xref: /linux/scripts/mod/modpost.c (revision a7edd0e676d51145ae634a2acf7a447e319200fa)
1 /* Postprocess module symbol versions
2  *
3  * Copyright 2003       Kai Germaschewski
4  * Copyright 2002-2004  Rusty Russell, IBM Corporation
5  * Copyright 2006       Sam Ravnborg
6  * Based in part on module-init-tools/depmod.c,file2alias
7  *
8  * This software may be used and distributed according to the terms
9  * of the GNU General Public License, incorporated herein by reference.
10  *
11  * Usage: modpost vmlinux module1.o module2.o ...
12  */
13 
14 #include <ctype.h>
15 #include "modpost.h"
16 #include "../../include/linux/license.h"
17 
18 /* Are we using CONFIG_MODVERSIONS? */
19 int modversions = 0;
20 /* Warn about undefined symbols? (do so if we have vmlinux) */
21 int have_vmlinux = 0;
22 /* Is CONFIG_MODULE_SRCVERSION_ALL set? */
23 static int all_versions = 0;
24 /* If we are modposting external module set to 1 */
25 static int external_module = 0;
26 /* Only warn about unresolved symbols */
27 static int warn_unresolved = 0;
28 /* How a symbol is exported */
29 enum export {
30 	export_plain,      export_unused,     export_gpl,
31 	export_unused_gpl, export_gpl_future, export_unknown
32 };
33 
34 void fatal(const char *fmt, ...)
35 {
36 	va_list arglist;
37 
38 	fprintf(stderr, "FATAL: ");
39 
40 	va_start(arglist, fmt);
41 	vfprintf(stderr, fmt, arglist);
42 	va_end(arglist);
43 
44 	exit(1);
45 }
46 
47 void warn(const char *fmt, ...)
48 {
49 	va_list arglist;
50 
51 	fprintf(stderr, "WARNING: ");
52 
53 	va_start(arglist, fmt);
54 	vfprintf(stderr, fmt, arglist);
55 	va_end(arglist);
56 }
57 
58 static int is_vmlinux(const char *modname)
59 {
60 	const char *myname;
61 
62 	if ((myname = strrchr(modname, '/')))
63 		myname++;
64 	else
65 		myname = modname;
66 
67 	return strcmp(myname, "vmlinux") == 0;
68 }
69 
70 void *do_nofail(void *ptr, const char *expr)
71 {
72 	if (!ptr) {
73 		fatal("modpost: Memory allocation failure: %s.\n", expr);
74 	}
75 	return ptr;
76 }
77 
78 /* A list of all modules we processed */
79 
80 static struct module *modules;
81 
82 static struct module *find_module(char *modname)
83 {
84 	struct module *mod;
85 
86 	for (mod = modules; mod; mod = mod->next)
87 		if (strcmp(mod->name, modname) == 0)
88 			break;
89 	return mod;
90 }
91 
92 static struct module *new_module(char *modname)
93 {
94 	struct module *mod;
95 	char *p, *s;
96 
97 	mod = NOFAIL(malloc(sizeof(*mod)));
98 	memset(mod, 0, sizeof(*mod));
99 	p = NOFAIL(strdup(modname));
100 
101 	/* strip trailing .o */
102 	if ((s = strrchr(p, '.')) != NULL)
103 		if (strcmp(s, ".o") == 0)
104 			*s = '\0';
105 
106 	/* add to list */
107 	mod->name = p;
108 	mod->gpl_compatible = -1;
109 	mod->next = modules;
110 	modules = mod;
111 
112 	return mod;
113 }
114 
115 /* A hash of all exported symbols,
116  * struct symbol is also used for lists of unresolved symbols */
117 
118 #define SYMBOL_HASH_SIZE 1024
119 
120 struct symbol {
121 	struct symbol *next;
122 	struct module *module;
123 	unsigned int crc;
124 	int crc_valid;
125 	unsigned int weak:1;
126 	unsigned int vmlinux:1;    /* 1 if symbol is defined in vmlinux */
127 	unsigned int kernel:1;     /* 1 if symbol is from kernel
128 				    *  (only for external modules) **/
129 	unsigned int preloaded:1;  /* 1 if symbol from Module.symvers */
130 	enum export  export;       /* Type of export */
131 	char name[0];
132 };
133 
134 static struct symbol *symbolhash[SYMBOL_HASH_SIZE];
135 
136 /* This is based on the hash agorithm from gdbm, via tdb */
137 static inline unsigned int tdb_hash(const char *name)
138 {
139 	unsigned value;	/* Used to compute the hash value.  */
140 	unsigned   i;	/* Used to cycle through random values. */
141 
142 	/* Set the initial value from the key size. */
143 	for (value = 0x238F13AF * strlen(name), i=0; name[i]; i++)
144 		value = (value + (((unsigned char *)name)[i] << (i*5 % 24)));
145 
146 	return (1103515243 * value + 12345);
147 }
148 
149 /**
150  * Allocate a new symbols for use in the hash of exported symbols or
151  * the list of unresolved symbols per module
152  **/
153 static struct symbol *alloc_symbol(const char *name, unsigned int weak,
154 				   struct symbol *next)
155 {
156 	struct symbol *s = NOFAIL(malloc(sizeof(*s) + strlen(name) + 1));
157 
158 	memset(s, 0, sizeof(*s));
159 	strcpy(s->name, name);
160 	s->weak = weak;
161 	s->next = next;
162 	return s;
163 }
164 
165 /* For the hash of exported symbols */
166 static struct symbol *new_symbol(const char *name, struct module *module,
167 				 enum export export)
168 {
169 	unsigned int hash;
170 	struct symbol *new;
171 
172 	hash = tdb_hash(name) % SYMBOL_HASH_SIZE;
173 	new = symbolhash[hash] = alloc_symbol(name, 0, symbolhash[hash]);
174 	new->module = module;
175 	new->export = export;
176 	return new;
177 }
178 
179 static struct symbol *find_symbol(const char *name)
180 {
181 	struct symbol *s;
182 
183 	/* For our purposes, .foo matches foo.  PPC64 needs this. */
184 	if (name[0] == '.')
