modpost.c

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/* Postprocess module symbol versions
 *
 * Copyright 2003       Kai Germaschewski
 * Copyright 2002-2004  Rusty Russell, IBM Corporation
 * Copyright 2006-2008  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 ...
 */

#define _GNU_SOURCE
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include "modpost.h"
#include "../../include/generated/autoconf.h"
#include "../../include/linux/license.h"

/* Some toolchains use a `_' prefix for all user symbols. */
#ifdef CONFIG_SYMBOL_PREFIX
#define MODULE_SYMBOL_PREFIX CONFIG_SYMBOL_PREFIX
#else
#define MODULE_SYMBOL_PREFIX ""
#endif


/* 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 */
static int sec_mismatch_count = 0;
static int sec_mismatch_verbose = 1;

enum export {
    export_plain,      export_unused,     export_gpl,
    export_unused_gpl, export_gpl_future, export_unknown
};

#define PRINTF __attribute__ ((format (printf, 1, 2)))

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

    fprintf(stderr, "FATAL: ");

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

    exit(1);
}

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

    fprintf(stderr, "WARNING: ");

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

PRINTF 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;

    myname = strrchr(modname, '/');
    if (myname)
        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 */
    s = strrchr(p, '.');
    if (s != NULL)
        if (strcmp(s, ".o") == 0) {
            *s = '\0';
            mod->is_dot_o = 1;
        }

    /* 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);
}

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 const char *sec_name(struct elf_info *elf, int secindex);

#define strstarts(str, prefix) (strncmp(str, prefix, strlen(prefix)) == 0)

static enum export export_from_secname(struct elf_info *elf, unsigned int sec)
{
    const char *secname = sec_name(elf, sec);

    if (strstarts(secname, "___ksymtab+"))
        return export_plain;
    else if (strstarts(secname, "___ksymtab_unused+"))
        return export_unused;
    else if (strstarts(secname, "___ksymtab_gpl+"))
        return export_gpl;
    else if (strstarts(secname, "___ksymtab_unused_gpl+"))
        return export_unused_gpl;
    else if (strstarts(secname, "___ksymtab_gpl_future+"))
        return export_gpl_future;
    else
        return export_unknown;
}

static enum export export_from_sec(struct elf_info *elf, unsigned int 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;
}

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 = MAP_FAILED;
    int fd;

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

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

failed:
    close(fd);
    if (map == MAP_FAILED)
        return NULL;
    return map;
}

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;
    const char *secstrings;
    unsigned int symtab_idx = ~0U, symtab_shndx_idx = ~0U;

    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_type      = TO_NATIVE(hdr->e_type);
    hdr->e_machine   = TO_NATIVE(hdr->e_machine);
    hdr->e_version   = TO_NATIVE(hdr->e_version);
    hdr->e_entry     = TO_NATIVE(hdr->e_entry);
    hdr->e_phoff     = TO_NATIVE(hdr->e_phoff);
    hdr->e_shoff     = TO_NATIVE(hdr->e_shoff);
    hdr->e_flags     = TO_NATIVE(hdr->e_flags);
    hdr->e_ehsize    = TO_NATIVE(hdr->e_ehsize);
    hdr->e_phentsize = TO_NATIVE(hdr->e_phentsize);
    hdr->e_phnum     = TO_NATIVE(hdr->e_phnum);
    hdr->e_shentsize = TO_NATIVE(hdr->e_shentsize);
    hdr->e_shnum     = TO_NATIVE(hdr->e_shnum);
    hdr->e_shstrndx  = TO_NATIVE(hdr->e_shstrndx);
    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=%lu in file '%s' is bigger than "
              "filesize=%lu\n", (unsigned long)hdr->e_shoff,
              filename, info->size);
        return 0;
    }

    if (hdr->e_shnum == SHN_UNDEF) {
        /*
         * There are more than 64k sections,
         * read count from .sh_size.
         */
        info->num_sections = TO_NATIVE(sechdrs[0].sh_size);
    }
    else {
        info->num_sections = hdr->e_shnum;
    }
    if (hdr->e_shstrndx == SHN_XINDEX) {
        info->secindex_strings = TO_NATIVE(sechdrs[0].sh_link);
    }
    else {
        info->secindex_strings = hdr->e_shstrndx;
    }

