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modpost.c

/* Postprocess module symbol versions
 *
 * Copyright 2003       Kai Germaschewski
 * Copyright 2002-2004  Rusty Russell, IBM Corporation
 * Copyright 2006       Sam Ravnborg
 * Based in part on module-init-tools/depmod.c,file2alias
 *
 * This software may be used and distributed according to the terms
 * of the GNU General Public License, incorporated herein by reference.
 *
 * Usage: modpost vmlinux module1.o module2.o ...
 */

#include <ctype.h>
#include "modpost.h"
#include "../../include/linux/license.h"

/* Are we using CONFIG_MODVERSIONS? */
int modversions = 0;
/* Warn about undefined symbols? (do so if we have vmlinux) */
int have_vmlinux = 0;
/* Is CONFIG_MODULE_SRCVERSION_ALL set? */
static int all_versions = 0;
/* If we are modposting external module set to 1 */
static int external_module = 0;
/* Warn about section mismatch in vmlinux if set to 1 */
static int vmlinux_section_warnings = 1;
/* Only warn about unresolved symbols */
static int warn_unresolved = 0;
/* How a symbol is exported */
enum export {
      export_plain,      export_unused,     export_gpl,
      export_unused_gpl, export_gpl_future, export_unknown
};

void fatal(const char *fmt, ...)
{
      va_list arglist;

      fprintf(stderr, "FATAL: ");

      va_start(arglist, fmt);
      vfprintf(stderr, fmt, arglist);
      va_end(arglist);

      exit(1);
}

void warn(const char *fmt, ...)
{
      va_list arglist;

      fprintf(stderr, "WARNING: ");

      va_start(arglist, fmt);
      vfprintf(stderr, fmt, arglist);
      va_end(arglist);
}

void merror(const char *fmt, ...)
{
      va_list arglist;

      fprintf(stderr, "ERROR: ");

      va_start(arglist, fmt);
      vfprintf(stderr, fmt, arglist);
      va_end(arglist);
}

static int is_vmlinux(const char *modname)
{
      const char *myname;

      if ((myname = strrchr(modname, '/')))
            myname++;
      else
            myname = modname;

      return (strcmp(myname, "vmlinux") == 0) ||
             (strcmp(myname, "vmlinux.o") == 0);
}

void *do_nofail(void *ptr, const char *expr)
{
      if (!ptr) {
            fatal("modpost: Memory allocation failure: %s.\n", expr);
      }
      return ptr;
}

/* A list of all modules we processed */

static struct module *modules;

static struct module *find_module(char *modname)
{
      struct module *mod;

      for (mod = modules; mod; mod = mod->next)
            if (strcmp(mod->name, modname) == 0)
                  break;
      return mod;
}

static struct module *new_module(char *modname)
{
      struct module *mod;
      char *p, *s;

      mod = NOFAIL(malloc(sizeof(*mod)));
      memset(mod, 0, sizeof(*mod));
      p = NOFAIL(strdup(modname));

      /* strip trailing .o */
      if ((s = strrchr(p, '.')) != NULL)
            if (strcmp(s, ".o") == 0)
                  *s = '\0';

      /* add to list */
      mod->name = p;
      mod->gpl_compatible = -1;
      mod->next = modules;
      modules = mod;

      return mod;
}

/* A hash of all exported symbols,
 * struct symbol is also used for lists of unresolved symbols */

#define SYMBOL_HASH_SIZE 1024

struct symbol {
      struct symbol *next;
      struct module *module;
      unsigned int crc;
      int crc_valid;
      unsigned int weak:1;
      unsigned int vmlinux:1;    /* 1 if symbol is defined in vmlinux */
      unsigned int kernel:1;     /* 1 if symbol is from kernel
                            *  (only for external modules) **/
      unsigned int preloaded:1;  /* 1 if symbol from Module.symvers */
      enum export  export;       /* Type of export */
      char name[0];
};

static struct symbol *symbolhash[SYMBOL_HASH_SIZE];

/* This is based on the hash agorithm from gdbm, via tdb */
static inline unsigned int tdb_hash(const char *name)
{
      unsigned value;   /* Used to compute the hash value.  */
      unsigned   i;     /* Used to cycle through random values. */

      /* Set the initial value from the key size. */
      for (value = 0x238F13AF * strlen(name), i=0; name[i]; i++)
            value = (value + (((unsigned char *)name)[i] << (i*5 % 24)));

      return (1103515243 * value + 12345);
}

/**
 * Allocate a new symbols for use in the hash of exported symbols or
 * the list of unresolved symbols per module
 **/
static struct symbol *alloc_symbol(const char *name, unsigned int weak,
                           struct symbol *next)
{
      struct symbol *s = NOFAIL(malloc(sizeof(*s) + strlen(name) + 1));

      memset(s, 0, sizeof(*s));
      strcpy(s->name, name);
      s->weak = weak;
      s->next = next;
      return s;
}

/* For the hash of exported symbols */
static struct symbol *new_symbol(const char *name, struct module *module,
                         enum export export)
{
      unsigned int hash;
      struct symbol *new;

      hash = tdb_hash(name) % SYMBOL_HASH_SIZE;
      new = symbolhash[hash] = alloc_symbol(name, 0, symbolhash[hash]);
      new->module = module;
      new->export = export;
      return new;
}

static struct symbol *find_symbol(const char *name)
{
      struct symbol *s;

      /* For our purposes, .foo matches foo.  PPC64 needs this. */
      if (name[0] == '.')
            name++;

      for (s = symbolhash[tdb_hash(name) % SYMBOL_HASH_SIZE]; s; s=s->next) {
            if (strcmp(s->name, name) == 0)
                  return s;
      }
      return NULL;
}

static struct {
      const char *str;
      enum export export;
} export_list[] = {
      { .str = "EXPORT_SYMBOL",            .export = export_plain },
      { .str = "EXPORT_UNUSED_SYMBOL",     .export = export_unused },
      { .str = "EXPORT_SYMBOL_GPL",        .export = export_gpl },
      { .str = "EXPORT_UNUSED_SYMBOL_GPL", .export = export_unused_gpl },
      { .str = "EXPORT_SYMBOL_GPL_FUTURE", .export = export_gpl_future },
      { .str = "(unknown)",                .export = export_unknown },
};


static const char *export_str(enum export ex)
{
      return export_list[ex].str;
}

static enum export export_no(const char * s)
{
      int i;
      if (!s)
            return export_unknown;
      for (i = 0; export_list[i].export != export_unknown; i++) {
            if (strcmp(export_list[i].str, s) == 0)
                  return export_list[i].export;
      }
      return export_unknown;
}

static enum export export_from_sec(struct elf_info *elf, Elf_Section sec)
{
      if (sec == elf->export_sec)
            return export_plain;
      else if (sec == elf->export_unused_sec)
            return export_unused;
      else if (sec == elf->export_gpl_sec)
            return export_gpl;
      else if (sec == elf->export_unused_gpl_sec)
            return export_unused_gpl;
      else if (sec == elf->export_gpl_future_sec)
            return export_gpl_future;
      else
            return export_unknown;
}

