modpost.c 29.6 KB
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/* Postprocess module symbol versions
 *
 * Copyright 2003       Kai Germaschewski
 * Copyright 2002-2004  Rusty Russell, IBM Corporation
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 * Copyright 2006       Sam Ravnborg
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 * Based in part on module-init-tools/depmod.c,file2alias
 *
 * This software may be used and distributed according to the terms
 * of the GNU General Public License, incorporated herein by reference.
 *
 * Usage: modpost vmlinux module1.o module2.o ...
 */

#include <ctype.h>
#include "modpost.h"

/* 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;
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/* If we are modposting external module set to 1 */
static int external_module = 0;
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void fatal(const char *fmt, ...)
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{
	va_list arglist;

	fprintf(stderr, "FATAL: ");

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

	exit(1);
}

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

	fprintf(stderr, "WARNING: ");

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

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

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

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

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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;

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

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

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static struct module *new_module(char *modname)
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{
	struct module *mod;
	char *p, *s;
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	mod = NOFAIL(malloc(sizeof(*mod)));
	memset(mod, 0, sizeof(*mod));
	p = NOFAIL(strdup(modname));

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

	/* add to list */
	mod->name = p;
	mod->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;
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	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) **/
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	unsigned int preloaded:1;  /* 1 if symbol from Module.symvers */
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	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);
}

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/**
 * 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)
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{
	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 */
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static struct symbol *new_symbol(const char *name, struct module *module)
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{
	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;
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	return new;
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}

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

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

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

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

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

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

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

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

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

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/**
  * 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)
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{
	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;
}

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

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

	hdr = grab_file(filename, &info->size);
	if (!hdr) {
		perror(filename);
		abort();
	}
	info->hdr = hdr;
	if (info->size < sizeof(*hdr))
		goto truncated;

	/* Fix endianness in ELF header */
	hdr->e_shoff    = TO_NATIVE(hdr->e_shoff);
	hdr->e_shstrndx = TO_NATIVE(hdr->e_shstrndx);
	hdr->e_shnum    = TO_NATIVE(hdr->e_shnum);
	hdr->e_machine  = TO_NATIVE(hdr->e_machine);
	sechdrs = (void *)hdr + hdr->e_shoff;
	info->sechdrs = sechdrs;

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

		if (sechdrs[i].sh_offset > info->size)
			goto truncated;
		if (strcmp(secstrings+sechdrs[i].sh_name, ".modinfo") == 0) {
			info->modinfo = (void *)hdr + sechdrs[i].sh_offset;
			info->modinfo_len = sechdrs[i].sh_size;
		}
		if (sechdrs[i].sh_type != SHT_SYMTAB)
			continue;

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

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	fatal("%s is truncated.\n", filename);
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}

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

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#define CRC_PFX     "__crc_"
#define KSYMTAB_PFX "__ksymtab_"
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static void handle_modversions(struct module *mod, struct elf_info *info,
			       Elf_Sym *sym, const char *symname)
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{
	unsigned int crc;