    /* Fix endianness in section headers */
    for (i = 0; i < info->num_sections; i++) {
        sechdrs[i].sh_name      = TO_NATIVE(sechdrs[i].sh_name);
        sechdrs[i].sh_type      = TO_NATIVE(sechdrs[i].sh_type);
        sechdrs[i].sh_flags     = TO_NATIVE(sechdrs[i].sh_flags);
        sechdrs[i].sh_addr      = TO_NATIVE(sechdrs[i].sh_addr);
        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_info      = TO_NATIVE(sechdrs[i].sh_info);
        sechdrs[i].sh_addralign = TO_NATIVE(sechdrs[i].sh_addralign);
        sechdrs[i].sh_entsize   = TO_NATIVE(sechdrs[i].sh_entsize);
    }
    /* Find symbol table. */
    secstrings = (void *)hdr + sechdrs[info->secindex_strings].sh_offset;
    for (i = 1; i < info->num_sections; i++) {
        const char *secname;
        int nobits = sechdrs[i].sh_type == SHT_NOBITS;

        if (!nobits && sechdrs[i].sh_offset > info->size) {
            fatal("%s is truncated. sechdrs[i].sh_offset=%lu > "
                  "sizeof(*hrd)=%zu\n", filename,
                  (unsigned long)sechdrs[i].sh_offset,
                  sizeof(*hdr));
            return 0;
        }
        secname = secstrings + sechdrs[i].sh_name;
        if (strcmp(secname, ".modinfo") == 0) {
            if (nobits)
                fatal("%s has NOBITS .modinfo\n", filename);
            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) {
            unsigned int sh_link_idx;
            symtab_idx = i;
            info->symtab_start = (void *)hdr +
                sechdrs[i].sh_offset;
            info->symtab_stop  = (void *)hdr +
                sechdrs[i].sh_offset + sechdrs[i].sh_size;
            sh_link_idx = sechdrs[i].sh_link;
            info->strtab       = (void *)hdr +
                sechdrs[sh_link_idx].sh_offset;
        }

        /* 32bit section no. table? ("more than 64k sections") */
        if (sechdrs[i].sh_type == SHT_SYMTAB_SHNDX) {
            symtab_shndx_idx = i;
            info->symtab_shndx_start = (void *)hdr +
                sechdrs[i].sh_offset;
            info->symtab_shndx_stop  = (void *)hdr +
                sechdrs[i].sh_offset + sechdrs[i].sh_size;
        }
    }
    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);
    }

    if (symtab_shndx_idx != ~0U) {
        Elf32_Word *p;
        if (symtab_idx != sechdrs[symtab_shndx_idx].sh_link)
            fatal("%s: SYMTAB_SHNDX has bad sh_link: %u!=%u\n",
                  filename, sechdrs[symtab_shndx_idx].sh_link,
                  symtab_idx);
        /* Fix endianness */
        for (p = info->symtab_shndx_start; p < info->symtab_shndx_stop;
             p++)
            *p = TO_NATIVE(*p);
    }

    return 1;
}

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

static int ignore_undef_symbol(struct elf_info *info, const char *symname)
{
    /* ignore __this_module, it will be resolved shortly */
    if (strcmp(symname, MODULE_SYMBOL_PREFIX "__this_module") == 0)
        return 1;
    /* ignore global offset table */
    if (strcmp(symname, "_GLOBAL_OFFSET_TABLE_") == 0)
        return 1;
    if (info->hdr->e_machine == EM_PPC)
        /* Special register function linked on all modules during final link of .ko */
        if (strncmp(symname, "_restgpr_", sizeof("_restgpr_") - 1) == 0 ||
            strncmp(symname, "_savegpr_", sizeof("_savegpr_") - 1) == 0 ||
            strncmp(symname, "_rest32gpr_", sizeof("_rest32gpr_") - 1) == 0 ||
            strncmp(symname, "_save32gpr_", sizeof("_save32gpr_") - 1) == 0)
            return 1;
    if (info->hdr->e_machine == EM_PPC64)
        /* Special register function linked on all modules during final link of .ko */
        if (strncmp(symname, "_restgpr0_", sizeof("_restgpr0_") - 1) == 0 ||
            strncmp(symname, "_savegpr0_", sizeof("_savegpr0_") - 1) == 0)
            return 1;
    /* Do not ignore this symbol */
    return 0;
}

#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;

    if ((!is_vmlinux(mod->name) || mod->is_dot_o) &&
        strncmp(symname, "__ksymtab", 9) == 0)
        export = export_from_secname(info, get_secindex(info, sym));
    else
        export = export_from_sec(info, get_secindex(info, sym));

    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 (strncmp(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;
        if (ignore_undef_symbol(info, symname))
            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 (strncmp(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;
    }
}

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);
}

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);
}

static const char *sym_name(struct elf_info *elf, Elf_Sym *sym)
{
    if (sym)
        return elf->strtab + sym->st_name;
    else
        return "(unknown)";
}

static const char *sec_name(struct elf_info *elf, int secindex)
{
    Elf_Shdr *sechdrs = elf->sechdrs;
    return (void *)elf->hdr +
        elf->sechdrs[elf->secindex_strings].sh_offset +
        sechdrs[secindex].sh_name;
}

static const char *sech_name(struct elf_info *elf, Elf_Shdr *sechdr)
{
    return (void *)elf->hdr +
        elf->sechdrs[elf->secindex_strings].sh_offset +
        sechdr->sh_name;
}

