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Message-ID: <CAMuHMdURtDNzzaoBM4DpEHKiDsgnA-7Yc9QO=5gsmwz9PHWK5w@mail.gmail.com>
Date: Sat, 7 Jan 2023 11:55:29 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Kees Cook <keescook@...omium.org>
Cc: Guenter Roeck <linux@...ck-us.net>,
Andrew Morton <akpm@...ux-foundation.org>,
Nathan Chancellor <nathan@...nel.org>,
linux-hardening@...r.kernel.org, David Gow <davidgow@...gle.com>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Josh Poimboeuf <jpoimboe@...nel.org>,
Miguel Ojeda <ojeda@...nel.org>,
Isabella Basso <isabbasso@...eup.net>,
Vlastimil Babka <vbabka@...e.cz>,
Dan Williams <dan.j.williams@...el.com>,
Rasmus Villemoes <linux@...musvillemoes.dk>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kunit: memcpy: Split slow memcpy tests into MEMCPY_SLOW_KUNIT_TEST
Hi Kees,
On Sat, Jan 7, 2023 at 5:02 AM Kees Cook <keescook@...omium.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@...ck-us.net>
> Link: https://lore.kernel.org/lkml/20221226195206.GA2626419@roeck-us.net
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Nathan Chancellor <nathan@...nel.org>
> Cc: linux-hardening@...r.kernel.org
> Signed-off-by: Kees Cook <keescook@...omium.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?
I guess that's why you made MEMCPY_SLOW_KUNIT_TEST tristate originally,
to have a separate module with the slow tests?
> + 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@...ux-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
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