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 autoconf.h. 20 * 21 * If the user re-runs make *config, autoconf.h will be 22 * regenerated. make notices that and will rebuild every file which 23 * includes autoconf.h, i.e. basically all files. This is extremely 24 * annoying if the user just changed CONFIG_HIS_DRIVER from n to m. 25 * 26 * So we play the same trick that "mkdep" played before. We replace 27 * the dependency on autoconf.h by a dependency on every config 28 * option which is mentioned in any of the listed prequisites. 29 * 30 * kconfig populates a tree in include/config/ with an empty file 31 * for each config symbol and when the configuration is updated 32 * the files representing changed config options are touched 33 * which then let make pick up the changes and the files that use 34 * the config symbols are rebuilt. 35 * 36 * So if the user changes his CONFIG_HIS_DRIVER option, only the objects 37 * which depend on "include/linux/config/his/driver.h" will be rebuilt, 38 * so most likely only his driver ;-) 39 * 40 * The idea above dates, by the way, back to Michael E Chastain, AFAIK. 41 * 42 * So to get dependencies right, there are two issues: 43 * o if any of the files the compiler read changed, we need to rebuild 44 * o if the command line given to the compile the file changed, we 45 * better rebuild as well. 46 * 47 * The former is handled by using the -MD output, the later by saving 48 * the command line used to compile the old object and comparing it 49 * to the one we would now use. 50 * 51 * Again, also this idea is pretty old and has been discussed on 52 * kbuild-devel a long time ago. I don't have a sensibly working 53 * internet connection right now, so I rather don't mention names 54 * without double checking. 55 * 56 * This code here has been based partially based on mkdep.c, which 57 * says the following about its history: 58 * 59 * Copyright abandoned, Michael Chastain, <mailto:mec@shout.net>. 60 * This is a C version of syncdep.pl by Werner Almesberger. 61 * 62 * 63 * It is invoked as 64 * 65 * fixdep <depfile> <target> <cmdline> 66 * 67 * and will read the dependency file <depfile> 68 * 69 * The transformed dependency snipped is written to stdout. 70 * 71 * It first generates a line 72 * 73 * cmd_<target> = <cmdline> 74 * 75 * and then basically copies the .<target>.d file to stdout, in the 76 * process filtering out the dependency on autoconf.h and adding 77 * dependencies on include/config/my/option.h for every 78 * CONFIG_MY_OPTION encountered in any of the prequisites. 79 * 80 * It will also filter out all the dependencies on *.ver. We need 81 * to make sure that the generated version checksum are globally up 82 * to date before even starting the recursive build, so it's too late 83 * at this point anyway. 84 * 85 * The algorithm to grep for "CONFIG_..." is bit unusual, but should 86 * be fast ;-) We don't even try to really parse the header files, but 87 * merely grep, i.e. if CONFIG_FOO is mentioned in a comment, it will 88 * be picked up as well. It's not a problem with respect to 89 * correctness, since that can only give too many dependencies, thus 90 * we cannot miss a rebuild. Since people tend to not mention totally 91 * unrelated CONFIG_ options all over the place, it's not an 92 * efficiency problem either. 93 * 94 * (Note: it'd be easy to port over the complete mkdep state machine, 95 * but I don't think the added complexity is worth it) 96 */ 97 /* 98 * Note 2: if somebody writes HELLO_CONFIG_BOOM in a file, it will depend onto 99 * CONFIG_BOOM. This could seem a bug (not too hard to fix), but please do not 100 * fix it! Some UserModeLinux files (look at arch/um/) call CONFIG_BOOM as 101 * UML_CONFIG_BOOM, to avoid conflicts with /usr/include/linux/autoconf.h, 102 * through arch/um/include/uml-config.h; this fixdep "bug" makes sure that 103 * those files will have correct dependencies. 