/* if sym is empty or point to a string
 * like ".[0-9]+" then return 1.
 * This is the optional prefix added by ld to some sections
 */
static int number_prefix(const char *sym)
{
    if (*sym++ == '\0')
        return 1;
    if (*sym != '.')
        return 0;
    do {
        char c = *sym++;
        if (c < '0' || c > '9')
            return 0;
    } while (*sym);
    return 1;
}

/* The pattern is an array of simple patterns.
 * "foo" will match an exact string equal to "foo"
 * "*foo" will match a string that ends with "foo"
 * "foo*" will match a string that begins with "foo"
 * "foo$" will match a string equal to "foo" or "foo.1"
 *   where the '1' can be any number including several digits.
 *   The $ syntax is for sections where ld append a dot number
 *   to make section name unique.
 */
static int match(const char *sym, const char * const pat[])
{
    const char *p;
    while (*pat) {
        p = *pat++;
        const char *endp = p + strlen(p) - 1;

        /* "*foo" */
        if (*p == '*') {
            if (strrcmp(sym, p + 1) == 0)
                return 1;
        }
        /* "foo*" */
        else if (*endp == '*') {
            if (strncmp(sym, p, strlen(p) - 1) == 0)
                return 1;
        }
        /* "foo$" */
        else if (*endp == '$') {
            if (strncmp(sym, p, strlen(p) - 1) == 0) {
                if (number_prefix(sym + strlen(p) - 1))
                    return 1;
            }
        }
        /* no wildcards */
        else {
            if (strcmp(p, sym) == 0)
                return 1;
        }
    }
    /* no match */
    return 0;
}

/* sections that we do not want to do full section mismatch check on */
static const char *section_white_list[] =
{
    ".comment*",
    ".debug*",
    ".zdebug*",     /* Compressed debug sections. */
    ".GCC-command-line",    /* mn10300 */
    ".GCC.command.line",    /* record-gcc-switches, non mn10300 */
    ".mdebug*",        /* alpha, score, mips etc. */
    ".pdr",            /* alpha, score, mips etc. */
    ".stab*",
    ".note*",
    ".got*",
    ".toc*",
    ".xt.prop",              /* xtensa */
    ".xt.lit",         /* xtensa */
    NULL
};

/*
 * This is used to find sections missing the SHF_ALLOC flag.
 * The cause of this is often a section specified in assembler
 * without "ax" / "aw".
 */
static void check_section(const char *modname, struct elf_info *elf,
                          Elf_Shdr *sechdr)
{
    const char *sec = sech_name(elf, sechdr);

    if (sechdr->sh_type == SHT_PROGBITS &&
        !(sechdr->sh_flags & SHF_ALLOC) &&
        !match(sec, section_white_list)) {
        warn("%s (%s): unexpected non-allocatable section.\n"
             "Did you forget to use \"ax\"/\"aw\" in a .S file?\n"
             "Note that for example <linux/init.h> contains\n"
             "section definitions for use in .S files.\n\n",
             modname, sec);
    }
}



#define ALL_INIT_DATA_SECTIONS \
    ".init.setup$", ".init.rodata$", \
    ".devinit.rodata$", ".cpuinit.rodata$", ".meminit.rodata$", \
    ".init.data$", ".devinit.data$", ".cpuinit.data$", ".meminit.data$"
#define ALL_EXIT_DATA_SECTIONS \
    ".exit.data$", ".devexit.data$", ".cpuexit.data$", ".memexit.data$"

#define ALL_INIT_TEXT_SECTIONS \
    ".init.text$", ".devinit.text$", ".cpuinit.text$", ".meminit.text$"
#define ALL_EXIT_TEXT_SECTIONS \
    ".exit.text$", ".devexit.text$", ".cpuexit.text$", ".memexit.text$"

#define ALL_PCI_INIT_SECTIONS   \
    ".pci_fixup_early$", ".pci_fixup_header$", ".pci_fixup_final$", \
    ".pci_fixup_enable$", ".pci_fixup_resume$", \
    ".pci_fixup_resume_early$", ".pci_fixup_suspend$"

#define ALL_XXXINIT_SECTIONS DEV_INIT_SECTIONS, CPU_INIT_SECTIONS, \
    MEM_INIT_SECTIONS
#define ALL_XXXEXIT_SECTIONS DEV_EXIT_SECTIONS, CPU_EXIT_SECTIONS, \
    MEM_EXIT_SECTIONS

#define ALL_INIT_SECTIONS INIT_SECTIONS, ALL_XXXINIT_SECTIONS
#define ALL_EXIT_SECTIONS EXIT_SECTIONS, ALL_XXXEXIT_SECTIONS

