modpost.c 36.3 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"
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#include "../../include/linux/license.h"
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/* 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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/* Only warn about unresolved symbols */
static int warn_unresolved = 0;
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/* How a symbol is exported */
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enum export {
	export_plain,      export_unused,     export_gpl,
	export_unused_gpl, export_gpl_future, export_unknown
};
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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;
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	mod->gpl_compatible = -1;
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	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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	enum export  export;       /* Type of export */
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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,
				 enum export export)
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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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	new->export = export;
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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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static struct {
	const char *str;
	enum export export;
} export_list[] = {
	{ .str = "EXPORT_SYMBOL",            .export = export_plain },
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	{ .str = "EXPORT_UNUSED_SYMBOL",     .export = export_unused },
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	{ .str = "EXPORT_SYMBOL_GPL",        .export = export_gpl },
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	{ .str = "EXPORT_UNUSED_SYMBOL_GPL", .export = export_unused_gpl },
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	{ .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;
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	if (!s)
		return export_unknown;
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	for (i = 0; export_list[i].export != export_unknown; i++) {
		if (strcmp(export_list[i].str, s) == 0)
			return export_list[i].export;
	}
	return export_unknown;
}

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

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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,
				       enum export export)
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{
	struct symbol *s = find_symbol(name);

	if (!s) {
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		s = new_symbol(name, mod, export);
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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");
		}
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	}
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	s->preloaded = 0;
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	s->vmlinux   = is_vmlinux(mod->name);
	s->kernel    = 0;
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	s->export    = export;
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	return s;
}

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

	if (!s)
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		s = new_symbol(name, mod, export);
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	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);
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		exit(1);
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	}
	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;
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		const char *secname;
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		if (sechdrs[i].sh_offset > info->size)
			goto truncated;
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		secname = secstrings + sechdrs[i].sh_name;
		if (strcmp(secname, ".modinfo") == 0) {
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			info->modinfo = (void *)hdr + sechdrs[i].sh_offset;
			info->modinfo_len = sechdrs[i].sh_size;
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		} else if (strcmp(secname, "__ksymtab") == 0)
			info->export_sec = i;
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		else if (strcmp(secname, "__ksymtab_unused") == 0)
			info->export_unused_sec = i;
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		else if (strcmp(secname, "__ksymtab_gpl") == 0)
			info->export_gpl_sec = i;
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		else if (strcmp(secname, "__ksymtab_unused_gpl") == 0)
			info->export_unused_gpl_sec = i;
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		else if (strcmp(secname, "__ksymtab_gpl_future") == 0)
			info->export_gpl_future_sec = i;

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		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;

 truncated:
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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     MODULE_SYMBOL_PREFIX "__crc_"
#define KSYMTAB_PFX MODULE_SYMBOL_PREFIX "__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;
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	enum export export = export_from_sec(info, sym->st_shndx);
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	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,
					export);
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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,
					export);
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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;
}

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

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

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

{
	return get_next_modinfo(modinfo, modinfo_len, tag, 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:
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 *   Many drivers utilise a *driver container with references to
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 *   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:
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 *   tosec   = .init.text | .exit.text | .init.data
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 *   fromsec = .data
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 *   atsym = *driver, *_template, *_sht, *_ops, *_probe, *probe_one
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 **/
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static int secref_whitelist(const char *modname, const char *tosec,
			    const char *fromsec, const char *atsym)
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{
	int f1 = 1, f2 = 1;
	const char **s;
	const char *pat2sym[] = {
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		"driver",
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		"_template", /* scsi uses *_template a lot */
		"_sht",      /* scsi also used *_sht to some extent */
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		"_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) &&
	    (strcmp(tosec, ".init.data") != 0))
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		f2 = 0;
	if (strcmp(fromsec, ".data") != 0)
		f2 = 0;

	for (s = pat2sym; *s; s++)
		if (strrcmp(atsym, *s) == 0)
			f1 = 1;
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	if (f1 && f2)
		return 1;
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	/* Whitelist all references from .pci_fixup section if vmlinux */
	if (is_vmlinux(modname)) {
		if ((strcmp(fromsec, ".pci_fixup") == 0) &&
		    (strcmp(tosec, ".init.text") == 0))
		return 1;
	}
632
	return 0;
633 634
}

