Commit 2a66c312 authored by Masahiro Yamada's avatar Masahiro Yamada
Browse files

modpost: change the license of EXPORT_SYMBOL to bool type 



There were more EXPORT_SYMBOL types in the past. The following commits
removed unused ones.

 - f1c3d73e ("module: remove EXPORT_SYMBOL_GPL_FUTURE")
 - 36794822 ("module: remove EXPORT_UNUSED_SYMBOL*")

There are 3 remaining in enum export, but export_unknown does not make
any sense because we never expect such a situation like "we do not know
how it was exported".

If the symbol name starts with "__ksymtab_", but the section name
does not start with "___ksymtab+" or "___ksymtab_gpl+", it is not an
exported symbol.

It occurs when a variable starting with "__ksymtab_" is directly defined:

   int __ksymtab_foo;

Presumably, there is no practical issue for using such a weird variable
name (but there is no good reason for doing so, either).

Anyway, that is not an exported symbol. Setting export_unknown is not
the right thing to do. Do not call sym_add_exported() in this case.

With pointless export_unknown removed, the export type finally becomes
boolean (either EXPORT_SYMBOL or EXPORT_SYMBOL_GPL).

I renamed the field name to is_gpl_only. EXPORT_SYMBOL_GPL sets it true.
Only GPL-compatible modules can use it.

I removed the orphan comment, "How a symbol is exported", which is
unrelated to sec_mismatch_count. It is about enum export.
See commit bd5cbced ("kbuild: export-type enhancement to modpost.c")

Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
Reviewed-by: default avatarNicolas Schier <nicolas@fjasle.eu>
Tested-by: default avatarNathan Chancellor <nathan@kernel.org>
parent ce79c406

scripts/mod/modpost.c

+30 −78
Original line number Diff line number Diff line
@@ -30,7 +30,7 @@ static bool all_versions; 
static bool external_module;

/* Only warn about unresolved symbols */

static bool warn_unresolved;

/* How a symbol is exported */



static int sec_mismatch_count;

static bool sec_mismatch_warn_only = true;

/* ignore missing files */
@@ -47,12 +47,6 @@ static bool error_occurred; 
#define MAX_UNRESOLVED_REPORTS	10

static unsigned int nr_unresolved;



enum export {

	export_plain,

	export_gpl,

	export_unknown

};



/* In kernel, this size is defined in linux/module.h;

 * here we use Elf_Addr instead of long for covering cross-compile

 */
@@ -219,7 +213,7 @@ struct symbol { 
	bool crc_valid;

	bool weak;

	bool is_static;		/* true if symbol is not global */

	enum export  export;       /* Type of export */

	bool is_gpl_only;	/* exported by EXPORT_SYMBOL_GPL */

	char name[];

};
@@ -316,34 +310,6 @@ static void add_namespace(struct list_head *head, const char *namespace) 
	}

}



static const struct {

	const char *str;

	enum export export;

} export_list[] = {

	{ .str = "EXPORT_SYMBOL",            .export = export_plain },

	{ .str = "EXPORT_SYMBOL_GPL",        .export = export_gpl },

	{ .str = "(unknown)",                .export = export_unknown },

};





static const char *export_str(enum export ex)

{

	return export_list[ex].str;

}



static enum export export_no(const char *s)

{

	int i;



	if (!s)

		return export_unknown;

	for (i = 0; export_list[i].export != export_unknown; i++) {

		if (strcmp(export_list[i].str, s) == 0)

			return export_list[i].export;

	}

	return export_unknown;

}



static void *sym_get_data_by_offset(const struct elf_info *info,

				    unsigned int secindex, unsigned long offset)

{
@@ -374,18 +340,6 @@ static const char *sec_name(const struct elf_info *info, int secindex) 


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



static enum export export_from_secname(struct elf_info *elf, unsigned int sec)

{

	const char *secname = sec_name(elf, sec);



	if (strstarts(secname, "___ksymtab+"))

		return export_plain;

	else if (strstarts(secname, "___ksymtab_gpl+"))

		return export_gpl;

	else

		return export_unknown;

}



static void sym_update_namespace(const char *symname, const char *namespace)

{

	struct symbol *s = find_symbol(symname);
@@ -405,7 +359,7 @@ static void sym_update_namespace(const char *symname, const char *namespace) 
}



static struct symbol *sym_add_exported(const char *name, struct module *mod,

				       enum export export)

				       bool gpl_only)