	switch (sym->st_shndx) {
	case SHN_COMMON:
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		warn("\"%s\" [%s] is COMMON symbol\n", symname, mod->name);
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		break;
	case SHN_ABS:
		/* CRC'd symbol */
		if (memcmp(symname, CRC_PFX, strlen(CRC_PFX)) == 0) {
			crc = (unsigned int) sym->st_value;
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			sym_update_crc(symname + strlen(CRC_PFX), mod, crc);
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		}
		break;
	case SHN_UNDEF:
		/* undefined symbol */
		if (ELF_ST_BIND(sym->st_info) != STB_GLOBAL &&
		    ELF_ST_BIND(sym->st_info) != STB_WEAK)
			break;
		/* ignore global offset table */
		if (strcmp(symname, "_GLOBAL_OFFSET_TABLE_") == 0)
			break;
		/* ignore __this_module, it will be resolved shortly */
		if (strcmp(symname, MODULE_SYMBOL_PREFIX "__this_module") == 0)
			break;
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/* 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
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		if (info->hdr->e_machine == EM_SPARC ||
		    info->hdr->e_machine == EM_SPARCV9) {
			/* Ignore register directives. */
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			if (ELF_ST_TYPE(sym->st_info) == STT_SPARC_REGISTER)
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				break;
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			if (symname[0] == '.') {
				char *munged = strdup(symname);
				munged[0] = '_';
				munged[1] = toupper(munged[1]);
				symname = munged;
			}
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		}
#endif
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		if (memcmp(symname, MODULE_SYMBOL_PREFIX,
			   strlen(MODULE_SYMBOL_PREFIX)) == 0)
			mod->unres = alloc_symbol(symname +
						  strlen(MODULE_SYMBOL_PREFIX),
						  ELF_ST_BIND(sym->st_info) == STB_WEAK,
						  mod->unres);
		break;
	default:
		/* All exported symbols */
		if (memcmp(symname, KSYMTAB_PFX, strlen(KSYMTAB_PFX)) == 0) {
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			sym_add_exported(symname + strlen(KSYMTAB_PFX), mod);
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		}
		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;
	}
}

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/**
 * Parse tag=value strings from .modinfo section
 **/
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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_modinfo(void *modinfo, unsigned long modinfo_len,
			 const char *tag)
{
	char *p;
	unsigned int taglen = strlen(tag);
	unsigned long size = modinfo_len;

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

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/**
 * Test if string s ends in string sub
 * return 0 if match
 **/
static int strrcmp(const char *s, const char *sub)
{
        int slen, sublen;
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	if (!s || !sub)
		return 1;
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	slen = strlen(s);
        sublen = strlen(sub);
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	if ((slen == 0) || (sublen == 0))
		return 1;

        if (sublen > slen)
                return 1;

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

/**
 * 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
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 *   fromsec = .data*
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 *   atsym   =__param*
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 *
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 * Pattern 2:
 *   Many drivers utilise a *_driver container with references to
 *   add, remove, probe functions etc.
 *   These functions may often be marked __init and we do not want to
 *   warn here.
 *   the pattern is identified by:
 *   tosec   = .init.text | .exit.text
 *   fromsec = .data
 *   atsym = *_driver, *_ops, *_probe, *probe_one
 **/
static int secref_whitelist(const char *tosec, const char *fromsec,
			  const char *atsym)
{
	int f1 = 1, f2 = 1;
	const char **s;
	const char *pat2sym[] = {
		"_driver",
		"_ops",
		"_probe",
		"_probe_one",
		NULL
	};
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	/* Check for pattern 1 */
	if (strcmp(tosec, ".init.data") != 0)
		f1 = 0;
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	if (strncmp(fromsec, ".data", strlen(".data")) != 0)
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		f1 = 0;
	if (strncmp(atsym, "__param", strlen("__param")) != 0)
		f1 = 0;

	if (f1)
		return f1;

	/* Check for pattern 2 */
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	if ((strcmp(tosec, ".init.text") != 0) &&
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	    (strcmp(tosec, ".exit.text") != 0))
		f2 = 0;
	if (strcmp(fromsec, ".data") != 0)
		f2 = 0;

	for (s = pat2sym; *s; s++)
		if (strrcmp(atsym, *s) == 0)
			f1 = 1;

	return f1 && f2;
}

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

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

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/*
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 * 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.
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 **/
static void find_symbols_between(struct elf_info *elf, Elf_Addr addr,
				 const char *sec,
			         Elf_Sym **before, Elf_Sym **after)
{
	Elf_Sym *sym;
	Elf_Ehdr *hdr = elf->hdr;
	Elf_Addr beforediff = ~0;
	Elf_Addr afterdiff = ~0;
	const char *secstrings = (void *)hdr +
				 elf->sechdrs[hdr->e_shstrndx].sh_offset;
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	*before = NULL;
	*after = NULL;