185 		name++;
186 
187 	for (s = symbolhash[tdb_hash(name) % SYMBOL_HASH_SIZE]; s; s=s->next) {
188 		if (strcmp(s->name, name) == 0)
189 			return s;
190 	}
191 	return NULL;
192 }
193 
194 static struct {
195 	const char *str;
196 	enum export export;
197 } export_list[] = {
198 	{ .str = "EXPORT_SYMBOL",            .export = export_plain },
199 	{ .str = "EXPORT_UNUSED_SYMBOL",     .export = export_unused },
200 	{ .str = "EXPORT_SYMBOL_GPL",        .export = export_gpl },
201 	{ .str = "EXPORT_UNUSED_SYMBOL_GPL", .export = export_unused_gpl },
202 	{ .str = "EXPORT_SYMBOL_GPL_FUTURE", .export = export_gpl_future },
203 	{ .str = "(unknown)",                .export = export_unknown },
204 };
205 
206 
207 static const char *export_str(enum export ex)
208 {
209 	return export_list[ex].str;
210 }
211 
212 static enum export export_no(const char * s)
213 {
214 	int i;
215 	if (!s)
216 		return export_unknown;
217 	for (i = 0; export_list[i].export != export_unknown; i++) {
218 		if (strcmp(export_list[i].str, s) == 0)
219 			return export_list[i].export;
220 	}
221 	return export_unknown;
222 }
223 
224 static enum export export_from_sec(struct elf_info *elf, Elf_Section sec)
225 {
226 	if (sec == elf->export_sec)
227 		return export_plain;
228 	else if (sec == elf->export_unused_sec)
229 		return export_unused;
230 	else if (sec == elf->export_gpl_sec)
231 		return export_gpl;
232 	else if (sec == elf->export_unused_gpl_sec)
233 		return export_unused_gpl;
234 	else if (sec == elf->export_gpl_future_sec)
235 		return export_gpl_future;
236 	else
237 		return export_unknown;
238 }
239 
240 /**
241  * Add an exported symbol - it may have already been added without a
242  * CRC, in this case just update the CRC
243  **/
244 static struct symbol *sym_add_exported(const char *name, struct module *mod,
245 				       enum export export)
246 {
247 	struct symbol *s = find_symbol(name);
248 
249 	if (!s) {
250 		s = new_symbol(name, mod, export);
251 	} else {
252 		if (!s->preloaded) {
253 			warn("%s: '%s' exported twice. Previous export "
254 			     "was in %s%s\n", mod->name, name,
255 			     s->module->name,
256 			     is_vmlinux(s->module->name) ?"":".ko");
257 		}
258 	}
259 	s->preloaded = 0;
260 	s->vmlinux   = is_vmlinux(mod->name);
261 	s->kernel    = 0;
262 	s->export    = export;
263 	return s;
264 }
265 
266 static void sym_update_crc(const char *name, struct module *mod,
267 			   unsigned int crc, enum export export)
268 {
269 	struct symbol *s = find_symbol(name);
270 
271 	if (!s)
272 		s = new_symbol(name, mod, export);
273 	s->crc = crc;
274 	s->crc_valid = 1;
275 }
276 
277 void *grab_file(const char *filename, unsigned long *size)
278 {
279 	struct stat st;
280 	void *map;
281 	int fd;
282 
283 	fd = open(filename, O_RDONLY);
284 	if (fd < 0 || fstat(fd, &st) != 0)
285 		return NULL;
286 
287 	*size = st.st_size;
288 	map = mmap(NULL, *size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
289 	close(fd);
290 
291 	if (map == MAP_FAILED)
292 		return NULL;
293 	return map;
294 }
295 
296 /**
297   * Return a copy of the next line in a mmap'ed file.
298   * spaces in the beginning of the line is trimmed away.
299   * Return a pointer to a static buffer.
300   **/
301 char* get_next_line(unsigned long *pos, void *file, unsigned long size)
302 {
303 	static char line[4096];
304 	int skip = 1;
305 	size_t len = 0;
306 	signed char *p = (signed char *)file + *pos;
307 	char *s = line;
308 
309 	for (; *pos < size ; (*pos)++)
310 	{
311 		if (skip && isspace(*p)) {
312 			p++;
313 			continue;
314 		}
315 		skip = 0;
316 		if (*p != '\n' && (*pos < size)) {
317 			len++;
318 			*s++ = *p++;
319 			if (len > 4095)
320 				break; /* Too long, stop */
321 		} else {
322 			/* End of string */
323 			*s = '\0';
324 			return line;
325 		}
326 	}
327 	/* End of buffer */
328 	return NULL;
329 }
330 
331 void release_file(void *file, unsigned long size)
332 {
333 	munmap(file, size);
334 }
335 
336 static void parse_elf(struct elf_info *info, const char *filename)
337 {
338 	unsigned int i;
339 	Elf_Ehdr *hdr = info->hdr;
340 	Elf_Shdr *sechdrs;
341 	Elf_Sym  *sym;
342 
343 	hdr = grab_file(filename, &info->size);
344 	if (!hdr) {
345 		perror(filename);
346 		exit(1);
347 	}
348 	info->hdr = hdr;
349 	if (info->size < sizeof(*hdr))
350 		goto truncated;
351 
352 	/* Fix endianness in ELF header */
353 	hdr->e_shoff    = TO_NATIVE(hdr->e_shoff);
354 	hdr->e_shstrndx = TO_NATIVE(hdr->e_shstrndx);
355 	hdr->e_shnum    = TO_NATIVE(hdr->e_shnum);
356 	hdr->e_machine  = TO_NATIVE(hdr->e_machine);
357 	sechdrs = (void *)hdr + hdr->e_shoff;
358 	info->sechdrs = sechdrs;
359 
360 	/* Fix endianness in section headers */
361 	for (i = 0; i < hdr->e_shnum; i++) {
362 		sechdrs[i].sh_type   = TO_NATIVE(sechdrs[i].sh_type);
363 		sechdrs[i].sh_offset = TO_NATIVE(sechdrs[i].sh_offset);
364 		sechdrs[i].sh_size   = TO_NATIVE(sechdrs[i].sh_size);
365 		sechdrs[i].sh_link   = TO_NATIVE(sechdrs[i].sh_link);
366 		sechdrs[i].sh_name   = TO_NATIVE(sechdrs[i].sh_name);
367 	}
368 	/* Find symbol table. */
369 	for (i = 1; i < hdr->e_shnum; i++) {
370 		const char *secstrings
371 			= (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
372 		const char *secname;
373 
374 		if (sechdrs[i].sh_offset > info->size)
375 			goto truncated;
376 		secname = secstrings + sechdrs[i].sh_name;
377 		if (strcmp(secname, ".modinfo") == 0) {
378 			info->modinfo = (void *)hdr + sechdrs[i].sh_offset;
379 			info->modinfo_len = sechdrs[i].sh_size;
380 		} else if (strcmp(secname, "__ksymtab") == 0)
381 			info->export_sec = i;
382 		else if (strcmp(secname, "__ksymtab_unused") == 0)
383 			info->export_unused_sec = i;
384 		else if (strcmp(secname, "__ksymtab_gpl") == 0)
385 			info->export_gpl_sec = i;
386 		else if (strcmp(secname, "__ksymtab_unused_gpl") == 0)
387 			info->export_unused_gpl_sec = i;
388 		else if (strcmp(secname, "__ksymtab_gpl_future") == 0)
389 			info->export_gpl_future_sec = i;
390 
391 		if (sechdrs[i].sh_type != SHT_SYMTAB)
392 			continue;
393 
394 		info->symtab_start = (void *)hdr + sechdrs[i].sh_offset;
