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TOMOYO Linux Cross Reference
Linux/scripts/mod/modpost.c

Version: ~ [ linux-5.15-rc7 ] ~ [ linux-5.14.14 ] ~ [ linux-5.13.19 ] ~ [ linux-5.12.19 ] ~ [ linux-5.11.22 ] ~ [ linux-5.10.75 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.155 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.213 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.252 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.287 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.289 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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  1 /* Postprocess module symbol versions
  2  *
  3  * Copyright 2003       Kai Germaschewski
  4  * Copyright 2002-2004  Rusty Russell, IBM Corporation
  5  * Copyright 2006-2008  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 #define _GNU_SOURCE
 15 #include <stdio.h>
 16 #include <ctype.h>
 17 #include <string.h>
 18 #include <limits.h>
 19 #include <stdbool.h>
 20 #include <errno.h>
 21 #include "modpost.h"
 22 #include "../../include/generated/autoconf.h"
 23 #include "../../include/linux/license.h"
 24 #include "../../include/linux/export.h"
 25 
 26 /* Are we using CONFIG_MODVERSIONS? */
 27 static int modversions = 0;
 28 /* Warn about undefined symbols? (do so if we have vmlinux) */
 29 static int have_vmlinux = 0;
 30 /* Is CONFIG_MODULE_SRCVERSION_ALL set? */
 31 static int all_versions = 0;
 32 /* If we are modposting external module set to 1 */
 33 static int external_module = 0;
 34 /* Warn about section mismatch in vmlinux if set to 1 */
 35 static int vmlinux_section_warnings = 1;
 36 /* Only warn about unresolved symbols */
 37 static int warn_unresolved = 0;
 38 /* How a symbol is exported */
 39 static int sec_mismatch_count = 0;
 40 static int sec_mismatch_verbose = 1;
 41 static int sec_mismatch_fatal = 0;
 42 /* ignore missing files */
 43 static int ignore_missing_files;
 44 
 45 enum export {
 46         export_plain,      export_unused,     export_gpl,
 47         export_unused_gpl, export_gpl_future, export_unknown
 48 };
 49 
 50 #define PRINTF __attribute__ ((format (printf, 1, 2)))
 51 
 52 PRINTF void fatal(const char *fmt, ...)
 53 {
 54         va_list arglist;
 55 
 56         fprintf(stderr, "FATAL: ");
 57 
 58         va_start(arglist, fmt);
 59         vfprintf(stderr, fmt, arglist);
 60         va_end(arglist);
 61 
 62         exit(1);
 63 }
 64 
 65 PRINTF void warn(const char *fmt, ...)
 66 {
 67         va_list arglist;
 68 
 69         fprintf(stderr, "WARNING: ");
 70 
 71         va_start(arglist, fmt);
 72         vfprintf(stderr, fmt, arglist);
 73         va_end(arglist);
 74 }
 75 
 76 PRINTF void merror(const char *fmt, ...)
 77 {
 78         va_list arglist;
 79 
 80         fprintf(stderr, "ERROR: ");
 81 
 82         va_start(arglist, fmt);
 83         vfprintf(stderr, fmt, arglist);
 84         va_end(arglist);
 85 }
 86 
 87 static inline bool strends(const char *str, const char *postfix)
 88 {
 89         if (strlen(str) < strlen(postfix))
 90                 return false;
 91 
 92         return strcmp(str + strlen(str) - strlen(postfix), postfix) == 0;
 93 }
 94 
 95 static int is_vmlinux(const char *modname)
 96 {
 97         const char *myname;
 98 
 99         myname = strrchr(modname, '/');
100         if (myname)
101                 myname++;
102         else
103                 myname = modname;
104 
105         return (strcmp(myname, "vmlinux") == 0) ||
106                (strcmp(myname, "vmlinux.o") == 0);
107 }
108 
109 void *do_nofail(void *ptr, const char *expr)
110 {
111         if (!ptr)
112                 fatal("modpost: Memory allocation failure: %s.\n", expr);
113 
114         return ptr;
115 }
116 
117 /* A list of all modules we processed */
118 static struct module *modules;
119 
120 static struct module *find_module(char *modname)
121 {
122         struct module *mod;
123 
124         for (mod = modules; mod; mod = mod->next)
125                 if (strcmp(mod->name, modname) == 0)
126                         break;
127         return mod;
128 }
129 
130 static struct module *new_module(const char *modname)
131 {
132         struct module *mod;
133         char *p;
134 
135         mod = NOFAIL(malloc(sizeof(*mod)));
136         memset(mod, 0, sizeof(*mod));
137         p = NOFAIL(strdup(modname));
138 
139         /* strip trailing .o */
140         if (strends(p, ".o")) {
141                 p[strlen(p) - 2] = '\0';
142                 mod->is_dot_o = 1;
143         }
144 
145         /* add to list */
146         mod->name = p;
147         mod->gpl_compatible = -1;
148         mod->next = modules;
149         modules = mod;
150 
151         return mod;
152 }
153 
154 /* A hash of all exported symbols,
155  * struct symbol is also used for lists of unresolved symbols */
156 
157 #define SYMBOL_HASH_SIZE 1024
158 
159 struct symbol {
160         struct symbol *next;
161         struct module *module;
162         unsigned int crc;
163         int crc_valid;
164         unsigned int weak:1;
165         unsigned int vmlinux:1;    /* 1 if symbol is defined in vmlinux */
166         unsigned int kernel:1;     /* 1 if symbol is from kernel
167                                     *  (only for external modules) **/
168         unsigned int preloaded:1;  /* 1 if symbol from Module.symvers, or crc */
169         enum export  export;       /* Type of export */
170         char name[0];
171 };
172 
173 static struct symbol *symbolhash[SYMBOL_HASH_SIZE];
174 
175 /* This is based on the hash agorithm from gdbm, via tdb */
176 static inline unsigned int tdb_hash(const char *name)
177 {
178         unsigned value; /* Used to compute the hash value.  */
179         unsigned   i;   /* Used to cycle through random values. */
180 
181         /* Set the initial value from the key size. */
182         for (value = 0x238F13AF * strlen(name), i = 0; name[i]; i++)
183                 value = (value + (((unsigned char *)name)[i] << (i*5 % 24)));
184 
185         return (1103515243 * value + 12345);
186 }
187 
188 /**
189  * Allocate a new symbols for use in the hash of exported symbols or
190  * the list of unresolved symbols per module
191  **/
192 static struct symbol *alloc_symbol(const char *name, unsigned int weak,
193                                    struct symbol *next)
194 {
195         struct symbol *s = NOFAIL(malloc(sizeof(*s) + strlen(name) + 1));
196 
197         memset(s, 0, sizeof(*s));
198         strcpy(s->name, name);
199         s->weak = weak;
200         s->next = next;
201         return s;
202 }
203 
204 /* For the hash of exported symbols */
205 static struct symbol *new_symbol(const char *name, struct module *module,
206                                  enum export export)
207 {
208         unsigned int hash;
209         struct symbol *new;
210 
211         hash = tdb_hash(name) % SYMBOL_HASH_SIZE;
212         new = symbolhash[hash] = alloc_symbol(name, 0, symbolhash[hash]);
213         new->module = module;
214         new->export = export;
215         return new;
216 }
217 
218 static struct symbol *find_symbol(const char *name)
219 {
220         struct symbol *s;
221 
222         /* For our purposes, .foo matches foo.  PPC64 needs this. */
223         if (name[0] == '.')
224                 name++;
225 
226         for (s = symbolhash[tdb_hash(name) % SYMBOL_HASH_SIZE]; s; s = s->next) {
227                 if (strcmp(s->name, name) == 0)
228                         return s;
229         }
230         return NULL;
231 }
232 
233 static const struct {
234         const char *str;
235         enum export export;
236 } export_list[] = {
237         { .str = "EXPORT_SYMBOL",            .export = export_plain },
238         { .str = "EXPORT_UNUSED_SYMBOL",     .export = export_unused },
239         { .str = "EXPORT_SYMBOL_GPL",        .export = export_gpl },
240         { .str = "EXPORT_UNUSED_SYMBOL_GPL", .export = export_unused_gpl },
241         { .str = "EXPORT_SYMBOL_GPL_FUTURE", .export = export_gpl_future },
242         { .str = "(unknown)",                .export = export_unknown },
243 };
244 
245 
246 static const char *export_str(enum export ex)
247 {
248         return export_list[ex].str;
249 }
250 
251 static enum export export_no(const char *s)
252 {
253         int i;
254 
255         if (!s)
256                 return export_unknown;
257         for (i = 0; export_list[i].export != export_unknown; i++) {
258                 if (strcmp(export_list[i].str, s) == 0)
259                         return export_list[i].export;
260         }
261         return export_unknown;
262 }
263 
264 static const char *sec_name(struct elf_info *elf, int secindex);
265 
266 #define strstarts(str, prefix) (strncmp(str, prefix, strlen(prefix)) == 0)
267 
268 static enum export export_from_secname(struct elf_info *elf, unsigned int sec)
269 {
270         const char *secname = sec_name(elf, sec);
271 
272         if (strstarts(secname, "___ksymtab+"))
273                 return export_plain;
274         else if (strstarts(secname, "___ksymtab_unused+"))
275                 return export_unused;
276         else if (strstarts(secname, "___ksymtab_gpl+"))
277                 return export_gpl;
278         else if (strstarts(secname, "___ksymtab_unused_gpl+"))
279                 return export_unused_gpl;
280         else if (strstarts(secname, "___ksymtab_gpl_future+"))
281                 return export_gpl_future;
282         else
283                 return export_unknown;
284 }
285 
286 static enum export export_from_sec(struct elf_info *elf, unsigned int sec)
287 {
288         if (sec == elf->export_sec)
289                 return export_plain;
290         else if (sec == elf->export_unused_sec)
291                 return export_unused;
292         else if (sec == elf->export_gpl_sec)
293                 return export_gpl;
294         else if (sec == elf->export_unused_gpl_sec)
295                 return export_unused_gpl;
296         else if (sec == elf->export_gpl_future_sec)
297                 return export_gpl_future;
298         else
299                 return export_unknown;
300 }
301 
302 /**
303  * Add an exported symbol - it may have already been added without a
304  * CRC, in this case just update the CRC
305  **/
306 static struct symbol *sym_add_exported(const char *name, struct module *mod,
307                                        enum export export)
308 {
309         struct symbol *s = find_symbol(name);
310 
311         if (!s) {
312                 s = new_symbol(name, mod, export);
313         } else {
314                 if (!s->preloaded) {
315                         warn("%s: '%s' exported twice. Previous export "
316                              "was in %s%s\n", mod->name, name,
317                              s->module->name,
318                              is_vmlinux(s->module->name) ?"":".ko");
319                 } else {
320                         /* In case Module.symvers was out of date */
321                         s->module = mod;
322                 }
323         }
324         s->preloaded = 0;
325         s->vmlinux   = is_vmlinux(mod->name);
326         s->kernel    = 0;
327         s->export    = export;
328         return s;
329 }
330 
331 static void sym_update_crc(const char *name, struct module *mod,
332                            unsigned int crc, enum export export)
333 {
334         struct symbol *s = find_symbol(name);
335 
336         if (!s) {
337                 s = new_symbol(name, mod, export);
338                 /* Don't complain when we find it later. */
339                 s->preloaded = 1;
340         }
341         s->crc = crc;
342         s->crc_valid = 1;
343 }
344 
345 void *grab_file(const char *filename, unsigned long *size)
346 {
347         struct stat st;
348         void *map = MAP_FAILED;
349         int fd;
350 
351         fd = open(filename, O_RDONLY);
352         if (fd < 0)
353                 return NULL;
354         if (fstat(fd, &st))
355                 goto failed;
356 
357         *size = st.st_size;
358         map = mmap(NULL, *size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
359 
360 failed:
361         close(fd);
362         if (map == MAP_FAILED)
363                 return NULL;
364         return map;
365 }
366 
367 /**
368   * Return a copy of the next line in a mmap'ed file.
369   * spaces in the beginning of the line is trimmed away.
370   * Return a pointer to a static buffer.