/**
 * Add an exported symbol - it may have already been added without a
 * CRC, in this case just update the CRC
 **/
static struct symbol *sym_add_exported(const char *name, struct module *mod,
                               enum export export)
{
      struct symbol *s = find_symbol(name);

      if (!s) {
            s = new_symbol(name, mod, export);
      } else {
            if (!s->preloaded) {
                  warn("%s: '%s' exported twice. Previous export "
                       "was in %s%s\n", mod->name, name,
                       s->module->name,
                       is_vmlinux(s->module->name) ?"":".ko");
            } else {
                  /* In case Modules.symvers was out of date */
                  s->module = mod;
            }
      }
      s->preloaded = 0;
      s->vmlinux   = is_vmlinux(mod->name);
      s->kernel    = 0;
      s->export    = export;
      return s;
}

static void sym_update_crc(const char *name, struct module *mod,
                     unsigned int crc, enum export export)
{
      struct symbol *s = find_symbol(name);

      if (!s)
            s = new_symbol(name, mod, export);
      s->crc = crc;
      s->crc_valid = 1;
}

void *grab_file(const char *filename, unsigned long *size)
{
      struct stat st;
      void *map;
      int fd;

      fd = open(filename, O_RDONLY);
      if (fd < 0 || fstat(fd, &st) != 0)
            return NULL;

      *size = st.st_size;
      map = mmap(NULL, *size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
      close(fd);

      if (map == MAP_FAILED)
            return NULL;
      return map;
}

/**
  * Return a copy of the next line in a mmap'ed file.
  * spaces in the beginning of the line is trimmed away.
  * Return a pointer to a static buffer.
  **/
char* get_next_line(unsigned long *pos, void *file, unsigned long size)
{
      static char line[4096];
      int skip = 1;
      size_t len = 0;
      signed char *p = (signed char *)file + *pos;
      char *s = line;

      for (; *pos < size ; (*pos)++)
      {
            if (skip && isspace(*p)) {
                  p++;
                  continue;
            }
            skip = 0;
            if (*p != '\n' && (*pos < size)) {
                  len++;
                  *s++ = *p++;
                  if (len > 4095)
                        break; /* Too long, stop */
            } else {
                  /* End of string */
                  *s = '\0';
                  return line;
            }
      }
      /* End of buffer */
      return NULL;
}

void release_file(void *file, unsigned long size)
{
      munmap(file, size);
}

static int parse_elf(struct elf_info *info, const char *filename)
{
      unsigned int i;
      Elf_Ehdr *hdr;
      Elf_Shdr *sechdrs;
      Elf_Sym  *sym;

      hdr = grab_file(filename, &info->size);
      if (!hdr) {
            perror(filename);
            exit(1);
      }
      info->hdr = hdr;
      if (info->size < sizeof(*hdr)) {
            /* file too small, assume this is an empty .o file */
            return 0;
      }
      /* Is this a valid ELF file? */
      if ((hdr->e_ident[EI_MAG0] != ELFMAG0) ||
          (hdr->e_ident[EI_MAG1] != ELFMAG1) ||
          (hdr->e_ident[EI_MAG2] != ELFMAG2) ||
          (hdr->e_ident[EI_MAG3] != ELFMAG3)) {
            /* Not an ELF file - silently ignore it */
            return 0;
      }
      /* Fix endianness in ELF header */
      hdr->e_shoff    = TO_NATIVE(hdr->e_shoff);
      hdr->e_shstrndx = TO_NATIVE(hdr->e_shstrndx);
      hdr->e_shnum    = TO_NATIVE(hdr->e_shnum);
      hdr->e_machine  = TO_NATIVE(hdr->e_machine);
      hdr->e_type     = TO_NATIVE(hdr->e_type);
      sechdrs = (void *)hdr + hdr->e_shoff;
      info->sechdrs = sechdrs;

      /* Check if file offset is correct */
      if (hdr->e_shoff > info->size) {
            fatal("section header offset=%u in file '%s' is bigger then filesize=%lu\n", hdr->e_shoff, filename, info->size);
            return 0;
      }

      /* Fix endianness in section headers */
      for (i = 0; i < hdr->e_shnum; i++) {
            sechdrs[i].sh_type   = TO_NATIVE(sechdrs[i].sh_type);
            sechdrs[i].sh_offset = TO_NATIVE(sechdrs[i].sh_offset);
            sechdrs[i].sh_size   = TO_NATIVE(sechdrs[i].sh_size);
            sechdrs[i].sh_link   = TO_NATIVE(sechdrs[i].sh_link);
            sechdrs[i].sh_name   = TO_NATIVE(sechdrs[i].sh_name);
            sechdrs[i].sh_info   = TO_NATIVE(sechdrs[i].sh_info);
            sechdrs[i].sh_addr   = TO_NATIVE(sechdrs[i].sh_addr);
      }
      /* Find symbol table. */
      for (i = 1; i < hdr->e_shnum; i++) {
            const char *secstrings
                  = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
            const char *secname;

            if (sechdrs[i].sh_offset > info->size) {
                  fatal("%s is truncated. sechdrs[i].sh_offset=%u > sizeof(*hrd)=%ul\n", filename, (unsigned int)sechdrs[i].sh_offset, sizeof(*hdr));
                  return 0;
            }
            secname = secstrings + sechdrs[i].sh_name;
            if (strcmp(secname, ".modinfo") == 0) {
                  info->modinfo = (void *)hdr + sechdrs[i].sh_offset;
                  info->modinfo_len = sechdrs[i].sh_size;
            } else if (strcmp(secname, "__ksymtab") == 0)
                  info->export_sec = i;
            else if (strcmp(secname, "__ksymtab_unused") == 0)
                  info->export_unused_sec = i;
            else if (strcmp(secname, "__ksymtab_gpl") == 0)
                  info->export_gpl_sec = i;
            else if (strcmp(secname, "__ksymtab_unused_gpl") == 0)
                  info->export_unused_gpl_sec = i;
            else if (strcmp(secname, "__ksymtab_gpl_future") == 0)
                  info->export_gpl_future_sec = i;

            if (sechdrs[i].sh_type != SHT_SYMTAB)
                  continue;

            info->symtab_start = (void *)hdr + sechdrs[i].sh_offset;
            info->symtab_stop  = (void *)hdr + sechdrs[i].sh_offset
                                           + sechdrs[i].sh_size;
            info->strtab       = (void *)hdr +
                               sechdrs[sechdrs[i].sh_link].sh_offset;
      }
      if (!info->symtab_start) {
            fatal("%s has no symtab?\n", filename);
      }
      /* Fix endianness in symbols */
      for (sym = info->symtab_start; sym < info->symtab_stop; sym++) {
            sym->st_shndx = TO_NATIVE(sym->st_shndx);
            sym->st_name  = TO_NATIVE(sym->st_name);
            sym->st_value = TO_NATIVE(sym->st_value);
            sym->st_size  = TO_NATIVE(sym->st_size);
      }
      return 1;
}

static void parse_elf_finish(struct elf_info *info)
{
      release_file(info->hdr, info->size);
}