104 */ 105 106 #include <sys/types.h> 107 #include <sys/stat.h> 108 #include <sys/mman.h> 109 #include <unistd.h> 110 #include <fcntl.h> 111 #include <string.h> 112 #include <stdlib.h> 113 #include <stdio.h> 114 #include <limits.h> 115 #include <ctype.h> 116 #include <arpa/inet.h> 117 118 #define INT_CONF ntohl(0x434f4e46) 119 #define INT_ONFI ntohl(0x4f4e4649) 120 #define INT_NFIG ntohl(0x4e464947) 121 #define INT_FIG_ ntohl(0x4649475f) 122 123 char *target; 124 char *depfile; 125 char *cmdline; 126 127 static void usage(void) 128 { 129 fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n"); 130 exit(1); 131 } 132 133 /* 134 * Print out the commandline prefixed with cmd_<target filename> := 135 */ 136 static void print_cmdline(void) 137 { 138 printf("cmd_%s := %s\n\n", target, cmdline); 139 } 140 141 struct item { 142 struct item *next; 143 unsigned int len; 144 unsigned int hash; 145 char name[0]; 146 }; 147 148 #define HASHSZ 256 149 static struct item *hashtab[HASHSZ]; 150 151 static unsigned int strhash(const char *str, unsigned int sz) 152 { 153 /* fnv32 hash */ 154 unsigned int i, hash = 2166136261U; 155 156 for (i = 0; i < sz; i++) 157 hash = (hash ^ str[i]) * 0x01000193; 158 return hash; 159 } 160 161 /* 162 * Lookup a value in the configuration string. 163 */ 164 static int is_defined_config(const char *name, int len, unsigned int hash) 165 { 166 struct item *aux; 167 168 for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) { 169 if (aux->hash == hash && aux->len == len && 170 memcmp(aux->name, name, len) == 0) 171 return 1; 172 } 173 return 0; 174 } 175 176 /* 177 * Add a new value to the configuration string. 178 */ 179 static void define_config(const char *name, int len, unsigned int hash) 180 { 181 struct item *aux = malloc(sizeof(*aux) + len); 182 183 if (!aux) { 184 perror("fixdep:malloc"); 185 exit(1); 186 } 187 memcpy(aux->name, name, len); 188 aux->len = len; 189 aux->hash = hash; 190 aux->next = hashtab[hash % HASHSZ]; 191 hashtab[hash % HASHSZ] = aux; 192 } 193 194 /* 195 * Clear the set of configuration strings. 196 */ 197 static void clear_config(void) 198 { 199 struct item *aux, *next; 200 unsigned int i; 201 202 for (i = 0; i < HASHSZ; i++) { 203 for (aux = hashtab[i]; aux; aux = next) { 204 next = aux->next; 205 free(aux); 206 } 207 hashtab[i] = NULL; 208 } 209 } 210 211 /* 212 * Record the use of a CONFIG_* word. 213 */ 214 static void use_config(const char *m, int slen) 215 { 216 unsigned int hash = strhash(m, slen); 217 int c, i; 218 219 if (is_defined_config(m, slen, hash)) 220 return; 221 222 define_config(m, slen, hash); 223 224 printf(" $(wildcard include/config/"); 225 for (i = 0; i < slen; i++) { 226 c = m[i]; 227 if (c == '_') 228 c = '/'; 229 else 230 c = tolower(c); 231 putchar(c); 232 } 233 printf(".h) \\\n"); 234 } 235 236 static void parse_config_file(const char *map, size_t len) 237 { 238 const int *end = (const int *) (map + len); 239 /* start at +1, so that p can never be < map */ 240 const int *m = (const int *) map + 1; 241 const char *p, *q; 242 243 for (; m < end; m++) { 244 if (*m == INT_CONF) { p = (char *) m ; goto conf; } 245 if (*m == INT_ONFI) { p = (char *) m-1; goto conf; } 246 if (*m == INT_NFIG) { p = (char *) m-2; goto conf; } 247 if (*m == INT_FIG_) { p = (char *) m-3; goto conf; } 248 continue; 249 conf: 250 if (p > map + len - 7) 251 continue; 252 if (memcmp(p, "CONFIG_", 7)) 253 continue; 254 for (q = p + 7; q < map + len; q++) { 255 if (!(isalnum(*q) || *q == '_')) 256 goto found; 257 } 258 continue; 259 260 found: 261 if (!memcmp(q - 7, "_MODULE", 7)) 262 q -= 7; 263 if( (q-p-7) < 0 ) 264 continue; 265 use_config(p+7, q-p-7); 266 } 267 } 268 269 /* test is s ends in sub */ 270 static int strrcmp(char *s, char *sub) 271 { 272 int slen = strlen(s); 273 int sublen = strlen(sub); 274 275 if (sublen > slen) 276 return 1; 277 278 return memcmp(s + slen - sublen, sub, sublen); 279 } 280 281 static void do_config_file(const char *filename) 282 { 283 struct stat st; 284 int fd; 285 void *map; 286 287 fd = open(filename, O_RDONLY); 288 if (fd < 0) { 289 fprintf(stderr, "fixdep: error