[PATCH 2/2] modpost: return error if module is missing ns imports and MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n

Jessica Yu
2020-02-25T17:35:38Z

Currently when CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n, modpost only warns
when a module is missing namespace imports. Under this configuration, such a module
cannot be loaded into the kernel anyway, as the module loader would reject it.
We might as well return a build error when a module is missing namespace imports
under CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n, so that the build
warning does not go ignored/unnoticed.

Signed-off-by: Jessica Yu <jeyu@kernel.org>
---
scripts/Makefile.modpost | 15 ++++++++-------
scripts/mod/modpost.c | 14 +++++++++++---
2 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
index b4d3f2d122ac..957eed6a17a5 100644
--- a/scripts/Makefile.modpost
+++ b/scripts/Makefile.modpost
@@ -46,13 +46,14 @@ include scripts/Kbuild.include
kernelsymfile := $(objtree)/Module.symvers
modulesymfile := $(firstword $(KBUILD_EXTMOD))/Module.symvers

-MODPOST = scripts/mod/modpost \
- $(if $(CONFIG_MODVERSIONS),-m) \
- $(if $(CONFIG_MODULE_SRCVERSION_ALL),-a) \
- $(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile) \
- $(if $(KBUILD_EXTMOD),$(addprefix -e ,$(KBUILD_EXTRA_SYMBOLS))) \
- $(if $(KBUILD_EXTMOD),-o $(modulesymfile)) \
- $(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E) \
+MODPOST = scripts/mod/modpost \
+ $(if $(CONFIG_MODVERSIONS),-m) \
+ $(if $(CONFIG_MODULE_SRCVERSION_ALL),-a) \
+ $(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile) \
+ $(if $(KBUILD_EXTMOD),$(addprefix -e ,$(KBUILD_EXTRA_SYMBOLS))) \
+ $(if $(KBUILD_EXTMOD),-o $(modulesymfile)) \
+ $(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E) \
+ $(if $(CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS)$(KBUILD_NSDEPS),-N) \
$(if $(KBUILD_MODPOST_WARN),-w)

ifdef MODPOST_VMLINUX
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index e2805fbeb99f..9ae2b1c9a870 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -39,6 +39,8 @@ static int sec_mismatch_count = 0;
static int sec_mismatch_fatal = 0;
/* ignore missing files */
static int ignore_missing_files;
+/* If set to 1, only warn (instead of error) about missing ns imports */
+static int allow_missing_ns_imports = 0;

enum export {
export_plain, export_unused, export_gpl,
@@ -2211,8 +2213,11 @@ static int check_exports(struct module *mod)

if (exp->namespace &&
!module_imports_namespace(mod, exp->namespace)) {
- warn("module %s uses symbol %s from namespace %s, but does not import it.\n",
- basename, exp->name, exp->namespace);
+ warn_unless(!allow_missing_ns_imports,
+ "module %s uses symbol %s from namespace %s, but does not import it.\n",
+ basename, exp->name, exp->namespace);
+ if (!allow_missing_ns_imports)
+ err = 1;
add_namespace(&mod->missing_namespaces, exp->namespace);
}

@@ -2555,7 +2560,7 @@ int main(int argc, char **argv)
struct ext_sym_list *extsym_iter;
struct ext_sym_list *extsym_start = NULL;

- while ((opt = getopt(argc, argv, "i:e:mnsT:o:awEd:")) != -1) {
+ while ((opt = getopt(argc, argv, "i:e:mnsT:o:awENd:")) != -1) {
switch (opt) {
case 'i':
kernel_read = optarg;
@@ -2593,6 +2598,9 @@ int main(int argc, char **argv)
case 'E':
sec_mismatch_fatal = 1;
break;
+ case 'N':
+ allow_missing_ns_imports = 1;
+ break;
case 'd':
missing_namespace_deps = optarg;
break;
--
2.16.4