#define CRC_PFX     MODULE_SYMBOL_PREFIX "__crc_"
#define KSYMTAB_PFX MODULE_SYMBOL_PREFIX "__ksymtab_"

static void handle_modversions(struct module *mod, struct elf_info *info,
                         Elf_Sym *sym, const char *symname)
{
      unsigned int crc;
      enum export export = export_from_sec(info, sym->st_shndx);

      switch (sym->st_shndx) {
      case SHN_COMMON:
            warn("\"%s\" [%s] is COMMON symbol\n", symname, mod->name);
            break;
      case SHN_ABS:
            /* CRC'd symbol */
            if (memcmp(symname, CRC_PFX, strlen(CRC_PFX)) == 0) {
                  crc = (unsigned int) sym->st_value;
                  sym_update_crc(symname + strlen(CRC_PFX), mod, crc,
                              export);
            }
            break;
      case SHN_UNDEF:
            /* undefined symbol */
            if (ELF_ST_BIND(sym->st_info) != STB_GLOBAL &&
                ELF_ST_BIND(sym->st_info) != STB_WEAK)
                  break;
            /* ignore global offset table */
            if (strcmp(symname, "_GLOBAL_OFFSET_TABLE_") == 0)
                  break;
            /* ignore __this_module, it will be resolved shortly */
            if (strcmp(symname, MODULE_SYMBOL_PREFIX "__this_module") == 0)
                  break;
/* cope with newer glibc (2.3.4 or higher) STT_ definition in elf.h */
#if defined(STT_REGISTER) || defined(STT_SPARC_REGISTER)
/* add compatibility with older glibc */
#ifndef STT_SPARC_REGISTER
#define STT_SPARC_REGISTER STT_REGISTER
#endif
            if (info->hdr->e_machine == EM_SPARC ||
                info->hdr->e_machine == EM_SPARCV9) {
                  /* Ignore register directives. */
                  if (ELF_ST_TYPE(sym->st_info) == STT_SPARC_REGISTER)
                        break;
                  if (symname[0] == '.') {
                        char *munged = strdup(symname);
                        munged[0] = '_';
                        munged[1] = toupper(munged[1]);
                        symname = munged;
                  }
            }
#endif

            if (memcmp(symname, MODULE_SYMBOL_PREFIX,
                     strlen(MODULE_SYMBOL_PREFIX)) == 0)
                  mod->unres = alloc_symbol(symname +
                                      strlen(MODULE_SYMBOL_PREFIX),
                                      ELF_ST_BIND(sym->st_info) == STB_WEAK,
                                      mod->unres);
            break;
      default:
            /* All exported symbols */
            if (memcmp(symname, KSYMTAB_PFX, strlen(KSYMTAB_PFX)) == 0) {
                  sym_add_exported(symname + strlen(KSYMTAB_PFX), mod,
                              export);
            }
            if (strcmp(symname, MODULE_SYMBOL_PREFIX "init_module") == 0)
                  mod->has_init = 1;
            if (strcmp(symname, MODULE_SYMBOL_PREFIX "cleanup_module") == 0)
                  mod->has_cleanup = 1;
            break;
      }
}

/**
 * Parse tag=value strings from .modinfo section
 **/
static char *next_string(char *string, unsigned long *secsize)
{
      /* Skip non-zero chars */
      while (string[0]) {
            string++;
            if ((*secsize)-- <= 1)
                  return NULL;
      }

      /* Skip any zero padding. */
      while (!string[0]) {
            string++;
            if ((*secsize)-- <= 1)
                  return NULL;
      }
      return string;
}

static char *get_next_modinfo(void *modinfo, unsigned long modinfo_len,
                        const char *tag, char *info)
{
      char *p;
      unsigned int taglen = strlen(tag);
      unsigned long size = modinfo_len;

      if (info) {
            size -= info - (char *)modinfo;
            modinfo = next_string(info, &size);
      }

      for (p = modinfo; p; p = next_string(p, &size)) {
            if (strncmp(p, tag, taglen) == 0 && p[taglen] == '=')
                  return p + taglen + 1;
      }
      return NULL;
}

static char *get_modinfo(void *modinfo, unsigned long modinfo_len,
                   const char *tag)

{
      return get_next_modinfo(modinfo, modinfo_len, tag, NULL);
}

/**
 * Test if string s ends in string sub
 * return 0 if match
 **/
static int strrcmp(const char *s, const char *sub)
{
        int slen, sublen;

      if (!s || !sub)
            return 1;

      slen = strlen(s);
        sublen = strlen(sub);

      if ((slen == 0) || (sublen == 0))
            return 1;

        if (sublen > slen)
                return 1;

        return memcmp(s + slen - sublen, sub, sublen);
}

/*
 * Functions used only during module init is marked __init and is stored in
 * a .init.text section. Likewise data is marked __initdata and stored in
 * a .init.data section.
 * If this section is one of these sections return 1
 * See include/linux/init.h for the details
 */
static int init_section(const char *name)
{
      if (strcmp(name, ".init") == 0)
            return 1;
      if (strncmp(name, ".init.", strlen(".init.")) == 0)
            return 1;
      return 0;
}

/*
 * Functions used only during module exit is marked __exit and is stored in
 * a .exit.text section. Likewise data is marked __exitdata and stored in
 * a .exit.data section.
 * If this section is one of these sections return 1
 * See include/linux/init.h for the details
 **/
static int exit_section(const char *name)
{
      if (strcmp(name, ".exit.text") == 0)
            return 1;
      if (strcmp(name, ".exit.data") == 0)
            return 1;
      return 0;

}

/*
 * Data sections are named like this:
 * .data | .data.rel | .data.rel.*
 * Return 1 if the specified section is a data section
 */
static int data_section(const char *name)
{
      if ((strcmp(name, ".data") == 0) ||
          (strcmp(name, ".data.rel") == 0) ||
          (strncmp(name, ".data.rel.", strlen(".data.rel.")) == 0))
            return 1;
      else
            return 0;
}