opening config file: "); 290 perror(filename); 291 exit(2); 292 } 293 fstat(fd, &st); 294 if (st.st_size == 0) { 295 close(fd); 296 return; 297 } 298 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 299 if ((long) map == -1) { 300 perror("fixdep: mmap"); 301 close(fd); 302 return; 303 } 304 305 parse_config_file(map, st.st_size); 306 307 munmap(map, st.st_size); 308 309 close(fd); 310 } 311 312 /* 313 * Important: The below generated source_foo.o and deps_foo.o variable 314 * assignments are parsed not only by make, but also by the rather simple 315 * parser in scripts/mod/sumversion.c. 316 */ 317 static void parse_dep_file(void *map, size_t len) 318 { 319 char *m = map; 320 char *end = m + len; 321 char *p; 322 char s[PATH_MAX]; 323 int is_target; 324 int saw_any_target = 0; 325 int is_first_dep = 0; 326 327 clear_config(); 328 329 while (m < end) { 330 /* Skip any "white space" */ 331 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n')) 332 m++; 333 /* Find next "white space" */ 334 p = m; 335 while (p < end && *p != ' ' && *p != '\\' && *p != '\n') 336 p++; 337 /* Is the token we found a target name? */ 338 is_target = (*(p-1) == ':'); 339 /* Don't write any target names into the dependency file */ 340 if (is_target) { 341 /* The /next/ file is the first dependency */ 342 is_first_dep = 1; 343 } else { 344 /* Save this token/filename */ 345 memcpy(s, m, p-m); 346 s[p - m] = 0; 347 348 /* Ignore certain dependencies */ 349 if (strrcmp(s, "include/generated/autoconf.h") && 350 strrcmp(s, "arch/um/include/uml-config.h") && 351 strrcmp(s, "include/linux/kconfig.h") && 352 strrcmp(s, ".ver")) { 353 /* 354 * Do not list the source file as dependency, 355 * so that kbuild is not confused if a .c file 356 * is rewritten into .S or vice versa. Storing 357 * it in source_* is needed for modpost to 358 * compute srcversions. 359 */ 360 if (is_first_dep) { 361 /* 362 * If processing the concatenation of 363 * multiple dependency files, only 364 * process the first target name, which 365 * will be the original source name, 366 * and ignore any other target names, 367 * which will be intermediate temporary 368 * files. 369 */ 370 if (!saw_any_target) { 371 saw_any_target = 1; 372 printf("source_%s := %s\n\n", 373 target, s); 374 printf("deps_%s := \\\n", 375 target); 376 } 377 is_first_dep = 0; 378 } else 379 printf(" %s \\\n", s); 380 do_config_file(s); 381 } 382 } 383 /* 384 * Start searching for next token immediately after the first 385 * "whitespace" character that follows this token. 386 */ 387 m = p + 1; 388 } 389 390 if (!saw_any_target) { 391 fprintf(stderr, "fixdep: parse error; no targets found\n"); 392 exit(1); 393 } 394 395 printf("\n%s: $(deps_%s)\n\n", target, target); 396 printf("$(deps_%s):\n", target); 397 } 398 399 static void print_deps(void) 400 { 401 struct stat st; 402 int fd; 403 void *map; 404 405 fd = open(depfile, O_RDONLY); 406 if (fd < 0) { 407 fprintf(stderr, "fixdep: error opening depfile: "); 408 perror(depfile); 409 exit(2); 410 } 411 if (fstat(fd, &st) < 0) { 412 fprintf(stderr, "fixdep: error fstat'ing depfile: "); 413 perror(depfile); 414 exit(2); 415 } 416 if (st.st_size == 0) { 417 fprintf(stderr,"fixdep: %s is empty\n",depfile); 418 close(fd); 419 return; 420 } 421 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 422 if ((long) map == -1) { 423 perror("fixdep: mmap"); 424 close(fd); 425 return; 426 } 427 428 parse_dep_file(map, st.st_size); 429 430 munmap(map, st.st_size); 431 432 close(fd); 433 } 434 435 static void traps(void) 436 { 437 static char test[] __attribute__((aligned(sizeof(int)))) = "CONF"; 438 int *p = (int *)test; 439 440 if (*p != INT_CONF) { 441 fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianness? %#x\n", 442 *p); 443 exit(2); 444 } 445 } 446 447 int main(int argc, char *argv[]) 448 { 449 traps(); 450 451 if (argc != 4) 452 usage(); 453 454 depfile = argv[1]; 455 target = argv[2]; 456 cmdline = argv[3]; 457 458 print_cmdline(); 459 print_deps(); 460 461 return 0; 462 } 463