From: Kees Cook <keescook@chromium.org>
To: Masahiro Yamada <masahiroy@kernel.org>
Cc: linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
Emese Revfy <re.emese@gmail.com>,
Michal Marek <michal.lkml@markovi.net>,
kernel-hardening@lists.openwall.com
Subject: Re: [PATCH] gcc-plugins: drop support for GCC <= 4.7
Date: Sun, 29 Mar 2020 21:27:22 -0700 [thread overview]
Message-ID: <202003292126.5105600A@keescook> (raw)
In-Reply-To: <20200329110832.19961-1-masahiroy@kernel.org>
On Sun, Mar 29, 2020 at 08:08:32PM +0900, Masahiro Yamada wrote:
> Nobody was opposed to raising minimum GCC version to 4.8 [1]
> So, we will drop GCC <= 4.7 support sooner or later.
>
> We always use C++ compiler for building plugins for GCC >= 4.8.
>
> This commit drops the plugin support for GCC <= 4.7 a bit earlier,
> which allows us to dump lots of code.
>
> [1] https://lkml.org/lkml/2020/1/23/545
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Thanks for getting this cleaned up! I look forward to the 4.8 version
bump. :)
Acked-by: Kees Cook <keescook@chromium.org>
-Kees
> ---
>
> This patch depends on this:
> https://patchwork.kernel.org/patch/11456871/
>
> scripts/Kconfig.include | 3 --
> scripts/Makefile.build | 2 +-
> scripts/Makefile.clean | 1 -
> scripts/Makefile.host | 23 +--------------
> scripts/gcc-plugin.sh | 55 +++---------------------------------
> scripts/gcc-plugins/Kconfig | 12 ++------
> scripts/gcc-plugins/Makefile | 21 ++++----------
> 7 files changed, 14 insertions(+), 103 deletions(-)
>
> diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
> index 496d11c92c97..033f6efd92d3 100644
> --- a/scripts/Kconfig.include
> +++ b/scripts/Kconfig.include
> @@ -42,9 +42,6 @@ $(error-if,$(failure,command -v $(LD)),linker '$(LD)' not found)
> # Fail if the linker is gold as it's not capable of linking the kernel proper
> $(error-if,$(success, $(LD) -v | grep -q gold), gold linker '$(LD)' not supported)
>
> -# gcc version including patch level
> -gcc-version := $(shell,$(srctree)/scripts/gcc-version.sh $(CC))
> -
> # machine bit flags
> # $(m32-flag): -m32 if the compiler supports it, or an empty string otherwise.
> # $(m64-flag): -m64 if the compiler supports it, or an empty string otherwise.
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 356601994f3a..9fcbfac15d1d 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -46,7 +46,7 @@ include $(kbuild-file)
> include scripts/Makefile.lib
>
> # Do not include host rules unless needed
> -ifneq ($(hostprogs)$(hostlibs-y)$(hostlibs-m)$(hostcxxlibs-y)$(hostcxxlibs-m),)
> +ifneq ($(hostprogs)$(hostcxxlibs-y)$(hostcxxlibs-m),)
> include scripts/Makefile.host
> endif
>
> diff --git a/scripts/Makefile.clean b/scripts/Makefile.clean
> index 1e4206566a82..075f0cc2d8d7 100644
> --- a/scripts/Makefile.clean
> +++ b/scripts/Makefile.clean
> @@ -30,7 +30,6 @@ subdir-ymn := $(addprefix $(obj)/,$(subdir-ymn))