635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657
/**
 * 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;
}

658
/*
659 660 661 662
 * 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.
663 664 665 666 667 668 669 670 671 672 673
 **/
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;
674

675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690
	*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;
			}
691 692 693 694 695 696
			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;
			}
697 698 699 700 701 702 703
		}
		else
		{
			if ((sym->st_value - addr) < afterdiff) {
				afterdiff = sym->st_value - addr;
				*after = sym;
			}
704 705 706 707 708 709
			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;
			}
710 711 712 713 714 715 716
		}
	}
}

/**
 * Print a warning about a section mismatch.
 * Try to find symbols near it so user can find it.
717
 * Check whitelist before warning - it may be a false positive.
718 719 720 721
 **/
static void warn_sec_mismatch(const char *modname, const char *fromsec,
			      struct elf_info *elf, Elf_Sym *sym, Elf_Rela r)
{
722 723 724
	const char *refsymname = "";
	Elf_Sym *before, *after;
	Elf_Sym *refsym;
725 726 727 728 729
	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;
730

731 732
	find_symbols_between(elf, r.r_offset, fromsec, &before, &after);

733 734 735
	refsym = find_elf_symbol(elf, r.r_addend, sym);
	if (refsym && strlen(elf->strtab + refsym->st_name))
		refsymname = elf->strtab + refsym->st_name;
736 737

	/* check whitelist - we may ignore it */
738
	if (before &&
739 740
	    secref_whitelist(modname, secname, fromsec,
			     elf->strtab + before->st_name))
741
		return;
742

743
	if (before && after) {
744 745 746
		warn("%s - Section mismatch: reference to %s:%s from %s "
		     "between '%s' (at offset 0x%llx) and '%s'\n",
		     modname, secname, refsymname, fromsec,
747
		     elf->strtab + before->st_name,
748
		     (long long)r.r_offset,
749 750
		     elf->strtab + after->st_name);
	} else if (before) {
751 752
		warn("%s - Section mismatch: reference to %s:%s from %s "
		     "after '%s' (at offset 0x%llx)\n",
753
		     modname, secname, refsymname, fromsec,
754
		     elf->strtab + before->st_name,
755
		     (long long)r.r_offset);
756
	} else if (after) {
757 758
		warn("%s - Section mismatch: reference to %s:%s from %s "
		     "before '%s' (at offset -0x%llx)\n",
759
		     modname, secname, refsymname, fromsec,
760
		     elf->strtab + after->st_name,
761
		     (long long)r.r_offset);
762
	} else {
763 764 765 766
		warn("%s - Section mismatch: reference to %s:%s from %s "
		     "(offset 0x%llx)\n",
		     modname, secname, fromsec, refsymname,
		     (long long)r.r_offset);
767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792
	}
}

/**
 * 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;
793

794 795
	/* Walk through all sections */
	for (i = 0; i < hdr->e_shnum; i++) {
796 797 798
		const char *name = secstrings + sechdrs[i].sh_name;
		const char *secname;
		Elf_Rela r;
799
		unsigned int r_sym;
800
		/* We want to process only relocation sections and not .init */
801 802 803 804 805 806 807
		if (sechdrs[i].sh_type == SHT_RELA) {
			Elf_Rela *rela;
			Elf_Rela *start = (void *)hdr + sechdrs[i].sh_offset;
			Elf_Rela *stop  = (void*)start + sechdrs[i].sh_size;
			name += strlen(".rela");
			if (section_ref_ok(name))
				continue;
808

809 810
			for (rela = start; rela < stop; rela++) {
				r.r_offset = TO_NATIVE(rela->r_offset);
811 812 813 814 815 816 817 818 819 820 821 822
#if KERNEL_ELFCLASS == ELFCLASS64
				if (hdr->e_machine == EM_MIPS) {
					r_sym = ELF64_MIPS_R_SYM(rela->r_info);
					r_sym = TO_NATIVE(r_sym);
				} 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
823
				r.r_addend = TO_NATIVE(rela->r_addend);
824
				sym = elf->symtab_start + r_sym;
825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840
				/* Skip special sections */
				if (sym->st_shndx >= SHN_LORESERVE)
					continue;

				secname = secstrings +
					sechdrs[sym->st_shndx].sh_name;
				if (section(secname))
					warn_sec_mismatch(modname, name,
							  elf, sym, r);
			}
		} else if (sechdrs[i].sh_type == SHT_REL) {
			Elf_Rel *rel;
			Elf_Rel *start = (void *)hdr + sechdrs[i].sh_offset;
			Elf_Rel *stop  = (void*)start + sechdrs[i].sh_size;
			name += strlen(".rel");
			if (section_ref_ok(name))
841 842
				continue;

843 844
			for (rel = start; rel < stop; rel++) {
				r.r_offset = TO_NATIVE(rel->r_offset);
845 846 847 848 849 850 851 852 853 854 855 856
#if KERNEL_ELFCLASS == ELFCLASS64
				if (hdr->e_machine == EM_MIPS) {
					r_sym = ELF64_MIPS_R_SYM(rel->r_info);
					r_sym = TO_NATIVE(r_sym);
				} 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
857
				r.r_addend = 0;
858
				sym = elf->symtab_start + r_sym;
859 860 861 862 863 864 865 866 867 868
				/* Skip special sections */
				if (sym->st_shndx >= SHN_LORESERVE)
					continue;

				secname = secstrings +
					sechdrs[sym->st_shndx].sh_name;
				if (section(secname))
					warn_sec_mismatch(modname, name,
							  elf, sym, r);
			}
869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890
		}
	}
}

/**
 * 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.
891
 *
892 893 894 895 896
 * 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:
897
 *
898 899 900 901 902 903 904 905 906 907 908 909
 * 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",
910 911
		".opd",   /* see comment [OPD] at exit_section_ref_ok() */
		".toc1",  /* used by ppc64 */
912 913 914
		".stab",
		".rodata",
		".text.lock",
915
		"__bug_table", /* used by powerpc for BUG() */
916 917 918 919
		".pci_fixup_header",
		".pci_fixup_final",
		".pdr",
		"__param",
920 921
		"__ex_table",
		".fixup",
922
		".smp_locks",
923
		".plt",  /* seen on ARCH=um build on x86_64. Harmless */
924 925 926 927 928 929 930 931 932 933
		NULL
	};
	/* Start of section names */
	const char *namelist2[] = {
		".init.",
		".altinstructions",
		".eh_frame",
		".debug",
		NULL
	};
934 935 936 937 938 939
	/* part of section name */
	const char *namelist3 [] = {
		".unwind",  /* sample: IA_64.unwind.init.text */
		NULL
	};

940 941 942
	for (s = namelist1; *s; s++)
		if (strcmp(*s, name) == 0)
			return 1;
943
	for (s = namelist2; *s; s++)
944 945
		if (strncmp(*s, name, strlen(*s)) == 0)
			return 1;
946
	for (s = namelist3; *s; s++)
947
		if (strstr(name, *s) != NULL)
948
			return 1;
949 950
	if (strrcmp(name, ".init") == 0)
		return 1;
951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967
	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;
968

969 970 971 972
}

/*
 * Identify sections from which references to a .exit section is OK.
973
 *
974 975 976 977
 * [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.
978
 * [.rodata] like for .init.text we ignore .rodata references -same reason
979 980 981 982 983 984 985 986 987
 **/
static int exit_section_ref_ok(const char *name)
{
	const char **s;
	/* Absolute section names */
	const char *namelist1[] = {
		".exit.text",
		".exit.data",
		".init.text",
988
		".rodata",
989
		".opd", /* See comment [OPD] */
990
		".toc1",  /* used by ppc64 */
991 992
		".altinstructions",
		".pdr",
993
		"__bug_table", /* used by powerpc for BUG() */
994 995 996
		".exitcall.exit",
		".eh_frame",
		".stab",
997 998
		"__ex_table",
		".fixup",
999
		".smp_locks",
1000
		".plt",  /* seen on ARCH=um build on x86_64. Harmless */
1001 1002 1003 1004 1005 1006 1007
		NULL
	};
	/* Start of section names */
	const char *namelist2[] = {
		".debug",
		NULL
	};
1008 1009 1010 1011 1012
	/* part of section name */
	const char *namelist3 [] = {
		".unwind",  /* Sample: IA_64.unwind.exit.text */
		NULL
	};
1013

