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 prerequisites. 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/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 prerequisites. 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 #include <sys/types.h> 98 #include <sys/stat.h> 99 #include <unistd.h> 100 #include <fcntl.h> 101 #include <string.h> 102 #include <stdlib.h> 103 #include <stdio.h> 104 #include <ctype.h> 105 106 static void usage(void) 107 { 108 fprintf(stderr, "Usage: fixdep [-e] <depfile> <target> <cmdline>\n"); 109 fprintf(stderr, " -e insert extra dependencies given on stdin\n"); 110 exit(1); 111 } 112 113 /* 114 * Print out a dependency path from a symbol name 115 */ 116 static void print_config(const char *m, int slen) 117 { 118 int c, i; 119 120 printf(" $(wildcard include/config/"); 121 for (i = 0; i < slen; i++) { 122 c = m[i]; 123 if (c == '_') 124 c = '/'; 125 else 126 c = tolower(c); 127 putchar(c); 128 } 129 printf(".h) \\\n"); 130 } 131 132 static void do_extra_deps(void) 133 { 134 char buf[80]; 135 136 while (fgets(buf, sizeof(buf), stdin)) { 137 int len = strlen(buf); 138 139 if (len < 2 || buf[len - 1] != '\n') { 140 fprintf(stderr, "fixdep: bad data on stdin\n"); 141 exit(1); 142 } 143 print_config(buf, len - 1); 144 } 145 } 146 147 struct item { 148 struct item *next; 149 unsigned int len; 150 unsigned int hash; 151 char name[0]; 152 }; 153 154 #define HASHSZ 256 155 static struct item *hashtab[HASHSZ]; 156 157 static unsigned int strhash(const char *str, unsigned int sz) 158 { 159 /* fnv32 hash */ 160 unsigned int i, hash = 2166136261U; 161 162 for (i = 0; i < sz; i++) 163 hash = (hash ^ str[i]) * 0x01000193; 164 return hash; 165 } 166 167 /* 168 * Lookup a value in the configuration string. 169 */ 170 static int is_defined_config(const char *name, int len, unsigned int hash) 171 { 172 struct item *aux; 173 174 for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) { 175 if (aux->hash == hash && aux->len == len && 176 memcmp(aux->name, name, len) == 0) 177 return 1; 178 } 179 return 0; 180 } 181 182 /* 183 * Add a new value to the configuration string. 184 */ 185 static void define_config(const char *name, int len, unsigned int hash) 186 { 187 struct item *aux = malloc(sizeof(*aux) + len); 188 189 if (!aux) { 190 perror("fixdep:malloc"); 191 exit(1); 192 } 193 memcpy(aux->name, name, len); 194 aux->len = len; 195 aux->hash = hash; 196 aux->next = hashtab[hash % HASHSZ]; 197 hashtab[hash % HASHSZ] = aux; 198 } 199 200 /* 201 * Record the use of a CONFIG_* word. 202 */ 203 static void use_config(const char *m, int slen) 204 { 205 unsigned int hash = strhash(m, slen); 206 207 if (is_defined_config(m, slen, hash)) 208 return; 209 210 define_config(m, slen, hash); 211 print_config(m, slen); 212 } 213 214 /* test if s ends in sub */ 215 static int str_ends_with(const char *s, int slen, const char *sub) 216 { 217 int sublen = strlen(sub); 218 219 if (sublen > slen) 220 return 0; 221 222 return !memcmp(s + slen - sublen, sub, sublen); 223 } 224 225 static void parse_config_file(const char *p) 226 { 227 const char *q, *r; 228 const char *start = p; 229 230 while ((p = strstr(p, "CONFIG_"))) { 231 if (p > start && (isalnum(p[-1]) || p[-1] == '_')) { 232 p += 7; 233 continue; 234 } 235 p += 7; 236 q = p; 237 while (*q && (isalnum(*q) || *q == '_')) 238 q++; 239 if (str_ends_with(p, q - p, "_MODULE")) 240 r = q - 7; 241 else 242 r = q; 243 if (r > p) 244 use_config(p, r - p); 245 p = q; 246 } 247 } 248 249 static void *read_file(const char *filename) 250 { 251 struct stat st; 252 int fd; 253 char *buf; 254 255 fd = open(filename, O_RDONLY); 256 if (fd < 0) { 257 fprintf(stderr, "fixdep: error opening file: "); 258 perror(filename); 259 exit(2); 260 } 261 if (fstat(fd, &st) < 0) { 262 fprintf(stderr, "fixdep: error fstat'ing file: "); 263 perror(filename); 264 exit(2); 265 } 266 buf = malloc(st.st_size + 1); 267 if (!buf) { 268 perror("fixdep: malloc"); 269 exit(2); 270 } 271 if (read(fd, buf, st.st_size) != st.st_size) { 272 perror("fixdep: read"); 273 exit(2); 274 } 275 buf[st.st_size] = '\0'; 276 close(fd); 277 278 return buf; 279 } 280 281 /* Ignore certain dependencies */ 282 static int is_ignored_file(const char *s, int len) 283 { 284 return str_ends_with(s, len, "include/generated/autoconf.h") || 285 str_ends_with(s, len, "include/generated/autoksyms.h") || 286 str_ends_with(s, len, ".ver"); 287 } 288 289 /* 290 * Important: The below generated source_foo.o and deps_foo.o variable 291 * assignments are parsed not only by make, but also by the rather simple 292 * parser in scripts/mod/sumversion.c. 293 */ 294 static void parse_dep_file(char *m, const char *target, int insert_extra_deps) 295 { 296 char *p; 297 int is_last, is_target; 298 int saw_any_target = 0; 299 int is_first_dep = 0; 300 void *buf; 301 302 while (1) { 303 /* Skip any "white space" */ 304 while (*m == ' ' || *m == '\\' || *m == '\n') 305 m++; 306 307 if (!*m) 308 break; 309 310 /* Find next "white space" */ 311 p = m; 312 while (*p && *p != ' ' && *p != '\\' && *p != '\n') 313 p++; 314 is_last = (*p == '\0'); 315 /* Is the token we found a target name? */ 316 is_target = (*(p-1) == ':'); 317 /* Don't write any target names into the dependency file */ 318 if (is_target) { 319 /* The /next/ file is the first dependency */ 320 is_first_dep = 1; 321 } else if (!is_ignored_file(m, p - m)) { 322 *p = '\0'; 323 324 /* 325 * Do not list the source file as dependency, so that 326 * kbuild is not confused if a .c file is rewritten 327 * into .S or vice versa. Storing it in source_* is 328 * needed for modpost to compute srcversions. 329 */ 330 if (is_first_dep) { 331 /* 332 * If processing the concatenation of multiple 333 * dependency files, only process the first 334 * target name, which will be the original 335 * source name, and ignore any other target 336 * names, which will be intermediate temporary 337 * files. 338 */ 339 if (!saw_any_target) { 340 saw_any_target = 1; 341 printf("source_%s := %s\n\n", 342 target, m); 343 printf("deps_%s := \\\n", target); 344 } 345 is_first_dep = 0; 346 } else { 347 printf(" %s \\\n", m); 348 } 349 350 buf = read_file(m); 351 parse_config_file(buf); 352 free(buf); 353 } 354 355 if (is_last) 356 break; 357 358 /* 359 * Start searching for next token immediately after the first 360 * "whitespace" character that follows this token. 361 */ 362 m = p + 1; 363 } 364 365 if (!saw_any_target) { 366 fprintf(stderr, "fixdep: parse error; no targets found\n"); 367 exit(1); 368 } 369 370 if (insert_extra_deps) 371 do_extra_deps(); 372 373 printf("\n%s: $(deps_%s)\n\n", target, target); 374 printf("$(deps_%s):\n", target); 375 } 376 377 int main(int argc, char *argv[]) 378 { 379 const char *depfile, *target, *cmdline; 380 int insert_extra_deps = 0; 381 void *buf; 382 383 if (argc == 5 && !strcmp(argv[1], "-e")) { 384 insert_extra_deps = 1; 385 argv++; 386 } else if (argc != 4) 387 usage(); 388 389 depfile = argv[1]; 390 target = argv[2]; 391 cmdline = argv[3]; 392 393 printf("cmd_%s := %s\n\n", target, cmdline); 394 395 buf = read_file(depfile); 396 parse_dep_file(buf, target, insert_extra_deps); 397 free(buf); 398 399 return 0; 400 } 401