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_dep(const char *m, int slen, const char *dir) 117 { 118 int c, prev_c = '/', i; 119 120 printf(" $(wildcard %s/", dir); 121 for (i = 0; i < slen; i++) { 122 c = m[i]; 123 if (c == '_') 124 c = '/'; 125 else 126 c = tolower(c); 127 if (c != '/' || prev_c != '/') 128 putchar(c); 129 prev_c = c; 130 } 131 printf(".h) \\\n"); 132 } 133 134 static void do_extra_deps(void) 135 { 136 char buf[80]; 137 138 while (fgets(buf, sizeof(buf), stdin)) { 139 int len = strlen(buf); 140 141 if (len < 2 || buf[len - 1] != '\n') { 142 fprintf(stderr, "fixdep: bad data on stdin\n"); 143 exit(1); 144 } 145 print_dep(buf, len - 1, "include/ksym"); 146 } 147 } 148 149 struct item { 150 struct item *next; 151 unsigned int len; 152 unsigned int hash; 153 char name[0]; 154 }; 155 156 #define HASHSZ 256 157 static struct item *hashtab[HASHSZ]; 158 159 static unsigned int strhash(const char *str, unsigned int sz) 160 { 161 /* fnv32 hash */ 162 unsigned int i, hash = 2166136261U; 163 164 for (i = 0; i < sz; i++) 165 hash = (hash ^ str[i]) * 0x01000193; 166 return hash; 167 } 168 169 /* 170 * Lookup a value in the configuration string. 171 */ 172 static int is_defined_config(const char *name, int len, unsigned int hash) 173 { 174 struct item *aux; 175 176 for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) { 177 if (aux->hash == hash && aux->len == len && 178 memcmp(aux->name, name, len) == 0) 179 return 1; 180 } 181 return 0; 182 } 183 184 /* 185 * Add a new value to the configuration string. 186 */ 187 static void define_config(const char *name, int len, unsigned int hash) 188 { 189 struct item *aux = malloc(sizeof(*aux) + len); 190 191 if (!aux) { 192 perror("fixdep:malloc"); 193 exit(1); 194 } 195 memcpy(aux->name, name, len); 196 aux->len = len; 197 aux->hash = hash; 198 aux->next = hashtab[hash % HASHSZ]; 199 hashtab[hash % HASHSZ] = aux; 200 } 201 202 /* 203 * Record the use of a CONFIG_* word. 204 */ 205 static void use_config(const char *m, int slen) 206 { 207 unsigned int hash = strhash(m, slen); 208 209 if (is_defined_config(m, slen, hash)) 210 return; 211 212 define_config(m, slen, hash); 213 print_dep(m, slen, "include/config"); 214 } 215 216 /* test if s ends in sub */ 217 static int str_ends_with(const char *s, int slen, const char *sub) 218 { 219 int sublen = strlen(sub); 220 221 if (sublen > slen) 222 return 0; 223 224 return !memcmp(s + slen - sublen, sub, sublen); 225 } 226 227 static void parse_config_file(const char *p) 228 { 229 const char *q, *r; 230 const char *start = p; 231 232 while ((p = strstr(p, "CONFIG_"))) { 233 if (p > start && (isalnum(p[-1]) || p[-1] == '_')) { 234 p += 7; 235 continue; 236 } 237 p += 7; 238 q = p; 239 while (*q && (isalnum(*q) || *q == '_')) 240 q++; 241 if (str_ends_with(p, q - p, "_MODULE")) 242 r = q - 7; 243 else 244 r = q; 245 if (r > p) 246 use_config(p, r - p); 247 p = q; 248 } 249 } 250 251 static void *read_file(const char *filename) 252 { 253 struct stat st; 254 int fd; 255 char *buf; 256 257 fd = open(filename, O_RDONLY); 258 if (fd < 0) { 259 fprintf(stderr, "fixdep: error opening file: "); 260 perror(filename); 261 exit(2); 262 } 263 if (fstat(fd, &st) < 0) { 264 fprintf(stderr, "fixdep: error fstat'ing file: "); 265 perror(filename); 266 exit(2); 267 } 268 