> __clean-files := $(extra-y) $(extra-m) $(extra-) \
> $(always) $(always-y) $(always-m) $(always-) $(targets) $(clean-files) \
> $(hostprogs) $(hostprogs-y) $(hostprogs-m) $(hostprogs-) \
> - $(hostlibs-y) $(hostlibs-m) $(hostlibs-) \
> $(hostcxxlibs-y) $(hostcxxlibs-m)
>
> __clean-files := $(filter-out $(no-clean-files), $(__clean-files))
> diff --git a/scripts/Makefile.host b/scripts/Makefile.host
> index 3b7121d43324..2045855d0b75 100644
> --- a/scripts/Makefile.host
> +++ b/scripts/Makefile.host
> @@ -39,7 +39,6 @@ $(obj)/%.tab.c $(obj)/%.tab.h: $(src)/%.y FORCE
> # They are linked as C++ code to the executable qconf
>
> __hostprogs := $(sort $(hostprogs))
> -host-cshlib := $(sort $(hostlibs-y) $(hostlibs-m))
> host-cxxshlib := $(sort $(hostcxxlibs-y) $(hostcxxlibs-m))
>
> # C code
> @@ -63,7 +62,6 @@ host-cxxmulti := $(foreach m,$(__hostprogs),$(if $($(m)-cxxobjs),$(m)))
> host-cxxobjs := $(sort $(foreach m,$(host-cxxmulti),$($(m)-cxxobjs)))
>
> # Object (.o) files used by the shared libaries
> -host-cshobjs := $(sort $(foreach m,$(host-cshlib),$($(m:.so=-objs))))
> host-cxxshobjs := $(sort $(foreach m,$(host-cxxshlib),$($(m:.so=-objs))))
>
> host-csingle := $(addprefix $(obj)/,$(host-csingle))
> @@ -71,9 +69,7 @@ host-cmulti := $(addprefix $(obj)/,$(host-cmulti))
> host-cobjs := $(addprefix $(obj)/,$(host-cobjs))
> host-cxxmulti := $(addprefix $(obj)/,$(host-cxxmulti))
> host-cxxobjs := $(addprefix $(obj)/,$(host-cxxobjs))
> -host-cshlib := $(addprefix $(obj)/,$(host-cshlib))
> host-cxxshlib := $(addprefix $(obj)/,$(host-cxxshlib))
> -host-cshobjs := $(addprefix $(obj)/,$(host-cshobjs))
> host-cxxshobjs := $(addprefix $(obj)/,$(host-cxxshobjs))
>
> #####
> @@ -140,13 +136,6 @@ quiet_cmd_host-cxxobjs = HOSTCXX $@
> $(host-cxxobjs): $(obj)/%.o: $(src)/%.cc FORCE
> $(call if_changed_dep,host-cxxobjs)
>
> -# Compile .c file, create position independent .o file
> -# host-cshobjs -> .o
> -quiet_cmd_host-cshobjs = HOSTCC -fPIC $@
> - cmd_host-cshobjs = $(HOSTCC) $(hostc_flags) -fPIC -c -o $@ $<
> -$(host-cshobjs): $(obj)/%.o: $(src)/%.c FORCE
> - $(call if_changed_dep,host-cshobjs)
> -
> # Compile .c file, create position independent .o file
> # Note that plugin capable gcc versions can be either C or C++ based
> # therefore plugin source files have to be compilable in both C and C++ mode.
> @@ -157,16 +146,6 @@ quiet_cmd_host-cxxshobjs = HOSTCXX -fPIC $@
> $(host-cxxshobjs): $(obj)/%.o: $(src)/%.c FORCE
> $(call if_changed_dep,host-cxxshobjs)
>
> -# Link a shared library, based on position independent .o files
> -# *.o -> .so shared library (host-cshlib)
> -quiet_cmd_host-cshlib = HOSTLLD -shared $@
> - cmd_host-cshlib = $(HOSTCC) $(KBUILD_HOSTLDFLAGS) -shared -o $@ \
> - $(addprefix $(obj)/, $($(target-stem)-objs)) \
> - $(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(target-stem).so)
> -$(host-cshlib): FORCE