/**
 * Whitelist to allow certain references to pass with no warning.
 *
 * Pattern 0:
 *   Do not warn if funtion/data are marked with __init_refok/__initdata_refok.
 *   The pattern is identified by:
 *   fromsec = .text.init.refok* | .data.init.refok*
 *
 * Pattern 1:
 *   If a module parameter is declared __initdata and permissions=0
 *   then this is legal despite the warning generated.
 *   We cannot see value of permissions here, so just ignore
 *   this pattern.
 *   The pattern is identified by:
 *   tosec   = .init.data
 *   fromsec = .data*
 *   atsym   =__param*
 *
 * Pattern 2:
 *   Many drivers utilise a *driver container with references to
 *   add, remove, probe functions etc.
 *   These functions may often be marked __init and we do not want to
 *   warn here.
 *   the pattern is identified by:
 *   tosec   = init or exit section
 *   fromsec = data section
 *   atsym = *driver, *_template, *_sht, *_ops, *_probe, *probe_one, *_console, *_timer
 *
 * Pattern 3:
 *   Whitelist all refereces from .text.head to .init.data
 *   Whitelist all refereces from .text.head to .init.text
 *
 * Pattern 4:
 *   Some symbols belong to init section but still it is ok to reference
 *   these from non-init sections as these symbols don't have any memory
 *   allocated for them and symbol address and value are same. So even
 *   if init section is freed, its ok to reference those symbols.
 *   For ex. symbols marking the init section boundaries.
 *   This pattern is identified by
 *   refsymname = __init_begin, _sinittext, _einittext
 *
 * Pattern 5:
 *   Xtensa uses literal sections for constants that are accessed PC-relative.
 *   Literal sections may safely reference their text sections.
 *   (Note that the name for the literal section omits any trailing '.text')
 *   tosec = <section>[.text]
 *   fromsec = <section>.literal
 **/
static int secref_whitelist(const char *modname, const char *tosec,
                      const char *fromsec, const char *atsym,
                      const char *refsymname)
{
      int len;
      const char **s;
      const char *pat2sym[] = {
            "driver",
            "_template", /* scsi uses *_template a lot */
            "_timer",    /* arm uses ops structures named _timer a lot */
            "_sht",      /* scsi also used *_sht to some extent */
            "_ops",
            "_probe",
            "_probe_one",
            "_console",
            NULL
      };

      const char *pat3refsym[] = {
            "__init_begin",
            "_sinittext",
            "_einittext",
            NULL
      };

      /* Check for pattern 0 */
      if ((strncmp(fromsec, ".text.init.refok", strlen(".text.init.refok")) == 0) ||
          (strncmp(fromsec, ".exit.text.refok", strlen(".exit.text.refok")) == 0) ||
          (strncmp(fromsec, ".data.init.refok", strlen(".data.init.refok")) == 0))
            return 1;

      /* Check for pattern 1 */
      if ((strcmp(tosec, ".init.data") == 0) &&
          (strncmp(fromsec, ".data", strlen(".data")) == 0) &&
          (strncmp(atsym, "__param", strlen("__param")) == 0))
            return 1;

      /* Check for pattern 2 */
      if ((init_section(tosec) || exit_section(tosec)) && data_section(fromsec))
            for (s = pat2sym; *s; s++)
                  if (strrcmp(atsym, *s) == 0)
                        return 1;

      /* Check for pattern 3 */
      if ((strcmp(fromsec, ".text.head") == 0) &&
            ((strcmp(tosec, ".init.data") == 0) ||
            (strcmp(tosec, ".init.text") == 0)))
      return 1;

      /* Check for pattern 4 */
      for (s = pat3refsym; *s; s++)
            if (strcmp(refsymname, *s) == 0)
                  return 1;

      /* Check for pattern 5 */
      if (strrcmp(tosec, ".text") == 0)
            len = strlen(tosec) - strlen(".text");
      else
            len = strlen(tosec);
      if ((strncmp(tosec, fromsec, len) == 0) && (strlen(fromsec) > len) &&
          (strcmp(fromsec + len, ".literal") == 0))
            return 1;

      return 0;
}

/**
 * Find symbol based on relocation record info.
 * In some cases the symbol supplied is a valid symbol so
 * return refsym. If st_name != 0 we assume this is a valid symbol.
 * In other cases the symbol needs to be looked up in the symbol table
 * based on section and address.
 *  **/
static Elf_Sym *find_elf_symbol(struct elf_info *elf, Elf_Addr addr,
                        Elf_Sym *relsym)
{
      Elf_Sym *sym;

      if (relsym->st_name != 0)
            return relsym;
      for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) {
            if (sym->st_shndx != relsym->st_shndx)
                  continue;
            if (ELF_ST_TYPE(sym->st_info) == STT_SECTION)
                  continue;
            if (sym->st_value == addr)
                  return sym;
      }
      return NULL;
}

static inline int is_arm_mapping_symbol(const char *str)
{
      return str[0] == '$' && strchr("atd", str[1])
             && (str[2] == '\0' || str[2] == '.');
}

/*
 * If there's no name there, ignore it; likewise, ignore it if it's
 * one of the magic symbols emitted used by current ARM tools.
 *
 * Otherwise if find_symbols_between() returns those symbols, they'll
 * fail the whitelist tests and cause lots of false alarms ... fixable
 * only by merging __exit and __init sections into __text, bloating
 * the kernel (which is especially evil on embedded platforms).
 */
static inline int is_valid_name(struct elf_info *elf, Elf_Sym *sym)
{
      const char *name = elf->strtab + sym->st_name;

      if (!name || !strlen(name))
            return 0;
      return !is_arm_mapping_symbol(name);
}

/*
 * Find symbols before or equal addr and after addr - in the section sec.
 * If we find two symbols with equal offset prefer one with a valid name.
 * The ELF format may have a better way to detect what type of symbol
 * it is, but this works for now.
 **/
static void find_symbols_between(struct elf_info *elf, Elf_Addr addr,
                         const char *sec,
                           Elf_Sym **before, Elf_Sym **after)
{
      Elf_Sym *sym;
      Elf_Ehdr *hdr = elf->hdr;
      Elf_Addr beforediff = ~0;
      Elf_Addr afterdiff = ~0;
      const char *secstrings = (void *)hdr +
                         elf->sechdrs[hdr->e_shstrndx].sh_offset;

      *before = NULL;
      *after = NULL;

      for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) {
            const char *symsec;

            if (sym->st_shndx >= SHN_LORESERVE)
                  continue;
            symsec = secstrings + elf->sechdrs[sym->st_shndx].sh_name;
            if (strcmp(symsec, sec) != 0)
                  continue;
            if (!is_valid_name(elf, sym))
                  continue;
            if (sym->st_value <= addr) {
                  if ((addr - sym->st_value) < beforediff) {
                        beforediff = addr - sym->st_value;
                        *before = sym;
                  }
                  else if ((addr - sym->st_value) == beforediff) {
                        *before = sym;
                  }
            }
            else
            {
                  if ((sym->st_value - addr) < afterdiff) {
                        afterdiff = sym->st_value - addr;
                        *after = sym;
                  }
                  else if ((sym->st_value - addr) == afterdiff) {
                        *after = sym;
                  }
            }
      }
}