395 		info->symtab_stop  = (void *)hdr + sechdrs[i].sh_offset
396 			                         + sechdrs[i].sh_size;
397 		info->strtab       = (void *)hdr +
398 			             sechdrs[sechdrs[i].sh_link].sh_offset;
399 	}
400 	if (!info->symtab_start) {
401 		fatal("%s has no symtab?\n", filename);
402 	}
403 	/* Fix endianness in symbols */
404 	for (sym = info->symtab_start; sym < info->symtab_stop; sym++) {
405 		sym->st_shndx = TO_NATIVE(sym->st_shndx);
406 		sym->st_name  = TO_NATIVE(sym->st_name);
407 		sym->st_value = TO_NATIVE(sym->st_value);
408 		sym->st_size  = TO_NATIVE(sym->st_size);
409 	}
410 	return;
411 
412  truncated:
413 	fatal("%s is truncated.\n", filename);
414 }
415 
416 static void parse_elf_finish(struct elf_info *info)
417 {
418 	release_file(info->hdr, info->size);
419 }
420 
421 #define CRC_PFX     MODULE_SYMBOL_PREFIX "__crc_"
422 #define KSYMTAB_PFX MODULE_SYMBOL_PREFIX "__ksymtab_"
423 
424 static void handle_modversions(struct module *mod, struct elf_info *info,
425 			       Elf_Sym *sym, const char *symname)
426 {
427 	unsigned int crc;
428 	enum export export = export_from_sec(info, sym->st_shndx);
429 
430 	switch (sym->st_shndx) {
431 	case SHN_COMMON:
432 		warn("\"%s\" [%s] is COMMON symbol\n", symname, mod->name);
433 		break;
434 	case SHN_ABS:
435 		/* CRC'd symbol */
436 		if (memcmp(symname, CRC_PFX, strlen(CRC_PFX)) == 0) {
437 			crc = (unsigned int) sym->st_value;
438 			sym_update_crc(symname + strlen(CRC_PFX), mod, crc,
439 					export);
440 		}
441 		break;
442 	case SHN_UNDEF:
443 		/* undefined symbol */
444 		if (ELF_ST_BIND(sym->st_info) != STB_GLOBAL &&
445 		    ELF_ST_BIND(sym->st_info) != STB_WEAK)
446 			break;
447 		/* ignore global offset table */
448 		if (strcmp(symname, "_GLOBAL_OFFSET_TABLE_") == 0)
449 			break;
450 		/* ignore __this_module, it will be resolved shortly */
451 		if (strcmp(symname, MODULE_SYMBOL_PREFIX "__this_module") == 0)
452 			break;
453 /* cope with newer glibc (2.3.4 or higher) STT_ definition in elf.h */
454 #if defined(STT_REGISTER) || defined(STT_SPARC_REGISTER)
455 /* add compatibility with older glibc */
456 #ifndef STT_SPARC_REGISTER
457 #define STT_SPARC_REGISTER STT_REGISTER
458 #endif
459 		if (info->hdr->e_machine == EM_SPARC ||
460 		    info->hdr->e_machine == EM_SPARCV9) {
461 			/* Ignore register directives. */
462 			if (ELF_ST_TYPE(sym->st_info) == STT_SPARC_REGISTER)
463 				break;
464 			if (symname[0] == '.') {
465 				char *munged = strdup(symname);
466 				munged[0] = '_';
467 				munged[1] = toupper(munged[1]);
468 				symname = munged;
469 			}
470 		}
471 #endif
472 
473 		if (memcmp(symname, MODULE_SYMBOL_PREFIX,
474 			   strlen(MODULE_SYMBOL_PREFIX)) == 0)
475 			mod->unres = alloc_symbol(symname +
476 						  strlen(MODULE_SYMBOL_PREFIX),
477 						  ELF_ST_BIND(sym->st_info) == STB_WEAK,
478 						  mod->unres);
479 		break;
480 	default:
481 		/* All exported symbols */
482 		if (memcmp(symname, KSYMTAB_PFX, strlen(KSYMTAB_PFX)) == 0) {
483 			sym_add_exported(symname + strlen(KSYMTAB_PFX), mod,
484 					export);
485 		}
486 		if (strcmp(symname, MODULE_SYMBOL_PREFIX "init_module") == 0)
487 			mod->has_init = 1;
488 		if (strcmp(symname, MODULE_SYMBOL_PREFIX "cleanup_module") == 0)
489 			mod->has_cleanup = 1;
490 		break;
491 	}
492 }
493 
494 /**
495  * Parse tag=value strings from .modinfo section
496  **/
497 static char *next_string(char *string, unsigned long *secsize)
498 {
499 	/* Skip non-zero chars */
500 	while (string[0]) {
501 		string++;
502 		if ((*secsize)-- <= 1)
503 			return NULL;
504 	}
505 
506 	/* Skip any zero padding. */
507 	while (!string[0]) {
508 		string++;
509 		if ((*secsize)-- <= 1)
510 			return NULL;
511 	}
512 	return string;
513 }
514 
515 static char *get_next_modinfo(void *modinfo, unsigned long modinfo_len,
516 			      const char *tag, char *info)
517 {
518 	char *p;
519 	unsigned int taglen = strlen(tag);
520 	unsigned long size = modinfo_len;
521 
522 	if (info) {
523 		size -= info - (char *)modinfo;
524 		modinfo = next_string(info, &size);
525 	}
526 
527 	for (p = modinfo; p; p = next_string(p, &size)) {
528 		if (strncmp(p, tag, taglen) == 0 && p[taglen] == '=')
529 			return p + taglen + 1;
530 	}
531 	return NULL;
532 }
533 
534 static char *get_modinfo(void *modinfo, unsigned long modinfo_len,
535 			 const char *tag)
536 
537 {
538 	return get_next_modinfo(modinfo, modinfo_len, tag, NULL);
539 }
540 
541 /**
542  * Test if string s ends in string sub
543  * return 0 if match
544  **/
545 static int strrcmp(const char *s, const char *sub)
546 {
547         int slen, sublen;
548 
549 	if (!s || !sub)
550 		return 1;
551 
552 	slen = strlen(s);
553         sublen = strlen(sub);
554 
555 	if ((slen == 0) || (sublen == 0))
556 		return 1;
557 
558         if (sublen > slen)
559                 return 1;
560 
561         return memcmp(s + slen - sublen, sub, sublen);
562 }
563 
564 /**
565  * Whitelist to allow certain references to pass with no warning.
566  * Pattern 1:
567  *   If a module parameter is declared __initdata and permissions=0
568  *   then this is legal despite the warning generated.
569  *   We cannot see value of permissions here, so just ignore
570  *   this pattern.
571  *   The pattern is identified by:
572  *   tosec   = .init.data
573  *   fromsec = .data*
574  *   atsym   =__param*
575  *
576  * Pattern 2:
577  *   Many drivers utilise a *driver container with references to
578  *   add, remove, probe functions etc.
579  *   These functions may often be marked __init and we do not want to
580  *   warn here.
581  *   the pattern is identified by:
582  *   tosec   = .init.text | .exit.text | .init.data
583  *   fromsec = .data
584  *   atsym = *driver, *_template, *_sht, *_ops, *_probe, *probe_one
585  *
586  * Pattern 3:
587  *   Some symbols belong to init section but still it is ok to reference
588  *   these from non-init sections as these symbols don't have any memory
589  *   allocated for them and symbol address and value are same. So even
590  *   if init section is freed, its ok to reference those symbols.
