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 * We don't even try to really parse the header files, but 86 * merely grep, i.e. if CONFIG_FOO is mentioned in a comment, it will 87 * be picked up as well. It's not a problem with respect to 88 * correctness, since that can only give too many dependencies, thus 89 * we cannot miss a rebuild. Since people tend to not mention totally 90 * unrelated CONFIG_ options all over the place, it's not an 91 * efficiency problem either. 92 * 93 * (Note: it'd be easy to port over the complete mkdep state machine, 94 * but I don't think the added complexity is worth it) 95 */ 96 /* 97 * Note 2: if somebody writes HELLO_CONFIG_BOOM in a file, it will depend onto 98 * CONFIG_BOOM. This could seem a bug (not too hard to fix), but please do not 99 * fix it! Some UserModeLinux files (look at arch/um/) call CONFIG_BOOM as 100 * UML_CONFIG_BOOM, to avoid conflicts with /usr/include/linux/autoconf.h, 101 * through arch/um/include/uml-config.h; this fixdep "bug" makes sure that 102 * those files will have correct dependencies. 103 */ 104 105 #include <sys/types.h> 106 #include <sys/stat.h> 107 #include <sys/mman.h> 108 #include <unistd.h> 109 #include <fcntl.h> 110 #include <string.h> 111 #include <stdlib.h> 112 #include <stdio.h> 113 #include <limits.h> 114 #include <ctype.h> 115 #include <arpa/inet.h> 116 117 int insert_extra_deps; 118 char *target; 119 char *depfile; 120 char *cmdline; 121 122 static void usage(void) 123 { 124 fprintf(stderr, "Usage: fixdep [-e] <depfile> <target> <cmdline>\n"); 125 fprintf(stderr, " -e insert extra dependencies given on stdin\n"); 126 exit(1); 127 } 128 129 /* 130 * Print out the commandline prefixed with cmd_<target filename> := 131 */ 132 static void print_cmdline(void) 133 { 134 printf("cmd_%s := %s\n\n", target, cmdline); 135 } 136 137 /* 138 * Print out a dependency path from a symbol name 139 */ 140 static void print_config(const char *m, int slen) 141 { 142 int c, i; 143 144 printf(" $(wildcard include/config/"); 145 for (i = 0; i < slen; i++) { 146 c = m[i]; 147 if (c == '_') 148 c = '/'; 149 else 150 c = tolower(c); 151 putchar(c); 152 } 153 printf(".h) \\\n"); 154 } 155 156 static void do_extra_deps(void) 157 { 158 if (insert_extra_deps) { 159 char buf[80]; 160 while(fgets(buf, sizeof(buf), stdin)) { 161 int len = strlen(buf); 162 if (len < 2 || buf[len-1] != '\n') { 163 fprintf(stderr, "fixdep: bad data on stdin\n"); 164 exit(1); 165 } 166 print_config(buf, len-1); 167 } 168 } 169 } 170 171 struct item { 172 struct item *next; 173 unsigned int len; 174 unsigned int hash; 175 char name[0]; 176 }; 177 178 #define HASHSZ 256 179 static struct item *hashtab[HASHSZ]; 180 181 static unsigned int strhash(const char *str, unsigned int sz) 182 { 183 /* fnv32 hash */ 184 unsigned int i, hash = 2166136261U; 185 186 for (i = 0; i < sz; i++) 187 hash = (hash ^ str[i]) * 0x01000193; 188 return hash; 189 } 190 191 /* 192 * Lookup a value in the configuration string. 193 */ 194 static int is_defined_config(const char *name, int len, unsigned int hash) 195 { 196 struct item *aux; 197 198 for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) { 199 if (aux->hash == hash && aux->len == len && 200 memcmp(aux->name, name, len) == 0) 201 return 1; 202 } 203 return 0; 204 } 205 206 /* 207 * Add a new value to the configuration string. 208 */ 209 static void define_config(const char *name, int len, unsigned int hash) 210 { 211 struct item *aux = malloc(sizeof(*aux) + len); 212 213 if (!aux) { 214 perror("fixdep:malloc"); 215 exit(1); 216 } 217 memcpy(aux->name, name, len); 218 aux->len = len; 219 aux->hash = hash; 220 aux->next = hashtab[hash % HASHSZ]; 221 hashtab[hash % HASHSZ] = aux; 222 } 223 224 /* 225 * Record the use of a CONFIG_* word. 226 */ 227 static void use_config(const char *m, int slen) 228 { 229 unsigned int hash = strhash(m, slen); 230 231 if (is_defined_config(m, slen, hash)) 232 return; 233 234 define_config(m, slen, hash); 235 print_config(m, slen); 236 } 237 238 static void parse_config_file(const char *p) 239 { 240 const char *q, *r; 241 242 while ((p = strstr(p, "CONFIG_"))) { 243 p += 7; 244 q = p; 245 while (*q && (isalnum(*q) || *q == '_')) 246 q++; 247 if (memcmp(q - 7, "_MODULE", 7) == 0) 248 r = q - 7; 249 else 250 r = q; 251 if (r > p) 252 use_config(p, r - p); 253 p = q; 254 } 255 } 256 257 /* test if s ends in sub */ 258 static int strrcmp(const char *s, const