+Cc rest of kunit from MAINTAINERS

On 1/7/23 11:55, Geert Uytterhoeven wrote:

Hi Kees,

On Sat, Jan 7, 2023 at 5:02 AM Kees Cook keescook@chromium.org wrote:

...

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 linux@roeck-us.net Link: https://lore.kernel.org/lkml/20221226195206.GA2626419@roeck-us.net Cc: Andrew Morton akpm@linux-foundation.org Cc: Nathan Chancellor nathan@kernel.org Cc: linux-hardening@vger.kernel.org Signed-off-by: Kees Cook keescook@chromium.org

Thanks for your patch!

...

--- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -2621,6 +2621,15 @@ config MEMCPY_KUNIT_TEST

      If unsure, say N.

+config MEMCPY_SLOW_KUNIT_TEST

•   tristate "Include exhaustive memcpy tests" if !KUNIT_ALL_TESTS
  

Why the tristate?

...

•   depends on MEMCPY_KUNIT_TEST
  

•   default KUNIT_ALL_TESTS
  

•   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.
  

config IS_SIGNED_TYPE_KUNIT_TEST tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS depends on KUNIT diff --git a/lib/memcpy_kunit.c b/lib/memcpy_kunit.c index 89128551448d..cc1f36335a9b 100644 --- a/lib/memcpy_kunit.c +++ b/lib/memcpy_kunit.c @@ -307,8 +307,12 @@ static void set_random_nonzero(struct kunit *test, u8 *byte) } }

-static void init_large(struct kunit *test) +static int 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");
  

So I can't make the slower tests available for when I need them, but not run them by default?

Indeed it seems weird to tie this to a config option without runtime override.

I guess that's why you made MEMCPY_SLOW_KUNIT_TEST tristate originally, to have a separate module with the slow tests?

On the other hand I can imagine requiring a separate module for slow tests would lead to more churn - IIUC there would need to be two files instead of memcpy_kunit.c, possibly a duplicated boilerplate code (or another shared .c file).

So the idea is to have a generic way to mark some tests as slow and a way to opt-in/opt-out for those when running the tests. Maybe KUnit folks already have such mechanism or have an idea how to implement that.

...

•           return -EBUSY;
  

•   }
  
    /* Get many bit patterns. */
    get_random_bytes(large_src, ARRAY_SIZE(large_src));
  

Gr{oetje,eeting}s,

                    Geert

-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds