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Date:   Tue, 22 Nov 2022 07:20:10 +0100
From:   Nicolas Schier <nicolas@fjasle.eu>
To:     Masahiro Yamada <masahiroy@kernel.org>
Cc:     linux-kbuild@vger.kernel.org,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nick Terrell <terrelln@fb.com>, Tom Rix <trix@redhat.com>,
        linux-kernel@vger.kernel.org, llvm@lists.linux.dev
Subject: Re: [PATCH v2 2/2] kbuild: warn objects shared among multiple modules
Message-ID: <Y3xqGhVXAladyxfg@bergen.fjasle.eu>
References: <20221118191551.66448-1-masahiroy@kernel.org>
 <20221118191551.66448-2-masahiroy@kernel.org>
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On Sat 19 Nov 2022 04:15:51 GMT, Masahiro Yamada wrote:
> If an object is shared among multiple modules, amd some of them are

amd -> and

Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

> configured as 'm', but the others as 'y', the shared object is built
> as modular, then linked to the modules and vmlinux. This is a potential
> issue because the expected CFLAGS are different between modules and
> builtins.
>=20
> Commit 637a642f5ca5 ("zstd: Fixing mixed module-builtin objects")
> reported that this could be even more fatal in some cases such as
> Clang LTO.
>=20
> That commit fixed lib/zlib/zstd_{compress,decompress}, but there are
> still more instances of breakage.
>=20
> This commit adds a W=3D1 warning for shared objects, so that the kbuild
> test robot, which provides build tests with W=3D1, will avoid a new
> breakage slipping in.
>=20
> Quick compile tests on v6.1-rc4 detected the following:
>=20
> scripts/Makefile.build:252: ./drivers/block/rnbd/Makefile: rnbd-common.o =
is added to multiple modules: rnbd-client rnbd-server
> scripts/Makefile.build:252: ./drivers/crypto/marvell/octeontx2/Makefile: =
cn10k_cpt.o is added to multiple modules: rvu_cptpf rvu_cptvf
> scripts/Makefile.build:252: ./drivers/crypto/marvell/octeontx2/Makefile: =
otx2_cptlf.o is added to multiple modules: rvu_cptpf rvu_cptvf
> scripts/Makefile.build:252: ./drivers/crypto/marvell/octeontx2/Makefile: =
otx2_cpt_mbox_common.o is added to multiple modules: rvu_cptpf rvu_cptvf
> scripts/Makefile.build:252: ./drivers/edac/Makefile: skx_common.o is adde=
d to multiple modules: i10nm_edac skx_edac
> scripts/Makefile.build:252: ./drivers/gpu/drm/bridge/imx/Makefile: imx-ld=
b-helper.o is added to multiple modules: imx8qm-ldb imx8qxp-ldb
> scripts/Makefile.build:252: ./drivers/mfd/Makefile: rsmu_core.o is added =
to multiple modules: rsmu-i2c rsmu-spi
> scripts/Makefile.build:252: ./drivers/mtd/tests/Makefile: mtd_test.o is a=
dded to multiple modules: mtd_nandbiterrs mtd_oobtest mtd_pagetest mtd_read=
test mtd_speedtest mtd_stresstest mtd_subpagetest mtd_torturetest
> scripts/Makefile.build:252: ./drivers/net/dsa/ocelot/Makefile: felix.o is=
 added to multiple modules: mscc_felix mscc_seville
> scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefi=
le: cn23xx_pf_device.o is added to multiple modules: liquidio liquidio_vf
> scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefi=
le: cn23xx_vf_device.o is added to multiple modules: liquidio liquidio_vf
> scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefi=
le: cn66xx_device.o is added to multiple modules: liquidio liquidio_vf
> scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefi=
le: cn68xx_device.o is added to multiple modules: liquidio liquidio_vf
> scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefi=
le: lio_core.o is added to multiple modules: liquidio liquidio_vf
> scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefi=
le: lio_ethtool.o is added to multiple modules: liquidio liquidio_vf
> scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefi=
le: octeon_device.o is added to multiple modules: liquidio liquidio_vf
> scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefi=
le: octeon_droq.o is added to multiple modules: liquidio liquidio_vf
> scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefi=
le: octeon_mailbox.o is added to multiple modules: liquidio liquidio_vf
> scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefi=
le: octeon_mem_ops.o is added to multiple modules: liquidio liquidio_vf
> scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefi=