591  *   For ex. symbols marking the init section boundaries.
592  *   This pattern is identified by
593  *   refsymname = __init_begin, _sinittext, _einittext
594  **/
595 static int secref_whitelist(const char *modname, const char *tosec,
596 			    const char *fromsec, const char *atsym,
597 			    const char *refsymname)
598 {
599 	int f1 = 1, f2 = 1;
600 	const char **s;
601 	const char *pat2sym[] = {
602 		"driver",
603 		"_template", /* scsi uses *_template a lot */
604 		"_sht",      /* scsi also used *_sht to some extent */
605 		"_ops",
606 		"_probe",
607 		"_probe_one",
608 		"_console",
609 		NULL
610 	};
611 
612 	const char *pat3refsym[] = {
613 		"__init_begin",
614 		"_sinittext",
615 		"_einittext",
616 		NULL
617 	};
618 
619 	/* Check for pattern 1 */
620 	if (strcmp(tosec, ".init.data") != 0)
621 		f1 = 0;
622 	if (strncmp(fromsec, ".data", strlen(".data")) != 0)
623 		f1 = 0;
624 	if (strncmp(atsym, "__param", strlen("__param")) != 0)
625 		f1 = 0;
626 
627 	if (f1)
628 		return f1;
629 
630 	/* Check for pattern 2 */
631 	if ((strcmp(tosec, ".init.text") != 0) &&
632 	    (strcmp(tosec, ".exit.text") != 0) &&
633 	    (strcmp(tosec, ".init.data") != 0))
634 		f2 = 0;
635 	if (strcmp(fromsec, ".data") != 0)
636 		f2 = 0;
637 
638 	for (s = pat2sym; *s; s++)
639 		if (strrcmp(atsym, *s) == 0)
640 			f1 = 1;
641 	if (f1 && f2)
642 		return 1;
643 
644 	/* Whitelist all references from .pci_fixup section if vmlinux
645 	 * Whitelist all refereces from .text.head to .init.data if vmlinux
646 	 * Whitelist all refereces from .text.head to .init.text if vmlinux
647 	 */
648 	if (is_vmlinux(modname)) {
649 		if ((strcmp(fromsec, ".pci_fixup") == 0) &&
650 		    (strcmp(tosec, ".init.text") == 0))
651 		return 1;
652 
653 		if ((strcmp(fromsec, ".text.head") == 0) &&
654 			((strcmp(tosec, ".init.data") == 0) ||
655 			(strcmp(tosec, ".init.text") == 0)))
656 		return 1;
657 
658 		/* Check for pattern 3 */
659 		for (s = pat3refsym; *s; s++)
660 			if (strcmp(refsymname, *s) == 0)
661 				return 1;
662 	}
663 	return 0;
664 }
665 
666 /**
667  * Find symbol based on relocation record info.
668  * In some cases the symbol supplied is a valid symbol so
669  * return refsym. If st_name != 0 we assume this is a valid symbol.
670  * In other cases the symbol needs to be looked up in the symbol table
671  * based on section and address.
672  *  **/
673 static Elf_Sym *find_elf_symbol(struct elf_info *elf, Elf_Addr addr,
674 				Elf_Sym *relsym)
675 {
676 	Elf_Sym *sym;
677 
678 	if (relsym->st_name != 0)
679 		return relsym;
680 	for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) {
681 		if (sym->st_shndx != relsym->st_shndx)
682 			continue;
683 		if (sym->st_value == addr)
684 			return sym;
685 	}
686 	return NULL;
687 }
688 
689 static inline int is_arm_mapping_symbol(const char *str)
690 {
691 	return str[0] == '$' && strchr("atd", str[1])
692 	       && (str[2] == '\0' || str[2] == '.');
693 }
694 
695 /*
696  * If there's no name there, ignore it; likewise, ignore it if it's
697  * one of the magic symbols emitted used by current ARM tools.
698  *
699  * Otherwise if find_symbols_between() returns those symbols, they'll
700  * fail the whitelist tests and cause lots of false alarms ... fixable
701  * only by merging __exit and __init sections into __text, bloating
702  * the kernel (which is especially evil on embedded platforms).
703  */
704 static inline int is_valid_name(struct elf_info *elf, Elf_Sym *sym)
705 {
706 	const char *name = elf->strtab + sym->st_name;
707 
708 	if (!name || !strlen(name))
709 		return 0;
710 	return !is_arm_mapping_symbol(name);
711 }
712 
713 /*
714  * Find symbols before or equal addr and after addr - in the section sec.
715  * If we find two symbols with equal offset prefer one with a valid name.
716  * The ELF format may have a better way to detect what type of symbol
717  * it is, but this works for now.
718  **/
719 static void find_symbols_between(struct elf_info *elf, Elf_Addr addr,
720 				 const char *sec,
721 			         Elf_Sym **before, Elf_Sym **after)
722 {
723 	Elf_Sym *sym;
724 	Elf_Ehdr *hdr = elf->hdr;
725 	Elf_Addr beforediff = ~0;
726 	Elf_Addr afterdiff = ~0;
727 	const char *secstrings = (void *)hdr +
728 				 elf->sechdrs[hdr->e_shstrndx].sh_offset;
729 
730 	*before = NULL;
731 	*after = NULL;
732 
733 	for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) {
734 		const char *symsec;
735 
736 		if (sym->st_shndx >= SHN_LORESERVE)
737 			continue;
738 		symsec = secstrings + elf->sechdrs[sym->st_shndx].sh_name;
739 		if (strcmp(symsec, sec) != 0)
740 			continue;
741 		if (!is_valid_name(elf, sym))
742 			continue;
743 		if (sym->st_value <= addr) {
744 			if ((addr - sym->st_value) < beforediff) {
745 				beforediff = addr - sym->st_value;
746 				*before = sym;
747 			}
748 			else if ((addr - sym->st_value) == beforediff) {
749 				*before = sym;
750 			}
751 		}
752 		else
753 		{
754 			if ((sym->st_value - addr) < afterdiff) {
755 				afterdiff = sym->st_value - addr;
756 				*after = sym;
757 			}
758 			else if ((sym->st_value - addr) == afterdiff) {
759 				*after = sym;
760 			}
761 		}
762 	}
763 }
764 
765 /**
766  * Print a warning about a section mismatch.
767  * Try to find symbols near it so user can find it.
768  * Check whitelist before warning - it may be a false positive.