#define DATA_SECTIONS ".data$", ".data.rel$"
#define TEXT_SECTIONS ".text$"

#define INIT_SECTIONS      ".init.*"
#define DEV_INIT_SECTIONS  ".devinit.*"
#define CPU_INIT_SECTIONS  ".cpuinit.*"
#define MEM_INIT_SECTIONS  ".meminit.*"

#define EXIT_SECTIONS      ".exit.*"
#define DEV_EXIT_SECTIONS  ".devexit.*"
#define CPU_EXIT_SECTIONS  ".cpuexit.*"
#define MEM_EXIT_SECTIONS  ".memexit.*"

/* init data sections */
static const char *init_data_sections[] = { ALL_INIT_DATA_SECTIONS, NULL };

/* all init sections */
static const char *init_sections[] = { ALL_INIT_SECTIONS, NULL };

/* All init and exit sections (code + data) */
static const char *init_exit_sections[] =
    {ALL_INIT_SECTIONS, ALL_EXIT_SECTIONS, NULL };

/* data section */
static const char *data_sections[] = { DATA_SECTIONS, NULL };


/* symbols in .data that may refer to init/exit sections */
#define DEFAULT_SYMBOL_WHITE_LIST                   \
    "*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"

static const char *head_sections[] = { ".head.text*", NULL };
static const char *linker_symbols[] =
    { "__init_begin", "_sinittext", "_einittext", NULL };

enum mismatch {
    TEXT_TO_ANY_INIT,
    DATA_TO_ANY_INIT,
    TEXT_TO_ANY_EXIT,
    DATA_TO_ANY_EXIT,
    XXXINIT_TO_SOME_INIT,
    XXXEXIT_TO_SOME_EXIT,
    ANY_INIT_TO_ANY_EXIT,
    ANY_EXIT_TO_ANY_INIT,
    EXPORT_TO_INIT_EXIT,
};

struct sectioncheck {
    const char *fromsec[20];
    const char *tosec[20];
    enum mismatch mismatch;
    const char *symbol_white_list[20];
};

const struct sectioncheck sectioncheck[] = {
/* Do not reference init/exit code/data from
 * normal code and data
 */
{
    .fromsec = { TEXT_SECTIONS, NULL },
    .tosec   = { ALL_INIT_SECTIONS, NULL },
    .mismatch = TEXT_TO_ANY_INIT,
    .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
{
    .fromsec = { DATA_SECTIONS, NULL },
    .tosec   = { ALL_XXXINIT_SECTIONS, NULL },
    .mismatch = DATA_TO_ANY_INIT,
    .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
{
    .fromsec = { DATA_SECTIONS, NULL },
    .tosec   = { INIT_SECTIONS, NULL },
    .mismatch = DATA_TO_ANY_INIT,
    .symbol_white_list = {
        "*_template", "*_timer", "*_sht", "*_ops",
        "*_probe", "*_probe_one", "*_console", NULL
    },
},
{
    .fromsec = { TEXT_SECTIONS, NULL },
    .tosec   = { ALL_EXIT_SECTIONS, NULL },
    .mismatch = TEXT_TO_ANY_EXIT,
    .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
{
    .fromsec = { DATA_SECTIONS, NULL },
    .tosec   = { ALL_EXIT_SECTIONS, NULL },
    .mismatch = DATA_TO_ANY_EXIT,
    .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
/* Do not reference init code/data from devinit/cpuinit/meminit code/data */
{
    .fromsec = { ALL_XXXINIT_SECTIONS, NULL },
    .tosec   = { INIT_SECTIONS, NULL },
    .mismatch = XXXINIT_TO_SOME_INIT,
    .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
/* Do not reference cpuinit code/data from meminit code/data */
{
    .fromsec = { MEM_INIT_SECTIONS, NULL },
    .tosec   = { CPU_INIT_SECTIONS, NULL },
    .mismatch = XXXINIT_TO_SOME_INIT,
    .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
/* Do not reference meminit code/data from cpuinit code/data */
{
    .fromsec = { CPU_INIT_SECTIONS, NULL },
    .tosec   = { MEM_INIT_SECTIONS, NULL },
    .mismatch = XXXINIT_TO_SOME_INIT,
    .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
/* Do not reference exit code/data from devexit/cpuexit/memexit code/data */
{
    .fromsec = { ALL_XXXEXIT_SECTIONS, NULL },
    .tosec   = { EXIT_SECTIONS, NULL },
    .mismatch = XXXEXIT_TO_SOME_EXIT,
    .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
/* Do not reference cpuexit code/data from memexit code/data */
{
    .fromsec = { MEM_EXIT_SECTIONS, NULL },
    .tosec   = { CPU_EXIT_SECTIONS, NULL },
    .mismatch = XXXEXIT_TO_SOME_EXIT,
    .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
/* Do not reference memexit code/data from cpuexit code/data */
{
    .fromsec = { CPU_EXIT_SECTIONS, NULL },
    .tosec   = { MEM_EXIT_SECTIONS, NULL },
    .mismatch = XXXEXIT_TO_SOME_EXIT,
    .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
/* Do not use exit code/data from init code */
{
    .fromsec = { ALL_INIT_SECTIONS, NULL },
    .tosec   = { ALL_EXIT_SECTIONS, NULL },
    .mismatch = ANY_INIT_TO_ANY_EXIT,
    .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
/* Do not use init code/data from exit code */
{
    .fromsec = { ALL_EXIT_SECTIONS, NULL },
    .tosec   = { ALL_INIT_SECTIONS, NULL },
    .mismatch = ANY_EXIT_TO_ANY_INIT,
    .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
{
    .fromsec = { ALL_PCI_INIT_SECTIONS, NULL },
    .tosec   = { INIT_SECTIONS, NULL },
    .mismatch = ANY_INIT_TO_ANY_EXIT,
    .symbol_white_list = { NULL },
},
/* Do not export init/exit functions or data */
{
    .fromsec = { "__ksymtab*", NULL },
    .tosec   = { INIT_SECTIONS, EXIT_SECTIONS, NULL },
    .mismatch = EXPORT_TO_INIT_EXIT,
    .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
}
};

