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 int is_spl_build = 0; /* hack for U-Boot */ 127 128 static void usage(void) 129 { 130 fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n"); 131 exit(1); 132 } 133 134 /* 135 * Print out the commandline prefixed with cmd_<target filename> := 136 */ 137 static void print_cmdline(void) 138 { 139 printf("cmd_%s := %s\n\n", target, cmdline); 140 } 141 142 struct item { 143 struct item *next; 144 unsigned int len; 145 unsigned int hash; 146 char name[0]; 147 }; 148 149 #define HASHSZ 256 150 static struct item *hashtab[HASHSZ]; 151 152 static unsigned int strhash(const char *str, unsigned int sz) 153 { 154 /* fnv32 hash */ 155 unsigned int i, hash = 2166136261U; 156 157 for (i = 0; i < sz; i++) 158 hash = (hash ^ str[i]) * 0x01000193; 159 return hash; 160 } 161 162 /* 163 * Lookup a value in the configuration string. 164 */ 165 static int is_defined_config(const char *name, int len, unsigned int hash) 166 { 167 struct item *aux; 168 169 for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) { 170 if (aux->hash == hash && aux->len == len && 171 memcmp(aux->name, name, len) == 0) 172 return 1; 173 } 174 return 0; 175 } 176 177 /* 178 * Add a new value to the configuration string. 179 */ 180 static void define_config(const char *name, int len, unsigned int hash) 181 { 182 struct item *aux = malloc(sizeof(*aux) + len); 183 184 if (!aux) { 185 perror("fixdep:malloc"); 186 exit(1); 187 } 188 memcpy(aux->name, name, len); 189 aux->len = len; 190 aux->hash = hash; 191 aux->next = hashtab[hash % HASHSZ]; 192 hashtab[hash % HASHSZ] = aux; 193 } 194 195 /* 196 * Record the use of a CONFIG_* word. 197 */ 198 static void use_config(const char *m, int slen) 199 { 200 unsigned int hash = strhash(m, slen); 201 int c, i; 202 203 if (is_defined_config(m, slen, hash)) 204 return; 205 206 define_config(m, slen, hash); 207 208 printf(" $(wildcard include/config/"); 209 for (i = 0; i < slen; i++) { 210 c = m[i]; 211 if (c == '_') 212 c = '/'; 213 else 214 c = tolower(c); 215 putchar(c); 216 } 217 printf(".h) \\\n"); 218 } 219 220 static void parse_config_file(const char *map, size_t len) 221 { 222 const int *end = (const int *) (map + len); 223 /* start at +1, so that p can never be < map */ 224 const int *m = (const int *) map + 1; 225 const char *p, *q; 226 char tmp_buf[256] = "SPL_"; /* hack for U-Boot */ 227 228 for (; m < end; m++) { 229 if (*m == INT_CONF) { p = (char *) m ; goto conf; } 230 if (*m == INT_ONFI) { p = (char *) m-1; goto conf; } 231 if (*m == INT_NFIG) { p = (char *) m-2; goto conf; } 232 if (*m == INT_FIG_) { p = (char *) m-3; goto conf; } 233 continue; 234 conf: 235 if (p > map + len - 7) 236 continue; 237 if (memcmp(p, "CONFIG_", 7)) 238 continue; 239 p += 7; 240 for (q = p; q < map + len; q++) { 241 if (!(isalnum(*q) || *q == '_')) 242 goto found; 243 } 244 continue; 245 246 found: 247 if (!memcmp(q - 7, "_MODULE", 7)) 248 q -= 7; 249 if (q - p < 0) 250 continue; 251 252 /* U-Boot also handles CONFIG_IS_{ENABLED/BUILTIN/MODULE} */ 253 if ((q - p == 10 && !memcmp(p, "IS_ENABLED(", 11)) || 254 (q - p == 10 && !memcmp(p, "IS_BUILTIN(", 11)) || 255 (q - p == 9 && !memcmp(p, "IS_MODULE(", 10))) { 256 p = q + 1; 257 for (q = p; q < map + len; q++) 258 if (*q == ')') 259 goto found2; 260 continue; 261 262 found2: 263 if (is_spl_build) { 264 memcpy(tmp_buf + 4, p, q - p); 265 q = tmp_buf + 4 + (q - p); 266 p = tmp_buf; 267 } 268 } 269 /* end U-Boot hack */ 270 271 use_config(p, q - p); 272 } 273 } 274 275 /* test is s ends in sub */ 276 static int strrcmp(char *s, char *sub) 277 { 278 int slen = strlen(s); 279 int sublen = strlen(sub); 280 281 if (sublen > slen) 282 return 1; 283 284 return memcmp(s + slen - sublen, sub, sublen); 285 } 286 287 static void do_config_file(const char *filename) 288 { 289 struct stat st; 290 int fd; 291 void *map; 292 293 fd = open(filename, O_RDONLY); 294 if (fd < 0) { 295 fprintf(stderr, "fixdep: error opening config file: "); 296 perror(filename); 297 exit(2); 298 } 299 