[PATCH v4 29/31] gcc-plugins: test plugin support in Kconfig and clean up Makefile

Masahiro Yamada
2018-05-17T06:19:16Z

Run scripts/gcc-plugin.sh from Kconfig so that users can enable
GCC_PLUGINS only when the compiler supports building plugins.

Kconfig defines a new symbol, PLUGIN_HOSTCC. This will contain
the compiler (g++ or gcc) used for building plugins, or empty
if the plugin can not be supported at all.

This allows us to remove all ugly testing in Makefile.gcc-plugins.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

Changes in v4:
- Use if-success macro for clean-up

Changes in v3:
- Respin to keep scripts/gcc-plugin.sh as-is.

Changes in v2: None

arch/Kconfig | 10 ++++++
scripts/Kconfig.include | 3 ++
scripts/Makefile.gcc-plugins | 79 ++++++++++++--------------------------------
scripts/gcc-plugins/Makefile | 1 +
4 files changed, 36 insertions(+), 57 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index ca32950..70f585f 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -401,6 +401,15 @@ config SECCOMP_FILTER

See Documentation/prctl/seccomp_filter.txt for details.

+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))"
+ 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
@@ -410,6 +419,7 @@ config HAVE_GCC_PLUGINS
menuconfig GCC_PLUGINS
bool "GCC plugins"
depends on HAVE_GCC_PLUGINS
+ depends on PLUGIN_HOSTCC != ""
depends on !COMPILE_TEST
help
GCC plugins are loadable modules that provide extra features to the
diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
index b1502f4..bfecf61 100644
--- a/scripts/Kconfig.include
+++ b/scripts/Kconfig.include
@@ -22,3 +22,6 @@ cc-option = $(success, $(CC) -Werror $(1) -E -x c /dev/null -o /dev/null)
# $(ld-option,<flag>)
# y if the linker supports <flag>, n otherwise
ld-option = $(success, $(LD) -v $(1))
+
+# gcc version including patch level
+gcc-version := $(shell, $(srctree)/scripts/gcc-version.sh -p $(CC) | sed 's/^0*//')
diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins
index 1e92353..da5d38d 100644
--- a/scripts/Makefile.gcc-plugins
+++ b/scripts/Makefile.gcc-plugins
@@ -1,72 +1,37 @@
# SPDX-License-Identifier: GPL-2.0
-ifdef CONFIG_GCC_PLUGINS
- __PLUGINCC := $(call cc-ifversion, -ge, 0408, $(HOSTCXX), $(HOSTCC))
- PLUGINCC := $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-plugin.sh "$(__PLUGINCC)" "$(HOSTCXX)" "$(CC)")
-
- SANCOV_PLUGIN := -fplugin=$(objtree)/scripts/gcc-plugins/sancov_plugin.so
-
- gcc-plugin-$(CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) += cyc_complexity_plugin.so
+gcc-plugin-$(CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) += cyc_complexity_plugin.so

- gcc-plugin-$(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) += latent_entropy_plugin.so
- gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) += -DLATENT_ENTROPY_PLUGIN
- ifdef CONFIG_GCC_PLUGIN_LATENT_ENTROPY
+gcc-plugin-$(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) += latent_entropy_plugin.so
+gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) += -DLATENT_ENTROPY_PLUGIN
+ifdef CONFIG_GCC_PLUGIN_LATENT_ENTROPY
DISABLE_LATENT_ENTROPY_PLUGIN += -fplugin-arg-latent_entropy_plugin-disable
- endif
-
- ifdef CONFIG_GCC_PLUGIN_SANCOV
- # It is needed because of the gcc-plugin.sh and gcc version checks.
- gcc-plugin-$(CONFIG_GCC_PLUGIN_SANCOV) += sancov_plugin.so
-
- ifeq ($(PLUGINCC),)
- $(warning warning: cannot use CONFIG_KCOV: -fsanitize-coverage=trace-pc is not supported by compiler)
- endif
- endif
-
- gcc-plugin-$(CONFIG_GCC_PLUGIN_STRUCTLEAK) += structleak_plugin.so
- gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STRUCTLEAK_VERBOSE) += -fplugin-arg-structleak_plugin-verbose
- gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL) += -fplugin-arg-structleak_plugin-byref-all
- gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STRUCTLEAK) += -DSTRUCTLEAK_PLUGIN
+endif

