/* 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);
}

/**
 * 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 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;
}

/**
 * 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 = 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;
}

/**
  * 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;
        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;
        }
}

/**
 * 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);
}

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;
}

/**
 * Whitelist to allow certain references to pass with no warning.
 *
 * 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 1a:
 *   module_param_call() ops can refer to __init set function if permissions=0
 *   The pattern is identified by:
 *   tosec   = .init.text
 *   fromsec = .data*
 *   atsym   = __param_ops_*
 *
 * Pattern 2:
 *   Many drivers utilise a *driver container with references to
 *   add, remove, probe functions etc.
 *   These functions may often be marked __devinit 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 references from .head.text to any init section
 *
 * 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
 *
 **/
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;
}

/**
 * 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, 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);
        }
}

/**
 * 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 initialized.
 * Likewise for modules used built-in the sections marked __exit
 * are discarded because __exit marked function are supposed to be called
 * only when a module is unloaded which never happens 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 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);
        }
}

/**
 * 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, "\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");
}

/**
 * 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, "__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;
}