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

		if (sym->st_shndx >= SHN_LORESERVE)
			continue;
		symsec = secstrings + elf->sechdrs[sym->st_shndx].sh_name;
		if (strcmp(symsec, sec) != 0)
			continue;
		if (sym->st_value <= addr) {
			if ((addr - sym->st_value) < beforediff) {
				beforediff = addr - sym->st_value;
				*before = sym;
			}
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			else if ((addr - sym->st_value) == beforediff) {
				/* equal offset, valid name? */
				const char *name = elf->strtab + sym->st_name;
				if (name && strlen(name))
					*before = sym;
			}
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		}
		else
		{
			if ((sym->st_value - addr) < afterdiff) {
				afterdiff = sym->st_value - addr;
				*after = sym;
			}
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			else if ((sym->st_value - addr) == afterdiff) {
				/* equal offset, valid name? */
				const char *name = elf->strtab + sym->st_name;
				if (name && strlen(name))
					*after = sym;
			}
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		}
	}
}

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

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	refsym = find_elf_symbol(elf, r.r_addend, sym);
	if (refsym && strlen(elf->strtab + refsym->st_name))
		refsymname = elf->strtab + refsym->st_name;
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	/* check whitelist - we may ignore it */
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	if (before &&
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	    secref_whitelist(secname, fromsec, elf->strtab + before->st_name))
		return;
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	if (before && after) {
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		warn("%s - Section mismatch: reference to %s:%s from %s "
		     "between '%s' (at offset 0x%llx) and '%s'\n",
		     modname, secname, refsymname, fromsec,
648
		     elf->strtab + before->st_name,
649
		     (long long)r.r_offset,
650 651
		     elf->strtab + after->st_name);
	} else if (before) {
652 653
		warn("%s - Section mismatch: reference to %s:%s from %s "
		     "after '%s' (at offset 0x%llx)\n",
654
		     modname, secname, refsymname, fromsec,
655
		     elf->strtab + before->st_name,
656
		     (long long)r.r_offset);
657
	} else if (after) {
658 659
		warn("%s - Section mismatch: reference to %s:%s from %s "
		     "before '%s' (at offset -0x%llx)\n",
660
		     modname, secname, refsymname, fromsec,
661
		     elf->strtab + before->st_name,
662
		     (long long)r.r_offset);
663
	} else {
664 665 666 667
		warn("%s - Section mismatch: reference to %s:%s from %s "
		     "(offset 0x%llx)\n",
		     modname, secname, fromsec, refsymname,
		     (long long)r.r_offset);
668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693
	}
}

/**
 * A module includes a number of sections that are discarded
 * either when loaded or when used as built-in.
 * For loaded modules all functions marked __init and all data
 * marked __initdata will be discarded when the module has been intialized.
 * Likewise for modules used built-in the sections marked __exit
 * are discarded because __exit marked function are supposed to be called
 * only when a moduel is unloaded which never happes for built-in modules.
 * The check_sec_ref() function traverses all relocation records
 * to find all references to a section that reference a section that will
 * be discarded and warns about it.
 **/
static void check_sec_ref(struct module *mod, const char *modname,
			  struct elf_info *elf,
			  int section(const char*),
			  int section_ref_ok(const char *))
{
	int i;
	Elf_Sym  *sym;
	Elf_Ehdr *hdr = elf->hdr;
	Elf_Shdr *sechdrs = elf->sechdrs;
	const char *secstrings = (void *)hdr +
				 sechdrs[hdr->e_shstrndx].sh_offset;
694

