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Commit c96fca21 authored by Sam Ravnborg's avatar Sam Ravnborg
Browse files

kbuild: warn when a moduled uses a symbol marked UNUSED 



We now have infrastructure in place to mark an EXPORTed symbol
as unused. So the natural next step is to warn during buildtime when
a module uses a symbol marked UNUSED.

Signed-off-by: default avatarSam Ravnborg <sam@ravnborg.org>
parent 534b89a9

scripts/mod/modpost.c

+62 −23
Original line number Diff line number Diff line
@@ -24,7 +24,10 @@ static int all_versions = 0; 
/* If we are modposting external module set to 1 */

static int external_module = 0;

/* How a symbol is exported */

enum export {export_plain, export_gpl, export_gpl_future, export_unknown};

enum export {

	export_plain,      export_unused,     export_gpl,

	export_unused_gpl, export_gpl_future, export_unknown

};



void fatal(const char *fmt, ...)

{
@@ -191,7 +194,9 @@ static struct { 
	enum export export;

} export_list[] = {

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

	{ .str = "EXPORT_UNUSED_SYMBOL",     .export = export_unused },

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

	{ .str = "EXPORT_UNUSED_SYMBOL_GPL", .export = export_unused_gpl },

	{ .str = "EXPORT_SYMBOL_GPL_FUTURE", .export = export_gpl_future },

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

};
@@ -218,8 +223,12 @@ static enum export export_from_sec(struct elf_info *elf, Elf_Section sec) 
{

	if (sec == elf->export_sec)

		return export_plain;

	else if (sec == elf->export_unused_sec)

		return export_unused;

	else if (sec == elf->export_gpl_sec)

		return export_gpl;

	else if (sec == elf->export_unused_gpl_sec)

		return export_unused_gpl;

	else if (sec == elf->export_gpl_future_sec)

		return export_gpl_future;

	else
@@ -368,8 +377,12 @@ static void parse_elf(struct elf_info *info, const char *filename) 
			info->modinfo_len = sechdrs[i].sh_size;

		} else if (strcmp(secname, "__ksymtab") == 0)

			info->export_sec = i;

		else if (strcmp(secname, "__ksymtab_unused") == 0)

			info->export_unused_sec = i;

		else if (strcmp(secname, "__ksymtab_gpl") == 0)

			info->export_gpl_sec = i;

		else if (strcmp(secname, "__ksymtab_unused_gpl") == 0)

			info->export_unused_gpl_sec = i;

		else if (strcmp(secname, "__ksymtab_gpl_future") == 0)

			info->export_gpl_future_sec = i;
@@ -1087,38 +1100,64 @@ void buf_write(struct buffer *buf, const char *s, int len) 
	buf->pos += len;

}



void check_license(struct module *mod)

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;

		if (mod->gpl_compatible == 1) {

			/* GPL-compatible modules may use all symbols */

			continue;

		}

		exp = find_symbol(s->name);

		if (!exp || exp->module == mod)

			continue;

		basename = strrchr(mod->name, '/');

		if (basename)

			basename++;

		switch (exp->export) {

			case export_gpl:

				fatal("modpost: GPL-incompatible module %s "

				      "uses GPL-only symbol '%s'\n",

				 basename ? basename : mod->name,

				exp->name);

				break;

			case export_gpl_future:

				warn("modpost: GPL-incompatible module %s "

				      "uses future GPL-only symbol '%s'\n",

				      basename ? basename : mod->name,

				      exp->name);

				break;

			case export_plain: /* ignore */ break;

			case export_unknown: /* ignore */ break;

		}

		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);

        }

}
@@ -1399,7 +1438,7 @@ int main(int argc, char **argv) 
	for (mod = modules; mod; mod = mod->next) {

		if (mod->skip)

			continue;

		check_license(mod);

		check_exports(mod);

	}



	for (mod = modules; mod; mod = mod->next) {

scripts/mod/modpost.h

+2 −0
Original line number Diff line number Diff line
@@ -117,7 +117,9 @@ struct elf_info { 
	Elf_Sym      *symtab_start;

	Elf_Sym      *symtab_stop;

	Elf_Section  export_sec;

	Elf_Section  export_unused_sec;

	Elf_Section  export_gpl_sec;

	Elf_Section  export_unused_gpl_sec;

	Elf_Section  export_gpl_future_sec;

	const char   *strtab;

	char	     *modinfo;