fixdep.c 12 KB

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  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. #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. #define INT_CONF ntohl(0x434f4e46)
  117. #define INT_ONFI ntohl(0x4f4e4649)
  118. #define INT_NFIG ntohl(0x4e464947)
  119. #define INT_FIG_ ntohl(0x4649475f)
  120. char *target;
  121. char *depfile;
  122. char *cmdline;
  123. int is_spl_build = 0; /* hack for U-Boot */
  124. static void usage(void)
  125. {
  126. fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");
  127. exit(1);
  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. struct item {
  137. struct item *next;
  138. unsigned int len;
  139. unsigned int hash;
  140. char name[0];
  141. };
  142. #define HASHSZ 256
  143. static struct item *hashtab[HASHSZ];
  144. static unsigned int strhash(const char *str, unsigned int sz)
  145. {
  146. /* fnv32 hash */
  147. unsigned int i, hash = 2166136261U;
  148. for (i = 0; i < sz; i++)
  149. hash = (hash ^ str[i]) * 0x01000193;
  150. return hash;
  151. }
  152. /*
  153. * Lookup a value in the configuration string.
  154. */
  155. static int is_defined_config(const char *name, int len, unsigned int hash)
  156. {
  157. struct item *aux;
  158. for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) {
  159. if (aux->hash == hash && aux->len == len &&
  160. memcmp(aux->name, name, len) == 0)
  161. return 1;
  162. }
  163. return 0;
  164. }
  165. /*
  166. * Add a new value to the configuration string.
  167. */
  168. static void define_config(const char *name, int len, unsigned int hash)
  169. {
  170. struct item *aux = malloc(sizeof(*aux) + len);
  171. if (!aux) {
  172. perror("fixdep:malloc");
  173. exit(1);
  174. }
  175. memcpy(aux->name, name, len);
  176. aux->len = len;
  177. aux->hash = hash;
  178. aux->next = hashtab[hash % HASHSZ];
  179. hashtab[hash % HASHSZ] = aux;
  180. }
  181. /*
  182. * Record the use of a CONFIG_* word.
  183. */
  184. static void use_config(const char *m, int slen)
  185. {
  186. unsigned int hash = strhash(m, slen);
  187. int c, i;
  188. if (is_defined_config(m, slen, hash))
  189. return;
  190. define_config(m, slen, hash);
  191. printf(" $(wildcard include/config/");
  192. for (i = 0; i < slen; i++) {
  193. c = m[i];
  194. if (c == '_')
  195. c = '/';
  196. else
  197. c = tolower(c);
  198. putchar(c);
  199. }
  200. printf(".h) \\\n");
  201. }
  202. static void parse_config_file(const char *map, size_t len)
  203. {
  204. const int *end = (const int *) (map + len);
  205. /* start at +1, so that p can never be < map */
  206. const int *m = (const int *) map + 1;
  207. const char *p, *q;
  208. char tmp_buf[256] = "SPL_"; /* hack for U-Boot */
  209. for (; m < end; m++) {
  210. if (*m == INT_CONF) { p = (char *) m ; goto conf; }
  211. if (*m == INT_ONFI) { p = (char *) m-1; goto conf; }
  212. if (*m == INT_NFIG) { p = (char *) m-2; goto conf; }
  213. if (*m == INT_FIG_) { p = (char *) m-3; goto conf; }
  214. continue;
  215. conf:
  216. if (p > map + len - 7)
  217. continue;
  218. if (memcmp(p, "CONFIG_", 7))
  219. continue;
  220. p += 7;
  221. for (q = p; q < map + len; q++) {
  222. if (!(isalnum(*q) || *q == '_'))
  223. goto found;
  224. }
  225. continue;
  226. found:
  227. if (!memcmp(q - 7, "_MODULE", 7))
  228. q -= 7;
  229. if (q - p < 0)
  230. continue;
  231. /*
  232. * U-Boot also handles
  233. * CONFIG_IS_ENABLED(...)
  234. * CONFIG_IS_BUILTIN(...)
  235. * CONFIG_IS_MODULE(...)
  236. * CONFIG_VAL(...)