1014 1015 1016
	for (s = namelist1; *s; s++)
		if (strcmp(*s, name) == 0)
			return 1;
1017
	for (s = namelist2; *s; s++)
1018 1019
		if (strncmp(*s, name, strlen(*s)) == 0)
			return 1;
1020
	for (s = namelist3; *s; s++)
1021
		if (strstr(name, *s) != NULL)
1022
			return 1;
1023 1024 1025
	return 0;
}

1026
static void read_symbols(char *modname)
L
Linus Torvalds 已提交
1027 1028 1029
{
	const char *symname;
	char *version;
1030
	char *license;
L
Linus Torvalds 已提交
1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045
	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;
	}

1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057
	license = get_modinfo(info.modinfo, info.modinfo_len, "license");
	while (license) {
		if (license_is_gpl_compatible(license))
			mod->gpl_compatible = 1;
		else {
			mod->gpl_compatible = 0;
			break;
		}
		license = get_next_modinfo(info.modinfo, info.modinfo_len,
					   "license", license);
	}

L
Linus Torvalds 已提交
1058 1059 1060 1061 1062 1063
	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);
	}
1064 1065
	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
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

	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 */

1091 1092
void __attribute__((format(printf, 2, 3))) buf_printf(struct buffer *buf,
						      const char *fmt, ...)
L
Linus Torvalds 已提交
1093 1094 1095 1096
{
	char tmp[SZ];
	int len;
	va_list ap;
1097

L
Linus Torvalds 已提交
1098 1099
	va_start(ap, fmt);
	len = vsnprintf(tmp, SZ, fmt, ap);
1100
	buf_write(buf, tmp, len);
L
Linus Torvalds 已提交
1101 1102 1103
	va_end(ap);
}

1104
void buf_write(struct buffer *buf, const char *s, int len)
L
Linus Torvalds 已提交
1105 1106
{
	if (buf->size - buf->pos < len) {
1107
		buf->size += len + SZ;
L
Linus Torvalds 已提交
1108 1109 1110 1111 1112 1113
		buf->p = realloc(buf->p, buf->size);
	}
	strncpy(buf->p + buf->pos, s, len);
	buf->pos += len;
}

1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155
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)
1156 1157 1158 1159
{
	struct symbol *s, *exp;

	for (s = mod->unres; s; s = s->next) {
A
Andrew Morton 已提交
1160
		const char *basename;
1161 1162 1163
		exp = find_symbol(s->name);
		if (!exp || exp->module == mod)
			continue;
A
Andrew Morton 已提交
1164
		basename = strrchr(mod->name, '/');
1165 1166
		if (basename)
			basename++;
1167 1168 1169 1170 1171
		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);
1172 1173 1174
        }
}

1175 1176 1177 1178
/**
 * Header for the generated file
 **/
static void add_header(struct buffer *b, struct module *mod)
L
Linus Torvalds 已提交
1179 1180 1181 1182 1183 1184 1185 1186 1187
{
	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");
1188
	buf_printf(b, " .name = KBUILD_MODNAME,\n");
L
Linus Torvalds 已提交
1189 1190 1191 1192 1193 1194 1195 1196 1197
	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");
}

1198 1199 1200
/**
 * Record CRCs for unresolved symbols
 **/
1201
static int add_versions(struct buffer *b, struct module *mod)
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{
	struct symbol *s, *exp;
1204
	int err = 0;
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	for (s = mod->unres; s; s = s->next) {
		exp = find_symbol(s->name);
		if (!exp || exp->module == mod) {
1209
			if (have_vmlinux && !s->weak) {
1210 1211
				warn("\"%s\" [%s.ko] undefined!\n",
				     s->name, mod->name);
1212 1213
				err = warn_unresolved ? 0 : 1;
			}
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			continue;
		}
		s->module = exp->module;
		s->crc_valid = exp->crc_valid;
		s->crc = exp->crc;
	}

	if (!modversions)
1222
		return err;
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	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) {
1234
			warn("\"%s\" [%s.ko] has no CRC!\n",
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				s->name, mod->name);
			continue;
		}
		buf_printf(b, "\t{ %#8x, \"%s\" },\n", s->crc, s->name);
	}

	buf_printf(b, "};\n");
1242 1243

	return err;
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}

1246 1247
static void add_depends(struct buffer *b, struct module *mod,
			struct module *modules)
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{
	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");
}