fstat(fd, &st); 300 if (st.st_size == 0) { 301 close(fd); 302 return; 303 } 304 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 305 if ((long) map == -1) { 306 perror("fixdep: mmap"); 307 close(fd); 308 return; 309 } 310 311 parse_config_file(map, st.st_size); 312 313 munmap(map, st.st_size); 314 315 close(fd); 316 } 317 318 /* 319 * Important: The below generated source_foo.o and deps_foo.o variable 320 * assignments are parsed not only by make, but also by the rather simple 321 * parser in scripts/mod/sumversion.c. 322 */ 323 static void parse_dep_file(void *map, size_t len) 324 { 325 char *m = map; 326 char *end = m + len; 327 char *p; 328 char s[PATH_MAX]; 329 int is_target; 330 int saw_any_target = 0; 331 int is_first_dep = 0; 332 333 while (m < end) { 334 /* Skip any "white space" */ 335 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n')) 336 m++; 337 /* Find next "white space" */ 338 p = m; 339 while (p < end && *p != ' ' && *p != '\\' && *p != '\n') 340 p++; 341 /* Is the token we found a target name? */ 342 is_target = (*(p-1) == ':'); 343 /* Don't write any target names into the dependency file */ 344 if (is_target) { 345 /* The /next/ file is the first dependency */ 346 is_first_dep = 1; 347 } else { 348 /* Save this token/filename */ 349 memcpy(s, m, p-m); 350 s[p - m] = 0; 351 352 /* Ignore certain dependencies */ 353 if (strrcmp(s, "include/generated/autoconf.h") && 354 strrcmp(s, "arch/um/include/uml-config.h") && 355 strrcmp(s, "include/linux/kconfig.h") && 356 strrcmp(s, ".ver")) { 357 /* 358 * Do not list the source file as dependency, 359 * so that kbuild is not confused if a .c file 360 * is rewritten into .S or vice versa. Storing 361 * it in source_* is needed for modpost to 362 * compute srcversions. 363 */ 364 if (is_first_dep) { 365 /* 366 * If processing the concatenation of 367 * multiple dependency files, only 368 * process the first target name, which 369 * will be the original source name, 370 * and ignore any other target names, 371 * which will be intermediate temporary 372 * files. 373 */ 374 if (!saw_any_target) { 375 saw_any_target = 1; 376 printf("source_%s := %s\n\n", 377 target, s); 378 printf("deps_%s := \\\n", 379 target); 380 } 381 is_first_dep = 0; 382 } else 383 printf(" %s \\\n", s); 384 do_config_file(s); 385 } 386 } 387 /* 388 * Start searching for next token immediately after the first 389 * "whitespace" character that follows this token. 390 */ 391 m = p + 1; 392 } 393 394 if (!saw_any_target) { 395 fprintf(stderr, "fixdep: parse error; no targets found\n"); 396 exit(1); 397 } 398 399 printf("\n%s: $(deps_%s)\n\n", target, target); 400 printf("$(deps_%s):\n", target); 401 } 402 403 static void print_deps(void) 404 { 405 struct stat st; 406 int fd; 407 void *map; 408 409 fd = open(depfile, O_RDONLY); 410 if (fd < 0) { 411 fprintf(stderr, "fixdep: error opening depfile: "); 412 perror(depfile); 413 exit(2); 414 } 415 if (fstat(fd, &st) < 0) { 416 fprintf(stderr, "fixdep: error fstat'ing depfile: "); 417 perror(depfile); 418 exit(2); 419 } 420 if (st.st_size == 0) { 421 fprintf(stderr,"fixdep: %s is empty\n",depfile); 422 close(fd); 423 return; 424 } 425 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 426 if ((long) map == -1) { 427 perror("fixdep: mmap"); 428 close(fd); 429 return; 430 } 431 432 parse_dep_file(map, st.st_size); 433 434 munmap(map, st.st_size); 435 436 close(fd); 437 } 438 439 static void traps(void) 440 { 441 static char test[] __attribute__((aligned(sizeof(int)))) = "CONF"; 442 int *p = (int *)test; 443 444 if (*p != INT_CONF) { 445 fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianness? %#x\n", 446 *p); 447 exit(2); 448 } 449 } 450 451 int main(int argc, char *argv[]) 452 { 453 traps(); 454 455 if (argc != 4) 456 usage(); 457 458 depfile = argv[1]; 459 target = argv[2]; 460 cmdline = argv[3]; 461 462 /* hack for U-Boot */ 463 if (!strncmp(target, "spl/", 4) || !strncmp(target, "tpl/", 4)) 464 is_spl_build = 1; 465 466 print_cmdline(); 467 print_deps(); 468 469 return 0; 470 } 471