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Subject[PATCH v4 4/4] selftest: Taint kernel when test module loaded
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Make any kselftest test module (using the kselftest_module framework)
taint the kernel with TAINT_TEST on module load.

Note that several selftests use kernel modules which are not based on
the kselftest_module framework, and so will not automatically taint the
kernel.

This can be done in two ways:
- Moving the module to the tools/testing directory. All modules under
this directory will taint the kernel.
- Adding the 'test' module property with:
MODULE_INFO(test, "Y")

Similarly, selftests which do not load modules into the kernel generally
should not taint the kernel (or possibly should only do so on failure),
as it's assumed that testing from user-space should be safe. Regardless,
they can write to /proc/sys/kernel/tainted if required.

Signed-off-by: David Gow <davidgow@google.com>
---

This still only covers a subset of selftest modules, but combined with
the modpost check for the tools/testing path, it should catch many
future tests. Others can be moved, adapted to use this framework, or
have MODULE_INFO(test, "Y") added. (Alas, I don't have the time to hunt
down all of the tests which don't do this at the moment.

No changes since v3:
https://lore.kernel.org/lkml/20220513083212.3537869-3-davidgow@google.com/

---
tools/testing/selftests/kselftest_module.h | 2 ++
1 file changed, 2 insertions(+)

diff --git a/tools/testing/selftests/kselftest_module.h b/tools/testing/selftests/kselftest_module.h
index e2ea41de3f35..226e616b82e0 100644
--- a/tools/testing/selftests/kselftest_module.h
+++ b/tools/testing/selftests/kselftest_module.h
@@ -3,6 +3,7 @@
#define __KSELFTEST_MODULE_H

#include <linux/module.h>
+#include <linux/panic.h>

/*
* Test framework for writing test modules to be loaded by kselftest.
@@ -41,6 +42,7 @@ static inline int kstm_report(unsigned int total_tests, unsigned int failed_test
static int __init __module##_init(void) \
{ \
pr_info("loaded.\n"); \
+ add_taint(TAINT_KUNIT, LOCKDEP_STILL_OK); \
selftest(); \
return kstm_report(total_tests, failed_tests, skipped_tests); \
} \
--
2.37.0.rc0.161.g10f37bed90-goog
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