static const struct sectioncheck *section_mismatch(
        const char *fromsec, const char *tosec)
{
    int i;
    int elems = sizeof(sectioncheck) / sizeof(struct sectioncheck);
    const struct sectioncheck *check = &sectioncheck[0];

    for (i = 0; i < elems; i++) {
        if (match(fromsec, check->fromsec) &&
            match(tosec, check->tosec))
            return check;
        check++;
    }
    return NULL;
}

static int secref_whitelist(const struct sectioncheck *mismatch,
                const char *fromsec, const char *fromsym,
                const char *tosec, const char *tosym)
{
    /* Check for pattern 1 */
    if (match(tosec, init_data_sections) &&
        match(fromsec, data_sections) &&
        (strncmp(fromsym, "__param", strlen("__param")) == 0))
        return 0;

    /* Check for pattern 1a */
    if (strcmp(tosec, ".init.text") == 0 &&
        match(fromsec, data_sections) &&
        (strncmp(fromsym, "__param_ops_", strlen("__param_ops_")) == 0))
        return 0;

    /* Check for pattern 2 */
    if (match(tosec, init_exit_sections) &&
        match(fromsec, data_sections) &&
        match(fromsym, mismatch->symbol_white_list))
        return 0;

    /* Check for pattern 3 */
    if (match(fromsec, head_sections) &&
        match(tosec, init_sections))
        return 0;

    /* Check for pattern 4 */
    if (match(tosym, linker_symbols))
        return 0;

    return 1;
}

static Elf_Sym *find_elf_symbol(struct elf_info *elf, Elf64_Sword addr,
                Elf_Sym *relsym)
{
    Elf_Sym *sym;
    Elf_Sym *near = NULL;
    Elf64_Sword distance = 20;
    Elf64_Sword d;
    unsigned int relsym_secindex;

    if (relsym->st_name != 0)
        return relsym;

    relsym_secindex = get_secindex(elf, relsym);
    for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) {
        if (get_secindex(elf, sym) != relsym_secindex)
            continue;
        if (ELF_ST_TYPE(sym->st_info) == STT_SECTION)
            continue;
        if (sym->st_value == addr)
            return sym;
        /* Find a symbol nearby - addr are maybe negative */
        d = sym->st_value - addr;
        if (d < 0)
            d = addr - sym->st_value;
        if (d < distance) {
            distance = d;
            near = sym;
        }
    }
    /* We need a close match */
    if (distance < 20)
        return near;
    else
        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 Elf_Sym *find_elf_symbol2(struct elf_info *elf, Elf_Addr addr,
                 const char *sec)
{
    Elf_Sym *sym;
    Elf_Sym *near = NULL;
    Elf_Addr distance = ~0;

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

        if (is_shndx_special(sym->st_shndx))
            continue;
        symsec = sec_name(elf, get_secindex(elf, sym));
        if (strcmp(symsec, sec) != 0)
            continue;
        if (!is_valid_name(elf, sym))
            continue;
        if (sym->st_value <= addr) {
            if ((addr - sym->st_value) < distance) {
                distance = addr - sym->st_value;
                near = sym;
            } else if ((addr - sym->st_value) == distance) {
                near = sym;
            }
        }
    }
    return near;
}

/*
 * Convert a section name to the function/data attribute
 * .init.text => __init
 * .cpuinit.data => __cpudata
 * .memexitconst => __memconst
 * etc.
 *
 * The memory of returned value has been allocated on a heap. The user of this
 * method should free it after usage.
*/
static char *sec2annotation(const char *s)
{
    if (match(s, init_exit_sections)) {
        char *p = malloc(20);
        char *r = p;