- gcc-plugin-$(CONFIG_GCC_PLUGIN_RANDSTRUCT) += randomize_layout_plugin.so
- gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_RANDSTRUCT) += -DRANDSTRUCT_PLUGIN
- gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_RANDSTRUCT_PERFORMANCE) += -fplugin-arg-randomize_layout_plugin-performance-mode
+gcc-plugin-$(CONFIG_GCC_PLUGIN_SANCOV) += sancov_plugin.so
+gcc-plugin-$(CONFIG_GCC_PLUGIN_STRUCTLEAK) += structleak_plugin.so
+gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STRUCTLEAK_VERBOSE) += -fplugin-arg-structleak_plugin-verbose
+gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL) += -fplugin-arg-structleak_plugin-byref-all
+gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STRUCTLEAK) += -DSTRUCTLEAK_PLUGIN

- GCC_PLUGINS_CFLAGS := $(strip $(addprefix -fplugin=$(objtree)/scripts/gcc-plugins/, $(gcc-plugin-y)) $(gcc-plugin-cflags-y))
+gcc-plugin-$(CONFIG_GCC_PLUGIN_RANDSTRUCT) += randomize_layout_plugin.so
+gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_RANDSTRUCT) += -DRANDSTRUCT_PLUGIN
+gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_RANDSTRUCT_PERFORMANCE) += -fplugin-arg-randomize_layout_plugin-performance-mode

- export PLUGINCC GCC_PLUGINS_CFLAGS GCC_PLUGIN GCC_PLUGIN_SUBDIR
- export SANCOV_PLUGIN DISABLE_LATENT_ENTROPY_PLUGIN
+GCC_PLUGINS_CFLAGS := $(strip $(addprefix -fplugin=$(objtree)/scripts/gcc-plugins/, $(gcc-plugin-y)) $(gcc-plugin-cflags-y))

- ifneq ($(PLUGINCC),)
- # SANCOV_PLUGIN can be only in CFLAGS_KCOV because avoid duplication.
- GCC_PLUGINS_CFLAGS := $(filter-out $(SANCOV_PLUGIN), $(GCC_PLUGINS_CFLAGS))
- endif
+export GCC_PLUGINS_CFLAGS GCC_PLUGIN GCC_PLUGIN_SUBDIR
+export DISABLE_LATENT_ENTROPY_PLUGIN

- KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
- GCC_PLUGIN := $(gcc-plugin-y)
- GCC_PLUGIN_SUBDIR := $(gcc-plugin-subdir-y)
-endif
+# SANCOV_PLUGIN can be only in CFLAGS_KCOV because avoid duplication.
+GCC_PLUGINS_CFLAGS := $(filter-out %/sancov_plugin.so, $(GCC_PLUGINS_CFLAGS))

-# If plugins aren't supported, abort the build before hard-to-read compiler
-# errors start getting spewed by the main build.
-PHONY += gcc-plugins-check
-gcc-plugins-check: FORCE
-ifdef CONFIG_GCC_PLUGINS
- ifeq ($(PLUGINCC),)
- ifneq ($(GCC_PLUGINS_CFLAGS),)
- ifeq ($(call cc-ifversion, -ge, 0405, y), y)
- $(Q)$(srctree)/scripts/gcc-plugin.sh --show-error "$(__PLUGINCC)" "$(HOSTCXX)" "$(CC)" || true
- @echo "Cannot use CONFIG_GCC_PLUGINS: your gcc installation does not support plugins, perhaps the necessary headers are missing?" >&2 && exit 1
- else
- @echo "Cannot use CONFIG_GCC_PLUGINS: your gcc version does not support plugins, you should upgrade it to at least gcc 4.5" >&2 && exit 1
- endif
- endif
- endif
-endif
- @:
+KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
+GCC_PLUGIN := $(gcc-plugin-y)
+GCC_PLUGIN_SUBDIR := $(gcc-plugin-subdir-y)

# Actually do the build, if requested.
PHONY += gcc-plugins
-gcc-plugins: scripts_basic gcc-plugins-check
+gcc-plugins: scripts_basic
ifdef CONFIG_GCC_PLUGINS
$(Q)$(MAKE) $(build)=scripts/gcc-plugins
endif
diff --git a/scripts/gcc-plugins/Makefile b/scripts/gcc-plugins/Makefile
index e2ff425..c47198c 100644
--- a/scripts/gcc-plugins/Makefile
+++ b/scripts/gcc-plugins/Makefile
@@ -1,4 +1,5 @@
# SPDX-License-Identifier: GPL-2.0
+PLUGINCC := $(CONFIG_PLUGIN_HOSTCC:"%"=%)
GCC_PLUGINS_DIR := $(shell $(CC) -print-file-name=plugin)

ifeq ($(PLUGINCC),$(HOSTCC))
--
2.7.4