371   **/
372 char *get_next_line(unsigned long *pos, void *file, unsigned long size)
373 {
374         static char line[4096];
375         int skip = 1;
376         size_t len = 0;
377         signed char *p = (signed char *)file + *pos;
378         char *s = line;
379 
380         for (; *pos < size ; (*pos)++) {
381                 if (skip && isspace(*p)) {
382                         p++;
383                         continue;
384                 }
385                 skip = 0;
386                 if (*p != '\n' && (*pos < size)) {
387                         len++;
388                         *s++ = *p++;
389                         if (len > 4095)
390                                 break; /* Too long, stop */
391                 } else {
392                         /* End of string */
393                         *s = '\0';
394                         return line;
395                 }
396         }
397         /* End of buffer */
398         return NULL;
399 }
400 
401 void release_file(void *file, unsigned long size)
402 {
403         munmap(file, size);
404 }
405 
406 static int parse_elf(struct elf_info *info, const char *filename)
407 {
408         unsigned int i;
409         Elf_Ehdr *hdr;
410         Elf_Shdr *sechdrs;
411         Elf_Sym  *sym;
412         const char *secstrings;
413         unsigned int symtab_idx = ~0U, symtab_shndx_idx = ~0U;
414 
415         hdr = grab_file(filename, &info->size);
416         if (!hdr) {
417                 if (ignore_missing_files) {
418                         fprintf(stderr, "%s: %s (ignored)\n", filename,
419                                 strerror(errno));
420                         return 0;
421                 }
422                 perror(filename);
423                 exit(1);
424         }
425         info->hdr = hdr;
426         if (info->size < sizeof(*hdr)) {
427                 /* file too small, assume this is an empty .o file */
428                 return 0;
429         }
430         /* Is this a valid ELF file? */
431         if ((hdr->e_ident[EI_MAG0] != ELFMAG0) ||
432             (hdr->e_ident[EI_MAG1] != ELFMAG1) ||
433             (hdr->e_ident[EI_MAG2] != ELFMAG2) ||
434             (hdr->e_ident[EI_MAG3] != ELFMAG3)) {
435                 /* Not an ELF file - silently ignore it */
436                 return 0;
437         }
438         /* Fix endianness in ELF header */
439         hdr->e_type      = TO_NATIVE(hdr->e_type);
440         hdr->e_machine   = TO_NATIVE(hdr->e_machine);
441         hdr->e_version   = TO_NATIVE(hdr->e_version);
442         hdr->e_entry     = TO_NATIVE(hdr->e_entry);
443         hdr->e_phoff     = TO_NATIVE(hdr->e_phoff);
444         hdr->e_shoff     = TO_NATIVE(hdr->e_shoff);
445         hdr->e_flags     = TO_NATIVE(hdr->e_flags);
446         hdr->e_ehsize    = TO_NATIVE(hdr->e_ehsize);
447         hdr->e_phentsize = TO_NATIVE(hdr->e_phentsize);
448         hdr->e_phnum     = TO_NATIVE(hdr->e_phnum);
449         hdr->e_shentsize = TO_NATIVE(hdr->e_shentsize);
450         hdr->e_shnum     = TO_NATIVE(hdr->e_shnum);
451         hdr->e_shstrndx  = TO_NATIVE(hdr->e_shstrndx);
452         sechdrs = (void *)hdr + hdr->e_shoff;
453         info->sechdrs = sechdrs;
454 
455         /* Check if file offset is correct */
456         if (hdr->e_shoff > info->size) {
457                 fatal("section header offset=%lu in file '%s' is bigger than "
458                       "filesize=%lu\n", (unsigned long)hdr->e_shoff,
459                       filename, info->size);
460                 return 0;
461         }
462 
463         if (hdr->e_shnum == SHN_UNDEF) {
464                 /*
465                  * There are more than 64k sections,
466                  * read count from .sh_size.
467                  */
468                 info->num_sections = TO_NATIVE(sechdrs[0].sh_size);
469         }
470         else {
471                 info->num_sections = hdr->e_shnum;
472         }
473         if (hdr->e_shstrndx == SHN_XINDEX) {
474                 info->secindex_strings = TO_NATIVE(sechdrs[0].sh_link);
475         }
476         else {
477                 info->secindex_strings = hdr->e_shstrndx;
478         }
479 
480         /* Fix endianness in section headers */
481         for (i = 0; i < info->num_sections; i++) {
482                 sechdrs[i].sh_name      = TO_NATIVE(sechdrs[i].sh_name);
483                 sechdrs[i].sh_type      = TO_NATIVE(sechdrs[i].sh_type);
484                 sechdrs[i].sh_flags     = TO_NATIVE(sechdrs[i].sh_flags);
485                 sechdrs[i].sh_addr      = TO_NATIVE(sechdrs[i].sh_addr);
486                 sechdrs[i].sh_offset    = TO_NATIVE(sechdrs[i].sh_offset);
487                 sechdrs[i].sh_size      = TO_NATIVE(sechdrs[i].sh_size);
488                 sechdrs[i].sh_link      = TO_NATIVE(sechdrs[i].sh_link);
489                 sechdrs[i].sh_info      = TO_NATIVE(sechdrs[i].sh_info);
490                 sechdrs[i].sh_addralign = TO_NATIVE(sechdrs[i].sh_addralign);
491                 sechdrs[i].sh_entsize   = TO_NATIVE(sechdrs[i].sh_entsize);
492         }
493         /* Find symbol table. */
494         secstrings = (void *)hdr + sechdrs[info->secindex_strings].sh_offset;
495         for (i = 1; i < info->num_sections; i++) {
496                 const char *secname;
497                 int nobits = sechdrs[i].sh_type == SHT_NOBITS;
498 
499                 if (!nobits && sechdrs[i].sh_offset > info->size) {
500                         fatal("%s is truncated. sechdrs[i].sh_offset=%lu > "
501                               "sizeof(*hrd)=%zu\n", filename,
502                               (unsigned long)sechdrs[i].sh_offset,
503                               sizeof(*hdr));
504                         return 0;
505                 }
506                 secname = secstrings + sechdrs[i].sh_name;
507                 if (strcmp(secname, ".modinfo") == 0) {
508                         if (nobits)
509                                 fatal("%s has NOBITS .modinfo\n", filename);
510                         info->modinfo = (void *)hdr + sechdrs[i].sh_offset;
511                         info->modinfo_len = sechdrs[i].sh_size;
512                 } else if (strcmp(secname, "__ksymtab") == 0)
513                         info->export_sec = i;
514                 else if (strcmp(secname, "__ksymtab_unused") == 0)
515                         info->export_unused_sec = i;
516                 else if (strcmp(secname, "__ksymtab_gpl") == 0)
517                         info->export_gpl_sec = i;
518                 else if (strcmp(secname, "__ksymtab_unused_gpl") == 0)
519                         info->export_unused_gpl_sec = i;
520                 else if (strcmp(secname, "__ksymtab_gpl_future") == 0)
521                         info->export_gpl_future_sec = i;
522 
523                 if (sechdrs[i].sh_type == SHT_SYMTAB) {
524                         unsigned int sh_link_idx;
525                         symtab_idx = i;
526                         info->symtab_start = (void *)hdr +
527                             sechdrs[i].sh_offset;
528                         info->symtab_stop  = (void *)hdr +
529                             sechdrs[i].sh_offset + sechdrs[i].sh_size;
530                         sh_link_idx = sechdrs[i].sh_link;
531                         info->strtab       = (void *)hdr +
532                             sechdrs[sh_link_idx].sh_offset;
533                 }
534 
535                 /* 32bit section no. table? ("more than 64k sections") */
536                 if (sechdrs[i].sh_type == SHT_SYMTAB_SHNDX) {
537                         symtab_shndx_idx = i;
538                         info->symtab_shndx_start = (void *)hdr +
539                             sechdrs[i].sh_offset;
540                         info->symtab_shndx_stop  = (void *)hdr +
541                             sechdrs[i].sh_offset + sechdrs[i].sh_size;
542                 }
543         }
544         if (!info->symtab_start)
545                 fatal("%s has no symtab?\n", filename);
546 
547         /* Fix endianness in symbols */
548         for (sym = info->symtab_start; sym < info->symtab_stop; sym++) {
549                 sym->st_shndx = TO_NATIVE(sym->st_shndx);
550                 sym->st_name  = TO_NATIVE(sym->st_name);
551                 sym->st_value = TO_NATIVE(sym->st_value);
552                 sym->st_size  = TO_NATIVE(sym->st_size);
553         }
554 
555         if (symtab_shndx_idx != ~0U) {
556                 Elf32_Word *p;
557                 if (symtab_idx != sechdrs[symtab_shndx_idx].sh_link)
558                         fatal("%s: SYMTAB_SHNDX has bad sh_link: %u!=%u\n",
559                               filename, sechdrs[symtab_shndx_idx].sh_link,
560                               symtab_idx);
561                 /* Fix endianness */
562                 for (p = info->symtab_shndx_start; p < info->symtab_shndx_stop;
563                      p++)
564                         *p = TO_NATIVE(*p);
565         }
566 
567         return 1;
568 }
569 
570 static void parse_elf_finish(struct elf_info *info)
571 {
572         release_file(info->hdr, info->size);
573 }
574 
575 static int ignore_undef_symbol(struct elf_info *info, const char *symname)
576 {
577         /* ignore __this_module, it will be resolved shortly */
578         if (strcmp(symname, VMLINUX_SYMBOL_STR(__this_module)) == 0)
579                 return 1;
580         /* ignore global offset table */
581         if (strcmp(symname, "_GLOBAL_OFFSET_TABLE_") == 0)
582                 return 1;
583         if (info->hdr->e_machine == EM_PPC)
584                 /* Special register function linked on all modules during final link of .ko */
585                 if (strncmp(symname, "_restgpr_", sizeof("_restgpr_") - 1) == 0 ||
586                     strncmp(symname, "_savegpr_", sizeof("_savegpr_") - 1) == 0 ||
587                     strncmp(symname, "_rest32gpr_", sizeof("_rest32gpr_") - 1) == 0 ||
588                     strncmp(symname, "_save32gpr_", sizeof("_save32gpr_") - 1) == 0 ||
589                     strncmp(symname, "_restvr_", sizeof("_restvr_") - 1) == 0 ||
590                     strncmp(symname, "_savevr_", sizeof("_savevr_") - 1) == 0)
591                         return 1;
592         if (info->hdr->e_machine == EM_PPC64)
593                 /* Special register function linked on all modules during final link of .ko */
594                 if (strncmp(symname, "_restgpr0_", sizeof("_restgpr0_") - 1) == 0 ||
595                     strncmp(symname, "_savegpr0_", sizeof("_savegpr0_") - 1) == 0 ||
596                     strncmp(symname, "_restvr_", sizeof("_restvr_") - 1) == 0 ||
597                     strncmp(symname, "_savevr_", sizeof("_savevr_") - 1) == 0 ||
598                     strcmp(symname, ".TOC.") == 0)
599                         return 1;
600         /* Do not ignore this symbol */
601         return 0;
602 }
603 
604 #define CRC_PFX     VMLINUX_SYMBOL_STR(__crc_)
605 #define KSYMTAB_PFX VMLINUX_SYMBOL_STR(__ksymtab_)
606 
607 static void handle_modversions(struct module *mod, struct elf_info *info,
608                                Elf_Sym *sym, const char *symname)
609 {
610         unsigned int crc;
611         enum export export;
612         bool is_crc = false;
613 
614         if ((!is_vmlinux(mod->name) || mod->is_dot_o) &&
615             strncmp(symname, "__ksymtab", 9) == 0)
616                 export = export_from_secname(info, get_secindex(info, sym));
617         else
618                 export = export_from_sec(info, get_secindex(info, sym));
619 
620         /* CRC'd symbol */
621         if (strncmp(symname, CRC_PFX, strlen(CRC_PFX)) == 0) {
622                 is_crc = true;
623                 crc = (unsigned int) sym->st_value;
624                 if (sym->st_shndx != SHN_UNDEF && sym->st_shndx != SHN_ABS) {
625                         unsigned int *crcp;
626 
627                         /* symbol points to the CRC in the ELF object */
628                         crcp = (void *)info->hdr + sym->st_value +
629                                info->sechdrs[sym->st_shndx].sh_offset -
630                                (info->hdr->e_type != ET_REL ?