/**
 * Print a warning about a section mismatch.
 * Try to find symbols near it so user can find it.
 * Check whitelist before warning - it may be a false positive.
 **/
static void warn_sec_mismatch(const char *modname, const char *fromsec,
                        struct elf_info *elf, Elf_Sym *sym, Elf_Rela r)
{
      const char *refsymname = "";
      Elf_Sym *before, *after;
      Elf_Sym *refsym;
      Elf_Ehdr *hdr = elf->hdr;
      Elf_Shdr *sechdrs = elf->sechdrs;
      const char *secstrings = (void *)hdr +
                         sechdrs[hdr->e_shstrndx].sh_offset;
      const char *secname = secstrings + sechdrs[sym->st_shndx].sh_name;

      find_symbols_between(elf, r.r_offset, fromsec, &before, &after);

      refsym = find_elf_symbol(elf, r.r_addend, sym);
      if (refsym && strlen(elf->strtab + refsym->st_name))
            refsymname = elf->strtab + refsym->st_name;

      /* check whitelist - we may ignore it */
      if (secref_whitelist(modname, secname, fromsec,
                       before ? elf->strtab + before->st_name : "",
                           refsymname))
            return;

      if (before && after) {
            warn("%s(%s+0x%llx): Section mismatch: reference to %s:%s "
                 "(between '%s' and '%s')\n",
                 modname, fromsec, (unsigned long long)r.r_offset,
                 secname, refsymname,
                 elf->strtab + before->st_name,
                 elf->strtab + after->st_name);
      } else if (before) {
            warn("%s(%s+0x%llx): Section mismatch: reference to %s:%s "
                 "(after '%s')\n",
                 modname, fromsec, (unsigned long long)r.r_offset,
                 secname, refsymname,
                 elf->strtab + before->st_name);
      } else if (after) {
            warn("%s(%s+0x%llx): Section mismatch: reference to %s:%s "
                 "before '%s' (at offset -0x%llx)\n",
                 modname, fromsec, (unsigned long long)r.r_offset,
                 secname, refsymname,
                 elf->strtab + after->st_name);
      } else {
            warn("%s(%s+0x%llx): Section mismatch: reference to %s:%s\n",
                 modname, fromsec, (unsigned long long)r.r_offset,
                 secname, refsymname);
      }
}

static unsigned int *reloc_location(struct elf_info *elf,
                                 int rsection, Elf_Rela *r)
{
      Elf_Shdr *sechdrs = elf->sechdrs;
      int section = sechdrs[rsection].sh_info;

      return (void *)elf->hdr + sechdrs[section].sh_offset +
            (r->r_offset - sechdrs[section].sh_addr);
}

static int addend_386_rel(struct elf_info *elf, int rsection, Elf_Rela *r)
{
      unsigned int r_typ = ELF_R_TYPE(r->r_info);
      unsigned int *location = reloc_location(elf, rsection, r);

      switch (r_typ) {
      case R_386_32:
            r->r_addend = TO_NATIVE(*location);
            break;
      case R_386_PC32:
            r->r_addend = TO_NATIVE(*location) + 4;
            /* For CONFIG_RELOCATABLE=y */
            if (elf->hdr->e_type == ET_EXEC)
                  r->r_addend += r->r_offset;
            break;
      }
      return 0;
}

static int addend_arm_rel(struct elf_info *elf, int rsection, Elf_Rela *r)
{
      unsigned int r_typ = ELF_R_TYPE(r->r_info);

      switch (r_typ) {
      case R_ARM_ABS32:
            /* From ARM ABI: (S + A) | T */
            r->r_addend = (int)(long)(elf->symtab_start + ELF_R_SYM(r->r_info));
            break;
      case R_ARM_PC24:
            /* From ARM ABI: ((S + A) | T) - P */
            r->r_addend = (int)(long)(elf->hdr + elf->sechdrs[rsection].sh_offset +
                                      (r->r_offset - elf->sechdrs[rsection].sh_addr));
            break;
      default:
            return 1;
      }
      return 0;
}

static int addend_mips_rel(struct elf_info *elf, int rsection, Elf_Rela *r)
{
      unsigned int r_typ = ELF_R_TYPE(r->r_info);
      unsigned int *location = reloc_location(elf, rsection, r);
      unsigned int inst;

      if (r_typ == R_MIPS_HI16)
            return 1;   /* skip this */
      inst = TO_NATIVE(*location);
      switch (r_typ) {
      case R_MIPS_LO16:
            r->r_addend = inst & 0xffff;
            break;
      case R_MIPS_26:
            r->r_addend = (inst & 0x03ffffff) << 2;
            break;
      case R_MIPS_32:
            r->r_addend = inst;
            break;
      }
      return 0;
}

/**
 * A module includes a number of sections that are discarded
 * either when loaded or when used as built-in.
 * For loaded modules all functions marked __init and all data
 * marked __initdata will be discarded when the module has been intialized.
 * Likewise for modules used built-in the sections marked __exit
 * are discarded because __exit marked function are supposed to be called
 * only when a moduel is unloaded which never happes for built-in modules.
 * The check_sec_ref() function traverses all relocation records
 * to find all references to a section that reference a section that will
 * be discarded and warns about it.
 **/
static void check_sec_ref(struct module *mod, const char *modname,
                    struct elf_info *elf,
                    int section(const char*),
                    int section_ref_ok(const char *))
{
      int i;
      Elf_Sym  *sym;
      Elf_Ehdr *hdr = elf->hdr;
      Elf_Shdr *sechdrs = elf->sechdrs;
      const char *secstrings = (void *)hdr +
                         sechdrs[hdr->e_shstrndx].sh_offset;

      /* Walk through all sections */
      for (i = 0; i < hdr->e_shnum; i++) {
            const char *name = secstrings + sechdrs[i].sh_name;
            const char *secname;
            Elf_Rela r;
            unsigned int r_sym;
            /* We want to process only relocation sections and not .init */
            if (sechdrs[i].sh_type == SHT_RELA) {
                  Elf_Rela *rela;
                  Elf_Rela *start = (void *)hdr + sechdrs[i].sh_offset;
                  Elf_Rela *stop  = (void*)start + sechdrs[i].sh_size;
                  name += strlen(".rela");
                  if (section_ref_ok(name))
                        continue;

                  for (rela = start; rela < stop; rela++) {
                        r.r_offset = TO_NATIVE(rela->r_offset);
#if KERNEL_ELFCLASS == ELFCLASS64
                        if (hdr->e_machine == EM_MIPS) {
                              unsigned int r_typ;
                              r_sym = ELF64_MIPS_R_SYM(rela->r_info);
                              r_sym = TO_NATIVE(r_sym);
                              r_typ = ELF64_MIPS_R_TYPE(rela->r_info);
                              r.r_info = ELF64_R_INFO(r_sym, r_typ);
                        } else {
                              r.r_info = TO_NATIVE(rela->r_info);
                              r_sym = ELF_R_SYM(r.r_info);
                        }
#else
                        r.r_info = TO_NATIVE(rela->r_info);
                        r_sym = ELF_R_SYM(r.r_info);
#endif
                        r.r_addend = TO_NATIVE(rela->r_addend);
                        sym = elf->symtab_start + r_sym;
                        /* Skip special sections */
                        if (sym->st_shndx >= SHN_LORESERVE)
                              continue;