        *p++ = '_';
        *p++ = '_';
        if (*s == '.')
            s++;
        while (*s && *s != '.')
            *p++ = *s++;
        *p = '\0';
        if (*s == '.')
            s++;
        if (strstr(s, "rodata") != NULL)
            strcat(p, "const ");
        else if (strstr(s, "data") != NULL)
            strcat(p, "data ");
        else
            strcat(p, " ");
        return r;
    } else {
        return strdup("");
    }
}

static int is_function(Elf_Sym *sym)
{
    if (sym)
        return ELF_ST_TYPE(sym->st_info) == STT_FUNC;
    else
        return -1;
}

static void print_section_list(const char * const list[20])
{
    const char *const *s = list;

    while (*s) {
        fprintf(stderr, "%s", *s);
        s++;
        if (*s)
            fprintf(stderr, ", ");
    }
    fprintf(stderr, "\n");
}

/*
 * 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 report_sec_mismatch(const char *modname,
                const struct sectioncheck *mismatch,
                                const char *fromsec,
                                unsigned long long fromaddr,
                                const char *fromsym,
                                int from_is_func,
                                const char *tosec, const char *tosym,
                                int to_is_func)
{
    const char *from, *from_p;
    const char *to, *to_p;
    char *prl_from;
    char *prl_to;

    switch (from_is_func) {
    case 0: from = "variable"; from_p = "";   break;
    case 1: from = "function"; from_p = "()"; break;
    default: from = "(unknown reference)"; from_p = ""; break;
    }
    switch (to_is_func) {
    case 0: to = "variable"; to_p = "";   break;
    case 1: to = "function"; to_p = "()"; break;
    default: to = "(unknown reference)"; to_p = ""; break;
    }

    sec_mismatch_count++;
    if (!sec_mismatch_verbose)
        return;

    warn("%s(%s+0x%llx): Section mismatch in reference from the %s %s%s "
         "to the %s %s:%s%s\n",
         modname, fromsec, fromaddr, from, fromsym, from_p, to, tosec,
         tosym, to_p);

    switch (mismatch->mismatch) {
    case TEXT_TO_ANY_INIT:
        prl_from = sec2annotation(fromsec);
        prl_to = sec2annotation(tosec);
        fprintf(stderr,
        "The function %s%s() references\n"
        "the %s %s%s%s.\n"
        "This is often because %s lacks a %s\n"
        "annotation or the annotation of %s is wrong.\n",
        prl_from, fromsym,
        to, prl_to, tosym, to_p,
        fromsym, prl_to, tosym);
        free(prl_from);
        free(prl_to);
        break;
    case DATA_TO_ANY_INIT: {
        prl_to = sec2annotation(tosec);
        fprintf(stderr,
        "The variable %s references\n"
        "the %s %s%s%s\n"
        "If the reference is valid then annotate the\n"
        "variable with __init* or __refdata (see linux/init.h) "
        "or name the variable:\n",
        fromsym, to, prl_to, tosym, to_p);
        print_section_list(mismatch->symbol_white_list);
        free(prl_to);
        break;
    }
    case TEXT_TO_ANY_EXIT:
        prl_to = sec2annotation(tosec);
        fprintf(stderr,
        "The function %s() references a %s in an exit section.\n"
        "Often the %s %s%s has valid usage outside the exit section\n"
        "and the fix is to remove the %sannotation of %s.\n",
        fromsym, to, to, tosym, to_p, prl_to, tosym);
        free(prl_to);
        break;
    case DATA_TO_ANY_EXIT: {
        prl_to = sec2annotation(tosec);
        fprintf(stderr,
        "The variable %s references\n"
        "the %s %s%s%s\n"
        "If the reference is valid then annotate the\n"
        "variable with __exit* (see linux/init.h) or "
        "name the variable:\n",
        fromsym, to, prl_to, tosym, to_p);
        print_section_list(mismatch->symbol_white_list);
        free(prl_to);
        break;
    }
    case XXXINIT_TO_SOME_INIT:
    case XXXEXIT_TO_SOME_EXIT:
        prl_from = sec2annotation(fromsec);
        prl_to = sec2annotation(tosec);
        fprintf(stderr,
        "The %s %s%s%s references\n"
        "a %s %s%s%s.\n"
        "If %s is only used by %s then\n"
        "annotate %s with a matching annotation.\n",
        from, prl_from, fromsym, from_p,
        to, prl_to, tosym, to_p,
        tosym, fromsym, tosym);
        free(prl_from);
        free(prl_to);
        break;
    case ANY_INIT_TO_ANY_EXIT:
        prl_from = sec2annotation(fromsec);
        prl_to = sec2annotation(tosec);
        fprintf(stderr,
        "The %s %s%s%s references\n"
        "a %s %s%s%s.\n"
        "This is often seen when error handling "
        "in the init function\n"
        "uses functionality in the exit path.\n"
        "The fix is often to remove the %sannotation of\n"
        "%s%s so it may be used outside an exit section.\n",
        from, prl_from, fromsym, from_p,
        to, prl_to, tosym, to_p,
        prl_to, tosym, to_p);
        free(prl_from);
        free(prl_to);
        break;
    case ANY_EXIT_TO_ANY_INIT:
        prl_from = sec2annotation(fromsec);
        prl_to = sec2annotation(tosec);
        fprintf(stderr,
        "The %s %s%s%s references\n"
        "a %s %s%s%s.\n"
        "This is often seen when error handling "
        "in the exit function\n"
        "uses functionality in the init path.\n"
        "The fix is often to remove the %sannotation of\n"
        "%s%s so it may be used outside an init section.\n",
        from, prl_from, fromsym, from_p,
        to, prl_to, tosym, to_p,
        prl_to, tosym, to_p);
        free(prl_from);
        free(prl_to);
        break;
    case EXPORT_TO_INIT_EXIT:
        prl_to = sec2annotation(tosec);
        fprintf(stderr,
        "The symbol %s is exported and annotated %s\n"
        "Fix this by removing the %sannotation of %s "
        "or drop the export.\n",
        tosym, prl_to, prl_to, tosym);
        free(prl_to);
        break;
    }
    fprintf(stderr, "\n");
}