631                                 info->sechdrs[sym->st_shndx].sh_addr : 0);
632                         crc = *crcp;
633                 }
634                 sym_update_crc(symname + strlen(CRC_PFX), mod, crc,
635                                 export);
636         }
637 
638         switch (sym->st_shndx) {
639         case SHN_COMMON:
640                 if (!strncmp(symname, "__gnu_lto_", sizeof("__gnu_lto_")-1)) {
641                         /* Should warn here, but modpost runs before the linker */
642                 } else
643                         warn("\"%s\" [%s] is COMMON symbol\n", symname, mod->name);
644                 break;
645         case SHN_UNDEF:
646                 /* undefined symbol */
647                 if (ELF_ST_BIND(sym->st_info) != STB_GLOBAL &&
648                     ELF_ST_BIND(sym->st_info) != STB_WEAK)
649                         break;
650                 if (ignore_undef_symbol(info, symname))
651                         break;
652 /* cope with newer glibc (2.3.4 or higher) STT_ definition in elf.h */
653 #if defined(STT_REGISTER) || defined(STT_SPARC_REGISTER)
654 /* add compatibility with older glibc */
655 #ifndef STT_SPARC_REGISTER
656 #define STT_SPARC_REGISTER STT_REGISTER
657 #endif
658                 if (info->hdr->e_machine == EM_SPARC ||
659                     info->hdr->e_machine == EM_SPARCV9) {
660                         /* Ignore register directives. */
661                         if (ELF_ST_TYPE(sym->st_info) == STT_SPARC_REGISTER)
662                                 break;
663                         if (symname[0] == '.') {
664                                 char *munged = strdup(symname);
665                                 munged[0] = '_';
666                                 munged[1] = toupper(munged[1]);
667                                 symname = munged;
668                         }
669                 }
670 #endif
671 
672 #ifdef CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX
673                 if (symname[0] != '_')
674                         break;
675                 else
676                         symname++;
677 #endif
678                 if (is_crc) {
679                         const char *e = is_vmlinux(mod->name) ?"":".ko";
680                         warn("EXPORT symbol \"%s\" [%s%s] version generation failed, symbol will not be versioned.\n", symname + strlen(CRC_PFX), mod->name, e);
681                 }
682                 mod->unres = alloc_symbol(symname,
683                                           ELF_ST_BIND(sym->st_info) == STB_WEAK,
684                                           mod->unres);
685                 break;
686         default:
687                 /* All exported symbols */
688                 if (strncmp(symname, KSYMTAB_PFX, strlen(KSYMTAB_PFX)) == 0) {
689                         sym_add_exported(symname + strlen(KSYMTAB_PFX), mod,
690                                         export);
691                 }
692                 if (strcmp(symname, VMLINUX_SYMBOL_STR(init_module)) == 0)
693                         mod->has_init = 1;
694                 if (strcmp(symname, VMLINUX_SYMBOL_STR(cleanup_module)) == 0)
695                         mod->has_cleanup = 1;
696                 break;
697         }
698 }
699 
700 /**
701  * Parse tag=value strings from .modinfo section
702  **/
703 static char *next_string(char *string, unsigned long *secsize)
704 {
705         /* Skip non-zero chars */
706         while (string[0]) {
707                 string++;
708                 if ((*secsize)-- <= 1)
709                         return NULL;
710         }
711 
712         /* Skip any zero padding. */
713         while (!string[0]) {
714                 string++;
715                 if ((*secsize)-- <= 1)
716                         return NULL;
717         }
718         return string;
719 }
720 
721 static char *get_next_modinfo(void *modinfo, unsigned long modinfo_len,
722                               const char *tag, char *info)
723 {
724         char *p;
725         unsigned int taglen = strlen(tag);
726         unsigned long size = modinfo_len;
727 
728         if (info) {
729                 size -= info - (char *)modinfo;
730                 modinfo = next_string(info, &size);
731         }
732 
733         for (p = modinfo; p; p = next_string(p, &size)) {
734                 if (strncmp(p, tag, taglen) == 0 && p[taglen] == '=')
735                         return p + taglen + 1;
736         }
737         return NULL;
738 }
739 
740 static char *get_modinfo(void *modinfo, unsigned long modinfo_len,
741                          const char *tag)
742 
743 {
744         return get_next_modinfo(modinfo, modinfo_len, tag, NULL);
745 }
746 
747 /**
748  * Test if string s ends in string sub
749  * return 0 if match
750  **/
751 static int strrcmp(const char *s, const char *sub)
752 {
753         int slen, sublen;
754 
755         if (!s || !sub)
756                 return 1;
757 
758         slen = strlen(s);
759         sublen = strlen(sub);
760 
761         if ((slen == 0) || (sublen == 0))
762                 return 1;
763 
764         if (sublen > slen)
765                 return 1;
766 
767         return memcmp(s + slen - sublen, sub, sublen);
768 }
769 
770 static const char *sym_name(struct elf_info *elf, Elf_Sym *sym)
771 {
772         if (sym)
773                 return elf->strtab + sym->st_name;
774         else
775                 return "(unknown)";
776 }
777 
778 static const char *sec_name(struct elf_info *elf, int secindex)
779 {
780         Elf_Shdr *sechdrs = elf->sechdrs;
781         return (void *)elf->hdr +
782                 elf->sechdrs[elf->secindex_strings].sh_offset +
783                 sechdrs[secindex].sh_name;
784 }
785 
786 static const char *sech_name(struct elf_info *elf, Elf_Shdr *sechdr)
787 {
788         return (void *)elf->hdr +
789                 elf->sechdrs[elf->secindex_strings].sh_offset +
790                 sechdr->sh_name;
791 }
792 
793 /* The pattern is an array of simple patterns.
794  * "foo" will match an exact string equal to "foo"
795  * "*foo" will match a string that ends with "foo"
796  * "foo*" will match a string that begins with "foo"
797  * "*foo*" will match a string that contains "foo"
798  */
799 static int match(const char *sym, const char * const pat[])
800 {
801         const char *p;
802         while (*pat) {
803                 p = *pat++;
804                 const char *endp = p + strlen(p) - 1;
805 
806                 /* "*foo*" */
807                 if (*p == '*' && *endp == '*') {
808                         char *here, *bare = strndup(p + 1, strlen(p) - 2);
809 
810                         here = strstr(sym, bare);
811                         free(bare);
812                         if (here != NULL)
813                                 return 1;
814                 }
815                 /* "*foo" */
816                 else if (*p == '*') {
817                         if (strrcmp(sym, p + 1) == 0)
818                                 return 1;
819                 }
820                 /* "foo*" */
821                 else if (*endp == '*') {
822                         if (strncmp(sym, p, strlen(p) - 1) == 0)
823                                 return 1;
824                 }
825                 /* no wildcards */
826                 else {
827                         if (strcmp(p, sym) == 0)
828                                 return 1;
829                 }
830         }
831         /* no match */
832         return 0;
833 }
834 
835 /* sections that we do not want to do full section mismatch check on */
836 static const char *const section_white_list[] =
837 {
838         ".comment*",
839         ".debug*",
840         ".cranges",             /* sh64 */
841         ".zdebug*",             /* Compressed debug sections. */
842         ".GCC-command-line",    /* mn10300 */
843         ".GCC.command.line",    /* record-gcc-switches, non mn10300 */
844         ".mdebug*",        /* alpha, score, mips etc. */
845         ".pdr",            /* alpha, score, mips etc. */
846         ".stab*",
847         ".note*",
848         ".got*",
849         ".toc*",
850         ".xt.prop",                              /* xtensa */
851         ".xt.lit",         /* xtensa */
852         ".arcextmap*",                  /* arc */
853         ".gnu.linkonce.arcext*",        /* arc : modules */
854         ".cmem*",                       /* EZchip */
855         ".fmt_slot*",                   /* EZchip */
856         ".gnu.lto*",
857         ".discard.*",
858         NULL
859 };
860 
861 /*
862  * This is used to find sections missing the SHF_ALLOC flag.
863  * The cause of this is often a section specified in assembler
864  * without "ax" / "aw".
865  */
866 static void check_section(const char *modname, struct elf_info *elf,
867                           Elf_Shdr *sechdr)
868 {
869         const char *sec = sech_name(elf, sechdr);
870 
871         if (sechdr->sh_type == SHT_PROGBITS &&
872             !(sechdr->sh_flags & SHF_ALLOC) &&
873             !match(sec, section_white_list)) {
874                 warn("%s (%s): unexpected non-allocatable section.\n"
875                      "Did you forget to use \"ax\"/\"aw\" in a .S file?\n"
876                      "Note that for example <linux/init.h> contains\n"
877                      "section definitions for use in .S files.\n\n",
878                      modname, sec);
879         }
880 }
881 
882 
883 
884 #define ALL_INIT_DATA_SECTIONS \
885         ".init.setup", ".init.rodata", ".meminit.rodata", \
886         ".init.data", ".meminit.data"
887 #define ALL_EXIT_DATA_SECTIONS \
888         ".exit.data", ".memexit.data"
889 
890 #define ALL_INIT_TEXT_SECTIONS \
891         ".init.text", ".meminit.text"
892 #define ALL_EXIT_TEXT_SECTIONS \
893         ".exit.text", ".memexit.text"
894 
895 #define ALL_PCI_INIT_SECTIONS   \
896         ".pci_fixup_early", ".pci_fixup_header", ".pci_fixup_final", \
897         ".pci_fixup_enable", ".pci_fixup_resume", \
898         ".pci_fixup_resume_early", ".pci_fixup_suspend"
899 
900 #define ALL_XXXINIT_SECTIONS MEM_INIT_SECTIONS
901 #define ALL_XXXEXIT_SECTIONS MEM_EXIT_SECTIONS
902 
903 #define ALL_INIT_SECTIONS INIT_SECTIONS, ALL_XXXINIT_SECTIONS
904 #define ALL_EXIT_SECTIONS EXIT_SECTIONS, ALL_XXXEXIT_SECTIONS
905 
906 #define DATA_SECTIONS ".data", ".data.rel"
907 #define TEXT_SECTIONS ".text", ".text.unlikely", ".sched.text", \
908                 ".kprobes.text", ".cpuidle.text"
909 #define OTHER_TEXT_SECTIONS ".ref.text", ".head.text", ".spinlock.text", \
910                 ".fixup", ".entry.text", ".exception.text", ".text.*", \
911                 ".coldtext"
912 
913 #define INIT_SECTIONS      ".init.*"
914 #define MEM_INIT_SECTIONS  ".meminit.*"
915 
916 #define EXIT_SECTIONS      ".exit.*"
917 #define MEM_EXIT_SECTIONS  ".memexit.*"
918 
919 #define ALL_TEXT_SECTIONS  ALL_INIT_TEXT_SECTIONS, ALL_EXIT_TEXT_SECTIONS, \
920                 TEXT_SECTIONS, OTHER_TEXT_SECTIONS
921 
922 /* init data sections */
923 static const char *const init_data_sections[] =
924         { ALL_INIT_DATA_SECTIONS, NULL };
925 
926 /* all init sections */
927 static const char *const init_sections[] = { ALL_INIT_SECTIONS, NULL };
928 
929 /* All init and exit sections (code + data) */
930 static const char *const init_exit_sections[] =
931         {ALL_INIT_SECTIONS, ALL_EXIT_SECTIONS, NULL };
932 
933 /* all text sections */
934 static const char *const text_sections[] = { ALL_TEXT_SECTIONS, NULL };
935 
936 /* data section */
937 static const char *const data_sections[] = { DATA_SECTIONS, NULL };
938 
939 
940 /* symbols in .data that may refer to init/exit sections */
941 #define DEFAULT_SYMBOL_WHITE_LIST                                       \
942         "*driver",                                                      \
943         "*_template", /* scsi uses *_template a lot */                  \
944         "*_timer",    /* arm uses ops structures named _timer a lot */  \
945         "*_sht",      /* scsi also used *_sht to some extent */         \
946         "*_ops",                                                        \
947         "*_probe",                                                      \
948         "*_probe_one",                                                  \
949         "*_console"
950 
951 static const char *const head_sections[] = { ".head.text*", NULL };
952 static const char *const linker_symbols[] =
953         { "__init_begin", "_sinittext", "_einittext", NULL };
954 static const char *const optim_symbols[] = { "*.constprop.*", NULL };
955 
956 enum mismatch {
957         TEXT_TO_ANY_INIT,
958         DATA_TO_ANY_INIT,
959         TEXT_TO_ANY_EXIT,
960         DATA_TO_ANY_EXIT,
961         XXXINIT_TO_SOME_INIT,
962         XXXEXIT_TO_SOME_EXIT,
963         ANY_INIT_TO_ANY_EXIT,
964         ANY_EXIT_TO_ANY_INIT,
965         EXPORT_TO_INIT_EXIT,
966         EXTABLE_TO_NON_TEXT,
967 };
968 
969 /**
970  * Describe how to match sections on different criterias:
971  *
972  * @fromsec: Array of sections to be matched.