                        secname = secstrings +
                              sechdrs[sym->st_shndx].sh_name;
                        if (section(secname))
                              warn_sec_mismatch(modname, name,
                                            elf, sym, r);
                  }
            } else if (sechdrs[i].sh_type == SHT_REL) {
                  Elf_Rel *rel;
                  Elf_Rel *start = (void *)hdr + sechdrs[i].sh_offset;
                  Elf_Rel *stop  = (void*)start + sechdrs[i].sh_size;
                  name += strlen(".rel");
                  if (section_ref_ok(name))
                        continue;

                  for (rel = start; rel < stop; rel++) {
                        r.r_offset = TO_NATIVE(rel->r_offset);
#if KERNEL_ELFCLASS == ELFCLASS64
                        if (hdr->e_machine == EM_MIPS) {
                              unsigned int r_typ;
                              r_sym = ELF64_MIPS_R_SYM(rel->r_info);
                              r_sym = TO_NATIVE(r_sym);
                              r_typ = ELF64_MIPS_R_TYPE(rel->r_info);
                              r.r_info = ELF64_R_INFO(r_sym, r_typ);
                        } else {
                              r.r_info = TO_NATIVE(rel->r_info);
                              r_sym = ELF_R_SYM(r.r_info);
                        }
#else
                        r.r_info = TO_NATIVE(rel->r_info);
                        r_sym = ELF_R_SYM(r.r_info);
#endif
                        r.r_addend = 0;
                        switch (hdr->e_machine) {
                        case EM_386:
                              if (addend_386_rel(elf, i, &r))
                                    continue;
                              break;
                        case EM_ARM:
                              if(addend_arm_rel(elf, i, &r))
                                    continue;
                              break;
                        case EM_MIPS:
                              if (addend_mips_rel(elf, i, &r))
                                    continue;
                              break;
                        }
                        sym = elf->symtab_start + r_sym;
                        /* Skip special sections */
                        if (sym->st_shndx >= SHN_LORESERVE)
                              continue;

                        secname = secstrings +
                              sechdrs[sym->st_shndx].sh_name;
                        if (section(secname))
                              warn_sec_mismatch(modname, name,
                                            elf, sym, r);
                  }
            }
      }
}

/*
 * Identify sections from which references to either a
 * .init or a .exit section is OK.
 *
 * [OPD] Keith Ownes <kaos@sgi.com> commented:
 * For our future {in}sanity, add a comment that this is the ppc .opd
 * section, not the ia64 .opd section.
 * ia64 .opd should not point to discarded sections.
 * [.rodata] like for .init.text we ignore .rodata references -same reason
 */
static int initexit_section_ref_ok(const char *name)
{
      const char **s;
      /* Absolute section names */
      const char *namelist1[] = {
            "__bug_table",          /* used by powerpc for BUG() */
            "__ex_table",
            ".altinstructions",
            ".cranges",       /* used by sh64 */
            ".fixup",
            ".machvec",       /* ia64 + powerpc uses these */
            ".machine.desc",
            ".opd",                 /* See comment [OPD] */
            "__dbe_table",
            ".parainstructions",
            ".pdr",
            ".plt",                 /* seen on ARCH=um build on x86_64. Harmless */
            ".smp_locks",
            ".stab",
            ".m68k_fixup",
            ".xt.prop",       /* xtensa informational section */
            ".xt.lit",        /* xtensa informational section */
            NULL
      };
      /* Start of section names */
      const char *namelist2[] = {
            ".debug",
            ".eh_frame",
            ".note",          /* ignore ELF notes - may contain anything */
            ".got",                 /* powerpc - global offset table */
            ".toc",                 /* powerpc - table of contents */
            NULL
      };
      /* part of section name */
      const char *namelist3 [] = {
            ".unwind",  /* Sample: IA_64.unwind.exit.text */
            NULL
      };

      for (s = namelist1; *s; s++)
            if (strcmp(*s, name) == 0)
                  return 1;
      for (s = namelist2; *s; s++)
            if (strncmp(*s, name, strlen(*s)) == 0)
                  return 1;
      for (s = namelist3; *s; s++)
            if (strstr(name, *s) != NULL)
                  return 1;
      return 0;
}


/*
 * Identify sections from which references to a .init section is OK.
 *
 * Unfortunately references to read only data that referenced .init
 * sections had to be excluded. Almost all of these are false
 * positives, they are created by gcc. The downside of excluding rodata
 * is that there really are some user references from rodata to
 * init code, e.g. drivers/video/vgacon.c:
 *
 * const struct consw vga_con = {
 *        con_startup:            vgacon_startup,
 *
 * where vgacon_startup is __init.  If you want to wade through the false
 * positives, take out the check for rodata.
 */
static int init_section_ref_ok(const char *name)
{
      const char **s;
      /* Absolute section names */
      const char *namelist1[] = {
            "__dbe_table",          /* MIPS generate these */
            "__ftr_fixup",          /* powerpc cpu feature fixup */
            "__fw_ftr_fixup", /* powerpc firmware feature fixup */
            "__param",
            ".data.rel.ro",         /* used by parisc64 */
            ".init",
            ".text.lock",
            NULL
      };
      /* Start of section names */
      const char *namelist2[] = {
            ".init.",
            ".pci_fixup",
            ".rodata",
            NULL
      };

      if (initexit_section_ref_ok(name))
            return 1;

      for (s = namelist1; *s; s++)
            if (strcmp(*s, name) == 0)
                  return 1;
      for (s = namelist2; *s; s++)
            if (strncmp(*s, name, strlen(*s)) == 0)
                  return 1;

      /* If section name ends with ".init" we allow references
       * as is the case with .initcallN.init, .early_param.init, .taglist.init etc
       */
      if (strrcmp(name, ".init") == 0)
            return 1;
      return 0;
}

