kunit: memcpy: Split slow memcpy tests into MEMCPY_SLOW_KUNIT_TEST

Since the long memcpy tests may stall a system for tens of seconds
in virtualized architecture environments, split those tests off under
CONFIG_MEMCPY_SLOW_KUNIT_TEST so they can be separately disabled.

Reported-by: Guenter Roeck <[e-mail]>
Link: https://lore.kernel.org/lkml/[e-mail]
Reviewed-by: Nick Desaulniers <[e-mail]>
Reviewed-and-tested-by: Guenter Roeck <[e-mail]>
Reviewed-by: David Gow <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Cc: Nathan Chancellor <[e-mail]>
Cc: [e-mail]
Signed-off-by: Kees Cook <[e-mail]>

lib/Kconfig.debug

···
 
 	  If unsure, say N.
 
+config MEMCPY_SLOW_KUNIT_TEST
+	bool "Include exhaustive memcpy tests"
+	depends on MEMCPY_KUNIT_TEST
+	default y
+	help
+	  Some memcpy tests are quite exhaustive in checking for overlaps
+	  and bit ranges. These can be very slow, so they are split out
+	  as a separate config, in case they need to be disabled.
+
 config IS_SIGNED_TYPE_KUNIT_TEST
 	tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
 	depends on KUNIT

lib/memcpy_kunit.c

···
 
 static void init_large(struct kunit *test)
 {
+	if (!IS_ENABLED(CONFIG_MEMCPY_SLOW_KUNIT_TEST))
+		kunit_skip(test, "Slow test skipped. Enable with CONFIG_MEMCPY_SLOW_KUNIT_TEST=y");
 
 	/* Get many bit patterns. */
 	get_random_bytes(large_src, ARRAY_SIZE(large_src));