_%s)\n\n", target, target); 336 printf("$(deps_%s):\n", target); 337 } 338 339 void print_deps(void) 340 { 341 struct stat st; 342 int fd; 343 void *map; 344 345 fd = open(depfile, O_RDONLY); 346 if (fd < 0) { 347 fprintf(stderr, "fixdep: "); 348 perror(depfile); 349 exit(2); 350 } 351 fstat(fd, &st); 352 if (st.st_size == 0) { 353 fprintf(stderr,"fixdep: %s is empty\n",depfile); 354 close(fd); 355 return; 356 } 357 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 358 if ((long) map == -1) { 359 perror("fixdep: mmap"); 360 close(fd); 361 return; 362 } 363 364 parse_dep_file(map, st.st_size); 365 366 munmap(map, st.st_size); 367 368 close(fd); 369 } 370 371 void traps(void) 372 { 373 static char test[] __attribute__((aligned(sizeof(int)))) = "CONF"; 374 375 if (*(int *)test != INT_CONF) { 376 fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianess? %#x\n", 377 *(int *)test); 378 exit(2); 379 } 380 } 381 382 int main(int argc, char *argv[]) 383 { 384 traps(); 385 386 if (argc != 4) 387 usage(); 388 389 depfile = argv[1]; 390 target = argv[2]; 391 cmdline = argv[3]; 392 393 print_cmdline(); 394 print_deps(); 395 396 return 0; 397 } 398