modpost.c

linux 内核源代码

	const char *namelist3 [] = {
		".unwind",  /* Sample: IA_64.unwind.exit.text */
		NULL
	};

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


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

	if (initexit_section_ref_ok(name))
		return 1;

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

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

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

	if (initexit_section_ref_ok(name))
		return 1;

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

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

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

	mod = new_module(modname);

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

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

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

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

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

	parse_elf_finish(&info);

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

#define SZ 500

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

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

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

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

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

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

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

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

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

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

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

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

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

	if (!modversions)
		return err;

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

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

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

	return err;
}

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

	err = 0;

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

		buf.pos = 0;

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

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

	if (dump_write)
		write_dump(dump_write);

	return err;
}