1277
static void add_srcversion(struct buffer *b, struct module *mod)
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{
	if (mod->srcversion[0]) {
		buf_printf(b, "\n");
		buf_printf(b, "MODULE_INFO(srcversion, \"%s\");\n",
			   mod->srcversion);
	}
}

1286
static void write_if_changed(struct buffer *b, const char *fname)
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{
	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);
}

1330
/* parse Module.symvers file. line format:
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 * 0x12345678<tab>symbol<tab>module[[<tab>export]<tab>something]
1332
 **/
1333
static void read_dump(const char *fname, unsigned int kernel)
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{
	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))) {
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		char *symname, *modname, *d, *export, *end;
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		unsigned int crc;
		struct module *mod;
1347
		struct symbol *s;
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		if (!(symname = strchr(line, '\t')))
			goto fail;
		*symname++ = '\0';
		if (!(modname = strchr(symname, '\t')))
			goto fail;
		*modname++ = '\0';
1355
		if ((export = strchr(modname, '\t')) != NULL)
1356
			*export++ = '\0';
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		if (export && ((end = strchr(export, '\t')) != NULL))
			*end = '\0';
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		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;
		}
1370
		s = sym_add_exported(symname, mod, export_no(export));
1371 1372
		s->kernel    = kernel;
		s->preloaded = 1;
1373
		sym_update_crc(symname, mod, crc, export_no(export));
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	}
	return;
fail:
	fatal("parse error in symbol dump file\n");
}

1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391
/* 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;
}
1392

1393
static void write_dump(const char *fname)
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{
	struct buffer buf = { };
	struct symbol *symbol;
	int n;

	for (n = 0; n < SYMBOL_HASH_SIZE ; n++) {
		symbol = symbolhash[n];
		while (symbol) {
1402
			if (dump_sym(symbol))
1403
				buf_printf(&buf, "0x%08x\t%s\t%s\t%s\n",
1404
					symbol->crc, symbol->name,
1405 1406
					symbol->module->name,
					export_str(symbol->export));
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			symbol = symbol->next;
		}
	}
	write_if_changed(&buf, fname);
}

1413
int main(int argc, char **argv)
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{
	struct module *mod;
	struct buffer buf = { };
	char fname[SZ];
1418 1419
	char *kernel_read = NULL, *module_read = NULL;
	char *dump_write = NULL;
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	int opt;
1421
	int err;
L
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1423
	while ((opt = getopt(argc, argv, "i:I:mo:aw")) != -1) {
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		switch(opt) {
			case 'i':
1426 1427 1428 1429 1430
				kernel_read = optarg;
				break;
			case 'I':
				module_read = optarg;
				external_module = 1;
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				break;
			case 'm':
				modversions = 1;
				break;
			case 'o':
				dump_write = optarg;
				break;
			case 'a':
				all_versions = 1;
				break;
1441 1442 1443
			case 'w':
				warn_unresolved = 1;
				break;
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			default:
				exit(1);
		}
	}

1449 1450 1451 1452
	if (kernel_read)
		read_dump(kernel_read, 1);
	if (module_read)
		read_dump(module_read, 0);
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	while (optind < argc) {
		read_symbols(argv[optind++]);
	}

1458 1459 1460
	for (mod = modules; mod; mod = mod->next) {
		if (mod->skip)
			continue;
1461
		check_exports(mod);
1462 1463
	}

1464 1465
	err = 0;

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

		buf.pos = 0;

		add_header(&buf, mod);
1473
		err |= add_versions(&buf, mod);
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		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);

1485
	return err;
L
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}