> - $(call if_changed,host-cshlib)
> -$(call multi_depend, $(host-cshlib), .so, -objs)
> -
> # Link a shared library, based on position independent .o files
> # *.o -> .so shared library (host-cxxshlib)
> quiet_cmd_host-cxxshlib = HOSTLLD -shared $@
> @@ -178,4 +157,4 @@ $(host-cxxshlib): FORCE
> $(call multi_depend, $(host-cxxshlib), .so, -objs)
>
> targets += $(host-csingle) $(host-cmulti) $(host-cobjs)\
> - $(host-cxxmulti) $(host-cxxobjs) $(host-cshlib) $(host-cshobjs) $(host-cxxshlib) $(host-cxxshobjs)
> + $(host-cxxmulti) $(host-cxxobjs) $(host-cxxshlib) $(host-cxxshobjs)
> diff --git a/scripts/gcc-plugin.sh b/scripts/gcc-plugin.sh
> index d3caefe53eab..b79fd0bea838 100755
> --- a/scripts/gcc-plugin.sh
> +++ b/scripts/gcc-plugin.sh
> @@ -1,49 +1,14 @@
> #!/bin/sh
> # SPDX-License-Identifier: GPL-2.0
> -srctree=$(dirname "$0")
> -
> -SHOW_ERROR=
> -if [ "$1" = "--show-error" ] ; then
> - SHOW_ERROR=1
> - shift || true
> -fi
> -
> -gccplugins_dir=$($3 -print-file-name=plugin)
> -plugincc=$($1 -E -x c++ - -o /dev/null -I"${srctree}"/gcc-plugins -I"${gccplugins_dir}"/include 2>&1 <<EOF
> -#include "gcc-common.h"
> -#if BUILDING_GCC_VERSION >= 4008 || defined(ENABLE_BUILD_WITH_CXX)
> -#warning $2 CXX
> -#else
> -#warning $1 CC
> -#endif
> -EOF
> -)
>
> -if [ $? -ne 0 ]
> -then
> - if [ -n "$SHOW_ERROR" ] ; then
> - echo "${plugincc}" >&2
> - fi
> - exit 1
> -fi
> +set -e
>
> -case "$plugincc" in
> - *"$1 CC"*)
> - echo "$1"
> - exit 0
> - ;;
> -
> - *"$2 CXX"*)
> - # the c++ compiler needs another test, see below
> - ;;
> +srctree=$(dirname "$0")
>
> - *)
> - exit 1
> - ;;
> -esac
> +gccplugins_dir=$($* -print-file-name=plugin)
>
> # we need a c++ compiler that supports the designated initializer GNU extension
> -plugincc=$($2 -c -x c++ -std=gnu++98 - -fsyntax-only -I"${srctree}"/gcc-plugins -I"${gccplugins_dir}"/include 2>&1 <<EOF
> +$HOSTCC -c -x c++ -std=gnu++98 - -fsyntax-only -I $srctree/gcc-plugins -I $gccplugins_dir/include 2>/dev/null <<EOF
> #include "gcc-common.h"
> class test {
> public:
> @@ -52,15 +17,3 @@ public:
> .test = 1
> };
> EOF
> -)
> -
> -if [ $? -eq 0 ]
> -then
> - echo "$2"
> - exit 0
> -fi
> -
> -if [ -n "$SHOW_ERROR" ] ; then
> - echo "${plugincc}" >&2
> -fi
> -exit 1
> diff --git a/scripts/gcc-plugins/Kconfig b/scripts/gcc-plugins/Kconfig
> index 7b63c819610c..a857d69322b4 100644
> --- a/scripts/gcc-plugins/Kconfig
> +++ b/scripts/gcc-plugins/Kconfig
> @@ -1,13 +1,4 @@
> # SPDX-License-Identifier: GPL-2.0-only
> -preferred-plugin-hostcc := $(if-success,[ $(gcc-version) -ge 40800 ],$(HOSTCXX),$(HOSTCC))
> -
> -config PLUGIN_HOSTCC
> - string
> - default "$(shell,$(srctree)/scripts/gcc-plugin.sh "$(preferred-plugin-hostcc)" "$(HOSTCXX)" "$(CC)")" if CC_IS_GCC
> - help
> - Host compiler used to build GCC plugins. This can be $(HOSTCXX),
> - $(HOSTCC), or a null string if GCC plugin is unsupported.
