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 <linux/autoconf.h>. 20 * 21 * If the user re-runs make *config, linux/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 linux/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 linux/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 void usage(void) 128 129 { 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 void print_cmdline(void) 138 { 139 printf("cmd_%s := %s\n\n", target, cmdline); 140 } 141 142 char * str_config = NULL; 143 int size_config = 0; 144 int len_config = 0; 145 146 /* 147 * Grow the configuration string to a desired length. 148 * Usually the first growth is plenty. 149 */ 150 void grow_config(int len) 151 { 152 while (len_config + len > size_config) { 153 if (size_config == 0) 154 size_config = 2048; 155 str_config = realloc(str_config, size_config *= 2); 156 if (str_config == NULL) 157 { perror("fixdep:malloc"); exit(1); } 158 } 159 } 160 161 162 163 /* 164 * Lookup a value in the configuration string. 165 */ 166 int is_defined_config(const char * name, int len) 167 { 168 const char * pconfig; 169 const char * plast = str_config + len_config - len; 170 for ( pconfig = str_config + 1; pconfig < plast; pconfig++ ) { 171 if (pconfig[ -1] == '\n' 172 && pconfig[len] == '\n' 173 && !memcmp(pconfig, name, len)) 174 return 1; 175 } 176 return 0; 177 } 178 179 /* 180 * Add a new value to the configuration string. 181 */ 182 void define_config(const char * name, int len) 183 { 184 grow_config(len + 1); 185 186 memcpy(str_config+len_config, name, len); 187 len_config += len; 188 str_config[len_config++] = '\n'; 189 } 190 191 /* 192 * Clear the set of configuration strings. 193 */ 194 void clear_config(void) 195 { 196 len_config = 0; 197 define_config("", 0); 198 } 199 200 /* 201 * Record the use of a CONFIG_* word. 202 */ 203 void use_config(char *m, int slen) 204 { 205 char s[PATH_MAX]; 206 char *p; 207 208 if (is_defined_config(m, slen)) 209 return; 210 211 define_config(m, slen); 212 213 memcpy(s, m, slen); s[slen] = 0; 214 215 for (p = s; p < s + slen; p++) { 216 if (*p == '_') 217 *p = '/'; 218 else 219 *p = tolower((int)*p); 220 } 221 printf(" $(wildcard include/config/%s.h) \\\n", s); 222 } 223 224 void parse_config_file(char *map, size_t len) 225 { 226 int *end = (int *) (map + len); 227 /* start at +1, so that p can never be < map */ 228 int *m = (int *) map + 1; 229 char *p, *q; 230 231 for (; m < end; m++) { 232 if (*m == INT_CONF) { p = (char *) m ; goto conf; } 233 if (*m == INT_ONFI) { p = (char *) m-1; goto conf; } 234 if (*m == INT_NFIG) { p = (char *) m-2; goto conf; } 235 if (*m == INT_FIG_) { p = (char *) m-3; goto conf; } 236 continue; 237 conf: 238 if (p > map + len - 7) 239 continue; 240 if (memcmp(p, "CONFIG_", 7)) 241 continue; 242 for (q = p + 7; q < map + len; q++) { 243 if (!(isalnum(*q) || *q == '_')) 244 goto found; 245 } 246 continue; 247 248 found: 249 if (!memcmp(q - 7, "_MODULE", 7)) 250 q -= 7; 251 if( (q-p-7) < 0 ) 252 continue; 253 use_config(p+7, q-p-7); 254 } 255 } 256 257 /* test is s ends in sub */ 258 int strrcmp(char *s, 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 void do_config_file(char *filename) 270 { 271 struct stat st; 272 int fd; 273 void *map; 274 275 fd = open(filename, O_RDONLY); 276 if (fd < 0) { 277 fprintf(stderr, "fixdep: "); 278 perror(filename); 279 exit(2); 280 } 281 fstat(fd, &st); 282 if (st.st_size == 0) { 283 close(fd); 284 return; 285 } 286 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 287 if ((long) map == -1) { 288 perror("fixdep: mmap"); 289 close(fd); 290 return; 291 } 292 293 parse_config_file(map, st.st_size); 294 295 munmap(map, st.st_size); 296 297 close(fd); 298 } 299 300 void parse_dep_file(void *map, size_t len) 301 { 302 char *m = map; 303 char *end = m + len; 304 char *p; 305 char s[PATH_MAX]; 306 307 p = strchr(m, ':'); 308 if (!p) { 309 fprintf(stderr, "fixdep: parse error\n"); 310 exit(1); 311 } 312 memcpy(s, m, p-m); s[p-m] = 0; 313 printf("deps_%s := \\\n", target); 314 m = p+1; 315 316 clear_config(); 317 318 while (m < end) { 319 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n')) 320 m++; 321 p = m; 322 while (p < end && *p != ' ') p++; 323 if (p == end) { 324 do p--; while (!isalnum(*p)); 325 p++; 326 } 327 memcpy(s, m, p-m); s[p-m] = 0; 328 if (strrcmp(s, "include/linux/autoconf.h") && 329 strrcmp(s, "arch/um/include/uml-config.h") && 330 strrcmp(s, ".ver")) { 331 printf(" %s \\\n", s); 332 do_config_file(s); 333 } 334 m = p + 1; 335 } 336 printf("\n%s: $(deps_%s)\n\n", target, target); 337 printf("$(deps_%s):\n", target); 338 } 339 340 void print_deps(void) 341 { 342 struct stat st; 343 int fd; 344 void *map; 345 346 fd = open(depfile, O_RDONLY); 347 if (fd < 0) { 348 fprintf(stderr, "fixdep: "); 349 perror(depfile); 350 exit(2); 351 } 352 fstat(fd, &st); 353 if (st.st_size == 0) { 354 fprintf(stderr,"fixdep: %s is empty\n",depfile); 355 close(fd); 356 return; 357 } 358 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); 359 if ((long) map == -1) { 360 perror("fixdep: mmap"); 361 close(fd); 362 return; 363 } 364 365 parse_dep_file(map, st.st_size); 366 367 munmap(map, st.st_size); 368 369 close(fd); 370 } 371 372 void traps(void) 373 { 374 static char test[] __attribute__((aligned(sizeof(int)))) = "CONF"; 375 int *p = (int *)test; 376 377 if (*p != INT_CONF) { 378 fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianess? %#x\n", 379 *p); 380 exit(2); 381 } 382 } 383 384 int main(int argc, char *argv[]) 385 { 386 traps(); 387 388 if (argc != 4) 389 usage(); 390 391 depfile = argv[1]; 392 target = argv[2]; 393 cmdline = argv[3]; 394 395 print_cmdline(); 396 print_deps(); 397 398 return 0; 399 } 400