973  *
974  * @bad_tosec: Relocations applied to a section in @fromsec to a section in
975  * this array is forbidden (black-list).  Can be empty.
976  *
977  * @good_tosec: Relocations applied to a section in @fromsec must be
978  * targetting sections in this array (white-list).  Can be empty.
979  *
980  * @mismatch: Type of mismatch.
981  *
982  * @symbol_white_list: Do not match a relocation to a symbol in this list
983  * even if it is targetting a section in @bad_to_sec.
984  *
985  * @handler: Specific handler to call when a match is found.  If NULL,
986  * default_mismatch_handler() will be called.
987  *
988  */
989 struct sectioncheck {
990         const char *fromsec[20];
991         const char *bad_tosec[20];
992         const char *good_tosec[20];
993         enum mismatch mismatch;
994         const char *symbol_white_list[20];
995         void (*handler)(const char *modname, struct elf_info *elf,
996                         const struct sectioncheck* const mismatch,
997                         Elf_Rela *r, Elf_Sym *sym, const char *fromsec);
998 
999 };
1000 
1001 static void extable_mismatch_handler(const char *modname, struct elf_info *elf,
1002                                      const struct sectioncheck* const mismatch,
1003                                      Elf_Rela *r, Elf_Sym *sym,
1004                                      const char *fromsec);
1005 
1006 static const struct sectioncheck sectioncheck[] = {
1007 /* Do not reference init/exit code/data from
1008  * normal code and data
1009  */
1010 {
1011         .fromsec = { TEXT_SECTIONS, NULL },
1012         .bad_tosec = { ALL_INIT_SECTIONS, NULL },
1013         .mismatch = TEXT_TO_ANY_INIT,
1014         .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
1015 },
1016 {
1017         .fromsec = { DATA_SECTIONS, NULL },
1018         .bad_tosec = { ALL_XXXINIT_SECTIONS, NULL },
1019         .mismatch = DATA_TO_ANY_INIT,
1020         .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
1021 },
1022 {
1023         .fromsec = { DATA_SECTIONS, NULL },
1024         .bad_tosec = { INIT_SECTIONS, NULL },
1025         .mismatch = DATA_TO_ANY_INIT,
1026         .symbol_white_list = {
1027                 "*_template", "*_timer", "*_sht", "*_ops",
1028                 "*_probe", "*_probe_one", "*_console", NULL
1029         },
1030 },
1031 {
1032         .fromsec = { TEXT_SECTIONS, NULL },
1033         .bad_tosec = { ALL_EXIT_SECTIONS, NULL },
1034         .mismatch = TEXT_TO_ANY_EXIT,
1035         .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
1036 },
1037 {
1038         .fromsec = { DATA_SECTIONS, NULL },
1039         .bad_tosec = { ALL_EXIT_SECTIONS, NULL },
1040         .mismatch = DATA_TO_ANY_EXIT,
1041         .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
1042 },
1043 /* Do not reference init code/data from meminit code/data */
1044 {
1045         .fromsec = { ALL_XXXINIT_SECTIONS, NULL },
1046         .bad_tosec = { INIT_SECTIONS, NULL },
1047         .mismatch = XXXINIT_TO_SOME_INIT,
1048         .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
1049 },
1050 /* Do not reference exit code/data from memexit code/data */
1051 {
1052         .fromsec = { ALL_XXXEXIT_SECTIONS, NULL },
1053         .bad_tosec = { EXIT_SECTIONS, NULL },
1054         .mismatch = XXXEXIT_TO_SOME_EXIT,
1055         .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
1056 },
1057 /* Do not use exit code/data from init code */
1058 {
1059         .fromsec = { ALL_INIT_SECTIONS, NULL },
1060         .bad_tosec = { ALL_EXIT_SECTIONS, NULL },
1061         .mismatch = ANY_INIT_TO_ANY_EXIT,
1062         .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
1063 },
1064 /* Do not use init code/data from exit code */
1065 {
1066         .fromsec = { ALL_EXIT_SECTIONS, NULL },
1067         .bad_tosec = { ALL_INIT_SECTIONS, NULL },
1068         .mismatch = ANY_EXIT_TO_ANY_INIT,
1069         .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
1070 },
1071 {
1072         .fromsec = { ALL_PCI_INIT_SECTIONS, NULL },
1073         .bad_tosec = { INIT_SECTIONS, NULL },
1074         .mismatch = ANY_INIT_TO_ANY_EXIT,
1075         .symbol_white_list = { NULL },
1076 },
1077 /* Do not export init/exit functions or data */
1078 {
1079         .fromsec = { "__ksymtab*", NULL },
1080         .bad_tosec = { INIT_SECTIONS, EXIT_SECTIONS, NULL },
1081         .mismatch = EXPORT_TO_INIT_EXIT,
1082         .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
1083 },
1084 {
1085         .fromsec = { "__ex_table", NULL },
1086         /* If you're adding any new black-listed sections in here, consider
1087          * adding a special 'printer' for them in scripts/check_extable.
1088          */
1089         .bad_tosec = { ".altinstr_replacement", NULL },
1090         .good_tosec = {ALL_TEXT_SECTIONS , NULL},
1091         .mismatch = EXTABLE_TO_NON_TEXT,
1092         .handler = extable_mismatch_handler,
1093 }
1094 };
1095 
1096 static const struct sectioncheck *section_mismatch(
1097                 const char *fromsec, const char *tosec)
1098 {
1099         int i;
1100         int elems = sizeof(sectioncheck) / sizeof(struct sectioncheck);
1101         const struct sectioncheck *check = &sectioncheck[0];
1102 
1103         /*
1104          * The target section could be the SHT_NUL section when we're
1105          * handling relocations to un-resolved symbols, trying to match it
1106          * doesn't make much sense and causes build failures on parisc and
1107          * mn10300 architectures.
1108          */
1109         if (*tosec == '\0')
1110                 return NULL;
1111 
1112         for (i = 0; i < elems; i++) {
1113                 if (match(fromsec, check->fromsec)) {
1114                         if (check->bad_tosec[0] && match(tosec, check->bad_tosec))
1115                                 return check;
1116                         if (check->good_tosec[0] && !match(tosec, check->good_tosec))
1117                                 return check;
1118                 }
1119                 check++;
1120         }
1121         return NULL;
1122 }
1123 
1124 /**
1125  * Whitelist to allow certain references to pass with no warning.
1126  *
1127  * Pattern 1:
1128  *   If a module parameter is declared __initdata and permissions=0
1129  *   then this is legal despite the warning generated.
1130  *   We cannot see value of permissions here, so just ignore
1131  *   this pattern.
1132  *   The pattern is identified by:
1133  *   tosec   = .init.data
1134  *   fromsec = .data*
1135  *   atsym   =__param*
1136  *
1137  * Pattern 1a:
1138  *   module_param_call() ops can refer to __init set function if permissions=0
1139  *   The pattern is identified by:
1140  *   tosec   = .init.text
1141  *   fromsec = .data*
1142  *   atsym   = __param_ops_*
1143  *
1144  * Pattern 2:
1145  *   Many drivers utilise a *driver container with references to
1146  *   add, remove, probe functions etc.
1147  *   the pattern is identified by:
1148  *   tosec   = init or exit section
1149  *   fromsec = data section
1150  *   atsym = *driver, *_template, *_sht, *_ops, *_probe,
1151  *           *probe_one, *_console, *_timer
1152  *
1153  * Pattern 3:
1154  *   Whitelist all references from .head.text to any init section
1155  *
1156  * Pattern 4:
1157  *   Some symbols belong to init section but still it is ok to reference
1158  *   these from non-init sections as these symbols don't have any memory
1159  *   allocated for them and symbol address and value are same. So even
1160  *   if init section is freed, its ok to reference those symbols.
1161  *   For ex. symbols marking the init section boundaries.
1162  *   This pattern is identified by
1163  *   refsymname = __init_begin, _sinittext, _einittext
1164  *
1165  * Pattern 5:
1166  *   GCC may optimize static inlines when fed constant arg(s) resulting
1167  *   in functions like cpumask_empty() -- generating an associated symbol
1168  *   cpumask_empty.constprop.3 that appears in the audit.  If the const that
1169  *   is passed in comes from __init, like say nmi_ipi_mask, we get a
1170  *   meaningless section warning.  May need to add isra symbols too...
1171  *   This pattern is identified by
1172  *   tosec   = init section
1173  *   fromsec = text section
1174  *   refsymname = *.constprop.*
1175  *
1176  **/
1177 static int secref_whitelist(const struct sectioncheck *mismatch,
1178                             const char *fromsec, const char *fromsym,
1179                             const char *tosec, const char *tosym)
1180 {
1181         /* Check for pattern 1 */
1182         if (match(tosec, init_data_sections) &&
1183             match(fromsec, data_sections) &&
1184             (strncmp(fromsym, "__param", strlen("__param")) == 0))
1185                 return 0;
1186 
1187         /* Check for pattern 1a */
1188         if (strcmp(tosec, ".init.text") == 0 &&
1189             match(fromsec, data_sections) &&
1190             (strncmp(fromsym, "__param_ops_", strlen("__param_ops_")) == 0))
1191                 return 0;
1192 
1193         /* Check for pattern 2 */
1194         if (match(tosec, init_exit_sections) &&
1195             match(fromsec, data_sections) &&
1196             match(fromsym, mismatch->symbol_white_list))
1197                 return 0;
1198 
1199         /* Check for pattern 3 */
1200         if (match(fromsec, head_sections) &&
1201             match(tosec, init_sections))
1202                 return 0;
1203 
1204         /* Check for pattern 4 */
1205         if (match(tosym, linker_symbols))
1206                 return 0;
1207 
1208         /* Check for pattern 5 */
1209         if (match(fromsec, text_sections) &&
1210             match(tosec, init_sections) &&
1211             match(fromsym, optim_symbols))
1212                 return 0;
1213 
1214         return 1;
1215 }
1216 
1217 /**
1218  * Find symbol based on relocation record info.
1219  * In some cases the symbol supplied is a valid symbol so
1220  * return refsym. If st_name != 0 we assume this is a valid symbol.
1221  * In other cases the symbol needs to be looked up in the symbol table
1222  * based on section and address.
1223  *  **/
1224 static Elf_Sym *find_elf_symbol(struct elf_info *elf, Elf64_Sword addr,
1225                                 Elf_Sym *relsym)
1226 {
1227         Elf_Sym *sym;
1228         Elf_Sym *near = NULL;
1229         Elf64_Sword distance = 20;
1230         Elf64_Sword d;
1231         unsigned int relsym_secindex;
1232 
1233         if (relsym->st_name != 0)
1234                 return relsym;
1235 
1236         relsym_secindex = get_secindex(elf, relsym);
1237         for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) {
1238                 if (get_secindex(elf, sym) != relsym_secindex)
1239                         continue;
1240                 if (ELF_ST_TYPE(sym->st_info) == STT_SECTION)
1241                         continue;
1242                 if (sym->st_value == addr)
1243                         return sym;
1244                 /* Find a symbol nearby - addr are maybe negative */
1245                 d = sym->st_value - addr;
1246                 if (d < 0)
1247                         d = addr - sym->st_value;
1248                 if (d < distance) {
1249                         distance = d;
1250                         near = sym;
1251                 }
1252         }
1253         /* We need a close match */
1254         if (distance < 20)
1255                 return near;
1256         else
1257                 return NULL;
1258 }
1259 
1260 static inline int is_arm_mapping_symbol(const char *str)
1261 {
1262         return str[0] == '$' && strchr("axtd", str[1])
1263                && (str[2] == '\0' || str[2] == '.');
1264 }
1265 
1266 /*
1267  * If there's no name there, ignore it; likewise, ignore it if it's
1268  * one of the magic symbols emitted used by current ARM tools.