/*
 * Identify sections from which references to a .exit section is OK.
 */
static int exit_section_ref_ok(const char *name)
{
      const char **s;
      /* Absolute section names */
      const char *namelist1[] = {
            ".exit.data",
            ".exit.text",
            ".exitcall.exit",
            ".rodata",
            NULL
      };

      if (initexit_section_ref_ok(name))
            return 1;

      for (s = namelist1; *s; s++)
            if (strcmp(*s, name) == 0)
                  return 1;
      return 0;
}

static void read_symbols(char *modname)
{
      const char *symname;
      char *version;
      char *license;
      struct module *mod;
      struct elf_info info = { };
      Elf_Sym *sym;

      if (!parse_elf(&info, modname))
            return;

      mod = new_module(modname);

      /* When there's no vmlinux, don't print warnings about
       * unresolved symbols (since there'll be too many ;) */
      if (is_vmlinux(modname)) {
            have_vmlinux = 1;
            mod->skip = 1;
      }

      license = get_modinfo(info.modinfo, info.modinfo_len, "license");
      while (license) {
            if (license_is_gpl_compatible(license))
                  mod->gpl_compatible = 1;
            else {
                  mod->gpl_compatible = 0;
                  break;
            }
            license = get_next_modinfo(info.modinfo, info.modinfo_len,
                                 "license", license);
      }

      for (sym = info.symtab_start; sym < info.symtab_stop; sym++) {
            symname = info.strtab + sym->st_name;

            handle_modversions(mod, &info, sym, symname);
            handle_moddevtable(mod, &info, sym, symname);
      }
      if (is_vmlinux(modname) && vmlinux_section_warnings) {
            check_sec_ref(mod, modname, &info, init_section, init_section_ref_ok);
            check_sec_ref(mod, modname, &info, exit_section, exit_section_ref_ok);
      }

      version = get_modinfo(info.modinfo, info.modinfo_len, "version");
      if (version)
            maybe_frob_rcs_version(modname, version, info.modinfo,
                               version - (char *)info.hdr);
      if (version || (all_versions && !is_vmlinux(modname)))
            get_src_version(modname, mod->srcversion,
                        sizeof(mod->srcversion)-1);

      parse_elf_finish(&info);

      /* Our trick to get versioning for struct_module - it's
       * never passed as an argument to an exported function, so
       * the automatic versioning doesn't pick it up, but it's really
       * important anyhow */
      if (modversions)
            mod->unres = alloc_symbol("struct_module", 0, mod->unres);
}

#define SZ 500

/* We first write the generated file into memory using the
 * following helper, then compare to the file on disk and
 * only update the later if anything changed */

void __attribute__((format(printf, 2, 3))) buf_printf(struct buffer *buf,
                                          const char *fmt, ...)
{
      char tmp[SZ];
      int len;
      va_list ap;

      va_start(ap, fmt);
      len = vsnprintf(tmp, SZ, fmt, ap);
      buf_write(buf, tmp, len);
      va_end(ap);
}

void buf_write(struct buffer *buf, const char *s, int len)
{
      if (buf->size - buf->pos < len) {
            buf->size += len + SZ;
            buf->p = realloc(buf->p, buf->size);
      }
      strncpy(buf->p + buf->pos, s, len);
      buf->pos += len;
}

static void check_for_gpl_usage(enum export exp, const char *m, const char *s)
{
      const char *e = is_vmlinux(m) ?"":".ko";

      switch (exp) {
      case export_gpl:
            fatal("modpost: GPL-incompatible module %s%s "
                  "uses GPL-only symbol '%s'\n", m, e, s);
            break;
      case export_unused_gpl:
            fatal("modpost: GPL-incompatible module %s%s "
                  "uses GPL-only symbol marked UNUSED '%s'\n", m, e, s);
            break;
      case export_gpl_future:
            warn("modpost: GPL-incompatible module %s%s "
                  "uses future GPL-only symbol '%s'\n", m, e, s);
            break;
      case export_plain:
      case export_unused:
      case export_unknown:
            /* ignore */
            break;
      }
}

static void check_for_unused(enum export exp, const char* m, const char* s)
{
      const char *e = is_vmlinux(m) ?"":".ko";

      switch (exp) {
      case export_unused:
      case export_unused_gpl:
            warn("modpost: module %s%s "
                  "uses symbol '%s' marked UNUSED\n", m, e, s);
            break;
      default:
            /* ignore */
            break;
      }
}

static void check_exports(struct module *mod)
{
      struct symbol *s, *exp;

      for (s = mod->unres; s; s = s->next) {
            const char *basename;
            exp = find_symbol(s->name);
            if (!exp || exp->module == mod)
                  continue;
            basename = strrchr(mod->name, '/');
            if (basename)
                  basename++;
            else
                  basename = mod->name;
            if (!mod->gpl_compatible)
                  check_for_gpl_usage(exp->export, basename, exp->name);
            check_for_unused(exp->export, basename, exp->name);
        }
}

/**
 * Header for the generated file
 **/
static void add_header(struct buffer *b, struct module *mod)
{
      buf_printf(b, "#include <linux/module.h>\n");
      buf_printf(b, "#include <linux/vermagic.h>\n");
      buf_printf(b, "#include <linux/compiler.h>\n");
      buf_printf(b, "\n");
      buf_printf(b, "MODULE_INFO(vermagic, VERMAGIC_STRING);\n");
      buf_printf(b, "\n");
      buf_printf(b, "struct module __this_module\n");
      buf_printf(b, "__attribute__((section(\".gnu.linkonce.this_module\"))) = {\n");
      buf_printf(b, " .name = KBUILD_MODNAME,\n");
      if (mod->has_init)
            buf_printf(b, " .init = init_module,\n");
      if (mod->has_cleanup)
            buf_printf(b, "#ifdef CONFIG_MODULE_UNLOAD\n"
                        " .exit = cleanup_module,\n"
                        "#endif\n");
      buf_printf(b, " .arch = MODULE_ARCH_INIT,\n");
      buf_printf(b, "};\n");
}