695 696
	/* Walk through all sections */
	for (i = 0; i < hdr->e_shnum; i++) {
697 698 699
		Elf_Rela *rela;
		Elf_Rela *start = (void *)hdr + sechdrs[i].sh_offset;
		Elf_Rela *stop  = (void*)start + sechdrs[i].sh_size;
700 701 702 703 704 705 706 707 708 709 710
		const char *name = secstrings + sechdrs[i].sh_name +
						strlen(".rela");
		/* We want to process only relocation sections and not .init */
		if (section_ref_ok(name) || (sechdrs[i].sh_type != SHT_RELA))
			continue;

		for (rela = start; rela < stop; rela++) {
			Elf_Rela r;
			const char *secname;
			r.r_offset = TO_NATIVE(rela->r_offset);
			r.r_info   = TO_NATIVE(rela->r_info);
711
			r.r_addend = TO_NATIVE(rela->r_addend);
712 713 714 715 716
			sym = elf->symtab_start + ELF_R_SYM(r.r_info);
			/* Skip special sections */
			if (sym->st_shndx >= SHN_LORESERVE)
				continue;

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			secname = secstrings + sechdrs[sym->st_shndx].sh_name;
718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741
			if (section(secname))
				warn_sec_mismatch(modname, name, elf, sym, r);
		}
	}
}

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

/**
 * Identify sections from which references to a .init section is OK.
742
 *
743 744 745 746 747
 * Unfortunately references to read only data that referenced .init
 * sections had to be excluded. Almost all of these are false
 * positives, they are created by gcc. The downside of excluding rodata
 * is that there really are some user references from rodata to
 * init code, e.g. drivers/video/vgacon.c:
748
 *
749 750 751 752 753 754 755 756 757 758 759 760
 * const struct consw vga_con = {
 *        con_startup:            vgacon_startup,
 *
 * where vgacon_startup is __init.  If you want to wade through the false
 * positives, take out the check for rodata.
 **/
static int init_section_ref_ok(const char *name)
{
	const char **s;
	/* Absolute section names */
	const char *namelist1[] = {
		".init",
761 762
		".opd",   /* see comment [OPD] at exit_section_ref_ok() */
		".toc1",  /* used by ppc64 */
763 764 765
		".stab",
		".rodata",
		".text.lock",
766
		"__bug_table", /* used by powerpc for BUG() */
767 768 769 770 771 772 773 774 775 776 777 778 779 780
		".pci_fixup_header",
		".pci_fixup_final",
		".pdr",
		"__param",
		NULL
	};
	/* Start of section names */
	const char *namelist2[] = {
		".init.",
		".altinstructions",
		".eh_frame",
		".debug",
		NULL
	};
781 782 783 784 785 786
	/* part of section name */
	const char *namelist3 [] = {
		".unwind",  /* sample: IA_64.unwind.init.text */
		NULL
	};

787 788 789
	for (s = namelist1; *s; s++)
		if (strcmp(*s, name) == 0)
			return 1;
790
	for (s = namelist2; *s; s++)
791 792
		if (strncmp(*s, name, strlen(*s)) == 0)
			return 1;
793
	for (s = namelist3; *s; s++)
794
		if (strstr(name, *s) != NULL)
795
			return 1;
796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812
	return 0;
}

/*
 * Functions used only during module exit is marked __exit and is stored in
 * a .exit.text section. Likewise data is marked __exitdata and stored in
 * a .exit.data section.
 * If this section is one of these sections return 1
 * See include/linux/init.h for the details
 **/
static int exit_section(const char *name)
{
	if (strcmp(name, ".exit.text") == 0)
		return 1;
	if (strcmp(name, ".exit.data") == 0)
		return 1;
	return 0;
813

814 815 816 817
}

/*
 * Identify sections from which references to a .exit section is OK.
818
 *
819 820 821 822 823 824 825 826 827 828 829 830 831 832
 * [OPD] Keith Ownes <kaos@sgi.com> commented:
 * For our future {in}sanity, add a comment that this is the ppc .opd
 * section, not the ia64 .opd section.
 * ia64 .opd should not point to discarded sections.
 **/
static int exit_section_ref_ok(const char *name)
{
	const char **s;
	/* Absolute section names */
	const char *namelist1[] = {
		".exit.text",
		".exit.data",
		".init.text",
		".opd", /* See comment [OPD] */
833
		".toc1",  /* used by ppc64 */
834 835
		".altinstructions",
		".pdr",
836
		"__bug_table", /* used by powerpc for BUG() */
837 838 839 840 841 842 843 844 845 846
		".exitcall.exit",
		".eh_frame",
		".stab",
		NULL
	};
	/* Start of section names */
	const char *namelist2[] = {
		".debug",
		NULL
	};
847 848 849 850 851
	/* part of section name */
	const char *namelist3 [] = {
		".unwind",  /* Sample: IA_64.unwind.exit.text */
		NULL
	};
852