1269  *
1270  * Otherwise if find_symbols_between() returns those symbols, they'll
1271  * fail the whitelist tests and cause lots of false alarms ... fixable
1272  * only by merging __exit and __init sections into __text, bloating
1273  * the kernel (which is especially evil on embedded platforms).
1274  */
1275 static inline int is_valid_name(struct elf_info *elf, Elf_Sym *sym)
1276 {
1277         const char *name = elf->strtab + sym->st_name;
1278 
1279         if (!name || !strlen(name))
1280                 return 0;
1281         return !is_arm_mapping_symbol(name);
1282 }
1283 
1284 /*
1285  * Find symbols before or equal addr and after addr - in the section sec.
1286  * If we find two symbols with equal offset prefer one with a valid name.
1287  * The ELF format may have a better way to detect what type of symbol
1288  * it is, but this works for now.
1289  **/
1290 static Elf_Sym *find_elf_symbol2(struct elf_info *elf, Elf_Addr addr,
1291                                  const char *sec)
1292 {
1293         Elf_Sym *sym;
1294         Elf_Sym *near = NULL;
1295         Elf_Addr distance = ~0;
1296 
1297         for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) {
1298                 const char *symsec;
1299 
1300                 if (is_shndx_special(sym->st_shndx))
1301                         continue;
1302                 symsec = sec_name(elf, get_secindex(elf, sym));
1303                 if (strcmp(symsec, sec) != 0)
1304                         continue;
1305                 if (!is_valid_name(elf, sym))
1306                         continue;
1307                 if (sym->st_value <= addr) {
1308                         if ((addr - sym->st_value) < distance) {
1309                                 distance = addr - sym->st_value;
1310                                 near = sym;
1311                         } else if ((addr - sym->st_value) == distance) {
1312                                 near = sym;
1313                         }
1314                 }
1315         }
1316         return near;
1317 }
1318 
1319 /*
1320  * Convert a section name to the function/data attribute
1321  * .init.text => __init
1322  * .memexitconst => __memconst
1323  * etc.
1324  *
1325  * The memory of returned value has been allocated on a heap. The user of this
1326  * method should free it after usage.
1327 */
1328 static char *sec2annotation(const char *s)
1329 {
1330         if (match(s, init_exit_sections)) {
1331                 char *p = malloc(20);
1332                 char *r = p;
1333 
1334                 *p++ = '_';
1335                 *p++ = '_';
1336                 if (*s == '.')
1337                         s++;
1338                 while (*s && *s != '.')
1339                         *p++ = *s++;
1340                 *p = '\0';
1341                 if (*s == '.')
1342                         s++;
1343                 if (strstr(s, "rodata") != NULL)
1344                         strcat(p, "const ");
1345                 else if (strstr(s, "data") != NULL)
1346                         strcat(p, "data ");
1347                 else
1348                         strcat(p, " ");
1349                 return r;
1350         } else {
1351                 return strdup("");
1352         }
1353 }
1354 
1355 static int is_function(Elf_Sym *sym)
1356 {
1357         if (sym)
1358                 return ELF_ST_TYPE(sym->st_info) == STT_FUNC;
1359         else
1360                 return -1;
1361 }
1362 
1363 static void print_section_list(const char * const list[20])
1364 {
1365         const char *const *s = list;
1366 
1367         while (*s) {
1368                 fprintf(stderr, "%s", *s);
1369                 s++;
1370                 if (*s)
1371                         fprintf(stderr, ", ");
1372         }
1373         fprintf(stderr, "\n");
1374 }
1375 
1376 static inline void get_pretty_name(int is_func, const char** name, const char** name_p)
1377 {
1378         switch (is_func) {
1379         case 0: *name = "variable"; *name_p = ""; break;
1380         case 1: *name = "function"; *name_p = "()"; break;
1381         default: *name = "(unknown reference)"; *name_p = ""; break;
1382         }
1383 }
1384 
1385 /*
1386  * Print a warning about a section mismatch.
1387  * Try to find symbols near it so user can find it.
1388  * Check whitelist before warning - it may be a false positive.
1389  */
1390 static void report_sec_mismatch(const char *modname,
1391                                 const struct sectioncheck *mismatch,
1392                                 const char *fromsec,
1393                                 unsigned long long fromaddr,
1394                                 const char *fromsym,
1395                                 int from_is_func,
1396                                 const char *tosec, const char *tosym,
1397                                 int to_is_func)
1398 {
1399         const char *from, *from_p;
1400         const char *to, *to_p;
1401         char *prl_from;
1402         char *prl_to;
1403 
1404         sec_mismatch_count++;
1405         if (!sec_mismatch_verbose)
1406                 return;
1407 
1408         get_pretty_name(from_is_func, &from, &from_p);
1409         get_pretty_name(to_is_func, &to, &to_p);
1410 
1411         warn("%s(%s+0x%llx): Section mismatch in reference from the %s %s%s "
1412              "to the %s %s:%s%s\n",
1413              modname, fromsec, fromaddr, from, fromsym, from_p, to, tosec,
1414              tosym, to_p);
1415 
1416         switch (mismatch->mismatch) {
1417         case TEXT_TO_ANY_INIT:
1418                 prl_from = sec2annotation(fromsec);
1419                 prl_to = sec2annotation(tosec);
1420                 fprintf(stderr,
1421                 "The function %s%s() references\n"
1422                 "the %s %s%s%s.\n"
1423                 "This is often because %s lacks a %s\n"
1424                 "annotation or the annotation of %s is wrong.\n",
1425                 prl_from, fromsym,
1426                 to, prl_to, tosym, to_p,
1427                 fromsym, prl_to, tosym);
1428                 free(prl_from);
1429                 free(prl_to);
1430                 break;
1431         case DATA_TO_ANY_INIT: {
1432                 prl_to = sec2annotation(tosec);
1433                 fprintf(stderr,
1434                 "The variable %s references\n"
1435                 "the %s %s%s%s\n"
1436                 "If the reference is valid then annotate the\n"
1437                 "variable with __init* or __refdata (see linux/init.h) "
1438                 "or name the variable:\n",
1439                 fromsym, to, prl_to, tosym, to_p);
1440                 print_section_list(mismatch->symbol_white_list);
1441                 free(prl_to);
1442                 break;
1443         }
1444         case TEXT_TO_ANY_EXIT:
1445                 prl_to = sec2annotation(tosec);
1446                 fprintf(stderr,
1447                 "The function %s() references a %s in an exit section.\n"
1448                 "Often the %s %s%s has valid usage outside the exit section\n"
1449                 "and the fix is to remove the %sannotation of %s.\n",
1450                 fromsym, to, to, tosym, to_p, prl_to, tosym);
1451                 free(prl_to);
1452                 break;
1453         case DATA_TO_ANY_EXIT: {
1454                 prl_to = sec2annotation(tosec);
1455                 fprintf(stderr,
1456                 "The variable %s references\n"
1457                 "the %s %s%s%s\n"
1458                 "If the reference is valid then annotate the\n"
1459                 "variable with __exit* (see linux/init.h) or "
1460                 "name the variable:\n",
1461                 fromsym, to, prl_to, tosym, to_p);
1462                 print_section_list(mismatch->symbol_white_list);
1463                 free(prl_to);
1464                 break;
1465         }
1466         case XXXINIT_TO_SOME_INIT:
1467         case XXXEXIT_TO_SOME_EXIT:
1468                 prl_from = sec2annotation(fromsec);
1469                 prl_to = sec2annotation(tosec);
1470                 fprintf(stderr,
1471                 "The %s %s%s%s references\n"
1472                 "a %s %s%s%s.\n"
1473                 "If %s is only used by %s then\n"
1474                 "annotate %s with a matching annotation.\n",
1475                 from, prl_from, fromsym, from_p,
1476                 to, prl_to, tosym, to_p,
1477                 tosym, fromsym, tosym);
1478                 free(prl_from);
1479                 free(prl_to);
1480                 break;
1481         case ANY_INIT_TO_ANY_EXIT:
1482                 prl_from = sec2annotation(fromsec);
1483                 prl_to = sec2annotation(tosec);
1484                 fprintf(stderr,
1485                 "The %s %s%s%s references\n"
1486                 "a %s %s%s%s.\n"
1487                 "This is often seen when error handling "
1488                 "in the init function\n"
1489                 "uses functionality in the exit path.\n"
1490                 "The fix is often to remove the %sannotation of\n"
1491                 "%s%s so it may be used outside an exit section.\n",
1492                 from, prl_from, fromsym, from_p,
1493                 to, prl_to, tosym, to_p,
1494                 prl_to, tosym, to_p);
1495                 free(prl_from);
1496                 free(prl_to);
1497                 break;
1498         case ANY_EXIT_TO_ANY_INIT:
1499                 prl_from = sec2annotation(fromsec);
1500                 prl_to = sec2annotation(tosec);
1501                 fprintf(stderr,
1502                 "The %s %s%s%s references\n"
1503                 "a %s %s%s%s.\n"
1504                 "This is often seen when error handling "
1505                 "in the exit function\n"
1506                 "uses functionality in the init path.\n"
1507                 "The fix is often to remove the %sannotation of\n"
1508                 "%s%s so it may be used outside an init section.\n",
1509                 from, prl_from, fromsym, from_p,
1510                 to, prl_to, tosym, to_p,
1511                 prl_to, tosym, to_p);
1512                 free(prl_from);
1513                 free(prl_to);
1514                 break;
1515         case EXPORT_TO_INIT_EXIT:
1516                 prl_to = sec2annotation(tosec);
1517                 fprintf(stderr,
1518                 "The symbol %s is exported and annotated %s\n"
1519                 "Fix this by removing the %sannotation of %s "
1520                 "or drop the export.\n",
1521                 tosym, prl_to, prl_to, tosym);
1522                 free(prl_to);
1523                 break;
1524         case EXTABLE_TO_NON_TEXT:
1525                 fatal("There's a special handler for this mismatch type, "
1526                       "we should never get here.");
1527                 break;
1528         }
1529         fprintf(stderr, "\n");
1530 }
1531 
1532 static void default_mismatch_handler(const char *modname, struct elf_info *elf,
1533                                      const struct sectioncheck* const mismatch,
1534                                      Elf_Rela *r, Elf_Sym *sym, const char *fromsec)
1535 {
1536         const char *tosec;
1537         Elf_Sym *to;
1538         Elf_Sym *from;
1539         const char *tosym;
1540         const char *fromsym;
1541 
1542         from = find_elf_symbol2(elf, r->r_offset, fromsec);
1543         fromsym = sym_name(elf, from);
1544 
1545         if (!strncmp(fromsym, "reference___initcall",
1546                      sizeof("reference___initcall")-1))
1547                 return;
1548 
1549         tosec = sec_name(elf, get_secindex(elf, sym));
1550         to = find_elf_symbol(elf, r->r_addend, sym);
1551         tosym = sym_name(elf, to);
1552 
1553         /* check whitelist - we may ignore it */
1554         if (secref_whitelist(mismatch,
1555                              fromsec, fromsym, tosec, tosym)) {
1556                 report_sec_mismatch(modname, mismatch,
1557                                     fromsec, r->r_offset, fromsym,
1558                                     is_function(from), tosec, tosym,
1559                                     is_function(to));
1560         }
1561 }
1562 
1563 static int is_executable_section(struct elf_info* elf, unsigned int section_index)
1564 {
1565         if (section_index > elf->num_sections)
1566                 fatal("section_index is outside elf->num_sections!\n");
1567 
1568         return ((elf->sechdrs[section_index].sh_flags & SHF_EXECINSTR) == SHF_EXECINSTR);
1569 }
1570 
1571 /*
1572  * We rely on a gross hack in section_rel[a]() calling find_extable_entry_size()
1573  * to know the sizeof(struct exception_table_entry) for the target architecture.
