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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 | |
127 | static void usage(void) |
128 | { |
129 | fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n"); |
130 | exit(1); |
131 | } |
132 | |
133 | /* |
134 | * Print out the commandline prefixed with cmd_<target filename> := |
135 | */ |
136 | static void print_cmdline(void) |
137 | { |
138 | printf("cmd_%s := %s\n\n", target, cmdline); |
139 | } |
140 | |
141 | struct item { |
142 | struct item *next; |
143 | unsigned int len; |
144 | unsigned int hash; |
145 | char name[0]; |
146 | }; |
147 | |
148 | #define HASHSZ 256 |
149 | static struct item *hashtab[HASHSZ]; |
150 | |
151 | static unsigned int strhash(const char *str, unsigned int sz) |
152 | { |
153 | /* fnv32 hash */ |
154 | unsigned int i, hash = 2166136261U; |
155 | |
156 | for (i = 0; i < sz; i++) |
157 | hash = (hash ^ str[i]) * 0x01000193; |
158 | return hash; |
159 | } |
160 | |
161 | /* |
162 | * Lookup a value in the configuration string. |
163 | */ |
164 | static int is_defined_config(const char *name, int len, unsigned int hash) |
165 | { |
166 | struct item *aux; |
167 | |
168 | for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) { |
169 | if (aux->hash == hash && aux->len == len && |
170 | memcmp(aux->name, name, len) == 0) |
171 | return 1; |
172 | } |
173 | return 0; |
174 | } |
175 | |
176 | /* |
177 | * Add a new value to the configuration string. |
178 | */ |
179 | static void define_config(const char *name, int len, unsigned int hash) |
180 | { |
181 | struct item *aux = malloc(sizeof(*aux) + len); |
182 | |
183 | if (!aux) { |
184 | perror("fixdep:malloc"); |
185 | exit(1); |
186 | } |
187 | memcpy(aux->name, name, len); |
188 | aux->len = len; |
189 | aux->hash = hash; |
190 | aux->next = hashtab[hash % HASHSZ]; |
191 | hashtab[hash % HASHSZ] = aux; |
192 | } |
193 | |
194 | /* |
195 | * Clear the set of configuration strings. |
196 | */ |
197 | static void clear_config(void) |
198 | { |
199 | struct item *aux, *next; |
200 | unsigned int i; |
201 | |
202 | for (i = 0; i < HASHSZ; i++) { |
203 | for (aux = hashtab[i]; aux; aux = next) { |
204 | next = aux->next; |
205 | free(aux); |
206 | } |
207 | hashtab[i] = NULL; |
208 | } |
209 | } |
210 | |
211 | /* |
212 | * Record the use of a CONFIG_* word. |
213 | */ |
214 | static void use_config(const char *m, int slen) |
215 | { |
216 | unsigned int hash = strhash(m, slen); |
217 | int c, i; |
218 | |
219 | if (is_defined_config(m, slen, hash)) |
220 | return; |
221 | |
222 | define_config(m, slen, hash); |
223 | |
224 | printf(" $(wildcard include/config/"); |
225 | for (i = 0; i < slen; i++) { |
226 | c = m[i]; |
227 | if (c == '_') |
228 | c = '/'; |
229 | else |
230 | c = tolower(c); |
231 | putchar(c); |
232 | } |
233 | printf(".h) \\\n"); |
234 | } |
235 | |
236 | static void parse_config_file(const char *map, size_t len) |
237 | { |
238 | const int *end = (const int *) (map + len); |
239 | /* start at +1, so that p can never be < map */ |
240 | const int *m = (const int *) map + 1; |
241 | const char *p, *q; |
242 | |
243 | for (; m < end; m++) { |
244 | if (*m == INT_CONF) { p = (char *) m ; goto conf; } |
245 | if (*m == INT_ONFI) { p = (char *) m-1; goto conf; } |
246 | if (*m == INT_NFIG) { p = (char *) m-2; goto conf; } |
247 | if (*m == INT_FIG_) { p = (char *) m-3; goto conf; } |
248 | continue; |
249 | conf: |
250 | if (p > map + len - 7) |
251 | continue; |
252 | if (memcmp(p, "CONFIG_", 7)) |
253 | continue; |
254 | for (q = p + 7; q < map + len; q++) { |
255 | if (!(isalnum(*q) || *q == '_')) |
256 | goto found; |
257 | } |
258 | continue; |
259 | |
260 | found: |
261 | if (!memcmp(q - 7, "_MODULE", 7)) |
262 | q -= 7; |
263 | if( (q-p-7) < 0 ) |
264 | continue; |
265 | use_config(p+7, q-p-7); |
266 | } |
267 | } |
268 | |
269 | /* test is s ends in sub */ |
270 | static int strrcmp(char *s, char *sub) |
271 | { |
272 | int slen = strlen(s); |
273 | int sublen = strlen(sub); |
274 | |
275 | if (sublen > slen) |
276 | return 1; |