769  **/
770 static void warn_sec_mismatch(const char *modname, const char *fromsec,
771 			      struct elf_info *elf, Elf_Sym *sym, Elf_Rela r)
772 {
773 	const char *refsymname = "";
774 	Elf_Sym *before, *after;
775 	Elf_Sym *refsym;
776 	Elf_Ehdr *hdr = elf->hdr;
777 	Elf_Shdr *sechdrs = elf->sechdrs;
778 	const char *secstrings = (void *)hdr +
779 				 sechdrs[hdr->e_shstrndx].sh_offset;
780 	const char *secname = secstrings + sechdrs[sym->st_shndx].sh_name;
781 
782 	find_symbols_between(elf, r.r_offset, fromsec, &before, &after);
783 
784 	refsym = find_elf_symbol(elf, r.r_addend, sym);
785 	if (refsym && strlen(elf->strtab + refsym->st_name))
786 		refsymname = elf->strtab + refsym->st_name;
787 
788 	/* check whitelist - we may ignore it */
789 	if (before &&
790 	    secref_whitelist(modname, secname, fromsec,
791 			     elf->strtab + before->st_name, refsymname))
792 		return;
793 
794 	if (before && after) {
795 		warn("%s - Section mismatch: reference to %s:%s from %s "
796 		     "between '%s' (at offset 0x%llx) and '%s'\n",
797 		     modname, secname, refsymname, fromsec,
798 		     elf->strtab + before->st_name,
799 		     (long long)r.r_offset,
800 		     elf->strtab + after->st_name);
801 	} else if (before) {
802 		warn("%s - Section mismatch: reference to %s:%s from %s "
803 		     "after '%s' (at offset 0x%llx)\n",
804 		     modname, secname, refsymname, fromsec,
805 		     elf->strtab + before->st_name,
806 		     (long long)r.r_offset);
807 	} else if (after) {
808 		warn("%s - Section mismatch: reference to %s:%s from %s "
809 		     "before '%s' (at offset -0x%llx)\n",
810 		     modname, secname, refsymname, fromsec,
811 		     elf->strtab + after->st_name,
812 		     (long long)r.r_offset);
813 	} else {
814 		warn("%s - Section mismatch: reference to %s:%s from %s "
815 		     "(offset 0x%llx)\n",
816 		     modname, secname, fromsec, refsymname,
817 		     (long long)r.r_offset);
818 	}
819 }
820 
821 /**
822  * A module includes a number of sections that are discarded
823  * either when loaded or when used as built-in.
824  * For loaded modules all functions marked __init and all data
825  * marked __initdata will be discarded when the module has been intialized.
826  * Likewise for modules used built-in the sections marked __exit
827  * are discarded because __exit marked function are supposed to be called
828  * only when a moduel is unloaded which never happes for built-in modules.
829  * The check_sec_ref() function traverses all relocation records
830  * to find all references to a section that reference a section that will
831  * be discarded and warns about it.
832  **/
833 static void check_sec_ref(struct module *mod, const char *modname,
834 			  struct elf_info *elf,
835 			  int section(const char*),
836 			  int section_ref_ok(const char *))
837 {
838 	int i;
839 	Elf_Sym  *sym;
840 	Elf_Ehdr *hdr = elf->hdr;
841 	Elf_Shdr *sechdrs = elf->sechdrs;
842 	const char *secstrings = (void *)hdr +
843 				 sechdrs[hdr->e_shstrndx].sh_offset;
844 
845 	/* Walk through all sections */
846 	for (i = 0; i < hdr->e_shnum; i++) {
847 		const char *name = secstrings + sechdrs[i].sh_name;
848 		const char *secname;
849 		Elf_Rela r;
850 		unsigned int r_sym;
851 		/* We want to process only relocation sections and not .init */
852 		if (sechdrs[i].sh_type == SHT_RELA) {
853 			Elf_Rela *rela;
854 			Elf_Rela *start = (void *)hdr + sechdrs[i].sh_offset;
855 			Elf_Rela *stop  = (void*)start + sechdrs[i].sh_size;
856 			name += strlen(".rela");
857 			if (section_ref_ok(name))
858 				continue;
859 
860 			for (rela = start; rela < stop; rela++) {
861 				r.r_offset = TO_NATIVE(rela->r_offset);
862 #if KERNEL_ELFCLASS == ELFCLASS64
863 				if (hdr->e_machine == EM_MIPS) {
864 					r_sym = ELF64_MIPS_R_SYM(rela->r_info);
865 					r_sym = TO_NATIVE(r_sym);
866 				} else {
867 					r.r_info = TO_NATIVE(rela->r_info);
868 					r_sym = ELF_R_SYM(r.r_info);
869 				}
870 #else
871 				r.r_info = TO_NATIVE(rela->r_info);
872 				r_sym = ELF_R_SYM(r.r_info);
873 #endif
874 				r.r_addend = TO_NATIVE(rela->r_addend);
875 				sym = elf->symtab_start + r_sym;
876 				/* Skip special sections */
877 				if (sym->st_shndx >= SHN_LORESERVE)
878 					continue;
879 
880 				secname = secstrings +
881 					sechdrs[sym->st_shndx].sh_name;
882 				if (section(secname))
883 					warn_sec_mismatch(modname, name,
884 							  elf, sym, r);
885 			}
886 		} else if (sechdrs[i].sh_type == SHT_REL) {
887 			Elf_Rel *rel;
888 			Elf_Rel *start = (void *)hdr + sechdrs[i].sh_offset;
889 			Elf_Rel *stop  = (void*)start + sechdrs[i].sh_size;
890 			name += strlen(".rel");
891 			if (section_ref_ok(name))
892 				continue;
893 
894 			for (rel = start; rel < stop; rel++) {
895 				r.r_offset = TO_NATIVE(rel->r_offset);
896 #if KERNEL_ELFCLASS == ELFCLASS64
897 				if (hdr->e_machine == EM_MIPS) {
898 					r_sym = ELF64_MIPS_R_SYM(rel->r_info);
899 					r_sym = TO_NATIVE(r_sym);
900 				} else {
901 					r.r_info = TO_NATIVE(rel->r_info);
902 					r_sym = ELF_R_SYM(r.r_info);
903 				}
904 #else
905 				r.r_info = TO_NATIVE(rel->r_info);
906 				r_sym = ELF_R_SYM(r.r_info);
907 #endif
908 				r.r_addend = 0;
909 				sym = elf->symtab_start + r_sym;
910 				/* Skip special sections */
911 				if (sym->st_shndx >= SHN_LORESERVE)
912 					continue;
913 
914 				secname = secstrings +
915 					sechdrs[sym->st_shndx].sh_name;
916 				if (section(secname))
917 					warn_sec_mismatch(modname, name,
918 							  elf, sym, r);
919 			}
920 		}
921 	}
922 }
923 
924 /**
925  * Functions used only during module init is marked __init and is stored in
926  * a .init.text section. Likewise data is marked __initdata and stored in
927  * a .init.data section.
928  * If this section is one of these sections return 1
929  * See include/linux/init.h for the details
930  **/
931 static int init_section(const char *name)
932 {
933 	if (strcmp(name, ".init") == 0)
934 		return 1;
935 	if (strncmp(name, ".init.", strlen(".init.")) == 0)
936 		return 1;
937 	return 0;
938 }
939 
940 /**
941  * Identify sections from which references to a .init section is OK.
