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 * We don't even try to really parse the header files, but 81 * merely grep, i.e. if CONFIG_FOO is mentioned in a comment, it will 82 * be picked up as well. It's not a problem with respect to 83 * correctness, since that can only give too many dependencies, thus 84 * we cannot miss a rebuild. Since people tend to not mention totally 85 * unrelated CONFIG_ options all over the place, it's not an 86 * efficiency problem either. 87 * 88 * (Note: it'd be easy to port over the complete mkdep state machine, 89 * but I don't think the added complexity is worth it) 90 */ 91 92#include <sys/types.h> 93#include <sys/stat.h> 94#include <unistd.h> 95#include <fcntl.h> 96#include <string.h> 97#include <stdarg.h> 98#include <stdlib.h> 99#include <stdio.h> 100#include <ctype.h> 101 102char tmp_buf[256]; /* hack for U-Boot */ 103 104static void usage(void) 105{ 106 fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n"); 107 exit(1); 108} 109 110/* 111 * In the intended usage of this program, the stdout is redirected to .*.cmd 112 * files. The return value of printf() and putchar() must be checked to catch 113 * any error, e.g. "No space left on device". 114 */ 115static void xprintf(const char *format, ...) 116{ 117 va_list ap; 118 int ret; 119 120 va_start(ap, format); 121 ret = vprintf(format, ap); 122 if (ret < 0) { 123 perror("fixdep"); 124 exit(1); 125 } 126 va_end(ap); 127} 128 129static void xputchar(int c) 130{ 131 int ret; 132 133 ret = putchar(c); 134 if (ret == EOF) { 135 perror("fixdep"); 136 exit(1); 137 } 138} 139 140/* 141 * Print out a dependency path from a symbol name 142 */ 143static void print_dep(const char *m, int slen, const char *dir) 144{ 145 int c, prev_c = '/', i; 146 147 xprintf(" $(wildcard %s/", dir); 148 for (i = 0; i < slen; i++) { 149 c = m[i]; 150 if (c == '_') 151 c = '/'; 152 else 153 c = tolower(c); 154 if (c != '/' || prev_c != '/') 155 xputchar(c); 156 prev_c = c; 157 } 158 xprintf(".h) \\\n"); 159} 160 161struct item { 162 struct item *next; 163 unsigned int len; 164 unsigned int hash; 165 char name[0]; 166}; 167 168#define HASHSZ 256 169static struct item *hashtab[HASHSZ]; 170 171static unsigned int strhash(const char *str, unsigned int sz) 172{ 173 /* fnv32 hash */ 174 unsigned int i, hash = 2166136261U; 175 176 for (i = 0; i < sz; i++) 177 hash = (hash ^ str[i]) * 0x01000193; 178 return hash; 179} 180 181/* 182 * Lookup a value in the configuration string. 183 */ 184static int is_defined_config(const char *name, int len, unsigned int hash) 185{ 186 struct item *aux; 187 188 for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) { 189 if (aux->hash == hash && aux->len == len && 190 memcmp(aux->name, name, len) == 0) 191 return 1; 192 } 193 return 0; 194} 195 196/* 197 * Add a new value to the configuration string. 198 */ 199static void define_config(const char *name, int len, unsigned int hash) 200{ 201 struct item *aux = malloc(sizeof(*aux) + len); 202 203 if (!aux) { 204 perror("fixdep:malloc"); 205 exit(1); 206 } 207 memcpy(aux->name, name, len); 208 aux->len = len; 209 aux->hash = hash; 210 aux->next = hashtab[hash % HASHSZ]; 211 hashtab[hash % HASHSZ] = aux; 212} 213 214/* 215 * Record the use of a CONFIG_* word. 216 */ 217static void use_config(const char *m, int slen) 218{ 219 unsigned int hash = strhash(m, slen); 220 221 if (is_defined_config(m, slen, hash)) 222 return; 223 224 define_config(m, slen, hash); 225 print_dep(m, slen, "include/config"); 226} 227 228/* test if s ends in sub */ 229static int str_ends_with(const char *s, int slen, const char *sub) 230{ 231 int sublen = strlen(sub); 232 233 if (sublen > slen) 234 return 0; 235 236 return !memcmp(s + slen - sublen, sub, sublen); 237} 238 239static void parse_config_file(const char *p) 240{ 241 const char *q, *r; 242 const char *start = p; 243 244 while ((p = strstr(p, "CONFIG_"))) { 245 if (p > start && (isalnum(p[-1]) || p[-1] == '_')) { 246 p += 7; 247 continue; 248 } 249 p += 7; 250 q = p; 251 while (isalnum(*q) || *q == '_') 252 q++; 253 if (str_ends_with(p, q - p, "_MODULE")) 254 r = q - 7; 255 else 256 r = q; 257 /* 258 * U-Boot also handles 259 * CONFIG_IS_ENABLED(...) 