GCC plugin infrastructure

This patch allows to build the whole kernel with GCC plugins. It was ported from
grsecurity/PaX. The infrastructure supports building out-of-tree modules and
building in a separate directory. Cross-compilation is supported too.
Currently the x86, arm, arm64 and uml architectures enable plugins.

The directory of the gcc plugins is scripts/gcc-plugins. You can use a file or a directory
there. The plugins compile with these options:
 * -fno-rtti: gcc is compiled with this option so the plugins must use it too
 * -fno-exceptions: this is inherited from gcc too
 * -fasynchronous-unwind-tables: this is inherited from gcc too
 * -ggdb: it is useful for debugging a plugin (better backtrace on internal
    errors)
 * -Wno-narrowing: to suppress warnings from gcc headers (ipa-utils.h)
 * -Wno-unused-variable: to suppress warnings from gcc headers (gcc_version
    variable, plugin-version.h)

The infrastructure introduces a new Makefile target called gcc-plugins. It
supports all gcc versions from 4.5 to 6.0. The scripts/gcc-plugin.sh script
chooses the proper host compiler (gcc-4.7 can be built by either gcc or g++).
This script also checks the availability of the included headers in
scripts/gcc-plugins/gcc-common.h.

The gcc-common.h header contains frequently included headers for GCC plugins
and it has a compatibility layer for the supported gcc versions.

The gcc-generate-*-pass.h headers automatically generate the registration
structures for GIMPLE, SIMPLE_IPA, IPA and RTL passes.

Note that 'make clean' keeps the *.so files (only the distclean or mrproper
targets clean all) because they are needed for out-of-tree modules.

Based on work created by the PaX Team.

Signed-off-by: Emese Revfy <re.emese@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Michal Marek <mmarek@suse.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/scripts/gcc-plugins/Makefile b/scripts/gcc-plugins/Makefile
new file mode 100644
index 000000000000..a4c93419d5d1
--- /dev/null
+++ b/scripts/gcc-plugins/Makefile
@@ -0,0 +1,20 @@
+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$(src) -std=gnu++98 -fno-rtti
+  HOST_EXTRACXXFLAGS += -fno-exceptions -fasynchronous-unwind-tables -ggdb
+  HOST_EXTRACXXFLAGS += -Wno-narrowing -Wno-unused-variable
+  export HOST_EXTRACXXFLAGS
+endif
+
+export GCCPLUGINS_DIR HOSTLIBS
+
+$(HOSTLIBS)-y := $(GCC_PLUGIN)
+always := $($(HOSTLIBS)-y)
+
+clean-files += *.so