1574  */
1575 static unsigned int extable_entry_size = 0;
1576 static void find_extable_entry_size(const char* const sec, const Elf_Rela* r)
1577 {
1578         /*
1579          * If we're currently checking the second relocation within __ex_table,
1580          * that relocation offset tells us the offsetof(struct
1581          * exception_table_entry, fixup) which is equal to sizeof(struct
1582          * exception_table_entry) divided by two.  We use that to our advantage
1583          * since there's no portable way to get that size as every architecture
1584          * seems to go with different sized types.  Not pretty but better than
1585          * hard-coding the size for every architecture..
1586          */
1587         if (!extable_entry_size)
1588                 extable_entry_size = r->r_offset * 2;
1589 }
1590 
1591 static inline bool is_extable_fault_address(Elf_Rela *r)
1592 {
1593         /*
1594          * extable_entry_size is only discovered after we've handled the
1595          * _second_ relocation in __ex_table, so only abort when we're not
1596          * handling the first reloc and extable_entry_size is zero.
1597          */
1598         if (r->r_offset && extable_entry_size == 0)
1599                 fatal("extable_entry size hasn't been discovered!\n");
1600 
1601         return ((r->r_offset == 0) ||
1602                 (r->r_offset % extable_entry_size == 0));
1603 }
1604 
1605 #define is_second_extable_reloc(Start, Cur, Sec)                        \
1606         (((Cur) == (Start) + 1) && (strcmp("__ex_table", (Sec)) == 0))
1607 
1608 static void report_extable_warnings(const char* modname, struct elf_info* elf,
1609                                     const struct sectioncheck* const mismatch,
1610                                     Elf_Rela* r, Elf_Sym* sym,
1611                                     const char* fromsec, const char* tosec)
1612 {
1613         Elf_Sym* fromsym = find_elf_symbol2(elf, r->r_offset, fromsec);
1614         const char* fromsym_name = sym_name(elf, fromsym);
1615         Elf_Sym* tosym = find_elf_symbol(elf, r->r_addend, sym);
1616         const char* tosym_name = sym_name(elf, tosym);
1617         const char* from_pretty_name;
1618         const char* from_pretty_name_p;
1619         const char* to_pretty_name;
1620         const char* to_pretty_name_p;
1621 
1622         get_pretty_name(is_function(fromsym),
1623                         &from_pretty_name, &from_pretty_name_p);
1624         get_pretty_name(is_function(tosym),
1625                         &to_pretty_name, &to_pretty_name_p);
1626 
1627         warn("%s(%s+0x%lx): Section mismatch in reference"
1628              " from the %s %s%s to the %s %s:%s%s\n",
1629              modname, fromsec, (long)r->r_offset, from_pretty_name,
1630              fromsym_name, from_pretty_name_p,
1631              to_pretty_name, tosec, tosym_name, to_pretty_name_p);
1632 
1633         if (!match(tosec, mismatch->bad_tosec) &&
1634             is_executable_section(elf, get_secindex(elf, sym)))
1635                 fprintf(stderr,
1636                         "The relocation at %s+0x%lx references\n"
1637                         "section \"%s\" which is not in the list of\n"
1638                         "authorized sections.  If you're adding a new section\n"
1639                         "and/or if this reference is valid, add \"%s\" to the\n"
1640                         "list of authorized sections to jump to on fault.\n"
1641                         "This can be achieved by adding \"%s\" to \n"
1642                         "OTHER_TEXT_SECTIONS in scripts/mod/modpost.c.\n",
1643                         fromsec, (long)r->r_offset, tosec, tosec, tosec);
1644 }
1645 
1646 static void extable_mismatch_handler(const char* modname, struct elf_info *elf,
1647                                      const struct sectioncheck* const mismatch,
1648                                      Elf_Rela* r, Elf_Sym* sym,
1649                                      const char *fromsec)
1650 {
1651         const char* tosec = sec_name(elf, get_secindex(elf, sym));
1652 
1653         sec_mismatch_count++;
1654 
1655         if (sec_mismatch_verbose)
1656                 report_extable_warnings(modname, elf, mismatch, r, sym,
1657                                         fromsec, tosec);
1658 
1659         if (match(tosec, mismatch->bad_tosec))
1660                 fatal("The relocation at %s+0x%lx references\n"
1661                       "section \"%s\" which is black-listed.\n"
1662                       "Something is seriously wrong and should be fixed.\n"
1663                       "You might get more information about where this is\n"
1664                       "coming from by using scripts/check_extable.sh %s\n",
1665                       fromsec, (long)r->r_offset, tosec, modname);
1666         else if (!is_executable_section(elf, get_secindex(elf, sym))) {
1667                 if (is_extable_fault_address(r))
1668                         fatal("The relocation at %s+0x%lx references\n"
1669                               "section \"%s\" which is not executable, IOW\n"
1670                               "it is not possible for the kernel to fault\n"
1671                               "at that address.  Something is seriously wrong\n"
1672                               "and should be fixed.\n",
1673                               fromsec, (long)r->r_offset, tosec);
1674                 else
1675                         fatal("The relocation at %s+0x%lx references\n"
1676                               "section \"%s\" which is not executable, IOW\n"
1677                               "the kernel will fault if it ever tries to\n"
1678                               "jump to it.  Something is seriously wrong\n"
1679                               "and should be fixed.\n",
1680                               fromsec, (long)r->r_offset, tosec);
1681         }
1682 }
1683 
1684 static void check_section_mismatch(const char *modname, struct elf_info *elf,
1685                                    Elf_Rela *r, Elf_Sym *sym, const char *fromsec)
1686 {
1687         const char *tosec = sec_name(elf, get_secindex(elf, sym));;
1688         const struct sectioncheck *mismatch = section_mismatch(fromsec, tosec);
1689 
1690         if (mismatch) {
1691                 if (mismatch->handler)
1692                         mismatch->handler(modname, elf,  mismatch,
1693                                           r, sym, fromsec);
1694                 else
1695                         default_mismatch_handler(modname, elf, mismatch,
1696                                                  r, sym, fromsec);
1697         }
1698 }
1699 
1700 static unsigned int *reloc_location(struct elf_info *elf,
1701                                     Elf_Shdr *sechdr, Elf_Rela *r)
1702 {
1703         Elf_Shdr *sechdrs = elf->sechdrs;
1704         int section = sechdr->sh_info;
1705 
1706         return (void *)elf->hdr + sechdrs[section].sh_offset +
1707                 r->r_offset;
1708 }
1709 
1710 static int addend_386_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r)
1711 {
1712         unsigned int r_typ = ELF_R_TYPE(r->r_info);
1713         unsigned int *location = reloc_location(elf, sechdr, r);
1714 
1715         switch (r_typ) {
1716         case R_386_32:
1717                 r->r_addend = TO_NATIVE(*location);
1718                 break;
1719         case R_386_PC32:
1720                 r->r_addend = TO_NATIVE(*location) + 4;
1721                 /* For CONFIG_RELOCATABLE=y */
1722                 if (elf->hdr->e_type == ET_EXEC)
1723                         r->r_addend += r->r_offset;
1724                 break;
1725         }
1726         return 0;
1727 }
1728 
1729 #ifndef R_ARM_CALL
1730 #define R_ARM_CALL      28
1731 #endif
1732 #ifndef R_ARM_JUMP24
1733 #define R_ARM_JUMP24    29
1734 #endif
1735 
1736 #ifndef R_ARM_THM_CALL
1737 #define R_ARM_THM_CALL          10
1738 #endif
1739 #ifndef R_ARM_THM_JUMP24
1740 #define R_ARM_THM_JUMP24        30
1741 #endif
1742 #ifndef R_ARM_THM_JUMP19
1743 #define R_ARM_THM_JUMP19        51
1744 #endif
1745 
1746 static int addend_arm_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r)
1747 {
1748         unsigned int r_typ = ELF_R_TYPE(r->r_info);
1749 
1750         switch (r_typ) {
1751         case R_ARM_ABS32:
1752                 /* From ARM ABI: (S + A) | T */
1753                 r->r_addend = (int)(long)
1754                               (elf->symtab_start + ELF_R_SYM(r->r_info));
1755                 break;
1756         case R_ARM_PC24:
1757         case R_ARM_CALL:
1758         case R_ARM_JUMP24:
1759         case R_ARM_THM_CALL:
1760         case R_ARM_THM_JUMP24:
1761         case R_ARM_THM_JUMP19:
1762                 /* From ARM ABI: ((S + A) | T) - P */
1763                 r->r_addend = (int)(long)(elf->hdr +
1764                               sechdr->sh_offset +
1765                               (r->r_offset - sechdr->sh_addr));
1766                 break;
1767         default:
1768                 return 1;
1769         }
1770         return 0;
1771 }
1772 
1773 static int addend_mips_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r)
1774 {
1775         unsigned int r_typ = ELF_R_TYPE(r->r_info);
1776         unsigned int *location = reloc_location(elf, sechdr, r);
1777         unsigned int inst;
1778 
1779         if (r_typ == R_MIPS_HI16)
1780                 return 1;       /* skip this */
1781         inst = TO_NATIVE(*location);
1782         switch (r_typ) {
1783         case R_MIPS_LO16:
1784                 r->r_addend = inst & 0xffff;
1785                 break;
1786         case R_MIPS_26:
1787                 r->r_addend = (inst & 0x03ffffff) << 2;
1788                 break;
1789         case R_MIPS_32:
1790                 r->r_addend = inst;
1791                 break;
1792         }
1793         return 0;
1794 }
1795 
1796 static void section_rela(const char *modname, struct elf_info *elf,
1797                          Elf_Shdr *sechdr)
1798 {
1799         Elf_Sym  *sym;
1800         Elf_Rela *rela;
1801         Elf_Rela r;
1802         unsigned int r_sym;
1803         const char *fromsec;
1804 
1805         Elf_Rela *start = (void *)elf->hdr + sechdr->sh_offset;
1806         Elf_Rela *stop  = (void *)start + sechdr->sh_size;
1807 
1808         fromsec = sech_name(elf, sechdr);
1809         fromsec += strlen(".rela");
1810         /* if from section (name) is know good then skip it */
1811         if (match(fromsec, section_white_list))
1812                 return;
1813 
1814         for (rela = start; rela < stop; rela++) {
1815                 r.r_offset = TO_NATIVE(rela->r_offset);
1816 #if KERNEL_ELFCLASS == ELFCLASS64
1817                 if (elf->hdr->e_machine == EM_MIPS) {
1818                         unsigned int r_typ;
1819                         r_sym = ELF64_MIPS_R_SYM(rela->r_info);
1820                         r_sym = TO_NATIVE(r_sym);
1821                         r_typ = ELF64_MIPS_R_TYPE(rela->r_info);
1822                         r.r_info = ELF64_R_INFO(r_sym, r_typ);
1823                 } else {
1824                         r.r_info = TO_NATIVE(rela->r_info);
1825                         r_sym = ELF_R_SYM(r.r_info);
1826                 }
1827 #else
1828                 r.r_info = TO_NATIVE(rela->r_info);
1829                 r_sym = ELF_R_SYM(r.r_info);
1830 #endif
1831                 r.r_addend = TO_NATIVE(rela->r_addend);
1832                 sym = elf->symtab_start + r_sym;
1833                 /* Skip special sections */
1834                 if (is_shndx_special(sym->st_shndx))
1835                         continue;
1836                 if (is_second_extable_reloc(start, rela, fromsec))
1837                         find_extable_entry_size(fromsec, &r);
1838                 check_section_mismatch(modname, elf, &r, sym, fromsec);
1839         }
1840 }
1841 
1842 static void section_rel(const char *modname, struct elf_info *elf,
1843                         Elf_Shdr *sechdr)
1844 {
1845         Elf_Sym *sym;
1846         Elf_Rel *rel;
1847         Elf_Rela r;
1848         unsigned int r_sym;
1849         const char *fromsec;
1850 
1851         Elf_Rel *start = (void *)elf->hdr + sechdr->sh_offset;
1852         Elf_Rel *stop  = (void *)start + sechdr->sh_size;
1853 
1854         fromsec = sech_name(elf, sechdr);
1855         fromsec += strlen(".rel");
1856         /* if from section (name) is know good then skip it */
1857         if (match(fromsec, section_white_list))
1858                 return;
1859 
1860         for (rel = start; rel < stop; rel++) {
1861                 r.r_offset = TO_NATIVE(rel->r_offset);
1862 #if KERNEL_ELFCLASS == ELFCLASS64
1863                 if (elf->hdr->e_machine == EM_MIPS) {
1864                         unsigned int r_typ;
1865                         r_sym = ELF64_MIPS_R_SYM(rel->r_info);
1866                         r_sym = TO_NATIVE(r_sym);
1867                         r_typ = ELF64_MIPS_R_TYPE(rel->r_info);
1868                         r.r_info = ELF64_R_INFO(r_sym, r_typ);
1869                 } else {
1870                         r.r_info = TO_NATIVE(rel->r_info);
1871                         r_sym = ELF_R_SYM(r.r_info);
1872                 }
1873 #else
1874                 r.r_info = TO_NATIVE(rel->r_info);
1875                 r_sym = ELF_R_SYM(r.r_info);
1876 #endif
1877                 r.r_addend = 0;
1878                 switch (elf->hdr->e_machine) {
1879                 case EM_386:
1880                         if (addend_386_rel(elf, sechdr, &r))
1881                                 continue;
1882                         break;
1883                 case EM_ARM:
1884                         if (addend_arm_rel(elf, sechdr, &r))
1885                                 continue;
1886                         break;
1887                 case EM_MIPS:
1888                         if (addend_mips_rel(elf, sechdr, &r))
1889                                 continue;
1890                         break;
1891                 }
1892                 sym = elf->symtab_start + r_sym;
1893                 /* Skip special sections */
1894                 if (is_shndx_special(sym->st_shndx))
1895                         continue;
1896                 if (is_second_extable_reloc(start, rel, fromsec))
1897                         find_extable_entry_size(fromsec, &r);
1898                 check_section_mismatch(modname, elf, &r, sym, fromsec);
1899         }
1900 }
1901 
1902 /**
1903  * A module includes a number of sections that are discarded
1904  * either when loaded or when used as built-in.
