Re: [PATCH v1 2/2] kselftest: vm: add tests for memory-deny-write-execute

On Wed, Oct 26, 2022 at 04:04:57PM +0100, Joey Gouly wrote:

Add some tests to cover the new PR_SET_MDWE prctl.

Some comments below but they're all stylistic and let's not make perfect
be the enemy of the good here so

Reviewed-by: Mark Brown <broonie@kernel.org>

and we can iterate later rather than blocking anything on the testcase.

+#ifdef __aarch64__
+#define PROT_BTI      0x10            /* BTI guarded page */
+#endif

We should get this from the kernel headers shouldn't we?  We generally
rely on things getting pulled in from there rather than locally
defining.

+#define TEST1 "mmap(PROT_WRITE | PROT_EXEC)\n"
+#define TEST2 "mmap(PROT_WRITE); mprotect(PROT_EXEC)\n"
+#define TEST3 "mmap(PROT_EXEC); mprotect(PROT_EXEC | PROT_READ)\n"
+#define TEST4 "mmap(PROT_EXEC); mprotect(PROT_EXEC | PROT_BTI)\n"

+int test1(int mdwe_enabled)
+{

It feels like we could usefully make an array of

	struct test {
		int (*run)(bool mdwe_enabled);
		char *name;
	}

then we'd need fewer ifdefs, things could be more usefully named and
it'd be a bit easier to add new cases.

+#ifdef __aarch64__
+	ksft_set_plan(12);
+#else
+	ksft_set_plan(9);
+#endif

That'd just be ksft_test_plan(3 * ARRAY_SIZE(tests).

+	// First run the tests without MDWE
+	test_result(test1(0), TEST1);
+	test_result(test2(0), TEST2);
+	test_result(test3(0), TEST3);
+#ifdef __aarch64__
+	test_result(test4(0), TEST4);
+#endif

and these calls to the tests would all be iterating over the array.