> -
> config HAVE_GCC_PLUGINS
> bool
> help
> @@ -17,7 +8,8 @@ config HAVE_GCC_PLUGINS
> menuconfig GCC_PLUGINS
> bool "GCC plugins"
> depends on HAVE_GCC_PLUGINS
> - depends on PLUGIN_HOSTCC != ""
> + depends on CC_IS_GCC && GCC_VERSION >= 40800
> + depends on $(success,$(srctree)/scripts/gcc-plugin.sh $(CC))
> default y
> help
> GCC plugins are loadable modules that provide extra features to the
> diff --git a/scripts/gcc-plugins/Makefile b/scripts/gcc-plugins/Makefile
> index efff00959a9c..f22858b2c3d6 100644
> --- a/scripts/gcc-plugins/Makefile
> +++ b/scripts/gcc-plugins/Makefile
> @@ -1,18 +1,9 @@
> # SPDX-License-Identifier: GPL-2.0
> -PLUGINCC := $(CONFIG_PLUGIN_HOSTCC:"%"=%)
> GCC_PLUGINS_DIR := $(shell $(CC) -print-file-name=plugin)
>
> -ifeq ($(PLUGINCC),$(HOSTCC))
> - HOSTLIBS := hostlibs
> - HOST_EXTRACFLAGS += -I$(GCC_PLUGINS_DIR)/include -I$(src) -std=gnu99 -ggdb
> - export HOST_EXTRACFLAGS
> -else
> - HOSTLIBS := hostcxxlibs
> - HOST_EXTRACXXFLAGS += -I$(GCC_PLUGINS_DIR)/include -I$(src) -std=gnu++98 -fno-rtti
> - HOST_EXTRACXXFLAGS += -fno-exceptions -fasynchronous-unwind-tables -ggdb
> - HOST_EXTRACXXFLAGS += -Wno-narrowing -Wno-unused-variable -Wno-c++11-compat
> - export HOST_EXTRACXXFLAGS
> -endif
> +HOST_EXTRACXXFLAGS += -I$(GCC_PLUGINS_DIR)/include -I$(src) -std=gnu++98 -fno-rtti
> +HOST_EXTRACXXFLAGS += -fno-exceptions -fasynchronous-unwind-tables -ggdb
> +HOST_EXTRACXXFLAGS += -Wno-narrowing -Wno-unused-variable -Wno-c++11-compat
>
> $(obj)/randomize_layout_plugin.o: $(objtree)/$(obj)/randomize_layout_seed.h
> quiet_cmd_create_randomize_layout_seed = GENSEED $@
> @@ -22,9 +13,9 @@ $(objtree)/$(obj)/randomize_layout_seed.h: FORCE
> $(call if_changed,create_randomize_layout_seed)
> targets = randomize_layout_seed.h randomize_layout_hash.h
>
> -$(HOSTLIBS)-y := $(foreach p,$(GCC_PLUGIN),$(if $(findstring /,$(p)),,$(p)))
> -always-y := $($(HOSTLIBS)-y)
> +hostcxxlibs-y := $(foreach p,$(GCC_PLUGIN),$(if $(findstring /,$(p)),,$(p)))
> +always-y := $(hostcxxlibs-y)
>
> -$(foreach p,$($(HOSTLIBS)-y:%.so=%),$(eval $(p)-objs := $(p).o))
> +$(foreach p,$(hostcxxlibs-y:%.so=%),$(eval $(p)-objs := $(p).o))
>
> clean-files += *.so
> --
> 2.17.1
>
--
Kees Cook
next prev parent reply other threads:[~2020-03-30 5:22 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-29 11:08 [PATCH] gcc-plugins: drop support for GCC <= 4.7 Masahiro Yamada
2020-03-30 4:27 ` Kees Cook [this message]
2020-03-30 5:12 ` Masahiro Yamada
-- strict thread matches above, loose matches on Subject: below --
2020-03-30 5:42 Alexey Dobriyan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=202003292126.5105600A@keescook \
--to=keescook@chromium.org \
--cc=kernel-hardening@lists.openwall.com \
--cc=linux-kbuild@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=masahiroy@kernel.org \
--cc=michal.lkml@markovi.net \
--cc=re.emese@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.