1905  * For loaded modules all functions marked __init and all data
1906  * marked __initdata will be discarded when the module has been initialized.
1907  * Likewise for modules used built-in the sections marked __exit
1908  * are discarded because __exit marked function are supposed to be called
1909  * only when a module is unloaded which never happens for built-in modules.
1910  * The check_sec_ref() function traverses all relocation records
1911  * to find all references to a section that reference a section that will
1912  * be discarded and warns about it.
1913  **/
1914 static void check_sec_ref(struct module *mod, const char *modname,
1915                           struct elf_info *elf)
1916 {
1917         int i;
1918         Elf_Shdr *sechdrs = elf->sechdrs;
1919 
1920         /* Walk through all sections */
1921         for (i = 0; i < elf->num_sections; i++) {
1922                 check_section(modname, elf, &elf->sechdrs[i]);
1923                 /* We want to process only relocation sections and not .init */
1924                 if (sechdrs[i].sh_type == SHT_RELA)
1925                         section_rela(modname, elf, &elf->sechdrs[i]);
1926                 else if (sechdrs[i].sh_type == SHT_REL)
1927                         section_rel(modname, elf, &elf->sechdrs[i]);
1928         }
1929 }
1930 
1931 static char *remove_dot(char *s)
1932 {
1933         size_t n = strcspn(s, ".");
1934 
1935         if (n && s[n]) {
1936                 size_t m = strspn(s + n + 1, "0123456789");
1937                 if (m && (s[n + m] == '.' || s[n + m] == 0))
1938                         s[n] = 0;
1939         }
1940         return s;
1941 }
1942 
1943 static void read_symbols(char *modname)
1944 {
1945         const char *symname;
1946         char *version;
1947         char *license;
1948         struct module *mod;
1949         struct elf_info info = { };
1950         Elf_Sym *sym;
1951 
1952         if (!parse_elf(&info, modname))
1953                 return;
1954 
1955         mod = new_module(modname);
1956 
1957         /* When there's no vmlinux, don't print warnings about
1958          * unresolved symbols (since there'll be too many ;) */
1959         if (is_vmlinux(modname)) {
1960                 have_vmlinux = 1;
1961                 mod->skip = 1;
1962         }
1963 
1964         license = get_modinfo(info.modinfo, info.modinfo_len, "license");
1965         if (info.modinfo && !license && !is_vmlinux(modname))
1966                 warn("modpost: missing MODULE_LICENSE() in %s\n"
1967                      "see include/linux/module.h for "
1968                      "more information\n", modname);
1969         while (license) {
1970                 if (license_is_gpl_compatible(license))
1971                         mod->gpl_compatible = 1;
1972                 else {
1973                         mod->gpl_compatible = 0;
1974                         break;
1975                 }
1976                 license = get_next_modinfo(info.modinfo, info.modinfo_len,
1977                                            "license", license);
1978         }
1979 
1980         for (sym = info.symtab_start; sym < info.symtab_stop; sym++) {
1981                 symname = remove_dot(info.strtab + sym->st_name);
1982 
1983                 handle_modversions(mod, &info, sym, symname);
1984                 handle_moddevtable(mod, &info, sym, symname);
1985         }
1986         if (!is_vmlinux(modname) ||
1987              (is_vmlinux(modname) && vmlinux_section_warnings))
1988                 check_sec_ref(mod, modname, &info);
1989 
1990         version = get_modinfo(info.modinfo, info.modinfo_len, "version");
1991         if (version)
1992                 maybe_frob_rcs_version(modname, version, info.modinfo,
1993                                        version - (char *)info.hdr);
1994         if (version || (all_versions && !is_vmlinux(modname)))
1995                 get_src_version(modname, mod->srcversion,
1996                                 sizeof(mod->srcversion)-1);
1997 
1998         parse_elf_finish(&info);
1999 
2000         /* Our trick to get versioning for module struct etc. - it's
2001          * never passed as an argument to an exported function, so
2002          * the automatic versioning doesn't pick it up, but it's really
2003          * important anyhow */
2004         if (modversions)
2005                 mod->unres = alloc_symbol("module_layout", 0, mod->unres);
2006 }
2007 
2008 static void read_symbols_from_files(const char *filename)
2009 {
2010         FILE *in = stdin;
2011         char fname[PATH_MAX];
2012 
2013         if (strcmp(filename, "-") != 0) {
2014                 in = fopen(filename, "r");
2015                 if (!in)
2016                         fatal("Can't open filenames file %s: %m", filename);
2017         }
2018 
2019         while (fgets(fname, PATH_MAX, in) != NULL) {
2020                 if (strends(fname, "\n"))
2021                         fname[strlen(fname)-1] = '\0';
2022                 read_symbols(fname);
2023         }
2024 
2025         if (in != stdin)
2026                 fclose(in);
2027 }
2028 
2029 #define SZ 500
2030 
2031 /* We first write the generated file into memory using the
2032  * following helper, then compare to the file on disk and
2033  * only update the later if anything changed */
2034 
2035 void __attribute__((format(printf, 2, 3))) buf_printf(struct buffer *buf,
2036                                                       const char *fmt, ...)
2037 {
2038         char tmp[SZ];
2039         int len;
2040         va_list ap;
2041 
2042         va_start(ap, fmt);
2043         len = vsnprintf(tmp, SZ, fmt, ap);
2044         buf_write(buf, tmp, len);
2045         va_end(ap);
2046 }
2047 
2048 void buf_write(struct buffer *buf, const char *s, int len)
2049 {
2050         if (buf->size - buf->pos < len) {
2051                 buf->size += len + SZ;
2052                 buf->p = realloc(buf->p, buf->size);
2053         }
2054         strncpy(buf->p + buf->pos, s, len);
2055         buf->pos += len;
2056 }
2057 
2058 static void check_for_gpl_usage(enum export exp, const char *m, const char *s)
2059 {
2060         const char *e = is_vmlinux(m) ?"":".ko";
2061 
2062         switch (exp) {
2063         case export_gpl:
2064                 fatal("modpost: GPL-incompatible module %s%s "
2065                       "uses GPL-only symbol '%s'\n", m, e, s);
2066                 break;
2067         case export_unused_gpl:
2068                 fatal("modpost: GPL-incompatible module %s%s "
2069                       "uses GPL-only symbol marked UNUSED '%s'\n", m, e, s);
2070                 break;
2071         case export_gpl_future:
2072                 warn("modpost: GPL-incompatible module %s%s "
2073                       "uses future GPL-only symbol '%s'\n", m, e, s);
2074                 break;
2075         case export_plain:
2076         case export_unused:
2077         case export_unknown:
2078                 /* ignore */
2079                 break;
2080         }
2081 }
2082 
2083 static void check_for_unused(enum export exp, const char *m, const char *s)
2084 {
2085         const char *e = is_vmlinux(m) ?"":".ko";
2086 
2087         switch (exp) {
2088         case export_unused:
2089         case export_unused_gpl:
2090                 warn("modpost: module %s%s "
2091                       "uses symbol '%s' marked UNUSED\n", m, e, s);
2092                 break;
2093         default:
2094                 /* ignore */
2095                 break;
2096         }
2097 }
2098 
2099 static void check_exports(struct module *mod)
2100 {
2101         struct symbol *s, *exp;
2102 
2103         for (s = mod->unres; s; s = s->next) {
2104                 const char *basename;
2105                 exp = find_symbol(s->name);
2106                 if (!exp || exp->module == mod)
2107                         continue;
2108                 basename = strrchr(mod->name, '/');
2109                 if (basename)
2110                         basename++;
2111                 else
2112                         basename = mod->name;
2113                 if (!mod->gpl_compatible)
2114                         check_for_gpl_usage(exp->export, basename, exp->name);
2115                 check_for_unused(exp->export, basename, exp->name);
2116         }
2117 }
2118 
2119 /**
2120  * Header for the generated file
2121  **/
2122 static void add_header(struct buffer *b, struct module *mod)
2123 {
2124         buf_printf(b, "#include <linux/module.h>\n");
2125         buf_printf(b, "#include <linux/vermagic.h>\n");
2126         buf_printf(b, "#include <linux/compiler.h>\n");
2127         buf_printf(b, "\n");
2128         buf_printf(b, "MODULE_INFO(vermagic, VERMAGIC_STRING);\n");
2129         buf_printf(b, "\n");
2130         buf_printf(b, "__visible struct module __this_module\n");
2131         buf_printf(b, "__attribute__((section(\".gnu.linkonce.this_module\"))) = {\n");
2132         buf_printf(b, "\t.name = KBUILD_MODNAME,\n");
2133         if (mod->has_init)
2134                 buf_printf(b, "\t.init = init_module,\n");
2135         if (mod->has_cleanup)
2136                 buf_printf(b, "#ifdef CONFIG_MODULE_UNLOAD\n"
2137                               "\t.exit = cleanup_module,\n"
2138                               "#endif\n");
2139         buf_printf(b, "\t.arch = MODULE_ARCH_INIT,\n");
2140         buf_printf(b, "};\n");
2141 }
2142 
2143 static void add_intree_flag(struct buffer *b, int is_intree)
2144 {
2145         if (is_intree)
2146                 buf_printf(b, "\nMODULE_INFO(intree, \"Y\");\n");
2147 }
2148 
2149 static void add_staging_flag(struct buffer *b, const char *name)
2150 {
2151         static const char *staging_dir = "drivers/staging";
2152 
2153         if (strncmp(staging_dir, name, strlen(staging_dir)) == 0)
2154                 buf_printf(b, "\nMODULE_INFO(staging, \"Y\");\n");
2155 }
2156 
2157 /* In kernel, this size is defined in linux/module.h;
2158  * here we use Elf_Addr instead of long for covering cross-compile
2159  */
2160 #define MODULE_NAME_LEN (64 - sizeof(Elf_Addr))
2161 
2162 /**
2163  * Record CRCs for unresolved symbols
2164  **/
2165 static int add_versions(struct buffer *b, struct module *mod)
2166 {
2167         struct symbol *s, *exp;
2168         int err = 0;
2169 
2170         for (s = mod->unres; s; s = s->next) {
2171                 exp = find_symbol(s->name);
2172                 if (!exp || exp->module == mod) {
2173                         if (have_vmlinux && !s->weak) {
2174                                 if (warn_unresolved) {
2175                                         warn("\"%s\" [%s.ko] undefined!\n",
2176                                              s->name, mod->name);
2177                                 } else {
2178                                         merror("\"%s\" [%s.ko] undefined!\n",
2179                                                s->name, mod->name);
2180                                         err = 1;
2181                                 }
2182                         }
2183                         continue;
2184                 }
2185                 s->module = exp->module;
2186                 s->crc_valid = exp->crc_valid;
2187                 s->crc = exp->crc;
2188         }
2189 
2190         if (!modversions)
2191                 return err;
2192 
2193         buf_printf(b, "\n");
2194         buf_printf(b, "static const struct modversion_info ____versions[]\n");
2195         buf_printf(b, "__used\n");
2196         buf_printf(b, "__attribute__((section(\"__versions\"))) = {\n");
2197 
2198         for (s = mod->unres; s; s = s->next) {
2199                 if (!s->module)