277 | |
278 | return memcmp(s + slen - sublen, sub, sublen); |
279 | } |
280 | |
281 | static void do_config_file(const char *filename) |
282 | { |
283 | struct stat st; |
284 | int fd; |
285 | void *map; |
286 | |
287 | fd = open(filename, O_RDONLY); |
288 | if (fd < 0) { |
289 | fprintf(stderr, "fixdep: error opening config file: "); |
290 | perror(filename); |
291 | exit(2); |
292 | } |
293 | fstat(fd, &st); |
294 | if (st.st_size == 0) { |
295 | close(fd); |
296 | return; |
297 | } |
298 | map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); |
299 | if ((long) map == -1) { |
300 | perror("fixdep: mmap"); |
301 | close(fd); |
302 | return; |
303 | } |
304 | |
305 | parse_config_file(map, st.st_size); |
306 | |
307 | munmap(map, st.st_size); |
308 | |
309 | close(fd); |
310 | } |
311 | |
312 | /* |
313 | * Important: The below generated source_foo.o and deps_foo.o variable |
314 | * assignments are parsed not only by make, but also by the rather simple |
315 | * parser in scripts/mod/sumversion.c. |
316 | */ |
317 | static void parse_dep_file(void *map, size_t len) |
318 | { |
319 | char *m = map; |
320 | char *end = m + len; |
321 | char *p; |
322 | char s[PATH_MAX]; |
323 | int first; |
324 | |
325 | p = strchr(m, ':'); |
326 | if (!p) { |
327 | fprintf(stderr, "fixdep: parse error\n"); |
328 | exit(1); |
329 | } |
330 | memcpy(s, m, p-m); s[p-m] = 0; |
331 | m = p+1; |
332 | |
333 | clear_config(); |
334 | |
335 | first = 1; |
336 | while (m < end) { |
337 | while (m < end && (*m == ' ' || *m == '\\' || *m == '\n')) |
338 | m++; |
339 | p = m; |
340 | while (p < end && *p != ' ') p++; |
341 | if (p == end) { |
342 | do p--; while (!isalnum(*p)); |
343 | p++; |
344 | } |
345 | memcpy(s, m, p-m); s[p-m] = 0; |
346 | if (strrcmp(s, "include/generated/autoconf.h") && |
347 | strrcmp(s, "arch/um/include/uml-config.h") && |
348 | strrcmp(s, ".ver")) { |
349 | /* |
350 | * Do not list the source file as dependency, so that |
351 | * kbuild is not confused if a .c file is rewritten |
352 | * into .S or vice versa. Storing it in source_* is |
353 | * needed for modpost to compute srcversions. |
354 | */ |
355 | if (first) { |
356 | printf("source_%s := %s\n\n", target, s); |
357 | printf("deps_%s := \\\n", target); |
358 | } else |
359 | printf(" %s \\\n", s); |
360 | do_config_file(s); |
361 | } |
362 | first = 0; |
363 | m = p + 1; |
364 | } |
365 | printf("\n%s: $(deps_%s)\n\n", target, target); |
366 | printf("$(deps_%s):\n", target); |
367 | } |
368 | |
369 | static void print_deps(void) |
370 | { |
371 | struct stat st; |
372 | int fd; |
373 | void *map; |
374 | |
375 | fd = open(depfile, O_RDONLY); |
376 | if (fd < 0) { |
377 | fprintf(stderr, "fixdep: error opening depfile: "); |
378 | perror(depfile); |
379 | exit(2); |
380 | } |
381 | if (fstat(fd, &st) < 0) { |
382 | fprintf(stderr, "fixdep: error fstat'ing depfile: "); |
383 | perror(depfile); |
384 | exit(2); |
385 | } |
386 | if (st.st_size == 0) { |
387 | fprintf(stderr,"fixdep: %s is empty\n",depfile); |
388 | close(fd); |
389 | return; |
390 | } |
391 | map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); |
392 | if ((long) map == -1) { |
393 | perror("fixdep: mmap"); |
394 | close(fd); |
395 | return; |
396 | } |
397 | |
398 | parse_dep_file(map, st.st_size); |
399 | |
400 | munmap(map, st.st_size); |
401 | |
402 | close(fd); |
403 | } |
404 | |
405 | static void traps(void) |
406 | { |
407 | static char test[] __attribute__((aligned(sizeof(int)))) = "CONF"; |
408 | int *p = (int *)test; |
409 | |
410 | if (*p != INT_CONF) { |
411 | fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianess? %#x\n", |
412 | *p); |
413 | exit(2); |
414 | } |
415 | } |
416 | |
417 | int main(int argc, char *argv[]) |
418 | { |
419 | traps(); |
420 | |
421 | if (argc != 4) |
422 | usage(); |
423 | |
424 | depfile = argv[1]; |
425 | target = argv[2]; |
426 | cmdline = argv[3]; |
427 | |
428 | print_cmdline(); |
429 | print_deps(); |
430 | |
431 | return 0; |
432 | } |
433 |
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