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From:   Vlad Dronov <vdronov@redhat.com>
Date:   Mon, 4 Jul 2022 16:58:44 +0200
Message-ID: <CAMusb+QDk4CutzAGg-ZVmndnDh9N9q=HK1-Se=r6ebxPpdLp2g@mail.gmail.com>
Subject: Re: include/crypto/chacha.h:100: undefined reference to `chacha_crypt_arch'
To:     kernel test robot <lkp@intel.com>
Cc:     kbuild-all@lists.01.org, LKML <linux-kernel@vger.kernel.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Harald Freudenberger <freude@linux.ibm.com>
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Hi,

On Mon, Jul 4, 2022 at 4:35 PM Vlad Dronov <vdronov@redhat.com> wrote:
>
> Hi,
>
> On Sun, Jul 3, 2022 at 12:51 AM kernel test robot <lkp@intel.com> wrote:
> > ...
> > config: s390-buildonly-randconfig-r005-20220703 (https://download.01.or=
g/0day-ci/archive/20220703/202207030630.6SZVkrWf-lkp@intel.com/config)
> > ...
> >    s390-linux-ld: lib/crypto/chacha20poly1305.o: in function `chacha_cr=
ypt':
> > >> include/crypto/chacha.h:100: undefined reference to `chacha_crypt_ar=
ch'
> > >> s390-linux-ld: include/crypto/chacha.h:100: undefined reference to `=
chacha_crypt_arch'
> > ...
> > Kconfig warnings: (for reference only)
> >    WARNING: unmet direct dependencies detected for CRYPTO_LIB_CHACHA20P=
OLY1305
> >    Depends on (CRYPTO_ARCH_HAVE_LIB_CHACHA || !CRYPTO_ARCH_HAVE_LIB_CHA=
CHA && (CRYPTO_ARCH_HAVE_LIB_POLY1305 || !CRYPTO_ARCH_HAVE_LIB_POLY1305 && =
CRYPTO
>
> Ok, this is either weird or I do not understand how the Kconfig system wo=
rks.
>
> What I look at is CRYPTO_LIB_CHACHA20POLY1305 definition:
>
> [ lib/crypto/Kconfig ]
> config CRYPTO_LIB_CHACHA20POLY1305
>     tristate "ChaCha20-Poly1305 AEAD support (8-byte nonce library versio=
n)"
>     depends on CRYPTO_ARCH_HAVE_LIB_CHACHA || !CRYPTO_ARCH_HAVE_LIB_CHACH=
A
>     depends on CRYPTO_ARCH_HAVE_LIB_POLY1305 || !CRYPTO_ARCH_HAVE_LIB_POL=
Y1305
>     depends on CRYPTO
>
> and this test's random config (s390-buildonly-randconfig-r005-20220703):
>
> $ grep -e CRYPTO_LIB_CHACHA20POLY1305 -e CRYPTO_ARCH_HAVE_LIB_CHACHA
> -e CRYPTO_ARCH_HAVE_LIB_POLY1305 -e CRYPTO=3D config
> CONFIG_CRYPTO=3Dy
> CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA=3Dm
> CONFIG_CRYPTO_LIB_CHACHA20POLY1305=3Dy
> // missing CRYPTO_ARCH_HAVE_LIB_POLY1305 implies =3Dn (I guess?)
>
> I'm following the canonical "Kconfig Language" doc (
> https://www.kernel.org/doc/html/latest/kbuild/kconfig-language.html )
> which states:
>
> > - dependencies: =E2=80=9Cdepends on=E2=80=9D <expr>
> > This defines a dependency for this menu entry. If multiple dependencies=
 are defined, they are connected with =E2=80=98&&=E2=80=99.
>
> and
>
> >         '!' <expr>                           (6)
> >         <expr> '&&' <expr>                   (7)
> >         <expr> '||' <expr>                   (8)
> >
> > 6. Returns the result of (2-/expr/).
> > 7. Returns the result of min(/expr/, /expr/).
> > 8. Returns the result of max(/expr/, /expr/).
> > An expression can have a value of =E2=80=98n=E2=80=99, =E2=80=98m=E2=80=
=99 or =E2=80=98y=E2=80=99 (or 0, 1, 2 respectively for calculations).
>
> So calculating:
>
> (CRYPTO_ARCH_HAVE_LIB_CHACHA || !CRYPTO_ARCH_HAVE_LIB_CHACHA) &&
> (CRYPTO_ARCH_HAVE_LIB_POLY1305 || !CRYPTO_ARCH_HAVE_LIB_POLY1305) &&
> CRYPTO
>
> I find it equal to:
>
> (m || !m) && (n || !n) && y  =3D>  m && y && y  =3D>  m
>
> So CRYPTO_LIB_CHACHA20POLY1305 should be no higher than M, but it is
> =3DY in a config file =3D> weird :\ (or me wrong somewhere).
>
> WDYT?

Ok, I should have tested this beforehand. With the configs set as above:

CONFIG_CRYPTO=3Dy
CONFIG_CRYPTO_CHACHA20_X86_64=3Dm // implies the next line =3Dm
CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA=3Dm
CONFIG_CRYPTO_ARCH_HAVE_LIB_POLY1305 is not set // =3Dn

"make menuconfig" allows only =3Dn and =3Dm for CRYPTO_LIB_CHACHA20POLY1305=
 indeed.
So the test robot has fed an invalid config to a build process. Let me
forward this thread to
lkp@lists.01.org to report this issue.

Best regards,
Vladis Dronov | Red Hat, Inc. | The Core Kernel | Senior Software Engineer