942  *
943  * Unfortunately references to read only data that referenced .init
944  * sections had to be excluded. Almost all of these are false
945  * positives, they are created by gcc. The downside of excluding rodata
946  * is that there really are some user references from rodata to
947  * init code, e.g. drivers/video/vgacon.c:
948  *
949  * const struct consw vga_con = {
950  *        con_startup:            vgacon_startup,
951  *
952  * where vgacon_startup is __init.  If you want to wade through the false
953  * positives, take out the check for rodata.
954  **/
955 static int init_section_ref_ok(const char *name)
956 {
957 	const char **s;
958 	/* Absolute section names */
959 	const char *namelist1[] = {
960 		".init",
961 		".opd",   /* see comment [OPD] at exit_section_ref_ok() */
962 		".toc1",  /* used by ppc64 */
963 		".stab",
964 		".data.rel.ro", /* used by parisc64 */
965 		".parainstructions",
966 		".text.lock",
967 		"__bug_table", /* used by powerpc for BUG() */
968 		".pci_fixup_header",
969 		".pci_fixup_final",
970 		".pdr",
971 		"__param",
972 		"__ex_table",
973 		".fixup",
974 		".smp_locks",
975 		".plt",  /* seen on ARCH=um build on x86_64. Harmless */
976 		"__ftr_fixup",		/* powerpc cpu feature fixup */
977 		"__fw_ftr_fixup",	/* powerpc firmware feature fixup */
978 		NULL
979 	};
980 	/* Start of section names */
981 	const char *namelist2[] = {
982 		".init.",
983 		".altinstructions",
984 		".eh_frame",
985 		".debug",
986 		".parainstructions",
987 		".rodata",
988 		NULL
989 	};
990 	/* part of section name */
991 	const char *namelist3 [] = {
992 		".unwind",  /* sample: IA_64.unwind.init.text */
993 		NULL
994 	};
995 
996 	for (s = namelist1; *s; s++)
997 		if (strcmp(*s, name) == 0)
998 			return 1;
999 	for (s = namelist2; *s; s++)
1000 		if (strncmp(*s, name, strlen(*s)) == 0)
1001 			return 1;
1002 	for (s = namelist3; *s; s++)
1003 		if (strstr(name, *s) != NULL)
1004 			return 1;
1005 	if (strrcmp(name, ".init") == 0)
1006 		return 1;
1007 	return 0;
1008 }
1009 
1010 /*
1011  * Functions used only during module exit is marked __exit and is stored in
1012  * a .exit.text section. Likewise data is marked __exitdata and stored in
1013  * a .exit.data section.
1014  * If this section is one of these sections return 1
1015  * See include/linux/init.h for the details
1016  **/
1017 static int exit_section(const char *name)
1018 {
1019 	if (strcmp(name, ".exit.text") == 0)
1020 		return 1;
1021 	if (strcmp(name, ".exit.data") == 0)
1022 		return 1;
1023 	return 0;
1024 
1025 }
1026 
1027 /*
1028  * Identify sections from which references to a .exit section is OK.
1029  *
1030  * [OPD] Keith Ownes <kaos@sgi.com> commented:
1031  * For our future {in}sanity, add a comment that this is the ppc .opd
1032  * section, not the ia64 .opd section.
1033  * ia64 .opd should not point to discarded sections.
1034  * [.rodata] like for .init.text we ignore .rodata references -same reason
1035  **/
1036 static int exit_section_ref_ok(const char *name)
1037 {
1038 	const char **s;
1039 	/* Absolute section names */
1040 	const char *namelist1[] = {
1041 		".exit.text",
1042 		".exit.data",
1043 		".init.text",
1044 		".rodata",
1045 		".opd", /* See comment [OPD] */
1046 		".toc1",  /* used by ppc64 */
1047 		".altinstructions",
1048 		".pdr",
1049 		"__bug_table", /* used by powerpc for BUG() */
1050 		".exitcall.exit",
1051 		".eh_frame",
1052 		".parainstructions",
1053 		".stab",
1054 		"__ex_table",
1055 		".fixup",
1056 		".smp_locks",
1057 		".plt",  /* seen on ARCH=um build on x86_64. Harmless */
1058 		NULL
1059 	};
1060 	/* Start of section names */
1061 	const char *namelist2[] = {
1062 		".debug",
1063 		NULL
1064 	};
1065 	/* part of section name */
1066 	const char *namelist3 [] = {
1067 		".unwind",  /* Sample: IA_64.unwind.exit.text */
1068 		NULL
1069 	};
1070 
1071 	for (s = namelist1; *s; s++)
1072 		if (strcmp(*s, name) == 0)
1073 			return 1;
1074 	for (s = namelist2; *s; s++)
1075 		if (strncmp(*s, name, strlen(*s)) == 0)
1076 			return 1;
1077 	for (s = namelist3; *s; s++)
1078 		if (strstr(name, *s) != NULL)
1079 			return 1;
1080 	return 0;
1081 }
1082 
1083 static void read_symbols(char *modname)
1084 {
1085 	const char *symname;
1086 	char *version;
1087 	char *license;
1088 	struct module *mod;
1089 	struct elf_info info = { };
1090 	Elf_Sym *sym;
1091 
1092 	parse_elf(&info, modname);
1093 
1094 	mod = new_module(modname);
1095 
1096 	/* When there's no vmlinux, don't print warnings about
1097 	 * unresolved symbols (since there'll be too many ;) */
1098 	if (is_vmlinux(modname)) {
1099 		have_vmlinux = 1;
1100 		mod->skip = 1;
1101 	}
1102 
1103 	license = get_modinfo(info.modinfo, info.modinfo_len, "license");
1104 	while (license) {
1105 		if (license_is_gpl_compatible(license))
1106 			mod->gpl_compatible = 1;
1107 		else {
1108 			mod->gpl_compatible = 0;
1109 			break;
1110 		}
1111 		license = get_next_modinfo(info.modinfo, info.modinfo_len,
1112 					   "license", license);
1113 	}
1114 
1115 	for (sym = info.symtab_start; sym < info.symtab_stop; sym++) {
1116 		symname = info.strtab + sym->st_name;
1117 
1118 		handle_modversions(mod, &info, sym, symname);
1119 		handle_moddevtable(mod, &info, sym, symname);
1120 	}
1121 	check_sec_ref(mod, modname, &info, init_section, init_section_ref_ok);
1122 	check_sec_ref(mod, modname, &info, exit_section, exit_section_ref_ok);
1123 
1124 	version = get_modinfo(info.modinfo, info.modinfo_len, "version");
1125 	if (version)
1126 		maybe_frob_rcs_version(modname, version, info.modinfo,
1127 				       version - (char *)info.hdr);
1128 	if (version || (all_versions && !is_vmlinux(modname)))
1129 		get_src_version(modname, mod->srcversion,
1130 				sizeof(mod->srcversion)-1);
1131 
1132 	parse_elf_finish(&info);
1133 
1134 	/* Our trick to get versioning for struct_module - it's
1135 	 * never passed as an argument to an exported function, so
1136 	 * the automatic versioning doesn't pick it up, but it's really
1137 	 * important anyhow */
1138 	if (modversions)
1139 		mod->unres = alloc_symbol("struct_module", 0, mod->unres);
1140 }
1141 
1142 #define SZ 500
1143 
1144 /* We first write the generated file into memory using the
1145  * following helper, then compare to the file on disk and
1146  * only update the later if anything changed */
1147 
1148 void __attribute__((format(printf, 2, 3))) buf_printf(struct buffer *buf,
1149 						      const char *fmt, ...)