/**
 * Record CRCs for unresolved symbols
 **/
static int add_versions(struct buffer *b, struct module *mod)
{
      struct symbol *s, *exp;
      int err = 0;

      for (s = mod->unres; s; s = s->next) {
            exp = find_symbol(s->name);
            if (!exp || exp->module == mod) {
                  if (have_vmlinux && !s->weak) {
                        if (warn_unresolved) {
                              warn("\"%s\" [%s.ko] undefined!\n",
                                   s->name, mod->name);
                        } else {
                              merror("\"%s\" [%s.ko] undefined!\n",
                                        s->name, mod->name);
                              err = 1;
                        }
                  }
                  continue;
            }
            s->module = exp->module;
            s->crc_valid = exp->crc_valid;
            s->crc = exp->crc;
      }

      if (!modversions)
            return err;

      buf_printf(b, "\n");
      buf_printf(b, "static const struct modversion_info ____versions[]\n");
      buf_printf(b, "__attribute_used__\n");
      buf_printf(b, "__attribute__((section(\"__versions\"))) = {\n");

      for (s = mod->unres; s; s = s->next) {
            if (!s->module) {
                  continue;
            }
            if (!s->crc_valid) {
                  warn("\"%s\" [%s.ko] has no CRC!\n",
                        s->name, mod->name);
                  continue;
            }
            buf_printf(b, "\t{ %#8x, \"%s\" },\n", s->crc, s->name);
      }

      buf_printf(b, "};\n");

      return err;
}

static void add_depends(struct buffer *b, struct module *mod,
                  struct module *modules)
{
      struct symbol *s;
      struct module *m;
      int first = 1;

      for (m = modules; m; m = m->next) {
            m->seen = is_vmlinux(m->name);
      }

      buf_printf(b, "\n");
      buf_printf(b, "static const char __module_depends[]\n");
      buf_printf(b, "__attribute_used__\n");
      buf_printf(b, "__attribute__((section(\".modinfo\"))) =\n");
      buf_printf(b, "\"depends=");
      for (s = mod->unres; s; s = s->next) {
            const char *p;
            if (!s->module)
                  continue;

            if (s->module->seen)
                  continue;

            s->module->seen = 1;
            if ((p = strrchr(s->module->name, '/')) != NULL)
                  p++;
            else
                  p = s->module->name;
            buf_printf(b, "%s%s", first ? "" : ",", p);
            first = 0;
      }
      buf_printf(b, "\";\n");
}

static void add_srcversion(struct buffer *b, struct module *mod)
{
      if (mod->srcversion[0]) {
            buf_printf(b, "\n");
            buf_printf(b, "MODULE_INFO(srcversion, \"%s\");\n",
                     mod->srcversion);
      }
}

static void write_if_changed(struct buffer *b, const char *fname)
{
      char *tmp;
      FILE *file;
      struct stat st;

      file = fopen(fname, "r");
      if (!file)
            goto write;

      if (fstat(fileno(file), &st) < 0)
            goto close_write;

      if (st.st_size != b->pos)
            goto close_write;

      tmp = NOFAIL(malloc(b->pos));
      if (fread(tmp, 1, b->pos, file) != b->pos)
            goto free_write;

      if (memcmp(tmp, b->p, b->pos) != 0)
            goto free_write;

      free(tmp);
      fclose(file);
      return;

 free_write:
      free(tmp);
 close_write:
      fclose(file);
 write:
      file = fopen(fname, "w");
      if (!file) {
            perror(fname);
            exit(1);
      }
      if (fwrite(b->p, 1, b->pos, file) != b->pos) {
            perror(fname);
            exit(1);
      }
      fclose(file);
}

/* parse Module.symvers file. line format:
 * 0x12345678<tab>symbol<tab>module[[<tab>export]<tab>something]
 **/
static void read_dump(const char *fname, unsigned int kernel)
{
      unsigned long size, pos = 0;
      void *file = grab_file(fname, &size);
      char *line;

        if (!file)
            /* No symbol versions, silently ignore */
            return;

      while ((line = get_next_line(&pos, file, size))) {
            char *symname, *modname, *d, *export, *end;
            unsigned int crc;
            struct module *mod;
            struct symbol *s;

            if (!(symname = strchr(line, '\t')))
                  goto fail;
            *symname++ = '\0';
            if (!(modname = strchr(symname, '\t')))
                  goto fail;
            *modname++ = '\0';
            if ((export = strchr(modname, '\t')) != NULL)
                  *export++ = '\0';
            if (export && ((end = strchr(export, '\t')) != NULL))
                  *end = '\0';
            crc = strtoul(line, &d, 16);
            if (*symname == '\0' || *modname == '\0' || *d != '\0')
                  goto fail;

            if (!(mod = find_module(modname))) {
                  if (is_vmlinux(modname)) {
                        have_vmlinux = 1;
                  }
                  mod = new_module(NOFAIL(strdup(modname)));
                  mod->skip = 1;
            }
            s = sym_add_exported(symname, mod, export_no(export));
            s->kernel    = kernel;
            s->preloaded = 1;
            sym_update_crc(symname, mod, crc, export_no(export));
      }
      return;
fail:
      fatal("parse error in symbol dump file\n");
}

/* For normal builds always dump all symbols.
 * For external modules only dump symbols
 * that are not read from kernel Module.symvers.
 **/
static int dump_sym(struct symbol *sym)
{
      if (!external_module)
            return 1;
      if (sym->vmlinux || sym->kernel)
            return 0;
      return 1;
}

static void write_dump(const char *fname)
{
      struct buffer buf = { };
      struct symbol *symbol;
      int n;

      for (n = 0; n < SYMBOL_HASH_SIZE ; n++) {
            symbol = symbolhash[n];
            while (symbol) {
                  if (dump_sym(symbol))
                        buf_printf(&buf, "0x%08x\t%s\t%s\t%s\n",
                              symbol->crc, symbol->name,
                              symbol->module->name,
                              export_str(symbol->export));
                  symbol = symbol->next;
            }
      }
      write_if_changed(&buf, fname);
}

int main(int argc, char **argv)
{
      struct module *mod;
      struct buffer buf = { };
      char fname[SZ];
      char *kernel_read = NULL, *module_read = NULL;
      char *dump_write = NULL;
      int opt;
      int err;

      while ((opt = getopt(argc, argv, "i:I:mso:aw")) != -1) {
            switch(opt) {
                  case 'i':
                        kernel_read = optarg;
                        break;
                  case 'I':
                        module_read = optarg;
                        external_module = 1;
                        break;
                  case 'm':
                        modversions = 1;
                        break;
                  case 'o':
                        dump_write = optarg;
                        break;
                  case 'a':
                        all_versions = 1;
                        break;
                  case 's':
                        vmlinux_section_warnings = 0;
                        break;
                  case 'w':
                        warn_unresolved = 1;
                        break;
                  default:
                        exit(1);
            }
      }

      if (kernel_read)
            read_dump(kernel_read, 1);
      if (module_read)
            read_dump(module_read, 0);

      while (optind < argc) {
            read_symbols(argv[optind++]);
      }

      for (mod = modules; mod; mod = mod->next) {
            if (mod->skip)
                  continue;
            check_exports(mod);
      }

      err = 0;

      for (mod = modules; mod; mod = mod->next) {
            if (mod->skip)
                  continue;

            buf.pos = 0;

            add_header(&buf, mod);
            err |= add_versions(&buf, mod);
            add_depends(&buf, mod, modules);
            add_moddevtable(&buf, mod);
            add_srcversion(&buf, mod);

            sprintf(fname, "%s.mod.c", mod->name);
            write_if_changed(&buf, fname);
      }

      if (dump_write)
            write_dump(dump_write);

      return err;
}

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