le: octeon_nic.o is added to multiple modules: liquidio liquidio_vf
> scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefi=
le: request_manager.o is added to multiple modules: liquidio liquidio_vf
> scripts/Makefile.build:252: ./drivers/net/ethernet/cavium/liquidio/Makefi=
le: response_manager.o is added to multiple modules: liquidio liquidio_vf
> scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/dpaa2/Makefi=
le: dpaa2-mac.o is added to multiple modules: fsl-dpaa2-eth fsl-dpaa2-switch
> scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/dpaa2/Makefi=
le: dpmac.o is added to multiple modules: fsl-dpaa2-eth fsl-dpaa2-switch
> scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/enetc/Makefi=
le: enetc_cbdr.o is added to multiple modules: fsl-enetc fsl-enetc-vf
> scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/enetc/Makefi=
le: enetc_ethtool.o is added to multiple modules: fsl-enetc fsl-enetc-vf
> scripts/Makefile.build:252: ./drivers/net/ethernet/freescale/enetc/Makefi=
le: enetc.o is added to multiple modules: fsl-enetc fsl-enetc-vf
> scripts/Makefile.build:252: ./drivers/net/ethernet/hisilicon/hns3/Makefil=
e: hns3_common/hclge_comm_cmd.o is added to multiple modules: hclge hclgevf
> scripts/Makefile.build:252: ./drivers/net/ethernet/hisilicon/hns3/Makefil=
e: hns3_common/hclge_comm_rss.o is added to multiple modules: hclge hclgevf
> scripts/Makefile.build:252: ./drivers/net/ethernet/hisilicon/hns3/Makefil=
e: hns3_common/hclge_comm_tqp_stats.o is added to multiple modules: hclge h=
clgevf
> scripts/Makefile.build:252: ./drivers/net/ethernet/marvell/octeontx2/nic/=
Makefile: otx2_dcbnl.o is added to multiple modules: rvu_nicpf rvu_nicvf
> scripts/Makefile.build:252: ./drivers/net/ethernet/marvell/octeontx2/nic/=
Makefile: otx2_devlink.o is added to multiple modules: rvu_nicpf rvu_nicvf
> scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: cpsw_ale.=
o is added to multiple modules: keystone_netcp keystone_netcp_ethss ti_cpsw=
 ti_cpsw_new
> scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: cpsw_etht=
ool.o is added to multiple modules: ti_cpsw ti_cpsw_new
> scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: cpsw_priv=
=2Eo is added to multiple modules: ti_cpsw ti_cpsw_new
> scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: cpsw_sl.o=
 is added to multiple modules: ti_cpsw ti_cpsw_new
> scripts/Makefile.build:252: ./drivers/net/ethernet/ti/Makefile: davinci_c=
pdma.o is added to multiple modules: ti_cpsw ti_cpsw_new ti_davinci_emac
> scripts/Makefile.build:252: ./drivers/platform/x86/intel/int3472/Makefile=
: common.o is added to multiple modules: intel_skl_int3472_discrete intel_s=
kl_int3472_tps68470
> scripts/Makefile.build:252: ./sound/soc/codecs/Makefile: wcd-clsh-v2.o is=
 added to multiple modules: snd-soc-wcd9335 snd-soc-wcd934x snd-soc-wcd938x
>=20
> Once all the warnings are fixed, it can become an error irrespective of
> W=3D option.
>=20
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
>=20
> Changes in v2:
>   - Add drivers/block/rnbd/Makefile for commit log
>=20
>  scripts/Makefile.build | 6 ++++++
>  1 file changed, 6 insertions(+)
>=20
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 37cf88d076e8..799df12b53f3 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -222,6 +222,10 @@ endif
> =20
>  cmd_check_local_export =3D $(srctree)/scripts/check-local-export $@
> =20
> +ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
> +cmd_warn_shared_object =3D $(if $(word 2, $(modname-multi)),$(warning $(=
kbuild-file): $*.o is added to multiple modules: $(modname-multi)))
> +endif
> +
>  define rule_cc_o_c
>  	$(call cmd_and_fixdep,cc_o_c)
>  	$(call cmd,gen_ksymdeps)
> @@ -231,6 +235,7 @@ define rule_cc_o_c
>  	$(call cmd,gen_objtooldep)
>  	$(call cmd,gen_symversions_c)
>  	$(call cmd,record_mcount)
> +	$(call cmd,warn_shared_object)
>  endef
> =20
>  define rule_as_o_S
> @@ -239,6 +244,7 @@ define rule_as_o_S
>  	$(call cmd,check_local_export)
>  	$(call cmd,gen_objtooldep)
>  	$(call cmd,gen_symversions_S)
> +	$(call cmd,warn_shared_object)
>  endef
> =20
>  # Built-in and composite module parts
> --=20
> 2.34.1

--=20
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