static void check_section_mismatch(const char *modname, struct elf_info *elf,
                                   Elf_Rela *r, Elf_Sym *sym, const char *fromsec)
{
    const char *tosec;
    const struct sectioncheck *mismatch;

    tosec = sec_name(elf, get_secindex(elf, sym));
    mismatch = section_mismatch(fromsec, tosec);
    if (mismatch) {
        Elf_Sym *to;
        Elf_Sym *from;
        const char *tosym;
        const char *fromsym;

        from = find_elf_symbol2(elf, r->r_offset, fromsec);
        fromsym = sym_name(elf, from);
        to = find_elf_symbol(elf, r->r_addend, sym);
        tosym = sym_name(elf, to);

        /* check whitelist - we may ignore it */
        if (secref_whitelist(mismatch,
                    fromsec, fromsym, tosec, tosym)) {
            report_sec_mismatch(modname, mismatch,
               fromsec, r->r_offset, fromsym,
               is_function(from), tosec, tosym,
               is_function(to));
        }
    }
}

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

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

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

#ifndef R_ARM_CALL
#define R_ARM_CALL  28
#endif
#ifndef R_ARM_JUMP24
#define R_ARM_JUMP24    29
#endif

static int addend_arm_rel(struct elf_info *elf, Elf_Shdr *sechdr, 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:
    case R_ARM_CALL:
    case R_ARM_JUMP24:
        /* From ARM ABI: ((S + A) | T) - P */
        r->r_addend = (int)(long)(elf->hdr +
                      sechdr->sh_offset +
                      (r->r_offset - sechdr->sh_addr));
        break;
    default:
        return 1;
    }
    return 0;
}

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

static void section_rela(const char *modname, struct elf_info *elf,
                         Elf_Shdr *sechdr)
{
    Elf_Sym  *sym;
    Elf_Rela *rela;
    Elf_Rela r;
    unsigned int r_sym;
    const char *fromsec;

    Elf_Rela *start = (void *)elf->hdr + sechdr->sh_offset;
    Elf_Rela *stop  = (void *)start + sechdr->sh_size;

    fromsec = sech_name(elf, sechdr);
    fromsec += strlen(".rela");
    /* if from section (name) is know good then skip it */
    if (match(fromsec, section_white_list))
        return;

    for (rela = start; rela < stop; rela++) {
        r.r_offset = TO_NATIVE(rela->r_offset);
#if KERNEL_ELFCLASS == ELFCLASS64
        if (elf->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 (is_shndx_special(sym->st_shndx))
            continue;
        check_section_mismatch(modname, elf, &r, sym, fromsec);
    }
}

static void section_rel(const char *modname, struct elf_info *elf,
                        Elf_Shdr *sechdr)
{
    Elf_Sym *sym;
    Elf_Rel *rel;
    Elf_Rela r;
    unsigned int r_sym;
    const char *fromsec;