char *sub) 259 { 260 int slen = strlen(s); 261 int sublen = strlen(sub); 262 263 if (sublen > slen) 264 return 1; 265 266 return memcmp(s + slen - sublen, sub, sublen); 267 } 268 269 static void do_config_file(const char *filename) 270 { 271 struct stat st; 272 int fd; 273 char *map; 274 275 fd = open(filename, O_RDONLY); 276 if (fd < 0) { 277 fprintf(stderr, "fixdep: error opening config file: "); 278 perror(filename); 279 exit(2); 280 } 281 if (fstat(fd, &st) < 0) { 282 fprintf(stderr, "fixdep: error fstat'ing config file: "); 283 perror(filename); 284 exit(2); 285 } 286 if (st.st_size == 0) { 287 close(fd); 288 return; 289 } 290 map = malloc(st.st_size + 1); 291 if (!map) { 292 perror("fixdep: malloc"); 293 close(fd); 294 return; 295 } 296 if (read(fd, map, st.st_size) != st.st_size) { 297 perror("fixdep: read"); 298 close(fd); 299 return; 300 } 301 map[st.st_size] = '\0'; 302 close(fd); 303 304 parse_config_file(map); 305 306 free(map); 307 } 308 309 /* 310 * Important: The below generated source_foo.o and deps_foo.o variable 311 * assignments are parsed not only by make, but also by the rather simple 312 * parser in scripts/mod/sumversion.c. 313 */ 314 static void parse_dep_file(void *map, size_t len) 315 { 316 char *m = map; 317 char *end = m + len; 318 char *p; 319 char s[PATH_MAX]; 320 int is_target; 321 int saw_any_target = 0; 322 int is_first_dep = 0; 323 324 while (m < end) { 325 /* Skip any "white space" */ 326 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n')) 327 m++; 328 /* Find next "white space" */ 329 p = m; 330 while (p < end && *p != ' ' && *p != '\\' && *p != '\n') 331 p++; 332 /* Is the token we found a target name? */ 333 is_target = (*(p-1) == ':'); 334 /* Don't write any target names into the dependency file */ 335 if (is_target) { 336 /* The /next/ file is the first dependency */ 337 is_first_dep = 1; 338 } else { 339 /* Save this token/filename */ 340 memcpy(s, m, p-m); 341 s[p - m] = 0; 342 343 /* Ignore certain dependencies */ 344 if (strrcmp(s, "include/generated/autoconf.h") && 345 strrcmp(s, "include/generated/autoksyms.h") && 346 strrcmp(s, "arch/um/include/uml-config.h") && 347 strrcmp(s, "include/linux/kconfig.h") && 348 strrcmp(s, ".ver")) { 349 /* 350 * Do not list the source file as dependency, 351 * so that kbuild is not confused if a .c file 352 * is rewritten into .S or vice versa. Storing 353 * it in source_* is needed for modpost to 354 * compute srcversions. 355 */ 356 if (is_first_dep) { 357 /* 358 * If processing the concatenation of 359 * multiple dependency files, only 360 * process the first target name, which 361 * will be the original source name, 362 * and ignore any other target names, 363 * which will be intermediate temporary 364 * files. 365 */ 366 if (!saw_any_target) { 367 saw_any_target = 1; 368 printf("source_%s := %s\n\n", 369 target, s); 370 printf("deps_%s := \\\n", 371 target); 372 } 373 is_first_dep = 0; 374 } else 375 printf(" %s \\\n", s); 376 do_config_file(s); 377 } 378 } 379 /* 380 * Start searching for next token immediately after the first 381 * "whitespace" character that follows this token. 382 */ 383 m = p + 1; 384 } 385 386 if (!saw_any_target) { 387 fprintf(stderr, "fixdep: parse error; no targets found\n"); 388 exit(1); 389 } 390 391 do_extra_deps(); 392 393 printf("\n%s: $(deps_%s)\n\n", target, target); 394 printf("$(deps_%s):\n", target); 395 } 396 397 static void print_deps(void) 398 { 399 struct stat st; 400 int fd; 401 void *map; 402 403 fd = open(depfile, O_RDONLY); 404 if (fd < 0) { 405 fprintf(stderr, "fixdep: error opening depfile: "); 406 perror(depfile); 407 exit(2); 408 } 409 if (fstat(fd, &st) < 0) { 410 fprintf(stderr, "fixdep: error fstat'ing depfile: "); 411 perror(depfile); 412 exit(2); 413 } 414 if (st.st_size == 0) { 415 fprintf(stderr,"fixdep: %s is empty\n",depfile); 416 close(fd); 417 return; 418 } 419 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 420 if ((long) map == -1) { 421 perror("fixdep: mmap"); 422 close(fd); 423 return; 424 } 425 426 parse_dep_file(map, st.st_size); 427 428 munmap(map, st.st_size); 429 430 close(fd); 431 } 432 433 int main(int argc, char *argv[]) 434 { 435 if (argc == 5 && !strcmp(argv[1], "-e")) { 436 insert_extra_deps = 1; 437 argv++; 438 } else if (argc != 4) 439 usage(); 440 441 depfile = argv[1]; 442 target = argv[2]; 443 cmdline = argv[3]; 444 445 print_cmdline(); 446 print_deps(); 447 448 return 0; 449 } 450