{

	struct symbol *s = find_symbol(name);
@@ -417,7 +371,7 @@ static struct symbol *sym_add_exported(const char *name, struct module *mod, 


	s = alloc_symbol(name);

	s->module = mod;

	s->export    = export;

	s->is_gpl_only = gpl_only;

	list_add_tail(&s->list, &mod->exported_symbols);

	hash_add_symbol(s);
@@ -689,8 +643,6 @@ static void handle_modversion(const struct module *mod, 
static void handle_symbol(struct module *mod, struct elf_info *info,

			  const Elf_Sym *sym, const char *symname)

{

	const char *name;



	switch (sym->st_shndx) {

	case SHN_COMMON:

		if (strstarts(symname, "__gnu_lto_")) {
@@ -724,12 +676,15 @@ static void handle_symbol(struct module *mod, struct elf_info *info, 
	default:

		/* All exported symbols */

		if (strstarts(symname, "__ksymtab_")) {

			enum export export;

			const char *name, *secname;



			name = symname + strlen("__ksymtab_");

			export = export_from_secname(info,

						     get_secindex(info, sym));

			sym_add_exported(name, mod, export);

			secname = sec_name(info, get_secindex(info, sym));



			if (strstarts(secname, "___ksymtab_gpl+"))

				sym_add_exported(name, mod, true);

			else if (strstarts(secname, "___ksymtab+"))

				sym_add_exported(name, mod, false);

		}

		if (strcmp(symname, "init_module") == 0)

			mod->has_init = true;
@@ -2140,20 +2095,6 @@ void buf_write(struct buffer *buf, const char *s, int len) 
	buf->pos += len;

}



static void check_for_gpl_usage(enum export exp, const char *m, const char *s)

{

	switch (exp) {

	case export_gpl:

		error("GPL-incompatible module %s.ko uses GPL-only symbol '%s'\n",

		      m, s);

		break;

	case export_plain:

	case export_unknown:

		/* ignore */

		break;

	}

}



static void check_exports(struct module *mod)

{

	struct symbol *s, *exp;
@@ -2192,8 +2133,9 @@ static void check_exports(struct module *mod) 
			add_namespace(&mod->missing_namespaces, exp->namespace);

		}



		if (!mod->is_gpl_compatible)

			check_for_gpl_usage(exp->export, basename, exp->name);

		if (!mod->is_gpl_compatible && exp->is_gpl_only)

			error("GPL-incompatible module %s.ko uses GPL-only symbol '%s'\n",

			      basename, exp->name);

	}

}
@@ -2437,6 +2379,7 @@ static void read_dump(const char *fname) 
		unsigned int crc;

		struct module *mod;

		struct symbol *s;

		bool gpl_only;



		if (!(symname = strchr(line, '\t')))

			goto fail;
@@ -2454,12 +2397,22 @@ static void read_dump(const char *fname) 
		crc = strtoul(line, &d, 16);

		if (*symname == '\0' || *modname == '\0' || *d != '\0')

			goto fail;



		if (!strcmp(export, "EXPORT_SYMBOL_GPL")) {

			gpl_only = true;

		} else if (!strcmp(export, "EXPORT_SYMBOL")) {

			gpl_only = false;

		} else {

			error("%s: unknown license %s. skip", symname, export);

			continue;

		}



		mod = find_module(modname);

		if (!mod) {

			mod = new_module(modname);

			mod->from_dump = true;

		}

		s = sym_add_exported(symname, mod, export_no(export));

		s = sym_add_exported(symname, mod, gpl_only);

		s->is_static = false;

		sym_set_crc(symname, crc);

		sym_update_namespace(symname, namespace);
@@ -2481,9 +2434,9 @@ static void write_dump(const char *fname) 
		if (mod->from_dump)

			continue;

		list_for_each_entry(sym, &mod->exported_symbols, list) {

			buf_printf(&buf, "0x%08x\t%s\t%s\t%s\t%s\n",

			buf_printf(&buf, "0x%08x\t%s\t%s\tEXPORT_SYMBOL%s\t%s\n",

				   sym->crc, sym->name, mod->name,

				   export_str(sym->export),

				   sym->is_gpl_only ? "_GPL" : "",

				   sym->namespace ?: "");

		}

	}
@@ -2604,9 +2557,8 @@ int main(int argc, char **argv) 


		for (s = symbolhash[n]; s; s = s->next) {

			if (s->is_static)

				error("\"%s\" [%s] is a static %s\n",

				      s->name, s->module->name,

				      export_str(s->export));

				error("\"%s\" [%s] is a static EXPORT_SYMBOL\n",

				      s->name, s->module->name);

		}

	}