scripts/basic/fixdep.c

   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         if (fstat(fd, &st) < 0) {
 300                 fprintf(stderr, "fixdep: error fstat'ing config file: ");
 301                 perror(filename);
 302                 exit(2);
 303         }
 304         if (st.st_size == 0) {
 305                 close(fd);
 306                 return;
 307         }
 308         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 309         if ((long) map == -1) {
 310                 perror("fixdep: mmap");
 311                 close(fd);
 312                 return;
 313         }
 314
 315         parse_config_file(map, st.st_size);
 316
 317         munmap(map, st.st_size);
 318
 319         close(fd);
 320 }
 321
 322 /*
 323  * Important: The below generated source_foo.o and deps_foo.o variable
 324  * assignments are parsed not only by make, but also by the rather simple
 325  * parser in scripts/mod/sumversion.c.
 326  */
 327 static void parse_dep_file(void *map, size_t len)
 328 {
 329         char *m = map;
 330         char *end = m + len;
 331         char *p;
 332         char s[PATH_MAX];
 333         int is_target;
 334         int saw_any_target = 0;
 335         int is_first_dep = 0;
 336
 337         while (m < end) {
 338                 /* Skip any "white space" */
 339                 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n'))
 340                         m++;
 341                 /* Find next "white space" */
 342                 p = m;
 343                 while (p < end && *p != ' ' && *p != '\\' && *p != '\n')
 344                         p++;
 345                 /* Is the token we found a target name? */
 346                 is_target = (*(p-1) == ':');
 347                 /* Don't write any target names into the dependency file */
 348                 if (is_target) {
 349                         /* The /next/ file is the first dependency */
 350                         is_first_dep = 1;
 351                 } else {
 352                         /* Save this token/filename */
 353                         memcpy(s, m, p-m);
 354                         s[p - m] = 0;
 355
 356                         /* Ignore certain dependencies */
 357                         if (strrcmp(s, "include/generated/autoconf.h") &&
 358                             strrcmp(s, "arch/um/include/uml-config.h") &&
 359                             strrcmp(s, "include/linux/kconfig.h") &&
 360                             strrcmp(s, ".ver")) {
 361                                 /*
 362                                  * Do not list the source file as dependency,
 363                                  * so that kbuild is not confused if a .c file
 364                                  * is rewritten into .S or vice versa. Storing
 365                                  * it in source_* is needed for modpost to
 366                                  * compute srcversions.
 367                                  */
 368                                 if (is_first_dep) {
 369                                         /*
 370                                          * If processing the concatenation of
 371                                          * multiple dependency files, only
 372                                          * process the first target name, which
 373                                          * will be the original source name,
 374                                          * and ignore any other target names,
 375                                          * which will be intermediate temporary
 376                                          * files.
 377                                          */
 378                                         if (!saw_any_target) {
 379                                                 saw_any_target = 1;
 380                                                 printf("source_%s := %s\n\n",
 381                                                         target, s);
 382                                                 printf("deps_%s := \\\n",
 383                                                         target);
 384                                         }
 385                                         is_first_dep = 0;
 386                                 } else
 387                                         printf("  %s \\\n", s);
 388                                 do_config_file(s);
 389                         }
 390                 }
 391                 /*
 392                  * Start searching for next token immediately after the first
 393                  * "whitespace" character that follows this token.
 394                  */
 395                 m = p + 1;
 396         }
 397
 398         if (!saw_any_target) {
 399                 fprintf(stderr, "fixdep: parse error; no targets found\n");
 400                 exit(1);
 401         }
 402
 403         printf("\n%s: $(deps_%s)\n\n", target, target);
 404         printf("$(deps_%s):\n", target);
 405 }
 406
 407 static void print_deps(void)
 408 {
 409         struct stat st;
 410         int fd;
 411         void *map;
 412
 413         fd = open(depfile, O_RDONLY);
 414         if (fd < 0) {
 415                 fprintf(stderr, "fixdep: error opening depfile: ");
 416                 perror(depfile);
 417                 exit(2);
 418         }
 419         if (fstat(fd, &st) < 0) {
 420                 fprintf(stderr, "fixdep: error fstat'ing depfile: ");
 421                 perror(depfile);
 422                 exit(2);
 423         }
 424         if (st.st_size == 0) {
 425                 fprintf(stderr,"fixdep: %s is empty\n",depfile);
 426                 close(fd);
 427                 return;
 428         }
 429         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 430         if ((long) map == -1) {
 431                 perror("fixdep: mmap");
 432                 close(fd);
 433                 return;
 434         }
 435
 436         parse_dep_file(map, st.st_size);
 437
 438         munmap(map, st.st_size);
 439
 440         close(fd);
 441 }
 442
 443 static void traps(void)
 444 {
 445         static char test[] __attribute__((aligned(sizeof(int)))) = "CONF";
 446         int *p = (int *)test;
 447
 448         if (*p != INT_CONF) {
 449                 fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianness? %#x\n",
 450                         *p);
 451                 exit(2);
 452         }
 453 }
 454
 455 int main(int argc, char *argv[])
 456 {
 457         traps();
 458
 459         if (argc != 4)
 460                 usage();
 461
 462         depfile = argv[1];
 463         target = argv[2];
 464         cmdline = argv[3];
 465
 466         /* hack for U-Boot */
 467         if (!strncmp(target, "spl/", 4) || !strncmp(target, "tpl/", 4))
 468                 is_spl_build = 1;
 469
 470         print_cmdline();
 471         print_deps();
 472
 473         return 0;
 474 }