853 854 855
	for (s = namelist1; *s; s++)
		if (strcmp(*s, name) == 0)
			return 1;
856
	for (s = namelist2; *s; s++)
857 858
		if (strncmp(*s, name, strlen(*s)) == 0)
			return 1;
859
	for (s = namelist3; *s; s++)
860
		if (strstr(name, *s) != NULL)
861
			return 1;
862 863 864
	return 0;
}

865
static void read_symbols(char *modname)
L
Linus Torvalds 已提交
866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889
{
	const char *symname;
	char *version;
	struct module *mod;
	struct elf_info info = { };
	Elf_Sym *sym;

	parse_elf(&info, modname);

	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;
	}

	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);
	}
890 891
	check_sec_ref(mod, modname, &info, init_section, init_section_ref_ok);
	check_sec_ref(mod, modname, &info, exit_section, exit_section_ref_ok);
L
Linus Torvalds 已提交
892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916

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

	parse_elf_finish(&info);

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

#define SZ 500

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

917 918
void __attribute__((format(printf, 2, 3))) buf_printf(struct buffer *buf,
						      const char *fmt, ...)
L
Linus Torvalds 已提交
919 920 921 922
{
	char tmp[SZ];
	int len;
	va_list ap;
923

L
Linus Torvalds 已提交
924 925 926 927 928 929 930 931 932 933 934
	va_start(ap, fmt);
	len = vsnprintf(tmp, SZ, fmt, ap);
	if (buf->size - buf->pos < len + 1) {
		buf->size += 128;
		buf->p = realloc(buf->p, buf->size);
	}
	strncpy(buf->p + buf->pos, tmp, len + 1);
	buf->pos += len;
	va_end(ap);
}

935
void buf_write(struct buffer *buf, const char *s, int len)
L
Linus Torvalds 已提交
936 937 938 939 940 941 942 943 944
{
	if (buf->size - buf->pos < len) {
		buf->size += len;
		buf->p = realloc(buf->p, buf->size);
	}
	strncpy(buf->p + buf->pos, s, len);
	buf->pos += len;
}

945 946 947 948
/**
 * Header for the generated file
 **/
static void add_header(struct buffer *b, struct module *mod)
L
Linus Torvalds 已提交
949 950 951 952 953 954 955 956 957
{
	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");
958
	buf_printf(b, " .name = KBUILD_MODNAME,\n");
L
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959 960 961 962 963 964 965 966 967
	if (mod->has_init)
		buf_printf(b, " .init = init_module,\n");
	if (mod->has_cleanup)
		buf_printf(b, "#ifdef CONFIG_MODULE_UNLOAD\n"
			      " .exit = cleanup_module,\n"
			      "#endif\n");
	buf_printf(b, "};\n");
}

968 969 970 971
/**
 * Record CRCs for unresolved symbols
 **/
static void add_versions(struct buffer *b, struct module *mod)
L
Linus Torvalds 已提交
972 973 974 975 976 977 978
{
	struct symbol *s, *exp;

	for (s = mod->unres; s; s = s->next) {
		exp = find_symbol(s->name);
		if (!exp || exp->module == mod) {
			if (have_vmlinux && !s->weak)
979 980
				warn("\"%s\" [%s.ko] undefined!\n",
				     s->name, mod->name);
L
Linus Torvalds 已提交
981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000
			continue;
		}
		s->module = exp->module;
		s->crc_valid = exp->crc_valid;
		s->crc = exp->crc;
	}

	if (!modversions)
		return;