buf = malloc(st.st_size + 1); 269 if (!buf) { 270 perror("fixdep: malloc"); 271 exit(2); 272 } 273 if (read(fd, buf, st.st_size) != st.st_size) { 274 perror("fixdep: read"); 275 exit(2); 276 } 277 buf[st.st_size] = '\0'; 278 close(fd); 279 280 return buf; 281 } 282 283 /* Ignore certain dependencies */ 284 static int is_ignored_file(const char *s, int len) 285 { 286 return str_ends_with(s, len, "include/generated/autoconf.h") || 287 str_ends_with(s, len, "include/generated/autoksyms.h") || 288 str_ends_with(s, len, ".ver"); 289 } 290 291 /* 292 * Important: The below generated source_foo.o and deps_foo.o variable 293 * assignments are parsed not only by make, but also by the rather simple 294 * parser in scripts/mod/sumversion.c. 295 */ 296 static void parse_dep_file(char *m, const char *target, int insert_extra_deps) 297 { 298 char *p; 299 int is_last, is_target; 300 int saw_any_target = 0; 301 int is_first_dep = 0; 302 void *buf; 303 304 while (1) { 305 /* Skip any "white space" */ 306 while (*m == ' ' || *m == '\\' || *m == '\n') 307 m++; 308 309 if (!*m) 310 break; 311 312 /* Find next "white space" */ 313 p = m; 314 while (*p && *p != ' ' && *p != '\\' && *p != '\n') 315 p++; 316 is_last = (*p == '\0'); 317 /* Is the token we found a target name? */ 318 is_target = (*(p-1) == ':'); 319 /* Don't write any target names into the dependency file */ 320 if (is_target) { 321 /* The /next/ file is the first dependency */ 322 is_first_dep = 1; 323 } else if (!is_ignored_file(m, p - m)) { 324 *p = '\0'; 325 326 /* 327 * Do not list the source file as dependency, so that 328 * kbuild is not confused if a .c file is rewritten 329 * into .S or vice versa. Storing it in source_* is 330 * needed for modpost to compute srcversions. 331 */ 332 if (is_first_dep) { 333 /* 334 * If processing the concatenation of multiple 335 * dependency files, only process the first 336 * target name, which will be the original 337 * source name, and ignore any other target 338 * names, which will be intermediate temporary 339 * files. 340 */ 341 if (!saw_any_target) { 342 saw_any_target = 1; 343 printf("source_%s := %s\n\n", 344 target, m); 345 printf("deps_%s := \\\n", target); 346 } 347 is_first_dep = 0; 348 } else { 349 printf(" %s \\\n", m); 350 } 351 352 buf = read_file(m); 353 parse_config_file(buf); 354 free(buf); 355 } 356 357 if (is_last) 358 break; 359 360 /* 361 * Start searching for next token immediately after the first 362 * "whitespace" character that follows this token. 363 */ 364 m = p + 1; 365 } 366 367 if (!saw_any_target) { 368 fprintf(stderr, "fixdep: parse error; no targets found\n"); 369 exit(1); 370 } 371 372 if (insert_extra_deps) 373 do_extra_deps(); 374 375 printf("\n%s: $(deps_%s)\n\n", target, target); 376 printf("$(deps_%s):\n", target); 377 } 378 379 int main(int argc, char *argv[]) 380 { 381 const char *depfile, *target, *cmdline; 382 int insert_extra_deps = 0; 383 void *buf; 384 385 if (argc == 5 && !strcmp(argv[1], "-e")) { 386 insert_extra_deps = 1; 387 argv++; 388 } else if (argc != 4) 389 usage(); 390 391 depfile = argv[1]; 392 target = argv[2]; 393 cmdline = argv[3]; 394 395 printf("cmd_%s := %s\n\n", target, cmdline); 396 397 buf = read_file(depfile); 398 parse_dep_file(buf, target, insert_extra_deps); 399 free(buf); 400 401 return 0; 402 } 403