260 * CONFIG_VAL(...) 261 */ 262 if ((q - p == 10 && !memcmp(p, "IS_ENABLED(", 11)) || 263 (q - p == 3 && !memcmp(p, "VAL(", 4))) { 264 p = q + 1; 265 q = p; 266 while (isalnum(*q) || *q == '_') 267 q++; 268 r = q; 269 if (r > p && tmp_buf[0]) { 270 memcpy(tmp_buf + 4, p, r - p); 271 r = tmp_buf + 4 + (r - p); 272 p = tmp_buf; 273 } 274 } 275 /* end U-Boot hack */ 276 277 if (r > p) 278 use_config(p, r - p); 279 p = q; 280 } 281} 282 283static void *read_file(const char *filename) 284{ 285 struct stat st; 286 int fd; 287 char *buf; 288 289 fd = open(filename, O_RDONLY); 290 if (fd < 0) { 291 fprintf(stderr, "fixdep: error opening file: "); 292 perror(filename); 293 exit(2); 294 } 295 if (fstat(fd, &st) < 0) { 296 fprintf(stderr, "fixdep: error fstat'ing file: "); 297 perror(filename); 298 exit(2); 299 } 300 buf = malloc(st.st_size + 1); 301 if (!buf) { 302 perror("fixdep: malloc"); 303 exit(2); 304 } 305 if (read(fd, buf, st.st_size) != st.st_size) { 306 perror("fixdep: read"); 307 exit(2); 308 } 309 buf[st.st_size] = '\0'; 310 close(fd); 311 312 return buf; 313} 314 315/* Ignore certain dependencies */ 316static int is_ignored_file(const char *s, int len) 317{ 318 return str_ends_with(s, len, "include/generated/autoconf.h") || 319 str_ends_with(s, len, "include/generated/autoksyms.h"); 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 */ 327static void parse_dep_file(char *m, const char *target) 328{ 329 char *p; 330 int is_last, is_target; 331 int saw_any_target = 0; 332 int is_first_dep = 0; 333 void *buf; 334 335 while (1) { 336 /* Skip any "white space" */ 337 while (*m == ' ' || *m == '\\' || *m == '\n') 338 m++; 339 340 if (!*m) 341 break; 342 343 /* Find next "white space" */ 344 p = m; 345 while (*p && *p != ' ' && *p != '\\' && *p != '\n') 346 p++; 347 is_last = (*p == '\0'); 348 /* Is the token we found a target name? */ 349 is_target = (*(p-1) == ':'); 350 /* Don't write any target names into the dependency file */ 351 if (is_target) { 352 /* The /next/ file is the first dependency */ 353 is_first_dep = 1; 354 } else if (!is_ignored_file(m, p - m)) { 355 *p = '\0'; 356 357 /* 358 * Do not list the source file as dependency, so that 359 * kbuild is not confused if a .c file is rewritten 360 * into .S or vice versa. Storing it in source_* is 361 * needed for modpost to compute srcversions. 362 */ 363 if (is_first_dep) { 364 /* 365 * If processing the concatenation of multiple 366 * dependency files, only process the first 367 * target name, which will be the original 368 * source name, and ignore any other target 369 * names, which will be intermediate temporary 370 * files. 371 */ 372 if (!saw_any_target) { 373 saw_any_target = 1; 374 xprintf("source_%s := %s\n\n", 375 target, m); 376 xprintf("deps_%s := \\\n", target); 377 } 378 is_first_dep = 0; 379 } else { 380 xprintf(" %s \\\n", m); 381 } 382 383 buf = read_file(m); 384 parse_config_file(buf); 385 free(buf); 386 } 387 388 if (is_last) 389 break; 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 xprintf("\n%s: $(deps_%s)\n\n", target, target); 404 xprintf("$(deps_%s):\n", target); 405} 406 407int main(int argc, char *argv[]) 408{ 409 const char *depfile, *target, *cmdline; 410 void *buf; 411 412 if (argc != 4) 413 usage(); 414 415 depfile = argv[1]; 416 target = argv[2]; 417 cmdline = argv[3]; 418 419 /* hack for U-Boot */ 420 if (!strncmp(target, "spl/", 4)) 421 strcpy(tmp_buf, "SPL_"); 422 else if (!strncmp(target, "tpl/", 4)) 423 strcpy(tmp_buf, "TPL_"); 424 /* end U-Boot hack */ 425 426 xprintf("cmd_%s := %s\n\n", target, cmdline); 427 428 buf = read_file(depfile); 429 parse_dep_file(buf, target); 430 free(buf); 431 432 return 0; 433} 434