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
usage(void)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 */
print_cmdline(void)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
strhash(const char * str,unsigned int sz)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 */
is_defined_config(const char * name,int len,unsigned int hash)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 */
define_config(const char * name,int len,unsigned int hash)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 */
use_config(const char * m,int slen)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
parse_config_file(const char * map,size_t len)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 /*
253 * U-Boot also handles
254 * CONFIG_IS_ENABLED(...)
255 * CONFIG_IS_BUILTIN(...)
256 * CONFIG_IS_MODULE(...)
257 * CONFIG_VAL(...)
258 */
259 if ((q - p == 10 && !memcmp(p, "IS_ENABLED(", 11)) ||
260 (q - p == 10 && !memcmp(p, "IS_BUILTIN(", 11)) ||
261 (q - p == 9 && !memcmp(p, "IS_MODULE(", 10)) ||
262 (q - p == 3 && !memcmp(p, "VAL(", 4))) {
263 p = q + 1;
264 for (q = p; q < map + len; q++)
265 if (*q == ')')
266 goto found2;
267 continue;
268
269 found2:
270 if (is_spl_build) {
271 memcpy(tmp_buf + 4, p, q - p);
272 q = tmp_buf + 4 + (q - p);
273 p = tmp_buf;
274 }
275 }
276 /* end U-Boot hack */
277
278 use_config(p, q - p);
279 }
280 }
281
282 /* test is s ends in sub */
strrcmp(char * s,char * sub)283 static int strrcmp(char *s, char *sub)
284 {
285 int slen = strlen(s);
286 int sublen = strlen(sub);
287
288 if (sublen > slen)
289 return 1;
290
291 return memcmp(s + slen - sublen, sub, sublen);
292 }
293
do_config_file(const char * filename)294 static void do_config_file(const char *filename)
295 {
296 struct stat st;
297 int fd;
298 void *map;
299
300 fd = open(filename, O_RDONLY);
301 if (fd < 0) {
302 fprintf(stderr, "fixdep: error opening config file: ");
303 perror(filename);
304 exit(2);
305 }
306 if (fstat(fd, &st) < 0) {
307 fprintf(stderr, "fixdep: error fstat'ing config file: ");
308 perror(filename);
309 exit(2);
310 }
311 if (st.st_size == 0) {
312 close(fd);
313 return;
314 }
315 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
316 if ((long) map == -1) {
317 perror("fixdep: mmap");
318 close(fd);
319 return;
320 }
321
322 parse_config_file(map, st.st_size);
323
324 munmap(map, st.st_size);
325
326 close(fd);
327 }
328
329 /*
330 * Important: The below generated source_foo.o and deps_foo.o variable
331 * assignments are parsed not only by make, but also by the rather simple
332 * parser in scripts/mod/sumversion.c.
333 */
parse_dep_file(void * map,size_t len)334 static void parse_dep_file(void *map, size_t len)
335 {
336 char *m = map;
337 char *end = m + len;
338 char *p;
339 char s[PATH_MAX];
340 int is_target;
341 int saw_any_target = 0;
342 int is_first_dep = 0;
343
344 while (m < end) {
345 /* Skip any "white space" */
346 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n'))
347 m++;
348 /* Find next "white space" */
349 p = m;
350 while (p < end && *p != ' ' && *p != '\\' && *p != '\n')
351 p++;
352 /* Is the token we found a target name? */
353 is_target = (*(p-1) == ':');
354 /* Don't write any target names into the dependency file */
355 if (is_target) {
356 /* The /next/ file is the first dependency */
357 is_first_dep = 1;
358 } else {
359 /* Save this token/filename */
360 memcpy(s, m, p-m);
361 s[p - m] = 0;
362
363 /* Ignore certain dependencies */
364 if (strrcmp(s, "include/generated/autoconf.h") &&
365 strrcmp(s, "arch/um/include/uml-config.h") &&
366 strrcmp(s, "include/linux/kconfig.h") &&
367 strrcmp(s, ".ver")) {
368 /*
369 * Do not list the source file as dependency,
370 * so that kbuild is not confused if a .c file
371 * is rewritten into .S or vice versa. Storing
372 * it in source_* is needed for modpost to
373 * compute srcversions.
374 */
375 if (is_first_dep) {
376 /*
377 * If processing the concatenation of
378 * multiple dependency files, only
379 * process the first target name, which
380 * will be the original source name,
381 * and ignore any other target names,
382 * which will be intermediate temporary
383 * files.
384 */
385 if (!saw_any_target) {
386 saw_any_target = 1;
387 printf("source_%s := %s\n\n",
388 target, s);
389 printf("deps_%s := \\\n",
390 target);
391 }
392 is_first_dep = 0;
393 } else
394 printf(" %s \\\n", s);
395 do_config_file(s);
396 }
397 }
398 /*
399 * Start searching for next token immediately after the first
400 * "whitespace" character that follows this token.
401 */
402 m = p + 1;
403 }
404
405 if (!saw_any_target) {
406 fprintf(stderr, "fixdep: parse error; no targets found\n");
407 exit(1);
408 }
409
410 printf("\n%s: $(deps_%s)\n\n", target, target);
411 printf("$(deps_%s):\n", target);
412 }
413
print_deps(void)414 static void print_deps(void)
415 {
416 struct stat st;
417 int fd;
418 void *map;
419
420 fd = open(depfile, O_RDONLY);
421 if (fd < 0) {
422 fprintf(stderr, "fixdep: error opening depfile: ");
423 perror(depfile);
424 exit(2);
425 }
426 if (fstat(fd, &st) < 0) {
427 fprintf(stderr, "fixdep: error fstat'ing depfile: ");
428 perror(depfile);
429 exit(2);
430 }
431 if (st.st_size == 0) {
432 fprintf(stderr,"fixdep: %s is empty\n",depfile);
433 close(fd);
434 return;
435 }
436 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
437 if ((long) map == -1) {
438 perror("fixdep: mmap");
439 close(fd);
440 return;
441 }
442
443 parse_dep_file(map, st.st_size);
444
445 munmap(map, st.st_size);
446
447 close(fd);
448 }
449
traps(void)450 static void traps(void)
451 {
452 static char test[] __attribute__((aligned(sizeof(int)))) = "CONF";
453 int *p = (int *)test;
454
455 if (*p != INT_CONF) {
456 fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianness? %#x\n",
457 *p);
458 exit(2);
459 }
460 }
461
main(int argc,char * argv[])462 int main(int argc, char *argv[])
463 {
464 traps();
465
466 if (argc != 4)
467 usage();
468
469 depfile = argv[1];
470 target = argv[2];
471 cmdline = argv[3];
472
473 /* hack for U-Boot */
474 if (!strncmp(target, "spl/", 4) || !strncmp(target, "tpl/", 4))
475 is_spl_build = 1;
476
477 print_cmdline();
478 print_deps();
479
480 return 0;
481 }
482