  237. */
  238. if ((q - p == 10 && !memcmp(p, "IS_ENABLED(", 11)) ||
  239. (q - p == 10 && !memcmp(p, "IS_BUILTIN(", 11)) ||
  240. (q - p == 9 && !memcmp(p, "IS_MODULE(", 10)) ||
  241. (q - p == 3 && !memcmp(p, "VAL(", 4))) {
  242. p = q + 1;
  243. for (q = p; q < map + len; q++)
  244. if (*q == ')')
  245. goto found2;
  246. continue;
  247. found2:
  248. if (is_spl_build) {
  249. memcpy(tmp_buf + 4, p, q - p);
  250. q = tmp_buf + 4 + (q - p);
  251. p = tmp_buf;
  252. }
  253. }
  254. /* end U-Boot hack */
  255. use_config(p, q - p);
  256. }
  257. }
  258. /* test is s ends in sub */
  259. static int strrcmp(char *s, char *sub)
  260. {
  261. int slen = strlen(s);
  262. int sublen = strlen(sub);
  263. if (sublen > slen)
  264. return 1;
  265. return memcmp(s + slen - sublen, sub, sublen);
  266. }
  267. static void do_config_file(const char *filename)
  268. {
  269. struct stat st;
  270. int fd;
  271. void *map;
  272. fd = open(filename, O_RDONLY);
  273. if (fd < 0) {
  274. fprintf(stderr, "fixdep: error opening config file: ");
  275. perror(filename);
  276. exit(2);
  277. }
  278. if (fstat(fd, &st) < 0) {
  279. fprintf(stderr, "fixdep: error fstat'ing config file: ");
  280. perror(filename);
  281. exit(2);
  282. }
  283. if (st.st_size == 0) {
  284. close(fd);
  285. return;
  286. }
  287. map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
  288. if ((long) map == -1) {
  289. perror("fixdep: mmap");
  290. close(fd);
  291. return;
  292. }
  293. parse_config_file(map, st.st_size);
  294. munmap(map, st.st_size);
  295. close(fd);
  296. }
  297. /*
  298. * Important: The below generated source_foo.o and deps_foo.o variable
  299. * assignments are parsed not only by make, but also by the rather simple
  300. * parser in scripts/mod/sumversion.c.
  301. */
  302. static void parse_dep_file(void *map, size_t len)
  303. {
  304. char *m = map;
  305. char *end = m + len;
  306. char *p;
  307. char s[PATH_MAX];
  308. int is_target;
  309. int saw_any_target = 0;
  310. int is_first_dep = 0;
  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. /* Ignore certain dependencies */
  330. if (strrcmp(s, "include/generated/autoconf.h") &&
  331. strrcmp(s, "arch/um/include/uml-config.h") &&
  332. strrcmp(s, "include/linux/kconfig.h") &&
  333. strrcmp(s, ".ver")) {
  334. /*
  335. * Do not list the source file as dependency,
  336. * so that kbuild is not confused if a .c file
  337. * is rewritten into .S or vice versa. Storing
  338. * it in source_* is needed for modpost to
  339. * compute srcversions.
  340. */
  341. if (is_first_dep) {
  342. /*
  343. * If processing the concatenation of
  344. * multiple dependency files, only
  345. * process the first target name, which
  346. * will be the original source name,
  347. * and ignore any other target names,
  348. * which will be intermediate temporary
  349. * files.
  350. */
  351. if (!saw_any_target) {
  352. saw_any_target = 1;
  353. printf("source_%s := %s\n\n",
  354. target, s);
  355. printf("deps_%s := \\\n",
  356. target);
  357. }
  358. is_first_dep = 0;
  359. } else
  360. printf(" %s \\\n", s);
  361. do_config_file(s);
  362. }
  363. }
  364. /*
  365. * Start searching for next token immediately after the first
  366. * "whitespace" character that follows this token.
  367. */
  368. m = p + 1;
  369. }
  370. if (!saw_any_target) {
  371. fprintf(stderr, "fixdep: parse error; no targets found\n");
  372. exit(1);
  373. }
  374. printf("\n%s: $(deps_%s)\n\n", target, target);
  375. printf("$(deps_%s):\n", target);
  376. }
  377. static void print_deps(void)
  378. {
  379. struct stat st;
  380. int fd;
  381. void *map;
  382. fd = open(depfile, O_RDONLY);
  383. if (fd < 0) {
  384. fprintf(stderr, "fixdep: error opening depfile: ");
  385. perror(depfile);
  386. exit(2);
  387. }
  388. if (fstat(fd, &st) < 0) {
  389. fprintf(stderr, "fixdep: error fstat'ing depfile: ");
  390. perror(depfile);
  391. exit(2);
  392. }
  393. if (st.st_size == 0) {
  394. fprintf(stderr,"fixdep: %s is empty\n",depfile);
  395. close(fd);
  396. return;
  397. }
  398. map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
  399. if ((long) map == -1) {
  400. perror("fixdep: mmap");
  401. close(fd);
  402. return;
  403. }
  404. parse_dep_file(map, st.st_size);
  405. munmap(map, st.st_size);
  406. close(fd);
  407. }
  408. static void traps(void)
  409. {
  410. static char test[] __attribute__((aligned(sizeof(int)))) = "CONF";
  411. int *p = (int *)test;
  412. if (*p != INT_CONF) {
  413. fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianness? %#x\n",
  414. *p);
  415. exit(2);
  416. }
  417. }
  418. int main(int argc, char *argv[])
  419. {
  420. traps();
  421. if (argc != 4)
  422. usage();
  423. depfile = argv[1];
  424. target = argv[2];
  425. cmdline = argv[3];
  426. /* hack for U-Boot */
  427. if (!strncmp(target, "spl/", 4) || !strncmp(target, "tpl/", 4))
  428. is_spl_build = 1;
  429. print_cmdline();
  430. print_deps();
  431. return 0;
  432. }