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 * Record the use of a CONFIG_* word. 196 */ 197 static void use_config(const char *m, int slen) 198 { 199 unsigned int hash = strhash(m, slen); 200 int c, i; 201 202 if (is_defined_config(m, slen, hash)) 203 return; 204 205 define_config(m, slen, hash); 206 207 printf(" $(wildcard include/config/"); 208 for (i = 0; i < slen; i++) { 209 c = m[i]; 210 if (c == '_') 211 c = '/'; 212 else 213 c = tolower(c); 214 putchar(c); 215 } 216 printf(".h) \\\n"); 217 } 218 219 static void parse_config_file(const char *map, size_t len) 220 { 221 const int *end = (const int *) (map + len); 222 /* start at +1, so that p can never be < map */ 223 const int *m = (const int *) map + 1; 224 const char *p, *q; 225 226 for (; m < end; m++) { 227 if (*m == INT_CONF) { p = (char *) m ; goto conf; } 228 if (*m == INT_ONFI) { p = (char *) m-1; goto conf; } 229 if (*m == INT_NFIG) { p = (char *) m-2; goto conf; } 230 if (*m == INT_FIG_) { p = (char *) m-3; goto conf; } 231 continue; 232 conf: 233 if (p > map + len - 7) 234 continue; 235 if (memcmp(p, "CONFIG_", 7)) 236 continue; 237 p += 7; 238 for (q = p; q < map + len; q++) { 239 if (!(isalnum(*q) || *q == '_')) 240 goto found; 241 } 242 continue; 243 244 found: 245 if (!memcmp(q - 7, "_MODULE", 7)) 246 q -= 7; 247 if (q - p < 0) 248 continue; 249 use_config(p, q - p); 250 } 251 } 252 253 /* test is s ends in sub */ 254 static int strrcmp(char *s, char *sub) 255 { 256 int slen = strlen(s); 257 int sublen = strlen(sub); 258 259 if (sublen > slen) 260 return 1; 261 262 return memcmp(s + slen - sublen, sub, sublen); 263 } 264 265 static void do_config_file(const char *filename) 266 { 267 struct stat st; 268 int fd; 269 void *map; 270 271 fd = open(filename, O_RDONLY); 272 if (fd < 0) { 273 fprintf(stderr, "fixdep: error opening config file: "); 274 perror(filename); 275 exit(2); 276 } 277 fstat(fd, &st); 278 if (st.st_size == 0) { 279 close(fd); 280 return; 281 } 282 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 283 if ((long) map == -1) { 284 perror("fixdep: mmap"); 285 close(fd); 286 return; 287 } 288 289 parse_config_file(map, st.st_size); 290 291 munmap(map, st.st_size); 292 293 close(fd); 294 } 295 296 /* 297 * Important: The below generated source_foo.o and deps_foo.o variable 298 * assignments are parsed not only by make, but also by the rather simple 299 * parser in scripts/mod/sumversion.c. 300 */ 301 static void parse_dep_file(void *map, size_t len) 302 { 303 char *m = map; 304 char *end = m + len; 305 char *p; 306 char s[PATH_MAX]; 307 int is_target; 308 int saw_any_target = 0; 309 int is_first_dep = 0; 310 311 while (m < end) { 312 /* Skip any "white space" */ 313 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n')) 314 m++; 315 /* Find next "white space" */ 316 p = m; 317 while (p < end && *p != ' ' && *p != '\\' && *p != '\n') 318 p++; 319 /* Is the token we found a target name? */ 320 is_target = (*(p-1) == ':'); 321 /* Don't write any target names into the dependency file */ 322 if (is_target) { 323 /* The /next/ file is the first dependency */ 324 is_first_dep = 1; 325 } else { 326 /* Save this token/filename */ 327 memcpy(s, m, p-m); 328 s[p - m] = 0; 329 330 /* Ignore certain dependencies */ 331 if (strrcmp(s, "include/generated/autoconf.h") && 332 strrcmp(s, "arch/um/include/uml-config.h") && 333 strrcmp(s, "include/linux/kconfig.h") && 334 strrcmp(s, ".ver")) { 335 /* 336 * Do not list the source file as dependency, 337 * so that kbuild is not confused if a .c file 338 * is rewritten into .S or vice versa. Storing 339 * it in source_* is needed for modpost to 340 * compute srcversions. 341 */ 342 if (is_first_dep) { 343 /* 344 * If processing the concatenation of 345 * multiple dependency files, only 346 * process the first target name, which 347 * will be the original source name, 348 * and ignore any other target names, 349 * which will be intermediate temporary 350 * files. 351 */ 352 if (!saw_any_target) { 353 saw_any_target = 1; 354 printf("source_%s := %s\n\n", 355 target, s); 356 printf("deps_%s := \\\n", 357 target); 358 } 359 is_first_dep = 0; 360 } else 361 printf(" %s \\\n", s); 362 do_config_file(s); 363 } 364 } 365 /* 366 * Start searching for next token immediately after the first 367 * "whitespace" character that follows this token. 368 */ 369 m = p + 1; 370 } 371 372 if (!saw_any_target) { 373 fprintf(stderr, "fixdep: parse error; no targets found\n"); 374 exit(1); 375 } 376 377 printf("\n%s: $(deps_%s)\n\n", target, target); 378 printf("$(deps_%s):\n", target); 379 } 380 381 static void print_deps(void) 382 { 383 struct stat st; 384 int fd; 385 void *map; 386 387 fd = open(depfile, O_RDONLY); 388 if (fd < 0) { 389 fprintf(stderr, "fixdep: error opening depfile: "); 390 perror(depfile); 391 exit(2); 392 } 393 if (fstat(fd, &st) < 0) { 394 fprintf(stderr, "fixdep: error fstat'ing depfile: "); 395 perror(depfile); 396 exit(2); 397 } 398 if (st.st_size == 0) { 399 fprintf(stderr,"fixdep: %s is empty\n",depfile); 400 close(fd); 401 return; 402 } 403 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 404 if ((long) map == -1) { 405 perror("fixdep: mmap"); 406 close(fd); 407 return; 408 } 409 410 parse_dep_file(map, st.st_size); 411 412 munmap(map, st.st_size); 413 414 close(fd); 415 } 416 417 static void traps(void) 418 { 419 static char test[] __attribute__((aligned(sizeof(int)))) = "CONF"; 420 int *p = (int *)test; 421 422 if (*p != INT_CONF) { 423 fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianness? %#x\n", 424 *p); 425 exit(2); 426 } 427 } 428 429 int main(int argc, char *argv[]) 430 { 431 traps(); 432 433 if (argc != 4) 434 usage(); 435 436 depfile = argv[1]; 437 target = argv[2]; 438 cmdline = argv[3]; 439 440 print_cmdline(); 441 print_deps(); 442 443 return 0; 444 } 445