2200                         continue;
2201                 if (!s->crc_valid) {
2202                         warn("\"%s\" [%s.ko] has no CRC!\n",
2203                                 s->name, mod->name);
2204                         continue;
2205                 }
2206                 if (strlen(s->name) >= MODULE_NAME_LEN) {
2207                         merror("too long symbol \"%s\" [%s.ko]\n",
2208                                s->name, mod->name);
2209                         err = 1;
2210                         break;
2211                 }
2212                 buf_printf(b, "\t{ %#8x, __VMLINUX_SYMBOL_STR(%s) },\n",
2213                            s->crc, s->name);
2214         }
2215 
2216         buf_printf(b, "};\n");
2217 
2218         return err;
2219 }
2220 
2221 static void add_depends(struct buffer *b, struct module *mod,
2222                         struct module *modules)
2223 {
2224         struct symbol *s;
2225         struct module *m;
2226         int first = 1;
2227 
2228         for (m = modules; m; m = m->next)
2229                 m->seen = is_vmlinux(m->name);
2230 
2231         buf_printf(b, "\n");
2232         buf_printf(b, "static const char __module_depends[]\n");
2233         buf_printf(b, "__used\n");
2234         buf_printf(b, "__attribute__((section(\".modinfo\"))) =\n");
2235         buf_printf(b, "\"depends=");
2236         for (s = mod->unres; s; s = s->next) {
2237                 const char *p;
2238                 if (!s->module)
2239                         continue;
2240 
2241                 if (s->module->seen)
2242                         continue;
2243 
2244                 s->module->seen = 1;
2245                 p = strrchr(s->module->name, '/');
2246                 if (p)
2247                         p++;
2248                 else
2249                         p = s->module->name;
2250                 buf_printf(b, "%s%s", first ? "" : ",", p);
2251                 first = 0;
2252         }
2253         buf_printf(b, "\";\n");
2254 }
2255 
2256 static void add_srcversion(struct buffer *b, struct module *mod)
2257 {
2258         if (mod->srcversion[0]) {
2259                 buf_printf(b, "\n");
2260                 buf_printf(b, "MODULE_INFO(srcversion, \"%s\");\n",
2261                            mod->srcversion);
2262         }
2263 }
2264 
2265 static void write_if_changed(struct buffer *b, const char *fname)
2266 {
2267         char *tmp;
2268         FILE *file;
2269         struct stat st;
2270 
2271         file = fopen(fname, "r");
2272         if (!file)
2273                 goto write;
2274 
2275         if (fstat(fileno(file), &st) < 0)
2276                 goto close_write;
2277 
2278         if (st.st_size != b->pos)
2279                 goto close_write;
2280 
2281         tmp = NOFAIL(malloc(b->pos));
2282         if (fread(tmp, 1, b->pos, file) != b->pos)
2283                 goto free_write;
2284 
2285         if (memcmp(tmp, b->p, b->pos) != 0)
2286                 goto free_write;
2287 
2288         free(tmp);
2289         fclose(file);
2290         return;
2291 
2292  free_write:
2293         free(tmp);
2294  close_write:
2295         fclose(file);
2296  write:
2297         file = fopen(fname, "w");
2298         if (!file) {
2299                 perror(fname);
2300                 exit(1);
2301         }
2302         if (fwrite(b->p, 1, b->pos, file) != b->pos) {
2303                 perror(fname);
2304                 exit(1);
2305         }
2306         fclose(file);
2307 }
2308 
2309 /* parse Module.symvers file. line format:
2310  * 0x12345678<tab>symbol<tab>module[[<tab>export]<tab>something]
2311  **/
2312 static void read_dump(const char *fname, unsigned int kernel)
2313 {
2314         unsigned long size, pos = 0;
2315         void *file = grab_file(fname, &size);
2316         char *line;
2317 
2318         if (!file)
2319                 /* No symbol versions, silently ignore */
2320                 return;
2321 
2322         while ((line = get_next_line(&pos, file, size))) {
2323                 char *symname, *modname, *d, *export, *end;
2324                 unsigned int crc;
2325                 struct module *mod;
2326                 struct symbol *s;
2327 
2328                 if (!(symname = strchr(line, '\t')))
2329                         goto fail;
2330                 *symname++ = '\0';
2331                 if (!(modname = strchr(symname, '\t')))
2332                         goto fail;
2333                 *modname++ = '\0';
2334                 if ((export = strchr(modname, '\t')) != NULL)
2335                         *export++ = '\0';
2336                 if (export && ((end = strchr(export, '\t')) != NULL))
2337                         *end = '\0';
2338                 crc = strtoul(line, &d, 16);
2339                 if (*symname == '\0' || *modname == '\0' || *d != '\0')
2340                         goto fail;
2341                 mod = find_module(modname);
2342                 if (!mod) {
2343                         if (is_vmlinux(modname))
2344                                 have_vmlinux = 1;
2345                         mod = new_module(modname);
2346                         mod->skip = 1;
2347                 }
2348                 s = sym_add_exported(symname, mod, export_no(export));
2349                 s->kernel    = kernel;
2350                 s->preloaded = 1;
2351                 sym_update_crc(symname, mod, crc, export_no(export));
2352         }
2353         release_file(file, size);
2354         return;
2355 fail:
2356         release_file(file, size);
2357         fatal("parse error in symbol dump file\n");
2358 }
2359 
2360 /* For normal builds always dump all symbols.
2361  * For external modules only dump symbols
2362  * that are not read from kernel Module.symvers.
2363  **/
2364 static int dump_sym(struct symbol *sym)
2365 {
2366         if (!external_module)
2367                 return 1;
2368         if (sym->vmlinux || sym->kernel)
2369                 return 0;
2370         return 1;
2371 }
2372 
2373 static void write_dump(const char *fname)
2374 {
2375         struct buffer buf = { };
2376         struct symbol *symbol;
2377         int n;
2378 
2379         for (n = 0; n < SYMBOL_HASH_SIZE ; n++) {
2380                 symbol = symbolhash[n];
2381                 while (symbol) {
2382                         if (dump_sym(symbol))
2383                                 buf_printf(&buf, "0x%08x\t%s\t%s\t%s\n",
2384                                         symbol->crc, symbol->name,
2385                                         symbol->module->name,
2386                                         export_str(symbol->export));
2387                         symbol = symbol->next;
2388                 }
2389         }
2390         write_if_changed(&buf, fname);
2391         free(buf.p);
2392 }
2393 
2394 struct ext_sym_list {
2395         struct ext_sym_list *next;
2396         const char *file;
2397 };
2398 
2399 int main(int argc, char **argv)
2400 {
2401         struct module *mod;
2402         struct buffer buf = { };
2403         char *kernel_read = NULL, *module_read = NULL;
2404         char *dump_write = NULL, *files_source = NULL;
2405         int opt;
2406         int err;
2407         struct ext_sym_list *extsym_iter;
2408         struct ext_sym_list *extsym_start = NULL;
2409 
2410         while ((opt = getopt(argc, argv, "i:I:e:mnsST:o:awM:K:E")) != -1) {
2411                 switch (opt) {
2412                 case 'i':
2413                         kernel_read = optarg;
2414                         break;
2415                 case 'I':
2416                         module_read = optarg;
2417                         external_module = 1;
2418                         break;
2419                 case 'e':
2420                         external_module = 1;
2421                         extsym_iter =
2422                            NOFAIL(malloc(sizeof(*extsym_iter)));
2423                         extsym_iter->next = extsym_start;
2424                         extsym_iter->file = optarg;
2425                         extsym_start = extsym_iter;
2426                         break;
2427                 case 'm':
2428                         modversions = 1;
2429                         break;
2430                 case 'n':
2431                         ignore_missing_files = 1;
2432                         break;
2433                 case 'o':
2434                         dump_write = optarg;
2435                         break;
2436                 case 'a':
2437                         all_versions = 1;
2438                         break;
2439                 case 's':
2440                         vmlinux_section_warnings = 0;
2441                         break;
2442                 case 'S':
2443                         sec_mismatch_verbose = 0;
2444                         break;
2445                 case 'T':
2446                         files_source = optarg;
2447                         break;
2448                 case 'w':
2449                         warn_unresolved = 1;
2450                         break;
2451                 case 'E':
2452                         sec_mismatch_fatal = 1;
2453                         break;
2454                 default:
2455                         exit(1);
2456                 }
2457         }
2458 
2459         if (kernel_read)
2460                 read_dump(kernel_read, 1);
2461         if (module_read)
2462                 read_dump(module_read, 0);
2463         while (extsym_start) {
2464                 read_dump(extsym_start->file, 0);
2465                 extsym_iter = extsym_start->next;
2466                 free(extsym_start);
2467                 extsym_start = extsym_iter;
2468         }
2469 
2470         while (optind < argc)
2471                 read_symbols(argv[optind++]);
2472 
2473         if (files_source)
2474                 read_symbols_from_files(files_source);
2475 
2476         for (mod = modules; mod; mod = mod->next) {
2477                 if (mod->skip)
2478                         continue;
2479                 check_exports(mod);
2480         }
2481 
2482         err = 0;
2483 
2484         for (mod = modules; mod; mod = mod->next) {
2485                 char fname[PATH_MAX];
2486 
2487                 if (mod->skip)
2488                         continue;
2489 
2490                 buf.pos = 0;
2491 
2492                 add_header(&buf, mod);
2493                 add_intree_flag(&buf, !external_module);
2494                 add_staging_flag(&buf, mod->name);
2495                 err |= add_versions(&buf, mod);
2496                 add_depends(&buf, mod, modules);
2497                 add_moddevtable(&buf, mod);
2498                 add_srcversion(&buf, mod);
2499 
2500                 sprintf(fname, "%s.mod.c", mod->name);
2501                 write_if_changed(&buf, fname);
2502         }
2503         if (dump_write)
2504                 write_dump(dump_write);
2505         if (sec_mismatch_count) {
2506                 if (!sec_mismatch_verbose) {
2507                         warn("modpost: Found %d section mismatch(es).\n"
2508                              "To see full details build your kernel with:\n"
2509                              "'make CONFIG_DEBUG_SECTION_MISMATCH=y'\n",
2510                              sec_mismatch_count);
2511                 }
2512                 if (sec_mismatch_fatal) {
2513                         fatal("modpost: Section mismatches detected.\n"
2514                               "Set CONFIG_SECTION_MISMATCH_WARN_ONLY=y to allow them.\n");
2515                 }
2516         }
2517         free(buf.p);
2518 
2519         return err;
2520 }
2521 

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