1150 {
1151 	char tmp[SZ];
1152 	int len;
1153 	va_list ap;
1154 
1155 	va_start(ap, fmt);
1156 	len = vsnprintf(tmp, SZ, fmt, ap);
1157 	buf_write(buf, tmp, len);
1158 	va_end(ap);
1159 }
1160 
1161 void buf_write(struct buffer *buf, const char *s, int len)
1162 {
1163 	if (buf->size - buf->pos < len) {
1164 		buf->size += len + SZ;
1165 		buf->p = realloc(buf->p, buf->size);
1166 	}
1167 	strncpy(buf->p + buf->pos, s, len);
1168 	buf->pos += len;
1169 }
1170 
1171 static void check_for_gpl_usage(enum export exp, const char *m, const char *s)
1172 {
1173 	const char *e = is_vmlinux(m) ?"":".ko";
1174 
1175 	switch (exp) {
1176 	case export_gpl:
1177 		fatal("modpost: GPL-incompatible module %s%s "
1178 		      "uses GPL-only symbol '%s'\n", m, e, s);
1179 		break;
1180 	case export_unused_gpl:
1181 		fatal("modpost: GPL-incompatible module %s%s "
1182 		      "uses GPL-only symbol marked UNUSED '%s'\n", m, e, s);
1183 		break;
1184 	case export_gpl_future:
1185 		warn("modpost: GPL-incompatible module %s%s "
1186 		      "uses future GPL-only symbol '%s'\n", m, e, s);
1187 		break;
1188 	case export_plain:
1189 	case export_unused:
1190 	case export_unknown:
1191 		/* ignore */
1192 		break;
1193 	}
1194 }
1195 
1196 static void check_for_unused(enum export exp, const char* m, const char* s)
1197 {
1198 	const char *e = is_vmlinux(m) ?"":".ko";
1199 
1200 	switch (exp) {
1201 	case export_unused:
1202 	case export_unused_gpl:
1203 		warn("modpost: module %s%s "
1204 		      "uses symbol '%s' marked UNUSED\n", m, e, s);
1205 		break;
1206 	default:
1207 		/* ignore */
1208 		break;
1209 	}
1210 }
1211 
1212 static void check_exports(struct module *mod)
1213 {
1214 	struct symbol *s, *exp;
1215 
1216 	for (s = mod->unres; s; s = s->next) {
1217 		const char *basename;
1218 		exp = find_symbol(s->name);
1219 		if (!exp || exp->module == mod)
1220 			continue;
1221 		basename = strrchr(mod->name, '/');
1222 		if (basename)
1223 			basename++;
1224 		else
1225 			basename = mod->name;
1226 		if (!mod->gpl_compatible)
1227 			check_for_gpl_usage(exp->export, basename, exp->name);
1228 		check_for_unused(exp->export, basename, exp->name);
1229         }
1230 }
1231 
1232 /**
1233  * Header for the generated file
1234  **/
1235 static void add_header(struct buffer *b, struct module *mod)
1236 {
1237 	buf_printf(b, "#include <linux/module.h>\n");
1238 	buf_printf(b, "#include <linux/vermagic.h>\n");
1239 	buf_printf(b, "#include <linux/compiler.h>\n");
1240 	buf_printf(b, "\n");
1241 	buf_printf(b, "MODULE_INFO(vermagic, VERMAGIC_STRING);\n");
1242 	buf_printf(b, "\n");
1243 	buf_printf(b, "struct module __this_module\n");
1244 	buf_printf(b, "__attribute__((section(\".gnu.linkonce.this_module\"))) = {\n");
1245 	buf_printf(b, " .name = KBUILD_MODNAME,\n");
1246 	if (mod->has_init)
1247 		buf_printf(b, " .init = init_module,\n");
1248 	if (mod->has_cleanup)
1249 		buf_printf(b, "#ifdef CONFIG_MODULE_UNLOAD\n"
1250 			      " .exit = cleanup_module,\n"
1251 			      "#endif\n");
1252 	buf_printf(b, "};\n");
1253 }
1254 
1255 /**
1256  * Record CRCs for unresolved symbols
1257  **/
1258 static int add_versions(struct buffer *b, struct module *mod)
1259 {
1260 	struct symbol *s, *exp;
1261 	int err = 0;
1262 
1263 	for (s = mod->unres; s; s = s->next) {
1264 		exp = find_symbol(s->name);
1265 		if (!exp || exp->module == mod) {
1266 			if (have_vmlinux && !s->weak) {
1267 				warn("\"%s\" [%s.ko] undefined!\n",
1268 				     s->name, mod->name);
1269 				err = warn_unresolved ? 0 : 1;
1270 			}
1271 			continue;
1272 		}
1273 		s->module = exp->module;
1274 		s->crc_valid = exp->crc_valid;
1275 		s->crc = exp->crc;
1276 	}
1277 
1278 	if (!modversions)
1279 		return err;
1280 
1281 	buf_printf(b, "\n");
1282 	buf_printf(b, "static const struct modversion_info ____versions[]\n");
1283 	buf_printf(b, "__attribute_used__\n");
1284 	buf_printf(b, "__attribute__((section(\"__versions\"))) = {\n");
1285 
1286 	for (s = mod->unres; s; s = s->next) {
1287 		if (!s->module) {
1288 			continue;
1289 		}
1290 		if (!s->crc_valid) {
1291 			warn("\"%s\" [%s.ko] has no CRC!\n",
1292 				s->name, mod->name);
1293 			continue;
1294 		}
1295 		buf_printf(b, "\t{ %#8x, \"%s\" },\n", s->crc, s->name);
1296 	}
1297 
1298 	buf_printf(b, "};\n");
1299 
1300 	return err;
1301 }
1302 
1303 static void add_depends(struct buffer *b, struct module *mod,
1304 			struct module *modules)
1305 {
1306 	struct symbol *s;
1307 	struct module *m;
1308 	int first = 1;
1309 
1310 	for (m = modules; m; m = m->next) {
1311 		m->seen = is_vmlinux(m->name);
1312 	}
1313 
1314 	buf_printf(b, "\n");
1315 	buf_printf(b, "static const char __module_depends[]\n");
1316 	buf_printf(b, "__attribute_used__\n");
1317 	buf_printf(b, "__attribute__((section(\".modinfo\"))) =\n");
1318 	buf_printf(b, "\"depends=");
1319 	for (s = mod->unres; s; s = s->next) {
1320 		if (!s->module)
1321 			continue;
1322 
1323 		if (s->module->seen)
1324 			continue;
1325 
1326 		s->module->seen = 1;
1327 		buf_printf(b, "%s%s", first ? "" : ",",
1328 			   strrchr(s->module->name, '/') + 1);
1329 		first = 0;
1330 	}
1331 	buf_printf(b, "\";\n");
1332 }
1333 