    Elf_Rel *start = (void *)elf->hdr + sechdr->sh_offset;
    Elf_Rel *stop  = (void *)start + sechdr->sh_size;

    fromsec = sech_name(elf, sechdr);
    fromsec += strlen(".rel");
    /* if from section (name) is know good then skip it */
    if (match(fromsec, section_white_list))
        return;

    for (rel = start; rel < stop; rel++) {
        r.r_offset = TO_NATIVE(rel->r_offset);
#if KERNEL_ELFCLASS == ELFCLASS64
        if (elf->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 (elf->hdr->e_machine) {
        case EM_386:
            if (addend_386_rel(elf, sechdr, &r))
                continue;
            break;
        case EM_ARM:
            if (addend_arm_rel(elf, sechdr, &r))
                continue;
            break;
        case EM_MIPS:
            if (addend_mips_rel(elf, sechdr, &r))
                continue;
            break;
        }
        sym = elf->symtab_start + r_sym;
        /* Skip special sections */
        if (is_shndx_special(sym->st_shndx))
            continue;
        check_section_mismatch(modname, elf, &r, sym, fromsec);
    }
}

static void check_sec_ref(struct module *mod, const char *modname,
                          struct elf_info *elf)
{
    int i;
    Elf_Shdr *sechdrs = elf->sechdrs;

    /* Walk through all sections */
    for (i = 0; i < elf->num_sections; i++) {
        check_section(modname, elf, &elf->sechdrs[i]);
        /* We want to process only relocation sections and not .init */
        if (sechdrs[i].sh_type == SHT_RELA)
            section_rela(modname, elf, &elf->sechdrs[i]);
        else if (sechdrs[i].sh_type == SHT_REL)
            section_rel(modname, elf, &elf->sechdrs[i]);
    }
}

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");
    if (info.modinfo && !license && !is_vmlinux(modname))
        warn("modpost: missing MODULE_LICENSE() in %s\n"
             "see include/linux/module.h for "
             "more information\n", modname);
    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) ||
         (is_vmlinux(modname) && vmlinux_section_warnings))
        check_sec_ref(mod, modname, &info);

    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 module struct etc. - 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("module_layout", 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);
    }
}

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, "\t.name = KBUILD_MODNAME,\n");
    if (mod->has_init)
        buf_printf(b, "\t.init = init_module,\n");
    if (mod->has_cleanup)
        buf_printf(b, "#ifdef CONFIG_MODULE_UNLOAD\n"
                  "\t.exit = cleanup_module,\n"
                  "#endif\n");
    buf_printf(b, "\t.arch = MODULE_ARCH_INIT,\n");
    buf_printf(b, "};\n");
}

static void add_intree_flag(struct buffer *b, int is_intree)
{
    if (is_intree)
        buf_printf(b, "\nMODULE_INFO(intree, \"Y\");\n");
}

static void add_staging_flag(struct buffer *b, const char *name)
{
    static const char *staging_dir = "drivers/staging";

    if (strncmp(staging_dir, name, strlen(staging_dir)) == 0)
        buf_printf(b, "\nMODULE_INFO(staging, \"Y\");\n");
}

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, "__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, "__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;
        p = strrchr(s->module->name, '/');
        if (p)
            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;
        mod = find_module(modname);
        if (!mod) {
            if (is_vmlinux(modname))
                have_vmlinux = 1;
            mod = new_module(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);
}

struct ext_sym_list {
    struct ext_sym_list *next;
    const char *file;
};

int main(int argc, char **argv)
{
    struct module *mod;
    struct buffer buf = { };
    char *kernel_read = NULL, *module_read = NULL;
    char *dump_write = NULL;
    int opt;
    int err;
    struct ext_sym_list *extsym_iter;
    struct ext_sym_list *extsym_start = NULL;

    while ((opt = getopt(argc, argv, "i:I:e:cmsSo:awM:K:")) != -1) {
        switch (opt) {
        case 'i':
            kernel_read = optarg;
            break;
        case 'I':
            module_read = optarg;
            external_module = 1;
            break;
        case 'c':
            cross_build = 1;
            break;
        case 'e':
            external_module = 1;
            extsym_iter =
               NOFAIL(malloc(sizeof(*extsym_iter)));
            extsym_iter->next = extsym_start;
            extsym_iter->file = optarg;
            extsym_start = extsym_iter;
            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 'S':
            sec_mismatch_verbose = 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 (extsym_start) {
        read_dump(extsym_start->file, 0);
        extsym_iter = extsym_start->next;
        free(extsym_start);
        extsym_start = extsym_iter;
    }

    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) {
        char fname[strlen(mod->name) + 10];

        if (mod->skip)
            continue;

        buf.pos = 0;

        add_header(&buf, mod);
        add_intree_flag(&buf, !external_module);
        add_staging_flag(&buf, mod->name);
        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);
    if (sec_mismatch_count && !sec_mismatch_verbose)
        warn("modpost: Found %d section mismatch(es).\n"
             "To see full details build your kernel with:\n"
             "'make CONFIG_DEBUG_SECTION_MISMATCH=y'\n",
             sec_mismatch_count);

    return err;
}