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

	for (s = mod->unres; s; s = s->next) {
		if (!s->module) {
			continue;
		}
		if (!s->crc_valid) {
1001
			warn("\"%s\" [%s.ko] has no CRC!\n",
L
Linus Torvalds 已提交
1002 1003 1004 1005 1006 1007 1008 1009 1010
				s->name, mod->name);
			continue;
		}
		buf_printf(b, "\t{ %#8x, \"%s\" },\n", s->crc, s->name);
	}

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

1011 1012
static void add_depends(struct buffer *b, struct module *mod,
			struct module *modules)
L
Linus Torvalds 已提交
1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041
{
	struct symbol *s;
	struct module *m;
	int first = 1;

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

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

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

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

1042
static void add_srcversion(struct buffer *b, struct module *mod)
L
Linus Torvalds 已提交
1043 1044 1045 1046 1047 1048 1049 1050
{
	if (mod->srcversion[0]) {
		buf_printf(b, "\n");
		buf_printf(b, "MODULE_INFO(srcversion, \"%s\");\n",
			   mod->srcversion);
	}
}

1051
static void write_if_changed(struct buffer *b, const char *fname)
L
Linus Torvalds 已提交
1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094
{
	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);
}

1095
static void read_dump(const char *fname, unsigned int kernel)
L
Linus Torvalds 已提交
1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108
{
	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;
		unsigned int crc;
		struct module *mod;
1109
		struct symbol *s;
L
Linus Torvalds 已提交
1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129

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

		if (!(mod = find_module(modname))) {
			if (is_vmlinux(modname)) {
				have_vmlinux = 1;
			}
			mod = new_module(NOFAIL(strdup(modname)));
			mod->skip = 1;
		}
1130
		s = sym_add_exported(symname, mod);
1131 1132
		s->kernel    = kernel;
		s->preloaded = 1;
1133
		sym_update_crc(symname, mod, crc);
L
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1134 1135 1136 1137 1138 1139
	}
	return;
fail:
	fatal("parse error in symbol dump file\n");
}

1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151
/* 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;
}
1152

1153
static void write_dump(const char *fname)
L
Linus Torvalds 已提交
1154 1155 1156 1157 1158 1159 1160 1161
{
	struct buffer buf = { };
	struct symbol *symbol;
	int n;

	for (n = 0; n < SYMBOL_HASH_SIZE ; n++) {
		symbol = symbolhash[n];
		while (symbol) {
1162 1163
			if (dump_sym(symbol))
				buf_printf(&buf, "0x%08x\t%s\t%s\n",
1164
					symbol->crc, symbol->name,
1165
					symbol->module->name);
L
Linus Torvalds 已提交
1166 1167 1168 1169 1170 1171
			symbol = symbol->next;
		}
	}
	write_if_changed(&buf, fname);
}

1172
int main(int argc, char **argv)
L
Linus Torvalds 已提交
1173 1174 1175 1176
{
	struct module *mod;
	struct buffer buf = { };
	char fname[SZ];
1177 1178
	char *kernel_read = NULL, *module_read = NULL;
	char *dump_write = NULL;
L
Linus Torvalds 已提交
1179 1180
	int opt;

1181
	while ((opt = getopt(argc, argv, "i:I:mo:a")) != -1) {
L
Linus Torvalds 已提交
1182 1183
		switch(opt) {
			case 'i':
1184 1185 1186 1187 1188
				kernel_read = optarg;
				break;
			case 'I':
				module_read = optarg;
				external_module = 1;
L
Linus Torvalds 已提交
1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203
				break;
			case 'm':
				modversions = 1;
				break;
			case 'o':
				dump_write = optarg;
				break;
			case 'a':
				all_versions = 1;
				break;
			default:
				exit(1);
		}
	}

1204 1205 1206 1207
	if (kernel_read)
		read_dump(kernel_read, 1);
	if (module_read)
		read_dump(module_read, 0);
L
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1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233

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

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

		buf.pos = 0;

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

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

	if (dump_write)
		write_dump(dump_write);

	return 0;
}