1334 static void add_srcversion(struct buffer *b, struct module *mod)
1335 {
1336 	if (mod->srcversion[0]) {
1337 		buf_printf(b, "\n");
1338 		buf_printf(b, "MODULE_INFO(srcversion, \"%s\");\n",
1339 			   mod->srcversion);
1340 	}
1341 }
1342 
1343 static void write_if_changed(struct buffer *b, const char *fname)
1344 {
1345 	char *tmp;
1346 	FILE *file;
1347 	struct stat st;
1348 
1349 	file = fopen(fname, "r");
1350 	if (!file)
1351 		goto write;
1352 
1353 	if (fstat(fileno(file), &st) < 0)
1354 		goto close_write;
1355 
1356 	if (st.st_size != b->pos)
1357 		goto close_write;
1358 
1359 	tmp = NOFAIL(malloc(b->pos));
1360 	if (fread(tmp, 1, b->pos, file) != b->pos)
1361 		goto free_write;
1362 
1363 	if (memcmp(tmp, b->p, b->pos) != 0)
1364 		goto free_write;
1365 
1366 	free(tmp);
1367 	fclose(file);
1368 	return;
1369 
1370  free_write:
1371 	free(tmp);
1372  close_write:
1373 	fclose(file);
1374  write:
1375 	file = fopen(fname, "w");
1376 	if (!file) {
1377 		perror(fname);
1378 		exit(1);
1379 	}
1380 	if (fwrite(b->p, 1, b->pos, file) != b->pos) {
1381 		perror(fname);
1382 		exit(1);
1383 	}
1384 	fclose(file);
1385 }
1386 
1387 /* parse Module.symvers file. line format:
1388  * 0x12345678<tab>symbol<tab>module[[<tab>export]<tab>something]
1389  **/
1390 static void read_dump(const char *fname, unsigned int kernel)
1391 {
1392 	unsigned long size, pos = 0;
1393 	void *file = grab_file(fname, &size);
1394 	char *line;
1395 
1396         if (!file)
1397 		/* No symbol versions, silently ignore */
1398 		return;
1399 
1400 	while ((line = get_next_line(&pos, file, size))) {
1401 		char *symname, *modname, *d, *export, *end;
1402 		unsigned int crc;
1403 		struct module *mod;
1404 		struct symbol *s;
1405 
1406 		if (!(symname = strchr(line, '\t')))
1407 			goto fail;
1408 		*symname++ = '\0';
1409 		if (!(modname = strchr(symname, '\t')))
1410 			goto fail;
1411 		*modname++ = '\0';
1412 		if ((export = strchr(modname, '\t')) != NULL)
1413 			*export++ = '\0';
1414 		if (export && ((end = strchr(export, '\t')) != NULL))
1415 			*end = '\0';
1416 		crc = strtoul(line, &d, 16);
1417 		if (*symname == '\0' || *modname == '\0' || *d != '\0')
1418 			goto fail;
1419 
1420 		if (!(mod = find_module(modname))) {
1421 			if (is_vmlinux(modname)) {
1422 				have_vmlinux = 1;
1423 			}
1424 			mod = new_module(NOFAIL(strdup(modname)));
1425 			mod->skip = 1;
1426 		}
1427 		s = sym_add_exported(symname, mod, export_no(export));
1428 		s->kernel    = kernel;
1429 		s->preloaded = 1;
1430 		sym_update_crc(symname, mod, crc, export_no(export));
1431 	}
1432 	return;
1433 fail:
1434 	fatal("parse error in symbol dump file\n");
1435 }
1436 
1437 /* For normal builds always dump all symbols.
1438  * For external modules only dump symbols
1439  * that are not read from kernel Module.symvers.
1440  **/
1441 static int dump_sym(struct symbol *sym)
1442 {
1443 	if (!external_module)
1444 		return 1;
1445 	if (sym->vmlinux || sym->kernel)
1446 		return 0;
1447 	return 1;
1448 }
1449 
1450 static void write_dump(const char *fname)
1451 {
1452 	struct buffer buf = { };
1453 	struct symbol *symbol;
1454 	int n;
1455 
1456 	for (n = 0; n < SYMBOL_HASH_SIZE ; n++) {
1457 		symbol = symbolhash[n];
1458 		while (symbol) {
1459 			if (dump_sym(symbol))
1460 				buf_printf(&buf, "0x%08x\t%s\t%s\t%s\n",
1461 					symbol->crc, symbol->name,
1462 					symbol->module->name,
1463 					export_str(symbol->export));
1464 			symbol = symbol->next;
1465 		}
1466 	}
1467 	write_if_changed(&buf, fname);
1468 }
1469 
1470 int main(int argc, char **argv)
1471 {
1472 	struct module *mod;
1473 	struct buffer buf = { };
1474 	char fname[SZ];
1475 	char *kernel_read = NULL, *module_read = NULL;
1476 	char *dump_write = NULL;
1477 	int opt;
1478 	int err;
1479 
1480 	while ((opt = getopt(argc, argv, "i:I:mo:aw")) != -1) {
1481 		switch(opt) {
1482 			case 'i':
1483 				kernel_read = optarg;
1484 				break;
1485 			case 'I':
1486 				module_read = optarg;
1487 				external_module = 1;
1488 				break;
1489 			case 'm':
1490 				modversions = 1;
1491 				break;
1492 			case 'o':
1493 				dump_write = optarg;
1494 				break;
1495 			case 'a':
1496 				all_versions = 1;
1497 				break;
1498 			case 'w':
1499 				warn_unresolved = 1;
1500 				break;
1501 			default:
1502 				exit(1);
1503 		}
1504 	}
1505 
1506 	if (kernel_read)
1507 		read_dump(kernel_read, 1);
1508 	if (module_read)
1509 		read_dump(module_read, 0);
1510 
1511 	while (optind < argc) {
1512 		read_symbols(argv[optind++]);
1513 	}
1514 
1515 	for (mod = modules; mod; mod = mod->next) {
1516 		if (mod->skip)
1517 			continue;
1518 		check_exports(mod);
1519 	}
1520 
1521 	err = 0;
1522 
1523 	for (mod = modules; mod; mod = mod->next) {
1524 		if (mod->skip)
1525 			continue;
1526 
1527 		buf.pos = 0;
1528 
1529 		add_header(&buf, mod);
1530 		err |= add_versions(&buf, mod);
1531 		add_depends(&buf, mod, modules);
1532 		add_moddevtable(&buf, mod);
1533 		add_srcversion(&buf, mod);
1534 
1535 		sprintf(fname, "%s.mod.c", mod->name);
1536 		write_if_changed(&buf, fname);
1537 	}
1538 
1539 	if (dump_write)
1540 		write_dump(dump_write);
1541 
1542 	return err;
1543 }
1544